Search results for "Particle physics"
showing 10 items of 6826 documents
Measurement of neutrino-induced charged-current charged pion production cross sections on mineral oil atEν∼1 GeV
2011
Using a high-statistics, high-purity sample of {nu}{sub {mu}-}induced charged current, charged pion events in mineral oil (CH{sub 2}), MiniBooNE reports a collection of interaction cross sections for this process. This includes measurements of the CC{pi}{sup +} cross section as a function of neutrino energy, as well as flux-averaged single- and double-differential cross sections of the energy and direction of both the final-state muon and pion. In addition, each of the single-differential cross sections are extracted as a function of neutrino energy to decouple the shape of the MiniBooNE energy spectrum from the results. In many cases, these cross sections are the first time such quantities…
Seesaw Majoron Model of Neutrino Mass and Novel Signals in Higgs Boson Production at LEP
1998
We perform a careful study of the neutral scalar sector of a model which includes a singlet, a doublet, and a triplet scalar field under $SU(2)$. This model is motivated by neutrino physics, since it is simply the most general version of the seesaw model of neutrino mass generation through spontaneous violation of lepton number. The neutral Higgs sector contains three CP-even and one massive CP-odd Higgs boson $A$, in addition to the massless CP-odd majoron $J$. The weakly interacting majoron remains massless if the breaking of lepton number symmetry is purely spontaneous. We show that the massive CP-odd Higgs boson may invisibly decay to three majorons, as well as to a CP-even Higgs $H$ bo…
Site-by-site tracking of signal transduction in an azidophenylalanine-labeled bacteriophytochrome with step-scan FTIR spectroscopy
2021
Signal propagation in photosensory proteins is a complex and multidimensional event. Unraveling such mechanisms site-specifically in real time is an eligible but a challenging goal. Here, we elucidate the site-specific events in a red-light sensing phytochrome using the unnatural amino acid azidophenylalanine, vibrationally distinguishable from all other protein signals. In canonical phytochromes, signal transduction starts with isomerization of an excited bilin chromophore, initiating a multitude of processes in the photosensory unit of the protein, which eventually control the biochemical activity of the output domain, nanometers away from the chromophore. By implementing the label in pri…
Mechanistic insights into the phosphoryl transfer reaction in cyclin-dependent kinase 2: a QM/MM study
2019
AbstractCyclin-dependent kinase 2 (CDK2) is an important member of the CDK family exerting its most important function in the regulation of the cell cycle. It catalyzes the transfer of the gamma phosphate group from an ATP (adenosine triphosphate) molecule to a Serine/Threonine residue of a peptide substrate. Due to the importance of this enzyme, and protein kinases in general, a detailed understanding of the reaction mechanism is desired. Thus, in this work the phosphoryl transfer reaction catalyzed by CDK2 was revisited and studied by means of hybrid quantum mechanics/molecular mechanics (QM/MM) calculations. Our results show that the base-assisted mechanism is preferred over the substrat…
Determining the Geometry of Hydrogen Bonds in Solids with Picometer Accuracy by Quantum-Chemical Calculations and NMR Spectroscopy
2005
The structure of multiply hydrogen-bonded systems is determined with picometer accuracy by a combined solid-state NMR and quantum-chemical approach. On the experimental side, advanced 1H-15N dipolar recoupling NMR techniques are capable of providing proton-nitrogen distances of up to about 250 pm with an accuracy level of +/-1 pm for short distances (i.e., around 100 pm) and +/-5 pm for longer ones (i.e., 180 to 250 pm). The experiments were performed under fast magic-angle spinning, which ensures sufficient dipolar decoupling and spectral resolution of the 1H resonance lines. On the quantum-chemical side, the structures of the hydrogen-bonded systems were computationally optimised, yieldin…
Measurement of branching fractions and charge asymmetries for exclusive B decays to charmonium
2005
We report measurements of branching fractions and charge asymmetries of exclusive decays of neutral and charged B mesons into two-body final states containing a charmonium state and a light strange meson. The charmonium mesons considered are J/Psi, Psi(2S) and Chi_c1, and the light meson is either K or K*. We use a sample of about 124 million BBbar events collected with the BABAR detector at the PEP-II storage ring at the Stanford Linear Accelerator Center.
A quark model study of strong decays ofX(3915)
2017
Strong decays of are analyzed from two quark model descriptions of , a conventional one in terms of the Cornell potential and an unconventional one from a generalized screened potential. We conclude that the experimental suppression of the OZI allowed decay might be explained in both cases due to the momentum dependence of the decay amplitude. However, the experimental significance of the OZI forbidden decay could favor an unconventional description.
Operator mixing and scaling deviations in asymptotically free field theories
1976
Predictions of asymptotically free field theories for scaling deviations of the structure functions are compared with recent SLAC and Fermilab data on deep-inelastic lepton-hadron scattering. Contributions of nonsinglet as well as singlet Wilson operators are taken into account. The latter contributions are found to be non-negligible; specifically it is observed, in agreement with neutrino data, that about 60% of the proton's momentum is due to gluons. The expected quantitative pattern of scaling violations is given for a large range of ..omega.. and Q/sup 2/. (AIP)
High-Speed and Robust Monocular Tracking
2015
In this paper, we present a system for high-speed robust monocular tracking (HSRM-Tracking) of active markers. The proposed algorithm robustly and accurately tracks multiple markers at full framerate of current high-speed cameras. For this, we have developed a novel, nearly co-planar marker pattern that can be identified without initialization or incremental tracking. The pattern also encodes a unique ID to identify different markers. The individual markers are calibrated semi-automatically, thus no time-consuming and error-prone manual measurement is needed. Finally we show that the minimal spatial structure of the marker can be used to robustly avoid pose ambiguities even at large distanc…
Automatic detection and analysis of cell motility in phase-contrast time-lapse images using a combination of maximally stable extremal regions and Ka…
2013
Phase-contrast illumination is simple and most commonly used microscopic method to observe nonstained living cells. Automatic cell segmentation and motion analysis provide tools to analyze single cell motility in large cell populations. However, the challenge is to find a sophisticated method that is sufficiently accurate to generate reliable results, robust to function under the wide range of illumination conditions encountered in phase-contrast microscopy, and also computationally light for efficient analysis of large number of cells and image frames. To develop better automatic tools for analysis of low magnification phase-contrast images in time-lapse cell migration movies, we investiga…