构建LMA-Dark解决方案的中微子大非标准相互作用模型

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"中微子的大型非标准相互作用的模型，导致LMA-Dark解决方案" 在粒子物理学领域，中微子是一种基本粒子，其性质和行为一直是科学家们探索的重要课题。标准模型，即我们理解的基本粒子和力的框架，虽然在许多方面取得了成功，但在解释某些中微子现象时却存在局限性。其中一个未解之谜是太阳中微子问题，这个问题催生了两种主要的解决方案：标准的LMA（Large Mixing Angle）解决方案和LMA-Dark解决方案。 LMA-Dark解决方案提出了一种非标准相互作用（NSI）的概念，这种相互作用的强度与费米耦合相当，即与弱相互作用的强度相比较。NSI允许中微子与普通物质以非标准方式相互作用，这可能解释了低能量太阳中微子的观测结果。然而，由于缺乏一个与现有实验约束相兼容的模型，LMA-Dark方案并未被广泛接受。本文介绍了一个新的物理模型，旨在为LMA-Dark解决方案提供理论基础。该模型基于一个新的U（1）'规范群，其中包含一个质量约为10 MeV的质量玻色子。这个新粒子使得第二代和第三代轻子以及夸克带有电荷，从而引入了非标准的中微子相互作用。这样的设置使得NSI的强度和口味结构得以合理化，符合LMA-Dark解决方案的需求。模型的预言包括在超新星和高能宇宙中微子的光谱中可能出现的可观测效应。超新星中微子的探测对于理解恒星爆炸过程至关重要，而高能宇宙中微子则可能揭示宇宙深处的极端环境。此外，该模型还预测了介子磁偶极矩的新贡献，这是一个尚未被观测到但理论上重要的物理量。同时，模型还预言了新的稀有介子衰变模式，这些衰变模式如果被观测到，将为检验模型提供直接证据。这篇论文提出的模型为理解太阳中微子问题提供了一个新的视角，特别是在LMA-Dark解决方案中引入的大型非标准相互作用。这一理论不仅解决了现有观测数据的匹配问题，还预测了一些可测试的物理效应，为未来的实验研究开辟了新的途径。然而，要完全验证这个模型，需要进一步的理论发展和更加精确的实验测量。

Physics Letters B 748 (2015) 311–315

Contents lists available at ScienceDirect

Physics Letters B

www.elsevier.com/locate/physletb

A model for large non-standard interactions of neutrinos leading to

the LMA-Dark solution

Yasaman Farzan

School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran

a r t i c l e i n f o a b s t r a c t

Article history:

Received

7 June 2015

Accepted

8 July 2015

Available

online 13 July 2015

Editor:

G.F. Giudice

It is well-known that in addition to the standard LMA solution to solar anomaly, there is another solution

called LMA-Dark which requires Non-Standard Interactions (NSI) with effective couplings as large as

the Fermi coupling. Although this solution satisﬁes all the bounds from various neutrino oscillation

observations and even provides a better ﬁt to low energy solar neutrino spectrum, it is not as popular

as the LMA solution mainly because no model compatible with the existing bounds has been so far

constructed to give rise to this solution. We introduce a model that provides a foundation for such

large NSI with strength and ﬂavor structure required for the LMA-Dark solution. This model is based

on anew U (1)



gauge interaction with a gauge boson of mass ∼ 10 MeV under which quarks as well as

the second and third generations of leptons are charged. We show that observable effects can appear in

the spectrum of supernova and high energy cosmic neutrinos. Our model predicts a new contribution to

the muon magnetic dipole moment and new rare meson decay modes.

(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP

1. Introduction

Three neutrino mass and mixing scheme has been established

as the standard solution to the solar and atmospheric neutrino

anomalies. In general, the implicit assumption is that the alter-

native

solutions to these anomalies (e.g., the magnetic transition

moment of neutrinos) are now ruled out and can at most pro-

vide

only a subdominant effect yet to be resolved. However, the

so-called LMA-Dark solution, which is based on relatively large

non-standard neutral current interactions of neutrinos with mat-

ter ,

is an exception that deﬁes this general assumption.

Surprisingly,

the LMA-Dark solution not only passes all the

bounds from various neutrino oscillation experiments but is also

considered as one of the solutions for the suppression of the up-

turn

on low energy spectrum of solar neutrinos which is in a mild

tension with the standard neutrino oscillation scenario [1]. In other

words, the compatibility of LMA-Dark solution with the neutrino

data is even better than the standard three neutrino oscillation

scheme without Non-Standard Interaction (NSI). The reason for this

solution staying in the shadow of the LMA solution is mostly theo-

retical.

In fact, there is no shortage of beyond standard models that

give rise to NSI of neutrinos with matter [2,3]. The ratio of new

effects within beyond Standard Model (SM) scenarios on forward

E-mail address: yasaman@theory.ipm.ac.ir.

scattering amplitude of neutrinos on matter to the SM contribu-

tion

is expected to be given by (g

−2

)/G

, where g

and m

are respectively the coupling and mass of the new particle whose

exchange leads to an effective four-Fermi interaction between neu-

trinos

and matter ﬁeld. Taking m

 m

to avoid bounds from

direct collider searches of new particles and requiring g

to be

relatively small to remain in the perturbative region, we ﬁnd that

the NSI effects are suppressed relative to the standard model ef-

fects.

For the LMA-Dark solution, the NSI effects should be as large

as the standard ones. Thus, in the framework of beyond standard

models with heavy particles (m

 m

), there is no theoretical

basis for the LMA-Dark solution. The purpose of this letter is to

build a model or a class of models that provide such a basis.

The

model presented here is based on a new U (1) gauge inter-

action

with a gauge boson of mass m



∼ few 10 MeV and gauge

coupling of g



∼ 10

−5

which couples to the second and third

generations of leptons (but not to the electron) as well as to the

quarks. This gauge interaction leads to effective four-Fermi interac-

tions

with form and coupling strength required for the LMA-Dark

solution. We expect new observable effects on the muon magnetic

dipole moment, supernova evolution, trident neutrino production,

meson decays and the spectrum of high energy cosmic neutrinos

[4,5]. As shown in [6], such a model can be tested by studying

μ + A →μ + A + Z



where A is a nucleus.

The

letter is organized as follows: In Section 2, the LMA-Dark

solution is brieﬂy reviewed. In Section 3, the model is presented.

http://dx.doi.org/10.1016/j.physletb.2015.07.015

0370-2693/

SCOAP

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