Search for CP violation in tau and D decays with a K0S in the final state
Maurizio Martinelli
备注：
9 pages, 3 figures, proceedings for The Ninth International Conference on Flavor Physics and CP Violation (FPCP 2011) Maale Hachamisha, Israel, May 23-27, 2011
I report the recent searches for CP violation in tau and D decays including a K0S in the final state. The analyses herein shown are based on data samples recorded by BaBar and Belle experiments. A brief introduction on CP violation is followed by the summary of the experimental techniques and the results obtained for tau and D decays, respectively. Finally, an outlook on future development is provided.
Searches for Lepton Flavor Violation in the Decays tau -> e gamma and tau -> mu gamma
利用BaBar探测器在Upperdance（4S）、Upperdance（3S）和Upperdance（2S）共振附近收集的（963 +- 7）× 10^6 τ衰变的整个数据集，对τ轻子到较轻质量轻子和光子的轻子味破坏衰变进行了研究。搜索没有发现信号的证据，我们将分支分数的上限设为BR（tau -> e gamma）< 3.3 x 10^-8和BR（tau -> mu gamma）< 4.4 x 10^-8，置信水平为90%。
Search for Lepton Flavor Violation in the Decay tau -> mu gamma
利用PEP-II储存环上的BABAR探测器，在质心能量接近10.58 GeV时产生的2.07 x 10^8 e+e- -> tau+ tau-事件，对τ-> μ-γ衰变中轻子味数的不守恒进行了研究。我们没有发现信号存在的证据，因此在90%的置信水平下将BR（tau -> mu gamma）的分支比设为< 6.8 x 10^-8。
本文给出了τ轻子衰变中CP不守恒的研究结果。在CLEO和BELLE数据中都没有观察到CP对称性破坏的证据。这些结果的解释是在一个模型的框架内与标量玻色子交换。耦合常数Λ的虚部的限制，参数化将导致CP破坏的图的相对贡献，在90% C. L下为-0.046 < \Im（Λ）< 0.022。和|\Im（Λ）|π < 1.7 at 90% C.L. in tau->π ^0 nu_τ和τ-> K π ^0 nu_τ模式。
Search for Lepton Flavour Violation in the Decay tau -> mu gamma
用PEP-Ⅱ储存环上的BABAR探测器在e+e-质心能量为10.58 GeV处收集的221.4/fb的数据，对轻子味破坏衰变τ-> μ-γ进行了搜索。对于6.2+/-0.5起事件的预期背景水平，检索的效率为（7.45+/-0.65）%。在最终样本中，选择4个候选事件。由于没有证据表明该数据中存在信号，因此对于该初步结果，我们使用Feldman和Brachins的方法，在90%CL下将BR（tau -> mu gamma）的上限设定为< 9 x 10^-8。
We report a feasibility study of $CP$ violation of $τ^{-}\rightarrow K_{S}π^{-} ν_τ$ decay at a Super Tau Charm Facility~(STCF).With an expected luminosity of 1~ab$^{-1}$ collected by STCF per year at a center-of-mass energy of 4.26 GeV, the statistical sensitivity for the $CP$ violation is determined to be of order $9.7\times10^{-4}$ by measuring the decay-rate difference between $τ^{+}\rightarrow K_{S}π^{+}\barν_τ$ and $τ^{-}\rightarrow K_{S}π^{-} ν_τ$. The analysis is performed using a reliable fast simulation software package, which can describe the detector responses properly and vary the…
在末态中包含τ轻子的过程的研究将在Tevatron Run II中发挥重要作用。这样的最终状态对于电弱研究和测量以及对标准模型之外的物理学的研究都是相关的。本文讨论了与实施新的触发器集相关的物理机遇和挑战，这些触发器能够选择在最终状态中包含tau候选的事件。我们举例说明，特别是，各种新的物理场景，如超对称性（SUSY），超对称性与R-宇称违反，双线性宇称违反或违反轻子味模型的物理能力。最后，我们提出了第一次运行II的结果，使用一些所描述的tau触发器。
Searches for lepton flavor violation in tau decays are unambiguous signatures of new physics. The branching ratios of tau leptons at the level of 10^-10 - 10^-9 can be probed with 50 ab^-1 of electron-positron annihilation data being collected by the Belle II experiment at the world's highest luminosity accelerator, the SuperKEKB, located at the High Energy Accelerator Research Organization, KEK, in Tsukuba, Japan. Searches with such expected sensitivity will either discover new physics or strongly constrain several new physics models.
