Ann E. Nelson

University of Washington | UW · Department of Physics

Exotic new particles carrying baryon number and with mass of order the nucleon mass have been proposed for various reasons including baryogenesis, dark matter, mirror worlds, and the neutron lifetime puzzle. We show that the existence of neutron stars with mass greater than 0.7 $M_\odot$ places severe constraints on such particles, requiring them t...

We propose a model for CP violating oscillations of neutral, heavy-flavored baryons into antibaryons at rates which are within a few orders of magnitude of their lifetimes. The flavor structure of the baryon violation suppresses neutron oscillations and baryon number violating nuclear decays to experimentally allowed rates. We also propose a scenar...

Neutrino masses and the number of light neutrino species can be tested in a variety of laboratory experiments and also can be constrained by particle astrophysics and precision cosmology. A conflict between these various results could be an indication of new physics in the neutrino sector. In this paper we explore the possibility for reconciliation...

We analyze neutron-antineutron oscillation in detail, developing a Hamiltonian describing the system in the presence of electromagnetic fields. While magnetic fields can couple states of different spin, we show that, because of Fermi statistics, this coupling of different spin states does not involve baryon-number--changing transitions and, therefo...

We propose a new mechanism for baryogenesis at the 1-200 MeV scale. Enhancement of CP violation takes place via interference between oscillations and decays of mesinos--bound states of a scalar quark and antiquark and their CP conjugates. We present the mechanism in a simplified model with four new fundamental particles, with masses between 300 GeV...

We propose the framework generalized supersoft supersymmetry breaking. "Supersoft" models, with D-type supersymmetry breaking and heavy Dirac gauginos, are considerably less constrained by the LHC searches than the well studied MSSM. These models also ameliorate the supersymmetric flavor and CP problems. However, previously considered mechanisms fo...

We propose the framework, "generalized supersoft supersymmetry breaking." "Supersoft" models, with D-type supersymmetry breaking and heavy Dirac gauginos, are considerably less constrained by the LHC searches than the well studied MSSM. These models also ameliorate the supersymmetric flavor and CP problems. However, previously considered mechanisms...

Cold dark matter explains a wide range of data on cosmological scales. However, there has been a steady accumulation of evidence for discrepancies between simulations and observations at scales smaller than galaxy clusters. Solutions to these small scale structure problems may indicate that simulations need to improve how they include feedback from...

We consider some contributions to rare processes in $B$ meson decays from a Dark Sector containing 2 light unstable scalars, with large couplings to each other and small mixings with Standard Model Higgs scalars. We show that existing constraints allow for an exotic contribution to high multiplicity final states with a branching fraction as large a...

We study how many-body effects alter the dark matter (DM) thermalization time inside neutron stars. We find that Pauli blocking, kinematic constraints, and superfluidity and superconductivity in the neutron star significantly affect the DM thermalization time, in general lengthening it. This changes the DM mass and DM-nucleon cross section constrai...

The existence of light sterile neutrinos in the eV mass range with relatively large mixing angles with the active neutrinos has been proposed for a variety of reasons, including to improve the fit to the LSND and MiniBooNE neutrino oscillation experiments, and reactor disappearance experiments. In ref. Phys. Rev. D 84, 053001 (2011), it was shown t...

We describe a model of quarks which identifies the large global symmetries of little Higgs models with the global flavor symmetries that arise in a deconstruction of the extra-dimensional 'topological insulator' model of flavor. The nonlinearly realized symmetries of little Higgs theories play a critical role in determining the flavor structure of...

We explore the possibility that the dark matter is a condensate of a very light vector boson. Such a condensate could be produced during inflation, provided the vector mass arises via the Steuckelberg mechanism. We derive bounds on the kinetic mixing of the dark matter boson with the photon, and point out several potential signatures of this model.

We present a simple, perturbative, and renormalizable model with a flavor symmetry which can explain both the t-tbar forward-backward asymmetry and the bump feature present in the dijet mass distribution of the W+jj sample in the range 120-160 GeV that was recently reported by the CDF collaboration. The flavor symmetry not only ensures the flavor/C...

