SPIN 2018

Session

3D Structure of the Nucleon: TMDs

C

10 Sept 2018, 14:30

University of Ferrara

Conveners

3D Structure of the Nucleon: TMDs

• Bakur Parsamyan (TO)
• James Drachenberg (Abilene Christian University)
• Alessandro Bacchetta (PV)

3D Structure of the Nucleon: TMDs

• Alessandro Bacchetta (PV)
• Bakur Parsamyan (TO)
• James Drachenberg (Abilene Christian University)

3D Structure of the Nucleon: TMDs

• Alessandro Bacchetta (PV)
• Bakur Parsamyan (TO)
• James Drachenberg (Lamar University)

3D Structure of the Nucleon: TMDs

• Alessandro Bacchetta (PV)
• Bakur Parsamyan (TO)
• James Drachenberg (Abilene Christian University)

3D Structure of the Nucleon: TMDs

• James Drachenberg (Abilene Christian University)
• Alessandro Bacchetta (PV)
• Bakur Parsamyan (TO)

3D Structure of the Nucleon: TMDs

• Bakur Parsamyan (TO)
• Alessandro Bacchetta (PV)
• James Drachenberg (Abilene Christian University)

3D Structure of the Nucleon: TMDs

• Bakur Parsamyan (TO)
• Alessandro Bacchetta (PV)
• James Drachenberg (Abilene Christian University)

3D Structure of the Nucleon: TMDs

• James Drachenberg (Abilene Christian University)
• Alessandro Bacchetta (PV)
• Bakur Parsamyan (TO)

59. On the extraction of the non-perturbative transverse momentum dependence of parton distribution and fragmentation functions from data

Francesco Murgia (CA)

10/09/2018, 14:30

3D Structure of the Nucleon: TMDs

Parallel Sessions

Transverse single spin asymmetries for hadron production in polarized semi-inclusive deeply inelastic scattering (SIDIS) are nowadays one of the main source of information on transversity, the quark Sivers distributions and the Collins fragmentation function, and on their transverse momentum dependence. However, in SIDIS the transverse momentum of the final hadron, that is the quantity...

109. COMPASS results on weighted Sivers asymmetry in SIDIS

Anna Martin (TS)

10/09/2018, 14:55

3D Structure of the Nucleon: TMDs

Parallel Sessions

The COMPASS Collaboration has recently measured the Sivers asymmetries weighted with the hadron transverse momentum, analyzing the high statistics data sample collected in 2010 to measure semi-inclusive deep inelastic scattering on a transversely polarised proton target. These asymmetries provide direct information on the Sivers function, which is one of the most studied transverse momentum...

98. Weighted transverse spin asymmetries in 2015 COMPASS Drell–Yan data

Jan Matousek (University and INFN Trieste, Italy)

10/09/2018, 15:20

3D Structure of the Nucleon: TMDs

Parallel Sessions

In 2015 at the COMPASS experiment at CERN a pion beam with momentum of 190 GeV/c interacted with a transversely polarised NH_3 target. Muon pairs produced in the Drell–Yan process were detected. In addition to the extraction of the transverse spin asymmetries (TSAs) from this data, a complementary analysis of the TSAs weighted by powers of the dimuon momentum q_T has been done and will be...

105. Recent Transverse Spin Measurements in pp Collisions with STAR

Prof. Carl Gagliardi (Texas A&M University)

10/09/2018, 15:45

3D Structure of the Nucleon: TMDs

Parallel Sessions

The STAR Collaboration at RHIC is exploring the partonic origin of the proton spin with a broad range of measurements in polarized pp collisions. STAR measurements of the transverse single-spin asymmetry, $A_N$, for $W$ boson production provide the first experimental investigation of the non-universality of the Sivers function. Precise follow-up measurements of $A_N$ for direct photon...

36. Effect of flavor-dependent partonic transverse momentum on the determination of the W mass at hadron colliders

Dr Giuseppe Bozzi (PV)

10/09/2018, 16:40

3D Structure of the Nucleon: TMDs

Parallel Sessions

Within the framework of transverse-momentum-dependent factorization, we investigate for the first time the impact of a flavor-dependent intrinsic transverse momentum of quarks on the production of W bosons in hadronic collisions. We study the transverse-mass, lepton transverse momentum, and missing transverse momentum distributions of the W−decay products by means of a template-fit technique...

