Finding signatures of the nuclear symmetry energy in heavy-ion collisions with deep learning

Yongjia Wang (School of Science, Huzhou University, Huzhou, China) ; Fupeng Li (School of Science, Huzhou University, Huzhou, China; School of Science, Zhejiang University of Technology, Hangzhou, China) ; Qingfeng Li (School of Science, Huzhou University, Huzhou, China; Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China) ; Hongliang Lü (HiSilicon Research Department, Huawei Technologies Co., Ltd., Shenzhen, China) ; Kai Zhou (Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany)

A deep convolutional neural network (CNN) is developed to study symmetry energy (Esym(ρ)) effects by learning the mapping between the symmetry energy and the two-dimensional (transverse momentum and rapidity) distributions of protons and neutrons in heavy-ion collisions. Supervised training is performed with labeled data-set from the ultrarelativistic quantum molecular dynamics (UrQMD) model simulation. It is found that, by using proton spectra on event-by-event basis as input, the accuracy for classifying the soft and stiff Esym(ρ) is about 60% due to large event-by-event fluctuations, while by setting event-summed proton spectra as input, the classification accuracy increases to 98%. The accuracies for 5-label (5 different Esym(ρ)) classification task are about 58% and 72% by using proton and neutron spectra, respectively. For the regression task, the mean absolute errors (MAE) which measure the average magnitude of the absolute differences between the predicted and actual L (the slope parameter of Esym(ρ)) are about 20.4 and 14.8 MeV by using proton and neutron spectra, respectively. Fingerprints of the density-dependent nuclear symmetry energy on the transverse momentum and rapidity distributions of protons and neutrons can be identified by convolutional neural network algorithm.

