Journal of High Energy Physics最新文献

Regge poles connect the analytic structure of scattering amplitudes, analytically continued in angular momentum, to their high-energy limit in momentum space. Dual models are expected to have only Regge poles as singularities in angular momentum space, and string theory suggests there should be an infinite number of them. In this study, we investigate the number of Regge trajectories these models may have. We prove, based solely on crossing symmetry and unitarity, that meromorphic amplitudes, with or without subtractions, cannot produce a reggeizing amplitude if they contain any finite number of Regge trajectories, and show that this excludes the existence of such amplitudes altogether. Additionally, we develop and apply a linear programming dual bootstrap method to exclude these amplitudes directly in momentum space.

We revisit the large N two-matrix model with tr[A, B]² interaction and quartic potentials by the analytic trajectory bootstrap, where A and B represent the two matrices. In the large N limit, we can focus on the single trace moments associated with the words composed of the letters A and B. Analytic continuations in the lengths of the words and subwords lead to analytic trajectories of single trace moments and intriguing intersections of different trajectories. Inspired by the one-cut solutions of one-matrix models, we propose a simple ansatz for the singularity structure of the two-matrix generating functions and the corresponding single trace moments. Together with the self-consistent constraints from the loop equations, we determine the free parameters in the ansatz and obtain highly accurate solutions for the two-matrix model at a low computational cost. For a given length cutoff L_max, our results are within and more accurate than the positivity bounds from the relaxation method, such as about 6-digit accuracy for L_max = 18. The convergence pattern suggests that we achieve about 8-digit accuracy for L_max = 22. As the singularity structure is closely related to the eigenvalue distributions, we further present the results for various types of eigenvalue densities. In the end, we study the symmetry breaking solutions using more complicated ansatzes.

We derive a systematic perturbative expansion for the finite-volume energy spectrum of the non-linear O(N) σ-model in the δ-regime. The violation of the power-counting rules that emerges after the separation of the fast and slow modes is dealt with to all orders by use of the threshold expansion. The known result for the rest-frame energy spectrum up-to-and-including next-to-next-to-leading order is reproduced.

Pair-creation of charged particles in a strong gauge-field background — the renowned Schwinger effect — can strongly alter the efficiency of gauge-field production during axion inflation. It is therefore crucial to have a clear understanding and proper description of this phenomenon to obtain reliable predictions for the physical observables in this model. In the present work, we revisit the problem of Schwinger pair production during axion inflation in the presence of both electric and magnetic fields and improve on the state of the art in two ways: (i) taking into account that the electric- and magnetic-field three-vectors are in general not collinear, we derive the vector decomposition of the Schwinger-induced current in terms of these fields and determine the corresponding effective electric and magnetic conductivities; (ii) by identifying the physical momentum scale associated with the pair-creation process, we incorporate Schwinger damping of the gauge field in a scale-dependent fashion in the relevant equations of motion. Implementing this new description in the framework of the gradient-expansion formalism, we obtain numerical results in a benchmark scenario of axion inflation and perform a comprehensive comparison with earlier results in the literature. In some cases, the resulting energy densities of the produced gauge fields differ from the old results by more than one order of magnitude, which reflects the importance of taking the new effects into account.

In this paper, we explore the imaginary part of the timelike entanglement entropy. In the context of field theory, it is more appropriate to obtain the timelike entanglement entropy through the Wick rotation of the twist operators. It is found that, in certain special cases, the imaginary part of the timelike entanglement entropy is related to the commutator of the twist operator and its first-order temporal derivative. To evaluate these commutators, we employ the operator product expansion of the twist operators, revealing that the commutator is generally universal across most scenarios. However, in more general cases, the imaginary part of the timelike entanglement entropy proves to be more complex. We compute the commutator of the twist operators along with its higher-order temporal derivatives. Utilizing these results, we derive a modified formula for the imaginary part of the timelike entanglement entropy. Furthermore, we extend this formula to the case of strip subregion in higher dimensions. Our analysis shows that for the strip geometry, the imaginary part of the timelike entanglement entropy is solely related to the commutators of the twist operator and its first-order temporal derivative. The findings presented in this paper provide valuable insights into the imaginary part of timelike entanglement entropy and its physical significance.

