A. Karev

Limits on neutral light scalar and pseudoscalar particles in a proton beam dump experiment

A search has been performed for weakly interacting neutral light scalar and pseudoscalar particles in a proton beam dump experiment. No positive signal is observed. Limits on the mass and life-time of these particles are set in the frame of the Standard Model and its minimal supersymmetric extension. The Higgs particle of theSU2L×U1 Standard Theory is excluded for masses in the range 1 MeV<mH<80 MeV at 95%CL. Limits on the Peccei-Quinn like axions are derived.

LIMITS ON THE MASS OF LIGHT (PSEUDO)SCALAR PARTICLES FROM BETHE-HEITLER e+e− and μ+μ− PAIR PRODUCTION IN A PROTON-IRON BEAM DUMP EXPERIMENT

A search has been performed for weakly interacting neutral light scalar and pseudoscalar particles in a proton-iron beam dump experiment via the Bethe-Heitler process. No positive signal was observed. Limits are derived on the masses of these particles in the framework of the Standard Model and its minimal supersymmetric extension (MSSM) comparing the experimental results with expectations for Bethe-Heitler e+e− and μ+μ− pair production. The Higgs particle of the SU2L×U1 Standard Theory is excluded for masses in the range mH<0.9 MeV at 95% CL. Limits on light Higgs particles of the MSSM and Peccei-Quinn like axions are derived.

The IHEP-JINR neutrino detector at neutrino beams of the U-70 accelerator (Protvino)

The design and parameters of the IHEP–JINR neutrino detector, the largest experimental setup at the U-70 accelerator (IHEP, Protvino), is described. The main detector components (the drift chambers, the liquid-scintillator counters, the detector of electromagnetic showers, and the magnetic system) are described in detail. The organization of the on-line data-acquisition system and the off-line software is outlined. The main characteristics of the detector are presented. The basic physical results obtained with the setup are briefly described.

Investigation of prompt electron-neutrino production in a proton beam dump experiment with the IHEP-JINR ν detector

Abstract The production of prompt and ordinary ( ν ) e was investigated in a proton beam dump experiment at the 70 GeV Serpukhov accelerator measuring their interactions in the IHEP-JINR neutrino detector. An upper limit of σ charm μ b/nucleon at 90% CL was obtained near the production threshold.

Mass limits on a light Higgs boson from π-, K-, η′ -meson decays in the 70 GeV proton beam-dump experiment

Abstract Data from a 70 GeV proton-iron beam-dump experiment and the theoretical predictions of light Higgs production from the decays π ± →e ± V (∼) e H, K ± →e ± V (∼) e H, K ± →π ± H, K 0 L →π 0 H, η′→η′H were used to establish limits on the mass of a scalar Higgs boson in the context of the standard model. The mass range 1 m H c 2 was excluded at 95% CL.

Strangeness from 20-A-GeV to 158-A-GeV

New results from the energy scan programme of NA49, in particular kaon production at 30 A GeV and Φ production at 40 and 80 A GeV are presented. The K + /π + ratio shows a pronounced maximum at 30 A GeV; the kaon slope parameters are constant at SPS energies. Both findings support the scenario of a phase transition at about 30 A GeV beam energy. The Φ/π ratio increases smoothly with beam energy, showing an energy dependence similar to K - /π - . The measured particle yields can be reproduced by a hadron gas model, with chemical freeze-out parameters on a smooth curve in the T-μ B plane. The transverse spectra can be understood as resulting from a rapidly expanding, locally equilibrated source. No evidence for an earlier kinetic decoupling of heavy hyperons is found.