Reconstruction of bottomonium spectral functions in thermal QCD using Kernel Ridge Regression

Offler, Sam; Aarts, Gert; Allton, Chris; Jäger, Benjamin; Kim, Seyong; Lombardo, Maria-Paola; Page, Benjamin John; Ryan, Sinead M.; Skullerud, Jon-Ivar; Spriggs, Thomas

doi:10.48550/arxiv.2112.02116

Cited by 3 publications

(5 citation statements)

References 11 publications

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“…So far, a clear picture has not emerged yet; applied to the same correlators, the mass shifts may be positive or negative, and the widths do not reveal a pattern consistent between the various methods, as indicated in Fig. 3; preliminary results were discussed at this conference [53][54][55] and summarized in further conference proceedings [56].…”

Section: Pos(lattice2021)014mentioning

confidence: 96%

“…The HotQCD results [50][51][52]59] using extended sources generally support the strong-binding scenario. Older results from FASTSUM [48] or HotQCD [49] as well as preliminary FASTSUM results [53][54][55][56]60] with local point sources paint a less conclusive picture. Thermal Wilson loops or Coulomb gauge Wilson line correlators have been analyzed by the HotQCD collaboration [58].…”

Section: Pos(lattice2021)014mentioning

confidence: 96%

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Heavy quarks at finite temperature

Weber¹

2022

Proceedings of the 38th International Symposium on Lattice Field Theory — PoS(LATTICE2021)

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New incarnations of heavy-ion collision experiments are turning our attention to hard processes and a more fine-grained resolution of the QGP. In this endeavor quarkonia or open heavy flavors turn out to be versatile probes, which are usually described through models based on perturbative QCD, AdS, and effective field theories. The lattice provides nonperturbative input and constraints to such models. In-medium bottomonia, the complex static quark-antiquark potential, and the heavy-quark momentum diffusion coefficient are key quantities where lattice gauge theory has recently achieved significant progress with impact for heavy-ion phenomenology. We review these lattice results, relate them to phenomenological applications, and close with an outlook.

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Section: Pos(lattice2021)014mentioning

confidence: 96%

Section: Pos(lattice2021)014mentioning

confidence: 96%

Heavy quarks at finite temperature

Weber¹

2022

Proceedings of the 38th International Symposium on Lattice Field Theory — PoS(LATTICE2021)

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“…As can be seen, the mock data tracks the actual correlators well. More details can be found in [16].…”

Section: Kernel Ridge Regressionmentioning

confidence: 99%

“…It is noted that the mass of both the ground state and first excited state lie below the experimental values. Further discussion is presented in [11,16].…”

Section: Kernel Ridge Regressionmentioning

confidence: 99%

A comparison of spectral reconstruction methods applied to non-zero temperature NRQCD meson correlation functions

Spriggs,

Aarts,

Allton

et al. 2021

Preprint

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We present results from the fastsum collaboration's programme to determine the spectrum of the bottomonium system as a function of temperature. Three different methods of extracting spectral information are discussed: a Maximum Likelihood approach using a Gaussian spectral function for the ground state, the Backus Gilbert method, and the Kernel Ridge Regression machine learning procedure. We employ the fastsum anisotropic lattices with 2+1 dynamical quark flavours, with temperatures ranging from 47 to 375 MeV.

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“…Other approaches include Maximum Likelihood methods using multi-exponential fitting [49] and also Kernel Ridge Regression (KRR) [50]. Thus far, each of the aforementioned methods provide differing predictions for the bottomonium spectrum at finite temperature.…”

Section: Techniques For Spectral Reconstructionmentioning

confidence: 99%

Novel approaches to the study of the heavy meson spectrum at finite temperature

Page

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This thesis is structured in three broad sections. The ﬁrst presents a brief intro-duction to the ﬁeld of quantum chromodynamics (QCD) and regularisation methods, which precedes a more thorough description of the lattice ﬁeld theoretic approach to QCD and its non-relativistic formalism, NRQCD, which is used in the analysis contained within this document. The second section introduces the ﬁrst problem of interest, spectral reconstruction in the case of bottomonium mesons. We focus in particular on the Laplacian nature of the problem and present the Backus-Gilbert method as a means of pro-ducing regularised solutions. The resolving power of the method is discussed and the overall approach is then extended with the inclusion of a novel technique known as Laplace shifting, which takes advantage of the structure of the problem to pro-vide a controlled resolution improvement to the method. A study of this technique is presented and applied to results obtained from Fastsum’s anisotropic NRQCD ensembles from which connections with a known phenomenon in Monte-Carlo based physics called Parisi-Lepage statistical scaling are elucidated. The third and ﬁnal section focuses on probing the temperature dependence of the gluon propagator again calculated using the Fastsum Gen-2L ensembles. We begin by showing results for the propagator in the Coulomb gauge, before extending to the Landau gauge where we discuss the necessary modiﬁcations to support the lattice anisotropy.

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Reconstruction of bottomonium spectral functions in thermal QCD using Kernel Ridge Regression

Cited by 3 publications

References 11 publications

Heavy quarks at finite temperature

Heavy quarks at finite temperature

A comparison of spectral reconstruction methods applied to non-zero temperature NRQCD meson correlation functions

Novel approaches to the study of the heavy meson spectrum at finite temperature

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