Theory Castello di Trento (Trint), watercolor 19.8 x 27.7, painted - PowerPoint PPT Presentation

ECT* EUROPEAN CENTRE FOR THEORETICAL STUDIES IN NUCLEAR PHYSICS AND RELATED AREAS TRENTO, ITALY Institutional Member of the European Expert Committee NUPECC Theory Castello di Trento (“Trint”), watercolor 19.8 x 27.7, painted by A. Dürer on his way back from Venice (1495). British Museum, London Summary The Proton Mass: At the Heart of Most Visible Matter Trento, April 3 - 7, 2017 Main Topics Hadron mass decomposition in terms of constituents: Uniqueness of the decomposition, Quark mass, and quark and gluon energy contribution, Anomaly contribution, ... Hadron mass calculations: Lattice QCD (total & individual mass components), Approximated analytical methods, Phenomenological model approaches, ... Experimental access to hadron mass components: Exclusive heavy quarkonium production at threshold, nuclear gluonometry through polarized nuclear structure function, … Confjrmed keynote speakers Alexandrou Constantia ( Cyprus University ), Brodsky Stan ( SLAC ), Burkhardt Matthias ( New Mexico State University ), Camalich Jorge Martin ( CERN ), Chen Jian-Ping ( Jefferson Lab ), Chudakov Eugene ( Jefferson Lab ), Cloët Ian ( Argonne National Lab ), de Teramond Guy ( University Costa Rica ), Deshpande Abhay ( Stony Brook University ), Eichmann Gernot ( Giessen University ), Gao Haiyan ( Duke University ), Hafjdi Kawtar ( Argonne National Lab ), Hoelbling Christian ( University of Wuppertal ), Lin Huey-Wen ( Michigan State University ), Liu Keh-Fei ( University of Kentucky ), Lorcé Cédric ( École Polytechnique, Palaiseau ), Mulders Piet ( Vrije University of Amsterdam ), Papavassiliou Joannis ( Valencia University ), Pascalutsa Vladimir ( Johannes Gutenberg University of Mainz ), Peng Jen-Chieh ( University Illinois Urbana-Champaign ), Richards David ( Jefferson Lab ), Roberts Craig ( Argonne National Lab ), Barbara Pasquini / Marc Vanderhaeghen Scherer Stefan ( Johannes Gutenberg University of Mainz ), Slifer Karl (University of New Hampshire). Organizers Zein-Eddine Meziani ( Temple University ) Barbara Pasquini ( University of Pavia ) Jianwei Qiu ( Jefferson Lab ) Marc Vanderhaeghen ( Universität Mainz ) Director of the ECT* : Professor Jochen Wambach (ECT*) The ECT* is sponsored by the “Fondazione Bruno Kessler” in collaboration with the “Assessorato alla Cultura” (Provincia Autonoma di Trento), funding agencies of EU Member and Associated States and has the support of the Department of Physics of the University of Trento. For local organization please contact : Gianmaria Ziglio - ECT* Secretariat - Villa Tambosi - Strada delle Tabarelle 286 - 38123 Villazzano (Trento) - Italy Tel.:(+39-0461) 314721 Fax:(+39-0461) 314750, E-mail: ect@ectstar.eu or visit http://www.ectstar.eu

scales in QCD C. Roberts Ø Only apparent scale in chromodynamics is mass of the quark field Ø In connection with everyday matter, that mass is 1/250 th of the natural (empirical) scale for strong interactions, viz . more-than two orders-of-magnitude smaller Ø Quark mass is said to be generated by Higgs boson. Ø Plainly, however, that mass is very far removed from the natural scale for strongly-interacting matter Ø Nuclear physics mass-scale – 1 GeV – is an emergent feature of the Standard Model its absolute value is NOT explained by the Standard Model – No amount of staring at L QCD can reveal that scale Ø Contrast with quantum electrodynamics, e.g . spectrum of hydrogen levels measured in units of m e , which appears in L QED 2

Scales in strong interactions Simplicity Hot and dense quark-gluon matter Hadron structure Hadron-Nuclear interface Nuclear structure Nuclear reactions Resolution Nuclear astrophysics Applications of nuclear science Complexity 3

Scale invariance of QCD (classical) in absence of quark masses Theory is invariant under x → e λ x scale transforma=on s µ = T µ ν x ν Noether current dilata=on current: energy momentum tensor scale invariant theory: dilata=on current is conserved 0 = ∂ µ s µ = T µ µ Scale-invariant classical theory: energy-momentum tensor is traceless 4

Scale/trace anomaly in QCD Quantum loop correc=ons: running coupling -> dimensional transmuta=on β ( g ) = − b g 3 b = 11 − 2 16 π 2 + ..., 3 N f Quantum (loop) effects lead to a non-zero trace of energy-momentum tensor µ = β ( g ) αβ G a αβ + m h (1 + γ m h ) ¯ Q h ¯ X X T µ 2 g G a m l (1 + γ m l )¯ q l ¯ q l + Q h l = u,d,s h = c,b,t g 2 at low energies: Q h → − 2 αβ G a αβ + ... X m h ¯ Q h ¯ 32 π 2 G a 3 N h heavy quarks decouple h = c,b,t ˜ β ( g ) αβ G a αβ + X T µ 2 g G a µ = m l (1 + γ m l )¯ q l ¯ q l l = u,d,s 5

