Higgs Pair Production Research Articles

Constraining the Higgs potential with neural simulation-based inference for di-Higgs production

Determining the form of the Higgs potential is one of the most exciting challenges of modern particle physics. Higgs pair production directly probes the Higgs self-coupling and should be observed in the near future at the High-Luminosity LHC. We explore how to improve the sensitivity to physics beyond the Standard Model through per-event kinematics for di-Higgs events. In particular, we employ machine learning through simulation-based inference to estimate per-event likelihood ratios and gauge potential sensitivity gains from including this kinematic information. In terms of the Standard Model Effective Field Theory, we find that adding a limited number of observables can help to remove degeneracies in Wilson coefficient likelihoods and significantly improve the experimental sensitivity. Published by the American Physical Society 2024

Single charged Higgs pair production in exclusive processes at the LHC

The production of a single charged Higgs boson pair by photon–photon interactions in pp collisions at the LHC is investigated in this exploratory study. We focus on the exclusive production, which is characterized by intact protons and two-rapidity gaps in the final state, and assume the type-I two-Higgs-doublet model, which still allows a light charged Higgs. Assuming the leptonic H±→[τντ]\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H^{\\pm }\\rightarrow [\ au \ u _{\ au }]$$\\end{document} decay mode, we derive predictions for the transverse momentum, rapidity and invariant mass distributions of the τ+τ-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au ^+ \ au ^-$$\\end{document} pair for different values of the charged Higgs mass. The contributions of different background processes are also estimated. Our results indicate that the contribution of the exclusive H+H-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H^+ H^-$$\\end{document} production for the [τ+ντ][τ-ντ]\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$[\ au ^{+}\ u _{\ au }][\ au ^{-} \ u _{\ au }]$$\\end{document} final state is non-negligible and can, in principle, be used to searching for a light charged Higgs.

Machine-learning performance on Higgs-pair production associated with dark matter at the LHC

Machine-learning performance on Higgs-pair production associated with dark matter at the LHC

Constraints on the trilinear and quartic Higgs couplings from triple Higgs production at the LHC and beyond

AbstractExperimental information on the trilinear Higgs boson self-coupling $$\kappa _3$$ κ 3 and the quartic self-coupling $$\kappa _4$$ κ 4 will be crucial for gaining insight into the shape of the Higgs potential and the nature of the electroweak phase transition. While Higgs pair production processes provide access to $$\kappa _3$$ κ 3 , triple Higgs production processes, despite their small cross sections, will provide valuable complementary information on $$\kappa _3$$ κ 3 and first experimental constraints on $$\kappa _4$$ κ 4 . We investigate triple Higgs boson production at the HL-LHC, employing efficient Graph Neural Network methodologies to maximise the statistical yield. We show that it will be possible to establish bounds on the variation of both couplings from the HL-LHC analyses that significantly go beyond the constraints from perturbative unitarity. We also discuss the prospects for the analysis of triple Higgs production at future high-energy lepton colliders operating at the TeV scale.

Prospects for exotic h→4τ decays in single and di-Higgs boson production at the LHC and future hadron colliders

We study the prospects for observing exotic decays of the Standard Model Higgs boson h into light beyond the Standard Model scalars a with mass ma≲mh/2 in the single Higgs and Higgs pair production channels at the high luminosity run of the Large Hadron Collider (HL-LHC). Discovery prospects for single Higgs production in the gluon-gluon fusion and vector boson fusion modes with the Higgs boson decaying via the exotic mode h→aa→4τ are analyzed at the HL-LHC. The projected sensitivity for exotic Higgs decays in the nonresonant Higgs pair production channel pp→hh→(h→bb¯)(h→aa→4τ)→2b4τ at the HL-LHC and a future s=100 TeV hadron collider (FCC-hh) are also estimated. Furthermore, we study HL-LHC’s potential reach for the Higgs-strahlung process in the 2b4τ channel, taking into account the contamination from nonresonant Higgs pair production. Finally, the potential reach for resonant Higgs pair production in the 2b4τ channel at the HL-LHC is also explored for several choices of {mH,ma}. Our studies suggest that significant improvements over existing bounds are achievable in several production channels, motivating new dedicated searches for h→aa→4τ at the HL-LHC and future colliders. Published by the American Physical Society 2024

BSM patterns in scalar-sector coupling modifiers

We consider what multiple Higgs interactions may yet reveal about the scalar sector. We estimate the sensitivity of a Feynman topology-templated analysis of weak boson fusion Higgs pair production at present and future colliders — where the signal is a function of the Higgs coupling modifiers κV, κ2V, and κλ. While measurements are statistically limited at the LHC, they are under general perturbative control at present and future colliders, departures from the SM expectation give rise to a significant future potential for BSM discrimination in κ2V. We explore the landscape of BSM models in the space of deviations in κV, κ2V, and κλ, highlighting models that have measurable order-of-magnitude enhancements in either κ2V or κλ, relative to their deviation in the single Higgs coupling κV.

