The couplings of axionlike particles (ALPs) to Standard Model fermions are proportional to the fermion masses, making the interaction with the top quark particularly significant. In this study, we consider an ALP that is a mixture of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-even and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-odd components, thereby introducing <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation. This <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation, in turn, gives rise to electric dipole moments (EDMs) of quarks and leptons, as well as chromoelectric dipole moments (CEDMs) of quarks. We compute the one-loop and two-loop contributions to the top quark CEDM induced by the ALP. In our calculation, we treat the external gluon as off shell with momentum <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>q</mi><mn>2</mn></msup><mo>≠</mo><mn>0</mn></math>, derive the analytical results, and finally evaluate the top quark CEDM at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>q</mi><mn>2</mn></msup><mo>=</mo><msubsup><mi>m</mi><mi>t</mi><mn>2</mn></msubsup></math>, corresponding to the top quark pole mass. This value is relevant for subsequent calculations of the EDMs of the neutron and mercury. By applying current experimental bounds on EDMs and CEDMs, we derive constraints on the ALP-top quark coupling, with the strongest limit coming from the neutron EDM.

China

Subhadip Bisal

Constraining ALP-top interaction from the chromoelectric dipole moment of the top quark

We construct a new family of quantum chaotic models by combining multiple copies of integrable commuting SYK models. As each copy of the commuting SYK model does not commute with others, this construction breaks the integrability of each commuting SYK and the family of models demonstrates the emergence of quantum chaos. We study the spectrum of this model analytically in the double-scaled limit. As the number of copies tends to infinity, the spectrum becomes compact and equivalent to the regular SYK model. For finite <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math> copies, the spectrum is close to the regular SYK model in UV but has an exponential tail <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mrow><mi>E</mi><mo>/</mo><msub><mi>T</mi><mi>c</mi></msub></mrow></msup></math> in the IR. We identify the reciprocal of the exponent in the tail as a critical temperature <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>c</mi></msub></math>, above which the model should be quantum chaotic. <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>c</mi></msub></math> monotonically decreases as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math> increases, which expands the chaotic regime over the nonchaotic regime. We propose the existence of a new phase around <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>c</mi></msub></math>, and the dynamics should be very different in two phases. We further carry out numeric analysis at finite <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math>, which supports our proposal. Given any finite dimensional local Hamiltonian, by decomposing it into <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math> groups, in which all terms in one group commute with each other but terms from different groups may not, our analysis can give an estimate of the critical temperature for quantum chaos based on the decomposition. We also comment on the implication of the critical temperature to future quantum simulations of quantum chaos and quantum gravity.

United States

Ping Gao

Han Lin

Cheng Peng

Quantum chaos from multiple copies of integrable commuting SYK models

While charged lepton-flavor-violating tau decays to strange mesons provide powerful probes of the underlying <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi><mo stretchy="false">→</mo><mo>ℓ</mo><mi>d</mi><mover accent="true"><mi>s</mi><mo stretchy="false">¯</mo></mover></math> transition, the corresponding decay modes involving hyperons are kinematically forbidden. To address this gap, we propose the quasielastic scattering processes <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>−</mo></msup><mi>N</mi><mo stretchy="false">→</mo><msup><mi>τ</mi><mo>−</mo></msup><mi>Y</mi></math>. Within a general low-energy effective Lagrangian, we perform a comprehensive analysis of the final-state polarizations of both the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> lepton and the hyperon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi></math>, systematically addressing the theoretical uncertainty driven by the model dependence of form factors. Our analysis demonstrates that while this uncertainty leads to large variations in predicted rates, the polarization observables can potentially distinguish between the form factor models, and help to determine the chiral nature of the vectorial new physics interaction. Finally, we forecast the event rates for future facilities, revealing a strong dependence on the form factor models, with predicted yields ranging from potentially observable levels to rates far below current detection thresholds.

Xin-Shuai Yan

Zhen-Qing Hu

Qin Chang

Ya-Dong Yang

Polarization probes of new physics in lepton-flavor-violating hyperon production from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>−</mo></msup><mi>N</mi><mo stretchy="false">→</mo><msup><mi>τ</mi><mo>−</mo></msup><mi>Y</mi></math> scattering

