Within the framework of the thermal soft-wall model of AdS/QCD, we investigate phenomenological properties of pions at finite temperature. This includes the electromagnetic form factor <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>F</mi><mi>π</mi></msub><mo stretchy="false">(</mo><msup><mi>Q</mi><mn>2</mn></msup><mo>,</mo><mi>T</mi><mo stretchy="false">)</mo></math>, the thermal mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>M</mi><mi>π</mi></msub><mo stretchy="false">(</mo><mi>T</mi><mo stretchy="false">)</mo></math>, charge radius <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>r</mi><mi>π</mi></msub><mo stretchy="false">(</mo><mi>T</mi><mo stretchy="false">)</mo></math>, the generalized parton distribution (GPD) <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>H</mi><mi>π</mi></msub><mo stretchy="false">(</mo><mi>x</mi><mo>,</mo><msup><mi>Q</mi><mn>2</mn></msup><mo>,</mo><mi>T</mi><mo stretchy="false">)</mo></math>, the charge density <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ρ</mi><mi>π</mi></msub><mo stretchy="false">(</mo><mi>b</mi><mo>,</mo><mi>T</mi><mo stretchy="false">)</mo></math> of the pion, the pion-nucleon coupling constant <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>g</mi><mrow><mi>π</mi><mi>N</mi><mi>N</mi></mrow></msub><mo stretchy="false">(</mo><mi>T</mi><mo stretchy="false">)</mo></math>, and pion-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi></math> baryon coupling constant <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>g</mi><mrow><mi>π</mi><mi mathvariant="normal">Δ</mi><mi mathvariant="normal">Δ</mi></mrow></msub><mo stretchy="false">(</mo><mi>T</mi><mo stretchy="false">)</mo></math> coupling constant at finite temperature. The thermal pion form factor is extrapolated from the zero-temperature case. Subsequently, the GPD is obtained at finite temperature from this form factor. The above-mentioned quantities were analyzed using a thermal dilaton field in the five-dimensional anti–de Sitter action. Moreover, we determine the theoretical expression for the temperature-dependent pion-nucleon coupling constant, and the pion-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi></math> baryon coupling constant using thermal profile functions of the nucleon, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi></math> baryon and the pion. Our results show that the values of these quantities decrease with increasing temperature and vanish near the critical temperature <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>c</mi></msub></math>, except for the pion radius, which diverges at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>c</mi></msub></math>. Our results reproduce expected features of low-energy hadron dynamics, thus validating the phenomenological utility of the thermal soft-wall model.

Azerbaijan

Narmin Nasibova

United States

Xerxes D. Arsiwalla

Pion phenomenology from the thermal soft-wall model of holographic QCD

We employ deep learning within holographic duality to investigate <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math>-linear resistivity, a hallmark of strange metals. Utilizing physics-informed neural networks, we incorporate boundary data for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math>-linear resistivity and bulk differential equations into a loss function. This approach allows us to derive dilaton potentials in Einstein-Maxwell-dilaton-axion theories, capturing essential features of strange metals, such as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math>-linear resistivity and linear specific heat scaling. We also explore the impact of the resistivity slope on dilaton potentials. Regardless of slope, dilaton potentials exhibit universal exponential growth at low temperatures, driving <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math>-linear resistivity and matching infrared geometric analyses. At a specific slope, our method rediscovers the Gubser-Rocha model, a well-known holographic model of strange metals. Additionally, the robustness of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math>-linear resistivity at higher temperatures correlates with the asymptotic Anti-de Sitter behavior of the dilaton coupling to the Maxwell term. Our findings suggest that deep learning could help uncover mechanisms in holographic condensed matter systems and advance our understanding of strange metals.

