Hadron 2011 The Future of Hadrons Chris Quigg Fermilab
Hadron 2011 The Future of Hadrons: The Nexus of Subatomic Physics Chris Quigg Fermilab
Impressions . . . Enormous diversity and reach of experimental programs (insights from unexpected quarters) Remarkable progress in theory; emergence of LQCD (insights from unexpected quarters) Many puzzles, opportunities; much work to do Still “simple” questions that we cannot answer Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 1 / 41
Impressions . . . Enormous diversity and reach of experimental programs (insights from unexpected quarters) Remarkable progress in theory; emergence of LQCD (insights from unexpected quarters) Many puzzles, opportunities; much work to do Still “simple” questions that we cannot answer Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 1 / 41
Impressions . . . Enormous diversity and reach of experimental programs (insights from unexpected quarters) Remarkable progress in theory; emergence of LQCD (insights from unexpected quarters) Many puzzles, opportunities; much work to do Still “simple” questions that we cannot answer Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 1 / 41
Impressions . . . Enormous diversity and reach of experimental programs (insights from unexpected quarters) Remarkable progress in theory; emergence of LQCD (insights from unexpected quarters) Many puzzles, opportunities; much work to do Still “simple” questions that we cannot answer Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 1 / 41
Musings . . . Value of integration across hadronic physics Connect with the rest of subatomic physics (look for insights from unexpected quarters) You may answer questions that seem far afield Look beyond nuclear and particle physics Seek new ways to address hadronic questions How are we prisoners of conventional thinking? Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 2 / 41
Musings . . . Value of integration across hadronic physics Connect with the rest of subatomic physics (look for insights from unexpected quarters) You may answer questions that seem far afield Look beyond nuclear and particle physics Seek new ways to address hadronic questions How are we prisoners of conventional thinking? Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 2 / 41
Musings . . . Value of integration across hadronic physics Connect with the rest of subatomic physics (look for insights from unexpected quarters) You may answer questions that seem far afield Look beyond nuclear and particle physics Seek new ways to address hadronic questions How are we prisoners of conventional thinking? Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 2 / 41
Musings . . . Value of integration across hadronic physics Connect with the rest of subatomic physics (look for insights from unexpected quarters) You may answer questions that seem far afield Look beyond nuclear and particle physics Seek new ways to address hadronic questions How are we prisoners of conventional thinking? Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 2 / 41
Musings . . . Value of integration across hadronic physics Connect with the rest of subatomic physics (look for insights from unexpected quarters) You may answer questions that seem far afield Look beyond nuclear and particle physics Seek new ways to address hadronic questions How are we prisoners of conventional thinking? Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 2 / 41
Learning from History In contrast to biological evolution, unsuccessful lines in theoretical physics do not become extinguished, never to rise again. We are free to borrow potent ideas from the past and to apply them in new settings, to powerful effect. Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 3 / 41
Learning from History In contrast to biological evolution, unsuccessful lines in theoretical physics do not become extinguished, never to rise again. We are free to borrow potent ideas from the past and to apply them in new settings, to powerful effect. S -matrix style unitarity for multiparton amplitudes Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 3 / 41
