Searches For Additional Higgs Bosons Research Articles

Impact of new experimental data on the C2HDM: the strong interdependence between LHC Higgs data and the electron EDM

The complex two-Higgs doublet model (C2HDM) is one of the simplest extensions of the Standard Model with a source of CP-violation in the scalar sector. It has a \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathbb{Z}}_{2}$$\\end{document} symmetry, softly broken by a complex coefficient. There are four ways to implement this symmetry in the fermion sector, leading to models known as Type-I, Type-II, Lepton-Specific and Flipped. In the latter three models, there is a priori the surprising possibility that the 125 GeV Higgs boson couples mostly as a scalar to top quarks, while it couples mostly as a pseudoscalar to bottom quarks. This “maximal” scenario was still possible with the data available in 2017. Since then, there have been more data on the 125 GeV Higgs boson, direct searches for CP-violation in angular correlations of τ-leptons produced in Higgs boson decays, new results on the electron electric dipole moment, new constraints from LHC searches for additional Higgs bosons and new results on b → sγ transitions. Highlighting the crucial importance of the physics results of LHC’s Run 2, we combine all these experiments and show that the “maximal” scenario is now excluded in all models. Still, one can have a pseudoscalar component in \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$h\ au \\overline{\ au }$$\\end{document} couplings in the Lepton-Specific case as large as 87% of the scalar component for all mass orderings of the neutral scalar bosons.

H-COUP Version 3: A program for one-loop corrected decays of any Higgs bosons in non-minimal Higgs models

The H-COUP program is provided as a package of Fortran codes, which can compute observables related to Higgs bosons including radiative corrections in various extended Higgs sectors. We give a manual for the latest version of H-COUP (H-COUP_3.0), in which decay rates and branching ratios of all the Higgs bosons can be calculated at one-loop level in EW and Higgs interactions with QCD corrections in the Higgs singlet model, four types of the two Higgs doublet model with a softly-broken Z2 symmetry, and the inert doublet model. The previous version (H-COUP_2.0) can evaluate those only for the standard model like Higgs boson with the mass of 125 GeV (h). In H-COUP_3.0, renormalized quantities are computed based on the gauge-independent on-shell renormalization scheme. The source code of H-COUP_3.0 can be downloaded via the following link: http://www-het.phys.sci.osaka-u.ac.jp/~hcoup. By using H-COUP_3.0, we can compare the precise measurements of the properties of h and direct searches for additional Higgs bosons with their predictions at one-loop level, by which we can reconstruct the structure of the Higgs sector. New version program summaryProgram Title: H-COUP Version 3 5CPC Library link to program files:https://doi.org/10.17632/f88szmrj5x.3Developer's repository link:http://www-het.phys.sci.osaka-u.ac.jp/~hcoupLicensing provisions: GPLv3Programming language: Fortran90Journal reference of previous version: Comput. Phys. Commum. 257 (2020) 107512Does the new version supersede the previous version?: YesReasons for the new version: The previous version (H-COUP version 2) is a package of Fortran codes to provide one-loop corrected couplings, decay rates and branching ratios of the 125 GeV Higgs boson in the Higgs Singlet Model (HSM), the Two Higgs doublet models (THDMs) with a softly-broken Z2 symmetry, and the Inert Doublet Model (IDM). In the new version (H-COUP version 3), the H-COUP program has been improved to calculate the decay rates and the branching ratios of all the Higgs bosons including one-loop corrections in the above models. These calculations are performed based on the gauge independent on-shell renormalization scheme.Summary of revisions: We have added radiatively corrected decay rates and branching ratios for all the additional Higgs bosons, not only for the 125 GeV Higgs boson, in the extended Higgs models. Furthermore, several choices are provided for renormalization schemes used to evaluate electroweak corrections. The scalar two-point functions are renormalized by on-shell scheme as in the previous version, while the renormalization for the tadpole is performed by either the standard tadpole scheme or the alternative tadpole scheme. The users can choose these renormalization schemes.Nature of problem: Decay rates and branching ratios of all the Higgs bosons can be calculated with one-loop electroweak corrections and QCD corrections in the HSM, four types of the THDMs with the softly-broken Z2 symmetry, and the IDM. In the calculations of additional Higgs boson decays, for the three-body decay processes and loop induce processes of additional Higgs bosons, electroweak corrections are not included. As for the QCD correction, next-to-leading order or next-to-next-to-leading order corrections are included, depending on the decay process.Solution method: Electroweak corrections are evaluated based on the gauge independent on-shell renormalization scheme, while some parameters are renormalized by the MS‾ scheme. QCD corrections are evaluated with the MS‾ scheme.Additional comments including restrictions and unusual features: All functions up to the previous version are included in H-COUP version 3.

