Refine
Year of publication
Document Type
- Preprint (569)
- Article (363)
- Conference Proceeding (1)
Language
- English (933)
Has Fulltext
- yes (933)
Is part of the Bibliography
- no (933)
Keywords
- Heavy Ion Experiments (18)
- Hadron-Hadron scattering (experiments) (11)
- BESIII (6)
- Heavy-ion collision (6)
- LHC (5)
- Hadron-Hadron Scattering (4)
- Quark-Gluon Plasma (4)
- ALICE experiment (3)
- Branching fractions (3)
- Hadronic decays (3)
- Heavy Ions (3)
- Jets and Jet Substructure (3)
- Accelerators & Beams (2)
- Atomic, Molecular & Optical (2)
- Beauty production (2)
- Charm physics (2)
- Charmonium (2)
- Clinical genetics (2)
- Cross section (2)
- Experimental nuclear physics (2)
- Experimental particle physics (2)
- Jets (2)
- Lepton-Nucleon Scattering (experiments) (2)
- Particle and resonance production (2)
- Particle correlations and fluctuations (2)
- Pb–Pb collisions (2)
- Psychiatric disorders (2)
- Single electrons (2)
- pp collisions (2)
- ALICE (1)
- ALICE detector (1)
- Accelerators & storage rings (1)
- Agoraphobia (1)
- Angular distribution (1)
- Annihilation (1)
- Anti-nuclei (1)
- Atomic & molecular beams (1)
- Beam loss (1)
- Bhabha (1)
- Branching fraction (1)
- Centrality Class (1)
- Centrality Selection (1)
- Charge-transfer collisions (1)
- Circular accelerators (1)
- Clinical Trials and Observations (1)
- Collective Flow (1)
- Cross section measurements (1)
- D meson (1)
- D0 and D+ mesons (1)
- Dalitz decay (1)
- D⁰ meson (1)
- Electromagnetic form factor (1)
- Electron-pion identification (1)
- Electronic transitions (1)
- Electroweak interaction (1)
- Elliptic flow (1)
- Fibre/foam sandwich radiator (1)
- Hadron-Hadron Scattering Heavy (1)
- Hadron-hadron interactions (1)
- Hadronic cross section (1)
- Hadrons (1)
- Heavy Ion Experiment (1)
- Heavy Quark Production (1)
- Heavy flavor production (1)
- Heavy ions (1)
- Heavy-flavour decay muons (1)
- Heavy-flavour production (1)
- Human behaviour (1)
- Imaging genetics (1)
- Initial state radiation (1)
- Invariant Mass Distribution (1)
- Ionisation energy loss (1)
- Learning and memory (1)
- Low & intermediate-energy accelerators (1)
- Lymphoid Neoplasia (1)
- Mid-rapidity (1)
- Minimum Bias (1)
- Molecular neuroscience (1)
- Monte Carlo (1)
- Multi-strange baryons (1)
- Multi-wire proportional drift chamber (1)
- Muon anomaly (1)
- NPSR1 (1)
- Neural network (1)
- Panic disorder (1)
- Particle Correlations and Fluctuations (1)
- Personalized medicine (1)
- Photon counting (1)
- Pion form factor (1)
- Polarization (1)
- Predictive markers (1)
- Production Cross Section (1)
- Properties of Hadrons (1)
- Proton–proton (1)
- QCD (1)
- Quark Gluon Plasma (1)
- Quark Production (1)
- Quark gluon plasma (1)
- R value (1)
- Radiation detectors (1)
- Rapidity Range (1)
- Relativistic heavy ion physics (1)
- Relativistic heavy-ion collisions (1)
- Resolution Parameter (1)
- Systematic Uncertainty (1)
- TR (1)
- Time Projection Chamber (1)
- Tracking (1)
- Transition radiation detector (1)
- Trigger (1)
- Triple quarkonia (1)
- Vector Boson Production (1)
- Westphal-Paradigm (1)
- Xenon-based gas mixture (1)
- Y (4260) (1)
- amino acid PET (1)
- antibodies (1)
- artificial intelligence (1)
- b-cell lymphomas (1)
- bendamustine (1)
- chemotherapy regimen (1)
- chimeric antigen receptor t-cell therapy (1)
- chimeric antigen receptors (1)
- dE/dx (1)
- diphoton (1)
- e+e− annihilation (1)
- excitation transport (1)
- fMRI (1)
- glioma (1)
- heavy ion experiments (1)
- hematopoietic stem cell transplantation (1)
- leukapheresis (1)
- light harvesting networks (1)
- light–energy conversion (1)
- luminosity (1)
- lymphoma (1)
- open quantum systems (1)
- quantum transport (1)
- quark gluon plasma (1)
- rituximab (1)
- semiconductors (1)
- spectra (1)
- treatment-related changes (1)
- tumor progression (1)
- x-ray techniques (1)
