ALICE measures the radial jet-energy flow observable Δp_T in Pb-Pb (5.02 TeV) and pp (13 TeV) collisions and reports narrowing of the energy distribution in heavy-ion collisions at 3.5-4.5σ significance.
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Tuning PYTHIA 8.1: the Monash 2013 Tune
Mixed citation behavior. Most common role is background (58%).
abstract
We present an updated set of parameters for the PYTHIA 8 event generator. We reevaluate the constraints imposed by LEP and SLD on hadronization, in particular with regard to heavy-quark fragmentation and strangeness production. For hadron collisions, we combine the updated fragmentation parameters with a new NNPDF2.3 LO PDF set. We use minimum-bias, Drell-Yan, and underlying-event data from the LHC to constrain the initial-state-radiation and multi-parton-interaction parameters, combined with data from SPS and the Tevatron to constrain the energy scaling. Several distributions show significant improvements with respect to the current defaults, for both ee and pp collisions, though we emphasize that interesting discrepancies remain in particular for strange particles and baryons. The updated parameters are available as an option starting from PYTHIA 8.185, by setting Tune:ee = 7 and Tune:pp = 14.
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representative citing papers
First measurement of D0-tagged jet angularities in pp collisions at 5.02 TeV shows smaller values at low angular weight, consistent with the QCD dead-cone effect for massive quarks.
First measurement of two-point EEC in 20-80 GeV/c charged jets in p-Pb collisions shows modification relative to pp at the same energy, with enhancement at large angles and suppression at small angles in the 20-40 GeV/c range.
Charged energy correlators measured in jets at the LHC show like-sign pairs sensitive to parton shower models and unlike-sign pairs sensitive to hadronization, with charge-independent cold nuclear matter effects in p-Pb collisions.
A model of quantum decoherence from string breaking explains hyperon spin correlations by linking vacuum entanglement to observed data in non-perturbative QCD.
PanScales final-state showers now include quark masses at NLL accuracy while keeping original accuracy for massless observables.
Bayesian constraints on early-time jet quenching from large collision systems yield predictions of measurable energy loss in oxygen-oxygen collisions.
Self-normalized yields of prompt and non-prompt J/ψ increase stronger than linearly with charged-particle multiplicity in pp collisions at 13 TeV, with stronger effect in the toward azimuthal region.
IRC-safe optimal-transport metrics (EMD, sEMD) enable lower-bias cell resampling of negative-weight NLO Monte Carlo events without intermediate jet clustering.
First estimates place inclusive branching ratios for antideuteron production from Lambda_b decays between 5.7e-4 and 1.4e-3 and from B- decays between 7.4e-6 and 4.3e-5, depending on hadronization scenario.
Spectral-function features fed to a dense network improve expected gluino-mass reach by ~150 GeV over ATLAS Gtt-0L-C and ~250 GeV over kinematics-only ML for the fully hadronic channel.
A reweighting method is introduced to efficiently study and tune MPI and CR parameter variations in Sherpa using relative weights, demonstrated with LHC and Tevatron data.
The authors define a generalised-k_t jet algorithm family for DIS in the Breit frame, extending the prior p=0 case, and test its use for struck-quark jet identification and non-perturbative effects.
NLO QCD plus parton-shower matched implementation for VBF Higgs plus photon production, with studies showing small shower effects on Higgs observables and larger effects on sub-leading jets.
Top quark mass measured at 172.17 ± 1.56 GeV via unbinned maximum-likelihood fit to m(ℓ μ⁺μ⁻) in ATLAS Run 2 data using J/ψ decays.
Search for narrow dijet resonances in the 0.6-1.8 TeV mass range with data scouting in 117 fb^{-1} of 13 TeV data finds no significant signal and sets model-independent upper limits on various resonance types and dark matter mediator couplings.
A deep neural network interpolates and extrapolates proton-proton reference transverse-momentum spectra to unmeasured center-of-mass energies using ALICE LHC data.
The first measurement of charged-particle dijet invariant mass spectra shows no significant nuclear modification in p-Pb collisions at low masses.
Proposes construction of the Forward Physics Facility at the HL-LHC with four complementary detectors to exploit forward neutrinos and new-particle fluxes for neutrino, QCD, astroparticle, and dark-matter measurements.
ATLAS reports the first measurement of the complete angular coefficients and pT-differential cross sections for W+ and W- bosons in full lepton phase space at 13 TeV, finding agreement with QCD predictions up to order α_S².
