Zero bin subtraction in the small q_T expansion beyond the leading power

by Wan-Li Ju (INFN Milano), Wanli Ju

Monday 23 Oct 2023, 11:00 → 12:00 Europe/Zurich

Aula Caldirola (Università degli Studi di Milano)

The asymptotic behaviour in the small q_T regime on the process pp -> H(Z)+X is of both theoretical and phenomenological interest. Within the context of expansion by regions, those singular contributions can be associated with a set of dynamic regions from the integration range accompanied by an appropriate subtraction procedure to remove the possible overlappings in between.  Since, in the hybrid space-momentum representation, this kind of overlapping is usually related to the zeroth-bin of the label momentum, the subtraction here is also referred to as the zero-bin subtraction. 

 

In the recent decades, the zero-bin subtraction has been investigated extensively in the leading power approximation.  Very recently, there are also formalisms developed for the subleading power contribution (suppressed by O(q²_T) w.r.t. the leading case).  In pursuit of this theme, in this report, I will introduce an algorithm to construct zero-bin subtrahends that can be applicable onto the NLO q_T spectra at an arbitrary power on a generic choice of rapidity-divergence regulator. Following this tactic, an unified description will be presented on the analytic expressions conducted by the exponential regulator and the pure-rapidity one up to the sub-subleading power (suppressed by O(q_T⁴) w.r.t. the leading case) as two representative examples. Eventually, I will compare the numeric results derived from the power expansion against those from the full theory. 

WJU_23Oct2023.pdf