Spin physics through unpolarized processes

Lü, Zhun

doi:10.1007/s11467-015-0525-6

Cited by 6 publications

(4 citation statements)

References 150 publications

(245 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the last decade the angular coefficients were also measured in the p N Drell-Yan processes in both the fixed target mode [105,106] and collider mode [48,49]. The origin of large cos 2φ asymmetry-or the violation of the Lam-Tung relation-observed in Drell-Yan process has been studied extensively in literature [30,[50][51][52][53][54][55][56][107][108][109][110][111]. Here we will only consider the contribution from the coupling of two Boer-Mulders functions from each hadron, denoted by ν BM .…”

Section: B the Sivers Asymmetrymentioning

confidence: 99%

π-N Drell-Yan Process in TMD Factorization

Wang

Lü

2019

Advances in High Energy Physics

Self Cite

View full text Add to dashboard Cite

This article presents the review of the current understanding on the pion-nucleon Drell-Yan process from the point of view of the TMD factorization. Using the evolution formalism for the unpolarized and polarized TMD distributions developed recently, we provide the theoretical expression of the relevant physical observables, namely, the unpolarized cross section, the Sivers asymmetry, and the cos 2φ asymmetry contributed by the double Boer-Mulders effects. The corresponding phenomenology, particularly at the kinematical configuration of the COMPASS πN Drell-Yan facility, is displayed numerically.

show abstract

Section: B the Sivers Asymmetrymentioning

confidence: 99%

π-N Drell-Yan Process in TMD Factorization

Wang

Lü

2019

Advances in High Energy Physics

Self Cite

View full text Add to dashboard Cite

show abstract

“…The angular differential cross section for unpolarized Drell-Yan process has the following general form [3] 1 σ…”

Section: The Cos 2φ Azimuthal Asymmetry Contributed By the Boer-mulde...mentioning

confidence: 99%

“…INTRODUCTIONThe Boer-Mulders function is a transverse momentum dependent (TMD) parton distribution function (PDF) that describes the transverse-polarization asymmetry of quarks inside an unpolarized hadron [1,2]. Arising from the correlation between the quark transverse spin and the quark transverse momentum, the Boer-Mulders function manifests novel spin structure of hadrons [3]. For a while the very existence of the Boer-Mulders function was not as obvious.…”

mentioning

confidence: 99%

Boer-Mulders effect in the unpolarized pion induced Drell–Yan process at COMPASS within TMD factorization

2018

Self Cite

View full text Add to dashboard Cite

We investigate the theoretical framework of the cos 2φ azimuthal asymmetry contributed by the coupling of two Boer-Mulders functions in the dilepton production unpolarized πp Drell-Yan process by applying the transverse momentum dependent factorization at leading order. We adopt the model calculation results of the unpolarized distribution function f1 and Boer-Mulders function h ⊥ 1 of pion meson from the light-cone wave functions. We take into account the transverse momentum evolution effects for both the distribution functions of pion and proton by adopting the existed extraction of the nonperturbative Sudakov form factor for the pion and proton distribution functions. An approximate kernel is included to deal with the energy dependence of the Boer-Mulders function related twist-3 correlation function T (σ) q,F (x, x) needed in the calculation. We numerically estimate the Boer-Mulders asymmetry νBM as the functions of xp, xπ, xF and qT considering the kinematics at COMPASS Collaboration. 13.85.Qk, 13.88.+e I. INTRODUCTIONThe Boer-Mulders function is a transverse momentum dependent (TMD) parton distribution function (PDF) that describes the transverse-polarization asymmetry of quarks inside an unpolarized hadron [1,2]. Arising from the correlation between the quark transverse spin and the quark transverse momentum, the Boer-Mulders function manifests novel spin structure of hadrons [3]. For a while the very existence of the Boer-Mulders function was not as obvious. This is because, similar to its counterpart, the Sivers function, the Boer-Mulders function was thought to be forbidden by the time-reversal invariance of QCD [4]. For this reason, they are classified as T-odd distributions. However, model calculations incorporating gluon exchange between the struck quark and the spectator [5,6], together with a re-examination [7] on the time-reversal argument, show that T-odd distributions actually do not vanish. It was found that the gauge-links [7][8][9][10] in the operator definition of TMD distributions play an essential role for a nonzero Boer-Mulders function.As a chiral-odd distribution, the Boer-Mulders function has to be coupled with another chiral-odd distribution/fragmentation function to survive in a high energy scattering process. Two promising processes for accessing the Boer-Mulders function are the Drell-Yan and the semi-inclusive deep inelastic scattering (SIDIS) processes. In the former case, the corresponding observables are the cos 2φ azimuthal angular dependence of the final-state dilepton, which is originated by the convolution of two Boer-Mulders functions from each hadron. This effect was originally proposed by Boer [1] to explain the violation of the Lam-Tung relation observed in πN Drell-Yan process[11], a phenomenon which cannot be understood from purely perturbative QCD effects [12][13][14]. Similar asymmetry was also observed in the pd and pp Drell-Yan processes, and the corresponding data were applied to extract the proton Boer-Mulders function [15][16][17][18]. Besides the parmater...

show abstract

“…The Boer-Mulders function is a transverse momentum dependent (TMD) distribution function which describes the transversely polarization distribution of the quark inside an unpolarized hadron [1]. It has attracted a lot of attention because it manifests novel structure of hadron that encodes the correlation of quark transverse momentum and transverse spin [2]. It also brings new insights to QCD dynamics as a nonvanishing Boer-Mulders function requires gluon rescattering effect [3].…”

Section: Introductionmentioning

confidence: 99%

Boer-Mulders function of pion meson and $q_T$-weighted $\cos2ϕ$ asymmetry in the unpolarized $π^- p$ Drell-Yan at COMPASS

Wang,

2017

Preprint

Self Cite

View full text Add to dashboard Cite

We calculate the two leading-twist transverse momentum dependent distribution functions of the pion meson, the unpolarized distribution f1π(x, k 2 T ) and the Boer-Mulders function h ⊥ 1π (x, k 2 T ), using the pion wave functions derived from a light-cone approach. The evolution effect of the first kT -moment of the pion Boer-Mulders function is studied by employing an approximate evolution kernel. Using the model resulting distributions, we predict the transverse momentum weighted cos 2φ azimuthal asymmetry in the unpolarized π − p Drell-Yan process which can be measured at COMPASS in the near future.

show abstract

Spin physics through unpolarized processes

Cited by 6 publications

References 150 publications

π-N Drell-Yan Process in TMD Factorization

π-N Drell-Yan Process in TMD Factorization

Boer-Mulders effect in the unpolarized pion induced Drell–Yan process at COMPASS within TMD factorization

Boer-Mulders function of pion meson and $q_T$-weighted $\cos2ϕ$ asymmetry in the unpolarized $π^- p$ Drell-Yan at COMPASS

Contact Info

Product

Resources

About