TRANSVERSE SPIN AND TRANSVERSE MOMENTUM EFFECTS AT COMPASS

The study of transverse spin and transverse momentum effects is part of the scientific program of COMPASS, a fixed target experiment at the CERN SPS. For these studies, a 160 GeV/c momentum muon beam is scattered on a transversely polarized nucleon target, and the scattered muon and the forward going hadrons produced in DIS processes are reconstructed and identified in a magnetic spectrometer. The measurements have been performed on a deuteron target in 2002, 2003 and 2004, and on a proton target in 2007. The main results obtained measuring single spin asymmetries are reviewed, with particular emphasis on the most recent proton measurements. After two years of spectroscopy measurements with hadron beams, in 2008 and 2009, the Collaboration will resume measurements with the muon beam and a transversely polarized target in 2010.

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COMPASS RESULTS ON TMD OBSERVABLES

International Journal of Modern Physics Conference Series ◽

10.1142/s201019451200904x ◽

2012 ◽

Vol 20 ◽

pp. 9-18

Author(s):

◽

ANNA MARTIN

Keyword(s):

Transverse Momentum ◽

Inelastic Scattering ◽

Deep Inelastic Scattering ◽

Muon Beam ◽

Transverse Spin ◽

Scientific Program ◽

Fixed Target ◽

Transverse Structure ◽

Target Experiment ◽

Fixed Target Experiment

The study of the transverse spin and transverse momentum structure of the nucleon is an important part of the scientific program of COMPASS, a fixed target experiment taking data at the CERN SPS since 2002. In these ten years COMPASS has produced a number of interesting results by measuring the forward going hadrons produced in deep inelastic scattering of a 160 GeV muon beam off polarized deuteron and proton targets. The COMPASS contribution to the understanding of the transverse structure of the nucleon, and the possible future contributions, are briefly reviewed here.

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KANE-PUMPLIN-REPKO FACTORIZATION: ITS APPLICATION TO PRECISION MEASUREMENTS OF TRANSVERSE SPIN ASYMMETRIES AND TO THE STUDY OF TMD EVOLUTION

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194514600027 ◽

2014 ◽

Vol 25 ◽

pp. 1460002 ◽

Cited By ~ 5

Author(s):

DENNIS SIVERS

Keyword(s):

Transverse Momentum ◽

Inelastic Scattering ◽

Precision Measurements ◽

Transverse Spin ◽

Transverse Momentum Dependent ◽

Spin Asymmetries ◽

Single Spin ◽

Hadronic Structure ◽

Single Spin Asymmetries ◽

Fundamental Understanding

This article presents a summary of overlapping presentations by the author to the QCD Evolution 2013 Workshop (Jefferson Lab, May 6-10, 2013) and to the Opportunities for Polarized Physics at Fermilab workshop (Fermilab, May 20-22, 2013). It contains an introduction to the concept of Kane-Pumplin-Repko (KPR) factorization and describes how this concept can be used in the analysis of high precision measurements of parity-conserving transverse single-spin asymmetries. The discussion demonstrates that such measurements can not only probe directly for specific mechanisms that enhance our fundamental understanding of nonperturbative QCD dynamics but, because transverse spin asymmetries are unambiguously parameterized by a spin-directed momentum shift, 〈δkTN (x, μ2)〉 such measurements can also be used to calibrate other phenomenological applications of transverse momentum dependent distributions (TMDs) and of TMD evolution. The calibration supplied by these measurements can thus enable the use of TMD factorization for the exploration of a broad range of other aspects of hadronic structure. KPR factorization ensures that 〈δkTN (x, μ2)〉 remains invariant under TMD evolution and this invariance can be used in the precision comparison of transverse single-spin asymmetries in the Drell-Yan process with those in Semi-inclusive deep inelastic scattering.

