We have previously proposed a light pseudoscalar Higgs boson in the next-to-minimal supersymmetric standard model (NMSSM), the A_1^0, as a candidate to explain the HyperCP observations in Sigma^+ -> p mu^+ mu^-. In this paper we calculate the rates for several other rare decay modes that can help confirm or refute this hypothesis. The first modes we evaluate are K_L -> pi pi A_1^0, which are interesting because they are under study by the KTeV Collaboration. We next turn to eta -> pi pi A_1^0, which are interesting because they are independent of the details of the flavor-changing sector of the NMSSM and may be accessible at DAPhNE. For completeness, we also evaluate Omega^- -> Xi^- A_1^0.
In two recent papers (arXiv:1002.1971 [hep-ph] and arXiv:0911.2460 [hep-ph]) Dermisek and Gunion provide new constraints on a light CP-odd Higgs boson in the framework of the NMSSM (or similar models) based on experimental data from LEP, CLEO, BaBar and CDF experiments. In this brief comment we argue that special care is still needed inside a narrow mass window where mixing with $η_b$ resonances below $B\bar{B}$ can occur. We also stress that observables testing lepton universality and a possible distorsion of the bottomonium mass spectrum can provide an alternative analysis at (Super) B-facto…
In the next-to-minimal supersymmetric model (NMSSM) a light CP-odd Higgs boson is so far allowed by current experiments, which, together with a large tan-beta, may greatly enhance the rare dileptonic decays B-> X_s l^+ l^- and B_s-> l^+ l^- gamma. We examine these decays paying special attention to the new operator allowed by the light CP-odd Higgs boson. We find that in the parameter space allowed by current experiments like LEP II and b-> s gamma, the branching ratios of these rare decays can be greatly enhanced and thus the existing experimental data on B-> X_s mu^+ mu^- can further stringe…
We compute the full next-to-leading order supersymmetric (SUSY) electroweak (EW) and SUSY-QCD corrections to the decays of CP-odd NMSSM Higgs bosons into stop pairs. In our numerical analysis we also present the decay of the heavier stop into the lighter stop and an NMSSM CP-odd Higgs boson. Both the EW and the SUSY-QCD corrections are found to be significant and have to be taken into account for a proper prediction of the decay widths.
In this paper we examine the LHC discovery potential of the lightest CP-odd Higgs boson, a1, of the NMSSM produced in gluon fusion channel gg->a1. We evaluate the inclusive signal rates of the a1 for a variety of decay channels and discuss its possible discovery. It is observed that the overall production and decay rates at inclusive level are quite sizable and should help extracting the a1 signal over some regions of the NMSSM parameter space.
We study here the di-muon decay mode of a very light CP-odd Higgs boson of the NMSSM, a1, produced in association with a bottom-antibottom pair and find that, despite small event rates, a significant signal should be extractable from the SM background at the LHC with high luminosity.
We study the detectability of the lightest CP-odd Higgs boson of the NMSSM, $a_1$, at the LHC through its production in association with a bottom-quark pair followed by the $a_1\to b\bar b$ decay. It is shown that, for large $\tanβ$ and very high luminosity of the LHC, there exist regions of the NMSSM parameter space that can be exploited to detect the $a_1$ through this channel. This signature is a characteristic feature of the NMSSM in comparison to the MSSM, as $a_1$ masses involved are well below those allowed in the MSSM for the corresponding CP-odd Higgs state.
The presence of the light CP-odd scalar boson predicted in the next-to-minimal supersymmetric model (NMSSM) and the simplest little Higgs model (SLHM) dramatically changes the phenomenology of the Higgs sector. We suggest a practical strategy to discriminate the underlying model of the CP-odd scalar boson produced in the decay of the standard model-like Higgs boson. We define the decay rate of "the non $b$-tagged jet pair" with which we compute the ratio of decay rates into lepton and jets. They show much different behaviors between the NMSSM and the SLHM.
