New program for computation of the thermodynamic, spectral, and NMR relaxation parameters of coordination compounds in complex systems

A new approach providing a direct calculations of equilibrium constants, parameters of the chemical exchange reactions, and spectral characteristics of complexes on the basis of data of several methods including pH-potentiometry, multi-wavelength electronic spectroscopy, and NMR relaxation within a single computer program was proposed and realized in the program STALABS. Application of the STALABS program has been demonstrated on the example of investigation of the complex nickel(II) - L-histidine system by joint usage of the above three methods

Thermally Isolated Ruthenium Nanobolometer for Room-Temperature Operation

We propose a bolometer intended for room-temperature operation and based on a 100-nm-wide ruthenium (Ru) strip fabricated on a thin layer of cross-linked polymethyl methacrylate (XPMMA). This layer provides thermal isolation between the silicon substrate and the Ru nanostrip for increasing the nonlinearity of the bolometer I- V curve due to more intensive self-heatingby the biasing and an ac current. A number of bolometers with Ru strips of different dimensions and different thicknesses of XPMMA layer were fabricated and tested at dc. An estimate based on the dc tests gives the electrical voltage responsivity to radio frequency (RF) signal as much as 250 V/W, which makes the proposed bolometer attractive as a sensing element for a simple and low-cost microwave and terahertz detector. Numerical simulations of temperature distribution along the Ru strip and analysis of the bolometer noise performance are also presented

Study of the lineshape of the χc1(3872)\chi_{c1}(3872) state

A study of the lineshape of the $\chi_{c1}(3872)$ state is made using a data sample corresponding to an integrated luminosity of 3 fb$^{-1}$ collected in pp collisions at center-of-mass energies of 7 and 8 TeV with the LHCb detector. Candidate $\chi_{c1}(3872)$ and $ψ(2S)$ mesons from $b$-hadron decays are selected in the $J/ψπ^+π^-$ decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the $\chi_{c1}(3872)$) and $ψ(2S)$ states, $Δm$, and the width of the $\chi_{c1}(3872)$ state, $Γ_{BW}$, are determined to be $\frac {Δm=185.598±0.067±0.068 \, MeV,} {Γ_{BW}=1.39±0.24±0.10 \, MeV}$, where the first uncertainty is statistical and the second systematic. Using a Flatté-inspired model, the mode and full width at half maximum of the lineshape are determined to be $\frac {mode=3871.69_{-0.04-0.13}^{+0.00+0.05} MeV,} {FWHM=0.22_{-0.06-0.13}^{+0.07+0.11} MeV}$. An investigation of the analytic structure of the Flatté amplitude reveals a pole structure, which is compatible with a quasibound $D^0\bar{D}^{*0}$ state but a quasivirtual state is still allowed at the level of 2 standard deviations

Observation of a new Ξb0\Xi_b^0 state

International audienceUsing a proton-proton collision data sample collected by the LHCb experiment, corresponding to an integrated luminosity of 8.5  fb-1, the observation of a new excited Ξb0 resonance decaying to the Ξb-π+ final state is presented. The state, referred to as Ξb(6227)0, has a measured mass and natural width of m(Ξb(6227)0)=6227.1-1.5+1.4±0.5  MeV and Γ(Ξb(6227)0)=18.6-4.1+5.0±1.4  MeV, where the uncertainties are statistical and systematic. The production rate of the Ξb(6227)0 state relative to that of the Ξb- baryon in the kinematic region 2<η<5 and pT<30  GeV is measured to be fΞb(6227)0fΞb-B(Ξb(6227)0→Ξb-π+)=0.045±0.008±0.004, where B(Ξb(6227)0→Ξb-π+) is the branching fraction of the decay, and fΞb(6227)0 and fΞb- represent fragmentation fractions. Improved measurements of the mass and natural width of the previously observed Ξb(6227)- state, along with the mass of the Ξb- baryon, are also reported. Both measurements are significantly more precise than, and consistent with, previously reported values

Search for long-lived particles decaying to e±μ∓νe^\pm \mu^\mp \nu

Long-lived particles decaying to ${e ^\pm } {\mu ^\mp } {\nu }$, with masses between 7 and $50 \,\text {GeV/}c^2$ and lifetimes between 2 and $50 \,\text {ps}$, are searched for by looking at displaced vertices containing electrons and muons of opposite charges. The search is performed using $5.4 \,\text {fb} ^{-1}$ of $p p$ collisions collected with the LHCb detector at a centre-of-mass energy of $\sqrt{s} = 13 \,\text {TeV}$. Three mechanisms of production of long-lived particles are considered: the direct pair production from quark interactions, the pair production from the decay of a Standard-Model-like Higgs boson with a mass of $125 \,\text {GeV/}c^2$, and the charged current production from an on-shell $W$ boson with an additional lepton. No evidence of these long-lived states is obtained and upper limits on the production cross-section times branching fraction are set on the different production modes

Search for long-lived particles decaying to e±μ∓νe^\pm \mu^\mp \nu

International audienceLong-lived particles decaying to ${e ^\pm } {\mu ^\mp } {\nu }$, with masses between 7 and $50 \,\text {GeV/}c^2$ and lifetimes between 2 and $50 \,\text {ps}$, are searched for by looking at displaced vertices containing electrons and muons of opposite charges. The search is performed using $5.4 \,\text {fb} ^{-1}$ of $p p$ collisions collected with the LHCb detector at a centre-of-mass energy of $\sqrt{s} = 13 \,\text {TeV}$. Three mechanisms of production of long-lived particles are considered: the direct pair production from quark interactions, the pair production from the decay of a Standard-Model-like Higgs boson with a mass of $125 \,\text {GeV/}c^2$, and the charged current production from an on-shell $W$ boson with an additional lepton. No evidence of these long-lived states is obtained and upper limits on the production cross-section times branching fraction are set on the different production modes