Mateusz Lewczuk
The BaBar collaboration has accumulated over 400 million tau-pairs which can be used to study charged leptonic and hadronic weak currents to unprecedented precision. This note presents results on lepton universality, measurements of |V_us|, and searches for tau decays which violate lepton flavour conservation, or tau decays that proceed through a suppressed second class current.
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继续探索
We present a study for the measurement of of radiative decays, tau -> l gamma nu nu, l=e, mu, and tau -> pi gamma nu using 500 fb-1 of electron-positron annihilations recorded by the BaBar detector at the PEP-II asymmetric B-factory.
Lepton Flavor Violation in tau decays at BaBar
给出了BaBar实验中轻子味破坏τ-> l γ，τ-> lll和τ-> lhh衰变的实验结果.分支比的上限在10^{-7}的水平下获得，置信水平为90%。
Selected results from tau analyses performed using the BaBar detector at the SLAC National Accelerator Laboratory are presented. A precise measurement of the tau mass and the tau{+} tau{-} mass difference is undertaken using the hadronic decay mode tau- --> pi+ pi- pi- nu. In addition an investigation into the strange decay modes tau- --> K0S pi- pi0 nu and tau- --> K0S pi- nu is also presented, including a fit to the tau- --> K0S pi-nu invariant mass spectrum. Precise values for the Mass and Width of the K*(892) are obtained.
Charm and Tau Decays: Review of BaBar and Belle Results
本文评述了最近在Belle和BaBar实验中有关粲介子、粲重子和$τ$轻子衰变的结果。该综述于2008年3月8日至15日在LaThuile举行的第43届$^{rd}$ Rencontres de Moriond（QCD和高能相互作用）会议上发表。
A Search for the rare decay B0 --> tau+tau- at BABAR
我们给出了使用BABAR探测器在（232 +- 3）× 10^6 Upplane（4S）--> BBbar衰变的数据样本中搜索衰变B 0--> tau+tau-的结果。标准模型的某些扩展预测了这种罕见衰变的可测量水平。我们完全重建了一个中性B介子，并在事件的其余部分寻找信号衰减的证据。我们没有发现信号事件的证据，并在90%的置信水平下得到B（B 0--> tau+tau-）< 4.1 x 10^-3。
We present the most recent searches for lepton-flavor-violating tau decays in BaBar. We find no evidence of tau decaying to three charged leptons or to a charged lepton and a neutral meson (KS, rho, phi, K*0, anti-K*0), and set upper limits on the corresponding branching fractions between 1.8 and 19 times 10-8 at 90% confidence level.
We perform a measurement of the tau -> l gamma nu anti-nu (l = e, mu) branching fractions for a minimum photon energy of 10 MeV in the tau rest frame, using 431fb^-1 of e^+e^- collisions collected at the center-of-mass energy of the Upsilon(4S) resonance with the BaBar detector at the PEP-II storage rings. We find B(tau -> mu gamma nu anti-nu ) = (3.69pm0.03pm0.10)x10^-3, and B(tau -> e gamma nu anti-nu ) = (1.847pm0.015pm0.052)x10^-2, where the first quoted error is statistical, and the second is systematic. These results are substantially more precise than previous measurements.
Using data collected with the BaBar detector at PEP-II at SLAC, we report on several tau lepton measurements that are used to determine the modulus of the Cabibbo-Kobayashi-Maskawa matrix element Vus, and to check the Standard Model predictions of lepton universality and CPT conservation.
