Abstract
We look for fluctuations expected for the QCD critical point using an intermittency analysis in the transverse momentum phase space of protons produced around midrapidity in the 12.5\% most central C+C, Si+Si and Pb+Pb collisions at the maximum SPS energy of 158$A$~GeV. We find evidence of power-law fluctuations for the Si+Si data. The fitted power-law exponent $\phi_{2} = 0.96^{+0.38}_{-0.25}\text{ (stat.)}$ $\pm 0.16\text{ (syst.)}$ is consistent with the va\-lue expected for critical fluctuations. Power-law fluctuations had previously also been observed in low-mass $\pi^+ \pi^-$ pairs in the same Si+Si collisions.
Highlights
Theoretical investigations of the phase diagram of strongly interacting matter suggest the existence of a critical point (CP) at finite baryochemical potential and temperature
C (2015) 75:587 maximum of these fluctuation measures as a function of size and energy of the colliding ions is expected in the vicinity of the CP. Indications of such a maximum were observed in Si+Si collisions at 158 A GeV [39]. – Local power-law fluctuations [24] directly related to the critical behaviour of density-density correlations. These have been shown to be detectable [15,25] in momentum space within the framework of an intermittency analysis [40,41] through the measurement of the scaled factorial moments (SFMs) defined as: 1 Fq (M) = M D
Since the system we investigate is finite, we expect the power-law behaviour of the SFMs to hold only between two scales, dictated by the size of the system and the minimum distance of two protons in transverse momentum space [45]
Summary
Theoretical investigations of the phase diagram of strongly interacting matter suggest the existence of a critical point (CP) at finite baryochemical potential and temperature. – Local power-law fluctuations [24] directly related to the critical behaviour of density-density correlations These have been shown to be detectable [15,25] in momentum space within the framework of an intermittency analysis [40,41] through the measurement of the scaled factorial moments (SFMs) defined as:. Page 3 of 10 587 dence of the anomalous fractal dimensions dq This is due to the fact that analyzing quantities related to the order parameter of the transition in the appropriate phase space region restricts significantly the mean multiplicity of the particles carrying the critical fluctuations (protons, π +-π − pairs close to their production threshold). This analysis is a continuation of our search for indications of the CP in local density fluctuations of low-mass π +π − pairs [26]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
