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PostPosted: Tue, 13-12-11, 19:57 GMT 
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Today was another exciting day for us scientists...:

I attended the talks by both experimental LHC collaborations (ATLAS and CMS) at CERN/Geneva/Switzerland about the latest status of their intensive Higgs boson searches. The atmosphere in CERN's big auditorium was exciting, with one Nobel Prize winner (Gerard 't Hooft) and many famous physicists being present (see video below).

The Higgs boson is the only missing particle of the amazingly successful "Standard Model" of strong and electro-weak interactions. Within the Standard Model, the Higgs particle is responsible for giving mass to all matter.

The search for the Higgs particle is extremely difficult, since its experimental traces are elusive. They are predicted to appear weakly in many different interaction channels (final states).

First of all, today's presentations were an amazing testimony of the excellent performance of the LHC collider during the past year, for which the close collaboration of thousands of people was responsible! By now, the mass window for a possible discovery of the Higgs has been shrunk experimentally to a narrow region between 115 and ~130 GeV. In addition, first evidence was reported by both groups that the Higgs boson might have been spotted in form of a mild excess of events around a mass of ~ 125 GeV. However, more data taking is necessary in 2012, before one can expect a more clearcut statement:

either in form of the Higgs discovery or the confirmation of just a statistical fluctuation ...

Here is today's press release that might suffice for most readers.
http://press.web.cern.ch/press/PressRel ... 5.11E.html

Have a look at these two videos, giving a feeling about the excitement and about the huge efforts that are required for a possible Higgs discovery...

A roll: http://cdsweb.cern.ch/record/1406052
B roll: http://cdsweb.cern.ch/record/1406051

Both videos also contain scenes from the beginning of today's talks at CERN by Fabiola Gianotti (ATLAS spokesperson) and Guido Tonelli (CMS spokesperson).

It may be best to download the videos before playing them, since the lines are pretty busy ;-)

The white-haired physicist at the beginning of the video (Roll A) is Prof. Rolf Heuer, the Director General of CERN. Before his CERN appointment, he was my boss, as director of research of my laboratory (Deutsches Elektronen Synchrotron (DESY)/Hamburg).

Some more concrete statements about today's results you find here

ATLAS:
http://www.atlas.ch/news/2011/status-re ... -2011.html

CMS:
http://cms.web.cern.ch/news/cms-search- ... 0-and-2011

As soon as the talks or papers will be available, I'll add the links in this thread.


Fridger

Golden Channel: Higgs --> ZZ(*) --> μ+ μ- μ+ μ-
2 events were seen and the Higgs mass reconstructed to ~ 125 GeV!

Image
Figure and Caption from http://www.atlas.ch/news/2011/status-re ... -2011.html

ATLAS event containing four muons. This event is consistent with coming from two Z particles decaying: both Z particles decay to two muons each. Such events are produced by Standard Model processes without Higgs particles. They are also a possible signature for Higgs particle production, but many events must be analysed together in order to tell if there is a Higgs signal. This view is a zoom into the central part of the detector. The four muons are picked out as red tracks. Other tracks and deposits of energy in the calorimeters are shown in yellow.


Last edited by t00fri on Fri, 16-12-11, 21:30 GMT, edited 6 times in total.

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PostPosted: Tue, 13-12-11, 20:40 GMT 
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Héhé... This morning I was reading an article in Le Monde about this news... and of course I could not avoid thinking in you... :o

:D


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PostPosted: Tue, 13-12-11, 21:07 GMT 
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ElChristou wrote:
Héhé... This morning I was reading an article in Le Monde about this news... and of course I could not avoid thinking in you... :o

:D


Hehe!

nice reading you and knowing that you're thinking of me occasionally ;-)

BUT, the relevant talks at CERN started only at 14:00 today with striktly no leaks to the public before that time. So Le Monde could only have described the much more vage situation before today.

