Semileptonic Decays of Bc Meson to a P—Wave Charmonium State χc or hc

The semileptonic decays of meson Bc to a P-wave charmonium state χc(3PJ) or hc(1P1)are computed.The results show that the decays are sizable so they are accessible in Tevatron and LHC,especially,with the detectors LHCB and BTeV in the foreseeable future,and of them,the one to the 1P1 charmonium state potentially offers us a novel window to see the unconfirmed hc particle.In addition,it is pointed out that since the two charmonium radiative decays χc (3P1,2)→J/ψ γ have sizable branching ratios,the cascade decays of the concerned decays and the charmonium radiative decays may affect the result of observing Bc meson through the semileptonic decays Bc→J/ψ l vl substantially.     

超声纵波在孔隙砂岩中的传播特性实验*

为了深入研究不同入射频率下超声波纵波在砂岩中的传播特性,以灰、红、褐砂岩为研究对象,开展了基于50 k Hz、100 kHz、200 kHz、500 kHz和1000 kHz入射频率的超声波纵波测试。提取纵波波速、幅值衰减系数、主频幅值、波形能量这些声学参数,结合入射频率和砂岩孔隙率进行传播特性的相关性分析。结果表明,在3种砂岩中,纵波波速随入射频率增大呈非线性增长趋势,砂岩种类不同,波速增长规律也不同;波形能量和主频幅值随入射频率呈指数关系降低;灰、红砂岩纵波波速随孔隙率越大,下降速率越大,褐砂岩在同级孔隙率下波速差异性明显。建立了基于3种砂岩的入射频率和幅值衰减系数的回归方程;基于200 kHz的入射频率,建立了砂岩孔隙率于波形能量的回归方程,实际测试中建议采用200 kHz作为入射频率,可较好兼顾检测的灵敏度和探测距离。研究成果为建立声学参数与砂岩抗压强度之间的内在联系提供了更多数据支撑,为实际物探测试中超声波入射频率的选择提供参考。     

Superconducting state of Sr2RuO4 under magnetic fields

The layered perovskite Sr₂RuO₄ exhibits unconventional superconductivity below 1.5 K. There are now several key experimental facts which indicate that its superconducting symmetry is spin-triplet, p-wave, but some important features of its gap structure still need to be determined. In order to address some of the outstanding issues, we have performed a study of its thermodynamic behavior in the field-temperature phase diagram. Specific heat measurements give evidence for multiple superconducting gaps. We will discuss implications of this in relation to the idea of “orbital-dependent superconductivity”. We will also present the results of a search for a second superconducting transition under the magnetic field applied precisely parallel to the quasi-two-dimensional plane.     

Reflection of P-waves in a prestressed dissipative layered crust

The paper deals with overall reflection and transmission response of seismic P-waves in a multilayered medium where the whole medium is assumed to be dissipative and under uniform compressive initial stress. The layers are assumed to be homogeneous, each having different material properties. Using Biot’s theory of incremental deformation, analytical solutions are obtained by matrix method. Numerical results for a stack of four layers — modelling earth’s upper layers, show a decreasing trend in both the Reflection CoefficientsR _D ^PP andR _D ^PS of the reflected P and S-waves.     

Strong decays of P-wave mixing heavy-light 1~+ states

Many P-wave mixing heavy-light 1~+ states have not yet been discovered by experiment, while others have been discovered but without width information, or with large uncertainties on the widths. In this paper, the strong decays of the P-wave mixing heavy-light 1~+ states D0, D~±, D~±s, B0, B~±and Bs are studied by the improved BetheSalpeter(B-S) method with two conditions of mixing angle θ: one is θ = 35.3?; the other is considering a correction to the mixing angle θ =35.3?~+θ_1. Valuable predictions for the strong decay widths are obtained: Γ(D′01)=232 MeV,Γ(D01)=21.5 MeV, Γ(D′_1~±.)=232 MeV, Γ(D_1~±)=215 MeV, Γ(D′_(s1)~±)=0.0101 MeV, Γ(D~±s1)=0.950 MeV, Γ(B′_1~±)=263 MeV, Γ(B~±1) = 16.8 MeV, Γ(B′s1) = 0.01987 MeV and Γ(B_(s1)) = 0.412 MeV. It is found that the decay widths of D~±s1 and Bs1 are very sensitive to the mixing angle. The results will provide theoretical assistance to future experiments.     

Possible heavy molecular states composed of a pair of excited charm-strange mesons

The P-wave charm-strange mesons D_s0(2317) and D_s1(2460) lie below the DK and D^* K threshold respectively. They are extremely narrow because their strong decays violate the isospin symmetry. We study the possible heavy molecular states composed of a pair of excited charm strange mesons. As a byproduct, we also present the numerical results for the bottonium-like analogue.     

粲夸克偶素P波态χ_（c0）宽度测量

利用北京谱仪在北京正负电子对撞机上采集的３５０万（２Ｓ）事例，通过（２Ｓ）→γπ－和γＫ＋Ｋ－反应道测量了Ｘｃ０的总宽度．由ＭｏｎｔｅＣａｒｌｏ模拟给出的质量分辨函数，利用拟合Ｘｃ２谱形得到的质量分辨作标定后，用于Ｘｃ０宽度的拟合，得到Ｘｃ０的宽度为（１５．０）ＭｅＶ．同时定出了ＸｃＪ（Ｊ＝０，２）到π＋π＝和Ｋ＋Ｋ－的衰变分支比．结果为Ｂ（Ｘｃ０→π＋π－）＝（４．２７±０．２３±Ｏ．６０）×１０－３；Ｂ（Ｘｃ０→Ｋ＋Ｋ－）＝（３．４４±０．２１±０．４７×１０－３；Ｂ（Ｘｃ２→π＋π－）＝（１．５２±０．１７±０．２９）×１０－３和Ｂ（Ｘｃ２→Ｋ＋Ｋ－）＝（５．２±１．１±１．８）×１０－４，其中第一项误差为统计误差，第二项为系统误差。     

A Study of One S- and One P-Wave Heavy Meson Interaction in a Chiral Quark Model

The analytical forms of the interaction potentials between one pseudo-scalar/vector and one scalar/tensor/axial-vector heavy mesons are deduced based on a chiral quark model. Our results explicitly show the attractive property between the two heavy mesons. Consequently, a series of possible molecular states are obtained. It is expected that our study might shed some light on the popular discussions of the newly observed XYZ states.     

Propagation of P- and S-waves in initially stressed gravitating half space

The present paper contributes in studying the phase velocities of P- and S-waves in a half space subjected to a compressive initial stress and gravity field. The density and acceleration due to gravity vary quadratically along the depth. The dispersion equation is derived in a closed form. It is shown that the phase velocities depend not only on the initial stress, gravity, and direction of propagation but also on the inhomogeneity parameter associated with the density and acceleration due to gravity. Various particular cases are obtained, and the results match with the classical results. Numerical investigations on the phase velocities of P- and S-waves against the wave number are made for various sets of values of the material parameters, and the results are illustrated graphically. The graphical user interface model is developed to generalize the effect.