Besides supersymmetry, the other prime candidate of physics beyond the standard model (SM), crying out for verification at the CERN Large Hadron Collider (LHC), is extra-dimension. To hunt for effects of Kaluza-Klein (KK) excitations of known fermions and bosons is very much in the agenda of the LHC. These KK states arise when the SM particles penetrate in the extra space-like dimension(s). In this paper, we consider a 5d scenario, called `Universal Extra Dimension', where the extra space coordinate, compactified on an orbifold $S^1/Z_2$, is accessed by {\em all} the particles. The KK number ($n$) is conserved at all tree level vertices. This entails the production of KK states in pairs and renders the lightest KK particle stable, which leaves the detector carrying away missing energy. The splitting between different KK flavors is controlled by the zero mode masses and the bulk- and brane-induced one-loop radiative corrections. We concentrate on the production of an $n=1$ KK electroweak gauge boson in association with an $n=1$ KK quark. This leads to a signal consisting of {\em only one} jet, one or more leptons and missing $p_T$. For definiteness we usually choose the inverse radius of compactification to be $R^{-1} = 500$ GeV, which sets the scale of the lowest lying KK states. We show on a case-by-case basis (depending on the number of leptons in the final state) that with 10 ${\rm fb}^{-1}$ integrated luminosity at the LHC with $\sqrt{s}$ = 14 TeV this signal can be detected over the SM background by imposing appropriate kinematic cuts. We record some of the expectations for a possible intermediate LHC run at $\sqrt{s}$ = 10 TeV and also exhibit the integrated luminosity required to obtain a 5$σ$ signal as a function of $R^{-1}$.
The Standard Model (SM) Higgs boson, with its experimental discovery in 2012, has long been an interesting particle to study with the intention of exploring new physics ideas beyond the SM (BSM). Its properties are still not well understood, and there are several features in LHC Run 1 and Run 2 data which point at the possibility of extensions to the SM Higgs sector. This work explores the Madala hypothesis, which is the introduction of a heavy scalar (the Madala boson) to the SM, in addition to a real scalar $S$ and dark matter (DM) candidate $χ$. This hypothesis has previously been used to e…
The $HZγ$ coupling, which is highly sensitive to the new physics beyond the standard model, is studied through the process $pp\rightarrow pγp\rightarrow pHX$ at the LHC. To this purpose, an effective Lagrangian, in a model independent approach, with dimension six operators is considered in this paper. New interaction terms regarding beyond the standard model physics include the Higgs boson anomalous vertices in both CP-even and CP-odd structures. A detailed numerical analysis is performed to scrutinize the accurate constraints on the effective $HZγ$ couplings and to discuss how far the corresp…
We examine scenarios in the Next-to-Minimal Supersymmetric Standard Model (NMSSM), where pair-produced squarks and gluinos decay via two cascades, each ending in a stable neutralino as Lightest Supersymmetric Particle (LSP) and a Standard Model (SM)-like Higgs boson, with mass spectra such that the missing transverse energy, $E_{T}^{\text{miss}}$, is very small. Performing two-dimensional parameter scans and focusing on the hadronic $H\rightarrow b\bar{b}$ decay giving a $b\bar{b}b\bar{b} + E_{T}^{\text{miss}}$ final state we explore the sensitivity of a current LHC general-purpose jets+$E_{T}…
Current interpretations of the LHC results on two Higgs doublet models (2HDM) underestimate the sensitivity due to neglecting higher order effects. In this work, we revisit the impact of these effects using the current cross-section times branching ratio limits of the $A\to hZ, H \to VV$ and $H\to hh$ channels. With a degenerate heavy Higgs mass $m_Φ$, we find that the LHC searches gain sensitivity to the small $\tanβ$ region after including loop corrections, even close to $\cos(β-α)=0$ which is not reachable at tree level for all types of 2HDM. For a benchmark point with $m_Φ=300$ GeV, $\tanβ…
The Standard Model effective field theory (SMEFT) provides a general framework to include the dynamics of the beyond standard model physics residing at a certain higher energy scale $Λ$. We study the top-quark production along with a Higgs boson and a jet (tHq) at the LHC experiment within the framework of the SMEFT. First, identifying the relevant sensitive dimension-6 SMEFT operators, a strategy is developed to constrain the Wilson Coefficients (WC) corresponding to these associated SMEFT operators using the latest LHC measurements, providing a complementary way to the global-fit approach. T…
We demonstrate that measurements of the neutral-current Drell-Yan transverse momentum distribution binned in invariant mass are sensitive to unexplored dimension-8 parameters of the Standard Model Effective Field Theory (SMEFT). These distributions are sensitive to four-fermion operators with additional QCD field strength tensors. The determination of the Wilson coefficients of these operators provides a useful diagnostic tool that distinguishes possible ultraviolet completions of the SMEFT. We study how well these effects can be probed by current LHC data, and explore the sensitivity of the f…