{
  "license": [
    {
      "url": "http://creativecommons.org/licenses/by/3.0/", 
      "license": "CC-BY-3.0"
    }
  ], 
  "copyright": [
    {
      "holder": "The Author(s)", 
      "statement": "The Author(s)", 
      "year": "2021"
    }
  ], 
  "control_number": "64949", 
  "_oai": {
    "updated": "2021-10-26T06:43:26Z", 
    "id": "oai:repo.scoap3.org:64949", 
    "sets": [
      "PLB"
    ]
  }, 
  "authors": [
    {
      "surname": "Wang", 
      "given_names": "Yongjia", 
      "affiliations": [
        {
          "country": "China", 
          "value": "School of Science, Huzhou University, Huzhou, China"
        }
      ], 
      "full_name": "Wang, Yongjia", 
      "orcid": "0000-0003-2506-0010", 
      "email": "wangyongjia@zjhu.edu.cn"
    }, 
    {
      "affiliations": [
        {
          "country": "China", 
          "value": "School of Science, Huzhou University, Huzhou, China"
        }, 
        {
          "country": "China", 
          "value": "School of Science, Zhejiang University of Technology, Hangzhou, China"
        }
      ], 
      "surname": "Li", 
      "given_names": "Fupeng", 
      "full_name": "Li, Fupeng"
    }, 
    {
      "affiliations": [
        {
          "country": "China", 
          "value": "School of Science, Huzhou University, Huzhou, China"
        }, 
        {
          "country": "China", 
          "value": "Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China"
        }
      ], 
      "surname": "Li", 
      "email": "liqf@zjhu.edu.cn", 
      "full_name": "Li, Qingfeng", 
      "given_names": "Qingfeng"
    }, 
    {
      "affiliations": [
        {
          "country": "China", 
          "value": "HiSilicon Research Department, Huawei Technologies Co., Ltd., Shenzhen, China"
        }
      ], 
      "surname": "L\u00fc", 
      "given_names": "Hongliang", 
      "full_name": "L\u00fc, Hongliang"
    }, 
    {
      "orcid": "0000-0001-9859-1758", 
      "affiliations": [
        {
          "country": "Germany", 
          "value": "Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany"
        }
      ], 
      "surname": "Zhou", 
      "given_names": "Kai", 
      "full_name": "Zhou, Kai"
    }
  ], 
  "_files": [
    {
      "checksum": "md5:6e1c8dca46dcf3131cce29e6b4c2cf73", 
      "filetype": "xml", 
      "bucket": "01d455e2-3e37-41cb-9fd1-429e01e0cf37", 
      "version_id": "7e9351dd-b07b-428d-9d96-e86e73fa03b1", 
      "key": "10.1016/j.physletb.2021.136669.xml", 
      "size": 110366
    }, 
    {
      "checksum": "md5:aaca7a3965ddb9eb6045f7310ebc8dc8", 
      "filetype": "pdf", 
      "bucket": "01d455e2-3e37-41cb-9fd1-429e01e0cf37", 
      "version_id": "28c65eb9-f1d4-4dc4-a2bd-5542a0ca20b3", 
      "key": "10.1016/j.physletb.2021.136669.pdf", 
      "size": 678754
    }, 
    {
      "checksum": "md5:e3f798c82256b6d24b2712842e009d82", 
      "filetype": "pdf/a", 
      "bucket": "01d455e2-3e37-41cb-9fd1-429e01e0cf37", 
      "version_id": "c09f408c-2a60-4860-b314-e1dd20aeb9ed", 
      "key": "10.1016/j.physletb.2021.136669_a.pdf", 
      "size": 1028747
    }
  ], 
  "record_creation_date": "2021-09-28T15:30:22.647829", 
  "titles": [
    {
      "source": "Elsevier", 
      "title": "Finding signatures of the nuclear symmetry energy in heavy-ion collisions with deep learning"
    }
  ], 
  "collections": [
    {
      "primary": "Physics Letters B"
    }
  ], 
  "dois": [
    {
      "value": "10.1016/j.physletb.2021.136669"
    }
  ], 
  "publication_info": [
    {
      "journal_volume": "822 C", 
      "journal_title": "Physics Letters B", 
      "material": "article", 
      "artid": "136669", 
      "year": 2021
    }
  ], 
  "$schema": "http://repo.scoap3.org/schemas/hep.json", 
  "abstracts": [
    {
      "source": "Elsevier", 
      "value": "A deep convolutional neural network (CNN) is developed to study symmetry energy (<math><msub><mrow><mi>E</mi></mrow><mrow><mi>sym</mi></mrow></msub><mo>(</mo><mi>\u03c1</mi><mo>)</mo></math>) effects by learning the mapping between the symmetry energy and the two-dimensional (transverse momentum and rapidity) distributions of protons and neutrons in heavy-ion collisions. Supervised training is performed with labeled data-set from the ultrarelativistic quantum molecular dynamics (UrQMD) model simulation. It is found that, by using proton spectra on event-by-event basis as input, the accuracy for classifying the soft and stiff <math><msub><mrow><mi>E</mi></mrow><mrow><mi>sym</mi></mrow></msub><mo>(</mo><mi>\u03c1</mi><mo>)</mo></math> is about 60% due to large event-by-event fluctuations, while by setting event-summed proton spectra as input, the classification accuracy increases to 98%. The accuracies for 5-label (5 different <math><msub><mrow><mi>E</mi></mrow><mrow><mi>sym</mi></mrow></msub><mo>(</mo><mi>\u03c1</mi><mo>)</mo></math>) classification task are about 58% and 72% by using proton and neutron spectra, respectively. For the regression task, the mean absolute errors (MAE) which measure the average magnitude of the absolute differences between the predicted and actual L (the slope parameter of <math><msub><mrow><mi>E</mi></mrow><mrow><mi>sym</mi></mrow></msub><mo>(</mo><mi>\u03c1</mi><mo>)</mo></math>) are about 20.4 and 14.8 MeV by using proton and neutron spectra, respectively. Fingerprints of the density-dependent nuclear symmetry energy on the transverse momentum and rapidity distributions of protons and neutrons can be identified by convolutional neural network algorithm."
    }
  ], 
  "imprints": [
    {
      "date": "2021-10-26", 
      "publisher": "Elsevier"
    }
  ], 
  "acquisition_source": {
    "date": "2021-10-26T06:32:58.924452", 
    "source": "Elsevier", 
    "method": "Elsevier", 
    "submission_number": "25232ed0362611ecaa1b7aa32592193b"
  }
}
Published on:
26 October 2021
Publisher:
Elsevier
Published in:
Physics Letters B , Volume 822 C (2021)

Article ID: 136669
DOI:
https://doi.org/10.1016/j.physletb.2021.136669
Copyrights:
The Author(s)
Licence:
CC-BY-3.0

Fulltext files: