提升半轻子重子衰变中的有效场论简并性
Lifting Effective-Field-Theory Degeneracies in Semileptonic Heavy-Baryon Decays
AI总结：
利用格点QCD螺旋度形状因子分析Λ_b→Λ_cτν̄_τ等重子衰变，发现τ极化是区分当前R(D)和R(D^*)测量中未解决的有效场论简并性的关键，标量型新物理会产生大的极化偏移和低q^2谱形变。
摘要：
半轻子重子衰变为探测b→c τν̄_τ过程中可能的轻子味普适性破坏的螺旋度结构提供了灵敏探针。我们利用具有完全协方差传播的格点QCD螺旋度形状因子，对Λ_b→Λ_cτν̄_τ及相关重子模式进行了有效场论分析。将介子兼容的EFT解传播到重子观测量空间(R_{Λ_c}, P_τ, A_{\rm FB})中，我们表明τ极化是提升当前R(D)和R(D^*)测量中仍未解决的有效场论简并性的主要灵敏度来源。类矢量和类张量解仍聚集在标准模型预言附近，而包含标量的方向则产生大的极化位移和特征性的低q^2归一化微分谱形变。协方差感知分析表明，重子极化和微分观测量为半轻子新物理的洛伦兹结构提供了互补且独立的信息。P_τ(Λ_b→Λ_cτν̄_τ)和低q^2谱是未来在LHCb及未来味设施上检验半轻子τ味反常的特别有力的探针。
英文摘要：
Semileptonic heavy-baryon decays provide a sensitive probe of the helicity structure underlying possible lepton-flavor universality violation in $b\to c\,τ\barν_τ$ transitions. We perform an effective-field-theory analysis of $Λ_b\toΛ_cτ\barν_τ$ and related baryonic modes using lattice-QCD helicity form factors with full covariance propagation. Propagating meson-compatible EFT solutions into the baryonic observable space$(R_{Λ_c},\,P_τ,\,A_{\rm FB})$, we show that tau polarization provides the leading source of sensitivity for lifting EFT degeneracies that remain unresolved in current measurements of $R(D)$ and $R(D^\ast)$. Vector-like and tensor-like solutions remain clustered near theStandard-Model prediction, whereas scalar-containing directions produce large polarization displacements and characteristic low-$q^2$ deformations of the normalized differential spectrum. A covariance-aware analysis demonstrates that baryonic polarization and differential observables provide complementary and independent information on the Lorentz structure of semileptonic new physics. $P_τ(Λ_b\toΛ_cτ\barν_τ)$ and the low-$q^2$ spectrum as particularly powerful probes for future tests of semitauonic flavor anomalies at LHCb and future flavor facilities.
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