6,550 research outputs found
Non-standard interaction effects on astrophysical neutrino fluxes
We investigate new physics effects in the production and detection of high
energy neutrinos at neutrino telescopes. Analysing the flavor ratios
\phi_\mu/\phi_\tau and \phi_\mu/(\phi_\tau+\phi_e), we find that the Standard
Model predictions for them can be sensibly altered by new physics effects.Comment: 21 pages, 9 figures, REVTeX
Extreme Value Laws for dynamical systems with countable extremal sets
We consider stationary stochastic processes arising from dynamical systems by
evaluating a given observable along the orbits of the system. We focus on the
extremal behaviour of the process, which is related to the entrance in certain
regions of the phase space, which correspond to neighbourhoods of the maximal
set , i.e. the set of points where the observable is maximised. The
main novelty here is the fact that we consider that the set may
have a countable number of points, which are associated by belonging to the
orbit of a certain point, and may have accumulation points. In order to prove
the existence of distributional limits and study the intensity of clustering,
given by the Extremal Index, we generalise the conditions previously introduced
in \cite{FFT12,FFT15}.Comment: arXiv admin note: text overlap with arXiv:1505.0155
Interplay between computable measures of entanglement and other quantum correlations
Composite quantum systems can be in generic states characterized not only by
entanglement, but also by more general quantum correlations. The interplay
between these two signatures of nonclassicality is still not completely
understood. In this work we investigate this issue focusing on computable and
observable measures of such correlations: entanglement is quantified by the
negativity N, while general quantum correlations are measured by the
(normalized) geometric quantum discord D_G. For two-qubit systems, we find that
the geometric discord reduces to the squared negativity on pure states, while
the relationship holds for arbitrary mixed states. The latter
result is rigorously extended to pure, Werner and isotropic states of two-qudit
systems for arbitrary d, and numerical evidence of its validity for arbitrary
states of a qubit and a qutrit is provided as well. Our results establish an
interesting hierarchy, that we conjecture to be universal, between two relevant
and experimentally friendly nonclassicality indicators. This ties in with the
intuition that general quantum correlations should at least contain and in
general exceed entanglement on mixed states of composite quantum systems.Comment: 10 pages, 4 figure
Black holes in the low mass gap: Implications for gravitational wave observations
Binary neutron-star mergers will predominantly produce black-hole remnants of
mass , thus populating the putative \emph{low mass gap}
between neutron stars and stellar-mass black holes. If these low-mass black
holes are in dense astrophysical environments, mass segregation could lead to
"second-generation" compact binaries merging within a Hubble time. In this
paper, we investigate possible signatures of such low-mass compact binary
mergers in gravitational-wave observations. We show that this unique population
of objects, if present, will be uncovered by the third-generation
gravitational-wave detectors, such as Cosmic Explorer and Einstein Telescope.
Future joint measurements of chirp mass and effective spin
could clarify the formation scenario of compact objects in the
low mass gap. As a case study, we show that the recent detection of GW190425
(along with GW170817) favors a double Gaussian mass model for neutron stars,
under the assumption that the primary in GW190425 is a black hole formed from a
previous binary neutron star merger.Comment: 8 pages, 4 figures, 1 table. v4: matches the version accepted for
publication in Phys. Rev.
Relativistic descriptions of final-state interactions in neutral-current neutrino-nucleus scattering at MiniBooNE kinematics
The analysis of the recent neutral-current neutrino-nucleus scattering cross
sections measured by the MiniBooNE Collaboration requires relativistic
theoretical descriptions also accounting for the role of final state
interactions. In this work we evaluate differential cross sections with the
relativistic distorted-wave impulse-approximation and with the relativistic
Green's function model to investigate the sensitivity to final state
interactions. The role of the strange-quark content of the nucleon form factors
is also discussed.Comment: 8 pages, 5 figure
Robust and efficient generator of almost maximal multipartite entanglement
Quantum chaotic maps can efficiently generate pseudo-random states carrying
almost maximal multipartite entanglement, as characterized by the probability
distribution of bipartite entanglement between all possible bipartitions of the
system. We show that such multipartite entanglement is robust, in the sense
that, when realistic noise is considered, distillable entanglement of
bipartitions remains almost maximal up to a noise strength that drops only
polynomially with the number of qubits.Comment: 4 pages, 4 figures. Published versio
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