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Recent results on transverse mass spectra of J/ψ and ψ ′ mesons in central Pb+Pb collisions at 158 A·GeV are considered. It is shown that those results support a hypothesis of statistical production of charmonia at hadronization and suggest the early thermal freeze-out of J/ψ and ψ ′ mesons. Based on this approach the collective transverse velocity of hadronizing quark gluon plasma is estimated to be v H T ≈ 0.2. Predictions for transverse mass spectra of hidden and open charm mesons at SPS and RHIC are discussed.Key words: statistical production of charmonia, early freeze-out, transverse flow, inverse slope parameterThe idealized concepts of chemical (hadron multiplicities) and thermal (hadron momentum distributions) freeze-outs were introduced to interpret data on hadron production in relativistic nucleus-nucleus (A+A) collisions [1]. The first experimental results on yields and transverse mass (m T = p 2 T + m 2 ) spectra suggested the following scenario: for the most abundant hadron species (π, N, K, Λ) the chemical freeze-out, which seems to coincide with the hadronization of the quark gluon plasma (QGP), is followed by the thermal freeze-out occurring at a rather late stage of the A+A reaction. In this letter we discuss whether the new data of NA50 [2] on transverse mass spectra of J/ψ and ψ ′ mesons produced in central Pb+Pb collisions at 158 A·GeV are consistent with the above picture. Our consideration is based on a recent hypothesis [3] of statistical production of charmonia at hadronization. We further suggest that thermal freeze-out of charmonia coincides with the hadronization transition. The consequences of this assumptions are in agreement with existing data on m T spectra. They allow to extract the transverse flow velocity of the hadronizing QGP and lead to new predictions which can be tested by future measurements.Rescattering among partons and, in the late stage of the reaction process, hadrons created in relativistic A+A collisions should cause local thermalization and the development of transverse collective flow of matter. Thus the final transverse motion of hadrons can be considered as a convolution of the transverse flow velocity of the freezing-out matter element with the thermal motion of the hadrons in the rest frame of this element. The resulting m T spectrum has approximately exponential shape:where C and T * are a normalization and an inverse slope parameters, respectively. The T * parameter is related to the thermal freeze-out temperature T f and the mean transverse flow velocity v f T . In the nonrelativistic approximation (m T < 2m) contributions from thermal and collective particle motions can be separated and the inverse slope parameter of the observed hadron spectrum can be expressed as [4]:Note that factor 2/π appears in Eq.(2) due to the cylindrical geometry expected in high energy A+A collisions (see [4] for details). In the case of the simultaneous thermal freeze-out of all hadrons the inverse slope parameter T * should follow the linear dependence on m given by Eq. (2). In...

Benthic foraminiferal assemblages are described for the first time from the early Eocene of West Antarctica. They come from the lower member (Telm1) of the La Meseta Formation of Isla Marambio (Seymour Island). Two distinctive assemblages, dominated by Nonionellina, Nonionella, Globocassidulina, and Eilohedra, as well as by Globocassidulina, Cribroelphidium, Guttulina, and Lobatula, indicate restricted, shallow marine, nearshore conditions. Their most characteristic species show distinct affinities with Eocene faunas of New Zealand and Patagonia, as well as with stratigraphically younger Antarctic foraminiferal communities.