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Register a new userProbing vector-like quark models with Higgs-boson pair production
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We investigate Higgs-boson pair production at the LHC when the final state system arises from decays of vector-like quarks coupling to the Higgs boson and the Standard Model quarks. Our phenomenological study includes next-to-leading-order QCD corrections, which are important to guarantee accurate predictions, and focuses on a detailed analysis of a di-Higgs signal in the four $b$-jet channel. Whereas existing Run II CMS and ATLAS analyses are not specifically designed for probing non-resonant, vector-like-quark induced, di-Higgs production, we show that they nevertheless offer some potential for these modes. We then investigate the possibility of distinguishing between the various di-Higgs production mechanisms by exploiting the kinematic properties of the signal.
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At the Large Hadron Collider, we prove the feasibility to detect pair production of the lightest CP-even Higgs boson $h$ of Type II 2-Higgs Doublet Models through $q q^{()}to q q^{()} {hh}$ (vector-boson fusion). We also show that, through the $hhto 4b$ decay channel in presence of heavy-flavour tagging, further exploiting forward/backward jet sampling, one has direct access to the $lambda_{Hhh}$ triple Higgs coupling -- which constrains the form of the Higgs potential.
The production of pairs of Higgs bosons at hadron colliders provides unique information on the Higgs sector and on the mechanism underlying electroweak symmetry breaking (EWSB). Most studies have concentrated on the gluon fusion production mode which has the largest cross section. However, despite its small production rate, the vector-boson fusion channel can also be relevant since even small modifications of the Higgs couplings to vector bosons induce a striking increase of the cross section as a function of the invariant mass of the Higgs boson pair. In this work, we exploit this unique signature to propose a strategy to extract the $hhVV$ quartic coupling and provide model-independent constraints on theories where EWSB is driven by new strong interactions. We take advantage of the higher signal yield of the $bbar b bbar b$ final state and make extensive use of jet substructure techniques to reconstruct signal events with a boosted topology, characteristic of large partonic energies, where each Higgs boson decays to a single collimated jet . Our results demonstrate that the $hhVV$ coupling can be measured with 45% (20%) precision at the LHC for $mathcal{L}=$ 300 (3000) fb$^{-1}$, while a 1% precision can be achieved at a 100 TeV collider.
A coupling of a scalar, charged under an unbroken global U(1) symmetry, to the Standard Model via the Higgs portal is one of the simplest gateways to a dark sector. Yet, for masses $m_{S}geq m_{H}/2$ there are few probes of such an interaction. In this note we evaluate the sensitivity to the Higgs portal coupling of di-Higgs boson production at the LHC as well as at a future high energy hadron collider, FCC-hh, taking into account the full momentum dependence of the process. This significantly impacts the sensitivity compared to estimates of changes in the Higgs-coupling based on the effective potential. We also compare our findings to precision single Higgs boson probes such as the cross section for vector boson associated Higgs production at a future lepton collider, e.g. FCC-ee, as well as searches for missing energy based signatures.
We present the calculation of the cross section and invariant mass distribution for Higgs boson pair production in gluon fusion at next-to-leading order (NLO) in QCD. Top-quark masses are fully taken into account throughout the calculation. The virtual two-loop amplitude has been generated using an extension of the program GoSam supplemented with an interface to Reduze for the integral reduction. The occurring integrals have been calculated numerically using the program SecDec. Our results, including the full top-quark mass dependence for the first time, allow us to assess the validity of various approximations proposed in the literature, which we also recalculate. We find substantial deviations between the NLO result and the different approximations, which emphasizes the importance of including the full top-quark mass dependence at NLO.
In this work we explore the sensitivity to the Higgs self-coupling $lambda$ in the production of two Higgs bosons via vector boson scattering at the LHC. Although these production channels, concretely $W^+W^- to HH$ and $ ZZ to HH$, have lower rates than gluon-gluon fusion, they benefit from being tree level processes, being independent of top physics and having very distinctive kinematics that allow to obtain very clean experimental signatures. This makes them competitive channels concerning the sensitivity to the Higgs self-coupling. In order to give predictions for the sensitivity to this coupling, we first study the role of $lambda$ at the subprocess level, both in and beyond the Standard Model, to move afterwards to the LHC scenario. We characterize the $ppto HHjj$ case first and then provide quantitative results for the values of $lambda$ that can be probed at the LHC in vector boson scattering processes after considering the Higgs boson decays. We focus mainly in $ppto bbar{b}bbar{b}jj$, since it has the largest signal rates, and also comment on the potential of other channels, such as $ppto bbar{b}gammagamma jj$, as they lead to cleaner, although smaller, signals. Our whole study is performed for a center of mass energy of $sqrt{s}=14$ TeV and for various future expected LHC luminosities.
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