Mon·Oct 14, 2019Monday·October 14, 2019

1. 01*

   Explaining the AMS positron excess via Right-handed Neutrinos

   Farinaldo S. Queiroz🇧🇷 · Clarissa Siqueira🇧🇷

   We have witnessed in the past decade the observation of a puzzling cosmic-ray excess at energies larger than $10$ GeV. The AMS-02 data published this year has new ingredients such as the bump around $300$ GeV followed by a drop at $800$ GeV, as well as smaller error bars. Adopting the background used by the AMS-02 collaboration in their analysis, one can conclude that previous explanations to the new AMS-02 such as one component annihilating and decaying dark matter as well as pulsars seem to fail at reproducing the data. Here, we show that in the right-handed neutrino portal might reside the answer. We discuss a decaying two-component dark matter scenario where the two-body decay products are right-handed neutrinos that have their decay pattern governed by the type I seesaw mechanism. This setup provides a very good fit to data, for example, for a conservative approach including just statistical uncertainties leads to ${\chi }^2/d.o.f\sim 2.3$ for $m_{D{M}_1}=2150$ GeV with ${\tau }_1=3.78\times 10^{26}$ s and $m_{D{M}_2}=300$ with ${\tau }_2=5.0\times 10^{27}$ s for $M_N=10$ GeV, and, in an optimistic case, including systematic uncertainties, we find ${\chi }^2/d.o.f\sim 1.12$, for $M_N=10$ GeV, with $m_{D{M}_1}=2200$ GeV with ${\tau }_1=3.8\times 10^{26}$ s and $m_{D{M}_2}=323$ GeV with ${\tau }_2=1.68\times 10^{27}$ s.

   hep-phastro-ph.HEPRD(2020)·4 citations
2. 02*

   Probing the Pomeron spin-flip with Coulomb-nuclear interference

   B. Z. Kopeliovich🇨🇱 · M. Krelina🇨🇱

   Brand-new high-precision data for single-spin asymmetry $A_N(t)$ in small angle elastic $pp$ scattering from the fixed target experiment HJET at BNL at $E_{lab}=100$ and $255\text{mbox}GeV$, as well as high energy STAR measurements at $\sqrt{s}=200\text{mbox}GeV$, for the first time allowed to determine the spin-flip to non-flip ratio $r_5(t)$ in a wide energy range. We introduced an essential modification in the Coulomb-nuclear interference (CNI) mechanism, missed in previous analyses. It can be formulated either as a modification of the Coulomb phase, which is much larger for the spin-flip compared with non-flip amplitudes, or as absorptive corrections to the electromagnetic interaction of hadrons. The Regge analysis singles out the Pomeron contribution to the spin-flip amplitude, which steeply rises with energy. We found the spin-flip to non-flip ratio of the Pomeron amplitudes to be nearly $-10\%$, steeply rising with energy in accordance with theoretical expectations.

   hep-ph4 citations
3. 03*

   Extraction of DVCS form factors with uncertainties

   Kresimir Kumericki🇭🇷

   We discuss recent attempts to extract deeply virtual Compton scattering form factors with emphasis on their uncertainties, which turn out to be most reliably provided by method of neural networks.

   hep-ph8 citations
4. 04*

   Dodelson-Widrow Mechanism In the Presence of Self-Interacting Neutrinos

   André de Gouvêa🇺🇸 · Manibrata Sen🇺🇸 · Walter Tangarife🇺🇸 · Yue Zhang🇺🇸

   keV-scale gauge-singlet fermions, allowed to mix with the active neutrinos, are elegant dark matter (DM) candidates. They are produced in the early universe via the Dodelson-Widrow mechanism and can be detected as they decay very slowly, emitting X-rays. In the absence of new physics, this hypothesis is virtually ruled out by astrophysical observations. Here, we show that new interactions among the active neutrinos allow these sterile neutrinos to make up all the DM while safely evading all current experimental bounds. The existence of these new neutrino interactions may manifest itself in next-generation experiments, including DUNE.

