scholarly journals Sun heated MeV-scale dark matter and the XENON1T electron recoil excess

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Yifan Chen ◽  
Ming-Yang Cui ◽  
Jing Shu ◽  
Xiao Xue ◽  
Guan-Wen Yuan ◽  
...  
Keyword(s):  
Dark Matter ◽  
Direct Detection ◽  
Structure Constant ◽  
Form Factors ◽  
Fine Structure Constant ◽  
Electron Interaction ◽  
Electron Mass ◽  
The Sun ◽  
Momentum Exchange ◽  
Electron Recoil

Abstract The XENON1T collaboration reported an excess of the low-energy electron recoil events between 1 and 7 keV. We explore the possibility to explain such an anomaly by the MeV-scale dark matter (DM) heated by the interior of the Sun due to the same DM-electron interaction as in the detector. The kinetic energies of heated DM particles can reach a few keV, and can potentially account for the excess signals detected by XENON1T. We study different form factors of the DM-electron interactions, F(q) ∝ qi with q being the momentum exchange and i = 0, 1, 2, and find that for all these cases the inclusion of the Sun-heated DM component improves the fit to the XENON1T data. The inferred DM-electron scattering cross section (at q = αme where α is the fine structure constant and me is electron mass) is from ∼ 10−38 cm2 (for i = 0) to ∼ 10−42 cm2 (for i = 2). We also derive constraints on the DM-electron cross sections for these form factors, which are stronger than previous results with similar assumptions. We emphasize that the Sun-heated DM scenario relies on the minimum assumption on DM models, which serves as a general explanation of the XENON1T anomaly via DM-electron interaction. The spectrum of the Sun-heated DM is typically soft comparing to other boosted DM, so the small recoil events are expected to be abundant in this scenario. More sensitive direct detection experiments with lower thresholds can possibly distinguish this scenario with other boosted DM models or solar axion models.

scholarly journals Testing the weak equivalence principle by differential measurements of fundamental constants in the Magellanic Clouds

2019 ◽  
Vol 487 (4) ◽  
pp. 5175-5187 ◽  
Author(s):  
S A Levshakov ◽  
K-W Ng ◽  
C Henkel ◽  
B Mookerjea ◽  
I I Agafonova ◽  
...  
Keyword(s):  
Dark Matter ◽  
Equivalence Principle ◽  
Structure Constant ◽  
Magellanic Clouds ◽  
Fine Structure Constant ◽  
Weak Equivalence ◽  
Electron Mass ◽  
Fundamental Constants ◽  
Weak Equivalence Principle ◽  
The Masses

ABSTRACT Non-standard fields are assumed to be responsible for phenomena attributed to dark energy and dark matter. Being coupled to ordinary matter, these fields modify the masses and/or charges of the elementary particles, thereby violating the weak equivalence principle. Thus, values of fundamental constants such as the proton-to-electron mass ratio, μ, and/or the fine structure constant, α, measured in different environment conditions can be used as probes for this coupling. Here we perform differential measurements of F = μα2 to test a non-standard coupling in the Magellanic Clouds–dwarf galaxies where the overall mass budget is dominated by dark matter. The analysis is based on [C i] and CO lines observed with the Herschel Space Observatory. Since these lines have different sensitivities to changes in μ and α, the combined α and μ variations can be evaluated through the radial velocity offsets, ΔV, between the CO and [C i] lines. Averaging over nine positions in the Magellanic Clouds, we obtain 〈ΔV〉 = −0.02 ± 0.07 km s−1, leading to |ΔF/F| < 2 × 10−7 (1σ), where ΔF/F = (Fobs − Flab)/Flab. However, for one position observed with five times higher spectral resolution we find ΔV = −0.05 ± 0.02 km s−1, resulting in ΔF/F = (−1.7 ± 0.7) × 10−7. Whether this offset is due to changes in the fundamental constants, due to chemical segregation in the emitting gas, or merely due to Doppler noise requires further investigations.

scholarly journals New Limit on Space-Time Variations in the Proton-to-Electron Mass Ratio from Analysis of Quasar J110325-264515 Spectra

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 344
Author(s):  
T. D. Le
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Space Time ◽  
Fine Structure Constant ◽  
Electron Mass ◽  
Mass Ratio ◽  
Quasar Spectra ◽  
Time Variations ◽  
Using Data ◽  
The Universe

