Crossing symmetry suggests that deep inelastic scattering and semi inclusive electron-positron annihilation are governed by analytic continuations of a single forward amplitude. Drell, Levy, and Yan proposed that the hadronic tensor admits analytic continuation and demonstrated, in reasonable models, that connected contributions to the cross-section continue. They also identified obstructions to continuation of the current correlator. In this work we supplement their observation with a new dispersive proposal for analytic continuation of the correlator and, assuming polynomial boundedness, derive subtracted dispersion relations relating spacelike and timelike cross sections. We introduce a new factorized function that quantifies the obstruction to crossing and compute its hard kernel at lowest order. The resulting identity connects distribution functions in deep inelastic scattering to fragmentation functions in annihilation.

Germany

Aniruddha Venkata

Spacelike and timelike structure functions: a dispersive crossing relation

Using the string/field theory correspondence as a tool, we study the dependence of the Hagedorn temperature of strongly coupled, planar gauge theories on angular velocities and chemical potentials for U(1) global currents. Our results are obtained from an interplay of world-sheet semiclassical quantization methods and target space low energy effective ones. The Hagedorn temperature is given as an expansion in the inverse (large) ’t Hooft coupling limit. Working to quadratic order in the fluctuations, the world-sheet analysis provides the leading, the next-to-leading and part of the next-to-next-to leading order terms. In particular, it captures the NNLO log 2 terms which are due to the contributions of non-zero modes to the zero-point energy. These modes are not accounted for by the effective approach, within which they have to be included by hand using suitable educated guesses. On the other hand, the effective methods allow to compute in a relatively easy way the missing NNLO pieces (and even further subleading corrections), which could be accounted for from the world-sheet approach only working at quartic (or higher) order in the fluctuations. We present general results and several examples in various dimensions, including both confining models and conformal field theories on spheres (such as $$ \mathcal{N} $$ = 4 SYM and ABJM) dual to string theories on global AdS spaces.

Italy

Francesco Bigazzi

Tommaso Canneti

Federico Castellani

Aldo Cotrone

Hagedorn temperature from holography: rotating and charged systems

The QED scattering amplitude in a chiral medium characterized by a constant chiral chemical potential $\textit{μ}$ and chiral magnetic conductivity $\textit{b}$ is analyzed. We show the emergence of the resonant behavior in 1 → 2, 2 → 2, and 2 → 3 processes. We compute the rates of paradigm 1 → 2 processes that determine the widths of quasi-stationary fermion and photon states in the medium. We elucidate the origin of these resonances, the conditions of their emergence, and the physical principles of their regularization.

United States

Jonathan Kroth

Kirill Tuchin

Scattering amplitudes and resonant processes in QED with chiral chemical potential and chiral magnetic conductivity

We compare standard fixed-order NLO QCD predictions for the full off-shell $$pp\to {e}^{+}{\nu}_{e}{\mu }^{-}{\overline{\nu }}_{\mu }{\tau }^{+}{\nu}_{\tau }b\overline{b }\left(j\right)+X$$ processes in the multi-lepton decay channel with the results obtained using the M NLO approach. The M NLO method, now also implemented in the H -NLO framework, provides a dynamic determination of the renormalization and factorization scale settings by identifying the most likely branching histories of the additional jets through an inverse $\textit{k}$ -clustering algorithm. The inclusion of Sudakov form factors accounts for the large logarithms that arise in the presence of widely separated scales. We perform a dedicated comparison of the two approaches at both the integrated and differential (fiducial) cross-section levels for the LHC Run II energy of $$\sqrt{s}=13$$ TeV. Finally, we present the merging of the full off-shell predictions for $$pp\to {e}^{+}{\nu}_{e}{\mu }^{-}{\overline{\nu }}_{\mu }{\tau }^{+}{\nu}_{\tau }b\overline{b }+X$$ , $$pp\to {e}^{+}{\nu}_{e}{\mu }^{-}{\overline{\nu }}_{\mu }{\tau }^{+}{\nu}_{\tau }b\overline{b }j+X$$ and $$pp\to {e}^{+}{\nu}_{e}{\mu }^{-}{\overline{\nu }}_{\mu }{\tau }^{+}{\nu}_{\tau }b\overline{b }jj$$ , with the aim of improving the description of the underlying $$pp\to {e}^{+}{\nu}_{e}{\mu }^{-}{\overline{\nu }}_{\mu }{\tau }^{+}{\nu}_{\tau }b\overline{b }+X$$ process.

