In this paper, we report a study of $Z$ boson kinematic distributions in the $Z$+ 1-jet events from proton-proton ($pp$) collisions at $\sqrt{s}$ = 13.6 TeV at the Large Hadron Collider (LHC) using Leading-Order (LO) event generators. Three LO event generators, namely Pythia8, Herwig7 and Sherpa2, are explored with the implementation of appropriate Parton Shower (PS) and Matrix Element (ME) corrections. The $Z$ boson is reconstructed from oppositely charged di-lepton pairs ($μ^+μ^-$ and $e^+e^-$), and the associate leading jet is reconstructed with the anti-$k_T$ algorithm with radius $r$=0.4. The di-lepton invariant mass, $M_{\ell^+\ell^-}$, and the transverse momentum of the reconstructed $Z$ boson, $p_{T}^Z$, distributions are extensively studied by comparing three of the Monte Carlo (MC) predictions. In addition to this, we also explore several other kinematic distributions associated with the candidate lepton and the jet to distinguish the modelling of the LO event generators in depth. Furthermore, various showering modules within these event generators are explored for $Z$ + 1-jet production. While the three of these MC frameworks reproduce the $Z$ + 1-jet kinematics similarly, certain discrepancies in their predictions are identified in some variables. We analyzed them using different statistical tests. The best match of the $p_{T}^Z$ spectra was found between the Pythia8 and Sherpa2 results.
Analysis of the charged multiplicity in proton-proton inelastic interactions at the LHC energies in the setting of Dual Parton Model is presented. Data from the CMS experiment and the data simulated at different energies in various pseudo-rapidity windows using the event generator PYTHIA8are analysed and compared with the calculations from the model. Each inelastic scattering is assumed to follow the Poisson distribution. The theoretical Koba-Nielsen-Olesen (KNO) scaling of the multiplicity distributions is studied and compared with previously published experimental results at $\sqrt{s}$ = 0.9…
Discussions are underway for a high-energy proton-proton collider. Two preliminary ideas are the $\sqrt{s}=33$ TeV HE-LHC and the $\sqrt{s}=100$ TeV VLHC. With Bayesian statistics, we calculate the probabilities that the LHC, HE-LHC and VLHC discover SUSY in the future, assuming that nature is described by the CMSSM and given the experimental data from the LHC, LUX and Planck. We find that the LHC with $300$/fb at $\sqrt{s}=14$ TeV has a $15$-$75%$ probability of discovering SUSY. Should that run fail to discover SUSY, the probability of discovering SUSY with $3000$/fb is merely $1$-$10%$. Wer…
The Higgs boson $H$ has the largest coupling to the top quark $t$ among the standard model (SM) fermions. This is one of the ideal places to investigate new physics beyond SM. In this work, we study the potential of determining Higgs boson $CP$ properties at the LHC and future 33 TeV and 100 TeV $pp$ colliders by analysing various operators formed from final states variables in $t\bar{t}H$ production. The discrimination power from SM coupling is obtained with Higgs boson reconstructed from $ H\to γγ$ and $ H\to b \bar{b}$. We find that $t\bar{t}b\bar{b}$ process can provide more than 3$σ$ disc…
Stringent experimental constraints have raised the lower limit on the masses of squarks to TeV levels, while compatibility with the mass of the Higgs boson provides an upper limit. This two-sided bound has lead to the emergence of Mini-Split theories where gauginos are not far removed from the electroweak scale while scalars are somewhat heavier. This small hierarchy modifies the spectrum of standard anomaly and gauge mediation, leading to Mini-Split deflected anomaly and gauge mediation models. In this paper, we study LHC constraints on these models and their prospects at LHC 14 and a 100 TeV…
The aim of this work is to explore the possibility to discover a fermionic field with mass dimension one, the Elko field, in the 14 TeV Large Hadron Collider (LHC), in processes with missing energy and one jet. We explore the possibility of a triple coupling with the Higgs field, generating also a contribution to the Elko mass term, and suggest some possibilities for future studies in this field.
