نتایج جستجو برای: mesons
تعداد نتایج: 13462 فیلتر نتایج به سال:
The masses of S0 and S1 mesons containing a single heavy quark are computed in the quenched approximation. The light quark action and gauge field action are both classically-improved and tadpole-improved, and the couplings to the heavy quark are organized by the 1/M expansion of tadpole-improved NRQCD. At each of two lattice spacings, near 0.22fm and 0.26fm, meson masses are obtained for heavy ...
In the heavy quark and large Nc limits, ordinary (exotic) heavy baryons can be considered as bound states of heavy mesons (anti-mesons)and chiral solitons. In these limits, the heavy mesons (or anti-mesons) and the chiral solitons are extremely heavy and are presumed to fall to the bottom of the effective potential. Previous studies have approximated the effective potential as harmonic about th...
We argue that those field theories containing mesons that are dual to weakly curved string backgrounds are non–generic. The spectrum of highly excited mesons in confining field theories behaves as Mn ∝ √ n (where n is the radial excitation number), as does the spectrum of the dual mesons described by open strings ending on probe D branes. However, in the weakly coupled backgrounds, we show that...
We generalize Schwinger’s original mass formula to the case of an additional isosinglet which mixes with the nonet mesons, by considering the corresponding 3×3 mass matrix in the most general case. We then make further generalization to either (i) an arbitrary number of additional isosinglets mixing with nonet mesons, or (ii) an arbitrary number of mesons with common J mixing with an additional...
B̄ → Dπ, D∗π, J/ψK̄ and J/ψπ decays are studied. Their amplitude is given by a sum of factorized and non-factorizable ones. The latter which is estimated by using a hard pion approximation is rather small in color favored B̄ → Dπ and D∗π decays but still can efficiently interfere with the main amplitude given by the factorization. In the color suppressed B̄ → J/ψK̄ and J/ψπ decays, the non-factoriza...
We have searched for two-body charmless decays of B mesons to purely hadronic exclusive final states including ω or φ mesons using data collected with the CLEO II detector. With this sample of 6.6 × 106 B mesons we observe a signal for the ωK+ final state, and measure a branching fraction of B(B+ → ωK+) = (1.5 −0.6 ± 0.2) × 10−5. We also observe some evidence for the φK final state, and upper l...
Production of final states containing open charm (c) and beauty (b) quarks at HERA is reviewed. Photoproduction (PHP) of the charm meson resonances D∗, D and Ds, as well as D∗ production in the deep inelastic scattering (DIS) regime, are measured and compared to QCD predictions. The excited charm mesons D 1(2420), D ∗0 2 (2460) and D ± s1(2536) have been observed and the rates of charm quarks h...
There are striking regularities in the masses and mass differences of known hadrons. Some of these regularities can be understood from known general properties of the interactions of quarks without a need to specify the explicit form of the Hamiltonian. The Feynman–Hellmann theorem is one of the tools providing this understanding. If the mass regularities are exploited, predictions can be made ...
removes spurious selection rule forbidding processes with odd number of Goldstone mesons. Pseudoscalar mesons are produced in e+e− annihilation via vector resonances, hence one should include vector mesons in a chiral invariant way. The problem of testing chiral models of the vector meson interactions with Goldstone bosons is acute because in well studied decays ρ → 2π, ω → 3π the final pions a...
The main elements and methods of chiral perturbation theory, the effective field theory of the Standard Model below the scale of spontaneous chiral symmetry breaking, are summarized. Applications to the interactions of mesons and baryons at low energies are reviewed, with special emphasis on developments of the last three years. Among the topics covered are the strong, electromagnetic and semil...
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