arXiv subjects

Elena Santopinto

Publications and source records attributed to Elena Santopinto.

At least 19 recordsLinked to original sources

arXiv2026

Strong decays of the possible $D^{}K$ and $\bar{D}^{}K$ molecules

Inspired by the rich spectrum of structures near the $D^{(*)}K^{(*)}/\bar{D}^{(*)}K^{(*)}$ thresholds, we postulate the existence of $S$-wave $D^{*}K$ and $\bar{D}^{*}K$ molecules, denoted as $T_{c\bar{s}1}^{f}(2460)$ with $I=0$ (corresponding to $D_{s1}(2460)$), $T_{c\bar{s}1}^{a}(2470)$ with $I=1$, $T_{\bar{c}\bar{s}1}^{f}(2460)$ with $I=0$, and $T_{\bar{c}\bar{s}1}^{a}(2470)$ with $I=1$, respectively. Using an effective Lagrangian approach, we investigate the strong decays of these molecular states. Our estimates indicate that the width of $T_{c\bar{s}1}^{a}(2470)$ is roughly three orders of magnitude larger than that of $T_{c\bar{s}1}^{f}(2460)$, while the widths of $T_{\bar{c}\bar{s}1}^{a/f}(2470)$ are of the same orders as that of $T_{c\bar{s}1}^{f}(2460)$. The present study may provide valuable clues for the experimental search for these molecular candidates.

hep-ph↗

arXiv2025

Strong decays of the $DK^\ast$ and $\bar{D}K^{\ast}$ molecular states

Inspired by the abundant structure near the threshold of the $D^{(*)}K^{(*)}/\bar{D}^{(*)}K^{(*)}$, we estimate the strong decay properties of the $T_{c\bar{s}1}^{f/a}$ and $T_{\bar{c}\bar{s}1}^{f/a}$ with $I(J^{P})=0/1(1^{+})$ in $DK^{*}$ and $\bar{D}K^{*}$ molecular scenarios in the present paper. By employing the effective Lagrangian approach, the widths of the processes $T_{c\bar{s}1}^{f}\to D^{*}K, D_{s}^{*}η, DKπ$, $T_{c\bar{s}1}^{a}\to D^{*}K, D_{s}^{*}π, DKπ$, and $T_{\bar{c}\bar{s}1}^{f/a}\to\bar{D}^{*}K, \bar{D}Kπ$ are estimated. Considering the present estimations, we propose to search for $T_{c\bar{s}1}^{f/a}$ states in $D^{*}K$ and $D_{s}^{*}π/D_{s}^{*}η$ mass invariant spectra. Their ratios may serve as an important test of the molecular scenario.

hep-ph↗

arXiv2025

Strange pentaquarks with a hidden heavy quark-antiquark pair

The strange pentaquarks with hidden heavy quark pair ($q^3c\bar c$ and $q^3b \bar b$) are investigated by the coupled-channel quark cluster model. Two types of the $q^3$ color-octet configurations are found to provide the attraction, which makes bound states, sharp resonances, and cusps in the baryon meson scattering. A resonance appears at around 4500 MeV in the strange hidden charm sector. Such structures are more clearly seen in the hidden bottom systems.

hep-ph↗

arXiv2025

Determining the width of $D_{s0}^{*}(2317)$ by using $T_{c\bar{s}0}^{a}(2327)$ in a molecular frame

Motivated by the recent observation of the open-charm tetraquark $T_{c\bar{s}0}^{a}(2327)$ by the LHCb Collaboration, as well as results from Lattice QCD calculations, we consider the $T_{c\bar{s}0}^{a}(2327)$ and the $D_{s0}^{*}(2317)$ as $DK$ molecular states, with $I(J^{P})$ equal to $1(0^{+})$ and $0(0^{+})$, respectively, and we investigate their strong decay behavior in an effective Lagrangian approach. Within the model parameter range, we can reproduce the $T_{c\bar{s}0}^{a}(2327)$ experimental decay width, with the assumption that the $D_{s}^{+}π^{0}$ is the dominant decay channel of the $T_{c\bar{s}0}^{a+}(2327)$. In the same parameter range, we can establish a stringent limitation for the decay width of the $D_{s0}^{*}(2317)$, which is $(63.0-209)~\mathrm{keV}$ being significantly smaller than the PDG upper limit value.

hep-ph↗

arXiv2024

Fully charmed tetraquark production at the LHC experiments

We develop the formalism for production of a fully heavy tetraquark and apply it to the calculation of $pp\to T_{4c}+X$ cross-sections. We demonstrate that the production cross-section of a fully heavy tetraquark, even if it is a diquark-antidiquark cluster, can be obtained in the meson-like basis, for which the spin-color projection technique is well established. Prompted by the recent LHCb, ATLAS and CMS data, we perform a pQCD calculation of ${\cal O}(α_s^5)$ short-distance factors in the dominant channel of gluon fusion, and match these to the four-body $T_{4c}$ wave functions in order to obtain the unpolarized $T_{4c}(0^{++},1^{+-},2^{++})$ cross-sections. The novelty in comparison with the recently published article~\cite{Feng:2023agq} lies in the fact that we predict the absolute values as well as the $dσ/dp_T$ spectra in the kinematic ranges accessible at the ongoing LHC experiments. From the comparison with the signal yield at LHCb we derive the constraints on the $Φ\cdot\text{Br}(J/ψ\,J/ψ)$ (reduced wave function times branching) product for the $T_{4c}$ candidates for $X(6900)$ and observe that $X(6900)$ is compatible with a $2^{++}(2S)$ state.

hep-ph↗

arXiv2022

Rich structure of the hidden-charm pentaquarks near threshold regions

The recent abundant observations of pentaquarks and tetraquarks by high-energy accelerator facilities indicate the realization of the conjecture by Gell-Mann and Zweig, and by De Rujula, Georgi and Glashow [1-3]. We construct a coupled-channel model for the hidden-charm pentaquarks with strangeness whose quark content is $udsc \bar c$, $P_{cs}$, described as $ Λ_c \bar{D}_s^{(*)}, Ξ_c^{('*)} \bar{D}^{(*)}$ molecules coupled to the five-quark states. These molecules are formed by the suitable cooperation of heavy quark and chiral symmetries. We reproduce the experimental mass and quantum numbers $J^P$ of $P_{cs}(4338)$ for which LHCb has just announced the discovery. We make other predictions for new $P_{cs}$ states as molecular states near threshold regions that can be studied by LHCb.

hep-ph↗

arXiv2022

Substructure of Multiquark Hadrons (Snowmass 2021 White Paper)

In recent years there has been a rapidly growing body of experimental evidence for existence of exotic, multiquark hadrons, i.e. mesons which contain additional quarks, beyond the usual quark-antiquark pair and baryons which consist of more than three quarks. In all cases with robust evidence they contain at least one heavy quark Q=c or b, the majority including two heavy quarks. Two key theoretical questions have been triggered by these discoveries: (a) how are quarks organized inside these multiquark states -- as compact objects with all quarks within one confinement volume, interacting via color forces, perhaps with an important role played by diquarks, or as deuteron-like hadronic molecules, bound by light-meson exchange? (b) what other multiquark states should we expect? The two questions are tightly intertwined. Each of the interpretations provides a natural explanation of parts of the data, but neither explains all of the data. It is quite possible that both kinds of structures appear in Nature. It may also be the case that certain states are superpositions of the compact and molecular configurations. This Whitepaper brings together contributions from many leading practitioners in the field, representing a wide spectrum of theoretical interpretations. We discuss the importance of future experimental and phenomenological work, which will lead to better understandingof multiquark phenomena in QCD.

hep-ph↗

arXiv2021

Masses and decay widths of $Ξ_{c/b}$ and $Ξ^\prime_{c/b}$ baryons

In this article, we present a complete classification of the negative parity $Ξ'_{c/b}$ and $Ξ_{c/b}$ $P$-wave states: 7 belonging to the $SU(3)$ flavor sextet and 7 to the flavor anti-triplet, the calculation of the $Ξ'_{c/b}$ and $Ξ_{c/b}$ strong partial decay widths into $^2Σ_c \bar{K}$, $^2Ξ_c^{'} π$, $^2Σ_c \bar{K}$, $^4Ξ_c^{'} π$, $Λ_c^{'} \bar{K}$, $Ξ_c^{} π$ and $Ξ_c^{} η$ channels both within the Elementary Emission Model (EEM) and the $^3P_0$ model, and the calculation of the electromagnetic decay widths for $Ξ'_{c/b}$ and $Ξ_{c/b}$ radiative decays. By means of the equal-spacing mass rule and by the analysis of the strong partial decay widths, we suggest possible assignments for the new LHCb $Ξ_{c}(2923)$, $Ξ_{c}(2939)$, and $Ξ_{c}(2965)$ states, as well as for the $Ξ_{c}$'s previously reported by Belle and BaBar. Our results can be tested by future experiments, at LHCb and Belle, disentangling the remaining missing piece of information, {\it i.e.} the quantum numbers. Finally, a comparison is made between a three-quark and a quark-diquark description of $Ξ_c$ states. Very recently the LHCb collaboration reported the observation of two new $Ξ_b$ states, namely $Ξ_b(6327)^{0}$ and $Ξ_b(6333)$, in $Λ_b^0 K^{-} π^{+}$ channel with a statistical significance larger than nine standard deviations. The experimental masses and widths of these two states are consistent with our mass and width predictions for the doublet of D-wave excitations of the $Ξ_b$ system with $J^{P}_{Ξ_b(6327)^{0}}=\frac{3}{2}^{+}$ and $J^{P}_{Ξ_b(6333)^{0}}=\frac{5}{2}^{+}$.

