Simultaneous measurement of mass and radius with high precision is essential to unravelling the equation of state of matter at the core of neutron stars. Measurement of massive pulsars indicates that they have to be stiff at low densities. In this work, an ensemble of agnostically constructed equations of state was studied for the mass-radius measurement. The radius of neutron stars obtained from the ensemble was confined within a 10.5–14.5 km bound. Among the NICER measurements, PSR J0437–4715 provides the most stringent constraint on the equation of state. It was found that the detection of stars with smaller radii would prefer a softer equation of state, and the detection of stars with larger radii would prefer a stiffer equation of state. However, irrespective of the detection of stars with a smaller or larger radius, the sound speed peak indicates that stars are likely to have a smooth phase transition at a few times saturation densities, and the matter at the core may not be pure conformal quark matter. A better precision of the radius measurement drastically increases the chances of constraining the equation of state. The equation of state would be more effectively constrained if the measurement of large-radius stars with high precision were to happen. Precise radius measurements of neutron stars with smaller radii provide limited constraints on the equation of state over the density range relevant to neutron stars, largely independent of the stellar mass. Also, measurements for different masses are necessary to constrain the equation of state at all density ranges relevant to neutron stars.

India

Asim Saha

Ritam Mallick

The prospect of confining the equation of state of neutron stars with future mass and radius measurements

We investigate the harvesting of quantum steering and its asymmetry between two static detectors locally interacting with a vacuum massless scalar field near an infinite, perfectly reflecting boundary. The detectors are arranged either parallel or orthogonal to the boundary, with detector $\textit{B}$ assumed to have an energy gap greater than or equal to that of detector $\textit{A}$. It is interesting to observe that, with increasing distance between the detectors and the boundary, the boundary tends to suppress quantum steering in one direction while enhancing it in the opposite direction. In the case of identical detectors, steering is symmetric when they are aligned parallel to the boundary. However, orthogonal alignment breaks this symmetry due to their unequal spatial proximity to the boundary. For non-identical detectors in the parallel configuration, the steering from $\textit{A}$ to $\textit{B}$ ($\textit{A}$ → $\textit{B}$) generally surpasses that from $\textit{B}$ to $\textit{A}$ ($\textit{B}$ → $\textit{A}$). In contrast, when the detectors are oriented orthogonally to the boundary, the relative strength of $\textit{A}$ → $\textit{B}$ and $\textit{B}$ → $\textit{A}$ steerability depends on the interplay between the boundary effects and the detectors’ energy gap difference. Across most of the parameter space, the orthogonal alignment tends to enhance $\textit{B}$ → $\textit{A}$ steering while suppressing $\textit{A}$ → $\textit{B}$ steering compared to the parallel setup. These findings suggest that boundary configurations should be flexibly adjusted according to the directional dependence of steering harvesting in order to optimize quantum information extraction.

China

Xiao-Li Huang

Xiao-Ying Jiang

Yu-Xuan Wang

Si-Yu Liu

Zejun Wang

Shu-Min Wu

Can boundary configuration be tuned to optimize directional quantum steering harvesting?

We propose a new method to determine quark masses using ratios of the vacuum-expectation values ( ) of flowed quark bilinear operators. They can be expressed as functions of the flow time $\textit{t}$ and the $$ \overline{\textrm{MS}} $$ quark mass $$ \overline{m} $$ , which can then be determined by matching with the corresponding lattice results. Motivated by this, we evaluate these perturbatively through next-to-leading order in the strong coupling. We provide the results as expansions in the limits of small and large $$ {\overline{m}}^2t $$ . To this end, we develop a new expansion technique based on the Laplace transform. Additionally, we present numerical results with the exact mass dependence over a wide range of $$ {\overline{m}}^2t $$ . We discuss the expected perturbative precision for the mass determination based on our next-to-leading order perturbative calculations, and possible non-perturbative corrections.

Japan

Hiromasa Takaura

Germany

Robert Harlander

Switzerland

Fabian Lange

A new approach to quark mass determination using the gradient flow

Modular flavor symmetries have been proposed as a new way to address the flavor problem. It is known that they can emerge from string compactifications. We discuss this connection in detail, and show how the congruence subgroups of SL(2$\textit{,}$ ℤ), which underlie many modular flavor symmetries, emerge from stringy duality symmetries by orbifolding. This requires an analysis of massive states, which reveals a picture that is more intricate than the well-known situation on the torus. It involves towers of states of different quantum numbers, related by modular transformations. Members of different towers become massless at different points in moduli space. We also show that, at least in the ℤ orbifold, the string selection rules can be understood as discrete remnants of continuous gauge symmetries. Non-Abelian discrete flavor symmetries arise as relics of various, relatively misaligned, continuous Abelian gauge symmetries. The generators of these U(1) symmetries give rise to $$ \mathcal{CP} $$ -violating Clebsch-Gordan coefficients. If the modulus settles close to a critical point, the corresponding gauge bosons may be light enough to be searched for at future colliders.

United States

Xueqi Li

Xiang-Gan Liu

Hans Nilles

Michael Ratz

Alexander Stewart

Flavor symmetries and winding modes

We explore the relation between two distinct prescriptions for $\textit{γ}$ in dimensional regularization — the Breitenlohner Maison t’Hooft Veltman (BMHV) scheme and Naive Dimensional Regularisation (NDR). The BMHV scheme is the only algebraically consistent scheme, but necessitates chiral symmetry restoring counterterms and it is computationally more expensive, limiting its practical use. We show how the quantum effective action can be translated between both schemes and present these translation rules for the Wilson Coefficients of the Standard Model Effective Field Theory (SMEFT), that can easily be implemented into automated tools for SMEFT computations. Finally, we examine how this scheme dependence manifests itself in matching calculations, identifying the cases in which the dependence cancels in the final result. To examplify this, we consider a concrete UV scenario matched onto the SMEFT at one-loop order in both schemes. Our work aims to facilitate more accurate SMEFT computations and can be considered as a first step towards a comprehensive map between the two continuation schemes.

S. Noi

Italy

R. Gröber

P. Olgoso

Mapping between $\textit{γ}$

We study the recently introduced curve integral formalism that defines a new family of formulas for the scattering amplitudes of the colored scalar tr$\textit{ϕ}$ theory. We find that the curve integral manifests a very surprising fact about these amplitudes: the dependence on the number of particles, $\textit{n}$, and the loop order, $\textit{L}$, is effectively decoupled in these formulas. We derive the curve integrals at tree-level for all $\textit{n}$. We then show that, for higher loop-order, it suffices to study the curve integrals for $\textit{L}$-loop tadpole-like amplitudes, which have just one particle per color trace-factor. By combining these tadpole-like formulas with the tree-level results, we find formulas for the all $\textit{n}$ amplitudes at $\textit{L}$ loops. We illustrate this result by giving explicit curve integrals for all the amplitudes in the theory, including the non-planar amplitudes, through to two loops, for all $\textit{n}$.

N. Arkani-Hamed

United Kingdom

H. Frost

G. Salvatori

France

P-G. Plamondon

Canada

H. Thomas

All loop scattering for all multiplicity

Duality covariant curvature and torsion tensors in double field theory/generalized geometry are central in analyzing consistent truncations, generalized dualities, and related integrable $\textit{σ}$-models. They are constructed systematically with the help of a larger, auxiliary space in a procedure inspired by Cartan geometry originally proposed by Poláček and Siegel for bosonic strings. It pivots around a maximally isotropic group that captures the generalized structure group of the physical space. We show how dropping the isotropy condition on this group allows us to describe heterotic/type I strings. As an immediate application, we construct a new family of heterotic backgrounds that interpolates between the two-dimensional cigar and trumpet backgrounds.

Poland

Falk Hassler

David Osten

Yuho Sakatani

Duality covariant curvatures for the heterotic string

Recently, Bousso and Penington (BP) made a proposal for the entanglement wedge associated to a gravitating bulk region. In this paper, we derive this proposal in time-reflection symmetric settings using the gravitational path integral. To do this, we exploit the connection between random tensor networks (RTNs) and fixed-geometry states in gravity. We define the entropy of a bulk region in an RTN by removing tensors in that region and computing the entropy of the open legs thus generated in the “hollowed” RTN. We thus derive the BP proposal for RTNs and hence, also for fixed-geometry states in gravity. By then expressing a general holographic state as a superposition over fixed-geometry states and using a diagonal approximation, we provide a general gravitational path integral derivation of the BP proposal. We demonstrate that the saddles computing the Rényi entropy $\textit{S}$ depend on how the bulk region is gauge-invariantly specified. Nevertheless, we show that the BP proposal is universally reproduced in the $\textit{n}$ → 1 limit.

Sami Kaya

Pratik Rath

Kyle Ritchie

Hollow-grams: generalized entanglement wedges from the gravitational path integral

<p>We develop a version of fluctuating relativistic hydrodynamics in a way very different from the usual derivation: Instead of treating it as a coarse-grained deterministic theory expanded in gradients of equilibrium quantities, we treat it as a stochastic theory, characterized by partition functions in each cells, expanded in cumulants. We show that the Gaussian ansatz allows us, via the gravitational Ward identities acting as a constraint between the variance and the average, to maintain full general covariance, with hydrodynamic flow emerging as an approximate Killing vector. If the symmetry of ideal hydrodynamics, volume-preserving diffeomorphisms, is preserved, we show that linear response formulas are also generally covariant. We discuss our results and argue that in this approach, the applicability of the effective theory is parametrized around a very different quantity than the Knudsen number, offering hope of understanding the applicability of hydrodynamics to small systems.</p>

Brazil

G.M. Sampaio

G. Rabelo-Soares

G. Torrieri

Gaussian generally covariant hydrodynamics

<p>Fluctuations in ultralight dark matter produce significant metric perturbations, which may be detected by monitoring the arrival times of light from millisecond pulsars. While searches using this technique are already underway, they do not consistently account for the statistical properties of the dark matter field. The statistics of this field depend on the velocity dispersion of dark matter and, consequently, its coherence length. In the mass range relevant for pulsar timing arrays, the coherence length is comparable to separations between pulsars, making it crucial to incorporate its effects into the analysis. This Letter presents a consistent statistical method for gravitational direct detection of ultralight dark matter. Our key result is the derivation of the two-point function of the metric fluctuations, which we apply to pulsar timing and discuss its implementation in future searches.</p>

Kimberly K. Boddy

Jeff A. Dror

Austin Lam

Ultralight Dark Matter Statistics for Pulsar Timing Detection