Guide to Official diffVM Files

Last updated: August 9, 1996 by BL.

diffVM is a Monte Carlo generator for diffractive processes in ep collisions based on the VDM. The main author is Benno List.

There is also an overview over banks produced by and used to steer diffVM.

This overview is not exhaustive. Files with 1993 running conditions have been left out, since they are generally not available on the dice, and also the first round of 1994 Monte Carlos is not described, because new (and, of course, better) files are now available.

Light vector meson production in DIS, 1994 e+ running

Generated: May 19, 1995 by B.L.
Version 1.05/01

1994 running conditions, 27.55GeV positrons on 820GeV protons.
Cuts on the scattered electron: E>8GeV, theta<175deg
Kinematic cuts: Q^2>4GeV^2, W>20GeV
W-dependence of the differential cross section: W^0.8 (epsilon_pom = 0.2) for the elastic case, W^0.48 (epsilon_pom = 0.12) for the proton dissociation case
Slope parameter b is constant
Q^2 dependence: standard VDM propagator, R limited to 2

Remarks:
epsilon_pom was chosen differently for the elastic and proton dissociation files to partially compensate the t_min effect. The t_min effect leads for the proton dissociation case to a steeper rise of the cross section with W than for the elastic case, because the phase space for proton dissociation grows fast with W. This is a result of the one-pomeron-exchange approximation, which is known to lead to a too fast rise of the cross section with W for proton dissocyiation (compare Tevatron results).

Known problems:
The Q^2-dependence is a bit too shallow (tail to higher Q^2 values is a bit too large), because VDM does not correctly describe the Q^2 behavior.
Recommendation: reweight events with factor ((m^2+4GeV^2)/(m^2+Q^2))^0.5, where m is the mass of the respective vector meson.

Elastic diffractive vector meson production

rho production

20000 events, cross section estimate 940pb, integrated luminosity 21.2pb^-1
b=5.5GeV^-2

Guide to Official diffVM Files

Light vector meson (rho, omega, phi) production

Excited vector meson (rho(1450), omega(1420), rho(1700), phi(1680)) production

J/psi production

psi' production

Upsilon production

Photon Dissociation

Elastic diffractive vector meson production

rho production

omega production

phi production

Vector meson production with proton dissociation

rho production

omega production

phi production

Vector meson production with proton dissociation, proton dissociation modelled by isotropic phase space decay

rho production

Elastic diffractive vector meson production

rho production

Elastic diffractive vector meson production

rho production

omega production

phi production

Vector meson production with proton dissociation

rho production

omega production

phi production

Elastic diffractive vector meson production

rho production

phi production

Diffractive vector meson production with proton dissociation

rho production

phi production

Elastic diffractive vector meson production

omega production

phi production

Elastic diffractive vector meson production

Elastic diffractive vector meson production

Elastic diffractive vector meson production

Diffractive elastic J/psi production

J/psi -> e+ e-

J/psi -> mu+ mu-

J/psi production with proton dissociation

J/psi -> e+ e-

J/psi -> mu+ mu-

Diffractive elastic J/psi production

J/psi -> e+ e-

J/psi -> mu+ mu-

J/psi production with proton dissociation

J/psi -> e+ e-

J/psi -> mu+ mu-

J/psi production with isotropic proton dissociation

J/psi -> e+ e-

J/psi -> mu+ mu-

Status:

Diffractive elastic J/psi production

J/psi -> e+ e-

J/psi -> mu+ mu-

J/psi production with proton dissociation

J/psi -> e+ e-

J/psi -> mu+ mu-

Diffractive elastic psi' production

psi' -> e+ e- X (directly or via J/psi)

psi' -> mu+ mu- X (directly or via J/psi)

psi' production with proton dissociation

psi' -> e+ e- X (directly or via J/psi)

psi' -> mu+ mu- X (directly or via J/psi)

Diffractive elastic psi' production

psi' -> mu+ mu- X (directly or via J/psi)

psi' -> e+ e- X (directly or via J/psi)

psi' production with proton dissociation

psi' -> mu+ mu- X (directly or via J/psi)

psi' -> e+ e- X (directly or via J/psi)

Diffractive elastic Upsilon production

Upsilon -> e+ e-

Upsilon -> mu+ mu-

Upsilon production with proton dissociation

Upsilon -> e+ e-

Upsilon -> mu+ mu-