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All one-loop NMHV gluon amplitudes
in N = 1 SYM
based on arXiv:1311.1491 [hep-th]
Alexander OchirovIPhT, CEA-Saclay, France
Presented atCERN Theory DivisionNovember 29, 2013
Amplitudes
p1
p2
p3 p4
p5
. . .
pn
Amplitudes
p1
p2
p3 p4
p5
. . .
pn
◮ basic objects in QFT
Amplitudes
p1
p2
p3 p4
p5
. . .
pn
◮ basic objects in QFT
◮ measurable at experiment
Amplitudes
p1
p2
p3 p4
p5
. . .
pn
◮ basic objects in QFT
◮ measurable at experiment
◮ calculable analytically
Known one-loop amplitudes
One-loop gluon amplitudes known analytically:
MHV NMHV
N = 4 SYM n-point byBern,Dixon,Dunbar,Kosower
’94 [1] n-point by Bern,Dixon,Kosower
’04 [2]
N = 1 SYM n-point byBern,Dixon,Dunbar,Kosower
’94 [3] 6-point byBritto,Buchbinder,Cachazo,Feng
’05 [4]
7-point by Bjerrum-Bohr,Dunbar,Perkins
’07 [5]
and Dunbar,Perkins,Warrick
’09 [6],
n-point by AO’13
QCD n-point byBedford,Brandhuber,Spence,Travaglini
’04 [7] 6-point by Britto,Feng,Mastrolia
’06 [8]
andBerger,Bern,Dixon,Forde,Kosower
’06 [9] and Xiao,Yang,Zhu
’06 [10]
Content
1. Setup: NMHV amplitudes in N = 1 SYM at one loop
2. Method: spinor integration
3. Cut construction
4. Results
5. Conclusion and outlook
Yang-Mills theories
Particle content:
helicity 1 1/2 0 −1/2 −1
N = 4 SYM 1 4 6 4 1
N = 1 SYM 1 1 0 1 1
QCD 1 0 0 0 1
Yang-Mills theories at one loop
helicity 1 1/2 0 −1/2 −1
N = 4 SYM 1 4 6 4 1N = 1 SYM 1 1 0 1 1QCD 1 0 0 0 1
Yang-Mills theories at one loop
helicity 1 1/2 0 −1/2 −1
N = 4 SYM 1 4 6 4 1N = 1 SYM 1 1 0 1 1QCD 1 0 0 0 1
A1-loopQCD = A1-loop
N=4 SYM − 4A1-loopN=1 chiral + 2A1-loop
N=0 scalar (1)
Yang-Mills theories at one loop
helicity 1 1/2 0 −1/2 −1
N = 4 SYM 1 4 6 4 1N = 1 SYM 1 1 0 1 1QCD 1 0 0 0 1
A1-loopQCD = A1-loop
N=4 SYM − 4A1-loopN=1 chiral + 2A1-loop
N=0 scalar (1)
A1-loopN=1 SYM = A1-loop
N=4 SYM − 3A1-loopN=1 chiral (2)
Yang-Mills theories at one loop
helicity 1 1/2 0 −1/2 −1
N = 4 SYM 1 4 6 4 1N = 1 SYM 1 1 0 1 1QCD 1 0 0 0 1
A1-loopQCD = A1-loop
N=4 SYM − 4A1-loopN=1 chiral + 2A1-loop
N=0 scalar (1)
A1-loopN=1 SYM = A1-loop
N=4 SYM − 3A1-loopN=1 chiral (2)
N = 1 chiral 0 1 2 1 0N = 0 scalar 0 0 1 0 0
Helicity configurations in SYM
◮ All helicities plus
Helicity configurations in SYM
◮ All helicities plus — zero by SUSY
Helicity configurations in SYM
◮ All helicities plus — zero by SUSY
◮ One minus
Helicity configurations in SYM
◮ All helicities plus — zero by SUSY
◮ One minus — zero by SUSY
Helicity configurations in SYM
◮ All helicities plus — zero by SUSY
◮ One minus — zero by SUSY
◮ Two minuses
Helicity configurations in SYM
◮ All helicities plus — zero by SUSY
◮ One minus — zero by SUSY
◮ Two minuses — MHV (Maximally-Helicity-Violating)
Helicity configurations in SYM
◮ All helicities plus — zero by SUSY
