The LPM effect in sequential bremsstrahlung 2: factorization

Journal Article · 13 September 2016 · Journal of High Energy Physics (Online)

DOI: https://doi.org/10.1007/JHEP09(2016)078 · OSTI ID:1437428

Arnold, Peter ^[1]; Chang, Han-Chih ^[1]; Iqbal, Shahin ^[2]

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1. Univ. of Virginia, Charlottesville, VA (United States). Department of Physics
2. Univ. of Virginia, Charlottesville, VA (United States). Department of Physics; National Centre for Physics, Quaid-i-Azam University CampusIslamabad (Pakistan)

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; q approximation; large N _c; and neglect for the moment of processes involving 4-gluon ver-tices) and explicitly compute the correction Δ dΓ/dx dy due to overlapping formation times.

• Research Organization: Univ. of Virginia, Charlottesville, VA (United States). Department of Physics
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: SC0007984
• OSTI ID: 1437428
• Journal Information: Journal of High Energy Physics (Online), Vol. 2016, Issue 9; ISSN 1029-8479
• Publisher: Springer BerlinCopyright Statement
• Country of Publication: United States
• Language: English