K—K共振态

最近实验指出,在π^-+p→K+K+n以及K^-+p→K+K+A反应中,存在K-K的共振态,共振能量为1.02BeV。不少人对K-K共振态进行了分析,但并没得出一致的结论。本文从场论观点出发,在链式近似下,研究了有关K-K共振的一些问题,计算结果表明,在1.02BeV附近可能存在两个共振态,而1.02BeV的K-K共振对应T=0,J^PG++态较为合理。     

Determination of Chemical Effect on the Kβ1/Kα, Kβ2/Kα, Kβ2/Kβ1 and Kβ/Kα X-Ray Intensity Ratios of 4d Transition Metals

It is clear that detailed studies performed under identical experimental conditions are desirable to determine the effect of the chemical environment on the value of intensity ratios. To better understand this effect, we conducted measurements on Kβ₁/Kα, Kβ₂/Kα, Kβ₂/Kβ₁ and Kβ/Kα x-ray intensity ratios. The Kα and Kβ_1,2 emission spectra for compounds of 4d transition metals Y, Zr, Nb, and Mo were measured using a Si(Li) solid-state detector. The samples were excited by 22.69 keV x-rays emitted from a ¹⁰⁹Cd radioisotopes source. The experimental results for pure elements are compared with the other experimental and theoretical values.     

Chiral anomaly in Kγ → Kπ reactions

Implications of the chiral anomaly for the cross sections of the reactions K ⁺γ → K ⁺π⁰, K ⁰γ → K ⁰π⁰, K ⁺γ → K ⁰π⁺, and K ⁰γ → K ⁺π^? are investigated. Near the threshold, the contribution of the chiral anomaly dominates the cross sections for the first and the second reaction. These cross sections are compared with the cross sections for the third and the fourth reaction, which receive no contribution from the chiral anomaly. Prospects for an experimental study of the KKπγ vertex in the Coulomb production of π mesons by a K-meson beam are discussed.     

Scalar mesons in ππ and K¯K scattering

The s-wave pion scattering amplitude is analysed with the aim to clarify the mass spectrum of scalar mesons and to find evidence of lightest glueball. The S-matrix and K¯K coupled channel formalism is used. The existence of scalar mesons S^* and is implied by the data. The production K¯K and the elastic K¯KK¯K coupled amplitudes are predicted from the scattering data. The couplings c f S^* to and K¯K states are determined.     

K+ momentum spectrum from (K−, K+) reactions in the intranuclear cascade model

In the framework of intranuclear cascade (INC) type calculations, we study the momentum spectrum in the reactions (K⁻, K⁺) at a beam momentum of 1.65 GeV/c. The INC model calculations are compared with the relativistic impulse approximation (RIA) calculations to perform a detailed study of the reaction mechanism. We find that the INC model can reproduce the experimental data on various targets. Especially, in the low-momentum region, the forward-angle cross sections of the (K⁻, K⁺) reaction from light to heavy targets are consistently explained with the two-step strangeness exchange and production processes with various intermediate mesons, and φ, a₀ and f₀ productions and their decay into K⁺K⁻. In the two-step processes, inclusion of meson and hyperon resonances is found to be essential.     

