High Energy / Nuclear Theory / RIKEN Seminars
# [Hybrid RBRC seminar] Quark and gluon entanglement in the light-front wave function of the proton at moderate x

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US/Eastern

2-160
### 2-160

Description

the proton has recently received much attention. In this talk we shall

focus instead on the regime of moderate x where the proton may be

dominated by an effective, non-perturbative 3-quark Fock state, plus

corrections from the |qqqg> Fock state.

We point out that color degrees of freedom in the |qqq> state are

maximally entangled. On the other hand, for N_c --> infinity the

spatial wave function of the proton factorizes into valence quark wave

functions determined by a mean field (E. Witten, Nucl. Phys. B 160

(1979) p. 57), and there is no entanglement of spatial degrees of

freedom. A model calculation at Nc=3, using a well known valence quark

light-front wave function by Brodsky and Schlumpf, predicts percent

level entanglement of spatial degrees of freedom.

Using light-cone perturbation theory we also obtain the qqqg wave function

and the associated density matrix. Tracing out the quarks, we derive

the reduced density matrix for the degrees of freedom of the gluon.

This density matrix again predicts maximal entanglement of gluon color

but also indicates stronger entanglement of (some of) the gluon

spatial degrees of freedom than for quarks in the |qqq> state.

Organized by

Vladi Skokov