High Energy Physics (Theory)
Holography in the linearized quantum gravity regime and modular crossed product
Avinandan Mondal
Within the semi-classical regime of AdS/CFT correspondence, we consider the limit where the bulk dynamical field is linearized metric perturbations satisfying linearized Einstein equations over background pure AdS spacetime. AdS/CFT correspondence gives us a
holographic map, which is an isometric
embedding map of the GNS
Hilbert space of linearized
gravity in the bulk (w.r.t. the AdS-invariant
vacuum) to the GNS
Hilbert space of CFT in the boundary (w.r.t. the Minkowski-invariant
vacuum). We assume that the map takes AdS-
vacuum in the bulk to CFT-
vacuum in the boundary and that it allows AdS-Rindler wedge reconstruction. Then using this map, we show that for a given ball-shaped region in the boundary $A$, the relative
entropy of a bulk state w.r.t. the AdS
vacuum in the
algebra of causal wedge associated to $A$ matches with the relative
entropy of the dual CFT state w.r.t. the CFT
vacuum in the
algebra of CFT observables in $A$ in the code subspace, which is known as Jafferis-Lewkowycz-Maldacena-Suh (JLMS) condition. Furthermore, for localized semi-classical coherent excitations in the causal wedge associated to $A$ which corresponds to perturbed bulk geometry, we show rigorously using modular crossed product construction that the state-dependent part of
entropy of the dual CFT state in the dressed Type-II
algebra associated to $A$ satisfies
vacuum subtracted Hubeney-Rangamani-Takayanagi (HRT) formula.
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High Energy Astrophysical Phenomena
Exploring cosmic magnetism with gamma-ray burst afterglow emission
Paolo Da Vela, Davide Miceli, Lara Nava et al. (+1 more)
The nature and origin of
magnetic fields on cosmological scales are still unclear.
Magnetic fields detected in
galaxies and
galaxy clusters are typically interpreted as the result of the amplification of weak seed fields, but their nature remains largely unknown with two scenarios considered: the cosmological and the astrophysical origin. Signatures of magnetization in
cosmic voids from observations of very high energy (VHE, E > 100 GeV)
photons from extragalactic sources can provide crucial results. Indeed, if a non-negligible intergalactic
magnetic field (IGMF) is present in the voids, a time-delayed emission known as pair-echo is expected. The timing and intensity of this signal encode information on the IGMF strength B and properties. Given the recent detection of gamma-ray burst (GRB) afterglows at TeV energies, for this study we performed a detectability study of pair-echo signatures from GRBs. We simulated afterglow emission for different values of the jet kinetic energy (E$_{k,iso}$ = 10$^{49}$ - 10$^{55}$ erg),
redshift (z = 0.03 - 1), and lightcurve break times, and estimated the expected pair-echo radiation for IGMF strengths in the range B = 10$^{-19}$ - 10$^{-16}$ G. We investigated the capability of CTAO to detect the resulting emission at tens of GeV. We find that a subsample of GRBs in the z - E$_{k,iso}$ parameter space can produce a detectable pair-echo component for CTAO for all the tested IGMF strengths. A steepening of the GRB afterglow light curve, caused e.g. by an early (0.1 - 1 days) jet break, is a key factor to increase the chances of detection. CTAO observations starting from 10 - 12 h after the GRB trigger and extending up to a few days can provide valuable information on the IGMF.
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All authors Paolo Da Vela, Davide Miceli, Lara Nava, Giancarlo Ghirlanda
Materials Science
Parity-selective spin splitting in coplanar antiferromagnets via bichromatic driving
Di Zhu, Zhongbo Yan and Mohsen Yarmohammadi
Parity is a central characteristic of momentum-dependent
spin splitting in antiferromagnets (AFMs). Yet, intrinsic
crystal symmetries typically restrict the splitting to either even or odd parity, preventing flexible
spin control. Using a coplanar AFM, we demonstrate that bichromatic ($\omega$–$n\omega$) Floquet driving offers a natural way to bypass this constraint. This mechanism generates asymmetric
spin textures unattainable in static AFMs or under monochromatic driving. For the specific AFM considered here, we reveal an elegant relation between
spin-splitting parity and harmonic hierarchy: $\omega$–$2\omega$ fields generate highly tunable odd- and mixed-parity
spin splittings, whereas higher-order harmonics ($n \ge 3$) exclusively produce even-parity states. The macroscopic magnetization can also be toggled via the specific driving protocol and harmonic $n$. These distinct
spin splitting states manifest in qualitatively different macroscopic
spin currents generated after an optical quench—a definitive transport signature complementing direct visualization via
spin- and angle-resolved photoemission spectroscopy.
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High Energy Physics (Phenomenology)
Precise predictions for double Higgs production in association with a vector boson in Effective Field Theory
Ramona Gröber, Michał Ryczkowski and Gioia Sacchi
We present next-to-next-to-leading order (NNLO) QCD predictions for
Higgs boson pair production in association with a weak gauge
boson, $pp \to Vhh$ with $V=W^\pm,Z$, in effective field theory descriptions of new physics. We consider both the Standard Model Effective Field Theory (SMEFT), truncated at dimension six, and the
Higgs Effective Field Theory (HEFT) at leading order in the
chiral expansion. The calculation builds on the factorisation of the
quark-induced production process into Drell-Yan production of an off-shell vector
boson and its subsequent decay into $Vhh$, supplemented in the $Zhh$ channel by the loop-induced $gg \to Zhh$ contribution that first enters at NNLO QCD. We provide inclusive predictions at $\sqrt{s}=13.6$ and $14.0$ TeV, including scale, PDF, and $\alpha_s$ uncertainties, and express the results in terms of numerical coefficients that allow fast evaluations for arbitrary EFT parameters in the considered ranges. We find that, for $W^\pm hh$ production, QCD corrections largely factorise from the EFT dependence, leading to almost flat $K$-factors. In contrast, $Zhh$ production shows a stronger dependence on the EFT coefficients because of the
gluon-induced component.
