N* Physics with CLAS and CLAS12 Ralf W. Gothe EMIN 2015 XIV International Seminar on Electromagnetic Interactions of Nuclei Moscow, October 5-10, 2015 NN* Vertexcouplings: A unique window into baryon and quark structure? Analysis and New Results: Phenomenological but consistent. Outlook: New experiments with extended scope and kinematics. QCD based Theory: Can we solve non-perturbative QCD and confinement? 1 Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 This work is in parts supported by the US National Science Foundation under the Grant PHY-1205782
Spectroscopy Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 2
Hadron Spectroscopy: Meson, Baryons, … Q C D Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 3
N and Excited Baryon States … Simon Capstick Orbital excitations (two distinct kinds in contrast to mesons) Radial excitations (also two kinds in contrast to mesons) Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 4
Quark Model Classification of N* Dietmar Menze Lowest Baryon Supermultiplets SU(6)xO(3) Symmetry Particle Data Group **** (56,3-) (70,3-) (20,3-) *** 3 ** + q³g D 13 (1520) S 11 (1535) (56,2+) (70,2+) (70,2-) + q³qq 7/2 2 5/2 3/2 + N-Meson 1/2 L 3q + … (70,1-) (20,1+) (56,1-) (70,1-) 5/2 1 3/2 1/2 (1232) (70,1-) (20,1-) - q 2 q Roper P 11 (1440) (56,0+) (56,0+) (70,0+) - … 0 3/2 1/2 N h h h h 0 1 2 3 (Mass) (1135 MeV) (1545 MeV) (1839 MeV) (2130 MeV) 1135 MeV 1545 MeV 1839MeV 2130 MeV Mass Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 5
Quark Model Classification of N* Dietmar Menze Lowest Baryon Supermultiplets SU(6)xO(3) Symmetry Particle Data Group **** (56,3-) (70,3-) (20,3-) *** 3 ** 2010 (56,2+) (70,2+) (70,2-) 7/2 2 5/2 3/2 1/2 L 3q (70,1-) (20,1+) (56,1-) (70,1-) 5/2 1 3/2 1/2 (70,1-) (20,1-) (56,0+) (56,0+) (70,0+) 0 3/2 1/2 N h h h h 0 1 2 3 (Mass) (1135 MeV) (1545 MeV) (1839 MeV) (2130 MeV) 1135 MeV 1545 MeV 1839MeV 2130 MeV Mass Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 6
Quark Model Classification of N* Dietmar Menze BnGa energy-dependent coupled-channel PWA of CLAS K + Λ and other data Lowest Baryon Supermultiplets SU(6)xO(3) Symmetry Particle Data Group **** (56,3-) (70,3-) (20,3-) *** 3 ** 2012 (56,2+) (70,2+) (70,2-) 7/2 2 5/2 3/2 1/2 L 3q (70,1-) (20,1+) (56,1-) (70,1-) 5/2 1 3/2 1/2 (70,1-) (20,1-) (56,0+) (56,0+) (70,0+) 0 3/2 1/2 N h h h h 0 1 2 3 (Mass) (1135 MeV) (1545 MeV) (1839 MeV) (2130 MeV) 1135 MeV 1545 MeV 1839MeV 2130 MeV Mass Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 7
Quark Model Classification of N* Dietmar Menze BnGa energy-dependent coupled-channel PWA of CLAS K + Λ and other data Lowest Baryon Supermultiplets SU(6)xO(3) Symmetry Particle Data Group **** (56,3-) (70,3-) (20,3-) *** 3 ** 2012 (56,2+) (70,2+) (70,2-) naive q 2 q 7/2 2 5/2 model 3/2 1/2 L 3q (70,1-) (20,1+) (56,1-) (70,1-) 5/2 1 3/2 1/2 (70,1-) (20,1-) (56,0+) (56,0+) (70,0+) 0 3/2 1/2 N h h h h 0 1 2 3 (Mass) (1135 MeV) (1545 MeV) (1839 MeV) (2130 MeV) 1135 MeV 1545 MeV 1839MeV 2130 MeV Mass Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 8
N/ Δ Spectrum in RPP 2012 High-statistics and high-precision photoproduction data from JLAB, MAMI, ELSA, GRAAL Are we observing parity Are we observing parity doublets with the new states? doublets with the new states? or not? V. Crede & W. Roberts, Rep. Prog. Phys. 76 (2013) Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 9
New FROST Results from p 0 p W = 1.650 GeV W = 1.920 GeV W = 2.170 GeV before fit after fit • FROST experiment produced 900 data points of the double-polarization observable E in π + photoproduction with circularly polarized beam on longitudinally polarized protons for W = 1240 - 2260 MeV. • Significant improvements of the description of the data in SAID, Jülich, and BnGa partial-wave analyses after fitting. New strong evidence found in this data for a ∆ (2200)7/2 - resonance (BnGa analysis). • S . Strauch et al. , arXiv:1503.05163 and A.V. Anisovich et al. , arXiv:1503.05774 Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 10
