Search results for "Digital libraries"
showing 10 items of 152 documents
SO(3) family symmetry and axions
2018
Motivated by the idea of comprehensive unification, we study a gauged SO(3) flavor extension of the extended Standard Model, including right-handed neutrinos and a Peccei-Quinn symmetry with simple charge assignments. The model accommodates the observed fermion masses and mixings and yields a characteristic, successful relation among them. The Peccei-Quinn symmetry is an essential ingredient.
Dynamical symmetry breaking and fermion mass hierarchy in the scale-invariant 3-3-1 model
2020
We propose an extension of the Standard Model (SM) based on the $SU(3)_C\otimes SU(3)_L\otimes U(1)_X$ (3-3-1) gauge symmetry and scale invariance. Maintaining the main features of the so-called 3-3-1 models, such as the cancellation of gauge anomalies related to the number of chiral fermion generations, this model exhibits a very compact scalar sector. Only two scalar triplets and one singlet are necessary and sufficient to break the symmetries dynamically via the Coleman-Weinberg mechanism. With the introduction of an Abelian discrete symmetry and assuming a natural hierarchy among the vacuum expectation values of the neutral scalar fields, we show that all particles in the model can get …
Next-to-leading order Balitsky-Kovchegov equation beyond large Nc
2020
We calculate finite-Nc corrections to the next-to-leading order (NLO) Balitsky-Kovchegov (BK) equation. We find analytical expressions for the necessary correlators of six Wilson lines in terms of the two-point function using the Gaussian approximation. In a suitable basis, the problem reduces from the diagonalization of a six-by-six matrix to the diagonalization of a three-by-three matrix, which can easily be done analytically. We study numerically the effects of these finite-Nc corrections on the NLO BK equation. In general, we find that the finite-Nc corrections are smaller than the expected 1/Nc2∼10%. The corrections may be large for individual correlators, but have less of an influence…
Testing WWγ vertex in radiative muon decay
2019
Large numbers of muons will be produced at facilities developed to probe the lepton-flavor-violating process μ→eγ. We show that by constructing a suitable asymmetry, radiative muon decay μ→eγνμν̄e can also be used to test the WWγ vertex at such facilities. The process has two missing neutrinos in the final state, and upon integrating their momenta the partial differential decay rate shows no radiation-amplitude zero. However, we establish that an easily separable part of the normalized differential decay rate that is odd under the exchange of photon and electron energies does have a zero in the case of the standard model (SM). This new type of zero has hitherto not been studied in the liter…
Flavor of cosmic neutrinos preserved by ultralight dark matter
2019
Within the standard propagation scenario, the flavor ratios of high-energy cosmic neutrinos at neutrino telescopes are expected to be around the democratic benchmark resulting from hadronic sources, $\left( 1 : 1 : 1 \right)_\oplus$. We show how the coupling of neutrinos to an ultralight dark matter complex scalar field would induce an effective neutrino mass that could lead to adiabatic neutrino propagation. This would result in the preservation at the detector of the production flavor composition of neutrinos at sources. This effect could lead to flavor ratios at detectors well outside the range predicted by the standard scenario of averaged oscillations. We also present an electroweak-in…
Enumerating higher-dimensional operators with on-shell amplitudes
2020
We establish a simple formula for the minimal dimension of operators leading to any helicity amplitude. It eases the systematic enumeration of independent operators from the construction of massless non-factorizable on-shell amplitudes. Little-group constraints can then be solved algorithmically for each helicity configuration to extract a complete set of spinor structures with lowest dimension. Occasionally, further reduction using momentum conservation, on-shell conditions and Schouten identities is required. A systematic procedure to account for the latter is presented. Dressing spinor structures with dot products of momenta finally yields the independent Lorentz structures for each heli…
Jet transition values for the anti-$$k_{\bot }$$ k⊥ algorithm
2019
We define jet transition values for the anti-$k_{\bot}$ algorithm for both hadron and $e^+e^-$ colliders. We show how these transition values can be computed and how they can be used to improve the performance of clusterization when jet resolution parameters are varied over a larger set of values. Finally we present a simple performance test to illustrate the behavior of the new method compared to the original one.
Chiral Instabilities and the Onset of Chiral Turbulence in QED Plasmas
2020
We present a first principles study of chiral plasma instabilities and the onset of chiral turbulence in QED plasmas far from equilibrium. By performing classical-statistical lattice simulations of the microscopic theory, we show that the generation of strong helical magnetic fields from a helicity imbalance in the fermion sector proceeds via three distinct phases. During the initial linear instability regime the helicity imbalance of the fermion sector causes an exponential growth(damping) of magnetic field modes with right(left) handed polarization, for which we extract the characteristic growth (damping) rates. Secondary growth of unstable modes accelerates the helicity transfer from fer…
Scotogenic dark matter and Dirac neutrinos from unbroken gauged B − L symmetry
2020
We propose a simple extension of the standard model where neutrinos get naturally small “scotogenic” Dirac masses from an unbroken gauged B−L symmetry, ensuring dark matter stability. The associated gauge boson gets mass through the Stueckelberg mechanism. Two scenarios are identified, and the resulting phenomenology briefly sketched.
Beta decay of 108Mo and of neighbouring even Mo-isotopes
1995
Abstract A combination of the proton-induced fission of 238 U and the on-line mass separation based on the ion-guide technique has been applied in the study of neutron-rich Mo-isotopes. The decays of 106,108 Mo have been studied by using gamma-, beta-, X-ray and conversion-electron spectroscopy. The decay scheme of 106 Mo has been revised and a beta-decay half-life of 8.73(12) s has been measured for this nucleus. A beta-decay half-life of 1.09(2) s and a decay energy of 5120(40) keV have been measured for 108 Mo. The decay scheme of 108 Mo has been constructed and altogether 29 new transitions have been placed in the decay scheme. The beta-decay strengths of 102,104,106,108 Mo have been de…