Charged lepton flavor violation has long been recognized as unambiguous signature of New Physics. Here we describe the physics capabilities and discovery potential of New Physics models with charged lepton flavor violation in the tau sector as its experimental signature. Current experimental status from the B-Factory experiments BaBar, Belle and Belle II, and future prospects at Super Tau Charm Factory, LHC, EIC and FCC-ee experiments to discover New Physics via charged lepton flavor violation in the tau sector are discussed in detail. Submitted to the Proceedings of the US Community Study on …
Within the Standard Model Effective Field Theory framework, with operators up to dimension 6, we perform a model-independent analysis of the lepton-flavour-violating processes involving tau leptons. Namely, we study hadronic tau decays and $\ell$--$τ$ conversion in nuclei, with $\ell = e,μ$. Based on available experimental limits, we establish constraints on the Wilson coefficients of the operators contributing to these processes. Our work paves the way to extract the related information from Belle II and foreseen future experiments.
我们考虑了τ->K pi pi nu_tau中的CP破坏效应，假设带电的希格斯玻色子提供了一个新的振幅，可以干扰通常的标准模型振幅。我们考虑四个CP奇观测量--常规速率不对称性、两个修改的速率不对称性和三重积不对称性。规则的速率不对称性预计是小的，因为它需要新的物理振幅与包含强子标量形状因子的标准模型振幅的干涉。其他CP不对称性可能在其新的物理范围方面更有前途。数值估计表明，修改后的三重产品的不对称性的最大可获得的值是百分之一的顺序。
We study Lepton Flavour Violating hadron decays of the tau lepton within the Simplest Little Higgs model. Namely we consider $τ\rightarrow μ(P, V, PP)$ where $P$ and $V$ are short for a pseudoscalar and a vector meson. We find that, in the most positive scenarios, branching ratios for these processes are predicted to be, at least, four orders of magnitude smaller than present experimental bounds.
Within the Standard Model Effective Field Theory framework, with operators up to dimension 6, we perform a model-independent analysis of the lepton-flavour-violating processes involving tau leptons. Namely, we study hadronic tau decays and $\ell$-$τ$ conversion in nuclei ($\ell=e,μ$). Based on available experimental limits, we establish constraints on the Wilson coefficients of the operators contributing to these processes. The related information from Belle II and foreseen future experiments can be easily incorporated into the resulting framework.
我们考虑了τ-> 3 pi nu_ tau和4 pi nu_ tau（Δ S = 0）以及τ-> K pi pi nu_tau（Δ S = 1）中的CP破坏效应，假设这些过程的通常标准模型振幅干扰了带电希格斯玻色子介导的类似振幅。在Delta S = 0的情况下，我们特别关注中间共振过程tau -> V pi nu_tau（V=omega，rho和a_1），并考虑三个CP-奇数观测值-部分速率不对称性，偏振相关不对称性和三重产物不对称性。在Delta S = 1的情况下，我们研究部分利率不对称，两个“修改”利率不对称，和三重产品不对称。预计Delta S = 0和Delta S = 1情况下的部分速率不对称性较小。对其他不对称性的评估表明，它们可能是可以测量的。
We confront the indications of lepton flavor universality (LFU) violation observed in semi-tauonic $B$ meson decays with new physics (NP) searches using high $p_T$ tau leptons at the LHC. Using effective field theory arguments we correlate possible non-standard contributions to semi-tauonic charged currents with the $τ^+ τ^-$ signature at high energy hadron colliders. Several representative standard model extensions put forward to explain the anomaly are examined in detail: (i) weak triplet of color-neutral vector resonances, (ii) second Higgs doublet and (iii) scalar or (iv) vector leptoquark…
