Tentative Schedule
January 24
Speaker: Gregory Gabadadze, New York University
Title: "Massive General Relativity"
Abstract:
A recent progress on construction of a massive extension of General Relativity,
and its cosmological consequences will be discussed
January 31
Speaker: Shin’ichiro Ando, Caltech
Title: "Gamma-ray probes of new physics: Particle dark matter and intergalactic magnetic fields"
Abstract:
High-energy gamma rays keep revealing new aspects of the Universe,
thanks to the current telescopes such as Fermi, HESS, MAGIC, VERITAS,
etc.
One of the important goals for these telescopes is to study the
nature of dark matter, by looking for annihilation gamma rays. Because
dark matter is annihilating everywhere in the Universe, the diffuse
gamma-ray background will contain some information on dark matter. In
this talk, I introduce a new analysis method of the gamma-ray
background, by using the angular power spectrum. This way, one can
efficiently analyze spatial distributions of photons, and since dark
matter annihilation follows density in a different way from other
astrophysical sources, the angular power spectrum is also characteristic
and distinguishable. The dark matter can be identified in the angular
power spectrum with Fermi if its contribution is ~10% or more.
Another important physics that one can learn with gamma rays is
magnetic fields in intergalactic space. This is because distribution of
secondary photons from electromagnetic cascades is affected by magnetic
fields. We therefore analyzed stacked AGN images from Fermi data, and
found an anomalous excess compared with point-spread function. If this
is due to intergalactic magnetic fields, then the field value will be
around 1 femto-Gauss.
February 7
Speaker: Kai Wang, Institute for the Physics and Mathematics of the Universe, University of Tokyo
Title: "Top quark forward-backward asymmetry at Tevatron and the BSM candidates"
Abstract:
CDF collaboration has recently published various updated measurements on
top quark forward-backward asymmetry in 1101.0034. The measured total
asymmetry is significantly larger than the SM prediction from QCD NLO
calculation. In this talk, I will try to give a comprehensive theory
review on the Beyond Standard Model proposals to this anomaly,
discussing their features, potential problems as well as their immediate
predictions at the LHC.
February 11
Speaker: Mark Strikman, Penn State University
Title: "Forward double pion production in pp and dA scattering at RHIC: evidence
for multiple parton interactions, and proximity of the black disk
regime"
** Special seminar at 10:30 AM in 705 Pupin **
February 14
Speaker: Ira Rothstein, Carnegie Mellon University
Title: "Response Function Sum Rules for Ultra-Cold Atoms"
Abstract:
The scattering lengths of ultra-cold atoms can be tuned to be
arbitrarily large leading to strongly interacting many body systems.
What makes these systems particularly compelling is that at infinite
scattering length they manifest Schrodinger symmetry, which is the
non-relativistic analogue of conformal symmetry. As such, many field
theoretic techniques which previously had no physical applications can
now be tested in the laboratory. In this talk I will discuss how one can
use the operator product expansion in conjunction with dispersion
relations to generate sum rules for dynamical response functions in a
first principles systematic fashion.
February 21
Speaker: Guy Moore, McGill University
Title: "Second-Order Relativistic Hydrodynamics"
Abstract:
Hydrodynamics is the universal theory describing the behavior of fluids
when their space time variation is on scales longer than any
microphysical scale in the fluid. Relativistic hydro has applications
in heavy ion collisions and early Universe cosmology, and has seen a
surge of interest due to heavy ion experiments and theoretical
developments in AdS/CFT. I will explain what second order
hydrodynamicsis and why it is the minimum theory to study in the
relativistic case.Then I discuss some limitations of the theory,
including a new bound on how small the viscosity can be and a
complication in the rigorous definition of the viscous relaxation time
$\tau_\pi$.
February 28
Speaker: Dimitrios Giannios, Princeton University
Title: "Structure and radiation of relativistic jets"
Abstract:
Collimated, relativistic outflows have been observed or inferred to
originate from supermassive black holes in the centers
of galaxies, solar-mass compact objects in binaries and gamma-ray
bursts. A theoretical paradigm for jet formation has been developed
since the late 1970s that can account in a unifying manner for all
these sources. This paradigm envisions that jets come from rotating
objects (neutron stars, black-hole ergospheres, or accretion disks) with
strong magnetic fields that extract their rotational energy. Despite
recent progress in the field, we still lack a coherent
connection between the jet dynamics and the electromagnetic radiation
emitted by these sources. The guiding theme that I propose for such a
connection is the dissipation of magnetic energy in
the jet. This key process connects the aspects of
acceleration of jets, their interaction with the external medium,
and radiation mechanisms.
