Physics Letters B

Published by Elsevier
Online ISSN: 0370-2693
Publications
Article
Calculations of the longitudinal and transverse momentum distributions for 3H production at large momentum in alpha-12C collisions near 2 A GeV are compared to experiment. Triton exchange and final-state interactions are shown to represent large corrections to the impulse approximation for proton knockout. A method for calculating interference effects for inelastic fragmentation is discussed. Good agreement with experiment is found using a phenomenological overlap function for 3H-p successful in describing 3H production in pion-induced reactions. Comparisons to momentum distributions obtained through (p, 2p) and (e, ep) reactions on 4He are made.
 
Article
Mean multiplicities of pi+ and pi- in 4He collisions with C, Cu, and Pb at 200, 600, and 800 MeV/u, and with C and Pb at 400 MeV/u have been measured using the large solid angle detector Diogene. The independence of pion multiplicity on projectile incident energy, target mass and proton multiplicity is studied in comparison with intra-nuclear cascade predictions. The discrepancy between experimental results and theory is pointed out and discussed.
 
A schematic drawing of the laser–microwave–laser method. The dashed arrows indicate the laser transitions between the SHF levels of the radiative decay-dominated state (n,L)=(36,34) and the Auger decay-dominated state (n,L)=(37,33) of 
. The wavy lines illustrate the microwave-induced transitions between the SSHF levels of the long-lived state.
Part of the analog delayed annihilation time spectrum (ADATS) with the two laser-stimulated annihilation peaks against the exponentially decaying background of the metastable cascade. T denotes the delay time between the two laser pulses. The photomultipliers are gated off during the initial 
 pulse arrival [14]. Thus the prompt peak is cut off and only the annihilations due to the metastable state depopulation are recorded.
Drawing of the central part of the experimental setup, a cross-section of the cryostat.
Laser resonance profile for the (n,L)=(36,34) state of 
, displaying the two laser transitions 
 and 
 between the HF states of the parent and the daughter state, at a target pressure of 250 mbar. The peaks are fitted with four Voigt functions referring to the four “allowed” E1 transitions between the SHF states of the parent state (refer to Fig. 1). The arrows indicate the corresponding theoretical transition frequencies.
Scan over the microwave frequency for two of the four SSHF transitions for the (n,L)=(36,34) state of 
, at a target pressure of 250 mbar. Each transition is fitted with Eq. (2) (solid lines). The frequencies of the measured transitions are 11.12559(14) GHz and 11.15839(18) GHz. The dashed curve shows a simulation using collision rates obtained from comparison between experiment and simulation.
Article
We report on the first experimental results for microwave spectroscopy of the hyperfine structure of p¯3He+. Due to the helium nuclear spin, p¯3He+ has a more complex hyperfine structure than p¯4He+, which has already been studied before. Thus a comparison between theoretical calculations and the experimental results will provide a more stringent test of the three-body quantum electrodynamics (QED) theory. Two out of four super-super-hyperfine (SSHF) transition lines of the (n,L)=(36,34) state were observed. The measured frequencies of the individual transitions are 11.12559(14) GHz and 11.15839(18) GHz, less than 1 MHz higher than the current theoretical values, but still within their estimated errors. Although the experimental uncertainty for the difference of these frequencies is still very large as compared to that of theory, its measured value agrees with theoretical calculations. This difference is crucial to be determined because it is proportional to the magnetic moment of the antiproton.
 
Article
Proton-proton small angle correlations have been measured in neon-nucleus collisions, using the 4 pi detector Diogene, at 400 and 800 MeV per nucleon incident energies. Values of the size of the emitting region are obtained by comparison with the Koonin formula, taking into account the biases of the apparatus. The dependence of the density on target mass and incident energy is also analysed.
 
Article
We measured the charge of about 35000 projectile fragments with Z > or = 5e produced by 14.5 GeV/nucleon and 200 GeV/nucleon 16O beams in a Pb target using CR39 plastic nuclear track detectors. A minimum track length of 3 mm in the detector without nuclear interaction was required. No evidence for fragments carrying a fractional charge was found.
 
OPE calculated in terms of the pole mass (left) and the 
 mass (right) of the c quark. First line: spectral densities; second line: corresponding sum-rule estimates for 
. A constant effective continuum threshold 
 is fixed in each case separately by requiring “maximal stability” of the extracted decay constant. As the result, 
 turns out to be different in the two schemes. Bold line – total result, solid line (black) – O(1) contribution; dashed line (red) – 
 contribution; dotted line (blue) – 
 contribution; dash-dotted line (green) – power contributions. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this Letter.)
Dual mass (a) and dual decay constant (b) of the D meson obtained using different Ansätze for the effective continuum threshold 
(3.2) and fixing all thresholds according to (3.3). Results for 
, 
, and central values of the other relevant parameters are presented. (c) Dual decay constant of the D meson vs. 
 for 
 and central values of the other OPE parameters. The integer n = 0,1,2,3 is the degree of the polynomial in our Ansatz (3.2) for 
: dotted line (red) – n = 0; solid line (green) – n = 1; dashed line (blue) – n = 2; dash-dotted line (black) – n = 3. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this Letter.)
(a) Distribution of 
 obtained by the bootstrap analysis of the OPE uncertainties. Gaussian distributions for all OPE parameters but μ with corresponding errors as given in (2.1) are employed. For μ we assume a uniform distribution in the range 1 GeV < μ < 3 GeV. (b) Summary of findings for 
. Lattice results are from [10,11] for two dynamical light flavors (
) and from [12,13] for three dynamical flavors (
). The triangle represents the experimental value from PDG [14]. The estimate obtained with the constant threshold includes the OPE uncertainty only; for the τ-dependent QCD-SR result the error shown is the sum of the OPE and systematic uncertainties in (3.5), added in quadrature.
Same as Fig. 2 but for the 
 meson.
(a) Distribution of 
 obtained by the bootstrap analysis of the OPE uncertainties. Gaussian distributions for all OPE parameters but μ with corresponding errors as given in (2.1) are employed. For μ we assume a uniform distribution in the range 1 GeV < μ < 3 GeV. (b) Summary of findings for 
. Lattice results are from [10,11] for two dynamical light flavors (
) and from [12,13] for three dynamical flavors (
). The triangle represents the experimental value from PDG [14]. The estimate obtained with the constant threshold includes the OPE uncertainty only; for the τ-dependent QCD-SR result the error shown is the sum of the OPE and systematic uncertainties in (3.7), added in quadrature.
Article
We present a sum-rule extraction of the decay constants of the charmed mesons D and Ds from the two-point correlator of pseudoscalar currents. First, we compare the perturbative expansion for the correlator and the decay constant performed in terms of the pole and the running MS¯ masses of the charm quark. The perturbative expansion in terms of the pole mass shows no signs of convergence whereas reorganizing this very expansion in terms of the MS¯ mass leads to a distinct hierarchy of the perturbative expansion. Furthermore, the decay constants extracted from the pole-mass correlator turn out to be considerably smaller than those obtained by means of the MS¯-mass correlator. Second, making use of the OPE in terms of the MS¯ mass, we determine the decay constants of both D and Ds mesons with an emphasis on the uncertainties in these quantities related both to the input QCD parameters and to the limited accuracy of the method of sum rules.
 