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AN of Single Heavy Flavor Decay Muon in the PHENIX Experiment at RHIC

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194516600430 ◽

2016 ◽

Vol 40 ◽

pp. 1660043 ◽

Cited By ~ 1

Author(s):

Xiaorong Wang ◽

Feng Wei

Keyword(s):

Transverse Momentum ◽

Spin Asymmetry ◽

Single Spin Asymmetry ◽

Transverse Spin ◽

Heavy Flavor ◽

Spin Asymmetries ◽

Single Spin ◽

Phenix Experiment ◽

Single Spin Asymmetries ◽

Heavy Flavor Production

Transverse single-spin asymmetries provide valuable information about the spin structure of the nucleon. At RHIC energies, heavy-flavor production is dominated by gluon-gluon fusion, and the subsequent decay into high [Formula: see text] electrons or muons can be observed statistically in a collider detector like PHENIX. The transverse single-spin asymmetry in heavy-flavor production originates from the initial state correlation between the internal transverse momentum of the parton and the transverse spin of the nucleon (similar with the known Sivers effect). The measurement of transverse single-spin asymmetry of single muons from heavy flavor decay at RHIC serves as a clean probe and would provide important information on the gluon Sivers function. In 2012, the PHENIX experiment collected 9.2 [Formula: see text] integrated luminosity in transversely polarized [Formula: see text] collisions at [Formula: see text] = 200 GeV with a polarization of [Formula: see text]. The signal-to-background ratio was improved by a factor of two compared to the previous RHIC 2006 and 2008 results in high transverse momentum region ([Formula: see text]GeV). The recent PHENIX preliminary results of transverse single-spin asymmetries of single heavy flavor decay muon at forward-rapidity will be shown and the possible improvement on this measurement in 2015 with the help of the FVTX detector will be discussed.

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Transverse Single-Spin Asymmetries in Proton-Proton Collisions at the AFTER@LHC Experiment in a TMD Factorisation Scheme

Advances in High Energy Physics ◽

10.1155/2015/475040 ◽

2015 ◽

Vol 2015 ◽

pp. 1-12 ◽

Cited By ~ 10

Author(s):

M. Anselmino ◽

U. D’Alesio ◽

S. Melis

Keyword(s):

Spin Asymmetry ◽

Parton Model ◽

Fixed Target ◽

Proton Proton ◽

Spin Asymmetries ◽

Proton Collisions ◽

Single Spin ◽

Single Spin Asymmetries ◽

Target Experiment ◽

Proton Proton Collisions

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.

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Studies of Transverse-Momentum-Dependent Distributions with a Fixed-Target ExpeRiment Using the LHC Beams (AFTER@LHC)

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194516601071 ◽

2016 ◽

Vol 40 ◽

pp. 1660107 ◽

Cited By ~ 4

Author(s):

L. Massacrier ◽

M. Anselmino ◽

R. Arnaldi ◽

S. J. Brodsky ◽

V. Chambert ◽

...

Keyword(s):

Transverse Momentum ◽

Nuclear Physics ◽

Transverse Spin ◽

Fixed Target ◽

Transverse Momentum Dependent ◽

Spin Asymmetries ◽

Bent Crystal ◽

Target Mode ◽

Target Experiment ◽

Fixed Target Experiment

We report on the studies of Transverse-Momentum-Dependent distributions (TMDs) at a future fixed-target experiment –AFTER@LHC– using the [Formula: see text] or Pb ion LHC beams, which would be the most energetic fixed-target experiment ever performed. AFTER@LHC opens new domains of particle and nuclear physics by complementing collider-mode experiments, in particular those of RHIC and the EIC projects. Both with an extracted beam by a bent crystal or with an internal gas target, the luminosity achieved by AFTER@LHC surpasses that of RHIC by up to 3 orders of magnitude. With an unpolarised target, it allows for measurements of TMDs such as the Boer-Mulders quark distributions and the distribution of unpolarised and linearly polarised gluons in unpolarised protons. Using polarised targets, one can access the quark and gluon Sivers TMDs through single transverse-spin asymmetries in Drell-Yan and quarkonium production. In terms of kinematics, the fixed-target mode combined with a detector covering [Formula: see text] allows one to measure these asymmetries at large [Formula: see text] in the polarised nucleon.

