A quantum theory of asymptotically flat spacetimes is presented using the solutions of the null surface formulation (NSF) field equations in a perturbative scheme. Free-field commutation relations are given for the null free data of NSF at future or past null infinity, and the main variables of NSF are then used to define the interior points of the spacetime as labels and the metric of the spacetime as a derived quantum operator. A nontrivial scattering of gravitons is given.

Argentina

Carlos N. Kozameh

Lautaro Zapata-Altuna

Quantum theory of asymptotically flat spacetimes

In this Letter, we examine the impact of QCD phase transitions on the quark spin fluctuations and correlations. We propose the quark-antiquark correlation, which relates to the vector meson spin alignment and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">Λ</mi><mo>−</mo><mover accent="true"><mrow><mi mathvariant="normal">Λ</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow></math> correlation, and can be used as a novel probe of the critical end point (CEP) in the QCD phase diagram. Using the Nambu-Jona-Lanisio model, we qualitatively study the properties of quark-antiquark spin correlations. Our findings reveal a peak structure near the CEP of the chiral phase transition, which may serve as an experimental signature of the CEP and account for the non-monotonic behavior of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi></math> meson alignment at low collision energies observed recently in experiments.

China

Hao-Lei Chen

Wei-jie Fu

Xu-Guang Huang

Guo-Liang Ma

Fluctuations and Correlations of Quark Spin in Hot and Dense QCD Matter

We determine the value of the strong coupling <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>α</mi></mrow><mrow><mi mathvariant="normal">s</mi></mrow></msub></mrow></math> and study its running over a wide range of scales as probed by the dijet production process at hadron colliders, based on a next-to-next-to-leading-order QCD analysis of LHC dijet data. From a large subset of these data a value of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><msub><mrow><mi>α</mi></mrow><mrow><mi mathvariant="normal">s</mi></mrow></msub><mo stretchy="false">(</mo><msub><mrow><mi>m</mi></mrow><mrow><mi mathvariant="normal">Z</mi></mrow></msub><mo stretchy="false">)</mo></mrow><mo>=</mo><mn>0.1178</mn><mo>±</mo><mn>0.0022</mn></mrow></math> is obtained for the strong coupling at the scale of the Z-boson mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi mathvariant="normal">Z</mi></msub></math>, using the invariant mass of the dijet system to select the scale where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi mathvariant="normal">s</mi></msub></math> is probed. The combination of different datasets enhances the reach and precision of the analysis in the multi-TeV range and allows for the first determination of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>α</mi></mrow><mrow><mi mathvariant="normal">s</mi></mrow></msub></mrow></math> up to scales of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>7</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math>. Complementing the LHC data with dijet cross sections measured at the HERA electron–proton collider, the kinematic range is extended to test the running of the strong coupling toward smaller scales. Our results exhibit excellent agreement with predictions based on the renormalization group equation of QCD, and represent a comprehensive test of the asymptotic behavior of QCD, spanning more than three orders of magnitude in energy scale.

Germany

Switzerland

Fazila Ahmadova

Daniel Britzger

Xuan Chen

Johannes Gäßler

Aude Gehrmann-De Ridder

Thomas Gehrmann

United Kingdom

Nigel Glover

Claire Gwenlan

Gudrun Heinrich

CERN

Alexander Huss

Lucas Kunz

Portugal

João Pires

Klaus Rabbertz

Mark Sutton

Precise Determination of the Strong Coupling Constant from Dijet Cross Sections up to the Multi-TeV Range

We study infrared divergences in quantum electrodynamics using geometric phases and the adiabatic approximation in quantum field theory. In this framework, the asymptotic $\textit{in}$ and $\textit{out}$ states are modified by Berry phases, $$ {e}^{i\Delta {\alpha}_{\textrm{in}}} $$ and $$ {e}^{i\Delta {\alpha}_{\textrm{out}}} $$ , which encode the infrared structure non-perturbatively and regulate soft-photon divergences.

Chile

J. Gamboa

Topology and the infrared structure of quantum electrodynamics

Certain models of inert multiplets allow for semi-annihilation processes, in which two dark matter candidates annihilate to a dark matter particle and a non-dark matter particle. The existence of these processes can alleviate certain constraints and substantially modify the indirect detection signal. In this paper, we study current indirect detection constraints on the semi-annihilation of inert scalar multiplets. We show that there exist gauge numbers for which dark matter can be thermally produced and be compatible with indirect detection constraints even for very cuspy galactic dark matter density profiles.

