U-boson production in e+ e- annihilations, psi and Upsilon decays, and Light Dark Matter
U-boson production in e+ e- annihilations, psi and Upsilon decays, and Light Dark Matter
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DOI：
10.1103/physrevd.75.115017
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发表时间：
2007-02
影响因子：
5
通讯作者：
P. Fayet
中科院分区：
文献类型：
--
作者：
P. Fayet
我们回顾了一个新的轻规范玻色子是如何在标准模型的超对称扩展中出现的，它是如何在一个额外的单重态超场中出现的，以及它是如何表现得非常像一个轻伪标量，相应的对称性在比弱电更高的尺度上被破坏。这样一个新的规范玻色子U，很轻，耦合非常弱，允许轻暗物质粒子，它可能是来自银河系凸起的511keV线的原点。它能直接在e+e-湮灭中找到吗？不那么容易，由于对其耦合的各种限制，特别是轴向耦合，导致类似轴线的行为或额外的宇称破坏效应。寻找衰变Upsilon->+不可见U可用来严格限制其与电子的轴向耦合f_a=f_BA，使其小于约10^-6m_U(MeV)。原则上，与电子的矢量耦合可能更大。我们从g_u-2中发现，在合理的假设下，对于m_U伽马U，这种耦合最大可以达到~1.3×10~(-3)。尽管如此，U交换可以提供合适尺寸的LDM粒子的湮没截面，即使这可能要求亮暗物质具有相对较强的自相互作用。
We recall how a new light gauge boson emerged in Supersymmetric extensions of the Standard Model with an extra singlet superfield, and how it could behave very much as a light pseudoscalar, with the corresponding symmetry broken at a scale higher than electroweak. Such a new gauge boson U, light and very weakly coupled, allows for Light Dark Matter particles, which could be at the origin of the 511 keV line from the galactic bulge. Could it be found directly in e+e- annihilations ? Not so easily, due to various constraints on its couplings, especially axial ones, leading to an axionlike behavior or extra parity-violation effects. Searches for the decay Upsilon -> gamma + invisible U may be used to constrain severely its axial coupling to the electron, f_eA = f_bA, to be less than about 10^-6 m_U(MeV). The vector coupling to the electron may in principle be larger. We find from g_mu-2, under reasonable assumptions, that this coupling can be at most as large as ~ 1.3 10^-3, for m_U gamma U. Despite that, U exchanges can provide annihilation cross sections of LDM particles of the appropriate size, even if this may require that light dark matter be relatively strongly self-interacting.