Light-quark Yukawa couplings from off-shell Higgs production

Yukawa couplings of the first quark generation are notoriously difficult to constrain due to their small values within the Standard Model. Here we propose Higgs off-shell production, with the Higgs boson decaying to four leptons, as a probe of the up- and down-quark Yukawa couplings. Using kinematic discriminants similar to the ones employed in the Higgs width measurements we find that the down (up) Yukawa coupling can be constrained to a factor of 156 (260) times its Standard Model value at the high-luminosity LHC assuming only experimental systematic uncertainties. Off-shell Higgs production hence provides better sensitivity to the first-generation quark Yukawa couplings with respect to other probes such as Higgs+jet or Higgs pair production.

Full NLO QCD predictions for Higgs-pair production in the 2-Higgs-doublet model

After the discovery of the Higgs boson in 2012 at the CERN Large Hadron Collider (LHC), the study of its properties still leaves room for an extended Higgs sector with more than one Higgs boson. 2-Higgs doublet models (2HDMs) are well-motivated extensions of the Standard Model (SM) with five physical Higgs bosons: two CP-even states h and H, one CP-odd state A, and two charged states H^pm _{}. In this letter, we present the calculation of the full next-to-leading order (NLO) QCD corrections to hH and AA production at the LHC in the 2HDM at small values of the ratio of the vacuum expectation values, tan beta , including the exact top-mass dependence everywhere in the calculation. Using techniques applied in the NLO QCD SM Higgs pair production calculation, we present results for the total cross section as well as for the Higgs-pair-mass distribution at the LHC. We also provide the top-quark scale and scheme uncertainties which are found to be sizeable.

Testing type II seesaw leptogenesis at the LHC* *C. H. is supported by the Sun Yat-Sen University Science Foundation, and the Fundamental Research Funds for the Central Universities, Sun Yat-sen University (23qnpy58)

Type II seesaw leptogenesis simultaneously explains the origin of neutrino masses, the baryon asymmetry of our universe, and inflation. The Large Hadron Collider (LHC) provides an opportunity to directly test type II seesaw leptogenesis by looking for the predicted triplet Higgs. In this paper, we perform an analysis of the detection prospect for the triplet Higgs at the LHC through multi-electron channels. We find that due to the contribution of the process, the sensitivity of multi-electron channels searching for doubly-charged Higgs pair production can be improved. We also investigate the signals to probe production and find that the future high luminosity LHC could probe a triplet Higgs around 1.2 TeV at the level.

Charged Higgs induced 5 and 6 lepton signatures from heavy neutrinos at the LHC

We propose an anomaly free gauged U(1) extension of the SM where three right handed heavy neutrinos, being charged under the general U(1) gauge group, are introduced to explain the origin of the tiny neutrino mass through the seesaw mechanism after the general U(1) symmetry is broken. Due to the breaking of the general U(1) symmetry a neutral beyond the standard model gauge boson Z^prime acquires mass. There are two Higgs doublets in this model where one interacts with the SM fermions and the other one interacts with the right handed heavy neutrinos and charged leptons. The charged multiplet of the second Higgs can completely decay into the heavy neutrinos and charged lepton in the neutrinophilic limit of the model parameters. The charged Higgs pair production can be influenced due to presence of the Z^prime boson at the High Luminosity LHC (HL-LHC) in addition to the neutral SM gauge bosons. The pair produced charged Higgs bosons decay into SM charged leptons and heavy neutrinos. Following the leading decay modes of the heavy neutrinos into charged leptons and W boson we study the 5 and 6 lepton final states after the leptonic and hadronic decay of the W bosons considering solely muons and electrons in the final state. Combining the electron and muon final states we estimate the significance of the 5 and 6 charged lepton processes in the m_{H^pm }-m_N plane for different benchmark points of m_{Z^prime }. It is found that the 5 (6) charged lepton processes could be probed at the High Luminosity LHC (HL-LHC) with at least 5 (3) sigma significance and there are parameter regions where the significance could be larger.

Fast Columnar Physics Analyses of Terabyte-Scale LHC Data on a Cache-Aware Dask Cluster

The development of an LHC physics analysis involves numerous investigations that require the repeated processing of terabytes of data. Thus, a rapid completion of each of these analysis cycles is central to mastering the science project. We present a solution to efficiently handle and accelerate physics analyses on small-size institute clusters. Our solution uses three key concepts: vectorized processing of collision events, the “MapReduce” paradigm for scaling out on computing clusters, and efficiently utilized SSD caching to reduce latencies in IO operations. This work focuses on the latter key concept, its underlying mechanism, and its implementation. Using simulations from a Higgs pair production physics analysis as an example, we achieve an improvement factor of 6.3 in the runtime for reading all input data after one cycle and even an overall speedup of a factor of 14.9 after 10 cycles, reducing the runtime from hours to minutes.

