In kaon physics, several new precision measurements on flavour variables and CP violation have performed in the recent years. Presented are a new precise determination of the CKM parameter |V_us|, which combines the results of all experiments together with recent theoretical progress, and new measurements of the ratio R_K = Gamma(K+ -> e+ nu)/Gamma(K+ -> mu+ nu), which is sensitive to contributions of a possible charged Higgs in the SUSY framework. Also, final results of a precision search for direct CP violation in charged kaon decays are presented.
The quantum interference between the decays of entangled neutral kaons is studied in the process $ϕ\rightarrow K_S K_L \rightarrowπ^+π^-π^+π^-$, which exhibits the characteristic Einstein--Podolsky--Rosen correlations that prevent both kaons to decay into $π^+π^-$ at the same time. This constitutes a very powerful tool for testing at the utmost precision the quantum coherence of the entangled kaon pair state, and to search for tiny decoherence and CPT violation effects, which may be justified in a quantum gravity framework. The analysed data sample was collected with the KLOE detector at DA$Φ$…
The availability of high-intensity kaon beams at the J-PARC Hadron Experimental Facility and the CERN SPS North Area, together with the abundant forward production of kaons at the LHC, gives rise to unique possibilities for sensitive tests of the Standard Model in the quark flavor sector. Precise measurements of the branching ratios for the flavor-changing neutral current decays $K\toπν\barν$ can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. Building on the success of the current generation of fixed-target experiments, initiatives are taking shape in b…
Kaon Radiative Decay K+ -> mu+ nu gamma at CKM at the Fermilab Main Injector
K ~+ -> mu+ nu γ衰变的高统计数据可以精确地确定与K ~+结构相关的形状因子和K ~+极化率。这项研究是可能的，在拟议的FNAL CKM实验。CKM（Charged Kaons at the Main Injector）是一台带有两个RICH的飞行中衰变谱仪，设计用于在主注入器上运行高K介子通量。辐射衰变数据将采取补充的主要CKM的努力，研究罕见的K介子衰变（K到π nu nubar），CKM的主要设计。我们在这里总结了K -> μ nu γ的基本物理，实验状态，以及CKM光谱仪将如何适应这项研究。
INFN（意大利国家核物理研究所）；Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH)（霍里亚·胡鲁贝伊国家核物理与核工程研究所）；Tohoku University（东北大学）；University of Palermo（巴勒莫大学）；University of Zagreb（萨格勒布大学）；Technische Universität München（慕尼黑工业大学）；Jagiellonian University（雅盖隆大学）
A measurement of the form factors of charged kaon semileptonic decays is presented, based on $4.4 \times 10^6$ $K^\pm \to π^0 e^\pm ν_e$ ($K^\pm_{e3}$) and $2.3 \times 10^6$ $K^\pm \to π^0 μ^\pm ν_μ$ ($K^\pm_{\mu3}$) decays collected in 2004 by the NA48/2 experiment. The results are obtained with improved precision as compared to earlier measurements. The combination of measurements in the $K^\pm_{e3}$ and $K^\pm_{\mu3}$ modes is also presented.
