QCD Chemistry: Remarks on Diquarks

TL;DR

This paper critically examines the existence of $Qq$ diquarks, arguing they likely do not exist, and proposes studying pre-asymptotic corrections in heavy baryon decays as a way to confirm this.

Contribution

The paper provides a theoretical review of diquark concepts and suggests a novel approach to test their existence through decay analysis of heavy baryons.

Findings

Arguments against the existence of $Qq$ diquarks with sufficiently heavy $Q$

Proposes studying pre-asymptotic corrections in $Qqq$ baryon decays

Highlights differences in $cq$ attraction effects between charm and bottom baryons

Abstract

In connection with recent discoveries of heavy-quark containing exotic states publications discussing $Qq$ diquarks ($Q,q$ stand for a heavy and light quarks, respectively) proliferated in the literature. After a brief summary of the diquark concept I review various general reasons why the $Qq$ diquark (with sufficinetly heavy $Q$) does not exist. Then I argue (this is the focus of my talk) that the most direct way to confirm non-existence of the $Qq$ diquarks is the study of pre-asymptotic corrections in the inclusive decays of $Qqq$ baryons, e.g. $\Lambda_b$. Since the $c$ quarks are much lighter than $b$, namely, $m_b^2/m_c^2\sim 11$, traces of the $cq$ attraction in the color anti-triplet spin-0 state may or may not be present in the $cqq$ baryons.