119395992
Dilepton production from p-p to CaCa at the Bevalac
Abstract The DLS collaboration has recently completed a high statistics study of dilepton production at the Bevalac. In particular, we have measured dielectrons (e + e − ) from p - p and p - d collisions to understand the basic dilepton production mechanisms in the energy range from 1.05 – 4.9 GeV. These data can be used to determine the basic processes which contribute to nucleon-nucleon dilepton production such as hadronic bremsstrahlung, vector meson processes, and hadronic Dalitz decay. The data show that a simple elastic bremsstrahlung calculation is insufficient to explain the data. Theoretical models are compared with the data. A new high statistics study of Ca  Ca at 1.05 A·GeV has been made to study the collectivity of A - A collisions.
44598663
Measurement of dielectron production in niobium-niobium collisions at 1.05 GeV/nucleon.
A dielectron signal for pair masses greater than [ital M][sub [pi]] is observed in Nb+Nb collisions at 1.05 GeV/nucleon beam kinetic energy. The invariant mass spectrum and the associated multiplicity distribution are presented. Comparisons are made with previous cross section measurements in [ital p]+Be and Ca+Ca.
6986761
Threshold behavior of electron pair production in p-Be collisions.
We report on the measurements of electron pair production in /ital p/-Becollisions at 1.0, 2.1, and 4.9 GeV beam kinetic energies. The invariant-massand transverse-momentum spectra are presented, along with the total crosssections. A rapid decrease in the integrated cross section is observed as thebeam energy is reduced. Comparison of the excitation function for dielectron(/ital e//sup +/e/sup /minus//) and dipion (..pi../sup +/..pi../sup /minus//)production suggests that the dominant production mechanism at beam kineticenergies 2.1 and 4.9 GeV may be ..pi../sup +/..pi../sup /minus// annihilation.
33345865
Mass and transverse momentum dependence of dielectron production in p+d and p+p collisions at 4.9 GeV.
Dielectron production in [ital p]+[ital d] and [ital p]+[ital p] collisions at the beam kinetic energy of 4.9 GeV has been measured with the Dilepton Spectrometer. Features of the dielectron cross section have been studied with cuts on the mass and transverse momentum of the pairs. The spectra for several regions of phase space are presented as a function of the pair mass and transverse momentum.
118600395
Analysis of strong decays of the charmed mesons D(2550), D(2600), D(2750) and D(2760)
In this article, we study the strong decays of the newly observed charmed mesons D(2550), D(2600), D(2750), and D(2760) with the heavy quark effective theory in the leading order approximation, and tentatively identify the (D(2550),D(2600)) as the 2S doublet (0{sup -},1{sup -}) and the (D(2750),D(2760)) as the 1D doublet (2{sup -},3{sup -}), respectively. The identification of the D(2750) and D(2760) as the same particle with J{sup P}=3{sup -} is disfavored.
119241580
Analysis of the scalar and axial-vector heavy diquark states with QCD sum rules
In this article, we study the mass spectrum of the scalar and axial-vector heavy diquark states with the QCD sum rules in a systematic way. Once the reasonable values are obtained, we can take them as basic parameters and study the new charmonium-like states as the tetraquark states.
119548246
Subarcsecond Resolution Mid-Infrared Observations of Super Star Clusters in the Antennae (NGC 4038/4039)*
We present ground-based subarcsecond mid-infrared imaging and spectroscopy of young super star clusters in the overlap region of the merging galaxies NGC 4038/4039 (the Antennae) obtained with the VLT Imager and Spectrometer for mid-InfraRed (VISIR). With its unprecedented spatial resolution, VISIR begins for the first time to resolve the H II/photodissociation region complexes around the star-forming regions. In the N-band spectra of two young star clusters, unexpectedly low polycyclic aromatic hydrocarbon (PAH) emission is observed, compared to what is seen with the Infrared Space Observatory and with the Spitzer Space Telescope. We conclude that a large fraction of the PAH emission cannot be directly associated with the super star clusters but originates from an extended region of at least 215 pc radius around the clusters. In the distribution of [Ne II] 12.81 μm emission, a highly obscured cluster is discovered that does not have an optical or near-infrared counterpart.
125952499
Representations of the loop braid group
124130898
Study of the neutron-rich nucleus Si-36
Excited states of N=22 Si-36, populated in deep-inelastic processes produced by the interaction of a 215 MeV beam of S-36 ions with a Pb-208 target, were studied in the present work. gamma rays from the binary fragments detected using CLARA, an array of 25 Ge Clover detectors, were measured in coincidence with projectile-like fragments detected by PRISMA, a large solid angle magnetic spectrometer. Two new gamma-ray photopeaks at energies of 1442 and 842 keV were observed and tentatively assigned to the 4(+)-> 2(+) and 6(+)-> 4(+) transitions, respectively. The systematics of the level structures of N=22 isotones are presented, and a comparison is made of the behavior of Si, Mg, and S isotopes. The level structure of Si-36 is also compared with the results of sdpf shell model calculations.