6,447 research outputs found
Semileptonic B Decays in Babar
BaBar measurements involving semileptonic decays of B mesons are reviewed.
Attention is focused on the extraction of |Vub| and |Vcb| elements of the
Cabibbo-Kobayashi-Maskawa quark mixing matrix. Recent results of inclusive and
exclusive approaches are presented.Comment: 6 pages, 4 figures, Contributed to 11th Lomonosov Conference on
Elementary Particle Physic
LHCb Level-0 Trigger Detectors
The calorimeter and muon systems are essential components to provide a
trigger for the LHCb experiment. The calorimeter system comprises a
scintillating pad detector and pre-shower, followed by electromagnetic and
hadronic calorimeters. The calorimeter system allows photons, electrons and
hadrons to be identified, and their energy to be measured. The muon system
consists of five measuring stations equipped with Multi-Wire Proportional
Chambers (MWPCs) and triple-Gas Electron Multiplier (GEM) detectors, separated
by iron filters. It allows the muons identification and transverse momentum
measurement. The status of the two systems and their expected performance is
presented.Comment: 4 pages, 2 figures, proceedings of "X Pisa Meeting on Advanced
Detectors", May 21-27, 2006 La Biodola, Isola d'Elba (Italy
A cortical based model of perceptual completion in the roto-translation space
We present a mathematical model of perceptual completion and formation
of subjective surfaces, which is at the same time inspired by the architecture
of the visual cortex, and is the lifting in the 3-dimensional rototranslation group of
the phenomenological variational models based on elastica functional. The initial
image is lifted by the simple cells to a surface in the rototraslation group and the
completion process is modelled via a diffusion driven motion by curvature. The
convergence of the motion to a minimal surface is proved. Results are presented
both for modal and amodal completion in classic Kanizsa images
A tool for the LHCb MWPC production monitoring: the LNF on-line database
The LHCb Muon detector system is made of several (1368) Multi Wire Proportional Chambers (MWPCs). Those chambers differ in size, readout and constructing materials and are built in various countries: their assembly takes place in different sites and foresee many steps. To ensure the production quality and keep track of panels/chambers production an on-line database has been set up. This web based tool allows an easy sharing of the information: the database update is made possible trough a web interface. The update is easy and reliable. The interface helps the information sharing in different sites and helps optimizing the production rate by allowing feedback on production needs and quality between sites contributing to the production chain. The planning is made using the information on the material availability. Quality tests and crosschecks are made easier, as well as the overall production monitoring. The tool has been developed using mySQL, PHP, ROOT and PERL software languages
B Physics at LHC
Three experiments, among the LHC project, are getting ready to explore the b
quark flavour sector. While ATLAS and CMS are general purpose experiments,
where the study of B mesons is going to proceed in parallel with the Higgs
boson and supersymmetry searches, the LHCb experiment is devoted to B physics
studies. The key parameters entering the physics analyses and the performances
achieved in all the three experiments are presented. Given the large B physics
program foreseen in the LHC experiments, the studies reported in this paper
have been selected as those with higher likelihood to provide solid and
interesting new results on Standard Model validation and New Physics processes
search with early data.Comment: Invited talk at the Hadron Collider Physics Symposium (HCP2008),
Galena, Illinois, USA, May 27-31, 2008; 11 pages, LaTeX, 8 eps figure
Tevatron and LHCb
I review some recent flavour physics results of CDF and D0 experiments at the Tevatron and discuss the expected performance of the LHCb experiment at LHC. While the Tevatron experiments have proven the potential for flavour
physics studies at hadron machines, producing outstanding results in the Bs sector, the LHCb experiment, that has just started to take data at the LHC, is expected to
significantly improve the precision reached in some key measurements already with the data collected in the first LHC run (expected to end in 2011)
Rare B decays at LHC
The LHC collider will soon produce the largest sample of B mesons, opening several new paths to the discovery of New Physics processes through the study of their rare and very rare decays. The strategies for the data analysis and the
expected performances for several key decay channels are reviewed and compared for the three LHC experiments that are ready to reconstruct and select the B mesons: LHCb, ATLAS and CMS
Microbial processes and bacterial populations associated to anaerobic treatment of sulfate-rich wastewater
A pilot-scale (1.2 m3) anaerobic sequencing batch biofilm reactor (ASBBR) containing mineral coal for biomass attachment was fed with sulfate-rich wastewater at increasing sulfate concentrations. Ethanol was used as the main organic source. Tested COD/sulfate ratios were of 1.8 and 1.5 for sulfate loading rates of 0.65–1.90 kgSO42−/cycle (48 h-cycle) or of 1.0 in the trial with 3.0 gSO42− l−1. Sulfate removal efficiencies observed in all trials were as high as 99%. Molecular inventories indicated a shift on the microbial composition and a decrease on species diversity with the increase of sulfate concentration. Beta-proteobacteria species affiliated with Aminomonas spp. and Thermanaerovibrio spp. predominated at 1.0 gSO42− l−1. At higher sulfate concentrations the predominant bacterial group was Delta-proteobacteria mainly Desulfovibrio spp. and Desulfomicrobium spp. at 2.0 gSO42− l−1, whereas Desulfurella spp. and Coprothermobacter spp. predominated at 3.0 gSO42− l−1. These organisms have been commonly associated with sulfate reduction producing acetate, sulfide and sulfur. Methanogenic archaea (Methanosaeta spp.) was found at 1.0 and 2.0 gSO42− l−1. Additionally, a simplified mathematical model was used to infer on metabolic pathways of the biomass involved in sulfate reduction
Measurement of the electron reconstruction efficiency at LHCb
The single electron track-reconstruction efficiency is calibrated using a sample corresponding to 1.3 fb−1 of pp collision data recorded with the LHCb detector in 2017. This measurement exploits B
+ → J/ψ(e
+
e
−
)K
+ decays, where one of the electrons is fully reconstructed
and paired with the kaon, while the other electron is reconstructed using only the information of
the vertex detector. Despite this partial reconstruction, kinematic and geometric constraints allow
the B meson mass to be reconstructed and the signal to be well separated from backgrounds. This
in turn allows the electron reconstruction efficiency to be measured by matching the partial track
segment found in the vertex detector to tracks found by LHCb’s regular reconstruction algorithms.
The agreement between data and simulation is evaluated, and corrections are derived for simulated electrons in bins of kinematics. These correction factors allow LHCb to measure branching
fractions involving single electrons with a systematic uncertainty below 1%
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