Article
We show the equivalence of semi-classical solutions to optical model coupled-channel equations derived from Watson's form of the nucleus-nucleus multiple-scattering series to the Glauber multiple-scattering series. A second-order solution to the semi-classical coupled-channel elastic amplitude is shown to be nearly equivalent to a second-order optical-phase-shift approximation to the Glauber amplitude if the densities of all nuclear excited states are approximated by the ground-state density. Using the Jastrow method to model the two-body density we find an average excited-state density to be of negligible importance in the double-scattering region of alpha-alpha scattering.
 
The average number of Gribov copies as a function of lattice extension (left panel) and volume (right panel) in two, three, and four dimensions at a = 0.22 fm, distinguished by their value of tr D. At finer a at fixed physical volume the number of copies increases further [13]. All lines drawn to guide the eye. Lattice volumes 
 are for d = 2, 3, and 4 from the sets {10,18,26,34}, {8,14,20,26}, and {6,10,14}, respectively, throughout. A fit of type 
 gives an e of approximately 16, 4.4, and 2.9 fm in 2, 3, and 4 dimensions, respectively.
The distribution of tr D compared to b(280 MeV,∞) on a 203 lattice at a = 0.22 fm. The left panel shows for an example configuration that for each distinct Gribov copy, identified by differing tr D values, also the b values differ. 22 copies have been generated for this configuration, with 10 distinct Gribov copies found, one peak being hidden by foreground peaks. The right panel shows the distribution for 1450 configurations.
The gauge corridor for different lattice extensions (left panel) and volumes (right panel). For each volume 〈min b(min p,μ)〉 and 〈max b(min p,μ)〉 are shown, where min p is the smallest non-zero momentum on each lattice, and μ is set to ∞ for two and three dimensions, yielding G(μ)=1, and to μ = 2 GeV in four dimensions.
The gluon propagator (left panel) and the ghost dressing function (right panel) for various gauges from a 203 lattice at a = 0.22 fm. The minimal Landau gauge is described in [9], and the absolute Landau gauge in [3]. The min B and max B gauges select the minimum and maximum possible value of B, respectively, and are described in the text. The inverse Landau gauge maximizes (3) over the set of all local minima on the residual gauge orbit [15].
Article
Gauge fixing in the non-perturbative domain of non-Abelian gauge theories is obstructed by the Gribov-Singer ambiguity. To compare results from different methods it is necessary to resolve this ambiguity explicitly. Such a resolution is proposed using conditions on correlation functions for a family of non-perturbative Landau gauges. As a consequence, the various results available for correlation functions could possibly correspond to different non-perturbative Landau gauges, discriminated by an additional non-perturbative gauge parameter. The proposal, the necessary assumptions, and evidence from lattice gauge theory calculations, are presented in detail.
 
Form factors Q2FPγ (P=η,η′) vs Q2: experimental data from Cello and Cleo [1,2] (black dots), BaBar [5] (red squares), and the data borrowed from the time-like region [3] (green triangles). Dashed lines—the results from [14] which obey the factorization theorem at Q2→∞; solid lines—our fits for rq(I=0)=rs=0.05 GeV2. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this Letter.)
Form factor Q2Fπγ vs Q2: experimental data from Cello, Cleo [1,2] (black dots), BaBar [4] (red squares) and Belle [18] (blue triangles); dashed line—the results from [14] which obey the factorization theorem at Q2→∞. Solid lines—our fits. In the fit to the Belle data, the value for r is taken identical to the one used for the nonstrange component of Fηγ and Fη′γ in Fig. 1. The grey shaded region corresponds to the range 0.05 GeV2⩽rq(I=1)⩽0.17 GeV2. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this Letter.)
Article
The photon transition form factors of π, η and [Formula: see text] are discussed in view of recent measurements. It is shown that the exact axial anomaly sum rule allows a precise comparison of all three form factors at high-[Formula: see text] independent of the different structures and distribution amplitudes of the participating pseudoscalar mesons. We conclude: (i) The πγ form factor reported by Belle is in excellent agreement with the nonstrange [Formula: see text] component of the η and [Formula: see text] form factors obtained from the BaBar measurements. (ii) Within errors, the πγ form factor from Belle is compatible with the asymptotic pQCD behavior, similar to the η and [Formula: see text] form factors from BaBar. Still, the best fits to the data sets of πγ, ηγ, and [Formula: see text] form factors favor a universal small logarithmic rise [Formula: see text].
 
Energy spectrum of the kaonic 3He X-rays in coincidence with the K+K− events. The kaonic 3He 3d→2p transition is seen at 6.2 keV. Together with this peak, small peaks are seen, which are the kaonic atom X-ray lines produced by kaons stopping in the target window made of Kapton (polyimide), and the Ti Kα line at 4.5 keV.
X-ray energy spectra of the SDDs, where data of all the selected SDDs were summed: (a) data taken with the X-ray tube, and (b) data uncorrelated to the kaon production timing in the production data. The peak positions of the Ti, Cu, and Au fluorescence X-ray lines in figure (b) were used to determine the accuracy of the energy scale.
Time spectrum of the SDDs. The time difference between the K+K− coincidence and SDD X-ray hits was plotted. The peak region corresponds to the coincidence of the K+K− and X-ray events. A region from 2.9 μs to 4.6 μs was accepted as a timing window of the triple coincidences.
Timing spectrum of the two scintillators in the kaon detector. The time difference between the clock signals delivered by DAΦNE and the coincidence of the two scintillators is shown. The K+K− and MIPs coincidence events are marked in the figure. The regions marked with a rectangle were accepted as timing windows of the K+K− coincidence.
An overview of the experimental setup. The whole system was installed at the interaction point of DAΦNE.
Article
The first observation of the kaonic 3He 3d - 2p transition was made using slow K- mesons stopped in a gaseous 3He target. The kaonic atom X-rays were detected with large-area silicon drift detectors using the timing information of the K+K- pairs of phi-meson decays produced by the DAFNE e+e- collider. The strong interaction shift of the kaonic 3He 2p state was determined to be -2+-2 (stat)+-4 (syst) eV.
 