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High Energy Astrophysical Phenomena
Relativistic effects of PSR~J1856–0039 double neutron star system in a 2.36-hour compact orbit
Z. L. Yang, J. L. Han, W. Q. Su et al. (+11 more)
Compact double
neutron star (DNS) systems are unique laboratories for testing gravitational theories and studying DNS mergers. Here we report the properties of a new DNS system, PSR J1856–0039, discovered in the Five-hundred-meter Aperture Spherical
radio Telescope (FAST). The
pulsar is mildly recycled with a period of 23.4~ms in a compact eccentric orbit ($e=0.106$) with an orbital period of 2.36 hours. By following up FAST observations, we measured the relativistic effects, including the orbital period derivative $\dot{P}_{\rm orb}=-1.284\pm0.019\times10^{-12}$ s s$^{-1}$, periastron advance $\dot\omega=17.5859\pm0.0007$ deg yr$^{-1}$, and Einstein delay $\gamma=0.445\pm0.011$ ms. This DNS system has a low orbital inclination of $i=133^\circ.2\pm1^\circ.1$ and the lowest total mass of any known DNS, $M_{\rm tot}=2.48841\pm0.00015 M\odot$, with a determined
pulsar mass of $1.304\pm0.022 M_\odot$ and a companion mass of $1.185\pm0.022 M_\odot$, one of the lowest
neutron-
star masses. The observed orbital decay due to gravitational-wave emission $\dot{P}^{\rm GW}_{\rm orb,obs}$ and the orbital decay predicted by general relativity $\dot{P}^{\rm GW}_{\rm orb,pred}$ are consistent at a level of $\dot{P}^{\rm GW}_{\rm orb,obs}/\dot{P}^{\rm GW}_{\rm orb,pred}=$1.009(14) (68% confidence). This DNS will merge after 82 Myr and may form a stable
neutron star or collapse into a black hole after
spin-down. Long-term monitoring could potentially probe the Lense-Thirring precession.
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All authors Z. L. Yang, J. L. Han, W. Q. Su, P. F. Wang, C. Wang, T. Wang, D. J. Zhou, Yi Yan, J. Xu, W. C. Jing, N. N. Cai, R. X. Xu, H. G. Wang, X. P. You
Instrumentation and Methods for Astrophysics
Commissioning and on-sky performance verification of iLocater
Marshall C. Johnson, Marcelo Tala Pinto, Jonathan Crass et al. (+59 more)
iLocater is a high-resolution near-infrared extreme precision radial velocity (EPRV) spectrograph that was deployed to the Large Binocular
Telescope (LBT) in June 2026. iLocater operates over $\lambda=966-1312$ nm with a median resolving power of $R=205,000$ as measured in the laboratory. We present the commissioning and initial on-sky verification program using
solar and night-time observations at the LBT. First light was achieved on 27 June 2026, and nearly 150 on-sky spectra have now been recorded. Observations include single
stars ranging in spectral type from B5 to M6. iLocater uses the LBT AO system, and we have demonstrated its ability to obtain spatially resolved spectra of close ($\theta < 1''$) binary
stars.
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All authors Marshall C. Johnson, Marcelo Tala Pinto, Jonathan Crass, Brian Sands, Jackson Datkuliak, Sai Vidyud Senthil Nathan, Justin R. Crepp, Michael Engelman, Daniel Pappalardo, Julia Brady, Mark Derwent, Xavier Lesley-Saldaña, Andrew Bechter, Eric Bechter, Christian Schwab, David Aikens, Chad Bender, Chris Brandon, Cynthia Brooks, Matheus J. Castro, Jeffrey Chilcote, Al Conrad, Gregory Delo, Erin Duell, Matthew Engstrom, Steve Ertel, Louis Fantano, John Keith Feggans, Hali Flores, B. Scott Gaudi, David King, Ondrej Kitzler, Kaitlin M. Kratter, Jeffrey Kruk, Thomas Legero, Stanimir Letchev, Jerry Mason, Joaquin Mason, Matthew Misch, Jacob Pember, Richard Pogge, Andreas Quirrenbach, Joshua Schlieder, Augustyn Waczynski, Joseph Shields, Daewook Kim, Mark Smithwright, Allie Renshaw, Austin Richie, Alexa Rizika, Nandini Sadagopan, Jonathan Shover, James Smous, Jayde Spiegel, Julian Stürmer, Sahil Sura, Robert Switzer, Joe Thomes, Ji Wang, Lauren Weiss, Daniel Wilson, Dane Zielinski-Nicolson
Strongly Correlated Electrons
Altermagnetism from a Cu-Fe Lieb Lattice in FeSe/Cuprate Heterostructures
Ying Li, Augustin Davignon, Peng Rao et al. (+4 more)
Realizing altermagnetism in high-$T_c$ cuprate-based systems would provide a direct route for studying
spin-split electronic bands in the absence of net magnetization and investigate their interplay with unconventional superconductivity. Here, we propose that FeSe/cuprate
heterostructures offer such a platform, where a 45$^\circ$ twist of Cu and Fe layers creates an effective CuFe$_2$ Lieb
lattice in which Fe
magnetic order and Cu-Fe hybridization through the ligands induces altermagnetic $d$-wave
spin splitting. A minimal tight-binding model shows that this mechanism is generic. Furthermore, a substrate-induced inequivalence of the two Se sites in FeSe provides a second route in which altermagnetism originates in the Fe layer and is transferred to the cuprate layer by proximity. Density functional theory calculations for FeSe/Bi$_2$Sr$_2$CuO$_6$
heterostructures confirm the viability of both mechanisms and reveal ways to enhance the
spin splitting. These results establish superconducting cuprate/transition metal chalcogenide
heterostructures as a promising setting for engineering altermagnetism and studying its coupling to unconventional superconductivity.
