Abstract
The production of high-mass, color-singlet particles in hadron collisions is universally accompanied by initial state QCD radiation that is predominantly soft with respect to the hard process scale Q and/or collinear with respect to the beam axis. At TeV-scale colliders, this is in contrast to top quark and multijet processes, which are hard and central. Consequently, vetoing events with jets possessing transverse momenta above pTVeto in searches for new color-singlet states can efficiently reduce non-singlet backgrounds, thereby increasing experimental sensitivity. To quantify this generic observation, we in-vestigate the production and leptonic decay of a Sequential Standard Model W′ boson at the 13 TeV Large Hadron Collider. We systematically consider signal and background processes at next-to-leading-order (NLO) in QCD with parton shower (PS) matching. For color-singlet signal and background channels, we resum Sudakov logarithms of the form αsj(pTVeto) logk(Q/pTVeto) up to next-to-next-to-leading logarithmic accuracy (NNLL) with NLO matching. We obtain our results using the MadGraph5_aMC@NLO and MadGraph5_aMC@NLO-SCET frameworks, respectively. Associated Universal Feyn-Rules Output model files capable of handling NLO+PS- and NLO+NNLL-accurate computations are publicly available. We find that within their given uncertainties, both the NLO+PS and NLO+NNLL(veto) calculations give accurate and consistent predictions. Consequently, jet vetoes applied to color-singlet processes can be reliably modeled at the NLO+PS level. With respect to a b-jet veto of pTVeto = 30 GeV, flavor-agnostic jet vetoes of pTVeto = 30 − 40 GeV can further reduce single top and toverline{t} rates by a factor of 2-50 at a mild cost of the signal rate. Jet vetoes can increase the signal-to-noise ratios by roughly 10% for light W′ boson masses of 30 − 50 GeV and 25%-250% for masses of 300-800 GeV.
Highlights
Whose leading order (LO) diagrams are shown in figure 1
That due to the universality of QCD radiation in the soft and collinear limits, jet vetoes are generically applicable to any color-singlet process that results in colorless final-state particles and in which QCD processes are a non-negligible fraction of the background
The origin of tiny nonzero neutrinos masses, the particle nature of dark matter and the weakness of gravity are longstanding issues, among others, that can potentially be understood and studied at collider experiments via the probes for the existence of new W and Z gauge bosons. Due to their color-singlet nature, the QCD radiation pattern of W and Z boson production at hadron colliders is intrinsically softer than the W /Z mass scale and more collinear with respect to the beam axis than the pattern associated with the leading color non-singlet background processes
Summary
We take a simplified approach to modeling physics beyond the Standard Model We do this by minimally extending the SM to construct a general effective framework that can be used for studying various models featuring extra colorless gauge bosons that couple to. In the canonical SSM, the overall normalizations are further trivially fixed as κqL, = 1, κqR = 0 and ζZf SSM = 1 This parameterization can be used to describe any model featuring extra colorless, massive vector bosons, provided there is no new source of flavor violation with respect to the SM. The thickness of each curve in the main panel of figure 2 corresponds to the residual scale uncertainty as evaluated when varying μf and μr independently by a factor of two up and down with respect to the central scale μ0. Where the largest rates and residual scale uncertainties correspond to the smallest SSM boson masses. The factor of three corresponds to three generations with
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