OHEP Physics highlights from the past year

1
OHEP Physics highlights from the past year
The standard model has one missing ingredient
(the Higgs). It is widely believed that the SM
will fail and new phenomena will emerge at the
TeV scale.
Based on 1 fb-1 (15 of expected data), new
Tevatron top mass (170.9 1.8 GeV) (example) and
new W mass (80.413 0.048 GeV) push the favored
SM Higgs mass lower.
The 68 allowed value is actually outside the
experimentally allowed region shown in green.
Low mass Higgs is accessible at Tevatron and
difficult at LHC.
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Direct Tevatron searches are gaining on the SM
Higgs. Individual experiments rule out signal at
5 -10 times expected cross section with 1 fb-1.
With full data sample (8fb-1), average of
experiments (not done yet) and improvements in
analysis, can rule out SM Higgs if mass lt 180 GeV
or discover for mass lt 120 GeV.
3
BS (bound state of b and anti-s quarks) mix to
anti-BS through intermediate exchanges of W
bosons and top quarks. The first definitive
observation of the oscillation was observed by
the CDF experiment. The rate is sensitive to new
particles/physics such as supersymmetry. The
measured oscillation frequency (17.8 ps-1) is
consistent with SM prediction. Ratio of Bs and
Bd mixing cancels poorly known QCD corrections.
Fourier analysis of mixing amplitude shows peak
at 17.8 ps-1
Folding many oscillation periods shows clear
oscillation.
4
Decays of B and K mesons probe the three
generation quark mixing matrix and the source of
CP violation. For the first time BaBar has
observed CP violation in Bd ? pp and Kp which
constrains the angle alpha.
BaBar has also shown evidence that D0 mesons
(charm and anti-up quark bound state) oscillate
to anti-D0 mesons. This process is sensitive to
CP violation effects in the down-type quarks.
The tour de force measurement yields a result
that is consistent with the Standard Model
expectation.
5
The couplings among the Electroweak gauge bosons
(g, W, Z) are fixed by the Standard Model. In
Wg production, the SM gauge coupling term
interferes with other processes predicting a dip
in the g angular distribution. This dip has been
observed for the first time, and limits on
anomalous non-SM couplings are improved.
6
The strong interaction (QCD) process is
responsible for the top-anti-top quark pair
production observed at the Tevatron. For the
first time, production of single top quarks via
the weak interaction has been observed by the DØ
experiment. The complex analysis used new
techniques taken from artificial intelligence
methods. The cross section is about 1/3 that for
strong t-tbar production. This observation
provides the first direct measurement of the
quark mixing matrix element connecting the top
and bottom quarks. The techniques developed are
applicable for future searches for the Higgs
boson.
7
Earlier results from LANL suggested the existence
of a 4th neutrino species that does not interact
with the electroweak interaction. In a new
result, the MiniBoone collaboration has ruled out
this possibility, and confirms the Standard Model
picture of three neutrino generations. The
MiniBoone result (black line) rules out the
region to the right of the curve.
8
The direct search for dark matter in terrestrial
experiments have been led by the CDMS experiment
in a Minnesota mine. The 2005 results were the
best limits on dark matter particles to date.
The XENON experiment has improved these by an
order of magnitude in 2006. The results expected
in 2007 push into the region where supersymmetric
particle dark matter WIMP candidates should exist.
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The LHC is expected to produce first collisions
late in 2007, and start full energy (14 TeV)
operation in 2008. The major experiments ATLAS
and CMS have been built and installed with large
contributions from US physicists. The LHC physics
program is a broad attack on the TeV scale the
experiments should observe the Higgs boson at any
feasible mass, and discover the new physics
widely expected to supplant the Standard Model.
2000 tonne CMS magnet being lowered to the cavern
ATLAS toroid coils installed
10
At SLAC, a 42 GeV electron beam driven into an 85
cm long plasma creates wakefields that accelerate
the tail of the bunch by a factor of 2 (46
GeV/m). RD continues to try to turn this result
into a practical afterburner to boost the
energy of beams in table top dimensions.
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At LBNL, a 40 TW laser creates a plasma wake
field in a 3.3 cm capillary which accelerates a
trailing electron beam by 1 GeV (30 GeV/m). The
next phases will attempt multi-cell acceleration
to 10 GeV.
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VERITAS 50 GeV to 50 TeV gamma rays and dark
matter candidates, observed with a ground-based
4-telescope Cerenkov array. Now in engineering
run in Whipple base camp (NM). Will move to Kitt
Peak for 2 year run. (with NSF, Smithsonian,
foreign agencies)
13
GLAST Observe 20 MeV to 300 GeV gamma rays in
space. The primary Large Area Telescope
instrument was developed under SLAC management
and is now installed and under test. Launch is
scheduled for Dec. 2007 (with NASA,
foreign agencies).
Large Area Telescope
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Pierre Auger cosmic ray observatory to study
very high energy cosmic rays is operating at a
3000 km2 site in Argentina (with NSF and foreign
agencies). Operating with all florescence
detectors and 1250 out of 1600 Cerenkov
telescopes as of end 2006. Final installation to
complete in mid-2007. First results on cosmic
ray fluxes have been reported.
Water Cherenkov surface detectors
Fluorescence telescopes
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Dark Energy Experiments We are investigating
future space and/or ground telescopes in
cooperation with NASA and NSF.

• Dark Energy Task Force (HEPAP/AAAC subpanel)
  recommended a mix of experiments with
  complementary measurements to address dark
  energy.
• HEPAP P5 subpanel recommended small-scale
  ground-based DES project that will provide
  significant advances in our knowledge of Dark
  Energy in the near term. P5 also recommended
  that RD be done for large-scale ground-based and
  space-based dark energy experiments to get them
  to a preliminary design stage.
• NRC Beyond Einstein Program Assessment Committee
  study will report in Sept. 2007 which of the 5
  Beyond Einstein missions should go first.
• DOE OHEP Status
• Supernova Cosmology Project Nearby Supernova
  Factory continue data-taking
• Doing RD for SuperNova Acceleration Probe
  (SNAP) concept for JDEM
• Have 32 Dark Energy RD proposals decisions at
  the end of May