Searches for additional Higgs bosons and for vector leptoquarks in ττ final states in proton-proton collisions at sqrt{s} = 13 TeV

Three searches are presented for signatures of physics beyond the standard model (SM) in ττ final states in proton-proton collisions at the LHC, using a data sample collected with the CMS detector at sqrt{s} = 13 TeV, corresponding to an integrated luminosity of 138 fb−1. Upper limits at 95% confidence level (CL) are set on the products of the branching fraction for the decay into τ leptons and the cross sections for the production of a new boson ϕ, in addition to the H(125) boson, via gluon fusion (ggϕ) or in association with b quarks, ranging from mathcal{O} (10 pb) for a mass of 60 GeV to 0.3 fb for a mass of 3.5 TeV each. The data reveal two excesses for ggϕ production with local p-values equivalent to about three standard deviations at mϕ = 0.1 and 1.2 TeV. In a search for t-channel exchange of a vector leptoquark U1, 95% CL upper limits are set on the dimensionless U1 leptoquark coupling to quarks and τ leptons ranging from 1 for a mass of 1 TeV to 6 for a mass of 5 TeV, depending on the scenario. In the interpretations of the {M}_{textrm{h}}^{125} and {M}_{textrm{h},textrm{EFT}}^{125} minimal supersymmetric SM benchmark scenarios, additional Higgs bosons with masses below 350 GeV are excluded at 95% CL.

Simplified models for resonant neutral scalar production with missing transverse energy final states

Additional Higgs bosons appear in many extensions of the Standard Model (SM). While most existing searches for additional Higgs bosons concentrate on final states consisting of SM particles, final states containing beyond the SM (BSM) particles play an important role in many BSM models. In order to facilitate future searches for such final states, we develop a simplified model framework for heavy Higgs boson decays to a massive SM boson as well as one or more invisible particles. Allowing one kind of BSM mediator in each decay chain, we classify the possible decay topologies for each final state, taking into account all different possibilities for the spin of the mediator and the invisible particles. Our comparison of the kinematic distributions for each possible model realization reveals that the distributions corresponding to the different simplified model topologies are only mildly affected by the different spin hypotheses, while there is significant sensitivity for distinguishing between the different decay topologies. As a consequence, we point out that expressing the results of experimental searches in terms of the proposed simplified model topologies will allow one to constrain wide classes of different BSM models. The application of the proposed simplified model framework is explicitly demonstrated for the example of a mono-Higgs search. For each of the simplified models that are proposed in this paper we provide all necessary ingredients for performing Monte-Carlo simulations such that they can readily be applied in experimental analyses.

Possible indications for new Higgs bosons in the reach of the LHC: N2HDM and NMSSM interpretations

In several searches for additional Higgs bosons at the LHC, in particular in a CMS search exploring decays to pairs of top quarks, tbar{t}, and in an ATLAS search studying tau leptons, tau ^+tau ^-, local excesses of about 3,sigma standard deviations or above have been observed at a mass scale of approximately 400 ,text {GeV}. We investigate to what extent a possible signal in these channels could be accommodated in the Next-to-Two-Higgs-Doublet Model (N2HDM) or the Next-to Minimal Supersymmetric Standard Model (NMSSM). In a second step we analyze whether such a model could be compatible with both a signal at around 400,text {GeV} and 96,text {GeV}, where the latter possibility is motivated by observed excesses in searches for the b bar{b} final state at LEP and the di-photon final state at CMS. The analysis for the N2HDM reveals that the observed excesses at 400 ,text {GeV} in the tbar{t} and tau ^+tau ^- channels point towards different regions of the parameter space, while one such excess and an additional Higgs boson at around 96,text {GeV} could simultaneously be accommodated. In the context of the NMSSM an experimental confirmation of a signal in the tbar{t} final state would favour the alignment-without-decoupling limit of the model, where the Higgs boson at 125,text {GeV} could be essentially indistinguishable from the Higgs boson of the standard model. In contrast, a signal in the tau ^+tau ^- channel can only be accommodated outside of this limit, and parts of the investigated parameter space could be probed with Higgs signal-rate measurements at the (HL-)LHC.

