A search for resonances produced in 13 TeV proton-proton collisions and decaying into top-quark pairs is described. In this talk events where the top-quark decay produces a single isolated charged lepton, missing transverse momentum and jet activity compatible with a hadronic top-quark decay recorded with the ATLAS detector at the Large Hadron Collider are considered. We investigate the...
The large increase of pileup is one of the main experimental challenges for the High Luminosity-Large Hadron Collider (HL-LHC) physics program. HL-LHC is expected to start in 2027 and to provide an integrated luminosity of 3000fb-1 in ten years, a factor 10 more than what will be collected by 2023. A powerful new way to address this challenge is to exploit the time spread of the interactions...
The ATLAS and CMS experiments have an ambitious search program for charged Higgs bosons. The two main searches for $H^\pm$ at the LHC have traditionally been performed in the $\tau \nu$ and $t b$ decay channels, as they provide the opportunity to probe complementary regions of the Minimal SuperSymmetric Model (MSSM) parameter space. Charged Higgs bosons may decay also to light quarks, $H^\pm...
In this work, 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...
Many theories beyond the standard model predict new phenomena which decay to pairs of $W$ and $Z$ bosons. This talk summarizes results for these resonances in semileptonic final states in which one boson decays leptonically and the other boson decays hadronically, using full Run 2 data-sets collected with the ATLAS detector at the LHC between 2015 and 2018 at a center of mass energy of...
Hidden sector or dark sector states appear in many extensions to the Standard Model (SM), to provide particle mediators for dark matter in the universe. A new probe of this hypothetical hidden or dark sector may have become available at the energy frontier opened up by the LHC with the Higgs boson and its distinct couplings to SM particles. A search is conducted for a beyond-the-Standard-...
A variety of astrophysical observations showed direct evidence for the existence of dark matter which accounts for about 85\% of matter in the universe and does not interact with ordinary matter, except through gravity. Despite its abundance, dark matter particles are very elusive and hard to spot and no experiment confirmed their existence.
Many studies are in hunt for these elusive dark...
The Vector Boson Scattering (VBS) process of massive vector bosons is predicted by the Standard Model (SM) as being sensitive to ElectroWeak Symmetry Breaking (EWSB). Prior to EWSB, all vector bosons are massless and have transverse polarization states. However, after EWSB, $W$ and $Z$ bosons become massive and gain an extra polarization state - the longitudinal polarization, whereas photons...
