Achievements and challenges in intermittency analysis

29 maja 2024 roku o godzinie 13:15 w sali 143 odbędzie się seminarium Instytutu Fizyki, na którym
Dr. Nikolaos Davis z Instytut Fizyki Jądrowej im. Henryka Niewodniczańskiego Polskiej Akademii Nauk
wygłosi referat pt.: „Achievements and challenges in intermittency analysis”.

Abstract:
The search for experimental signatures of the critical point (CP) of
strongly interacting matter is one of the main objectives of numerous
heavy ion collision experiments today, including NA61/SHINE and STAR.
In the vicinity of the CP, a strongly interacting matter system
experiences a second-order phase transition and can be described in a
scale-invariant way; consequently, fluctuations of the transition
order parameter constitute ideal observables for the detection of the
CP and are expected to scale according to universal power-laws.
Candidates for the role of order parameter include the net baryon
density $n_B$, as well as the $\sigma$-condensate; it can be
experimentally probed by studying the multiplicity fluctuations of
protons or reconstructed pion pairs (dipions) as a function of bin
size in transverse momentum space – a method known as intermittency
analysis of the scaled factorial moments.
Intermittency analysis, as commonly practiced up to now (e.g. on NA49
/ SHINE / STAR heavy ion collisions) faces considerable challenges; on
the one hand, due to sometimes limited event statistics and/or low
multiplicity of identified particles, uncertainties can be large,
leading to inconclusive results; and on the other hand, the fact that
values corresponding to different scales are correlated complicates
estimation of uncertainties. In my talk, I give a full account of
these challenges in past and current analyses and present the
statistical techniques recently developed in order to provide robust
solutions. I employ extensive Monte Carlo simulations in order to
reliably determine the requirements for a successful intermittency
analysis, in terms of event statistics, event multiplicity, and
particle identification efficiency. Finally, I discuss the extent to
which these challenges, relevant to numerous state-of-the-art
datasets, could be overcome with future high-statistics measurements.