The program HiggsBounds is a well-established tool for testing Beyond-the-Standard Model (BSM) theories with an extended Higgs sector against experimental limits from collider searches at LEP, Tevatron and LHC. Thus far, it could be applied to any neutral or charged Higgs bosons originating from the modified Higgs sector. Implicitly, these particles were assumed to exhibit a somewhat hierarchical Yukawa structure as present in the Standard Model, where in particular the couplings to first generation fermions could be neglected. In this work, we extend the HiggsBounds functionalities to go beyond these restrictions, thus making the code applicable to any neutral or charged BSM scalars. Moreover, we develop a new approach to implement experimental searches whose kinematic acceptance depends significantly on the values of the involved couplings. We achieve this by recasting the searches to general scalar models. Using this approach we incorporate relevant current experimental limits from LHC searches for exotic scalars, and present the implications of these limits for a dark matter scalar mediator model, a flipped Two-Higgs-Doublet Model and a supersymmetric model with R-parity violation.

Germany

Henning Bahl

Victor Lozano

Tim Stefaniak

Sweden

Jonas Wittbrodt

Testing exotic scalars with HiggsBounds

The presence of charged Higgs bosons is a generic prediction of multiplet extensions of the Standard Model (SM) Higgs sector. Focusing on the Two-Higgs-Doublet-Model (2HDM) with type I and lepton-specific Yukawa sectors, we discuss the charged Higgs boson collider phenomenology in the theoretically and experimentally viable parameter space. While almost all existing experimental searches at the LHC target the fermionic decays of charged Higgs bosons, we point out that the bosonic decay channels — especially the decay into a non-SM-like Higgs boson and a W boson — often dominate over the fermionic channels. Moreover, we revisit two genuine BSM effects on the properties of the discovered Higgs boson — the charged Higgs contribution to the diphoton rate and the Higgs decay to two light Higgs bosons — and their implication for the charged Higgs boson phenomenology. As main result of the present paper, we propose five two-dimensional benchmark scenarios with distinct phenomenological features in order to facilitate the design of dedicated LHC searches for charged Higgs bosons decaying into a W boson and a light, non-SM-like Higgs boson.

The forgotten channels: charged Higgs boson decays to a W ± and a non-SM-like Higgs boson

The program HiggsSignals confronts the predictions of models with arbitrary Higgs sectors with the available Higgs signal rate and mass measurements, resulting in a likelihood estimate. A new version of the program, HiggsSignals-2, is presented that contains various improvements in its functionality and applicability. In particular, the new features comprise improvements in the theoretical input framework and the handling of possible complexities of beyond-the-SM Higgs sectors, as well as the incorporation of experimental results in the form of simplified template cross section (STXS) measurements. The new functionalities are explained, and a thorough discussion of the possible statistical interpretations of the HiggsSignals results is provided. The performance of HiggsSignals is illustrated for some example analyses. In this context the importance of public information on certain experimental details like efficiencies and uncertainty correlations is pointed out. HiggsSignals is continuously updated to the latest experimental results and can be obtained at  https://gitlab.com/higgsbounds/higgssignals  .

Philip Bechtle

Spain

Sven Heinemeyer

Tobias Klingl

Georg Weiglein

HiggsSignals-2: probing new physics with precision Higgs measurements in the LHC 13 TeV era

We describe recent developments of the public computer code HiggsBounds. In particular, these include the incorporation of LHC Higgs search results from Run 2 at a center-of-mass energy of 13 TeV, and an updated and extended framework for the theoretical input that accounts for improved Higgs cross section and branching ratio predictions and new search channels. We furthermore discuss an improved method used in HiggsBounds to approximately reconstruct the exclusion likelihood for LHC searches for non-standard Higgs bosons decaying to  $$\tau \tau $$  <math> <mrow> <mi>τ</mi> <mi>τ</mi> </mrow> </math>   final states. We describe in detail the new and updated functionalities of the new version HiggsBounds-5.

