We conduct a study of the interaction of the $\bar K Ξ^*$, $ηΩ$($s$-wave) and $\bar K Ξ$($d$-wave) channels within a coupled channel unitary approach where the transition potential between the $\bar K Ξ^*$ and $ηΩ$ channels is obtained from chiral Lagrangians. The transition potential between $\bar K Ξ^*$, $ηΩ$ and $\bar K Ξ$ is taken in terms of free parameters, which together with a cut off to regularize the meson-baryon loops are fitted to the $Ω(2012)$ data. We find that all data including the recent Belle experiment on $Γ_{Ω^* \to π\bar K Ξ}/ Γ_{Ω^* \to \bar K Ξ}$, are compatible with the molecular picture stemming from meson baryon interaction of these channels.
Based upon the color-dipole picture, we provide closed analytic expressions for the longitudinal and the transverse photoabsorption cross sections at low values of the Bjorken variable of x<0.1. We compare with the experimental data for the longitudinal-to-transverse ratio of the (virtual) photoabsorption cross section and with our previous fit to the experimental data for the total photoabsorption cross section. Scaling in terms of the low-x scaling variable eta(W^2,Q^2) is analyzed in terms of the reduced cross section of deep inelastic scattering.
We perform an adjust to the most recent structure function data, considering the QCD dipole picture applied to ep scattering. The structure function F2 at small x and intermediate Q2 can be described by the model containing an economical number of free-parameters, which encodes the hard Pomeron physics. The longitudinal structure function and the gluon distribution are predicted without further adjustments. The data description is effective, whereas a resummed next-to-leading level analysis is deserved.
We analyze excited baryon properties via a 1/N_c expansion from two perspectives: as resonances in meson-nucleon scattering, and as single-quark excitations in the context of a simple quark model. For both types of analysis one can derive novel patterns of degeneracy that emerge as N_c --> \infty, and that are shown to be compatible with one another. This helps justify the single-quark excitation picture and may give some insight into its successes. We also find that in the large N_c limit one of the S_{11} baryons does not couple to the pi-N channel but couples to the eta-N channel. This is e…
An extensive phenomenological study of the Drell-Yan (DY) process in $pp$ collisions at various energies is performed in the color dipole framework. Besides previously studied $γ^*$ production we have also included the $Z^0$ contribution relevant at large dilepton invariant masses. We investigate the DY cross section differential in invariant mass, rapidity and transverse momentum of the dilepton pair in $pp$ collisions at RHIC and LHC. We consider three different phenomenological models for the dipole cross section and found a reasonable agreement with the available data. As a further test of…
We discuss the compatibility between the quark-shell picture and the meson-nucleon scattering picture in large $N_c$ QCD for mixed symmetric $\ell$ = 1 states previously analyzed by using a simple Hamiltonian including operators up to order $\mathcal{O}(N^0_c)$ defined in the standard ground state symmetric core + excited quark procedure. Here we introduce a Hamiltonian of order $\mathcal{O}(N^0_c)$ defined in a new approach where the separation of the system into two parts is not required. Three degenerate sets of states (towers) with the same quantum numbers as in the scattering picture and …
We calculate the probabilities of various charmed meson molecules for $X(4260)$ under the framework of ${}^3P_0$ model. The results indicate that even though heavy quark spin symmetry forbids $S$ wave coupling of $D_1\bar{D}$ to the ${}^3S_1$ charmonia ($ψ(nS)$), the $D$ wave coupling is allowed and not negligible. Under this symmetry, the $D_1\bar{D}$ can couple to ${}^3D_1$ charmonia ($ψ(nD)$) via both $S$ and $D$ wave, and the overall coupling is around three times larger than that of $ψ(nS)$. The $X(4260)$ cannot be a pure molecule but a mixture of a charmonium and various charmed meson co…
In this talk, we review our recent work about the dynamical studies of $Z^+(4430)$ and X(3872). $Z^+(4430)$ can not be explained as a $D_1'D^*$ or $D_1D^*$ molecular state only considering one pion exchange potential without the cutoff, which needs to be confirmed by introducing sigma exchange potential and adding the cutoff in the effective potential. One also excludes the possibility of X(3872) as a $DD^*$ molecular state by one pion and one sigma exchanges with the cutoff. Fortunately there exists an S-wave $BB^*$ bound state with $J^{PC}=1^{++}$. we suggest future experiment to search this…
We present an updated discussion of $K\raπ\bar{l} l$ decays in a combined framework of chiral perturbation theory and Large--$N_c$ QCD, which assumes the dominance of a minimal narrow resonance structure in the invariant mass dependence of the $ \bar{l} l$ pair. The proposed picture reproduces very well, both the experimental $K^+\raπ^+ e^+ e^-$ decay rate and the invariant $e^+ e^-$ mass spectrum. The predicted Br$(K_S\raπ^0 e^+ e^-)$ is, within errors, consistent with the recently reported result from the NA48 collaboration. Predictions for the $K\raπμ^{+}μ^{-}$ modes are also obtained. We f…
In this talk, we firstly overview the experimental status of $\bar{N}_X(1625)$, which is an enhancement structure observed in $K^{-}\barΛ$ invariant mass spectrum of $J/ψ\to pK^{-}\barΛ$ process. Then we present the result of the decay of $\bar{N}_X(1625)$ under the two molecular assumptions, i.e. S-wave $\barΛK^-$ and S-wave $\barΣ^0K^-$ molecular states. Several experimental suggestions for $\bar{N}_X(1625)$ are proposed.
