scholarly journals Analysis of Experimental Cross-Sections of Charge Exchange between Hydrogen Atoms and Protons Yields More Evidence of the Existence of the Second Flavor of Hydrogen Atoms

Foundations ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 265-270
Author(s):  
Eugene Oks
Keyword(s):  
Dark Matter ◽  
Charge Exchange ◽  
Cross Sections ◽  
Anomalous Absorption ◽  
Hydrogen Atoms ◽  
Experimental Cross ◽  
Standard Cosmology ◽  
Theoretical Predictions ◽  
The Status ◽  
Noticeable Discrepancy

Measurements of cross-sections of charge exchange between hydrogen atoms and low energy protons (down to the energy ~10 eV) revealed a noticeable discrepancy with previous theories. The experimental cross-sections were systematically slightly higher—beyond the error margins—than the theoretical predictions. In the present paper, we study whether this discrepancy can be eliminated or at least reduced by using the Second Flavor of Hydrogen Atoms (SFHA) in calculations. We show that for the SFHA, the corresponding cross-section is noticeably larger than for the usual hydrogen atoms. We demonstrate that the allowance for the SFHA does bring the theoretical cross-sections in a noticeably better agreement with the corresponding experiments within the experimental error margins. This seems to constitute yet another evidence from atomic experiments that the SFHA is present within the mixture of hydrogen atoms. In combination with the first corresponding piece of evidence from the analysis of atomic experiments (concerning the distribution of the linear momentum in the ground state of hydrogen atoms), as well as with the astrophysical evidence from two different kinds of observations (the anomalous absorption of the redshifted 21 cm radio line from the early universe and the smoother distribution of dark matter than that predicted by the standard cosmology), the results of the present paper reinforce the status of the SFHA as the candidate for dark matter, or at least for a part of it.

scholarly journals Classical Description of Resonant Charge Exchange Involving the Second Flavor of Hydrogen Atoms

Atoms ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 41
Author(s):  
Eugene Oks
Keyword(s):  
Perturbation Theory ◽  
Electric Field ◽  
Charge Exchange ◽  
Cross Sections ◽  
Stark Effect ◽  
Uniform Electric Field ◽  
Hydrogen Atoms ◽  
Additional Tool ◽  
Classical Description ◽  
Resonant Charge Exchange

We studied the consequences of the existence of the second flavor of hydrogen atoms (SFHA)—the existence proven by atomic experiments and evidenced by astrophysical observations—on the resonant charge exchange. We found analytically that there is indeed an important difference in the corresponding cross-sections for the SFHA compared to the usual hydrogen atoms. This difference could serve as an additional tool for distinguishing between the two kinds of hydrogen atoms in future experiments/observations. We also show that the SFHA does not exhibit any Stark effect—whether in a uniform or a non-uniform electric field—in any order of the perturbation theory.

Lyman–α excitation and resonant charge exchange in slow H+–H(1s) collisions

1970 ◽  
Vol 48 (3) ◽  
pp. 313-329 ◽  
Author(s):  
Stephen K. Knudson ◽  
Walter R. Thorson
Keyword(s):  
Charge Exchange ◽  
Cross Sections ◽  
Hydrogen Atoms ◽  
Resonant Charge Exchange ◽  
Straight Line ◽  
Classical Path ◽  
Sensitive Function ◽  
Interference Oscillations ◽  
The Impact ◽  
Excitation Probability

The dominant processes in slow collisions (E < 0.5 keV) of protons and 1s hydrogen atoms are direct elastic scattering, resonant charge exchange, and direct and exchange excitations of H(2p). Differential cross sections have been calculated for all these events by both quantal and classical methods, and characteristics of the resulting Lyman–α (Ly–α) radiation determined.Significant differences from earlier calculations are found for excitation probability, polarization of Ly–α, and the interference oscillations in the charge exchange probability. The phase of the latter is a sensitive function of the interactions causing inelastic scattering. The source of discrepancy with earlier results is the use of the impact parameter approximation (straight-line trajectories); over the range of significant excitation probability, classical path methods using true trajectories give accurate inelastic parameters. Comparison of quantal and classical calculations shows that accurate results for all properties discussed can be obtained by combining classical path calculations of inelastic parameters with semi-classical phase shifts for pure elastic scattering.If polarizations calculated here are used to reinterpret earlier observations of Ly–α emission from 300 eV collisions, the resulting experimental cross sections are not inconsistent with the basic theoretical prediction of equal direct and exchange excitation probabilities.

