Searching for top flavor violating resonances

Abstract

We study new top flavor violating resonances that are singly produced in association with a top at the LHC. Such top flavor violating states could be responsible for the Tevatron top forward-backward asymmetry. Since top flavor violating states can directly decay to a top (or antitop) and jet, and are produced in conjunction with another (oppositely charged) top, the direct signature of such states is a tj (or " tj) resonance in t " tj events. In general, these states can be very light and have Oð1Þ couplings to the top sector so that they are copiously produced. We present a search strategy and estimate the discovery potential at the early LHC by implementing the strategy on simulated data. For example, with 1 fb À1 at 7 TeV, we estimate that a W 0 coupling to d R " t R can be constrained at the 3 level for g R ¼ 1 and m W 0 ¼ 200 GeV, weakening to g R ¼ 1:75 for m W 0 ¼ 600 GeV. With the search we advocate here, a bound at a similar level could be obtained for top flavor violating Z 0 s, as well as triplet and sextet diquarks.

Diquark contributions to top quark charge asymmetry at the Tevatron and LHC

“…We would like to thank the organizers and lecturers at the KIAS school on MadGraph for LHC physics simulation (Oct. [24][25][26][27][28][29] 2011, KIAS, Soul) and at the 2011 IPMU-YITP School and Workshop on Monte Carlo Tools for LHC (Sept. 5-10, 2011, Kyoto University, Kyoto) where we learned basics of hadron collider physics, which are applied in this study. J.N.…”

Single vectorlike quark production at the LHC

“…An explanation with physics above ∼ 1 TeV seems disfavoured by data [2]. If it is below this energy, then a large width could be the key reason why it has escaped detection in the usual observables.…”

“…However, any candidate responsible for the asymmetry has to be carefully disguised, as its large contribution there should not translate into any significant departure from the SM in other related observables. In particular, the tt total cross section, its invariant mass distribution, dijet production, same sign top production, or the tt charge asymmetry at the LHC are observables where correlated anomalies could be expected [2].…”

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

“…The LO diagrams are shown in figure 1. Following [29], we define the coupling of these bosons to the top quark according to the Lagrangians L W = P tD √ 2D γ µ g R P R tW + h.c.;…”

“…Note also that coupling and parameter definitions (including overall normalisations) differ in the above literature. Here we will focus our discussion explicitly on the model of [29].…”