What a week. It started at SFO, in a way, and it’s ending here too. SFO is all decked out in holiday cheer – candy cane light posts, snowflakes projected on the big glass wall of the international terminal, a mock-up of the Golden Gate Bridge done in red lights – and oddly quiet now on a Friday night. I started the week here on my way to a job interview, and I’m ending it here picking up Jodi from an interview of her own. I’m looking forward to a weekend, a chance to catch up on sleep, spend time doing holiday stuff, and who knows what else.
It’s been a physics-rich week. Apart from the immersion of a job interview, there has been progress on several research fronts this week which is putting some projects in a near-ballistic trajectory toward their final results. That’s always satisfying. It’s also been a chance to look back on some of the recent successes of research in the Upsilon sample. Apart from the confirmation of the eta_b, representing an analysis tour-de-force by several core BaBar analysts this year [1] [2], the collaboration reported on new results in the search for lepton-flavor-violating decays of the Upsilon [3].
The matter-antimatter asymmetry in the universe is striking, but the cause for this vast imbalance of matter and its opposite is a deep mystery. In all the experiments we’ve been able to conduct in the lab, we cannot recreate the imbalance seen in the cosmos. In the lab – for instance, in studying K, B, or D mesons – we are able to see plenty of one of the effects needed for a cosmic antimatter deficit: CP violation. The violation of this symmetry shows up in a striking number of places. But it’s not enough.
There is hope that if we study leptons enough, we might see more CP violation there. Or, even better, we might see evidence of the violation of lepton number or baryon number, which seem to be also important ingredients in a cosmic imbalance. Alas, despite a lot of hard looking there is no evidence for this process. This isn’t to say the search is over – in fact, my colleagues who study the neutrino are hoping to test for CP violation in the neutrino system. Thanks to the discovery of neutrino flavor mixing, we know that lepton number IS violated. But it’s a tiny effect. Again, not clear how the small stuff fits into the big picture.
So I’m ending the week at SFO, waiting for Jodi and thinking about sleep, and Christmas, and neutrinos, and dark matter. And sleep.
[1] http://steve.cooleysekula.net/goingupalleys/2008/12/07/confirming-the-eta_b/
