[Paper Review] 750 GeV diphoton resonance at the ILC

H. Fujii, Junping Tian+1 more|arXiv (Cornell University)|Jul 14, 2016

Particle physics theoretical and experimental studies3 citations

TL;DR

This paper investigates the direct production of a hypothetical 750 GeV diphoton resonance (X) via $e^+e^- \to X\gamma$ and $e^+e^- \to XZ$ processes at the International Linear Collider (ILC). Using analytic amplitudes and full detector simulations, it demonstrates that the ILC can measure absolute cross-sections via recoil techniques and discover invisible and $b\bar{b}$ decay modes with high significance if branching ratios are sufficiently large.

ABSTRACT

In this paper we study the direct production of the diphoton resonance $X$ which has been suggested by 2015 data at the LHC, in $e^+e^- o X\gamma/XZ$ processes at the ILC. We derive an analytic expression for the scattering amplitudes of these processes, and present a comprehensive analysis for determining the properties of $X$ at the ILC. A realistic simulation study for $e^+e^- o X\gamma$ is performed based on the full detector simulation to demonstrate the capabilities of the ILC experiment. Complementary to the searches at the LHC, prospects of the measurement of the absolute values of production cross-section are obtained for the ILC using recoil technique without assuming decay modes of $X$. In addition, we have studied the searches for $X o m{invisible}$ and $X o b\bar{b}$ modes, which are challenging at the LHC, and found that these decay modes can be discovered with high significance if their branching ratios are large enough.

Motivation & Objective

• To explore the direct production of a 750 GeV diphoton resonance (X) at the ILC through $e^+e^- \to X\gamma$ and $e^+e^- \to XZ$ processes.
• To determine the properties of X using analytic scattering amplitudes and full detector simulations.
• To measure absolute production cross-sections of X without assuming its decay modes, using the recoil technique.
• To investigate the discovery potential of elusive decay modes such as $X \to \text{invisible}$ and $X \to b\bar{b}$, which are challenging at the LHC.

Proposed method

• Derives analytic expressions for the scattering amplitudes of $e^+e^- \to X\gamma$ and $e^+e^- \to XZ$ processes to model resonance production.
• Performs a realistic simulation of $e^+e^- \to X\gamma$ using full detector simulation to assess ILC's sensitivity and reconstruction capabilities.
• Applies the recoil technique to measure the absolute cross-section of X production without prior knowledge of its decay modes.
• Analyzes the discovery potential for $X \to \text{invisible}$ and $X \to b\bar{b}$ decays by evaluating signal significance in the ILC environment.

Experimental results

Research questions

• RQ1 Can the ILC directly probe the 750 GeV diphoton resonance via $e^+e^- \to X\gamma$ and $e^+e^- \to XZ$ processes with high precision?
• RQ2 To what extent can the ILC measure the absolute production cross-section of X without assuming its decay modes?
• RQ3 Can the ILC discover $X \to \text{invisible}$ and $X \to b\bar{b}$ decay modes with high significance if their branching ratios are large?
• RQ4 How do the ILC's capabilities complement those of the LHC in probing the properties of the 750 GeV resonance?

Key findings

• The ILC can measure the absolute production cross-section of the 750 GeV diphoton resonance using the recoil technique without assuming its decay modes.
• The full detector simulation confirms the ILC's capability to reconstruct the $X\gamma$ final state with high efficiency and resolution.
• The $X \to \text{invisible}$ decay mode can be discovered with high significance if its branching ratio is large enough, due to missing energy signatures.
• The $X \to b\bar{b}$ decay mode is also discoverable with high significance at the ILC, offering a complementary channel to LHC searches.
• The ILC provides a clean environment for precision measurements, enabling complementary constraints to LHC results on the resonance's properties.