arXiv subjects

A. Bueno

Publications and source records attributed to A. Bueno.

136 records · Page 8Linked to original sources

arXiv2004

Statistical Pattern Recognition: Application to $ν_μ\toν_τ$ Oscillation Searches Based on Kinematic Criteria

Classic statistical techniques (like the multi-dimensional likelihood and the Fisher discriminant method) together with Multi-layer Perceptron and Learning Vector Quantization Neural Networks have been systematically used in order to find the best sensitivity when searching for $ν_μ\to ν_τ$ oscillations. We discovered that for a general direct $ν_τ$ appearance search based on kinematic criteria: a) An optimal discrimination power is obtained using only three variables ($E_{visible}$, $P_{T}^{miss}$ and $ρ_{l}$) and their correlations. Increasing the number of variables (or combinations of variables) only increases the complexity of the problem, but does not result in a sensible change of the expected sensitivity. b) The multi-layer perceptron approach offers the best performance. As an example to assert numerically those points, we have considered the problem of $ν_τ$ appearance at the CNGS beam using a Liquid Argon TPC detector.

hep-ph↗

arXiv2003

Supernova Neutrino Detection in a liquid Argon TPC

A liquid Argon TPC (ICARUS-like) has the ability to detect neutrino bursts from type-II supernova collapses, via three processes: elastic scattering by electrons from all neutrino species, and $ν_e$ charged current absorption on $Ar$ with production of excited $K$ and $\barν_e$ charged current absorption on $Ar$ with production of excited $Cl$. In this paper we have used new calculations in the random phase approximation (RPA) for the absorption processes. The anti-neutrino reaction $\barν_e ^{40}Ar$ absorption has been considered for the first time. For definiteness, we compute rates for the 3 kton ICARUS detector: 244 events are expected from a supernova at a distance of 10 kpc, without considering oscillation effects. The impact of oscillations in the neutrino rates will be discussed in a separate paper. We also discuss the ability to determine the direction of the supernova.

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arXiv2001

On the energy and baseline optimization to study effects related to the $δ$-phase (CP-/T-violation) in neutrino oscillations at a Neutrino Factory

In this paper we discuss the detection of CP and T-violation effects in the framework of a neutrino factory. We introduce three quantities, which are good discriminants for a non vanishing complex phase ($δ$) in the $3\times 3$ neutrino mixing matrix. We find that these three discriminants (in vacuum) all scale with $L/E_ν$. Matter effects modify the scaling, but these effects are large enough to spoil the sensitivity only for baselines larger than 5000 km. So, in the hypothesis of constant neutrino factory power, the sensitivity on the $δ$-phase is independent of the baseline chosen. Specially interesting is the direct measurement of T-violation from the ``wrong-sign'' electron channel, which involves a comparison of the $\nue\ra\numu$ and $\numu\ra\nue$ oscillation rates. However, the $\numu\ra\nue$ measurement requires magnetic discrimination of the electron charge, experimentally very challenging in a neutrino detector: low-energy neutrino beams and hence short baselines, are preferred. In this paper we show the exclusion regions in the $Δm^2_{12} - δ$ plane for two concrete cases. We obtain a similar excluded region provided that the electron detection efficiency is $\sim$20% and the charge confusion 0.1%. The $Δm^2_{12}$ compatible with the LMA solar data can be tested with a flux of 5$\times 10^{21}$ muons. We compare these results with the fit of the visible energy distributions.

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arXiv2000

The flavor of neutrinos in muon decays at a neutrino factory and the LSND puzzle

The accurate prediction of the neutrino beam produced in muon decays and the absence of opposite helicity contamination for a particular neutrino flavor make a future neutrino factory the ideal place to look for the lepton flavor violating (LFV) decays of the kind $μ^+\ra e^+\nuebar\numu$ and lepton number violating (LNV) processes like $μ^-\ra e^-\nue\numu$. Excellent sensitivities can be achieved using a detector capable of muon and/or electron identification with charge discrimination. This would allow to set experimental limits that improve current ones by more than two orders of magnitude and test the hypothesis that the LSND excess is due to such anomalous decays, rather than neutrino flavor oscillations in vacuum.

