NLO QCD corrections to tW ′ and tZ ′ production in forward-backward asymmetry models

Abstract

We consider Z and W models recently proposed to explain the top forward-backward asymmetry at the Tevatron. We present the next-to-leading order QCD corrections to associated production of such vector bosons together with top quarks at the Large Hadron Collider, for centre-of-mass energies of 7 and 8 TeV. The corrections are significant, modifying the total production cross-section by 30-50%. We consider the effects of the corrections on the top and vector-boson kinematics. The results are directly applicable to current experimental searches, for both the ATLAS and CMS collaborations.

Heavy neutrinos and thepp→lljjCMS data

“…As one can see from (15) and Fig. 2, there exists a CP phase for which (σ ++ ee + σ −− ee )/σ +− ee = r as suggested by CMS data (1).…”

Search for resonant top quark plus jet production intt¯+jetsevents with the ATLAS detector inppcollisions atCollaboration1 2012Phys. Rev. DSelf Cite

“…As shown in Ref. [6], the production mechanism in pp collisions mainly involves quarks rather than antiquarks at ffiffi ffi s p ¼ 7 TeV, even for relatively low mass particles. The larger number of quarks relative to antiquarks produced in the initial state at the LHC leads to a resonance R that decays predominantly to either the t þ jet or " t þ jet final state, where baryon number conservation restricts the models that are available.…”

Interpretations and implications of the top quark rapidity asymmetriesAFBtandAFBℓ

“…First, contributions from tt processes with extra partons in the final state are not included in the estimation. They might be important for some new physics models especially for A C [22,23,36]. Second, there are models in which A t F B at Tevatron is a residue of the balance between contributions from uū and dd initial states [83].…”

“…3. However, a complete analysis must take into account interference between tt + j in the SM and the W ′ model [35,37] and a large enhancement from NLO QCD corrections (K−factor ∼ 1.3 − 1.5 [36]) . We defer it for future study.…”

“…These models usually postulate the existence of new states, whether in the direct-channel coupling to tt, or exchanged in a cross-channel and coupling the top quark to first-and/or second-generation quarks. Examples include flavor-changing Z ′ , W ′ [25][26][27][28][29][30][31][32][33][34][35][36][37] and axigluon G ′ models, among others [37,.…”