Article
A proposed duality between type IIB superstring theory on 9 × S1 and a conjectured 11D fundamental theory (“M theory”) on 9 × T2 is investigated. Simple heuristic reasoning leads to a consistent picture relating the various p-branes and their tensions in each theory. Identifying the M theory on 10 × S1 with type IIA superstring theory on 10, in a similar fashion, leads to various relations among the p-branes of the IIA theory.
 
Article
New data are presented on J/ψ→ωK+K− from a sample of 58M J/ψ events in the upgraded BES II detector at the BEPC. There is a conspicuous signal for f0(1710)→K+K− and a peak at higher mass which may be fitted with . From a combined analysis with ωπ+π− data, the branching ratio is <0.11 at the 95% confidence level.
 
Article
The supersymmetric Liouville equation is integrated explicitly. The general solutions are defined by four arbitrary functions. The gauge field potentials entering the representation of zero curvature are spanned by the elements of Lie superalgebra b(0,1).
 
Article
We derive a condition under which (0,2) linear sigma models possess a “left-moving” conformal stress tensor in cohomology (i.e. which leaves invariant the “right-moving” ground states) even away from their critical points. At the classical level this enforces quasihomogeneity of the superpotential terms. The persistence of this structure at the quantum level on the worldsheet is obstructed by an anomaly unless the charges and superpotential degrees satisfy a condition which is equivalent to the condition for the cancellation of the anomaly in a particular “right-moving” U(1) R-symmetry.
 
Article
We derive the moduli dependence of the one-loop gauge couplings for non-vanishing gauge background fields in a four-dimensional heterotic (0,2) string compactification. Remarkably, these functions turn out to have a representation as modular functions on an auxiliary Riemann surface on appropriate truncations of the full moduli space. In particular, a certain kind of one-loop functions is given by the free energy of two-dimensional solitons on this surface.
 
Article
It has recently been realized that a large class of Calabi-Yau models in which the VEV of the gauge connection is not set equal to the spin connection of the Calabi-Yau manifold are valid classical solutions of string theory. We provide some examples of three generation models based on such generalized Calabi-Yau compactifications, including models with observable gauge group SU (3) × SU (2) × U (1).
 
Article
Measurements were made at SLAC of the cross section for scattering 29 GeV electrons from carbon at a laboratory angle of 4.5°, corresponding to 0.03<x<0.1 and 1.3<Q2<2.7 GeV2. Values of R=σL/σT were extracted in this kinematic range by comparing these data to cross sections measured at a higher beam energy by the NMC collaboration. The results are in reasonable agreement with pQCD calculations and with extrapolations of the R1990 parameterization of previous data. A new fit is made including these data and other recent results.
 
(a) A hypothetical universe with all galaxies having the same handedness. Note that galaxies in one hemisphere would appear to us to be right-handed and in the opposite hemisphere left-handed. (b) A “typical” spiral galaxy from the SDSS. This one is defined as having right-handed “spin”. (c) A left-handed two-armed spiral galaxy.
Polar plot of net asymmetries 〈A〉 in 30° sectors in right ascension and slices in z. Segments with positive 〈A〉 are indicated in red and negative 〈A〉 in blue. The 〈A〉 for segments with <10 galaxies are not shown. The larger numbers near the periphery give the overall asymmetry for that sector; the black numbers in parentheses are the total number of spiral galaxies in the sector. The NGP is the north pole of our Galaxy, so that the left half of the plot corresponds roughly to the northern Galactic hemisphere. The black arrow shows the most probable dipole axis. Declinations between −19° and +60° were used.
(a) Spatial correlation of the spiral galaxies in the sample vs. 3D separation. The peaking for separations <20 Mpc/h is due to clustering. (b) The asymmetry of spiral galaxy spins vs. separation. The correlation extends out to separations ∼210 Mpc/h.
Variation of χ2–dof with αA for δA=32°. The xʼs are for axes at 90° to the best-fit axis.
Probability of obtaining a particular value of (dof–χmin2) for 4×105 samples of the 15,158 galaxies with randomized handednesses. The lowest χ2 from 100 axes randomly chosen within the SDSS survey was used. The arrow shows the value of χ2=13.356 for the actual handedness assignments for the best-fit axis at (αA,δA)=(217°,32°); the probability of finding that value or greater by chance is 7.9×10−4.
Article
A preference for spiral galaxies in one sector of the sky to be left-handed or right-handed spirals would indicate a parity violating asymmetry in the overall universe and a preferred axis. This study uses 15158 spiral galaxies with redshifts <0.085 from the Sloan Digital Sky Survey. An unbinned analysis for a dipole component that made no prior assumptions for the dipole axis gives a dipole asymmetry of -0.0408\pm0.011 with a probability of occurring by chance of 7.9 x 10-4. A similar asymmetry is seen in the Southern Galaxy spin catalog of Iye and Sugai. The axis of the dipole asymmetry lies at approx. (l, b) =(52{\deg}, 68.5{\deg}), roughly along that of our Galaxy and close to alignments observed in the WMAP cosmic microwave background distributions. The observed spin correlation extends out to separations ~210 Mpc/h, while spirals with separations < 20 Mpc/h have smaller spin correlations.
 
Generalized forward spin polarizability γ p 0 as a function of Q 2 for the full integral (closed circles), the measured portion of the integral (open circles) and Q 2 = 0 [44] (triangle). The systematic error on the measured (grey) and unmeasured (dark) contributions are indicated by bands. χPT calculations [17, 45] are shown along with MAID 2003 [46]. The data shown on the right are weighted by Q 6 /(16αM 2 ). Our parametrization of world data is also shown at moderate to high Q 2 .
Article
The spin structure functions g1 for the proton and the deuteron have been measured over a wide kinematic range in x and Q2 using 1.6 and 5.7 GeV longitudinally polarized electrons incident upon polarized NH3 and ND3 targets at Jefferson Lab. Scattered electrons were detected in the CEBAF Large Acceptance Spectrometer, for 0.05<Q2<5 GeV2 and W<3 GeV. The first moments of g1 for the proton and deuteron are presented – both have a negative slope at low Q2, as predicted by the extended Gerasimov–Drell–Hearn sum rule. The first extraction of the generalized forward spin polarizability of the proton is also reported. This quantity shows strong Q2 dependence at low Q2. Our analysis of the Q2 evolution of the first moment of g1 shows agreement in leading order with Heavy Baryon Chiral Perturbation Theory. However, a significant discrepancy is observed between the data and Chiral Perturbation calculations for , even at the lowest Q2.
 
