Related papers: Reconstructing sleptons in cascade-decays at the l…
The rate of the semileptonic decay b to c l v is calculated with order alphas^2 accuracy, as an expansion around the limit of equal masses of the b and c quarks. Recent results obtained around the limit of the c-quark much lighter than b…
A search for a new charged particle X with mass between 0.3 and 2.0 TeV decaying to a W boson and a photon is presented, using proton-proton collision data at a center-of-mass energy of 13 TeV, collected by the CMS experiment and…
The first chapter serves as an introduction to the MSSM. I briefly review the model and explain why stops and sbottoms provide an interesting playground for exploring and testing this model. In the second chapter I discuss stop and sbottom…
Vector-like leptons (VLLs) as one kind of interesting new particles can produce rich phenomenology at low- and high-energy experiments. In the framework of the singlet vector-like leptons with scalar (VLS) model, we investigate the…
We make a Monte Carlo study on compositeness of first generation quarks and leptons using the Drell-Yan distribution in the high dielectron mass region at the Tevatron and LHC energies. The current experimental lower limits on the…
Leptoquarks (LQs) provide very promising solutions to the tensions between the experimental measurements and the SM predictions of $b\to s\ell^+\ell^-$ and $b\to c\tau\nu$ processes. In this case the LQ masses are in general at the TeV…
If R-parity conserving supersymmetry exists below the TeV-scale, new particles will be produced and decay in cascades at the LHC. The lightest supersymmetric particle will escape the detectors, thereby complicating the full reconstruction…
The hint of a pseudoscalar toponium state at the Large Hadron Collider (LHC) opens a new avenue for studying a novel class of QCD (quasi-)bound states with comparable formation and decay times. Compared with charmonium and bottomonium,…
In the Minimal Supersymmetric Standard Model with conserved R-parity, the decays of the next-to-lightest neutralino into the lightest neutralino and two leptons are always involved in each supersymmetric particle decay chain. In this thesis…
Searching for Z' bosons, predicted in GUT-inspired U(1)' gauge models and in the Sequential Standard Model, is one of the main challenges of the experiments carried out at the Large Hadron Collider. Such searches have so far focused on…
Scalar partners of quarks and leptons, predicted in supersymmetric models, are searched for in e^+e^- collisions at centre-of-mass energies between 192GeV and 209GeV at LEP. No evidence for any such particle is found in a data sample of 450…
This article describes the search for pair production of scalar leptoquarks performed by the CMS collaboration using the data from the 2010 proton-proton run of the Large Hadron Collider at a center of mass energy of 7 TeV. The following…
We study the distribution of lepton pairs from the second lightest neutralino decay \tilde{\chi}^0_2-->\tilde{l}l followed by \tilde{l}\to \tilde{\chi}^0_1 l. The distribution of the ratio of lepton transverse momenta A_T shows peak…
The ATLAS experiment identifies and reconstructs muons with two high precision tracking systems, the Inner Detector and the Muon Spectrometer, which provide independent measurements of the muon momentum. This paper summarizes the…
A good knowledge of the luminosity spectrum is mandatory for many measurements at future e+e- colliders. As the beam-parameters determining the luminosity spectrum cannot be measured precisely, the luminosity spectrum has to be measured…
In supersymmetric theories with R-parity breaking, sleptons could be produced singly in $e^+e^-$ collisions at LEP2 and in $q\bar{q}$ annihilation at the Tevatron through interactions in which two quark or two lepton fields are coupled to a…
The scalar partner of the top quark (the stop) is relatively light in many models of supersymmetry breaking. We study the production of stops at the Large Hadron Collider (LHC) and their subsequent decays through baryon-number violating…
Heavy lepton singlets $N$ slightly mixed with a standard neutrino $\nu_\ell$ are usually searched for at the LHC in the trilepton plus $p_{\rm T}^{\rm miss}$ channel: $pp \to W^+ \to \ell^+ N$ with $N\to \ell^- W^+ \to \ell^- \ell'^+ \nu$.…
We demonstrate the potential of fully leptonic cascade decays of a heavy neutral Higgs boson through vectorlike leptons as a simultaneous probe for extended Higgs sectors and extra matter particles at the LHC. The processes we explore are…
We report the results of a search for pair production of scalar bottom quarks (sbottom) and scalar third-generation leptoquarks in 5.2 fb-1 of ppbar collisions at the D0 experiment of the Fermilab Tevatron Collider. Scalar bottom quarks are…