REVIEW
Perturbative QCD Fragmentation Functions as a Model for Heavy-Quark Fragmentation
High Energy Physics - Phenomenology · Submitted 15 Sep 1994 · 22 references
Pith's verdict: The HQET next-to-leading derivation is real, checkable work; the heavy-light model is a clearly-labeled ansatz, and the headline P_V(z) shape is more robust than the single fitted parameter behind it.
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The paper
The paper claims
Using heavy-quark effective theory, the authors extend perturbative QCD fragmentation functions to next-to-leading order in 1/m_Q and predict that the vector-meson fraction in a heavy-quark jet runs from about 1/2 at small z to about 3/4 near z = 1.
The reading
Extended reading notes
Core claim
The load-bearing claim is that the perturbative QCD fragmentation functions, taken as a two-parameter model, predict the vector-meson fraction P_V to run from about 1/2 at small longitudinal momentum fraction z to almost 3/4 near z = 1 (abstract s5; Section V and Fig. 4). The supporting derivation is the HQET computation of the next-to-leading 1/m_Q terms b(y) and b*(y) in Eqs. (28) and (30), which reproduces the m_b to infinity limit of the earlier PQCD result of Ref. [6] when C3 = 1. The nontrivial check is that the C2 terms cancel between propagator and vertex corrections, as the paper shows explicitly.
Load-bearing premise
The load-bearing premise is that the PQCD fragmentation functions computed for a heavy quark plus heavy antiquark (b-bar to B_c in Ref. [6]) can be transplanted to the heavy-light case by treating r as the ratio of a constituent light-quark mass to the meson mass (Section III, Eqs. 31 and 32). Nothing in the paper derives this; it is a modeling choice, and the fitted r_D = 0.10 (about 200 MeV constituent mass) is the only empirical anchor. If the heavy-light system requires dynamics not captured by the heavy-heavy template, the P_V(z) shape prediction loses its basis.
Original abstract
The perturbative QCD fragmentation functions for a heavy quark to fragment into heavy-light mesons are studied in the heavy-quark limit. The fragmentation functions for S-wave pseudoscalar and vector mesons are calculated to next-to-leading order in the heavy-quark mass expansion using the methods of heavy-quark effective theory. The results agree with the $m_b\to \infty$ limit of the perturbative QCD fragmentation functions for $\bar b$ into $B_c$ and $B_c^*$. We discuss the application of the perturbative QCD fragmentation functions as a model for the fragmentation of heavy quarks into heavy-light mesons. Using this model, we predict the fraction $P_{V}$ of heavy-light mesons that are produced in the vector meson state as functions of the longitudinal momentum fraction $z$ and the transverse momentum relative to the jet axis. The fraction $P_V$ is predicted to vary from about 1/2 at small $z$ to almost 3/4 near $z=1$.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
The perturbative QCD fragmentation functions for a heavy quark to fragment into heavy-light mesons are studied in the heavy-quark limit. The fragmentation functions for S-wave pseudoscalar and vector mesons are calculated to next-to-leading order in the heavy-quark mass expansion using the methods of heavy-quark effective theory. The results agree with the $m_b\to \infty$ limit of the perturbative QCD fragmentation functions for $\bar b$ into $B_c$ and $B_c^*$. We discuss the application of the perturbative QCD fragmentation functions as a model for the fragmentation of heavy quarks into heavy-light mesons. Using this model, we predict the fraction $P_{V}$ of heavy-light mesons that are produced in the vector meson state as functions of the longitudinal momentum fraction $z$ and the transverse momentum relative to the jet axis. The fraction $P_V$ is predicted to vary from about 1/2 at small $z$ to almost 3/4 near $z=1$.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The perturbative QCD fragmentation functions for a heavy quark to fragment into heavy-light mesons are studied in the heavy-quark limit. | contribution 0.93 | 0.76 | 0.07 | asserted 0.86 |
| s1 | The fragmentation functions for S-wave pseudoscalar and vector mesons are calculated to next-to-leading order in the heavy-quark mass expansion using the methods of heavy-quark effective theory. | method 0.67 | 0.91 | 0.09 | asserted 1.00 |
| s2 | The results agree with the $m_b\to \infty$ limit of the perturbative QCD fragmentation functions for $\bar b$ into $B_c$ and $B_c^*$. | result 0.97 | 0.73 | 0.20 | asserted 1.00 |
| s3 | We discuss the application of the perturbative QCD fragmentation functions as a model for the fragmentation of heavy quarks into heavy-light mesons. | contribution 0.53 | 0.81 | 0.12 | unclear 0.51 |
| s4 | Using this model, we predict the fraction $P_{V}$ of heavy-light mesons that are produced in the vector meson state as functions of the longitudinal momentum fraction $z$ and the transverse momentum relative to the jet axis. | contribution 0.62 | 0.91 | 0.20 | asserted 0.99 |
| s5 | The fraction $P_V$ is predicted to vary from about 1/2 at small $z$ to almost 3/4 near $z=1$. | result 1.00 | 0.91 | 0.45 | asserted 0.87 |
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References
How the literature uses it
32 arXiv papers cite this in 45 sentences
Papers citing it · 24 sentences without a confident label
Uses its method or tool 9 papers
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In EPOS4HQ, we use the heavy quark effective theory-based fragmentation function [ref] .
