Giacomo Margagliotti | Università degli Studi di Trieste (original) (raw)

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Papers by Giacomo Margagliotti

Physics Letters B, 2016

The production of the hypertriton nuclei 3 Λ H and 3 Λ H has been measured for the first time in ... more The production of the hypertriton nuclei 3 Λ H and 3 Λ H has been measured for the first time in Pb-Pb collisions at √ s NN = 2.76 TeV with the ALICE experiment at LHC. The p T-integrated 3 Λ H yield in one unity of rapidity, dN/dy ×B.R. (3 Λ H→ 3 He,π −) = (3.86 ± 0.77(stat.) ± 0.68(syst.)) × 10 −5 in the 0-10% most central collisions, is consistent with the predictions from a statistical thermal model using the same temperature as for the light hadrons. The coalescence parameter B 3 shows a dependence on the transverse momentum, similar to the B 2 of deuterons and the B 3 of 3 He nuclei. The ratio of yields S 3 = 3 Λ H/(3 He×Λ/p) was measured to be S 3 = 0.60 ± 0.13 (stat.) ± 0.21 (syst.) in 0-10% centrality events; this value is compared to different theoretical models. The measured S 3 is compatible with thermal model predictions. The measured 3 Λ H lifetime, τ = 181 +54 −39 (stat.) ± 33(syst.) ps is in agreement within 1σ with the world average value.

Physics Letters B, 2018

√ s NN = 5.02 TeV, respectively. Both the jet energy and the jet mass are expected to be sensitiv... more √ s NN = 5.02 TeV, respectively. Both the jet energy and the jet mass are expected to be sensitive to jet quenching in the hot Quantum Chromodynamics (QCD) matter created in nuclear collisions at collider energies. Jets are reconstructed from charged particles using the anti-k T jet algorithm and resolution parameter R = 0.4. The jets are measured in the pseudorapidity range |η jet | < 0.5 and in three intervals of transverse momentum between 60 GeV/c and 120 GeV/c. The measurement of the jet mass in central Pb-Pb collisions is compared to the jet mass as measured in p-Pb reference collisions, to vacuum event generators, and to models including jet quenching. It is observed that the jet mass in central Pb-Pb collisions is consistent within uncertainties with p-Pb reference measurements. Furthermore, the measured jet mass in Pb-Pb collisions is not reproduced by the quenching models considered in this letter and is found to be consistent with PYTHIA expectations within systematic uncertainties.

Journal of Physics: Conference Series, 2013

Heavy quarks are produced in early partonic hard scatterings and experience the full history of a... more Heavy quarks are produced in early partonic hard scatterings and experience the full history of a heavy-ion collision. Consequently heavy quarks are a good tool to study properties of the hot and dense medium. In proton-proton collisions, the study of the production of heavy quarks provides an important test for perturbative QCD and serves as a reference for heavy ion collisions. Heavy-flavour measurements in the semi-electronic channel are performed with ALICE at midrapidity. We present the measurement of the pT-differential cross section in proton-proton collisions at √ s = 7 TeV, and of the nuclear modification factor and elliptic flow in Pb-Pb collisions at √ sNN = 2.76 TeV.

The European Physical Journal C, 2013

Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions... more Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass M X < 200 GeV/c 2) σ SD /σ INEL = 0.21 ± 0.03, 0.20 +0.07 −0.08 , and 0.20 +0.04 −0.07 , respectively at centre-of-mass energies √ s = 0.9, 2.76, and 7 TeV; for double diffraction (for a pseudorapidity gap η > 3) σ DD /σ INEL = 0.11 ± 0.03, 0.12 ± 0.05, and 0.12 +0.05 −0.04 , respectively at √ s = 0.9, 2.76, and 7 TeV. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: σ INEL = 62.8 +2.4 −4.0 (model) ± 1.2(lumi) mb at √ s = 2.76 TeV and 73.2 +2.0 −4.6 (model) ± 2.6(lumi) mb at √ s = 7 TeV. The single-and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton-antiproton and protonproton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.

... Paper 1 to 1 of 1. ALICE technical design report of the inner tracking system (ITS). By ALICE... more ... Paper 1 to 1 of 1. ALICE technical design report of the inner tracking system (ITS). By ALICE Collaboration (G. Dellacasa et al.). CERN-LHCC-99-12, Jun 1999. 373pp. Hardcopy at DESY. LaTeX(US) | LaTeX(EU ...

Physics Letters B, 1992

An experimental study of three intermediate mass fragment production in the reaction Xe+ Cu at 45... more An experimental study of three intermediate mass fragment production in the reaction Xe+ Cu at 45 MeV/u is presented. Results are compared with the predictions of a conventional statistical binary decay model starting from equilibrated sources obtained both from ...