Probing extended Higgs sectors by the synergy between direct searches at the LHC and precision tests at future lepton colliders

We discuss a possibility that the parameter space of the two Higgs doublet model is significantly narrowed down by considering the synergy between direct searches for additional Higgs bosons at the LHC and its luminosity upgraded operation and precision measurements of the Higgs boson properties at future electron-positron colliders such as the International Linear Collider. We show that, in the case where the coupling constants of the discovered Higgs boson are slightly different from the predicted values in the standard model, most of the parameter space is explored by the direct searches of extra Higgs bosons, in particular for the decays of the extra Higgs bosons into the discovered Higgs boson, and also by the theoretical arguments such as perturbative unitarity and vacuum stability. This can be done because there appears an upper limit on the mass of the extra Higgs bosons as long as the deviation exists in the Higgs boson coupling. We also show that in the alignment limit where all the Higgs boson couplings take the standard model like values most of the parameter space cannot be excluded because most of the Higgs to Higgs decays are suppressed and also there is no upper limit on the masses from the theoretical arguments.

MunuSSM: A python package for the [formula omitted]-from-[formula omitted] Supersymmetric Standard Model

We present the public python package munuSSM that can be used for phenomenological studies in the context of the μ-from-ν Supersymmetric Standard Model (μνSSM). The code incorporates the radiative corrections to the neutral scalar potential at full one-loop level. Sizable higher-order corrections, required for an accurate prediction of the SM-like Higgs-boson mass, can be consistently included via an automated link to the public code FeynHiggs. In addition, a calculation of effective couplings and branching ratios of the neutral and charged Higgs bosons is implemented. This provides the required ingredients to check a benchmark point against collider constraints from searches for additional Higgs bosons via an interface to the public code HiggsBounds. At the same time, the signal rates of the SM-like Higgs boson can be tested applying the experimental results implemented in the public code HiggsSignals. The python package is constructed in a flexible and modular way, such that it provides a simple framework that can be extended by the user with further calculations of observables and constraints on the model parameters. Program summaryProgram title: munuSSMCPC Library link to program files:https://doi.org/10.17632/s7r25zcpcy.1Developer’s repository link:https://gitlab.com/thomas.biekoetter/munussmLicensing provisions: GPLv3Programming language: Fortran, PythonNature of problem: We present a programme to analyse the Higgs sector of an extension of the Standard Model (SM) called the μ-from-ν Supersymmetric Standard Model (μνSSM). Based on the precise theoretical prediction of the scalar spectrum and the couplings of the Higgs bosons, the goal is to confront the model with experimental constraints. The programme provides an easy-to-use framework to compute further model predictions by making use of the already existing implementation.Solution method: The radiative corrections to the neutral scalar masses are calculated at full one-loop level. For an accurate prediction of the SM-like Higgs boson, sizable higher-order corrections are included in an approximate form. The calculation of cross sections and branching ratios to SM particles is implemented by rescaling the SM predictions with effective coupling coefficients. Exotic decays of the Higgs bosons are computed at tree level. Based on these ingredients, a parameter point can be checked against constraints from collider experiments.

Extended Scalar Sectors

Extended scalar sectors appear in various extensions of the Standard Model of particle physics, such as supersymmetric models. They are also generic extensions of the Standard Model and can address a number of its shortcomings. Direct searches for additional Higgs bosons and measurements of the 125-GeV Higgs boson, both of which provide insights into the different possible sectors, are carried out at the LHC. This review gives an overview of searches for the additional Higgs bosons and their implications for different models. The discussed analyses comprise searches for neutral and charged Higgs bosons that decay in various final states. In addition, the review summarizes the constraints from precision measurements, including in particular the observed couplings of the 125-GeV Higgs boson. While several models naturally incorporate a Higgs boson with couplings that are similar to the ones in the Standard Model, the measurements of the 125-GeV Higgs boson provide constraints on all considered extensions.

