Predictions of masses for light hybrid baryons

TL;DR

This paper predicts the masses of light hybrid baryons using QCD sum rules, identifying stable states and proposing experimental search methods to understand gluonic effects in QCD.

Contribution

The study constructs local $qqqg$ interpolating currents and establishes stable QCD sum rules for certain hybrid baryon channels, providing mass predictions and experimental search strategies.

Findings

Lowest-lying hybrid baryon predicted at ~2.01 GeV

Stable sum rules established for specific parity channels

Proposed detection via $ ext{Upsilon}/ ext{psi}$ decays

Abstract

Within the method of parity-projected QCD sum rules, we study the mass spectra of light hybrid baryons with $I(J^{P})=1/2(1/2^{\pm}), 3/2(1/2^{\pm}), 1/2(3/2^{\pm}), 3/2(3/2^{\pm})$ by constructing the local $qqqg$ interpolating currents. We calculate the correlation functions up to dimension eight condensates at the leading order of $\alpha_{s}$. The stable QCD Lapalce sum rules can be established for the positive-parity $N_{1/2^+}, \Delta_{3/2^+}, \Delta_{1/2^+}$ and negative-parity $N_{1/2^-}, N_{3/2^-}, \Delta_{1/2^-}$ channels to extract their mass spectra. The lowest-lying hybrid baryons are predicted to be the positive-parity $N_{1/2^+}$ state around 2.01 GeV. These hybrid baryons mainly decay into conventional baryon plus meson final states. We propose to search for the light hybrid baryons through the $\Upsilon/\psi(3686)$ decays via the three-gluon emission mechanism in BESIII and BelleII experiments. Hopefully our studies of the light hybrid baryons will be useful for understanding the excited baryon spectrum and the behavior of gluonic degrees of freedom in QCD.