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All authors Ying Li, Augustin Davignon, Peng Rao, Runhan Li, Maia G. Vergniory, Roser Valentí, Johannes Knolle
Instrumentation and Methods for Astrophysics
The Calibration System of the iLocater Spectrograph
Sai Vidyud Senthil Nathan, Jonathan Crass, Julia E. Brady et al. (+21 more)
iLocater is a new near-infrared, extreme precision radial velocity (EPRV) instrument delivered to the Large Binocular
Telescope in the summer of 2026. The instrument utilizes single-mode fibers (SMFs) for light transmission, including its calibration systems. We present an overview of the iLocater calibration system, detailing the specific sources and the hardware required to inject calibration light into the SMFs. Furthermore, we discuss the hardware that efficiently switches between these sources and distributes the light to all necessary instrument locations, entirely eliminating the need for free-space propagation.
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All authors Sai Vidyud Senthil Nathan, Jonathan Crass, Julia E. Brady, Mark Derwent, Marcelo Tala Pinto, Brian Sands, Jackson Datkuliak, Jonathan Shover, Christian Schwab, Julian Stürmer, Stanimir O. Letchev, Jacob Pember, Jayde Spiegel, Erin Duell, Daniel Pappalardo, Marshall C. Johnson, Michael Engelman, Matheus J. Castro, Justin R. Crepp, Ondrej Kitzler, Thomas Legero, Xavier Lesley-Saldaña, Richard Pogge, Dane Zielinski-Nicolson
Astrophysics of Galaxies
An Exploratory Analysis of New Large Gaia-informed Quasar Samples in SDSS-V
Shir Aviram, Benny Trakhtenbrot, Tom Dwelly et al. (+22 more)
Quasars are luminous objects that provide insights into the physics and
evolution of supermassive black holes (SMBHs) and their
accretion flows,
galaxy evolution, and even cosmology. In this study, we present an exploratory study based on the ongoing fifth generation of the Sloan Digital Sky Survey (SDSS-V) and its unique dual-hemisphere, wide-field, and multi-object spectroscopic capabilities, with the aim of creating a comprehensive, all-sky
quasar sample. The targets were selected through two novel methods, GUA and Skewt-QSO, that rely primarily on data from WISE and
Gaia, aiming to address gaps in previous large
quasar samples. Our sample includes over 250,000 spectroscopically confirmed
quasars reaching z~5, with tens of thousands of newly identified
quasars in the southern hemisphere. The selection methods are highly pure, with well over 80% of the spectra collected being genuine
quasars; the main contaminants are M-type
stars. The detailed spectral decomposition procedure we employed shows that the
quasars in the sample span a wide range of luminosities (Lbol~$10^{44}-10^{48} erg s^{-1}$), SMBH masses (MBH~$10^6-10^{10}$ Msun), and
accretion rates (L/LEdd~0.01-1). The distributions of these properties are consistent with those of previous
quasar catalogs, which are based on past generations of SDSS, once we account for potential selection biases related to the various survey depths. Our findings confirm that novel selection methods based on optical+IR colors and/or astrometry can yield a large, high-purity
quasar sample over wide sky areas, including in cases where more nuanced multi-band photometry and/or multi-wavelength data in the X-ray or
radio is not available. This SDSS-V sample, which will continue to grow, establishes a robust reference for future southern (time-domain) surveys, while enhancing and complementing our understanding of
quasar demographics and SMBH
evolution.
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All authors Shir Aviram, Benny Trakhtenbrot, Tom Dwelly, Scott F. Anderson, Sean Morrison, Michael Eracleous, Yue Shen, Mara Salvato, Donald P. Schneider, Roberto J. Assef, Catarina Aydar, Franz E. Bauer, W.N. Brandt, Joel R. Brownstein, Johannes Buchner, Jeremy Darling, Jose G. Fernandez-Trincado, Patrick B. Hall, Dong-Woo Kim, Anton M. Koekemoer, Stephanie LaMassa, Andrea Merloni, Claudio Ricci, Qian Yang, Grisha Zeltyn
Solar and Stellar Astrophysics
PANTERA. I. Hunting for the Most Metal-Rich Stars in the Solar Neighborhood with High-Resolution Spectroscopy
Serat M. Saad, D. M. Rowan, K. Z. Stanek et al. (+4 more)
We present PANTERA (Project for Astrophysical Nucleosynthesis and Targeted Exploration of metal-Rich Abundances), a high-resolution spectroscopic survey of the most metal-rich
stars in the
solar neighborhood. In this first paper, we report iron abundances for 56 metal-rich
stars, selected from
Gaia DR3 XP spectrophotometric
metallicities. These targets were observed with the PEPSI spectrograph on the Large Binocular
Telescope (LBT), the Levy spectrograph on the Automated
Planet Finder (APF)
telescope, and the HIRES spectrograph on the Keck
telescope. We measure [Fe/H] from an equivalent-width analysis of iron lines, with the effective temperature taken from photometry and the surface
gravity from the
Gaia parallax. We verify our measurement using
Gaia benchmark stars, observing some sources with more than one spectrograph, using a second synthesis code, and an independent equivalent-width measurement. We find that the
Gaia-XP
metallicities over-predict [Fe/H] for part of our sample: they are consistent for the
dwarfs, though a selection bias limits what the
dwarf agreement can show, and reach $0.16\pm0.02$ dex for the cool
giants. We attribute the over-prediction in part to the strong blue line blanketing of the cool metal-rich
giants and to the survey labels on which the XP
metallicities were trained. We also found 25 of the 56
stars to be ultra-metal-rich ([Fe/H] $> 0.4$), with the most iron-rich
stars reaching [Fe/H]$=+0.58$. We discuss the implications of our result on studying metal-rich populations.
