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1
Friday Afternoon Journal Club
ldquoVector-Meson Production by Polarized Photons at 28 47 and 93 GeVrdquo PRD 7 3150 (1973)
D Mack (TJNAF)61215
2
some context
3
The SLAC Polarized Gamma Facility
bullA polarized photon beam for the SLAC 82-inch hydrogen bubble chamber CK Sinclair (Tufts U) JJ Murray PR Klein (Stanford U Phys Dept) M Rabin (UC Berkeley) 1969 Published in IEEE TransNuclSci 16 (1969) 1065-1068 DOI 101109TNS19694325441 Presented at Conference C69-03-05 Proceedings References | BibTeX | LaTeX(US) | LaTeX(EU) | Harvmac | EndNote bullFull-text at JACoW Server
E Ruby Laser
E Primary e-
E Backscatt
Gamma
Polarization
178 eV 12 GeV 28 GeV 93
178 eV 16 GeV 47 Gev 91
2x178 eV 19 GeV 93 GeV 77
bull Mono-energetic (if broad) gamma beam with high linear polarization
bull 93 GeV was their technical limit they had to use a frequency doubling xtal and push the accelerator energy
bull 82rdquo LH2 bubble chamber detection (hence no photons observed π0 by Mx only)
10 μrad collimation
4
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
5
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
ZPC 33 407-417 (1987)
4π
6
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
61215Mack
PRD 7 3150 (1973)
π+π-
π+π-π0 K+K-
ZPC 33 407-417 (1987)
4π
Other than for didactic purposes I thought this paper (thanks Justin) might suggest
early contributions GlueX could make near 93 GeV
eg the ndasht dependence of the asymmetry
7
Forward Light Meson Photoproduction Xsects at 93 GeV
π+π- (rho) π+π-π0 (omega)
k+k- (phi) ppbar eta0
5
10
15
Cros
s Sec
tion
(micr
obar
ns)
ρ ω φ p-pbar η
Values from compilation byAR Dzierba
GlueX-doc-835-v1
These are big signals
up to 10 of the ~125 μbarn total hadronic xsect at
this energy
But is there low-hanging fruit for an early GlueX
publication
8
on to the paper
9
ρ γ + p p + π+π-
Fig 3a
10
ρrsquo misc
This 1973 work didnrsquot have much sensitivity
The 1984 paper Matt covered last time had higher statistics around M2π ~ 15 and suggested something was going on (I wonder if they made a plot like that on the right)
The 1987 suggested paper by Ryan found two resonances with the best signatures in 4π
11
ω γ + p p + π+π- (π0)π0
ω
ηGlueX
η
ω
φ ρΔ etc
Statistics on xsect and asymmetry look scruffy near 93 GeV Is this M Staibrsquos thesis
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
2
some context
3
The SLAC Polarized Gamma Facility
bullA polarized photon beam for the SLAC 82-inch hydrogen bubble chamber CK Sinclair (Tufts U) JJ Murray PR Klein (Stanford U Phys Dept) M Rabin (UC Berkeley) 1969 Published in IEEE TransNuclSci 16 (1969) 1065-1068 DOI 101109TNS19694325441 Presented at Conference C69-03-05 Proceedings References | BibTeX | LaTeX(US) | LaTeX(EU) | Harvmac | EndNote bullFull-text at JACoW Server
E Ruby Laser
E Primary e-
E Backscatt
Gamma
Polarization
178 eV 12 GeV 28 GeV 93
178 eV 16 GeV 47 Gev 91
2x178 eV 19 GeV 93 GeV 77
bull Mono-energetic (if broad) gamma beam with high linear polarization
bull 93 GeV was their technical limit they had to use a frequency doubling xtal and push the accelerator energy
bull 82rdquo LH2 bubble chamber detection (hence no photons observed π0 by Mx only)
10 μrad collimation
4
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
5
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
ZPC 33 407-417 (1987)
4π
6
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
61215Mack
PRD 7 3150 (1973)
π+π-
π+π-π0 K+K-
ZPC 33 407-417 (1987)
4π
Other than for didactic purposes I thought this paper (thanks Justin) might suggest
early contributions GlueX could make near 93 GeV
eg the ndasht dependence of the asymmetry
7
Forward Light Meson Photoproduction Xsects at 93 GeV
π+π- (rho) π+π-π0 (omega)
k+k- (phi) ppbar eta0
5
10
15
Cros
s Sec
tion
(micr
obar
ns)
ρ ω φ p-pbar η
Values from compilation byAR Dzierba
GlueX-doc-835-v1
