Based on previous studies that support the vector-vector molecular structure of the $f_2(1270)$, $f'_2(1525)$, $\bar{K}^{*\,0}_2(1430)$, $f_0(1370)$ and $f_0(1710)$ resonances, we make predictions for $ψ(2S)$ decay into $ω(ϕ) f_2(1270)$, $ω(ϕ) f'_2(1525)$, $K^{*0}(892) \bar{K}^{*\,0}_2(1430)$ and radiative decay of $Υ(1S),Υ(2S), ψ(2S)$ into $γf_2(1270)$, $γf'_2(1525)$, $γf_0(1370)$, $γf_0(1710)$. Agreement with experimental data is found for three available ratios, without using free parameters, and predictions are done for other cases.
Very recently, three new structures $Ξ_c(2923)^0$, $Ξ(2938)^0$, and $Ξ(2964)^0$ at the invariant mass spectrum of $Λ_c^{+}K^{-}$ observed by the LHCb Collaboration triggers a hot discussion about their inner structure. In this work, we study the strong decay mode of the newly observed $Ξ_c$ assuming that the $Ξ_c$ is a $\bar{D}Λ-\bar{D}Σ$ molecular state. With the possible quantum numbers $J^p=1/2^{\pm}$ and $3/2^{\pm}$, the partial decay widths of the $\bar{D}Λ-\bar{D}Σ$ molecular state into the $Λ_c^{+}K^{-}$, $Σ_c^{+}K^{-}$,and $Ξ_c^{+}π^{-}$ final states through hadronic loop are calculate…
We consider decays of the hidden charm LHCb pentaquarks in the hadrocharmonium and molecular scenarios. In both pictures the LHCb pentaquarks are essentially nonrelativistic bound states. We develop a semirelativistic framework for calculation of the partial decay widths that allows the final particles to be relativistic. Using this approach we calculate the decay widths in the hadrocharmonium and molecular pictures. Molecular hidden charm pentaquarks are constructed as loosely bound states of charmed and anticharmed hadrons. Calculations show that molecular pentaquarks decay predominantly int…
We apply a phenomenological Lagrangian approach to the radiative decay Y(4260) -> X(3872) + gamma. The Y(4260) and X(3872) resonances are considered as composite states containing both molecular hadronic and charmonium components. Having a leading molecular component in the X(3872) and a sole molecular configuration for the Y(4260) results in a prediction compatible with present data.
The beta decay of molecular tritium currently provides the highest sensitivity in laboratory-based neutrino mass measurements. The upcoming Karlsruhe Tritium Neutrino (KATRIN) experiment will improve the sensitivity to 0.2 eV, making a percent-level quantitative understanding of molecular effects essential. The modern theoretical calculations available for neutrino-mass experiments agree with spectroscopic data. Moreover, when neutrino-mass experiments performed in the 1980s with gaseous tritium are re-evaluated using these modern calculations, the extracted neutrino mass-squared values are co…
We study the strong decay channels $P_c^+(4380) \to J/ψp$ and $P_c^+(4450) \to J/ψp$ under $Σ_c \bar{D}^*$ molecular state ansatz. With various spin-parity assignments, the partial decay widths of $J/ψp$ final state are calculated. Our results show that all the $P$ wave $Σ_c {\bar D}^*$ assignments are excluded, while $S$ wave $Σ_c {\bar D}^*$ pictures for $P_c(4380)$ and $P_c(4450)$ are both allowed by present experimental data. The $J^P=3/2^-$ $Σ_c^* \bar{D}$ and $Σ_c^* \bar{D}^*$ molecules are also discussed in the heavy quark limit, and find that the $Σ_c^* \bar{D}$ system for $P_c(4380)$ …
We study the semileptonic $B_s$ and $B$ decays into the $D_{s 0}^{\ast} (2317)$ and $D_{0}^{\ast} (2400)$ resonances, respectively. With the help of a chiral unitarity model in coupled channels we compute the ratio of the decay widths of both processes. Using current values of the width for the $\bar{B}^{0} \to D_{0}^{\ast} (2400)^{+} \barν_{l} l^{-}$ decay we make predictions for the rate of the $\bar{B}_{s}^{0} \to D_{s0}^{\ast} (2317)^{+} \barν_{l} l^{-}$ decay.
Very recently, a new $Ω^{*}$ state was reported by the Belle Collaboration, with its mass of $2012.4 \pm 0.7\ \text{(stat)}\pm 0.6\ \text{(syst)}\ \mathrm{MeV}$, which locates just below the $KΞ^*$ threshold and hence hints to be a possible $KΞ^*$ hadronic molecule. Using the effective Lagrangian approach as the same as our previous works for other possible hadronic molecular states, we investigate the decay behavior of this new $Ω^*$ state within the hadronic molecular picture. The results show that the measured decay width can be reproduced well and its dominant decay channel is predicted to…
We study the $\bar{K} Ξ$ decay mode of the newly observed $Ω(2012)$ assuming that the $Ω(2012)$ is a dynamically generated state with spin-parity $J^P = 3/2^-$ from the coupled channel $S$-wave interactions of $\bar{K}Ξ(1530)$ and $ηΩ$. In addition we also calculate its $KπΞ$ three-body decay mode. It is shown that the so-obtained total decay width is in fair agreement with the experimental data. We compare our results with those of other recent studies and highlight differences among them.
In the present work, we investigate the productions of the molecular states composed of $D^{(*)}_s \bar{D}^{(*)}$ and $D^{(*)}_s \bar{D}^{(*)}_s$ in the $B$ and $B_s$ decays by using an effective Lagrangian approach. The branching ratios in terms of the model parameter $α$ and the binding energy $ΔE$ are estimated. Our estimations indicate that the branching fractions are of the order of $10^{-4}$ and the relative ratios are very weakly dependent on the model parameter $α$ and the binding energy $ΔE$. The predicted ratios are helpful for searching the hidden-charm molecular states with strange…
In the present work, the partial decay widths of $P_{c}(4312)$ to $η_{c} p$ and $J/ψp$ are investigated with the QCD sum rule method under the assumption that $P_{c}(4312)$ is a $\bar{D}Σ_{c}$ molecular state with $J^{P}=\frac{1}{2}^{-}$. In the analysis, the pole residue of $P_{c}(4312)$, one of the input parameters for the calculations of the strong decay constants, is calculated first. With the numerical values of the strong decay constants, the partial decay widths to $η_{c} p$ and $J/ψp$ are estimated to be $Γ(P_{c}(4312)\rightarrow η_{c} p)=5.54^{+0.75}_{-0.5}\mbox{MeV}$ and $Γ(P_{c}(431…
In this article, we tentatively assign the $P_c(4312)$ to be the $\bar{D}Σ_c$ pentaquark molecular state with the spin-parity $J^P={\frac{1}{2}}^-$, and discuss the factorizable and non-factorizable contributions in the two-point QCD sum rules for the $\bar{D}Σ_c$ molecular state in details to prove the reliability of the single pole approximation in the hadronic spectral density. We study its two-body strong decays with the QCD sum rules, special attentions are paid to match the hadron side with the QCD side of the correlation functions to obtain solid duality. We obtain the partial decay wid…
In this work, we have adopted the spin rearrangement scheme in the heavy quark limit and extensively investigated three classes of the radiative decays: $\mathfrak{M}\to (b\bar{b})+γ$, $(b\bar{b})\to \mathfrak{M}+γ$, $ \mathfrak{M} \to \mathfrak{M}^\prime+γ$, corresponding to the electromagnetic transitions between one molecular state and bottomonium, one bottomonium and molecular state, and two molecular states respectively. We also extend the same formalism to study the radiative decays of the molecular states with hidden charm. We have derived some model independent ratios when the initial …
We study the $B_c^- \to π^- J/ψω$ and $B_c^- \to π^- D^* \bar{D}^*$ reactions and show that they are related by the presence of two resonances, the $X(3940)$ and $X(3930)$, that are of molecular nature and couple most strongly to $D^* \bar{D}^*$, but also to $J/ψω$. Because of that, in the $J/ψω$ mass distribution we find a cusp with large strength at the $D^* \bar{D}^*$ threshold and predict the ratio of strengths between the peak of the cusp and the maximum of the $D^* \bar{D}^*$ distribution close to $D^* \bar{D}^*$ threshold, which are distinct features of the molecular nature of these two…