In this paper we construct CFT states describing a putative holographic dual to local excitations in the three-dimensional de Sitter space (dS), called the bulk local states. We find that the conjugation operation in dS₃/CFT₂ is notably different from that in AdS₃/CFT₂. This requires us to combine two bulk local states constructed out of different primary states in a CPT-invariant way. This analysis explains why Green’s functions in the dS Euclidean vacuum cannot simply be obtained from the Wick rotation of those in AdS. We also argue that this characteristic feature explains the emergence of a time coordinate from the dual Euclidean CFT. We show that the information metric for the quantum estimation of bulk coordinate values replicates the de Sitter space metric.

While topologically stable cosmic strings are disfavoured by the recent observation of nHz stochastic gravitational waves (GW) by Pulsar Timing Arrays (PTA), e.g., NANOGrav, cosmic metastable strings and superstrings are not. However, because the gravitational waves from all classes of strings generally span a wide range of frequencies, they contradict LIGO’s non-observation of stochastic gravitational waves at the f ~ 25 Hz band for a substantial string-parameter space favoured by the PTA data. Suppose ultralight primordial black holes (M_BH < 10⁹ g) existed in the early universe. In this case, they reduce the amplitude of the GWs at higher frequencies by providing an early matter-dominated phase, alleviating the tension between LIGO observation and PTA data. We show that the recent PTA data complemented by future LIGO-Virgo-KAGRA (LVK) runs plus detectors such as LISA and ET would be able to dapple the properties and further search strategies of such ultralight primordial black holes which are otherwise fairly elusive as they evaporate in the early universe by Hawking radiation.

Flow-based architectures have recently proved to be an efficient tool for numerical simulations of Effective String Theories regularized on the lattice that otherwise cannot be efficiently sampled by standard Monte Carlo methods. In this work we use Stochastic Normalizing Flows, a state-of-the-art deep learning architecture based on non-equilibrium Monte Carlo simulations, to study different effective string models. After testing the reliability of this approach through a comparison with exact results for the Nambu-Gotō model, we discuss results on observables that are challenging to study analytically, such as the width of the string and the shape of the flux density. Furthermore, we perform a novel numerical study of Effective String Theories with terms beyond the Nambu-Gotō action, including a broader discussion on their significance for lattice gauge theories. The combination of these findings enables a quantitative description of the fine details of the confinement mechanism in different lattice gauge theories. The results presented in this work establish the reliability and feasibility of flow-based samplers for Effective String Theories and pave the way for future applications on more complex models.

The thermodynamic limits of the XYZ spin chain with periodic or twisted boundary conditions are studied. By using the technique of characterizing the eigenvalue of the transfer matrix by the T − Q relation and by the zeros of the associated polynomial, we obtain the constraints of the Bethe roots and the zeros for the eigenvalues. With the help of structure of Bethe roots, we obtain the distribution patterns of zeros. Based on them, the physical quantities such as the surface energy and excitation energy are calculated. We find that both of them depend on the parity of sites number due to the topological long-range Neel order on the Mobius manifold in the spin space. We also check our results with those obtaining by the density matrix renormalization group. The method provided in this paper can be applied to study the thermodynamic properties at the thermal equilibrium state with finite temperature.

The Izergin-Korepin model is an integrable model with the simplest twisted quantum affine algebra U_q(( {A}_2^{(2)} )) symmetry. Applying the t-W method, we derive the homogeneous zeroes Bethe ansatz equations and the corresponding zeroes patterns of the Izergin-Korepin model with generic integrable boundaries. Based on these results, we analytically compute the surface energies and boundary excitations in different regimes of boundary parameters of the model. It is shown that in some regimes, correlation effect appears between two boundary fields.