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)

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 present a set of <math altimg='si2.svg'><mrow><mi>&#8467;</mi><mo linebreak='goodbreak'>+</mo><mn>3</mn></mrow></math> simple differential operators and prove that they annihilate an &#8467;-loop generic mass banana integral in dimensional regularization. We study the singular locus of the ideal generated by these operators and show that it is contained in the set of Landau singularities of the first and second type. Through the Macaulay matrix method, we calculate the corresponding holonomic rank up to <math altimg='si3.svg'><mrow><mi>&#8467;</mi><mo linebreak='goodbreak'>=</mo><mn>8</mn></mrow></math>, obtaining <math altimg='si4.svg'><mrow><msup><mn>2</mn><mrow><mi>&#8467;</mi><mo>+</mo><mn>1</mn></mrow></msup><mo linebreak='goodbreak'>&#8722;</mo><mn>1</mn></mrow></math>, which agrees with the number of master integrals for the generic mass banana integrals. Based on these findings, we conjecture that the proposed operators generate the annihilating ideal for the generic mass banana integrals in dimensional regularization.

Italy

Wojciech Flieger

D-ideal of generic mass banana integrals in dimensional regularization

We apply the light-cone QCD sum rules with chiral currents to compute transition form factors of the semileptonic decay of the charmed and bottom scalar mesons <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo>/</mo><mi>B</mi></math> to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo><msup><mi>l</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>l</mi></msub></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mi>l</mi><mo>=</mo><mi>e</mi><mo>,</mo><mi>μ</mi><mo stretchy="false">)</mo></mrow></math>, where the scalar meson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> are firstly regarded as two quark states, and contributions from the tetraquark component are then added via proper modulation of four distribution amplitudes considered. The obtained transition form factors and branching fraction are free of the contribution from the light-cone distribution amplitudes at the level of twist-three and two simple relations connecting their form factors are obtained. Our computations indicates that the decay branch fractions are on the margin of the measurements reported by the Beijing Spectrometer III in the pure two-quark scenario and are in good agreement with observations when tetraquark component is considered.

Di Gao

JiangShan Lan

Duojie Jia

Xingbo Zhao

Yanjun Sun

Transition form factors for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo>/</mo><mi>B</mi></math> to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> from light-cone QCD sum rules

We consider an $$\mathcal{N}=1$$ nonrenormalizable supersymmetric gauge theory with the superpotential quartic in the chiral matter superfields. With the help of the Slavnov’s higher covariant derivative regularization it is demonstrated that (in the lowest nontrivial order) the leading power divergent quantum correction to the gauge coupling constant is given by an integral of double total derivatives with respect to the loop momenta. The result obtained after calculating this integral turned out to be proportional to the corresponding quantum correction to the kinetic term of the matter superfields. More exactly, in the considered approximation the quadratically divergent contributions to the gauge coupling and to the kinetic term of the chiral matter superfields are related by an equation analogous to the exact NSVZ $$\beta $$ -function for the renormalizable case.

France

Ali Lakhal

Russia

Konstantin Stepanyantz

Relation between leading divergences in nonrenormalizable 4$\textit{D}$ supersymmetric theories

A new model based on the relativistic Boltzmann equation in the isotropization time approximation is developed to investigate the collective behavior of the quark-gluon plasma produced in high-energy heavy-ion collisions. The equation is solved in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>(</mo><mn>2</mn><mo>+</mo><mn>2</mn><mo>)</mo><mi mathvariant="normal">D</mi></mrow></math> (two spatial and two momentum-space dimensions). This framework couples preequilibrium dynamics with hydrodynamic evolution to simulate the dynamics of quasiparticle evolution. A numerical scheme based on the method of characteristics enables the evolution to begin from a specified initial Boltzmann distribution. In this work, the spatial structure of the initial distribution is modeled using the Trento framework. Our results show that a medium initialized at <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>τ</mi><mn>0</mn></msub></math> on the order of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>1</mn><mspace width="0.16em"></mspace><mi>fm</mi><mo>/</mo><mi>c</mi></mrow></math> with a small shear viscosity to entropy density ratio (<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>η</mi><mo>/</mo><mi>s</mi><mo>=</mo><mn>0.008</mn></mrow></math>) evolves consistently with hydrodynamic simulations, such as those performed using the vish2+1 code, while discrepancies arise for a medium with <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>η</mi><mo>/</mo><mi>s</mi><mo>=</mo><mn>0.8</mn></mrow></math>. Furthermore, when initialized with a highly anisotropic momentum distribution in the longitudinal direction at early times, the system exhibits spatially nonuniform thermalization in the transverse plane, leading to the emergence of a nontrivial hypersurface that marks the onset of hydrodynamic applicability. Finally, we compute the <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>p</mi><mi>T</mi></msub></math>-spectra for a nonfluctuating initial condition using the hybrid version of CoMBolt-ITA. In this hybrid setup, the description is switched from quasiparticles to hadrons, and UrQMD is used to model the hadron gas dynamics. We compare these results with those obtained from the hybrid vish2+1 initialized within the same setup. For a small shear viscosity, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>η</mi><mo>/</mo><mi>s</mi><mo>=</mo><mn>0.08</mn></mrow></math>, the two results show a good level of consistency, whereas for a larger value, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>η</mi><mo>/</mo><mi>s</mi><mo>=</mo><mn>0.8</mn></mrow></math>, a noticeable discrepancy emerges.