Recent BaBar limits on $\br(Υ(3S)\to \gam a\to \gam τ^+τ^-)$ and $\br(Υ(3S)\to \gam a\to \gam μ^+μ^-)$ provide increased constraints on the $a b\anti b$ coupling of a CP-odd Higgs boson, $a$, with $m_a<M_{Υ(3S)}$. We extract these limits from the BaBar data and compare to the limits previously obtained using other data sets, especially the CLEO-III $\br(Υ(1S)\to \gam\toτ^+τ^-)$ limits. Comparisons are made to predictions in the context of "ideal"-Higgs NMSSM scenarios, in which the lightest CP-even Higgs boson, $h_1$, can have mass below $105\gev$ (as preferred by precision electroweak data) a…
Completely natural electroweak symmetry breaking is easily achieved in supersymmetric models if there is a SM-like Higgs boson, $h$, with $m_h\lsim 100\gev$. In the minimal supersymmetric model, such an $h$ decays mainly to $b\anti b$ and is ruled out by LEP constraints. However, if the MSSM Higgs sector is expanded so that $h$ decays mainly to still lighter Higgs bosons, e.g. $h\to aa$, with $BR(h\to aa)>0.7$, and if $m_a<2m_b$, then the LEP constraints are satisfied. In this letter, we show that in the next-to-minimal supersymmetric model the above $h$ and $a$ properties (for the lightest CP…
We study the $Za_1$ decay mode of a heavy CP-even Higgs boson of the NMSSM, $h_2$, where $a_1$ is the lightest CP-odd Higgs state of this scenario, the former produced in association with a bottom-antibottom pair, and find that, despite small event rates, a significant (in fact essentially background free) signal should be extractable at the LHC with very high luminosity, so long that a $Z\to jj$ (where $j$ represents a jet) and $a_1\to τ^+τ^-$ final state is exploited, in presence of $b$-tagging
In the NMSSM, a light CP-odd Higgs arises due to spontaneous breaking of approximate symmetries such as Peccei-Quinn or R-symmetry and is motivated by string theory. The case when it is heavier than two muons is well studied and constrained. We analyze various meson decay, g-2, beam dump and reactor bounds on the CP-odd Higgs with mass below the muon threshold, in particular, addressing the question how light a CP-odd Higgs can be. We find that it has to be heavier than 210 MeV or have couplings to fermions 4 orders of magnitude below those of the Standard Model Higgs. Our analysis applies mor…
We constrain the light CP-odd Higgs $A_{1}^{0}$ in NMSSM via the rare decay $π^{0}\to e^{+}e^{-}$. It is shown that the possible $3σ$ discrepancy between theoretical predictions and the recent KTeV measurement of ${\cal B}(π^{0}\to e^+ e^-)$ cannot be resolved when the constraints from $Υ\toγA_1^0$, $a_μ$ and $π^{0}\to γγ$ are combined. Furthermore, the combined constraints also exclude the scenario involving $m_{A_1^0}=214.3$ MeV, which is invoked to explain the anomaly in the $Σ^{+}\to p μ^{+}μ^{-}$ decay found by the HyperCP Collaboration.
A popular regime in the NMSSM parameter space involves a light CP-odd Higgs $A_1$. This scenario has consequences for e.g. light singlino Dark Matter annihilating in the $A_1$-funnel. In order to confront the pseudoscalar to experimental limits such as flavour observables, Upsilon decays or Beam-Dump experiments, it is necessary to control the interactions of this particle with hadronic matter and derive the corresponding decays. The partonic description cannot be relied upon for masses close to $m_{A_1}\sim1$GeV and we employ a chiral lagrangian, then extended to a spectator model for somewha…
We review the potential of the LHC to detect a very light CP-odd Higgs boson of the NMSSM, $a_1$, through its direct production in association with a bottom-quark pair at large tan$β$. We also review the LHC discovery potential of the two lightest CP-even Higgs states, decaying into two lighter Higgs states or into the lightest CP-odd Higgs state and the $Z$ gauge boson.
