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We simulate proton–proton interactions to study densities and multiplicities of charged particles at center-of-mass energy, $\sqrt{s}=7$ TeV in the forward region and compare predictions with experimental findings of LHCb detector. We use different event generators: Sibyll2.3c, EPOS (1.99 and LHC tunes), and DPMJETIII for the simulations. The kinematic region for momentum $p>2\mathrm{\text{GeV}}/c$, transverse momentum $p_T>0.2\mathrm{\text{GeV}}/c$ and $2.0<\eta <4.8$ in pseudorapidity is kept same as in the LHCb experiment for forward region. Predictions of different models and experimental data are presented and compared as a function of transverse momentum and pseudorapidity.

The inclusive spectrum of the charged particles, $\pi$⁰- and $\eta$-mesons produced in the pp collisions at LHC energies were analyzed by fitting them with exponential functions. It was found the spectra were composed of several p${}_T$ regions, which could be characterized by the length of the regions $L_K^c$ and two free fitting parameters $a_K^c$ and $b_K^c$. The study of the $L_K^c$ dependences of the parameters $a_K^c$ and $b_K^c$ and of the energy dependencies of the $L_K^c$, $a_K^c$ and $b_K^c$ showed that the regions can be classified into two groups depending on the values of the $L_K^c$, $a_K^c$ and $b_K^c$. The values of the $L_K^c$ and $b_K^c$ for the first group don’t depend on colliding energy and the type of the particles (though the values of $a_K^c$ increase linearly with energy) whereas the characteristics in the second group of regions show strong dependencies. It was found that the ratio of the length for the $\eta$-mesons to one for the $\pi$⁰-mesons is approximately equal to the ratio of their mass: $〈L_{\eta }〉:〈L_{{\pi }^0}〉\cong m_{\eta }:m_{{\pi }^0}$. Assuming that the values of the $L_K^c$ are directly proportional to the string tension the result could be considered as evidence in favor of parton string fragmentation dynamics. The increase in the lengths for the $\eta$-mesons’ regions is accompanied by an increase of the values for the parameter $b_k^c$. It can mean that the $\eta$-mesons were produced at smaller values of ${\alpha }_S$ compared with that for $\pi$⁰-mesons. The results show that for the first group of regions the lengths of the regions are $\sim$3–5 times greater than the lengths of neighboring, lower p${}_T$ regions. For the second group of regions the lengths of the regions are $\sim$1–2 times greater than the lengths of neighboring lower p${}_T$ region. In the framework of the string fragmentation and hadronization dynamics, this could mean that the particles in the group $I$ of regions are produced through previous-generation strings decays into $\sim$3–5 strings while those in group $II$ originate from previous-generation strings decays into $\sim$2 strings.

We study properties of the off-equatorial motion of charged particles near compact objects endowed with magnetic fields. We pay attention to the circular orbits as well as to the general motion in the related off-equatorial potential ‘halo lobes’.