Propagation of Light in a Hot and Dense Medium

Photons, as quanta of electromagnetic fields, determine the electromagnetic properties of an extremely hot and dense medium. Considering the properties of photons in the interacting medium of charged particles, we explicitly calculate the electromagnetic properties such as the electric permittivity, magnetic permeability, refractive index and the propagation speed of electromagnetic signals in extremely hot and dense background in cosmos. Photons acquire dynamically generated mass in a medium. The screening mass of photon, Debye shielding length and the plasma frequency are calculated as functions of statistical parameters of the medium. We study the properties of the propagating particles in astrophysical systems of distinct statistical conditions. The modifications in the medium properties lead to the equation of state of the system. We mainly calculate all these parameters for extremely high temperatures of the early universe.Comment: 18 page

Scattering of Leptons in Hot and Dense Media

We study the propagation of leptons in hot and dense media and estimate the background corrections to the purely leptonic processes in the early universe and in the stellar cores.Comment: This paper has been withdrawn to include some missing diagrams and give more calculational detail

Nucleosynthesis at Finite Temperature and Density

We study the finite temperature and density effects on beta decay rates to compute their contributions to nucleosynthesis in the early universe and compact stars. We express nucleosynthesis parameters as a function of temperature and density in different astronomical systems of interest. It is explicitly shown that the chemical potential in the core of supermassive and superdense stars affect beta decay and their helium abundance but the background contributions is still dependent on relative temperature. We calculate this contribution for temperature below the chemical potential. It has been noticed that the acceptable background contribution are obtained for comparatively larger values of T as temperature plays a role of regulating parameter in an extremely dense system.Comment: A talk presented at 27th Texas Symposium on Relativistic Astrophysics Dec. 201

Magnetic Moment of Neutrino in Statistical Background

We calculate the magnetic moment of Dirac type of neutrinos in hot and dense background for different ranges of temperature and chemical potential. The properties of neutrinos are studied in the strong magnetic field where the chemical potential of particles is high enough to have more particles than the antiparticles. We show that in this situation, Weyl neutrino seems to explain the neutrino coupling with the magnetic field due to its effective mass which can couple with the magnetic field directly. We also investigate the electromagnetic properties of Weyl neutrino due to its effective mass developed in the strong magnetic field.Comment: This paper has been withdrawn to change the title and update some of the result

Magnetic Dipole Moment of Neutrino

We recalculate the magnetic moment of neutrinos in a hot and dense medium. The magnetic dipole moment of neutrinos is modified at high temperature and chemical potential. We show that the magnetic dipole moment of electron neutrino does not get a significant contribution from thermal background to meet the cosmological bound. However, chemical potential contribution to the magnetic moment is non-ignorable even when chemical potential is an order of magnitude greater than the electron mass. It is demonstrated that this effect is more significant in the models with an extended Higgs sector through neutrino mixing

QED Plasma at Finite Temperature up to Two Loops

We study the vacuum polarization tensor of QED (quantum electrodynamics) at high temperatures up to the two loop levels and its effect on the electromagnetic properties of a medium. One loop corrections to QED coupling vanish at low temperatures (T$\leq 10^{10}K$), but they play an important role at high temperature ( T$\geq 10^{10}$ K) to study the behavior of QED medium at these temperatures. At low temperatures ( $T \leq m_e$)higher order loops give a tiny correction due to the coupling of radiation with matter and an overlap of hot photon loop with cold fermion loop contributes to this effect. These higher loop contributions does not affect the convergence of perturbative series, and renormalizability of QED is guaranteed at temperatures around neutrino decoupling. We use the renormalization scheme of QED at finite temperature in real-time formalism to study the dynamically generated mass of photon indicating the plasmon production in such a medium. Temperature dependence of this QED plasma parameters is discussed. We explicitly show that this behavior of a thermal medium exists upto temperatures of a few MeV only. We compare the first order and second order effects upto the 4MeV temperature and demonstrate that the higher order contributions are smaller than the lower order contributions proving the renormalizability of the theory. The lowest order contributions are sufficiently smaller than the original value as well.Comment: 10 latex pages with 7 figures: Submitted for publication. arXiv admin note: text overlap with arXiv:hep-ph/061213

How to Control a Decrease in Physics Enrollment?

Physics community is generally concerned about the decrease in Physics enrollment. Due to the deficiency of specially qualified Physics teachers, high school Physics is sometimes taught by general science teachers who may not be trained to motivate students to study Physics. These students will neither be inclined to register into Physics courses nor plan to teach Physics. They will be unable to find out the relevance of Physics with daily life, its application in different disciplines and even the job market. In this situation, we have to carefully make the existing Physics programs more attractive, instead of closing them down. We discuss teaching methodology and course requirements that will help to make Physics programs more attractive and preferable for incoming students. However, we emphasize to set our goals and plan to increase enrollment in parallel steps such as proper information about the program, help in developing a required mathematics background, offering scholarships, teaching assistantship or internships and involving them in research. Also we need to make Physics programs more interesting with the interdisciplinary courses and other electives which students may like. We will have to work on the retention rate to maintain enrollment without compromising on standards. However, we still have to develop a complete understanding of the problem and keep looking for a better solution.Comment: 14 Pages. Same material was presented as a poster in PhysTEC Meeting (19-20 May)2014 in Austin, T

The Decrease in Physics Enrollment

We discuss and analyze the fact that physics is generally losing its ability to captivate students who may possess the potential to enhance the quality of our future in this age of technology. We have tried to investigate the reasons behind this low enrollment in the light of the results of a few surveys with the undergraduate students in different physics courses and in current relevant college programs. It is not an exclusively descriptive issue, so our analysis is a way to delineate the details of the matter leading to the suggestions for future improvements.Comment: 22 page

Renormalization of QED near Decoupling Temperature

We study the effective parameters of QED near decoupling temperatures and show that the QED perturbative series is convergent, at temperatures below the decoupling temperature. The renormalization constant of QED acquires different values if a system cools down from a hotter system to the electron mass temperature or heats up from a cooler system to the same temperature. At T = m, the first order contribution to the electron selfmass, {\delta}m/m is 0.0076 for a heating system and 0.0115 for a cooling system and the difference between two values is equal to 1/3 of the low temperature value and 1/2 of the high temperature value around T~m. This difference is a measure of hot fermion background at high temperatures. With the increase in release of more fermions at hotter temperatures, the fermion background contribution dominates and weak interactions have to be incorporated to understand the background effects.Comment: 3 Figures and 1 Table, Physics Research International, Volume 2014, ID 489163. arXiv admin note: substantial text overlap with arXiv:1205.293

Better Physics Teaching Can Increase Physics Enrollment

Our main goal is to develop plans to increase physics enrollment. Once again we thoroughly analyze the problem from the beginning and reach the conclusion that the most appropriate starting point in this direction should be to look into K-12 teaching. We give a few recommendations to improve science/physics teaching at K-12 level. It is proposed that the quickest way to make some advancement is to start teacher training or refresher courses for school teachers to fill up their gaps in knowledge. We suggest a comparison of the affectivity of different methods of teaching to decide which one of them works better under what type of circumstances. We also propose a few steps to improve physics teaching standards at the higher levels.Comment: 8 latex page