Search results for "Orders of Magnitude"
showing 10 items of 188 documents
DIRECT PRODUCTION OF PIONIC ATOMS FROM RADIATIVE TRAPPING OF PIONS IN FLIGHT
1992
Abstract The reaction π−A→(πb−A)γ with Tπ=10−30 MeV producing a π− bound in the nucleus is studied to see its viability as an instrument to produce deeply bound pionic atoms in nuclei. We obtain cross sections of the order of tens of μb/ (sr MeV) for the production of the 1s and 2p states of 208Pb and negligible background from radiative pion capture and the other sources. The negligible background expected in the present reaction is unique among all other reactions so far proposed. The cross sections obtained are three orders of magnitude bigger than those in the best electromagnetic reactions previously proposed. The small background, the large cross sections and the present available flu…
Some comments on the n + p --> d + 2 gamma anomaly
1975
Abstract It is shown that the only theoretical contribution to the doubly radiative emission, not included in the two-step transition radiations, is given by charge-bremsstrahlung from the single-photon emission. Due to the pole structure of the amplitude, the experimental energy spectrum is reproduced, but the rate is short of the measured value by more than six orders of magnitude.
Triple resonant four-wave mixing boosts the yield of continuous coherent vacuum ultraviolet generation.
2012
Efficient continuous-wave four-wave mixing by using three different fundamental wavelengths with individual detunings to resonances of the nonlinear medium is shown. Up to 6 μW of vacuum ultraviolet light at 121 nm can be generated, which corresponds to an increase of three orders of magnitude in efficiency. This opens the field of quantum information processing by Rydberg entanglement of trapped ions.
Precision Test of Many-Body QED in theBe+2pFine Structure Doublet Using Short-Lived Isotopes
2015
Absolute transition frequencies of the $2s\text{ }{^{2}S}_{1/2}\ensuremath{\rightarrow}2p\text{ }{^{2}P}_{1/2,3/2}$ transitions in ${\mathrm{Be}}^{+}$ were measured for the isotopes $^{7,9--12}\mathrm{Be}$. The fine structure splitting of the $2p$ state and its isotope dependence are extracted and compared to results of ab initio calculations using explicitly correlated basis functions, including relativistic and quantum electrodynamics effects at the order of $m{\ensuremath{\alpha}}^{6}$ and $m{\ensuremath{\alpha}}^{7} \mathrm{ln} \ensuremath{\alpha}$. Accuracy has been improved in both the theory and experiment by 2 orders of magnitude, and good agreement is observed. This represents on…
Dark Matter Bound States from Three-Body Recombination
2020
The small-scale structure problems of the universe can be solved by self-interacting dark matter that becomes strongly interacting at low energies. A particularly predictive model is resonant short-range self-interactions, with a dark-matter mass of about 19 GeV and a large S-wave scattering length of about 17 fm. Such a model makes definite predictions for the few-body physics of weakly bound clusters of the dark-matter particles. We calculate the production of two-body bound clusters by three-body recombination in the early universe under the assumption that the dark matter particles are identical bosons, which is the most favorable case for forming larger clusters. The fraction of dark m…
Direct limits on the interaction of antiprotons with axion-like dark matter
2019
Astrophysical observations indicate that there is roughly five times more dark matter in the Universe than ordinary baryonic matter, with an even larger amount of the Universe's energy content due to dark energy. So far, the microscopic properties of these dark components have remained shrouded in mystery. In addition, even the five percent of ordinary matter in our Universe has yet to be understood, since the Standard Model of particle physics lacks any consistent explanation for the predominance of matter over antimatter. Inspired by these central problems of modern physics, we present here a direct search for interactions of antimatter with dark matter, and place direct constraints on th…
Mass bounds for baryogenesis from particle decays and the inert doublet model
2014
In models for thermal baryogenesis from particle decays, the mass of the decaying particle is typically many orders of magnitude above the TeV scale. We will discuss different ways to lower the energy scale of baryogenesis and present the corresponding lower bounds on the particle's mass. This is done specifically for the inert doublet model with heavy Majorana neutrinos and then we indicate how to extrapolate the results to other scenarios. We also revisit the question of whether or not dark matter, neutrino masses, and the cosmic baryon asymmetry can be explained simultaneously at low energies in the inert doublet model.
Constraints on neutrino speed, weak equivalence principle violation, Lorentz invariance violation, and dual lensing from the first high-energy astrop…
2019
We derive stringent constraints on neutrino speed, weak equivalence principle violation, Lorentz invariance violation, and dual lensing from the first high-energy astrophysical neutrino source: TXS $0506+056$. Observation of neutrino (IceCube-170922A) and photons in a similar time frame and from the same direction is used to derive these limits. We describe ways in which these constraints can be further improved by orders of magnitude.
Rare CP-violated η and η′ meson decays and neutron EDM.
2018
The data for the upper limit on the electric dipole moment of the neutron (nEDM) can be explained by using different mechanisms beyond the Standard Model (SM). The nEDM can be generated by a CP-violating transition of η and η′ mesons into pion pairs. We derive the upper limits for the rates of the CP-violating decays η(η′) → 2π are by orders of magnitude more stringent than those from existing experiments so far.
New Methods of Scalar Dark Matter Detection
2017
In this chapter, I consider new mechanisms for the induction of a cosmological evolution of the fundamental constants (such as the electromagnetic fine-structure constant \(\alpha \) and the particle masses) by dark matter. By investigating the effects of “slow drifts” and oscillating variations of the fundamental constants due to dark matter in astrophysical phenomena, including Big Bang nucleosynthesis and cosmic microwave background radiation measurements, and laboratory clock-comparison experiments, I derive new limits on certain interactions of dark matter with ordinary matter that improve on previous limits by up to 15 orders of magnitude, as well as the first ever limits on several o…