South Korea

Byoungjoon Ahn

Spain

Hyun-Sik Jeong

Chang-Woo Ji

Keun-Young Kim

Kwan Yun

Deep learning-based holography for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math>-linear resistivity

Quantum forces are long-range interactions that arise only at the loop level. In this work, we study the Sommerfeld enhancement of dark matter (DM) annihilation cross sections caused by quantum forces. One notable feature of quantum forces is that they are subject to coherent enhancement in the presence of a background of mediator particles, which occurs in many situations in cosmology. We show that this effect has important implications for the Sommerfeld enhancement and DM physics. For the first time, we calculate the Sommerfeld factor induced by quantum forces for both bosonic and fermionic mediators, including the background corrections. We observe several novel features of the Sommerfeld factor that do not exist in the case of the Yukawa potential, such as temperature-induced resonance peaks for massless mediators, and having both enhancement and suppression effects in the same model with different DM masses. As direct applications, we discuss the DM phenomenology affected by the Sommerfeld enhancement from quantum forces, including thermal freeze-out, CMB spectral distortion from DM annihilation, and DM indirect detection. We highlight one particularly interesting effect relevant to indirect detection caused by the Sommerfeld enhancement in a non-thermal background of bosonic mediators in the galaxy, in which case the DM mass is shifted due to the background correction and the effective cross section for DM annihilation can be either enhanced or suppressed. This may be important for DM searches in the Milky Way or its satellite galaxies.

Steven Ferrante

Maxim Perelstein

Bingrong Yu

Sommerfeld enhancement from quantum forces for dark matter

Through the holographic correspondence, we compute the entanglement entropy of the gluonic field sourced by a quark-antiquark pair undergoing uniform back-to-back acceleration. Previous calculations had obtained this only for the case where the entanglement surface is located midway between the quark and antiquark. Here, we consider the more general case with a relative lateral displacement, and determine the entanglement entropy as a function of the distance between the quark and the entanglement surface. This setup is of interest because it departs from the usual simplifying conditions of staticity and thermality, and because it yields more information about the entanglement pattern in the gluonic field and about the possibility of eventually developing a purely worldsheet interpretation for said entanglement.

Mexico

Andrés Argandoña

Alberto Güijosa

Position dependence of the holographic entanglement entropy for an accelerating quark-antiquark pair

We revisit sterile neutrino production enabled by nonstandard interactions (NSIs) among active neutrinos mediated by new bosons. We focus on vector mediators, including neutrinophilic, gauged <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>L</mi></mrow><mrow><mi>μ</mi></mrow></msub><mo>−</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>τ</mi></mrow></msub></mrow></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>B</mi><mo>−</mo><mi>L</mi></mrow></math> realizations, that modify in-medium dispersion and scattering, thereby altering the active-sterile conversion history. Building on a novel production framework with NSI thermal potentials and collision integrals, we compute nonthermal phase-space distributions across sterile neutrino mixing and NSI parameters and map each point to an equivalent thermal warm dark matter particle mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>th</mi></msub></math> via linear theory transfer function fitting with the cosmological structure formation Boltzmann solver. This enables a direct reinterpretation of state-of-the-art structure formation limits from Milky Way satellites, strong lensing, and the Lyman-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>α</mi></math> forest. These limits, in conjunction with x-ray decay searches, as well as results from a wide variety of particle physics experiments allow for a more complete examination of these models. We find that these vector-mediated models are ruled out when the full combination of current constraints, listed above, are taken into account. NSI scalar-mediated models and models with low reheating temperatures remain viable.

Cannon M. Vogel

Helena García Escudero

Kevork N. Abazajian

Cosmic structure strikes back: The elimination of vector-mediated nonstandard interaction models as a mechanism for sterile neutrino dark matter production

We systematically investigated the limited inverse discrete Fourier transform of the quasi distributions from the perspective of inverse problem theory. This transformation satisfies two of Hadamard’s well-posedness criteria, existence and uniqueness of solutions, but critically violates the stability requirement, exhibiting exponential sensitivity to input perturbations. To address this instability, we implemented Tikhonov regularization with L-curve optimized parameters, demonstrating its validity for controlled toy model studies and real lattice QCD results of quasi distribution amplitudes. The reconstructed solutions is consistent with the physics-driven $$\lambda $$ -extrapolation method. Our analysis demonstrates that the inverse Fourier problem within the large-momentum effective theory (LaMET) framework belongs to a class of moderately tractable ill-posed problems, characterized by distinct spectral properties that differ from those of more severely unstable inverse problems encountered in other lattice QCD applications. Tikhonov regularization establishes a rigorous mathematical framework for addressing the underlying instability, enabling first-principles uncertainty quantification without relying on ansatz-based assumptions.

