Research Interests
My current research is devoted to uncovering the properties of the
top quark, one of the fundamental building blocks of matter which
holds a prominent role in the Standard Model of particle physics. As a
member of the UCLA
Hadron Collider research group I collaborate with with my faculty
colleagues Jay
Hauser and
David Saltzberg and my postdoc Florencia Canelli and Ph.D. student Peter Dong on the
CDF experiment, a recently upgraded detector at the Tevatron collider
at Fermilab. This collider, currently in its second data taking period called Run II,
will
define the high energy frontier for at least the next 5 years,
offering exciting possibilities to study the Standard Model of
particle physics, narrowing down the parameter space for the elusive
Higgs Boson and possibly making ground breaking discoveries like Supersymmetry.
Top Quark Physics
Measuring the properties of the top quark is of primary importance for
several reasons. The magnitude of the mass of the top quark, which is
35 times more massive than its next heavier colleague, the bottom
quark, suggests a special role the top quark might play in the
mechanism of electroweak symmetry breaking. Some authors also derive
from the prominent role it plays in the fermion mass spectrum that its
mass be the fundamental parameter of a more basic, underlying new
theory.
The mass of the top quark as a Standard Model parameter is furthermore
distinguished by the fact that many radiative corrections to electroweak
observables exhibit a quadratical dependence on it. Reducing the error on the
top mass, currently known to about 3%, is therefore directly carrying over in
the uncertainties of Standard Model predictions of other observables; most
notably -- in conjunction with the already rather precisely known W-boson mass
-- a prediction for the Higgs mass can be obtained. These predictions suggest
that the Higgs boson be light, and global electroweak fits extract it to MH
= 81+5233GeV. Clearly, decreasing the uncertainty on the input
parameters will improve this result, and Run II is aiming to reduce the top
quark mass uncertainty to about 1%. This will require huge efforts in
understanding the detector response.
Furthermore, Run II will observe for the first time so-called single top
production, an electroweak process which will allow for the first time the
extraction of top quark properties like its spin and quark mixing matrix
element Vtb. The single top production cross section can also be sensitive to
non-standard couplings of the top quark, making it a very interesting
observable to search for new physics. Due to the electroweak nature of single
top production, top quarks will be preferentially produced in the very forward
region of the detector, which was heavily upgraded in Run II, most
notably with the PLUG Calorimeter, a UCLA 'baby'.
Hardware Projects
We high energy physicists have the privilege to play around with a lot
gadgets. I am particularly interested in tracking detectors. I have
worked on the
Backward Drift Chamber of the
H1 Experiment at DESY and on the
Semiconductor Tracker (SCT) of the ATLAS Experiment to be built at CERN . I was project leader of Silicon
Tracking of the CDF experiment at Fermilab and currently develop
a beam condition monitoring system based on radiation hard Diamond detectors for CDF.
My
complete
list of publications is in the SLAC SPIRES database.
Back to home page for Rainer Wallny
Rainer Wallny
Last modified: Sat Sep 25 19:57:06 CDT 2004