<p>We report on a search for axion dark matter in the frequency range near 5.9 GHz, conducted using the haloscope technique. The experiment employed an 8-cell microwave resonator designed to extend the accessible frequency range by a multifold factor relative to conventional single-cell configurations, while maintaining a large detection volume. To enhance sensitivity, a flux-driven Josephson parametric amplifier operating near the quantum noise limit was utilized, together with a sideband-summing method that coherently combines mirrored spectral components generated by the Josephson parametric amplifier. Data were acquired over the frequency range 5.83–5.94 GHz. With no statistically significant excess observed, we exclude axion-photon couplings <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>g</mi></mrow><mrow><mi>a</mi><mi>γ</mi><mi>γ</mi></mrow></msub></mrow></math> down to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1.2</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>14</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mrow><msup><mrow><mi>GeV</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></mrow></math> at a 90% confidence level. The achieved sensitivity approaches the Kim-Shifman-Vainshtein-Zakharov benchmark prediction, setting the most stringent limits to date in this range.</p>

South Korea

Saebyeok Ahn

Çağlar Kutlu

Soohyung Lee

SungWoo Youn

Sergey V. Uchaikin

Sungjae Bae

Sweden

Junu Jeong

Japan

Arjan F. van Loo

Yasunobu Nakamura

Seongjeong Oh

Jihn E. Kim

Yannis K. Semertzidis

Probing Kim-Shifman-Vainshtein-Zakharov Axion Dark Matter near 5.9 GHz Using an 8-Cell Cavity Haloscope

<p>Axions, originally proposed to resolve the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>C</mi><mi>P</mi></mrow></math> problem in the strong interaction, remain a leading dark matter candidate. While cavity haloscopes offer the most sensitive technique for detecting axions, searches have largely been limited to masses below <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>10</mn><mtext> </mtext><mtext> </mtext><mi>μeV</mi></mrow></math>. We report a sensitive search for axion dark matter with masses around <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>21</mn><mtext> </mtext><mtext> </mtext><mi>μeV</mi></mrow></math>, utilizing the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>TM</mi></mrow><mrow><mn>020</mn></mrow></msub></mrow></math> mode of a cylindrical cavity equipped with an innovative tuning mechanism. Our search achieved a sensitivity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1.7</mn><mo>×</mo></math> the Kim-Shifman-Vainshtein-Zakharov benchmark over a 100-MHz range, representing a significant advance in this mass range. These results demonstrate that higher-order modes provide a viable strategy for extending haloscope searches into previously unexplored higher-mass regions.</p>

Germany

Younggeun Kim

Jinsu Kim

Seonjeong Oh

Taehyeon Seong

Sergey Uchaikin

Axion Dark Matter Search with Sensitivity near the Kim-Shifman-Vainshtein-Zakharov Benchmark Using the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>TM</mi></mrow><mrow><mn>020</mn></mrow></msub></mrow></math> Mode

We construct infinitely many new $$ \frac{1}{16} $$ -BPS cohomologies of the 4d maximal super-Yang-Mills theory and interpret them as a black hole wrapped by dual giant graviton hairs. Since the black hole inside a dual giant feels the RR 5-form flux reduced by one unit, its microstate should essentially be an SU($\textit{N}$ – 1) cohomology. However, due to the fortuitous nature of the black hole microstates, promoting an SU($\textit{N}$ – 1) black hole state to SU($\textit{N}$) generally fails to yield a cohomology. We show at $\textit{N}$ = 3 that suitable fusion products with the dual giants yield cohomologies. The core black hole size is probed by the minimal size of the dual giant which can wrap it. We also discuss two types of large black hole hairs: large conformal descendants of gravitons and large dual giants. We prove that any SU($\textit{N}$) black hole cohomology admits infinitely many hairs of the first type.

