659 research outputs found

    Dimension-six anomalous tqγtq\gamma couplings in γγ\gamma \gamma collision at the LHC

    Get PDF
    We have investigated the flavor changing top quark physics on the dimension-six anomalous tqγtq\gamma (q=u,cq=u,c) couplings through the process pp→pγγp→ptqˉppp\to p\gamma \gamma p\to p t\bar{q}p at the LHC by considering different forward detector acceptances. In this paper, we have taken into account and examine the effects of top quark decay. The sensitivity bounds on the anomalous couplings and, t→qγt\to q\gamma branching ratio have been obtained at the 95%95\% confidence level for the effective lagrangian approach. Besides, we have investigated the effect of the anomalous couplings on single top quark spin asymmetry.Comment: 24 pages, 8 figures. This version matches the published version in Nucl.Phys.

    Search for the Anomalous Interactions of Up-Type Heavy Quarks in γγ\gamma \gamma Collision at the LHC

    Get PDF
    We investigate the anomalous interactions of heavy up-type quark t' in a γγ\gamma \gamma collision at the LHC. We have obtained 95% confidence level(CL)limit of t′qγt'q \gamma anomalous coupling by taking into account three forward detector acceptances: 0.0015<ξ<0.150.0015<\xi<0.15,0.0015<ξ<0.50.0015<\xi<0.5, and 0.1<ξ<0.50.1<\xi<0.5.Comment: 16 pages, 3 figures, 3 table

    Probe of unparticles at the LHC in exclusive two lepton and two photon production via photon-photon fusion

    Full text link
    The exclusive production pp->pXp is known to be one of the most clean channels at the LHC. We investigate the potential of processes pp -> p l-l+ p and pp-> p gamma gamma p to probe scalar and tensor unparticles by considering three different forward detector acceptances; 0.0015<xi<0.15, 0.0015<xi<0.5 and 0.1<xi<0.5. We obtain 95% confidence level sensitivity limits on the unparticle couplings for various integrated luminosities.Comment: 27 pages, 17 figure

    Probe of the Anomalous Quartic Couplings with Beam Polarization at the CLIC

    Get PDF
    We have investigated the anomalous quartic couplings defined by the dimension-8 operators in semileptonic decay channel of the e+e−→νeW−W+νˉee^{+}e^{-}\rightarrow \nu_{e} W^{-} W^{+} \bar{\nu}_{e} process for unpolarized and polarized electron (positron) beam at the Compact Linear Collider. We give the 95%95\% confidence level bounds on anomalous fS0Λ4\frac{f_{S0}}{\Lambda^{4}}, fS1Λ4\frac{f_{S1}}{\Lambda^{4}} and fT0Λ4\frac{f_{T0}}{\Lambda^{4}} couplings for various values of the integrated luminosities and center-of-mass energies. The best sensitivities obtained on anomalous fS0Λ4\frac{f_{S0}}{\Lambda^{4}}, fS1Λ4\frac{f_{S1}}{\Lambda^{4}} and fT0Λ4\frac{f_{T0}}{\Lambda^{4}} couplings through the process e+e−→νeW−W+νˉee^{+}e^{-}\rightarrow \nu_{e} W^{-} W^{+} \bar{\nu}_{e} with beam polarization at s=3\sqrt{s}=3 TeV and an integrated luminosity of Lint=2000L_{int}=2000 fb−1^{-1} are [−4.05; 3.67]×10−12[-4.05;\, 3.67]\times 10^{-12} GeV−4^{-4}, [−3.08; 2.12]×10−12[-3.08; \, 2.12]\times 10^{-12} GeV−4^{-4}, [−1.98; 0.64]×10−13[-1.98; \, 0.64]\times 10^{-13} GeV−4^{-4}, which show improvement over the current bounds.Comment: 8 pages, 7 figures and 8 tables, published versio

    Anomalous WWγWW\gamma couplings with beam polarization at the Compact Linear Collider

    Get PDF
    We study the anomalous WWγWW\gamma couplings at the Compact Linear Collider through the processes e+e−→W+W−e^{+}e^{-}\to W^+W^-, e−e+→e−γ∗e+→e+νeW−e^{-}e^{+} \to e^{-} \gamma^{*} e^{+} \to e^{+} \nu_{e} W^- and e−e+→e−γ∗γ∗e+→e−W+W−e+e^{-}e^{+}\to e^{-} \gamma^{*} \gamma^{*} e^{+} \to e^{-} W^+ W^- e^{+} (γ∗ (\gamma^{*} is the Weizsacker-Williams photon). We give the 95\% confidence level limits for unpolarized and polarized electron (positron) beam on the anomalous couplings for various values of the integrated luminosities and center-of-mass energies. We show that the obtained limits on the anomalous couplings through these processes can highly improve the current experimental limits. In addition, our limits with beam polarization are approximately two times better than the unpolarized case.Comment: Tables and references adde

    The impact of excited neutrinos on ννˉ→γγ\nu \bar{\nu}\to \gamma\gamma process

    Get PDF
    We examine the effect of excited neutrinos on the annihilation of relic neutrinos with ultra high energy cosmic neutrinos for the ννˉ→γγ\nu \bar{\nu}\to \gamma\gamma process. The contribution of the excited neutrinos to the neutrino-photon decoupling temperature are calculated. We see that photon-neutrino decoupling temperature can be significantly reduced below the obtained value of the Standard Model with the impact of excited neutrinos.Comment: 11 pages, 3 figures, published versio

    Search for invisible dark photon in γe\gamma e scattering at future lepton colliders

    Full text link
    For the first time, the production of a massive dark photon (DP) in the γe−\gamma e^- scattering at the future lepton colliders ILC, CLIC, and CEPC is examined. The invisible decay mode of the DP is addressed. We have studied both the unpolarized scattering and the collision of the Compton backscattered photons with the polarized electron. The missing energy distributions are shown. We have considered the wide range 10 GeV -- 1000 GeV of the DP mass mA′m_{A'}. The excluded regions at the 95\% C.L. in the plane (ε,mA′)(\varepsilon, m_{A'}), where ε\varepsilon is the kinetic mixing parameter, are obtained.Comment: 24 pages, 10 figures; one equation and two references are adde
    • …
    corecore