One of the main targets for space-borne gravitational wave detectors is the detection of Extreme Mass Ratio Inspiral (EMRIs). Data analysis of EMRIs requires waveform models that are both accurate and fast. The major challenge for the fast generation of such waveforms is the generation of the Teukolsky amplitudes for generic (eccentric and inclined) Kerr orbits. The requirement for modeling $${\sim 10^5}$$ harmonic modes in a four-dimensional parameter space makes traditional approaches, including direct computation or dense interpolation, computationally prohibitive. To overcome this issue, we introduce a convolutional encoder–decoder architecture for a fast and end-to-end global fitting of the Teukolsky amplitudes. We also adopt a transfer learning strategy to reduce the size of the training dataset, and the model is gradually trained from the simplest Schwarzschild circular orbits to generic Kerr orbits step by step. Within this framework, we obtain a surrogate model based on a semi-analytical Post-Newtonian dataset, and the full harmonic amplitudes can be generated within milliseconds, while the median mode-distribution error for generic orbits is $$\sim 10^{-3}$$ . This result indicates that the framework is viable for the construction of efficient waveform models for EMRIs.

China

Yan-bo Zeng

Jian-dong Zhang

Yi-Ming Hu

Jianwei Mei

A deep learning framework for amplitude generation of generic EMRIs

I review the standard instanton framework for determining the $\textit{θ}$-dependence of instanton-dominated correlation functions in QCD. I then contrast these well-established semiclassical results with the recent assertion of refs. [1, 2] that $\textit{θ}$-phases are absent and that strong interactions preserve CP for all values of $\textit{θ}$. In all scenarios considered, the $\textit{θ}$-dependence is shown to be intrinsically non-trivial, being governed either by instantons in the weak-coupling regime or by alternative, non-perturbative considerations when the theory is strongly coupled.

United Kingdom

Valentin Khoze

A note on instantons, $\textit{θ}$-dependence and strong CP

Understanding the internal structure of the proton – including its mass spectrum, electromagnetic and gravitational form factors, and mechanical properties – remains a central challenge in hadronic physics. While lattice QCD and experimental measurements provide valuable insights, a holographic framework with a single parameter set capable of simultaneously describing these diverse observables is still lacking. Here, we employ the soft wall model, a phenomenological holographic approach that incorporates gluon condensation and linear confinement, to compute the proton mass spectrum, electromagnetic form factors (EMFFs), and gravitational form factors (GFFs). Our results show good agreement with recent experimental data and lattice QCD calculations. Despite its phenomenological nature, the model’s ability to simultaneously describe multiple observables suggests that it effectively mimics some key QCD features.

Jiali Deng

Defu Hou

Proton structure from a soft-wall holographic QCD model: mass spectrum, form factors, and mechanical properties

We investigate the optical appearance of a Kerr–Bertotti–Robinson (Kerr-BR) black hole illuminated by a geometrically and optically thin accretion disk. Instead of using a phenomenological power-law emissivity, we adopt a magnetically driven synchrotron emissivity proxy coupled to the local electromagnetic environment. With a backward ray-tracing framework, we examine the effects of the spin $\textit{a}$, magnetic parameter $\textit{B}$, and observer inclination $$\theta _O$$ on the ray-classification maps, redshift distributions, and specific-intensity images. We show that the ISCO position is modified by both $\textit{a}$ and $\textit{B}$, and that rapidly rotating prograde configurations can develop an additional model-dependent inner cutoff when the magnetically dominated approximation underlying the emissivity prescription ceases to be applicable. High-resolution one-dimensional intensity profiles further separate the direct image, the $$n=1$$ lensing-ring contribution, and the higher-order $$n\ge 2$$ photon-ring subimages, while quantifying the Doppler-induced brightness asymmetry. Retrograde disks exhibit a wider emission-depleted central region because of the outwardly shifted ISCO, making the higher-order lensed components more clearly distinguishable from the direct emission. These results show that the disk inner boundary and the magnetic-field-dependent emissivity can substantially influence the observable appearance of Kerr-BR black holes.

