Abstract
We confront the thermal NLO vector spectral function (both the transverse and longitudinal channel with respect to spatial momentum, both above and below the light cone) with continuum-extrapolated lattice data (both quenched and with Nf = 2, at T ∼ 1.2Tc). The perturbative side incorporates new results, whose main features are summarized. The resolution of the lattice data is good enough to constrain the scale choice of αs on the perturbative side. The comparison supports the previous indication that the true spectral function falls below the resummed NLO one in a substantial frequency domain. Our results may help to scrutinize direct spectral reconstruction attempts from lattice QCD.
Highlights
Vanishing momentum (k = 0) initially suggested that perturbation theory works well [7,8,9]
After implementing proper resummation close to light cone, these expressions can be inserted on the right-hand side of eq (1.3), and subsequently the left-hand side can be compared with lattice data
Motivated by a comparison with lattice data, unresummed NLO (2-loop) vector spectral functions have recently been extended into two new domains [38]: below the light cone (ω < k), and to a longitudinal polarization that vanishes at the light cone but is non-zero elsewhere
Summary
Kn is a bosonic Matsubara frequency, viz. We denote K2 ≡ kn2 + k2, with k ≡ |k|. We are mostly interested in a spectral function, which can be obtained as an imaginary part of the Euclidean correlator, ρμν (K) = Im Πμν (K) kn→−i[ω+i0+]. [35], we are interested in the linear combinations (2.2). Denoting by g2 = 4παs the gauge coupling, by Nc the number of colours, by CF ≡ (Nc2−1)/(2Nc) the quadratic Casimir coefficient, and by Σ{P} a sum-integral with fermionic. The NLO expressions for ΠV ≡ Πμμ and Π00 can be cast in the forms. The spectral functions corresponding to all structures here are worked out in ref. The spectral functions corresponding to all structures here are worked out in ref. [38]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
