856 research outputs found

    Quarkonia and heavy-flavour production in CMS

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    The Compact Muon Solenoid (CMS) has measured numerous quarkonium states via their decays into muon pairs in pp and PbPb collisions at sqrt(s_NN) = 2.76 TeV. Quarkonia are especially relevant for studying the quark-gluon plasma since they are produced at early times and propagate through the medium, mapping its evolution. Non-prompt J/psi from b-hadron decays show a strong suppression in the transverse momentum range (6.5 < p_T < 30 GeV/c) when compared to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions. This suppression is related to the in-medium b-quark energy loss. In the same kinematic region, for prompt J/psi, a strong, centrality-dependent suppression is observed in PbPb collisions. Such strong suppression at high p_T has previously not been observed at RHIC. At midrapidity (|y| < 1.6) and the same p_T region, inclusive psi(2S) are even stronger suppressed than J/psi, whereas psi(2S) at forward rapidity (1.6 < |y| < 2.4) and lower p_T (3 < p_T < 30 GeV/c) appear to be less suppressed than J/psi, however, with large uncertainties that prevent a conclusion. Furthermore, low-p_T Y(2S) and Y(3S) mesons are strongly suppressed in PbPb collisions. The suppression of the Y(1S) state is smaller than the suppression of the excited states and consistent with the suppression of the feed-down contribution only.Comment: 10 pages, 5 figures. To appear in Proc. 5th Int. Conf. on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions, Cagliari, Italy, May 27-June 1, 2012; (v2: fixed typos

    Charmonium production measured in PbPb and pp collisions by CMS

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    The Compact Muon Solenoid (CMS) is fully equipped to measure hard probes in the di-muon decay channel in the high multiplicity environment of nucleus-nucleus collisions. Such probes are especially relevant for studying the quark-gluon plasma since they are produced at early times and propagate through the medium, mapping its evolution. CMS is able to distinguish non-prompt from prompt J/psi in pp and PbPb collisions. We report here the nuclear modification factor of prompt J/psi in PbPb as a function of transverse momentum, rapidity, and the number of nucleons participating in the collision.Comment: 4 pages, 4 figures. To appear in Proc. 22nd Int. Conf. on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2011), Annecy, France, May 23-28, 201

    Measurement of the dielectron continuum in p+p and Au+Au collisions at RHIC

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    PHENIX has measured the e^+e^- pair continuum in sqrt(s_NN) = 200 GeV Au+Au and p+p collisions over a wide range of mass and transverse momenta. While the p+p data in the mass range below the phi meson are well described by known contributions from light meson decays, the Au+Au minimum bias inclusive mass spectrum shows an enhancement by a factor of 4.7 +/- 0.4(stat)} +/- 1.5(syst) +/- 0.9(model) in the mass range 0.15<m_ee<0.75 GeV/c^2. At low mass (m_ee<0.3 GeV/c^2) and high p_T (1<p_T<5~GeV/c) an enhanced e^+e^- pair yield is observed that is in qualitative agreement with hydrodynamical models of thermal photon emission with initial temperatures ranging from T_init ~= 300-600 MeV at times of 0.6-0.15 fm/c after the collision.Comment: 6 pages, 4 figures. To appear in Proc. of XLVth Rencontres de Moriond 2010 - QCD and High Energy Interactions, La Thuile, Italy, March 13-20, 201

    Upsilon suppression in PbPb collisions at the LHC

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    The Compact Muon Solenoid (CMS) has measured the suppression of the bottomonium states Y(1S), Y(2S), and Y(3S) in PbPb collisions at sqrt(s_NN) = 2.76 TeV relative to pp collisions, scaled by the number of inelastic nucleon-nucleon collisions. CMS observed a stronger suppression for the weaker bound Y(2S) and Y(3S) states than for the ground state Y(1S). Such "sequential melting" has been predicted to be a clear signature for the creation of a quark-gluon plasma. The suppression of the Y(1S) and Y(2S) has been measured as a function of collision centrality for Y in the rapidity interval |y| < 2.4 and with transverse momentum (p_T) down to 0. Furthermore, the p_T and rapidity dependence of the Y(1S) suppression are presented.Comment: 7 pages, 3 figures. To appear in Proc. 14th Int. Conf. on B-Physics at Hadron Machines (Beauty 2013), Bologna, Italy, April 8-12, 201

    Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

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    This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

    Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

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    The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe

    Severe early onset preeclampsia: short and long term clinical, psychosocial and biochemical aspects

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    Preeclampsia is a pregnancy specific disorder commonly defined as de novo hypertension and proteinuria after 20 weeks gestational age. It occurs in approximately 3-5% of pregnancies and it is still a major cause of both foetal and maternal morbidity and mortality worldwide1. As extensive research has not yet elucidated the aetiology of preeclampsia, there are no rational preventive or therapeutic interventions available. The only rational treatment is delivery, which benefits the mother but is not in the interest of the foetus, if remote from term. Early onset preeclampsia (<32 weeks’ gestational age) occurs in less than 1% of pregnancies. It is, however often associated with maternal morbidity as the risk of progression to severe maternal disease is inversely related with gestational age at onset2. Resulting prematurity is therefore the main cause of neonatal mortality and morbidity in patients with severe preeclampsia3. Although the discussion is ongoing, perinatal survival is suggested to be increased in patients with preterm preeclampsia by expectant, non-interventional management. This temporising treatment option to lengthen pregnancy includes the use of antihypertensive medication to control hypertension, magnesium sulphate to prevent eclampsia and corticosteroids to enhance foetal lung maturity4. With optimal maternal haemodynamic status and reassuring foetal condition this results on average in an extension of 2 weeks. Prolongation of these pregnancies is a great challenge for clinicians to balance between potential maternal risks on one the eve hand and possible foetal benefits on the other. Clinical controversies regarding prolongation of preterm preeclamptic pregnancies still exist – also taking into account that preeclampsia is the leading cause of maternal mortality in the Netherlands5 - a debate which is even more pronounced in very preterm pregnancies with questionable foetal viability6-9. Do maternal risks of prolongation of these very early pregnancies outweigh the chances of neonatal survival? Counselling of women with very early onset preeclampsia not only comprises of knowledge of the outcome of those particular pregnancies, but also knowledge of outcomes of future pregnancies of these women is of major clinical importance. This thesis opens with a review of the literature on identifiable risk factors of preeclampsia
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