| 1. |
- Abelev, Betty, et al.
(författare)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :11
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Tidskriftsartikel (refereegranskat)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 2. |
- Abelev, Betty, et al.
(författare)
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Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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| 3. |
- Brugaletta, Salvatore, et al.
(författare)
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Morphology of coronary artery lesions assessed by virtual histology intravascular ultrasound tissue characterization and fractional flow reserve
- 2012
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Ingår i: The International Journal of Cardiovascular Imaging. - : Springer Science and Business Media LLC. - 1569-5794 .- 1875-8312 .- 1573-0743. ; 28:2, s. 221-228
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Tidskriftsartikel (refereegranskat)abstract
- Fractional flow reserve (FFR) is an index of the physiological significance of a coronary stenosis. Patients who have lesions with a FFR of >0.80, even optimally treated with medication, have however a MACE rate ranging from 8 to 21%. Coronary plaques at high risk of rupture and clinical events can be also identified by virtual histology intravascular ultrasound (IVUS-VH) as plaques with high amount of necrotic core (NC) abutting the lumen. Aim of this exploratory study was to investigate whether the geometry and composition of lesions with FFR ≤ 0.80 were different from their counterparts. Fifty-five consecutive patients in whom FFR was clinically indicated on a moderate angiographic lesion, received also an imaging investigation on the same lesion with IVUS-VH. Data on plaque geometry and composition was analyzed. Patients were subdivided in two groups according to the value of FFR (> or ≤0.80). Lesions with a FFR ≤ 0.80 (n = 17) showed a slightly larger plaque burden than those with FFR > 0.80 (n = 38) (54.6 ± 0.7% vs. 51.7 ± 0.7% P = 0.1). In addition, they tend to have less content of necrotic core than their counterparts (14.2 ± 8% vs. 19.2 ± 10.2%, P = 0.08). No difference was found in the distribution of NC-rich plaques (fibroatheroma and thin-capped fibroatheroma) between groups (82% in FFR ≤ 0.80 vs. 79% in FFR > 0.80, P = 0.5). Although FFR ≤ 0.80 lesions have larger plaque size, they do not differ in composition from the ones with FFR > 0.80. Further exploration in a large prospective study is needed to study whether the lesions with FFR > 0.80 that are NC rich are the ones associated with the presence of clinical events at follow-up.
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