We perform a measurement of the branching fractions for tau -> l gamma nu anti-nu (l= e, mu) decays for a minimum photon energy of 10 MeV in the tau rest frame using 430 fb^-1 of e^+ e^- collisions collected at the center-of-mass energy of the Upsilon(4S) resonance around 10.58GeV with the BaBar detector at the PEP-II storage rings. We find B(tau -> mu gamma nu nu) = (3.69pm0.03pm0.10)x10^-3 and B(tau -> e gamma nu anti-nu) = (1.847pm0.015pm0.052)x10^-2 where the first quoted error is statistical and the second is systematic. These results represent a substantial improvement with respect to ex…
Measurement of the branching fraction B(tau- --> K0 pi- nu) using the BaBar detector
分支分数B（τ-> K 0 pi- nu）的初步测量是使用PEP-II对撞机提供的384.6 fb-1的e+e碰撞数据进行的，主要工作在sqrt（s）=10.58 GeV，并使用BaBar探测器记录。由此我们测量：B（tau-> K 0 pi- nu）=（0.840 +/- 0.004（stat）+/- 0.023（syst））%。这是迄今为止最精确的测量结果，与世界平均水平一致。
We report some new results on tau decays obtained by the BaBar collaboration using 468 inverse femtobarn of electron-positron collisions recorded at the PEP-II asymmetric collider at Stanford Linear Accelerator Center. First We will show the results for the branching fractions for the decay of the tau to a charged hadron and two neutral kaons and the branching fractions for high-multiplicity decays with 3 or 5 charged particles in the final state, either pions or kaons. We will then show the results for the search of second class hadronic current decays involving eta-prime mesons and the invar…
We report on analyses of tau lepton decays $τ^- \to ηK^- ν_τ$ and $τ^- \to ηπ^- ν_τ$, with $η\to π^+ π^- π^0$, using 470 fb$^{-1}$ of data from the Babar experiment at PEP-II, collected at center-of-mass energies at and near the $Υ(4S)$ resonance. We measure the branching fraction for the $τ^- \to ηK^- ν_τ$ decay mode, $\Br(τ^- \to ηK^- ν_τ) = (1.42\pm0.11\text{(stat)}\pm0.07\text{(syst)})\times10^{-4}$, and report a 95% confidence level upper limit for the second-class current process $τ^- \to ηπ^- ν_τ$, $\Br(τ^- \to ηπ^- ν_τ) < 9.9\times10^{-5}$.
A search for the decay of the positive B meson into a positive tau lepton and a tau neutrino at the BaBar experiment
我们提出了一个搜索的衰变B+ -> tau+ nu使用288个反femtobarns的数据收集在Upperion（4S）共振与BaBar探测器在SLAC PEP-II B工厂。选择具有一个重建的半轻子B衰变（B-> D_0 1- nu X）的事件的样本，并且在反冲中执行对信号衰变模式的搜索。在四个通道中识别tau。我们测量了BF（B+ -> tau+ nu）=（0.88+0.68 - 0.67（stat.）+- 0.11（系统））x 10^{-4}，并在90%置信水平下提取出1.8 x 10^{-4}的支化分数上限。
Recent results on two-photon and tau physics at BABAR
本文介绍了在SLAC的PEP-Ⅱ B工厂用BABAR探测器测量eta_c介子的总宽度γ_tot和质量M。基于88 fb ^-1数据样本的结果为Gamma_tot =（33.3 +-2.5（stat.）+-0.8（系统））M =（2983.3 ± 1.2 ± 1.8）MeV。在3.63 GeV附近观察到的增强可以解释为eta_c（2S）态的证据。此外，还描述了使用30.2 fb ^-1对τ轻子寿命的初步测量。测得的tau寿命为：（290.8 ± 1.5（stat.）+-1.6（系统））FS.
We present measurements of the branching fractions of 3-prong and 5-prong tau decay modes using a sample of 430 million tau lepton pairs, corresponding to an integrated luminosity of 468 fb-1, collected with the BaBar detector at the PEP-II asymmetric energy e+e- storage rings. The τ- --> (3π)- ην, τ- --> (3π)- ων, and τ- --> π- f_1(1285)ν, branching fractions are presented as well as a new limit on the branching fraction of the isospin-forbidden, second-class current, τ- --> π-η'(958)ν, decay. We find no evidence for charged kaons in these decay modes and place the first upper limits on their…
Measurement of |V_us| using hadronic tau decays from BaBar & Belle
我们测量了几个强子τ衰变到含有K介子的末态的分支分数，它可以用来确定奇异夸克质量和Cabibbo-Kobayashi-Maskawa夸克混合矩阵的元素|V_us|。这些结果是从分别在SLAC和KEK的PEP-II和KEKB非对称能量e+e对撞机上的BaBar和Belle探测器收集的数据中获得的，两者都在Y（4S）共振附近的质心能量下工作。
