scholarly journals The EFT-hedron

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Nima Arkani-Hamed ◽  
Tzu-Chen Huang ◽  
Yu-tin Huang
Keyword(s):  
Scattering Amplitudes ◽  
Effective Field Theory ◽  
Systematic Investigation ◽  
Effective Field ◽  
Low Energy ◽  
Boundary Structure ◽  
Higher Dimension ◽  
Particle Scattering ◽  
Totally Positive ◽  
Positive Structure

Abstract We re-examine the constraints imposed by causality and unitarity on the low-energy effective field theory expansion of four-particle scattering amplitudes, exposing a hidden “totally positive” structure strikingly similar to the positive geometries associated with grassmannians and amplituhedra. This forces the infinite tower of higher-dimension operators to lie inside a new geometry we call the “EFT-hedron”. We initiate a systematic investigation of the boundary structure of the EFT-hedron, giving infinitely many linear and non-linear inequalities that must be satisfied by the EFT expansion in any theory. We illustrate the EFT-hedron geometry and constraints in a wide variety of examples, including new consistency conditions on the scattering amplitudes of photons and gravitons in the real world.

scholarly journals Leading nonlinear tidal effects and scattering amplitudes

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Zvi Bern ◽  
Julio Parra-Martinez ◽  
Radu Roiban ◽  
Eric Sawyer ◽  
Chia-Hsien Shen
Keyword(s):  
Scattering Amplitudes ◽  
Effective Field Theory ◽  
Effective Field ◽  
Higher Dimension ◽  
Tidal Effects ◽  
Position Space ◽  
Spinning Particle ◽  
Tidal Deformations ◽  
Higher Order Corrections ◽  
Double Copy

Abstract We present the two-body Hamiltonian and associated eikonal phase, to leading post-Minkowskian order, for infinitely many tidal deformations described by operators with arbitrary powers of the curvature tensor. Scattering amplitudes in momentum and position space provide systematic complementary approaches. For the tidal operators quadratic in curvature, which describe the linear response to an external gravitational field, we work out the leading post-Minkowskian contributions using a basis of operators with arbitrary numbers of derivatives which are in one-to-one correspondence with the worldline multipole operators. Explicit examples are used to show that the same techniques apply to both bodies interacting tidally with a spinning particle, for which we find the leading contributions from quadratic in curvature tidal operators with an arbitrary number of derivatives, and to effective field theory extensions of general relativity. We also note that the leading post-Minkowskian order contributions from higher-dimension operators manifest double-copy relations. Finally, we comment on the structure of higher-order corrections.

scholarly journals Studies of Deuteron–Proton Collisions at 100 MeV

2021 ◽  
Vol 62 (4) ◽  
Author(s):  
I. Skwira-Chalot ◽  
N. Kalantar-Nayestanaki ◽  
St. Kistryn ◽  
A. Kozela ◽  
E. Stephan
Keyword(s):  
Cross Section ◽  
Effective Field Theory ◽  
Beam Energy ◽  
Effective Field ◽  
Breakup Reaction ◽  
Low Energy ◽  
Chiral Effective Field Theory ◽  
Proton Collisions ◽  
Realistic Potentials ◽  
Good Agreement

AbstractDifferential cross section for the $$^1H(d,pp)n$$ 1 H ( d , p p ) n reaction is sensitive to various dynamical ingredients and allows for thorough tests of theoretical potentials describing the interaction in the three nucleon systems. The analysis of the experimental data collected for the breakup reaction at the beam energy of 100 MeV has been performed and the first cross section results for selected configurations are presented in this paper. They are in good agreement with calculations based on the realistic potentials. Studies at this relatively low energy will also be important for examining awaited calculations within the Chiral Effective Field Theory.

scholarly journals Constraints on the charged currents in general neutrino interactions with sterile neutrinos

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Tong Li ◽  
Xiao-Dong Ma ◽  
Michael A. Schmidt
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Neutral Current ◽  
New Physics ◽  
Effective Field ◽  
Lepton Number ◽  
Low Energy ◽  
Electroweak Scale ◽  
Sterile Neutrinos ◽  
Neutrino Interactions

Abstract In this work we investigate the implication of low-energy precision measurements on the quark-lepton charged currents in general neutrino interactions with sterile neutrinos in effective field theories. The physics in low-energy measurements is described by the low-energy effective field theory extended with sterile neutrinos (LNEFT) defined below the electroweak scale. We also take into account renormalization group running and match the LNEFT onto the Standard Model (SM) effective field theory with sterile neutrinos (SMNEFT) to constrain new physics (NP) above the electroweak scale. The most sensitive low-energy probes are from leptonic decays of pseudoscalar mesons and hadronic tau lepton decays in terms of precise decay branching fractions, the lepton flavor universality and the Cabibbo-Kobayashi-Maskawa (CKM) unitarity. We also consider other constraints including nuclear beta decay. The constraints on charged current operators are generally stronger than the ones for quark-neutrino neutral current operators. We find that the most stringent bounds on the NP scale of lepton-number-conserving and lepton- number-violating operators in SMNEFT are 74 (110) TeV and 9.8 (13) TeV, respectively, for the operators with down (strange) quark.

