The centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb c... more The centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at √ s NN = 2.76 TeV is presented. The charged-particle density normalized per participating nucleon pair increases by about a factor of two from peripheral (70-80%) to central (0-5%) collisions. The centrality dependence is found to be similar to that observed at lower collision energies. The data are compared with models based on different mechanisms for particle production in nuclear collisions.
The production of K * (892) 0 and φ (1020) in pp collisions at √ s=7 TeV was measured by the ALIC... more The production of K * (892) 0 and φ (1020) in pp collisions at √ s=7 TeV was measured by the ALICE experiment at the LHC. The yields and the transverse momentum spectra d 2 N/dydp T at midrapidity |y|< 0.5 in the range 0<p T <6 GeV/c for K * (892) 0 and 0.4<p T <6 GeV/c for φ (1020) are reported and compared to model predictions. Using the yield of pions, kaons, and Ω baryons measured previously by ALICE at √ s=7 TeV, the ratios K ratios are similar to those found at lower centre-of-mass energies. In contrast, the φ /π − ratio, which has been observed to increase with energy, seems to saturate above 200 GeV. The (Ω + Ω)/φ ratio in the p T range 1-5 GeV/c is found to be in good agreement with the prediction of the HIJING/BB v2.0 model with a strong colour field.
The p T -differential inclusive production cross section of the prompt charm-strange meson D + s ... more The p T -differential inclusive production cross section of the prompt charm-strange meson D + s in the rapidity range |y| < 0.5 was measured in proton-proton collisions at √ s = 7 TeV at the LHC using the ALICE detector. The analysis was performed on a data sample of 2.98×10 8 events collected with a minimum-bias trigger. The corresponding integrated luminosity is L int = 4.8 nb −1 . Reconstructing the decay D + s → φ π + , with φ → K − K + , and its charge conjugate, about 480 D ± s mesons were counted, after selection cuts, in the transverse momentum range 2 < p T < 12 GeV/c. The results are compared with the prediction of a model based on perturbative QCD. The ratios of the cross sections of four D meson species (namely D 0 , D + , D * + and D + s ) were determined both as a function of p T and integrated over p T after extrapolating to full p T range, together with the strangeness suppression factor in charm fragmentation. The obtained values are found to be compatible within uncertainties with those measured by other experiments in e + e − , ep and pp interactions at various centre-of-mass energies.
The first measurement of neutron emission in electromagnetic dissociation of 208 Pb nuclei at the... more The first measurement of neutron emission in electromagnetic dissociation of 208 Pb nuclei at the LHC is presented. The measurement is performed using the neutron Zero Degree Calorimeters of the ALICE experiment, which detect neutral particles close to beam rapidity. The measured cross sections of single and mutual electromagnetic dissociation of Pb nuclei at √ s NN = 2.76 TeV with neutron emission are σ single EMD = 187.2 ± 0.2 (stat.) +13.8 −12.0 (syst.) b and σ mutual EMD = 6.2 ± 0.1 (stat.) ±0.4 (syst.) b respectively. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model.
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. Electrons from heavy-flavour decays in pp collisions at √ s = 7 TeV 1 Electrons from heavy-flavour decays in pp collisions at √ s = 7 TeV 25 the Ministry of Science and Technology of China (MSTC);
Purpose: Sensory peripheral neuropathy is a common and sometimes debilitating toxicity associated... more Purpose: Sensory peripheral neuropathy is a common and sometimes debilitating toxicity associated with paclitaxel therapy. This study aims to identify genetic risk factors for the development of this toxicity.
Measurements of the sphericity of primary charged particles in minimum bias proton-proton collisi... more Measurements of the sphericity of primary charged particles in minimum bias proton-proton collisions at √ s = 0.9, 2.76 and 7 TeV with the ALICE detector at the LHC are presented. The observable is linearized to be collinear safe and is measured in the plane perpendicular to the beam direction using primary charged tracks with p T ≥ 0.5 GeV/c in |η| ≤ 0.8. The mean sphericity as a function of the charged particle multiplicity at mid-rapidity (N ch ) is reported for events with different p T scales ("soft" and "hard") defined by the transverse momentum of the leading particle. In addition, the mean charged particle transverse momentum versus multiplicity is presented for the different event classes, and the sphericity distributions in bins of multiplicity are presented. The data are compared with calculations of standard Monte Carlo event generators. The transverse sphericity is found to grow with multiplicity at all collision energies, with a steeper rise at low N ch , whereas the event generators show the opposite tendency. The combined study of the sphericity and the mean p T with multiplicity indicates that most of the tested event generators produce events with higher multiplicity by generating more back-to-back jets resulting in decreased sphericity (and isotropy). The PYTHIA6 generator with tune PERUGIA-2011 exhibits a noticeable improvement in describing the data, compared to the other tested generators.
