1,029 research outputs found
Note on Identities Inspired by New Soft Theorems
The new soft theorems, for both gravity and gauge amplitudes, have inspired a
number of works, including the discovery of new identities related to
amplitudes. In this note, we present the proof and discussion for two sets of
identities. The first set includes an identity involving the half-soft function
which had been used in the soft theorem for one-loop rational gravity
amplitudes, and another simpler identity as its byproduct. The second set
includes two identities involving the KLT momentum kernel, as the consistency
conditions of the KLT relation plus soft theorems for both gravity and gauge
amplitudes. We use the CHY formulation to prove the first identity, and
transform the second one into a convenient form for future discussion.Comment: 17 page
Derivation of Feynman Rules for Higher Order Poles Using Cross-ratio Identities in CHY Construction
In order to generalize the integration rules to general CHY integrands which
include higher order poles, algorithms are proposed in two directions. One is
to conjecture new rules, and the other is to use the cross-ratio identity
method. In this paper,we use the cross-ratio identity approach to re-derive the
conjectured integration rules involving higher order poles for several special
cases: the single double pole, single triple pole and duplex-double pole. The
equivalence between the present formulas and the previously conjectured ones is
discussed for the first two situations.Comment: 29 pages, 11 figure
On Multi-step BCFW Recursion Relations
In this paper, we extensively investigate the new algorithm known as the
multi-step BCFW recursion relations. Many interesting mathematical properties
are found and understanding these aspects, one can find a systematic way to
complete the calculation of amplitude after finite, definite steps and get the
correct answer, without recourse to any specific knowledge from field theories,
besides mass dimension and helicities. This process consists of the pole
concentration and inconsistency elimination. Terms that survive inconsistency
elimination cannot be determined by the new algorithm. They include polynomials
and their generalizations, which turn out to be useful objects to be explored.
Afterwards, we apply it to the Standard Model plus gravity to illustrate its
power and limitation. Ensuring its workability, we also tentatively discuss how
to improve its efficiency by reducing the steps.Comment: 38 pages, 13 figures, 3 appendice
Explaining the DAMPE data with scalar dark matter and gauged interaction
Inspired by the peak structure observed by recent DAMPE experiment in
cosmic-ray spectrum, we consider a scalar dark matter (DM) model with
gauged symmetry, which is the most economical anomaly-free
theory to potentially explain the peak by DM annihilation in nearby subhalo. We
utilize the process , where , , denote the scalar DM,
the new gauge boson and , respectively, to generate the
spectrum. By fitting the predicted spectrum to the experimental data,
we obtain the favored DM mass range and at
Confidence Level (C.L.). Furthermore, we determine the parameter space
of the model which can explain the peak and meanwhile satisfy the constraints
from DM relic abundance, DM direct detection and the collider bounds. We
conclude that the model we consider can account for the peak, although there
exists a tension with the constraints from the LEP-II bound on
arising from the cross section measurement of .Comment: 15 pages, 4 figure
Determination of Boundary Contributions in Recursion Relation
In this paper, we propose a new algorithm to systematically determine the
missing boundary contributions, when one uses the BCFW on-shell recursion
relation to calculate tree amplitudes for general quantum field theories. After
an instruction of the algorithm, we will use several examples to demonstrate
its application, including amplitudes of color-ordered phi-4 theory, Yang-Mills
theory, Einstein-Maxwell theory and color-ordered Yukawa theory with phi-4
interaction.Comment: 20 pages, 1 appendi
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