Mass-splittings of doubly heavy baryons in QCD

TL;DR

This paper uses double ratios of sum rules to accurately calculate mass splittings of doubly heavy baryons, revealing spin and SU(3) independence and suggesting electromagnetic decay modes, with results comparable to potential models.

Contribution

First application of double ratios of sum rules to doubly heavy baryon mass splittings, providing more precise predictions and insights into their spin and SU(3) symmetry behaviors.

Findings

Mass splittings agree with potential model predictions.

Alpha_s corrections dominate the Xi*_{QQ}- Xi_{QQ} mass difference.

SU(3) mass-splittings are nearly independent of baryon spin.

Abstract

We consider (for the first time) the ratios of doubly heavy baryon masses (spin 3/2 over spin 1/2 and SU(3) mass-splittings) using double ratios of sum rules (DRSR), which are more accurate than the usual simple ratios often used in the literature for getting the hadron masses. In general, our results agree and compete in precision with potential model predictions. In our approach, the alpha_s corrections induced by the anomalous dimensions of the correlators are the main sources of the Xi^*_{QQ}- Xi_{QQ} mass-splittings, which seem to indicate a 1/M_Q behaviour and can only allow the electromagnetic decay Xi^*_{QQ} to Xi_{QQ}+ gamma but not to Xi_{QQ}+ pi. Our results also show that the SU(3) mass-splittings are (almost) independent of the spin of the baryons and behave approximately like 1/M_Q, which could be understood from the QCD expressions of the corresponding two-point correlator. Our results can improved by including radiative corrections to the SU(3) breaking terms and can be tested, in the near future, at Tevatron and LHCb.