16,443 research outputs found

    Hadronization via Coalescence

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    We review the quark coalescence model for hadronization in relativistic heavy ion collisions and show how it can explain the observed large baryon to meson ratio at intermediate transverse momentum and scaling of the elliptic flows of identified hadrons. We also show its predictions on higher-order anisotropic flows and discuss how quark coalescence applied to open- and hidden-charm mesons can give insight to charm quark interactions in the quark-gluon plasma and J/ΨJ/\Psi production in heavy ion collisions.Comment: 6 pages, 4 figures, Proceedings of 20th Winter Workshop on Nuclear Dynamics, Trelawny Beach, Jamaica, March 15--20, 200

    Transport properties of isospin effective mass splitting

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    We investigate in detail the momentum dependence (MDMD) of the effective in medium Nucleon-Nucleon (NNNN) interaction in the isovector channel. We focus the discussion on transport properties of the expected neutron-proton (n/pn/p) effective mass splitting at high isospin density. We look at observable effects from collective flows in Heavy Ion Collisions (HICHIC) of charge asymmetric nuclei at intermediate energies. Using microscopic kinetic equation simulations nucleon transverse and elliptic collective flows in Au+AuAu+Au collisions are evaluated. In spite of the reduced charge asymmetry of the interacting system interesting isospinMDisospin-MD effects are revealed. Good observables, particularly sensitive to the n/pn/p-mass splitting, appear to be the differences between neutron and proton flows. The importance of more exclusive measurements, with a selection of different bins of the transverse momenta (ptp_t) of the emitted particles, is stressed. In more inclusive data a compensation can be expected from different ptp_t-contributions, due to the microscopic isospinMDisospin-MD structure of the nuclear mean field in asymmetric matter.Comment: 18 pages, 11 figure

    Safe discontinuation of nilotinib in a patient with chronic myeloid leukemia: a case report

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    Case presentation. We report the case of a 64-year-old Caucasian man diagnosed with chronic-phase chronic myeloid leukemia in April 2005. After 4 years of treatment with imatinib, he became intolerant to the drug and was switched to nilotinib. Two years later, he decided to stop nilotinib. Undetectable molecular response persisted for 30 months after discontinuation of the drug. Introduction. Although there is a considerable amount of data in the literature on safe discontinuation of first-generation tyrosine kinase inhibitor therapy in patients with chronic myeloid leukemia, little is known about discontinuation of second-generation tyrosine kinase inhibitor therapy. Most previous studies have been focused on dasatinib, and the few cases of nilotinib withdrawal that have been reported had a median follow-up of 12 months. To the best of our knowledge, the present report is the first to describe nilotinib withdrawal with 30 months of follow-up. Conclusion: Our present case suggests that nilotinib withdrawal is safe for patients with chronic myeloid leukemia who achieve a stable undetectable molecular response. Our patient was homozygous for killer immunoglobulin-like receptor haplotype A, previously reported to be a promising immunogenetic marker for undetectable molecular response. We recommend additional studies to investigate patient immunogenetic profiles and their potential role in complete response to therap

    Scalings of Elliptic Flow for a Fluid at Finite Shear Viscosity

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    Within a parton cascade approach we investigate the scaling of the differential elliptic flow v2(pT)v_2(p_T) with eccentricity ϵx\epsilon_x and system size and its sensitivity to finite shear viscosity. We present calculations for shear viscosity to entropy density ratio η/s\eta/s in the range from 1/4π1/4\pi up to 1/π1/\pi, finding that the v2v_2 saturation value varies by about a factor 2. Scaling of v2(pT)/ϵxv_2(p_T)/\epsilon_x is seen also for finite η/s\eta/s which indicates that it does not prove a perfect hydrodynamical behavior, but is compatible with a plasma at finite η/s\eta/s. Introducing a suitable freeze-out condition, we see a significant reduction of v2(pT)v_2(p_T) especially at intermediate pTp_T and for more peripheral collisions. This causes a breaking of the scaling for both v2(pT)v_2(p_T) and the pTp_T-averaged v2v_2, while keeping the scaling of v_2(p_T)/\la v_2\ra. This is in better agreement with the experimental observations and shows as a first indication that the η/s\eta/s should be significantly lower than the pQCD estimates. We finally point out the necessity to include the hadronization via coalescence for a definite evaluation of η/s\eta/s from intermediate pTp_T data.Comment: 5 pages, 5 figures. Two points in fig.4 has been change

    Impact of temperature dependence of the energy loss on jet quenching observables

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    The quenching of jets (particles with pT>>T,ΛQCDp_T>>T, \Lambda_{QCD}) in ultra-relativistic heavy-ion collisions has been one of the main prediction and discovery at RHIC. We have studied, by a simple jet quenching modeling, the correlation between different observables like the nuclear modification factor \Rapt, the elliptic flow v2v_2 and the ratio of quark to gluon suppression RAA(quark)/RAA(gluon)R_{AA}(quark)/R_{AA}(gluon). We show that the relation among these observables is strongly affected by the temperature dependence of the energy loss. In particular the large v2v_2 and and the nearly equal \Rapt of quarks and gluons can be accounted for only if the energy loss occurs mainly around the temperature TcT_c and the flavour conversion is significant.Finally we point out that the efficency in the conversion of the space eccentricity into the momentum one (v2v_2) results to be quite smaller respect to the one coming from elastic scatterings in a fluid with a viscosity to entropy density ratio 4πη/s=14\pi\eta/s=1.Comment: 7 pages, 8 figures, Workshop WISH 201

    Asymptotic robustness of Kelly's GLRT and Adaptive Matched Filter detector under model misspecification

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    A fundamental assumption underling any Hypothesis Testing (HT) problem is that the available data follow the parametric model assumed to derive the test statistic. Nevertheless, a perfect match between the true and the assumed data models cannot be achieved in many practical applications. In all these cases, it is advisable to use a robust decision test, i.e. a test whose statistic preserves (at least asymptotically) the same probability density function (pdf) for a suitable set of possible input data models under the null hypothesis. Building upon the seminal work of Kent (1982), in this paper we investigate the impact of the model mismatch in a recurring HT problem in radar signal processing applications: testing the mean of a set of Complex Elliptically Symmetric (CES) distributed random vectors under a possible misspecified, Gaussian data model. In particular, by using this general misspecified framework, a new look to two popular detectors, the Kelly's Generalized Likelihood Ration Test (GLRT) and the Adaptive Matched Filter (AMF), is provided and their robustness properties investigated.Comment: ISI World Statistics Congress 2017 (ISI2017), Marrakech, Morocco, 16-21 July 201