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Review of Particle Properties
Abstract
DOI:https://doi.org/10.1103/PhysRevD.45.S1
... They are relatively large because in general few events were observed. For very few events (<7) only an upper bound for the actual rate could be estimated (the value between brackets for the rescue rates in the cyclin treated extracts) (Particle Data Group, 1990). To estimate the average values for vg and v~ we measured systematically length changes over fixed time intervals. ...
... The given standard errors are relatively large because in general few events were observed. For very few events (less than seven) only an upper bound for the actual rate could be estimated (the value between brackets for the rescue rates in the cyclin treated extracts) (Particle Data Group, 1990). The values of J and <L> were calculated from the dynamical parameters with equations 5 and 8. Standard error propagation (Particle Data Group, 1990) provides the error in <L>. ...
... For very few events (less than seven) only an upper bound for the actual rate could be estimated (the value between brackets for the rescue rates in the cyclin treated extracts) (Particle Data Group, 1990). The values of J and <L> were calculated from the dynamical parameters with equations 5 and 8. Standard error propagation (Particle Data Group, 1990) provides the error in <L>. Note that, because of the non-linear dependence on the transition rates (f~, f,~0 and the large uncertainities for these rates, this error turns out to be especially large for large values of <L>. ...
In eukaryotic cells, the onset of mitosis involves cyclin molecules which interact with proteins of the cdc2 family to produce active kinases. In vertebrate cells, cyclin A dependent kinases become active in S- and pro-phases, whereas a cyclin B-dependent kinase is mostly active in metaphase. It has recently been shown that, when added to Xenopus egg extracts, bacterially produced A- and B-type cyclins associate predominantly with the same kinase catalytic subunit, namely p34cdc2, and induce its histone H1 kinase activity with different kinetics. Here, we show that in the same cell free system, both the addition of cyclin A and cyclin B changes microtubule behavior. However, the cyclin A-dependent kinase does not induce a dramatic shortening of centrosome-nucleated microtubules whereas the cyclin B-dependent kinase does, as previously reported. Analysis of the parameters of microtubule dynamics by fluorescence video microscopy shows that the dramatic shortening induced by the cyclin B-dependent kinase is correlated with a several fold increase in catastrophe frequency, an effect not observed with the cyclin A-dependent kinase. Using a simple mathematical model, we show how the length distributions of centrosome-nucleated microtubules relate to the four parameters that describe microtubule dynamics. These four parameters define a threshold between unlimited microtubule growth and the establishment of steady-state dynamics, which implies that well defined steady-state length distributions can be produced by regulating precisely the respective values of the dynamical parameters. Moreover, the dynamical model predicts that increasing catastrophe frequency is more efficient than decreasing the rescue frequency to reduce the average steady state length of microtubules. These theoretical results are quantitatively confirmed by the experimental data.
... Similarly, a vertex fit of the D + decay products is made, where the D + candidate is constrained to originate from the corresponding PV. In D + → K 0 π + decays, the neutral kaon is reconstructed via decays into two charged pions, which are dominated by decays of the short-lived neutral kaon, K 0 S. The mass of the K 0 meson is constrained to the nominal mass of the K 0 S state [25]. Decays of K 0 S → π + π − are reconstructed using only K 0 S mesons that decay early enough for the secondary pions to be reconstructed in the vertex detector. ...
... where the threshold δm 0 is fixed to the known π + mass [25]. The parameters A and B describe the shape and are common to D 0 and D 0 decays. ...
A measurement of the time-integrated CP asymmetry in the Cabibbo-suppressed decay $D^0 → K^- K^+$ is performed using ppcollision data, corresponding to an integrated luminosity of 3 $fb^{−1}$, collected with the LHCb detector at centre-of-mass energies of 7 and 8TeV. The flavour of the charm meson at production is determined from the charge of the pion in $D^{∗+} → D^0\pi^+ and D^{∗−} → \overline{D}^0\pi^-$ decays. The time-integrated CP asymmetry $A_{CP}(K^- K^+)$ is obtained assuming negligible CP violation in charm mixing and in Cabibbo-favoured $D^0 → K^−\pi^+, D^+ → K^-\pi^+\pi^+$ and $D^+ → \overline{K}^0\pi^+$ decays used as calibration channels. It is found to be $A_{CP}(K^- K^+)$ = (0.14 ± 0.15 (stat) ± 0.10 (syst))%. A combination of this result with previous LHCb measurements yields $A_{CP}(K^- K^+)$ = (0.04 ± 0.12 (stat) ± 0.10 (syst))%, $A_{CP}(\pi^-\pi^+)$ = (0.07 ± 0.14 (stat) ± 0.11 (syst))%. These are the most precise measurements from a single experiment. The result for $A_{CP}(K^- K^+)$ is the most precise determination of a time-integrated CP asymmetry in the charm sector to date, and neither measurement shows evidence of CP asymmetry.
... Charged mesons produced from a quark and antiquark can decay to a charged lepton pair when these objects annihilate via a virtual W AE boson, as shown in Fig. 3. Though the leptonic decays of open flavor mesons belong to rare decay [62,63], they have clear experimental signatures due to the presence of a highly energetic lepton in the final state, and such decays are very clean due to the absence of hadrons in the final state [64]. The leptonic width of the B meson is computed using the relation [1] ...
... From Eqs. (62) and (63) one can get the differences in the mass and width, which are given as ...
In the framework of the relativistic independent quark model, the mass spectra and decay properties of B and Bs mesons are obtained using a Martin-like potential for the quark confinement. The predicted excited states are in good agreement with the experimental results as well as with the lattice QCD and other theoretical predictions. For instance, the B2(5747) as 1P32, B1(5721) as 1P31, and B0(5732) as 1P30 are identified. The spectroscopic parameters are used to calculate the electromagnetic transitions, pseudoscalar decay constants, hadronic decay widths, and leptonic decay widths. The present result for the decay constant, fB(1S)=188.56 MeV, is in good agreement with recent lattice results (UKQCD Collaboration, Fermilab) and comparable with the experimental value of (206.7±8.9). The pseudoscalar decay constant for the Bs meson obtained here, fBs(1S)=240.21 MeV, is in very good agreement with recent lattice QCD and QCD sum rule predictions. The predicted branching ratio for B+→τ+ντ (1.354×10−4) is in accordance with the value, (1.65±0.34)×10−4 reported by the Particle Data Group (PDG). The branching ratios of the rare decays Bs0→μ+μ− ((3.1±0.7)×10−9) and B0→μ+μ− (<6.3×10−10) as observed by the CMS and LHCb Collaborations very recently are in accordance with our predictions of 3.602×10−9 and 1.018×10−10, respectively. The Cabibbo-favored hadronic branching ratios of B0→D−π+ (3.724×10−3), B0→D*−π+ (3.475×10−3), and Bs→Ds−ρ+ (3.800×10−3) are in good agreement with the respective PDG values. The mixing parameters xq, χq for B0−B¯0 (xd=0.769, χd=0.1859) and Bs−B¯s (xs=26.41, χs=0.49929) are also found to be in excellent agreement with the PDG values of (0.770±0.008, 0.1862±0.0023) and (26.49±0.29, 0.499292±0.000016), respectively.
... Various experimental searches for ionizing tachyons have been described in a number of papers. A large majority of them is cited in Refs.5678910 . The experiments were of low and high energy type. ...
... A single possibly positive result [11] has also been rejected [5] . This situation has presumably disheartened most experimenters (the last relevant record in the Review of Particle Properties [9] is dated 1982 [8]), though some efforts were still made [10] . According to our hypothesis, however, air shower (and accelerator ) experiments may be successful and they are discussed in Section 5. Though the tachyons considered in this paper are ionizing objects, experiments yielding tachyonic (?) neutrinos are briefly commented in Section 6, where also an unfortunate terminology is criticized. ...