Article
First data on coherent threshold π0 electroproduction from the deuteron taken by the A1 Collaboration at the Mainz Microtron MAMI are presented. At a four-momentum transfer of the full solid angle was covered up to a center-of-mass energy of 4 MeV above threshold. By means of a Rosenbluth separation the longitudinal threshold s wave multipole and an upper limit for the transverse threshold s wave multipole could be extracted and compared to predictions of Heavy Baryon Chiral Perturbation Theory.
 
Article
The EM form factor of the pion has been studied in the time-like region by measuring σ(e+e− → π+π−) normalized to σ(e+e− → μ+μ−). Results have been obtained for q2 down to the physical threshold.
 
Article
We report new precise measurements at the peak of the Δ+(1232) resonance at performed at the Mainz Microtron (MAMI). The new data are sensitive to both the electric (E2) and the Coulomb (C2) quadrupole amplitudes of the γ∗N→Δ transition. They yield precise quadrupole to dipole amplitude ratios: CMR=(−5.09±0.28stat+sys±model0.30)% and EMR=(−1.96±0.68stat+sys±model0.41)% for . The new results are in disagreement with Constituent Quark Model predictions and in qualitative agreement with models that account for mesonic contributions, including recent Lattice calculations. They thus give further credence to the conjecture of deformation in hadronic systems favoring the attribution of the origin of deformation to the dominance of mesonic effects.
 
Article
The correlations between charged particle multiplicitie produced in forward and backward pseudorapidity regions in pp̄ interactions have been measured with a 240 element scintillator hodoscope. The correlation coefficient and the variance of the difference of multiplicities in the two pseudorapidity regions were deterermined for . These results have been interpreted in terms of a cluster model of particle production.
 
Galaxy images (left) and the transforma- 
The peaks detected in the radial intensity 
Galaxy handedness asymmetry in different RA ranges
Article
A dataset of 126,501 spiral galaxies taken from Sloan Digital Sky Survey was used to analyze the large-scale galaxy handedness in different regions of the local universe. The analysis was automated by using a transformation of the galaxy images to their radial intensity plots, which allows automatic analysis of the galaxy spin and can therefore be used to analyze a large galaxy dataset. The results show that the local universe (z<0.3) is not isotropic in terms of galaxy spin, with probability P<5.8*10^-6 of such asymmetry to occur by chance. The handedness asymmetries exhibit an approximate cosine dependence, and the most likely dipole axis was found at RA=132, DEC=32 with 1 sigma error range of 107 to 179 degrees for the RA. The probability of such axis to occur by chance is P<1.95*10^-5 . The amplitude of the handedness asymmetry reported in this paper is generally in agreement with Longo, but the statistical significance is improved by a factor of 40, and the direction of the axis disagrees somewhat.
 
Article
A direction-sensitive dark matter search experiment at Kamioka underground laboratory with the NEWAGE-0.3a detector was performed. The NEWAGE- 0.3a detector is a gaseous micro-time-projection chamber filled with CF4 gas at 152 Torr. The fiducial volume and target mass are 20*25*31 cm3 and 0.0115 kg, respectively. With an exposure of 0.524 kgdays, improved spin-dependent weakly interacting massive particle (WIMP)-proton cross section limits by a direction-sensitive method were achieved including a new record of 5400 pb for 150 GeV/c2 WIMPs. We studied the remaining background and found that ambient gamma-rays contributed about one-fifth of the remaining background and radioactive contaminants inside the gas chamber contributed the rest.
 
Article
The emission of complex fragments (3⩽Z≲12) from reactions of 3He with natAg has been studied at bombarding energies of E = 480, 900, 1800, 2700 and 3600 MeV. Between 900 and 1800 MeV slopes of the fragment kinetic energy spectra at backward angles undergo a change in character, becoming much flatter; in addition, the Coulomb peak is found to broaden significantly and shift to lower energies. Power-law fits to the fragment charge distributions result in decreasing values of the exponent τ up to a bombarding energy of 1800 MeV; at this value and beyond, a constant value of τ=2.1±0.1 is observed. Elemental cross sections at the highest energy are found to increase by approximately two orders of magnitude relative to data near 100 MeV. The data suggest a change in reaction mechanism between incident energies of 900 and 1800 MeV.
 
Article
We present first measurements of total cross section differences ΔσT and ΔσL for a polarized neutron beam transmitted through a polarized proton target. Measurements were carried out at SATURNE II, at 0.63, 0.88, 0.98 and 1.08 GeV. The results are compared with ΔσL data points deduced from p-d and p-p transmission experiments, and with phase shift analyses predictions. The present results together with the corresponding pp data yield two of the three spin dependent forward scattering amplitudes for isospin I=0.
 
Article
We summarize the results obtained in the UA1 experiment on the production of bottom quarks in proton-antiproton collisions at √s=0.63 TeV. Independent muon data samples are used to determine the bottom quark production cross section in different transverse momentum ranges from 6 to 30 GeV. A recent theoretical calculation to O(αs3) of the inclusive bottom quark transverse momentum spectrum in hadronic collisions shows reasonable agreement with the data. We extrapolate the integral PT distribution to PT=0 and in rapidity to estimate the total cross section forthe production of bottom quark pairs. Assuming the shape in PT and rapidity given by the O(αs3) calcultaion, we obtain .
 
Article
A low-energy muon neutrino beam was used to illuminate two similar fine-grained neutrino detectors placed at 123 m and 903 m from the beginning of the neutrino source. The fiducial masses of the “close” and the “far” detector were about 36 tons and 120 tons respectively. The average energy of the selected neutrino events was 1.5 GeV. Data were recorded for an integrated flux of about 1019 protons. Quasielastic charged current events initiated by νe's have been searched for and an upper limit of 2.7%, at 90% confidence level, is obtained for the fraction of νμ's transformed into νe's. For complete mixing this correspnds to a limit Δm2 ⩽ 0.20 eV2 for the transition νμ → νe and to a minimum value of the mixing parameter sin22θ = 0.04. In the same data sample we compared the rates in the two detectors of νμ-initiated charged current events, mainly of quasielastic type: we conclude that oscillations of νμ's to ντ's, and possibly heavier neutrinos, do not appear. For complete mixing the limit in this case is Δm2 ⩽ 0.29 eV2.
 
