Cusco Saturday

Here was a cold blustery Saturday in the historic city of Cusco in Peru.
At 11,000 feet, the air is spare and bracing, but not for everyone. They 

keep oxygen at the airport and in every hotel,for those who need it 

(people do).The city is in the middle of a valley surrounded by 

mountains. As the plane comes down, the feeling of familiarity 

intensifies. The city looks and feels exactly like Bhutan, despite being

 on the other side of the world.


The streets are narrow and steep, and lined by cobblestones. You need to 

skip out to the high footpath each time an Alto goes by (Suzuki seems to 

have good sales here). If two cross each other, one has to squeeze itself 

flat against the kerb (yes, the streets are two way, but one Alto and one 

llama facing each other is what the two way can handle).The cathedral in 

the main square was rain drenched, but was still thronged with 

worshippers. The clouds and sunshine chased each other, around the little 

park in the middle, and the shops round the square (Inca silver, Inca 

pottery, Inca shawls, alpaca and llama woolens). The school children were

going home, the little girl had a big smile.


The hotel was old and full of antiques and atmosphere. There was a steep 

staircase and a courtyard full of plants, and a terrific view from the 

terrace. The drawing room had a fire-place, the internet and coca leaf tea. 

The staff was truly sweet.  What more could one ask for? It was too short a

trip, one could ask to go again,if Pacha Mama so wills! 

This blog post is by Neelima Gupte and Sumathi Rao. 

Photos by and by. 

Dark Matter

This topic is a bit late, but is too important to be left out altogether.The  Alpha Magnetic Spectrometer experiment in the International  space station has seen the excess of positrons at high energies that is supposed to be one of the characteristic signatures of dark matter. Dark matter is supposed to neither emit nor absorb light. Its presence is inferred from its gravitational effects on normal matter. Dark matter is supposed to account for about  85 percent of the total matter in  the universe. The current experiments carried out by the AMS experiment measured the excess of high energy positrons in earth bound cosmic rays, as predicted due to the presence of dark matter.

Well, dark matter is supposed to be made up of some hitherto undetected types of elementary particles, e.g. weakly-interacting massive particles, or WIMP-s, as well as many others. Particles of this type would be produced thermally in the early universe and are predicted by many theoretical extensions to the Standard Model of particle physics. If dark matter is made from such particles, and they encounter their own antiparticle, they may annihilate each other and produce some of the particles we are familiar with, e.g. protons and electrons. Some possible dark matter particles, are expected to be their own antiparticles, (e.g. photons, Z particles and Higgs bosons are examples of particles which are their own antiparticles), they are also expected to be rather heavy. If such dark matter particles encounter each other and annihilate to give lighter weight familiar particles, then these light particles would have high energy. This is a consequence of energy momentum conservation, by which pairs of heavy, slow moving dark matter particles would convert their energy into pairs of light, fast moving, familiar particles, as seen in cosmic rays, which the AMS measures. What the AMS does, is to count the number of electrons and positrons at a certain energy, and measure the fraction of positrons. At high energies, in the absence of dark matter annihilation, the number of electrons is expected to be much larger than the number of positrons. This is because, electrons are common in the universe, and can be easily accelerated to high energies, whereas positrons are produced out of collision processes of electrons, and consequently come out with lower energies than those of the electrons that produced them. However, if the electrons and positrons came out of dark matter particle annihilations, they would be equally energetic. In this case, the fraction of positrons would increase at large energies. The  typical energy of such electron positron pairs would be a little less than  the mass energy of the annihilating dark matter particles, and hence there would be a bump in the energy distribution of the positrons at this energy.

Experts say that the AMS result only confirms what other experiments, like, the measurements made by the Pamela and Fermi satellites, as well as terrestrial experiments. However, it is all to the good that all the experiments are pointing in the same direction. The AMS also has far more accurate measurements, and has narrowed the error bars. The AMS also finds that the distribution of positrons is isotropic, which was not quite expected from astronomical sources. All said and done, there are exciting days ahead in this direction. As for dark energy, may be some other day.

This blog post is by Neelima Gupte and Sumathi Rao.

For a more technical description of dark matter, and all the other experiments, see  this blog.