China

Ao-Sheng Xiong

Jun Hua

Yu-Fei Ling

Ting Wei

Fu-Sheng Yu

Qi-An Zhang

Yong Zheng

Ill-posedness in limited discrete Fourier inversion and regularization for quasi distributions in LaMET

The flavor-changing neutral current semileptonic decays of <italic>B</italic> mesons provide an excellent platform for indirectly probing New Physics (NP) beyond the Standard Model (SM). Recent measurements of lepton flavor universality (LFU) ratios such as <italic>R<inf>K</inf></italic>, <math altimg='si22.svg'><msub><mi>R</mi><msup><mi>K</mi><mo>*</mo></msup></msub></math>, and <italic>R<inf>&#981;</inf></italic> are consistent with SM predictions, thereby reducing earlier hints of LFU violation. Nevertheless, notable tensions persist in individual branching fractions&#8212;for instance <math altimg='si38.svg'><mrow><mi mathvariant='script'>B</mi><mo>(</mo><msup><mi>B</mi><mo>+</mo></msup><mo>&#8594;</mo><msup><mi>K</mi><mo>+</mo></msup><msup><mi>&#956;</mi><mo>+</mo></msup><msup><mi>&#956;</mi><mo>&#8722;</mo></msup><mo>)</mo></mrow></math> and <math altimg='si50.svg'><mrow><mi mathvariant='script'>B</mi><mo>(</mo><msup><mi>B</mi><mo>+</mo></msup><mo>&#8594;</mo><msup><mi>K</mi><mo>+</mo></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup><mo>)</mo></mrow></math>, which deviate at the 4 <italic>&#963;</italic>&#8211;5 <italic>&#963;</italic> level in the low- <italic>q</italic> 2 region ([1.1,6] GeV 2). Similarly, the angular observable <math altimg='si10.svg'><msubsup><mi>P</mi><mn>5</mn><mo>&#8242;</mo></msubsup></math> in <math altimg='si8.svg'><mrow><mi>B</mi><mo>&#8594;</mo><msup><mi>K</mi><mo>*</mo></msup><msup><mi>&#956;</mi><mo>+</mo></msup><msup><mi>&#956;</mi><mo>&#8722;</mo></msup></mrow></math> shows a 3.3 <italic>&#963;</italic> deviation, while <math altimg='si128.svg'><mrow><mi mathvariant='script'>B</mi><mo>(</mo><msub><mi>B</mi><mi>s</mi></msub><mo>&#8594;</mo><mi>&#981;</mi><msup><mi>&#956;</mi><mo>+</mo></msup><msup><mi>&#956;</mi><mo>&#8722;</mo></msup><mo>)</mo></mrow></math> departs from the SM by 3.6 <italic>&#963;</italic>. Although such discrepancies could in principle originate from underestimated hadronic effects, they may also indicate possible NP contributions. In this work, we perform a global fit to the latest <math altimg='si16.svg'><mrow><mi>b</mi><mo>&#8594;</mo><mi>s</mi><msup><mi>&#8467;</mi><mo>+</mo></msup><msup><mi>&#8467;</mi><mo>&#8722;</mo></msup></mrow></math> data within the framework of dimension-6 SMEFT operators. Our analysis systematically incorporates hadronic uncertainties from form factors, non-factorizable corrections, and input parameters, thereby providing a balanced assessment of the NP interpretation. We allow for NP contributions not only in <math altimg='si129.svg'><mrow><mi>b</mi><mo>&#8594;</mo><mi>s</mi><msup><mi>&#956;</mi><mo>+</mo></msup><msup><mi>&#956;</mi><mo>&#8722;</mo></msup></mrow></math> transitions but also in <math altimg='si130.svg'><mrow><mi>b</mi><mo>&#8594;</mo><mi>s</mi><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup></mrow></math> channels, thus testing both lepton flavor universal (LFU) and lepton flavor universality violating (LFUV) NP scenarios. The interplay between these possibilities yields distinctive signatures in branching fractions, angular observables, and &#916;-observables, offering a comprehensive view of the current flavor anomalies.

