Charm dimuon production in neutrino-nucleon interactions in the NOMAD experiment

We present our new measurement of charm dimuon production in neutrino-iron interactions based upon the full statistics collected by the NOMAD experiment. After background subtraction we observe 15,340 charm dimuon events, providing the largest sample currently available. The analysis exploits the large inclusive charged current sample (about 9 million events after all analysis cuts) to constrain the total systematic uncertainty to ∼2%. The extraction of strange sea and charm production parameters is also discussed.     

Results from the mainz neutrino mass experiment

The presently lowest limit for the mass of the electron neutrino is m _ν<2.2 eV/c ² 95% C.L.) derived from measurements at Mainz up to 1999. The data taken in 2000 are not fully analyzed yet, but limits of possible distortions as reported by the Troitsk group can be given.     

Results from the forward G0 experiment

The G0 experiment is dedicated to the determination of the strange quark contribution to the electric and magnetic nucleon form factors for a large range of momentum transfers between 0.1 to 1(GeV/c)² . This information is provided by the asymmetries of cross-sections measured with longitudinally polarized electrons in elastic electron-proton scattering and quasi-elastic electron-deuteron scattering. A set of measurements at two different Q² will allow the complete separation of the electric and magnetic weak, as well as axial nucleon form factors. This report summarizes the physics case, gives details about the dedicated set-up used, and shows the results of the combination of the strange quark contribution in the electric and magnetic form factors of the protons. The experiment was performed at the Jefferson Laboratory, during years 2003 and 2004, and will be completed after backward-angle measurements in 2006, 2007.     

Results from the T2K experiment

The T2K (Tokai-to-Kamioka) experiment is a long baseline neutrino oscillation experiment designed to probe the θ ₁₃ neutrino mixing parameter by looking for the appearance of ν _e in an almost pure ν _μ beam. The concurrent measurement of the ν _μ disappearance allows refined measurements of the atmospheric Δm ² and θ ₂₃ mixing parameters.     

Results from the KGF proton decay experiment

Summary The data from the KGF experiment at the depth of 2.3 km underground are used to search for GUT signals in the form of nucleon decay oscillation and monopoles. Four events are considered as candidates for nucleon decay, whereas one plausible event is recorded to correspond to oscillation. Using different methods the monopole flux is shown to be <10⁻¹⁴ cm⁻² s⁻¹ sr⁻¹ for velocity range 10⁻³ c÷c. The angular distribution of cosmic-ray muons is used to derive an upper limit of 10⁻³ for the flux of prompt muons of energy up to a few hundred TeV in comparison to pions of same energy at production.

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Riassunto Si usano i dati dell'esperimento KGF alla profondità di 2.3 km sottoterra per ricercare segnali di GUT sotto forma di decadimento di nucleoni, oscillazioni e monopoli. Quattro eventi possono esser considerati come candidati per il decadimento di nucleoni, mentre si è registrato un evento che plausibilmente corrisponde all'oscillazione . Si mostra, con metodi diversi che il flusso di monopoli è <10⁻¹⁴ cm⁻¹ s⁻² sr⁻¹ nel-l'intervallo di velocità 10⁻³ c÷c. Si fa uso della distribuzione angolare dei muoni dei raggi cosmici per dedurre un limite superiore di 10⁻³ al flusso di muoni pronti di energia sino a qualche centinaio di TeV in rapporto ai pioni con la stessa energia di produzione.

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Резюме Данные, полученные в эксперименте Колар Голд Филдна глубине 2.3 км, анализируются с целью поиска эффектов, предсказываемых теориями Веяикого Обьединения: распада нуклона, осцилляций , магнитных монополей. 4 события могут рассматриваться как кандидаты на нуклонный распад, 1 событие-как кандидат на переход . С применением различных методов анализа показано, что поток монополей <10⁻¹⁴ см⁻² с⁻¹ стер⁻¹ для диапазона скоростей 10⁻³ с. Из углового распределения мюонов космических лучей получен верхний предел для потока мюонов непосредственной генерации с энергиями до нескольких сотен ТэВ. Этот поток не превышает 10⁻³ потока пионов с теми же начальными энергиями.

     

Results from STAR experiment at RHIC

We present some of the important experimental results from nucleus-nucleus collision studies carried out by the STAR experiment at Relativistic Heavy Ion Collider (RHIC). The results suggests that central Au+Au collisions at RHIC has produced a dense and rapidly thermalizing matter with initial energy densities above the critical values predicted by lattice QCD for establishment of a quark-gluon plasma (QGP).     

