Student-Talks at the Department of Theoretical Physics (DTP) at TIFR


The idea is to have 2 students from TIFR give 2 talks every week. (An aim we are yet to achieve!)
One on Monday and one on Friday and if either requires an extra slot then it can be aranged somewhere in the middle of the week like Wednesday. The default venue is Theory Seminar Room A304 at 6Pm on the above mentioned days of the week.

Currently the talks are being scheduled as per alphabetical order of the email ids of the students of DTP. If other people want to be included in the list either for giving the talks or for receiving notifications then kindly inform me. Notifcations for the talks will be put-up here on this website and the speakers will be reminded of their slots one week in advance through private emails and will be requested to send me an abstract to be used in the public notice. The announcemnet of the talk on the day will be sent by public email to all students of DTP and to others who want to included in the list.

An incomplete tentative schedule with the talk titles is on the firstsheet of this file. The second sheet of the same file contains the list of names of speakers in alphabetical order.

I was offerring a token Rs.25 from my TIFR stipend to the speaker for his/her efforts to give the talk.
From 1st Februray 2010 onwards I increased the remuneration to Rs.35 for various technical reasons.
No tea or snacks will be arranged.


The 7 talks till now,


Date: 16th April 2010
Title: Z_2 invariance in topological insulators
Speaker: Sambuddha
Venue: A304
Time: 8:30Pm
Duration: 1Hour
Abstract:
In this talk I will try to answer the question that how Z_{2} invariance occurs in time reversal invariant systems like topological insulators. I will first introduce Laughlin's gedanken experiment to interpret IQHE and characterize the Hall integer as a topologically invariant number. Then I will follow the same line of argument to show that for a time reversal invariant system there exists a similar Z_{2} invariant. In order to show that we will treat time polarization in a similar fashion to the modern theory of charge polarization. Then I will use the Z_{2} invariant to characterize a band structure to get a fill of the physical system and to see how one can calculate this Z_{2} invariant for a real system. Once we know the way to characterize a topological insulator we can try to construct a general phenomenological model of topological insulator and identify all the existing models in the market under this general model.(But this part is subject to availability of time, a very much disjoint part from the previous one, may be subject of another talk)

Attended by: Tridib,Kabir,Anirbit



Date: 19th March 2010
Title: Quantum Spin Chains and Luttinger Liquid Theory
Speaker: Kabir
Venue: A304
Time: 8:30Pm
Duration: 1Hour
Abstract:
The talk is a general description of a Luttinger liquid, its properties and how it differs from a Fermi liquid. 1 D quantum spin chains and their description in terms of Luttinger liquids will be discussed( including the spin 1/2 Heisenberg model and its solubility by the Bethe Ansatz).
Reference on Luttinger Liquid
Reference on Bethe Ansatz
Reference on 1-D Fermi Fluid

Attended by: Kusum,Loganayagam,Nikhil,Rahul,Sambuddha,Anirbit.



Date: 19th February 2010
Title: Deconfined Criticality
Speaker: Argya
Venue: A304
Time: 6:30Pm
Duration: 2Hours
Abstract:
From Landau theory, transitions from an 'Antiferromagnetic' phase to a 'valence bond solid' phase is expected to be first order in nature. The theory of 'deconfined criticality' proposes continuous transition between the two phases. If realised in nature, these are possible exmaples of phase transitions where Landau theory does not work.

Attended by: Kusum,Prithwi,Tridib,Jyotirmoy,Shawnmoy,Sambuddha,Debashish,Anirbit.



Date: 8th February 2010
Title: Cosmological Perturbations
Speaker: Rahul
Venue: A304
Time: 6Pm
Duration: 2Hours
Abstract:
I will try to give an overview of cosmological perturbation theory, which is to say how you handle the situation which arise when the universe isn't a pure FRW homogenous-isotropic one. I plan that it'll be a heuristic development, so more of a how-i-understand-how-this-comes-about thing rather than here-it-is-and-now-lets-see-various-solutions-oh-here-is-the-radiation-dominated-one thing. As for what this cosmological perturbation theory actually is, the shortest paper on the subject I could find is astro-ph/0101009. I assume a knowledge of GR. Can't say 'basic', because I don't know what exactly basic is. But uncomplicated.

Attended by: Shawnmoy,Nikhil,Mononeeta,Sambuddha,Preeti,Anirbit and Amaresh (attended for sometime).



Date: 1st February 2010
Title: Xtreme QCD
Speaker: Debashish
Venue: A304
Time: 6Pm
Duration: 1Hour
Abstract:
The aim is to try to discuss the phase diagram of QCD and QCD-like theories under extreme conditions of temperature and density. To appreciate what goes on at such extreme conditions, we need to examine the salient features of these theories such as confinement and chiral symmetry breaking and connections between them.

Attended by: Sambuddha, Sanmay, Jyotirmoy, Anirbit, Kabir and Kusum.
Loganayagam came in at the very end.



Date: 29th January 2010
Title: A review of the article "What is Gauge?' by Terence Tao (Part 2)
Speaker: Anirbit
Venue: A304
Time: 6Pm
Duration: 1Hour

Abstract:
We continue reviewing the mentioned article by Terence. Today I hope to clean up a bit more of Terence's idea of taking quotient of the space of line segments by congruences. Then we will go through Terence's way of motivating the idea of "connections" and hopefully give examples of local structure groups. May be we will digress a bit at the end to see how the idea of structure group also makes sense for combinatorial objects like a directed graph.

Attended by: Kabir,Sambuddha and Imon



Date: 25th January 2010
Title: A review of the article "What is Gauge?' by Terence Tao (Part 1)
Speaker: Anirbit
Venue: A304
Time: 5:30Pm
Duration: 1Hour

Abstract:
I have been recently reading the above linked article on Gauge Theory and I found the exposition by Terence Tao very masterful (like any of his other writings!). You are encouraged to find out more about the author Terence Tao if you have never heard of him so that you can be fully convinced as to why it is worth trying to understand his analysis about anything! I was finding it more insightful than others I have come across. I haven't yet read the full article but I hope to read along while I explain whatever I have covered. I believe that trying to explain what I am reading helps the process of reading especially when the content is so very complicated like this one is!

Attended by: Rupal,Sanmay,Nilay,Sambuddha,Imon,and another person!
Loganayagam came in towards the middle.