Search for HZZ′HZZ' couplings at the LHC

New physics models predict the possibility of extra neutral gauge bosons ($Z'$) associated with an extra $U(1)'$ gauge symmetry. We study the couplings of the Higgs boson to the $Z$ boson and $Z'$ boson predicted by the new physics models. The couplings of the $Z'$ boson to quarks can also be investigated through the $Z'q\bar{q}$ interactions. The accessible ranges of the parameter space have been searched for processes $pp\rightarrow HZX$ and $pp\rightarrow HHZX$ at the LHC with $\sqrt{s}=14$ TeV.Comment: 10 pages, 10 figure

Resonant production of diquarks at high energy pp, ep and e+e- colliders

Resonant productions of the first generation scalar and vector diquarks at high energy hadron-hadron (pp), lepton-hadron (ep) and lepton-lepton (e+e-) colliders are investigated. Taking into account the hadronic component of the photon, diquarks can be produced resonantly in the lepton-hadron and lepton-lepton collisions. Production rates, decay widths and signatures of diquarks are discussed using the general, SU(3)_{C} x SU(2)_{W} x U(1)_{Y} invariant, effective Lagrangian. The corresponding dijet backgrounds are examined in the interested invariant mass regions. The attainable mass limits and couplings are obtained for the diquarks that can be produced in hadron collisions and in resolved photon processes. It is shown that hadron collider with center of mass energy sqrt(s)=14 TeV will be able to discover scalar and vector diquarks with masses up to m_{DQ}=9 TeV for quark-diquark-quark coupling alpha_{DQ}=0.1. Relatively, lighter diquarks can be probed at ep and e+e- collisions in more clear environment.Comment: 12 pages, 12 figures, 6 table

Anomalous single production of fourth family up type quark associated with neutral gauge bosons at the LHC

From the present limits on the masses and mixings of fourth family quarks, they are expected to have mass larger than the top quark and allow a large range of mixing of the third family. They could also have different dynamics than the quarks of three families of the Standard Model. The single production of the fourth family up type quark t' has been studied via anomalous production process pp-> t'VX (where V=g,Z,\gamma) at the LHC with the center of mass energy of 7 and 14 TeV. The signatures of such process are discussed within both the SM decay modes and anomalous decay modes of t' quarks. The sensitivity to anomalous coupling kappa/Lambda=0.004 TeV^(-1) can be reached at sqrt(s)=14 TeV and L_(int)=100 pb^(-1).Comment: 15 pages, 9 figure

Single production of excited electrons at future e^-e^+, ep and pp colliders

We analyzed the potential of the LC with $\sqrt{s}=0.5$ TeV, LC$\times$LHC based ep collider with $\sqrt{s}=3.74$ TeV and LHC with $\sqrt{s}=14$ TeV to search for excited electrons through transition magnetic type couplings with gauge bosons. The $e^{\star}\to e\gamma$ signal and corresponding backgrounds are studied in detail.Comment: 11 pages, 11 figures, 3 table

Pair Production of Fourth Family Charged Sleptons at e+e−e^{+}e^{-} Colliders

We study the pair production of $\tilde{l}_{4}$, which is the supersymmetric partner of the fourth family charged lepton, at the $e^{+}e^{-}$ colliders. It is shown that the investigation of this process at ILC/CLIC will give opportunity to differentiate the MSSM with three and four families.Comment: 6 pages, 2 figure

Effects of the FCNC Couplings in Production of New Heavy Quarks within Z

We study the flavor changing neutral current couplings of new heavy quarks through the Z′ models at the LHC. We calculate the cross sections for the signal and the corresponding standard model background processes. Considering the present limits on the mass of new heavy quarks and the Z′ boson, we performed an analysis to investigate the parameter space (mixing and mass) through different Z′ models. For FCNC mixing parameter x=0.1 and the Z′ mass MZ′=2000 GeV and new heavy quark mass mt′=700 GeV at the LHC with s=13 TeV, we find the cross section for single production of new heavy quarks associated with top quarks as 5.8 fb, 3.3 fb, 1.5 fb, and 1.2 fb within the Zη′, Zψ′, ZLP′, and Zχ′ models, respectively. It is shown that the sensitivity would benefit from the flavor tagging

Search for Top Quark FCNC Couplings in Z' Models at the LHC and CLIC

The top quark is the heaviest particle to date discovered, with a mass close to the electroweak symmetry breaking scale. It is expected that the top quark would be sensitive to the new physics at the TeV scale. One of the most important aspects of the top quark physics can be the investigation of the possible anomalous couplings. Here, we study the top quark flavor changing neutral current (FCNC) couplings via the extra gauge boson Z' at the Large Hadron Collider (LHC) and the Compact Linear Collider (CLIC) energies. We calculate the total cross sections for the signal and the corresponding Standard Model (SM) background processes. For an FCNC mixing parameter x=0.2 and the sequential Z' mass of 1 TeV, we find the single top quark FCNC production cross sections 0.38(1.76) fb at the LHC with sqrt{s_{pp}}=7(14) TeV, respectively. For the resonance production of sequential Z' boson and decays to single top quark at the Compact Linear Collider (CLIC) energies, including the initial state radiation and beamstrahlung effects, we find the cross section 27.96(0.91) fb at sqrt{s_{e^{+}e^{-}}}=1(3) TeV, respectively. We make the analysis to investigate the parameter space (mixing-mass) through various Z' models. It is shown that the results benefit from the flavor tagging.Comment: 20 pages, 17 figures, 6 table

Fourth Generation Pseudoscalar Quarkonium Production and Observability at Hadron Colliders

The pseudoscalar quarkonium state, eta_4 1^S_0, formed by the Standard Model (SM) fourth generation quarks, is the best candidate among the fourth generation quarkonia to be produced at the LHC and VLHC. The production of this J^{PC} = 0^{-+} resonance is discussed and the background processes are studied to obtain the integrated luminosity limits for the discovery, depending on its mass.Comment: 13 pages, 4 figures, 5 table

Anomalous Wtb Coupling in ep Collision

The potential of ep collision to prospect for anomalous Wtb vertex is discussed from the single top quark production process $ep\to t\bar{\nu}+X$ for TESLA+HERAp and CLIC+LHC energies. Sensitivities to anomalous couplings $F_{2L}$ and $F_{2R}$, in the case of CLIC+LHC, are shown to be comparable with LHC.Comment: 10 pages, 4 figure