Mon·Oct 15, 2018Monday·October 15, 2018

1. 01*

   Elastic light-by-light scattering in a nonminimal Lorentz violation scenario

   Y.M.P. Gomes🇧🇷 · J. T. Guaitolini Junior🇧🇷

   In the last years the Lorentz Violation scheme was implemented in QFT, in special in standard model of particle physics, in an attempt to explain our actual open problems. In this work we analyze nonminimal couplings between a Lorentz-violating 4-vector and the photon field and the leptonic current of QED. The 1-loop contribution of the elastic photon-photon scattering is showed and the novel characteristics which arose are pointed out.

   hep-phhep-thPRD(2019)·13 citations
2. 02*

   Confronting the fourth generation two Higgs doublet model with the phenomenology of heavy Higgs bosons

   Sin Kyu Kang🇰🇷 · Zhuoni Qian🇰🇷 · Jeonghyeon Song🇰🇷 · Yeo Woong Yoon🇰🇷

   A sequential fourth generation is known to be excluded because the non-decoupling contribution to ${\kappa }_g$, the Higgs coupling modifier with a gluon pair, is unacceptably large. Recently a new way to save the model was suggested in the Type-II two Higgs doublet model: if the Yukawa couplings of down-type fermions have wrong-sign, the contributions from $t^{\prime }$ and $b^{\prime }$ to ${\kappa }_g$ are cancelled. We study the theoretical and experimental constraints on this model, focusing on the heavy Higgs bosons. Two constraining features are pointed out. First the exact wrong-sign limit does not allow the alignment, which makes the perturbative unitarity for the scalar-scalar scattering put the upper bounds on the heavy Higgs boson masses like $M_H,M_A\lesssim 920$ GeV and $M_{H^{\pm }}\lesssim 620$ GeV. Secondly, the Yukawa couplings of the fourth generation fermions to the heavy Higgs bosons are generically large as being proportional to the heavy fermion mass and, for the down-type fermions, to $\tan \beta$ as well. The gluon fusion productions of $H$ and $A$ through the fourth generation quark loops become significant. We found that the current LHC data on $pp\to ZZ$ for $H$ along with the theoretical and indirect constraints exclude the model at leading order.

   hep-phPRD(2018)·8 citations
3. 03*

   FlexibleSUSY: Precise automated calculations in any BSM theory

   Peter Athron🇦🇺 · Markus Bach🇦🇺 · Dylan Harries🇦🇺 · Wojciech Kotlarski🇩🇪 · Thomas Kwasnitza🇩🇪 · Jae-hyeon Park🇰🇷 · Tom Steudtner🇬🇧 · Dominik Stöckinger🇩🇪 · Alexander Voigt🇩🇪 · Jobst Ziebell🇦🇺

   FlexibleSUSY is a software package for various calculations in any model of physics beyond the standard model (not just any supersymmetric model). FlexibleSUSY can solve boundary value problems and uses this to find $\overline{DR}/\overline{MS}$ parameters and calculate the Higgs and BSM particle masses, as well as other observables. FlexibleSUSY is designed to be adaptable, fast, precise and reliable. We describe FlexibleSUSY with particular emphasis on recent developments and the state of the art Higgs mass calculations it can perform. We also show some applications to illustrate how it can be used to obtain interesting physics results with the highest precision possible and with remarkable speed.

   hep-phPoS(2019)·2 citations
4. 04*

   Phenomenological implications of the Friedberg-Lee transformation in a neutrino mass model with $\mu \tau$-flavored CP symmetry

