Fri·Jan 24, 2020Friday·January 24, 2020

1. 01*

   Search for decaying heavy dark matter in an effective interaction framework: a comparison of $\gamma$-ray and radio observations

   Avirup Ghosh🇮🇳 · Arpan Kar🇮🇳 · Biswarup Mukhopadhyaya🇮🇳

   We investigate and compare the possibilities of observing decaying dark matter (DM) in $\gamma$-ray and radio telescopes. The special emphasise of the study is on a scalar heavy DM particle with mass in the trans-TeV range. DM decays, consistent with existing limits on the life time, are assumed to be driven by higher dimensional effective operators. We consider both two-body decays of a scalar dark particle and a dark sector having three-body decays, producing two standard model particles. It is found that the Fermi-LAT data on isotropic $\gamma$-ray background provides the best constraints so far, although the CTA telescope may be more effective for decays where one or two photons are directly produced. In all cases, deeper probes of the effective operators are possible in the upcoming SKA radio telescope with a few hundred hours of observation, using the radio synchrotron flux coming from energetic electrons produced in the decay cascades within dwarf spheroidal galaxies. Finally, we estimate how the SKA can constrain the parameter space spanned by the galactic magnetic field and the diffusion coefficient, if observations consistent with $\gamma$-ray data actually take place.

   hep-phastro-ph.HEJCAP(2020)·7 citations
2. 02*

   Gradient Tomography of Jet Quenching in Heavy-Ion Collisions

   Yayun He🇨🇳 · Long-Gang Pang🇨🇳 · Xin-Nian Wang🇨🇳

   Transverse momentum broadening and energy loss of a propagating parton are dictated by the space-time profile of the jet transport coefficient $\hat{q}$ in a dense QCD medium. The spatial gradient of $\hat{q}$ perpendicular to the propagation direction can lead to a drift and asymmetry in parton transverse momentum distribution. Such an asymmetry depends on both the spatial position along the transverse gradient and path length of a propagating parton as shown by numerical solutions of the Boltzmann transport in the simplified form of a drift-diffusion equation. In high-energy heavy-ion collisions, this asymmetry with respect to a plane defined by the beam and trigger particle (photon, hadron or jet) with a given orientation relative to the event plane is shown to be closely related to the transverse position of the initial jet production in full event-by-event simulations within the linear Boltzmann transport model. Such a gradient tomography can be used to localize the initial jet production position for more detailed study of jet quenching and properties of the quark-gluon plasma along a given propagation path in heavy-ion collisions.

   hep-phnucl-thPRL(2020)·55 citations
3. 03*

   Relic Density of Asymmetric Dark Matter with Sommerfeld enhancement

   Aihemaitijiang Abudurusuli🇨🇳 · Hoernisa Iminniyaz🇨🇳

   We investigate the evolution of abundance of the asymmetric thermal Dark Matter when its annihilation rate at chemical decoupling is boosted by the Sommerfeld enhancement. Then we discuss the effect of kinetic decoupling on relic abundance of asymmetric Dark Matter when the interaction rate depends on the velocity. Usually the relic density of asymmetric Dark Matter is analyzed in the frame of chemical decoupling. Indeed after decoupling from the chemical equilibrium, asymmetric Dark Matter particles and anti--particles were still in kinetic equilibrium for a while. It has no effect on the case of $s-$wave annihilation since there is no temperature dependence in this case. However, the kinetic decoupling has impacts for the case of $p-$wave annihilation and Sommerfeld enhanced $s-$ and $p-$wave annihilations. We investigate in which extent the kinetic decoupling affects the relic abundances of asymmetric Dark Matter particle and anti--particle in detail. We found the constraints on the cross section and asymmetry factor by using the observational data of relic density of Dark Matter.

   hep-phCPC(2021)·1 citation
4. 04*

   Study of semileptonic decay of ${\bar{B}}_s^0\to \varphi l^{+}{l}^{-}$ in QCD sum rule