   hep-phastro-ph.COPRL(2020)·125 citations
5. 05*

   The viability of the 3+1 neutrino model in the supernova neutrino process

   Heamin Ko🇰🇷 · Dukjae Jang🇰🇷 · Motohiko Kusakabe🇨🇳 · Myung-Ki Cheoun🇰🇷

   Adopting the 3+1 neutrino mixing parameters by the IceCube and shortbase line experiments, we investigate the sterile-active neutrino oscillation effects on the supernova neutrino process. For the sterile neutrino (${\nu }_s$), we study two different luminosity models. First, we presume that the ${\nu }_s$ does not interact with other particles through the standard interactions apart from the oscillation with the active neutrinos. Second, we consider that ${\nu }_s$ can be directly produced by ${\nu }_e$ scattering with matter. In both cases, we find that the pattern of neutrino oscillations can be changed drastically by the ${\nu }_s$ in supernova environments. Especially multiple resonances occur, and consequently affect thermal neutrino-induced reaction rates. As a result, ${}^7$Li, ${}^7$Be, ${}^{11}$B, ${}^{11}$C, ${}^{92}$Nb, ${}^{98}$Tc and ${}^{138}$La yields in the $\nu$-process are changed. Among those nuclei, ${}^7$Li and ${}^{11}$B yields can be constrained by the analysis of observed SiC X grains. Based on the meteoritic data, we conclude that the second model can be allowed while first model is excluded. The viability of the second model depends on the sterile neutrino temperature and the neutrino mass hierarchy.

   hep-phastro-ph.SRnucl-thApJ(2020)·7 citations
6. 06*

   Gravitational waves from chiral phase transition in a conformally extended standard model

   Mayumi Aoki (Kanazawa U.)🇯🇵 · Jisuke Kubo (Heidelberg, Max Planck Inst. & Toyama U.)🇩🇪

   The gravitational wave (GW) background produced at the cosmological chiral phase transition in a conformal extension of the standard model is studied. To obtain the bounce solution of coupled field equations we implement an iterative method. We find that the corresponding $O(3)$ symmetric Euclidean action $S_3$ divided by the temperature $T$ has a simple behavior near the critical temperature $T_C$: $S_3/T\propto (1-T/T_C{)}^{-\gamma }$, which is subsequently used to determine the transition's inverse duration $\beta$ normalized to the Hubble parameter $H$. It turns out that $\beta /H\gtrsim 10^3$, implying that the sound wave period ${\tau }_{\text{sw}}$ as an active GW source, too, can be much shorter than the Hubble time. We therefore compute ${\tau }_{\text{sw}}H$ and use it as the reduction factor for the sound wave contribution. The signal-to-noise ratio (SNR) for Deci-Hertz Interferometer Gravitational Wave Observatory (DECIGO) and Big Bang Observer (BBO) is evaluated, with the result: SNR${}^{\text{DECIGO}}\lesssim 1.2$ and SNR${}^{\text{BBO}}\lesssim 12.0$ for five years observation, from which we conclude that the GW signal predicted by the model in the optimistic case could be detected at BBO.

   hep-phJCAP(2020)·39 citations
7. 07*

   Global study of effective Higgs portal dark matter models using GAMBIT

   Ankit Beniwal (for the GAMBIT Collaboration)🇧🇪

   In this proceeding, we present frequentist and Bayesian results from a global fit of effective vector and Majorana fermion Higgs portal dark matter (DM) models using the $\mathsf{GAMBIT}$ software. We systematically explore the parameter space of these models using advanced sampling techniques to simultaneously satisfy the observed DM abundance, Higgs invisible decay, and indirect and direct detection limits. In addition, we take account of a set of nuisance parameters arising from Standard Model, nuclear physics, DM halo and velocity distribution. For the vector DM model viable solutions are found at low and high vector masses. The Majorana fermion model requires a strong preference for a CP-odd, parity-violating coupling which leads to a momentum-suppression of the DM-nucleon cross-section. All of our results, samples and input files are publicly available via $\text{href}$.

   hep-phastro-ph.COPoS(2020)·2 citations
8. 08*

   Modified interactions in the top-quark electroweak sector: exploiting unitarity violating effects at the amplitude level to probe New Physics

   Fabio Maltoni🇧🇪 · Luca Mantani🇧🇪 · Ken Mimasu🇧🇪

   We present a broad study of collider processes that embed $2\to 2$ scattering amplitudes involving top quarks in the Electroweak sector. We parametrise the modified interactions using the Standard Model Effective Field Theory framework and discuss how the New Physics effects lead to unitarity violating behaviour at the amplitude level. For each scattering amplitude we compute the helicity amplitudes in the high energy limit paying special attention to the effects of the higher dimensional operators. We also discuss whether and to what extent the unitarity violating effects are retained in physical processes at colliders.

