Wed·Aug 3, 2022Wednesday·August 3, 2022

1. 01*

   BFB conditions on a class of symmetry constrained 3HDM

   Rafael Boto🇵🇹 · Jorge C. Romão🇵🇹 · João P. Silva🇵🇹

   We study the bounded from below (BFB) conditions on a class of three Higgs doublet models (3HDM) constrained by the symmetry groups U(1)xU(1), U(1)xZ2 and Z2xZ2. These constraints must be implemented on both the neutral (BFB-n) and charged (BFB-c) directions. The exact necessary and sufficient BFB conditions are unknown in the Z2xZ2 case. We develop a general strategy using lower bounds to find sufficient conditions for BFB-n and BFB-c and apply it to these symmetries. In addition, we investigate the concern that the use of safe sufficient conditions can ignore valid points which would yield distinct physical consequences. This is done by performing a full phenomenological simulation of the U(1)xU(1) and U(1)xZ2 models, where exact necessary and sufficient BFB conditions are possible. We look specifically at the points allowed by exact solutions but precluded by safe lower bounds. We found no evidence of remarkable new effects, partly reassuring the use of the lower bounds we propose here, for those potentials where no exact necessary and sufficient BFB conditions are known.

   hep-phPRD(2022)·21 citations
2. 02*

   Unitarity Bounds on the Massive Spin-2 Particle Explanation of Muon $g-2$ Anomaly

   Da Huang🇨🇳 · Chao-Qiang Geng🇨🇳 · Jiajun Wu🇨🇳

   Motivated by the long-standing discrepancy between the Standard Model prediction and the experimental measurement of the muon magnetic dipole moment, we have recently proposed to interpret this muon $g-2$ anomaly in terms of the loop effect induced by a new massive spin-2 field $G$. In the present paper, we investigate the unitarity bounds on this scenario. We calculate the $s$-wave projected amplitudes for two-body elastic scatterings of charged leptons and photons mediated by $G$ at high energies for all possible initial and final helicity states. By imposing the condition of the perturbative unitarity, we obtain the analytic constraints on the charged-lepton-$G$ and photon-$G$ couplings. We then apply our results to constrain the parameter space relevant to the explanation of the muon $g-2$ anomaly.

   hep-phEPJC(2024)·3 citations
3. 03*

   Bremsstrahlung from Neutrino Scattering via Magnetic Dipole Moments

   Konstantin Asteriadis🇺🇸 · Alejandro Quiroga Triviño🇹🇼 · Martin Spinrath🇹🇼

   In this paper we discuss bremsstrahlung induced by neutrino scattering. This process should exist since neutrinos are expected to couple to photons via magnetic dipole and transition moments. These moments are loop-induced and tiny in the Standard Model with neutrino masses but could be significantly enhanced in extended theories. As concrete example we study the scattering of the two largest neutrino fluxes on earth, solar neutrinos and Cosmic Neutrino Background (CNB). It is tempting to consider this as a potential signature for CNB searches but it turns out that the signal is extremely small and unlikely to be observed.

   hep-phastro-ph.COInt.J.Mod.Phys.A(2023)·12 citations
4. 04*

   Holographic imaginary potential of a quark antiquark pair in the presence of gluon condensation

   Sara Tahery🇨🇳 · Xurong Chen🇨🇳 · Zi-qiang Zhang🇨🇳

   For a moving heavy quark antiquark ($Q\bar{Q}$) in a quark gluon plasma (QGP), we use gauge/gravity duality to study both real and imaginary parts of the potential (Re$V_{Q\bar{Q}}$ and Im$V_{Q\bar{Q}}$ respectively) in a gluon condensate (GC) theory. The complex potential is derived from the Wilson loop by considering the thermal fluctuations of the worldsheet of the Nambu-Goto holographic string. We calculate Re$V_{Q\bar{Q}}$ and Im$V_{Q\bar{Q}}$ in both cases where the axis of the moving $Q\bar{Q}$ pair is transverse and parallel with respect to its direction of movement in the plasma. Using the renormalization scheme for the Re$V_{Q\bar{Q}}$ , we find that the inclusion of GC increases the dissociation length while rapidity has the opposite effect. While for the Im$V_{Q\bar{Q}}$ , we observe that by considering the effect of GC, the Im$V_{Q\bar{Q}}$ is generated for larger distance thus decreasing quarkonium dissociation, while rapidity has opposite effect. In particular, as the value of GC decreases in the deconfined phase, the Im$V_{Q\bar{Q}}$ is generated for smaller distance thus enhancing quarkonium dissociation, and at high temperatures it is nearly not modified by GC, consistent with previous findings of the entropic force.

