Chang Spencer, Fox Patrick J, Weiner Neal
Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, New York 10003, USA.
Phys Rev Lett. 2007 Mar 16;98(11):111802. doi: 10.1103/PhysRevLett.98.111802.
The presence of a new singlet scalar particle a can open up new decay channels for the Higgs boson, through cascades of the form h --> 2a --> X, possibly making discovery through standard model channels impossible. If a is CP odd, its decays are particularly sensitive to new physics. Quantum effects from heavy fields can naturally make h --> 4 g the dominant decay which is difficult to observe at hadron colliders, and is allowed by CERN LEP for m(h) > 82 GeV. However, there are usually associated decays, either h --> 2g2gamma or h --> 4gamma, which are more promising. The decay h-->4gamma is a clean channel that can discover both a and h. At the CERN LHC with 300 fb(-1) of luminosity, a branching ratio of order 10(-4) is sufficient for discovery for a large range of Higgs boson masses. With total luminosity of approximately 8 fb(-1), discovery at the Fermilab Tevatron requires more than 5 x 10(-3) in branching ratio.
新的单态标量粒子a的存在可以为希格斯玻色子开辟新的衰变通道，通过h→2a→X这样的级联衰变，这可能会使通过标准模型通道进行发现变得不可能。如果a是CP奇的，其衰变对新物理特别敏感。重场的量子效应自然会使h→4g成为主导衰变，这在强子对撞机上很难观测到，并且欧洲核子研究中心的大型正负电子对撞机（LEP）在m(h)>82 GeV时允许这种衰变。然而，通常存在相关联的衰变，要么是h→2g2γ，要么是h→4γ，这些衰变更有希望。h→4γ衰变是一个干净的通道，可以同时发现a和h。在欧洲核子研究中心的大型强子对撞机（LHC）上，当光度为300 fb⁻¹时，对于大范围的希格斯玻色子质量，10⁻⁴量级的分支比就足以实现发现。在费米实验室的万亿电子伏特加速器（Tevatron）上，当总光度约为8 fb⁻¹时，发现需要分支比超过5×10⁻³。
