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.

A measurement of the atomic hydrogen Lamb shift and the proton charge radius

Science ◽  
2019 ◽  
Vol 365 (6457) ◽  
pp. 1007-1012 ◽  
Author(s):  
N. Bezginov ◽  
T. Valdez ◽  
M. Horbatsch ◽  
A. Marsman ◽  
A. C. Vutha ◽  
...  
Keyword(s):  
Direct Measurement ◽  
Charge Radius ◽  
Atomic Hydrogen ◽  
Lamb Shift ◽  
Shift Measurement ◽  
Proton Radius ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Proton Radius Puzzle

The surprising discrepancy between results from different methods for measuring the proton charge radius is referred to as the proton radius puzzle. In particular, measurements using electrons seem to lead to a different radius compared with those using muons. Here, a direct measurement of the n = 2 Lamb shift of atomic hydrogen is presented. Our measurement determines the proton radius to be rp = 0.833 femtometers, with an uncertainty of ±0.010 femtometers. This electron-based measurement of rp agrees with that obtained from the analogous muon-based Lamb shift measurement but is not consistent with the larger radius that was obtained from the averaging of previous electron-based measurements.

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.

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 The Rydberg constant and proton size from atomic hydrogen

Science ◽  
2017 ◽  
Vol 358 (6359) ◽  
pp. 79-85 ◽  
Author(s):  
Axel Beyer ◽  
Lothar Maisenbacher ◽  
Arthur Matveev ◽  
Randolf Pohl ◽  
Ksenia Khabarova ◽  
...  
Keyword(s):  
Atomic Hydrogen ◽  
Quantum Interference ◽  
Muonic Hydrogen ◽  
Mean Square ◽  
Charge Radii ◽  
The Core ◽  
Proton Radius ◽  
Rydberg Constant ◽  
Proton Radius Puzzle ◽  
Good Agreement

At the core of the “proton radius puzzle” is a four–standard deviation discrepancy between the proton root-mean-square charge radii (rp) determined from the regular hydrogen (H) and the muonic hydrogen (µp) atoms. Using a cryogenic beam of H atoms, we measured the 2S-4P transition frequency in H, yielding the values of the Rydberg constantR∞= 10973731.568076(96) per meterandrp= 0.8335(95) femtometer. Ourrpvalue is 3.3 combined standard deviations smaller than the previous H world data, but in good agreement with the µp value. We motivate an asymmetric fit function, which eliminates line shifts from quantum interference of neighboring atomic resonances.

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.

Frequency combs and precision spectroscopy of atomic hydrogen

2019 ◽  
pp. 142-215
Author(s):  
Thomas Udem
Keyword(s):  
High Resolution ◽  
Visible Light ◽  
Laser Spectroscopy ◽  
Quantum Electrodynamics ◽  
Atomic Hydrogen ◽  
Frequency Comb ◽  
Atomic Clock ◽  
Laser Frequency ◽  
High Resolution Spectroscopy ◽  
Frequency Combs

A laser frequency comb allows the phase coherent conversion of the very rapid oscillations of visible light of some 100s of THz down to frequencies that can be handled with conventional electronics. This capability has enabled the most precise laser spectroscopy experiments yet, which have allowed the testing of quantum electrodynamics, to determine fundamental constants and to construct an optical atomic clock. The chapter reviews the development of the frequency comb, derives its properties, and discusses its application for high resolution spectroscopy of atomic hydrogen.

scholarly journals MUONIC HYDROGEN AS A QUANTUM GRAVIMETER

2014 ◽  
Vol 23 (01) ◽  
pp. 1450005 ◽  
Author(s):  
ROBERTO ONOFRIO
Keyword(s):  
Weak Interactions ◽  
Muonic Hydrogen ◽  
Experimental Result ◽  
Detailed Knowledge ◽  
Gravitational Radius ◽  
Proton Charge ◽  
Proton Mass ◽  
Proton Charge Radius ◽  
The Standard Model ◽  
Electromagnetic Probes

High precision spectroscopy of muonic hydrogen has recently led to an anomaly in the Lamb shift, which has been parametrized in terms of a proton charge radius differing by seven standard deviations from the CODATA value. We show how this anomaly may be explained, within about a factor of three, in the framework of an effective Yukawian gravitational potential related to charged weak interactions, without additional free parameters with respect to the ones of the standard model. The residual discrepancy from the experimental result in this model should be attributable to the approximations introduced in the calculation, the uncertainty in the exact value of the Fermi scale relevant to the model and the lack of detailed knowledge on the gravitational radius of the proton. The latter cannot be inferred with electromagnetic probes due to the unknown gluonic contribution to the proton mass distribution. In this context, we argue that muonic hydrogen acts like a microscopic gravimeter suitable for testing a possible scenario for the reciprocal morphing between macroscopic gravitation and weak interactions, with the latter seen as the quantum, microscopic counterpart of the former.

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.

scholarly journals The proton radius puzzle – 9 years later

2020 ◽  
Vol 234 ◽  
pp. 01001 ◽  
Author(s):  
Jan C. Bernauer
Keyword(s):  
High Precision ◽  
Nuclear Physics ◽  
Muonic Hydrogen ◽  
Precision Measurements ◽  
Proton Radius ◽  
Short Summary ◽  
Proton Radius Puzzle

High-precision measurements of the proton radius via scattering, electric hydrogen spectroscopy and muonic hydrogen spectroscopy do not agree on the level of more than 5 σ. This proton radius puzzle persists now for almost a decade. This paper gives a short summary over the progress in the solution of the puzzle as well as an overview over the planned experiments to finally solve this puzzle at the interface of atomic and nuclear physics.

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

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