Singlet-doublet Higgs mixing and its implications on the Higgs mass in the PQ-NMSSM

Abstract

We examine the implications of singlet-doublet Higgs mixing on the properties of a Standard Model (SM)-like Higgs boson within the Peccei-Quinn invariant extension of the NMSSM (PQ-NMSSM). The SM singlet added to the Higgs sector connects the PQ and visible sectors through a PQ-invariant non-renormalizable Kähler potential term, making the model free from the tadpole and domain-wall problems. For the case that the lightest Higgs boson is dominated by the singlet scalar, the Higgs mixing increases the mass of a SM-like Higgs boson while reducing its signal rate at collider experiments compared to the SM case. The Higgs mixing is important also in the region of parameter space where the NMSSM contribution to the Higgs mass is small, but its size is limited by the experimental constraints on the singlet-like Higgs boson and on the lightest neutralino constituted mainly by the singlino whose Majorana mass term is forbidden by the PQ symmetry. Nonetheless the Higgs mixing can increase the SM-like Higgs boson mass by a few GeV or more even when the Higgs signal rate is close to the SM prediction, and thus may be crucial for achieving a 125 GeV Higgs mass, as hinted by the recent ATLAS and CMS data. Such an effect can reduce the role of stop mixing.

Enhanced Higgs associated production with a top quark pair in the NMSSM with light singlets

“…Notice also that in the limitM 2 hH = 0, tth is enhanced forM 2 hsM 2 Hs > 0 (< 0) if the singlet-like scalar is lighter (heavier) than 125 GeV. This is because in this limit mixing of the Higgs with lighter (heavier) singlet-like scalar pushes up (down) the Higgs mass so m 2 h −M 2 hh is positive (negative) [35][36][37]. It is also interesting to note that in principle large cot (β − α) may be also obtained for very heavy non-SM Higgs doublet if |M 2 Hs | is large enough.…”

NMSSM interpretations of the observed Higgs signal

“…Besides the mass prediction in comparison with the MSSM case [18][19][20][21][22][23][24][25], the possibility of modified rates has been discussed, particularly in the diphoton channel [46][47][48][49][50][51][52]. Furthermore, the case of universal (or semi-universal) SUSY-breaking conditions at the GUT scale [53][54][55][56][57][58], gaugemediation [59,60] and other related scenarios [61][62][63][64] have been considered in this context. The CP-violating version of the NMSSM also received some attention [65,66].…”

Impact of an extra gauge interaction on naturalness of supersymmetry

“…This has motivated a great amount of work on various extensions of the MSSM in which new positive contributions to the Higgs mass are present which allow for the 125 GeV Higgs mass without heavy stops. The most notable examples of such models are Next-To-Minimal Supersymmetric Standard Model (NMSSM) [6][7][8][9][10][11][12][13][14] and models with non-decoupling D-terms of some new gauge interactions under which the Higgs is charged [15][16][17][18][19][20][21][22]. However, even if the observed Higgs mass is obtained with light stops the fine-tuning is still present due to constraints on supersymmetric particles, especially on stops and gluino, from direct LHC searches [23,24].…”