[Paper Review] SUSY effects in Higgs productions at high energy $e^+e^-$ colliders

Junjie Cao, Chengcheng Han+4 more|arXiv (Cornell University)|Oct 4, 2014

Particle physics theoretical and experimental studies34 references4 citations

TL;DR

This paper investigates supersymmetry (SUSY) effects in Higgs boson production at high-energy $e^+e^-$ and photon colliders, focusing on $e^+e^- \to Zh$, $\gamma\gamma \to h \to b\bar{b}$, and exotic Higgs processes $e^+e^- \to Zh_1$ and $e^+e^- \to A_1h$ in the NMSSM. It finds that SUSY corrections to $e^+e^- \to Zh$ reach a few percent, $\gamma\gamma \to h$ cross sections can be enhanced by 20%, and $Zh_1$ production reaches 60 fb at 250 GeV, offering a probe for non-minimal SUSY models.

ABSTRACT

Considering the constraints from collider experiments and dark matter detections, we investigate the SUSY effects in the Higgs productions $e^+e^- o Zh$ at an $e^+e^-$ collider with a center-of-mass energy above 240 GeV and $γγ o h o b\bar{b}$ at a photon collider with a center-of-mass energy above 125 GeV. In the parameter space allowed by current experiments, we find that the SUSY corrections to $e^+e^- o Zh$ can reach a few percent and the production rate of $γγ o h o b\bar{b}$ can be enhanced by a factor of 1.2 over the SM prediction. We also calculate the exotic Higgs productions $e^+e^- o Zh_1$ and $e^+e^- ightarrow A_1h$ in the next-to-minimal supersymmetric model (NMSSM) ($h$ is the SM-like Higgs, $h_1$ and $A_1$ are respectively the CP-even and CP-odd singlet-dominant Higgs bosons which can be much lighter than $h$). We find that at a 250 GeV $e^+e^-$ collider the production rates of $e^+e^- ightarrow Zh_1$ and $e^+e^- o A_1h$ can reach 60 fb and 0.1 fb, respectively.

Motivation & Objective

• To assess the impact of supersymmetry (SUSY) on Higgs production processes at high-energy $e^+e^-$ and photon colliders, considering current experimental constraints.
• To investigate whether indirect SUSY signals can be detected via precision measurements of Higgs couplings and exotic Higgs production in the NMSSM.
• To evaluate the sensitivity of future $e^+e^-$ colliders (e.g., CEPC, ILC, TLEP) to non-minimal SUSY through rare Higgs channels.
• To quantify the size of SUSY corrections in $e^+e^- \to Zh$ and $\gamma\gamma \to h \to b\bar{b}$, accounting for LHC Higgs data and dark matter detection limits.

Proposed method

• A global parameter scan is performed in the pMSSM and CMSSM frameworks, incorporating constraints from LHC Higgs data, dark matter relic density, and direct SUSY searches.
• One-loop electroweak and SUSY corrections are calculated for $e^+e^- \to Zh$ using effective field theory and full one-loop diagrams.
• The $\gamma\gamma \to h \to b\bar{b}$ process is evaluated with loop contributions from charged SUSY particles, including charginos and charged Higgses.
• Exotic Higgs production channels $e^+e^- \to Zh_1$ and $e^+e^- \to A_1h$ are studied in the NMSSM, where $h_1$ and $A_1$ are singlet-dominant Higgs bosons lighter than the SM-like Higgs.
• Cross sections are computed at $\sqrt{s} = 250$ GeV for $e^+e^-$ and above 125 GeV for $\gamma\gamma$ collisions, with kinematic and coupling constraints applied.
• The analysis includes the $hZZ$ coupling deviation from the SM as a key control parameter, especially for $Zh_1$ production.

Experimental results

Research questions

• RQ1 Can SUSY effects in $e^+e^- \to Zh$ production be detected at the percent level at a 250 GeV $e^+e^-$ collider, given current LHC and dark matter constraints?
• RQ2 To what extent can the $\gamma\gamma \to h \to b\bar{b}$ cross section be enhanced by SUSY loop contributions in a photon collider?
• RQ3 What are the production rates for exotic Higgs states $Zh_1$ and $A_1h$ in the NMSSM at a 250 GeV $e^+e^-$ collider?
• RQ4 How sensitive are the $Zh_1$ and $A_1h$ production cross sections to the $hZZ$ coupling deviation from the SM value?
• RQ5 Can the $e^+e^- \to Zh_1$ and $e^+e^- \to A_1h$ channels serve as viable probes for non-minimal SUSY models like the NMSSM?

Key findings

• SUSY corrections to $e^+e^- \to Zh$ reach up to a few percent in the parameter space allowed by current LHC and dark matter constraints.
• The $\gamma\gamma \to h \to b\bar{b}$ cross section can be enhanced by a factor of 1.2 over the SM prediction due to SUSY loop contributions, particularly from charged Higgs and charginos.
• At $\sqrt{s} = 250$ GeV, the $e^+e^- \to Zh_1$ production rate reaches up to 60 fb in the NMSSM, with the cross section increasing with $h_1$ mass due to enhanced $h_1ZZ$ coupling from mixing.
• The $e^+e^- \to A_1h$ production rate reaches a maximum of 0.1 fb, which is significantly smaller than $Zh_1$, due to weaker $ZA_1h$ coupling and kinematic suppression at low $A_1$ masses.
• The $Zh_1$ cross section is highly sensitive to deviations of the $hZZ$ coupling from the SM value, dropping sharply when the coupling approaches the SM value.
• The $A_1h$ channel remains detectable even when $hZZ$ coupling is SM-like, with a cross section of up to 0.1 fb, indicating robustness to $hZZ$ coupling variations.