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}…
Search for charged Higgs bosons through the violation of lepton universality in ttbar events using pp collision data at sqrt(s) = 7 TeV with the ATLAS experiment
在标准模型的几个扩展中，除了标准模型的t衰变为bW之外，顶夸克还可以衰变为底夸克和轻荷希格斯玻色子H+，t衰变为bH+。由于W玻色子平均衰变为三代轻子，而H+主要衰变为τ +nu，因此可以利用顶夸克衰变中轻子普适性的破坏来寻找带电的希格斯玻色子玻色子。本文的分析是基于大型强子对撞机ATLAS实验收集的sqrt（s）= 7 TeV的4.6/fb质子-质子碰撞数据。使用包含轻子（e或mu）和/或强子衰变τ（tau_had）的签名。事件产率之间的e+tau_had和e+mu，以及mu+tau_had和mu+e，最终状态的数据进行测量，并从模拟的预测进行比较。这种基于比率的方法减少了分析中系统不确定性的影响。未观察到与标准模型预测的显著偏差。假设分支分数B（H+ to tau+nu）为100%，对于90-140 GeV范围内的带电希格斯玻色子质量m（H+），分支分数B（t to bH+）的上限可以设置在3.2%-4.4%的范围内。结合利用τ_had+喷流末态在ttbar衰变中寻找带电希格斯玻色子的结果，当m（H+）在90-160 GeV范围内时，B（t到bH+）的上限可以设定在0.8%-3.4%。
We investigate the bounds on tau-mu lepton flavor violation (LFV). Our main focus is on the collider constrains on tau-mu LFV. We use the Type-III Two-Higgs-Doublet-Model (2HDM) as a set up for our study. While the LFV branching fraction of the 125 GeV is well constrained by current LHC searches, the heavier neutral states could have a large branching fraction to tau and muon. We estimate the LHC reach for the 13 TeV center of mass energy with 300 $\text{fb}^{-1}$ luminosity for a neutral boson decaying into a tau and a muon. We identify parts of the LFV parameter space where the searches for …
The singly charged $SU(2)_L$ singlet scalar, with its necessarily flavour violating couplings to leptons, lends itself particularly well for an explanation of the Cabibbo Angle Anomaly and of hints for lepton flavour universality violation in $τ\to μ\bar νν$. In a setup addressing both anomalies, we predict loop-induced effects in $τ\to eγ$ and in $τ\to eμμ$. A recast of ATLAS selectron and smuon searches allows us to derive a coupling-independent lower limit of $\approx 200$ GeV on the mass of the singly charged singlet scalar. At a future $e^+e^-$ collider, dark matter mono-photon searches c…
Search for Charged Lepton Flavor Violation in Narrow Upsilon Decays
带电轻子味破坏过程在标准模型中是不可观测的，但在标准模型的几个扩展中，包括超对称性和包含轻子夸克或复合的模型中，它们被预测会得到增强。我们在用BABAR探测器收集的99 M Y（2S）和117 M Y（3S）衰变样品中寻找这样的过程。我们在10^（-6）水平上对分支分数BF（Y（nS）-> e τ）和BF（Y（nS）-> mu τ）（n = 2，3）设置上限，并利用这些结果对违反有效算符的带电轻子味的质量标度设置1 TeV量级的下限。
Institute of Physics, Academia Sinica（中央研究院物理研究所）；Hebei Normal University（河北师范大学）；Tsung-Dao Lee Institute and School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学李政道理论与研究学院及物理与天文学院）；University of Chinese Academy of Sciences（中国科学院大学）；Beijing Normal University（北京师范大学）；National Centre for Nuclear Research（国家核研究中心）；Uppsala University（乌普萨拉大学）；University of Science and Technology of China（中国科学技术大学）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；Henan Normal University（河南师范大学）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；High Energy Physics Center, Chung-Ang University（中央大学高能物理中心）；Particle and Nuclear Physics Institute, Institute for Basic Science（基础科学研究院粒子与核物理研究所）；Huazhong University of Science and Technology（华中科技大学）
