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)

Several proposed future lepton colliders are capable of producing trillions of Z-bosons, including FCC-ee, CEPC, LEP3 and LEP-Z. Such Tera-Z factories can discover new elementary particles with couplings to the Z-boson that are orders of magnitude smaller than current bounds. For couplings near the currently excluded parameter regions they could produce sufficiently large samples to study the new particles’ properties in detail, thereby serving as both a discovery and precision machine in one. Using simple analytic estimates, we quantify the dependence of the expected event yield in long-lived particle searches on the number of produced Z-bosons and on the detector dimensions. From this, we derive estimates for both the discovery reach and the measurement precision attainable at such facilities. While the precision of such estimates of course falls short of proper simulations, the analytic approach is suitable for a quick assessment of the sensitivity for a given design. We illustrate this with two examples, heavy neutral leptons and axion-like particles. Under optimistic assumptions, these could be produced in the millions and billions, respectively, effectively turning future lepton colliders into exotics factories.

Belgium

Germany

Marco Drewes

Croatia

Juraj Klarić

Yuan-Zhen Li

New particles at the Z-pole:

The notion of time in general relativity must arise from an internal clock, i.e., a degree of freedom in the gravitational theory internal to the system that can serve the role of a physical clock. One such internal notion of time is the York time, corresponding to constant extrinsic curvature slicing of spacetime. We study the Hartle-Hawking wavefunction of asymptotically $\textit{AdS}$ JT gravity as a function of York time. Using both canonical quantization and the JT gravity path integral, we explicitly calculate this wavefunction and show that it satisfies a Schrodinger equation with respect to York time. We find the corresponding York Hamiltonian, which turns out to be manifestly Hermitian. Our analysis cleanly avoids operator ordering ambiguities. The dependence of the wavefunction on York time should be thought of as emerging from a unitary basis transformation of the gravitational length basis states used to compute the wavefunction, and not from time evolution of the state in the dual boundary theory.

India

Onkar Parrikar

Japan

Sunil Sake

York time in JT gravity

In this study, we investigate the possibility of enhancing the di-jet resonance searches by tagging the final state radiation (FSR) jet using an event-level deep neural network. It is found that solely relying on the 4-momenta of the leading three jets allows the algorithm to achieve good discriminating power that can identify the hardest FSR jet in the signal while rejecting other soft jets. Once the invariant mass is corrected with the tagged FSR jet, the mass resolution of the signal is greatly enhanced, and the sensitivity of the search is also improved by more than 10%. By crafting the input variables carefully, the algorithm introduces minimal mass sculpting for the background, and its applicability extends to a broad mass range. This work proves that FSR jet tagging can potentially enhance di-jet resonance searches, suiting various stages of the physics programmes at the Large Hadron Collider (LHC) and High-Luminosity LHC (HL-LHC).

Bingxuan Liu

Yuxuan Shen

Yuanshunzi Sui

Enhancing di-jet resonance searches via a final-state radiation jet tagging algorithm * Bingxuan Liu is supported by Shenzhen Campus of the Sun Yat-sen University under project 74140-12255011, and by the Young Scientists Fund (C Class) of the National Natural Science Foundation of China (12405122). Both Yuxuan Shen and Yuanshunzi Sui are supported by College Students’ Innovative Entrepreneurial Training Plan Program

We investigate the collider signatures of a maximally flavor-violating $ U(1)_{L_\mu-L_\tau} $ model, where a new gauge boson $ Z^\prime $ and scalar triplets induce lepton flavor-changing interactions in the $\textit{μ}$-$\textit{τ}$ sector. Focusing on four-lepton final states at multi-TeV lepton colliders, we conduct a detailed analysis of cross sections, asymmetries, and polarization effects. We show that the signal cross section is highly sensitive to $ m_{Z^\prime} $ and the effective parameters $ \tilde{g}/m_{Z^\prime} $ , whereas it remains largely insensitive to the triplet Yukawa couplings within the phenomenologically allowed region. The forward-backward asymmetry exhibits a characteristic monotonic dependence on $ m_{Z^\prime} $ , and beam polarization can significantly suppress the Standard Model backgrounds while enhancing new physics contributions. We find that, in the phenomenologically allowed parameter space, the predicted observables remain highly sensitive to the underlying model parameters. These results show that multi-lepton final states are powerful probes of the $ U(1)_{L\mu - L_\tau} $ framework and can offer valuable guidance for future searches at muon and electron-positron colliders.

