Organizers: Ashutosh Kotwal and Kate Scholberg

Duke Physics Room 246
(Unless otherwise noted)

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September 14: Abaz Kryemadhi, Indiana University, 12:00-1:00pm

Tests of CPT & Lorentz Violation with FOCUS Detector and Lifetime Measurement of Lambda_b via the exclusive decay Lambda_b ->J/psi Lambda with D0 Detector.

Abstract

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November 4: Jennifer Raaf, University of Cincinnati, 11:30 am-12:30 pm

MiniBooNE

The Mini Booster Neutrino Experiment at Fermilab (MiniBooNE) will confirm or refute the existence of the neutrino oscillation signal seen by the Liquid Scintillator Neutrino Detector (LSND) Experiment at Los Alamos National Laboratory. The experiment will search for the appearance of electron neutrinos in a beam of muon neutrinos. In addition to the oscillation search, non-oscillation physics analyses are also underway, making full use of our intense low energy neutrino beam. In particular, the neutral current pi-zero analysis will be discussed with prospects for future anti-neutrino running.

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January 17: Abjihit Majumder , LBNL, 12:00-1:00 pm

Two hadron correlations at high P_t in e+e-, deep-inelastic scattering and heavy-ion collisions

Correlations between two hadrons in a jet and their modification due to the jet traversing a dense medium are systematically studied within the generalised factorization and higher twist formalism of perturbative QCD. Under the collinear factorization approximation and facilitated by the cut-vertex technique, the two hadron inclusive cross section at leading order (LO) in e+e- annihilation is shown to factorize into a short distance parton cross section and a long distance dihadron fragmentation function. The DGLAP evolution of the dihadron fragmentation function is derived and includes a new contribution consisting of two independent fragmentations. Modifications to the dihadron fragmentation function from higher twist corrections in DIS off nuclei are computed. Such modifications arise from the multiple scattering of the struck quark off the soft gluons in a large nucleus and due to energy loss encountered in the radiation of a gluon. Such modifications also include the LPM effect. Comparisons with the data from the HERMES experiment are presented. This formalism is then generalized to include modifications in a hot and dense matter created in a heavy-ion collision. Comparisons with the data from the STAR experiment will be presented.

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February 7: Gianpaolo Carosi, MIT, 1:00-2:00 pm

Searches for Dark Matter with the AMS Experiment

AMS-01 was a cosmic ray detector that flew on the Space Shuttle in 1998 and was a precursor experiment for the much more advanced AMS-02 detector, currently under construction and scheduled to fly on the International Space Station in 2008. In this talk I will discuss the layout of these experiments and their general missions before focusing on their sensitivity to the search for signatures of dark matter.

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February 14: Laura Mersini, UNC, 1:00-2:00 pm

First Glimpse of New Physics in the Sky?

We propose a new method for identifying new physics imprints on present observational data in cosmology whereby signatures of string theory are clearly distinguished from imprints of possible features on the inflaton potential. Our method relies on the cross-correlations spectra of cosmic shear from large scale structure (LSS) with the CMB temperature anisotropies and E-mode polarization. Discrepancies in the source terms of cross-correlations provide the evidence for new physics because of the following properties: - inflationary cosmology provides only one source term (a.k.a primordial spectrum) for seeding all CMB spectra and LSS; - but string theory can add new non-inflationary channels to the source of perturbations or clustering at large scales. Models of single-field inflation with a feature, are disfavored even with present data. Upcoming WMAP results and future data from weak lensing of LSS will further improve our ability to probe new physics with this method and could open the first direct window to string theory.

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February 21: Chris Walter, Duke, 12:00-1:00 pm

Super-K, K2K and T2K: The Present and Future

In this talk I will review the latest atmospheric neutrino oscillation results from the Super-Kamiokande experiment, and also the latest results from the K2K long-baseline neutrino oscillation experiment. I will discuss the compatibility of the neutrino mixing parameters determined in the two experiments. Finally, I will address remaining open questions in neutrino oscillation physics, and the techniques we will use to address them in the next-generation T2K long-baseline experiment.

