Effective Theory Description of Weak Annihilation in Decays

Effective field theory (EFT) is a general method for describing quantum systems with multiple-length scales in a tractable fashion. It allows us to perform precise calculations in established models (such as the standard models of particle physics and cosmology), as well as to concisely parametrize possible effects from physics beyond the standard models. EFTs have become key tools in the theoretical analysis of particle physics experiments and cosmological observations, despite being absent from many textbooks. This volume aims to provide a comprehensive introduction to many of the EFTs in use today, and covers topics that include large-scale structure, WIMPs, dark matter, heavy quark effective theory, flavour physics, soft-collinear effective theory, and more.

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Excited heavy baryons and their symmetries II: Effective theory

Nuclear Physics A ◽

10.1016/s0375-9474(01)00656-x ◽

2001 ◽

Vol 692 (3-4) ◽

pp. 521-545 ◽

Cited By ~ 5

Author(s):

Chi-Keung Chow ◽

Thomas D. Cohen ◽

Boris A. Gelman

Keyword(s):

Effective Theory ◽

Heavy Baryons

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Unitarity in KK-graviton production, a case study in warped extra-dimensions

Journal of High Energy Physics ◽

10.1007/jhep04(2021)143 ◽

2021 ◽

Vol 2021 (4) ◽

Author(s):

A. de Giorgi ◽

S. Vogl

Keyword(s):

Extra Dimensions ◽

Sum Rules ◽

Effective Theory ◽

Higher Dimensional ◽

Massive Spin ◽

The Matrix ◽

Dimensional Gravity ◽

Warped Extra Dimensions ◽

Kaluza Klein

Abstract The Kaluza-Klein (KK) decomposition of higher-dimensional gravity gives rise to a tower of KK-gravitons in the effective four-dimensional (4D) theory. Such massive spin-2 fields are known to be connected with unitarity issues and easily lead to a breakdown of the effective theory well below the naive scale of the interaction. However, the breakdown of the effective 4D theory is expected to be controlled by the parameters of the 5D theory. Working in a simplified Randall-Sundrum model we study the matrix elements for matter annihilations into massive gravitons. We find that truncating the KK-tower leads to an early breakdown of perturbative unitarity. However, by considering the full tower we obtain a set of sum rules for the couplings between the different KK-fields that restore unitarity up to the scale of the 5D theory. We prove analytically that these are fulfilled in the model under consideration and present numerical tests of their convergence. This work complements earlier studies that focused on graviton self-interactions and yields additional sum rules that are required if matter fields are incorporated into warped extra-dimensions.

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A diquark chiral effective theory and exotic baryons

Physics Letters B ◽

10.1016/j.physletb.2004.06.073 ◽

2004 ◽

Vol 596 (3-4) ◽

pp. 191-199 ◽

Cited By ~ 15

Author(s):

Deog Ki Hong ◽

Young Jin Sohn ◽

Ismail Zahed

Keyword(s):

Effective Theory ◽

Exotic Baryons

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An effective theory of type refinements

ACM SIGPLAN Notices ◽

10.1145/944746.944725 ◽

2003 ◽

Vol 38 (9) ◽

pp. 213-225 ◽

Cited By ~ 2

Author(s):

Yitzhak Mandelbaum ◽

David Walker ◽

Robert Harper

Keyword(s):

Effective Theory

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Disentangling QCD and new physics in D → πℓ+ℓ−

Journal of High Energy Physics ◽

10.1007/jhep04(2021)158 ◽

2021 ◽

Vol 2021 (4) ◽

Author(s):

Aoife Bharucha ◽

Diogo Boito ◽

Cédric Méaux

Keyword(s):

Standard Model ◽

Branching Ratio ◽

Branching Ratios ◽

New Physics ◽

Operator Product ◽

Beyond The Standard Model ◽

Spectral Functions ◽

The Standard Model ◽

Model Independent ◽

Weak Annihilation

Abstract In this paper we consider the decay D+ → π+ℓ+ℓ−, addressing in particular the resonance contributions as well as the relatively large contributions from the weak annihilation diagrams. For the weak annihilation diagrams we include known results from QCD factorisation at low q2 and at high q2, adapting the existing calculation for B decays in the Operator Product Expansion. The hadronic resonance contributions are obtained through a dispersion relation, modelling the spectral functions as towers of Regge-like resonances in each channel, as suggested by Shifman, imposing the partonic behaviour in the deep Euclidean. The parameters of the model are extracted using e+e− → (hadrons) and τ → (hadrons) + ντ data as well as the branching ratios for the resonant decays D+ → π+R(R → ℓ+ℓ−), with R = ρ, ω, and ϕ. We perform a thorough error analysis, and present our results for the Standard Model differential branching ratio as a function of q2. Focusing then on the observables FH and AFB, we consider the sensitivity of this channel to effects of physics beyond the Standard Model, both in a model independent way and for the case of leptoquarks.

