Higgs Boson Pair Production Research Articles

Pseudoscalar Higgs boson pair production at a photon-photon collision in the two Higgs doublet model

In this study, the direct pair production of the pseudoscalar Higgs boson at a photon-photon collision is analyzed in the context of two Higgs doublet model, taking account the complete one-loop contributions. In order to illustrate the effect of the new physics, four benchmark points scenarios, which are consistent with theoretical and current experimental constraints, are chosen in the type-I of THDM with an exact alignment limit. In these benchmark points, the CP even lightest Higgs boson ($h^0$) have the Standard Model like couplings to the gauge bosons. The effect of individual contributions from each type of one-loop diagrams on the total cross section are examined in detail. The dependence of total cross section on the center-of-mass energy is also presented at the various polarization configurations of the incoming photons. Moreover, the regions $m_{12}^2-\tan\beta$ and $m_A-\tan\beta$ in the parameter space of the THDM are scanned for some fixed values of other parameters. The box-type diagrams make a much larger contribution to the total cross section than the others at high energies. Total cross section can be enhanced by a two factor thanks to opposite polarized photons as well as threshold effects.

Higgs physics at CMS

The most recent results of a Higgs boson production and properties from the CMS Collaboration using the LHC Run 1 and Run 2 data are reported. These include analyses of a Higgs boson decaying to a pair of photons, four leptons via Z boson pair decays and the associated production of a Higgs boson with top quark pair, predicted by the Standard Model (SM). The studies of a Higgs boson decays to a pair of bottom quarks, a pair of tau leptons and a charm quark pair are also presented. The Higgs boson production via vector boson fusion (VBF) and decaying to invisible particles is reported here as well. The analysis of a Higgs boson decay to a pair of muons is also presented. The study of a Higgs boson pair production at 13 TeV is performed as well and projections of a Higgs boson self couplings together with the couplings to other particles at the HL-LHC are made.

Possibility of observing Higgs bosons at the ILC in the lepton-specific 2HDM

The Higgs boson pair production at a linear $e^+e^-$ collider is analyzed in the $4\tau$ final state in the context of lepton-specific or type IV 2HDMs. Both beams are assumed to be unpolarized. The Higgs boson pairs (HA) are produced through off-shell $Z^*$ production and decay to $\tau$-jets which is the main decay channel for neutral Higgs bosons in type IV. Using a simplified detector simulation based on SiD detector at ILC, the 4$\tau$ signal is studied through the $\tau$-jet pair invariant mass reconstruction. Several benchmark scenarios are considered for center of mass energies of 500 and 1000 GeV at integrated luminosity of 500$fb^{-1}$. Among Standard Model (SM) background processes, the main background is $e^+e^- \to ZZ$ followed by $Z \to \tau\tau$. This background is however, well under control. With the luminosity assumed in the analysis, striking signals are obtained beyond the reach of LHC. Such signals would allow for precise determination of masses and cross sections and alredy much lower luminosities are sufficient for discovery.

Search for Higgs boson pair production in the gamma gamma WW^* channel using pp collision data recorded at sqrt{s}=13 TeV with the ATLAS detector

Searches for non-resonant and resonant Higgs boson pair production are performed in the gamma gamma WW^* channel with the final state of gamma gamma ell nu jj using 36.1 hbox {fb}^{-1} of proton–proton collision data recorded at a centre-of-mass energy of sqrt{s}=13 TeV by the ATLAS detector at the Large Hadron Collider. No significant deviation from the Standard Model prediction is observed. A 95% confidence-level observed upper limit of 7.7 pb is set on the cross section for non-resonant production, while the expected limit is 5.4 pb. A search for a narrow-width resonance X decaying to a pair of Standard Model Higgs bosons HH is performed with the same set of data, and the observed upper limits on sigma (pprightarrow X)times B(Xrightarrow HH) range between 40.0 and 6.1 pb for masses of the resonance between 260 and 500 GeV, while the expected limits range between 17.6 and 4.4 pb. When deriving the limits above, the Standard Model branching ratios of the H{rightarrow }{gamma gamma } and H{rightarrow }WW^* are assumed.

