Crossed-channel Compton Crossed-channel Compton
Scattering Scattering
George – Catalin SERBANUT George – Catalin SERBANUT
Bad Honnef, May 28
Bad Honnef, May 28 th th , 2005 , 2005
Contents Contents
Brief theoretical overview Brief theoretical overview
CLEO/VENUS experiment CLEO/VENUS experiment
E760 experiment E760 experiment
E835 experiment E835 experiment
PANDA experiment PANDA experiment
Conclusions and outlook Conclusions and outlook
Introduction
Introduction
CCCS Overview
CCCS Overview
Wigner Distribution Wigner Distribution
) r , r ( ) e
2 (
r d )
2 (
r ) d
p ( n :
transform Fourier
) r ( ) r ( )
r , r ( :
matrix Density
2 1 /
) r r ( p i 3 2 3 3
1 3
2 1
* 2
1
2
1
R
2 r 1
, 2 R r 1
) e 2
(
R d )
2 (
r ) d
p ( n :
transform Fourier
2 R r 1
2 R r 1
2 R r 1
, 2 R r 1
: matrix Density
/ R p i 3 3 3
3
*
Wigner Distribution Wigner Distribution
2 R r 1 r , 2 R r 1
r
1
2
R
2 r 1 , 2 R r 1
) e 2 (
R d )
2 (
r ) d
p ( n :
transform Fourier
2 R r 1
2 R r 1
2 R r 1
, 2 R r 1
: matrix Density
/ R p i 3 3 3
3
*
) p , r ( ) W 2
( r ) d
p ( n : transform Fourier
) p , r ( W p d r
: matrix Density
2 R r 1 , 2 R r 1 ) e
2 (
R ) d
p , r ( W :
on distributi y
probabilit quasi
Wigner
3 3 3
/ R p i 3 3
Breit Frame & Fierz Transforms Breit Frame & Fierz Transforms
) m 4 /(
1 m E
E
2 / p
p 0
E E
0 p
p :
Definition Frame Breit
2 2
2 1
2 1
2 1
0
2
1
scalar pseudo
vector pseudo
tensor vector scalar 1
: ) ( Transform Fierz
5 5
and of
n combinatio
linear the
from only
arise
system Breit
the in transition
flip non
and flip
helicity
Form (Structure) Factors - Form (Structure) Factors -
Introduction Introduction
) p ( u ) ( M F
2 ) i
( F )
p ( u T ) T
' x x ( G ) 0 ( j
) 0 ( j
p
| ) 0 ( j
| p T
T
| T
| k
d
1 2
2 N 2
1 2
em fi fi
like int po
1 2
em fi fi
i f
2 fi f
' N 'l lN
Form (Structure) Factors - Form (Structure) Factors -
Introduction Introduction
e ( p ) p )
2 (
p
R d
3 ipr3
2 p 1 ) 0 ( 2 j
p 1 2 )
p 1 ( 2 )
p 1 ) (
2 (
p ) d
(
F
3 * 03
N N
N N
M
| p
|
|
| R
/ 1
| p
| / 1
| r
|
M / 1
| r
|
|
| / 1
| r
| R
| r
|
frame Breit
in density e
arg ch of element matrix
2 ) 1 0 ( 2 j
) 1 ( F M
2
N
0 )
p ( u ) (
G ) p ( u ) (
F
2 E
2 1) (
F ) (
F ) (
G
) (
M F ) 4
( F ) (
G
2 2
2 1 2
M
2 2 2
N 2 2
1 2
E
CCCS Specific Cross-Section CCCS Specific Cross-Section
N q N
q 1
1 q i q
i
p / p
; p / p x
P , A , V i for ) s , , x ( dx )
s ( F
P , A , V i for )
s ( F e R
q
q i 2 q
i
) v , v ( v
) v v 2( v 1
v , v , v v
: on quantizati cone
Light
2 1
3 0
Handbag Diagram
s tu sin 2
s u cos t
) s ( M R 4 ) s s ( R ) s ( R cos
) s ( sin R
1 s
4 dt
d 2
2 P N 2
P A
2 2 2 V
2 2 em
2
2 2
2 2
sin
) ( cos
) ( 4
cos
s R s
R s
d
d
em V
A2 2
2 2 2
cos 1
cos ln 1
cos 2 1 1
with cos
4
A V
eff
em Reff R R R
s
CLEO/VENUS Data CLEO/VENUS Data
2 A 2
V 2
eff 2
eff 2
em R
cos 1
cos ln1
cos 2 1 1 R R with cos R
s
4
4 eff
2
R ( s ) ( 6 . 5 0 . 5 ) GeV
s
5 2
s GeV 1 nb 25 . 7647 6
. 0
cos
s
2R
eff[ G eV
4]
s [GeV
2]
6 2
eff
~ s
dt
; d s
~ R : . const s
/
t
E760 Detector Layout
E760 Detector Layout
E760 Data
E760 Data
E760 Analysis E760 Analysis
% 96
~ 0
0
% 98
~ 0
p p
p p
p p
energy those
for even
respected is
law power s
' Brodsky the
: . const s
/ t
) s / t ( f s
~ )
dt / d ( : s
and fixed s
/ t
: law power s
' Brodsky
) ension dim space Fock ( 2 CD AB
E835 Detector Layout
E835 Detector Layout
PANDA Detector
PANDA Detector
Preliminary Analysis Preliminary Analysis
3.6 GeV
20 MeV
Preliminary Analysis Preliminary Analysis
3.6 GeV
50 MeV
Preliminary Analysis Preliminary Analysis
energy cut colinearity cut
2
2 2
2 2
sin
) ( cos
) ( 4
cos
s R s
R s
d
d
em V
A angular cut
relative loss = ratio between the number of events remained after applying the cuts and the number of generated events
quality = ratio between the number of good events and the total number of events
pb 17500 pb
420 pb
20 :
GeV 13
s
pp pp 0 pp 0 02