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 investigated the bound state problem of the S wave charged $D_1 \bar{D}^*$ ($D_1' \bar{D}^*$) system in a chiral quark model by solving the resonating group method equation. Our preliminary study does not favor the molecular assumption of $Z^+(4430)$. On the contrary, if $Z^+(4430)$ is really a molecule, its partner with opposite $G$-parity should also exist and probably may be found in the $π^+η_c(2S)$, $J/ψπ^+π^0$, or $ψ'π^+π^0$ channel. For the bottom systems, we found the existence of both $I^G$=$1^+$ and $I^G$=$1^-$ $B_1 \bar{B}^*$ ($B_1' \bar{B}^*$) molecules is possible.
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…
To better understand the nature and internal structure of the exotic states discovered by many collaborations, more information on their electromagnetic properties and their strong and weak interactions with other hadrons is needed. The residue or current coupling constant of these states together with their mass are the main inputs in determinations of such properties. We perform QCD sum rules analyses on the hidden-charm pentaquark states with spin-parities $ J^{P}= \frac{3}{2}^{\pm}$ and $ J^{P}= \frac{5}{2}^{\pm}$ to calculate their residue and mass. In the calculations, we adopt a molecul…
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 …
The $f_0(1710)$ was previously proposed to be dynamically generated state by interactions between vector mesons. We extend the study of $f_0(1710)$ by including its coupling to channels of pseudoscalar mesons within coupled-channel approach. The channels involved are $K^*\bar{K}^*,ρρ,ωω,ϕϕ, ωϕ,ππ,K\bar{K},ηη$. We show that the pole assigned to $f_0(1710)$ does not change much. Then we calculate the partial decay widths of $f_0(1710) \to K^*\bar{K}^* \to ππ,K\bar{K},ηη$ as the coupled channel dynamically generated state as well as assuming it to be pure $K^*\bar{K}^*$ molecule. In both cases th…
We calculate the magnetic dipole moment of the newly observed charged hidden-charmed open strange $ Z_{cs}(3985)^- $ state, recently observed by BESIII Collaboration. Based on the information provided by the experiment and theoretical studies followed the observation, we assign the quantum numbers $ J^{P} = 1^{+}$ and the quark composition $ c \bar c s\bar u $ to this state and estimate the magnetic dipole moment of this resonance in both the compact diquark-antidiquark and molecular pictures. We apply the light cone QCD formalism and use the distribution amplitudes of the on-shell photon with…
We investigate the exotic $ΩΩ$ dibaryon states with $J^P=0^+$ and $2^+$ in a molecular picture. We construct the scalar and tensor $Ω$$Ω$ molecular interpolating currents and calculate their masses within the method of QCD sum rules. Our results indicate that the mass of the scalar dibaryon state is $m_{ΩΩ, \, 0^+}=(3.33\pm0.22) \,\unit$, which is about $15 \,\mathrm{MeV}$ below the $2m_Ω$ threshold. This result suggests the existence of a loosely bound molecular state of the $J^P=0^+$ scalar $ΩΩ$ dibaryon with a small binding energy around 15 MeV. The mass of the tensor dibaryon is predicted …
The one-boson exchange potential model for $Λ_cN$ is constructed and the possibility of $Λ_cN$ bound states is examined. We consider an effective Lagrangian for the charmed baryons, $Λ_c$, $Σ_c$, and $Σ_c^*$, reflecting the heavy quark symmetry, chiral symmetry, and hidden local symmetry. We determine the coupling constants using various methods. With the derived nonrelativistic potentials, we study the bound state problem of the $Λ_cN$ system and relevant coupled channel effects. It is found that molecular bound states of $Λ_cN$ are plausible, for which the channel couplings of $Σ_cN$ and $Σ_…
From a picture of the X(3872) where the resonance is a bound state of $\bar{D}D^*-c.c.$, we evaluate the decay width into the $J/ψγ$ channel, which is sensitive to the internal structure of this state. For this purpose we evaluate the loops through which the X(3872) decays into its components, and the $J/ψ$ and the photon are radiated from these components. We use the local hidden gauge approach extrapolated to SU(4) with a particular SU(4) breaking. The radiative decay involves anomalous couplings and we obtain acceptable values which are compared to experiments and results of other calculati…
