Search results for "quarkonium"
showing 10 items of 92 documents
Charged charmonium molecules
2010
We make use of a self-consistent quark-model based study of four-quark charmonium-like states to interpret recent charmonium experimental data. We conclude that there exists a ${D}^{*}{\overline{D}}^{*}$ meson-meson molecule with quantum numbers $({I}^{G}){J}^{PC}=({1}^{\ensuremath{-}}){2}^{++}$. Our study confirms the presence of charged charmonium-like resonances on the excited charmonium spectrum. We find support from recent experimental data by the Belle Collaboration [R. Mizuk et al. (Belle Collaboration), Phys. Rev. D 78, 072004 (2008)]. Confirmation of the experimental data by the Belle Collaboration and the determination of the quantum numbers of the new structures would help in dis…
Experimental determination of in DELPHI
1998
The running mass of the b quark as defined in the MS renormalization scheme, mb, was measured at the MZ scale using 2.8 million hadronic Z0 decays collected by the DELPHI experiment at LEP. The result is mb(MZ) = 2.67 ± 0.25(stat.) ± 0.34(frag.) ± 0.27(theo.)GeV/c2 which differs from that obtained at the γ scale, by mb(Mγ2)−mb(MZ) = 1.49±0.52 GeV/c2. This measurement, performed far from the bb production threshold, provides the first experimental observation of the running of the quark masses.
Search for γγ→ηb in e+e− collisions at LEP 2
2002
A search for the pseudoscalar meson eta_b is performed in two-photon interactions at LEP~2 with an integrated luminosity of 699 pb^-1 collected at e+e- centre-of-mass energies from 181 GeV to 209 GeV. One candidate event is found in the six-charged-particle final state and none in the four-charged-particle final state, in agreement with the total expected background of about one event. Upper limits of Gamma_gammagamma(eta_b) * BR(eta_b -> 4 charged particles) 6 charged particles) < 132 eV are obtained at 95% confidence level, which correspond to 95% confidence level upper limits of 9.0% and 25% on these branching ratios.
Heavy quarkonium: progress, puzzles, and opportunities
2011
A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the $B$-factories and CLEO-c flo…
Two-photon and one-photon–one-vector meson decay widths of thef0(1370),f2(1270),f0(1710),f2′(1525), andK2*(1430)
2010
We calculate the radiative decay widths, two-photon ($\ensuremath{\gamma}\ensuremath{\gamma}$) and one-photon--one-vector meson ($V\ensuremath{\gamma}$), of the dynamically generated resonances from vector-meson--vector-meson interaction in a unitary approach based on the hidden-gauge Lagrangians. In the present paper we consider the following dynamically generated resonances: ${f}_{0}(1370)$, ${f}_{0}(1710)$, ${f}_{2}(1270)$, ${f}_{2}^{\ensuremath{'}}(1525)$, ${K}_{2}^{*}(1430)$, two $\mathrm{\text{strangeness}}=0$ and $\mathrm{\text{isospin}}=1$ states, and two $\mathrm{\text{strangeness}}=1$ and $\mathrm{\text{isospin}}=1/2$ states. For the ${f}_{0}(1370)$ and ${f}_{2}(1270)$ we reproduc…
QQ-onia package: a numerical solution to the Schrodinger radial equation for heavy quarkonium
2008
30 pages, 3 figures.-- ISI article identifier:000265158700009.-- ArXiv pre-print avaible at: http://arxiv.org/abs/0805.2704
Search for the Xb and other hidden-beauty states in the π+π−ϒ(1S) channel at ATLAS
2015
This Letter presents a search for a hidden-beauty counterpart of the X(3872) in the mass ranges 10.05--10.31 GeV and 10.40--11.00 GeV, in the channel Xb→π+π−Υ(1S)(→μ+μ−), using 16.2 fb−1 of s√=8 TeV pp collision data collected by the ATLAS detector at the LHC. No evidence for new narrow states is found, and upper limits are set on the product of the Xb cross section and branching fraction, relative to those of the Υ(2S), at the 95% confidence level using the CLS approach. These limits range from 0.8% to 4.0%, depending on mass. For masses above 10.1 GeV, the expected upper limits from this analysis are the most restrictive to date. Searches for production of the Υ(13DJ), Υ(10860), and Υ(110…
Tree-level flavor-changing neutral currents in theBsystem: FromCPasymmetries to rare decays
2001
corresponding to 0.59 ≤ sin(2�) ≤ 0.82, which is cer- tainly outside the 1� Babar range but not outside the world average. This potential discrepancy is at the ori- gin of several papers (6) studying the implications of a small aJ/ in the search of new physics. In this paper, we analyze the implications of this situ- ation for a realistic model, obtained with the only addi- tion of an isosinglet down vector-like quark (7) to the SM spectrum. This model naturally arises, for instance, as the low-energy limit of an E6 grand unified theory. At a more phenomenological level, models with isosinglet quarks provide the simplest self-consistent framework to study deviations of 3 ×3 unitarity of the…
Search forfJ(2220)in RadiativeJ/ψDecays
2010
We present a search for f_(J)(2220) production in radiative J/ψ→γf_(J)(2220) decays using 460 fb^(-1) of data collected with the BABAR detector at the SLAC PEP-II e^(+)e^(-) collider. The f_(J)(2220) is searched for in the decays to K^(+)K^(-) and K_(S)^(0)K_(S)^(0). No evidence of this resonance is observed, and 90% confidence level upper limits on the product of the branching fractions for J/ψ→γf_(J)(2220) and f_(J)(2220)→K^(+)K^(-)(K_(S)^(0)K_(S)^(0)) as a function of spin and helicity are set at the level of 10^(-5), below the central values reported by the Mark III experiment.
Search for a low-mass scalar Higgs boson decaying to a tau pair in single-photon decays of Y(1S)
2013
We search for a low-mass scalar CP-odd Higgs boson, A(0), produced in the radiative decay of the upsilon resonance and decaying into a tau(+)tau(-) pair: Y(1S) -> gamma A(0). The production of Y(1S) mesons is tagged by Y(2S) -> pi(+)pi(-) Y(1S) transitions, using a sample of (98.3 +/- 0.9) x 10(6) Y(2S) mesons collected by the BABAR detector. We find no evidence for a Higgs boson in the mass range 3: 5 <= m(A)0 <= 9: 2 GeV, and combine these results with our previous search for the tau decays of the light Higgs in radiative Y(3S) decays, setting limits on the coupling of A(0) to the b (b) over bar quarks in the range 0.09-1.9. Our measurements improve the constraints on the parameters of th…