Monday, May 27, 2013

1305.5596 (CMS Collaboration)

Study of exclusive two-photon production of W(+)W(-) in pp collisions at
sqrt(s)=7 TeV and constraints on anomalous quartic gauge couplings

CMS Collaboration
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(+/-)e(-/+) vertex with no additional associated charged tracks and dilepton transverse momentum pt(mu(+/-)e(-/+))>30 GeV. Two events passing all selection requirements are observed in the data, compared to a standard model expectation of 2.2+/-0.4 signal events with 0.84+/-0.15 background. The tail of the dilepton pt distribution is studied for deviations from the standard model. No events are observed with pt > 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 10E-4.
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