hep-ph↗

arXiv2021

Triply-heavy tetraquarks in an extended relativized quark model

In this paper, we adopt an extended relativized quark model to investigate the triply-heavy tetrquarks systematically. The mass spectra are obtained by solving the four-body relativized Hamiltonian including the Coulomb potential, confining potential, spin-spin interactions, and relativistic corrections. We find that all of the triply-heavy tetraquarks lie above the corresponding meson-meson thresholds, and thus no stable one exists. In particular, besides the spin-spin interactions, the Coulomb and confining potentials also contribute to the mass splittings in the $cb\bar c \bar q$ and $cb\bar b \bar q$ systems. Moreover, the whole mass spectra for triply heavy tetraquarks show quite similar patterns, which preserve the light flavor SU(3) symmetry and heavy quark symmetry well. Through the fall-apart mechanism, the triply-heavy tetraquarks may easily decay into the heavy quarkonium plus heavy-light mesons, which are good candidates for investigation in future experiments.

hep-ph↗

arXiv2021

Transfer reactions between odd-odd and even-even nuclei by using IBFFM

Spectroscopic Amplitudes (SA) in the Interacting Boson Fermion Fermion Model (IBFFM) are necessary for the computation of $0νββ$ decays but also for cross sections of heavy-ion reactions, in particular, Double Charge Exchange reactions for the NUMEN collaboration, if one does not want to use the closure limit. We present for the first time: i) the formalism and operators to compute in a general case the spectroscopic amplitudes in the scheme IBFFM from an even-even to odd-odd nuclei, in a way suited to be used in reaction code, i.e., extracting the contribution of each orbital; 2) the odd-odd nuclei as described by the old IBFFM are obtained for the first time with the new implementation of Machine Learning (ML) techniques for fitting the parameters, getting a more realistic description. The one body transition densities for $^{116}$Cd $\rightarrow$ $^{116}$In and $^{116}$In $\rightarrow$ $^{116}$Sn are part of the experimental program of the NUMEN experiment, which aims to find constraints on Neutrinoless double beta decay matrix elements.

nucl-th↗

arXiv2020

Heavy Hybrid Decays in a Constituent Gluon Model

A constituent gluon model that is informed by recent lattice field theory is developed. The model is then used to compute hybrid strong decay widths, that can be useful for the GlueX collaboration at Jefferson Lab and the PANDA collaboration at FAIR. Commensurately, forthcoming data from GlueX and PANDA will test the model. Widths tend to be large except for those of the lightest hybrid $S$-wave multiplet. Selection rules, extensions, limitations, and applications are discussed.

hep-ph↗

arXiv2020

$P_c$ pentaquarks with chiral tensor and quark dynamics

We investigate the hidden-charm pentaquarks as superpositions of $Λ_c \bar{D}^{(*)}$ and $Σ_c^{(*)} \bar{D}^{(*)}$ (isospin $I = 1/2$) meson-baryon channels coupled to a $uudc\bar{c}$ compact core by employing an interaction satisfying the heavy quark and chiral symmetries. Our model can consistently explain the masses and decay widths of $P_c^+(4312)$, $P_c^+(4440)$ and $P_c^+(4457)$ with the dominant components of $Σ_c \bar D$ and $Σ_c \bar D^\ast$ with spin parity assignments $J^P = 1/2^{-}, 3/2^{-}$ and $1/2^{-}$, respectively. We analyze basic properties of the $P_c$'s such as masses and decay widths, and find that the mass ordering is dominantly determined by the quark dynamics while the decay widths by the tensor force of the one-pion exchange.

hep-ph↗

arXiv2020

Bottomonium spectrum with a Dirac potential model in the momentum space

We study the bottomonium spectrum using a relativistic potential model in the momentum space. This model is based on a complete one gluon exchange interaction with a momentum dependent screening factor to account for the effects due to virtual pair creation that appear close to the decay thresholds. The overall model does not make use of nonrelativistic approximations. We fit well established bottomonium states below the open charm threshold and predict the rest of the spectrum up to $\approx 11200$ MeV and $J^{PC}=3^{--}$. Uncertainties are treated rigorously and propagated in full to the parameters of the model using a Monte Carlo to identify if which deviations from experimental data can be absorbed into the statistical uncertainties of the models and which can be related to physics beyond the $b\bar{b}$ picture, guiding future research. We get a good description of the spectrum, in particular the Belle measurement of the $η_b(2S)$ state and the $Υ(10860)$ and $χ_b(3P)$ resonances.

