CP-odd Higgs Boson Research Articles

A 130 GeV photon line from dark matter annihilation in the NMSSM

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 cm3 s−1; iii) a relic density in agreement with WMAP constraints; iv) a direct detection cross section compatible with bounds from XENON100, and v) a Standard Model like Higgs mass of about 125 GeV. However, the CP-odd Higgs mass has to lie accidentally close to 260 GeV.

Radiative corrections to electroweak parameters in the Higgs triplet model and implication with the recent Higgs boson searches

We study radiative corrections to the electroweak parameters in the Higgs model with the Y=1 triplet field, which is introduced in the scenario of generating neutrino masses based on the so-called type II seesaw mechanism. In this model, the rho parameter deviates from unity at the tree level. Consequently, the electroweak sector of the model is described by the four input parameters such as $\alpha_{\text{em}}$, $G_F$, $m_Z$ and $\sin^2\theta_W$. We calculate the one loop contribution to the W boson mass as well as to the rho parameter in order to clarify the possible mass spectrum of the extra Higgs bosons under the constraint from the electroweak precision data. We find that the hierarchical mass spectrum among $H^{\pm\pm}$, $H^{\pm}$ and $A$ (or $H$) is favored by the precision data especially for the case of $m_A$ $(\simeq m_H)>m_{H^+}>m_{H^{++}}$, where $H^{\pm\pm}$, $H^{\pm}$, $A$ and $H$ are the doubly-charged, singly-charged, CP-odd and CP-even Higgs bosons mainly originated from the triplet field. We also discuss phenomenological consequences of such a mass spectrum with relatively large mass splitting. The decay rate of the Higgs boson decay into two photons is evaluated under the constraint from the electroweak precision data, regarding the recent Higgs boson searches at the CERN LHC.

Cosmology of the DFSZ axino

We study the cosmological impact of the supersymmetric DFSZ axion model.Extending recent works, we first provide a comprehensive analysisof thermal production of the DFSZ axino considering all the possible scattering,decay and inverse decay processes depending on various mass parameters and the reheat temperature.Although it is hard for the DFSZ axino to be in thermal equilibrium,its coupling is still large enough to generate huge axino population whichcan turn into overabundant neutralino density.We examine the neutralino parameter space to identify the dark matter property depending onthe Peccei-Quinn scale. As the Peccei-Quinn scale becomes higher resulting inlonger axino lifetime,the neutralino dark matter appearsin a lighter Higgsino-like LSP region or a more restricted Bino-like LSP regionallowing a resonant annihilation through a CP-odd Higgs boson to meet strongerreannihilation.

Light dark matter and the electroweak phase transition in the NMSSM

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 lightest CP-even Higgs mass is of the order of a few GeV, the electroweak phase transition tends to become first order and strong. The inverse relationship between the direct-detection cross-section and the lightest CP-even Higgs mass implies that a cross-section of the order of 10$^{-41}$ cm$^2$ is correlated with a strong first order phase transition.

LHC constraints on Yukawa unification in SO(10)

Abstract LHC constraints on the recently proposed SUSY SO(10) GUT model with top-bottom-tau Yukawa unification are investigated. In this model, various phenomenological constraints are in concord with the Yukawa unification thanks to the negative sign of μ, D-term splitting in the soft scalar masses and non-universal gaugino masses generated by a non-zero F -term in a 24-dimensional representation of SU(5) ⊂ SO(10). After discussing the impact of the CP-odd Higgs boson mass bound on this model, we provide a detailed analysis of the recent direct SUSY searches performed by ATLAS and investigate the constraints on this SO(10) model. At 95% confidence level, the lower limit on the gluino mass is found to be 675 GeV. Assuming an integrated luminosity of 10 fb−1, this bound may be extended to 1.1 TeV if the right-handed down squark is lighter than about 1 TeV.

The second Kaluza–Klein mode of CP-odd neutral Higgs boson in the minimal universal extra dimension model

Loop-induced decays of a neutral standard model (SM) Higgs boson into a pair of gluons or photons are very suppressed if the Higgs boson is heavy (≳500 GeV). In the minimal universal extra dimension model, these radiative decays can be significant for the second Kaluza–Klein (KK) mode of the CP-odd Higgs boson, χ(2). We find that the CP-even KK Higgs boson has vanishing decay rate of h(2)→gg at one-loop level: the h(2) production at the LHC is very suppressed. On the contrary, the process gg→χ(2)→γγ in an optimal scenario can be observed with manageable SM backgrounds 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.

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±<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.

Gluon-fusion contributions toΦ+2jet production

In high energy hadronic collisions a scalar or pseudoscalar Higgs boson, Phi=H,A, can be efficiently produced via gluon fusion, which is mediated by heavy quark loops. We here consider double real emission corrections to Phi=A production, which lead to a Higgs plus two-jet final state, at order alpha_s^4. Full quark mass effects are considered in the calculation of scattering amplitudes for the CP-odd Higgs boson A, as induced by quark triangle-, box- and pentagon-diagrams. They complement the analogous results for a CP-even Higgs boson H in Ref.[1]. Interference effects between loops with top and bottom quarks as well as between CP-even and CP-odd couplings of the heavy quarks are fully taken into account.

Production of scalar and pseudo-scalar Higgs bosons to next-to-next-to-leading order at hadron colliders

We consider the production of intermediate-mass CP-even and CP-odd Higgs bosons in proton-proton and proton-anti-proton collisions. We extend the recently published results for the complete next-to-next-to-leading order calculation for a scalar Higgs boson to the pseudo-scalar case and present details of the calculation that might be useful for similar future investigations. The result is based on an expansion in the limit of a heavy top quark mass and a subsequent matching to the expression obtained in the limit of infinite energy. For a Higgs boson mass of 120 GeV the deviation from the infinite-top quark mass result is small. For 300 GeV, however, the next-to-next-to-leading order corrections for a scalar Higgs boson exceed the effective-theory result by about 9% which increases to 22% in the pseudo-scalar case. Thus in this mass range the effect on the total cross section amounts to about 2% and 6%, respectively, which may be relevant in future precision studies.

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.

Light dark matter in NMSSM and implication on Higgs phenomenology

For the experimental search of neutralino dark matter, it is important to know its allowed mass and scattering cross section with the nucleon. In order to figure out how light a neutralino dark matter can be predicted in low energy supersymmetry, we scan over the parameter space of the NMSSM (next-to-minimal supersymmetric model), assuming all the relevant soft mass parameters to be below TeV scale. We find that in the parameter space allowed by current experiments the neutralino dark matter can be as light as a few GeV and its scattering rate off the nucleon can reach the sensitivity of XENON100 and CoGeNT. As a result, a sizable parameter space is excluded by the current XENON100 and CoGeNT data (the plausible CoGeNT dark matter signal can also be explained). The future 6000 kg-days exposure of XENON100 will further explore (but cannot completely cover) the remained parameter space. Moreover, we find that in such a light dark matter scenario a light CP-even or CP-odd Higgs boson must be present to satisfy the measured dark matter relic density. Consequently, the SM-like Higgs boson hSM may decay predominantly into a pair of light Higgs bosons or a pair of neutralinos so that the conventional decays like hSM→γγ is much suppressed.

Very lightCP-odd Higgs bosons of the NMSSM at the LHC in4b-quark final states

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 $\tan\beta$ 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.

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.

Light Higgs bosons in phenomenological NMSSM

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 neutral and charged Higgs boson searches is discussed.

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.