Searches for heavy Higgs bosons A/H decaying to ttbar are complicated by strong interference between the signal process and the irreducible background from SM ttbar production. These interference effects distort the signal shape from a Breit-Wigner peak to a peak-dip structure or even more complicated patterns and are not trivial to calculate or implement in MC simulations. ATLAS and CMS currently rely on different UFO implementations of A/H->ttbar production at LO and use different strategies to extract the interference patterns from the MadGraph predictions. It is crucial to compare the predictions obtained with the two approaches to ensure comparability of the ATLAS and CMS results.
Such a comparison is presented in this talk, along with a brief description of the latest cross-section calculations on which ATLAS BSM Higgs searches rely.
We analyze the potential sensitivity of the HL-LHC to BSM triple Higgs couplings in the framework of the 2HDM via hh production (where h is the Higgs at ~125 GeV). Depending on the parameter choice, the heavy CP-even Higgs can contribute in the s-channel, where the triple Higgs coupling la_hhH enters. We demonstrate which kind of effects arise, and how they depend on the mass, width and couplings of the heavy Higgs. We analyze the effects of experimental uncertainties, such as smearing and m_hh bin width.
The superweak extension adds an extra U(1) gauge symmetry to the standard model gauge group, and extends the field content by a complex scalar field and three generations of sterile neutrinos. There are six new, pheonmenologically important parameters: (i) the mass of the new gauge boson, (ii) an additional mixing angle in the neutral gauge sector, (iii) the mass of the new scalar, (iv) a scalar mixing angle, (v) the Higgs portal coupling and (vi) the mass of the heavy sterile neutrinos. We aim to perform a global scan of these parameters with respect to the electroweak precision observables and collider searches in the scalar sector. We argue that chi^2 values in the different search channels for scalars are essential to take collider limits into account properly in the global scan.
The trilinear Higgs coupling is an important quantity to investigate in order to determine the structure of the Higgs potential, and to probe possible effects of physics beyond the Standard Model (SM). Focusing on a scenario of the Two-Higgs-Doublet Model as a concrete example, I will discuss the calculation of the leading two-loop corrections to this coupling, and show that it can be significantly enhanced with respect to its SM prediction in certain regions of parameter space. Taking into account all relevant corrections up to the two-loop level, I will demonstrate that the current experimental bounds on the trilinear Higgs coupling already rule out significant parts of the parameter space that would otherwise be unconstrained. Finally, I will present a benchmark scenario illustrating the interpretation of the current results and future measurement prospects.
We present a reinterpretation study of existing results from the CMS Collaboration, specifically, searches for light Beyond the Standard Model (BSM) Higgs pairs produced in the chain decay ππβπ»SMβββ(ππ) into a variety of final states, in the context of the CP-conserving 2-Higgs Doublet Model (2HDM) Type-I. Through this, we test the Large Hadron Collider (LHC) sensitivity to a possible new signature, ππβπ»SMβππ΄βππβ, with ππβπππ+πβ and ββππΒ―. We perform a systematic scan over the 2HDM Type-I parameter space, by taking into account all available theoretical and experimental constraints, in order to find a region with a potentially visible signal. We investigate the significance of it through a full Monte Carlo simulation down to the parametrized detector level. We show that such a signal is an alternative promising channel to standard four-body searches for light BSM Higgses at the LHC already with an integrated luminosity of ξΈ=300 fbβ1. For a tenfold increase of the latter, discovery should be possible over most of the allowed parameter space.
The search of a high mass resonance decaying into WW in the dileptonic final state with CMS was performed for additional resonance masses up to 5000 GeV. These signals are assumed to have a non-zero width between 0.1% and 10% of the resonance mass. Thus, interference effects of the signal with the non-resonant WW background and the SM Higgs boson are also included. This presentation shows the effects of the signal widths and interference in detail.
The generic axion Effective Field Theory (EFT) Lagrangian has many free parameters, and leaves quite some freedom for the expected axion-like particle (ALP) phenomenology. In this work, we set up more constrained EFTs, to be used as benchmark scenarios to search for ALPs. Our guiding principle is to enforce true axion-like properties for the ALP. Indeed, though the Peccei-Quinn symmetry of the QCD axion is anomalous, it is so in specific ways, and this shows up as consistency conditions between the gauge boson and fermion couplings, which have to be enforced for generic axion EFTs. We will do so by classifying ALPs according to their two most common origins: DFSZ or KSVZ. The DFSZ computation will be simply recast from Two Higgs Doublet Model, whereas the KSVZ one is performed in a way so that no ambiguities arise due to the treatment of Ξ³5 in Dimensional Regularization.
