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Drell-Yan process in pA collisions : Path-integral treatment of coherence effects

Goncalves, Victor P. LU ; Krelina, Michal; Nemchik, Jan and Pasechnik, Roman LU (2016) In Physical Review D - Particles, Fields, Gravitation and Cosmology 94(11).
Abstract

In this work, we investigate production of Drell-Yan (DY) pairs in proton-nucleus collisions in kinematic regions where the corresponding coherence length does not exceed the nuclear radius, RA, and the quantum coherence effects should be treated with special care. The results for the nucleus-to-nucleon production ratio available in the literature so far are usually based on the assumption of a very long coherence length (LCL) lc RA. Since the onset of coherence effects is controlled by the coherence length lc, we estimated its magnitude in various kinematic regions of the DY process and found that the LCL approximation should not be used at small and medium c.m. collision energies (s 200 GeV) as well as at large dilepton invariant... (More)

In this work, we investigate production of Drell-Yan (DY) pairs in proton-nucleus collisions in kinematic regions where the corresponding coherence length does not exceed the nuclear radius, RA, and the quantum coherence effects should be treated with special care. The results for the nucleus-to-nucleon production ratio available in the literature so far are usually based on the assumption of a very long coherence length (LCL) lc RA. Since the onset of coherence effects is controlled by the coherence length lc, we estimated its magnitude in various kinematic regions of the DY process and found that the LCL approximation should not be used at small and medium c.m. collision energies (s 200 GeV) as well as at large dilepton invariant masses. In order to obtain realistic predictions, we computed for the first time the DY cross section using the generalized color dipole approach based on the rigorous Green function formalism, which naturally incorporates the color transparency and quantum coherence effects and hence allows us to estimate the nuclear shadowing with no restrictions on the CL. In addition to the shadowing effect, we studied a complementary effect of initial state interactions (ISI) that causes an additional suppression at large values of the Feynman variable. Numerical results for the nuclear modification factor accounting for the ISI effect and the finite lc are compared to the data available from the fixed-target Fermi National Laboratory measurements and a good agreement has been found. Besides, we present new predictions for the nuclear suppression as a function of dilepton rapidity and invariant mass in the kinematic regions that can be probed by the RHIC collider as well as by the planned AFTER@LHC and LHCb fixed-target experiments.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review D - Particles, Fields, Gravitation and Cosmology
volume
94
issue
11
publisher
American Physical Society
external identifiers
  • scopus:85021671356
  • wos:000390273000001
ISSN
2470-0010
DOI
10.1103/PhysRevD.94.114009
language
English
LU publication?
yes
id
13e1c3cb-f28e-4943-86bb-6920a0ab3a0f
date added to LUP
2017-07-20 12:10:04
date last changed
2017-09-18 11:38:54
@article{13e1c3cb-f28e-4943-86bb-6920a0ab3a0f,
  abstract     = {<p>In this work, we investigate production of Drell-Yan (DY) pairs in proton-nucleus collisions in kinematic regions where the corresponding coherence length does not exceed the nuclear radius, RA, and the quantum coherence effects should be treated with special care. The results for the nucleus-to-nucleon production ratio available in the literature so far are usually based on the assumption of a very long coherence length (LCL) lc RA. Since the onset of coherence effects is controlled by the coherence length lc, we estimated its magnitude in various kinematic regions of the DY process and found that the LCL approximation should not be used at small and medium c.m. collision energies (s 200 GeV) as well as at large dilepton invariant masses. In order to obtain realistic predictions, we computed for the first time the DY cross section using the generalized color dipole approach based on the rigorous Green function formalism, which naturally incorporates the color transparency and quantum coherence effects and hence allows us to estimate the nuclear shadowing with no restrictions on the CL. In addition to the shadowing effect, we studied a complementary effect of initial state interactions (ISI) that causes an additional suppression at large values of the Feynman variable. Numerical results for the nuclear modification factor accounting for the ISI effect and the finite lc are compared to the data available from the fixed-target Fermi National Laboratory measurements and a good agreement has been found. Besides, we present new predictions for the nuclear suppression as a function of dilepton rapidity and invariant mass in the kinematic regions that can be probed by the RHIC collider as well as by the planned AFTER@LHC and LHCb fixed-target experiments.</p>},
  articleno    = {114009},
  author       = {Goncalves, Victor P. and Krelina, Michal and Nemchik, Jan and Pasechnik, Roman},
  issn         = {2470-0010},
  language     = {eng},
  month        = {12},
  number       = {11},
  publisher    = {American Physical Society},
  series       = {Physical Review D - Particles, Fields, Gravitation and Cosmology},
  title        = {Drell-Yan process in pA collisions : Path-integral treatment of coherence effects},
  url          = {http://dx.doi.org/10.1103/PhysRevD.94.114009},
  volume       = {94},
  year         = {2016},
}