Supersymmetry on Lattice : An Introduction Wednesday, Jul 4 2007 

Last week, I gave a presentation titled “Supersymmetry on Lattice- An Introduction”[PDF] as a part of a course on Lattice Field theory.

It was an attempt at outlining the broad issues that arise when one tries to put Supersymmetry in Lattice. I have uploaded the presentation in the link above – Readers comments and criticisms are welcome.


Physics Blogspeak : Part II Sunday, Jan 14 2007 

COSMOS Reveals the Cosmos (from Cosmic Variance by Sean)

The internet works so that we don’t have to! This week is the big annual meeting of the American Astronomical Society in Seattle, so expect to see a series of astro-news stories pop up all through the week. The first one concerns a new result from the Cosmological Evolution Survey (COSMOS) — they’ve used weak lensing to reconstruct a three-dimensional image of where the dark matter is.

AAS Report #3: Things that go boom! (From Bad Astronomy Blog)

It’s a fact of life that some stars explode. Actually, it’s a good thing: when stars explode they create and scatter the heavy elements that create us. The iron in your blood and the calcium in your bones were created in a supernova! So it’s important to study these objects, so we can better understand our origins.

But it’s also fun! Stars explode! Bang! Cool!

Today there were three press releases about supernovae. All three were surprising to me, and pretty interesting.

1) Kepler’s Supernova was a Type Ia

OK, so that title doesn’t thrill you. But that simple statement is actually the answer to a long-standing mystery. Ready for this? OK, sit back…

The AAS : a Nerd’s Eye View (from Galactic Interactions)

I’m in Seattle at the moment. I flew in yesterday; it’s cold, windy, and rainy. In fact, the rain was looking kinda slushy last night. While my wife from Minnesota might scoff at my calling this cold (it was just below freezing), in Nashville it’s been March-like temperatures.

I’m here for the 209th meeting of the American Astronomical Society. I’m going to try an experiment. I’ve never done the “live blogging” thing before, and indeed it’s entirely possible that I’m not using the term properly. It is my intention to post several posts this week inspired by things I see at the AAS. I can’t tell you what they will be yet, because they haven’t happened…. I’m hoping mostly to focus on interesting science and such, but anything that inspires me to blather is fair game as far as I’m concerned….

(Other posts in this series.)

Come On In, the Methane’s Fine (from Uncertain Principles by Chad Orzel)

The Times has an article announcing the discovery of methane lakes on Titan:

CDF’s New Results : W Boson Mass and Top quark Mass (From Quantum Diaries)

1)And the W mass is …
2) A summary Mw-Mt plot for Christmas 2006
3) More thoughts on the W mass
4) A new precise top mass measurement with jets
5) The new number

Yuzik, Are you a theorist ? Saturday, Jul 8 2006 

Isaac Pomeranchuk
© Moscow Engineering Physics Institute (state university), 2002

Via Amar, I came to know of an interesting quote attibuted to a physicist called Pomeranchuk. In the words of L.B.Okun

When I became a student of Pomeranchuk in 1950 I heard from him a
kind of a joke that the Book of Physics has two volumes: v.1. is “Pumps
and Manometers”, v. 2. “Quantum Field Theory”.

As I read this quote, I suddenly realised that I know near to nothing about Pomeranchuk ! So, after some digging around I came across a short biography at ArXiv. According to the author of that biography,

In 1934-35 his [Pomernachuk’s] advisor became Alexander Iosifovich Shalnikov (1905 – 1986).
Many years later academician Shalnikov recalled that he started by bringing
Yuzik to a room full with old vacuum pumps glass-ware and leaving him
there. Two weeks later, entering the room, Shalnikov found that everything
that could be broken was broken. ‘Yuzik, are you a theorist?”, – uttered
Shalnikov. “I don’t know. And what?” – was the answer.

And hence the title of this post . 🙂

As you might expect, apart from the above biography, it is very difficult to find material on Pomeranchuk on the web. So, I would rether list here some miscellaneous links dealing with his work.

Approach to Absolute Zero – 4. Below 10 milli-Kelvin by R Srinivasan , A Resonance article has a section on Pomeranchuk cooling.

If a mixture of liquid and solid
3He is compressed isentropically
below 0.3 K, part of the liquid turns into solid absorbing heat
and the temperature of the liquid falls. This is the principle
of Pomeranchuk cooling.

And to quote the wikipedia article on Pomeron,

In physics, the Pomeron is a force-carrying pseudo-particle postulated in 1961 to explain energy behavior of soft hadronic collisions at high energies. It appeared first in the framework of the phenomenological Regge theory of strong interactions at high energies, but later a similar object was derived from the first principle QCD calculations.

