Tue·Jun 2, 2020Tuesday·June 2, 2020

1. 01*

   Yet another lesson on the stability conditions in multi-Higgs potentials

   Igor P. Ivanov🇵🇹 · Francisco Vazão🇵🇹

   We discuss a rather common but often unnoticed pitfall which arises when deriving the bounded-from-below (BFB) conditions in multi-Higgs models with softly broken global symmetries. Namely, necessary and sufficient BFB conditions derived for the case with an exact symmetry can be ruined by introducing soft symmetry breaking terms. Using $S_4$ and $A_4$-symmetric three-Higgs-doublet models as an example, we argue that all published necessary and sufficient BFB conditions, even those which are correct for the exactly symmetric case, are no longer sufficient if soft symmetry breaking is added. Using the geometric formalism, we derive the exact necessary and sufficient BFB conditions for the 3HDM with the symmetry group $S_4$, either exact or softly broken, and review the situation for the $A_4$-symmetric case.

   hep-phJHEP(2020)·17 citations
2. 02*

   New bounds on macroscopic scalar-field topological defects from non-transient signatures due to environmental dependence and spatial variations of the fundamental constants

   Yevgeny V. Stadnik🇯🇵

   We point out that in models of macroscopic topological defects composed of one or more scalar fields that interact with standard-model fields via scalar-type couplings, the back-action of ambient matter on the scalar field(s) produces an environmental dependence of the fundamental constants of nature, as well as spatial variations of the fundamental constants in the vicinity of dense bodies such as Earth due to the formation of a "bubble-like" defect structure surrounding the dense body. In sufficiently dense environments, spontaneous symmetry breaking may be inhibited altogether for ${\varphi }^2$ interactions, potentially delaying the cosmological production of topological defects. We derive bounds on non-transient variations of the fundamental constants from torsion-pendulum experiments that search for equivalence-principle-violating forces, experiments comparing the frequencies of ground- and space-based atomic clocks, as well as ground-based clocks at different heights in the recent Tokyo Skytree experiment, and measurements comparing atomic and molecular transition frequencies in terrestrial and low-density astrophysical environments. Our results constrain the present-day mass-energy fraction of the Universe due to a network of infinite domain walls produced shortly after the BBN or CMB epochs to be ${\Omega }_{\text{walls},0}\ll 10^{-10}$ for the symmetron model with a ${\varphi }^4$ potential and ${\varphi }^2$ interactions, improving over CMB quadrupolar temperature anisotropy bounds by at least 5 orders of magnitude. Our newly derived bounds on domain walls with ${\varphi }^2$ interactions via their effects of non-transient variations of the fundamental constants are significantly more stringent than previously reported clock- and cavity-based limits on passing domain walls via transient signatures and previous bounds from different types of non-transient signatures, under the same set of assumptions.

   hep-phastro-ph.COgr-qcphysics.atom-phPRD(2020)·32 citations
3. 03*

   Quark level and hadronic contributions to the electric dipole moment of charged leptons in the standard model

   Yasuhiro Yamaguchi🇯🇵 · Nodoka Yamanaka🇯🇵

   We evaluate the electric dipole moment of charged leptons in the standard model, where the complex phase of the Cabibbo-Kobayashi-Maskawa matrix is the only source of CP violation. We first prove that, at the quark-gluon level, it is suppressed by a factor of $m_b^2{m}_c^2{m}_s^2$ at all orders of perturbation due to the Glashow-Iliopoulos-Maiani mechanism. We then calculate the hadronic long distance contribution generated by vector mesons at one-loop level. The $|\Delta S|=1$ weak hadronic interaction is derived using the factorization, and the strong interaction is modeled by the hidden local symmetry framework. We find that the electric dipole moments of charged leptons obtained from this hadronic mechanism are much larger than the perturbative four-loop level quark-gluon process, by several orders of magnitude.

   hep-phhep-exnucl-thPRD(2021)·83 citations
4. 04*

   Prospect of the Electroweak Scale Right-handed neutrino model in the Lifetime Frontier

   Shreyashi Chakdar🇺🇸 · P.Q Hung🇺🇸

   Motivated by the null results of the BSM searches in the post-Higgs era of the LHC, our current approach is to look for new physics shifting from theory driven search strategies to signature driven ones. One possible direction might come from investigating the long-lived particles (LLPs) present in various theoretical scenarios through the newly formed Lifetime frontier. In this talk, I discuss a non-sterile right-handed neutrino model consisting of EW-scale Majorana masses, having signals with large displaced vertices arising in both the fermion and scalar sectors. The characteristic features in this model, the displaced vertices, i.e. several charged tracks originating from a position separated from the proton interaction point has to be greater than a mm and can be as long as order of centimeters. These events originating from the decays of the mirror fermions produce promising signatures at the LHC environment due to the low associated backgrounds. We discuss the experimental implications and possible search strategies in this framework and LHCs potential to unravel these underlying events.

   hep-ph2 citations
5. 05*

   Indirect Detection of Dark Matter in the Galaxy

   Rebecca K. Leane🇺🇸

   I present a short overview of the latest developments in indirect searches for dark matter using gamma rays, X-rays, charged cosmic rays, micro waves, radio waves, and neutrinos. I briefly outline key past, present, and future experiments and their search strategies. In several searches there are exciting anomalies which could potentially be emerging dark matter signals. I discuss these anomalous signals, and some future prospects to determine their origins.

   hep-phastro-ph.HE71 citations
6. 06*

   The Effects of the Tsallis Entropy in the Proton Internal Pressure

   S. D. Campos🇧🇷 · A. M. Amarante (Universidade Federal de São Carlos)🇧🇷

   In this paper, one discusses the effects of the Tsallis entropy on the radial pressure distribution in the proton. Using a damped confinement potential the pressure distribution is obtained from the Tsallis entropy approach, being the entropic-index $\omega$ connected with the proton temperature concerning some transition temperature. Then, the approach allows the study of the proton thermal evolution up to the Quark-Gluon Plasma regime. The von Laue stability condition, arising from the pressure distribution results in positive and negative energy regions. An analogy between the results for the radial pressure distribution and the proton-proton and the antiproton-proton total cross section is performed. The negative energy region is identified with the odderon exchange while the positive represents the pomeron exchange dominance above some transition energy $\sqrt{s_c}$. The hollowness effect is also discussed in terms of the results obtained and the proposed analogy.

