We show that a QCD dilaton field, whose vacuum expectation value sets the strong coupling, can render the quantum chromodynamic (QCD) confinement transition first order. The QCD dilaton is cosmologically attracted to a false vacuum at weak coupling in the early Universe. Quantum tunneling toward the true vacuum triggers prompt chiral symmetry breaking and confinement of QCD, leading to detonating bubbles of the hadronic phase. We find that plasma sound waves produced by this dilaton-induced, first-order QCD phase transition generate a stochastic gravitational wave signal strikingly similar to the recently detected gravitational wave background from pulsar timing arrays. We briefly comment on how this theory can be probed through collider experiments and cosmology.

Sweden

Aleksandr Chatrchyan

M.C. David Marsh

Charalampos Nikolis

Gravitational Waves from a Dilaton-Induced, First-Order QCD Phase Transition

The thermal confinement phase transition in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><mi>SU</mi></mrow><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></mrow></math> Yang-Mills theory is first order for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>N</mi><mo>≥</mo><mn>3</mn></mrow></math>, with bounce action scaling as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math>. Remarkably, lattice data for the action include a small coefficient whose presence likely strongly alters the phase transition dynamics. We give evidence, utilizing insights from softly broken supersymmetric Yang-Mills models, that the small coefficient originates from a deconfined phase instability just below the critical temperature. We predict the maximum achievable supercooling in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>SU</mi></mrow><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></math> theories to be a few percent, which can be tested on the lattice. We briefly discuss the potentially significant suppression of the associated cosmological gravitational wave signals.

United Kingdom

United States

Prateek Agrawal

Gaurang Ramakant Kane

Vazha Loladze

John March-Russell

Prediction for Maximum Supercooling in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>SU</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></mrow></math> Confinement Transition

A black hole is expected to end its lifetime in a cataclysmic runaway burst of Hawking radiation, emitting all standard model particles with ultrahigh energies. Thus, the explosion of a nearby primordial black hole (PBH) has been proposed as a possible explanation for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>∼</mo><mn>220</mn><mtext> </mtext><mtext> </mtext><mi>PeV</mi></math> neutrino-like event recently reported by the KM3NeT Collaboration. If the event originated from a PBH, the source would need to lie at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>1</mn><mi>–</mi><mn>7</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mi>pc</mi></mrow></math>—depending on the assumed effective area—thus within the Solar System. At such proximity, the resulting flux of gamma rays and cosmic rays would be detectable at Earth. By incorporating the time-dependent field of view of gamma-ray observatories, we show that LHAASO should have recorded <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mn>10</mn><mn>8</mn></msup><mo stretchy="false">)</mo></math> events between fourteen and seven hours prior to the KM3NeT detection. IceCube and KM3NeT itself should likewise have detected of order a few hundred events in the range <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi><mo>≲</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>ν</mi></mrow></msub><mo>≲</mo><mn>1</mn><mtext> </mtext><mtext> </mtext><mi>PeV</mi></mrow></math> during the 24 h preceding the burst. The absence of any such multimessenger signal, particularly in gamma-ray data, strongly disfavors the interpretation of the KM3-230213A event as arising from evaporation in a minimal four-dimensional Schwarzschild scenario.

Brazil

Lua F.T. Airoldi

Gustavo F.S. Alves

Spain

Yuber F. Perez-Gonzalez

Gabriel M. Salla

Renata Zukanovich Funchal

Could a Primordial Black Hole Explosion Explain the Extremely High-Energy KM3NeT Neutrino Event?

Millicharged particles are well-motivated dark matter candidates arising in many extensions of the standard model. We show that, despite their tiny coupling <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>e</mi><mi>m</mi></msub></math> to photons, millicharged dark matter (mDM) in the Earth’s geomagnetic field can generate a quasistatic, monochromatic magnetic signal with angular frequency twice the mDM mass. Using null results from the SuperMAG and SNIPE Hunt collaborations, we constrain the effective charge of bosonic mDM in the mass range <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>18</mn></mrow></msup><mo>−</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>14</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mi>eV</mi></mrow></math>. The resulting upper bounds exceed stellar cooling constraints by over 13 orders of magnitude, demonstrating the power of this method.