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All authors Serat M. Saad, D. M. Rowan, K. Z. Stanek, Ilya Ilyin, Benjamin J. Fulton, Howard Isaacson, Jessica Lu
High Energy Physics (Theory)
On quantum corrections to semiclassical strings on $\mathrm{AdS}_5\times S^5/\mathbb{Z}_{L}$ orbifold backgrounds
Carlos Barredo Martínez
We consider three families of semiclassical string solutions on AdS$_5\times S^5/\mathbb{Z}_L$ orbifold backgrounds which correspond to `twisted' single-trace operators in the SU$(2)$, SU$(3)$ and SL$(2)$ sectors, respectively, of the dual 4d $\mathcal{N}=2$ quiver gauge theory. The leading
quantum correction to the classical energy of each solution is computed, and is matched, despite the lack of maximal supersymmetry, to the corresponding results from finite-size corrections to the twisted Bethe ansatz in the continuum $J\to\infty$ limit and the associated Landau-Lifshitz low-energy effective theory. The $\mathbb{Z}_L$ quotient allows the string to have fractional winding branches $\mu=\widetilde{m}+\frac{n}{L}$ along orbifolded directions. As such, stability is a property of the full winding branch $\mu$, rather than of the individual twisted sectors $n$. Restricting to the purely fractional branch ($\widetilde m=0$), we obtain new stable configurations which were absent in the analogous semiclassical string solutions on AdS$_5\times S^5$. The energies of these stable states connect smoothly to those of states in relevant BPS sectors as $\mu\to0$.
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High Energy Astrophysical Phenomena
Semi-analytic Inference of Satellite Densities in the Cold Dark Matter Model Part II. Implications for Dark Matter Indirect Detection Constraints
Kailash Raman, Dylan Folsom, Manoj Kaplinghat et al. (+2 more)
Dwarf galaxies provide excellent targets to search for signals of dark matter annihilation or decay. Using a calibrated semi-analytic model and the latest
stellar kinematic data (presented in Part I), this paper updates the astrophysical J-factors for the Milky Way's
dwarf spheroidal
galaxies. We infer the probability distributions for the J-factors of 39
dwarfs by conditioning a population of subhalos, generated with the SatGen semi-analytic satellite model, on either a
dwarf's kinematically determined dynamical mass or its
stellar mass. We also compute the J-factors using the Jeans equation with updated
stellar kinematics and priors that incorporate varying degrees of SatGen information. We use the computed J-factors to recast existing limits from
Fermi-LAT data on the annihilation cross section. Our main result is that variations in the J-factors computed using the Jeans analysis introduce a factor of 2-4 uncertainty into the inferred limits on the cross section. We argue that a cosmologically informed prior is a motivated choice that excludes thermal relic annihilation cross sections to $b\bar{b}$ below about 70 GeV. For comparison, the more commonly used priors, which can lead to unphysical
halo parameters, exclude masses below 130 GeV at 95% confidence level. We also show that the highest-J-factor
dwarfs are spatially extended, approximately one degree on the sky, which challenges the validity of the point-source approximation adopted in many analyses of
Fermi data. Finally, based on the semi-analytic model and the kinematic data, the highest J-factor
halos have already been discovered, suggesting future ultra-faint discoveries are unlikely to substantially strengthen limits on annihilating dark matter.
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All authors Kailash Raman, Dylan Folsom, Manoj Kaplinghat, Mariangela Lisanti, Benjamin R. Safdi
High Energy Physics (Phenomenology)
Seesaw Cosmology
Nicolás Bernal, Chee Sheng Fong and Óscar Zapata
We study perturbative reheating in which the inflaton transfers its energy to the Standard Model through right-handed
neutrinos (RHNs) responsible for light-
neutrino masses via the type-I seesaw mechanism. We refer to the resulting nonstandard thermal history as $seesaw$ $cosmology$. When produced relativistically and sufficiently long lived, the RHNs generate a characteristic sequence of inflaton, relativistic-RHN, nonrelativistic-RHN, and Standard Model radiation domination. We solve the Boltzmann system while retaining the production-time dependence of the nonthermal RHN distribution and its relativistic-to-nonrelativistic transition. The Standard Model temperature rapidly approaches a plateau during inflaton domination and subsequently scales as $a^{-1/4}$ and $a^{-3/8}$ during relativistic- and nonrelativistic-RHN domination, respectively. We investigate the implications of seesaw cosmology for dark-matter production. Direct production through inflaton decays can be enhanced relative to conventional reheating by a factor of order $m_\phi/(2m_N)$, while ultraviolet freeze-in exhibits the critical temperature powers $p = 12$ and $20$, leading to potentially large contributions before the final radiation-dominated era. Seesaw cosmology therefore connects
neutrino-mass generation, the pre-BBN thermal history and phenomena such as dark-matter production and baryogenesis.
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Solar and Stellar Astrophysics
The T-GEX project. I. Stealth UV-bright Sun-like stars in the Galaxy as candidate contributors to the UV upturn
M. L. L. Dantas, D. Beltrán, R. E. Giribaldi et al. (+3 more)
We constructed the Tiny
Gaia-ESO + GALEX (T-GEX) catalogue by combining
Gaia-ESO spectroscopy,
Gaia DR3 astrometry, GALEX UV photometry, and 2MASS and AllWISE infrared measurements for 37
stars. Astrometric and spectroscopic quality cuts minimise obvious multiplicity and spectral peculiarity, although unresolved companions cannot be excluded. We classified the
stars relative to the empirical FGK UV-normal locus, applied a 3-component Gaussian mixture model in the FUV-NUV versus NUV-$G$ plane, measured H$\alpha$ $\lambda 6563$ diagnostics for 24
stars, and performed an IMF-based empirical scaling calculation for three UV-upturn
galaxies. Approximately 2/3 of the sample are UV-abnormal. The GMM identifies a cool, strongly UV-excess group (G1), a hotter UV-normal group (G2), and an intermediate UV-excess group (G3). G1 occupies a narrow, predominantly sub-
solar [Fe/H] range and is $\alpha$-enhanced, with the highest median [Mg/Fe]. G3 has the highest median [Fe/H], while G2 spans the broadest
metallicity range and has the youngest median age. G1 and G3 extend to old ages, although their youngest estimates are affected by isochrone degeneracy. Enhanced H$\alpha$ core emission occurs only among hotter G2
stars in the available subsample, but only one G1
star has H$\alpha$ coverage. The extragalactic contribution is strongly template-dependent: the median G1 template accounts for at most $\sim20\%$ of the observed UV output, whereas the bluest template could match most or all of the NUV and FUV emission if shared by $\sim10$–$15\%$ of surviving FGK
stars.
