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Nucleon form factors in dispersively improved chiral effective field theory: Scalar form factor

Journal Article · · Physical Review C
 [1];  [1]
  1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

We propose a method for calculating the nucleon form factors (FFs) of $$G$$-parity-even operators by combining Chiral Effective Field Theory ($$\chi$$EFT) and dispersion analysis. The FFs are expressed as dispersive integrals over the two-pion cut at $$t > 4 M_\pi^2$$. The spectral functions are obtained from the elastic unitarity condition and expressed as products of the complex $$\pi\pi \rightarrow N\bar N$$ partial-wave amplitudes and the timelike pion FF. $$\chi$$EFT is used to calculate the ratio of the partial-wave amplitudes and the pion FF, which is real and free of $$\pi\pi$$ rescattering in the $$t$$-channel ($N/D$ method). The rescattering effects are then incorporated by multiplying with the squared modulus of the empirical pion FF. The procedure results in a marked improvement compared to conventional $$\chi$$EFT calculations of the spectral functions. We apply the method to the nucleon scalar FF and compute the scalar spectral function, the scalar radius, the $$t$$-dependent FF, and the Cheng-Dashen discrepancy. Higher-order chiral corrections are estimated through the $$\pi N$$ low-energy constants. Results are in excellent agreement with dispersion-theoretical calculations. We elaborate several other interesting aspects of our method. The results show proper scaling behavior in the large-$$N_c$$ limit of QCD because the $$\chi$$EFT includes $$N$$ and $$\Delta$$ intermediate states. The squared modulus of the timelike pion FF required by our method can be extracted from Lattice QCD calculations of vacuum correlation functions of the operator at large Euclidean distances. Our method can be applied to the nucleon FFs of other operators of interest, such as the isovector-vector current, the energy-momentum tensor, and twist-2 QCD operators (moments of generalized parton distributions).

Research Organization:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Grant/Contract Number:
AC05-06OR23177
OSTI ID:
1410288
Alternate ID(s):
OSTI ID: 1409461
Report Number(s):
JLAB-THY--17-2525; DOE/OR/--23177-4275; arXiv:1707.07682
Journal Information:
Physical Review C, Journal Name: Physical Review C Journal Issue: 5 Vol. 96; ISSN PRVCAN; ISSN 2469-9985
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

References (95)