Mass of hadrons h P | T µ ν | P i = 2 P µ P ν ˜ β ( g ) 2 M 2 = h P | X 2 g G a αβ G a αβ | P i + h P | m l (1 + γ m l )¯ q l ¯ q l | P i l = u,d,s In chiral limit all of hadron mass Quark contribuEons to hadron is due to the trace anomaly mass: sigma-terms σ ud , σ s LaIce QCD, dispersion rela=ons, ChPT For pion: zero mass in chiral limit implies cancella=on between different components: dynamical chiral symmetry breaking C. Roberts Physics pictures (non-perturba=ve models) how hadron masses can be understood: Shed light on the non-trivial nature of bound state in QCD / confinement effec=ve degrees of freedom at hadronic scale / relevant symmetries, breaking paQerns - rela=vis=c bound states P. Hoyer - Holographic QCD S. Brodsky, G. de Teramond - Dyson-Schwinger Eq. D. Binosi, I. Cloët, J. Papavassiliou, C. Roberts - Rest frame decomposi=ons (e.g bag, soliton,…models) X. Ji - Partonic interpreta=ons C. Lorcé, L. Mantovani, M. Burkardt - Instanton liquid P. Faccioli 6

Models / Interpretations 7

Light quarks and confinement Understanding the origin and absence of mass in QCD likely inseparable from understanding of confinement C. Roberts G. Bali et al ., PoS LAT2005 (2006) 308 8

Continuum truncation: Dyson-Schwinger (I) D. Binosi, I. Cloët, J. Papavassiliou, C. Roberts QCD effec=ve charge: dynamical confinement: Coupling possesses IR fixed point massless gauge bosons acquire a mass (IR cut-off in QCD) 9

Continuum truncation: Dyson-Schwinger (II) D. Binosi, I. Cloët, J. Papavassiliou, C. Roberts pion exists if and only if mass is dynamically generated dynamical chiral symmetry breaking (quark-gluon dynamics): origin of mass PS Bethe-Salpeter amplitude in pseudo scalar channel: the dynamically generated mass of the two fermions is precisely cancelled by the aQrac=ve interac=ons between them 10

Continuum truncation: Dyson-Schwinger (III) I. Cloët, C. Roberts pion DA can be obtained as projec=on of pion’s Bethe-Salpeter amplitude onto light-front

Holographic QCD S.J. Brodsky, G. de Teramond 12

Holographic QCD S.J. Brodsky, G. de Teramond 13

Holographic QCD S.J. Brodsky, G. de Teramond supersymmetric and superconformal constraints on meson and baryon masses 14

Proton mass decompositions X. Ji, J.W. Qiu 15

Proton mass decompositions X. Ji, J.W. Qiu 16

Partonic interpretations C. Lorcé Parity-odd EMT Quark spin-orbit correlation Quark Spin Quark OAM Chiral-odd EMT Transverse spin-orbit correlations

Kinetic EMT Belinfante EMT EOM

Interpretation in scalar diquark model L. Mantovani in absence of gluons: Kinetic OAM = Jaffe-Manohar OAM

Quark OAM from Wigner distributions M. Burkardt Canonical Kinetic

What is known or can be learned from lattice QCD / phenomenology ? 21

Hadron masses (lattice) C. Alexandrou, C. Hoelbling, H.W. Lin, K.F. Liu, D. Richards, Y. Yang

Quark mass contributions (lattice) C. Alexandrou, C. Hoelbling, H.W. Lin, K.F. Liu, D. Richards, Y. Yang laIce calcula=ons at physical point (solid symbols) New preliminary BMW results: 23

Nucleon spin (lattice) C. Alexandrou Gluonic contribu=on calculated on laIce ! B g (0) = 0 X X h x i q ⇡ 2 J q q q 24

pion-nucleon 𝜏 -terms: ChPT J.M. Alarcon ~ 3 𝜏 tension between recent laIce and ChPT / DR 25

pion-nucleon 𝜏 -terms: dispersion theory J.Ruiz de Elvira 26

pion-nucleon 𝜏 -terms: ChPT J.M. Alarcon 27

Nucleon structure corrections to precision observables V. Pascalutsa forthcoming PSI 1 S-HFS measurement in H µ with 1 ppm accuracy Antognini(2016) l l γ γ X p p relative relative contribution uncertainty ( ✕ 10 -3 ) X=p (Zemach) -7,36 140 ppm X=p (recoil) 0,8476 0.8 ppm X=p, π N,… 0,363 86 ppm (polarizability) -6,149 total 164 ppm Carlson, Nazaryan, Griffioen(2011) Tomalak et al.(2016) 28

threshold photoproduction of J/ ψ on nucleons D. Kharzeev heavy quarkonium: color dipole interac=on with hadrons may be es=mated from its chromoelectric polarizability (QCD van der Waals force) - 2-gluon exchange - at very large distances: interac=on dominated by pions calculated from trace of energy momentum tensor θ µ µ Peskin (1979); Voloshin, Zakharov (1980); Fujii, Kharzeev (1999) quarkonium-proton interac=on at low energies probes distribu=on of mass in proton 29