   Roopam Sinha🇮🇳 · Sukannya Bhattacharya🇮🇳 · Rome Samanta🇬🇧

   We propose a neutrino mass model with $\mu \tau$-flavored CP symmetry, where the effective light neutrino Lagrangian enjoys an additional invariance under a Friedberg-Lee (FL) transformation on the left-handed flavor neutrino fields, that leads to a highly predictive and testable scenario. While both types of the light neutrino mass ordering, i.e., Normal Ordering (NO) as well as the Inverted Ordering (IO) are allowed, the absolute scale of neutrino masses is fixed by the vanishing determinant of light Majorana neutrino mass matrix $M_{\nu }$. We show that for both types of mass ordering, whilst the atmospheric mixing angle ${\theta }_{23}$ is in general nonmaximal (${\theta }_{23}\ne \pi /4$), the Dirac CP phase $\delta$ is exactly maximal ($\delta =\pi /2,3\pi /2$) for IO and nearly maximal for NO owing to $\cos \delta \propto \sin {\theta }_{13}$. For the NO, very tiny nonvanishing Majorana CP violation might appear through one of the Majorana phases $\beta$; otherwise the model predicts vanishing Majorana CP violation. Thus, despite the fact, that from the measurement of ${\theta }_{23}$, it is difficult to rule out the model, any large deviation of $\delta$ from its maximality, will surely falsify the scenario. For a comprehensive numerical analysis, beside fitting the neutrino oscillation global fit data, we also present a study on the ${\nu }_{\mu }\to {\nu }_e$ oscillation which is expected to show up Dirac CP violation in different long baseline experiments. Finally, assuming purely astrophysical sources, we calculate the Ultra High Energy (UHE) neutrino flavor flux ratios at neutrino telescopes, such as IceCube, from which statements on the octant of ${\theta }_{23}$ could be made in our model.

   hep-phastro-ph.COJHEP(2019)·7 citations
5. 05*

   Light charged Higgs boson with dominant decay to quarks and its search at LHC and future colliders

   A.G. Akeroyd🇬🇧 · Stefano Moretti🇬🇧 · Muyuan Song🇬🇧

   The possibility of a light charged Higgs boson $H^{\pm }$ that decays predominantly to quarks ($cs$ and/or $cb$) and with a mass in the range 80 GeV $\le m_{H^{\pm }}\le 90$ GeV is studied in the context of Three-Higgs-Doublet Models (3HDMs). At present the Large Hadron Collider (LHC) has little sensitivity to this scenario, and currently the best constraints are from LEP2 and Tevatron searches. The branching ratio of $H^{\pm }\to cb$ can be dominant in two of the five types of 3HDM, and we determine the parameter space where this occurs. The decay $H^{\pm }\to cb$ has recently been searched for at the LHC for the first time, and with increased integrated luminosity one would expect sensitivity to the region 80 GeV $\le m_{H^{\pm }}\le 90$ GeV due to the smaller backgrounds with respect to $H^{\pm }\to cs$ decays.

   hep-phPRD(2018)·34 citations
6. 06*

   Precision electroweak shift of muonium hyperfine splitting

   T. Asaka🇯🇵 · M. Tanaka🇯🇵 · K. Tsumura🇯🇵 · M.Yoshimura🇯🇵

   Electroweak second order shifts of muonium (${\mu }^{+}{e}^{-}$ bound state) energy levels are calculated for the first time. Calculation starts from on-shell one-loop elastic ${\mu }^{+}{e}^{-}$ scattering amplitudes in the center of mass frame, proceed to renormalization and to derivation of muonium matrix elements by using the momentum space wave functions. This is a reliable method unlike the unjustified four-Fermi approximation in the literature. Corrections of order $\alpha G_F$ (with $\alpha \sim 1/137$ the fine structure constant and $G_F$ the Fermi constant) and of order $\alpha G_F/(m_Z{a}_B)$ (with $m_Z$ the Z boson mass and $a_B$ the Bohr radius) are derived from three classes of Feynman diagrams, Z self-energy, vertex and box diagrams. The ground state muonium hyperfine splitting is given in terms of the only experimentally unknown parameter, the smallest neutrino mass. It is however found that the neutrino mass dependence is very weak, making its detection difficult.

   hep-phhep-ex14 citations
7. 07*

   Combining texture zeros with a remnant CP symmetry in the minimal type-I seesaw

   D. M. Barreiros🇵🇹 · R. G. Felipe🇵🇹 · F. R. Joaquim🇵🇹

   In the framework of the two right-handed neutrino seesaw model, we consider maximally-restrictive texture-zero patterns for the lepton Yukawa coupling and mass matrices, together with the existence of a remnant CP symmetry. Under these premisses, we find that several textures are compatible with the most recent data coming from neutrino oscillation and neutrinoless double beta decay experiments. It is shown that the number of allowed texture zeros depends on the type of heavy right-handed neutrino mass spectrum. Namely, at most one (two)-zero patterns are allowed in the Dirac Yukawa coupling matrix for nondegenerate (degenerate) heavy Majorana neutrinos. The predictions for the low-energy Dirac and Majorana CP-violating phases, and for the effective mass parameter relevant in neutrinoless double-beta decay experiments, are presented and discussed. We also comment on the impact of future experimental improvements in scrutinising texture-zero patterns with a remnant CP symmetry, within the minimal version of the seesaw mechanism considered here.