Daniel Dercks

HiggsBounds-5: testing Higgs sectors in the LHC 13 TeV Era

The   <math> <mi>CP</mi> </math>  $$ \mathcal{CP} $$  structure of the Higgs boson in its coupling to the particles of the Standard Model is amongst the most important Higgs boson properties which have not yet been constrained with high precision. In this study, all relevant inclusive and differential Higgs boson measurements from the ATLAS and CMS experiments are used to constrain the   <math> <mi>CP</mi> </math>  $$ \mathcal{CP} $$ -nature of the top-Yukawa interaction. The model dependence of the constraints is studied by successively allowing for new physics contributions to the couplings of the Higgs boson to massive vector bosons, to photons, and to gluons. In the most general case, we find that the current data still permits a significant   <math> <mi>CP</mi> </math>  $$ \mathcal{CP} $$ -odd component in the top-Yukawa coupling. Furthermore, we explore the prospects to further constrain the   <math> <mi>CP</mi> </math>  $$ \mathcal{CP} $$  properties of this coupling with future LHC data by determining tH production rates independently from possible accompanying variations of the   <math> <mi>t</mi> <mover> <mi>t</mi> <mo>¯</mo> </mover> <mi>H</mi> </math>  $$ t\overline{t}H $$  rate. This is achieved via a careful selection of discriminating observables. At the HL-LHC, we find that evidence for tH production at the Standard Model rate can be achieved in the Higgs to diphoton decay channel alone.

Judith Katzy

Krisztian Peters

CERN

Matthias Saimpert

Indirect   <math> <mi>CP</mi> </math>  $$ \mathcal{CP} $$  probes of the Higgs-top-quark interaction: current LHC constraints and future opportunities

The prediction of additional Higgs bosons is one of the key features of physics beyond the Standard Model (SM) that gives rise to an extended Higgs sector. We assess the sensitivity of the Large Hadron Collider (LHC) in the high luminosity (HL) run alone and in combination with a possible future International Linear Collider (ILC) to probe heavy neutral Higgs bosons. We employ the Minimal Supersymmetric Standard Model (MSSM) as a framework and assume the light  $$\mathcal {CP}$$  <math> <mi>CP</mi> </math>  -even MSSM Higgs boson to be the Higgs boson observed at  $$125\,\mathrm{GeV}$$  <math> <mrow> <mn>125</mn> <mspace width="0.166667em"></mspace> <mi>GeV</mi> </mrow> </math>  . We discuss the constraints on the MSSM parameter space arising from the precision measurements of the rates of the detected signal at  $$125\,\mathrm{GeV}$$  <math> <mrow> <mn>125</mn> <mspace width="0.166667em"></mspace> <mi>GeV</mi> </mrow> </math>   and from direct searches for new heavy Higgs bosons in the  $$\tau ^+\tau ^-$$  <math> <mrow> <msup> <mi>τ</mi> <mo>+</mo> </msup> <msup> <mi>τ</mi> <mo>-</mo> </msup> </mrow> </math>  ,  $$b\bar{b}$$  <math> <mrow> <mi>b</mi> <mover> <mrow> <mi>b</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> </mrow> </math>   and di-Higgs (hh) final states. A new benchmark scenario for heavy Higgs searches in the  $$b\bar{b}$$  <math> <mrow> <mi>b</mi> <mover> <mrow> <mi>b</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> </mrow> </math>   channel is proposed in this context. For the future Higgs rate measurements at the HL-LHC and ILC two different scenarios are investigated, namely the case where the future rate measurements agree with the SM prediction and the case where the rates agree with the predictions of possible realizations of the MSSM Higgs sector in nature.

Stefan Liebler

HL-LHC and ILC sensitivities in the hunt for heavy Higgs bosons

We investigate the LHC phenomenology of a model where the Standard Model (SM) scalar sector is extended by two real scalar singlets. A $${{\mathbb {Z}}_2} \otimes {{\mathbb {Z}}_2} '$$ <math><mrow><msub><mi>Z</mi><mn>2</mn></msub><mo>⊗</mo><msup><mrow><msub><mi>Z</mi><mn>2</mn></msub></mrow><mo>′</mo></msup></mrow></math>  discrete symmetry is imposed to reduce the number of scalar potential parameters, which is spontaneously broken by the vacuum expectation values of the singlet fields. As a result, all three neutral scalar fields mix, leading to three neutral CP-even scalar bosons, out of which one is identified with the observed Higgs boson at 125 GeV. We explore all relevant collider signatures of the three scalars in this model. Besides the single production of a scalar boson decaying directly to SM particle final states, we extensively discuss the possibility of resonant multi-scalar production. The latter includes decays of the produced scalar boson to two identical scalars (“symmetric decays”), as well as to two different scalars (“asymmetric decays”). Furthermore, we discuss the possibility of successive decays to the lightest scalar states (“cascade decays”), which lead to experimentally spectacular three- and four-Higgs final states. We provide six benchmark scenarios for detailed experimental studies of these Higgs-to-Higgs decay signatures.

