21 August 2026

We study leptogenesis via out-of-equilibrium decays of right-handed neutrinos in a parity symmetric extension of the Standard Model with gauge group $SU(3)_c \times SU(2)_L \times SU(2)_R \times U(1)_X$, spontaneously broken to the Standard Model gauge group at a scale $v_R$. We focus on the minimal Higgs realization, in which the strong CP problem is resolved without invoking additional symmetries. In this framework, lepton number is violated through Yukawa interactions, while neutrino masses arise only at higher loop order, a feature that permits the CP-violating quantum corrections to right-handed neutrino decays to be parametrically large. For thermal production of right-handed neutrinos, we find that successful leptogenesis requires $v_R \gtrsim 6\times 10^{12}$ GeV. Non-thermal production, however, relaxes this bound dramatically, requiring only $v_R \gtrsim 10$ TeV, a scale accessible to collider searches for new particles and searches for rare processes.

Since all the Standard Model (SM) parameters have been measured to precision at the percent level or smaller, one would aim to have a framework which describes baryogenesis as precise as possible, where the measured SM parameters are used as inputs. At high temperature before the electroweak symmetry breaking, the SM contains 15 approximate $U(1)$ symmetries with the associated flavor charges. To describe the evolutions of these flavor charges in a flavor-basis-covariant manner such that physical observables are flavor-basis-independent, a total of five density matrices in flavor spaces are required: three for quarks and two for leptons. Taking into account the quantum chromodynamics and electroweak sphaleron interactions together with all the Yukawa interactions, we obtain the complete flavor-covariant Boltzmann equations. By imposing chemical equilibrium in the lepton sector, we further derive a new effective quark-flavor-covariant formalism which can be used when baryogenesis occurs through number asymmetry generation in the quark sector. To verify the consistency of this complete formalism, we first apply it to leptogenesis scenarios, reproducing previous results which utilize the effective lepton-flavor-covariant formalism up to small corrections due to the quark chemical equilibrium approximations used in the latter formalism. Then, for the first time, we apply the complete formalism as well as the effective quark-flavor-covariant formalism to a cloistered baryogenesis scenario where number asymmetries are generated in the quark sector, showcasing the good agreement between the results from the two formalisms. Finally, we release the first generic baryogenesis public code BOLEH (BaryOn and Lepton charge Evolution in the Hot big bang) where all the SM interactions are taken into account.

Recently, the CMS and ATLAS Collaborations reported an enhancement near the production threshold in the invariant-mass distribution of top-antitop pairs. Possible interpretations include a pseudoscalar toponium quasi-bound state and an additional elementary pseudoscalar that coexists or mixes with toponium. Motivated by the latter interpretation, we identify the additional pseudoscalar with the CP-odd Higgs boson of a top-philic Type-III two-Higgs-doublet model (2HDM). This possibility is also interesting from the viewpoint of electroweak baryogenesis: the extended scalar sector can support a strong first-order electroweak phase transition, while the additional top-quark Yukawa interaction can provide a CP-violating source through the bubble-wall background. We therefore investigate whether the same parameter region motivated by the $t\bar{t}$ threshold enhancement can also account for the observed baryon asymmetry of the Universe (BAU). We compare two scenarios with different origins of CP violation. In the explicit CP violation scenario, a complex phase is introduced into the additional top-quark Yukawa coupling $ρ_{tt}$. In the transitional CP violation (TCPV) scenario, a CP-odd field configuration is generated dynamically inside the bubble wall through finite-temperature effects. Within the present one-loop treatment, explicit CP violation remains a scheme-dependent possibility, whereas no viable transitional CP violation branch is identified. In addition, we discuss the physical differences and viability of these two scenarios.

The Jiangmen Underground Neutrino Observatory (JUNO) experiment is a reactor antineutrino detector employing 20 kton of ultra-pure liquid scintillator to determine the neutrino mass ordering and to precisely measure oscillation parameters. The total singles background rate from radioactivity is required to be below 10 Hz in the energy range of 0.7-12 MeV within the fiducial volume for reactor neutrino analysis. The calibration system is designed to characterize the detector energy and position responses, while several of its components are located close to the target and may contribute to the background budget. Therefore, extensive material screening and selection are required to construct a low-background calibration system and to ensure that its contribution remains within the design requirements. In this work, a comprehensive study of the radioactive background induced by the calibration system is presented, including material radioactivity measurements using high-purity germanium detectors and neutron activation analysis techniques, detailed Monte Carlo simulations to evaluate the background, and comparisons with in-situ detector data to validate the predictions. In this data analysis, dedicated spatial selection methods are developed to isolate calibration-related contributions and to suppress the liquid scintillator background. The total radioactivity contribution from the calibration system is estimated to be less than 76 mHz, which satisfies the requirement of 200 mHz (2% of the total background budget). The results from in-situ data are found to be consistent with the expectations based on material assay and simulation within uncertainties. These results demonstrate that the calibration-induced background is well understood, in agreement between data and simulation, and negligible for reactor antineutrino measurements in JUNO.

