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The production of μe-pairs is studied in interactions of neutrinos with nuclei of heavy freon in the SKAT bubble chamber experiment. A rate of μ−e+ to charged current interactions above the charm threshold of\(R^{\mu ^ -e^ +}= (4.6 \pm 1.2) \cdot 10^{ - 3} \) is found. The properties of the observed μ−e+ events can be well described by assuming them to originate from the semileptonic decay of quasielastic produced charmed baryonsΛc and inclusive charmedD-meson production. The rates for these reactions are found to be (6.7±3.5)×10−2 and (2.5±0.9)×10−2, respectively. A total charmed particle production rate of (9.2±3.6)×10−2 is calculated.
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We present inclusive spectra of charged hadrons produced in\(\begin{array}{*{20}c}{( - )}\\v\\ \end{array}\)-Freon interactions at average beam energies of about 6 GeV. The experiment was done using the bubble chamber SKAT at the 70 GeV Serpukhov accelerator. In the hadronic energy range,W<5 GeV, dominantly isotropic events are found. The transverse momentum of the produced particles shows no strongW2-dependence. Feynman-scaling may be reached forW2≳10 GeV2, where also theż-spectra are described by the predictions of the parton model. All experimental data are reproduced rather well also by a Monte Carlo model based on ordinary phase space.
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We present the final results from the search for μe pairs produced in neutrino interactions using the freon filled bubble chamber SKAT. The rate of μ−e+ pairs to charged current events above the charm threshold is\(R_{\mu ^ -e^ +}= (4.8 \pm 1.1)10^{ - 3} \). Assuming charm particle production to be the origin of the positron we calculate\(R_{\Lambda _c^ +}= (6.2 \pm 3.1)10^{ - 2} \) andRD=(2.8±0.9)10−2. We observe no considerable μ−e− pair production above the background. In the regionEv>3 GeV,pμ,e>1.0 GeV/c andpμ>pe we find with a 90% confidence level the limit\(R_{\mu ^ -e^ -}< 1.7 10^{ - 4} \).
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We report charged-particle pair correlation analyses in the space of Delta -phi (azimuth) and Delta -eta (pseudo-rapidity), for central Au + Au collisions at sqrt{s_{NN}} = 200 GeV in the STAR detector. The analysis involves unlike-sign charge pairs and like-sign charge pairs, which are transformed into charge-dependent (CD) signals and charge-independent (CI) signals. We present detailed parameterizations of the data. A model featuring dense gluonic hot spots as first proposed by van Hove predicts that the observables under investigation would have sensitivity to such a substructure should it occur, and the model also motivates selection of transverse momenta in the range 0.8 < p_t < 2.0$ GeV/c. Both CD and CI correlations of high statistical significance are observed and possible interpretations are discussed.
FIG. 1: a) left side: The $\Delta\phi$ - $\Delta\eta$ correlation data for unlike-sign charge particle pairs from the Star central trigger dataset shown in a 2-dimensional (2-D) perspective plot. The particle tracks have 0.8 GeV/c < $p_t$ < 2.0 GeV/c and |$\eta$| < 1.0. The structure that looks like tiles on a roof is due to the readout boundary effects of the 12 sector TPC. b) right side: The similar correlation data for like-sign charge particle pairs is shown.
FIG. 1: a) left side: The $\Delta\phi$ - $\Delta\eta$ correlation data for unlike-sign charge particle pairs from the Star central trigger dataset shown in a 2-dimensional (2-D) perspective plot. The particle tracks have 0.8 GeV/c < $p_t$ < 2.0 GeV/c and |$\eta$| < 1.0. The structure that looks like tiles on a roof is due to the readout boundary effects of the 12 sector TPC. b) right side: The similar correlation data for like-sign charge particle pairs is shown.
FIG. 2: a) left side: The correlation data for the ratio of the histograms of same-event-pairs to mixed-event-pairs for unlike-sign charged pairs, shown in a two-dimensional (2-D) perspective plot $\Delta\phi$ - $\Delta\eta$. The plot was normalized to a mean of 1. b) right side: The similar correlation data for like-sign charge pairs.
