Production of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>J</mml:mi><mml:mo stretchy="false">/</mml:mo><mml:mi>ψ</mml:mi><mml:mo>+</mml:mo><mml:msub><mml:mrow><mml:mi>χ</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>J</mml:mi><mml:mo stretchy="false">/</mml:mo><mml:mi>ψ</mml:mi><mml:mo>+</mml:mo><mml:mi>J</mml:mi><mml:mo st

Лиходед, А. К.; Luchinsky, A. V.; Poslavsky, S. V.

doi:10.1103/physrevd.94.054017

Cited by 38 publications

(36 citation statements)

References 64 publications

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“…The theory normalisation is not used in the fits. The DPS fraction f DPS is defined as is smaller than expectations from the NLO * CS [70,[93][94][95][96] and NLO CS [39] approaches and roughly agrees with the NLO * CS [92] and LO k T [102] predictions. The value σ DPS determined with eq.…”

Section: Results and Comparison To Theorysupporting

confidence: 66%

“…The data can be reasonably well described with a sum of DPS and SPS colour-singlet contributions, with no evidence for a large SPS colour-octet contribution. The obtained SPS contribution is overestimated in the NLO * CS [70,[93][94][95][96] and NLO CS [39] approaches and roughly agrees with the NLO * CS [92] and LO k T [102] predictions. Good agreement with the data for the differential cross-sections calculated within the LO k T [102] and NLO * CS [92] approaches indicates that a significant part of high-order contributions can be properly accounted via the evolution of parton densities [102].…”

Section: Jhep06(2017)047 6 Summarysupporting

confidence: 81%

“…Theoretical predictions of the production cross-section of J/ψ pairs are summarized in table 2. The contribution from the SPS mechanism is calculated using several approaches: the state-of-art complete NLO colour-singlet (NLO CS) computations [39]; the incomplete (no-loops) next-to-leading-order colour-singlet (NLO * CS) calculations [70,[92][93][94][95][96]; leading-order colour-singlet (LO CS) [92] and colour-octet (LO CO) [95,96] calculations and the approach based on the k T -factorisation method [97][98][99][100][101], with the leading-order colour-singlet matrix element (LO k T ) [102,103]. Even with the leading-order matrix element, the LO k T approach includes a large fraction of higher-order contributions via the evolution of parton densities [102].…”

Section: Results and Comparison To Theorymentioning

confidence: 99%

“…Even with the leading-order matrix element, the LO k T approach includes a large fraction of higher-order contributions via the evolution of parton densities [102]. Since NLO * CS calculations are divergent at small transverse momentum of the J/ψ pair, two approaches are used: a simple cut-off for p T (J/ψ J/ψ ) [92] (denoted as NLO * CS ), and a cut on the mass of any light parton pair (NLO * CS ) [70,[93][94][95][96]. 7.5 ± 0.8…”

Section: Results and Comparison To Theorymentioning

confidence: 99%

“…The feed-down from ψ(2S) → J/ψ X decays is included in the LO k T , LO CO and NLO * CS calculations and not in the LO CS and NLO * CS calculations. Likewise, a tiny contribution from J/ψ χ c production with subsequent decay χ c → J/ψ γ [92] is included in the NLO * CS and LO CO results but neglected in the NLO * CS calculations.…”

Section: Results and Comparison To Theorymentioning

confidence: 99%

See 4 more Smart Citations

Measurement of the J/ψ pair production cross-section in pp collisions at s = 13 $$ \sqrt{s}=13 $$ TeV

Aaij¹,

Adeva²,

Adinolfi³

et al. 2017

J. High Energ. Phys.

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Abstract:The production cross-section of J/ψ pairs is measured using a data sample of pp collisions collected by the LHCb experiment at a centre-of-mass energy of √ s = 13 TeV, corresponding to an integrated luminosity of 279 ±11 pb −1 . The measurement is performed for J/ψ mesons with a transverse momentum of less than 10 GeV/c in the rapidity range 2.0 < y < 4.5. The production cross-section is measured to be 15.2 ± 1.0 ± 0.9 nb. The first uncertainty is statistical, and the second is systematic. The differential cross-sections as functions of several kinematic variables of the J/ψ pair are measured and compared to theoretical predictions.Keywords: Hadron-Hadron scattering (experiments), Particle and resonance production, proton-proton scattering, QCD, Quarkonium The LHCb collaboration 33 IntroductionThe production mechanism of heavy quarkonia is a long-standing and intriguing problem in quantum chromodynamics (QCD), which is not fully understood even after over forty years of study. The colour-singlet model (CSM) [1-10] assumes the intermediate QQ state to be colourless and to have the same J P C quantum numbers as the final quarkonium state. Leading-order calculations in the CSM underestimate the J/ψ and ψ(2S) production cross-sections at high transverse momentum, p T , by more than one order of magnitude [11]. The gap between CSM predictions and experimental measurements is reduced when including next-to-leading-order corrections, but the agreement is still not satisfactory [12][13][14]. The non-relativistic QCD (NRQCD) model takes into account both colour-singlet (CS) and colour-octet (CO) states of the QQ pair [15][16][17]. It either describes the production cross-sections and polarisations at large p T or it describes the production cross-section at all p T values, but then fails to predict the polarisation [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. This puzzle can be probed via the production of pairs of quarkonia [34][35][36][37][38][39], where the interpretation of the measured cross-section could be simpler. In quarkonium-pair production, the selection rules in the CS process of leading-order (LO) NRQCD forbid the feed-down from cascade decays of excited C-even states. This feed-down from C-even states, e.g. χ c → J/ψ γ or χ b → Υ γ, plays an important role in single quarkonium production. It significantly complicates the precise comparison between data and model predictions, and makes the interpretation of polarisation measurements difficult. Besides the single parton scattering (SPS) process, the process of double parton scattering (DPS) can also contribute to quarkonium pair production. The DPS process is of great -1 -