hep-ph↗

arXiv2018

Spectroscopy and decays of the fully-heavy tetraquarks

We discuss the possible existence of the fully-heavy tetraquarks. We calculate the ground-state energy of the $bb \bar b \bar b$ bound state, where $b$ stands for the bottom quark, in a nonrelativistic effective field theory framework with one-gluon-exchange (OGE) color Coulomb interaction, and in a relativized diquark model characterized by OGE plus a confining potential. Our analysis advocates the existence of uni-flavor heavy four-quark bound states. The ground state $bb\bar b\bar b$ tetraquark mass is predicted to be $(18.72\pm0.02)$~GeV. Mass inequality relations among the lowest $QQ\bar{Q}\bar{Q}$ state, where $Q\in \{c, b\}$, and the corresponding heavy quarkonia are presented, which give the upper limit on the mass of ground state $QQ\bar{Q}\bar{Q}$. The possible decays of the lowest $bb\bar{b}\bar{b}$ are highlighted, which might provide useful references in the search for them in ongoing LHC experiments, and its width is estimated to be a few tens of MeV.

hep-ph↗

arXiv2018

First radial excitations of heavy quarkonium in a contact interaction

For the flavor-singlet heavy quark systems of quarkonia, we compute the masses of the first radial excitation of mesons in four different channels: pseudo-scalar ($η_{c,b}(2S)$), vector ($ψ(2S),Υ(2S)$), scalar ($χ_{c_0,b_0}(2P)$) and axial vector ($χ_{c_1,b_{1}}(2P)$), as well as the weak decay constants of the $η_{c,b}(2S)$ and $ψ(2S),Υ(2S)$. The framework for this analysis is provided by a symmetry-preserving Schwinger-Dyson equations treatment of a vector$\times$vector contact interaction. The results found for the meson masses are in good agreement experimental data and earlier model calculations based upon Schwinger-Dyson and Bethe-Salpeter equations (BSEs) involving sophisticated interaction kernels.

hep-ph↗

arXiv2018

Spectroscopy of the hidden-charm $[qc][\bar q \bar c]$ and $[sc][\bar s \bar c]$ tetraquarks

We calculate the spectrum of $q\bar q c \bar c$ and $s\bar s c \bar c$ tetraquarks, where $q$, $s$ and $c$ stand for light ($u,d$), strange and charm quarks, respectively, in a relativized diquark model, characterized by one-gluon-exchange (OGE) plus confining potential. In the diquark model, a $q\bar q c \bar c$ ($s\bar s c \bar c$) tetraquark configuration is made up of a heavy-light diquark, $q c$ ($sc$), and anti-diquark, $\bar q \bar c$ ($\bar s \bar c$). According to our results, 13 charmonium-like observed states can be accommodated in the tetraquark picture, both in the hidden-charm ($q\bar q c \bar c$) and hidden-charm hidden-strange ($s\bar s c \bar c$) sectors.

hep-ph↗

arXiv2018

Hidden-charm and bottom meson-baryon molecules coupled with five-quark states

In this paper, we investigate the hidden-charm pentaquarks as $\bar{D}^{(\ast)}Λ_{\rm c}$ and $\bar{D}^{(\ast)}Σ^{(\ast)}_{\rm c}$ molecules coupled to the five-quark states. Furthermore, we extend our calculations to the hidden-bottom sector. The coupling to the five-quark states is treated as the short range potential, where the relative strength for the meson-baryon channels is determined by the structure of the five-quark states. We found that resonant and/or bound states appear in both the charm and bottom sectors. The five-quark state potential turned out to be attractive and, for this reason, it plays an important role to produce these states. In the charm sector, we need the five-quark potential in addition to the pion exchange potential in producing bound and resonant states, whereas, in the bottom sector, the pion exchange interaction is strong enough to produce states. Thus, from this investigation, it emerges that the hidden-bottom pentaquarks are more likely to form than their hidden-charm counterparts; for this reason, we suggest that the experimentalists should look for states in the bottom sector.

hep-ph↗

arXiv2017

Compact pentaquark structures

We study the possibility that at least one of the two pentaquark structures recently reported by LHCb can be described as a compact pentaquark state, and we give predictions for new channels that can be studied by the experimentalists if this hypothesis is correct. We use very general arguments dictated by symmetry considerations, in order to describe the pentaquark states within a group theory approach. A complete classification of all possible states and quantum numbers, that can be useful both to the experimentalists, for new finding, or to theoretical model builders, are given, without the introduction of any particular dynamical model. Some prediction are finally given using a Guersey-Radicati inspired mass formula. We reproduce the mass and the quantum numbers of the lightest pentaquark state reported by LHCb ( 3/2^-), with a parameter free mass formula, fixed on the well established baryons. We predict others pentaquark resonances (giving their masses, and suggesting possible decay channels) which belong to the same multiplet of the lightest one.Finally, we compute the partial decay widths for all the predicted pentaquark resonances.

hep-ph↗