Constraining Neutrinoless Double-Beta Decay Matrix Elements from Ab Initio Nuclear Theory A. Belley1 2 aT. Miyagi3 4S. R. Stroberg5 band J. D. Holt1 6

2025-04-27 0 0 324.09KB 4 页 10玖币

侵权投诉

Constraining Neutrinoless Double-Beta Decay Matrix Elements

from Ab Initio Nuclear Theory

A. Belley,1, 2, a) T. Miyagi,3, 4 S. R. Stroberg,5, b) and J. D. Holt1, 6

1)TRIUMF, 4004 Wesbrook Mall, Vancouver BC V6T 2A3, Canada

2)Department of Physics & Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada

3)Technische Universität Darmstadt, Department of Physics, 64289 Darmstadt, Germany

4)ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany

5)Physics Division, Argonne National Laboratory, Lemont, IL, 60439, USA

6)Department of Physics, McGill University, Montréal, QC H3A 2T8, Canada

a)Corresponding author: abelley@triumf.ca

b)Current address: Department of Physics and Astronomy, University of Notre Dame, Notre Dame, IN, 46556, USA

Abstract. As experimental searches for neutrinoless double-beta (0νβ β ) decay are entering a new generation, with hopes to

completely probe the inverted mass hierarchy, the need for reliable nuclear matrix elements, which govern the rate of this decay,

is stronger than ever. Since a large discrepancy in results is typically found with nuclear models [1], a large unknown still exists

on the sensitivity of these experiments to the effective neutrino mass. We consider this problem from a ﬁrst-principles perspective,

using the ab initio valence-space in medium similarity renormalization group. In particular, we study correlations of the 0νβ β -

decay matrix elements in 76Ge with other observables, such as the double Gamow-Teller giant resonance, from 34 input chiral

interactions in an attempt to constrain our uncertainties and investigate the interaction dependence of the nuclear matrix element.

INTRODUCTION

The observation of neutrinoless double-beta (0νβ β ) decay, a hypothetical process in which two neutrons transform

into two protons without emitting an antineutrino, would show that lepton number is not a conserved quantity, thus

having important implications for the matter-antimatter asymmetry puzzle [2]. As the nuclear matrix element (NME)

of this decay is intrinsically related to its half-life, a reliable way of obtaining the NME of this transition with asso-

ciated theoretical uncertainty is of crucial importance in order to compare experimental limits in different isotopes,

pinpoint the mechanism responsible for lepton number violation, and extract key quantities such as the absolute mass

scale of the neutrino upon potential observation of the process [1, 3, 4]. Ab initio nuclear theory offers an unpar-

alleled tool to tackle the challenging task of computing the nuclear matrix elements, as it is based on systematically

improvable methods that allow for rigorous uncertainty quantiﬁcation [5]. In these ﬁrst-principle methods, the nuclear

Hamiltonian is constructed from two- (NN) and three-nucleon (3N) forces obtained from chiral effective ﬁeld theory

(EFT) and the time-independent Schrödinger equation is then solved using nonperturbative many-body methods.

Chiral EFT offers a systematic expansion of nuclear and electroweak forces involved in this decay, while encoding

neglected higher-energy information in contact terms, whose low-energy constants (LECs) are ﬁt to reproduce chosen

experimental data [6, 7]. In this work, the valence-space in-medium similarity renormalization group (VS-IMSRG) [8,

9, 10, 11] is used to approximately solve the Schrödinger equation and obtain NMEs from different starting chiral

EFT potentials. This method decouples an effective valence-space Hamiltonian from the full space via continuous

unitary transformations, therefore (in the absence of many-body truncations) preserving the eigenstates of the original

Hamiltonian, while reducing signiﬁcantly the size of the space considered. The valence-space Hamiltonian is then

diagonalized using the shell-model code KSHELL [12], thereby extending the reach of ab initio calculations to that

of the traditional shell model [13]. Operators are then evolved using the same unitary transformations, allowing them

to be treated consistently with the Hamiltonian. To make the problem computationally tractable, all operators are

truncated at the normal-ordered two-body level, introducing the primary many-body approximation, IMSRG(2), in

the NMEs. We further restrict the size of the initial single-particle space following the emax truncation, which limits

the possible state to those having e=2n+l≤emax where nis the principal quantum number and lis the orbital angular

momentum. Finally, 3N forces are truncated via e1+e2+e3≤E3max to satisfy computational memory limitations.

Until recently, the E3max truncation proved to be the key bottleneck for ab initio methods to reach the heavy isotopes

of experimental relevance for 0νβ β . Fortunately, recent advances [14] have overcome this limitation, allowing for

the ﬁrst ab initio NMEs for 130Te and 136Xe [15], two of the most predominant candidates for experimental searches,

joining previous calculations for 48Ca [16, 17, 18], as well as 76Ge, and 82Se [17].

arXiv:2210.05809v1 [nucl-th] 11 Oct 2022

文档加载中……请稍候！
如果长时间未打开，您也可以点击刷新试试。

下载文档到电脑，查找使用更方便

10 玖币 0人已下载

立即下载

摘要：

ConstrainingNeutrinolessDouble-BetaDecayMatrixElementsfromAbInitioNuclearTheoryA.Belley,1,2,a)T.Miyagi,3,4S.R.Stroberg,5,b)andJ.D.Holt1,61)TRIUMF,4004WesbrookMall,VancouverBCV6T2A3,Canada2)DepartmentofPhysics&Astronomy,UniversityofBritishColumbia,Vancouver,BritishColumbiaV6T1Z1,Canada3)TechnischeUni...

展开>> 收起<<

Constraining Neutrinoless Double-Beta Decay Matrix Elements from Ab Initio Nuclear Theory A. Belley1 2 aT. Miyagi3 4S. R. Stroberg5 band J. D. Holt1 6.pdf

共4页,预览1页

还剩页未读，继续阅读

声明：本站为文档C2C交易模式，即用户上传的文档直接被用户下载，本站只是中间服务平台，本站所有文档下载所得的收益归上传人(含作者)所有。玖贝云文库仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对上载内容本身不做任何修改或编辑。若文档所含内容侵犯了您的版权或隐私，请立即通知玖贝云文库，我们立即给予删除！

Constraining Neutrinoless Double-Beta Decay Matrix Elements from Ab Initio Nuclear Theory A. Belley1 2 aT. Miyagi3 4S. R. Stroberg5 band J. D. Holt1 6

相关推荐

开通VIP享超值会员特权

作者详情

相关内容

热门标签

举报选择: