Archive for Particle Physics

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…

 

Neutrino Physics in a Small Universe

Posted in Biographical, The Universe and Stuff with tags , , , , , , , on April 23, 2013 by telescoper

I’ve only just got time for a quick lunchtime post before I head off to attend an afternoon of Mathematics presentations, but it’s a one of those nice bits of news that I like to mention on here from time to time.

It is my pleasure to pass on the wonderful news that one of my colleagues in the School of Mathematical and Physical Sciences here at the University of Sussex,  Dr Jeff Hartnell,. has been awarded  the High Energy Particle Physics prize of the Institute of Physics, which means that his name has now been added to the illustrious list of previous winners. The prize is awarded annually by the HEPP Group, a subject group in the Nuclear and Particle Physics Division of the IOP, to a researcher in the UK who has made an outstanding contribution to their field of study early in their career (within 12 years of being awarded their first degree).

There’s a very nice piece about this award here which reveals, amongst other things, that many moons ago at Nottingham I was Jeff’s undergraduate tutor! In fact Jeff also attended a third-year course on Theoretical Elementary Particle Physics I taught in those days. That he survived those experience and went on to be a world-leading physicist speaks volumes! Not only that, it’s also evidence that the world of physics is smaller than we sometimes suppose. I’ve crossed paths with a number of my new colleagues at various times in the past, but it’s particularly rewarding to see someone you taught as an undergraduate go on to a highly successful career as a scientist. Jeff was awarded a prestigious ERC grant this year too!

Jeff is currently in the USA helping to set up the largest-ever experiment in neutrinos to be built there, called NOvA. You can click on the preceding links for more technical details, and I also found this interesting video showing the NOvA detector being assembled. Particle physics experiments are never small, are they?

p.s. Why do they insist on writing “metric ton” instead of “tonne”?

Should UK Research Funding Be Reorganized?

Posted in Finance, Science Politics with tags , , , , , , , , , , on April 13, 2013 by telescoper

A couple of recent news items spurred me on to reflect a bit about the system of research funding in the UK. The first of these was an item I noticed a while ago in Research Fortnight about the (ongoing) Triennial Review of the research councils, and specifically, input from the Wellcome Trust to that review that was rather critical of the Science and Technology Facilities Council and suggested it might be dismantled.

For context it’s probably a good idea to look back to the formation of STFC in 2007 via the merger of the Particle Physics and Astronomy Research Council (PPARC) and the Council for the Central Laboratories of the Research Councils (CCLRC). Previously, PPARC had looked after particle physics and astronomy (including space science) and CCLRC had run large experimental facilities in other branches of science. The idea of merging them wasn’t silly. A large chunk of PPARC’s budget went on managing large facilities, especially ground-based astronomical observatories, and it was probably hoped that it would be more efficient to put all these big expensive pieces of kit under the same roof (so to speak).

However, at the time, there was considerable discussion about what should happen in general with science grants. For example, physicists working in UK universities in areas outside astronomy and particle physics previously obtained research grants from the Engineering and Physical Sciences Research Council (EPSRC), along with chemists, engineers and even mathematicians. Some experimentalists working in these areas used facilities run by the CCLRC to do their work. However, astronomers and particle physicists got their grants from PPARC, the same organisation that ran their facilities and also paid subscriptions to international agencies such as CERN and ESA. These grants were often termed “exploitation”  or “responsive mode” grants; they involved funding for postdoctoral researchers and staff time used in analysing observational or experimental data and comprised relatively little money compared the the cost of the PPARC facilities themselves. PPARC also funded PhD studentships and postdoctoral fellowships under the umbrella of its Education and Training division, although needless to say all the Education and Training involved was done in host universities, not by PPARC itself.

The question was whether the new merged organisation, STFC should continue giving grants to university groups or whether the responsibility for doing this should be moved elsewhere, perhaps to EPSRC. At the time, most astronomers were keen to have their research grants administered by the same organisation that ran the facilities. I thought it made more sense to have research scientists all on the same footing when it came to funding and in any case thought there were too many absurd divisions between, say, general relativity (EPSRC) and relativistic astrophysics (PPARC), so I was among the (relatively few) dissenting voices at the time.

There were other reasons for my unease. One was that, during a previously funding squeeze, PPARC had taken money from the grants line (the pot of money used for funding research groups) in order to balance the books, necessarily reducing the amount of science being done with its facilities. If STFC decided to do this it would probably cause even more pain, because grants would be an even smaller fraction of the budget in STFC than they were in PPARC. Those EPSRC physicists using CCLRC facilities seem to have managed pretty well so I didn’t really see the argument for astronomy and particle physics being inside STFC.