◮ One minus — zero by SUSY
◮ Two minuses — MHV (Maximally-Helicity-Violating)
◮ Three minuses
Helicity configurations in SYM
◮ All helicities plus — zero by SUSY
◮ One minus — zero by SUSY
◮ Two minuses — MHV (Maximally-Helicity-Violating)
◮ Three minuses — NMHV (Next-to-Maximally-Helicity-Violating)
◮ . . . k minuses
Helicity configurations in SYM
◮ All helicities plus — zero by SUSY
◮ One minus — zero by SUSY
◮ Two minuses — MHV (Maximally-Helicity-Violating)
◮ Three minuses — NMHV (Next-to-Maximally-Helicity-Violating)
◮ . . . k minuses — Nk−2MHV
Helicity configurations in SYM
◮ All helicities plus — zero by SUSY
◮ One minus — zero by SUSY
◮ Two minuses — MHV (Maximally-Helicity-Violating)
◮ Three minuses — NMHV (Next-to-Maximally-Helicity-Violating)
◮ . . . k minuses — Nk−2MHV
ANMHV5 =
(
AMHV5
)∗
Helicity configurations in SYM
◮ All helicities plus — zero by SUSY
◮ One minus — zero by SUSY
◮ Two minuses — MHV (Maximally-Helicity-Violating)
◮ Three minuses — NMHV (Next-to-Maximally-Helicity-Violating)
◮ . . . k minuses — Nk−2MHV
ANMHV5 =
(
AMHV5
)∗
NMHV important 6+ ext. particles
N = 1 SYM at one loop
A1-loopN=1 SYM = A1-loop
N=4 SYM − 3A1-loopN=1 chiral (3)
A1-loopN=2 SYM = A1-loop
N=4 SYM − 2A1-loopN=1 chiral (4)
A1-loop = µ2ǫ(
∑
Cbox I4 +∑
Ctri I3 +∑
Cbub I2 +R)
, (5)
from susy power-counting R = 0.
UV and IR behavior
In = (−1)n+1(4π)d2 i
∫
ddl1(2π)d
1
l21(l1 −K1)2 . . . (l1 −Kn−1)2(6)
Britto,Buchbinder,Cachazo,Feng
’05 [4]: two-mass and one-mass triangles O( 1ǫ2)
cancel divergences inside boxes⇒ finite boxes and only three-mass triangles
A1-loopN=1 chiral =
1
ǫ
∑
Cbub +O(1) =1
(4π)d2 ǫ
Atree +O(1) (7)
∑
Cbub =1
(4π)d2
Atree (8)
NMHV three-mass triangles
already known thanks toBjerrum-Bohr,Dunbar,Perkins
’07 [5]
(s3+1)+. . .m−
1
. . .
s+1
(s1+1)+ . . . m−2 . . . s+2
(s2+1)+
. . .
m−3. . .
s+3
Method: spinor integration
Thanks to Britto, Feng et al.
Cut =∑
h1,h2
∫
d4l1 δ(l21)δ(l
22)A(−lh̄1
1 , . . . , lh22 )A(−lh̄2
2 , . . . , lh11 ) (9)
lµ1 =K2
2
〈λ| γµ|λ̃]
〈λ|K|λ̃], lµ2 = −
1
2
〈λ|K|γµ|K|λ̃]
〈λ|K|λ̃]
⇒
∫
d4l1 δ(l21)δ(l
22) = −
K2
4
∫
λ̃=λ̄
〈λdλ〉 [λ̃dλ̃]
〈λ|K|λ̃]2(10)
⇒ Cut =
∫
λ̃=λ̄
〈λdλ〉 [λ̃dλ̃] Ispinor(λ, λ̃) (11)
Spinor integration: complex analysis in disguise
λ = λp + zλq, λ̃ = λ̃p + z̄λ̃q (12)
∫
λ̃=λ̄
〈λdλ〉 [λ̃dλ̃] = −(p+ q)2∫
dz ∧ dz̄ (13)
⇒ Cauchy’s integral theorem (Mastrolia’09 [11]):
∫∫
D
dz ∧ dz̄∂f
∂z̄(z, z̄) = −
∮
∂D
dz f(z, z̄) + 2πi∑
zi∈D
Resz=zi
f(z, z̄)
(14)
Simple pole 〈λ|ζ〉: Resλ=ζ
1
〈ζ|λ〉
N(λ, λ̃)
D(λ, λ̃)=
N(ζ, ζ̃)
D(ζ, ζ̃)
Spinor integration: residue extraction rules
Simple pole 〈λ|ζ〉:
Resλ=ζ
1
〈ζ|λ〉
N(λ, λ̃)
D(λ, λ̃)=
N(ζ, ζ̃)
D(ζ, ζ̃)= −Res
λ=ζ
1
〈λ|ζ〉
N(λ, λ̃)
D(λ, λ̃)(15)
Multiple pole 〈λ|ζ〉k:
Resλ=ζ
1
〈ζ|λ〉kN(λ, λ̃)
D(λ, λ̃)=
1
〈η|ζ〉k−1
{
1
(k − 1)!
