Observation and studies of double J/psi production at the Tevatron

Abstract

We present the observation of doubly produced J/psi mesons with the D0 detector at Fermilab in p (p) over bar collisions at root s = 1.96 TeV. The production cross section for both singly and doubly produced J/psi mesons is measured using a sample with an integrated luminosity of 8.1 fb(-1).

For the first time, the double J/psi production cross section is separated into contributions due to single and double parton scatterings. Using these measurements, we determine the effective cross section seff, a parameter characterizing an effective spatial area of the parton-parton interactions and related to the parton spatial density inside the nucleon.

Keywords

• psi-psi-production
• double-parton scattering
• root s=1.8 tev
• pp collisions
• p(p)over-bar collisions
• run-ii
• detector
• physics