scholarly journals Recursion relations for scattering amplitudes with massive particles

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Sourav Ballav ◽  
Arkajyoti Manna
Keyword(s):  
Gauge Theories ◽  
Tree Level ◽  
Efficient Computation ◽  
Complex Deformation ◽  
Recursion Relations ◽  
Yang Mills ◽  
New Class ◽  
Helicity Formalism ◽  
Vector Bosons ◽  
Massive Spinor

Abstract We use the recently developed massive spinor-helicity formalism [1] of Arkani-Hamed et al. to study a new class of recursion relations for tree-level amplitudes in gauge theories. These relations are based on a combined complex deformation of massless as well as massive external momenta. We use these relations to study tree-level amplitudes in scalar QCD as well as amplitudes involving massive vector bosons in the Higgsed phase of Yang-Mills theory. We prove the validity of our proposal by showing that in the limit of infinite momenta of two of the external particles, the amplitude once again is controlled by an enhanced Spin-Lorentz symmetry paralleling the proof of BCFW shift for massless gauge theories. Simple examples illustrate that the proposed shift may lead to an efficient computation of tree-level amplitudes.

scholarly journals R Symmetry and the Topological Twist of N = 2 Effective Supergravities of Heterotic Strings

1997 ◽  
Vol 12 (02) ◽  
pp. 379-418 ◽  
Author(s):  
Marco Billó ◽  
Pietro Fré ◽  
Riccardo D'auria ◽  
Sergio Ferrara ◽  
Paolo Soriani ◽  
...  
Keyword(s):  
Gauge Theories ◽  
The Other ◽  
Tree Level ◽  
Vector Multiplet ◽  
Continuous Symmetry ◽  
Yang Mills ◽  
Heterotic Strings ◽  
Axion Field ◽  
Effective Theories ◽  
R Symmetry

We discuss R symmetries in locally supersymmetric N = 2 gauge theories coupled to hypermultiplets which can be thought of as effective theories of heterotic superstring models. In this type of supergravities a suitable R symmetry exists and can be used to topologically twist the theory: the vector multiplet containing the dilaton–axion field has different R charge assignments with respect to the other vector multiplets. Correspondingly a system of coupled instanton equations emerges, mixing gravitational and Yang–Mills instantons with triholomorphic hyperinstantons and axion instantons. For the tree level classical special manifolds ST(n) = SU(1,1)/U(1) × SO(2,n)/[SO(2) × SO(n)], R symmetry with the specified properties is a continuous symmetry, but for the quantum-corrected manifolds [Formula: see text] a discrete R group of electric–magnetic duality rotations is sufficient and we argue that it exists.

scholarly journals NON-ABELIAN GAUGE THEORIES AS A CONSEQUENCE OF PERTURBATIVE QUANTUM GAUGE INVARIANCE

1999 ◽  
Vol 14 (21) ◽  
pp. 3421-3432 ◽  
Author(s):  
A. ASTE ◽  
G. SCHARF
Keyword(s):  
Gauge Theory ◽  
Gauge Invariance ◽  
Gauge Theories ◽  
Fundamental Concept ◽  
Abelian Gauge ◽  
Abelian Gauge Theory ◽  
Yang Mills ◽  
Vector Bosons ◽  
Perturbative Quantum

We show for the case of interacting massless vector bosons, how the structure of Yang–Mills theories emerges automatically from a more fundamental concept, namely perturbative quantum gauge invariance. It turns out that the coupling in a non-Abelian gauge theory is necessarily of Yang–Mills type plus divergence- and coboundary-couplings. The extension of the method to massive gauge theories is briefly discussed.

scholarly journals MHV amplitudes and BCFW recursion for Yang-Mills theory in the de Sitter static patch

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Emil Albrychiewicz ◽  
Yasha Neiman ◽  
Mirian Tsulaia
Keyword(s):  
Scattering Problem ◽  
The Other ◽  
Tree Level ◽  
De Sitter ◽  
Recursion Relations ◽  
Yang Mills ◽  
The Past ◽  
Infinite Set ◽  
Mills Field ◽  
Helicity Structure

