Comments on |V ub /V cb | and |V ub | from non-leptonic B decays within the perturbative QCD approach

The Color String Percolation Model (CSPM) is used to determine the equation of state (EOS) of the Quark–Gluon Plasma (QGP) produced in central Au–Au collisions at $\sqrt{s_{\mathit{NN}}} = 200$  A GeV using STAR data at RHIC. When the initial density of interacting colored strings exceeds the 2D percolation threshold a cluster is formed, which defines the onset of color deconfinement. These interactions also produce fluctuations in the string tension which transforms the Schwinger particle (gluon) production mechanism into a maximum entropy thermal distribution analogous to QCD Hawking–Unruh radiation. The single string tension is determined by identifying the known value of the universal hadron limiting temperature T _c =167.7±2.6 MeV with the CSPM temperature at the critical percolation threshold parameter ξ _c =1.2. At midrapidity the initial Bjorken energy density and the initial temperature determine the number of degrees of freedom consistent with the formation of a ～2+1 flavor QGP. An analytic expression for the equation of state, the sound velocity $C_{s}^{2}(\xi)$ is obtained in CSPM. The CSPM $C_{s}^{2}(\xi)$ and the bulk thermodynamic values energy density ε/T ⁴ and entropy density s/T ³ are in excellent agreement in the phase transition region with recent lattice QCD simulations (LQCD) by the HotQCD Collaboration.     

Study of exclusive charmless semileptonic B decays and |Vub|

We study semileptonic B decay to the exclusive charmless states pi, rho/omega, eta, and eta;{'} using the 16 fb(-1) CLEO Upsilon(4S) data sample. We find B(B0-->pi-l+nu)=(1.37+/-0.15stat+/-0.11sys)x10(-4) and B(B0-->rho-l+nu)=(2.93+/-0.37stat+/-0.37sys)x10(-4) and find evidence for B+-->eta'l+nu, with B(B+-->eta'l+nu)=(2.66+/-0.80stat+/-0.56sys)x10(-4). From our B-->pilnu rate for q2>16 GeV2 and lattice QCD, we find |Vub|=(3.6+/0.4stat+/0.2syst-0.4thy+0.6)x10(-3) [corrected]     

Hard diffractive photon-proton scattering at large |t|

We propose to test perturbative QCD(pQCD) in the Regge limit by means of diffractive photon scattering, , at large and very high energies, . The helicity amplitudes of this process were calculated using the Lipatov solution of the BFKL equation for . We found that the perturbatively calculated cross section for this process is comparable in magnitude to the cross section for photoproduction assuming similar kinematics. Received: 9 September 1998 / Revised version: 2 October 1998 / Published online: 14 January 1999     

|m| Partial wave treatment for two-dimensional Coulomb-scattering and Regge pole

1 Introduction Though one-dimensional (1D) systems may clearly exhibit many features of quan-tum mechanics, systems with many degrees of freedom provide more opportunities tostudy many other important features, e.g. the degeneracy of energy eigenstates, whichneed a complete set of commuting observables to characterize an energy eigenstate. Inparticular, two-dimensional (2D) systems with two spatial degrees of freedom may ex-hibit symmetries not present in 1D systems, e.g. the rotational symme…     

Precision model independent determination of |Vub| from B --> pilnu

A precision method for determining |V(ub)| using the full range in q(2) of B --> pilnu data is presented. At large q(2) the form factor is taken from unquenched lattice QCD, at q(2) = 0 we impose a model independent constraint obtained from B --> pipi using the soft-collinear effective theory, and the shape is constrained using QCD dispersion relations. We find |V(ub)| = (3.54 +/- 0.170 +/- 0.44) x 10(-3). With 5% experimental error and 12% theory error, this is competitive with inclusive methods. Theory error is dominated by the input points, with negligible uncertainty from the dispersion relations.     

Regge cuts and large-|t| pp scattering

It is shown that recent measurements of the large-|t| pp elastic-scattering differential cross section at FNAL and CERN-ISR agree with earlier predictions based on the dominance of a pomeron pole(P) with αp(t) = 1.067 + 0.10 t, and a P ? P cut, out to the largest measured |t| values (12 GeV²). Some of the problems raised by this success are discussed.     

