The P{sub 33}(1232) resonance contribution into the amplitudes M{sub 1+}{sup 3/2}, E{sub 1+}{sup 3/2}, S{sub 1+}{sup 3/2} from an analysis of the p(e,e{prime}p){pi}{sup 0} data at Q{sup 2} = 2.8, 3.2, and 4 (GeV/c){sup 2} within dispersion relation approach

Journal Article · Sat Aug 01 04:00:00 EDT 1998 · Phys.Rev. D59 (1999) 054009

OSTI ID:755962

Aznauryan, I G; Stepanyan, S G

Within the fixed-t dispersion relation approach the authors have analyzed the TJNAF and DESY data on the exclusive p(e,e{prime}p){pi}{sup 0} reaction in order to find the P{sub 33}(1232) resonance contribution into the multipole amplitudes M{sup 1+}{sup 3/2}, E{sub 1+}{sup 3/2}, S{sub 1+}{sup 3/2}. As an input for the resonance and nonresonance contributions into these amplitudes the earlier obtained solutions of the integral equations which follow from dispersion relations are used. The obtained values of the ratio E2/M1 for the {gamma}{sup *}N {r_arrow} P{sub 33}(1232) transition are: 0.039{+-} 0.029, 0.121{+-} 0.032, 0.04 {+-} 0.031 for Q{sup 2}= 2.8, 3.2, and 4 (GeV/c){sup 2}, respectively. The comparison with the data at low Q{sup 2} shows that there is no evidence for the presence of the visible pQCD contribution into the transition {gamma}N {r_arrow} P{sub 33}(1232) at Q{sup 2}=3--4 GeV{sup 2}. The ratio S{sub 1+}{sup 3/2} / M{sub 1+}{sup 3/2} for the resonance parts of multipoles is: {minus}0.049 {+-} 0.029, {minus}0.099 {+-} 0.041, {minus}0.085 {+-} 0.021 for Q{sup 2}= 2.8, 3.2, and 4 (GeV/c){sup 2}, respectively. The results for the transverse form factor G{sub T}(Q{sup 2}) of the {gamma}{sup *}N {r_arrow} P{sub 33}(1232) transition are lower than the values obtained from the inclusive data. With increasing Q{sup 2}, Q{sup 4}G{sub T}(Q{sup 2}) decreases, so there is no evidence for the presence of the pQCD contribution here too.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (US)
• Sponsoring Organization: USDOE Office of Energy Research (ER) (US)
• DOE Contract Number: AC05-84ER40150
• OSTI ID: 755962
• Report Number(s): DOE/ER/40150-1512; JLAB-THY-98-31; hep-ph/9808311
• Journal Information: Phys.Rev. D59 (1999) 054009, Journal Name: Phys.Rev. D59 (1999) 054009
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
DATA ANALYSIS
DISPERSION RELATIONS
ELECTROPRODUCTION
FORM FACTORS
MULTIPOLE TRANSITIONS
PERTURBATION THEORY
PIONS NEUTRAL
QUANTUM CHROMODYNAMICS
RESONANCE PARTICLES