The search for events containing isolated leptons (electrons or muons) and missing transverse momentum produced in e^{\pm}p collisions is performed individually and in a common phase space with the H1 and ZEUS detectors at HERA in the period 1994--2007. The presented H1+ZEUS data sample corresponds to an integrated luminosity of 0.97 fb^{-1}, and comprises the complete high energy data from the HERA programme. A total of 87 events are observed in the data, compared to a Standard Model prediction of 92.7 \pm 11.2. At large hadronic transverse momentum P_{T}^{X} > 25 GeV in the e^{+}p data, luminosity 0.58 fb^{-1}, 23 data events are observed compared to a SM prediction of 14.6 \pm 1.9. Production cross section measurements of events containing isolated leptons and missing transverse momentum and of single W production are performed by H1, where the measured cross sections are found to be in agreement with SM predictions. A complementary search by H1 for events containing an isolated tau lepton and missing P_{T} is also presented. A measurement of the W polarisation fractions is performed by H1, where the presented results are found to be in agreement with the SM. Finally, the H1 isolated lepton events are examined in the context of a search for anomalous single top production. In the absence of a clear signal, an upper limit on the anomalous top production cross section σ_{ep\to etX} < 0.16 pb is established at the 95% confidence level, corresponding to a limit an upper bound on the anomalous magnetic coupling κ_{tuγ} < 0.14.
To resolve the long-standing discrepancy between the precision measurement of bottom quark forward-backward asymmetry at LEP/SLC and the Standard Model prediction, we propose a novel method to probe the $Zb\bar{b}$ coupling by measuring the single-spin asymmetry $A_e^b$ of the polarized lepton cross section in neutral current DIS processes with a $b$-tagged jet at HERA and EIC. Depending on the tagging efficiency of the final state $b$-jet, the measurement of $A_e^b$ at HERA can already partially break the degeneracy found in the anomalous $Zb\bar{b}$ coupling, as implied by the LEP and SLC pr…
Diffractive Open Charm Production in Deep-Inelastic Scattering and Photoproduction at HERA
测量的衍射开放魅力生产HERA。事件拓扑由ep -> eX Y给出，其中系统X包含至少一个粲强子，并且与领先的低质量质子残留系统Y有很大的快度间隙。两种分析技术用于截面测量。在第一种方法中，通过重建D*（2010）介子来标记粲夸克。该技术用于深度非弹性散射（DIS）和光生。第二种方法是基于主顶点的径迹位移来测量DIS中包含衍射截面的开粲贡献，并将测量结果与基于衍射部分子密度函数的次高阶QCD预言进行了比较，所述衍射部分子密度函数是从H1处包含衍射截面的QCD分析中获得的。一个很好的协议，观察到在整个运动学制度，这支持的有效性QCD因子分解的开放的魅力生产衍射DIS和光生。
We present measurements of the tWb coupling form factors using information from electroweak single top quark production and from the helicity of W bosons from top quark decays in ttbar events. We set upper limits on anomalous tWb coupling form factors using data collected with the D0 detector at the Tevatron ppbar collider corresponding to an integrated luminosity of 5.4 fb^-1.
We give a simple physical argument to understand the observation that the angular distribution of the top decay lepton depends only on the polarisation of the top and is independent of any anomalous $tbW$ coupling to linear order.
The amount of data collected by the CMS experiment at the CERN LHC in the second data taking period provides the possibility to study absolute and differential cross sections of top quark interaction processes with high precision. Utilizing these results, fundamental standard model parameters such as the top quark mass are extracted. Moreover, given standard model measurements are interpreted in the context of Beyond the standard model theories. Recent results on top quark properties and rare or anomalous top quark interactions by CMS are presented in these proceedings. Furthermore, the implic…
