John Ellis

From Big Bangs to Little Bangs

A PPARC Council meeting yesterday took me to London just as the multiple terrorist explosions were unfolding. I arrived by train at King’s Cross station shortly after the explosion in an Underground train in a tunnel nearby. We were told the station and all the Underground system were closed down, so passengers flowed out on the street wondering how to get to work or, in my case, how to get to my meeting over by the Houses of Parliament. No free taxis, of course, and the buses were crammed tight. Anyway, my instinct was to keep away from places with many people, so I started walking.

After a couple of hundred metres, I heard the boom of a new explosion. It turned out later that this one was on a bus a couple of blocks away. I wonder how many people had got on that bus because the Underground was no longer operating?

Central London was full of pedestrians, few buses as they were also being withdrawn from service, and not much other traffic apart from bicycles and the full taxis. Shortly after we had started the PPARC meeting at the Royal Academy of Engineering, the building custodians came in and told us to open the windows, so as to provide a path for the blast wave from any explosion without breaking the windows (the nearby Houses of Parliament being a potential target), and to pull down the blinds.

With gallows humour, the meeting continued. Ironically, at our places around the table were provided images of the Deep Impact probe’s recent collision with the comet Tempel 1. I found myself wondering whether this was legitimate scientific research or cosmic vandalism. (See the cartoon: I apologize for not acknowledging the copyright properly!) I guess the principle is not so different from particle physics colliders: you bang particles together and use detectors to examine what comes out. But we should perhaps treat comets with more respect: one of them may have Earth’s number on it. At least particles cannot destroy the planet.

Following the meeting, my concern was whether I would be able to get back to Cambridge, where I was staying and my son was spending the day looking around Colleges. After taking a hotel room in London, where I was able to watch the news on TV and freshen up with a shower, the BBC announced that local trains out of King’s Cross station had restarted, so I walked over there in the pouring rain and eventually made my way back to Cambridge for late-night dinner with my son in a Turkish restaurant.

Back in the (ex-)USSR

Back to Russia again, for the second time in a week, this time for a meeting of Scientific Council of the Joint Institute for Nuclear Research (JINR) in Dubna. A new Director has recently been designated, Alexei Sissakian, and the laboratory is defining a road map for its scientific programme during the next decade. The JINR will celebrate its 50th anniversary next year. It is a valued international partner with much technical expertise and many excellent physicists. Much of JINR’s scientific programme is in collaboration with other laboratories such as CERN as well as universities outside Russia.

The new management wants to prioritize these as well as Dubna’s internal programmes in particle, nuclear and condensed-matter physics, and start a new project of global interest, if possible.

The first picture shows Alexei Sissakian, Vladimir Kekelidze (the head of the JINR Laboratory for High-Energy Physics and currently spokesperson of the NA48 experiment at CERN), yours truly and Mikhail Itkis catching up during the conference dinner.

Most of the former Soviet Union and Eastern European countries are members of the JINR. The laboratory went through hard times in the 1990s. JINR member states are now paying a larger fraction of their promised contributions, but salaries are still very low and JINR staff cannot afford to retire on their even lower pensions. We heard a lot at this meeting about the possibilities for collaboration with Germany, which (as the former east Germany) used to be a member state of the JINR before the fall of the Berlin wall, and currently has a special cooperation agreement with Dubna.

Dubna is set on the Volga River. Walking along its embankment, you come across middle-aged joggers and sunbathers, teenagers sweeping desultorily with newly-made birch brooms, ladies planting flowers in recently-raked beds, and people tending their allotments or sailing on the river. During the Soviet era, it was a scientific idyll, but adapting to the priorities of the new Russia and its former associates is an uphill struggle.

From (India and) Russia with love

This week we had contacts with high-level representatives of a couple of non-member countries that are participating strongly in the LHC programme. Last Wednesday CERN was visited by the President of India, Avul Pakir Jainulabdeen Abdul Kalam. Born into a modest fishing family, he studied science, then became a rocket engineer and the father of the Indian missile and satellite programmes. He met Indian teams working at CERN to test LHC magnets and on Grid software, as well as the usual CERN bigwigs. He is the first head of state I have met who knows about the Standard Model of elementary particles! The first picture shows yours truly with (from right to left) Archana Sharma, an Indian staff member of CERN, Diether Blechschmidt who has been handling India-CERN relations, Anil Kakodkar, the head of the Indian Department of Atomic Energy and several Indians working at CERN on the LHC project.

