Search results for "Elementary particle"
showing 10 items of 659 documents
Modell einer Coulombschen Ladung in der nichtlinearen Feldtheorie
1960
>The nonlinear field theory developed by K. Bechert has solutions which correspond to a charged particle whose charge is represented by a charge density which is zero in the particle center, increases to a maximum against the particle edges, and then again decreases. The linear expansion of the particles was measured by the characteristic length L, which accurately represents the classical particle radius; for an electron L is equal to the classical electron radius. The physical magnitudes integrated over a random spatial area are all infinite. In the theory a dimensionless number of the order-of-magnitude of 10/ sup 4//sup 2/ occurs. The particle was held together by gravitational forces w…
First search for atmospheric and extraterrestrial neutrino-induced cascades with the IceCube detector
2011
We report on the first search for atmospheric and for diffuse astrophysical neutrino-induced showers (cascades) in the IceCube detector using 257 days of data collected in the year 2007-2008 with 22 strings active. A total of 14 events with energies above 16 TeV remained after event selections in the diffuse analysis, with an expected total background contribution of $8.3\pm 3.6$. At 90% confidence we set an upper limit of $E^2\Phi_{90%CL}<3.6\times10^{-7} GeV \cdot cm^{-2} \cdot s^{-1}\cdot sr^{-1} $ on the diffuse flux of neutrinos of all flavors in the energy range between 24 TeV and 6.6 PeV assuming that $\Phi \propto E^{-2}$ and that the flavor composition of the $\nu_e : \nu_\mu : \nu…
Elementary Goldstone Higgs boson and dark matter
2015
We investigate a perturbative extension of the Standard Model featuring elementary pseudo-Goldstone Higgs and dark matter particles. These are two of the five Goldstone bosons parametrising the SU(4)/Sp(4) coset space. They acquire masses, and therefore become pseudo-Goldstone bosons, due to the embedding of the Yukawa and the electroweak gauge interactions that do not preserve the full SU(4) symmetry. At the one-loop order the top corrections dominate and align the vacuum in the direction where the Higgs is mostly a pseudo-Goldstone boson. Because of the perturbative and elementary nature of the theory, the quantum corrections are precisely calculable. The remaining pseudo-Goldstone boson …
Non-abelian gauge structure in neutrino mixing
2010
We discuss the existence of a non-abelian gauge structure associated with flavor mixing. In the specific case of two flavor mixing of Dirac neutrino fields, we show that this reformulation allows to define flavor neutrino states which preserve the Poincar\'e structure. Phenomenological consequences of our analysis are explored.
Sum rules for light-by-light scattering
2010
We derive a set of sum rules for the light-by-light scattering and fusion: $\gamma\gamma \to all$, and verify them in lowest order QED calculations. A prominent implication of these sum rules is the superconvergence of the helicity-difference total cross-section for photon fusion, which in the hadron sector reveals an intricate cancellation between the pseudoscalar and tensor mesons. An experimental verification of superconvergence of the polarized photon fusion into hadrons is called for, but will only be possible at $e^+ e^-$ and $\gamma\gamma$ colliders with both beams polarized. We also show how the sum rules can be used to measure various contributions to the low-energy light-by-light …
Inflation might be caused by the right
2009
15 pages, 4 figures.-- ISI article identifier: 000265600800102.-- ArXiv pre-print avaible at: http://arxiv.org/abs/0811.2998
Light Dark Matter Search with Ionization Signals in XENON1T
2019
We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4 keVee, we observe <1 event/(tonne day keVee), which is more than 1000 times lower than in similar searches with other detectors. Despite observing a higher rate at lower energies, no DM or CEvNS detection may be claimed because we cannot model all of our backgrounds. We thus exclude new regions in the parameter spaces for DM-nucleus scattering for DM masses mχ within 3–6 GeV/c2, DM-electron scattering for mχ>30 MeV/c2, a…
Neutrino masses, Majorons, and muon decay
1987
5 páginas, 3 figuras.
Hyperchargeless triplet Majoron model.
1989
We study the general conditions to maintain the scale of the lepton-number-breaking vacuum expectation value at the electroweak scale. It is shown that the only possibilities are if the main component of the resulting Majoron is a hyperchargeless complex triplet or a neutral singlet. Models with a hyperchargeless triplet, even though phenomenologically more interesting, seem to be very difficult to build because they like to break charge conservation. However, we have found a particular extension, by adding an additional neutral singlet, that solves this problem. The model can give a Majorana mass to the neutrinos in the eV range, ..mu -->..e..gamma.. can proceed with branching ratios at th…
Meson-retardation effects in deuteron photodisintegration below ?-threshold
1989
Mesor-retardation effects in photodisintegration of the deuteron below pion threshold are studied by constructing retarded one-boson-exchange potentials using time-dependent non-covariant perturbation theory. The corresponding retarded meson-exchange currents including retarded vertex currents are derived analogously by gauge-invariant minimal coupling. It is found that retardation effects in the wave functions and in the electromagnetic currents as well have a significant influence on total and differential cross sections.