The other reason for me wanting to keep research grants out of STFC was that the (then) new Chief Executive of PPARC, Keith Mason, had made no secret of the disdain he felt towards university-based astronomy groups and had stated on a number of occasions his opinion that there were too many astronomers in the United Kingdom. There are two flaws with this argument. One is that astronomy is essential to the viability of many physics departments because of its appeal to potential students; without it, many departments will fold. The other problem is that Mason’s claim that the number of astronomers had grown by 40% in a few years was simply bogus.  This attitude convinced me that he in particular would need only the slightest excuse to divert funds away from astronomy into areas such as space exploration.

It all seems a very distant memory now, but six or years ago UK physics (including astronomy) was experiencing a time of relative plenty. The government had introduced a system whereby the research councils would fund research groups on the basis of the Full Economic Cost of the research, which meant more money coming into research groups that were successful at winning grants. The government increased funding for the councils to pay for this largesse and probably diminished the fear of another funding pinch. Astronomers and particle physicists also felt they would have more influence over future strategy in facility development by remaining within the same organisation. In the end what happened was that STFC not only kept the portfolio of astronomy and particle physics grants, but also acquired responsibility for nuclear physics from EPSRC.

But then, in 2007, just after STFC came into existence,  a major financial disaster broke: that year’s comprehensive spending review left the newly formed STFC with a huge gap in its finances. I don’t know why this happened but it was probably a combination of gross incompetence on behalf of the STFC Executive and deliberate action by persons higher up in the Civil Service. The subsequent behaviour of the Chief Executive of STFC led to a public dressing down by the House of Commons Select Committee and a complete loss of confidence in him by the scientific community. Miraculously, he survived, at least for a while. Unfortunately, so did the financial problems that are his legacy.

I don’t like to say I told you so, but that’s exactly what I am going to dp. Everything that happened was predictable given the initial conditions. You might argue that STFC wasn’t to know about the global economic downturn.As a matter of fact I’d agree. However, the deep cuts in the science budget we have seen have very little to do with that. They all stem from the period before the Credit Crunch even started. Although Prof. Mason was eventually replaced (in 20111), the problems inherent in STFC are far from solved.

The last Comprehensive Spending Review (2010) was less bad for STFC than some of us feared – with a level cash settlement which still holds. In real times the funds are now being eroded rather than being slashed further, but the situation remains very difficult because of past damage. I don’t think STFC  can afford to settle for flat cash at the next spending review. The new Supreme Leader  Chief Executive of STFC, John Womersley, said much the same thing at last night’s RAS dinner, in fact.

I know this preamble has been a bit long-winded, but I think it’s necessary to see the background to what I’m going to propose. These are the steps I think need to be taken to put UK physics back on track.

First, the powers that be have to realize that university researchers are not just the icing on the cake when it comes to science: they actually do most of the science. I think the new regime at STFC recognizes this, but I’m not sure the government does. Another problem is that  that the way scientists are supported in their research is a complete mess. It’s called the dual support system, because the research councils pay 80% of the cost of research grants and Higher Education Funding Councils (i.e. HEFCE in England) are meant to provide the other 20%. But in reality it is a bureaucratic nightmare that subjects researchers to endless form-filling and costs hundreds of millions in wasteful duplication. This was true enough of the old Research Assessment Exercise, but has been taken to even higher levels of absurdity by the forthcoming Research Excellence Framework, the decisions coming out of which will be more influencing by guesswork and institutional game-playing than actual research excellence.

The Research Councils already have well-managed systems to judge the quality of research grant applications, so do we really needed the REF on top of them?  The second article I referred to in the introduction, on a study showing that Research Council grant income, appeared in last week’s Times Higher. That study shows -at least at institutional level – that the two streams are pretty closely correlated. While REF/RAE income is awarded on a retrospective basis, and grant awards are based on proposals of future activity, it should be a surprise that people with a good track-record are also good at thinking up interesting new projects. Moreover, panels such as the STFC Astronomy Grant Panel (of which I am a member) certainly take into account the applicants’ track-record when assessing the viability of research proposals.

