Fri·Jul 6, 2018Friday·July 6, 2018

1. 01*

   Dark Matter, Millicharges, Axion and Scalar Particles, Gauge Bosons, and Other New Physics with LDMX

   Asher Berlin🇺🇸 · Nikita Blinov🇺🇸 · Gordan Krnjaic🇺🇸 · Philip Schuster🇺🇸 · Natalia Toro🇺🇸

   The proposed LDMX experiment would provide roughly a meter-long region of instrumented tracking and calorimetry that acts as a beam stop for multi-GeV electrons in which each electron is tagged and its evolution measured. This would offer an unprecedented opportunity to access both collider-invisible and ultra-short lifetime decays of new particles produced in electron (or muon)-nuclear fixed-target collisions. In this paper, we show that the missing momentum channel and displaced decay signals in such an experiment could provide world-leading sensitivity to sub-GeV dark matter, millicharged particles, and visibly or invisibly decaying axions, scalars, dark photons, and a range of other new physics scenarios.

   hep-phastro-ph.COhep-exPRD(2019)·303 citations
2. 02*

   Probing Electroweak Precision Physics via boosted Higgs-strahlung at the LHC

   Shankha Banerjee🇬🇧 · Christoph Englert🇬🇧 · Rick S. Gupta🇬🇧 · Michael Spannowsky🇬🇧

   We study the process $pp\to Z({\ell }^{+}{\ell }^{-})h(b\bar{b})$ in the Standard Model Effective Field Theory (SMEFT) at high energies using subjet techniques to reconstruct the Higgs boson. We show that at high energies this process probes four directions in the dimension 6 EFT space, namely the operators that contribute to the four contact interactions, $h{Z}_{\mu }\bar{f}{\gamma }^{\mu }f$, where $f=u_L,u_R,d_L$ and $d_R$. These four directions are, however, already constrained by the $Z$-pole and diboson measurements at LEP. We show that by utilising the energy growth of this process in the SMEFT and the accuracy that can be achieved by using subjet techniques at the High Luminosity LHC, one can obtain bounds on these operators that are an order of magnitude better than existing LEP bounds.

   hep-phhep-exPRD(2018)·76 citations
3. 03*

   First radial excitations of heavy quarkonium in a contact interaction

   Marco Antonio Bedolla🇲🇽 · Elena Santopinto🇮🇹

   For the flavor-singlet heavy quark systems of quarkonia, we compute the masses of the first radial excitation of mesons in four different channels: pseudo-scalar (${\eta }_{c,b}(2S)$), vector ($\psi (2S),{\rm Y}(2S)$), scalar (${\chi }_{c_0,b_0}(2P)$) and axial vector (${\chi }_{c_1,b_1}(2P)$), as well as the weak decay constants of the ${\eta }_{c,b}(2S)$ and $\psi (2S),{\rm Y}(2S)$. The framework for this analysis is provided by a symmetry-preserving Schwinger-Dyson equations treatment of a vector$\times$vector contact interaction. The results found for the meson masses are in good agreement experimental data and earlier model calculations based upon Schwinger-Dyson and Bethe-Salpeter equations (BSEs) involving sophisticated interaction kernels.

   hep-ph2 citations
4. 04*

   One-loop effects of MSSM particles in e^-e^+ \to Zh and e^-e^+ \to \nu\bar\nu h at the ILC

   Yusaku Kouda🇯🇵 · Tadashi Kon🇯🇵 · Yoshimasa Kurihara🇯🇵 · Tadashi Ishikawa🇯🇵 · Masato Jimbo🇯🇵 · Kiyoshi Kato🇯🇵 · Masaaki Kuroda🇯🇵

   The 1-loop effects of the MSSM at the ILC are investigated through numerical analysis. We studied the higgs production processes $e^{-}{e}^{+}\to Zh$ and $e^{-}{e}^{+}\to \nu \bar{\nu }h$ at the ILC. It is found that the magnitude of the MSSM contribution through the 1-loop effects is sizable enough to be detected. In the study, three sets of the MSSM parameters are proposed, which are consistent with the observed higgs mass, the muon $g$-$2$, the dark matter abundance and the decay branching ratios of $B$ mesons. In the $e^{-}{e}^{+}\to Zh$ process, the 1-loop effects of the MSSM are visible and the distinction of the parameter sets is partially possible. For the study of $e^{-}{e}^{+}\to \nu \bar{\nu }h$, we used the equivalent $W$-boson approximation in the evaluation of the 1-loop cross section. While the 1-loop effect of the MSSM is visible, the distinction of the parameter sets might not be possible in this process under the value of realistic luminosity at the ILC.