   hep-phhep-thJHEP(2023)·11 citations
5. 05*

   Mechanical structure of a spin-1 particle

   June-Young Kim🇩🇪 · Bao-Dong Sun🇨🇳 · Dongyan Fu🇨🇳 · Hyun-Chul Kim🇰🇷

   We investigate the mechanical structure of a spin-1 particle. Introducing three different frameworks, i.e., the three-dimensional (3D) Breit frame, the two-dimensional (2D) Breit frame, and the 2D infinite momentum frame (equivalently the two-dimensional Drell-Yan frame), we scrutinize the 2D and 3D energy-momentum tensor (EMT) distributions in these frames. We first derive the EMT distributions in the 2D Breit frame by performing the Abel transformation. The mass distribution in the 2D Breit frame contains an additional monopole contribution induced geometrically. The pressure distribution in the 2D Breit frame also gets an induced monopole structure. When the Lorentz boost is carried out, the mass distribution in the 2D infinite-momentum frame acquires the induced dipole term. Similarly, we also have the induced dipole contributions to the pressure and shear-force densities. We visualize the 2D mass distributions when the spin-1 particle is polarized along the $x$- and $z$-axes. We observe that the 2D mass distribution in the infinite momentum frame exhibit clearly the induced dipole structure when the spin-1 particle is polarized along the $x$-axis. We also discuss the strong force fields inside a polarized spin-1 particle.

   hep-phPRD(2023)·27 citations
6. 06*

   Quintessential Axions

   Jihn E. Kim🇰🇷

   I review the dark energy solutions by a very light pseudoscalar called "quintessential axion". For the explicit breaking terms, we consider both the global anomaly U(1)${}_{\mathrm{global}}\times$SU(2)${}_W^2$ and the potential $\Delta V$. At the field theory level, we will present a strategy for picking up one such pseudoscalar among plenty of pseudoscalars. At string level, numerous antisymmetric tensor fields are pseudoscalars. Including these, we present a confining force example via a $Z_{12-I}$ orbifold compactification of SO(32) heterotic string. In addition, we also aim to draw attention on almost massless mesons of confining nonabelian gauge group, which can be another motivation for introducing an additional confining force, to explain dark energy as the vacuum energy of these mesons.

   hep-phhep-th1 citation
7. 07*

   Quantum scale invariance in gauge theories and applications to muon production

   Matthias Weißwange🇩🇪 · Dumitru M. Ghilencea🇷🇴 · Dominik Stöckinger🇩🇪

   We discuss quantum scale invariance in (scale invariant) gauge theories with both ultraviolet (UV) and infrared (IR) divergences. Firstly, their BRST invariance is checked in two apparently unrelated approaches using a scale invariant regularisation (SIR). These approaches are then shown to be equivalent. Secondly, for the Abelian case we discuss both UV and IR quantum corrections present in such theories. We present the Feynman rules in a form suitable for offshell Green functions calculations, together with their one-loop renormalisation. This information is then used for the muon production cross section at one-loop in a quantum scale invariant theory. Such a theory contains not only new UV poles but also IR poles. While the UV poles bring new quantum corrections (in the form of counterterms), finite or divergent, that we compute, it is shown that the IR poles do not bring new physics. The IR quantum corrections, both finite and divergent, cancel out similarly to the way the IR poles themselves cancel in the traditional approach to IR divergences (in the cross section, after summing over virtual and real corrections). Hence, the evanescent interactions induced by the scale-invariant analytical continuation of the SIR scheme do not affect IR physics, as illustrated at one-loop for the muon production ($e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$) cross section.

   hep-phgr-qchep-thPRD(2023)·15 citations
8. 08*

   How arbitrary are perturbative calculations of the electroweak phase transition?

