Erratum: A Lattice Study of the Two-photon Decay Widths for Scalar and Pseudo-scalar Charmonium [Chinese Physics C Vol.44,No.8(2020)083108]

We have corrected the decay width for the two photon decay widths for scalar and pseudo-scalar Charmonium in [Chinese Physics C Vol.44,No.8(2020)083108]. The decay widths are now in better agreement with the experiment values.

Heavy-quark mesons in the diabatic approach: string breaking and the quarkoniumlike spectrum

The Born-Oppenheimer approximation provides a description of heavy-quark mesons firmly based on lattice QCD, but its validity is limited to the lightest states lying far below the first open-flavour meson-meson threshold. This limitation can be overcome in the diabatic framework, a formalism first introduced in molecular physics, where the dynamics is encoded in a potential matrix whose elements can be derived from unquenched lattice QCD studies of string breaking. The off-diagonal elements of the potential matrix provide interaction between heavy quark-antiquark and meson-meson pairs, from which the mixing of quarkonium states with molecular components and the OZI-allowed strong decay widths are directly calculated. This allows for a QCD-based unified description of conventional quarkonium and unconventional mesons containing quark-antiquark and meson-meson components, what has proved to be successful for charmoniumlike and bottomoniumlike resonances.

$$A=4-7$$ $$\varXi $$ hypernuclei based on interactions from chiral effective field theory

We investigate the existence of bound $$\varXi $$ Ξ states in systems with $$A=4-7$$ A = 4 - 7 baryons using the Jacobi NCSM approach in combination with chiral NN and $$\varXi $$ Ξ N interactions. We find three shallow bound states for the NNN$$\varXi $$ Ξ system (with $$(J^\pi ,T)=(1^+,0)$$ ( J π , T ) = ( 1 + , 0 ) , $$(0^+,1)$$ ( 0 + , 1 ) and $$(1^+,1)$$ ( 1 + , 1 ) ) with quite similar binding energies. The $$^5_{\varXi }\mathrm {H}(\frac{1}{2}^+,\frac{1}{2})$$ Ξ 5 H ( 1 2 + , 1 2 ) and $$^7_{\varXi }\mathrm {H}(\frac{1}{2}^+,\frac{3}{2})$$ Ξ 7 H ( 1 2 + , 3 2 ) hypernuclei are also clearly bound with respect to the thresholds $$^4\mathrm {He} + \varXi $$ 4 He + Ξ and $$^6\mathrm {He} +\varXi $$ 6 He + Ξ , respectively. The binding of all these $$\varXi $$ Ξ systems is predominantly due to the attraction of the chiral $$\varXi $$ Ξ N potential in the $$^{33}S_1$$ 33 S 1 channel. A perturbative estimation suggests that the decay widths of all the observed states could be rather small.

Next-to-leading-order QCD corrections to a vector bottomonium radiative decay into a charmonium

Within the framework of nonrelativistic QCD (NRQCD) factorization, we calculate the next-to-leading-order (NLO) perturbative corrections to the radiative decay Υ → ηc(χcJ) + γ. Both the helicity amplitudes and the helicity decay widths are obtained. It is the first computation for the processes involving both bottomonium and charmonium at two-loop accuracy. By employing the Cheng-Wu theorem, we are able to convert most of complex-valued master integrals (MIs) into real-valued MIs, which makes the numerical integration much efficient. Our results indicate the $$ \mathcal{O}\left({\alpha}_s\right) $$ O α s corrections are moderate for ηc and χc2 production, and are quite marginal for χc0 and χc1 production. It is impressive to note the NLO corrections considerably reduce the renormalization scale dependence in both the decay widths and the branching fractions for χcJ, and slightly improve that for ηc. With the NRQCD matrix elements evaluated via the Buchmüller-Tye potential model, we find the decay width for ηc production is one-order-of-magnitude larger than χcJ production, which may provide a good opportunity to search for Υ → ηc + γ in experiment. In addition, the decay width for χc1 production is several times larger than those for χc0,2. Finally, we find the NLO NRQCD prediction for the branching fraction of Υ → χc1 + γ is only half of the lower bound of the experimental data measured recently by Belle. Moreover, there exists serious contradiction between theory and experiment for Υ → ηc + γ. The discrepancies between theory and experiment deserve further research efforts.

Deciphering weak decays of triply heavy baryons by SU(3) analysis

Baryons with three heavy quarks are the last missing pieces of the lowest-lying baryon multiplets in the quark model after the discovery of doubly heavy baryons. In this work, we study nonleptonic weak decays of triply heavy baryons $$\Omega _{ccc}^{++}$$ Ω ccc + + , $$\Omega _{bbb}^{-}$$ Ω bbb - , $$\Omega _{ccb}^{+}$$ Ω ccb + , and $$\Omega _{cbb}^{0}$$ Ω cbb 0 . Decay amplitudes for various processes have been parametrized in terms of the SU(3) irreducible nonperturbative amplitudes. A number of relations for the partial decay widths can be deduced from these results that can be examined in future. Some decay channels and cascade decay modes which likely to be used to reconstruct the triply heavy baryons have been also listed.

Strong and electromagnetic decays of the radially excited $$D_s$$ and $$B_s$$ mesons in light cone QCD sum rules

Recently, LHCb Collaboration announced the discovery of radial excitations of $$D_s$$ D s and $$B_s$$ B s mesons. In present work, we calculate the most promising strong and electromagnetic decay widths of radially excited $$D_s(2S)$$ D s ( 2 S ) and $$B_s(2S)$$ B s ( 2 S ) mesons within the light cone QCD sum rules method.

The LFU ratio $$R_\pi $$ in the Standard Model and beyond

We discuss the possibility of performing precise tests of $$\mu /e$$ μ / e universality in $$B \rightarrow \pi \ell ^+\ell ^-$$ B → π ℓ + ℓ - decays. We show that in wide regions of the dilepton invariant mass spectrum the ratio between muonic and electronic decay widths can be predicted with high accuracy, both within and beyond the Standard Model. We present numerical expressions which can be used to extract precise information on short-distance dynamics if a deviation from universality is observed in the data.

Development of a Monte-Carlo Evaporation Code for Multiple-Fragment Emission

An extended Hauser-Feshbach approach has been employed in a multi-step Monte-Carlo evaporation code designed to study the de-excitation of highly excited compound nuclei. The code is intended to account for emission of light particles ($\gamma$, n, $^{1,2,3}$H, $^{3-6}$He) and intermediate mass fragments in their ground and excited states (particle-bound or unbound). As a study case, we consider the decay of the compound nucleus $^{120}$Te$^*$ at excitation energy 100, 200 and 300 MeV. First chance decay widths are compared with treatments based on the Weisskopf and the s-wave approximation. Preliminary calculations are compared with experimental isotopic yields of intermediate mass fragments emitted in E/A = 50 MeV $^{4}$He + $^{116,124}$Sn $\rightarrow$ $^{120,128}$Te$^*$ reactions.