We study the signatures of the triplet-quadruplet dark matter model at the LHC and future colliders, including the 100 TeV Super Proton-Proton Collider and the 240 GeV Circular Electron Positron Collider. The dark sector in this model contains one fermionic electroweak triplet and two fermionic quadruplets, which have two kinds of Yukawa couplings to the Higgs doublet. Electroweak production signals of the dark sector fermions in the $\text{monojet}+/\!\!\!\!E_\mathrm{T}$, disappearing track, and $\text{multilepton}+/\!\!\!\!E_\mathrm{T}$ channels at the LHC and the Super Proton-Proton Collide…
The addition of the QCD axion to the Minimal Supersymmetric Standard Model (MSSM) not only solves the strong CP problem but also modifies the dark sector with new dark matter candidates. While SUSY axion phenomenology is usually restricted to searches for the axion itself or searches for the ordinary SUSY particles, this work focuses on scenarios where the axion's superpartner, the axino, may be detectable at the Large Hadron Collider (LHC) in the decays of neutralinos displaced from the primary vertex. In particular, we focus on the KSVZ axino within the hadronic axion window. The decay lengt…
In this study of the Inert Doublet Model (IDM), we propose that the dijet + missing transverse energy channel at the Large Hadron Collider (LHC) will be an effective way of searching for the scalar particles of the IDM. This channel receives contributions from gauge boson fusion, and $t-$channel production, along with contributions from $H^+$ associated production. We perform the analysis including study of the Standard Model (SM) background with assumed systematic uncertainty, and optimise the selection criteria employing suitable cuts on the kinematic variables to maximise the signal signifi…
Higgs sectors extended by electroweakly charged scalars can be explored by scalar pair production at the LHC. We consider a fermiophobic scenario, with decays into a pair of gauge bosons, and a fermiophilic one, with decays into top and bottom quarks. After establishing the current bounds on simplified models, we focus on an SU(5)/SO(5) composite Higgs model. This first exploration demonstrates the need for dedicated searches at current and future colliders.
We establish the possibility of having a pseudo-Nambu-Goldstone boson (pNGB) Dark Matter (DM) candidate in the inspired Froggatt-Nielsen Singlet Model (iFNSM) wherein a direct connection exists between the DM mass and new flavon symmetry-breaking scale. We find a considerable allowed region of parameter space for the ensuing pseudoscalar DM, which is dependent upon the flavon Vacuum Expectation Value (VEV) and Yukawa couplings, over which it may be possible to explain the fermion mass hierarchy. Finally, we choose a Benchmark Point (BP) and perform detailed collider analyses to probe this DM s…
Searching for heavy vector bosons $Z^\prime$, predicted in models inspired by Grand Unification Theories, is among the challenging objectives of the LHC. The ATLAS and CMS collaborations have looked for $Z^\prime$ bosons assuming that they can decay only into Standard Model channels, and have set exclusion limits by investigating dilepton, dijet and to a smaller extent top-antitop final states. In this work we explore possible loopholes in these $Z^\prime$ searches by studying supersymmetric as well as leptophobic scenarios. We demonstrate the existence of realizations in which the $Z^\prime$ …
In the light of the 125 GeV Higgs ($h$) discovery at the Large Hadron Collider (LHC), one of the primary goals of the LHC and possible future colliders is to understand its interactions more precisely. Here we have studied the $h$-$b$-$\bar b$-$γ$ effective interaction terms arising out of gauge invariant dimension six operators in a model independent setting, as a potential source of new physics. Their role in some detectable final states have been compared with those coming from anomalous $h$-$b$-$\bar b$ interactions. We have considered the bounds coming from the existing collider and other…
In this letter, I propose a strategy to measure vector-boson scattering (VBS) at the LHCb experiment. The typical VBS topology at hadron colliders features two energetic back-to-back jets with large rapidities and two gauge bosons produced centrally. In this article, I show that such a topology can actually be probed by the LHCb detector. In particular, tagging only one of the two jets in combination with two same-sign leptons allows for a measurement with upcoming luminosities. I present an illustrative event selection where cross sections and differential distributions are computed for VBS a…
We present an analysis on the production of two same-sign lepton pairs at the LHC, mediated by bileptons in the $SU(3)_c\times SU(3)_L\times U(1)_X$ theory, the so-called 331 model. Compared to other 331 scenarios, in this model the embedding of the hypercharge is obtained with the addition of 3 exotic quarks and doubly-charged vector gauge bosons with lepton numbers $\pm 2$ in the spectrum ($Y^{\pm\pm}$), which can mediate the production of four-lepton final states. Furthermore, a complete description of the model requires the introduction of a Higgs scalar sector, which is a sextet of $SU(3)…
We investigate the possibility of detectable 2-Higgs Doublet Model (2HDM) type-II cross-sections at the High-Luminosity phase of the Large Hadron Collider (HL-LHC) for the production of the Standard Model (SM)-like Higgs boson ($h$) in association with a single top (anti)quark over the parameter space region corresponding to the so-called `wrong-sign solution' of the bottom (anti)quark Yukawa coupling. We isolate the latter by using the toolbox Magellan, which performs Markov Chain Monte Carlo (MCMC) scans in the presence of all current theoretical and experimental constraints, which relevance…
