Refine
Year of publication
Document Type
- Preprint (780)
- Article (488)
- Book (3)
- Working Paper (2)
- Conference Proceeding (1)
Has Fulltext
- yes (1274)
Is part of the Bibliography
- no (1274)
Keywords
- Heavy Ion Experiments (21)
- Hadron-Hadron Scattering (14)
- Hadron-Hadron scattering (experiments) (12)
- LHC (10)
- Heavy-ion collision (6)
- Jets (6)
- ALICE experiment (4)
- Collective Flow (4)
- Heavy Ions (4)
- Heavy Quark Production (4)
- Quark-Gluon Plasma (4)
- ALICE (3)
- Jets and Jet Substructure (3)
- Quarkonium (3)
- pp collisions (3)
- Beauty production (2)
- Charm physics (2)
- Diffraction (2)
- Elastic scattering (2)
- Experimental nuclear physics (2)
- Experimental particle physics (2)
- Heavy-ion collisions (2)
- Lepton-Nucleon Scattering (experiments) (2)
- Particle Correlations and Fluctuations (2)
- Particle and resonance production (2)
- Particle correlations and fluctuations (2)
- Pb–Pb collisions (2)
- Polarization (2)
- QCD (2)
- Quark Gluon Plasma (2)
- RHIC (2)
- Relativistic heavy-ion collisions (2)
- Single electrons (2)
- 900 GeV (1)
- ALICE detector (1)
- Active middle ear implants (1)
- Acuris (1)
- Analysis and statistical methods (1)
- Anti-nuclei (1)
- Auditory system (1)
- Bacterial leakage (1)
- Biochemistry (1)
- Biophysics (1)
- Bipolar disorder (1)
- Bone conduction devices (1)
- Boosted Jets (1)
- CAD/CAM crown (1)
- Calorimeters (1)
- Canonical suppression (1)
- Cell biology (1)
- Cement gap (1)
- Centrality Class (1)
- Centrality Selection (1)
- Ceramides (1)
- Charge fluctuations (1)
- Charged-particle density (1)
- Charged-particle multiplicity (1)
- Charmonia (1)
- Circadian (1)
- Cold nuclear matter effects (1)
- Collective Flow, (1)
- Collectivity (1)
- Comparison with QCD (1)
- Conometric connection (1)
- Consensus statement (1)
- Correlation (1)
- Data processing methods (1)
- Di-hadron correlations (1)
- Electron-pion identification (1)
- Electroweak interaction (1)
- Elliptic flow (1)
- Femtoscopy (1)
- Fibre/foam sandwich radiator (1)
- Flow (1)
- Forward physics (1)
- GTP cyclohydrolase (1)
- Geldpolitik (1)
- Groomed jet radius (1)
- HBT (1)
- Hadron production (1)
- Hadron-Hadron Scattering Heavy (1)
- Hadron-hadron interactions (1)
- Hard Scattering (1)
- Health policy (1)
- Heavy Ion Experiment (1)
- Heavy flavor production (1)
- Heavy flavour production (1)
- Heavy ions (1)
- Heavy-Ion Collision (1)
- Heavy-flavour decay muons (1)
- Heavy-flavour production (1)
- Heavy-ion (1)
- Heavy-ion detectors (1)
- Homeoviscous adaptation (1)
- Inclusive spectra (1)
- Intensity interferometry (1)
- Interference fragmentation function (1)
- Invariant Mass Distribution (1)
- Ionisation energy loss (1)
- J/ψ suppression (1)
- Jet Physics (1)
- Jet Substructure (1)
- Jet substructure (1)
- Large detector systems for particle and astroparticle physics (1)
- Lipid packing (1)
- Makroökonomie (1)
- Makroökonomisches Modell (1)
- Marginal integrity (1)
- Material budget (1)
- Membrane (1)
- Membrane and lipid biology (1)
- Membrane fluidity (1)
- Membrane homeostasis (1)
- Microgap (1)
- Mid-rapidity (1)
- Minimum Bias (1)
- Mixed hearing loss (1)
- Molecular chaperones (1)
- Monte Carlo (1)
- Multi-Parton Interactions (1)
- Multi-stakeholder approach (1)
- Multi-strange baryons (1)
- Multi-wire proportional drift chamber (1)
- Multiple parton interactions (1)
- Neural network (1)
- Neutralität des Geldes (1)
- Nitric oxide (1)
- Nonflow (1)
- Nuclear modification factor (1)
- Omega lipids (1)
- Organelle (1)
- PYTHIA (1)
- Particle and Resonance Production (1)
- Particle production (1)
- Pb–Pb (1)
- Performance of High Energy Physics Detectors (1)
- Preisstarrheit (1)
- Production Cross Section (1)
- Properties of Hadrons (1)
- Protein homeostasis (1)
- Proteostasis (1)
- Proton-proton collisions (1)
- Proton–proton (1)
- Psychiatry (1)
- QGP (1)
- Quark Deconfinement (1)
- Quark Production (1)
- Quark gluon plasma (1)
- Quark–gluon plasma (1)
- Rapidity Range (1)
- Regulation of lipid metabolism (1)
- Rehabilitation (1)
