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In high-energy heavy-ion collisions, partonic collectivity is evidenced by the constituent quark number scaling of elliptic flow anisotropy for identified hadrons. A breaking of this scaling and dominance of baryonic interactions is found for identified hadron collective flow measurements in √sNN = 3 GeV Au+Au collisions. In this paper, we report measurements of the first- and second-order azimuthal anisotropic parameters, v1 and v2, of light nuclei (d, t, 3He, 4He) produced in √sNN = 3 GeV Au+Au collisions at the STAR experiment. An atomic mass number scaling is found in the measured v1 slopes of light nuclei at mid-rapidity. For the measured v2 magnitude, a strong rapidity dependence is observed. Unlike v2 at higher collision energies, the v2 values at mid-rapidity for all light nuclei are negative and no scaling is observed with the atomic mass number. Calculations by the Jet AA Microscopic Transport Model (JAM), with baryonic mean-field plus nucleon coalescence, are in good agreement with our observations, implying baryonic interactions dominate the collective dynamics in 3 GeV Au+Au collisions at RHIC.
Measurement of cold nuclear matter effects for inclusive J/ψ in p+Au collisions at √sNN = 200 GeV
(2022)
Measurement by the STAR experiment at RHIC of the cold nuclear matter (CNM) effects experienced by inclusive J/ψ at mid-rapidity in 0-100% p+Au collisions at √sNN = 200 GeV is presented. Such effects are quantified utilizing the nuclear modification factor, RpAu, obtained by taking a ratio of J/ψ yield in p+Au collisions to that in p+p collisions scaled by the number of binary nucleon-nucleon collisions. The differential J/ψ yield in both p+p and p+Au collisions is measured through the dimuon decay channel, taking advantage of the trigger capability provided by the Muon Telescope Detector in the RHIC 2015 run. Consequently, the J/ψ RpAu is derived within the transverse momentum (pT) range of 0 to 10 GeV/c. A suppression of approximately 30% is observed for pT < 2 GeV/c, while J/ψ RpAu becomes compatible with unity for pT greater than 3 GeV/c, indicating the J/ψ yield is minimally affected by the CNM effects at high pT. Comparison to a similar measurement from 0-20% central Au+Au collisions reveals that the observed strong J/ψ suppression above 3 GeV/c is mostly due to the hot medium effects, providing strong evidence for the formation of the quark-gluon plasma in these collisions. Several model calculations show qualitative agreement with the measured J/ψ RpAu, while their agreement with the J/ψ yields in p+p and p+Au collisions is worse.
We report the first multi-differential measurements of strange hadrons of K −, φ and − yields as well as the ratios of φ/K − and φ/− in Au+Au collisions at √sNN = 3 GeV with the STAR experiment fixed target configuration at RHIC. The φ mesons and − hyperons are measured through hadronic decay channels, φ → K + K − and Ξ− → Λπ−. Collision centrality and rapidity dependence of the transverse momentum spectra for these strange hadrons are presented. The 4π yields and ratios are compared to thermal model and hadronic transport model predictions. At this collision energy, thermal model with grand canonical ensemble (GCE) under-predicts the φ/K − and φ/− ratios while the result of canonical ensemble (CE) calculations reproduce φ/K −, with the correlation length rc ∼ 2.7 fm, and φ/−, rc ∼ 4.2 fm, for the 0-10% central collisions. Hadronic transport models including high mass resonance decays could also describe the ratios. While thermal calculations with GCE work well for strangeness production in high energy collisions, the change to CE at 3 GeV implies a rather different medium property at high baryon density.
We report on the measurements of directed flow v1 and elliptic flow v2 for hadrons (π±, K ±, K0 S , p, φ, Λ and ) from Au+Au collisions at √sN N = 3 GeV and v2 for (π±, K ±, p and p) at 27 and 54.4 GeV with the STAR experiment. While at the two higher energy midcentral collisions the numberof-constituent-quark (NCQ) scaling holds, at 3 GeV the v2 at midrapidity is negative for all hadrons and the NCQ scaling is absent. In addition, the v1 slopes at midrapidity for almost all observed hadrons are found to be positive, implying dominant repulsive baryonic interactions. The features of negative v2 and positive v1 slope at 3 GeV can be reproduced with a baryonic mean-field in transport model calculations. These results imply that the medium in such collisions is likely characterized by baryonic interactions.
Jameson argues that in 'a society bereft of all historicity', 'what used to be the historical novel can no longer set out to represent the historical past'. The 'postmodern fate' of the historical novel is to be forced to come to terms with 'a new and original historical situation in which we are condemned to seek History by way of our own pop images and simulacra of that history, which itself remains forever out of reach. Salman Rushdie's "Midnight's Children" (1981) and Patrick Süskind's "Das Parfum. Die Geschichte eines Mörders" (1984) stand out as two hugely successful novels from this period that raise questions about historical representation within the space of the popular. They might therefore be used as test cases for Jameson's concerns. "Midnight's Children" is a sprawling story of Indian and British imperial and post-imperial history across the twentieth century. "Das Parfum" tells the tightly framed tale of a murderous perfumer in eighteenth-century France. Seemingly very different texts, they bear one curious similarity: both feature a protagonist with an unusually sensitive sense of smell.
In his article "The End of History?", originally published in the journal "The National Interest" in Summer 1989, Frances Fukuyama argued that 'the triumph of the West, of the Western idea, is evident first of all in the total exhaustion of viable systemic alternatives to Western liberalism.' It was in this respect that history had reached its 'end': the course of history in the sense of 'mankind's logical evolution' had arrived at 'the universalization of Western liberal democracy as the final form of human government'. [...] A look at some of the historical fiction written in the 1980s might suggest ways out of this potential imaginative impasse, offering up alternative possibilities, or 'Gegenwelten', in place of the dispiriting spectacle of history-on-repeat. Fukuyama himself does not mention literature. In fact, the historical fiction of the 1980s reveals a space in which the meaning of 'history' is still very much contested and where the threat of the 'end of history' in its more obvious sense - in the form of nuclear war or climate apocalypse - emerges as a force that speaks powerfully to the anxiety of our present moment. Two evocative novels that have much to tell us in these respects are Christa Wolf's "Kassandra" and Jeanette Winterson's "Sexing the Cherry". Published in 1984 and 1989, these two texts challenged the idea of rational progress and 'mankind's logical evolution' by raising the prospect of a distinctive feminist poetics - of 'écriture féminine' and 'what it will do' as Hélène Cixous had put it in her 1975 essay "The Laugh of the Medusa". The 'Gegenwelten' they propose suggest ways out of the macho strait jacket of violence, destruction and impending nuclear war.