Article
The parity nonconserving spin rotation of neutrons in the 0.734-eV p-wave resonance of $^{139}La$ was measured with the neutron transmission method. Two optically polarized $^3He$ cells were used before and behind a a 5-cm long $^{139}La$ target as a polarizer and an analyzer of neutron spin. The rotation angle was carefully measured by flipping the direction of $^3He$ polarization in the polarizer in sequence. The peak-to-peak value of the spin rotation was found to be $ (7.4 \pm 1.1) \times 10^{-3} $ rad/cm which was consistent with the previous experiments. But the result was statisticallly improved. The s-p mixing model gives the weak matrix element as $xW = (1.71 \pm 0.25)$ meV. The value agrees well with the one deduced from the parity-nonconserving longitudinal asymmetry in the same resonance.
 
Article
Differential cross sections and analyzing powers for the elastic scattering of 800 MeV polarized protons from 40,42,44,48Ca are reported. A first-order, spin-dependent KMT optical potential analysis is presented from which the rms radii of the neutron densities are deduced. A comparison of these results with other determinations and with various theoretical predictions is given.
 
(a) Number of pp→ppπ0 events in the interval 8.9°<θppcm<13° as a function of Epp; (b) The same data corrected for acceptance and detection efficiency and presented as differential cross sections. Only statistical errors are shown. The curve results from passing the Migdal–Watson function |T(Epp)|2 of Eq. (1), multiplied by phase space, through a Monte Carlo simulation of the ANKE apparatus and normalising the predictions to the summed experimental histogram. Similar results are found for the other angular intervals.
The measured pp→{pp}sπ0 differential cross section for Epp<3 MeV as a function of cos2(θπcm). The curve is a straight–line fit to the data.
Scatter plot of the magnitudes of the momenta of two charged particles detected in the FD. The selection procedure introduces a slight bias as to which particle is called “1”, but this does not affect the subsequent analysis.
Distribution of acceptance-corrected pp→{pp}sπ0 events with Epp<3 MeV over cosθp∗, where θp∗ is the angle between relative pp momentum in the diproton rest frame and the diproton momentum in the overall cm frame. Note that the vertical scale does not start from zero. The resolution in cosθp∗ depends upon the angle but, even in the worst case, it is no larger than the width of the bins.
Distributions in the square of the missing mass for candidates for the pp→ppX reaction with excitation energy Epp<3 MeV and θppcm⩽15.4° when the protons (a) hit different counters, and (b) the same counter. From the indicated positions of the π0 peak and the 2π0 threshold it is seen that single and double pion production can be clearly separated. Gaussian fits to the π0 peak plus a constant background yield a total number of π0 events in (a) and (b) of respectively 4425 and 1008.
Article
The pp→ppπ0 differential cross section has been measured with the ANKE spectrometer at COSY–Jülich for pion cms angles between 0° and 15.4° at a proton beam energy of 0.8 GeV. The selection of diproton pairs with an excitation energy Epp<3 MeV ensures that the final pp system is dominantly in the spin-singlet state. The kinematics are therefore very similar to those of pp→dπ+ but with different spin and isospin transitions. The cross sections are over two orders of magnitude smaller than those of pp→dπ+ and show a forward dip that is even stronger than that seen at lower energies. The results should provide a crucial extra test of pion production models in nucleon–nucleon collisions.
 
Article
We present results of the first nonperturbative calculation of η-meson production in heavy-ion collisions from 0.8 to 2 GeV/u bombarding energy. In this calculation mean-field effects as well as the dynamic population of nucleon resonances and their decay are taken into account. The results obtained are compared with very recent experiments at 1 GeV/u and are analyzed with respect to the time development of the hadronic composition of the reaction volume.
 
Left: Differential cross section for e+e−→π+π−γ, with 50°<θγ<130°. Right: bare cross section σππbare for e+e−→π+π−. Data points have statistical error attached, the gray band gives the statistical and systematic uncertainty (added in quadrature).
Left: MC signal and background distributions in the Mtrk–Mππ2 plane. Right: the same, in the Ω–Mππ2 plane. Black lines indicate the cuts described in the text.
Vertical cross section in the y–z plane of the KLOE detector, showing the small and large angle regions for photons and pions used in the different KLOE measurements.
Top left: |Fπ|2 from CMD-2 [30,31], SND [32] and the present KLOE result as function of (Mππ0)2. Bottom left: Fractional difference between CMD-2 or SND and KLOE. Top right: σππbare from BaBar [36] and the new KLOE result as function of Mππ0. Bottom right: Fractional difference between BaBar and KLOE. CMD-2, SND and BaBar data points have the total uncertainty attached. The dark (light) band in the lower plots shows statistical (total) error of the KLOE result.
Comparison of the present result, KLOE10, with the previous KLOE result, KLOE08 [7]. Left: Pion form factor |Fπ|2. Right: Fractional difference between KLOE08 and KLOE10 results. The dark (light) gray band gives the statistical (total) error for the present result. Errors on KLOE08 points contain the combined statistical and systematic uncertainty.
Article
We have measured the cross section of the radiative process e+e- -> pi+pi-gamma with the KLOE detector at the Frascati phi-factory DAPHNE, from events taken at a CM energy W=1 GeV. Initial state radiation allows us to obtain the cross section for e+e- -> pi+pi-, the pion form factor |F_pi|^2 and the dipion contribution to the muon magnetic moment anomaly, Delta a_mu^{pipi} = (478.5+-2.0_{stat}+-5.0_{syst}+-4.5_{th}) x 10^{-10} in the range 0.1 < M_{pipi}^2 < 0.85 GeV^2, where the theoretical error includes a SU(3) ChPT estimate of the uncertainty on photon radiation from the final pions. The discrepancy between the Standard Model evaluation of a_mu and the value measured by the Muon g-2 collaboration at BNL is confirmed.
 
Article
The polarization parameter for K+n charge exchange scattering has been measured at five momenta between 0.851 GeV/c and 1.351 GeV/c for centre of mass angles . Results from a phase shift analysis incorporating these results are presented. No Z∗ resonances are observed.
 
