KM3NeT-ORCA探测新途径：揭示可见中微子隐秘衰减
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在"用KM3NeT-ORCA约束看不见的中微子衰变"这篇论文中，作者探讨了标准模型外的粒子物理理论对中微子行为的新假说。中微子，作为基本粒子，其衰变在标准模型框架下并不被预测，但超出此模型的一些理论提出中微子可能存在非标准的衰变路径。论文假设中微子的振荡过程受到改变，特别是最重的质量态可能会通过转化为无味中微子（sterile neutrino）的方式衰减，这一过程可能由标量或马洛顿效应驱动。
论文的核心焦点在于利用即将进行的KM3NeT-ORCA实验来测试这一假设。KM3NeT-ORCA是深海中微子观测项目的一部分，它通过探测来自宇宙的高能中微子，旨在深入理解基本粒子的行为。在这个实验背景下，作者分析了该实验对于探索这种潜在衰变模式的敏感性，指出这将使当前基于三中微子振荡的实验限制得以显著提升，可能达到现有范围的两倍左右。
此外，论文还讨论了中微子衰变对已知的中微子物理参数如大气振荡参数sin²θ23和Δm312的影响。大气振荡是指中微子在穿越地球大气层时能量和类型的变化，这两个参数在中微子物理学中至关重要。如果存在中微子衰变，这些参数的测量可能会出现偏差，从而影响我们对中微子性质和宇宙早期历史的理解。
中微子质量排序，即三种不同中微子类型的相对质量，也是研究的重要方面。中微子质量的了解对于揭示宇宙的起源和演化具有重要意义，因此，任何关于中微子衰变的新发现都可能重新定义我们对这一领域的认识。
本文的工作不仅扩展了我们对中微子行为的认知边界，还展示了通过现代实验技术，如KM3NeT-ORCA，可以如何深化对基本粒子物理的探索。这篇开放获取的研究成果对于粒子物理学家来说是一个重要的里程碑，它预示着未来可能会揭示中微子世界的更多奥秘。
Physics Letters B 789 (2019) 472–479
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Constraining the invisible neutrino decay with KM3NeT-ORCA
P.F. de Salas
a,b
, S. Pastor
a,∗
, C.A. Ternes
a
, T. Thakore
a
, M. Tórtola
a
a
Institut de Física Corpuscular (CSIC – Universitat de València), Parc Cientific de la UV, C/ Catedratico José Beltrán, 2, E-46980 Paterna (València), Spain
b
The Oskar Klein Centre for Cosmoparticle Physics, Department of Physics, Stockholm University, SE-106 91 Stockholm, Sweden
a r t i c l e i n f o a b s t r a c t
Article history:
Received
5 November 2018
Received
in revised form 17 December 2018
Accepted
27 December 2018
Available
online 3 January 2019
Editor:
A. Ringwald
Keywords:
Neutrino
masses and mixing
Neutrino
oscillations
Neutrino
decay
Neutrino
telescopes
Several theories of particle physics beyond the Standard Model consider that neutrinos can decay. In
this work we assume that the standard mechanism of neutrino oscillations is altered by the decay of
the heaviest neutrino mass state into a sterile neutrino and, depending on the model, a scalar or a
Majoron. We study the sensitivity of the forthcoming KM3NeT-ORCA experiment to this scenario and
find that it could improve the current bounds coming from oscillation experiments, where three-neutrino
oscillations have been considered, by roughly two orders of magnitude. We also study how the presence
of this neutrino decay can affect the determination of the atmospheric oscillation parameters sin
2
θ
23
and
m
2
31
, as well as the sensitivity to the neutrino mass ordering.
© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
1. Introduction
Over the last two decades or so, we have found overwhelming
evidence for oscillating neutrinos. The oscillatory behavior can be
described in terms of six parameters: the solar and atmospheric
mass splittings m
2
21
and m
2
31
, the solar angle θ
12
, the atmo-
spheric
angle θ
23
, the reactor angle θ
13
and the CP phase δ. These
parameters have been measured in solar, reactor, atmospheric
and long-baseline accelerator neutrino oscillation experiments. The
level of precision reached by current experiments is such that,
from the global picture [1–5], neutrino oscillation physics is en-
tering
the precision era. However, there are still some unknowns
to be established:
1. The
true ordering of neutrino masses: we still do not know
if the order of the neutrino mass spectrum is normal (NO),
where m
3
is the heaviest mass state, or inverted (IO), where
m
2
is the heaviest one. Recent oscillation results show a pref-
erence
for NO [1,2], although the real neutrino mass ordering
is not fully determined yet [6].
2. The
octant of the atmospheric angle: the measured value of
sin
2
θ
23
is close to maximal (0.5), but it can be either smaller
(lower octant) or larger (upper octant).
*
Corresponding author.
E-mail
addresses: pabferde@ific.uv.es (P.F. de Salas), pastor@ific.uv.es (S. Pastor),
chternes@ific.uv.es (C.A. Ternes), tarak.thakore@ific.uv.es (T. Thakore),
mariam@ific.uv.es (M. Tórtola).
3. The exact value of the CP phase δ: values of δ ≈ 0.5π are now
highly disfavored, but still a large part of the parameter space
remains allowed. At 2σ confidence level, CP might be maxi-
mally
violated, but also conserved.
4. The
absolute scale of neutrino masses: so far there are only
upper bounds on it, coming from beta decay experiments and
cosmological measurements [7].
5. The
nature of neutrinos: are they Dirac or Majorana particles?
In the latter case, there are two extra CP phases to be deter-
mined,
which are only accessible through neutrinoless double
beta decay experiments (see e.g. [8]).
The
last two points can not be determined by neutrino oscillation
experiments, since flavor oscillations are insensitive to the abso-
lute
neutrino masses and to the Majorana CP phases. Conversely,
the three first issues are expected to be solved by the future long-
baseline
experiment DUNE, which will measure very well the mass
ordering [9]as well as the value of the CP-violating phase and the
octant of the atmospheric mixing angle [10]within the standard
three-neutrino picture.
The
determination of the mass ordering of neutrinos is also one
of the main physics goals of the future atmospheric experiment
ORCA (Oscillation Research with Cosmics in the Abyss) [11], that
will provide precise measurements of the atmospheric parameters
too. ORCA will be basically an updated version of the ANTARES
neutrino telescope, with a denser instrumented setup: 115 lines
with 9 m spacing between the Digital Optical Modules (DOMs) and
20 m horizontal spacing between the detector lines. This will result
in an energy threshold of only a few GeV, enhancing its sensitivity
https://doi.org/10.1016/j.physletb.2018.12.066
0370-2693/
© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.
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