Mon·Aug 17, 2020Monday·August 17, 2020

1. 01*

   Statistical interpretation of sterile neutrino oscillation searches at reactors

   Pilar Coloma🇪🇸 · Patrick Huber🇺🇸 · Thomas Schwetz🇩🇪

   A considerable experimental effort is currently under way to test the persistent hints for oscillations due to an eV-scale sterile neutrino in the data of various reactor neutrino experiments. The assessment of the statistical significance of these hints is usually based on Wilks' theorem, whereby the assumption is made that the log-likelihood is ${\chi }^2$-distributed. However, it is well known that the preconditions for the validity of Wilks' theorem are not fulfilled for neutrino oscillation experiments. In this work we derive a simple asymptotic form of the actual distribution of the log-likelihood based on reinterpreting the problem as fitting white Gaussian noise. From this formalism we show that, even in the absence of a sterile neutrino, the expectation value for the maximum likelihood estimate of the mixing angle remains non-zero with attendant large values of the log-likelihood. Our analytical results are then confirmed by numerical simulations of a toy reactor experiment. Finally, we apply this framework to the data of the Neutrino-4 experiment and show that the null hypothesis of no-oscillation is rejected at the 2.6\,$\sigma$ level, compared to 3.2\,$\sigma$ obtained under the assumption that Wilks' theorem applies.

   hep-phhep-exnucl-exnucl-thEPJC(2021)·38 citations
2. 02*

   Nonperturbative quark-antiquark interactions in mesonic form factors

   Edward Shuryak🇺🇸 · Ismail Zahed🇺🇸

   The existing theory of hard exclusive QCD processes is based on two assumptions: (i) $factorization$ into a $hardblock$ times light front distribution amplitudes (DA's); (ii) use of perturbative gluon exchanges within the hard block. However, unlike DIS and jet physics, the characteristic momentum transfer $Q$ involved in the factorized block is not large enough for this theory to be phenomenologically successful. In this work, we revisit the latter assumption (ii), by explicitly calculating the $instanton-induced$ contributions to the hard block, and show that they contribute substantially to the vector, scalar and gravitational form factors of the pseudoscalar, scalar and vector mesons, over a wide range of momentum transfer.

   hep-phhep-lathep-thnucl-thPRD(2021)·27 citations
3. 03*

   Soft Wall holographic model for the minimal Composite Higgs

   Domenec Espriu🇪🇸 · Alisa Katanaeva🇪🇸

   We reassess employing the holographic technique to the description of 4D minimal composite Higgs model with $SO(5)\to SO(4)$ global symmetry breaking pattern. The particular 5D bottom-up holographic treatment is inspired by previous work in the context of QCD and it allows to study spin one and spin zero resonances. The resulting spectrum consists of the states transforming under the unbroken $SO(4)$ subgroup and those with quantum numbers in the $SO(5)/SO(4)$ coset. The spin one states are arranged in linear radial trajectories, and the states from the broken subgroup are generally heavier. The spin zero states from the coset space correspond to the four massless Goldstone bosons in 4D. One of them takes the role of the Higgs boson. Restrictions derived from the experimental constraints (Higgs couplings, $S$ parameter, etc.) are then implemented and we conclude that the model is able to accommodate new vector resonances with masses in the range $2$ TeV to $3$ TeV without encountering phenomenological difficulties. The couplings governing the production of these new states in the processes of the SM gauge boson scattering are also estimated. The method can be extended to other breaking patterns.

   hep-phhep-thPRD(2021)·5 citations
4. 04*

   Light neutralino dark matter in $U(1{)}_X$SSM

   Shu-Min Zhao · Guo-Zhu Ning · Jing-Jing Feng · Hai-Bin Zhang · Tai-Fu Feng

   The $U(1{)}_X$ extension of the minimal supersymmetric standard model(MSSM) is called as $U(1{)}_X$SSM with the local gauge group $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y\times U(1{)}_X$. $U(1{)}_X$SSM has three singlet Higgs superfields beyond MSSM. In $U(1{)}_X$SSM, the mass matrix of neutralino is $8\times 8$, whose lightest mass eigenstate possesses cold dark matter characteristic. Supposing the lightest neutralino as dark matter candidate, we study the relic density. For dark matter scattering off nucleus, the cross sections including spin-independent and spin-dependent are both researched. In our numerical results, some parameter space can satisfy the constraints from the relic density and the experiments of dark matter direct detection.