Let $p, N \geq 5$ be primes such that $N \equiv 1 \bmod p$. We prove modularity theorems at levels $N$ and $N^2$, showing that suitable Eisenstein localizations of the weight-$2$ $p$-adic Hecke algebra at these levels are isomorphic to certain natural quotients of a universal pseudodeformation ring. This universal ring parametrizes pseudorepresentations that are residually Eisenstein, unramified outside $Np$ and finite-flat at $p$, and satisfy appropriate conditions at $N$ depending on the level.

Characterizing isolated points on the modular curve $X_1(N)$ is a key obstruction to classifying all points of a fixed degree. These points do not lie in infinite parameterized families, making them difficult to obtain through geometric constructions. In this paper, we focus on the collection of "isolated $j$-invariants" for $X_1(N)$, which are the values obtained by mapping isolated points to the $j$-line. Prior work of the author in collaboration with Ejder, Liu, Odumodu, and Viray asks whether there are only finitely many isolated $j$-invariants lying in extensions of bounded degree. Here, we explore how this question relates to other uniformity problems in the field and give new finiteness results for isolated $j$-invariants in $\mathbb{Q}$. As an application, we show similar methods give sharpened polynomial bounds on torsion for non-CM elliptic curves having rational $j$-invariant.

We propose a minimal three-family realization of quark--lepton complementarity (QLC) in which the non-trivial correlation matrix is an exactly unitary, rigid deformation of tri-bimaximal mixing. In a canonical TBM convention the deformation is a rotation about the normalized axis $n_{gg}=(2,1,2)^T/3$, with rotation angle fixed by the Cabibbo angle, $α_{gg}=-3θ_C/4$. The resulting ansatz, $\UPMNS=\VCKM^\dagger\UTBM R_{n_{gg}}(-3θ_C/4)$, contains no new continuous parameter in the Dirac lepton-mixing sector once the structural choice is fixed. With the 2025 Particle Data Group CKM fit it predicts $θ_{12}=33.29^\circ$, $θ_{13}=8.46^\circ$, $θ_{23}=49.19^\circ$, and $\dcp=180.79^\circ$, with CKM-induced uncertainties much smaller than present oscillation errors. We derive leading Wolfenstein sum rules; in particular, the real deformation preserves the CKM-induced suppression $\Jcp=-Aηλ^3/6+\mathcal O(λ^4)$ and hence a near-CP-conserving phase. A retrospective simplicity scan shows that the pair $(2,1,2),3/4$ ranks first among 5510 oriented primitive-integer/rational candidates when tested on epoch-matched 2016 and 2018 oscillation data. In an enlarged 49,622-candidate 2018 scan it is second in raw score but remains first among candidates no more complex than itself under several independent simplicity measures; profiling the rotation strength for the fixed $(2,1,2)$ axis gives $r_{\rm BF}=0.74941$. We formulate the deformation by a convention-covariant flavor-space generator and give an exact effective eigenframe realization $M_ν=A I+B\Sgg+C\Sgg^2$. The construction is presently allowed in normal ordering, with the atmospheric sector providing its strongest pressure; its upper-octant atmospheric angle and near-$π$ Dirac phase provide sharp falsifiability targets.

The mixing of heavy neutral leptons (HNLs) with tau neutrinos remains largely unconstrained compared to their mixing with electron and muon neutrinos. In this work, we investigate the potential of solar neutrinos to improve constraints on HNL-$ν_τ$ mixing in the MeV mass range. Due to neutrino oscillations, the Sun is a copious source of neutrinos of all flavors, and the partial conversion of electron neutrinos into muon and tau neutrinos occurs already during their propagation through the solar interior. Tau neutrinos can produce HNLs through scattering with protons in the Sun, provided nonzero HNL-$ν_τ$ mixing is present. The HNLs escape the Sun and subsequently decay through the same interaction. For $\mathcal{O}(10)$ MeV HNL masses, the dominant visible decay yields electrons and positrons that can be detected by space-based solar observatories. Using data from the Solar and Heliospheric Observatory (SOHO), we search for such signals and derive constraints on the squared HNL-$ν_τ$ mixing matrix element, $|U_{τN}|^2$, reaching below the $10^{-2}$ level for HNL masses of $\sim 5$ MeV. These constraints improve upon existing terrestrial limits in this mass range by more than an order of magnitude.

We classify maximally enhanced, rank-preserving non-supersymmetric heterotic strings in eight dimensions by studying orbifolds of supersymmetric heterotic strings on $T^2$. We first review the construction in nine dimensions, where it reproduces the $95$ maximally semisimple enhancement points obtained from previous extended-Dynkin analyses. We then start from the maximally enhanced supersymmetric Narain points in eight dimensions and use Kac's theorem to enumerate candidate order-two inner actions, retaining only those that lift to consistent Narain-lattice shifts. This gives $1210$ maximal enhancement points, of which $71$ are tachyon-free, and $25$ have neither tachyons nor shifted-sector massless scalars. For each entry we determine the gauge algebra and the low-lying scalar and fermion spectra, and for the tachyon-free cases we evaluate the one-loop cosmological constant. For the 25 subcases without shifted-sector massless scalars, we further compute the Hessian of the one-loop potential and test the refined de Sitter swampland conjecture.