Total Cross Sections

The SigmaTotal class returns the total, elastic, diffractive and nondiffractive cross sections in hadronic collisions, and also the slopes of the d(sigma)/dt distributions. The parametrizations used are from [Sch97] which borrows some of the total cross sections from [Don92].

The allowed combinations of incoming particles are p + p, pbar + p, pi+ + p, pi- + p, pi0/rho0 + p, phi + p, J/psi + p, rho + rho, rho + phi, rho + J/psi, phi + phi, phi + J/psi, J/psi + J/psi. The strong emphasis on vector mesons is related to the description of gamma + p and gamma + gamma interactions in a Vector Dominance Model framework (which will not be available for some time to come, so this is a bit of overkill).

Variables

If the internally implemented cross section parametrizations are not satisfactory, it is possible to override the cross section values (but currently not the t slopes), with

flag  SigmaTotal:setOwn   (default = no)
Allow a user to set own cross sections by hand; yes/no = true/false.

When SigmaTotal:setOwn = yes, the user is expected to set values for the corresponding cross sections:

parm  SigmaTotal:sigmaTot   (default = 80.; minimum = 0.)
Total cross section in mb.

parm  SigmaTotal:sigmaEl   (default = 20.; minimum = 0.)
Elastic cross section in mb.

parm  SigmaTotal:sigmaXB   (default = 8.; minimum = 0.)
Single Diffractive cross section A + B -> X + B in mb.

parm  SigmaTotal:sigmaAX   (default = 8.; minimum = 0.)
Single Diffractive cross section A + B -> A + X in mb.

parm  SigmaTotal:sigmaXX   (default = 4.; minimum = 0.)
Double Diffractive cross section A + B -> X_1 + X_2 in mb.

Note that the total cross section subtracted by the elastic and various diffractive ones gives the inelastic nondiffractive cross section, which therefore is not set separately. If this cross section evaluates to be negative the internal parametrizations are used instead of the ones here. However, since the nondiffractive inelastic cross section is what makes up the minimum-bias event class, and plays a major role in the description of multiple interactions, it is important that a consistent set is used.