Field Theory Research Articles

Exploring optimal sensitivity of lepton flavor violating effective couplings at the e+e− colliders

We analyze lepton flavor violation (LFV) using the Standard Model effective field theory (SMEFT) framework at the future lepton colliders. Our focus is on the associated production of tau lepton with electron/muon at the electron-positron (e+e−) colliders, related to four-Fermi SMEFT effective operators. In accordance with the upper limits on effective couplings from lepton flavor violating tau decays, we conduct a cut-based analysis to achieve sufficient signal significance. We utilize the optimal observable technique (OOT) to estimate the optimal sensitivity of the effective couplings. The impact of electron beam polarization and the interplay of signal and background in enhancing the optimal sensitivity of the effective couplings are discussed in detail. We find that the sensitivity of flavor-violating effective couplings is enhanced by order of one for 3 TeV center-of-mass (CM) energy and 1000 fb−1 integrated luminosity at the e+e− colliders. Published by the American Physical Society 2024

Radiative Corrections to Superallowed β Decays in Effective Field Theory

The accuracy of Vud determinations from superallowed β decays critically hinges on control over radiative corrections. Recently, substantial progress has been made on the single-nucleon, universal corrections, while nucleus-dependent effects, typically parametrized by a quantity δNS, are much less well constrained. Here, we lay out a program to evaluate this correction from effective field theory (EFT), highlighting the dominant terms as predicted by the EFT power counting. Moreover, we compare the results to a dispersive representation of δNS and show that the expected momentum scaling applies even in the case of low-lying intermediate states. Our EFT framework paves the way toward calculations of δNS and thereby addresses the dominant uncertainty in Vud. Published by the American Physical Society 2024

Approximate Quantum Error Correcting Codes from Conformal Field Theory

Approximate Quantum Error Correcting Codes from Conformal Field Theory

Bosonic multi-Higgs correlations beyond leading order

The production of multiple Higgs bosons at the LHC and beyond is a strong test of the mechanism of electroweak symmetry breaking. Taking inspiration from recent experimental efforts to move toward limits on triple-Higgs production at the Large Hadron Collider, we consider generic bosonic deviations of HH and HHH production from the Standard Model in the guise of Higgs effective field theory (HEFT). Including one-loop radiative corrections within the HEFT and going up to O(p4) in the momentum expansion, we provide a detailed motivation of the parameter range that the LHC (and future hadron colliders) can explore, through accessing nonstandard coupling modifications and momentum dependencies that probe Higgs boson nonlinearities. In particular, we find that radiative corrections can enhance the sensitivity to Higgs self-coupling modifiers and HEFT-specific momentum dependencies can vastly increase triple-Higgs production, thus providing further motivation to consider these processes during the LHC’s high-luminosity phase. Published by the American Physical Society 2024

Picturing Peace Journalists: An Examination of Social Profiles and Professional Model Diffusion

Changes in global journalism are reflected in myriad cross-national professionalization efforts, including the development and exportation of models for journalism practice. Literature on peace journalism, for instance, suggests that its adaptation across contexts is shaped by forces on several levels, including the influence of individual media practitioners. However, little research examines those likely to practice peace journalism nor the implications of these social profiles on the diffusion of the model more broadly. Drawing on field theory and 20 in-depth interviews with East African journalists conducted between 2020 and 2021, this study explores such questions by identifying shared dimensions of position and habitus across those who attend peace journalism trainings. Findings suggest that these individuals tend to be well educated, share common experiences with conflict, and hold similar interventionist role conceptions. Such findings illuminate the types of social transformations peace journalism may undergo as it is adapted across contexts, with implications for journalism theory and practice.

Regularized-renormalized-resummed loop corrected power spectrum of non-singular bounce with Primordial Black Hole formation

AbstractWe present a complete and consistent exposition of the regularization, renormalization, and resummation procedures in the setup of having a contraction and then non-singular bounce followed by inflation with a sharp transition from slow-roll (SR) to ultra-slow roll (USR) phase for generating primordial black holes (PBHs). We consider following an effective field theory (EFT) approach and study the quantum loop corrections to the power spectrum from each phase. We demonstrate the complete removal of quadratic UV divergences after renormalization and softened logarithmic IR divergences after resummation and illustrate the scheme-independent nature of our renormalization approach. We further show that the addition of a contracting and bouncing phase allows us to successfully generate PBHs of solar-mass order, $$M_\textrm{PBH}\sim \mathcal{O}(M_{\odot })$$ M PBH ∼ O ( M ⊙ ) , by achieving the minimum e-folds during inflation to be $$\Delta N_{\textrm{Total}}\sim \mathcal{O}(60)$$ Δ N Total ∼ O ( 60 ) and in this process successfully evading the strict no-go theorem. We notice that varying the effective sound speed between $$0.88\leqslant c_{s}\leqslant 1$$ 0.88 ⩽ c s ⩽ 1 , allows the peak spectrum amplitude to lie within $$10^{-3}\leqslant A \leqslant 10^{-2}$$ 10 - 3 ⩽ A ⩽ 10 - 2 , indicating that causality and unitarity remain protected in the theory. We analyse PBHs in the extremely small, $$M_{\textrm{PBH}}\sim \mathcal{O}(10^{-33}-10^{-27})M_{\odot }$$ M PBH ∼ O ( 10 - 33 - 10 - 27 ) M ⊙ , and the large, $$M_{\textrm{PBH}}\sim \mathcal{O}(10^{-6}-10^{-1})M_{\odot }$$ M PBH ∼ O ( 10 - 6 - 10 - 1 ) M ⊙ , mass limits and confront the PBH abundance results with the latest microlensing constraints. We also study the cosmological beta functions across all phases and find their interpretation consistent in the context of bouncing and inflationary scenarios while satisfying the pivot scale normalization requirement. Further, we estimate the spectral distortion effects and shed light on controlling PBH overproduction.

