Odd Higgs Boson Research Articles

Prospect and implications of cg→bH+→bAW+ production at the LHC

We study the prospect for discovering the $cg\ensuremath{\rightarrow}b{H}^{+}\ensuremath{\rightarrow}bA{W}^{+}$ process at the LHC. Induced by the top-flavor changing neutral Higgs coupling ${\ensuremath{\rho}}_{tc}$, the process may emerge if ${m}_{{H}^{+}}>{m}_{A}+{m}_{{W}^{+}}$, where ${H}^{+}$ and $A$ are charged and $CP$-odd Higgs bosons in the general two Higgs doublet model (g2HDM). We show that the $cg\ensuremath{\rightarrow}b{H}^{+}\ensuremath{\rightarrow}bA{W}^{+}$ process can be discovered at LHC run 3, while the full run 2 data at hand can constrain the parameter space significantly by searching for the same-sign dilepton final state. The process has unique implications on the hint of $gg\ensuremath{\rightarrow}A\ensuremath{\rightarrow}t\overline{t}$ excess at ${m}_{A}\ensuremath{\approx}400\text{ }\text{ }\mathrm{GeV}$ reported by CMS. When combined with other existing constraints, the $cg\ensuremath{\rightarrow}b{H}^{+}\ensuremath{\rightarrow}bA{W}^{+}$ process can essentially rule out the g2HDM explanation of such an excess.

Decayϕ→Zγγ(ϕ=h,H,A) in the minimal supersymmetric standard model

The decays of the CP-even ($h,\,H$) and the CP-odd ($A$) Higgs bosons $h,\,H,\,A\to Z\gamma\gamma$ are calculated in the context of the minimal supersymmetric standard model (MSSM), where they are induced at the one-loop level via box and reducible Feynman diagrams. For the numerical evaluation of the branching ratios we employ the decoupling limit and consider values for the MSSM parameters still consistent with the current experimental data. We consider a particular scenario for the radiative corrections to the Higgs boson masses, dubbed hMSSM, which leads to only two free parameters, namely $m_A$ and $\tan\beta$. We found that the branching ratio of the $CP$-odd Higgs boson decay $A\to Z\gamma\gamma$ can reach values up to $10^{-8}$ for $m_A=750$ GeV, which is three order of magnitude smaller than that of the $A\to\gamma\gamma$ channel. On the other hand, the branching ratio of the $H\to Z\gamma\gamma$ decay is of the order of $10^{-7}$ for large values of $m_H$ and small values of $\tan\beta$, which is comparable with the branching ratio of the $H\to Z\gamma$ channel. As far as the branching ratio of the SM-like Higgs boson decay $h\to Z\gamma\gamma$ is concerned, it is considerably suppressed, of the order of $10^{-11}$.

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}.

Phenomenology of 2HDM with vectorlike quarks

In this paper, we examine the consistency of the Large Hadron Collider (LHC) data collected during Runs 1 and 2 by the ATLAS and CMS experiments with the predictions of a 2-Higgs doublet model embedding vectorlike quarks (VLQs) for $pp\ensuremath{\rightarrow}H$, $A$ production and $H$, $A\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ decay mechanisms, respectively, of (nearly) degenerate $CP$-even ($H$) and $CP$-odd ($A$) Higgs bosons. We show that a scenario containing one single VLQ with electromagnetic charge $2/3$ can explain the above ATLAS and CMS data for masses in the region $350\text{ }\text{ }\mathrm{GeV}\ensuremath{\le}{m}_{\mathrm{VLQ}}\ensuremath{\le}1.5\text{ }\text{ }\mathrm{TeV}$ or so, depending on $\mathrm{tan}\ensuremath{\beta}$, and for several values of the mixing angle between the top quark ($t$) and its VLQ counterpart ($T$). We then perform a global fit onto the model by including all relevant experimental as well as theoretical constraints. The surviving samples of our analysis are discussed within $2\ensuremath{\sigma}$ of the LHC measurements. Additionally, we also comment on the recent anomalous result reported by CMS using Run 2 data on the associated Standard Model Higgs boson production with top quark pairs $pp\ensuremath{\rightarrow}t\overline{t}h$ with an observed significance of $3.3\ensuremath{\sigma}$. Other than these specific examples, we also present a phenomenological analysis of the main features of the model, including the most promising $T$ decay channels.