Results from the MUNU experiment on neutrino-electron scattering

The MUNU experiment studies electron antineutrino-electron elastic scattering. The detector is a time projection chamber surrounded by an anti-Compton detector. The distance between the reactor (serving as the neutrino source) and the detector is 18 m. Here, data are presented corresponding to 66.6-d live time reactor on and 16.7-d reactor off. The electron recoil spectrum obtained by using a visual scanning procedure is presented. The upper limit on the neutrino magnetic moment ν_π<1.0×10^?10π_B is derived.     

Search for the exotic Θ+ resonance in the NOMAD experiment

A search for exotic Θ⁺ baryon via Θ⁺→p+K⁰ _S decay mode in the NOMAD ν_μN data is reported. The special background generation procedure was developed. The proton identification criteria are tuned to maximize the sensitivity to the Θ⁺ signal as a function of x_F which allows to study the Θ⁺ production mechanism. We do not observe any evidence for the Θ⁺ state in the NOMAD data. We provide an upper limit on Θ⁺ production rate at 90% CL as 2.13×10^-3 per neutrino interaction. PACS 13.15.+g; 13.60.Le; 13.87.Fh; 14.40.Ev     

A study of strange particles produced in neutrino neutral current interactions in the NOMAD experiment

Results of a detailed study of strange particle production in neutrino neutral current interactions are presented using the data from the NOMAD experiment. Integral yields of neutral strange particles (, Λ, ) have been measured. Decays of resonances and heavy hyperons with an identified or Λ in the final state have been analyzed. Clear signals corresponding to and Σ(1385)^± have been observed. First results on the measurements of the Λ polarization in neutral current interactions have been obtained.     

Results on hyperon production from the NA57 experiment

Recent results on hyperon production in Pb-Pb collisions from the NA57 experiment are reported. Strangeness enhancements and the transverse mass spectra properties at 158 GeV per nucleon are described.     

Final results from the ντ appearance search in the NOMAD experiment

An updated analysis of the full NOMAD data corresponding to 1.35 × 10⁶ charged current interactions has been performed to search for neutrino oscillations through ν_τ appearance. This document updates the recently published results on the ν_μ → ν_τ and ν_μ → ν_e oscillations search in NOMAD [1] with a unified analysis of the hadronic channels.     

A study of quasielastic neutrino interactions ν μ n → μ− p in the NOMAD experiment

In this note, we present preliminary results on the study of the quasielastic reaction ν _μ n → μ⁻ p using the full set of NOMAD neutrino data. We perform a measurement of the total cross section of this process, normalizing to deep-inelastic scattering events selected from the same data sample. The measured cross section is found to be about 20% smaller than the world average of previous bubble chamber experiments. The analysis is still in progress since it is important to estimate the systematic uncertainties. for the NOMAD Collaboration The text was submitted by the authors in English.     

Results of the whole GALLEX experiment

After 5.5 years of data taking, GALLEX ended its experimental phase. The solar neutrino production rate, 76.4 ± 8 SNU, represents about 55% of the predicted rate. The As tests prove, at the 1% level, the reliability of the technique and the detection of ⁵¹Cr neutrino, with the nominal efficiency (93.0±8%), control the response of the detector to neutrinos in the solar energy range.     

Results from the UA 2 experiment at the CERN p¯p Collider

This paper presents results on the production and decay properties of the Intermediate Vector Bosons (IVB)W and Z⁰ and on the search of the top quark in the upgraded UA 2 detector at the CERNp¯p Collider. The analysed data have been taken in the 1988 and 1989 Collider running periods at the centre of mass energy of 630 GeV, and correspond to an integrated luminosity of 7·4 pb^–1.     

Results of the Bielefeld-Brookhaven e+-H experiment

Positronium formation (Ps) cross sections for positrons impinging on atomic hydrogen were measured in the impact energy range from 13 to 255 eV at the High Intensity Positron (HIP) beam at Brookhaven National Laboratory (BNL). The Ps-formation cross section was found to rise rapidly from the threshold at 6.8 eV to a maximum value of (2.98±0.18) ×10^–16 cm² for 15 eV positrons. By 75 eV it drops below the detection limit of 0.17×10^–16 cm² which is the present level of statistical uncertainty. A more elaborate data analysis was performed leading to somewhat smaller cross sections than originally published [1]. During the course of this experiment further relative data on impact-ionization cross sections were accumulated.     

CMS experiment at the LHC: Results and outlook

The results of the CMS experiment based on the LHC first-run data taken at c.m.s. energies of 7 and 8 TeV and on the first data taken in the second-run at the c.m.s. energy of 13 TeV are presented. The research prospects with the LHC running at high luminosity are discussed.