arXiv subjects

M. A. Bedolla

Publications and source records attributed to M. A. Bedolla.

9 recordsLinked to original sources

arXiv2026

Elastic Form Factors of Axial-Vector Mesons: A Contact Interaction Exploration

We employ a symmetry-preserving treatment of the contact interaction within the coupled for- malism of Schwinger-Dyson and Bethe-Salpeter equations to calculate the elastic form factors of axial-vector mesons. In this study, we present the computation of the charge radii, magnetic mo- ments, and quadrupole moments of axial-vector mesons, including those composed of light quarks, heavy quarks or a light and a heavy quark. Our findings indicate that the electric form factor for axial-vector mesons, like that of vector mesons, crosses zero. Furthermore, this crossing occurs at a lower value for axial-vector mesons than for vector mesons. The results for vector-axial mesons follow a similar hierarchy in charge radii as observed for S, PS, and V mesons, with radii decreasing as the mass of the dressed quarks increases. We also include a term associated with the anoma- lous magnetic moment in the quark-photon vertex. This term has a noticeable impact on both the axial-vector magnetic moment and quadrupole moment, leading to significant percentage changes in their values. We compare our results with those obtained from other models whenever available.

hep-ph↗

arXiv2024

Electric, Magnetic and Quadrupole Form Factors and Charge Radii of Vector Mesons: From Light to Heavy Sector in a Contact Interaction

We present a detailed survey of electric, magnetic and quadrupole form factors of light and heavy spin-1 vector mesons. It complements our analogous analysis of the electromagnetic form factors of pseudoscalar and scalar mesons reported earlier. Our formalism is based upon the Schwinger-Dyson equations treatment of a vector $\times$ vector contact interaction and the Bethe-Salpeter equation description of relativistic two-body bound states. We compute the form factors, associated moments and charge radii, comparing these quantities to earlier theoretical studies and experimental results if and when possible. We also investigate the quark-mass dependence of the charge radii and find the anticipated hierarchy such that it decreases with increasing dressed quark masses. In addition, our analysis shows that the magnetic moment is independent of the mass of the light and heavy mesons. Our results agree with most measurements reported earlier, finding a negative quadrupole moment, implying the charge distribution is oblate.

hep-ph↗

arXiv2023

Electromagnetic Form Factors and Charge Radii of Pseudoscalar and Scalar Mesons: A Comprehensive Contact Interaction Analysis

We carry out a comprehensive survey of electromagnetic form factors of all light, heavy and heavy-light ground-state pseudoscalar and scalar mesons. Our analysis is based upon a Schwinger-Dyson equations treatment of a vector $\times$ vector contact interaction. It incorporates confinement and ensures axial vector and vector Ward-Takahashi identities are satisfied along with the corresponding corollaries such as the Goldberger-Treiman relations. The algebraic simplicity of the model allows us to compute the form factors at arbitrarily large virtualities of the probing photon momentum squared with relative ease. Wherever possible and insightful, we compare our results for the electromagnetic form factors and the charge radii with those obtained earlier through Schwinger-Dyson equations, lattice and with experimental observations available. We also comment on the scope and shortcomings of the model.

hep-ph↗

arXiv2020

Spectrum of fully-heavy tetraquarks from a diquark+antidiquark perspective

Using a relativized diquark model Hamiltonian, we calculate the masses of $J^{PC}=0^{++}$ ground-state tetraquarks in the following systems: $b s \bar b \bar s$, $bb \bar n \bar n$ ($n=u, d$), $bb \bar s \bar s$, $cc\bar c \bar c$, $b b \bar b \bar b$, $b c\bar b \bar c$ and $b b \bar c \bar c$. We also compute extensive spectra for the fully-heavy quark flavour combinations. Finally, as a test of the diquark model approach, we compute the masses of fully-heavy baryons in the diquark model. Our results may be compared soon to the forthcoming experimental data for fully-heavy three-quark systems.

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arXiv2020

Diquark Correlations in Hadron Physics: Origin, Impact and Evidence

The last decade has seen a marked shift in how the internal structure of hadrons is understood. Modern experimental facilities, new theoretical techniques for the continuum bound-state problem and progress with lattice-regularised QCD have provided strong indications that soft quark+quark (diquark) correlations play a crucial role in hadron physics. For example, theory indicates that the appearance of such correlations is a necessary consequence of dynamical chiral symmetry breaking, viz. a corollary of emergent hadronic mass that is responsible for almost all visible mass in the universe; experiment has uncovered signals for such correlations in the flavour-separation of the proton's electromagnetic form factors; and phenomenology suggests that diquark correlations might be critical to the formation of exotic tetra- and penta-quark hadrons. A broad spectrum of such information is evaluated herein, with a view to consolidating the facts and therefrom moving toward a coherent, unified picture of hadron structure and the role that diquark correlations might play.

