96425170
Structure formation in a nonlocally modified gravity model
We study a nonlocally modified gravity model proposed by Deser and Woodard which gives an explanation for current cosmic acceleration. By deriving and solving the equations governing the evolution of the structure in the Universe, we show that this model predicts a pattern of growth that differs from standard general relativity (+dark energy) at the 10-30% level. These differences will be easily probed by the next generation of galaxy surveys, so the model should be tested shortly.
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.
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.
118577921
The volume of the past light-cone and the Paneitz operator
We study a conjecture involving the invariant volume of the past light-cone from an arbitrary observation point back to a fixed initial value surface. The conjecture is that a fourth order differential operator which occurs in the theory of conformal anomalies gives 8π when acted upon the invariant volume of the past light-cone. We show that an extended version of the conjecture is valid for an arbitrary homogeneous and isotropic geometry. First order perturbation theory about flat spacetime reveals a violation of the conjecture which, however, vanishes for any vacuum solution of the Einstein equation. These results may be significant for constructing quantum gravitational observables, for quantifying the back-reaction on spacetime expansion and for alternate gravity models which feature a timelike vector field.
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.
14552682
Probing large extra dimensions with spin configuration of top quark pair production at the JLC
We explore signatures of large extra dimensions with a polarized electron/positrn beam at the Joint Linear Collider (JLC). We point out that spin informations can be useful to study indirect signals for large extra dimensions due to spin-2 nature of Kaluza-Klein gravitons. The spin configurations of the top quark pair production at e + e and γγ collisions provide an unique testing ground to search for effects of the large extra dimensions. Especially we show the forward-backward ~
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.
119112331
W' in new physics models at the LHC
We study the new heavy charged gauge boson W' in various models including Left-Right symmetric, Little Higgs, Randall-Sundrum and universal extra dimension model considering pp \rightarrow W' \rightarrow lepton + neutrino with the 7 TeV and 14 TeV CM energies at the LHC. Of particular, we show that the universal extra dimension model is highly constrained by existing and forthcoming data.
2323759
Orbifold GUT inflation
We consider a scenario of cosmological inflation coming from a grand unified theory in higher-dimensional orbifold. Flatness of the potential is automatically guaranteed in this orbifold set-up thanks to the nonlocality of the Wilson line on higher dimensions and the local quantum gravitational corrections are exponentially suppressed. The spectral index of scalar perturbation () and a significant production of gravitational waves are predicted () in the perturbative regime of gauge interaction (1/g4 = (5–20) × 2πRMPl) where the size of compactification is constrained (–45) by the measurement of the scalar power spectrum ().
118307706
Hawking radiation of mini black holes at colliders: Determination of BH evolution
In the series of papers by Ida, Oda and Park, the complete description of Hawking radiation to the brane localized Standard model fields from mini black holes in the low energy gravity scenarios are obtained. In this proceedings, we briefly review what we have learned in those papers.