   hep-phJHEP(2019)·44 citations
8. 08*

   Absorptive effects and power corrections in low $x$ DGLAP evolution

   M.R. Pelicer🇧🇷 · E.G. de Oliveira🇧🇷 · A.D. Martin🇬🇧 · M.G. Ryskin🇬🇧

   We address a long standing problem concerning the scale behaviour of parton densities in the low $x$, low $Q^2$ domain. We emphasize the important role of absorptive corrections at low $x$ and use knowledge of diffractive deep inelastic scattering to exclude the absorptive effect from conventional deep inelastic data. In this way we obtain a significantly different low $x$ behaviour of the gluon density, which is now much better described by linear DGLAP evolution. Accounting also for a second power correction, which arises from the freezing of ${\alpha }_s$ at low $Q^2$, leads to an essentially flat behaviour of the low $x$ gluon density.

   hep-phEPJC(2019)·21 citations
9. 09*

   Opening the energy window on direct dark matter detection

   Nassim Bozorgnia🇬🇧 · David G. Cerdeno🇬🇧 · Andrew Cheek🇬🇧 · Bjoern Penning🇺🇸

   In this article we investigate the benefits of increasing the maximum nuclear recoil energy analysed in dark matter (DM) direct detection experiments. We focus on elastic DM-nucleus interactions, and work within the framework of effective field theory (EFT) to describe the scattering cross section. In agreement with previous literature, we show that an increased maximum energy leads to more stringent upper bounds on the DM-nucleus cross section for the EFT operators, especially those with an explicit momentum dependence. In this article we extend the energy region of interest (ROI) to show that the optimal values of the maximum energy for xenon and argon are of the order of 500 keV and 300 keV, respectively. We then show how, if a signal compatible with DM is observed, an enlarged energy ROI leads to a better measurement of the DM mass and couplings. In particular, for a xenon detector, DM masses of the order of 200 GeV (2 TeV) or lower can be reconstructed for momentum-independent (-dependent) operators. We also investigate three-dimensional parameter reconstruction and apply it to the specific case of scalar DM and anapole DM. We find that opening the energy ROI is an excellent way to identify the linear combination of momentum-dependent and momentum-independent operators, and it is crucial to correctly distinguish these models. Finally, we show how an enlarged energy ROI also allows us to test astrophysical parameters of the DM halo, such as the DM escape speed.

   hep-phastro-ph.COJCAP(2018)·24 citations
10. 10*

    Probing Multicomponent Extension of Inert Doublet Model with a Vector Dark Matter

    Sreemanti Chakraborti🇮🇳 · Amit Dutta Banik🇮🇳 · Rashidul Islam🇮🇳

    Although theoretically well-motivated as a minimal consistent Dark Matter (DM) model, the Inert Doublet Model (IDM) fell short in explaining the existence of DM in the intermediate mass region ($100-500$ GeV). We try to address this problem by introducing an additional vector dark matter. We show that the relic density of inert dark matter candidate can be enhanced significantly with new interactions in the intermediate mass region $100-500$ GeV in the multicomponent dark matter model when compared with the usual single component inert doublet model. We also show that we can get a reasonable excess in the $/E_T$ distribution if we do not apply a very hard $/E_T$ cut on it as is customary in any dark matter search at the LHC.

    hep-phEPJC(2019)·33 citations
11. 11*

    Neutrino Charge Radii from COHERENT Elastic Neutrino-Nucleus Scattering

    M. Cadeddu🇮🇹 · C. Giunti🇮🇹 · K.A. Kouzakov🇷🇺 · Y.F. Li🇨🇳 · A.I. Studenikin🇷🇺 · Y.Y. Zhang🇨🇳

    Coherent elastic neutrino-nucleus scattering is a powerful probe of neutrino properties, in particular of the neutrino charge radii. We present the bounds on the neutrino charge radii obtained from the analysis of the data of the COHERENT experiment. We show that the time information of the COHERENT data allows us to restrict the allowed ranges of the neutrino charge radii. We also obtained for the first time bounds on the neutrino transition charge radii, which are quantities beyond the Standard Model.

