scholarly journals The proton size puzzle: experiment vs theory.

2018 ◽  
Vol 191 ◽  
pp. 04001 ◽  
Author(s):  
A. E. Dorokhov ◽  
A. P. Martynenko ◽  
F. A. Martynenko ◽  
A. E. Radzhabov
Keyword(s):  
Charge Radius ◽  
Axial Vector ◽  
Muonic Hydrogen ◽  
Current Status ◽  
Interaction Operator ◽  
Two Photon ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Points Of View ◽  
Precise Experimental Data

Current status of the proton size puzzle from experimental and theoretical points of view is briefly discussed. The interest to these studies is primarily related to experiments conducted by the CREMA collaboration (Charge Radius Experi- ments with Muonic Atoms) with muonic hydrogen and deuterium by methods of laser spectroscopy. As a result a more accurate value of the proton charge radius was found to be rp = 0:84184(67) fm, which is different from the value recommended by CODATA for 7σ. In the second part we discuss recent calculations of the contribution of light pseudoscalar (PS) and axial-vector (AV) mesons to the interaction operator of a muon and a proton in muonic hydrogen atom, with the coupling of mesons to the muon being via two-photon intermediate state. Numerical estimates of the contributions to the hyperfine structure of the spectrum of the S and P levels are presented. It is shown that such contribution to the hyperfine splitting in muonic hydrogen is rather important for a comparison with precise experimental data.

scholarly journals Effects of light-by-light scattering in the Lamb shift and hyperfine structure of muonic hydrogen

2019 ◽  
Vol 222 ◽  
pp. 03010 ◽  
Author(s):  
A. E. Dorokhov ◽  
A. P. Martynenko ◽  
F. A. Martynenko ◽  
A. E. Radzhabov
Keyword(s):  
Experimental Data ◽  
Form Factor ◽  
Lamb Shift ◽  
Axial Vector ◽  
Muonic Hydrogen ◽  
Meson Exchange ◽  
Interaction Operator ◽  
Two Photon ◽  
Meson Coupling ◽  
Precise Experimental Data

We calculate the meson exchange contribution to the interaction operator of muon and proton, which is determined by the meson coupling with two photon state. For the construction of transition form factor Meson → γγ we use the existing parametrizations based on experimental data including the monopole parametrization over photon four-momenta. For an estimate of the form factor value atzero photon four-momenta squared we use experimental data on the decay width ΓMeson→γγ. It is shown that scalar, pseudoscalar, axial vector and tensor mesons exchanges give significant contribution to the Lamb shift (LS) and hyperfine splitting (HFS) in muonic hydrogen which should be taken into account for a comparison with precise experimental data.

scholarly journals Two-photon frequency comb spectroscopy of atomic hydrogen

Science ◽  
2020 ◽  
Vol 370 (6520) ◽  
pp. 1061-1066 ◽  
Author(s):  
Alexey Grinin ◽  
Arthur Matveev ◽  
Dylan C. Yost ◽  
Lothar Maisenbacher ◽  
Vitaly Wirthl ◽  
...  
Keyword(s):  
Quantum Electrodynamics ◽  
Atomic Hydrogen ◽  
Frequency Comb ◽  
Muonic Hydrogen ◽  
Significant Discrepancy ◽  
Two Photon ◽  
Proton Radius ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Proton Radius Puzzle

We have performed two-photon ultraviolet direct frequency comb spectroscopy on the 1S-3S transition in atomic hydrogen to illuminate the so-called proton radius puzzle and to demonstrate the potential of this method. The proton radius puzzle is a significant discrepancy between data obtained with muonic hydrogen and regular atomic hydrogen that could not be explained within the framework of quantum electrodynamics. By combining our result [f1S-3S = 2,922,743,278,665.79(72) kilohertz] with a previous measurement of the 1S-2S transition frequency, we obtained new values for the Rydberg constant [R∞ = 10,973,731.568226(38) per meter] and the proton charge radius [rp = 0.8482(38) femtometers]. This result favors the muonic value over the world-average data as presented by the most recent published CODATA 2014 adjustment.