Results on Tau Physics from BaBar
最近的结果Tau物理从BaBar的评论。τ衰变过程τ->lll中轻子味破坏的极限是基于91.6 fb^1的数据给出的。在考虑的所有六种衰变模式中，数据中发现的事件数量与背景预期兼容，并且分支分数的上限设定在90%CL下的（1-3）10^-7范围内。根据110.7 fb^-1的数据，对五叉分支分数进行了初步测量，结果为B（tau- -> 3 h-2 h + nu）=（8.52+/-0.09+/-0.40）10^-4。在30 fb^-1的数据基础上，对τ寿命进行了初步测量，测得的τ寿命为290.8+/-1.5+/-1.6 fs。
We present the recent BaBar searches for the leptonic decay B+ --> tau+ nu and for the rare decay B --> K(*) nu nubar, using a data sample of about 470 x 10^6 BB pairs. Both searches use a technique in which one B meson is hadronically reconstructed before searching for evidence of the signal decay in the rest of the event. BaBar measures B(B+ --> tau+ nu) = (1.83 ^{+0.53}_{-0.49} +/- 0.24) x 10^{-4}, and preliminary upper limits at 90% confidence level of B(B --> K nu nubar) < 3.2 x 10^{-5} and B(B --> K* nu nubar) < 7.9 x 10^{-5}. We also discuss the expected observations and precision impro…
The BaBar experiment recorded 471 x 10^6 BBbar pairs at the Y(4S) resonance (corresponding to an integrated luminosity of 429 fb^-1). We present here a selection of recent results from the BaBar collaboration: search for lepton-number violation in the decay B^+ -> h^- l^+ l^+, search for lepton-flavor violation in B^+/- -> h^+/- tau l and CP-violation in tau^- -> pi^- KS (>= 0 pi^0) nu_tau.
We search for a light Higgs boson, $A^0$, in the radiative decay $Υ(3S)\toγA^0$, $A^0\toτ^+τ^-$, $τ^+\to e^+ν_e \barν_τ$ or $τ^+\to μ^+ ν_μ \barν_τ$. The data sample contains 122 million $Υ(3S)$ events recorded with the \babar detector. We find no evidence for a narrow structure in the studied $τ^+τ^-$ invariant mass region of $4.03<m_{τ^+τ^-}<10.10$ \gevcc. We exclude at the 90% confidence level (C.L.) a low mass Higgs decaying to $τ^+τ^-$ with a product branching fraction ${\cal {B}}(Υ(3S)\toγA^0)\times {\cal {B}}(A^0\toτ^+τ^-)$ $>(1.5-16)\times 10^{-5}$ across the $m_{τ^+τ^-}$ range. We als…
Using a sample of 122 million Upsilon(3S) decays collected with the BaBar detector at the PEP-II asymmetric energy collider at the SLAC National Accelerator Laboratory, we measure the ratio R_taumu=BR(Upsilon(1S)->tau^+tau^-)/BR(Upsilon(1S)->mu^+mu^-); the measurement is intended as a test of lepton universality and as a possible search for a light pseudoscalar Higgs boson in Next to Minimal Supersymmetric Standard Model (NMSSM) scenarios. Such a boson could appear in a deviation of the ratio R_taumu from the Standard Model expectation, that is 1, except for small lepton mass corrections. The …
We present some recent measurements of rare flavor-changing neutral current B decays, using data collected with the BABAR detector at the PEP-II e+e- collider at SLAC. First, we search for the rare process B+ -> K+ tau- tau+ and we do not find evidence for signal. The measured branching fraction is (1.31+0.66-0.61(stat.)+0.35-0.25(sys.)) x 10-3 with an upper limit, at the 90% confidence level, of B(B+ -> K+ tau+ tau-) < 2.25 x 10-3. We then study the lepton forward-backward asymmetry AFB and the longitudinal K* polarization FL in the rare decays B -> K* l+ l-, where l+ l- is either e+ e- or mu…
We present some recent measurements performed using 514 fb-1 of $e^+e^-$ collisions collected with the BaBar detector at the PEP-II asymmetric collider at SLAC. First we present a study of the decay tau -> K K_S nu, we measure the branching fraction B(tau -> K K_S nu), the mass spectrum of the K K_S system and obtain the spectral function. Our results are in agreement with and improve previous measurements. We then report a search for a dark boson A' produced in the reaction e+e- -> gamma A' in invisible final states A' -> chi anti-chi . We find no evidence for such processes and set 90% confi…
This article presents a model independent search for an additional, mostly sterile, Heavy Neutral Lepton (HNL), that is capable of mixing with the Standard Model $τ$ neutrino with a mixing strength of $|U_{τ4}|^{2}$, corresponding to the absolute square of the extended Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix element. Data from the \babar~ experiment, with a total integrated luminosity of $424~ \text{fb}^{-1}$, are analyzed using a kinematic approach that makes no assumptions on the model behind the origins of the HNL, its lifetime or decay modes. No significant signal is found. Upper lim…
Recent Searches for Exotic Physics at the BaBar/PEP-II B-factory
我提出了三个最近的结果，从搜索奇异的物理在BaBar/PEP-II B工厂。这些结果涵盖了B工厂生产的许多样品，包括B介子，τ轻子和Uppersons（3S）介子。我们已经搜索了CPT违反B混合，没有发现显着偏离无违反假设。我们还利用τ- -> ω l-和τ- -> l+ l- l+及其电荷共轭寻找τ的轻子味破坏衰变。我们没有发现这些过程的证据，并设置其分支分数的上限。最后，我们已经在衰变Uppermont（3S）-> gamma A0中寻找了低质量的希格斯玻色子，希格斯玻色子在那里衰变是不可见的。我们没有发现这种衰变的证据，并在可能的希格斯质量范围内设定了上限。
New Physics Searches at BaBar
我们将介绍BABAR合作组织关于罕见的B和轻子味违背（LFV）衰变的新物理搜索的最新结果，包括b -> s跃迁，纯轻子B衰变和LFV τ衰变。
Searching for New Physics: Results from Belle and Babar
$B$ -工厂提供了丰富的机会来寻找新的现象，在$B$，魅力和τ衰变。这里展示的是Belle和Babar最近的一些成绩。
A Search for the Decay B+ --> tau+ nu_tau
我们在SLAC PEP-II B工厂的BABAR探测器收集的232 × 10^6个BBbar对样品中寻找罕见的轻子衰变B+ --> tau+ nu_tau。信号事例是通过考察B介子反冲半轻子衰变B-> D*0 l-nu_lbar的性质来选择的.我们没有发现信号的证据，并在90%置信水平下将BR（B+ --> tau+ nu_tau）的分支分数上限设定为< 2.8x10^{-4}。我们将此结果与先前的统计独立的BABAR搜索B+ --> tau+ nu_tau相结合，以在90%置信水平下给出BR（B+ --> tau+ nu_tau）< 2.6x10^{-4}的上限。
We present recent results from the BaBar collaboration in several areas of research. These include searches for new physics via measurements of radiative-penguin B decays, lepton-number and lepton-flavor violations in B decays, and CP violation in tau lepton decays.
Leptonic Decays at BABAR
我们目前的轻子B衰变的数据收集的BaBar探测器在PEP-II非对称能量e+e-对撞机在斯坦福大学直线加速器中心。我们报告搜索的B -> tau nu衰变，基于两个统计独立的数据样本。
Preliminary BABAR results on B0 mixing with dileptons and on lifetime with partially reconstructed B0 decays
在PEP-II非对称B工厂的BABAR共振收集到的积分亮度为7.7 fb-1，我们测量到中性B本征态之间的质量差Δ（m_d）为（0.507+/-0.015+/-0.022）x 10^{12} hbar s^{-1}，并给出了B^0寿命的初步结果，τ（B^0）= 1.55+/-0.05+/-0.07 ps和τ（B^0）= 1.62+/-0.02+/-0.09 ps，它们是由B^0的两个衰变过程B^0-->D^{*-}pi^+和B^0-->D^{*-} l^+ nu_l的部分重建得到的。
tau physics at B-factories
今天，B工厂BaBar和Belle已经积累了最大的tau-tau事件样本，并正在竞争被称为tau-factories。BaBar和Belle要测试和测量的问题包括τ衰变中CP和CPT不变性的检查，奇异和非奇异谱函数的测量，奇异夸克和|V_us|质量的提取，轻子味破坏过程的搜索。本文综述了这两个实验的最新结果以及未来几年内将要进行的测量。
b to s transitions are flavour-changing neutral current (FCNC) processes that play an important role in the search for physics beyond the Standard Model (SM). Contributions from virtual particles in the loop are predicted to deviate observables, such as the branching fraction, from their SM expectations. Using data from the BaBar experiment, we present the first search for the rare decay B to K tau tau. The BABAR results on the measurement of the angular asymmetries of B to Kstar l l, where l is an electron or muon, are also reported. In addition, using a time-dependent analysis of B to KS0 pi…
New Results on Leptonic B meson decays at BaBar
我们从BaBar实验中选取了一些关于轻子B介子衰变的新结果：寻找衰变B 0->l+l-，B+->l+nu和B 0->l+tau-，以及B->Knunubar，其中l=e或mu.衰变模式也暗示了它们的电荷共轭。我们没有观察到这些衰变的证据，并对它们的分支分数设定了上限。
Since 1999, the B-factories collaborations BaBar and Belle have accumulated and studied large samples of tau lepton pairs. We summarize in the following the most interesting recent results.