202. First CLAS12 results in SIDIS measurements

Marco Mirazita (LNF)

10/09/2018, 17:05

3D Structure of the Nucleon: TMDs

Parallel Sessions

In January 2018, the CLAS12 spectrometer has started taking data using the 10.6 GeV, higly polarized, electron beam on a liquid hydrogen unpolarized target, at a luminosity as high as 10^35 cm^-2 s^-1, about one order of magnitude higher than during the 6 GeV era with the CLAS spectrometer. The high beam quality combined with the large acceptance of CLAS12 will allow for the first time to...

78. Nuclear Dependence of Transverse Single-Spin Asymmetries in Polarized $p$+$A$ Collisions at RHIC

Dr Stephen Pate (New Mexico State University)

10/09/2018, 17:30

3D Structure of the Nucleon: TMDs

Parallel Sessions

Large transverse single-spin asymmetries (TSSA) in hadron production at forward rapidity have been observed in polarized $p$+$p$ interactions for many decades, over a large range of center-of-mass energies, and have led to the investigation of spin-momentum correlations such as the Sivers and Collins effects. In the last few years, it has been discovered at RHIC that these single-spin...

129. First measurement of transverse single spin asymmetry for very forward pi0 production in polarized p+p collisions at sqrt{s} = 510 GeV

Mr Minho Kim (Korea University/ RIKEN)

10/09/2018, 17:55

3D Structure of the Nucleon: TMDs

Parallel Sessions

Non-zero transverse single spin asymmetry, AN, of forward pi0 production in the pseudo rapidity range of 3<eta<4 has been measured by various experiments so far and usually interpreted by hard process mechanism between polarized and unpolarized proton collisions. However, no clue can be found yet if there is a potential contribution from the soft process and recently larger AN was also...

62. First extraction of transversity from data on lepton-hadron scattering and hadronic collisions

Dr Marco Radici (PV)

11/09/2018, 14:30

3D Structure of the Nucleon: TMDs

Parallel Sessions

We present the first extraction of the transversity distribution based on the global analysis of pion-pair production in deep-inelastic scattering and in proton-proton collisions with one transversely polarized proton. The extraction relies on the knowledge of di-hadron fragmentation functions, which are taken from the analysis of electron-positron annihilation data. We compute the tensor...

52. Projections for a future SIDIS measurement on transversely polarized deuterons by the COMPASS Collaboration.

Prof. Franco Bradamante (INFN, Trieste Section)

11/09/2018, 14:55

3D Structure of the Nucleon: TMDs

Parallel Sessions

Since 2005, measurements of Collins and Sivers asymmetries from the HERMES and COMPASS experiments have allowed to assess that the transversity and the Sivers PDF are different from zero and measurable in semi-inclusive DIS on transversely polarized targets. Most of the data were collected on proton targets, only few data were collected in the early phase of the COMPASS experiment on a...

201. Iso-vector transversity quark distributions from lattice QCD

Dr Fernanda Steffens (DESY - Zeuthen)

11/09/2018, 15:20

3D Structure of the Nucleon: TMDs

Parallel Sessions

Using the quark quasi-distribution approach, we present the first direct calculation of the transversity parton distribution function within the nucleon from lattice QCD. The calculation is performed using simulations with the light quark mass fixed to its physical. We employ non-perturbative renormalization to subtract the linear and log divergences present in the bare matrix elements, and...

46. Quark orbital angular momentum in the proton evaluated in Lattice QCD using a direct derivative method

Michael Engelhardt (New Mexico State University)

11/09/2018, 15:45

3D Structure of the Nucleon: TMDs

Parallel Sessions

Quark orbital angular momentum (OAM) in the proton can be calculated directly if a Wigner function encoding the simultaneous distribution of quark transverse positions and momenta is given. This distribution can be accessed via proton matrix elements of a quark bilocal operator (the separation in which is Fourier conjugate to the quark momentum) featuring a momentum transfer (which is...

55. Process dependence of the gluon Sivers function in inclusive pp collisions: theory

Cristian Pisano (CA)

11/09/2018, 16:40

3D Structure of the Nucleon: TMDs

Parallel Sessions

Within the color gauge invariant generalized parton model (CGI-GPM), that includes initial- and final-state interactions in a TMD formalism, we present the complete results, at leading-order, for transverse single-spin asymmetries in the inclusive hadroproduction of pions, direct photons, D mesons and quarkonia.

