Pion and kaon elastic form factors in a refined light-front model

Silva, Edson O. da; Melo, J. P. B. C. de; El-Bennich, Bruno; Filho, Victo S.

doi:10.1103/physrevc.86.038202

Cited by 37 publications

(25 citation statements)

References 56 publications

(53 reference statements)

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“…8 Note that the spin effect is ignored in LFHQCD (cf. [41][42][43][44][45]). So ρ and π share the same spatial LFWF hence form factors in the Drell-Yan frame Here η s is the ground-state pseudoscalar ss meson, which does not have any correspondence in Nature.…”

Section: Discussionmentioning

confidence: 99%

Frame dependence of form factors in light-front dynamics

Li¹,

Maris²,

Vary³

2018

Phys. Rev. D

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In light-front dynamics, form factors are traditionally computed with the "good current" J þ within the Drell-Yan frame q þ ¼ 0. Due to truncations imposed in practical calculations, the from factor may acquire frame dependence, which is often neglected. In this work, we explore the form factors in more general frames, preserving the boost covariance. We find the frame dependence of the elastic form factors for mesons is small in basis light-front holography and related models with two-body Fock space truncation. We suggest to use the difference between form factor results from Drell-Yan frame and the "longitudinal frame" as a metric for the violation of the Lorentz symmetry due to Fock space truncation.

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Section: Discussionmentioning

confidence: 99%

Frame dependence of form factors in light-front dynamics

Li¹,

Maris²,

Vary³

2018

Phys. Rev. D

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“…The internal structure of kaons can be explored by the electromagnetic form factors (EMFFs), which reflect the underlying quark-gluon dynamics [15,16]. Many attempts have been made to understand the internal structure of kaons using various approaches, e.g., the Dyson-Schwinger equation (DSE), Nambu-Jona-Lasinio (NJL) model, chiral perturbation theory (ChPT), and instanton vacuum-based models [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Experimentally, K-meson EMFFs are poorly known, except for the K − in the low Q 2 region (Q 2 < 0.2 GeV 2 ) [30], where Q 2 = −q 2 and q is the four-momentum transfer.…”

Section: Introductionmentioning

confidence: 99%

Electroweak properties of pions in a nuclear medium

Hutauruk

Tsushima

2019

Phys. Rev. C

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Kaon electroweak properties in symmetric nuclear matter are studied in the Nambu-Jona-Lasinio model using the proper-time regularization. The valence quark properties in symmetric nuclear matter are calculated in the quark-meson coupling model, and they are used as inputs for studying the in-medium kaon properties in the NJL model. We evaluate the kaon decay constant, kaon-quark coupling constant, and K + electromagnetic form factor by two different approaches. Namely, by two different ways of calculating the in-medium constituent quark masses of the light quarks. We predict that, in both approaches, the kaon decay constant and kaon-quark coupling constant decrease as nuclear density increases, while the K + charge radius increases by 20-25% at normal nuclear density. * parada.hutauruk@apctp.org † kazuo.tsushima@gmail.com following reasons; (i) the constituent quark masses in vacuum are the input parameters in Ref.[32], but it is preferable to calculate them dynamically, (ii) the vacuum in the light-front approach is generally believed to be "trivial", and there is no clearly defined quark chiral condensates in the light-front approach. Thus, the model does not have the dynamical chiral symmetry breaking mechanism nor does the model have direct connection with the emergence of (pseudo-)Goldstone bosons such as kaons, and (iii) the in-medium kaon decay constant as well as the kaon-quark coupling constant are assumed to be density-independent. The purpose of the present work is to improve further the work of Ref. [32]. We extend the approach used for studying the pion properties in symmetric nuclear matter in Ref. [33], and study the in-medium kaon properties using the Nambu-Jona-Lasinio (NJL) model [34,35], supplemented by the QMC model inputs. The NJL model is a powerful chiral effective quark theory of low-energy QCD. Importantly, the model describes the dynamical chiral symmetry breaking, the origin of the pseudoscalar Goldstone bosons such as pions and kaons. Furthermore, the model satisfies the chiral limit as QCD dictates. Thus, the NJL model, which has several improved aspects as addressed above, is suitable to study the in-medium kaon properties.The experimental evidences, such as the EMC effect [36,37] and the observed modifications of bound proton EMFFs at JLab [38], suggest that the internal structure of hadrons would be modified in a nuclear medium. The phenomena of inmedium modifications of hadron properties [39][40][41][42][43][44][45][46][47][48][49][50] are tightly connected with partial restoration of chiral symmetry [51][52][53][54]. The order parameters of chiral symmetry in QCD are the lightquark chiral condensates, and their changes are expected to be one of the most important driving forces for the change of hadron properties in a nuclear medium.Spontaneous breaking of chiral symmetry generates the nonet of massless pseudoscalar Goldstone bosons. But the explicit breaking of U(1) axial symmetry selectively shifts up the η 0 -singlet mass, leaving the SU(3) flavor octet of pions, K-mesons, and...

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“…There have been numerous studies of hadron PDFs and form factors within quark models of various degrees of sophistication and success, for example, see Refs. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], respectively.…”

Section: Introductionmentioning

confidence: 99%

Flavor dependence of the pion and kaon form factors and parton distribution functions

2016

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The separate quark flavour contributions to the pion and kaon valence quark distribution functions are studied, along with the corresponding electromagnetic form factors in the space-like region. The calculations are made using the solution of the Bethe-Salpeter equation for the model of Nambu and Jona-Lasinio with proper-time regularization. Both the pion and kaon form factors and the valence quark distribution functions reproduce many features of the available empirical data. The larger mass of the strange quark naturally explains the empirical fact that the ratio u K + (x)/u π + (x) drops below unity at large x, with a value of approximately M 2 u /M 2 s as x → 1. With regard to the elastic form factors we report a large flavour dependence, with the u-quark contribution to the kaon form factor being an order of magnitude smaller than that of the s-quark at large Q 2 , which may be a sensitive measure of confinement effects in QCD. Surprisingly though, the total K + and π + form factors differ by only 10%. In general we find that flavour breaking effects are typically around 20%.

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Pion and kaon elastic form factors in a refined light-front model

Cited by 37 publications

References 56 publications

Frame dependence of form factors in light-front dynamics

Frame dependence of form factors in light-front dynamics

Electroweak properties of pions in a nuclear medium

Flavor dependence of the pion and kaon form factors and parton distribution functions

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