NPAC (Nuclear/Particle/Astro/Cosmo) Forum

MINOS (Main Injector Neutrino Oscillation Search) is a
mature neutrino experiment that has been accumulating data using the NuMI neutrino beam since 2005. Data from 7 x 1020 protons-on-target have been recorded, primarily in low-energy neutrino mode. An update on the charge-current analysis will be presented as well as the recent electron appearance result. Additional results will be briefly reviewed along with prospects for future running in anti-neutrino mode.
Host: 
Karsten Heeger
Speaker: Christopher White Illinois Institute of Technology

 

Available Downloads:

Room and Building: 
5280 Chamberlin
An enormous effort has been made to understand and model the nuclear force. The next step is to apply those models in an environment where three (or four) nucleons interact with each other and thoroughly test underlying assumptions of nuclear physics.

Traditionally three-nucleon calculations are carried out by solving Faddeev equations in a partial wave truncated basis, working either in momentum or coordinate space. We solve them directly as function of vector variables. The key advantage of our approach lies in its applicability at higher energies, where special relativity is expected to become relevant. We investigate relativistic three-boson scattering in the framework of Poincare invariant quantum mechanics. The main point here is the construction of unitary irreducible representations of the Poincare group, both for noninteracting and interacting particles. For three-body scattering the Faddeev scheme is reformulated relativistically.

Comparison of scattering observables obtained from relativistic and non-relativistic calculations based on simple Yukawa-type interactions lead to observations that should be relevant for more sophisticated interactions. These comparisons do not involve taking non-relativistic limits. Instead relativistic and non-relativistic three-body calculations are compared that contain interactions fitted to the same two-body data. All of the observed differences result form the different ways in which the two-body dynamics appears in the three-body problem.
Host: 
Baha Balantekin
Speaker: Charlotte Elster Ohio University, Athens

 

Available Downloads:

Room and Building: 
4274 Chamberlin

Joint HEP Seminar/NPAC Forum

Host: 
Karsten Heeger
Speaker: Kevin Lesko Lawrence Berkeley National Laboratory

 

Available Downloads:

Room and Building: 
4274 Chamberlin
We propose an inflationary scenario, M-flation, in which inflation is driven by three NXN Hermitian matrices Phi_i, i=1,2,3. The inflationary potential of our model in the most general form involves a commutator squared term, a cubic term involving product of a commutator with the field and a quadratic ``mass'' term. This class of potentials are strongly motivated by string theory. We show that one can consistently restrict the classical dynamics to a sector in which the Phi_i are proportional to the NXN irreducible representation of SU(2). In this sector our model effectively behaves as an N-flation with order N^2 number of fields, and therefore remove the fine-tunings associated with super-Planckian field and/or unnaturally small couplings in the chaotic type inflationry scenarios. Due to the matrix nature of the scalars 3N^2-1$ other scalar fields also affect the inflationary dynamics. These have the observational effects such as production of entropy (non-adiabatic) perturbations on cosmic microwave background. Moreover, the existence of these other scalars provides us with a natural preheating model for our setup.<br>
Host: 
Dan Chung
Speaker: Amjad Ashoorioon University of Michigan

 

Available Downloads:

Room and Building: 
4274 Chamberlin
Host: 
Stefan Westerhoff
Speaker: Segev BenZvi University of Wisconsin - Madison

 

Available Downloads:

Room and Building: 
4274 Chamberlin
In July 2008, the International X-ray Observatory (IXO) was announced to the > astronomical community. IXO is a joint mission with participation from ESA, NASA and JAXA, superseding the US Constellation-X mission concept. IXO is dedicated to high resolution X-ray spectroscopy, with 100 times the throughput for high resolution spectroscopy of previous X-ray missions. The baseline for IXO features a single large X-ray mirror and an extensible optical bench with a 20-25m focal length and moveable focal plane. The instruments include an X-ray wide field imaging spectrometer, a high spectral resolution non-dispersive X-ray spectrometer, an X-ray grating spectrometer, a hard X-ray imaginer and an X-ray polarimeter.

