## From arxiv today

25/10/2011

Today the daily from arxiv is particularly rich. A couple of papers are from my friend Marco Ruggieri, one in collaboration with Raul Gatto (see here) and the other is the contribution to Paris Conference proceedings (see here). Marco is currently using a Nambu-Jona-Lasinio model to understand the behavior of hadronic matter at high temperatures and densities. These works imply the use of a chiral chemical potential that has the benefit to permit an identification of the critical end-point on the lattice without the infamous sign problem, as Marco showed quite recently (see here). These works are well founded as the Nambu-Jona-Lasinio model is the right low-energy limit of QCD (see here and here).

Another theoretical confirmation on my result on the beta function for Yang-Mills theory appeared today (see here). This author works out classical solutions to Yang-Mills theory and derives a “beta function” of the form $4\alpha_s$, exactly the one I get (see here). This result marks evidence of an infrared trivial fixed point for this theory and the correctness of the mapping on a scalar field. This paper gives just a clue as the treatment remains at a classical level.

Last but not least, the complete Coleman’s lectures appeared finally on arxiv (see here). We have to give a great thank to Bryan Chen and Yuan-Sen Ting for their excellent work. These lectures are a reference today yet and I hope they will see the light in a book with some addenda from most of Coleman’s famous students.

Raoul Gatto, & Marco Ruggieri (2011). Hot Quark Matter with an Axial Chemical Potential arXiv arXiv: 1110.4904v1

Marco Ruggieri (2011). Quark Matter with a Chiral Chemical Potential arXiv arXiv: 1110.4907v1

Marco Ruggieri (2011). The Critical End Point of Quantum Chromodynamics Detected by Chirally
Imbalanced Quark Matter Phys.Rev.D84:014011,2011 arXiv: 1103.6186v2

Marco Frasca (2008). Infrared QCD Int.J.Mod.Phys.E18:693-703,2009 arXiv: 0803.0319v5

Kei-Ichi Kondo (2010). Toward a first-principle derivation of confinement and chiral-symmetry-breaking crossover transitions in QCD Phys. Rev. D, 82 065024 (2010) arXiv: 1005.0314v2

Ding-fang Zeng (2011). Confinings of QCD at purely classic levels arXiv arXiv: 1110.5054v1

Marco Frasca (2010). Mapping theorem and Green functions in Yang-Mills theory PoS FacesQCD:039,2010 arXiv: 1011.3643v3

Sidney Coleman (2011). Notes from Sidney Coleman’s Physics 253a arXiv arXiv: 1110.5013v1

## Sidney Coleman’s QFT lectures

21/03/2011

This post is just to point out to my readers that the lectures of Sidney Coleman on QFT are now available in TeX and pdf format. I have taken this information from Lubos’ site. The link for the full pdf is this. For this excellent work the person to be grateful is Bryan Chen a former Lubos’ student. These lectures give an idea of the greatness of Coleman also as a teacher.

For the readers of my blog pursuing active research in my same areas a relevant paper by him is there are no classical glueballs. Coleman’s conclusion goes like

…there are no finite-energy non-singular solutions of classical Yang-Mills theory in four-dimensional Minkowski space that do not radiate energy out to spatial infinity…

and this agrees quite well with my exact solutions that do not seem to have finite energy (see here) and so, Coleman’s theorem is evaded. Indeed, if you want to have a field to generate a mass, you will need either a finite volume or a running coupling.

Coleman, S. (1977). There are no classical glueballs Communications in Mathematical Physics, 55 (2), 113-116 DOI: 10.1007/BF01626513

Marco Frasca (2009). Exact solutions of classical scalar field equations arxiv arXiv: 0907.4053v2

## Quote of the day

25/06/2009

“The career of a young theoretical physicist consists of treating the harmonic oscillator in ever-increasing levels of abstraction.”

Sidney Coleman

Taken from David Tong’s page at Cambridge (see here).