Cheers,
Fridger


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PostPosted: Tue, 03-07-12, 17:41 GMT 
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Hi all,

tomorrow morning, July 4th, (7:0 UTC <=> 9:0 CEST) CERN will give an update on the Higgs search as curtain raiser to the ICHEP conference (the 36th International Conference on High Energy Physics in Melbourne, Australia from 4-11 July, 2012).. The rumors seem to point to an imminent anouncement of the Higgs discovery tomorrow. But even in case it's not going to be a formal announcement of discovery, the probablity is high that the long sought Higgs particle has been essentially located.

Stay tuned. More here by tomorrow....

Fridger


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PostPosted: Tue, 03-07-12, 17:53 GMT 
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I assume you've heard of the leak of a video that they'd prepared.

http://www.telegraph.co.uk/science/larg ... ticle.html

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PostPosted: Tue, 03-07-12, 22:14 GMT 
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Selden wrote:
I assume you've heard of the leak of a video that they'd prepared.

http://www.telegraph.co.uk/science/larg ... ticle.html


Yes, but such videos might typically also be prepared in advance to cover various possible alternatives... It's only the official talks/papers that count. At this time, it seems quite probable that a new particle has left its traces in the CERN detectors. Yet, what is harder to answer before the official release is whether this new particle is precisely the Higgs particle of the Standard Model!

Fridger


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PostPosted: Wed, 04-07-12, 8:40 GMT 
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Here is an excellent video (dated July 3rd), where an old friend and famous colleaque of mine, Prof. John Ellis, explains some of the crucial issues associated with the claim of a Higgs discovery. John provides a perfectly balanced overview of the present excitement on the one hand and some remaining general reservations on the other.

http://youtu.be/fE_Qw_nsMU8

John has been a permanent staff member of the CERN Theory Division for many years and currently -- after his formal retirement-- is Clerk Maxwell Professor of Theoretical Physics at King's College London. He is both a Fellow of the Royal Society (FRS) and also was awarded the Most Excellent Order of the British Empire (CBE).


Fridger


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PostPosted: Wed, 04-07-12, 9:18 GMT 
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The historic update presentation at CERN in the search for the Higgs boson just ended. It was a memorable event and the strength of the applause was comparable to what is familiar at distinguished soccer games ;-)

Many famous physicists were present. At the end of the CERN seminar both Peter Higgs
Image

and François Englert (who is another "father" of the Higgs mechanism) made some emotional comments.

Here is a quote from CERN concerning the state of affairs as of this morning:

Both ATLAS and CMS gave the level of significance of the result as 5 sigma on the scale that particle physicists use to describe the certainty of a discovery. One sigma means the results could be random fluctuations in the data, 3 sigma counts as an observation and a 5-sigma result is a discovery. The results presented today are preliminary, as the data from 2012 is still under analysis. The complete analysis is expected to be published around the end of July.

During our lunch conversations preceeding today's official announcements, we mostly assumed a 4 sigma evidence for the Higgs, as was conveyed by various rumors. Apparently, due to the amazing performance of the LHC machine it was finally possible to push the significance up to a 5 sigma level which is a prerequisite for announcements of experimental discoveries!

The Higgs mass is still at the originally suspected value of 126 GeV.

Here is the official text of the CERN press release from right after the update presentation (July 4th, 11:00 CEST):

http://press.web.cern.ch/press/PressRel ... 7.12E.html

Fridger


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PostPosted: Thu, 05-07-12, 4:24 GMT 
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Do you have any links to videos of this latest presentation?
I saw a short news-byte which showed a shot of Peter Higgs in the audience (looking somewhat emotional I must say!).

I imagine some people involved will likely be Nobel Laureates soon (hopefully Peter Higgs included!)

CC

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PostPosted: Thu, 05-07-12, 10:04 GMT 
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chuft-captain wrote:
Do you have any links to videos of this latest presentation?
I saw a short news-byte which showed a shot of Peter Higgs in the audience (looking somewhat emotional I must say!).

I imagine some people involved will likely be Nobel Laureates soon (hopefully Peter Higgs included!)

