- Is there a Higgs boson and why at 125 GeV?
Particle physicists are divided into those who think that Higgs is as good as discovered and those who think one should not say it loud. In any case, 2012 will go down in history books as the discovery year. Moreover, we will start learning something the Higgs couplings, thus kicking off with Higgs precision physics - the subject that will probably dominate particle physics for the next 2 decades.
- Is there anomalous top quark forward-backward asymmetry?
There is this persistent anomaly at the Tevatron: the direction of motion of top quarks is statistically more forward than that of antitop quarks (where forward/backward is the direction of the proton/antiproton beam); the asymmetry is 10-15% larger than predicted by the state-of-art Standard Model calculations. This year we'll get more insight into this phenomenon thanks to analyses of the full Tevatron dataset. Moreover, the LHC will narrow down on the related observable called the charge asymmetry of top pair production, and see whether any discrepancy with the Standard Model appears. If it does, it's gonna be a beautiful year. On the other hand, if nothing unusual is seen by the end of this year, that will be a big blow to our hopes that new physics is lurking there.
- Is there anomalous CP violation in the B meson sector?
Back in 2010 the D0 experiment found in their data the di-muon charge anomaly: a 1% excess of events with 2 negatively charged muons over those with 2 positively charged muons. The most appealing interpretation of that asymmetry was anomalous CP violation in B meson mixing, that is anti-B mesons turning into B-mesons more often than the other way around. However that interpretation is now under serious strain, because no CP violation has been observed by LHCb in the Bs meson decay to J/Ψ ϕ and to J/Ψ f0, and simultaneously no CP violation in the Bd meson sector has been seen in B-factories. This year LHCb should weigh in with another measurement of the difference of Bd and Bs meson CP asymmetries. That should sweep the floor once and for all, or, hopefully, open Pandora's box.
- What went wrong in OPERA?
Most physicists, including those working for the OPERA collaboration, don't think that neutrinos are superluminal (because of theoretical and indirect experimental arguments). It seems likely that the bug explaining the 60 nanosecond shift of the arrival time of neutrinos sent from CERN to Gran Sasso will be found already this year. The talk in town is that more experimental work will be done soon, with Gran Sasso's experiments ICARUS and Borexino joining in the game with independent measurements of the neutrino speed. Is it the GPS? The clock? A delay in electronics? Or is it the magic mountain?
- Is there supersymmetry below the TeV scale?
SPOILER ALERT: No. Well, so far we know for sure it's not there in its most popular incarnation, with gluino and squarks decaying via short cascades to much lighter stable neutralinos, thus producing a lot of missing energy. This year the net will be made much tighter, thanks to more data, the collision energy (likely) increased to 8 TeV, and many new analyses targeting more stealthy SUSY scenarios. By the end of this year surviving scenarios with squarks and gluinos below TeV will become collector's items, cherished for their rarity rather than beauty.
- Will there be an Armageddon on December 21?
Not sure about it, but definitely the LHC should not be running on that day. So that, if the world ends, they won't blame us.