d(k−1)
dt(k−1)
N(ζ − tη, ζ̃)
D(ζ − tη, ζ̃)
}∣
∣
∣
∣
t=0
(16)
Composite pole 〈λ|K|q]:
〈ζ| = [q|K| |ζ〉 = −|K|q]
[ζ̃| = −〈q|K| |ζ̃] = |K|q〉(17)
Spinor integration: bubble coefficients
Cut =
∫
λ̃=λ̄
〈λdλ〉 [λ̃dλ̃] Ispinor
Cbub=4
(4π)d2 i
∑
residues
1
(n−k)!
d(n−k)
ds(n−k)
1
sln
(
1 + s〈λ|q|λ̃]
〈λ|K|λ̃]
)
×
[
Ispinor〈λ|K|λ̃]n−k+2
〈λ|K|q|λ〉
∣
∣
∣
∣
|λ̃]=|K+sq|λ〉
]∣
∣
∣
∣
s=0
(18)
(n − k) is the difference between the numbers of λ-factors in the numerator and the
denominator of Ispinor, excluding the homogeneity-restoring factor 〈λ|K|λ̃]n−k+2
Spinor integration: propagators rewritten
(l1 −Ki)2 = K2 〈λ|Qi|λ̃]
〈λ|K|λ̃], (19)
Qµi (Ki,K) = −Kµ
i +K2
i
K2Kµ (20)
Spinor integration: triangle coefficients
Cut =
∫
λ̃=λ̄
〈λdλ〉 [λ̃dλ̃] Ispinor
Ctrii =
2
(4π)d2 i
1
(K2(xi+ − xi−)2)n−k+1
×1
(n−k+1)!
d(n−k+1)
dt(n−k+1)Ispinor 〈λ|Qi|λ̃] 〈λ|K|λ̃]n−k+2
{∣
∣
∣
∣ λ=λi+−tλi
−
λ̃=xi+λ̃i
−−txi−λ̃i
+
+
∣
∣
∣
∣ λ=λi−−tλi
+
λ̃=xi−λ̃i
+−txi+λ̃i
−
}∣
∣
∣
∣
t=0
,
(21)
P i±(Ki,K) = Qi + xi±K, (22)
xi± =−K ·Qi ±
√
(K ·Qi)2 −K2Q2i
K2. (23)
Spinor integration: box coefficients
Cut =
∫
λ̃=λ̄
〈λdλ〉 [λ̃dλ̃] Ispinor
Cboxij = −
2K2
(4π)d2 iIspinor 〈λ|Qi|λ̃] 〈λ|Qj |λ̃]
{∣
∣
∣
∣λ=λij+
λ̃=λ̃ij−
+
∣
∣
∣
∣λ=λij−
λ̃=λ̃ij+
}
,
(24)
P ij± (Ki,Kj ,K) = Qi + xij±Qj, (25)
xij± =−Qi ·Qj ±
√
(Qi ·Qj)2 −Q2iQ
2j
Q2j
. (26)
Simplest NMHV bubbles: MHV-MHV
l11−
. . .
p+
. . .
k− l2 (k+1)+
. . .
m−
. . .
