arXiv subjects

Jorge Segovia

Publications and source records attributed to Jorge Segovia.

At least 19 recordsLinked to original sources

arXiv2026

Fully strange tetra- and penta-quarks in a chiral quark model

Motivated by the recently reported resonant structure $X(2300)$, a strong candidate for a fully strange tetraquark with positive parity, we perform a systematic study of fully strange tetra- and penta-quark systems within a chiral quark model. Low-lying $S$-wave configurations of the $ss\bar s\bar s$ and $ssss\bar s$ systems are investigated using the Gaussian Expansion Method (GEM) combined with the Complex Scaling Method (CSM), which allows for a unified treatment of bound, resonant, and scattering states. For tetraquarks, all possible configurations: meson-meson, diquark-antidiquark, and K-type structures, with complete color bases, are incorporated, while baryon-meson and diquark-diquark-antiquark configurations are considered for pentaquarks. Several weakly bound states and narrow resonances are identified in both sectors. In particular, a compact fully strange tetraquark with $J^P=1^+$ is found near $2.3\,\text{GeV}$, providing a natural interpretation of the $X(2300)$ resonance. Additional exotic states with dominant hidden-color and K-type components are predicted in the mass ranges $1.6-3.1$ GeV for tetraquarks and $2.6-3.2$ GeV for pentaquarks. The internal structure of these states is analyzed through their sizes, magnetic moments, and wave-function compositions, highlighting the essential role of channel coupling and exotic color configurations. Finally, promising two-body strong decay channels are proposed to facilitate future experimental searches.

hep-ph↗

arXiv2026

Gross-Pitaevskii-Poisson equations with a $\xi R \phi^4$ non-minimal coupling term

In scenarios where the Peccei-Quinn symmetry breaks after inflation, small-scale axion inhomogeneities may gravitationally collapse into bound structures. The evolution of these systems is typically modeled through cosmological perturbation theory applied to the Einstein-Klein-Gordon equations. In the non-relativistic regime, this framework reduces to the Gross-Pitaevskii-Poisson or Schr\"odinger-Poisson equations, depending on whether axion self-interactions are taken into account. In this work, a non-minimal gravitational coupling term $\xi R \phi^4$ is included into the axion's relativistic action as a way to introduce a gravitationally mediated pairwise interaction. By performing a perturbative expansion and subsequently taking the non-relativistic limit, an alternative set of equations that govern the early stages of structure formation is obtained.

hep-ph↗

arXiv2025

Triply heavy tetraquarks $\bar{b}c\bar{q}c$ and $\bar{c}b\bar{q}b$ in a constituent quark model

A systematic investigation of $S$-wave triply heavy tetraquark systems with quark content $\bar{b}c\bar{q}c$ and $\bar{c}b\bar{q}b$ $(q = u,\,d,\,s)$, spin-parity quantum numbers $J^P=0^+$, $1^+$, $2^+$ and isospin $I=0,\,\frac{1}{2}$, is carried out within the constituent quark model framework. The four-body bound and resonance states are determined by solving the Schr\"odinger equation employing the high-precision and efficient Gaussian Expansion Method (GEM) in conjunction with the powerful Complex Scaling Method (CSM). Besides, a comprehensive coupled-channel analysis of the $S$-wave tetraquark systems is performed, taking into account meson-meson, diquark-antidiquark and K-type configurations, as well as all allowed color structures. Several narrow resonant states are identified in each $I(J^P)$ channel. In particular, resonances for the $\bar{b}c\bar{q}c$ system are found in the mass range of $8.87-9.36$ GeV, while those for the $\bar{c}b\bar{q}b$ system lie between $12.13-12.45$ GeV. Most of the predicted resonances are compact tetraquark states with sizes smaller than $1.0$ fm, although four states exhibit more extended structures with sizes around $1.3$ fm, suggesting a more loosely bound nature. Magnetic moments and dominant wave function components of these exotic states are also analyzed. The results indicate that K-type configurations play a major role in the structure of the observed resonances. Finally, possible strong decay channels (golden modes) for these states are theoretically proposed.

