Nucleon electromagnetic form factors in the timelike region

Denig, A.; Salmè, G.

doi:10.1016/j.ppnp.2012.09.005

Cited by 95 publications

(91 citation statements)

References 142 publications

(352 reference statements)

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“…point-like case [9] can be readily found in those publications where experiments for e + e − ↔pp were reported [11,12,52,53]. The effective form factor for the point-like case would be simply a straight line in Fig.…”

Section: Resultsmentioning

confidence: 88%

“…There is a well-known systematical difference between the e + e − →pp andpp → e + e − cross section data [9], where the latter are smaller by a factor of about 1.47. But once we take that into account by a proper renormalization of our results (using the same renormalization factor for all consideredNN interactions) we reproduce the PS170 measurement rather nicely as can be seen in Fig.…”

Section: Resultsmentioning

confidence: 99%

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The electromagnetic form factors of the proton in the timelike region

2014

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The reactionspp → e + e − and e + e − →pp are analyzed in the near-threshold region. Specific emphasis is put on the role played by the interaction in the initial-or final antinucleon-nucleon (NN) state which is taken into account rigorously. For that purpose a recently publishedNN potential derived within chiral effective field theory and fitted to results of a new partial-wave analysis ofpp scattering data is employed. Our results provide strong support for the conjecture that the pronounced energy dependence of the e + e − ↔pp cross section, seen in pertinent experiments, is primarily due to thepp interaction. Predictions for the proton electromagnetic form factors G E and G M in the timelike region, close to theNN threshold, and for spin-dependent observables are presented. The steep rise of the effective form factor for energies close to thepp threshold is explained solely in terms of thepp interaction. The corresponding experimental information is quantitatively described by our calculation.

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Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 99%

The electromagnetic form factors of the proton in the timelike region

2014

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“…Naturally, our own bias is towards the Dyson-Schwinger/Bethe-Salpeter approach and therefore we will mainly concentrate on pointing out its connections with other methods and the inherent similarities and differences. We apologize to those colleagues whose work is not mentioned here; for more comprehensive discussions we refer to the existing reviews focusing on nucleon spacelike electromagnetic form factors [440][441][442][443][444][445][446], axial form factors [447,448], transition form factors [11][12][13][14], and timelike form factors [445,449].…”

Section: Methodological Overviewmentioning

confidence: 99%

“…An important aspect of form factors is their timelike structure at negative Q 2 which is governed by particle production off the photon; see [445,449] for reviews. Form factors are analytic functions in the physical sheet apart from a branch cut starting at the two-pion threshold Q 2 < −4m 2 π and extending to minus infinity.…”

Section: Methodological Overviewmentioning

confidence: 99%

“…Dispersion theory makes it clear that the timelike and spacelike properties are intrinsically related, and in this respect it is curious that many quark models capable of providing a good spacelike description do not have such mechanisms implemented at all (with exceptions discussed further below). In any case, the experimental situation may change in the future with new precision data on timelike nucleon form factors expected from Novosibirsk, BESIII/Beijing and PANDA/FAIR [449], and timelike reactions are also promising tools to extract the properties of nucleon resonances [485][486][487]. …”

Section: Methodological Overviewmentioning

confidence: 99%

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Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

438

530

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We review the spectrum and electromagnetic properties of baryons described as relativistic three-quark bound states within QCD. The composite nature of baryons results in a rich excitation spectrum, whilst leading to highly non-trivial structural properties explored by the coupling to external (electromagnetic and other) currents. Both present many unsolved problems despite decades of experimental and theoretical research. We discuss the progress in these fields from a theoretical perspective, focusing on nonperturbative QCD as encoded in the functional approach via Dyson-Schwinger and Bethe-Salpeter equations. We give a systematic overview as to how results are obtained in this framework and explain technical connections to lattice QCD. We also discuss the mutual relations to the quark model, which still serves as a reference to distinguish 'expected' from 'unexpected' physics. We confront recent results on the spectrum of non-strange and strange baryons, their form factors and the issues of two-photon processes and Compton scattering determined in the DysonSchwinger framework with those of lattice QCD and the available experimental data. The general aim is to identify the underlying physical mechanisms behind the plethora of observable phenomena in terms of the underlying quark and gluon degrees of freedom.

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Top-quark partial compositeness beyond the effective field theory paradigm

Franzosi

Tonero

2020

J. High Energ. Phys.

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In theories of Partial Compositeness the top quark is a mixture of a composite and an elementary state, and as a consequence its interactions with gauge bosons are expected to deviate from those of a point-like object. At sufficiently large energies, such deviations cannot be parametrized by the leading effective field theory operators and form factors (i.e. energy dependent interactions) must be introduced. In this work, we argue that such effects might appear at relatively low energies with interesting phenomenological consequences. In analogy to the proton electromagnetic interactions, we devise a simplified phenomenological model that parametrizes the top-quark interactions with gluons in terms of two form factors. We study the implications of these interactions in top-quark and heavy top-partner pair production at a hadron collider.

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Nucleon electromagnetic form factors in the timelike region

Cited by 95 publications

References 142 publications

The electromagnetic form factors of the proton in the timelike region

The electromagnetic form factors of the proton in the timelike region

Baryons as relativistic three-quark bound states

Top-quark partial compositeness beyond the effective field theory paradigm

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