China

Ariel Arza

Yuanlin Gong

Jing Shu

Lei Wu

Qiang Yuan

Bin Zhu

Geomagnetic Constraints on Millicharged Dark Matter

This Letter reports the first calculation of the gravitational form factors (GFFs) of the scalar glueball, performed via lattice field theory in Yang-Mills theory at a single lattice spacing. The glueball GFFs are compared with those of other hadrons as determined in previous lattice calculations, providing strong indications that glueballs have a different gluonic structure than typical hadronic states. A mass radius of 0.263(31) fm is predicted, supporting previous suggestions that the scalar glueball is significantly smaller than other hadrons.

Ryan Abbott

Daniel C. Hackett

Dimitra A. Pefkou

Switzerland

Fernando Romero-López

Phiala E. Shanahan

Lattice Evidence that Scalar Glueballs Are Small

Using proton-proton collision data collected by the CMS experiment at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math> in 2016–2018, corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>140</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>fb</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math>, the first full reconstruction of the three vector <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> meson states, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>B</mi></mrow><mrow><mo>*</mo><mo>+</mo></mrow></msup></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>B</mi></mrow><mrow><mo>*</mo><mn>0</mn></mrow></msup></mrow></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi>B</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>*</mo><mn>0</mn></mrow></msubsup></mrow></math>, is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><mi>m</mi><mo stretchy="false">(</mo><msup><mrow><mi>B</mi></mrow><mrow><mo>*</mo><mo>+</mo></mrow></msup><mo stretchy="false">)</mo></mrow><mo>−</mo><mrow><mi>m</mi><mo stretchy="false">(</mo><msup><mrow><mi>B</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">)</mo></mrow><mo>=</mo><mn>45.277</mn><mo>±</mo><mn>0.039</mn><mo>±</mo><mn>0.027</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><mi>m</mi><mo stretchy="false">(</mo><msup><mrow><mi>B</mi></mrow><mrow><mo>*</mo><mn>0</mn></mrow></msup><mo stretchy="false">)</mo></mrow><mo>−</mo><mrow><mi>m</mi><mo stretchy="false">(</mo><msup><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">)</mo></mrow><mo>=</mo><mn>45.471</mn><mo>±</mo><mn>0.056</mn><mo>±</mo><mn>0.028</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><mi>m</mi><mo stretchy="false">(</mo><msubsup><mrow><mi>B</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>*</mo><mn>0</mn></mrow></msubsup><mo stretchy="false">)</mo></mrow><mo>−</mo><mrow><mi>m</mi><mo stretchy="false">(</mo><msubsup><mrow><mi>B</mi></mrow><mrow><mi>s</mi></mrow><mrow><mn>0</mn></mrow></msubsup><mo stretchy="false">)</mo></mrow><mo>=</mo><mn>49.407</mn><mo>±</mo><mn>0.132</mn><mo>±</mo><mn>0.041</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math>, where the first uncertainties are statistical and the second are systematic. These results improve on the precision of previous measurements by an order of magnitude.

