## Non-global logarithms, factorization, and the soft substructure of jets

## Abstract

An outstanding problem in QCD and jet physics is the factorization and resummation of logarithms that arise due to phase space constraints, so-called non-global logarithms (NGLs). In this paper, we show that NGLs can be factorized and resummed down to an unresolved infrared scale by making sufficiently many measurements on a jet or other restricted phase space region. Resummation is accomplished by renormalization group evolution of the objects in the factorization theorem and anomalous dimensions can be calculated to any perturbative accuracy and with any number of colors. To connect with the NGLs of more inclusive measurements, we present a novel perturbative expansion which is controlled by the volume of the allowed phase space for unresolved emissions. Arbitrary accuracy can be obtained by making more and more measurements so to resolve lower and lower scales. We find that even a minimal number of measurements produces agreement with Monte Carlo methods for leading-logarithmic resummation of NGLs at the sub-percent level over the full dynamical range relevant for the Large Hadron Collider. Here, we also discuss other applications of our factorization theorem to soft jet dynamics and how to extend to higher-order accuracy.

- Authors:

- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Center for Theoretical Physics

- Publication Date:

- Research Org.:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

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

- OSTI Identifier:
- 1455239

- Grant/Contract Number:
- SC0011090; SC0012567

- 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: 2015; 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; Resummation; QCD

### Citation Formats

```
Larkoski, Andrew J., Moult, Ian, and Neill, Duff. Non-global logarithms, factorization, and the soft substructure of jets. United States: N. p., 2015.
Web. doi:10.1007/JHEP09(2015)143.
```

```
Larkoski, Andrew J., Moult, Ian, & Neill, Duff. Non-global logarithms, factorization, and the soft substructure of jets. United States. doi:10.1007/JHEP09(2015)143.
```

```
Larkoski, Andrew J., Moult, Ian, and Neill, Duff. Tue .
"Non-global logarithms, factorization, and the soft substructure of jets". United States. doi:10.1007/JHEP09(2015)143. https://www.osti.gov/servlets/purl/1455239.
```

```
@article{osti_1455239,
```

title = {Non-global logarithms, factorization, and the soft substructure of jets},

author = {Larkoski, Andrew J. and Moult, Ian and Neill, Duff},

abstractNote = {An outstanding problem in QCD and jet physics is the factorization and resummation of logarithms that arise due to phase space constraints, so-called non-global logarithms (NGLs). In this paper, we show that NGLs can be factorized and resummed down to an unresolved infrared scale by making sufficiently many measurements on a jet or other restricted phase space region. Resummation is accomplished by renormalization group evolution of the objects in the factorization theorem and anomalous dimensions can be calculated to any perturbative accuracy and with any number of colors. To connect with the NGLs of more inclusive measurements, we present a novel perturbative expansion which is controlled by the volume of the allowed phase space for unresolved emissions. Arbitrary accuracy can be obtained by making more and more measurements so to resolve lower and lower scales. We find that even a minimal number of measurements produces agreement with Monte Carlo methods for leading-logarithmic resummation of NGLs at the sub-percent level over the full dynamical range relevant for the Large Hadron Collider. Here, we also discuss other applications of our factorization theorem to soft jet dynamics and how to extend to higher-order accuracy.},

doi = {10.1007/JHEP09(2015)143},

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

number = 9,

volume = 2015,

place = {United States},

year = {2015},

month = {9}

}

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