Same-sign WW production in proton-nucleus collisions at the LHC as a signal for double parton scattering

The production of same-sign W-boson pairs from double parton scatterings (DPS) in proton-lead (p-Pb) collisions at the CERN Large Hadron Collider is studied. The signal and background cross sections are estimated with next-to-leading-order perturbative QCD calculations using nuclear parton distribution functions for the Pb ion. At sNN=8.8 TeV the cross section for the DPS process is about 150 pb, i.e. 600 times larger than that in proton-proton collisions at the same centre-of-mass energy and 1.5 times higher than the p-Pb→W±W±+2-jets single-parton background. The measurement of such a process, where 10 events with fully leptonic Wʼs decays are expected after cuts in 2 pb−1, would constitute an unambiguous DPS signal and would help determine the effective σeff parameter characterising the transverse distribution of partons in the proton.