Regular Series


Vol. 49 (2018), No. 2, pp. 99 – 197


Stopped Nucleons in Configuration Space

abstract

In this note, using the simplified colour string model, we study the configuration space distribution of stopped nucleons in heavy-ion collisions. Given this model, we find that the stopped nucleons from the target and the projectile end up separated from each other by a distance which increases with the collision energy. In consequence, for the center-of-mass energies larger than 6 or 10 GeV (depending on the details of the model), it appears that the stopped nucleons are not necessarily in thermal and chemical equilibrium, and the net-baryon density reached is likely not much higher than that already present in the colliding nuclei.


Conformal Standard Model and Inflation

abstract

This article presents a possible inflation scenario as a consequence of non-minimal gravitational couplings in the Conformal Standard Model. The model consists, in comparison to the SM, of additional right-chiral neutrinos and complex scalars coupled to the right-chiral neutrinos but not to the SM particles. The inflation is driven by two non-minimally coupled fields, one being the usual Higgs and the other one of the sterile scalars. It turns out that in this model, the tensor-to-scalar ratio and spectral index can match the current data for a wide range of parameters.


Fermion Localization on the Deformed Brane with the Derivative Coupling Mechanism

abstract

In this paper, by using two localization mechanisms which one is the well-known Yukawa coupling and the other is the new derivative fermion–scalar coupling, we reinvestigate the fermion field localization on deformed branes. These branes are generated by the so-called two-kink solutions, obtained after a deformation of a \(\phi ^{4}\) potential. The study of deformed defects is important because it contains internal structures which may have implications in braneworld scenarios. Because of existing freedom in the form of the Yukawa coupling, we consider a function of the warp factor for both coupling mechanisms. With two mechanisms, it is shown that massless zero modes of fermion fields are localized on the deformed brane depending on the value of the coupling constant which is independent of the deformation parameter. Moreover, we find that both mechanisms can result in a volcano-like potential of the fermion massive modes associated to the corresponding Schrödinger-like equation. Furthermore, effects of the internal structure on the zero mode and fermion effective potentials are addressed.


Ultrarelativistic Bound States in the Shallow Spherical Well

abstract

We determine approximate eigenvalues and eigenfunctions shapes for bound states in the 3D shallow spherical ultrarelativistic well. Existence thresholds for the ground state and lowest excited states are identified, both in the purely radial and orbitally nontrivial cases. This contributes to an understanding of how energy may be stored or accumulated in the form of bound states of Schrödinger-type quantum systems that are nearly massless or devoid of any mass.


A New Theorem on the Representation Structure of the SL\((2, \mathbb {C})\) Group Acting in the Hilbert Space of the Quantum Coulomb Field

abstract

Using the results obtained by Staruszkiewicz in Acta Phys. Pol. B 23, 591 (1992) and in Acta Phys. Pol. B 23, 927 (1992), we show that the representations acting in the eigenspaces of the total charge operator corresponding to the eigenvalues \(n_1, n_2\) whose absolute values are less than or equal \(\sqrt {\pi /e^2}\) are inequivalent if \(|n_1| \neq |n_2|\) and contain the supplementary series component acting as a discrete component. On the other hand, the representations acting in the eigenspaces corresponding to eigenvalues whose absolute values are greater than \(\sqrt {\pi /e^2}\) are all unitarily equivalent and do not contain any supplementary series component.


Comment on “Solution of the Specific Model of Five-body Problem to Investigate the Effective Alpha–Nucleon Interaction in a Partial-wave Analysis”

abstract

The authors argue that the five-body binding energies obtained from the solution of the coupled Yakubovsky integral equations by E. Ahmadi Pouya and A.A. Rajabi [Acta Phys. Pol. B, 48, 1279 (2017)] are incorrect and should be discarded. The theory and formalism of the paper have serious mistakes and the numerical results are not trustable and cannot be validated.


ERRATUM for Acta Phys. Pol. B 48, 1061 (2017)

Development of the LHCb VELO Monitoring Software Platform


ERRATUM for Acta Phys. Pol. B 48, 1157 (2017)

Production Measurements at the LHCb


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