LHC Run II 数据揭示非标准中微子相互作用的新限制

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"在LHC Run II中探查非标准中微子相互作用" 这篇论文主要探讨了在大型强子对撞机（LHC）的第二运行阶段（Run II）中，如何通过寻找非标准中微子相互作用来探索超越标准模型的物理学新领域。非标准中微子相互作用是指那些超出目前标准模型框架、可能揭示新物理现象的中微子与其它粒子之间的相互作用。这些相互作用可以提供关于宇宙中未知力量或基本粒子性质的重要线索。标准模型是粒子物理学的基础理论，它成功地描述了所有已知的基本粒子以及它们之间的大部分相互作用，但无法解释一些观测到的现象，比如暗物质和中微子质量。因此，科学家一直在寻找标准模型之外的新物理现象。论文中提到的“轻子B衰变的异常”可能指的是B介子（一种由一个夸克和一个反夸克组成的重粒子）的不寻常衰变模式，这些模式在统计上与标准模型的预测存在偏差。这些异常可能暗示着新的粒子或作用力的存在，而中微子的非标准相互作用可能是其中的一种解释。作者Debajyoti Choudhury、Kirtiman Ghosh和Saurabh Niyogi分析了LHC Run II的数据，该数据集包含了大量高能粒子碰撞事件。他们发现，这些数据已经排除了许多专用中微子实验所期望探测到的非标准中微子相互作用的参数空间。这意味着，尽管LHC并非专门设计用于中微子实验，但它在寻找新物理信号方面提供了有力的补充。 LHC Run II的数据分析结果对未来的中微子实验具有重要指导意义，因为它们限制了可能的非标准相互作用的范围，有助于指导实验设计和预期。同时，这也强调了跨领域的合作和不同实验类型之间的互补性，对于推进粒子物理学前沿研究至关重要。在粒子物理学的探索过程中，每一步都可能带来新的突破。通过在LHC Run II中排除非标准中微子相互作用的某些可能性，研究人员能够更精确地聚焦于可能隐藏新物理现象的其他区域，从而推动我们对宇宙的理解更进一步。

Physics Letters B 784 (2018) 248–254

Contents lists available at ScienceDirect

Physics Letters B

www.elsevier.com/locate/physletb

Probing nonstandard neutrino interactions at the LHC Run II

Debajyoti Choudhury

, Kirtiman Ghosh

b,c,∗

, Saurabh Niyogi

Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India

Institute of Physics, Bhubaneswar 751005, India

HBNI, Mumbai, India

Department of Physics, Gokhale Memorial Girls’ College, Harish Mukherjee Road, Kolkata 700020, India

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

Article history:

Received

29 March 2018

Received

in revised form 16 July 2018

Accepted

29 July 2018

Available

online 14 August 2018

Editor:

A. Ringwald

Searching for non-standard neutrino interactions, as a means for discovering physics beyond the Standard

Model, has been one of the key goals of dedicated neutrino experiments, current and future. This has

received recent ﬁllip in the wake of reported anomalies in leptonic B-decays. We demonstrate here that

much of the parameter space accessible to such dedicated neutrino experiments is already ruled out by

the RUN II data of the Large Hadron Collider experiment.

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

1. Introduction

Precision measurements of the neutrino mixing parameters,

made over the past few decades has signiﬁcantly shortened the

list of unanswered questions in the standard scenario to just the

issues of the neutrino mass hierarchy i.e., sign(δm

), the CP phase

and the correct octant for the mixing angle θ

. While the simplest

way to generate neutrino masses is to add right handed neutrino

ﬁelds to the Standard Model (SM) particle content, it is hard to

explain the extreme smallness of the said masses. Several scenar-

ios

going beyond the SM have been proposed to this end, often

tying up with other unanswered questions such as (electroweak)

leptogenesis [1,2], neutrino magnetic moments [3–6], and even

dark energy [7,8](by invoking neutrino condensates). An agnos-

tic

alternative is to add dimension-ﬁve terms consistent with the

symmetries and particle content of the SM, which naturally leads

to desired tiny Majorana masses for the left-handed neutrinos. Ir-

respective

of the approach, once new physics is invoked to explain

the non-zero neutrino masses, it is unnatural to exclude the pos-

sibility

of non-standard interactions (NSI) as well. Indeed, NSI has

been studied in the context of atmospheric neutrinos [9–14], CPT

violation [15,16], violation of the equivalence principle [13], large

extra dimension models [17], sterile neutrinos [18–20] and collider

experiments [21–24].

Corresponding author.

E-mail

addresses: debajyoti.choudhury@gmail.com (D. Choudhury),

kirti.gh@gmail.com (K. Ghosh), saurabhphys@gmail.com (S. Niyogi).

While no incontrovertible evidence for such NSI exists, certain

anomalies in leptonic B-decays [25–30], together, strongly indicate

a new physics scale of a few TeVs [31]. Not only is the existence of

analogous neutrino-NSI conceivable, there exist theoretically well-

motivated

scenarios wherein NSI would manifest primarily in the

neutrino sector (e.g., those referred to earlier). Consequently, the

search of NSI constitutes a major stated goal of neutrino experi-

ments.

We demonstrate, in this letter, that much of the parameter

space that such a future dedicated neutrino experiment would be

sensitive to, can already be ruled out by an analysis of the LHC

data.

suﬃciently low energies, a wide class of new physics sce-

narios

can be parametrized, in a model independent way, through

the use of effective four-fermion interaction terms.

The investiga-

tion

of these assumes further importance as the aforementioned

anomalies in B-decays are quite well-explained on the introduc-

tion

of such terms [31]. While these, in general, would incorporate

both charged-current (CC) and neutral-current (NC) interactions,

we shall conﬁne ourselves largely to the latter (coming back to

the former only later). The dimension-6 neutrino-quark interac-

tions

can, then, be expressed, in terms of the chirality projection

operators P

(X = L, R), as

=−2

√

2 G



αβ



qγ





H.c., (1)

The obvious caveat is the situation where the NSI is occasioned by a light (well

below the weak scale) mediator [32–34]. Not only do such models need ultrasmall

fermionic couplings, the model-dependence is extreme and no uniﬁed treatment is

possible. Hence we shall eschew a discussion of the same.

https://doi.org/10.1016/j.physletb.2018.07.053

0370-2693/

SCOAP

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