- Σ hyperon (1)
Institute
At particle collider experiments, elementary particle interactions with large momentum transfer produce quarks and gluons (known as partons) whose evolution is governed by the strong force, as described by the theory of quantum chromodynamics (QCD). The vacuum is not transparent to the partons and induces gluon radiation and quark pair production in a process that can be described as a parton shower. Studying the pattern of the parton shower is one of the key experimental tools in understanding the properties of QCD. This pattern is expected to depend on the mass of the initiating parton, through a phenomenon known as the dead-cone effect, which predicts a suppression of the gluon spectrum emitted by a heavy quark of mass m and energy E, within a cone of angular size m/E around the emitter. A direct observation of the dead-cone effect in QCD has not been possible until now, due to the challenge of reconstructing the cascading quarks and gluons from the experimentally accessible bound hadronic states. We report the first direct observation of the QCD dead-cone by using new iterative declustering techniques to reconstruct the parton shower of charm quarks. This result confirms a fundamental feature of QCD, which is derived more generally from its origin as a gauge quantum field theory. Furthermore, the measurement of a dead-cone angle constitutes a direct experimental observation of the non-zero mass of the charm quark, which is a fundamental constant in the standard model of particle physics.
In particle collider experiments, elementary particle interactions with large momentum transfer produce quarks and gluons (known as partons) whose evolution is governed by the strong force, as described by the theory of quantum chromodynamics (QCD). These partons subsequently emit further partons in a process that can be described as a parton shower which culminates in the formation of detectable hadrons. Studying the pattern of the parton shower is one of the key experimental tools for testing QCD. This pattern is expected to depend on the mass of the initiating parton, through a phenomenon known as the dead-cone effect, which predicts a suppression of the gluon spectrum emitted by a heavy quark of mass mQ and energy E, within a cone of angular size mQ/E around the emitter. Previously, a direct observation of the dead-cone effect in QCD had not been possible, owing to the challenge of reconstructing the cascading quarks and gluons from the experimentally accessible hadrons. We report the direct observation of the QCD dead cone by using new iterative declustering techniques to reconstruct the parton shower of charm quarks. This result confirms a fundamental feature of QCD. Furthermore, the measurement of a dead-cone angle constitutes a direct experimental observation of the non-zero mass of the charm quark, which is a fundamental constant in the standard model of particle physics.
The production of prompt Λc+ baryons at midrapidity (|y|<0.5) was measured in central (0–10%) and mid-central (30–50%) Pb–Pb collisions at the center-of-mass energy per nucleon–nucleon pair √sNN=5.02 TeV with the ALICE detector. The results are more precise, more differential in centrality, and reach much lower transverse momentum (pT=1 GeV/c) with respect to previous measurements performed by the ALICE, STAR, and CMS Collaborations in nucleus–nucleus collisions, allowing for an extrapolation down to pT=0. The pT-differential Λc+/D0 ratio is enhanced with respect to the pp measurement for 4<pT<8 GeV/c by 3.7 standard deviations (σ), while the pT-integrated ratios are compatible within 1σ. The observed trend is similar to that observed in the strange sector for the Λ/KS0 ratio. Model calculations including coalescence or statistical hadronization for charm-hadron formation are compared with the data.