Doubly charged scalars are common figures in several beyond the Standard Model studies, especially those related to neutrino masses. In this work, we estimate the High-Luminosity (HL-LHC) and High-Energy LHC (HE-LHC) sensitivity to doubly charged scalars assuming they decay promptly and exclusively into charged leptons. Our study focuses on the fit to the same-sign dilepton mass spectra and it is based on proton-proton collisions at $13$ TeV, $14$ TeV and $27$ TeV with integrated luminosity of $\mathcal{L}=139 fb^{-1}, 3 $ab$^{-1}$ and $15$ab$^{-1}$. We find that HL-LHC may probe doubly charge…
We study the Standard Model Higgs and vector boson associated production with large transvese momentum at the 13 TeV LHC, followed by Higgs decay to bottom quark pair. Using mass-drop tagging and filtering techiques, we obtained the cross section of signal and background. The background mainly come from $Vb\bar{b}$, $t\bar{t}$ and single top production. In order to suppress them further, we combined the mass-drop tagging and filtering analysis with $N$-subjettiness jet shape. After performing $N$-subjettiness identification, the significance can be enhanced to 3.52$σ$ with current integrated l…
Using a unified analytic representation for the elastic scattering amplitudes of pp scattering valid for all energy region, the behavior of observables in the LHC collisions in the range $\sqrt{s}$= 2.76 - 14 TeV is discussed. Similarly to the case of 7 TeV data, the proposed amplitudes give excellent description of the preliminary 8 TeV data. We discuss the expected energy dependence of the observable quantities, and present predictions for the experiments at 2.76, 13 and 14 TeV.
Giovannini's parton branching equation is integrated numerically using the 4th-order Runge-Kutta method. Using a simple hadronisation model, a charged-hadron multiplicity distribution is obtained. This model is then fitted to various experimental data up to the TeV scale to study how the Giovannini parameters vary with collision energy and type. The model is able to describe hadronic collisions up to the TeV scale and reveals the emergence of gluonic activity as the centre-of-mass energy increases. A prediction is made for $\sqrt{s}$ = 14 TeV.
We study the process pp->QVX (where Q=t,b and V=g,gamma,Z) through the anomalous interactions of the new heavy quarks at the LHC. Considering the present limits on the masses and mixings, the signatures of the heavy quark anomalous interactions are discussed and analysed at the LHC for the center of mass energy of 13 TeV. An important sensitivity to anomalous couplings kappa_{g}^{t'}/Lambda=0.10 TeV^{-1}, kappa_γ^{t'}/Lambda=0.14 TeV^{-1}, kappa_{Z}^{t'}/Lambda=0.19 TeV^{-1} and kappa_{g}^{b'}/Lambda=0.15 TeV^{-1}, kappa_{Z}^{b'}/Lambda=0.19 TeV$^{-1}, kappa_γ^{b'}/Lambda=0.30 TeV$^{-1} for th…
We analyze the potentiality of hadron colliders to search for large extra dimensions via the production of photon pairs. The virtual exchange of Kaluza--Klein gravitons can significantly enhance this processes provided the quantum gravity scale ($M_S$) is in the TeV range. We studied in detail the subprocesses $q \bar{q} \to γγ$ and $g g \to γγ$ taking into account the complete Standard Model and graviton contributions as well as the unitarity constraints. We show that the Tevatron Run II will be able to probe $M_S$ up to 1.5--1.9 TeV at 2$σ$ level, while the LHC can extend this search to 5.3-…
A study of the production of Mueller-Navelet jets at 13 TeV LHC is presented, including BFKL resummation effects and investigating three different variants of the BLM scale optimization method. It is shown how the cross section and the azimuthal observables are affected by the exclusion of the events where, for a given rapidity interval between the two jets, one of these is produced in the central region.
We investigate simplified models of dark matter with scalar mediators at hadron colliders using the final state topology with 2 jets and missing energy. These models can arise in a wide variety of BSM scenarios including the possibility of the mediator mixing with the Higgs. Our aim is first to determine the projected reach of the LHC and the future circular hadron collider for excluding such models. Secondly, we use the kinematic distributions to extract information on mediator masses. At the 13 TeV LHC we can probe mediator masses up to 750 GeV, and at a 100 TeV collider the reach is increas…
Little Higgs models - which can most easily be thought of as a variant of composite Higgs models - explain a light Higgs boson at 125 GeV as an pseudo-Nambu-Goldstone boson of a spontaneously broken global symmetry. The mechanism of collective symmetry breaking shifts the UV scale of these models to the 10 TeV scale and higher. T-parity is introduced as a discrete symmetry to remove tree-level constraints on the electroweak precision data. Still after run 1 of LHC, electroweak precision observables gave stronger constraints than Higgs data and direct searches. We present a full recast of all a…
我们考虑了在TeV尺度上研究新粒子的可能性，通过在LHC和VLHC上产生顶夸克对来增强与顶夸克的耦合。特别是我们讨论的情况下，中性标量和矢量共振与强相互作用的电弱对称性破缺部门。我们通过施加适当的分波么正性条件和已知的低能量约束来约束这些共振的耦合。在不对初态W玻色子进行近似的情况下，我们通过WW -> tt~对各种模型的新物理信号进行了评估，并优化了信号观测的接受截断。我们的结论是，QCD背景压倒了LHC和200 TeV VLHC中的信号，使得不可能在这些机器上研究TT~通道中的这种类型的物理。