Learning from History In contrast to biological evolution, unsuccessful lines in theoretical physics do not become extinguished, never to rise again. We are free to borrow potent ideas from the past and to apply them in new settings, to powerful effect. S -matrix style unitarity for multiparton amplitudes ? Multi-Regge analysis ? . . . if predictions unsuccessful, why? Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 3 / 41
Our picture of matter < 10 18 m) quarks and leptons Pointlike ( r ∼ t R n 3 m R n 2 e R n 1 b R t R s R c R d R n 3 n 2 u R n 1 t L m L e L t L c L u L b L s L d L Interactions: SU(3) c ⊗ SU(2) L ⊗ U(1) Y gauge symmetries Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 4 / 41
QCD: the basis of hadronic physics Fundamental fields: quarks and gluons, manifest in Proton structure [high resolution, hard scattering Matter at high density Lattice calculations Effective degrees of freedom, manifest in Constituent quarks, Goldstone bosons, . . . Effective field theories Isobar (resonance) models Nuclei and nuclear structure Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 5 / 41
QCD: the basis of hadronic physics Fundamental fields: quarks and gluons, manifest in Proton structure [high resolution, hard scattering Matter at high density Lattice calculations Effective degrees of freedom, manifest in Constituent quarks, Goldstone bosons, . . . Effective field theories Isobar (resonance) models Nuclei and nuclear structure Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 5 / 41
Asymptotic Freedom 11 10 9 8 7 6 1/ α s 5 4 3 2 1 10 0 10 1 10 2 10 3 Q [GeV] Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 6 / 41
Asymptotic Freedom 11 10 9 8 7 6 1/ α s 5 4 1 /α s (2 m c ) ≡ 27 � 2 m c � 3 6 π ln Λ 2 1 10 0 10 1 10 2 10 3 Q [GeV] Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 6 / 41
Insight from QCD: M p = E 0 / c 2 M p = C · Λ + . . . ≪ M p New kind of matter: mass � = sum of parts 3 · 1 2 ( m u + m d ) ≈ 10 ± 2 MeV J¨ uttner Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 7 / 41
Insight from QCD: M p = E 0 / c 2 M p = C · Λ + . . . ≪ M p New kind of matter: mass � = sum of parts 3 · 1 2 ( m u + m d ) ≈ 10 ± 2 MeV J¨ uttner 2000 BMW; cf. Ryan, Zanotti, Edwards O X * 1500 S * X M[MeV] D S L 1000 N r K* experiment 500 K width QCD p 0 Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 7 / 41
Influence of the fermion spectrum: M p ∝ m 2 / 27 t ❊ 1/ α U 2m t ’ 21/6 π 2m b 23/6 π “1/ α s ” 2m t 2m c 25/6 π 27/6 π M U “log(E)” Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 8 / 41
Unified theories: SU(5) Unification of Forces? 60 U(1) Y SU(2) L 40 1 /α 20 SU(3) c 0 5 10 15 � E � log 10 1 GeV Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 9 / 41
Unified theories: SU(5) + light SUSY Unification of Forces? 60 U(1) Y SU(2) L 40 1 /α 20 SU(3) c 0 5 10 15 � E � log 10 1 GeV Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 10 / 41
Unified theories: SU(5) + light SUSY 14 SM: 7/2 13 s 12 1/ MSSM: 3/2 11 10 2.5 3.0 3.5 4.0 log(Q [GeV]) Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 11 / 41
Toward Controlled Approximations ✄ NRQCD for heavy-heavy systems ( Q 1 ¯ Q 2 ) m Q i ≫ Λ QCD expansion parameter v / c ✄ HQET for heavy-light systems ( Q ¯ q ) q = � m Q ≫ Λ QCD ; � L + � s q expansion parameter Λ QCD / M Q ✄ Chiral symmetry for light quarks ( q 1 ¯ q 2 ) m q i ≪ Λ QCD expansion parameter Λ QCD / 4 π f π ✄ Lattice QCD Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 12 / 41
What is a proton? (For hard scattering) a broad-band, unseparated beam of quarks, antiquarks, gluons, & perhaps other constituents, characterized by parton densities f ( a ) ( x a , Q 2 ), i . . . number density of species i with momentum fraction x a of hadron a seen by probe with resolving power Q 2 . Q 2 evolution given by QCD perturbation theory f ( a ) ( x a , Q 2 0 ): nonperturbative i Historically: No correlations, only longitudinal d.o.f. Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 13 / 41
Beyond traditional parton distributions GPDFs, TMDs, 3-d images, . . . Anselmino, Aschenauer, Pretz γ ∗ → γ probes q ; γ → V probes g in ⊥ plane Compare impact-parameter distributions from pp → pp ? Chris Quigg (FNAL) The Future of Hadrons Hadron 2011 · June 17, 2011 14 / 41
Recommend
More recommend