We evaluate the partial decay widths for the semileptonic $Λ_b \to \bar ν_l l Λ_c(2595)$ and $Λ_b \to \bar ν_l l Λ_c(2625)$ decays from the perspective that these two $Λ^*_c$ resonances are dynamically generated from the $DN$ and $D^*N$ interaction with coupled channels. We find that the ratio of the rates obtained for these two reactions is compatible with present experimental data and is very sensitive to the $D^* N$ coupling, which becomes essential to obtain agreement with experiment. Together with the results obtained for the $Λ_b \to π^- Λ^*_c$ reactions, it gives strong support to the m…
Recently, several exotic bosons have been confirmed as multi-quark states, but there are violent disputes about their inner structures, namely if they are molecular states or tetraquarks, or even mixtures of the two structures. It would be interesting to experimentally search for non-strange four-quark states with open charm or bottom which are lighter than $Λ_c$ or $Λ_b$. Reasonable arguments indicate that they are good candidates of pure molecular states $Dπ$ or $Bπ$ because pions are the lightest boson. Both $Bπ$ and $Dπ$ bound states do not decay via strong interaction. The $Bπ$ molecule m…
The LHCb Collaboration announced the observation of three narrow structures consistent with hidden-charm pentaquark states. They are candidates of hadronic molecules formed of a pair of a charmed baryon and an anticharmed meson. Among them, the $P_c(4457)$ mass is consistent with earlier predictions of a $Σ_c\bar D^*$ molecule with $I=1/2$. We point out that if such a picture were true, one would have $\mathcal{B}(P_c(4457)\to J/ψΔ^+)/\mathcal{B}(P_c(4457)\to J/ψp)$ at the level ranging from a few percent to about 30%. Such a large isospin breaking decay ratio is two to three orders of magnitu…
In this talk we show our recent results on the decay widths of $ϕ(2170)$ to final states formed by an anti-Kaon and a Kaonic resonance, in particular, $K(1460)$, $K_1(1270)$ and $K_1(1400)$, considering a molecular description for $ϕ(2170)$. Branching fraction ratios are obtained and compared with the recent results found by the BESIII collaboration, finding compatible results.
The $Ξ_b(6227)$ baryon with the quantum number $J^P=1/2^{-}$ is considered as a molecular state composed of a $Σ_b$ baryon and $\bar{K}$ meson. The partial decay widths of the $Σ_b\bar{K}$ molecular state into $Ξ_bγ$ and $Ξ_b^{'}γ$ final states through hadronic loops are evaluated with the help of the effective Lagrangians. The partial widths for the $Ξ_b(6227)\toγΞ_b$ and $Ξ_b(6227)\toγΞ^{'}_b$ are evaluated to be about 1.50-1.02 KeV and 17.56-24.91 KeV, respectively, which may be accessible for the LHCb. Based on our results we argue that an experimental determination of the radiative decay …
Within a picture of the $f_1(1285)$ being a dynamically generated resonance from the $ K^*\bar K$ interactions, we estimate the rates for the radiative transitions of the $f_1(1285)$ meson to the vector mesons $ρ^0$,$ω$ and $ϕ$. These radiative decays proceed via the kaon loop diagrams. The calculated results are in fair agreement with the experimental measurements. Some predictions can be tested by experiments and their implementation and comparison with these predictions will be valuable to decode the nature of the $f_1(1285)$ state.
Using the general form of the generalized Bethe-Salpeter wave functions for four-quark states describing the meson-meson molecular structure given in our previous work, we obtain the general formulas for the decay widths of molecular states composed of two vector mesons with arbitrary spin and parity into two photons. Then this general formalism is applied to investigate the radiative two-photon decay of the obeserved \emph{X}(3915) state, where this exotic state \emph{X}(3915) is considered as a molecular state consisting of two heavy vector mesons $D^{*0}\bar{D}^{*0}$. The numerical result o…
From the perspective that the $Λ_c(2595)$ and $Λ_c(2625)$ are dynamically generated resonances from the $DN,~D^*N$ interaction and coupled channels, we have evaluated the rates for $Λ_b \to π^- Λ_c(2595)$ and $Λ_b \to π^- Λ_c(2625)$ up to a global unknown factor that allows us to calculate the ratio of rates and compare with experiment, where good agreement is found. Similarly, we can also make predictions for the ratio of rates of the, yet unknown, decays of $Λ_b \to D_s^- Λ_c(2595)$ and $Λ_b \to D_s^- Λ_c(2625)$ and make estimates for their individual branching fractions.