Inspired by the newly observed $X_{0}(2900)$ and $X_1(2900)$ at LHCb, the $K^*\bar{D}^*$ and $K\bar{D}_1$ interactions are studied in the quasipotential Bethe-Salpeter equation approach combined with the one-boson-exchange model. The bound and virtual states from the interactions are searched for as the poles in the complex energy plane of scattering amplitude. A bound state with $I(J^P)=0(0^+)$ and a virtual state with $0(1^-)$ are produced from the $K^*\bar{D}^*$ interaction and $K\bar{D}_1$ interaction, and can be related to the $X_{0}(2900)$ and $X_1(2900)$ observed at LHCb, respectively. …
The hidden-charmed pentaquark $P_c(4450)$ and the charmonium-like state $Y(4274)$ are investigated as a $\bar{D}^*Σ_c$ and a $D_s\bar{D}_{s0}(2317)$ molecular state, respectively. The spin parities of these two states cannot be well understood if only S-wave $\bar{D}^*Σ_c$ and $D_s\bar{D}_{s0}(2317)$ interactions are considered. In this work, the interactions are studied in a quasipotential Bethe-Salpeter equation approach with a partial wave decomposition on spin parity $J^P$, and the contributions of different partial waves are studied in a two-channel scattering model including a generating…
Starting from 2003, a large number of the so-called exotic hadrons, such as $X(3872)$ and $D_{s0}^*(2317)$, were discovered experimentally. Since then, understanding the nature of these states has been a central issue both theoretically and experimentally. As many of these states are located close to two hadron thresholds, they are believed to be molecular states or at least contain large molecular components. We argue that if they are indeed molecular states, in the way that the deuteron is a bound state of proton and neutron, then molecular states of three or more hadrons are likely, in the …
Considering two molecular state assumptions, i.e. S-wave $\barΛ-K^-$ and S-wave $\barΣ^0-K^-$ molecular states, we study the possible decays of $\bar N_X(1625)$ that include $\bar N_X(1625)\to K^{-}\barΛ, π^{0}\bar{p}, η\bar{p}, π^{-}\bar{n}$. Our results indicate: (1) if $\bar N_{X}(1625)$ is $\barΛ-K^-$ molecular state, $K^{-}\barΛ$ is the main decay modes of $\bar N_{X}(1625)$, and the branching ratios of the rest decay modes are tiny; (2) if $\bar N_{X}(1625)$ is $\barΣ^0-K^-$ molecular state, the branching ratio of $\bar N_{X}(1625)\to K^{-}\barΛ$ is one or two order smaller than that of …
The possibility of the Y(4260) being the molecular state of $D\bar D_1(2420)+\mathrm{c.c.}$ is investigated in the one boson exchange model. It turns out that the potential of $J^{PC}=1^{--}$ state formed by $D\bar D_1(2420)+\mathrm{c.c.}$ is attractive and strong enough to bind them together when the momentum cutoff $Λ\gtrsim 1.4$ GeV. To produce the Y(4260) with correct binding energy, we need $Λ\approx 2.1$ GeV. Besides, $D\bar D_1(2420)+\mathrm{c.c.}$ can also form a state with exotic quantum numbers, $J^{PC}=1^{-+}$, and its potential similar with that of the $J^{PC}=1^{--}$ state. Theref…
We recall the predictions made ten years ago about a bound state of $J^P=0^+$ in $I=0 $ of the $D^* \bar{K}^*$ system, which is manifestly exotic, and we associate it to the $X_0(2866)$ state reported in the recent LHCb experiment. Fine tuning the parameters to reproduce exactly the mass and width of the $X_0(2866)$ state, we report two more states stemming from the same interaction, one with $1^+$ and the other with $2^+$. For reasons of parity, the $1^+$ state cannot be observed in $D\bar{K}$ decay, and we suggest to observe it in the $D^*\bar{K}$ spectrum. On the other hand, the $2^+$ state…
In this study, we use the molecular and diquark-antidiquark tetraquark pictures to investigate magnetic and quadrupole moments of the $B_c$-like ground state tetraquarks with the QCD light-cone sum rules with quantum numbers $J^P = 1^+$. In the numerical analysis, to obtain the magnetic and quadrupole moments of $B_c$-like tetraquark states molecular and diquark-antidiquark forms of interpolating currents, and photon distribution amplitudes have been used. The magnetic moments are acquired as $ μ_{Z_{uc \bar u \bar b}}^{Mol}=1.18^{+0.52}_{-0.40}~μ_N$, $μ_{Z_{uc \bar u \bar b}}^{Di}=3.05^{+1.19…
