HELAC-Onia 2.0: An upgraded matrix-element and event generator for heavy quarkonium physics

Shao, Hua-Sheng

doi:10.1016/j.cpc.2015.09.011

Cited by 136 publications

(114 citation statements)

References 108 publications

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“…Given that the underlying event at LHCb is well described by PYTHIA8, e.g., the energy flow is accurately predicted at the 5% level [57], the prompt-J=ψ results cannot be reconciled with this prediction. Furthermore, LO and partial next-to-leading-order (NLO*) calculations in both the color-singlet and color-octet models similarly fail to describe the data [52,58]. Prompt J=ψ mesons in data are observed to be much less isolated than predicted, which qualitatively agrees with the alternative picture of quarkonium production presented in Ref.…”

Section: H Y S I C a L R E V I E W L E T T E R S Week Ending 12 May 2017supporting

confidence: 79%

Study of J/ψ Production in Jets

Aaij¹,

Ciezarek²,

Collins³

et al. 2017

Phys. Rev. Lett.

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The production of J=ψ mesons in jets is studied in the forward region of proton-proton collisions using data collected with the LHCb detector at a center-of-mass energy of 13 TeV. The fraction of the jet transverse momentum carried by the J=ψ meson, zðJ=ψÞ ≡ p T ðJ=ψÞ=p T ðjetÞ, is measured using jets with p T ðjetÞ > 20 GeV in the pseudorapidity range 2.5 < ηðjetÞ < 4.0. The observed zðJ=ψÞ distribution for J=ψ mesons produced in b-hadron decays is consistent with expectations. However, the results for prompt J=ψ production do not agree with predictions based on fixed-order nonrelativistic QCD. This is the first measurement of the p T fraction carried by prompt J=ψ mesons in jets at any experiment.

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Section: H Y S I C a L R E V I E W L E T T E R S Week Ending 12 May 2017supporting

confidence: 79%

Study of J/ψ Production in Jets

Aaij¹,

Ciezarek²,

Collins³

et al. 2017

Phys. Rev. Lett.

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“…-25 - The tool is based on the HELAC-Onia package [95,96], originally developed for heavyquarkonium studies, recently extended to heavy-flavor mesons and baryons. Differently from other calculations shown in figure 9, this is therefore a prediction for p-Pb collisions based on pp data.…”

Section: Jhep04(2018)108mentioning

confidence: 99%

“…This calculation for p-Pb collisions underpredicts the measured values by a similar amount as observed in pp collisions. The Λ c cross section is also compared with a calculation [94], based on a data-driven modelling of the scattering at the partonic level, specifically designed to evaluate the impact of the nuclear modification of the gluon density on heavy-flavor hadrons.-25 - The tool is based on the HELAC-Onia package [95,96], originally developed for heavyquarkonium studies, recently extended to heavy-flavor mesons and baryons. Differently from other calculations shown in figure 9, this is therefore a prediction for p-Pb collisions based on pp data.…”

mentioning

confidence: 99%

Λ+c production in pp collisions at $$ \sqrt{s}=7 $$ TeV and in p-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}}=5.02 $$ TeV

