Mondal, S and Mukherjee, S and Hegde, P (2022) Lattice QCD Equation of State for Nonvanishing Chemical Potential by Resumming Taylor Expansions. In: Physical Review Letters, 128 (2).

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Abstract
Taylor expansion in powers of baryon chemical potential (μB) is an oftused method in lattice QCD to compute QCD thermodynamics for μB>0. Based only upon the few known lowest order Taylor coefficients, it is difficult to discern the range of μB where such an expansion around μB=0 can be trusted. We introduce a resummation scheme for the Taylor expansion of the QCD equation of state in μB that is based on the npoint correlation functions of the conserved current (Dn). The method resums the contributions of the first N correlation function D1,...,DN to the Taylor expansion of the QCD partition function to all orders in μB. We show that the resummed partition function is an approximation to the reweighted partition function at μB≠0. We apply the proposed approach to highstatistics lattice QCD calculations using 2+1 flavors of Highly Improved Staggered Quarks with physical quark masses on 323×8 lattices and for temperatures T≈145176 MeV. We demonstrate that, as opposed to the Taylor expansion, the resummed version not only leads to improved convergence but also reflects the zeros of the resummed partition function and severity of the sign problem, leading to its eventual breakdown. We also provide a generalization of scheme to include resummation of powers of temperature and quark masses in addition to μB, and show that the alternative expansion scheme of [S. Borsányi, Phys. Rev. Lett. 126, 232001 (2021).PRLTAO0031900710.1103/PhysRevLett.126.232001] is a special case of this generalized resummation.
Item Type:  Journal Article 

Publication:  Physical Review Letters 
Publisher:  American Physical Society 
Additional Information:  The copyright for this article belongs to the Authors. 
Keywords:  Chemical potential; Elementary particles; Equations of state; Lattice theory; Taylor series, Baryon chemical potential; Equationofstate; Lattice QCD; Low order; Partition functions; Power; Quark mass; Resummation; Taylor coefficients; Taylor's expansion, Quantum theory, article; calculation; correlation function; flavor; partition coefficient; quark 
Department/Centre:  Division of Physical & Mathematical Sciences > Centre for High Energy Physics 
Date Deposited:  02 Jul 2022 05:04 
Last Modified:  02 Jul 2022 05:04 
URI:  https://eprints.iisc.ac.in/id/eprint/74068 
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