Heavy Quarkonia in Quark-Gluon Plasma

Using the color-singlet free energy F_1 and total internal energy U_1 obtained by Kaczmarek et al. for a static quark Q and an antiquark Qbar in quenched QCD, we study the binding energies and wave functions of heavy quarkonia in a quark-gluon plasma. By minimizing the grand potential in a simplified schematic model, we find that the proper color-singlet Q-Qbar potential can be obtained from the total internal energy U_1 by subtracting the gluon internal energy contributions. We carry out this subtraction in the local energy-density approximation in which the gluon energy density can be related to the local gluon pressure by the quark-gluon plasma equation of state. We find in this approximation that the proper color-singlet Q-Qbar potential is approximately F_1 for T ~ T_c and it changes to (3/4)F_1+(1/4)U_1 at high temperatures. In this potential model, the J/psi is weakly bound above the phase transition temperature T_c, and it dissociates spontaneously above 1.62 T_c, while chi_c and psi' are unbound in the quark-gluon plasma. The bottomium states Upsilon, chi_b and Upsilon' are bound in the quark-gluon plasma and they dissociate at 4.10 T_c, 1.18 T_c, and 1.38 T_c respectively. For comparison, we evaluate the heavy quarkonium binding energies also in other models using the free energy F_1 or the total internal energy U_1 as the Q-Qbar potential. The comparison shows that the model with the new Q-Qbar potential proposed in this manuscript gives dissociation temperatures that agree best with those from spectral function analyses. We evaluate the cross section for sigma(g+J/psi->c+cbar) and its inverse process, in order to determine the J/psi dissociation width and the rate of J/psi production by recombining c and cbar in the quark gluon plasma.Comment: 30 pages, in Late

Effects of Parton Intrinsic Transverse Momentum on Photon Production in Hard-Scattering Processes

We calculate the photon production cross section arising from the hard scattering of partons in nucleon-nucleon collisions by taking into account the intrinsic parton transverse momentum distribution and the next-to-leading-order contributions. As first pointed out by Owens, the inclusion of the intrinsic transverse momentum distribution of partons leads to an enhancement of photon production cross section in the region of photon transverse momenta of a few GeV/c for nucleon-nucleon collisions at a center-of-mass energy of a few tens of GeV. The enhancement increases as $\sqrt{s}$ decreases. Such an enhancement is an important consideration in the region of photon momenta under investigation in high-energy heavy-ion collisions.Comment: 10 pages, 9 figures, in LaTex, revised to include ananlytic evaluation of the hard-scattering integra

Endoscopic Management of Gastric Polyp with Outlet Obstruction without Polypectomy

Although gastric polyp is usually an incidental endoscopic finding, large-sized polyps can cause symptoms ranging from epigastralgia to bleeding from ulcerated polyps and gastric outlet obstruction. Although the gold standard of treatment is removal of the polyp either through endoscopic polypectomy or surgical excision, complications associated with these procedures cannot be ignored. The risk becomes a major concern for patients at high risk for surgery when complications arise. We describe a debilitated 74-year-old woman who presented with early satiety, intermittent postprandial nausea and vomiting for three months. Upper endoscopy revealed a 2.5 cm pedunculated polyp over the gastric antrum causing intermittent obstruction. Considering her high risk for polypectomy, detachable snaring was performed without polypectomy in an outpatient setting. The patient was complication-free with complete relief of obstructive symptoms one week after the procedure. Subsequent follow-ups showed satisfactory healing without signs of mucosal disruption or recurrence. The results suggest that detachable snaring without polypectomy may be a therapeutic option for high-risk patients with benign symptomatic gastric polyps

Inclusive and Direct Photons in S + Au Central Collisions at 200A GeV/c

A hadron and string cascade model, JPCIAE, which is based on LUND string model, PYTHIA event generator especially, is used to study both inclusive photon production and direct photon production in 200A GeV S + Au central collisions. The model takes into account the photon production from the partonic QCD scattering process, the hadronic final-state interaction, and the hadronic decay and deals with them consistently. The results of JPCIAE model reproduce successfully both the WA93 data of low p_T inclusive photon distribution and the WA80 data of transverse momentum dependent upper limit of direct photon. The photon production from different decay channels is investigated for both direct and inclusive photons. We have discussed the effects of the partonic QCD scattering and the hadronic final-state interaction on direct photon production as well.Comment: 6 pages with 5 figure

Feynman diagrams versus Fermi-gas Feynman emulator

Precise understanding of strongly interacting fermions, from electrons in modern materials to nuclear matter, presents a major goal in modern physics. However, the theoretical description of interacting Fermi systems is usually plagued by the intricate quantum statistics at play. Here we present a cross-validation between a new theoretical approach, Bold Diagrammatic Monte Carlo (BDMC), and precision experiments on ultra-cold atoms. Specifically, we compute and measure with unprecedented accuracy the normal-state equation of state of the unitary gas, a prototypical example of a strongly correlated fermionic system. Excellent agreement demonstrates that a series of Feynman diagrams can be controllably resummed in a non-perturbative regime using BDMC. This opens the door to the solution of some of the most challenging problems across many areas of physics