Taiwan

Hugues Beauchesne

Cheng-Wei Chiang

Indirect detection constraints on semi-annihilation of inert scalar multiplets

We study the radiative properties of a spherical and singularity-free black-hole geometry recently proposed in the literature. Contrary to the Schwarzschild spacetime, this geometry is geodesically complete and regular, and, instead of the singularity, it presents a minimal surface that connects a trapped (black-hole) with an antitrapped (white-hole) region. The geometry is characterized by two parameters: the Schwarzschild radius and another parameter that measures the area of the minimal surface. This parameter is related to certain corrections expected in the context of loop quantum gravity to the classical general-relativistic dynamics. We explicitly compute the spectrum of the Hawking radiation and the gray-body factor. Since the gravitational potential is shallower than in Schwarzschild, the emission spectrum turns out to be colder and purer (less gray). From this, we sketch the evaporation history of this geometry and conclude that, under certain assumptions, instead of completely evaporating, the black hole naturally leads to a remnant, which provides a possible resolution to the information-loss issue.

Spain

Asier Alonso-Bardaji

David Brizuela

Marc Schneider

Radiative properties of a nonsingular black hole: Hawking radiation and gray-body factor

The renormalization of a parity-even massless U(1) × U(1) quantum electrodynamics in three space-time dimensions (QED ) is studied by adopting the Bogoliubov-Parasiuk-Hepp-Zimmermann-Lowenstein (BPHZL) renormalization method. The presence of two massless fermions requires the Lowenstein-Zimmermann (LZ) subtraction scheme to renormalize the infrared divergences induced by the ultraviolet subtractions at 1- and 2-loops, moreover due to the model superrenormalizability the ultraviolet divergences are bounded up to 2-loops. Finally, through the BPHZL renormalization method together with the LZ subtraction scheme the ultraviolet and infrared finiteness of the model is proved up to 2-loops and beyond.

Brazil

D. Azevedo

O. Cima

L. Lima

E. Miranda

The BPHZL renormalization of a planar quantum electrodynamics up to 2-loops and beyond

Information scrambling refers to the phenomenon in which local quantum information in a many-body system becomes dispersed throughout the entire system under unitary evolution. It has been extensively studied in closed quantum systems, where it is quantified by operator size growth, revealing deep connections between condensed matter physics, high-energy physics, and quantum information. However, when extending the study of operator size dynamics to open quantum systems, two different definitions of operator size distributions emerge. These definitions are based on different treatments of the bath. In this work, we aim to establish a unified picture for operator size dynamics in open quantum systems, using the solvable Brownian SYK models at generic system size. In particular, we provide the conditions under which the signature of scrambling transition — discovered using one particular definition — appears in operator size dynamics under the other definition. Additionally, we extend previous studies by exploring finite-size effects that are not captured by the scramblon theory. Our results provide a refined understanding of operator size dynamics in open quantum systems.

Haolin Jiang

Pengfei Zhang

Refining the understanding of operator size dynamics in open quantum systems

Motivated by the recent discovery of hidden zeros in particle and string amplitudes, we characterize zeros of individual graph contributions to the cosmological wavefunction of a scalar field theory. We demonstrate that these contributions factorize near these zeros for all tree graphs and provide evidence that this extends to loop graphs as well. We explicitly construct polytopal realizations of the relevant graph associahedra and show that the cosmological zeros have natural geometric and physical interpretations. As a byproduct, we establish an equivalence between the wavefunction coefficients of chain graphs and flat-space Tr($\textit{ϕ}$ ) amplitudes, enabling us to leverage the cosmological zeros to uncover the recently discovered hidden zeros of colored amplitudes.

United States

Shounak De

Shruti Paranjape

Andrzej Pokraka

Marcus Spradlin

Anastasia Volovich

Hidden zeros of the cosmological wavefunction

The Veneziano amplitude describing the tree-level scattering of four open superstrings is expected to be consistent with unitarity in ten spacetime dimensions. While this follows indirectly from the no-ghost theorem, a direct proof at the level of the amplitude itself only exists for $\textit{D}$ ≤ 6. In this note, we close this gap by providing a proof for the partial-wave positivity of the Veneziano amplitude in $\textit{D}$ ≤ 10, derived directly from its representation as the Euler beta function. We also demonstrate that this proof can be modified to show the positivity of a wider family of amplitudes relevant to the $\textit{S}$-matrix bootstrap.

Gareth Mansfield

Positivity of the Veneziano amplitude in ten dimensions