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TRIUMF | Vancouver, BC | Canada

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Higgs Seminar Liveblog from TRIUMF #2

11:44 pm PDT — Update from @Anadi, a TRIUMF physicist with the ATLAS experiment, live at CERN.

So situation is quite exciting! The only people that could enter the auditorium were there at 2AM (7 hours before the start time!). Most of the people then started lining up around 5AM and there is still a long line waiting outside the room. All other arranged areas are packed, people are discussing, excited, truly wondering what the other experiment has seen. It is a strong community feeling, I am meeting colleagues and friends I have not seen for years. Most of us are here today – to share the biggest achievement of particle physics in the past 30years.

12:02 am PDT (TM from TRIUMF)

The show starts with Director General Rolf Heuer.  Looks like he got a new haircut since his talk at @scienceworldca in early June in Vancouver.  Joe Incandella from CMS starts off…with more jokes!

Radiative corrections…square of the top mass.  This all has to do with what other measurements of other particles are used to indirectly measure the Higgs mass.

12:05 am PDT — update from @Anadi, live at CERN

When Peter Higgs entered the auditorium, big applause…two nights ago he was in CERN Restaurant 1 (the CERN ‘cantine’) and people clustered around him as he walked through – students running to get pictures.  Last night, CERN was full of students overnight, sitting on the lawn with candles, waiting for the big event. They all consider themselves extremely lucky to be here. Part of big family regardless if they worked on the higgs or not.  They are part of the biggest human endeavour…

12:11 am PDT (TM from TRIUMF)

JoeI points out the structure of the CMS detector.  It is barrel shaped and similar to ATLAS and all other collider-detectors.  Good calorimeter, meaning they can measure energy of electrons and photons very precisely. Lead-tungsten crystals.

12:14 am PDT (TM from TRIUMF)

The performance of the CMS detector actually degrades from radiation exposure but then the clever scientists can “correct” for this effect with good calibrations and modelling.  #Incandela also talks about Monte Carlo, which is the physics term for the heap of computer simulations used to benchmark and text understanding of the detector and the “known” physics.

12:18 am PDT (TM from TRIUMF)

#Incandela follows the sacred script of a particle-physics talk. State the physics, review the detector, show the performance of the detector, and then at the end…show the results.

12:20 am PDT (TM from TRIUMF)

Wow, Higgs to two photons event display!  Very elegant, very clean.  #Incandela then shows that CMS physicists “understand” the data, meaning they cross-check and compare how it works.  They also did a “blind” analysis for the 2012 new data, meaning that the physicists could not accidentally look at the “signal” until they were completely done with all the cross-checks.

He also discusses multi-variate techniques.  This means algorithms that use many different inputs that are combined to help assign weight or “value” to each event.

12:28 am PDT (TM from TRIUMF)

The first result…page 43 of the talk.  What a sweet signal plot of two photons being reconstructed to a consistent mass for a new particle!  Very elegant.

12:28 am PDT — from @Anadi, live at CERN

In the room where I am, people keep on coming sit on the floor, media are cornered. People clapped when Joe mentioned this is the work of 3,000 people for the past 10 years.

Signal just shown!  People are just astonished by the shape of the H –> gamma-gamma signal.   Quite impressive!

12:37 am PDT (TM from TRIUMF)

Interesting that CERN audience breaks into clapping for CMS result of 5.0 standard deviation significance for the combined Higgs signals.  Really an acknowledgement that is is real.  Results that are significant and bona fide.

12:37 am PDT — @Anadi, live from CERN

OK the 5 sigma has just been shown! People could not contain themselves. They just stood up, laughed, clapped…

12:48 am PDT (TM from TRIUMF)

125.3 +/- 0.6 GeV with 4.9 sigma

In five production channels, event yields in decay channels are roughly self-consistent.  Meaning that when you look across the different searches, the relative popularity of the decay modes is consistent with what you’d expect for a Higgs.

12:53 am PDT (TM from TRIUMF)

CMS concludes.

12:54 am PDT (TM from TRIUMF)

Canadians are at bat!  Or rather, ATLAS is up.  And that’s the experiment the Canadian team is part of.  Fabiola opens with requisite jokes and hints that ATLAS has got more data analyzed and understood than CMS.  Let’s see!

1:04 am PDT (TM from TRIUMF)

Three people leave our auditorium…they worked on the ATLAS analysis and know the results!  They stayed late at work tonight to hear what the “competition” (CMS) had accomplished.  Ahah!

1:05 am PDT (TM from TRIUMF)

The world lights up with press releases, comments, and new lab web pages as the full results are released! Wow…CERN even totally replaced their homepage.

1:22 am PDT (TM from TRIUMF)

Pretty careful analysis of backgrounds in the four-lepton decay channel of the Higgs.

1:31 am PDT (TM from TRIUMF)

Very attractive four-muon event and a four-electron event!  Candidates for Higgs, of course.  Clean tracks, good separation, good vertex. and then very nice exclusion plots!

1:35 am PDT (TM from TRIUMF)

Wow!  5,0 sigma and huge applause from combined gamma gamma and four lepton decay channels.  Additional checks show the results from the two separate channels are quite consistent.

1:40 am PDT (TM from TRIUMF)

Here comes the request for more data…time to study the heck out of this particle!

2:36 am PDT — @Anadi, live from CERN

Everyone is now thrilled, most of the people truly did not know about the other experiment’s results.  Lynn Evans made quite a strong statement, saying that it is the most important moment in his life. Peter higgs is here, he was just amazed by how quickly we could achieve a discovery. This is due to the excellent performance of the machine, detector, and the creativeness, dedication, enthusiasm,  ingenuity of the people in the collaboration (mainly the young collaborators).

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