This paper focuses on the Kramers escape rate, offering a dynamic approach to phase transitions in black holes. We examine the free energy landscapes under ‘dark’ and ‘stringy+dark’ influences, assessing the impact of additional parameters on escape rates and transition dynamics during first-order phase transitions from small to large black holes. We analyze the escape rate as a function of black hole radius, noting its increase from zero to a maximum point and decrease back to zero as reactive structures activate. A crucial point is where the direct process (small to large black holes) intersects with the reverse process (large to small black holes), making both equally probable. This point gains significance as the process progresses, indicating the dominance of the reverse process, which helps maintain black hole stability by preventing uncontrolled radial growth.

Iran

Canada

Mohammad Afshar

Saeed Noori Gashti

Mohammad Alipour

Jafar Sadeghi

Kramer’s escape rate and phase transition dynamics in AdS black holes

In this work, we studied the quasinormal modes (QNM) and shadow of a Schwarzschild Black hole (BH) with higher-order metric corrections, in the framework of Infinite Derivative theory of Gravity (IDG). We studied the effects on QNMs and shadow of the BH, which arises from the IDG’s corrections to the BH’s metric. We used 6th order Padé averaged WKB approximation method to study the QNMs of the BH perturbed by a scalar field. We analyze the dependence of the amplitude and damping of QNMs with respect to the free parameters. Next, we studied the time evolution of a scalar field around the BH spacetime. The QNMs have been calculated from the time profile of the evolution. Then we studied the shadow of the BH. The variation of the shadow radius due to inclusion of higher-order corrections was studied and the variation of the shadow radius with respect to the free parameters also studied. Furthermore, the dependence of the shadow radius on the mass of the BH is also studied. Finally, we constrained the free parameters associated with the correction terms using the data from the Keck and VLTI observation, and we obtained some bounds on the parameters.

India

Rupam Borah

Umananda Goswami

Quasinormal modes and shadows of black holes in infinite derivative theory of gravity

We study resonant production of pairs of Standard Model (SM-)like Higgs bosons, in the presence of new neutral Higgs states together with new colored scalars (stops or sbottoms) in loops within the Next-to-Minimal Supersymmetric Standard Model. This is used as a test case to prove that the Large Hadron Collider has sensitivity to a variety of effects stemming from interferences between resonant (heavy) Higgs diagrams and/or among these and nonresonant topologies involving loops of both tops and stops. These effects can alter significantly the naive description of individual <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>s</mi></mrow></math>-channel Breit-Wigner resonances, leading to distortions of the latter, which, on the one hand, may mask their presence but, on the other hand, could enable one to extract features of the underlying new physics scenario. This last aspect is made possible through a decomposition of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>g</mi><mi>g</mi><mo stretchy="false">→</mo><mi>h</mi><mi>h</mi></math> signal process into all its amplitude components, each of which has a well-defined coupling structure. Ultimately, such effects can be traced back to the relevant Feynman diagrams and can enable a detailed interpretation of this process. To illustrate this, we introduce various benchmark points that exhibit potentially observable features during the current and/or upcoming runs of the LHC in one or more of the three customary di-Higgs decay channels: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover><mi>b</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover><msup><mi>τ</mi><mo>+</mo></msup><msup><mi>τ</mi><mo>−</mo></msup></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover><mi>γ</mi><mi>γ</mi></math>.

United Kingdom

Sweden

Stefano Moretti

Italy

Luca Panizzi

Jörgen Sjölin

Harri Waltari

Deconstructing resonant Higgs boson pair production at the LHC: Effects of colored and neutral scalars in the NMSSM test case

The three Standard Model neutrinos can have Majorana mass or strictly Dirac mass, but both scenarios are practically indistinguishable in neutrino oscillation experiments. If they are pseudo-Dirac, however, there will be new mass splittings among the pseudo-Dirac pairs, potentially leaving traces in neutrino oscillation phenomena. In this work, we use flavor ratios of astrophysical neutrinos to discriminate different possible mass spectra of pseudo-Dirac neutrinos. We show that it will be possible to impose robust bounds of order <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>δ</mi><msubsup><mrow><mi>m</mi></mrow><mrow><mn>3</mn></mrow><mrow><mn>2</mn></mrow></msubsup><mo>≲</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>12</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>eV</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> on the new mass squared splitting involving the third pseudo-Dirac mass eigenstates (those with the least electron flavor composition) with the future experiment IceCube-Gen2. The derived sensitivity is robust because it only assumes an extragalactic origin for the astrophysical neutrinos and hierarchical pseudo-Dirac mass spectrum. In case the neutrino sources are known in the future, such bounds can potentially improve by up to five orders of magnitude, reaching <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>δ</mi><msubsup><mi>m</mi><mn>3</mn><mn>2</mn></msubsup><mo>≲</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>17</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mi>eV</mi><mn>2</mn></msup></math>.