- Relativistic heavy ion physics (1)
- Research article (1)
- Resolution Parameter (1)
- Resonances (1)
- STAR (1)
- Schock <Wirtschaft> (1)
- Seasonal variation (1)
- Shear viscosity (1)
- Single muons (1)
- SoftDrop (1)
- Solar insolation (1)
- Spin alignment (1)
- Splitting function (1)
- Strangeness enhancement (1)
- Stress response (1)
- Suicide (1)
- Sunlight (1)
- Surgery (1)
- Systematic Uncertainty (1)
- T-cells (1)
- TR (1)
- Technical data (1)
- Testen (1)
- Tetrahydrobiopterin (1)
- Time Projection Chamber (1)
- Time Projection Chamber (TPC) (1)
- Tracking (1)
- Transition radiation detector (1)
- Transverse momentum (1)
- Transversity (1)
- Trigger (1)
- Ubiquitin (1)
- Vector Boson Production (1)
- Vegetationstabellen (1)
- Verhaltensökonomie (1)
- Wide rapidity coverage (1)
- Xenon-based gas mixture (1)
- behavioral macroeconomics (1)
- dE/dx (1)
- detector (1)
- event pileup (1)
- experimental economics (1)
- experimental results (1)
- heavy ion experiments (1)
- heavy-ion collisions; (1)
- interactive visualization (1)
- p+p collisions (1)
- quark gluon plasma (1)
- space charge distortions (1)
- spectra (1)
- strategic complementarity (1)
- tracking (1)
- vegetationskundliche Software (1)
- √sN N = 2.76 TeV (1)
Institute
- Physik (1192)
- Frankfurt Institute for Advanced Studies (FIAS) (1109)
- Informatik (1003)
- Biochemie, Chemie und Pharmazie (5)
- Biochemie und Chemie (4)
- Medizin (4)
- Buchmann Institut für Molekulare Lebenswissenschaften (BMLS) (3)
- Informatik und Mathematik (3)
- MPI für Biophysik (3)
- Extern (2)
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)1. These partons subsequently emit further partons in a process that can be described as a parton shower2, 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 emitter3. 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 techniques4,5 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.
We present a study of the inclusive charged-particle transverse momentum (pT) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, dNch/dη, in pp collisions at s√=5.02 and 13 TeV covering the kinematic range |η|<0.8 and 0.15<pT<20 GeV/c. The results are presented for events with at least one charged particle in |η|<1 (INEL>0). The pT spectra are reported for two multiplicity estimators covering different pseudorapidity regions. The pT spectra normalized to that for INEL>0 show little energy dependence. Moreover, the high-pT yields of charged particles increase faster than the charged-particle multiplicity density. The average pT as a function of multiplicity and transverse spherocity is reported for pp collisions at s√=13 TeV. For low- (high-) spherocity events, corresponding to jet-like (isotropic) events, the average pT is higher (smaller) than that measured in INEL>0 pp collisions. Within uncertainties, the functional form of ⟨pT⟩(Nch) is not affected by the spherocity selection. While EPOS LHC gives a good description of many features of data, PYTHIA overestimates the average pT in jet-like events.
J/ψ production as a function of charged-particle multiplicity in p-Pb collisions at √sNN = 8.16 TeV
(2020)
Inclusive J/ψ yields and average transverse momenta in p-Pb collisions at a center-of-mass energy per nucleon pair s NN $$ \sqrt{s_{\mathrm{NN}}} $$ = 8.16 TeV are measured as a function of the charged-particle pseudorapidity density with ALICE. The J/ψ mesons are reconstructed at forward (2.03 < y cms < 3.53) and backward (−4.46 < y cms < −2.96) center-of-mass rapidity in their dimuon decay channel while the charged-particle pseudorapidity density is measured around midrapidity. The J/ψ yields at forward and backward rapidity normalized to their respective average values increase with the normalized charged-particle pseudorapidity density, the former showing a weaker increase than the latter. The normalized average transverse momenta at forward and backward rapidity manifest a steady increase from low to high charged-particle pseudorapidity density with a saturation beyond the average value.
