Overview of the Hall D program at Jlab

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Overview of the Hall D program at Jlab
Adam Szczepaniak Indiana University

• History
• Meson spectroscopy
• PWA and all that (basics)
• Exotics and theoretical expectations
• Current Status

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1998-03 1-2 meetings/year Cassel review PAC
reviews Inst. Plan Review NSAC recommendation Part
of the Strategic Plan
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Meson spectroscopy with emphasis on gluonic
excitation
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Why mesons ?
Simplest QCD states Lab for fundamental
symmetry tests Heavy QQ are non-relativistic Lig
ht meson are chiral eigenstates Beyond the quark
model glueballs, exotics Bridge between
QCD and the S-matrix theory
DcSB quark model
JPC 0--,0-,1-,2-, L
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Meson spectroscopy open issues
and a few well established excited states
largely needs to be rewritten !
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Factorization in peripheral production I
s/t ! 1
T(s,t)
b(t) sa(t)
L Rea(t)
Resonance (or bound state Ima0)
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II
p- p ! p0p0 n
Regge particle 4 point function
s/t,s/t1,s/M! 1
t,a
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Combined analysis of CERN-Krakow-Munich and E852
data
L.Lesniak at al.
good
bad
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p- p ! p-pp- p
E852 2003 Full sample
BNL (E852) ca 1985
Software/Hardware from past century is obsolete
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MANTRID
Modern amplitude analysis
AVIDD cluster (Analysis and Visualization of
Instrument-Driven Data)
2x208 2.4 GHz Pentium (IUB IUPUI)
Original E852rp exotic based on0.5M events Now
processing 10M
36-processor cluster with 1.6Tb of storage
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Anatomy of a Partial Wave Analysis
p- p ! p-pp- p
Step 1 - Reconstruction and Monte Carlo
M.C. data (150M)
50M
25M
Reconstruction and Kinematic Fitting
More Filters
Data (78M)
16M
9M
This involves several hours of M.C.generation
and staging of about 1TB ofdata to disk and
processing Time required about a weekPerhaps
re-done 2 or 3 times
Multiplepasses tounderstandcuts
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APS et al. Phy. Rev. Lett. (03)
M.Swat et al. Phy. Rev. D. (03)
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Neutral hp

• Neutral vs charged production
• C is a good quantum number
• ao and a2 are produced (helps with
  ambiguities)
• only one detector involved

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Assume BW resonance in all, M1,0, P-waves
p1(900 5GeV) emerges
Intensity in the weak P-waves is strongly
affected by the a2(1320), strong wave due to
acceptance corrections
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combine Regge description with chiral
constraints
M
sgtgtt,M
Chiral
Regge
t
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p- p ! hp- p
Results of coupled channel analysis of
p- p ! hp- p
D
D
P
S
P
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An Exotic Signal in 3p
Exotic Signal
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Lattice predictions
Theoretical expectations
Lacock Schilling

• JPC 1- lowest state
• Higher masses difficult to resolve
• Chiral extrapolations 100-200 MeV

AW Thomas, AS (01)
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Decays

• Normal widths !

In large NC same as for ordinary mesons O(1/NC)
T. Cohen (98)

• Unusual decay modes !

Isgur, Kokosy, Paton (85) Page, Swanson, AS (99)

• Low lying states expected
• below string breaking !

Juge, Kuti, Morningstar (99) Bali (00)
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gp vs pp data
Compare statistics and shapes
Condo93 g p -gt r0p n -gt p p-p n _at_ 19.3 GeV
Adams 93 (E852) p- p -gt r0p- p -gt p p-p p _at_ 18
GeV
SLAC
a2
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p1 ?
Events/50 MeV/c2
p2
a1
SLAC
BNL
4
1.0
2.5
2.0
1.5
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Quantum Numbers for Hybrid Mesons
Excited Flux Tube
Quarks
Hybrid Meson
like
like
So only parallel quark spins lead to exotic JPC
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M.Swat, AS
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Photo production enhances exotic mesons
Condo93
OPE
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Finding the Exotic Wave
Double-blind M. C. exercise
An exotic wave (JPC 1-) was generated at level
of 2.5 with 7 other waves. Events were smeared,
accepted, passed to PWA fitter.
Statistics shown here correspondto a few days of
running.
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Detector
Lead Glass Detector
Barrel Calorimeter
This project was reviewedby the Cassel Committee
that endorsed the physics and technique. They
described the search as definitive and JLab
unique for this search.
Solenoid
Coherent Bremsstrahlung Photon Beam
Time of Flight
Note that tagger is 80 m upstream of detector
Tracking
Cerenkov Counter
Target
Electron Beam from CEBAF
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How GlueX Fares Compared to Existing Data
We will use for comparison the yields for
production of the well-established and
understood a2 meson
The GlueX numbers are based on 1 year of
low-intensity running at107 photon/sec. The
exotic meson yield is based on model
calculations. But even if the exotic were to be
produced at the suppressed ratewith p beams - we
would still see 250,000 exotic mesons !
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Experiment/Theory Collaboration
From the very start of the GlueX
collaboration, theorists have worked closely with
experimentalists on the design of the experiment,
analysis issues and plans for extracting and
interpreting physics from the data.
The PWA formalism is being developed with the
goal of understanding how to minimize biases and
systematic errors due to dynamical uncertainties
- e.g. overlap of meson and baryon resonance
production.
Lattice QCD and model calculations of the
hybrid spectrum and decay modes will guide the
experimental search priorities. The Lattice QCD
group computers at JLab will move into 10
Teraflop operations in 2005 - in time to impact
GlueX planning.