53526002
Improvement of the low energy neutrino factory
The low energy neutrino factory has been proposed as a very sensitive setup for future searches for CP violation and matter effects. Here we study how its performance is affected when the experimental specifications of the setup are varied. Most notably, we have considered the addition of the ‘platinum’ �µ ! �e channel. We find that, whilst theoretically the extra channel provides very useful complementary information and helps to lift degeneracies, its practical usefulness is lost when considering realistic background levels. Conversely, an increase in statistics in the ‘golden’ �e ! �µ channel and, to some extent, an improvement in the energy resolution, lead to an important increase in the performance of the facility, given the rich energy dependence of the ‘golden’ channel at these energies. We show that a low energy neutrino factory with a baseline of 1300 km, muon energy of 4.5 GeV, and either a 20 kton totally active scintillating detector or 100 kton liquid argon detector, can have outstanding sensitivity to the neutrino oscillation parameters �13, � and the mass hierarchy. For our estimated exposure of 2.8×10 23 kton × decays per muon polarity, the low energy
118554862
Exploring the Earth matter effect with atmospheric neutrinos in ice
We study the possibility to perform neutrino oscillation tomography and to determine the neutrino mass hierarchy in kilometer-scale ice Cerenkov detectors by means of the theta13-driven matter effects which occur during the propagation of atmospheric neutrinos deep through the Earth. We consider the ongoing IceCube/DeepCore neutrino observatory and future planned extensions, such as the PINGU detector, which has a lower energy threshold. Our simulations include the impact of marginalization over the neutrino oscillation parameters and a fully correlated systematic uncertainty on the total number of events. For the current best-fit value of the mixing angle theta13, the DeepCore detector, due to its relatively high-energy threshold, could only be sensitive to fluctuations on the normalization of the Earth's density of \Delta\rho \simeq \pm 10% at ~ 1.6 sigma CL after 10 years in the case of a true normal hierarchy. For the two PINGU configurations we consider, overall density fluctuations of \Delta\rho \simeq \pm 3% (\pm 2%) could be measured at the 2 sigma CL after 10 years, also in the case of a normal mass hierarchy. We also compare the prospects to determine the neutrino mass hierarchy in these three configurations and find that this could be achieved at the 5 sigma CL, for both hierarchies, after 5 years in DeepCore and about 1 year in PINGU. This clearly shows the importance of lowering the energy threshold below 10 GeV so that detectors are fully sensitive to the resonant matter effects.
118464873
A Comparative Study of Long-Baseline Superbeams within LAGUNA for large $\theta_{13}$
The Daya Bay and RENO experiments have recently observed a non-zero $\theta_{13}$ at more than $5\sigma$ CL. This has important consequences for future neutrino oscillation experiments. We analyze these within the LAGUNA design study which considers seven possible locations for a European neutrino observatory for proton decay, neutrino, and astroparticle physics. The megaton-scale detector would be an ideal target for a CERN-based neutrino beam with baselines ranging from 130 km to 2300 km. We perform a detailed study to assess the physics reach of the three detector options - a 440 kton water \v{C}erenkov, a 100 kton liquid argon and a 50 kton liquid scintillator detector - at each of the possible locations, taking into account the recent measurement of $\theta_{13}$. We study the impact of the beam properties and detector performances on the sensitivity to CP-violation and the mass hierarchy. We find that a liquid argon or water \v{C}erenkov detector can make a $3\sigma$ discovery of CP violation for $60%-70%$ of the parameter space for any of the baselines under consideration, although the results for the liquid argon detector placed at 130 km are slightly worse and only $40%-50%$ is achieved in this case. The performance of the liquid scintillator detector is affected by its level of neutral-current background at all baselines. A $3\sigma$ determination of the mass hierarchy is possible for all values of $\delta$, for the values of $\theta_{13}$ favoured at $3\sigma$ by Daya Bay and RENO, for almost all setups with $L\gtrsim 650$ km.
