112,794 research outputs found
Y ( 4260 ) → γ + X ( 3872 ) in the diquarkonium picture
Get PDFThe observed Y(4260) o gamma + X(3872) decay is a natural consequence of the diquark-antidiquark description of Y and X resonances. In this note we attempt an estimate of the transition rate, Gamma_m rad, by a
non-relativistic calculation of the electric dipole term of a diquarkonium bound state. We compute Gamma_m rad for generic composition values of the isospin of X and Y. Specializing to I=0 for X(3872), we find Gamma_m rad=
496~keV for Y(4260) with I=0 and Gamma_m rad= 179~keV for I=1. Combining with BESIII data, we derive upper bounds to B(Y o J/Psi+pi+pi) and to Gamma(Y o mu^+ mu^-). We expect to confront these results with forthcoming data from electron-positron and hadron colliders
Chen, M.-J., Han, Y.-R., Hu, J.-X., Liu, Y.-J. & Huang, B. (2023) Tolypocladium rhizomatum sp. nov.: an endophytic species isolated from the rhizome of Polygonatum cyrtonema. Phytotaxa 606 (3): 201-210.
No full textChen, M.-J., Han, Y.-R., Hu, J.-X., Liu, Y.-J., Huang, B. (2023): Chen, M.-J., Han, Y.-R., Hu, J.-X., Liu, Y.-J. & Huang, B. (2023) Tolypocladium rhizomatum sp. nov.: an endophytic species isolated from the rhizome of Polygonatum cyrtonema. Phytotaxa 606 (3): 201-210. Phytotaxa 607 (1): 114-114, DOI: 10.11646/phytotaxa.607.1.10, URL: http://dx.doi.org/10.11646/phytotaxa.607.1.1
The origin of the X-ray-emitting plasma in the eastern edge of the Cygnus Loop
No full textThe Cygnus Loop is interacting with a protrusion of the cavity wall in its eastern edge (the XA region), where the X-ray emission is very bright. The complexity of the environment and the non-linear physical processes of the shock–cloud interaction make the origin of the X-ray emission still not well understood. Our purpose is to understand the physical origin of the X-ray emission in the XA region, addressing, in particular, the role of thermal conduction in the interaction process. We analysed two XMM–Newton data sets, performing image analysis and spatially resolved spectral analysis on a set of homogeneous regions. We applied a recently developed diagnostic tool to compare spectral analysis results with predictions of theoretical models, and to estimate the efficiency of thermal conduction on the X-ray-emitting shocked plasma. We found that the inhomogeneous cavity wall contains both large clumps (the protrusion) and small isolated clumps with different densities. A large indentation bent over to the south is detected. The abundance of the surrounding interstellar medium is ∼0.2 times solar value. We confirmed the important role of thermal conduction in the evolution of X-ray-emitting plasma during shock–cloud interaction
Studies of photoluminescence spectra of Cd(1-x)Mn(x)Te/Cd(1-y)Mn(y)Te diluted semiconductors superlattices with high Mn concentration
No full textThe electronic properties of Cd(1-x)Mn(x)Te/Cd(1-y)Mn(y)Te superlattices with high Mn concentration (up to 0.8) where studied by means of low and room temperature photoluminescence. The samples were grown by MBE on GaAs substrates with CdTe buffers. PL allowed the investigation of the optical emission, revealing the high quantum efficiency of the SLs
Análisis performativo del Concertino Da Camera para saxofón de Jacques Francois Antoine Ibert: digitaciones, acciones sobre la embocadura y articulación; problemas y soluciones
No full textChen, Zhiliang; director de proyecto: Bermejo Martín, Carlos2021-2022Máster Universitario en Interpretación Musical e Investigación PerformativaFacultad de Música y Artes Escénica
INNOVATIVE PILLAR[6]ARENE-BASED STATIONARY PHASES FOR HIGH-RESOLUTION GAS CHROMATOGRAPHIC ANALYSES
No full textIn this work, the synthesis, fabrication, and characterization of new stationary phases based on pillar[6]arene derivative modified by long alkyl chains (P6A-C10) for high-resolution gas chromatographic (GC) analyses are reported. Pillar[n]arenes are a new class of macrocyclic hosts that can accommodate specific guests due to their highly symmetrical and rigid pillar architectures with π-electron rich cavities. Quantum chemistry calculations have been performed, showing a difference in non-covalent interactions with the P6A-C10 pillar framework, which leads to specific selectivity for aromatic compounds. The GC columns prepared with these innovative stationary phases exhibited a medium polarity, and good reproducibility for run-to-run, day-to-day, and column-to-column analyses [1], demonstrating great potential as new stationary phases in separation science. Furthermore, peculiar advantages are achieved if compared with the commercial HP-5, HP-35, DB-17, and PEG-20M columns, showing unmatched resolving capabilities toward chloroaniline, bromoaniline, iodoaniline, toluidine, and xylene isomers [2].
References:
1. Sun, T., Chen, R., Huang, Q., Ba, M., Cai, Z., Hu, S., Liu, X., Nardiello, D., & Quinto, M., ACS Appl. Mater. Interfaces 14 (2022) 56132−56142.
2. Sun, T., Chen, R., Huang, Q., Ba, M., Cai, Z., Chen, H., Qi, Y., Chen, H., Liu, X., Nardiello, D., & Quinto, M., Anal. Chim. Acta 1251 (2023) 340979
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M-estimator, and D-optimality model construction using orthogonal forward regression
No full textThis correspondence introduces a new orthogonal forward regression (OFR) model identification algorithm using D-optimality for model structure selection and is based on an M-estimators of parameter estimates. M-estimator is a classical robust parameter estimation technique to tackle bad data conditions such as outliers. Computationally, The M-estimator can be derived using an iterative reweighted least squares (IRLS) algorithm. D-optimality is a model structure robustness criterion in experimental design to tackle ill-conditioning in model Structure. The orthogonal forward regression (OFR), often based on the modified Gram-Schmidt procedure, is an efficient method incorporating structure selection and parameter estimation simultaneously. The basic idea of the proposed approach is to incorporate an IRLS inner loop into the modified Gram-Schmidt procedure. In this manner, the OFR algorithm for parsimonious model structure determination is extended to bad data conditions with improved performance via the derivation of parameter M-estimators with inherent robustness to outliers. Numerical examples are included to demonstrate the effectiveness of the proposed algorithm
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
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