Bottomonium spectrum at finite temperature

Abstract

We investigate the modification of S and P wave states in the bottomonium spectrum above and below the deconfinement crossover temperature through their spectral functions obtained from the maximum entropy method. Anisotropic ensembles with $N_f=2+1$ Wilson clover fermions with tadpole-improvement are used while the bottom quark is treated with an improved non-relativistic action. We observe significant modifications of the P wave ${\chi }_{b1}$ ground state directly above the crossover temperature, $T_c$, while the S wave ${\rm Y}$ ground state remains relatively unchanged up to temperatures of almost $2T_c$. This evidence supports earlier conclusions from our FASTSUM collaboration of the immediate dissociation of the P wave states above $T_c$ and the survival of the S wave ground states up to $2T_c$.

Comments: presented at the 31st International Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013, Mainz, Germany