We study the Higgs sector of the Next to Minimal Supersymmetric Standard Model (NMSSM) in light of the discovery of the SM-like Higgs boson at the LHC. We perform a broad scan over the NMSSM parameter space and identify the regions that are consistent with current Higgs search results at colliders. In contrast to the commonly studied "decoupling" scenario in the literature where the Minimal Supersymmetric Standard Model CP-odd Higgs boson mass is large mA >> mZ, we pay particular attention to the light Higgs states in the case when mA <~ 2mZ . The Higgs bosons in the NMSSM, namely three CP-eve…
We examine various direct and indirect experimental constraints on the nearly minimal supersymmetric standard model (nMSSM) and obtain the following observations: (i) Current experiments stringently constrain the parameter space, setting a range of 1-37 GeV for the lightest neutralino (LSP), 30-140 GeV (1-250 GeV) for the lightest CP-even (CP-odd) Higgs boson, and 1.5-10 for \tanβ; (ii) To account for the dark matter relic density, besides the s-channel exchange of a Z-boson, the s-channel exchange of a light A_1 (the lightest CP-odd Higgs boson) can also play an important role in LSP annihila…
The next-to minimal supersymmetric standard model (NMSSM) with non-universal Higgs masses, or the semi-constrained NMSSM (scNMSSM), extend the minimal supersymmetric standard model (MSSM) by a singlet superfield and assume universal conditions except for the Higgs sector. It can not only keep the simpleness and grace of the fully constrained MSSM and NMSSM, and relax the tension that they face after the 125-GeV Higgs boson discovered, but also predict an exotic phenomenon that Higgs decay to a pair of light singlet-dominated scalars ($10\!\sim\! 60\;{\rm GeV}$). This condition can be classifie…
We investigate the low energy phenomenology of the lighter pseudoscalar $A_1^0$ in the NMSSM. The $A_1^0$ mass can naturally be small due to a global $U(1)_R$ symmetry of the Higgs potential, which is only broken by trilinear soft terms. The $A_1^0$ mass is further protected from renormalization group effects in the large $\tan β$ limit. We calculate the $b \to s A_1^0$ amplitude at leading order in $\tan β$ and work out the contributions to rare $K$, $B$ and radiative $Υ$-decays and $B -\bar B$ mixing. We obtain constraints on the $A_1^0$ mass and couplings and show that masses down to ${\cal…
We review motivation for a light charged Higgs scenario that occurs in a class of models with a light CP-odd Higgs boson. If the light CP-odd Higgs is doublet-like the charged Higgs is typically lighter than the top quark and it dominantly decays into $W^\pm A$ with $B(H^+ \to W^+ A) > 70%$. We summarize experimental constraints from direct searches and discuss search strategies based on subleading decay modes of the CP-odd Higgs. A search for $t \to H^+ b, \;\;\;\; H^+ \to W^+ A, \;\;\;\; A \to μ^+ μ^- $ could provide an evidence for the charged Higgs or a discovery already with 1 fb$^{-1}$ o…
I will show, via effective field theory (EFT) techniques, that obtaining an observationally consistent relic density while evading stringent direct detection limits and maintaining $h_{125}$ phenomenology in an extended Higgs sector can be easily achieved. I will then map such an EFT to the low energy limit of the NMSSM with the Higgsinos integrated out. Both the singlino and the singlet-like CP-odd and even scalars in the NMSSM may play a relevant role in such a scenario, while being difficult to probe via conventional searches. The singlet sector of the general NMSSM can be mapped on to a 2H…
CP-odd scalars are an integral part of many extensions of the Standard Model. Recently, electroweak-scale pseudoscalars have received increased attention in explaining the diffuse gamma-ray excess from the Galactic Centre. Elusive due to absence of direct couplings to gauge bosons, these particles receive only weak constraints from direct searches at LEP or searches performed during the first LHC runs. We investigate the LHC's sensitivity in observing a CP-odd scalar in di-top associated production in the mass range $20 \leq m_A \leq 100$ GeV using jet substructure based reconstruction techniq…
