The Schwinger effect, a non-perturbative mechanism for particle production in strong fields, plays a crucial role in understanding quantum vacuum decay and high-energy phenomena, including heavy-ion collisions (HIC). Although holographic quantum chromodynamics (QCD) models have been widely used to study this effect, most treatments assume isotropy or consider only a single type of anisotropy, neglecting the interplay between spatial and magnetic anisotropies that arise in realistic HIC scenarios. A unified framework accounting for both anisotropies is needed to accurately model particle production. We investigate the Schwinger effect in a twice anisotropic holographic QCD model incorporating both spatial and magnetic anisotropies. Using the anti-de Sitter/conformal field theory correspondence, we compute the total potential of a particle-antiparticle pair to quantify how these anisotropies influence pair production. Our results show that the magnetic field (parameterized by $c_B$ and $q_3$ ) enhances the Schwinger effect by lowering and narrowing the potential barrier, while increasing spatial anisotropy (controlled by $\nu$ ) suppresses the process by raising and widening the barrier. These findings demonstrate that magnetic and spatial anisotropies exert competing effects on particle production, emphasizing the necessity of treating both concurrently in holographic models. This work advances the theoretical description of the Schwinger effect in anisotropic environments, with implications for understanding non-equilibrium dynamics in HIC and other strongly coupled systems.

China

Wen-Bin Chang

Defu Hou

Schwinger effect in a twice anisotropic holographic model * Defu Hou's research is supported in part by the National Key Research and Development Program of China (2022YFA1604900). Additionally, Defu Hou receives partial support from the National Natural Science Foundation of China (NSFC) (12435009, 12275104). Wen-Bin Chang is supported by the Ph.D. Research Startup Project at Hubei Minzu University (RZ2500000857)

Radon and its progeny constitute a major source of background in rare-event physics experiments, such as those searching for dark matter, neutrinos, and neutrinoless double <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>β</mi></math> decay, due to their origin as unavoidable decay products of natural uranium. In particular, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Rn</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>222</mn></mrow></mmultiscripts></mrow></math> and its long-lived daughter <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Pb</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>210</mn></mrow></mmultiscripts></mrow></math> can diffuse from detector material surfaces, resulting in sustained background contributions. To investigate this process, a system was developed using a controlled radon source, a vacuum chamber with a high electric field, and a thin nylon-6 film to enable deposition of radon progeny onto the film surface. Nylon-6 was selected for the initial measurement given its history in low-background experiments. We intend to systematically study diffusion in various polymers in the future. Our setup allowed for controlled study of the diffusion behavior of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Pb</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>210</mn></mrow></mmultiscripts></mrow></math> and its daughter <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Po</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>210</mn></mrow></mmultiscripts></mrow></math> under varying humidity conditions. Our results show that both <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Pb</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>210</mn></mrow></mmultiscripts></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Po</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>210</mn></mrow></mmultiscripts></mrow></math> diffuse significantly in nylon under high relative humidity, which can potentially lead to internal contamination and increased background in low-background detectors. The diffusivity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Pb</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>210</mn></mrow></mmultiscripts></mrow></math> was found to be lower than <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1.14</mn><mo>×</mo><mrow><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>15</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>cm</mi></mrow><mn>2</mn></msup><mo>/</mo><mi mathvariant="normal">s</mi></mrow></math> at 40% relative humidity (RH) and to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>4.03</mn><mo>±</mo><mn>1.01</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>13</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>cm</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>/</mo><mi mathvariant="normal">s</mi></mrow></math> at 95% RH. The diffusivity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Po</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>210</mn></mrow></mmultiscripts></mrow></math> at 95% RH was measured to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>3.94</mn><mo>±</mo><mn>0.98</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>13</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>cm</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>/</mo><mi mathvariant="normal">s</mi></mrow></math>. These findings underscore the importance of controlling environmental humidity and material exposure to radon in the design of ultralow-background experiments.

Canada

P. Adhikari

M.G. Boulay

R. Crampton

M. Perry

D. Sinclair

Diffusion of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Pb</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>210</mn></mrow></mmultiscripts></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Po</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>210</mn></mrow></mmultiscripts></mrow></math> in nylon