Analysis of the K S K S system from the reaction π − p → K S K S n at 40 GeV

On the basis of experimental data from the 6-m spectrometer of the Institute of Theoretical and Experimental Physics (ITEP, Moscow), an amplitude analysis of 40 553 events of the reaction π ^? p → K _S K _S n induced by a negatively charged pion of energy 40 GeV is performed over a broad momentumtransfer range by using a new procedure. The results for |t| > 0.1 GeV² are obtained for the first time. In particular, resonances of mass 1700 and 1900 MeV and width 120 MeV are discovered in the D ₊ wave (there were no such resonances for |t| < 0.1 GeV²). In the region of low momentum transfers, the S wave exhibits a structure that lies in the mass region around 1370 MeV and which requires three resonances for its explanation. Two of these (that of mass 1234 ± 6 MeV and width 47 ± 33 MeV and that of mass 1478 ± 6 MeV and width 119 ± 10 MeV) were found in the studies of A. Etkin et al. [Phys. Rev. D 25, 2446 (1982)] and O.N. Baloshin et al. {Yad. Fiz. 43, 1487 (1986) [Phys. At. Nucl. 43, 959 (1986)]}. The third has a mass of 1389 ± 9 MeV and a width of 30 ± 24 MeV. At high momentum transfers, the S wave is found to feature resonances that have the following parameters: M = 1328 ± 8 MeV and Γ = 237 ± 20 MeV, M = 1440 ± 6 MeV and Γ = 121 ± 15 MeV, and M = 1776 ± 15 MeV and Γ = 250 ± 30 MeV. For the D ₀ wave, it is found that, in addition to the well-known resonances f ₂, a ₂, and f′ ₂, there appear the following resonances in this wave: a resonance of mass 2005 ± 12 MeV and width 209 ± 32 MeV and a resonance of mass 2270 ± 12 MeV and width 90 ± 29 MeV at low |t| and a resonance of mass 1659 ± 6 and width 152 ± 18 and a resonance of mass 2200 ± 13 MeV and width 91 ± 62 MeV at high |t|.     

The K * Kπ and ρππ couplings in QCD

The light cone QCD sum rules are derived for the K ^* Kπ coupling g _K ^* Kπ and the ρππ coupling g _ρππ. The contribution from the excited states and the continuum is subtracted cleanly through the double Borel transform with respect to the two external momenta, p ₁ ², p ₂ ²= (p−q)². Our result g _K ^* Kπ= (8.7 ± 0.5) and g _ρππ= (11.5 ± 0.8) is in good agreement with the experimental value. Received: 31 July 1998 / Revised version: 20 November 1998     

高温合金K5,K18杂质光谱分析的研究

一、前言众所周知,光谱分析一般都必须有相应的光谱标样。然而解决光谱标样并非易事。我们在分析高温合金K5、K18中Si、Fe、Mn、P、S杂质元素时,在没有相应的光谱标样条件下,采用高温合金GH49,利用控制试样法很好地解决了上述五个杂质元素的分析。二、实验部分K5、K18及GH49均为镍基高温合金,其组成差别不大、杂质元素Si、Fe、Mn、P、S的含量都很低。能否用GH49标准分析K5、K18中的杂质,其关键就在于这些杂质元素的蒸发与激发特性。因此首先应该研究这些杂质元素光谱线的蒸发特性与激发特性。     

Flavor annihilation and the decaysD s →K 0 * K

We have studied \(D_s^ + \to K_0^{* + } \bar K^0\) and \(D_s^ + \to \bar K_0^{*0} K^ +\) decays in the factorization of the hadron currents approximation. The spectator model leads the decays have different but negligible branching ratios. We show, however, that the inclusion of annihilation contribution can enhance the branching ratios. We predict that \(B(D_s^ + \to \bar K_0^{*0} K^ + )\) and \(B(D_s^ + \to K_0^{* + } \bar K^0 )\) could be around 2%.     

昂尼斯氮气在110K～600K的热力学量

采用氮分子气体系统的第二维里系数B和第三维里系数C的实验数据,用最小二乘法对这两个维里系数随温度的变化规律进行了数值模拟,并给出了拟合后的解析结果;以昂尼斯方程和上述规律为基础,采用热力学方法,在二级近似下,得到了昂尼斯氮气的态函数内能、焓以及可观测的定压摩尔热容量,并将在110K~600K范围内的定压摩尔热容量的计算结果与可查找的实验数据进行了比较,相应的百分误差表明,昂尼斯方程导致的结果与实验数据符合得很好.     

K介子工厂KAON

加拿大正在考虑花费四亿五千万美元,在已有的π介子工厂TRIUMF的基础上扩建成新的粒子工厂——K介子工厂,并简称为KAON. K介子工厂顾名思义是制作大量K介子的“工厂”.计划之中的KAON由以下三部分构成: 1.加速器:产生能量高(30GeV)、束流强(6 × 1014个/s)的质子初级束流. 2.靶:将这些强流质子束,打在固定靶上产生出大量次级粒子.用如此强流高能质子来产生大量次级粒子的靶,需要特别设计和解决许多特殊的技术问题,如散热等. 3.粒子束流的净化、分配装置:从这些次级粒子中,应用磁偏转、屏蔽、吸收等手段,最后制作出“纯净”的、能量…     

