Search results for "Collider"
showing 10 items of 1690 documents
Cross section forbb¯production via dielectrons ind+ Au collisions atsNN=200GeV
2015
We report a measurement of e+e− pairs from semileptonic heavy-flavor decays in d+Au collisions at sNN−−−√=200 GeV. By exploring the mass and transverse-momentum dependence of the yield, the bottom decay contribution can be isolated from charm, and quantified by comparison to pythia and mc@nlo simulations. The resulting bb¯-production cross section is σdAubb¯=1.37±0.28(stat)±0.46(syst) mb, which is equivalent to a nucleon-nucleon cross section of σNNbb=3.4±0.8(stat)±1.1(syst)μb.
Search for a heavy Standard Model Higgs boson in the channel H→ZZ→ℓ+ℓ−qq¯ using the ATLAS detector
2012
A search for a heavy Standard Model Higgs boson decaying via H -> ZZ -> l(+)l(-)q (q) over bar, where l = e, mu, is presented. The search is performed using a data set of pp collisions at root s = 7 TeV, corresponding to an integrated luminosity of 1.04 fb(-1) collected in 2011 by the ATLAS detector at the CERN LHC collider. No significant excess of events above the estimated background is found. Upper limits at 95% confidence level on the production cross section (relative to that expected from the Standard Model) of a Higgs boson with a mass in the range between 200 and 600 GeV are derived. Within this mass range, there is at present insufficient sensitivity to exclude a Standard Model Hi…
New results on hyperon decays from NA48
2001
In 1999 the NA48 experiment at CERN had two short data taking periods (8h and 40h) with a high intensity KS beam. Together with the KS mesons a large number of neutral hyperons, e.g. Λ and Ξ0, are produced. During these periods a large sample of Ξ0 decays was collected. About 115,000 events of the decay mode Ξ0 → Λπ0, about 500 of Ξ0 → Λγ, about 400 of Ξ0 → Σ0γ and about 60 events of Ξ0 → Σ+ e have been reconstructed. The status of the analyses of the above decay modes is presented.
A NEW MEASUREMENT OF DIRECT CP VIOLATION IN K→ππ DECAYS BY THE NA48 EXPERIMENT AT CERN
2001
A new measurement of ℛe(∊′/∊) by the NA48 collaboration using data collected in 1998 is presented. The preliminary result is ℛe(∊'/∊) =(12.2±2.9 ( stat )±4.0 ( sys )) ×10-4. The combination with the previous measurement using the 1997 data yields ℛe(∊′/∊)=(14.0±4.3)×10-4. This result confirms the existence of direct CP violation. The uncertainty on this measurement will be improved in the future.
Nucleon structure functions from deep inelastic muon scattering
1992
Abstract Recent experimental results from the CERN NA37 (NMC) experiment on deep inelastic muon scattering on hydrogen and deuterium are presented. Absolute structure functions have been measured at 90 and 280 GeV incident energy covering the kinematical range 0.006 2 2 . The new results help to resolve the severe discrepancies between the data of the previous experiments. In addition data on the structure function ratio F 2 n /F 2 p are reviewed. Evidence for a non-leading twist at × ⪆ 0.20 is extracted from the Q 2 dependence of the structure function ratio. Its effect on the determination of the Gottfried sum rule is discussed.
Measurement of the lifetime of theBc+meson using theBc+→J/ψπ+decay mode
2015
The difference in total widths between the B+c and B+ mesons is measured using 3.0fb−1 of data collected by the LHCb experiment in 7 and 8 TeV centre-of-mass energy proton-proton collisions at the LHC. Through the study of the time evolution of B+c→J/ψπ+ and B+→J/ψK+ decays, the width difference is measured to beΔΓ≡ΓB+c−ΓB+=4.46±0.14±0.07mm−1c,where the first uncertainty is statistical and the second systematic. The known lifetime of the B+ meson is used to convert this to a precise measurement of the B+c lifetime,τB+c=513.4±11.0±5.7fs,where the first uncertainty is statistical and the second systematic.
Suppression of ϒ(1S) at forward rapidity in Pb–Pb collisions at sNN=2.76 TeV
2014
We report on the measurement of the inclusive Υ (1S) production in Pb–Pb collisions at √sNN = 2.76 TeV carried out at forward rapidity (2.5 < y < 4) and down to zero transverse momentum using its μ+μ− decay channel with the ALICE detector at the Large Hadron Collider. A strong suppression of the inclusive Υ (1S) yield is observed with respect to pp collisions scaled by the number of independent nucleon– nucleon collisions. The nuclear modification factor, for events in the 0–90% centrality range, amounts to 0.30 ± 0.05(stat) ± 0.04(syst). The observed Υ (1S) suppression tends to increase with the centrality of the collision and seems more pronounced than in corresponding mid-rapidity measur…
Coherent and incoherent (μ−, e−) conversion in nuclei
1993
Coherent and incoherent (μ−, e−) conversion in nuclei is studied within the framework of several theories which violate flavour lepton number. A useful approach is followed which allows a factorization of the conversion widths into nuclear factors and other factors which depend only on the elementary process. The nuclear factors are evaluated in a wide range of nuclei allowing simple calculations of the conversion rates throughout the periodic table for a given theory with a minimum of work in the elementary sector. The coherent conversion is found to dominate the process. The results obtained modify appreciable previous results in the literature, particularly in the incoherent process.
Single-Neutron States inS133n
1996
The location of several single-neutron states in ${}^{133}\mathrm{Sn}$ has been identified. The ${p}_{3/2}$, ${h}_{9/2}$, and ${f}_{5/2}$ states were found at 853.7, 1560.9, and 2004.6 keV, respectively, by measuring $\ensuremath{\gamma}$ rays in coincidence with delayed neutrons following the decay of ${}^{134}\mathrm{In}$. Crucial for obtaining the new data were the improved yields at the mass-separator facility ISOLDE-PSB at CERN. A semiempirically adjusted Woods-Saxon calculation, based on parameters from the Pb region and normalized on the mass data at ${}^{132}\mathrm{Sn}$, reproduces the new single particle energies with good precision.
Exclusive Vector Meson Production at the EIC
2020
We discuss how vector meson production at the future Electron Ion Collider can be used to probe non-linear dynamics in heavy nuclei. Additionally, the potential to study the evolution of proton and nuclear geometries with event-by-event fluctuations is illustrated.