Diffractive W and Z Production at the Fermilab Tevatron

TL;DR

This paper measures the fraction of W and Z bosons produced diffractively in proton-antiproton collisions at 1.96 TeV, using the CDF-II detector, and searches for double Pomeron exchange and exclusive Z production.

Contribution

It provides the first measurement of diffractive W and Z production fractions at the Tevatron and reports on searches for rare diffractive processes with no observed signals.

Findings

Approximately 1% of W bosons are produced diffractively.

Approximately 0.9% of Z bosons are produced diffractively.

No evidence found for double Pomeron exchange or exclusive Z production.

Abstract

We report on a measurement of the fraction of events with a W or Z boson which are produced diffractively in antiproton-proton collisions at a center of mass energy of 1.96 TeV, using data from 0.6 inverse femtobarns of integrated luminosity collected with the CDF-II detector equipped with a Roman-pot spectrometer that detects the antiproton (pbar) from pbar+p --> pbar+[X+W/Z]. We find that (1.00+/- 0.11)% of Ws and (0.88+/-0.22)% of Zs are produced diffractively in a region of antiproton or proton fractional momentum loss (\xi) of 0.03<\xi<0.10 and 4-momentum transferred squared t of -1<t<0 (GeV/c)^2, where we account for the events in which the proton scatters diffractively while the antiproton dissociates, pbar+p --> [X+W/Z]+p, by doubling the measured proton dissociation fraction. We also report on searches for W and Z production in double Pomeron exchange, p+pbar --> p+[X+W/Z]+pbar, and on exclusive Z production, pbar+p --> pbar+Z+p. No signal is seen above background for these processes, and comparisons are made with expectations.