Field Theory Models without the Cosmological Constant Problem
Field Theory Models without the Cosmological Constant Problem
复制标题
没有宇宙常数问题的场论模型
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
A. Kaganovich
中科院分区：
文献类型：
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作者：
E. Guendelman;A. Kaganovich
我们在引力理论的背景下研究场论模型，其要求是作用中的积分度量不一定是 \sqrt{-g} ，而是通过附加自由度动态确定，例如四个标量场 \phi_{a} 。我们研究了理论一般结构的三种可能性： (A) 总作用的形式为 S=\int\Phi Ld^{4}x，其中测度 \Phi 是根据标量 \phi_{a} 构建的，使得 L\ 到 L+const 的变换不会影响运动方程。然后，由拉格朗日密度 L 的任意函数得到的测度场 (SGMF) \phi_{a} 的无限维平移群是作用的对称群。 (B) 总作用的形式为 S=S_{1}+S_{2}, S_{1}=\int\Phi L_{1}d^{4}x, S_{2}=\int\sqrt{-g}L_{2}d^{4}x，这是唯一与 (A) 不同且在 SGMF 下不变的模型（但现在 f_{a}= f_{a}(L_{1})）。类似地，现在只有 S_{1} 满足 L_{1}\ 到 L_{1}+const 的变换不会影响运动方程的要求。在情况(A)和情况(B)中都假设L、L_{1}、L_{2}不依赖于\phi_{a}。 (C) 该动作包含一个破坏 SGMF 对称性的项。结果表明，在情况 (A) 和 (B) 的一阶形式中，CCP 已得到解决：在没有微调的情况下，有效势在真真空状态 (TVS) 中消失。在情况 (C) 中，SGMF 对称性的破缺导致 TVS 的能量密度非零。
We study field theory models in the context of a gravitational theory based on the requirement that the measure of integration in the action is not necessarily \sqrt{-g} but it is determined dynamically through additional degrees of freedom, like four scalar fields \phi_{a}. We study three possibilities for the general structure of the theory: (A) The total action has the form S=\int\Phi Ld^{4}x where the measure \Phi is built from the scalars \phi_{a} in such a way that the transformation L\to L+const does not effect equations of motion. Then an infinite dimensional shifts group of the measure fields (SGMF) \phi_{a} by arbitrary functions of the Lagrangian density L is a symmetry group of the action. (B) The total action has the form S=S_{1}+S_{2}, S_{1}=\int\Phi L_{1}d^{4}x, S_{2}=\int\sqrt{-g}L_{2}d^{4}x which is the only model different from (A) and invariant under SGMF (but now with f_{a}= f_{a}(L_{1})). Similarly, now only S_{1} satisfies the requirement that the transformation L_{1}\to L_{1}+const does not effect equations of motion. Both in the case (A) and in the case (B) it is assumed that L, L_{1}, L_{2} do not depend on \phi_{a}. (C) The action includes a term which breaks the SGMF symmetry. It is shown that in the first order formalism in cases (A) and (B) the CCP is solved: the effective potential vanishes in a true vacuum state (TVS) without fine tuning. In the case (C), the breaking of the SGMF symmetry induces a nonzero energy density for the TVS.