Recent evidence for a CP violating asymmetry in the semileptonic decays of Bs mesons cannot be accommodated within the standard model. Such an asymmetry can be explained by new physics contributions to ΔB=2 components of either the mass matrix or the decay matrix. We show that mixing with a hidden pseudoscalar meson with a mass around 5 GeV can res...

Neutrinos may mix with ultralight fermions, which gives flavor oscillations, and with heavier fermions, which yields short distance flavor change. I consider the case where both effects are present. I show that in the limit where a single oscillation length is experimentally accessible, the effects of heavier fermions on neutrino oscillations can g...

We consider the cosmology of a model in which the dark matter is part of a nonminimal hidden sector which is not in thermal equilibrium with the standard model particles at the time of dark matter decoupling. We show that the annihilation rate of dark matter can be either lower or higher than in standard thermal decoupling models, but no higher tha...

We consider searching for light sterile fermions and new forces by using long baseline oscillations of neutrinos and antineutrinos. A new light sterile state and/or a new force can lead to apparent CPT violation in muon neutrino and antineutrino oscillations. As an example, we present an economical model of neutrino masses containing a sterile neut...

We construct a model of an unparticle sector consisting of a supersymmetric SU(N) gauge theory with the number of flavors in the Seiberg conformal window. We couple this sector to the MSSM via heavy messengers. The resulting low energy theory has a Higgs coupling to unparticles. The Higgs vev drives the hidden Seiberg sector to a new conformal fixe...

We present a simple model in which dark matter couples to the standard model through a light scalar intermediary that is itself unstable. We find this model has several notable features, and allows a natural explanation for a surplus of positrons, but no surplus of anti-protons, as has been suggested by early data from PAMELA and ATIC. Moreover, th...

In theories of axion dark matter with large axion decay constant, temperature variations in the CMB are extremely sensitive to perturbations in the initial axion field, allowing one to place a lower bound on the total amount of inflation. The most stringent bound comes from axion strings, which for axion decay constant f=10^17 GeV would currently b...

10 pages.-- PACS number: 12.60.Cn.-- Published in: Phys. Rev. D 77, 095006 (2008) (10 pages).-- Final full-text version of the paper available at: http://dx.doi.org/10.1103/PhysRevD.77.095006. We show that for a force mediated by a vector particle coupled to a conserved U(1) charge, the apparent range and strength can depend on the size and density...

We consider a model of neutrino oscillations with three additional sterile neutrinos and a gauged B-L interaction. We find allowed values of the model parameters which can reconcile the results of the evidence for antimuon neutrino to antielectron neutrino conversion seen at the LSND neutrino oscillation experiment with the null results of the Mini...

We show that inclusion of an extremely small quartic coupling constant in the potential for a nearly massless scalar field greatly increases the experimentally allowed region for the mass term and the coupling of the field to matter. Comment: 17 pages, 1 figure,refs added, equation typos corrected, conclusions unchanged

We present a supersymmetric model of dark energy from Mass Varying Neutrinos which is stable against radiative corrections to masses and couplings, and free of dynamical instabilities. This is the only such model of dark energy involving fields with significant couplings to any standard model particle. We briefly discuss consequences for neutrino o...

Two paradigms for the origin of electroweak superconductivity are a weakly coupled scalar condensate, and a strongly coupled fermion condensate. The former suffers from a finetuning problem unless there are cancelations to radiative corrections, while the latter presents potential discrepancies with precision electroweak physics. Here we present a...

We consider a class of theories in which neutrino masses depend significantly on environment, as a result of interactions with the dark sector. Such theories of mass varying neutrinos were recently introduced to explain the origin of the cosmological dark energy density and why its magnitude is apparently coincidental with that of neutrino mass spl...

We describe a natural UV complete theory with a composite little Higgs. Below a TeV we have the minimal Standard Model with a light Higgs, and an extra neutral scalar. At the TeV scale there are additional scalars, gauge bosons, and vector-like charge 2/3 quarks, whose couplings to the Higgs greatly reduce the UV sensitivity of the Higgs potential....