   hep-phPoS(2020)·2 citations
9. 09*

   Comparatively Light Extra Higgs States as Signature of SUSY $\mathrm{SO}(10)$ GUTs with 3rd Family Yukawa Unification

   Stefan Antusch🇨🇭 · Christian Hohl🇨🇭 · Vasja Susic🇨🇭

   We study $3$rd family Yukawa unification in the context of supersymmetric (SUSY) $\mathrm{SO}(10)$ GUTs and $\mathrm{SO}(10)$-motivated boundary conditions for the SUSY-breaking soft terms. We consider $\mu <0$ such that the SUSY loop-threshold effects enable a good fit to all third family masses of the charged Standard Model (SM) fermions. We find that fitting the third family masses together with the mass of the SM-like Higgs particle, the scenario predicts the masses of the superpartner particles and of the extra Higgs states of the MSSM: while the sparticles are predicted to be comparatively heavy (above the present LHC bound but within reach of future colliders), the spectrum has the characteristic feature that the lightest new particles are the extra MSSM Higgses. We show that this effect is rather robust with respect to many deformations of the GUT boundary conditions, but turns out to be sensitive to the exactness of top-bottom Yukawa unification. Nevertheless, with moderate deviations of a few percent from exact top-bottom Yukawa unification (stemming e.g.\ from GUT-threshold corrections or higher-dimensional operators), the scenario still predicts extra MSSM Higgs particles with masses not much above $1.5\mathrm{TeV}$, which could be tested e.g.\ by future LHC searches for ditau decays $H^0/A^0\to \tau \tau$. Finding the extra MSSM Higges before the other new MSSM particles could thus be a smoking gun for a Yukawa unified $\mathrm{SO}(10)$ GUT.

   hep-phJHEP(2020)·8 citations
10. 10*

    Identifying Exclusive Displaced Hadronic Signatures in the Forward Region of the LHC

    Xabier Cid Vidal🇪🇸 · Yuhsin Tsai🇺🇸 · Jose Zurita🇩🇪

    The LHCb detector provides accurate vertex reconstruction and hadronic particle identification, which make the experiment an ideal place to look for light long-lived particles (LLP) decaying into Standard Model (SM) hadrons. In contrast with the typical search strategy relying on energetic jets and a high multiplicity of tracks from the LLP decay, LHCb can identify LLPs in exclusive, specific hadronic final states. To illustrate the idea, we study the sensitivity of LHCb to an exotic Higgs decay $h\to SS$, followed by the displaced decay of GeV-scale scalars into charged kaons $S\to K^{+}{K}^{-}$. We show that the reconstruction of kaon vertices in narrow invariant mass windows can efficiently eliminate the combinatorial backgrounds from $B$-meson decays. While the same signal is extremely difficult to probe in the existing displaced jet searches at ATLAS/CMS, the LHCb search we propose can probe the branching ratio BR$(h\to SS)$ down to $0.1\%$ ($0.02\%$) level with $15$ ($300$) fb${}^{-1}$ of data. We also apply this projected bound to two scenarios with Higgs portal couplings, where the scalar mediator $S$ either couples to a) the SM quarks only, or b) to both quarks and leptons in the minimal flavor violation paradigm. In both scenarios we compare the reach of our proposed search with the expected constraints from ATLAS and CMS on the invisible Higgs width and with the constraints from rare B-decays studies at LHCb. We find that for 1 GeV $<m_S<$ 2 GeV and $0.5\mathrm{mm}\lesssim c\tau \lesssim 10$ mm our proposed search will be competitive with the ATLAS and CMS projections, while at the same time providing crucial information of the hadronic interactions of $S$, which can not be obtained from the {\it indirect} measurement of the Higgs invisible width.