The differential production cross section of electrons from semileptonic heavy-flavour hadron dec... more The differential production cross section of electrons from semileptonic heavy-flavour hadron decays has been measured at mid-rapidity (|y| < 0.5) in proton-proton collisions at √ s = 7 TeV with ALICE at the LHC. Data were collected in the transverse momentum range 0.5 < p t < 8 GeV/c. Predictions from a fixed order perturbative QCD calculation with next-to-leading-log resummation agree with the data within the theoretical and experimental uncertainties.

Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions... more Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass M X < 200 GeV/c 2) σ SD /σ INEL = 0.21 ± 0.03, 0.20 +0.07 −0.08 , and 0.20 +0.04 −0.07 , respectively at centre-of-mass energies √ s = 0.9, 2.76, and 7 TeV; for double diffraction (for a pseudorapidity gap η > 3) σ DD /σ INEL = 0.11 ± 0.03, 0.12 ± 0.05, and 0.12 +0.05 −0.04 , respectively at √ s = 0.9, 2.76, and 7 TeV. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: σ INEL = 62.8 +2.4 −4.0 (model) ± 1.2(lumi) mb at √ s = 2.76 TeV and 73.2 +2.0 −4.6 (model) ± 2.6(lumi) mb at √ s = 7 TeV. The single-and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton-antiproton and protonproton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.

Physics Letters B, May 10, 2012

A measurement of the multi-strange Ξ− and Ω− baryons and their antiparticles by the ALICE experim... more A measurement of the multi-strange Ξ− and Ω− baryons and their antiparticles by the ALICE experiment at the CERN Large Hadron Collider (LHC) is presented for inelastic proton–proton collisions at a centre-of-mass energy of 7 TeV. The transverse momentum (pT) distributions were studied at mid-rapidity (| y|< 0.5) in the range of 0.6 6.0 GeV/c. We also illustrate the difference between the experimental data and model by comparing the corresponding ratios of (Ω−+ Ω¯+)/(Ξ−+ Ξ¯+) as a function of transverse mass.

Physics Letters B, Apr 25, 2012

The ALICE Collaboration reports the measurement of the relative J/ψ yield as a function of charge... more The ALICE Collaboration reports the measurement of the relative J/ψ yield as a function of charged particle pseudorapidity density dNch/dη in pp collisions at s= 7 TeV at the LHC. J/ψ particles are detected for pt> 0, in the rapidity interval| y|< 0.9 via decay into e+ e−, and in the interval 2.5 0. In the highest multiplicity interval with〈 dNch/dη (bin)〉= 24.1, corresponding to four times the minimum bias multiplicity density, an enhancement relative to the minimum bias J/ψ yield by a factor of about 5 at 2.5

Physics Letters B, 2016

The production of the hypertriton nuclei 3 Λ H and 3 Λ H has been measured for the first time in ... more The production of the hypertriton nuclei 3 Λ H and 3 Λ H has been measured for the first time in Pb-Pb collisions at √ s NN = 2.76 TeV with the ALICE experiment at LHC. The p T-integrated 3 Λ H yield in one unity of rapidity, dN/dy ×B.R. (3 Λ H→ 3 He,π −) = (3.86 ± 0.77(stat.) ± 0.68(syst.)) × 10 −5 in the 0-10% most central collisions, is consistent with the predictions from a statistical thermal model using the same temperature as for the light hadrons. The coalescence parameter B 3 shows a dependence on the transverse momentum, similar to the B 2 of deuterons and the B 3 of 3 He nuclei. The ratio of yields S 3 = 3 Λ H/(3 He×Λ/p) was measured to be S 3 = 0.60 ± 0.13 (stat.) ± 0.21 (syst.) in 0-10% centrality events; this value is compared to different theoretical models. The measured S 3 is compatible with thermal model predictions. The measured 3 Λ H lifetime, τ = 181 +54 −39 (stat.) ± 33(syst.) ps is in agreement within 1σ with the world average value.

Physics Letters B, 2018

√ s NN = 5.02 TeV, respectively. Both the jet energy and the jet mass are expected to be sensitiv... more √ s NN = 5.02 TeV, respectively. Both the jet energy and the jet mass are expected to be sensitive to jet quenching in the hot Quantum Chromodynamics (QCD) matter created in nuclear collisions at collider energies. Jets are reconstructed from charged particles using the anti-k T jet algorithm and resolution parameter R = 0.4. The jets are measured in the pseudorapidity range |η jet | < 0.5 and in three intervals of transverse momentum between 60 GeV/c and 120 GeV/c. The measurement of the jet mass in central Pb-Pb collisions is compared to the jet mass as measured in p-Pb reference collisions, to vacuum event generators, and to models including jet quenching. It is observed that the jet mass in central Pb-Pb collisions is consistent within uncertainties with p-Pb reference measurements. Furthermore, the measured jet mass in Pb-Pb collisions is not reproduced by the quenching models considered in this letter and is found to be consistent with PYTHIA expectations within systematic uncertainties.

