Speaker
Santiago Cortes
(Universidad de los Andes)
Description
We study how the thermal properties of the f0(500) pole behave in a regime
where temperature is below its critical chiral transition value. We attain this
by considering an O(N +1)/O(N) invariant Non-Linear Sigma Model (NLSM)
for a large number of N massless pions as an approach for the dynamics of
Low Energy QCD, and after introducing a thermal bath via the imaginary
time formalism. At T = 0, we fit the parameters of the NLSM such that we
can describe both older and newer scattering data in the scalar channel and
generate dynamically its associated resonance, thus obtaining a pole position
that agrees with experimental determinations. Next, we calculate the pion
scattering amplitude at finite T and check that exact thermal unitarity holds.
Also, we show that one can define a proper renormalization scheme with T = 0
counterterms such that the renormalized T-dependent amplitude can be chosen
to depend only on a few parameters. Next, we analyze the behaviour of the
f0(500) pole at finite T, which is consistent with chiral symmetry restoration
when the scalar susceptibility is saturated by the f0(500) state, in a second-
order transition scenario and in accordance with lattice and theoretical analysis.
Furthermore, we find its associated critical exponent and check that it lies within
the range expected for a O(N) universality class.
Author
Santiago Cortes
(Universidad de los Andes)
Co-authors
Dr
John Morales
(Universidad Nacional de Colombia, sede Bogotá)
Dr
Ángel Gómez-Nicola
(Universidad Complutense de Madrid)
