Chiral condensates in a magnetic field: Accepted!

20/04/2011

ResearchBlogging.org

As my readers could know, I have had a paper written in collaboration with Marco Ruggieri (see here). Marco is currently working at Yukawa Institute in Kyoto (Japan). The great news is that our paper has been accepted for publication on Physical Review D. I am really happy for this very good result of a collaboration that I hope will endure. Currently, we are working on a proof of existence of the critical endpoint for QCD using the Nambu-Jona-Lasinio model. This is an open question that has serious difficulties to get an answer also for a fundamental problem encountered on the lattice: The so-called sign problem. So, a mathematical proof will make a breakthrough in the field with the possibility to be experimentally confirmed at laboratory facilities.

Marco himself proposed a novel approach to get a proof of the critical endpoint to bypass the sign problem (see here).

So, I hope to have had the chance to transmit to my readership the excitement of this line of research and how it is strongly entangled with the understanding of low-energy QCD and the more deep question of the mass gap in the Yang-Mills theory. Surely, I will keep posting on this. Just stay tuned!

Marco Frasca, & Marco Ruggieri (2011). Magnetic Susceptibility of the Quark Condensate and Polarization from
Chiral Models arXiv arXiv: 1103.1194v1

Philippe de Forcrand (2010). Simulating QCD at finite density PoS (LAT2009)010, 2009 arXiv: 1005.0539v2


A simpler explanation for the CDF bump

20/04/2011

ResearchBlogging.org

A lot of fuss arose about the recent almost finding of a new particle at Tevatron (see here). Several exotic hypotheses were put forward mostly looking for physics beyond Standard Model. Of course, being there such a bump at about 3\sigma, we cannot yet cry out for a discovery and more mundane explanations could exist.

Indeed, this is the content of this paper appeared on arXiv. These authors point out some weak points in the analysis done by CDF that amount in the end at an imperfect estimation of the background. This is also my claim as strong interactions are not completely under control. I give here authors’ conclusions for your considerations:

In conclusion, we observe that the dijet invariant mass peak seen in the recent CDF Wjj cross section is completely consistent with the excess observed in the CDF single-top-quark analysis. Both may be explained by an upward fluctuation in the CDF data set of s-channel single-top-quark production, and t-channel production accompanied by an additional low-energy jet. The latter process is poorly modeled by Monte Carlo, and the apparent t-channel excess could simply be an artifact of theoretical uncertainty. Given the modest excess observed by the D0 Collaboration in their single-top-quark data set , we predict the D0 Collaboration would not see a significant dijet invariant mass peak if they follow the CDF procedure.

So, Standard Model strikes back again.

CDF Collaboration, & T. Aaltonen (2011). Invariant Mass Distribution of Jet Pairs Produced in Association with a
W boson in ppbar Collisions at sqrt(s) = 1.96 TeV arXiv arXiv: 1104.0699v1

Zack Sullivan, & Arjun Menon (2011). A standard model explanation of a CDF dijet excess in Wjj arXiv arXiv: 1104.3790v1


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