   hep-phhep-thInt.J.Mod.Phys.A(2020)·2 citations
7. 07*

   Resolved $1/m_b$ contributions to $\bar{B}\to X_{s,d}{\ell }^{+}{\ell }^{-}$ and $\bar{B}\to X_s\gamma$

   Michael Benzke🇩🇪 · Tobias Hurth🇩🇪

   In view of the importance of the nonperturbative resolved contributions for the overall uncertainties of the two inclusive penguin decays $\bar{B}\to X_s\gamma$ and $\bar{B}\to X_{s,d}{\ell }^{+}{\ell }^{-}$ we reanalyse these contributions using new estimates of moments of the subleading shape functions and of other input parameters. Within a systematic approach we find a significant reduction of the nonperturbative uncertainties in the inclusive decay $\bar{B}\to X_{s,d}{\ell }^{+}{\ell }^{-}$, but a much less pronounced reduction in the inclusive decay $\bar{B}\to X_s\gamma$ compared to a recent analysis on the resolved contributions to the inclusive decay $\bar{B}\to X_s\gamma$. We identify the reasons for this discrepancy.

   hep-phPRD(2020)·20 citations
8. 08*

   Tau $g-2$ at $e^{-}{e}^{+}$ colliders with momentum dependent form factor

   Hieu Minh Tran🇻🇳 · Yoshimasa Kurihara🇯🇵

   The deviation between the standard model prediction and the measurement of the muon g-2 is currently at 3-4 sigma (can be up to 7 sigma in the upcoming experiment E989). If new physics is responsible for such discrepancy, it is expected that the new contributions to tau g-2 are even larger than that for muon due to its large mass. In spite of that, the tau g-2 is much more difficult to be directly measured because of its short lifetime. In this paper, we consider the effect of the tau g-2 at $e^{-}{e}^{+}$ colliders in a model independent way. Using the tau pair production channel at the Large Electron Position Collider (LEP), we have found the allowed range for the new physics contribution of the tau g-2 assuming a $q^2$-dependence ansatz for the magnetic form factor. In our analysis, we take into account the standard model one-loop correction as well as the initial state photon radiation. We have also investigated the prospect at future $e^{-}{e}^{+}$ colliders, and determine the expected allowed range for the new physics contribution to the tau g-2. Given the proposed beam polarization configuration at the International Linear Collider (ILC), we have analyzed the dependence of this allowed range on the integrated luminosity as well as the relative systematic error.

   hep-phEPJC(2021)·9 citations
9. 09*

   Multicomponent dark matter in noncommutative $B-L$ gauge theory

   Cao H. Nam🇻🇳 · Duong Van Loi🇻🇳 · Le Xuan Thuy🇻🇳 · Phung Van Dong🇻🇳

   It is shown that for a higher weak isospin symmetry, $SU(P{)}_L$ with $P\ge 3$, the baryon minus lepton charge $B-L$ neither commutes nor closes algebraically with $SU(P{)}_L$ similar to the electric charge $Q$, which all lead to a $SU(3{)}_C\otimes SU(P{)}_L\otimes U(1{)}_X\otimes U(1{)}_N$ gauge completion, where $X$ and $N$ determine $Q$ and $B-L$, respectively. As a direct result, the neutrinos obtain appropriate masses via a canonical seesaw. While the version with $P=3$ supplies the schemes of single-component dark matter well established in the literature, we prove in this work that the models with $P\ge 4$ provide the novel scenarios of multicomponent dark matter, which contain simultaneously at least $P-2$ stable candidates, respectively. In this setup, the multicomponet dark matter is nontrivially unified with normal matter by gauge multiplets, and their stability is ensured by a residual gauge symmetry which is a remnant of the gauge symmetry after spontaneous symmetry breaking. The three versions with $P=4$ according to the new lepton electric charges are detailedly investigated. The mass spectrum of the scalar sector is diagonalized when the scale of the $U(1{)}_N$ breaking is much higher than that of the usual 3-4-1 symmetry breaking. All the interactions of gauge bosons with fermions and scalars are obtained. We figure out viable parameter regimes given that the multicomponent dark matter satisfies the Planck and (in)direct detection experiments.

   hep-phhep-thJHEP(2020)·18 citations
10. 10*

    A possibility of CPT violation in the Standard Model

    S.A. Larin🇷🇺

    It is shown that there is a possibility of violation of CPT symmetry in the Standard Model which does not contradict to the famous CPT theorem. To check this possibility experimentally it is necessary to increase the precision of measurements of the proton and antiproton mass difference by an order of magnitude

    hep-phEPL(2020)·2 citations
11. 11*

    Electrically charged strange stars with an interacting quark matter equation of state

    V. P. Goncalves🇧🇷 · L. Lazzari🇧🇷

    The properties of electrically charged strange quark stars predicted by an interacting quark matter equation of state (EoS) based on cold and dense perturbative quantum chromodynamics (pQCD) are investigated. The stability of strange stars is analyzed considering different models for the electric charge distribution inside the star as well as for distinct values for the total electric charge. A comparison with the predictions derived using the MIT bag model is also presented. We show that the presence of a net electric charge inside strange stars implies in a larger maximum mass in comparison to their neutral counterparts. Moreover, we demonstrate that the pQCD EoS implies larger values for the maximum mass of charged strange stars, with very heavy charged stars being stable systems against radial oscillations. For an electric charge distribution given by $q(r)=\beta r^3$, the pQCD EoS implies unstable configurations for large values of the renormalization scale as well as for large values of $\beta$, in contrast to the MIT bag model predictions.

    hep-phastro-ph.HEPRD(2020)·28 citations
12. 12*

    Untangling the spin of a dark boson in $Z$ decays

    A. Comelato🇮🇹 · E. Gabrielli🇮🇹

    We analyze the $Z$-boson decay $Z\to \gamma X$ into a photon ($\gamma$) plus a hypothetical light boson ($X$) belonging to a dark or secluded sector. Due to its feeble interactions with Standard Model fields, this dark boson is behaving as missing energy in the detector. We consider for $X$ the cases of spin-1 (massless dark-photon), spin-0 (axion-like), and spin-2 (graviton-like) particles and explore the way to untangle its spin origin. All these scenarios predict a universal signature for this decay, characterized by a single mono-chromatic photon in the $Z$ center of mass, with energy about half of the $Z$ mass, plus a neutrino-like missing energy associated to the $X$ boson. We show that if the $Z\to \gamma X$ signal should be discovered at $e^{+}{e}^{-}$ colliders, the angular distribution of the mono-chromatic photon in $e^{+}{e}^{-}\to Z\to \gamma X$ can provide a clean probe to discriminate between the $J=1$ and alternative $J=0/2$ spin nature of the $X$ dark boson.

    hep-phPRD(2020)·5 citations
13. 13*

    Is the $X17$ composed of four bare quarks?

