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Search Results: 1 - 10 of 201883 matches for " P. Huber "
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Impact of nuclear effects on the extraction of neutrino oscillation parameters
P. Coloma,P. Huber
Physics , 2013, DOI: 10.1103/PhysRevLett.111.221802
Abstract: We study the possible impact of nuclear effects and final state interactions on the determination of the oscillation parameters due to mis-reconstruction of non-quasi-elastic events as quasi-elastic events at low energies. We analyze a $\nu_\mu$ disappearance experiment using a water \v{C}erenkov detector. We find that, if completely ignored in the fit, nuclear effects can induce a significant bias in the determination of atmospheric oscillation parameters, particularly for the atmospheric mixing angle. Even after inclusion of a near detector a bias in the determination of the atmospheric mixing angle comparable to the statistical error remains.
Systematic Exploration of the Neutrino Factory Parameter Space including Errors and Correlations
M. Freund,P. Huber,M. Lindner
Physics , 2001, DOI: 10.1016/S0550-3213(01)00440-0
Abstract: We discuss in a systematic way the extraction of neutrino masses, mixing angles and leptonic CP violation at neutrino factories. Compared to previous studies we put a special emphasis on improved statistical methods and on the multidimensional nature of the combined fits of the nu_e -> nu_mu, \bar nu_e -> \bar nu_mu appearance and nu_mu -> nu_mu, \bar nu_mu -> \bar nu_mu disappearance channels. Uncertainties of all involved parameters and statistical errors are included. We find previously ignored correlations in the multidimensional parameter space, leading to modifications in the physics reach, which amount in some cases to one order of magnitude. Including proper statistical errors we determine for all parameters the improved sensitivity limits for various baselines, beam energies, neutrino fluxes and detector masses. Our results allow a comparison of the physics potential for different choices of baseline and beam energy with regard to all involved parameters. In addition we discuss in more detail the problem of parameter degeneracies in measurements of delta_CP.
Synergies between the first-generation JHF-SK and NuMI superbeam experiments
P. Huber,M. Lindner,W. Winter
Physics , 2002, DOI: 10.1016/S0550-3213(03)00063-4
Abstract: We discuss synergies in the combination of the first-generation JHF to Super-Kamiokande and NuMI off-axis superbeam experiments. With synergies we mean effects which go beyond simply adding the statistics of the two experiments. As a first important result, we do not observe interesting synergy effects in the combination of the two experiments as they are planned right now. However, we find that with minor modifications, such as a different NuMI baseline or a partial antineutrino running, one could do much richer physics with both experiments combined. Specifically, we demonstrate that one could, depending on the value of the solar mass squared difference, either measure the sign of the atmospheric mass squared difference or CP violation already with the initial stage experiments. Our main results are presented in a way that can be easily interpreted in terms of the forthcoming KamLAND result.
Extracting Matter Effects, Masses and Mixings at a Neutrino Factory
M. Freund,P. Huber,M. Lindner
Physics , 2000, DOI: 10.1016/S0550-3213(00)00369-2
Abstract: We discuss and quantify different possibilities to determine matter effects, the value and the sign of $Delta m^2_{31}$, as well as the magnitude of $\sin^2 2\theta_{13}$ in very long baseline neutrino oscillation experiments. We study neutrino oscillation at a neutrino factory in the $\nu_\mu\to\nu_\mu$ disappearance and $\nu_e\to\nu_\mu$ appearance channels with and without muon charge identification. One possibility is to analyze the $\nu_e\to\nu_\mu$ appearance channels leading to wrong sign muon events, which requires however very good muon charge identification. Without charge identification it is still possible to operate the neutrino factory both with $\mu^-$ and $\mu^+$ beams and to analyze the differences in the total neutrino event rate spectra. We show that this leads already to a quite good sensitivity, which may be important if right sign charge rejection capabilities are insufficient. With muon charge identification one can study the $\nu_\mu\to\nu_\mu$ disappearance and the $\nu_e\to\nu_\mu$ appearance channels independently. The best method is finally achieved by combining all available information of the $\nu_\mu\to\nu_\mu$ disappearance and $\nu_e\to\nu_\mu$ appearance channels with charge identification and we show the sensitivity which can be achieved.
R2D2 - a symmetric measurement of reactor neutrinos free of systematical errors
P. Huber,M. Lindner,T. Schwetz
Physics , 2004, DOI: 10.1088/1126-6708/2005/02/029
Abstract: We discuss a symmetric setup for a reactor neutrino oscillation experiment consisting of two reactors separated by about 1 km, and two symmetrically placed detectors, one close to each reactor. We show that such a configuration allows a determination of $\sin^22\theta_{13}$ which is essentially free of systematical errors, if it is possible to separate the contributions of the two reactors in each detector sufficiently. This can be achieved either by considering data when in an alternating way only one reactor is running or by directional sensitivity obtained from the neutron displacement in the detector.