    hep-phPRD(2018)·138 citations
12. 12*

    Extended Gauge Mediation in the NMSSM with Displaced LHC Signals

    Marcin Badziak🇵🇱 · Nishita Desai🇫🇷 · Cyril Hugonie🇫🇷 · Robert Ziegler🇨🇭

    We analyze models of extended Gauge Mediation in the context of the NMSSM, concentrating on supersymmetric spectra with light gluinos, low fine-tuning and decays of the lightest neutralino leading to displaced vertices. While the minimal scenario has rather heavy gluinos as a result of restrictions from the Higgs sector, we propose two new models in which the gluino can be as light as allowed by direct searches at the LHC, with a mass of about 1.7 TeV and 2.0 TeV, respectively. Both models have a tuning of a few permille, and lead to an interesting phenomenology due to a light singlet sector. A singlet state at around 98 GeV can account for the LEP excess, while the singlino has a mass of the order of 100 GeV and decays to b-jets and the gravitino, with decay lengths of a few cm.

    hep-phEPJC(2019)·3 citations
13. 13*

    Constraining $A_4$ Leptonic Flavour Model Parameters at Colliders and Beyond

    Lukas Heinrich🇺🇸 · Holger Schulz🇺🇸 · Jessica Turner🇺🇸 · Ye-Ling Zhou🇬🇧

    The observed pattern of mixing in the neutrino sector may be explained by the presence of a non-Abelian, discrete flavour symmetry broken into residual subgroups at low energies. Many flavour models require the presence of Standard Model singlet scalars which can promptly decay to charged leptons in a flavour-violating manner. We constrain the model parameters of a generic $A_4$ leptonic flavour model using a synergy of experimental data including limits from charged lepton flavour conversion, an 8 TeV collider analysis and constraints from the anomalous magnetic moment of the muon. The most powerful constraints derive from the MEG collaborations' limit on Br$\left(\mu \to e\gamma \right)$ and the reinterpretation of an 8 TeV ATLAS search for anomalous productions of multi-leptonic final states. We quantify the exclusionary power of each of these experiments and identify regions where the constraints from collider and MEG experimental data are complementary.

    hep-phJHEP(2019)·13 citations
14. 14*

    Investigating the Topology Dependence of Quark and Gluon Jets

    Samuel Bright-Thonney🇺🇸 · Benjamin Nachman🇺🇸

    As most target final states for searches and measurements at the Large Hadron Collider have a particular quark/gluon composition, tools for distinguishing quark- from gluon-initiated jets can be very powerful. In addition to the difficulty of the classification task, quark-versus-gluon jet tagging is challenging to calibrate. The difficulty arises from the topology dependence of quark-versus-gluon jet tagging: since quarks and gluons have net quantum chromodynamic color charge while only colorless hadrons are measured, the radiation pattern inside a jet of a particular type depends on the rest of its environment. Given a definition of a quark or gluon jet, this paper studies the topology dependence of such jets in simulation. A set of phase space regions and jet substructure observables are identified for further comparative studies between generators and eventually in data.

    hep-phhep-exJHEP(2019)·35 citations
15. 15*

    Decays of the f0(1370) scalar glueball candidate in pp Central Exclusive Production (CEP) and in antiproton annihilations at rest

    Ugo Gastaldi🇮🇹

    Decays into two charged pions of the f0(1370) are the main source of an isolated structure localized between 1.2 and 1.5 GeV in the two charged pions mass spectrum measured in pp Central Exclusive Production (CEP) at 200 GeV at very low four momentum transfer ltl by the STAR experiment. These data confirm in the two charged pions decay channel the existence of the f0(1370) as an isolated well identified structure previously observed in K+K-, KsKs, 4 charged pions, two charged and two neutral pions and 4 neutral pions decays measured in antiproton annihilations at rest. The ensemble of these data point at a high gluon content of the f0(1370). CEP interactions at higher energies favour production of 0++ and 2++ mesons. Selection of events with lower ltl at both proton vertices suppresses 2++ structures. LHC runs dedicated to pp CEP measurements at low ltl could then provide a unique source of all the low energy scalars. This would make it clear if and where scalar gluonium is resident and the nature (composition in terms of quarks, antiquarks and gluons) of f0(500), f0(980), f0(1370), f0(1500) and f0(1710).

