Muonic Hydrogen and the Proton Radius Puzzle

Pohl, Randolf; Gilman, R.; Miller, Gerald A.; Pachucki, Krzysztof

doi:10.1146/annurev-nucl-102212-170627

Cited by 362 publications

(517 citation statements)

References 169 publications

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“…A closely related issue that also depends on the magnitude of TPE corrections is the proton radius puzzle. We will only briefly sketch the problem here and refer to [1,643,[671][672][673][674] for detailed reviews. The basic outline is the same as in Fig.…”

Section: Overview Of Two-photon Physicsmentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

418

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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Section: Overview Of Two-photon Physicsmentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

418

530

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“…In what follows we specialize for simplicity to parity-preserving interactions and spinless compact central objects, and so strictly speaking the interactions we find suffice in themselves to describe finite-size effects in the He + ion or muonic states in even-even nuclei [24,[26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45]. The effects we find also apply to nuclei with spin (such as hydrogen) once the effective theory of the first-quantized source is supplemented by the extra interactions that a nuclear spin allows.…”

Section: Jhep09(2017)007mentioning

confidence: 99%

“…A fairly obvious use for contact interactions in the point-particle action is to parametrize the effects of any hypothetical new forces acting between nuclei and electrons or muons, and in particular forces that differ in strength between these two (since these can be captured through species-dependent values for c s and c v , unlike for r p ). Indeed the observation that the existence of such short-range interactions could, in principle, explain the proton radius puzzle [38][39][40] has led to efforts to better understand their size [53] and to the proposal of exotic interactions of this type [62][63][64][65].…”

Section: Jhep09(2017)007mentioning

confidence: 99%

Point-particle effective field theory III: relativistic fermions and the Dirac equation

Burgess¹,

Hayman²,

Rummel³

et al. 2017

J. High Energ. Phys.

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We formulate point-particle effective field theory (PPEFT) for relativistic spinhalf fermions interacting with a massive, charged finite-sized source using a first-quantized effective field theory for the heavy compact object and a second-quantized language for the lighter fermion with which it interacts. This description shows how to determine the near-source boundary condition for the Dirac field in terms of the relevant physical properties of the source, and reduces to the standard choices in the limit of a point source. Using a first-quantized effective description is appropriate when the compact object is sufficiently heavy, and is simpler than (though equivalent to) the effective theory that treats the compact source in a second-quantized way. As an application we use the PPEFT to parameterize the leading energy shift for the bound energy levels due to finite-sized source effects in a model-independent way, allowing these effects to be fit in precision measurements. Besides capturing finite-source-size effects, the PPEFT treatment also efficiently captures how other short-distance source interactions can shift bound-state energy levels, such as due to vacuum polarization (through the Uehling potential) or strong interactions for Coulomb bound states of hadrons, or any hypothetical new short-range forces sourced by nuclei.

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“…This example illustrates the phenomenological utility of the scale dependent, effective particle picture in QFT. The RGPEP can be applied to QED in description of hydrogen and muonic hydrogen atoms [15] for the purpose of explanation of the difference between the proton radii extracted from data for level splittings in these atoms [16]. This is a computationally ambitious goal.…”

Section: Early Examples Of Rgpep Insight In Phenomenology and Theorymentioning

confidence: 99%

“…Therefore, it needs to be evaluated numerically. It turns out that it is capable of producing a leptonmass correction in the extraction of proton radius from atomic levels, of the same magnitude [15] as the variation encountered in the proton radius puzzle [16] when the effective nature of particles appearing in the Schrödinger equation according the RGPEP is not accounted for.…”

Section: Early Examples Of Rgpep Insight In Phenomenology and Theorymentioning

confidence: 99%

Untitled

Głazek¹,

Trawiński²

2018

Light Cone 2016

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The concept of effective particles is introduced in the Minkowski space-time Hamiltonians in quantum field theory using a new kind of the relativistic renormalization group procedure that does not integrate out high-energy modes but instead integrates out the large changes of invariant mass. The new procedure is explained using examples of known interactions. Some applications in phenomenology, including processes measurable in colliders, are briefly presented.

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Muonic Hydrogen and the Proton Radius Puzzle

Cited by 362 publications

References 169 publications

Baryons as relativistic three-quark bound states

Baryons as relativistic three-quark bound states

Point-particle effective field theory III: relativistic fermions and the Dirac equation

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