The energy deposited at very forward rapidities (very forward energy) is a powerful tool for characterising proton fragmentation in pp and p-Pb collisions. The correlation of very forward energy with particle production at midrapidity provides direct insights into the initial stages and the subsequent evolution of the collision. Furthermore, the correlation with the production of particles with large transverse momenta at midrapidity provides information complementary to the measurements of the underlying event, which are usually interpreted in the framework of models implementing centrality-dependent multiple parton interactions.
Results about very forward energy, measured by the ALICE zero degree calorimeters (ZDCs), and its dependence on the activity measured at midrapidity in pp collisions at s√ = 13 TeV and in p-Pb collisions at sNN−−−√ = 8.16 TeV are discussed. The measurements performed in pp collisions are compared with the expectations of three hadronic interaction event generators: PYTHIA 6 (Perugia 2011 tune), PYTHIA 8 (Monash tune), and EPOS LHC. These results provide new constraints on the validity of models in describing the beam remnants at very forward rapidities, where perturbative QCD cannot be used.
Understanding the production mechanism of light (anti)nuclei is one of the key challenges of nuclear physics and has important consequences for astrophysics, since it provides an input for indirect dark-matter searches in space. In this paper, the latest results about the production of light (anti)nuclei in pp collisions at s√ = 13 TeV are presented, focusing on the comparison with the predictions of coalescence and thermal models. For the first time, the coalescence parameters B2 for deuterons and B3 for helions are compared with parameter-free theoretical predictions that are directly constrained by the femtoscopic measurement of the source radius in the same event class. A fair description of the data with a Gaussian wave function is observed for both deuteron and helion, supporting the coalescence mechanism for the production of light (anti)nuclei in pp collisions. This method paves the way for future investigations of the internal structure of more complex nuclear clusters, including the hypertriton.
Two-particle Azimuthal correlations are measured with the ALICE apparatus in pp collisions at s√=13 TeV to explore strangeness- and multiplicity-related effects in the fragmentation of jets and the transition regime between bulk and hard production, probed with the condition that a strange meson (KS0) or baryon (Λ) with transverse momentum pT>3 GeV/c is produced. Azimuthal correlations between kaons or Λ hyperons with other hadrons are presented at midrapidity for a broad range of the trigger (3<ptriggT<20 GeV/c) and associated particle pT (1 GeV/c <passocT<ptriggT), for minimum-bias events and as a function of the event multiplicity. The near- and away-side peak yields are compared for the case of either KS0 or Λ(Λ¯¯¯¯) being the trigger particle with that of inclusive hadrons (a sample dominated by pions). In addition, the measurements are compared with predictions from PYTHIA 8 and EPOS LHC event generators.
Angular correlations of heavy-flavour and charged particles in high-energy proton–proton collisions are sensitive to the production mechanisms of heavy quarks and to their fragmentation as well as hadronisation processes. The measurement of the azimuthal-correlation function of prompt D mesons with charged particles in proton–proton collisions at a centre-of-mass energy of s√=13 TeV with the ALICE detector is reported, considering D0, D+, and D∗+ mesons in the transverse-momentum interval 3<pT<36 GeV/c at midrapidity (|y|<0.5), and charged particles with pT>0.3 GeV/c and pseudorapidity |η|<0.8. This measurement has an improved precision and provides an extended transverse-momentum coverage compared to previous ALICE measurements at lower energies. The study is also performed as a function of the charged-particle multiplicity, showing no modifications of the correlation function with multiplicity within uncertainties. The properties and the transverse-momentum evolution of the near- and away-side correlation peaks are studied and compared with predictions from various Monte Carlo event generators. Among those considered, PYTHIA8 and POWHEG+PYTHIA8 provide the best description of the measured observables. The obtained results can provide guidance on tuning the generators.
