Obtaining σ → γγ Width from Nucleon Polarizabilities
نویسندگان
چکیده
We propose a new method that fixes the coupling to two photons of the recently found lightest QCD resonance, the σ. This coupling provides crucial information for discriminating the yet unknown nature of this special state. Our method uses available data on the nucleon polarizabilities together with analyticity and unitarity. Taking into account all the uncertainties, our result is Γpole = 1.2± 0.4 keV. September 2008 Work supported in part by MICINN, Spain and FEDER, European Commission (EC) Grant Nos. FPA2005-01678 (J.B.), FPA2006-05294 (J.P.), Consolider-Ingenio 2010 Grant No. CSD2007-00042 – CPAN, by Junta de Andalućıa Grants No. P05-FQM 101 (J.P.), P05-FQM 467 (J.P.) and P07-FQM 03048 (J.P.) and by the EC RTN network FLAVIAnet Contract No. MRTN-CT-2006-035482 (J.P.). Invited talk given by J.P. at “14 International Conference on Quantum Chromodynamics (QCD ’08)”, 7-12 July 2008, Montpellier, France.
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