A measurement of Υ suppression in Au-Au collisions at 200 GeV in the PHENIX experiment

Upsilon production was measured in Au-Au collisions using the PHENIX detector at RHIC using the data taken during the 2010 data taking operations. It was found that Upsilon production was suppressed relative to proton-proton collisions

Multiple predator effects and native prey responses to two non-native Everglades cichlids

Abstract -Non-native predators may have negative impacts on native communities, and these effects may be dependent on interactions among multiple non-native predators. Sequential invasions by predators can enhance risk for native prey. Prey have a limited ability to respond to multiple threats since appropriate responses may conflict, and interactions with recent invaders may be novel. We examined predator-prey interactions among two non-native predators, a recent invader, the African jewelfish, and the longer-established Mayan cichlid, and a native Florida Everglades prey assemblage. Using field enclosures and laboratory aquaria, we compared predatory effects and antipredator responses across five prey taxa. Total predation rates were higher for Mayan cichlids, which also targeted more prey types. The cichlid invaders had similar microhabitat use, but varied in foraging styles, with African jewelfish being more active. The three prey species that experienced predation were those that overlapped in habitat use with predators. Flagfish were consumed by both predators, while riverine grass shrimp and bluefin killifish were eaten only by Mayan cichlids. In mixed predator treatments, we saw no evidence of emergent effects, since interactions between the two cichlid predators were low. Prey responded to predator threats by altering activity but not vertical distribution. Results suggest that prey vulnerability is affected by activity and habitat domain overlap with predators and may be lower to newly invading predators, perhaps due to novelty in the interaction

Audiovisual Metadata Platform Pilot Development (AMPPD), Final Project Report

This report documents the experience and findings of the Audiovisual Metadata Platform Pilot Development (AMPPD) project, which has worked to enable more efficient generation of metadata to support discovery and use of digitized and born-digital audio and moving image collections. The AMPPD project was carried out by partners Indiana University Libraries, AVP, University of Texas at Austin, and New York Public Library between 2018-2021

Heavy-quark production and elliptic flow in Au plus Au collisions at root(NN)-N-S=62.4 GeV

We present measurements of electrons and positrons from the semileptonic decays of heavy-flavor hadrons at midrapidity (vertical bar gamma vertical bar \u3c 0.35) in Au + Au collisions at root(NN)-N-S = 62.4 GeV. The data were collected in 2010 by the PHENIX experiment that included the new hadron-blind detector. The invariant yield of electrons from heavy-flavor decays is measured as a function of transverse momentum in the range 1 \u3c p(T)(e) \u3c 5 GeV/c. The invariant yield per binary collision is slightly enhanced above the p + p reference in Au + Au 0%-20%, 20%-40%, and 40%-60% centralities at a comparable level. At this low beam energy this may be a result of the interplay between initial-state Cronin effects, final-state flow, and energy loss in medium. The v(2) of electrons from heavy-flavor decays is nonzero when averaged between 1.3 \u3c p(T)(e) \u3c 2.5 GeV/c for 0%-40% centrality collisions at root(NN)-N-S = 62.4 GeV. For 20%-40% centrality collisions, the v(2) at root(NN)-N-S = 62.4 GeV is smaller than that for heavy-flavor decays at root(NN)-N-S = 200 GeV. The v2 of the electrons from heavy-flavor decay at the lower beam energy is also smaller than v(2) for pions. Both results indicate that the heavy quarks interact with the medium formed in these collisions, but they may not be at the same level of thermalization with the medium as observed at root(NN)-N-S = 200 GeV

Centrality dependence of low-momentum direct-photon production in Au plus Au collisions at root s(NN)=200 GeV

