Baryon Spectroscopy at Jlab and J-PARC K. Hicks (Ohio U.) Baryons2013 Conference 24 June 2013

Physics of broad & overlapping resonances Δ (1232) Width: a few hundred MeV. Resonances are highly overlapped in energy except  (1232). →Complex PWA is necessary Width: ~10 keV to ~10 MeV Each resonance peak is clearly separated. N* : 1440, 1520, 1535, 1650, 1675, 1680,...  : 1600, 1620, 1700, 1750, 1900, … N* : 1440, 1520, 1535, 1650, 1675, 1680,...  : 1600, 1620, 1700, 1750, 1900, … From: H. Kamano, JAEA seminar 2

Decuplet Assignments (PDG) From  -scatt. database: all **** rated. Lots of missing states! Lack of K-scatt. data or photoproduction data. L=0 L=1 L=2 L=4 S 6/24/20133

Octet Assignments (PDG) L=0 L=1 L=2 Here, there are more assignments, but many have few-star ratings. Mass hierarchy problem with L=1, S=3/2 !! 6/24/2013

Capstick & Roberts (1993) Even 20 years ago, this problem was known! (Note: just N  PWA.) 6/24/20135

Experiment vs. Quark Model 6/24/20136 Source: PDG review

Goals of this Physics Understanding the spectrum of excited states of the nucleon leads to a deeper understanding of non-perturbative QCD. Similarly, the spectrum of excited states of the hydrogen atom led to advances in QM. My working hypothesis: The constituent quark model is a failure for excited states of the nucleon. Perhaps the reason is that the CQM does not include effects of the meson-baryon cloud. 6/24/20137

 (1405) Photoproduction at CLAS If the L(1405) were a single 3-quark resonance, then all three decays should be symmetric. However, if the resonance is dynamically generated, interference of poles with different isospin can occur R. Schumacher, Thursday 9:00 talk 6/24/20138

Drell-Yan: nucleon has pion cloud From: P. Reimer, arXiv: The Drell-Yan process measures the antiquark sea in the nucleon. The results show that there is an asymmetry to the u* and d* sea in the proton. The nucleon has an admixture of qqq(qq bar ). 6/24/2013 9

NΔ Transition Form Factor (G M ) from EBAC In the relativistic QM framework, the bare-core contribution is well described by the three-quark component of the wavefunction at high Q 2.  One third of G*M at low Q 2 is due to contributions from meson–baryon (MB) dressing: bare quark core Meson- Baryon Cloud Effect The area of Q2<7.0 GeV2 is far from pQCD domain B.Julia-Diaz et al., PRC 69, (2004) 6/24/201310

Dynamical Coupled-Channels model MB channels  N->  N Reaction Amplitude Resonance core meson cloud meson baryon Physical N*s will be a “mixture” of the two pictures: bare resonance core (from QM) B*  N 6/24/201311

Recent Lattice Calculations Note: Not real mass! Reference: J. Dudek et al.,, arXiv: /24/201312

Projection of N* to S L J 6/24/201313

A Tale of Two Labs Jefferson Lab and J-PARC share a common interest: to understand QCD. The combination of high-quality hadronic data with double-polarization photoproduction data is more powerful than either one alone. Of course, other labs also share this interest. It is becoming clear that both hadronic and photoproduction data are needed due to coupled-channels effects that naturally link them together. 6/24/201314

P 11 (1440) couplings from CLAS N  NN Light front models: I. Aznauryan S. Capstick hybrid P 11 (1440) Meson cloud effect 6/24/201315

CLAS: e p → e' p  +  - The BLUE dotted curve uses only the known resonances from the Particle Data Group. The RED solid curve includes an extra resonance not seen from the PWA of  N data alone. 6/24/201316

CLAS: Partial Wave Analysis A new P 13 resonance, much lower in mass than the quark model prediction, is necessary to fit the data. 6/24/

