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1. New 4D lattice QCD equation of state: Extended density coverage from a generalized $T^{\prime }$ expansion

   https://doi.org/10.1103/2dmh-26yh  

   Abuali, Ahmed; Borsányi, Szabolcs; Fodor, Zoltán; Jahan, Johannes; Kahangirwe, Micheal; Parotto, Paolo; Pásztor, Attila; Ratti, Claudia; Shah, Hitansh; Trabulsi, Seth A (September 2025, Physical Review D)

   We present a new equation of state for QCD in which the temperature $T$and the three chemical potentials for baryon number ${\mu }_B$, electric charge ${\mu }_Q$, and strangeness ${\mu }_S$can be varied independently. This result is based on a generalization of the $T^{\prime }$expansion scheme, thanks to which the diagonal ${\mu }_B$extrapolation was pushed up to a baryo-chemical potential ${\mu }_B/T\sim 3.5$for the first time. This considerably extended the coverage of the Taylor expansion, limited to ${\mu }_B/T<2.5–3$. As a consequence, we are able to offer a substantially larger coverage of the four-dimensional QCD phase diagram as well, compared to previously available Taylor expansion results. Our findings are based on new continuum estimated lattice data on the full set of second- and fourth-order fluctuations. 

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2. 4D-TExS: A new 4D lattice-QCD equation of state with extended density coverage

   https://doi.org/10.1051/epjconf/202531606002  

   Jahan, Johannes; Abuali, Ahmed; Borsányi, Szabolcs; Kahangirwe, Micheal; Parotto, Paolo; Pásztor, Attila; Ratti, Claudia; Shah, Hitansh; Trabulsi, Seth A (January 2025, EPJ Web of Conferences)

   Cheshkov, C; Guernane, R; Maire, A (Ed.)

   Although calculations of QCD thermodynamics from first-principle lattice simulations are limited to zero net-density due to the fermion sign problem, several methods have been developed to extend the equation of state (EoS) to finite values of theB,Q,Schemical potentials. Taylor expansion aroundµ_i=0 (i = B,Q,S) enables to cover with confidence the region up toµ_i/T< 2.5. Recently, a new method has been developed to compute a 2D EoS in the (T,µ_B) plane. It was constructed through aT-expansion scheme (TExS), based on a resummation of the Taylor expansion, and is trusted up to densities aroundµ_B/T= 3.5. We present here the new 4D-TExS EoS, a generalization of the TExS to all 3 chemical potentials, expected to offer a larger coverage than the 4D Taylor expansion EoS. After explaining the basics of theT-Expansion Scheme and how it is generalized to multiple dimensions, we will present results for thermodynamic observables as functions of temperature and both finite baryon and strangeness chemical potentials. 

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3. QCD critical point, Lee-Yang edge singularities, and Padé resummations

   https://doi.org/10.1103/PhysRevC.110.015203  

   Başar, Gökçe (July 2024, Physical Review C)

   I analyze the trajectory of the Lee-Yang edge singularities of the QCD equation of state in the complex baryon chemical potential ( ${\mu }_B$) plane for different values of the temperature by using the recent lattice results for the Taylor expansion coefficients up to eighth order in ${\mu }_B$and various resummation techniques that blend in Padé expansions and conformal maps. By extrapolating from this information, I estimate for the location of the QCD critical point: $T_c\approx 100$MeV, ${\mu }_c\approx 580$MeV. I also estimate the crossover slope at the critical point to be ${\alpha }_1\approx 9^{\circ }$and further constrain the nonuniversal mapping parameters between the three-dimensional Ising model and QCD equations of state. Published by the American Physical Society2024 

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4. Lattice QCD equation of state at finite chemical potential from an alternative resummation: Strangeness neutrality and beyond

   https://doi.org/10.1051/epjconf/202327601014  

   Parotto, Paolo; Borsányi, Szabolcs; Fodor, Zoltan; Guenther, Jana N.; Kara, Ruben; Pásztor, Attila; Ratti, Claudia; Szabó, Kalman K. (January 2023, EPJ Web of Conferences)

   Kim, Y.; Moon, D.H. (Ed.)

   In this contribution we present a resummation of the Quantum Chromodynamics (QCD) equation of state from lattice simulations at imaginary chemical potentials. We generalize the scheme introduced in a previous work [1], to the case of non-zero strangeness chemical potential. We present continuum extrapolated results for thermodynamic observables in the temperature range 130MeV ≤ T ≤ 280 MeV, for chemical potentials up to μ B / T = 3:5, along the strangeness neutral line. Furthermore, we relax the constraint of strangeness neutrality, by extrapolating to small values of the strangeness-to-baryon-number ratio R = n S / n B . 

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5. Lattice-based equation of state with 3D ising critical point

   https://doi.org/10.1051/epjconf/202429614013  

   Kahangirwe, Micheal; Bass, Steffen A; Jahan, Johannes; Moreau, Pierre; Parotto, Paolo; Ratti, Claudia; Soloveva, Olga; Stephanov, Misha; Bratkovskaya, Elena (January 2024, EPJ Web of Conferences)

   Bellwied, R; Geurts, F; Rapp, R; Ratti, C; Timmins, A; Vitev, I (Ed.)

   The BEST Collaboration equation of state combining lattice data with the 3D Ising critical point encounters limitations due to the truncated Taylor expansion up toμ_B/T~ 2.5. This truncation consequently restricts its applicability at high densities. Through a resummation scheme, the lattice results have been extended toμ_B/T= 3.5. In this article, we amalgamate these ideas with the 3D-Ising model, yielding a family of equations of state valid up toμ_B= 700MeV with the correct critical behavior. Our equations of state feature tunable parameters, providing a stable and causal framework-a crucial tool for hydrodynamics simulations. 

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