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arXiv · 1908.04048

F2F, a model-independent method to determine the mass and width of a particle in the presence of interference

Li-Gang Xia
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Abstract

It is generally believed that any particle to be discovered will have a TeV-order mass. Given its great mass, it must have a large decay width. Therefore, the interference effect will be very common if they and the Standard-Model (SM) particles contribute to the same final state.However, the interference effect could make a new particle show up not like a resonance, and it is difficult to search and measure its properties. In this work, a model-independent method, F2F (Fit To Fourier coefficients), is proposed to search for an unknown resonance and to determine its mass ($M$) and width ($\Gamma$) in the presence of interference. Basically we express the sum of reosnant signal and the interference as a cosine Fourier series and relate the Fourier coefficients with the mass and width. The relation is based on the general propagator form, $1/(x^2-M^2+iM\Gamma)$. Thus it does not need any signal model. Toy experiments show that the obtained mass and width agree well with the inputs with a similar precision as using an explicit signal model. We also show that we can apply this method to measure the Stardard-Model Higgs width and to make statistic interpretation in searching for new resonance allowing for interference.

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Li-Gang Xia. 2019-08-12. F2F, a model-independent method to determine the mass and width of a particle in the presence of interference. https://arxiv.org/abs/1908.04048

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