Quasiparticle interference in the pseudogap phase of cuprate ...

QP INTERFERENCE 12
Nodal approximation: importance of coherence factors
One finds
Λ(q, iω) = 1 L 2 ∑
k
(iω + ɛ + )(iω + ɛ − ) − ∆ + ∆ −
(ω 2 + E+)(ω 2 2 + E−)
2 ,
k
y
with ɛ ± = ɛ
√ k±q/2 , ∆ ± = ∆ k±q/2
and E ± = ɛ 2 ± + ∆ 2 ±. Linearize
near the nodes to obtain
v
−
F
v∆
Q’
Q
+
v
∆
v
F
−
k 2 k 1
k
x
v
F
v
∆
+
v
∆
v
F
Λ lin = 1
v F v ∆
∫
d 2 k
(2π) 2 −ω 2 + (k 2 1 − k 2 2) − (˜q 2 1 − ˜q 2 2)
[ω 2 + (k + ˜q) 2 ][ω 2 + (k − ˜q) 2 ] .
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