Indiana University High Energy Physics

and Astrophysics Seminars

2007-2008 Academic Year
 

Mondays, 4pm  Refreshments 3:30 pm
Swain West 238

Contact: Mike Berger and Mark Messier
 


 

Spring Semester 2008
 
 
 

 
 
 
Jan. 7: The Quest for the Higgs
Sabine Lammers
Columbia University


 

 
 
 
Jan. 14:


 

 
 
 
Jan. 21:


 

 
 
 
Jan. 28: How fermions work: new interactions from the anomalous behavior of quarks, leptons and gauge fields
Richard Hill
Fermilab

"Anomalies" are a peculiar feature of interacting fermions and gauge fields, for instance in the Standard Model, and they lead to surprising predictions. For example, quantum mechanical consistency enforces nontrivial relations between the electric charges of quarks and leptons. The well-predicted decay of the neutral pion into two photons was an important early clue leading to QCD, the modern theory of the strong interactions. I describe new applications of this phenomenon, including neutrino interactions and QCD vector meson decays in the Standard Model; and probes of electroweak symmetry breaking beyond the Standard Model.


 

 
 
 
Feb. 4: Quantum Chromodynamics at high energies and high densities
Anna Stasto
Penn State U.

One of the most intruiging subjects in the theory of strong interactions is the high-energy limit of QCD. Since many years there have been intensive studies on the relation between Regge theory and QCD. The so - called BFKL (Balitskii- Fadin-Kuraev-Lipatov) equation is the result of the perturbative resummation in QCD that simulates the effect of the Pomeron exchange within the field theory. Unfortunately, the subleading corrections turned to be very large which questioned the stability of the expansion and the applicability of the whole approach. In this talk I discuss the high energy limit and show that the after a resummation which involves important phase space effects the result for the QCD Pomeron is much more stable and compatible with the experimental data. I show phenomenological applications for the neutrino physics and deep inelastic scattering at HERA. I also show that in the high energy limit opens up a new regime with very high density of partons. I discuss techniques which involve nonlinear evolution equation for the gluon density that aim at a description of this regime. Finally, I discuss the possible future directions in this field.


 

 
 
 
Feb. 7:
Thursday 		Many-body systems in QCD
Will Detmold
U. Washington

Multi-hadron systems are of great interest in many areas of physics, from low energy scattering experiments to neutron stars. In this seminar, I will discuss such systems from the point of view of lattice QCD. While QCD calculations of single hadron properties are at a relatively mature stage, multi-hadron states are only beginning to be explored. I will describe recent progress in calculations of systems of up to twelve mesons. These calculations have allowed us to determine both the two- and three- body interactions between pions and kaons for the first time.


 

 
 
 
Feb. 11: Testing the Standard Model with Lattice QCD
Ruth Van de Water
Fermilab

Recent advances in both computers and algorithms now allow realistic calculations of Quantum Chromodynamics (QCD) interactions using the numerical technique of lattice QCD. The methods used in ``2+1 flavor" lattice calculations have been verified both by post-dictions of quantities that were already experimentally well-known and by predictions that occurred before the relevant experimental determinations were sufficiently precise. This suggests that the sources of systematic error in lattice calculations are under control, and that lattice QCD can now be reliably used to calculate those weak matrix elements that cannot be measured experimentally but are necessary to interpret the results of many high-energy physics experiments such as those at SLAC, KEK, and Cornell. These same calculations also allow stringent tests of the Standard Model of particle physics, and may therefore lead to the discovery of new physics in the future. As an example, I discuss a calculation-in-progress of the neutral kaon bag parameter. I also briefly discuss the future role of lattice gauge theory in particle physics, in particular during the era of the LHC.


 

 
 
 
Feb. 18: Supersymmetric Grand Unification, LEP puzzle and the Higgs boson at the LHC
Radovan Dermisek
Princeton, Inst. Advanced Study

The Large Hadron Collider (LHC) will start colliding protons at unprecedented energy this year. The purpose is to learn about physics behind electroweak symmetry breaking and discover the last missing piece of the Standard Model of elementary particle physics, the Higgs boson. The Standard Model is a very successful theory that describes three of the four known fundamental interactions between the elementary particles and has many predictions that were experimentally confirmed at the Large Electron-Positron casting a shadow on the whole idea of supersymmetric grand unification. I will describe a simple way of reconciling the prediction of supersymmetry for the mass of the Higgs boson, precision EW data and the negative LEP result in models where the Higgs boson decays in a different way than it does in the standard model. This proposal dramatically changes the prospect for discovery of the Higgs boson at the LHC.


 

 
 
 
Feb. 25:


 

 
 
 
Feb. 28:
Thursday		 The Nuclear and Many-Body Physics of the Neutron Star Crust
Andrew Steiner
Michigan State

The neutron star crust, the 1 kilometer region on the surface composed of nuclei and superfluid neutrons, is the physical location of the majority of the phenomena observed in neutron stars. The nucleon-nucleon interaction and the transport properties of complicated hadronic matter play a significant role in determining the basic properties of matter in the crust. I present the first self-consistent model of the neutron star crust and show that the composition depends critically on the nuclear symmetry energy. Also, X-ray superbursts are strongly dependent on the neutrino emissivity from the breaking and reformation of Cooper pairs in the neutron superfluid. In the second part of this talk, I show why previous computations of this emissivity were incorrect, and delineate the cases where the vector response is comparable to the axial response.


 

 
 
 
Mar. 3: Gauge/gravity duality and supersymmetric states
Oleg Lunin
U. Chicago

Two of the most important open problems in theoretical physics are a construction of a consistent theory of quantum gravity and an analytic understanding of strongly coupled gauge theories. These two problems are unified in the context of gauge/string duality, which states that gravity and field theory give complementary descriptions of the same physics. I will review the basic ideas of the AdS/CFT correspondence with a particular emphasis on the gravity description of heavy states in field theory. I will show that such states correspond to regular geometries, and, unlike the familiar metrics appearing in general relativity, these geometries do not have sources. I will discuss how to use these metrics to learn about field theory and black holes.


 

 
 
 
Mar. 10: SPRING BREAK


 

 
 
 
Mar. 17:


 

 
 
 
Mar. 24:


 

 
 
 
Mar. 31: Light charged Higgs at the beginning of the LHC era
Enrico Lunghi
Fermilab

I review the experimental evidence and theoretical biases that point to physics beyond the Standard Model. In the context of realistic supersymmetric models, I will investigate whether existing experimental constraints still allow for a light extended Higgs sector. Predictions at LHC in such scenarios are explored.


 

 
 
 
Apr. 7: Holographic Cold Dense Baryons
Greg van Anders
University of British Columbia

This talk will describe work in progress that aims to understand cold dense systems of baryons in strongly coupled gauge theories with a large number of colors. We will explain how these systems are constructed using holographic techniques, and what can be learned by studying them. In particular we will discuss a proposed holographic description of a Fermi surface.


 

 
 
 
Apr. 14: HERA and the ZEUS experiment
Rik Yoshida
Argonne

The ZEUS experiment at HERA concluded its data taking in 2007 after 16 years of operation. I will cover some of the highlights from the experiment, concentrating mainly on the proton structure function results.


 

 
 
 
Apr. 21: