Search results for "meson"
showing 10 items of 1548 documents
HEAVY HADRON SPECTROSCOPY: A QUARK MODEL PERSPECTIVE
2012
We present recent results of hadron spectroscopy and hadron hadron interaction from the perspective of constituent quark models. We pay special attention to the role played by higher-order hock space components in the hadron spectra and the connection of this extension with the hadron-hadron interaction. The main goal of our description is to obtain a coherent understanding of the low-energy hadron phenomenology without enforcing any particular model, to constrain its characteristics and learn about the low-energy realization of the theory.
Evidence for B$^{0}_{s}$ meson production in Z$^0$ decays
1992
Seven unambiguous events out of a sample of 270 000 Z0 decays, contain in tile same jet a D(s) meson and a muon at large transverse momentum relative to the et axis. These events are direct evidence for B(s)0 meson production in hadronic Z0 decays. The production rate of these events, relative to all hadronic Z0 decays is ( 18 +/- 8) x 10(-5) this number including the relevant branching fractions of the B(s)0 and D(s). The value of the B(s)0 meson lifetime relative to the average B meson lifetime is measured to be 0.8 +/- 0.4.
Charged lepton induced one kaon production off the nucleon
2013
We study single kaon production off the nucleon induced by electrons (positrons) i.e., e(-) (e(+)) + N -> v(e) ((v) over bar (e)) + (K) over bar (K) + N' at low energies. The possibility of observing these processes with the high luminosity beams available at TJNAF and Mainz is discussed, taking into account that the strangeness conserving electromagnetic reactions have a higher energy threshold for (K) over bar (K) production. The calculations are done using a microscopic model that starts from the SU(3) chiral Lagrangians and includes background terms and the resonant mechanisms associated to the lowest lying resonance Sigma*(1385)
Study of the exclusive initial-state-radiation production of the D¯¯¯D system
2006
A study of exclusive production of the $D \bar D$ system through initial-state r adiation is performed in a search for charmonium states, where $D=D^0$ or $D^+$. The $D^0$ mesons are reconstructed in the $D^0 \to K^- \pi^+$, $D^0 \to K^- \pi^+ \pi^0$, and $D^0 \to K^- \pi^+ \pi^+ \pi^-$ decay modes. The $D^+$ is reconstructed through the $D^+ \to K^- \pi^+ \pi^+$ decay mode. The analysis makes use of an integrated luminosity of 288.5 fb$^{-1}$ collected by the BaBar experiment. The $D \bar D$ mass spectrum shows a clear $\psi(3770)$ signal. Further structures appear in the 3.9 and 4.1 GeV/$c^2$ regions. No evidence is found for Y(4260) decays to $D \bar D$, implying an up per limit $\frac{\…
Global analysis of fragmentation functions for eta mesons
2011
Fragmentation functions for eta mesons are extracted at next-to-leading order accuracy of QCD in a global analysis of data taken in electron-positron annihilation and proton-proton scattering experiments. The obtained parametrization is in good agreement with all data sets analyzed and can be utilized, for instance, in future studies of double-spin asymmetries for single-inclusive eta production. The Lagrange multiplier technique is used to estimate the uncertainties of the fragmentation functions and to assess the role of the different data sets in constraining them.
Measurement ofCP-violating asymmetries inB0→(ρπ)0decays using a time-dependent Dalitz plot analysis
2012
We report on a measurement of CP-violating asymmetries (A{sub CP}) in the Cabibbo-suppressed D{sup 0} {yields} {pi}{sup +}{pi}{sup -} and D{sup 0} {yields} K{sup +}K{sup -} decays reconstructed in a data sample corresponding to 5.9 fb{sup -1} of integrated luminosity collected by the upgraded Collider Detector at Fermilab. We use the strong decay D*{sup +} {yields} D{sup 0}{pi}{sup +} to identify the flavor of the charmed meson at production and exploit CP-conserving strong c{bar c} pair-production in p{bar p} collisions. High-statistics samples of Cabibbo-favored D{sup 0} {yields} K{sup -}{pi}{sup +} decays with and without a D*{sup {+-}} tag are used to correct for instrumental effects an…
Observation and studies of double J/psi production at the Tevatron
2014
We present the observation of doubly-produced $J/\psi$ mesons with the D0 detector at Fermilab in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV. The production cross section for both singly and doubly-produced $J/\psi$ mesons is measured using a sample with an integrated luminosity of 8.1fb$^{-1}$. For the first time, the double $J/\psi$ production cross section is separated into contributions due to single and double parton scatterings. Using these measurements, we determine the effective cross section $\sigma_{eff}$, a parameter characterizing an effective spatial area of the parton-parton interactions and related to the parton spatial density inside the nucleon.
Study of radiative bottomonium transitions using converted photons
2011
We use 111+/-1 million Upsilon(3S) and 89+/-1 million Upsilon(2S) events recorded by the BaBar detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions between bottomonium states using photons that have been converted to e+e- pairs by the detector material. We observe Upsilon(3S) -> gamma chi_b0,2(1P) decay, make precise measurements of the branching fractions for chi_b1,2(1P,2P) -> gamma Upsilon(1S) and chi_b1,2(2P) -> gamma Upsilon(2S) decays, and search for radiative decay to the eta_b(1S) and eta_b(2S) states.
Search for exclusive charmless b meson decays with the Delphi detector at Lep
1995
Charmless hadronic decays of beauty mesons have been searched for using the data collected with the DELPHI detector at the LEP collider. Several two, three and four-body decay modes have been investigated. Particle identification was used to distinguish the final states with protons, kaons and pions. Three candidate events selected in two-body decay modes are interpreted as evidence for charmless B decays. No excess has been found in higher multiplicity modes and improved upper limits for some of the branching ratios are given. © 1995.
Measurement ofD0−D¯0mixing using the ratio of lifetimes for the decaysD0→K−π+andK+K−
2009
We present a measurement of ${D}^{0}\mathrm{\text{\ensuremath{-}}}{\overline{D}}^{0}$ mixing and $CP$ violation using the ratio of lifetimes simultaneously extracted from a sample of ${D}^{0}$ mesons produced through the flavor-tagged process ${D}^{*+}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{+}$, where ${D}^{0}$ decays to ${K}^{\ensuremath{\mp}}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$, ${K}^{\ensuremath{-}}{K}^{+}$, or ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$, along with the untagged decays ${D}^{0}\ensuremath{\rightarrow}{K}^{\ensuremath{\mp}}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$ and ${D}^{0}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{K}…