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 I Sunday, Jan 14 2007 

A collection of interesting posts from physics blogsphere :

Short Distances: Newton Still the Man (from Cosmic Variance by Sean)

Via Chad Orzel, I see that the latest constraints on short-distance modifications of Newton’s inverse-square law from the Eot-Wash group at the University of Washington have now appeared in PRL. And the answer is: extra dimensions must be smaller than 0.045 millimeters (in any not-too-contrived model)…

Undergraduate Theory Institute(from Cosmic Variance by Sean)

Sadly, I’m not here to announce that applications are now being accepted for students who would like to participate in this year’s Undergraduate Theory Institute. That’s because there is no such thing as the Undergraduate Theory Institute, at least as far as I know. (Google doesn’t know of one either.) But I think it would be a great idea — maybe if I post it here on the blog someone will start it.

It’s increasingly common for physics students to participate in some kind of research during their undergraduate years. The NSF has a very successful Research Experience for Undergraduates program, for example, that funds students to do summer research, typically at an institution other than their own. Getting involved in research as early as possible is a great idea for students, for a number of reasons. Most importantly, the flavor of doing real research, where the answers aren’t in the back of the book, is utterly different from almost any classroom experience or even self-study, where you are trying to learn material that someone else has already mastered. The move from following a course of study to striking out into the unknown is one of the hardest transitions to make during graduate school, and getting a head start is an enormous help. On a more prosaic level, it’s useful to work closely with an advisor who can end up writing letters of recommendation. And let’s not forget that it can be a lot of fun!..

Dancing Ball Lightnings in the Lab (from Backreaction Blog)

Ball lightnings are mysterious things: Small, bright balls of fire suddenly appear during a thunderstorm, swirl around, make sometimes funny noises, and leave behind a smell of ozone…

Since ball lightnings are not only spooky, but also very elusive, there has been a lot of speculation how to understand and explain them in a scientific way: People have suggested that it may be some ionised balls of plasma held together by their own magnetic fields, or even such exotic things as mini black holes leftover from the big bang…

A more “down to Earth” explanation was proposed in a 1999 Letter to Nature:..

From Griffiths to Peskin: a lit review for beginners (From “An American Physics Student in England” )

a.k.a. “How to get started learning QFT as an undergraduate.”

Quantum Field Theory (QFT) plays a key role in all branches of theoretical physics. For students interested in high energy theory, exposure to QFT at any early stage is slowly becoming the standard for top American graduate schools. This is already the case for the Mathematics Tripos at Cambridge…

An inspired student with adequate background should be able to take quantum mechanics in his/her second or third year and then progress directly to a ‘real’ QFT course with a bit preparation, without going through the rigmarole of a year-long graduate quantum mechanics course.

Instead, I present a rough guide to pedagogical QFT literature so that a motivated student can prepare for a graduate-level QFT course or a get started with a self-study during the summer after his/her undergraduate quantum mechanics course. As a someone who was in this position in the not-too-distant-past, I hope some personal experience with the pros and pitfalls of the listed texts will be helpful for other other students interested in doing the same….

Supersymmetry series at TowardsTengen Friday, Jul 7 2006 

Background: Nothing more than basic Quantum Mechanics, actually. Knowing a bit of QFT would be useful, but not essential.

I’m trying to write up a bit about what I’ve been doing, the first (badly written) installment is up here.  In case you check it out, let me know if there are any errors or mistakes.

Enjoy Physics …

Link Dump Friday, Jul 7 2006 

This post is mainly a collection of a lot of nice links to Physics related resources. Enjoy! :

And the best for the last …

  • John Baez:
  • Baez is a mathematical physicist at the university of California. He writes a weekly column on This Week’s Finds in mathematical Physics. Wonderfully written, and a really nice source of information of all sorts. This may require a little bit of maths, but he writes in a lucid and interesting way that even if you’re in your first year, UG, you will definitely learn something from each article, and the good news is there are archives going back to around 200 weeks!

  • Mark Sredniki:
  • This is a nice QFT book, it’s available online now, soon, it’s going to be taken off after it is published in print, so hurry and get your copy now! [Thanks to Tarun, for pointing this on out]. I’ve seen this once earlier, and it seemed really nice, especially has a nice section on spinors, and dotted & undotted indices, unless I’m confusing it with something else.

A hint of renormalization Friday, Apr 21 2006 

Background : Some amount of Quantum Field theory would help. Though the article doesnot go very much deep into quantum field theory as such, it is a bit difficult to understand the context of renormalisation, if you’ ve not seen it either in field theory or statistical mechanics.

Link :

A hint of renormalization
Authors: B. Delamotte
Comments: 17 pages, pedagogical article
Subj-class: High Energy Physics – Theory; Statistical Mechanics
Journal-ref: Am.J.Phys. 72 (2004) 170-184

An elementary introduction to perturbative renormalization and renormalization group is presented. No prior knowledge of field theory is necessary because we do not refer to a particular physical theory. We are thus able to disentangle what is specific to field theory and what is intrinsic to renormalization. We link the general arguments and results to real phenomena encountered in particle physics and statistical mechanics.

The abstract says it all. And yeah, all the best for endsems everyone 🙂

Update : See also

Renormalization of a model quantum field theory(should be accessible inside IITK)

Per Kraus and David J. Griffiths
Physics Department, Reed College, Portland, Oregon 97202

(Received 9 December 1991; accepted 30 April 1992)

Renormalization is the technique used to eliminate infinities that arise in quantum field theory. This paper shows how to renormalize a particularly simple model, in which a single mass counterterm of second order in the coupling constant suffices to cancel all divergences. The model serves as an accessible introduction to Feynman diagrams, covariant perturbation theory, and dimensional regularization, as well as the renormalization procedure itself. ©1992 American Association of Physics Teachers

Posted by : Loganayagam.R.(Tom)

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?

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

Symmetry breaking Saturday, Apr 1 2006 

Necessary Background: Not much as the article starts out at a sort of popular science level, but those of us doing Particle Physics now, may appreciate this a bit more.


Comment: This blog is quite interesting by the way, with a lot of interesting discussions by a few High energy and Astrophysics people, so check it out when you have the time at or

Posted by: Shanth