Fri·Apr 3, 2020Friday·April 3, 2020

1. 01*

   VBSCan Mid-Term Scientific Meeting

   Julien Baglio🇨🇭 · Alessandro Ballestrero🇮🇹 · Riccardo Bellan🇮🇹 · Carsten Bittrich🇩🇪 · Simon Brass🇩🇪 · Ilaria Brivio🇩🇪 · Diogo Buarque Franzosi🇸🇪 · Claude Charlot🇫🇷 · Roberto Covarelli🇮🇹 · Javier Cuevas🇪🇸 · Michele Gallinaro🇵🇹 · Raquel Gomez-Ambrosio🇬🇧 and 39 other authors

   This document summarises the talks and discussions happened during the VBSCan Mid-Term Scientific Meeting workshop. The VBSCan COST action is dedicated to the coordinated study of vector boson scattering (VBS) from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

   hep-phhep-ex4 citations
2. 02*

   Radiative decay of ${\Xi }_b(6227)$ in a hadronic molecule picture

   HongQiang Zhu🇨🇳 · Yin Huang🇨🇳

   The ${\Xi }_b(6227)$ baryon with the quantum number $J^P=1/2^{-}$ is considered as a molecular state composed of a ${\Sigma }_b$ baryon and $\bar{K}$ meson. The partial decay widths of the ${\Sigma }_b\bar{K}$ molecular state into ${\Xi }_b\gamma$ and ${\Xi }_b^{{}^{\prime }}\gamma$ final states through hadronic loops are evaluated with the help of the effective Lagrangians. The partial widths for the ${\Xi }_b(6227)\to \gamma {\Xi }_b$ and ${\Xi }_b(6227)\to \gamma {\Xi }_b^{{}^{\prime }}$ are evaluated to be about 1.50-1.02 KeV and 17.56-24.91 KeV, respectively, which may be accessible for the LHCb. Based on our results we argue that an experimental determination of the radiative decay width of ${\Xi }_b(6227)$ is important for the understanding of its intrinsic properties.

   hep-phnucl-thCPC(2020)·12 citations
3. 03*

   Removing flat directions in SMEFT fits: how polarized electron-ion collider data can complement the LHC

   Radja Boughezal🇺🇸 · Frank Petriello🇺🇸 · Daniel Wiegand🇺🇸

   We study the potential of future Electron-Ion Collider (EIC) data to probe four-fermion operators in the Standard Model Effective Field Theory (SMEFT). The ability to perform measurements with both polarized electron and proton beams at the EIC provides a powerful tool that can disentangle the effects from different SMEFT operators. We compare the potential constraints from an EIC with those obtained from Drell-Yan data at the Large Hadron Collider. We show that EIC data plays an important complementary role since it probes combinations of Wilson coefficients not accessible through available Drell-Yan measurements.

   hep-phhep-exPRD(2020)·44 citations
4. 04*

   A model of electroweakly interacting non-abelian vector dark matter

   Tomohiro Abe🇯🇵 · Motoko Fujiwara🇯🇵 · Junji Hisano🇯🇵 · Kohei Matsushita🇯🇵

   We propose an electroweakly interacting spin-1 dark matter (DM) model. The electroweak gauge symmetry, SU(2)${}_L\times$U(1)${}_Y$, is extended into SU(2)${}_0\times$SU(2)${}_1\times$SU(2)${}_2\times$U(1)${}_Y$. A discrete symmetry exchanging SU(2)${}_0$ and SU(2)${}_2$ is imposed. This discrete symmetry stabilizes the DM candidate. The spin-1 DM particle ($V^0)$ and its SU(2)${}_L$ partners ($V^{\pm }$) interact with the Standard Model (SM) electroweak gauge bosons without any suppression factors. Consequently, pairs of DM particles efficiently annihilate into the SM particles in the early universe, and the measured value of the DM energy density is easily realized by the thermal freeze-out mechanism. The model also predicts a heavy vector triplet ($W^{\prime \pm }$ and $Z^{\prime }$) in the visible sector. They contribute to the DM annihilation processes. The mass ratio of $Z^{\prime }$ and $V^0$ determines values of various couplings, and constraints on $W^{\prime }$ and $Z^{\prime }$ restrict regions of the parameter space that are viable for DM physics. We investigate the constraints from perturbative unitarity of scalar and gauge couplings, the Higgs signal strength, $W^{\prime }$ search at the LHC, and DM direct detection experiments. It is found that the relic abundance of $V^0$ explains the right amount of the DM energy density for 3 TeV $\lesssim m_{V^0}\lesssim$ 19 TeV.

