30,258 research outputs found
The NLO QCD Corrections to Meson Production in Decays
The decay width of to meson is evaluated at the next-to-leading
order(NLO) accuracy in strong interaction. Numerical calculation shows that the
NLO correction to this process is remarkable. The quantum
chromodynamics(QCD)renormalization scale dependence of the results is obviously
depressed, and hence the uncertainties lying in the leading order calculation
are reduced.Comment: 14 pages, 7 figures; references added; expressions and typos ammende
Boson Decays to Meson and Its Uncertainties
The programming new collider with high luminosity shall provide
another useful platform to study the properties of the doubly heavy meson
in addition to the hadronic colliders as LHC and TEVATRON. Under the `New Trace
Amplitude Approach', we calculate the production of the spin-singlet and
the spin-triplet mesons through the boson decays, where
uncertainties for the production are also discussed. Our results show
KeV and
KeV, where the errors are caused by
varying and within their reasonable regions.Comment: 11 pages, 5 figures, 2 tables. To be published in Eur.Phys.J.
Production of the -Wave Excited -States through the Boson Decays
In Ref.[7],we have dealt with the production of the two color-singlet
-wave -quarkonium states and
through the boson decays. As an
important sequential work, we make a further discussion on the production of
the more complicated -wave excited -quarkonium states, i.e.
and (with
). More over, we also calculate the channel with the two color-octet
quarkonium states and , whose contributions to the decay width maybe at the same order of
magnitude as that of the color-singlet -wave states according to the naive
nonrelativistic quantum chromodynamics scaling rules. The -wave states shall
provide sizable contributions to the production, whose decay width is
about 20% of the total decay width . After summing up all
the mentioned -quarkonium states' contributions, we obtain
KeV, where the errors are caused
by the main uncertainty sources.Comment: 8 pages, 5 figures and 2 tables. basic formulae in the appendix are
cut off to match the published version, which can be found in v1. to be
published in Eur.Phys.J.
Anomalous physical properties of underdoped weak-ferromagnetic superconductor RuSrEuCuO
Similar to the optimal-doped, weak-ferromagnetic (WFM induced by canted
antiferromagnetism, T = 131 K) and superconducting (T = 56 K)
RuSrGdCuO, the underdoped RuSrEuCuO
(T = 133 K, T = 36 K) also exhibited a spontaneous vortex state
(SVS) between 16 K and 36 K. The low field (20 G) superconducting
hysteresis loop indicates a weak and narrow Meissner state region of average
lower critical field B(T) = B(0)[1 -
(T/T)], with B(0) = 7 G and T = 16 K. The
vortex melting transition (T = 21 K) below T obtained from
the broad resistivity drop and the onset of diamagnetic signal indicates a
vortex liquid region due to the coexistence and interplay between
superconductivity and WFM order. No visible jump in specific heat was observed
near T for Eu- and Gd-compound. This is not surprising, since the
electronic specific heat is easily overshadowed by the large phonon and
weak-ferromagnetic contributions. Furthermore, a broad resistivity transition
due to low vortex melting temperature would also lead to a correspondingly
reduced height of any specific heat jump. Finally, with the baseline from the
nonmagnetic Eu-compound, specific heat data analysis confirms the magnetic
entropy associated with antiferromagnetic ordering of Gd (J = S = 7/2)
at 2.5 K to be close to ln8 as expected.Comment: 7 figure
Doubly heavy baryon production at polarized photon collider
We study the inclusive production of doubly heavy baryon at
polarized photon collider. Our results show that proper choice of the initial
beam polarizations may increase the production rate of approximately
10%.Comment: 9 pages, 5 figure
The Decays to -wave Charmonium by Improved Bethe-Salpeter Approach
We re-calculate the exclusive semileptonic and nonleptonic decays of
meson to a -wave charmonium in terms of the improved Bethe-Salpeter (B-S)
approach, which is developed recently. Here the widths for the exclusive
semileptonic and nonleptonic decays, the form factors, and the charged lepton
spectrums for the semileptonic decays are precisely calculated. To test the
concerned approach by comparing with experimental measurements when the
experimental data are available, and to have comparisons with the other
approaches the results obtained by the approach and those by some approaches
else as well as the original B-S approach, which appeared in literature, are
comparatively presented and discussed.Comment: 33 pages, 5 figures, 3 table
Experimental evidence for a two-gap structure of superconducting NbSe_2: a specific heat study in external magnetic fields
To resolve the discrepancies of the superconducting order parameter in
quasi-two-dimensional NbSe_2, comprehensive specific-heat measurements have
been carried out. By analyzing both the zero-field and mixed-state data with
magnetic fields perpendicular to and parallel to the c axis of the crystal and
using the two-gap model, we conclude that (1) more than one energy scale of the
order parameter is required for superconducting NbSe_2 due to the thermodynamic
consistency; (2)delta_L=1.26 meV and delta_S=0.73 meV are obtained; (3)
N_S(0)/N(0)=11%~20%; (4) The observation of the kink in gamma(H) curve suggests
that the two-gap scenario is more favorable than the anisotropic s-wave model
to describe the gap structure of NbSe_2; and (5)delta_S is more isotropic and
has a three-dimensional-like feature and is located either on the Se or the
bonding Nb Fermi sheets.Comment: 16 pages, 4 figure
Western North Pacific Typhoons with Concentric Eyewalls
Mon. Wea. Rev. 137, 3758-3770.This study examines the intensity change and moat dynamics of typhoons with concentric eyewalls using passive microwave data and best track data in the western North Pacific between 1997 and 2006. Of the 225 typhoons examined, we have indentified 55 typhoons and 62 cases with concentric eyewalls. The data indicate that approximately 50% of Category 4 and 75% of Category 5 typhoons possessed concentric eyewalls at some point during their life time. While major typhoons are most likely to form the concentric eyewalls, the formation of concentric structure may not be necessarily at the lifetime maximum intensity. Approximately one-third of concentric eyewall cases are formed at the time of maximum intensity A theoretical parameter called filamentation moat width is devised. The filamentation moat width can be computed from the best track typhoon intensity and the passive microwave satellite-estimated inner eyewall radius for each typhoon with concentric eyewalls. The filamentation moat width explains 40% of the variance of the satellite observed moat width in the group with concentric eyewall formation intensity greater than 130 kts. The moat is generally recognized to be heavily influenced by the subsidence forced by the two eyewalls. Our results suggest that the rapid filamentation dynamics may also be contributing to the organizational aspect of the moat in very intense typhoons. The intensity time series in both the concentric and non-concentric composites are studied. Intensity of the concentric typhoons tends to peak at the time of secondary eyewall formation; but the standard model of intensification followed by weakening is valid for only half of the cases. Approximately 74% of the cases intensify 24 h before secondary eyewall formation and approximately 72% of the cases weaken 24 h after formation. The concentric composites have a much slower
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