hep-ph↗

arXiv2025

Imaging the charge distributions of flavor-symmetric and -asymmetric mesons

We investigate the internal structure of a comprehensive set of pseudoscalar and vector mesons, including both flavor-symmetric and flavor-asymmetric systems, by reconstructing their charge distributions from electromagnetic form factors. To achieve this, we employ a Maximum Entropy Method optimized for charge distributions, utilizing previously published form factor data obtained within the Dyson-Schwingers and Bethe-Salpeter equations framework. Furthermore, we calculate the average distance between the valence quark and antiquark that constitute the meson, interpreting it as an estimate for both the meson's spatial size and the typical range of quark motion. Our results reveal that this distance for the lightest quarkonia is approximately five times larger than that for the heaviest. Moreover, due to spin effects, vector mesons exhibit sizes that are 5-15\% larger than their pseudoscalar counterparts.

hep-ph↗

arXiv2025

Constituent-quark-model based coupled-channels calculation of the $\mathbf{bb\bar c\bar c}$ and $\mathbf{bc\bar b\bar c}$ tetraquark systems

We perform a coupled-channels study of the $bb\bar c\bar c$ and $bc\bar b\bar c$ tetraquark systems in a molecular approach using a constituent quark model which has been widely used to satisfactorily describe a broad range of properties of heavy quark hadron systems, either conventional or exotic. Within a molecular framework, the interaction in the heavy quark sector is governed by gluon exchange or confinement forces that are inherently color-dependent. While the $B_c B_c$ system contains two identical quarks, enabling stronger interactions via exchange diagrams, the forces in the $B_c \bar{B}_c$ and $(c\bar{c})-(b\bar{b})$ systems are expected to be significantly weaker. Consequently, the theoretical and experimental analysis of $B_c^{(*)} B_c^{(*)}$, $B_c^{(*)} \bar{B}_c^{(*)}$, and charmonium-bottomonium bound structures could play a crucial role in clarifying the dominant mechanisms responsible for the formation of fully-heavy tetraquarks. For the $bb\bar c\bar c$ tetraquark sector, we find several resonance states with different spin-parity quantum numbers. These resonances are characterized by their proximity, but not too close, to the $B_c^{(\ast)}B_c^{(\ast)}$ thresholds and their large total decay widths, indicating strong decay channels. In contrast, our analysis of the $bc\bar b\bar c$ tetraquark sector reveals no bound states, virtual states, or resonances; suggesting that tetraquark states of the $(c\bar c)-(b\bar b)$ or $B_c^{(\ast)}\bar B_c^{(\ast)}$ molecular type are unlikely to be formed, within our model assumptions.

hep-ph↗

arXiv2025

Parton distribution functions of ground state mesons composed of $c$ or $b$ quarks

The valence quark parton distribution functions (PDFs) of all ground state heavy mesons that composed of $b$ or $c$ quarks, are discussed; namely, the pseudoscalar $\eta_c(1S)$, $\eta_b(1S)$ and $B_c$, together with the corresponding vector ones, $J/\psi$, $\Upsilon(1S)$ and $B_c^\ast$. We use a QCD-inspired constituent quark model, which has been applied with success to conventional heavy mesons, so that one advantage here is that all parameters have already been fixed by previous studies. The wave functions of the heavy mesons in the rest frame are obtained by solving the Schr\"odinger equation, then boosted to its light-front based on Susskind's Lorentz transformation. The PDFs at the hadron scale, are then obtained by integrating out the transverse momenta of the modulus square of the light-front wave function. Our study shows how the valence quark distributions differ between pseudoscalar and vector mesons, as well as among charmonia, bottomonia and bottom-charmed mesons. Comparisons with other theoretical calculations demonstrate that the PDFs obtained herein are in general narrower but align well with the expected patterns. Moreover, each PDF's point-wise behavior is squeezed with respect to the scale-free parton-like PDF.

hep-ph↗

arXiv2024

Origins and impacts of dynamical diquark correlations -- A continuum Schwinger functional approach --

This conference proceedings contribution emphasizes the emergent hadron mass paradigm, which accounts for the majority of the visible mass in the universe, beyond the Higgs boson mechanism. The study delves into the Landau gauge gluon propagator and the dynamical generation of gluon mass, as well as the dressed-quark propagator and dynamical chiral symmetry breaking. It also tackles the baryon bound state problem through the Poincar\'e-covariant Faddeev equation, analyzing the composition and masses of octet and decuplet baryons. The document concludes with a discussion on the electromagnetic form factors of the nucleon and its first radial excitation, providing insights into the quark-diquark structure within baryons.

