Search for Exotic Mesons in pi- P Interactions at 18 GeV/c

The recent search for non $q \bar{q}$ mesons in $\pi^{-}p$ interactions at Brookhaven National Laboratory is summarized. Many final states such as $\eta \pi$, $\eta' \pi^{-}$, $a_{0} \pi$, $f_{1} \pi$, $a_{2} \pi$, $b_{1} \pi$, which are favored decay modes of exotics, are under investigation.Comment: 9 pages, PostScript, Presented at the International School of Nuclear Physics, Erice, Sicily, Italy, September 199

Observation of a New J(PC)=1(+-) Isoscalar State in the Reaction Pi- Proton -> Omega Eta Neutron at 18 GeV/c

Results are presented on a partial wave analysis of the Omega Eta final state produced in Pi- Proton interactions at 18 GeVc where Omega -> Pi+ Pi- Pi0, Pi0 -> 2 Gammas, and Eta -> 2 Gammas. We observe the previously unreported decay mode Omega(1650) -> Omega Eta and a new 1(+-) meson state h1(1595) with a mass M=1594(15)(+10)(-60) MeV/c^2 and a width Gamma=384(60)(+70)(-100) MeV/c^2. The h1(1595) state exhibits resonant-like phase motion relative to the Omega(1650).Comment: Submitted to Physics Letters B Eight total pages including 11 figures and 1 tabl

Chiral Symmetry Amplitudes in the S-Wave Isoscalar and Isovector Channels and the \sigma, f_0(980), a_0(980) Scalar Mesons

We use a nonperturbative approach which combines coupled channel Lippmann Schwinger equations with meson-meson potentials provided by the lowest order chiral Lagrangians. By means of one parameter, a cut off in the momentum of the loop integrals, which results of the order of 1 GeV, we obtain singularities in the S-wave amplitudes corresponding to the \sigma,f_0 and a_0 resonances. The \pi\pi-->\pi\pi, \pi\pi-->K\bar{K} phase shifts and inelasticities in the T=0 scalar channel are well reproduced as well as the \pi^-\eta and K^-K^0 mass distributions in the T=1 channel. Furthermore, the total and partial decay widths of the f_0 and a_0 resonances are properly reproduced including also the decay into the \gamma\gamma channel. The results seem to indicate that chiral symmetry constraints at low energy and unitarity in coupled channels is the basic information contained in the meson-meson interaction below \sqrt(s)=1.2 GeV.Comment: latex, 22 pages, 9 figure

Evidence for a narrow dip structure at 1.9 GeV/c2^2 in 3π+3π−3\pi^+ 3\pi^- diffractive photoproduction

A narrow dip structure has been observed at 1.9 GeV/c$^2$ in a study of diffractive photoproduction of the $~3\pi^+3\pi^-$ final state performed by the Fermilab experiment E687.Comment: The data of Figure 6 can be obtained by downloading the raw data file e687_6pi.txt. v5 (2nov2018): added Fig. 7, the 6 pion energy distribution as requested by a reade

Search for W' bosons decaying to an electron and a neutrino with the D0 detector

This Letter describes the search for a new heavy charged gauge boson W' decaying into an electron and a neutrino. The data were collected with the D0 detector at the Fermilab Tevatron proton-antiproton Collider at a center-of-mass energy of 1.96 TeV, and correspond to an integrated luminosity of about 1 inverse femtobarn. Lacking any significant excess in the data in comparison with known processes, an upper limit is set on the production cross section times branching fraction, and a W' boson with mass below 1.00 TeV can be excluded at the 95% C.L., assuming standard-model-like couplings to fermions. This result significantly improves upon previous limits, and is the most stringent to date.Comment: submitted to Phys. Rev. Let

Measurement of the ratios of the Z/G* + >= n jet production cross sections to the total inclusive Z/G* cross section in ppbar collisions at sqrt(s) = 1.96 TeV

We present a study of events with Z bosons and jets produced at the Fermilab Tevatron Collider in ppbar collisions at a center of mass energy of 1.96 TeV. The data sample consists of nearly 14,000 Z/G* -> e+e- candidates corresponding to the integrated luminosity of 0.4 fb-1 collected using the D0 detector. Ratios of the Z/G* + >= n jet cross sections to the total inclusive Z/G* cross section have been measured for n = 1 to 4 jet events. Our measurements are found to be in good agreement with a next-to-leading order QCD calculation and with a tree-level QCD prediction with parton shower simulation and hadronization.Comment: 7 pages, 2 figures, slightly modified, submitted to Phys. Lett.

Search for Supersymmetry in Di-Photon Final States at sqrt{s} = 1.96 TeV

We report results of a search for supersymmetry (SUSY) with gauge-mediated symmetry breaking in di-photon events collected by the D0 experiment at the Fermilab Tevatron Collider in 2002--2006. In 1.1 fb$^{-1}$ of data, we find no significant excess beyond the background expected from the standard model and set the most stringent lower limits to date for a standard benchmark model on the lightest neutralino and chargino masses of 125 GeV and 229 GeV, respectively, at 95% confidence

Search for squarks and gluinos in events with jets and missing transverse energy using 2.1 fb-1 of ppbar collision data at sqrt(s)=1.96 TeV

A data sample corresponding to an integrated luminosity of 2.1 fb-1 collected by the D0 detector at the Fermilab Tevatron Collider was analyzed to search for squarks and gluinos produced in ppbar collisions at a center-of-mass energy of 1.96 TeV. No evidence for the production of such particles was observed in topologies involving jets and missing transverse energy, and 95% C.L. lower limits of 379 GeV and 308 GeV were set on the squark and gluino masses, respectively, within the framework of minimal supergravity with tan(beta)=3, A0=0, and mu<0. The corresponding previous limits are improved by 54 GeV and 67 GeV

Search for the lightest scalar top quark in events with two leptons in p-pbar collisions at sqrt(s) = 1.96 TeV

Data collected by the D0 detector at a p-pbar center-of-mass energy of 1.96 TeV at the Fermilab Tevatron Collider have been used to search for pair production of the lightest supersymmetric partner of the top quark decaying into $b \ell \tilde{\nu}$. The search is performed in the $\ell\ell' = e\mu$ and $\mu \mu$ final states. No evidence for this process has been found in data samples of approximately 400 pb^-1. The domain in the [$M(\tilde{t}_1),M(\tilde{\nu})$] plane excluded at the 95% C.L. is substantially extended by this search.Comment: 9 pages, 11 figures. Selection-cut layouts slightly different than in PL