Hadron transverse momentum distributions from SIDIS and pp

Hadron transverse momentum distributions from SIDIS and pp Andrea Bressan University of Trieste and INFN 3 D PARTON DISTRIBUTIONS: PATH TO THE LHC, 29/11 - 2/12/2016 INFNLABORATORI NAZIONALI DI FRASCATI

Transverse structure of the Nucleon Confinement Scale Transverse momentum Transverse position High Energy Probe Hard Scale Tra Photon Virtuality Q 2 LNF 1/12/2016 3 D Parton Distributions ns ve rse pl an e 2

Confined parton motion in a hadron • LNF 1/12/2016 3 D Parton Distributions 3

Structure of proton • Longitudinal motion only Longitudinal + transverse motion LNF 1/12/2016 3 D Parton Distributions 4

New ways to look at partons • We not only need to know that partons have longitudinal momentum, but must have transverse degrees of freedom as well • Partons in transverse coordinate space • Generalized parton distributions (GPDs) • Partons in transverse momentum space • Transverse-momentum distributions (TMDs) • Both? Wigner distributions! LNF 1/12/2016 3 D Parton Distributions 5

Factorization in QCD – SIDIS • TMD Fragmentation Soft Factor TMD Distribution LNF 1/12/2016 3 D Parton Distributions 6

Transverse-Momentum Dependent PDFs • LNF 1/12/2016 3 D Parton Distributions 7

TMD evolution: • Evolution of longitudinal/ collinear part LNF 1/12/2016 Evolution of transverse part (Sudakov form factor) 3 D Parton Distributions Non-perturbative part has to be fitted to experimental data The key ingredient is spin-independent 8

SIDIS Experiments • LNF 1/12/2016 3 D Parton Distributions 9

Kinematic coverage LNF 1/12/2016 3 D Parton Distributions 10

Kinematic coverage COMPASS HERMES JLAB 12 LNF 1/12/2016 3 D Parton Distributions 11

Berger criterion (separation of CFR &TFR) The typical hadronic correlation length in rapidity is LNF 1/12/2016 3 D Parton Distributions 12

Unpolarised Azimuthal Modulation LNF 1/12/2016 3 D Parton Distributions 13

Unpolarised Azimuthal Modulation LNF 1/12/2016 3 D Parton Distributions 14

Unpolarised Azimuthal Modulation Bacchetta, Diehl, Goeke, Metz, Mulders and Schlegel JHEP 0702: 093 (2007) LNF 1/12/2016 3 D Parton Distributions 15

Unpolarised Azimuthal Modulation LNF 1/12/2016 3 D Parton Distributions 16

Experimental status • EMC E 665 Fits from M. Anselmino, V. Barone, E. Boglione, U. D’Alesio, F. Murgia, A. Prokudin, A. Kotzinian, and C. Turk LNF 1/12/2016 3 D Parton Distributions 17

Multiplicity distributions • C. Weiss LNF 1/12/2016 3 D Parton Distributions 18

Importance of unpolarized SIDIS • LNF 1/12/2016 3 D Parton Distributions 19

Importance of unpolarized SIDIS LNF 1/12/2016 3 D Parton Distributions 20

Importance of unpolarized SIDIS LNF 1/12/2016 3 D Parton Distributions 21

Mean values LNF 1/12/2016 3 D Parton Distributions 22

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TMD evolution: multiplicity distribution in SIDIS • Comparison to COMPASS data LNF 1/12/2016 Echevarria, Idilbi, Kang, Vitev 3 D Parton Distributions 24

TMD evolution works: Drell-Yan and W/Z production • § Works for SIDIS, DY, and W/Z in all the energy ranges § Make predictions for future JLab 12, COMPASS, Fermilab, RHIC experiments LNF 1/12/2016 3 D Parton Distributions 25

The asymmetries • LNF 1/12/2016 3 D Parton Distributions 26

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Conclusions • The study of TMDs has entered the phase of multidimensional analysis • An important step in this direction is the large sample of precise unpolarised data, both as multiplicities and as azimuthal modulations • In the next years more of such data will be available both from COMPASS and from JLab 12 • Waiting for the EIC to extend the accessible phase space, the description of such data is a mandatory task for theory of TMDs LNF 1/12/2016 3 D Parton Distributions 30

Far Future perspective C EI e rag ve co COMPASS HERMES LNF 1/12/2016 3 D Parton Distributions 31

Thank you and see you all in Trieste for the EICUG meeting (July 18 -22, 2017)

The CM Energy vs Luminosity Landscape CEIC 1 = Chinese version of Electron-Ion Collider (“A dilution-free mini-COMPASS”) MEIC 1 = EIC@Jlab e. RHIC = EIC@BNL LHe. C = ep/e. A collider @ CERN CEIC 2 MEIC 2 HL-e. RHIC FCC-he LNF 1/12/2016 3 D Parton Distributions } 33