High Energy Physics (Phenomenology)
High-Frequency Gravitational Wave Detection with Superconducting Qubits
Heechan Yi, Seong Chan Park, Kyoungchul Kong et al. (+1 more)
High-frequency gravitational waves (HFGWs) provide a unique window into high-energy and early-universe physics, yet they evade traditional macroscopic interferometry. To bridge this detection gap, we propose a novel
quantum-sensing paradigm utilizing superconducting transmon
qubits embedded in resonant microwave cavities. Through the inverse Gertsenshtein effect, HFGWs propagating in a static
magnetic field resonantly excite a cavity mode. By leveraging the characteristic
spin-2 quadrupolar pattern of the induced electromagnetic field, we position
qubits directly at the electric-field hot spots of the $\mathrm{TE}_{212}$ mode to act as localized sensors. Crucially, configuring this array as an entangled
quantum register via symmetric Dicke states unlocks a fundamental scaling advantage: the signal probability scales quadratically with the
qubit number, translating to a $h_{\min} \propto n_q^{-3/4}$ strain sensitivity scaling. We demonstrate that an idealized global register of 800
qubits reaches a strain sensitivity that surpasses standard macroscopic cavity-power limits by five orders of magnitude. Benchmarked against representative
axion-haloscope parameters, this collective
quantum enhancement decisively mitigates the profound Planck-scale suppression inherent to gravitational interactions, establishing a transformative framework for next-generation HFGW searches in the GHz band.
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All authors Heechan Yi, Seong Chan Park, Kyoungchul Kong, Myeonghun Park
Strongly Correlated Electrons
Particle-Vortex Duality of Hydrodynamics
Cenke Xu and Matthew P. A. Fisher
Equipped with the recently recognized
symmetry structure of mixed states of matter and "strong-weak spontaneous
symmetry breaking" (SW-SSB), we develop a
quantum particle-
vortex duality of emergent model-F and model-A hydrodynamics of 2d
boson/rotor systems. This duality relation demonstrates that classical hydrodynamics of 2d
bosons can be described in terms of the charge
symmetry $U(1)_c$, but also equivalently in terms of the dual (emergent) 1-form
symmetry $U(1)^{(1)}_e$, as well as $U(1)_v$ associated with the conservation of
vortices. This duality provides a bridge between the hydrodynamics of matter and magnetohydrodynamics.
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High Energy Physics (Theory)
BRST quantization of Carroll-Weyl gauged null strings
Sarthak Duary and Sourav Maji
We study the BRST quantization of the null string after completing its local gauge
symmetry by Carroll-Weyl transformations. The resulting worldsheet theory possesses three first-class constraints, $C_1 = P^2$, $C_2 = P \cdot X'$, and $C_3 = P \cdot X$, whose modes realize a Weyl-BMS
algebra. The additional Carroll-Weyl constraint qualitatively changes the
quantum gauge complex: its scalar $s$-ghost is intrinsically coupled to the BMS $bc$-ghost sector, and the anomaly analysis involves three independent cocycles rather than a single Virasoro-type central charge. Starting from the gauge-fixed action, we derive the complete Faddeev-Popov complex, construct the matter and ghost currents and the BRST charge, and evaluate their equal-time operator products in the flipped, equivalently highest-weight, representation. The matter and ghost anomaly coefficients are $(c_{LL},c_{LS},c_{SS})_{\mathrm{matter}}=(2D,-D,-D)$ and $(c_{LL},c_{LS},c_{SS})_{\mathrm{ghost}}=(-54,6,4)$. Because the corresponding central terms multiply linearly independent ghost bilinears in $Q_B^2$, BRST nilpotency requires the three conditions $D=27$, $D=6$, and $D=4$, respectively. These conditions are mutually incompatible. Consequently, there is no target-space dimension in which the minimal flat Carroll-Weyl matter-plus-ghost complex is anomaly-free in the highest-weight representation. The familiar $D=26$ condition of the ILST null string is recovered only after truncation to the two-constraint BMS subsector, which defines a different
quantum gauge complex.
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Astrophysics of Galaxies
The Fornax Cluster VLT Spectroscopic Survey - V. Mass modelling of the BCG NGC 1399 out to 150 kpc
Avinash Chaturvedi, Nicola R. Napolitano, Michael Hilker et al. (+7 more)
NGC 1399, the bright central
galaxy of the Fornax cluster, hosts an extensive population of globular clusters (GCs) extending beyond 200 kpc into its outer
halo, about 6.5 effective radii (Re). We conducted dynamical mass modelling of NGC 1399 out to 5 Re (~150 kpc), using a comprehensive radial velocity catalogue of GCs, combining data from the Fornax cluster VLT spectroscopic survey (FVSS) with prior measurements from the literature. Applying spherical Jeans equations, we performed dispersion-kurtosis modelling of NGC 1399's GC kinematics to derive its mass profile and GC orbital anisotropy. We also investigated the impact of including intra-cluster GCs in the mass modelling, selected based on spatial segregation and a velocity $\sigma$-clipping method. Our findings indicate that both cusp-like (NFW) and core-like (Burkert)
halos can reproduce the observed kinematics of GCs. Including the intra-cluster GCs in the mass modelling yields broadly consistent mass profiles for both
halo types, with the full GC sample giving a virial mass of log $\log M_{\rm vir} = 13.81 \pm 0.09~M_{\odot}$ for the NFW
halo, slightly higher than the value inferred for the Burkert
halo. Regardless of the dark matter
halo profile adopted, we observe that the intra-cluster GCs exhibit radial anisotropy in the outskirts, especially among the blue, metal-poor GCs. These results suggest that GCs in NGC 1399's outer
halo are influenced by an additional
halo component associated with the
galaxy cluster potential. The radial anisotropy observed in these outer-
halo GCs provides strong dynamical evidence supporting their
accretion from external sources, consistent with prior photometric and spectroscopic studies of GCs. This study highlights the importance of including intra-cluster GCs in dynamical mass modelling to fully account for the contribution of dark matter to the cluster gravitational potential.
