Search NASA⌕ Search

SEARCH · Search NASA

Results for “VECTOR MESONS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Observation of B - →$\bar{p}$ΛD 0 at Belle

We study B- meson decays to $\bar{p}$ΛD (*)0 final states using a sample of 657×10 6 B$\bar{B}$ events collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e - collider. The observed branching fraction for B - →$\bar{p}$ΛD 0 is (1.43$+0.28\atop{-0.25}$±0.18)×10 -5 with a significance of 8.1 standard deviations, where the uncertainties are statistical and systematic, respectively. Most of the signal events have the $\bar{p}$ Λ mass peaking near threshold. No significant signal is observed for $\bar{p}$ΛD (*)0 and the corresponding upper limit on the branching fraction is 4.8×10 -5 at the 90% confidence level.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Dipion invariant mass distribution of the anomalous {Upsilon}(1S){pi}{sup +}{pi}{sup -} and {Upsilon}(2S){pi}{sup +}{pi}{sup -} production near the peak of {Upsilon}(10860)

Considering the defects of the previous work for estimating the anomalous production rates of e{sup +}e{sup -}{yields}{Upsilon}(1S){pi}{sup +}{pi}{sup -}, {Upsilon}(2S){pi}{sup +}{pi}{sup -} near the peak of the {Upsilon}(5S) resonance at {radical}(s)=10.87 GeV [K. F. Chen et al. (Belle Collaboration), Phys. Rev. Lett. 100, 112001 (2008)], we suggest a new scenario where the contributions from the direct dipion transition and the final-state interactions interfere to result in not only the anomalously large production rates, but also line shapes of the differential widths consistent with experimental measurement when assuming the reactions are due to the dipion emission of {Upsilon}(5S). At the end, we raise a new puzzle that the predicted differential width d{Gamma}({Upsilon}(5S){yields}{Upsilon}(2S){pi}{sup +}{pi}{sup -})/dcos{theta} has a discrepant trend from the data while other predictions are well in accord with the data. It should be further clarified by more accurate measurements carried by future experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Charged bottomoniumlike states Z{sub b}(10610) and Z{sub b}(10650) and the {Upsilon}(5S){yields}{Upsilon}(2S){pi}{sup +}{pi}{sup -} decay

Inspired by the newly observed two charged bottomoniumlike states, we consider the possible contribution from the intermediate Z{sub b}(10610) and Z{sub b}(10650) states to the {Upsilon}(5S){yields}{Upsilon}(2S){pi}{sup +}{pi}{sup -} decay process, which naturally explains Belle's previous observation of the anomalous {Upsilon}(2S){pi}{sup +}{pi}{sup -} production near the peak of {Upsilon}(5S) at {radical}(s)=10.87 GeV [K. F. Chen et al. (Belle Collaboration), Phys. Rev. Lett. 100, 112001 (2008)]. The resulting d{Gamma}({Upsilon}(5S){yields}{Upsilon}(2S){pi}{sup +}{pi}{sup -})/dm{sub {pi}}{sup +}{sub {pi}}{sup -} and d{Gamma}({Upsilon}(5S){yields}{Upsilon}(2S){pi}{sup +}{pi}{sup -})/dcos{theta} distributions agree with Belle's measurement after inclusion of these Z{sub b} states. This formalism also reproduces the Belle observation of the double-peak structure and its reflection in the {Upsilon}(2S){pi}{sup +} invariant mass spectrum of the {Upsilon}(5S){yields}{Upsilon}(2S){pi}{sup +}{pi}{sup -} decay.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

{phi} meson production in pp annihilation at rest

Apparent channel-dependent violations of the Okubo-Zwieg-Iizuka (OZI) rule in nucleon-antinucleon annihilation reactions in the presence of an intrinsic strangeness component in the nucleon are discussed. Admixture of ss quark pairs in the nucleon wave function enables the direct coupling to the {phi}-meson in the annihilation channel without violating the OZI rule. Three forms are considered in this work for the strangeness content of the proton wave function, namely, the uud cluster with a ss sea-quark component, kaon-hyperon clusters based on a simple chiral quark model, and the pentaquark picture uudss. Nonrelativistic quark model calculations reveal that the strangeness magnetic moment {mu}{sub s} and the strangeness contribution to the proton spin {sigma}{sub s} from the first two models are consistent with recent experimental data, where {mu}{sub s} and {sigma}{sub s} are negative. For the third model, the uuds subsystem with the configurations [31]{sub FS}[211]{sub F}[22]{sub S} and [31]{sub FS}[31]{sub F}[22]{sub S} leads to negative values of {mu}{sub s} and {sigma}{sub s}. With effective quark line diagrams incorporating the {sup 3}P{sub 0} model, we give estimates for the branching ratios of the annihilation reactions at rest pp{yields}{phi}X (X={pi}{sup 0}, {eta}, {rho}{sup 0}, {omega}). Results for the branching ratios of {phi}X production from atomic pp s-wave states are for the first and third model found to be strongly channel dependent, in good agreement with measured rates.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Electromagnetically superconducting phase of QCD vacuum induced by strong magnetic field

In this talk we discuss our recent suggestion that the QCD vacuum in a sufficiently strong magnetic field (stronger than 10{sup 16} Tesla) may undergo a spontaneous transition to an electromagnetically superconducting state. The possible superconducting state is anisotropic (the vacuum exhibits superconductivity only along the axis of the uniform magnetic field) and inhomogeneous (in the transverse directions the vacuum structure shares similarity with the Abrikosov lattice of an ordinary type-II superconductor). The electromagnetic superconductivity of the QCD vacuum is suggested to occur due to emergence of specific quark-antiquark condensates which carry quantum numbers of electrically charged rho mesons. A Lorentz-covariant generalization of the London transport equations for the magnetic-field-induced superconductivity is given.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Lepton event rates in neutrino-nucleus DIS

In this work we have studied the nuclear effect in F{sub 2}{sup A}(x) and F{sub 3}{sup A}(x) weak structure functions and calculated {nu}-nucleus cross section using them by taking into account Fermi motion, binding energy, pion and rho meson cloud contributions and shadowing and anti-shadowing effects. The numerical calculations have been performed in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. The results have been compared with the experimental results of NuTeV and CDHSW collaborations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Photoproduction of the rho meson and its magnetic moments

We study photoproduction of {rho} meson in a model of hidden local symmetry. We introduce the {rho} meson on a hidden gauge boson and phenomenological {rho} meson-nucleon Lagrangian is constructed respecting chiral symmetry. It turns out that the {sigma}-exchange interaction plays an important role in neutral {rho} meson photoproduction to reproduce the experimental cross sections. In charged {rho} meson photoproduction, the model takes into account the {rho} meson magnetic moments from the three-point vertex in the kinetic terms. We show that the magnetic moment of the charged {rho} meson has a significant effect on the total cross sections in proportion to the photon energies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

First observation of radiative B⁰ → ΦK⁰γ decays and measurements of their time-dependent CP violation

We report the first observation of the radiative decay B⁰→ ΦK⁰γ using a data sample of 772 × 10⁶ BB¯ pairs collected at the (4S) resonance with the Belle detector at the KEKB asymmetric-energy e⁺e⁻ collider. We observe a signal of 37 ± 8 events with a significance of 5.4 standard deviations including systematic uncertainties. The measured branching fraction is B(B⁰→ ΦK⁰γ) = (2.74±0.60±0.32)×10⁻⁶, where the uncertainties are statistical and systematic, respectively. We also report the first measurements of time-dependent CP-violation parameters: S ΦK⁰ S γ = +0.74 ⁺0.72 –1.05 (stat) +0.10 –0.24 (syst) and A ΦK⁰ S γ = +0.35 ± 0.58(stat) +0.23 –0.10 (syst). Furthermore, we measure B(B⁺ → ΦK⁺γ) = (2.48 ± 0.30 ± 0.24) × 10⁻⁶, ACP = –0.03 ± 0.11 ± 0.08 and find that the signal is concentrated in the M ΦK mass region near threshold.

Sahoo, Himansu B.↗
DOE OSTI2011

Randall-Sundrum corrections to the width difference and CP-violating phase in B{sub s}{sup 0}-meson decays

We study the impact of the Randall-Sundrum setup on the width difference {Delta}{Gamma}{sub s} and the CP-violating phase {phi}{sub s} in the B{sub s}{sup 0}-B{sub s}{sup 0} system. Our calculations are performed in the general framework of an effective theory, based on operator product expansion. The results can thus be used for many new-physics models. We find that the correction to the magnitude of the decay amplitude {Gamma}{sub 12}{sup s} is below 4% for a realistic choice of input parameters. The main modification in the {Delta}{Gamma}{sub s}/{beta}{sub s}-plane is caused by a new CP-violating phase in the mixing amplitude, which allows for a better agreement with the experimental results of the CDF and D0 Collaborations from B{sub s}{sup 0}{yields}J/{psi}{phi} decays. The best-fit value of the CP asymmetry S{sub {psi}{phi}} can be reproduced, while simultaneously the theoretical prediction for the semileptonic CP asymmetry A{sub SL}{sup s} can enter the 1{sigma} range.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

m{sub {pi}} and N{sub c} dependence of {rho} and {sigma} mesons from unitarized chiral perturbation theory

