Graduate Lunch Club

Spring 2006 schedule of talks
When

Fridays, 12:00pm - 1:00pm

Location

Center for Theoretical Physics, building NE25
4th floor, CTP seminar room 4-107
Massachusetts Institute of Technology

Organizers

Vijay Kumar

The CTP Lunch Club meets at 12 noon in the CTP seminar room every Friday (provided that there are sufficient speakers). A light lunch will be provided begining at 11:50am (usually pizza, however some other options may be explored).

The seminars are designed for graduate students and should be accessible to all students. First year students are particularly encouraged to attend so that they may learn about research being performed in the CTP.

Workshops are aimed at teaching students about particular areas of research rather than presenting cutting edge research. The goal is learning, and to encourage participation, faculty are asked not to attend the workshop portion of these seminars.

Email notification of the club will be sent to the ctp-all, ctp-postdocs and ctp-students email lists as appropriate.

If you wish to speak, or have suggestions about speakers and/or possible workshop topics, please contact the organizer listed above.

February 17

Experimental Particle Physics Through The Ages
Eric Fitzgerald
MIT

A discussion of some of the most famous particle physics experiments from the
last century, with an emphasis on the techniques for creation and detection.
Then a look forward to the LHC and possible new discoveries there.

February 24

A "funny" interesting problem in "semi-quantum" gravity
Stefano Ansoldi
MIT

Interesting systems can be modelled by co-dimension one branes
in General Relativity; although their classical dynamics is a
well-established subject, the quantization procedure still presents some
dark sides. After giving an overview of the basic classical formalism
using a specific example, we then introduce a "funny" problem in the
semiclassical quantization procedure. We show how this problem raises
some issues about the Euclidean description of gravitational tunnelling
and comment about the interest that a more precise understanding of it
might have in connection with "semi-quantum" gravity.

March 3

Vortices Vacate Vales and other Singular Tales
Ari Turner
Harvard

If you ever wondered what it would be like to live in two dimensions, but couldn't find a good wormhole, (gedanken) experimentation on thin layers of superfluids turns out to be a fun alternative. The vortices in a superfluid film behave like particles--from ordinary fluid
mechanics arises a 1/r Coulomb force among these vortices. When the film is spread onto a curved surface, the vortices also interact
with the curvature of the surface. Although it is neat to imagine that
this force is like two-dimensional gravity, it can be explained more
accurately with another foray into fluid mechanics, and used to invent problems for a two-dimensional edition of Jackson.

March 10

LOFF Phase in QCD and Chromomagnetic (In)stability
Marco Ruggieri
University of Bari

We have recently proposed a model of color-superconductor which
describes the crystalline pairing (LOFF) among the quarks Up, Down and
Strange in high density QCD. After a brief introduction to color
superconductivity with three flavors, we discuss such a model. Moreover,
we show that the LOFF phase with three flavors is free from the pathology
of Chromo-Magnetic Instability.

March 17

Topological order and quantum entanglement
Michael Levin
MIT Condensed Matter Theory Group

Topological quantum field theories (TQFTs) were first discovered in 1989 in the context of string theory. Surprisingly, TQFTs also describe the low energy physics of certain quantum spin systems. These quantum spin systems are said to contain "topological order." But what exactly is topological order? In my talk, I will show that topological order manifests itself in nonlocal quantum entanglement in the ground state. I will introduce a quantity - called "topological entropy" that
measures precisely this nonlocal entanglement.

March 24 - at 1:00pm*

A Gentle Introduction to Lattice QCD
Patrick Varilly
MIT
(Note: This week's seminar will start one hour later than usual.)

QCD is a theory that resists perturbative analysis at low energies. I will
give an overview of lattice QCD, a numerical Monte Carlo approach to
calculating observables in this regime. I will start by showing an analogous
method to solving the Schroedinger equation numerically, and slowly
generalizing until we can solve full QCD. Then I will show some examples of
quantities others have calculated in the past from first principles, such as
particle masses, the potential energy between two static quarks (which shows
the principle behind confinement) and action densities in mesons, baryons and
the vacuum. Finally, I'll briefly mention some of my own work on mapping the
quark density in mesons and baryons with heavy quarks.

 
April 7

Constraining Torsion by Gravity Probe B
Yi Mao
MIT

Most torsion gravity theories adopt the interpretation that
the source of torsion is the intrinsic spin of elementary particles, and
that rotational angular momentum does not couple to torsion. We argue
that this interpretation is problematic, by explicitly showing a
counterexample that a rotating body generates torsion field in the
Weitzenbock spacetime with Hayashi-Shirafuji Lagrangian. Given that
torsion is coupled to rotational angular momentum, a gyroscope should
feel torsion. We investigate the way to test torsion gravity theories
by the spin precession of a gyroscope in Gravity Probe B. Modelling
Earth to be a uniformly spinning spherical massive object, the torsion
around Earth is determined by seven parameters by symmetry requirement.
We calculate the instantaneous precession rate of a gyroscope and its
Fourier moments along a circular polar orbit. A gyroscope experiment
such as Gravity Probe B can (1) test or rule out some torsion theories
(e.g. Hayashi-Shirafuji Lagrangian) by measuring the average rate (and,
if technically possible, higher moments) of the precession, and (2) test
the General Relativity by constraining the smallness of torsion
parameters.

 

April 14

Ads/CFT and an Index for Supersymmetric Gauge Theories
Suvrat Raju

 

April 21

Implications of the measurement of the B^0_S -\bar{B}^0_S mass difference
Zoltan Ligeti
MIT

 

April 28

Electromagnetic analogies in weak-field GR
Robyn Sanderson

 

May 5

Perturbative dynamics of non-commutative
(topologically massive, supersymmetric) QED

Nicola Caporaso

 

May 12

Spontaneous Parity Breaking at theta= 0 Gauge Theories
Dr. Peter Richard Crompton

 

May 19

Nu experiments
Phillip Harris
MIT-LNS

Because of the recent affirmation that neutrinos have mass, the number of
neutrino experiments has grow drastically. In this presentation, we will
discuss both the strengths and weaknesses of a number of the new and
proposed neutrino experiments. We will also survey some of their most
recent results as well as past important results.

 

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