82 research outputs found
Measurement of azimuthal asymmetries in inclusive charged dipion production in annihilations at = 3.65 GeV
We present a measurement of the azimuthal asymmetries of two charged pions in
the inclusive process based on a data set of 62
at the center-of-mass energy GeV collected with
the BESIII detector. These asymmetries can be attributed to the Collins
fragmentation function. We observe a nonzero asymmetry, which increases with
increasing pion momentum. As our energy scale is close to that of the existing
semi-inclusive deep inelastic scattering experimental data, the measured
asymmetries are important inputs for the global analysis of extracting the
quark transversity distribution inside the nucleon and are valuable to explore
the energy evolution of the spin-dependent fragmentation function.Comment: 7 pages, 5 figure
Measurement of the Cross Section between 600 and 900 MeV Using Initial State Radiation
We extract the cross section in the energy
range between 600 and 900 MeV, exploiting the method of initial state
radiation. A data set with an integrated luminosity of 2.93 fb taken at
a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII
collider is used. The cross section is measured with a systematic uncertainty
of 0.9%. We extract the pion form factor as well as the
contribution of the measured cross section to the leading order hadronic vacuum
polarization contribution to . We find this value to be
.Comment: 14 pages, 7 figures, accepted by PL
Measurements of absolute hadronic branching fractions of baryon
Using of collisions recorded at
with the BESIII detector, we report first measurements
of absolute hadronic branching fractions of Cabibbo-favored decays of the
baryon with a double-tag technique. A global least-square
fitter is utilized to improve the measured precision. Among the measurements
for twelve decay modes, the branching fraction for
is determined to be
, where the first uncertainty is statistical and the
second is systematic. In addition, the measurements of the branching fractions
of the other eleven Cabbibo-favored hadronic decay modes are significantly
improved
Observation of near = 4.42 and 4.6 GeV
Based on data samples collected with the BESIII detector operating at the
BEPCII storage ring at center-of-mass energies 4.4 GeV, the
processes are observed for the first
time. With an integrated luminosity of near 4.42
GeV, a significant signal is found, and the cross section is
measured to be (20.9 \pm 3.2 \pm 2.5)\pb. With near 4.6 GeV, a clear signal is seen, and the cross section is
measured to be (9.5 \pm 2.1 \pm 1.3) \pb, while evidence is found for an
signal. The first errors are statistical and the second are
systematic. Due to low luminosity or low cross section at other energies, no
significant signals are observed. In the cross section, an
enhancement is seen around 4.42 GeV. Fitting the cross section
with a coherent sum of the Breit-Wigner function and a phase space
term, the branching fraction is
obtained to be of the order of .Comment: 7 pages, 3 figure
Measurement of the Matrix Elements for the Decays and
Based on a sample of events collected with the
BESIII detector at the BEPCII collider, Dalitz plot analyses of selected 79,625
events, 33,908
events and 1,888
events are performed. The measured
matrix elements of are in reasonable agreement
with previous measurements. The Dalitz plot slope parameters of
and
are determined to be and , respectively, where the first uncertainties are statistical and the
second systematic. Both values are consistent with previous measurements, while
the precision of the latter one is improved by a factor of three. Final state
interactions are found to have an important role in those decays.Comment: 12 pages, 7 figure
An amplitude analysis of the system produced in radiative decays
An amplitude analysis of the system produced in radiative
decays is presented. In particular, a piecewise function that
describes the dynamics of the system is determined as a
function of from an analysis of the
decays collected by the BESIII detector.
The goal of this analysis is to provide a description of the scalar and tensor
components of the system while making minimal assumptions about
the properties or number of poles in the amplitude. Such a model-independent
description allows one to integrate these results with other related results
from complementary reactions in the development of phenomenological models,
which can then be used to directly fit experimental data to obtain parameters
of interest. The branching fraction of is
determined to be , where the uncertainty is
systematic only and the statistical uncertainty is negligible.Comment: Submitted to Phys. Rev. D 19 pages, 4 figure
Measurement of the branching fractions of and in
We study decays to final states involving the with a
482pb data sample collected at = 4.009GeV with the
\mbox{BESIII} detector at the BEPCII collider. We measure the branching
fractions = (8.81.80.5)
and = ()
where the first uncertainty is statistical and the second is systematic. In
addition, we estimate an upper limit on the non-resonant branching ratio
at the 90
confidence level. Our results are consistent with CLEO's recent measurements
and help to resolve the disagreement between the theoretical prediction and
CLEO's previous measurement of
Measurement of the leptonic decay width of using initial state radiation
Using a data set of 2.93 fb taken at a center-of-mass energy of
= 3.773 GeV with the BESIII detector at the BEPCII collider, we
measure the process and determine the product of the branching fraction and the
electronic width ~eV. Using the earlier-published BESIII result for
= (5.973 0.007 0.037)\%, we derive the electronic width ~= (5.58
0.05 0.08) keV.Comment: 8 pages, 2 figure
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