Confronting dark matter with the diphoton excess from a parent resonance decay

Confronting a New Three-loop Seesaw Model with the 750 GeV Diphoton Excess

We propose a new type of radiative neutrino model with a local hidden $U(1)$ symmetry, in which neutrino masses are induced at the three loop level, and discuss the muon anomalous magnetic moment, and dark matter candidates therein. By allowing the hypercharges larger than 3/2 for new fields that contribute to the neutrino masses and making them decay into the standard model fields appropriately, we introduce a lot of new particles with multiple electrical charges in a natural manner. As a by-product, we can accommodate the 750 GeV diphoton excess depending on the hypercharge quantum numbers o…

Symmetries and composite dynamics for the 750 GeV diphoton excess

The ATLAS and CMS experiments at LHC observe small excesses of diphoton events with invariant mass around 750 GeV. Here we study the possibility of nearly parity degenerate and vector-scalar degenerate spectra as well as composite dynamics in 2 scenarios for explaining the excess: Production of a pseudo-scalar via gluon or photon fusion or via decay of a parent particle together with soft additional final states. We discuss possible underlying realizations of the scenarios motivated by dynamical models of electroweak symmetry breaking (without new coloured states) and fermion masses.

Confronting minimal freeze-in models with the LHC

We present a class of dark matter models, in which the dark matter particle is a feebly interacting massive particle (FIMP) produced via the decay of an electrically charged and/or colored parent particle. Given the feeble interaction, dark matter is produced via the freeze-in mechanism and the parent particle is long-lived. The latter leads to interesting collider signatures. We study current LHC constrains on our models arising from searches for heavy charged particles, disappearing tracks, displaced leptons and displaced vertices. We demonstrate not only that collider searches can be a powe…

Characterising the 750 GeV diphoton excess

We study kinematic distributions that may help characterise the recently observed excess in diphoton events at 750 GeV at the LHC Run 2. Several scenarios are considered, including spin-0 and spin-2 750 GeV resonances that decay directly into photon pairs as well as heavier parent resonances that undergo three-body or cascade decays. We find that combinations of the distributions of the diphoton system and the leading photon can distinguish the topology and mass spectra of the different scenarios, while patterns of QCD radiation can help differentiate the production mechanisms. Moreover, missi…

对抗再加热期间暗物质冻结注入与暴胀约束的研究

Confronting Dark Matter Freeze-In during Reheating with Constraints from Inflation

本研究探讨非瞬时再加热对暗物质冻结注入产生的影响，发现其依赖于暴胀模型，并利用CMB约束推导母粒子衰变长度下限，与LLP搜索比较，强调暴胀动力学对解释对撞机信号的重要性。

LEP上臭名昭著的95 GeV $\rm b \bar b$ 超出：两个b还是不是两个b？

The infamous 95 GeV $\rm b \bar b$ excess at LEP: Two b or not two b?

针对有说法称LEP的bb质量超出可佐证LHC 95 GeV双光子超出是新标量粒子的观点，研究者核查LEP公开记录后发现，LEP数据强烈不支持95-100 GeV范围内存在新物理。