Hi, there! In this short note I am going to introduce you into a big problem from a simple integral I use to call “the cosmological integral” (it should be the cosmological energy density integral, but it is too long…). … Continue reading

# Category Archives: QFT

Are diamonds and other (crystalline) jewels/gemstones forever? Well, if protons are stable they are. If not, you are lost! We are all lost indeed in such a case…(However, I am sure that Superman would be fine to know the fact … Continue reading

In 2012, July 4th…We had the Higgsdependence day! A SM Higgs-like resonance was discovered at the LHC and was announced to the world. Today, we celebrate this discovery of the Higgs-like thing or particle almost 3 years ago. So let … Continue reading

The question of the origin of mass is one of the more important issues in theoretical physics. The existence (or not) of extra dimensions of space and time will likely affect to the final solution of this unsolved problem. The … Continue reading

An interesting but relatively unknown variation of the Bohr model is to use a logarithmic potential energy. In that case, we have (1) (2) (3) Bohr quantization rules impose and that so (4) and then (5) (6) (7) The momentum … Continue reading

The Bohr model of the hydrogen atom is a cool and nice “toy model”. It serves as a prototype in many applications, even if it is not fully “quantum”. It does provide many applications. In this post, and the followings, … Continue reading

The year 2013 is coming to its end…And I have a final gift for you. An impossible post! This year was the Bohr model 100th anniversary. I have talked about this subject already, here, here and here. The hydrogen spectrum is very important in Astronomy, … Continue reading

Final round of this thread! Approximate methods We will evaluate the path integral (PI) using an approximation known as “saddle point”. It is a semiclassical approximation sometimes referred as the method of steepest descent. Moreover, it is based on the … Continue reading

Round 3! Fight… with path integrals! XD Introduction: generic aspects Consider a particle moving in one dimension (the extension to ND is trivial), the hamiltonian being of the usual form: The fundamental question and problem in the path integral (PI) … Continue reading

Are you gaussian? Are you normal? My second post about the path integral will cover functional calculus, and some basic definitions, properties and formulae. What is a functional? It is a gadget that produces a number! Numbers are cool! Functions … Continue reading