   hep-phJHEP(2020)·33 citations
5. 05*

   The production of the doubly charmed baryon in deeply inelastic $ep$ scattering at the Large Hadron Electron Collider

   Zhan Sun🇨🇳 · Xing-Gang Wu🇨🇳

   In this paper, we carry out a detailed study on the production of the doubly charmed baryon in deeply inelastic $ep$ scattering (DIS) for $Q^2\in [2,100]{\text{GeV}}^2$, at the Large Hadron Electron Collider (LHeC) with $E_e=60(140)$ GeV and $E_p=7000$ GeV. To exclude the contributions from the diffractive productions and the $b$ hadron decays, we impose the kinematic cuts $0.3<z<0.9$, and $p_{t,\text{baryon}}^{\star 2}>1{\text{GeV}}^2$ in the center-of-mass (CM) frame of ${\gamma }^{\ast }p$. Based on the designed LHeC luminosity, by detecting the decay channel ${\Xi }_{cc}^{+}({\Xi }_{cc}^{++})\to {\Lambda }_c^{+}$ with the subsequent decay ${\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+}$, we predict that about 1880 (2700) ${\Xi }_{cc}^{+}$ events and 3750 (5400) ${\Xi }_{cc}^{++}$ events can be accumulated per year, which signifies the prospect of observing them via the DIS at the forthcoming LHeC. In addition, we also predict the distributions of a rich variety of physical observables in the laboratory frame and the ${\gamma }^{\ast }p$ CM frame, including $Q^2$, $p_t^2$, $Y$(rapidity), $p_t^{\star 2}$, $Y^{\star }$, $W$, and $z$ distributions, respectively, which can provide helpful references for studying the doubly charmed baryon. In conclusion, we think that in addition to the LHC, the LHeC is also a helpful platform for studying the properties of the doubly charmed baryon.

   hep-phJHEP(2020)·18 citations
6. 06*

   Form factors for $B\to j_1{j}_2$ decays into two currents in QCD

   Mikhail A. Ivanov🇷🇺 · Dmitri Melikhov🇷🇺 · Silvano Simula🇮🇹

   We discuss the general properties of the $B$-meson decay form factors $F(q^2,q^{\prime 2})$, describing $B$-meson decays induced by two currents, e.g., $B$-decays into four leptons in the final state. We study the analytic properties of these complicated objects and identify those regions of $q^2$ and $q^{\prime 2}$, where perturbative QCD can be applied for obtaining predictions for the physical form factors.

