News

Nuclear and Particle Physics Colloquium

Spring 2009

Every Monday
@4:15 pm
Room 26-414, Kolker Room

Refreshments @ 4:00pm

Basic principles of quantum mechanics and general relativity are used
to argue that a maximally spinning Kerr black hole with spin J has a
dual description as a two-dimensional conformal field theory (CFT)
with central charge c=12J/hbar. The Bekenstein-Hawking area law is
then explained by the statistical mechanics of the CFT. The observed GRS 1915+105, whose spin is more that 98% of the maximal
value, is dual to a CFT with c ~10^{79}.

Experiments at the Relativistic Heavy Ion Collider (RHIC) indicate that the quark gluon plasma is a very good fluid. Motivated by these results we study the question whether there is a fundamental limit to the " "perfectness'' of a fluid. We review arguments based on kinetic theory as well as string theory that suggest that there is lower bound for the ratio of shear viscosity to entropy density. We present an analysis of experimental results for the shear viscosity of the best quantum fluids that have been studied in the laboratory. This includes Bose fluids (such as liquid Helium), Fermi fluids (dilute atomic Fermi gases near a Feshbach resonance), and gauge theory plasmas (the QGP at RHIC).

The field of very high energy (VHE) astrophysics has developed rapidly during the last few years as a result of new instruments and exciting discoveries.
Ground-based telescopes, such as VERITAS in southern Arizona, have detected numerous astrophysical sources of TeV gamma rays, including
supernova remnants and active galaxies. These telescopes are also carrying out sensitive searches for the annihilation of neutralino dark
matter. We expect similar exciting results from the newly-launched Fermi Gamma-ray Space Telescope. This talk will review the status of the field and will outline the scientific prospects over the next few years.

Liquid Argon Time Projection Chambers are precision neutrino detectors which appear scalable to very large volumes. This combination makes them very promising detectors for long baseline neutrino oscillation physics. Their fine-grained tracking and total absorption calorimetry capabilities translate to sensitivity to neutrino oscillation physics significantly better than conventional detection techniques such as Water Cerenkov detectors. Recently, interest in these detectors in the US has grown, and a program to scale these detectors to the large sizes needed for long baseline physics has come into focus. This program, including the ArgoNeuT and MicroBooNE projects, will be described.

Abstract: I will describe the motivation and status of the Large Synoptic Survey Telescope (LSST), a project currently in the design stage that promises to usher in the era of cosmic cinematography by scanning the entire accessible sky every few days, to 24th magnitude. The LSST is being engineered to minimize potential sources of systematic error for precision photometry and weak lensing. The LSST will allow for unprecedented parallel science from a common image stream, for topics ranging from fundamental physics to a census of the solar system.

About 20 years ago non-relativistic QCD (NRQCD) emerged as an effective theory of quantum chromodynamics. Prior to this time the available theoretical calculations lead to ill-defined predictions for quarkonium processes. NRQCD resolved these problems and made precise and consistent predictions possible. In this talk I review the development and the applications of NRQCD, including the current polarization puzzle at hadron colliders. I also will discuss a modern version of NRQCD, known as vNRQCD, which gives an improved understanding of the internal dynamics of quarkonium systems, including methods to sum large logarithms and to systematically describe unstable particles. These features allow quarkonium systems to be used for precise measurements of QCD parameters such as the strong coupling and quark masses. As applications I discuss measurements of the bottom quark mass from current experimental data, and a method for measuring the top mass from the top pair threshold at a future lepton collider with an order of magnitude better precision than it is known today.

I will discuss the status of the standard model Higgs boson search. At
ICHEP 2008 in Philadelphia, the Fermilab Tevatron experiments made the
first advance since the CERN LEP experiments excluded a Higgs boson with
mass below 114 GeV in 2000. The new exclusion of a Higgs boson with mass of about 170 GeV at 95% confidence level is the result of a search for a Higgs boson decay to W+W- pair, using 3 fb-1 of data acquired since 2001. With an extra 1.5 fb-1 of data being delivered for each year that the
Tevatron continues to run, there is potential for significant improvement
in this physics result. Since the search for a Higgs boson with mass in
the range 114-130 GeV is particularly challenging for both the Tevatron
and the CERN LHC experiments, I will describe improvements to searches
here.

