Sunday, February 17, 2013
Room 309 (Hynes Convention Center)
[Female speaker] The apparent asymmetry of particles and antiparticles is one of the fundamental problems in cosmology. This was probably caused by symmetry breaking between particles and antiparticles just after the big bang, with cosmological antiparticles vanishing at an early stage of the universe. Local symmetry breaking is not excluded and antimatter domains could remain. Antihelium would be a key constituent of a primordial antimatter sector. Searches in the diffuse gamma-ray background for signatures of antihelium have revealed no large antimatter regions in the visible universe. Relatively small pockets of primordial antimatter are not excluded and antinuclei might reach the Earth from such regions. I shall summarize fidnings from direct searches for antihelium in cosmic rays, the most sensitive of which has recently concluded: Physical Review Letters 108, 131301 (2012)