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Particle physics is standing
within reach of new discoveries. The undiscovered symmetries
of nature which unify the fundamental forces and particles,
the puzzle of dark matter and energy, and the apparent lack
of antimatter in our Universe, all these mysteries are about
to be uncovered at an unprecedented energy scale with the
Large Hadron Collider. The discovery of new particles at the
LHC will depend on the ability to distinguish their decay
products from random particles produced in the high-energy
collisions. An essential element of this is the alignment of
thousands of silicon detectors that track the particles'
paths which must be understood to micron precision.
It will also be crucial to make a discovery and to determine the quantum numbers
(such as spin and parity) of the new particles, to determine their masses
and their couplings to Standard Model fields as accurately
as possible. The research project is focused on these two important
aspects. You may refer to these two recent articles we wrote on
spin determination of single-produced resonances at hadron colliders
and
alignment of the CMS silicon tracker during commissioning with cosmic rays.
The latter is the first journal article published by the full CMS collaboration.
Prior to LHC direct access to new fundamental particles was beyond the energy reach of
operating accelerators (with potential exception of the Tevatron, but no new physics has
has been discovered there yet). I had developed new ways to search
for them via rare virtual loop decays. On the BABAR
experiment, I targeted spin-correlation measurements in its
decays to mesons with non-zero spin where new particles in
virtual loops might cause different spin alignments. See an example of our
spin angular analysis.
Prior to that on the CLEO experiment I discovered the first gluonic
penguin loop decays via the observation of flavor changing
neutral current process B->η'K. On BABAR, I
discovered the B meson loop decays to two spin-one particles,
such as B->φ K*, and developed techniques for their
angular analysis. The result was a surprisingly large
transverse polarization fraction, which contradicted all
expectations and may become evidence for new particles and
interactions. An alternative indirect way to search for new effects is
to constrain the Unitarity Triangle, which describes the only
known source of CP violation but is believed to be
insufficient to produce our matter-dominated Universe. One of
the unconstrained angles of the Unitarity Triangle α was
expected to be measured with B->ππ decays. However, I
led a discovery of a new, more complicated decay B->ρρ
and demonstrated that it gives the smallest uncertainty for
the measurement of α. This discovery provided a
determination of α with a precision that many believed
could not be achieved.
The above scientific questions shaped the directions of my
group. To read more about the present CMS or prior BABAR activities, click on
the CMS or
BABAR links.
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