Journal of Physics: Conference Series, 2013

Heavy quarks are produced in early partonic hard scatterings and experience the full history of a... more Heavy quarks are produced in early partonic hard scatterings and experience the full history of a heavy-ion collision. Consequently heavy quarks are a good tool to study properties of the hot and dense medium. In proton-proton collisions, the study of the production of heavy quarks provides an important test for perturbative QCD and serves as a reference for heavy ion collisions. Heavy-flavour measurements in the semi-electronic channel are performed with ALICE at midrapidity. We present the measurement of the pT-differential cross section in proton-proton collisions at √ s = 7 TeV, and of the nuclear modification factor and elliptic flow in Pb-Pb collisions at √ sNN = 2.76 TeV.

The European Physical Journal C, 2013

Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions... more Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass M X < 200 GeV/c 2) σ SD /σ INEL = 0.21 ± 0.03, 0.20 +0.07 −0.08 , and 0.20 +0.04 −0.07 , respectively at centre-of-mass energies √ s = 0.9, 2.76, and 7 TeV; for double diffraction (for a pseudorapidity gap η > 3) σ DD /σ INEL = 0.11 ± 0.03, 0.12 ± 0.05, and 0.12 +0.05 −0.04 , respectively at √ s = 0.9, 2.76, and 7 TeV. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: σ INEL = 62.8 +2.4 −4.0 (model) ± 1.2(lumi) mb at √ s = 2.76 TeV and 73.2 +2.0 −4.6 (model) ± 2.6(lumi) mb at √ s = 7 TeV. The single-and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton-antiproton and protonproton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.

... Paper 1 to 1 of 1. ALICE technical design report of the inner tracking system (ITS). By ALICE... more ... Paper 1 to 1 of 1. ALICE technical design report of the inner tracking system (ITS). By ALICE Collaboration (G. Dellacasa et al.). CERN-LHCC-99-12, Jun 1999. 373pp. Hardcopy at DESY. LaTeX(US) | LaTeX(EU ...

Physics Letters B, 1992

An experimental study of three intermediate mass fragment production in the reaction Xe+ Cu at 45... more An experimental study of three intermediate mass fragment production in the reaction Xe+ Cu at 45 MeV/u is presented. Results are compared with the predictions of a conventional statistical binary decay model starting from equilibrated sources obtained both from ...

The differential production cross section of electrons from semileptonic heavy-flavour hadron dec... more The differential production cross section of electrons from semileptonic heavy-flavour hadron decays has been measured at mid-rapidity (|y| < 0.5) in proton-proton collisions at √ s = 7 TeV with ALICE at the LHC. Data were collected in the transverse momentum range 0.5 < p t < 8 GeV/c. Predictions from a fixed order perturbative QCD calculation with next-to-leading-log resummation agree with the data within the theoretical and experimental uncertainties.

Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions... more Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass M X < 200 GeV/c 2) σ SD /σ INEL = 0.21 ± 0.03, 0.20 +0.07 −0.08 , and 0.20 +0.04 −0.07 , respectively at centre-of-mass energies √ s = 0.9, 2.76, and 7 TeV; for double diffraction (for a pseudorapidity gap η > 3) σ DD /σ INEL = 0.11 ± 0.03, 0.12 ± 0.05, and 0.12 +0.05 −0.04 , respectively at √ s = 0.9, 2.76, and 7 TeV. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: σ INEL = 62.8 +2.4 −4.0 (model) ± 1.2(lumi) mb at √ s = 2.76 TeV and 73.2 +2.0 −4.6 (model) ± 2.6(lumi) mb at √ s = 7 TeV. The single-and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton-antiproton and protonproton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.

Physics Letters B, May 10, 2012

A measurement of the multi-strange Ξ− and Ω− baryons and their antiparticles by the ALICE experim... more A measurement of the multi-strange Ξ− and Ω− baryons and their antiparticles by the ALICE experiment at the CERN Large Hadron Collider (LHC) is presented for inelastic proton–proton collisions at a centre-of-mass energy of 7 TeV. The transverse momentum (pT) distributions were studied at mid-rapidity (| y|< 0.5) in the range of 0.6 6.0 GeV/c. We also illustrate the difference between the experimental data and model by comparing the corresponding ratios of (Ω−+ Ω¯+)/(Ξ−+ Ξ¯+) as a function of transverse mass.

Physics Letters B, Apr 25, 2012

The ALICE Collaboration reports the measurement of the relative J/ψ yield as a function of charge... more The ALICE Collaboration reports the measurement of the relative J/ψ yield as a function of charged particle pseudorapidity density dNch/dη in pp collisions at s= 7 TeV at the LHC. J/ψ particles are detected for pt> 0, in the rapidity interval| y|< 0.9 via decay into e+ e−, and in the interval 2.5 0. In the highest multiplicity interval with〈 dNch/dη (bin)〉= 24.1, corresponding to four times the minimum bias multiplicity density, an enhancement relative to the minimum bias J/ψ yield by a factor of about 5 at 2.5