8,557 research outputs found
Revisiting the production of ALPs at B-factories
In this paper, the production of Axion-Like Particles (ALPs) at B-factories via the process e+e− → γa is revisited. To this purpose, the relevant cross-section is computed via an effective Lagrangian with simultaneous ALP couplings to b-quarks and photons. The interplay between resonant and non-resonant contributions is shown to be relevant for experiments operating at s=mϒ(nS), with n = 1, 2, 3, while the non-resonant one dominates at ϒ(4S). These effects imply that the experimental searches performed at different quarkonia resonances are sensitive to complementary combinations of ALP couplings. To illustrate these results, constraints from existing BaBar and Belle data on ALPs decaying into invisible final states are derived, and the prospects for the Belle-II experiment are discussedThe authors acknowledge F. Anulli, D. Becirevic, S. Fajfer, A. Guerrera, C. Hearty,
S.J.D. King, T. Ferben, S. Lacaprara, M. Margoni, F. Mescia, M. Passera and P. Paradisi for very useful exchanges. This project has received support by the European Union’s
Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant
agreement N◦ 674896 (ITN Elusives) and 690575 (RISE InvisiblePlus) and by the exchange
of researchers project “The flavor of the invisible universe” funded by the Italian Ministry
of Foreign Affairs and International Cooperation (MAECI). L.M. acknowledges partial
financial support by the Spanish MINECO through the “Ram´on y Cajal” programme
(RYC-2015-17173), by the Spanish “Agencia Estatal de Investigaci´on” (AEI) and the EU
“Fondo Europeo de Desarrollo Regional” (FEDER) through the project FPA2016-78645-P,
and through the Centro de excelencia Severo Ochoa Program under grant SEV-2016-0597.
L.M. thanks the Physics and Astronomy Department ‘G.Galilei’ of the Universit`a degli
Studi di Padova for hospitality during the development of this projec
Fourier transform based procedure for investigations on the grid frequency signal
The continuous growth of PV and wind sources makes the inertia of power systems decrease and creates larger frequency deviations. Frequency oscillation is a stochastic signal and, consequently, it could be complex to compare the effectiveness of different control approaches devoted to manage this problem. In this paper a Fourier transform procedure is proposed in order to define a standard frequency oscillation and to set up the dynamic model of the electric grid. The final goal is to numerically simulate a realistic transient behavior; using this grid, such a model results to be the ideal starting point for evaluating the effectiveness of different possible approaches to manage the energy balance problem
LFV and Dipole Moments in Models with A4 Flavour Symmetry
It is presented an analysis on lepton flavour violating transitions, leptonic
magnetic dipole moments and electric dipole moments in a class of models
characterized by the flavour symmetry A4 x Z3 x U(1)_FN, whose choice is
motivated by the approximate Tri-Bimaximal mixing observed in neutrino
oscillations. A low-energy effective Lagrangian is constructed, where these
effects are dominated by dimension six operators, suppressed by the scale M of
new physics. All the flavour breaking effects are universally described by the
vacuum expectation values of a set of spurions. Two separate cases, a
supersymmetric and a general one, are described. An upper limit on the reactor
angle of a few percent is concluded.Comment: 10 pages, 1 figure. Adapted from a talk given at "DISCRETE'08:
Symposium on Prospects in the Physics of Discrete Symmetries", December 11-16
2008, Valencia, Spai
Relevance of multiple-quasiparticle tunneling between edge states at \nu =p/(2np+1)
We present an explanation for the anomalous behavior in tunneling conductance
and noise through a point contact between edge states in the Jain series
, for extremely weak-backscattering and low temperatures [Y.C.
Chung, M. Heiblum, and V. Umansky, Phys. Rev. Lett. {\bf{91}}, 216804 (2003)].
We consider edge states with neutral modes propagating at finite velocity, and
we show that the activation of their dynamics causes the unexpected change in
the temperature power-law of the conductance. Even more importantly, we
demonstrate that multiple-quasiparticles tunneling at low energies becomes the
most relevant process. This result will be used to explain the experimental
data on current noise where tunneling particles have a charge that can reach
times the single quasiparticle charge. In this paper we analyze the
conductance and the shot noise to substantiate quantitatively the proposed
scenario.Comment: 4 pages, 2 figure
Bringing global gyrokinetic turbulence simulations to the transport timescale using a multiscale approach
The vast separation dividing the characteristic times of energy confinement
and turbulence in the core of toroidal plasmas makes first-principles
prediction on long timescales extremely challenging. Here we report the
demonstration of a multiple-timescale method that enables coupling global
gyrokinetic simulations with a transport solver to calculate the evolution of
the self-consistent temperature profile. This method, which exhibits resiliency
to the intrinsic fluctuations arising in turbulence simulations, holds
potential for integrating nonlocal gyrokinetic turbulence simulations into
predictive, whole-device models.Comment: 7 pages, 3 figure
Global gyrokinetic simulations of ITG turbulence in the configuration space of the Wendelstein 7-X stellarator
We study the effect of turbulent transport in different magnetic
configurations of the Weldenstein 7-X stellarator. In particular, we performed
direct numerical simulations with the global gyrokinetic code GENE-3D, modeling
the behavior of Ion Temperature Gradient turbulence in the Standard,
High-Mirror, and Low-Mirror configurations of W7-X. We found that the
Low-Mirror configuration produces more transport than both the High-Mirror and
the Standard configurations. By comparison with radially local simulations, we
have demonstrated the importance of performing global nonlinear simulations to
predict the turbulent fluxes quantitatively
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