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Assuming isospin conservation, the decay of a c c ¯ vector meson into the Λ Σ ¯ 0 + c . c . final state is purely electromagnetic. At the leading order, the c c ¯ vector meson first converts into a virtual photon that, then produces the Λ Σ ¯ 0 + c . c . final state. Moreover, such a mechanism, i.e., the virtual photon coupling to Λ Σ ¯ 0 + c . c . , is the sole intermediate process through which, in Born approximation, the reaction e + e - → Λ Σ ¯ 0 + c . c . does proceed. It follows that any significant difference between the amplitudes of the processes c c ¯ → Λ Σ ¯ 0 + c . c . and e + e - → Λ Σ ¯ 0 + c . c . at the c c ¯ mass must be ascribed to an isospin-violating contribution in the c c ¯ decay. In Ferroli et al. (Eur Phys J C 80: 903, 2020) we studied the decay of the ψ ( 2 S ) vector meson into Λ Σ ¯ 0 + c . c . and, on the light of the large branching fraction BR 18 ( ψ ( 2 S ) → Λ Σ ¯ 0 + c . c . ) = ( 1.23 ± 0.24 ) × 10 - 5 , published in the 2018 edition of the Review of Particle Physics (Tanabashi et al. in Phys Rev D 98: 030001, 2018), we claimed either the presence of a significant isospin-violating contribution or, with a lesser emphasis, a “not complete reliability of the only available datum”. In any case, we propose a new measurement. Apparently, our second and considered less serious hypothesis was the right one, indeed the branching fraction published in the 2024 edition of the Review of Particle Physics (Navas et al. in Phys Rev D 110: 030001, 2024) is BR ( ψ ( 2 S ) → Λ Σ ¯ 0 + c . c . ) = ( 1.6 ± 0.7 ) × 10 - 6 , more than seven times lower with the error that increased from ∼ 20 % to ∼ 45 % .

A very general class of axially symmetric metrics in general relativity (GR) that includes rotations is used to discuss the dynamics of rotationally supported galaxies. The exact vacuum solutions of the Einstein equations for this extended Weyl class of metrics allow us to rigorously deduce the following: (i) GR rotational velocity always exceeds the Newtonian velocity (thanks to Lenz’s law in GR). (ii) A non-vanishing intrinsic angular momentum ( J ) for a galaxy demands the asymptotic constancy of the Weyl (vectorial) length parameter ( a )—a behaviour identical to that found for the Kerr metric. (iii) Asymptotic constancy of the same parameter a also demands a plateau in the rotational velocity. Unlike the Kerr metric, the extended Weyl metric can and has been continued within the galaxy, and it has been shown under what conditions Gauß and Ampére laws emerge along with Ludwig’s extended gravito-electromagnetism (GEM) theory with its attendant non-linear rate equations for the velocity field. Better estimates (than that from the Newtonian theory) for the escape velocity of the Sun have been presented.

Two main findings on electromagnetic hadron form factors focussed a large interest of the hadron physics community in the recent years. One is the decrease of the electric to magnetic form factor ratio when the momentum transfer in electron proton elastic scattering increases. The second is the discovery of regular oscillations of the generalized proton form factors in the annihilation process electron-positron into proton-antiproton. In this talk we propose a coherent interpretation of these findings giving a general, dynamical description of the proton in the space-time frame which is based on the presence of a quantum vacuum at very small distances.

After a just tribute to Guido Barbiellini, we show how the notion of a maximum force (Fmax=c4/4G≃3×1043 Newtons) present on the event horizon of a black hole (BH) can be used in conjunction with the Wilson area rule to obtain the surface confinement of the mass of a BH analogous to the surface confinement of quarks. This is then translated into the central result of the paper that PeV scale protons exist on the surface of the Kerr BH residing at our galactic center, a result in complete agreement with the HAWC Collaboration result of a Pevatron at the galactic center. We conjecture that the supermassive BHs present at the center of most galaxies are not born out of a galactic collapse but that they must have been present since the formation of their hosting galaxy.

Conventional general relativity supplies the notion of a vacuum tension and thus a maximum force Fmax=c4/4G≃3·1043 N that is realized for a black hole. In conjunction with the Wilson area rule, we are thus led to the surface confinement of the mass of a black hole analogous to the surface confinement of quarks. The central result of our paper is that PeV scale protons can be generated on the surface of a Kerr black hole. This result is in concert with the presence at the galactic center of that Pevatron accelerating mechanism first suggested by the H.E.S.S. Collaboration and further confirmed by the HAWC Observatory.

Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay ψ → Λ Σ ¯ 0 + c.c. , where ψ is a vector charmonium, and of the reaction e + e - → Λ Σ ¯ 0 + c.c. at the ψ mass, are parametrized by the same electromagnetic coupling. It follows that, the modulus of such a coupling can be extracted from the data on the two observables: the decay branching fraction and the annihilation cross section. By considering the first two vector charmonia, J / ψ and ψ ( 2 S ) , it is found that, especially in the case of ψ ( 2 S ) , there is a substantial discrepancy between the values of the modulus of the same electromagnetic coupling extracted from the branching ratio and the cross section. We propose, as a possible explanation for such a disagreement, the presence in the decay amplitude of isospin-violating contributions driven by two different mechanisms, that, however, appear to be more favored in the ψ ( 2 S ) than in the J / ψ decays.

We propose a model for the QCD running coupling constant based on the analytical inverse QCD coupling constant concept with an additional regularization in the low momentum region. Analyticity in the q2-complex plane, where q is the four-momentum transfer, is imposed by methods of the Analytic Perturbation Theory. The model incorporates a peculiar low-momentum behavior for αs(q2) as a divergence at q2=0 to retrieve color confinement, without spoiling its correct high-momentum behavior. This was achieved by means of a two-parameter regularization function, for which we considered three possible analytic expressions. In fact, within the framework of the Analytic Perturbation Theory, αs(q2) assumes a finite value for q2=0, at all perturbative orders (infrared stability), hence the infrared divergence cannot be implemented. For this reason, we found it more straightforward to work with its reciprocal, namely, εs(q2)=1/αs(q2), imposing its vanishing at the origin of the q2-complex plane via the multiplication of the aforementioned regularizing functions and the spectral density. Once the two free parameters of the regularization functions were settled by fitting to the experimental values of αs(q2) at the momenta where these data were available and reliable, the model could reproduce the QCD running coupling constant at any other momentum transferred.

The recent measurement of the modulus and phase of the ratio G Λ E / G Λ M , between the electric and the magnetic Λ form factors, performed by the BESIII experiment, offers the unique possibility of exploring for the first time ever the complex structure of this form factor ratio. The investigation is made possible by a dispersive procedure based on analyticity and a set of firstprinciple constraints, that is defined ad hoc.

We discuss the differential elastic pp cross-section data measured at 13 TeV, through the Coulomb Nuclear Interference region until past the dip. We show that data are consistent with the asymptotic predictions from an empirical model and examine the presence of a zero for the real part of the elastic amplitude near the Coulomb region, well before the dip.

In frame of a general view of proton electromagnetic form factors, two recent findings related to reanalyses of data are presented. Recent experiments in the scattering and in the annihilation region provided us with more precise data and/or extending the kinematical region, allowing a deeper analysis and a common view of these fundamental quantities. We will discuss two issues: the discrepancy between the form factors extracted from unpolarized and polarized ep elastic scattering experiments, in connection with the commonly used dipole parametrization; peculiar oscillations in e+e− → p̄p(γ) annihilation cross section, that become periodical when plotted as a function of the 3-momentum of the relative motion of the final proton and antiproton, after subtraction of a smooth function.