   hep-phNPB(2021)·11 citations
5. 05*

   The QCD odderon in elastic (anti)proton scattering

   M.A.Braun🇷🇺

   The C-odd amplitude for the elastic $pp$ and $p\bar{p}$ scattering due to the exchange of the QCD odderon proposed by J.Bartels, L.N.Lipatov and G.P. Vacca is calculated with the Fukugita-Kwiecinski proton impact factor. The found amplitude is very small and cannot be felt in the differential cross-sections at 2.76 and 1.96 Tev respectively.

   hep-phEPJC(2021)·1 citation
6. 06*

   Bounds on Very Weakly Interacting Ultra Light Scalar and Pseudoscalar Dark Matter from Quantum Gravity

   Xavier Calmet🇬🇧 · Folkert Kuipers🇬🇧

   In this paper we consider very weakly interacting and ultra light scalar and pseudoscalar dark matter candidates. We show that quantum gravity has important implications for such models and that the masses of the singlet scalar and pseudoscalar fields must be heavier than $3\times 10^{-3}$ eV. However, if they are gauged, their masses could be much lighter and as light as $10^{-22}\mathrm{eV}$. The existence of new gauge forces in the dark matter sector can thus be probed by atomic clocks or quantum sensors experiments.

   hep-phhep-thEPJC(2020)·9 citations
7. 07*

   On the second Gegenbauer moment of $\rho$-meson distribution amplitude

   Maxim V. Polyakov🇩🇪 · Hyeon-Dong Son🇩🇪

   Using the soft pion theorem, crossing, and the dispersion relations for the two pion distribution amplitude ($2\pi$DA) we argue that the second Gegenbauer moment the $\rho$-meson DA ($a_2^{(\rho )}$) most probably is negative. This result is at variance with the majority of the model calculations for $a_2^{(\rho )}$. Using the instanton theory of the QCD vacuum, we computed $a_2^{(\rho )}$ at a low normalisation point and obtain for the ratio $a_2^{(\rho )}/M_3^{(\pi )}$ {\it definitely negative value} in the range of $a_2^{(\rho )}/M_3^{(\pi )}\in [-2,-1]$. The range of values corresponds to a generous variation of the parameters of the instanton vacuum. The value of the second Gegenbauer moment of pion DA is positive in the whole range and is compatible with its the most advanced lattice measurement. It seems that the topologically non-trivial field configurations in the QCD vacuum (instantons) lead to qualitatively different shapes of the pion and the $\rho$-meson DAs.

   hep-phhep-exhep-latPRD(2020)·10 citations
8. 08*

   Increasing effective intensity of soft strong interactions

   S.M. Troshin🇷🇺 · N.E. Tyurin🇷🇺

   We suggest definition of effective interaction intensity for soft hadron collisions and discuss its energy dependence in the preasymptotic region. Practical importance of this quantity consists in separation of rising interaction radius from effective interaction intensity increase both contributing to the total cross--section growth. It would be helpful for understanding the origin of this growth at the accelerator energies. The essential feature is that the effective interaction intensity is an experimentally measurable quantity.

   hep-phInt.J.Mod.Phys.A(2020)·2 citations
9. 09*

   An interface between the POWHEG BOX and MadGraph5_aMC@NLO

   Paolo Nason🇮🇹 · Carlo Oleari🇮🇹 · Marco Rocco🇮🇹 · Marco Zaro🇮🇹

   In this paper we present a framework for developing POWHEG BOX generators using MadGraph5_aMC@NLO for the computation of the matrix elements. Within this framework, all the flexibility of MadGraph5_aMC@NLO for the generation of matrix elements for Standard Model processes and for several of its extensions can be exploited, as well as all features of the POWHEG BOX framework, including the possibility of multijet merging without a merging scale (using the so called MiNLO approach). As a proof of concept, we develop a generator for the production of a spin-0 Higgs-like boson in association with up to two jets, with CP-violating couplings.

