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

Wang, Zhengxian; Wang, Xiaoyu; Lu, Zhun

doi:10.48550/arxiv.1702.03637

Cited by 4 publications

(6 citation statements)

References 61 publications

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“…(34) and (36) in Ref. [113], in which the collinear twist-3 correlation function T (σ) q,F at the initial energy scale was obtained by adopting a model result of the Boer-Mulders function of the pion meson calculated from the light-cone wave functions [125]. For the scale evolution of T (σ) q,F , the exact evolution effect has been studied in Ref.…”

Section: The Boer-mulders Function Of the Pion Mesonmentioning

confidence: 99%

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π-N Drell-Yan Process in TMD Factorization

Wang

Lü

2019

Advances in High Energy Physics

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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.

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Section: The Boer-mulders Function Of the Pion Mesonmentioning

confidence: 99%

“…IV C, the Boer-Mulders function of the pion wals adopted from the model calculation in Ref. [125]. Here we plot the estimated asymmetry ν BM as function of x p , x π , x F and q ⊥ in the kinematical region of COMPASS in Fig.…”

Section: B the Sivers Asymmetrymentioning

confidence: 99%

π-N Drell-Yan Process in TMD Factorization

Wang

Lü

2019

Advances in High Energy Physics

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“…In Ref. [34], the integrated unpolarized distribution function and the Boer-Mulders function for the pion meson were calculated by a model, in which the pion wave functions is derived from a light-cone approach. In this work we adopt the results at the model scale µ 2 0 = 0.25GeV 2 as…”

Section: Numerical Estimatementioning

confidence: 99%

“…In Ref. [34], the cos 2φ asymmetry in πp Drell-Yan process was studied in a transverse momentum weighted approach. In that work, the weighted asymmetry was expressed as the product of the first k T -moment of the Boer-Mulders function h ⊥(1) 1…”

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confidence: 99%

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

2018

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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...

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“…We note that similar violations of the positivity bound were also observed in Refs. [58,59]. An explanation was given in Ref.…”

Section: Tmentioning

confidence: 99%

Transverse polarization of the Λ hyperon from unpolarized quark fragmentation in the diquark model

2017

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We investigate the spin-dependent (naive) T-odd fragmentation function D ⊥ 1T , which can provide an explanation on the transverse polarization of the Λ 0 hyperon produced in an unpolarized process. We calculate D ⊥ 1T for light flavors in the spectator diquark model, with a Gaussian form factor at the hyperon-quark-diquark vertex. We include in the calculation both the scalar diquark and axial-vector diquark spectators. We determine the values of the model parameters by fitting the unpolarized fragmentation function D Λ 1 to the DSV parametrization for D Λ 1 . In addition, we compute the longitudinal polarization fragmentation function G Λ 1 and compare it with the known parametrization of G Λ 1 . We also estimate the transverse polarizations of Λ production, in both semi-inclusive deep inelastic scattering and single inclusive e + e − annihilation.

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

Cited by 4 publications

References 61 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

Transverse polarization of the Λ hyperon from unpolarized quark fragmentation in the diquark model

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