Azimuthally-sensitive interferometry and the source lifetime at RHIC

Pion interferometry (“HBT”) measurements relative to the reaction plane provide an estimate of the transverse source anisotropy at freeze-out, which probes the system dynamics and evolution duration. Measurements by the STAR Collaboration indicate that the source is extended increasingly out-of-plane with increasing impact parameter, suggesting a short evolution duration roughly consistent with estimates based on azimuthally-integrated HBT measurements.