5,169 research outputs found
B and D Spectroscopy at LEP
Results from the four LEP experiments ALEPH, DELPHI, L3, and OPAL on the
spectroscopy of B and charmed mesons are presented. The predictions of Heavy
Quark Effective Theory (HQET) for the masses and the widths of excited L=1 B
mesons are supported by a new measurement from L3. A few B_c candidate eve nts
have masses consistent with the recent CDF observation and the predictions. New
results on Ddstar production and B -> Ddstar l nu are also presented. The
evidence for a Dstarpr meson reported recently by DELPHI is not supported by
OPAL and CLEO.Comment: 10 pages, 6 figure
Multianode Photo Multiplier Tubes as Photo Detectors for Ring Imaging Cherenkov Detectors
The 64-channel Multianode Photo Multiplier (MaPMT) has been evaluated as a
candidate for the LHCb Ring Imaging Cherenkov (RICH) photo detectors. We
present result from data taken with a 3x3 array of closely packed MaPMTs
mounted onto the RICH 1 prototype vessel, exposed to charged particle beams at
CERN, and read out at LHC speed. Using a LED light source, we have performed
spatial light scans to study the light collection efficiency of the MaPMTs We
have also measured the performance of the MaPMTs as a function of the applied
high voltage. Different dynode resistor chains have been used to study the
tubes at low gains. In addition, we have studied the behaviour of the MaPMT in
magnetic fields.Comment: 5 pages, 6 figures, 8 .eps files, RICH2002 conference, Pylo
LHCb Upgrade Plans
The LHCb experiment will operate for about five years at a luminosity of
2x10^32 cm^-2 s^-1 and plans are to accumulate a data sample of ~10 fb^-1. Here
we present the physics programme and detector design for a future high
luminosity phase of the LHCb experiment. An upgraded LHCb experiment would
operate at ten times the design luminosity, i.e. at ~2x10^33 cm^-2 s^-1 and
aims to collect a data sample of ~100 fb^-1 over five years. This programme
would allow the probe of new physics at an unprecedented level. Key
measurements include the B^0_s mixing phase phi_s in B^0_s -> J/\psi phi and
B^0_s -> phi phi decays with a significant sensitivity to the small Standard
Model prediction and a very precise measurement of the CKM angle gamma in tree
diagram decays. Initial studies of the modified LHCb trigger and detectors are
presented. The upgraded LHCb experiment can run with or without an LHC
luminosity upgrade.Comment: 6 pages, 2 figures, to appear in the proceedings of International
Conference on B-Physics at Hadron Machines (Beauty 2006), Oxford, England,
25-29 Sep 200
Monte Carlo Studies of a Novel LiF Radiator for RICH Detectors
We show that a multifaceted LiF radiator produces more Cherenkov light and
has better resolution per photon than a flat radiator slab when used in a ring
imaging Cherenkov counter. Such a system is being considered for the CLEO III
upgrade.Comment: 9 page
LHCb's Potential to Measure Flavour-Specific CP-Asymmetry in Semileptonic and Hadronic Decays
"The CP asymmetry in Bs-Bsbar mixing, denoted as a^s_{fs}, is sensitive to new weak phases in the presence of physics beyond the Standard Model. This can be probed through a measurement of the time-dependent charge asymmetry A^s_{fs}(t) in flavour-specific decays. This note describes the LHCb strategy to measure a^s_{fs} using a time-dependent method, in flavour untagged decays of Bs->Ds mu nu and Bs->Ds pi. We also investigate a measurement of the difference of a^s_{fs} and a^d_{fs} in Bs->Ds mu nu and Bd->Dmu nu decays which allows to control the systematic uncertainty that arise from detection asymmetries.
A New Model for Fermion Masses in Supersymmetric Grand Unified Theories
We present a simple model for fermion mass matrices and quark mixing in the
context of supersymmetric grand unified theories and show its agreement with
experiment. Our model realizes the GUT mass relations , , in a new way and is easily consistent with values of
suggested by MSSM fits to LEP data.Comment: Latex, 8 p., ITP-SB-93-37 (revised version contains minor changes in
some wording and citations; no changes in analytic or numerical results.
Anomalous coupling effects in exclusive radiative B-meson decays
The top-quark FCNC processes will be searched for at the CERN LHC, which are
correlated with the B-meson decays. In this paper, we study the effects of
top-quark anomalous interactions in the exclusive radiative and decays. With the current experimental data of
the branching ratios, the direct CP and the isospin asymmetries, bounds on the
coupling from and
from decays are derived,
respectively. The bound on from is generally compatible with that from . However, the isospin asymmetry further
restrict the phase of , and the combined bound results
in the upper limit, , which is lower than the
CDF result. For real , the upper bound on is about of the same order as the discovery
potential of ATLAS with an integrated luminosity of . For
decays, the NP contribution is enhanced by a large CKM factor
, and the constraint on coupling is rather
restrictive, . With refined
measurements to be available at the LHCb and the future super-B factories, we
can get close correlations between and the rare
decays, which will be studied directly at the LHC ATLAS and CMS.Comment: 25 pages, 15 figures, pdflate
Search for Extra Dimensions in Boson and Fermion Pair Production in e+e- Interactions at LEP
Extra spatial dimensions are proposed by recent theories that postulate the
scale of gravity to be of the same order as the electroweak scale. A sizeable
interaction between gravitons and Standard Model particles is then predicted.
Effects of these new interactions in boson and fermion pair production are
searched for in the data sample collected at centre-of-mass energies above the
Z pole by the L3 detector at LEP. In addition, the direct production of a
graviton associated with a Z boson is investigated. No statistically
significant hints for the existence of these effects are found and lower limits
in excess of 1 TeV are derived on the scale of this new theory of gravity
Measurement of Hadron and Lepton-Pair Production at 130GeV < \sqrt{s} < 189 GeV at LEP
We report on measurements of e+e- annihilation into hadrons and lepton pairs.
The data have been collected with the L3 detector at LEP at centre-of-mass
energies between 130 and 189 GeV. Using a total integrated luminosity of 243.7
pb^-1, 25864 hadronic and 8573 lepton-pair events are selected for the
measurement of cross sections and leptonic forward-backward asymmetries. The
results are in good agreement with Standard Model predictions
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