arXiv subjects

Eulogio Oset

Publications and source records attributed to Eulogio Oset.

At least 55 records · Page 3Linked to original sources

arXiv2025

Role of $a_0( 1710)$ in the $D_s^+\toρ^+ϕ,~~ρ^+ω$ decays

We look into the $D_s^+ \to ρ^+ ϕ$ and $D_s^+ \to ρ^+ ω$ weak decays recently measured by the BESIII collaboration, which proceed very differently in a first step of the weak decay. While the first reaction proceeds directly via external emission, the second one does not go via external nor internal emission, what prompted the experimental team to claim that it proceeds via $W-$annihilation. We show in this work that the unexpectedly large rate of the $D_s^+ \to ρ^+ ω$, should it be due to $W-$annihilation, has a different explanation since is it naturally obtained once final state interaction of the $ρ^+ ϕ, ~ρ^+ ω$ and $K^{*+} \bar{K}^{*0}$ channels is taken into consideration. The interaction of these channels produces the $a_0(1710)$ resonance, predicted long ago as a molecular state of these coupled channels, and only recently observed, and it is the presence of this resonance what makes the effect of the final state interaction very important in the weak decays and provides a natural explanation of the experimental decay rates.

hep-ph↗

arXiv2025

On the determination of the $D$ meson width in the nuclear medium with the transparency ratio

We have studied the feasibility of the experimental determination of the width of a $D$ meson in a nuclear medium by using the method of the nuclear transparency. The cross section for inclusive production of a $D^+$ in different nuclei is evaluated, taking care of the $D^+$ absorption in the nucleus, or equivalently, the survival probability of the $D^+$ in its way out of the nucleus from the point of production. We use present values of the in medium width of $D$ mesons and calculate ratios of the cross sections for different nuclei to the $^{12} \text{C} $ nucleus as reference. We find ratios of the order of $0.6$ for heavy nuclei, a large deviation from unity, which indicates that the method proposed is adequate to measure this relevant magnitude, so far only known theoretically.

nucl-th↗

arXiv2024

Testing the molecular nature of the $Ω(2012)$ with the $ψ(3770) \to \barΩ \bar{K} Ξ$ and $ψ(3770) \to \barΩ \bar{K} Ξ^*(1530) (\bar Ω\bar K πΞ)$ reactions

We report on the reactions $ψ(3770)\to \barΩ^+ \bar{K} Ξ$ and $ψ(3770)\to \barΩ^+ \bar{K}Ξ^*(1530)~(Ξ^*(1530)\to πΞ$), and calculate the mass distributions $\frac{{\rm d}Γ}{{\rm d}M_\text{inv}(\bar{K}Ξ)}$ and $\frac{{\rm d}Γ}{{\rm d}M_\text{inv}(\bar{K}Ξ^*)}$, respectively. We obtain clear peaks corresponding to the $Ω(2012)$. From the decay of $ψ(3770)\to \barΩ^+ \bar{K}Ξ^*$, we also get a second, broader, peak around $2035\,\rm MeV$, which comes from the $Ω(2012)$ decay to $\bar{K}Ξ^*$. This second peak is closely tied to the molecular picture of the $Ω(2012)$ with the $\bar{K}Ξ^*(1530)$ and $ηΩ$ components. Its observation would provide a boost to the molecular picture of the $Ω(2012)$.

hep-ph↗

arXiv2024

$P_c(4440)$ and $P_c(4457)$ decay into $\bar{D}Σ_c$ and $\bar{D}Λ_c$ and the spin of the $P_c$ states

We address the issue of the width and spin assignment of the $P_c(4440)$ and $P_c(4457)$ pentaquark states. We calculate the partial decays widths of the particles into $J/ψN$, $\bar{D} Σ_c$ and $\bar{D} Λ_c$ with the first one obtained within a unitary approach with the coupled channels of $J/ψN$ and $\bar{D}^* Σ_c$ with the interaction driven by vector meson exchange, and the last two by means of triangle diagrams involving pion exchange which break the spin degeneracy of the vector meson exchange. The widths obtained depend much on the spin of the particles and we study the possible scenarios for spin assignment, favoring the $1/2^-$ , $3/2^-$ order. We predict values for decays in different channels and show that their determination would allow to decide unambiguously the spin of the states.

hep-ph↗

arXiv2024

How to unravel the nature of the $Σ^*(1430) (1/2^-)$ state from correlation functions