Abstract We study the scattering problem in the static patch of de Sitter space, i.e. the problem of field evolution between the past and future horizons of a de Sitter observer. We formulate the problem in terms of off-shell fields in Poincare coordinates. This is especially convenient for conformal theories, where the static patch can be viewed as a flat causal diamond, with one tip at the origin and the other at timelike infinity. As an important example, we consider Yang-Mills theory at tree level. We find that static-patch scattering for Yang-Mills is subject to BCFW-like recursion relations. These can reduce any static-patch amplitude to one with N−1MHV helicity structure, dressed by ordinary Minkowski amplitudes. We derive all the N−1MHV static-patch amplitudes from self-dual Yang-Mills field solutions. Using the recursion relations, we then derive from these an infinite set of MHV amplitudes, with arbitrary number of external legs.

scholarly journals Classical and quantum double copy of back-reaction

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Tim Adamo ◽  
Anton Ilderton
Keyword(s):  
Quantum Theory ◽  
Gauge Theory ◽  
Plane Wave ◽  
Tree Level ◽  
Back Reaction ◽  
Quantum Double ◽  
Four Dimensions ◽  
Helicity Formalism ◽  
Massive Spinor ◽  
Double Copy

Abstract We consider radiation emitted by colour-charged and massive particles crossing strong plane wave backgrounds in gauge theory and gravity. These backgrounds are treated exactly and non-perturbatively throughout. We compute the back-reaction on these fields from the radiation emitted by the probe particles: classically through background-coupled worldline theories, and at tree-level in the quantum theory through three-point amplitudes. Consistency of these two methods is established explicitly. We show that the gauge theory and gravity amplitudes are related by the double copy for amplitudes on plane wave backgrounds. Finally, we demonstrate that in four-dimensions these calculations can be carried out with a background-dressed version of the massive spinor-helicity formalism.

scholarly journals PRODUCTION OF NON-ABELIAN TENSOR GAUGE BOSONS TREE AMPLITUDES AND BCFW RECURSION RELATION

2011 ◽  
Vol 26 (15) ◽  
pp. 2537-2555 ◽  
Author(s):  
GEORGE GEORGIOU ◽  
GEORGE SAVVIDY
Keyword(s):  
Scattering Amplitudes ◽  
High Spin ◽  
Recursion Relation ◽  
Coupling Constants ◽  
Tree Level ◽  
Taylor Formula ◽  
Coupling Constant ◽  
Gauge Bosons ◽  
Yang Mills ◽  
Vector Bosons

The BCFW recursion relation is used to calculate tree-level scattering amplitudes in generalized Yang–Mills theory and, in particular, four-particle amplitudes for the production rate of non-Abelian tensor gauge bosons of arbitrary high spin in the fusion of two gluons. The consistency of the calculations in different kinematical channels is fulfilled when all dimensionless cubic coupling constants between vector bosons and high spin non-Abelian tensor gauge bosons are equal to the Yang–Mills coupling constant. We derive a generalization of the Parke–Taylor formula in the case of production of two tensor gauge bosons of spin-s and N gluons (jets). The expression is holomorphic in the spinor variables of the scattered particles, exactly as the MHV gluon amplitude is, and reduces to the gluonic MHV amplitude when s = 1.

scholarly journals One-loop correlators and BCJ numerators from forward limits

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Alex Edison ◽  
Song He ◽  
Oliver Schlotterer ◽  
Fei Teng
Keyword(s):  
Gauge Theories ◽  
Power Counting ◽  
Tree Level ◽  
Loop Momentum ◽  
Gauge Bosons ◽  
Yang Mills ◽  
Spinor Representations

Abstract We present new formulas for one-loop ambitwistor-string correlators for gauge theories in any even dimension with arbitrary combinations of gauge bosons, fermions and scalars running in the loop. Our results are driven by new all-multiplicity expressions for tree-level two-fermion correlators in the RNS formalism that closely resemble the purely bosonic ones. After taking forward limits of tree-level correlators with an additional pair of fermions/bosons, one-loop correlators become combinations of Lorentz traces in vector and spinor representations. Identities between these two types of traces manifest all supersymmetry cancellations and the power counting of loop momentum. We also obtain parity-odd contributions from forward limits with chiral fermions. One-loop numerators satisfying the Bern-Carrasco-Johansson (BCJ) duality for diagrams with linearized propagators can be extracted from such correlators using the well-established tree-level techniques in Yang-Mills theory coupled to biadjoint scalars. Finally, we obtain streamlined expressions for BCJ numerators up to seven points using multiparticle fields.

