Title: How the topology of the QCD vacuum influences the proton's spin

Speaker: Prof. Raju Venugopalan, Brookhaven National Lab, USA

Abstract: A remarkable feature of the standard model of physics is that the topology of the vacuum can influence dynamical processes. A striking example is the decay of a pion into two photons, for which the decay rate without topology would differ by a factor of a 1000 from the correct result (which agrees with experiment to percent accuracy) that includes the effects of topology. We argue similarly that how the many-body dynamics of spinning quarks and gluons influences the spin of the proton is strongly influenced by the topological susceptibility of the QCD vacuum. In particular, we show that novel "sphaleron" topological transitions can rapidly quench the proton's spin at high energies. This effect can be measured for the first time at an Electron-Ion Collider.