Journal of High Energy Physics最新文献

In this paper, we investigate the spectral projection of density matrices in quantum field theory. With appropriate regularization, the spectral projectors of density matrices are expected to be well-defined. These projectors can be obtained using the Riesz projection formula, which allows us to compute both the density of eigenvalues and the expectation values of local operators in the projected states. We find that there are universal divergent terms in the expectation value of the stress energy tensor, where the coefficients depend universally on the density of eigenvalues and a function that describes the dependence of eigenvalues on boundary location. Using projection states, we can construct a series of new states in quantum field theories and discuss their general properties, focusing on the holographic aspects. We observe that quantum fluctuations are suppressed in the semiclassical limit. We also demonstrate that the fixed area state, previously constructed using gravitational path integrals, can be constructed by suitably superposition of appromiate amount of projection states. Additionally, we apply spectral projection to non-Hermitian operators, such as transition matrices, to obtain their eigenvalues and densities. Finally, we highlight potential applications of spectral projections, including the construction of new density and transition matrices and the understanding of superpositions of geometric states.

We incorporate closed string field into Kaku’s open string field theory which is defined using Kaku vertex, and we construct open-closed string field theory. To do this, we define new consistent open-closed vertex and open-open-closed vertex with the Kaku vertex. Because these vertices depend on Chan-Paton parameter such as the Kaku vertex, the open-closed string field theory action that we construct depends on the Chan-Paton parameter such as the Kaku’s theory action. However, we can show that an infinitesimal change in l corresponds to a field redefinition. Furthermore, we compute closed string amplitudes around tachyon vacuum solution in this theory. As a result, we confirm that these amplitudes are conventional pure closed string amplitudes on surfaces without boundaries.

We show how starting with one-string space of states in BRST formalism one can construct a large class of physical quantities containing, in particular, scattering amplitudes for bosonic string and superstring. The same techniques work for heterotic string.

Loop Vertex Expansion (LVE) was developed to construct QFT models with local and non-local interactions. Using LVE, one can prove the analyticity in the finite cardioid-like domain in the complex plain of the coupling constant of the free energies and cumulants of various vector, matrix, or tensor-type models. Here, applying the idea of choosing the initial approximation depending on the coupling constant, we construct the analytic continuation of the free energy of the quartic matrix model beyond the standard LVE cardioid over the branch cut and for arbitrary large couplings.

“Attractor” solutions for the pre-hydrodynamic, far-from-equilibrium, evolution of the matter produced in relativistic heavy ion collisions have emerged as crucial descriptors of the rapid hydrodynamization of quark-gluon plasma (QGP). Adiabatic Hydrodynamization (AH) has been proposed as a framework with which to describe, explain, and predict attractor behavior that draws upon an analogy to the adiabatic approximation in quantum mechanics. In this work, we systematize the description of pre-hydrodynamic attractors in kinetic theory by showing how to use the AH framework to identify these long-lived solutions to which varied initial conditions rapidly evolve, demonstrating the robustness of this framework. In a simplified QCD kinetic theory in the small-angle scattering limit, we use AH to explain both the early- and late-time scaling behavior of a longitudinally expanding gluon gas in a unified framework. In this context, we show that AH provides a unified description of, and intuition for, all the stages of what in QCD would be bottom-up thermalization, starting from a pre-hydrodynamic attractor and ending with hydrodynamization. We additionally discuss the connection between the notions of scaling behavior and adiabaticity and the crucial role of time-dependent coordinate redefinitions in identifying the degrees of freedom of kinetic theories that give rise to attractor solutions. The tools we present open a path to the intuitive explanation of how attractor behavior arises and how the attractor evolves in all stages of the hydrodynamization of QGP in heavy ion collisions.