hep-ph↗

arXiv2024

Triply charm and bottom tetraquarks in a constituent quark model

Singly, doubly and fully charmed tetraquark candidates, \emph{e.g.}, $T_{c\bar{s}}(2900)$, $T^+_{cc}(3875)$ and $X(6900)$ have been recently reported by the LHCb collaboration. Therefore, it is timely to implement a theoretical investigation on triply heavy tetraquark systems; herein, the S-wave triply charm and bottom tetraquarks, $\bar{Q}Q\bar{q}Q$ $(q=u,\,d,\,s;\,Q=c,\,b)$, with spin-parity $J^P=0^+$, $1^+$ and $2^+$, isospin $I=0$ and $\frac{1}{2}$, are systematically studied in a constituent quark model. Besides, all tetraquark configurations, \emph{i.e.} meson-meson, diquark-antidiquark and K-type arrangements, along with any allowed color structure, are comprehensively considered. The Gaussian expansion method (GEM), in combination with the complex-scaling method (CSM), which is quite ingenious in dealing with either bound or resonances, is the approach adopted in solving the complex scaled Schrödinger equation. This theoretical framework has already been applied in various tetra- and penta-quark systems. In a fully coupled-channel calculation within the GEM$+$CSM, narrow resonances are found in each $I(J^P)$ channel of the charm and bottom sector. In particular, triply charm and bottom tetraquark resonances are obtained in $5.6-5.9$ GeV and $15.3-15.7$ GeV, respectively. We provide also some insights of the compositeness of these exotic states, such as the inner quark distance, magnetic moment and dominant wave function component. All this may help to distinguish them in future high energy nuclear and particle experiments.

hep-ph↗

arXiv2024

Study of the $Ω_{ccc}Ω_{ccc}$ and $Ω_{bbb}Ω_{bbb}$ dibaryons in constituent quark model

Dibaryons are the simplest system in which the baryon-baryon interaction, and hence the underlying quark-quark interaction, can be studied in a clear way. Although the only dibaryon known today is the deuteron (and possibly the $d^*$), fully heavy dibaryons are good candidates for bound states because in such systems the kinetic energy is small and the high symmetry of the wave function favours binding. In this study, the possible existence of $Ω_{ccc}Ω_{ccc}$ and $Ω_{bbb}Ω_{bbb}$ dibaryons is investigated in the framework of a constituent quark model that satisfactorily describes the deuteron, the $d^*(2380)$ and the $NN$ interaction. $J^P=0^+$ candidates are found in both systems with binding energies of the order of MeV.

hep-ph↗

arXiv2023

The $\mathbf{\bar{q}q\bar{s}Q}$ $\mathbf{(q=u,\,d;\,Q=c,\,b)}$ tetraquark system in a chiral quark model

Inspired by the experimentally reported $T_{c\bar{s}}(2900)$ exotic states, the $S$-wave $\bar{q}q\bar{s}Q$ $(q=u,\,d;\,Q=c,\,b)$ tetraquarks, with spin-parity $J^P=0^+$, $1^+$ and $2^+$, in both isoscalar and isovector sectors are systematically studied in a chiral quark model. The meson-meson, diquark-antidiquark and K-type arrangements of quarks, along with all possible color wave functions, are comprehensively considered. The four-body system is solved by means of a highly efficient computational approach, the Gaussian expansion method, along with a complex-scaling formulation of the problem to disentangle bound, resonance and scattering states. This theoretical framework has already been successfully applied in various tetra- and penta-quark systems. In the complete coupled-channel case, and within the complex-range formulation, several narrow resonances of $\bar{q}q\bar{s}c$ and $\bar{q}q\bar{s}b$ systems are obtained in each allowed $I(J^P)$-channels. Particularly, the $T_{c\bar{s}}(2900)$ is well identified as a $I(J^P)=1(0^+)$ $\bar{q}q\bar{s}c$ tetraquark state with a dominant molecular structure. Meanwhile, more resonances in $\bar{q}q\bar{s}c$ and $\bar{q}q\bar{s}b$ systems are also obtained within the energy regions $2.4-3.4$ GeV and $5.7-6.7$ GeV, respectively. The predicted exotic states, which are an indication of a richer color structure when going towards multiquark systems beyond mesons and baryons, are expected to be confirmed in future high-energy particle and nuclear experiments.

