Analysis of the 1S and 2S states of Lambda(Q) and Xi(Q) with QCD sum rules

In this article, we study the ground states and the first radial excited states of the flavor antitriplet heavy baryon states Lambda(Q) and Xi(Q) with the spin-parity J(P) = 1/2(+) by carrying out operator product expansion up to vacuum condensates of dimension in a consistent way. We observe for the first time that the higher dimensional vacuum condensates play an important role, and obtain very stable QCD sum rules with variations of the Borel parameters for the heavy baryon states. The predicted masses, 6.08 +/- 0.09 GeV, 2.78 +/- 0.08 GeV, and 2.96 +/- 0.09 GeV for the first radial excited states, Lambda(b)(2S), Lambda(c)(2S), and Xi(c)(2S), and, respectively, are in excellent agreement with the experimental data and support assigning Lambda(b)(6072), Lambda(c)(2765), and Xi(c)(2980/2970) to be the first radial excited states of Lambda(b), Lambda(c), and Xi(c), respectively. The predicted mass 6.24 +/- 0.07 GeV for Xi(b)(2S) can be confirmed using experimental data in the future.

Automated summary

In this research, stable QCD sum rules were obtained by carrying out operator product expansion up to vacuum condensates of different dimensions, leading to successful prediction of masses for several heavy baryon states. The results are in good agreement with experimental data, supporting the assignment of certain states as the first radial excited states in the heavy baryon spectrum.