Armenia

A. Hayrapetyan

V. Makarenko

A. Tumasyan

Austria

W. Adam

J.W. Andrejkovic

L. Benato

T. Bergauer

M. Dragicevic

C. Giordano

P.S. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

M. Matthewman

I. Mikulec

J. Schieck

R. Schöfbeck

D. Schwarz

M. Shooshtari

M. Sonawane

W. Waltenberger

C.E. Wulz

Belgium

T. Janssen

H. Kwon

D. Ocampo Henao

T. Van Laer

P. Van Mechelen

J. Bierkens

N. Breugelmans

J. D’Hondt

S. Dansana

A. De Moor

M. Delcourt

F. Heyen

Y. Hong

P. Kashko

S. Lowette

I. Makarenko

D. Müller

J. Song

S. Tavernier

M. Tytgat

G.P. Van Onsem

S. Van Putte

D. Vannerom

B. Bilin

B. Clerbaux

A.K. Das

I. De Bruyn

G. De Lentdecker

H. Evard

L. Favart

P. Gianneios

A. Khalilzadeh

F.A. Khan

A. Malara

M.A. Shahzad

L. Thomas

M. Vanden Bemden

C. Vander Velde

P. Vanlaer

F. Zhang

M. De Coen

D. Dobur

G. Gokbulut

J. Knolle

L. Lambrecht

D. Marckx

K. Skovpen

N. Van Den Bossche

J. van der Linden

J. Vandenbroeck

L. Wezenbeek

S. Bein

A. Benecke

A. Bethani

G. Bruno

A. Cappati

J. De Favereau De Jeneret

C. Delaere

A. Giammanco

A.O. Guzel

V. Lemaitre

J. Lidrych

P. Malek

P. Mastrapasqua

S. Turkcapar

G.A. Alves

M. Barroso Ferreira Filho

E. Coelho

C. Hensel

T. Menezes De Oliveira

C. Mora Herrera

P. Rebello Teles

M. Soeiro

E.J. Tonelli Manganote

A. Vilela Pereira

W.L. Aldá Júnior

H. Brandao Malbouisson

First Exclusive Reconstruction of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>B</mi></mrow><mrow><mo>*</mo><mo>+</mo></mrow></msup></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>B</mi></mrow><mrow><mo>*</mo><mn>0</mn></mrow></msup></mrow></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi>B</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>*</mo><mn>0</mn></mrow></msubsup></mrow></math> Mesons and Precise Measurement of Their Masses

Extracting continuum properties of quantum field theories from discretized spacetime is challenging due to lattice artifacts. Renormalization-group (RG)-improved lattice actions can preserve continuum properties, but are in general difficult to parameterize. Machine learning (ML) with gauge-equivariant convolutional neural networks provides a way to efficiently describe such actions. We test a machine-learned RG-improved lattice gauge action, the classically perfect fixed-point (FP) action, for four-dimensional SU(3) gauge theory through Monte Carlo simulations. We establish that the gradient flow of the FP action is free of tree-level discretization effects to all orders in the lattice spacing, making it classically perfect. This allows us to test the quality of improvement of the FP action, without introducing additional artifacts. We find that discretization effects in gradient-flow observables are highly suppressed and less than 1% up to lattice spacings of 0.14 fm, allowing continuum physics to be extracted from coarse lattices. The quality of improvement achieved motivates the use of the FP action in future gauge theory studies. The advantages of ML-based parameterizations also highlight the possibility of realizing quantum perfect actions in lattice gauge theory.

Kieran Holland

Andreas Ipp

David I. Müller

Urs Wenger

Machine-Learned Renormalization-Group-Improved Gauge Actions and Classically Perfect Gradient Flows

We propose a probabilistic construction of imaginary Liouville field theory based on a real (noncompactified) Gaussian free field. We argue that our theory represents the first explicit Lagrangian field theory that generates the imaginary Dorn, Otto, Zamolodchikov, and Zamolodchikov (DOZZ) constants without requiring a neutrality constraint. The validity of our theory is backed up by exact results on the behavior of the imaginary multiplicative chaos on a circle, and by numerical simulations on the theory on the sphere. In particular, the three point functions of the theory that are in a very good agreement with the imaginary DOZZ constant.

France

Romain Usciati

Colin Guillarmou

Remi Rhodes

Raoul Santachiara

Probabilistic Construction of Noncompactified Imaginary Liouville Field Theory

We propose a mechanism for the generation of magnetic fields on cosmological scales that is operative after recombination. An essential ingredient is an instability (of parametric resonance type) of the electromagnetic field driven by an oscillating pseudoscalar dark-matter field, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ϕ</mi></mrow></math>, that is coupled to the electromagnetic field tensor via a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ϕ</mi><mi>F</mi><mo>∧</mo><mi>F</mi></mrow></math> term in the Lagrangian of axion electrodynamics. We find that magnetic fields larger than the observational lower bounds can be generated soon after recombination on scales of 1 Mpc.

