Speaker
Paolo Di Vecchia
(Nordita)
Description
We extend the effective Lagrangian for pseudo-scalar mesons
that includes the effect of the axial anomaly, gives a
satisfactory spectrum of pseudo-scalar mesons and allows one
to compute the $\theta$ dependence of hadronic processes,
to include the axion. We use it to show that the $\theta$
dependence disappears and we compute various properties of
the axion. In particular, we show that the mass of the axion
is given, in the chiral limit, by the Weinberg-Wilczek
formula in terms of the quark masses with the addition of a
term containing the topological susceptibility of Yang-Mills
theory. This additional factor is irrelevant at zero
temperature but could become important at finite temperature.
Primary author
Paolo Di Vecchia
(Nordita)