Related Experiment Video
Updated: May 14, 2025
07:46
Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
8.5K
New Physics Decaying into Metastable Particles: Impact on Cosmic Neutrinos
Kensuke Akita1, Gideon Baur2,3, Maksym Ovchynnikov2,4
1The University of Tokyo, Department of Physics, Bunkyo-ku, Tokyo 113-0033, Japan.
Physical Review Letters
|April 11, 2025
Summary
New physics particle decays in the early Universe affect cosmic neutrinos. Metastable particle dynamics alter neutrino properties, impacting Big Bang nucleosynthesis and cosmic microwave background observations.
Area of Science:
- Cosmology
- Particle Physics
- Astrophysics
Background:
- Investigates the early Universe's MeV temperature range.
- Considers decays of hypothetical new physics particles into metastable species like muons, pions, or kaons.
- Examines the impact of these decays on cosmic neutrinos.
Purpose of the Study:
- To understand how metastable particle dynamics in plasma modify the effects of new physics on neutrino populations.
- To analyze the influence on the effective number of neutrino degrees of freedom (Neff).
- To study modifications to neutrino spectral distortions and potential neutrino-antineutrino asymmetries.
Main Methods:
- Theoretical investigation of particle decays in the early Universe plasma.
- Analysis of metastable particle dynamics within the plasma environment.
- Modeling the impact on neutrino properties and cosmological observables.
Main Results:
- Demonstrates that metastable dynamics alter new physics impacts on neutrinos.
- Shows modifications to the effective number of neutrino degrees of freedom (Neff).
- Reveals potential for neutrino spectral distortions and energy distribution asymmetries.
Conclusions:
- Early Universe particle decays significantly affect cosmic neutrinos.
- Metastable dynamics introduce crucial modifications impacting cosmological observables like Big Bang nucleosynthesis and the cosmic microwave background.
- Findings are relevant for upcoming high-precision cosmic microwave background experiments targeting Neff.
Related Concept Videos
03:23Types of Radioactivity
16.2K
The most common types of radioactivity are α decay, β decay, γ decay, neutron emission, and electron capture.
Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:
Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:
16.2K
03:18Radioactivity and Nuclear Equations
20.5K
Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for hydrogen, neutrons. The number of protons in the nucleus is called the atomic number (Z) of the element, and the sum of the number of protons and the number of neutrons is the mass number (A). Atoms with the same atomic number but different mass numbers are isotopes of the same element.
A nuclide of an element has a specific number of protons and...
A nuclide of an element has a specific number of protons and...
20.5K
03:18Nuclear Stability
18.3K
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively...
To hold positively...
18.3K
03:20Nuclear Transmutation
17.3K
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed...
17.3K
01:20Momentum And Radiation Pressure
1.9K
An object absorbing an electromagnetic wave would experience a force in the direction of propagation of the wave. This force occurs because electromagnetic waves contain and transport momentum. The force accounts for the wave's radiation pressure exerted on the object. Maxwell's prediction was confirmed in 1903 by Nichols and Hull by precisely measuring radiation pressures with a torsion balance. The measuring instrument had mirrors suspended from a fiber kept inside a glass container.
1.9K
01:19Types of Collisions - II
6.8K
When two or more objects collide with each other, they can stick together to form one single composite object (after collision). The total mass of the object after the collision is the sum of the masses of the original objects, and it moves with a velocity dictated by the conservation of momentum. Although the system's total momentum remains constant, the kinetic energy decreases, and thus such a collision is an inelastic collision. Most of the collisions between objects in daily life are...
6.8K