India

Md Isha Ali

Utpal Chattopadhyay

Dilip Kumar Ghosh

N. Rajeev

Constraints on lepton flavor universal and non-universal new physics in <math altimg='si127.svg'><mrow><mi>b</mi><mspace width='0.16em' /><mo>&#8594;</mo><mspace width='0.16em' /><mi>s</mi><mspace width='0.16em' /><msup><mi>&#8467;</mi><mo>+</mo></msup><msup><mi>&#8467;</mi><mo>&#8722;</mo></msup></mrow></math> decays: A global SMEFT survey

We investigate the “complexity equals anything” proposal with codimension-one and codimension-zero gravitational observables for multi-horizon black holes, using the Bardeen-AdS class black hole as an example. In particular, we compare the results with the “complexity equals volume” (CV) proposal and find that the generalized volume complexitiy enables the probing of a more complete black hole interior, that is, all spacetime regions where the blackening factor $\textit{f}$ ($\textit{r}$) < 0. This is the advantage brought by the flexibility of this holographic complexity conjecture. In addition, we compute the codimension-zero gravitational observables derived from various geometric quantities and show that these constructions can effectively differentiate the distinct interior regions of the black hole.

Hong-Yue Jiang

Yu-Xiao Liu

Complexity equals anything for multi-horizon black holes

This paper discusses a framework to parametrize and decompose operator matrix elements for particles with higher spin ($\textit{j}$ > 1$\textit{/}$2) using chiral representations of the Lorentz group, i.e. the ($\textit{j}$, 0) and (0, $\textit{j}$) representations and their parity-invariant direct sum. Unlike traditional approaches that require imposing constraints to eliminate spurious degrees of freedom, these chiral representations contain exactly the 2$\textit{j}$ + 1 components needed to describe a spin-$\textit{j}$ particle. The central objects in the construction are the $\textit{t}$-tensors, which are generalizations of the Pauli four-vector $\textit{σ}$ for higher spin. For the generalized spinors of these representations, we demonstrate how the algebra of the $\textit{t}$-tensors allows to formulate a generalization of the Dirac matrix basis for any spin. For on-shell bilinears, we show that a set consisting exclusively of covariant multipoles of order 0 ≤ $\textit{m}$ ≤ 2$\textit{j}$ forms a complete basis. We provide explicit expressions for all bilinears of the generalized Dirac matrix basis, which are valid for any spin value. As a byproduct of our derivations we present an efficient algorithm to compute the $\textit{t}$-tensor matrix elements. The formalism presented here paves the way to use a more unified approach to analyze the non-perturbative QCD structure of hadrons and nuclei across different spin values, with clear physical interpretation of the resulting distributions as covariant multipoles.

Wim Cosyn

Frank Vera

Spinor representations for fields with any spin: Lorentz tensor basis for operators and covariant multipole decomposition

Light scalars that couple to leptons are common figures in beyond the Standard Model endeavors. Considering a scalar that has universal and couplings to leptons only, we compute this leptophilic scalar contribution to the $$e^{-}e^{+} \rightarrow \tau ^{+}\tau ^{-} S $$ production cross section with $$S \rightarrow e^{+}e^{-}(\mu ^{+}\mu ^{-})$$ . We later compare the expected signal with recent data from the BELLE collaboration collected near the resonance $$\Upsilon (4S)$$ with $$\mathscr {L}=626 fb^{-1}$$ of integrated luminosity to place limits on the couplings-mass plane for the 4 MeV-6.5 GeV mass range. We then extended this analysis to a more general one $$e^{-}e^{+} \rightarrow {\ell }^{+}{\ell }^{-} S$$ production cross section where $$\ell =e,\mu ,\tau $$ with $$S \rightarrow e^{+}e^{-}(\mu ^{+}\mu ^{-})$$ , showing that BELLE constitutes an excellent laboratory for light scalars, where can be derived constraints stronger than those derived stemming from the g-2 of the electron or muon.

Brazil

D. Cogollo

Chile

Y. Oviedo-Torres

Farinaldo Queiroz

France

Yoxara Villamizar

J. Zamora-Saa

Search for sub-GeV scalars in $$e^+e^-$$ collisions