3,558 research outputs found
Reaction of benzylchlorocarbene with hydrogen chloride
No full textPT: J; CR: BROWN HC, 1942, J AM CHEM SOC, V64, P2223 BUSSEY RJ, 1969, J ORG CHEM, P1323 CLOSS GL, 1962, J AM CHEM SOC, V84, P4350 COCIVERA M, 1963, J AM CHEM SOC, V85, P1702 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 KIRMSE W, 1971, CARBENE CHEM LIU MTH, 1981, J CHEM SOC P2, P53 LIU MTH, 1982, CHEM SOC REV, V11, P127 LIU MTH, 1984, J CHEM SOC CHEM COMM, P1062 LIU MTH, 1984, TETRAHEDRON, V40, P887 MOSS RA, 1973, CARBENES, V1 MOSS RA, 1975, CARBENES, V2; NR: 12; TC: 5; J9: J ORG CHEM; PG: 3; GA: APQ51Source type: Electronic(1
Measurement of sigma B-chi c2(chi(c2)-> J/psi gamma)/sigma B-chi c1(chi(c1)-> J/psi gamma) in p(p)over-bar collisions at root s=1.96 TeV
No full textWe measure the ratio of cross section times branching fraction, R-p=sigma B-chi c2(chi(c2)-> J/psi gamma)/sigma B-chi c1(chi(c1)-> J/psi gamma), in 1.1 fb(-1) of p (p) over bar collisions at root s=1.96 TeV. This measurement covers the kinematic range p(T)(J/psi)> 4.0 GeV/c, |eta(J/psi) 1.0 GeV/c. For events due to prompt processes, we find R-p=0.395 +/- 0.016(stat)+/- 0.015(syst). This result represents a significant improvement in precision over previous measurements of prompt chi(c1,2) hadro production
Polarizations of J/psi and psi(2S) mesons produced in p(p)over-bar collisins at root s-1.96 TeV
No full textWe have measured the polarizations of J/psi and psi(2S) mesons as functions of their transverse momentum p(T) when they are produced promptly in the rapidity range |y|= 5 GeV/c. The analysis is performed using a data sample with an integrated luminosity of about 800 pb(-1) collected by the CDF II detector. For both vector mesons, we find that the polarizations become increasingly longitudinal as p(T) increases from 5 to 30 GeV/c. These results are compared to the predictions of nonrelativistic quantum chromodynamics and other contemporary models. The effective polarizations of J/psi and psi(2S) mesons from B-hadron decays are also reported
A Presentation of the Groups PSL(2, <i>p</i>)
No full textIn the present paper, we shall prove the following result.Theorem A. The groups PSL(2, p) can be presented by the following system of generators and relations:1.1This theorem considerably improves earlier results of Bussey, Frasch, and Todd (cf. 2, pp. 93-96). The presentation of Frasch reads as follows:1.2</jats:p
Intact negative patterning in rats with fornix or combined perirhinal and postrhinal cortex lesions
No full textIt has been proposed that the hippocampal formation is necessary for the acquisition of tasks that require the use of configural representations for their solution, including spatial learning and negative patterning. Tests of this influential view have, however, yielded conflicting results. For example fornix or hippocampal lesions, which reliably impair spatial learning, do not reliably impair negative patterning. A problem in interpreting these results has been the lack of controls for factors such as over-responding, excitatory effects of reward, and the possibility of non-configural solutions. At the same time, other studies have pointed to a role in configural learning for parahippocampal regions such as the perirhinal cortex. The present experiments controlled for the above factors and revealed that neither lesions of the fornix nor of the perirhinal/postrhinal cortex in the rat had any effect on negative patterning, although subsequent tests of object and spatial memory demonstrated the functional efficacy of the lesions
Measurement of the cross-section ratio in exclusive photoproduction at HERA
No full textThe exclusive photoproduction reactions and
have been measured at an centre-of-mass energy
of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 373
pb. The measurement was made in the kinematic range GeV,
GeV and GeV, where is the photon--proton
centre-of-mass energy, is the photon virtuality and is the squared
four-momentum transfer at the proton vertex. The decay channels used were
, and with subsequent decay . The
ratio of the production cross sections, , has been measured as a function of and and
compared to previous data in photoproduction and deep inelastic scattering and
with predictions of QCD-inspired models of exclusive vector-meson production,
which are in reasonable agreement with the data.Comment: 31 pages, 9 figures. Updated according to comments from journal
referee including a new table. Added full collaboration author lis
Measurement of the J/psi meson and b-hadron production cross sections in p(p)over-bar collisions at root s=1960 GeV
No full textWe present a new measurement of the inclusive and differential production cross sections of J/psi mesons and b hadrons in proton-antiproton collisions at roots=1960 GeV. The data correspond to an integrated luminosity of 39.7 pb(-1) collected by the CDF run II detector. We find the integrated cross section for inclusive J/psi production for all transverse momenta from 0 to 20 GeV/c in the rapidity range |y|\u3c0.6 to be 4.08+/-0.02(stat)(-0.33)(+0.36)(syst) mub. We separate the fraction of J/psi events from the decay of the long-lived b hadrons using the lifetime distribution in all events with p(T)(J/psi)\u3e1.25 GeV/c. We find the total cross section for b hadrons, including both hadrons and antihadrons, decaying to J/psi with transverse momenta greater than 1.25 GeV/c in the rapidity range |y(J/psi)|\u3c0.6 is 0.330+/-0.005(stat)(-0.033)(+0.036)(syst) mub. Using a Monte Carlo simulation of the decay kinematics of b hadrons to all final states containing a J/psi, we extract the first measurement of the total single b-hadron cross section down to zero transverse momentum at roots=1960 GeV. We find the total single b-hadron cross section integrated over all transverse momenta for b hadrons in the rapidity range |y|\u3c0.6 to be 17.6+/-0.4(stat)(-2.3)(+2.5)(syst) mub
Measurement of the cross-section for the reaction gamma p ---> J / psi p with the ZEUS detector at HERA
No full textThis paper reports the cross section measurements for the process ep --> e J/psi p for Q(2) < 4 GeV2 at root s = 296 GeV, based on an integrated luminosity of about 0.5 pb(-1), using the ZEUS detector. The J/psi was detected in its e(+)e(-) and mu(+)mu(-) decay modes. The photoproduction cross section was measured to be 52(-12)(+7) +/- 10 nb at an average gamma p centre of mass energy of 67 GeV and 71(-20)(+13) +/- 12 nb at 114 GeV. The significant rise of the cross section compared to lower energy measurements is not in agreement with VDM models, but can be described by QCD inspired models if a rise in the gluon momentum density at low x in the proton is assumed
Measurement of the Lambda(0)(b) lifetime in Lambda(0)(b)-> J/psi Lambda(0) in p(p)over-bar collisions at root s=1.96 TeV
No full textWe report a measurement of the Lambda(0)(b) lifetime in the exclusive decay Lambda(0)(b)-> J/psi Lambda(0) in p (p) over bar collisions at root s=1.96 TeV using an integrated luminosity of 1.0 fb(-1) of data collected by the CDF II detector at the Fermilab Tevatron. Using fully reconstructed decays, we measure tau(Lambda(0)(b))=1.593(-0.078)(+0.083)(stat)+/- 0.033(syst) ps. This is the single most precise measurement of tau(Lambda(0)(b)) and is 3.2 sigma higher than the current world average
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