    hep-phhep-exJHEP(2020)·24 citations
11. 11*

    The Heavy Quark Expansion for Inclusive Semileptonic Charm Decays Revisited

    Matteo Fael🇩🇪 · Thomas Mannel🇩🇪 · K. Keri Vos🇩🇪

    The Heavy Quark Expansion (HQE) has become an extremely powerful tool in flavor physics. For charm decays, where the expansion parameters ${\alpha }_s(m_c)$ and ${\Lambda }_{\mathrm{QCD}}/m_c$ are bigger than for bottom decays, it remains to be seen if the HQE can be applied with similar success. Nevertheless, to make optimal use of the plethora of data already available and coming in the near future, a better understanding of HQE for charm decays is crucial. This paper discusses in detail how the HQE for charm decays is set up, what is the role of four-quark (weak annihilation) operators and how this compares to the well understood bottom decays. Subtleties concerning radiative corrections and the charm mass scheme are briefly discussed. An experimental study of the relevant HQE hadronic matrix elements will then show if the HQE expansion for charm converges well enough. Besides serving as an important cross check for inclusive $B$ decays, in the end, this study might open the road for inclusive $|V_{cs}|$ and $|V_{cd}|$ extractions.

    hep-phhep-latJHEP(2019)·29 citations
12. 12*

    On the Measurement of Sachs Form Factors in Processes without and with Proton Spin Flip

    M.V. Galynskii🇧🇾

    The physical meaning of the decomposition of the Rosenbluth formula into two terms containing only squares of Sachs form factors has been established. A new method has been proposed for their independent measurement in the $e\vec{p}\to e\vec{p}$ elastic process when the initial proton at rest is fully polarized along the direction of motion of the final proton.

    hep-phhep-exJETP Lett.(2019)·6 citations
13. 13*

    Medium-Induced Transverse Momentum Broadening via Forward Dijet Correlations

    Jiangyong Jia🇺🇸 · Shu-Yi Wei🇫🇷 · Bo-Wen Xiao🇨🇳 · Feng Yuan🇺🇸

    Dijet azimuthal angle correlation is arguably one of the most direct probes of the medium-induced broadening effects. The evidence for such broadening, however, is not yet clearly observed within the precision of current mid-rapidity measurements at RHIC and the LHC. We show that the dijet correlation in forward rapidity from the future LHC RUN3, aided by forward detector upgrades, can reveal this broadening thanks to the steeper jet spectra, suppressed vacuum radiations and lower underlying event background, with a sensitivity comparable to that of the future high-luminosity Au+Au run at RHIC. Dijet correlation measurements at the two facilities together can provide powerful constraints on the temperature dependence of medium transport properties.

    hep-phhep-exPRD(2020)·12 citations
14. 14*

    Double Heavy baryons and Corrections to Heavy Quark-Diquark Symmetry Prediction for Hyperfine Splitting

    Thomas Mehen🇺🇸 · Abhishek Mohapatra🇺🇸

    In the $m_Q\to \infty$ limit, the hyperfine splittings in the ground state doubly heavy baryons $\left(QQq\right)$ and single heavy antimesons $(\bar{Q}q)$ are related by heavy quark-diquark symmetry (HQDQ) as the light degrees of freedom in both the hadrons are expected to have identical configurations. In this article, working within the framework of nonrelativistic QCD (NRQCD), we study the perturbative and nonperturbative corrections to the HQDQ symmetry hyperfine splitting relation that scale as $\mathcal{O}\left({\alpha }_s^2\right)$ and ${\Lambda }_{\mathrm{QCD}}^2/m_Q^2$ respectively. In the extreme heavy quark limit, the perturbative corrections to hyperfine splitting of doubly charm or bottom baryons are a few percent or smaller. The nonperturbative corrections to hyperfine splitting are of order $10\%$ in the case of doubly charm baryons and $1\%$ or smaller in doubly bottom baryons.

    hep-ph0 citations
15. 15*

    Polarization modes of gravitational waves in Quadratic Gravity

    Pratik Wagle🇺🇸 · Alexander Saffer🇺🇸 · Nicolas Yunes🇺🇸

    The observation of the inspiral and merger of compact binaries by the LIGO-Virgo collaboration has allowed for new tests of Einstein's theory in the extreme gravity regime, where gravitational interactions are simultaneously strong, non-linear, and dynamical. Theories beyond Einstein's can also be constrained by detecting the polarization modes of gravitational waves. In this paper, we show that dynamical Chern-Simons and Einstein-dilaton-Gauss-Bonnet gravity cannot be differentiated from general relativity based on the detection of polarization modes alone. To prove this result, we use the Newman-Penrose method and an irreducible decomposition method to find that only the tensorial modes can be detected in both these theories.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2019)·49 citations
16. 16*