We investigate the potential of using the signature of mono-Higgs plus large missing energies to constrain on two new ph ysics models, namely the model of an axion-like particle (ALP) and the model of sterile neutrinos. We focus on the Higgs-ALP interactions starting at dimension-six and the Higgs-sterile neutrino interactions starting at dimension-five, via the processes pp → haa for ALP production and pp → hNN for sterile neutrinos at the LHC and High Luminosity LHC (HL-LHC), followed by the Higgs decay ( hto boverline{b} ). We establish bounds on the ALP-Higgs coupling ( frac{C_{aH}}{Lambda^2} ) and sterile neutrino-Higgs coupling ( frac{lambda_3}{M_{ast }} ), respectively, for ALP and sterile-neutrino mass ranging from 1 to 60 GeV, using the recent ATLAS data on mono-Higgs plus missing energies at the LHC (( sqrt{s} ) = 13 TeV and ( mathcal{L} ) = 139 fb⁻¹). The most stringent constraint occurs in the missing transverse energy M_ET range 200 < M_ET ≤ 350 GeV. We also estimate the sensitivities that we can achieve at the HL-LHC (( sqrt{s} ) = 14 TeV and ( mathcal{L} ) = 3000 fb⁻¹). We obtain improved sensitivities across various missing energy regions. The ALP model exhibits better sensitivities, particularly at lower mass range, compared to the sterile neutrino model, which shows weaker sensitivities across similar mass and energy ranges. Our results underscore the potential of the mono-Higgs signature as a robust probe for physics beyond the Standard Model.

In this paper we discuss the geometric integrand expansion of the five-point Wilson loop with one Lagrangian insertion in maximally supersymmetric Yang-Mills theory. We construct the integrand corresponding to an all-loop class of ladder-type geometries. We then investigate the known two-loop observable from this geometric viewpoint. To do so, we evaluate analytically the new two-loop integrals corresponding to the negative geometry contribution, using the canonical differential equations method. Inspecting the analytic result, we present numerical evidence that in this decomposition, each piece has uniform sign properties, when evaluated in the Amplituhedron region. Finally, we present an alternative bootstrap approach for the ladder-type geometries. We find that certain minimal bootstrap assumptions can be satisfied at two loops, but lead to a contradiction at three loops. This suggests to us that novel alphabet letters are required at this loop order. Indeed studying planar three-loop Feynman integrals, we do identify novel pentagon alphabet letters.

The Inverse Seesaw mechanism remains one of the most attractive explanations for the lightness of neutrino masses, allowing for natural low-scale realisations. We consider the prospects of a simple extension via 3 generations of sterile fermions — the so called ISS(3) — in what concerns numerous lepton flavour observables. In order to facilitate a connection between the Lagrangian parameters and low-energy data, we systematically develop new parametrisations of the Yukawa couplings. Relying on these new parametrisations to explore the parameter space, we discuss the complementary role of charged lepton flavour violation searches in dedicated facilities, as well as in lepton colliders (FCC-ee and μTRISTAN). Our results reveal the strong synergy of the different indirect searches in probing the distinct flavour sectors of the model. In particular, we show that in the absence of radiative decays ℓ_α → ℓ_βγ, sizeable rates for Z-penguin dominated observables could hint at a non-trivially mixed and non-degenerate heavy spectrum.

The helicity flux operator is a fascinating quantity that characterizes the angular distribution of the helicity of radiative photons or gravitons and it has many interesting physical consequences. In this paper, we construct the electromagnetic helicity flux operators which form a non-Abelian group in general dimensions, among which the minimal helicity flux operators form the massless representation of the little group, a finite spin unitary irreducible representation of the Poincaré group. As in four dimensions, they generate an extended angle-dependent transformation on the Carrollian manifold. Interestingly, there is no known corresponding bulk duality transformation in general dimensions. However, we can construct a topological Chern-Simons term that evaluates the minimal helicity flux operators at ( {mathcal{I}}^{+} ).

Studying quantum field theories through geometric principles has revealed deep connections between physics and mathematics, including the discovery by Cachazo, Early, Guevara and Mizera (CEGM) of a generalization of biadjoint scalar amplitudes. However, extending this to generalizations of other quantum field theories remains a central challenge. Recently it has been discovered that the nonlinear sigma model (NLSM) emerges after a certain zero-preserving deformation from tr(ϕ³). In this work, we find a much richer story of zero-preserving deformations in the CEGM context, yielding generalized NLSM amplitudes. We prove an explicit formula for the residual embedding of an n-point NLSM amplitude in a mixed n + 2 point generalized NLSM amplitude, which provides a strong consistency check on our generalization. We show that the dimension of the space of pure kinematic deformations is gcd(k, n) − 1, we introduce a deformation-compatible modification of the Global Schwinger Parameterization, and we include a new proof, using methods from matroidal blade arrangements, of the linear independence for the set of planar kinematic invariants for CEGM amplitudes. Our framework is compatible with string theory through recent generalizations of the Koba-Nielsen string integral to any positive configuration space X⁺(k, n), where the usual Koba-Nielsen string integral corresponds to X(2, n) = ( {mathcal{M}}_{0,n} ).