122685473
Ladder approximation, scalar-exchange mesons, and Bethe--Salpeter scattering states
120766753
Stability of the electron in the SU(5) and GWS models
Within the framework of the SU(5) model and by using non-zero vacuum expectation values for both charged and neutral Higgs fields, the lifetime of the electron ( tau e) can be expressed in terms of the photon mass (mgamma ). Using the upper limit of 10-24 GeV for mgamma given by studies of Jupiter's magnetic field, a lower limit of 1027 years is obtained for tau e, while the upper limit of 10-36 GeV for mgamma given by studies of galactic magnetic fields yielded a lower limit of 1051 years for tau e. The values for tau e can be obtained without giving rise to light Higgs particles. In contrast, the standard GWS model with two Higgs doublets gave rise to comparable values for tau e, but yielded a light Higgs particle with masses similar to mgamma .
121710663
SPIN-2 GLUON - GRAVITON MODEL WITH BARYON NUMBER NONCONSERVATION
We have shown how a weak-strong gravity model with Higgs fields can contain a baryon-number-violating mechanism. If more than one set of Higgs particles are allowed, the Higgs-fermion coupling will generate the violation of baryon-number symmetry spontaneously. To illustrate our point, we present some numerical examples on quark and nucleon decay. We find that some of the quarks can decay into leptons, antileptons, and pions with very short lifetimes. The proton is found to be much more stable than the neutron and both have possible baryon-number-violating modes of decay with very long lifetimes.
122132298
On the Green's Functions for the Bethe‐Salpeter Equation
Considering the Bethe‐Salpeter equation as a relativistic equation, we have studied the free particle Green's functions for unequal mass scalar bosons, interacting via a translationally invariant potential. The scattering Green's function found by Huang and DeFacio (HD) is presented for all possible Ω‐plane contours for the unequal masses case. Only two k‐plane contours are found to be physically interesting. The causal, advanced, and retarded Green's functions are listed in an appendix for unequal masses for the physical contour. The timelike Green's functions again require severe restrictions on the interaction potential as found by HD, and possible Bethe‐Salpeter bound states are briefly discussed.
122140676
SPIN-1 AND SPIN-2 GAUGE FIELDS IN UNIFIED SL(2N,C) MODELS
121902881
Unified SL(8,C) model of spin-2 gluons and gravitons
A unified version of $f\ensuremath{-}g$ gravity models with Higgs field has been constructed using the SL(8, $C$) group. Leptons and quarks are represented in a four-color scheme using the SU(4) group. When the Higgs fields exhibit a spontaneous breakdown of symmetry in the tree approximation, the spin-2 gluons ($f$) and fermions acquire mass while the graviton ($g$) remains massless. The Higgs-fermion interaction is renormalizable in contrast to the $\mathrm{SL}(2,C)\ensuremath{\bigotimes}\mathrm{SL}(6,C)$ gravity models. The spin-2 gluons include the three-color gluon, an exotic gluon which mixes leptons with hadrons, and a weak gluon which mediates only between leptons.
118335526
TeV SCALE MODELS OF NEUTRINO MASSES AND THEIR PHENOMENOLOGY
We review various TeV scale models for neutrino masses utilizing different types of seesaw mechanisms, higher dimensional operators, expanded gauge symmetries, or low scale extra dimensions. In addition, we discuss the implications of these models for the collider experiments and low energy lepton flavor violation searches.
53540874
Dark matter induced nucleon decay: model and signatures
A bstractIf dark matter (DM) carries anti-baryon number, a DM particle may annihilate with a nucleon by flipping to anti-DM. Inspired by Hylogenesis models, we introduce a single component DM model where DM is asymmetric and carries B and L as -1/2. It can annihilate with a nucleon to an anti-lepton and an anti-DM at leading order or with an additional meson at sub-leading order. Such signals may be observed in proton decay experiments. If DM is captured in the Sun, the DM induced nucleon decay can generate a large flux of anti-neutrinos, which could be observed in neutrino experiments. Furthermore, the anti-DM particle in the final state obtains a relatively large momentum (few hundred MeV), and escapes the Sun. These fast-moving anti-DM particles could also induce interesting signals in various underground experiments.
118612347
Collisions of Jets of Particles from Active Galactic Nuclei with Neutralino Dark Matter
We examine the possibility that energetic Standard Model particles contained in the jets produced by active galactic nuclei (AGN) may scatter off of the dark matter halo which is expected to surround the AGN. In particular, if there are nearby states in the dark sector which can appear resonantly in the scattering, the cross section can be enhanced and a distinctive edge feature in the energy spectrum may appear. We examine bounds on supersymmetric models which may be obtained from the Fermi Gamma-ray Space Telescope observation of the nearby AGN Centaurus A.
54939560
Searching for dilaton dark matter with atomic clocks
We propose an experiment to search for ultralight scalar dark matter (DM) with dilatonic interactions. Such couplings can arise for the dilaton as well as for moduli and axion-like particles in the presence of CP violation. Ultralight dilaton DM acts as a background field that can cause tiny but coherent oscillations in Standard Model parameters such as the fine structure constant and the proton-electron mass ratio. These minute variations can be detected through precise frequency comparisons of atomic clocks. Our experiment extends current searches for drifts in fundamental constants to the well-motivated high-frequency regime. Our proposed setups can probe scalars lighter than 10^-15 eV with discovery potential of dilatonic couplings as weak as 10^-11 times the strength of gravity, improving current equivalence principle bounds by up to 8 orders of magnitude. We point out potential 10^4 sensitivity enhancements with future optical and nuclear clocks, as well as possible signatures in gravitational wave detectors. Finally, we discuss cosmological constraints and astrophysical hints of ultralight scalar DM, and show they are complimentary to and compatible with the parameter range accessible to our proposed laboratory experiments.
121270760
The complex EAS hybrid arrays in Tibet
The Tibet hybrid experiment is an extensive air shower experiment that operated at Yangbajing (E90°31', N30°06'; 4300 m above sea level) in Tibet, China, since 1996. This multi-detector system is used to observe air showers of high energy celestial gamma-ray origin and that of nuclear-component origin. Both observations aim to investigate the origin of cosmic rays using different methods. In this paper, based on the energy spectrum of the nuclear component and its chemical composition around the knee, we would like to discuss whether they could be described by the theoretical picture of the diffusive shock acceleration at SNRs. The consistency of the experimental data with rigidity dependent cutoff spectrum of CRs is examined using Tibet data and KASCADE data. It is found that both experimental data cannot be fully interpreted by such a simple approach. The sharp knee observed by Tibet experiment suggests the contribution of nearby source(s).