Canada

Robert Brandenberger

Jürg Fröhlich

South Korea

Hao Jiao

Cosmological Magnetic Fields from Ultralight Dark Matter

We numerically construct asymptotically global <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>AdS</mi><mn>3</mn></msub><mo>×</mo><msup><mi mathvariant="normal">S</mi><mn>3</mn></msup><mo>×</mo><msup><mi mathvariant="normal">T</mi><mn>4</mn></msup></math> black holes in type IIB supergravity, with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="double-struck">R</mi><mi>t</mi></msub><mo>×</mo><mrow><mi>SO</mi></mrow><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo><mo>×</mo><mrow><mi>SO</mi></mrow><mo stretchy="false">(</mo><mn>3</mn><mo stretchy="false">)</mo><mo>×</mo><mi mathvariant="normal">U</mi><mo stretchy="false">(</mo><mn>1</mn><msup><mo stretchy="false">)</mo><mn>4</mn></msup></math> symmetry, localized on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi mathvariant="normal">S</mi><mn>3</mn></msup></math> and translationally invariant along the torus. These solutions, with horizons whose spatial cross sections have <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi mathvariant="normal">S</mi><mn>4</mn></msup><mo>×</mo><msup><mi mathvariant="normal">T</mi><mn>4</mn></msup></math> topology, dominate the microcanonical ensemble at low energies. At higher energies, a first-order phase transition occurs to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>BTZ</mi><mo>×</mo><msup><mi mathvariant="normal">S</mi><mn>3</mn></msup><mo>×</mo><msup><mi mathvariant="normal">T</mi><mn>4</mn></msup></math> black holes—possessing <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="double-struck">R</mi><mi>t</mi></msub><mo>×</mo><mrow><mi>SO</mi></mrow><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo><mo>×</mo><mrow><mi>SO</mi></mrow><mo stretchy="false">(</mo><mn>4</mn><mo stretchy="false">)</mo><mo>×</mo><mi mathvariant="normal">U</mi><mo stretchy="false">(</mo><mn>1</mn><msup><mo stretchy="false">)</mo><mn>4</mn></msup></math> symmetry and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi mathvariant="normal">S</mi><mn>1</mn></msup><mo>×</mo><msup><mi mathvariant="normal">S</mi><mn>3</mn></msup><mo>×</mo><msup><mi mathvariant="normal">T</mi><mn>4</mn></msup></math> horizon topology. By the AdS/CFT correspondence, this transition reflects the spontaneous breaking of the SO(4) <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi></math> symmetry of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>D</mi><mn>1</mn><mtext>−</mtext><mi>D</mi><mn>5</mn></mrow></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>CFT</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math> to SO(3). We also compute the expectation value of the scalar operator with lowest conformal dimension in the low-energy phase. Our SO(3)-localized black holes—together with the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">U</mi><mo stretchy="false">(</mo><mn>1</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mn>2</mn></msup></mrow></math>-localized solutions of Bena et al. [<a href="http://dx.doi.org/10.1007/JHEP10(2025)165">J. High Energy Phys. 10 (2025) 165</a>.]—point to a rich landscape of novel black holes that may approach the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>CFT</mi><mn>2</mn></msub></math> “sparseness bootstrap condition,” and shed light on how macroscopic entanglement in thermal phases encodes microscopic structure via internal directions.

Óscar J.C. Dias

Jorge E. Santos

Localized <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>×</mo></mrow><msup><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>×</mo><mtext> </mtext><msup><mrow><mi mathvariant="normal">T</mi></mrow><mrow><mn>4</mn></mrow></msup></mrow></math> Black Holes