Mass spectra and leptonic decay widths of heavy quarkonia

A nonrelativistic Hamiltonian with plausible spin dependent corrections is proposed for the quarkonia below their respective strong decay thresholds. With only six free parameters this model reproduces the nine known masses of the bottomonia within about 1 MeV, the six known masses of the charmonia within a few MeV and the five known leptonic decay widths of the states within about 20%. The model is then used to predict the masses of the remaining 43 qu arkonia (some of them for the first time) and of the leptonic decay widths of the two states. Comparison with some other models is made. Received: 17 June 1997     

Radiative corrections in heavy quarkonia

We investigate radiative corrections in heavy quarkonia and calculate relativistic corrections which are not taken into account in earlier papers. It appears that these terms cannot be neglected as compared to the usually calculated radiative corrections and lead to a considerable contribution to the level splittings.     

Exotic vector charmonium and its leptonic decay width

We propose a novel type of interpolating field operator,which manifests the hybrid-like configuration that the charm quark-antiquark pair recoils against gluonic degrees of freedom.A heavy vector charmonium-like state with a mass of 4.33(2) GeV is disentangled from the conventional charmonium states in the quenched approximation.This state has affinity for the hybrid-like operators but couples less to the relevant quark bilinear operator.We also try to extract its leptonic decay constant and give a tentative upper limit that it is less than one tenth of that of J/ψ,which corresponds to a leptonic decay width about dozens of eV.The connection of this state with X(4260) is also discussed.     

Duality and radiative corrections to leptonic widths in heavy quark systems

We use a duality argument to estimate the gluonic radiative corrections of orders α_s and α_s² to the leptonic widths for heavy quark systems.     

Comment on the hadronic decay of excited heavy quarkonia

We make comments on [1], and provide partial wave analysis to the decays of excited heavy S-wave quarkonia into the basic quarkonia state plus . It is revealed that there exist contributions of D-wave transition in , and by using the data-fitting results in [1]. A possible experimental method to measure the D-wave directly is discussed. Received: 14 May 1998 / Published online: 21 September 1998     

Factorization of radiative leptonic D-meson decay with sub-leading power corrections

In this work,we calculate the sub-leading power contributions to radiative leptonic D→γlv decay.For the first time,we provide the analytic expressions of next-to-leading power contributions and the error estimation associated with the power expansion of O(A_(QCD)/m_c).In our calculation,we adopt two different models of the Dmeson distribution amplitudes Φ_(D,Ⅰ)~+ and Φ_(D,Ⅱ)~+.Within the framework of QCD factorization as well as the dispersion relation,we evaluate the soft contribution up to the next-to-leading logarithmic accuracy and also consider the higher-twist contribution from the two-particle and three-particle distribution amplitudes.Finally,we find that all the sub-leading power contributions are significant at λ_D(μ_0)=354 MeV,and the next-to-leading power contributions lead to 143% in Φ_(D,Ⅰ)+ and 120% in Φ_(D,Ⅱ)~+ corrections to leading power vector form factors with E_γ=0.5 GeV.As the corrections from the higher-twist and local sub-leading power contributions are enhanced with increasing inverse moment,it is difficult to extract an appropriate inverse moment of the D-meson distribution amplitude.The predicted branching fractions are(1.88_(-0.29)~(+0.36)) × 10~(-5) for Φ_(D,Ⅰ)~+ and(2.31_(-0.54)~(+0.65))× 10~(-5) for Φ_(D,Ⅱ)~+.     

Electroweak corrections to the fermionic decay width of the standard Higgs boson

The partial decay width of the standard model Higgs particle into a general species of fermions is given at the electroweak 1-loop level. The analytic formulae are applicable to light and heavy fermions. Numerical results are presented for Higgs decays intob andt quarks and into charged leptons. For not too heavy Higgs bosons the radiative corrections are of the order of a few per cent. In particular for Higgs bosons below theW ⁺ W ^– threshold the correction to the partial width intob quarks is very small and insensitive to the top mass. For every heavy Higgs bosons the 1-loop corrections increase the fermionic decay widths for all channels up to 15%.     

Spectroscopy and Regge trajectories of heavy quarkonia in the relativistic quark model

The mass spectra of charmonia and bottomonia are calculated in the framework of the relativistic quark model up to high orbital and radial excitations. The Regge trajectories of heavy quarkonia are constructed both in the (J,M ²) and (n _r ,M ²) planes, where J is the total angular momentum and nr is the radial quantum number. All daughter trajectories turn out to be almost linear and parallel, while parent trajectories exhibit some nonlinearity. Such nonlinearity occurs only in the vicinity of ground states and few lowest excitations and is more pronounced for bottomonia, while it is only marginal for charmonia. The obtained results are compared with available experimental data, and a possible interpretation of the new charmonium-like states above open charm production threshold is discussed.     

On the leptonic decay of a heavy quarkonium with a Higgs-boson emission

The leptonic () decay of a heavy quark-antiquark bound state T( Q) with a Higgs-boson H emission is investigated. Applying the low-energy theorem to meson-Higgs coupling allows one to estimate the probability of the decay T( Q) → H. Only the simple version of the Standard Model extension containing two-Higgs doublet is considered. The text was submitted by the author in English.     

New theory of positronium decay and relativistic wave function corrections

The positronium decay rate is calculated directly from the scattering amplitude by analytic continuation to the bound-state singularities. Relativistic wave function corrections are obtained which improve the agreement between theory and experiment.     

A nonperturbative treatment of radiative decays and the relativistic kinetic energy in heavy quarkonia

Using a “regularized potential” we solve the Schrödinger equation including all spin dependent interactions nonperturbatively and calculate the radiative decays of heavy quarkonia. The influence ofS-D mixing due to the tensor term is discussed. Applying the variational approach we investigate the influence of the relativistic kinetic energy on the bound state masses.     

QCD corrections to electroweak annihilation decays of superheavy quarkonia

QCD corrections to all the allowed decays of superheavy groundstate quarkonia into electroweak gauge and Higgs bosons are presented. For quick estimates, approximations that reproduce the exact results within less than at worst one percent are also given.