The ALICE Collaboration reports the first fully-corrected measurements of the N-subjettiness observable for track-based jets in heavy-ion collisions. This study is performed using data recorded in pp and Pb-Pb collisions at centre-of-mass energies of s√ = 7 TeV and sNN−−−√ = 2.76 TeV, respectively. In particular the ratio of 2-subjettiness to 1-subjettiness, τ2/τ1, which is sensitive to the rate of two-pronged jet substructure, is presented. Energy loss of jets traversing the strongly interacting medium in heavy-ion collisions is expected to change the rate of two-pronged substructure relative to vacuum. The results are presented for jets with a resolution parameter of R = 0.4 and charged jet transverse momentum of 40 ≤ pT,jet ≤ 60 GeV/c, which constitute a larger jet resolution and lower jet transverse momentum interval than previous measurements in heavy-ion collisions. This has been achieved by utilising a semi-inclusive hadron-jet coincidence technique to suppress the larger jet combinatorial background in this kinematic region. No significant modification of the τ2/τ1 observable for track-based jets in Pb-Pb collisions is observed relative to vacuum PYTHIA6 and PYTHIA8 references at the same collision energy. The measurements of τ2/τ1, together with the splitting aperture angle ∆R, are also performed in pp collisions at s√ = 7 TeV for inclusive jets. These results are compared with PYTHIA calculations at s√ = 7 TeV, in order to validate the model as a vacuum reference for the Pb-Pb centre-of-mass energy. The PYTHIA references for τ2/τ1 are shifted to larger values compared to the measurement in pp collisions. This hints at a reduction in the rate of two-pronged jets in Pb-Pb collisions compared to pp collisions.
Measurement of the production of charm jets tagged with D0 mesons in pp collisions at √s = 7 TeV
(2019)
The production of charm jets in proton-proton collisions at a center-of-mass energy of s√=7 TeV was measured with the ALICE detector at the CERN Large Hadron Collider. The measurement is based on a data sample corresponding to a total integrated luminosity of 6.23 nb−1, collected using a minimum-bias trigger. Charm jets are identified by the presence of a D0 meson among their constituents. The D0 mesons are reconstructed from their hadronic decay D0 →K−π+. The D0-meson tagged jets are reconstructed using tracks of charged particles (track-based jets) with the anti-kT algorithm in the jet transverse momentum range 5<pchT,jet< 30 GeV/c and pseudorapidity |ηjet| < 0.5. The fraction of charged jets containing a D0-meson increases with pchT,jet from 0.042 ± 0.004 (stat) ± 0.006 (syst) to 0.080 ± 0.009 (stat) ± 0.008 (syst). The distribution of D0-meson tagged jets as a function of the jet momentum fraction carried by the D0 meson in the direction of the jet axis (zch∥) is reported for two ranges of jet transverse momenta, 5<pchT,jet< 15 GeV/c and 15<pchT,jet< 30 GeV/c in the intervals 0.2<zch∥∥<1.0 and 0.4<zch∥∥<1.0, respectively. The data are compared with results from Monte Carlo event generators (PYTHIA 6, PYTHIA 8 and Herwig 7) and with a Next-to-Leading-Order perturbative Quantum Chromodynamics calculation, obtained with the POWHEG method and interfaced with PYTHIA 6 for the generation of the parton shower, fragmentation, hadronisation and underlying event.
Production of pions, kaons, (anti-)protons and φ mesons in Xe–Xe collisions at √sNN = 5.44 TeV
(2021)
The first measurement of the production of pions, kaons, (anti-)protons and φ mesons at midrapidity in Xe–Xe collisions at √sNN = 5.44 TeV is presented. Transverse momentum (pT) spectra and pT-integrated yields are extracted in several centrality intervals bridging from p–Pb to mid-central Pb–Pb collisions in terms of final-state multiplicity. The study of Xe–Xe and Pb–Pb collisions allows systems at similar charged-particle multiplicities but with different initial geometrical eccentricities to be investigated. A detailed comparison of the spectral shapes in the two systems reveals an opposite behaviour for radial and elliptic flow. In particular, this study shows that the radial flow does not depend on the colliding system when compared at similar charged-particle multiplicity. In terms of hadron chemistry, the previously observed smooth evolution of particle ratios with multiplicity from small to large collision systems is also found to hold in Xe–Xe. In addition, our results confirm that two remarkable features of particle production at LHC energies are also valid in the collision of medium-sized nuclei: the lower proton-to-pion ratio with respect to the thermal model expectations and the increase of the φ-to-pion ratio with increasing final-state multiplicity.