These are big signals
up to 10 of the ~125 μbarn total hadronic xsect at
this energy
But is there low-hanging fruit for an early GlueX
publication
8
on to the paper
9
ρ γ + p p + π+π-
Fig 3a
10
ρrsquo misc
This 1973 work didnrsquot have much sensitivity
The 1984 paper Matt covered last time had higher statistics around M2π ~ 15 and suggested something was going on (I wonder if they made a plot like that on the right)
The 1987 suggested paper by Ryan found two resonances with the best signatures in 4π
11
ω γ + p p + π+π- (π0)π0
ω
ηGlueX
η
ω
φ ρΔ etc
Statistics on xsect and asymmetry look scruffy near 93 GeV Is this M Staibrsquos thesis
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
3
The SLAC Polarized Gamma Facility
bullA polarized photon beam for the SLAC 82-inch hydrogen bubble chamber CK Sinclair (Tufts U) JJ Murray PR Klein (Stanford U Phys Dept) M Rabin (UC Berkeley) 1969 Published in IEEE TransNuclSci 16 (1969) 1065-1068 DOI 101109TNS19694325441 Presented at Conference C69-03-05 Proceedings References | BibTeX | LaTeX(US) | LaTeX(EU) | Harvmac | EndNote bullFull-text at JACoW Server
E Ruby Laser
E Primary e-
E Backscatt
Gamma
Polarization
178 eV 12 GeV 28 GeV 93
178 eV 16 GeV 47 Gev 91
2x178 eV 19 GeV 93 GeV 77
bull Mono-energetic (if broad) gamma beam with high linear polarization
bull 93 GeV was their technical limit they had to use a frequency doubling xtal and push the accelerator energy
bull 82rdquo LH2 bubble chamber detection (hence no photons observed π0 by Mx only)
10 μrad collimation
4
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
5
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
ZPC 33 407-417 (1987)
4π
6
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
61215Mack
PRD 7 3150 (1973)
π+π-
π+π-π0 K+K-
ZPC 33 407-417 (1987)
4π
Other than for didactic purposes I thought this paper (thanks Justin) might suggest
early contributions GlueX could make near 93 GeV
eg the ndasht dependence of the asymmetry
7
Forward Light Meson Photoproduction Xsects at 93 GeV
π+π- (rho) π+π-π0 (omega)
k+k- (phi) ppbar eta0
5
10
15
Cros
s Sec
tion
(micr
obar
ns)
ρ ω φ p-pbar η
Values from compilation byAR Dzierba
GlueX-doc-835-v1
These are big signals
up to 10 of the ~125 μbarn total hadronic xsect at
this energy
But is there low-hanging fruit for an early GlueX
publication
8
on to the paper
9
ρ γ + p p + π+π-
Fig 3a
10
ρrsquo misc
This 1973 work didnrsquot have much sensitivity
The 1984 paper Matt covered last time had higher statistics around M2π ~ 15 and suggested something was going on (I wonder if they made a plot like that on the right)
The 1987 suggested paper by Ryan found two resonances with the best signatures in 4π
11
ω γ + p p + π+π- (π0)π0
ω
ηGlueX
η
ω
φ ρΔ etc
Statistics on xsect and asymmetry look scruffy near 93 GeV Is this M Staibrsquos thesis
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
4
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
5
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
ZPC 33 407-417 (1987)
4π
6
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
61215Mack
PRD 7 3150 (1973)
π+π-
π+π-π0 K+K-
ZPC 33 407-417 (1987)
4π
Other than for didactic purposes I thought this paper (thanks Justin) might suggest
early contributions GlueX could make near 93 GeV
eg the ndasht dependence of the asymmetry
7
Forward Light Meson Photoproduction Xsects at 93 GeV
π+π- (rho) π+π-π0 (omega)
k+k- (phi) ppbar eta0
5
10
15
Cros
s Sec
tion
(micr
obar
ns)
ρ ω φ p-pbar η
Values from compilation byAR Dzierba
GlueX-doc-835-v1
These are big signals
up to 10 of the ~125 μbarn total hadronic xsect at
this energy
But is there low-hanging fruit for an early GlueX
publication
8
on to the paper
9
ρ γ + p p + π+π-
Fig 3a
10
ρrsquo misc
This 1973 work didnrsquot have much sensitivity
The 1984 paper Matt covered last time had higher statistics around M2π ~ 15 and suggested something was going on (I wonder if they made a plot like that on the right)