Exclusive doubly charged Higgs boson pair production in pp collisions at the LHC

The type II seesaw model predicts the existence of a doubly charged Higgs boson ($H ^{\pm\pm}$), which can be produced through the Drell - Yan process and photon -- induced interactions at hadronic colliders. In recent years, such reactions have been largely investigated in inclusive processes, where both incident protons breakup and a large number of particles is produced in addition to the doubly charged Higgs pair. In this paper, we investigate, for the first time, the possibility of searching for $H ^{\pm\pm}$ in exclusive processes, which are characterized by two rapidity gaps and two intact very forward protons in final state. We estimate the associated cross section making use of the exclusive nature of the final state, together with the use of timing information provided by forward proton detectors. Moreover, the background is estimated considering distinct amounts of pile-up. Our results indicate that the exclusive doubly charged Higgs pair production is a promising way to search for signatures of the type II seesaw and to obtain lower mass bounds on $H ^{\pm\pm}$.

Machine learning the trilinear and light-quark Yukawa couplings from Higgs pair kinematic shapes

Revealing the Higgs pair production process is the next big challenge in high energy physics. In this work, we explore the use of interpretable machine learning and cooperative game theory for extraction of the trilinear Higgs self-coupling in Higgs pair production. In particular, we show how a topological decomposition of the gluon-gluon fusion Higgs pair production process can be used to simplify the machine learning analysis flow. Furthermore, we extend the analysis to include qoverline{q} → hh production, which is strongly suppressed in the Standard Model, to extract the trilinear Higgs coupling and to bound large deviations of the light-quark Yukawa couplings from the Standard Model values. The constraints on the rescaling of the trilinear Higgs self-coupling, κλ, and the rescaling of light-quark Yukawa couplings, κu and κd, at HL-LHC (FCC-hh) from single parameter fits are:κλ=0.531.70.971.03κu=−470430−5855κd=−360360−2628\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\displaystyle \\begin{array}{c}{\\kappa}_{\\lambda }=\\left[0.53,1.7\\right]\\ \\left(\\left[0.97,1.03\\right]\\right)\\\\ {}{\\kappa}_u=\\left[-470,430\\right]\\ \\left(\\left[-58,55\\right]\\right)\\\\ {}{\\kappa}_d=\\left[-360,360\\right]\\ \\left(\\left[-26,28\\right]\\right)\\end{array}} $$\\end{document}We show that the simultaneous modification of the Yukawa couplings can dilute the constraints on the trilinear coupling significantly. We perform similar analyses for FCC-hh. We discuss some motivated flavourful new physics scenarios where such an analysis prevails.

Top-Yukawa-induced corrections to Higgs pair production

Higgs-boson pair production at hadron colliders is dominantly mediated by the loop-induced gluon-fusion process gg → HH that is generated by heavy top loops within the Standard Model with a minor per-cent level contamination of bottom-loop contributions. The QCD corrections turn out to be large for this process. In this note, we derive the top-Yukawa-induced part of the electroweak corrections to this process and discuss their relation to an effective trilinear Higgs coupling with integrated out top-quark contributions.

Quartic Gauge-Higgs couplings: constraints and future directions

Constraints on quartic interactions of the Higgs boson with gauge bosons have been obtained by the experimental LHC collaborations focussing on the so-called κ framework of flat rescalings of SM-like interactions in weak boson fusion (WBF) Higgs pair production. While such approaches are admissible to obtain a qualitative picture of consistency with the SM when the statistical yield is low, once more statistics become available a more theoretically consistent framework of limit setting is desirable. Reviewing the constraints provided at the Large Hadron Collider, we first show that these limits are robust when considered in a leading order context. Turning to radiative corrections, we demonstrate the limitations of this approach in the SM, and by adopting Higgs effective field theory techniques, we clarify the sensitivity from single Higgs measurements to rescalings of quartic Higgs-gauge couplings. We then discuss avenues for sensitivity improvements of WBF analyses employing Graph Neural Networks to combat the large contributing backgrounds.

