Evidence for the bottom baryon resonance state Lambda_b* with the CDF II detector

TL;DR

This paper reports evidence for an excited bottom baryon resonance, Lambda_b*, observed in proton-antiproton collision data with a significance of 4.6 sigma, measuring its mass at approximately 5920 MeV.

Contribution

First evidence for the Lambda_b* resonance state in proton-antiproton collisions using the CDF II detector with a detailed decay analysis.

Findings

Observed Lambda_b* mass: 5919.5 MeV

Significance of the signal: 4.6 sigma

Data sample: 9.6/fb from Fermilab Tevatron

Abstract

Using data from proton-antiproton collisions at Ecms=1.96 TeV recorded by the CDF II detector at the Fermilab Tevatron, we present evidence for the excited resonance state Lambda_b* in its fully reconstructed decay mode to Lambda_b0 pi+ pi- where Lambda_b0 -->Lambda_c+ (-->proton K- pi+) pi-. The analysis is based on a data sample corresponding to an integrated luminosity of 9.6/fb collected by an online event selection based on tracks displaced from the proton-antiproton interaction point. The local significance of the observed signal is 4.6 Gaussian sigmas. while the significance of the signal for the search region is 3.5 Gaussian sigmas. The mass of the observed state is found to be 5919.5+-0.35+-1.72 MeV .