We calculate the correlation functions for the $\bar K^0 p, π^+ Σ^0, π^0 Σ^+, π^+ Λ$, and $ηΣ^+$ states, which in the chiral unitary approach predict an excited $Σ^*(1/2^-)$ state at the $\bar K N$ threshold, recently observed by the Belle Collaboration. Once this is done, we tackle the inverse problem of seeing how much information one can obtain from these correlation functions. With the resampling method, one can determine the scattering parameters of all the channels with relative precision by means of the analysis in a general framework, and find a clear cusplike structure corresponding to the $Σ^*(1/2^-)$ in the different amplitudes at the $\bar{K}N$ threshold.

hep-ph↗

arXiv2024

Study of the exotic three-body $N D^* \bar{K}^*$ system

We have studied the $N D^* \bar{K}^*$ system in the framework of the Fixed Center Approximation to the Faddeev equations, taking the exotic $D^* \bar{K}^* $ system as the cluster and allowing the N to interact with the components of the cluster. Previous studies have determined the existence of three states of spin $0,1,2$ for the $D^* \bar{K}^* $ system, the one of spin $0$ associated to the $X_0(2900)$ state observed by the LHCb collaboration. From this perspective, we find five states with total spin $1/2,3/2,5/2$, with bindings from $10$ to $30$ MeV and widths below $60$ MeV, which could be well identified. We also discuss the decay channels of these states that should help in future experimental searches of these states.

hep-ph↗

arXiv2024

Searching for signals of an exotic $I=1,J^P=2^+$ state of $D^K^$ nature and the structure of the $P_c(4312)$ in the $Λ_b\to Σ_c^{++} D^- K^-$ reaction

This paper investigates the decay process $Λ_b \to Σ_c^{++} D^- K^-$ with the objective of finding a predicted molecular state with isospin $I=1$, $J^P=2^+$ of $D^* K^*$ nature, plus finding support for the $P_c(4312)$ state as made out of $Σ_c \bar{D}$. The mass distribution of the $D^- K^-$ system shows distinct features as a consequence of the existing of this $2^+$ state, while the $Σ_c \bar{D}$ distribution exhibits a significant peak near the threshold, much bigger than phase space expectations, which is linked to our assumed $Σ_c \bar{D}$ nature of the $P_c(4312)$ state below the $Σ_c \bar{D}$ threshold. The reaction has been measured at LHCb Collaboration, but only the branching ratio is measured. The present study shows that much valuable information can be obtained about the predicted $2^+$ $T_{c\bar{s}}(2834)$ of $D^* K^*$ nature and the $P_c(4312)$ states from the measurements of the mass distributions in this reaction, which will be accessible in the planned updates of LHCb.

hep-ph↗

arXiv2024

The $Λ_c^+\toηπ^+Λ$ reaction and the $Λa_0^+(980)$ and $π^+Λ(1670)$ contributions

We study from the theoretical point of view the $Λ_c^+\to π^+ ηΛ$ reaction, recently measured by the Belle and BESIII Collaborations, where clear signals are observed for $a_0(980)$, $Λ(1670)$, and $Σ(1385)$ excitation. By considering the $a_0(980)$ and $Λ(1670)$ as dynamically generated resonances from the meson meson and meson baryon interaction, respectively, we are able to determine their relative production strength in the reaction, which is also tied to the strength of the $π^+ ηΛ$ tree level contribution. We observe that this latter strength is very big and there are large destructive interferences between the tree level and the rescattering terms where the $a_0(980)$ and $Λ(1670)$ are generated. The $Σ(1385)$ contribution is included by means of a free parameter, the only one of the theory, up to a global normalization, when one considers only external emission, and we observe that the spin flip part of this term, usually ignored in theoretical and experimental works, plays an important role determining the shape of the mass distributions. Internal emission is also considered and it is found to play a minor role.

hep-ph↗

arXiv2024

Photoproduction of the $ Λ(1800) $

We have carried out a study of the $γ~ p \rightarrow p K^{+} K^{*-} (K^{*-} \rightarrow K^{-} π^{0}) $, $ γ~p \rightarrow p K^{+} K^{*-} ( K^{*-} \rightarrow \bar{K}^{0} π^{-} )$ and $ γ~p \rightarrow K^{+} K^{-}p$ reactions, producing the $K^+ Λ(1800)$ final state, from the perspective that the $Λ(1800)$ resonance is dynamically generated from the interaction of $\bar{K}^* N$ with its coupled vector-baryon channels, in complete analogy to the $Λ(1405)$ generated from the interaction of $\bar{K} N$ and its coupled pseudoscalar-baryon channels. The two reactions are complementary and their mass distributions are tied to the particular nature of this resonance in that framework. We provide much information on the shapes and strength of the invariant mass distributions of these reactions, and the energy dependence of the cross sections, that when contrasted with future experiments should shed valuable light on the nature of this resonance and its analogy to the $Λ(1405)$.