n+
∑
h1,h2
A1A2 =(−1)ki[l1p]
2[l2p]2
[l11][12] . . . [k−1|k][kl2][l2l1]
×i 〈l1m〉2 〈l2m〉2
〈l2|k+1〉 〈k+1|k+2〉 . . . 〈n−1|n〉 〈nl1〉 〈l1l2〉
×
(
−[l1p] 〈l1m〉
[l2p] 〈l2m〉+ 2−
[l2p] 〈l2m〉
[l1p] 〈l1m〉
)
(27)
Simplest NMHV bubbles: MHV-MHV
∑
h1,h2
A1A2 =(−1)k 〈m|P1k|p]
2
P 21k[12] . . . [k−1|k] 〈k+1|k+2〉 . . . 〈n−1|n〉
×〈l1m〉 〈l2m〉 [l1p][l2p]
〈l1n〉 〈l2|k+1〉 [l11][l2k]
≡F
P 21k
〈l1m〉 〈l2m〉 [l1p][l2p]
〈l1n〉 〈l2|k+1〉 [l11][l2k]
=F
P 21k
〈l1m〉 〈l1|P1k|p] 〈m|P1k|l1][pl1]
〈l1n〉 〈l1|P1k|k] 〈k+1|P1k|l1][1l1]
(28)
Cut(P1k) =−F
4
∫
λ̃=λ̄
〈λdλ〉 [λ̃dλ̃]
〈λ|P1k|λ̃]2〈λ|m〉 〈λ|P1k|p] 〈m|P1k|λ̃][p|λ̃]
〈λ|n〉 〈λ|P1k|k] 〈k+1|P1k|λ̃][1|λ̃].
(29)
Simplest NMHV bubbles: MHV-MHV
Cbub,P1kN=1 chiral =−
F
(4π)d2 i
∑
residues
1
sln
(
1 + s〈λ|q|λ̃]
〈λ|P1k|λ̃]
)
×
{
〈λ|m〉 〈λ|P1k|p] 〈m|P1k|λ̃][p|λ̃]
〈λ|n〉 〈λ|P1k|k] 〈k+1|P1k|λ̃][1|λ̃]
×1
〈λ|P1k|q|λ〉
∣
∣
∣
∣
|λ̃]=|P1k+s q|λ〉
}∣
∣
∣
∣
s=0
(30)
Cbub,P1kN=1 chiral =
F
(4π)d2 i
∑
residues
[q|λ̃]
〈λ|P1k|λ̃]
×〈λ|m〉2 〈λ|P1k|p]
2
〈λ|k+1〉 〈λ|n〉 〈λ|P1k|1] 〈λ|P1k|k] 〈λ|P1k|q]
(31)
Simplest NMHV bubbles: MHV-MHV
Cbub,P1kN=1 chiral =
(−1)k
(4π)d2 i
〈m|P1k|p]2
[12] . . . [k−1|k] 〈k+1|k+2〉 . . . 〈n−1|n〉
×
{
〈m|k+1〉2 〈k+1|P1k|p]2[k+1|q]
〈k+1|n〉 〈k+1|P1k|1] 〈k+1|P1k|k] 〈k+1|P1k|k+1] 〈k+1|P1k|q]
+〈mn〉2 〈n|P1k|p]
2[nq]
〈n|k+1〉 〈n|P1k|1] 〈n|P1k|k] 〈n|P1k|n] 〈n|P1k|q]
+1
P 21k
(
[1p]2
[1k][1q]
〈m|P1k|1]2 〈1|P1k|q]
〈1|P1k|1] 〈k+1|P1k|1] 〈n|P1k|1]
+[kp]2
[k1][kq]
〈m|P1k|k]2 〈k|P1k|q]
〈k|P1k|k] 〈k+1|P1k|k] 〈n|P1k|k]
+[pq]2
[1q][kq]
〈m|P1k|q]2
〈k+1|P1k|q] 〈n|P1k|q]
)}
.
(32)
N = 1 chiral bubble formula
only simple poles:
CbubN=1 chiral = −
K2
(4π)d2 i
∑
residues
[λ̃|q]
〈λ|K|λ̃] 〈λ|K|q]
[
∑
h1,h2
A1A2
∣
∣
∣
∣
|λ̃]=|K|λ〉
]
.
(33)
a close analogue found byElvang,Huang,Peng
’11 [12]
Cut construction: NMHV double cut
l11+. . .
m−1
. . .m−
2
. . . k+ l2 (k+1)+
. . .
m−3
. . .
n+
Two-mass-easy quadruple cut
l11+. . .
m−1
. . .m−
2
. . .k+ l2 (k+1)+
. . .
m−3
. . .
n+
⇒
l11+. . .m−
1
. . .m−
2
. . .k+l2
(k+1)+l3 (k+2)+. . . m−
3
. . .