Tailpiece:

Two positrons walked into a bar.  `I'm much higher than you on the GeV scale' , bragged the high energy positron.  `And how did you do it' said the low energy positron, wistfully.  `By dark and annihilatory deeds', said the  high energy positron.

Land of Kings 2

Last month saw another excursion to Rajasthan, this time to Jaipur. Jaipur, of course, is a big city, the capital of Rajasthan, but it still manages to retain some of the appeal that small towns have, especially in the outskirts. The skyline is lowlying, the roads are wide, and there is a sense of space on the edge of the desert.

This was a work visit, to the LNMIIT (now headed by an old colleague from IIT Madras), which is blessed with a very well developed campus, and impressive architecture, especially that of the main building, which is inspired by the Jantar Mantar, and picks up the local flavour in the local sandstone. However, we managed to squeeze in a visit to the old fort at Amer, as well as to see the Sisodia Rani Bagh, missed on earlier visits.

Amer fort was earlier a small settlement of the tribe of Meenas, dedicated to the goddess Amba. This was taken over by the Raja Man Singh, who camped there one night, and on being told (if the sound and light show is to be believed) that the place belonged to the Meena tribe, laughed and said, `it used to belong to them', and promptly took it over. A prominent feature of the fort is the temple of Sila Devi, who it is said, appeared to Raja Man Singh in a dream, and agreed to take up residence at his fort. The Devi instructed the king to lead the way to the place where he wanted to install her, and that she would follow, but he should not look behind. The king did lead the way, but at some point turned round to look at the goddess, who froze on the spot. Thus, the temple to the Devi got constructed at the entrance of the fort, and the image of the Devi (Mahishasur Mardini) turns around.(Less fanciful versions of the story can be found in Wikipaedia).

The fort boasts of the most beautiful marble inlays and jaalis, as does the temple, second to none in India, including the Taj Mahal. The fort overlooks the Maota lake, and a beautiful garden, with beds of

crocuses whose stamens yield the precious saffron. 

The structure follows the traditional pattern, being built around courtyards, with halls of audience, halls of recreation, pleasure garden, the zenana, and a sheesh mahal.

 The sound and light in the evening, lights up the huge fort in a very impressive fashion. The stories that it tells, however, are not as impressive. The Kachhvahas of Amer, Raja Man Singh and his descendants, were always courtiers of the Mughals, and the stories of those who fought with the Mughals, like Rana Pratap, and Shivaji are more interesting! Still, the spectacle is not one to be missed.

A  highlight of the visit  was a quick, unexpected  glimpse of the one of the current owners of Amer, Princess Diya, the step-granddaughter of Maharani Gayatri Devi of Jaipur,  a chip of the old block, chiffon, dark glasses and all. Here's  hoping for another visit, maybe to another place in Rajasthan, so that there can be a Land of Kings 3 post.

This blog post by Neelima Gupte and Sumathi Rao.

Rahul Basu (04/03/1956-05/03/2011)

Because he lived, next door a child
To see him coming often smiled,
And thought him her devoted friend
Who gladly gave her coins to spend.

Because he lived, a neighbor knew
A clump of tall delphiniums blue
And oriental poppies red
He'd given for a flower bed.

 Because he lived, a man in need
Was grateful for a kindly deed
And ever after tried to be
As thoughtful and as fine as he.

       Because he lived, ne'er great or proud
       Or known to all the motley crowd,
       A few there were whose tents were pitched
       Near his, who found their lives enriched.


 `Because he lived',  Edgar A. Guest.

This blog post is by Neelima Gupte and Sumathi Rao.

Kumbh Mela 2013 - A view from Jhusi

The Kumbh Mela, India's largest religious festival, is on right now. This year is supposed to be the Purnakumbh, which occurs only every 12 years. The festival is held at the Sangam (the confluence of the rivers Ganga and Jamuna) at Allahabad, as it happens, right next to the Harishchandra Research Institute, Jhusi, Allahabad where I  work. So here is a ringside view.

