arXiv subjects

J. M. Dias

Publications and source records attributed to J. M. Dias.

At least 19 recordsLinked to original sources

arXiv2025

The $D_{s1}(2460) \to D_s π^+ π^- $ decay from a $D_{s1}$ molecular perspective

We conduct a theoretical study of the $ D_{s1}(2460) \to D_s π^+ π^- $ decay from the perspective that the $D_{s1}$ is a molecular state, built mostly from the $D^* K$ and $D_s^* η$ components. The $D^*$ and $D_s^*$ mesons are allowed to decay into two pseudoscalars, with one of them merging with the other pseudoscalar that forms the $D_{s1}$ state, ultimately leading to the $π^+ π^- D_s$ final state. This results in a triangle diagram mechanism where all theoretical ingredients are well-known, leading to a free parameter framework. We evaluate the mass distributions of particle pairs and find good agreement with the experimental distributions of a recent LHCb experiment, providing strong support to the molecular picture of the $D_{s1}(2460)$ state. We also discuss the role played by the scalar mesons $f_0(500)$ and $f_0(980)$, at odds with the interpretation of the experimental analysis.

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arXiv2024

Triangle singularity in the $J/ψ\to ϕπ^+ a_0^-(π^- η),\; ϕπ^- a_0^+(π^+ η)$ decays

We study the $J/ψ\to ϕπ^+ a_0(980)^- (a_0^- \to π^- η)$ decay, evaluating the double mass distribution in terms of the $π^- η$ and $π^+ a^-_0$ invariant masses. We show that the $π^- η$ mass distribution exhibits the typical cusp structure of the $a_0(980)$ seen in recent high statistics experiments, and the $π^+ a^-_0$ spectrum shows clearly a peak around $M_{\rm inv}(π^+ a^-_0)=1420 \,{\rm MeV}$, corresponding to a triangle singularity. When integrating over the two invariant masses we find a branching ratio for this decay of the order of $10^{-5}$, which is easily accessible in present laboratories. We also call attention to the fact that the signal obtained is compatible with a bump experimentally observed in the $ηπ^+π^-$ mass distribution in the $J/ψ\to ϕηπ^+π^-$ decay and encourage further analysis to extract from there the $ϕπ^+ a_0^-$ and $ϕπ^- a_0^+$ decay modes.

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arXiv2021

Unveiling the $K_1(1270)$ double-pole structure in the $\bar{B}\to J/ψρ\bar{K}$ and $\bar{B}\to J/ψ\bar{K}^*π$ decays

By looking at the pseudoscalar-vector meson spectra in the $\bar{B}\to J/ψρ\bar{K}$ and $\bar{B}\to J/ψ\bar{K}^*π$ weak decays, we theoretically investigate the double-pole structure of the $K_1(1270)$ resonance by using the Chiral Unitary approach to account for the final state interactions between the pseudoscalar and vector mesons. The $K_1(1270)$ resonance appears as dynamically generated through these interactions in coupled channels and influence the shape of the invariant mass distributions under consideration. We show how those shapes are affected by the $K_1(1270)$ double-pole structure to confront the results from our model with future experiments that might investigate the $PV$ spectra in these decays.

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arXiv2020

$Ξ_{bb}$ and $Ω_{bbb}$ molecular states

Using the vector-exchange interaction in the local hidden gauge approach, which in the light quark sector generates the chiral Lagrangian, and has produced realistic results for $Ω_c, Ξ_c, Ξ_b$ and the hidden charm pentaquark states, we study the meson-baryon interactions in the coupled channels that lead to the $Ξ_{bb}$ and $Ω_{bbb}$ excited states of the molecular type. We obtain seven states of the $Ξ_{bb}$ type with energies between $10408$ and $10869$ MeV and one $Ω_{bbb}$ state at $15212$ MeV.

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arXiv2019

Molecular $Ξ_{bc}$ states from meson-baryon interaction

We have studied the meson-baryon interaction in coupled channels with the same quantum numbers of $Ξ_{bc}$. The interaction is attractive in some channels and of sufficient intensity to lead to bound states or resonances. We use a model describing the meson-baryon interaction based on an extrapolation of the local hidden gauge approach to the heavy sector, which has been successfully used in predicting $Ω_c$ and hidden charm states. We obtain many states, some of them narrow or with zero width, as a consequence of the interaction, which qualify as molecular states in those channels. The success in related sectors of the picture used should encourage the experimental search for such states.