    Hua-Xing Chen🇨🇳

    When studying tetraquark states using the method of QCD sum rules, we find some tetraquark currents, such as ${\bar{u}}_L{\gamma }_{\mu }{d}_L{\bar{d}}_L{\gamma }^{\mu }{u}_L$ and ${\bar{u}}_L{\gamma }_{\mu }{d}_L{\bar{d}}_R{\gamma }^{\mu }{u}_R$, etc. We calculate their correlation functions using the method of operator product expansion, and find that non-perturbative QCD effects do not contribute much to them. This indicates the possible existence of tetraquark states composed of bare quarks with abnormally small masses. We study the possible assignment of the $X17$ as such a state. We argue that the Atomki experiments might observe a new type of nuclear decay process, where sea quarks take away the extra energy of the nucleus. A unique feature of this tetraquark assignment is that we predict two almost degenerate states with significantly different widths.

    hep-ph14 citations
14. 14*

    Structure and tidal deformability of a hybrid star within the framework of the field correlator method

    S. Khanmohamadi🇮🇷 · H. R. Moshfegh🇮🇷 · S. Atashbar Tehrani🇮🇷

    The structure of hybrid stars within the nonperturbative framework of the field correlator method, extended to zero-temperature limit as a quark model, has been studied. For the hadronic sector, we have used the lowest-order constraint variational method by employing AV18 two-body nucleon-nucleon interaction supplemented by the phenomenological Urbana-type three-body force. For an adapted value of the gluon condensate, G2 = 0:006 GeV4, which gives the critical temperature of about Tc ? 170 MeV, stable hybrid stars with a maximum mass of 2:04M? are predicted. The stability of hybrid star has been investigated for a wide range of gluon condensate value, G2, and quark-antiquark potential, V1. A hybrid equation of state fulfills the constraints on tidal deformability and hence on the radii of the stars, extracted from the binary GW170817. Moreover, tidal deformability for different chirp masses and different binary mass ratios of hybrid stars have been studied. The mass-radius relation satisfies the new constraint obtained from the neutron star interior composition explorer (NICER). A comprehensive analysis on the structure of a hybrid star and also its compactness, tidal Love number, and tidal deformability has been conducted for several parameter sets of the quark equation of state. The influence of different crustal equations of state on the mentioned quantities has been studied. Our calculations suggest the value of quark-antiquark potential, V1, to be around 0.08 GeV. The results achieved in this study are in strong concurrence with the other calculations reported on this subject.

    hep-phastro-ph.HEnucl-thPRD(2020)·10 citations
15. 15*

    Pentaquarks with the $qqs\bar{Q}Q$ configuration in the Chiral Quark Model

    Qi Zhang🇨🇳 · Bing-Ran He🇨🇳 · Jia-Lun Ping🇨🇳

    We study the five-quark system composed of $qqs\bar{Q}Q$ configuration ($q=u$ or $d$, $Q=b$ or $c$), in the framework of the chiral quark model. In consequence, a series of bound states with heavy flavors are predicted by precise five-body dynamical calculations. We found that taking color-octet structure into consideration always provides more bounding energy than color-singlet structure, and the more heavier quark prevents, the easier to form the bound states. We suggest $qqs\bar{b}b$ configuration is a compact $\bar{b}b$-pair surrounded by three other quarks, while $qqs\bar{b}c$, $qqs\bar{c}b$ and $qqs\bar{c}c$ configurations are molecular states.

    hep-phhep-lat34 citations
16. 16*

    $\omega \to 3\pi$ and $\omega {\pi }^0$ transition form factor revisited

    M.Albaladejo🇺🇸 · I. Danilkin🇩🇪 · S. Gonzalez-Solis🇺🇸 · D. Winney🇺🇸 · C.Fernandez-Ramirez🇲🇽 · A. N. Hiller Blin🇺🇸 · V. Mathieu🇪🇸 · M. Mikhasenko🇨🇭 · A. Pilloni🇮🇹 · A. Szczepaniak🇺🇸

    In light of recent experimental results, we revisit the dispersive analysis of the $\omega \to 3\pi$ decay amplitude and of the $\omega {\pi }^0$ transition form factor. Within the framework of the Khuri-Treiman equations, we show that the $\omega \to 3\pi$ Dalitz-plot parameters obtained with a once-subtracted amplitude are in agreement with the latest experimental determination by BESIII. Furthermore, we show that at low energies the $\omega {\pi }^0$ transition form factor obtained from our determination of the $\omega \to 3\pi$ amplitude is consistent with the data from MAMI and NA60 experiments.

    hep-phhep-exEPJC(2020)·30 citations
17. 17*

    Fluctuations of topological charge and chiral density in the early stage of high energy nuclear collisions

    Moran Jia🇨🇳 · Junhong Liu🇨🇳 · Hongfei Zhang🇨🇳 · Marco Ruggieri🇨🇳

    We study systematically the topological charge density and the chiral density correlations in the early stage of high energy nuclear collisions: the intial condition is given by the McLerran-Venugopalan model and the evolution of the gluon fields is studied via the Classical Yang-Mills equations up to proper time $\tau \approx 1$ fm/c for an $SU(2)$ evolving Glasma. Topological charge is related to the gauge invariant $\mathbf{E}\cdot \mathbf{B}$ where $\mathbf{E}$ and $\mathbf{B}$ denote the color-electric and color-magnetic fields, while the chiral density is produced via the chiral anomaly of Quantum Chromodynamics. We study how the correlation lengths are related to the collision energy, and how the correlated domains grow up with proper time in the transverse plane for a boost invariant longitudinal expansion. We estimate the correlation lengths of both quantities, that after a short transient results of the order of the typical energy scale of the model, namely the inverse of the saturation scale. We estimate the proper time for the formation of a steady state in which the production of the chiral density in the transverse plane per unit rapidity slows down, as well as the amount of chiral density that would be present at the switch time between the Classical Yang-Mills evolution and the relativistic transport or hydro for the quark-gluon plasma phase.

    hep-phhep-thnucl-thPRD(2021)·4 citations
18. 18*

    Another SMEFT Story: $Z^{\prime }$ Facing New Results on ${\epsilon }^{\prime }/\epsilon$, $\Delta M_K$ and $K\to \pi \nu \bar{\nu }$

