论文标题
$ z_2 $对称性的两个希格斯双重模型上的域墙约束
Domain Wall Constraints on Two Higgs Doublet Models with $Z_2$ Symmetry
论文作者
论文摘要
具有自发损坏的$ Z_2 $对称性的两个Higgs Doublet模型（2HDM）预测Electroweak量表的域壁的生产。我们从当今的域壁不主导宇宙的要求中，对I型和II类型2HDM的模型参数产生了宇宙学约束。对于I型2HDM，我们将关键参数$ \tanβ> 10^5 $的下限推导，用于广泛的Higgs-Boson块$ \ SIM $ \ SIM $ 100 GEV或更大接近标准模型对齐限制。此外，我们对2HDM进行数值模拟，并具有近似$ Z_2 $对称性，但初始条件有偏见。在这两种情况下，我们都发现域墙网络不稳定，因此，在晚期无法生存。在这些模型中，域墙经历了对缩放率的指数抑制，这可以帮助改善精确离散对称性的严格约束。对于具有柔和破碎的$ Z_2 $对称性的2HDM，我们将这种指数抑制的大小与软性破坏性的双线性参数$ m_ {12} $联系起来，允许将限制放在订单$ $ $ $ eV的参数上，例如，可以避免域壁统治。 In particular, for Type-II 2HDMs, we obtain a corresponding lower limit on the CP-odd phase $θ$ generated by QCD instantons, $θ\ \stackrel{>}{{}_\sim}\ 10^{-11}/(\sinβ\cosβ)$, which is in some tension with the upper limit of $θ\ \ stackrel {<} {{} _ \ sim} \ 10^{ - 11} $ - $ 10^{ - 10} $，源自非零中子电动偶极力矩的非观察。对于$ Z_2 $ -SMMETRIC 2HDM具有偏见的初始条件，我们能够将指数抑制的大小与有偏见的参数$ \ VAREPSILON $相关联，以避免域壁的统治。
The Two Higgs Doublet Model (2HDM) with spontaneously broken $Z_2$ symmetry predicts a production of domain walls at the electroweak scale. We derive cosmological constraints on model parameters for both Type-I and Type-II 2HDMs from the requirement that domain walls do not dominate the Universe by the present day. For Type-I 2HDMs, we deduce the lower bound on the key parameter $\tanβ> 10^5$ for a wide range of Higgs-boson masses $\sim$ 100 GeV or greater close to the Standard Model alignment limit. In addition, we perform numerical simulations of the 2HDM with an approximate as well as an exact $Z_2$ symmetry but biased initial conditions. In both cases, we find that domain wall networks are unstable and, hence, do not survive at late times. The domain walls experience an exponential suppression of scaling in these models which can help ameliorate the stringent constraints found in the case of an exact discrete symmetry. For a 2HDM with softly-broken $Z_2$ symmetry, we relate the size of this exponential suppression to the soft-breaking bilinear parameter $m_{12}$ allowing limits to be placed on this parameter of order $μ$eV, such that domain wall domination can be avoided. In particular, for Type-II 2HDMs, we obtain a corresponding lower limit on the CP-odd phase $θ$ generated by QCD instantons, $θ\ \stackrel{>}{{}_\sim}\ 10^{-11}/(\sinβ\cosβ)$, which is in some tension with the upper limit of $θ\ \stackrel{<}{{}_\sim}\ 10^{-11}$--$10^{-10}$, as derived from the non-observation of a non-zero neutron electric dipole moment. For a $Z_2$-symmetric 2HDM with biased initial conditions, we are able to relate the size of the exponential suppression to a biasing parameter $\varepsilon$ so as to avoid domain wall domination.