Quantum Chromodynamics and Chiral Symmetry book January 2011
Chiral dynamics and peripheral transverse densities journal January 2014
Dispersive analysis of the scalar form factor of the nucleon journal June 2012
Light-front representation of chiral dynamics with Δ isobar and large-N c relations journal June 2016
Light-front representation of chiral dynamics in peripheral transverse densities journal July 2015
Baryon chiral perturbation theory in manifestly Lorentz invariant form journal July 1999
Chiral perturbation theory to one loop journal November 1984
Hadron properties from QCD sum rules journal October 1985
The Skyrme model journal September 1986
Remarks on Higgs-boson interactions with nucleons journal October 1978
Sigma-term update journal January 1991
Form factor of the σ-term journal January 1991
The role of the Δ isobar in chiral perturbation theory and hedgehog soliton models journal October 1992
The skyrmion-skyrmion interaction journal January 1985
A planar diagram theory for strong interactions journal April 1974
The ϱNN vertex in vector-dominance models journal September 1975
QCD and resonance physics. theoretical foundations journal February 1979
QCD and resonance physics. applications journal February 1979
Baryons in the expansion journal November 1979
Static properties of nucleons in the Skyrme model journal December 1983
Chiral perturbation theory: Expansions in the mass of the strange quark journal January 1985
Nucleons with chiral loops journal October 1988
The role of resonances in chiral perturbation theory journal July 1989
The g1 problem: Deep inelastic electron scattering and the spin of the proton journal June 1990
Chiral unitary approach to meson-meson and meson-baryon interactions and nuclear applications journal January 2000
Hard exclusive reactions and the structure of hadrons journal January 2001
Chiral dynamics in the presence of bound states: kaon–nucleon interactions revisited journal February 2001
Correspondence of consistent and inconsistent spin-3/2 couplings via the equivalence theorem journal March 2001
Generalized parton distributions and strong forces inside nucleons and nuclei journal February 2003
Systematic expansion for spin particles in baryon chiral perturbation theory journal March 1997
Chiral unitary meson–baryon dynamics in the presence of resonances: elastic pion–nucleon scattering journal June 2000
Low-energy analysis of the nucleon electromagnetic form factors journal January 2001
Nucleon electroweak form factors: Analysis of their spectral functions journal December 1996
Aspects of chiral pion-nucleon physics journal April 1997
Improved description of the -scattering phenomenology at low energies in covariant baryon chiral perturbation theory journal September 2013
Peripheral transverse densities of the baryon octet from chiral effective field theory and dispersion analysis journal August 2017
Scalar form factors of light mesons journal November 2004
Novel evaluation of the two-pion contribution to the nucleon isovector form factors journal February 2006
Scalar radius of the pion and zeros in the form factor journal July 2007
The strangeness content of the nucleon from effective field theory and phenomenology journal March 2014
Dispersive evaluation of the D-term form factor in deeply virtual Compton scattering journal December 2014
Chiral dynamics in the γ → p → p π 0 reaction journal July 2015
Reconciling threshold and subthreshold expansions for pion–nucleon scattering journal July 2017
Generalized parton distributions journal December 2003
Unraveling hadron structure with generalized parton distributions journal October 2005
Nucleon electromagnetic form factors journal October 2007
Progress in three-particle scattering from LQCD journal January 2017
Heavy baryon chiral perturbation theory with light deltas journal October 1998
Axial structure of the nucleon journal November 2001
Low energy analysis of π N →π N journal May 2001
Chiral effective theory of dark matter direct detection journal February 2017
Partial-Wave Dispersion Relations for the Process π + π → N + N ¯ journal March 1960
Effect of a Pion-Pion Scattering Resonance on Nucleon Structure. II journal March 1960
Theory of the Low-Energy Pion-Pion Interaction journal July 1960
Some General Relations between the Photoproduction and Scattering of π Mesons journal July 1954
Field theory of nucleon to higher-spin baryon transitions journal September 1999
Spectral functions of isoscalar-scalar and isovector-electromagnetic form factors of the nucleon at two-loop order journal August 2003
On-shell consistency of the Rarita-Schwinger field formulation journal August 2009
π N scattering in relativistic baryon chiral perturbation theory reexamined journal May 2011
Nucleon-nucleon interactions from dispersion relations: Elastic partial waves journal November 2011
Nucleon-nucleon interactions from dispersion relations: Coupled partial waves journal September 2012
Erratum: π N scattering in relativistic baryon chiral perturbation theory reexamined [Phys. Rev. C 83 , 055205 (2011)] journal May 2013
Moments of nucleon structure functions at next-to-leading order in baryon chiral perturbation theory journal November 2014
Naive quark model for an arbitrary number of colors journal July 1984
1 N c expansion for baryons journal May 1994
Erratum: 1 N c expansion for baryons journal March 1995
Spin-flavor structure of large N c baryons journal April 1995
Quantization of an interacting spin- 3 2 field and the Δ isobar journal September 1998
N / D description of two meson amplitudes and chiral symmetry journal September 1999
Renormalization of relativistic baryon chiral perturbation theory and power counting journal September 2003
Chiral dynamics and the growth of the nucleon’s gluonic transverse size at small x journal March 2004
Chiral dynamics and partonic structure at large transverse distances journal December 2009
Nucleon and Δ ( 1232 ) form factors at low momentum transfer and small pion masses journal February 2012
Chiral representation of the π N scattering amplitude and the pion-nucleon sigma term journal March 2012
Lepton flavor violation in the Higgs sector and the role of hadronic τ -lepton decays journal January 2014
Octet-baryon axial-vector charges and S U ( 3 ) -breaking effects in the semileptonic hyperon decays journal September 2014
Hyperon forward spin polarizability γ 0 in baryon chiral perturbation theory journal November 2015
Δ ( 1232 ) resonance in the γ → p → p π 0 reaction at threshold journal May 2016
Analysis strategies for general spin-independent WIMP-nucleus scattering journal September 2016
Leading SU(3)-Breaking Corrections to the Baryon Magnetic Moments in Chiral Perturbation Theory journal November 2008
Lattice QCD and the Timelike Pion Form Factor journal August 2011
High-Precision Determination of the Pion-Nucleon σ Term from Roy-Steiner Equations journal August 2015
Is SU ( 2 ) ⊗ SU ( 2 ) a Better Symmetry than SU(3)? journal March 1971
Chiral-Symmetry Breakdown in Large- N Chromodynamics journal July 1980
Gauge-Invariant Decomposition of Nucleon Spin journal January 1997
Chiral and large- N c limits of quantum chromodynamics and models of the baryon journal April 1996
On the $\pi\pi$ π π continuum in the nucleon form factors and the proton radius puzzle journal November 2016
The electromagnetic Sigma-to-Lambda hyperon transition form factors at low energies journal June 2017
Three-body unitarity with isobars revisited journal September 2017
Predictive powers of chiral perturbation theory in Compton scattering off protons journal November 2009
Chiral perturbation theory of muonic-hydrogen Lamb shift: polarizability contribution journal April 2014
Impact Parameter Space Interpretation for Generalized Parton Distributions journal January 2003
Chiral Dynamics in Nucleons and Nuclei journal June 1995
Transverse Charge Densities journal November 2010
LARGE- N c BARYONS journal December 1998

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