   hep-phEPJC(2020)·11 citations
10. 10*

    Leptogenesis from low-energy CP violation in minimal left-right symmetric model

    Xinyi Zhang🇨🇳 · Jiang-Hao Yu🇨🇳 · Bo-Qiang Ma🇨🇳

    We perform a thermal unflavored leptogenesis analysis on minimal left-right symmetric models with discrete left-right symmetry identified as generalized parity or charge conjugation. When left-right symmetry is unbroken in the lepton Yukawa sector, the neutrino Dirac coupling matrix is completely determined by neutrino masses and mixing angles, allowing CP violation needed to generate leptogenesis totally resides in the low-energy sector. With two lepton asymmetry generation ways, both type I and mixed type I$+$II neutrino mass generation mechanisms are considered. After solving the Boltzmann equations numerically, we find that the low-energy CP phases in the lepton mixing matrix can successfully produce the observed baryon asymmetry, and in some cases, the Dirac CP phase can be the only source of CP violation. Finally, we discuss the interplay among low-energy CP phase measurements, leptogenesis, and neutrinoless double beta decay. We show that the viable models for successful leptogenesis can be probed in next-generation neutrinoless double-beta decay experiments.

    hep-phNPB(2022)·8 citations
11. 11*

    LHC Signals for KK Graviton from an Extended Warped Extra Dimension

    Kaustubh Agashe🇺🇸 · Majid Ekhterachian🇺🇸 · Doojin Kim🇺🇸 · Deepak Sathyan🇺🇸

    We analyze signals at the Large Hadron Collider (LHC) from production and decay of Kaluza-Klein (KK) gravitons in the context of "extended" warped extra-dimensional models, where the standard model (SM) Higgs and fermion fields are restricted to be in-between the usual ultraviolet/Planck brane and a $\sim O(10)$ TeV (new, "intermediate") brane, whereas the SM gauge fields (and gravity) propagate further down to the $\sim O(TeV)$ infrared brane. Such a framework suppresses flavor violation stemming from KK particle effects, while keeping the KK gauge bosons and gravitons accessible to the LHC. We find that the signals from KK graviton are significantly different than in the standard warped model. This is because the usually dominant decay modes of KK gravitons into top quark, Higgs and longitudinal $W/Z$ particles are suppressed by the above spatial separation between these two sets of particles, thus other decay channels are allowed to shine themselves. In particular, we focus on two novel decay channels of the KK graviton. The first one is the decay into a pair of radions, each of which decays (dominantly) into a pair of SM gluons, resulting in a resonant 4-jet final state consisting of two pairs of dijet resonance. On the other hand, if the radion is heavier and/or KK gluon is lighter, then the KK graviton mostly decays into a KK gluon and a SM gluon. The resulting KK gluon has a significant decay branching fraction into radion and SM gluon, thereby generating (again) a 4-jet signature, but with a different underlying event topology, i.e., featuring now three different resonances. We demonstrate that the High-Luminosity LHC (HL-LHC) has sensitivity to KK graviton of (up to) $\sim 4$ TeV in both channels, whereas it is unlikely to have sensitivity in the standard dijet resonance search channel from KK graviton decay into two gluons.

    hep-phhep-exJHEP(2020)·24 citations
12. 12*

    Integral Reduction with Kira 2.0 and Finite Field Methods

    Jonas Klappert🇩🇪 · Fabian Lange🇩🇪 · Philipp Maierhöfer🇩🇪 · Johann Usovitsch🇩🇪

    We present the new version 2.0 of the Feynman integral reduction program Kira and describe the new features. The primary new feature is the reconstruction of the final coefficients in integration-by-parts reductions by means of finite field methods with the help of FireFly. This procedure can be parallelized on computer clusters with MPI. Furthermore, the support for user-provided systems of equations has been significantly improved. This mode provides the flexibility to integrate Kira into projects that employ specialized reduction formulas, direct reduction of amplitudes, or to problems involving linear system of equations not limited to relations among standard Feynman integrals. We show examples from state-of-the-art Feynman integral reduction problems and provide benchmarks of the new features, demonstrating significantly reduced main memory usage and improved performance w.r.t. previous versions of Kira.