RHIC and LHC have injected <math altimg='si2.svg'><mrow><msup><mrow /><mn>16</mn></msup><mrow><mi mathvariant='normal'>O</mi></mrow></mrow></math> nuclei in their accelerator complexes with a focus on investigating collectivity and the origin of quark-gluon plasma signatures in small collision systems. The <math altimg='si2.svg'><mrow><msup><mrow /><mn>16</mn></msup><mrow><mi mathvariant='normal'>O</mi></mrow></mrow></math> nuclei are known to possess clusters of <math altimg='si1.svg'><mi>&#945;</mi></math>-particles ( <math altimg='si19.svg'><mrow><msup><mrow /><mn>4</mn></msup><mrow><mi mathvariant='normal'>H</mi></mrow><mi>e</mi></mrow></math>) inside the nucleus. This paper attempts to study the clustered-nuclear-geometry dependence of anisotropic flow coefficients such as elliptic flow ( <math altimg='si20.svg'><msub><mi>v</mi><mn>2</mn></msub></math>) and triangular flow ( <math altimg='si21.svg'><msub><mi>v</mi><mn>3</mn></msub></math>), which are sensitive to the nuclear geometry of colliding nuclei. The study is performed in pO and OO collisions at <math altimg='si6.svg'><mrow><msqrt><msub><mi>s</mi><mrow><mrow><mi mathvariant='normal'>N</mi></mrow><mi>N</mi></mrow></msub></msqrt><mo linebreak='goodbreak'>=</mo><mn>9.61</mn></mrow></math> TeV and 7 TeV respectively, employing a hybrid model encompassing IP-Glasma + MUSIC + iSS + UrQMD. The results of the clustered nuclear geometry are compared with those of the Woods&#8211;Saxon nuclear profile. Both initial and final state anisotropies are estimated. This study is thus one of its first kind, where the study of anisotropic flow coefficients for pO and OO collisions is presented using a hybrid hydrodynamics model. While the effect of <math altimg='si1.svg'><mi>&#945;</mi></math>-clustering in pO is found to be small, it is significant for each observable studied in OO collisions. It is also observed that the magnitude of this effect has a noteworthy dependence on the size of the 4He.

India

Hungary

Aswathy Menon Kavumpadikkal Radhakrishnan

Suraj Prasad

Finland

Neelkamal Mallick

Raghunath Sahoo

Gergely Gábor Barnaföldi

Probing the sensitivity of anisotropic flow coefficients to the initial nuclear structure in pO and OO collisions at the LHC

This paper introduces a novel systematic construction of gapped domain walls (GDWs) within the Levin-Wen (LW) model. By gluing two LW models along their open sides in a compatible way, we achieve a complete GDW classification by subsets of bulk input data, which encompass the classifications in terms of bimodule categories. A generalized bimodule structure is introduced to capture domain-wall excitations. Furthermore, we demonstrate that folding along any GDW yields a gapped boundary (GB) described by a Frobenius algebra of the input UFC for the folded model, thus bridging our GDW classification and the GB classification in [1].

Yanyan Chen

Siyuan Wang

Yu Zhao

Yuting Hu

Yidun Wan

Classification of gapped domain walls of topological orders in 2+1 dimensions: a Levin-Wen model realization

The nucleus 212Po has been produced through the fragmentation of a 238U primary beam at 1 GeV/nucleon at GSI, separated with the FRagment Separator, FRS, and studied via isomer <italic>&#947;</italic>-decay spectroscopy with the RISING setup. Two delayed previously unknown <italic>&#947;</italic> rays have been observed. One has been attributed to the E3 decay of a 21 &#8722; isomeric state feeding the <italic>&#945;</italic>-emitting 45-s (18 +) high-spin isomer. The other <italic>&#947;</italic>-ray line has been assigned to the decay of a higher-lying 23 + metastable state. These are the first observations of high-spin states above the 212Po (18 +) isomer, by virtue of the selectivity obtained via ion-by-ion identification of 238U fragmentation products. Comparison with shell-model calculations points to shortfalls in the nuclear interactions involving high- <italic>j</italic> proton and neutron orbitals, to which the region around <italic>Z</italic>&#8764;100 is sensitive.

Italy

L. Zago

A. Gottardo

J.J. Valiente-Dobón

G. Benzoni

Spain

A. Gadea

Germany

M. Górska

S. Lunardi

Zs. Podolyák

P.H. Regan

Sweden

D. Rudolph

A. Algora

G. de Angelis

D. Bazzacco

J. Benlliure

P. Boutachkov

A. Bracco

United Kingdom

A.M. Bruce

F. Camera

E. Casarejos

M.L. Cortés

F.C.L. Crespi

A. Corsi

C. Domingo-Pardo

M. Doncel

T. Engert

H. Geissel

J. Gerl

A. Goasduff

N. Goel

Poland

J. Grebosz

E. Gregor

T. Habermann

S. Klupp

I. Kojouharov

N. Kurz

S.M. Lenzi

S. Leoni

S. Mandal

R. Menegazzo

D. Mengoni

B. Million

A.I. Morales

D.R. Napoli

F. Naqvi

C. Nociforo

M. Pfützner

S. Pietri

A. Prochazka

F. Recchia

E. Sahin

H. Schaffner

A. Sharma

Slovakia

B. Sitar

D. Siwal

P. Strmen

I. Szarka

C.A. Ur

P.M. Walker

H. Weick

O. Wieland

H.J. Wollersheim

High-spin states in 212Po above the <italic>&#945;</italic>-decaying (18 +) isomer

Levin-Wen string-net models provide a construction of (2+1)D topologically ordered phases of matter with anyonic localized excitations described by the Drinfeld center of a unitary fusion category. Anyon condensation is a mechanism for phase transitions between (2+1)D topologically ordered phases. We construct an extension of Levin-Wen models in which tuning a parameter implements anyon condensation. We also describe the classification of anyons in Levin-Wen models via representation theory of the tube algebra, and use a variant of the tube algebra to classify low-energy localized excitations in the condensed phase.