China

South Africa

Robert Mello Koch

Minkyoo Kim

Seok Kim

Jehyun Lee

Belgium

Siyul Lee

Brane-fused black hole operators

Sunjin Choi

Eunwoo Lee

United States

Jaemo Park

Erratum to: Towards quantum black hole microstates

We study new cohomologies for the BPS operators of the   <math> <mi>N</mi> </math>  $$ \mathcal{N} $$  = 4 Yang-Mills theory with SU(3) and SU(4) gauge groups, to better understand the black hole microstates. We first study the index of these black hole operators and identify their apparent threshold levels. For SU(3), we find many towers of states and partial no-hair behaviors. We explicitly construct the threshold cohomology in the SU(3) theory. We study throughout this paper a subsector of the field theory corresponding to the BMN matrix theory. We also argue that the BMN sector exhibits a black hole like entropy growth at large N.

Jaehyeok Choi

Finite N black hole cohomologies

We study the partition functions of BPS vortices and magnetic monopole operators, in gauge theories describing N M2-branes. In particular, we explore two closely related methods to study the Cardy limit of the index on S 2 × ℝ. The first method uses the factorization of this index to vortex partition functions, while the second one uses a continuum approximation for the monopole charge sums. Monopole condensation confines most of the N 2 degrees of freedom except   <math> <msup> <mi>N</mi> <mfrac> <mn>3</mn> <mn>2</mn> </mfrac> </msup> </math>  $$ {N}^{\frac{3}{2}} $$  of them, even in the high temperature deconfined phase. The resulting large N free energy statistically accounts for the Bekenstein-Hawking entropy of large BPS black holes in AdS4 × S 7. Our Cardy free energy also suggests a finite N version of the   <math> <msup> <mi>N</mi> <mfrac> <mn>3</mn> <mn>2</mn> </mfrac> </msup> </math>  $$ {N}^{\frac{3}{2}} $$  degrees of freedom.

Italy

Chiung Hwang

Quantum vortices, M2-branes and black holes

The BPS spectrum of AdS/CFT exhibits multi-gravitons at low energies, while having black hole states at higher energies. This can be studied concretely in AdS5/CFT4 in terms of classical cohomologies, even in the quantum regimes at finite 1/N. Recently, Chang and Lin found a threshold for non-graviton states in the SU(2) maximal super-Yang-Mills theory. We explicitly construct and present this threshold cohomology.

The shape of non-graviton operators for SU(2)

We study supersymmetric AdS6 black holes at large angular momenta, from the index of 5d SCFTs on S 4 × ℝ in the large N and Cardy limit. Our examples are the strong coupling limits of 5d gauge theories on the D4-D8-O8 system. The large N free energy scales like N 5/2, statistically accounting for the entropy of large black holes in AdS6. Instanton solitons play subtle roles to realize these deconfined degrees of freedom.

Large AdS6 black holes from CFT5

We study the large N matrix model for the index of 4d   <math> <mi>N</mi> </math>  $$ \mathcal{N} $$  = 4 Yang-Mills theory and its truncations to understand the dual AdS5 black holes. Numerical studies of the truncated models provide insights on the black hole physics, some of which we investigate analytically with the full Yang-Mills matrix model. In particular, we find many branches of saddle points which describe the known black hole solutions. We analytically construct the saddle points dual to the small black holes whose sizes are much smaller than the AdS radius. They include the asymptotically flat BMPV black holes embedded in large AdS with novel thermodynamic instabilities.

CERN

Saebyeok Jeong

The Yang-Mills duals of small AdS black holes

We study the cohomology of local BPS operators in $$ \mathcal{N} $$ = 4 Yang-Mills theory. The finite cohomologies consist of the graviton part (subject to the stringy exclusion principle) and the rest which may describe black hole microstates in quantum AdS/CFT. We construct an infinite tower of non-graviton cohomologies in the SU(2) theory and study to what extent they simulate quantum black holes. We find signals for partial no-hair behaviors by showing that certain gravitons are forbidden to dress these cohomologies. This is in qualitative agreement with the perturbative hairs allowed around black holes, which also leads us to a natural setup to construct hairy BPS black holes. The cohomologies are simpler to study in the BMN matrix model truncation of the classical field theory.

Towards quantum black hole microstates