/ hep-ex CMS-FSQ-12-010

Study of exclusive two-photon production of $W^+W^-$ in pp collisions at $\sqrt{s}$ = 7 TeV and constraints on anomalous quartic gauge couplings

Abstract: A search for exclusive or quasi-exclusive $W^+ W^-$ production by photon-photon interactions, $pp \to p^{(*)}W^+W^-p^{(*)}$, at $\sqrt{s}$ = 7 TeV is reported using data collected by the CMS detector with an integrated luminosity of 5.05 inverse femtobarns. Events are selected by requiring a $\mu^{\pm}e^{\mp}$ vertex with no additional associated charged tracks and dilepton transverse momentum $p_T(\mu^{\pm}e^{\mp}) \gt$ 30 GeV. Two events passing all selection requirements are observed in the data, compared to a standard model expectation of 2.2$\pm$0.4 signal events with 0.84$\pm$0.15 background. The tail of the dilepton $p_T$ distribution is studied for deviations from the standard model. No events are observed with $p_T \gt$ 100 GeV. Model-independent upper limits are computed and compared to predictions involving anomalous quartic gauge couplings. The limits on the parameters $a^{W}_{0,C}/\Lambda^2$ with a dipole form factor and an energy cutoff $\Lambda_{cutoff}$ = 500 GeV are of the order of 10$^{-4}$.

Note: Submitted to JHEP

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