We review the N{sub c} and m{sub {pi}} dependence of the {rho}(770) and {sigma}(or f{sub 0}(600)) resonances generated with the Inverse Amplitude Method. The {sigma}N{sub c} behavior is at odds with being dominantly a q-barq state, but there is a hint of a subdominant q-barq component with a mass above 1 GeV. We find fair agreement with lattice results for the chiral extrapolation of the {rho} mass, and that the {rho}{pi}{pi} coupling is almost m{sub {pi}} independent whereas the {sigma}{pi}{pi} coupling depends strongly on m{sub {pi}}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Recent Results from CLEO

The CLEO Experiment, utilizing symmetric e{sup +}e{sup -} collisions provided by the Cornell Electron Storage Ring (CESR) in the charmonium and bottomonium regions, has a wide-reaching program in the study of hadrons and the strong force. This review briefly summarizes recent contributions the CLEO Collaboration has made in the study of: (1) light quark systems (rare decays of the {eta}'); (2) charmonium radiative decays to light quarks (J/{psi} and {psi}(2S) radiative decays to the {eta} and {eta}'); (3) mesons with open charm (the D and D{sub s} decay constants); (4) charmonium transitions (a multipole analysis of {psi}(2S) {yields} {gamma}{chi}{sub c1,2} and {chi}{sub c1,2} {yields} {gamma}J/{psi}); and (5) bottomonium spectroscopy (confirming evidence for the discovery of the {eta}{sub b}(1S)).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Differential cross sections and spin density matrix elements for {gamma}p {yields} {phi}p from CLAS

Preliminary differential cross-sections and the {rho}{sub MM'}{sup 0} spin density matrix elements (SDME) for the reaction {gamma}{rho} {yields} {phi}p for both charged-({phi} {yields} K{sup +}K-) and neutral-mode ({phi} {yields} K{sub L}{sup 0}K{sub S}{sup 0}) topologies obtained from CLAS are presented. Our kinematic coverage is from near production threshold ({radical}(s){approx}1.97 GeV) to ({radical}(s) 2.84 GeV), with a wide coverage in the production angle. As seen in previous LEPS results, the differential cross-sections show a localized 'bump' between ({radical}(s){approx}2 and 2.2 GeV that is not expected from a simple Pomeron exchange picture. Comparisons between the charged- and neutral-mode results and possible effects from the K{sup +}{Lambda}(1520) channel are discussed. Our SDME results confirm the well-known deviations from t-channel helicity conservation (TCHC) for Pomeron exchange, but s-channel helicity conservation (SCHC) is also seen to be broken.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

In-Medium QCD Sum Rules for {rho}-Meson and Chiral Scale

In this talk, chiral scale, 4{pi}f{sub {pi}{approx}1} GeV, was introduced as an indicator of partial restoration of chiral symmetry at finite density or temperature, rather than the argument between mass shift and collisional broadening. We use the finite energy sum rules to determine the chiral scale identified with the separation scale of the low-energy resonance part from the high-energy continuum part of {rho}-meson spectral function. In this framework, in-medium {rho}-meson mass should be discussed in terms of the first two moments of the spectral function.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Search for charmonium and charmoniumlike states in Υ ( 2 S ) radiative decays

Using a sample of 158 x 10⁶ Υ(2S) events collected with the Belle detector, charmonium and charmoniumlike states with even charge parity are searched for in Υ(2S) radiative decays. No significant Xcl or nc signal is observed, and the following upper limits at 90% confidence level (C. L.) are obtained: Β(Υ(2S)→YXco)<1.0×10 - ⁴, Β(Υ(2S)→yxc1)<3.6×10 - ⁶, Β(Υ(2S)→yxc2)<1.5 x 10 - ⁵, and Β(Υ(2S)→ync)<2.7×10 - ⁵. No significant signal of any charmoniumlike state is observed, and we obtain the limits Β(Υ(2S)→yX(3872)) x Β(X(3872)→π⁺π⁻J/ψ)<0.8×10-6, Β(Υ(2S)→γX(3872))× Β(X(3872)→ π⁺π⁻π⁰Jlψ)<2.4 x 10⁻⁶, Β(Υ(2S)→γX(3915))× Β(X(3915)→ωJ/ψ)<2.8×10⁻⁶, Β(Υ(2S)→γY(4140)) x Β(Y(4140)→$\phi$J/ψ))<1.2 x 10 - ⁶, and Β(Υ(2S)→yX(4350))× Β(X(4350)→$\phi$J/ψ))<1.3×10⁻⁶ at 90% C. L.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