In the Next-to-Minimal Supersymmetric Standard Model, neutralino dark matter can annihilate into a pair of photons through the exchange of a CP-odd Higgs boson in the s-channel. The CP-odd Higgs boson couples to two photons through a loop of dominantly higgsino-like charginos. We show that the parameter space of the NMSSM can accommodate simultaneously i) neutralino-like dark matter of a mass of about 130 GeV giving rise to a 130 GeV photon line; ii) an annihilation cross section of or larger than 10^{-27}cm^3s^{-1}; iii) a relic density in agreement with WMAP constraints; iv) a direct detecti…
We study possible effects of a light CP-odd Higgs boson on radiative Upsilon decays in the Next-to-Minimal Supersymmetric Standard Model. Recent constraints from CLEO on radiative Upsilon(1S) decays are translated into constraints on the parameter space of CP-odd Higgs boson masses and couplings, and compared to constraints from B physics and the muon anomalous magnetic moment. Possible Higgs - eta_b(nS) mixing effects are discussed, notably in the light of the recent measurement of the eta_b(1S) mass by Babar: The somewhat large Upsilon(1S) - eta_b(1S) hyperfine splitting could easily be expl…
We investigate various classes of Gauge Mediated Supersymmetry Breaking models and show that the Next-to-Minimal Supersymmetric Standard Model can solve the mu-problem in a phenomenologically acceptable way. These models include scenarios with singlet tadpole terms, which are phenomenologically viable, e.g., in the presence of a small Yukawa coupling <~ 10^{-5}. Scenarios with suppressed trilinear A-terms at the messenger scale lead naturally to light CP-odd scalars, which play the rôle of pseudo R-axions. A wide range of parameters of such models satisfies LEP constraints, with CP-even Higgs …
The Next-to-Minimal Supersymmetric Standard Model (NMSSM), the singlet extension of the MSSM which fixes many of the MSSM's shortcomings, is shown to be within reach of the upcoming runs of the Large Hadron Collider (LHC). A systematic treatment of the various Higgs decay channels and their interplay has been lacking due to the seemingly large number of free parameters in the NMSSM's Higgs sector. We demonstrate that due to the SM-like nature of the observed Higgs boson, the NMSSM's Higgs and neutralino sectors have highly correlated masses and couplings and can effectively be described by fou…
We study the rare decay process of $Z$ boson into photon, accompanied by a CP-even or CP-odd scalar. We present the analytical delineation of the processes through the model-independent parametrizations of the new physics couplings and, finally, consider the Next-to-Minimal Supersymmetric Standard Model to mark out the parameter space where the branching fraction can have the maximum value. As a part of the necessary phenomenological and experimental cross-checks, we aim to fit the anomalous magnetic moment of the muon and $W$ boson mass anomaly through the supersymmetric contributions. We als…
We demonstrate that Higgs discovery at the LHC is possible in the context of the NMSSM even for those scenarios such that the only strongly produced Higgs boson is a very SM-like CP-even scalar which decays almost entirely to a pair of relatvely light CP-odd states. In combination with other search channels, we are on the verge of demonstrating that detection of at least one of the NMSSM Higgs bosons is guaranteed at the LHC for accumulated luminosity of $300 {\rm fb}^{-1}$.
We show how the LHC potential to detect a rather light CP-even Higgs boson of the NMSSM, H1 or H2, decaying into CP-odd Higgs states, A1A1, can be improved if Higgs-strahlung off W bosons and (more marginally) off top-antitop pairs are employed alongside vector boson fusion as production modes. Our results should help extracting at least one Higgs boson signal over the NMSSM parameter space.