So if we don’t need two systems, what could we have instead? Moving grants from STFC to EPSRC, as some proposed in the past,  would go part of the way, but EPSRC has many problems too. I would therefore prefer to see a new organisation, specifically intended to fund blue-skies scientific research in universities. This organisation would have a mission statement that  makes its remit clear, and it would take over grants, studentships and fellowships from STFC, EPSRC and possibly some of the other research councils, such as NERC.  The new outfit would need a suitable acronym, but I can’t think of a good one at the moment. Answers on a postcard.

As a further suggestion,  I think there’s a strong case to be made that HEFCE should be deprived of its responsibility for research funding. The apparatus of research assessment it uses is obviously  flawed, but why is it needed anyway? If the government believes that research is essential to universities, its policy on selectivity doesn’t make any sense. On the other hand, if it believes that university departments don’t need to be research groups then why shouldn’t the research funding element be administered by a reserch organisation? Even better, a new University Research Council along the lines I have suggested  could fund research at 100% of the Full Economic Cost instead of only 80%. The substantial cash saved by scrapping the REF should be pumped into grants to be administered by the new organisation, reversing the  cuts imposed we’ve endured over past years.

So what should  STFC become after the Triennial Review? Clearly there is still a role for an organisation to manage large experimental facilities. However, the fact that the UK now has its own Space Agency means that some activity has already been taken out of the STFC remit.  The CERN and ESO subscriptions could continue to be managed by STFC along with other facilities, and it could in some cases commission projects in university research groups or industrial labs as it does now. Astronomers and particle physicists would continue to sit on its Board.  However, its status would change radically, in that it would become an organisation whose job is to manage facilities, not research. The tail will no longer be wagging the dog.

I very much doubt if these suggestions are at all in line with current political “thinking” nor with those of many of my colleagues. The input to the Triennial Review from the Institute of Physics, for example, is basically that nothing should change. However, I think that’s largely because most of us working in STFC area,  have much greater confidence in the current management than we did in the previous regime rather than because the structure is right. Some of the bureaucrats in the Treasury, RCUK and HEFCE won’t like my suggestion  either, because they’ll all have to go and do something more useful.  But unless someone stands up for the university sector and does something to safeguard future funding then the ongoing decline in funding levels will never be reversed.

I very much doubt if many of my fellow physicists or astronomers agree with my suggestion either. Not to worry. I’m used to being in a minority of one. However, even if this is the case I hope this somewhat lengthy post will at least get you thinking. As always, I’d be interested in comments..

Authentic Tidings of Invisible Things

Posted in Poetry, The Universe and Stuff with tags , , , , on January 5, 2013 by telescoper

One of my very first blog posts (from way back in 2008) was inspired by an old book of poems by William Wordsworth that I’ve had since I was a child. I was reading it again this evening and came across this short excerpt, near the end of the book, from The Excursion, and entitled for the purposes of the book The Universe a Shell. It struck me as having a message for anyone who works on the science of things either too big or too small to be sensed directly on a human scale, so I thought I’d post it.

I decided to scan it in rather than copy it from elsewhere on the net, as I really love the look of that old faded  typeface on the yellowing paper, even if it is a bit wonky because it went over two pages. I’ve been fond of Wordsworth for as long as I can remember and, like a few other things, that’s something I’ll never feel the need to apologize for…

Shell-a

Shell-b

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.

Michael Schmitt's avatarCollider 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…

View original post 1,086 more words

Particle physics volunteers to be fleeced….

Posted in Open Access with tags , , , , on September 26, 2012 by telescoper

I heard the news yesterday that a body called the Sponsoring Consortium for Open Access Publishing in Particle Physics (SCOAP3) has arranged a deal whereby virtually all articles in particle physics will be available for free on journal websites. The deal will mean that authors will not have to pay thousands of dollars up-front in “article processing charges” in order to have their work available via Open Access media.

So far so good, you’re probably thinking. But read a little bit more about it and it becomes absolutely clear that SCOAP3 has walked straight into a trap laid by the academic publishers with whom it brokered the agreement. The principal deterrent to authors publishing via the “Gold” Open Access model has been that they would have to pay up-front fees, potentially around $2000 for each paper. Any sensible researcher would rather spend $2000 supporting their research than lining the profits of greedy publishers, so would probably opt for a “green” mode instead. Indeed many particle physicists already do this, putting their work on the arxiv where it is available for free anyway.

The publishing industry realises that most authors would simply bypass it and go for self-publication if they could, so it is naturally very keen on deals like this. What actually happens in the SCOAP3 agreement is that an author’s institution pays fees directly to the publisher. According to Nature News:

The consortium will pay the contracts from an annual budget of €10 million, which is funded not by authors or research grants, but by pledges from more than a thousand libraries, funding agencies and research consortia across the world. In effect, existing journal subscription fees are being repurposed to provide the open-access funds.