Importance of N  Decay 6/24/201318

What data do we need? For almost 40 years, there have been no new measurements on ( ,2  ) in the nucleon resonance region. For many years, elastic  N was good enough With precise new data on  N   N,  N at Jefferson Lab, Bonn and elsewhere, along with theory advances, it becomes clear that hadronic-beam data is also needed to properly interpret the photoproduction data. 6/24/201319

 -N Total Cross Sections 6/24/201320

 N Total Cross Sections Kamano et al., PRC 79, (2009). Dashed line: no channel coupling. 6/24/201321

The Primary Source of ( ,2  ) 6/24/201322

Complete ( ,2  ) Database M. Manley, Phys. Rev. D 30, 904 (1984). Total number of events! 6/24/

Mass Projections Note: the normalization of these data is not known. The total cross sections were used to set the vertical scale. The solid curves are the full calculation using only  N elastic data. The other curves do not include some coupled- channels effects. 6/24/201324

S31 F37 F35 P31 P33 D33 D35 S31 F37 F35 P31 P33 D33 D35 PRELIMINARY PRELIMINARY 6/24/201325

TCS M(π+ n) M(π+ π+) TCS M(π0 p) M(π+ p) M(π+ π0) Current model Refit F37 PWA keeping N*  πΔ off PRELIMINARY W W 6/24/201326

J-PARC Experiment 6/24/201327

K1.8 beamline with TPC 6/24/201328

Experimental Setup Hyp-TPC Spectrometer Hyp-TPC  - beam Superconducting Helmholtz Dipole magnet Measure ( ,2  ) in large acceptance TPC  - p→  +  - n,  0  - p  + p→  0  + p,  +  + n  +- beam ~ 1M/spill (p= GeV/c) Liquid-proton target Trigger: Two charged particles in hodoscope Hodoscope 6/24/201329

Hyp-TPC –P-10 gas –H-target in TPC –Gating grid wires –3-layer GEM Good performance at high beam rates –Pad size 2.5 x 9~13 mm : 30 layers 5045 pads in total  /K/p PID with dE/dx vs p  - beam ~600 Gating Grid GEM Pad plane Target holder 500φ 50φ B=1T -- ++ E=180V/cm n P-10 gas Liquid H target ionization Electron drift 6/24/201330

TPC prototype test results Beam test at RCNP (Nov.2011) Position resolution (B=0)  x =0.40mm  y = 0.55mm Hit position distortion <0.1mm Field wires Drift field Charged particle e 20cm Expected  p/p= 1-3% ( ,p) 6/24/201331

Expected statistics Total ( ,2  ) cross section : ~2 mb Pion beam rate : ~10 6 (per 6 second spill) 5cm thick Liquid Hydrogen target TPC acceptance of 50% Result: 200 events / spill Energy coverage: W=1.50 – 2.15 GeV 26 energy bins(  W=0.025) 20 angle bins 10K events / bin Result: 24M events in 45 shifts (2 months) 6/24/201332

Status of R&D TPC development –1 st prototype successful to confirm basic performance at high beam rate –Design for real size 2 nd prototype going on with electronics development Other R&D specially for P45 Liquid hydrogen target –to fit TPC target hole of ~ 5cm cylinder Trigger hodoscopes –Optimize segmentation 6/24/201333

General Summary The N* spectrum is a long-standing problem. Today, we know that dynamical coupled- channels calculations are needed. → Coupled channels requires hadronic data. → Many N* states couple to 2  decay. My opinion: without quality ( ,2  ) data, it is difficult to see how the N* spectrum can be extracted with PWA techniques. 6/24/201334

Backup slides 6/24/201335

Additional final state: KY data Data for K  and K  come for free Cross sections are smaller, but the final state is two-body, so less data are needed. These final states have two charged particles and hence will be part of the trigger. Data on  + p  K +  + are especially useful Only isospin 3/2 contributes:  resonances. Is the  (1600) the I=3/2 partner of the Roper? 6/24/201336