hep-ph↗

arXiv2024

Determination of the $K^{+}\bar{K}^{0}$ scattering length and effective range and its relation to the $a_{0}^{+}(980)$ from the $χ_{c1}\toπ^{+}π^{-}η$ reaction

We analyze the clean cusp, seen in the $ηπ$ mass distribution with high precision of the $χ_{c1} \to ηπ^+ π^-$ reaction in the BESIII experiment, with the aim of making a precise determination of the scattering length $a$ and effective range $r_0$ of $K^+ \bar{K}^{0}$. For that, we follow a previous theoretical work that gave a good reproduction of these data using the chiral unitary approach for the meson-meson interaction, and allow some flexibility in the input to carry a better fit to the data. The important task of determining the uncertainties in the scattering parameters is done using the resampling method and an accuracy in $a$ and $r_0$ is obtained better than $20\%$. The effective range is determined for the first time with this analysis.

hep-ph↗

arXiv2024

Possible signal of an exotic $I=1$, $J=2$ state in the $B \to D^{*-}D^+K^+$ reaction

We study the \proc reaction, showing that a peak in the \dk mass distribution around 2834 MeV reported by LHCb could be associated with a theoretical exotic state with that mass, a width of 19 MeV and $J^P=2^+$, stemming from the interaction of the $D^{*+}K^{*+}$ and $D^{*+}_s ρ^+$ channels, which is a partner of the $0^+$ $T_{c\bar{s}}(2900)$. We show that the data is compatible with this assumption, but also see that the mass distribution itself cannot discriminate between the spins $J=0$, $1$, $2$ of the state. Then we evaluate the momenta of the angular mass distribution and show that they are very different for each of the spin assumptions, and that the momenta coming from interference terms have larger strength at the resonant energy than the peaks seen in the angular integrated mass distribution. We make a call for the experimental determination of these magnitudes, which has already been used by the LHCb in related decay reactions.

hep-ph↗

arXiv2024

Precise determination of the $ηΛ$ scattering length and effective range and relationship to the $Λ(1670)$ resonance

We use the Belle data on the $K^- p$ mass distribution of the $Λ_c^+ \to p K^- π^+$ reaction near the $ηΛ$ threshold to determine the $ηΛ$ scattering length and effective range. We show that from these data alone we can determine the value of $a$ with better precision than so far determined, and the value of $r_0$ for the first time. The addition of the $K^- p \to ηΛ$ data allows us to improve the precision of these magnitudes, with errors smaller than $15\%$. We also determine with high precision the pole position of the $Λ(1670)$.

hep-ph↗

arXiv2024

Pentaquark molecular states with hidden bottom and double strangeness

We investigate the meson-baryon interaction in coupled channels with the quantum numbers of the pentaquarks $P_{bss}$ and $P_{bsss}$. The interaction is derived from an extension of the local hidden gauge approach to the heavy quark sector, which has demonstrated accurate results compared to experiments involving $Ω_{b}$, $Ξ_{b}$ states, and pentaquarks $P_{c}$ and $P_{cs}$. In our study, we identify several molecular states with small decay widths within the chosen set of coupled channels. The spin-parity ($J^P$) of these states is as follows: $J^P={\frac{1}{2}}^-$ for pseudoscalar-baryon (${\frac{1}{2}}^+$) coupled channels, $J^P={\frac{3}{2}}^-$ for pseudoscalar-baryon (${\frac{3}{2}}^+$) coupled channels, $J^P={\frac{1}{2}}^-$ and ${\frac{3}{2}}^-$ for vector-baryon (${\frac{1}{2}}^+$) coupled channels, and $J^P={\frac{1}{2}}^-$, ${\frac{3}{2}}^-$, ${\frac{5}{2}}^-$ for vector-baryon (${\frac{3}{2}}^+$) coupled channels. We search for the poles of these states and evaluate their couplings to the different channels.

hep-ph↗

arXiv2024

Study of possible $DND^*$ bound states

We start from a recently favored picture in which the $Λ_c(2940)$ and $Λ_c(2910)$ correspond mostly to $ND^*$ bound states with $J^P = 1/2^-,\, 3/2^-$ and then add a $D$ as a third particle, looking for the possible binding of the $DND^*$ three body system within the framework of the Fixed Center Approximation. We find that the system is bound with respect to the corresponding $Λ_c^* D$ threshold with a binding of about $60$ MeV and a width of about $90$ MeV. Alternatively we assume a cluster of $ND$ and a $D^*$ meson interacting with the cluster and we find similar results. The observation of these states of $J^P = 1/2^+,\, 3/2^+$ would provide new and valuable information concerning the $DN$ and $D^* N$ interaction, an issue of current debate.