   hep-phPTEP(2018)·1 citation
5. 05*

   Revisiting $B\to \pi \pi \ell \nu$ at Large Dipion Masses

   Thorsten Feldmann🇩🇪 · Danny van Dyk🇩🇪 · K. Keri Vos🇩🇪

   We revisit QCD factorization of $B\to \pi \pi$ form factors at large dipion masses, by deriving new constraints based on the analyticity properties of these objects. We then propose a parametrization of the form factors, inspired by the leading-twist QCD factorization formula, that incorporates all known analytic properties. This parameterization is used to interpolate between the QCDF results and the constraints from the $B^{\ast }$ pole. Based on this interpolation, we predict the $B\to \pi \pi \ell \nu$ decay rate in a larger phase space region than previous studies could. We obtain a partially-integrated branching ratio up to $\mathcal{B}\simeq \mathcal{O}(10^{-6})$, which implies that a measurement of the non-resonant semileptonic decay is potentially within reach of the Belle II experiment.

   hep-phJHEP(2018)·18 citations
6. 06*

   Spin Correlations in Parton Shower Simulations

   Peter Richardson🇨🇭 · Stephen Webster🇬🇧

   Spin correlations are an important, but often neglected, effect in modern Monte Carlo event generators. We show that they can be fully incorporated in Herwig 7 using the algorithm originally proposed by Collins and Knowles in all stages of the event generation process and between the different stages of the event generation. In this paper we present the final missing ingredient, correlations in both the angular-ordered and dipole shower algorithms and between the parton shower and hard production and decay processes.

   hep-phhep-exEPJC(2020)·53 citations
7. 07*

   Effect of resonance for $CP$ asymmetry of the decay process ${\bar{B}}_s\to P{\pi }^{+}{\pi }^{-}$ in perturbative QCD

   Gang Lü🇨🇳 · Yu-Ting Wang🇨🇳 · Qin-Qin Zhi🇨🇳

   In the framework of Perturbative QCD (PQCD) approach we study the direct $CP$ asymmetry for the decay channel ${\bar{B}}_s\to P{\pi }^{+}{\pi }^{-}$ around the resonance range via the $\rho -\omega$ mixing mechanism (where P refer to pseudoscalar meson). We find that the $CP$ asymmetry can be enhanced by $\rho -\omega$ mixing when the masses of the ${\pi }^{+}{\pi }^{-}$ pairs are at the area of $\rho -\omega$ resonance, and the maximum $CP$ asymmetry can reach 59{\%} for the relevant decay channels.

   hep-phPRD(2018)·10 citations
8. 08*

   Hollowness effect and entropy in high energy elastic scattering

   S. D. Campos (Universidade Federal de São Carlos Sorocaba)🇧🇷 · V. A. Okorokov (National Research Nuclear University MEPhI)🇷🇺

   This paper presents a qualitative explanation for the hollowness effect based on the inelastic overlap function, claiming this result is a consequence of fundamental thermodynamic processes. Using the Tsallis entropy, one identifies the entropic index $w$ with the ratio of the collision energy to critical one in the total cross-section. The integrated probability density function is replaced by the inelastic overlap function, which represents the probability of occurrence of an inelastic event depending on both the collision energy and impact parameter. The Coulomb potential, as well as the confinement potential, are used as naive approaches to describe the (internal) energy of the colliding hadrons. The Coulomb potential in the impact parameter picture is not able to furnish any reliable physical result near the forward direction. However, the confinement potential in the impact parameter space results in the hollowness effect shown by the inelastic overlap function near the forward direction.

   hep-phPhys.Scripta(2020)·6 citations
9. 09*

   Importance of Loop Effects in Explaining the Accumulated Evidence for New Physics in B Decays with a Vector Leptoquark