The next morning, I was off to Moscow as a member of  a CERN delegation for one of our regular six-monthly coordination meetings with the Russian Minister of Education and Science, A. Fursenko. From our hotel, we had a good view of the Kremlin (left), St Basil's church (right) and an exhibition of construction equipment (foreground). The third picture was sent to me by my good colleague Vladimir Kadyshevsky, the Director of the Dubna Laboratory, with the heading 'From Russia with love'. Over the Minister's head (at the left) you see the CERN delegation, with our Director-General Robert Aymar in full flow. Several Russian Institutes, notably the Budker Institute of Nuclear Physics in Novosibirsk, are participating in the construction of the LHC accelerator as well as its detectors. Progress is generally good: for example, Novosibirsk has provided the magnets for the lines that will transfer protons between CERN’s existing SPS accelerator and the LHC. For years, several magnets were arriving by truck every month from central Siberia. After their installation, these magnets worked perfectly the first time a beam was sent through them along the transfer line to the LHC tunnel.

This CERN-Russia meeting provided the opportunity for a bit of tourism and a convivial dinner with our Russian partners, as seen in the last picture. That's Minister Fursenko sitting on my right: do not be misled by the impressive array of bottles of mineral water in the foreground!

Was there a sneutrino in your past?

Where does the matter in the Universe come from? We are made of molecules containing atoms of heavy elements made in supernova explosions. Atoms could not exist when the Universe was less than about 300,000 years old. Before then the Universe contained mainly photons and neutrinos, with some electrons, protons and ionized nuclei of light elements such as Helium and Lithium. These were made out of protons and neutrons by nuclear fusion reactions when the Universe was about a minute old. The protons and neutrons were themselves assembled out of quarks when the Universe was a few microseconds old. But where did the quarks come from?

Andrei Sakharov showed in 1967 how these quarks could be manufactured if the elementary particle interactions distinguished between matter and antimatter, as seen in the laboratory, could change the net numbers of quarks, as expected in many theories but never seen in the laboratory, and if thermal equilibrium broke down in the very early Universe. Ever since, particle theorists have been constructing models how this Sakharov mechanism might have worked, when the Universe was anywhere between 0.000000000001 and 0.000000000000000000000000000000000001 seconds old. The Standard Model of particle physics could not have done the job, so many speculative extensions of it have been proposed.

To my mind, one of the most plausible extensions of the Standard Model is supersymmetry (just look at the subjects of my research papers!), so could the minimal supersymmetric extension of the Standard Model have created the matter in the Universe? Sin Kyu Kang and I wrote a paper last week: http://arxiv.org/abs/hep-ph/0505162 proposing that the decays of the supersymmetric partners of neutrinos, ‘sneutrinos’, might have done the job, relatively late in the history of the Universe when it already had the ripe old age of 0.000000000001 seconds. Previously there had been plenty of ideas how the decays of neutrinos or sneutrinos might have produced matter much earlier in the history of the Universe, starting with pioneering work of Fukugita and Yanagida in 1986, but we wanted to do it as late as possible so as to offer a chance of testing the idea in the laboratory. Only time will tell whether this idea could have worked, but it does seems possible that there was a sneutrino our past!

Sur-Prize

As I have mentioned in previous posts in this blog, my collaborators Nick Mavromatos, Dimitri Nanopoulos and I have been developing a novel string approach to cosmology, in which we allow the string to live in a space that evolves with time. One of the interesting features of this approach is that it offers a possible mechanism for the acceleration in the expansion of the Universe that has been discovered in the last few years. In our time-dependent string approach, as we showed back in December, the expansion of the Universe MUST accelerate eventually, at a rate related to the string coupling, which is asymptotically free, a bit like the strong interactions. The decrease with energy of the strong coupling has been observed in many experiments, and there have been probes of the rate of change of  other coupling ‘constants’, but the rate of change of the string coupling predicted by our idea seems out of reach.

Well, a couple of months ago we entered a description of this idea in an annual essay competition organized by the Gravity Research Foundation: see http://arxiv.org/abs/gr-qc/0503120. For more information about this essay competition and a list of past winners, see:http://libserv.aip.org:81/ipac20/ipac.jsp?uri=full=3100001~!5171~!0&profile=icos#focus. We did not really expect to win this time, because our idea is rather speculative and we had already won the First Award with a previous essay a few years ago. However, to our surprise, the Foundation liked our essay and gave us the first award again.

Who said that gravity never strikes twice in the same place?