In the Next-to-Minimal Supersymemtric Standard Model (NMSSM), one of the neutral Higgs scalars (CP-even or CP-odd) may be lighter than half of the SM-like Higgs boson. In this case, the SM-like Higgs boson h can decay into such a light scalar pair and consequently the diphoton and ZZ signal rates at the LHC will be suppressed. In this work, we examine the constraints of the latest LHC Higgs data on such a possibility. We perform a comprehensive scan over the parameter space of the NMSSM by considering various experimental constraints and find that the LHC Higgs data can readily constrain the p…
We explore the potential of the Large Hadron Collider to observe the h1 -> a1 a1 -> 4 muons signal from the lightest scalar Higgs boson (h1) decaying into the two lightest pseudoscalar Higgs bosons (a1), followed by their decays into four muons in the Next-to-Minimal Supersymmetric Standard Model (NMSSM). The signature under study applies to the region of the NMSSM parameter space in which m_a1 < 2 m_tau, which has not been studied previously. In such a scenario, the suggested strategy of searching for a four-muon signal with the appropriate background suppression would provide a powerful meth…
In this paper we briefly review the LHC discovery potential of a light pseudoscalar Higgs boson of the NMSSM, $a_1$, produced in the gluon fusion $gg\to a_1$ , bottom-quark fusion $b\bar b\to a_1$ and bottom-gluon fusion $bg\to ba_1$. We also review the LHC discovery potential of the next-to-lightest CP-even Higgs boson $h_2$ being the non-SM-like Higgs, decaying either into two light CP-odd Higgs bosons $a_1 a_1$ or into a light $a_1$ and the $Z$ gauge boson through the gluon fusion $gg \to h_2$ in the 4$τ$ final state. We find that the light $a_1$ can be detected at the LHC in a variety of p…
We perform a detailed semi-analytical analysis of the electroweak phase transition (EWPT) property in NMSSM, which serves as a good benchmark model in which the 126 GeV Higgs mixes with a singlet. In this case, a strongly first order electroweak phase transition (SFOEWPT) is achieved by the tree-level effects and the phase transition strength $γ_c$ is determined by the vacua energy gap at $T=0$. We make an anatomy of the energy gap at both tree-level and loop-level and extract out a dimensionless phase transition parameter $R_κ\equiv 4 κv_s / A_κ$, which can replace $A_κ$ in the parameterizati…
Various new physics models predict a light CP-odd Higgs boson (labeled as $a$) and open up new decay modes for Z-boson, such as $Z \to \bar{f} f a$, $Z\to aγ$ and $Z\to aaa$, which could be explored at the GigaZ option of the ILC. In this work we investigate these rare decays in several new physics models, namely the type-II two Higgs doublet model (type-II 2HDM), the lepton-specific two Higgs doublet model (L2HDM), the nearly minimal supersymetric standard model (nMSSM) and the next-to-minimal supersymmetric standard model (NMSSM). We find that in the parameter space allowed by current experi…
We consider scenarios in the next-to-minimal supersymmetric model (NMSSM) where the CP-odd and charged Higgs bosons are very light. As we demonstrate, these can be obtained as simple deformations of existing phenomenological MSSM benchmarks scenarios with parameters defined at the weak scale. This offers a direct and meaningful comparison to the MSSM case. Applying a wide set of up-to-date constraints from both high-energy collider and flavour physics, the Higgs boson masses and couplings are studied in viable parts of parameter space. The LHC phenomenology of the light Higgs scenario for neut…
We study the possibility of constructing the NMSSM from the heterotic string. String derived NMSSMs are much more rare than MSSMs due to the extra requirement that there exist a light singlet which couples to the Higgs pairs. They share the common feature that the singlet self-interactions are typically suppressed, leading to either the "decoupling" or the Peccei-Quinn limit of the NMSSM. In the latter case, the spectrum contains a light pseudoscalar which may be relevant to the MSSM fine-tuning problem. We provide a Z_6 heterotic orbifold example of the NMSSM with approximate Peccei-Quinn sym…
Next-to-Minimal Supersymmetric Standard Model neutralino dark matter candidates in the (1-15) GeV range are found with a Markov Chain Monte Carlo scanning code. A very light, singlet-like Higgs and/or CP-odd Higgs is needed in order to achieve such light masses. Light scalar Higgses can yield large direct detection cross sections, suitable for an account of the recent claims for signals. Neutralino annihilations via resonant light pseudoscalar Higgs exchanges can overproduce the indirect yield of gamma-rays from dwarf spheroidal galaxies. Hence, direct and indirect detection experiments probe …
