The LPM effect in sequential bremsstrahlung 2: factorization

Fuente: arXiv
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Autores principales: Arnold, Peter, Chang, Han-Chih, Iqbal, Shahin
Formato: Preprint
Publicado: 2016
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author Arnold, Peter
Chang, Han-Chih
Iqbal, Shahin
author_facet Arnold, Peter
Chang, Han-Chih
Iqbal, Shahin
contents The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue analysis of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper analyzes the subtle problem of how to precisely separate overlapping double splitting (e.g.\ overlapping double bremsstrahlung) from the case of consecutive, independent bremsstrahlung (which is the case that would be implemented in a Monte Carlo simulation based solely on single splitting rates). As an example of the method, we consider the rate of real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; $\hat q$ approximation; large $N_c$; and neglect for the moment of processes involving 4-gluon vertices) and explicitly compute the correction $Δ\,dΓ/dx\,dy$ due to overlapping formation times.
format Preprint
id arxiv_https___arxiv_org_abs_1605_07624
institution arXiv
publishDate 2016
record_format arxiv
spellingShingle The LPM effect in sequential bremsstrahlung 2: factorization
Arnold, Peter
Chang, Han-Chih
Iqbal, Shahin
High Energy Physics - Phenomenology
Nuclear Theory
The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue analysis of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper analyzes the subtle problem of how to precisely separate overlapping double splitting (e.g.\ overlapping double bremsstrahlung) from the case of consecutive, independent bremsstrahlung (which is the case that would be implemented in a Monte Carlo simulation based solely on single splitting rates). As an example of the method, we consider the rate of real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; $\hat q$ approximation; large $N_c$; and neglect for the moment of processes involving 4-gluon vertices) and explicitly compute the correction $Δ\,dΓ/dx\,dy$ due to overlapping formation times.
title The LPM effect in sequential bremsstrahlung 2: factorization
topic High Energy Physics - Phenomenology
Nuclear Theory
url https://arxiv.org/abs/1605.07624