Lattice QCD is a well established tool for studying the low energy dynamics of QCD. Precise results with fully controlled uncertainties are available for many single hadron properties and lattice QCD has become a integral part of modern particle physics. In the last few years the first realistic calculations in the two hadron sector have also appeared (although not yet with the same level of systematic control of uncertainties as in the single hadron case) stimulating the interest of the nuclear physics community as well. To become a central part of nuclear physics, lattice QCD must confront the many hadron systems that define nuclear physics.

Recently, the first steps have been taken in this direction by the NPLQCD collaboration who have performed a series of numerically studies of systems of up to twelve pions and/or kaons. These investigations have allowed us to determine the low energy three-pion interaction for the first time, and are a first step towards many body physics from QCD. The ground state of these multi-pion/multi-kaon systems for large numbers of particles is a Bose-Einstein condensate.
In the interiors of neutron stars, the densities are such that it may be energetically favorable to neutralize system with such a condensate of negatively charged kaons rather than electrons, with significant consequences for the nuclear equation of state. Our numerical calculations have allowed us to address the physics of such systems, constraining relevant aspects of the equation of state. As one would expect, such a condensed state modifies the properties of other hadrons interacting with it and we have recently seen such a medium effect by measuring the screening of the potential between a static quark--anti-quark pair by a pion condensate.

I will discuss these recent results and more general aspects of many body lattice QCD.

The existence of dark matter has been confirmed by a wide variety of experiments, on a wide variety of length scales. However, the nature of the dark matter remains elusive. One intriguing class of candidates - weakly interacting massive particles of "WIMPS" - offer the prospect of detection in cosmic rays, in direct detection experiments, and at colliders. Of late, there has been as increasing set of experimental signal, principally from cosmic rays, which may be providing a first sign of dark matter. I will explore the range of signals and anomalies, and the challenges of understanding all of them in terms of dark matter. We will see that, if dark matter is responsible for these anomalies, it may be pointing us to a much richer set of physics in the dark sector.

First, derivation of the predicted number density of the cosmic
neutrino background (CNB) will be reviewed, and its role in the Hot Big-Bang Cosmology stressed. Next I will discuss the amount of possible density enhancement in galactic clusters of massive, and by now nonrelativistic, CNB neutrinos. The application of coherent scattering to the detection of CNB will be also reviewed, and its difficulties explained. Main part of the talk will be concerned with the detection of CNB using radioactive targets. While such approach is extremely difficult, one can envisage that it might eventually work provided the neutrino mass is sufficiently large, perhaps at least 0.1 eV.

"High-Energy Neutrino Astronomy: Towards a Kilometer-Scale Neutrino Observatory"

Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature produces photons and protons with energies in excess of one hundred and one hundred million Terraelectronvolts, respectively. The cosmic ray connection sets the scale of cosmic neutrino fluxes. The problem has been to develop a robust and affordable technology to build the kilometer-scale neutrino detectors required to do the science. The AMANDA telescope transforming ultra-clear deep Antarctic ice into a Cherenkov detector of muons and showers initiated by neutrinos of all three flavors, has met this challenge. Having collected more than 6000 well-reconstructed muon neutrinos of 50 GeV ~ 500 TeV energy, AMANDA represents a proof of concept for the ultimate kilometer-scale neutrino observatory, IceCube, now half complete and already producing results exceeding in sensitivity seven years of AMANDA data.