   Andreas Crivellin🇨🇭 · Christoph Greub🇨🇭 · Dario Müller🇨🇭 · Francesco Saturnino🇨🇭

   In recent years experiments revealed intriguing hints for new physics (NP) in $B$ decays involving \bctaunu and $b\to s{\ell }^{+}{\ell }^{-}$ transitions at the $4\sigma$ and $5\sigma$ level, respectively. In addition, there are slight disagreements in $b\to u\tau \nu$ and $b\to d{\mu }^{+}{\mu }^{-}$ observables. While not significant on their own, they point in the same direction. Furthermore, $V_{us}$ extracted from $\tau$ decays shows a slight tension ($\approx 2.5\sigma$) with its value determined from CKM unitarity. Additionally, BELLE found hints for an excess in $B_d\to {\tau }^{+}{\tau }^{-}$. Concerning NP explanations, the vector leptoquark $SU(2)$ singlet is of special interest since it is the only single particle extension of the SM which can (in principle) address all the anomalies described above. For this purpose, large couplings to $\tau$ leptons are necessary and loop effects, which we calculate in this article, become important. Including them in our phenomenological analysis, we find that neither the tension in $V_{us}$ nor the excess in $B_d\to {\tau }^{+}{\tau }^{-}$ can be fully explained without violating bounds from $K\to \pi \nu \bar{\nu }$. However, one can account for $b\to c\tau \nu$ and $b\to u\tau \nu$ data finding intriguing correlations with $B_q\to {\tau }^{+}{\tau }^{-}$ and $K\to \pi \nu \bar{\nu }$. Furthermore, the explanation of $b\to c\tau \nu$ predicts a positive shift in $C_7$ and a negative one in $C_9$, being nicely in agreement with the global fit to $b\to s{\ell }^{+}{\ell }^{-}$ data. Finally, we point out that one can fully account for \bctaunu and $b\to s{\ell }^{+}{\ell }^{-}$ without violating bounds from $\tau \to \varphi \mu$, ${\rm Y}\to \tau \mu$ or $b\to s\tau \mu$ processes.

   hep-phhep-exPRL(2019)·209 citations
10. 10*

    Effect of flavor-dependent partonic transverse momentum on the determination of the $W$ boson mass in hadronic collisions

    Alessandro Bacchetta🇮🇹 · Giuseppe Bozzi🇮🇹 · Marco Radici🇮🇹 · Mathias Ritzmann🇺🇸 · Andrea Signori🇺🇸

    Within the framework of transverse-momentum-dependent factorization, we investigate for the first time the impact of a flavor-dependent intrinsic transverse momentum of quarks on the production of $W^{\pm }$ bosons in proton-proton collisions at $\sqrt{s}$ = 7 TeV. We estimate the shift in the extracted value of the $W$ boson mass $M_W$ induced by different choices of flavor-dependent parameters for the intrinsic quark transverse momentum by means of a template fit to the transverse-mass and the lepton transverse-momentum distributions of the $W$-decay products. We obtain $-6\le \Delta M_{W^{+}}\le 9$ MeV and $-4\le \Delta M_{W^{-}}\le 3$ MeV with a statistical uncertainty of $\pm 2.5$ MeV. Our findings call for more detailed investigations of flavor-dependent nonperturbative effects linked to the proton structure at hadron colliders.

    hep-phhep-exnucl-exnucl-thPLB(2019)·54 citations
11. 11*

    Global and optimal probes for the top-quark effective field theory at future lepton colliders

    Gauthier Durieux🇩🇪 · Martín Perelló🇪🇸 · Marcel Vos🇪🇸 · Cen Zhang🇨🇳

    We study the sensitivity to physics beyond the standard model of precise top-quark pair production measurements at future lepton colliders. A global effective-field-theory approach is employed, including all dimension-six operators of the Warsaw basis which involve a top-quark and give rise to tree-level amplitudes that interfere with standard-model $e^{+}{e}^{-}\to t\bar{t}\to b{W}^{+}\bar{b}{W}^{-}$ ones in the limit of vanishing $b$-quark mass. Four-fermion and CP-violating contributions are taken into account. Circular-collider-, ILC- and CLIC-like benchmark run scenarios are examined. We compare the constraining power of various observables to a set of statistically optimal ones which maximally exploit the information contained in the fully differential $b{W}^{+}\bar{b}{W}^{-}$ distribution. The enhanced sensitivity gained on the linear contributions of dimension-six operators leads to bounds that are insensitive to quadratic ones. Even with statistically optimal observables, two centre-of-mass energies are required for constraining simultaneously two- and four-fermion operators. The impact of the centre-of-mass energy lever arm is discussed, that of beam polarization as well. A realistic estimate of the precision that can be achieved in ILC- and CLIC-like operating scenarios yields individual limits on the electroweak couplings of the top quark that are one to three orders of magnitude better than constraints set with Tevatron and LHC run I data, and three to two hundred times better than the most optimistic projections made for the high-luminosity phase of the LHC. Clean global constraints can moreover be obtained at lepton colliders, robustly covering the multidimensional effective-field-theory space with minimal model dependence.