The light and heavy Higgs interpretation of the MSSM

We perform a parameter scan of the phenomenological Minimal Supersymmetric Standard Model (pMSSM) with eight parameters taking into account the experimental Higgs boson results from Run I of the LHC and further low-energy observables. We investigate various MSSM interpretations of the Higgs signal at 125,, mathrm {GeV}. First, we consider the case where the light mathcal{CP}-even Higgs boson of the MSSM is identified with the discovered Higgs boson. In this case it can impersonate the SM Higgs-like signal either in the decoupling limit, or in the limit of alignment without decoupling. In the latter case, the other states in the Higgs sector can also be light, offering good prospects for upcoming LHC searches and for searches at future colliders. Second, we demonstrate that the heavy mathcal{CP}-even Higgs boson is still a viable candidate to explain the Higgs signal – albeit only in a highly constrained parameter region, that will be probed by LHC searches for the mathcal{CP}-odd Higgs boson and the charged Higgs boson in the near future. As a guidance for such searches we provide new benchmark scenarios that can be employed to maximize the sensitivity of the experimental analysis to this interpretation.

Higgs boson mass constraint and theCPeven-CPodd Higgs boson mixing in an MSSM extension

One loop contributions to the CP even-CP odd Higgs boson mixings arising from contributions due to exchange of a vectorlike multiplet are computed under the Higgs boson mass constraint. The vectorlike multiplet consists of a fourth generation of quarks and a mirror generation. This sector brings in new CP phases which can be large consistent with EDM constraints. In this work we compute the contributions from the exchange of quarks and mirror quarks $t_{4L}, t_{4R}, T_{L}, T_{R}$, and their scalar partners, the squarks and the mirror squarks. The effect of their contributions to the Higgs boson masses and mixings are computed and analyzed. The possibility of measuring the effects of mixing of CP even and CP odd Higgs in experiment is discussed. It is shown that the branching ratios of the Higgs bosons into fermion pairs are sensitive to new physics and specifically to CP phases.

LHC searches for heavy neutral Higgs bosons with a top jet substructure analysis

We study the LHC searches for the heavy $CP$-odd Higgs boson $A$ and $CP$-even Higgs boson $H$ in the context of general two-Higgs-doublet model. Specifically, we consider the decay mode of $A/H\to t \bar t $ through the $b \bar b$ or $t \bar t $ associated production channels. In the so-called "alignment limit" of the two-Higgs-doublet model, this decay mode can be the most dominant one. By employing the HEPTopTagger and the multi-variable-analysis method, we present the search sensitivities for both $CP$-odd Higgs boson $A$ and $CP$-even Higgs boson $H$ via these channels at the high-luminosity LHC runs.

Neutral Higgs production at proton colliders in the CP-conserving NMSSM

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 both production processes we thus present accurate cross section predictions implemented in a new release of the code SusHi. We elaborate on the new features of an additional SU$(2)_L$ singlet in the production of CP-even and -odd Higgs bosons with respect to the MSSM and include a short discussion of theory uncertainties.

LHC searches for theCP-odd Higgs boson with a jet substructure analysis

The LHC searches for the CP-odd Higgs boson is studied (with masses from 300 GeV to 1 TeV) in the context of the general two-Higgs-doublet model. With the discovery of the 125 GeV Higgs boson at the LHC, we highlight one promising discovery channel of the hZ. This channel can become significant after the global signal fitting to the 125 GeV Higgs boson in the general two-Higgs-doublet model. It is particularly important in the scenario where two CP-even Higgs bosons in the two-Higgs-doublet model have the common mass of 125 GeV. Since the final states involve a Standard-Model-like Higgs boson, we apply the jet substructure analysis of the fat Higgs jet in order to eliminate the Standard Model background sufficiently. After performing the kinematic cuts, we present the LHC search sensitivities for the CP-odd Higgs boson with mass up to 1 TeV via this channel.

Constraints on parameter space from perturbative unitarity in models with three scalar doublets

We calculate an $s$-wave amplitude matrix for all the possible two-to-two body scalar boson elastic scatterings in models with three scalar doublets, including contributions from the longitudinal component of weak gauge bosons via the equivalence theorem approximation. Specifically, we concentrate on the two cases with two(one) active plus one(two) inert doublet fields, referred to as $\mathrm{I}(1+2)\mathrm{HDM}[\mathrm{I}(2+1)\mathrm{HDM}]$, under $CP$ conservation. We obtain three analytically irreducible submatrices with the $3\ifmmode\times\else\texttimes\fi{}3$ form and 18 eigenvalues for the amplitude matrix as an independent set, where the same formula can be applied to both models. By requiring a perturbative unitarity condition, we can constrain the magnitude of quartic coupling constants in the Higgs potential. This constraint, in particular in the $\mathrm{I}(1+2)\mathrm{HDM}$, can be translated into a bound on masses of extra active scalar bosons. Furthermore, when Standard Model-like Higgs boson couplings with weak gauge bosons are deviated from the Standard Model predictions, the unitarity condition provides an upper limit on the masses. We find that stronger upper bounds on the masses of the active $CP$-even and $CP$-odd Higgs bosons are obtained under the constraints from the unitarity and vacuum stability conditions, as well as the electroweak $S$, $T$ and $U$ parameters, as compared to those in two-Higgs doublet models with a softly broken ${Z}_{2}$ symmetry.

Phenomenological aspects of a TeV-scale alternative left-right model

We revisit the alternative left-right symmetric model, motivated by the superstring-inspired ${E}_{6}$ model. We systematically analyze the constraints imposed by theoretical and experimental bounds on the parameter space of this class of models. We perform a comprehensive analysis of the Higgs sector and show that three neutral $CP$-even and two $CP$-odd Higgs bosons in addition to two charged Higgs bosons can be light, of $\mathcal{O}(100)\text{ }\mathrm{GeV}$. We emphasize that the predictions of this model for the signal strengths of Higgs decays are consistent with the standard model expectations. We also explore discovery signatures of the exotic down-type quark, which is one of the salient predictions of this model.

Higgs bosons from top quark decays

In light of the discovery of a standard model (SM)-like Higgs boson ($h$) at the LHC, we investigate the top quark to Higgs boson transition $t\ensuremath{\rightarrow}{W}^{*}bh$, which is the leading $t\ensuremath{\rightarrow}h$ decay mode in the SM. We find the decay branching fraction to be $1.80\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}9}$. In comparison, the two-body, loop-induced $t\ensuremath{\rightarrow}ch$ transition occurs at $\ensuremath{\sim}1{0}^{\ensuremath{-}14}$ in the SM. We consider the consequences of gauge-invariant dimension-six operators affecting the $t\overline{t}h$ interaction and find that the decay branching fraction may be increased by a factor of 2 within current constraints on the coupling parameters from collider experiments. We also extend the calculation to the $CP$-conserving Type I and Type II two-Higgs-doublet models, including both $CP$-even and $CP$-odd Higgs bosons. For neutral scalar masses at about 100 GeV, the decay rates can be several times larger than the SM result in the allowed range of model parameters. Observation prospects at present and future colliders are briefly addressed.

Limits on neutral Higgs boson production in the forward region in pp collisions at $ \sqrt{s}=7 $ TeV

Abstract Limits on the cross-section times branching fraction for neutral Higgs bosons, produced in pp collisions at $ \sqrt{s}=7 $ TeV, and decaying to two tau leptons with pseudorapidities between 2.0 and 4.5, are presented. The result is based on a dataset, corresponding to an integrated luminosity of 1.0 fb−1, collected with the LHCb detector. Candidates are identified by reconstructing final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. A model independent upper limit at the 95% confidence level is set on a neutral Higgs boson cross-section times branching fraction. It varies from 8.6 pb for a Higgs boson mass of 90 GeV to 0.7 pb for a Higgs boson mass of 250 GeV, and is compared to the Standard Model expectation. An upper limit on tan β in the Minimal Supersymmetric Model is set in the $ m_{{{h^0}}}^{\max } $ scenario. It ranges from 34 for a CP -odd Higgs boson mass of 90 GeV to 70 for a pseudo-scalar Higgs boson mass of 140 GeV.