Astrophysical tests of current values for dimensionless constants known on Earth, such as the fine-structure constant, α , and proton-to-electron mass ratio, μ = m p / m e , are communicated using data from high-resolution quasar spectra in different regions or epochs of the universe. The symmetry wavelengths of [Fe II] lines from redshifted quasar spectra of J110325-264515 and their corresponding values in the laboratory were combined to find a new limit on space-time variations in the proton-to-electron mass ratio, ∆ μ / μ = ( 0.096 ± 0.182 ) × 10 − 7 . The results show how the indicated astrophysical observations can further improve the accuracy and space-time variations of physics constants.

scholarly journals Sensitivity of direct detection experiments to neutrino magnetic dipole moments

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
D. Aristizabal Sierra ◽  
R. Branada ◽  
O. G. Miranda ◽  
G. Sanchez Garcia
Keyword(s):  
Dark Matter ◽  
Magnetic Dipole ◽  
Direct Detection ◽  
Dipole Moments ◽  
Nuclear Recoil ◽  
Active Volume ◽  
Electron Recoil ◽  
Flux Measurements ◽  
Neutrino Fluxes ◽  
One Year

Abstract With large active volume sizes dark matter direct detection experiments are sensitive to solar neutrino fluxes. Nuclear recoil signals are induced by 8B neutrinos, while electron recoils are mainly generated by the pp flux. Measurements of both processes offer an opportunity to test neutrino properties at low thresholds with fairly low backgrounds. In this paper we study the sensitivity of these experiments to neutrino magnetic dipole moments assuming 1, 10 and 40 tonne active volumes (representative of XENON1T, XENONnT and DARWIN), 0.3 keV and 1 keV thresholds. We show that with nuclear recoil measurements alone a 40 tonne detector could be as competitive as Borexino, TEXONO and GEMMA, with sensitivities of order 8.0 × 10−11μB at the 90% CL after one year of data taking. Electron recoil measurements will increase sensitivities way below these values allowing to test regions not excluded by astrophysical arguments. Using electron recoil data and depending on performance, the same detector will be able to explore values down to 4.0 × 10−12μB at the 90% CL in one year of data taking. By assuming a 200-tonne liquid xenon detector operating during 10 years, we conclude that sensitivities in this type of detectors will be of order 10−12μB. Reducing statistical uncertainties may enable improving sensitivities below these values.

scholarly journals Fundamental physics and the fine-structure constant

2017 ◽  
Vol 5 (2) ◽  
pp. 46 ◽  
Author(s):  
Michael Sherbon
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Electron Mass ◽  
Fundamental Constants ◽  
Mass Ratio ◽  
Fundamental Physics ◽  
Weak Force ◽  
Strong Force ◽  
Symmetry Principles

From the exponential function of Euler’s equation to the geometry of a fundamental form, a calculation of the fine-structure constant and its relationship to the proton-electron mass ratio is given. Equations are found for the fundamental constants of the four forces of nature: electromagnetism, the weak force, the strong force and the force of gravitation. Symmetry principles are then associated with traditional physical measures.

scholarly journals Speed of sound from fundamental physical constants

2020 ◽  
Vol 6 (41) ◽  
pp. eabc8662
Author(s):  
K. Trachenko ◽  
B. Monserrat ◽  
C. J. Pickard ◽  
V. V. Brazhkin
Keyword(s):  
Speed Of Sound ◽  
Structure Constant ◽  
Point Of View ◽  
Fine Structure Constant ◽  
Electron Mass ◽  
Large Set ◽  
Fundamental Physical Constants ◽  
Physical Constants ◽  
Dimensionless Constant ◽  
Fundamental Physical

Two dimensionless fundamental physical constants, the fine structure constant α and the proton-to-electron mass ratio mpme, are attributed a particular importance from the point of view of nuclear synthesis, formation of heavy elements, planets, and life-supporting structures. Here, we show that a combination of these two constants results in a new dimensionless constant that provides the upper bound for the speed of sound in condensed phases, vu. We find that vuc=α(me2mp)12, where c is the speed of light in vacuum. We support this result by a large set of experimental data and first-principles computations for atomic hydrogen. Our result expands the current understanding of how fundamental constants can impose new bounds on important physical properties.

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