University of Crete HEP Seminars Spring 2012
| Speaker: |
Rene Meyer |
| Department: |
University of Crete |
| Slides: |
[PDF] |
| Time: |
Friday 17 February 2012 at 14:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
We study relativistic hydrodynamics of normal fluids in two spatial dimensions. When the microscopic
theory breaks parity, extra transport coefficients appear in the hydrodynamic regime, including the Hall viscosity and the anomalous Hall conductivity. I present a classification of all these transport coefficients in first order hydrodynamics.
All the parity-breaking transport coefficients turn out to be dissipationless,
and some of them are related to the thermodynamic response to an external magnetic field and to vorticity.
In addition, I give a holographic example of a strongly interacting relativistic fluid where the parity-violating transport coefficients are computable. |
| Speaker: |
Andy O'Bannon |
| Department: |
Cambridge U., DAMTP |
| Slides: |
[PDF] |
| Time: |
Tuesday 21 February 2012 at 15:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
Topological Insulators (TI's) are materials characterized by gapless edge states producing quantized, dissipationless transport. In more formal terms, they are defined as insulating materials characterized by a topological quantum number distinct from the vacuum. They thus fall outside the Landau-Ginzburg paradigm in which materials are classified by symmetry-breaking order parameters. Examples of TI's include quantum Hall systems, for which the topological quantum number is an integer (the quantized Hall conductivity), and recently-discovered materials for which the topological quantum number is Z2-valued. These systems all admit effective descriptions in terms of non-interacting electrons. Indeed, a complete classification now exists of all possible TI's described by non-interacting electrons. An open question is what kinds of TI states are possible in the presence of interactions. Gauge-gravity duality, or holography, gives us access to strongly-interacting systems, including some special TI's. In this talk I will describe one example a "holographic topological insulator," and compare the potential that a test charge feels in the presence of that TI, as computed from Wilson loops, to the result for real TI's.
|
| Speaker: |
Hong Bao Zhang |
| Department: |
University of Crete |
| Time: |
Tuesday 28 February 2012 at 14:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
General relativity tells us gravity is geometry. But this is not the end of the story for many reasons. In particular, gravity may be identified as sort of holographic object at the end of day. In this talk, I will report our ongoing work towards that goal. To be more precise, I will show that within the context of general relativity various kinds of entropy production on the boundary correspond exactly to the horizon area increase of black hole in the bulk. The result obtained is fantastically generic in the sense that it does not require the spacetime in question to be asymptotically AdS, or the boundary to be conformal boundary, and so on, so forth. |
| Speaker: |
Matti Järvinen |
| Department: |
University of Crete |
| Slides: |
[PDF] |
| Time: |
Friday 2 March 2012 at 13:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
After an introduction to Hilbert series, I discuss my recent work (arXiv:1112.5454) on the Hilbert series of N=1 supersymmetric QCD with U(N_c) and SU(N_c) color symmetry. I use two methods to compute the series, which have previously been applied to similar computational problems in the analysis of decay of unstable D-branes: expansions using Schur polynomials, and the log-gas approach related to random matrix theory.
|
| Speaker: |
Elli Pomoni |
| Department: |
Humboldt University |
| Slides: |
[PDF] |
| Time: |
Tuesday 6 March 2012 at 14:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
N = 2 Super Conformal QCD is perhaps the simplest theory outside the N
= 4 "universality class" that we can attempt to study holographically.
It is moreover continuously connected to the N = 4 class by an
interpolating family of N = 2 SCFT. Careful analysis of its chiral
spectrum points towards a gravity dual description via a non-critical
string background. We concentrate on the study of spin chains. The
complete one-loop Hamiltonian and some higher-loop results already
reveal a rich dynamics. We present past results and current progress.
|
| Speaker: |
Ioannis Iatrakis |
| Department: |
University of Crete |
| Time: |
Friday 9 March 2012 at 13:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
The study of the transverse part of the vector-axial vector flavor current correlator in the presence of weak external electric field is presented. The correlator is calculated using a bottom-up AdS/QCD model, that includes both
contributions of higher string states and the non-linear dynamics of the chiral condensate. It is shown that for low momenta the result agrees with the relation proposed by Son and Yamamoto motivated by a simpler holographic model. This suggests that the Son-Yamamoto relation is generically valid in the IR of models with the proper chiral symmetry breaking pattern. |
| Speaker: |
Andy O'Bannon |
| Department: |
Cambridge U., DAMTP |
| Time: |
Tuesday 13 March 2012 at 14:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
TBA
|
| Speaker: |
Takeshi Morita |
| Department: |
University of Crete |
| Time: |
Friday 16 March 2012 at 13:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
We consider an Euclidian black Dp brane localized on an S^1 circle and take a near horizon limit by keeping the radius of the circle finite.
We find that a potential for the center mass of the brane along the S^1 direction appears and this potential breaks the continuum translation symmetry along the S^1 direction to a discrete Z_N symmetry where N is the charge of the brane.
