1,429 research outputs found

    Can Recent Charge Fluctuations Be a Reliable signal for a QGP at RHIC?

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    The recent papers of Jeon and Koch [1] and Asakawa, Heinz, and Muller [2] argue that the event by event fluctuations of the ratio of the positively charged and negatively charged pions provide a distinct signal for a QGP at RHIC/LHC due to differences in those from the QGP phase and the Hadron Gas Phase.In this paper we point out that aside from the questionability of the many assumptions in the treatment used,even following their approach there are other effects not considered, e.g. color charge fluctuations, which could significantly or even completely wash out the proposed signal.Therefore lack of observation of these charge fluctuation signals cannot lead one to conclude that a QGP is not formed at RHIC. A general discussion of experimental requirements for observation of such signals(if they exist),annd how to interpret them is included.Comment: 9 pages and 2 Fig

    The Centrality Dependence of the Parton Bubble Model for high energy heavy ion collisions and fireball surface substructure at RHIC

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    In an earlier paper we developed a QCD inspired theoretical parton bubble model (PBM) for RHIC/LHC. The PBM quantitatively agreed with the strong charged particle pair correlations observed by the STAR collaboration at RHIC in the highest energy Au + Au central collisions, and also agreed with the Hanbury Brown and Twiss (HBT) observed small final state source size approximately 2f radii in the transverse momentum range above 0.8 GeV/c. The model assumed a substructure of a ring of localized adjoining 2f radius bubbles(gluonic hot spots) perpendicular to the collider beam direction, centered on the beam, at mid-rapidity and located on the expanding fireball surface of the Au + Au collisions. In this paper we extend the model (PBME) to include the changing development of bubbles with centrality from the most central region where bubbles are very important to the most peripheral where the bubbles are gone. Energy density is found to be related to bubble formation and as centrality decreases the maximum energy density and bubbles shift from symmetry around the beam axis to the reaction plane region causing a strong correlation of bubble formation with elliptic flow. We obtained reasonably quantitative agreement (within a few percent of the total correlations) with a new precision RHIC experiment which extended the centrality region investigated to the range 0-80% (most central to most peripheral). The characteristics and behavior of the bubbles imply they represent a significant substructure formed on the surface of the fireball at kinetic freezeoutComment: ACCEPTED for publication in Phys. Rev. C. minor referee changes.20 pages, 12 figures, 3 table

    Evidence for a 4th state related to the three JPC = 2++, pi- p -> phi phi n states explainable by 2++ Glueball production

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    Four separate experiments, observing the OZI forbidden disconnected reaction pi- p -> phi phi n with increasing statistics were consistent. These experiments very selectively completely broke down the OZI suppression by 3 phi phi resonances with IG JPC = 0+ 2++ in the observed mass region 2.038 to 2.600 GeV. The only viable proposed explanation has been that the IG JPC = 0+ 2++ Glueball expected in this mass region caused the hard glue in the disconnection to resonate and very selectively breakdown the OZI suppression for its quantum numbers only. Recently a p p central production spin analysis found the f2(1950) had a dominant decay mode f2(1270) pi pi. We consider if it is related to the phi phi resonances, and find that it likely is.Comment: 9 pages, 3 figure

    K∗(892)K^{*}(892) Production in Au+Au and pp Collisions at sNN\sqrt{s_{NN}} = 200GeV at STAR

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    Mid-rapidity K∗0(892)→KπK^{*0}(892)\to K\pi and K∗±(892)→KS0π±K^{*\pm}(892)\to K_S^0\pi^{\pm} are measured in Au+Au and pp collisions at sNN\sqrt{s_{NN}}=200GeV using the STAR detector at RHIC. The K∗0(892)K^{*0}(892) mass is systematically shifted at small transverse momentum for both Au+Au and pp collisions. The K∗0(892)K^{*0}(892) transverse mass spectra are measured in Au+Au collisions at different centralities and in pp collisions. The K∗0(892)K^{*0}(892) mean transverse momentum as a function of the collision centrality is compared to those of identified π−\pi^{-}, K−K^{-} and pˉ\bar{p}. The K∗/KK^{*}/K and ϕ/K∗\phi/K^{*} ratios are compared to measurements in A+A, pppp, pˉp\bar{p}p, e+e−e^{+}e^{-} collisions at various colliding energies. The physics implications of these measurements are also discussed.Comment: 6 pages, 4 figures, proceedings of Strange Quarks in Matter (SQM2003), Atlantic Beach, USA, to be published in J. Phys.

    Observing Spontaneous Strong Parity Violation in Heavy-Ion Collisions

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    We discuss the problem of observing spontaneous parity and CP violation in collision systems. We discuss and propose observables which may be used in heavy-ion collisions to observe such violations, as well as event-by-event methods to analyze the data. Finally, we discuss simple monte-carlo models of these CP violating effects which we have used to develop our techniques and from which we derive rough estimates of sensitivities to signals which may be seen at RHIC

    On Deusons or Deuteronlike Meson-Meson Bound States

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    The systematics of deuteronlike two-meson bound states, {\it deusons}, is discussed. Previous arguments that many of the present non-qqˉq\bar q states are such states are elaborated including, in particular, the tensor potential. For pseudoscalar states the important observation is made that the centrifugal barrier from the P-wave can be overcome by the 1/r21/r^2 and 1/r31/r^3 terms of the tensor potential. In the heavy meson sector one-pion exchange alone is strong enough to form at least deuteron-like BBˉ∗B\bar B^* and B∗Bˉ∗B^*\bar B^* composites bound by approximately 50 MeV, while DDˉ∗D\bar D^* and D∗Dˉ∗D^*\bar D^* states are expected near the threshold.Comment: Invited talk at the Hadron93 International Conf. on Hadron Spectroscopy, Como, Italy 22.-25.6. 1993. 5 pages in LATEX HU-SEFT R 1993-13

    Palliative care interventions for pediatric surgical patients: a systematic review.

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    Introduction There is a growing body of evidence that pediatric palli- ative care increases patient quality of life and parent sat- isfaction. Furthermore, the scope of palliative care con- tinues to expand to include complex care and coordina- tion for chronically ill children who are not necessarily approaching end of life. Many ill children with palliative needs interact with surgical providers and teams. Little is known about the utilization or efficacy of palliative care referrals for pediatric surgical patients. Material and Methods To better understand the potential need for palliative care as well as barriers to accessing care among this vulnera- ble population, we performed a systematic review of Pub- Med, EMBASE, and Cinhal for relevant literature pub- lished from January 1, 2008 to March 1, 2018. Results 10 articles met inclusion criteria. No high-quality studies were identified. Conclusion The limited available evidence suggests an unmet need for pediatric palliative care. Barriers to access were iden- tified including lack of provider palliative care education, and reluctance of the primary team to refer patients to palliative care. Further study is warranted to better guide the use of palliative care for pediatric surgical patients
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