(n−1)+
l4
n+
NMHV super-amplitude in N = 4 SYM
fromDrummond,Henn,Korchemsky,Sokatchev
’08 [13]
ANMHVn = AMHV
n
r+n−3∑
s=r+2
r+n−1∑
t=s+2
Rrst, (34)
R = {r + 1, . . . , s− 1}
S = {s, . . . , t− 1}
T = {t, . . . , r − 1}
R S
Tr
s
t
r+1
r−1
s−1
t−1
Rrst =−〈s−1|s〉 〈t−1|t〉
P 2S 〈s−1|PS |PT |r〉 〈s|PS |PT |r〉 〈t−1|PS |PR|r〉 〈t|PS |PR|r〉
(35)
NMHV amplitudes
GGT package byDixon,Henn,Plefka,Schuster
’10 [14]:
Atree(1+g ,+. . ., a−g ,
+. . ., b−g ,+. . ., n−
g )
=i
〈12〉 〈23〉 . . . 〈n1〉
n−3∑
s=2
n−1∑
t=s+2
RnstD4nst;ab, (36a)
Atree(1+g ,+. . ., a−A
Λ , +. . ., b+BCDΛ , +. . ., c−g ,
+. . ., n−g )
=iǫABCD
〈12〉 〈23〉 . . . 〈n1〉
n−3∑
s=2
n−1∑
t=s+2
RnstD3nst;acDnst;bc, (36b)
Atree(1+g ,+. . ., aAB
S , +. . ., bCDS , +. . ., c−g ,
+. . ., n−g )
=iǫABCD
〈12〉 〈23〉 . . . 〈n1〉
n−3∑
s=2
n−1∑
t=s+2
RnstD2nst;acD
2nst;bc, (36c)
Double cut expression
l11+. . .
m−1
. . .m−
2
. . .k+ l2 (k+1)+
. . .
m−3
. . .
n+
∑
h1,h2
A1A2 =i 〈−l2|m3〉
2 〈l1|m3〉2
〈−l2|k+1〉 〈k+1|k+2〉 . . . 〈n−1|n〉 〈n|l1〉 〈l1|−l2〉
×i
〈−l1|1〉 〈12〉 . . . 〈k−1|k〉 〈k|l2〉 〈l2|−l1〉
×m1−3∑
s=m1+2
m1−1∑
t=s+2
Rm1stD2m1st;m2(−l1)
D2m1st;m2l2
×
(
〈−l2|m3〉Dm1st;m2(−l1)
〈l1|m3〉Dm1st;m2l2
+ 2 +〈l1|m3〉Dm1st;m2l2
〈−l2|m3〉Dm1st;m2(−l1)
)
(37)
Double cut expression
l11+. . .
m−1
. . .m−
2
. . .k+ l2 (k+1)+
. . .
m−3
. . .
n+
∑
h1,h2
A1A2 = −1
〈12〉 . . . 〈k−1|k〉 〈k+1|k+2〉 . . . 〈n−1|n〉
×〈l1|m3〉 〈m3| −l2〉
〈l1|1〉 〈l1|n〉 〈l1|l2〉2 〈k|l2〉 〈k+1|l2〉
×m1−3∑
s=m1+2
m1−1∑
t=s+2
Rm1stDm1st;m2(−l1)Dm1st;m2l2
×(
〈−l2|m3〉Dm1st;m2(−l1) + 〈l1|m3〉Dm1st;m2l2
)2
(38)
The factor which defines the non-zero cases for s and t
Dm1st;m2l2
=
〈m1|l2〉 〈m1|Pm1+1,s−1|Ps,t−1|m2〉 if {s, t} ∈ A
−P 2s,t−1 〈m1|m2〉 〈m1|l2〉 if {s, t} ∈ B
〈m2|l2〉(
〈m1|Pm1+1,s−1|l1] 〈l1|m1〉 − 〈m1|Pm1+1,s−1|P1,m1−1|m1〉)
if {s, t} ∈ C
− 〈m1|m2〉(
〈m1|l1〉 [l1|Ps,k |l2〉 − 〈m1|P1,m1−1|Ps,k|l2〉)
if {s, t} ∈ D
〈m2|l2〉 〈m1|Pt,m1−1|Pm1+1,s−1|m1〉 if {s, t} ∈ E
− 〈m1|m2〉 〈m1|Pt,m1−1|Pt,s−1|l2〉 if {s, t} ∈ F
0 otherwise,
(39)
Non-zero cases for s and t
A : s ∈ {m1+2, . . . ,m2}, t ∈ {m2+1, . . . , l2} (40a)
B : s ∈ {m2+1, . . . , k−1}, t ∈ {m2+3, . . . , l2} (40b)
C : s ∈ {m1+2, . . . ,m2}, t = −l1 (40c)
D : s ∈ {m2+1, . . . , k}, t = −l1 (40d)
E : s ∈ {m1+2, . . . ,m2}, t ∈ {1, . . . ,m1−1} (40e)
F : s ∈ {m2+1, . . . , l2}, t ∈ {1, . . . ,m1−1}. (40f)
Cases in s and tm1+4 . . . m2+1m2
m2
m1+2
m2+1
.
