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Search: authors:"Rijun Huang"

10 papers found.
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Expansion of Einstein-Yang-Mills amplitude

In this paper, we study from various perspectives the expansion of tree level single trace Einstein-Yang-Mills amplitudes into linear combination of color-ordered Yang-Mills amplitudes. By applying the gauge invariance principle, a programable recursive construction is devised to expand EYM amplitude with arbitrary number of gravitons into EYM amplitudes with fewer gravitons. Based ...

Understanding the cancelation of double poles in the Pfaffian of CHY-formulism

For a physical field theory, the tree-level amplitudes should possess only single poles. However, when computing amplitudes with Cachazo-He-Yuan (CHY) formulation, individual terms in the intermediate steps will contribute higher-order poles. In this paper, we investigate the cancelation of higher-order poles in CHY formula with Pfaffian as the building block. We develop a ...

Note on recursion relations for the \( \mathcal{Q} \) -cut representation

In this note, we study the \( \mathcal{Q} \)-cut representation by combining it with BCFW deformation. As a consequence, the one-loop integrand is expressed in terms of a recursion relation, i.e., n-point one-loop integrand is constructed using tree-level amplitudes and m-point one-loop integrands with m ≤ n − 1. By giving explicit examples, we show that the integrand from the ...

Form factor and boundary contribution of amplitude

The boundary contribution of an amplitude in the BCFW recursion relation can be considered as a form factor involving boundary operator and unshifted particles. At the tree-level, we show that by suitable construction of Lagrangian, one can relate the leading order term of boundary operators to some composite operators of \( \mathcal{N} \) = 4 superYang-Mills theory, then the ...

Cross-ratio identities and higher-order poles of CHY-integrand

The evaluation of generic Cachazo-He-Yuan(CHY)-integrands is a big challenge and efficient computational methods are in demand for practical evaluation. In this paper, we propose a systematic decomposition algorithm by using cross-ratio identities, which provides an analytic and easy to implement method for the evaluation of any CHY-integrand. This algorithm aims to decompose a ...

Feynman rules of higher-order poles in CHY construction

In this paper, we generalize the integration rules for scattering equations to situations where higher-order poles are present. We describe the strategy to deduce the Feynman rules of higher-order poles from known analytic results of simple CHY-integrands, and propose the Feynman rules for single double pole and triple pole as well as duplex-double pole and triplex-double pole ...

The \( \mathcal{Q} \) -cut representation of one-loop integrands and unitarity cut method

Recently, a new construction for complete loop integrands of massless field theories has been proposed, with on-shell tree-level amplitudes delicately incorporated into its algorithm. This new approach reinterprets integrands in a novel form, namely the \( \mathcal{Q} \)-cut representation. In this paper, by deriving one-loop integrands as examples, we elaborate in details the ...

An algebraic approach to the scattering equations

We employ the so-called companion matrix method from computational algebraic geometry, tailored for zero-dimensional ideals, to study the scattering equations. The method renders the CHY-integrand of scattering amplitudes computable using simple linear algebra and is amenable to an algorithmic approach. Certain identities in the amplitudes as well as rationality of the final ...

Global structure of curves from generalized unitarity cut of three-loop diagrams

This paper studies the global structure of algebraic curves defined by generalized unitarity cut of four-dimensional three-loop diagrams with eleven propagators. The global structure is a topological invariant that is characterized by the geometric genus of the algebraic curve. We use the Riemann-Hurwitz formula to compute the geometric genus of algebraic curves with the help of ...

Integral reduction by unitarity method for two-loop amplitudes: a case study

In this paper, we generalize the unitarity method to two-loop diagrams and use it to discuss the master integrals of reduction. To test out method, we focus on the four-point double-box diagram as well as its related daughter diagrams, i.e., the doubletriangle diagram and the triangle-box diagram. For later two kinds of diagrams, we have given complete analytical results in general ...