   hep-phPRD(2020)·3 citations
7. 07*

   Fenomenología de modelos supersimétricos: partículas y materia oscura

   Andres D. Perez🇦🇷

   To elucidate the composition of dark matter (DM) is one of the most important open questions in particle and astroparticle phenomenology. Within the framework of minimal supersymmetric extensions of the standard model of fundamental particles, the `mu-from-nu supersymmetric standard model', $\mu \nu$SSM, solves the $\mu$-problem and reproduces neutrino data, only adding couplings involving right-handed neutrinos. In this context, the supersymmetric partner of the graviton, known as gravitino, becomes a natural DM candidate. Working in the mentioned model, in this thesis we have analyzed the detection of gamma-ray signals arising from decaying gravitino DM considering experiments such as $\text{Fermi}$-LAT. For this purpose all gravitino decays have been taken into account, complementing previous works. The possibility of an upcoming new generation of gamma-ray detectors has motivated the inclusion of axino, the supersymmetric partner of the axion, as a DM candidate. In this thesis, axino DM has been analyzed in the context of the $\mu \nu$SSM for the first time. Finally, scenarios with multicomponent DM have been studied, focusing on gravitinos and axinos coexisting as DM constituents. This novel scenario includes two very different cases with distinctive features: axino lighter than gravitino and vice versa. Considering the sensitivity of future MeV-GeV gamma-ray telescopes, axino and gravitino prospects of detection were analyzed in the mixed scenarios mentioned previously. In some parameter space regions, both candidates can produce a signal, therefore a double-line feature arises as a smoking gun that would uncover the DM composition.

   hep-phastro-ph.HEastro-ph.IM0 citations
8. 08*

   Renormalization of parton quasi-distributions beyond the leading order: spacelike vs. timelike

   V. M. Braun🇩🇪 · K. G. Chetyrkin🇩🇪 · B. A. Kniehl🇩🇪

   We argue that the renormalization factors for nonlocal quark-antiquark and gluon operators at space-like and time-like separations connected by a Wilson line coincide to all orders in perturbation theory. We calculate the anomalous dimensions and renormalization constants of quark-antiquark and gluon operators to three- and two-loop accuracy, respectively, and also compute vacuum expectation values of these operators to three-loop accuracy.

   hep-phhep-latJHEP(2020)·61 citations
9. 09*

   Boosting vector leptoquark searches with boosted tops

   Arvind Bhaskar🇮🇳 · Tanumoy Mandal🇮🇳 · Subhadip Mitra🇮🇳

   At the LHC, a TeV-scale leptoquark (LQ) that decays dominantly to a top quark ($t$) and a light charged lepton ($\ell =e,\mu$) would form a resonance system of \emph{boosted-$t$ $+$ high-$p_{\mathrm{T}}$-$\ell$}. We consider all possible vector LQ models within the Buchmüller-Rückl-Wyler classifications with the desired decay. We propose simple phenomenological Lagrangians that are suitable for bottom-up/experimental studies and, at the same time, can cover the relevant parameter spaces of these models. In this simplified framework, we study the pair and single production channels of vector LQs at the LHC. Interestingly, we find that, like the pair production, the cross sections of some single production processes also depend on the parameter $\kappa$ that appears in the gluon-vector LQ coupling. We adopt a search strategy of selecting events with at least one boosted hadronic top quark and exactly two high-$p_{\mathrm{T}}$ leptons of the same flavor and opposite sign. This combines events from the pair and single production processes and, therefore, can enhance the discovery potential beyond that of the pair-production-only searches. For $5\sigma$ discovery we find that vector LQs can be probed up to $2.55$ TeV for $100\%$ branching ratio in the $t\ell$ decay mode and $\mathcal{O}(1)$ new couplings at the $14$ TeV LHC with $3$ ab${}^{-1}$ of integrated luminosity.