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arXiv2018

Dynamical Hadrons

In this talk I briefly review the theory of resonances dynamically generated from hadron-hadron scattering, sometimes referred to as "molecules"S. I give some classical examples of meson-meson and meson-baryon systems, as well as a few examples of different approaches to describe the interaction between hadrons. To conclude, I comment on a few recent works that suggest that some of the five new narrow $Ω_c$ states, recently discovered by the LHCb collaboration, can be interpreted as meson-baryon molecules.

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arXiv2018

Doubly charmed $Ξ_{cc}$ molecular states from meson-baryon interaction

Stimulated by the new experimental LHCb findings associated with the $Ω_c$ states, some of which we have described in a previous work as being dynamically generated through meson-baryon interaction, we have extended this approach to make predictions for new $Ξ_{cc}$ molecular states in the $C=2$, $S=0$ and $I=1/2$ sector. These states manifest themselves as poles in the solution of the Bethe-Salpeter equation in coupled channels. The kernels of this equation were obtained using the Lagrangians coming from the hidden local gauge symmetry, where the interactions are dominated by the exchange of light vector mesons. The extension of this approach to the heavy sector stems from the realization that the dominant interaction corresponds to having the heavy quarks as spectators, which implies the preservation of the heavy quark symmetry. As a result, we get several states: two states from the pseudoscalar meson-baryon interaction with $J^P=1/2^-$, and masses around $4080$ and $4090$ MeV, and one at $4150$ MeV for $J^P=3/2^-$. Furthermore, from the vector meson-baryon interaction we get three states degenerate with $J^P=1/2^-$ and $3/2^-$ from $4220$ MeV to $4330$ MeV, and two more states around $4280$ MeV and $4410$ MeV, degenerate with $J^P=1/2^-,\, 3/2^-$ and $5/2^-$.

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arXiv2018

Molecular $Ω_b$ states

Motivated by the recent finding of five $Ω_c$ states by the LHCb collaboration, and the successful reproduction of three of them in a recent approach searching for molecular states of meson-baryon with the quantum numbers of $Ω_c$, we extend these ideas and make predictions for the interaction of meson-baryon in the beauty sector, searching for poles in the scattering matrix that correspond to physical states. We find several $Ω_b$ states: two states with masses 6405~MeV and 6465~MeV for $J^P= \frac{1}{2}^-$; two more states with masses 6427~MeV and 6665~MeV for $\frac{3}{2}^-$; and three states between 6500 and 6820~MeV, degenerate with $J^P=\frac{1}{2}^-,\,\frac{3}{2}^-$, stemming from the interaction of vector-baryon in the beauty sector.

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arXiv2018

$\boldsymbol{Ω_b^- \to (Ξ_c^+ \, K^-) \, π^-}$ and the $\boldsymbol{Ω_c}$ states

We study the weak decay $Ω_b^- \to (Ξ_c^+ \, K^-) \, π^-$, in view of the narrow $Ω_c$ states recently measured by the LHCb collaboration and later confirmed by the Belle collaboration. The $Ω_c(3050)$ and $Ω_c(3090)$ are described as meson-baryon molecular states, using an extension of the local hidden gauge approach in coupled channels. We investigate the $ΞD$, $Ξ_c \bar K$ and $Ξ_c^\prime \bar K$ invariant mass distributions making predictions that could be confronted with future experiments, providing useful information that could help determine the quantum numbers and nature of these states.

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arXiv2018

Disclosing $D^\bar{D}^$ molecular states in the $B_c^- \to π^- J/ψω$ decay

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 resonances.

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arXiv2018

Molecular $Ω_c$ states generated from coupled meson-baryon channels

We have investigated $Ω_c$ states that are dynamically generated from the meson-baryon interaction. We use an extension of the local hidden gauge to obtain the interaction from the exchange of vector mesons. We show that the dominant terms come from the exchange of light vectors, where the heavy quarks are spectators. This has as a consequence that heavy quark symmetry is preserved for the dominant terms in the $(1/m_Q)$ counting, and also that the interaction in this case can be obtained from the $\textrm{SU(3)}$ chiral Lagrangians. We show that for a standard value for the cutoff regulating the loop, we obtain two states with $J^{P}={1/2}^{-}$ and two more with $J^{P}={3/2}^{-}$, three of them in remarkable agreement with three experimental states in mass and width. We also make predictions at higher energies for states of vector-baryon nature.

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arXiv2018

Study of the $DK K$ and $DK \bar{K}$ systems

Using the Fixed Center Approximation to Faddeev equations we have investigated the $DKK$ and $DK\bar{K}$ three-body systems, considering that the $D^*_{s0}(2317)$ acts as the heavy cluster in both cases, generated from the $DK$ interaction in isospin 0. For the $DK\bar{K}$ system we have found evidence of a state with $I(J^P)=1/2(0^-)$ and mass about $2833 - 2858$ MeV, above the threshold of $D^*_{s0}(2317)\bar{K}$. Our results indicate that this state is dominated by a $Df_0(980)$ component, then it could be searched for in the $ππD$ invariant mass. On the other hand, no clear evidence related to a state from the $DKK$ interaction is found.