   Peter Athron🇨🇳 · Csaba Balazs🇦🇺 · Andrew Fowlie🇨🇳 · Lachlan Morris🇦🇺 · Graham White🇯🇵 · Yang Zhang🇨🇳

   We investigate the extent to which perturbative calculations of the electroweak phase transition are arbitrary and uncertain, owing to their gauge, renormalisation scale and scheme dependence, as well as treatments of the Goldstone catastrophe and daisy diagrams. Using the complete parameter space of the Standard Model extended by a real scalar singlet with a ${\mathbb{Z}}_2$ symmetry as a test, we explore the properties of the electroweak phase transition in general $R_{\xi }$ and covariant gauges, OS and $\overline{\text{MS}}$ renormalisation schemes, and for common treatments of the Goldstone catastrophe and daisy diagrams. Reassuringly, we find that different renormalisation schemes and different treatments of the Goldstone catastrophe and daisy diagrams typically lead to only modest changes in predictions for the critical temperature and strength of the phase transition. On the other hand, the gauge and renormalisation scale dependence may be significant, and often impact the existence of the phase transition altogether.

   hep-phJHEP(2023)·62 citations
9. 09*

   A note on quark and gluon energy-momentum tensors

   Taushif Ahmed🇮🇹 · Long Chen🇨🇳 · Michał Czakon🇩🇪

   We discuss the constraints on quark and gluon energy-momentum tensors in QCD that follow from the requirement of Renormalisation-Group invariance of the traces of these operators. Our study covers the most general form of the latter traces, while the energy-momentum tensors themselves are only subjected to very mild constraints. We derive Renormalisation-Group equations for the two finite independent functions of the strong coupling constant and renormalisation scale of minimal subtraction which completely define the energy-momentum tensors. We demonstrate that previously proposed definitions of the renormalized quark and gluon energy-momentum tensors are special cases of our results assuming no explicit dependence on the renormalisation scale. Finally, we present $\overline{\mathrm{MS}}$-renormalised quark and gluon energy-momentum tensors at four-loop order.

   hep-phhep-lathep-thJHEP(2023)·12 citations
10. 10*

    Opportunities with ultra-soft photons: Bremsstrahlung from stopping

    Sohyun Park🇨🇭

    We compute the spectra of bremsstrahlung photons for different stopping scenarios which give rise to different initial charge-rapidity distributions. In the light of novel experimental opportunities that may arise with a new heavy-ion detector ALICE-3 at the CERN LHC, we discuss how to discriminate between these stopping scenarios and how to disentangle bremsstrahlung photons from other photon sources.

    hep-phhep-exnucl-thActa Phys.Polon.Supp.(2023)·1 citation
11. 11*

    QCD anatomy of photon isolation

    Thomas Becher🇨🇭 · Samuel Favrod🇨🇭 · Xiaofeng Xu🇨🇭

    To separate the energetic photons produced in hard scattering processes from those from other sources, measurements impose isolation requirements which restrict the hadronic radiation inside a cone around the photon. In this paper, we perform a detailed factorization analysis of the QCD effects associated with photon isolation. We show that for small cone radius $R$, photon isolation effects can be captured by a fragmentation function describing the decay of a parton into a photon accompanied by hadronic radiation. We compute this fragmentation function for different isolation criteria and solve the associated renormalization group equations to resum logarithms of $R$. For small isolation energy, the cone fragmentation function factorizes further, into collinear functions describing energetic quarks and gluons near the cone boundary and functions encoding their soft radiation emitted into the cone. Based on this factorization we also resum the non-global logarithms of the ratio of the photon energy and the isolation energy, so that we control all logarithmically enhanced terms in the cross section. Finally, we provide a simple formula to convert NNLO cross section results from smooth-cone isolation to fixed-cone isolation.

    hep-phJHEP(2023)·9 citations
12. 12*

    Probing hyperon CP violation from charmed baryon decays

    Jian-Peng Wang🇨🇳 · Fu-Sheng Yu🇨🇳

    CP violation (CPV) in the baryon sectors has not yet been established experimentally. In this work, we propose to search for the hyperon CPV through the Cabibbo-favored charm-baryon decaying processes involving a hyperon in the final states, such as ${\Lambda }_c^{+}\to {\Lambda }^0{\pi }^{+},{\Lambda }^0\to p{\pi }^{-}$. The CPV of the hyperon decays are purely revealed in these chain processes, since the CPV in the Cabibbo-favored charm decays are vanishing in the Standard Model (SM). The hyperons are polarized in the weak charm decays, so that we can measure the Lee-Yang asymmetric parameter $\alpha$ by the angular distributions, and then can measure the $\alpha$-induced CPV. It can be found that it is accessible for Belle II and LHCb to reach the SM prediction of the hyperon CPV in the near future.

