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 Generalization of the Yang–Mills theory

2016 ◽  
Vol 31 (01) ◽  
pp. 1630003 ◽  
Author(s):  
G. Savvidy
Keyword(s):  
Beta Function ◽  
Coupling Constants ◽  
Standard Theory ◽  
Large Integer ◽  
Tree Level ◽  
Gauge Fields ◽  
Gauge Bosons ◽  
Yang Mills ◽  
Conformally Invariant ◽  
Vector Gauge

We suggest an extension of the gauge principle which includes tensor gauge fields. In this extension of the Yang–Mills theory the vector gauge boson becomes a member of a bigger family of gauge bosons of arbitrary large integer spins. The proposed extension is essentially based on the extension of the Poincaré algebra and the existence of an appropriate transversal representations. The invariant Lagrangian is expressed in terms of new higher-rank field strength tensors. It does not contain higher derivatives of tensor gauge fields and all interactions take place through three- and four-particle exchanges with a dimensionless coupling constant. We calculated the scattering amplitudes of non-Abelian tensor gauge bosons at tree level, as well as their one-loop contribution into the Callan–Symanzik beta function. This contribution is negative and corresponds to the asymptotically free theory. Considering the contribution of tensorgluons of all spins into the beta function we found that it is leading to the theory which is conformally invariant at very high energies. The proposed extension may lead to a natural inclusion of the standard theory of fundamental forces into a larger theory in which vector gauge bosons, leptons and quarks represent a low-spin subgroup. We consider a possibility that inside the proton and, more generally, inside hadrons there are additional partons — tensorgluons, which can carry a part of the proton momentum. The extension of QCD influences the unification scale at which the coupling constants of the Standard Model merge, shifting its value to lower energies.

scholarly journals The World as Quarks, Leptons and Bosons

1976 ◽  
Vol 29 (6) ◽  
pp. 347 ◽  
Author(s):  
M Gell-Mann
Keyword(s):  
Gauge Theory ◽  
Gauge Theories ◽  
Strong Interactions ◽  
Gauge Bosons ◽  
Yang Mills ◽  
Electromagnetic Interactions ◽  
The World

A descriptive review is given of gauge theories of weak, electromagnetic and strong interactions. The strong interactions are interpreted in terms of an unbroken Yang-Mills gauge theory based on SU(3) colour symmetry of quarks and gluons. The confinement mechanism of quarks, gluons and other nonsinglets is discussed. The unification of the weak and electromagnetic interactions through a broken Yang-Mills gauge theory is described. In total the basic constituents are then the quarks, leptons and gauge bosons.

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 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 CONFORMAL INVARIANCE OF TENSOR BOSON TREE AMPLITUDES

2012 ◽  
Vol 27 (18) ◽  
pp. 1250103 ◽  
Author(s):  
IGNATIOS ANTONIADIS ◽  
GEORGE SAVVIDY
Keyword(s):  
Scattering Amplitudes ◽  
Conformal Invariance ◽  
Recursion Relation ◽  
Conformal Group ◽  
Tree Level ◽  
Unexpected Result ◽  
Gauge Bosons ◽  
Yang Mills ◽  
Higher Spin

The BCFW recursion relation allows to find out the tree-level scattering amplitudes for gluons and tensor gauge bosons in generalized Yang–Mills theory. We demonstrate that the corresponding MHV amplitudes for the tensor gauge bosons of spin-s and n gluons are invariant under conformal group of transformations. This is highly unexpected result for the higher-spin particles, in particular this is not true for the scattering amplitudes of gravitons. We discuss and compare the tree-level scattering amplitudes for the charged tensor bosons with the corresponding scattering amplitudes for gravitons, stressing their differences and similarities.

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 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.

A non-abelian model SU(N) × SU(N)

2015 ◽  
Vol 8 (1) ◽  
pp. 1988-2004
Author(s):  
Renato Doria ◽  
M. J. Neves
Keyword(s):  
Gauge Symmetry ◽  
Momentum Space ◽  
Brst Symmetry ◽  
Power Counting ◽  
Physical Application ◽  
Tree Level ◽  
Color Symmetry ◽  
Yang Mills ◽  
Loop Approximation ◽  
Feynman Rules

A composite non-abelian model SU(N) × SU(N) is proposed as possible extension of the Yang-Mills symmetry. We obtain the corresponding gauge symmetry of the model and the most general lagrangian invariant by SU(N) × SU(N). The corresponding Feynman rules of the model are studied. Propagators and vertices are derived in the momentum space. As physical application, instead of considering the color symmetry SUc(3) for QCD, we substitute it by the combination SUc(3) × SUc(3). It yields a possibility to go beyond QCD symmetry in the sense that quarks are preserved with three colors. This extension provides composite quarks in triplets and sextets multiplets accomplished with the usual massless gluons plus massive gluons. We present a power counting analysis that satisfies the renormalization conditions as well as one studies the structure of radiative corrections to one loop approximation. Unitary condition is verified at tree level. Tachyons are avoided. For end, one extracts a BRST symmetry from lagrangian and Slavnov-Tayloridentities.

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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