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.
119125522
Features of warped geometry in presence of Gauss-Bonnet coupling
A bstractWe study the role of the Gauss-Bonnet corrections and two loop higher genus contribution to the gravity action on the Kaluza-Klien modes and their interactions for different bulk fields which enable one to study various phenomenological implications of string loop corrected Gauss-Bonnet modified warped geometry model in one canvas. We have explicitly derived a phenomenological bound on the Gauss-Bonnet parameter so that the required Planck to TeV scale hierarchy can be achieved through the warp factor in the light of recently discovered Higgs like boson at 125GeV. Moreover due to the presence of small perturbative Gauss-Bonnet as well as string loop corrections we have shown that the warping solution can be obtained for both de-Sitter and anti-de-Sitter bulk which is quite distinct from Randall-Sundrum scenario. Finally we have evaluated various interactions among these bulk fields and determined the coupling parameters and the Kaluza-Klien mode masses which is crucial to understand the phenomenology of a string two loop corrected Einstein-Gauss-Bonnet warp geometry.
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.
119307074
DBI Galileon inflation in background SUGRA
Abstract We introduce a model of potential driven DBI Galileon inflation in background N = 1 , D = 4 SUGRA. Starting from D4– D 4 ¯ brane–antibrane in the bulk N = 2 , D = 5 SUGRA including quadratic Gauss–Bonnet corrections, we derive an effective N = 1 , D = 4 SUGRA by dimensional reduction, that results in a Coleman–Weinberg type Galileon potential. We employ this potential in modeling inflation and in subsequent study of primordial quantum fluctuations for scalar and tensor modes. Further, we estimate the major observable parameters in both de Sitter ( DS ) and beyond de Sitter ( BDS ) limits and confront them with recent observational data from WMAP7 by using the publicly available code CAMB.
115768362
Collider constraints on Gauss-Bonnet coupling in warped geometry model
In this paper the requirement of a warp solution in an Einstein-Gauss-Bonnet 5D warped geometry is shown to fix the signature of Gauss-Bonnet coupling ($\alpha_{5}$). Further, imposing the phenomenological constraints, obtained from the recently observed Higgs like scalar mass as well as $\mu$ parameter of the decay channels ${H}_{0}\rightarrow\gamma\gamma,\tau{\bar \tau}$ explored in ATLAS and CMS detectors, we obtain a stringent bound on $\alpha_{5}$ within $(4.8 - 5.1)\times 10^{-7}$.
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 .
10835594
Lepton number violation in a little Higgs model
The Standard Model (SM) has been remarkably successful in explaining experimental data upto the highest energies available at present. The precision electroweak data suggests that the Higgs boson remains light [1], mH < 219 GeV at 95% CL, upto the Planck’s scale. In SM, the Higgs boson however, gets quadratically divergent contribution to its mass and requires fine tuning of parameters which are sensitive to new physics that may be present at scales much higher than electroweak scale. Fine tuning and naturalness requires this new physics to be at the TeV scale. Supersymmetry (SUSY) provides a particularly elegant solution to the Hierarchy problem where quadratic divergences in Higgs mass are canceled between contributions of SM particles and their superpartners. This has the desired effect of stabilizing the electro-weak scale. In Technicolor theories, the hierarchy problem is deferred by introducing new dynamics at a scale not too much above electroweak scale. Theories of large extra dimensions resolve the hierarchy problem by lowering the Planck’s scale and modifying quantum gravity at the TeV scale. Phenomenological consequences of these theories have been studied in the literature and constraints obtained [2]. Recently there has been a proposal to consider Higgs fields as pseudo-Nambu-Goldstone boson of a Global symmetry which is spontaneously broken at some high scale [3]. The Higgs fields acquire mass through electroweak symmetry breaking triggered by radiative corrections leading to Coleman-Weinberg type of potential. Since the Higgs is protected by approximate global symmetry, it remains light and the quadratic divergent contributions to its mass are canceled by the contributions of heavy gauge bosons and a heavy Fermionic state that are introduced in the model. The Littlest Higgs (LH) [3, 4, 5] model is a minimal model of this class which accomplishes this task to one loop order within a minimal matter content. The LH model consists of an SU(5) non-linear sigma model which is spontaneously broken to its subgroup SO(5) by vacuum expectation value (VEV) of order f. The gauged group [SU(2) � U(1)] 2 is broken at the same time to its diagonal electroweak SM sub
16133041
Neutrino lensing and modification of Newtonian gravity at large distances.
The nature of the modification to neutrino lensing from galaxies, as caused by possible modifications to Newtonian gravity at large distances, is studied.
122591411
Regge-Mueller analysis in the pionization region
Abstract We attempt to determine the sub-asymptotic terms in the pionization region of π ± -inclusive reactions by analysing the rapidity dependence of various cross-sections.
53704512
Lepton Number Violation via Intermediate Black Hole Processes
Black holes at the TeV scale are investigated in the extra large dimension scenario. We interpret the lightest black hole excitation as a singlet scalar field, and show how interaction terms can be appended to the standard model at the dimension five non-renormalizable level. Lepton family number violation is natural in this model. Muon magnetic moment, and neutrino masses are investigated. We also present a quantization scheme in n dimensions.
123597715
QUARK MODEL ANALYSIS OF RADIATIVE PION DECAY
We present a relativistic quark model analysis of radiative pion decay using a systematic application of Low’s bremsstrahlung theorem. Our findings agree reasonably with recent definitive experimental results by the Russian group on the structure-dependent components of the πγA and πγV amplitudes, with the latter agreeing remarkably well with the CVC prediction. Finally we analyze between the quark model calculation and the current algebra prediction and establish the equivalence of the two within the limit of a local πqq interaction.