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All authors M. L. L. Dantas, D. Beltrán, R. E. Giribaldi, R. Smiljanic, P. R. T. Coelho, P. B. Tissera
High Energy Physics (Phenomenology)
The inseparable three and four tops
Gauthier Durieux, Hesham El Faham, Rikkert Frederix et al. (+2 more)
In measurements of four-top-
quark production ($tttt$), LHC collaborations observe a significant degeneracy with three-top-
quark production. We compute the dominant three-top-production mode, namely associated production with a $W$
boson ($tttW$), at complete next-to-leading order (NLO), including all possible QCD and electroweak (EW) corrections. Beyond leading order (LO), $tttW$ production with the radiation of an additional $b$-flavoured
quark contributes to the same final state as $tttt$ production with a $t \to bW$ decay. Away from the on-shell top-
quark limit, the usual overlap removal of resonant contributions in the non-resonant computation either breaks gauge invariance and generates unitarity violation or involves a significant arbitrariness in the required reshuffling of momenta. To overcome these issues, we introduce a novel window-removal prescription that produces consistent predictions for the inseparable $tttW+tttt$ process, with both components described at NLO accuracy. We argue that such a joint prediction should be used in comparisons with experimental selections targeting $tttt$ production, since the on-shell $tttt$ component can not be isolated in practice. Such a joint prediction has an inclusive rate more than 10% higher than the purely on-shell $tttt$ one. We also study an idealised veto on additional hard and central $b$-jet radiation, which suppresses the contributions of resonant $tttt$ diagrams as well as their interference with non-resonant $tttW$ ones and therefore defines a relatively pure $tttW$-like signal region. Formally subleading coupling orders are numerically important at LO, while the corresponding subleading NLO corrections largely cancel both inclusively and differentially. Consequently, the complete-NLO prediction is well approximated by retaining the first three LO coupling orders together with the leading QCD NLO correction.
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All authors Gauthier Durieux, Hesham El Faham, Rikkert Frederix, Davide Pagani, Marco Zaro
High Energy Physics (Theory)
geoSCET: Soft Theorems from Power Counting
Timothy Cohen, Patrick Hager and Andreas Helset
We apply the framework of Soft Collinear Effective Theory (SCET) to the theory of the
geometric scalar field. The resulting “geoSCET” manifests an emergent geometry in the soft sector, mirroring the emergent soft gauge invariance of QCD SCET. We use geoSCET to derive the
geometric soft
theorems as straightforward consequences of effective-field-theory power counting, including extensions to multiple soft emissions and loop corrections. We demonstrate that theories without a potential satisfy universal
geometric soft
theorems for any number of soft emissions to all orders in perturbation theory. We also show that we can turn on a potential at the soft scale without spoiling the factorization of the soft physics. This work demonstrates the underlying field-space diffeomorphism origin of the
geometric soft
theorem.
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Strongly Correlated Electrons
Spin-incoherent Mott-Thouless pumps
Ajesh Kumar, Urban F. P. Seifert, Erez Berg et al. (+1 more)
A Thouless pump describes a system in which a quantized amount of charge is transported by one
lattice spacing per cycle when the parameters of a
Hamiltonian are varied slowly and periodically. In the standard case, this quantization requires the system to remain in its ground state with vanishing thermodynamic
entropy throughout the pumping process. Here, we introduce a class of Mott-Thouless pumps, which operate in highly entropic,
spin-incoherent Mott states. We show analytically that these states exhibit exponentially protected quantized transport despite their extensive
entropy, because the pumped charge resides in a gapped sector that remains dynamically decoupled from the hot
spin degrees of freedom. By contrast, motivated by a recent experimental realization, we identify other classes of Mott-Thouless pumps that lack this protection. In these systems,
spin excitations can efficiently generate charge excitations, leading to a rapid breakdown of quantized transport. Our analytical results are supported by numerically exact real-time simulations of finite systems.
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All authors Ajesh Kumar, Urban F. P. Seifert, Erez Berg, Achim Rosch
Instrumentation and Methods for Astrophysics
Emulating Cosmic Structure Formation with a Lagrangian Neural Cellular Automaton
Cooper Jacobus, Beatriz Tucci and Oliver Philcox
Field-level inference of cosmological initial conditions from
galaxy surveys requires a forward model that is simultaneously accurate in the non-linear regime, computationally efficient, and fully differentiable. Traditional N-body simulations are accurate but computationally prohibitive for iterative inference, while approximate solvers like Lagrangian Perturbation Theory (LPT) fail to capture the knotty
halo-forming dynamics of the
cosmic web at late times. We introduce the Lagrangian Neural Cellular Automaton (LNCA), a hybrid deep learning framework that can be applied to emulate structure formation as a local, iterative dynamical process on a comoving
lattice. Unlike convolutional emulators which map fixed grids in a single pass, the LNCA operates in the Lagrangian frame, iteratively advecting the computational graph itself to follow the flow of mass. By training the network to learn only the residual displacement corrections to the Zeldovich approximation, we achieve high-fidelity emulation of the non-linear physics while guaranteeing accuracy at large scales. We further constrain our model to produce complete trajectories, not just final states, by adopting an equivariant cellular automaton architecture, which recurrently iterates on its internal states to yield a dynamic history. The resulting update rule acts on a single fixed neighborhood, is translationally and rotationally equivariant, and is integrated over discrete substeps to yield trajectories, making it a differentiable forward model for reconstructing the initial conditions of the universe from lightcone data. We train our model to emulate the real-space matter distributions of a diverse set of N-body simulations from the Quijote suite, for a range of
redshifts and cosmologies, given only the initial conditions.
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Astrophysics of Galaxies
The influence of feedback on the baryonic content of haloes in the COLIBRE simulations
Jonathan J. Davies, Joop Schaye, Filip Huško et al. (+7 more)
We present predictions for the relation between the
halo gas mass fraction and
halo mass, $f_{\rm gas}^{200}-M_{200}$, from the COLIBRE cosmological simulations of
galaxy formation, and explore how the gas content of
haloes is influenced by feedback from
supernovae and active
galactic nuclei (AGN) over time. The $f_{\rm gas}^{200}-M_{200}$ relation in COLIBRE is non-monotonic, with a peak at $M_{200}\sim 10^{11.5-12}$~M$_\odot$. Below this mass, feedback from
supernovae efficiently expels gas from the
haloes of
dwarf galaxies, and above it, AGN feedback efficiently depletes the
haloes of
galaxy groups. The fiducial COLIBRE model yields gas fractions for
galaxy groups and clusters that agree with constraints from Chandra and XMM-Newton X-ray data, but which are high relative to gas fractions inferred from eROSITA stacks and measurements of the kinetic Sunyaev-Zel-dovich (kSZ) effect. COLIBRE's hybrid AGN feedback model, which combines thermal and jet-driven feedback, produces lower gas fractions in better agreement with eROSITA and kSZ measurements. COLIBRE produces lower gas fractions for groups and clusters than EAGLE and other contemporary simulations, and better agreement with observational constraints. We investigate the origin of this improvement relative to EAGLE, and how the resolution of the simulation affects the impact of feedback. Our results demonstrate that
halo gas fractions are a sensitive probe of feedback physics, and that they can differ significantly between simulations that otherwise produce very similar
galaxy populations.
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All authors Jonathan J. Davies, Joop Schaye, Filip Huško, Ruby J. Wright, Evgenii Chaikin, Matthieu Schaller, Robert J. McGibbon, Alejandro Benítez-Llambay, Sylvia Ploeckinger, Alexander J. Richings
High Energy Physics (Theory)
Wading the String Bog: CMB Birefringence in the Swampland
Guido D'Amico, Nemanja Kaloper and Alexander Westphal
We point out that observations of
cosmic birefringence may provide direct experimental tests of Swampland
conjectures. Ultralight scalar field birefringence mechanisms are constrained by Weak
Gravity Conjecture, limiting their parameter space. Conversely, confirming that CMB birefringence is caused by ultralight scalars could spell problems for the Swampland framework. Resolving these difficulties without a revision of Swampland ideology points toward thin axionic domain walls, which can explain birefringence without propagating ultralight degrees of freedom. Importantly these conflicting scenarios for
cosmic birefringence could be experimentally distinguished by a search for, or exclusion of, birefringence anisotropies, that could be measured by POLARBEAR, Simons Observatory and LiteBIRD. We also note that
cosmic birefringence observables emerge via a Sakharov-like asymmetry, where linear polarization is first generated cosmologically and subsequently twisted by a parity-violating dynamics after last scattering.
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Astrophysics of Galaxies
Superdiffusion at the Galactic Centre
Pau Amaro Seoane, Kostas Tzanavaris, Reinhard Genzel et al. (+14 more)
Tracking S-
star cluster orbits around Sgr A* calibrates orbital transport models for space-borne gravitational wave detectors. Standard kinetic theories model this cluster via local Fokker-Planck equations, which predict that general relativistic precession halts angular momentum
diffusion at the Schwarzschild barrier. Because inverse-square gravitational encounters generate a Holtsmark torque distribution with infinite variance, resonant relaxation operates as a space-fractional process governed by non-local Lévy flights. We simulate this superdiffusive continuous-time random walk using a Markov chain initialized with empirical S-
star orbits, including the recently observd S301. Integro-differential fractional operators allow trajectories to cross regions of quenched local
diffusion without density buildup at the barrier. Non-
equilibrium regimes yield immediate linear flux growth, while secular
tidal heating at periastron inflates
stellar radii to shift disruption boundaries. Regularized backward integration of the fractional transport equation traces current phase space configurations back to initial deposition states, matching the energy requirements of the
Fermi bubbles. Relativistic precession does not suppress mass-ratio inspiral rates, which provides a model for event
topologies in target
galactic nuclei.
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All authors Pau Amaro Seoane, Kostas Tzanavaris, Reinhard Genzel, Frank Eisenhauer, Thomas Ott, Stefan Gillessen, Guillaume Bourdarot, Diogo C. Ribeiro, Matteo Sadun Bordoni, Simran Joharle, Felix Mang, Andreas Burkert, Jorge Cuadra, Diego Calderón, Hagai B. Perets, Tsvi Piran, Re'em Sari
Astrophysics of Galaxies
Semi-analytic Inference of Satellite Densities in the Cold Dark Matter Model Part I. Comparison to Ultra-faint Dwarf Kinematics
Kailash Raman, Dylan Folsom, Manoj Kaplinghat et al. (+2 more)
Ultra-faint
dwarf galaxies are critical testing grounds for probing the limits of
galaxy formation in the cold dark matter (CDM) paradigm. Employing a semi-analytic cosmological satellite generator that captures the expected CDM
halo population, we estimate Milky Way
dwarf density profiles through two methods: a kinematic approach using
stellar velocity dispersions and a separate method based on
dwarf stellar masses. The kinematic approach yields a larger diversity in central dark matter densities than expected from the CDM population, as inferred from the
stellar-to-
halo mass relation, with compact ultra-faints appearing overdense and larger systems appearing underdense. For the ultra-faint
dwarfs with at least 10
stars with spectroscopic measurements, this discrepancy persists at the ~2.4$\sigma$ level across all considered systematic variations on the semi-analytic modeling. Our framework introduces a novel, robust procedure for testing the consistency of the observed population of Milky Way satellites with cosmological expectations. As future surveys discover new
dwarf satellites and refine
stellar velocity measurements, updating this analysis will provide an increasingly stringent test of the CDM paradigm.
