scholarly journals SINGLE SPIN ASYMMETRIES IN INCLUSIVE HIGH ENERGY HADRON–HADRON COLLISION PROCESSES

2000 ◽  
Vol 15 (07) ◽  
pp. 927-982 ◽  
Author(s):  
ZUO-TANG LIANG ◽  
C. BOROS

It has been realized for quite a long time that single-spin experiments, in which one of the colliding objects is transversely polarized, can be helpful in studying the properties of strong interaction in general and in testing quantum chromodynamics (QCD) in particular. Striking effects have been observed in the past few years which deviate drastically from the expectation of the perturbative QCD parton model. These effects have received much attention. New experiments of the similar type are underway and/or planned. Different theoretical attempts have been made to understand these effects. In this review, the special role played by singly polarized high-energy hadron–hadron collisions in high energy spin physics is emphasized. Characteristics of the available data for inclusive hadron productions are briefly summarized. Different theoretical approaches for such processes are reviewed with special attention to a nonperturbative model which explicitly takes the orbital motion of the valence quarks and hadronic surface effects into account. The connection between such asymmetries and hyperon polarization in unpolarized reactions is discussed. An example of the possible application of such experimental results in other processes is given.

1999 ◽  
Vol 11 (4) ◽  
pp. 703-708 ◽  
Author(s):  
A. Ahmedov ◽  
I.V. Akushevich ◽  
E.A. Kuraev ◽  
P.G. Ratcliffe

1999 ◽  
Vol 11 (4) ◽  
pp. 703 ◽  
Author(s):  
A. Ahmedov ◽  
I.V. Akushevich ◽  
E.A. Kuraev ◽  
P.G. Ratcliffe

2003 ◽  
Vol 18 (16) ◽  
pp. 2871-2892 ◽  
Author(s):  
Stanley J. Brodsky

The advent of back-scattered laser beams for e±e-colliders will allow detailed studies of a large array of high energy γγ and γe collision processes with polarized beams. These include tests of electroweak theory in photon-photon annihilation such as γγ → W+W-, γγ → Higgs bosons, and higher-order loop processes, such as γγ → γγ, Zγ, H0Z0and ZZ. Methods for measuring the anomalous magnetic and quadrupole moments of the W and Z gauge bosons to high precision in polarized electron-photon and photon-photon collisions are discussed. Since each photon can be resolved into a W+W-pair, high energy photon-photon collisions can also provide a remarkably background-free laboratory for studying WW collisions and annihilation. I also review high energy γγ and eγ tests of quantum chromodynamics, including the production of two gluon jets in photon-photon collisions, deeply virtual Compton scattering on a photon target, and leading-twist single-spin asymmetries for a photon polarized normal to a production plane. Exclusive hadron production processes in photon-photon collisions provide important tests of QCD at the amplitude level, particularly as measures of hadron distribution amplitudes which are also important for the analysis of exclusive semi-leptonic and two-body hadronic B-decays.


2021 ◽  
Vol 66 (1) ◽  
pp. 3
Author(s):  
D. Borisyuk ◽  
A. Kobushkin

In the present review, we discuss different aspects of the two-photon exchange (TPE) physics in elastic ep scattering at high Q2, as well as at low Q2. The imaginary part of the TPE amplitude gives rise to beam and target single-spin asymmetries. Different theoretical approaches to the calculation of these observables are considered. The real part of the TPE amplitude influences the unpolarized cross-section and double-spin observables and is, most likely, responsible for the discrepancy between two methods of measurements of the proton form factors. We review different methods of calculations of the TPE amplitudes in the framework of the “hadron” and “quark-gluon” approaches. We discuss the dispersion approach suitable for low and intermediate Q2, which includes elastic and inelastic intermediate hadronic states, as well as the connection of TPE with the proton radius puzzle. The present situation with direct experimental searches for the TPE amplitude in the e+p/e−p charge asymmetry is also discussed, as well as attempts to extract the TPE amplitudes from existing experimental data obtained by the Rosenbluth and double polarization techniques. The TPE physics in other processes such as elastic мp, e-nucleus, and еп scattering is also reviewed.


2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
M. Anselmino ◽  
U. D’Alesio ◽  
S. Melis

The inclusive large-pTproduction of a single pion, jet or direct photon, and Drell-Yan processes, are considered for proton-proton collisions in the kinematical range expected for the fixed-target experiment AFTER, proposed at LHC. For all these processes, predictions are given for the transverse single-spin asymmetry,AN, computed according to a Generalised Parton Model previously discussed in the literature and based on TMD factorisation. Comparisons with the results of a collinear twist-3 approach, recently presented, are made and discussed.


2021 ◽  
Vol 103 (3) ◽  
Author(s):  
Siddhesh Padval ◽  
Rohini M. Godbole ◽  
Abhiram Kaushik ◽  
Anuradha Misra ◽  
Vaibhav S. Rawoot

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