    Jason Aebischer🇺🇸 · Andrzej J. Buras🇩🇪 · Jacky Kumar🇨🇦

    Recently the RBC-UKQCD lattice collaboration presented new results for the hadronic matrix elements relevant for the ratio ${\epsilon }^{\prime }/\epsilon$ in the Standard Model (SM). With the present knowledge of the Wilson coefficients and isospin breaking effects there is still much room for new physics (NP) contributions to ${\epsilon }^{\prime }/\epsilon$ which could both enhance or suppress this ratio to agree with the data. The new SM value for the $K^0-{\bar{K}}^0$ mass difference $\Delta M_K$ from RBC-UKQCD is on the other hand by $2\sigma$ above the data hinting for NP required to suppress $\Delta M_K$. Simultaneously the most recent results for $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ from NA62 and for $K_L\to {\pi }^0\nu \bar{\nu }$ from KOTO still allow for significant NP contributions. We point out that the suppression of $\Delta M_K$ by NP requires the presence of new CP-violating phases with interesting implications for $K\to \pi \nu \bar{\nu }$, $K_S\to {\mu }^{+}{\mu }^{-}$ and $K_L\to {\pi }^0{\ell }^{+}{\ell }^{-}$ decays. Considering a $Z^{\prime }$-scenario within the SMEFT we analyze the dependence of all these observables on the size of NP still allowed by the data on ${\epsilon }^{\prime }/\epsilon$. The NP QCD penguin scenario for ${\epsilon }^{\prime }/\epsilon$ is excluded by SMEFT renormalization group effects in ${\epsilon }_K$ so that NP effects in ${\epsilon }^{\prime }/\epsilon$ are governed by electroweak penguins. We also investigate for the first time whether the presence of a heavy $Z^{\prime }$ with flavour violating couplings could generate through top Yukawa renormalization group effects FCNCs mediated by the SM $Z$-boson. The outcome turns out to be very interesting.

    hep-phhep-exhep-latJHEP(2020)·49 citations
19. 19*

    Unified weak/strong coupling framework for nuclear matter and neutron stars

    Niko Jokela🇫🇮 · Matti Jarvinen🇮🇱 · Govert Nijs🇳🇱 · Jere Remes🇫🇮

    Ab initio methods using weakly interacting nucleons give a good description of condensed nuclear matter up to densities comparable to the nuclear saturation density. At higher densities palpable strong interactions between overlapping nucleons become important; we propose that the interactions will continuously switch over to follow a holographic model in this region. In order to implement this, we construct hybrid equations of state (EoSs) where various models are used for low density nuclear matter, and the holographic V-QCD model is used for non-perturbative high density nuclear matter as well as for quark matter. We carefully examine all existing constraints from astrophysics of compact stars and discuss their implications for the hybrid EoSs. Thanks to the stiffness of the V-QCD EoS for nuclear matter, we obtain a large family of viable hybrid EoSs passing the constraints. We find that quark matter cores in neutron stars are unstable due to the strongly first order deconfinement transition, and predict bounds on the tidal deformability as well as on the radius of neutron stars. By relying on universal relations, we also constrain characteristic peak frequencies of gravitational waves produced in neutron star mergers.

    hep-phastro-ph.HEhep-thnucl-thPRD(2021)·78 citations
20. 20*

    Dark matter relic density from conformally or disformally coupled light scalars

    Sebastian Trojanowski🇬🇧 · Philippe Brax🇫🇷 · Carsten van de Bruck🇬🇧

    Thermal freeze-out is a prominent example of dark matter (DM) production mechanism in the early Universe that can yield the correct relic density of stable weakly interacting massive particles (WIMPs). At the other end of the mass scale, many popular extensions of the Standard Model predict the existence of ultra-light scalar fields. These can be coupled to matter, preferentially in a universal and shift-symmetry-preserving way. We study the impact of such conformal and disformal couplings on the relic density of WIMPs, without introducing modifications to the thermal history of the Universe. This can either result in an additional thermal contribution to the DM relic density or suppress otherwise too large abundances compared to the observed levels. In this work, we assume that the WIMPs only interact with the standard model via the light scalar portal. We use simple models of fermionic or scalar DM, although a similar discussion holds for more sophisticated scenarios, and predict that their masses should be between $\sim 100\text{GeV}$ and several $\text{TeV}$ to comply both with the DM abundance and current bounds on the couplings of the light scalars to matter at the LHC. Future searches will tighten these bounds.

    hep-phastro-ph.COgr-qcPRD(2020)·13 citations
21. 21*

    Dynamical Evidence For a Fifth Force Explanation of the ATOMKI Nuclear Anomalies

    Jonathan L. Feng🇺🇸 · Tim M. P. Tait🇺🇸 · Christopher B. Verhaaren🇺🇸

    Recent anomalies in ${}^8$Be and ${}^4$He nuclear decays can be explained by postulating a fifth force mediated by a new boson $X$. The distributions of both transitions are consistent with the same $X$ mass, 17 MeV, providing kinematic evidence for a single new particle explanation. In this work, we examine whether the new results also provide dynamical evidence for a new particle explanation, that is, whether the observed decay rates of both anomalies can be described by a single hypothesis for the $X$ boson's interactions. We consider the observed ${}^8$Be and ${}^4$He excited nuclei, as well as a ${}^{12}$C excited nucleus; together these span the possible $J^P$ quantum numbers up to spin 1. For each transition, we determine whether scalar, pseudoscalar, vector, or axial vector $X$ particles can mediate the decay, and we construct the leading operators in a nuclear physics effective field theory that describes them. Assuming parity conservation, the scalar case is excluded and the pseudoscalar case is highly disfavored. Remarkably, however, the protophobic vector gauge boson, first proposed to explain only the ${}^8$Be anomaly, also explains the ${}^4$He anomaly within experimental uncertainties. We predict signal rates for other closely related nuclear measurements, which, if confirmed, will provide overwhelming evidence that a fifth force has been discovered.

    hep-phhep-exnucl-exnucl-thPRD(2020)·69 citations
22. 22*

    Reactor Antineutrino Oscillations at Super-Kamiokande

    André de Gouvêa🇺🇸 · Ivan Martinez-Soler🇺🇸

    SuperKamiokande (SK) doped with gadolinium has the capability to efficiently identify electron-antineutrinos through inverse beta-decay. Given the size of SK and the number of nuclear reactors in its vicinity, we argue that SK can observe the oscillations of reactor antineutrinos driven by the so-called solar mass-squared difference $\Delta m_{21}^2$. After only one year of data taking, we estimate that SK can measure $\Delta m_{21}^2$ with enough precision to help inform the current small tension between existing results from KamLAND and solar neutrino experiments.

