Light CP-odd Higgs Boson Research Articles

Review of a Light NMSSM Pseudoscalar Higgs-State Production at the LHC

In this paper, we briefly review the LHC discovery potential of a light pseudoscalar Higgs boson of the NMSSM, a1, produced in the gluon fusion gg→a1, bottom-quark fusion bb¯→a1 and bottom-gluon fusion bg→ba1. We also review the LHC discovery potential of the next-to-lightest CP-even Higgs boson h2 being the non-SM-like Higgs, decaying either into two light CP-odd Higgs bosons a1 or into a light a1 and the Z gauge boson through the gluon fusion gg→h2 in the 4τ final state. We find that the light a1 can be detected at the LHC in a variety of production processes including the gluon fusion, bottom-quark fusion and bottom-gluon fusion. The latter two processes require high luminosity of the LHC and large values of tanβ. We also find that the LHC has the potential to discover the non-SM-like Higgs state, h2, decaying into a pair of light CP-odd Higgses a1’s, allowing the distinguishing of the NMSSM Higgs sector from the MSSM one as such a light a1, is impossible in the latter scenario.

Light CP-odd Higgs boson production of the NMSSM in bottom-gluon fusion at the LHC

We study the [Formula: see text] decay mode of a light CP-odd Higgs boson of the NMSSM, [Formula: see text], produced in bottom-gluon fusion at the LHC. It is shown that for high luminosity of the LHC, there exist regions of the NMSSM parameter space that can be exploited to detect the [Formula: see text] through this channel.

Charged Higgs bosons in the NMSSM under current LHC constraints

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 [Formula: see text] is predominantly singlet and can be as light as 48 GeV, and the lightest CP-odd Higgs boson [Formula: see text] is also singlet-dominated and can be as light as 82 GeV. The charged Higgs bosons mainly decay to [Formula: see text] or [Formula: see text], but the branching ratio of the exotic decays [Formula: see text] and [Formula: see text] can maximally reach 20% and 11%, respectively, which can be used to distinguish the NMSSM from MSSM. Such a heavy charged Higgs boson is inaccessible at the 13 TeV LHC with a luminosity of 36.1 fb[Formula: see text] and its detection needs higher energy and/or higher luminosity.

Search for a Light CP-odd Higgs Boson and Low-Mass Dark Matter at the Belle Experiment.

We report on the first Belle search for a light CP-odd Higgs boson, A^{0}, that decays into low mass dark matter, χ, in final states with a single photon and missing energy. We search for events produced via the dipion transition ϒ(2S)→ϒ(1S)π^{+}π^{-}, followed by the on-shell process ϒ(1S)→γA^{0} with A^{0}→χχ, or by the off-shell process ϒ(1S)→γχχ. Utilizing a data sample of 157.3×10^{6} ϒ(2S) decays, we find no evidence for a signal. We set limits on the branching fractions of such processes in the mass ranges M_{A^{0}}<8.97 GeV/c^{2} and M_{χ}<4.44 GeV/c^{2}. We then use the limits on the off-shell process to set competitive limits on WIMP-nucleon scattering in the WIMP mass range below 5 GeV/c^{2}.

On the D*s and charmonia leptonic decays

Among the different scenarios of New Physics, those with an extended Higgs sector are examined with a lot of attention. Recent experimental observations of several anomalies in flavour physics with respect to expectations of the Standard Model further motivate the effort of phenomenologists. First, informations about the RDs ratio, a test of lepton flavour universality equivalent to RD, already measured, but with the s quark as spectator, are awaited in coming years to constrain the corner of an extended Higgs sector with charged doublets. On another side, leptonic widths of pseudoscalar quarkonia are particularly interesting to test an extended Higgs sector with a light CP-odd Higgs boson singlet, through the study of its mixing with quarkonia states. Hadronic parameters entering those processes have to be determined from lattice QCD with enough confidence on the control of systematic errors. We report on the very first step of a long-term program tackled with Nf = 2 Wilson-Clover fermions to put relevant constraints on extensions of the Higgs sector: extraction of decay constants of D*s, ƞc, ƞc (2S), J/Ψ and Ψ(2S) with lattice ensembles provided by the CLS effort, considering 2 lattice spacings and a large range of pion masses to estimate cut-off effects and extrapolate results to the chiral limit.