    hep-phhep-exPLB(2024)·22 citations
13. 13*

    Searching for Ultra-Light Axions with Twisted Cavity Resonators of Anyon Rotational Symmetry with Bulk Modes of Non-Zero Helicity

    J. F. Bourhill🇦🇺 · E. C. I. Paterson🇦🇺 · M. Goryachev🇦🇺 · M. E. Tobar🇦🇺

    Möbius-ring resonators stem from a well-studied and fascinating geometrical structure that features a one-sided topology; the Möbius strip, and have been shown to exhibit fermion rotational symmetry with respect to a ring resonator with no twist (which exhibits boson rotational symmetry) (see PhysRevLett.101.247701). Here, we present a new type of resonator through the formation of twisted hollow structures using equilateral triangular cross-sections, which leads to the realization of a cavity with anyon rotational symmetry. Unlike all previous cavity resonators, the anyon resonator permits the existence of bulk resonant modes that exhibit non-zero electromagnetic helicity in vacuo, with a non-zero overlap of the electric and magnetic mode eigenvectors, $\int {\mathbf{E}}_p\cdot {\mathbf{B}}_{p}d\tau$, integrated over the cavity volume. In the upconversion limit, we show that these non-zero helical modes couple naturally to ultra-light dark matter axions within the bandwidth of the resonator by adding amplitude-modulated sidebands through the axion-photon chiral anomaly. Thus, we show a sensitive ultra-light dark matter experiment may be realized by implementing such a resonator in an ultra-stable oscillator configuration and searching for signals in the Fourier spectrum of amplitude fluctuations. This removes the typical requirement for an external magnetic field and therefore permits the use of superconducting materials to reduce surface losses and enhance sensitivity to axions.

    hep-phastro-ph.IMphysics.ins-detquant-phPRD(2023)·29 citations
14. 14*

    Monojet signatures from gluino and squark decays

    Iñaki Lara🇵🇱 · Trygve Buanes🇳🇴 · Rafał Masełek🇵🇱 · Mihoko M. Nojiri🇯🇵 · Krzysztof Rolbiecki🇵🇱 · Kazuki Sakurai🇵🇱

    We study the monojet and dijet channels at the LHC as a tool for searching for squarks and gluinos. We consider two separate R-parity conserving supersymmetric scenarios. In the first scenario we postulate a large mass hierarchy between squarks ($\tilde{q}$) and winos ($\tilde{W}$), and wino-like neutralino is assumed to be the lightest supersymmetric particle (LSP). The associated squark-wino production, $pp\to \tilde{q}\tilde{W}$, then leads to a monojet-like signature, where the high $p_T$ jet is originated from the squark decay, $\tilde{q}\to q+\tilde{W}$. We demonstrate that this associated production, as well as the $pp\to \tilde{W}\tilde{W}+\mathrm{jets}$ production, have a significant impact on the exclusion limit in the squark-neutralino mass plane. The second scenario postulates that the lighter of the squark and gluino is only a few GeV heavier than the LSP neutralino. The associated squark-gluino production, $pp\to \tilde{q}\tilde{g}$, then leads to a distinctive monojet signature, where the high $p_T$ jet is produced from the decay of the heavier coloured particle into the lighter one ($\tilde{q}\to q+\tilde{g}$ for $m_{\tilde{q}}>m_{\tilde{g}}$ and $\tilde{g}\to q+\tilde{q}$ for $m_{\tilde{g}}>m_{\tilde{q}}$). The lighter coloured particle is effectively regarded as an invisible particle since the decay products are soft due to the approximate mass degeneracy. We recast existing monojet and dijet analyses and find a non-trivial exclusion limit in the squark-gluino mass plane in this scenario.