scholarly journals Measurements and Theoretical Predictions of Charge Exchange Cross Sections and Emission Spectra for O6+with H2O, CO, CO2, CH4, N2, NO, N2O and Ar

2015 ◽  
Vol 635 (2) ◽  
pp. 022076
Author(s):  
J R Machacek ◽  
D P Mahapatra ◽  
D R Schultz ◽  
Yu Ralchenko ◽  
A Moradmand ◽  
...  
Keyword(s):  
Charge Exchange ◽  
Cross Sections ◽  
Emission Spectra ◽  
Theoretical Predictions

DARK MATTER SEARCH

2002 ◽  
Vol 17 (24) ◽  
pp. 3421-3431 ◽  
Author(s):  
◽  
H. V. KLAPDOR-KLEINGROTHAUS
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Exciting Field ◽  
Dark Matter Search ◽  
The Status

Dark matter is at present one of the most exciting field of particle physics and cosmology. We review the status of undergound experiments looking for cold and hot dark matter.

scholarly journals Relativistic impulse approximation in the atomic ionization process induced by millicharged particles

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Chen-Kai Qiao ◽  
Shin-Ted Lin ◽  
Hsin-Chang Chi ◽  
Hai-Tao Jia
Keyword(s):  
Dark Matter ◽  
Cross Sections ◽  
Direct Detection ◽  
Impulse Approximation ◽  
Dark Matter Particle ◽  
Ionization Process ◽  
Beyond The Standard Model ◽  
Next Generation ◽  
Many Body ◽  
Atomic Ionization

Abstract The millicharged particle has become an attractive topic to probe physics beyond the Standard Model. In direct detection experiments, the parameter space of millicharged particles can be constrained from the atomic ionization process. In this work, we develop the relativistic impulse approximation (RIA) approach, which can duel with atomic many-body effects effectively, in the atomic ionization process induced by millicharged particles. The formulation of RIA in the atomic ionization induced by millicharged particles is derived, and the numerical calculations are obtained and compared with those from free electron approximation and equivalent photon approximation. Concretely, the atomic ionizations induced by mllicharged dark matter particles and millicharged neutrinos in high-purity germanium (HPGe) and liquid xenon (LXe) detectors are carefully studied in this work. The differential cross sections, reaction event rates in HPGe and LXe detectors, and detecting sensitivities on dark matter particle and neutrino millicharge in next-generation HPGe and LXe based experiments are estimated and calculated to give a comprehensive study. Our results suggested that the next-generation experiments would improve 2-3 orders of magnitude on dark matter particle millicharge δχ than the current best experimental bounds in direct detection experiments. Furthermore, the next-generation experiments would also improve 2-3 times on neutrino millicharge δν than the current experimental bounds.

scholarly journals Measurements of the differential cross sections of the production of Z + jets and γ + jets and of Z boson emission collinear with a jet in pp collisions at $$ \sqrt{s} $$ = 13 TeV

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
◽  
A. M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Cross Sections ◽  
Differential Cross ◽  
Z Boson ◽  
Center Of Mass ◽  
Z Bosons ◽  
Differential Cross Sections ◽  
Pp Collisions ◽  
Center Of Mass Energy ◽  
Cms Experiment ◽  
Theoretical Predictions

Abstract Measurements of the differential cross sections of Z + jets and γ + jets production, and their ratio, are presented as a function of the boson transverse momentum. Measurements are also presented of the angular distribution between the Z boson and the closest jet. The analysis is based on pp collisions at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 35.9 fb−1 recorded by the CMS experiment at the LHC. The results, corrected for detector effects, are compared with various theoretical predictions. In general, the predictions at higher orders in perturbation theory show better agreement with the measurements. This work provides the first measurement of the ratio of the differential cross sections of Z + jets and γ + jets production at 13 TeV, as well as the first direct measurement of Z bosons emitted collinearly with a jet.

scholarly journals Experimental study of the $ \gamma p \rightarrow K^{0}\Sigma^{+}$, $ \gamma n \rightarrow K^{0} \Lambda$, and $ \gamma n \rightarrow K^{0} \Sigma^{0}$ reactions at the Mainz Microtron