The existence of charged Higgs bosons is a common prediction of the multiplet extension beyond the Standard Model (SM). With special consideration to the two Higgs doublet model (2HDM) and involving specific Yukawa Type-I, we address the phenomenology of charged Higgs boson collisions in both theoretically and experimentally feasible parameter space. In this context, we analyze a light charged Higgs boson and light scalar associated production, and check different final states. We prove that there is a large possibility that this spectacular signal could be found at the LHC when βs = 14 TeV and luminosity is 300 fbβ1.
The existence of additional Higgs bosons, besides the one discovered by the LHC (hereafter, denoted by Hobs ) already a decade ago, is predicted by most (if not all) frameworks of new physics. Observation of a second Higgs boson (charged or neutral) will thus provide firm evidence that the underlying manifestation of the Electroweak Symmetry Breaking (EWSB) mechanism is a non-minimal one. The majority of analyses, both phenomenological and experimental ones, involving additional Higgs bosons concentrate on QCD- induced production modes (like gluon fusion), However, these QCD induced it is not necessarily to be high in new physics models, owing to the non-standard couplings of the new Higgs bosons to the fermions and gauge bosons. The inclusive cross sections mediated by electroweak EW processes can dominate over the QCD induced process. As a reference we take the Type-I two Higgs doublet model (2HDM) as a simple extension of Standard Model to contain charged Higgs, pseudoscalar and additional CP even Higgs, where we have sizable parameter space where the EW process dominates over the QCD process. In this talk I would like to show a full detector-level Monte Carlo (MC) analysis to establish that the EW production can provide simultaneously visible signals of all the three additional Higgs bosons of the Type-I 2HDM at the LHC.
We show how the presence of Vector-Like Quarks (VLQs) with quantum numbers identical to the top-quark ones alongside a Type-II 2-Higgs Doublet Model (2HDM-II) (pseudo)scalar sector can remove the stringent constraint on the mass of the charged Higgs boson $H^\pm$ (of some 580 GeV) emerging in such a scenario from $B$ physics results. We prove this to be the case for two representations of such VLQs, both a singlet and a doublet one, wherein the the lowest allowed $m_{H^\pm}$ value can be 80 GeV. This is due to cancellations onsetting in $b\to s\gamma$ topologies between VLQ and $H^\pm$ contributions. Furthermore, in order to enable one to probe the regions of, as it were, this `2HDM-II+VLQ' parameter space where this mechanism is most effective, we present several results on production cross sections and decay rates involving a top-quark companion ($T$) with VLQ nature and the 2HDM-II Higgs bosons, chiefly the $H^\pm$ state, which can then guide the search for both extended Higgs and quark sectors at the Large Hadron Collider (LHC) at CERN. Specifically, we highlight the case of VLQ pair production $pp\to T\bar T$ followed by $T\to H^\pm b$ decays, where the $H^\pm$ state may in turn decay into $\tau\nu$ or $tb$ pairs, depending on whether $m_{H^\pm}< m_t$ or $m_{H^\pm}>m_t$, respectively.
We study the possibility that LHC searches for Vector-Like Quarks (VLQs) can profile the nature of the latter, i.e., whether they belong to a singlet, doublet or triplet representation, assuming that the Higgs structure of the underlying theoretical framework is of 2-Higgs Doublet Model (2HDM) type. In order to achieve this, we exploit both Standard Model (SM) decays of π VLQs, i.e., into π quarks and πΒ±,π,β bosons, and their exotic decays, i.e., into (new) π΅ fermions and π»Β±,π»,π΄ bosons. We show that quite specific decay patterns emerge in the different VLQ representations so that, depending upon which π decay patterns are accessed at the CERN machine, one may be able to ascertain the underlying Beyond Standard Model structure, especially so if mass knowledge of the new fermionic and bosonic sector can be inferred from (other) data.