Archive for Higgs Boson

The 2013 Nobel Prize for Physics .. goes to Englert and Higgs

Posted in Science Politics, The Universe and Stuff with tags , , , , , , on October 8, 2013 by telescoper

Well, there we are. After an excruciating (and unexplained) delay the 2013 Nobel Prize for Physics has gone to François Englert and Peter Higgs. You can find the full press release here; the first section of text reads:

François Englert and Peter W. Higgs are jointly  awarded the Nobel Prize in Physics 2013 for the  theory of how particles acquire mass. In 1964, they  proposed the theory independently of each other  (Englert together with his now deceased colleague  Robert Brout). In 2012, their ideas were confirmed  by the discovery of a so called Higgs particle at the  CERN laboratory outside Geneva in Switzerland. The awarded theory is a central part of the Standard  Model of particle  hysics that describes how the world is  constructed. According to the Standard Model, every­thing, from flowers and people to stars and planets,  consists of just a few building blocks: matter particles.  These particles are governed by forces mediated by force  particles that make sure everything works as it should. The entire Standard Model also rests on the existence  of a special kind of particle: the Higgs particle. This  particle originates from an invisible field that fills up  all space. Even when the universe seems empty this  field is there. Without it, we would not exist, because  it is from contact with the field that particles acquire  mass. The theory proposed by Englert and Higgs  describes this process.

Anyway, congratulations to the two Laureates. I did get a bit excited when the rumour started that the winner this year would be someone born in Newcastle upon Tyne whose first name is Peter, but I guess I’ll have to wait until next year..

Oh, and François Englert is the first ever Belgian winner of the Nobel Prize for Physics!

I have to head off to London for a Parliamentary Reception organized by the Science & Technology Facilities Council, so I’ll have to leave it there but please feel free to add reactions to the announcement via the Comments Box.

P.S. Yesterday’s poll is now closed.

Physics Nobel Betting

Posted in Science Politics, The Universe and Stuff with tags , , , , , , , on October 7, 2013 by telescoper

I’m back in circulation just in time for tomorrow’s announcement of the 2013 Nobel Prize for Physics. The smart money is going on an award for the discovery of the Higgs Boson, but to whom should it be awarded. Today’s Grauniad summarizes the difficulties thus:

The committee can contrive the wording of the prize to narrow the number downwards and this is likely to happen. The prize could go to François Englert, who published the idea first, and Peter Higgs, who was second, but crucially was first to flag up the new particle. But that would rebuff the trio of Gerald Guralnik, Carl Richard Hagen and Tom Kibble, who developed the theory separately and published just a month after Higgs. The possibility has already caused acrimony among the scientists. Guralnik and Hagen, two US researchers, believe European physicists have conspired to erase their contribution from history.

This doesn’t seem to me to be entirely accurate, though. As far as I understand it, Higgs was the only one of the names above to mention a massive scalar particle, There is, I believe, therefore a strong case that the Nobel Prize should be awarded to Peter Higgs outright. Or if not to him, to some other person called Peter who was born in the North East…

However, I am used to being in a minority of one so there will undoubtedly be many others who feel differently.  Time for a poll! This one is different from my usual ones, in that you are allowed to vote more than once. Please use up to three votes: if you think Peter Higgs should win it outright vote three times for him. If you think it should be a three way split then vote for three different people, etc.

I should say that I don’t think the Nobel Committee for Physics is allowed to make an award to an institution such as CERN, but I’ve left that option in to see whether folks think that tradition should change..

UPDATE: Here are the Thomson-Reuters predictions, including Marcy, Mayor and Queloz for Extra Solar Planets…

 

Probing the Higgs-like Particle

Posted in The Universe and Stuff with tags , , on November 21, 2012 by telescoper

After my little dabble in particle physics yesterdays I thought I’d reblog this from a proper particle physicist – it’s a long and rather technical post about the Higgs-like Boson recently discovered at the LHC. Enjoy.

