287 research outputs found
Exotic mesons from quantum chromodynamics with improved gluon and quark actions on the anisotropic lattice
Hybrid (exotic) mesons, which are important predictions of quantum
chromodynamics (QCD), are states of quarks and anti-quarks bound by excited
gluons. First principle lattice study of such states would help us understand
the role of ``dynamical'' color in low energy QCD and provide valuable
information for experimental search for these new particles. In this paper, we
apply both improved gluon and quark actions to the hybrid mesons, which might
be much more efficient than the previous works in reducing lattice spacing
error and finite volume effect. Quenched simulations were done at
and on a anisotropic lattice using our PC cluster. We
obtain MeV for the mass of the hybrid meson
in the light quark sector, and Mev in the
charm quark sector; the mass splitting between the hybrid meson in the charm quark sector and the spin averaged S-wave charmonium mass
is estimated to be MeV. As a byproduct, we obtain MeV for the mass of a P-wave or
meson and MeV for the mass of a P-wave meson, which are comparable to their experimental value 1426 MeV for the
meson. The first error is statistical, and the second one is
systematical. The mixing of the hybrid meson with a four quark state is also
discussed.Comment: 12 pages, 3 figures. Published versio
Observación confirmada de Oxalis dillenii en España
We confirm the presence of Oxalis dillenii Jacq. in the Catalonian province Lleida (Catalonia, Spain). Identification was confirmed morphologically and through DNA barcode sequencing. A map of the distribution of O. dillenii is supplied, as are notes on its identification.Confirmamos la presencia de Oxalis dillenii Jacq. en la provincia de Lérida (Cataluña, España). La identidad de la especie fue confirmada tanto por sus características morfológicas como a través de la secuenciación del código de barras del ADN. Se proporciona un mapa de distribución de O. dillenii, así como notas sobre su identificación
The CP-violating asymmetry in \eta\to\pi^+ \pi^- e^+e^-
We study the CP-violating asymmetry {\cal A}_{\rm CP}, which arises, in
\eta\to\pi^+\pi^- e^+e^-, from the angular correlation of the e^+ e^- and
\pi^+\pi^- planes due to the interference between the magnetic and electric
decay amplitudes. With the phenomenologically determined magnetic amplitude and
branching ratio as input, the asymmetry, induced by the electric bremsstrahlung
amplitude through the CP-violating decay \eta\to\pi^+\pi^-, and by an
unconventional tensor type operator, has been estimated respectively. The upper
bound of {\cal A}_{\rm CP} from the former is about 10^{-3}, and the asymmetry
from the latter might be up to O(10^{-2}). One can therefore expect that this
CP asymmetry would be an interesting CP-violating observable for the future
precise measurements in the \eta factories.Comment: LaTeX, 6 pages. One reference corrected, and some new references
adde
Quark and Lepton Mass Patterns and the Absolute Neutrino Mass Scale
We investigate what could be learned about the absolute scale of neutrino
masses from comparisons among the patterns within quark and lepton mass
hierarchies. First, we observe that the existing information on neutrino masses
fits quite well to the unexplained, but apparently present regularities in the
quark and charged lepton sectors. Second, we discuss several possible mass
patterns, pointing out that this quite generally leads towards hierarchical
neutrino mass patterns especially disfavoring the vacuum solution.Comment: final version to be published in PRD, 5 pages, 2 figures, RevTe
Unknowns after the SNO Charged-Current Measurement
We perform a model-independent analysis of solar neutrino flux rates
including the recent charged-current measurement at the Sudbury Neutrino
Observatory (SNO). We derive a universal sum rule involving SNO and
SuperKamiokande rates, and show that the SNO neutral-current measurement can
not fix the fraction of solar oscillating to sterile neutrinos. The
large uncertainty in the SSM B flux impedes a determination of the sterile
neutrino fraction.Comment: Version to appear in PRL; includes analysis with anticipated SNO NC
measuremen
Axial vector form factor of nucleons in a light-cone diquark model
The nucleon axial vector form factor is investigated in a light-cone quark
spectator diquark model, in which Melosh rotations are applied to both the
quark and vector diquark. It is found that this model gives a very good
description of available experimental data and the results have very little
dependence on the parameters of the model. The relation between the nucleon
axial constant and the anomalous magnetic moment of nucleons is also discussed.Comment: 8 pages, Revtex4, 1 figure, version to be published in Phys. Rev.
Quark model predictions for photoproduction on the proton
The photoproduction of vector mesons is investigated in a quark model
with an effective Lagrangian. Including both baryon resonance excitations and
{\it t}-channel exchanges, observables for the reactions and are predicted, using the
SU(3)-flavor-blind assumption of non-perturbative QCD.Comment: Revtex, 3 eps figures, revised version accepted by PRC Rapid Comm
Study of color connections in annihilation
We replace in the event generator JETSET the color singlet chain connection
with the color separate state one as the interface between the hard and soft
sectors of hadronic processes. The modified generator is applied to produce the
hadronic events in annihilation. It describes the experimental data
at the same level as the original JETSET with default parameters. This should
be understood as a demonstration that color singlet chain is not the unique
color connection. We also search for the difference in special sets of
three-jet events arising from different color connections, which could subject
to further experimental test.Comment: 23 pages, 8 figures, 4 tables, Revtex
Differences in Technical Performance of Players From ‘The Big Five’ European Football Leagues in the UEFA Champions League
The current study aimed to identify the differences in technical performance between players from clubs of Bundesliga (Germany), La Liga (Spain), Ligue 1 (France), Premier League (England) and Serie A (Italy) when competing in the matches of the UEFA Champions League. Technical performance-related match data of 1,291 players from 1,125 matches (9,799 observations) of the UEFA Champions League (seasons 2009/2010–2017/2018) were collected and analysed. The generalised mixed linear modelling was employed taking the names of the league as the independent variable to predict the count number of 20 technical performance-related match actions and events performed by players belonging to different leagues. The non-clinical magnitude-based inference was used to evaluate the uncertainty in the true effects of the predictor. Results showed that differences in the technical performances between players from La Liga, Premier League and Ligue 1 were all trivial. Bundesliga players made higher numbers of shots than players from La Liga, Premier League and Serie A and achieved more long balls than players from Ligue 1. Serie A players achieved lower numbers of ball touches, passes and lower pass accuracy per match than players from any of the other four leagues. In addition, players from Serie A performed a higher number of long balls per match than Ligue 1 players and lower number of dribbles per match than Premier League players. Non-significant differences in other variables related to passing and organising and all variables related to defending were identified in players between the five leagues. The identified differences in technical performance among leagues could provide a more thorough understanding for practitioners working within the fields of talent identification, player development, player recruitment, coaching and match preparation
Active neutrino Oscillations and the SNO neutral Current measurement
We discuss the relation between the observed CC, ES, and NC fluxes with the
flavor fractional content of the solar neutrino flux seen by SNO. By using
existing estimates of the cross sections for the charged and neutral current
reactions which take into account the detector resolution, we show how the
forthcoming SNO rates unconstrained by the standard B shape could test the
oscillations into active states. We perform a model independent analysis for
the Super-K and SNO data, assuming a non distorted spectrum.Comment: 6pages, 4 figure
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