N* Spectrum in LQCD The strong interaction physics is encoded in the nucleon excitation spectrum that spans the degrees of freedom from meson-baryon and dressed quarks to elementary quarks and gluons. LQCD predicts states with the same quantum numbers as R. Edwards et al. CQMs with underlying SU(6)xO(3) symmetry. arXiv:1104.5152, 1201.2349 Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 11
N* Spectrum in LQCD The strong interaction physics is encoded in the nucleon excitation spectrum that spans the degrees of freedom from meson-baryon and dressed quarks to elementary quarks and gluons. LQCD predicts hybrid baryon states replicating the R. Edwards et al. negative parity multiplet structure. arXiv:1104.5152, 1201.2349 Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 12
Transition Form Factors Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 13
Hadron Structure with Electromagnetic Probes Study the structure of the nucleon spectrum in the domain Q 2 … where dressed quarks are the major active degree of freedom. low Explore the formation of excited nucleon states in interactions k of dressed quarks and their emergence from QCD. N,N * , * … 3q-core+MB-cloud K 2 N P 2 * 3q-core Q 2 K 2 K 1 N P 1 high pQCD Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 14
Hadron Structure with Electromagnetic Probes Study the structure of the nucleon spectrum in the domain Quark mass extrapolated to the chiral limit, where q Q 2 … where dressed quarks are the major active degree of freedom. is the momentum variable of the tree-level quark low Explore the formation of excited nucleon states in interactions propagator using the Asqtad action. q of dressed quarks and their emergence from QCD. N,N * , * … meson dressed quark LQCD, DSE and … 3q-core+MB-cloud confinement quark mass (GeV) 3q-core current quark e.m. probe high pQCD Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 15
Baryon Excitations and Quasi-Elastic Scattering hard and confined Elastic Form Factors Transition Form Factors hard soft Deep Inelastic Scattering S. Stein et al., PR D22 (1975) 1884 Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 16
Data-Driven Data Analyses Consistent Results QCD DSE N*, Δ * LQCD Single meson production: Single meson production: Unitary Isobar Model (UIM) Unitary Isobar Model (UIM) Fixed- t Dispersion Relations (DR) Fixed- t Dispersion Relations (DR) Double pion production: Double pion production: Amplitude Reaction analysis Models Unitarized Isobar Model (JM) Unitarized Isobar Model (JM) Coupled-Channel Approach: Coupled-Channel Approach: EBAC Argonne-Osaka EBAC Argonne-Osaka JAW Jülich-Athens-Washington JAW Jülich-Athens-Washington Data BoGa Bonn-Gatchina BoGa Bonn-Gatchina Hadronic Hadronic Electromagnetic Electromagnetic Int. J. Mod. Phys. E, Vol. 22, 1330015 (2013) 1-99 production production production production Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 17
Electrocouplings of N(1440)P 11 from CLAS Data 70 80 60 60 S 1/2 40 50 A 1/2 *1000 GeV S 1/2 *1000 GeV 20 40 0 30 -20 A 1/2 20 -40 -60 10 -80 0 0 1 2 3 4 0 1 2 3 4 Q GeV Q GeV N (UIM, DR) N (JM) preliminary N (JM) 2012 PDG Consistent results obtained in the low-lying resonance region by independent analyses in the exclusive N and p + - final-state channels – that have fundamentally different mechanisms for the nonresonant background – underscore the capability of the reaction models to extract reliable resonance electrocouplings. Phys. Rev. C 80, 055203 (2009) 1-22 and Phys. Rev. C 86, 035203 (2012) 1-22 Ralf W. Gothe EMIN 2015, Moscow, Russia October 5-10, 2015 18
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