Reconstructed π 0 peak width (a) and position (b) as a function of p t in pp collisions at √ s = 7 TeV in PHOS and in the photon conversion method (PCM) compared to Monte Carlo simulations. The horizontal line in (b) indicates the nominal π 0 mass. 
a) Differential invariant cross section of π 0 production in pp collisions at √ s = 7 TeV (circles) and 0.9 TeV (squares) and of η meson production at √ s = 7 TeV (stars). The lines and the boxes represent the statistical and systematic error of the combined measurement respectively. The uncertainty on the pp cross section is not included. NLO pQCD calculations using the CTEQ6M5 PDF and the DSS (AESS for η mesons) FF for three scales µ = 0.5p t , 1p t and 2p t are shown. Dotted lines in panels b) and c) correspond to the ratios using the BKK FF. Ratio of the NLO calculations to the data parametrisations are shown in panels b), c) and d). The full boxes represent the uncertainty on the pp cross sections. 
Ratio of the two independent π 0 meson measurements to the fit of the combined normalized invariant production cross section of π 0 mesons in pp collisions at √ s = 7 TeV. 
η/π 0 ratio measured in pp collisions at √ s = 7 TeV compared to NLO pQCD predictions. 
Article
The first measurements of the invariant differential cross sections of inclusive $\pi^0$ and $\eta$ meson production at mid-rapidity in proton-proton collisions at $\sqrt{s}=0.9$ TeV and $\sqrt{s}=7$ TeV are reported. The $\pi^0$ measurement covers the ranges $0.4<p_T<7$ GeV/$c$ and $0.3<p_T<25$ GeV/$c$ for these two energies, respectively. The production of $\eta$ mesons was measured at $\sqrt{s}=7$ TeV in the range $0.4<p_T<15$ GeV/$c$. Next-to-Leading Order perturbative QCD calculations, which are consistent with the $\pi^0$ spectrum at $\sqrt{s}=0.9$ TeV, overestimate those of $\pi^0$ and $\eta$ mesons at $\sqrt{s}=7$ TeV, but agree with the measured $\eta/\pi^0$ ratio at $\sqrt{s}=7$ TeV.
 
Article
K-matrix analysis of the 00++ wave is performed in the channels ππ, , ηη and 4π in the mass region up to 1550 MeV. The fit is based on the following data: [V.V. Anisovich et al., Phys. Lett. B 323 (1994) 233; C. Amsler et al., Phys. Lett. B 333 (1994) 277; B 342 (1995) 433], πN → ππN [B. Hyams et al., Nucl. Phys. B 64 (1973) 134; A.A. Kondashov et al., Proc. 27th Intern. Conf. on High Energy Physics, Glasgow (1994) 1407; Yu.D. Prokoshkin et al., Physics-Doklady (1995), in press; D. Alde et al., Study of the f0(995) resonance in the π0π0 decay channel, Preprint CERN-PPE/94-157, 1994], [S.J. Lindenbaum and R.S. Longacre, Phys. Lett. B 274 (1992) 492; A. Etkin et al., Phys. Rev. D 25 (1982) 1786] and the inelastic cross section of the ππ interaction [M. Alston-Garnjost et al., Phys. Lett. B 36 (1971) 152]. Simultaneous analysis of these data confirms the existence of the scalar resonances: f0(980), f0(1300) and f0(1500), the poles of the amplitude being at the following complex masses (in MeV): (1008 ± 10) − i(43 ± 5), (1290 ± 25) − i(120 ± 15), and (1497 − 6) − i(61 ± 5). The fourth pole has sunk deeply into the complex plane: (1430 ± 150) − i(600 ± 100). Positions of the K-matrix poles (which are referred to the masses of bare states) are at 750 ± 120 MeV, 1240 ± 30 MeV, 1280 ± 30 MeV and 1615 ± 40 MeV. Coupling constants of the K-matrix poles to the ππ, ηη and channels are found that allow us to analyze the quark and gluonic content of bare states. It is shown that f0bare(1240) and f0bare(1615) (which are strongly related to f0(1500)) can be considered as good candidates for scalar glueball.
 
Article
We analyse hadronically quiet trilepton signatures in the T-parity conserving Littlest Higgs model and in R-parity conserving supersymmetry at the Large Hadron Collider. We identify the regions of the parameter space where such signals can reveal the presence of these new physics models above the Standard Model background and distinguish them from each other, even in a situation when the mass spectrum of the Littlest Higgs model resembles the supersymmetric pattern.
 
Article
In the context of minimal seesaw framework, we study the implications of Dirac and Majorana mass matrices in which two rigid properties coexist, namely, equalities among mass matrix elements and texture zeros. In the first part of the study, we discuss general possibilities of the Dirac and Majorana mass matrices for neutrinos with such hybrid structures. We then classify the mass matrices into realistic textures which are compatible with global neutrino oscillation data and unrealistic ones which do not comply with the data. Among the large number of general possibilities, we find that only 6 patterns are consistent with the observations at the level of the most minimal number of free parameters. These solutions have only 2 adjustable parameters, so that all the mixing angles can be described in terms of the two mass differences or pure numbers. We analyze these textures in detail and discuss their impacts for future neutrino experiments and for leptogenesis. Comment: 25 pages, 2 figures; (ver. 2) A significant revision is made for easy reading, and analyses on CP violation are added
 
Article
We show that the asymptotic symmetry algebra of geometries with Schrödinger isometry in any dimension is an infinite dimensional algebra containing one copy of Virasoro algebra. It is compatible with the fact that the corresponding geometries are dual to non-relativistic CFTs whose symmetry algebra is the Schrödinger algebra which admits an extension to an infinite dimensional symmetry algebra containing a AdS/CFT correspondence [1] has provided us with a powerful framework to study strongly coupled conformal field theories. This is done by making use of weakly coupled gravities on backgrounds containing an AdS part. According to the AdS/CFT duality there is a one to one correspondence between objects on the gravity side and those in the dual conformal field
 
Article
Considering corrections to all orders in the Planck length on the quantum state density from a generalized uncertainty principle (GUP), we calculate the statistical entropy of the scalar field on the background of the Schwarzschild black hole without any cutoff. We obtain the entropy of the massive scalar field proportional to the horizon area.
 