The BABAR collaboration has demonstrated the first application of the new Tau Polarimetry technique. This polarimetry technique exploits the kinematic coupling of $τ$ decay products to the spin states of the $τ$ and initial state electron, to precisely determine the average beam polarization in an $e^+e^-$ collider. The Tau Polarimetry technique is expected to be used at Belle II following an upgrade to a polarized electron beam, where the precision with which the average beam polarization is known is expected to be the dominant systematic uncertainty in proposed future measurements which requ…
A Search for B- -> tau- nu-bar Recoiling Against a Fully Reconstructed B
我们在SLAC PEP-II非对称B工厂的BaBar探测器Y（4S）共振处收集的82 fb^（-1）数据样本中搜索B-> τ-nu-bar衰变。通过选择具有一个完全重建的B的事件样本来抑制连续性和组合背景。分析事件中另一个B的衰变产物，以寻找B-> τ- nu-bar衰变。τ轻子在下列衰变通道中被识别：τ->e，τ->mu，τ->pi，τ->pi pi 0 nu，τ-> pi pi nu。我们找不到信号的证据，设定90% C. L。BR（B-> τ nu）的上限< 7.7x10^（-4）。我们将这个结果与另一个BaBar测量相结合，在半轻子通道中重建一个B介子的样品中寻找B-> τ-nu-bar衰变。这两个样本在统计上是独立的。我们获得了90%的C.L. BR（B-> τ nu）的上限< 4.1x10^（-4）。所有结果都是初步的。
Rare Radiative and Leptonic B Decays: Recent Results from BABAR and Belle
评述了最近BABAR和Belle关于涉及光子或轻子对的稀有B衰变的研究结果。新的初步限制，从这两个实验的B--> ρ γ和B--> ω γ，并从BABAR的B --> K nu nu和B --> τ nu。还总结了过去一年的Belle对B->Xs 1 + 1-和B 0->K2（1430）γ的测量，BABAR对B->Xs γ的初步测量，以及BABAR和Belle对B->K（*）1 + 1-的初步结果。目前还没有发现与标准模型预测的重大偏差。
The Belle and Babar experiments have measured the branching fractions for B+ -> tau+ nu and Ds+ -> mu+ nu decays. From these measurements one can extract the B+ and Ds+ decay constants, which can be compared to lattice QCD calculations. For the Ds+ decay constant, there is currently a 2.1 sigma difference between the calculated value and the measured value.
Study of the tau- -> 3h- 2h+ nu-tau Decay
用BaBar探测器对τ →> 3 h-2 h +nu衰变（h= pi，K$）的分支分数的初步测量发现为{8.52 +/- 0.09 +/- 0.40} × 10 ~（-4），其中第一个误差是统计的，第二个是系统的。数据显示，有证据表明rho共振在τ轻子衰变为五个带电强子的过程中发挥着重要作用。
Measurement of the tau- --> K- pi0 nu_tau Branching Fraction
利用位于斯坦福直线加速器中心（SLAC）的PEP-Ⅱ e+ e对撞机上的BABAR探测器在质心能量sqrt{s}接近10.58 GeV时记录的230.2 fb-1的数据，测量了τ-> K-π 0 nu-τ分支分数。我们测量BF（tau-> K-pi 〇 nu_tau）=（0.416 +/-0.003（stat）+/-0.018（syst））%。
Both the B-factories BaBar and Belle have ended data-taking and have mostly completed the data analysis aimed at searching Lepton Flavor Violation in Tau decays. No evidence of LFV in tau decays has been found yet. We review in the following the experimental upper limits that have been set.
