河南省高校杰出科研人才創(chuàng)新 工程項目（haipurt）

1、Little Higgs,為了自然地得到一個較輕的Higgs粒子，人們早在二十世紀(jì)七十年代就提出了把Higgs粒子看作贗哥德斯通粒子，以保持它的小質(zhì)量，這就是小Higgs理論最初的思想(Georgi)八十年代Georgi和Kaplan以這個思想構(gòu)造了一個這樣的模型，但是從電弱標(biāo)度到該模型的截斷標(biāo)度仍然需要精細(xì)調(diào)節(jié)二十世紀(jì)初，受“Dimension（De)Construction”(Arkani-Hamed, Cohen, Geo

2、rgi) 的啟發(fā)，人們引進(jìn)了協(xié)同對稱破缺機(jī)制，將Higgs粒子構(gòu)造成贗哥德斯通粒子的小黑格斯模型成功建立起來(Arkani-Hamed,Cohen,Georgi,Katz,Nelson),Thanks 王磊,Higgs boson is a pseudo Nambu-Goldstone boson of an approximate global symmetry,At least two sets of intera

3、ctions are needed to break this global symmetry -- collective symmetry breaking,No one-loop quadratic divergence of Higgs mass,Motivation:,N. Arkani-Hamed, A. G. Cohen, A.E. Nelson, hep-ph/0105239,What is little Higg

4、s ？,,根據(jù)哥德斯通定理:,,比如,14 Goldstone boson fields,Collective Symmetry Breaking,,,,此時Higgs粒子變成贗哥德斯通粒子，在單圈獲得了質(zhì)量：,但這是單圈二次發(fā)散的質(zhì)量。所以我們必須做的更多才行啊,,,,,具有二次發(fā)散貢獻(xiàn)的Higgs質(zhì)量在兩圈出現(xiàn),,協(xié)同對稱破缺,Collective Symmetry Breaking,,,In the following we ta

5、ke littlest Higgs model to show how the quadratic divergences can be avoided at one loop level,Littlest Higgs Model,14 Goldstones,,,,,Gauge bosons: cause no quadratic divergence at 1-loop,Each of these two t

6、erms (like in SM) will cause quadratic divergence,M. Perelstein，hep-ph/0512128,But collective symmetry breaking forbid their existence,because each of them only contains one kind of interactions,,g1, g2 分別是兩個SU(2)的耦合,g’1

7、, g’2 分別是兩個U(1)的耦合,Each term contains two kinds of interactions (enough to break global symmetry to give Higgs mass),,Quadratic divergences from two diagrams cancel,Equivalently, in mass eigenstates ：,Top quark Yukawa

8、 interaction:,,,(i, j, k=1, 2, 3，x, y =4, 5),Top quark對Higgs質(zhì)量單圈二次發(fā)散的抵消,這三個圖對Higgs質(zhì)量的貢獻(xiàn)分別為,,所以，Higgs質(zhì)量單圈二次發(fā)散貢獻(xiàn)抵消,,,Han, Wang, Yang, Zhu, PRD87, 055004(2013),Wang, Yang, PRD84, 075024(2011),Phenomenology of little Higgs

9、,(1) The diphoton signal is suppressed,Wang, Yang, Zhu, PRD88, 075018 (2013),Signal of T-odd particles generally contains,(2) T-odd particles in LHT,The T-odd gauge bosons:,The T-odd fermions:,,, similar to SUSY,,Dark m

10、atter,Production processes at LHC,The decay modes have,LHC has reported constraints on,,Belyaev, Chen, Tobe, Yuan, PRD74, 115020 (2006),(3) Dark matter in LHT,Wu, Yang, Zhang, JHEP1612, 152 (2016),(4) Top-partners in LHT