251 research outputs found
BHAGEN-1PH: A Monte Carlo event generator for radiative Bhabha scattering
BHAGEN-1PH is a FORTRAN program providing fast Monte Carlo event generation
of the process , within electroweak theory, for
both unpolarized beams and also for the longitudinally polarized electron beam.
The program is designed for final leptons outside a small cone around the
initial leptons direction and has a new algorithm allowing also for a fast
generation of non collinear initial and final emission, as well as for
asymmetric and different angular cuts for final leptons.Comment: 23 pages, plain Tex, no figure
Numerical evaluation of the general massive 2-loop sunrise self-mass master integrals from differential equations
The system of 4 differential equations in the external invariant satisfied by
the 4 master integrals of the general massive 2-loop sunrise self-mass diagram
is solved by the Runge-Kutta method in the complex plane. The method, whose
features are discussed in details, offers a reliable and robust approach to the
direct and precise numerical evaluation of Feynman graph integrals.Comment: 1+21 pages, Latex, 5 ps-figure
The Threshold Expansion of the 2-loop Sunrise Selfmass Master Amplitudes
The threshold behavior of the master amplitudes for two loop sunrise
self-mass graph is studied by solving the system of differential equations,
which they satisfy. The expansion at the threshold of the master amplitudes is
obtained analytically for arbitrary masses.Comment: 1+18 pages, Latex, no figures, as in Journal reference with more
changes in Eq.(31),(42),(45
Numerical evaluation of the general massive 2-loop 4-denominator self-mass master integral from differential equations
The differential equation in the external invariant p^2 satisfied by the
master integral of the general massive 2-loop 4-denominator self-mass diagram
is exploited and the expansion of the master integral at p^2=0 is obtained
analytically. The system composed by this differential equation with those of
the master integrals related to the general massive 2-loop sunrise diagram is
numerically solved by the Runge-Kutta method in the complex p^2 plane. A
numerical method to obtain results for values of p^2 at and close to thresholds
and pseudo-thresholds is discussed in details.Comment: Latex, 20 pages, 7 figure
Simulation of the process within electroweak theory with longitudinally polarized initial electrons
We present simple analytic expressions for the distributions of the Bhabha
scattering process with emission of one hard photon, including weak boson
exchanges, and with longitudinal polarization of the initial electron. The
results from the Monte Carlo generator BHAGEN-1PH, based on these expressions,
are presented and compared, for the unpolarized case, with those existing in
literature.Comment: 9 pages, plain Tex, no figures, small change in Table
The Pseudothreshold Expansion of the 2-loop Sunrise Selfmass Master Amplitudes
The values at pseudothreshold of two loop sunrise master amplitudes with
arbitrary masses are obtained by solving a system of differential equations.
The expansion at pseudothreshold of the amplitudes is constructed and some
lowest terms are explicitly presented.Comment: 1+22 pages, Latex, no figures, changes in Eq.(41),(44),(47
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