共查询到20条相似文献,搜索用时 15 毫秒
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R. C. Verma A. N. Kamal M. P. Khanna 《Zeitschrift fur Physik C Particles and Fields》1995,65(2):255-262
We have carried out a study of Cabbibbo-favored two-body decays ofD 0 andD s + involving η and η′ in the final state, $D^0 \to (\eta ,\eta ')\bar K^0 , D^0 \to (\eta ,\eta ')\bar K*^0 $ andD s + →(η,η′)π +,D s + →(η,η′)ρ +. We have introduced an annihilation term wherever admissible, and investigated its size if it were to bridge the gap between theory and experiment in each case. We have also related the semileptonic rates forD s + →(η,η′)e + v to those of the hadronic rates forD s + →(η,η′)π + and unveiled a puzzle. We offer a possible solution. 相似文献
3.
New measurements of the reactione
+
e
– confirm previous evidence for the decay1 and provide a strong constraint on the mass of the1. The results from a detailed analysis of these data are compared with those from a corresponding analysis of new data on the reactione
+
e
–. It is shown that
in accord with expectation. This identification of a strong1 decay supports a previous claim that the1 and theC(1480), observed in the channel, cannot be different manifestations of the same particle. 相似文献
4.
《Solid State Communications》1999,112(5):245-249
We report on three different and complementary measurements, namely magnetization measurements, positron annihilation and NMR spectroscopy, which give evidence that the formation of oxygen vacancy clusters is the origin of the fishtail anomaly in YBa2Cu3O7−δ. In contrast to YBa2Cu3O7.0, where the anomaly is intrinsically absent, it can be suppressed in the optimally doped state where vacancies are present. Thus, clusters of oxygen vacancies rather than single vacancies or point defects are responsible for this anomaly. 相似文献
5.
《Nuclear Physics B》2001,609(3):469-498
6.
V. V. Barmin A. E. Asratyan V. S. Borisov C. Curceanu G. V. Davidenko A. G. Dolgolenko C. Guaraldo M. A. Kubantsev I. F. Larin V. A. Matveev V. A. Shebanov N. N. Shishov L. I. Sokolov G. K. Tumanov V. S. Verebryusov 《Physics of Atomic Nuclei》2010,73(7):1164-1167
The data on the reactions K +Xe → K 0 γX and K +Xe → K + γX, obtained with the bubble chamber DIANA, have been analyzed for possible radiative decays of the Θ+(1540) baryon: Θ+ → K 0 pγ and Θ+ → K + nγ. No signals have been observed, and we derive the upper limits Γ(Θ+ → K 0 pγ)/Γ(Θ+ → K 0 p) < 0.032 and Γ(Θ+ → K + nγ)/Γ(Θ+ → K + nγ) < 0.041 which, using our previous measurement of Γ(Θ+ → KN) = 0.39 ± 0.10 MeV, translate to Γ(Θ+ → K 0 pγ) < 8 keV and Γ(Θ+ → K + nγ) < 11 keV at 90% confidence level. We have also measured the cross sections of K +-induced reactions involving emission of a neutral pion: σ(K + n → K 0 pπ 0) = 68 ± 18 µb and σ(K + N → K + Nπ 0) = 30 ± 8 µb for incident K + momentum of 640 MeV. 相似文献
7.
By employing the perturbative QCD (pQCD) factorization approach, we calculate the full leading and the partial next-to-leading order (NLO) contributions to the seven B →πη(′) and η(′)η(′) decays. For B^+→ π+η(′) decays, the pQCD predictions for their decay rates agree very well with the data after the inclusion of the small NLO contributions. For neutral decays, the pQCD predictions are also consistent with the experimental upper limits and can be tested by the LHC experiments. The measured value of dir .Acp^dir(π+η)= 19±7% can also be accommodated by the pQCD approach. 相似文献
8.
We studied the dielectric properties of nano-sized liquid water samples confined in polymerized silicates MCM-41 characterized
by pore sizes 3–10 nm. Freezing temperature suppression in nanopores helps keep the water samples in liquid form at temperatures
well below 0°C and thus effectively study the properties of supercooled liquid water. We report the first direct measurements
of the dielectric constant by the dielectric spectroscopy method and demonstrate very clear signatures of the second-order
phase transition of ferroelectric nature at temperatures next to the λ-point in the supercooled bulk water in full agreement
with the recently developed model of the polar liquid. 相似文献
9.
《中国物理C(英文版)》2019,(8)
We study the hadronic decays of ∧_c~+ to the final states ∑~+η and ∑~+η',using an e~+e~-annihilation data sample of 567 pb~(-1) taken at a center-of-mass energy of 4.6 GeV with the BESIII detector at the BEPCⅡ collider.We find evidence for the decays ∧_c~+→∑~+η and ∑~+η' with statistical significance of 2.5σ and 3.2σ,respectively.Normalizing to the reference decays ∧_c~+→∑~+π0 and ∑~+ω,we obtain the ratios of the branching fractions■and ■to be 0.35±0.16±0.02 and 0.86±0.34±0.04,respectively.The upper limits at the 90% confidence level are set to be■and■.Using BESIII measurements of the branching fractions of the reference decays,we determine B(∧_c~+→∑~+η)=(0.41±0.19±0.05)%(0.68%)and B(∧_c~+→∑~+η')=(1.34±0.53 ±0.19)%(1.9%).Here,the first uncertainties are statistical and the second systematic.The obtained branching fraction of ∧_c~+→∑~+η is consistent with the previous measurement,and the branching fraction of ∧_c~+→∑~+η' is measured for the first time. 相似文献
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B. Borasoy 《The European Physical Journal A - Hadrons and Nuclei》2000,7(2):255-259
We compare two different frameworks which have been proposed to include the η′ in chiral perturbation theory. The equivalence
of these two approaches is shown both for the purely mesonic case and in the presence of the ground state baryon octet. The
relation between the different sets of parameters in both Lagrangians is clarified.