    Transplanckian Censorship and the Local Swampland Distance Conjecture

    Patrick Draper🇺🇸 · Szilard Farkas🇺🇸

    The swampland distance conjecture (SDC) addresses the ability of effective field theory to describe distant points in moduli space. It is natural to ask whether there is a local version of the SDC: is it possible to construct local excitations in an EFT that sample extreme regions of moduli space? In many cases such excitations exhibit horizons or instabilities, suggesting that there are bounds on the size and structure of field excitations that can be achieved in EFT. Static bubbles in ordinary Kaluza-Klein theory provide a simple class of examples: the KK radius goes to zero on a smooth surface, locally probing an infinite distance point, and the bubbles are classically unstable against radial perturbations. However, it is also possible to stabilize KK bubbles at the classical level by adding flux. We study the impact of imposing the Weak Gravity Conjecture (WGC) on these solutions, finding that a rapid pair production instability arises in the presence of charged matter with $q/m\gtrsim 1$. We also analyze 4d electrically charged dilatonic black holes. Small curvature at the horizon imposes a bound $\log (M_{BH})\gtrsim |\Delta \varphi |$, independent of the WGC, and the bound can be strengthened if the particle satisfying the WGC is sufficiently light. We conjecture that quantum gravity in asymptotically flat space requires a general bound on large localized moduli space excursions of the form $|\Delta \varphi |\lesssim |\log (R\Lambda )|$, where $R$ is the size of the minimal region enclosing the excitation and ${\Lambda }^{-1}$ is the short-distance cutoff on local EFT. The bound is qualitatively saturated by the dilatonic black holes and Kaluza-Klein monopoles.

    ↳ hep-thgr-qchep-phJHEP(2020)·33 citations
17. 17*

    Bottomonium resonances with $I=0$ from lattice QCD correlation functions with static and light quarks

    Pedro Bicudo🇵🇹 · Marco Cardoso🇵🇹 · Nuno Cardoso🇵🇹 · Marc Wagner🇩🇪

    We discuss, how to study $I=0$ quarkonium resonances decaying into pairs of heavy-light mesons using static potentials from lattice QCD. These static potentials can be obtained from a set of correlation functions containing both static and light quarks. As a proof of concept we focus on bottomonium with relative orbital angular momentum $L=0$ of the $\bar{b}b$ pair corresponding to $J^{PC}=0^{-+}$ and $J^{PC}=1^{--}$. We use static potentials from an existing lattice QCD string breaking study and compute phase shifts and $\text{mbox}T$ matrix poles for the lightest heavy-light meson-meson decay channel. We discuss our results in the context of corresponding experimental results, in particular for ${\rm Y}(10860)$ and ${\rm Y}(11020)$.

    ↳ hep-lathep-phPRD(2020)·46 citations
18. 18*

    Unified early and late Universe cosmology through dissipative effects in steep quintessential inflation potential models

    Gustavo B. F. Lima🇧🇷 · Rudnei O. Ramos🇧🇷

    By making use of a class of steep exponential type of potentials, which has been recently used to describe quintessential inflation, we show how a unified picture for both inflation, dark energy and dark matter can emerge entirely through dissipative effects. Dissipation provides a way for extending the applicability of a larger class of these potentials in the sense of leading to a consistent early Universe inflationary picture and producing observables in agreement with the Planck legacy data. Likewise, dissipative effects lead to dark matter production with consistent abundances and, towards the recent time of the Universe, drives the potential energy of the scalar quintessential field to dominate again, essentially mimicking a cosmological constant by today, with all cosmological parameters consistent with the observations. Both early and late Universes are connected and with no kination period in between.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2019)·44 citations
19. 19*

