18 research outputs found
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Au+Au reactions at the AGS: Experiments E866 and E917
Particle production and correlation functions from Au+Au reactions have been measured as a function of both beam energy (2--10.7 AGeV) and impact parameter. These results are used to probe the dynamics of heavy-ion reactions, confront hadronic models over a wide range of conditions and to search for the onset of new phenomena
Re-evaluation of the LHC potential for the measurement of Mw
We present a study of the LHC sensitivity to the W boson mass based on
simulation studies. We find that both experimental and phenomenological sources
of systematic uncertainties can be strongly constrained with Z measurements:
the lineshape is robustly predicted, and its analysis provides an accurate
measurement of the detector resolution and absolute scale, while the
differential cross-section analysis absorbs most of the strong interaction
uncertainties. A sensitivity \delta Mw \sim 7 \MeV for each decay channel (W
--> e nu, W --> mu nu), and for an integrated luminosity of 10 fb-1, appears as
a reasonable goal
Centrality and dE_{T}/d\etadN_{ch}/d\eta$ in Heavy Ion Collisions at Mid-Rapidity
The PHENIX experiment at RHIC has measured transverse energy and charged
particle multiplicity at mid-rapidity in Au + Au collisions at
= 19.6, 130, 62.4 and 200 GeV as a function of centrality. The presented
results are compared to measurements from other RHIC experiments, and
experiments at lower energies. The dependence of
and per pair of participants is consistent with logarithmic
scaling for the most central events. The centrality dependence of
and is similar at all measured incident
energies. At RHIC energies the ratio of transverse energy per charged particle
was found independent of centrality and growing slowly with . A
survey of comparisons between the data and available theoretical models is also
presented.Comment: Proccedings of the Workshop: Focus on Multiplcity at Bari, Italy,
June 17-19,2004. To be submitted to the Jornal of Physics, "Conference
series". Includes: 20 Pages, 15 figures, 3 Tables, 80 Referencie
Effective role of unpolarized nonvalence partons in Drell-Yan single spin asymmetries
We perform numerical simulations of the Sivers effect from single spin
asymmetries in Drell-Yan processes on transversely polarized protons. We
consider colliding antiprotons and pions at different kinematic conditions of
interest for the future planned experiments. We conventionally name "framework
I" the results obtained when properly accounting for the various flavor
dependent polarized valence contributions in the numerator of the asymmetry,
and for the unpolarized nonvalence contribution in its denominator. We name
"framework II" the results obtained when taking a suitable flavor average of
the valence contributions and neglecting the nonvalence ones. We compare the
two methods, also with respect to the input parametrization of the Sivers
function which is extracted from data with approximations sometimes
intermediate between frameworks I and II. Deviations between the two approaches
are found to be small except for dilepton masses below 3 GeV. The Sivers effect
is used as a test case; the arguments can be generalized to other interesting
azimuthal asymmetries in Drell-Yan processes, such as the Boer-Mulders effect.Comment: 13 pages, 9 figures in eps forma
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Antiproton production in 11.7 AGeV/c Au+Au collisions from E866
We present antiproton production in 11.7 AGeV/c Au+Au collisions measured in a wide transverse-mass coverage from the AGS-E866 experiment. We show indications for strong absorption effects of antiprotons in Au+Au collisions through comparison with p+A and Si+A collisions, and centrality dependence in Au+Au collisions
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Azimuthal asymmetry of particle production in Au + Au collisions at 11.6 A{center_dot}GeV/c
Particle production was measured by the E866 forward spectrometer. It was reported earlier in our publication that a correlation between particle ratios and the asymmetry of energy deposition in zero degree calorimeter(ZCAL) was found. To further investigate the azimuthal asymmetry analysis, the forward hodoscope (HODO) was incorporated and the correlation between the particle production and the ``reaction plane`` will be discussed. Preliminary analysis shows enhanced in- plain proton production
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Hadronic spectra in Au+Au reactions at 11.6 A{center_dot}GeV/c: Rapidity and m{sub t} distributions
In central Au+Au collisions, the rapidity distribution of measured protons integrated over {ital m{sub t}} indicates almost complete stopping, hence high baryon density. For a given rapidity, low mt enhancement has been observed for {pi}{sup -} production over that of {pi}{sup +}. The Coulomb interaction with the co-moving medium has been invoked to explain the difference. The inverse slope parameters of the {ital m{sub t}} spectra for protons and deuterons increases from peripheral to central events, while the parameter for pions stays the same. This may indicate that a radial expansion follows the high density stage of the reaction
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Transverse momentum dependent two-pion Bose-Einstein correlations in Au + Au collisions at 11.6 A {center_dot} GeV/c
Bose-Einstein correlations of {pi}{sup +}{pi}{sup +} and {pi}{sup {minus}}{pi}{sup {minus}} pairs collected by the BNL-E866 Forward Spectrometer in 11.6 A{center_dot}GeV/c Au + Au collisions have been measured. The data were analyzed using three-dimensional correlation functions parameterized by the Yano-Koonin-Potgoretskii and Bertsch-Pratt formalism to study transverse momentum dependent source parameters. Rapid decreases of longitudinal source radii and slower decreases in the transverse parameters with increasing transverse momentum were observed, which suggests a strong longitudinal and some transverse expansion. A freeze-out time {tau}{sub 0} was derived as 4.5--5 fm/c, under the assumption of the freeze-out temperature T = 130 MeV, and the duration of emission was found to be {delta}{tau} {approx} 2--4 fm/c