Received: 3 November 1999 / Revised version: 10 January 2000 相似文献
12.
We present a new formulation of one of the major radiative corrections to the weak charge of the proton-that arising from the axial-vector hadron part of the γZ box diagram, ?e□(γZ)(A). This formulation, based on dispersion relations, relates the γZ contributions to moments of the F(3)(γZ) interference structure function. It has a clear connection to the pioneering work of Marciano and Sirlin, and enables a systematic approach to improved numerical precision. Using currently available data, the total correction from all intermediate states is ?e□(γZ)(A)=0.004?4(4) at zero energy, which shifts the theoretical estimate of the proton weak charge from 0.071?3(8) to 0.070?5(8). The energy dependence of this result, which is vital for interpreting the Q(weak) experiment, is also determined. 相似文献
13.
D. Klabučar 《Physics of Particles and Nuclei》2008,39(7):1186-1186
14.
The light unflavoured meson η/η' decays are valuable for testing non-perturbative quantum chromodynamics and exploring new physics beyond the Standard Model. This paper describes a series of event generators, including η/η'→γl~+l~-, η/η'→γπ~+π~-, η'→ωe~+e~-, η→π~+π~-π~0, η/η'→π~0π~0π~0, η'→ηππ andη'→π~+π~-π~+π~-/π~+π~-π~0π~0, which have been developed for investigating η/ηdecay dynamics. For most of these generators, their usability has been validated in BESIII analyses for determining the detection efficiency, and background studies. The consistency between data and Monte Carlo shows that these generators work well in the BESⅢ simulation, and will also be useful for ongoing BESⅢ analyses and other experiments for studying η/η' physics. 相似文献
15.
Mercury vacancy in Hg1-xCdxTe is not a two-level (as it was supposed until now), but a three-level acceptor. A third, most shallow (1–1.5 meV) level (А+ state) appears due to a capture of a third hole by a neutral acceptor, after the two deeper vacancy levels (A? and А0 states) are already occupied by holes. Due to a capture of nonequilibrium holes by neutral mercury vacancies (under radiation) a positive space charge region arises near an irradiated surface. This causes the anomalies of photoelectromagnetic effect, observed in р-Hg1?xCdxTe at T < 10–12 K. 相似文献
16.
H. Albrecht H. Ehrlichmann T. Hamacher A. Krüger A. Nau A. Nippe S. Nowak M. Reidenbach M. Sch?fer H. Schr?der et al. 《Zeitschrift fur Physik C Particles and Fields》1992,55(1):25-31
The production ofD
*(2010)+ andJ/ mesons and prompt leptons has been investigated ine
+
e
– interactions at the (1S) resonance energy. The data were collected at the storage ring DORIS II at DESY with the ARGUS detector. We obtain upper limits of BRdir ( (1S)D
*(2010)±+X)<0.019>0.019>x
p
>0.2) and BRdir ((1S)J/+X)<>–3, both at the 90% confidence level. From the prompt lepton analysis, a model dependent limit of BRdir ((1S)Y
c
+X)<0.034>0.034>Y
c
denoting a charm-containing particle) is derived.Supported by the German Bundesministerium für Forschung und Technologie, under contract number 054DO51P 相似文献
17.
Using thermo-field edynamics method,we calculate the efective mass and Debye screening mass of the gluon at finite temperature and finite density.The critical temperature and density for the dissociation of J/ψ and ψ′are obtained. 相似文献
18.
W. Hofmann 《Zeitschrift fur Physik C Particles and Fields》1981,10(4):351-356
Inclusive Production of mesons and baryons in quark jets at \(\sqrt s = 9.5 \ldots 36GeV\) and in decays of the γ(9.46) meson has been studied using the Quark Recombination Model (QRM). The model predictions for quark jets agree with data. The QRM-simulation of three-gluon decays of the γ(9.46) shows an enhancement of the inclusive baryon rate, as was observed recently by the DASP II experiment. 相似文献
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Experimental and Theoretical Evidence for the Existence of Broad Forbidden Gaps in the Three—Component Composite 总被引:2,自引:0,他引:2 下载免费PDF全文
The influence of localized resonance on the properties of band-gaps of the two-dimensional periodic composite are analysed numerically and experimentally by comparing the two-component phononic crystal with the three-component one. The three-component composite which exhibits localized resonance in the elastically soft coating ring is composed of a square array of coated cylinders embedded in an epoxy resin. The coated cylinders consist of a steel inner core and a rubber coating, which has much smaller wave velocity and mass density than the matrixand tile inner material. Tile measured transmission power of tile three-component composite drops to the noise level in a broad ultrasonic frequency interval in contrast to the binary composite, which is in good agreement with the calculation using the finite element method. 相似文献