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Derive Lovelock gravity from string theory in cosmological background

Journal of High Energy Physics ◽

10.1007/jhep05(2021)218 ◽

2021 ◽

Vol 2021 (5) ◽

Author(s):

Peng Wang ◽

Houwen Wu ◽

Haitang Yang ◽

Shuxuan Ying

Keyword(s):

String Theory ◽

Effective Action ◽

Strong Support ◽

Effective Theory ◽

Quadratic Term ◽

Lovelock Gravity ◽

Cosmological Background ◽

Finite Term ◽

Specific Dimension ◽

Bonnet Term

Abstract It was proved more than three decades ago, that the first order α′ correction of string effective theory could be written as the Gauss-Bonnet term, which is the quadratic term of Lovelock gravity. In cosmological background, with an appropriate field redefinition, we reorganize the infinite α′ corrections of string effective action into a finite term expression for any specific dimension. This finite term expression matches Lovelock gravity exactly and thus fix the couplings of Lovelock gravity by the coefficients of string effective action. This result thus provides a strong support to string theory.

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Consistent treatment of rapidity divergence in soft-collinear effective theory

Journal of High Energy Physics ◽

10.1007/jhep03(2021)300 ◽

2021 ◽

Vol 2021 (3) ◽

Author(s):

Junegone Chay ◽

Chul Kim

Keyword(s):

Heavy Quark ◽

Soft Mode ◽

Form Factors ◽

Effective Theory ◽

Large Rapidity ◽

Soft Modes ◽

Heavy Quark Mass ◽

Soft Collinear Effective Theory ◽

Matching Procedure ◽

Consistent Treatment

Abstract In soft-collinear effective theory, we analyze the structure of rapidity divergence due to the collinear and soft modes residing in disparate phase spaces. The idea of an effective theory is applied to a system of collinear modes with large rapidity and soft modes with small rapidity. The large-rapidity (collinear) modes are integrated out to obtain the effective theory for the small-rapidity (soft) modes. The full SCET with the collinear and soft modes should be matched onto the soft theory at the rapidity boundary, and the matching procedure becomes exactly the zero-bin subtraction. The large-rapidity region is out of reach for the soft mode, which results in the rapidity divergence. The rapidity divergence in the collinear sector comes from the zero-bin subtraction, which ensures the cancellation of the rapidity divergences from the soft and collinear sectors. In order to treat the rapidity divergence, we construct the rapidity regulators consistently for all the modes. They are generalized by assigning independent rapidity scales for different collinear directions. The soft regulator incorporates the correct directional dependence when the innate collinear directions are not back-to-back, which is discussed in the N-jet operator. As an application, we consider the Sudakov form factor for the back-to-back collinear current and the soft-collinear current, where the soft rapidity regulator for a soft quark is developed. We extend the analysis to the boosted heavy quark sector and exploit the delicacy with the presence of the heavy quark mass. We present the resummed results of large logarithms in the form factors for various currents with the light and the heavy quarks, employing the renormalization group evolution on the renormalization and the rapidity scales.

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The low-energy effective theory of axions and ALPs

Journal of High Energy Physics ◽

10.1007/jhep04(2021)063 ◽

2021 ◽

Vol 2021 (4) ◽

Author(s):

Martin Bauer ◽

Matthias Neubert ◽

Sophie Renner ◽

Marvin Schnubel ◽

Andrea Thamm

Keyword(s):

High Energy ◽

New Physics ◽

Mass Scale ◽

Low Energy ◽

Effective Theory ◽

Loop Order ◽

Flavor Changing ◽

Effective Lagrangian ◽

Anomalous Dimensions ◽

Pseudoscalar Mesons

Abstract Axions and axion-like particles (ALPs) are well-motivated low-energy relics of high-energy extensions of the Standard Model, which interact with the known particles through higher-dimensional operators suppressed by the mass scale Λ of the new-physics sector. Starting from the most general dimension-5 interactions, we discuss in detail the evolution of the ALP couplings from the new-physics scale to energies at and below the scale of electroweak symmetry breaking. We derive the relevant anomalous dimensions at two-loop order in gauge couplings and one-loop order in Yukawa interactions, carefully considering the treatment of a redundant operator involving an ALP coupling to the Higgs current. We account for one-loop (and partially two-loop) matching contributions at the weak scale, including in particular flavor-changing effects. The relations between different equivalent forms of the effective Lagrangian are discussed in detail. We also construct the effective chiral Lagrangian for an ALP interacting with photons and light pseudoscalar mesons, pointing out important differences with the corresponding Lagrangian for the QCD axion.

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