Laser-assisted CP-odd and CP-even Higgs bosons production in THDM

In this paper, we have theoretically studied the neutral Higgs pair production in Two Higgs Doublet Model (THDM) in the presence of a circularly polarized laser field. The laser-assisted differential partial cross section is derived in the centre of mass frame at the leading order including Z diagram. The total cross section is computed numerically by integrating the differential cross section over the solid angle . Two benchmark points are discussed for the THDM parameters. In the first step, we have analysed the total cross section of by considering H 0 as the standard model (SM)-like Higgs boson. Then, the process is studied by taking h 0 as the Higgs boson of the SM. For both benchmark points, the laser-assisted total cross section of the studied processes depends on the produced neutral Higgs masses, the centre of mass energy and the laser field parameters. In addition, the maximum cross section occurs at high centre of mass energy for the process as compared to that of .

Sensitivity to new physics in final states with multiple gauge and Higgs bosons

We analyse the sensitivity to beyond-the-Standard-Model effects of hadron-collider processes involving the interaction of two electroweak and two Higgs bosons, VVHH, with V being either a W or a Z boson. We examine current experimental results by the CMS collaboration in the context of a dimension-8 extension of the Standard Model in an effective-field-theory formalism. We show that constraints from vector-boson-fusion Higgs-pair production on operators that modify the Standard Model VVHH interactions are already comparable with or more stringent than those quoted in the analysis of vector-boson-scattering final states. We study the modifications of such constraints when introducing unitarity bounds, and investigate the potential of new experimental final states, such as ZHH associated production. Finally, we show perspectives for the high-luminosity phase of the LHC.

Benchmarking di-Higgs production in various extended Higgs sector models

We present a comprehensive study on Higgs pair production in various archetypical extended Higgs sectors such as the real and the complex 2-Higgs-Doublet Model, the 2-Higgs-Doublet Model augmented by a real singlet field and the Next-to-Minimal Supersymmetric extension of the Standard Model. We take into account all relevant theoretical and experimental constraints, in particular the experimental limits on non-resonant and resonant Higgs pair production. We present the allowed cross sections for Standard Model (SM)-like Higgs pair production and the ranges of the SM-like Yukawa and trilinear Higgs self-coupling that are still compatible with the applied constraints. Furthermore, we give results for the pair production of a SM-like with a non-SM-like Higgs boson and for the production of a pair of non-SM-like Higgs bosons. We find that di-Higgs production in the models under investigation can exceed the SM rate substantially, not only in the non-resonance region but also due to resonant enhancement. We give several benchmarks with interesting features such as large cross sections, the possibility to test CP violation, Higgs-to-Higgs cascade decays or di-Higgs production beating single Higgs production. In all of our benchmark points, the next-to-leading order QCD corrections are included in the large top-mass limit. For these points, we found that, depending on the model and the Higgs pair final state, the corrections increase the leading order cross section by a factor of 1.79 to 2.24. We also discuss the relation between the description of Higgs pair production in an effective field theory approach and in the specific models investigated here.

Two Higgs doublets, effective interactions and a strong first-order electroweak phase transition

It is well-known that type II two Higgs doublet models (2HDMs) can struggle to facilitate a strong first-order electroweak phase transition in the early universe whilst remaining theoretically appealing scenarios for many reasons. We analyse this apparent shortfall from the perspective of additional new physics. Starting from a consistent dimension-6 effective field theory Higgs potential extension, we identify the Higgs potential extensions that provide the necessary additional contributions required to achieve a strong first-order electroweak phase transition and trace their phenomenological implications for the Large Hadron Collider. In passing, we critically assess the reliability of the dimension-6 approximation depending on the expected 2HDM phenomenology. In particular, we focus on the role of Higgs pair production (resonant and non-resonant) and interference effects expected in top final states, which are the prime candidates of 2HDM exotics discoveries.

Enhanced Higgs pair production from higgsino decay at the HL-LHC

The scenario of multi-sector SUSY breaking predicts pseudo-goldstinos which are not absorbed by the gravitino and their mass can be as low as O(0.1) GeV. Since the interactions of pseudo-goldstinos are not so weak as gravitino, a produced higgsino can decay to a pseudo-goldstino plus a Higgs boson insider the detector at the LHC, and thus the higgsino pair production can lead to the signal of Higgs pair plus missing energy. For the scenario of natural SUSY which requires rather light higgsinos, such events may sizably outnumber the Higgs pair events predicted by the SM and be accessible at the HL-LHC (14 TeV with a luminosity of 3 ab−1). In this work we examine the observability of such Higgs pair plus missing energy from the decay of light higgsinos produced at the HL-LHC. Considering three channels of the Higgs-pair decay (bbWW⁎, bbγγ, bbbb), our detailed Monte Carlo simulations for the signal and backgrounds show that the best channel is bbbb+/ET, whose statistical significance can reach 2σ level for a light higgsino allowed by current experiments. This is over the SM Higgs pair result which is about 1.8σ.