Search results for "Experiments"
showing 10 items of 435 documents
Precision Measurement of the Mass and Lifetime of the Ξ[0 over b] Baryon
2014
Using a proton-proton collision data sample corresponding to an integrated luminosity of 3 fb$^{-1}$ collected by LHCb at center-of-mass energies of 7 and 8 TeV, about 3800 $\Xi_b^0\to\Xi_c^+\pi^-$, $\Xi_c^+\to pK^-\pi^+$ signal decays are reconstructed. From this sample, the first measurement of the $\Xi_b^0$ baryon lifetime is made, relative to that of the $\Lambda_b^0$ baryon. The mass differences $M(\Xi_b^0)-M(\Lambda_b^0)$ and $M(\Xi_c^+)-M(\Lambda_c^+)$ are also measured with precision more than four times better than the current world averages. The resulting values are $\frac{\tau_{\Xi_b^0}}{\tau_{\Lambda_b^0}} = 1.006\pm0.018\pm0.010$, $M(\Xi_b^0) - M(\Lambda_b^0) = 172.44\pm0.39\pm…
Measurement of D-meson production versus multiplicity in p-Pb collisions at √SNN = 5.02 TeV
2016
The measurement of prompt D-meson production as a function of multiplicity in p–Pb collisions at √ sNN = 5.02 TeV with the ALICE detector at the LHC is reported. D0 , D+ and D∗+ mesons are reconstructed via their hadronic decay channels in the centre-of-mass rapidity range −0.96 < ycms < 0.04 and transverse momentum interval 1 < pT < 24 GeV/c. The multiplicity dependence of D-meson production is examined by either comparing yields in p–Pb collisions in different event classes, selected based on the multiplicity of produced particles or zero-degree energy, with those in pp collisions, scaled by the number of binary nucleon-nucleon collisions (nuclear modification factor); as well as by evalu…
Measurement of D0, D+, D*+ and Ds+ production in Pb-Pb collisions at √sNN = 5.02 TeV
2018
We report measurements of the production of prompt D0, D+, D*+ and D s + mesons in Pb–Pb collisions at the centre-of-mass energy per nucleon-nucleon pair sNN−−−√=5.02 TeV, in the centrality classes 0–10%, 30–50% and 60–80%. The D-meson production yields are measured at mid-rapidity (|y| 8 GeV/c, while it is larger at lower pT. The nuclear modification factors for strange and non-strange D mesons are also compared to theoretical models with different implementations of in-medium energy loss. peerReviewed
Measurements of low-pT electrons from semileptonic heavy-flavour hadron decays at mid-rapidity in pp and Pb-Pb collisions at √sNN = 2.76 TeV
2018
Transverse-momentum (pT) differential yields of electrons from semileptonic heavy-flavour hadron decays have been measured in the most central (0–10%) and in semi-central (20–40%) Pb–Pb collisions at √sNN=2.76 TeV. The corresponding production cross section in pp collisions has been measured at the same energy with substantially reduced systematic uncertainties with respect to previously published results. The modification of the yield in Pb–Pb collisions with respect to the expectation from an incoherent superposition of nucleon-nucleon collisions is quantified at mid-rapidity (|y| < 0.8) in the pT interval 0.5–3 GeV/c via the nuclear modification factor, RAA. This paper extends the pT rea…
Λc+ production in pp collisions at √s = 7 TeV and in p-Pb collisions at √sNN = 5.02 TeV
2018
The pT-differential production cross section of prompt Λ+ c charmed baryons was measured with the ALICE detector at the Large Hadron Collider (LHC) in pp collisions at √ s = 7 TeV and in p-Pb collisions at √ sNN = 5.02 TeV at midrapidity. The Λ+ c and Λ– c were reconstructed in the hadronic decay modes Λ+ c → pK−π +, Λ+ c → pK0 S and in the semileptonic channel Λ+ c → e +νeΛ (and charge conjugates). The measured values of the Λ + c /D0 ratio, which is sensitive to the c-quark hadronisation mechanism, and in particular to the production of baryons, are presented and are larger than those measured previously in different colliding systems, centre-of-mass energies, rapidity and pT intervals, w…
Amplitude analysis and branching-fraction measurement of D-s(+) -> K-S(0)pi(+)pi(0)
2022
Journal of high energy physics 2021(6), 181 (2021). doi:10.1007/JHEP06(2021)181
Measurement of inclusive charged-particle b-jet production in pp and p-Pb collisions at √sNN = 5.02 TeV
2022
A measurement of the inclusive b-jet production cross section is presented in pp and p-Pb collisions at √sNN = 5.02 TeV, using data collected with the ALICE detector at the LHC. The jets were reconstructed in the central rapidity region |η| < 0.5 from charged particles using the anti-kT algorithm with resolution parameter R = 0.4. Identification of b jets exploits the long lifetime of b hadrons, using the properties of secondary vertices and impact parameter distributions. The pT-differential inclusive production cross section of b jets, as well as the corresponding inclusive b-jet fraction, are reported for pp and p-Pb collisions in the jet transverse momentum range 10 ≤ pT,ch jet≤ 100 GeV…
Measurement of the spin of the Xi(1530) resonance
2008
The properties of the Xi(1530) resonance are investigated in the Lambdac+ --> Xi- pi+ K+ decay process. The data sample was collected with the BaBar detector at the SLAC PEP-II asymmetric-energy e+ e- collider operating at center of mass energies 10.58 and 10.54 GeV. The corresponding integrated luminosity is approximately 230 inverse fb. The spin of the Xi(1530) is established to be 3/2. The existence of an S-wave amplitude in the Xi- pi+ system is inferred, and its interference with the Xi(1530)0 amplitude provides the first clear demonstration of the Breit-Wigner phase motion expected for the Xi(1530). The P_1(cos[theta(Xi-)]) Legendre polynomial moment indicates the presence of a sig…
Measurement of the Mass Difference m(B0) - m(B+)
2008
Using 230 million B Bbar events recorded with the BABAR detector at the e+ e- storage rings PEP-II, we reconstruct approximately 4100 B0 to J/psi K+ pi- and 9930 B+ to J/psi K+ decays with J/psi to mu+ mu- and e+ e-. From the measured B-momentum distributions in the e+ e- rest frame, we determine the mass difference m(B0) - m(B+) = (+0.33 +- 0.05 +- 0.03) MeV/c^2.
Rate capability of a cryogenic stopping cell for uranium projectile fragments produced at 1000 MeV/u
2016
At the Low-Energy Branch (LEB) of the Super-FRS at FAIR, projectile and fission fragments will be produced at relativistic energies, separated in-flight, energy-bunched, slowed down and thermalized in a cryogenic stopping cell (CSC) filled with ultra-pure He gas. The fragments are extracted from the stopping cell using a combination of DC and RF electric fields and gas flow. A prototype CSC for the LEB has been developed and successfully commissioned at the FRS Ion Catcher at GSI. Ionization of He buffer gas atoms during the stopping of energetic ions creates a region of high space charge in the stopping cell. The space charge decreases the extraction efficiency of stopping cells since the …