Higgs naturalness and dark matter stability by scale invariance

Extending the spacetime symmetries of standard model (SM) by scale invariance (SI) may address the Higgs naturalness problem. In this article we attempt to embed accidental dark matter (DM) into SISM, requiring that the symmetry protecting DM stability is accidental due to the model structure rather than imposed by hand. In this framework, if the light SM-like Higgs boson is the pseudo Goldstone boson of SI spontaneously breaking, we can even pine down the model, two-Higgs-doublets plus a real singlet: The singlet is the DM candidate and the extra Higgs doublet triggers electroweak symmetry breaking via the Coleman–Weinberg mechanism; Moreover, it dominates DM dynamics. We study spontaneously breaking of SI using the Gillard–Weinberg approach and find that the second doublet should acquire vacuum expectation value near the weak scale. Moreover, its components should acquire masses around 380 GeV except for a light CP-odd Higgs boson. Based on these features, we explore viable ways to achieve the correct relic density of DM, facing stringent constraints from direct detections of DM. For instance, DM annihilates into bb¯ near the SM-like Higgs boson pole, or into a pair of CP-odd Higgs boson with mass above that pole.

Searches for light CP-odd Higgs bosons and dark photons at BaBar

Recent results are presented on searches for light CP-odd Higgs bosons and dark photons using data from the BaBar experiment at the PEP II asymmetric energy e+e− collider. The light Higgs bosons are sought via their production in radiative ϒ(1S) decays and their subsequent decays to gg and ss¯ final states. The search for dark photons A′ involves radiative production e+e−→γA′ with A′→e+e− or μ+μ−. No signals are observed.

Searches for a light Higgs and dark photons at BABAR

A light CP-odd Higgs Boson (A0) is predicted in extensions to the Standard Model such as Next-to-Minimal Supersymmetry Standard Model (NMSSM). We search for υ(1S) → γA0; A0 → μ+μ− or τ+τ− and υ(2S,3S) → γA0; A0 → hadrons at BaBar using a sample of 122M υ(3S), 99M υ(2S), and 23M υ(1S). We see no evidence of an NMSSM A0. We also search for dark photons A′ in e+e− → A′h′; h′ → A′A′. We see no evidence of an A′ with 516pb−1 of data.

Trilepton signatures of light charged and CP-odd Higgs bosons in top quark decays

In singlet extensions of the two Higgs doublet model, a light CP-odd Higgs boson (A) can significantly modify decay modes of the charged Higgs, without necessarily affecting decay modes of the standard model-like Higgs boson. These effects can be sizable even if the doublet component of the light CP-odd Higgs is small, so that constraints from Upsilon decays and direct CP-odd Higgs production do not apply. We study a scenario in which the charged Higgs is produced in top quark decays, t -> H+ b, with dominant H+ -> W A. We focus on the CP-odd Higgs mass range below the bb threshold. We summarize all current experimental constraints and find that, as a result of H+ -> W A dominance, this scenario is not constrained in a large region of tan(beta), mH+, and CP-odd Higgs doublet component. We discuss search strategies based on A -> tau tau, with both taus decaying leptonically, and on the subleading decay mode A -> mu mu. We show that a search for t -> H+ b, H+ -> W A, A -> mu mu in 20 fb^-1 of 8 TeV LHC data can constrain most of the currently allowed parameter space. Existing trilepton searches are not sensitive to this signal due to the adopted isolation criteria.

Searches for low-mass Higgs and dark bosons at BaBar

We present BaBar latest results for the direct search of a light CP-odd Higgs boson using radiative decays of the ϒ(nS) (n=1,2,3) resonances in different final states. We also present the results for the search of a hidden sector gauge and Higgs bosons using the full BaBar datasample.

Closing the Window on Light Charged Higgs Bosons in the NMSSM

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 (mh±&lt;mt), the branching fraction forh±→a1Wcan be dominant. We investigate how this signal can be searched for intt-production at the Large Hadron Collider (LHC) in the case that (ma1≳2mB) with thea1giving rise to a singlebb--jet and discuss to what extent the LHC experiments are able to discover such a scenario with an integrated luminosity ~20 fb−1. We also discuss the implications of the possible Higgs-signal observed at the LHC.

A Comparative Study of Dark Matter in the MSSM and Its Singlet Extensions: A Mini Review

In this note we briefly review the recent studies of dark matter in the MSSM and its singlet extensions: the NMSSM, the nMSSM, and the general singlet extension. Under the new detection results of CDMS II, XENON, CoGeNT, and PAMELA, we find that (i) the latest detection results can exclude a large part of the parameter space which is allowed by current collider constraints in these models. The future SuperCDMS and XENON can cover most of the allowed parameter space; (ii) the singlet sector will decouple from the MSSM-like sector in the NMSSM; however, singlet sector makes the nMSSM quite different from the MSSM; (iii) the NMSSM can allow light dark matter at several GeV to exist. Light CP-even or CP-odd Higgs boson must be present so as to satisfy the measured dark matter relic density. In case of the presence of a light CP-even Higgs boson, the light neutralino dark matter can explain the CoGeNT and DAMA/LIBRA results; (iv) the general singlet extension of the MSSM gives a perfect explanation for both the relic density and the PAMELA result through the Sommerfeld-enhanced annihilation. Higgs decays in different scenario are also studied.