Fiducial distributions in Higgs and Drell-Yan production at N3LL+NNLO

The perturbative description of certain differential distributions across a wide kinematic range requires the matching of fixed-order perturbation theory with resummation of large logarithmic corrections to all orders. We present precise matched predictions for transverse-momentum distributions in Higgs boson (H) and Drell-Yan pair (DY) production as well as for the closely related ϕη* distribution at the LHC. The calculation is exclusive in the Born kinematics, and allows for arbitrary fiducial selection cuts on the decay products of the colour singlets, which is of primary relevance for experimental analyses. Our predictions feature very small residual scale uncertainties and display a good convergence of the perturbative series. A comparison of the predictions for DY observables to experimental data at 8 TeV shows a very good agreement within the quoted errors.

Search for Resonant and Nonresonant Higgs Boson Pair Production in the bb[over ¯]τ^{+}τ^{-} Decay Channel in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector.

A search for resonant and nonresonant pair production of Higgs bosons in the bb[over ¯]τ^{+}τ^{-} final state is presented. The search uses 36.1 fb^{-1} of pp collision data with sqrt[s]=13 TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. Decays of the τ-lepton pairs with at least one τ lepton decaying to final states with hadrons and a neutrino are considered. No significant excess above the expected background is observed in the data. The cross-section times branching ratio for nonresonant Higgs boson pair production is constrained to be less than 30.9fb, 12.7 times the standard model expectation, at 95%confidence level. The data are also analyzed to probe resonant Higgs boson pair production, constraining a model with an extended Higgs sector based on two doublets and a Randall-Sundrum bulk graviton model. Upper limits are placed on the resonant Higgs boson pair production cross-section times branching ratio, excluding resonances X in the mass range 305 GeV<m_{X}<402 GeV in the simplified hMSSM minimal supersymmetric model for tanβ=2 and excluding bulk Randall-Sundrum gravitons G_{KK} in the mass range 325 GeV<m_{G_{KK}}<885 GeV for k/M[over ¯]_{Pl}=1.

Search for Higgs boson pair production in the upgamma upgamma boverline{b} final state with 13 TeV pp collision data collected by the ATLAS experiment

A search is performed for resonant and non-resonant Higgs boson pair production in the upgamma upgamma boverline{b} final state. The data set used corresponds to an integrated luminosity of 36.1 fb−1 of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. No significant excess relative to the Standard Model expectation is observed. The observed limit on the non-resonant Higgs boson pair cross-section is 0.73 pb at 95% confidence level. This observed limit is equivalent to 22 times the predicted Standard Model cross-section. The Higgs boson self-coupling (κλ = λHHH/λHHHSM) is constrained at 95% confidence level to −8.2 < κλ < 13.2. For resonant Higgs boson pair production through Xto HHto upgamma upgamma boverline{b} , the limit is presented, using the narrow-width approximation, as a function of mX in the range 260 GeV < mX < 1000 GeV. The observed limits range from 1.1 pb to 0.12 pb over this mass range.

Two-loop massless QCD corrections to the g + g \u2192 H + H four-point amplitude

We compute the two-loop massless QCD corrections to the four-point amplitude g + g → H + H resulting from effective operator insertions that describe the interaction of a Higgs boson with gluons in the infinite top quark mass limit. This amplitude is an essential ingredient to the third-order QCD corrections to Higgs boson pair production. We have implemented our results in a numerical code that can be used for further phenomenological studies.

Higgs boson pair production in non-linear Effective Field Theory with full mt-dependence at NLO QCD

We present a calculation of the NLO QCD corrections to Higgs boson pair production within the framework of a non-linearly realised Effective Field Theory in the Higgs sector, described by the electroweak chiral Lagrangian. We analyse how the NLO corrections affect distributions in the Higgs boson pair invariant mass and the transverse momentum of one of the Higgs bosons. We find that these corrections lead to significant and non-homogeneous K-factors in certain regions of the parameter space. We also provide an analytical parametrisation for the total cross-section and the mhh distribution as a function of the anomalous Higgs couplings that includes NLO corrections. Such a parametrisation can be useful for phenomenological studies.