We report an analysis of tau- decaying into omega.pi-.nu_tau with omega -> pi+pi-pi0 using a data sample containing nearly 320 million tau pairs collected with the BABAR detector at the PEP-II B-Factory. We find no evidence for second-class currents and we set an upper limit of 0.69% at 90% confidence level for the fraction of second-class currents in this decay mode.
Experimental studies of B -> D^(*) tau nu decays, are reported. The results are based on large data samples collected at the Upsilon(4S) resonance with the Belle detector at KEKB and the BABAR detector at the SLAC PEP-II asymmetric energy e^+ e^- colliders.
Search for Second-Class Currents in tau- -> omega pi- nu_tau
我们报告的$τ^-$衰变成$ωπ^-ν_τ$与$ω\toπ^+π^-π^0$使用的数据包含近3.2亿tau对收集的BABAR探测器在PEP-II不对称能量$B$ -工厂的分析。我们没有发现第二类电流的证据，并在90%的置信水平下将第二类电流与第一类电流之比的上限设定为0.69%。
Electro-Weak Penguin and Leptonic Decays in BaBar
电弱企鹅衰变和轻子衰变为标准模型之外的物理提供了一个间接的探针，并有助于确定标准模型的参数。大量的B介子在B工厂生产允许精确测量的电弱企鹅衰变和轻子衰变的搜索。本文综述了BaBar实验中b -> s（d）γ、B^0 -> D^{*0} γ、b -> sl ^+ l^-以及最后的B-> τ nu衰变的现状。
Searches for $D^0$-$\bar{D^0}$ Mixing, Rare Charm and Tau Decays
我讨论的结果$D^{0}$ - $\bar{D}^{0}$混合通过强子以及半轻子的魅力衰变，罕见的变味中性电流的魅力部门和轻子味违反$τ$衰变到带电的轻轻子。本文综述了BABAR和Belle的结果。
We report recent results for lepton flavor violating (LFV) tau decays obtained at Belle and BaBar with the world-largest data samples.
Search for Lepton Flavor Violation in the Decay tau -> electron gamma
我们用位于PEP-II储存环上的BABAR探测器收集到的2.07 x 10^8 e+e- -> tau+ tau-事件，在质量中心能量接近10.58 GeV的情况下，对τ->电子γ衰变中轻子味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，BR（τ->电子γ）的分支比的上限为< 1.1 x 10^-7。
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。
A Search for B+ --> tau+ nu Recoiling Against B- --> D0 l- nu X
我们提出了一个搜索的衰变$B^{+} \to τ^{+} ν_τ$在$88.9 \times 10^{6}$ $Υ(4S)$衰变记录与BABAR探测器在SLAC $B$ -工厂。一个半排他的半轻子B衰变（$B^{-} \to D^{0} \ell^{-} \bar{ν_{\ell}}X$）的样本，其中$X$要么是光子，要么是$π^{0}$，要么什么都不是，被用来识别在每个事件中与另一个$B$介子相关的子粒子。我们在这些粒子中寻找单叉轻子$B^{+} \to τ^{+} ν_τ$衰变的证据。对于该数据样本，我们将$\mathcal{B}(B^{+} \to τ^{+} ν_τ) < 4.9 \times 10^{-4}$的分支分数的初步上限设定为90%置信水平。然后将该结果与$B^{+} \to τ^{+} ν_τ$的统计独立BABAR搜索组合，以给出组合的初步限值$\mathcal{B}(B^{+} \to τ^{+} ν_τ) < 4.1 \times 10^{-4}$。
Searches for lepton-flavor-violating decay of a tau lepton to a lighter mass lepton and a photon have been performed with the entire dataset of (963 +- 7) x 10^6 tau decays collected by the BaBar detector near the Upsilon(4S), Upsilon(3S) and Upsilon(2S) resonances. The searches yield no evidence of signals and we set upper limits on the branching fractions of BR(tau -> e gamma) < 3.3 x 10^-8 and BR(tau -> mu gamma) < 4.4 x 10^-8 at 90% confidence level.
