ASYMPTOTIC BEHAVIOR OF PHYSICAL AMPLITUDES IN A FINITE FIELD THEORY

1990 ◽  
Vol 05 (10) ◽  
pp. 1861-1880
Author(s):  
J.A. HELAYËL-NETO ◽  
S. RAJPOOT ◽  
A. WILLIAM SMITH

Using the N=4 super Yang-Mills theory softly broken by supersymmetric N=1 mass terms for the matter superfields, we compute the one-loop chiral+chiral→antichiral+antichiral scattering amplitude directly in superspace. By suitable choices of the mass parameters, one can endow the model with a hierarchy of light and heavy particles, and the decoupling of the heavy sector from the light-light physical amplitude is studied. We also analyze the high energy limit of the cross section for a two physical scalar scattering and find a (logs) behavior, which then respects the Froissart bound.

1990 ◽  
Vol 05 (14) ◽  
pp. 2865-2884
Author(s):  
J.A. HELAYEL-NETO ◽  
A. WILLIAM SMITH ◽  
SUBHASH RAJPOOT

Using the N=4 super-Yang-Mills theory softly broken by supersymmetric N=1 mass terms for the matter superfields, we compute the one-loop chiral+chiral→antichiral+antichiral scattering amplitude directly in superspace. By suitable choices of the mass parameters, one can endow the model with a hierarchy of light and heavy particles, and the decoupling of the heavy sector from the light-light physical amplitude is studied. We also analyze the high-energy limit of the cross-section for a two physical scalar scattering and find a (logs) behavior, which then respects the Froissart bound.


1990 ◽  
Vol 05 (24) ◽  
pp. 1983-1991 ◽  
Author(s):  
S. YU. KHLEBNIKOV ◽  
V. A. RUBAKOV ◽  
P. G. TINYAKOV

We study the total cross-section of high energy collisions in the one-instanton sector of purely bosonic theories with instantons. We find that in the limit g2 → 0, E/E sph = fixed , the leading behavior of the total cross-section is σ lot ~ exp [1/g2(−2S0 + F(E/E sph ))], where S0 is the instanton action. In the electroweak theory at E/E sph ≪ 1, the function F(E/E sph ) is determined by the gauge boson part of the instanton configuration and its explicit form is found.


1992 ◽  
Vol 07 (21) ◽  
pp. 1905-1913 ◽  
Author(s):  
M. KAWASAKI ◽  
T. MAEHARA ◽  
M. YONEZAWA

Unitarity bounds for the differential cross-section of high-energy elastic hadron-hadron scattering are obtained under the constraints of fixed total cross-section σt, elasticity x, real part to imaginary part ratio ρ of the forward scattering amplitude, and forward slope b by assuming a finite interaction range. The obtained upper bound has an observed curvature structure at small momentum transfers and is nearly saturated by the experimental data of pp and [Formula: see text] scattering at −t=0−0.3 (GeV/c)2 in the energy region [Formula: see text] , if we take the interaction radius scaled as [Formula: see text].


2014 ◽  
Vol 1 (1) ◽  
pp. 33-35
Author(s):  
Adrien Besse ◽  
Lech Szymanowski ◽  
Samuel Wallon

We investigate the longitudinal and transverse polarized cross-sections of the leptoproduction of the ρ meson in the high energy limit. Our model is based on the computation of the impact factor γ*(λγ)→ ρ (λρ) using the twist expansion in the forward limit which is expressed in the impact parameter space. This treatment involves in the final stage the twist 2 and twist 3 distribution amplitudes (DAs) of the ρ meson and the dipole scattering amplitude. Taking models that exist for the DAs and for the dipole cross-section. We get a phenomenological model for the helicity amplitudes. We compare our predictions with HERA data and get a fairly good description for large enough virtualities of the photon. PACS number(s): 13.60.Le, 12.39.St, 12.38.Bx.


An expression for the cross-section describing electron capture by protons in atomic hydrogen is derived from an expansion based on atomic wave functions. Full account is taken of momentum transfer and of the non-orthogonality of the wave functions of the initial and final states by the method due to Bates. The cross-sections have been computed for proton energies from 100 to 1 MeV. In the low energy limit, the results agree with the p.s.s. calculations of Dalgarno & Yadav and in the high energy limit with the calculations of Brinkm an & Kramers.


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