    hep-phhep-exPLB(2020)·9 citations
23. 23*

    Spin oscillations of neutrinos scattered off a rotating black hole

    Maxim Dvornikov (IZMIRAN)🇷🇺

    Spin oscillations of neutrinos, gravitationally scattered off a black hole (BH), are studied. The cases of nonrotating and rotating BHs are analyzed. We derive the analytic expressions for the transition and survival probabilities of spin oscillations when neutrinos interact with these gravitational backgrounds. The obtained transition probabilities depend on the impact parameter, as well as the neutrino energy and the particle mass. We find that there is a possibility of spin oscillations of ultrarelativistic neutrinos scattering off a rotating BH. Then, considering the neutrino scattering off BH surrounded by background matter, we derive the effective Schrodinger equation for spin oscillations. The numerical solution of this equation is obtained in the case of a supermassive BH with a realistic accretion disk. Spin effects turn out to be negligible in the neutrino scattering in the Schwarzschild metric. In the Kerr metric, we find that the observed neutrino fluxes can be reduced almost 10% because of spin oscillations when ultrarelativistic neutrinos experience gravitational scattering. The neutrino interaction with an accretion disk results in the additional modification of the intensities of outgoing neutrino fluxes. We consider the applications of the obtained results for the neutrino astronomy.

    hep-phastro-ph.HEgr-qcEPJC(2020)·14 citations
24. 24*

    Spin-dependence of Gravity-mediated Dark Matter in Warped Extra-Dimensions

    Miguel G. Folgado🇪🇸 · Andrea Donini🇪🇸 · Nuria Rius🇪🇸

    We study the spin-dependence of Dark Matter (DM) particles which interact gravitationally with the Standard Model (SM) in an extra-dimensional Randall-Sundrum scenario. We assume that both the Dark Matter and the Standard Model are confined to the TeV (Infra-red) brane and only interact via gravitational mediators, namely Kaluza-Klein gravitons and the radion. We analyze the different DM annihilation channels and find that it is possible to achieve the presently observed relic abundance of Dark Matter, ${\Omega }_{\mathrm{DM}}$, within the freeze-out mechanism for DM particles of spin 0, 1/2 and 1. We study the region of the model parameter space for which ${\Omega }_{\mathrm{DM}}$ is achieved and compare it with the different experimental and theoretical bounds. We also consider the impact of the radion in the phenomenology. We find that, for DM particles mass $m_{\mathrm{DM}}\in [1,15]$ TeV, most of the parameter space is excluded by the current constraints or will be excluded by the LHC Run III or by the LHC upgrade, the HL-LHC. The presence of the radion does not modify significantly the non-excluded region. The observed DM relic abundance can still be achieved for DM masses $m_{}\in [4,15]$ TeV and $m_{G_1}<10$ TeV for scalar and vector boson Dark Matter. On the other hand, for spin 1/2 fermion Dark Matter, only a tiny region with $m_{\mathrm{DM}}\in [4,15]$ TeV, $m_{G_1}\in [5,10]$ TeV and $\Lambda >m_{G_1}$ is compatible with theoretical and experimental bounds.

    hep-phastro-ph.HEEPJC(2021)·9 citations
25. 25*

    Quantization of the charge in Coulomb plus harmonic potential

    Yoon-Seok Choun🇰🇷 · Sang-Jin Sin🇰🇷

    We consider two models where the wave equation can be reduced to the effective Schrödinger equation whose potential contains both harmonic and the Coulomb terms, ${\omega }^2{r}^2-a/r$. The equation reduces to the biconfluent Heun's equation, and we find that the charge as well as the energy must be quantized and state dependent. We also find that two quantum numbers are necessary to count radial degrees of freedom and suggest that this is a general feature of differential equation with higher singularity like the Heun's equation.

    hep-phhep-thPTEP(2021)·2 citations
26. 26*

    First Measurement of Differential Charged Current Quasielastic-like ${\nu }_{\mu }$-Argon Scattering Cross Sections with the MicroBooNE Detector

    P. Abratenko · M. Alrashed · R. An · J. Anthony · J. Asaadi · A. Ashkenazi · S. Balasubramanian · B. Baller · C. Barnes · G. Barr · V. Basque · L. Bathe-Peters and 172 other authors

    We report on the first measurement of flux-integrated single differential cross sections for charged-current (CC) muon neutrino (${\nu }_{\mu }$) scattering on argon with a muon and a proton in the final state, ${}^{40}$Ar(${\nu }_{\mu }$,$\mu$p)X. The measurement was carried out using the Booster Neutrino Beam at Fermi National Accelerator Laboratory and the MicroBooNE liquid argon time projection chamber detector with an exposure of 4.59 $\times$ 10${}^{19}$ protons on target. Events are selected to enhance the contribution of CC quasielastic (CCQE) interactions. The data are reported in terms of a total cross section as well as single differential cross sections in final state muon and proton kinematics. We measure the integrated per-nucleus CCQE-like cross section (i.e. for interactions leading to a muon, one proton and no pions above detection threshold) of (4.93 $\pm$ 0.76stat $\pm$ 1.29sys) $\times$ 10${}^{-38}$cm${}^2$, in good agreement with theoretical calculations. The single differential cross sections are also in overall good agreement with theoretical predictions, except at very forward muon scattering angles that correspond to low momentum-transfer events.

    ↳ hep-exhep-phnucl-exnucl-thPRL(2020)·87 citations
27. 27*

    Non supersymmetric femion boson symmetry

    Vaibhav Wasnik🇮🇳

    In this work we present symmetry transformations relating bosons to fermions which cannot be represented as a supersymmetric algebra. We present a symmetry transformation relating a complex scalar and a fermion in four dimensions and construct a theory defined by an action that respects the symmetry quantum mechanically. We next invoke gauge symmetry by adding a gauge field and a corresponding fermion and construct two different symmetry transformations with corresponding actions such that the corresponding theories respect the fermion boson symmetry transformations quantum mechanically. Unlike in a supersymmetric theory, the vacuum energy in the above theories could be negative. Phenomenological implications of the theories are open to research.