Collider Blog

We are in the process of ascertaining the properties of the Higgs-like particle discovered by CMS and ATLAS last July 4th. It must be a boson because it decays to pairs of bosons. Since it decays to a pair of massless photons, it cannot be spin-1. The relative rates of decays to WW and ZZ on the one hand, and γγ on the other, are close to what is expected for spin-0 boson and not what is expected for a spin-2 graviton. John Ellis, Veronica Sanz and Tevong You wrote a nice paper about this earlier this week (arXiv:1211.3068, 13-Nov).

So let’s assume that the new particle X(126) is a Higgs boson (and I will use the symbol “H” for it). If it is the standard model Higgs boson, then its CP eigenvalue must be +1. If it is a member of a two-Higgs-doublet model, then its CP…

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A Nobel Book

Posted in Science Politics, The Universe and Stuff with tags , , , , , , , , , on October 8, 2012 by telescoper

The announcement this morning of the 2012 Nobel Prize for Medicine or Physiology reminded me that tomorrow will see the announcement of the 2012 Nobel Prize for Physics. This is due to happen tomorrow morning at 11.45 CET (which I think is 10.45 BST) or thereabouts. It would be unseemly to speculate on the outcome, of course, so that’s what I’ll do.

Although the discovery of a scalar particle at the Large Hadron Collider that may well be the Higgs boson happened only recently, and is yet to be definitively proven to be the Higgs, the smart money has to be on an award relating to that, presumably to Peter Higgs. However, given that the award can go to up to three individuals, who else might earn a share? Gerald Guralnik, Tom Kibble and Carl Richard Hagen came up with the same idea about the same time as Higgs, but all four of them can’t win according to the rules. Answers to that little conundrum on a postcard…

But of course the Prize might go to something else altogether. An interesting bet would be Alain Aspect for his important work on experimental studies of quantum entanglement. Also with an outside chance is Sir Michael Berry for his brilliant work on the Geometric Phase.

That’s by no means an exhaustive list of runners and riders, but I have to get back to business now. I’d be interested to have further nominations via the comments box and will of course be getting an early night ahead of the expected phone call from Stockholm tomorrow morning…

What’s with the Wang Particle?

Posted in Astrohype, The Universe and Stuff with tags , , , , , , on September 11, 2012 by telescoper

Not long ago a colleague ran into my office all of a flutter and asked me about this new discovery called the “Wang particle” that had been in the media. I’m the one around here who’s supposed to know about particle astrophysics stuff, so I was quite embarrassed that I’d never heard of the Wang particle, although I’ll be delighted if it becomes famous as the name has a great deal of comedy potential.

Anyway, I vowed to find out a little bit about it and finally got around this lunchtime to doing so. It turns out that the story was sparked by press release from the British Science Association which, out of the goodness of my heart, I reproduce below (link added by me).

 A new particle, similar to the Higgs Boson, could provide a clue to one of the greatest mysteries of the Universe.

Dr Charles Wang from the University of Aberdeen believes that a new scalar particle is behind the intense supernova explosions that occur when a star implodes. He presented his work to the British Science Association on Tuesday.

Supernova explosions are the most powerful forces in the universe, second only to the Big Bang.

Once frequent, the energy produced in these explosions is responsible for combining particles to produce all the recognisable elements on earth, providing all the known building blocks of life on earth.

There are still many gaps in our understanding of physics and one of the major blanks is how the implosion of a star subsequently produces an intense explosion.

It is known that as elements are created at the centre of a star, a huge amount of energy is released.  However, it is believed that the conversion of known elements would never produce enough energy to result in an explosion.

Dr Wang’s theory states that “a scalar particle – one of the most elementary types of particles in the universe and similar to the Higgs Boson – is at work within these stars and responsible for the additional energy which causes the explosion to take place.”

The scalar particle would effectively enable the high transfer of energy during a supernova, allowing shockwaves from the implosion of a star to become re-energised and cause an explosion.