The universal language of astroparticle physics

One of the most fascinating aspects of particle physics is its close connection with astrophysics and cosmology. In particular, many of the fundamental questions about our Universe - such as the origin of matter, the formation of structures including galaxies, stars and eventually ourselves, the great size and age of the Universe – can only be answered in the universal language of particle physics. During the past week, I have been developing these connections in several different places (and languages!).

The Swiss Institute for Particle Physics organized a meeting at the Integral satellite Science Data Centre (ISDC, see the first picture) to brainstorm ideas for possible new projects in astroparticle physics during the LHC era. Thierry Courvoisier, the head of the ISDC, gave an astrophysicist’s point of view - centred more on energetic objects in the present-day Universe such as gamma-ray bursters, active galactic nuclei, X-ray sources – and I presented a particle particle physicist’s point of view – centred more on the early Universe and the detection of dark matter via direct or indirect means. High-energy astrophysics and cosmology are both interesting, but they are not the same, and now it is up to the Swiss particle physicists to decide what they want to do!

The following day, I was off to the Physics Department of the University of Geneva, at the invitation of Alain Blondel, to give an evening lecture to the general public (in French) on ‘La Naissance de la Matière’ (see the second picture). (This talk compensated for a talk scheduled earlier which I was unable to give because I was grounded at Buenos Aires airport – see my post of March 19th.) The symbiosis between particle physics and cosmology is clearly a big draw for laypeople and prospective students, as well as intellectually fascinating in its own right.

Finally, yesterday I was off to the Accademia dei Lincei in Rome at the invitation of Milla Baldo-Ceolin (see the third picture) to give another public lecture (this time in Italian) on ‘La Nascita de la Materia’. This was almost a direct translation of the Geneva talk, and preparing it brought home to me how much Italian I had yet to learn, though my hosts were very polite! Founded 402 years ago, one of the Accademia’s first members was Galileo. It now meets in the venerable Palazzo Corsini in the popular Trastevere area of central Rome. This abounds in characteristic eateries: too bad that I had only enough time to sample one!

Moscow, Music and Mongols on the Mississipi

Next stop after College Station was the University of Minnesota in Minneapolis to visit my friend Keith Olive and work with him and Yudi Santoso – see the first picture. This was the first time I had meet Yudi, despite having co-authored 13 papers with him over the past 31/2 years! In addition to making good progress on our research projects, I also gave a seminar about the search for supersymmetry.

The Fine Theoretical Physics Institute at the University of Minnesota - whose campus straddles the Mississipi River, as seen in the second picture - is notable for the fact that 6 of its 7 faculty come from Russia. They include the former ITEP particle theory franchise, Misha Shifman, Arkady Vainshtein and Misha Voloshin. These guys are legendary for bearing down hard on seminar speakers who exhibit sloppy thinking. First tip of this posting: if you are giving a seminar at the University of Minnesota, get them to start arguing among themselves, and they may forget about the speaker!

The third picture is one I used as a background in the Powerpoint slides for my seminar. It was taken the previous evening at a concert the previous evening by the hot new hard-rock group Velvet Revolver, that Keith and I had attended the previous evening. Second tip: if you go to hear them, be sure to take ear-plugs!

And what about the Mongols? While in Minneapolis, I was reading an excellent book: 'Genghis Khan and the Making of the Modern World' by Jack Weatherford of Macalester College in Minnesota. Nothing to do with physics, but fascinating, nevertheless, and page-turningly well written! Do you know how violin strings, pasta, gunpowder and men's trousers came to Europe? Via the Mongol Empire, which was the first continent-wide economic free-trade area with complete religious tolerance. Final tip of this posting: read the book!

Quantum Gravity Phenomenology: nice hat, but where are the cattle?

Off to College Station, Texas for a small workshop on the possible phenomenology of quantum gravity hosted by the Mitchell Institute of Theoretical Physics at Texas A&M University. Bringing together advocates of string, loop gravity and the more traditional quantum gravity communities, there was much discussion of possible quantum decoherence effects induced by quantum gravity, limitations on clocks and computation, and the possibilities that either Lorentz invariance and/or the principle of equivalence might be violated as a result of quantum fluctuations in the fabric of space-time. Amusing speculations, but no experimental beef yet, just strengthening upper limits from laboratory experiments and astrophysical sources such as the Crab pulsar and gamma-ray bursters, see for example http://arxiv.org/abs/astro-ph/9712103.