关于Kπ共振态

一、引言 目前,实验上发现可能存在两个Kπ共振态:K(885)和k(730)。实验上已经确定K(885)的量子数为 T=1/2,J~p=1~-。理论上也都一致认为它是矢量介子。不少作者用 bootstrap 动力学方法计算了K共振。他们结果的共同点是:肯定K(885)是存在的,但由于近似较粗略,因而定量的结果不够理想。     

零温物态方程输入参数B0K、B'0K和ρ0K的确定

在对Gruneisen系数高温高压下演化特性不作任何假设的前提下,建立了一种不依赖于等温物态方程具体形式,通过Hugoniot实验数据直接确定0 K零压等温体积模量B0K及其对压力的一阶导数B'0K和初始密度ρ0K等0 K物态方程输入参数的方法.通过与实验和理论数据的分析和比较,表明用这一方法确定的B0K和B'0K不仅合理,而且具有很高的精度,特别是B'0K的精度,要优于目前传统超声实验的测量精度.此外,这一方法所确定的ρ0K不仅在Gruneisen物态方程的框架内与相应的室温零压特性参数相适配,而且与低温热膨胀实验数据所确定的近0 K初始密度ρ0E非常吻合.     

神奇的K介子

在基本粒子物理学史中,K介子扮演了独一无二的角色。它不仅具有奇特的性质,其衰变在揭示基本的自然规律方面也是任何其他粒子所不能替代的。     

K—■共振态

最近实验指出,在π~-+p→Κ+n以及K~-+p→K+A反应中,存在K-的共振态,共振能量为1.02BeV。不少人对K-K共振态进行了分析,但并没得出一致的结论。本文从场论观点出发,在链式近似下,研究了有关K-共振的一些问题,计算结果表明,在1.02BeV附近可能存在两个共振态,而1.02BeV的K-共振对应T=0,J~(PG)=0~(++)态较为合理。     

零温物态方程输入参数B0K、B′0K和ρ0K的确定

在对Grtineisen系数高温高压下演化特性不作任何假设的前提下，建立了一种不依赖于等温物态方程具体形式，通过Hugoniot实验数据直接确定0K零压等温体积模量B0K及其对压力的一阶导数B′0k。和初始密度ρ0K等0K物态方程输入参数的方法。通过与实验和理论数据的分析和比较，表明用这一方法确定的．B0K和B′0k不仅合理，而且具有很高的精度，特别是B′0k的精度，要优于目前传统超声实验的测量精度。此外，这一方法所确定的ρ0K不仅在Grtineisen物态方程的框架内与相应的室温零压特性参数相适配，而且与低温热膨胀实验数据所确定的近0K初始密度ρ0E非常吻合。     

On Certain Kähler Quotients of Quaternionic Kähler Manifolds

We prove that, given a certain isometric action of a two-dimensional Abelian group A on a quaternionic Kähler manifold M which preserves a submanifold N ? M, the quotient M′ = N/A has a natural Kähler structure. We verify that the assumptions on the group action and on the submanifold N ? M are satisfied for a large class of examples obtained from the supergravity c-map. In particular, we find that all quaternionic Kähler manifolds M in the image of the c-map admit an integrable complex structure compatible with the quaternionic structure, such that N ? M is a complex submanifold. Finally, we discuss how the existence of the Kähler structure on M′ is required by the consistency of spontaneous ${\mathcal{N} = 2}$ to ${\mathcal{N} = 1}$ supersymmetry breaking.     

2π→2K的散射和πK的弹性散射

本文利用场流关系和低能定理求得2π→2K低能散射的截面,并利用交叉对称性得到低能πK弹性散射截面和散射长度。     

A theoretical prediction for exclusive decaysB→K(K*)η c

The decay rates for the exclusiveB decaysBK _c andBK* _c are calculated in the context of the heavy quark effective theory. We obtain(BK _c )/ (BK)=1.6±0.2 and(BK* _c )/ (K*)=0.39±0.04. These results lead to estimates BR(BK _c )=(0.11±0.02)% and BR(BK* _c )=(0.05±0.01)% if we use the central current experimental values forB(K, K ^*) branching ratios.