    hep-phhep-thComput.Phys.Commun.(2021)·465 citations
13. 13*

    Ultralight Fermionic Dark Matter

    Hooman Davoudiasl🇺🇸 · Peter B. Denton🇺🇸 · David A. McGady🇸🇪

    Conventional lore from Tremaine and Gunn excludes fermionic dark matter lighter than a few hundred eV, based on the Pauli exclusion principle. We highlight a simple way of evading this bound with a large number of species that leads to numerous non-trivial consequences. In this scenario there are many distinct species of fermions with quasi-degenerate masses and no couplings to the standard model. Nonetheless, gravitational interactions lead to constraints from measurements at the LHC, of cosmic rays, of supernovae, and of black hole spins and lifetimes. We find that the LHC constrains the number of distinct species, bosons or fermions lighter than $\sim 500$ GeV, to be $N\lesssim 10^{62}$. This, in particular, implies that roughly degenerate fermionic dark matter must be heavier than $\sim 10^{-14}$ eV, which thus relaxes the Tremaine-Gunn bound by $\sim 16$ orders of magnitude. Slightly weaker constraints applying to masses up to $\sim 100$ TeV exist from cosmic ray measurements while various constraints on masses $\lesssim 10^{-10}$ eV apply from black hole observations. We consider a variety of phenomenological bounds on the number of species of particles. Finally, we note that there exist theoretical considerations regarding quantum gravity which could impose more severe constraints that may limit the number of physical states to $N\lesssim 10^{32}$.

    hep-phastro-ph.COhep-thPRD(2021)·56 citations
14. 14*

    Covariantizing Phase Space

    Andrew J. Larkoski🇺🇸 · Tom Melia🇯🇵

    We covariantize calculations over the manifold of phase space, establishing Stokes' theorem for differential cross sections and providing new definitions of familiar observable properties like infrared and collinear safety. Through the introduction of explicit coordinates and a metric we show phase space is isomorphic to the product space of a simplex and a hypersphere, and we identify geometric phenomena that occur when its dimensions are large. These results have implications for fixed order subtraction schemes, machine learning in particle physics and high-multiplicity heavy ion collisions.

    hep-phnucl-thPRD(2020)·24 citations
15. 15*

    Mechanical Quantum Sensing in the Search for Dark Matter

    Daniel Carney🇺🇸 · Gordan Krnjaic🇺🇸 · David C. Moore🇺🇸 · Cindy A. Regal🇺🇸 · Gadi Afek🇺🇸 · Sunil Bhave🇺🇸 · Benjamin Brubaker🇺🇸 · Thomas Corbitt🇺🇸 · Jonathan Cripe🇺🇸 · Nicole Crisosto🇺🇸 · Andrew Geraci🇺🇸 · Sohitri Ghosh🇺🇸 and 23 other authors

    Numerous astrophysical and cosmological observations are best explained by the existence of dark matter, a mass density which interacts only very weakly with visible, baryonic matter. Searching for the extremely weak signals produced by this dark matter strongly motivate the development of new, ultra-sensitive detector technologies. Paradigmatic advances in the control and readout of massive mechanical systems, in both the classical and quantum regimes, have enabled unprecedented levels of sensitivity. In this white paper, we outline recent ideas in the potential use of a range of solid-state mechanical sensing technologies to aid in the search for dark matter in a number of energy scales and with a variety of coupling mechanisms.

    ↳ physics.ins-detastro-ph.COhep-exhep-ph+1Quantum Sci.Technol.(2021)·176 citations
16. 16*

    Reheating in holographic cosmology and connecting to $\Lambda$-MSSM constructions for particle physics

    Horatiu Nastase🇧🇷

    In this paper we model the transition from the non-geometric holographic cosmology regime, to the usual radiation dominated (RD) cosmology, known as reheating in the case of (perturbative) inflation. We find that we can easily transition into any MSSM construction of intersecting D6-branes, via ${\alpha }^{\prime }$ corrections in the 3 dimensional field theory as well as in cosmology, followed by cosmological reheating via S-NS5-branes. Moreover, we can naturally obtain the (true) cosmological constant $\Lambda$ of the observed order of magnitude. The resulting supersymmetry breaking is just outside the currently observed energies. The model is consistent with large (TeV scale) extra dimensions, but it prefers smaller ones, and the string scale is generically low.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2021)·1 citation
17. 17*

    Searching for primordial helical magnetic fields

    M. Kachelriess🇳🇴 · B.C. Martinez🇳🇴

    The presence of non-zero helicity in intergalactic magnetic fields (IGMF) has been suggested as a clear signature for their primordial origin. We extend a previous analysis of diffuse Fermi-LAT gamma-ray data from 2.5 to more than 11 years and show that a hint for helical magnetic fields in the 2.5 year data was a statistical fluctuation. Then we examine the detection prospects of helical magnetic fields using individual sources as, e.g., TeV gamma-ray blazars. We find that a detection is challenging employing realistic models for the cascade evolution, the IGMF and the detector resolution in our simulations.

