Searcharxiv⌕ Search

arXiv subjects

M. Caffo

Publications and source records attributed to M. Caffo.

13 recordsLinked to original sources
arXiv2003

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.

hep-ph↗
arXiv2002

Numerical evaluation of master integrals from differential equations

The 4-th order Runge-Kutta method in the complex plane is proposed for numerically advancing the solutions of a system of first order differential equations in one external invariant satisfied by the master integrals related to a Feynman graph. The particular case of the general massive 2-loop sunrise self-mass diagram is analyzed. The method offers a reliable and robust approach to the direct and precise numerical evaluation of master integrals.

hep-ph↗
arXiv2002

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.

hep-ph↗
arXiv1998

Master Equations for Master Amplitudes

The general lines of the derivation and the main properties of the master equations for the master amplitudes associated to a given Feynman graph are recalled. Some results for the 2-loop self-mass graph with 4 propagators are then presented.

hep-th↗
arXiv1998

The Master Differential Equations for the 2-loop Sunrise Selfmass Amplitudes

The master differential equations in the external square momentum p^2 for the master integrals of the two-loop sunrise graph, in n-continuous dimensions and for arbitrary values of the internal masses, are derived. The equations are then used for working out the values at p^2 = 0 and the expansions in p^2 at p^2 =0, in (n-4) at n to 4 limit and in 1/p^2 for large values of p^2 .

hep-th↗
arXiv1997

BHAGEN95: a Monte Carlo program for Bhabha scattering at LEP1/SLC and LEP2 energies

We present the Monte Carlo program BHAGEN95, for calculating the cross-section of the Bhabha scattering process at LEP1/SLC and LEP2 energies, usable with continuity from small to large-angle configurations. We discuss some improvements in the event generator BHAGEN94, which is now part of the new code. In particular the weak and QCD corrections are implemented up to two loops for the relevant contributions, and the emission of one hard photon is treated exactly. We have included all the radiative corrections which are necessary to obtain, for a typical experimental event selection, a precision of 0.1-0.2% at small-angle. At large-angle we estimate a precision of 0.5%, with the exception of the region where the beam energy is a few GeV above the Z boson resonance, where it is up to 1%. A detailed comparison with other codes for both small-angle and large-angle Bhabha scattering is performed.

hep-ph↗
arXiv1996

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 $e^+ e^- \to e^+ e^- γ$, 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.

hep-ph↗
arXiv1996

Simulation of the process $e^+ e^- \mapsto e^+ e^- γ$ 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.

hep-ph↗
arXiv1996

Event Generators for Bhabha Scattering

The results obtained by the "Event Generators for Bhabha Scattering" working group during the CERN Workshop "Physics at LEP2" (1994/1995) are presented.

hep-ph↗