Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

The Impact of Fast-Rise-Time Electromagnetic Field and Pressure on the Aggregation of Peroxidase upon Its Adsorption onto Mica

Our present study concerns the influence of the picosecond rise-time-pulsed electromagnetic field, and the impact of nanosecond pulsed pressure on the aggregation state of horseradish peroxidase (HRP) as a model enzyme. The influence of a 640 kV/m pulsed electromagnetic field with a pulse rise-time of ~200 ps on the activity and aggregation state of an enzyme is studied by the single-molecule atomic force microscopy (AFM) method. The influence of such a field is shown to lead to aggregation of the protein and to a decrease in its enzymatic activity. Moreover, the effect of a shock wave with a pressure front rise-time of 80 ns on the increase in the HRP aggregation is demonstrated. The results obtained herein can be of use in modeling the impact of electromagnetic and pressure pulses on enzymes and on whole living organisms. Our results are also important for taking into account the effect of pulsed fields on the body in the development of drugs, therapeutic procedures, and novel highly sensitive medical diagnosticums

Measurement of charged particle spectra in minimum-bias events from proton-proton collisions at root s =13 TeV

Pseudorapidity, transverse momentum, and multiplicity distributions are measured in the pseudorapidity range vertical bar eta vertical bar 0.5 GeV in proton-proton collisions at a center-of-mass energy of root s = 13 TeV. Measurements are presented in three different event categories. The most inclusive of the categories corresponds to an inelastic pp data set, while the other two categories are exclusive subsets of the inelastic sample that are either enhanced or depleted in single diffractive dissociation events. The measurements are compared to predictions from Monte Carlo event generators used to describe high-energy hadronic interactions in collider and cosmic-ray physics.Peer reviewe

Study of the normalized transverse momentum distribution of WW bosons produced in ppˉp \bar p collisions at s\sqrt {s} = 1.96 TeV

International audienceWe present a study of the normalized transverse momentum distribution of W bosons produced in pp¯ collisions, using data corresponding to an integrated luminosity of 4.35  fb-1 collected with the D0 detector at the Fermilab Tevatron collider at s=1.96  TeV. The measurement focuses on the transverse momentum region below 15 GeV, which is of special interest for electroweak precision measurements; it relies on the same detector calibration methods which were used for the precision measurement of the W boson mass. The measured distribution is compared to different QCD predictions and a procedure is given to allow the comparison of any further theoretical models to the D0 data

Evidence for Zc±(3900)Z_c^{\pm}(3900) in semi-inclusive decays of bb-flavored hadrons

International audienceWe present evidence for the exotic charged charmoniumlike state Zc±(3900) decaying to J/ψπ± in semi-inclusive weak decays of b-flavored hadrons. The signal is correlated with a parent J/ψπ+π- system in the invariant-mass range 4.2–4.7 GeV that would include the exotic structure Y(4260). The study is based on 10.4  fb−1 of pp¯ collision data collected by the D0 experiment at the Fermilab Tevatron collider

Inclusive production of the PcP_c resonances in pp‾p \overline p collisions

We present a study of the inclusive production in $p \overline p$ collisions of the pentaquark states $P_c(4440)$ and $P_c(4457)$ with the decay to the $J/\psi p$ final state previously observed by the LHCb experiment. Using a sample of candidates originating from decays of $b$-flavored hadrons, we find an enhancement in the $J/\psi p$ invariant mass distribution consistent with a sum of $P_c(4440)$ and $P_c(4457)$. The significance, with the input parameters set to the LHCb values, is $3.0\sigma$. This is the first confirmatory evidence for these pentaquark states. We measure the ratio $N_{\rm prompt}/N_{\rm nonprompt}=0.05 \pm 0.39$ and set an upper limit of 0.8 at the 95\% credibility level. The ratio of the yield of the $P_c(4312)$ to the sum of $P_c(4440)$ and $P_c(4457)$ is less than 0.6 at the 95\% credibility level. The study is based on $10.4~\rm{fb^{-1}}$ of data collected by the D0 experiment at the Fermilab Tevatron collider

Studies of X(3872)X(3872) and ψ(2S)\psi(2S) production in ppˉp\bar{p} collisions at 1.96 TeV

International audienceWe present various properties of the production of the X(3872) and ψ(2S) states based on 10.4  fb-1 collected by the D0 experiment in Tevatron pp¯ collisions at s=1.96  TeV. For both states, we measure the nonprompt fraction fNP of the inclusive production rate due to decays of b-flavored hadrons. We find the fNP values systematically below those obtained at the LHC. The fNP fraction for ψ(2S) increases with transverse momentum, whereas for the X(3872) it is constant within large uncertainties, in agreement with the LHC results. The ratio of prompt to nonprompt ψ(2S) production, (1-fNP)/fNP, decreases only slightly going from the Tevatron to the LHC, but for the X(3872), this ratio decreases by a factor of about 3. We test the soft-pion signature of the X(3872) modeled as a weakly bound charm-meson pair by studying the production of the X(3872) as a function of the kinetic energy of the X(3872) and the pion in the X(3872)π center-of-mass frame. For a subsample consistent with prompt production, the results are incompatible with a strong enhancement in the production of the X(3872) at the small kinetic energy of the X(3872) and the π in the X(3872)π center-of-mass frame expected for the X+soft-pion production mechanism. For events consistent with being due to decays of b hadrons, there is no significant evidence for the soft-pion effect, but its presence at the level expected for the binding energy of 0.17 MeV and the momentum scale Λ=M(π) is not ruled out