Large analyzing power in inclusive π± production at high xF with a 22-GeV/c polarized proton beam

Krueger, K.; Allgower, C.; Kasprzyk, T.; Spinka, H. M.; Underwood, D. G.; Yokosawa, A.; Bunce, G.; Huang, H.; Makdisi, Y. I.; Roser, T.; Syphers, M.; Belikov, N.I.; Derevschikov, A. A.; Matulenko, Yu. A.; Nogach, L. V.; Nurushev, S. B.; Pavlinov, A. I.; Vasiliev, A.; Bai, Mei; Lee, S.Y; Goto, Y.; Hayashi, Naoki; Ichihara, T.; Okamura, M.; Saito, N.; En’yo, H.; Imai, K.; Kondo, Yoshihiko; Nakada, Y.; Nakamura, Masanobu; Sato, H.; Okamura, H.; Sakai, Hisakazu; Wakasa, T.; Baturine, V.; Ogawa, A.; Ghazikhanian, V.; Igo, G.; Trentalange, S.; Whitten, C.

doi:10.1016/s0370-2693(99)00677-2

Cited by 83 publications

(36 citation statements)

References 15 publications

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“…Antiquark distribution and fragmentation functions can also be defined for the kinematical twist-3 functions as in the case of the functions in (3) and (4). For the distribution functions, quark and antiquark ones are related as fq(…”

Section: A Parameterizations Of Matrix Elements Of Twist-3 Operatorsmentioning

confidence: 99%

“…The first measurements of so-called single-spin asymmetries (SSAs) were made at Argonne National Lab [1] and FermiLab [2] in the mid-1970s, and then continued with FermiLab again in the 1990s [3], and now most recently at AGS [4,5] and RHIC [6][7][8][9][10][11][12][13] at Brookhaven National Lab. All of these experiments involved proton-(anti)proton collisions that produced a single hadron (or jet), and only one of the hadrons involved in the process was transversely polarized.…”

Section: Introductionmentioning

confidence: 99%

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Operator constraints for twist-3 functions and Lorentz invariance properties of twist-3 observables

et al. 2016

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We investigate the behavior under Lorentz tranformations of perturbative coefficient functions in a collinear twist-3 formalism relevant for high-energy observables including transverse polarization of hadrons. We argue that those perturbative coefficient functions can, a priori, acquire quite different yet Lorentz-invariant forms in various frames. This somewhat surprising difference can be traced back to a general dependence of the perturbative coefficient functions on lightcone vectors which are introduced by the twist-3 factorization formulae and which are frame-dependent. One can remove this spurious frame dependence by invoking so-called Lorentz invariance relations (LIRs) between twist-3 parton correlation functions. Some of those relations for twist-3 distribution functions were discussed in the literature before. In this paper we derive the corresponding LIRs for twist-3 fragmentation functions. We explicitly demonstrate that these LIRs remove the lightcone vector dependence by considering transverse spin observables in the single-inclusive production of hadrons in leptonnucleon collisions, N → hX. With the LIRs in hand, we also show that twist-3 observables in general can be written solely in terms of three-parton correlation functions.

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Section: A Parameterizations Of Matrix Elements Of Twist-3 Operatorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Operator constraints for twist-3 functions and Lorentz invariance properties of twist-3 observables

et al. 2016

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“…This has become apparent from studies of the unpolarized gluon distribution in the small-x regime [1][2][3] and, independently, from studies of spin effects in high-energy scattering processes. Scattering experiments involving a spin-polarized proton exhibit large asymmetries in the production of final state particles [4][5][6][7][8][9][10][11][12]. Theoretical studies of these still largely ununderstood single spin asymmetries (SSA) led to the insight that TMDs of both quarks and gluons are sensitive to the flow of the color charge of quarks and gluons in a process and hence that they are in general process specific, i.e.…”