A Pure Geometric Field Theory with Parameterized Canonical W-tensor

A Pure Geometric Field Theory with Parameterized Canonical W-tensor

Probing effective operators in single top quark production in association with a lepton-neutrino pair

We study single top quark production in association with a lepton-neutrino pair at the LHC within the framework of the Standard Model effective field theory (SMEFT). We focus on relevant two-quark-two-lepton operators (Olq3, Olequ1, and Olequ3). It is known that these operators have tiny effects on the inclusive cross section of standard model tW production and are thus typically ignored in the SMEFT searches. However, we show that by employing smart observables, such as mT2, the pp→tℓν process is significantly sensitive to these operators. We set the most stringent limit on the coupling strength of the Olq3 operator by reinterpreting the results of a search for new phenomena with two opposite-charge leptons, jets and missing transverse momentum at s=13 TeV performed by the ATLAS collaboration. The limits derived on the Olequ1 and Olequ3 operators are comparable to those obtained from probing EFT effects in pp→tt¯ℓν and pp→tt¯ℓℓ processes at the LHC. Consequently, we propose to include the effects of these three operators on the pp→tℓν process in future global SMEFT analyses to increase the sensitivity and to reduce possible degeneracies. Published by the American Physical Society 2024

Soft-photon theorem for pion-proton elastic scattering revisited

We discuss the reactions πp→πp and πp→πpγ from a general quantum field theory (QFT) point of view, describing these reactions in QCD and lowest relevant order of electromagnetism. We consider the pion-proton elastic scattering both off shell and on shell. The on-shell amplitudes for π±p→π±p scattering are described by two invariant amplitudes, while the off-shell amplitudes contain eight invariant amplitudes. We study the photon emission amplitudes in the soft-photon limit where the center-of-mass photon energy ω→0. The Laurent expansion in ω of the π±p→π±pγ amplitudes is considered and the terms of the orders ω−1 and ω0 are derived. These terms can be expressed by the on-shell invariant amplitudes and their partial derivatives with respect to s and t. The pole term ∝ω−1 in the amplitudes corresponds to Weinberg’s soft-photon theorem and is well known from the literature. We derive the next-to-leading term ∝ω0 using only rigorous methods of QFT. We give the relation of the Laurent series for π0p→π0pγ and Low’s soft-photon theorem. Our formulas for the amplitudes in the limit ω→0 are valid for photon momentum k satisfying k2≥0, k0=ω≥0, that is, for both real and virtual photons. Here we consider a limit where with ω→0 we have also k2→0. We discuss the behavior of the corresponding cross sections for π−p→π−pγ with respect to ω for ω→0. We consider cross sections for unpolarized as well as polarized protons in the initial and final states. Published by the American Physical Society 2024

Field-theory action for the constructive standard model

We introduce a field-theory framework in which fields transform under the little group, rather than the Lorentz group, specific to each particle type. By utilizing these fields, along with spinor products and the x factor, we construct a field-theory action that naturally reproduces the vertices of the constructive standard model (CSM). This approach eliminates unphysical components, significantly reduces the degrees of freedom compared to traditional field theory, and offers deeper insights into the power of constructive amplitudes. Our action is momentum-conserving, Lorentz-invariant, Hermitian, and nonlocal. We also discuss this as a framework for developing new constructive field theories, discussing their essential properties and potential applicability in renormalization theory and nonperturbative calculations. Published by the American Physical Society 2024