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All authors Avinash Chaturvedi, Nicola R. Napolitano, Michael Hilker, Katja Fahrion, Sabine Thater, Glenn van de Ven, Michele Cantiello, Chiara Spiniello, Maurizio Paolillo, Tadeja Veršič
High Energy Physics (Phenomenology)
Abundant production of scalars and axions from phase transition bubble expansion
Isabel Garcia Garcia, Gaurang Ramakant Kane, John March-Russell et al. (+1 more)
We revisit aspects of particle production during cosmological first-order phase transitions, and show that the expansion of true-
vacuum bubbles can be a copious source of particle production. Specifically, for a massive
spin-0 field linearly coupled to the bubble profile, spherical bubbles expanding even at constant radial velocity efficiently produce particles until the local-rest-frame radius of
curvature of the bubble wall exceeds the particle Compton wavelength – contrary to the expectation that walls moving at constant speed cannot radiate. We compute the momentum spectrum of the produced particles for both accelerated and constant-velocity expansion histories, identify the regimes of coherent and incoherent production, quantify the validity of the perturbative treatment, and show that this mechanism can parametrically dominate other production processes of feebly coupled particles, including freeze-in. Our results apply to many models of light, feebly coupled particles studied in the literature, providing new sources of dark radiation and dark matter. In particular, a first-order deconfinement-confinement transition in a hidden Yang-Mills sector can abundantly produce
axion-like particles, leading to dark radiation and/or dark matter signatures over large regions of parameter space.
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All authors Isabel Garcia Garcia, Gaurang Ramakant Kane, John March-Russell, Andrea Paolini
High Energy Physics (Theory)
Zhiyao Lu and Shu-Heng Shao
We present a fermionic
lattice Hamiltonian that exactly realizes the $\mathrm{U(1)}_\mathrm{L}\times \mathrm{U(1)}_\mathrm{R}$ global
symmetry and the associated
chiral anomalies of a massless Dirac
fermion in 1+1 dimensions. The construction couples Villain
bosons to a Kitaev chain of Majorana
fermions, where the bosonic fields are essential for evading Nielsen-Ninomiya-type no-go
theorems. For two copies of our model, we realize the anomaly-free $\mathrm{U(1)}_{3450}$ global
symmetry and construct symmetric boundary conditions. We analytically demonstrate symmetric mass generation by mapping the
symmetry-preserving six-
fermion interactions to
fermion bilinear terms using fermionic T-duality. Finally, by gauging general anomaly-free global
symmetries, we obtain a broad class of
lattice chiral gauge theories. As nontrivial applications, we compute the mass spectra of the
lattice Schwinger model and the 3450 gauge theory, finding agreement with the corresponding continuum results.
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Strongly Correlated Electrons
Spin-charge separation in the triangular-lattice Hofstadter-Hubbard model
Yuntian Gu, Hui Yang, Zhehao Dai et al. (+1 more)
Recent experiments in moiré materials have enabled the realization of a variety of exotic
quantum phases. In this context, the Hofstadter-Hubbard model has been proposed as a possible setting for hosting
chiral spin liquid. Concurrently, significant progress has been recently made in the computational methods for two-dimensional many-body
fermion systems, which makes numerically studying this challenging model a real possibility in genuine 2D geometry. Motivated by these advances, we investigate the putative
chiral spin liquid phase in the triangular-
lattice Hofstadter-Hubbard model using variational Monte Carlo with neural
quantum states (NQS) and projected entangled pair states (PEPS). We observe
spin-charge separation directly in real space through numerical
spin-pumping simulation and real-time
spin and charge motion. In addition, in the context of anyonic superconductivity conjectured in this model, we find a positive two-electron binding energy on small systems, but it decreases below our numerical resolution as the system size increases. Our work demonstrates NQS and PEPS as powerful tools, capable of cross-checking each other, for diagnosing topological order and fractionalized excitations in strongly correlated electronic systems.