Abstract We review recent experimental tests of the gravitational inverse-square law and the wide variety of theoretical considerations that suggest the law may break down in experimentally accessible regions.

We show that mass varying neutrinos (MaVaNs) can behave as a negative pressure fluid which could be the origin of the cosmic acceleration. We derive a model independent relation between the neutrino mass and the equation of state parameter of the neutrino dark energy, which is applicable for general theories of mass varying particles. The neutrino...

We review recent experimental tests of the gravitational inverse-square law and the wide variety of theoretical considerations that suggest the law may break down in experimentally accessible regions.

I describe, from the bottom up, a sequence of natural effective field theories. Below a TeV we have the minimal standard model with a light Higgs, and an extra neutral scalar. In the 1-10 TeV region these scalars are part of a multiplet of pseudo Nambu-Goldstone Bosons. Interactions with additional TeV mass scalars, gauge bosons, and vector-like ch...

We propose a supersymmetric extension of the standard model which does not have a ``mu'' supersymmetric Higgs mass parameter. The matter content of the MSSM is extended with three additional chiral superfields: one singlet, an SU(2) triplet and a color octet, and an approximate U(1)_R symmetry naturally guarantees that tan(beta) is large, explainin...

In the MSSM, an unfortunate prediction of minimal anomaly mediated supersymmetry breaking is that the slepton masses squared are negative. This problem is particularly intractable because of the insensitivity of anomaly mediation to ultraviolet physics. In this paper we note that tree level couplings to the conformal compensator in the Kahler poten...

Theories in which supersymmetry is broken on another brane, which is separated from the minimal supersymmetry standard model (MSSM) matter fields in an extra dimension, are attractive because they may solve the supersymmetric flavor problem. We consider the effects in such theories of new messenger fields with standard model gauge charges and with...

We introduce a new supersymmetric extension of the standard model in which the gauge sector contains complete N=2 supersymmetry multiplets. Supersymmetry breaking from the D-term vev of a hidden sector U(1) gauge field leads to Dirac soft supersymmetry breaking gaugino masses, and a new type of soft scalar trilinear couplings. The resulting squark...

We propose a supersymmetric extension of the standard model which is a realistic alternative to the MSSM, and which has several advantages. No ``mu'' supersymmetric Higgs/Higgsino mass parameter is needed for sufficiently heavy charginos. An approximate U(1) R symmetry naturally guarantees that tan beta is large, explaining the top/bottom quark mas...

Recently a new class of theories of electroweak symmetry breaking have been constructed. These models, based on deconstruction and the physics of theory space, provide the first alternative to weak-scale supersymmetry with naturally light Higgs fields and perturbative new physics at the TeV scale. The Higgs is light because it is a pseudo-Goldstone...

We present an economical theory of natural electroweak symmetry breaking, generalizing an approach based on deconstruction. This theory is the smallest extension of the Standard Model to date that stabilizes the electroweak scale with a naturally light Higgs and weakly coupled new physics at TeV energies. The Higgs is one of a set of pseudo Goldsto...

In theories in which SUSY is broken on a brane separated from the MSSM matter fields, supersymmetry breaking is naturally mediated in a variety of ways. Absent other light fields in the theory, gravity will mediate supersymmetry breaking through the conformal anomaly. If gauge fields propagate in the extra dimension they, too, can mediate supersymm...

Models with extra dimensions have changed our understanding of the hierarchy problem. In general, these models explain the weakness of gravity by diluting gravity in a large bulk volume, or by localizing the graviton away from the standard model. In this paper, we show that the warped geometries necessary for the latter scenario can naturally induc...

Recently, interesting 4-D Lorentz violating models have been proposed, in which all particles have a common maximum velocity $c$, but gravity propagates (in the preferred frame) with a different maximum velocity $c_g \neq c$. We show that the case $c_g < c$ is very tightly constrained by the observation of the highest energy cosmic rays. Assuming a...

We explore the effects of a strongly-coupled, approximately scale-invariant sector on the renormalization of soft supersymmetry breaking terms. A useful formalism for deriving exact results for renormalization of soft supersymmetry breaking terms is given in an appendix, and used to generalize previously known results to include the effects of nont...