Jianing Qin

Fei Huang

Honglei Li

Zhi-Long Han

Jin Sun

Collider probes of four-lepton final states in maximally flavor-violating ${U(1)_{L_\mu-L_\tau}} $ model * Supported by National Natural Science Foundation of China (12505112, 11805081), Shandong Province Natural Science Foundation (ZR2024QA138, ZR2022MA056) and State Key Laboratory of Dark Matter Physics, University of Jinan Disciplinary Cross-Convergence Construction Project 2024 (XKJC- 202404) and Jin Sun is supported by IBS under the project code, (IBS-R018-D1)

We investigate and update observational constraints on cosmological parameters within the $$\Lambda $$ CDM and dynamical dark energy frameworks, using a new compilation of the transverse (or 2D) BAO data, measurements that provide a relatively model-independent estimate of the BAO angular scale at a given redshift. Firstly, we assess the consistency of this compilation with CMB-Planck data and recent BAO results from the DESI collaboration. After confirming minimal tension with CMB data, we perform a series of joint analyses combining CMB data with the 2D BAO compilation, as well as with several recent Type Ia supernova (SNIa) samples. In all cases, we compare the constraining power of the 2D BAO data with that of DESI DR2 data (3D BAO). Our results indicate that combining 2D BAO with CMB and SNIa data provides observational constraints that are in agreement with those obtained using DESI DR2 data. Although the precision of DESI DR2 results remains higher, as expected due to the more accurate 3D measurements, the 2D BAO compilation combined with other probes yields strong constraints. For example, in the $$\Lambda $$ CDM context, we find (CMB + 2D BAO): $$H_0 = 68.16^{+0.41}_{-0.37} \,\,\, \text {km s}^{-1}\,\text {Mpc}^{-1}$$ and $$\Sigma m_{\nu } < 0.081~\textrm{eV}$$ (95% CL). These results are consistent with analogous analyses using DESI DR2. Several other cases are investigated and discussed in the main text. Our results show that this new 2D BAO compilation is robust and delivers meaningful cosmological constraints. Parameters from 2D BAO alone agree with CMB-only results, with no significant tension. Overall, 2D and 3D BAO provide consistent and complementary information when combined with other probes.

Brazil

Miguel Sabogal

Rafael Nunes

Felipe Avila

Armando Bernui

Updated cosmological constraints from 2D BAO measurements: a new compilation and comparison with DESI DR2

We present a deep learning pipeline to perform a model-independent, likelihood-free search for anomalous (i.e., non-background) events in the proposed next-generation multi-ton scale liquid xenon-based direct detection experiment, DARWIN. We train an anomaly detector comprising a variational autoencoder (VAE) and a classifier on high-dimensional simulated detector response data and construct a 1D anomaly score to reject the background-only hypothesis in the presence of an excess of non-background-like events. We use simulated validation data to determine the power of the method to reject the background-only hypothesis in the presence of a WIMP dark matter signal, without any model-dependent assumption about the nature of the signal. We show that our neural networks learn relevant features of the events from low-level, high-dimensional detector outputs, avoiding lossy and computationally expensive compression into lower-dimensional observables. Our approach is complementary to the usual likelihood-based analysis, in that it reduces the reliance on many of the corrections and cuts that are traditionally part of the analysis chain, with the potential of achieving higher accuracy and significant reduction of analysis time. We envisage the methodology presented in this work augmenting or complementing likelihood-based and other data-driven methods currently utilized in the DARWIN (and in the future, XLZD) analysis pipeline.