I will discuss the IXO science objectives and how it will help answer the following questions: How do super-massive Black Holes grow and evolve? Does matter orbiting close to a Black Hole event horizon follow the predictions of General Relativity? What is the Equation of State of matter in Neutron Stars? How does Cosmic Feedback work and influence galaxy formation? How does galaxy cluster evolution constrain the nature of Dark Matter and Dark Energy? Where are the missing baryons in the nearby Universe? When and how were the
elements created and dispersed? How do high energy processes affect planetary formation and habitability? How do magnetic fields shape stellar exteriors and the surrounding environment? How are particles accelerated to extreme energies producing shocks, jets, and cosmic rays?
Host: 
Dan McCammon
Speaker: Randall Smith Harvard Smithsonian Center for Astrophysics

 

Available Downloads:

Room and Building: 
4274 Chamberlin
The origin of flavor is one of the biggest mysteries of the Standard Model. Despite more than a half-century of data, we still have essentially no explanation for family replication in the Standard Model. Many theoretical models can incorporate or accommodate this replication, but very few actually explain/predict/require it. In this talk, I will describe some recent work on a possible new approach towards explaining the origin of family replication in the Standard Model.
Host: 
Sky Bauman and Lisa Everett
Speaker: Keith Dienes University of Arizona

 

Available Downloads:

Room and Building: 
4274 Chamberlin

Particles near $10^{20}$ eV are the most energetic particles known to us in the universe, also called ultra high energy cosmic rays. Their observations have led us to build the largest detector systems in the world, in the South the Auger air-shower array, and in the North the Telescope Array, and perhaps soon Auger-North. With these and earlier arrays events have been detected of an energy up to $3 , 10^{20}$ eV, which is a macroscopic energy. There have been two predictions: one that due to interaction with the microwave background the spectrum should show a turnoff near $5 , 10^{19}$ eV; a turn-off has been confirmed by two experiments, HiRes and Auger. Second, that active galactic nuclei, possibly radio galaxies, should be the accelerators, based on the non-thermal optical spectra of knots and hot spots in radio galaxies; this is now tentatively confirmed by Auger, but contradicted by HiRes. I will go through some fundamental problems with the predictions, which teach us about active galactic nuclei and starburst galaxies. Apart from differentiating various remaining options, such as gamma ray bursts, how to generate these particles, and their source population, there is one major difficulty: the lack of understanding of the cosmological web of magnetic fields, which may influence the propagation of high energy particles; here it is especially important to understand the role of our local cosmic neighborhood and a possible galactic magnetic wind. It appears from MHD simulations that magnetic scattering leads to a steep distribution function of scattering angles of the deviation from a straight line path for the arriving particles, and also to a substantial delay time distribution. I will list and debate the merits of the closest candidate sources, Cen A, Vir A and For A. I will discuss the observational and theoretical limits for an exemplary set of models, the predictions like chemical abundances, that result from these models, and how present and future observations will test our conclusions, especially with the the Auger Array, the Telescope Array (TA), the neutrino observatory IceCube, the TeV Cherenkov $gamma$-ray telescopes, and the future space observatory EUSO. We face a number of exciting challenges for plasma physics, particle physics, cosmology, astronomy, and may attain better tools for our deep understanding of matter.

Host: 
Stefan Westerhoff
Speaker: Peter L. Biermann MPI Bonn

 

Available Downloads:

Room and Building: 
4274 Chamberlin
In June 2007, MiniBooNE published results for a search for electron flavor neutrinos appearing in a predominantly muon neutrino beam. Although no excess of events was observed at an L/E consistent with a simple mixing interpretation of LSND, a > 3 sigma excess was observed at low energy. In the intervening time, MiniBooNE has acquired 3.3e20 POT delivered with the horn-focusing positively charged pions to create a predominantly antineutrino beam. The results from the recently unblinded nuebar appearance search will be discussed along with work that has transpired over the last year in understanding the low energy excess.
Host: 
Karsten Heeger & Mat Herndon
Speaker: Chris Polly University of Illinois Urbana-Champaign

 

Available Downloads:

Room and Building: 
4274 Chamberlin
I will present ongoing work to incorporate the effects of very high excitation states of atomic hydrogen on the recombination history of the universe. After a review of recombination, I will discuss the relevance of cosmological recombination for CMB observables, our approach to the high-n problem, and preliminary results.&lt;br&gt;<br>
Host: 
Daniel Chung
Speaker: Daniel Grin Caltech

 

Available Downloads:

Room and Building: 
4274 Chamberlin

Pages

©2013 Board of Regents of the University of Wisconsin System