    Formation of Primordial Black Holes from Warm Inflation

    Richa Arya🇮🇳

    Primordial Black Holes (PBHs) serve as a unique probe to the physics of the early Universe, particularly inflation. In light of this, we study the formation of PBHs by the collapse of overdense perturbations generated during a model of warm inflation. For our model, we find that the primordial curvature power spectrum is red-tilted (spectral index $n_s<1$) at the large scale (small $k$) and is consistent with the $n_s-r$ values allowed from the CMB observations. Along with that, it has a blue-tilt ($n_s>1$) for the small PBH scales (large $k$), with a sufficiently large amplitude of the primordial curvature power spectrum required to form PBHs. These features originate because of the inflaton's coupling with the other fields during warm inflation. We discuss the role of the inflaton dissipation to the enhancement in the primordial power spectrum at the PBH scales. We find that for some parameter range of our warm inflation model, PBHs with mass $\sim 10^3$ g can be formed with significant abundance. Such tiny mass PBHs have a short lifetime $\sim 10^{-19}$ s and would have evaporated into Hawking radiation in the early Universe. Further in this study, we discuss the evaporation constraints on the initial mass fraction of the generated PBHs and the possibility of Planck mass PBH relics to constitute the dark matter.

    ↳ astro-ph.COhep-phJCAP(2020)·58 citations
20. 20*

    Keeping an Eye on DBI: Power-counting for small-$c_s$ Cosmology

    Ivana Babic🇨🇦 · C.P. Burgess🇨🇦 · Ghazal Geshnizjani🇨🇦

    Inflationary mechanisms for generating primordial fluctuations ultimately compute them as the leading contributions in a derivative expansion, with corrections controlled by powers of derivatives like the Hubble scale over Planck mass: $H/M_p$. At face value this derivative expansion breaks down for models with a small sound speed, $c_s$, to the extent that $c_s\ll 1$ is obtained by having higher-derivative interactions like ${\mathfrak{L}}_{\mathrm{eff}}\sim (\partial \Phi {)}^4$ compete with lower-derivative propagation. This concern arises more generally for models whose lagrangian is given as a function $P(X)$ for $X=-{\partial }_{\mu }\Phi {\partial }^{\mu }\Phi$ --- including in particular DBI models for which $P(X)\propto \sqrt{1-kX}$ --- since these keep all orders in $\partial \Phi$ while dropping ${\partial }^n\Phi$ for $n>1$. We here find a sensible power-counting scheme for DBI models that gives a controlled expansion in powers of three types of small parameters: $H/M_p$, slow-roll parameters (possibly) and $c_s\ll 1$. We do not find a similar expansion framework for generic small-$c_s$ or $P(X)$ models. Our power-counting result quantifies the theoretical error for any prediction (such as for inflationary correlation functions) by fixing the leading power of these small parameters that is dropped when not computing all graphs (such as by restricting to the classical approximation); a prerequisite for meaningful comparisons with observations. The new power-counting regime arises because small $c_s$ alters the kinematics of free fluctuations in a way that changes how interactions scale at low energies, in particular allowing $1-c_s$ to be larger than derivative-measuring quantities like $(H/M_p{)}^2$.

    ↳ gr-qchep-phhep-thJCAP(2020)·14 citations
21. 21*

    Identifying hadronic charmonium decays in hadron colliders

    Nicolo de Groot🇳🇱 · Sergi Castells🇺🇸

    Identification of charmonium states at hadron colliders has mostly been limited to leptonic decays of the J/{\psi}. In this paper we present and algorithm to identify hadronic decays of charmonium states (J/{\psi}, {\psi}(2S), \chi_{c0,1,2}) which make up the large majority of all decays. The algorithm is able to identify hadronic $J/\psi$ decays with an efficiency of 36\% while suppressing a background of quark and gluon jets by a factor 100.

    ↳ hep-exhep-phSciPost Phys.Core(2020)·1 citation
22. 22*

    Do electromagnetic effects survive in the production of lepton pairs in nucleus-nucleus collisions ?

    Antoni Szczurek🇵🇱

    We discuss production of $J/\psi$ and $e^{+}{e}^{-}$ pairs in semicentral and peripheral collisions of heavy ions at high energies. We focus on photoproduction mechanism. We present explanation of results of the ALICE collaboration for low transverse momentum production of $J/\psi$ as well as results obtained by the STAR collaboration for $e^{+}{e}^{-}$ production, also at low transverse momenta. We conclude that such effects are important also in this new corner (semi-central processes) of the phase space.

    ↳ nucl-thhep-phPoS(2020)·0 citations

* 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.