525 research outputs found
Chiral phase boundary of QCD at finite temperature
We analyze the approach to chiral symmetry breaking in QCD at finite
temperature, using the functional renormalization group. We compute the running
gauge coupling in QCD for all temperatures and scales within a simple truncated
renormalization flow. At finite temperature, the coupling is governed by a
fixed point of the 3-dimensional theory for scales smaller than the
corresponding temperature. Chiral symmetry breaking is approached if the
running coupling drives the quark sector to criticality. We quantitatively
determine the phase boundary in the plane of temperature and number of flavors
and find good agreement with lattice results. As a generic and testable
prediction, we observe that our underlying IR fixed-point scenario leaves its
imprint in the shape of the phase boundary near the critical flavor number:
here, the scaling of the critical temperature is determined by the
zero-temperature IR critical exponent of the running coupling.Comment: 39 pages, 8 figure
Weak Phase and Strong Phase from CP Averaged and Decays
Assuming SU(3) symmetry for the strong phases in the four decay modes
B\rarrow \pi^-\pi^+, \pi^0 \pi^+, \pi^- K^+, \pi^- \bar{K}^0 and ignoring the
relative small electroweak penguin effects in those decays, the weak phase
and the strong phase can be determined in a model independent
way by the CP-averaged branching ratios of the four decay modes. It appears
that the current experimental data for and decays prefer
a negative value of . By combining with the other
constraints from , mixings and indirect
CP-violating parameter within the standard model, two favorable
solutions for the phases and are found to lie in the region:
35^{\circ}\alt\gamma\alt 62^{\circ} and 106^{\circ}\alt \delta \alt
180^{\circ} or 86^{\circ}\alt\gamma\alt 151^{\circ} and
0^{\circ}\alt\delta\alt 75^{\circ} within 1 standard deviation. It
is noted that if allowing the standard deviation of the data to be more than
1, the two solutions could approach to one solution with a much larger
region for the phases and . Direct CP asymme try
in B\rarrow \pi^-K^+ decay can be as large as
the present experimental upper bound. Direct CP asymmetry
in B\rarrow \pi^-\pi^+ decay can reach up to
about 40% at 1 level.Comment: 14 Pages, ReVTeX, 5 figures, one figure (Fig.3) is correcte
Dinâmica da matéria orgânica de um neossolo quartzarênico de cerrado convertido para cultivo em sucessão de soja e milheto
Energetic and nutrient metabolizability values of corn obtained with nutritional corrections for broilers
Energy and protein levels in diets containing phytase for broilers from 22 to 42 days of age: performance and nutrient excretion
The COMPASS Experiment at CERN
The COMPASS experiment makes use of the CERN SPS high-intensitymuon and
hadron beams for the investigation of the nucleon spin structure and the
spectroscopy of hadrons. One or more outgoing particles are detected in
coincidence with the incoming muon or hadron. A large polarized target inside a
superconducting solenoid is used for the measurements with the muon beam.
Outgoing particles are detected by a two-stage, large angle and large momentum
range spectrometer. The setup is built using several types of tracking
detectors, according to the expected incident rate, required space resolution
and the solid angle to be covered. Particle identification is achieved using a
RICH counter and both hadron and electromagnetic calorimeters. The setup has
been successfully operated from 2002 onwards using a muon beam. Data with a
hadron beam were also collected in 2004. This article describes the main
features and performances of the spectrometer in 2004; a short summary of the
2006 upgrade is also given.Comment: 84 papes, 74 figure
Dilepton mass spectra in p+p collisions at sqrt(s)= 200 GeV and the contribution from open charm
The PHENIX experiement has measured the electron-positron pair mass spectrum
from 0 to 8 GeV/c^2 in p+p collisions at sqrt(s)=200 GeV. The contributions
from light meson decays to e^+e^- pairs have been determined based on
measurements of hadron production cross sections by PHENIX. They account for
nearly all e^+e^- pairs in the mass region below 1 GeV/c^2. The e^+e^- pair
yield remaining after subtracting these contributions is dominated by
semileptonic decays of charmed hadrons correlated through flavor conservation.
Using the spectral shape predicted by PYTHIA, we estimate the charm production
cross section to be 544 +/- 39(stat) +/- 142(syst) +/- 200(model) \mu b, which
is consistent with QCD calculations and measurements of single leptons by
PHENIX.Comment: 375 authors from 57 institutions, 18 pages, 4 figures, 2 tables.
Submitted to Physics Letters B. v2 fixes technical errors in matching authors
to institutions. Plain text data tables for the points plotted in figures for
this and previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
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Measurement of Bottom versus Charm as a Function of Transverse Momentum with Electron-Hadron Correlations in p+p Collisions at sqrt(s)=200 GeV
The momentum distribution of electrons from semi-leptonic decays of charm and
bottom for mid-rapidity |y|<0.35 in p+p collisions at sqrt(s)=200 GeV is
measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC)
over the transverse momentum range 2 < p_T < 7 GeV/c. The ratio of the yield of
electrons from bottom to that from charm is presented. The ratio is determined
using partial D/D^bar --> e^{+/-} K^{-/+} X (K unidentified) reconstruction. It
is found that the yield of electrons from bottom becomes significant above 4
GeV/c in p_T. A fixed-order-plus-next-to-leading-log (FONLL) perturbative
quantum chromodynamics (pQCD) calculation agrees with the data within the
theoretical and experimental uncertainties. The extracted total bottom
production cross section at this energy is \sigma_{b\b^bar}= 3.2
^{+1.2}_{-1.1}(stat) ^{+1.4}_{-1.3}(syst) micro b.Comment: 432 authors, 6 pages text, 3 figures. Submitted to Phys. Rev. Lett.
Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Níveis de fósforo disponível e cálcio em rações suplementadas com fitase para frangos de corte nas fases de crescimento e final
Determinação da energia metabolizável e balanço de nitrogênio de dietas com diferentes teores de proteína bruta para frangos de corte
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