122692764
Measurement of charm and beauty photoproduction at HERA using D* mu correlations
A measurement of charm and beauty photoproduction at the electron proton collider HERA is presented based on the simultaneous detection of a D*± meson and a muon. The correlation between the D* meson and the muon serves to separate the charm and beauty contributions and the analysis provides comparable sensitivity to both. The total and differential experimental cross sections are compared to LO and NLO QCD calculations. The measured charm cross section is in good agreement with QCD predictions including higher order effects while the beauty cross section is higher.
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.
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.
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.
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−
116899288
Inclusive Hadronic Results at BaBar: ISR and Pentaquark Searches
We present recent measurements of hadronic cross-sections from the BaBar experiment and report preliminary results on searches for pentaquark states. Studies of hadronic cross-sections using initial-state radiation offer promising prospects at BaBar. Many exclusive channels have already been measured, and more are in progress. A fully inclusive analysis should also offer a precise measurement of {Delta}{alpha}{sub QED}{sup Had}. Searches for pentaquark states have so far been negative, but they have served to highlight the potential for the study of charmed and non-charmed baryons at high-luminosity e{sup +}e{sup -} colliders.
7550105
Prospects for R measurement at BABAR using radiative return
A precise measurement of the ratio of hadron to muon production in e{sup +}e{sup -} collisions, denoted by R(s), is a necessary input for the interpretation of current precision electroweak measurements. We describe a method for measuring R(s) with the BaBar detector at the PEP-II B-factory using initial-state radiation events.
118951342
Studies of e+e− Collisions with a Hard Initial‐State Photon at BaBar
We present preliminary BaBar measurements of hadronic cross sections in e+e- annihilation using the radiative return technique. The cross sections for e+e- {yields} pp-bar, 3({pi}+{pi}-), 2({pi}+{pi}-)2{pi}0, and K+K-2({pi}+{pi}-) are measured. Measurements of the proton form factor and of the ratio GE/GM are also shown.