1.

Symmetries of celestial amplitudes
/ Stieberger, Stephan ; Taylor, Tomasz R.
Celestial amplitudes provide holographic imprints of fourdimensional scattering processes in terms of conformal correlation functions on a twodimensional sphere describing Minkowski space at null infinity. [...]
Published in Physics letters B (2019)
10.1016/j.physletb.2019.03.063
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2.

Strings on celestial sphere
/ Stieberger, Stephan ; Taylor, Tomasz R.
We transform superstring scattering amplitudes into the correlation functions of primary conformal fields on twodimensional celestial sphere. [...]
Published in Nuclear Physics B (2018)
10.1016/j.nuclphysb.2018.08.019
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3.

New relations for Einstein–Yang–Mills amplitudes
/ Stieberger, Stephan ; Taylor, Tomasz R.
We obtain new relations between Einstein–Yang–Mills (EYM) amplitudes involving N gauge bosons plus a single graviton and pure Yang–Mills amplitudes involving N gauge bosons plus one additional vector boson inserted in a way typical for a gauge boson of a “spectator” group commuting with the group associated to original N gauge bosons. [...]
Published in Nuclear Physics B (2016)
10.1016/j.nuclphysb.2016.09.014
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4.

A Feynman integral and its recurrences and associators
/ Puhlfürst, Georg ; Stieberger, Stephan
We determine closed and compact expressions for the ϵ expansion of certain Gaussian hypergeometric functions expanded around halfinteger values by explicitly solving for their recurrence relations. [...]
Published in Nuclear Physics B (2016)
10.1016/j.nuclphysb.2016.03.008
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5.

Disk scattering of open and closed strings (I)
/ Stieberger, Stephan ; Taylor, Tomasz R.
At the tree level, the scattering processes involving open and closed strings are described by a disk worldsheet with vertex operator insertions at the boundary and in the bulk. [...]
Published in Nuclear Physics B (2015)
10.1016/j.nuclphysb.2015.12.002
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6.

Differential equations, associators, and recurrences for amplitudes
/ Puhlfürst, Georg ; Stieberger, Stephan
We provide new methods to straightforwardly obtain compact and analytic expressions for ϵ expansions of functions appearing in both field and string theory amplitudes. [...]
Published in Nuclear Physics B (2015)
10.1016/j.nuclphysb.2015.11.005
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7.

Subleading terms in the collinear limit of Yang–Mills amplitudes
/ Stieberger, Stephan ; Taylor, Tomasz R.
For two massless particles i and j , the collinear limit is a special kinematic configuration in which the particles propagate with parallel fourmomentum vectors, with the total momentum P distributed as pi=xP and pj=(1−x)P , so that sij≡(pi+pj)2=P2=0 . [...]
Published in Physics letters B (2015)
10.1016/j.physletb.2015.09.075
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8.

Graviton amplitudes from collinear limits of gauge amplitudes
/ Stieberger, Stephan ; Taylor, Tomasz R.
We express all treelevel graviton amplitudes in Einstein's gravity as the collinear limits of a linear combination of pure Yang–Mills amplitudes in which each graviton is represented by two gauge bosons, each of them carrying exactly one half of graviton's momentum and helicity..
Published in Physics letters B 744 (2015) 160162
10.1016/j.physletb.2015.03.053
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9.

Graviton as a pair of collinear gauge bosons
/ Stieberger, Stephan ; Taylor, Tomasz R.
We show that the mixed gravitational/gauge superstring amplitudes describing decays of massless closed strings – gravitons or dilatons – into a number of gauge bosons, can be written at the tree (disk) level as linear combinations of pure open string amplitudes in which the graviton (or dilaton) is replaced by a pair of collinear gauge bosons. [...]
Published in Physics letters B 739 (2014) 457461
10.1016/j.physletb.2014.10.057
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10.

Closed string amplitudes as singlevalued open string amplitudes
/ Stieberger, Stephan ; Taylor, Tomasz R.
We show that the single trace heterotic N point treelevel gauge amplitude ${\mathcal{A}}_{N}^{\mathrm{HET}}$ can be obtained from the corresponding type I amplitude ${\mathcal{A}}_{N}^{\mathrm{I}}$ by the singlevalued (sv) projection: ${\mathcal{A}}_{N}^{\mathrm{HET}}=\mathrm{sv}({\mathcal{A}}_{N}^{\mathrm{I}})$ . [...]
Published in Nuclear Physics B 881 (2014) 269287
10.1016/j.nuclphysb.2014.02.005
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