Non-Standard Interactions: Atmospheric versus Neutrino Factory Experiments
P. Huber,J. W. F. Valle
Physics , 2001, DOI: 10.1016/S0370-2693(01)01319-3
Abstract: We consider the potential of a generic neutrino factory (NUFACT) in probing non-standard neutrino-matter interactions (NSI). We find that the sensitivity to flavour-changing (FC) NSI can be substantially improved with respect to present atmospheric neutrino data, especially at energies higher than approximately 50 GeV, where the effect of the tau mass is small. For example, a 100 GeV NUFACT can probe FC neutrino interactions at the level of few $|\epsilon| < {few} \times 10^{-4}$ at 99 % C.L.
Structural transformations of even-numbered n-alkanes confined in mesopores
Patrick Huber,Viktor P. Soprunyuk,Klaus Knorr
Physics , 2006, DOI: 10.1103/PhysRevE.74.031610
Abstract: The n-alkanes C12H26, C14H30, and C16H34 have been imbibed and solidified in mesoporous Vycor glass with a mean pore diameter of 10nm. The samples have been investigated by x-ray diffractometry and calorimetric measurements. The structures and phase sequences have been determined. Apart from a reduction and the hysteresis of the melting/freezing transition, pore confined C12 reproduces the liquid-triclinic phase sequence of the bulk material, but for C16 an orthorhombic rotator mesophase appears that in the bulk state is absent for C16 but well known from odd numbered alkanes of similar length. In pore confined C14 this phase shows up on cooling but not on heating.
Simulation of long-baseline neutrino oscillation experiments with GLoBES
P. Huber,M. Lindner,W. Winter
Physics , 2004, DOI: 10.1016/j.cpc.2005.01.003
Abstract: We present the GLoBES (``General Long Baseline Experiment Simulator'') software package, which allows the simulation of long-baseline and reactor neutrino oscillation experiments. One part of the software is the abstract experiment definition language to define experiments with beam and full detector descriptions as accurate as possible. Many systematics options are provided, such as normalization and energy calibration errors, or the choice between spectral or total rate information. For the definition of experiments, a new transparent building block concept is introduced. In addition, an additional program provides the possibility to develop and test new experiment definitions quickly. Another part of GLoBES is the user's interface, which provides probability, rate, and $\Delta \chi^2$ information for a given experiment or any combination of up to 32 experiments in C. Especially, the $\Delta \chi^2$ functions allow a simulation with statistics only, systematics, correlations, and degeneracies. In particular, GLoBES can handle the full multi-parameter correlation among the oscillation parameters, external input, and matter density uncertainties.
Resolving parameter degeneracies in long-baseline experiments by atmospheric neutrino data
P. Huber,M. Maltoni,T. Schwetz
Physics , 2005, DOI: 10.1103/PhysRevD.71.053006
Abstract: In this work we show that the physics reach of a long-baseline (LBL) neutrino oscillation experiment based on a superbeam and a megaton water Cherenkov detector can be significantly increased if the LBL data are combined with data from atmospheric neutrinos (ATM) provided by the same detector. ATM data are sensitive to the octant of $\theta_{23}$ and to the type of the neutrino mass hierarchy, mainly through three-flavor effects in e-like events. This allows to resolve the so-called $\theta_{23}$- and sign($\Delta m^2_{31}$)-parameter degeneracies in LBL data. As a consequence it becomes possible to distinguish the normal from the inverted neutrino mass ordering at $2\sigma$ CL from a combined LBL+ATM analysis if $\sin^2 2\theta_{13} \gtrsim 0.02$. The potential to identify the true values of $\sin^2 2\theta_{13}$ and the CP-phase $\delta_{cp}$ is significantly increased through the lifting of the degeneracies. These claims are supported by a detailed simulation of the T2K (phase II) LBL experiment combined with a full three-flavor analysis of ATM data in the HyperKamiokande detector.
On the challenge of reconstructing level-1 phylogenetic networks from triplets and clusters
P. Gambette,K. T. Huber,S. Kelk
Mathematics , 2015,
Abstract: Phylogenetic networks have gained prominence over the years due to their ability to represent complex non-treelike evolutionary events such as recombination or hybridization. Popular combinatorial objects used to construct them are triplet systems and cluster systems, the motivation being that any network $N$ induces a triplet system $\mathcal R(N)$ and a softwired cluster system $\mathcal S(N)$. Since in real-world studies it cannot be guaranteed that all triplets/softwired clusters induced by a network are available it is of particular interest to understand whether subsets of $\mathcal R(N)$ or $\mathcal S(N)$ allow one to uniquely reconstruct the underlying network $N$. Here we show that even within the highly restricted yet biologically interesting space of level-1 phylogenetic networks it is not always possible to uniquely reconstruct a level-1 network $N$ even when all triplets in $\mathcal R(N)$ or all clusters in $\mathcal S(N)$ are available. On the positive side, we introduce a reasonably large subclass of level-1 networks the members of which are uniquely determined by their induced triplet/softwired cluster systems. Along the way, we also establish various enumerative results, both positive and negative, including results which show that certain special subclasses of level-1 networks $N$ can be uniquely reconstructed from proper subsets of $\mathcal R(N)$ and $\mathcal S(N)$. We anticipate these results to be of use in the design of, for example, algorithms for phylogenetic network inference.
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