hep-ph↗

arXiv2023

Hidden-charm pentaquarks with strangeness in a chiral quark model

The LHCb collaboration has recently announced the discovery of two hidden-charm pentaquark states with also strange quark content, $P_{cs}(4338)$ and $P_{cs}(4459)$; its analysis points towards having both hadrons isospin equal to zero and spin-parity quantum numbers $\frac12^-$ and $\frac32^-$, respectively. We perform herein a systematical investigation of the $qqsc\bar{c}$ $(q=u,\,d)$ system by means of a chiral quark model, along with a highly accurate computational method, the Gaussian expansion approach combined with the complex-scaling technique. Baryon-meson configurations in both singlet- and hidden-color channels are considered. The $P_{cs}(4338)$ and $P_{cs}(4459)$ signals can be well identified as molecular bound states with dominant components $ΛJ/ψ$ $(60\%)$ and $Ξ_c D$ $(23\%)$ for the lowest-energy case and $Ξ_c D^*$ $(72\%)$ for the highest-energy one. Besides, it seems that some narrow resonances can be also found in each allowed $I(J^P)$-channel in the energy region of $4.6-5.5$ GeV, except for the $1(\frac12^-)$ where a shallow bound state with dominant $Ξ^*_c D^*$ structure is obtained at $4673$ MeV with binding energy $E_B=-3$ MeV. These exotic states are expected to be confirmed in future high energy experiments.

hep-ph↗

arXiv2023

Quantum dynamics for massless particles in Brinkmann spacetimes

In Classical Dynamics, Eisenhart lift connects the dynamics of null geodesics in a Brinkmann spacetime with a continuous family of Hamiltonian systems by means of a suitable projection. In this work we explore the possibility of building a model for quantum dynamics of massless particles propagating inside a Brinkmann spacetime from the Einsenhart lift. As a result, we describe spatial tunneling between regions classically disconnected for certain class of null geodesics because of curvature. Also we describe entangled states arising from observers who have a limited access to the whole Brinkmann space. Finally we explore the possibility to find a quantum field theory behind these quantum phenomena.

gr-qc↗

arXiv2023

Higher Order Corrections to the Effective Field Theory of Low-energy Axions

Dark matter (DM) can be composed of a collection of axions, or axion-like particles (ALPs), whose existence is due to the spontaneous breaking of the Peccei-Quinn $U(1)$ symmetry which is the most compelling solution of the strong $CP$-problem of Quantum Chromodynamics (QCD). Axions must be spin-$0$ particles with very small masses and extremely weak interactions with themselves as well as with the particles that constitute the Standard Model. In general, the physics of axions is detailed by a quantum field theory of a real scalar field, $ϕ$. Nevertheless, it is more convenient to implement a non-relativistic effective field theory with a complex scalar field, $ψ$, to characterize the mentioned axions in the low-energy regime. A possible application of this equivalent description is to study the collapse of cold dark matter into more complex structures. There have been a few derivations of effective Lagrangians for the complex field $ψ$; resulting to be all equivalent after a nonlocal-space transformation between $ϕ$ and $ψ$ was found, and some other corrections were introduced. Our contribution herein is to further provide higher order corrections, in particular, we compute the effective field theory Lagrangian up to order $(ψ^\astψ)^5$, incorporating also the fast-oscillating field fluctuations into the dominant slowly-varying non-relativistic field.

hep-ph↗

arXiv2023

A contact interaction model for the $η$ and $η'$ mesons in a SDE-BSE approach to QCD: masses, decay widths and transition form factors

We construct a contact interaction model for the $η$ and $η'$ mesons in the SDE-BSE approach to QCD and compute several static properties of these mesons and their transition form factors. We find that this model gives an excellent description of the $η$ and $η'$ static properties, namely their masses, decay width and decay constants. However, a contact interaction disagrees with experimental data for $Q^2$ greater than 2 GeV$^2$, and produces transition form factors in conflict with perturbative QCD prediction. This is not surpring and the reasons for this are explained