2019 ◽  
Vol 55 (11) ◽  
Author(s):  
C. S. Akondi ◽  
K. Bantawa ◽  
D. M. Manley ◽  
S. Abt ◽  
P. Achenbach ◽  
...  
Keyword(s):  
Experimental Study ◽  
Cross Sections ◽  
Differential Cross ◽  
Legendre Polynomials ◽  
Neutral Kaon ◽  
Experimental Results ◽  
Differential Cross Sections ◽  
Theoretical Predictions ◽  
Photoproduction Reactions ◽  
Insight Into

Abstract.This work measured $ \mathrm{d}\sigma/\mathrm{d}\Omega$dσ/dΩ for neutral kaon photoproduction reactions from threshold up to a c.m. energy of 1855MeV, focussing specifically on the $ \gamma p\rightarrow K^0\Sigma^+$γp→K0Σ+, $ \gamma n\rightarrow K^0\Lambda$γn→K0Λ, and $ \gamma n\rightarrow K^0 \Sigma^0$γn→K0Σ0 reactions. Our results for $ \gamma n\rightarrow K^0 \Sigma^0$γn→K0Σ0 are the first-ever measurements for that reaction. These data will provide insight into the properties of $ N^{\ast}$N* resonances and, in particular, will lead to an improved knowledge about those states that couple only weakly to the $ \pi N$πN channel. Integrated cross sections were extracted by fitting the differential cross sections for each reaction as a series of Legendre polynomials and our results are compared with prior experimental results and theoretical predictions.

System-wide seismic vulnerability of aging multiple-span multiple-girder bridges in low-to-moderate seismic hazard regions

2021 ◽  
Vol 37 (1_suppl) ◽  
pp. 1626-1651
Author(s):  
John E Lens M.EERI ◽  
Mandar M Dewoolkar ◽  
Eric M Hernandez M.EERI
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
Cross Sections ◽  
Seismic Vulnerability ◽  
Time History ◽  
The United States ◽  
National Database ◽  
Eastern United States ◽  
Girder Bridges ◽  
The Status

This article describes the approach, methods, and findings of a quantitative analysis of the seismic vulnerability in low-to-moderate seismic hazard regions of the Central and Eastern United States for system-wide assessment of typical multiple span bridges built in the 1950s through the 1960s. There is no national database on the status of seismic vulnerability of bridges, and thus no means to estimate the system-wide damage and retrofit costs for bridges. The study involved 380 nonlinear analyses using actual time-history records matched to four representative low-to-medium hazard target spectra corresponding with peak ground accelerations from approximately 0.06 to 0.3 g. Ground motions were obtained from soft and stiff site seismic classification locations and applied to models of four typical multiple-girder with concrete bent bridges. Multiple-girder bridges are the largest single category, comprising 55% of all multiple span bridges in the United States. Aging and deterioration effects were accounted for using reduced cross-sections representing fully spalled conditions and compared with pristine condition results. The research results indicate that there is an overall low likelihood of significant seismic damage to these typical bridges in such regions, with the caveat that certain bridge features such as more extensive deterioration, large skews, and varied bent heights require bridge-specific analysis. The analysis also excludes potential damage resulting from liquefaction, flow-spreading, or abutment slumping due to weak foundation or abutment soils.

Charge exchange reactions on medium and heavy mass targets at intermediate energies

2019 ◽  
Vol 35 (08) ◽  
pp. 2050045
Author(s):  
Pardeep Singh ◽  
Monika Singh ◽  
Neha Rani
Keyword(s):  
Charge Exchange ◽  
Cross Sections ◽  
Energy Charge ◽  
Impulse Approximation ◽  
Mass Region ◽  
Intermediate Energy ◽  
Exchange Reactions ◽  
Plane Wave Impulse Approximation ◽  
Text Type ◽  
Intermediate Energies

The nuclear isotopic structure can be understood easily via the intermediate-energy charge exchange reactions of (p, n) and [Formula: see text]He, [Formula: see text] type. In the current contribution, we present some results for charge exchange reactions induced by 3He on targets lying in mass region [Formula: see text] within the theoretical framework of plane wave impulse approximation (PWIA) and distorted wave impulse approximation (DWIA). Here, the recoil effects in PWIA have also been considered. Particularly, the angular distributions and the unit cross-sections have been calculated and compared with the available data. Further, the importance of inclusion of the exchange contribution in these reactions is also considered, which eventually enhance the matching with data.

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