We consider the impact of several flavour-changing observables in the $B$- and the Kaon sectors on the parameter space of the NMSSM, in a minimal flavour violating version of this model. Our purpose consists in updating our previous results in arXiv:0710.3714 and designing an up-to-date flavour test for the public package NMSSMTools. We provide details concerning our implementation of the constraints in a series of brief reviews of the current status of the considered channels. Finally, we present a few consequences of these flavour constraints for the NMSSM, turning to two specific scenarios:…
In this paper, we present the branching ratios of the two lightest CP-even Higgses, $h_1$ and $h_2$, and of the lightest CP-odd Higgs, $a_1$, in the context of the Non-Minimal Supersymmetric Standard Model (NMSSM). We find that for some regions of the parameter space, the branching fractions of $a_1$ into the lightest charginos ($a_1\to χ^+_1χ^-_1)$ and neutralinos ($a_1\to χ^0_1χ^0_1)$ are larger than $50\%$, and can reach a $100 \%$ level in the latter case. Furthermore, the branching ratio of the $h_2\to a_1a_1$ can be equal to unity for all masses of $h_2$ when it is a pure singlet. The ab…
The next-to-minimal supersymmetric model with a light doublet-like CP-odd Higgs boson and small $\tan β$ can satisfy all experimental limits on Higgs bosons even with light superpartners. In these scenarios, the two lightest CP-even Higgs bosons, $\hi$ and $\hii$, and the charged Higgs boson, $\hp$, can all be light enough to be produced at LEP and yet have decays that have not been looked for or are poorly constrained by existing collider experiments. The channel $\hi\to \ai\ai$ (where $\ai$ is the lightest CP-odd boson and has mass below $2m_b$) with $\ai\to τ^+τ^-$ or $2j$ is still awaiting…
We study the parameter space of the semi-constrained NMSSM, compatible with constraints on the Standard Model like Higgs mass and signal rates, constraints from searches for squarks and gluinos, a dark matter relic density compatible with bounds from WMAP/Planck, and direct detection cross sections compatible with constraints from LUX. The remaining parameter space allows for a fine-tuning as low as about 100, an additional lighter Higgs boson in the 60-120 GeV mass range detectable in the diphoton mode or in decays into a pair of lighter CP-odd Higgs bosons, and dominantly singlino like dark …
We investigate the effects of the radiatively-generated tan beta-enhanced Higgs-singlet Yukawa couplings on the decay $Υ\to γA_1$ in the NMSSM, where $A_1$ is the lightest CP-odd scalar. This radiative coupling is found to dominate in the case of a highly singlet Higgs pseudoscalar. The branching ratio for the production of such a particle is shown to be within a few orders of magnitude of current experimental constraints across a significant region of parameter space. This represents a potentially observable signal for experiments at present B-factories.
NMSPEC is a Fortran code that computes the sparticle and Higgs masses, as well as Higgs decay widths and couplings in the NMSSM, with soft SUSY breaking terms specified at MGUT. Exceptions are the soft singlet mass m_s^2 and the singlet self coupling kappa, that are both determined in terms of the other parameters through the minimization equations of the Higgs potential. We present a first analysis of the NMSSM parameter space with universal SUSY breaking terms at MGUT -- except for m_s and A_kappa -- that passes present experimental constraints on sparticle and Higgs masses. We discuss in so…
We explore a scenario in the Next-to-Minimal-Supersymmetric-Standard-Model (NMSSM) with both a light O(10) GeV neutralino and a CP-odd Higgs boson with significant coupling to down-type fermions, evading all current B physics, LEP and WMAP bounds. Motivated by a possible slight lepton universality breaking hinted in Upsilon decays, we consider the effect of the mixing of eta(b) resonances with the pseudoscalar Higgs on the spin-dependent scattering neutralino cross section off nucleons. We conclude that this mechanism could be relevant provided that non-perturbative effects enhance the effecti…
We show the potential of the LHC to detect a CP-even Higgs boson of the NMSSM, $h_1$ or $h_2$, decaying into two rather light CP-odd Higgs bosons, $a_1$, by exploiting the production mode based on Higgs-strahlung off $b$-quarks, i.e., the channel $pp\to b\bar b h_{1,2}$. We also consider the case of $h_2\to h_1 h_1$ decays. It is found that these decays have dominant BRs over large regions of the NMSSM parameter space where tan$β$ is large, a condition which also favours the $pp\to b\bar b h_{1,2}$ production rates. Further decays of the light Higgs boson pairs ($a_1$ and $h_1$) into photon, m…
Naturalness of electroweak symmetry breaking in the next-to-minimal supersymmetric model points to scenarios in which the lightest CP-even Higgs boson has SM-like ZZh coupling and mass m_h ~ 100 GeV and decays partly via h -> b \bar b but dominantly into two CP-odd Higgs bosons, h -> aa, where m_a < 2m_b so that a -> tau+ tau- (or light quarks and gluons) decays are dominant. These preferred scenarios correlate well with the observed excess of events at LEP for m_h ~ 100 GeV.