scholarly journals Celestial operator products of gluons and gravitons

2021 ◽  
pp. 2140003
Author(s):  
Monica Pate ◽  
Ana-Maria Raclariu ◽  
Andrew Strominger ◽  
Ellis Ye Yuan
Keyword(s):  
Operator Product Expansion ◽  
Beta Function ◽  
Tree Level ◽  
Operator Product ◽  
Recursion Relations ◽  
Yang Mills ◽  
Euler Beta Function ◽  
Celestial Sphere ◽  
Asymptotic Symmetries

The operator product expansion (OPE) on the celestial sphere of conformal primary gluons and gravitons is studied. Asymptotic symmetries imply recursion relations between products of operators whose conformal weights differ by half-integers. It is shown, for tree-level Einstein–Yang–Mills theory, that these recursion relations are so constraining that they completely fix the leading celestial OPE coefficients in terms of the Euler beta function. The poles in the beta functions are associated with conformally soft currents.

scholarly journals Charge algebra for non-abelian large gauge symmetries at O(r)

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Miguel Campiglia ◽  
Javier Peraza
Keyword(s):  
Symplectic Structure ◽  
Gauge Theories ◽  
Symmetry Algebra ◽  
Tree Level ◽  
Null Infinity ◽  
Asymptotic Field ◽  
Yang Mills ◽  
Extended Space ◽  
Gauge Symmetries ◽  
Asymptotic Symmetries

Abstract Asymptotic symmetries of gauge theories are known to encode infrared properties of radiative fields. In the context of tree-level Yang-Mills theory, the leading soft behavior of gluons is captured by large gauge symmetries with parameters that are O(1) in the large r expansion towards null infinity. This relation can be extended to subleading order provided one allows for large gauge symmetries with O(r) gauge parameters. The latter, however, violate standard asymptotic field fall-offs and thus their interpretation has remained incomplete. We improve on this situation by presenting a relaxation of the standard asymptotic field behavior that is compatible with O(r) gauge symmetries at linearized level. We show the extended space admits a symplectic structure on which O(1) and O(r) charges are well defined and such that their Poisson brackets reproduce the corresponding symmetry algebra.

scholarly journals Gravity loop integrands from the ultraviolet

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Alex Edison ◽  
Enrico Herrmann ◽  
Julio Parra-Martinez ◽  
Jaroslav Trnka
Keyword(s):  
Scattering Amplitudes ◽  
Momentum Space ◽  
Indirect Evidence ◽  
Tree Level ◽  
Large Momentum ◽  
Recursion Relations ◽  
Yang Mills ◽  
The One ◽  
Geometric Picture ◽  
Super Yang Mills Theory

We demonstrate that loop integrands of (super-)gravity scattering amplitudes possess surprising properties in the ultraviolet (UV) region. In particular, we study the scaling of multi-particle unitarity cuts for asymptotically large momenta and expose an improved UV behavior of four-dimensional cuts through seven loops as compared to standard expectations. For N=8 supergravity, we show that the improved large momentum scaling combined with the behavior of the integrand under BCFW deformations of external kinematics uniquely fixes the loop integrands in a number of non-trivial cases. In the integrand construction, all scaling conditions are homogeneous. Therefore, the only required information about the amplitude is its vanishing at particular points in momentum space. This homogeneous construction gives indirect evidence for a new geometric picture for graviton amplitudes similar to the one found for planar N=4 super Yang-Mills theory. We also show how the behavior at infinity is related to the scaling of tree-level amplitudes under certain multi-line chiral shifts which can be used to construct new recursion relations.

Geometry and Quantum Dynamics

2017 ◽  
Author(s):  
Laurent Baulieu ◽  
John Iliopoulos ◽  
Roland Sénéor
Keyword(s):  
General Relativity ◽  
Quantum Dynamics ◽  
Gauge Theories ◽  
Brst Symmetry ◽  
Abelian Gauge ◽  
Yang Mills ◽  
History Of ◽  
Brst Invariance

A geometrical derivation of Abelian and non- Abelian gauge theories. The Faddeev–Popov quantisation. BRST invariance and ghost fields. General discussion of BRST symmetry. Application to Yang–Mills theories and general relativity. A brief history of gauge theories.

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