Brazil

Chee Sheng Fong

Yago Porto

Constraining the pseudo-Dirac nature of neutrinos using astrophysical neutrino flavor data

We propose a quantum mechanical theory of quantum spaces described by large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> noncommutative geometry as a model for quantum gravity. The model admits a fuzzy sphere as a static solution. Over the fuzzy geometry, the quantum mechanics of the fermions is given by a sum of oscillators with equal frequency. The energy state where exactly half of the Fermi sea is filled contains the maximal amount of degeneracy. This state of the fuzzy sphere obeys the mass-radius relation of a Schwarzschild black hole if the fuzzy sphere is identified with the black hole horizon. Moreover, the set of states in the Fermi sea gives precisely the Bekenstein-Hawking entropy. We thus propose that quantum black holes are described by fuzzy spheres with a half-filled Fermi sea in our model. We also consider a system of two fuzzy spheres by embedding them as blocks in the matrix quantum mechanics. When the distance <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>r</mi></math> between the two fuzzy spheres is small, the total energy of the system can be computed using perturbation theory. We show that, in the leading order of large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> limit, the interaction energy depends on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>−</mo><mi>G</mi><msub><mi>M</mi><mn>1</mn></msub><msub><mi>M</mi><mn>2</mn></msub></math> exactly in the manner as in Newton gravity. To reproduce the correct <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>r</mi></math> dependence in the long range, we expect the inclusion of large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> corrections and quantum effects will be needed.

Taiwan

Chong-Sun Chu

Matrix model proposal for quantum gravity and the quantum mechanics of black holes

We investigate the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ϕ</mi><mrow><mn>2</mn><mi>n</mi></mrow></msup></math> deformations of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">O</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></mrow></math>-symmetric (generalized) free theories with a flat boundary, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>n</mi><mo>≥</mo><mn>2</mn></math> is an integer. The generalized free theories refer to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mo>□</mo><mi>k</mi></msup></math> free scalar theories with a higher derivative kinetic term, which is related to the multicritical generalizations of the Lifshitz type. We assume that the (generalized) free theories and the deformed theories have boundary conformal symmetry and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">O</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></mrow></math> global symmetry. The leading anomalous dimensions of some boundary operators are derived from the bulk multiplet recombination and analyticity constraints. We find that the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ε</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup></math> expansion in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ϕ</mi><mn>6</mn></msup></math>-tricritical version of the special transition extends to other multicritical cases with larger odd integer <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>n</mi></math>, and most of the higher derivative cases involve a noninteger power expansion in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ε</mi></math>. Using the analytic bootstrap, we further verify that the multiplet-recombination results are consistent with boundary crossing symmetry.

China

Yongwei Guo

Wenliang Li

Boundary anomalous dimensions from BCFT: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">O</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></mrow></math>-symmetric <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ϕ</mi><mrow><mn>2</mn><mi>n</mi></mrow></msup></math> theories with a boundary and higher-derivative generalizations

Spain

Daniel Castillo

Lotta Jokiniemi

Pablo Soriano

Javier Menéndez

Corrigendum to “Neutrinoless ββ decay nuclear matrix elements complete up to N 2LO in heavy nuclei&#8221; [Physics Letters B 860 (2025) 139181]

We study SU($\textit{N}$) spin systems that mimic the behavior of particles in $\textit{N}$-dimensional de Sitter space for $\textit{N}$ = 2, 3. Their Hamiltonians describe a dynamical system with hyperbolic fixed points, leading to emergent quasinormal modes at the quantum level. These manifest as quasiparticle peaks in the density of states. For a particle in 2-dimensional de Sitter, we find both principal and complementary series densities of states from a PT-symmetric version of the Lipkin-Meshkov-Glick model, having two hyperbolic fixed points in the classical phase space. We then study different spectral and dynamical properties of this class of models, including level spacing statistics, two-point functions, squared commutators, spectral form factor, Krylov operator and state complexity. We find that, even though the early-time properties of these quantities are governed by the saddle points — thereby in some cases mimicking corresponding properties of chaotic systems, a close look at the late-time behavior reveals the integrable nature of the system.

Japan

Sergio Aguilar-Gutierrez

South Korea

Yichao Fu

Kuntal Pal

United States

Klaas Parmentier

Quasinormal modes and complexity in saddle-dominated SU($\textit{N}$) spin systems

We study the spectrum of scalar primary operators in any two-dimensional conformal field theory. We show that the scalars alone obey a nontrivial crossing equation. This extends previous work that derived a similar equation for Narain conformal field theories. Additionally, we show that at high temperature, the difference between the true scalar partition function and the one predicted from a semiclassical gravity calculation is controlled by: the modular integral of the partition function, the light states of the theory, and an infinite series terms directly related to the nontrivial zeros of the Riemann zeta function. We give several numerical examples and compute their modular integrals.

Nathan Benjamin

Cyuan-Han Chang

A. Fitzpatrick

Tobi Ramella

Properties of scalar partition functions of 2d CFTs

We investigate the scattering amplitudes of massive Kaluza-Klein (KK) states in compactified five-dimensional warped gauge and gravity theories. Focusing on tree-level 2 → 2 processes, we analyze the leading-order amplitudes involving bulk KK matter fields and KK gauge/gravitational Goldstone bosons. By imposing the gauge theory equivalence theorem (GAET) and the gravitational equivalence theorem (GRET) within warped KK theories, we systematically reconstruct the leading-order amplitudes for physical KK gauge bosons and gravitons, thereby circumventing the intricate energy cancellations inherent in physical amplitudes. Within this framework, the correspondence between GAET and GRET arises as a direct manifestation of the leading-order double-copy relation in the high-energy expansion. This connection provides a foundation for extending the BCJ double-copy construction to four-point amplitudes involving bulk KK matter fields, and further generalizes to arbitrary $\textit{N}$-point cases, enabling a systematic derivation of the corresponding gravitational amplitudes with consistent incorporation of KK matter fields at leading order.

Kezhu Guo

Yanfeng Hang

Equivalence theorems and double-copy structure in scattering amplitudes of massive Kaluza-Klein states with matter interactions