Search results for "38"
showing 10 items of 1730 documents
Charmonium description from a generalized screened potential model
2015
A generalized screened potential model (GSPM), recently developed to study the bottomonium spectrum, is applied to the calculation of charmonium masses and electromagnetic widths. The presence in the GSPM of more quark-antiquark bound states than in conventional non screened potential models, allows for the assignment of GSPM states to cataloged non conventional $J^{++}$ charmonium resonances as well as for the prediction of new (non cataloged) $J^{++}$ states. The results obtained seem to indicate that a reasonable overall description of $J^{++}$ charmonium resonances is feasible.
Search forB+→X(3872)K+,X(3872)→J/ψγ
2006
In a study of B+ --> J/psi gamma K+ decays, we find evidence for the radiative decay X(3872) --> J/psi gamma with a statistical significance of 3.4 sigma. We measure the product of branching fractions BF(B+ --> X(3872) K+).BF(X(3872) --> J/psi gamma) = (3.3 +/- 1.0 +/- 0.3) x 10^-6, where the uncertainties are statistical and systematic, respectively. We also measure the branching fraction BF(B+ --> chi_c1 K+) = (4.9 +/- 0.2 +/- 0.4) x 10^-4. These results are obtained from (287+/-3) million BBar decays collected at the Y(4S) resonance with the BaBar detector at the PEP-II B Factory at SLAC.
Nuclear structure “southeast” ofPb208: Isomeric states inHg208andTl209
2009
The nuclear structure of neutron-rich N>126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A=1 GeV U-238 beam. Metastable states in the N=128 isotones Hg-208 and Tl-209 have been identified. Delayed gamma-ray transitions are interpreted as arising from the decay of I-pi=(8(+)) and (17/2(+)) isomers, respectively. The data allow for the so far most comprehensive verification of the shell-model approach in the region determined by magic numbers Z 126.
Production of neutron-rich isotopes in fission of uranium induced by neutrons of 20 MeV average energy
2000
In the context of a parameter study conducted by several laboratories for future European radioactive beam facilities based on fast-neutron induced fission, in particular for the SPIRAL-II project at GANIL, we have measured the yields of neutron-rich isotopes in the mass range of 88 to 144. These nuclei were obtained as fission products of natural uranium bombarded by neutrons of 20 MeV average energy emitted by a thick carbon target irradiated by 50 MeV deuterons. Yields have been measured using on-line mass separation with the ion-guide method. Compared with proton-induced fission at 25 MeV the magnitude of cross-sections, except for the symmetric region, is similar. Z-distributions of is…
Production of neutron-rich nuclei in fission induced by neutrons generated by the p + 13C reaction at 55 MeV
2003
Cross-sections for the production of neutron-rich nuclei obtained by neutron-induced fission of natural uranium have been measured. The neutrons were generated by bombarding a 13C target with 55 MeV protons. The results, position of the maximum in the (Z, A)-plane, width and magnitude, are very comparable with those where the neutrons are generated by bombardment of natural 12C graphite with 50 MeV deuterons. Depending on the geometry of the converter/target assembly the isotope yields, however, are a factor of 2-3 lower due to less efficient production of neutrons per primary projectile, especially at small forward angles.
Evidence for the decay X(3872)→ψ(2S)γ
2014
Evidence for the decay mode X(3872) -> psi(2S)gamma in B+ -> X(3872)K+ decays is found with a significance of 4.4 standard deviations. The analysis is based on a data sample of proton proton collisions, corresponding to an integrated luminosity of 3 fb(-1), collected with the LHCb detector, at centre-of-mass energies of 7 and 8 TeV. The ratio of the branching fraction of the X(3872) -> psi(2S)gamma decay to that of the X(3872) -> J/psi gamma decay is measured to be B(X(3872) -> psi(2S)gamma)/B(X(3872) -> J/psi gamma) = 2.46 +/- 0.64 +/- 0.29, where the first uncertainty is statistical and the second is systematic. The measured value does not support a pure D (D) over bar* molecular interpre…
Search for muoproduction of X(3872) at COMPASS and indication of a new state X˜(3872)
2018
Abstract We have searched for exclusive production of exotic charmonia in the reaction μ + N → μ + ( J / ψ π + π − ) π ± N ′ using COMPASS data collected with incoming muons of 160 GeV/c and 200 GeV/c momentum. In the J / ψ π + π − mass distribution we observe a signal with a statistical significance of 4.1 σ. Its mass and width are consistent with those of the X ( 3872 ) . The shape of the π + π − mass distribution from the observed decay into J / ψ π + π − shows disagreement with previous observations for X ( 3872 ) . The observed signal may be interpreted as a possible evidence of a new charmonium state. It could be associated with a neutral partner of X ( 3872 ) with C = − 1 predicted b…
ON THE NATURE OF THE X(3872)
2010
We present recent studies of charmonium multiquark states. We use different interacting models and numerical methods to study deeply bound four-quark states and meson-meson molecules. No deeply bound four-quark states are found in our analysis. A nice description of the X(3872) is obtained as a $D\bar{D}^*-J/\Psi\omega$ coupled channel state.
Search for a charged partner of theX(3872)in theBmeson decayB→X−K,X−→J/ψπ−π0
2005
We search for a charged partner of the X(3872) in the decay B --> X- K, X- --> J/psi pi- pi0, using 234 million BBbar events collected at the Y(4S) resonance with the BaBar detector at the PEP-II e+e- asymmetric-energy storage ring. The resulting product branching fraction upper limits are BR(B0 --> X- K+, X- --> J/psi pi- pi0) X- K0bar,X- --> J/psi pi- pi0) < 22 x 10(-6) at the 90% confidence level.
Open charm hadroproduction and the charm content of the proton
2009
We advocate charmed-hadron inclusive hadroproduction as a laboratory to probe intrinsic charm (IC) inside the colliding hadrons. Working at next-to-leading order in the general-mass variable-flavor-number scheme endowed with non-perturbative fragmentation functions recently extracted from a global fit to e^+e^- annihilation data from KEKB, CESR, and LEP1, we first assess the sensitivity of Tevatron data of D^0, D^+, and D^{*+} inclusive production to the IC parameterizations provided by Pumplin et al. We then argue that similar data from pp collisions at RHIC would have the potential to discriminate between different IC models provided they reach out to sufficiently large values of transver…