SemiCharmTag rejects charm-semileptonic muon background under LHCb dimuon Drell–Yan by secondary-vertex tagging with a hadron track, improving S/B by ~4 at 81% signal efficiency in simulation.
Updated non-relativistic Green's function formalism for ttbar threshold production gives a below-threshold cross section of order 6.5 pb matching recent LHC excess observations.
DeepMET is a neural-network-based missing transverse momentum estimator that improves resolution by 10-30% over existing CMS methods across a range of final states.
Effective TMD parton distributions are derived from PYTHIA8 and HERWIG6 parton showers and compared with those from the Parton Branching method.
citing papers explorer
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Modification of jet-energy flow in heavy-ion collisions
ALICE measures the radial jet-energy flow observable Δp_T in Pb-Pb (5.02 TeV) and pp (13 TeV) collisions and reports narrowing of the energy distribution in heavy-ion collisions at 3.5-4.5σ significance.
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Probing flavor effects in the QCD parton shower using $\mathbf{{\rm D}^0}$-tagged jet angularities in proton$-$proton collisions at $\mathbf{ \sqrt{s} = 5.02}$ TeV
First measurement of D0-tagged jet angularities in pp collisions at 5.02 TeV shows smaller values at low angular weight, consistent with the QCD dead-cone effect for massive quarks.
-
Energy-energy correlators in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV
First measurement of two-point EEC in 20-80 GeV/c charged jets in p-Pb collisions shows modification relative to pp at the same energy, with enhancement at large angles and suppression at small angles in the 20-40 GeV/c range.
-
Probing jet evolution with charged energy correlators in small systems
Charged energy correlators measured in jets at the LHC show like-sign pairs sensitive to parton shower models and unlike-sign pairs sensitive to hadronization, with charge-independent cold nuclear matter effects in p-Pb collisions.
-
Quantum decoherence of hyperon spin correlations in QCD hadronization
A model of quantum decoherence from string breaking explains hyperon spin correlations by linking vacuum entanglement to observed data in non-perturbative QCD.
-
Logarithmically-accurate showers with massive quarks
PanScales final-state showers now include quark masses at NLL accuracy while keeping original accuracy for massless observables.
-
Bayesian Constraints on Pre-Equilibrium Jet Quenching and Predictions for Oxygen Collisions
Bayesian constraints on early-time jet quenching from large collision systems yield predictions of measurable energy loss in oxygen-oxygen collisions.
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Multiplicity dependence of prompt and non-prompt J/$\psi$ production at midrapidity in pp collisions at $\sqrt{s} = 13$ TeV
Self-normalized yields of prompt and non-prompt J/ψ increase stronger than linearly with charged-particle multiplicity in pp collisions at 13 TeV, with stronger effect in the toward azimuthal region.
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Optimal-Transport-Based Cell Resampling for Negative and Pathological Event Weights
IRC-safe optimal-transport metrics (EMD, sEMD) enable lower-bias cell resampling of negative-weight NLO Monte Carlo events without intermediate jet clustering.
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Antideuteron production from beauty-hadron decays: a first phenomenological study
First estimates place inclusive branching ratios for antideuteron production from Lambda_b decays between 5.7e-4 and 1.4e-3 and from B- decays between 7.4e-6 and 4.3e-5, depending on hadronization scenario.
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Machine learning fully hadronic events with spectral functions
Spectral-function features fed to a dense network improve expected gluino-mass reach by ~150 GeV over ATLAS Gtt-0L-C and ~250 GeV over kinematics-only ML for the fully hadronic channel.
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Reweighting Underlying Event and Colour Reconnection parameter variations in Sherpa
A reweighting method is introduced to efficiently study and tune MPI and CR parameter variations in Sherpa using relative weights, demonstrated with LHC and Tevatron data.
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A generalised-$k_t$ jet algorithm for Deep Inelastic Scattering
The authors define a generalised-k_t jet algorithm family for DIS in the Breit frame, extending the prior p=0 case, and test its use for struck-quark jet identification and non-perturbative effects.
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NLO QCD and parton-shower effects for Higgs-boson production in association with a hard photon via vector-boson fusion
NLO QCD plus parton-shower matched implementation for VBF Higgs plus photon production, with studies showing small shower effects on Higgs observables and larger effects on sub-leading jets.