United States

Jessica Christian

David Green

Peter Huston

David Penneys

A lattice model for condensation in Levin-Wen systems

Neutrinos remain mysterious. As an example, enhanced self-interactions (<math><mi>ν</mi><mi>SI</mi></math>), which would have broad implications, are allowed. At the high neutrino densities within core-collapse supernovae, <math><mi>ν</mi><mi>SI</mi></math> should be important, but robust observables have been lacking. We show that <math><mi>ν</mi><mi>SI</mi></math> make neutrinos form a tightly coupled fluid that expands under relativistic hydrodynamics. The outflow becomes either a burst or a steady-state wind; which occurs here is uncertain. Though the diffusive environment where neutrinos are produced may make a wind more likely, further work is needed to determine when each case is realized. In the burst-outflow case, <math><mi>ν</mi><mi>SI</mi></math> increase the duration of the neutrino signal, and even a simple analysis of SN 1987A data has powerful sensitivity. For the wind-outflow case, we outline several promising ideas that may lead to new observables. Combined, these results are important steps toward solving the 35-year-old puzzle of how <math><mi>ν</mi><mi>SI</mi></math> affect supernovae.

Po-Wen Chang

Ivan Esteban

John F. Beacom

Todd A. Thompson

Christopher M. Hirata

Toward Powerful Probes of Neutrino Self-Interactions in Supernovae

A realistic material may possess defects, which often bring the material new properties that have practical applications. The boundary defects of a two-dimensional topologically ordered system are thought of as an alternative way of realizing topological quantum computation. To facilitate the study of such boundary defects, in this paper, we construct an exactly solvable Hamiltonian model of topological orders with gapped boundary junctions, where the boundary defects reside, by placing the Levin-Wen model on a disk, whose gapped boundary is separated into multiple segments by junctions. We derive a formula of the ground state degeneracy and an explicit ground-state basis of our model. We propose the notion of mobile and immobile charges on the boundary and find that they are quantum observables and label the ground-state basis. Our model is computation friendly.

Hongyu Wang

Extend the Levin-Wen model to two-dimensional topological orders with gapped boundary junctions

Rare event physics demands very detailed background control, high-performance detectors, and custom analysis strategies. Cryogenic calorimeters combine all these ingredients very effectively, representing a promising tool for next-generation experiments. CUPID-0 is one of the most advanced examples of such a technique, having demonstrated its potential with several results obtained with limited exposure. In this paper, we present a further application. Exploiting the analysis of delayed coincidence, we can identify the signals caused by the $^{220}$Rn-$^{216}$Po decay sequence on an event-by-event basis. The analysis of these events allows us to extract the time differences between the two decays, leading to a new evaluation of $^{216}$Po half-life, estimated as <math><mo>(</mo><mn>143.3</mn><mo>±</mo><mn>2.8</mn><mo>)</mo></math> ms.

O. Azzolini

J.W. Beeman

F. Bellini

M. Beretta

M. Biassoni

C. Brofferio

C. Bucci

S. Capelli

L. Cardani

P. Carniti

V. Caracciolo

N. Casali

D. Chiesa

M. Clemenza

I. Colantoni

O. Cremonesi

A. Cruciani

I. Dafinei

A. D'Addabbo

S. Di Domizio

F. Ferroni

L. Gironi

France

A. Giuliani

P. Gorla

C. Gotti

G. Keppel

M. Martinez

S. Nagorny

M. Nastasi

S. Nisi

C. Nones

D. Orlandi

L. Pagnanini

M. Pallavicini

L. Pattavina

M. Pavan

G. Pessina

V. Pettinacci

S. Pirro

S. Pozzi

E. Previtali

A. Puiu

C. Rusconi

K. Schäffner

C. Tomei

M. Vignati

A. Zolotarova

Measurement of Po half-life with the CUPID-0 experiment

Half-lives of the low-lying yrast states of $^{212}$Po have been measured using the delayed coincidence fast-timing method. We report on the first measurement of the <math><msubsup><mrow><mn>4</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math> half-life, as well as a new measurement of the <math><msubsup><mrow><mn>6</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math> half-life with improved accuracy compared to previous studies. The extracted lifetime of the <math><msubsup><mrow><mn>4</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math> and <math><msubsup><mrow><mn>6</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math> state have been determined to be 100(14) ps and 1.66(28) ns respectively. With these measurements, precise values are now available for the reduced transition strengths B(E2) of all ground state band levels in $^{212}$Po up to the first <math><msup><mrow><mn>8</mn></mrow><mrow><mo>+</mo></mrow></msup></math> state, in particular B(E2; <math><msubsup><mrow><mn>4</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>→</mo><msubsup><mrow><mn>2</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math>) = 9.4(13) W.u. and B(E2;<math><msubsup><mrow><mn>6</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>→</mo><msubsup><mrow><mn>4</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math>) = 8.7(15) W.u. Comparison of the new available data with an α-clustering model calculation provides evidence that the inclusion of the α-cluster degree of freedom significantly improves agreement with experimental data compared to earlier shell model calculations.