   Ying-Quan Peng🇨🇳 · Mao-Zhi Yang🇨🇳

   In this work we study the semi-leptonic decay of ${\bar{B}}_s^0\to \varphi l^{+}{l}^{-}$($l=e,\mu ,\tau$) with QCD sum rule method. We calculate the ${\bar{B}}_s^0\to \varphi$ translation form factors relevant to this semi-leptonic decay, then the branching ratios of ${\bar{B}}_s^0\to \varphi l^{+}{l}^{-}$($l=e,\mu ,\tau$) decays are calculated with the form factors obtained here. Our result for the branching ratio of ${\bar{B}}_s^0\to \varphi {\mu }^{+}{\mu }^{-}$ agrees very well with the recent experimental data. For the unmeasured decay modes such as ${\bar{B}}_s^0\to \varphi e^{+}{e}^{-}$ and ${\bar{B}}_s^0\to \varphi {\tau }^{+}{\tau }^{-}$, we give theoretical predictions.

   hep-phCommun.Theor.Phys.(2020)·2 citations
5. 05*

   Collinear resummations for the non-linear evolution in QCD at high energy

   B. Ducloué🇫🇷 · E. Iancu🇫🇷 · A.H. Mueller🇺🇸 · G. Soyez🇫🇷 · D.N. Triantafyllopoulos🇮🇹

   When computed to next-to-leading order in perturbative QCD, the non-linear Balitsky-Kovchegov (BK) equation for the high-energy evolution of the dipole-hadron scattering appears to be unstable. We show that this instability can be avoided by using the rapidity of the dense hadronic target (instead of that of the dilute dipole projectile) as the evolution time. Using this variable, we construct a collinearly-improved version of the BK equation, where the dominant radiative corrections to the kernel -- those enhanced by double collinear logarithms -- are resummed to all orders.

   hep-phNPA(2021)·0 citations
6. 06*

   On lower bound of relaxation time for massless fluid in presence of magnetic field

   Sarthak Satapathy🇮🇳 · Jayanta Dey🇮🇳 · Prashant Murmu🇮🇳 · Sabyasachi Ghosh🇮🇳

   Due to lowest possible quantum fluctuation, shear viscosity to entropy density ratio never reach to zero, rather has some lower bound (0.08 approx). Here, we have attempted to link our calculation, based on relaxation time approximation for massless relativistic fluid, with that value and interestingly found a lower and also an upper limit of relaxation time.

   hep-phnucl-thDAE Symp.Nucl.Phys.(2019)·0 citations
7. 07*

   Matter vs. vacuum oscillations at long baseline accelerator neutrino experiments

   Suman Bharti🇮🇳 · Ushak Rahaman🇿🇦 · S. Uma Sankar🇮🇳

   The neutrino oscillation probabilities at the long-baseline accelerator neutrino experiments are expected to be modified by matter effects. We search for evidence of such modification in the data of T2K and NO$\nu$A, by fitting the data to the hypothesis of (a) matter modified oscillations and (b) vacuum oscillations. We find that vacuum oscillations provide as good a fit to the data as matter modified oscillations. Even extended runs of T2K and NO$\nu$A, with 5 years in neutrino mode $(5\nu )$ and five years in anti-neutrino mode $(5\bar{\nu })$, can {\bf not} make a $3\sigma$ distinction between vacuum and matter modified oscillations. The proposed experiment DUNE, with neutrino and anti-neutrino runs of 5 years each $(5\nu +5\bar{\nu })$, can rule out vacuum oscillations by itself at $5\sigma$ if the hierarchy is normal. If the hierarchy is inverted, a $5\sigma$ discrimination against vacuum oscillations requires the combination of $(5\nu +5\bar{\nu })$ runs of T2K, \nova and DUNE.

   hep-phhep-exMod.Phys.Lett.A(2021)·7 citations
8. 08*

   Strong decays of strange quarkonia in a corrected 3P0 model

   J. N. de Quadros🇧🇷 · D. T. da Silva🇧🇷 · M. L. L. da Silva🇧🇷 · D. Hadjimichef🇧🇷

   Extensively applied to both light and heavy meson decay and standing as one of the most successful strong decay models is the ${}^3{P}_0$ model, in which $q\bar{q}$ pair production is the dominant mechanism. In this paper we evaluate strong decay amplitudes and partial widths of strange $S$ and $D$ state mesons, namely $\varphi (1020)$, $\varphi (1680)$, $\varphi (2050)$, ${\varphi }_1(1850)$, ${\varphi }_2(1850)$ and ${\varphi }_3(1850)$, in the bound-state corrected ${}^3{P}_0$ decay model (C${}^3{P}_0$). The C${}^3{P}_0$ model is obtained in the context of the Fock-Tani formalism, which is a mapping technique.

