References - Bogoliubov Laboratory of Theoretical Physics - JINR

from the underlying theory. Higher-order QCD corrections for many observables sensitive
to GPDs have now also been calculated, strengthening the theoretical underpinning for
extraction of GPDs.
)
4
DVCS cross section (nb/GeV
)
4
DVCS cross section (nb/GeV
0
4
0.03
2
0
2
-0.03
4
0.02 0.022
0
0
-0.02 -0.022
0.02
0
-0.02
0.1
0.05
0
< t > = - 0.33 GeV
E00-110
Total fit
Twist - 2
2
90 180 270
φ (deg)
< t > = - 0.33 GeV
2
E00-110
Total fit
Twist - 2
E00-110
2
|BH+DVCS|
2
|BH|
2 2
|BH+DVCS| - |BH|
90 180 270
4
2
0
2
4
2
0
2
φ (deg)
< t > = - 0.28 GeV
2
90 180 270
φ (deg)
< t > = - 0.28 GeV
90 180 270
2
4
2
0
2
4
2
0
2
φ (deg)
< t > = - 0.23 GeV
2
90 180 270
φ (deg)
< t > = - 0.23 GeV
90 180 270
2
4
2
0
2
4
2
0
2
φ (deg)
< t > = - 0.17 GeV
2
90 180 270
φ (deg)
< t > = - 0.17 GeV
90 180 270
2
φ (deg)
Figure 1: Data and fit to the helicity-dependent d 4 Σ/dQ 2 dxBdtdφ, and the helicity-independent
d 4 σ/[dQ 2 dxBdtdφ] cross sections, as a function of the azimuthal angle φ between the leptonic and hadronic
planes. All bins are at 〈xB〉 =0.36. Error bars show statistical uncertainties. Solid lines show total fits
with one-σ statistical error bands. The green line is the |BH| 2 contribution to d 4 σ. The first three rows
show the helicity-dependent cross section for values of Q 2 =1.5, 1.9 and2.3 GeV 2 , respectively. The last
row shows the helicity-independent cross section for Q 2 =2.3 GeV 2 .
257
2
= 1.5 GeV
2
Q
2
= 1.9 GeV
2
Q
beam helicity-independent beam helicity-dependent