Higgs boson decays intoγγandZγin the MSSM and theB−Lsupersymmetric SM

Abstract

We calculate Higgs decay rates into γγ and Zγ in the Minimal Supersymmetric Standard Model (MSSM) and (B-L) Supersymmetric Standard Model (BLSSM) by allowing for contributions from light staus and charginos. We show that sizable departures are possible from the SM predictions for the 125 GeV state and that they are testable during run 2 at the Large Hadron Collider. Furthermore, we illustrate how a second light scalar Higgs signal in either or both these decay modes can be accessed at the CERN machine rather promptly within the BLSSM, a possibility instead precluded to the MSSM owing to the much larger mass of its heavy scalar state.The strongest experimental evidence of Higgs boson discovery at the Large Hadron Collider (LHC) emerged from its decay channels into γγ and ZZ. Although these decays are at present largely consistent with the Standard Model (SM) predictions, one finds that the signal strength of the di-photon decay mode is larger than the SM expectation by an ≈ 2σ deviation [1,2]. While this effect may well be compatible with the SM, the difference calls for close scrutiny, as a Higgs decay into di-photons is a loop-mediated process, thus subject to Beyond the SM (BSM) effects entering at the same perturbative level as the SM ones. Hence, it may well be regarded as a possible hint of new physics. In addition, both ATLAS [3] and CMS [4] reported upper bounds for the Zγ decay rate which are one order of magnitude larger than the SM expectation, thereby not eliminating the possibility of deviations from the SM in this channel either. Indeed, just like γγ, also Zγ is induced by loops wherein BSM particles may enter alongside the SM ones. Therefore, both such decay channels are key to understand the nature of the SM-like Higgs boson discovered at CERN in July 2012 and they will be analysed very thoroughly in the second LHC run.A common feature of the γγ and Zγ decay modes is that they are both primarily mediated by W -boson and t-quark loops, which are of opposite sign and with the former dominanting the latter, so that, upon accounting for the dominance of the h → W W decay starting from ≈ 160 GeV, one finds that the corresponding Branching Ratios (BRs) tend to be largest below the W W threshold, say, around 130 and 150 GeV, respectively. Another peculiarity of these two decay modes is that any contribution to the γγ channel will affect the Zγ one as well. The vice versa is not true though. For example, scenarios with a Z boson which can mix with the Z state of the SM would affect the latter but not the former. A spectacular situation which would definitely hint at new physics is, for example, the one where the SM-like Higgs decay rate into Zγ is measured to be larger than the one in γγ. Recall in fact that for the Higgs boson of the SM with a 125 GeV mass one has that Γ(h → γγ) > Γ(h → Zγ). Needless to say, the discovery of another Higgs boson signal, in γγ, Zγ or else, would be a clear evidence for a BSM nature of Electro-Weak Symmetry Breaking (EWSB).Amongst models of Supersymmetry (SUSY), a theory we...

General one-loop formulas for decay $$h\rightarrow Z\gamma $$ h → Z γ

“…where all PV functions having divergence completely disappeared, and therefore d = 4. We would like to emphasize now that formula (14) is written in terms of PV functions which are contained in LoopTools and hence it can be easily evaluated numerically. Moreover, analytic expressions for the relevant PV functions have been constructed [10,48], that is enough to implement our results in existing numerical programs or to write a new stand-alone code.…”

“…Meanwhile, another loopinduced coupling h Zγ related to the decay h → Z γ has not been measured yet even so that the predicted decay rate is of the same order as the one of h → γ γ in the SM case [5]. The partial decay width h → Z γ was calculated within the SM framework and its supersymmetric extension [6][7][8][9][10][11][12][13][14]. From the experimental side, this decay channel is now been searched at the LHC by both CMS and ATLAS collaboraa e-mail: lthue@iop.vast.ac.vn b e-mail: arbuzov@theor.jinr.ru c e-mail: tthong@agu.edu.vn d e-mail: thanhphong@ctu.edu.vn e e-mail: dangtrungsi@cantho.edu.vn f e-mail: hoangngoclong@tdtu.edu.vn e Corresponding author tions [15][16][17].…”

Search for mono-Higgs signals at the LHC in the B−L supersymmetric standard model

“…Wherever a Z is present in the MSSM, a Z ′ can also contribute. Furthermore, for each of the neutral MSSM Higgs states, h, H and A, there corresponds in the BLSSM a primed version, h ′ , H ′ and A ′ , wherein the h ′ can have a mass similar to the h one (i.e., just above 125 GeV) while the other two states are generally much heavier [10,[20][21][22], most notably in its inverse seesaw version [9]. Hence, the potential to increase the sensitivity of experimental analyses is twofold.…”

Can We Have a Second Light Higgs Boson in the LHC Data?

“…1. Before closing, we should also mention that the h → γγ enhancement found in the BLSSM may be mirrored in the γZ decay channel [15] for which, at present, there exists some constraints, albeit not as severe as in the γγ case. Doubtless, if the second peak is real, explanations for it can be found in other SUSY models than just the BLSSM.…”

“…[14] (see also [15]), wherein, motivated by a ∼ 2.9σ excess recorded by the CMS experiment at the LHC around a mass of order ∼ 140 GeV in ZZ * → 4l and γγ samples, is was shown that a double Higgs peak structure can be generated in the BLSSM, with CP-even Higgs boson masses at ∼ 125 and ∼ 140 GeV, a possibility instead precluded to the MSSM. Before proceeding in this respect, though, two remarks are in order: firstly, ifg = 0, the coupling of the BLSSM lightest Higgs state, h , with the SM particles will be significantly suppressed (≤ 10 −5 relative to the SM strength), so that, in order to account for possible h signals at the LHC, this parameter ought to be sizable; secondly, in both cases of vanishing and non-vanishingg, one may fine-tune the parameters and get a light m A , which leads to a MSSM-like CP-even Higgs state, H, with m H ∼ 140 GeV.…”