Light scalar mesons in QCD
Abstract
Description
I present a mini-review of the masses and couplings of the bare (unmixed) light scalar mesons : $\bar qq, (\overline{qq})(qq), (\bar qq)(\bar qq), gg$ from QCD spectral sum rules (QSSR) and low-energy theorems (LET) which we compare with recent lattice calculations when available. Some unbiased comments on the different scenarios are given. The possiblity for the $σ(0.6)$ to be mostly a gluonium/glueball with a huge violation of the OZI rule in its decay is discussed. This review complements and updates the ones presented earlier [1]. Despite some progresses, the internal structure of the light scalar mesons remain puzzling, and some further efforts are required. It will be more fun at LHC if the Higgs of the Standard Model is a $σ$-like resonance.
6 pages, Talk given at QCD 08 (7-12th july, Montpellier) and Scientific part of the invited talk for a tribute to Paco Yndurain at Confinement8 (3-7th september, Mainz)
6 pages, Talk given at QCD 08 (7-12th july, Montpellier) and Scientific part of the invited talk for a tribute to Paco Yndurain at Confinement8 (3-7th september, Mainz)