Angular distribution of muon pairs produced by negative pions on deuterium and tungsten in terms of coherent states

Blažek, M.; Biyajima, Minoru; Suzuki, Norihito

doi:10.1007/bf01506541

Cited by 8 publications

(6 citation statements)

References 12 publications

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“…We will return to that extensively in section V. Another approach is put forward in Ref. [26] using coherent states. This can describe the cos 2φ data, however, it fails to describe the function µ in a satisfactory manner.…”

Section: The Unpolarized Drell-yan Processmentioning

confidence: 99%

Investigating the origins of transverse spin asymmetries at BNL RHIC

1999

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We discuss possible origins of transverse spin asymmetries in hadron-hadron collisions and propose an explanation in terms of a chiral-odd T-odd distribution function with intrinsic transverse momentum dependence, which would signal a correlation between the transverse spin and the transverse momentum of quarks inside an unpolarized hadron. We will argue that despite its conceptual problems, it can account for single spin asymmetries, for example in pp ↑ →X, and at the same time for the large cos 2 asymmetry in the unpolarized Drell-Yan cross section, which still lacks understanding. We use the latter asymmetry to arrive at a crude model for this function and show explicitly how it relates unpolarized and polarized observables in the Drell-Yan process, as could be measured with the proton-proton collisions at BNL RHIC. Moreover, it would provide an alternative method of accessing the transversity distribution function h 1 . For future reference we also list the complete set of azimuthal asymmetries in the unpolarized and polarized Drell-Yan process at leading order involving T-odd distribution functions with intrinsic transverse momentum dependence. ͓S0556-2821͑99͒04213-7͔

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Section: The Unpolarized Drell-yan Processmentioning

confidence: 99%

Investigating the origins of transverse spin asymmetries at BNL RHIC

1999

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“…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

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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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“…In the last decade λ, µ, ν were also measured in the p d and pp Drell-Yan processes [84,85]. 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 [1,[86][87][88][89][90][91][92][93]. Here we will only consider the contribution from the coupling of the Boer-Mulders functions, denoted by ν BM .…”

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

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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Angular distribution of muon pairs produced by negative pions on deuterium and tungsten in terms of coherent states

Cited by 8 publications

References 12 publications

Investigating the origins of transverse spin asymmetries at BNL RHIC

Investigating the origins of transverse spin asymmetries at BNL RHIC

π-N Drell-Yan Process in TMD Factorization

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

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