Proton--neutron mass difference, electroproduction, and photoabsorption in an analytic model of the virtual Compton amplitude

Journal Article · Sat Nov 01 04:00:00 EST 1975 · Phys. Rev., D, v. 12, no. 9, pp. 2709-2724

DOI:https://doi.org/10.1103/PhysRevD.12.2709· OSTI ID:4070655

Deo, B B; Mahapatra, B P

An analytic model of the forward (virtual) Compton amplitude is proposed which satisfies $nu$ plane analyticity, s--u crossing symmetry, Regge behavior, and Bjorken scale invariance in appropriate limits. The model is constructed using the method of conformal mapping. Very good fits are obtained to the electroproduction data on $nu$$W$$sub 2$/sup p/, 2mW$sub 1$/sup p/, $nu$$W$$sub 2$/ sup p/ - $nu$$W$$sub 2$/sup n/, $nu$$W$$sub 2$/sup n//$nu$$W$$sub 2$/sup p/, $nu$R/sub p/, and 1 + $nu$$W$$sub 2$/sup n//$nu$$W$$sub 2$/sup p/ and to the photoabsorption data on sigma/sub T/($gamma$p), sigma/sub T/$gamma$n), and sigma/sub T/($gamma$p) - sigma/sub T/($gamma$n). The scale-invariance breaking at finite Q$sup 2$ as exhibited by the data on $nu$W/subp/$sub 2$ plotted as a function of Q$sup 2$ with $omega$ fixed is also successfully reproduced. The p--n mass difference calculated using the Cottingham formula is finite. In particular, it is shown that a set of parameters exists for which the general condition for no logarithimic divergence even in the presence of Bjorken scaling giving by lim/sub Q$sup 2$ $Yields$ infinity/Q$sup 4$$delta$$t$$sub 1$/sup I/(-Q$sup 2$,0) = ($alpha$m/$pi$) integral$sub 0$$sup 1$ dx [$delta$$F$$sub 2$(x) + 2x$delta$$F$$sub 1$(x)] can be realized consistent with theoretical considerations and experimental data. The final result of our calculation of the mass difference is (-1.96 +- 0.52) MeV, which is to be compared with the experimental value of - 1.293 MeV. (AIP)

• Research Organization: Department of Physics, Utkal University, Bhubaneswar-751004, Orissa, India
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-021394
• OSTI ID: 4070655
• Journal Information: Phys. Rev., D, v. 12, no. 9, pp. 2709-2724, Journal Name: Phys. Rev., D, v. 12, no. 9, pp. 2709-2724; ISSN PRVDA
• Country of Publication: United States
• Language: English

Related Subjects

*COMPTON EFFECT-- SCATTERING AMPLITUDES
*ELECTROPRODUCTION-- STRUCTURE FUNCTIONS
*NUCLEONS-- MASS DIFFERENCE
641102*
ANALYTIC FUNCTIONS
CONFORMAL MAPPING
CROSSING SYMMETRY
N64220* --Physics (High Energy)--Particle Interactions & Properties (Theoretical)--Electromagnetic
N64260 --Physics (High Energy)--Particle Interactions & Properties (Theoretical)--Strong (Baryon No. = 1)
REGGE POLES
S CHANNEL
SCALE INVARIANCE
U CHANNEL