   hep-phnucl-thPRC(2020)·6 citations
9. 09*

   Effects of bulk symmetry breaking on AdS/QCD predictions

   Domenec Espriu🇪🇸 · Alisa Katanaeva🇪🇸

   We put forward a new bottom-up AdS/QCD holographic model bearing a distinct treatment of the pion fields. We argue that a standard approach to the pion description is neither transparent nor totally satisfactory. In the paper we provide a new one based on a broadened realization of some holographic principles. The reasoning and the effect of these modifications are explained in detail. The resulting model has a different set of parameters than the standard AdS/QCD case. We use them to calculate an extensive list of QCD quantities and find a rather good agreement with the experimental data.

   hep-phhep-thPRD(2020)·4 citations
10. 10*

    \nu \bar{\nu} -Pair Synchrotron Emission in Neutron-Star Matter based on a Relativistic Quantum Approach

    Tomoyuki Maruyama A. Baha Balantekin · Myung-Ki Cheoun · Toshitaka Kajino · Grant J. Mathews

    We study the neutrino anti-neutrino pair synchrotron emission from electrons and protons in a relativistic quantum approach. This process occurs only under a strong magnetic field, and it is considered to be one of effective processes for neutron star cooling. In this work we calculate the luminosity of the neutrino anti-neutrino pairs emitted from neutron-star-matter with a magnetic field of about 10^{15} G. We find that the energy loss is much larger than that of the modified Urca process. The neutrino anti-neutrino pair emission processes in strong magnetic fields is expected to contribute significantly to the cooling of the magnetars.

    hep-phnucl-thPLB(2020)·6 citations
11. 11*

    Bulk medium evolution has considerable effects on jet observables

    Yasuki Tachibana🇺🇸 · Chun Shen🇺🇸 · Abhijit Majumder🇺🇸

    We consider the case, in QCD, of a single jet propagating within a strongly interacting fluid, of finite extent. Interactions lead to the appearance of a source of energy-momentum within the fluid. The remnant jet that escapes the container is analyzed along with portions of the medium excited by the jet. We study the effect of a static versus a semi-realistic expanding medium, with jets traveling inward versus outward. We consider the medium response via recoils in partonic scatterings based on a weakly-coupled description and its combination with hydrodynamical medium response based on a strongly-coupled description, followed by incorporation into a jet. The effects of these limits on the reconstructed energy, momentum and mass of the jet, as a function of the angle away from the original parton direction are studied. It is demonstrated that different flow velocity configurations in the medium produce considerable differences in jet observables. This work highlights the importance of accurate dynamical modeling of the soft medium as a foundation on which to calculate jet modification, and casts skepticism on results obtained without such modeling.

    ↳ nucl-thhep-phnucl-exPRC(2022)·43 citations
12. 12*

    Efficient solution of the multi-channel Lüscher determinant condition through eigenvalue decomposition

    Antoni J. Woss🇬🇧 · David J. Wilson🇬🇧 · Jozef J. Dudek🇺🇸

    We present a method for efficiently finding solutions of Lüscher's quantisation condition, the equation which relates two-particle scattering amplitudes to the discrete spectrum of states in a periodic spatial volume of finite extent such as that present in lattice QCD. The approach proposed is based on an eigenvalue decomposition in the space of coupled-channels and partial-waves, which proves to have several desirable and simplifying features that are of great benefit when considering problems beyond simple elastic scattering of spinless particles. We illustrate the method with a toy model of vector-vector scattering featuring a high density of solutions, and with an application to explicit lattice QCD energy level data describing $J^P=1^{-}$ and $1^{+}$ scattering in several coupled channels.