We extend our previous study on the decay behavior of $P_c$ hadronic molecules to their strange and beauty partners. While $P_c(4380)$ and $P_c(4450)$ locate just below the $\bar DΣ_c^*$ and $\bar D^*Σ_c$ thresholds, respectively, their proposed strange partners $N(1875)$ and $N(2080)$ sit just below the $KΣ^*$ and $K^*Σ$ thresholds, respectively. Using the effective Lagrangian approach as the same as for the study of $P_c$ hadronic molecular states and with the couplings determined by the $\mathrm{SU}(3)$ flavor symmetry, the decay patterns of $N(1875)$ and $N(2080)$ are obtained assuming the…
Stimulated by the measurement of the $Jψϕ$ decay model of $Y(4274)$ by the LHCb Collaboration, we consider a possible interpretation of this state as a hadron molecular-a bound state of $D_s$ and $\bar{D}_{s0}(2317)$ mesons. Using effective Lagrangian approach, we calculate the two-body strong decay channels $Y(4274)\to{}J/ψϕ,χ_{c0}η,χ_{c0}η,D^{*}_s\bar{D}_s$, $D\bar{D}^{*}$, $K\bar{K}^{*}$, and $ϕϕ$ through hadronic loops and three-body decays into $π^0{}D_s\bar{D}_s$. In comparison with the LHCb data, our results show that $Y(4274)$ cannot be assigned to be a $D_s\bar{D}_{s0}(2317)$ molecula…
The $P_c(4312)$, $P_c(4440)$, and $P_c(4457)$ observed by the LHCb Collaboration are very likely to be $S$-wave $Σ_c\bar{D}^{(*)}$ molecular candidates due to their near-threshold character. In this work, we study the hidden-charm decay modes of these $P_c$ states, $P_c\to J/ψp(η_cp)$, using a quark interchange model. The decay mechanism for the $P_c\to J/ψp(η_cp)$ processes arises from the quark-quark interactions, where all parameters are determined by the mass spectra of mesons. We present our results in two scenarios. In scenario I, we perform the dynamical calculations and treat the $P_c$…
Investigating the $P$-wave $DK^{*}$ Molecular Interpretation of the $D_{s1}(2700)$ via Its Strong Decays
Key Laboratory of Computational Physics of Sichuan Province, School of Mathematics and Physics, Yibin University（宜宾学院数学与物理学院四川省计算物理重点实验室）；School of Physical Science and Technology, Southwest Jiaotong University（西南交通大学物理科学与技术学院）；School of Physics and Electronic Engineering, Sichuan Normal University（四川师范大学物理电子工程学院）
In this work, we study the radiative and strong decay of $S$-wave $K\bar{K}_1(1400)$ molecular state within the effective Lagrangians approach and find the relation between the $K\bar{K}_1(1400)$ molecular state and the newly observed $η_1(1855)$ state by comparing with the BESIII observation. The prediction indicates that the decay width can reach up to $182.97^{+2.79}_{-3.50}$ MeV, which can be confronted with the experimental data. If the $η_1(1855)$ could be $S$-wave $K\bar{K}_1(1400)$ molecular state, the $K\bar{K}^{*}π$ three-body decay provides the dominant contribution, not the $ηη^{'}…
The rate for complete two-photon annihilation of molecular positronium Ps$_{2}$ is reported. This decay channel involves a four-body collision among the fermions forming Ps$_{2}$, and two photons of 1.022 MeV, each, as the final state. The quantum electrodynamics result for the rate of this process is found to be $Γ_{Ps_{2} \rightarrow γγ}$ = 9.0 $\times 10^{-12}$ s$^{-1}$. This decay channel completes the most comprehensive decay chart for Ps$_{2}$ up to date.
We study the strong decays of the newly observed $Ξ_b(6227)$ assuming that it is a pure $Σ_b\bar{K}$ molecular state. Considering four possible spin-parity assingments $J^P=1/2^{\pm}$ and $3/2^{\pm}$, the partial decay widths of the $Σ_b\bar{K}$ molecular state into $Λ_b\bar{K}$, $Ξ_bπ$, and $Ξ_b^{'}π$ final states through hadronic loops are evaluated with the help of the effective Lagrangians. In comparison with the LHCb data, the spin-party $1/2^-$ assignment is preferred while those of $J^P=1/2^{+}$ and $J^P=3/2^{\pm}$ are disfavored. In addition, we show that the two allowed decay modes $Λ…
We present a mechanism for $Ω_c \to π^+ Ω(2012)$ production through an external emission Cabibbo favored weak decay mode, where the $Ω(2012)$ is dynamically generated from the interaction of $\bar{K}Ξ^*(1530)$, $ηΩ$, with $\bar{K}Ξ$ as the main decay channel. The $Ω(2012)$ decays later to $\bar{K}Ξ$ in this picture, with results compatible with Belle data. The picture has as a consequence that one can evaluate the direct decay $Ω_c^0 \to π^+K^- Ξ^0$ and the decay $Ω_c^0 \to π^+\bar{K} Ξ^*$, $π^+ηΩ$ with direct coupling of $\bar{K}Ξ^*$ and $ηΩ$ to $K^- Ξ^0$. We show that, within uncertainties a…