Medical interventions for treating anthracycline-induced symptomatic and asymptomatic cardiotoxicity during and after treatment for childhood cancer

Anthracyclines are frequently used chemotherapeutic agents for childhood cancer that can cause cardiotoxicity during and after treatment. Although several medical interventions in adults with symptomatic or asymptomatic cardiac dysfunction due to other causes are beneficial, it is not known if the same treatments are effective for childhood cancer patients and survivors with anthracycline-induced cardiotoxicity. To compare the effect of medical interventions on anthracycline-induced cardiotoxicity in childhood cancer patients or survivors with the effect of placebo, other medical interventions or no treatment. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2011, issue 1), MEDLINE/PubMed (1949 to May 2011) and EMBASE/Ovid (1980 to May 2011) for potentially relevant articles. We additionally searched reference lists of relevant articles, conference proceedings and ongoing trial databases. Randomised controlled trials (RCTs) or controlled clinical trials (CCTs) comparing the effectiveness of medical interventions to treat anthracycline-induced cardiotoxicity with either placebo, other medical interventions or no treatment. Two review authors independently performed the study selection. One review author performed the data extraction and 'Risk of bias' assessments which were checked by another review author. We identified two RCTs. One trial (135 patients) compared enalapril with placebo in childhood cancer survivors with asymptomatic anthracycline induced cardiac dysfunction. The other trial (68 patients) compared a two-week treatment of phosphocreatine with a control treatment (vitamin C, ATP, vitamin E, oral coenzyme Q10) in leukaemia patients with anthracycline-induced cardiotoxicity. Both studies had methodological limitations.The RCT on enalapril showed no (statistically) significant differences in overall survival, mortality due to heart failure, development of clinical heart failure and quality of life between treatment and control group. A post-hoc analysis showed a decrease (i.e. improvement) in one measure of cardiac function (left ventricular end systolic wall stress (LVESWS): -8.62% change) compared with placebo (+1.66% change) in the first year of treatment (P = 0.036), but not afterwards. Patients treated with enalapril had a higher risk of dizziness or hypotension (RR 7.17, 95% CI 1.71 to 30.17) and fatigue (Fisher's exact test, P = 0.013).The RCT on phosphocreatine found no differences in overall survival, mortality due to heart failure, echocardiographic cardiac function and adverse events between treatment and control group. For the effect of enalapril in childhood cancer survivors with asymptomatic cardiac dysfunction, only one RCT is available. Although there is some evidence that enalapril temporarily improves one parameter of cardiac function (LVESWS), it is unclear whether it improves clinical outcomes. Enalapril was associated with a higher risk of dizziness or hypotension and fatigue. Clinicians should weigh the possible benefits with the known side-effects of enalapril in childhood cancer survivors with asymptomatic anthracycline-induced cardiotoxicity.For the effect of phosphocreatine in childhood cancer patients with anthracycline-induced cardiotoxicity, only one RCT is available. Limited data with a high risk of bias showed no significant difference between phosphocreatine and control treatment on echocardiographic function and clinical outcomes.We did not identify any RCTs or CCTs studying other medical interventions for symptomatic or asymptomatic cardiotoxicity in childhood cancer patients or survivors.High-quality studies should be performe

Anomalous J/psi suppression and charmonium dissociation cross sections

We study $J/\psi$ suppression in Pb+Pb collisions at CERN-SPS energies in hadronic matter with energy- and temperature-dependent charmonium dissociation cross sections calculated in the quark-interchange model of Barnes and Swanson. We find that the variation of J/$\psi$ survival probability from peripheral to central collisions can be explained as induced by hadronic matter absorption in central collisions.Comment: 30 pages, 8 figures, LaTex, changed for the latest NA50 dat

Correction Factors for Reactions involving Quark-Antiquark Annihilation or Production

In reactions with $q \bar q$ production or $q\bar q$ annihilation, initial- and final-state interactions give rise to large corrections to the lowest-order cross sections. We evaluate the correction factor first for low relative kinetic energies by studying the distortion of the relative wave function. We then follow the procedure of Schwinger to interpolate this result with the well-known perturbative QCD vertex correction factors at high energies, to obtain an explicit semi-empirical correction factor applicable to the whole range of energies. The correction factor predicts an enhancement for $q\bar q$ in color-singlet states and a suppression for color-octet states, the effect increasing as the relative velocity decreases. Consequences on dilepton production in the quark-gluon plasma, the Drell-Yan process, and heavy quark production processes are discussed.Comment: 25 pages (REVTeX), includes 2 uuencoded compressed postscript figure