    ↳ hep-thhep-ph0 citations
28. 28*

    Analysis of the QCD Kondo phase using random matrices

    Takuya Kanazawa🇯🇵

    We propose a novel random matrix model that describes the QCD Kondo phase. The model correctly implements both the chiral symmetry of light quarks and the SU(2) spin symmetry of heavy quarks. We analytically take the large-N limit with N the matrix size and show that the model has three phases: the pure Kondo phase with no chiral condensate, the pure chirally broken phase with no Kondo condensate, and the coexistence phase. The model predicts that the pairing form of the Kondo condensate in the coexistence phase is significantly altered compared to the pure Kondo phase. For each phase, we rigorously derive the low-energy effective theory of Nambu-Goldstone modes and obtain compact closed expressions for the partition function with external sources. We also include a chiral chemical potential into the model and examine the vacuum structure.

    ↳ hep-thhep-lathep-phnucl-thMod.Phys.Lett.A(2026)·8 citations
29. 29*

    Hubble Sinks In The Low-Redshift Swampland

    Aritra Banerjee🇰🇷 · Haiying Cai🇰🇷 · Lavinia Heisenberg🇨🇭 · Eoin Ó Colgáin🇰🇷 · M. M. Sheikh-Jabbari🇮🇷 · Tao Yang🇰🇷

    Local determinations of the Hubble constant $H_0$ favour a higher value than Planck based on CMB and $\Lambda$CDM. Through a model-independent expansion, we show that low redshift ($z\lesssim 0.7$) data comprising baryon acoustic oscillations (BAO), cosmic chronometers and Type Ia supernovae has a preference for Quintessence models that lower $H_0$ relative to $\Lambda$CDM. In addition, we confirm that an exponential coupling to dark matter cannot alter this conclusion in the same redshift range. Our results leave open the possibility that a coupling in the matter-dominated epoch, potentially even in the dark ages, may yet save $H_0$ from sinking in the string theory Swampland.

    ↳ astro-ph.COhep-phhep-thPRD(2021)·230 citations
30. 30*

    Direct limits on the interaction of antiprotons with axion-like dark matter

    C. Smorra🇯🇵 · Y. V. Stadnik🇩🇪 · P. E. Blessing🇯🇵 · M. Bohman🇯🇵 · M. J. Borchert🇯🇵 · J. A. Devlin🇯🇵 · S. Erlewein🇯🇵 · J. A. Harrington🇯🇵 · T. Higuchi🇯🇵 · A. Mooser🇯🇵 · G. Schneider🇯🇵 · M. Wiesinger🇯🇵 and 9 other authors

    Astrophysical observations indicate that there is roughly five times more dark matter in the Universe than ordinary baryonic matter, with an even larger amount of the Universe's energy content due to dark energy. So far, the microscopic properties of these dark components have remained shrouded in mystery. In addition, even the five percent of ordinary matter in our Universe has yet to be understood, since the Standard Model of particle physics lacks any consistent explanation for the predominance of matter over antimatter. Inspired by these central problems of modern physics, we present here a direct search for interactions of antimatter with dark matter, and place direct constraints on the interaction of ultra-light axion-like particles $-$ one of the dark-matter candidates $-$ and antiprotons. If antiprotons exhibit a stronger coupling to these dark-matter particles than protons, such a CPT-odd coupling could provide a link between dark matter and the baryon asymmetry in the Universe. We analyse spin-flip resonance data acquired with a single antiproton in a Penning trap [Smorra et al., Nature 550, 371 (2017)] in the frequency domain to search for spin-precession effects from ultra-light axions with a characteristic frequency governed by the mass of the underlying particle. Our analysis constrains the axion-antiproton interaction parameter $f_a/C_{\overline{p}}$ to values greater than $0.1$ to $0.6$ GeV in the mass range from $2\times 10^{-23}$ to $4\times 10^{-17}$eV/$c^2$, improving over astrophysical antiproton bounds by up to five orders of magnitude. In addition, we derive limits on six combinations of previously unconstrained Lorentz-violating and CPT-violating terms of the non-minimal Standard Model Extension.

    ↳ physics.atom-phastro-ph.COhep-phNature(2019)·84 citations
31. 31*

    Configurational entropy and spectroscopy of pomeron resonances in dynamical AdS/QCD

    D. Marinho Rodrigues🇧🇷 · R. da Rocha🇧🇷

    Pomeron resonances in AdS/QCD are here studied using the configurational entropy (CE). The concept of CE Regge trajectories, associating the CE of the pomeron resonances with both their spin $J^{PC}$ and to their mass spectra, is used to derive the mass spectra of higher $J^{PC}$ pomeron resonances. For it, the linear, the exponential modified and the anomalous quadratic dilatonic models, each one with linear and logarithmic anomalous corrections, are employed. Several methods are implemented, hybridizing AdS/QCD and established data of lattice QCD.

    ↳ hep-thhep-phEur.Phys.J.Plus(2022)·15 citations
32. 32*

    What can we learn about QCD and collider physics from N=4 super Yang-Mills?

    Johannes M. Henn🇩🇪

    Tremendous ongoing theory efforts are dedicated to developing new methods for QCD calculations. Qualitative rather than incremental advances are needed to fully exploit data still to be collected at the LHC. The maximally supersymmetric Yang-Mills theory ($\mathcal{N}=4$ sYM) shares with QCD the gluon sector, which contains the most complicated Feynman graphs, but at the same time has many special properties, and is believed to be solvable exactly. It is natural to ask what we can learn from advances in $\mathcal{N}=4$ sYM for addressing difficult problems in QCD. With this in mind, we review here several remarkable developments and highlights of recent results in $\mathcal{N}=4$ sYM. This includes all-order results for certain scattering amplitudes, novel symmetries, surprising geometrical structures of loop integrands, novel tools for the calculation of Feynman integrals, and bootstrap methods. While several insights and tools have already been carried over to QCD and have contributed to state-of-the-art calculations for LHC physics, we argue that there is a host of further fascinating ideas waiting to be explored.