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All authors Yuntian Gu, Hui Yang, Zhehao Dai, Yantao Wu
Quantum Physics
Unweighted Gapped Clique Homology is $\mathsf{QMA}_1$-complete
Ryu Hayakawa
Deciding whether the clique complex of a given graph has nontrivial homology in a given dimension, under vertex-product weighting and an inverse-
polynomial spectral gap promise on the combinatorial Hodge
Laplacian, is known to be $\mathsf{QMA}_1$-hard and contained in $\mathsf{QMA}$ by King and Kohler (FOCS 2024). The vertex weights are essential in the known proof, where they provide the scale separation needed for the spectral gap analysis. We prove that, when every vertex has weight one, the problem remains $\mathsf{QMA}_1^{g_2}$-hard and is contained in $\mathsf{QMA}_1^{g_2}$, where $\mathsf{QMA}_1^{g_2}$ is $\mathsf{QMA}_1$ with the universal gate set $g_2=\{\mathsf{X},\mathsf{CX},\mathsf{CCX},H\otimes H\}$. The construction replaces weight by expansion: each vertex of the weighted complex is blown up into a clique whose size encodes its weight. The block sizes are chosen so that symmetric averages reproduce the weighted Hodge metric. The symmetric sector therefore carries the weighted
Laplacian up to a common scalar factor, while a local averaging argument gives a uniform lower bound on the orthogonal complement to the symmetric sector. Hence the weighted gap analysis transfers to an unweighted clique complex without introducing either additional low-energy states or spurious homology. Containment in $\mathsf{QMA}_1^{g_2}$ follows from Rudolph's exact linear combination of
unitaries simulation of sparse integer clique
Laplacians. The result shows that the gap promise, rather than vertex weighting, is the source of the complexity of gapped clique homology.
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High Energy Astrophysical Phenomena
AT 2022csn: A Photometrically Peculiar Optical/UV Tidal Disruption Event in a Type II AGN
Yael Dgany, Iair Arcavi, Grisha Zeltyn et al. (+18 more)
The emission mechanism and host
galaxy preference of optical/UV
tidal disruption events (TDEs) are still not entirely understood. We present observations of the TDE AT 2022csn, which is one of the most distant (d_L~726 Mpc) and luminous (L_peak=2.487^(+0.073)_(-0.067)*10^(44) erg/s) optical/UV TDEs observed to date. Although it is a spectroscopically normal H+He TDE, it shows some photometric peculiarities, exhibiting a pronounced double-peaked light curve (with peaks separated by 18.30 pm 2.84 days in the g-band), and lying in the low-temperature and large-radius end of the optical/UV TDE population. The host
galaxy of AT 2022csn shows evidence for a significant starburst within the last ~Gyr consistent with other optical/UV TDEs, but also narrow emission lines that place it within the Type II AGN region of the BPT diagram. Interaction between the TDE and a pre-existing AGN
accretion disk might explain the peculiar photometric properties. However, it is puzzling that a TDE would be visible in a Type II AGN, where according to the AGN unification picture the central region around the supermassive black hole is obscured. We suggest a few scenarios to reconcile this. AT 2022csn together with AT 2019ahk, which shows similar properties, may belong to a new subset of low-temperature, high-radius TDEs in
galaxies with Type II AGN emission features.
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All authors Yael Dgany, Iair Arcavi, Grisha Zeltyn, Sebastian Gomez, Daichi Hiramatsu, Benny Trakhtenbrot, Megan Newsome, Dalya Baron, Craig Pellegrino, Jamison Burke, Nadejda Blagorodnova, David Jones, Gerard-Garcia Moreno, Erez A. Zimmerman, Asaf Horowicz, Avishay Gal-Yam, Mariusz Gromadzki, Edo Berger, Sara Faris, D. Andrew Howell, Harsh Kumar
Quantum Physics
Structure of matrix product locally purifiable density operators
Yale Yauk, Yuhan Liu and Ignacio Cirac
Tensor network methods provide powerful analytical and numerical tools for characterizing
quantum phases of matter. While the mathematical structure of
matrix product states (MPS) is well understood through the MPS fundamental
theorem, an analogous understanding for mixed-state tensor networks remains largely absent: if two purification tensors generate the same density
matrix, how are they related? In this work, we initiate the study of a fundamental
theorem for
matrix product locally purifiable density operators (LPDOs) and focus on sequentially generated LPDOs (sLPDOs), a broad subclass admitting an interpretation in terms of successive applications of
quantum channels on an initial state. We prove that, under suitable invertibility or cyclic conditions, two sLPDO representations generate the same density
matrix for arbitrary system sizes if and only if they are related by a
matrix product isometry acting on the purification bonds. Beyond the sLPDO setting, we provide a counterexample that suggests an obstruction to a general fundamental
theorem for LPDOs with periodic boundary conditions. Finally, we discuss implications for mixed-state
symmetry-protected topological phases, including the possibility of nontrivial phases protected only by weak
symmetry conditions.
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Instrumentation and Methods for Astrophysics
The Research Impact of the Jodrell Bank Observatory and Other Facilities affected by the UK Science Funding Cuts in 2025
Rommulus Francis Lewis, Amruth Alfred and Hetansh Shah
The United Kingdom Research and Innovation body and the Science and Technology Facilities Council recently announced funding cuts to facilities at the Jodrell Bank Observatory, specifically the e-MERLIN network of
radio telescopes as well as a few other facilities across the world like the James Clerk Maxwell
Telescope. These funding cuts have been extremely disturbing to the Astronomical community, as is evident from widespread news coverage about these cuts. Here we present a short analysis of the research impact e-MERLIN and the other affected facilities had in 2025 from a
dataset consisting of every Astrophysics paper submitted to the arXiv during the year. This serves to help members of the community and all stakeholders make better sense of the research output of the facilities that are not being prioritised under the new budget.