57. Process dependence of the gluon Sivers function in inclusive pp collisions: phenomenology

Umberto D'Alesio (CA)

11/09/2018, 17:05

3D Structure of the Nucleon: TMDs

Parallel Sessions

Within the so-called color gauge invariant generalized parton model (CGI-GPM), we will discuss how a phenomenological analysis of available SSA data for pion, D meson and J/psi production in pp collisions can be used to put the first constraints on the two universal types of gluon Sivers function. A comparison with the simpler generalized parton model, as well as predictions for SSAs in...

171. J/Psi Transverse Single Spin Asymmetries (TSSA) and Spin Alignment to Decay Leptons in p+p Collisions at RHIC

Dr Sook Hyun Lee (Iowa State University)

11/09/2018, 17:30

3D Structure of the Nucleon: TMDs

Parallel Sessions

The J/Psi, a bound state of charm and anti-charm quark with spin 1, decays into lepton pairs with a large branching ratios. Its production in polarized and unpolarized p+p collisions sheds light on different aspects of QCD. At RHIC energies, charmonium production in $p$+$p$ collisions is dominated by gluon-gluon interaction. As a result, measurements of the TSSA in polarized $p$+$p$ collisions...

124. Transverse Single-Spin Asymmetries of Midrapidity Eta Mesons at PHENIX

Nicole Lewis (PHENIX)

11/09/2018, 17:55

3D Structure of the Nucleon: TMDs

Parallel Sessions

Transverse single-spin asymmetries (TSSAs) of proton-proton collisions have a long history of revealing the richness of QCD. They were originally measured in fixed target experiments and ignored for a couple decades because it was assumed that they came incalculable soft QCD interactions. But they have been found to persist in collisions up to \sqrt{s} = 510 GeV, well into the perturbative...

136. Measurements of azimuthal asymmetries on unpolarized protons

Mr Andrea Moretti (University of Trieste / INFN)

12/09/2018, 14:30

3D Structure of the Nucleon: TMDs

Parallel Sessions

In 2016 and 2017 the COMPASS Collaboration has measured 160 GeV/c muon scattering on a 2.5 m long liquid Hydrogen target. The main goal of the measurement was to access GPDs via the deeply virtual Compton Scattering (DVCS) process, but in parallel SIDIS data were collected to investigate the azimuthal modulations of the hadron lepto-production cross-section. In this talk we present preliminary...

106. Interpretation of the unpolarized azimuthal asymmetries in SIDIS

Albi Kerbizi (TS)

12/09/2018, 14:55

3D Structure of the Nucleon: TMDs

Parallel Sessions

The measurement of azimuthal modulations in hadron leptoproduction on unpolarised nucleons allows to get information on the intrinsic transverse momentum of quarks in a nucleon through both the Cahn effect and the Boer-Mulders function. In particular the latter describes a possible correlation between the intrinsic transverse momentum and the transverse spin of the quarks of an unpolarized...

90. TMD evolution as a double-scale evolution

Dr Alexey Vladimirov (Regensburg University)

12/09/2018, 15:20

3D Structure of the Nucleon: TMDs

Parallel Sessions

Evolution of transverse momentum dependent distributions (TMD evolution) is an evolution with respect to two scales: the renormalization and rapidity scales. The double scale evolution grants a freedom in the definition of physical observables, which naively could lead to ambiguous results. We show that the double-evolution picture has a natural interpretation in terms of evolution potential,...

38. Twist-2 transverse momentum distributions at NNLO in QCD

Mr Daniel Gutiérrez Reyes (Complutense University of Madrid)

12/09/2018, 15:45

3D Structure of the Nucleon: TMDs

Parallel Sessions

The factorization theorem for DY and semi-inclusive DIS holds for all leading twist transverse momentum distributions. However a QCD perturbative calculation shows several important characteristics of spin-dependent distributions. We consider all the different spin-dependent distributions which can be matched onto integrated twist-2 functions, focusing on the transversity and pretzelosity...

35. Difficulties in the description of Drell–Yan processes at low invariant mass and high transverse momentum

Fulvio Piacenza (PV)

12/09/2018, 16:40

3D Structure of the Nucleon: TMDs

Parallel Sessions

In this talk, we discuss the transverse momentum distribution of Drell-Yan lepton pairs in fixed-target Drell-Yan experiments. We show that fixed-order theory underestimates data at large qT, by an amount that cannot be explained by perturbative truncation errors nor PDF uncertainties. We consider a modification of the standard collinear formalism that includes the effect of intrinsic...