In previous work [D. Giusti, et al., Methods for high-precision determinations of radiative-leptonic decay form factors using lattice QCD, <a href="http://dx.doi.org/10.1103/PhysRevD.107.074507">Phys. Rev. D 107, 074507 (2023)</a>], we showed that form factors for radiative leptonic decays of pseudoscalar mesons can be determined efficiently and with high precision from lattice QCD using the “three-dimensional (3D) method,” in which three-point functions are computed for all values of the current insertion time and the time integral is performed at the data-analysis stage. Here, we demonstrate another benefit of the 3D method: the form factors can be extracted for any number of nonzero photon virtualities from the same three-point functions at no extra cost. We present results for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>D</mi><mi>s</mi></msub><mo stretchy="false">→</mo><mo>ℓ</mo><mi>ν</mi><msup><mi>γ</mi><mo>*</mo></msup></math> vector form factor as a function of photon energy and photon virtuality, for both positive and negative virtuality, for a single ensemble with 340 MeV pion mass and 0.11 fm lattice spacing. In our analysis, we separately consider the two different time orderings and the different quark flavors in the electromagnetic current. We discuss in detail the behavior of the unwanted exponentials contributing to the three-point functions, as well as the choice of fit models and fit ranges used to remove them for various values of the virtuality. While positive photon virtuality is relevant for decays to multiple charged leptons, negative photon virtuality suppresses soft contributions and is of interest in QCD-factorization studies of the form factors.

Germany

Davide Giusti

Christopher F. Kane

Christoph Lehner

Stefan Meinel

Amarjit Soni

Efficient lattice QCD computation of radiative-leptonic-decay form factors at multiple positive and negative photon virtualities

Seeking mass patterns is a key to decoding the unknown flavor puzzles in particle physics. Inspired by quark hierarchical masses, the mass matrix can universally be factorized into a family-diagonal phase matrix $$K_L^q$$ and a real symmetric matrix $$M_N^q$$ characterized by only two parameters. The factorized structure provides model-independent rules to the mass matrix. We demonstrate that the large $$\delta _{CP}$$ naturally arises from the degeneracy of the first two quark families in the mass hierarchy limit. As an application, the flat pattern with elements close to unity in the matrix is checked by fitting quark masses and the CKM mixing. It achieves a precise description of flavor structure with minimal parameters.

Ying Zhang

Mass matrix rules and the flat pattern of quarks

In this Letter we propose an interpretation of the Hubble tension as an effect of the scale-running of cosmological parameters and fundamental constants, as the Newton’s constant $\textit{G}$ and the cosmological constant $$\Lambda $$ . Namely, the tension between $$H_0$$ measurements by CMB and Supernovae observations would be a consequence of the fact that the value of $$H_0$$ depends (due to the running of $\textit{G}$ and $$\Lambda $$ ) on the scale at which it is measured. Indeed, the two different values of the Hubble parameter $\textit{today}$ correspond to the two different cosmological scales at which Supernovae and CMB measurements probe our universe. We discuss some possible theoretical scenarios in which the running of $\textit{G}$ and $$\Lambda $$ can occur. We stress that one should interpret such a running as a scale-dependence of the cosmological parameters and fundamental constants at the same time rather than a time dependence, as it is usually considered in the literature.

Italy

Fabio Briscese

The Hubble tension as an effect of the renormalization of fundamental constants and cosmological parameters

Analyses of astrophysical observations, such as quasiperiodic oscillations (QPOs), combined with theoretical studies, help to understand the deeper properties of black hole spacetime and obtain parameters of black holes and alternative gravity theories. In this study, we investigate the dynamics of charged particles orbiting magnetized black holes within the Bertotti–Robinson (BR) geometry, also known as the electromagnetic universe (EU). We study the circular motion and oscillations of charged particles around a black hole in the presence of a magnetic field, focusing on their applications to QPOs. First, we obtain solutions for the Maxwell equations for orthonormal components of magnetic fields around the black holes in radial and angular directions and analyze the dependence on the EU field and magnetic interactions. The effective potential, specific angular momentum, energy, and innermost stable circular orbits (ISCOs) of charged particles are analyzed to demonstrate how the black hole spacetime, in conjunction with magnetic interaction and EU parameters, affects particle dynamics. Then, we calculate the Keplerian, radial, and vertical epicyclic frequencies, providing insight into the orbital and oscillatory behavior of particles near the black holes. Furthermore, we investigate twin-peak QPOs using the relativistic precession (RP) model and compare the main results with those of the standard Schwarzschild limit. Finally, we employ Monte Carlo Markov Chain (MCMC) simulations to obtain constraint values for black hole mass, the EU, and magnetic interaction parameters, using QPO frequency data observed in microquasars (as an example, XTE J1550-564, GRO J1655-40, GRS 1915+105) and galactic centers (in cases of M82 and Milky Way). Our findings may provide valuable insights into understanding the combined effects of RB spacetime and electromagnetic interactions around black holes on astrophysical observations of QPOs and testing gravity theories in a strong gravity regime.

