197509411
Large non-Gaussianities from DBI Galileon and resolution of sensitivity problem
We have studied primordial non-Gaussian features through bispectrum and trispectrum analysis from a model of potential driven DBI Galileon inflation originating from background supergravity and Gauss-Bonnet terms.We have explicitly shown the violation of the widely accepted Maldacena theorem and standard Suyama-Yamaguchi relation in squeezed limit configuration which leads to the resolution of the well-known sensitivity problem between the non-Gaussian parameters ($f_{NL},\tau_{NL},g_{NL}$) and tensor to scalar ratio($r$). Our analysis thus overcomes a generic drawback of the wide class of DBI inflationary models which was, of late, facing tension from observational ground.Hence large primordial non-Gaussianities can be obtained even from single field DBI Galileon and hence these class of models can be directly confronted with the forthcoming results of PLANCK.
118404858
Brane inflation: A field theory approach 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. We have studied extensively reheating phenomenology, which explains the thermal history of the universe and leptogenesis through the production of thermal gravitino pertaining to the particle physics phenomenology of the early universe.
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.
119286198
A step toward exploring the features of Gravidilaton sector in Randall–Sundrum scenario via lightest Kaluza–Klein graviton mass
In this paper we study the role of the 5D Gauss–Bonnet corrections and two-loop higher genus contribution to the gravity action in type IIB string theory inspired low energy supergravity theory in the light of gravidilatonic interactions on the lightest Kaluza–Klein graviton mass spectrum. From the latest constraints on the lightest Kaluza–Klein graviton mass as obtained from the ATLAS dilepton search in 7 TeV proton–proton collision experiments, we have shown that due to the presence of Gauss–Bonnet and string loop corrections, the warping solution in an $$\mathbf{AdS_{5}}$$AdS5 bulk is quite distinct from the Randall–Sundrum scenario. We discuss the constraints on the model parameters to fit with the present ATLAS data.
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 $(4.8 - 5.1)\times 10^{-7}$.
118476324
Inflamagnetogenesis redux: Unzipping sub-Planckian inflation via various cosmoparticle probes
Abstract In this paper I introduce a precise constraint on primordial magnetogenesis, for a generic class of single-field inflationary model followed by small field excursion below the Planck scale. I also establish a connection between the magnetic field at the present epoch and primordial gravity waves (r) via non-vanishing CP asymmetry parameter ( ϵ CP ), which triggers the leptogenesis scenario. Finally, I explore various hidden cosmophenomenological features of theoretical CMB B-mode polarization spectra, which can be treated as a significant probe to put further stringent constraint on low and high scale small field inflationary models after releasing the Planck B-mode polarization data.
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.
16195418
Probing large distance higher dimensional gravity from lensing data
Abstract The modifications induced in the standard weak-lensing formula if Newtonian gravity differs from inverse square law at large distances are studied. The possibility of putting bounds on the mass of gravitons from lensing data is explored. A bound on graviton mass, estimated to be about 100 Mpc −1 is obtained from analysis of some recent data on gravitational lensing.
120954310
The neutron electric dipole moment in the standard KM model
Abstract We compute the electric dipole moment of the neutron in the standard KM model, including the meson-baryon intermediate states which dominate the result in the SU(3) × SU(3) chiral limit, and find 1.4×10−31 e cm⩾|Dn|⩾9.9×10−33 e cm.
15338380
Triviality Bound on Lightest Higgs Mass in NMSSM
We study the implication of triviality on Higgs sector in next to minimal su-persymmetric model (NMSSM) using variational field theory. It is shown that mass of the lightest Higgs boson in NMSSM has an upper bound ∼ 10 M W which is of the same order as that in standard model.
121497646
Variational Approach to Higgs Mass Bound
We present a variational study of the Higgs sector of the standard model (with a single doublet Higgs) regarding it as an effective field theory with an ultraviolet cutoff. Our results yield a maximum value of the Higgs mass about 10.8 times the W-mass.