Advertisement

Event-by-event fluctuations in the medium-induced jet evolution

  • Miguel A. Escobedo
  • Edmond Iancu
Open Access
Regular Article - Theoretical Physics

Abstract

We develop the event-by-event picture of the gluon distribution produced via medium-induced gluon branching by an energetic jet which propagates through a dense QCD medium. A typical event is characterized by the production of a large number of soft gluons which propagate at large angles with respect to the jet axis and which collectively carry a substantial amount of energy. By explicitly computing 2-gluon correlations, we demonstrate the existence of large event-by-event fluctuations, which reflect the stochastic nature of the branching process. For the two quantities that we have investigated — the energy loss at large angles and the soft gluon multiplicity —, the dispersion is parametrically as large as the respective expectation value. We identify interesting scaling laws, which suggest that the multiplicity distribution should exhibit KNO (Koba-Nielsen-Olesen) scaling. A similar scaling is known to hold for a jet branching in the vacuum, but the medium-induced distribution is found to be considerably broader. We predict that event-by-event measurements of the di-jet asymmetry in Pb+Pb collisions at the LHC should observe large fluctuations in the number of soft hadrons propagating at large angles and also in the total energy carried by these hadrons.

Keywords

Perturbative QCD Resummation Quark-Gluon Plasma 

Notes

Open Access

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.

