Evidence of CP violation in B meson decays at the BaBar detector at SLAC, the Stanford Linear Accelerator Center, California. The computer display shows BaBar in cross-section. An electron & positron, accelerated in SLAC's PEP-II collider, annihilate at centre to produce a B meson and an anti-B meson. They live too briefly to be seen but are revealed by their decays. One decays to a kaon & three pions (red tracks), the other to a J-psi & a neutral kaon. These are also unseen, but the J/psi decays to two muons (orange tracks, right), the kaon to two pions (orange tracks, left). CP violation is the breakdown of charge & parity symmetries in certain particle interactions.