2,894 research outputs found
A Development Environment for Visual Physics Analysis
The Visual Physics Analysis (VISPA) project integrates different aspects of
physics analyses into a graphical development environment. It addresses the
typical development cycle of (re-)designing, executing and verifying an
analysis. The project provides an extendable plug-in mechanism and includes
plug-ins for designing the analysis flow, for running the analysis on batch
systems, and for browsing the data content. The corresponding plug-ins are
based on an object-oriented toolkit for modular data analysis. We introduce the
main concepts of the project, describe the technical realization and
demonstrate the functionality in example applications
High-Pressure Amorphous Nitrogen
The phase diagram and stability limits of diatomic solid nitrogen have been
explored in a wide pressure--temperature range by several optical spectroscopic
techniques. A newly characterized narrow-gap semiconducting phase has
been found to exist in a range of 80--270 GPa and 10--510 K. The vibrational
and optical properties of the phase produced under these conditions
indicate that it is largely amorphous and back transforms to a new molecular
phase. The band gap of the phase is found to decrease with pressure
indicating possible metallization by band overlap above 280 GPa.Comment: 5 pages, 4 figure
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Search for lepton-flavour-violating decays of Higgs-like bosons.
A search is presented for a Higgs-like boson with mass in the range 45 to 195 GeV/c2 decaying into a muon and a tau lepton. The dataset consists of proton-proton interactions at a centre-of-mass energy of 8 TeV , collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb-1 . The tau leptons are reconstructed in both leptonic and hadronic decay channels. An upper limit on the production cross-section multiplied by the branching fraction at 95% confidence level is set and ranges from 22 pb for a boson mass of 45 GeV/c2 to 4 pb for a mass of 195 GeV/c2
Observation of an Excited Bc+ State
Using pp collision data corresponding to an integrated luminosity of 8.5 fb-1 recorded by the LHCb experiment at center-of-mass energies of s=7, 8, and 13 TeV, the observation of an excited Bc+ state in the Bc+π+π- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(Bc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Bc+ mass. It is consistent with expectations of the Bc∗(2S31)+ state reconstructed without the low-energy photon from the Bc∗(1S31)+→Bc+γ decay following Bc∗(2S31)+→Bc∗(1S31)+π+π-. A second state is seen with a global (local) statistical significance of 2.2σ (3.2σ) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(Bc+) MeV/c2, and is consistent with the Bc(2S10)+ state. These mass measurements are the most precise to date
Peripherical processes 2 3 and 2 4 in QED and QCD in high energy collisions
Differential cross section of processes with high energy
collisions in frames of QED: creation of scalar, pseudoscalar and lepton pair -
are considered in Weizs\"acker - Williams approximation. In frames of QCD
processes with conversion of initial proton (antiproton) to fermionic jets
accompanied with one gluon jet as well as the state of two gluons and
quark-antiquark pair (with out rapidity gap) are considered in frames of
effective Reggion action of theory of Lipatov. Process of creation of a Higgs
boson accompanied with two fermionic jets is considered. The azimuthal
correlation in process of two gluon jet separated by rapidity gap is
investigated. Effects of gluon reggeization are taken into account. Some
distributions are illustrated by numerical calculations.Comment: 17 pages, 6 figure
Measurement of the inelastic pp cross-section at a centre-of-mass energy of 13TeV
The cross-section for inelastic proton-proton collisions at a centre-of-mass energy of 13TeV is measured with the LHCb detector. The fiducial cross-section for inelastic interactions producing at least one prompt long-lived charged particle with momentum p > 2 GeV/c in the pseudorapidity range 2 < η < 5 is determined to be ϭ acc = 62:2 ± 0:2 ± 2:5mb. The first uncertainty is the intrinsic systematic uncertainty of the measurement, the second is due to the uncertainty on the integrated luminosity. The statistical uncertainty is negligible. Extrapolation to full phase space yields the total inelastic proton-proton cross-section ϭ inel = 75:4 ± 3:0 ± 4:5mb, where the first uncertainty is experimental and the second due to the extrapolation. An updated value of the inelastic cross-section at a centre-of-mass energy of 7TeV is also reported
Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets
This document is the Technical Design Report covering the two large
spectrometer magnets of the PANDA detector set-up. It shows the conceptual
design of the magnets and their anticipated performance. It precedes the tender
and procurement of the magnets and, hence, is subject to possible modifications
arising during this process.Comment: 10 pages, 14MB, accepted by FAIR STI in May 2009, editors: Inti
Lehmann (chair), Andrea Bersani, Yuri Lobanov, Jost Luehning, Jerzy Smyrski,
Technical Coordiantor: Lars Schmitt, Bernd Lewandowski (deputy),
Spokespersons: Ulrich Wiedner, Paola Gianotti (deputy
Characterization of primary neurospheres generated from mouse ventral rostral hindbrain
Serotonergic (5-HT) neurons of the reticular formation play a key role in the modulation of behavior, and their dysfunction is associated with severe neurological and psychiatric disorders, such as depression and schizophrenia. However, the molecular mechanisms underlying the differentiation of the progenitor cells and the specification of the 5-HT phenotype are not fully understood. A primary neurosphere cell-culture system from mouse ventral rostral hindbrain at embryonic day 12 was therefore established. The generated primary neurospheres comprised progenitor cells and fully differentiated neurons. Bromodeoxyuridine incorporation experiments in combination with immunocytochemistry for neural markers revealed the proliferation capacity of the neural multipotent hindbrain progenitors within neurospheres and their ability to differentiate toward the neuronal lineage and serotonergic phenotype. Gene expression analysis by reverse transcription with the polymerase chain reaction showed that the neurospheres were regionally specified, as reflected by the expression of the transcription factors Gata2 and Pet1. Treatment of dissociated primary neurospheres with exogenous Shh significantly increased the number of 5-HT-immunopositive cells compared with controls, whereas neutralization of endogenous Shh significantly decreased the number of 5-HT neurons. Thus, the primary neurosphere culture system presented here allows the expansion of hindbrain progenitor cells and the experimental control of their differentiation toward the serotonergic phenotype. This culture system is therefore a useful model for in vitro studies dealing with the development of 5-HT neurons
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Measurement of CP observables in the process B <sup>0</sup> → DK <sup>*0</sup> with two- and four-body D decays
Measurements of observables in decays are presented,
where represents a superposition of and states. The
meson is reconstructed in the two-body final states , ,
and , and, for the first time, in the four-body final
states , and .
The analysis uses a sample of neutral mesons produced in proton-proton
collisions, corresponding to an integrated luminosity of 1.0, 2.0 and 1.8 collected with the LHCb detector at centre-of-mass energies of
7, 8 and 13 TeV, respectively. First observations of the decays
and are
obtained. The measured observables are interpreted in terms of the
-violating weak phase
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