May 13 – 19, 2018
Venice, Italy
Europe/Zurich timezone
The organisers warmly thank all participants for such a lively QM2018! See you in China in 2019!

Intermittency analysis of proton density as a probe for the critical point of strongly interacting matter in NA61/SHINE

May 15, 2018, 5:00 PM
2h 40m
First floor and third floor (Palazzo del Casinò)

First floor and third floor

Palazzo del Casinò

Poster Phase diagram and search for the critical point Poster Session


Ludwik Turko (University of Wroclaw (PL))


The search for experimental signatures of the critical point (CP) of strongly interacting matter is one of the main objectives of the NA61/SHINE experiment at the CERN SPS. In the course of the experiment, an energy (beam momentum 13A – 150/158A GeV/c) and system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La) scan is performed. Proposed observables include non-monotonic fluctuations of integrated quantities, as well as local critical fluctuations connected to the critical behavior of the order parameter in the CP neighborhood, which scale according to universal power-laws.

Proton density fluctuations are investigated as a possible order parameter of the phase transition in the neighborhood of the CP by performing an intermittency analysis of the proton second scaled factorial moments (SSFMs) in transverse momentum space. A previous analysis of this kind [1] revealed significant power-law fluctuations in the NA49 heavy-ion collision experiment for the Si+Si system at 158A GeV/c. The fitted power-law exponent was consistent with the theoretically expected critical value within uncertainties, a result suggesting a baryochemical potential for the critical point in the vicinity of ~250 MeV.

The intermittency analysis is extended to systems of intermediate size as studied by NA61/SHINE, the primary candidates being the Be+Be and Ar+Sc systems at 150A GeV/c. Statistical techniques are developed for the calculation of scaled factorial moments which allow to subtract non-critical background and enhance the signal in case of low statistics. The analysis is supplemented by both critical and non-critical Monte Carlo simulations, by which one can estimate non-critical background effects on the quality and magnitude of uncertainties of the intermittency power-law fit, as well as explore the possibility of non-critical effects producing an intermittency signal.


[1] T. Anticic et al, Eur. Phys. J. C 75: 587 (2015).

Content type Experiment
Centralised submission by Collaboration Presenter name already specified
Collaboration NA61/SHINE

Primary author

Dr Nikolaos Davis (Polish Academy of Sciences (PL))


Prof. Nikolaos Antoniou (Department of Physics, University of Athens, Athens, Greece) Dr Fotios Diakonos (Department of Physics, University of Athens, Athens, Greece)

Presentation materials