    ↳ hep-lathep-phPRD(2020)·36 citations
13. 13*

    Renormalizability of leading order covariant chiral nucleon-nucleon interaction

    Chun-Xuan Wang🇨🇳 · Li-Sheng Geng🇨🇳 · Bingwei Long🇨🇳

    In this work, we study the renormalization group invariance (RGI) of the recently proposed covariant power counting (PC) scheme in the case of nucleon-nucleon scattering [Chin.Phys. C42 (2018) 014103] at leading order (LO). We show that unlike the LO Weinberg case, RGI is satisfied in the ${}^3{P}_0$ channel, because a term of $p{p}^{\prime }$ appears naturally in the covariant PC scheme at LO. Another interesting feature is that the ${}^1{S}_0$ and ${}^3{P}_1$ channels are correlated. Fixing the two relevant low energy constants by fitting to the ${}^1{S}_0$ phase shifts at $T_{lab.}=10$ and $25$ MeV with a cutoff $\Lambda$ of $400-650$ MeV, the ${}^3{P}_1$ phase shifts can be described relatively well. In the limit of $\Lambda \to \infty$, the ${}^1{S}_0$ channel becomes cutoff independent, while RGI is lost in the ${}^3{P}_1$ channel, consistent with the Wigner bound and the previous observation that the ${}^3{P}_1$ channel better be treated perturbatively. As for the ${}^1{P}_1$ and ${}^3{S}_1$-${}^3{D}_1$ channels, RGI is satisfied, similar to the Weinberg approach.

    ↳ nucl-thhep-phCPC(2021)·20 citations
14. 14*

    Goldstino spectrum in an ultracold Bose-Fermi mixture with explicitly broken supersymmetry

    Hiroyuki Tajima🇯🇵 · Yoshimasa Hidaka🇯🇵 · Daisuke Satow🇯🇵

    We theoretically investigate a supersymmetric collective mode called Goldstino in a Bose-Fermi mixture. The explicit supersymmetry breaking, which is unavoidable in cold atom experiments, is considered. We derive the Gell-Mann--Oakes-Renner (GOR) relation for the Goldstino, which gives the relation between the energy gap at the zero momentum and the explicit breaking term. We also numerically evaluate the gap of Goldstino above the Bose-Einstein condensation temperature within the random phase approximation (RPA). While the gap obtained from the GOR relation coincides with that in the RPA for the mass-balanced system, there is a deviation from the GOR relation in the mass-imbalanced system. We point out the deviation becomes large when the Goldstino pole is close to the branch point, although it is parametrically a higher order with respect to the mass-imbalanced parameter. To examine the existence of the goldstino pole in realistic cold atomic systems, we show how the mass-imbalance effect appears in ${}^6$Li-${}^7$Li, ${}^{40}$K-${}^{41}$K, and ${}^{173}$Yb-${}^{174}$Yb mixtures. Furthermore, we analyze the Goldstino spectral weight in a ${}^{173}$Yb-${}^{174}$Yb mixture with realistic interactions and show a clear peak due to the Goldstino pole. As a possibility to observe the Goldstino spectrum in cold atom experiments, we discuss the effects of the Goldstino pole on the fermionic single-particle excitation as well as the relationship between the GOR relation and Tan's contact.

    ↳ cond-mat.quant-gashep-phPRResearch(2021)·10 citations
15. 15*

    Skewness, kurtosis and the 5th and 6th order cumulants of net baryon-number distributions from lattice QCD confront high-statistics STAR data

    A. Bazavov🇺🇸 · D. Bollweg🇩🇪 · H.-T. Ding🇨🇳 · P. Enns🇩🇪 · J. Goswami🇩🇪 · P. Hegde🇮🇳 · O. Kaczmarek🇩🇪 · F. Karsch🇩🇪 · R. Larsen🇺🇸 · Swagato Mukherjee🇺🇸 · H. Ohno🇯🇵 · P. Petreczky🇺🇸 and 3 other authors

    We present new results on up to $6^{th}$ order cumulants of net baryon-number fluctuations at small values of the baryon chemical potential, ${\mu }_B$, obtained in lattice QCD calculations with physical values of light and strange quark masses. Representation of the Taylor expansions of higher order cumulants in terms of the ratio of the two lowest order cumulants, $M_B/{\sigma }_B^2={\chi }_1^B(T,{\mu }_B)/{\chi }_2^B(T,{\mu }_B)$, allows for a parameter free comparison with data on net proton-number cumulants obtained by the STAR Collaboration in the Beam Energy Scan at RHIC. We show that recent high statistics data on skewness and kurtosis ratios of net proton-number distributions, obtained at beam energy $\sqrt{s_{{}_{NN}}}=54.4$ GeV, agree well with lattice QCD results on cumulants of net baryon-number fluctuations close to the pseudo-critical temperature, $T_{pc}({\mu }_B)$, for the chiral transition in QCD. We also present first results from a next-to-leading order expansion of $5^{th}$ and $6^{th}$ order cumulants on the line of pseudo-critical temperatures.

