Search results for "Fundamental interaction"
showing 10 items of 20 documents
Short-range fundamental forces
2011
Abstract We consider theoretical motivations to search for extra short-range fundamental forces as well as experiments constraining their parameters. The forces could be of two types: 1) spin-independent forces; 2) spin-dependent axion-like forces. Different experimental techniques are sensitive in respective ranges of characteristic distances. The techniques include measurements of gravity at short distances, searches for extra interactions on top of the Casimir force, precision atomic and neutron experiments. We focus on neutron constraints, thus the range of characteristic distances considered here corresponds to the range accessible for neutron experiments.
Challenges for solid state detectors tracking detectors in nuclear physics experiments at FAIR
2007
The compelling scientific goals of future nuclear physics experiments demand significant advances in detector technology. Nuclear physics opportunities at future facility FAIR have never been so bright, but the detector challenges must be met. With the essential questions concerning nuclear structure and dynamics, nuclear astrophysics, limits of nuclear stability, tests of fundamental interactions and symmetries all being realistic targets of studies of exotic nuclei, detector development efforts are strongly motivated. Several examples of developments for future fixed target experiments as well as experiments at storage ring are outlined.
The Standard Model
2002
Publisher Summary The weak interactions of the elementary particles are discovered in β-decay processes. They are described by an effective Lagrangian of current × current type in which the weak currents are coherent superpositions of charged vector and axial-vector currents, accounting for the violation of parity. The Fermi theory of the weak interactions can only be interpreted as an effective low-energy theory that cannot be extended to arbitrarily high energies. Applying this theory to the scattering process at high energies, the scattering amplitude rises indefinitely with the square of the energy. The structure of the electroweak system that has emerged from the requirement of asympto…
Mass and Gravity
2014
The book starts with a survey on the development of the concept ‘mass’ and of theories of gravity, beginning with Greek’s ideas on mass, Galileo’s experiments, Newton’s laws and their extension by Einstein’s theory of relativity. Data from measurements of the gravitational force on Sun, planets and the Moon are presented. Kepler’s laws on moving masses in the gravitational field are discussed as well as new discoveries on the expansion of the universe. Fundamental interactions of particles and particle/wave duality are described. The Theory of Everything is mentioned. The definition of the international unit of mass is reported as well as alternatives like watt or voltage balance, counting …
5 QCD on the Lattice
2008
Since Wilson’s seminal papers of the mid-1970s, the lattice approach to Quantum Chromodynamics has become increasingly important for the study of the strong interaction at low energies, and has now turned into a mature and established technique. In spite of the fact that the lattice formulation of Quantum Field Theory has been applied to virtually all fundamental interactions, it is appropriate to discuss this topic in a chapter devoted to QCD, since by far the largest part of activity is focused on the strong interaction. Lattice QCD is, in fact, the only known method which allows ab initio investigations of hadronic properties, starting from the QCD Lagrangian formulated in terms of quark…
Topological magneto-optical effects and their quantization in noncoplanar antiferromagnets
2018
Reflecting the fundamental interactions of polarized light with magnetic matter, magneto-optical effects are well known since more than a century. The emergence of these phenomena is commonly attributed to the interplay between exchange splitting and spin-orbit coupling in the electronic structure of magnets. Using theoretical arguments, we demonstrate that topological magneto-optical effects can arise in noncoplanar antiferromagnets due to the finite scalar spin chirality, without any reference to exchange splitting or spin-orbit coupling. We propose spectral integrals of certain magneto-optical quantities that uncover the unique topological nature of the discovered effect. We also find th…
First-forbidden transitions in reactor antineutrino spectra
2019
© 2019 American Physical Society. We study the dominant forbidden transitions in the antineutrino spectra of the fission actinides from 4 MeV onward using the nuclear shell model. Through explicit calculation of the shape factor, we show the expected changes in cumulative electron and antineutrino spectra. Relative to the allowed approximation this results in a minor decrease of electron spectra above 4 MeV, whereas an increase of several percent is observed in antineutrino spectra. We show that forbidden transitions dominate the spectral flux for most of the experimentally accessible range. Based on the shell model calculations we attempt a parametrization of forbidden transitions and prop…
Muon-electron lepton-flavor-violating transitions : Shell-model calculations of transitions in 27Al
2018
In this paper we present the results of large-scale shell-model calculations of muon-to-electron lepton-flavorviolating transitions for the case of the target nucleus 27Al. We extend the previous shell-model calculations, done in the sd model space, by including also the p orbitals in order to see whether the negative-parity states produce any significant effect in the conversion rate. The analysis of the results shows the dominance of coherent transitions mediated by isovector operators and going by the ground state of the target, with practically null influence of excited positive- or negative-parity states. peerReviewed
Analysis of light neutrino exchange and short-range mechanisms in 0νββ decay
2020
Neutrinoless double beta decay (0νββ) is a crucial test for lepton number violation. Observation of this process would have fundamental implications for neutrino physics, theories beyond the Standard Model and cosmology. Focusing on so-called short-range operators of 0νββ and their potential interplay with the standard light Majorana neutrino exchange, we present the first complete calculation of the relevant nuclear matrix elements, performed within the interacting boson model (IBM-2). Furthermore, we calculate the relevant phase space factors using exact Dirac electron wave functions, taking into account the finite nuclear size and screening by the electron cloud. The obtained numerical r…