118108911
Research Proposal for an Experiment to Search for the Decay $\mu \to eee$
We propose an experiment (Mu3e) to search for the lepton flavour violating decay mu+ -> e+e-e+. We aim for an ultimate sensitivity of one in 10^16 mu-decays, four orders of magnitude better than previous searches. This sensitivity is made possible by exploiting modern silicon pixel detectors providing high spatial resolution and hodoscopes using scintillating fibres and tiles providing precise timing information at high particle rates.
120101281
The Mu3e Experiment
Abstract The Mu3e experiment is designed to search for charged lepton flavour violation in the process μ + → e + e − e + with a branching ratio sensitivity of 10 − 16 . This requires a detector capable of coping with rates of up to 2 ⋅ 10 9 muons/s whilst being able to reduce backgrounds from accidental coincidences and the process μ + → e + e − e + ν ¯ μ ν e to below the 10 − 16 level. The use of 50 μ m thin high-voltage monolithic active pixel sensors in conjunction with an innovative tracking concept provide the momentum and position resolution necessary, whilst the timing resolution is provided by a combination of scintillating fibres and tiles. The recently approved Mu3e experiment will be located at the Paul Scherrer Institute in Switzerland and is currently preparing for detector construction.
119113295
Measurement of isolated photon production in deep-inelastic scattering at HERA
The production of isolated photons in deep-inelastic scattering ep→eγX is measured with the H1 detector at HERA. The measurement is performed in the kinematic range of negative four-momentum transfer squared 4<Q2<150 GeV2 and a mass of the hadronic system WX>50 GeV. The analysis is based on a total integrated luminosity of 227 pb-1. The production cross section of isolated photons with a transverse energy in the range 3<ETγ<10 GeV and pseudorapidity range -1.2<ηγ<1.8 is measured as a function of ETγ, ηγ and Q2. Isolated photon cross sections are also measured for events with no jets or at least one hadronic jet. The measurements are compared with predictions from Monte Carlo generators modelling the photon radiation from the quark and the electron lines, as well as with calculations at leading and next to leading order in the strong coupling. The predictions significantly underestimate the measured cross sections.
18175820
Measurement and QCD analysis of the diffractive deep-inelastic scattering cross section at HERA
A detailed analysis is presented of the diffractive deep-inelastic scattering process ep→eXY, where Y is a proton or a low mass proton excitation carrying a fraction 1-xIP>0.95 of the incident proton longitudinal momentum and the squared four-momentum transfer at the proton vertex satisfies |t|<1 GeV2. Using data taken by the H1 experiment, the cross section is measured for photon virtualities in the range 3.5≤Q2≤1600 GeV2, triple differentially in xIP, Q2 and β=x/xIP, where x is the Bjorken scaling variable. At low xIP, the data are consistent with a factorisable xIP dependence, which can be described by the exchange of an effective pomeron trajectory with intercept αIP(0)=1.118±0.008(exp.)+0.029-0.010(model). Diffractive parton distribution functions and their uncertainties are determined from a next-to-leading order DGLAP QCD analysis of the Q2 and β dependences of the cross section. The resulting gluon distribution carries an integrated fraction of around 70% of the exchanged momentum in the Q2 range studied. Total and differential cross sections are also measured for the diffractive charged current process e+p→ν̄eXY and are found to be well described by predictions based on the diffractive parton distributions. The ratio of the diffractive to the inclusive neutral current ep cross sections is studied. Over most of the kinematic range, this ratio shows no significant dependence on Q2 at fixed xIP and x or on x at fixed Q2 and β.
122573727
Results from the Beijing Spectrometer III
The new BES III detector at BEPCII collected 106 million ψ and about 226 million J/ψ events in 2009. Results based on these samples are reported, including branching ratios for χXcJ → π0π0,ηη, 4π0, γyV and VV, where V is a ρ, ω, or Φ as well as first measurements of the branching ratios for ψ → γ0hc and hc → γηc and measurements of the mass and width of the hc. Results in hadron spectroscopy include the confirmation of the pp threshold enhancement in J/ψ→γpp and confirmation of the X(1835) in J/ψ→γηπ+π−
62672040
Partial wave analysis at BES III harnessing the power of GPUs
Partial wave analysis (PWA) is a core tool for determining resonance properties in hadron spectroscopy. The unbinned likelihood fits employed are however computationally very expensive especially in view of the very large data samples being collected at the Beijing Spectrometer (BES) III experiment and expected from future experiments such as Glue‐X and PANDA. Using the power of massively parallel floating point calculations on graphics processing units (GPUs), we have managed to speed up PWA by more than two orders of magnitude compared to legacy implementations. The resulting software framework allows for the fast creation and running of PWA code. Modern hardware and software thus solve the PWA speed problems—many questions concerning fit methods and especially the reliability of fit results however remain open.
