Evidence for a ... State Abazov, V M; Abbott, B; Acharya, B S ...
Physical review letters,
07/2016, Letnik:
117, Številka:
2
Journal Article
Recenzirano
(ProQuest: ... denotes formulae and/or non-USASCII text omitted)We report evidence for a narrow structure, X(5568), in the decay sequence ... This is evidence for the first instance of a hadronic ...state with valence quarks of four different flavors. The mass and natural width of this state are measured to be ... and ... If the decay is ... with an unseen gamma, m(X(5568)) will be shifted up by ... This measurement is based on 10.4fb super(?1) of pp collision data at radicals =1.96TeV collected by the D0 experiment at the Fermilab Tevatron collider.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted) The lifetime of the ... meson is measured in the decay channel ... with 880< or =M sub(pi+pi?)< or =1080MeV/c sub(2), which is mainly ...a CP-odd state and dominated by the f sub(0)(980) resonance. In 10.4fb super(?1) of data collected with the D0 detector in Run II of the Tevatron, the lifetime of the ... meson is measured to be tau(...)=1.70+ or -0.14(stat)+ or -0.05(syst)ps. Neglecting CP violation in ... mixing, the measurement can be translated into the width of the heavy mass eigenstate of the ... (stat)+ or -0.02(syst)ps super(?1).
We report evidence for the simultaneous production of J/psi and Upsilon mesons in 8.1fb super(-1) of data collected at radicals=1.96TeV by the D0 experiment at the Fermilab pp Tevatron Collider. ...Events with these characteristics are expected to be produced predominantly by gluon-gluon interactions. In this analysis, we extract the effective cross section characterizing the initial parton spatial distribution, sigma sub(eff)=2.2+ or -0.7(stat)+ or -0.9(syst)mb.
We study Lambda and Lambda production asymmetries in pp arrow right Lambda(Lambda)X , pp arrow right J/psiLambda(Lambda)X, and pp arrow right mu super(+ or -)Lambda(Lambda)X events recorded by the D0 ...detector at the Fermilab Tevatron collider at radicals=1.96TeV . We find an excess of Lambda's (Lambda's) produced in the proton (antiproton) direction. This forward-backward asymmetry is measured as a function of rapidity. We confirm that the Lambda/Lambda production ratio, measured by several experiments with various targets and a wide range of energies, is a universal function of "rapidity loss," i.e., the rapidity difference of the beam proton and the lambda.
NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for the R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility for Antiproton and Ion ...Research). NeuLAND detects neutrons with energies from 100 to 1000 MeV, featuring a high detection efficiency, a high spatial and time resolution, and a large multi-neutron reconstruction efficiency. This is achieved by a highly granular design of organic scintillators: 3000 individual submodules with a size of 5 × 5 × 250 cm3 are arranged in 30 double planes with 100 submodules each, providing an active area of 250 × 250 cm2 and a total depth of 3 m. The spatial resolution due to the granularity together with a time resolution of σt≤ 150 ps ensures high-resolution capabilities. In conjunction with calorimetric properties, a multi-neutron reconstruction efficiency of 50% to 70% for four-neutron events will be achieved, depending on both the emission scenario and the boundary conditions allowed for the reconstruction method. We present in this paper the final design of the detector as well as results from test measurements and simulations on which this design is based.
We observe a signal for the doubly charmed baryon Xi(+)(cc) in the charged decay mode Xi(+)(cc)-->Lambda(+)(c)K-pi(+) in data from SELEX, the charm hadroproduction experiment at Fermilab. We observe ...an excess of 15.9 events over an expected background of 6.1+/-0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is 3519+/-1 MeV/c(2). The Gaussian mass width of this state is 3 MeV/c(2), consistent with resolution; its lifetime is less than 33 fs at 90% confidence.
The absolute differential cross sections for small-angle proton elastic scattering off the nuclei \(^{12,14-17}\)C have been measured in inverse kinematics at energies near 700 MeV/u at GSI ...Darmstadt. The hydrogen-filled ionization chamber IKAR served simultaneously as a gas target and a detector for the recoil protons. The projectile scattering angles were measured with multi-wire tracking detectors. The radial nuclear matter density distributions and the root-mean-square nuclear matter radii were deduced from the measured cross sections using the Glauber multiple-scattering theory. A possible neutron halo structure in \(^{15}\)C, \(^{16}\)C and \(^{17}\)C is discussed. The obtained data show evidence for a halo structure in the \(^{15}\)C nucleus.
In order to study the spatial structure of exotic nuclei, it was proposed at the Petersburg Nuclear Physics Institute (PNPI) to measure the differential cross section for small-angle proton elastic ...scattering in inverse kinematics. Several experiments in beams of 0.7-GeV/nucleon exotic nuclei were performed at the heavy-ion accelerator facility of GSI (Gesellschaft für Schwerionenforschung, Darmstadt, Germany) by using the IKAR ionization spectrometer developed at PNPI. The IKAR ionization chamber filled with hydrogen at a pressure of 10 bar served simultaneously as a target and as a recoil-proton detector, which measured the recoil-proton energy. The beam-particle scattering angle was also measured. The results obtained for the cross sections in question were analyzed on the basis of the Glauber-Sitenko theory using phenomenological nuclear-density distributions with two free parameters. Nuclear-matter distributions and root-mean-square radii were found for the nuclei under investigation. The size of the halo in the
6
He,
8
He,
11
Li, and
14
Be nuclei was determined among other things. Information about neutron distributions in nuclei was deduced by combining the data obtained here with the known values of the radii of proton distributions. A sizable neutron skin was revealed in the
8
Li,
9
Li, and
12
Be nuclei.
A search for the rare two-body charmless baryonic decay $B^+ \to p \bar\Lambda$ is performed with $pp$ collision data, corresponding to an integrated luminosity of $3\mbox{\,fb}^{-1}$, collected by ...the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. An excess of $B^+ \to p \bar\Lambda$ candidates with respect to background expectations is seen with a statistical significance of 4.1 standard deviations, and constitutes the first evidence for this decay. The branching fraction, measured using the $B^+ \to K^0_{\mathrm S} \pi^+$ decay for normalisation, is \begin{eqnarray} \mathcal{B}(B^+ \to p \bar\Lambda) & = & ( 2.4 \,^{+1.0}_{-0.8} \pm 0.3 ) \times 10^{-7} \,, \nonumber \end{eqnarray} where the first uncertainty is statistical and the second systematic.
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