高能暂现源 · 每日文献综述

Pulsar timing arrays (PTAs) observations will detect gravitational waves (GWs) from the early inspiral phase of supermassive black hole binaries (SMBHBs) with orbital periods of weeks to years. Current PTA analyses generally assume circular binaries; however, dynamical interactions with the surrounding environment can prevent complete circularization, allowing SMBHBs to retain appreciable eccentricities. In this work, we present a gravitational waveform model for eccentric binaries based on the effective-one-body (EOB) formalism, designed for continuous GW searches in PTA data. The model is accurate up to the second post-Newtonian (2PN) order for the conservative dynamics and up to postleading order for the radiation-reaction terms. We provide both a numerically precise and a computationally efficient approximate implementation and evaluate the latter's accuracy against the full model over a broad range of eccentricities and initial orbital frequencies. Our results show that a substantial region of the parameter space exhibits pronounced orbital evolution, much stronger than in the circular case. We demonstrate the rich harmonic structure of timing residuals induced by eccentric GWs. Properly characterizing eccentric binaries is an essential step toward detecting GWs in PTA data and interpreting the results, ultimately improving our understanding of the supermassive black hole population in the local Universe.

We investigate a one loop radiative neutrino mass model, where the loop particles, notably a singlet fermion (χ), a doublet fermion (Ψ) and three generations of singlet scalars (ϕ<SUB>i</SUB>, i = {1, 2, 3}) are assumed to be odd under an additional <inline-formula><mml:math><mml:msub><mml:mi>Z</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math></inline-formula>-symmetry. In this setup, the singlet fermion mixes with the neutral component of the doublet to give rise singlet-doublet Majorana dark matter. The addition of <inline-formula><mml:math><mml:msub><mml:mi>Z</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math></inline-formula> odd scalars in the model provides rich phenomenological implications. We find that the quartic interaction terms between the SM Higgs and ϕ<SUB>i</SUB>s play a significant role in modifying the scalar potential to have a first-order phase transition (FOPT) leading to observable gravitational wave (GW) spectra. We also examine the non-trivial role played by the singlet-doublet fermion DM and the scalars in loop-induced neutrino mass, (g ─ 2)<SUB>μ</SUB>, and lepton flavor violation. We find that the model is predictive due to the combined constraints and can be verified at different terrestrial experiments.