Towards a parameter-free analysis of the QCD chiral phase transition and its universal critical behavior

To quantify the universal properties of chiral phase transition in (2+1)-flavor QCD, we use an improved, renormalized order parameter for the chiral symmetry breaking. We construct ratios of this divergence-free order parameter from its values for different pairs of light quark masses. From this, we determine in a parameter-independent manner, the chiral phase transition temperature $T_c$ and the associated critical exponent $δ$ of the universality class. We present first numerical results of these calculations on $N_τ=8$ lattices, with staggered fermions.

💡 Research Summary

The paper addresses the long‑standing problem of determining the universal critical behavior of the chiral phase transition in (2+1)‑flavor QCD without relying on external model parameters. The authors start from the standard light‑quark chiral condensate (M_\ell) and its susceptibility (\chi_\ell), both of which contain ultraviolet (UV) divergent pieces that obscure their interpretation as genuine order parameters in the continuum limit. To eliminate these divergences they introduce an improved, renormalized order parameter
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