Non-compact nonlinear sigma models

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• 作者：Claudia de Rham ; ^{claudia.deRham@case.edu" class="auth_mail" title="E-mail the corresponding author} ; Andrew J. Tolley ; ^{Andrew.J.Tolley@case.edu" class="auth_mail" title="E-mail the corresponding author} ; Shuang-Yong Zhou ; ^{Shuangyong.Zhou@case.edu" class="auth_mail" title="E-mail the corresponding author}
• 刊名：Physics Letters B
• 出版年：2016
• 出版时间：10 September 2016
• 年：2016
• 卷：760
• 期：Complete
• 页码：579-583
• 全文大小：262 K

文摘

The target space of a nonlinear sigma model is usually required to be positive definite to avoid ghosts. We introduce a unique class of nonlinear sigma models where the target space metric has a Lorentzian signature, thus the associated group being non-compact. We show that the would-be ghost associated with the negative direction is fully projected out by 2 second-class constraints, and there exist stable solutions in this class of models. This result also has important implications for Lorentz–invariant massive gravity: There exist stable nontrivial vacua in massive gravity that are free from any linear vDVZ-discontinuity and a Λ₂${\mathrm{\Lambda }}_2$ decoupling limit can be defined on these vacua.