The 1987 suggested paper by Ryan found two resonances with the best signatures in 4π
11
ω γ + p p + π+π- (π0)π0
ω
ηGlueX
η
ω
φ ρΔ etc
Statistics on xsect and asymmetry look scruffy near 93 GeV Is this M Staibrsquos thesis
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
5
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
ZPC 33 407-417 (1987)
4π
6
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
61215Mack
PRD 7 3150 (1973)
π+π-
π+π-π0 K+K-
ZPC 33 407-417 (1987)
4π
Other than for didactic purposes I thought this paper (thanks Justin) might suggest
early contributions GlueX could make near 93 GeV
eg the ndasht dependence of the asymmetry
7
Forward Light Meson Photoproduction Xsects at 93 GeV
π+π- (rho) π+π-π0 (omega)
k+k- (phi) ppbar eta0
5
10
15
Cros
s Sec
tion
(micr
obar
ns)
ρ ω φ p-pbar η
Values from compilation byAR Dzierba
GlueX-doc-835-v1
These are big signals
up to 10 of the ~125 μbarn total hadronic xsect at
this energy
But is there low-hanging fruit for an early GlueX
publication
8
on to the paper
9
ρ γ + p p + π+π-
Fig 3a
10
ρrsquo misc
This 1973 work didnrsquot have much sensitivity
The 1984 paper Matt covered last time had higher statistics around M2π ~ 15 and suggested something was going on (I wonder if they made a plot like that on the right)
The 1987 suggested paper by Ryan found two resonances with the best signatures in 4π
11
ω γ + p p + π+π- (π0)π0
ω
ηGlueX
η
ω
φ ρΔ etc
Statistics on xsect and asymmetry look scruffy near 93 GeV Is this M Staibrsquos thesis
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
6
Where This Talk (Sort of) Fits InDateLead
Paper
Supple-mental Paper
ρ(770) ω(782) φ(1020) Excited ρrsquos
Etc
52915Shepherd
PRL 53 751 (1984)
PRL 103 231801 (2009)
π+π-
61215Mack
PRD 7 3150 (1973)
π+π-
π+π-π0 K+K-
ZPC 33 407-417 (1987)
4π
Other than for didactic purposes I thought this paper (thanks Justin) might suggest
early contributions GlueX could make near 93 GeV
eg the ndasht dependence of the asymmetry
7
Forward Light Meson Photoproduction Xsects at 93 GeV
π+π- (rho) π+π-π0 (omega)
k+k- (phi) ppbar eta0
5
10
15
Cros
s Sec
tion
(micr
obar
ns)
ρ ω φ p-pbar η
Values from compilation byAR Dzierba
GlueX-doc-835-v1
These are big signals
up to 10 of the ~125 μbarn total hadronic xsect at
this energy
But is there low-hanging fruit for an early GlueX
publication
8
on to the paper
9
ρ γ + p p + π+π-
Fig 3a
10
ρrsquo misc
This 1973 work didnrsquot have much sensitivity
The 1984 paper Matt covered last time had higher statistics around M2π ~ 15 and suggested something was going on (I wonder if they made a plot like that on the right)
The 1987 suggested paper by Ryan found two resonances with the best signatures in 4π
11
ω γ + p p + π+π- (π0)π0
ω
ηGlueX
η
ω
φ ρΔ etc
Statistics on xsect and asymmetry look scruffy near 93 GeV Is this M Staibrsquos thesis
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
7
Forward Light Meson Photoproduction Xsects at 93 GeV
π+π- (rho) π+π-π0 (omega)
k+k- (phi) ppbar eta0
5
10
15
Cros
s Sec
tion
(micr
obar
ns)
ρ ω φ p-pbar η
Values from compilation byAR Dzierba
GlueX-doc-835-v1
These are big signals
up to 10 of the ~125 μbarn total hadronic xsect at
this energy
But is there low-hanging fruit for an early GlueX
publication
8
on to the paper
9
ρ γ + p p + π+π-
Fig 3a
10
ρrsquo misc
This 1973 work didnrsquot have much sensitivity
The 1984 paper Matt covered last time had higher statistics around M2π ~ 15 and suggested something was going on (I wonder if they made a plot like that on the right)
The 1987 suggested paper by Ryan found two resonances with the best signatures in 4π
11
ω γ + p p + π+π- (π0)π0
ω
ηGlueX
η
ω
φ ρΔ etc
Statistics on xsect and asymmetry look scruffy near 93 GeV Is this M Staibrsquos thesis
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
8
on to the paper
9
ρ γ + p p + π+π-
Fig 3a
10
ρrsquo misc