Soft gluon resummation for Higgs boson pair production including finite Mt effects

We perform the all orders resummation of threshold enhanced contributions for the Higgs boson pair production cross section via gluon fusion, including finite top quark mass (Mt) effects. We present results for the total cross section and Higgs pair invariant mass (Mhh) distribution. We obtain results at next-to-leading logarithmic accuracy (NLL) which retain the full Mt dependence, and are matched to the full next-to-leading order (NLO) prediction. Our NLL+NLO results represent the most advanced prediction with full Mt dependence for this process, and produce an increase of about 4% in the total cross section with respect to the NLO result for LHC energies, and for a central scale μ0 = Mhh/2. We also consistently combine the full NLL with the next-to-next-to-leading logarithmically (NNLL) accurate resummation computed in the Born-improved large-Mt limit, and match it to the next-to-next-to-leading order approximation of ref. [1], so called NNLOFTa. We find that the resummation effects are very small at NNLL for μ0 = Mhh/2, in particular below 1% at 13 TeV, indicating that the perturbative expansion is under control. In all cases the resummation effects are found to be substantially larger for the central scale μ0 = Mhh, resulting in a more stable cross section with respect to scale variations than the fixed order calculation.

Higgs boson pair production at future hadron colliders: From kinematics to dynamics

The measurement of the triple Higgs coupling is a key benchmark for the LHC and future colliders. It directly probes the Higgs potential and its fundamental properties in connection to new physics beyond the Standard Model. There exist two phase space regions with an enhanced sensitivity to the Higgs self-coupling, the Higgs pair production threshold and an intermediate top pair threshold. We show how the invariant mass distribution of the Higgs pair offers a systematic way to extract the Higgs self-coupling, focusing on the leading channel $pp\to hh+X\to b\bar b\ \gamma\gamma+X$. We utilize new features of the signal events at higher energies and estimate the potential of a high-energy upgrade of the LHC and a future hadron collider with realistic simulations. We find that the high-energy upgrade of the LHC to 27 TeV would reach a 5$\sigma$ observation with an integrated luminosity of 2.5 ab$^{-1}$. It would have the potential to reach 15% (30%) accuracy at the 68% (95%) confidence level to determine the SM Higgs boson self-coupling. A future 100 TeV collider could improve the self-coupling measurement to better than 5% (10%) at the 68% (95%) confidence level.

Future prospects of mass-degenerate Higgs bosons in the CP -conserving two-Higgs-doublet model

The scenario of two mass-degenerate Higgs bosons within the general two-Higgs-doublet model (2HDM) is revisited. We focus on the global picture when two $CP$-even Higgs bosons of $h$ and $H$ are nearly mass-degenerate. A global fit to the signal strength of the 125 GeV Higgs measured at the LHC is performed. Based on the best-fit result of the 2HDM mixing angles $(\alpha,\beta)$, theoretical constraints, charged and $CP$-odd Higgs boson direct search constraints and the electroweak precision constraints are imposed to the 2HDM parameter space. We present the signal predictions of the $(4b\,, 2b\,2\gamma)$ channels for the benchmark models at the LHC 14 TeV runs. We also study the direct Higgs boson pair productions at the LHC, and the Z-associated Higgs boson pair production search at the ILC 500 GeV runs, as well as the indirect probes at the CEPC 250 GeV run. We find that the mass-degenerate Higgs boson scenario in the Type-II 2HDM can be fully probed by these future experimental searches.