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Study of single-spin asymmetries with polarized target at the SPASCHARM experiment at U70 accelerator

Journal of Physics Conference Series ◽

10.1088/1742-6596/798/1/012096 ◽

2017 ◽

Vol 798 ◽

pp. 012096

Author(s):

V V Abramov ◽

N A Bazhanov ◽

N I Belikov ◽

A A Borisov ◽

N S Borisov ◽

...

Keyword(s):

Spin Asymmetries ◽

Single Spin ◽

Polarized Target ◽

Single Spin Asymmetries

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MEASUREMENT OF FORWARD JETS AT RHIC

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194514600222 ◽

2014 ◽

Vol 25 ◽

pp. 1460022 ◽

Cited By ~ 1

Author(s):

◽

L. C. BLAND

Keyword(s):

Angular Momentum ◽

Transverse Momentum ◽

Orbital Angular Momentum ◽

Initial State ◽

Spin Asymmetries ◽

Jet Production ◽

Single Spin ◽

Single Spin Asymmetries ◽

Forward Jets

We present first measurements of forward jet production from p↑ + p collisions at [Formula: see text] GeV, including transverse single spin asymmetries. These asymmetries are expected to be sensitive to spin-correlated transverse momentum in the initial state, which is particularly interesting because it is related to orbital angular momentum in the proton.

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Introduction to the Transverse-Momentum-Weighted Technique in the Twist-3 Collinear Factorization Approach

Advances in High Energy Physics ◽

10.1155/2019/4825790 ◽

2019 ◽

Vol 2019 ◽

pp. 1-15 ◽

Cited By ~ 1

Author(s):

Hongxi Xing ◽

Shinsuke Yoshida

Keyword(s):

Transverse Momentum ◽

Leading Order ◽

Precise Description ◽

Collinear Factorization ◽

Factorization Approach ◽

Hard Part ◽

Spin Asymmetries ◽

Single Spin ◽

Single Spin Asymmetries ◽

Successful Approach

The twist-3 collinear factorization framework has drawn much attention in recent decades as a successful approach in describing the data for single spin asymmetries (SSAs). Many SSAs data have been experimentally accumulated in a variety of energies since the first measurement was done in the late 1970s and it is expected that the future experiments like Electron-Ion-Collider will provide us with more data. In order to perform a consistent and precise description of the data taken in different kinematic regimes, the scale evolution of the collinear twist-3 functions and the perturbative higher-order hard part coefficients are mandatory. In this paper, we introduce the techniques for next-to-leading order (NLO) calculation of transverse-momentum-weighted SSAs, which can be served as a useful tool to derive the QCD evolution equation for twist-3 functions and to verify the QCD collinear factorization for twist-3 observables at NLO, as well as obtain the finite NLO hard part coefficients.

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A Gas Target Internal to the LHC for the Study of pp Single-Spin Asymmetries and Heavy Ion Collisions

Advances in High Energy Physics ◽

10.1155/2015/463141 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 6

Author(s):

Colin Barschel ◽

Paolo Lenisa ◽

Alexander Nass ◽

Erhard Steffens

Keyword(s):

Areal Density ◽

Mass Range ◽

Heavy Ion ◽

Inert Gases ◽

Spin Asymmetries ◽

Single Spin ◽

Ion Collisions ◽

Gas Target ◽

Single Spin Asymmetries ◽

Target Experiment

We discuss the application of an open storage cell as gas target for a proposed LHC fixed-target experiment AFTER@LHC. The target provides a high areal density at minimum gas input, which may be polarized1H,2H, or3He gas or heavy inert gases in a wide mass range. For the study of single-spin asymmetries in pp interaction, luminosities of nearly 1033/cm2 s can be produced with existing techniques.

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