mentioning

confidence: 99%

Single Spin Asymmetries from a Single Wilson Loop

et al. 2016

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We study the leading-power gluon transverse momentum dependent distributions (TMDs) of relevance to the study of asymmetries in the scattering off transversely polarized hadrons. Next-to-leading-order perturbative calculations of these TMDs show that at large transverse momentum they have common dynamical origins, but that in the limit of small longitudinal momentum fraction x only one origin remains. We find that in this limit only the dipole-type gluon TMDs survive and become identical to each other. At small x they are all given by the expectation value of a single Wilson loop inside the transversely polarized hadron, the so-called spin-dependent odderon. This universal origin of transverse spin asymmetries at small x is of importance to current and future experimental studies, paving the way to a better understanding of the role of gluons in the three-dimensional structure of spin-polarized protons.Scattering off protons in high energy particle collisions such as performed at RHIC and LHC, can be described as scattering off quarks and gluons inside the proton. As the energy of the scattering process increases, the gluons play an increasingly important role, as reflected by a fast growing gluon density inside the proton. The limit of high gluon density is the one in which the gluons carry only a very small fraction, x, of the longitudinal momentum of the proton. It is expected on theoretical grounds that the gluon density will not increase without bound towards small x, but rather that it will saturate. Because of the dominance of gluons over quarks and the expected gluon saturation, the description of scattering processes considerably simplifies in the small-x limit. A complication that remains in this limit though, is that gluonic effects do not manifest themselves in the same way in all processes.It has recently become clear that the transverse momentum distribution of gluons inside the proton is not a unique quantity. Different processes may probe different distributions and thus yield different answers. This has become apparent from studies of the unpolarized gluon distribution in the small-x regime [1-3] and, independently, from studies of spin effects in high-energy scattering processes. Scattering experiments involving a spin-polarized proton exhibit large asymmetries in the production of final state particles [4][5][6][7][8][9][10][11][12]. Theoretical studies of these still largely ununderstood single spin asymmetries (SSA) led to the insight that TMDs of both quarks and gluons are sensitive to the flow of the color charge of quarks and gluons in a process and hence that they are in general process specific, i.e. nonuniversal [13]. TMD studies of the color flow dependence are generally not performed in the high gluon density region. In [2,3], the two types of treatments were connected for the case in which neither the proton nor the gluons are spin-polarized. For transversely polarized protons the connection between the TMD and small-x formalisms has so far not been made. This is our aim here.We wil...

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“…Several other analyses furthered the development of this framework -see, e.g., [7][8][9][10][11][12][13][14]. In addition, this theoretical work has been complimented by many experimental measurements of A N at proton-(anti)proton accelerators over the last two decades [15][16][17][18][19][20][21][22][23]. Most of this experimental data has come in the form of light-hadron asymmetries A h N , e.g., h = π, K, η, with the exception of the jet asymmetry A jet N recently measured by the A N DY Collaboration [22].…”

Section: Introductionmentioning

confidence: 91%

Transverse single-spin asymmetries inp↑p→γXfrom quark-gluon-quark correlations in the proton

et al. 2015

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We analyze the transverse single-spin asymmetry in direct photon production from proton-proton collisions, denoted A γ N , within collinear twist-3 factorization. We provide a calculation of the contribution due to quark-gluon-quark correlations in the unpolarized proton as well as summarize previous studies on those effects in the polarized proton. Both soft-gluon poles and soft-fermion poles are considered. From this complete result we then estimate A γ N , including error bands due to uncertainties in the non-perturbative inputs, at kinematics relevant for planned measurements of this observable at the Relativistic Heavy Ion Collider. We find A γ N can allow for a "clean" extraction of the Qiu-Sterman function, which could lead to a definitive solution to the so-called "sign mismatch" crisis. Since we use the Sivers function extracted from semi-inclusive deep-inelastic scattering to develop our input for the Qiu-Sterman function, this reaction can also make a statement about the process dependence of the Sivers function.

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Large analyzing power in inclusive π± production at high xF with a 22-GeV/c polarized proton beam

Cited by 83 publications

References 15 publications

Operator constraints for twist-3 functions and Lorentz invariance properties of twist-3 observables

Operator constraints for twist-3 functions and Lorentz invariance properties of twist-3 observables

Single Spin Asymmetries from a Single Wilson Loop

Transverse single-spin asymmetries inp↑p→γXfrom quark-gluon-quark correlations in the proton

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