Acharya¹,

Acosta²,

Adamová³

et al. 2018

J. High Energ. Phys.

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The p T -differential production cross section of prompt Λ + c charmed baryons was measured with the ALICE detector at the Large Hadron Collider (LHC) in pp collisions at √ s = 7 TeV and in p-Pb collisions at √ s NN = 5.02 TeV at midrapidity. The Λ + c and Λ -c were reconstructed in the hadronic decay modes Λ + c → pK − π + , Λ + c → pK 0 S and in the semileptonic channel Λ + c → e + ν e Λ (and charge conjugates). The measured values of the Λ + c /D 0 ratio, which is sensitive to the c-quark hadronisation mechanism, and in particular to the production of baryons, are presented and are larger than those measured previously in different colliding systems, centre-of-mass energies, rapidity and p T intervals, where the Λ + c production process may differ. The results are compared with the expectations obtained from perturbative Quantum Chromodynamics calculations and Monte Carlo event generators. Neither perturbative QCD calculations nor Monte Carlo models reproduce the data, indicating that the fragmentation of heavy-flavour baryons is not well understood. The first measurement at the LHC of the Λ + c nuclear modification factor, R pPb , is also presented. The R pPb is found to be consistent with unity and with that of D mesons within the uncertainties, and consistent with a theoretical calculation that includes cold nuclear matter effects and a calculation that includes charm quark interactions with a deconfined medium. Keywords: Heavy Ion Experiments, Quark gluon plasmaArXiv ePrint: 1712.09581Open Access, Copyright CERN, for the benefit of the ALICE Collaboration. Article funded by SCOAP 3 .https://doi.org/10.1007/JHEP04(2018)108 The ALICE collaboration 40 JHEP04(2018)108 IntroductionThe study of charm production at the Large Hadron Collider (LHC) is an important tool to test predictions obtained from perturbative Quantum Chromodynamics (pQCD) calculations for proton-proton (pp) collisions. These calculations are based on the factorisation approach that describes heavy-flavour production as a convolution of the parton distribution functions, the parton hard-scattering cross section and the fragmentation function. The cross section for heavy-flavour hadron production can be obtained from perturbative calculations at next-to-leading order with next-to-leading-log resummation, like the General-Mass Variable-Flavour-Number Scheme (GM-VFNS [1, 2]) and 4]) approaches. No predictions are, however, available for baryons in the latter approach due to lack of knowledge of the fragmentation function of charm quarks into baryons. Cross section calculations are available also with the k T factorisation framework [5]. These theoretical calculations generally describe within uncertainties the measurements at the LHC, with the central predictions for beauty production lying closer to data than the central predictions for charm production [6]. The measured -1 - JHEP04(2018)108transverse momentum differential cross section of charm mesons lies in the upper part of the FONLL uncertainty band and is systematically below th...

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“…As will be explained below, the tool which we propose is based on HELAC-Onia [43,44] (but is not restricted to quarkonia) can use any nPDF set included in the library LHAPDF5 [45,46] and LHAPDF6 [47] and does not rely on any model for the hard-probe production, but on pp measurements which are used to tune the partonic-scattering elements, keeping in mind the limitation that it should be tuned for each process and in principle for possible different kinematical region with the chosen proton PDF and factorisation scale.…”

Section: Introductionmentioning

confidence: 99%

Towards an automated tool to evaluate the impact of the nuclear modification of the gluon density on quarkonium, D and B meson production in proton–nucleus collisions

2016

Self Cite

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We propose a simple and model-independent procedure to account for the impact of the nuclear modification of the gluon density as encoded in nuclear collinear PDF sets on two-to-two partonic hard processes in protonnucleus collisions. This applies to a good approximation to quarkonium, D and B meson production, generically referred to H. Our procedure consists in parametrising the square of the parton scattering amplitude, A gg→HX and constraining it from the proton-proton data. Doing so, we have been able to compute the corresponding nuclear modification factors for J/ψ, ϒ and D 0 as a function of y and P T at √ s NN = 5 and 8 TeV in the kinematics of the various LHC experiments in a model independent way. It is of course justified since the most important ingredient in such evaluations is the probability of each kinematical configuration. Our computations for D mesons can also be extended to B meson production. To further illustrate the potentiality of the tool, we provide -for the first time -predictions for the nuclear modification factor for η c production in pPb collisions at the LHC.

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HELAC-Onia 2.0: An upgraded matrix-element and event generator for heavy quarkonium physics

Cited by 136 publications

References 108 publications

Study of J/ψ Production in Jets

Study of J/ψ Production in Jets

Λ+c production in pp collisions at $$ \sqrt{s}=7 $$ TeV and in p-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}}=5.02 $$ TeV

Towards an automated tool to evaluate the impact of the nuclear modification of the gluon density on quarkonium, D and B meson production in proton–nucleus collisions

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