The existence of the pomeron as well as some of its properties have been reasonably well established experimentally, notably at Fermilab. In particular, it is believed that the pomeron carries no net charges. The absence of electric charge implies that pomeron exchange does not lead to the usual shower of Cherenkov radiation, while the absence of color charge implies that such events do not radiate pions.

This is in accord with experimental observation. In high energy proton-antiproton collisions in which it is believed that pomerons have been exchanged, a rapidity gap is often observed. This is a large angular region in which no outgoing particles are detected.

The name honors the Ukrainian physicist Isaak Pomeranchuk for his theoretical work in 1960’s on high-energy scattering.

Some other articles on Pomeron :

And I would be happy to include any other link about Pomeranchuk which might turn up in the comments section.

“Electroweak Interactions” by Georgi Wednesday, Jul 5 2006 

Howard Georgi

Background : Quantum Field theory

Link : Weak Interactions – Howard Georgi

This is an online version of a monograph by Howard Georgi on Weak interactions. Do check out his homepage too . There are other interesting material including a review on effective field theory .

And I don’t know what to make of the B.A. thesis titled Les Phys by P.J.Dong (PDF file) linked from there. It seems like a drama with lots and lots of physics songs 🙂

And also check out another link from his webpage which points to some interesting articles on women in science. It includes the PDF slides and a streaming video of Georgi’s own lecture titled Women and the Future of Physics

2001- A Spacetime Odyssey Friday, Jun 9 2006 

Martinus Veltman, Recipient of 1999 Nobel Prize in Physics

Via Amar, I came to know of a treasure-trove of web lectures named 2001- A Spacetime odyssey. As far as the required background is concerned , I guess it is one of those things where nothing is reallly sufficient 😉

These web lectures are a part of a web-lecture archive. To quote

The Web Lecture Archive Project is a joint venture between the UM-ATLAS Collaboratory Project, the University of Michigan Media Union, and CERN, the European Laboratory for Particle Physics. Its goal is to implement this electronic archival system for slide-based presentations on the Internet.

Actually, there are much more material in that site than you might realise at first glance. Try for example , The CERN Academic Training lectures(2000) which is a kind of overview of particle physics. Especially, have a look at the lecture titled An Introduction to Field theory by Kleiss. You can find the lecture notes for these lectures here. I guess the required background is some amount of quantum mechanics, though I might be wrong…..

Then, there is the lecture by Veltman at CERN just after his Nobel prize. And there are some presentations by undergraduates at University of Michigan as a part of undergraduate research programme there.

The last but not the least is of course a series of popular science lectures called saturday morning physics at U.Mich. I especially loved the lecture titled
Quantum Tornadoes Near Absolute Zero by Paul Haljan. If you haven’ t seen it already, you should definitely see it. After all, it’s a popular science lecture so it should be accessible to everyone.

And this is Paul Haljan for you


And by the way, in case you didn’t notice, this is the first post at blogphysica by an IITK alumni 😉 Happy Summer Holidays , everybody !

Life on the Lattice Monday, Apr 17 2006 

Background: This is a blog by two Physicists working on Lattice QCD, and although I can't exactly descibe a clear set of prerequisites, it is technical – a little background in QFT and related stuff is kind of required, I guess, though there's no harm in perusing through it and reading what you like or understand.

Link: Life on the Lattice

One good thing about this blog is that it prides itself on being a Physics blog and not a Physicist's blog

Posted by: Shanth

PS: Tom/Ravi do you guys know of a way that we can enable wordpress to automatically display the login name from which the post was made? If we get that done, then the three of us who have seperate wordpress logins can just post articles and the posted by thing will become automatic, and even the others can probably get accounts soon?

Review of Particle Physics Friday, Apr 14 2006 

Background : It is a concise review of the whole field of particle physics as it stands now. It also has some good review articles on cosmology.

Link : Reviews, Tables, and Plots
in the 2005 web update of Review of Particle Physics

Just to give a taste of links there you can see the articles on Big-Bang cosmology (Rev.) , Neutrino mass, mixing, and flavor change (Rev.) , Cabibbo-Kobayashi-Maskawa quark-mixing matrix and Quantum chromodynamics (Rev.)
I guess it would be quite useful for those who are giving their particle physics presentations in this weekend 🙂

All the best for the presentations !

Posted by : Loganayagam.R.(Tom)

A Question in Yang Mills theory Sunday, Apr 2 2006 

If the solution to Yang Mills equations in a local neighbourhood of space -time yields two different gauge fileds, are they both necessarily related by a gauge transformation in that neighbourhood.

If that is true, I  require a complete proof  and it would be helpful if somebody can suggest a good reference for this.

Posted By :Venkateshan