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A. Donini

Publications and source records attributed to A. Donini.

At least 109 records · Page 6Linked to original sources
arXiv2006

Future neutrino oscillation facilities

The recent discovery that neutrinos have masses opens a wide new field of experimentation. Accelerator-made neutrinos are essential in this program. Ideas for future facilities include high intensity muon neutrino beams from pion decay (`SuperBeam'), electron neutrino beams from nuclei decays (`Beta Beam'), or muon and electron neutrino beams from muon decay (`Neutrino Factory'), each associated with one or several options for detector systems. Each option offers synergetic possibilities, e.g. some of the detectors can be used for proton decay searches, while the Neutrino Factory is a first step towards muon colliders. A summary of the perceived virtues and shortcomings of the various options, and a number of open questions are presented.

hep-ph↗
arXiv2006

$ν_μ$ disappearance at the SPL, T2K-I, NO$ν$A and the Neutrino Factory

We study the measurement of the atmospheric neutrino oscillation parameters, $θ_{23}$ and $Δm^2_{23}$, at the $ν_μ$ disappearance channel at three conventional beam facilities, the SPL, T2K-phase I and NO$ν$A. These two parameters have been shown to be of crucial importance in the measurement of two of the unknowns of the PMNS mixing matrix, $θ_{13}$ and the leptonic CP-violating phase $δ$. In our analyis, the effect of the two discrete ambiguities, ${\rm sign}(Δm^2_{23})$ and ${\rm sign}(\tan 2 θ_{23})$, is explicitly taken into account. We analyse also the $ν_μ$ disappearance channel at the Neutrino Factory, and combine it with the ``golden'' $ν_e \to ν_μ$ and ``silver'' $ν_e \to ν_τ$ appearance channels to study its impact on the measurement of $θ_{13}$ and $δ$. Eventually, we present the sensitivity of the four facilities to different observables: $θ_{13}$, $δ$, maximal $θ_{23}$, the sign of the atmospheric mass difference, $s_{atm}$, and the $θ_{23}$-octant, $s_{oct}$.

hep-ph↗
arXiv2005

Perspectives for a neutrino program based on the upgrades of the CERN accelerator complex

In this paper, we discuss the possibilities offered to neutrino physics by the upgrades of the CERN accelerator complex. Emphasis is on the physics reach of a medium $γ$ (350-580) $β$-beam that fully exploits the improvements in the CERN accelerator complex for the luminosity/energy upgrade of the LHC. We show that, this design not only profits of the ongoing efforts for the upgrades of the LHC, but also leverage out the existing infrastructures of the LNGS underground laboratory. Furthermore, given the involved high neutrino energies, above 1 GeV, a non-magnetized iron detector could efficiently exploit the neutrino beam. We show that the performance of this complex for what concerns the discovery of the CP violation in the leptonic sector, in case $θ_{13}$ is discovered by Phase I experiments, is comparable with the current baseline design based on a gigantic water Cherenkov at Frejus. Furthermore, this complex has also some sensitivity to the neutrino mass hierarchy.

hep-ph↗
arXiv2005

The impact of solar and atmospheric parameter uncertainties on the measurement of $θ_{13}$ and $δ$

We present in this paper the analysis of the measurement of the unknown PMNS parameters $θ_{13}$ and $δ$ at future LBL facilities performing complete three parameters fits, each time fully including in the fit one of the atmospheric and solar oscillation parameters within its present (future) error. We show that, due to the presence of degeneracies, present uncertainties on $θ_{23}$ and $Δm^2_{23}$ worsen significantly the precision on ($θ_{13}$,$δ$) at future LBL experiments. Only if a precision on the atmospheric parameters at least similar to what expected at T2K-I is reached, then the sensitivities to $θ_{13}$ and $δ$ that have been presented in the literature for many facilities (where $θ_{23}$ and $Δm^2_{23}$ are generally considered as fixed external inputs) can indeed be almost recovered.On the other hand, the impact on this measurement of the uncertainties on the solar parameters, $θ_{12}$ and $Δm^2_{12}$ is already negligible. Our analysis has been performed using three reference setups: the SPL Super-Beam and the standard low-$γ$ $β$-Beam, both aiming toward a Mton Water Čerenkov detector located at L=130 km; the 50 GeV Neutrino Factory with a 40 kton Magnetized Iron Detector to look for the ``golden channel'' $ν_e \to ν_μ$ with baseline L=3000 km and a 4 kton Emulsion Cloud Chamber to look for the ``silver channel'' $ν_e \to ν_τ$ with baseline L=732 km.