Nikolaos Dimitrakopoulos

Malgorzata Worek

Multi-scale improved predictions for $$pp\to t\overline{t}{W }^{+}+X$$

We study Abelian $\textit{S}$-duality of Maxwell theory on $\textit{A}$-type asymptotically locally Euclidean (ALE) spaces. Unlike on closed four-manifolds, the Maxwell path integral on an ALE space is not naturally a scalar partition function. Rather, it decomposes into theta-function blocks labeled by flat $\textit{U}$ (1) holonomy sectors on the asymptotic lens-space boundary. We interpret these blocks as components of the Hilbert-space boundary state prepared by the ALE path integral. With this interpretation, the apparent failure of ordinary modularity is replaced by vector-valued modular covariance under the action of the modular group. We test this picture explicitly for Eguchi-Hanson space by gluing it to its orientation reversal. The resulting closed four-manifold is diffeomorphic to $\textit{S}$ × $\textit{S}$ , and the natural pairing of the two ALE boundary states reproduces the standard Maxwell partition function on $\textit{S}$ × $\textit{S}$ . We then refine the construction by turning on electric and magnetic 1-form symmetry backgrounds. In their presence, the ALE theta blocks are not ordinary functions, but sections of a line bundle over the Cartan torus associated with the $\textit{A}$ root lattice, reflecting the mixed electric-magnetic 1-form anomaly. We also discuss gauging discrete $\textit{ℤ}$ subgroups of the 1-form symmetries and show that the vector-valued boundary-state structure remains the natural covariant framework after gauging. In this sense, ALE spaces behave as chiral building blocks for four-dimensional Maxwell theory: individual ALE blocks carry sector-resolved boundary data, while gluing pairs these sectors to produce an ordinary closed-manifold partition function, much like the pairing of left- and right-moving conformal blocks in two-dimensional CFT.

United Kingdom

Mohamed Anber

$\textit{S}$-duality, boundary states, and higher-form symmetries on ALE spaces

We study the quantum chaos bound in the photon ring region surrounding black holes. By evaluating the Lyapunov exponent associated with unstable null geodesics in a broad class of generalized Kerr geometries, as well as the temperature induced by a string probe, we show that the quantum chaos bound is exactly saturated on equatorial circular orbits of the photon ring. We confirm our result by deriving the same exponent from out-of-time-order correlators in the near ring region. As a byproduct, we show that the photon ring saturation of the quantum chaos bound implies the saturation of the Bekenstein bound on the rate of information emission from the ringdown phase through the quasinormal modes in the eikonal limit. Our results extend the known correspondence between black hole thermodynamics and chaotic dynamics, highlighting the role of the photon ring as a probe of the fundamental limits on thermalization and information scrambling in black holes.

Taiwan

D. Giataganas

not found

Switzerland

G. Giudice

Greece

A. Kehagias

F. Quevedo

A. Riotto

Black hole photon rings saturate the quantum chaos bound

We identify sectors in large $\textit{N}$ symmetric orbifold CFTs, whose properties are similar to those of closed universes. Starting from tensor product states built out of a finite dimensional low energy subspace of the seed theory, we show that the large $\textit{N}$ Hilbert space decomposes into superselection sectors labeled by occupation number distributions. Before imposing the orbifold gauge constraint, these sectors have exponentially large dimensions, and the maximally entropic sector dominates the ungauged Hilbert space. We argue that this sector exhibits several characteristic features expected of a closed universe Hilbert space: product states become indistinguishable from a mixed state at the level of simple correlators, and the associated operator algebra is naturally a hyperfinite type II von Neumann algebra. We then impose the $\textit{S}$ gauge constraint. The large gauge redundancy drastically reduces the number of independent states. In particular, in the large $\textit{N}$ limit, the dimension of the physical Hilbert space grows only polynomially with $\textit{N}$. Consequently, each superselection sector after imposing the constraint is one dimensional in this limit. This is qualitatively similar to the behavior suggested by gravitational path integral calculations with wormholes. Within this proposed closed universe interpretation, we show why, in this setup, the Hartle-Hawking type semiclassical approximation for the dominant closed universe fails to reproduce the CFT results. Nevertheless, the dominant saddle point approximation for gravitational path integral calculation may be reconstructed once the CFT degrees of freedom are coupled to external observer degrees of freedom.

Japan

Akihiro Miyata

Keigo Horikoshi

Hiromasa Tajima

Tomonori Ugajin

Emergent closed universes in symmetric orbifold CFTs

We regard the weak isospin of the Higgs doublet as a qubit and classify the entanglement measures for the Higgs scattering in the Standard Model Effective Field Theories (SMEFT) and their Ultra-Violet complete models. We consider Higgs scattering in the unbroken phase of electroweak symmetry. Treating the final state as a momentum-isospin bipartite system, we obtain von Neumann and linear entropies to quantify momentum-isospin correlation. From the momentum reduced state, we calculate the concurrence, which measures the entanglement between the two isospins. Both quantities are set by the isospin singlet and triplet scattering amplitudes, and hence by the Wilson coefficients of the dimension-6 and dimension-8 Higgs operators. We find that the von Neumann entropy grows as a function of the total energy in SMEFT as compared to the SM case, but it undergoes a cancellation in the medium energy below the cut-off scale due to the interference effects between the dimension-4 and dimension-8 operators, in particular, when the effective interactions stem dominantly from a massive graviton. Assuming the dominance of dimension-8 operators, we find the conditions for entanglement suppression/generation in the forward or backward scatterings or across all the kinematics. We also show the correlations between the entanglement suppression and the positivity bounds in the forward limit.