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Strongly Correlated Electrons
Tabin Dharanikota and Lukasz Fidkowski
We construct an exactly solvable
Hamiltonian lattice model realizing a 1+1d Dirac
fermion, with exact microscopic vector and axial vector $U(1)$
symmetries. The mixed anomaly between these is accommodated by the not-on-site action of the
symmetries. Our
Hilbert space is a $Z_2$-graded tensor product of local $Z_2$-graded
Hilbert spaces which include infinite dimensional rotor degrees of freedom. The
Hamiltonian becomes manifestly exactly solvable after a locality-preserving
unitary mapping to an equivalent fermionic Villain
Hilbert space. Our construction also allows an exactly solvable realization of interacting fermionic Luttinger
liquids. At the free Dirac fixed point, our
Hamiltonian contains irrelevant interactions, which we compute to leading order.
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Solar and Stellar Astrophysics
Something new under the Sun: A magnetically driven CH/CN anti-correlation
Y. Momany, L. Monaco, S. Villanova et al. (+11 more)
Spectroscopic monitoring surveys have shown that the
magnetic cycle alters the photospheric structure of the Sun, perturbing the formation of molecular lines. In parallel, the study of Globular Clusters has remained centred on the multiple
stellar populations conundrum, a phenomenon defined-most notably-by the anti-correlation between CH and CN molecular bands, serving to distinguish between first-population and second-population
stars. We systematically monitored the behaviour of the CH and CN molecular bands as a function of the
solar magnetic cycle. We demonstrate that the disc-integrated
solar spectrum exhibits a distinct CH/CN anti-correlation driven by the
magnetic cycle. Our results suggest that the spectroscopic and photometric anomalies defining the multiple populations conundrum may be physically linked to a differential spectral response to varying degrees of surface
magnetic coverage.
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All authors Y. Momany, L. Monaco, S. Villanova, S. Zaggia, I. Saviane, L. Girardi, G. Volpato, G. Costa, N.R. Landin, I. Yegorova, M. Montalto, M. Dima, F. R. Herpich, F. Almeida-Fernandes
High Energy Physics (Theory)
Thermal Order in the Biconical Model
Michael Smolkin and Lev Yung
Thermal fluctuations are generally expected to destroy order and restore
symmetries at sufficiently high temperatures. Recently, however, a family of scalar theories in $2+1$ dimensions was shown to exhibit $\mathbb Z_2$
symmetry breaking that persists to arbitrarily high temperatures using a variety of approaches, including the $\epsilon$-expansion, the FRG, and large-$N$ techniques. Although the similarities among these theories suggest that they belong to the same universality class, this connection has not been established explicitly. In this work, we fill this gap. Using large-$N$ methods, we analytically study the biconical vector model in a range of spacetime dimensions, including $2+1$, at leading and next-to-leading order in the $1/N$ expansion. We determine the RG flow, fixed-point structure, and the CFT data of the infrared theory, reproducing and extending previous results and thereby unifying the apparently distinct constructions within a common analytic framework. We derive the effective potential, establish its stable minima at zero and finite temperature, and demonstrate spontaneous $\mathbb{Z}_2$
symmetry breaking at arbitrarily high temperatures for large finite $N$.
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High Energy Physics (Theory)
Partial Waves for Multipositivity
Jaehoon Jeong
We develop a partial-wave formalism providing the missing
spin-resolved framework for multipositivity among massless planar amplitudes. We present a systematic procedure for constructing kinematic charts realizing the complex-forward limit. Applying it to obtain the four-, five-, and six-point charts, we show how to derive the one-to-two and one-to-three wavefunctions and construct the associated partial waves. The resulting formalism places higher-point multipositivity on the same footing as conventional partial-wave analyses of two-to-two scattering.
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High Energy Physics (Phenomenology)
The Forward Neutrino Flux and its Secondaries at a 10 TeV Muon Collider
Ju-Yeol Choi, Matheus Hostert, Peiran Li et al. (+1 more)
Muon decays in a
muon collider ring would produce TeV
neutrino and antineutrino beams of electron and
muon flavor. We study this flux in the forward $\mu^+$ and $\mu^-$ beam directions at a 10 TeV
muon collider and introduce \mint, a dedicated Monte Carlo simulation to model
neutrino fluxes accounting for
muon beam dynamics. We find that a
benchmark detector at 5 km from the interaction point would see about $\mathcal{O}(10^{9})$
neutrino interactions per year in a $\sim3$~tonne fiducial volume with a beam spot size of $\mathcal{O}(1)$~meter. We calculate the number of secondary
muons and
neutrinos generated by
neutrino interactions in the rock upstream of the forward detectors and find that about two secondary high-energy and highly polarized
muons from the rock would cross each detector per bunch crossing.
Neutrino productions of charmed
mesons and taus in the rock generate a small $\nu_\tau+\bar\nu_\tau$ secondary flux, with $\mathcal{O}(0.2)$ events per year in the detectors, likely too small to be observed. Wrong-sign
neutrinos from similar processes, such as $\nu_e+\bar\nu_\mu$ in the $\mu^-$ beam, are more numerous but still a fraction no larger than $\mathcal{O}(10^{-8})$ of the number of TeV
neutrino interactions. Finally, we outline how the large forward
neutrino exposure can be used to search for beyond-the-Standard-Model particles produced in
neutrino interactions, with examples of heavy neutral
leptons coupled to electron and
muon flavors through mixing or electromagnetic dipole operators.
