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Register a new userLHC phenomenology of light pseudoscalars in the NMSSM
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After the discovery of the 125 GeV Higgs boson, the Next-to-Minimal Supersymmetric Standard Model (NMSSM) has become more interesting as a model for new physics since new tree-level contributions to the Higgs mass makes it easier to accommodate the relatively high measured value, as compared to the MSSM. One very distinctive feature of the NMSSM is the possible existence of a light singlet-like pseudoscalar. As this pseudoscalar may be lighter than the discovered Higgs boson without conflict with data, it may lead to LHC signatures rather different to what is usually searched for in terms of new physics. In these proceedings we will discuss studies concerning the discoverability of such light pseudoscalars. It is demonstrated that heavier scalars decaying to pairs of pseudoscalars or pseudoscalars and Z bosons may lead to discovery in a large part of the parameter space. This is especially important for the non-SM like of the two lightest scalars, as it may have an almost 100% branching ratio for decay into pairs of pseudoscalars. In such a case the discussed channels might be our only means of discovery, also for the scalar.
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The next-to-minimal supersymmetric standard model (NMSSM) with an extended Higgs sector offers one of the Higgs boson as the Standard model (SM) like Higgs with a mass around 125 GeV along with other Higgs bosons with lighter and heavier masses and not excluded by any current experiments. At the LHC, phenomenology of these non SM like Higgs bosons is very rich and considerably different from the other supersymmetric models. In this work, assuming one of the Higgs bosons to be the SM like, we revisit the mass spectrum and couplings of non SM like Higgs bosons taking into consideration all existing constraints and identify the relevant region of parameter space. The discovery potential of these non SM like Higgs bosons, apart from their masses, is guided by their couplings with gauge bosons and fermions which are very much parameter space sensitive. We evaluate the rates of productions of these non SM like Higgs bosons at the LHC for a variety of decay channels in the allowed region of the parameter space. Although bb, {tau}{tau} decay modes appear to be the most promising, it is observed that for a substantial region of parameter space the two-photon decay mode has a remarkably large rate. In this work we emphasize that this diphoton mode can be exploited to find the NMSSM Higgs signal and can also be potential avenue to distinguish the NMSSM from the MSSM. In addition, we discuss briefly the various detectable signals of these non SM Higgs bosons at the LHC.
We explore the detection possibility of light pseudoscalar Higgs boson in the next-to-minimal supersymmetric Standard Model(NMSSM) at the LHC with the center of mass energy, $sqrt{S}=13$ TeV. We focus on the parameter space which provides one of the Higgs boson as the SM-like with a mass of 125 GeV and some of the non-SM-like Higgs bosons can be light having suppressed couplings with fermions and gauge bosons due to their singlet nature. It is observed that for certain region of model parameter space, the singlet like light pseudoscalar can decay to di-photon($gammagamma$) channel with a substantial branching ratio. In this study, we consider this di-photon signal of light pseudoscalar Higgs boson producing it through the chargino-neutralino production and the subsequent decay of neutralino. We consider signal consisting of two photons plus missing energy along with a lepton from the chargino decay. Performing a detailed simulation of the signal and backgrounds including detector effects, we present results for a few benchmark points corresponding to the pseudoscalar Higgs boson mass in the range 60 -100 GeV. Our studies indicate that some of the benchmark points in the parameter space can be probed with a reasonable significance for 100 fb$^{-1}$ integrated luminosity. We also conclude that exploiting this channel it is possible to distinguish the NMSSM from the other supersymmetric models.
Inspired by the fact that relatively small values of the effective higgsino mass parameter of the $Z_3$-symmetric Next-to-Minimal Supersymmetric Standard Model (NMSSM) could render the scenario `natural, we explore the plausibility of having relatively light neutralinos and charginos (the electroweakinos or the ewinos) in such a scenario with a rather light singlino-like Lightest Supersymmetric Particle (LSP), which is a Dark Matter (DM) candidate, and singlet-dominated scalar excitations. By first confirming the indications in the existing literature that finding simultaneous compliance with results from the Large Hadron Collider (LHC) and those from various DM experiments with such light states is, in general, a difficult ask, we proceed to demonstrate, with the help of a few representative benchmark points, how exactly and to what extent could such a highly motivated `natural setup with a singlino-like DM candidate still remains plausible.
We investigate the bounds on light pseudoscalars that arise from a variety of collider searches. Special attention is thereby devoted to the mass regions $[3, 5] , {rm GeV}$ and $[9,11] , {rm GeV}$, in which a meaningful theoretical description has to include estimates of non-perturbative effects such as the mixing of the pseudoscalar with QCD bound states. A compendium of formulas that allows to deal with the relevant corrections is provided. It should prove useful for the interpretation of future LHC searches for light CP-odd spin-0 states.
The electroweak properties of light and charmed D and Ds pseudoscalar mesons are investigated within a unified covariant constituent quark model. The quark-antiquark-meson vertices are assumed to have a symmetric form by the exchange of quark momenta, which is successful in describing the light pseudoscalar meson properties. The flavor decomposition of the elastic electromagnetic form factors, electromagnetic charge radii, and weak decay constants are calculated. Based on the results a discussion on the SU(3) and SU(4) symmetry breaking is made and a comparison with the pion and kaon properties to highlight the Higgs contribution to the structure of these mesons.
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