Thus the position of the brane is restricted to the discrete values in low energy.
This phenomenon is related to the fact that the dual gauge theory is SU(N) rather than U(N).
This would be important in the study of the Gregory-Laflamme transition in holography.
We also discuss an application to holographic QCD in the D4 brane model.
|
| Speaker: |
Ioannis Papadimitriou |
| Department: |
Instituto de Fisica Teorica (IFT UAM/CSIC) |
| Time: |
Friday 23 March 2012 at 13:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
It known that the SO(6)xSO(2) symmetric one-scalar consistent truncation
of N=8 gauged supergravity in four dimensions is related via a field
redefinition to a conformally coupled scalar coupled to Einstein-Hilbert
gravity
and with a simple quartic self interaction. However, only a subset of
the solutions in the conformally coupled frame
can be translated to solutions in the minimally coupled frame, since for
certain solutions the aforementioned
field redefinition becomes singular. I will present a novel Z_2 on-shell
symmetry of this system in the conformally coupled frame, corresponding
to a duality between the cosmological constant and the quartic coupling,
and
I will argue that this symmetry leads to a doubling of the solution
space. The quotient of the solution space
in the conformally coupled frame by this Z_2 symmetry can then be
identified with the solution space in the
minimally coupled frame, thus establishing the equivalence between the
two descriptions of this sector of
N=8 gauged supergravity in four dimensions. |
| Speaker: |
Amos Yarom |
| Department: |
Technion |
| Slides: |
[PDF] |
| Time: |
Tuesday 27 March 2012 at 14:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
I'll discuss the role of an entropy current in constraining the equations of motion of relativistic hydrodynamics especially in theories in which parity is violated. After giving a few holographic examples of parity violating fluids I will discuss how one may obtain the same constraints on the equations of motion using equilibrium properties of the system. |
| Speaker: |
Hugh Osborn |
| Department: |
Cambridge University |
| Slides: |
[PDF] |
| Time: |
Thursday 29 March 2012 at 11:15 ( Time has been changed from the previous announcement!!) |
| Venue: |
The ground floor room 1 (Aithousa 1) of the physics department ( Irregular location ) |
| Abstract: |
The superconformal index can be determined using just the R charges and representations for a superconformal theories in four dimensions. For theories related by Seiberg duality the index for the different theories should be identical. The mathematical identities required have been proved in just the past few years and are very non trivial. The index identities may provide a new link between theoretical physics and some parts of pure mathematics.
|
| Speaker: |
Aristomenis Donos |
| Department: |
Imperial College |
| Slides: |
[PDF] |
| Time: |
Friday 30 March 2012 at 11:15 ( Time has been changed from the previous announcement!!) |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
The AdS/CFT correspondence is a powerful tool to analyse strongly coupled quantum field theories. Over the past few years there has been a surge of activity aimed at finding possible applications to condensed matter systems. One focus has been to holographically realise various kinds of phases via the construction of fascinating new classes of black hole solutions. In this framework, I will discuss the possibility of describing finite temperature phase transitions leading to spontaneous breaking of translational invariance of the dual field theory at strong coupling. |
| Speaker: |
Adam Schwimmer |
| Department: |
Weizmann Institute |
| Slides: |
[PPT] |
| Time: |
Monday 2 April 2012 at 11:15 (Irregular Date and Time) |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
The general proof of the a-Theorem using Trace Anomaly Matching will be discussed. An alternative argument for massive flows will be outlined and compared with the general proof. |
| Speaker: |
Yiota Foka |
| Department: |
GSI |
| Slides: |
[PPT] |
| Time: |
Tuesday 3 April 2012 at 14:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
After almost two decades of preparation ALICE, the dedicated heavy ion experiment
at the CERN LHC, took first data with proton collisions at the end of 2009 and with
lead beams at the end of 2010 at a cetre-of-mass energy of 2.76 TeV/nucleon.
An overview of the ALICE results from the first Pb-Pb run is presented. |
| Speaker: |
Yiota Foka |
| Department: |
GSI |
| Time: |
Wednesday 4 April 2012 at 15:15 |
| Venue: |
The 3rd floor seminar room of the physics department |
| Abstract: |
After almost two decades of preparation ALICE, the dedicated heavy ion experiment
at the CERN LHC, took first data with proton collisions at the end of 2009 and with
lead beams at the end of 2010 at a cetre-of-mass energy of 2.76 TeV/nucleon.
