Test of the heavy quark-light diquark approximation for baryons with a heavy quark

TL;DR

This paper evaluates the heavy quark-light diquark approximation in baryons with a heavy quark, comparing it to full calculations and QCD predictions, revealing limitations and differences in mass estimates.

Contribution

It critically assesses the validity of the heavy quark-light diquark approximation against full calculations and QCD-based methods.

Findings

The heavy quark reduces the distance between light quarks.

Distances between heavy and light quarks are smaller than between light quarks.

Diquark approximation yields larger baryon masses than full calculations.

Abstract

We check a commonly used approximation in which a baryon with a heavy quark is described as a heavy quark-light diquark system. The heavy quark influences the diquark internal motion reducing the average distance between the two light quarks. Besides, we show how the average distance between the heavy quark and any of the light quarks, and that between the heavy quark and the center of mass of the light diquark, are smaller than the distance between the two light quarks, which seems to contradict the heavy quark-light diquark picture. This latter result is in agreement with expectations from QCD sum rules and lattice QCD calculations. Our results also show that the diquark approximations produces larger masses than the ones obtained in a full calculation.