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[2026-09-10] · src Ortolá Leonard, Krolewski, Slepian, Greco, May, et al. (DESI Collaboration); arXiv:2609.09340 (2026-09-08)
Galaxy surveys have long used the two-point correlation function (clustering strength versus separation) and, more recently, the three-point function to constrain cosmology and galaxy bias. The connected four-point correlation function (4PCF) - the part of the 4-point statistic that is not just a product of lower-order correlations, i.e. genuinely irreducible four-galaxy information - has been computable in theory and tested on mock catalogs, but until now had not been measured on real observational data with any confidence. Using DESI Year 1 luminous red galaxies (0.4 < z < 1.1, with a higher-density 0.4 < z < 0.8 subsample also tested), this analysis finds a clear detection of the even-parity connected 4PCF at roughly 12 to 17σ in a full-sky analysis, robust across north/south hemisphere splits, redshift range, and sample-completeness cuts. A second check - cross-correlating spatially separated, largely independent patches, which removes leading-order mismatch between the data's covariance and the mock catalogs' - still finds ~15σ evidence, in some configurations at a cost to raw sensitivity.
This paper measures a detection, not yet cosmology from it: no parameters are fit here. What it establishes is that the 4PCF is now a usable observational statistic rather than a theoretical curiosity - the signal is strong enough, and robust enough to survey-geometry and pipeline choices, to build on. That opens three things at once: fitting cosmological-parameter and galaxy-bias models to a statistic orthogonal to the two- and three-point functions already in heavy use, hunting for the baryon acoustic oscillation feature's imprint in a fourth-order statistic where it has never been sought, and - probably nearer-term useful - a new, sensitive diagnostic for exactly the kind of mock-catalog-versus-data covariance mismatch that already limits how tightly DESI's lower-order analyses can quote their errors.
[2026-09-10] · src Ji, Joosten, Meziani, Pefkou; arXiv:2609.09318 (2026-09-08)
The proton and neutron have almost identical mass despite wildly different electromagnetic structure - a nearly-zero net charge distribution for the neutron versus the proton's well-measured ~0.84 fm charge radius - because nucleon mass is generated almost entirely by the strong force (via the QCD trace anomaly and the gluon field) rather than by quark rest mass, which contributes only a few percent. Mapping that mass-generating field directly requires a strong-interaction probe rather than an electromagnetic one, and the J/ψ - a compact color-singlet charm-anticharm dipole - couples to the proton's gluon field almost exclusively, making near-threshold J/ψ photoproduction (recently measured with much improved precision at Jefferson Lab) a comparatively clean handle on it. The authors combine those photoproduction results with existing quark-sector (charge and mass distribution) data to extract the color field's spatial distribution, reporting an overall "strong-interaction" radius of 0.94 ± 0.09 fm - nominally larger than both the charge radius and the (smaller) mass radius, though the gap over the charge radius is only about as big as its own combined uncertainty.
This is a theoretical extraction from already-published data using an established sum-rule framework, not a new experimental technique or a dramatic shift in a number - hence incremental rather than new - but it puts a first concrete, falsifiable figure on a question that previously had no operational answer: what does "the size of a nucleon" even mean once you ask the strong force rather than electromagnetism? Given how little of nucleon mass actually comes from quark rest mass, a spatial map - even a rough one, at one combined sigma from the charge radius - of the field responsible for the rest is a more useful target for lattice QCD to check against than another sum rule with no accompanying number.
[2026-09-10] · src Shuvo, Meyer, Laha, Roychowdhury, Sadaula, Clarke, Peters, Begelman, Georganopoulos, Mbarek, Hankla, Philippov, Sridhar; arXiv:2609.09539 (2026-09-08)
1ES 1927+654 is the changing-look AGN that famously lost and then rapidly rebuilt its X-ray corona in 2018, and has been watched closely ever since. Since a renewed X-ray brightening beginning mid-2022, this team's combined VLBA imaging and multi-band, time-resolved VLA monitoring shows it transitioning from a radio-quiet, non-jetted state to a radio-loud AGN with a bipolar, GHz-peaked jet - the spectral signature of a young, compact jet. For the first time during an active jet-formation episode, the team detects linear polarization, appearing above ~3 GHz with fractional polarization climbing from ~0.2% to ~6% as frequency increases; no circular polarization is seen at any epoch. Across 2026 the polarization angle (EVPA) executes a smooth, coherent rotation of about 137° over roughly 81 days while the source's total radio intensity stays flat, then partially swings back - the signature of an organized disturbance propagating through the compact emitting region rather than a random turbulent wander.
Jets are usually studied either fully formed, long after launch, or in simulation; this is a rare case of catching one being born, with polarimetry sensitive enough to trace how its magnetic field organizes while that happens rather than after the fact. A smooth, coherent EVPA rotation argues for an ordered field early in the jet's life rather than a disordered, turbulent one, which bears on jet-launching models generally. One rotation event in one source does not decide whether the launching mechanism here is magnetically dominated (Blandford-Znajek) or disk-driven - the follow-up monitoring this group is positioned to keep collecting on an already-instrumented, still-evolving jet is what would actually settle that.
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[2026-09-10] · src —
Alto takes today's slot — three days since its last session is the longest gap of the three instruments right now, and trumpet went yesterday, so the two chops-dependent instruments don't land back to back. With no method book chosen yet, the assignment stays inside the brief's placeholder: long tones, overtones, a scale pattern, nothing invented. Today's fundamental is low G, continuing the upward semitone climb the survey has held since it passed E♭, and both the warmup shape and the musical-target pattern continue their own second circuits — a diminuendo taper after last time's held tone, and the widest interval skip tried yet.
5 minutes: long tones on low G and G♯, four counts steady at f then a controlled taper to nothing over the next four counts, quarter=60, eight full counts per note. The target is a decay that stays centered in pitch all the way to silence rather than going flat or breathy as the air runs out — the release half of breath support, last tested on 08-29 and not since.
Overtone series from fundamental low G: voice up through G–G–D–G–B using only the low G fingering, changing partials with throat and voicing, not embouchure — the same method as every prior session, now a ninth semitone higher than where the climb started. Success criterion: three clean ascents in a row, each partial speaking immediately at a steady dynamic, no pinch or pitch smear at the change, and the fundamental still centered after dropping back down each time.
G major scale, one octave, in broken sixths (1-6-2-7-3-8 through the scale) rather than the thirds, fourths or fifths this survey has already broken up — the widest skip tried yet, wide enough that each pair spans most of the octave rather than sitting inside it. Shape it as a phrase: lean into the upper note of each pair, taper into the one that follows it, rather than playing the pattern metronomically.
Stop the moment the taper loses its center — going flat or breathy before it reaches silence — or an overtone needs a jaw shove or throat squeeze to speak. Both are fatigue standing in for support, and reps past that point train the substitute instead of the real thing.
[2026-09-10] · src —
hearLee Konitz — Subconscious-Lee · Tidal · Spotify
Konitz wrote this contrafact of "What Is This Thing Called Love" with Lennie Tristano in 1949, and it's a fair specimen of the whole Tristano school's melodic habit: reaching for the next idea by leap rather than by step, where the more chromatic bebop mainstream of the same years mostly ran lines. Today's musical target asks for exactly that shape at a much smaller, more mechanical scale — a scale broken into skips wide enough that the ear has to track where the line actually is rather than where a stepwise run would predict, the same demand Konitz's phrasing makes on a listener here across a whole improvised chorus.