Formula omitted] at BaBar: new physics searches with lepton flavor violation, lepton universality, or final states with τ leptons

The datasets collected at the ϒ ( 3 S ) and ϒ ( 2 S ) energies have recently allowed the BaBar experiment to obtain several important results in the search for direct and indirect new physics effects. In particular, new limits on lepton flavor violating decays of the ϒ ( 3 S ) and ϒ ( 2 S ) , on the ratio Γ ( ϒ ( 1 S ) → τ + τ − ) / Γ ( ϒ ( 1 S ) → μ + μ − ) , and on searches for a light CP-odd Higgs boson decaying into final states with τ leptons are presented.

Possible lepton universality breaking in Upsilon decays: a light CP-odd Higgs interpretation and consequences

A light CP-odd Higgs boson mixing with η b hadronic resonances can show up by inducing a slight but observable lepton universality breaking in Upsilon decays. Besides, hyperfine splittings m ϒ ( n S ) − m η b ( n S ) might also be sensitive to the mixing providing another hint of the existence of such a light pseudoscalar Higgs. On the other hand, recent findings from astroparticle and cosmology favouring a light dark matter constituent (with mass about 10 GeV or less) cast a new interest into the search for invisible decays of ϒ resonances performed at B factories.

Reinforcing the no-lose theorem for NMSSM Higgs discovery at the LHC

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$\beta$ 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, muon, tau and $b$ final states are also considered. The overall production and decay rates for these processes at inclusive level are sizable and should help extracting at least one Higgs boson signal over the NMSSM parameter space.

Search for a Very LightCP-Odd Higgs Boson in Top Quark Decays frompp¯Collisions ats=1.96 TeV

We present the results of a search for a very light CP-odd Higgs boson a10 originating from top quark decays t→H±b→W±(*)a10b, and subsequently decaying into τ+τ−. Using a data sample corresponding to an integrated luminosity of 2.7 fb−1 collected by the CDF II detector in pp¯ collisions at 1.96 TeV, we perform a search for events containing a lepton, three or more jets, and an additional isolated track with transverse momentum in the range 3 to 20 GeV/c. Observed events are consistent with background sources, and 95% C.L. limits are set on the branching ratio of t→H±b for various masses of H± and a10.Received 2 May 2011DOI:https://doi.org/10.1103/PhysRevLett.107.031801© 2011 American Physical Society

Reduced branching ratio for H → AA → 4 τ from A − η b mixing

Models with an extended Higgs sector, as the NMSSM, allow for scenarios where the Standard Model-like CP-even Higgs boson H decays dominantly as H → AA → 4τ where A is a light CP-odd Higgs boson. Tight constraints on this scenario in the form of lower bounds on M H have recently been published by the ALEPH group. We show that, due to A − η b mixing, the branching ratio H → AA → 4τ is strongly reduced for M A in the range 9–10.5 GeV. This is the range of M A in which the tension between the observed η b (1S) mass and its prediction based on QCD can be resolved due to mixing, and which is thus still consistent with a light CP-even Higgs boson H satisfying LEP constraints with a masswellbelow114GeV. This result is practically independent from the coupling of A to b quarks.

Low mass Higgs signals at the LHC in the Next-to-Minimal Supersymmetric Standard Model

In the NMSSM, because of introducing a complex singlet superfield, the lightest CP-odd Higgs boson, $a_1$, can be a singlet-like state with a tiny doublet component in large regions of parameter space. In this paper, we examine the discovery potential of $a_1$ produced in association with a bottom-antibottom pair at the LHC through $\tau^+\tau^-$ and $\gamma\gamma$ decay modes. It is shown that an $a_1$ with mass $\leq M_Z$ can be extracted from the SM backgrounds by using the $\tau^+\tau^-$ decay channel, a possibility precluded to the MSSM. In contrast, the $\gamma\gamma$ decay mode is overwhelmed by backgrounds despite the fact that the branching ratio of this mode can reach unity when $a_1$ is a pure singlet.

Muon signals of very lightCP-odd Higgs states of the NMSSM at the LHC

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.

Rare Z-decay into light CP-odd Higgs bosons: a comparative study in different new physics models

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 \( Z \to \bar{f}fa \), Z → aγ and Z → 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 experiments, the branching ratios can reach 10−4 for \( Z \to \bar{f}fa (f = b,\tau)\), 10−9 for Z → aγ and 10−3 for Z → aaa, which implies that the decays \( Z \to \bar{f}fa \) and Z → aaa may be accessible at the GigaZ option. Moreover, since different models predict different patterns of the branching ratios, the measurement of these rare decays at the GigaZ may be utilized to distinguish the models.