   hep-phhep-exPRD(2020)·26 citations
10. 10*

    Production of heavy particle pairs via photon-photon processes at the LHC

    Marta Łuszczak🇵🇱 · Antoni Szczurek🇵🇱

    We discuss production of $W^{+}{W}^{-}$ pairs and $t\bar{t}$ quark-antiquark pairs in proton-proton collisions induced by two-photon fusion including transverse momenta of incoming photons. The unintegrated inelastic fluxes (related to proton dissociation) of photons are calculated based on modern parametrizations of deep inelastic structure functions in a broad range of $x$ and $Q^2$. We focus on processes with single and double proton dissociation. Highly excited remnant systems hadronise producing particles that can be vetoed in the calorimeter. We calculate associated gap survival factors. The gap survival factors depend on the process, mass of the remnant system and collision energy. The rapidity gap survival factor due to remnant fragmentation for double dissociative (DD) collisions is smaller than that for single dissociative (SD) process. We observe approximate factorisation: $S_{R,DD}\approx S_{R,SD}^2$ when imposing rapidity veto. For the $W^{+}{W}^{-}$ final state, the remnant fragmentation leads to a taming of the cross section when the rapidity gap requirement is imposed. Also for $t\bar{t}$ quark-antiquark pairs such a condition reverses the hierarchy observed for the case when such condition is taken into account. Our results imply that for the production of such heavy objects as $t$ quark and $\bar{t}$ antiquark the virtuality of the photons attached to the dissociative system are very large ($Q^2<$ 10${}^4$ GeV${}^2$). A similar effect is observed for the $W^{+}{W}^{-}$ system.

    hep-phActa Phys.Polon.B(2020)·0 citations
11. 11*

    QCD Phase Diagram at NICA energies: $K^{+}/{\pi }^{+}$ horn effect and light clusters in THESEUS

    D. Blaschke🇷🇺 · A.V. Friesen🇷🇺 · Yu.B. Ivanov🇷🇺 · Yu.L. Kalinovsky🇷🇺 · M. Kozhevnikova🇷🇺 · S. Liebing🇷🇺 · A. Radzhabov🇷🇺 · G. Röpke🇷🇺

    We discuss recent progress in the development of the three-fluid hydrodynamics-based program THESEUS towards an event generator suitable for applications to heavy-ion collisions at the intermediate energies of the planned NICA and FAIR experiments. We follow the strategy that modifications of particle distributions at the freeze-out surface in the QCD phase diagram may be mapped directly to the observable ones within a sudden freeze-out scheme. We report first results of these investigations for the production of light clusters (deuterons and tritons) which can be compared to experimental data from the HADES and the NA49 experiment and for the interpretation of the "horn" effect observed in the collision energy dependence of the $K^{+}/{\pi }^{+}$ ratio. Medium effects on light cluster production in the QCD phase diagram are negligible at the highest NICA energies but shall play a dominant role at the lowest energies. A sharp "horn"-type signal in the $K^{+}/{\pi }^{+}$ ratio can be obtained when the onset of Bose condensation modelled by a pion chemical potential results in an enhancement of pions at low momenta (which is seen at LHC energies) and would occur already in the NICA energy range.

    hep-phnucl-thActa Phys.Polon.Supp.(2021)·4 citations
12. 12*

    On the interplay between astrophysical and laboratory probes of MeV-scale axion-like particles

    Fatih Ertas🇩🇪 · Felix Kahlhoefer🇩🇪

    Studies of axion-like particles (ALPs) commonly focus on a single type of interaction, for example couplings only to photons. Most ALP models however predict correlations between different couplings, which change the phenomenology in important ways. For example, an MeV-scale ALP coupled to Standard Model gauge bosons at high energies will in general interact with photons, $W^{\pm }$ and $Z$ bosons as well as mesons and nucleons at low energies. We study the implications of such scenarios and point out that astrophysical constraints, in particular from SN1987A, may be substantially relaxed, opening up new regions of parameter space that may be explored with laboratory experiments such as NA62.

    hep-phastro-ph.COastro-ph.HEhep-exJHEP(2020)·80 citations
13. 13*

    Vector-Like Leptons and Inert Scalar Triplet: Lepton Flavor Violation, $g-2$ and Collider Searches

    A. S. de Jesus🇧🇷 · S. Kovalenko🇨🇱 · F. S. Queiroz🇧🇷 · K. Sinha🇺🇸 · C. Siqueira🇧🇷

    We investigate simplified models involving an inert scalar triplet and vector-like leptons that can account for the muon $g-2$ anomaly. These simplified scenarios are embedded in a model that features W' and Z' bosons, which are subject to stringent collider bounds. The constraints coming from the muon $g-2$ anomaly are put into perspective with collider bounds, as well as bounds coming from lepton flavor violation searches. The region of parameter space that explains the $g-2$ anomaly is shown to be within reach of lepton flavor violation probes and future colliders such as HL-LHC and HE-LHC.

