Free Meson Seminars

A New Way to Resum the Finite-Density Lattice QCD Taylor Series.

by Prof. Prasad Hegde (IISc., Bengaluru)

Thursday, November 3, 2022 from to (Asia/Kolkata)
at AG 69 and Zoom
Description Please contact rishi(at)theory(dot)tifr(dot)res(dot)in for the zoom meeting id and the password for this seminar.

Taylor expansion of the QCD equation of state in the baryon chemical potential $\mu_B$ has proven successful in circumventing the sign problem of lattice QCD. However, resumming the Taylor series is necessary both due to the slow convergence of the series as well as the difficulty in calculating the higher-order coefficients. A well-known way of resumming a Taylor series is the method of Pade approximants. Recently another way to resum the series, namely exponential resummation, was proposed and applied to calculate the QCD Equation of State. Despite its advantages, one drawback of exponential resummation is the presence of stochastic bias. I will describe two ways of removing this bias, namely cumulant expansion, and the more recently proposed unbiased exponential resummation. Especially the latter method is able to retain the advantages of exponential resummation while also eliminating bias up to a certain order. I will describe the method and present our recent results for the excess pressure, baryon density and the average phase factor which is a measure of the severity of the sign problem.