    ↳ hep-lathep-phnucl-exnucl-thPRD(2020)·211 citations
16. 16*

    Testing MSW effect in supernova explosion with neutrino event rates

    Kwang-Chang Lai🇹🇼 · C. S. Jason Leung🇹🇼 · Guey-Lin Lin🇹🇼

    Flavor transition mechanisms of supernova (SN) neutrinos during their propagation deserve a close scrutiny. We present a method to verify Mikheyev-Smirnov-Wolfenstein (MSW) effect during the propagation of SN neutrinos from the SN core to the Earth. The non-MSW scenarios to be distinguished from the MSW one are the incoherent flavor transition probability for neutrino propagation in the vacuum and the flavor equalization induced by fast flavor conversions. Our approach involves studying the time evolution of neutrino event rates in liquid argon, liquid scintillation, and water Cherenkov detectors. The liquid argon detector is sensitive to ${\nu }_e$ flux while liquid scintillation and water Cherenkov detectors can measure ${\bar{\nu }}_e$ flux through inverse $\beta$ decay process. The flux of ${\nu }_e$ (${\bar{\nu }}_e$) is a linear combination of ${\nu }_e$ (${\bar{\nu }}_e$) and ${\nu }_{\mu ,\tau }$ (${\bar{\nu }}_{\mu ,\tau }$) fluxes from the source with the weighting of each component dictated by the flavor transition mechanism. Using currently available simulations for SN neutrino emissions, the time evolution of ${\nu }_e\mathrm{Ar}$ and ${\bar{\nu }}_e$ inverse $\beta$ decay event rates and the corresponding cumulative event fractions are calculated up to $t=100\mathrm{ms}$ in DUNE, JUNO, and Hyper-Kamiokande detectors, respectively. It is shown that the area under the cumulative time distribution curve from $t=0$ to $t=100\mathrm{ms}$ in each detector and their ratio can be used to discriminate different flavor transition scenarios of SN neutrinos.

    ↳ astro-ph.HEhep-phPRD(2023)·6 citations
17. 17*

    Centrality fluctuations and decorrelations in heavy-ion collisions

    Jiangyong Jia🇺🇸 · Chunjian Zhang🇺🇸 · Jun Xu🇨🇳

    The centrality or the number of initial-state sources $V$ of the system produced in heavy ion collision is a concept that is not uniquely defined and subject to significant theoretical and experimental uncertainties. We argue that a more robust connection between the initial-state sources with final-state multiplicity could be established from the event-by-event multiplicity correlation between two subevents separated in pseudorapidity, $N_a$ vs $N_b$. This correlation is sensitive to two main types of centrality fluctuations (CF): 1) particle production for each source $p(n)$ which smears the relation between $V$ and $N_a$ used for experimental centrality, and 2) decorrelations between the sources in the two subevents $V_b$ and $V_a$. The CF is analyzed in terms of cumulants of $V_b$ and $N_b$ as a function of $N_a$, i.e. experimental centrality is defined with $N_a$. We found that the mean values $⟨V_b{⟩}_{N_a}$ and $⟨N_b{⟩}_{N_a}$ increase linearly with $N_a$ in mid-central collisions, but flatten out in ultra-central collisions. Such non-linear behavior is sensitive to the centrality resolution of $N_a$. In the presence of centrality decorrelations, the scaled variances $⟨(\delta V_b{)}^2⟩/⟨V_b⟩$ and $⟨(\delta N_b{)}^2⟩/⟨N_b⟩$ are found to decrease linearly with $N_a$ in mid-central collisions, while the $p(n)$ leads to another sharp decrease in the ultra-central region. The higher-order cumulants of $V_b$ and $N_b$ show interesting but rather complex behaviors which deserve further studies. Our results suggest that one can use the cumulants of the two-dimensional multiplicity correlation, especially the mean and variance, to constrain the particle production mechanism as well as the longitudinal fluctuations of the initial-state sources.

