Single spin asymmetry in lepton angular distribution of Drell-Yan processes

2015

J. High Energ. Phys.

Self Cite

Abstract:The collinear factorization at twist-3 for Drell-Yan processes is studied with the motivation to solve the discrepancy in literature about the single spin asymmetry in the lepton angular distribution, and to show how QCD gauge invariance is realized in the hadronic tensor. The obtained result here agrees with our early result derived with a totally different approach. In addition to the asymmetry we can construct another two observables to identify the spin effect. We show that the gauge invariance of different contributions in the hadronic tensor is made in different ways by summing the effects of gluon exchanges. More interestingly is that we can show that the virtual correction to one structure function of the hadronic tensor, hence to some weighted SSA observables, is completely determined by the quark form factor. This will simplify the calculation of higher order corrections. The corresponding result in semi-inclusive DIS is also given for the comparison with Drell-Yan processes.

Section: Jhep02(2015)163supporting

confidence: 88%

Section: Jhep02(2015)163mentioning

confidence: 88%

Section: Jhep02(2015)163mentioning

confidence: 88%

“…In this work we will work in Feynman gauge. The asymmetry A N has been studied in several works [9][10][11][12][13][14][15][16][17][18]. As mentioned, different results exist.…”

Section: Jhep02(2015)163mentioning

confidence: 99%

See 2 more Smart Citations

Gauge invariance and QCD twist-3 factorization for single spin asymmetries

2015

J. High Energ. Phys.

Self Cite

“…Therefore, one needs to use multi-parton state instead of a single parton state to study those structure functions. Such a study for SSA has been done mainly in the framework of collinear factorization in [18][19][20][21]. The approach with multi-parton states has provided a different way to solve some discrepancies in collinear factorization of SSA [21,22].…”

Section: Introductionmentioning

confidence: 99%

QCD corrections of all structure functions in transverse momentum dependent factorization for Drell-Yan processes

2014

J. High Energ. Phys.

Self Cite

Abstract:We study the one-loop correction in Transverse-Momentum-Dependent(TMD) factorization for Drell-Yan processes at small transverse momentum of the lepton pair. We adopt the so-called subtractive approach, in which one can systematically construct contributions for subtracting long-distance effects represented by diagrams. The perturbative parts are obtained after the subtraction. We find that the perturbative coefficients of all structure functions in TMD factorization at leading twist are the same. The perturbative parts can also be studied with scattering of partons instead of hadrons. In this way, the factorization of many structure functions can only be examined by studying the scattering of multi-parton states, where there are many diagrams. These diagrams have no similarities to those treated in the subtractive approach. As an example, we use existing results of one structure function responsible for Single-Spin-Asymmetry, to show that these diagrams in the scattering of multi-parton states are equivalent to those treated in the subtractive approach after using Ward identity.

One-loop corrections to single spin asymmetries at twist-3 in Drell-Yan processes

Chen

2017

Phys. Rev. D

We study single spin asymmetries at one-loop accuracy in Drell-Yan processes in which one of the initial hadrons is transversely polarized. The spin-dependent part of differential cross-sections can be factorized with various hadronic matrix elements of twist-2 and twist-3 operators. These operators can be of even-and odd-chirality. In this work, the studied observables of asymmetries are differential crosssections with different weights. These weights are selected so that the observables are spin-dependent and their virtual corrections are completely determined by the quark form factor. In the calculations of one-loop corrections we meet collinear divergences in the contributions involving chirality-odd and chirality-even operators. We find that all of the divergences can be correctly subtracted. Therefore, our results give an explicit example of QCD factorization at one-loop with twist-3 operators, especially, QCD factorization with chirality-odd twist-3 operators.have nonzero orbital angular momenta. Another one is the correlation defined with a chirality-odd operator for an unpolarized hadron. The involved contribution is combined with the twist-2 transversity parton distribution, which is not well-known. In hadronic processes there are usually significant corrections from next-to-leading order. With our results at one-loop, the twist-3 parton distributions can be extracted from experimental results more accurately than with tree-results. At one-loop twist-3 gluon distribution will contribute. Knowing the one-loop correction, it can help to extract the twist-3 gluon distribution. Currently, the relevant experiment can be perform at RHIC and Compass, where transversely polarized proton beam or target are available.SSA at tree-level in Drell-Yan processes has been studied extensively. In [3,4,6,5,7,8] the effect of SSA has been studied in the case where the transverse momentum of the lepton pair is small and approaching to zero. The effect is at order of O(α 0 s ). For the case of the large transverse momentum SSA has been studied in [9,10,11,12,13,14], where the effect of SSA is at order of O(α s ). While calculations beyond tree-level in QCD factorization at twist-2 are rather standard and many one-loop results exist, there are not many results of one-loop calculation with twist-3 factorization. For Drell-Yan processes there is only one work in [15] where one weighted differential cross-section of SSA involving the twist-3 quark-gluon operator of [1,2] is calculated at one-loop. For Semi-Inclusive DIS different parts of one-loop results about SSA can be found in [16,17,18]. One-loop study of twist-3 factorization for DIS has been performed in [19].Recently the complete twist-3 part of the hadronic tensor of Drell-Yan process and of Semi-Inclusive DIS has been derived at the tree-level O(α 0 s ) for the first time in [8,20], respectively. According to these results one can systematically construct weighted observables of SSA. An interesting finding in these works is that the twist-3 hadronic tensors contain a ...