CC


CC,

the video of the Higgs-update seminar of July 4th has been announced already, but at this time is not yet available. Here is the URL. Just stay tuned there...
http://cdsweb.cern.ch/record/1459513?ln=en

Actually, at the end of yesterday's event, Peter Higgs was given a tissue to wipe off his tears...Quite understandable, actually. The Higgs boson was hunted experimentally for almost 50 years, i.e. a large part of Peter Higgs' lifetime. He was particularly moved by the fact that he was still alive to personally enjoy this triumph of a perfectly correct and most basic theoretical prediction!

If you are mainly interested in yesterday's physics results with actual plots, here is a nice live blog by a former postdoc (Adam Falkowski/ Orsay) of my theoretical physics department :

++++++++++++++++++++++++++++++
http://resonaances.blogspot.de/
++++++++++++++++++++++++++++++

Note: NO typo here: /resonaances!

Note also this quote from the resonaances site:

Résonaances is a particle physics blog from Paris. It's about the latest news and gossips in particle physics and astrophysics. The posts are often spiced with sarcasm, irony, and a sick sense of humor. The goal is to make you laugh; if it makes you think too, that's entirely on your own responsibility...

Fridger


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PostPosted: Thu, 05-07-12, 12:47 GMT 
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Thanks for the links Fridger,

BTW. I think Leon Lederman's "The Invisible Soccer Ball" analogy (Chapter 1 in: The God Particle: If the Universe Is the Answer, What Is the Question?)
is an excellent description (at least for the layman) of the investigative process use by quantum physicists.

A better read also IMO, than "A Brief History of Time", speaking of which, I see that Stephen Hawking has now said he will repay his wager to Gordy Kane, however it seems that his speaking machine mysteriously translated 100 pounds into 100 dollars when referring to the repayment. Perhaps a quantum glitch in his computer? :wink:

From: http://www.guardian.co.uk/science/2007/nov/17/sciencenews.particlephysics...
Quote:
In summer 2000, scientists working on the collider saw what looked like the first glimpse of the God particle. It was tantalising, but not enough to claim a discovery. They needed more time to prove it, but there was none. The collider was due to shut in a few months, to be replaced by a more powerful machine.

That September, at a restaurant on the island of Jeju, off the southern tip of the Korean peninsula, one of the odder events in the hunt for the Higgs particle was about to play out. Gordy Kane, now director of the Michigan Centre for Theoretical Physics, was discussing the glimpse of the God particle that had been reported at Cern. During the discussion that followed, a familiar voice cut in, offering to bet £100 that the Higgs particle would never be found, at Cern or anywhere else. It was Stephen Hawking. Kane accepted the wager. "It was a bit of a cheek," says Higgs, who believes Hawking was not familiar enough with the physics to back up his view.

At Cern, the scientists won a temporary reprieve. They crashed more particles and stared at more traces, but the glimpse never became anything more. In November 2000, the machine was switched off, triggering outrage among many who felt physics' most-wanted prize had been snatched from their grasp. Kane sent a cheque for £100 to Cambridge, but he expects his money back soon.

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PostPosted: Fri, 06-07-12, 8:54 GMT 
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Here are some essential sequences from the archived webcast seminar about the Higgs-Update of July 4th:

http://cdsweb.cern.ch/record/1459510

This video has been recorded on July 3rd with modifications added on July 5th.

It includes some crucial plots about the physics results obtained by the two experimental collaborations ATLAS and CMS. The full record of the webcast seminar of July 4th is still not yet available.

Here is the video of the press conference that followed right after that announcement event on July 4th:

http://cdsweb.cern.ch/record/1459512

Incidentally, Prof. Rolf Heuer was Director of Research at my lab (DESY) in Hamburg before becoming Director General of CERN.

