Related papers: Leptophobic $Z'$ in Models with Multiple Higgs Dou…
A measurement of the production cross section for a top quark pair in association with a $Z$ boson ($t\bar{t}Z$) is presented in this PhD thesis. Final states with exactly three charged leptons (electrons or muons) are used, taking into…
A detailed analysis of ZZ production at the upgraded Fermilab Tevatron and the CERN Large Hadron Collider is presented for general ZZZ and ZZ\gamma couplings. Deviations from the Standard Model gauge theory structure for each of these can…
The determination of the $Zb\bar{b}$ coupling in experiments has been a long-standing challenge, as the limited precision of off $Z$-pole measurements at the LEP has resulted in two degenerate solutions remained to be resolved. In this…
A multi-Higgs model with an extra neutral gauge boson ($Z'$) is introduced. One scalar Higgs boson ($H_2$) in this model decays dominantly into a photon pair. The $Z'$ decay to $\mu^+\mu^-$ gets a much larger branching ratio than the $Z$…
The constraints from the measurements of the $B\to X_s\gamma$ decay rate on the parameter space of 3-Higgs Doublet Models (3HDMs), where all the doublets have non-zero vacuum expectation values, are studied at the next-to-leading order in…
The tension among measurements of $V_{us}$ from different channels, the so-called Cabibbo Angle Anomaly, can be interpreted as a signal of lepton flavor universality (LFU) violation in the $W$ boson couplings. We investigate this issue in…
We study and compare the discovery potential for heavy neutral gauge bosons (Z') at the various $e^+e^-$ and $\mu^+\mu^-$ colliders that have been proposed. Typical search limits for the e^+e^- colliders are 2-10 times sqrt{s} with the…
A search for pair-produced heavy vector-like charge-2/3 quarks, T, in pp collisions at a center-of-mass energy of 7 TeV, is performed with the CMS detector at the LHC. Events consistent with the flavor-changing-neutral-current decay of a T…
We consider low-scale leptogenesis via right-handed neutrinos $N$ coupled to a $Z'$ boson, with gauged $U(1)_{B-L}$ as a simple realization. Keeping the neutrinos sufficiently out of equilibrium puts strong bounds on the $Z'$ coupling…
If there is an extra U(1) gauge symmetry broken at low energies, then it may be possible from the charges of the known quarks and leptons under this U(1) to make inferences about how much gauge unification occurs at high scales and about…
A Fermiophobic Higgs boson can arise in models with an extended Higgs sector, such as models with scalars in an isospin triplet representation. In a specific model with a scalar triplet and spontaneous violation of lepton number induced by…
The complex two-Higgs doublet model (C2HDM) is one of the simplest extensions of the Standard Model with a source of CP-violation in the scalar sector. It has a $\mathbb{Z}_2$ symmetry, softly broken by a complex coefficient. There are four…
A vector boson $W_{1}^{\mu}$ with the quantum numbers $\left(\boldsymbol{3},1\right)$ under $SU\left(2\right)_{L}\times U(1)_{Y}$ could in principle couple with the Higgs field via the renormalizable term $W_{1}^{\mu*}HD_{\mu}H$. This…
A search for the production of pairs of heavy Majorana neutrinos (N$_\ell$) from the decays of Z' bosons is performed using the CMS detector at the LHC. The data were collected in proton-proton collisions at a center-of-mass energy of…
We propose a new non-universal $U(1)'$ extension of the standard model with the addition of three exotic quark singlets, two scalar singlets and one additional scalar doublet. We obtain family dependent couplings with a new $Z'$ boson in…
We perform a detailed hadron-level study on the sensitivity of Higgs boson pair production via the $WW^{*}WW^{*}$ channel with the final state $3 \ell 2 j$ + missing $E_T$ at the LHC with the collision energy $\sqrt{S} = 14$ TeV and a…
The first search for a heavy charged vector boson in the final state with a tau lepton and a neutrino is reported, using 19.7 inverse femtobarns of LHC data at sqrt(s) = 8 TeV. A signal would appear as an excess of events in kinematic…
The resonant excesses around 2 TeV reported by the ATLAS Collaboration can be explained in the left-right model, and the tight constraints from lepton plus missing energy searches can be evaded if the $SU(2)_R$ gauge symmetry is…
We propose an anomaly free gauged U$(1)$ extension of the SM where three right handed heavy neutrinos, being charged under the general U$(1)$ gauge group, are introduced to explain the origin of the tiny neutrino mass through the seesaw…
We explore possible signatures for heavy neutrinos and neutral gauge boson, Z', in TeV scale B-L extension of the Standard Model (BLSM) with inverse seesaw mechanisms at the Large Hadron Collider. We show that due to new decay channels of…