Article
A measurement of the cosmic ray positron fraction e+/(e++e−) in the energy range of 1–30 GeV is presented. The measurement is based on data taken by the AMS-01 experiment during its 10 day Space Shuttle flight in June 1998. A proton background suppression on the order of 106 is reached by identifying converted bremsstrahlung photons emitted from positrons.
 
Proton spectrum derived through fitting PAMELA and CREAM data. References of the proton data: AMS [44], BESS [45], ATIC2 [17], PAMELA [18] and CREAM [19]. 
Expected total fluxes of the pure electrons for the three fits corresponding to Figs. 2-4. 
1σ and 2σ parameter regions on the mχ − σv plane for the DM annihilation scenario. The lines show the 95% upper limit of Fermi γ-ray observations of the Galactic center (thin lines, with different normalization of the local density corrected, [50]) and dwarf galaxies (thick lines, [51]) for µ + µ − (black solid) and τ + τ − (blue dashed-dotted) channels respectively. 
Article
The recently reported positron fraction up to $\sim 350$ GeV by AMS-02 seems to have tension with the total electron/positron spectra detected by Fermi and HESS, for either pulsar or dark matter annihilation/decay scenario as the primary positron sources. In this work we will show that the tension will be removed by an adjustment of the primary electron spectrum. If the primary electron spectrum becomes harder above $\sim50$ GeV, similar as the cosmic ray nuclei spectrum, the AMS-02 positron fraction and Fermi/HESS data can be well fitted by both the pulsar and dark matter models. This result indicates that there should be a common origin of the cosmic ray nuclei and the primary electrons. Furthermore, this study also implies that the properties of the extra sources derived from the fitting to the AMS-02 data should depend on the form of background.
 
The “background with spectrum hardening + pulsars + dark matter annihilation into e+e−” model for the second set of electron/positron data. Top panel: the fit of the Fermi-LAT long path electron/positron total spectrum [7], the updated Fermi-LAT electron/positron total spectrum in the energy range 20–200 GeV [9], and the PAMELA electron spectrum data [28]. Bottom panel: the fit of the AMS-02 positron fraction data. The best fit parameters are presented in Table 2 (i.e., scenario (e)). The existence of dark matter particles with a rest mass ∼100 GeV and 〈σv〉χχ→e+e−∼5.5×10−27 cm3s−1 cannot be ruled out by current data.
The regions of parameter space (68.3% and 99.5% confidence levels) which provide a reasonable fit to the second set of data comparing with the bounds set by Fermi-LAT Galactic diffuse emission (adopted from [29], the short-dashed line represents the upper limits on 〈σv〉 found in the analysis with no model of the astrophysical background, while the solid line is the bound found in the analysis with a modeling of the background) and by the extra-galactic diffuse emission (adopted from [23], the long-dashed line in the bottom panel). Top panel is for the annihilation channel χχ→μ+μ− and the isothermal-sphere like dark matter distribution model is adopted. Bottom panel is for the decay channel χ→μ+μ− and the NFW dark matter distribution model is adopted. In this work we do not present the cases of annihilation/decay into τ+τ− since they have been excluded by the γ-ray observations.
The upper two panels: the “background with spectrum hardening + dark matter annihilation into μ+μ−” model for the second set of electron/positron data. The lower panels: the “background with spectrum hardening + dark matter decay into μ+μ−” model for the second set of electron/positron data. The best fit parameters are summarized in Table 2.
Article
The data collected by ATIC, CREAM and PAMELA all display remarkable cosmic-ray-nuclei spectrum hardening above the magnetic rigidity $\sim$ 240 GV. One natural speculation is that the primary electron spectrum also gets hardened (possibly at $\sim 80$ GV) and the hardening partly accounts for the electron/positron total spectrum excess discovered by ATIC, HESS and Fermi-LAT. If it is the case, the increasing behavior of the subsequent positron-to-electron ratio will get flattened and the spectrum hardening should be taken into account in the joint fit of the electron/psoitron data otherwise the inferred parameters will be biased. Our joint fits to the latest AMS-02 positron fraction data together with the PAMELA/Fermi-LAT electron/positron spectrum data suggest that the primary electron spectrum hardening is needed in most though not all modelings. The bounds on dark matter models have also been investigated. In the presence of spectrum hardening of primary electrons, the amount of dark-matter-originated electron/positron pairs needed in the modeling is smaller. Even with such a modification, the annihilation channel $\chi\chi \rightarrow \mu^{+}\mu^{-}$ has been tightly constrained by the Fermi-LAT Galactic diffuse emission data. The decay channel $\chi\rightarrow \mu^{+}\mu^{-}$ is found to be viable.
 
Iso-m DM contours in Scenario I, with r L = r Q = 0 and μ L = μ Q (left), and Scenario II, with μ L = r Q = 0 (right), that give Ω DM h 2 = 0.11. The green shaded regions are allowed at the 95% C.L. by resonance searches at the LHC, and the blue shaded regions are compatible with antiproton data.
Iso-mDM contours in Scenario I, with rL=rQ=0 and μL≠μQ (left), and Scenario II, with μL=rQ=0 (right), that give ΩDMh2=0.11. The green shaded regions are allowed at the 95% C.L. by resonance searches at the LHC, and the blue shaded regions are compatible with antiproton data.
Left: Fits to AMS-02 e− and e+ spectra for different leptonic branching fractions, for a 1 TeV KK photon. Variations in the galactic e± background and boost factor are marginalized over for each point. Middle: 3σ bounds on BRH/BRL from the AMS-02 e± spectra and the PAMELA antiproton spectrum. Right: The shaded region shows the p¯ signal + background spectra for mDM=1 TeV that correspond to the 3σ fit to AMS-02. The DM-only contributions (black dashed) are higher than the PAMELA data, even without considering the galactic background. The separation between the polynomial fit to the p¯ data (gray dotted) and an extreme possibility for the background (labeled “Bkg”) gives an idea of the size of the deviation permitted by our modeling of the background uncertainty.
e± (solid) and antiproton (dotted) injection spectra from leptonic (blue) and hadronic (red) annihilation channels, with BRL=0.4 and BRH=0.6. The end-point peak is due to DM annihilation into e+e−. The DM mass is 1 TeV.
Article
The anomaly detected by AMS-02 and PAMELA in the cosmic-ray positron flux when interpreted as arising from dark matter annihilation suggests that dark matter may interact differently with hadrons and leptons so as to remain compatible with cosmic-ray antiproton data. Such a scenario is readily accommodated in models with extra spatial dimensions. We study indirect detection of Kaluza-Klein (KK) dark matter in Universal Extra Dimensions with brane-localized terms and fermion bulk masses: Next-to-Minimal Universal Extra Dimensions. So that an excess of antiprotons is not produced in explaining the positron anomaly, it is necessary that the KK bulk masses in the lepton and hadron sectors be distinct. Even so, we find that cosmic-ray data disfavor a heavy KK photon dark matter scenario. Also, we find these scenarios with flavor-universal bulk masses to be in conflict with dijet and dilepton searches at the LHC.
 