A highlight of the workshop was a banquet dinner hosted by Chris Pope, one of the organizers, and prepared by Hong Lu – see the picture. The meeting also provided an opportunity to catch up on some research projects with Dimitri Nanopoulos and his students Joel Walker and Eric Mayes, which we hope will reach the research archive ere long.

Two weeks of peace and quiet

Sorry to have been quite for a while: I was too busy having a quiet time!

For two whole weeks, I did not budge from CERN, and so was able to catch up on a couple of projects. One of these was a fresh look at the constraint on supersymmetry imposed by the rare B_s to mu mu decay. The CDF and D0 experiments at Fermilab have been looking for this: no banana so far, but they have good prospects to improve significantly their sensitivity, and subsequently the CMS and ATLAS experiments should be able to push much further, and observe this decay at the level expected in the Standard Model. New physics accessible to the LHC, such as supersymmetry, might make B_s to mu mu decay less rare than in the Standard Model. Unfortunately, as Keith Olive, Vassilis Spanos and I pointed out in http://arxiv.org/abs/hep-ph/0504196, calculating the rate for B_s to mu mu decay is complicated by uncertainties in Standard Model parameters such as the masses of the top and bottom quarks, clouding the interpretation of this prospective constraint on supersymmetry.

I was also able to write up the talk I gave a few weeks ago in Kolkata on `From Little Bangs to the Big Bang', an introductory review of aspects of the connection between particle physics and cosmology that I hope you might find interesting: http://arxiv.org/abs/astro-ph/0504501.

Not travelling does not mean that I have been neglecting my other job looking after CERN's external relations! I met a delegation from Romania, participated in a diplomatic reception for ambassadors to international organizations in Geneva and gave an introductory presentation of CERN to a group of visitors from the UK. I also dealt with aspects of CERN's relations with Argentina, Chile, Cyprus, India and Ireland. I also worked to bring some undergraduate students from non-member countries to participate in our summer intern programme, and prepared an application to the European Union for a project to support PhD students to work for periods in the CERN Theoretical Physics Division.

I also spent some time thinking about CERN's possible future projects such as CLIC - for a recent progress report by Ian Wilson, see: http://clic-meeting.web.cern.ch/clic-meeting/, and attended an inspirational seminar by Peter McIntyre about high-field magnets and the possibility of tripling the LHC energy some day.

Oof! After all that, the following week of travel almost comes as a relief ....

Holes around the world

The late lamented SSC continues to provide grist for the literary mill -  I have just finished reading 'A Hole in Texas' by Herman Wouk, which I recommend as an entertaining page-turner. Its portrayal of a physicist's lifestyle is hardly typical - how many of us have jetted around the US on a private jet in the company of a nubile Congresswoman who was previously a movie star - but its Washington shenanigans are frequently hilarious. Also, you can amuse yourself trying to recognize some of the characters - the diminutive Director Emeritus of SLAC with a Germanic name is not very difficult to identify!

The SSC hole in the ground was abandoned, but this week I attended a workshop in the French Alps in Aussois, near Modane (see the first picture) about the physics one could do with a next-generation undergound detector, perhaps a megaton of water or a couple of hundred thousand tons of liquid Argon. Groups are proposing such experiments in Japan, the US and Europe, e.g., at Frejus which is also near Modane. I landed the job of giving the opening talk at the meeting, and emphasized that non-accelerator experiments such as these are potentially as important as collider experiments and non-collider accelerator experiments: http://nnn05.in2p3.fr/.

The two main physics topics on the agenda of such a large new experiment would be neutrino physics and continuing the search for proton decay. In addition to atmospheric neutrinos, such a detector could also look for astrophysical sources such as supernovae, either individual new explosions nearby in the Universe or the diffuse background from past explosions throughout the Universe, and also study the oscillations of neutrinos produced by accelerators, e.g., at CERN, as discussed in my previous blog entry. These neutrinos might be produced in the decays of low-energy pions (superbeams) or high-energy unstable nuclei (beta beams) or stored muons (neutrino factory). The hotel bar, which doubles as a discotheque, already has a 'superbeam', as seen in the second picture. Perhaps this is a good omen?

The first round of large underground water experiments, called IMB and Kamiokande, was motivated by the search for proton decay, but got famous instead because of their neutrino physics, particularly the observation of supernova 1987a and the discovery of neutrino oscillations. Perhaps the next round, even if their 'bread-and-butter' physics is neutrino physics, including the search for CP violation, might actually become famous because of some 'jam' provided by proton decay. This is still very much expected in grand unified theories, and could well be accessible to such a hole in the ground!