We present a new mechanism, which does not require any flavor symmetry, to explain the small Yukawa couplings and CKM mixing angles. The Yukawa matrices are assumed to be random at short distances and the hierarchical structure is generated in the infrared by renormalization group flow. The generic qualitative predictions of this mechanism are in g...

We construct a class of solutions to the Einstein's equations for dimensions greater than or equal to six. These solutions are characterized by a non-trivial warp factor and possess a non-compact extra dimension. We study in detail a simple model in six dimensions containing two four branes. One of each brane's four spatial directions is compactifi...

We consider supersymmetric theories where the standard-model quark and lepton fields are localized on a "3-brane" in extra dimensions, while the gauge and Higgs fields propagate in the bulk. If supersymmetry is broken on another 3-brane, supersymmetry breaking is communicated to gauge and Higgs fields by direct higher-dimension interactions, and to...

A massless up quark is an intriguing possible solution to the strong CP problem. We discuss how lattice computations can be used in conjunction with chiral perturbation theory to address the consistency of mu = 0 with the observed hadron spectrum and interactions. It is not necessary to simulate very light quarks - three flavor partially quenched c...

A massless up quark is an intriguing possible solution to the strong CP problem. We discuss how lattice computations can be used in conjunction with chiral perturbation theory to address the consistency of m(u) = 0 with the observed hadron spectrum and interactions. It is not necessary to simulate very light quarks - three flavor partially quenched...

I construct solutions to Einstein's equations in 6 dimensions with bulk cosmological constant and intersecting 4-branes. Solutions exist for a continuous range of 4-brane tension, with long distance gravity localized to a 3+1 dimensional Minkowski intersection, provided that the additional tension of the intersection satisfies one condition. Commen...

Bekenstein has proposed the bound S{le}{pi}M{sup 2}{sub P}L{sup 2} on the total entropy S in a volume L{sup 3} . This nonextensive scaling suggests that quantum field theory breaks down in large volume. To reconcile this breakdown with the success of local quantum field theory in describing observed particle phenomenology, we propose a relationship...

Recently, a number of authors have challenged the conventional assumption that the string scale, Planck mass, and unification scale are roughly comparable. It has been suggested that the string scale could be as low as a TeV. In this note, we explore constraints on these scenarios. We argue that the most plausible cases have a fundamental scale of...

We discuss general predictions for neutrino masses and mixing angles from R parity violation in the Minimal Supersymmetric Standard Model. If the soft supersymmetry breaking terms are flavor blind at short distance, then the leptonic analogue of the CKM matrix depends on only two real parameters, which are completely determined by fits to solar and...

We extend the "naive dimensional analysis" arguments used in QCD for estimating the strengths of operators in chiral Lagrangians to strongly coupled supersymmetric theories. In particular, we show how to count factors of 4ß---an inexact science, but nevertheless a useful art when such theories are used to model real particle physics. 1 Introduction...

We present a supersymmetric model of flavor. A single U(1) gauge group is responsible for both generating the flavor spectrum and communicating supersymmetry breaking to the visible sector. The problem of Flavor Changing Neutral Currents is overcome, in part using an `Effective Supersymmetry' spectrum among the squarks, with the first two generatio...

this paper we will assume that the supersymmetry breaking terms have CP-violating phases and see whether these phases can account for sufficient baryogenesis without violating the electric dipole moment bounds. In the MSSM, the requirement of a sufficiently first order phase transition places upper limits on the Higgs and stop (supersymmetric partn...

We discuss the phenomenology of a class of supersymmetric models in which some of the quark and lepton superfields are an integral part of a dynamical supersymmetry breaking sector. The corresponding squarks and sleptons are much heavier than any other superpartners, and could naturally have masses as high as ∼ 40 TeV. We discuss a general set of c...

We extend the “naïve dimensional analysis” arguments used in QCD for estimating the strengths of operators in chiral Lagrangians to strongly coupled supersymmetric theories. In particular, we show how to count factors of 4π — an inexact science, but nevertheless a useful art when such theories are used to model real particle physics.

