Diphoton Higgs signal strength in universal extra dimensions

Abstract

The signal strength of the $gg\to H\to \gamma \gamma$ reaction in $pp$ collisions at the LHC is studied within the context of the SM with UED. The impact of an arbitrary number $n$ of UED on both the $gg\to H$ and $H\to \gamma \gamma$ subprocesses is studied. The 1-loop contributions of Kaluza-Klein excitations to these subprocesses are proportional to discrete and continuous sums, which can diverge. By implementing dimensional regularization, it is shown that discrete regularized sums can naturally be expressed as multidimensional Epstein functions, and that divergences, if exist, emerge through the poles of these functions. It is found that continuous sums converge, but the discrete ones diverge, with the exception of the $n=1$ case, in which the 1-dimensional Epstein function converges. It is argued that divergences that arise from discrete sums for $n\ge 2$ are genuine UV divergences, since they correspond to short-distance effects in the compact manifold. Then, the amplitudes are renormalized in a modern sense by incorporating interactions of canonical dimension higher than four that allow us to generate the required counterterms, which are determined using a $\overline{\mathrm{MS}}$-like renormalization scheme. We find that the $gg\to H$ subprocess is quite sensitive to both the size and the dimension of the compact manifold, but the SM prediction for $H\to \gamma \gamma$ subprocess is practically unchanged. In the $n=1$ case, it is found that the experimental constraint on the compactification scale $R^{-1}\ge 1.5$ TeV allow us to reproduce the experimental limit on the signal strength $1.01\le {\mu }_{\gamma \gamma }^{(1)}\le 1.2$. In the $n\ge 2$ cases, it is found that the experimental limit on ${\mu }_{\gamma \gamma }^{(n)}$ leads to stronger lower bounds for the compactification scale given by $R^{-1}\ge 1.55,2.45,3.57,5.10,7.25$ TeVs for $n=2,4,6,8,10$, respectively.

arXiv comment31 pages, 5 figures

References in corpus (9)

• The Hierarchy Problem and New Dimensions at a Millimeter
• Enhancement of H to gamma gamma from doubly charged scalars in the Higgs Triplet Model
• Higgs boson decays to $\gamma \gamma$ and $Z\gamma$ in models with Higgs extensions
• Nondecoupling of charged scalars in Higgs decay to two photons and symmetries of the scalar potential
• An effective gauge-Higgs operators analysis of new physics associated with the Higgs
• Chiral fermions and gauge-fixing in five-dimensional theories
• Vector bileptons and the decays $h\to \gamma \gamma ,Z\gamma$
• Integration of Kaluza-Klein modes in Yang-Mills theories
• U_e(1)--covariant R_ξ--gauge for the two Higgs doublet model