And there’s the rub. “Existing journal subscription fees” are already extortionately high, and out of all proportion to the actual cost of disseminating scientific knowledge. Authors may think that they’re not paying for Open Access under the new agreement, but in fact they are. It’s just a bit less direct. Their grants will continue to be top-sliced to pay for the SCOAP3 arrangement and, since science budgets are unlikely to rise for the foreseeable future, that means the cash available for actually doing research will fall. This agreement is very good for the publishers, but very bad for science.

The average cost for Open Access publication in Physics Review D. under the new scheme will be $1900 per paper. Ouch! And how does the publisher justify this cost? “To maintain revenue levels…”. I rest my case.

More of the  is going to happen in the UK, where £10M is being set aside from existing Research Council budgets, nominally to “pay for the transition to Open Access” but actually in order to maintain profit levels at the big academic publishing houses. Much of that £10M will no doubt disappear in deals like the one brokered by SCOAP3.  And that means continuing high profits for the publishers at the expense of falling levels of research funding. The whole thing stinks.

And if as an author you decide that you have a moral objection to being scammed in this way, under the SCOAP3 agreement you now have no way out. Even if you bypass the arrangement and just publish on the arXiv, the publishers will get their money directly anyway. You have to admit it’s a clever sting, but I’m still surprised the particle physics community has fallen for it.

This development convinced me even more that the research community has to take matters into its own hands, and organize its own publication strategy. Traditional journals are already virtually redundant and I confidently predict they will die a natural death in just a few years, but while they linger on their publishers will continue to fleece the academic community as long as they can. The sooner we put a stop to it the better.

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.

Student Comments

Posted in Biographical, Education, The Universe and Stuff with tags , , , , , on July 14, 2012 by telescoper

I sneaked into the department this morning to pick up some things from the office and leave some other things that I’ve finished with. I went quite early, to avoid the Saturday crowds there and back.

One of the things I found in my pigeonhole was a packet of student questionnaires about the third-year module Nuclear and Particle Physics for which I was responsible. It seems like a decade since I finished teaching it and marked the exams, but it can only be a couple of months. I was dreading reading the responses this time because I know I struggled a bit with this module, partly because it’s the first time I taught the Nuclear Physics part and partly for other reasons I won’t go into.

In fact the students were very kind and gave me quite good reviews; the only score that let me down really was that they thought the material was rather difficult. I’m not really surprised by that, because I think it is. However, as I’ve said before, I don’t think it’s a physics lecturer’s job to pretend that the subject  is easy; it is  a lecturer’s job to try to convince students that they can do things that are difficult. I don’t mean making  things difficult just for the sake of it, but trying to get the message across that a brain is made for thinking with and figuring difficult things out can be intensely rewarding.

The main criticism that students wrote in the space provided for their own comments was that they didn’t like the fact that I used powerpoint for some lectures. Actually, I don’t like using powerpoint for lectures either, but unfortunately I had no choice on some occasions. First I had a rather large class (85 students) and one of the rooms I had to use had a very small whiteboard; I was worried about its visibility from the back and the need to keep cleaning it every five minutes. Also in that room the projector screen covers the same area as the whiteboard, so it’s a pain to keep changing between powerpoint and whiteboard. Anyway, it’s a fair criticism. I’ll try to work out a better way of doing it next year.

To be perfectly honest I don’t like whiteboards much either. Call me old-fashioned, but  chalkboards are much better. Received wisdom, however, is that we have to have whiteboards, with all the ludicrous cost and environmental unfriendliness of the accompanying dry-wipe marker pens. But I digress.

Anyway, next Wednesday afternoon will see our graduation ceremony. Graduation day always reminds me of something somebody told me years ago when I attended my first one, at Queen Mary (and Westfield College, as it was then).  The essence of the comment was that what you have to remember as a lecturer is that when the students do well it’s their achievement; but when they don’t it’s your fault. Life’s like that, it’s never as symmetrical as particle physics.

Many of the students who took  Nuclear and Particle Physics will be graduating on Wednesday. I’m distraught that I won’t be able to go myself; this will be the first ceremony I’ve missed since I moved here five years ago.  If any of the graduating Physics class from Cardiff University happens to read this, I really hope you have a great day on Wednesday. I wish I could be there to shake your hand and wish you a very fond goodbye, but sadly that’s just not possible on this occasion.

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…