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Title: Collectivity from interference

Abstract

In hadronic collisions, interference between different production channels affects momentum distributions of multi-particle final states. As this QCD interference does not depend on the strong coupling constant α s , it is part of the no-interaction baseline that needs to be controlled prior to searching for other manifestations of collective dynamics, e.g., in the analysis of azimuthal anisostropy coefficients v n at the LHC. Here, we introduce a model that is based on the QCD theory of multi-parton interactions and that allows one to study interference effects in the production of m particles in hadronic collisions with N parton-parton interactions (“sources”). In an expansion in powers of 1/( N c 2 – 1) and to leading order in the number of sources N, we calculate interference effects in the m-particle spectra and we determine from them the second and fourth order cumulant momentum anisotropies v n {2} and v n {4}. Without invoking any azimuthal asymmetry and any density dependent non-linear dynamics in the incoming state, and without invoking any interaction in the final state, we find that QCD interference alone can give rise to values for v n {2} and v n {4}, n even, that persist unattenuated formore » increasing number of sources, that may increase with increasing multiplicity and that agree with measurements in proton-proton (pp) collisions in terms of the order of magnitude of the signal and the approximate shape of the transverse momentum dependence. We further find that the non-abelian features of QCD interference can give rise to odd harmonic anisotropies. These findings indicate that the no-interaction baseline including QCD interference effects can make a sizeable if not dominant contribution to the measured v n coefficients in pp collisions. Prospects for analyzing QCD interference contributions further and their possible relevance for proton-nucleus and nucleus-nucleus collisions are discussed shortly.« less

Authors:
 [1];  [2];  [3];  [4]
  1. Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Physics
  2. Univ. of Sao Paulo, Sao Paulo (Brazil). Dept. of Applied Mathematics
  3. Pennsylvania State Univ., University Park, PA (United States). Dept of Physics
  4. European Organization for Nuclear Research (CERN), Geneva (Switzerland). Theoretical Physics Dept.
Publication Date:
Research Org.:
Pennsylvania State Univ., University Park, PA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1507416
Grant/Contract Number:  
FG02-93ER40771
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: 2017; Journal Issue: 12; Journal ID: ISSN 1029-8479
Publisher:
Springer Berlin
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Heavy Ion Phenomenology

Citation Formats

Blok, Boris, Jäkel, Christian D., Strikman, Mark, and Wiedemann, Urs Achim. Collectivity from interference. United States: N. p., 2017. Web. doi:10.1007/jhep12(2017)074.
Blok, Boris, Jäkel, Christian D., Strikman, Mark, & Wiedemann, Urs Achim. Collectivity from interference. United States. doi:10.1007/jhep12(2017)074.
Blok, Boris, Jäkel, Christian D., Strikman, Mark, and Wiedemann, Urs Achim. Thu . "Collectivity from interference". United States. doi:10.1007/jhep12(2017)074. https://www.osti.gov/servlets/purl/1507416.
@article{osti_1507416,
title = {Collectivity from interference},
author = {Blok, Boris and Jäkel, Christian D. and Strikman, Mark and Wiedemann, Urs Achim},
abstractNote = {In hadronic collisions, interference between different production channels affects momentum distributions of multi-particle final states. As this QCD interference does not depend on the strong coupling constant α s , it is part of the no-interaction baseline that needs to be controlled prior to searching for other manifestations of collective dynamics, e.g., in the analysis of azimuthal anisostropy coefficients v n at the LHC. Here, we introduce a model that is based on the QCD theory of multi-parton interactions and that allows one to study interference effects in the production of m particles in hadronic collisions with N parton-parton interactions (“sources”). In an expansion in powers of 1/(Nc2 – 1) and to leading order in the number of sources N, we calculate interference effects in the m-particle spectra and we determine from them the second and fourth order cumulant momentum anisotropies v n {2} and v n {4}. Without invoking any azimuthal asymmetry and any density dependent non-linear dynamics in the incoming state, and without invoking any interaction in the final state, we find that QCD interference alone can give rise to values for v n {2} and v n {4}, n even, that persist unattenuated for increasing number of sources, that may increase with increasing multiplicity and that agree with measurements in proton-proton (pp) collisions in terms of the order of magnitude of the signal and the approximate shape of the transverse momentum dependence. We further find that the non-abelian features of QCD interference can give rise to odd harmonic anisotropies. These findings indicate that the no-interaction baseline including QCD interference effects can make a sizeable if not dominant contribution to the measured v n coefficients in pp collisions. Prospects for analyzing QCD interference contributions further and their possible relevance for proton-nucleus and nucleus-nucleus collisions are discussed shortly.},
doi = {10.1007/jhep12(2017)074},
journal = {Journal of High Energy Physics (Online)},
number = 12,
volume = 2017,
place = {United States},
year = {2017},
month = {12}
}

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