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All authors Ju-Yeol Choi, Matheus Hostert, Peiran Li, Zhen Liu
High Energy Physics (Theory)
$\mathcal{N}=2$ RG flows, Non-Invertible Symmetries and Matrix Factorisations
Federico Ambrosino, Matthias R. Gaberdiel and Yu Nakayama
We study the behaviour of the topological defect lines of the $k^{\rm th}$ ${\cal N}=2$ minimal models that are preserved by the least relevant perturbation to first order. It is usually believed that these defects should then also define
symmetries of the IR theory, which for the usual "massless” flow should be the $(k-2)^{\rm nd}$ ${\cal N}=2$ minimal model. Using CFT arguments we show that this is not possible. We also reproduce this result using
matrix factorisation techniques: while the corresponding B-type defects can be adjusted to first order in the deformation, there is an obstruction at second order, which is associated with a supersymmetry anomaly. By contrast, for the associated massive integrable flow, which corresponds to a Chebyshev deformation of the superpotential, all of these defects can be consistently deformed, and they indeed define
symmetries of the massive IR theory.
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Statistical Mechanics
Universal crossovers in weakly-monitored quantum critical states
Abhishek Kumar, Rushikesh A. Patil, Andreas W. W. Ludwig et al. (+1 more)
We study post-measurement ensembles of ground states of tricritical and critical 1D
quantum Ising
Hamiltonians subjected, respectively, to weak energy and
spin measurements without post-selection. These measurements act as relevant perturbations about the unmeasured critical ground states. Using finite-size renormalization group (RG) crossover analyses, we characterize their universal properties through the
entanglement effective central charge, effective Affleck-Ludwig boundary
entropy, and signatures of multifractality from moments of measurement-averaged correlation functions. In both cases, we find evidence for "measurement-dominated" or "measurement-altered" fixed points governed by the underlying Born-rule randomness. For critical Ising, we find a direct RG flow to a projective-measurement fixed point with area-law
entanglement, whereas for the tricritical Ising model, we find evidence for a weak-measurement fixed point with logarithmic
entanglement. These results clarify the RG-flow structure of weakly measured multicritical Ising ground states and show how intrinsic measurement-induced randomness can generate complex and rich universal long-distance scaling behavior in the post-measurement ensembles, accessible to controlled analytical RG and numerical finite-size RG crossover analyses.
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All authors Abhishek Kumar, Rushikesh A. Patil, Andreas W. W. Ludwig, Romain Vasseur
High Energy Physics (Theory)
Krylov Complexity and $c$-function along RG Flows
Carlos Nunez and Dibakar Roychowdhury
We investigate Krylov spread complexity along
holographic renormalisation-group flows using the proposal that its growth rate is captured by the proper radial momentum of an in-falling massive probe. We focus on the second time derivative of the complexity ${U}$, which is determined locally by the
redshift and radial metric functions of the dual geometry. For Lorentz-invariant domain-wall flows preserving the spacetime dimension, we derive a new relation between ${U}$ and the covariant central charge $c_{\text{cov}}$. The decrease of the covariant central function towards the infrared is accompanied by a monotonic increase of the complexity acceleration. For the top-down Dp-brane family, we obtain a universal relation. We then examine flows across dimensions, including a twisted compactification from four to two dimensions and from six to four dimensions. In these examples $c_{\rm cov}$ and ${U }$ are co-monotonic, in sharp contrast with the inverse correlation characteristic of fixed-dimensional flows. We argue that this reversal reflects the reorganisation, rather than simple depletion, of degrees of freedom into lower-dimensional sectors under compactification. Our results identify complexity acceleration as a sensitive
geometric diagnostic connecting information spreading,
holographic central functions and RG
evolution.
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High Energy Physics (Phenomenology)
Francis M. Burk, Tao Han, Wolfgang Kilian et al. (+3 more)
While
muon colliders are primarily considered precision machines for new physics searches at the energy frontier, they are also intense sources of high-energy
neutrinos. Large fluxes of electron and
muon neutrinos are produced in the decay of beam
muons, especially along the straight sections around the experiments. In this work, we re-evaluate these
neutrino fluxes using the latest design of a \SI{10}{TeV}
muon collider and find that fluxes around the interaction region are almost two orders of magnitude higher than earlier estimates. We also compute the fluxes of
neutrinos produced in $\mu^+\mu^-$ collisions, electromagnetic showers induced by electrons from
muon decay, and interactions of
neutrinos close to the
collider ring. We find that these additional
neutrino sources are non-negligible and would lead to a sizable number of
neutrino interactions of all
flavors, including several tau
neutrino events, in a ton-scale detector placed in the forward direction. We discuss the physics opportunities offered by
muon collider neutrinos in the context of QCD and
nuclear physics, electroweak precision measurements, and searches for new physics.
