Universite de Geneve
Ecole de physique - Département de physique nucléaire et corspusculaire
24, Quai Ernest-Ansermet
1211 GENEVE 4
Tél: (022) 379 62 73 - Fax: (022) 379 69 92
Wednesday 30 January 2008
PARTICLE PHYSICS SEMINAR
at 17:00 – Stückelberg Auditorium
EXOPLANETS AND QUARKS
Prof. Philip Yock, Department of Physics, University of Auckland, Auckland, New Zealand
The search for Earth-like extra-solar planets is one of the forefront areas of astronomy today. The NZ/Japan MOA collaboration uses the gravitational microlensing technique at high magnification. When the magnification exceeds 50, Earth-mass planets orbiting the lens star at distances ~ 2-3 AU are detectable. Twenty-eight events with magnification > 50 were found by MOA in 2007. These will be briefly reviewed, together with earlier events in which planets were detected, and one in which the shape of a star was measured.
The mathematics of gravitational microlensing is comparable to that of Rutherford scattering, which underpins current research in particle physics. Recent data from CERN on hadron production in γ-γ interactions exceed the predictions of QCD by an order of magnitude at high pT. The amplitude for the process is asymptotically proportional to the sum of the squares of the charges of quarks. The data appear reminiscent of Rutherford’s old results, and suggestive of pre-QCD models where quarks had unit charges, or larger. Unequivocal tests could be made with the proposed International Linear Collider, but a plasma wakefield e-e- collider could provide the most affordable option.»
Information: http://dpnc.unige.ch/seminaire/annonce.html
Organizer : J.-S. Graulich