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Title: Lensing mechanism meets small- x physics: Single transverse spin asymmetry in p + p and p + A collisions

Abstract

We calculate the single transverse spin asymmetry (STSA) in polarized proton-proton (p+p) and polarized proton-nucleus (p+A) collisions (AN) generated by a partonic lensing mechanism. The polarized proton is considered in the quark-diquark model while its interaction with the unpolarized target is calculated using the small-x/saturation approach, which includes multiple rescatterings and small-x evolution. The phase required for the asymmetry is caused by a final-state gluon exchange between the quark and diquark, as is standard in the lensing mechanism of Brodsky, Hwang and Schmidt. Our calculation combines the lensing mechanism with small-x physics in the saturation framework. The expression we obtain for the asymmetry AN of the produced quarks has the following properties: (i) The asymmetry is generated by the dominant elastic scattering contribution and 1/$$N^{2}_{c}$$ suppressed inelastic contribution (with Nc the number of quark colors); (ii) The asymmetry grows or oscillates with the produced quark's transverse momentum pT until the momentum reaches the saturation scale Qs, and then only falls off as 1/pT for larger momenta; (iii) The asymmetry decreases with increasing atomic number A of the target for pT below or near Qs, but is independent of A for pT significantly above Qs. We discuss how these properties may be qualitatively consistent with the data on AN published by the PHENIX collaboration and with the preliminary data on AN reported by the STAR collaboration.

Authors:
ORCiD logo;
Publication Date:
Research Org.:
The Ohio State Univ., Columbus, OH (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP)
OSTI Identifier:
1638419
Alternate Identifier(s):
OSTI ID: 1770386
Grant/Contract Number:  
SC0004286
Resource Type:
Published Article
Journal Name:
Physical Review D
Additional Journal Information:
Journal Name: Physical Review D Journal Volume: 102 Journal Issue: 1; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Kovchegov, Yuri V., and Santiago, M. Gabriel. Lensing mechanism meets small- x physics: Single transverse spin asymmetry in p ↑ + p and p ↑ + A collisions. United States: N. p., 2020. Web. https://doi.org/10.1103/PhysRevD.102.014022.
Kovchegov, Yuri V., & Santiago, M. Gabriel. Lensing mechanism meets small- x physics: Single transverse spin asymmetry in p ↑ + p and p ↑ + A collisions. United States. https://doi.org/10.1103/PhysRevD.102.014022
Kovchegov, Yuri V., and Santiago, M. Gabriel. Tue . "Lensing mechanism meets small- x physics: Single transverse spin asymmetry in p ↑ + p and p ↑ + A collisions". United States. https://doi.org/10.1103/PhysRevD.102.014022.
@article{osti_1638419,
title = {Lensing mechanism meets small- x physics: Single transverse spin asymmetry in p ↑ + p and p ↑ + A collisions},
author = {Kovchegov, Yuri V. and Santiago, M. Gabriel},
abstractNote = {We calculate the single transverse spin asymmetry (STSA) in polarized proton-proton (p↑+p) and polarized proton-nucleus (p↑+A) collisions (AN) generated by a partonic lensing mechanism. The polarized proton is considered in the quark-diquark model while its interaction with the unpolarized target is calculated using the small-x/saturation approach, which includes multiple rescatterings and small-x evolution. The phase required for the asymmetry is caused by a final-state gluon exchange between the quark and diquark, as is standard in the lensing mechanism of Brodsky, Hwang and Schmidt. Our calculation combines the lensing mechanism with small-x physics in the saturation framework. The expression we obtain for the asymmetry AN of the produced quarks has the following properties: (i) The asymmetry is generated by the dominant elastic scattering contribution and 1/$N^{2}_{c}$ suppressed inelastic contribution (with Nc the number of quark colors); (ii) The asymmetry grows or oscillates with the produced quark's transverse momentum pT until the momentum reaches the saturation scale Qs, and then only falls off as 1/pT for larger momenta; (iii) The asymmetry decreases with increasing atomic number A of the target for pT below or near Qs, but is independent of A for pT significantly above Qs. We discuss how these properties may be qualitatively consistent with the data on AN published by the PHENIX collaboration and with the preliminary data on AN reported by the STAR collaboration.},
doi = {10.1103/PhysRevD.102.014022},
journal = {Physical Review D},
number = 1,
volume = 102,
place = {United States},
year = {2020},
month = {7}
}

Journal Article:
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https://doi.org/10.1103/PhysRevD.102.014022

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Works referenced in this record:

Transverse single spin asymmetries at small x and the anomalous magnetic moment
journal, April 2014


Small- x Asymptotics of the Quark Helicity Distribution
journal, January 2017


The spin dependent odderon in the diquark model
journal, September 2016


Nonlinear QCD meets data: A global analysis of lepton-proton scattering with running coupling Balitsky-Kovchegov evolution
journal, August 2009

  • Albacete, Javier L.; Armesto, Néstor; Milhano, José Guilherme
  • Physical Review D, Vol. 80, Issue 3
  • DOI: 10.1103/PhysRevD.80.034031