		Nuclear and Particle Physics Colloquium Spring 2009 Every Monday @4:15 pm Room 26-414, Kolker Room Refreshments @ 4:00pm February 2nd Registration Day February 9th Andy Strominger, Harvard University "The Kerr/CFT Correspondence: Holography in the Sky" Basic principles of quantum mechanics and general relativity are used to argue that a maximally spinning Kerr black hole with spin J has a dual description as a two-dimensional conformal field theory (CFT) with central charge c=12J/hbar. The Bekenstein-Hawking area law is then explained by the statistical mechanics of the CFT. The observed GRS 1915+105, whose spin is more that 98% of the maximal value, is dual to a CFT with c ~10^{79}. Host: Alan Guth February 16th President's Day Vacation February 23rd Thomas Schaefer, North Carolina State University "In Search of the Perfect Fluid" Experiments at the Relativistic Heavy Ion Collider (RHIC) indicate that the quark gluon plasma is a very good fluid. Motivated by these results we study the question whether there is a fundamental limit to the " "perfectness'' of a fluid. We review arguments based on kinetic theory as well as string theory that suggest that there is lower bound for the ratio of shear viscosity to entropy density. We present an analysis of experimental results for the shear viscosity of the best quantum fluids that have been studied in the laboratory. This includes Bose fluids (such as liquid Helium), Fermi fluids (dilute atomic Fermi gases near a Feshbach resonance), and gauge theory plasmas (the QGP at RHIC). Host: John Negele March 2nd Rene Ong, University of California, Los Angeles JOINT with Astro "Viewing the Universe at Very High Energies" The field of very high energy (VHE) astrophysics has developed rapidly during the last few years as a result of new instruments and exciting discoveries. Ground-based telescopes, such as VERITAS in southern Arizona, have detected numerous astrophysical sources of TeV gamma rays, including supernova remnants and active galaxies. These telescopes are also carrying out sensitive searches for the annihilation of neutralino dark matter. We expect similar exciting results from the newly-launched Fermi Gamma-ray Space Telescope. This talk will review the status of the field and will outline the scientific prospects over the next few years. Host: Gabriella Sciolla March 9th Bonnie Fleming, Yale "The US LArTPC program: ArgoNeuT, MicroBooNE, and Beyond Liquid Argon Time Projection Chambers are precision neutrino detectors which appear scalable to very large volumes. This combination makes them very promising detectors for long baseline neutrino oscillation physics. Their fine-grained tracking and total absorption calorimetry capabilities translate to sensitivity to neutrino oscillation physics significantly better than conventional detection techniques such as Water Cerenkov detectors. Recently, interest in these detectors in the US has grown, and a program to scale these detectors to the large sizes needed for long baseline physics has come into focus. This program, including the ArgoNeuT and MicroBooNE projects, will be described. Host: Joe Formaggio TUESDAY March 17th JOINT WITH ASTRO in the MARLAR LOUNGE Chris Stubbs, Harvard University "The Large Synoptic Survey Telescope: from Dark Energy to Killer Asteroids" Abstract: I will describe the motivation and status of the Large Synoptic Survey Telescope (LSST), a project currently in the design stage that promises to usher in the era of cosmic cinematography by scanning the entire accessible sky every few days, to 24th magnitude. The LSST is being engineered to minimize potential sources of systematic error for precision photometry and weak lensing. The LSST will allow for unprecedented parallel science from a common image stream, for topics ranging from fundamental physics to a census of the solar system. Host: Gabriella Sciolla March 23rd Spring Vacation March 30th Andre Hoang, Heisenberg Max Planck Institute "Non-Relativistic QCD and Precision Quarkonium Physics" About 20 years ago non-relativistic QCD (NRQCD) emerged as an effective theory of quantum chromodynamics. Prior to this time the available theoretical calculations lead to ill-defined predictions for quarkonium processes. NRQCD resolved these problems and made precise and consistent predictions possible. In this talk I review the development and the applications of NRQCD, including the current polarization puzzle at hadron colliders. I also will discuss a modern version of NRQCD, known as vNRQCD, which gives an improved understanding of the internal dynamics of quarkonium systems, including methods to sum large logarithms and to systematically describe unstable particles. These features allow quarkonium systems to be used for precise measurements of QCD parameters such as the strong coupling and quark masses. As applications I discuss measurements of the bottom quark mass from current experimental data, and a method for measuring the top mass from the top pair threshold at a future lepton collider with an order of magnitude better precision than it is known today. Host: Iain Stewart April 6th Evelyn Thomson, University of Pennsylvania "Search for the standard model Higgs boson at the Tevatron" I will discuss the status of the standard model Higgs boson search. At ICHEP 2008 in Philadelphia, the Fermilab Tevatron experiments made the first advance since