This is the time when the world converges on the moderately sized city of Allahabad, to have its dip in the Ganga on the designated snanam (bathing)  days (of which yesterday was one). A complete tented city comes up on the banks of the river, all ready to accommodate pilgrims, sadhus, halwais, tourists, hawkers, gawkers and what have you-s (that's us!). The pre-Kumbh preparations of the city had started over a year ago with the construction of new over-bridges, laying of new sewer lines, repairing of roads, etc. Given the  pace of work, it was hard to believe in October, that things would  actually get completed by the time the Kumbh began. However,  the great Indian `jugaad'  worked out finally and by January, everything was in place.  We, Jhusi residents,  saw the new Kumbh city develop in just a matter of weeks, in  an amazing and efficient fashion, complete with  lights,  water, the sewage, public toilets, sectors and roads, and a large number of pontoon bridges  (around twenty) across the Ganga, over areas which had been submerged just a few months ago.  We had seen this happen in 2001, however it was still awe-inspiring, especially given the functioning of the city  in  the remaining eleven years!

The tent city has tents  of all kinds, from  simple staying arrangements for the ordinary folk, to quite comfortable accommodation for the well off, with attached bathrooms, hot water, western style toilets, and  plants growing all around, transplanted from elsewhere! Besides these residential tents, there are the `pravachan' or discourse tents, which compete with one another in having fancy `architecture', lighting arrangements, like pooja pandals, elsewhere.

The first of the shahi snans was on Makar Sankaranti, January 14.  This year's bitter winter  kept many people away from the icy dip in January, but February saw an increase in numbers. Until then, the crowds were moving towards the sangam area and taking their dips in an orderly and well-behaved fashion. There were big tour groups from different Indian states, and a sprinkling of foreigners. Some of the groups  had designated gurus and would go to listen to their particular gurus, others would try out different tents. There were `superstar'  gurus with a huge number of followers whose tents were overflowing. There were those who were preaching to just a few faithful followers. There were young gurus out to make their names. Academic types thought  it was like a  `March meeting' on the subject of religion, with many parallel sessions!

The big day was  February 10th or Mauni Amavasya day, the most auspicious day, of the Kumbh, when more than 30 million people were expected in a small area of a   city which has  a normal population of less than 10 lakhs!  The day did not disappoint us. In the earlier days of the Kumbh, the `HRI akhada' as we called ourselves often went for walks in the mela as a group, to see the sights,  and eat hot jalebis!

This became impossible after February 9th.  The actual sangam area was closed to the general public from about midnight to about ten or eleven in the morning, because Mauni Amavasya is also the day of the second shahi snan of the ascetics, and the main bathing area was reserved for them. This did not deter the continuous procession of people going towards and away from the sangam with the one-point agenda of having a dip in the sangam and cleansing their sins!

Although most people managed to walk for miles, have a successful dip and find their way back, there were inevitable replays of the `lost in the Kumbh Mela' scenarios, beloved of Hindi movies.  Compounding the problem was the fact that many people spoke no language, other than their native tongue, and not a word of the local Hindi.  A young man from Andhra who spoke only  Telugu had lost his wife and child. One of our Telugu speaking friends helped him and took him to the `lost and found' centre (which has been functioning for decades with the help of volunteers)  in the Mela where they were allowing people to speak over the loudspeaker themselves in their own language. His story fortunately had a happy ending when he got re-united with his wife and child after two frantic days, in Varanasi, where his wife had also managed to independently reach the Andhra Samaj.

It was really nice to see that  the police were trying to be helpful, under quite difficult circumstances. I especially remember the commando lady, who after putting in an uncountable  number of hours on duty, went up to the pujaris to give her offering, before wending her weary way home.

The stampede at the railway station on the Mauni Amawasya day was a real tragedy and an unforgivable lapse on the part of the administration, as was the fire on the Basant Panchami day. Despite these serious problems,  before criticizing anyone, I would like to say that the mela administration, the police and the security people, the safai karmacharis who have kept the area clean and the local Allahabad administration have done an extra-ordinary job, extra-ordinarily well. The scale of the operation which has been carried out has to be kept in mind, before indulging in blame games, and what has gone wrong cannot take away all that has gone right.  Here's wishing for a perfect Kumbh, the next time round (in 2025)!

This blog post is by Sumathi Rao.

Another hanging

This Saturday saw another hanging, again in a terrorist related case. Afzal Guru, who was convicted as a conspirator in the 2001 attack on the Indian parliament, was hanged this Saturday in Tihar jail, again under the utmost security and secrecy. While this case looks superficially similar to Ajmal Kasab's, there are important and crucial differences. Guru was not one of the perpetrators of the actual attack. His crime was to provide shelter for the actual attackers, and to be involved in their financial transactions. Locking him away for his natural life could well have been been adequate punishment under the circumstances. Some of the evidence against Guru was circumstantial, and some under his own confession. Conspirators whose contribution to the assasination of Mahatma Gandhi was similar, were not awarded the death penalty. Senior jurists and human rights activists have been perturbed by this execution.  Rather than discourage terrorism, this hanging may provide support to the agenda of hate that fuels terrorism. Yes, the state should be strong, but some times strength lies in mercy. We hope the strength of mercy will be allowed to prevail in future cases.

This blog post  is by Neelima Gupte and Sumathi Rao

The IPA Rahul Basu Memorial Award

It gives us great pleasure to announce the names of the winners of the first IPA Rahul Basu Memorial award for the best thesis in High Energy Physics. The winners of the award are Dr. Lokesh Kumar (Ph.D. from Punjab University, presently at Brookhaven National Lab) for his thesis entitled "Identified particle production, fluctuations and correlations studies in heavy-ion collisions at RHIC energies" and Dr. Diptimoy Ghosh (Ph.D. from TIFR, presently at the University of Rome "La Sapienza") for his thesis entitled “Looking for physics beyond the Standard Model through flavour transitions.”

The quality of the nominated theses was very high, and the final choice was very difficult. Therefore it was decided to award two honourable mentions as well. These are Dr. Debasish Banerjee (Ph.D. from TIFR, presently at the University of Bern), for the thesis "Nonperturbative studies of strongly interacting matter at finite temperature and density", and Dr. Ketan Patel (Ph.D. from PRL/Mohanlal Sukhadia University, presently at TIFR) for the thesis, "Beyond the Standard Model Physics: Grand Unification and otherwise". The prizes will be presented on 17th January at the XX DAE-BRNS High Energy Physics Symposium which is being held at the Department of Physics, Visva-Bharati, Santiniketan. We hope to share further details of the award ceremony with you next week.


Update:

The award ceremony took place in the Physics department at Santiniketan on 17th January. The ceremony started with two short talks by Sunil Mukhi and Rohini Godbole on Rahul Basu, his personality and work. This was followed by a short interaction with the award winners Lokesh Kumar in the U.S. and Diptimoy Ghosh in Italy on Skype. The award winners had described their work in two excellent recorded talks.

Lokesh Kumar's work was related to constructing the phase diagram for QCD. For the construction of this phase diagram  a beam energy scan (BES) program was proposed at the Relativistic Heavy-Ion Collider Facility, BNL, USA in 2008. The experiment and Collider was asked to demonstrate the feasibility of RHIC carrying out this program below the injection energies. A test run was provided at center of mass energies of 9.2 GeV per nucleon for Au+Au collisions. A major part of Dr. Lokesh Kumar's thesis work was related to demonstrating that STAR experiment could  successfully carry out the BES program. With only 4000 events available in the short test run, he was able to provide convincing physics results which played a major role having approving the program approved at RHIC from the year 2010. The success of the analysis of the 9.2 GeV Au+Au collision data establishes the foundation for the subsequent beam energy program, one of whose primary objective is to locate the possible critical point in the QCD phase diagram. This was the importance of Lokesh Kumar's thesis.

The other awardee, Diptimoy Ghosh worked on flavour physics for his Ph.D.  An interesting aspect of his thesis is that it looks for signatures of processes beyond the standard model.  He played a major role in  identifying the new physics required for explaining the  large enhancement seen  in the [Bs to tau tau] decay rate. He had also worked on constraining specific new physics models using low-energy flavour-physics data in addition to the high-energy collider data from ATLAS and CMS, pointing out implications of a variety of interesting signals involving the anomalous decay rates, the top quark forward-backward asymmetry, searches  for Higgs and supersymmetric particles  in various channels, etc.

The talks were received very well. The awardees came back at the end of talks for a very lively question answer session.  We hope this award will inspire work of equally high quality in the coming years, and wish the awardees every success in their future careers.


This blog post is by Neelima Gupte and Sumathi Rao.