Fridger


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PostPosted: Fri, 06-07-12, 13:03 GMT 
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And a short and interesting series of comments by Peter Higgs, Francois Englert, Carl Hagen and Gerald Guralnik:

http://cdsweb.cern.ch/record/1459523

Quite late in the press conference (from your link above), Prof. Rolf Heuer said that they were "metaphorless" in response to a request to provide a metaphor(s) for the "god particle" (49:30), yet I thought he had already provided a rather excellent metaphor quite early in the session (08:25) in describing the clustering of journalists around Peter Higgs as making him a very "heavy" guy. :)

I thought the best question of all was: "what happened to the graviton" from Melbourne. (52:00). :lol:

I also thought that one of the best questions came at the very end (58:30). I thought this was a great question as it went to the very fundamental justifications for doing science.
He asked how to justify the budget spent on this type of pure physics project, versus more immediate humanistic issues such as addressing poverty, vaccines, etc, in the context of europe's current fiscal issues, and his own situation in coming from a developing country.
This was also I thought well answered by the professor, with regard to maintaining the balance between fundamental and applied science, and the complementary feedback loop that benefits both (although I'm sure it's not the first time he's had to answer this type of question :wink: ).
His example of the WWW coming out of their need to collaborate was quite a good example, but he could have IMHO broadened this to point out that many of the beneficial technologies which we now have (MRI machines, lasers, etc) only exist on the shoulders of the earlier work of people such as Einstein, Rutherford, Curie, Faraday, Bohr, Dirac, Heisenberg (to mention a few), and in turn the very discoveries we are seeing in fundamental science today (from the Human Genome project, to the LHC itself), would not be possible without the very tools (micro-processors, electronics, lasers, etc) which have resulted from the practical application of those earlier "blue sky" researche(r)s.

I just hope that if this discovery does result in a great-leap forward, that we (ie. the politicians funding this work) have the wisdom and hindsight to use it for constructive, rather than destructive purpose.
Remember that the last event of this significance (which I would say was the splitting of the atom) resulted in atomic bombs as well as nuclear energy.
History suggests that human nature has a preference for development of weapons technology ahead of beneficial technology from any new discovery.
eg. Stone Age weapons probably came before flints for making fire.
The mastery of chemicals probably resulted in explosives before the development of anything else.
The atomic age (I've already mentioned).
If this discovery signals a new era (let's call it the "Age of Gravity") I hope that we have the wisdom and self-control to develop peaceful applications from whatever advances result from this.

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PostPosted: Sat, 07-07-12, 1:12 GMT 
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Hi Chuft; I wondered what a common mortal could do with the Higgs' boson and my auto-replay is: nothing. Common mortals does nothing with pions, muons etc. mostly because they decays fastest. A TV telecommand with pions would do the man stand up from chair to push up the channels' button to watch the TV.

P.S.
As for the medical applications, be caution with the positron emission tomography (PET), since the radiography of your brain is accomplished through the gamma-ray scattering between antimatter's interaction (the positrons of the machine and your brain's electrons). Then it was just the LSD which flashed the head!


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PostPosted: Sat, 07-07-12, 9:43 GMT 
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fenerit wrote:
Hi Chuft; I wondered what a common mortal could do with the Higgs' boson and my auto-replay is: nothing. Common mortals does nothing with pions, muons etc. mostly because they decays fastest. A TV telecommand with pions would do the man stand up from chair to push up the channels' button to watch the TV.

P.S.
As for the medical applications, be caution with the positron emission tomography (PET), since the radiography of your brain is accomplished through the gamma-ray scattering between antimatter's interaction (the positrons of the machine and your brain's electrons). Then it was just the LSD which flashed the head!


Clearly the benefits of the Higgs particle do NOT belong to the field of APPLIED science ;-) . Yet the Higgs boson plays a most fundamental double role in our celebrated Standard Model of the World:
  • On the one hand, the Higgs boson constitutes the origin of mass for all elementary particles and hence of the Universe, including our own and foreign galaxies! The underlying mechanism, called "Spontaneous Symmetry Breaking" is also well-known in many other areas of physics.

  • On the other hand, the Higgs boson causes a cancellation of unphysical infinities in the Standard Model such as to render it perfectly finite, well-defined and hence renormalizable as we say... Hence, for mathematical consistency of the Standard Model, the Higgs boson must exist! Therefore, the triumph and relief that it has actually been found should be well understandable.


Fridger


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