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arXiv2018

Prediction of new states from $D^{()}B^{()}\bar{B}^{(*)}$ three-body interactions

We study three-body systems composed of $D^{(*)}$, $B^{(*)}$ and $\bar{B}^{(*)}$ in order to look for possible bound states or resonances. In order to solve the three-body problem, we use the fixed center approach for the Faddeev equations considering that the $B^*\bar{B}^*(B\bar{B})$ are clusterized systems, generated dynamically, which interact with a third particle $D(D^*)$ whose mass is much smaller than the two-body bound states forming the cluster. In the $DB^*\bar{B}^*$, $D^*B^*\bar{B}^*$, $DB\bar{B}$ and $D^*B\bar{B}$ systems with $I=1/2$, we found clear bound state peaks with binding energies typically a few tens MeV and more uncertain broad resonant states about ten MeV above the threshold with widths of a few tens MeV.

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arXiv2017

The radiative decay $D^0 \to \bar{K}^{*0} γ$ with vector meson dominance

Motivated by the experimental measurements of $D^0$ radiative decay modes we have proposed a model to study the $D^0\to \bar{K}^{*0}γ$ decay, by establishing a link with $D^0\to \bar{K}^{*0}V$ $(V=ρ^0,\, ω)$ decays through the vector meson dominance hypothesis. In order to do this properly, we have used the Lagrangians from the local hidden gauge symmetry approach to account for $Vγ$ conversion. As a result, we have found the branching ratio $\mathcal{B}[D^0\to \bar{K}^{*0}γ] =(1.55 - 3.44)\times 10^{-4}$, which is in fair agreement with the experimental values reported by Belle and Babar collaborations.

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arXiv2017

On the binding of the $BD\bar{D}$ and $BDD$ systems

We study theoretically the $BD\bar{D}$ and $BDD$ systems to see if they allow for possible bound or resonant states. The three-body interaction is evaluated implementing the Fixed Center Approximation to the Faddeev equations which considers the interaction of a $D$ or $\bar{D}$ particle with the components of a $BD$ cluster, previously proved to form a bound state. We find an $I(J^P)=1/2(0^-)$ bound state for the $BD\bar{D}$ system at an energy around $8925-8985$ MeV within uncertainties, which would correspond to a bottom--hidden-charm meson. In contrast, the $BDD$ system, which would be bottom--double-charm and hence manifestly exotic, we have found hints of a bound state in the energy region $8935-8985$ MeV, but the results are not stable under the uncertainties of the model, and we cannot assure, neither rule out, the possibility of a $BDD$ three-body state.

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arXiv2017

Understanding close-lying exotic charmonia states within QCD sum rules

Motivated by the experimental findings of some new exotic states decaying into channels like $J/ψϕ$, we investigate the formation of resonances/bound states in the $D^*_s\bar D^*_s$ system using QCD sum rules. To do this we start with a current of the type vector times vector and use spin projectors to separate the spin 0, 1 and 2 contributions to the correlation function. We find three states with isospin 0, nearly spin degenerate, with a mass around 4.1 GeV. We have also investigated the decay of these states to $J/ψϕ$ and provide the corresponding partial widths. Such information should be useful for experimental studies in future.

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arXiv2017

Study of the $DKK$ and $DK\bar{K}$ systems

Using the Fixed Center Approximation to Faddeev equations we have investigated the $DKK$ and $DK\bar{K}$ three-body systems, considering that the $DK$ dynamically generates, through its $I=0$ component, the $D^*_{s0}(2317)$ molecule. According to our findings, for $DK\bar{K}$ interaction we have found an evidence of a state $I(J^P)=1/2(0^-)$ just above the $D^*_{s0}(2317)\bar{K}$ threshold and around the $Df_0(980)$ thresholds, with mass about $2833 - 2858$ MeV, made mostly of $Df_0(980)$. On the other hand, no evidence related to a state from the $DKK$ interaction is found. The state found could be seen in the $ππD$ invariant mass.

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arXiv2016

X, Y and Z States

Many new states in the charmonium mass region were recently discovered by BaBar, Belle, CLEO-c, CDF, D0, BESIII, LHCb and CMS Collaborations. We use the QCD Sum Rule approach to study the possible structure of some of these states.

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