hep-ph↗

arXiv2024

The $Ω_c \to π^+ \, (π^0,\, η)\, πΞ^*$ reactions and the two $Ξ(1820)$ states

We have studied the $Ω_c \to π^+ (π^0, η) πΞ^*$ decays, where the final $πΞ^*$ comes from the decay of two resonances around the nominal $Ξ(1820)$, which are generated from the interaction of coupled channels made of a pseudoscalar and a baryon of the decuplet. The $πΞ^*$ mass distributions obtained in the six different reactions studied are quite different and we single out four of them, which are free of a tree level contribution, showing more clearly the effect of the resonances. The lower mass resonance is clearly seen as a sharp peak, but the higher mass resonance manifests itself through an interference with the lower one that leads to a dip in the mass distribution around $1850 \, {\rm MeV}$. Such a feature is similar to the dip observed in the $s$-wave $ππ$ cross section around the $980 \, {\rm MeV}$ coming from the interference of the $f_0(500)$ and $f_0(980)$ resonances. Its observation in coming upgrades of present facilities will shed light on the existence of these two resonances and their nature.

hep-ph↗

arXiv2024

$\bar{B}_s^0 \to D_{s1}(2460)^+ K^-, D_{s1}(2536)^+ K^-$ and the nature of the two $D_{s1}$ resonance

Starting from the molecular picture for the $D_{s1}(2460)$ and $D_{s1}(2536)$ resonances, which are dynamically generated by the interaction of coupled channels, the most important of which are the $D^*K$ for the $D_{s1}(2460)$ and $DK^*$ for the $D_{s1}(2536)$, we evaluate the ratio of decay widths for the $\bar{B}_s^0 \to D_{s1}(2460)^+ K^-$ and $\bar{B}_s^0 \to D_{s1}(2536)^+ K^-$ decays, the latter of which has been recently investigated by the LHCb collaboration, and we obtain a ratio of the order of unity. The present results should provide an incentive for the related decay into the $D_{s1}(2460)$ resonance to be performed, which would provide valuable information on the nature of these two resonances.

hep-ph↗

arXiv2024

Correlation function and the inverse problem in the $BD$ interaction

We study the correlation functions of the $B^0 D^+, B^+ D^0$ system, which develops a bound state of approximately $40$ MeV, using inputs consistent with the $T_{cc}(3875)$ state. Then we address the inverse problem starting from these correlation functions to determine the scattering observables related to the system, including the existence of the bound state and its molecular nature. The important output of the approach is the uncertainty with which these observables can be obtained, considering errors in the $B^0 D^+, B^+ D^0$ correlation functions typical of current values in present correlation functions. We find that it is possible to obtain scattering lengths and effective ranges with relative high precision and the existence of a bound state. Although the pole position is obtained with errors of the order of $50 \%$ of the binding energy, the molecular probability of the state is obtained with a very small error of the order of $6\%$. All these findings can serve as motivation to perform such measurements in future runs of high energy hadron collisions.

hep-ph↗

arXiv2024

$\bar B^0 \to \bar K^{() \,0} X$, $B^- \to K^{() \, -} X$, $\bar B_s^0 \to η(η', ϕ) X$ from the $X(3872)$ molecular perspective

We study the decays $\bar B^0 \to \bar K^0 \, X$, $B^- \to K^- \, X$, $\bar B^0_s \to η(η')\, X$, $\bar B^0 \to \bar K^{*0} \, X$, $B^- \to K^{*-} \, X$ , $\bar B_s^0 \to ϕ\, X$, with $X \equiv X(3872)$, from the perspective of the $X(3872)$ being a molecular state made from the interaction of the $D^{*+} D^-, D^{*0} \bar D^0$ and $c.c.$ components. We consider both the external and internal emission decay mechanisms and find an explanation for the $\bar K^0 \, X$ and $K^- \, X$ production rates, based on the mass difference of the charged and neutral $D^* \bar D$ components. We also find that the internal and external emission mechanisms add constructively in the $\bar B^0 \to \bar K^0 \, X$, $B^- \to K^- \, X$ reactions, while they add destructively in the case of $\bar B^0 \to \bar K^{*0} \, X$, $B^- \to K^{*-} \, X$ reactions. This feature explains the decay widths of the present measurements and allows us to make predictions for the unmeasured modes of $\bar B^0_s \to η(η')\, X(3872)$ and $B^- \to K^{*-} \, X(3872)$. The future measurement of these decay modes will help us get a better perspective on the nature of the $X(3872)$ and the mechanisms present in production reactions of that state.

hep-ph↗