Predicting the 21-cm field with a hybrid effective field theory approach

Predicting the 21-cm field with a hybrid effective field theory approach

Axion species scale and axion weak gravity conjecture-like bound

Abstract As a cutoff scale of quantum gravity, the species scale can be defined by the scale at which the perturbativity of the non-renormalizable gravitational interaction begins to break down. Since it is determined by the number of species in the effective field theory, we can find the close connection to the distance conjecture, which predicts the lowering of the cutoff at the asymptotic limit of the moduli space caused by the descent of a tower of states from UV. Meanwhile, the same kind of the cutoff scale can be obtained from any non-renormalizable interaction, in particular the interaction between the axion and the gauge field through the θF ∧ F term. Demanding this ‘axion species scale’ not to exceed the gravitational species scale, we obtain the bound (8π 2/g 2)f ≲ M Pl. This is quite similar to the axion weak gravity conjecture bound, but can be applied to any gauge as well as the string interactions which are relevant to towers of states. We also investigate the implications of the (axion) species scale and the axion weak gravity conjecture-like bound by considering the Peccei-Quinn charge reduction of black hole through the interaction between black hole and the string or wormhole.

Quantum wires with local particle loss: Transport manifestations of fluctuation-induced effects

We investigate the transport properties of a quantum wire of weakly interacting fermions in the presence of local particle loss. We calculate current and conductance in this system due to applied external chemical potential bias that can be measured in experimental realizations of ultracold fermions in quasi one-dimensional traps. Using a Keldysh field theory approach based on the Lindblad equation, we establish a perturbative scheme to study the effect of imbalanced reservoirs. Logarithmically divergent terms are resummed using a renormalization group method, and a novel powerlaw behavior for the conductance as a function of the potential bias across the wire is found. In contrast to the equilibrium case of a potential barrier in a Luttinger liquid, the conductance exhibits a scaling behavior, which depends on the interaction strength and on the loss probability. Repulsive interactions reduce the conductance of the wire while attractive interactions enhance it. However, perfect reflectivity and transparency are only reached in the absence of particle loss. Published by the American Physical Society 2024

From Tradition to Innovation: The Role of Culture Tourism in Transforming Chinese Agriculture

After the merger of China’s Ministry of Culture and the National Tourism Administration into the Ministry of Culture and Tourism in 2018, there was a strong push to advance the strategy of culture–tourism integration, which has shown significant effects on the economy and society. Building on this success, the Chinese government proposed the strategy of agriculture–culture–tourism integration in 2023. However, its impact on the agricultural sector remains unclear. This study employs field theory to explain the impact of culture–tourism integration on the agricultural sector. Drawing from the relevant literature, we construct and statistically analyze the Culture–Tourism Coupling Coordination Degree (CTCCD). Utilizing provincial panel data from China from 2000 to 2022, we employ two-way fixed-effects panel regression to empirically estimate and analyze the effects of the CTCCD on the agricultural GDP, Total Factor Productivity (TFP), and various aspects of crop farming. Our findings reveal several key insights: (i) the CTCCD exhibits a significant negative impact on both agricultural GDP and TFP; (ii) the CTCCD negatively affects the proportion of crop farming within the agricultural sector, suggesting that culture–tourism integration results in weaker development of crop farming compared to forestry, animal husbandry, and fisheries; (iii) the CTCCD demonstrates significant negative effects on the sown area, yield per unit area, and total production of food crops, while positively influencing the per capita income of agricultural workers. These empirical results highlight the complex relationship between culture–tourism integration and agricultural development. Our analysis provides quantitative evidence of the trade-offs involved in pursuing integrated development strategies, adding to the existing research on rural development. The findings indicate that promoting agriculture–culture–tourism integration should be balanced with efforts to accelerate agricultural technological progress.

New purely damped pairs of quasinormal modes in a hot and dense strongly-coupled plasma

Abstract Perturbed black holes exhibit damped oscillations whose eigenfrequencies define their quasinormal modes (QNMs). In the case of asymptotically Anti-de Sitter (AdS) black holes, the spectra of QNMs are related to the near-equilibrium behavior of specific strongly interacting quantum field theories via the holographic gauge-gravity duality. In the present work, we numerically obtain the spectra of homogeneous non-hydrodynamic QNMs of a top-down holographic construction called the 2 R-Charge Black Hole (2RCBH) model, which describes a hot and dense strongly-coupled plasma. The main result is the discovery of a new structure of pairs of purely imaginary QNMs. Those new purely damped QNMs dominate the late time equilibration of the strongly-coupled plasma at large values of the chemical potential, while at lower values the fundamental QNMs are instead ordinary poles with imaginary and real parts describing oscillatory decaying perturbations. We also observe a new phenomenon of asymptotic pole fusion for different pairs of purely imaginary QNMs at asymptotically large values of the chemical potential. This phenomenon corresponds to the asymptotic merging of the two poles within each pair of purely imaginary QNMs, with the different pairs of merged poles being evenly spaced by a constant value of 4π in all the different perturbation channels associated to different irreducible representations of the spatial SO(3) rotation symmetry of the medium. In particular, this indicates that characteristic equilibration times for the plasma develop upper bounds that cannot be surpassed by further doping the medium with increasing values of the chemical potential.