Zeng-Yi Zhang

Xiang-Qian Li

Hao-Peng Yan

Xiao-Jun Yue

Optical appearance of the Kerr–Bertotti–Robinson black hole with a magnetically driven synchrotron emissivity model

Yang-Mills theory in AdS with Dirichlet boundary conditions is expected to undergo a transition as the AdS radius varies, since the boundary data is incompatible with confinement in flat space. Various mechanisms have been proposed for the disappearance of the Dirichlet boundary condition. From the boundary viewpoint, the associated 3$\textit{d}$ CFT is a deformation of a generalised free theory of non-Abelian conserved currents, with the deformation governed by the bulk gauge coupling. We test these scenarios by deriving non-perturbative constraints from the numerical conformal bootstrap of the four-point function of non-Abelian conserved currents. We rule out the scenario in which the boundary current decouples. Bounds on the lightest scalar operators disfavour a bulk Higgs mechanism and instead point to a transition driven by a scalar singlet becoming marginal. We also obtain bounds on other scalar operators and on the current central charge, and we refine character-based techniques incorporating parity and charge-conjugation symmetry to determine the operator spectrum of the 3$\textit{d}$ Generalised Free Vector theory. These results may be of independent interest beyond Yang-Mills theory in AdS.

Italy

Lorenzo Pietro

Stefanos Kousvos

Marco Meineri

Alessandro Piazza

Marco Serone

Alessandro Vichi

A bootstrap study of confinement in AdS

<p>A search is performed for a new resonance <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi></math> decaying into a Higgs boson and a new scalar boson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>Y</mi></math>) including the case where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi></math> is assumed to be a second Higgs boson (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>H</mi></math>), using proton-proton collision data collected at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>, corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>138</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>. This study performs a comprehensive exploitation of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mi>b</mi><mi>Z</mi><mi>Z</mi></math> events, encompassing the following decay topologies. One <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi></math> candidate is identified through its decay into a bottom quark-antiquark pair, while the other <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi></math> or the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi></math> candidate is selected through its decay into a pair of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> bosons. One <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> boson is required to decay leptonically and the other, to decay into a pair of quarks or neutrinos. Events of interest are categorized based on the Lorentz boosts of the hadronically decaying <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> bosons. Machine-learning-based discriminants, together with the reconstructed resonance mass, are employed across the different categories to separate signal from backgrounds, and their corresponding distributions are included in a simultaneous fit. No significant deviations from the standard model predictions are observed. Upper limits at the 95% confidence level are set on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>Y</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>H</mi></math> production cross sections. For <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>Y</mi></math> production, the upper limit on the cross section of the process <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>p</mi><mi>p</mi><mo stretchy="false">→</mo><mi>X</mi><mo stretchy="false">→</mo><mrow><mi>H</mi><mi>Y</mi></mrow><mo stretchy="false">→</mo><mi>b</mi><mi>b</mi><mi>Z</mi><mi>Z</mi></math> ranges from 500 to 5 fb, with the most stringent constraints achieved for high-mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi></math> resonances and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi></math> masses near the threshold for decay into a pair of massive vector bosons. This is comparable to the sensitivity achieved in other analyses, which focus on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi></math> decays to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi><mi>γ</mi></math> or <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi><mi>τ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi></math> decays into a pair of bottom quarks or massive vector bosons. For resonant <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>H</mi></math> production, the upper limit on the cross section of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>p</mi><mi>p</mi><mo stretchy="false">→</mo><mi>X</mi><mo stretchy="false">→</mo><mrow><mi>H</mi><mi>H</mi></mrow></math> production is 1 pb for a high-mass resonance.</p>

