## The LPM effect in sequential bremsstrahlung 2: factorization

## Abstract

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.

- Authors:

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

- Publication Date:

- Research Org.:
- Univ. of Virginia, Charlottesville, VA (United States). Department of Physics

- Sponsoring Org.:
- USDOE Office of Science (SC)

- OSTI Identifier:
- 1437428

- Grant/Contract Number:
- SC0007984

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Journal of High Energy Physics (Online)

- Additional Journal Information:
- Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2016; Journal Issue: 9; Journal ID: ISSN 1029-8479

- Publisher:
- Springer Berlin

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

### Citation Formats

```
Arnold, Peter, Chang, Han-Chih, and Iqbal, Shahin. The LPM effect in sequential bremsstrahlung 2: factorization. United States: N. p., 2016.
Web. doi:10.1007/JHEP09(2016)078.
```

```
Arnold, Peter, Chang, Han-Chih, & Iqbal, Shahin. The LPM effect in sequential bremsstrahlung 2: factorization. United States. doi:10.1007/JHEP09(2016)078.
```

```
Arnold, Peter, Chang, Han-Chih, and Iqbal, Shahin. Tue .
"The LPM effect in sequential bremsstrahlung 2: factorization". United States. doi:10.1007/JHEP09(2016)078. https://www.osti.gov/servlets/purl/1437428.
```

```
@article{osti_1437428,
```

title = {The LPM effect in sequential bremsstrahlung 2: factorization},

author = {Arnold, Peter and Chang, Han-Chih and Iqbal, Shahin},

abstractNote = {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.},

doi = {10.1007/JHEP09(2016)078},

journal = {Journal of High Energy Physics (Online)},

number = 9,

volume = 2016,

place = {United States},

year = {2016},

month = {9}

}

*Citation information provided by*

Web of Science

Web of Science