Pion-Nucleon Charge Exchange in the N*(1440) Resonance Region

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Pion-Nucleon Charge Exchange in the N(1440)
Resonance Region

• Michael Sadler, Melissa Jerkins
• and Shon Watson
• Abilene Christian University
• For the Crystal Ball Collaboration

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Crystal Ball Collaboration at BNL
A. Barker (deceased), C. Bircher, C. Carter, M.
Daugherity, B. Draper, S. Hayden, J. Huddleston,
D. Isenhower, M. Jerkins, M. Joy, C. Robinson, M.
Sadler and S. Watson, Abilene Christian
University, C. Allgower, R. Cadman and H. Spinka,
Argonne National Laboratory, J. Comfort, K.
Craig and A. Ramirez, Arizona State
University, T. Kycia (deceased), Brookhaven
National Laboratory, M. Clajus, A. Marusic, S.
McDonald, B. M. K. Nefkens, N. Phaisangittisakul,
S. Prakhov, J. Price, A. Starostin and W. B.
Tippens, University of California at Los
Angeles, J. Peterson, University of Colorado, W.
Briscoe, A. Shafi and I. Strakovsky, George
Washington University, H. Staudenmaier,
Universität Karlsruhe, D. M. Manley and J.
Olmsted, Kent State University, D. Peaslee,
University of Maryland, V. Abaev, V. Bekrenev, N.
Kozlenko, S. Kruglov, A. Kulbardis, and I.
Lopatin, Petersburg Nuclear Physics Institute, N.
Knecht, G. Lolos and Z. Papandreou, University
of Regina, I. Supek and D. Mekterovic, Rudjer
Boskovic Institute, and D. Grosnick, D. D.
Koetke, R. Manweiler and S. Stanislaus,
Valparaiso University
Experiment Spokespersons Ph.D. Students (total
of 9)
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Crystal Ballmultiphoton spectrometer
672 NaI crystals.Individual PMTs 93 of 4p sr
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V. Bekrenev mounting PM tubes
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The Crystal Ball
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The Crystal Ball
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Crystal Ball layout in the C6 beam line at the
Brookhaven AGS
Crystal Ball layout in the C6 beam line at the
Brookhaven AGS
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Invariant Mass for neutral meson decay, e.g. p0
to 2g
g1
180
y
g2
lab frame
p0 rest frame
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Identification of Neutral Mesons from their
Invariant Mass
po
h
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Crystal Ball Data
Strange Spectroscopy
Non-strange Spectroscopy p- p ? pn p- p ?
ppn p- p ? pppn p- p ???n p- p ???n p- p
??p?n Neutron detection Nuclear Physics p- A ?
pX p- A ? ppX p- A ? ?X Eta
decays ????p?? ????ppp ????pp ????pppp
????pp? ????ppp? ??????? Antiprotons
??neutrals (p,????
Quantity of data 20 momenta for p-p 2
p-A 1 8
K-p 3107 hs
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153 MeV/c
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172 MeV/c
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185 MeV/c
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200 MeV/c
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218 MeV/c
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247 MeV/c
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267 MeV/c
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301 MeV/c
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320 MeV/c
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351 MeV/c
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378 MeV/c
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408 MeV/c
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456 MeV/c
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490 MeV/c
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532 MeV/c
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614 MeV/c
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658 MeV/c
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p-p ? p0n Overview
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p-p ? p0n excitation functions
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p-p ? p0n excitation functions
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p-p ? p0n excitation functions
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p-p ? p0n excitation functions
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p-p ? p0n excitation functions
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p-p ? p0n excitation functions
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Call for a new determination of the P11(1440)
resonance parameters

• Aliases for the lowest lying state with I
  1/2, JP 1/2
• N(1440)
• P11(1440)
• Roper resonance
• First excited state of the nucleon

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What do we learn from PWA?

• Input for??N ??term.
• Charge symmetry breaking.
• Resonance parameters (P11, S11, D13) masses,
  widths, decay modes.
• Interface between experiment and models.
• Quark models
• Skyrme models
• Collective models

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N(1440) summary in Review of Particle Physics
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N(1440) summary in Review of Particle Physics
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N(1440) summary in Review of Particle Physics
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Arndt, et al., Phys. Rev. C69, 035213 (2004).
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Arndt, et al., Phys. Rev. C69, 035213 (2004).
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Summary of Pion-Nucleon Reactions and Observables
Reactions Observables pp ? pp d?/d? p-p ?
p-p P (AN) p-p ? pon A and R p-p ? ?n p-p
? popon p-p ? ?n
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pN Experiments at LAMPF and BNL
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625 MeV/c pp
pp ? pp 625 MeV/c
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625 MeV/c p-p
p-p ? p-p 625 MeV/c
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625 MeV/c p-p ? p0n
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p- p Total Cross Section
1440
1440
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P11 (1440) speed plot from multichannel analysis
Speed dT/dW, where T elastic T-matrix
amplitude.
From D. M. Manley, Proc. of the Workshop on the
Physics of Excited Nucleons (NSTAR 2004), World
Scientific.
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p-p ? p0 p0nstot
1440
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p-p?p0 p0nDalitz plots
Crystal Ball Prakhov, et al. PRC 69, 045202 (2004)
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Summary of Present Status

• Listings in Review of Particle Properties rely on
  PWAs from 1980.
• GWU (formerly VPI) analyses fit data well, but
  not included in averages.
• Analyses should include pp-gtppN.
• PWA for hadronic channels is needed to analyze
  data from photo- and electro-production of
  resonances.
• No present experimental facilities for baryon
  spectroscopy (1-3 GeV/c ps, Ks).

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Beginnings of a new PWA effort, Abilene 2004
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Beginnings of a new PWA effort, Zagreb 2005
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Conclusions

• New PWA efforts are needed to determine
  properties of the P11(1440) resonance.
• Complete data sets now available.
• KH and CMB analyses completed in 1980.
• New PWAs can be extended to higher resonances
  when data become available from new facilities.
• MIPP at FNAL presents a new possibility (if
  eventually approved) to make measurements in the
  pN resonance region (1-3 GeV/c) and with kaon
  beams higher than 3 GeV/c.
• J-PARC (near Tokyo) is a future hadron facility.
  Call for new proposals is expected this year.
• An intermediate experiment on non-strange
  resonances near 1710 MeV is planned at ITEP
  (Moscow).