    ↳ astro-ph.HEhep-phPRD(2020)·6 citations
18. 18*

    Search for new phenomena in top quark interactions

    Kirill Skovpen (on behalf of the ATLAS and CMS Collaborations)🇧🇪

    The study of the processes with the production of top quarks represents a unique possibility to test the standard model (SM) predictions and probe the new physics effects. Potential deviations from the SM expectations are parametrized within the framework of the Effective Field Theory (EFT). The latest EFT results from ATLAS and CMS experiments are presented. Dedicated studies of processes with flavour-changing neutral currents are also discussed.

    ↳ hep-exhep-phPoS(2021)·0 citations
19. 19*

    Palatini-Higgs inflation with non-minimal derivative coupling

    Ioannis D. Gialamas🇬🇷 · Alexandros Karam🇪🇪 · Angelos Lykkas🇬🇷 · Thomas D. Pappas🇨🇿

    The predictions of standard Higgs inflation in the framework of the metric formalism yield a tensor-to-scalar ratio $r\sim 10^{-3}$ which lies well within the expected accuracy of near-future experiments $\sim 10^{-4}$. When the Palatini formalism is employed, the predicted values of $r$ get highly-suppressed $r\sim 10^{-12}$ and consequently a possible non-detection of primordial tensor fluctuations will rule out only the metric variant of the model. On the other hand, the extremely small values predicted for $r$ by the Palatini approach constitute contact with observations a hopeless task for the foreseeable future. In this work, we propose a way to remedy this issue by extending the action with the inclusion of a generalized non-minimal derivative coupling term between the inflaton and the Einstein tensor of the form $m^{-2}(\varphi )G_{\mu \nu }{\nabla }^{\mu }\varphi {\nabla }^{\nu }\varphi$. We find that with such a modification, the Palatini predictions can become comparable with the ones obtained in the metric formalism, thus providing ample room for the model to be in contact with observations in the near future.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2020)·69 citations
20. 20*

    $DK$ $I=0,$ $D\bar{K}$ $I=0,1$ scattering and the $D_{s0}^{\ast }(2317)$ from lattice QCD

    Gavin K. C. Cheung🇬🇧 · Christopher E. Thomas🇬🇧 · David J. Wilson🇬🇧 · Graham Moir🇬🇧 · Michael Peardon🇮🇪 · Sinéad M. Ryan🇮🇪

    Elastic scattering amplitudes for $I=0$ $DK$ and $I=0,1$ $D\bar{K}$ are computed in $S$, $P$ and $D$ partial waves using lattice QCD with light-quark masses corresponding to $m_{\pi }=239$ MeV and $m_{\pi }=391$ MeV. The $S$-waves contain interesting features including a near-threshold $J^P=0^{+}$ bound state in $I=0$ $DK$, corresponding to the $D_{s0}^{\ast }(2317)$, with an effect that is clearly visible above threshold, and suggestions of a $0^{+}$ virtual bound state in $I=0$ $D\bar{K}$. The $S$-wave $I=1$ $D\bar{K}$ amplitude is found to be weakly repulsive. The computed finite-volume spectra also contain a deeply-bound $D^{\ast }$ vector resonance, but negligibly small $P$-wave $DK$ interactions are observed in the energy region considered; the $P$ and $D$-wave $D\bar{K}$ amplitudes are also small. There is some evidence of $1^{+}$ and $2^{+}$ resonances in $I=0$ $DK$ at higher energies.

    ↳ hep-lathep-phJHEP(2021)·96 citations
21. 21*

    Delta baryons and diquark formation in the cores of neutron stars

    German Malfatti🇦🇷 · Milva G. Orsaria🇦🇷 · Ignacio F. Ranea-Sandoval🇦🇷 · Gustavo A. Contrera🇦🇷 · Fridolin Weber🇺🇸