Associated production of Higgs boson with a photon at electron-positron colliders

A complete one-loop prediction for the single production of the neutral Higgs bosons in association with a photon in electron-positron collisions is presented in the framework the minimal supersymmetric standard model (MSSM), paying special attention to the individual contribution from each type of diagram. This process has no amplitude at tree level and is hence directly sensitive to one-loop impacts and the underlying dynamics of Higgs. To investigate the effect of the new physics, four different scenarios, which include a Higgs boson with mass and couplings consistent with those of the discovered Higgs boson and a considerable part of parameter space allowed by the bounds from the searches for additional Higgs bosons and sparticles, are chosen in the MSSM. The dependence of the cross section in both the standard model(SM) and MSSM on the center-of-mass energy is examined by considering the polarizations of the initial electron and positron beams. The effect of individual contributions from each type of one-loop diagram on the total cross section is also investigated in detail. Furthermore, the total cross sections of $e^- e^+ \rightarrow \gamma h^0$ as well as $e^- e^+ \rightarrow \gamma A^0$ are scanned over the plane $m_A-\tan\beta$ for each scenario. The full one-loop contributions are crucial for the analysis of beyond the SM physics at a future electron-positron collider.

Searches for additional Higgs bosons decaying to tau leptons at the LHC

The searches for additional Higgs bosons decaying to tau leptons in scenarios beyond the standard model will be summarised, from the pp collision data collected by the ATLAS and CMS experiments at LHC Run-2.

Phenomenology of the inflation-inspired NMSSM at the electroweak scale

The concept of Higgs inflation can be elegantly incorporated in the Next-to-Minimal Supersymmetric Standard Model (NMSSM). A linear combination of the two Higgs-doublet fields plays the role of the inflaton which is non-minimally coupled to gravity. This non-minimal coupling appears in the low-energy effective superpotential and changes the phenomenology at the electroweak scale. While the field content of the inflation-inspired model is the same as in the NMSSM, there is another contribution to the mu term in addition to the vacuum expectation value of the singlet. We explore this extended parameter space and point out scenarios with phenomenological differences compared to the pure NMSSM. A special focus is set on the electroweak vacuum stability and the parameter dependence of the Higgs and neutralino sectors. We highlight regions which yield a SM-like 125,hbox {GeV} Higgs boson compatible with the experimental observations and are in accordance with the limits from searches for additional Higgs bosons. Finally, we study the impact of the non-minimal coupling to gravity on the Higgs mixing and in turn on the decays of the Higgs bosons in this model.

Searches for additional Higgs bosons at CMS

Description of a broad range of analyses about additional Higgs bosons in the contest of Beyond Standard Model (BSM) physics performed at the CMS experiment at LHC.

Searching for additional Higgs bosons via Higgs cascades

The discovery of a 125 GeV Higgs boson at the Large Hadron Collider strongly motivates direct searches for additional Higgs bosons. In a type I two Higgs doublet model there is a large region of parameter space at $\tan\beta > 5$ that is currently unconstrained experimentally. We show that the process $gg \to H \to A Z \to ZZh$ can probe this region, and can be the discovery mode for an extended Higgs sector at the LHC. We analyze 9 promising decay modes for the $ZZh$ state, and we find that the most sensitive final states are $\ell\ell\ell\ell bb$, $\ell\ell jjbb$, $\ell\ell\nu\nu\gamma\gamma$ and $\ell\ell\ell\ell +{}$missing energy.

Impact of mathcal {CP}-violating interference effects on MSSM Higgs searches

Interference and mixing effects between neutral Higgs bosons in the MSSM with complex parameters are shown to have a significant impact on the interpretation of LHC searches for additional Higgs bosons. Complex MSSM parameters introduce mixing between the mathcal {CP}-even and mathcal {CP}-odd Higgs states h, H, A into the mass eigenstates h_1, h_2, h_3 and generate mathcal {CP}-violating interference terms. Both effects are enhanced in the case of almost degenerate states. Employing as an example an extension of a frequently used benchmark scenario by a non-zero phase phi _{A_t}, the interference contributions are obtained for the production of neutral Higgs bosons in gluon-fusion and in association with b-quarks followed by the decay into a pair of tau -leptons. While the resonant mixing increases the individual cross sections for the two heavy Higgs bosons h_2 and h_3, strongly destructive interference effects between the contributions involving h_2 and h_3 leave a considerable parameter region unexcluded that would appear to be ruled out if the interference effects were neglected.