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Section: Results and Comparison To Theorysupporting

confidence: 66%

Section: Jhep06(2017)047 6 Summarysupporting

confidence: 81%

Section: Results and Comparison To Theorymentioning

confidence: 99%

Section: Results and Comparison To Theorymentioning

confidence: 99%

Section: Results and Comparison To Theorymentioning

confidence: 99%

See 3 more Smart Citations

Measurement of the J/ψ pair production cross-section in pp collisions at s = 13 $$ \sqrt{s}=13 $$ TeV

Aaij¹,

Adeva²,

Adinolfi³

et al. 2017

J. High Energ. Phys.

View full text Add to dashboard Cite

show abstract

Associated production of a quarkonium and a Z boson at one loop in a quark-hadron-duality approach

Lansberg

Shao

2016

J. High Energ. Phys.

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In view of the large discrepancy about the associated production of a prompt J/ψ and a Z boson between the ATLAS data at √ s = 8 TeV and theoretical predictions for Single Parton Scattering (SPS) contributions, we perform an evaluation of the corresponding cross section at one loop accuracy (Next-to-Leading Order, NLO) in a quarkhadron-duality approach, also known as the Colour-Evaporation Model (CEM). This work is motivated by (i) the extremely disparate predictions based on the existing NRQCD fits conjugated with the absence of a full NLO NRQCD computation and (ii) the fact that we believe that such an evaluation provides a likely upper limit of the SPS cross section. In addition to these theory improvements, we argue that the ATLAS estimation of the Double Parton Scattering (DPS) yield may be underestimated by a factor as large as 3 which then reduces the size of the SPS yield extracted from the ATLAS data. Our NLO SPS evaluation also allows us to set an upper limit on σ eff driving the size of the DPS yield. Overall, the discrepancy between theory and experiment may be smaller than expected, which calls for further analyses by ATLAS and CMS, for which we provide predictions, and for full NLO computations in other models. As an interesting side product of our analysis, we have performed the first NLO computation of dσ/dP T for prompt single-J/ψ production in the CEM from which we have fit the CEM non-pertubative parameter at NLO using the most recent ATLAS data.

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Next-to-leading order QCD corrections to paired B production in e+e− annihilation

et al. 2017

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We present theoretical analysis of paired B c mesons production in e + e − annihilation at different energy scales taking into account full next-to-leading order QCD corrections. Both possible electroweak channels are considered: production via virtual photon and via virtual Z-boson. We study in detail the role of radiative QCD corrections, which were found to be significant especially at low energies. It is shown that the contribution from Z-boson is significant at high energies ( √ s > M Z /2) especially in the case of paired production of pseudo-scalar and vector (B c + B * c ) mesons. Azimuthal asymmetry induced by a P-violating weak interaction with Z-boson is also analyzed. Email addresses: Alexander.Berezhnoy@cern.ch (A.V. Berezhnoy), Anatolii.Likhoded@ihep.ru (A.K. Likhoded), onish@bk.ru (A.I. Onishchenko), stvlpos@mail.ru (S.V. Poslavsky) NRQCD factorization and projectorsProduction and bound state dynamics of quarkonia involves several different energy scales. First, we have hard scales given by heavy quark masses m b and m c . Next, there are so called soft and ultrasoft scales. The soft scale is given by the relative momentum of heavy quark-antiquark pair in the quarkonium rest frame |p| ∼ mv (∼ 1/r). Here v is the relative velocity of quarkantiquark motion, r is the radius of quarkonium and m is the reduced mass, which in the case of B c meson is given by m = m c m b m c +m b . The ultrasoft scale is given by kinetic energy of quarkantiquark motion inside quarkonium E ∼ mv 2 and of course we have nonperturbative confinement scale Λ QCD . The nonrelativistic QCD (NRQCD) is the effective theory obtained by integrating out hard degrees of freedom from QCQ. The general hierarchy of scales for quarkonia production and bound state dynamics is m b , m c mv, mv 2 , Λ QCD , as v 1. First, it sets a firm ground

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Production ofJ/ψ+χcandJ/ψ+J

Cited by 38 publications

References 64 publications

Measurement of the J/ψ pair production cross-section in pp collisions at s = 13 $$ \sqrt{s}=13 $$ TeV

Measurement of the J/ψ pair production cross-section in pp collisions at s = 13 $$ \sqrt{s}=13 $$ TeV

Associated production of a quarkonium and a Z boson at one loop in a quark-hadron-duality approach

Next-to-leading order QCD corrections to paired B production in e+e− annihilation

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