Croatia

Tania Robens

Two-real-scalar-singlet extension of the SM: LHC phenomenology and benchmark scenarios

We propose six new benchmark scenarios for Higgs boson searches in the Minimal Supersymmetric Standard Model. Our calculations follow the recommendations of the LHC Higgs Cross Section Working Group, and benefit from recent developments in the predictions for the Higgs-boson masses and mixing. All of the proposed scenarios are compatible with the most recent results from Run 2 of the LHC. In particular, they feature a scalar with mass and couplings compatible with those of the observed Higgs boson, and a significant portion of their parameter space is allowed by the limits from the searches for SUSY particles and additional Higgs bosons. We define a scenario where all SUSY particles are relatively heavy, and two scenarios with light colorless SUSY particles (charginos, neutralinos and, in one case, staus). In addition, we present two scenarios featuring alignment without decoupling, realized with either the lighter or the heavier scalar being SM-like, and a scenario with $$\mathcal {CP}$$ <math><mi>CP</mi></math>  violation.

Switzerland

Emanuele Bagnaschi

Israel

Elina Fuchs

Thomas Hahn

Shruti Patel

France

Pietro Slavich

United States

Carlos Wagner

MSSM Higgs boson searches at the LHC: benchmark scenarios for Run 2 and beyond

We propose two new benchmark scenarios for Higgs-boson searches in the Minimal Supersymmetric Standard Model (MSSM ). These scenarios are specifically designed for the low $$\tan \beta $$ <math><mrow><mo>tan</mo><mi>β</mi></mrow></math>  region. A light Higgs-boson mass prediction compatible with the observed value of $$125\,\hbox {GeV}$$ <math><mrow><mn>125</mn><mspace width="0.166667em"></mspace><mtext>GeV</mtext></mrow></math>  is ensured in almost the entire parameter space by employing a flexible supersymmetric (SUSY) mass scale, reaching values of up to $$10^{16}\,\hbox {GeV}$$ <math><mrow><msup><mn>10</mn><mn>16</mn></msup><mspace width="0.166667em"></mspace><mtext>GeV</mtext></mrow></math> . The MSSM Higgs-sector predictions are evaluated in an effective field theory (EFT ) framework that exhibits a Two-Higgs-Doublet-Model at the low scale. In the first scenario all SUSY particles are relatively heavy, whereas the second scenario features light neutralinos and charginos. Both scenarios are largely compatible with the most recent results from Run 2 of the LHC , and we highlight the main phenomenological features relevant for future LHC searches. In particular, we provide a detailed discussion of heavy Higgs-boson decays to neutralinos and charginos in the second scenario, and the arising collider signatures, in order to facilitate the design of dedicated LHC searches in the near future.

MSSM Higgs benchmark scenarios for Run 2 and beyond: the low $$\tan \beta $$ <math><mrow><mo>tan</mo><mi>β</mi></mrow></math>  region

In multi-Higgs models, the properties of one neutral scalar state approximate those of the Standard Model (SM) Higgs boson in a limit where the corresponding scalar field is roughly aligned in field space with the scalar doublet vacuum expectation value. In a scenario of alignment without decoupling, a SM-like Higgs boson can be accompanied by additional scalar states whose masses are of a similar order of magnitude. In the Minimal Supersymmetric Standard Model (MSSM), alignment without decoupling can be achieved due to an accidental cancellation of tree-level and radiative loop-level effects. In this paper we assess the impact of the leading two-loop O(αsht2) corrections on the Higgs alignment condition in the MSSM. These corrections are sizable and important in the relevant regions of parameter space and furthermore give rise to solutions of the alignment condition that are not present in the approximate one-loop description. We provide a comprehensive numerical comparison of the alignment condition obtained in the approximate one-loop and two-loop approximations, and discuss its implications for phenomenologically viable regions of the MSSM parameter space.

Howard E. Haber

The impact of two-loop effects on the scenario of MSSM Higgs alignment without decoupling