Germany

S.F. Taghavi

Iran

S.M.A. Tabatabaee Mehr

F. Taghinavaz

<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>(</mo><mn>2</mn><mo>+</mo><mn>2</mn><mo>)</mo><mi mathvariant="normal">D</mi></mrow></math> collective model based on a relativistic Boltzmann equation in the isotropization-time approximation: CoMBolt-ITA

The capability of the ALICE@LHC and STAR@RHIC experiments to reconstruct <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi></math> mesons has enabled femtoscopic correlation measurements of open-charm mesons in both small and large systems. In this work, we present a theoretical calculation of the correlation functions of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover></math> mesons with nucleons, based on the Koonin-Pratt formalism. We employ an effective Lagrangian to model the interaction between charmed mesons and baryons and apply the TROY formalism to obtain the off-shell <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math>-matrix in coupled channels, incorporating the effect of the Coulomb interaction when the pair involves two charged particles. The resulting full coupled-channel wave function is inserted into the Koonin-Pratt equation with channel weights derived from a thermal model. Additionally, we compute the correlation functions using the Lednický-Lyuboshitz approximation with low-energy scattering parameters extracted from the unitarized amplitudes. We compare these two approaches and provide predictions for different correlated pairs. Our results can be tested against current and future experimental data from the ALICE and STAR Collaborations in both proton-proton and heavy-ion collisions.

Spain

Mikel F. Barbat

Juan M. Torres-Rincon

Àngels Ramos

Laura Tolos

Femtoscopy of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>D</mi><mi>N</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mi>N</mi></math> systems

In light of recent precision measurements from BESIII, we reanalyze the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo>,</mo><msub><mi>D</mi><mi>s</mi></msub><mo stretchy="false">→</mo><msup><mi>η</mi><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msup></math> transition form factors using quantum chromodynamics (QCD) light-cone sum rules, incorporating high-twist contributions and well-established next-to-leading-order QCD corrections. Our analysis confirms the chiral enhancement effect arising from twist-3 light-cone distribution amplitudes of the pseudoscalar mesons, and demonstrates a rapid convergence of the operator product expansion. The resulting high-accuracy form factors enable us to determine the optimal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mo>−</mo><msup><mi>η</mi><mo>′</mo></msup></math> mixing parameters from the precise experimental data for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo>,</mo><msub><mi>D</mi><mi>s</mi></msub><mo stretchy="false">→</mo><msup><mi>η</mi><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> (with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>ℓ</mo><mo>=</mo><mi>e</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>μ</mi></mrow></math>) differential decay rates. We find that the BESIII data strongly favor a set of mixing parameters, characterized by small decay constants and a large mixing angle, in the quark flavor basis. Notably, the light-cone-sum-rule predictions for the decays <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo stretchy="false">→</mo><msup><mi>η</mi><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math>, induced by weak <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>c</mi><mo stretchy="false">→</mo><mi>d</mi></math> current, reach a precision comparable to the BESIII experimental results. Nevertheless, further refined measurements and more accurate form-factor determinations will be essential to scrutinize the potential role of gluonic components in charmed meson semileptonic decays.

Xiao-En Huang

Shan Cheng

De-Liang Yao

Semileptonic decays <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>D</mi><mrow><mo stretchy="false">(</mo><mi>s</mi><mo stretchy="false">)</mo></mrow></msub><mo stretchy="false">→</mo><msup><mi>η</mi><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> from QCD light-cone sum rules revisited

We extend the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>κ</mi></math>-symmetry analysis of supersymmetric D-brane probes in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>AdS</mi><mn>2</mn></msub><mo>×</mo><msup><mi mathvariant="bold">S</mi><mn>2</mn></msup></math> attractor geometry, originally performed by Simons, Strominger, Thompson, and Yin to also include stationary—but nonstatic—worldlines carrying angular momentum along the 2-sphere. We demonstrate that certain special trajectories, with fixed radius and orbital velocity, solve the equations of motion and moreover satisfy a supersymmetry preserving condition, thus defining new <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mfrac><mn>1</mn><mn>2</mn></mfrac></math>-BPS configurations. Furthermore, these classical paths are shown to saturate a lower bound for the Hamiltonian generating global time translations, with the corresponding minimal energy depending on a generalized angular momentum vector <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="bold-italic">J</mi></mrow></math>. The direction of the latter, in turn, determines exactly which supercharges remain unbroken. Our results reveal a richer spectrum of (multiparticle) supersymmetric states in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>×</mo><msup><mrow><mi mathvariant="bold">S</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math>, which can be organized into distinct selection sectors labeled by the conserved <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo></math> charges. This construction has direct applications in black hole microstate counting, the analysis of probe dynamics, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>AdS</mi><mn>2</mn></msub><mo>/</mo><msub><mi>CFT</mi><mn>1</mn></msub></math> holography.

United States

Alberto Castellano

Carmine Montella

Matteo Zatti

Supersymmetric D-brane probes in 4D <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>2</mn></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>×</mo><msup><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> attractors