    ↳ nucl-thhep-phnucl-exPRResearch(2020)·17 citations
18. 18*

    Exploring Longitudinal Observables with 3+1D IP-Glasma

    Scott McDonald🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦

    We present a formulation of the initial state of heavy ion collisions that generalizes the 2+1D boost invariant IP-Glasma \cite{Schenke:2012wb} to 3+1D through JIMWLK rapidity evolution of the pre-collision Wilson lines. The rapidity dependence introduced by the JIMWLK evolution leads us to modify the initial condition for the gauge fields, and to solve Gauss' law iteratively in order to allow for temporal evolution on a 3-dimensional lattice. While the transverse physics of QGP has been studied nearly exhaustively, the effect of longitudinal fluctuations introduced by the JIMWLK evolution has yet to be studied in detail phenomenologically. Hence, we couple our 3+1D IP-Glasma model to MUSIC+UrQMD, for completely 3+1D simulations of heavy ion collisions. Specifically, we consider Pb-Pb collisions at $\sqrt{s}=2.76\mathrm{TeV}$ and study the rapidity dependence of the charged hadron $v_n(\eta )$ via the $\eta$-dependent flow factorization ratios $r_n({\eta }_a,{\eta }_b)$ as measured by CMS \cite{Khachatryan:2015oea}, as well as the charged hadron multiplicity $d{N}_{ch}/d\eta$.

    ↳ nucl-thhep-exhep-phNPA(2021)·28 citations
19. 19*

    On Effective Theory of Superfluid Phonons

    Lasha Berezhiani🇩🇪

    It is shown that the standard effective field theory of non-relativistic superfluids, which includes only the leading order action in derivative expansion, is in general inadequate for studying supersonic processes. Namely, for a proper treatment of the latter the phonons with momenta greater than $m{c}_s$ are relevant at times (with $m$ being the mass of the superfluid constituent and $c_s$ denoting the sound-speed), which lie beyond the regime of validity of the naive effective theory mentioned above. This is demonstrated on a concrete example by recovering the known expression for the friction force as a process of radiating phonons by a supersonic perturber. In particular, when the impurity is heavier than superfluid constituents, it is indeed necessary to extend the non-relativistic effective theory of superfluids to include high-derivative corrections. For the light perturber, however, there is a window of velocities for which high-derivative corrections are irrelevant.

    ↳ hep-thcond-mat.quant-gashep-phPLB(2020)·16 citations
20. 20*

    Anti-Deuterons and Anti-Helium Nuclei from Annihilating Dark Matter

    Ilias Cholis🇺🇸 · Tim Linden🇸🇪 · Dan Hooper🇺🇸

    Recent studies of the cosmic-ray antiproton-to-proton ratio have identified an excess of $\sim$10-20 GeV antiprotons relative to the predictions of standard astrophysical models. Intriguingly, the properties of this excess are consistent with the same range of dark matter models that can account for the long-standing excess of $\gamma$-rays observed from the Galactic Center. Such dark matter candidates can also produce significant fluxes of anti-deuterium and anti-helium nuclei. Here we study the production and transport of such particles, both from astrophysical processes as well as from dark matter annihilation. Importantly, in the case of AMS-02, we find that Alfvénic reacceleration (i.e., diffusion in momentum space) can boost the expected number of $\bar{\mathrm{d}}$ and ${}^3\overline{\text{He}}$ events from annihilating dark matter by an order of magnitude or more. For relatively large values of the Alfvén speed, and for dark matter candidates that are capable of producing the antiproton and $\gamma$-ray excesses, we expect annihilations to produce a few anti-deuteron events and about one anti-helium event in six years of AMS-02 data. This is particularly interesting in light of recent reports from the AMS-02 Collaboration describing the detection of a number of anti-helium candidate events.

    ↳ astro-ph.HEastro-ph.COhep-phPRD(2020)·30 citations
21. 21*

    Singlets in the tensor product of an arbitrary number of Adjoint representations of SU(3)

    Prarit Agarwal · June Nahmgoong

    We propose a set of 4 recurrence relations whose linear combination gives the number of group invariants, equivalently the dimension of the invariant subspace, in the tensor product of an arbitrary number of adjoint representations of the SU(3) Lie Group.

    ↳ math.RThep-phhep-thmath.GR3 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.