The production of the prompt charm mesons D 0 , D + , D * + , and their antiparticles, was measur... more The production of the prompt charm mesons D 0 , D + , D * + , and their antiparticles, was measured with the ALICE detector in Pb-Pb collisions at the LHC, at a centre-of-mass energy √ s NN = 2.76 TeV per nucleon-nucleon collision. The p t -differential production yields in the range 2 < p t < 16 GeV/c at central rapidity, |y| < 0.5, were used to calculate the nuclear modification factor R AA with respect to a proton-proton reference obtained from the cross section measured at √ s = 7 TeV and scaled to √ s = 2.76 TeV. For the three meson species, R AA shows a suppression by a factor 3-4, for transverse momenta larger than 5 GeV/c in the 20% most central collisions. The suppression is reduced for peripheral collisions. * See Appendix A for the list of collaboration members Suppression of high p t D mesons in Pb-Pb collisions at √ s NN = 2.76 TeV 3 Suppression of high p t D mesons in Pb-Pb collisions at √ s NN = 2.76 TeV Suppression of high p t D mesons in Pb-Pb collisions at √ s NN = 2.76 TeV 7 central collisions), aimed at reducing the large combinatorial background.
We report on the high statistics two-pion correlation functions from pp collisions at √ s = 0.9 T... more We report on the high statistics two-pion correlation functions from pp collisions at √ s = 0.9 TeV and √ s = 7 TeV, measured by the ALICE experiment at the Large Hadron Collider. The correlation functions as well as the extracted source radii scale with event multiplicity and pair momentum. When analyzed in the same multiplicity and pair transverse momentum range, the correlation is similar at the two collision energies. A threedimensional femtoscopic analysis shows an increase of the emission zone with increasing event multiplicity as well as decreasing homogeneity lengths with increasing transverse momentum. The latter trend gets more pronounced as multiplicity increases. This suggests the development of space-momentum correlations, at least for collisions producing a high multiplicity of particles. We consider these trends in the context of previous femtoscopic studies in high-energy hadron and heavy-ion collisions, and discuss possible underlying physics mechanisms. Detailed analysis of the correlation reveals an exponential shape in the outward and longitudinal directions, while the sideward remains a Gaussian. This is interpreted as a result of a significant contribution of strongly decaying resonances to the emission region shape. Significant non-femtoscopic correlations are observed, and are argued to be the consequence of "mini-jet"-like structures extending to low p T . They are well reproduced by the Monte-Carlo generators and seen also in π + π − correlations. 25.75.Gz, 25.70.Pq
A measurement of the multi-strange Ξ − and Ω − baryons and their antiparticles by the ALICE exper... 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 proton-proton collisions at centre of mass energy of 7 TeV. The transverse momentum (p t ) distributions were studied at mid-rapidity (|y| < 0.5) in the range of 0.6 < p t < 8.5 GeV/c for Ξ − and Ξ + baryons, and in the range of 0.8 < p t < 5 GeV/c for Ω − and Ω + . Baryons and anti-baryons were measured as separate particles and we find that the baryon to antibaryon ratio of both particle species is consistent with unity over the entire range of the measurement. The statistical precision of the current LHC data has allowed us to measure a difference between the mean p t of Ξ − (Ξ + ) and Ω − (Ω + ). Particle yields, mean p t , and the spectra in the intermediate p t range are not well described by the PYTHIA Perugia 2011 tune Monte Carlo event generator, which has been tuned to reproduce the early LHC data. The discrepancy is largest for Ω − (Ω + ). This PYTHIA tune approaches the p t spectra of Ξ − and Ξ + baryons below p t < 0.85 GeV/c and describes the Ξ − and Ξ + spectra above p t > 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.
The centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb c... more The centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at √ s NN = 2.76 TeV is presented. The charged-particle density normalized per participating nucleon pair increases by about a factor of two from peripheral (70-80%) to central (0-5%) collisions. The centrality dependence is found to be similar to that observed at lower collision energies. The data are compared with models based on different mechanisms for particle production in nuclear collisions.
The production of K * (892) 0 and φ (1020) in pp collisions at √ s=7 TeV was measured by the ALIC... more The production of K * (892) 0 and φ (1020) in pp collisions at √ s=7 TeV was measured by the ALICE experiment at the LHC. The yields and the transverse momentum spectra d 2 N/dydp T at midrapidity |y|< 0.5 in the range 0<p T <6 GeV/c for K * (892) 0 and 0.4<p T <6 GeV/c for φ (1020) are reported and compared to model predictions. Using the yield of pions, kaons, and Ω baryons measured previously by ALICE at √ s=7 TeV, the ratios K ratios are similar to those found at lower centre-of-mass energies. In contrast, the φ /π − ratio, which has been observed to increase with energy, seems to saturate above 200 GeV. The (Ω + Ω)/φ ratio in the p T range 1-5 GeV/c is found to be in good agreement with the prediction of the HIJING/BB v2.0 model with a strong colour field.
The p T -differential inclusive production cross section of the prompt charm-strange meson D + s ... more The p T -differential inclusive production cross section of the prompt charm-strange meson D + s in the rapidity range |y| < 0.5 was measured in proton-proton collisions at √ s = 7 TeV at the LHC using the ALICE detector. The analysis was performed on a data sample of 2.98×10 8 events collected with a minimum-bias trigger. The corresponding integrated luminosity is L int = 4.8 nb −1 . Reconstructing the decay D + s → φ π + , with φ → K − K + , and its charge conjugate, about 480 D ± s mesons were counted, after selection cuts, in the transverse momentum range 2 < p T < 12 GeV/c. The results are compared with the prediction of a model based on perturbative QCD. The ratios of the cross sections of four D meson species (namely D 0 , D + , D * + and D + s ) were determined both as a function of p T and integrated over p T after extrapolating to full p T range, together with the strangeness suppression factor in charm fragmentation. The obtained values are found to be compatible within uncertainties with those measured by other experiments in e + e − , ep and pp interactions at various centre-of-mass energies.
The first measurement of neutron emission in electromagnetic dissociation of 208 Pb nuclei at the... more The first measurement of neutron emission in electromagnetic dissociation of 208 Pb nuclei at the LHC is presented. The measurement is performed using the neutron Zero Degree Calorimeters of the ALICE experiment, which detect neutral particles close to beam rapidity. The measured cross sections of single and mutual electromagnetic dissociation of Pb nuclei at √ s NN = 2.76 TeV with neutron emission are σ single EMD = 187.2 ± 0.2 (stat.) +13.8 −12.0 (syst.) b and σ mutual EMD = 6.2 ± 0.1 (stat.) ±0.4 (syst.) b respectively. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model.
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. Electrons from heavy-flavour decays in pp collisions at √ s = 7 TeV 1 Electrons from heavy-flavour decays in pp collisions at √ s = 7 TeV 25 the Ministry of Science and Technology of China (MSTC);
Purpose: Sensory peripheral neuropathy is a common and sometimes debilitating toxicity associated... more Purpose: Sensory peripheral neuropathy is a common and sometimes debilitating toxicity associated with paclitaxel therapy. This study aims to identify genetic risk factors for the development of this toxicity.
Measurements of the sphericity of primary charged particles in minimum bias proton-proton collisi... more Measurements of the sphericity of primary charged particles in minimum bias proton-proton collisions at √ s = 0.9, 2.76 and 7 TeV with the ALICE detector at the LHC are presented. The observable is linearized to be collinear safe and is measured in the plane perpendicular to the beam direction using primary charged tracks with p T ≥ 0.5 GeV/c in |η| ≤ 0.8. The mean sphericity as a function of the charged particle multiplicity at mid-rapidity (N ch ) is reported for events with different p T scales ("soft" and "hard") defined by the transverse momentum of the leading particle. In addition, the mean charged particle transverse momentum versus multiplicity is presented for the different event classes, and the sphericity distributions in bins of multiplicity are presented. The data are compared with calculations of standard Monte Carlo event generators. The transverse sphericity is found to grow with multiplicity at all collision energies, with a steeper rise at low N ch , whereas the event generators show the opposite tendency. The combined study of the sphericity and the mean p T with multiplicity indicates that most of the tested event generators produce events with higher multiplicity by generating more back-to-back jets resulting in decreased sphericity (and isotropy). The PYTHIA6 generator with tune PERUGIA-2011 exhibits a noticeable improvement in describing the data, compared to the other tested generators.
