Journal of High Energy Physics最新文献

We employ on-shell methods to construct scattering amplitudes and derive effective theories involving massive spin-3/2 fermions interacting with spin 0, 1 and 2 bosons. The four-point massive amplitudes are constructed using an all-line-transverse momentum shift, assuming that in the massless limit, three-point interactions are smooth and the Ward identity is satisfied. For a Majorana spin-3/2 fermion with mass m_3/2, we show that interactions with only spin 0 and massive spin-1 bosons do not lead to an effective theory valid up to a cutoff Λ ≫ m_3/2 that is independent of particle masses. Instead, adding an interaction with a spin-2 graviton gives rise to four-point amplitudes with a Planck scale unitarity cutoff that reproduces well-known results from N = 1 supergravity, such as F-term breaking with a complex scalar and D-term breaking with an additional massive photon. These bottom-up results are then extended to two Majorana spin-3/2 fermions where an interacting effective theory valid up to Λ ≫ m_3/2 again requires the introduction of the spin-2 graviton. Unitarity up to the Planck scale is then achieved when the two Majorana spin-3/2 fermions have unequal masses, and necessarily couple to two massive spin-1 states corresponding to the spontaneous breaking of N = 2 supergravity to N = 0. Our results, obtained from the bottom-up and without any Lagrangian, imply that broken supergravity is the unique, effective theory involving interactions of massive spin-3/2 fermions valid up to a cutoff Λ ≫ m_3/2 that does not depend on particle masses.

We study three-dimensional gravity with negative cosmological constant under non-standard boundary conditions where chemical potentials are determined dynamically. Using a boundary Hamiltonian inspired by collective field theory (ColFT), the boundary dynamics reduce to those of a one-dimensional fluid on a circle, with configurations corresponding to bulk geometries such as BTZ black holes. Quantizing the system via bosonization of relativistic fermions, we obtain a microscopic description of black hole states in terms of Young diagrams, whose degeneracies match the Bekenstein-Hawking entropy.

We compute the Euclidean canonical partition function and free energy for both the ColFT Hamiltonian and a relativistic free-fermion Hamiltonian. In the ColFT case, the partition function resembles that of chiral U(N) Yang-Mills theory on a torus, with N ~ 1/(βG). This offers a novel way to compute quantum corrections to the partition function. The leading entropy term receives contributions from all genera, while the subleading logarithmic correction is one-loop exact, arising solely from the genus-one sector with coefficient (-frac{1}{2}). This coefficient remains unchanged in the relativistic fermion case, suggesting the universality of the one-loop correction across different boundary Hamiltonians.

We study models that give rise to scalar-tensor effective field theories (EFTs) at low energies. Our framework involves massive particles of spin S = 0, 1/2, 1 coupled to gravity and to a real massless scalar in the UV. Integrating out the massive states leads to a scalar-tensor EFT describing the massless graviton and scalar degrees of freedom. Using the on-shell amplitude methods and the spinor-helicity formalism, we match the two frameworks at one loop, so as to express the EFT Wilson coefficients in terms of the UV masses and coupling. We explore the space of the operators generated in the EFT, including the ones related to the scalar Gauss-Bonnet (SGB) and dynamical Chern-Simons (DCS) gravity theories. We demonstrate that, within our setup, the SGB interactions are always generated with shift-symmetry breaking operators. This is in contrast to the DCS case, where there is a unique choice that preserves the shift symmetry in the IR, corresponding to a theory of spin 1/2 fermions and a complex scalar with a Peccei-Quinn global symmetry.

We discuss the role of heavy scalar fields in mediating neutrinoless double beta decay (0νββ) within the SU(5) Grand Unified Theory framework, extended suitably to include neutrino mass. In such a minimal realistic SU(5) setup for fermion masses, the scalar contributions to 0νββ are extremely suppressed as a consequence of the proton decay bound. We circumvent this problem by imposing a discrete ({mathcal{Z}}_{3}) symmetry. However, the scalar contributions to 0νββ remain suppressed in this (text{SU}(5)times {mathcal{Z}}_{3}) model due to the neutrino mass constraint. We find that the 0νββ contribution can be enhanced by extending the scalar sector with an additional 15-dimensional scalar representation with suitable ({mathcal{Z}}_{3}) charge. Such an extension not only yields realistic fermion mass spectra but also leads to experimentally testable predictions in upcoming ton-scale 0νββ searches, which can be used as a sensitive probe of the new scalars across a broad range, from LHC-accessible scales up to ∼ 10¹⁰ GeV.

First order phase transitions (FOPT) in the early Universe can be powerful emitters of both relativistic and heavy particles, upon the collision of ultra-relativistic bubble shells. If the particles coupling to the bubble wall have CP-violating interactions, the same collision process can also create a local lepton or baryon charge. This CP-violation can originate from different channels, which have only been partially addressed in the literature. We present a systematic analysis of the different channels inducing CP-violation during bubble collisions: 1) the decay of heavy particles 2) the production of heavy particles and 3) the production of light and relativistic Standard Model (SM) particles.