I review the motivation for dynamical supersymmetry breaking, the various mechanisms which have been discovered, and the prospects for model building. Comment: 5 pages. invited talk given at SUSY97, May27-31, 1997, University of Pennsylvania

The most severe constraints on quark-lepton four-fermion contact interactions come from the agreement of atomic parity violation measurements with the standard model. In this Letter, I note that, for contact interactions which arise in theories of composite quarks and leptons, approximate global symmetries other than parity can eliminate the contri...

We discuss how to extract non-standard-model effects from B-factory phenomenology. We then analyze the prospects for uncovering evidence for effective supersymmetry, a class of supersymmetric models which naturally suppress flavor changing neutral currents and electric dipole moments without squark universality or small CP violating phases, in expe...

We construct explicit examples with a horizontal, ``anomalous'' $U(1)$ gauge group, which, in a supersymmetric extension of the standard model, reproduce qualitative features of the fermion spectrum and CKM matrix, and suppress FCNC and proton decay rates without the imposition of global symmetries. We review the motivation for such ``more'' minima...

We should be taking advantage of recent gains in our nonperturbative understanding of supersymmetric gauge theories to find the “standard” model of of dynamical supersymmetry breaking, and possibly of flavor as well. As an illustration of the possibilities for understanding the flavor hierarchy, I describe a realistic, renormalizable, supersymmetri...

Effective Supersymmetry is presented as a theory of physics above the electroweak scale which has significant theoretical advantages over both the standard model and the Minimal Supersymmetric Standard Model (MSSM). The theory is supersymmetric at short distances but differs significantly from the MSSM. Flavor symmetry violation is intimately relat...

We describe a realistic, renormalizable, supersymmetric ``quindecuplet'' model in which the top quark, left handed bottom quark, and up-type Higgs boson are composite, with a compositeness scale $\sim 1-3$ TeV. The top-Higgs Yukawa coupling is a dynamically generated strong interaction effect, and is naturally much larger than any other Yukawa coup...

We propose a simple and natural model of dynamical supersymmetry breaking, which could be used as a mechanism for spontaneous supersymmetry breaking in a gravitationally coupled hidden sector. The gaugino masses in the visible sector are naturally of the same size as the squark, slepton, and gravitino masses.

We report the construction of large new classes of models which break supersymmetry dynamically. We then turn to model building. Two of the principal obstacles to constructing simple models of dynamical supersymmetry breaking are the appearance of Fayet-Iliopoulos D terms and difficulties in generating a $\mu$ term for the Higgs fields. Among the n...

We develop a new and general method to calculate the effects of CP violation from extensions of the standard model on the mechanism of electroweak baryogenesis. We illustrate its applicability in the framework of two-higgs doublet models.

Relatively simple models can be constructed in which supersymmetry is dynamically broken at energies of $10^5-10^7$ GeV. Models of this kind do not suffer from the naturalness and cosmological difficulties of conventional supergravity models, and make definite predictions for the spectrum of supersymmetric particle masses. Thus ``Renormalizable Vis...

We present a model in which supersymmetry is dynamically broken at comparatively low energies. Previous efforts to construct simple models of this sort have been hampered by the presence of axions. The present model, which exploits an observation of Bagger, Poppitz, and Randall to avoid this problem, is far simpler than previous constructions. Mode...

We include the effects of diffusion in the electroweak spontaneous baryogenesis scenario and show that it can greatly enhance the resultant baryon density, by as much as a factor of 1/αw4 ∼ 106 over previous estimates. Furthermore, the baryon density produced is rather insensitive to parameters characterizing the first order weak phase transition,...

We point out a connection between R symmetry and \susy\ breaking. We show that the existence of an R symmetry is a necessary condition for \susy\ breaking and a spontaneously broken R symmetry is a sufficient condition provided two conditions are satisfied. These conditions are: {\it genericity}, \ie\ the effective Lagrangian is a generic Lagrangia...

We provide a taxonomy of dynamical supersymmetry breaking theories, and discuss the cosmological implications of the various types of models. Models in which supersymmetry breaking is produced by chiral superfields which only have interactions of gravitational strength (\eg\ string theory moduli) are inconsistent with standard big bang nucleosynthe...

