44 research outputs found
A Global Treatment Of VMD Physics Up To The : I. Annihilations, Anomalies And Vector Meson Partial Widths
The HLS Model, equipped with a mechanism providing the breaking of U(3)/SU(3)
symmetry and an isospin symmetry breaking leading naturally to vector meson
mixing, has been recently shown to successfully account for e^+ e^- \ra
\pi^+\pi^- cross section and for the dipion spectrum in decay. The
present study shows that the full anomalous sector of the HLS model can be
considered and is validated by the experimental data. Indeed, this extended
model provides a successful simultaneous fit to the e^+ e^- \ra \pi^+\pi^-
data together with the available data on e^+ e^- \ra \pi^0\gamma, e^+ e^-
\ra \eta\gamma and e^+ e^- \ra \pi^0 \pi^+\pi^- cross sections. It is shown
that the fit of these data sets also predicts an accurate description of the
\eta/\eta^\prime \ra \pi^+ \pi^- \gamma decays fully consistent with the
reported information on their branching fractions and spectra. Finally, one
also derives from our global fits products of widths of the form \Gamma (V \ra
f_1)\Gamma(V \ra e^+ e^-) and ratios of the form \Gamma (V \ra f_1)/\Gamma
(V \ra f_2) describing decays of vector mesons to several non--leptonic final
states.Comment: 58 pages, 10 figures Corrected a few misprints. Footnote 10 change
A Global Treatment Of VMD Physics Up To The : I. Annihilations, Anomalies And Vector Meson Partial Widths
The HLS Model, equipped with a mechanism providing the breaking of U(3)/SU(3)
symmetry and an isospin symmetry breaking leading naturally to vector meson
mixing, has been recently shown to successfully account for e^+ e^- \ra
\pi^+\pi^- cross section and for the dipion spectrum in decay. The
present study shows that the full anomalous sector of the HLS model can be
considered and is validated by the experimental data. Indeed, this extended
model provides a successful simultaneous fit to the e^+ e^- \ra \pi^+\pi^-
data together with the available data on e^+ e^- \ra \pi^0\gamma, e^+ e^-
\ra \eta\gamma and e^+ e^- \ra \pi^0 \pi^+\pi^- cross sections. It is shown
that the fit of these data sets also predicts an accurate description of the
\eta/\eta^\prime \ra \pi^+ \pi^- \gamma decays fully consistent with the
reported information on their branching fractions and spectra. Finally, one
also derives from our global fits products of widths of the form \Gamma (V \ra
f_1)\Gamma(V \ra e^+ e^-) and ratios of the form \Gamma (V \ra f_1)/\Gamma
(V \ra f_2) describing decays of vector mesons to several non--leptonic final
states.Comment: 58 pages, 10 figures Corrected a few misprints. Footnote 10 change
VMD, the WZW Lagrangian and ChPT: The Third Mixing Angle
We show that the Hidden Local Symmetry Model, supplemented with well-known
procedures for breaking flavor SU(3) and nonet symmetry, provides all the
information contained in the standard Chiral Perturbation Theory (ChPT)
Lagrangian . This allows to rely on radiative
decays of light mesons ( and ) in order to extract
some numerical information of relevance to ChPT: a value for , a quark mass ratio of , and a negligible
departure from the Gell-Mann--Okubo mass formula. The mixing angles are
and . We also give the values of all decay constants. It is shown that
the common mixing pattern with one mixing angle is actually quite
appropriate and algebraically related to the mixing pattern
presently preferred by the ChPT community. For instance the traditional
is functionally related to the ChPT and fulfills
. The vanishing of , supported by all
data on radiative decays, gives a novel relation between mixing angles and the
violation of nonet symmetry in the pseudoscalar sector. Finally, it is shown
that the interplay of nonet symmetry breaking through U(3) \ra SU(3)
U(1) satisfies all requirements of the physics of radiative decays without any
need for additional glueballs.Comment: 31 pages, 1 figur
Multi-frame Packet Reservation Multiple Access Using Oscillation-scaled Histogram-based Markov Modelling of Video Codecs
A model is proposed for replacing the video codec in networking studies, which is tested for sources with a mean bitrate in the range of 10Kb/s to 10Mb/s. The standard frame sizes investigated are the International Telecommunications Union's (ITU) 352 x 288-pixel Common Intermediate Format (CIF), 176 x 144-pixel Quarter CIF (QCIF), 704 x 576-pixel 4CIF and 128 x 96-pixel Sub-QCIF (SQCIF). The proposed 20-state 'oscillation-scaled’ Markov model was found to represent the relevant video codec characteristics adequately. The performance of this model is then tested in the context of a novel Multi-frame Packet Reservation Multiple Access or MF-PRMA scheme, which is shown in Figure 17 to outperform conventional PRMA in terms of both its delay and packet dropping performance, reaching throughput values as high as 79%