A new collaboration between Dr Wang and CERN could provide the equipment to make this theory a reality and demonstrate the existence of the ‘Wang particle’ – or as Dr Wang himself refers to it the ‘scalar gravitational particle’. It is hoped that using the ISOLDE facility at CERN it may be possible assimilate a nuclear reaction that would determine the process of a starburst.

If demonstrated, the existence of the ‘Wang particle’, like the Higgs Boson, would hold major implications for physics, shedding new light on the theory of everything and affecting our understanding of how different physical phenomena interact.

There’s no link to an academic paper with it, which is a bit disappointing, but an older piece in the CERN Courier does provide a reference to the paper, which is

C H-T Wang et al. 2011 Parametric instability induced scalar gravitational waves from a model pulsating neutron star, Phys. Letts. B 705 148

If you’re prepared to shake hands with the Devil that is Elsevier you can find the paper here.

I have to confess that this is a new one on me. I haven’t gone through the paper in detail yet but, at a quick skim, it seems to be based on a variation of the  Brans-Dicke scalar-tensor theory of gravity. It’s probably an interesting paper, and I look forward to reading it in detail on a long flight I’m about to take, but I am a bit mystified as to why it created such a stir in the media. Looks more a result of hype than real significance to me. It certainly isn’t the “new Higgs boson” anyway. Nor is it likely to be relevant in explaining Climate Change. Or am I missing something? Perhaps hot air generated by press releases is responsible for global warming?

Anyone out there an expert on Wang’s work? Care to comment?

Short but sweet – Higgs (1964)

Posted in The Universe and Stuff with tags , , , , on August 31, 2012 by telescoper

In the light of all this Malarkey about the (claimed) discovery of the Higgs Boson at the Large Hadron Collider, I thought you might be interested to see the original paper by Higgs (1964) in its entirety. As you can see, it’s surprisingly small. The paper, I mean, not the boson…

p.s. The paper is freely available to download from the American Physical Society website; no breach of copyright is intended.

p.p.s. The manuscript was received by Physical Review Letters on 31st August 1964, i.e. 48 years ago today.

The Low-down on the LHC Boson

Posted in Open Access, The Universe and Stuff with tags , , , , , , on August 2, 2012 by telescoper

Although it’s a little late I thought I’d just put up a brief post to draw your attention to the news that a couple of technical papers have appeared on the arXiv giving updated details of the recent discovery at the Large Hadron of a new scalar particle that could be the Higgs boson. I don’t think it’s yet absolutely proven that this is what the new particle is, which is why I’ve called it the “LHC boson” in the title.

The ATLAS paper reports the detection of a Higgs-like particle with a 5.9 sigma confidence level, up from the 5.0 sigma reported on July 4. Here’s the abstract:

A search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities of approximately 4.8 fb^-1 collected at sqrt(s) = 7 TeV in 2011 and 5.8 fb^-1 at sqrt(s) = 8 TeV in 2012. Individual searches in the channels H->ZZ^(*)->llll, H->gamma gamma and H->WW->e nu mu nu in the 8 TeV data are combined with previously published results of searches for H->ZZ^(*), WW^(*), bbbar and tau^+tau^- in the 7 TeV data and results from improved analyses of the H->ZZ^(*)->llll and H->gamma gamma channels in the 7 TeV data. Clear evidence for the production of a neutral boson with a measured mass of 126.0 +/- 0.4(stat) +/- 0.4(sys) GeV is presented. This observation, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7×10^-9, is compatible with the production and decay of the Standard Model Higgs boson.

The paper from CMS reinforces the discovery of a Higgs-like particle with a mass of 125 GeV at a 5-sigma level of confidence:

Results are presented from searches for the standard model Higgs boson in proton-proton collisions at sqrt(s)=7 and 8 TeV in the CMS experiment at the LHC, using data samples corresponding to integrated luminosities of up to 5.1 inverse femtobarns at 7 TeV and 5.3 inverse femtobarns at 8 TeV. The search is performed in five decay modes: gamma gamma, ZZ, WW, tau tau, and b b-bar. An excess of events is observed above the expected background, a local significance of 5.0 standard deviations, at a mass near 125 GeV, signalling the production of a new particle. The expected significance for a standard model Higgs boson of that mass is 5.8 standard deviations. The excess is most significant in the two decay modes with the best mass resolution, gamma gamma and ZZ; a fit to these signals gives a mass of 125.3 +/- 0.4 (stat.) +/- 0.5 (syst.) GeV. The decay to two photons indicates that the new particle is a boson with spin different from one.