An exact solution of the Einstein-Maxwell equations yields a general relativistic picture of the tachyonic phenomenon, suggesting a hypothesis on the tachyon creation. The hypothesis says that the tachyon is produced when a neutral and very heavy (over 75 GeV/c2) subatomic particle is placed in electric and magnetic fields that are perpendicular, very strong (over 6.9 × 1017 esu/cm2 or oersted), and the squared ratio of their strength lies in the interval (1,5]. Such conditions can occur when nonpositive subatomic particles of high energy strike atomic nuclei other than the proton. The kinematical relations for the produced tachyon are given. Previous searches for tachyons in air showers and some possible causes of their negative results are discussed. Experiments with the use of the strongest colliders and improvements in the air shower experiments are suggested. An unfortunate terminology is also discussed.
... The normalization is obtained from the number of J/ψ K − events and the known rate of B(B − → J/ψ K − , J/ψ → µ + µ − ) = (6.04±0.26)×10 −5 [14,15]. ...
... with G F = 1.166377 × 10 −5 GeV −2 , f B = 0.19 GeV, f π = 0.131 GeV, |V ub | = 0.004, |V ud | = 0.9738, m B = 5.279 GeV, τ B = 1.671 ps, and = 6.582 × 10 −25 GeV s [15]. The total neutrino decay width, Γ N , is a function of m N and proportional to |V µ4 | 2 . ...
A search for heavy Majorana neutrinos produced in the $B^- \to \pi^+\mu^-\mu^-$ decay mode is performed using 3 fb$^{-1}$ of integrated luminosity collected with the LHCb detector in $pp$ collisions at center-of-mass energies of 7 TeV and 8 TeV at the LHC. Neutrinos with masses in the range 250-5000 MeV and lifetimes from zero to 1000 ps are probed. In the absence of a signal, upper limits are set on the branching fraction ${\cal{B}}(B^- \to \pi^+\mu^-\mu^-)$ as functions of neutrino mass and lifetime. These limits are on the order of $10^{-9}$ for short neutrino lifetimes of 1 ps or less. Limits are also set on the coupling between the muon and a possible fourth-generation neutrino.
... (4), Ft. is assumed to be 9F (Q). It is easy to check that for Q2 = m 2 the function ~ reduces to the cross section [6 ] for the production of a real t7 pair, i.e. limQ2__,m2 ~ (s; Q2, m 2) = a(e+e -~ tt). ...
The quasi amplitude of probability, a concept associated with the Wigner function, is used to introduce the notion of symplectic density matrix, \(\rho\). The Liouville-Von Neumann equation is derived in phase space by using symmetry. The physical content of \(\rho\) is analyzed in detail, in particular with the study of the classical limit. The first application addresses the problem of quark-antiquark interaction, described by the so-called Cornell potential. The matrix \(\rho\) is calculated, providing a phase space description of the quark-antiquark state. For the model considered here, the quark confinement is derived, such that the distance of confinement is about 4 GeV\(^{-1}\). This result improves theoretical calculations in the literature, approaching to the order of experimental results. Another application is the calculation of \(\rho\) considering mixed state systems. Since \(\rho\) is a density of probability, the entropy is defined without ambiguity, and as such the Gibbs ensemble is introduced for a quantum system in the phase space representation. Then a harmonic oscillator system at finite temperature is studied. The second mixed state system is a maximally entangled bipartite state. In these applications, when it is possible, the nature of \(\rho\) is compared with the Wigner function.
A plan to upgrade the ALICE Inner Tracking System has been proposed, and the Monolithic Active Pixel Sensor, a novel silicon sensor technology, will be employed. The silicon sensor is planned to be investigated with a rotating telescope at the Synchrotron Light Research Institute Beam Test Facility using a 1.2 GeV electron beam. A part of this work is to investigate the pixel sensor telescope when the angle of the Device Under Test (DUT) plane changes. Simulation has been performed with the G4beamline software. Once a G4beamline simulation is completed, a ROOT file is produced. Beam profiles and correlation plots are then analyzed. This data was used to calculate the scattering angle, which was found to be between 0.171 and 0.178 mrad when the DUT plane is perpendicular to the test beam. Furthermore, the simulation result has been compared and agrees with the theoretical calculation within 4.8% error.
A bstract
Estimating the contribution from axial-vector intermediate states to hadronic light-by-light scattering requires input on their transition form factors (TFFs). Due to the L andau –Y ang theorem, any experiment sensitive to these TFFs needs to involve at least one virtual photon, which complicates their measurement. Phenomenologically, the situation is best for the f 1 (1285) resonance, for which information is available from e ⁺ e − → e ⁺ e − f 1 , f 1 → 4 π , f 1 → ργ , f 1 → ϕγ , and f 1 → e ⁺ e − . We provide a comprehensive analysis of the f 1 TFFs in the framework of vector meson dominance, including short-distance constraints, to determine to which extent the three independent TFFs can be constrained from the available experimental input — a prerequisite for improved calculations of the axial-vector contribution to hadronic light-by-light scattering. In particular, we focus on the process f 1 → e ⁺ e − , evidence for which has been reported recently by SND for the first time, and discuss the impact that future improved measurements will have on the determination of the f 1 TFFs.
The three-loop QED mass-dependent contributions to the g−2 of each of the charged leptons with two internal closed fermion loops, sometimes called A3(6)(m1m2,m1m3) in the g−2 literature, is revisited using the Mellin-Barnes (MB) representation technique. Results for the muon and τ lepton anomalous magnetic moments A3,μ(6) and A3,τ(6), which were known as series expansions in the lepton mass ratios up to the first few terms only, are extended to their exact expressions. The contribution to the anomalous magnetic moment of the electron A3,e(6) is also explicitly given in closed form. In addition to this, we show that the different series representations derived from the MB representation collectively converge for all possible values of the masses. Such unexpected behavior is related to the fact that these series bring into play double hypergeometric series that belong to a class of Kampé de Fériet series which we prove to have the same simple convergence and analytic continuation properties as the Appell F1 double hypergeometric series.
We critically review the present status of glueballs, including theoretical and experimental aspects.
We present a set of favored processes where it may be possible to search for these objects. We stress some of the existent problems related to the unambiguous prediction of their properties.
We propose a model which is able to explain the experimental data for the reaction $\pi^- p \rightarrow \phi\phi n$, allowing us to estimate the coupling constants $g_{G\phi\phi}$ e $g_{G\pi\pi}$ of a $2^{++}$ glueball state to $\phi\phi$ e $\pi\pi$, respectively.
There are many theories that have resided these last fifty years within the hazy mist we have been calling the Standard Model (SM) of elementary particles. An attempt is made here to construct a coherent description of the SM today, because only precisely articulated theories can be targeted for annihilation, corroboration, and alteration. To this end it is useful to categorize the facts, mysteries and myths that together build a single conception of the SM. For example, it is argued that constructing a myth for how neutrinos obtain mass is useful for progress. We also advocate for interpreting the cosmological constant, dark matter, baryogenesis, and inflation as four “mysteries of the cosmos” that are indeterminate regarding new particles or interactions, despite a multitude of available particle explanations. Some history of the ever-changing SM is also presented to remind us that today’s SM is not our parents’ SM, nor will it likely be our children’s SM.