scholarly journals Addendum to "Quantum Gravity and the Holographic Mass" in view of the 2013 Muonic Proton Charge Radius Measurement

2019 ◽  
Author(s):  
Nassim Haramein
Keyword(s):  
Standard Deviation ◽  
Charge Radius ◽  
Rest Mass ◽  
Muonic Hydrogen ◽  
Proton Accelerator ◽  
Proton Charge ◽  
Proton Mass ◽  
Proton Charge Radius ◽  
Holographic Approach ◽  
Paul Scherrer

We consider the latest results of the measurement of the charge radius of the proton utilizing laser spectroscopy of muonic hydrogen published in Science on January 25, 2013 by an international team lead by Aldo Antognini and carried out at the Paul Scherrer Institute Proton Accelerator. Given the new charge radius measurement, we compute the proton mass utilizing our generalized holographic approach and find that our result is now within 0.00072x10e-24 g of the 2010-CODATA value of the proton rest mass. Our predicted charge radius is now within 0.00036x10e-13 cm and remains within one standard deviation of the new measurement.

The muonic hydrogen Lamb-shift experiment

2005 ◽  
Vol 83 (4) ◽  
pp. 339-349 ◽  
Author(s):  
R Pohl ◽  
A Antognini ◽  
F D Amaro ◽  
F Biraben ◽  
J MR Cardoso ◽  
...  
Keyword(s):  
Charge Radius ◽  
Quantum Electrodynamics ◽  
Lamb Shift ◽  
Laser System ◽  
Bound State ◽  
Muonic Hydrogen ◽  
X Rays ◽  
Large Area ◽  
Proton Charge ◽  
Proton Charge Radius

The charge radius of the proton, the simplest nucleus, is known from electron-scattering experiments only with a surprisingly low precision of about 2%. The poor knowledge of the proton charge radius restricts tests of bound-state quantum electrodynamics (QED) to the precision level of about 6 × 10–6, although the experimental data themselves (1S Lamb shift in hydrogen) have reached a precision of 2 × 10–6. The determination of the proton charge radius with an accuracy of 10–3 is the main goal of our experiment, opening a way to check bound-state QED predictions to a level of 10–7. The principle is to measure the 2S–2P energy difference in muonic hydrogen (µ–p) by infrared laser spectroscopy. The first data were taken in the second half of 2003. Muons from our unique very-low-energy muon beam are stopped at a rate of ~100 s–1 in 0.6 mbar H2 gas where the lifetime of the formed µp(2S) atoms is about 1.3 µs. An incoming muon triggers a pulsed multistage laser system that delivers ~0.2 mJ at λ ≈ 6 µm. Following the laser excitation µp(2S) → µp(2P) we observe the 1.9 keV X-rays from 2P–1S transitions using large area avalanche photodiodes. The resonance frequency, and, hence, the Lamb shift and the proton radius, is determined by measuring the intensity of these X-rays as a function of the laser wavelength. A broad range of laser frequencies was scanned in 2003 and the analysis is currently under way. PACS Nos.: 36.10.Dr, 14.20.Dh, 42.62.Fi

scholarly journals Status of the muonic hydrogen Lamb-shift experiment

2007 ◽  
Vol 85 (5) ◽  
pp. 469-478 ◽  
Author(s):  
T Nebel ◽  
F D Amaro ◽  
A Antognini ◽  
F Biraben ◽  
J MR Cardoso ◽  
...  
Keyword(s):  
Charge Radius ◽  
Lamb Shift ◽  
Bound State ◽  
Muonic Hydrogen ◽  
X Ray ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Experimental Apparatus ◽  
Shift Experiment ◽  
Bound State Qed