Confronting the MSSM and the NMSSM with the discovery of a signal in the two photon channel at the LHC

We confront the discovery of a boson decaying to two photons}, as reported recently by ATLAS and CMS, with the corresponding predictions in the Minimal Supersymmetric Standard Model (MSSM) and the Next-to-Minimal Supersymmetric Standard Model (NMSSM). We perform a scan over the relevant regions of parameter space in both models and evaluate the MSSM and NMSSM predictions for the dominant Higgs production channel and the photon photon decay channel. Taking into account the experimental constraints from previous direct searches, flavour physics, electroweak measurements as well as theoretical considerations, we find that a Higgs signal in the two photon channel with a rate equal to, or above, the SM prediction is viable over the full mass range $123\gev \lsim M_H \lsim 127\gev$, both in the MSSM and the NMSSM. We find that besides the interpretation of a possible signal at about $125\gev$ in terms of the lightest $\cp$-even Higgs boson, both the MSSM and the NMSSM permit also a viable interpretation where an observed state at about $125\gev$ would correspond to the second-lightest $\cp$-even Higgs boson in the spectrum, which would be accompanied by another light Higgs with suppressed couplings to $W$ and $Z$ bosons. We find that a significant enhancement of the $\ga\ga$ rate, compatible with the signal strenghts observed by ATLAS and CMS, is possible in both the MSSM and the NMSSM, and we analyse in detail different mechanisms in the two models that can give rise to such an enhancement. We briefly discuss also our predictions in the two models for the production and subsequent decay into two photons of a $\cp$-odd Higgs boson.

Search of Light New Physics at BABAR

In some extensions to the Standard Model such as the non-minimal symmetric model (nMSSM), a light CP -odd Higgs boson (A0) can arise, where light here means less than twice the mass of the B meson. The light Higgs boson can be produced via Υ (nS) → γA0, where n = 2, 3. BABAR has searched for evidence for the processes A0 → μ+μ−, A0 → τ+τ−, and, more recently, A0 → hadrons. First the BABAR experiment will be briefly described, then the results from searches of the (charged) leptonic decays of A0 will be highlighted. Afterward, the main result of the search for hadronic decays of the A0 will be presented in detail.

How to pin down theCPquantum numbers of a Higgs boson in itsτdecays at the LHC

We investigate how the $CP$ quantum numbers of a neutral Higgs boson or spin-zero resonance $\ensuremath{\Phi}$, produced at the CERN Large Hadron Collider, can be determined in its $\ensuremath{\tau}$-pair decay mode $\ensuremath{\Phi}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{\ensuremath{-}}{\ensuremath{\tau}}^{+}$. We use a method [S. Berge and W. Bernreuther, Phys. Lett. B 671, 470 (2009).] based on the distributions of two angles and apply it to the major 1-prong $\ensuremath{\tau}$ decays. We show for the resulting dilepton, lepton-pion, and two-pion final states that appropriate selection cuts significantly enhance the discriminating power of these observables. From our analysis we conclude that, provided a Higgs boson will be found at the LHC, it appears feasible to collect the event numbers needed to discriminate between a $CP$-even and -odd Higgs boson and/or between Higgs boson(s) with $CP$-conserving and $CP$-violating couplings after several years of high-luminosity runs.

Electroweak phase transitions in the secluded U(1)′-extended MSSM

The electroweak phase transition (EWPT) in the secluded-$U(1)'$-extended MSSM (sMSSM) is studied. Using the effective potential at zero and finite temperatures, we search for the non-MSSM-like EWPT in which the light stop mass is larger than the top quark mass. Scanning the parameters relevant to the EWPT, the upper limits of the Higgs boson masses, which are consistent with the strong first order EWPT, are derived. For the lightest CP-even and -odd Higgs bosons, we find $m_{H_1}<160$ GeV and $m_{A_1}<250$ GeV, respectively. In the sMSSM, the tree-level CP violation is possible by the complex soft supersymmetry breaking masses. It is observed that such a CP-violating effect does not spoil the strong first order EWPT for the typical parameter sets.