Article
The excitation of the 02+ (7.65 MeV) state in 12C by inelastic alpha scattering is investigated using microscopic resonating group wave functions in a coupled channel folding model. The importance of coupling to other states and the influence of varying the optical potential in the excited states is studied. Both effects must be taken into account for a quantitative description.
 
Upper three panels: Contour lines of 68th, 95th, and 99th percentile of the likelihood function (the chi-squared distribution) for the wino decays through the interactions L1L2Eic (top-left panel), L3L1Eic (top-right panel), and L3L2Eic (middle-left panel), where i=1,2, and 3. See text for gray and yellow shaded regions. Lower three panels: The positron fraction (middle-right panel), the electron flux (bottom-left panel), and the positron flux (bottom-right panel) with the latest AMS-02 data for the decay through the interaction L3L1E2c. See text for red solid lines and red shaded regions. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Article
We revisit the decaying wino dark matter scenario in the light of the updated positron fraction, electron and positron fluxes in cosmic ray recently reported by the AMS-02 collaboration. We show the AMS-02 results favor the mass of the wino dark matter at around a few TeV, which is consistent with the prediction on the wino mass in the pure gravity mediation model.
 
Energy spectra of antiproton produced by non-relativistic annihilation of DM. Red and blue lines correspond to those for χχ → W + W − and ¯ bb, respectively. The DM mass is taken to be 2 TeV. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) In Fig. 1, we also show the antiproton spectrum from χχ → b ¯ b.
Fitting parameters for decaying DM.
The antiproton to proton ratio in the Wino DM scenario for MIN (top), MED (middle) and MAX (bottom) propagation models. Red lines are those for the Wino mass of 2.9 TeV, while blue lines are those for the Wino mass of 2.2 TeV (MIN), 1.7 TeV (MED), and 1.2 TeV (MAX). The solid lines are signal plus background, while the dashed lines are signal-only. The background is shown in the green line, and the AMS-02 data are shown by the cyan points. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
The antiproton to proton ratio for MIN (top), MED (middle) and MAX (bottom) propagation models. The red lines are those predicted by the DM annihilation (left) and decay (right). For the annihilation case, the DM mass is taken to be 0.5 (solid), 2 (dotted), 10 (dashed), and 20 TeV (long-dashed), while the annihilation cross section is taken to be 2×10−23, 2×10−24, and 6×10−25cm3/s, for MIN, MED, and MAX propagation models, respectively. For the decay case, the DM mass is taken to be 1 (solid), 3 (dotted), 10 (dashed), and 30 TeV (long-dashed), while the lifetime is 1×1026, 5×1026, and 2×1027 s, for MIN, MED, and MAX propagation models, respectively. The background is shown in the green line, and the AMS-02 data are shown by the cyan points. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Energy spectra of antiproton produced by non-relativistic annihilation of DM. Red and blue lines correspond to those for χχ→W+W− and b¯b, respectively. The DM mass is taken to be 2 TeV. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Article
Recently the AMS-02 experiment reported an excess of cosmic ray antiprotons over the expected astrophysical background. We interpret the excess as a signal from annihilating or decaying dark matter and find that the observed spectrum is well fitted by adding contributions from the annihilation or decay of dark matter with mass of O(TeV) or larger. Interestingly, Wino dark matter with mass of around 3 TeV, whose thermal relic abundance is consistent with present dark matter abundance, can explain the antiproton excess. We also discuss the implications for the decaying gravitino dark matter with R-parity violation.
 
Thermally averaged dark matter annihilation cross section at the current Universe as a function of ϵ in the lower horizontal axis, as required by the observed relic density. The upper horizontal axis gives the corresponding value of λ4.
Spectra of the positron flux (left) and the ratio of antiproton-to-proton fluxes (right) in comparison with those observed by AMS-02 from cosmic rays, drawn in thick curves. Red solid curves are used for MIN, dashed green curves for MED, and dash-dotted blue curves for MAX. Also indicated are the values of ϵ in the left plot and vΔ in the right plot. The background in the left plot is given by the purple dotted curve, and those in the right plot are given by the thin curves.
Article
We propose a dark matter explanation to simultaneously account for the excess of antiproton-to-proton and positron power spectra observed in the AMS-02 experiment while having the right dark matter relic abundance and satisfying the current direct search bounds. We extend the Higgs triplet model with a hidden gauge symmetry of $SU(2)_X$ that is broken to $Z_3$ by a quadruplet scalar field, rendering the associated gauge bosons stable weakly-interacting massive particle dark matter candidates. By coupling the complex Higgs triplet and the $SU(2)_X$ quadruplet, the dark matter candidates can annihilate into triplet Higgs bosons each of which in turn decays into lepton or gauge boson final states. Such a mechanism gives rise to correct excess of positrons and antiprotons with an appropriate choice of the triplet vacuum expectation value. Besides, the model provides a link between neutrino mass and dark matter phenomenology.
 
Article
A recently proposed holographic duality allows the Bekenstein–Hawking entropy of extremal rotating black holes to be calculated microscopically, by applying the Cardy formula to the two-dimensional chiral CFTs associated with certain reparameterisations of azimuthal angular coordinates in the solutions. The central charges are proportional to the angular momenta of the black hole, and so the method degenerates in the case of static (non-rotating) black holes. We show that the method can be extended to encompass such charged static extremal AdS black holes by using consistent Kaluza–Klein sphere reduction ansatze to lift them to exact solutions in the low-energy limits of string theory or M-theory, where the electric charges become reinterpreted as angular momenta associated with internal rotations in the reduction sphere. We illustrate the procedure for the examples of extremal charged static AdS black holes in four, five, six and seven dimensions.
 
Top-cited authors
Ren-Yuan Zhu
  • California Institute of Technology
Martin Grunewald
  • University College Dublin
Rudolf Frühwirth
  • Austrian Academy of Sciences (OeAW)
Christophorus Grab
Dongchul Son
  • Kyungpook National University