    hep-phhep-exJHEP(2022)·8 citations
15. 15*

    Light Axion Emission and the Formation of Merging Binary Black Holes

    Djuna Croon🇬🇧 · Jeremy Sakstein🇺🇸

    We study the impact of stellar cooling due to light axion emission on the formation and evolution of black hole binaries, via stable mass transfer and the common envelope scenario. We find that in the presence of light axion emission, no binary black hole mergers are formed with black holes in the lower mass gap (${\mathrm{M}}_{\mathrm{BH}}<4{\mathrm{M}}_{\odot }$) via the common envelope formation channel. In some systems, this happens because axions prevent Roche lobe overflow. In others, they prevent the common envelope from being ejected. Our results apply to axions with couplings $g_{a\gamma }\gtrsim 10^{-10}\mathrm{Ge}{\mathrm{V}}^{-1}$ (to photons) or ${\alpha }_{ae}\gtrsim 10^{-26}$ (to electrons) and masses $m_a\ll 10\mathrm{keV}$. Light, weakly coupled particles may therefore apparently produce a mass gap $2{\mathrm{M}}_{\odot }<{\mathrm{M}}_{\mathrm{BH}}<4{\mathrm{M}}_{\odot }$ in the LIGO/Virgo/KAGRA data, when no mass gap is present in the stellar remnant population.

    ↳ astro-ph.HEastro-ph.COastro-ph.SRgr-qc+1PRD(2023)·3 citations
16. 16*

    CP-violation search with T2K data

    J. G. Walsh🇺🇸

    The T2K experiment is a long-baseline neutrino oscillation experiment which uses ${\nu }_{\mu }$ and ${\bar{\nu }}_{\mu }$ beams to constrain CP-violating effects in a 3-flavor PMNS neutrino mixing model. Through ${\nu }_{\mu }\to {\nu }_e$ and ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_e$ appearance channels, T2K is sensitive to CP-violating effects in neutrino mixing. An excess of ${\nu }_e$ candidates in the $\nu$-beam mode is observed when compared to the CP conserving cases. T2K finds a best fit value of ${\delta }_{\mathrm{CP}}=-1.97_{-0.70}^{+0.97}$ using Feldman-Cousins corrected intervals and excludes CP-conserving values of ${\delta }_{\mathrm{CP}}$ of $0$ and $\pi$ at the 90% CL. $J_{\mathrm{CP}}=0$ is also excluded at 2$\sigma$ when using a flat prior in ${\delta }_{\mathrm{CP}}$, favoring negative values.

    ↳ hep-exhep-ph5 citations
17. 17*

    Directed flow of $\Lambda$ in high-energy heavy-ion collisions and $\Lambda$ potential in dense nuclear matter

    Yasushi Nara🇯🇵 · Asanosuke Jinno🇯🇵 · Koichi Murase🇯🇵 · Akira Ohnishi🇯🇵

    We investigate the sensitivity of the $\Lambda$ directed flow to the $\Lambda$ potential in mid-central Au + Au collisions at $\sqrt{s_{NN}}\approx 3.0$--$30$ GeV. The $\Lambda$ potential obtained from the chiral effective field theory ($\chi$EFT) is used in a microscopic transport model, a vector version of relativistic quantum molecular dynamics (RQMDv). We find that the density-dependent $\Lambda$ potentials, obtained from the $\chi$EFT assuming weak momentum dependence of the potential, reproduce the rapidity and the beam-energy dependence of the $\Lambda$ directed flow measured by the STAR collaboration in the Beam Energy Scan program. Although the $\Lambda$ directed flow is insensitive to the density dependence of the potential, it is susceptible to the momentum dependence. We also show that a hydrodynamics picture based on the blast-wave model predicts a similarity of the proton, $\Lambda$, and $\Xi$ directed flows, but the directed flow of $\Omega$ baryons slightly deviates from other baryons. We also show that the quark coalescence predicts different rapidity dependence of the directed flows for hyperons. These investigations suggest that measurements of a wide range of the rapidity dependence of the directed flow of hyperons may provide important information about the properties of hot and dense matter created in high-energy heavy-ion collisions.

