We report results from an updated study of the suppressed decays B- to D K- and B- to D* K- followed by D to K+pi-, where D(*) indicates a D(*)0 or an anti-D(*)0 meson, and D* decays to D pi0 or D gamma. These decays are sensitive to the CKM unitarity triangle angle gamma, due to interference between the b to c transition B- to D(*)0K- followed by the doubly Cabibbo-suppressed decay D0 to K+pi-, and the b to u transition B- to anti-D(*)0K- followed by the Cabibbo-favored decay anti-D0 to K+pi-. We also report an analysis of the decay B- to D(*)pi- with the D decaying into the doubly Cabibbo-suppressed mode D to K+pi-. Our results are based on 467 million Upsilon (4S) to B anti-B decays collected with the BaBar detector at SLAC. We measure the ratios R(*) of the suppressed ([K+pi-]_D K-/pi-) to favored ([K-pi+]_D K-/pi-) branching fractions as well as the CP asymmetries A(*) of those modes. We see indications of signals for the B- to D K- and B- to D*K-, D*->D pi0 suppressed modes, with statistical significances of 2.1 and 2.2 sigma, respectively, and we measure: R_{DK} = (1.1 \pm 0.6 \pm 0.2) \times 10^{-2}, A_{DK} = -0.86 \pm 0.47 \ ^{+0.12}_{-0.16}, R*_{(D pi0)K} = (1.8 \pm 0.9 \pm 0.4) \times 10^{-2}, A*_{(D pi0)K} = +0.77 \pm 0.35 \pm 0.12, R*_{(D gamma)K} = (1.3 \pm 1.4 \pm 0.8 ) \times 10^{-2}, A*_{(D gamma)K} = +0.36 \pm 0.94\ ^{+0.25}_{-0.41}, where the first uncertainty is statistical and the second is systematic. We use a frequentist approach to obtain the magnitude of the ratio r_B = |A(B- to anti-D0 K-) / A(B- to D0K-)|= (9.5^{+5.1}_{-4.1})%, with r_B<16.7% at 90% confidence level. In the case of B- to D* K- we find r*_B = |A(B^- to anti-D*0 K-)/A(B- to D*0 K-)|=(9.6^{+3.5}_{-5.1})%, with r*_B<15.0% at 90% confidence level.
英文摘要：
We report results from an updated study of the suppressed decays B- to D K- and B- to D* K- followed by D to K+pi-, where D(*) indicates a D(*)0 or an anti-D(*)0 meson, and D* decays to D pi0 or D gamma. These decays are sensitive to the CKM unitarity triangle angle gamma, due to interference between the b to c transition B- to D(*)0K- followed by the doubly Cabibbo-suppressed decay D0 to K+pi-, and the b to u transition B- to anti-D(*)0K- followed by the Cabibbo-favored decay anti-D0 to K+pi-. We also report an analysis of the decay B- to D(*)pi- with the D decaying into the doubly Cabibbo-suppressed mode D to K+pi-. Our results are based on 467 million Upsilon (4S) to B anti-B decays collected with the BaBar detector at SLAC. We measure the ratios R(*) of the suppressed ([K+pi-]_D K-/pi-) to favored ([K-pi+]_D K-/pi-) branching fractions as well as the CP asymmetries A(*) of those modes. We see indications of signals for the B- to D K- and B- to D*K-, D*->D pi0 suppressed modes, with statistical significances of 2.1 and 2.2 sigma, respectively, and we measure: R_{DK} = (1.1\pm 0.6 \pm 0.2)\times 10^{-2}, A_{DK} = -0.86 \pm 0.47 \ ^{+0.12}_{-0.16}, R*_{(D pi0)K} = (1.8\pm 0.9 \pm 0.4)\times 10^{-2}, A*_{(D pi0)K} = +0.77 \pm 0.35\pm 0.12, R*_{(D gamma)K} = (1.3\pm 1.4\pm 0.8 )\times 10^{-2}, A*_{(D gamma)K} = +0.36 \pm 0.94\ ^{+0.25}_{-0.41}, where the first uncertainty is statistical and the second is systematic. We use a frequentist approach to obtain the magnitude of the ratio r_B = |A(B- to anti-D0 K-) / A(B- to D0K-)|= (9.5^{+5.1}_{-4.1})%, with r_B<16.7% at 90% confidence level. In the case of B- to D* K- we find r*_B = |A(B^- to anti-D*0 K-)/A(B- to D*0 K-)|=(9.6^{+3.5}_{-5.1})%, with r*_B<15.0% at 90% confidence level.
Search For Charged Higgs Decays of the Top Quark Using Hadronic Decays of the Tau Lepton
这封信描述了费米实验室的对撞机探测器记录的在sqrt（s）=1.8 TeV的质子-反质子碰撞中产生带电希格斯玻色子的直接搜索。对标准模型的双希格斯二重态扩展预言了带电希格斯玻色子的存在。在这样的模型中，顶夸克B（t --> Hb--> tau nu b）的分支分数可能很大。这项研究利用了τ轻子在这个通道中的强子衰变，大大扩展了以前对带电希格斯粒子产生的限制。
Search for Nucleon Decay with Final States l+ eta, nubar eta, and nubar pi+,0 Using Soudan 2
我们用Soudan 2型铁跟踪量能器4.4千吨年的基准曝光量研究了核子衰变成5个两体末态的过程。对于质子衰变到完全可见的最终状态mu+ eta和e+ eta，我们观察到零和一个事件，分别满足我们的搜索标准的核子衰变。因此，在90%置信水平下，寿命下限（tau/B）为89 x 10^30年和81 x 10^30年。对于中子衰变到nubar η，我们得到寿命下限为71 × 10^30年。还报告了中子衰变成nubar pi 0和质子衰变成nubar pi+的极限。
Searches for a heavy scalar boson H decaying to a pair of 125 GeV Higgs bosons hh or for a heavy pseudoscalar boson A decaying to Zh, in the final states with h to tau tau
我们利用KEKB e^+e^-对撞机Belle探测器收集的87.1 fb^{-1}数据样本，寻找了无中微子τ轻子衰变为三个带电轻子的过程。由于信号候选事件的数量与从背景中预期的数量一致，因此对于各种衰减模式tau -> l l l，我们将分支分数的90%置信水平上限设置在（1.9-3.5）x 10^{-7}的范围内，其中l表示e或mu。
Search for the Invisible Decay of $\jpsi$ in $ψ(2S)\toπ+π^-J/ψ$
使用14.0百万个$ψ(2S) events collected with the BES-II detector, a search for the decay of the $ \jpsi $ to an invisible final state in $ \psipto $ is performed. The $ \jpsi $ peak in the distribution of mass recoiling against the $ π^+π^- $ is used to tag $ $ invisible decay. No signal is found, and an upper limit at the 90% confidence level is determined to be $ 1.2 \times 10^{-2} $ for the ratio $ \frac{{\cal B}(\jpsi\ar {invisible})}{{\cal B}(\jpsi\arμ^+μ^-)} $. This is the first search for $ J/J $衰减到不可见的最终状态。
在斯坦福直线加速器中心，使用与PEP-II对撞机耦合的BABAR探测器，对衰变B+ -> a0+ pi 0以及a0+衰变到eta和pi+进行了搜索。该分析使用的数据样本包括在Upperdance（4S）共振处收集的约2.52亿个BBbar对。未观察到信号，分支分数的90%置信水平上限设定为1.32 x 10^{-6}。