References

  1. [1]
    ATLAS collaboration, Observation of a Centrality-Dependent Dijet Asymmetry in Lead-Lead Collisions at \( \sqrt{s_{N\;N}}=2.77 \) TeV with the ATLAS Detector at the LHC, Phys. Rev. Lett. 105 (2010) 252303 [arXiv:1011.6182] [INSPIRE].
  2. [2]
    CMS collaboration, Observation and studies of jet quenching in PbPb collisions at nucleon-nucleon center-of-mass energy = 2.76 TeV, Phys. Rev. C 84 (2011) 024906 [arXiv:1102.1957] [INSPIRE].
  3. [3]
    CMS collaboration, Jet momentum dependence of jet quenching in PbPb collisions at \( \sqrt{s_{N\;N}}=2.76 \) TeV, Phys. Lett. B 712 (2012) 176 [arXiv:1202.5022] [INSPIRE].
  4. [4]
    ATLAS collaboration, Measurement of the jet radius and transverse momentum dependence of inclusive jet suppression in lead-lead collisions at \( \sqrt{s_{N\;N}}=2.76 \) TeV with the ATLAS detector, Phys. Lett. B 719 (2013) 220 [arXiv:1208.1967] [INSPIRE].
  5. [5]
    CMS collaboration, Modification of jet shapes in PbPb collisions at \( \sqrt{s_{N\;N}}=2.76 \) TeV, Phys. Lett. B 730 (2014) 243 [arXiv:1310.0878] [INSPIRE].
  6. [6]
    CMS collaboration, Measurement of jet fragmentation in PbPb and pp collisions at \( \sqrt{s_{N\;N}}=2.76 \) TeV, Phys. Rev. C 90 (2014) 024908 [arXiv:1406.0932] [INSPIRE].
  7. [7]
    ATLAS collaboration, Measurement of inclusive jet charged-particle fragmentation functions in Pb+Pb collisions at \( \sqrt{s_{N\;N}}=2.76 \) TeV with the ATLAS detector, Phys. Lett. B 739 (2014) 320 [arXiv:1406.2979] [INSPIRE].
  8. [8]
    CMS collaboration, Measurement of transverse momentum relative to dijet systems in PbPb and pp collisions at \( \sqrt{s_{\mathrm{NN}}}=2.76 \) TeV, JHEP 01 (2016) 006 [arXiv:1509.09029] [INSPIRE].
  9. [9]
    CMS collaboration, Correlations between jets and charged particles in PbPb and pp collisions at \( \sqrt{s_{\mathrm{NN}}}=2.76 \) TeV, JHEP 02 (2016) 156 [arXiv:1601.00079] [INSPIRE].
  10. [10]
    J. Casalderrey-Solana, J.G. Milhano and U.A. Wiedemann, Jet Quenching via Jet Collimation, J. Phys. G 38 (2011) 035006 [arXiv:1012.0745] [INSPIRE].ADSCrossRefGoogle Scholar
  11. [11]
    J.-P. Blaizot, E. Iancu and Y. Mehtar-Tani, Medium-induced QCD cascade: democratic branching and wave turbulence, Phys. Rev. Lett. 111 (2013) 052001 [arXiv:1301.6102] [INSPIRE].ADSCrossRefGoogle Scholar
  12. [12]
    R. Baier, Y.L. Dokshitzer, A.H. Mueller, S. Peigne and D. Schiff, Radiative energy loss of high-energy quarks and gluons in a finite volume quark-gluon plasma, Nucl. Phys. B 483 (1997) 291 [hep-ph/9607355] [INSPIRE].
  13. [13]
    R. Baier, Y.L. Dokshitzer, A.H. Mueller, S. Peigne and D. Schiff, Radiative energy loss and p T broadening of high-energy partons in nuclei, Nucl. Phys. B 484 (1997) 265 [hep-ph/9608322] [INSPIRE].
  14. [14]
    B.G. Zakharov, Fully quantum treatment of the Landau-Pomeranchuk-Migdal effect in QED and QCD, JETP Lett. 63 (1996) 952 [hep-ph/9607440] [INSPIRE].
  15. [15]
    B.G. Zakharov, Radiative energy loss of high-energy quarks in finite size nuclear matter and quark-gluon plasma, JETP Lett. 65 (1997) 615 [hep-ph/9704255] [INSPIRE].
  16. [16]
    R. Baier, Y.L. Dokshitzer, A.H. Mueller and D. Schiff, Medium induced radiative energy loss: Equivalence between the BDMPS and Zakharov formalisms, Nucl. Phys. B 531 (1998) 403 [hep-ph/9804212] [INSPIRE].
  17. [17]
    U.A. Wiedemann, Gluon radiation off hard quarks in a nuclear environment: Opacity expansion, Nucl. Phys. B 588 (2000) 303 [hep-ph/0005129] [INSPIRE].
  18. [18]
    U.A. Wiedemann, Jet quenching versus jet enhancement: A Quantitative study of the BDMPS-Z gluon radiation spectrum, Nucl. Phys. A 690 (2001) 731 [hep-ph/0008241] [INSPIRE].
  19. [19]
    P.B. Arnold, G.D. Moore and L.G. Yaffe, Photon emission from ultrarelativistic plasmas, JHEP 11 (2001) 057 [hep-ph/0109064] [INSPIRE].
  20. [20]
    P.B. Arnold, G.D. Moore and L.G. Yaffe, Photon emission from quark gluon plasma: Complete leading order results, JHEP 12 (2001) 009 [hep-ph/0111107] [INSPIRE].
  21. [21]
    P.B. Arnold, G.D. Moore and L.G. Yaffe, Photon and gluon emission in relativistic plasmas, JHEP 06 (2002) 030 [hep-ph/0204343] [INSPIRE].
  22. [22]
    J.-P. Blaizot, F. Dominguez, E. Iancu and Y. Mehtar-Tani, Medium-induced gluon branching, JHEP 01 (2013) 143 [arXiv:1209.4585] [INSPIRE].ADSCrossRefGoogle Scholar
  23. [23]
    J.-P. Blaizot, F. Dominguez, E. Iancu and Y. Mehtar-Tani, Probabilistic picture for medium-induced jet evolution, JHEP 06 (2014) 075 [arXiv:1311.5823] [INSPIRE].ADSCrossRefGoogle Scholar
  24. [24]