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All authors Francis M. Burk, Tao Han, Wolfgang Kilian, Felix Kling, Joachim Kopp, Zahra Tabrizi
Materials Science
Investigation of GeSn aspect ratio trapping growth up to 8% Sn
Hryhorii Stanchu, Quang Minh Thai, Fernando M. de Oliveira et al. (+10 more)
Aspect ratio trapping (ART) growth of germanium-tin (GeSn) is a promising approach to target important objectives on the quest towards commercialization of complementary metal-
oxide-
semiconductor (CMOS)-compatible GeSn optoelectronics devices. Its local growth on patterned substrate allows for versatile device integration into photonics integrated
circuit or for stand-alone structure like focal plane array imager. Additionally, high aspect ratio from nano-sized window can terminate early threading dislocation propagation on the
oxide sidewalls, leaving subsequent growth defect-free and potentially improving the device performance. Knowledge remains missing regarding GeSn ART growth kinetics, morphology and how they evolve from thin film growth, with successful growth itself yet to be demonstrated. In this work, we report GeSn ART growth up to 8% Sn. Two configurations – self-induced Ge core/GeSn shell for Sn content between 6% and 8%, and bulk GeSn ART for Sn content below 1% – are observed. We present a comprehensive study on GeSn ART growth kinetics through different growth rounds and designs, showing a link between pyramid shape of ART island and successful Sn incorporation, as well as the role of growth selectivity and local heating.
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All authors Hryhorii Stanchu, Quang Minh Thai, Fernando M. de Oliveira, Mourad Benamara, Stephen Margiotta, Matthew Cook, Xiaoxin Wang, Jifeng Liu, Perry C. Grant, Baohua Li, Wei Du, Gregory Salamo, Shui-Qing Yu
Mathematical Physics
Discrete Unique Continuation on Simplex
Linjun Li
For integers $N\ge0$ and $n\ge2$, let \[ \Delta_N^{(n)} =\left\{\alpha\in\mathbb Z_{\ge 0}^n: \alpha_1+\cdots+\alpha_n=N\right\}. \] We study discrete unique continuation for functions on this
lattice simplex. For an integer $R\ge1$, let $g:\Delta_{nR}^{(n)}\to\mathbb R$ satisfy \[ \sum_{i=1}^n g(\beta+e_i)=0, \qquad \beta\in\Delta_{nR-1}^{(n)}, \] where $e_i$ is the $i$th standard basis vector. We prove that nonvanishing at the center implies \[ |\operatorname{supp} g|\ge c_n R^{\lceil n/2\rceil}. \] Here $\operatorname{supp} g$ is the set of points where $g$ is nonzero, and $c_n>0$ depends only on $n$. The exponent $\lceil n/2\rceil$ is optimal. The proof represents the values of $g$ as
polynomial coefficients and uses a Pascal uncertainty principle, which bounds from below the total number of nonzero coefficients of a one-variable
polynomial and its unit translate in terms of their degree.
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Accelerator Physics
A diagnostic system of 5.7 keV muon beam for muon accelerator
M. Wada, M. Kimura, S. Aritome et al. (+28 more)
Realization of a low-emittance
muon beam through the acceleration of keV-scale
muons requires the injection of a suitably matched beam into an accelerator, since beam mismatch can lead to emittance growth and reduced acceleration efficiency. In one such scheme,
muons are first thermalized to room temperature and then injected into a linear accelerator. Non-destructive diagnostics are challenging because of the low energy and low intensity. We developed a compact low-energy
muon diagnostic system compatible with the accelerator under construction at J-PARC. The system is designed to evaluate beam conditions required for precise tuning prior to acceleration. Commissioning with low-energy
muon sources shows the system's capability to identify low-energy
muon signals and measure beam profiles.
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All authors M. Wada, M. Kimura, S. Aritome, E. Cicek, K. Futatsukawa, K. Hirai, M. Hoshiai, T. Iijima, Y. Imai, K. Inami, K. Ishida, S. Kamioka, Y. Kawase, A. Kondo, Y. Kondo, M. Lyu, T. Mibe, Y. Nagatani, Y. Nakazawa, S. Ogawa, Y. Oishi, M. Otani, N. Saito, K. Shimomura, K. Suzuki, T. Takayanagi, K. Ueda, S. Uetake, S. Yamamoto, T. Yamazaki, M. Yang
Mathematical Physics
The $q$-extension of iterated integrals and nested sums in quantum field theory
J. Blümlein, A.M. Gavrilik, O. Mykhailiv et al. (+1 more)
Analytic calculations of zero- and single-scale quantities in perturbative
quantum field theory result into special numbers and functions, the first of which have been revealed during the last decades. These are generalizations of the polylogarithm in form of Kummer-Poincaré iterative integrals over special alphabets and extensions thereof.With growing order in the coupling constant, the polylogarithms, Nielsen integrals, the iterated integrals over linear denominator terms, cyclotomic letters, letters induced by quadratic forms, square-root valued letters, and more general functions contribute. For the nested sums we consider nested harmonic sums, generalized harmonic sums, nested sums implied by quadratic forms, cyclotomic harmonic sums, and nested sums containing central binomials. We construct the $q$-extensions of these special functions and of the nested sums, which are associated to them by the series expansion at $x=0$, and their Mellin transform in the $q$-free case. These functions are expected to play a role in perturbative calculations in the case of $q$-deformed commutation relations. For the simpler function spaces closed form solutions are presented. For more involved alphabets we present the algorithmic steps leading to the $q$-extension for the individual cases. We also derive the determining differential and difference equations of these higher transcendental functions. The $q$-extended special functions are quite different form the corresponding $\mu$-extended functions.
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All authors J. Blümlein, A.M. Gavrilik, O. Mykhailiv, C. Schneider
High Energy Physics (Phenomenology)
Rank and Scale Tests of Shell-Motivated Fermion-Mass Ansatze with a Constrained Neutrino Extension
Yaroslav D. Krivenko-Emetov and Oleksii M. Lytvynenko
We study whether the observed hierarchy of
quark and
lepton masses can be described by a small set of simple relations between the three
fermion generations. Using the nine charged-
fermion Yukawa couplings at the common scale M_Z, we distinguish genuine mass relations from those that arise simply because a model has enough freedom to reproduce the data. A systematic scan of projector-based models identifies a particularly accurate relation between the first- and third-generation mass slopes. We then construct more restrictive models that also constrain the second generation and test them by leave-one-out reconstruction. Several six-parameter models predict all nine charged masses with errors of only a few percent; the best fixed models reduce the worst leave-one-out error to about 4% without adding continuous parameters. We also give a possible microscopic interpretation of the most successful integer relations. Two mass-independent combinations of Standard-Model
quantum numbers reproduce the required charged-sector pattern, and simple twofold or threefold matching classes fix the relative coefficient before the masses are used. In a separate two-loop running test, a down-sector ratio close to 1/15 near 6 x 10^6 GeV evolves to a value close to 1/14 at M_Z. The same framework gives
neutrino-mass sums near 0.059-0.061 eV for normal ordering, while one family also allows inverted ordering near 0.103 eV. These results do not prove preons or
fermion compositeness, but provide concrete targets for future microscopic models.
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High Energy Physics (Theory)
Size Operator and Spectral Clustering in the Two Coupled SYK Model
Juan Santos-Suárez, Martí Berenguer, Javier Mas et al. (+1 more)
At large $N$, two coupled Sachdev-Ye-Kitaev models realize an eternal traversable wormhole with a discrete spectrum. We show that at finite $N$ the spectrum organizes into clusters labeled by operator size. Low-size clusters evolve into the conformal towers and define a weak-ergodicity-breaking subspace responsible for the long-lived wormhole revival dynamics. Moreover, the competition between size energy and size
entropy provides a microscopic interpretation of the wormhole-black hole transition. These results reveal operator size as the bridge between the finite-$N$ spectrum and the emergent gravitational physics at large $N$.
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All authors Juan Santos-Suárez, Martí Berenguer, Javier Mas, Alfonso V. Ramallo
Astrophysics of Galaxies
Discovery of the Distant, Ultra-Faint Milky Way Satellite Aquarius IV with the Vera C. Rubin Observatory Early Data Preview 2
William Cerny, Aashay Pai, Alex Drlica-Wagner et al. (+16 more)
We present the discovery of Aquarius IV (Rubin J2201$-$0234) – the first ultra-faint Milky Way satellite to be identified using data from the Vera C. Rubin Observatory. This system was detected at $\sim$8$\sigma$ significance using Rubin Early Data Preview 2 (EDP2) photometry and independently confirmed at $\sim$6$\sigma$ significance in archival Dark Energy Camera imaging. Jointly fitting its morphology and distance, we find that Aquarius IV is a low-luminosity ($M_V=-1.9^{+0.6}_{-1.0}$), compact ($r_{1/2} = 19^{+4}_{-6}$ pc; $r_h = 0.60^{+0.14}_{-0.17}$ arcmin)
stellar system in the outer
Galactic halo ($D_{\odot} = 109^{+6}_{-8}\ \mathrm{kpc}$). Its
stellar population is consistent with an ancient, metal-poor
stellar isochrone ($\tau = 13$ Gyr, $Z=0.0001$). These properties closely resemble those of the smallest and faintest confirmed ultra-faint
dwarf galaxies, though a globular cluster classification is not ruled out. Given the small number of detected member
stars in Rubin EDP2, deeper imaging and spectroscopy will be critical for determining the properties and classification of Aquarius IV at higher confidence.