中性K介子系统提供了一个独特的可能性，以执行CPT不变性的基本测试，以及量子力学的基本原理。综述了CPT破坏的最新和最重要的限制，包括可能的退相干机制或洛伦兹对称性破缺，这可能是由量子引力引起的。实验结果与量子力学和CPT对称性的预期没有偏差，而在某些情况下的精度达到了有趣的普朗克尺度区域。最后，对在升级后的法国弗拉斯卡蒂DAFNE e ~+对撞机上进行这类实验研究的前景作了简要的讨论。
The KLOE-2 detector records decays of quantum-entangled pairs of neutral kaons produced in decays of phi mesons provided by the DAFNE accelerator at the Laboratori Nazionali di Frascati, Italy. This system allows for a broad range of studies of fundamental discrete symmetries including tests which are only feasible with entangled neutral mesons. This work reports on the Lorentz non-invariance and CPT violation searches with the KSKL->pi+pi-pi+pi- process in the framework of the Standard Model Extension. Moreover, status and results of quantum coherence tests with the same process are discussed…
The KLOE-2 experiment at the INFN Laboratori Nazionali di Frascati (LNF) completed its data-taking at the $e^+ e^-$ DA$Φ$NE collider, which implements an innovative collision scheme based on a crab-waist configuration, and achieved the integrated luminosity of more than 5 fb$^-1$. KLOE-2 represents the continuation of KLOE with an upgraded detector and an extended physics program which includes, among the main topics, neutral kaon interferometry and test of discrete symmetries . Entangled neutral kaon pairs produced at DA$Φ$NE are a unique tool to test discrete symmetries and quantum coherence…
本文介绍了CERN的NA 48/2和NA 62实验对K介子衰变中轻子味和轻子数破坏的研究结果。利用NA 62合作组在2007年收集的完整数据集，对K --> e nu和K --> mu nu衰变率的螺旋度抑制比RK进行了精确测量。数据样本总计为145，958个重建的K --> e nu候选者，具有11.0%的背景污染。结果为RK =（2.488 +- 0.010）× 10^{-5}，与标准模型的预期一致。本文还给出了轻子数破坏K ~+- -> pi ~+ mu ~+- mu ~+-衰变率的一个改进的上限。
The availability of high intensity kaon beams at the CERN SPS North Area gives rise to unique possibilities for sensitive tests of the Standard Model in the quark flavor sector. Precise measurements of the branching ratios for the flavor-changing neutral current decays $K\toπν\barν$ can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. Building on the success of the NA62 experiment, plans are taking shape at CERN for a comprehensive program that will include experimental phases to measure the branching ratio for $K^+\toπ^+ν\barν$ to ~5% and to $K_L\toπ^0ν\…
Modern Determination of Pion and Kaon Fragmentation Functions from SIA and High-Precision COMPASS SIDIS Multiplicities
School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM)（粒子与加速器学院，基础科学研究院）；AGH University, Faculty of Physics and Applied Computer Science（AGH科技大学，物理与应用计算机科学系）；PRISMA ++ Cluster of Excellence, Institut für Physik, Johannes Gutenberg-Universität Mainz（PRISMA ++ 卓越集群，物理学研究所，约翰内斯·古腾堡美因茨大学）；Institut für Theoretische Physik, Universität Münster（理论物理研究所，明斯特大学）
It is well known that protons and neutrons are made from constituents, called quarks and gluons, which give substructure to these particles. The goal of this project is to make measurements of the spatial distributions and the momenta of the quarks that provide a three-dimensional map of quarks in the nuclear medium. This knowledge provides the basis of our understanding of nuclear matter in terms of the dynamics of their internal constituents. This abstract focuses on the study of the contribution of the sea quarks and in particular of the strange sea to the proton spin structure. This study …
In this paper, we present a preliminary study of $CP$ violation effect of $K^{0}-\bar{K}^{0}$ system in $J/ψ$ decay. The $CP$ violation parameters $η_{+-}$ and $η_{00}$ as well as their corresponding phase $ϕ_{+-}$ and $ϕ_{00}$ can be determined by the difference of the time-dependent decay rates between $K^{0}$ and $\bar{K}^{0}$ produced from $J/ψ\rightarrow K^{-}π^{+}K^{0} + c.c.$ processes. We investigate the precisions of the measurements of the CP violation effect at the Super Tau-Charm facility(STCF), a $e^{+}e^{-}$ collider with a peak luminosity of $0.5\times10^{35}\ \rm{cm}^{-2}\rm{s}…
Precision measurements of the branching ratios (BRs) for rare kaon decays can provide unique constraints on CKM unitarity and may reveal the existence of new physics. The BRs for two of these decays, $K^+\toπ^+ν\barν$ and $K_L\toπ^0ν\barν$, are strongly suppressed in the Standard Model, while their rates can be calculated with very small theoretical uncertainties.These decays are potentially sensitive to high mass scales, and several models of new physics predict large deviations from the Standard Model. Much progress has been made recently in the measurement of the $K\toπν\barν$ BRs. Followin…
