Comparison of perturbative and non-perturbative methods in f(R) gravity

In this work, we investigate the structure and properties of neutron stars in $$R^2$$ R 2 gravity using two approaches, viz: the perturbative and non-perturbative methods. For this purpose, we consider NS with several nucleonic, as well as strange EoS generated in the framework of relativistic mean field models. The strange particles in the core of NS are in the form of $$\Lambda $$ Λ hyperons and quarks, in addition to the nucleons and leptons. In both the approaches, we obtain mass–radius relation for a wide range of values of the extra degree of freedom parameter a arising due to modification of gravity at large scales. The mass–radius relation of the chosen equation of states lies well within the observational limit in the case of GR. We identify the changes in the property of neutron star in the background of f(R) gravity, and compare the results in both the methods. We also identify the best suited method to study the modified gravity using the astrophysical observations.

Particle Physics Phenomenology

The most important milestones in particle physics are put in a historical perspective. We follow a century of scattering experiments, from Rutherford to LHC. We introduce successively the concept of the atomic nucleus, the study of β‎-decay and the proposal of the neutrino, the first internal symmetries, the Fermi theory and the Yukawa meson. In parallel we present the technical achievements in accelerator and detector technologies which made these advances possible. We end with the discovery of strange particles, the flavour SU(3) unitary symmetry, and the introduction of the quarks. This chapter follows a descriptive rather than a deductive approach and summa- rises many aspects of particle physics phenomenology which preceded the discovery of the Standard Model.

Study of Strange Particle Production in Central Pb–Pb Collisions at

We study here the transverse momentum spectra of Ks 0 – mesons, A − hyperons and multi–strange (Ξ–, Ω–) particles in the most central Pb–Pb collisions at √SNN = 2.76 TeV for the mid rapidity interval |y| < 0.5 by using two different Monte Carlo simulation models: EPOS–1.99 and EPOS–LHC. The validity of simulation codes of these models is checked for Pb–Pb collisions at √SNN = 2.76 TeV by comparing the simulation data with ALICE experimental data for the same collisions at √SNN = 2.76 TeV. Strange particles ratio i.e. and nuclear modification factors for multi–strange particles have been constructed as function of pT to study these strange particle production and their energy loss mechanism. The simulation models show suppression for the multi–strange particles in the transverse momentum range of 3–7 GeV/c. The outcome agrees with a recent finding by ALICE collaboration where it suggested a possibility that the kinetic freeze–out conditions for strange particles are different from those for non–strange particles