    hep-phhep-exJHEP(2018)·98 citations
12. 12*

    Double dark-matter admixed neutron star

    Zeinab Rezaei🇮🇷

    The dark matter in neutron stars can exist from the lifetime of the progenitor or captured by this compact object. The properties of dark matter entered the neutron stars through each step could be different from each other. Here, we investigate the structure of neutron stars which are influenced by the dark matter in two processes. Applying a generalization of two-fluid formalism to three-fluid one and the equation of state from the rotational curves of galaxies, we explore the structure of double dark-matter admixed neutron stars. The behavior of the neutron and dark matter portions for these stars is considered. In addition, the influence of the dark matter equations of state on the stars with different contributions of visible and dark matter is studied. The gravitational redshift of these stars in different cases of dark matter equations of state is investigated.

    ↳ astro-ph.HEastro-ph.GAgr-qchep-phInt.J.Mod.Phys.D(2018)·23 citations
13. 13*

    Evidence for a 5 MeV Spectral Deviation in the Goesgen Reactor Neutrino Oscillation Experiment

    V. Zacek🇨🇦 · G. Zacek🇨🇦 · P. Vogel🇺🇸 · J.-L. Vuilleumier🇨🇭

    Recent reactor neutrino experiments observe an anomalous excess around 5 MeV in the prompt energy spectra of positrons following the inverse beta decay reaction. In this note we suggest that this 5 MeV anomaly was already present in a much earlier experiment, which was carried out in the 1980's at three distances from the 2.8 GW nuclear powerplant at Goesgen, Switzerland. In particular we demonstrate with a log-likelihood test performed on the Goesgen data that the no-anomaly hypothesis is disfavored at a level of 3.8 sigma.

    ↳ hep-exhep-phnucl-ex13 citations
14. 14*

    Differential limit on the extremely-high-energy cosmic neutrino flux in the presence of astrophysical background from nine years of IceCube data

    IceCube Collaboration: M. G. Aartsen · M. Ackermann · J. Adams · J. A. Aguilar · M. Ahlers · M. Ahrens · I. Al Samarai · D. Altmann · K. Andeen · T. Anderson · I. Ansseau · G. Anton and 321 other authors

    We report a quasi-differential upper limit on the extremely-high-energy (EHE) neutrino flux above $5\times 10^6$ GeV based on an analysis of nine years of IceCube data. The astrophysical neutrino flux measured by IceCube extends to PeV energies, and it is a background flux when searching for an independent signal flux at higher energies, such as the cosmogenic neutrino signal. We have developed a new method to place robust limits on the EHE neutrino flux in the presence of an astrophysical background, whose spectrum has yet to be understood with high precision at PeV energies. A distinct event with a deposited energy above $10^6$ GeV was found in the new two-year sample, in addition to the one event previously found in the seven-year EHE neutrino search. These two events represent a neutrino flux that is incompatible with predictions for a cosmogenic neutrino flux and are considered to be an astrophysical background in the current study. The obtained limit is the most stringent to date in the energy range between $5\times 10^6$ and $5\times 10^{10}$ GeV. This result constrains neutrino models predicting a three-flavor neutrino flux of $E_{\nu }^2{\varphi }_{{\nu }_e+{\nu }_{\mu }+{\nu }_{\tau }}\simeq 2\times 10^{-8}\mathrm{GeV}/{\mathrm{cm}}^2\sec \mathrm{sr}$ at $10^9\mathrm{GeV}$. A significant part of the parameter-space for EHE neutrino production scenarios assuming a proton-dominated composition of ultra-high-energy cosmic rays is excluded.

