Two-gluon Annihilation Research Articles

Mass shifts of P3J heavy quarkonia due to the effect of two-gluon annihilation

In this work, we calculate the nonrelativistic asymptotic behavior of the amplitudes of $q\overline{q}\rightarrow 2g \rightarrow q\overline{q}$ in the leading order of $\alpha_s$ (LO-$\alpha_s$) with $q\overline{q}$ in the $^3P_J$ channels. In the practical calculation we take the momenta of quarks and antiquarks on-shell and expand the amplitudes on the three-momentum of the quarks and antiquarks to order 6 and get three nonzero terms. The imaginary parts of the first term and the second term are the old. The real parts of the results have IR divergence. When applying the results to the heavy quarkonia, the corresponding amplitude of $q\overline{q}\rightarrow1g\rightarrow q\overline{q}$ with $q\overline{q}$ in the color octet $^3S_1$ channel is considered to absorb the IR divergence in a unitary way in the leading order of $v$ (LO-$v$). The finial results can be used to estimate the mass shifts of the $^3P_J$ heavy quarkonia due to the effect of two-gluon annihilation. The numerical estimation shows that the contributions to the mass shifts of $\chi_{c0,c1,c2}$ are about $1.23\sim1.58$ MeV, $1.57\sim1.86$ MeV and $5.92\sim5.45$ MeV when taking $\alpha_s\approx 0.25\sim0.35$.

Correction to the energy spectrum of S10 heavy quarkonia due to two-gluon annihilation effect

In this work, the non-relativistic asymptotic behavior of the transition $q\overline{q}\rightarrow2g\rightarrow q\overline{q}$ in the $^1S_0$ channel is discussed. Different with the usual calculation which expands the physical amplitude around the quark anti-quark threshold, we take the quark anti-quark pairs as off shell and only expand the expression on the three-dimensional momenta of the quarks and anti-quarks. We calculate the results to order 6. The imagine part of the results after applying the on shell conditions can reproduce the non-relativistic QCD (NRQCD) results in leading order of $\alpha_s$. The real part of the results can be used to estimate the mass shift of the $^1S_0$ heavy quark anti-quark system due to the $2g$ annihilation effect. The results can also be used to estimate the energy shifts of the positronium system due to the two-photon annihilation.

Exotics at Our Home

1. Light Scalars as Four-Quark States 2. Isotensor Tensor E(1500 - 1600) State 3. X(3872) State as Charmonium χc1(2P) 4. Two-gluon Annihilation of Charmonium χc2(2P)

Annihilation rate of heavy [formula omitted] P-wave quarkonium in relativistic Salpeter method

Two-photon and two-gluon annihilation rates of P-wave scalar charmonium and bottomonium up to third radial excited states are estimated in the relativistic Salpeter method. We solved the full Salpeter equation with a well-defined relativistic wave function and calculated the transition amplitude using the Mandelstam formalism. Our model dependent estimates for the decay widths: Γ ( χ c 0 → 2 γ ) = 3.78 keV , Γ ( χ c 0 ′ → 2 γ ) = 3.51 keV , Γ ( χ b 0 → 2 γ ) = 48.8 eV and Γ ( χ b 0 ′ → 2 γ ) = 50.3 eV . We also give estimates of total widths by the two-gluon decay rates: Γ tot ( χ c 0 ) = 10.3 MeV , Γ tot ( χ c 0 ′ ) = 9.61 MeV , Γ tot ( χ b 0 ) = 0.887 MeV and Γ tot ( χ b 0 ′ ) = 0.914 MeV .

Annihilation rate of heavy [formula omitted] quarkonium in relativistic Salpeter method

Two-photon and two-gluon annihilation rates of ηc, ηc′, ηb and ηb′ are estimated in the relativistic Salpeter method. By solving the full Salpeter equation with a well defined relativistic wave function, we estimate Mηc=2.979±0.432 GeV, Mηc′=3.566±0.437 GeV, Mηb=9.364±1.120 GeV and Mηb′=9.941±1.112 GeV. We calculated the transition amplitude using the Mandelstam formalism and estimate the decay widths: Γ(ηc→2γ)=7.14±0.95 keV, Γ(ηc′→2γ)=4.44±0.48 keV, Γ(ηb→2γ)=0.384±0.047 keV and Γ(ηb′→2γ)=0.191±0.025 keV. We also give estimates of total widths by the two-gluon decay rates: Γtot(ηc)=19.6±2.6 MeV, Γtot(ηc′)=12.1±1.3 MeV, Γtot(ηb)=6.98±0.85 MeV and Γtot(ηb)=3.47±0.45 MeV.

Hadron masses in cavity quantum chromodynamics to order $\alpha_{\rm s}^2$

The non-divergent diagrams describing two-gluon exchange and annihilation between quarks and antiquarks are calculated in the Feynman gauge, based on quantum chromodynamics in a spherical cavity. Using the experimental $N$, $\Delta$, $\Omega$, and $\rho$ masses to fit the free parameters of the M.I.T.\ bag model, the predicted states agree very well with the observed low-lying hadrons. As expected, the two-gluon annihilation graphs lift the degeneracy of the $\pi$ and $\eta$, while the $\rho$ and $\omega$ remain degenerate. Diagonalizing the $\eta - \eta'$ subspace Hamiltonian yields a very good value for the mass of the $\eta$ meson.

Mass spectra of higher states of quarkonia and decays for scalar-vector confining interaction

Recently, we have studied a flavour-independent potential for quark-antiquark systems of equal and unequal masses in which the confining interaction is scalar-vector admixture with dominant scalar interaction and the spin-dependent part of the potential has been obtained from the non-relativistic reduction of the Bethe-Salpeter kernel. This potential was found to explain the heavy-quark data well. In the present work we have obtained further affirmative tests of the model by calculating the mass spectra of higher levels as well as the confining contribution of the spin-orbit forces forL≥1 states of quarkonia. We have considered the annihilation processes and radiative transitions too. The former include leptonic decay, two-photon decay, two-gluon annihilation, three-photon decay and three-gluon annihilations.

Heavy-flavor production in proton-proton interactions

We present a model based on quantum chromodynamics for calculating the production of particles containing heavy quarks. The production of heavy quarks is due to two-gluon annihilation. Soft-gluon emission is assumed to create a random-phase situation. For $D$, $B$, and $K$ mesons we calculate transversemomentum distributions.

Four quark states and open charm production

We discuss and calculate the contribution of resonances to open charm production through two-gluon annihilation in nucleon—nucleon interaction. Four-quark resonances, if they exist, make an important contribution because of their strong coupling to two gluons.

Charmed particles from two-gluon annihilation in proton-proton collisions

We estimate the cross section for charmed particle production in proton-proton scattering. An analysis of all possible sources of charmed particles reveals that the dominant mechanism at high energy involves the annihilation of constituent gluon partons. This process is as effective as the annihilation of constituent quark and antiquark partons in proton-antiproton scattering. Our unorthodox conclusion is that proton-proton collisions are practically as effective as proton-antiproton collisions for the production of charmed particles, or for the production of states involving heavier quarks. Gluon-gluon collisions may also produce light quark pairs. The possible relation between this process and the observed rising pp total cross section is discussed.

Charmed particles from two-gluon annihilation in proton-proton collisions: H. M. Georgi, S. L. Glashow, M. E. Machacek, and D. V. Nanopoulos, Lyman Laboratory of Physics, Harvard University, Cambridge, Massachusetts 02138

Charmed particles from two-gluon annihilation in proton-proton collisions: H. M. Georgi, S. L. Glashow, M. E. Machacek, and D. V. Nanopoulos, Lyman Laboratory of Physics, Harvard University, Cambridge, Massachusetts 02138

Higgs Bosons from Two-Gluon Annihilation in Proton-Proton Collisions

We estimate the cross section for Higgs-boson production in proton-proton collisions. We find that most of the cross section comes from a two-gluon annihilation process, in which the gluons couple to Higgs bosons via heavy-quark loops.

Corrections to the two-gluon annihilation rates of paracharmonium states

The effect of a color anomalous magnetic moment and of the finite size of the charmonium system on the annihilation rate of paracharmonium into two gluons is considered. Although these effects can reduce this rate by a factor of 2 from its lowest-order value, there remains a large discrepancy for one of these states between the theoretical and experimental values.

Quark confinement potential and meson resonances

We investigate the meson spectroscopy and the decays of vector mesons in a quark-confining two-step potential model proposed earlier for the quark-antiquark system. The predictions for the low-lying spectra of ρ, ϕ, K and K* systems are, in general, found to be in good agreement with the observed masses. In addition to the threshold at 4.19 GeV, we predict that the Ψ system also contains the states at 3.94 GeV, 4.39 GeV, 4.74 GeV as ι=0 radial excitations in contrast to the predictions of other authors as ι=1 excitations. The results for the leptonic decays widths of vector mesons are found to be large as compared to the experimental values. Predictions are also made for the two-gluon annihilation rates of theP-wave charmed quark-antiquark bound state.