Department of Physics & Astronomy
University of Pennsylvania

Experimental
Particle Physics
Seminars

Fall 2007 & Spring 2008

Faculty lounge: Tuesdays & Thursdays at 1:30pm (Directions)
Coffee & cookies afterwards in Faculty Lounge

Contact: Assistant Professor Evelyn Thomson

See also previous years, theory seminars and department colloquia


Tuesday 25 March 1:30pm
Dr. Vadim Rusu
Wilson Fellow at Fermi National Accelerator Laboratory
From Collisions to Publication: A Higgs Story (Slides pdf)
For more than 30 years the Standard Model of Particle Physics provided a solid framework for explaining the experimental observations of the last decades. A fundamental piece is missing and that is the origin of mass. Within the Standard Model, the mass of fundamental particles is given by their interaction with the Higgs field. The quanta of this field is the Higgs boson. The experimental observation of the Higgs particle is an essential part of our particle physics program and may provide us with clues about new physics beyond the realm of the Standard Model. I will show the experimental progress towards this goal at CDF, one of the two experiments at Tevatron, the world's largest collider currently in operation. The presentation will overview all aspects of this progress, from detector and data collection improvements to new analysis strategies.
Tuesday 1 April 1:30pm
Dr. Chris Neu
University of Pennsylvania
Measurement of W+b-jets at CDF (pdf)

Tuesday 15 April 1:30pm
Dr. Anadi Canepa
University of Pennsylvania
Tau leptons at CDF (pdf)
Tau leptons are unique in the Standard Model. Thanks to a large coupling to the Higgs boson, they might shed light on the electroweak symmetry breaking. Tau leptons are also an exciting window into New Physics. SUSY predicts abundance of taus in charged Higgs decays. Taus processes are enriched in Right-Left Symmetric Models with double charged Higgs, while new massive gauge bosons can undergo lepton flavor violating decays. CDF established its tau reconstruction technique measuring the W → τ ν and Z → τ+ τ- cross sections and it is now exploring the pp collisions at Tevatron looking for new phenomena. The challenge of reconstructing taus at hadron colliders and the latest results of tau physics at CDF are reported.
Thursday 17 April 4pm Room A8
Emeritus Professor James Cronin
University of Chicago
Study of the Highest Energy Cosmic Rays with the Pierre Auger Observatory
Tuesday 22 April 1:30pm
Professor Joe Boudreau
University of Pittsburgh
sin 2 βs at CDF
While CP violation in B0 and B+ decays has been extensively investigated at B-factories over the last decade, corresponding knowlege in the B0s system has been lacking. B0s mesons, which are not produced in B factories at the Upsilon(4S) are produced with large cross section at the Tevatron collider. Following the measurement of the B0s to B0s oscillation frequency in 2006, the CDF experiment has now investigated CP asymmetries in B0s meson decays. We report on the very first flavor-tagged analysis of about 2,000 B0s decays to J/ψ φ, reconstructed in 1.35/fb of data. This channel is sensitive not only to the width difference Delta Γ in the B0s system but also to to βs, the angle of the "squashed" (bs) unitarity triangle. We report a confidence region in the two dimensional space of 2βs and Delta Γ. The data is consistent with the standard model prediction at the 15% confidence level, corresponding to 1.5 Gaussian standard deviations.

