Spin asymmetry in proton-proton collisions as a probe of sea and gluon polarization in a proton

Cheng, H. P.; Lai, Sheng‐Nan

doi:10.1103/physrevd.41.91

Cited by 63 publications

(37 citation statements)

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“…In the Cheng-Fischbach model [153,154], later refined by Callaway and Ellis [140] and Cheng and Lai [155], it is simply assumed that the polarized quark distributions are related to the unpolarized ones via…”

Section: The Drell-hearn-gerasimov Sum Rulementioning

confidence: 99%

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Spin physics and polarized structure functions

2000

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A review on the theoretical aspects and the experimental results of polarized deep inelastic scattering and of other hard scattering processes is presented. The longitudinally polarized structure functions are introduced and cross section fromulae are given for the case of photon as well as W ± and Z 0 exchange. Results from the SLAC and CERN polarization experiments are shown and compared with each other as well as their implications for the integrated g 1 (x, Q 2 ) are reviewed. More recent experiments presently underway (like HERMES at DESY) and future projects (like RHIC at BNL, HERA-N and a polarized HERA collider at DESY) are discussed too. The QCD interpretation and the LO and NLO Q 2 -evolution of g 1 , i.e. of the longitudinally polarized parton densities, is discussed in great detail, in particular the role of the polarized gluon density, as well as the expectations for x → 0. Particular emphasis is placed on the first moment of the polarized structure function in various factorization schemes, which is related to the axial anomaly, and on its relevance for understanding the origin of the proton spin. Sum rules (i.e. relations between moments of the structure functions) are derived and compared with recent experimental results. Various other phenomenological applications are discussed as well, in particular the parametrizations of polarized parton densities as obtained from recent data and their evolution in Q 2 . Furthermore, jet, heavy quark and direct photon production are reviewed as a sensitive probe of the polarized gluon density, and the physics prospects of the future polarized experiments at RHIC ( p p) and a polarized HERA collider ( e p) are studied. DIS semi-inclusive asymmetries and elastic neutrino-proton scattering are reviewed, which will help to disentangle the various polarized flavor densities in the nucleon. The status of single and double spin asymmetries, and the observation of handedness in the final state, are discussed as well. Structure 1 functions for higher spin hadrons and nuclei are defined and possible nuclear effects on high energy spin physics are reviewed. The theoretical concept of spin-dependent parton distributions and structure functions of the polarized photon is presented and possibilities for measuring them are briefly discussed. Various nonperturbative approaches to understand the origin of the proton spin are reviewed, such as the isosinglet U A (1) Goldberger-Treiman relation, lattice calculations and the chiral soliton model of the nucleon. The physical interpretation and model calculations of the transverse structure function g 2 are presented, as well as recent twist-3 measurements thereof, and the Burkhardt-Cottingham sum rule is revisited. Finally, the physics of chiral-odd 'transversity' distributions is described and experimental possibilities for delineating them are reviewed, which will be important for a complete understanding of the leading twist-2 sector of the nucleon's parton structure. In the Appendix the full 2-loop anomalous dimension...

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Section: The Drell-hearn-gerasimov Sum Rulementioning

confidence: 99%

“…Furthermore, Cheng and Lai [155] have chosen α(x) = x 0.26 . Roughly, typical values of x 0 and p are of the order 0.5.…”

Section: The Drell-hearn-gerasimov Sum Rulementioning

confidence: 99%

Spin physics and polarized structure functions

2000

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“…The results of these studies have been mainly positive although in the case of the usefulness of (inclusive) polarized prompt photon production for settling the AG question next-to-leading order (O(cmZ)) studies [12,13,14] have been performed, examining the gf [9,10]. In this context, first leading order (O(ozoz8)) studies [11] and more recently tion g]' [8] and the more recent SMC and El42 Collaboration results on the neutron's surprising result of the EMC measurement of the spin dependent proton structure func measure the polarized gluon distribution AG of the proton has been stimulated by the prompt photon production for longitudinal polarization of the proton beams in order to has been studied quite extensively [1][2][3][4][5][6][7].…”

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confidence: 99%

“…(19), (22) and (25)- (27) now the (consistent) HVBM-scheme [32] was used to deal with 75 and 6,,,,,,., in n = 4 -2T recently calculated in refs. [12,13] in the W.-scheme. In the latter calculation [13] prompt photon production needed in the polarized versions of eqs.…”

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confidence: 99%

Polarized and unpolarized isolated prompt photon production beyond the leading order

1994

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at colliders. OCR Output the isolation parameters and study the effects the isolation cuts have on the cross section unpolarized case. We demonstrate the good accuracy of our method over a wide range of der, taking into account also the next-to-leading order fragmentation contribution in the for polarized and unpolarized isolated prompt photon production in next-to-leading or We present a simple and accurate analytical method for calculating the cross section Abstract D

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“…Production of direct photons at large transverse momentum with longitudinally polarized proton beams is a very promising method to measure gluon polarization Δg [33] 2.5. Spin-dependent effects in elastic pp, dp and dd scattering.…”

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confidence: 99%

Spin physics experiments at NICA-SPD with polarized proton and deuteron beams

et al. 2016

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We propose to perform measurements of asymmetries of the DY pair"s production in collisions of non-polarized, longitudinally and transversally polarized protons and deuterons which provide an access to all leading twist collinear and TMD PDFs of quarks and anti-quarks in nucleons. The measurements of asymmetries in production of J/Ψ and direct photons will be performed as well simultaneously with DY using dedicated triggers. The set of these measurements will supply complete information for tests of the quark-parton model of nucleons at the QCD twisttwo level with minimal systematic errors. PAC Recommendations:….The PAC heard with interest a report on the preparation of the Letter of Intent "Spin physics experiments at NICA-SPD with polarized proton and deuteron beams" presented by I. Savin. The PAC is pleased to see the first steps toward formation of an international collaboration around the SPD experiment. The PAC regards the SPD experiment as an essential part of the NICA research program and encourages the authors of the Letter of Intent to prepare a full proposal and present it at one of the forthcoming meetings of the PAC. … --

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Spin asymmetry in proton-proton collisions as a probe of sea and gluon polarization in a proton

Cited by 63 publications

References 50 publications

Spin physics and polarized structure functions

Spin physics and polarized structure functions

Polarized and unpolarized isolated prompt photon production beyond the leading order

Spin physics experiments at NICA-SPD with polarized proton and deuteron beams

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