At high energy, exclusive meson photo- and electro-production give access to the structure of hadronic matter. At low momentum transfers, the exchange of a few Regge trajectories leads to a comprehensive account of the cross-sections. Among these trajectories, which are related to the mass spectrum of families of mesons, the Pomeron plays an interesting role as it is related to glue-ball excitations. At high momentum transfers, the exchange of these collective excitations is expected to reduce to the exchange of their simplest (quark or gluon) components. However, contributions from unitarity rescattering cuts are relevant even at high energies. In the JLab energy range, the asymptotic regime, where the players in the game are current quarks and massless gluons has not been reached yet. One has to rely on more effective degrees of freedom adapted to the scale of the probe. A consistent picture, the “Partonic Non-Perturbative Regime”, is emerging. The properties of its various components (dressed propagators, effective coupling constants, quark wave functions, shape of the Regge trajectories, etc.) provide us with various links to hadron properties. I will review the status of the field, will put in perspective the current achievements at JLab, SLAC and Hermes, and will assess future developments that are made possible by continuous electron beams at higher energies.
We discuss the origin of the antihelium-3 and -4 events possibly detected by AMS-02. Using up-to-date semianalytical tools, we show that spallation from primary hydrogen and helium nuclei onto the ISM predicts a He3¯ flux typically one to two orders of magnitude below the sensitivity of AMS-02 after 5 years, and a He4¯ flux roughly 5 orders of magnitude below the AMS-02 sensitivity. We argue that dark matter annihilations face similar difficulties in explaining this event. We then entertain the possibility that these events originate from antimatter-dominated regions in the form of anticlouds or antistars. In the case of anticlouds, we show how the isotopic ratio of antihelium nuclei might suggest that BBN has happened in an inhomogeneous manner, resulting in antiregions with a antibaryon-to-photon ratio η¯≃10−3η. We discuss properties of these regions, as well as relevant constraints on the presence of anticlouds in our Galaxy. We present constraints from the survival of anticlouds in the Milky-Way and in the early Universe, as well as from CMB, gamma-ray and cosmic-ray observations. In particular, these require the anticlouds to be almost free of normal matter. We also discuss an alternative where antidomains are dominated by surviving antistars. We suggest that part of the unidentified sources in the 3FGL catalog can originate from anticlouds or antistars. AMS-02 and GAPS data could further probe this scenario.
Summary This document is part of Volume 11 ‘Shielding Against High Energy Radiation’ of Landolt-Börnstein - Group I Elementary Particles, Nuclei and Atoms.
Summary This document is part of Volume 11 ‘Shielding Against High Energy Radiation’ of Landolt-Börnstein - Group I Elementary Particles, Nuclei and Atoms.
Summary This document is part of Volume 11 ‘Shielding Against High Energy Radiation’ of Landolt-Börnstein - Group I Elementary Particles, Nuclei and Atoms.
We develop the improved ladder approximation to QCD in order to apply it to the heavy quark mesons. The resulting Bethe-Salpeter equation is expanded in powers of the inverse heavy quark mass 1/M, and is shown to be consistent with the heavy quark spin symmetry. We calculate numerically the universal leading order BS amplitude for heavy pseudoscalar and vector mesons, and use this to evaluate the Isgur-Wise function and the decay constant FB. The resulting Isgur-Wise function predicts a large charge radius, ρ² = 1.8 − 2.0, which when fitted to the ARGUS data corresponds to the value Vcb = .044 − .050 for the Kobayashi-Maskawa matrix element.
The article contains sections titled:
The final version of the multi-resonance, coupled-channel partial wave analysis with the significant improvement of the πN elastic S11 partial wave is presented. The need for the new, only theoretically predicted P11 resonance is pointed out. The value of the ηN S-wave scattering length is finally unambiguously established.
During the first week of this institute many people expressed some wonder that four lectures had been allotted to discuss the spectroscopy of hadrons with heavy flavour. Surely there are simply not enough such hadrons to warrant a full four hours! A glance at figures 1 and 2, however, should reassure any doubters. Figure 1a) shows the measured mass spectrum of all of the known charmed mesons, while part b) shows the same for of all of the known charmed baryons and figure 2 shows the same for all known bottom mesons. The quark content of the various states named in these figures is summarized in Tables 1 and 2. At this time the only established bottom baryon is the Λb, so there is no corresponding figure for the bottom baryons.1 Because most of the known states are charmed hadrons, this review will mostly cover charm spectroscopy, with a few references to bottom spectroscopy. Finally, whenever these lectures discuss a particular state or reaction, the charge conjugate state or reaction is usually implied. The exceptions will occur when discussing charm production from ∑- beams or \(\bar v\) beams.
An introduction is given to the quark mixing matrix and CP violation. The topics discussed include Classification of Symmetries, the Discrete P, C and CP Symmetries, the Electroweak Model, the Lagrangian of the Electroweak Model, the Quark Mass Terms and the Origin of CP Violation, Spontaneous Symmetry Breaking, the Quark Mixing Matrix, the Number of Families, CP Violation with Three Families, the KM Type Parametrizations of the Quark Mixing Matrix, Unitarity Triangles and the CP Violation Area, the Commutator Formalism for CP Violation, Manifestations of CP Violation, and Comments on CP Violation in the Beauty Sector.
This chapter concerns the basic reactions which occur when radiation encounters matter and the effects produced by these processes. For the experimental nuclear or particle physicist, knowledge of these interactions is of paramount importance. Indeed, as will be seen in the following chapters, these processes are the basis of all current particle detection devices and thus determine the sensitivity and efficiency of a detector. At the same time, these same reactions may also interfere with a measurement by disturbing the physical state of the radiation: for example, by causing energy information to be lost, or deflecting the particle from its original path, or absorbing the particle before it can be observed. A knowledge of these reactions and their magnitudes is thus necessary for experimental design and corrections to data. Finally, these are also the processes which occur when living matter is exposed to radiation.
About 70 years ago, only a small number of “elementary particles”, thought to be the basic building blocks of matter, were known: the proton, the electron, and the photon as the quantum of radiation. All these particles are stable (the neutron is stable only in nuclear matter, the free neutron decays by beta decay: \(n \to p + {e^ - } + \overline \upsilon \)). Owing to the availability of large accelerators, this picture of a few elementary particles has profoundly changed: today, the standard reference “Review of Particle Properties”1 lists more than 100 particles. The number is still growing as the energies and luminosities of accelerators are increased.
In this chapter we consider all of the mesons that are mixed states of all three light flavours up, down and strange. We discuss the quark structure of the multiplets of pseudoscalar and vector mesons and trace back the mass difference between them to a spin-spin interaction. Of special interest are neutral quark–antiquark states containing a light quark and a heavier s-, c- or b-quark, like the \(\vert \mbox{ $\mathrm{K}^{\mathrm{0}}$}\rangle\) or the \(\mathrm{\vert B}^{\mathrm{0}}\rangle\) and their antiparticles. These mesons have very peculiar properties: particle and antiparticle can oscillate into each other and their weak decays violate conservation of CP symmetry. We will discuss these exciting aspects in some detail.
Recent years have seen intense activities in the field of heavy quark physics, and remarkable progress has been made.1–11 In the limit of infinite heavy quark mass, the strong interactions of a heavy quark become much simplified. Namely, the effective QCD Lagrangian becomes independent of the flavor and spin of the heavy quark. For N
f
heavy quark flavors, the new spin and flavor symmetries combine to form a SU(2N
f
) symmetry group (heavy quark symmetry) which is not manifest in the original Lagrangian. Heavy quark symmetry allows us to predict many properties of heavy hadrons, which are taken to be particles containing a single heavy quark. Of course, even in this infinite heavy quark mass limit, low energy hadronic physics (confinement, etc.) remains non-perturbative and there is still no solution to it. What heavy quark symmetry can do for us is to provide simplifying relations among the static and transition properties of the heavy hadrons. For instance, the spin-flavor symmetry implies that the excitation spectrum and transition form factors of a heavy hadron do not depend on the spin and flavor of the heavy quark involved. Thus, in the symmetry limit, the heavy quark behaves like a static color source. This is analogous to the well known case of a hydrogen-like atom, whose excitation spectrum and transition form factors are independent of the mass and spin of its heavy nucleus, which acts as a static charge source.