Heavy flavour hadron production in relativistic heavy ion collisions at RHIC and LHC in EPOS4HQ · Hadronization scheme · 1.00
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The boundary condition for heavy quark fragmentation into the various $D$-meson and $B$-meson states at a scale $μ= 2 m_Q$ can be calculated perturbatively using heavy quark effective theory (HQET), as shown in Refs. [ref] .
Heavy meson tomography of cold nuclear matter at the electron-ion collider · Hadron Production in DIS · 0.85
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We will employ here the BCFY [ref] and KKKS [ref] FFs; key details are discussed in Appendix [ref].
Event engineering studies for heavy flavor production and hadronization in high multiplicity hadron-hadron and hadron-nucleus collisions · Open flavor and Quarkonium production · 0.93
Uses its data or values 3 papers
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Due to the lack of FONLL predictions for the $$-meson production, the extrapolation factor was calculated using the $$-differential cross section of charm quarks provided by FONLL calculations, the fragmentation fractions $f(c→)$ and $f(c→D_s^*+)$ from ALEPH measurements [ref] , and the charm-quark fragmentation functions from Ref. [ref] .
Charm production and fragmentation fractions at midrapidity in pp collisions at $\sqrt{s} = 13$ TeV · Charm-hadron $$-integrated cross sections and extrapolation down to $=0$ · 0.97
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Initially, we presume that the momentum distribution of c-quarks is the prompt one obtained through Fixed Order + Next-to-Leading Log (FONLL) QCD, which describes the D-mesons spectra in pp collisions after fragmentation [ref] .
Energy loss of heavy quarks in the presence of magnetic field · Nuclear modification factor, $R_AA$ · 0.84
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In the case of $$ mesons, for which a FONLL prediction is not available, the central value of the extrapolation factor was computed from the prediction based on the $$-differential cross section of charm quarks from FONLL, the fractions $f(c→)$ and $f(c→D_s^*+)$ from ALEPH [ref] , and the fragmentation functions from [ref] , which have one parameter, $r$, that was set to 0.1 as done in FONLL [ref] .
Measurement of D-meson production at mid-rapidity in pp collisions at $\mathbf{\sqrt{s}=7}$ TeV · Results · 0.83
Cites it as background 7 papers
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The final $D$ mesons are formed through charm quark fragmentation at high $p_T$ [ref] or charm-light quark recombination at low and intermediate $p_T$ [ref] .
Hydrodynamic description of $D$ meson production in high-energy heavy-ion collisions · Charm meson production in the limit of local kinetic equilibrium · 0.91
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Ideas about heavy flavor fragmentation that do not involve data fits have also been put forward [ref] .
NNLO B-fragmentation fits and their application to $t\bar t$ production and decay at the LHC · Introduction · 0.98
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Typically, NPFFs are extracted from $e^+e^-$ data, however, theoretically motivated ones also exist [ref] .
B-hadron hadro-production in NNLO QCD: application to LHC $t\bar{t}$ events with leptonic decays · Perturbative and Non-Perturbative Fragmentation Functions for Heavy Flavor Fragmentation · 0.88
Discussion
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