    L. Apolinário, N. Armesto, J.G. Milhano and C.A. Salgado, Medium-induced gluon radiation and colour decoherence beyond the soft approximation, JHEP 02 (2015) 119 [arXiv:1407.0599] [INSPIRE].ADSCrossRefGoogle Scholar
  25. [25]
    R. Baier, A.H. Mueller, D. Schiff and D.T. Son, ’Bottom up’ thermalization in heavy ion collisions, Phys. Lett. B 502 (2001) 51 [hep-ph/0009237] [INSPIRE].
  26. [26]
    R. Baier, Y.L. Dokshitzer, A.H. Mueller and D. Schiff, Quenching of hadron spectra in media, JHEP 09 (2001) 033 [hep-ph/0106347] [INSPIRE].
  27. [27]
    P.B. Arnold, G.D. Moore and L.G. Yaffe, Effective kinetic theory for high temperature gauge theories, JHEP 01 (2003) 030 [hep-ph/0209353] [INSPIRE].
  28. [28]
    S. Jeon and G.D. Moore, Energy loss of leading partons in a thermal QCD medium, Phys. Rev. C 71 (2005) 034901 [hep-ph/0309332] [INSPIRE].
  29. [29]
    B. Schenke, C. Gale and S. Jeon, MARTINI: An Event generator for relativistic heavy-ion collisions, Phys. Rev. C 80 (2009) 054913 [arXiv:0909.2037] [INSPIRE].ADSGoogle Scholar
  30. [30]
    Y. Mehtar-Tani, C.A. Salgado and K. Tywoniuk, Anti-angular ordering of gluon radiation in QCD media, Phys. Rev. Lett. 106 (2011) 122002 [arXiv:1009.2965] [INSPIRE].ADSCrossRefGoogle Scholar
  31. [31]
    Y. Mehtar-Tani, C.A. Salgado and K. Tywoniuk, Jets in QCD Media: From Color Coherence to Decoherence, Phys. Lett. B 707 (2012) 156 [arXiv:1102.4317] [INSPIRE].ADSCrossRefGoogle Scholar
  32. [32]
    J. Casalderrey-Solana and E. Iancu, Interference effects in medium-induced gluon radiation, JHEP 08 (2011) 015 [arXiv:1105.1760] [INSPIRE].ADSCrossRefGoogle Scholar
  33. [33]
    J. Casalderrey-Solana, Y. Mehtar-Tani, C.A. Salgado and K. Tywoniuk, New picture of jet quenching dictated by color coherence, Phys. Lett. B 725 (2013) 357 [arXiv:1210.7765] [INSPIRE].ADSCrossRefGoogle Scholar
  34. [34]
    A. Kurkela and U.A. Wiedemann, Picturing perturbative parton cascades in QCD matter, Phys. Lett. B 740 (2015) 172 [arXiv:1407.0293] [INSPIRE].ADSCrossRefGoogle Scholar
  35. [35]
    J. Casalderrey-Solana, D. Pablos and K. Tywoniuk, Jet formation and interference in a thin QCD medium, arXiv:1512.07561 [INSPIRE].
  36. [36]
    J.-P. Blaizot and Y. Mehtar-Tani, Jet Structure in Heavy Ion Collisions, Int. J. Mod. Phys. E 24 (2015) 1530012 [arXiv:1503.05958] [INSPIRE].ADSCrossRefGoogle Scholar
  37. [37]
    L. Fister and E. Iancu, Medium-induced jet evolution: wave turbulence and energy loss, JHEP 03 (2015) 082 [arXiv:1409.2010] [INSPIRE].CrossRefGoogle Scholar
  38. [38]
    J.-P. Blaizot and Y. Mehtar-Tani, Energy flow along the medium-induced parton cascade, Annals Phys. 368 (2016) 148 [arXiv:1501.03443] [INSPIRE].ADSMathSciNetCrossRefGoogle Scholar
  39. [39]
    E. Iancu, Di-jet asymmetry and wave turbulence, Nucl. Phys. A 932 (2014) 197 [arXiv:1404.4566] [INSPIRE].ADSCrossRefGoogle Scholar
  40. [40]
    J.-P. Blaizot, Y. Mehtar-Tani and M.A.C. Torres, Angular structure of the in-medium QCD cascade, Phys. Rev. Lett. 114 (2015) 222002 [arXiv:1407.0326] [INSPIRE].ADSCrossRefGoogle Scholar
  41. [41]
    J.-P. Blaizot, L. Fister and Y. Mehtar-Tani, Angular distribution of medium-induced QCD cascades, Nucl. Phys. A 940 (2015) 67 [arXiv:1409.6202] [INSPIRE].ADSCrossRefGoogle Scholar
  42. [42]
    E. Iancu and B. Wu, Thermalization of mini-jets in a quark-gluon plasma, JHEP 10 (2015) 155 [arXiv:1506.07871] [INSPIRE].ADSCrossRefGoogle Scholar
  43. [43]
    Z. Koba, H.B. Nielsen and P. Olesen, Scaling of multiplicity distributions in high-energy hadron collisions, Nucl. Phys. B 40 (1972) 317 [INSPIRE].ADSCrossRefGoogle Scholar
  44. [44]
    Y.L. Dokshitzer, V.A. Khoze, A.H. Mueller and S.I. Troian, Basics of perturbative QCD, Editions Frontieres, Gif-sur-Yvette France (1991).Google Scholar
  45. [45]
    J.G. Milhano and K.C. Zapp, Origins of the di-jet asymmetry in heavy ion collisions, arXiv:1512.08107 [INSPIRE].
  46. [46]
    V. Zakharov, V. Lvov, and G. Falkovich, Kolmogorov spectra of turbulence, Volume 1, Springer-Verlag, Berlin Germany (1992).CrossRefGoogle Scholar
  47. [47]
    S. Nazarenko, Wave Turbulence, Springer-Verlag, Berlin Germany (2011).CrossRefMATHGoogle Scholar
  48. [48]
    K.C. Zapp, F. Krauss and U.A. Wiedemann, A perturbative framework for jet quenching, JHEP 03 (2013) 080 [arXiv:1212.1599] [INSPIRE].ADSCrossRefGoogle Scholar

Copyright information

© The Author(s) 2016

Authors and Affiliations

  1. 1.Institut de physique théoriqueUniversité Paris Saclay, CNRS, CEAGif-sur-YvetteFrance

Personalised recommendations