45 research outputs found

    Quons Restricted to the Antisymmetric Subspace: Formalism and Applications

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    In this work we develop a formalism to treat quons restricted to the antisymmetric part of their many-body space. A model in which a system of identical quons interact through a pairing force is then solved within this restriction and the differences between our solution and the usual fermionic model solution are then presented and discussed in detail. Possible connections to physical systems are also considered.Comment: 12 pages, 3 figure

    Non-Abelian dynamics and heavy multiquarks, Steiner-tree confinement in hadron spectroscopy

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    A brief review is first presented of attempts to predict stable multiquark states within current models of hadron spectroscopy. Then a model combining flip-flop and connected Steiner trees is introduced and shown to lead to stable multiquarks, in particular for some configurations involving several heavy quarks and bearing exotic quantum numbers.Comment: 8 pages, 5 figures, Invited talk at the 21st European Conference on Few-Body Problems in Physics, Salamanca, Spain, August 29th--September 3rd, 2010, to appear in the Proceedings, ed.~A.~Valcarce et al., to appear in Few-Body Syste

    Cranked Relativistic Hartree-Bogoliubov Theory: Superdeformed Bands in the A190A\sim 190 Region

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    Cranked Relativistic Hartree-Bogoliubov (CRHB) theory is presented as an extension of Relativistic Mean Field theory with pairing correlations to the rotating frame. Pairing correlations are taken into account by a finite range two-body force of Gogny type and approximate particle number projection is performed by Lipkin-Nogami method. This theory is applied to the description of yrast superdeformed rotational bands observed in even-even nuclei of the A190A\sim 190 mass region. Using the well established parameter sets NL1 for the Lagrangian and D1S for the pairing force one obtains a very successful description of data such as kinematic (J(1)J^{(1)}) and dynamic (J(2)J^{(2)}) moments of inertia without any adjustment of new parameters. Within the present experimental accuracy the calculated transition quadrupole moments QtQ_t agree reasonably well with the observed data.Comment: 6 pages including 4 PostScript figures, uses RevTex, revised version, Phys.Rev. C, Rapid Communications, in pres

    Energy and system size dependence of \phi meson production in Cu+Cu and Au+Au collisions

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    We study the beam-energy and system-size dependence of \phi meson production (using the hadronic decay mode \phi -- K+K-) by comparing the new results from Cu+Cu collisions and previously reported Au+Au collisions at \sqrt{s_NN} = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented are from mid-rapidity (|y|<0.5) for 0.4 < pT < 5 GeV/c. At a given beam energy, the transverse momentum distributions for \phi mesons are observed to be similar in yield and shape for Cu+Cu and Au+Au colliding systems with similar average numbers of participating nucleons. The \phi meson yields in nucleus-nucleus collisions, normalised by the average number of participating nucleons, are found to be enhanced relative to those from p+p collisions with a different trend compared to strange baryons. The enhancement for \phi mesons is observed to be higher at \sqrt{s_NN} = 200 GeV compared to 62.4 GeV. These observations for the produced \phi(s\bar{s}) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems.Comment: 20 pages and 5 figure

    Evidence of psi(3770) non-DD-bar Decay to J/psi pi+pi-

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    Evidence of ψ(3770)\psi(3770) decays to a non-DDˉ{D \bar D} final state is observed. A total of 11.8±4.8±1.311.8 \pm 4.8 \pm 1.3 \psi(3770) \to \PPJP events are obtained from a data sample of 27.7 pb1\rm {pb^{-1}} taken at center-of-mass energies around 3.773 GeV using the BES-II detector at the BEPC. The branching fraction is determined to be BF(\psi(3770) \to \PPJP)=(0.34\pm 0.14 \pm 0.09)%, corresponding to the partial width of \Gamma(\psi(3770) \to \PPJP) = (80 \pm 33 \pm 23) keV.Comment: 8 pages, 7 figures, Submitted to Physics Letters

    Ks0^0_sKs0^0_s correlations in pp collisions at s=7\sqrt{s}=7 TeV from the LHC ALICE experiment

