On two-loop corrections to the Higgs trilinear coupling in models with extended scalar sectors

Abstract

The Higgs trilinear coupling λ hhh is of great importance to understand the structure of the Higgs sector and allows searching for indirect signs of Beyond-the-Standard-Model (BSM) physics, even if new states are somehow hidden. In particular, in models with extended Higgs sectors, it is known that non-decouplings effects in BSM-scalar contributions at one loop can cause λ hhh to deviate significantly from its SM prediction, raising the question of what happens at two loops. We review here our calculation [1, 2] of the leading two-loop corrections to λ hhh in an aligned scenario of a Two-Higgs-Doublet Model. We find their typical size to be 10-20% of the one-loop corrections, meaning that they do not modify significantly the one-loop non-decoupling effects, but are not entirely negligible either. I. INTRODUCTIONThe discovery of the 125-GeV Higgs boson at the CERN LHC in 2012 has been a great success for particle physics, and has completed the particle spectrum of the Standard Model (SM). However, while it is now established that the Higgs sector is responsible for the electroweak symmetry breaking (EWSB), very little is known about the nature of the Higgs potential -in fact, only its minimum and the curvature around the minimum are known. Moreover, although some new physics must exist -possibly not too far from the electroweak (EW) scale -to address shortcomings of the SM, there is so far no clear sign of it in experiments. A first possible explanation for this could be that new physics only exists beyond the scale currently accessible at colliders, and hence their effects would be (almost) impossible to find. Another interesting possibility would be that the new states are made somehow difficult to observe via some symmetry or mechanism.A prime example of the latter is alignment [3], which is defined for models of several Higgs doublets as the limit in which the total EW vacuum expectation value (VEV) is colinear in field a Speaker.

Leading two-loop corrections to the Higgs boson self-couplings in models with extended scalar sectors

“…We begin with a detailed presentation of the calculation of the dominant SM contributions at two loops -these have been shown already in Refs. [72,73]. The two dominant contributions to the two-loop SM effective potential can be taken from e.g.…”

“…In Ref. [73], we also computed two-loop corrections to λ hhh in an aligned 2HDM and in the IDM, but in that respect, we took a slightly different point of view compared to previous works.…”

Exploring anomalous couplings in Higgs boson pair production through shape analysis

“…Refs. [22][23][24][25][26]. Recent phenomenological studies about the precision that could be reached for the trilinear coupling at the (HL-)LHC and future hadron colliders are summarised in Refs.…”

Relic density of dark matter in the inert doublet model beyond leading order: The heavy mass case

“…The majority of these analyses were performed at leading order. A few exceptions where one-loop effects are considered include i) the computation of the tri-linear self coupling of the SM-like Higgs boson [8][9][10], ii) one-loop corrections to the Higgs effective potential [3], the running of the Higgs/scalar masses and the running of the scalar parameters [5] (see also [11]), iii) one-loop induced cross-sections relevant for direct detection [12] and iv) induced one-loop effects for photon production: Higgs decay to a photon pair [13] and DM annihilation to photons [14]. Yet, the relic density of DM as extracted by PLANCK [15] is a precision measurement at the percent level that calls for an equally precise theoretical prediction.…”