Non-minimal coupling in Higgs-Yukawa model with asymptotically safe gravity

We study the fixed point structure of the Higgs-Yukawa model, with its scalar being non-minimally coupled to the asymptotically safe gravity, using the functional renormalization group. We have obtained the renormalization group equations for the cosmological and Newton constants, the scalar mass-squared and quartic coupling constant, and the Yukawa and non-minimal coupling constants, taking into account all the scalar, fermion, and graviton loops. We find that switching on the fermionic quantum fluctuations makes the non-minimal coupling constant irrelevant around the Gaussian-matter fixed point with the asymptotically safe gravity.Comment: typos corrected; Accepted for publication in Class. and Quantum Grav.; 50 pages, 5 figures; typos corrected in Eqs. (61), (62), and (79); the last paragraph of Sec. 5.4 added; references added; other minor revision

Hillclimbing Higgs inflation

We propose a realization of cosmic inflation with the Higgs field when the Higgs potential has degenerate vacua by employing the recently proposed idea of hillclimbing inflation. The resultant inflationary predictions exhibit a sizable deviation from those of the ordinary Higgs inflation.Comment: 5 pages, 3 figures, 1 table (v1); published version, references and footnotes added (v2

Diagonal Kaluza-Klein expansion under brane localized potential

We clarify and study our previous observation that, under a compactification with boundaries or orbifolding, vacuum expectation value of a bulk scalar field can have different extra-dimensional wave-function profile from that of the lowest Kaluza-Klein mode of its quantum fluctuation, under presence of boundary-localized potentials which would be necessarily generated through renormalization group running. For concreteness, we analyze the Universal Extra Dimension model compactified on orbifold $S^1/Z_2$, with brane-localized Higgs potentials at the orbifold fixed points. We compute the Kaluza-Klein expansion of the Higgs and gauge bosons in an $R_\xi$-like gauge by treating the brane-localized potential as a small perturbation. We also check that the $\rho$ parameter is not altered by the brane localized potential.Comment: 22 pages, published versio

QCD Effects in the Decays of TeV Black Holes

In models with ``large'' and/or warped extra dimensions, the higher-dimensional Planck scale may be as low as a TeV. In that case black holes with masses of a few TeV are expected to be produced copiously in multi-TeV collisions, in particular at the LHC. These black holes decay through Hawking radiation into typically O(20) Standard Model particles. Most of these particles would be strongly interacting. Naively this would lead to a final state containing 10 or so hadronic jets. However, it has been argued that the density of strongly interacting particles would be so large that they thermalize, forming a ``chromosphere'' rather than well-defined jets. In order to investigate this, we perform a QCD simulation which includes parton-parton scattering in addition to parton showering. We find the effects of parton scattering to remain small for all cases we studied, leading to the conclusion that the decays of black holes with masses within the reach of the LHC will not lead to the formation of chromospheres.Comment: LaTeX with equation.sty (included), 26 pages, 4 figures. Added a few references and one footnot