A Global Treatment Of VMD Physics Up To The phi: II. tau Decay and Hadronic Contributions To g-2
Relying on the Hidden Local Symmetry (HLS) model equipped with a mechanism
breaking the U(3)/SU(3)/SU(2) symmetries and generating a dynamical vector
meson mixing, it has been shown that a global fit successfully describes the
cross sections for the e+ e- -> pi+ pi-, e+ e- -> (pi0/eta) gamma and e+ e- ->
pi0 pi+ pi- annihilation channels. One extends this global fit in order to
include also the dipion spectra from the tau decay, taking into account all
reported information on their statistical and systematic errors. A model
accounting for lineshape distortions of the rho+- spectrum relative to rho0 is
also examined when analyzing the tau data behavior within the global fit
framework. One shows that a successful account for e+ e- annihilation data and
tau spectra can be simultaneously reached. Then, issues related with
non--perturbative hadronic contributions to the muon g-2 are examined in
details. It is shown that all e+ e- data considered together allow for improved
and motivated estimates for the a_mu(pi+ pi-), the pi+ pi- loop contribution to
the muon g-2; for instance, integrated between 0.630 and 0.958 GeV, we find
a_mu(pi+ pi-)= 359.62 +- 1.62 (in units of 10^{-10}), a 40% improvement of the
current uncertainty. The effects of the various tau samples in the context of a
global fit procedure leads to conclude that different lineshape distortions are
revealed by the ALEPH, BELLE and CLEO data samples. Relying on global fits to
the data quoted above, one also provides motivated estimates of the pi+ pi-,
pi0 gamma, eta gamma and pi0 pi+ pi- contributions to a_mu up to 1 GeV with the
smallest possible uncertainties. These estimates are based on various global
fit configurations, each yielding a good probability.Comment: 43 pages, scope enlarged, model extended, same conclusions. Accepted
for publication in EPJ-
Rich Reconstruction and particle identification using ring fit methods: Standalone PID in the Rich2 detector
We have extended the ring fit algorithm presented in earlier works, in order to transform it into a fully standalone PID algorithm running over the full RICH2 momentum range. For this purpose, the full information provided by the tracking (track direction and momentum as well as their errors) is accounted for in the minimized chi squared function along with the photon information. Additionally, all available information concerning the Cerenkov light emission effect is accounted for in the PID algorithm. PID efficiencies and misidentification rates are found similar to the global ID results, while the statistical information is still much more reliable
The Pion Form Factor Within the Hidden Local Symmetry Model
We analyze a pion form factor formulation which fulfills the Analyticity requirement within the Hidden Local Symmetry (HLS) Model. We show that it implies an --dependent dressing of the VMD coupling and an account of several coupled channels. The corresponding function provides nice fits of the pion form factor data from to GeV. It is shown that the coupling to has little effects, while \omg \pi^0 improves significantly the fit quality below the mass. All parameters, except for the subtraction polynomial coefficients are fixed from the rest of the HLS phenomenology. The fits show consistency with the expected behaviour of at up to and with the phase shift data on from threshold to somewhat above the mass. The \omg sector is also examined in relation with recent data from CMD--2.We analyze a pion form factor formulation which fulfills the Analyticity requirement within the Hidden Local Symmetry (HLS) Model. We show that it implies an --dependent dressing of the VMD coupling and an account of several coupled channels. The corresponding function provides nice fits of the pion form factor data from to GeV. It is shown that the coupling to has little effects, while \omg \pi^0 improves significantly the fit quality below the mass. All parameters, except for the subtraction polynomial coefficients are fixed from the rest of the HLS phenomenology. The fits show consistency with the expected behaviour of at up