Analysis of b quark pair production signal from neutral 2HDM Higgs bosons at future linear colliders

In this paper, the b quark pair production events are analyzed as a source of neutral Higgs bosons of the two Higgs doublet model type I at linear colliders. The production mechanism is e^{+}e^{-} rightarrow Z^{(*)} rightarrow HA rightarrow b{bar{b}}b{bar{b}} assuming a fully hadronic final state. The analysis aim is to identify both CP-even and CP-odd Higgs bosons in different benchmark points accommodating moderate boson masses. Due to pair production of Higgs bosons, the analysis is most suitable for a linear collider operating at sqrt{s} = 1 TeV. Results show that in selected benchmark points, signal peaks are observable in the b-jet pair invariant mass distributions at integrated luminosity of 500 hbox {fb}^{-1}.

Pair production of Higgs boson in NMSSM at the LHC with the next-to-lightest CP-even Higgs boson being SM-like**Supported by National Natural Science Foundation of China (11705048)

The next-to-minimal supersymmetric standard model (NMSSM) more naturally accommodates a Higgs boson with a mass of approximately 125 GeV than the minimal supersymmetric standard model (MSSM). In this work, we assume that the next-to-lightest CP-even Higgs boson h2 is the SM-like Higgs boson h, whereas the lightest CP-even Higgs boson h1 is dominantly singlet-like. We discuss the h1h1, h2h2, and h1h2 pair production processes via gluon-gluon fusion at the LHC for an collision energy of 14 TeV, and we consider the cases in which one Higgs boson decays to and the other decays to γγ or τ+τ−. We find that, for mh1 ≲ 62 GeV, the cross section of the gg → h1h1 process is relatively large and maximally reaches 5400 fb, and the production rate of the final state can reach 1500 fb, which make the detection of this final state possible for future searches of an integrated luminosity of 300 and 3000 fb−1. This is mainly due to the contributions from the resonant production process pp → h2 → h1h1 and the relatively large branching ratio of and . The cross sections of the pp → h2h2 and pp → h1h2 production processes maximally reach 28 fb and 133 fb, respectively.

Higgs boson pair production at NNLO with top quark mass effects

We consider QCD radiative corrections to Higgs boson pair production through gluon fusion in proton collisions. We combine the exact next-to-leading order (NLO) contribution, which features two-loop virtual amplitudes with the full dependence on the top quark mass Mt, with the next-to-next-to-leading order (NNLO) corrections computed in the large-Mt approximation. The latter are improved with different reweighting techniques in order to account for finite-Mt effects beyond NLO. Our reference NNLO result is obtained by combining one-loop double-real corrections with full Mt dependence with suitably reweighted real-virtual and double-virtual contributions evaluated in the large-Mt approximation. We present predictions for inclusive cross sections in pp collisions at sqrt{s} = 13, 14, 27 and 100 TeV and we discuss their uncertainties due to missing Mt effects. Our approximated NNLO corrections increase the NLO result by an amount ranging from +12% at sqrt{s}=13 TeV to +7% at sqrt{s}=100 TeV, and the residual uncertainty of the inclusive cross section from missing Mt effects is estimated to be at the few percent level. Our calculation is fully differential in the Higgs boson pair and the associated jet activity: we also present predictions for various differential distributions at sqrt{s}=14 and 100 TeV, and discuss the size of the missing Mt effects, which can be larger, especially in the tails of certain observables. Our results represent the most advanced perturbative prediction available to date for this process.

Search strategies for pair production of heavy Higgs bosons decaying invisibly at the LHC

The search for heavy Higgs bosons at the LHC represents an intense experimental program, carried out by the ATLAS and CMS collaborations, which includes the hunt for invisible Higgs decays and dark matter candidates. No significant deviations from the SM backgrounds have been observed in any of these searches, imposing significant constraints on the parameter space of different new physics models with an extended Higgs sector. Here we discuss an alternative search strategy for heavy Higgs bosons decaying invisibly at the LHC, focusing on the pair production of a heavy scalar H together with a pseudoscalar A, through the production mode qq¯→Z⁎→HA. We identify as the most promising signal the final state made up of 4b+ETmiss, coming from the heavy scalar decay mode H→hh→bb¯bb¯, with h being the discovered SM-like Higgs boson with mh=125GeV, together with the invisible channel of the pseudoscalar. We work within the context of simplified MSSM scenarios that contain quite heavy sfermions of most types with O(10)TeV masses, while the stops are heavy enough to reproduce the 125 GeV mass for the lightest SM-like Higgs boson. By contrast, the gauginos/higgsinos and the heavy MSSM Higgs bosons have masses near the EW scale. Our search strategies, for a LHC center-of-mass energy of s=14TeV, allow us to obtain statistical significances of the signal over the SM backgrounds with values up to ∼1.6σ and ∼3σ, for total integrated luminosities of 300fb−1 and 1000fb−1, respectively.

