246 research outputs found
Search for New Particles at LEP
The latest preliminary results of the searches for Higgs bosons and
Supersymmetric particles at LEP are reviewed. The results include the
data-taking in 1999 up to center-of-mass energies of 196 GeV. The combination
of the results from the four LEP experiments leads to a significant increase of
the detection sensitivity. No indication of a signal has been observed. In the
Standard Model (SM) a lower limit of 102.6 GeV on the mass of the Higgs boson
is set at 95% CL. In extended models, stringent limits are also set on the HZZ
coupling. Interpretations in the Minimal extension of the Supersymmetric
Standard Model (MSSM) are given and the importance of general MSSM parameter
scans is emphasized. In general scans, the limit on the mass of the lightest
scalar Higgs boson is about 7 GeV lower in comparison with benchmark results.
The data also constrains charged Higgs bosons of a general two-doublet model
and Supersymmetric partners of the SM particles.Comment: 16 pages, 38 figure
Status of Higgs Boson Searches at the Tevatron
Over the last years the Tevatron Run-II has extended several limits on Higgs
boson masses and coupling which were pioneered during the LEP accelerator
operation between 1989 and 2000. Higgs boson searches will also be at the
forefront of research at the LHC. This review concisely discusses the
experimental constraints set by the CDF and D0 collaborations in winter
2008/2009 at the beginning of the LHC era. Model-independent and
model-dependent limits on Higgs boson masses and couplings have been set and
interpretations are discussed both in the Standard Model and in extended
models. Recently, for the first time the Tevatron excludes a SM Higgs boson
mass range (160-170 GeV) beyond the LEP limit at 95% CL. The experimental
sensitivities are estimated for the completion of the Tevatron programme.Comment: Presented at WONP'09, 18 pages, 38 figure
Alignment of the Central D-Zero Detector
The alignment procedure of the Silicon Microstrip Tracker, SMT, and the
Central Fiber Tracker, CFT, is described. Alignment uncertainties and resulting
systematic errors in physics analyses are addressed.Comment: 20 pages, 33 figures, presented at workshop on Tracking In high
Multiplicity Environments (TIME'05) Zurich, October 3-7, 2005. Proceedings
Nucl. Inst. Methods
Charge Transfer Inefficiency Studies for CCD Vertex Detectors at a LC
The Linear Collider Flavour Identification (LCFI) collaboration studies CCD
detectors for quark flavour identification in the framework of a future linear
e+e- collider. The flavour identification is based on precision reconstruction
of charged tracks very close to the interaction point. Therefore, this detector
will be exposed to a high level of radiation and thus an important aspect of
the vertex detector development are radiation hardness studies. Results of
detailed simulations of the charged transport properties of a CCD prototype
chip are reported and compared with initial measurements. The simulation
program allows to study the effect of radiation damage after the exposure of
the detector to a realistic radiation dose, which is expected in the
environment of detector operation at a future LC.Comment: 6 pages, 10 figures, Proceedings 2005 International Linear Collider
Workshop - Stanford, U.S.
Searches for Higgs Bosons at LEP2
The latest results of Higgs boson searches from the four LEP experiments,
ALEPH, DELPHI, L3 and OPAL, are reviewed using the data taken in 1996 at
center-of-mass energies between 161 and 172 GeV. No signal was observed. The
95% CL combined lower mass limit for the Minimal Standard Model (MSM) Higgs
boson has increased from 66 GeV at LEP1 to 77.5 GeV with the first LEP2 data.
In the framework of the Two Higgs Doublet Model, the charged Higgs boson mass
limit has increased from 44 GeV to 54.5 GeV, independent of the decay branching
ratio. Large new (m_h,tan_beta) and (m_h,m_A) parameter regions are excluded in
the framework of the Minimal Supersymmetric extension of the Standard Model
(MSSM). Preliminary results from the 1997 data-taking at 183 GeV are presented,
and the prospects for a discovery in the near future are given.Comment: 20 pages, LaTeX, 22 figures, presented at the 1st Int. Workshop on
Non-Accelerator Physics, Dubna, July 1997, to be published in the
proceedings, and at the Aspen Center for Physics, August 199
MSSM Higgs Boson Searches at LEP
Final results from the MSSM Higgs boson searches from the LEP experiments
ALEPH, DELPHI, L3 and OPAL are presented. The results are statistically
combined and the statistical significance for signal and background hypotheses
are given. Upper bounds on the production cross sections are set for several
Higgs-like topologies. Interpretations for six benchmark scenarios in the MSSM,
both for CP-conserving and CP-violating scenarios, are given. Limits on the
tan(beta) parameter, and in some scenarios upper limits on the neutral Higgs
boson masses are set.Comment: 7 pages, 18 figures. Presented at the 13th International Conference
on Supersymmetry and Unification of Fundamental Interactions (SUSY'05),
Durham, UK, July 18-23, 200
New Physics Searches at the Tevatron and the LHC
The Tevatron Run-II started data-taking in spring 2001 and several searches
for new particles have been performed. The preliminary 2005 results are
concisely reviewed for the experiments CDF and D0. Model-independent and
model-dependent limits on Higgs boson and Supersymmetric particle production
are set and interpretations are given. Several limits from the LEP era have
been extended. The outlook for the Tevatron and the prospects for the ATLAS and
CMS experiments at the LHC for selected searches are briefly addressed.Comment: 32 pages, 44 figures, presented at PHENO'05 and Aspen Collider
Physics Workshop 200
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