对DESI动力学暗能量信号的序列有效再分析
A Sequentially-Valid Reanalysis of DESI's Dynamical Dark Energy Signal
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中文总结 AI 辅助
该研究用e过程再分析DESI BAO数据，发现其动力学暗能量信号脆弱且依赖特定设定，未提供可靠证据，建议未来巡天数据报告e过程值。
中文摘要 AI 辅助
DESI等巡天项目分阶段发布数据，每次发布都会引发对暗能量是否与宇宙学常数（ΛCDM）一致的新评估。标准的基于Wilks的σ值被解读为仅进行一次检验的结果，但在DR1、DR2、DR3及后续版本中重新审视同一问题会增加出现明显显著波动的概率。我们采用e过程（一种基于似然比的证据度量，在对累积数据重复检验时仍保持有效性）对DESI的重子声学振荡（BAO）动力学暗能量证据进行再分析：该方法能控制跨数据发布持续检验时的错误探测概率，无需引入试验因子惩罚。将其应用于DESI DR1→DR2的BAO序列时，结果高度依赖于检验设计用来探测的ΛCDM偏离类型：对于与DR2偏好方向一致的预先指定替代模型，运行证据达到M_DR2=33.97，超过了示例5%阈值20；证据几乎完全集中在LRG2红移 bin中，移除该 bin后运行e值降至M=0.49，略微倾向ΛCDM；当允许七个 bin中任意一个产生超额时，信号未通过视场外校正；其他与物理无关的替代模型也无法拒绝ΛCDM，而受物理驱动的 thawing-quintessence 替代模型比任何无关选择的拒绝力度更强。证据集中于LRG2这一特定情况，难以与平滑演化的状态方程相协调，因此数据指向的是脆弱的、单 bin的、依赖于具体设定的信号，而非动力学暗能量的可靠证据。我们建议未来DESI、Euclid、Roman和LSST的数据发布，在报告传统σ显著性的同时，一并报告随时有效的e过程值及其检验设定。
英文摘要
Surveys such as DESI release data in stages, and each release invites a fresh assessment of whether dark energy is consistent with a cosmological constant. Standard Wilks-based $σ$ values are interpreted as if the test were performed only once, yet revisiting the same question at DR1, DR2, DR3, and beyond inflates the chance of an apparently significant fluctuation. We reanalyse the DESI BAO evidence for dynamical dark energy using an e-process, a likelihood-ratio-based measure of evidence that remains valid under repeated looks at accumulating data: it controls the false-detection probability under continued testing across releases with no trials-factor penalty. Applied to the DESI DR1$\to$DR2 BAO sequence, the result depends strongly on which departures from $Λ$CDM the test is designed to detect. For a pre-specified alternative aligned with the DR2-preferred direction, the running evidence reaches $M_{DR2} = 33.97$, crossing an illustrative 5% threshold of 20. The evidence is concentrated almost entirely in the LRG2 redshift bin, and removing that bin reduces the running e-value to $M = 0.49$, mildly favouring $Λ$CDM. When allowing any of the seven bins to have produced the excess, the signal does not survive a look-elsewhere correction. Other physically agnostic alternatives also fail to reject $Λ$CDM, while a physically motivated thawing-quintessence alternative rejects more strongly than any agnostic choice. The concentration of evidence in LRG2 specifically is difficult to reconcile with a smoothly evolving equation of state. The data therefore points to a fragile, single-bin, specification-dependent signal rather than robust evidence for dynamical dark energy. We recommend that future DESI, Euclid, Roman, and LSST data releases report an anytime-valid e-process value with its test specification stated alongside conventional $σ$ significances.