I’ll refrain from commenting on the use of frequentist language in both these papers, but instead just comment that these extremely important papers are available for free on the arXiv. Open access, we call it.

PS. There’s an interesting blog post related to these papers, about citations in particle physics here.

The Higgs? A Definite Maybe..

Posted in The Universe and Stuff with tags , , , , , , on July 4, 2012 by telescoper

This is really something for expert particle physicists to blog about, but I couldn’t resist saying something about this morning’s dramatic physics news.

Well, after yesterday’s preview here is the actual press release from CERN:

Geneva, 4 July 2012. At a seminar held at CERN1 today as a curtain raiser to the year’s major particle physics conference, ICHEP2012 in Melbourne, the ATLAS and CMS experiments presented their latest preliminary results in the search for the long sought Higgs particle. Both experiments observe a new particle in the mass region around 125-126 GeV.

“We observe in our data clear signs of a new particle, at the level of 5 sigma, in the mass region around 126 GeV. The outstanding performance of the LHC and ATLAS and the huge efforts of many people have brought us to this exciting stage,” said ATLAS experiment spokesperson Fabiola Gianotti, “but a little more time is needed to prepare these results for publication.”

“The results are preliminary but the 5 sigma signal at around 125 GeV we’re seeing is dramatic. This is indeed a new particle. We know it must be a boson and it’s the heaviest boson ever found,” said CMS experiment spokesperson Joe Incandela. “The implications are very significant and it is precisely for this reason that we must be extremely diligent in all of our studies and cross-checks.”

“It’s hard not to get excited by these results,” said CERN Research Director Sergio Bertolucci. “ We stated last year that in 2012 we would either find a new Higgs-like particle or exclude the existence of the Standard Model Higgs. With all the necessary caution, it looks to me that we are at a branching point: the observation of this new particle indicates the path for the future towards a more detailed understanding of what we’re seeing in the data.”

The results presented today are labelled preliminary. They are based on data collected in 2011 and 2012, with the 2012 data still under analysis.  Publication of the analyses shown today is expected around the end of July. A more complete picture of today’s observations will emerge later this year after the LHC provides the experiments with more data.

The next step will be to determine the precise nature of the particle and its significance for our understanding of the universe. Are its properties as expected for the long-sought Higgs boson, the final missing ingredient in the Standard Model of particle physics? Or is it something more exotic? The Standard Model describes the fundamental particles from which we, and every visible thing in the universe, are made, and the forces acting between them. All the matter that we can see, however, appears to be no more than about 4% of the total. A more exotic version of the Higgs particle could be a bridge to understanding the 96% of the universe that remains obscure.

“We have reached a milestone in our understanding of nature,” said CERN Director General Rolf Heuer. “The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particle’s properties, and is likely to shed light on other mysteries of our universe.”

Positive identification of the new particle’s characteristics will take considerable time and data. But whatever form the Higgs particle takes, our knowledge of the fundamental structure of matter is about to take a major step forward.

There’s a hive of internet activity related to this announcement, and I can’t possibly link to all the excellent expert commentary going on, but for details you can do no better that Sean Carroll’s live blog from Geneva or the Guardian’s live blog.

In a nutshell, there’s definitely something in both CMS and Atlas data which, if it really is a new particle,  is definitely a boson and which weighs in around 125 GeV. The two-photon decays are consistent with what a standard model Higgs boson would be expected to produce, for example. The consistency between the two experiments is very compelling.

The overall level of significance is around 5σ. I’ll refrain from making churlish comments about the frequentist language and just say that the LHC certainly seems to have detected something that could definitely be the Higgs. This is genuinely exciting because it has come more quickly than most people expected. That’s a tribute to the LHC teams, I’d say.