In the Next-to-Minimal Supersymmetric Standard Model (NMSSM), all singlet-dominated particles including one neutralino, one CP-odd Higgs boson and one CP-even Higgs boson can be simultaneously lighter than about 100 GeV. Consequently, dark matter (DM) in the NMSSM can annihilate into multiple final states to explain the galactic center gamma-ray excess (GCE). In this work we take into account the foreground and background uncertainties for the GCE and investigate these explanations. We carry out a sophisticated scan over the NMSSM parameter space by considering various experimental constraints…
We examine the possibility of electroweak baryogenesis and dark matter in the nMSSM, a minimal extension of the MSSM with a singlet field. This extension avoids the usual domain wall problem of the NMSSM, and also appears as the low energy theory in models of dynamical electroweak symmetry breaking with a so-called fat-Higgs boson. We demonstrate that a strong, first order electroweak phase transition, necessary for electroweak baryogenesis, may arise in regions of parameter space where the lightest neutralino provides an acceptable dark matter candidate. We investigate the parameter space in …
We discuss neutral Higgs boson production through gluon fusion and bottom-quark annihilation in the CP-conserving $\mathbb{Z}_3$-invariant Next-to-Minimal Supersymmetric Standard Model (NMSSM) at proton colliders. For gluon fusion we adapt known asymptotic expansions in supersymmetric particles for the inclusion of next-to-leading order contributions of squarks and gluinos from the Minimal Supersymmetric Standard Model (MSSM) and include electro-weak corrections involving light quarks. Together with the resummation of higher order sbottom contributions in the bottom-quark Yukawa coupling for b…
In the Next-to-Minimal SuperSymmetric Model (NMSSM) the lightest CP-odd Higgs bosons (a1) can be very light. As a consequence, in addition to the standard charged Higgs boson (h+) decays considered in the MSSM for a light charged Higgs (m_h+ < m_t), the branching fraction for h+ to a1 W can be dominant. We investigate how this signal can be searched for in t tbar production at the Large Hadron Collider (LHC) in the case that m_a1 \gtrsim 2m_B with the a1 giving rise to a single b bbar-jet and discuss to what extent the LHC experiments are able to discover such a scenario with an integrated lum…
We explore the prospects for indirect detection of neutralino dark matter in supersymmetric models with an extended Higgs sector (NMSSM). We compute, for the first time, one-loop amplitudes for NMSSM neutralino pair annihilation into two photons and two gluons, and point out that extra diagrams (with respect to the MSSM), featuring a potentially light CP-odd Higgs boson exchange, can strongly enhance these radiative modes. Expected signals in neutrino telescopes due to the annihilation of relic neutralinos in the Sun and in the Earth are evaluated, as well as the prospects of detection of a ne…
The Galactic Center Excess (GCE) is explained in the framework of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) with a $Z_3$ discrete symmetry. We show that a resonant CP-odd Higgs boson with mass twice that of the Dark Matter (DM) candidate is favoured. Meanwhile, the DM candidate is required to have relatively large coupling with the $Z$ boson through its Higgsino component in order to obtain correct DM relic density. Its LHC discovery potential via four signatures is discussed in detail. We find that the most sensitive signals are provided by the Higgsino-like chargino and neutr…
We analyze the stability of the vacuum and the electroweak phase transition in the NMSSM close to the Peccei-Quinn symmetry limit. This limit contains light Dark Matter (DM) particles with a mass significantly smaller than the weak scale and also light CP-even and CP-odd Higgs bosons. Such light particles lead to a consistent relic density and facilitate a large spin-independent direct DM detection cross section, that may accommodate the recently reported signatures at the DAMA and CoGeNT experiments. Studying the one-loop effective potential at finite temperature, we show that when the lighte…