A determination of the Cabibbo-Kobayashi-Maskawa parameter |V us| using KL decays

We present a determination of the Cabibbo-Kobayashi-Maskawa parameter |V(us)| based on new measurements of the six largest K(L) branching fractions and semileptonic form factors by the KTeV (E832) experiment at Fermilab. We find |V(us)|=0.2252+/-0.0008(KTeV)+/-0.0021(ext), where the errors are from KTeV measurements and from external sources. We also use the measured branching fractions to determine the CP violation parameter |eta(+-)|=(2.228+/-0.005(KTeV)+/-0.009(ext))x10(-3).     

SU(l|m|n)阶化代数及其规范模型

本文将阶化李代数SU(m|n)扩充到SU(l|m|n),并讨论了它的局部规范理论。找到了规范不变的拉格郎日量,并将SU(2|1)弱电模型推广到统一强、弱、电相互作用模型。 关键词：     

Proposal for a precision measurement of |Vub|

A new method for a precision measurement of the Cabibbo-Kobayashi-Maskawa matrix element |V(ub)| is discussed, which combines good theoretical control with high efficiency and a powerful discrimination against charm background. The resulting combined theoretical uncertainty on |V(ub)| is estimated to be 10%.     

PEO|Sncl2|PANI composites: as an electrolyte in solid-state battery

Solid-state polymer electrolytes possess high conductivity and have advantages compared with their liquid counterparts. The polyethylene oxide (PEO)-based polymer is a good candidate for this purpose. The PEO/SnCl₂/polyaniline composite (PSP composites) at different weight percentages were prepared in anhydrous acetonitrile media. Structural studies were carried out of the prepared composites by X-ray diffraction, Fourier transmission infrared spectroscopy, and surface morphology by scanning electron microscopy. The σ _dc was carried out by a two-probe method, and it is found that the conductivity increases with an increase in temperature. The temperature-dependent conductivity of the composites exhibits a typical semi-conducting behavior and hence can be explained by the 1D variable range hopping model proposed by Mott. The electrochemical cell parameters for battery applications at room temperature have also been determined. The samples are fabricated for battery application in the configuration of Na: (PSP): (I₂?+?C?+?sample), and their experimental data are measured using Wagner’s polarization technique. The cell parameters result in an open-circuit voltage of 0.83 V and a short-circuit current of 912 μA for PSP (70:30:10) composite. Hence, these composites can be used in polymer electrolyte studies.     

水中激光击穿空泡的高速摄影研究

为了分析激光击穿液体介质过程中的等离子腔体、空泡脉动、近/远场声波特性等综合效应,将高速摄影技术应用于水下激光击穿研究.观察到了激光击穿形成的等离子体闪光、空泡脉动及溃灭过程,通过对所得照片的分析,得到了激光空泡生长的规律,实验结果与已有的水下空泡理论计算及采用光散射、压力传感器测量结果吻合较好,证明了高速摄影技术在水下激光击穿产生空泡特性研究中的重要作用.     

Synthesis,Structure and Magnetic Properties of Multilayer Nanoheterostructures Fe|MgO|Cr|MgO|Fe

Physics of the Solid State - Layered nanoheterostructure Fe|MgO|Cr|MgO|Fe is an artificial ferromagnetic material in which exchange interaction of magnetic moments in the iron layers through...     

利用x|x|控制混沌系统

提出了一种新的混沌控制方法，即对混沌动力系统增加一个具有分段二次函数x|x|形式的非线性反馈控制器，利用它控制了一大类系统从混沌运动转化为各种规则的运动.该控制器是一种活动控制器，它不影响原系统的参数，其结构相当简单而且在物理、电路上都容易实现.数值仿真表明了该控制方法的有效性与可行性. 关键词： 混沌 非线性反馈控制器 分段二次函数     

Measurement of the inclusive charmless semileptonic branching ratio of B mesons and determination of |V ub|

We report a measurement of the inclusive charmless semileptonic branching fraction of B mesons in a sample of 89 x 10(6) (-)BB events recorded with the BABAR detector at the Upsilon(4S) resonance. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson. The number of signal events is extracted from the mass distribution of the hadronic system accompanying the lepton and is used to determine the ratio of branching fractions B((-)B-->X(u)lnu;)/B((-)B-->Xlnu;)=[2.06+/-0.25(stat)+/-0.23(syst)+/-0.36(theo)]x10(-2). Using the measured branching fraction for inclusive semileptonic B decays, we find B((-)B-->X(u)lnu;)=[2.24+/-0.27(stat)+/-0.26(syst)+/-0.39(theo)]x10(-3) and derive the Cabibbo-Kobayashi-Maskawa matrix element |V(ub)|=[4.62+/-0.28(stat)+/-0.27(syst)+/-0.48(theo)]x10(-3).     