The Lamb-shift experiment in muonic hydrogen (μ– p) aims to measure the energy difference between the [Formula: see text] atomic levels to a precision of 30 ppm. This would allow the r.m.s. proton charge radius rp to be deduced to a precision of 10–3 and open a way to check bound-state quantum electrodynamics (QED) to a level of 10–7. The poor knowledge of the proton charge radius restricts tests of bound-state QED to the precision level of about 6 × 10–6, although the experimental data themselves (Lamb-shift in hydrogen) have reached a precision of  × 10–6. Values for rp not depending on bound-state QED results from electron scattering experiments have a surprisingly large uncertainty of 2%. In our Lamb-shift experiment, low-energy negative muons are stopped in low-density hydrogen gas, where, following the μ– atomic capture and cascade, 1% of the muonic hydrogen atoms form the metastable 2S state with a lifetime of about 1 μs. A laser pulse at λ ≈ 6 μm is used to drive the 2S → 2P transition. Following the laser excitation, we observe the 1.9 keV X-ray being emitted during the subsequent de-excitation to the 1S state using large-area avalanche photodiodes. The resonance frequency and, hence, the Lamb shift and the proton charge radius are determined by measuring the intensity of the X-ray fluorescence as a function of the laser wavelength. The results of the run in December 2003 were negative but, nevertheless, promising. One by-product of the 2003 run was the first observation of the short-lived 2S component in muonic hydrogen. Currently, improvements in the laser-system, the experimental apparatus, and the data acquisition are being implemented. PACS Nos.: 36.10.Dr, 14.20.Dh, 42.62.Fi

The Lamb shift in muonic hydrogenThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.

2011 ◽  
Vol 89 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Randolf Pohl ◽  
Aldo Antognini ◽  
François Nez ◽  
Fernando D. Amaro ◽  
François Biraben ◽  
...  
Keyword(s):  
Charge Radius ◽  
Lamb Shift ◽  
Finite Size ◽  
Muonic Hydrogen ◽  
Energy Splitting ◽  
Atomic Systems ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Rydberg Constant ◽  
Better Than

The long quest for a measurement of the Lamb shift in muonic hydrogen is over. Last year we measured the 2S 1/2F=1 –2P 3/2F=2 energy splitting (Pohl et al., Nature, 466, 213 (2010)) in μp with an experimental accuracy of 15 ppm, twice better than our proposed goal. Using current QED calculations of the fine, hyperfine, QED, and finite size contributions, we obtain a root-mean-square proton charge radius of rp = 0.841 84 (67) fm. This value is 10 times more precise, but 5 standard deviations smaller, than the 2006 CODATA value of rp. The origin of this discrepancy is not known. Our measurement, together with precise measurements of the 1S–2S transition in regular hydrogen and deuterium, gives improved values of the Rydberg constant, R∞ = 10 973 731.568 160 (16) m–1 and the rms charge radius of the deuteron rd = 2.128 09 (31) fm.

scholarly journals A small proton charge radius from an electron–proton scattering experiment

Nature ◽  
2019 ◽  
Vol 575 (7781) ◽  
pp. 147-150 ◽  
Author(s):  
W. Xiong ◽  
A. Gasparian ◽  
H. Gao ◽  
D. Dutta ◽  
M. Khandaker ◽  
...  
Keyword(s):  
Charge Radius ◽  
Proton Scattering ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Scattering Experiment

Solution to the proton radius puzzle

2014 ◽  
Vol 23 (12) ◽  
pp. 1450090 ◽  
Author(s):  
D. Robson
Keyword(s):  
Form Factor ◽  
Electron Scattering ◽  
Charge Radius ◽  
Rest Frame ◽  
Muonic Hydrogen ◽  
Electric Form Factor ◽  
Scattering Data ◽  
Proton Radius ◽  
Proton Charge Radius ◽  
Proton Radius Puzzle

The relationship between the static electric form factor for the proton in the rest frame and the Sachs electric form factor in the Breit momentum frame is used to provide a value for the difference in the mean squared charge radius of the proton evaluated in the two frames. Associating the muonic–hydrogen data analysis for the proton charge radius of 0.84087 fm with the rest frame and associating the electron scattering data with the Breit frame yields a prediction of 0.87944 fm for the proton radius in the relativistic frame. The most recent value deduced via electron scattering from the proton is 0.877(6) fm so that the frame dependence used here yields a plausible solution to the proton radius puzzle.

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