Another LHC Update

June 9, 2011

For the past 11 days the Large Hadron Collider has been running with a 1092 bunch filling scheme adding 325/pb to the total data delivered. Based on an average peak luminosity of 1.13/nb/s this gives a Hübner Factor of 0.3 which is very respectable for this early stage of the run.

During this time the beams have been dumped frequently by problems such as software errors that are being rapidly fixed. UFOs have been another major headache. These are thought to be dust particles that fall into the beam. There is so far no sign of their numbers dropping as the beam zaps them up, but the dump thresholds can be changed in the worst hit areas to reduce the number of UFOs that cause a run to be aborted. This means that overall the run efficiency should improve and the expectation should be for a somewhat better Hübner Factor once they settle into the longer run.

The first successful fill with 144 bunch injection ran last night. The longer train length means a few more bunches can be fitted into the ring. They just need two long fills with this filling scheme before they can step up to 1226 bunches in each beam, so higher luminosities should be with us soon.

The schedule for the rest of the year has been modified to replace the four planned maintenance breaks with just three breaks, but slightly longer in duration. The immediate effect is that the next stop moves back from 16th June to 29th June, allowing more data to be collected in time for the big HEP-EPS conference at the end of July.

This week it has been the Physics at LHC conference in Perugia that has been grabbing most attention. There have already been some new limits shown, such as seen on these plots from a talk today on ATLAS top physics by Marina Cobal.

The talks on the final day tomorrow are the ones most likely to declare any new observations rather than just exclusions using the 240/pb on offer. Indications from conference notes already released suggest that we should not expect too much. A lot of the talks have not explored beyond the 40/pb dataset from 2010.

A pessimist would say that they have concentrated on the best-hope channels for presentations at this conference so the absence of new observations beyond the standard model here means that nothing new is showing up yet. An optimist, however, might say that they have only been able to approve the less interesting searches in the time available. All the best results may be in the places where no new data was shown this week because they will want to wait a little longer for more data to get conclusive results. We wont have long to wait until the EPS-HEP conference where 1000/pb of data should be on the table.

Meanwhile the main buzz is about the CDF bump at 150 GeV. Tomorrow there should be a seminar at Fermilab from the D0 group to tell us whether or not they also see the bump. It will be webcast here. Another version of the talk will be seen at PLHC on Saturday. Woit has already passed on a rumour that says the answer will be negative. Even if he is right, this will leave open the question of how the bump seen by CDF can be explained. The results should be consistent so the two groups will need to compare their analysis methods to find out what went wrong.

Update 9-Jun-2011: I have checked all of the talks at PLHC 2011. There are 10 talks from ATLAS and one from CMS where new searches using 2011 data up to 236/pb are presented. They all correspond to notes already published last week so we know that only new exclusions limits are found. No new physics is forthcoming this week from the LHC, unless they slip in an extra last minute talk.


Don’t Say I Didn’t Warn You

June 8, 2011

Just so you have some advanced warning of predictable events that are likely to feature on this blog, I have added a Science Calendar at the bottom of the right hand column. Suggestions for additions are welcome, but may be ignored.


Best science blog post?

June 7, 2011

viXra Log is nominated for best science blog post at 3QuarksDaily. Voting end tomorrow.

Update: Currently in about 28th position, needing to be in top 20 to make final round.

Update: We didn’t quite make the cut but thanks for all the votes, I think we were about 28th position out of 70


Shaw Prizes for Enrico Costa, Gerald Fishman, Jules Hoffmann, Ruslan Medzhitov, Bruce Beutler, Demetrios Christodoulou and Richard Hamilton

June 7, 2011

Today seven scientists are up to $500,000 minus tax richer for having won this years Shaw Prizes.

Astronomy

First up are Enrico Costa and Gerald J Fishman for leading the NASA mission that resolved the origin of gamma ray bursts. It does not seem to many years ago since gamma-ray bursts were regarded as one of the great unsolved mysteries of science. They had first been detected in 1967 by the Vela satellites which had been placed in orbit by the US military to check that the USSR was not detonating nuclear weapons in contravention of the 1963 partial test ban treaty. Nuclear explosions would send gamma rays into space where the satellites would detect them. Instead they observed gamma ray bursts coming from space.

From 1973 when their existence was declassified until 1997, these events were so mysterious that astronomers could not even tell if they came from nearby in our galaxy or billions of years away across the universe. NASA launched the BeppoSAX satellite to try to resolve the question, In 1997 it observed a powerful gamma ray burst which left an afterglow long enough for Earth based telescopes to lock onto its location just 8 hours later. Now they could see that it came from a very distant galaxy.

The gamma rays are so bright at that distance that it is inconceivable that they are being radiated equally in all directions in such a short space of time. The amount of energy that would have to be concentrated into a small volume is juts not possible. It is thought that they come from energetic supernovae with a rapidly rotating remnant that focuses the gamma rays into a tight beam. we only see the burst for the small fraction of events where we happen to lie in the direction of the ray.