    ↳ hep-thhep-exhep-phAnn.Rev.Nucl.Part.Sci.(2021)·41 citations
33. 33*

    Search for the rare decays ${\pi }^{+}\to {\mu }^{+}{\nu }_{\mu }\nu \bar{\nu }$ and ${\pi }^{+}\to e^{+}{\nu }_e\nu \bar{\nu }$

    A. Aguilar-Arevalo🇲🇽 · M. Aoki🇯🇵 · M. Blecher🇺🇸 · D.I. Britton🇬🇧 · D. vom Bruch🇨🇦 · D.A. Bryman🇨🇦 · S. Chen🇨🇳 · J. Comfort🇺🇸 · S. Cuen-Rochin🇨🇦 · L. Doria🇩🇪 · P. Gumplinger🇨🇦 · A. Hussein🇨🇦 and 14 other authors

    The rare pion decays ${\pi }^{+}\to {\mu }^{+}{\nu }_{\mu }\nu \bar{\nu }$ and ${\pi }^{+}\to e^{+}{\nu }_e\nu \bar{\nu }$ are allowed in the Standard Model but highly suppressed. These decays were searched for using data from the PIENU experiment. A first result for $\Gamma ({\pi }^{+}\to {\mu }^{+}{\nu }_{\mu }\nu \bar{\nu })/\Gamma ({\pi }^{+}\to {\mu }^{+}{\nu }_{\mu })<8.6\times 10^{-6}$, and an improved measurement $\Gamma ({\pi }^{+}\to e^{+}{\nu }_e\nu \bar{\nu })/\Gamma ({\pi }^{+}\to {\mu }^{+}{\nu }_{\mu })<1.6\times 10^{-7}$ were obtained.

    ↳ hep-exhep-phPRD(2020)·9 citations
34. 34*

    Correspondence between Israel-Stewart and first-order casual and stable hydrodynamics for the boost-invariant massive case with zero baryon density

    Arpan Das🇵🇱 · Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱

    Exact correspondence between Israel-Stewart theory and first-order causal and stable hydrodynamics is established for the boost-invariant massive case with zero baryon density and the same constant relaxation times used in the shear and bulk sectors. Explicit expressions for the temperature dependent regulators are given for the case of a relativistic massive gas. The stability and causality conditions known in the first-order approach are applied and one finds that one of them is violated in this case.

    ↳ nucl-thhep-phPRD(2020)·19 citations
35. 35*

    The Nelson-Seiberg theorem generalized with nonpolynomial superpotentials

    Zhengyi Li🇨🇳 · Zheng Sun🇨🇳

    The Nelson-Seiberg theorem relates R-symmetries to F-term supersymmetry breaking, and provides a guiding rule for new physics model building beyond the Standard Model. A revision of the theorem gives a necessary and sufficient condition to supersymmetry breaking in models with polynomial superpotentials. This work revisits the theorem to include models with nonpolynomial superpotentials. With a generic R-symmetric superpotential, a singularity at the origin of the field space implies both R-symmetry breaking and supersymmetry breaking. We give a generalized necessary and sufficient condition for supersymmetry breaking which applies to both perturbative and nonperturbative models.

    ↳ hep-thhep-phAdv.High Energy Phys.(2020)·11 citations
36. 36*

    Muon capture rates: Evaluation within the Quasiparticle Random Phase Approximation

    Fedor Simkovic🇸🇰 · Rastislav Dvornicky🇷🇺 · Petr Vogel🇺🇸

    The Quasiparticle Random Phase Approximation (QRPA) is used in evaluation of the total muon capture ratesfor the final nuclei participating in double-beta decay. Several variants of the method are used, depending on the size of the single particle model space used, or treatment of the initial bound muon wave function. The resulting capture rates are all reasonably close to each other. In particular, the variant that appears to be most realistic, results in rates in good agreement with the experimental values. There is no necessity for an empirical quenching of the axial current coupling constant $g_A$. Its standard value $g_A$ = 1.27 seems to be adequate.

    ↳ nucl-thhep-phnucl-exPRC(2020)·20 citations
37. 37*

    Lorentz violating scalar Casimir effect for a $D$-dimensional sphere

    A. Martín-Ruiz🇲🇽 · C. A. Escobar🇲🇽 · A. M. Escobar-Ruiz🇲🇽 · O. J. Franca🇲🇽

    We investigate the Casimir effect, due to the confinement of a scalar field in a $D$-dimensional sphere, with Lorentz symmetry breaking. The Lorentz-violating part of the theory is described by the term $\lambda (u\cdot \partial \varphi {)}^2$, where the parameter $\lambda$ and the background vector $u^{\mu }$ codify the breakdown of Lorentz symmetry. We compute, as a function of $D$, the Casimir stress by using Green's function techniques for two specific choices of the vector $u^{\mu }$. In the timelike case, $u^{\mu }=(1,0,...,0)$, the Casimir stress can be factorized as the product of the Lorentz invariant result times the factor $(1+\lambda {)}^{-1/2}$. For the radial spacelike case, $u^{\mu }=(0,1,0,...,0)$, we obtain an analytical expression for the Casimir stress which nevertheless does not admit a factorization in terms of the Lorentz invariant result. For the radial spacelike case we find that there exists a critical value ${\lambda }_c={\lambda }_c(D)$ at which the Casimir stress transits from a repulsive behavior to an attractive one for any $D>2$. The physically relevant case $D=3$ is analyzed in detail where the critical value ${\lambda }_c{|}_{D=3}=0.0025$ was found. As in the Lorentz symmetric case, the force maintains the divergent behavior at positive even integer values of $D$.

    ↳ hep-thhep-phPRD(2020)·15 citations
38. 38*

    Neural ODE and Holographic QCD

    Koji Hashimoto🇯🇵 · Hong-Ye Hu🇺🇸 · Yi-Zhuang You🇺🇸

    The neural ordinary differential equation (Neural ODE) is a novel machine learning architecture whose weights are smooth functions of the continuous depth. We apply the Neural ODE to holographic QCD by regarding the weight functions as a bulk metric, and train the machine with lattice QCD data of chiral condensate at finite temperature. The machine finds consistent bulk geometry at various values of temperature and discovers the emergent black hole horizon in the holographic bulk automatically. The holographic Wilson loops calculated with the emergent machine-learned bulk spacetime have consistent temperature dependence of confinement and Debye-screening behavior. In machine learning models with physically interpretable weights, the Neural ODE frees us from discretization artifact leading to difficult ingenuity of hyperparameters, and improves numerical accuracy to make the model more trustworthy.

    ↳ hep-thcond-mat.dis-nngr-qchep-phMach.Learn.Sci.Tech.(2021)·38 citations
39. 39*

    Mean lifetime of a false vacuum in terms of the Krylov-Fock non-escape probability

    Michael Maziashvili🇬🇪

    The Krylov-Fock expression of non-decay (or survival) probability, which allows to evaluate the deviations from the exponential decay law (nowadays well established experimentally), is more informative as it readily provides the distribution function for the lifetime as a random quantity. Guided by the well established formalism for describing nuclear alpha decay, we use this distribution function to figure out the mean value of lifetime and its fluctuation rate. This theoretical framework is of considerable interest inasmuch as it allows an experimental verification. Next, we apply the Krylov-Fock approach to the decay of a metastable state at a finite temperature in the framework of thermo-field dynamics. In contrast to the existing formalism, this approach shows the interference effect between the tunnelings from different metastable states as well as between the tunneling and the barrier hopping. This effect looks quite natural in the framework of consistent quantum mechanical description as a manifestation of the "double-slit experiment". In the end we discuss the field theory applications of the results obtained.