Parton shower and NLO-matching uncertainties in Higgs boson pair production

We perform a detailed study of NLO parton shower matching uncertainties in Higgs boson pair production through gluon fusion at the LHC based on a generic and process independent implementation of NLO subtraction and parton shower matching schemes for loop-induced processes in the Sherpa event generator. We take into account the full top-quark mass dependence in the two-loop virtual corrections and compare the results to an effective theory approximation. In the full calculation, our findings suggest large parton shower matching uncertainties that are absent in the effective theory approximation. We observe large uncertainties even in regions of phase space where fixed-order calculations are theoretically well motivated and parton shower effects expected to be small. We compare our results to NLO matched parton shower simulations and analytic resummation results that are available in the literature.

Search for Higgs boson pair production in events with two bottom quarks and two tau leptons in proton–proton collisions at [formula omitted

A search for the production of Higgs boson pairs in proton–proton collisions at a centre-of-mass energy of 13TeV is presented, using a data sample corresponding to an integrated luminosity of 35.9fb−1 collected with the CMS detector at the LHC. Events with one Higgs boson decaying into two bottom quarks and the other decaying into two τ leptons are explored to investigate both resonant and nonresonant production mechanisms. The data are found to be consistent, within uncertainties, with the standard model background predictions. For resonant production, upper limits at the 95% confidence level are set on the production cross section for Higgs boson pairs as a function of the hypothesized resonance mass and are interpreted in the context of the minimal supersymmetric standard model. For nonresonant production, upper limits on the production cross section constrain the parameter space for anomalous Higgs boson couplings. The observed (expected) upper limit at 95% confidence level corresponds to about 30 (25) times the prediction of the standard model.

Double Higgs production at the 14 TeV LHC and a 100 TeV pp collider

We consider effective Higgs boson couplings, including both $CP$-even and $CP$-odd couplings, which affect Higgs boson pair production. Through partial wave analysis, we find that the process $gg\ensuremath{\rightarrow}hh$ is dominated by the $s$-wave component even at a 100 TeV $pp$ collider. Making use of $s$-wave kinematics, we propose a cut efficiency function to mimic the collider simulation and obtain the potential of measuring Higgs effective couplings at the 14 TeV LHC with an integrated luminosity of $3000\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ and at a 100 TeV $pp$ collider. Analytical expressions of 2\ensuremath{\sigma} exclusion limits at the LHC and $5\ensuremath{\sigma}$ discovery bands at the 100 TeV machine are given.

Universality of next-to-leading power threshold effects for colourless final states in hadronic collisions

We consider the production of an arbitrary number of colour-singlet particles near partonic threshold, and show that next-to-leading order cross sections for this class of processes have a simple universal form at next-to-leading power (NLP) in the energy of the emitted gluon radiation. Our analysis relies on a recently derived factorisation formula for NLP threshold effects at amplitude level, and therefore applies both if the leading-order process is tree-level and if it is loop-induced. It holds for differential distributions as well. The results can furthermore be seen as applications of recently derived next-to-soft theorems for gauge theory amplitudes. We use our universal expression to re-derive known results for the production of up to three Higgs bosons at NLO in the large top mass limit, and for the hadro-production of a pair of electroweak gauge bosons. Finally, we present new analytic results for Higgs boson pair production at NLO and NLP, with exact top-mass dependence.