In light of recent remarkable progress in Higgs search at the LHC, we study the rare decay process $h \to Zγ$ and show its correlation with the decay $h \to γγ$ in low energy SUSY models such as CMSSM, MSSM, NMSSM and nMSSM. Under various experimental constraints, we scan the parameter space of each model, and present in the allowed parameter space the SUSY predictions on the $Zγ$ and $γγ$ signal rates in the Higgs production at the LHC and future e+e- linear colliders. We have following observations: (i) Compared with the SM prediction, the $Zγ$ and $γγ$ signal rates in the CMSSM are both sli…
Hidden sector particles with sub-GeV masses like hidden U(1) gauge bosons, the NMSSM CP-odd Higgs, and other axion-like particles are experimentally little constrained as they interact only very weakly with the visible sector. For masses below the muon threshold, we present constraints from meson decays, g - 2 as well as beam-dump and reactor experiments. The NMSSM CP-odd Higgs and generally any pseudoscalar is required to be heavier than 210 MeV or couple to fermions much weaker than the SM Higgs. Hidden photons are less constrained and can be searched for at future fixed-target experiments, …
R-parity violation modifies the phenomenology of supersymmetric models considerably. We study a version of NMSSM, which contains right-handed neutrinos and in which spontaneous R-parity violation is possible. We study the ensuing effects of spontaneous breaking to the Higgs decay modes, taking into account the measured mass of the Higgs boson and experimental constraints, including rare decays. We find that a possible light scalar, dominantly a sneutrino, helps to increase the Standard Model (SM) Higgs-like scalar mass to the measured value. At the same time, a lighter stop than in the MSSM is…
Models with an extended Higgs sector open up the phenomenological possibility of additional scalars, beyond the SM-like boson observed by the LHC, with mass at or below the electroweak scale. Such scenarios are in particular viable in the presence of electroweak-singlet spin-0 fields, as expected for instance in the context of the NMSSM. Given that the size of radiative corrections can substantially affect the Higgs potential, a negative squared mass at the tree level does not necessarily yield a tachyonic spectrum at the physical level, but only indicates a failure of the tree-level descripti…
In the Next-to-Minimal Supersymmetric Standard Model, a bino-like LSP can be as light as a few GeV and satisfy WMAP constraints on the dark matter relic density in the presence of a light CP-odd Higgs scalar. We study upper bounds on the direct detection cross sections for such a light LSP in the mass range 2-20 GeV in the NMSSM, respecting all constraints from B-physics and LEP. The OPAL constraints on e^+ e^- -> χ^0_1 χ^0_i (i > 1) play an important role and are discussed in some detail. The resulting upper bounds on the spin-independent and spin-dependent nucleon cross sections are ~ 10^{-4…
We study the potential of the LHC accelerator, and a future 33 TeV proton collider, to observe the production of a light top squark pair in association with the lightest Higgs boson (${\tilde t}_1 {\tilde t}_1 h_1$), as predicted by the Next-to-Minimal Supersymmetric Standard Model (NMSSM). We scan randomly about ten million points of the NMSSM parameter space, allowing all possible decays of the lightest top squark and lightest Higgs boson, with no assumptions about their decay rates, except for known physical constraints such as perturbative bounds, Dark matter relic density consistent with …
Charged Higgs boson is a crucial prediction of new physics beyond the SM. In this work, we perform a comprehensive scan over the parameter space of NMSSM considering various experimental constraints including the direct search limits from the 13 TeV LHC, and consider the scenario that the next-to-lightest CP-even Higgs boson is SM-like. We find that the masses of charged Higgs bosons can be as light as 350 GeV, the lightest CP-even Higgs boson $h_1$ is predominantly singlet and can be as light as 48 GeV, and the lightest CP-odd Higgs boson $a_1$ is also singlet-dominated and can be as light as…