    hep-phEPJ Web Conf.(2018)·0 citations
16. 16*

    Inflation as an Information Bottleneck - A strategy for identifying universality classes and making robust predictions

    Mafalda Dias🇩🇪 · Jonathan Frazer🇩🇪 · Alexander Westphal🇩🇪

    In this work we propose a statistical approach to handling sources of theoretical uncertainty in string theory models of inflation. By viewing a model of inflation as a probabilistic graph, we show that there is an inevitable information bottleneck between the ultraviolet input of the theory and observables, as a simple consequence of the data processing theorem. This information bottleneck can result in strong hierarchies in the sensitivity of observables to the parameters of the underlying model and hence universal predictions with respect to at least some microphysical considerations. We also find other intriguing behaviour, such as sharp transitions in the predictions when certain hyperparameters cross a critical value. We develop a robust numerical approach to studying these behaviours by adapting methods often seen in the context of machine learning. We first test our approach by applying it to well known examples of universality, sharp transitions, and concentration phenomena in random matrix theory. We then apply the method to inflation with axion monodromy. We find universality with respect to a number of model parameters and that consistency with observational constraints implies that with very high probability certain perturbative corrections are non-negligible.

    ↳ hep-thastro-ph.COhep-phJHEP(2019)·11 citations
17. 17*

    Ernest Henley's Isospin and the Ensuing Progress

    Gerald A. Miller🇺🇸

    Ernest Henley's contributions to understanding isospin symmetry and the experimental and theoretical progress that followed are reviewed. Many experimentalists and theorists worked to bring Ernest's early vision of the subject to fruition. This progress and wide-ranging impact is described.

    ↳ nucl-thhep-phnucl-exIJMPE(2018)·0 citations
18. 18*

    Constraints on symmetry from holography

    Daniel Harlow🇺🇸 · Hirosi Ooguri🇺🇸

    In this letter we use the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence to establish a set of old conjectures about symmetries in quantum gravity. These are that no global symmetries are possible, that internal gauge symmetries must come with dynamical objects that transform in all irreducible representations, and that internal gauge groups must be compact. These conjectures are not obviously true from a bulk perspective, they are nontrivial consequences of the non-perturbative consistency of the correspondence. More details of and background for these arguments are presented in an accompanying paper.

    ↳ hep-thgr-qchep-phPRL(2019)·263 citations
19. 19*

    Symmetries in quantum field theory and quantum gravity

    Daniel Harlow🇺🇸 · Hirosi Ooguri🇺🇸

    In this paper we use the AdS/CFT correspondence to refine and then establish a set of old conjectures about symmetries in quantum gravity. We first show that any global symmetry, discrete or continuous, in a bulk quantum gravity theory with a CFT dual would lead to an inconsistency in that CFT, and thus that there are no bulk global symmetries in AdS/CFT. We then argue that any "long-range" bulk gauge symmetry leads to a global symmetry in the boundary CFT, whose consistency requires the existence of bulk dynamical objects which transform in all finite-dimensional irreducible representations of the bulk gauge group. We mostly assume that all internal symmetry groups are compact, but we also give a general condition on CFTs, which we expect to be true quite broadly, which implies this. We extend all of these results to the case of higher-form symmetries. Finally we extend a recently proposed new motivation for the weak gravity conjecture to more general gauge groups, reproducing the "convex hull condition" of Cheung and Remmen. An essential point, which we dwell on at length, is precisely defining what we mean by gauge and global symmetries in the bulk and boundary. Quantum field theory results we meet while assembling the necessary tools include continuous global symmetries without Noether currents, new perspectives on spontaneous symmetry-breaking and 't Hooft anomalies, a new order parameter for confinement which works in the presence of fundamental quarks, a Hamiltonian lattice formulation of gauge theories with arbitrary discrete gauge groups, an extension of the Coleman-Mandula theorem to discrete symmetries, and an improved explanation of the decay ${\pi }^0\to \gamma \gamma$ in the standard model of particle physics. We also describe new black hole solutions of the Einstein equation in $d+1$ dimensions with horizon topology ${\mathbb{T}}^p\times {\mathbb{S}}^{d-p-1}$.