Life Science and Medicine

Next were Jules A Hoffmann, Ruslan M Medzhitov and Bruce Beutler for uncovering the biological mechanisms for innate immunity. When an animal or plant is infected it deploys a number of mechanisms to defend itself. One of the first is the innate immune system, thought to be one of the earliest mechanisms to evolve because it is so widespread across diverse forms of life. In plants it remains the dominant immune system, but advanced animals have developed more effective systems of adaptive immunity that can change to attack specific viruses or other contagents.

Understanding all forms of immunity is vital to medicine because it provides the knowledge needed to find drugs that help us fight diseases.

Mathematics

Finally, Demetrios Christodoulou and Richard S Hamilton won the mathematics prize for work on differential manifolds with implications for general relativity and the Poincaré conjecture.

When Grigori Perelman famously turned down the Fields medal and the million dollar Clay prize for resolving the Poincaré conjecture, he said that his reason was that other mathematicians such as Richard Hamilton has contributed just as much to the proof. He need not have been so concerned since Hamilton has now himself been recognized with a lucrative award.

It was Hamilton who discovered the theory of Ricci flow on differential manifolds that lead Perelman to his proof of the Thurston geometrization conjecture that was known to imply the truth of the Poincaré conjecture, a mathematical problem that had remained unsolved for a hundred years.

Demetrios Christodoulou is a mathematical physicist who worked for his doctorate at Princeton under the direction of John Wheeler. He is known for his extraordinarily difficult proof of the unsurprising fact that flat empty Minkowski space is stable under the action of nonlinear gravitational dynamics as described by general relativity.


New Particle Physics, on the way?

June 7, 2011

The PHLC2011 conference is underway with the promise of new reports from CMS and ATLAS using around 200/pb of data. The conference notes released by ATLAS so far suggest that only better exclusion limits will be found unless they are holding back some surprises. Today CMS have also shown their first paper using 190/pb from 2011 data. It also provides new exclusions.

From before the conference the main excitement came from the Tevatron where CDF have shown a 4-sigma bump at 150 GeV in decays producing W bosons and two jets. Dorigo remains firmly sceptical while Jester reports that detailed analysis of the events are consistent with a new particle just below 300 GeV that decays into a W-boson and the lighter unknown particle at 150 GeV. A study by D0 using similar data will be a crucial indicator of whether this effect is here to stay. They are expected to report on Friday at Fermilab.

Before then we will have a number of new search reports at PLHC2011, mostly on Thursday and Friday, but also today we have a special seminar from Jon Butterworth on behalf of ATLAS that just might have news (Update: It doesn’t).

So by the end of the week particle physics could look very different, and if it is all an anti-climax we just have to wait for the next big conference EPS-HEP2011 where at least 1000/pb of LHC data will be on show at the end of July. My betting is that will be the one to watch out for.


Is the Universe Digital or Analog? the results

June 6, 2011

The FQXi essay contest results are out, and I am very proud of my fourth prize place. Thanks to all of you who voted for me in the community round.

The winner is Finnish Lecturer Jarmo Makela with his story based on an imagined encounter with Isaac Newton which looks at the discreteness of black holes.

Wel done to all the other prize winners too.

 


Rebooting the Cosmos

June 5, 2011

Over the last few days the World Science Festival has been running in New York and has featured some very interesting discussions amongst scientists on a variety of  popular science subjects such as the mutiverse and the search for life in space. I have been following it because it had been said that the results of the FQXi essay contest (Is Reality Digital or Analog) would be announced at the festival and I am interested to see which authors are going to beat me to all the juicy prizes. So far nothing seems to have been mentioned about that but last night there was an interesting discussion broadcast live with the title “Rebooting the Cosmos: Is the Universe the Ultimate Computer?” It could have been inspired by the essay contest.   Two of the four scientists (Ed Fredkin and Seth Lloyd) were cited in my essay for the contest and another (Fotini  Markopoulou) was cited in my earlier FQXi essay on the nature if time. The final member of the panel was computer scientist Jürgen Schmidhuber. So this was a discussion of great interest to me and I was not disappointed by it.


The main question up for discussion was, “Is the universe a giant computer?” There is an argument that says that in the future we will build computers so powerful that we will be able to simulate universes in great detail. Assuming that life continues for a long time and that a few people are interested in playing such games, there will be vast numbers of such simulations. In fact, within the multiverse there will be so many simulations going on inside computers that they will vastly outnumber all the “real” universes. The conclusion is that we are infinitely more likely to be in a simulation ourselves than in a “real” universe. Actually we really have to conclude that there are no real universes, just simulations within other simulations.