Leading-twist single-transverse-spin asymmetries: Drell–Yan and deep-inelastic scattering
journal, May 2002


Small-x asymptotics of the gluon helicity distribution
journal, October 2017

  • Kovchegov, Yuri V.; Pitonyak, Daniel; Sievert, Matthew D.
  • Journal of High Energy Physics, Vol. 2017, Issue 10
  • DOI: 10.1007/JHEP10(2017)198

Single-spin asymmetries in semi-inclusive deep inelastic scattering and Drell-Yan processes
journal, July 2013


The Color Glass Condensate
journal, November 2010


Production of q q ¯ pairs in proton-nucleus collisions at high energies
journal, September 2006


Evolution at small : The color glass condensate
journal, October 2005


Subleading- corrections in non-linear small-x evolution
journal, May 2009


Cronin effect and high- p T suppression in pA collisions
journal, November 2003


Relations between generalized and transverse momentum dependent parton distributions
journal, August 2007


Distribution of Linearly Polarized Gluons and Elliptic Azimuthal Anisotropy in Deep Inelastic Scattering Dijet Production at High Energy
journal, December 2015


New mechanism for generating a single transverse spin asymmetry
journal, August 2012


Quark jets scattering from a gluon field: From saturation to high p t
journal, January 2019


Sivers function in the quasiclassical approximation
journal, March 2014


Helicity evolution at small x : Flavor singlet and nonsinglet observables
journal, January 2017


Quantum structure of the non-Abelian Weizsäcker-Williams field for a very large nucleus
journal, May 1997


Sub-eikonal corrections to scattering amplitudes at high energy
journal, January 2019


Hard-scattering scaling laws for single-spin production asymmetries
journal, January 1991


Single-spin production asymmetries from the hard scattering of pointlike constituents
journal, January 1990


Gluon TMD in particle production from low to moderate x
journal, June 2016


Single transverse spin asymmetries
journal, October 1991


Orbital angular momentum at small x
journal, March 2019


Single spin asymmetry scaling in the forward rapidity region at RHIC
journal, August 2011


Nonlinear gluon evolution in the color glass condensate: II
journal, May 2002


Helicity-dependent generalization of the JIMWLK evolution
journal, December 2019


The renormalization group equation for the color glass condensate
journal, June 2001


Proton spin structure at small-x
journal, October 2019


Nonlinear gluon evolution in the color glass condensate: I
journal, September 2001


Comparison of spin asymmetries and cross sections in π0 production by 200 GeV polarized antiprotons and protons
journal, May 1991


The saturation scale and its x-dependence from Λ polarization studies
journal, January 2009


Saturation effects in deep inelastic scattering at low Q 2 and its implications on diffraction
journal, November 1998


Wilson renormalization group for low x physics: Gluon evolution at finite parton density
journal, November 1998


Transverse single spin asymmetry in Drell-Yan production in polarized pA collisions
journal, July 2015


Chromodynamic lensing and transverse single spin asymmetries
journal, April 2004


AAMQS: A non-linear QCD analysis of new HERA data at small-x including heavy quarks
journal, July 2011

  • Albacete, Javier L.; Armesto, Néstor; Milhano, José Guilherme
  • The European Physical Journal C, Vol. 71, Issue 7
  • DOI: 10.1140/epjc/s10052-011-1705-3

Single transverse-spin asymmetries in forward pion production at high energy: Incorporating small- x effects in the target
journal, October 2006


Gluon production in current-nucleus and nucleon-nucleus collisions in a quasi-classical approximation
journal, September 1998


Odderon in the color glass condensate
journal, October 2005


Forward Neutral-Pion Transverse Single-Spin Asymmetries in p + p Collisions at s = 200 GeV
journal, November 2008


QCD asymmetry and polarized hadron structure function measurement
journal, January 1985


Energy Dependence of the Cronin Effect from Nonlinear QCD Evolution
journal, February 2004


Gluon distribution functions for very large nuclei at small transverse momentum
journal, April 1994


Inclusive two-gluon and valence-quark-gluon production in DIS and p A collisions
journal, December 2004


Saturation physics and deuteron–gold collisions at RHIC
journal, January 2006


Single transverse-spin asymmetries in hadronic pion production
journal, November 1998


On the small-x evolution of the color quadrupole and the Weizsäcker–Williams gluon distribution
journal, November 2011


Next-to-next-to-eikonal corrections in the CGC
journal, January 2016

  • Altinoluk, Tolga; Armesto, Néstor; Beuf, Guillaume
  • Journal of High Energy Physics, Vol. 2016, Issue 1
  • DOI: 10.1007/JHEP01(2016)114

Intrinsic glue distribution at very small x
journal, May 1997

  • Jalilian-Marian, Jamal; Kovner, Alex; McLerran, Larry
  • Physical Review D, Vol. 55, Issue 9
  • DOI: 10.1103/PhysRevD.55.5414

