Abstract:
We review a few topics in Planck-scale physics, with emphasis on possible manifestations in relatively low energy. The selected topics include quantum fluctuations of spacetime, their cumulative effects, uncertainties in energy-momentum measurements, and low energy quantum-gravity phenomenology. The focus is on quantum-gravity-induced uncertainties in some observable quantities. We consider four possible ways to probe Planck-scale physics experimentally: 1. looking for energy-dependent spreads in the arrival time of photons of the same energy from GRBs; 2. examining spacetime fluctuation-induced phase incoherence of light from extragalactic sources; 3. detecting spacetime foam with laser-based interferometry techniques; 4. understanding the threshold anomalies in high energy cosmic ray and gamma ray events. Some other experiments are briefly discussed. We show how some physics behind black holes, simple clocks, simple computers, and the holographic principle is related to Planck-scale physics. We also discuss a formulation of the Dirac equation as a difference equation on a discrete Planck-scale spacetime lattice, and a possible interplay between Planck-scale and Hubble-scale physics encoded in the cosmological constant (dark energy).

Abstract:
The formulae for Planck length, Hawking temperature and Unruh-Davies temperature are derived by using only laws of classical physics together with the Heisenberg principle. Besides, it is shown how the Hawking relation can be deduced from the Unruh relation by means of the principle of equivalence; the deep link between Hawking effect and Unruh effect is in this way clarified.

Abstract:
The Bohr orbits of the hydrogen atom and the Planck constant can be derived classically from the Maxwell equations and the assumption that there is a variation in the electron's velocity about its average value. The resonant nature of the circulating electron and its induced magnetic and Faraday fields prevents a radiative collapse of the electron into the nuclear proton. The derived Planck constant is $h=2pi e^2/alpha c$, where $e$, $alpha$, and $c$ are the electronic charge, the fine structure constant, and the speed of light. The fact that the Planck vacuum (PV) theory derives the same Planck constant independently of the above implies that the two derivations are related. The following highlights that connection.

Special Relativity sets tight constraints on the form of the possible relations between the four-momentum of a particle and the wave four-vector. In fact, we demonstrate that there is just one way, according to Special Relativity, to relate the energy and the momentum of a corpuscle with the characteristics of a plane wave, frequency and wave vector, if the momentum has to flow in the same direction of the wave propagation: the laws must be of direct proportionality like de Broglie and Planck-Einstein equations.

Abstract:
A possible ground state of Quantum Gravity is Wheeler's ``space-time foam'', which can be modeled as a ``Planck-lattice'', a space-time cubic lattice of lattice constant $a_P\simeq 10^{33}$cm, the Planck length. I analyse the structure of the Standard Model defined on the Planck Lattice, in the light of the ``no-go'' theorem of Nielsen and Ninomiya, which requires an extension of the continuum model through Nambu-Jona Lasinio terms, quadrilinear in the Fermi-fields. As a result, a theory of masses (of both fermions and gauge bosons) is seen to emerge that, without Higgs excitations, agrees well with observations.

Abstract:
We show how gauge coupling unification near the Planck scale $M_P\sim 10^{19}$ GeV can be achieved in the framework of supersymmetry, facilitating a full unification of all forces with gravity. Below the conventional GUT scale $M_{GUT}\sim 10^{16}$ GeV physics is described by a Supersymmetric Standard Model whose particle content is that of three complete $\mathbf{27}$ representations of the gauge group $E_6$. Above the conventional GUT scale the gauge group corresponds to a left-right symmetric Supersymmetric Pati-Salam model, which may be regarded as a ``surrogate SUSY GUT'' with all the nice features of SO(10) but without proton decay or doublet-triplet splitting problems. At the TeV scale the extra exotic states may be discovered at the LHC, providing an observable footprint of an underlying $E_6$ gauge group broken at the Planck scale. Assuming an additional low energy $U(1)_X$ gauge group, identified as a non-trivial combination of diagonal $E_6$ generators, the $\mu$ problem of the MSSM can be resolved.

Abstract:
Primordial or Big Bang nucleosynthesis (BBN) is one of the three historical strong evidences for the Big-Bang model together with the expansion of the Universe and the Cosmic Microwave Background radiation (CMB). The recent results by the Planck mission have slightly changed the estimate of the baryonic density Omega_b, compared to the previous WMAP value. This article updates the BBN predictions for the light elements using the new value of Omega_b determined by Planck, as well as an improvement of the nuclear network and new spectroscopic observations. While there is no major modification, the error bars of the primordial D/H abundance (2.67+/-0.09) x 10^{-5} are narrower and there is a slight lowering of the primordial Li/H abundance (4.89^+0.41_-0.39) x 10^{-10}. However, this last value is still ~3 times larger than its observed spectroscopic abundance in halo stars of the Galaxy. Primordial Helium abundance is now determined to be Y_p = 0.2463+/-0.0003.

Abstract:
We propose a cosmological inflationary scenario based on the supergravity-embedded Standard Model supplemented by the right-handed neutrinos. We show that with an appropriate Kahler potential the L-H_u direction gives rise to successful inflation that is similar to the recently proposed gravitationally coupled Higgs inflation model but is free from the unitarity problem. The mass scale $M_R$ of the right-handed neutrinos is subject to the seesaw relation and the present 2-$\sigma$ constraint from the WMAP7-BAO-H_0 data sets its lower bound $M_R\gtrsim$ 1 TeV. Generation of the baryon asymmetry is naturally implemented in this model. We expect within a few years new observational data from the Planck satellite clearly discriminates this model from other existing inflationary models arising from the same Lagrangian, and possibly yields stringent constraints on $M_R$.

Abstract:
This paper considers the Fokker-Planck equation and path integral formulation of the fractional Ornstein-Uhlenbeck process parametrized by two indices. The effective Fokker-Planck equation of this process is derived from the associated fractional Langevin equation. Path integral representation of the process is constructed and the basic quantities are evaluated.

Abstract:
This library (collection of subroutines) is presented for calculating standard quantities in the decomposition of many-electron matrix elements in atomic structure theory. These quantities include the coefficients of fractional parentage, the reduced coefficients of fractional parentage as well as reduced and completely reduced matrix elements for several operators. So the library is assigned for any computational scheme. The software is an implementation of a methodology based on the second quantization in coupled tensorial form, the angular momentum theory in 3 spaces (orbital, spin and quasispin), and the graphical technique of angular momentum. This implementation extends applications in atomic theory capabilities to partially filled f-- shells and has lead to faster execution of angular integration codes.