.
.
m2+2 m2+3 . . . . . .
.
.
.
.
.
.
k l2 −l1 1 m1−1
m1−3
1
−l1
l2
k
k−1
k−2
ts
A
B
C
D
E
F
Results: Frame formulas for generic bubbles and
2me-boxes
Cbub,P1kN=1 chiral(m
−1 ,m
−2 ∈{1, . . . , k},m−
3 ∈ {k+1, . . . ,n})
=∑
{s,t}∈A
Rs,tA +
∑
{s,t}∈B
Rs,tB +
∑
{s,t=−l1}∈C
RsC
+∑
{s,t=−l1}∈D
RsD +
∑
{s,t}∈E
Rs,tE +
∑
{s,t}∈F
Rs,tF
(41)
Cbox,2meN=1 chiral(m
−1 ,m
−2 ∈{1, . . . , k},m−
3 ∈ {k+1, . . . , n})
=∑
{s,t}∈A
Cbox,s,tA +
∑
{s,t}∈B
Cbox,s,tB +
∑
{s,t=−l1}∈C
Cbox,sC
+∑
{s,t=−l1}∈D
Cbox,sD +
∑
{s,t}∈E
Cbox,s,tE +
∑
{s,t}∈F
Cbox,s,tF
(42)
Example: simpler bubbles
only case F contributes to:
l11+
. . .
(k−2)+
(k−1)−
k− l2 (k+1)+
. . .
m−
. . .
n+
Simpler bubble coefficients
l11+
. . .(k−2)+(k−1)−
k− l2 (k+1)+
. . .
m−
. . .
n+
Cbub,P1kN=1 chiral
=P 21k
(4π)d2 i
∑
residues
[q|λ̃]
〈λ|P1k|λ̃]
{
F1〈λ|m〉2 〈λ|P1k|P1,k−1|k−1〉
〈λ|k+1〉 〈λ|n〉 〈λ|P1k|k] 〈λ|P1k|q]
+k−2∑
t=2
Ft 〈t−1|t〉
〈t−1|Pt,k|k]
〈λ|m〉2 〈λ|Pt,k|Pt,k−1|k−1〉
〈λ|1〉 〈λ|k+1〉 〈λ|n〉 〈λ|P1k|q]
}
,
(43)
Ft =〈m|Pt,k|Pt,k−1|k−1〉2
P 2t,k−1P
2t,k 〈t|Pt,k|k]
(44)
Results: simpler bubble coefficients
Cbub,P1kN=1 chiral =
1
(4π)d2 i
1
〈12〉 . . . 〈k−2|k−1〉 〈k+1|k+2〉 . . . 〈n−1|n〉
×
{ k−2∑
t=2
⟨
m|Pt,k|Pt,k−1|k−1⟩2
〈t−1|t〉
P 2t,kP
2t,k−1 〈t−1|Pt,k|k] 〈t|Pt,k|k]
(
〈m|P1k |k+1|m〉⟨
k+1|Pt,k|Pt,k−1|k−1⟩
〈k+1|1〉 〈k+1|n〉 〈k+1|P1k|k+1]
+〈m|P1k|1|m〉
⟨
1|Pt,k|Pt,k−1|k−1⟩
〈1n〉 〈1|k+1〉 〈1|P1k|1]+
〈m|P1k|n|m〉⟨
n|Pt,k|Pt,k−1|k−1⟩
〈n1〉 〈n|k+1〉 〈n|P1k|n]
)
+
⟨
m|P1k|P1,k−1|k−1⟩2
P 21kP
21,k−1 〈1|P1k|k]
(
〈m|P1k|k+1|m〉⟨
k+1|P1k|P1,k−1|k−1⟩
〈k+1|n〉 〈k+1|P1k|k] 〈k+1|P1k|k+1]
+〈m|P1k|n|m〉
⟨
n|P1k|P1,k−1|k−1⟩
〈n|k+1〉 〈n|P1k|k] 〈n|P1k |n]+
P 21k 〈m|P1k|k|m〉 〈k−1|P1k|k]
〈n|P1k |k] 〈k+1|P1k|k] 〈k|P1k|k]
)}
(45)
Massive poles
l1· · · 1+m−1
. . .(i−1)+
i+. . .m−
2· · · k+ l2 (k+1)+
. . .