South Korea

Hyun Lee

Rojalin Padhan

Higgs scattering and entanglement in SMEFT

<p>Experimental measurements of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> decays to octet baryon pairs reveal a negative-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Σ</mi><mover accent="true"><mi mathvariant="normal">Σ</mi><mo stretchy="false">¯</mo></mover></math> puzzle in the angular distributions, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>α</mi><mi mathvariant="normal">Σ</mi><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></msubsup><mo>&lt;</mo><mn>0</mn></math>, whereas the other measured <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> octet channels and the corresponding <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> channels have positive angular parameters. We show that an <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>SU</mi><mo stretchy="false">(</mo><mn>3</mn><msub><mo stretchy="false">)</mo><mi>F</mi></msub></math>-exact singlet description is strongly disfavored in a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>χ</mi><mn>2</mn></msup></math> fit, giving <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>χ</mi><mn>2</mn></msup><mo>≃</mo><msup><mn>10</mn><mn>5</mn></msup></math>. By contrast, a reduced scenario in which a common final-state interaction mixes the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">S</mi></math>- and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">D</mi></math>-wave amplitudes gives <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>χ</mi><mn>2</mn></msup><mo>=</mo><mn>4.21</mn></math> for the 22 isospin-reduced inputs and two nominal degrees of freedom. We find that the negative-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Σ</mi><mover accent="true"><mi mathvariant="normal">Σ</mi><mo stretchy="false">¯</mo></mover></math> puzzle can be reproduced with direct-production <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>SU</mi><mo stretchy="false">(</mo><mn>3</mn><msub><mo stretchy="false">)</mo><mi>F</mi></msub></math> breaking at the 40% level. This is larger than the conventional quark-mass expectation of about 30%, but numerically smaller than the order-one channel variation suggested by the experimental data. The sizable observable effect is amplified by <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>SU</mi><mo stretchy="false">(</mo><mn>3</mn><msub><mo stretchy="false">)</mo><mi>F</mi></msub></math>-breaking rescattering paths involving S–D mixing. These paths feed the much larger D-wave source into the final <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>SU</mi><mo stretchy="false">(</mo><mn>3</mn><msub><mo stretchy="false">)</mo><mi>F</mi></msub></math>-breaking S-wave amplitude. The largest remaining pull comes from the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></mrow><mo stretchy="false">→</mo><mi>N</mi><mover accent="true"><mi>N</mi><mo stretchy="false">¯</mo></mover></math> angular input, motivating a renewed experimental check of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></mrow><mo stretchy="false">→</mo><mi>n</mi><mover accent="true"><mi>n</mi><mo stretchy="false">¯</mo></mover></math>.</p>

China

Chao-Qiang Geng

Xiang-Nan Jin

Chia-Wei Liu

Negative-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Σ</mi><mover accent="true"><mi mathvariant="normal">Σ</mi><mo stretchy="false">¯</mo></mover></math> angular-parameter puzzle in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> decays

<p>In order to meet the high-precision measurement of the current baryon spectroscopy, for the first time, we rigorously analyze the spin-dependent interactions and the fine structure of the negative-parity singly heavy baryons in the relativized quark model, which was previously unfeasible in the three-quark system. This gains access to the exploration of the strong interactions dominated by the nonperturbative QCD, and reveals how the various forms of strong interactions in a baryon compete with each other, affect the evolution of the energy levels, cause the energy level splitting, and contribute to the mixing effect responsible for the formation of the fine structures. It is shown that the rigorous calculation can nicely reproduce the data; the averaged deviation between the calculated and experimental energy levels is less than 5 MeV for the negative-parity singly heavy baryons. This confirms the reliability of the calculation and also helps make reasonable assignments for the observed negative-parity baryons. The large amount of data obtained by the rigorous calculations contains a wealth of interaction information and is helpful for both of the theoretical and experimental studies. The key to the rigorous calculation in this work is the proposal of a new method, namely the two-step Gaussian expansion method. This new method not only overcomes the long-standing unresolved problem in the relativized quark model, but also provides an effective approach for the high-precision calculation of other few-body systems such as the compact tetraquarks and pentaquarks, especially for the treatment of spin-orbit interactions and tensor interactions which actually appear ubiquitously in all of quantum many-body systems.</p>

Zhen-Yu Li

Guo-Liang Yu

Zhi-Gang Wang

Jian-Zhong Gu

Spin-dependent interactions and fine structure in negative-parity singly heavy baryons