In quantum scattering processes between two particles, aspects characterizing the strong and Coulomb forces can be observed in kinematic distributions of the particle pairs. The sensitivity to the interaction potential reaches a maximum at low relative momentum and vanishing distance between the two particles. Ultrarelativistic heavy-ion collisions at the LHC provide an abundant source of many hadron species and can be employed as a measurement method of scattering parameters that is complementary to scattering experiments. This study confirms that momentum correlations of particles produced in Pb–Pb collisions at the LHC provide an accurate measurement of kaon–proton scattering parameters at low relative momentum, allowing precise access to the K−p→K−p process. This work also validates the femtoscopic measurement in ultrarelativistic heavy-ion collisions as an alternative to scattering experiments and a complementary tool to the study of exotic atoms with comparable precision. In this work, the first femtoscopic measurement of momentum correlations of K−p(K+p‾) and K+p(K−p‾) pairs in Pb–Pb collisions at centre-of-mass energy per nucleon pair of sNN=5.02 TeV registered by the ALICE experiment is reported. The components of the K−p complex scattering length are extracted and found to be ℜf0=−0.91±0.03(stat)−0.03+0.17(syst) and ℑf0=0.92±0.05(stat)−0.33+0.12(syst). The results are compared with chiral effective field theory predictions as well as with existing data from dedicated scattering and exotic kaonic atom experiments.
The measurement of the production of f0(980) in inelastic pp collisions at √s=5.02 TeV is presented. This is the first reported measurement of inclusive f0(980) yield at LHC energies. The production is measured at midrapidity, |y|<0.5, in a wide transverse momentum range, 0<pT<16 GeV/c, by reconstructing the resonance in the f0(980) →π+π− hadronic decay channel using the ALICE detector. The pT-differential yields are compared to those of pions, protons and ϕ mesons as well as to predictions from the HERWIG 7.2 QCD-inspired Monte Carlo event generator and calculations from a coalescence model that uses the AMPT model as an input. The ratio of the pT-integrated yield of f0(980) relative to pions is compared to measurements in e+e− and pp collisions at lower energies and predictions from statistical hadronisation models and HERWIG 7.2. A mild collision energy dependence of the f0(980) to pion production is observed in pp collisions from SPS to LHC energies. All considered models underpredict the pT-integrated 2f0(980)/(π+ +π−) ratio. The prediction from the canonical statistical hadronisation model assuming a zero total strangeness content of f0(980) is consistent with the data within 1.9σ and is the closest to the data. The results provide an essential reference for future measurements of the particle yield and nuclear modification in p–Pb and Pb–Pb collisions, which have been proposed to be instrumental to probe the elusive nature and quark composition of the f0(980) scalar meson.
The production of prompt D0, Ds+, and Λc+ hadrons, and their ratios, Ds+/D0 and Λc+/D0, are measured in proton–proton collisions at √s=13 TeV at midrapidity (|y|<0.5) with the ALICE detector at the LHC. The measurements are performed as a function of the charm-hadron transverse momentum (pT) in intervals of charged-particle multiplicity, measured with two multiplicity estimators covering different pseudorapidity regions. While the strange to non-strange Ds+/D0 ratio indicates no significant multiplicity dependence, the baryon-to-meson pT-differential Λc+/D0 ratio shows a multiplicity-dependent enhancement, with a significance of 5.3σ for 1<pT<12 GeV/c, comparing the highest multiplicity interval with respect to the lowest one. The measurements are compared with a theoretical model that explains the multiplicity dependence by a canonical treatment of quantum charges in the statistical hadronisation approach, and with predictions from event generators that implement colour reconnection mechanisms beyond the leading colour approximation to model the hadronisation process. The Λc+/D0 ratios as a function of pT present a similar shape and magnitude as the Λ/KS0 ratios in comparable multiplicity intervals, suggesting a potential common mechanism for light- and charm-hadron formation, with analogous multiplicity dependence. The pT-integrated ratios, extrapolated down to pT=0, do not show a significant dependence on multiplicity within the uncertainties.