However, it isn’t yet proven that the Higgs what this particle is. If it’s a new particle that’s not the Higgs that could be even more interesting. To establish the identity of the particle that has been discovered will require a lot more work,  looking at much more detailed aspects of its behaviour as revealed by collision data. But it’s certainly possible that it is the Higgs, and I venture to suggest that’s what most particle physicists think it is.

So a discovery. A palpable discovery. Now comes the exploration…

Higgs Preview

Posted in Science Politics, The Universe and Stuff with tags , , , , , , on July 3, 2012 by telescoper

I’m a bit slow to post anything about the ongoing bout of Higgs-steria that’s been engulfing the interwebs in recent days. Even Andy Lawrence got there ahead of me.  What’s caused all the commotion is an announcement about an announcement from CERN at a special seminar tomorrow (Wednesday 4th July) at 9am CEST, which is 8am British “Summer” Time.  Here’s a bit of the press release:

CERN will hold a scientific seminar at 9:00 CEST on 4 July to deliver the latest update in the search for the Higgs boson. At this seminar, coming on the eve of this year’s major particle physics conference, ICHEP, in Melbourne, the ATLAS and CMS experiments will deliver the preliminary results of their 2012 data analysis.

“Data taking for ICHEP concluded on Monday 18 June after a very successful first period of LHC running in 2012,” said CERN’s Director for Accelerators and Technology, Steve Myers. “I’m very much looking forward to seeing what the data reveals.”

The 2012 LHC run schedule was designed to deliver the maximum possible quantity of data to the experiments before the ICHEP conference, and with more data delivered between April and June 2012 than in the whole 2011 run, the strategy has been a success. Furthermore, the experiments have been refining their analysis techniques to improve their efficiency in picking out Higgs-like events from the millions of collisions occurring every second. This means that their sensitivity to new phenomena has significantly increased for both years’ data sets.  The crunching of all this data has been done by the Worldwide LHC Computing Grid, which has exceeded its design specifications to handle the unprecedented volume of data and computing.

“We now have more than double the data we had last year,” said CERN Director for Research and Computing, Sergio Bertolucci, “that should be enough to see whether the trends we were seeing in the 2011 data are still there, or whether they’ve gone away. It’s a very exciting time.”

I won’t try to repeat what’s been said better and more authoritatively elsewhere; a nice collection of video material at the STFC website and a piece by Sean Carroll (also here) are worth mentioning if you’re not up on why the Higgs Boson is so important.

I wrote  a rather facetious post about the last episode of Higgs-mania way back in December because I found the actual announcement to be a bit of a damp squib and the associated hype rather irritating. This time there are even more rumours flying around – not to everyone’s approval – but it’s obviously best to wait and see what is actually announced rather than comment on them.

The main question in my mind is whether it’s sufficiently interesting to get up in time to watch the seminar 8am tomorrow morning…

Brian Cox is 44.

The Higgs Buzz

Posted in The Universe and Stuff with tags , , , , on June 19, 2012 by telescoper

Reaction to rumours about the Higgs, and a not-entirely good-tempered comment thread about the ethics of blogging. All in a day’s work for a particle physicist, I guess! Read the inside story on this post…

..and if you read this article you’ll see where the rumour originated.

Of Particular Significance

The rumors about the Higgs particle at the Large Hadron Collider [LHC] have begun again, and since that’s all anyone is going to want to talk about until we actually get the news for real, at the ICHEP conference in Melbourne in a couple of weeks, we may as well get started.

[This is especially true since we learned last year that some well-known non-particle-physicist bloggers have information pipelines directly into the experiments.  It is perhaps inevitable that there are scientists who see it in their best interest to subvert the scientific process.]

The current hot rumor is that the LHC experiments ATLAS and CMS have seen, in the new 2012 data, very roughly what they saw last December in the 2011 data, at least as far as the signal from a Higgs decaying to two photons (particles of light) in the mass range of 125 GeV/c2

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