    ↳ astro-ph.HEhep-exhep-phPRD(2018)·326 citations
15. 15*

    PandaX-II Constraints on Spin-Dependent WIMP-Nucleon Effective Interactions

    Jingkai Xia · Abdusalam Abdukerim · Xun Chen · Yunhua Chen · Xiangyi Cui · Deqing Fang · Changbo Fu · Karl Giboni · Franco Giuliani · Linhui Gu · Xuyuan Guo · Zhifan Guo and 48 other authors

    We present PandaX-II constraints on candidate WIMP-nucleon effective interactions involving the nucleon or WIMP spin, including, in addition to standard axial spin-dependent (SD) scattering, various couplings among vector and axial currents, magnetic and electric dipole moments, and tensor interactions. The data set corresponding to a total exposure of 54-ton-days is reanalyzed to determine constraints as a function of the WIMP mass and isospin coupling. We obtain WIMP-nucleon cross section bounds of $1.6\times 10^{-41}\mathrm{c}{\mathrm{m}}^2$ and $9.0\times 10^{-42}\mathrm{c}{\mathrm{m}}^2$ ($90\%$ c.l.) for neutron-only SD and tensor coupling, respectively, for a mass $M_{\mathrm{WIMP}}\sim 40\mathrm{GeV}/c^2$. The SD limits are the best currently available for $M_{\mathrm{WIMP}}>40\mathrm{GeV}/c^2$. We show that PandaX-II has reached a sensitivity sufficient to probe a variety of other candidate spin-dependent interactions at the weak scale.

    ↳ hep-exhep-phPLB(2019)·110 citations
16. 16*

    Planar ringlike vortices

    D. Bazeia🇧🇷 · M.A. Marques🇧🇷 · D. Melnikov🇧🇷

    We investigate the presence of vortex structures in generalized Maxwell-Higgs and Chern-Simons-Higgs models in the three-dimensional spacetime. Despite the important difference between the Maxwell and Chern-Simons dynamics, we have been able to introduce first order differential equations that solve the equations of motion for static and rotationally symmetric field configurations. In both cases, solutions of the first order equations engender minimum energy, and we have found vortex configurations whose internal structure unveils interesting and unusual ringlike profile.

    ↳ hep-thcond-mat.supr-conhep-phnlin.PSPLB(2018)·17 citations
17. 17*

    Probing primordial non-Gaussianity with 21 cm fluctuations from minihalos

    Toyokazu Sekiguchi🇯🇵 · Tomo Takahashi🇯🇵 · Hiroyuki Tashiro🇯🇵 · Shuichiro Yokoyama🇯🇵

    We investigate future constraints on primordial local-type non-Gaussianity from 21 cm angular power spectrum from minihalos. We particularly focus on the trispectrum of primordial curvature perturbations which are characterized by the non-linearity parameters ${\tau }_{\mathrm{NL}}$ and $g_{\mathrm{NL}}$. We show that future measurements of minihalo 21 cm angular power spectrum can probe these non-linearity parameters with an unprecedented precision of ${\tau }_{\mathrm{NL}}\sim 30$ and $g_{\mathrm{NL}}\sim 2\times 10^3$ for Square Kilometre Array (SKA) and ${\tau }_{\mathrm{NL}}\sim 0.6$ and $g_{\mathrm{NL}}\sim 8\times 10^2$ for Fast Fourier Transform Telescope (FFTT). These levels of sensitivity would give significant implications for models of the inflationary Universe and the origin of cosmic density fluctuations.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2019)·17 citations
18. 18*

    Finite resonance widths influence the thermal-model description of hadron yields

    Volodymyr Vovchenko🇩🇪 · Mark I. Gorenstein🇺🇦 · Horst Stoecker🇩🇪

    Different scenarios for modeling resonances in a thermal model description of hadron yields measured in heavy-ion collisions are explored: the zero-width approximation, the energy independent Breit-Wigner scheme, and the energy dependent Breit-Wigner (eBW) scheme. Application of the eBW scheme leads to a notable suppression in the proton yields, stemming mainly from a reduced feeddown from $\Delta$ resonances because of the threshold effects. A significantly improved agreement of thermal model with hadron yields measured in Pb-Pb collisions at $\sqrt{s_{{}_{NN}}}=2.76$ TeV by the ALICE collaboration is obtained in the eBW scheme at $T\simeq 155$ MeV, indicating a possible resolution of the so-called 'proton anomaly'. The results obtained show that there are significant systematic uncertainties in the thermal model due to the modeling of broad resonances.