Heavy-quark symmetry as applied to heavy hadron systems implies that their interactions are independent of their heavy-quark spin (heavy-quark spin symmetry) and heavy flavour contents (heavy flavour symmetry). In the molecular hypothesis the $X(3872)$ resonance is a $1^{++}$ $D^*\bar{D}$ bound state. If this is the case, the application of heavy-quark symmetry to a molecular $X(3872)$ suggests the existence of a series of partner states, the most obvious of which is a possible $2^{++}$ $D^*\bar{D}^*$ bound state for which the two-body potential is identical to that of the $1^{++}$ $D^*\bar{D}…
We revisit two-color, two-flavor chiral perturbation theory at finite isospin and baryon density. We investigate the phase diagram obtained varying the isospin and the baryon chemical potentials, focusing on the phase transition occurring when the two chemical potentials are equal and exceed the pion mass (which is degenerate with the diquark mass). In this case, there is a change in the order parameter of the theory that does not lend itself to the standard picture of first order transitions. We explore this phase transition both within a Ginzburg-Landau framework valid in a limited parameter…
The three pentaquark states, $P_{c}(4312)$, $P_{c}(4440)$, and $P_{c}(4457)$, discovered by the LHCb Collaboration in 2019, can be nicely arranged into a multiplet of $\bar{D}^{(\ast)}Σ_{c}^{(\ast)}$ of seven molecules dictated by heavy quark spin symmetry. In this work we employ the effective Lagrangian approach to investigate the two decay modes of $P_{c}(4457)$, $P_{c}(4457) \to P_{c}(4312) π$ and $P_{c}(4457) \to P_{c}(4312) γ$, via the triangle mechanism, assuming that $P_{c}(4457)$ and $P_{c}(4312)$ are $\bar{D}^{\ast}Σ_{c}$ and $\bar{D}Σ_{c}$ bound states but the spin of $P_{c}(4457)$ c…
The $X_0(2900)$ observed by the LHCb Collaboration recently in the $D^-K^+$ invariant mass of the $B^+\to D^+D^-K^+$ process is the first exotic candidate with four different flavors, which opens a new era for the hadron community. Under the assumption that the $X_0(2900)$ is a $I(J^P)=0(0^+)$ $\bar{D}^*K^*$ hadronic molecule, we extract the whole heavy-quark symmetry multiplet formed by the $\left(\bar{D},\bar{D}^*\right)$ doublet and the $K^*$ meson. For the bound state case, there would be two additional $I(J^P)=0(1^+)$ hadronic molecules associated with the $\bar{D}K^*$ and $\bar{D}^*K^*$ …
The neutrino long wavelength (just-so) oscillation is revisited as a solution to the solar neutrino problem. We consider just-so scenario in various cases: in the framework of the solar models with relaxed prediction of the boron neutrino flux, as well as in the presence of the non-standard weak range interactions between neutrino and matter constituents. We show that the fit of the experimental data in the just-so scenario is not very good for any reasonable value of the $^8B$ neutrino flux, but it substantially improves if the non-standard $τ$-neutrino--electron interaction is included. Thes…
There are different assumptions on the substructure of the pentaquarks $P_c(4380)$ and $P_c(4450)$, newly founded in $J/ψN $ invariant mass by the LHCb collaboration, giving consistent mass results with the experimental observations. The experimental data and recent theoretical studies on their mass suggest interpretation of these states as spin-3/2 negative-parity and spin-5/2 positive-parity pentaquarks, respectively. There may exist opposite-parity states corresponding to these particles, as well. Despite a lot of studies, however, the nature and internal organization of these pentaquarks i…
We present a dynamical approach for description of the multi-quark states that is based on an effective interaction Lagrangian describing the coupling of hadrons to their constituent quarks. First, we explore the consequences of treating the $X(3872)$ meson as a tetraquark bound state. We calculate the decay widths of the observed channels and conclude that for reasonable values of the size parameter of the $X(3872)$ one finds consistency with the available experimental data. Then we have critically checked the tetraquark picture for the $Z_c(3900)$ state by analyzing its strong decays. We fou…