hep-ph↗

arXiv2019

The $Ω_{c}$-puzzle solved by means of spectrum and strong decay amplitude predictions

The observation of new $Ω_{c}=ssc$ states by LHCb \cite{Aaij:2017nav} and the confirmation of four of them by Belle \cite{Yelton:2017qxg} may represent an important milestone in our understanding of the quark organization inside hadrons. By providing results for the spectrum of $Ω_{c(b)}$ baryons and predictions for their $Ξ_{c(b)}^{+}K^{-}$ decay channels, we suggest a possible solution to the $Ω_{c}$ quantum number puzzle. We also discuss why the set of $Ω_{c(b)}$ baryons are the most suitable environment to test the validity of three-quark and quark-diquark effective degrees of freedom. Finally, we calculate the masses and the partial decay widths of the $Ξ_b(6227)$ and $Σ_b(6097)$ states, just observed by LHCb \cite{Aaij:2018yqz,Aaij:2018tnn}. Our results are in good agreement with LHCb experimental data.

hep-ph↗

arXiv2019

Heavy-light mesons spectra in a contact interaction

We present the spectrum and decay constants of heavy-light mesons in four different channels: pseudo-scalar, vector, scalar and axial vector. We extend the framework for our previous analysis in a unified symmetry-preserving Schwinger-Dyson equations treatment of a vector$\times$vectord contact interaction. Despite the simplicity of our model, 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

The baryo-quarkonium picture for hidden-charm and bottom pentaquarks and LHCb $P_{\rm c}(4380)$ and $P_{\rm c}(4450)$ states

We study baryo-charmonium [$η_{\rm c}$- and $J/ψ$-$N^*$, $η_{\rm c}(2S)$-, $ψ(2S)$- and $χ_{\rm c}(1P)$-$N$] and baryo-bottomonium [$η_{\rm b}(2S)$-, $Υ(2S)$- and $χ_{\rm b}(1P)$-$N$] bound states, where $N$ is the nucleon and $N^*$ a nucleon resonance. In the baryo-quarkonium model, the five $qqq Q \bar Q$ quarks are arranged in terms of a heavy quarkonium core, $Q \bar Q$, embedded in light baryonic matter, $qqq$, with $q = u$ or $d$. The interaction between the $Q \bar Q$ core and the light baryon can be written in terms of the QCD multipole expansion. The spectrum of baryo-charmonium states is calculated and the results compared with the existing experimental data. In particular, we can interpret the recently discovered $P_{\rm c}(4380)$ and $P_{\rm c}(4450)$ pentaquarks as $ψ(2S)$-$N$ and $χ_{\rm c2}(1P)$-$N$ bound states, respectively. We observe that in the baryo-bottomonium sector the binding energies are, on average, slightly larger than those of baryo-charmonia. Because of this, the hidden-bottom pentaquarks are more likely to form than their hidden-charm counterparts. We thus suggest the experimentalists to look for five-quark states in the hidden-bottom sector in the $10.4-10.9$ GeV energy region.

hep-ph↗

arXiv2017

Heavy quarkonia in a contact interaction and an algebraic model: mass spectrum, decay constants, charge radii and elastic and transition form factors

For the flavor-singlet heavy quark system of bottomonia, we compute the masses of the ground state mesons in four different channels, namely, pseudo-scalar ($η_{b}(1S)$), vector ($Υ(1S)$), scalar ($χ_{b_0}(1P)$) and axial vector ($χ_{b_{1}}(1P)$). We also calculate the weak decay constants of the $η_{b}(1S)$ and $Υ(1S)$ as well as the charge radius of $η_{b}(1S)$. It complements our previous study of the corresponding charmonia systems: $η_c(1S)$, $J/Ψ(1S)$, $χ_{c_0}(1P)$) and ($χ_{c_{1}}(1P)$). The unified formalism for this analysis is provided by a symmetry-preserving Schwinger-Dyson equations treatment of a vector$\times$vector contact interaction. Whenever a comparison is possible, our results are in fairly good agreement with experimental data and model calculations based upon Schwinger-Dyson and Bethe-Salpeter equations involving sophisticated interaction kernels. Within the same framework, we also report the elastic and transition form factors to two photons for the pseudo-scalar channels $η_{c}(1S)$ and $η_{b}(1S)$ in addition to the elastic form factors for the vector mesons $J/Ψ$ and $Υ$ for a wide range of photon momentum transfer squared ($Q^2$). For $η_{c}(1S)$ and $η_{b}(1S)$, we also provide predictions of an algebraic model which correlates remarkably well between the known infrared and ultraviolet limits of these form factors.

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