We present the first comprehensive tests of light-lepton universality in the angular distributions of semileptonic $B^0$-meson decays to charged spin-1 charmed mesons. We measure five angular-asymmetry observables as functions of the decay recoil that are sensitive to lepton-universality-violating contributions. We use events where one neutral $B$ is fully reconstructed in $\Upsilon\left(4S\right)\to{}B \overline{B}$ decays in data corresponding to $189~\mathrm{fb}^{-1}$ integrated luminosity from electron-positron collisions collected with the Belle II detector. We find no significant deviation from the standard model expectations.
The NA61/SHINE experiment at the CERN SPS is performing a uniqe study of the phase diagram of strongly interacting matter by varying collision energy and nuclear mass number of colliding nuclei. In central Pb+Pb collisions the NA49 experiment found structures in the energy dependence of several observables in the CERN SPS energy range that had been predicted for the transition to a deconfined phase. New measurements of NA61/SHINE find intriguing similarities in p+p interactions for which no deconfinement transition is expected at SPS energies. Possible implications will be discussed.
Internal jet structure in dijet production in deep-inelastic scattering is measured with the H1 detector at HERA. Jets with transverse energies ET,Breit > 5 GeV are selected in the Breit frame employing k_perp and cone jet algorithms. In the kinematic region of squared momentum transfers 10 < Q2 <~ 120 GeV2 and x-Bjorken values 2.10^-4 <~ xBj <~ 8.10^-3, jet shapes and subjet multiplicities are measured as a function of a resolution parameter. Distributions of both observables are corrected for detector effects and presented as functions of the transverse jet energy and jet pseudo-rapidity. Dependences of the jet shape and the average number of subjets on the transverse energy and the pseudo-rapidity of the jet are observed. With increasing transverse jet energies and decreasing pseudo-rapidities, i.e.towards the photon hemisphere, the jets are more collimated. QCD models give a fair description of the data.
The dependence of the jet shapes on the transverse jet energy ET in the pseudorapidity range < 1.5 and the ET range 5 TO 8 GeV using the inclusive KT jet finding algorithm.
The dependence of the jet shapes on the transverse jet energy ET in the pseudorapidity range 1.5 TO 2.2 and the ET range 5 TO 8 GeV using the inclusive KT jet finding algorithm.
The dependence of the jet shapes on the transverse jet energy ET in the pseudorapidity range > 2.2 and the ET range 5 TO 8 GeV using the inclusive KT jet finding algorithm.
Results on $\phi$ meson production in inelastic p+p collisions at CERN SPS energies are presented. They are derived from data collected by the NA61/SHINE fixed target experiment, by means of invariant mass spectra fits in the $\phi \to K^+K^-$ decay channel. They include the first ever measured double differential spectra of $\phi$ mesons as a function of rapidity $y$ and transverse momentum $p_T$ for proton beam momenta of 80 GeV/c and 158 GeV/c, as well as single differential spectra of $y$ or $p_T$ for beam momentum of 40 GeV/c. The corresponding total $\phi$ yields per inelastic p+p event are obtained. These results are compared with existing data on $\phi$ meson production in p+p collisions. The comparison shows consistency but superior accuracy of the present measurements. The emission of $\phi$ mesons in p+p reactions is confronted with that occurring in Pb+Pb collisions, and the experimental results are compared with model predictions. It appears that none of the considered models can properly describe all the experimental observables.
Double differential multiplicity of $\phi$ mesons produced in minimum bias p+p collisions at beam momentum of 158 GeV/c, as a function of transverse momentum $p_T$ and rapidity $y$.
Double differential multiplicity of $\phi$ mesons produced in minimum bias p+p collisions at beam momentum of 80 GeV/c, as a function of transverse momentum $p_T$ and rapidity $y$.
Transverse momentum $p_T$ spectrum of $\phi$ mesons produced in minimum bias p+p collisions at beam momentum of 40 GeV/c, in a broad rapidity $y$ bin of (0, 1.5).
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