The production of the prompt charm mesons D 0 , D + , D * + , and their antiparticles, was measur... more The production of the prompt charm mesons D 0 , D + , D * + , and their antiparticles, was measured with the ALICE detector in Pb-Pb collisions at the LHC, at a centre-of-mass energy √ s NN = 2.76 TeV per nucleon-nucleon collision. The p t -differential production yields in the range 2 < p t < 16 GeV/c at central rapidity, |y| < 0.5, were used to calculate the nuclear modification factor R AA with respect to a proton-proton reference obtained from the cross section measured at √ s = 7 TeV and scaled to √ s = 2.76 TeV. For the three meson species, R AA shows a suppression by a factor 3-4, for transverse momenta larger than 5 GeV/c in the 20% most central collisions. The suppression is reduced for peripheral collisions. * See Appendix A for the list of collaboration members Suppression of high p t D mesons in Pb-Pb collisions at √ s NN = 2.76 TeV 3 Suppression of high p t D mesons in Pb-Pb collisions at √ s NN = 2.76 TeV Suppression of high p t D mesons in Pb-Pb collisions at √ s NN = 2.76 TeV 7 central collisions), aimed at reducing the large combinatorial background.
We report on the high statistics two-pion correlation functions from pp collisions at √ s = 0.9 T... more We report on the high statistics two-pion correlation functions from pp collisions at √ s = 0.9 TeV and √ s = 7 TeV, measured by the ALICE experiment at the Large Hadron Collider. The correlation functions as well as the extracted source radii scale with event multiplicity and pair momentum. When analyzed in the same multiplicity and pair transverse momentum range, the correlation is similar at the two collision energies. A threedimensional femtoscopic analysis shows an increase of the emission zone with increasing event multiplicity as well as decreasing homogeneity lengths with increasing transverse momentum. The latter trend gets more pronounced as multiplicity increases. This suggests the development of space-momentum correlations, at least for collisions producing a high multiplicity of particles. We consider these trends in the context of previous femtoscopic studies in high-energy hadron and heavy-ion collisions, and discuss possible underlying physics mechanisms. Detailed analysis of the correlation reveals an exponential shape in the outward and longitudinal directions, while the sideward remains a Gaussian. This is interpreted as a result of a significant contribution of strongly decaying resonances to the emission region shape. Significant non-femtoscopic correlations are observed, and are argued to be the consequence of "mini-jet"-like structures extending to low p T . They are well reproduced by the Monte-Carlo generators and seen also in π + π − correlations. 25.75.Gz, 25.70.Pq
A measurement of the multi-strange Ξ − and Ω − baryons and their antiparticles by the ALICE exper... 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 proton-proton collisions at centre of mass energy of 7 TeV. The transverse momentum (p t ) distributions were studied at mid-rapidity (|y| < 0.5) in the range of 0.6 < p t < 8.5 GeV/c for Ξ − and Ξ + baryons, and in the range of 0.8 < p t < 5 GeV/c for Ω − and Ω + . Baryons and anti-baryons were measured as separate particles and we find that the baryon to antibaryon ratio of both particle species is consistent with unity over the entire range of the measurement. The statistical precision of the current LHC data has allowed us to measure a difference between the mean p t of Ξ − (Ξ + ) and Ω − (Ω + ). Particle yields, mean p t , and the spectra in the intermediate p t range are not well described by the PYTHIA Perugia 2011 tune Monte Carlo event generator, which has been tuned to reproduce the early LHC data. The discrepancy is largest for Ω − (Ω + ). This PYTHIA tune approaches the p t spectra of Ξ − and Ξ + baryons below p t < 0.85 GeV/c and describes the Ξ − and Ξ + spectra above p t > 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.
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