    ↳ hep-thhep-phPRD(2020)·0 citations
40. 40*

    $d^{\ast }(2380)$ dibaryon from lattice QCD

    Shinya Gongyo🇯🇵 · Kenji Sasaki🇯🇵 · Takaya Miyamoto🇯🇵 · Sinya Aoki🇯🇵 · Takumi Doi🇯🇵 · Tetsuo Hatsuda🇯🇵 · Yoichi Ikeda🇯🇵 · Takashi Inoue🇯🇵 · Noriyoshi Ishii🇯🇵

    The $\Delta \Delta$ dibaryon resonance $d^{\ast }(2380)$ with $(J^P,I)=(3^{+},0)$ is studied theoretically on the basis of the 3-flavor lattice QCD simulation with heavy pion masses ($m_{\pi }=679,841$ and $1018$ MeV). By using the HAL QCD method, the central $\Delta$-$\Delta$ potential in the ${}^7{S}_3$ channel is obtained from the lattice data with the lattice spacing $a\simeq 0.121$ fm and the lattice size $L\simeq 3.87$ fm. The resultant potential shows a strong short-range attraction, so that a quasi-bound state corresponding to $d^{\ast }(2380)$ is formed with the binding energy $25$-$40$ MeV below the $\Delta \Delta$ threshold for the heavy pion masses. The tensor part of the transition potential from $\Delta \Delta$ to $NN$ is also extracted to investigate the coupling strength between the $S$-wave $\Delta \Delta$ system with $J^P=3^{+}$ and the $D$-wave $NN$ system. Although the transition potential is strong at short distances, the decay width of $d^{\ast }(2380)$ to $NN$ in the $D$-wave is kinematically suppressed, which justifies our single-channel analysis at the range of the pion mass explored in this study.

    ↳ hep-lathep-exhep-phnucl-ex+1PLB(2020)·25 citations
41. 41*

    Bidirectional dynamic scaling in an isolated Bose gas far from equilibrium

    Jake A. P. Glidden🇬🇧 · Christoph Eigen🇬🇧 · Lena H. Dogra🇬🇧 · Timon A. Hilker🇬🇧 · Robert P. Smith🇺🇸 · Zoran Hadzibabic🇬🇧

    Understanding and classifying nonequilibrium many-body phenomena, analogous to the classification of equilibrium states of matter into universality classes, is an outstanding problem in physics. Any many-body system, from stellar matter to financial markets, can be out of equilibrium in a myriad of ways; since many are also difficult to experiment on, it is a major goal to establish universal principles that apply to different phenomena and physical systems. At the heart of the classification of equilibrium states is the universality seen in the self-similar spatial scaling of systems close to phase transitions. Recent theoretical work, and first experimental evidence, suggest that isolated many-body systems far from equilibrium generically exhibit dynamic (spatiotemporal) self-similar scaling, akin to turbulent cascades and the Family-Vicsek scaling in classical surface growth. Here we observe bidirectional dynamic scaling in an isolated quench-cooled atomic Bose gas; as the gas thermalises and undergoes Bose-Einstein condensation, it shows self-similar net flows of particles towards the infrared (smaller momenta) and energy towards the ultraviolet (smaller lengthscales). For both infrared (IR) and ultraviolet (UV) dynamics we find that the scaling exponents are independent of the strength of the interparticle interactions that drive the thermalisation.

    ↳ cond-mat.quant-gascond-mat.stat-mechhep-phphysics.atom-ph+1Nat.Phys.(2021)·102 citations
42. 42*

    QCD, Flavor, and the de Sitter Swampland

    John March-Russell🇬🇧 · Rudin Petrossian-Byrne🇬🇧

    The refined swampland de Sitter conjecture (SdSC) is a proposed constraint on the form of the total potential in a theory including quantum gravity. According to this conjecture potentials possessing metastable de Sitter vacua are in the swampland of effective field theories that cannot descend from a theory with gravity. It is known that in the Standard Model (SM), as the quark masses and theta-parameter are varied, IR- calculable metastable states in QCD appear (for N > 2 light quarks) and we discuss in detail their properties. We argue that the SdSC excludes the values of quark masses and theta for which these metastable states can arise, leading to a possible surprising connection between quantum gravity and aspects of low-energy flavor phenomenology. The observed values of the quark masses and QCD theta-parameter are consistent with the SdSC, giving mild indirect support for the conjecture. If, in addition, as partially indicated by large-N c and semi-classical analysis, pure SU (3) Yang-Mills theory has metastable states at theta = 0 (this to our knowledge is not known) then much of the a-priori SM parameter space is eliminated. In particular the limit of large electroweak vacuum expectation v_EW > 50 TeV is excluded by the SdSC if quark Yukawa couplings are kept fixed, possibly shedding a new light on the hierarchy problem. We argue that these statements are robust against the addition of a quintessence field unless extreme fine-tuning is allowed.

    ↳ hep-thhep-lathep-ph15 citations
43. 43*

    Potential of radio telescopes as high-frequency gravitational wave detectors

    Valerie Domcke🇩🇪 · Camilo Garcia-Cely🇩🇪

    In the presence of magnetic fields, gravitational waves are converted into photons and vice versa. We demonstrate that this conversion leads to a distortion of the cosmic microwave background (CMB), which can serve as a detector for MHz to GHz gravitational wave sources active before reionization. The measurements of the radio telescope EDGES can be cast as a bound on the gravitational wave amplitude, $h_c<10^{-21}(10^{-12})$ at 78 MHz, for the strongest (weakest) cosmic magnetic fields allowed by current astrophysical and cosmological constraints. Similarly, the results of ARCADE 2 imply $h_c<10^{-24}(10^{-14})$ at $3-30$ GHz. For the strongest magnetic fields, these constraints exceed current laboratory constraints by about seven orders of magnitude. Future advances in 21cm astronomy may conceivably push these bounds below the sensitivity of cosmological constraints on the total energy density of gravitational waves.

    ↳ astro-ph.COgr-qchep-phPRL(2021)·113 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.