Molecular rectification of thiol-linked Au|PTCDI-[CH2]n|Au junctions

The electronic transport properties of the PTCDI-[CH₂]_n(0≤n≤6) molecular junctions with different molecular lengths are theoretically investigated via the first-principles density functional theory (DFT) and non-equilibrium Green's function (NEGF) method. Our results show that the transport properties depend on molecular lengths. The equilibrium conductance of the probed systems decreases exponentially with the increasing number n of the CH₂ unit. With n≥1, the rectifying effect has been found. In the n=6 case, a significant rectification ratio of 72.6 is achieved at the bias of ±2.1 V in our probed voltage range. The rectification effect arises from asymmetric molecular structures. Our results suggest these molecules have great potential application in the molecular-scale device.     

Evidence for production of single top quarks and first direct measurement of |Vtb|

The D0 Collaboration presents first evidence for the production of single top quarks at the Fermilab Tevatron pp[over ] collider. Using a 0.9 fb(-1) dataset, we apply a multivariate analysis to separate signal from background and measure sigma(pp[over ]-->tb+X,tqb+X)=4.9+/-1.4 pb. The probability to measure a cross section at this value or higher in the absence of a signal is 0.035%, corresponding to a 3.4 standard deviation significance. We use the cross section measurement to directly determine the Cabibbo-Kobayashi-Maskawa matrix element that describes the Wtb coupling and find 0.68<|V(tb)|相似文献   

| m | Partial wave treatment for two-dimensional Coulomb-scattering and Regge pole

The symmetry and |m| partial-wave analysis for two-dimensional (2D) Coulomb-scattering is investigated. As a function of energyE, the |m| partial-wave scattering amplitudef _|m|(θ) is analytically continuated to the, negativeE (complexk) plane, and it is found that the bound state energy eigenvalues (E<0) are just located at the poles off _|m|(θ) on the positive imaginaryk axis as is expected. In addition, as a function of |m|,f _|m|(θ) is analytically continuated to the complex |m| plane, the bound state energy eigenvalues are just located at the poles off _|m|(θ) on the positive real |m| axis.     

Determination of |Vub| from measurements of the electron and neutrino momenta in inclusive semileptonic B decays

We present a determination of the Cabibbo-Kobayashi-Maskawa matrix element |Vub| based on the analysis of semileptonic B decays from a sample of 88 x 10(6) Gamma(4S) decays collected with the BABAR detector at the SLAC PEP-II e+e- storage ring. Charmless semileptonic B decays are selected using measurements of the electron energy and the invariant mass squared of the electron-neutrino pair. We obtain |Vub| =(3.95 +/- 0.26(+0.58)(-0.42) +/- 0.25) x 10(-3), where the errors represent experimental uncertainties, heavy quark parameter uncertainties, and theoretical uncertainties, respectively.     

A new type of electrochemical cell based on the configuration NaI |PEG| I2

Different operating conditions of a new electrochemical cell based on sodium iodide and polyethylene glycol (PEG) polymer as separator as well as conducting electrolyte is reported. Five types of cells were fabricated using pure NaI, PC+NaI, water+NaI dil. HCl+NaI and dil. H₂SO₄+NaI in the cell configuration NaI |PEG| I₂ and NaI |PEG|s I₂+C. Their discharge characteristics were studied at room temperature (33 °C). From the cell parameters, it is found that the open circuit voltage ranges from 648 mV to 1023 mV and the short circuit current ranges from 29 μA to 4.8 mA.     

Study of deuterium and hydrogen distributions in Ta|CD<Subscript>2</Subscript>|Ta,Ta|Ta|CD<Subscript>2</Subscript>|Ta|Ta,and Nb|CD<Subscript>2</Subscript>|Nb assemblies after exposure to high-temperature argon plasma

Assemblies made of Ta|CD₂|Ta, Ta|Ta|CD₂|Ta|Ta and Nb|CD₂|Nb foils are irradiated with pulses of high-temperature argon plasma created by means of a “Plasma Focus” setup. The irradiated foil samples are investigated by recording the recoil nuclei of hydrogen and deuterium. It is found that hydrogen and deuterium are redistributed in foil stacks. The ultradeep penetration of light gas impurities (hydrogen and deuterium) can be explained by the influence of shock waves on the foils and accelerated diffusion under an external force.