56438320
The possibility of meson-lepton and dilepton resonances
Recent hints in experimental data of a fJ.1T resonance at 429 MeV have led us to speculate about the possibility of meson-lepton and dilepton resonances. We show that the proposed fJ.7T resonance at 429 MeV is not in conflict with the muon g-2 measurements, and that it could be interpreted as a partner of the excited charged leptons possibly seen at CERN. Moreover, a composite model by Fritzsch and Mandelbaum predicts not only a flavour octet of meson-muon resonances of which this could be one, but also dilepton resonances which were suggested by Ramm as an explanation of the lobe structure in the fJ.7T data. The observed widths and branching ratios of the resonances can be interpreted to suggest that the colour-octet states are considerably smaller than the colour singlets.
125314068
Supersymmetric effects in B(s) ---> l+ l- gamma decays
122154027
Relativistic oscillator in a Bethe-Salpeter model: Nonexistence of discrete bound states
We investigate the solutions of the covariant Bethe-Salpeter equation for bound states of a scalar quark-antiquark system with an effective confining kernel which in coordinate four-space behaves as ${R}^{2}$. Using a suitable set of new variables we separate the equation into one-dimensional equations and study the eigenvalue problem. We find that the covariant bound-state Bethe-Salpeter equation with the above kernel possesses only a continuous spectrum.
121960660
Neutral-current cross sections for double-pion production by neutrinos
We have derived expressions for the differential cross sections for two-pion production by the neutral current in a neutrino-induced hadron reaction. We assume a general V, A form of the neutral current with arbitrary admixture of isotopic scalar and vector parts and utilize the algebra of currents and the PCAC (partial conservation of the axial-vector current) hypothesis to obtain the amplitude for ..nu.. + N ..-->.. ..nu.. + N + ..pi.. + ..pi... Two different cases have been studied: (i) Both the outgoing pions are at threshold. (ii) They are produced via the formation of N*. The results are useful to examine the structure of the neutral current.
118238640
HIGH-ORDER LOW-ENERGY THEOREMS FOR NUCLEON COMPTON SCATTERING.
The well-known zero- and first-order (in photon energy) low-energy theorems for nucleon Compton scattering have recently been derived by Abarbanel and Goldberger using only the physical helicity amplitudes for the process and exploiting their kinematical singularities and zeros. We use this approach to study higher-order terms in photon energy and find the result, not entirely new, that four of the six independent helicity amplitudes are determined in second order by the mass, charge, and magnetic moment of the nucleon. Therefore, these parameters together with two structure-dependent constants, which can be interpreted approximately as electric and magnetic polarizabilities, completely determine the Compton scattering to second order in energy. Similar simplifications occurring in the structure of higher-order terms in energy are also discussed. The kinematical singularity structure of helicity amplitudes is a manifestation of Lorentz invariance. We claim to have fully exploited the requirements of Lorentz invariance and therefore to have derived the complete set of low-energy theorems for this process.
10367884
Comment on "New interaction for the enhancement of the Delta I=1/2 amplitude in weak decays"
56030556
Primordial blackholes and gravitational waves for an inflection-point model of inflation
Abstract In this article we provide a new closed relationship between cosmic abundance of primordial gravitational waves and primordial blackholes that originated from initial inflationary perturbations for inflection-point models of inflation where inflation occurs below the Planck scale. The current Planck constraint on tensor-to-scalar ratio, running of the spectral tilt, and from the abundance of dark matter content in the universe, we can deduce a strict bound on the current abundance of primordial blackholes to be within a range, 9.99712 × 10 − 3 Ω PBH h 2 9.99736 × 10 − 3 .
118378176
Brane inflation in background supergravity
We propose a model of inflation in the framework of brane cosmology driven by background supergravity. Starting from bulk supergravity we construct the inflaton potential on the brane and employ it to investigate for the consequences to inflationary paradigm. To this end, we derive the expressions for the important parameters in brane inflation, which are somewhat different from their counterparts in standard cosmology, using the one loop radiative corrected potential. We further estimate the observable parameters and find them to fit well with recent observational data by confronting with WMAP7 using CAMB. We also analyze the typical energy scale of brane inflation with our model, which resonates well with present estimates from cosmology and standard model of particle physics.
119262207
Higgs inflation from new Kähler potential
Abstract We introduce a new class of models of Higgs inflation using the superconformal approach to supergravity by modifying the Kahler geometry. Using the above-mentioned mechanism, we construct a phenomenological functional form of a new Kahler potential followed by construction of various types of models which are characterized by a superconformal symmetry breaking parameter χ . Depending on the numerical values of χ we classify the proposed models into three categories. Models with minimal coupling are identified by χ = ± 2 3 branch which are made up of shift symmetry preserving flat directions. We also propose various other models by introducing a non-minimal coupling of the inflaton field to gravity described by χ ≠ 2 3 branch. We employ all these proposed models to study the inflationary paradigm by estimating the major cosmological observables and confront them with recent observational data from WMAP9 along with other complementary data sets, as well as independently with PLANCK. We also mention an allowed range of non-minimal couplings and the Yukawa type of couplings appearing in the proposed models used for cosmological parameter estimation.
119187831
Reheating and leptogenesis in a SUGRA inspired brane inflation
Abstract We have studied extensively phenomenological implications in a specific model of brane inflation driven by background supergravity (Choudhury and Pal, 2011) [1] , via thermal history of the universe and leptogenesis pertaining to the particle physics phenomenology of the early universe. Using the one loop corrected inflationary potential we have investigated for the analytical expression as well as the numerical estimation for brane reheating temperature for standard model particles. This results in some novel features of reheating from this type of inflation which have serious implications in the production of heavy Majorana neutrinos needed for leptogenesis through the reheating temperature. We have also derived the expressions for the gravitino abundance during reheating and radiation dominated era. We have further estimated different parameters at the epoch of phase transition and revealed their salient features. At the end we have explicitly given an estimate of the amount of CP violation through the effective CP phase which is related to baryon asymmetry as well as gravitino dark matter abundance.
119168535
Fourth level MSSM inflation from new flat directions
We propose a model of inflation driven by minimal extension of SUSY, commonly known as MSSM. Starting from gauge invariant flat directions in the n = 4 level comprising of QQQL,QuQd,QuLe and uude, we construct the inflaton potential and employ it to investigate for its consequences around the saddle point arising from the non-vanishing fourth derivative of the original potential. To this end, we derive the expressions for the important parameters in MSSM inflation using the loop corrected potential. We further estimate the observable parameters and find them to fit well with recent observational data from WMAP7 by using the code CAMB. We also explore the possibility of primordial black hole formation from our model. Finally, we analyze one loop RGE and compute different phenomenological parameters which could be precisely determined in LHC or future Linear Colliders.