to and with the phase shift data on from threshold to somewhat above the mass. The \omg sector is also examined in relation with recent data from CMD-2.We analyze a pion form factor formulation which fulfills the Analyticity requirement within the Hidden Local Symmetry (HLS) Model. We show that it implies an --dependent dressing of the VMD coupling and an account of several coupled channels. The corresponding function provides nice fits of the pion form factor data from to GeV. It is shown that the coupling to has little effects, while \omg \pi^0 improves significantly the fit quality below the mass. All parameters, except for the subtraction polynomial coefficients are fixed from the rest of the HLS phenomenology. The fits show consistency with the expected behaviour of at up to and with the phase shift data on from threshold to somewhat above the mass. The \omg sector is also examined in relation with recent data from CMD-2.We analyze a pion form factor formulation which fulfills the Analyticity requirement within the Hidden Local Symmetry (HLS) Model. We show that it implies an --dependent dressing of the VMD coupling and an account of several coupled channels. The corresponding function provides nice fits of the pion form factor data from to GeV. It is shown that the coupling to has little effects, while improves significantly the fit quality below the mass. All parameters, except for the subtraction polynomial coefficients are fixed from the rest of the HLS phenomenology. The fits show consistency with the expected behaviour of at up to and with the phase shift data on from threshold to somewhat above the mass. The sector is also examined in relation with recent data from CMD-2
DMSO removal reduces stem-cell infusion-related toxicity and allows excellent engraftment of cryopreserved unrelated cord blood and autologous stem cells
UNIFESP, GRAACC, Pediat Oncol Inst, São Paulo, BrazilUniversidade Federal de São Paulo, São Paulo, BrazilUNIFESP, GRAACC, Pediat Oncol Inst, São Paulo, BrazilUniversidade Federal de São Paulo, São Paulo, BrazilWeb of Scienc
Large volume leukapheresis for autologous peripheral blood stem cell collection in children weighting less than 25 kg
Universidade Federal de São Paulo, GRAACC, Pediat Oncol Inst, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pathol, São Paulo, BrazilUniversidade Federal de São Paulo, GRAACC, Pediat Oncol Inst, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pathol, São Paulo, BrazilWeb of Scienc
The Dipion Mass Spectrum In e+e- Annihilation and tau Decay: A Dynamical (rho0, omega, phi) Mixing Approach
We readdress the problem of finding a simultaneous description of the pion
form factor data in e+e- annihilations and in tau decays. For this purpose, we
work in the framework of the Hidden Local Symmetry (HLS) Lagrangian and modify
the vector meson mass term by including the pion and kaon loop contributions.
This leads us to define the physical rho, omega and phi fields as linear
combinations of their ideal partners, with coefficients being meromorphic
functions of s, the square of the 4--momentum flowing into the vector meson
lines. This allows us to define a dynamical, i.e. s-dependent, vector meson
mixing scheme. The model is overconstrained by extending the framework in order
to include the description of all meson radiative (V P gamma and P gamma gamma
couplings) and leptonic (Ve+e- couplings) decays and also the isospin breaking
(omega/ phi --> pi+ pi-) decay modes. The model provides a simultaneous,
consistent and good description of the e+e- and tau dipion spectra. The
expression for pion form factor in the latter case is derived from those in the
former case by switching off the isospin breaking effects specific to e+e- and
switching on those for tau decays. Besides, the model also provides a good
account of all decay modes of the form V P gamma, Pgamma gamma as well as the
isospin breaking decay modes. It leads us to propose new reference values for
the rho^0 --> e+ e- and omega --> pi+ pi- partial widths which are part of our
description of the pion form factor. Other topics (phi --> K anti K, the rho
meson mass and width parameters) are briefly discussed. Therefore, we confirm
the 3.3 sigma discrepancy between the theoretical estimate of a_mu based on
e+e- and its direct BNL measurement.Comment: 71 pages, 8 figures. Accepted by EPJ C. Version 3: correct minor
typos, minor changes spread out into the text. Extension of Sections 12.2 and
12.3.5 and introduction of the new Appendix