Armenia

A. Hayrapetyan

V. Makarenko

A. Tumasyan

Austria

W. Adam

L. Benato

T. Bergauer

M. Dragicevic

P.S. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

M. Matthewman

J. Schieck

R. Schöfbeck

M. Shooshtari

M. Sonawane

N. Van Den Bossche

W. Waltenberger

C.E. Wulz

Belgium

T. Janssen

H. Kwon

D. Ocampo Henao

T. Van Laer

P. Van Mechelen

D. Ahmadi

J. Bierkens

N. Breugelmans

J. D’Hondt

S. Dansana

A. De Moor

M. Delcourt

C. Gupta

F. Heyen

Y. Hong

P. Kashko

S. Lowette

I. Makarenko

S. Nandakumar

S. Tavernier

M. Tytgat

G.P. Van Onsem

S. Van Putte

D. Vannerom

A. Beshr

B. Bilin

F. Caviglia Roman

B. Clerbaux

A.K. Das

I. De Bruyn

G. De Lentdecker

E. Ducarme

H. Evard

L. Favart

A. Khalilzadeh

A. Malara

M.A. Shahzad

A. Sharma

L. Thomas

M. Vanden Bemden

C. Vander Velde

P. Vanlaer

F. Zhang

A. Cauwels

M. De Coen

D. Dobur

C. Giordano

G. Gokbulut

K. Kaspar

D. Kavtaradze

D. Marckx

K. Skovpen

A.M. Tomaru

J. van der Linden

J. Vandenbroeck

H. Aarup Petersen

S. Bein

A. Benecke

A. Bethani

G. Bruno

A. Cappati

J. De Favereau De Jeneret

C. Delaere

F. Gameiro Casalinho

A. Giammanco

A.O. Guzel

V. Lemaitre

J. Lidrych

P. Malek

S. Turkcapar

Brazil

G.A. Alves

M. Barroso Ferreira Filho

E. Coelho

C. Hensel

D. Matos Figueiredo

T. Menezes De Oliveira

C. Mora Herrera

P. Rebello Teles

M. Soeiro

E.J. Tonelli Manganote

Search for a new resonance decaying to a Higgs boson and a scalar boson in events with two <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math> jets and two <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> bosons in proton-proton collisions at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>

<p>Recent lattice evidence may suggest the chiral phase transition in QCD is second order for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>N</mi></mrow><mrow><mi>f</mi></mrow></msub><mo>≥</mo><mn>2</mn></mrow></math> massless flavors. We constrain conformal field theory (CFT) descriptions of a critical line in temperature <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>T</mi></mrow></math> and imaginary baryon chemical potential <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>θ</mi></mrow><mrow><mi>B</mi></mrow></msub><mo>=</mo><mi>i</mi><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub><mo>/</mo><mi>T</mi></mrow></math>. An ’t Hooft anomaly at general <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>θ</mi><mi>B</mi></msub></math> constrains the transition even at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>θ</mi><mi>B</mi></msub><mo>=</mo><mn>0</mn></math>, leaving only three minimal scenarios. The best-motivated scenario for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>f</mi></msub><mo>≥</mo><mn>3</mn></math>, and perhaps also <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>f</mi></msub><mo>=</mo><mn>2</mn></math>, is beyond Ginzburg-Landau, featuring a conformal manifold of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>θ</mi><mi>B</mi></msub></math>-dependent universality classes with an exactly marginal operator related to baryon density.</p>

United States

Shi Chen

Aleksey Cherman

Robert D. Pisarski

Does Hot QCD Have a Conformal Manifold in the Chiral Limit?

We calculate the one-loop renormalization group equations of the neutrino mass matrix when the Standard Model particle content is extended with a massive gauge boson which has family-dependent couplings to the left-handed leptons. We show that quantum effects induced by the extra gauge boson increase the rank of the neutrino mass matrix at the one-loop level, in contrast to the well-known result that Standard Model fields can only increase the rank at the two-loop level. We also discuss the possibility of generating dynamically the measured mass differences and mixing angles between the active neutrinos in scenarios with normal and inverted mass ordering.

Germany

Alejandro Ibarra

Japan

Lukas Treuer

Quantum effects on neutrino parameters from a flavored gauge boson

We develop a covariant Hamiltonian formalism in which evolution is measured along the proper-time flow of an observer congruence, replacing the external coordinate-time derivative with the Lie derivative. Our formalism keeps the Hamiltonian split between evolution and configuration variables and expresses it through spacetime tensors projected relative to the chosen congruence. After quantization, the resulting observer-congruent brackets lead to relativistic Heisenberg and Schrödinger equations whose evolution parameter is proper time. We then apply this framework to gravity by taking the projected spatial metric and its conjugate momentum as canonical variables, obtaining a complete model of canonical quantum gravity. Among the predictions of this theory we find a resolution to the singularity problems in cosmology, black holes and black hole thermodynamics.

Spain

Antonio Peña

A quantum theory of gravity

Traditional diagnostics of black hole phase transitions rely on thermodynamic quantities defined at the event horizon or asymptotic boundary. Here, we demonstrate that the near-singularity geometry offers a sharp, independent probe of both first-order phase transitions and supercritical crossover. For scalarized AdS black holes exhibiting a first-order phase transition, the Kasner exponent $$p_t$$ , which characterizes the approach to the singularity, undergoes a dramatic transformation. On one side of the transition, $$p_t$$ oscillates strongly with temperature, reflecting violent interior dynamics. On the other side, it becomes a smooth, monotonically varying function. These two distinct behaviors converge as the critical point is approached. Beyond the critical point, in the supercritical region, $$p_t(T)$$ develops a distinct extremum, defining a “Kasner crossover line” that is entirely independent of traditional thermodynamic (Widom line) or dynamic (Frenkel line) criteria. Our work establishes the near-singularity geometry of scalarized black holes as a novel class of diagnostics for phase transitions, revealing that a change in the macroscopic thermodynamic state fundamentally reshapes the deepest interior structure of spacetime.