Abstract
We calculate the O( {alpha}_s^2 ) corrections to the primary massive quark jet functions in Soft-Collinear Effective Theory (SCET). They are an important ingredient in factorized predictions for inclusive jet mass cross sections initiated by massive quarks emerging from a hard interaction with smooth quark mass dependence. Due to the effects coming from the secondary production of massive quark-antiquark pairs there are two options to define the SCET jet function, which we call universal and mass mode jet functions. They are related to whether or not a soft mass mode (zero) bin subtraction is applied for the secondary massive quark contributions and differ in particular concerning the infrared behavior for vanishing quark mass. We advocate that a useful alternative to the common zero-bin subtraction concept is to define the SCET jet functions through subtractions related to collinear-soft matrix elements. This avoids the need to impose additional power counting arguments as required for zero-bin subtractions. We demonstrate how the two SCET jet function definitions may be used in the context of two recently developed factorization approaches to treat secondary massive quark effects. We clarify the relation between these approaches and in which way they are equivalent. Our two-loop calculation involves interesting technical subtleties related to spurious rapidity divergences and infrared regularization in the presence of massive quarks.
Highlights
Of low-energy hadronization effects for processes dominated by the strong interaction
We advocate that a useful alternative to the common zero-bin subtraction concept is to define the Soft-Collinear Effective Theory (SCET) jet functions through subtractions related to collinear-soft matrix elements
In the context of bottom and charm quark production in hard collisions the SCET regime p2 ∼ p2 − m2 ∼ m2 is essentially the only one that can ever arise in practical applications where quark mass effects are important due to the sizable momentum smearing coming from non-perturbative effects [13]
Summary
Quark jet functions in SCET are based on the vacuum correlator of two SCET jet fields, encoding the inclusive collinear dynamics of quark fields coherently accounting for the collinear gluon radiation from all other color sources of a process. [22, 26] (originally developed for massless primary quark jet functions) where universal hard, jet and soft (and in principle invariant mass dependent beam) functions can be defined valid for any value of m2, with respect to the other dynamic scales and the renormalization scale μ. This approach makes the μ-evolution in n or (n + 1). We stress that the form of the collinear-soft ME of eq (2.7) and the two options of using either eq (2.10) or eq (2.11) for IR finite jet functions in the presence of massive quarks can be applied in a fully equivalent way for invariant mass dependent beam functions [38] and the bHQET jet function [12, 14].5 The approach applies in an analogous way for the treatment of massive gauge bosons which is conceptually related to the issues of secondary quark mass effects as was discussed in [22]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