m−3
. . .
n+
(l1 − P1,i)2 = P 2
1k
〈λ|Qi|λ̃]
〈λ|P1k|λ̃](46)
〈λ|Qi|P1k|λ〉 = −
⟨
λ|λi+
⟩
[λ̃i+|λ̃
i−]⟨
λi−|λ⟩
xi+ − xi−(47)
Resλ=λi
±
F (λ, λ̃)
〈λ|P1k|λ̃] 〈λ|Qi|P1k|λ〉= −
F (λi±, λ̃
i±)
4(
(P1,i−1 · Pi,k)2 − P 21,i−1P
2i,k
)
(48)
Results: sample contribution
for s ∈ {m1+3, . . . , m2}, t = −l1
RsC
=−P21k
(4π)d2 i
〈s−1|s〉
〈12〉 . . . 〈k−1|k〉〈k+1|k+2〉 . . . 〈n−1|n〉
{
F sC(λ1, λ̃1)
〈1|k〉〈1|k+1〉〈1|n〉+
F sC(λk, λ̃k)
〈k|1〉〈k|k+1〉〈k|n〉
+F sC(λk+1, λ̃k+1)
〈k+1|1〉〈k+1|k〉〈k+1|n〉+
F sC(λn, λ̃n)
〈n|1〉〈n|k〉〈n|k+1〉+
〈m1|P1k|q]2 〈m2|P1k|q]2 〈m3|P1k|q]2
P41k
〈1|P1k|q] 〈k|P1k|q] 〈k+1|P1k|q] 〈n|P1k|q]
×〈m1|Pm1+1,s−1|q]
2
[q|P1,s−1|Ps,k|q] 〈m1|Pm1+1,s−1|P1,s−1|P1k|q] 〈m1|Pm1+1,s−1|Ps,k|P1k|q]
×(
P21k 〈m3|m1〉 〈m2|P1k|q] 〈m1|Pm1,s−1|q] + 〈m1|m2〉 〈m3|P1k|q] 〈m1|Pm1,s−1|Ps,k|P1k|q]
)2
/(
(
〈m1|s−1〉 [q|P1,m1|Pm1+1,k|q] + 〈m1|P1k|q] 〈s−1|Pm1+1,s−2|q]
)
×(
〈m1|s〉 [q|P1,m1|Pm1+1,k|q] + 〈m1|P1k|q] 〈s|Pm1+1,s−1|q]
)
)
+MsC(λ
+s , λ̃
+s ) + M
sC(λ
−
s , λ̃−
s )
}
,
FsC(λ, λ̃) =
〈λ|m1〉2 〈λ|m2〉
2 〈λ|m3〉2⟨
λ|P1k|Pm1+1,s−1|m1
⟩2[λ̃|q]
⟨
λ|P1,s−1|Ps,k|λ⟩
⟨
λ|P1,s−1|Pm1+1,s−1|m1
⟩ ⟨
λ|Ps,k|Pm1+1,s−1|m1
⟩
〈λ|P1k|λ̃] 〈λ|P1k|q]
×(
〈λ|m2〉 〈m3|m1〉⟨
m1|Pm1+1,s−1|P1k|λ⟩
+ 〈λ|m3〉 〈m1|m2〉⟨
m1|Pm1+1,s−1|Ps,k|λ⟩
)2
/(
(
〈m1|s−1〉⟨
λ|P1,m1|Pm1+1,k|λ
⟩
+ 〈λ|m1〉⟨
λ|P1k|Pm1+1,s−2|s−1⟩
)
(
〈m1|s〉⟨
λ|P1,m1|Pm1+1,k|λ
⟩
+ 〈λ|m1〉⟨
λ|P1k|Pm1+1,s−1|s⟩
)
)
Results: sample contribution
for s ∈ {m1+3, . . . , m2}, t = −l1
RsC
=−P21k
(4π)d2 i
〈s−1|s〉
〈12〉 . . . 〈k−1|k〉〈k+1|k+2〉 . . . 〈n−1|n〉
{
F sC(λ1, λ̃1)
〈1|k〉〈1|k+1〉〈1|n〉+
F sC(λk, λ̃k)
〈k|1〉〈k|k+1〉〈k|n〉
+F sC(λk+1, λ̃k+1)
〈k+1|1〉〈k+1|k〉〈k+1|n〉+
F sC(λn, λ̃n)
〈n|1〉〈n|k〉〈n|k+1〉+
〈m1|P1k|q]2 〈m2|P1k|q]2 〈m3|P1k|q]2
