LHC: Higgs overview

LHC Shows the Way workshop: general colloquium reviewing the LHC and the Higgs discovery.

Kyle Cramner from NYU: “We discovered the goddamned particle”
More slow live blog.

Cute opening video of LHC construction.

Factoid: kinetic energy of LHC beam is about that of a jumbo jet at cruise speed

Starting point: Standard Model is ridiculously successful, at the part per million quantitative level.
In the regime in which it is valid.

Add Higgs and you don’t just get mass, you get coupling to fermion decay is proportional to the Higgs induced mass of the fermion.

Can calculate Higgs boson production – both from strong channels, eg. gluon scattering, and from weak channels via W/Z channels.

Calculating true branching ratios (per previous blog entry) is complicated by detection efficiency of different channels.
Have to have very good model for how good you are at seeing different modes to detangle true ratios of decay modes.

Production design is a proton flux of 1034 protons per cm2 per second.
That is a lot.
Ought to produce ~ 1 Higgs every 10 seconds.

3 Tesla (30,000 gauss) magnetic field to get few km curvatures on beam.

Collisions are a mess, most of the effort is rejecting stuff that is not interesting, or could provide false positives for true signals.
Messy. Lots of hard work.
Why, yes, that could lead to other interesting signals that are not picked up, but the physicists are very clever.

LHC event spectrum fourier transform cute – red noise with a pure tone embedded corresponding to Higgs.

Lots of detail on how individual channels are extracted. Background is bootstrapped to calibrate signal.
The total significance comes from combining weak signals in many channels in both detectors.
We knew that, interesting to see it spelled out in agonizing detail.
For suitable values of interesting that is.

Nice open source toolkit ROOT for doing modern statistical analysis.

For extra bonus, spot the ROOT developer alumni who are now working in finance…

Interesting anomaly in conclusion – the ZZ channels shows anomalous spread in the mass of the virtual Z in the decay channel.
Could be signature of a negative parity Higgs.
cf Is the LHC Observing the Pseudo-scalar State of a Two-Higgs Doublet Model (arXiv)

Bonus: cute LHC zoom in