    We investigate the hadron-quark phase transition in cold neutron stars in light of (i) the observed limits on the maximum-mass of heavy pulsars, (ii) constraints on the tidal properties inferred from the gravitational waves emitted in binary neutron-star mergers, and (iii) mass and radius constraints derived from the observation of hot spots on neutron star observed with NICER. Special attention is directed to the possible presence of $\Delta (1232)$ baryons in neutron star matter. Our results indicate that this particle could make up a large fraction of the baryons in neutron stars and thus have a significant effect on the properties of such objects, particularly on their radii. This is partially caused by the low density appearance of $\Delta$s for a wide range of theoretically defensible sets of meson-hyperon, SU(3) ESC08 model, and meson-$\Delta$ coupling constants. The transition of hadronic matter to quark matter, treated in the 2SC+s condensation phase, is found to occur only in neutron stars very close to the mass peak. Nevertheless, quark matter may still constitute an appreciable fraction of the stars' total matter if the phase transition is treated as Maxwell-like (sharp), in which case the neutron stars located beyond the gravitational mass peak would remain stable against gravitational collapse. In this case, the instability against gravitational collapse is shifted to a new (terminal) mass different from the maximum-mass of the stellar sequence, giving rise to stable compact objects with the same gravitational masses as those of the neutron stars on the traditional branch, but whose radii are smaller by up to 1 km. All models for the equation of state of our study fall comfortably within the bound established very recently by Annala {\it et al.} (Nature Physics, 2020)

    ↳ astro-ph.HEhep-phnucl-thPRD(2020)·68 citations
22. 22*

    Anomaly and Cobordism Constraints Beyond Grand Unification: Energy Hierarchy

    Juven Wang🇺🇸

    A recent work [2006.16996] suggests that a 4d nonperturbative global anomaly of mod 16 class hinting a possible new hidden gapped topological sector beyond the Standard Model (SM) and Georgi-Glashow $su(5)$ Grand Unified Theory (GUT) with 15n chiral Weyl fermions and a discrete ${\mathbb{Z}}_{4,X}$ symmetry of $X=5(\mathbf{B}-\mathbf{L})-4Y$. This ${\mathbb{Z}}_{16}$ class global anomaly is a mixed gauge-gravitational anomaly between the discrete $X$ and spacetime backgrounds. The new topological sector has a GUT scale high energy gap, below its low energy encodes either a 4d noninvertible topological quantum field theory (TQFT), or a 5d short-range entangled invertible TQFT, or their combinations. This hidden topological sector provides the 't Hooft anomaly matching of the missing sterile right-handed neutrinos (3 generations of 16th Weyl fermions), and possibly also accounts for the Dark Matter sector. In the SM and $su(5)$ GUT, the discrete $X$ can be either a global symmetry or gauged. In the $so(10)$ GUT, the $X$ must become gauged, the 5d TQFT becomes noninvertible and long-range entangled (which can couple to dynamical gravity). In this work, we further examine the anomaly and cobordism constraints at higher energy scales above the $su(5)$ GUT to $so(10)$ GUT and $so(18)$ GUT (with Spin(10) and Spin(18) gauge groups precisely). We also find [2006.16996]'s proposal on new hidden gapped topological sectors can be consistent with anomaly matching under the energy/mass hierarchy. Novel ingredients along tuning the energy include various energy scales of anomaly-free symmetric mass generation (i.e., Kitaev-Wen mechanism), the Topological Mass/Energy Gap from anomalous symmetric topological order (attachable to a 5d ${\mathbb{Z}}_{4,X}$-symmetric topological superconductor), possible topological quantum phase transitions, and Ultra Unification that includes GUT with new topological sectors.

    ↳ hep-thcond-mat.supr-conhep-phmath.AT26 citations
23. 23*

    Symmetries from Locality. III. Massless Spin 2 Gravitons and Time Translations

    Mark P. Hertzberg🇺🇸 · Jacob A. Litterer🇺🇸

    We relax the assumption of time translation and Lorentz boost symmetry in theories involving massless spin 2 gravitons, while maintaining a basic notion of locality that there is no instantaneous signaling at a distance. We project out longitudinal modes, leaving only two degrees of freedom of the graviton. Our previous work, which assumed time translation symmetry, found that the Lorentz boost symmetry is required to ensure locality at leading order. In this work, without assuming time translations or Lorentz boosts, we show that locality of the exchange action between matter sources demands that massless spin 2, at leading order, organizes into Einstein-Hilbert plus a Gauss-Bonnet term with a prefactor that is constrained to be a particular function of time; while in the matter sector we recover time translation and Lorentz boost symmetry. Finally, we comment on whether the time dependence of the Gauss-Bonnet prefactor may be forbidden by going to higher order in the analysis and we mention that other possibilities are anticipated if graviton mass terms are included.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2020)·4 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.