    ↳ nucl-thhep-phnucl-exPRC(2022)·44 citations
18. 18*

    Unification of elementary forces in gauge SL(2N,C) theories

    J.L. Chkareuli🇬🇪

    We argue that the gauge $SL(2N,C)$ theories may point to a possible way where the known elementary forces, including gravity, could be consistently unified. Remarkably, while all related gauge fields are presented in the same adjoint multiplet of the $SL(2N,C)$ symmetry group, the tensor field submultiplet providing gravity can be naturally suppressed in the weak-field approach developed for accompanying tetrad fields. As a result, the whole theory turns out to effectively possess the local $SL(2,C)\times SU(N)$ symmetry so as to naturally lead to the $SL(2,C)$ gauge gravity, on the one hand, and the $SU(N)$ grand unified theory, on the other. Since all states involved in the $SL(2N,C)$ theories are additionally classified according to their spin values, many possible $SU(N)$ GUTs - including the conventional one-family $SU(5)$ theory - appear not to be relevant for the standard $1/2$ spin quarks and leptons. Meanwhile, the $SU(8)$ grand unification for all three families of composite quarks and leptons that stems from the $SL(16,C)$ theory seems to be of special interest that is studied in some detail.

    ↳ hep-thhep-phPLB(2022)·4 citations
19. 19*

    Multitension strings in high-resolution U(1)$\times$U(1) simulations

    J. R. C. C. C. Correia🇵🇹 · C. J. A. P. Martins🇵🇹

    Topological defects are a fossil relic of early Universe phase transitions, with cosmic strings being the best motivated example. While in most cases one studies Nambu-Goto or Abelian-Higgs strings, one also expects that cosmologically realistic strings should have additional degrees of freedom in their worldsheets, one specific example being superstrings from Type IIB superstring theory. Here we continue the scientific exploitation of our recently developed multi-GPU field theory cosmic strings code to study the evolution of U(1)$\times$U(1) multitension networks, which are a numerically convenient proxy: these contain two lowest-tension strings networks able to interact and form bound states, providing a convenient first approximation to the behaviour expected from cosmic superstrings. (...) We rely on the largest field theory simulations of this model so far, specifically $4096^3$, $\Delta x=0.5$ boxes. We present robust evidence of scaling for the lightest strings, measured through a complete and self-consistent set of correlation length and velocity diagnostics. We also find a linearly growing average length of the bound state segments, consistent with a scaling behaviour. (In previously reported lower-resolution simulations, such behaviour had only been identified with carefully engineered initial conditions, rich in those segments.) Finally, while we see no evidence of a large population of bound states forming at early stages of the network evolution, we do present tentative evidence for an asymptotic constant value of the fraction of bound states, with this value being different in the radiation and the matter eras. Our work demonstrates that our GPU-accelerated field theory code can by successfully extended beyond the simple Abelian-Higgs approximation, and enables future detailed studies of realistic string networks and of their observational signatures.

    ↳ astro-ph.COgr-qchep-phphysics.comp-phPRD(2022)·11 citations
20. 20*

    Unveiling cosmological information on small scales with line intensity mapping

    Sarah Libanore🇮🇱 · Caner Unal🇮🇱 · Debanjan Sarkar🇨🇦 · Ely D. Kovetz🇮🇱

    One of the toughest challenges in modern cosmology is to probe the small scales $k\sim 0.5$Mpc${}^{-1}$ in the matter power spectrum and clustering. We show that such small scales will be accessible via upcoming line-intensity mapping surveys, with carbon monoxide (CO) emission from star-forming galaxies at high redshifts as an example. While these galaxies cannot be individually detected and the two-point correlations of the intensity fluctuation maps is not accessible at these scales, the voxel intensity distribution (VID) of the highly non-Gaussian intensity maps is sensitive to the integrated emission from faint sources. As we describe, the main limitations are due to uncertainties related with the halo mass function and the CO emission model. We show that via the VID, high-redshift next-generation experiments can probe deviations from $\Lambda$CDM of order unity, while stage-3 experiments will be able to probe deviations as small as $\lesssim 10\%$ at least up to $k\sim 10$Mpc${}^{-1}$.

    ↳ astro-ph.COhep-phPRD(2022)·17 citations
21. 21*

    Neutrino Masses and Helicities

    J.W. Moffat🇨🇦

    Models of neutrinos and their mass generation by self-energy radiative corrections are formulated in an ultraviolet complete quantum field theory (UCQFT). A model of the three flavors of neutrinos as Majorana fermions is developed as the minimal model. A model incorporating an SU(2) singlet sterile neutrino can also be formulated.

    ↳ physics.gen-phhep-ph1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.