109931424
Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC
Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H --> gamma-gamma, H --> ZZ* --> 4 leptons and H --> WW --> 2 leptons + 2 neutrinos. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of 7 TeV and 8 TeV, corresponding to an integrated luminosity of about 25/fb. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson.
17481766
A Measurement of CP violating asymmetries in $B^0 \to$ f0(980) $K^0_{s}$ decays
We present preliminary measurements of the CP -violating asymmetries in the decay B → f0(980)(→ π+π−)K0 S . The results are obtained from a data sample of 209 × 10 Υ (4S) → BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. From a time-dependent maximum-likelihood fit we measure the mixing-induced CP violation parameter S = −0.95 −0.23 ± 0.10 and the direct CP violation parameter C = −0.24 ± 0.31 ± 0.15, where the first errors are statistical and the second systematic. Submitted to the 32 International Conference on High-Energy Physics, ICHEP 04, 16 August—22 August 2004, Beijing, China Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309 Work supported in part by Department of Energy contract DE-AC03-76SF00515. The BABAR Collaboration, B. Aubert, R. Barate, D. Boutigny, F. Couderc, J.-M. Gaillard, A. Hicheur, Y. Karyotakis, J. P. Lees, V. Tisserand, A. Zghiche Laboratoire de Physique des Particules, F-74941 Annecy-le-Vieux, France A. Palano, A. Pompili Università di Bari, Dipartimento di Fisica and INFN, I-70126 Bari, Italy J. C. Chen, N. D. Qi, G. Rong, P. Wang, Y. S. Zhu Institute of High Energy Physics, Beijing 100039, China G. Eigen, I. Ofte, B. Stugu University of Bergen, Inst. of Physics, N-5007 Bergen, Norway G. S. Abrams, A. W. Borgland, A. B. Breon, D. N. Brown, J. Button-Shafer, R. N. Cahn, E. Charles, C. T. Day, M. S. Gill, A. V. Gritsan, Y. Groysman, R. G. Jacobsen, R. W. Kadel, J. Kadyk, L. T. Kerth, Yu. G. Kolomensky, G. Kukartsev, G. Lynch, L. M. Mir, P. J. Oddone, T. J. Orimoto, M. Pripstein, N. A. Roe, M. T. Ronan, V. G. Shelkov, W. A. Wenzel Lawrence Berkeley National Laboratory and University of California, Berkeley, CA 94720, USA M. Barrett, K. E. Ford, T. J. Harrison, A. J. Hart, C. M. Hawkes, S. E. Morgan, A. T. Watson University of Birmingham, Birmingham, B15 2TT, United Kingdom M. Fritsch, K. Goetzen, T. Held, H. Koch, B. Lewandowski, M. Pelizaeus, M. Steinke Ruhr Universität Bochum, Institut für Experimentalphysik 1, D-44780 Bochum, Germany J. T. Boyd, N. Chevalier, W. N. Cottingham, M. P. Kelly, T. E. Latham, F. F. Wilson University of Bristol, Bristol BS8 1TL, United Kingdom T. Cuhadar-Donszelmann, C. Hearty, N. S. Knecht, T. S. Mattison, J. A. McKenna, D. Thiessen University of British Columbia, Vancouver, BC, Canada V6T 1Z1 A. Khan, P. Kyberd, L. Teodorescu Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom A. E. Blinov, V. E. Blinov, V. P. Druzhinin, V. B. Golubev, V. N. Ivanchenko, E. A. Kravchenko, A. P. Onuchin, S. I. Serednyakov, Yu. I. Skovpen, E. P. Solodov, A. N. Yushkov Budker Institute of Nuclear Physics, Novosibirsk 630090, Russia D. Best, M. Bruinsma, M. Chao, I. Eschrich, D. Kirkby, A. J. Lankford, M. Mandelkern, R. K. Mommsen, W. Roethel, D. P. Stoker University of California at Irvine, Irvine, CA 92697, USA C. Buchanan, B. L. Hartfiel University of California at Los Angeles, Los Angeles, CA 90024, USA S. D. Foulkes, J. W. Gary, B. C. Shen, K. Wang University of California at Riverside, Riverside, CA 92521, USA
104344849
Measurement of the CP-violating asymmetries in $B^0 \to K^0_{S} \pi^0$ and of the branching fraction of $B^0 \to K^0 \pi^0$
126364214
Study of $B^0$ (anti-B0) $\to \pi^0 \pi^0$, $B^\pm \to \pi^\pm \pi^0$ and $B^\pm \to K^\pm \pi^0$ decays