Cosmological imprints of Dirac neutrinos in a keV-vacuum 2HDM  

作　　者：李少平 李新强 严鑫帅 杨亚东 Shao-Ping Li;Xin-Qiang Li;Xin-Shuai Yan;Ya-Dong Yang(Institute of Particle Physics and Key Laboratory of Quark and Lepton Physics(MOE),Central China Normal University,Wuhan 430079,China;Center for High Energy Physics,Peking University,Beijing 100871,China;Institute of Particle and Nuclear Physics,Henan Normal University,Xinxiang 453007,China)

机构地区：[1]Institute of Particle Physics and Key Laboratory of Quark and Lepton Physics(MOE),Central China Normal University,Wuhan 430079,China [2]Center for High Energy Physics,Peking University,Beijing 100871,China [3]Institute of Particle and Nuclear Physics,Henan Normal University,Xinxiang 453007,China

出　　处：《Chinese Physics C》2023年第4期110-121,共12页中国物理C（英文版）

基　　金：Supported by the National Natural Science Foundation of China(12135006,12075097,12047527,11775092);by the Fundamental Research Funds for the Central Universities(CCNU20TS007,CCNU19TD012,CCNU22LJ004)。

摘　　要：The Dirac neutrino masses could be simply generated by a neutrinophilic scalar doublet with a vacuum being dramatically different from the electroweak one.While the case with an eV-scale vacuum has been widely explored previously,we exploit in this work the desert where the scalar vacuum is of O(keV)scale.In this regime,there would be rare hope to probe the keV-vacuum neutrinophilic scalar model via the lepton-flavor-violating processes,which makes it distinguishable from the widely considered eV-scale vacuum.Although such a keV-vacuum scenario is inert in the low-energy flavor physics,we show that the baryogenesis realized via the lightest Dirac neutrino can be a natural candidate in explaining the baryon asymmetry of the Universe.Furthermore,the Dirac neutrinos with a keV-vacuum scalar can generate a shift of the effective neutrino number within the range 0.097≤ΔN_(eff)≤0.112,which can be probed by the future Simons Observatory experiments.In particular,the model with a minimal valueΔN_(eff)=0.097 can already be falsified by the future CMB Stage-Ⅳand Large Scale Structure surveys,providing consequently striking exploratory avenues in the cosmological regime for such a keV-vacuum scenario.

关 键 词：2HDM Dirac neutrinos LEPTOGENESIS effective neutrino number shift 

分 类 号：O572.321[理学—粒子物理与原子核物理]