4,655 research outputs found
Averages of b-hadron Properties at the End of 2005
This article reports world averages for measurements on b-hadron properties
obtained by the Heavy Flavor Averaging Group (HFAG) using the available results
as of at the end of 2005. In the averaging, the input parameters used in the
various analyses are adjusted (rescaled) to common values, and all known
correlations are taken into account. The averages include lifetimes, neutral
meson mixing parameters, parameters of semileptonic decays, branching fractions
of B meson decays to final states with open charm, charmonium and no charm, and
measurements related to CP asymmetries
Competing electric and magnetic excitations in backward electron scattering from heavy deformed nuclei
Important contributions to the cross sections of
low-lying orbital excitations are found in heavy deformed nuclei, arising
from the small energy separation between the two excitations with and 1, respectively. They are studied microscopically in QRPA using
DWBA. The accompanying response is negligible at small momentum transfer
but contributes substantially to the cross sections measured at for fm ( MeV)
and leads to a very good agreement with experiment. The electric response is of
longitudinal type for but becomes almost purely
transverse for larger backward angles. The transverse response
remains comparable with the response for fm
( MeV) and even dominant for MeV. This happens even at
large backward angles , where the dominance is
limited to the lower region.Comment: RevTeX, 19 pages, 8 figures included Accepted for publication in Phys
Rev
Averages of -hadron, -hadron, and -lepton properties as of summer 2014
This article reports world averages of measurements of -hadron,
-hadron, and -lepton properties obtained by the Heavy Flavor Averaging
Group (HFAG) using results available through summer 2014. For the averaging,
common input parameters used in the various analyses are adjusted (rescaled) to
common values, and known correlations are taken into account. The averages
include branching fractions, lifetimes, neutral meson mixing parameters,
violation parameters, parameters of semileptonic decays and CKM matrix
elements.Comment: 436 pages, many figures and tables. Online updates available at
http://www.slac.stanford.edu/xorg/hfag
High-energy scissors mode
All the orbital M1 excitations, at both low and high energies, obtained from
a rotationally invariant QRPA, represent the fragmented scissors mode. The
high-energy M1 strength is almost purely orbital and resides in the region of
the isovector giant quadrupole resonance. In heavy deformed nuclei the
high-energy scissors mode is strongly fragmented between 17 and 25 MeV (with
uncertainties arising from the poor knowledge of the isovector potential). The
coherent scissors motion is hindered by the fragmentation and for single transitions in this region. The cross
sections for excitations above 17 MeV are one order of magnitude larger for E2
than for M1 excitations even at backward angles.Comment: 20 pages in RevTEX, 5 figures (uuencoded,put with 'figures') accepted
for publication in Phys.Rev.
Search for decays to invisible final states at Belle
We report a search for decays into invisible final states using a
data sample of pairs collected at the
resonance with the Belle detector at the KEKB
collider. The signal is identified by fully reconstructing a hadronic decay of
the accompanying meson and requiring no other particles in the event. No
significant signal is observed, and we obtain an upper limit of at the 90% confidence level for the branching fraction of invisible
decay.Comment: 6 pages, 5 figures (9 figure files
Measurements of the and resonances via
We report new measurements of the total cross sections for ( = 1, 2, 3) and from a
high-luminosity fine scan of the region - GeV with the
Belle detector. We observe that the spectra have
little or no non-resonant component and extract from them the masses and widths
of and and their relative phase. We find
MeV/ and
\Gamma_{10860}=(53.7^{+7.1}_{-5.6}\,^{+1.3}_{-5.4}) MeV and report first
measurements M_{11020}=(10987.5^{+6.4}_{-2.5}\,^{+9.0}_{-2.1}) MeV/,
\Gamma_{11020}=(61^{+9}_{-19}\,^{+2}_{-20}) MeV, and \phi_{\rm
11020}-\phi_{\rm 10860} = (-1.0\pm0.4\,^{+1.4}_{-0.1}) rad.Comment: University of Cincinnati preprint UCHEP-15-01, submitted to Physical
Review D - Rapid Communication
Observation of
We report the first observation of the decays . The data sample of fb used in this analysis corresponds
to million pairs, collected at the resonance by
the Belle detector at the KEKB asymmetric-energy collider. We
observe and excesses of events for the two decay
modes and measure the branching fractions of and to be
and ,
respectively, where the first uncertainties are statistical and the second are
systematic. These results are not compatible with the predictions based on the
generalized factorization approach. In addition, a threshold enhancement in the
di-baryon () system is observed, consistent with that observed
in similar decays.Comment: 16 pages, 3 figures and 3 tables, submitted to PR
Evidence for B- -> Ds+ K- l- nubar and search for B- -> Ds*+ K- l- nubar
We report measurements of the decays B- -> Ds(*)+ K- l- nubar in a data
sample containing 657x10^6 BBbar pairs collected with the Belle detector at the
KEKB asymmetric-energy e+e- collider. We observe a signal with a significance
of 6 sigma for the combined Ds and Ds* modes and find the first evidence of the
B- -> Ds+ K- l- nubar decay with a significance of 3.4 sigma. We measure the
following branching fractions: BF(B- -> Ds+ K- l nubar) = (0.30 +/- 0.09(stat)
+0.11 -0.08(syst)) x 10^-3 and BF(B- -> Ds*+ K- l- nubar) = (0.59 +/-
0.12(stat) +/- 0.15(syst)) x 10^-3 and set an upper limit BF(B- -> Ds*+ K- l-
nubar) < 0.56 x 10^-3 at the 90% confidence level. We also present the first
measurement of the Ds+K- invariant mass distribution in these decays, which is
dominated by a prominent peak around 2.6 GeV/c^2.Comment: Submitted to Phys. Rev.
Inclusive cross sections for pairs of identified light charged hadrons and for single protons in at 10.58 GeV
We report the first double differential cross sections of two charged pions
and kaons () in electron-positron annihilation as a
function of the fractional energies of the two hadrons for any charge and
hadron combination. The dependence of these di-hadron cross sections on the
topology (same, opposite-hemisphere or anywhere) is also studied with the help
of the event shape variable thrust and its axis. The ratios of these di-hadron
cross sections for different charges and hadron combinations directly shed
light on the contributing fragmentation functions. For example, we find that
the ratio of same-sign pion pairs over opposite-sign pion pairs drops toward
higher fractional energies where disfavored fragmentation is expected to be
suppressed. These di-hadron results are obtained from a
data sample collected near the resonance with the Belle detector
at the KEKB asymmetric-energy collider. Extending the previously
published single-pion and single-kaon cross sections, single-proton () cross sections are extracted from a data
sub-sample.Comment: submitted to PR
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