P41k
〈1|P1k|q] 〈k|P1k|q] 〈k+1|P1k|q] 〈n|P1k|q]
×〈m1|Pm1+1,s−1|q]
2
[q|P1,s−1|Ps,k|q] 〈m1|Pm1+1,s−1|P1,s−1|P1k|q] 〈m1|Pm1+1,s−1|Ps,k|P1k|q]
×(
P21k 〈m3|m1〉 〈m2|P1k|q] 〈m1|Pm1,s−1|q] + 〈m1|m2〉 〈m3|P1k|q] 〈m1|Pm1,s−1|Ps,k|P1k|q]
)2
/(
(
〈m1|s−1〉 [q|P1,m1|Pm1+1,k|q] + 〈m1|P1k|q] 〈s−1|Pm1+1,s−2|q]
)
×(
〈m1|s〉 [q|P1,m1|Pm1+1,k|q] + 〈m1|P1k|q] 〈s|Pm1+1,s−1|q]
)
)
+MsC(λ
+s , λ̃
+s ) + M
sC(λ
−
s , λ̃−
s )
}
,
MsC(λ, λ̃) = −
1
4((P1,s−1 · Ps,k)2 − P2
1,s−1P2s,k
))
×〈λ|m1〉
2 〈λ|m2〉2 〈λ|m3〉
2⟨
λ|P1k|Pm1+1,s−1,m1
⟩2[λ̃|q]
〈λ|1〉 〈λ|k〉 〈λ|k+1〉 〈λ|n〉⟨
λ|P1,s−1|Pm1+1,s−1|m1
⟩ ⟨
λ|Ps,k|Pm1+1,s−1|m1
⟩
〈λ|P1k|q]
×(
〈λ|m2〉 〈m3|m1〉⟨
m1|Pm1+1,s−1|P1k|λ⟩
+ 〈λ|m3〉 〈m1|m2〉⟨
m1|Pm1+1,s−1|Ps,k|λ⟩
)2
/(
(
〈m1|s−1〉⟨
λ|P1,m1|Pm1+1,k|λ
⟩
+ 〈λ|m1〉⟨
λ|P1k|Pm1+1,s−2|s−1⟩
)
(
⟨ ⟩ ⟨ ⟩
)
)
Checks
1. Check the sum of all bubbles through for 6,7 and 8 points:
∑
Cbub =1
(4π)d2
Atree
2. NGluon byBadger,Biedermann,Uwer
’10 [15]
Numerical data kindly produced by Simon Badger:gluon, fermion and scalar loop contributions for 6-25 ext. gluonsA(1−, 2−, 3+, 4−, 5+, 6+, . . . , n+) andA(1−, 2+, 3−, 4+, 5+, 6−, . . . , n+).Agreement up to 13 digits for 8 points and 12 digits for 17points.
Conclusions
1. New one-loop amplitudes are known analytically for all n.
2. Good tree formulas ⇒ new loop results.
3. NMHV in N = 1 SYM: untrivial both in helicities and susy.
4. Mathematica files are distributed:N1chiralAll.nb, Ammppmppp.nb.
5. Everybody is invited to play!
Outlook: one-loop recursion
+ −
7+
l1
1−
2−3+l2 4̂−
5̂+
6+P̂5,6
=
7+
l1
1−
2−3+l2
4−
5+
6+
Thank you for listening!
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