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February 28: John Beacom, Ohio State, 12:00-1:00 pm

The Diffuse Supernova Neutrino Flux

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March 28: Haiyan Gao, Duke, 1:00-2:00 pm

A New Search on Neutron Electric Dipole Moment

Recently, a new experiment was proposed to search for the neutron Electric Dipole Moment (EDM) with an unprecedented sensitivity. The proposed search will have a two orders of magnitude improvement over the current neutron EDM limit given by the Particle Data Group. A search for a non-zero value of the neutron EDM is a direct search of the time reversal symmetry (T) violation. Therefore, it provides a unique insight of CP violation because of the CPT theorem. The Standard Model (SM) prediction for the neutron EDM is below the current experimental EDM limit by six orders of magnitude. However, many proposed models of electroweak interaction which are extensions beyond the SM predict much larger values of neutron EDM. The new experiment has the potential to reduce the acceptable range of predictions by two orders of magnitude. Furthermore, if new sources of CP violation are present in nature beyond the CKM (after Cabibbo, Kobayashi, and Maskawa) mechanism in the Standard Model and are relevant to hadronic systems, this experiment offers an unique opportunity to measure a non-zero value of neutron EDM. The current understanding of the baryogenesis suggests that other sources of CP violation might exist in nature beyond the Standard Model and beyond what have been observed so far. To explain the baryon number asymmetry in the universe through the grand unified theory or electroweak baryogenesis, substantial New Physics in the CP violation sector is required. In this talk, I will discuss this new experiment following a brief review of previous neutron EDM experiments.

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April 4: Daniel Cronin-Hennessy, U. of Minnesota, 1:00-2:00 pm

CLEO-c: A New Frontier of Weak and Strong Interactions

The Cornell Electron-positron Storage Ring (CESR) has recently completed an upgrade that alllows high luminosity e+e- collisions in the charm threshold region. I will overview the goals of the CLEO-c collaboration and report the earliest results from the CLEO-c experiment which are derived from CLEO-c pilot dataset.

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April 11: Harald Griesshammer, TU München, 1:00-2:00 pm

Nucleon Polarisabilities from Compton Scattering off the Proton and Deuteron

Joint HEP/TNT/TUNL seminar

I show that Chiral Effective Field Theory for photon energies up to $200$ MeV is the tool to accurately determine the proton and neutron spin-independent and spin-dependent polarisabilities from Compton scattering experiments. A multipole analysis of the amplitudes reveals the dispersive effects from the internal degrees of freedom of the nucleon: Whereas pion degrees of freedom suffice to describe data at $70$ MeV, the energy- and angular dependence of the nucleon polarisabilities induced by the $\Delta(1232)$ is mandatory for good agreement at higher energies. It proves in particular indispensable to understand deuteron Compton scattering at $95$ MeV as measured at SAL. Predicting this energy-dependence by Chiral Perturbation Theory with the $\Delta$ as explicit degree of freedom, the proton and neutron polarisabilities are extracted with previously unknown accuracy. They are identical within the accuracy of available data. We propose to extract the thus far ill-determined spin-dependent polarisabilities from asymmetry-experiments in a model-independent way, and present predictions.

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April 18: Masafumi Koike, Virginia Tech, 12:00-1:00 pm

Muon-electron conversion in nuclei

The coherent muon-electron conversion rates in various nuclei are calculated for general lepton flavor violating (LFV) interactions. For any types of operators, the results of our calculation indicate a tendency that the conversion branching ratio is larger for the nuclei with moderate atomic numbers than that for light or heavy nuclei. Although the tendency is the same, there are differences in atomic number dependences of the conversion rate for various LFV couplings. The experiments in various nuclei are therefore useful for model discrimination because each theoretical model predicts different atomic number dependences.

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April 25: Jon Engel, UNC, 12:00-1:00 pm

Time-reversal violation and atomic electric dipole moments

The Standard Model violates time-reversal invariance, but apparently not strongly enough to account for the baryon asymmetry in the universe. One of the best ways to search for other sources of time-reversal violation is to measure electric dipole moments of atoms. After discussing why, I show that the best atoms to use are those with asymmetrically shaped nuclei, and describe a calculation of the collective enhancement of time-reversal violation in one such nucleus, 225Ra. All other things being equal, an experiment in 225Ra --- and one is currently being prepared --- will be much more sensitive than the best experiment at present (which uses an 199Hg).

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UNC HEP-related seminars