Exceptional Seminar Jacob Sonnenschein (Tel Aviv University)
I will start with briefly describing the HISH ( Holography In- spired Hadronic String) model and reviewing the fits of the spectra of mesons, baryons, glueballs and exotic hadrons. I will present the determination of the hadron strong decay widths. The main decay mechanism is that of a string splitting into two strings. The corresponding total decay width behaves as Γ = πATL/2 where T and L are the tension and length of the string and A is a dimensionless universal constant. The partial width of a given decay mode is given by Γ_i/Γ = Φ_i exp(−2πCm^2_sep/T) where Φi is a phase space factor, msep is the mass of the ”quark” and ”antiquark” created at the splitting point, and C is a dimensionless coefficient close to unity. I will show the fits of the theoretical results to experimental data for mesons and baryons. I will examine both the linearity in L and the expo- nential suppression factor. The linearity was found to agree with the data well for mesons but less for baryons. The extracted coefficient for mesons A = 0.095 ± 0.015 is indeed quite universal. The exponential suppression was applied to both strong and radiative decays. I will discuss the relation with string fragmentation and jet formation. I will extract the quark-diquark structure of baryons from their decays. A stringy mechanism for Zweig sup- pressed decays of quarkonia will be proposed and will be shown to reproduce the decay width of Υ states. The dependence of the width on spin and flavor symmetry will be discussed. We further apply this model to the decays of glueballs and exotic hadrons.