scholarly journals Azimuthal asymmetries of charged hadrons produced by high-energy muons scattered off longitudinally polarised deuterons

2010 ◽  
Vol 70 (1-2) ◽  
pp. 39-49 ◽  
Author(s):  
M. G. Alekseev ◽  
◽  
V. Yu. Alexakhin ◽  
Yu. Alexandrov ◽  
G. D. Alexeev ◽  
...  
Keyword(s):  
High Energy ◽  
Charged Hadrons ◽  
Azimuthal Asymmetries

scholarly journals Azimuthal asymmetries of charged hadrons produced in high-energy muon scattering off longitudinally polarised deuterons

2018 ◽  
Vol 78 (11) ◽  
Author(s):  
C. Adolph ◽  
M. Aghasyan ◽  
R. Akhunzyanov ◽  
M. G. Alexeev ◽  
G. D. Alexeev ◽  
...  
Keyword(s):  
High Energy ◽  
Muon Scattering ◽  
High Energy Muon ◽  
Charged Hadrons ◽  
Azimuthal Asymmetries

scholarly journals Polarized Drell-Yan at COMPASS-II: Transverse Spin Physics Program

2016 ◽  
Vol 40 ◽  
pp. 1660109
Author(s):  
Bakur Parsamyan
Keyword(s):  
High Energy ◽  
Muon Beam ◽  
Distribution Functions ◽  
Transverse Spin ◽  
Spin Physics ◽  
Transverse Momentum Dependent ◽  
Spin Asymmetries ◽  
Compass Experiment ◽  
Physics Program ◽  
Azimuthal Asymmetries

Successful realization of polarized Drell-Yan physics program is one of the main goals of the second stage of the COMPASS experiment. Drell-Yan measurements with high energy (190 GeV/c) pion beam and transversely polarized NH3 target have been initiated by a pilot-run in the October 2014 and will be followed by 140 days of data taking in 2015. In the past twelve years COMPASS experiment performed series of SIDIS measurements with high energy muon beam and transversely polarized deuteron and proton targets. Results obtained for Sivers effect and other target transverse spin dependent and unpolarized azimuthal asymmetries in SIDIS serve as an important input for general understanding of spin-structure of the nucleon and are being used in numerous theoretical and phenomenological studies being carried out in the field of transvers-spin physics. Measurement of the Sivers and all other azimuthal effects in polarized Drell-Yan at COMPASS will reveal another side of the spin-puzzle providing a link between SIDIS and Drell-Yan branches. This will be a unique possibility to test universality and key-features of transverse momentum dependent distribution functions (TMD PDFs) using essentially same experimental setup and exploring same kinematic domain. In this review main physics aspects of future COMPASS polarized Drell-Yan measurement of azimuthal transverse spin asymmetries will be presented, giving a particular emphasis on the link with very recent COMPASS results obtained for SIDIS transverse spin asymmetries from four ”Drell-Yan” [Formula: see text]-ranges.

scholarly journals Overview of TMD Evolution

2016 ◽  
Vol 40 ◽  
pp. 1660014 ◽  
Author(s):  
Daniël Boer
Keyword(s):  
Transverse Momentum ◽  
Momentum Distribution ◽  
High Energy ◽  
Transverse Momentum Distribution ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Azimuthal Asymmetries

Transverse momentum dependent parton distributions (TMDs) appear in many scattering processes at high energy, from the semi-inclusive DIS experiments at a few GeV to the Higgs transverse momentum distribution at the LHC. Predictions for TMD observables crucially depend on TMD factorization, which in turn determines the TMD evolution of the observables with energy. In this contribution to SPIN2014 TMD factorization is outlined, including a discussion of the treatment of the nonperturbative region, followed by a summary of results on TMD evolution, mostly applied to azimuthal asymmetries.

scholarly journals Transverse Spin Azimuthal Asymmetries in SIDIS at COMPASS: Multidimensional Analysis

2016 ◽  
Vol 40 ◽  
pp. 1660029 ◽  
Author(s):  
Bakur Parsamyan
Keyword(s):  
High Energy Physics ◽  
Three Dimensional ◽  
High Energy ◽  
Muon Beam ◽  
Distribution Functions ◽  
Multidimensional Analysis ◽  
Transverse Spin ◽  
Hadron Structure ◽  
Transverse Momentum Dependent ◽  
Azimuthal Asymmetries

COMPASS is a high-energy physics experiment operating at the SPS at CERN. Wide physics program of the experiment comprises study of hadron structure and spectroscopy with high energy muon and hadrons beams. As for the muon-program, one of the important objectives of the COMPASS experiment is the exploration of the transverse spin structure of the nucleon via spin (in)dependent azimuthal asymmetries in single-hadron production in deep inelastic scattering of polarized leptons off transversely polarized target. For this purpose a series of measurements were made in COMPASS, using 160 GeV/c longitudinally polarized muon beam and transversely polarized [Formula: see text] (in 2002, 2003 and 2004) and [Formula: see text] (in 2007 and 2010) targets. The experimental results obtained by COMPASS for unpolarized target azimuthal asymmetries, Sivers and Collins effects and other azimuthal observables play an important role in the general understanding of the three-dimensional nature of the nucleon. Giving access to the entire twsit-2 set of transverse momentum dependent parton distribution functions and fragmentation functions COMPASS data triggers constant theoretical interest and is being widely used in phenomenological analyses and global data fits. In this review main focus is given to the very recent results obtained by the COMPASS collaboration from first ever multi-dimensional extraction of transverse spin asymmetries.

scholarly journals GENERALIZED UNIVERSALITY FOR TMD DISTRIBUTION FUNCTIONS

2012 ◽  
Vol 20 ◽  
pp. 66-74 ◽  
Author(s):  
M. G. A. BUFFING ◽  
P. J. MULDERS
Keyword(s):  
Transverse Momentum ◽  
Parton Distribution ◽  
Azimuthal Angle ◽  
High Energy ◽  
Distribution Functions ◽  
Transverse Spin ◽  
Parton Distribution Functions ◽  
Transverse Momentum Dependent ◽  
Spin Asymmetries ◽  
Azimuthal Asymmetries

Azimuthal asymmetries in high-energy processes, most pronounced showing up in combination with single or double (transverse) spin asymmetries, can be understood with the help of transverse momentum dependent (TMD) parton distribution and fragmentation functions. These appear in correlators containing expectation values of quark and gluon operators. TMDs allow access to new operators as compared to collinear (transverse momentum integrated) correlators. These operators include nontrivial process dependent Wilson lines breaking universality for TMDs. Making an angular decomposition in the azimuthal angle, we define a set of universal TMDs of definite rank, which appear with process dependent gluonic pole factors in a way similar to the sign of T-odd parton distribution functions in deep inelastic scattering or the Drell-Yan process. In particular, we show that for a spin 1/2 quark target there are three pretzelocity functions.

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