We show that if there are only two Higgs doublets in the supersymmetric standard model, large tan β requires a fine tuning in the parameters of the Lagrangian of order (1/tan β), which cannot be explained by any approximate symmetry. With an extended Higgs sector, large tan β can be natural. We give an explicit example with four doublets in which i...

Conventional approaches to supersymmetric model building suffer from several naturalness problems: they do not explain the large hierarchy between the weak scale and the Planck mass, and they require fine tuning to avoid large flavor changing neutral currents and particle electric dipole moments. The existence of models with dynamical supersymmetry...

Recent work on generating the excess of matter over antimatter in the early universe during the electroweak phase transition is reviewed. Comment: 50 pages (figures on request), uses harvmac (table of contents correct for "l" format), UCSD-93-2,BU-HEP-93-4

Requiring that the baryon number of the universe be generated by anomalous electroweak interactions places strong constraints on the minimal supersymmetric standard model. In particular, the electric dipole moment of the neutron must be greater than 10−27e cm. Improvement of the current experimental bound on the neutron's electric dipole moment by...

We examine a recent claim that Debye screening will affect the charge transport mechanism of anomalous electroweak baryogenesis. We show that the effects of gauge charge screening do not affect the baryon number produced during a first order electroweak phase transition. (Requires harvmac.tex) Comment: 12 pages, UCSD-PTH-92-19, BU-HEP-92-20

Conventional solutions to the strong CP problem all require the existence of global symmetries. However, quantum gravity may destroy global symmetries, making it hard to understand why the electric dipole moment of the neutron (EDMN) is so small. We suggest here that CP is actually a discrete gauge symmetry, and is therefore not violated by quantum...

We show how the baryon number of the universe may be created by anomalous weak interactions during a first-order weak phase transition, in both conventional two-Higgs doublet models and in the supersymmetric standard model. The process we analyze involves non-equilibrium charge transport during the phase transition. Given current estimates of anoma...

We discuss baryogenesis during the weak phase transition in models with CP violation in the scalar potential. If the transition is first order, classical evolution of the scalar fields can split particle-antiparticle energy levels. A net baryon number will then be produced by anomalous weak baryon number violation. We can explain the observed value...

A model with three Majorana neutrinos of mass ∼0, 17 keV and 200–250 keV is described, which is cosmologically safe and naturally consistent with the absence of observed neutrinoless double beta decay and neutrino oscillations.

Testable relations among the neutrino masses and mixing angles have been found which are valid if there are only three Majorana neutrinos, and if a 17-keV neutrino appears in beta decays with a 1 percent probability. There are not allowed possibilities. Either the 17-keV neutrino is essentially a Dirac neutrino made of the muon antineutrino and a l...

I examine a simple model of spontaneous family SO(3) and CP violation in which the neutron naturally has a small but measurable electric dipole moment. In addition the model constraints several quark mixing angles and the top quark mass. At tree level the top quark mass satisfies mt⩽mbmcKub/mdKcb, where K is the Kobayashi-Maskawa (KM) matrix and mi...

We examine the consequences of a model for baryogenesis during the weak phase transition. We assume that baryon number violation comes from anomalous weak interactions and that the necessary CP violation comes from neutrino masses. We find that a baryon to entropy ratio of 10−10 can be produced if the weak phase transition is first order, the tau n...

I consider a model where an effective current mass for the up quark is provided by the interactions of a new neutral light colored scalar and a charge colorless fermion. The model has no strong CP problem. A new confining U (1) prevents the occurence of physical states with fractional charges. There are new light (a few GeV) states which rapidly de...

Using the non-linear SU(3)L × SU(3)R chiral lagrangian coupled to a field theory of nuclear forces, we show that a bound state of baryons with a well-defined surface may conceivably form in the presence of kaon condensation. This state is of similar density to ordinary nuclei, but has net strangeness equal to about two thirds the baryon number. We...

