An Unbiased Hessian Representation for Monte Carlo PDFs

Stefano Carrazza, Stefano Forte, Zahari Kassabov, Jose Ignacio Latorre, Juan Rojo

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

We develop a methodology for the construction of a Hessian representation of Monte Carlo sets of parton distributions, based on the use of a subset of the Monte Carlo PDF replicas as an unbiased linear basis, and of a genetic algorithm for the determination of the optimal basis. We validate the methodology by first showing that it faithfully reproduces a native Monte Carlo PDF set (NNPDF3.0), and then, that if applied to Hessian PDF set (MMHT14) which was transformed into a Monte Carlo set, it gives back the starting PDFs with minimal information loss. We then show that, when applied to a large Monte Carlo PDF set obtained as combination of several underlying sets, the methodology leads to a Hessian representation in terms of a rather smaller set of parameters (CMC-H PDFs), thereby providing an alternative implementation of the recently suggested Meta-PDF idea and a Hessian version of the recently suggested PDF compression algorithm (CMC-PDFs). The mc2hessian conversion code is made publicly available together with (through LHAPDF6) a Hessian representations of the NNPDF3.0 set, and the CMC-H PDF set.
Original languageEnglish
Article number369
JournalEuropean Physical Journal C. Particles and Fields
Volume75
Issue number8
DOIs
Publication statusPublished - 25 May 2015

Fingerprint

Genetic algorithms
methodology
replicas
genetic algorithms
partons
set theory

Bibliographical note

27 pages, 17 figures; v2: replaced plots in Fig.1 which had a conflict with google chrome inline viewer; v3: final version, to be published in EPJC; figs 5,10,11,13 updated with new (more accurate) choice of parameters

Keywords

  • hep-ph

Cite this

Carrazza, Stefano ; Forte, Stefano ; Kassabov, Zahari ; Latorre, Jose Ignacio ; Rojo, Juan. / An Unbiased Hessian Representation for Monte Carlo PDFs. In: European Physical Journal C. Particles and Fields. 2015 ; Vol. 75, No. 8.
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An Unbiased Hessian Representation for Monte Carlo PDFs. / Carrazza, Stefano; Forte, Stefano; Kassabov, Zahari; Latorre, Jose Ignacio; Rojo, Juan.

In: European Physical Journal C. Particles and Fields, Vol. 75, No. 8, 369, 25.05.2015.

Research output: Contribution to JournalArticleAcademicpeer-review

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