As an illustration of the impact that such mechanisms can have on baryon number and dark matter (DM) abundance, we then introduce a simple model of cogenesis, separating a positive and a negative lepton number in the SM and a dark sector. The lepton number asymmetry in the SM can be used to explain the baryon asymmetry of the Universe (BAU), while the opposite asymmetry in the dark sector is responsible for determining the abundance of DM. Moreover, the masses of light neutrinos can be understood via the inverse seesaw mechanism, with the lepton-violating Majorana mass originating from the FOPT.

A typical signal produced by a FOPT is the irreducible gravitational wave (GW) background. We find that a substantial portion of the parameter space can be probed at future observatories like the Einstein Telescope (ET).

In this study, we examine the domain wall within the framework of a cosmological harmonic oscillator. We investigate the interaction between the domain wall and a periodic background field, which can induce perturbations in the oscillatory behavior of the wall. We propose a novel mechanism for resolving the domain wall problem through the phenomenon of resonant oscillation. Resonant oscillation occurs when the frequency of the external driving force aligns with the intrinsic frequency of the domain wall. This synchrony can significantly amplify the amplitude of the oscillation. If the amplitude of oscillation exceeds a predetermined critical deformation threshold, the domain wall may be deconstructed. Furthermore, we demonstrate that this mechanism remains valid in models that preserve discrete symmetry.

We use methods of arithmetic geometry to find solutions to the abelian local anomaly cancellation equations for a four-dimensional gauge theory whose Lie algebra has a single ({mathfrak{u}}_{1}) summand, assuming that a non-trivial solution exists. The resulting polynomial equations in the integer ({mathfrak{u}}_{1}) charges define a projective cubic hypersurface over the field of rational numbers. Generically, such a hypersurface is (by a theorem of Kollár) unirational, making it possible to find a finitely-many-to-one parameterization of infinitely many solutions using secant and tangent constructions. As an example, for the Standard Model Lie algebra with its three generations of quarks and leptons (or even with just a single generation and two ({mathfrak{s}mathfrak{u}}_{3}oplus {mathfrak{s}mathfrak{u}}_{2}) singlet right-handed neutrinos), it follows that there are infinitely many anomaly-free possibilities for the ({mathfrak{u}}_{1}) hypercharges. We also discuss whether it is possible to find all solutions in this way.

We present a comprehensive study of Kähler moduli stabilisation in Type IIB flux compactifications, combining advanced numerical techniques with analytical methods. Our JAX-based computational framework enables efficient scanning of the UV parameter space, while incorporating α^′ corrections, loop and non-perturbative effects, as well as uplift contributions to the scalar potential. The implementation features rigorous vacuum validation protocols derived from analytic results. We apply our methods to explicit flux compactifications on more than 80,000 Calabi-Yau threefolds with h^1,1 ≤ 6 Kähler moduli. By systematically scanning over a wide range of values of the flux superpotential W₀ and the string coupling g_s, we find explicit realisations of every established Kähler moduli stabilisation scenario: for 10⁻¹⁵ ≤ |W₀| ≤ 10⁻² we obtain both KKLT-like and Kähler uplifted vacua, while for the broader range 10⁻¹ ≤ |W₀| ≤ 10² we recover LVS as well as LVS-like hybrid solutions. Notably, we discover significant parameter regions where multiple vacua coexist within a single flux potential, including novel configurations pairing AdS, Minkowski, and dS minima with different volume hierarchies. These findings enable, for the first time, the analysis of vacuum decay processes within fixed flux configurations, complementing the established theory of transitions between distinct flux vacua and decays towards decompactification.

Rare decays of the kind B → K^∗μ⁺μ⁻ and B_s → ϕμ⁺μ⁻ are key players for testing the Standard Model. The current experimental data for their decay rates and angular observables show tensions with the theoretical predictions that may be indications of New Physics. We present a strategy to extract the relevant short-distance coefficients in the presence of new sources of CP violation from a minimal set of observables, utilizing the synergy between the rare modes with vector meson final states and B → Kμ⁺μ⁻ decays. Using the current data as a guideline, we illustrate the new method to determine the complex coefficients ( {C}_9^{left(prime right)} ) and ( {C}_{10}^{left(prime right)} ) using only four angular observables. Interestingly, the current experimental picture leaves significant room for CP-violating New Physics. We discuss also the link to leptonic ( {B}_s^0to {mu}^{+}{mu}^{-} ) decays. Our strategy complements global fit efforts and could also help to disentangle long-distance QCD dynamics from possible new CP-violating interactions.

We study the impact of the two-loop corrections controlled by the BSM Higgs couplings on the cross section for the production of a pair of SM-like Higgs bosons via gluon fusion in the aligned THDM. To this aim, we reassess the two-loop calculation of λ_hhh, we compute for the first time the two-loop corrections to λ_hhH, and we include the relevant corrections to the Higgs-gluon couplings and to the s-channel propagators entering the gg → hh amplitude. We discuss the numerical impact of the two-loop BSM contributions, first on the individual couplings and then on the prediction for the pair-production cross section, in two benchmark scenarios for the aligned THDM.