An overview of the ALICE results from the first Pb-Pb run is presented. |
| Speaker: |
Song He |
| Department: |
MPI in Postdam |
| Slides: |
[PDF] |
| Time: |
Tuesday 24 April 2012 at 14:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
We derive a set of equations obeyed by the S-matrix of planar N=4 SYM. The equations render the S-matrix invariant under a suitably defined Yangian symmetry, and determine it at any value of the coupling. When expanded in powers of the coupling, they give derivatives of amplitudes as single integrals over lower-loop ones. We apply them on a few examples, deriving a recent result on the two-loop NMHV and fixing previously unknown coefficients in a recent Ansatz for the three-loop MHV amplitudes. |
| Speaker: |
Umut Gürsoy |
| Department: |
CERN |
| Slides: |
[PDF] |
| Time: |
Wednesday 2 May 2012 at 15:15 |
| Venue: |
The 3rd floor seminar room of the physics department |
| Abstract: |
I will review two new developments in applied AdS/CFT correspondence. The first application is concerned with the thermodynamics of the quark-gluon plasma. In particular, I will explain how the holographic description of the thermodynamics of SU(N) gauge theories can explain a universal behavior observed in the interaction measure $T^\mu_\mu$ as a function of temperature, in 3+1 and 2+1 dimensions. The second development is about how to holographically describe physics of elementary fermionic excitations in cold atom systems. |
| Speaker: |
Jürgen Schukraft |
| Department: |
CERN |
| Time: |
Thursday 3 May 2012 at 17:15 |
| Venue: |
The 3rd floor seminar room of the physics department |
| Abstract: |
At the end of 2010, the CERN Large Hadron Collider started
operation with heavy ion beams, Lead on Lead at a centre-of-mass
energy of 2.76 TeV/nucleon, opening a new era in ultra-relativistic
heavy ion physics at energies exceeding previous accelerators by
more than an order of magnitude. This talk summarizes the results
from the first year of ion physics at the LHC obtained by the three
experiments participating in the ion program, i.e. ALICE, ATLAS, and
CMS; comparing them where appropriate with data from lower
energies (RHIC and SPS), and focusing on areas where significant
progress has been made in the study of hot and dense matter, the
Quark Gluon Plasma. |
| Speaker: |
Christos Charmousis |
| Department: |
Univ. Paris-Sud |
| Slides: |
[PDF] |
| Time: |
Monday 7 May 2012 at 15:15 |
| Venue: |
The 3rd floor seminar room of the physics department |
| Abstract: |
We will discuss the cosmological constant problem in the context of
self-tuning scalar tensor theories in 4 dimensions: can a scalar self-tune
to an abruptly changing cosmological constant without affecting the
spacetime metric? After reviewing the most general scalar tensor theory
proposed in the 70 's by Hornedski we shall define and then apply the
self-tuning filter. The self tuning theory will be a scalar tensor theory
dubbed fab 4. We shall briefly discuss some of its geometric and other
properties. |
| Speaker: |
Toby Wiseman |
| Department: |
Imperial College |
| Time: |
Tuesday 8 May 2012 at 14:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
QFT in fixed curved spacetime is a fascinating subject. This is particularly true for black hole spacetimes, such as Schwarzschild where one expects to see Hawking radiation.
In free or weakly coupled QFT one can compute this explicitly. In this talk I will describe how AdS-CFT allows us new tools to compute results for certain strongly coupled CFTs.
Such calculations require that we construct a specific (and rather exotic) black hole solving 5-d Einstein equations with a negative cosmological constant.
I will very briefly describe how new numerical techniques allow this to be done, and will show a solution that, via AdS-CFT, describes certain strongly coupled CFTs on a fixed Schwarzschild background.
Interestingly we shall see that in this case, the expectation gained from the free field intuition completely fails to describe these strongly coupled results, where in fact Hawking radiation is hugely suppressed. This is closely related to the existence of black holes on Randall-Sundrum branes which I will also discuss and show results for. |
| Speaker: |
Blaise Goutéraux |
| Department: |
APC, Paris |
| Slides: |
[PDF] |
| Time: |
Thursday 10 May at 15:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
Einstein-Maxwell-Dilaton theories have recently attracted a lot of
attention in holography. In this talk, I will explain how they may
derive from scale invariant theories using generalised dimensional
reduction, where the number of reduced dimensions is traded against a
real, analytically continued parameter. This technique allows to
generate easily new black hole solutions (or recover know ones) in
gravity plus scalars theories, explains their scaling properties, as
well as facilitates the computation of holographic observables such as
the shear viscosity and other transport coefficients. |
| Speaker: |
Liuba Mazzanti |
| Department: |
Santiago de Compostela U. |
| Slides: |
[PDF] |
| Time: |
Tuesday 15 May 2012 at 14:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
We analyze the holographic gravity model dual to a quark-gluon plasma with massless dynamical quarks in the Veneziano limit. The background of smeared D7 branes in a D3 near horizon geometry is reviewed. On top of this we add probe D7 branes to produce results for phenomenologically relevant quantities such as the meson melting phase transition point, the screening length, the drag force and diffusion constants for a heavy quark.
|
| Speaker: |
Vasilis Niarchos |
| Department: |
Crete U. |
| Time: |
Tuesday 22 May 2012 at 14:15 |
| Venue: |
The 2nd floor seminar room of the physics department |
| Abstract: |
I will discuss recent work on the mathematics of a 3d/4d connection that relates
Seiberg duality for d=4 N=1 SQCD theory to Aharony/Giveon-Kutasov dualities for d=3 N=2 SQCD
theories.
|
