Narrow Results

While the existence of a Higgs boson with a mass near 125 GeV has been clearly established, the detailed structure of the entire Higgs sector is yet unclear. Besides the Standard Model interpretation, various possibilities for extended Higgs sectors are being considered. The minimal supersymmetric extension (MSSM) features two Higgs doublets resulting in five physical Higgs bosons, which are subject to direct searches. Alternatively, more generic Two-Higgs Doublet models (2HDM) are used for the interpretation of results. The Next-to-Minimal Supersymmetric Model (NMSSM) has a more complex Higgs sector with seven physical states. Also exotic Higgs bosons decaying to invisible final states are considered. This article summarizes recent findings based on results from collider experiments.

The explanation of the small neutrino mass can be depicted using some handsome models like type-I and inverse seesaw where the Standard Model gauge singlet heavy right-handed neutrinos are deployed. The common thing in these two models is a lepton number violating parameter, however, its order of magnitude creates a striking difference between them making the nature of the right-handed heavy neutrinos a major play factor. In the type-I seesaw a large lepton number violating parameter involves the heavy right-handed neutrinos in the form of Majorana fermions while a small lepton number violating parameter being involved in the inverse seesaw demands the pseudo-Dirac nature of the heavy right-handed neutrinos. Such heavy neutrinos are accommodated in these models through the sizable mixings with the Standard Model light neutrinos. In this paper we consider the purely inverse seesaw scenario to study the pair production of the pseudo-Dirac heavy neutrinos followed by their various multilepton decay modes through the leading branching fraction at the leading order and next-to-leading order QCD at the LHC with a center-of-mass energy of 13 TeV and a luminosity of 3000 fb${}^{-1}$. We also consider a prospective 100 TeV hadron collider with luminosities of 3000 fb${}^{-1}$ and 30,000 fb${}^{-1}$, respectively to study the process. Using anomalous multilepton search performed by the CMS at the 8 TeV with 19.5 fb${}^{-1}$ luminosity we show prospective search reaches of the mixing angles for the three lepton and four lepton events at the 13 TeV LHC and 100 TeV hadron collider.

Many theories beyond the Standard Model (SM) predict new phenomena, such as $Z^{\prime }$ and vector-like quarks, in final states containing bottom- or top-quarks. It is challenging to reconstruct and identify the decay products and model the major background processes. Nevertheless, such final states offer great potential to reduce the SM backgrounds due to their characteristic decay signature. The latest searches in the third-generation quark final states using the full Run-2 proton–proton collision data collected by the ATLAS experiment are presented. Particularly, the recent results of di-bjet and top-antitop resonance searches and dark matter produced in association with a top-quark are discussed in these proceedings. The associated improvements in $b$-quark and top-quark identification techniques are also highlighted.

Quark flavor physics is the study of hadrons, their properties, and their decays into other particles. As a discipline, it simultaneously catalogues the nature of physical states within the Standard Model of particle physics, and in doing so tests the consistency and completeness of the Standard Model’s description of reality. Following the discovery of the Higgs field, it is more essential than ever to critically examine the Standard Model’s own coherence. Precision studies of quark flavor are one of the most sensitive experimental instruments for this task. I give a brief and necessarily selective overview of recent developments in quark flavor physics and discuss prospects for the next generation of experiments and facilities, with an emphasis on the energy scales of beyond Standard Model physics probed by these types of measurements.

In this paper, we explore the usage of boosted as well as semi-boosted topologies in all-hadronic $t\bar{t}$ final states in simulated $pp$ collisions at $\sqrt{s}=14$TeV, with top quarks decaying into a boosted hadronic top-jet or a W-jet and an isolated b-jet. Correlations between selected kinematic variables and their shapes are studied for scalar and vector resonances decaying to a pair of top quarks, and also for a models of $t\bar{t}$-associated production with an invisible dark matter particle pair. Stacked signal$+$background samples have been investigated in terms of the ability to resolve an excess of events over the Standard Model background in terms of the $t\bar{t}$ invariant mass, top quark transverse momentum and other 1D and 2D spectra using a parameterized detector simulation. A 2D extension of the BumpHunter algorithm is proposed, resulting in an improved signal sensitivity in specific 2D areas. We identify the most promising variables with the largest signal significance and smaller sensitivity to experimental uncertainties related to the jet energy calibration. We compare to statistical tests computing the background-only hypothesis compatibility and a likelihood fit of the signal strength.

In this paper, we explore the parameter space for processes with fermionic flavor violation within the Two Higgs Doublets Model (2HDM) type III, processes of Flavor Changing Neutral Currents (FCNCs) are present at Leading Order (LO) as dynamics beyond the Standard Model (SM) are included. We analyze the possible Yukawa couplings beyond the SM involving the quark top, as the experimental signatures would be a clear signal to conclude about the model. The processes we analyzed are same sign top pair production at the $pp$ collisions, and single top quark production in $ep$ collisions, through Deep Inelastic Scattering (DIS). To examine the scenarios that could exhibit such exotic events, we perform a scan in the parameter space to determine the observation possibilities for FCNC. We show the results considering the model parameters, coming from modified Yukawa interactions, $|{\tilde{\chi }}_{ij}^f|$ of the order one. In addition, we explore the order of magnitude of possible single top production via $\mu p$, at the proposed muon–proton collider. We found scattering values for these exotic processes of up to $\mathcal{𝒪}(10^{-2})pb$.