An Explanation of the WW Excess at the LHC by Jet-Veto Resummation

Abstract

The WW production cross section measured at the LHC has been consistently exhibiting a mild excess beyond the SM prediction, in both ATLAS and CMS at both 7-TeV and 8-TeV runs. We provide an explanation of the excess in terms of resummation of large logarithms that arise from a jet-veto condition, i.e., the rejection of high-pT jets with pT > pT(veto) that is imposed in the experimental analyses to reduce backgrounds. Jet veto introduces a second mass scale pT(veto) to the problem in addition to the invariant mass of the WW pair. This gives rise to large logarithms of the ratio of the two scales that need to be resummed. Such resummation may not be properly accounted for by the Monte Carlo simulations used in the ATLAS and CMS studies. Those logarithms are also accompanied by large pi^2 terms when the standard, positive sign is chosen for the squared renormalization scale. We analytically resum the large logarithms including the pi^2 terms in the framework of soft collinear effective theory (SCET), and demonstrate that the SCET calculation not only reduces the scale uncertainties of the SM prediction significantly but also renders the theory prediction well compatible with the experiment. We find that resummation of the large logarithms and that of the pi^2 terms are both comparably important.

A minor bug in the beam functions corrected. The final results are virtually unchanged from those in the published version

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Cited by in corpus (20)

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• Measurement of the inclusive and differential Higgs boson production cross sections in the leptonic WW decay mode at $\sqrt{s}=$ 13 TeV
• $W^{+}{W}^{-}$ production at the LHC: NLO QCD corrections to the loop-induced gluon fusion channel
• Measurements of the Higgs boson production cross section and couplings in the W boson pair decay channel in proton-proton collisions at $\sqrt{s}$ = 13 TeV
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• Quark and gluon two-loop beam functions for leading-jet $p_T$ and slicing at NNLO
• Refining the GENEVA method for Higgs boson production via gluon fusion
• The NNLO quark beam function for jet-veto resummation
• Constraints on anomalous Higgs boson couplings from its production and decay using the WW channel in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Transverse momentum resummation at N3LL+NNLO for diboson processes
• Distinctive Heavy Higgs Decays
• A New Observable for Identifying Dijet Resonances
• Theory Summary and Prospects
• Search for dark matter particles in W${}^{+}$W${}^{-}$ events with transverse momentum imbalance in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Threshold resummation for $W$-boson pair production at NNLO+NNLL
• Using Random Forests to Classify W+W- and ttbar Events
• The analytic two-loop soft function for leading-jet $p_T$