Dissecting Soft Radiation with Factorization
An essential part of high-energy hadronic collisions is the soft hadronic activity that underlies the primary hard interaction. It includes soft radiation from the primary hard partons, secondary multiple parton interactions (MPI), and factorization-violating effects. The invariant mass spectrum of...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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American Physical Society
2015
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| Online Access: | http://hdl.handle.net/1721.1/95837 https://orcid.org/0000-0003-0248-0979 |
| _version_ | 1811092585529212928 |
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| author | Tackmann, Frank J. Waalewijn, Wouter J. Stewart, Iain |
| author2 | Massachusetts Institute of Technology. Center for Theoretical Physics |
| author_facet | Massachusetts Institute of Technology. Center for Theoretical Physics Tackmann, Frank J. Waalewijn, Wouter J. Stewart, Iain |
| author_sort | Tackmann, Frank J. |
| collection | MIT |
| description | An essential part of high-energy hadronic collisions is the soft hadronic activity that underlies the primary hard interaction. It includes soft radiation from the primary hard partons, secondary multiple parton interactions (MPI), and factorization-violating effects. The invariant mass spectrum of the leading jet in Z+jet and H+jet events is directly sensitive to these effects, and we use a QCD factorization theorem to predict its dependence on the jet radius R, jet p[subscript T], jet rapidity, and partonic process for both the perturbative and nonperturbative components of primary soft radiation. We prove that the nonperturbative contributions involve only odd powers of R, and the linear R term is universal for quark and gluon jets. The hadronization model in Pythia8 agrees well with these properties. The perturbative soft initial state radiation (ISR) has a contribution that depends on the jet area in the same way as the underlying event, but this degeneracy is broken by dependence on the jet p[subscript T]. The size of this soft ISR contribution is proportional to the color state of the initial partons, yielding the same positive contribution for gg→Hg and gq→Zq, but a negative interference contribution for q[bar over q] →Zg. Hence, measuring these dependencies allows one to separate hadronization, soft ISR, and MPI contributions in the data. |
| first_indexed | 2024-09-23T15:20:33Z |
| format | Article |
| id | mit-1721.1/95837 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T15:20:33Z |
| publishDate | 2015 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | mit-1721.1/958372022-09-29T14:19:42Z Dissecting Soft Radiation with Factorization Tackmann, Frank J. Waalewijn, Wouter J. Stewart, Iain Massachusetts Institute of Technology. Center for Theoretical Physics Massachusetts Institute of Technology. Department of Physics Stewart, Iain An essential part of high-energy hadronic collisions is the soft hadronic activity that underlies the primary hard interaction. It includes soft radiation from the primary hard partons, secondary multiple parton interactions (MPI), and factorization-violating effects. The invariant mass spectrum of the leading jet in Z+jet and H+jet events is directly sensitive to these effects, and we use a QCD factorization theorem to predict its dependence on the jet radius R, jet p[subscript T], jet rapidity, and partonic process for both the perturbative and nonperturbative components of primary soft radiation. We prove that the nonperturbative contributions involve only odd powers of R, and the linear R term is universal for quark and gluon jets. The hadronization model in Pythia8 agrees well with these properties. The perturbative soft initial state radiation (ISR) has a contribution that depends on the jet area in the same way as the underlying event, but this degeneracy is broken by dependence on the jet p[subscript T]. The size of this soft ISR contribution is proportional to the color state of the initial partons, yielding the same positive contribution for gg→Hg and gq→Zq, but a negative interference contribution for q[bar over q] →Zg. Hence, measuring these dependencies allows one to separate hadronization, soft ISR, and MPI contributions in the data. United States. Dept. of Energy. Office of Science (Office of Nuclear Physics. Grant DE-SC0011090) German Research Foundation (Emmy-Noether Grant TA 867/1-1) Seventh Framework Programme (European Commission) (Marie Curie International Fellowship. PIIF-GA-2012-328913) 2015-03-05T15:23:49Z 2015-03-05T15:23:49Z 2015-03 2014-06 2015-03-04T23:00:02Z Article http://purl.org/eprint/type/JournalArticle 0031-9007 1079-7114 http://hdl.handle.net/1721.1/95837 Stewart, Iain W., Frank J. Tackmann, and Wouter J. Waalewijn. “Dissecting Soft Radiation with Factorization.” Physical Review Letters 114.9 (2015). © 2015 American Physical Society https://orcid.org/0000-0003-0248-0979 en http://dx.doi.org/10.1103/PhysRevLett.114.092001 Physical Review Letters Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. American Physical Society application/pdf American Physical Society American Physical Society |
| spellingShingle | Tackmann, Frank J. Waalewijn, Wouter J. Stewart, Iain Dissecting Soft Radiation with Factorization |
| title | Dissecting Soft Radiation with Factorization |
| title_full | Dissecting Soft Radiation with Factorization |
| title_fullStr | Dissecting Soft Radiation with Factorization |
| title_full_unstemmed | Dissecting Soft Radiation with Factorization |
| title_short | Dissecting Soft Radiation with Factorization |
| title_sort | dissecting soft radiation with factorization |
| url | http://hdl.handle.net/1721.1/95837 https://orcid.org/0000-0003-0248-0979 |
| work_keys_str_mv | AT tackmannfrankj dissectingsoftradiationwithfactorization AT waalewijnwouterj dissectingsoftradiationwithfactorization AT stewartiain dissectingsoftradiationwithfactorization |