Uzbekistan

Abubakir Shermatov

Javlon Rayimbaev

Czechia

Bekir Lütfüolu

Ahmadjon Abdujabbarov

Sabirov Sardor

Inomjon Ibragimov

Murodbek Vapayev

Bahrom Kuyliev

QPOs analyses and circular orbits of charged particles around magnetized black holes in Bertotti–Robinson geometry

Towers of electrically and magnetically charged states in quantum gravity often exhibit two important properties. First, the ratio of the mass (or tension) of electrically charged states to magnetically charged states is of order $\textit{e}$ /(4$\textit{π}$), which we refer to as “co-scaling.” Second, in theories of multiple gauge fields, the towers of states that exhibit co-scaling have charges that point in approximately the same direction in charge space as measured by the gauge kinetic matrix, which we refer to as “alignment.” After motivating these ideas with some heuristic arguments, we examine the spectrum of BPS states in the 5d supergravity landscape arising from M-theory on a Calabi-Yau threefold. In this setting, every tower of magnetically charged strings is paired with a corresponding tower of electrically charged particles that exhibits co-scaling and rapid alignment. In particular, this motivates a sharp mathematical characterization of the magnetic infinity cone in Calabi-Yau geometry. We propose a universal conjecture about quantum gravity: towers of charged states which, in some limit in moduli space, have maximally divergent charge-to-mass ratios always have corresponding magnetic partner states exhibiting co-scaling and alignment. Co-scaling is not a general feature of extremal black hole solutions in theories of gauge fields and scalars, suggesting that it is a principle of UV complete quantum gravity. We briefly remark on possible phenomenological applications, including to axion physics.

Matthew Reece

United Kingdom

Tom Rudelius

Christopher Tudball

Co-scaling and alignment of electric and magnetic towers

We consider confining Hidden Valley/Dark Sector theories containing many dark quark flavors. These theories are in the “conformal window”: they reach an infrared fixed point when their quarks are massless, and have unfamiliar confinement when the quark masses are non-zero but small. Their jets of hidden hadrons may be quite different from those familiar from QCD, but their details cannot currently be simulated even qualitatively. This is partly due to the use of approximations to the two-loop running coupling in existing event generators’ parton showers, which are not broadly applicable across the conformal window. We argue that the exact two-loop running coupling, and a corresponding Sudakov factor employing that coupling, must be implemented in simulation packages in order to allow phenomenological studies of these theories.

Austria

Suchita Kulkarni

Joshua Lockyer

Matthew Strassler

On the simulation of hidden parton showers in the conformal window

This work delves into the phenomenology of electronic inclusive decays of $\textit{D}$ mesons, encompassing $$D^0, D^+, D^+_s\rightarrow Xe^{+}\nu $$ . The theoretical formulas for the decay widths and electron energy moments of these decays are presented as expansions with powers of $$\alpha _s$$ and $$\Lambda _\textrm{QCD}/m_c$$ . Remarkably, the expansion exhibits excellent convergence properties when we choose the 1S mass scheme for charm. The formulas are subsequently fitted to experimental data, and the $\textit{D}$ meson matrix elements of operators in the heavy quark effective theory are hence determined by data for the first time, including $$\begin{aligned} \mu ^2_\pi (D^{0,+})&= (0.08\pm 0.05) \, \textrm{GeV}^2,\nonumber \\ \mu ^2_\pi (D^{+}_s)&= (0.10\pm 0.07) \, \textrm{GeV}^2,\nonumber \\ \mu ^2_G(D^{0,+})&= (0.33\pm 0.03) \,\textrm{GeV}^2, \nonumber \\ \mu ^2_G(D^{+}_s)&= (0.44\pm 0.06) \,\textrm{GeV}^2, \nonumber \\ \rho _D^3(D^{0,+})&= (-0.003\pm 0.002) \,\textrm{GeV}^3, \nonumber \\ \rho _D^3(D^{+}_s)&= (-0.004\pm 0.002) \,\textrm{GeV}^3, \nonumber \\ \rho _{LS}^3(D^{0,+})&= (0.004\pm 0.002) \,\textrm{GeV}^3, \nonumber \\ \rho _{LS}^3(D^{+}_s)&= (0.005\pm 0.002) \,\textrm{GeV}^3 , \end{aligned}$$ These determined parameters will play a crucial role as inputs in various physical quantities, including $\textit{D}$ meson lifetimes.

Kang-Kang Shao

Chun Huang

Qin Qin

Data determination of HQET parameters in inclusive charm decays