SCET approach to top quark decay

TL;DR

This paper applies soft-collinear effective theory (SCET) to analyze QCD corrections in top quark decay involving a B hadron, deriving a new factorization formula and calculating a fragmenting jet function at next-to-leading order.

Contribution

The work introduces a novel fragmenting jet function within SCET for top decay and provides an analytic formula for the distribution, generalizable to other heavy hadron decays.

Findings

Derived a factorization theorem based on SCET.

Calculated the fragmenting jet function to NLO in α_s.

Summed large logarithms using RGE for improved accuracy.

Abstract

In this work we study QCD corrections to the top quark doubly decay rate with a detected $B$ hadron containing a $b$ quark. We focus on the regime among which the emitted $W$ boson nearly carries its maxim energy. The tool that we use here is the soft-collinear effective theory (SCET). The factorization theorem based on SCET indicates a novel fragmenting jet function. We calculate this function to next-to-leading order in $\alpha_s$. Large logarithms due to several well separated scale are summed up using the renormalization group equation (RGE). Finally we reach an analytic formula for the distribution which could easily be generalized to other heavy hadron decay.