Modern Physics Letters A

Transverse momentum distributions and nuclear modification factor of integrated charged particles yield produced in p+Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV are investigated in mid-rapidity regions of $-0.5<y<0$ at one event multiplicity class 0–5% in the transverse momentum range of $0<p_T<$20 GeV/c. Simulations with EPOS-1.99, EPOS-LHC and QGSJETII-04 are compared with the ALICE data. All three models are in good agreement with each other up to $p_T\sim$3 GeV/c for transverse momentum distributions but after that QGSJETII-04 overpredicts the experimental data. EPOS-LHC seems to describe the experimental data quite well as compared to the other two models. The ratios of the kaons to pions and protons to pions are also presented where again EPOS-LHC provides good agreement with the ALICE data. In case of the nuclear modification factor, for (anti) pions and (anti) kaons, the model distribution is around 1, whereas it is greater than 1 in case of (anti) protons which shows Cronin enhancement.

We construct a static black hole solution of Gauss–Bonnet-massive gravity coupled to nonlinear Maxwell and Yang–Mills fields in higher dimensions. Then we calculate related thermodynamic quantities, check the validity of the first law of black hole thermodynamics and analyze the phase transition behaviors of the black hole in extended phase space.

Causality is one of the most important properties to understand gravity theories. It gives us not only a method to confirm that the gravity theories are really consistent, but also gives implications about the properties which unknown fundamental physics should obey. We investigate the causality of three-dimensional (3D) gravity theories, which are considered to be important, by using the Shapiro time delay effect in the Shock wave geometry. One of such gravity theories is the Zwei-Dreibein Gravity (ZDG) theory, which is a consistent 3D gravity theory. In ZDG theory, the serious problems can be removed that have appeared in another important gravity theory called New Massive Gravity (NMG). We study whether the ZDG theory could preserve the causality without losing the above good properties and how the causality structure is related to the structure of the NMG theory.

Several particles are not observed directly, but only through their decay products. We consider the possibility that they might be fakeons, i.e. fake particles, which mediate interactions but are not asymptotic states. A crucial role to determine the true nature of a particle is played by the imaginary parts of the one-loop radiative corrections, which are affected in nontrivial ways by the presence of fakeons in the loop. The knowledge we have today is sufficient to prove that most non-directly observed particles are true physical particles. However, in the case of the Higgs boson the possibility that it might be a fakeon remains open. The issue can be resolved by means of precision measurements in existing and future accelerators.

We study the merger rate of dark matter PIMBHs (Primordial Intermediate Mass Black Holes). We conclude that the black holes observed by LIGO in GW150914 and later events were probably not dark matter PIMBHs but rather the result of gravitational collapse of very massive stars. To study the PIMBHs by gravitational radiation will require a detector sensitive to frequencies below 10 Hz and otherwise more sensitive than LIGO. The LISA detector, expected to come online in 2034, will be useful at frequencies below 1 Hz but further gravitational wave detectors beyond LISA, sensitive up to 10 Hz, and higher strain sensitivity will be necessary to fully study dark matter.

We calculate thermal corrections to the Casimir energy of a massless scalar field in the Kerr black hole surrounded by quintessence, taking into account the metrics derived by Ghosh [S. G. Ghosh, Eur. Phys. J. C 76, 222 (2016)] and Toshmatov et al. [B. Toshmatov, Z. Stuchlík and B. Ahmedov, Eur. Phys. J. Plus 132, 98 (2017)]. We compare both results and show that they are almost the same, except very close to the horizons. At $𝜃=\pi /2$, equatorial plane, the results are the same, as should be expected, due to the fact that the metrics coincide in this region.

This work studies the finite temperature effects of a mass dimension one fermionic field, sometimes called Elko field. The equilibrium partition function was calculated by means of the imaginary time formalism and the result obtained was the same for a Dirac fermionic field, even though the Elko field does not satisfy a Dirac-like equation. The high and low temperature limits were obtained, and for the last case the degeneracy pressure due to Pauli exclusion principle can be responsible for the dark matter halos around galaxies to be greater than or of the same order of the galaxy radius. Also, for a light particle of about 1.0 eV and a density of just 1 particle per cubic centimeter, the value of the total dark matter mass due to Elko particles is of the same order of a typical galaxy. Such a result satisfactorily explains the dark matter as being formed just by Elko fermionic particles and also the existence of galactic halos that go beyond the observable limit.

Here, we explore the dynamics of particle near the horizon of charged Mandal–Sengupta–Wadia (MSW) black hole in 2 + 1 dimensions. We analyze angular momentum and potential energy for null and time-like geodesics. We also appraise the high center-of-mass energy of coming particles from rest at infinity near the horizon of the charged MSW black hole in 2 + 1 dimension for the extremal case. Finally, we study the ISCO and MBCO radii for this type of black hole.

Isotropic oscillator and Coulomb problems are known to have interesting correspondence. We focus on two-dimensional (2D) quantum problems and present complete treatment on the correspondence including the Schrödinger equation, eigenfunctions and eigenvalues, and the integrals of motion. We find only partial equivalence. The wave function correspondence is examined introducing local gauge transformation and the emergence of half-quantized vortex with the associated spin-half is established. Vortex structure of the electron proposed by us and the origin of charge are discussed in this paper. Outlook on the implications for QCD and hadron spectrum is outlined.