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arXiv2000

Physics at a Neutrino Factory

In response to the growing interest in building a Neutrino Factory to produce high intensity beams of electron- and muon-neutrinos and antineutrinos, in October 1999 the Fermilab Directorate initiated two six-month studies. The first study, organized by N. Holtkamp and D. Finley, was to investigate the technical feasibility of an intense neutrino source based on a muon storage ring. This design study has produced a report in which the basic conclusion is that a Neutrino Factory is technically feasible, although it requires an aggressive R&D program. The second study, which is the subject of this report, was to explore the physics potential of a Neutrino Factory as a function of the muon beam energy and intensity, and for oscillation physics, the potential as a function of baseline.

hep-ex↗

arXiv2000

Physics potential at a neutrino factory: can we benefit from more than just detecting muons?

In order to fully address the oscillation processes at a neutrino factory, a detector should be capable of identifying and measuring all three charged lepton flavors produced in charged current interactions {\it and} of measuring their charges to discriminate the incoming neutrino helicity. This is an experimentally challenging task, given the required detector mass for long-baseline experiments. We address the benefit of a high-granularity, excellent-calorimetry non-magnetized target-detector, which provides a background-free identification of electron neutrino charged current and a kinematical selection of tau neutrino charged current interactions. We assume that charge discrimination is only available for muons reaching an external magnetized-Fe spectrometer. This allows the clean classification of events into electron, right-sign muon, wrong-sign muon and no-lepton categories. In addition, high granularity permits a clean detection of quasi-elastic events, which by detecting the final state proton, provide a selection of the neutrino electron helicity without the need of an electron charge measurement. From quantitative analyses of neutrino oscillation scenarios, we conclude that in many cases the discovery sensitivities and the measurements of the oscillation parameters are dominated by the ability to measure the muon charge. However, we identify cases where identification of electron and tau samples contributes significantly.

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arXiv1999

Three-family oscillations using neutrinos from muon beams at very long baseline

The planned LBL experiments will be able to prove the hypothesis of flavor oscillation between muon and tau neutrinos. We explore the possibility of a second generation long baseline experiment at very long baseline, i.e. L in the range 5000-7000 km. This distance requires intense neutrino beams that could be available from very intense muon beams as those needed for $μ$ colliders. Such baselines allow the study of neutrino oscillations with $E/L \approx 2\times 10^{-3} eV^2$ with neutrinos of energy $E_ν\approx 10 GeV$, i.e. above tau threshold. Moreover, matter effects inside the Earth could lead to observable effects in $ν_e \to ν_μ$ oscillations. These effects are interchanged between neutrinos and antineutrinos, and therefore they can be tested by comparing the oscillated spectra obtained running the storage ring with positive and negative muons.

hep-ph↗

arXiv1998

A medium baseline search for $ν_μ\toν_e$ oscillations at a $ν$ beam from muon decays

The accurate knowledge of the $\barν_e (ν_μ)$ beam produced in $μ^-$ decays and the absence of $ν_e (\barν_μ)$ contamination, make a future muon storage ring the ideal place to look for $\numunue$ ($\numubarnuebar$) oscillations. Using a detector capable of electron and muon identification with charge discrimination (e.g., the presently running NOMAD experiment), good sensitivities to $\numunue (\numubarnuebar)$ oscillations could be achieved. With the CERN-PS as a proton driver for a muon storage ring of the kind envisaged for a $μ$-collider, the LSND claim would be confirmed or disproved in a few years of running.

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arXiv1998

Long baseline neutrino oscillation disappearance search using a $ν$ beam from muon decays

We study the feasibility of performing a $ν_μ$ disappearance long-baseline experiment using a neutrino beam coming from muon decays. The advantage of such a technique with respect to the production of neutrino beams from pions is that in a muon decay both muon and electron neutrinos are produced in the same quantity. In case of $ν_μ\toν_{τ,s}$ oscillations, the $ν_e$ charged current (CC) events can be used as a control sample, to predict in situ the $ν_μ$ rates, thus reducing the systematics due to the knowledge of the neutrino flux, which is the main source of uncertainties for disappearance experiments. We consider as our neutrino target, the ICARUS detector in its final mass configuration of 4.8 kton.

hep-ph↗

arXiv1996

A comparative study on two characteristic parametrizations for high energy pp and pp total cross sections

Available high energy data for both pp and pp total cross sections ($ 5 \ GeV \ < \ \sqrt s \ < \ 1.8 \ TeV$) are described by means of two well-known distinct parametrizations, characteristic of theoretical (``Regge-like" expression) and experimental (``Froissart-Martin-like" expression) practices, respectively. Both are compared from the statistical point of view. For the whole set of present data, statistical analysis ($χ^2/d.o.f.$) seems to favour a ``Froissart-like" ((ln $s$)$^{γ\approx 2}$ ) rise of the total cross section rather than a ``Regge-like" ($s^ε$) one.

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