    hep-phPRD(2020)·44 citations
14. 14*

    Holographic de Sitter Spacetime and Quantum Corrections to The Cosmological Constant

    Shuichi Yokoyama🇯🇵

    A dynamical aspect of quantum gravity on de Sitter spacetime is investigated by holography or the dS/CFT correspondence. We show that de Sitter spacetime emerges from a free Sp(N) vector model by complexifying the ghost fields and flowing them in parallel to the imaginary axis. We confirm that the emergence of de Sitter spacetime is ensured by conformal symmetry. We also compute the quantum corrections to the cosmological constant up to the next-to-leading order of the 1/N expansion in a proposed holographic approach. As a result the sub-leading corrections have the opposite sign to the classical value.This implies that a quantum gravity on de Sitter spacetime is perturbatively stable and quantum effects make the universe flatter and the cosmological constant smaller.

    ↳ hep-thgr-qchep-lathep-phPTEP(2020)·4 citations
15. 15*

    Gradient flow step-scaling function for SU(3) with ten fundamental flavors

    Anna Hasenfratz🇺🇸 · Claudio Rebbi🇺🇸 · Oliver Witzel🇺🇸

    We calculate the step scaling function, the lattice analog of the renormalization group $\beta$-function, for an SU(3) gauge theory with ten fundamental flavors. We present a detailed analysis including the study of systematic effects of our extensive data set generated with ten dynamical flavors using the Symanzik gauge action and three times stout smeared Möbius domain wall fermions. Using up to $32^4$ volumes, we calculate renormalized couplings for different gradient flow schemes and determine the step-scaling $\beta$ function for a scale change $s=2$ on up to five different lattice volume pairs. In an accompanying paper we discuss that gradient flow can promote lattice dislocations to instanton-like objects, introducing nonperturbative lattice artifacts to the step scaling function. Motivated by the observation that Wilson flow sufficiently suppresses these artifacts, we choose Wilson flow with the Symanzik operator as our preferred analysis. We study systematic effects by calculating the step-scaling function based on alternative flows (Zeuthen or Symanzik), alternative operators (Wilson plaquette, clover), and also explore the effects of the perturbative tree-level improvement. Further we investigate the effects due to the finite value of $L_s$.

    ↳ hep-lathep-phPRD(2020)·28 citations
16. 16*

    Dislocations under gradient flow and their effect on the renormalized coupling

    Anna Hasenfratz🇺🇸 · Oliver Witzel🇺🇸

    Non-zero topological charge is prohibited in the chiral limit of gauge-fermion systems because any instanton would create a zero mode of the Dirac operator. On the lattice, however, the geometric $Q_{\text{geom}}=⟨F\tilde{F}⟩/32{\pi }^2$ definition of the topological charge does not necessarily vanish even when the gauge fields are smoothed for example with gradient flow. Small vacuum fluctuations (dislocations) not seen by the fermions may be promoted to instanton-like objects by the gradient flow. We demonstrate that these artifacts of the flow cause the gradient flow renormalized gauge coupling to increase and run faster. In step-scaling studies such artifacts contribute a term which increases with volume. The usual $a/L\to 0$ continuum limit extrapolations can hence lead to incorrect results. In this paper we investigate these topological lattice artifacts in the SU(3) 10-flavor system with domain wall fermions and the 8-flavor system with staggered fermions. Both systems exhibit nonzero topological charge at the strong coupling, especially when using Symanzik gradient flow. We demonstrate how this artifact impacts the determination of the renormalized gauge coupling and the step-scaling $\beta$ function.

