BARTON - Brookhaven National Laboratory — a passion … DYCS P = Gg Fq a L f s.. 1 3. 'ac 3 .3 4 3...
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Transcript of BARTON - Brookhaven National Laboratory — a passion … DYCS P = Gg Fq a L f s.. 1 3. 'ac 3 .3 4 3...
I
BARTON
P ?
Y 4 /<
9 f
P L
q+ ; q- LARC
P
t-
t 2sd GRAQH
XFa D Y C S P = Gg
Fq a
L
1 f s..
3.
'ac
3 .3
4
3
.. .
4 = i-9
F-
1 5. T f
I b LI
‘-5
I
1-5 b
-cI
3 e =o
I * [dx x -I
I
J d u x -I
\ D E r n T Y :
4f2 cyt)
0 311's suy RULE : Jq
2 ' 0
.. ..
i ..
. . -. . - . .. -. . . - - . - ..-. -... --.-. .. __ ...... __ .
H u - d Y El,
c9
0.4
0.3
0.2
0.1
0 0 1 2 3
-t [GeV2]
0.2
0
-0.2
-0.4 0 1 2 . 3
-t [GeV2]
0.05
0
-0.05
-0.1
-0.15 0 1 2 3
-t [GeV2]
M Gijckeler et al, QCDSF Collaboration, hepph/0304249
I 0
J = L9 Aq(o) c Bq(o) J - 2 I
2
Lk-4 = - 0.16 ( 3 )
6
rJ
0 \N E Y - g d
14.0
9.0
4.0
-1 .o
-6.0
I I
I I I
- A2= -0.5 Gev?
-- A2=-1. Gev? ----. -”-._ A2 = -0.7 Gef E = 0.2 Tc
POLE 7
10
5 -
0
-5
I I I - A2= -0.5 GeV2 A2= -0.7 GeV2 -- 5 = 0.2
___--_-___ A2= -1 GeV2 -
I t I
Figure 4: values of A2 and t. The positive curves correspond to pion pole contributions.
Comparison of pion pole contribution and non-pole part of isovector at various
1 -0.5 0 X
-1 0.5
-1 -0.5 0 0.5 1 X
1
0.8
0.6
0.4
0.2
0
3 = 0 . 5
t f - 0.35 GrVL
-1 -0.5 0 0.5 1 X
from: K Goeke, M V Polyakov and M Vanderhaeghen, hepph/0106012
--
I
b
e
Idr -_.
DVCS
n RIGHT-
L + - 3 I 9 9 9
-c- J V C S
Qb, f
h)
4- 'hat f"'
f , . , , .....
lqESOpCS :
NB I
t
---x V
'".\, ,/- gvcs k/
P
IO II
8
6
H1 p production I I f l I 1 1 I l l 1 1 I 1
t SCHC approximation
I * H1 meliminary i J.
0 H1
ZEUS
t
t 4
t
2 F
0
i
n - k - Martin, Ryskin, Teubner
I l l I I I 1 1 I I I I I l l I l l I
0 10 20 30 40 n
10
8
6
4
2
Elastic VM production
I !
Hl p prel.
0 H l p H I @
* H1 J/v H1 ~(2s)
I c 0 10 20 30 40
Q2 [GeV2J
1 1 . 5 2 2 . 5 3 3 . 5 4 4 . 5 5 1 1 . 5 2 2 5 3 3 . 5 4 4 . 5 5
QZ(GeV2) d (Ge9)
__--- 13 / A
17 +--e- n
0 20 40 60 80 100 120 140 160 0 5 10 15 20 25 30 35 40
W(GeV) Q2(GeV2)
data from: hepex/9507001, hepex/9808020, hep-ph/9908519
theory curves: S V Goloskokov, P Kroll and B Postler, hepph/0308140
t3IW \H.\TRIk-6w kr tN WSON
AII HI and ZEUS Results
- 10 1' 8 - 3 Q
b *+ 6 W
4 -
2 -
0 H I DVCS prel.
A ZEUSDVCS 13 H I DVCS
- Freund e t 01. * NLO QCD MRSTOl -b(Q2) Donnachie-Dosch
- '7 - ' ' 9 H I DVCS -
A ZEUSDVCS t -
~ Freund e t al.
-.--. Donnachie-Dosch NLO QCD MRSTO1 -b(Q*)
r -
-
- -
- t t <W> = 82 GeV -2
10 20 30 40 50 60 70 80 90 lo 0 ' ' I ' ' I ' I ' ' ' ' ' I I I ' ' I ' ' I ' I ' I ' I ' ' ' ' ' '
Q2 [GeV2]
n 12 a c 0 H I DVCS prel. <Q2> = 8 GeV2
t -&
0 20 40 60 80 100 120 140 o ~ " ~ " t ' ~ ' ' f ~ f ~ ' ~ ' ~ '
W [GeV]
+ Good agreement between H1 results + Fair agreement between H1-prel and ZEUS results except for W N 70 GeV: HI lower by 20
IO.
Rd.5, d3
I4.\o.uk 03
-- S3A ‘QI
t. .-- cos .se
?
2r 0.4 1 HERMES Preliminary
S Stepanyan et al, CLAS Collaboration, hepex/0107043
F Ellinghaus et all HERMES Collaboration, hepex/O212019
CJ 0.6 a 0.4
- - e' p + e'y X (M,< 1.7 GeV)
- - P I 4- P2COS9
- HERMES PRELIMINARY -
- -
-0.4
- - - PI = -0.05 f 0.03 (stat)
- -I P2 = 0.11 f 0.04 (stat) -
- 1 1 I I I I 1 1 1 1 I 1 l I I I I I I I J
I 1 1 1 I I I I I