    ↳ nucl-thhep-phPRC(2018)·72 citations
19. 19*

    On the merger rate of primordial black holes: effects of nearest neighbours distribution and clustering

    Guillermo Ballesteros🇪🇸 · Pasquale D. Serpico🇫🇷 · Marco Taoso🇮🇹

    One of the seemingly strongest constraints on the fraction of dark matter in the form of primordial black holes (PBH) of $\mathcal{O}$(10)$M_{\odot }$ relies on the merger rate inferred from the binary BH merger events detected by LIGO/Virgo. The robustness of these bounds depends however on the accuracy with which the formation of PBH binaries in the early Universe can be described. We revisit the standard estimate of the merger rate, focusing on a couple of key ingredients: the spatial distribution of nearest neighbours and the initial clustering of PBHs associated to a given primordial power spectrum. Overall, we confirm the robustness of the results presented in the literature in the case of a narrow mass function (which constrain the PBH fraction of dark matter to be $f_{\mathrm{PBH}}\lesssim 0.001-0.01$). The initial clustering of PBHs might have an effect tightening the current constraint, but only for very broad mass functions, corresponding to wide bumps in the primordial power spectra extending at least over a couple of decades in $k$-space.

    ↳ astro-ph.COhep-phJCAP(2018)·128 citations
20. 20*

    Ordered arrays of Baryonic tubes in the Skyrme model in (3+1) dimensions at finite density

    Fabrizio Canfora🇨🇱

    A consistent ansatz for the Skyrme model in (3+1)-dimensions which is able to reduce the complete set of Skyrme field equations to just one equation for the profile in situations in which the Baryon charge can be arbitrary large is introduced: moreover, the field equation for the profile can be solved explicitly. Such configurations describe ordered arrays of Baryonic tubes living in flat space-times at finite density. The plots of the energy density (as well as of the Baryon density) clearly show that the regions of maximal energy density have the shape of a tube: the energy density and the Baryon density depend periodically on two spatial directions while they are constant in the third spatial direction. Thus, these topologically non-trivial crystal-like solutions can be intepreted as configurations in which most of the energy density and the baryon density are concentrated within tube-shaped regions. The positions of the energy-density peaks can be computed explicitly and they manifest a clear crystalline order. A non-trivial stability test is discussed.

    ↳ hep-thhep-phnucl-thEPJC(2018)·57 citations
21. 21*

    Roberge-Weiss endpoint and chiral symmetry restoration in $N_f=2+1$ QCD

    Claudio Bonati🇮🇹 · Enrico Calore🇮🇹 · Massimo D'Elia🇮🇹 · Michele Mesiti🇬🇧 · Francesco Negro🇮🇹 · Francesco Sanfilippo🇮🇹 · Sebastiano Fabio Schifano🇮🇹 · Giorgio Silvi🇩🇪 · Raffaele Tripiccione🇮🇹

    We investigate the fate of the Roberge-Weiss endpoint transition and its connection with the restoration of chiral symmetry as the chiral limit of $N_f=2+1$ QCD is approached. We adopt a stout staggered discretization on lattices with $N_t=4$ sites in the temporal direction; the chiral limit is approached maintaining a constant physical value of the strange-to-light mass ratio and exploring three different light quark masses, corresponding to pseudo-Goldstone pion masses $m_{\pi }\simeq 100,70$ and 50 MeV around the transition. A finite size scaling analysis provides evidence that the transition remains second order, in the 3D Ising universality class, in all the explored mass range. The residual chiral symmetry of the staggered action also allows us to investigate the relation between the Roberge-Weiss endpoint transition and the chiral restoration transition as the chiral limit is approached: our results, including the critical scaling of the chiral condensate, are consistent with a coincidence of the two transitions in the chiral limit; however we are not able to discern the symmetry controlling the critical behavior, because the critical indexes relevant to the scaling of the chiral condensate are very close to each other for the two possible universality classes (3D Ising or O(2)).

    ↳ hep-lathep-phhep-thPRD(2019)·37 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.