Nucleon form factors and the pion-nucleon sigma term

Rajan Gupta; Tanmoy Bhattacharya; Vincenzo Cirigliano; Martin Hoferichter; Yong Chull Jang; Balint Joo; Emanuele Mereghetti; Santanu Mondal; Sungwoo Park; Frank Winter; Boram Yoon

Nucleon form factors and the pion-nucleon sigma term

Rajan Gupta, Tanmoy Bhattacharya, Vincenzo Cirigliano, Martin Hoferichter, Yong Chull Jang, Balint Joo, Emanuele Mereghetti, Santanu Mondal, Sungwoo Park, Frank Winter, Boram Yoon

Advanced Computing for Nuclear, Particle

Research output: Contribution to journal › Conference article › peer-review

Abstract

This talk summarizes the progress made since Lattice 2021 in understanding and controlling the contributions of towers of multihadron excited states with mass gaps starting lower than of radial excitations, and in increasing our confidence in the extraction of ground state nucleon matrix elements. The most clear evidence for multihadron excited state contributions (ESC) is in axial/pseudoscalar form factors that are required to satisfy the PCAC relation between them. The talk examines the broader question-which and how many of the theoretically allowed positive parity states N(p)π(- p), N(0)π(0)π(0), N(p)π(0), N(0)π(p), ... make significant contributions to a given nucleon matrix element? New data for the axial, electric and magnetic form factors are presented. They continue to show trends observed in Ref. [1]. The N²LO χPT analysis of the ESC to the pion-nucleon sigma term, σ_πN, has been extended to include the Δ as an explicit degree of freedom [2]. The conclusion reached in Ref. [3] that Nπ and Nππ states each contribute about 10 MeV to σ_πN, and the consistency between the lattice result with Nπ state included and the phenomenological estimate is not changed by this improvement.

Original language	English
Article number	427
Journal	Proceedings of Science
Volume	430
State	Published - Apr 6 2023
Event	39th International Symposium on Lattice Field Theory, LATTICE 2022 - Bonn, Germany Duration: Aug 8 2022 → Aug 13 2022

Funding

The calculations presented are based on two sets of ensembles: the 2 + 1 + 1-flavor HISQ ensembles generated by the MILC collaboration and the 2 + 1-flavor Wilson-clover ensembles generated by the JLAB/W&M/LANL/MIT collaborations. The calculations used the Chroma software suite [25]. We gratefully acknowledge computing resources provided by NERSC; OLCF at Oak Ridge through ALCC awards NPH110 and LGT107, and INCITE awards PHY138 and HEP133; USQCD clusters; and LANL Institutional Computing. Support for this work was provided by the U.S. DOE Office of Science HEP and NP, and the SNSF. T. Bhattacharya and R. Gupta were partly supported by the U.S. DOE, Office of Science, HEP under Contract No. DE-AC52-06NA25396. T. Bhattacharya, R. Gupta, S. Mondal, S. Park, and B. Yoon were partly supported by the LANL LDRD program, and S. Park by the Center for Nonlinear Studies.

Cite this

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title = "Nucleon form factors and the pion-nucleon sigma term",

abstract = "This talk summarizes the progress made since Lattice 2021 in understanding and controlling the contributions of towers of multihadron excited states with mass gaps starting lower than of radial excitations, and in increasing our confidence in the extraction of ground state nucleon matrix elements. The most clear evidence for multihadron excited state contributions (ESC) is in axial/pseudoscalar form factors that are required to satisfy the PCAC relation between them. The talk examines the broader question-which and how many of the theoretically allowed positive parity states N(p)π(- p), N(0)π(0)π(0), N(p)π(0), N(0)π(p), ... make significant contributions to a given nucleon matrix element? New data for the axial, electric and magnetic form factors are presented. They continue to show trends observed in Ref. [1]. The N2LO χPT analysis of the ESC to the pion-nucleon sigma term, σπN, has been extended to include the Δ as an explicit degree of freedom [2]. The conclusion reached in Ref. [3] that Nπ and Nππ states each contribute about 10 MeV to σπN, and the consistency between the lattice result with Nπ state included and the phenomenological estimate is not changed by this improvement.",

author = "Rajan Gupta and Tanmoy Bhattacharya and Vincenzo Cirigliano and Martin Hoferichter and Jang, {Yong Chull} and Balint Joo and Emanuele Mereghetti and Santanu Mondal and Sungwoo Park and Frank Winter and Boram Yoon",

note = "Publisher Copyright: {\textcopyright} Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).; 39th International Symposium on Lattice Field Theory, LATTICE 2022 ; Conference date: 08-08-2022 Through 13-08-2022",

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T1 - Nucleon form factors and the pion-nucleon sigma term

AU - Gupta, Rajan

AU - Bhattacharya, Tanmoy

AU - Cirigliano, Vincenzo

AU - Hoferichter, Martin

AU - Jang, Yong Chull

AU - Joo, Balint

AU - Mereghetti, Emanuele

AU - Mondal, Santanu

AU - Park, Sungwoo

AU - Winter, Frank

AU - Yoon, Boram

N1 - Publisher Copyright: © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).

PY - 2023/4/6

Y1 - 2023/4/6

N2 - This talk summarizes the progress made since Lattice 2021 in understanding and controlling the contributions of towers of multihadron excited states with mass gaps starting lower than of radial excitations, and in increasing our confidence in the extraction of ground state nucleon matrix elements. The most clear evidence for multihadron excited state contributions (ESC) is in axial/pseudoscalar form factors that are required to satisfy the PCAC relation between them. The talk examines the broader question-which and how many of the theoretically allowed positive parity states N(p)π(- p), N(0)π(0)π(0), N(p)π(0), N(0)π(p), ... make significant contributions to a given nucleon matrix element? New data for the axial, electric and magnetic form factors are presented. They continue to show trends observed in Ref. [1]. The N2LO χPT analysis of the ESC to the pion-nucleon sigma term, σπN, has been extended to include the Δ as an explicit degree of freedom [2]. The conclusion reached in Ref. [3] that Nπ and Nππ states each contribute about 10 MeV to σπN, and the consistency between the lattice result with Nπ state included and the phenomenological estimate is not changed by this improvement.

AB - This talk summarizes the progress made since Lattice 2021 in understanding and controlling the contributions of towers of multihadron excited states with mass gaps starting lower than of radial excitations, and in increasing our confidence in the extraction of ground state nucleon matrix elements. The most clear evidence for multihadron excited state contributions (ESC) is in axial/pseudoscalar form factors that are required to satisfy the PCAC relation between them. The talk examines the broader question-which and how many of the theoretically allowed positive parity states N(p)π(- p), N(0)π(0)π(0), N(p)π(0), N(0)π(p), ... make significant contributions to a given nucleon matrix element? New data for the axial, electric and magnetic form factors are presented. They continue to show trends observed in Ref. [1]. The N2LO χPT analysis of the ESC to the pion-nucleon sigma term, σπN, has been extended to include the Δ as an explicit degree of freedom [2]. The conclusion reached in Ref. [3] that Nπ and Nππ states each contribute about 10 MeV to σπN, and the consistency between the lattice result with Nπ state included and the phenomenological estimate is not changed by this improvement.

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Y2 - 8 August 2022 through 13 August 2022

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Nucleon form factors and the pion-nucleon sigma term

Abstract

Funding

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