{"title":"Emergent large flavor mixing from canonical and inverse seesaws?","authors":"Zhi-zhong Xing","doi":"10.1016/j.nuclphysb.2025.116853","DOIUrl":null,"url":null,"abstract":"<div><div>While the canonical seesaw mechanism provides a most natural <em>qualitative</em> interpretation of tiny masses for the three active neutrinos, it offers no explanation for their large flavor mixing effects. The latter can be regarded as an <em>emergent</em> consequence of this mechanism, in which case we are left with an intriguing <em>cross seesaw</em> framework in the mass basis of all the six Majorana neutrinos. To lower the mass scales of heavy neutrinos, one is motivated to invoke the inverse seesaw mechanism but has to pay the price for a <em>fine-tuned</em> cancellation between its two sets of new degrees of freedom, in which case the largeness of active flavor mixing is an <em>emergent</em> phenomenon as well. A comparison between the <em>approximate</em> seesaw relations in the flavor basis and those <em>exact</em> ones in the mass basis is also made.</div></div>","PeriodicalId":54712,"journal":{"name":"Nuclear Physics B","volume":"1013 ","pages":"Article 116853"},"PeriodicalIF":2.5000,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Nuclear Physics B","FirstCategoryId":"101","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0550321325000628","RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"PHYSICS, PARTICLES & FIELDS","Score":null,"Total":0}
引用次数: 0
Abstract
While the canonical seesaw mechanism provides a most natural qualitative interpretation of tiny masses for the three active neutrinos, it offers no explanation for their large flavor mixing effects. The latter can be regarded as an emergent consequence of this mechanism, in which case we are left with an intriguing cross seesaw framework in the mass basis of all the six Majorana neutrinos. To lower the mass scales of heavy neutrinos, one is motivated to invoke the inverse seesaw mechanism but has to pay the price for a fine-tuned cancellation between its two sets of new degrees of freedom, in which case the largeness of active flavor mixing is an emergent phenomenon as well. A comparison between the approximate seesaw relations in the flavor basis and those exact ones in the mass basis is also made.
期刊介绍:
Nuclear Physics B focuses on the domain of high energy physics, quantum field theory, statistical systems, and mathematical physics, and includes four main sections: high energy physics - phenomenology, high energy physics - theory, high energy physics - experiment, and quantum field theory, statistical systems, and mathematical physics. The emphasis is on original research papers (Frontiers Articles or Full Length Articles), but Review Articles are also welcome.