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All authors Kailash Raman, Dylan Folsom, Manoj Kaplinghat, Mariangela Lisanti, Benjamin R. Safdi
High Energy Physics (Phenomenology)
The Very Nearly Right Theory of Flavor
Nima Arkani-Hamed, Carolina Figueiredo, Lawrence J. Hall et al. (+1 more)
A striking empirical observation about the CKM
matrix is that the angles of the unitarity triangle $(\alpha, \beta, \gamma)$ are very close to $(\pi/2, \pi/8, 3 \pi/8) $, simple fractions of $\pi$ that are suggestive of an underlying theory linking
flavor and spontaneous CP violation. However, relating this empirical observation to an underlying theory of
flavor is challenging, since the unitarity triangle is a complicated function of the Yukawa
matrices. In this letter we present a simple picture for the Yukawas where this direct link is possible. We begin by parametrizing the ten-dimensional space of
flavor data via "nine-link textures", full-rank $Y_{u,d}$
matrices with a total of nine non-zero entries, with a single CP violating phase. Fitting the ten parameters of all such textures to the
flavor data reveals a wonderful surprise: the CP phases cluster tightly around multiples of $\pi/8$! This happens because the entries of $Y_{u,d}$ naturally define a "Yukawa triangle", in most cases identical to the unitarity triangle at leading order in small
flavor parameters. Most interestingly, these two triangles are not the same beyond leading order, yielding precise predictions for $(\alpha, \beta, \gamma)$ with calculable deviation from $(\pi/2, \pi/8, 3 \pi/8)$, which can be decisively excluded or strongly confirmed by the next generation of experimental measurements of the angles. The 9-link textures are sparse and their determinants are naturally real, which taken together with spontaneous CP violation can resolve the strong CP problem.
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All authors Nima Arkani-Hamed, Carolina Figueiredo, Lawrence J. Hall, Claudio Andrea Manzari
High Energy Physics (Phenomenology)
The Dark Dimension meets the Axiverse
Kevin Langhoff, Maria Ramos and Mario Reig
We explore the cosmological implications of combining dark dimension scenarios with an axiverse. If gauge sectors are realized on branes, towers of Kaluza-Klein (KK) excitations of closed string
axions can propagate through the dark dimension in addition to the tower of graviton excitations. This modifies cosmology in two ways. First, if any of these
axion towers interact with the standard model (SM)
plasma, they can significantly alter the freeze-in production of the cosmological abundance of tower states. Freeze-in to graviton and
axion towers can provide all of dark matter (DM) for an
axion decay constant in $10^{12} \text{ GeV }\lesssim f_a\lesssim 10^{16}\,\text{ GeV }$ and reheating temperatures $5\text{ MeV }\lesssim T_{\rm RH} \lesssim O(1)\,\text{ GeV }$. Second, different towers fragment into each other and redistribute energy; each tower's fraction of energy at late times is fixed by their interactions. If there are $N\gg1$
axion towers, the energy visibly injected into the SM by any decaying tower is diluted by a factor of $N$. This suppression offers a simple realization of how dark dimension dark matter can avoid strong cosmological constraints which rule out the simplest models. In the process of this exploration we develop a continuum approach to evaluating tower fragmentation which offers insight and aids numerical calculations by reducing the problem to quadrature.
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High Energy Physics (Phenomenology)
Suppressed Quantum Effects of Weakly Coupled Waves
Yunjia Bao, Dhong Yeon Cheong, Nicholas L. Rodd et al. (+3 more)
Precision experiments increasingly target weakly coupled waves, including
axion dark matter and gravitational radiation. Such waves are commonly described as classical fields, yet they could exist in
quantum states with no classical counterpart. We exhibit two severe obstructions to detecting nonclassical effects, both independent of the mode occupancy. First, realistic detectors cannot resolve the fundamental modes of a field; instead they couple to coarse-grained "effective" modes, which often washes out nonclassical effects. Second, all nonclassical effects are suppressed by extra powers of the weak coupling, making them much harder to detect than the waves themselves. We prove this in general, and explicitly show how the suppression arises for quadrature and number statistics,
entanglement, and decoherence. The suppression can in principle be overcome given suitable
quantum resources, such as highly squeezed detector states, but the required parameters are far beyond current experimental capabilities. We use the
axion cavity haloscope as an explicit example, although our conclusions apply to many ultralight dark matter searches, and rule out proposals to establish the quantization of
gravity from observations of gravitational waves.
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All authors Yunjia Bao, Dhong Yeon Cheong, Nicholas L. Rodd, Joey Takach, Lian-Tao Wang, Kevin Zhou
Cosmology and Nongalactic Astrophysics
Andrew Liu, Anirudh Prabhu, Akaxia Cruz et al. (+1 more)
Dark matter that self interacts through long-range forces exhibits coherent, collective effects that are absent in short-range interactions. In the case where dark matter interacts through a hidden-
photon mediator, its dynamics closely resemble those of Standard Model
plasmas. In such models, various astrophysical environments, including cluster collisions and subhalos orbiting their host
halo, are susceptible to
plasma instabilities: processes that modify the dark matter velocity distribution and lead to exponential growth of dark electromagnetic fields. In this paper, we present the first study of the non-linear
evolution of electrostatic instabilities in dark matter subhalos orbiting within the Milky Way potential using a suite of particle-in-
cell simulations. We find that the growth and saturation of these instabilities produce substantial turbulent heating and mass loss, with an efficiency that depends sensitively on subhalo mass and orbital eccentricity. For highly eccentric orbits,
plasma heating can reduce the initial mass of a $10^7$ ($10^9$) $\text{M}_\odot$ subhalo by as much as $\sim 97\%$ ($\sim 84\%$) soon after first pericenter.
Plasma-induced heating and stripping may therefore leave observable signatures in the Milky Way subhalo population, including a suppression of the low-mass subhalo mass function.
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All authors Andrew Liu, Anirudh Prabhu, Akaxia Cruz, Mariangela Lisanti
Instrumentation and Methods for Astrophysics
Assessing the Impact of Instrumental Requirements on the Scientific Performance of the Einstein Telescope
Ulyana Dupletsa, Francesco Iacovelli, Mikhail Korobko et al. (+23 more)
We investigate the relationship between instrumental requirements and the scientific performance of the Einstein
Telescope (ET), a third-generation (3G) gravitational-wave (GW) observatory. Different technical design choices result in distinct noise budgets, ultimately shaping the detector's scientific capabilities. To systematically assess and compare their impact, we define a comprehensive set of performance metrics spanning compact binary coalescence (CBC) detection and parameter estimation, as well as other sources, including
stochastic GW backgrounds, isolated spinning
neutron stars, and core-collapse
supernovae (CCSNe). We build a comparative reference framework that links degradations in specific noise contributions and frequency bands to losses in scientific capabilities. We consider a representative selection of technical parameters, such as coating and suspension temperatures, the filter cavity length in the low-frequency instrument, and the beam size in the high-frequency instrument. We evaluate how sensitivity variations across specific frequency bands affect different scientific objectives. We quantify how the sensitivity below 30 Hz impacts the detectability of massive and/or high-
redshift sources and the reconstruction of long-duration CBC signals, affecting early warning and sky localization for binary
neutron stars (BNSs). Sensitivity in the 30-450 Hz range governs most CBC parameter-estimation metrics, while high-frequency sensitivity above ~450 Hz predominantly impacts BNS post-merger studies and CCSN detectability, with modest effects on detection rates. Even with the most significant degradations considered, the ET science case remains robust overall. Our results provide a comprehensive
benchmark linking scientific objectives to instrumental requirements, particularly important as the final design and infrastructure of 3G observatories are being defined.
