Search results for "Degeneracy"
showing 10 items of 46 documents
Accurate Evaluation of Fermi-Dirac Integrals and Their Derivatives for Arbitrary Degeneracy and Relativity
1996
The equation of state of an ideal Fermi gas is expressed in terms of Fermi-Dirac integrals. We give formulae for evaluation the Fermi-Dirac integrals of orders 1/2, 3/2, and 5/2 and their derivatives in various limits of non- and extreme degeneracy and relativity. We provide tables and a Fortran subroutine for numerical evaluation of the integrals and derivatives when a limit does not apply. The functions can be evaluated to better than 1% accuracy for any temperature and density using these methods.
Confusing Head-On Collisions with Precessing Intermediate-Mass Binary Black Hole Mergers
2021
We report a degeneracy between the gravitational-wave signals from quasi-circular precessing black-hole mergers and those from extremely eccentric mergers, namely head-on collisions. Performing model selection on numerically simulated signals of head-on collisions using models for quasi-circular binaries we find that, for signal-to-noise ratios of 15 and 25, typical of Advanced LIGO observations, head-on mergers with respective total masses of $M\in (125,300)M_\odot$ and $M\in (200,440)M_\odot$ would be identified as precessing quasi-circular intermediate-mass black hole binaries, located at a much larger distance. Ruling out the head-on scenario would require to perform model selection usi…
Relativistic Magnetohydrodynamics: Renormalized eigenvectors and full wave decomposition Riemann solver
2010
We obtain renormalized sets of right and left eigenvectors of the flux vector Jacobians of the relativistic MHD equations, which are regular and span a complete basis in any physical state including degenerate ones. The renormalization procedure relies on the characterization of the degeneracy types in terms of the normal and tangential components of the magnetic field to the wavefront in the fluid rest frame. Proper expressions of the renormalized eigenvectors in conserved variables are obtained through the corresponding matrix transformations. Our work completes previous analysis that present different sets of right eigenvectors for non-degenerate and degenerate states, and can be seen as…
Turnstile behaviour of the Cooper-pair pump
2003
We have experimentally studied the behaviour of the so-called Cooper pair pump (CPP) with three Josephson junctions, in the limit of small Josephson coupling EJ < EC. These experiments show that the CPP can be operated as a traditional turnstile device yielding a gate-induced current 2ef in the direction of the bias voltage, by applying an RF-signal with frequency f to the two gates in phase, while residing at the degeneracy node of the gate plane. Accuracy of the CPP during this kind of operation was about 3% and the fundamental Landau-Zener limit was observed to lie above 20 MHz. We have also measured the current pumped through the array by rotating around the degeneracy node in the ga…
Leptonic CP Violation measurement at the neutrino factory
2003
Abstract In this talk, based on the work [J. Burguet Castell, et al., Nucl. Phys. B 608 (2001) 301], we refine our previous analysis [A. Cervera, et al., Nucl. Phys. B 579 (2000) 17] of the sensitivity to leptonic CP violation and θ 13 at a neutrino factory in the LMA-MSW scenario, by exploring the full range of these two parameters. We have discovered that there exist, at fixed neutrino energy, E ν , and baseline, L, degenerate solutions. Although the spectral analysis helps in disentangling fake from true solutions, a leftover product of this degeneracy remains for a realistic detector, which we analyse. Furthermore, we take into account the expected uncertainties on the solar and atmosph…
Are solar neutrino oscillations robust?
2004
The robustness of the large mixing angle (LMA) oscillation (OSC) interpretation of the solar neutrino data is considered in a more general framework where non-standard neutrino interactions (NSI) are present. Such interactions may be regarded as a generic feature of models of neutrino mass. The 766.3 ton-yr data sample of the KamLAND collaboration are included in the analysis, paying attention to the background from the reaction ^13C(\alpha,n) ^16O. Similarly, the latest solar neutrino fluxes from the SNO collaboration are included. In addition to the solution which holds in the absence of NSI (LMA-I) there is a 'dark-side' solution (LMA-D) with sin^2 theta_Sol = 0.70, essentially degenerat…
Subleading effects in the 1-2 sector: Non-standard neutrino interactions
2005
We have reconsidered the status of the large mixing angle (LMA) oscillation (OSC) interpretation of the solar neutrino data in a more general framework where non-standard neutrino interactions (NSI) are present. Using the latest data from all solar neutrino experiments and KamLAND we have found the existence of three LMA solutions, instead of the unique solution which holds in the absence of NSI, LMA-I. In addition to LMA-I, there is another solution with smaller Δ m 2 (LMA-0), and a new “dark-side” solution (LMA-D) with sin 2 θ = 0.70 . We comment on the potential of KamLAND and future solar neutrino experiments using 7Be and 8B neutrinos to lift the degeneracy between the LMA-I, LMA-0 and…
Parameter Degeneracy in Flavor-Dependent Reconstruction of Supernova Neutrino Fluxes
2008
We reexamine the possibility of reconstructing the initial fluxes of supernova neutrinos emitted in a future core-collapse galactic supernova explosion and detected in a Megaton-sized water Cherenkov detector. A novel key element in our method is the inclusion, in addition to the total and the average energies of each neutrino species, of a "pinching" parameter characterizing the width of the distribution as a fit parameter. We uncover in this case a continuous degeneracy in the reconstructed parameters of supernova neutrino fluxes at the neutrinosphere. We analyze in detail the features of this degeneracy and show how it occurs irrespective of the parametrization used for the distribution …
Determination of the $\theta_{23}$ octant in LBNO
2014
According to the recent results of the neutrino oscillation experiment MINOS, the neutrino mixing angle $\theta_{23}$ may not be maximal ($45^{\circ}$). Two nearly degenerate solutions are possible, one in the lower octant (LO) where $\theta_{23}45^{\circ}$. Long baseline experiments measuring the $\nu_{\mu}\rightarrow\nu_{e}$ are capable of resolving this degeneracy. In this work we study the potential of the planned European LBNO experiment to distinguish between the LO and HO solutions.
Measuring the leptonic CP phase in neutrino oscillations with nonunitary mixing
2017
Non-unitary neutrino mixing implies an extra CP violating phase that can fake the leptonic Dirac CP phase $\delta_{CP}$ of the simplest three-neutrino mixing benchmark scheme. This would hinder the possibility of probing for CP violation in accelerator-type experiments. We take T2K and T2HK as examples to demonstrate the degeneracy between the "standard" (or "unitary") and "non-unitary" CP phases. We find, under the assumption of non-unitary mixing, that their CP sensitivities severely deteriorate. Fortunately, the TNT2K proposal of supplementing T2(H)K with a $\mu$DAR source for better measurement of $\delta_{CP}$ can partially break the CP degeneracy by probing both $\cos \delta_{CP}$ and…