Usingt→bb¯cto search for new physics

Abstract

We consider new-physics (NP) contributions to the decay t → bbc. We parameterize the NP couplings by an effective Lagrangian consisting of 10 Lorentz structures. We show that the presence of NP can be detected through the measurement of the partial width. A partial identification of the NP can be achieved through the measurements of a forward-backward-like asymmetry, a topquark-spin-dependent asymmetry, the partial rate asymmetry, and a triple-product asymmetry.These observables, which vanish in the standard model, can all take values in the 10-20% range in the presence of NP. Since |V tb V cb | |V ts V cs |, most of our results also hold, with small changes, for

Impact ofZ′and universal extra dimension parameters on different asymmetries inBs→ϕℓ+ℓAhmed1, Aslam2, Paracha3 2013Phys. Rev. D

“…(11) we can see that the value of P TN comes from the imaginary part of various Wilson Coefficients, and therefore-as expected-its value is too small to measure. This is obvious from Figs.…”

“…In this context there have been numerous papers examining the possible NP FCNC scenarios through the various b ! s processes [11].…”

MeasuringCP-violating observables in rare top decays at the LHC

“…This paper builds on the work done in Refs. [5,7,8], in which (NP) contributions to t → bbc were considered. Because this decay is suppressed in the SMthe amplitude is proportional to V cb (∼ 0.04) -the NP effects could potentially be sizeable.…”

“…The colour indices in the above expressions are assumed to contract in the same manner as those in the SM; Ref. [5] contains an analysis of the case in which the indices contract differently than in the SM.…”

“…These same two parameter combinations were analyzed in Ref. [5], although the notation in that paper was somewhat different. In addition, for Im(X T LL X S * LL + X T RR X S * RR ) it was assumed there that the spin of the top quark could be measured (obviously a simplifying assumption).…”