Download presentation

Presentation is loading. Please wait.

Published byChase Bishop Modified over 4 years ago

1
Deeply Virtual Compton Scattering from the Proton and the Neutron ( E00-110 & E03-106: DVCS/nDVCS ) Hall A Collaboration MeetingDecember 6, 2005 Spokespersons: Pierre-Yves Bertin, Charles Hyde-Wright, Ron Ransome, Franck Sabatie, and Eric Voutier Elena Kuchina Rutgers, The State University of New Jersey

2
Hall A DVCS at 6 GeV: Methods and Goals E00-110: Measure the absolute cross section of DVCS on proton E00-110 (3 Q² values: 1.4, 1.9, 2.3 GeV²) and on neutron E03-106 (Q²=1.9 GeV²) E03-106: Simplest access to the least known of GPDs: E First constraint of nucleon orbital angular momentum through model of E Check Handbag dominance & Test factorization of DVCS Deduce Q² dependence and relative importance of leading twist and higher twists in helicity dependent cross-section Measure linear combination of GPDs …including Re (DVCS) Unique characteristics: High luminosity (up to 4·10 37 cm -2 s -1 ) Well defined kinematics (high resolution detection of e - and γ) Method: Measure weighted cross-section differences as function of φ angle Deduce Q 2 dependence & relative importance of twist-2 and higher twists Goal:

3
DVCS experimental setup

4
contains BH propagators and some kinematics B contains twist-3 terms A is a linear combination of three GPDs evaluated at x=ξ Cross-section difference assuming handbag dominance

6
s (GeV²) Q² (GeV²) P e (Gev/c) Θ e (deg) -Θ γ* (deg) 4.942.322.3523.9114.805832 4.221.912.9519.3218.254365 3.51.53.5515.5822.293097 4.221.912.9519.3218.2524000 E00-110 p-DVCS 9-11 04 E03-106 n-DVCS 11-12 04 x Bj =0.364 Kinematics is fully defined Beam polarization was about 75.3% during the experiment (fb -1 ) 5.7572 GeV polarized 110 cm LH2 (LD2) e' (LHRS) p'(n') Experiment kinematic settings

7
Analysis Method MC includes radiative corrections (both external and internal).

8
Calorimeter acceptance Acceptance in φ is very dependent on t for large -t

9
Preliminary results on p-DVCS Difference if Yields N + -N - : 3 bins in Q 2 x 5 bins in t (x 50 bins in φ) 0.5< M x ² < 1.2 GeV 2 relatively small contribution of the twist-3 term Q 2 dependence of the twist-2 and twist-3 terms: Twist-2 term (high precision) ~ 12% variation Twist-3 term (20-30% uncertainty) is ~ 0 handbag dominance test Twist-2 absolute value & t-dependence is well reproduced by VGG model.

10
φ LD 2 target – LH 2 target Possible neutron signal ! 0.5 GeV 2 < missing mass 2 < 1.5 GeV 2 Absolute cross sections necessary to extract helicity dependence of neutron n-DVCS – Very preliminary 1.5 GeV 2 < missing mass 2 < 2.5 GeV 2 2.5 GeV 2 < missing mass 2 < 3.5 GeV 2 NO signal

11
To do Acceptance checks Virtual radiative corrections Contribution from πº Total cross-section: access to real part of DVCS and other cross-section coefficients Polarized cross sections to extract GPD E Relative asymmetry considering Proton Array and Tagger

12
Summary and Conclusions Very exciting times where first high precision data is coming out. Test of handbag dominance t-dependence and access to linear combinations of GPDs DVCS is a golden probe. New exclusive experiments in different kinematic domains and with different observables (BSA, BCA,TSA…) are needed in order to fully map out GPDs.

Similar presentations

OK

Beijing, Sept 2nd 2004 Rachele Di Salvo Beam asymmetry in meson photoproduction on deuteron targets at GRAAL MENU2004 Meson-Nucleon Physics and the Structure.

Beijing, Sept 2nd 2004 Rachele Di Salvo Beam asymmetry in meson photoproduction on deuteron targets at GRAAL MENU2004 Meson-Nucleon Physics and the Structure.

© 2018 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google