Netherlands

J. Aalbers

K. Abe

Switzerland

M. Adrover

France

S. Maouloud

L. Althueser

United States

D. Amaral

B. Andrieu

Italy

E. Angelino

D. Antón Martin

Serbia

Bosnia and Herzegovina

B. Antunovic

E. Aprile

M. Babicz

D. Bajpai

M. Balzer

Australia

E. Barberio

L. Baudis

M. Bazyk

N. Bell

L. Bellagamba

R. Biondi

Y. Biondi

A. Bismark

C. Boehm

K. Boese

R. Braun

Israel

A. Breskin

S. Brommer

United Kingdom

A. Brown

G. Bruni

R. Budnik

C. Cai

C. Capelli

A. Chauvin

A. Chavez

A. Colijn

Sweden

J. Conrad

J. Cuenca-García

V. D’Andrea

L. Garcia

M. Decowski

A. Deisting

C. Donato

P. Gangi

S. Diglio

M. Doerenkamp

G. Drexlin

K. Eitel

A. Elykov

R. Engel

A. Ferella

C. Ferrari

H. Fischer

T. Flehmke

M. Flierman

K. Fujikawa

W. Fulgione

C. Fuselli

P. Gaemers

R. Gaior

M. Galloway

F. Gao

N. Garroum

R. Giacomobono

F. Girard

R. Glade-Beucke

F. Glück

L. Grandi

J. Grigat

R. Größle

H. Guan

M. Guida

P. Gyorgy

R. Hammann

V. Hannen

S. Hansmann-Menzemer

N. Hargittai

A. Higuera

C. Hils

K. Hiraoka

L. Hoetzsch

N. Hood

M. Iacovacci

Y. Itow

J. Jakob

R. James

F. Joerg

F. Kahlert

Y. Kaminaga

M. Kara

P. Kavrigin

S. Kazama

M. Keller

P. Kharbanda

B. Kilminster

M. Kleifges

M. Klute

M. Kobayashi

D. Koke

A. Kopec

B. Krosigk

Model-independent searches of new physics in DARWIN with deep learning

We compute the bispectrum of primordial density perturbations in CMB to second order in the slow-roll parameters of single field inflation. We correct previous results and found that next-to-leading order corrections can be of the same order as the leading order result in a large class of models, including hilltop inflation.

Thailand

Ignatios Antoniadis

Jules Cunat

Auttakit Chatrabhuti

Hiroshi Isono

New leading contributions to non-Gaussianity in single field inflation

<p>The recent low-energy electron recoil (ER) results reported by the LUX-ZEPLIN (LZ) experiment have established the most stringent constraints to date on new physics scenarios, specifically for solar axion-like particles with keV-scale masses and mirror dark matter. Motivated by this enhanced sensitivity and the resulting restrictive limits, our present work focuses on probing light mediator models via elastic neutrino-electron scattering induced by solar neutrinos. We specifically consider two broad classes of new physics scenarios; (i) universal light mediator models consistent with Lorentz invariance, including scalar, vector, and tensor interactions, and (ii) anomaly-free leptophilic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msup><mo stretchy="false">)</mo><mo>′</mo></msup></math> gauge extensions featuring a new vector mediator associated with the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>e</mi></msub><mo>−</mo><msub><mi>L</mi><mi>μ</mi></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>e</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>e</mi></msub><mo>+</mo><mn>2</mn><msub><mi>L</mi><mi>μ</mi></msub><mo>+</mo><mn>2</mn><msub><mi>L</mi><mi>τ</mi></msub></math> symmetries. By incorporating contributions from these interactions into the neutrino-electron scattering cross section and utilizing the most precise solar neutrino flux predictions, we analyze the latest LZ ER datasets. We report novel constraints on the coupling-mass parameter space for these models. Furthermore, we contextualize our findings by comparing them with established bounds from various laboratory, cosmological, and astrophysical sources. Our analysis demonstrates that LZ data provide significantly improved limits in previously unconstrained regions of the parameter space.</p>

Türkiye

Mehmet Demirci

M. Fauzi Mustamin

Solar neutrino probes of light new physics: Updated limits from LUX-ZEPLIN experiment

<p>Recently, a new framework for studying generic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mo stretchy="false">→</mo><mn>3</mn></math> hard exclusive reactions, referred to as single-diffractive hard exclusive processes, has been introduced to provide a cleaner separation of the underlying physical mechanisms. In this work, we expand this formalism to the case of exclusive real-photon electroproduction off a nucleon, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mo stretchy="false">(</mo><mo>ℓ</mo><mo stretchy="false">)</mo><mo>+</mo><mi>N</mi><mo stretchy="false">(</mo><mi>p</mi><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>e</mi><mo stretchy="false">(</mo><msup><mo>ℓ</mo><mo>′</mo></msup><mo stretchy="false">)</mo><mo>+</mo><mi>N</mi><mo stretchy="false">(</mo><msup><mi>p</mi><mo>′</mo></msup><mo stretchy="false">)</mo><mo>+</mo><mi>γ</mi><mo stretchy="false">(</mo><msup><mi>q</mi><mo>′</mo></msup><mo stretchy="false">)</mo></math>, which represents the classical channel for accessing generalized parton distributions (GPDs) in nucleons and nuclei. This extension enables a more systematic and physically transparent formulation of the reaction dynamics, paving the way for improved extractions of GPDs from experimental data as compared to existing approaches.</p>

Jian-Wei Qiu

Nobuo Sato

Zhite Yu

New framework for extracting GPDs from exclusive photon electroproduction