119251409
Nonlocal Gravity and Structure in the Universe
The observed acceleration of the Universe can be explained by modifying general relativity. One such attempt is the nonlocal model of Deser and Woodard. Here we fix the background cosmology using results from the Planck satellite and examine the predictions of nonlocal gravity for the evolution of structure in the Universe, confronting the model with three tests: gravitational lensing, redshift space distortions, and an estimator of gravity ${E}_{G}$ that combines spectroscopic information with lensing. Current data favor general relativity (GR) over nonlocal gravity: fixing primordial cosmology with the best fit parameters from Planck leads to weak lensing results favoring GR by 6.8 sigma; redshift space distortions measurements of the growth rate preferring GR by 7.8 sigma; and the single measurement of ${E}_{G}$ favoring GR, but by less than 1 sigma. The significance holds up even after the parameters are allowed to vary within Planck limits. The larger lesson is that a successful modified gravity model will likely have to suppress the growth of structure compared to general relativity.
119287976
Solving the Effective Field Equations for the Newtonian Potential
Loop corrections to the gravitational potential are usually inferred from scattering amplitudes, which seems quite different from how the linearized Einstein equations are solved with a static, point mass to give the classical potential. In this study we show how the Schwinger–Keldysh effective field equations can be used to compute loop corrections to the potential in a way which parallels the classical treatment. We derive explicit results for the one-loop correction from the graviton self-energy induced by a massless, minimally coupled scalar.
118606531
Quantum gravity corrections to the conformally coupled scalar self-mass-squared on de Sitter background
We evaluate one loop quantum gravity corrections to the conformally coupled (CC) scalar self-mass-squared on a locally de Sitter background. In this paper we consider only the conformal-conformal interaction part of the self-mass-squared. This complements the minimal-minimal part worked out in the previous paper [E. O. Kahya and R. P. Woodard, Phys. Rev. D 76, 124005 (2007), arXiv: 0709.0536], and we will add the minimal-conformal part in a follow-up paper to complete the full self-mass-squared at one loop order. The computation is performed using dimensional regularization and the results are fully renormalized by absorbing divergences with counterterms. The finite results can give rise to quantum corrections to the CC scalar mode functions and therefore to their power spectra.
21452649
Scalar Contribution to the Graviton Self-Energy during Inflation
We use dimensional regularization to evaluate the one loop contribution to the graviton self-energy from a massless, minimally coupled scalar on a locally de Sitter background. For noncoincident points our result agrees with the stress tensor correlators obtained recently by Perez-Nadal, Roura, and Verdaguer. We absorb the ultraviolet divergences using the R{sup 2} and C{sup 2} counterterms first derived by 't Hooft and Veltman, and we take the D=4 limit of the finite remainder. The renormalized result is expressed as the sum of two transverse, fourth order differential operators acting on nonlocal, de Sitter invariant structure functions. In this form it can be used to quantum correct the linearized Einstein equations so that one can study how the inflationary production of infrared scalars affects the propagation of dynamical gravitons and the force of gravity.
119239609
Alternate definitions of loop corrections to the primordial power spectra
We consider two different definitions for loop corrections to the primordial power spectra. One of these is to simply correct the mode functions in the tree order relations using the linearized effective field equations. The second definition involves the spatial Fourier transform of the 2-point correlator. Although the two definitions agree at tree order, we show that they disagree at one loop using the Schwinger-Keldysh formalism, so there are at least two plausible ways of loop correcting the tree order result. We discuss the advantages and disadvantages of each.
119207974
Two-field inflation with non-minimal coupling
Motivated by the recent 'Higgs-inflation' scenario based on a single inflaton field, we consider more generic two-field inflation with non-minimal (NM) coupling term. The generic analytic expressions are derived for cosmological observables with the product-separable as well as additive-separable potentials when the NM coupling term is dominated by one of the two fields. A hybrid model of the inflaton potential with a NM coupling , which guarantees the flatness, is closely examined as a concrete example. Compared to the minimal model with K = 0, the NM model is shown to provide better fit to the recent cosmological observation by WMAP9 and Planck2013 with the relatively lower field values during the inflationary epoch. Most interestingly, a small value of tensor-to-scalar ratio requires a large NM coupling in our scenario. The model produces non-observably small non-Gaussianity (NG) in most of parameter space while a large NG is obtainable only when the inflation takes place in a limited field space along the top of the potential.
119216840
Two Higgs doublet models for the LHC Higgs boson data at s$$ \sqrt{s} $$ = 7 and 8 TeV
A bstractUpdated LHC data on the new 126 GeV boson during the 7 and 8 TeV runnings strengthen the standard model Higgs boson interpretation further. Through global χ2 fit analysis, we investigate whether the new particle could be one of the scalar particles in two Higgs doublet models. Four types of the model (I, II, X and Y) are comprehensively studied. Considering the recent analysis on the spin-parity of the new boson, we take two scenarios: it is either the lighter CP-even one or the heavier CP-even one. It is found that the current LHC Higgs data constrain the model quite strongly. Only narrow region along the decoupling line and a separate small island are allowed in Type II, X, and Y. Type I is exceptional with much larger allowed space. We also find that the current data are compatible with the possibility that the light Higgs boson h0 is hidden in the mass window of 90-100 GeV.
119309830
X-ray line signal from 7 keV axino dark matter decay
Article history: Recently a weak X-ray emission around Eγ � 3. 5k eV was detected in the Andromeda galaxy and various galaxy clusters including the Perseus galaxy cluster but its source has been unidentified. Axino, the superpartner of axion, with a mass 2Eγ is suggested as a possible origin of the line with R-parity violating decay into photon and neutrino. Moreover, most of parameter space is consistent with recent observation by the BICEP2 experiment. © 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/). Funded by SCOAP 3 .
119164286
Exact 4-point scattering amplitude of the superconformal Schrödinger Chern-Simons theory
We consider the non-relativistic superconformal U(N) × U(N) Chern-Simons theory with level (k,−k) possessing fourteen supersymmetries. We obtain an exact four-point scattering amplitude of the theory to all orders in 1/N and 1/k and prove that the scattering amplitude becomes trivial when k = 1 and 2. We confirm this amplitude to one-loop order by using an explicit field theoretic computation and show that the beta function for the contact interaction vanishes to the one-loop order, which is consistent with the quantum conformal invariance of the underlying theory.
14893616
Z boson pair production at CERN LHC in a stabilized Randall-Sundrum scenario
We study the Z boson pair production at LHC in the Randall-Sundrum scenario with the Goldberger-Wise stabilization mechanism. It is shown that comprehensive account of the Kaluza-Klein graviton and radion effects is crucial to probe the model: The KK graviton effects enhance the cross section of $g g \to Z Z$ on the whole so that the resonance peak of the radion becomes easy to detect, whereas the RS effects on the $q\bar{q} \to Z Z$ process are rather insignificant. The $p_T$ and invariant-mass distributions are presented to study the dependence of the RS model parameters. The production of longitudinally polarized Z bosons, to which the SM contributions are suppressed, is mainly due to KK gravitons and the radion, providing one of the most robust methods to signal the RS effects. The $1 \sigma$ sensitivity bounds on $(\Lambda_\pi, m_\phi)$ with $k/M_{\rm Pl} =0.1$ are also obtained such that the effective weak scale $\Lambda_\pi$ of order 5 TeV can be experimentally probed.