hep-ph↗
arXiv2005

$ν_μ$ disappearance at the SPL, T2K-I and the Neutrino Factory

We study the $ν_μ$ disappearance channel at T2K-phase I and the SPL and analyse the achievable reduction of present uncertainties in $θ_{23}$ and $Δm^2_{23}$. We analyse the impact of discrete ambiguities in sign($Δm^2{23}$) and sign($2 \tan θ_{23}$). We show how the disappearance channel at the Neutrino Factory is complementary to the ``golden'' and ``silver'' appearance channels and can be used to reduce the eightfold-ambiguity problem in ($θ_{13}-δ$).

hep-ph↗
arXiv2005

Appearance and disappearance signals at a beta-Beam and a Super-Beam facility

In this letter we present the study of the eightfold degeneracy in the $(θ_{13},δ)$ measurement including both appearance and disappearance channels. We analyse, for definiteness, the case of a standard low-$γ$ $β$-Beam and a 4 MWatt SPL Super-Beam facility, both aiming at a UNO-like Mton water Cerenkov detector located at the Frejus laboratory, $L = 130$ km. In the $β$-Beam case, the \nue disappearance channel does not improve the $(θ_{13},δ)$ measurement when a realistic (i.e. $\ge$ 2%) systematic error is included. In the Super-Beam case, the \numu disappearance channel could, instead, be quite useful in reducing the impact of the eightfold degeneracy in the $(θ_{13},δ)$ measurement, especially once the error on the atmospheric mass difference is fully taken into account in the fit.

hep-ph↗
arXiv2004

Study of the eightfold degeneracy with a standard $β$-Beam and a Super-Beam facility

The study of the eightfold degeneracy at a neutrino complex that includes a standard $β$-Beam and a Super-Beam facility is presented for the first time in this paper. The scenario where the neutrinos are sent toward a Megaton water Cerenkov detector located at the Fréjus laboratory (baseline 130 Km) is exploited. The performance in terms of sensitivity for measuring the continuous ($θ_{13}$ and $δ$) and discrete (${sign} [ Δm^2_{23} ]$ and ${sign} [\tan (2θ_{23}) ]$) oscillation parameters for the $β$-Beam and Super-Beam alone, and for their combination has been studied. A brief review of the present uncertainties on the neutrino and antineutrino cross-sections is also reported and their impact on the discovery potential discussed.

hep-ph↗
arXiv2003

Clone flow analysis for a theory inspired Neutrino Experiment planning

The presence of several clone solutions in the simultaneous measurement of ($θ_{13},δ$) has been widely discussed in literature. In this letter we write the analytical formulae of the clones location in the ($θ_{13},δ$) plane as a function of the physical input pair ($\barθ_{13},\barδ$). We show how the clones move with changing $\barθ_{13}$. The "clone flow" can be significantly different if computed (naively) from the oscillation probabilities or (exactly) from the probabilities integrated over the neutrino flux and cross-section. Using our complete computation we compare the clone flow of a set of possible future neutrino experiments: the CERN SuperBeam, BetaBeam and Neutrino Factory proposals. We show that the combination of these specific BetaBeam and SuperBeam does not help in solving the degeneracies. On the contrary, the combination of one of them with the Neutrino Factory Golden and Silver channel can be used, from a theoretical point of view, to solve completely the eightfold degeneracy.

hep-ph↗
arXiv2003

NUFACT'03: The Fate of the Clones

We present a Neutrino-Factory-based setup with three detectors of different kind in principle capable to solve the eightfold-degeneracy in the simultaneous measurement of $θ_{13}$ and $δ$, for $θ_{13} \geq 1^\circ (\sin^2 (2 θ_{13}) \geq 10^{-3})$. Our setup includes a Superbeam-driven water Cherenkov (the Superbeam conceived as the first stage of the Neutrino Factory); two muon-storage-ring-driven detectors (namely, a large magnetized iron calorimeter and an emulsion cloud chamber) to take advantage of both the so-called "golden" ($ν_e \to ν_μ$) and "silver" ($ν_e \to ν_τ$) channels.

hep-ph↗
arXiv2003

Using nu_e -> nu_tau: golden and silver channels at the Neutrino Factory

I briefly review the source of the so-called intrinsic ambiguity and show how the combination of ``golden'' and ``silver'' channel at the Neutrino Factory can solve the problem, in the absence of other sources of degeneracies. I then relaxed the hypothesis $θ_{23} = 45^\circ$ and show how the different dependence of the two channels on $θ_{23}$ can help in solving the intrinsic and $θ_{23}$-octant ambiguity at the same time.

hep-ph↗
arXiv2003

The synergy of the golden and silver channels at the Neutrino Factory

We deepen the study of the so-called ``silver channel'' $ν_e \to ν_τ$ \cite{Donini:2002rm} and of its relevance to solve some of the ambiguities that can arise in the simultaneous measurement of $(θ_{13},δ)$ at the Neutrino Factory by presenting in full detail the characteristics of the considered OPERA-like detector and the experimental treatment of the different backgrounds and signals. Furthermore, we perform a detailed study of the systematic errors associated both with the OPERA-like and the magnetized-iron detectors and their effects on the sensitivity. Finally, we also apply a refined statistical analysis of the simulated events based on the frequentist approach.

hep-ph↗
arXiv2002

O.P.E. and Power Corrections to the QCD coupling constant

Lattice data seems to show that power corrections should be convoked to describe appropriately the transition of the QCD coupling constant running from U.V. to I.R. domains. Those power corrections for the Landau-gauge MOM coupling constant in a pure Yang-Mills theory (N_f=0) are analysed in terms of Operator Product Expansion (O.P.E.) of two- and three-point Green functions, the gluon condensate emerging from this study. The semi-classical picture given by instantons can be also used to look for into the nature of the power corrections and gluon condensate.

hep-ph↗
arXiv2002

An Instanton Picture O.P.E. Condensate?

Gluon two- and three-point Green Functions computed in Landau gauge from the lattice show the existence of power corrections to the purely perturbative expressions, that can be explained through an Operator Product Expansion as the influence of a non gauge invariant mass dimension two condensate. The relationship of this condensate with topological properties of QCD, namely instantons, will be studied, giving a first estimate of the contribution of instantons to this condensate based in the direct lattice measure, after a cooling process, of the instanton liquid properties.

hep-ph↗
arXiv2002

Instantons and $ $ Condensate

We argue that the $ $ condensate found in the Landau gauge on lattices, when an Operator Product Expansion of Green functions is performed, might be explained by instantons. We use cooling to estimate the instanton contribution and extrapolate back the result to the thermalised configuration. The resulting $ $ is similar to $ $.

hep-ph↗
arXiv2002

The silver channel at the Neutrino Factory

We notice that looking for $ν_e \to ν_τ$ at the same time as $ν_e \to ν_μ$ oscillations could significantly help to reduce the errors in the leptonic CP-violating phase $δ$ measurement. We show how the $ν_e \to ν_μ$ (``golden'') and $ν_e \to ν_τ$ (``silver'') transitions observed at an OPERA-like 2 Kton lead-emulsion detector at L = 732 Km, in combination with the $ν_e \to ν_μ$ transitions observed at a 40 Kton magnetized iron detector with a baseline of L = 3000 Km, strongly reduce the so-called $(θ_{13}, δ)$ ambiguity. We also show how a moderate increase in the OPERA-like detector mass (4 Kton instead of 2 Kton) completely eliminates the clone regions even for small values of $θ_{13}$.

hep-ph↗
arXiv2002

OPE and Powers corrections on the QCD coupling constant

The running coupling constant can be estimated by computing gluon two- and three-point Green functions from the lattice. Computing in lattice implies working in a fixed gauge sector (Landau). An source of systematic uncertainty is then the contribution of non gauge-invariant condensates, as $ $, generating power corrections that might still be important at very high energies. We study the impact of this gluon condensate on the analysis of gluon propagator and vertex lattice data and on the estimate of $Λ_{\bar{\rm MS}}$. We finally try a qualitative description of this gluon condensate through the instanton picture

hep-ph↗
arXiv2001

Telling three from four neutrinos at the Neutrino Factory

We upgrade the study of the physical reach of a Neutrino Factory considering the possibility to distinguish a three (active) neutrino oscillation scenario from the scenario in which a light sterile neutrino is also present. The distinction is easily performed in the so--called 2+2 scheme, but also in the more problematic 3+1 scheme it can be attained in some regions of the parameter space. We also discuss the CP violating phase determination, showing that the effects of a large phase in the three--neutrino theory cannot be reproduced in a four--neutrino, CP conserving, model.

hep-ph↗