    ↳ hep-lathep-phPRD(2021)·10 citations
17. 17*

    Equation of state constraints from the threshold binary mass for prompt collapse of neutron star mergers

    Andreas Bauswein🇩🇪 · Sebastian Blacker🇩🇪 · Vimal Vijayan🇩🇪 · Nikolaos Stergioulas🇬🇷 · Katerina Chatziioannou🇺🇸 · James A. Clark🇺🇸 · Niels-Uwe F. Bastian🇵🇱 · David B. Blaschke🇷🇺 · Mateusz Cierniak🇵🇱 · Tobias Fischer🇵🇱

    Using hydrodynamical simulations for a large set of high-density matter equations of state (EoSs) we systematically determine the threshold mass M_thres for prompt black-hole formation in equal-mass and asymmetric neutron star (NS) mergers. We devise the so far most direct, general and accurate method to determine the unknown maximum mass of nonrotating NSs from merger observations revealing M_thres. Considering hybrid EoSs with hadron-quark phase transition, we identify a new, observable signature of quark matter in NS mergers. Furthermore, our findings have direct applications in gravitational wave searches, kilonova interpretations and multi-messenger constraints on NS properties.

    ↳ astro-ph.HEhep-phnucl-thPRL(2020)·144 citations
18. 18*

    Model-independent constraints in inflationary magnetogenesis

    Yuri Shtanov🇺🇦 · Mykhailo Pavliuk🇺🇦

    We derive a simple model-independent upper bound on the strength of magnetic fields obtained in inflationary and post-inflationary magnetogenesis taking into account the constraints imposed by the condition of weak coupling, back-reaction and Schwinger effect. This bound turns out to be rather low for cosmologically interesting spatial scales. Somewhat higher upper bound is obtained if one assumes that some unknown mechanism suppresses the Schwinger effect in the early universe. Incidentally, we correct our previous estimates for this case.

    ↳ astro-ph.COgr-qchep-phJCAP(2020)·23 citations
19. 19*

    Masses and Decay widths of Charmonium states in presence of strong magnetic fields

    Amruta Mishra🇮🇳 · S.P. Misra🇮🇳

    The masses and decay widths of charmonium states are studied in the presence of strong magnetic fields. The mixing between the pseudoscalar and vector charmonium states at rest is observed to lead to appreciable negative (positive) shifts in the masses of the pseudoscalar (longitudinal component of the vector) charmonium states in vacuum/hadronic medium in the presence of high magnetic fields. The pseudoscalar and vector charmonium masses in the hadronic medium, calculated in an effective chiral model from the medium changes of a scalar dilaton field, have additional significant modifications due to the mixing effects. The masses of the $D$ and $\bar{D}$ mesons in the magnetized hadronic matter are calculated within the chiral effective model. The partial decay widths of the vector charmonium state to $D\bar{D}$ are computed using a field theoretical model for composite hadrons with quark/antiquark constituents, and are compared to the decay widths calculated using an effective hadronic Lagrangian. The effects of the mixing are observed to lead to significant contributions to the masses of the pseusoscalar and vector charmonium states, and an appreciable increase in the decay width $\psi (3770)\to D\bar{D}$ at large values of the magnetic fields. These studies of the charmonium states in strong magnetic fields should have observable consequences on the dilepton spectra, as well as on the production of the open charm mesons and the charmonium states in ultra relativistic heavy ion collision experiments.

    ↳ nucl-thhep-phPRC(2020)·33 citations
20. 20*

    New estimator for symmetry plane correlations in anisotropic flow analyses

    Ante Bilandzic🇩🇪 · Marcel Lesch🇩🇪 · Seyed Farid Taghavi🇩🇪

    Correlations of symmetry planes are important observables used to quantify anisotropic flow phenomenon and constrain independently the properties of strongly interacting nuclear matter produced in the collisions of heavy ions at the highest energies. In this paper, we point out current problems of measuring correlations between symmetry planes and elaborate on why the available analysis techniques have a large systematic bias. To overcome this problem, we introduce a new approach to approximate multi-harmonic flow fluctuations via a two-dimensional Gaussian distribution. Employing this approximation, we introduce a new estimator, dubbed Gaussian Estimator (GE), to extract pure correlation between symmetry planes. We validate GE by using the realistic event-generator iEBE-VISHNU and demonstrate that it outperforms all existing estimators. Based on event-shape engineering, we propose an experimental procedure to improve GE accuracy even further.

