Anja Habersetzer | Searcharxiv

arXiv2014

$τ$ Vector Spectral Function from a Chirally Invariant Hadronic Model with Weak Interaction

The linear sigma model we present here describes the vacuum phenomenology of the $N_F=2$ scalar, pseudoscalar, vector and axial-vector mesons at energies $\simeq 1\text{ GeV}$. Together with a local $SU(2)_L\times U(1)_Y$ symmetry obtained from a local transformation of the fields we obtain a gauge invariant effective description of electroweak interaction with hadrons in the vacuum. We show that the vector channel is described well and that the contributions from the direct decay of $W^- \rightarrow π^- π^0$ are, although quantitatively small, necessary to reproduce the line shape of the vector spectral function.

hep-ph↗

arXiv2013

Brief Report on the Extended Linear Sigma Model

We present a chiral effective model which exhibits all the known symmetry features of the QCD Lagrangian. The extended Linear Sigma Model (eLSM) includes (pseudo-)scalar and (axial-) vector mesons, glueballs, and baryons. It has proven to be a useful tool to understand the nature of the low-energy resonances. It can be used to describe the masses and decay widths of the known low-energy mesons and to disentangle the complicated picture of resonances in the low-energy range. We can answer some of the open questions in the low-energy region, e.g. the resonance (f_0(1500)) is a predominantly glueball state and the resonance (f_0(1370)) is most likely the chiral partner of the pion. We could also find that the resonance (N(1650)) is favoured as the chiral partner of the nucleon (N(939)). In addition the temperature dependence of the chiral condensate and the glueball condensate can be used to study the phase diagram at nonzero temperatures and densities. At nonzero density we achieve nuclear matter saturation.

hep-ph↗