CLASSE: LEPP Journal Club

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LEPP Journal Club

Fall 2006

Date Speaker  Institution Title & Abstract Files
08/11/2006 Katherine Copic University of Michigan "A new measurement of the ratio of W and Z production at CDF" Not available
08/18/2006 None No Journal Club
08/25/2006 Richard Kass Ohio State University "Recent Results on the CKM Angles Alpha and Beta"
The CKM matrix provides a description of CP violation in the standard model. Experiments (BABAR and Belle) at the B-factories are testing the validity of this approach to CP violation using B-mesons. In this presentation I will describe the current status of two of the three CKM phases, alpha (phi2) and beta (phi1), used to describe CP violation in B-meson decay. Recent results from BABAR will be highlighted.
09/01/2006 None Labor Day
09/08/2006 Chris Tully Princeton University "Jets and Missing Transverse Energy at CMS"
Introduction to jet reconstruction and hadron calorimetry specific to the preparation for LHC physics with the CMS detector. Highlighted will be some of the general physics concerns and detector techniques that impact the use of jets and transverse missing energy for first physics at the LHC.
09/15/2006 None CLEO Meeting
09/22/2006 Peter Wittich Cornell University "Like Sign Dilepton Search in CDF"
We describe a search for New Physics in 1 fb-1 of CDF Run II data, using a sample of two identified leptons of the same charge ("like-sign dileptons") This search is sensitive to New Physics with three or more leptons, such as SUSY trilepton signatures, or signals with Majorana particles, such as ~q~g signatures with decays into leptons.
09/29/2006 Yuri Orlov Cornell University "Electric dipole moments of the deuteron, proton, et al.: their meaning and possible measurement"
We discuss particles' intrinsic electric dipole moments (edm) violating P- and T-symmetries; the corresponding predictions of the Standard Model (SM) and SUSY; and the importance of measuring these edm's for testing physics beyond the SM. We then describe a new concept for measuring the edm's of deuterons, protons, and perhaps other nuclei in a small storage ring using a specially designed spin resonance caused by the presence of edm. We also describe the corresponding tools for supressing systematic errors.
10/06/2006 Mark Palmer Cornell University CESR Test Accelerator Plans
10/13/2006 Morris Swartz Johns Hopkins University "Physics of Charge Collection in Silicon Detectors at LHC"
We show that doubly peaked electric fields are necessary to describe grazing-angle charge collection measurements of irradiated silicon pixel sensors. A model of irradiated silicon based upon two defect levels with opposite charge states and the trapping of charge carriers can be tuned to produce a good description of the measured charge collection profiles in the fluence range (0.5 -5.0)x10^{14} n_{eq}/cm^2. The model correctly predicts the variation in the profiles as the temperature is changed from -10C to -25C. The measured charge collection profiles are inconsistent with the linearly-varying electric fields predicted by the usual description based upon a uniform effective doping density. This observation calls into question the practice of using effective doping densities to characterize irradiated silicon. The model is also being used to drive an improved hit reconstruction algorithm for the CMS Pixel Tracker. The new algorithm improves the resolution of longer pixel clusters (eta > 1.0) by 20-40% before irradiation and it improves all clusters after irradiation.
10/23/2006 (Special JC at 2:30 PM Monday) Daniel Sherman Harvard University "Top Production at the Tevatron"
The top quark, the most massive particle in the Standard Model, was discovered only ten years ago at the Tevatron collider at Fermilab. Now, as our analysis tools improve and statistical limitations begin to disappear, we have reached a new level of precision in the determination of top's properties. I will describe some of these recent developments in top physics, focusing on a measurement of the top pair production cross section at CDF in events with exactly one final-state lepton, the world's single best cross section measurement to date.
10/27/2006 Marco Battaglia LBL CANCELLED
11/03/2006 Jim Beatty Ohio State University "Cosmic Rays and Neutrinos at GZK Energies"
11/06/2006 at 2:00PM (SPECIAL) Jovan Mitrevski Columbia U "Search for Electroweak Top Quark Production at D0"
Electroweak productionof the top quark has many interesting and useful properties. One is that the cross section is proportional to | Vtb|^2 and thus provides a test of the CKM matrix's 3-generation unitarity. Another is that it provides a way to probe the V - A structure of the weak interaction, which causes the top quark to be highly polarized. Because the top quark decays before it has time to hadronize, it retains its polarization information, making it available for study. Furthermore, due to the large top mass, close to the scale of electroweak symmetry breaking, single top production is a good place to look for physics beyond the Standard Model. In this seminar I will discuss the search for electroweak production of the top quark being undertaken by the D0 collaboration at Fermilab. I will discuss our selection criteria and background modeling, and I will focus in particular on the matrix element method analysis currently under way using the 1 fb-1 data set.
11/10/2006 Karl Van Bibber LLNL "Ultrasensitive searches for the axion"
The axion is a hypothetical light pseudoscalar arising from our best solution to the Strong-CP problem, namely why the neutron has a vanishingly small electric dipole moment. A sufficiently light axion would also have been produced abundantly during the Big Bang, and thus it might solve another prime question in science today, namely what constitutes the dark matter of the Universe? So far however, due to its very light mass and extraordinarily small couplings to anything, it has defied both discovery or exclusion for three decades. Nevertheless, there is at present a renaissance of interest in the axion both theoretically and experimentally. Elegant and extremely sensitive experiments are ongoing around the world, on three fronts: searching for axions constituting the dark matter of our Milky Way halo, axions emitted in the Sun's burning core, and purely laboratory searches. All of the most sensitive experiments are based on the Primakoff effect, i.e. axion-photon mixing in a strong magnetic field.
11/17/2006 Ted Baltz Stanford University "Dark Matter Studies at Colliders and in the Galaxy"
The nature of the cosmic dark matter is one of the great mysteries in physics today. The best known candidate is the neutralino, the lightest superpartner in supersymmetric extensions of the Standard Model. We investigate the ability of the Large Hadron Collider (LHC) and the proposed International Linear Collider (ILC) to measure the astrophysically interesting properties of this dark matter candidate: the relic density, direct detection cross sections, and annihilation cross sections and branching ratios. We illustrate how astrophysical measurements dependent on these quantities contribute to collider studies of the microphysics of dark matter. The collider measurements of cross sections can contribute to astrophysics as well, allowing us to map the distribution of dark matter in our galaxy and in the universe. The GLAST gamma-ray satellite to be launched in 2007 may be able to make exactly such a map.
12/01/2006 Andy Albrecht UC Davis "Dark Energy"
The cosmic acceleration is widely regarded as one of the most exciting recent scientific developments. Many expect the radical changes to our understanding of fundamental physics will be required to understand the mystery of the cosmic acceleration (supposedly driven by the "Dark Energy"). Interestingly, new experiments are within reach that could have a tremendous impact on this very data-driven field. In this talk I will review some of the key theoretical issues and then discuss some of the opportunities presented by future experiments. The latter discussion will include some results from the recent Report of the Dark Energy Task Force (DETF) as well as newer work that extend the DETF results in interesting ways.
12/15/2006 Tom Shutt Case Western New techniques for Dark Matter detection