We study the prospect of determining the CP violating phase in $τ$-lepton Yukawa coupling at the Large Hadron Collider (LHC). While the current run is already exploring the production of a pair of the third generation $τ$ leptons from Higgs decay, these measurements are not sensitive enough to constrain the CP violating phase. In this paper, several CP odd observables are proposed and analyzed utilizing the dominant channels with the semi-invisible hadronic decay of $τ$. Several asymmetries corresponding to the T odd momentum correlations are also studied and their sensitivities to the CP viol…
The dilepton decay channels provide clean signatures and are an ideal hunting ground for high mass resonant, like Z', or non-resonant, like contact interactions or extra dimensions, searches at the LHC. The production of high invariant mass opposite sign lepton pairs in proton-proton collisions in the Standard Model is dominated by the Drell-Yan process. In addition to this photon or Z exchange mediated mechanism, photons radiated by the incoming protons can collide and produce lepton pairs. In this paper detailed calculations of the Drell-Yan process at next-to-next-to-leading order in QCD an…
We study the collider phenomenology of non minimal universal extra dimensional (nmUED) model in the context of the Large Hadron Collider at CERN. nmUED is an incarnation of the Standard Model in $(4+1)$ space-time dimensions compactified on an $\bf{S_1}/\bf{Z_2}$ orbifold supplemented with boundary localized operators with unknown coefficients. These coefficients parametrize the radiative corrections which are somehow arbitrary due to the lack of knowledge of the cut-off scale of such effective theory. It is possible to tune the masses and couplings of the Kaluza Klein (KK) excitations by tuni…
We study azimuthal asymmetries in diffractive J/$ψ$ production in ultraperipheral heavy-ion collisions at RHIC and LHC energies using the color glass condensate effective theory. Our calculation successfully describes azimuthal averaged $J/ψ$ production cross section measured by STAR and ALICE. We further predict very large $\cos 2ϕ$ and $\cos 4ϕ$ azimuthal asymmetries for diffractive $J/ψ$ production both in UPCs at RHIC and LHC energies and in eA collisions at EIC energy. These novel polarization dependent observables may provide complementary information for constraining gluon transverse sp…
We consider the prospects for measuring distinctive signatures of the CP-violating phases in the minimal supersymmetric extension of the Standard Model (MSSM) in light of the limits on sparticle masses from searches at the LHC. We use the CPsuperH code to evaluate model predictions and scan the parameter space using a geometric approach that maximizes CP-violating observables subject to the current upper limits on electric dipole moments (EDMs). We focus on the possible CP-violating asymmetry $A_{\rm CP}$ in $b \to s γ$ decay and on a possible CP-violating contribution to the $B_s - \overline{…
We revisit the multilepton ($ml$) + ${E\!\!\!\!/_T}$ + $X$ signatures of the Inert Doublet Model (IDM) of dark matter in future LHC experiments for $m =$ 3, 4 and simulate, for the first time, the $m = 5$ case. Here $X$ stands for any number of jets. We illustrate these signals with benchmark points consistent with the usual constraints like unitarity, perturbativity, the precision electroweak data, the observed dark matter relic density of the Universe and, most importantly, the stringent LHC constraints from the post Higgs ($h$) discovery era like the measured $M_h$ and the upper bound on th…
The Future Circular Collider (FCC-hh) is a proposed successor of the Large Hadron Collider (LHC). FCC-hh would push both the energy and intensity frontiers of searches for new physics particles. In particular, due to higher energy and luminosity than at the LHC, at FCC-hh there would be produced around $\simeq\!30$ times larger amount of $B$ mesons and $\simeq 120$ times of $W$ bosons, which then may decay into feebly interacting particles. In this paper we demonstrate the potential of FCC-hh by studying its sensitivity to heavy neutral leptons (HNLs) with masses $m_{N}<m_{B}$. We consider var…
We present sensitivity projections for discovering a heavy resonance decaying to electron and muon pairs and for probing the charged lepton non-universality in such decays at the HL-LHC and FCC-hh. The analysis takes into account the expected differences in the reconstruction efficiencies and the dilepton mass resolutions for dielectron and dimuon final states. We demonstrate how the analyses at HL-LHC naturally paves the way for a FCC-hh machine thereby underlining its importance.
Exploring the effects of $α$-clustered structure of $^{16}O$ nuclei in anisotropic flow fluctuations in $^{16}O$-$^{16}O$ collisions at the LHC within a CGC+Hydro framework
We present an extensive study of the MSSM parameter space allowing for general generation mixing in the squark sector. Employing an MCMC algorithm, we establish the parameter ranges which are allowed with respect to various experimental and theoretical constraints. Based on this analysis, we propose benchmark scenarios for future studies. Moreover, we discuss aspects of signatures at the LHC.