82. Understanding SIDIS data from QCD

Jose Osvaldo Gonzalez Hernandez (TO)

12/09/2018, 17:05

3D Structure of the Nucleon: TMDs

Parallel Sessions

The most recent SIDIS measurements have challenged our understanding of factorization theorems in QCD. In order to perform reliable extractions of transverse momentum dependent functions (TMDs) it is essential to understand the extent to which the errors of factorization are under control. In this talk I will discuss about the issues encountered when comparing theory and experiment. I will...

113. Understanding the Large qT spectrum in SIDIS and DY

Nobuo Sato (Jefferson Lab)

12/09/2018, 17:30

3D Structure of the Nucleon: TMDs

Parallel Sessions

In this talk I will discuss recent progress to understand the large qT spectrum in SIDIS and DY.

212. Collinear and TMD parton densities from fits to precision DIS measurements in the parton branching method

Francesco Hautmann (University of Oxford)

12/09/2018, 17:55

3D Structure of the Nucleon: TMDs

Parallel Sessions

Collinear and transverse momentum dependent (TMD) parton densities are obtained from fits to precision measurements of deep inelastic scattering (DIS) cross sections at HERA. The parton densities are evolved by DGLAP evolution with next-to-leading-order (NLO) splitting functions using the parton branching method, allowing one to determine simultaneously collinear and TMD densities for all...

140. Spin and kinematic correlations between partons inside the proton

Ms Sabrina Cotogno (Vrije Universiteit Amsterdam and Nikhef)

13/09/2018, 14:30

3D Structure of the Nucleon: TMDs

Parallel Sessions

In processes where two quarks are extracted from the proton to enter two separate hard scatterings (double parton scattering), the interparton correlations can have an impact on the size of the cross section and significantly alter the distributions of particles in the final state. In this work, we employ different models for the double parton distributions (DPDs) to study the quantum...

89. Quark-gluon correlations in the twist-3 TMD using light-front wave functions.

Simone Rodini (PV & INFN)

13/09/2018, 14:55

3D Structure of the Nucleon: TMDs

Parallel Sessions

Higher-twist transverse-momentum dependent parton distributions (TMDs) go beyond the parton model description of a proton as they describe correlations between quarks and gluons. Higher-twist TMDs, however, turn out to be very elusive objects, as they are difficult to extract from experimental data. Twist-3 distributions can be decomposed as a sum of different contributions. In general, these...

217. Pion-induced Drell-Yan scattering at COMPASS

Caroline Riedl (University of Illinois at Urbana-Champaign)

13/09/2018, 15:20

3D Structure of the Nucleon: TMDs

Parallel Sessions

An overview of pion-induced Drell-Yan (DY) scattering at COMPASS is given. In 2015, COMPASS was scattering a 190 GeV pion beam off a transversely polarized proton target and unpolarized nuclear targets. The Sivers asymmetry, and other spin-dependent azimuthal asymmetry amplitudes, were extracted from these data. The Sivers asymmetry is of particular interest since it is expected to change sign...

26. Spin Physics with a fixed-target experiment at the LHC

Dr Miguel Echevarria (INFN Pavia)

13/09/2018, 16:40

3D Structure of the Nucleon: TMDs

Parallel Sessions

A fixed-target experiment using the LHC beams with a polarized target would offer a unique opportunity to study the internal structure of the nucleon. Recent studies have shown that a number of spin and azimuthal asymmetries are large enough to be precisely measured, allowing to constrain several non-perturbative functions which encode the three-dimensional spin structure of the nucleon, as...

51. Spin dependent gluon distributions and their measurement in heavy quark production processes

Prof. Gary Goldstein (Tufts University)

13/09/2018, 17:05

3D Structure of the Nucleon: TMDs

Parallel Sessions

Gluon pdf’s, GPD’s and TMD’s play a significant role in an array of scattering processes, including SIDIS, DVCS, exclusive meson electroproduction and p p scattering. Spin dependent gluon distributions can lead to distinctive features in the angular dependences and asymmetries of the scattering processes. Of particular interest are heavy quark production processes, wherein spin observables of...

121. Longitudinal and Transverse Spin Transfer to Lambda and anti-Lambda in Polarized p+p Collisions at 200 GeV at STAR

Qinghua Xu (Shandong University)

13/09/2018, 17:55

3D Structure of the Nucleon: TMDs

Parallel Sessions

The longitudinal or transverse spin transfer to Lambda and anti-Lambda hyperons in polarized proton-proton collisions is expected to be sensitive to the helicity or transversity distributions of strange and anti-strange quarks of the proton, and to the corresponding polarized fragmentation function. We report the first measurement of the transverse spin transfer to Lambda and anti-Lambda along...