We report on new measurements for the mass, width and branching ratios for the J/
ψ, ψ′, X
c1
and X
c2
.These charmonium states are formed in exclusive proton-antiproton annihilations at the Fermilab Antiproton Accumulator ring, where stochastically cooled antiprotons are brought into collision with the protons of an internal hydrogen gas jet target. The antiproton energy was precisely controlled and measured allowing for an accurate measurement of the resonance parameters.
Extensions of the constituent quark potential model for mesons are formulated and analyzed which include relativistic dynamics and the full Dirac structure of both positive and negative energy states. The meson wave equations are transformed to configuration space where they can easily be solved numerically. Regge-slopes, the pion form factor and radiative, annihilation decay are studied. We find that the projection on the full Dirac structure of the confining potential and of the meson decay vertices gives unexpected large modifications to the nonrelativistic mass spectra and decay vertices. This paper summarizes the main results of [1, 2].
Spinning particles have been studied by different authors and in different occasions (see [1] for some references), and actually the interest on spinning particles models revived specially due to the interest on spinning strings. Notwithstanding, producing a classical spinning particle model that after quantization gives Dirac equation has always been a very appealing idea which has been the subject of several interesting papers containing new physical insights and beautiful mathematics. In this paper we plan to study in details some aspects of spinning particle models, and in particular the one proposed by Barut and Zanghi [2], and some of its possible generalizations.
For the present study, we have used the Martin-like potential for the quark confinement. Our predicted states in the S-wave, \(2\ ^3S_1\) (2605.86 MeV) and \(2\ ^1S_0\) (2521.72 MeV), are in very good agreement with experimental results of \(2608\pm 2.4 \pm 2.5\) MeV and \(2539.4\pm 4.5\pm 6.8\) MeV, respectively, reported by the BABAR Collaboration. The calculated P-wave D meson states, \(1^3P_2\) (2462.50 MeV), \(1^3P_1\) (2407.56 MeV), \(1^3P_0\) (2373.82 MeV) and \(1^1P_1\) (2423.28 MeV), are in close agreement with experimental average (Particle Data Group) values of \(2462.6 \pm 0.7 \) MeV, \(2427 \pm 26 \pm 25\) MeV, \(2318 \pm 29 \) MeV and \(2421.3 \pm 0.6 \) MeV, respectively. The pseudoscalar decay constant (\(f_P\)= 202.57 MeV) of the D meson is in very good agreement with the experiment as well as with the lattice predictions. The Cabibbo favoured nonleptonic decay branching ratios, BR\((D^0\rightarrow K^- \pi ^+)\) of \(4.071\,\%\) and BR \((D^0\rightarrow K^+ \pi ^-)\) of \(1.135 \times 10^{-4} \), are also in very good agreement with the respective experimental values of \( 3.91 \pm 0.08\,\%\) and \((1.48\pm 0.07) \times 10^{-4}\) reported by CLEO Collaboration. The mixing parameters of the \(D^0 \)–\( \bar{D}^0\) oscillation, \(x_q\) (5.14 \(\times 10^{-3}\)), \(y_q\) (6.02 \(\times 10^{-3}\)) and \(R_M\) (3.13 \(\times 10^{-5}\)), are in very good agreement with BaBar and Belle Collaboration results.
Using 1.16 × 106 BB events collected at the γ(4S) resonance by the CLEO Collaboration at the Cornell Electron Storage Ring (CESR), we have searched for decays of B mesons to exclusive two-body hadronic final states including a Ds+ or a Ds*+ meson. We obtain the 90% confidence level upper limit β (B → Ds(*)+π- + Ds*+p- + Ds(*)+π0 + Ds(*)+η + Ds(*)+p0 + Ds(*)+(ω) × β(Ds+ → φπ+) < 1.8 × 10-5. We have also searched for the W-exchange decays, B0 → Ds(*)-K(*)+.
We have searched for the b-flavored baryon decay Λb→JψΛ0 in pp¯ collisions at s=1.8 TeV with the Collider Detector at Fermilab (CDF). In the JψΛ0 invariant-mass distribution we observe a flat distribution and a small number of events, consistent with no signal. Using the b-quark cross section measured by the CDF we put an upper limit on the b→Λb production fraction times the branching ratio F(Λb)B(Λb→JψΛ0) of 0.50×10−3 at 90% confidence level.
The magnetic moments of $J^P=\frac{3}{2}^+$ decuplet baryons have been
calculated in the chiral constituent quark model ($\chi$CQM) with explicit
results for the contribution coming from the valence quark polarizations, sea
quark polarizations, and their orbital angular momentum. Since the
$J^P=\frac{3}{2}^+$ decuplet baryons have short lifetimes, the experimental
information about them is limited. The $\chi$CQM has important implications for
chiral symmetry breaking as well as SU(3) symmetry breaking since it works in
the region between the QCD confinement scale and the chiral symmetry breaking
scale. The predictions in the model not only give a satisfactory fit when
compared with the experimental data but also show improvement over the other
models. The effect of the confinement on quark masses has also been discussed
in detail and the results of $\chi$CQM are found to improve further with the
inclusion of effective quark masses.
We investigate charmonium production in Pb+Pb collisions at LHC beam energy
$E_{\text {lab}}$=2.76 A TeV at fixed-target experiment ($\sqrt
{s_{\text{NN}}}$=72 GeV). In the frame of a transport approach including cold
and hot nuclear matter effects on charmonium evolution, we focus on the
anti-shadowing effect on the nuclear modification factors $R_{AA}$ and $r_{AA}$
for the $J/\psi$ yield and transverse momentum. The yield is more suppressed at
less forward rapidity ($y_\text{lab}\simeq$2) than that at very forward
rapidity ($y_\text{lab}\simeq$4) due to the shadowing and anti-shadowing in
different rapidity bins.
Upper limits at the 90% confidence level are presented for four- and five-prong semimuonic decays of charm mesons. From a study of four-prong vertices we find B(D0 --> K-pi+pi-mu+nu)/B(D0 --> K-mu+nu) < 0.037 and B(D0 --> (K*BAR (892)pi)-mu+nu)/B(D0 --> K-mu+nu) < 0.043. The five-prong vertices yield the result B(D(S)+ --> eta'mu+nu)/B(D(S)+ --> phimu+nu) < 1.6.
We present the results of a partial reconstruction of the decay channel B- --> D(J)(*)0 pi- performed using the ARGUS detector operating at the e+e- storage-ring DORIS II. In the context of this paper, D(J)(*)0 is an L = 1 excited charm meson decaying to D*+ pi-. The measured product of branching ratios is Br(B- --> D1(0)(2414) pi-).Br(D1(0)-->D*+ pi-) = (0.17 +/- 0.05 +/- 0.04)% where the first error is statistical and the second systematic. No evidence for the decay B- --> D2*0(2459) pi-).Br(D2*0 --> D*+ pi-) < 0.07% at the 90% confidence level.
A search for lepton flavor violating decays of the tau into either three charged leptons or one charged lepton and two charged hadrons was performed using 2.05 ${\mathrm{fb}}^{\ensuremath{-}1}$ of data collected by the CLEO-II experiment at the Cornell Electron Storage Ring. The upper limits obtained for 22 decay branching fractions are several times more stringent than those set previously.