I don’t take this argument too seriously, but a growing number of physicists are taken by such ideas and it is at least worth thinking about on a philosophical level. Does this mean that we are vulnerable to the possibility that the being running our particular simulation might decide to pull the plug at any time and we would just cease to exist? Some people seem to think so! I take the view that if there is one simulation running that matches our universe then there must also be infinitely many of them, by the same argument. We have no way to distinguish which one we are in because we have no access to the outside “other” world as Ed Fredkin calls it. So what we should experience is the combined effect of all the simulations that matches ours at any given place and time. In that case it is safe to assume that the simulation will go on in most cases so we are in no real danger of being stopped, phew.

Although these ideas seem wacky and untestable, I think they are worth thinking about because they can give us some clues about how the universe could work is we accept that such possibilities can make sense. This is how the role of philosophy in physics should work. The broad concepts may not be scientifically falsifiable themselves but they can lead eventually to other ideas that are. Everyone understands this, right? I think it is not unreasonable to say that the universe runs like a quantum computer, rather than it is a quantum computer. This may become more apparent in the fundamental laws of physics when we come to understand them better.

As an independent physicist who sits at home linked into the internet I don’t get to meet real physicists very often. However, it happens that I have had the good fortune to meet Ed Fredkin and exchange some ideas with him. I even have a little anecdote so I am going to finish of with that. Fredkin is remarkably accomplished in a number of fields. He was an airforce pilot who became a professor of computer science at MIT despite a lack of academic background. As an architect of some of the early PDP computer systems he quietly invented a number of concept in operator systems that form the basis of all computers today. he also invented several technologies such as a desalination process that earned him considerable wealth. His interest in applying digital ideas to physics have also been very influential especially through his contact with Feynman, ‘t Hooft and others. You can hear about some of that in the program.

A few years ago I got to know Fredkin because of his interest in some things I wrote in my online book about “Event-Symmetric Space-Time”  the last time I met him was in Antibes where he keeps his yacht and we discussed his work on cellular automata. It is in a picturesque bay where they are used to celebrities passing through. One evening we were is a restaurant and he was telling me about his role in the  Sakharov affair, another unrecorded episode of his amazing life story. As we talked I noticed over his shoulder that the waiter who had served us was looking towards us curiously. Fredkin turned round and caught his eye, then he turned back to me and said “oh dear, I know what is going to happen next” Sure enough the waiter came back over to our table and spoke nervously. “Excuse me, but could I have your autograph?” he asked. “Of course” said Fredkin, “but who do you think I am?”, The waiter paused looking a little confused, then burst out, “Sir. I recognized you immediately. You are Steven Spielberg!”


ATLAS squark and gluino search with 165/pb extends SUSY exclusions

June 4, 2011

A new conference note from ATLAS using 165/pb of data has extended exclusions for SUSY. Previous published results used 36/pb of 2010 data. These new findings will be reported at the Physics at LHC conference next week. With 691/pb delivered, further search results will be possible very soon.

Gluino masses below 725 GeV are excluded in the simplest models. The new limit of the excluded region is the thick red line on this plot. The odler limit using just the 2010 data is the thinner black line. The no-go zone has extended about 200 GeV to the right.

It is disappointing for many phenomenologists that no SUSY signal has yet appeared, but SUSY has a large parameter space and it will take much more data to really rule out the theory completely. It seems likely that if SUSY is not found then something else will prove to be the solution for physics at the TeV scale. The data from the LHC to be accumulated over the next two years will tell us how the Higgs sector looks. Whether it is SUSY or not, it is likely to be something of interest.


ATLAS publish searches with 205/pb

June 2, 2011

Up to this point most publications from the LHC experiments have been based on the 2010 data of up to 43/pb. Today ATLAS have published their most advanced results yet in two conference notes using 163/pb of 2011 data and 42/pb of 2010 data for a total of 205/pb. The first note looks at the Dijet Mass distribution using just the 2011 data, and the second looks for one muon and missing transverse momentum with 205/pb. No results inconsistent with the standard model are seen but these papers are significant as a sign that we can expect to see a lot more publications from these amounts of data shortly.

The 163/pb of data for 2011 was collected around the 26th of April so the analysis has taken about five weeks. The total recorded data in each of ATLAS and CMS is now around 600/pb

Update 3-Jun-2011: There is now a third conference note on a search for dilepton resonances using up to 236/pb

Update 4-Jun-2011: A fourth note reporting a search for squarks and gluinos using 165/pb is now online.


2011 Gruber Prize for Cosmology

June 2, 2011

The 2011 Gruber Cosmolgy Prize has been awarded to Marc Davis, George Efstathiou, Carlos Frenk and Simon White for pioneering numerical simulations of galactic structure formation that provides strong evidence for the Cold Dark Matter theory.

The prize of $500,000 will be shared among the recipients.

This award was a good call because of all the remarkable developments in cosmology over recent years, this one has been one of the least recognised. Congratulations to all.

The prize is awarded by the Peter and Patricia Gruber Foundation which also sponsored this years FQXi essay contest, the results of which are due to be announced at the World Science Festival in New York any day now (if the judges have reached a conclusion in time). The festival which has already started has a strong web presence with live broadcasts for those who can not make it in person.


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