I discuss a model where the strong CP problem is solved by introducing a Peccei-Quinn symmetry, but there is no axion. The model is similar to some variant axion models, however the Peccei-Quinn symmetry is spontaneously broken only by the QCD-induced quark condensate, not by weak-scale physics. There are both an extra light fundamental scalar and...

We discuss a simple model for baryogenesis during the weak phase transition, which uses the anomalous baryon violation in the weak interactions. A departure from thermal equilibrium is provided if the transition is first order, and CP violation occurs in the neutrino couplings. Generating a sufficiently large baryon number requires that the τ neutr...

We examine the constraints on baryogenesis if anomalous weak baryon violation is in thermal equilibrium at high temperatures. If neutrinos have Majorana masses, there is an upper bound on the scale of baryogenesis: T0≲1012 GeV(1 eV/mν)2, where mν is the mass of the lightest neutrino, and no baryon number is generated at temperatures below T0.

It is possible that another QCD phase transition took place in the early universe after the confining and chiral symmetry breaking transition. The second transition is from a kaon condensate phase to the ordinary phase. Remnants of this phase transition may include effects on nucleosynthesis and nuggets of strange baryon matter.

We consider several processes which are sensitive to the existence of a light gauge boson coupled to baryon number. In the mass region between 10 Mev and Mπ≈140 MeV the best limits on the coupling come from rare π0 decays, while a boson with mass between Mπ and 2Mπ may be observed in K+ decays, or η decays. Heavier gauge bosons will decay hadronica...

There is some evidence for non-zero strange matrix elements in the proton, if one combines experimental results and SU(3) symmetry. In the quark model, the hyperon masses depend nonlinearly on the strange quark current mass ms, and so the standard calculation of 〈p∥s̄s∥p〉 is untrustworthy. The s̄s matrix element can be calculated in the chiral quar...

We show that one may expect a charged kaon condensate to form in matter at several times nuclear density. The condensate is driven to a large extent by the “sigma term Interaction” between mesons and baryons — a symmetry breaking effect proportional to the strange quark mass. Using the SU(3) × SU(3) chiral Lagrangian to model meson-baryon interacti...

We discuss kaon condensation in heavy ion collisions as a way of probing the strangeness content of the proton. Possible signals include an excess of strange particles, long lived exotic states, and jets of K+s or K0's. Junior Fellow, Harvard Society of Fellows. Research supported In part by the National Science Foundation under Grant Number PHY-82...

We show that a new phase of matter may form in heavy ion collisions at baryon densities above three to four times nuclear density. This phase is characterized by a Bose-Einstein condensate of kaons or etas; or equivalently, a realignment of the q condensate in flavor space. Possible signals from this transition include an excess of hyperons, cohere...

It has been suggested that charged pions form a Bose-Einstein condensate in baryonic matter at zero temperature and about twice nuclear density. In this letter it is shown that at somewhat higher densities one finds a charged kaon condensate, driven to a large extent by the “stgma term” interaction with baryons. Using the SU(3) × SU(3) chiral lagra...

A problem is pointed out in a class of models of composite fermions and a composite Higgs. These theories seem to automatically contain a Peccei-Quinn symmetry; a U(1) symmetry which is exact up to a color anomaly. Such a symmetry is acceptable only if it results in an invisible axion. In one attempt at a realistic model SU(2)w must be embedded in...

A model is discussed in which e + τ-μ emerges as an approximate, but very good, accidental symmetry of the lepton mass matrices. Consequently a heavy neutrino can be accommodated without conflicts with νμ oscillation or neutrinoless double β decay data. The model has a Goldstone boson which may be interpreted as the axion, the majoron, or a familon...

We discuss constraints on the three by three Majorana neutrino mass matrix consistent with neutrinoless double ..beta.. decay experiments, neutrino oscillation experiments, and the existence of a 17-keV neutrino. We find that ..nu../sub ..mu../ and ..nu../sub tau/ must be nearly degenerate, or ..nu../sub ..mu../ must be heavier than 250 keV. A new...

We propose that the UA1 monojet events are due to the decay of a colored gauge boson, of mass 160–180 GeV, decaying into Z+jet. The decay of this boson into W+jets could explain the anomalous events seen by UA2.