proposal2007_draft09.. - Henry A. Rowland Department of Physics ...

2 Project Description
Elementary particle physics is currently at an exciting juncture. The Standard Model has proven
to be a remarkably successful description of essentially all experimentally determined phenomena.
Nevertheless, there are significant “holes” in our knowledge of the micro-physical universe: we do
not know the origin of “dark matter” or “dark energy”, we do not know the source of spontaneous
symmetry breaking, we do not fully know the quark mixing matrix or whether it is solely responsible
for the CP violation observed in the neutral K and B sectors, and we know almost nothing about
the analogous phenomena occurring in the neutral lepton sector. We do know that there is good
reason to believe that spontaneous symmetry breaking (SSB) as described by the Minimal Standard
Model is unlikely to be correct/complete. The theory has unstable high energy behavior and
such pathologies are an indication that new phenomena are lurking at larger mass scales. These
phenomena may contribute to the mass and energy balance of the universe. Precise electroweak
measurements suggest that the mass scale that plays the role of the Higgs in the theory is “light”
( 200 GeV). This fact suggests that the LHC should be sensitive to whatever phenomena occur
at the electroweak scale.
A second observation about the Standard Model is that although the CKM matrix can probably
accommodate the CP violation observed in the neutral K and B systems, it can not be responsible
for the matter dominance of the universe. If one assumes that the initial state of the universe
did not contain an excess of matter over antimatter, then there is probably another source of CP
violation waiting to be discovered. Experiments that probe the nature of CP violation still have
some chance of finding something new. The Tevatron is already doing useful CP and CP-related
measurements. Given current luminosity projections, the B-Physics program is likely to continue
to yield interesting results.
These realities have shaped the direction of our group. We are proposing a program of hadron
collider physics within the CDF Collaboration at the Tevatron and the CMS Collaboration at the
LHC. We plan to finish several B-Physics measurements at CDF with residual manpower and focus
on search for SSB at the LHC with most of our resources. In the very long term, we see the linear
collider and cosmology as exciting future directions of the group.
One can ask how a small group can have an impact on these programs? The search for new phenomena
at the LHC will rely on several capabilities: lepton reconstruction, photon reconstruction,
b-quark/τ-lepton reconstruction, and the measurement of missing transverse energy. The identification
of b-quarks/τ-leptons relies on a rather small and sophisticated technology. This technology
is actually a good match to a small group and mates nicely with the Tevatron B-Physics program.
The JHU group has contributed to the silicon vertex tracking of the CDF experiment for 18 years.
The group decided to leverage that expertise when it joined the CMS pixel effort. The CMS pixel
system is the smallest subsystem in the experiment which, despite having grown to approximately
100 collaborators, is still quite undermanned. The JHU group currently dominates the pixel offline
software effort and the pixel alignment effort. We have already demonstrated that a few people
can have significant impact on an LHC experiment if their efforts are carefully targeted.
A newer area of technical expertise is in the management of very large distributed databases.
A system called Frontier was developed by a Fermilab-JHU collaboration to address problems with
remote CDF computing. Frontier is now an essential element of the CMS computing grid. The
JHU group is at the forefront of its implementation and management.
The science program at the LHC is enormously exciting because we know only that the Minimal
Standard Model with a single physical Higgs state is very unlikely to be correct and that the existing
theoretical alternatives are all problematic. This suggests that the correct picture has not yet been
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