The relative branching fraction RK = Γ(D0 → K-μ+v)/Γ(D0 → μ-X) has been measured by Fermilab experiment E653, using D0 mesons produced by 600 GeV π-. The semimuonic decay sample of 232 events was identified by the decay chain D*+ → D0π+, D0 → μ+h-X, where h is a hadron. The Kμv component was extracted from the joint distribution of these events in the D0 decay variables Mmin and pTh. We find RK = 0.472 ± 0.051 (stat) ± 0.040 (sys), and use a world average of the D0 → Klv branching fraction to obtain the D0 inclusive semimuonic branching fraction B(D0 → μ+X) = (7.67 ± 1.13)%.
We have investigated D+ π- and D*+ π- final states and observed the two established L = 1 charmed mesons, the D1 (2420)0 with mass 2421-2-2+1+2 MeV/c2 and width 20-5-3+6+3 MeV/c2 and the D2* (2460)0 with mass 2465 ± 3 ± 3 MeV/c2 and width 28-7-6+8+6 MeV/c2. Properties of these final states, including their decay angular distributions and spin-parity assignments, have been studied. We identify these two mesons as the jlight = 3 2 doublet predicted by HQET. We also obtain constraints on Γs/ (Γs + ΓD) as a function of the cosine of the relative phase of the two amplitudes in the D1 (2420)0 decay.
This Letter reports the observation and mass measurement of fully reconstructed ${\mathit{B}}_{\mathit{s}}^{0}$ mesons through the decay chain ${\mathit{B}}_{\mathit{s}}^{0}$\ensuremath{\rightarrow}J/\ensuremath{\psi} \ensuremath{\psi}, J/\ensuremath{\psi}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$, \ensuremath{\varphi}\ensuremath{\rightarrow}${\mathit{K}}^{+}$${\mathit{K}}^{\mathrm{\ensuremath{-}}}$ using data obtained at the Collider Detector at Fermilab in p\ifmmode\bar\else\textasciimacron\fi{}p collisions at \ensuremath{\surd}s =1.8 TeV. A signal of 14.0\ifmmode\pm\else\textpm\fi{}4.7 events is observed. Comparison of the ${\mathit{B}}_{\mathit{s}}^{0}$ signal with the kinematically similar decays ${\mathit{B}}^{+}$\ensuremath{\rightarrow}J/\ensuremath{\psi} ${\mathit{K}}^{+}$ and ${\mathit{B}}^{0}$\ensuremath{\rightarrow}J/\ensuremath{\psi} ${\mathrm{K}}^{\mathrm{*}}$(892${)}^{0}$ is presented. The mass of the ${\mathit{B}}_{\mathit{s}}^{0}$ meson is determined to be 5383.3\ifmmode\pm\else\textpm\fi{}4.5(stat)\ifmmode\pm\else\textpm\fi{}5.0(syst) MeV/${\mathit{c}}^{2}$.
From a perspective in which the dynamical contribution of hadrons is
manifested, Cabibbo-angle-favored two-body decays of charm mesons into
final states involving η or η' are studied in consistency with
the other charm meson decays.
The branching ratios of D0 → K0K0 and D0 → Ks0Ks0Ks0 relative to D0 → K0π+π- are reported. The data were accumulated in the 1990-1991 fixed target running period of the Fermilab high energy photoproduction experiment E687. Γ (D0 → K0K0)/Γ (D0 → K0π+π- is measured to be 0.039±0.013±0.013 and Γ (D0→Ks0Ks0Ks0)/Γ (D0 → K0π+π-) is measured to be 0.035±0.012±0.006. We also measure Γ (D0 → K0π+π-/Γ (D0 → K-π+) to be 1.61±0.10±0.15.
We have calculated the decay τ→νπ(K)γ. We present the photon energy spectrum, the meson-photon invariant mass spectrum, and the integrated rate as a function of a photon energy cut or an invariant mass cut. Both the internal bremsstrahlung and the structure-dependent radiation have been taken into account. To this aim we have parametrized the form factors FV and FA, which determine the structure-dependent radiation. Observables especially suited for the measurement of the structure-dependent form factors are found and implications on the width of the a1 discussed. We compare our results with previously published ones.
The fragmentation functions for the heavy mesons of $S$ and $P$ waves are calculated in the framework of perturbative QCD and the nonrelativistic quark model. The results are manifestly process independent. As applications, the production ratios for $P$-wave $\overline{b}c$ mesons to the $b\overline{b}$ production at high energy colliders are predicted. The spin dependence of the fragmentation functions for various states is discussed and the predicted results for the $D ({D}^{*})$ mesons are consistent with the recent experimental data.
A recent isobar-model, partial-wave analysis of piN-->pipiN finds strong indications of the F35 pion-nucleon resonance belonging to the (70,L=2+) baryon multiplet. This conclusion is drawn from recent predictions of baryon decays obtained with baryon compositions determined by the Isgur-Karl quark model. The highly inelastic F35 resonance is observed through its dominant p-wave decay to rhoN.
Recent results involving charmed baryons are discussed. In the past few years, many groups have new, higher statistics studies of the and Σc. Accurate mass measurements and more quantitative results on branching ratios have appeared. The new relative branching ratios are compared with theoretical predictions from quasi-two body calculations and statistical models. Absolute branching ratios are discussed, and various methods for setting an absolute scale are compared. New measurements of the Σc mass and production are discussed, and compared with theoretical models. The recent observation of the , , and Ωc allow a discussion of the charmed baryon mass spectrum. These recent measurements are compared with a number of theoretical predictions, both for the absolute masses and for mass splittings among multiplets. Finally, prospects for the future studies of charmed baryons are discussed.
The solar neutrino data from the Kamiokande II detector have been
analyzed for compatibility with the different solutions in the
Mikheyev-Smirnov-Wolfenstein formalism. The measured recoil-electron
energy spectrum alone disfavors the region of the adiabatic solution at
the 90 percent confidence level.
A data sample of 1040 days from the Kamiokande II detector, consisting
of subsamples of 450 days at electron-energy threshold E(e) greater than
or equal to MeV and 590 days at E(e) greater than or equal to 7.5 MeV,
yields a clear directional correlation of the solar-neutrino-induced
electron events with respect to the sun and a measurement of the
differential electron-energy distribution. These provide unequivocal
evidence for the production of B-8 by fusion in the sun. The measured
flux of B-8 solar neutrinos from the two subsamples relative to a
prediction of the standard solar model is 0.46 + or - 0.05 (stat) + or -
0.06 (syst). The total data sample is tested for short term time
variation and, within the statistical error no significant variation is
observed.
The first measurements of spin-rotation in meson-baryon scattering in
the resonance region are presented. These measurements, for the reaction
π-p → K 0Λ, confirm the main
predictions of a previous partial-wave analysis. Comments are made on
resonant couplings in the reaction π-p → K
0Λ.
A neutrino burst was observed in the Kamiokande II detector on 23
February 1987, 7:35:35 UT (±1 min) during a time interval of 13
sec. The signal consisted of eleven electron events of energy 7.5 to 36
MeV, of which the first two point back to the Large Magellanic Cloud
with angles 18°±18° and 15°±27°.
It is shown that the recently introduced radiative corrections Δ
ŕand Δ ŕw automatically incorporate the
leading higher-order contributions arising from resummation of one-loop
femionic contributions. With slight modifications, they can be made to
include all such contributions (not just the leading ones). Simple
relations between Δ ŕ, Δ ŕw,
Δr sin2θ w and
sin2ĝq w(m z) are derived.
These expressions bridge the overlineMS and on-shell renormalization
schemes and are very useful to compute γr and sin
2θw in thecase of large mw. The
mw- mz interdependence is expressed in two
equivalent ways: in terms of Δr and in terms of the parameter
p̂ = {m w2}/{m
z2cos2ĝq w(m
z) }. Applications of the expressions derived in the paper
are illustrated numerically.