New constraints on a lightCP-odd Higgs boson and related NMSSM ideal Higgs scenarios

Recent BABAR limits on $\mathrm{BR}(\ensuremath{\Upsilon}(3S)\ensuremath{\rightarrow}\ensuremath{\gamma}a\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}})$ and $\mathrm{BR}(\ensuremath{\Upsilon}(3S)\ensuremath{\rightarrow}\ensuremath{\gamma}a\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})$ provide increased constraints on the $ab\overline{b}$ coupling of a $CP$-odd Higgs boson, $a$, with ${m}_{a}&lt;{M}_{\ensuremath{\Upsilon}(3S)}$. We extract these limits from the BABAR data and compare to the limits previously obtained using other data sets, especially the CLEO-III $\mathrm{BR}(\ensuremath{\Upsilon}(1S)\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}})$ 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) and yet can escape old LEP limits by virtue of decays to a pair of the lightest $CP$-odd Higgs bosons, ${h}_{1}\ensuremath{\rightarrow}{a}_{1}{a}_{1}$, with ${m}_{{a}_{1}}&lt;2{m}_{B}$. Most such scenarios with ${m}_{{a}_{1}}&lt;2{m}_{\ensuremath{\tau}}$ are eliminated, but the bulk of the ${m}_{{a}_{1}}&gt;7.5\text{ }\text{ }\mathrm{GeV}$ scenarios, which are theoretically the most favored, survive. We also outline the impact of the new ALEPH LEP results in the ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}Z+4\ensuremath{\tau}$ channel. For $\mathrm{tan}\ensuremath{\beta}\ensuremath{\ge}3$, only NMSSM ideal Higgs scenarios with ${m}_{{h}_{1}}\ensuremath{\gtrsim}98\text{ }\text{ }\mathrm{GeV}$ and ${m}_{{a}_{1}}$ close to $2{m}_{B}$ satisfy the ALEPH limits. For $\mathrm{tan}\ensuremath{\beta}\ensuremath{\lesssim}2$, the ALEPH limits are easily satisfied for the most theoretically preferred NMSSM scenarios, which are those with ${m}_{{a}_{1}}$ close to $2{m}_{B}$ and ${m}_{{h}_{1}}\ensuremath{\sim}90--100\text{ }\text{ }\mathrm{GeV}$.

Direct production of a lightCP-odd Higgs boson at the Tevatron and LHC

We show that the existing CDF $L=630\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ Tevatron data on $pp\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}X$ places substantial limits on a light $CP$-odd Higgs boson $a$ with ${m}_{a}&lt;2{m}_{B}$ produced via $gg\ensuremath{\rightarrow}a$, even for ${m}_{a}&gt;2{m}_{\ensuremath{\tau}}$ for which $\mathrm{BR}(a\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})$ is relatively small. Extrapolation of this existing CDF analysis to $L=10\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ suggests that Tevatron limits on the $ab\overline{b}$ coupling strength in the region ${m}_{a}&gt;8\text{ }\text{ }\mathrm{GeV}$ could be comparable to or better than limits from Upsilon decays in the ${m}_{a}&lt;7\text{ }\text{ }\mathrm{GeV}$ region. We also give rough estimates of future prospects at the LHC, demonstrating that early running will substantially improve limits on a light $a$ (or perhaps discover a signal). In particular, outside the Upsilon peak region, integrated luminosity of only $5\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}--20\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ (depending on ${m}_{a}$ and $\sqrt{s}$) could reveal a peak in ${M}_{{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}}$ and will certainly place important new limits on a light $a$. The importance of such limits in the context of next-to-minimal supersymmetric model Higgs discovery and $(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$ are outlined.

Bottomonium Spectroscopy with Mixing ofηbStates and a LightCP-Odd Higgs Boson

The mass of the ${\ensuremath{\eta}}_{b}(1S)$, measured recently by the BABAR Collaboration, is significantly lower than expected from QCD predictions for the $\ensuremath{\Upsilon}(1S)\mathrm{\text{\ensuremath{-}}}{\ensuremath{\eta}}_{b}(1S)$ hyperfine splitting. We suggest that the observed ${\ensuremath{\eta}}_{b}(1S)$ mass is shifted downwards due to a mixing with a $CP$-odd Higgs boson $A$ with a mass ${m}_{A}$ in the range 9.4--10.5 GeV compatible with LEP, CLEO, and BABAR constraints. We determine the resulting predictions for the spectrum of the ${\ensuremath{\eta}}_{b}(nS)\mathrm{\text{\ensuremath{-}}}A$ system and the branching ratios into ${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ as functions of ${m}_{A}$.