I w ill report results on the time evolution of correl ation functions after quantum quenches in the sine -Gordon model computed using a semiclassical appro ach which is expected to yield accurate results fo r small and slow quenches producing slow quasipart icles with low density. I will demonstrate this by showing that the method reproduces the results of a recent form factor calculation of the relaxatio n of expectation values. Extending these results\, the expectation values of most vertex operators w ill be shown not to decay to zero. I will give ana lytic expressions for the relaxation of dynamic co rrelation functions to find that they have diffusi ve behavior for large timelike separation. At the end of my talk I will show preliminary results obt ained with an improved "semi-semiclassical" versio n of the method. LOCATION:Seminar Room 1\, Newton Institute CONTACT:info@newton.ac.uk END:VEVENT END:VCALENDAR