From phenomenological and field-theoretical considerations on photon
mass, we first show that photon is not limited to being massless at the
present stage. Next we illustrate a possibility of formulating a local
field theory for massive photons coupled with nonconserved currents,
while we cannot formulate it for massless photons.
The Fermilab 15-ft bubble chamber, filled with a heavy neon-hydrogen mix, was exposed to a narrow-band ${$\nu${}}_{$\mu${}}$ beam. Based on the observation of 830 charged-current ${$\nu${}}_{$\mu${}}$ interactions, the cross section was found consistent with a linear rise with the neutrino energy in the interval $10 \mathrm{GeV}<~{E}_{$\nu${}}$\lesssim${}240 \mathrm{GeV}$. The average slope was determined to be $\frac{{$\sigma${}}_{$\nu${}}}{{E}_{$\nu${}}}=(0.62\ifmmode\pm\else\textpm\fi{}0.05)\ifmmode\times\else\texttimes\fi{}{10}^{$-${}38}$ ${\mathrm{cm}}^{2}$ ${\mathrm{GeV}}^{$-${}1}$.
Eichten et al. summarize the motivation for exploring the 1-TeV (=1012 eV) energy scale in elementary particle interactions and explore the capabilities of proton-(anti)proton colliders with beam energies between 1 and 50 TeV. The authors calculate the production rates and characteristics for a number of conventional processes, and discuss their intrinsic physics interest as well as their role as backgrounds to more exotic phenomena. The authors review the theoretical motivation and expected signatures for several new phenomena which may occur on the 1-TeV scale. Their results provide a reference point for the choice of machine parameters and for experiment design.
We report the most sensitive direct upper limit set on the mass mν of the electron antineutrino. Our measurements of the shape of the β decay spectrum of free molecular tritium yield, under the assumption of no new physics other than that of mass, a central value for mν2 of -147±68±41 eV2, which corresponds to an upper limit of 9.3 eV (95% confidence level) on mν. The result is in clear disagreement with a reported value of 26(5) eV.
We present complete calculations for basic observables at the SLC/LEP e+e− colliders: the Z0 cross sections, line shape and width, forward-backward and polarizat asymmetries effects of experimental cuts are explored. Special emphasis is placed on the polarization asymmetry, a highly sensitive measure of electroweak couplings and of the presence of heavy particles in virtual loops. The calculations were performed using a new, more efficient Monte Carlo method, which is also discussed.
The polarization parameters for the π++p→K++∑+ reaction have been measured at 13 laboratory momenta between 1490 and 2069 MeV/c in the angular range of with higher statistics than previous experiments. In general, the present results agree well with the results at the Rutherford Appleton Laboratory. It is found, however, that there exist small but systematic differences which can be attributed to certain coefficients in Legendre expansions. The physical significance of these differences is discussed.
We report an improved measurement of the inverse muon decay process, νμ+e→μ−+νe, at the Fermilab Tevatron. The rate of this reaction with respect to the νμ-N charged current interaction is measured to be (0.1245±0.0057(stat.)±0.0031 (sys.)) × 10−2. The measurement confirms the standard model predictions for the Lorentz structure of the weak current, the helicity of the neutrino, and the energy dependence of the cross section.
We present a comparison of a Monte Carlo simulation of the D0 Transition Radiation Detector with the data obtained with a prototype. The X-ray production is calculated taking into account the irregular distribution of the gaps between the foils of the radiator. The delta rays are simulated by using the cluster energy deposition spectrum given by the photoabsorption ionisation model. Space charge effects in the X-ray detector are important at normal incident angle, and have been included in the calculations.The Monte Carlo results reproduce the experimental pion rejection at the three angles at which the data have been taken.
We numerically study the regularization dependence of the upper bound on the Higgs-particle mass MH(phys) by varying the lattice type and interaction. Computing fπ and λr where the scalar mass is ∼ 1, we find the bound MH(phys)<620 GeV. However, there is a small but systematic increase in the bound as the coordination number of the lattice increases. Hence, it is not meaningful to quote error estimates on such bounds.
We calculate the one-loop electroweak radiative corrections to the longitudinal polarization asymmetry Apol and forward-backward asymmetry AFB both on and off Z0 resonance in a renormalization scheme which uses alphae.m.(0), MZ, MH, Mfermions and taumu (the muon decay lifetime) as input data. We find that their values change dramatically (an order of magnitude) at the Z0 resonance (q2 = -MZ2) depending on the precise value of Mz. Sufficiently accurate experiments may be able to set upper limits to the top quark or Higgs' masses and would provide definitive tests of the standard model at the one-loop level.
We consider radiative corrections to the parameter S characterizing ``oblique'' corrections to electroweak interactions from representations of electroweak interactions which preserve a custodial SU (2) symmetry. Our primary goal is to demonstrate that the contribution to S can take either sign. We consider two general cases, one with scalars and one with fermions. The most interesting example is scalar representations, which we will show can quite generally a negative contribution to S. For the class of fermion representations we consider, S can also be negative, although larger mass splittings between custodial SU (2) representations are required. Junior Fellow, Harvard Society of Fellows.
We have studied the beta spectrum of 14C using a germanium detector containing a crystal with 14C dissolved in it. We find a feature in the beta spectrum 17 keV below the end point which can be explained by the hypothesis that there is a heavy neutrino emitted in the beta decay of 14C with a mass of 17+/-2 keV and an emission probability of (1.40+/-0.45+/-0.14)%.
The analytic continuation relation found in the non-singlet structure of the processes e+h-->e-X and e-e+-->hX up to the next-to-the-leading-logarithm approximation, is shown to be true also for the singlet case. This relation is used to find the two-loop anomalous dimensions for the singlet time-like cut vertices from the anomalous dimension of the singlet space-like cut vertices. We give also the singlet time-like coefficient functions.
We suggest a method of searching for small violations of the Pauli principle. It is based on extracting and counting atoms with wrong (excessive) filling of the electron shells. Our estimates show that this approach proves to be several orders of magnitude more effective than the search for Pauli-forbidden X-ray transitions in NaJ (Tl) crystal.
We use dispersion relations to calculate the nucleon from factor of the scalar operator uu+dd and show that the corresponding mean square radius is remarkably large.
The study and the optimalisation of scintillation counters consisting of R1668 (R1398 with quartz window) photomultipliers and BaF2 crystals were carried-out in order to construct a 96 counter ring for time-of-flight positron tomography. The photoelectron yield measured for CsF and BaF2 crystals permitted us to estimate the photoelectron collection efficiency at different light wavelengths for R1668 photomultiplier in relation to the XP2020Q. This experiment, and the time resolution study, showed that at present the ability of R1668 photomultiplier for timing with BaF2 crystals is limited by a poor collection of photoelectrons produced by UV light. It was shown that a certain modification of the voltage between D1 and D2 dynodes improves the time resolution by 10%. A comparison of BaF2 crystals of different shapes showed that pyramidal cut crystal with a small opening angle equal to 1° ensures both a high detection efficiency and a good time resolution for 511 keV gamma-rays. The best time resolution equal to 330 ps and the typical one equal to 350 ps were achieved with two counters for time-of-flight positron tomography.
The coupling constant of the charged pions to nucleons is extracted from a partial-wave analysis of antinucleon-nucleon scattering data below {ital p}{sub lab}=950 MeV/{ital c}. For the value at the pion pole we find {ital f}{sub {ital c}}²=0.0751{plus minus}0.0017 or equivalently {ital g}{sub {ital c}}²=13.6{plus minus}0.3. This result is in agreement with the value found in the recent VPI SU analysis of Ï{ital N} scattering data. Comparing with the neutral-pion coupling constant as determined in the Nijmegan phase-shift analysis of proton-proton scattering data, we see no evidence for a charge dependence of the pion-nucleon coupling constants.