March 3
Speaker: Yuri Dokshitzer, CNRS - Paris VI
Title: "Questions on Multiparticle Production in QCD"
** Special seminar at 2:10 PM in 705 Pupin **
March 7
Speaker: Lee Smolin, Perimeter Institute
Title: "The Principle of Relative Locality"
Abstract:
We propose a deepening of the relativity principle according to which
the invariant arena for non-quantum physics is a phase space rather than
spacetime. Descriptions of particles propagating and interacting in
spacetimes are constructed by observers, but different observers,
separated from each other by translations, construct different spacetime
projections from the invariant phase space. Nonetheless, all observers
agree that interactions are local in the spacetime coordinates
constructed by observers local to them. This framework, in which absolute locality is replaced by relative
locality, results from deforming momentum space, just as the passage
from absolute to relative simultaneity results from deforming the linear
addition of velocities. Different aspects of momentum space geometry,
such as its curvature, torsion and non-metricity, are reflected in
different kinds of deformations of the energy-momentum conservation
laws. These are in principle all measurable by appropriate experiments.
We also discuss a natural set of physical hypotheses which singles out
the cases of momentum space with a metric compatible connection and
constant curvature.
March 28
Speaker: Diego Trancanelli, University of Wisconsin
Title: "Black holes from matrices"
Abstract:
In this talk we set up a study of the processes of black hole formation and thermalization using the gauge/gravity correspondence.
Our analysis is in the context of a matrix quantum mechanics, the
so-called plane-wave (or BMN) matrix model. We consider configurations of the model that correspond to the scattering of "fuzzy spheres" and
derive the spectrum of fluctuations around these configurations. We
find that when two fuzzy spheres intersect, classical tachyons can form at the intersection locus. We follow the time evolution of these
modes (also using numerical simulations) and speculate on their role
toward the possible thermalization of the system.
April 4
Speaker: Jessie Shelton, Yale University
Title: "The Top Forward-Backward Asymmetry at Tevatron and the LHC"
Abstract:
The anomalously large top forward-backward asymmetry measured at the
Tevatron is a striking result which, if borne out, requires new physics
at relatively low mass scales. Whatever this new physics may be, it
must carry some nontrivial flavor structure, and thus provides a first
hint for beyond-the-standard-model theories of flavor. I'll talk about a
model which connects the observed top forward-backward anomaly to
anomalies in B mesons, and discuss the discovery prospects for this and
other models at the LHC. I will further discuss prospects for measuring
the top forward-backward asymmetry at the LHC.
April 11
Speaker: Matthew Kleban, New York University
Title: "The Expanding Triniverse"
Abstract:
I will describe a class of time-dependent solutions in string- or M-theory that are exact with respect to alpha-prime and curvature corrections and interpolate in physical space between regions in which the low energy physics is well-approximated by different string theories and string compactifications. The regions are connected by expanding "domain walls" but are not separated by causal horizons, and physical excitations can propagate between them. Examples include solutions that interpolate between oriented and unoriented string theories, and also between type II and heterotic theories. These solutions can be weakly curved and under perturbative control everywhere and can asymptote to supersymmetric at late times.
April 18
Speaker: Henri Kowalski, DESY, Hamburg
Title: "Investigation of the QCD-BFKL Pomeron with the HERA data and the Pomeron/Graviton Correspondence in ADS/CFT"
Abstract:
In the talk I will show that HERA data can be described by a universal
gluon density which can be identified with a pomeron. The new precise
data on F2 allow to determine the properties of a Discrete-Pomeron
solution to the BFKL equation. The DP structure is strikingly similar to
the closed-string, hard wall pomeron in ADS/CFT.
** Special Particle-Nuclear/ Theory seminar at 2:10 PM in 831 Pupin **
April 25
Speaker: Sean Hartnoll, Stanford University
Title: "Holography and Quantum Matter"
Abstract:
This talk will be an overview of recently developed holographic
approaches to strongly interacting condensed matter systems. I will
explain why certain theoretical and experimental challenges in
unconventional materials may be amenable to a holographic approach. From a theoretical perspective I will argue that holography provides new
computationally controlled entry points into non-Fermi liquid phases
and the emergence of superconductivity from such phases. I will also
argue that holography makes explicit the natural observables of strongly
correlated media that suggest novel emphases for theoretical and
experimental studies. I will not assume any previous knowledge of
holography.
May 16
Speaker: Arthur Kosowsky, University of Pittsburgh
Title: "Peculiar Velocities as a Probe of Dark Energy"
Abstract:
Peculiar velocities of galaxies and galaxy clusters contain a
significant amount of information about the growth of structure and the
expansion history of the universe. Future experiments promise to mine
this information, through the Sunyaev-Zeldovich effect with galaxy
clusters and with large catalogs of type-1a supernova which can be used
as standard candles. I will discuss the extent to which these data
sources may provide future constraints on dark energy and modified
gravity. In particular, the mean pairwise velocitystatistic is
especially promising because it likely is much less sensitive to
systematic errors than most other contemplated dark energy probes.