The PHENIX experiment at RHIC has measured the centrality dependence of the direct photon yield from Au + Au collisions at root s(NN) = 200 GeV down to pT = 0.4 GeV/c. Photons are detected via photon conversions to e(+)e(-) pairs and an improved technique is applied that minimizes the systematic uncertainties that usually limit direct photon measurements, in particular at low pT. We find an excess of direct photons above the N-coll-scaled yield measured in p + p collisions. This excess yield is well described by an exponential distribution with an inverse slope of about 240 MeV/c in the pT range 0.6-2.0 GeV/c. While the shape of the pT distribution is independent of centrality within the experimental uncertainties, the yield increases rapidly with increasing centrality, scaling approximately with N-part(alpha), where alpha = 1.38 +/- 0.03(stat) +/- 0.07(syst)

Measurement of gamma(1S+2S+3S) production in p plus p and Au plus Au collisions at root sNN=200 GeV

Measurements of bottomonium production in heavy-ion and p + p collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The inclusive yield of the three states, (1S + 2S + 3S), was measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au + Au and p + p collisions at root sNN = 200 GeV. The (1S + 2S + 3S) -\u3e e(+)e(-) differential cross section at midrapidity was found to be B(ee)d sigma/dy = 108 +/- 38 (stat) +/- 15 (syst) +/- 11 (luminosity) pb in p + p collisions. The nuclear modification factor in the 30% most central Au + Au collisions indicates a suppression of the total. state yield relative to the extrapolation from p + p collision data. The suppression is consistent with measurements made by STAR at RHIC and at higher energies by the CMS experiment at the Large Hadron Collider

Measurements of double-helicity asymmetries in inclusive J/Psi production in longitudinally polarized p plus p collisions at root s=510 GeV

We report the double-helicity asymmetry, A(LL)(J/Psi), in inclusive J/Psi production at forward rapidity as a function of transverse momentum p(T) and rapidity |y|. The data analyzed were taken during root s = 510 GeV longitudinally polarized p + p collisions at the Relativistic Heavy Ion Collider in the 2013 run using the PHENIX detector. At this collision energy, J/Psi particles are predominantly produced through gluon-gluon scatterings, thus A(LL)(J/Psi) is sensitive to the gluon polarization inside the proton. We measured A(LL)(J/Psi) by detecting the decay daughter muon pairs mu(+)mu(-) within the PHENIX muon spectrometers in the rapidity range 1.2 \u3c |y| \u3c 2.2. In this kinematic range, we measured the A(LL)(J/Psi) to be 0.012 +/- 0.010 (stat) +/- 0.003 (syst). The A(LL)(J.Psi) can be expressed to be proportional to the product of the gluon polarization distributions at two distinct ranges of Bjorken x: one at moderate range x approximate to 5 x 10(-2) where recent data of jet and pi(0) double helicity spin asymmetries have shown evidence for significant gluon polarization, and the other one covering the poorly known small-x region x approximate to 2 x 10(-3). Thus our new results could be used to further constrain the gluon polarization for x \u3c 5 x 10(-2)

Inclusive cross section and double-helicity asymmetry for pi(0) production at midrapidity in p plus p collisions at root s=510 GeV

PHENIX measurements are presented for the cross section and double-helicity asymmetry (A(LL)) in inclusive pi(0) production at midrapidity from p + p collisions at root s = 510 GeV from data taken in 2012 and 2013 at the Relativistic Heavy Ion Collider. The next-to-leading-order perturbative-quantum-chromodynamics theory calculation is in excellent agreement with the presented cross section results. The calculation utilized parton-to-pion fragmentation functions from the recent DSS14 global analysis, which prefer a smaller gluon-to-pion fragmentation function. The pi(0)A(LL) results follow an increasingly positive asymmetry trend with p(T) and root s with respect to the predictions and are in excellent agreement with the latest global analysis results. This analysis incorporated earlier results on pi(0) and jet A(LL) and suggested a positive contribution of gluon polarization to the spin of the proton Delta G for the gluon momentum fraction range x \u3e 0.05. The data presented here extend to a currently unexplored region, down to x similar to 0.01, and thus provide additional constraints on the value of Delta G