    ↳ nucl-exhep-exhep-phnucl-thPRC(2020)·17 citations
21. 21*

    Independent measurement of Muon neutrino and anti-neutrino oscillations at the INO-ICAL Experiment

    Zubair Ahmad Dar🇮🇳 · Daljeet Kaur🇮🇳 · Sanjeev Kumar🇮🇳 · Md. Naimuddin🇮🇳

    The magnetised Iron Calorimeter detector at the India-based Neutrino Observatory (INO) has a unique feature to identify the neutrinos and antineutrinos on an event by event basis. This feature can be harnessed to detect the differences between the oscillation parameters of neutrinos and antineutrinos independently. In this paper, we analysed Charged Current ${\nu }_{\mu }$ and ${\overline{\nu }}_{\mu }$ events under the influence of earth matter effect using three neutrino flavor oscillation framework. If the atmospheric mass-squared differences and mixing parameters for neutrinos are different from antineutrinos, we present the prospects for the experimental observation of these differences in atmospheric $\nu$ and ${\overline{\nu }}_{\mu }$ oscillations at INO. We estimate the detector sensitivity to confirm a non-zero difference in the mass-squared splittings ($|\Delta m_{32}^2|-|\Delta {\overline{m^2}}_{32}|$) for neutrinos and antineutrinos.

    ↳ hep-exhep-phJ.Phys.G(2019)·6 citations
22. 22*

    Vortices and waves in light dark matter

    Lam Hui🇺🇸 · Austin Joyce🇺🇸 · Michael J. Landry🇺🇸 · Xinyu Li🇺🇸

    In a galactic halo like the Milky Way, bosonic dark matter particles lighter than about $30$ eV have a de Broglie wavelength larger than the average inter-particle separation and are therefore well described as a set of classical waves. This applies to, for instance, the QCD axion as well as to lighter axion-like particles such as fuzzy dark matter. We show that the interference of waves inside a halo inevitably leads to vortices, locations where chance destructive interference takes the density to zero. The phase of the wavefunction has non-trivial winding around these points. This can be interpreted as a non-zero velocity circulation, so that vortices are sites where the fluid velocity has a non-vanishing curl. Using analytic arguments and numerical simulations, we study the properties of vortices and show they have a number of universal features: (1) In three spatial dimensions, the generic defects take the form of vortex rings. (2) On average there is about one vortex ring per de Broglie volume and (3) generically only single winding ($\pm 1$) vortices are found in a realistic halo. (4) The density near a vortex scales as $r^2$ while the velocity goes as $1/r$, where $r$ is the distance to vortex. (5) A vortex segment moves at a velocity inversely proportional to its curvature scale so that smaller vortex rings move faster, allowing momentary motion exceeding escape velocity. We discuss observational/experimental signatures from vortices and, more broadly, wave interference. In the ultra-light regime, gravitational lensing by interference substructures leads to flux anomalies of $5-10\%$ in strongly lensed systems. For QCD axions, vortices lead to a diminished signal in some detection experiments but not in others. We advocate the measurement of correlation functions by axion detection experiments as a way to probe and capitalize on the expected interference substructures.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph+1JCAP(2021)·84 citations
23. 23*

    Vacuum arbitrariness and the Hubble tension

    Ali Kaya🇺🇸

    We show that the energy density of the superhorizon modes released in a non-Bunch-Davies vacuum can be arbitrarily large during inflation and it decreases like ln(a)/a^4 in the subsequent radiation dominated era. This may constitute a dark radiation component which can sufficiently alter the early cosmological evolution to alleviate the Hubble tension.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2020)·1 citation

* 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.