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All authors Ulyana Dupletsa, Francesco Iacovelli, Mikhail Korobko, Valeria Sequino, Alessandro Agapito, Manuel Arca Sedda, Biswajit Banerjee, Nicolò Cibrario, Andrea Cozzumbo, Francesco Crescimbeni, Alessio Ludovico De Santis, Gabriele Franciolini, Yufeng Li, Michele Mancarella, Benedetta Mestichelli, Niccolò Muttoni, Lavinia Paiella, Ippocratis D. Saltas, Filippo Santoliquido, Pawan Tiwari, Cristiano Ugolini, Marica Branchesi, Archisman Ghosh, Jan Harms, Michele Maggiore, Fiodor Sorrentino
High Energy Physics (Experiment)
Search for heavy Majorana neutrinos in vector boson scattering with $\tau$-lepton final states with the ATLAS detector
ATLAS Collaboration
A search for heavy Majorana
neutrinos coupling to third-generation
leptons in vector
boson scattering at the LHC is presented. The search is performed in the final state with a same-sign $\tau\tau$, $e\tau$ or $\mu\tau$ pair using data of
proton–
proton collisions at $\sqrt{s}$ = 13 TeV, recorded with the ATLAS detector and corresponding to an integrated luminosity of 140 $\text{fb}^{-1}$. No significant deviation from the Standard Model background is observed. Constraints on the squared mixing
matrix element between the $\tau$-
lepton and the heavy Majorana
neutrino ($|V_{\tau N}|^2$) are derived for heavy Majorana
neutrino masses between 92 GeV and 6.5 TeV. Additionally, two-dimensional constraints on ($|V_{eN}|^{2}, |V_{\tau N}|^{2}$) and ($|V_{\mu N}|^{2}, |V_{\tau N}|^{2}$) are set. These results improve the limits on heavy Majorana
neutrinos coupling to third-generation
leptons for heavy Majorana
neutrino masses above 1.0 TeV, and extend the exclusion limits to an unexplored mass range above 1.5 TeV.
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Mesoscale and Nanoscale Physics
Harnessing Native Chromium Oxidation for Giant Orbital Torque and Field-Free Magnetization Switching in NiFe/Cr Bilayers
Chirag Kalouni, Abhishek Kumar, Manish Kumar Mohanta et al. (+6 more)
Orbital currents offer charge-to-
spin conversion beyond the efficiency limit of conventional heavy-metal
Spin Hall sources. However, harnessing them has so far required either thick orbital-
Hall materials or additional heavy-metal conversion layers. Here, we show that the native
oxide of chromium, typically regarded as parasitic, transforms a simple NiFe\Cr
bilayer into a self-contained dual-channel orbital-current source without the need for any conversion layer. First-principles calculations predict a nearly threefold enhancement of the orbital
Hall conductivity upon surface oxygenation, driven by Cr(3d)-O(2p) hybridization. Experimentally, naturally oxidized NiFe\Cr
heterostructures exhibit a
giant damping-like torque efficiency of $3.9 \times 10^{6}$ $\Omega^{-1}$ m$^{-1}$, exceeding Pt (Ta) by one (two) orders of magnitude. The torque depicts a non-monotonic Cr-thickness dependence which cannot be explained by a conventional model. We have developed a drift-
diffusion model with an oxidation-gated interfacial source which quantitatively reproduces the data, revealing that the Cr-CrO$_x$ interface generates orbital currents over an order of magnitude stronger than the bulk orbital
Hall channel with an orbital transport length of $\approx 4$ nm. The enhanced torque enables field-free magnetization switching at $1.58 \times 10^{11}$ A m$^{-2}$, outperforming heavy-metal and CuO$_x$
benchmarks. These results establish native oxidation as a scalable strategy for realizing efficient orbital-torque devices.
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All authors Chirag Kalouni, Abhishek Kumar, Manish Kumar Mohanta, Kanupriya, Athira Ravindran K, Damanpreet Kaur, Preet Kamal, Puru Jena, Debangsu Roy
Pattern Formation and Solitons
Mean-Field Theory of Chiral Active Model B: Arrested Coarsening and Chiral Fingering Instabilities
Kristian Blom and Uwe Thiele
We derive and analyze a mean-field theory of the
chiral Ising model recently introduced by Wang, Pietzonka, and Jülicher in "Edge Currents Shape Condensates in
Chiral Active Matter", arXiv:2603.20064. Starting from the master equation for clockwise and counterclockwise rotations of 2x2
spin blocks, we first obtain spatially discrete
evolution equations for the spatially resolved average magnetization. On this discrete level, we show that a
chiral bias strongly affects phase coarsening: domains coarsen anisotropically, develop nearly rectangular shapes, and eventually display chirality-induced arrested coarsening. Taking the continuum limit of these equations yields an active field theory that has the structure of a relaxational Model-B-type dynamics supplemented by a
chiral current that permanently drives the system out of
equilibrium. The coarse graining explicitly shows how microscopic rotational bias generates tangential currents localized at interfaces. Using this continuum theory, we perform a linear stability analysis of radially symmetric clusters and identify a
chiral fingering instability in which angular perturbations of the interface are amplified and eventually lead to radially asymmetric rotating states or disordered states.
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