Extracting the mass scale of a second Higgs boson from a deviation in h(125) couplings

We investigate the correlation between a possible deviation in the discovered Higgs boson h(125) couplings from the Standard Model prediction and the mass scale (M2nd) of the next-to-lightest Higgs boson in models with non-minimal Higgs sectors. In particular, we comprehensively study a class of next-to-minimal Higgs sectors which satisfy the electroweak ρ parameter to be one at tree level. We derive an upper limit on M2nd by imposing bounds from perturbative unitarity, vacuum stability, triviality and electroweak precision data as functions of the deviation in the hV V (V = W, Z) couplings. Furthermore, we discuss the complementarity between these bounds and the current LHC data, e.g., by considering direct searches for additional Higgs bosons and indirect constraints arising from the measured h(125) signal strengths.

Higgs Physics at CMS

The discovery of the Standard Model Higgs boson performed by the CMS and ATLAS collaborations during the LHC Run 1 has been an important success. This document is a short review of the search for the Higgs boson performed by the CMS collaboration during the LHC Run 1 and Run 2. In the first part, after a brief description of the Higgs boson production and decay channels, the Run-1 results are presented emphasizing the possible hints of New Physics. The main part of this document is devoted to the search for the Higgs boson with the 13-TeV data collected by the CMS experiment in 2015 and 2016, including the Standard Model searches as well as the Beyond Standard Model searches, such as the search for additional Higgs bosons and for resonant and non-resonant double Higgs boson production.

Charged Higgs Boson production at $$e^+e^-$$ e + e - colliders in the complex MSSM: a full one-loop analysis

For the search for additional Higgs bosons in the Minimal Supersymmetric Standard Model (MSSM) as well as for future precision analyses in the Higgs sector precise knowledge of their production properties is mandatory. We evaluate the cross sections for the charged Higgs boson production at e+e- colliders in the MSSM with complex parameters (cMSSM). The evaluation is based on a full one-loop calculation of the production mechanism e+e- -> H+H- and e+e- -> H^\pm W^\mp, including soft and hard QED radiation. The dependence of the Higgs boson production cross sections on the relevant cMSSM parameters is analyzed numerically. We find sizable contributions to many cross sections. They are, depending on the production channel, roughly of 5-10% of the tree-level results, but can go up to 20% or higher. The full one-loop contributions are important for a future linear e+e- collider such as the ILC or CLIC.

Higgs physics at CMS

This article reviews recent measurements of the properties of the standard model (SM) Higgs boson using data recorded with the CMS detector at the LHC: its mass, width and couplings to other SM particles. We also summarise highlights from searches for new physical phenomena in the Higgs sector as they are proposed in many extensions of the SM: flavour violating and invisible decay modes, resonances decaying into Higgs bosons and searches for additional Higgs bosons.

Neutral Higgs boson production at $$e^+e^-$$ e + e - colliders in the complex MSSM: a full one-loop analysis

For the search for additional Higgs bosons in the Minimal Supersymmetric Standard Model (MSSM) as well as for future precision analyses in the Higgs sector a precise knowledge of their production properties is mandatory. We evaluate the cross sections for the neutral Higgs boson production at e^+e^- colliders in the MSSM with complex parameters (cMSSM). The evaluation is based on a full one-loop calculation of the production channels e^+e^- -> h_i Z, h_i gamma, h_i h_j (i,j = 1,2,3), including soft and hard QED radiation. The dependence of the Higgs boson production cross sections on the relevant cMSSM parameters is analyzed numerically. We find sizable contributions to many cross sections. They are, depending on the production channel, roughly of 10-20% of the tree-level results, but can go up to 50% or higher. The full one-loop contributions are important for a future linear e^+e^- collider such as the ILC or CLIC. There are plans to implement the evaluation of the Higgs boson production cross sections into the code FeynHiggs.

Searches for additional Higgs bosons in multi-top-quarks events at the LHC and the International Linear Collider

We study direct searches of additional Higgs bosons in multi-top-quarks events at the LHC Run-II, its luminosity upgraded version with 3000 fb−1, and the International Linear Collider (ILC) with the collision energy of 1 TeV. Additional Higgs bosons are predicted in all kinds of extended Higgs sectors, and their detection at collider experiments is a clear signature of the physics beyond the standard model. We consider two Higgs doublet models with the discrete symmetry as benchmark models. If these additional Higgs bosons are heavy enough, the decay modes including top quarks can be dominant, and the searches in multi-top-quarks events become an important probe of the Higgs sector. We evaluate the discovery reach in the parameter space of the model, and find that there are parameter regions where the searches at the LHC with 3000 fb−1 cannot survey, but the searches at the ILC 1 TeV run can. The combination of direct searches at the LHC and the ILC is useful to explore extended Higgs sectors.