Effective field theory for low-energy QCD

2014 ◽  
pp. 200-236
Author(s):  
John F. Donoghue ◽  
Eugene Golowich ◽  
Barry R. Holstein
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Effective Field ◽  
Low Energy

scholarly journals Higgs compositeness in Sp(2N) gauge theories – Determining the low-energy constants with lattice calculations

2018 ◽  
Vol 175 ◽  
pp. 08011 ◽  
Author(s):  
Ed Bennett ◽  
Deog Ki Hong ◽  
Jong-Wan Lee ◽  
C.-J. David Lin ◽  
Biagio Lucini ◽  
...  
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Effective Field ◽  
Higgs Model ◽  
Low Energy ◽  
Dirac Fermion ◽  
Global Symmetry ◽  
Composite Higgs ◽  
Lattice Calculations ◽  
Energy Constants

As a first step towards a quantitative understanding of the SU(4)/Sp(4) composite Higgs model through lattice calculations, we discuss the low energy effective field theory resulting from the SU(4) → Sp(4) global symmetry breaking pattern. We then consider an Sp(4) gauge theory with two Dirac fermion flavours in the fundamental representation on a lattice, which provides a concrete example of the microscopic realisation of the SU(4)/Sp(4) composite Higgs model. For this system, we outline a programme of numerical simulations aiming at the determination of the low-energy constants of the effective field theory and we test the method on the quenched theory. We also report early results from dynamical simulations, focussing on the phase structure of the lattice theory and a calculation of the lowest-lying meson spectrum at coarse lattice spacing.

scholarly journals EFT anomalous dimensions from the S-matrix

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Joan Elias Miró ◽  
James Ingoldby ◽  
Marc Riembau
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Form Factors ◽  
Effective Field ◽  
Higher Dimension ◽  
Powerful Method ◽  
Loop Contribution ◽  
Anomalous Dimensions ◽  
S Matrix ◽  
The Standard Model

Abstract We use the on-shell S-matrix and form factors to compute anomalous dimensions of higher dimension operators in the Standard Model Effective Field Theory. We find that in many instances, these computations are made simple by using the on-shell method. We first compute contributions to anomalous dimensions of operators at dimension-six that arise at one-loop. Then we calculate two-loop anomalous dimensions for which the corresponding one-loop contribution is absent, using this powerful method.

scholarly journals Power counting and Wilsonian renormalization in nuclear effective field theory

2016 ◽  
Vol 25 (05) ◽  
pp. 1641007 ◽  
Author(s):  
Manuel Pavón Valderrama
Keyword(s):  
Field Theory ◽  
Effective Field Theories ◽  
Effective Field Theory ◽  
Nuclear Physics ◽  
High Energy ◽  
Effective Field ◽  
Power Counting ◽  
Low Energy ◽  
Field Theories ◽  
Nuclear Forces

Effective field theories are the most general tool for the description of low energy phenomena. They are universal and systematic: they can be formulated for any low energy systems we can think of and offer a clear guide on how to calculate predictions with reliable error estimates, a feature that is called power counting. These properties can be easily understood in Wilsonian renormalization, in which effective field theories are the low energy renormalization group evolution of a more fundamental — perhaps unknown or unsolvable — high energy theory. In nuclear physics they provide the possibility of a theoretically sound derivation of nuclear forces without having to solve quantum chromodynamics explicitly. However there is the problem of how to organize calculations within nuclear effective field theory: the traditional knowledge about power counting is perturbative but nuclear physics is not. Yet power counting can be derived in Wilsonian renormalization and there is already a fairly good understanding of how to apply these ideas to non-perturbative phenomena and in particular to nuclear physics. Here we review a few of these ideas, explain power counting in two-nucleon scattering and reactions with external probes and hint at how to extend the present analysis beyond the two-body problem.

scholarly journals Two-hole bound states from a systematic low-energy effective field theory for magnons and holes in an antiferromagnet

2006 ◽  
Vol 74 (22) ◽  
Author(s):  
C. Brügger ◽  
F. Kämpfer ◽  
M. Moser ◽  
M. Pepe ◽  
U.-J. Wiese
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Bound States ◽  
Effective Field ◽  
Low Energy
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