Lepton Universality, |V_{us}| and search for second class current in tau decays
在SLAC国家加速器实验室的PEP-II e+e对撞机上，已经用BaBar探测器研究了数亿个τ衰变。荷电轻子普适性的最新结果和两个独立的|V_{us}|利用τ- -> e- nubar nu、mu- nubar nu、pi- nu、K- nu和KS 0 pi- nu衰变，在τ- -> pi- omega nu衰变中寻找第二类电流，其中还包含电荷共轭衰变模式。
Measurement of the B^0 meson properties using partially reconstructed B^0 to D^{*-}pi^+ and B^0 to D^{*-}l^+nu decays with the BABAR detector
本文利用PEP-Ⅱ储存环上BABAR探测器采集的数据，用部分重建技术研究了B^0的两个衰变过程B^0 --> D ^{*-}pi^+和B^0 --> D^{*-}l^+nu。为了增加统计量，只有来自衰变D^{*-} --> pi^-D^0的软π ^-被用于与带相反电荷的高动量π介子或轻子相关联。然后通过利用Y（4S）衰变的简单运动学的约束来识别事件。在每种情况下都获得了清晰的签名。B^0衰变点的位置由重建的π ^+（l^+）π ^-顶点得到。还确定了另一个抗B^0抗体在事件中的位置。利用PEP-Ⅱ的非对称束流能量对Y（4S）系统的增强作用，从束流方向上两个顶点之间的距离测量了B^0介子的寿命.对于B^0 --> D^{*-}pi^+和B^0 --> D ^{*-}l^+nu通道，初步结果分别为tau_B0 = 1.55+/-0.05+/-0.07 ps和tau_B0 = 1.62+/-0.02+/-0.09 ps。
We report a search for CP violation in the decay τ- -> π- \K^0_S (>= 0 π0) ν_τ using a dataset of 437 million τ lepton pairs, corresponding to an integrated luminosity of 476 fb^{-1}, collected with the BABAR detector at the PEP-II asymmetric energy e+e- storage rings. The CP-violating decay-rate asymmetry is determined to be (-0.45 +/- 0.24 +/- 0.11)%, approximately three standard deviations from the Standard Model prediction of (0.33 +/- 0.01)%.
We report an update to our previous measurement of the CKM element $|V_{ub}|$ using exclusive $B \rightarrow π\ell ν$ decays. In the charm sector we have performed a measurement of $f_{Ds}$ using $D_s\rightarrowτ^+ν_τ$ decays, we have measured the mixing parameter $y_{CP}$ using the lifetime ratio $\frac{\langleτ_{Kπ}\rangle}{\langleτ_{hh}\rangle}$ in $D^0$ decays, and we have also searched for CP violation using T-odd correlations in $D^0$ decays to $K^+K^-π^+π^-$. Finally, in the tau sector we have performed a search for the lepton flavor violating decays $τ^\pm \rightarrow e^\pm γ$ and $τ^\…
Observation of the Semileptonic Decays B --> D* tau nubar and Evidence for B --> D tau nubar
我们测量了半轻子衰变B-> D 0 τ- nubar，B-> D*0 τ- nubar，B 0 bar--> D+ τ- nubar和B 0 bar--> D*+ τ- nubar，它们对非标准模型振幅可能敏感.数据样本包括用BaBar探测器收集的232x10^6 Upplane（4S）--> BBbar衰变。通过对B-和B 0 bar通道的组合拟合，我们获得了分支分数B（B --> D τ-努巴）=（0.86 +/- 0.24 +/- 0.11 +/- 0.06）%和B（B --> D* τ- nubar）=（1.62 +/- 0.31 +/- 0.10 +/- 0.05）%（针对B 0 bar标准化），其中不确定性与统计、系统和标准化模式相关。
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.
We present recent BABAR results on searches for dark photons, long-lived scalar particles and new pi0-like particles.
Study of the tau- --> 3h-2h+nu Decay
用BaBar探测器测量τ-> 3 h-2 h + nu衰变的分支分数（h= pi，kaon）为（8.56 +/- 0.05 +/- 0.42）E-04，其中第一个误差是统计误差，第二个误差是系统误差。观察到的这种衰变的结构是显着不同的相空间预测，与rho共振起着很大的作用。观察到衰变τ-> f1 π nu，其中f1介子衰变为4个带电π介子，测量到分支分数为（3.9 +/- 0.7 +/- 0.5）E-04。
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