Searching for New Physics with b→sτ^{+}τ^{-} Processes

Area of Science:

• High Energy Physics
• Particle Physics
• Beyond Standard Model Physics

Background:

• Intriguing hints for lepton flavor universality (LFU) violation have emerged in semileptonic B decays, specifically in charged-current (b→cℓ⁻ν̄ℓ) and neutral-current (b→sℓ⁺ℓ⁻) transitions.
• Deviations observed in R<0xE1><0xB5><0x83> and R<0xE1><0xB5><0x83>* suggest new physics impacting tau leptons, while LHCb data indicates deviations in b→sμ⁺μ⁻ processes, pointing towards new physics affecting muons.

Purpose of the Study:

• To predict the branching ratios of B→Kτ⁺τ⁻, B→K*τ⁺τ⁻, and Bs→ϕτ⁺τ⁻ decays.
• To investigate the potential for large LFU-violating effects in b→sτ⁺τ⁻ transitions, considering new physics (NP) explanations for observed anomalies.
• To assess the observability of these predicted enhancements at current and future experiments like LHCb and Belle II.

Main Methods:

• Calculation of branching ratios for B→Kτ⁺τ⁻, B→K*τ⁺τ⁻, and Bs→ϕτ⁺τ⁻ decays.
• Inclusion of NP effects through modifications in Wilson coefficients C<0xE2><0x82><0x99>(ττ) and C<0xE2><0x82><0x8A>(ττ).
• Assumption of a common NP explanation for anomalies in R<0xE1><0xB5><0x83>, R<0xE1><0xB5><0x83>(*), and R<0xE1><0xB5><0x8B> to explore LFU violation.

Main Results:

• A significant enhancement of b→sτ⁺τ⁻ processes by approximately three orders of magnitude compared to the Standard Model (SM) predictions is found.
• Under general assumptions for NP, the predicted branching ratios for B→Kτ⁺τ⁻, B→K*τ⁺τ⁻, and Bs→ϕτ⁺τ⁻ are within the observable range of LHCb and Belle II.
• The results suggest that LFU-violating effects in these decays could be substantial.

Conclusions:

• The study provides strong theoretical motivation for searching for new physics in b→sτ⁺τ⁻ decays.
• Experimental verification of the predicted enhancements would provide compelling evidence for physics beyond the Standard Model.
• Future measurements at LHCb and Belle II are crucial for probing these predicted phenomena and potentially discovering new sources of lepton flavor universality violation.