117068481
Phenomenology of a Low-Energy Neutrino Factory and Related Experiments
The discovery of neutrino oscillations is one of the most important in the recent history of particle physics, being the first evidence of physics beyond the Standard Model. We describe the theoretical framework of the neutrino oscillation model, motivate the necessity for a new generation of neutrino oscillation experiments and study the phenomenological factors which influence the design of these experiments. 
 
We perform the first detailed study of a European super-beam setup using the CERN to Pyhasalmi baseline of 2285 km, analysing the physics reach of this setup with a 100 kiloton liquid argon detector and comparing its performance to that of a 50 kiloton liquid scintillator detector and a 440 kiloton water Cerenkov detector. The liquid argon and liquid scintillator detectors are found to perform best, providing sensitivity to theta_{13}, delta and the mass hierarchy for sin^{2}2theta_{13} > 10^{-2}. 
 
A potential successor to super-beam experiments is a neutrino factory. We study a low-energy neutrino factory, a setup which has so far not been analysed in any detail, performing optimisation studies and an analysis of its sensitivity to oscillation parameters and non-standard matter interactions. We show that for sin^{2}2theta_{13} > 4x10^{-3}, a low-energy neutrino factory using a 20 kiloton totally active scintillating detector has 100% CP coverage for hierarchy sensitivity and theta_{13} discovery, and has greater sensitivity to CP violation than the high-energy neutrino factory. We consider the novel concept of including the `platinum channels' in addition to the `golden channels', showing that this is a powerful way of resolving the degeneracies between the oscillation and non-standard parameters. This enhances the sensitivity, such that the low-energy neutrino factory can put upper bounds \gtrsim10^{-2} on the non-standard interaction parameters epsilon_{e\mu} and epsilon_{e\tau}.
119268605
An incremental approach to unravel the neutrino mass hierarchy and CP violation with a long-baseline superbeam for large θ13
A bstractRecent data from long-baseline neutrino oscillation experiments have provided new information on θ13, hinting that $ 0.0{1}\mathop{ < }\limits_{ \sim } {\text{si}}{{\text{n}}^{{2}}} $$ {2}{\theta_{{{13}}}}\mathop{ < }\limits_{ \sim } 0.{1} $ at 2 σ confidence level. In the near future, further confirmation of this result with high significance will have a crucial impact on the optimization of the future long-baseline neutrino oscillation experiments designed to probe the neutrino mass ordering and leptonic CP violation. In this context, we expound in detail the physics reach of an experimental setup where neutrinos produced in a conventional wide-band beam facility at CERN are observed in a proposed Giant Liquid Argon detector at the Pyhasalmi mine, at a distance of 2290 km. Due to the strong matter effects and the high detection efficiency at both the first and second oscillation maxima, this particular setup would have unprecedented sensitivity to the neutrino mass ordering and leptonic CP violation in the light of the emerging hints of large θ13. With a 10 to 20 kt ‘pilot’ detector and just a few years of neutrino beam running, the neutrino mass hierarchy could be determined, irrespective of the true values of δCP and the mass hierarchy, at 3 σ (5 σ) confidence level if sin2 2θ13(true) = 0.05 (0.1). With the same exposure, we start to have 3 σ sensitivity to CP violation if sin2 2θ13(true) > 0.05, in particular testing maximally CP-violating scenarios at a high confidence level. After optimizing the neutrino and anti-neutrino running fractions, we study the performance of the setup as a function of the exposure, identifying three milestones to have roughly 30%, 50% and 70% coverage in δC P (true) for 3 σ CP violation discovery. For comparison, we also study the CERN to Slanic baseline of 1540 km. This work nicely demonstrates that an incremental program, staged in terms of the exposure, can achieve the desired physics goals within a realistically feasible timescale, and produce significant new results at each stage.
