微中子蹺蹺板模型內之輕、重微中子的大程度混合對於希格斯玻色子衰變的影響

在多於一個微中子世代的蹺蹺板模型內，如果重微中子( N )的質量在100 GeV 左右，輕微中子(ν)和重微中子可以有相當大程度的混合。我們更進一步的探究了這種大程度混合的可能，同時考慮了目前實驗數據的限制，在此論文裡我們研究了I型和III型蹺蹺板模型內這種輕、重微中子大程度混合的情況對於希格斯玻色子(h)衰變的影響。在I型蹺蹺板模型內，我們發現希格斯玻色子可以衰變成一對輕、重微中子(h → ν N )，對於質量相對輕的希格斯玻色子而言，這個新的衰變模式與標準模型的貢獻相比有機會增加高達近30％的希格斯玻色子總衰變寬度，這會大大影響在大強子對撞機(LHC)裡尋找希格斯玻色子的工作。重微中子隨後迅速衰變為三個輕的費米子，使得整個 h → ν N 衰變模式可以有效地被看成是一個希格斯玻色子的四體衰變模式。我們進一步的發現，對於存在輕、重微中子大程度混合的情況，這個新的希格斯玻色子四體衰變模式之衰變率可以數倍的大於標準模型裡相應的希格斯玻色子四體衰變模式之衰變率。因此，這個新的希格斯玻色子四體衰變模式在實驗上可以提供一個潛在的重要窗口以揭示潛藏的微中子蹺蹺板機制。然而，在III型蹺蹺板模型內，因為實驗數據給了輕、重微中子的混合矩陣元較強的限制，同時因為實驗數據加諸較高的質量下限於重微中子的質量上，這些因素使得大程度輕、重微中子混合的存在只會微小程度(大約5%)的修改希格斯玻色子的總衰變寬度，遠小於I型蹺蹺板模型裡的情況。因此，比起I型蹺蹺板模型，在III型蹺蹺板模型內之希格斯玻色子衰變為四個輕的費米子的模式較無法提供人們資訊以探究潛藏的微中子蹺蹺板機制。

關鍵字

超越標準模型；希格斯玻色子；微中子質量；蹺蹺板機制；重微中子；大強子對撞機； TeV尺度的物理

並列摘要

In seesaw models with more than one generation of light and heavy neutrinos, ν and N, respectively, it is possible to have sizable mixing between them for heavy neutrino masses of order 100 GeV or less. We explore this possibility further, taking into account current experimental constraints, and study its effect on Higgs boson decays in the contexts of seesaw models of types I and III. We find that in the type-I case the Higgs decay into a pair of light and heavy neutrinos, h → νN, could increase the total Higgs width in the standard model by up to almost 30% for a relatively light Higgs boson, which would significantly affect Higgs searches at the LHC. The subsequent prompt decay of N into three light fermions makes this Higgs decay effectively a four body decay. We further find that, in the presence of the large light-heavy mixing, these four body Higgs decays can have rates a few times larger than their standard model counterparts and therefore could provide a potentially important window to reveal the underlying seesaw mechanism. However, in type-III seesaw model, due to the stronger experimental constraints on the elements of the mixing matrix U_{νN} and also to the lower limit on the heavy lepton masses, the large light-heavy mixing gives rise to modifications of the SM Higgs total width that are modest, roughly only 5%, much smaller than those in the type-I case. As a consequence, the Higgs decays into four light fermions in this case would be less sensitive for probing the underlying seesaw mechanism than their type-I counterparts.

並列關鍵字

beyond the standard model ； Higgs boson ； neutrino mass ； seesaw mechanism ； heavy neutrino ； Large Hadron Collider ； TeV scale physics

參考文獻

[4] T. Han and B. Zhang, Phys. Rev. Lett. 97, 171804 (2006) [arXiv:hepph/0604064]; B. Bajc, M. Nemevsek, and G. Senjanovic, Phys. Rev. D 76, 055011 (2007) [arXiv:hep-ph/0703080]; W. Chao, Z.G. Si, Z.Z. Xing, and S. Zhou, Phys. Lett. B 666, 451 (2008) [arXiv:0804.1265 [hep-ph]]; P. Fileviez Perez, T. Han, G.Y. Huang, T. Li, and K.Wang, Phys. Rev. D 78, 015018 (2008) [arXiv:0805.3536 [hep-ph]]; F. del Aguila and J.A. Aguilar-Saavedra, Phys. Lett. B 672, 158 (2009) [arXiv:0809.2096 [hep-ph]]; Z.Z. Xing, Int. J. Mod. Phys. A 24, 3286 (2009) [arXiv:0901.0209 [hep-ph]]; A. Atre, T. Han, S. Pascoli, and B. Zhang, JHEP 0905, 030 (2009) [arXiv:0901.3589 [hep-ph]]; N. Haba, S. Matsumoto, and K. Yoshioka, Phys. Lett. B 677 (2009) 291 [arXiv:0901.4596 [hep-ph]]; A. Arhrib, B. Bajc, D. K. Ghosh, T. Han, G. Y. Huang, I. Pul-jak and G. Senjanovic, Phys. Rev. D 82, 053004 (2010) [arXiv:0904.2390 [hepph]].

[17] S. Weinberg, “The Quantum theory of fields. Vol. 1: Foundations,” Cambridge, UK: Univ. Pr. (1995) 609 p

[22] H. Georgi, Ann. Rev. Nucl. Part. Sci. 43, pg.209, 1993.

[34] K. Fujikawa, Phys. Rev. D 83, 105012 (2011)

[36] S. R. Coleman and E. J. Weinberg, Phys. Rev. D 7, 1888 (1973).

國際替代計量

微中子蹺蹺板模型內之輕、重微中子的大程度混合對於希格斯玻色子衰變的影響

全文下載

主題瀏覽