Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
54,679
result(s) for
"Neutrinos."
Sort by:
Superluminal neutrinos: an OPERA in three acts
In September 2011 the OPERA experiment at the Gran Sasso Laboratory, Italy announced that they had evidence that the neutrinos in the CERN-to-Gran-Sasso (CNGS) beam line were travelling very slightly faster than the speed of light. If true this would have ranked among the most important discoveries of the 21st century. In the event it was not true and was rapidly discredited. This paper explains what the measurement entailed, the responses to it and the eventual explanation, and discusses whether the initial publication and the subsequent reactions were appropriate.
Journal Article
Revisiting the A4 model for leptons in light of NuFIT 3.2
We revisit the $A_4$ model for leptons in light of the new result of NuFIT 3.2. We introduce a new flavon $\\eta$ transforming as an $A_4$ singlet $1'$ or $1''$, which couples to both charged leptons and neutrinos in next-to-leading-order operators. The model consists of five parameters: the lightest neutrino mass $m_1$, the vacuum expectation value of $\\eta$, and three CP-violating phases after inputting the experimental values of $\\Delta m_{\\rm atm}^2$ and $\\Delta m_{\\rm sol}^2$. The model with the $1''$ singlet flavon gives the prediction of $\\sin^2 \\theta_{12}$ around the best fit of NuFIT 3.2 while staying near the maximal mixing of $\\theta_{23}$. Inputting the experimental mixing angles with the $1\\,\\sigma$ error-bar, the Dirac CP-violating phase is clearly predicted to be $|\\delta_\\text{CP}|=50$–$120^\\circ$, which will be tested by the precise observed value in the future. In order to get the best-fit value $\\sin^2\\theta_{23}=0.538$, the sum of three neutrino masses is predicted to be larger than $90$meV. The cosmological observation for the sum of the neutrino masses will also provide a crucial test of our predictions. It is remarked that the model is consistent with the experimental data only for the normal hierarchy of neutrino masses.
Journal Article
Neutrino
Discusses the development of the theory of the existence of neutrinos, and examines the struggle to detect and understand the tiny particles.
Book
Results and Perspectives from the First Two Years of Neutrino Physics at the LHC by the SND@LHC Experiment
After rapid approval and installation, the SND@LHC Collaboration was able to gather data successfully in 2022 and 2023. Neutrino interactions from νμs originating at the LHC IP1 were observed. Since muons constitute the major background for neutrino interactions, the muon flux entering the acceptance was also measured. To improve the rejection power of the detector and to increase the fiducial volume, a third Veto plane was recently installed. The energy resolution of the calorimeter system was measured in a test beam. This will help with the identification of νe interactions that can be used to probe charm production in the pseudo-rapidity range of SND@LHC (7.2 < η < 8.4). Events with three outgoing muons have been observed and are being studied. With no vertex in the target, these events are very likely from muon trident production in the rock before the detector. Events with a vertex in the detector could be from trident production, photon conversion, or positron annihilation. To enhance SND@LHC’s physics case, an upgrade is planned for HL-LHC that will increase the statistics and reduce the systematics. The installation of a magnet will allow the separation of νμ from ν¯μ
Journal Article
Contribution of heavy neutrinos to decay of standard-model-like Higgs boson →μτ in a 3-3-1 model with additional gauge singlets
Abstract
In the framework of the improved version of the 3-3-1 models with right-handed neutrinos, which are added to the Majorana neutrinos as new gauge singlets, the recent experimental neutrino oscillation data is completely explained through the inverse seesaw mechanism. We show that the major contributions to $Br(\\mu\\rightarrow e\\gamma)$ are derived from corrections at one-loop order of heavy neutrinos and bosons. But, these contributions are sometimes mutually destructive, creating regions of parametric spaces where the experimental limits of $Br(\\mu\\rightarrow e\\gamma)$ are satisfied. In these regions, we find that $Br(\\tau\\rightarrow \\mu\\gamma)$ can achieve values of $10 ^{- 10}$ and $Br(\\tau\\rightarrow e\\gamma)$ may even reach values of $10 ^{- 9}$, very close to the upper bound of the current experimental limits. Those are ideal areas to study lepton-flavor-violating decays of the standard-model-like Higgs boson ($h_1^0$). We also point out that the contributions of heavy neutrinos play an important role in changing $Br(h_1^0\\rightarrow \\mu\\tau)$; this is presented through different forms of mass mixing matrices ($M_R$) of heavy neutrinos. When $M_R \\sim \\mathrm{diag}(1,1,1)$, $Br(h_1^0\\rightarrow \\mu\\tau)$ can attain a greater value than in the cases $M_R \\sim \\mathrm{diag}(1,2,3)$ and $M_R \\sim \\mathrm{diag}(3,2,1)$; the largest that $Br(h_1^0\\rightarrow \\mu\\tau)$ can reach is very close $10 ^{-3}$.
Journal Article
Double Chooz θ13 measurement via total neutron capture detection
Neutrinos were assumed to be massless particles until the discovery of the neutrino oscillation process. This phenomenon indicates that the neutrinos have non-zero masses and the mass eigenstates (
ν
1
,
ν
2
,
ν
3
) are mixtures of their flavour eigenstates (
ν
e
,
ν
μ
,
ν
τ
). The oscillations between different flavour eigenstates are described by three mixing angles (
θ
12
,
θ
23
,
θ
13
), two differences of the squared neutrino masses of the
ν
2
/
ν
1
and
ν
3
/
ν
1
pairs and a charge conjugation parity symmetry violating phase
δ
CP
. The Double Chooz experiment, located near the Chooz Electricité de France reactors, measures the oscillation parameter
θ
13
using reactor neutrinos. Here, the Double Chooz collaboration reports the measurement of the mixing angle
θ
13
with the new total neutron capture detection technique from the full data set, yielding sin
2
(2
θ
13
) = 0.105 ± 0.014. This measurement exploits the multidetector configuration, the isoflux baseline and data recorded when the reactors were switched off. In addition to the neutrino mixing angle measurement, Double Chooz provides a precise measurement of the reactor neutrino flux, given by the mean cross-section per fission 〈
σ
f
〉 = (5.71 ± 0.06) × 10
−43
cm
2
per fission, and reports an empirical model of the distortion in the reactor neutrino spectrum.
The Double Chooz collaboration reports the neutrino oscillation parameter
θ
13
from a measurement of the disappearance of reactor anti-electron neutrinos with the total neutron capture technique.
Journal Article