AGH UST scientists publish in Nature

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We are pleased to inform that one of the most important world scientific journals has published an article whose co-authors are the scientists and researchers of the Faculty of Physics and Applied Computer Science – Leszek Adamczyk, DSc, Łukasz Fulek, MSc, and Rafał Sikora, MSc. 

 

The STAR Experiment (acronym for Solenoidal Tracker at RHIC), the largest experiment on Relativistic Heavy Ion Collider (RHIC) located at the Brookhaven National Laboratory in the USA, published an article (Nature 527, 345-348 [2015]) related to the measurement of (strong) interaction force between antiprotons. The results confirm that, similarly to protons, antiprotons also attract one another. Additionally, the following two key parameters describing interactions have been measured for antiprotons for the first time: diffusion length and effective length of interaction. Within the limits of measurement accuracy, these parameters for antiprotons are consistent with their counterparts for proton interactions.  

 

The analysis was carried out on data coming from the relativistic collisions of gold nuclei, in which large numbers of protons and antiprotons are produced. The range of strong interactions is in the order of femtometres, and it is not possible to measure such lengths in the experiment. However, it is possible to measure quite precisely the momentum of antiprotons, that is why information concerning the dependence of interaction force on distance was obtained through the analysis of correlations between antiprotons in momentum space. For this purpose, transformation (parallel with the Fourier transform) from the domain of momentum to the domain of position was used.  

 

It is the first in the world direct measurement of the range and force of strong interaction between antiprotons, but additionally, it is important in research on the sources of asymmetry between matter and antimatter observed in the universe. The measurement results indicate that strong interaction within the limits of measurement accuracy is the same between protons and antiprotons. The conclusion itself comes as no surprise since the symmetry of strong interaction caused by the transformation of matter into antimatter had already been indicated much more precisely by the results of other experiments. However, the measurement performed by the STAR Experiment differs in quality from the other measurement results, which proves its high importance despite its relatively little accuracy.

 

It is worth mentioning that in 2015 Nature published another article written by the scientists of the faculty. It was an LHCb collaboration work (M. Firlej, T. Fiutowski, M. Idzik, P. Morawski, J. Moroń, A. Obłąkowska-Mucha, K. Świentek, T. Szumlak) entitled “Observation of the rare Bs0→μ+μ– decay from the combined analysis of CMS and LHCb data”, dealing with the subject of the first Bs meson decay into muons, with the non-preservation of strangeness. 

 

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