Abstract In a systematic search for the QCD critical point in nuclear collisions, at the CERN SPS, it was found that intermittency measurements in the freeze-out state of central Si + Si collisions, at the maximum SPS energy, provide us with an indication of sizeable critical fluctuations. Also, rather recently, a weaker effect was traced in preliminary data of the Ar + Sc reaction for 10–20% most central collisions at (approximately) the same energy. However, the uncertainties in the analysis and the limitations of the experimental event statistics make the interpretation of the above measurements (NA49, NA61/SHINE) rather inconclusive, inviting for a further, phenomenological investigation with complementary tools and theoretical ideas. To this end, in the present work, we employ intermittency techniques within a model-independent analysis scheme (AMIAS), a novel method from Data Science [1] , in order to produce unbiased results for the parameters of the power-laws and in particular for the associated power-law exponent (intermittency index) ϕ 2 . Using data-sets at different peripheralities, we also study the dependence of the ϕ 2 -value on the number of wounded nucleons, in order to uncover the approach to the critical point. With these findings and the help of Ising-QCD partition function, the interpretation of SPS intermittency measurements and their links to the critical region, are discussed.
We investigate the D_{s0}^\ast(2317)meson using lattice QCD and considering correlation functions of several \bar{c} stwo-quark and \bar{c} s (\bar{u} u + \bar{d} d)four-quark interpolating fields. These interpolating fields generate different structures in color, spin and position space including quark-antiquark pairs, tetraquarks and two-meson scattering states. For our computation we use an ensemble simulated with pion mass m_\pi \approx 0.296 \, \textrm{GeV}and spatial volume of ...
We employ the recently introduced Ising-QCD partition function (N.~G. Antoniou {\it et al.}, Phys. Rev. D 97, 034015 (2018)) to explore in detail the behaviour of the moments of the baryon-number, within the critical region around the critical endpoint. Our analysis is based on the relation of finite-size scaling in real space with intermittency in transverse momentum space. It demonstrates in practice the recent observation (N.~G. Antoniou {\it et al.}, Phys. Rev. D 97, 034015 (2018)) that comb...
The multipole content of pion photoproduction at the \Delta^{+}(1232) resonance has been extracted from a data set dominated by recent Mainz Microtron (MAMI) precision measurements. The analysis has been carried out in the Athens Model Independent Analysis Scheme (AMIAS), thus eliminating any model bias. The benchmark quantity for nucleon deformation, EMR = E2/M1 = E1+3/2/M1+3/2, was determined to be -2.5±0.4stat+syst, thus reconfirming in a model independent way that the conjecture of baryon...
#2Fotios K. Diakonos(UoA: National and Kapodistrian University of Athens)H-Index: 13
#3X. N. Maintas(UoA: National and Kapodistrian University of Athens)H-Index: 6
Last. C. E. Tsagkarakis(UoA: National and Kapodistrian University of Athens)H-Index: 5
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Considering the 3d Ising universality class of the QCD critical endpoint we use a universal effective action for the description of the baryon-number density fluctuations around the critical region. Calculating the baryon-number multiplicity moments and determining their scaling with system's size we show that the critical region is very narrow in the direction of the baryon chemical potential \muand wide in the temperature direction Tfor T > T_c In this context, published experimental ...
We show that critical systems of finite size develop a fractal structure in momentum space with anomalous dimension given in terms of the isotherm critical exponent delta of the corresponding infinite system. The associated power laws of transverse momentum correlations, in high-energy nuclear collisions, provide us with a signature of a critical point in strongly interacting matter according to the laws of QCD.
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 158A 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 value expected for critical fl...
#2Marcus Bleicher(FIAS: Frankfurt Institute for Advanced Studies)H-Index: 67
Last. Reinhard Stock(Goethe University Frankfurt)H-Index: 18
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We present an analysis of hadronic multiplicities measured in Pb-Pb collisions at {\sqrt{s}}_{NN}=2.76TeV as a function of the collision centrality within the statistical hadronization model. Evidence is found of a dependence of the chemical freeze-out temperature as a function of centrality, with a slow rise from central to peripheral collisions, which we interpret as an effect of posthadronization inelastic scatterings. Using correction factors calculated by means of a simulation based on t...
#2K. P. Marinova(JINR: Joint Institute for Nuclear Research)H-Index: 4
Abstract The present table contains experimental root-mean-square (rms) nuclear charge radii R obtained by combined analysis of two types of experimental data: (i) radii changes determined from optical and, to a lesser extent, K α X-ray isotope shifts and (ii) absolute radii measured by muonic spectra and electronic scattering experiments. The table combines the results of two working groups, using respectively two different methods of evaluation, published in ADNDT earlier. It presents an updat...
Pion production in nuclear collisions at the Super Proton Synchrotron (SPS) is investigated with the aim to search, in a restricted domain of the phase diagram, for power laws in the behavior of correlations that are compatible with critical QCD. We analyzed interactions of nuclei of different sizes (p+p, C+C, Si+Si, Pb+Pb) at 158A GeV adopting, as appropriate observables, scaled factorial moments in a search for intermittent fluctuations in transverse dimensions. The analysis is performed for π...
We show that critical opalescence, a clear signature of second-order phase transition in conventional matter, manifests itself as critical intermittency in QCD matter produced in experiments with nuclei. This behavior is revealed in transverse momentum spectra as a pattern of power laws in factorial moments, to all orders, associated with baryon production. This phenomenon together with a similar effect in the isoscalar sector of pions (sigma mode) provide us with a set of observables associated...
