Charmonium suppression in p-A collisions

TL;DR

This paper analyzes high-precision data on charmonium production in proton-nucleus collisions, challenging the standard model's assumptions about the lifetime of the octet state during formation.

Contribution

It provides a new analysis that questions the validity of the standard charmonium production model based on recent experimental data.

Findings

The octet state lifetime is much shorter than expected.

Standard production scenario assumptions are challenged.

Data suggests need for revised theoretical models.

Abstract

The new high precision data on charmonium production in proton-nucleus collisions by the E866/NuSea collaboration at Fermilab allow - together with older data at lower energies - to fix a unique set of parameters for the standard production and absorption scenario of charmonium in a proton-nucleus reaction. In this scenario the c-cbar pair is formed in an octet state, emits a gluon and continues its radial expansion in a singlet state until it has reached the charmonium radius. In all three phases it can interact with the nuclear environment. We find that the lifetime of the octet state is much shorter than acceptable on physical grounds. This challenges the physical reality of the first phase in the standard scenario.