The silicon tracking system of the BM@N experiment consists of four stations based on double-sided microstrip silicon sensors. The sensors make it possible to obtain a spatial resolution for tracks of secondary charged particles up to 17 μm. Two ASIC boards, the input channels of which are connected to the strips with ultralight (0.23% X 0 ) aluminum flex cables, are used to readout and process signals from both sides of the sensor. Such an assembly is called a module. Silicon sensors are mounted on lightweight carbon-fiber support trusses in a way that the dead zones at the edges are overlapped due to the tiled layout. The frontend electronics are housed in metal containers with a heat sink system located at the rare ends of the carbon-fiber support truss. A set of modules attached to the carbon-fiber support truss with two containers with readout electronics at the ends is called a supermodule. The accuracy of the sensor positioning in the station plane plays a crucial role in limiting the degrees of freedom of the parameters determined by the software during the final alignment of the tracking system elements. A special device that allows mounting sensors on a carbon fiber truss with an accuracy of up to 15 µm on a 1200 mm base is developed to assemble supermodules. The results of testing the device are given.

The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (√sNN = 2-4.9 GeV) is to discover fundamental properties of QCD matter, namely, the equation-of-state at high density as it is expected to occur in the core of neutron stars, effects of chiral symmetry, and the phase structure at large baryon-chemical potentials (μB ≥ 500 MeV).We are focusing here on the contribution of JINR to the CBM experiment: design of the superconducting dipole magnet; manufacture of the straw and micro-strip silicon detectors, participation in the data taking and analysis algorithms and physics program.

A search for the rare decays B 0 s → π + π − μ + μ − and B 0 → π + π − μ + μ − is performed in a data set corresponding to an integrated luminosity of 3 . 0 fb − 1 collected by the LHCb detector in proton– proton collisions at centre-of-mass energies of 7 and 8 TeV. Decay candidates with pion pairs that have invariant mass in the range 0 . 5–1 . 3 GeV / c 2 and with muon pairs that do not originate from a resonance are considered. The first observation of the decay B 0 s → π + π − μ + μ − and the first evidence of the decay B 0 → π + π − μ + μ − are obtained and the branching fractions, restricted to the dipion-mass range considered, are measured to be B ( B 0 s → π + π − μ + μ − ) = ( 8 . 6 ± 1 . 5 ( stat ) ± 0 . 7 ( syst ) ± 0 . 7 ( norm )) × 10 − 8 and B ( B 0 → π + π − μ + μ − ) = ( 2 . 11 ± 0 . 51 ( stat ) ± 0 . 15 ( syst ) ± 0 . 16 ( norm )) × 10 − 8 , where the third uncertainty is due to the branching fraction of the decay B 0 → J /ψ( → μ + μ − ) K ∗ ( 892 ) 0 ( → K + π − ) , used as a normalisation. © 2015 The Authors. Published by Elsevier B.V. This an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP 3 .