BaBar experiment

BaBar is located at the SLAC National Accelerator Laboratory, which is operated by Stanford University for the Department of Energy in California.

BaBar was set up to understand the disparity between the matter and antimatter content of the universe by measuring Charge Parity violation.

CP violation was already predicted by the Standard Model of particle physics, and well established in the neutral kaon system (K/K meson pairs).

Currently, results are consistent with the Standard Model, but further investigation of a greater variety of decay modes may reveal discrepancies in the future.

Its large solid angle coverage (near hermetic), vertex location with precision on the order of 10 μm (provided by a silicon vertex detector), good pion–kaon separation at multi-GeV momenta (provided by a novel Cherenkov detector), and few-percent precision electromagnetic calorimetry (CsI(Tl) scintillating crystals) allow a list of other scientific searches apart from CP violation in the B meson system.

"For the BaBar experiment, higher luminosity means generating more collisions per second, which translates into more accurate results and the ability to find physics effects they otherwise couldn’t see.

Spokesperson Hassan Jawahery said: "These results were highly sought after for over 30 years and will have an important impact on our understanding of the strong interactions.

[6] While the significance of the excess (3.4 sigma) is not enough to claim a break from the Standard Model, the results are a potential sign of something amiss and are likely to impact existing theories.

At the bottom of the image, two straight lines originate from a single point (the event origin), separate by an angle of 30 or so degrees. The two line cross two grids of squares (detector grids) placed on top of each other, separated by some distance. The grid squares crossed by the lines are highlighted in different color, corresponding to the detection of the particles which crossed them.
Principle of silicon vertex detectors: the particles' origin, where the event that created them occurred, can be found by extrapolating backwards from the charged regions (red) left on the sensors.