Fluctuation measurements are important sources of information on the mechanism of particle production at LHC energies. This article reports the first experimental results on third-order cumulants of the net-proton distributions in Pb–Pb collisions at a center-of-mass energy √sNN=5.02 TeV recorded by the ALICE detector. The results on the second-order cumulants of net-proton distributions at √sNN=2.76 and 5.02 TeV are also discussed in view of effects due to the global and local baryon number conservation. The results demonstrate the presence of long-range rapidity correlations between protons and antiprotons. Such correlations originate from the early phase of the collision. The experimental results are compared with HIJING and EPOS model calculations, and the dependence of the fluctuation measurements on the phase-space coverage is examined in the context of lattice quantum chromodynamics (LQCD) and hadron resonance gas (HRG) model estimations. The measured third-order cumulants are consistent with zero within experimental uncertainties of about 4% and are described well by LQCD and HRG predictions.
We present the first systematic comparison of the charged-particle pseudorapidity densities for three widely different collision systems, pp, pPb, and PbPb, at the top energy of the Large Hadron Collider (√sNN=5.02TeV) measured over a wide pseudorapidity range (−3.5<η<5), the widest possible among the four experiments at that facility. The systematic uncertainties are minimised since the measurements are recorded by the same experimental apparatus (ALICE). The distributions for pPb and PbPb collisions are determined as a function of the centrality of the collisions, while results from pp collisions are reported for inelastic events with at least one charged particle at midrapidity. The charged-particle pseudorapidity densities are, under simple and robust assumptions, transformed to charged-particle rapidity densities. This allows for the calculation and the presentation of the evolution of the width of the rapidity distributions and of a lower bound on the Bjorken energy density, as a function of the number of participants in all three collision systems. We find a decreasing width of the particle production, and roughly a smooth ten fold increase in the energy density, as the system size grows, which is consistent with a gradually higher dense phase of matter.
Production of inclusive charmonia in pp collisions at center-of-mass energy of √s = 13 TeV and p–Pb collisions at center-of-mass energy per nucleon pair of √sNN = 8.16 TeV is studied as a function of charged-particle pseudorapidity density with ALICE. Ground and excited charmonium states (J/ψ, ψ(2S)) are measured from their dimuon decays in the interval of rapidity in the center-of-mass frame 2.5 < ycms < 4.0 for pp collisions, and 2.03 < ycms < 3.53 and −4.46 < ycms < −2.96 for p–Pb collisions. The charged-particle pseudorapidity density is measured around midrapidity (|η| < 1.0). In pp collisions, the measured charged-particle multiplicity extends to about six times the average value, while in p-Pb collisions at forward (backward) rapidity a multiplicity corresponding to about three (four) times the average is reached. The ψ(2S) yield increases with the charged-particle pseudorapidity density. The ratio of ψ(2S) over J/ψ yield does not show a significant multiplicity dependence in either colliding system, suggesting a similar behavior of J/ψ and ψ(2S) yields with respect to charged-particle pseudorapidity density. Results for the ψ(2S) yield and its ratio with respect to J/ψ agree with available model calculations.
Correlations between moments of different flow coefficients are measured in Pb–Pb collisions at √sNN=5.02TeV recorded with the ALICE detector. These new measurements are based on multiparticle mixed harmonic cumulants calculated using charged particles in the pseudorapidity region |η| <0.8with the transverse momentum range 0.2 <pT<5.0GeV/c. The centrality dependence of correlations between two flow coefficients as well as the correlations between three flow coefficients, both in terms of their second moments, are shown. In addition, a collection of mixed harmonic cumulants involving higher moments of v2and v3is measured for the first time, where the characteristic signature of negative, positive and negative signs of four-, six-and eight-particle cumulants are observed, respectively. The measurements are compared to the hydrodynamic calculations using iEBE-VISHNU with AMPT and TRENTo initial conditions. It is shown that the measurements carried out using the LHC Run 2 data in 2015 have the precision to explore the details of initial-state fluctuations and probe the nonlinear hydrodynamic response of v2and v3to their corresponding initial anisotropy coefficients ε2and ε3. These new studies on correlations between three flow coefficients as well as correlations between higher moments of two different flow coefficients will pave the way to tighten constraints on initial-state models and help to extract precise information on the dynamic evolution of the hot and dense matter created in heavy-ion collisions at the LHC.