-
Measurement of the top-quark mass using decays with a $J/\psi$ meson at $\sqrt{s}=$13 TeV with the ATLAS detector
Top quark mass measured at 172.17 ± 1.56 GeV via unbinned maximum-likelihood fit to m(ℓ μ⁺μ⁻) in ATLAS Run 2 data using J/ψ decays.
-
Search for dijet resonances with data scouting in proton-proton collisions at $\sqrt{s}$ = 13 TeV
Search for narrow dijet resonances in the 0.6-1.8 TeV mass range with data scouting in 117 fb^{-1} of 13 TeV data finds no significant signal and sets model-independent upper limits on various resonance types and dark matter mediator couplings.
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DNN predictions for pp reference $p_\mathrm{T}$ spectra at unmeasured $\sqrt{s}$
A deep neural network interpolates and extrapolates proton-proton reference transverse-momentum spectra to unmeasured center-of-mass energies using ALICE LHC data.
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Dijet invariant mass of charged-particle jets in pp and p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV
The first measurement of charged-particle dijet invariant mass spectra shows no significant nuclear modification in p-Pb collisions at low masses.
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Letter of Intent: The Forward Physics Facility
Proposes construction of the Forward Physics Facility at the HL-LHC with four complementary detectors to exploit forward neutrinos and new-particle fluxes for neutrino, QCD, astroparticle, and dark-matter measurements.
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Measurement of the $W$-boson angular coefficients and transverse momentum in $pp$ collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector
ATLAS reports the first measurement of the complete angular coefficients and pT-differential cross sections for W+ and W- bosons in full lepton phase space at 13 TeV, finding agreement with QCD predictions up to order α_S².
-
SemiCharmTag: a tool for Semileptonic Charm tagging
SemiCharmTag rejects charm-semileptonic muon background under LHCb dimuon Drell–Yan by secondary-vertex tagging with a hadron track, improving S/B by ~4 at 81% signal efficiency in simulation.
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Top Pair Threshold Revisited
Updated non-relativistic Green's function formalism for ttbar threshold production gives a below-threshold cross section of order 6.5 pb matching recent LHC excess observations.
-
DeepMET: Improving missing transverse momentum estimation with a deep neural network
DeepMET is a neural-network-based missing transverse momentum estimator that improves resolution by 10-30% over existing CMS methods across a range of final states.
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TMD parton distributions from parton showers
Effective TMD parton distributions are derived from PYTHIA8 and HERWIG6 parton showers and compared with those from the Parton Branching method.
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Quantum Chromodynamics Monte Carlo Tuning Studies in CMS
New CMS PYTHIA 8 tunes using NLO or NNLO PDFs describe minimum-bias, underlying-event, and jet data in top-quark pair events at a level comparable to LO-based tunes.
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Proton-Proton to Antinucleon Cross Sections for Cosmic Ray Applications
NLO perturbative QCD calculations predict only a mild few-percent excess of antineutrons over antiprotons in pp collisions, not supporting the ~30% excess reported by NA49.
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Measurement of isolated-prompt photon$-$hadron correlations in Pb$-$Pb collisions at $\mathbf{\sqrt{\textit{s}_{\rm NN}} = 5.02}$ TeV
ALICE observes strong suppression of associated hadron yields per trigger photon in central Pb-Pb collisions at 5.02 TeV, extending the kinematic reach of photon-hadron correlation measurements.
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An Introduction to PYTHIA 8.2
PYTHIA 8.2 is a mature C++ event generator that combines hard processes, parton showers, multiparton interactions, and string fragmentation into a complete simulation framework for high-energy collisions.
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Inclusive and differential measurements of the $\mathrm{t\bar{t}}\gamma$ cross section and the $\mathrm{t\bar{t}}\gamma$ / $\mathrm{t\bar{t}}$ cross section ratio in proton-proton collisions at $\sqrt{s}$ = 13 TeV
CMS reports fiducial and differential ttγ cross sections plus ttγ/tt ratios at 13 TeV that agree with Standard Model expectations within uncertainties.
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Monte Carlo Event Generators for Future Lepton Colliders
Reviews selected challenges in Monte Carlo event generators for future lepton colliders including electroweak corrections, initial-state radiation, beam dynamics, perturbative QCD and non-perturbative modelling.
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The Monte Carlo Ecosystem in High-Energy Physics: A Primer
A primer by six leading developers maps the full Monte Carlo chain (matrix elements, parton showers, hadronisation, detector simulation, tuning, analysis) and the computing and reproducibility issues that come with it.
- Looking inside jets: an introduction to jet substructure and boosted-object phenomenology