Neutrinos from the decay of B-8 in the sun have been observed in the Kamiokande-II detector. Based on 450 days of data for the time period January 1987 through May 1988, the measured flux obtained from data with E(e) of not less than 9.3 MeV is 0.46 + or - 0.13(stat.) + or - 0.08 (syst.) of the value predicted by the standard solar model. Within experimental errors, the Kamiokande-II value is in agreement with the corresponding value obtained by the Cl-37 radiochemical detector in essentially the same time period.
The quark mixing matrix (Kobayashi-Maskawa matrix) is expanded in powers of a small parameter lambda equal to thetac=0.22. The term of order lambda2 is determined from the recently measured B lifetime. Two remaining parameters, including the CP-nonconservation effects, enter only the term of order lambda3 and are poorly constrained. A significant reduction in the limit on ε'ε possible in an ongoing experiment would tightly constrain the CP-nonconservation parameter and could rule out the hypothesis that the only source of CP nonconservation is the Kobayashi-Maskawa mechanism.
The ${\overline{$\nu${}}}_{$\mu${}}$ charged-current total cross section has been measured with the Fermilab 15-ft bubble chamber plus the external muon identifier and internal "picket fence." Beam monitoring information used for the flux calculation was obtained from Blair et al., whose detector operated in the same dichromatic beam. The present result, averaged over ${\overline{$\nu${}}}_{$\mu${}}$ energies from 5 to 250 GeV, is $\frac{$\sigma${}}{E}=(0.340\ifmmode\pm\else\textpm\fi{}0.019\ifmmode\pm\else\textpm\fi{}0.022)\ifmmode\times\else\texttimes\fi{}{10}^{$-${}38}$ ${\mathrm{cm}}^{2}$/(GeV nucleon) for an isoscalar target.
We have carried out fits to the energy dependence of the P11 partial-wave amplitude as obtained in two different single-energy analyses of pi-N scattering data. Data on inelastic cross sections were also used. The fits used an analytic approximation to the coupled-channel amplitudes suggested by the Dyson equations. From each set of partial-wave data, two resonances were obtained, at roughly 1470 and 1700 MeV. Each of these resonances is associated with a cluster of poles on the Riemann surface.
I discuss the S- and T-parameters introduced by Peskin and Takeuchi to characterize the “oblique” radiative corrections to the electroweak interactions. Following Golden and Randall, and Holdom and Terning, I re-interpret these parameters in an effective field theory language. I hope to draw attention to the fact that the effective field theory framework is not only simpler and more transparent, but it actually provides information about the corrections that goes beyond perturbation theory. I illustrate the power of this approach by showing that it automatically implements the “resummation” of the quadratic mt dependence in the oblique corrections conjectured by Consoli et al. I also show how to incorporate (or “resum”) all the logarithmic dependence on mH and mt. I also comment briefly on the non-oblique corrections. In particular, I identify all the sources of leading mt2-dependence in the low-energy theory
Research supported in part by the National Science Foundation under grants PHY-8714654 and PHY82-17853, supplemented by funds from the National Aeronautics and Space Administration.
We review determinations, via experiment, of the strong coupling of QCD, alphas. In almost every case we use the results of perturbative QCD to make the necessary extraction from data. These include scaling violations of deep inelastic scattering, e+e- annihilation experiments (including quarkonium decays) and lepton pair production. Finally estimates for Lambda from lattice calculations are listed.
The theory of neutrino mixing and neutrino oscillations, as well as the properties of massive neutrinos (Dirac and Majorana), are reviewed. More specifically, the following topics are discussed in detail: (i) the possible types of neutrino mass terms; (ii) oscillations of neutrinos (iii) the implications of CP invariance for the mixing and oscillations of neutrinos in vacuum; (iv) possible varieties of massive neutrinos (Dirac, Majorana, pseudo-Dirac); (v) the physical differences between massive Dirac and massive Majorana neutrinos and the possibilities of distinguishing experimentally between them; (vi) the electromagnetic properties of massive neutrinos. Some of the proposed mechanisms of neutrino mass generation in gauge theories of the electroweak interaction and in grand unified theories are also discussed. The lepton number nonconserving processes ..mu -->..e..gamma.. and ..mu -->..3e in theories with massive neutrinos are considered. The basic elements of the theory of neutrinoless double-..beta.. decay are discussed as well. Finally, the existing data on neutrino masses, oscillations of neutrinos, and neutrinoless double-..beta.. decay are briefly reviewed. The main emphasis in the review is on the general model-independent results of the theory. Detailed derivations of these are presented.
Accelerator mass spectrometry was used to test the validity of the Pauli exclusion principle for atomic electrons. Limits for the concentration of anomalous atoms where three electrons are occupying the K shell thus violating the Pauli exclusion principle were obtained. In the case of anomalous 20Ne atoms, a limit of 20Ne/20Ne
We have made a search for anomalous X-ray arising from a small violation of the Pauli exclusion principle in current carrying cooper. No such signal was found. From a minimal set of assumptions we conclude that the probability that a new electron introduced into cooper would form a mixed symmetry state with respect to the electrons already present in the copper sample, thus violating the Pauli principle, is less than 1.7 × 10-26.
An extensive review of the quark model and its implications is given. Among the topics considered are gauge invariance, QCD, charm particles, QED, flavor, conservation laws, and mass formulas. (AIP)
In view of the almost established triviality of varphi4 in four dimensions it is conjectured that the mass of the Higgs particle in the minimal model is bounded by an amount that can be estimated without the knowledge of the physics at shorter distances. A possible numerical experiment which could give a nonperturbative estimate for the bound is proposed.
From 12000 charged-current ${$\nu${}}_{$\mu${}}$ D events obtained in an exposure of the Fermilab 15-ft bubble chamber to a high-energy wide-band neutrino beam, the absolute neutrino flux is determined using the reaction ${$\nu${}}_{$\mu${}}n$\rightarrow${}{$\mu${}}^{$-${}}p$. For the total charged-current cross section, ${$\sigma${}}_{t}=k{E}_{$\nu${}}$, $k=(0.68\ifmmode\pm\else\textpm\fi{}0.04\ifmmode\pm\else\textpm\fi{}0.10)\ifmmode\times\else\texttimes\fi{}{10}^{$-${}38}$ ${\mathrm{cm}}^{2}$/GeV is obtained for ${E}_{$\nu${}}$ between 10 and 200 GeV. No clear energy dependence of the slope parameter $k$ is observed.
We employ a quark model with ingredients suggested by quantum chromodynamics to study strangeness-2 and-3 resonances. Predictions of the spectrum and decay couplings of such states are made based on previous studies of the nonstrange and strangeness-1 sectors.
A new upper bound ofmv < 13 eV at 95% CL has been obtained on the electron anti-neutrino mass. Thus results is based on a more than tenfold improvement in data relative to our previous measurements of the beta-spectrum in 3H decay, and its in conflict with the finite mass of 17
The positron spectrum from the reaction nue+p-->e++n was measured at a distance of 64.7 m from the core of the Gösg en power reactor. These new data, combined with those of previous measurements performed under otherwise identical conditions at 37.9 m and 45.9 m, were analyzed in terms of two-neutrino oscillations of the type nue x. No evidence for neutrino-oscillations was found. In particular, the oscillation parameter region favored by an experiment at the Bugey reactor is not supported by the data presented here. Present address: University of Neuchâtel, CH-2000 Neuchâtel, Switzerland.