hep-ph↗

arXiv2023

Nature of the doubly-charmed tetraquark $T_{cc}^+$ in a constituent quark model

The recently discovered $T_{cc}^+$ is evaluated as a $DD^*$ molecular structure in the $J^P=1^+$ sector. A coupled-channels calculation in charged basis, considering the $D^0D^{*\,+}$, $D^+D^{*\,0}$ and $D^{*\,0}D^{*\,+}$ channels, is done in the framework of a constituent quark model that successfully described other molecular candidates in the charmonium spectrum such as the $X(3872)$. The $T_{cc}^+$ is found as a $D^0D^{*\,+}$ molecule ($87\%$) with a binding energy of $387$ keV/c$^2$ and a width of $81$ keV, in agreement with the experimental measurements. The quark content of the state forces the inclusion of exchange diagrams to treat indistinguishable quarks between the $D$ mesons, which are found to be essential to bind the molecule. The $D^0D^0π^+$ line shape, scattering lengths and effective ranges of the molecule are also analyzed, which are found to be in agreement with the LHCb analysis. We search for further partners of the $T_{cc}^+$ in other charm and bottom sectors, finding different candidates. In particular, in the charm sector we find a shallow $J^P=1^+$ $D^+D^{*\,0}$ molecule ($83\%$), dubbed $T_{cc}^\prime$, just $1.8$ MeV above the $T_{cc}^+$ state. In the bottom sector, we find an isoscalar and an isovector $J^P=1^+$ bottom partners, as $BB^*$ molecules lying $21.9$ MeV/c$^2$ ($I=0$) and $10.5$ MeV/c$^2$ ($I=1$), respectively, below the $B^0B^{*\,+}$ threshold.

hep-ph↗

arXiv2023

Rotation and vibration in tetraquarks

A novel approach is introduced for obtaining precise solutions of the pairing Hamiltonian for tetraquarks, which utilizes an algebraic technique in infinite dimensions. The parameters involved in the transition phase are calibrated based on potential tetraquark candidates derived from phenomenology. Our investigation shows that the rotation and vibration transitional theory delivers a more accurate explanation for heavy tetraquarks compared to other methods utilizing the same formalism. To illustrate the concept, we compute the spectra of several tetraquarks, namely charm, bottom, bottom-charm and open charm and bottom systems, and contrast them with those of other particles.

hep-ph↗

arXiv2023

Charmoniumlike tetraquarks in a chiral quark model

The lowest-lying charmonium-like tetraquarks $c\bar{c}q\bar{q}$ $(q=u,\,d)$ and $c\bar{c}s\bar{s}$, with spin-parity $J^P=0^+$, $1^+$ and $2^+$, and isospin $I=0$ and $1$, are systematically investigated within the theoretical framework of complex-scaling range for a chiral quark model that has already been successfully applied in former studies of various tetra- and penta-quark systems. A four-body $S$-wave configuration which includes meson-meson, diquark-antidiquark and K-type arrangements of quarks, along with all possible color wave functions, is comprehensively considered. Several narrow resonances are obtained in each tetraquark channel when a fully coupled-channel computation is performed. We tentatively assign theoretical states to experimentally reported charmonium-like signals such as $X(3872)$, $Z_c(3900)$, $X(3960)$, $X(4350)$, $X(4685)$ and $X(4700)$. They can be well identified as hadronic molecules; however, other exotic components which involve, for instance, hidden-color channels or diquark-antidiquark structures play a considerable role. Meanwhile, two resonances are obtained at $4.04$ GeV and $4.14$ GeV which may be compatible with experimental data in the energy interval $4.0-4.2$ GeV. Furthermore, the $X(3940)$ and $X(4630)$ may be identified as color compact tetraquark resonances. Finally, we also find few resonance states in the energy interval from $4.5$ GeV to $5.0$ GeV, which would be awaiting for discovery in future experiments.

hep-ph↗

arXiv2022

Arising of trapped surfaces with non-trivial topology from colliding shock waves

The lightlike limit of boosted black hole solutions with one angular momentum is considered for $D \geq4$ dimensions. The boost is performed parallel to the angular momentum and the lightlike limit is done by means of perturbative expansions. We shown that for $D=4$ and $D> 5$ the lightlike limit cannot be extended inside the ring singularity. Then, for $D = 5$ we discuss the arising of trapped surfaces in the head-on collision. We find that, inside the validity of the perturbative analysis we do, a trapped surface with topology $\mathbb R \times \mathbb S_1 \times\mathbb S_1$ seems to appear over the past light cone of the collision below a critical value $a_c$ of the Kerr parameter $a$.

gr-qc↗