118633851
Long-baseline super-beam experiments in Europe within LAGUNA
We explore the physics reach of several possible configurations for a Super-Beam experiment in Europe, focusing on the possibilities of discovering θ13, CP violation in the leptonic sector and the ordering of neutrino mass eigenstates. We consider the three different detector technologies: Water Cerenkov, Liquid Argon and Liquid Scintillator, and seven possible sites in Europe which would be able to host such a detector underground. The distances to these sites from CERN, where the beam would be originated, go from 130 km to 2300 km. The neutrino flux is optimized in each case as to match the first oscillation peak for each of the baselines under consideration. We also study the impact of several experimental factors in the performance of each detector technology.
14976799
X-Ray Variability Coherence in the Time Domain
A technique for calculation of variability coherence at different timescales performed directly in the time domain is introduced. Simulations are made to compare the coherence spectrum derived by the time-domain technique with the coherence function derived by Fourier analysis. The results indicate that in comparison with the Fourier analysis the time-domain technique is more powerful for revealing signal coherence in noisy data. We apply the time-domain technique to real data of the black hole binaries Cygnus X-1 and GX 339-4 and compare the results with their Fourier coherence spectra.
118555439
Attraction-repulsion coupled and energy conserved universe
The discovery of accelerated cosmic expansion implies that, in addition to the attractive gravity of matter, there exists in our universe some other form of energy (dark energy or cosmological constant) producing a repulsive force. The natural interpretation of dark energy is the vacuum energy. However, the density of vacuum energy expected by the quantum field theory is 120 orders of magnitude larger than what is allowed by cosmological observations, which is called the cosmological constant problem and remains one of the most significant unsolved problems in fundamental physics. Here we show that the huge discrepancy can be resolved by assuming that our universe is an attraction-repulsion coupled system with energy conservation, and that the pre-inflation vacuum is in equilibrium between attraction and repulsion (in flat Minkowski spacetime, not de Sitter or anti de Sitter). The attraction-repulsion coupling picture can also easily explain why both kinds of energy in our universe have similar magnitude today, and avoid singularity problems in general relativity and cosmology.
1506194
TIGER: A data analysis pipeline for testing the strong-field dynamics of general relativity with gravitational wave signals from coalescing compact binaries
The direct detection of gravitational waves with upcoming second-generation gravitational wave observatories such as Advanced LIGO and Advanced Virgo will allow us to probe the genuinely strong-field dynamics of general relativity (GR) for the first time. We have developed a data analysis pipeline called TIGER (test infrastructure for general relativity), which uses signals from compact binary coalescences to perform a model-independent test of GR. In this paper we focus on signals from coalescing binary neutron stars, for which sufficiently accurate waveform models are already available which can be generated fast enough on a computer that they can be used in Bayesian inference. By performing numerical experiments in stationary, Gaussian noise, we show that for such systems, TIGER is robust against a number of unmodeled fundamental, astrophysical, and instrumental effects, such as differences between waveform approximants, a limited number of post-Newtonian phase contributions being known, the effects of neutron star tidal deformability on the orbital motion, neutron star spins, and instrumental calibration errors.
117073878
Imaging in Hard X-ray Astronomy
The energy range of hard X-rays is a key waveband to the study of high energy processes in celestial objects, but still remains poorly explored. In contrast to direct imaging methods used in the low energy X-ray and high energy gamma-ray bands, currently imaging in the hard X-ray band is mainly achieved through various modulation techniques. A new inversion technique, the direct demodulation method, has been developed since early 90s. With this technique, wide field and high resolution images can be derived from scanning data of a simple collimated detector. The feasibility of this technique has been confirmed by experiment, balloon-borne observation and analyzing simulated and real astronomical data. Based the development of methodology and instrumentation, a high energy astrophysics mission - Hard X-ray Modulation Telescope (HXMT) has been proposed and selected in China for a four-year Phase-A study. The main scientific objectives are a full-sky hard X-ray (20-200 keV) imaging survey and high signal-to-noise ratio timing studies of high energy sources.
118385730
Testing general relativity using gravitational waves from binary neutron stars: Effect of spins
We present a Bayesian data analysis pipeline for testing GR using gravitational wave signals from coalescing compact binaries, and in particular binary neutron stars. In this study, we investigate its performance when sources with spins are taken into account.