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[2026-09-08] · src BESIII Collaboration; Nature (2026-09-02), doi:10.1038/s41586-026-10818-8
CKM unitarity - the requirement that |V_ud|2 + |V_us|2 + |V_ub|2 = 1 - is one of the Standard Model's cleanest falsifiable predictions, and current kaon- and tau-based determinations of |V_us| sit in mild but persistent tension with it, a puzzle known as the Cabibbo angle anomaly. Hyperon semileptonic decays offer an independent handle on the same matrix element, but every prior measurement lacked enough kinematic information to isolate the individual form factors, leaving the channel effectively unusable for a precision extraction. BESIII gets around this by using the polarization and quantum entanglement of Lambda-Lambdabar pairs produced at the J/psi resonance: from 10.087 billion J/psi events they isolate 1854 +/- 49 double-tagged Lambda -> p e- nu-bar-e decays, and the correlations between the two hyperons' spins supply the missing kinematic constraints, yielding the first measured weak-electricity coupling and absolute branching fraction for this decay alongside the axial-vector and weak-magnetism couplings. Combined with lattice QCD input, the result is |V_us|_LQCD = 0.2339 +/- 0.0041 - consistent with CKM unitarity at the 1.4 sigma level, but about two standard deviations above the older Cabibbo-era kaon-based value, so it does not resolve the anomaly either way.
This does not settle the Cabibbo angle anomaly - the hyperon number lands roughly halfway between "unitarity is fine" and "kaons were right," which is its own kind of unhelpful - but it opens a genuinely independent channel for testing CKM unitarity, one that entanglement, not brute statistics, is what unlocked: BESIII gets Fermilab-comparable precision from a dataset about twenty times smaller because measuring one hyperon's decay now reveals information about its entangled partner that a lone measurement never could. That is the more durable result. Whatever the anomaly turns out to be - new physics or an underestimated systematic in one of the existing methods - a second independent extraction technique, applicable wherever entangled baryon pairs are produced, is now available to adjudicate it rather than everyone re-measuring the same kaons more precisely.
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[2026-09-08] · src twelve-keys/src/exercises/dorian/exercise.py
Piano gets today's block alone: it carries the longest gap of the three, and alto went yesterday, so the two chops-dependent instruments don't land back to back either way. It's modes & scales family's second lap, and rather than repeat lap one's altered scale — a dominant-tension sound built to resolve into a target chord — today moves to the opposite kind of scale: dorian, a plain diatonic minor mode with no altered tones, sitting over one static m7 chord with nowhere it needs to go. Key is B♭ minor, a fourth away from the one minor key this rotation has already used and, at five flats, one that does not read easily.
5 minutes: play the B♭ dorian scale (B♭ C D♭ E♭ F G A♭ B♭) one octave, hands separately, very slowly — then play B♭ natural minor (aeolian) immediately after, same tempo, same octave. The only difference is the 6th degree, G natural against G♭. Go back and forth between the two three times, listening for exactly where that one note changes the scale's color, before touching the two-octave exercise, which assumes the ear already has it.
The full two-octave exercise as written, both hands together, ascending and descending, quarter = 76, three times through without stopping. Success criterion: three consecutive clean passes with the natural 6th (G) landing squarely in time rather than rushed past or leaned on, and both hands arriving at the top and bottom of the octave jump together each time — the written fingering shifts hand position exactly at that jump, which is where ensembles most often come apart.
Over a slow, static B♭m7 left-hand vamp (root and fifth, one bar each, looping), improvise an 8-bar right-hand phrase using only B♭ dorian tones — no chord changes to lean on, so the phrase has to come from shaping motion and space rather than from resolving anything. This is the exact setting "So What" and "Impressions" use the scale for: a phrase that goes somewhere without the harmony pulling it there.
Stop after the three clean technical passes, or sooner if the hands start landing the octave jump out of sync — that's the vamp's demand quietly degrading into two separate scales played near each other rather than one scale played by two hands, and more reps at that point just rehearse the mismatch.
[2026-09-08] · src —
hearMiles Davis — So What (Kind of Blue) · Tidal · Spotify
The tune the exercise itself names as dorian's home turf: sixteen bars of D dorian answered by eight of E♭ dorian and back, with Bill Evans and the rhythm section never once implying a chord change under the melody. Listen to how Davis and Coltrane's solos build whole phrases with nothing to resolve into — the same demand today's musical target is asking of an 8-bar improvisation over one static chord.