    ↳ hep-thgr-qchep-lathep-phCommun.Math.Phys.(2021)·596 citations
20. 20*

    Constraining D-foam via the 21-cm Line

    John Ellis🇬🇧 · Nick E. Mavromatos🇬🇧 · Dimitri V. Nanopoulos🇺🇸

    We have suggested earlier that D-particles, which are stringy space-time defects predicted in brane-inspired models of the Universe, might constitute a component of dark matter, and that they might contribute to the masses of singlet fermions that could provide another component. Interactions of the quantum-fluctuating D-particles with matter induce vector forces that are mediated by a massless effective U(1) gauge field, the "D-photon", which is distinct from the ordinary photon and has different properties from dark photons. We discuss the form of interactions of D-matter with conventional matter induced by D-photon exchange and calculate their strength, which depends on the density of D-particles. Observations of the hydrogen 21~cm line at redshifts >= 15 can constrain these interactions and the density of D-matter in the early Universe.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2019)·0 citations
21. 21*

    Solving the PCAC puzzle for nucleon axial and pseudoscalar form factors

    G. S. Bali🇩🇪 · S. Collins🇩🇪 · M. Gruber🇩🇪 · A. Schäfer🇩🇪 · P. Wein🇩🇪 · T. Wurm🇩🇪

    It has been observed in multiple lattice determinations of isovector axial and pseudoscalar nucleon form factors, that, despite the fact that the partial conservation of the axialvector current is fulfilled on the level of correlation functions, the corresponding relation for form factors (sometimes called the generalized Goldberger-Treiman relation in the literature) is broken rather badly. In this work we trace this difference back to excited state contributions and propose a new projection method that resolves this problem. We demonstrate the efficacy of this method by computing the axial and pseudoscalar form factors as well as related quantities on ensembles with two flavors of improved Wilson fermions using pion masses down to 150 MeV. To this end, we perform the $z$-expansion with analytically enforced asymptotic behaviour and extrapolate to the physical point.

    ↳ hep-lathep-phPLB(2019)·64 citations
22. 22*

    Towards a proof of the Weak Gravity Conjecture

    Alfredo Urbano🇮🇹

    The Weak Gravity Conjecture (WGC) asserts a powerful consistency condition on gauge theories coupled to gravity, and it is widely believed that its proof will shed light on the quantum origin of gravitational interactions. Holography, and in particular the AdS/CFT correspondence, is a well-suited tool by means of which it is possible to explore the world of gravity. From the holographic perspective, gravity is an emergent statistical phenomenon, and the laws of gravitation can be recast as the laws of thermodynamics. It is interesting to ask whether the WGC can be formulated in terms of the AdS/CFT correspondence. A positive answer is given: The WGC in the bulk is linked to the thermalization properties of the CFT living on the boundary. The latter is related to the Sachdev-Ye-Kitaev model of strange metals. In the thermodynamic picture, the validity of the WGC is verified.

    ↳ hep-thhep-ph35 citations
23. 23*

    Rescuing Massive Photons from the Swampland

    Nathaniel Craig🇺🇸 · Isabel Garcia Garcia🇺🇸

    Stringent Swampland conjectures aimed at effective theories containing massive abelian vectors have recently been proposed (arXiv:1808.09966), with striking phenomenological implications. In this article, we show how effective theories that parametrically violate the proposed conjectures can be UV-completed into theories that satisfy them. The UV-completion is accessible through both the Stückelberg and Higgs mechanisms, with all dimensionless parameters taking $\mathcal{O}(1)$ values from the UV perspective. These constructions feature an IR limit containing a light vector that is parametrically separated from any other massive states, and from any cut-off scale mandated by quantum gravity consistency requirements. Moreover, the cut-off--to--vector--mass ratio remains parametrically large even in the decoupling limit in which all other massive states (including any scalar excitations) become arbitrarily heavy. We discuss how apparently strong constraints imposed by the proposed conjectures on phenomenologically interesting models, including specific production mechanisms of dark photon dark matter, are thereby circumvented.

    ↳ hep-thhep-phJHEP(2018)·30 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.