Jun 13 – 17, 2011
Europe/Berlin timezone
Proceedings are now available online at <a href="http://www.slac.stanford.edu/econf/C110613/">eConf</a>

The nature of the lightest scalar meson, its Nc behavior and semi-local duality

Jun 13, 2011, 2:30 PM
Festsaal (Künstlerhaus)



talk Light Mesons Light Mesons


Dr Jose R. Pelaez (Universidad Complutense)


The leading $1/N_c$ behaviour of Unitarised Chiral Perturbation Theory distinguishes the nature of the $\rho$ and the $\sigma$. At one loop order the $\rho$ is a ${\bar q}q$ meson, while the $\sigma$ is not. However, semi-local duality between resonances and Regge behaviour cannot be satisfied for larger $N_c$, if such a distinction holds. While the $\sigma$ at $N_c=3$ is inevitably dominated by its di-pion component, Unitarised Chiral Perturbation Theory beyond one loop order reveals that as $N_c$ increases above 6-8, the $\sigma$ has a sub-dominant ${\bar q}q$ fraction up at 1.2 GeV. Remarkably this ensures semi-local duality is fulfilled for the range of $N_c \lesssim 15$, where the unitarisation procedure adopted applies.

Primary author

Dr Jose R. Pelaez (Universidad Complutense)


Dr David J. Wilson (Thomas Jefferson National Accelerator Facility) Mr Jacobo Ruiz de Elvira (Uni versidad Complutense de Madrid) Prof. Michael J. Pennington (Thomas Jefferson National Accelerator Facility)

Presentation materials