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    Identical neutral kaon pair correlations are measured in s=7\sqrt{s}=7 TeV pp collisions in the ALICE experiment. One-dimensional Ks0^0_sKs0^0_s correlation functions in terms of the invariant momentum difference of kaon pairs are formed in two multiplicity and two transverse momentum ranges. The femtoscopic parameters for the radius and correlation strength of the kaon source are extracted. The fi{\rm i}t includes quantum statistics and final-state interactions of the a0_0/f0_0 resonance. Ks0^0_sKs0^0_s correlations show an increase in radius for increasing multiplicity and a slight decrease in radius for increasing transverse mass, mTm_{\rm T}, as seen in ππ\pi\pi correlations in the pp system and in heavy-ion collisions. Transverse mass scaling is observed between the Ks0^0_sKs0^0_s and ππ\pi\pi radii. Also, the fi{\rm i}rst observation is made of the decay of the f2_2'(1525) meson into the Ks0^0_sKs0^0_s channel in pp collisions.Comment: 17 pages, 7 captioned figures, 2 tables, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/310

    Effects of rare kidney diseases on kidney failure: a longitudinal analysis of the UK National Registry of Rare Kidney Diseases (RaDaR) cohort

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    Background Individuals with rare kidney diseases account for 5–10% of people with chronic kidney disease, but constitute more than 25% of patients receiving kidney replacement therapy. The National Registry of Rare Kidney Diseases (RaDaR) gathers longitudinal data from patients with these conditions, which we used to study disease progression and outcomes of death and kidney failure. Methods People aged 0–96 years living with 28 types of rare kidney diseases were recruited from 108 UK renal care facilities. The primary outcomes were cumulative incidence of mortality and kidney failure in individuals with rare kidney diseases, which were calculated and compared with that of unselected patients with chronic kidney disease. Cumulative incidence and Kaplan–Meier survival estimates were calculated for the following outcomes: median age at kidney failure; median age at death; time from start of dialysis to death; and time from diagnosis to estimated glomerular filtration rate (eGFR) thresholds, allowing calculation of time from last eGFR of 75 mL/min per 1·73 m2 or more to first eGFR of less than 30 mL/min per 1·73 m2 (the therapeutic trial window). Findings Between Jan 18, 2010, and July 25, 2022, 27 285 participants were recruited to RaDaR. Median follow-up time from diagnosis was 9·6 years (IQR 5·9–16·7). RaDaR participants had significantly higher 5-year cumulative incidence of kidney failure than 2·81 million UK patients with all-cause chronic kidney disease (28% vs 1%; p<0·0001), but better survival rates (standardised mortality ratio 0·42 [95% CI 0·32–0·52]; p<0·0001). Median age at kidney failure, median age at death, time from start of dialysis to death, time from diagnosis to eGFR thresholds, and therapeutic trial window all varied substantially between rare diseases. Interpretation Patients with rare kidney diseases differ from the general population of individuals with chronic kidney disease: they have higher 5-year rates of kidney failure but higher survival than other patients with chronic kidney disease stages 3–5, and so are over-represented in the cohort of patients requiring kidney replacement therapy. Addressing unmet therapeutic need for patients with rare kidney diseases could have a large beneficial effect on long-term kidney replacement therapy demand. Funding RaDaR is funded by the Medical Research Council, Kidney Research UK, Kidney Care UK, and the Polycystic Kidney Disease Charity

    Study of the KS0KS0 final state in two-photon collisions

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    Delayed improvement in exercise capacity after cardioversion of atrial fibrillation to sinus rhythm.

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    In some patients symptoms improve after the restoration of sinus rhythm from atrial fibrillation. To assess the size and mechanism of such change, exercise capacity and pulsed Doppler left ventricular inflow velocities were assessed in 20 patients with established atrial fibrillation. Treadmill exercise capacity was assessed by measuring maximal oxygen consumption and anaerobic threshold before and on day 1 and 28 days after elective DC cardioversion. The relative contribution of atrial contraction to left ventricular filling was determined by relating the maximum height of the A wave to the maximum height of the E wave (A/E) of the Doppler velocity time curve. Cardioversion was successful in 14 patients. Maximal oxygen consumption and anaerobic threshold were unchanged on day 1 and increased by day 28 in all 14 patients. The percentage improvement was inversely related to the baseline values; however, the absolute improvement was small in all patients. The mean A/E ratio increased significantly from day 1 to day 28 in all 14 patients. Thus the restoration of sinus rhythm was associated with a delayed improvement in exercise capacity that may in part be due to a slow improvement in atrial contractility and peak cardiac output after cardioversion
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