The components of the transverse polarization of the positrons in the decay mu+-->e+nunu have been measured as a function of the positron total energy. Their energy average is=0.016+/-0.023, =0.007+/-0.023 (statistical plus systematic errors). The energy dependence of PT1 and PT2 yields the mu decay parameters alpha/A, beta/A (with their linear combination eta=(alpha-2beta)/A) and alpha'/A, beta'/A, respectively. In an analysis based only on the most general, local, derivative-free four-fermion point interaction, and including all corresponding measurements, the complete set of parameters describing muon decay is determined for the first time.
We describe a simple generalization of the Peccei-Quinn mechanism which eliminates the strong CP problem at the cost of a very light, very weakly coupled axion. The mechanism requires no new fermions and is easily implemented in grand unified theories. Research supported by the National Science Foundation under Grant #PHY80-19754.
The total cross sections for νμn and νμp charged-current interactions and their ratio R=σT(νn)/σT(νp) have been measured as a function of neutrino energy from 0.4 to 10 GeV. The experiment is performed using the BNL 7-foot deuterium bubble chamber exposed to the Alternating Gradient Synchrotron wide-band neutrino beam. The absolute values of the cross sections are normalized to the quasielastic scattering (νμn→μ-p) cross section. Above 1.6 GeV the data are consistent with the quark-parton model. We find that σT(νn)/Eν=(1.07±0.05)×10-38, σT(νp)/Eν=(0.54±0.04)×10-38, and σT(νN)/Eν=(0.80±0.03)×10-38 cm2/GeV for 〈Eν〉=3.2 GeV, and R=1.95±0.10 for 〈Eν〉=3.7 GeV.
We have analyzed a recent observation of Ds+→ηπ+ and Ds+→η’π+ in two theoretical schemes for charm→two-body hadron decays.
The implications of precision Z-pole, W-mass, and weak-neutral-current data for SU(2)×U(1) models are described. Within the minimal model one finds sin2θ̂W(MZ)=0.2334±0.0008 in the modified minimal subtraction scheme or sin2θW≡1-MW2/MZ2=0.2291±0.0034 in the on-shell scheme, where the uncertainties include the mt and MH dependence. The top-quark mass is predicted to be 124-34-15+28+20 GeV, where the second uncertainty is from MH, with mt<174(182) GeV at 90 (95)% C.L. For the first time subleading effects and vertex corrections allow a significant separation of mt and ρ0 in models with a nonminimal Higgs structure. Allowing arbitrary mt and Higgs representations one obtains sin2θ̂W(MZ)=0.2333±0.0008, ρ0=0.992±0.011, and mt<294(310) GeV. The implications of these results for ordinary and supersymmetric grand unified theories are considered. Supersymmetric theories with a grand desert between the supersymmetry and unification scales are in striking agreement with data for MSUSY in the MZ-1 TeV range. Ordinary grand unified theories breaking to the standard model in more than one step are also discussed.
We present a general theory of leptonic decays which consistently incorporates the possibility of nonzero neutrino masses and associated lepton mixing. We calculate the differential decay distribution d2Γ/dEbd cosθ and the lb polarization for "the" decay la→νlalbν̅ lb, i.e., in general the incoherent sum of decays la→νilbν̅ j into all allowed mass eigenstates νi and ν̅ j. Expressions are also given for the average quantities 〈cosθ〉(Eb), 〈cosθ〉 (integrated over Eb), 〈Eb〉(θ), and 〈Eb〉 for individual (i,j) decay modes and the observed sum. The total rate for massive-neutrino modes is calculated for the relevant experimental cases. These results are applied to analyze what the observable characteristics of massive neutrinos and lepton mixing would be in leptonic la decay. We show that dΓ/dEb would in general contain kinks at intermediate energies and carry out a search for these in existing μ and τ decay data. We further show that the conventional determination of the Lorentz structure of weak leptonic couplings via measurement of the spectral parameters ρ, η, ξ, and δ is not applicable in the presence of massive neutrinos and lepton mixing; a deviation of the observed parameters (with radiative corrections extracted) from their conventional V-A values could be caused either by non-(V-A) Lorentz structure or by massive-neutrino decay modes and lepton mixing. Thus, past measurements of the spectral parameters yield information only on the combined effects of the underlying Lorentz structure of the couplings and on possible neutrino masses and mixing, but not on either of these in isolation. The appropriate generalized formalism for the analysis of Lorentz structure in leptonic decays is given, and a quantitative study is performed of the effects of neutrino masses and mixing on the spectral parameters. We propose methods to distinguish between these effects and those due to possible non-(V-A) Lorentz structure; these methods can be applied in a reanalysis of old μ and τ decay data, and can serve as part of a generalized framework for the analysis of forthcoming data. Within the context of the standard electroweak theory we apply our results to existing data to obtain new upper bounds on the possible contributions of massive neutrino modes. Finally, we determine the optimal ways in which, and the corresponding sensitivity with which, forthcoming experiments on μ and τ decay can search for massive neutrinos and lepton mixing.
In this paper and the others in the series we present a generalized theory of weak leptonic and semileptonic decays which consistently incorporates the possibility of nonzero neutrino masses and associated lepton mixing. In the present work we give an analysis of the leptonic decays of charged pseudoscalar mesons within the generalized theory. The charged-lepton spectrum from such a decay is shown to consist not just of a single line, but instead a discrete set of lines. We state the precise meaning of neutrino-mass limits. The analysis leads to a new and very sensitive test for neutrino masses and mixing and to a corresponding proposal for new experiments on πl2 and Kl2 decays. This test involves a measurement of the charged-lepton momentum or energy spectrum and is capable of yielding the mass and weak coupling coefficient, individually, for each neutrino that can occur in such a decay. The test is applied to existing data to derive correlated bounds on these quantities. The use of this test as a low-energy probe of the number of lepton generations is proposed. We also discuss an extended spectral test involving measurement of the charged-lepton polarization. Next, we give an analysis of the constraints arising from the ratios B(M+→e+νe)/B(M+→μ+νμ), where M=π or K, which takes proper account of the experimental cuts that are used to define e+``νe'' and μ+``νμ'' events. Finally, the general theory of the leptonic decays of heavy 0- mesons is presented, together with tests for neutrino masses and mixing which make use of the momentum spectra, integrated e/μ yields, and possible decays of sufficiently heavy neutrinos.
We consider the effect of free-streaming axion emission on numerical models for the cooling of the newly born neutron star associated with SN 1987A. We find that for an axion mass of greater than ∼10-3 eV, axion emission shortens the duration of the expected neutrino burst so significantly that it would be inconsistent with the neutrino observations made by the Kamiokande II and Irvine-Michigan-Brookhaven detectors. However, we have not investigated the possibility that axion trapping (which should occur for masses ≥0.02 eV) sufficiently reduces axion emission so that axion masses greater than ∼2 eV would be consistent with the neutrino observations.
We derive formulas for τμ, mW, and mZ in the SU(2)L×U(1) theory which are valid through O(α2lnm), where m is a generic fermion mass; terms of O(αmμ2/mW2) are neglected. The emphasis of the analysis is on the role played by fermion mass singularities. The final results are very simple: the radiative correction of the local V-A theory [through O(α2ln(mμ/me))] factors out and the heavy particles induce a renormalization that can be expressed as an elementary function of the corresponding O(α) contribution slightly modified by fourth-order vacuum-polarization effects.
Total cross sections, angular, and mass distributions for the reaction π-p→π0π0n have been measured for pπ-(lab)=7–140 MeV/c above threshold. The threshold amplitude was used to determine a value for the chiral-symmetry-breaking parameter, ξ, of -0.98±0.52. The ππ scattering lengths aI for isospin I=0 and 2 are derived from this result, together with a current-algebra sum rule. The results are a0=(0.207±0.028)mπ-1 and a2=(-0.022±0.011)mπ-1. These values are consistent with chiral symmetry broken by the Weinberg ππ interaction and the effects of the f0(975) scalar meson.