Gluon saturation and initial conditions for relativistic heavy ion collisions
journal, May 2014


Transverse single spin asymmetry in direct photon production in polarized p A collisions
journal, August 2014


Small-x behavior and parton saturation: A QCD model
journal, April 1990


Saturation in diffractive deep inelastic scattering
journal, November 1999


Initial-state interactions and single-spin asymmetries in Drell–Yan processes
journal, October 2002


Operator expansion for high-energy scattering
journal, March 1996


Single spin asymmetry in forward p A collisions. II. Fragmentation contribution
journal, January 2017


Wilson renormalization group for low x physics: Towards the high density regime
journal, November 1998


Transverse Quark Polarization in Large- p T Reactions, e + e Jets, and Leptoproduction: A Test of Quantum Chromodynamics
journal, December 1978


Green’s function in the color field of a large nucleus
journal, August 1994


Fragmentation contribution to the transverse single-spin asymmetry in proton–proton collisions
journal, June 2013


Universality of unintegrated gluon distributions at small x
journal, May 2011


Diffractive structure function in a quasiclassical approximation
journal, August 1999


Next-to-eikonal corrections in the CGC: gluon production and spin asymmetries in pA collisions
journal, July 2014

  • Altinoluk, Tolga; Armesto, Néstor; Beuf, Guillaume
  • Journal of High Energy Physics, Vol. 2014, Issue 7
  • DOI: 10.1007/JHEP07(2014)068

Parton saturation and Npart scaling of semi-hard processes in QCD
journal, May 2003


Final-state interactions and single-spin asymmetries in semi-inclusive deep inelastic scattering
journal, March 2002


Single Spin Asymmetries from a Single Wilson Loop
journal, March 2016


Inclusive jet production off the nucleus in the perturbative QCD with Nc→∞
journal, June 2000


Analyzing power in inclusive π+ and π− production at high xF with a 200 GeV polarized proton beam
journal, August 1991


Calculating TMDs of a large nucleus: Quasi-classical approximation and quantum evolution
journal, February 2016


Baryon stopping and valence quark distribution at small x
journal, January 2004


Exclusive processes in perturbative quantum chromodynamics
journal, November 1980


Gluon orbital angular momentum at small x
journal, June 2017


Small- x F 2 structure function of a nucleus including multiple Pomeron exchanges
journal, June 1999


Quantum chromodynamics and other field theories on the light cone
journal, August 1998


Large p_T Forward Transverse Single Spin Asymmetries of π^0 Mesons at √s= 200 and 500 GeV from STAR.
conference, December 2013

  • Heppelmann, Steven
  • Proceedings of XXI International Workshop on Deep-Inelastic Scattering and Related Subjects — PoS(DIS 2013)
  • DOI: 10.22323/1.191.0240

Unitarity at small Bjorken x
journal, June 2002


Small- x asymptotics of the quark helicity distribution: Analytic results
journal, September 2017


Inclusive gluon production in deep inelastic scattering at high parton density
journal, March 2002


Azimuthal and single spin asymmetries in hard scattering processes
journal, October 2008


Computing quark and gluon distribution functions for very large nuclei
journal, March 1994


Polarized hyperons from pA scattering in the gluon saturation regime
journal, March 2003


Unitarization of the BFKL Pomeron on a nucleus
journal, March 2000


Baryon stopping in proton–nucleus collisions
journal, January 2007


Valence quark transversity at small x
journal, March 2019


Two-gluon correlations in heavy–light ion collisions: Energy and geometry dependence, IR divergences, and <mml:math altimg="si1.gif" overflow="scroll" xmlns:xocs="http://www.elsevier.com/xml/xocs/dtd" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.elsevier.com/xml/ja/dtd" xmlns:ja="http://www.elsevier.com/xml/ja/dtd" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:tb="http://www.elsevier.com/xml/common/table/dtd" xmlns:sb="http://www.elsevier.com/xml/common/struct-bib/dtd" xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:cals="http://www.elsevier.com/xml/common/cals/dtd" xmlns:sa="http://www.elsevier.com/xml/common/struct-aff/dtd"><mml:msub><mml:mrow><mml:mi>k</mml:mi></mml:mrow><mml:mrow><mml:mi>T</mml:mi></mml:mrow></mml:msub></mml:math>-factorization
journal, May 2014


Single spin asymmetry in forward p A collisions
journal, September 2016


Gluon TMDs in Quarkonium Production
journal, January 2017


Single spin asymmetry in forward p A collisions: Phenomenology at RHIC
journal, May 2019


Small- x helicity evolution: An operator treatment
journal, March 2019


Rapidity evolution of gluon TMD from low to moderate x
journal, October 2015


Helicity evolution at small x
journal, January 2016

  • Kovchegov, Yuri V.; Pitonyak, Daniel; Sievert, Matthew D.
  • Journal of High Energy Physics, Vol. 2016, Issue 1
  • DOI: 10.1007/JHEP01(2016)072

Factorization and high-energy effective action
journal, June 1999