Nucleon Spin Structure with hadronic collisions at COMPASS

Radici, Marco; Conti, Francesco; Bacchetta, Alessandro; Bianconi, Andrea

doi:10.48550/arxiv.0708.0232

Cited by 3 publications

(7 citation statements)

References 45 publications

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“…Monte Carlo simulations about the feasibility of measurements of the asymmetries ( 31) and ( 32) at GSI-FAIR, COMPASS, and RHIC, were presented in Refs. [31,32,46,47]. Predictions based on our diquark spectator model are displayed in Sec.…”

Section: B Drell-yanmentioning

confidence: 99%

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Weighted azimuthal asymmetries in a diquark spectator model

et al. 2010

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We analytically calculate weighted azimuthal asymmetries in semi-inclusive lepton-nucleon deepinelastic scattering and Drell-Yan processes, using transverse-momentum-dependent partonic densities obtained in a diquark spectator model. We compare the asymmetries with available preliminary experimental data, in particular for the Collins and the Sivers effect. We make predictions for other cases of interest in running and planned experiments.

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Section: B Drell-yanmentioning

confidence: 99%

“…UT /ã T T from Eq. ( 32) for the pp ↑ → µ + µ − X process that could be studied at PAX with antiproton beams colliding on a transversely polarized proton target [25,46,47]. Conventions and notations are the same as in the previous figure.…”

Section: The Ssa In Drell-yanmentioning

confidence: 99%

Weighted azimuthal asymmetries in a diquark spectator model

et al. 2010

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“…[13,23,24,25,26,27,28,29]). From the experimental side, a model could be useful to estimate the size of observables in different processes and kinematical regimes [30,31,32,33,34,35,36] and to set up Monte Carlo simulations [37,38,39,40,41].…”

Section: Introductionmentioning

confidence: 99%

Transverse-momentum distributions in a diquark spectator model

2008

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All the leading-twist parton distribution functions are calculated in a spectator model of the nucleon, using scalar and axial-vector diquarks. Single gluon rescattering is used to generate T-odd distribution functions. Different choices for the diquark polarization states are considered, as well as a few options for the form factor at the nucleon-quark-diquark vertex. The results are listed in analytic form and interpreted in terms of light-cone wave functions. The model parameters are fixed by reproducing the phenomenological parametrization of unpolarized and helicity parton distributions at the lowest available scale. Predictions for the other parton densities are given and, whenever possible, compared with available phenomenological parametrizations.Comment: 42 pages, 13 figures in .eps format. RevTeX style. Minor typos corrected, added one referenc

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“…By measuring different observables in Semi-Inclusive Deep Inelastic Scattering (SIDIS), TMDs combined with fragmentation functions (as a quark materialises as a detected hadron) can be determined. The feasibility of separating TMDs [45,46] has been shown using results from Hermes [47,46] and Figure 12. A contour plot of the k ⊥ distribution of unpolarised quarks inside a proton that is coming towards you.…”

Section: Current Quarks and Perturbation Theorymentioning

confidence: 99%

“…These effects allow the angular momentum carried by quarks to be determined. COMPASS [49,45] providing a multi-dimensional image of the proton. An illustrative example is provided by the Sivers function, Fig.…”

Section: Current Quarks and Perturbation Theorymentioning

confidence: 99%

Evolving images of the proton: hadron physics over the past 40 years

Pennington¹

2016

J. Phys. G: Nucl. Part. Phys.

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Once upon a time, the world was simple: the proton contained three quarks, two ups and a down. How these give the proton its mass and its spin seemed obvious. Over the past forty years the proton has become more complicated, and how even these most obvious of its properties is explained in a universe of quarks, antiquarks and gluons remains a challenge. That this should be so should come as no surprise. Quantum Chromodynamics, the theory of the strong interaction, is seemingly simple, and its consequences are straightforward in the domain of hard scattering where perturbation theory applies. However, the beauty of the hadron world is its diversity. The existence of hadrons, their properties, and their binding into nuclei do not appear in the Lagrangian of QCD. They all emerge as a result of its strong coupling. Strong coupling QCD creates complex phenomena, much richer than known 40 years ago: a richness that ensures colour confinement and accounts for more than 95% of the mass of the visible Universe. How strong coupling QCD really works requires a synergy between experiment and theory. A very personal view of these fascinating developments in cold QCD is presented. arXiv:1604.01441v1 [hep-ph] 5 Apr 2016Fifty years ago there was no microscopic theory of hadron dynamics. Other than protons, hadrons appeared as resonances in scattering processes. These all have definite quantum numbers: spin J, parity P , isospin I, and in the case of mesons, charge conjugation C. The description of their interactions is governed by the general properties of scattering and reaction theory. Guided only by the requirement that interactions should be causal, relativistic and conserve probability, the S-(or scattering) matrix obeys analyticity, crossing symmetry and unitarity [9,10]. Almost everything else was modelling. Nevertheless, it was established that the definition of the state in the spectrum of hadrons is a pole of the S-matrix in the complex energy plane. This will produce a textbook "resonant" peak in the cross-section for scattering in a channel to which the resonance couples, if this state is isolated from other resonances and other strongly coupled thresholds. The search for resonances, states in the spectrum of hadrons, is often thought of as bump-hunting, but really it is pole-vaulting. Reconciling unitarity in a direct channel process with unitarity in the crossed channel gave a whole new meaning to Regge's potential model ideas that angular momentum could be continued from integers to complex values [11]. It was through these S-matrix principles combined with Regge theory that the concept of nuclear democracy and the bootstrap were to be realised. The power of three of the basic properties, crossing, analyticity and Regge theory, to determine reaction amplitudes was explicitly exhibited in the seemingly magic formula of Veneziano [8]. This combined poles in energy with zeros in scattering angles: zeros that give hadrons their spin. This remarkable success in representing scattering by a ratio of Gamma functions led ...

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Nucleon Spin Structure with hadronic collisions at COMPASS

Cited by 3 publications

References 45 publications

Weighted azimuthal asymmetries in a diquark spectator model

Weighted azimuthal asymmetries in a diquark spectator model

Transverse-momentum distributions in a diquark spectator model

Evolving images of the proton: hadron physics over the past 40 years

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