Neutrino oscillation in the presence of background classical sources

Abstract The presence of background classical sources affects a quantum field theory significantly in different ways. Neutrino oscillation is a phenomenon that confirms that neutrinos are massive fermions in nature, a celebrated result in modern physics. Neutrino oscillation plays an important role in many astrophysical observations. However, the interactions between the background classical sources with neutrinos are not often considered. In the present article, we show the effect of some classical sources, namely matter currents, electromagnetic waves, torsion, and gravitational waves on neutrino oscillation. It is shown explicitly that the above sources can change the helicity state of neutrinos during neutrino oscillation.

Inclusion of statistical matter in the nonrelativistic limit of NS-NS supergravity

We combine techniques from kinetic theory and string dualities to couple statistical matter to a nonrelativistic supergravity background, enabling the theory to be formulated in a T-duality invariant form. Similarly to the relativistic case, we explicitly demonstrate that, in the nonrelativistic limit, the many-strings system necessitates a viscous fluid description for describing the statistical matter. This is achieved coupling a generalized energy-momentum tensor in the framework of double field theory, which it is covariant under T-duality transformations. Published by the American Physical Society 2024

On the role of fiducial structures in minisuperspace reduction and quantum fluctuations in LQC

Abstract In spatially non-compact homogeneous minisuperpace models, spatial integrals in the Hamiltonian and symplectic form must be regularised by confining them to a finite volume Vo , known as the fiducial cell. As this restriction is unnecessary in the complete field theory before homogeneous reduction, the physical significance of the fiducial cell has been largely debated, especially in the context of (loop) quantum cosmology. Understanding the role of Vo is in turn essential for assessing the minisuperspace description’s validity and its connection to the full theory. In this work we present a systematic procedure for the field theory reduction to spatially homogeneous and isotropic minisuperspaces within the canonical framework and apply it to both a massive scalar field theory and gravity. Our strategy consists in implementing spatial homogeneity via second-class constraints for the discrete field modes over a partitioning of the spatial slice into countably many disjoint cells. The reduced theory’s canonical structure is then given by the corresponding Dirac bracket. Importantly, the latter can only be defined on a finite number of cells homogeneously patched together. This identifies a finite region, the fiducial cell, whose physical size acquires then a precise meaning already at the classical level as the scale over which homogeneity is imposed. Additionally, the procedure allows us to track the information lost during homogeneous reduction and how the error depends on Vo . We then move to the quantisation of the classically reduced theories, focusing in particular on the relation between the theories for different Vo , and study the implications for statistical moments, quantum fluctuations, and semiclassical states. In the case of a quantum scalar field, a subsector of the full quantum field theory where the results from the ‘first reduced, then quantised’ approach can be reproduced is identified and the conditions for this to be a good approximation are also determined.

Double Copy From Tensor Products of Metric BV■‐Algebras

AbstractField theories with kinematic Lie algebras, such as field theories featuring color–kinematics duality, possess an underlying algebraic structure known as BV■‐algebra. If, additionally, matter fields are present, this structure is supplemented by a module for the BV■‐algebra. The authors explain this perspective, expanding on our previous work and providing many additional mathematical details. The authors also show how the tensor product of two metric BV■‐algebras yields the action of a new syngamy field theory, a construction which comprises the familiar double copy construction. As examples, the authors discuss various scalar field theories, Chern–Simons theory, self‐dual Yang–Mills theory, and the pure spinor formulations of both M2‐brane models and supersymmetric Yang–Mills theory. The latter leads to a new cubic pure spinor action for 10‐dimensional supergravity. A homotopy‐algebraic perspective on colour–flavour‐stripping is also given, obtain a new restricted tensor product over a wide class of bialgebras, and it is also show that any field theory (even one without colour–kinematics duality) comes with a kinematic ‐algebra.

Field theory for superconducting branes and generalized particle-vortex duality

Abstract We propose a field theory of closed p-brane Cp interacting with a (p + 1)-form gauge field Ap+1. This is a generalization of the Ginzburg-Landau theory (Abelian-Higgs model) for superconducting particles to higher-dimensional superconducting branes. A higher-form gauge invariant action is constructed by utilizing the Area derivative, which is a higher-dimensional generalization of the ordinary derivative. We find that the fundamental phenomena of superconductivity, such as the Meisser effect, topological defects, topological order, are naturally extended in the brane-field theory. We explicitly construct a topologically non-trivial static configuration that is characterized by the first homotopy group. Then, we calculate the low-energy effective theory in the presence of the topological defect and find that it is described by a BF-type topological field theory coupled with the world-volume of the topological defect. We also discuss a potential duality between the superconducting brane-field model and a brane-field model with a global U(1) higher-form symmetry as a generalization of the Particle-Vortex duality.