This 1973 work didnrsquot have much sensitivity
The 1984 paper Matt covered last time had higher statistics around M2π ~ 15 and suggested something was going on (I wonder if they made a plot like that on the right)
The 1987 suggested paper by Ryan found two resonances with the best signatures in 4π
11
ω γ + p p + π+π- (π0)π0
ω
ηGlueX
η
ω
φ ρΔ etc
Statistics on xsect and asymmetry look scruffy near 93 GeV Is this M Staibrsquos thesis
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
9
ρ γ + p p + π+π-
Fig 3a
10
ρrsquo misc
This 1973 work didnrsquot have much sensitivity
The 1984 paper Matt covered last time had higher statistics around M2π ~ 15 and suggested something was going on (I wonder if they made a plot like that on the right)
The 1987 suggested paper by Ryan found two resonances with the best signatures in 4π
11
ω γ + p p + π+π- (π0)π0
ω
ηGlueX
η
ω
φ ρΔ etc
Statistics on xsect and asymmetry look scruffy near 93 GeV Is this M Staibrsquos thesis
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
10
ρrsquo misc
This 1973 work didnrsquot have much sensitivity
The 1984 paper Matt covered last time had higher statistics around M2π ~ 15 and suggested something was going on (I wonder if they made a plot like that on the right)
The 1987 suggested paper by Ryan found two resonances with the best signatures in 4π
11
ω γ + p p + π+π- (π0)π0
ω
ηGlueX
η
ω
φ ρΔ etc
Statistics on xsect and asymmetry look scruffy near 93 GeV Is this M Staibrsquos thesis
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
11
ω γ + p p + π+π- (π0)π0
ω
ηGlueX
η
ω
φ ρΔ etc
Statistics on xsect and asymmetry look scruffy near 93 GeV Is this M Staibrsquos thesis
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
12
ωrsquo misc
Focus on highest beam energy a la GlueX
bull the lower ndashtmin makes production by t-channel exchange more efficient
bull plus better separation of current and target fragments (next slide)
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
13
Overlap of Current and Target Fragments in γ + p p + π+π-π0
AR Dzierba GlueX-doc-838-v4
There are similar backgrounds for bull ρ photoproduction γ+pΔ++π- pπ+ π- and possibly bull φ photoproduction γ+pΛ(1520)K+ pK- K+ (see Fig 4 of Anciant et al paper)Looks small for η photoproduction but it might be important in a precision η3π Dalitz distribution like we hope to measure
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
14
ldquoPhirdquo γ + p p + K+K-
High statistics φ xsects
exist (from a different
expt)
Statistics was very
thin on the
asymmetry
Presumably therersquos been no change near 93
GeV
If this is low-
hanging fruit
whatrsquos the physics
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
15
CLAS Paper from 2000
E Anciant et al PhysRevLett854682-46862000
Phi photoproduction at large ndasht is supposed to be easier to model than rho or omega due to suppression of quark exchange with the target
CLAS saw interesting deviations in the xsect above ~ 2 GeV2 suggesting 2-gluon exchange (See also K McCormick et al httpjournalsapsorgprcabstract101103PhysRevC69032203 which used the same 2-gluon exchange model)
Itrsquos conceivable the asymmetry might show interesting evolution as low as ndasht ~ 1 GeV2
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
16
Xsect ~ b12 + b2
2 + b32 + b4
2
Σ ~ b12 + b2
2 - b32 - b4
2
PERHAPS the asymmetry for φ
photoproduction would make a stronger case
for the two-gluon exchange
Reinhardrsquos slide from the Userrsquos Group meeting
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
17
end
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η
18
Exclusive γ + p p + π+π-π0
Data figures by J Stevens
Completed calibrations should result in a well-isolated η peak
(above)
Simulations
ω π+π- π0 combines charged particle and photon reconstruction (xsect still large but 10x smaller than ρ)
Calibrations now good enough to see a hint of η3π
ω
η
Data
ω
φ
η