the CERN LEP experiments excluded a Higgs boson with mass below 114 GeV in 2000. The new exclusion of a Higgs boson with mass of about 170 GeV at 95% confidence level is the result of a search for a Higgs boson decay to W+W- pair, using 3 fb-1 of data acquired since 2001. With an extra 1.5 fb-1 of data being delivered for each year that the Tevatron continues to run, there is potential for significant improvement in this physics result. Since the search for a Higgs boson with mass in the range 114-130 GeV is particularly challenging for both the Tevatron and the CERN LHC experiments, I will describe improvements to searches here. Host: Steve Nahn April 13th Will Detmold "Many body lattice QCD" Lattice QCD is a well established tool for studying the low energy dynamics of QCD. Precise results with fully controlled uncertainties are available for many single hadron properties and lattice QCD has become a integral part of modern particle physics. In the last few years the first realistic calculations in the two hadron sector have also appeared (although not yet with the same level of systematic control of uncertainties as in the single hadron case) stimulating the interest of the nuclear physics community as well. To become a central part of nuclear physics, lattice QCD must confront the many hadron systems that define nuclear physics. Recently, the first steps have been taken in this direction by the NPLQCD collaboration who have performed a series of numerically studies of systems of up to twelve pions and/or kaons. These investigations have allowed us to determine the low energy three-pion interaction for the first time, and are a first step towards many body physics from QCD. The ground state of these multi-pion/multi-kaon systems for large numbers of particles is a Bose-Einstein condensate. In the interiors of neutron stars, the densities are such that it may be energetically favorable to neutralize system with such a condensate of negatively charged kaons rather than electrons, with significant consequences for the nuclear equation of state. Our numerical calculations have allowed us to address the physics of such systems, constraining relevant aspects of the equation of state. As one would expect, such a condensed state modifies the properties of other hadrons interacting with it and we have recently seen such a medium effect by measuring the screening of the potential between a static quark--anti-quark pair by a pion condensate. I will discuss these recent results and more general aspects of many body lattice QCD. Host: John Negele April 20th Patriot's Day Vacation April 27th Neal Weiner, NYU Center for Cosmology and Particle Physics "Illuminating Dark Matter" The existence of dark matter has been confirmed by a wide variety of experiments, on a wide variety of length scales. However, the nature of the dark matter remains elusive. One intriguing class of candidates - weakly interacting massive particles of "WIMPS" - offer the prospect of detection in cosmic rays, in direct detection experiments, and at colliders. Of late, there has been as increasing set of experimental signal, principally from cosmic rays, which may be providing a first sign of dark matter. I will explore the range of signals and anomalies, and the challenges of understanding all of them in terms of dark matter. We will see that, if dark matter is responsible for these anomalies, it may be pointing us to a much richer set of physics in the dark sector. Host: Alan Guth May 4th Petr Vogel, Caltech "Detecting Cosmic Neutrino Background" First, derivation of the predicted number density of the cosmic neutrino background (CNB) will be reviewed, and its role in the Hot Big-Bang Cosmology stressed. Next I will discuss the amount of possible density enhancement in galactic clusters of massive, and by now nonrelativistic, CNB neutrinos. The application of coherent scattering to the detection of CNB will be also reviewed, and its difficulties explained. Main part of the talk will be concerned with the detection of CNB using radioactive targets. While such approach is extremely difficult, one can envisage that it might eventually work provided the neutrino mass is sufficiently large, perhaps at least 0.1 eV. Host: Peter Fisher May 11th Francis Halzen, University of Wisconsin at Madison "High-Energy Neutrino Astronomy: Towards a Kilometer-Scale Neutrino Observatory" Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature produces photons and protons with energies in excess of one hundred and one hundred million Terraelectronvolts, respectively. The cosmic ray connection sets the scale of cosmic neutrino fluxes. The problem has been to develop a robust and affordable technology to build the kilometer-scale neutrino detectors required to do the science. The AMANDA telescope transforming ultra-clear deep Antarctic ice into a Cherenkov detector of muons and showers initiated by neutrinos of all three flavors, has met this challenge. Having collected more than 6000 well-reconstructed muon neutrinos of 50 GeV ~ 500 TeV energy, AMANDA represents a proof of concept for the ultimate kilometer-scale neutrino observatory, IceCube, now half complete and already producing results exceeding in sensitivity seven years of AMANDA data. May 18th Finals Week Committee Members: Gabriella Sciolla (Chair) Joseph Formaggio Steve Nahn John Negele Alan Guth
updated 4/14/09