Fall 2007


Tuesday 18 September A5 3:15pm
Dr. Bernd Stelzer
University of California, Los Angeles
Search for Single Top Quark Production at CDF
Slides (ppt) and pdf (no animations)
In 1995, the CDF and D0 collaborations at the Tevatron collider at Fermilab discovered top quarks that were produced in pairs via the strong interaction. The top quark was measured to be the heaviest elementary particle of the Standard Model. Ten years after the top quark discovery, many things remain unknown about its properties. In this talk, I will present recent evidence for electroweak single top quark production. This alternative mechanism of producing top quarks at the Tevatron is experimentally very challenging to measure but allows the direct determination of the CKM matrix element |Vtb|.
Wednesday 17 October A2 3:30pm
Dr. Ulrich Husemann
Yale University
Search for Flavor-Changing Neutral Currents in Top Quark Decay at CDF
Slides (pdf)
Flavor changing neutral current (FCNC) interactions are heavily suppressed in the standard model of particle physics, but are expected to be enhanced in the presence of new physics. Searches for FCNC interactions are therefore excellent probes of physics beyond the standard model. The suppression of FCNC interactions is especially strong in the top quark sector. The standard model predicts branching fractions for top quark FCNC decays far below the reach of experiments at the Fermilab Tevatron and even at the Large Hadron Collider currently under construction at CERN. I will present the first search for the FCNC decay t→ Zq during Tevatron Run II using data recorded with the CDF II detector between March 2002 and September 2006.
Tuesday 30 October A5 3:15pm
Prof. Daniel McKinsey
Yale University
New results from the XENON10 dark matter search
Slides (pdf)
The XENON10 experiment is a search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). The XENON10 detector uses the simultaneous measurement of ionization and scintillation in liquid xenon to distinguish between nuclear recoils (due to WIMPs or fast neutrons) and electron recoils (due to gamma rays). Ionization electrons are extracted into the xenon vapor where they produce a large proportional scintillation signal in a grid assembly. Both prompt and proportional scintillation light are detected by PMT arrays on the top and bottom of the active liquid xenon volume. The distribution of proportional scintillation light in the top PMT array can be used to achieve xy position resolution, while the ionization drift time gives position resolution in the z direction. This allows the definition of a low-background fiducial volume. XENON10 was installed in the underground Gran Sasso National Laboratory in Italy in March 2006, and a blind analysis was performed on data acquired between November 2006 and February 2007. I will present the results of that analysis, which has resulted in the most sensitive limit to date on the spin-independent WIMP-nucleon scattering cross-section. I will also describe LUX, a new dark matter experiment using the same technology, planned for 2008-2009.
Tuesday 13 November A5 3:15pm
Dr. Conor Henderson
Massachusetts Institute of Technology
Global Search for New Physics at CDF
Slides (pdf)
The Standard Model of particle physics is widely believed to be incomplete, but as yet there are no clear indications as to what form the new electroweak scale physics might take. Rather than focusing on particular new physics scenarios, we present a new approach where the entire high transverse momentum data collected by the CDF detector at the Fermilab Tevatron are searched for discrepancies relative to the Standard Model prediction. A model-independent approach (Vista) considers the bulk features of the data, and a quasi-model-independent technique (Sleuth) focuses on the high-pT tails. Results of this global search for beyond Standard Model physics will be presented.
Tuesday 27 November A5 3:15pm
Prof. B. Lee Roberts
Boston University
Proposal for a new muon g-2 experiment
Slides (pdf)
The muon (g-2) experiment at the BNL AGS reached a relative precision of 0.5 parts per million on the muon anomalous magnetic moment. Thanks to recent data from electron-positron annihilation to hadrons, the standard-model prediction has reached the same level of precision. When compared, the two differ by 3.4 standard deviations. Since the muon anomaly is sensitive to a wide range of physics beyond the standard model, agreement or difference with the standard-model will be important in constraining interpretations of discoveries that will be made at the LHC. The experiment and theory will be reviewed, and possibilities for improving both values will be discussed, along with the implications for LHC data.
A recent review of theory and experiment can be found in hep-ph/0703049, published in Reports on Progress in Physics, {\bf 70}, (2007) 795-881 The non-standard model reach is discussed in arXiv:0705.4617 [hep-ph]
Tuesday 11 December 2N36 1:30pm
Prof. Gregorio Bernardi
LPNHE, Universities Paris VI and VII, France
Search for the Higgs boson at D0
Slides (pdf)
The Higgs boson is the only particle of the standard model which has not been discovered yet, but it might be the most important one. Indeed, it is through the Higgs mechanism that all massive fundamental particles are expected to acquire their mass. Hence the search for the Higgs boson has been one of the major activities of Elementary Particle Physicists during this last decade. In this seminar, we will introduce the physics of the Higgs boson and report on the experimental searches which are currently being done at the Tevatron by the D0 experiment, and on the combined results obtained by CDF and D0. We will conclude on the prospects of Higgs discovery in the coming years.

Early spring 2008 seminars this link points to a password-protected web page.