Paper
Observation and studies of double J/psi production at the Tevatron
Authors
D0 Collaboration
Abstract
We present the observation of doubly-produced mesons with the D0 detector at Fermilab in collisions at TeV. The production cross section for both singly and doubly-produced mesons is measured using a sample with an integrated luminosity of 8.1fb. For the first time, the double production cross section is separated into contributions due to single and double parton scatterings.
Using these measurements, we determine the effective cross section , a parameter characterizing an effective spatial area of the parton-parton interactions and related to the parton spatial density inside the nucleon.