Search for narrow resonances in e+ e- annihilation between 1.85 and 3.1 GeV with the KEDR Detector

We report results of a search for narrow resonances in e+ e- annihilation at center-of-mass energies between 1.85 and 3.1 GeV performed with the KEDR detector at the VEPP-4M e+ e- collider. The upper limit on the leptonic width of a narrow resonance Gamma(R -> ee) Br(R -> hadr) < 120 eV has been obtained (at 90 % C.L.)

Measurement of \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-) and \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)

The products of the electron width of the J/\psi meson and the branching fraction of its decays to the lepton pairs were measured using data from the KEDR experiment at the VEPP-4M electron-positron collider. The results are \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-)=(0.3323\pm0.0064\pm0.0048) keV, \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)=(0.3318\pm0.0052\pm0.0063) keV. Their combinations \Gamma_{ee}\times(\Gamma_{ee}+\Gamma_{\mu\mu})/\Gamma=(0.6641\pm0.0082\pm0.0100) keV, \Gamma_{ee}/\Gamma_{\mu\mu}=1.002\pm0.021\pm0.013 can be used to improve theaccuracy of the leptonic and full widths and test leptonic universality. Assuming e\mu universality and using the world average value of the lepton branching fraction, we also determine the leptonic \Gamma_{ll}=5.59\pm0.12 keV and total \Gamma=94.1\pm2.7 keV widths of the J/\psi meson.Comment: 7 pages, 6 figure

Measurement of main parameters of the \psi(2S) resonance

A high-precision determination of the main parameters of the \psi(2S) resonance has been performed with the KEDR detector at the VEPP-4M e^{+}e^{-} collider in three scans of the \psi(2S) -- \psi(3770) energy range. Fitting the energy dependence of the multihadron cross section in the vicinity of the \psi(2S) we obtained the mass value M = 3686.114 +- 0.007 +- 0.011 ^{+0.002}_{-0.012} MeV and the product of the electron partial width by the branching fraction into hadrons \Gamma_{ee}*B_{h} = 2.233 +- 0.015 +- 0.037 +- 0.020 keV. The third error quoted is an estimate of the model dependence of the result due to assumptions on the interference effects in the cross section of the single-photon e^{+}e^{-} annihilation to hadrons explicitly considered in this work. Implicitly, the same assumptions were employed to obtain the charmonium leptonic width and the absolute branching fractions in many experiments. Using the result presented and the world average values of the electron and hadron branching fractions, one obtains the electron partial width and the total width of the \psi(2S): \Gamma_{ee} =2.282 +- 0.015 +- 0.038 +- 0.021 keV, \Gamma = 296 +- 2 +- 8 +- 3 keV. These results are consistent with and more than two times more precise than any of the previous experiments

Price assymetry in the Dutch retail gasoline market

This paper analyses retail price adjustments in the Dutch gasoline market. We estimate an asymmetric error correction model on weekly price changes for the years 1996 to 2001. We construct five datasets, one for each working day. The conclusions on asymmetric pricing are shown to differ over these datasets, suggesting that the choice of the day for which prices are observed matters more than commonly believed. In our view, the insufficient robustness of outcomes might explain the mixed conclusions found in the literature. Using two approaches, we also show that the effect of asymmetry on Dutch consumer costs is negligible

Modeling of GERDA Phase II data

The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta (0\u3bd\u3b2\u3b2) decay of 76Ge. The technological challenge of Gerda is to operate in a \u201cbackground-free\u201d regime in the region of interest (ROI) after analysis cuts for the full 100 kg\ub7yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around Q\u3b2\u3b2 for the 0\u3bd\u3b2\u3b2 search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos (2\u3bd\u3b2\u3b2) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for Gerda Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of 16.04 120.85+0.78\ub710 123 cts/(keV\ub7kg\ub7yr) for the enriched BEGe data set and 14.68 120.52+0.47\ub710 123 cts/(keV\ub7kg\ub7yr) for the enriched coaxial data set. These values are similar to the one of Phase I despite a much larger number of detectors and hence radioactive hardware components

Search for exotic physics in double-β decays with GERDA Phase II

A search for Beyond the Standard Model double-$\beta$ decay modes of$^{76}$Ge has been performed with data collected during the Phase II of theGERmanium Detector Array (GERDA) experiment, located at Laboratori Nazionalidel Gran Sasso of INFN (Italy). Improved limits on the decays involvingMajorons have been obtained, compared to previous experiments with $^{76}$Ge,with half-life values on the order of 10$^{23}$ yr. For the first time with$^{76}$Ge, limits on Lorentz invariance violation effects in double-$\beta$decay have been obtained. The isotropic coefficient$\mathring{a}_\text{of}^{(3)}$, which embeds Lorentz violation indouble-$\beta$ decay, has been constrained at the order of $10^{-6}$ GeV. Wealso set the first experimental limits on the search for light exotic fermionsin double-$\beta$ decay, including sterile neutrinos.<br

Growing of ZnWO₄ single crystals from melt by the low thermal gradient Czochralski technique

The shape formation regularities of ZnWO₄ scintillation crystals grown along the [001] and [010] directions by the low-temperature-gradient Czochralski technique have been studied. It has been established that increasing crystallization speed is accompanied by the development of faceted shapes at the crystallization front. The inclusion-free crystals can be grown with both completely rounded or completely faceted solid-liquid interface, while the coexistence of faceted and rounded surfaces may result in capturing inclusions at their boundaries. The inclusion-free ZnWO₄ crystals of 45 mm diameter and the length up to 150 mm have been grown. Absorption spectra of the crystals prior to and after annealing have been measured. For the samples of d40 and l=40 mm size, the energy resolution of 11 % for gamma radiation with the energy of 662 keV has been obtained.Досліджено закономірності формоутворення сцинтиляційних кристалів ZnWO₄ при їх рості низькоградієнтним методом Чохральського у напрямах [001] та [010]. Встановлено, що збільшення швидкості кристалізації супроводжується розвитком на фронті кристалізації огранованих форм. Кристали, вільні від включень, утворюються як при повністю округлому, так і при повністю ограненому фронті кристалізації, в той час як співіснування огранених та округлих форм може супроводжуватися захопленням включень на їхніх межах. Вирощено вільні від включень кристали ZnWO₄ діаметром 45 та довжиною до 150 мм. Виміряно спектри поглинання кристалів до та після їх відпалу. Для зразків d40 та l=40 мм одержано енергетичне розрішення 11 % для гамма-випромінювання з енергією 662 кеВ.Изучены закономерности формообразования сцинтилляционных кристаллов ZnWO₄ при их росте низкоградиентным методом Чохральского по направлениям [001] и [010]. Установлено, что повышение скорости кристаллизации сопровождается развитием на фронте кристаллизации гранных форм. Кристаллы, свободные от включений, образуются как при полностью округлом, так и при полностью гранном фронте кристаллизации, тогда как сосуществование гранных и округлых форм может сопровождаться захватом включений на их границах. Выращены свободные от включений кристаллы ZnWO₄ диаметром 45 и длиной до 150 мм. Измерены спектры поглощения кристаллов до и после их отжига. Для образцов размером d40 и длиной 40 мм получено энергетическое разрешение 11 % для гамма-излучения с энергией 662 keV