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All authors William Cerny, Aashay Pai, Alex Drlica-Wagner, Andrew B. Pace, Peter S. Ferguson, Marla Geha, Chin Yi Tan, Sasha Campana, Jeffrey L. Carlin, Denija Crnojević, Alexander P. Ji, Guilherme Limberg, Pol Massana, Sidney Mau, Gustavo E. Medina, Burçin Mutlu-Pakdil, Joanna D. Sakowska, Nora Shipp, Guy S. Stringfellow
Quantum Physics
A Unified Complexity Framework for Quantum Property Testing
Qisheng Wang
We develop a unified framework for analyzing the complexity of
quantum property testing through functionals of the form $\mathcal{L}_{\phi}(\rho) = \operatorname{tr}(\phi(d\rho))/d$, where $\rho$ is an unknown $d$-dimensional
quantum state and $\phi$ is a given function. A master
theorem is established that derives sample complexity lower bounds for estimating $\mathcal{L}_\phi(\rho)$ from properties of $\phi$, combining Haar-random moment encoding with moment matching and best
polynomial approximation. Corresponding query complexity lower bounds follow from
quantum sample-to-query lifting. The framework yields (nearly) tight bounds for a broad class of problems, including
entropy estimation (von Neumann, Rényi, and Tsallis), closeness estimation (trace distance and Uhlmann fidelity), spectrum estimation, rank testing (operator rank, Schmidt rank, and
matrix product states). In particular, combined with known upper bounds, we show that the sample complexity of von Neumann
entropy estimation is \[ \Theta\!\left(\frac{d^2}{\varepsilon\log^2(d)\max\{1, \varepsilon\log^2(d)\}} + \frac{\log^2(d)}{\varepsilon^2}\right), \] and the sample complexity of spectrum estimation is \[ \Theta\!\left(\frac{d^2}{\varepsilon^2\log^2(d)\max\{1, \varepsilon^2\log^2(d)\}}\right). \] In summary, our results resolve several open problems and establish the optimality of 37
quantum algorithms since 2015, up to constant or polylogarithmic factors.
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Instrumentation and Methods for Astrophysics
SDSS-V Local Volume Mapper (LVM): Dithered Data Cube Reconstruction with 3dcubegen
H. J. Ibarra-Medel, A. Z. Lugo-Aranda, R. de J. Zermeño et al. (+16 more)
The Sloan Digital Sky Survey V (SDSS-V) Local Volume Mapper (LVM) is conducting an unprecedented wide-field integral field spectroscopic survey of the Milky Way, the Magellanic Clouds, and nearby
galaxies using a strategy based on multiple dithered observations to achieve full spatial coverage, improved spatial sampling, and enhanced spectral depth. However, the scientific exploitation of these observations requires a robust methodology to combine the individual row-stacked spectra (RSS) into homogeneous three-dimensional data cubes. In this work, we present 3DCubeGen, a flexible and scalable reconstruction tool designed to combine multiple LVM dithers while preserving flux and propagating uncertainties. The method enables the coaddition of large
datasets, improving the signal-to-noise ratio, enhancing spatial resolution, and increasing sensitivity to faint emission features, following and extending approaches previously implemented in integral field surveys such as CALIFA. We apply 3DCubeGen to a large set of LVM observations, including the Large and Small Magellanic Clouds and nearby
galaxies, combining thousands of dithers corresponding to millions of spectra. The resulting data products demonstrate significant improvements in spatial sampling and spectral depth, enabling detailed studies of the ionised gas,
stellar populations, and kinematics across extended regions. 3DCubeGen provides a robust and scalable solution for LVM data cube reconstruction and represents a key tool for exploiting the scientific potential of the SDSS-V Local Volume Mapper.
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All authors H. J. Ibarra-Medel, A. Z. Lugo-Aranda, R. de J. Zermeño, Sebastián F. Sánchez, Lesly Castañeda-Carlos, J. Eduardo Méndez-Delgado, K. Kreckel, Roeland P. van der Marel, R. Orozco-Duarte, Aida Wofford, Castalia Alenka Negrete, Irene Cruz-González, Carlos G. Román-Zúñiga, Guillermo A. Blanc, Evelyn J. Johnston, Ivan Katkov, Alfredo J. Mejía-Narváez, Tony Wong, Oleg V. Egorov
Quantum Physics · Cross-listed from cs.CC
An Argmax Principle for Sum-of-Squares Relaxations on the Sphere
Fernando Jeronimo Granha, Pei Wu and Haochen Xu
We develop an argmax principle for analyzing sum-of-squares relaxations of optimization problems over the unit sphere. Given a feasible pseudo-expectation, we form a
polynomial of high-order pseudo-moments, such as $\Phi_k(u)=\widetilde{\mathbb E}\langle x,u\rangle^{2k}$. Our guiding principle is that its maximizers are rounding candidates: their local and global optimality conditions reveal the reweighed pseudo-expectation inequalities governing SoS convergence. This viewpoint unifies several problems previously analyzed by rather different techniques. We obtain three results. First, for Best Separable State, we give a degree-$O(\sqrt{n/\epsilon})$ SoS analysis for approximating $h_{\mathrm{sep}}(P)$ in the perfect-completeness regime, improving and simplifying Barak, Kothari and Steurer (STOC'17). The dependence is essentially tight for inverse-linear gap under the Exponential-Time Hypothesis, matching hardness from $\mathrm{QMA}(2)$ protocols. Second, for the
matrix $2\to4$ norm, degree-$O(\sqrt n/\epsilon)$ SoS gives a multiplicative $(1+\epsilon)$ approximation. Barak et al. (STOC'12) previously gave a comparable-time constant-gap decision
algorithm; our result gives a multiplicative guarantee and extends to a family of $p\to q$ norms with even $q$. Finally, for degree-$d$
polynomial optimization, we recover the convergence
theorem of Bhattiprolu et al. (FOCS'17) with a shorter, more direct proof: degree-$k$ SoS gives approximation ratio $O_d((n/k)^{d/2-1})$. The paper introduces no new relaxation. Instead, the high-moment argmax gives a common way to read an SoS solution, unifying previously separate convergence analyses and yielding sharper bounds or simpler proofs.
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