-44-
접선벡터 좌표계를 사용한 열핵 전개 II
이해원*
충북대학교 물리학과, 청주 361-763 (2009년 12월 3일 받음)
d/2 개의 2계 타원 미분 연산자들의 곱으로 만들어진 d-계 타원연산자의 열핵(heat kernel) 전개를 연구하였다. 일반적인 차원 n을 갖는 굽어진 시공간에서 계산을 수행하였다. 열핵 전개의 처음 두 항들을 계산하였는데 그 결과는 각 2계 연산자의 경우에 얻어진 항들을 단순히 더한 것과 같지 않고 추가적인 항 들이 존재하게 된다. 이러한 계산을 위하여 좌표변환의 공변성을 유지하면서 접선벡터좌표계를 사용하는 방 법을 사용하였다.
핵심어: 열핵, 타원연산자, 접선벡터
_______________________________________________________________________________
Heat Kernel Expansions Using Tangent Vector Coordinate Systems II
Haewon LEE*
Department of Physics, Chungbuk National University, Cheongju 361-763 (Received 3 December 2009)
Heat kernel expansions of the d-th order elliptic operators obtained by using a product of d/2 second order elliptic operators in curved space-time with dimension n are investigated. We calculate the first two coefficient functions of the expansions, which are not the simple sum of the coefficients for each second order elliptic operator. For the calculations, we use a method with a tangent vector coordinate system, with which our calculatins are manifestly covariant under coordinate and gauge transformations.
Keywords: Heat Kernel, Elliptic Operator, Tangent Vector PACS numbers: 03.70.+k, 04.62.+v, 11.10.+z
* E-mail: hwlee@hep.chungbuk.ac.kr
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.
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¦>íß_ âĺ\¸ x0= x âĺ\HAü< °ú s
>h 0px [3].
hxτ |xi = 1 τn/d
a0(x) + a1(x)τ2/d+ a2(x)τ4/d+ · · · , (3) a0, a1, 1pxÉr ×æ§4 J$"f gµν,>st© AµÕªo¦ Õª ü@ _
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x _ J$"f '§>= <Êús. íß_ order d s
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.
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360XνλβξRµλνRξδβ ∂
∂Xδ
+O(X5). (7)
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+1
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+1
24Xνλδξ∇ξ∇δ∇λ∇νφµ+ O(X5). (8)
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∂
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. (9)
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<Êú aα···βµ···ν _ |9|¾Ó "é¶Dim(a)s 0 ½Ós Ð Mx(0) s.
Mx(0) _ \PÙþÉr ~1> >íß½+É Ãº e.
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2τd2), (10)
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6 xôÇ.
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2τ2d), (11)
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ñ)a. mx H Campbell-Hausdorf /BNd`¦6 x # > í
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∂Xν Φ(X2
2 ). (13)
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Φ(X2 2 ) =
Z dnp
(2π)neipµXµ−(p2)d/2. (14)
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X→0lim
∂
∂Xµ1 · · · ∂
∂Xµ2j Φ(X2 2 )
= 1 Cj
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`¦ Ð{9 ú e. 0A\"f Cj = 2jQj
i=1(n2 + i − 1) s
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H J$"fs.
gµ1···µk=
k
X
j=2
gµ1µjgµ2···µj−1µj+1···µk . (16)
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s
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.
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Mx= Mx(0)+ Mx(2)+ Mx(3)+ Mx(4)· · · (17) 0
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mx= m(2)x + m(3)x + m(4)x · · · (18)
)a. :r>íß\"fH Mx(3)ü< m(3)x H>íßõ\ %ò¾Ó
`
¦ÅÒt ·ú§l\ ÁºrK¸)a. m(2)x ü< m(4)x \¦ Hausdorf /
BNd`¦6 x # ½¨ 6£§õ °ú .
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1 + L
2
Mx(2) (19)
m(4)x =
1 + L
2 +L2 6 +L3
24
Mx(4)− 1 12
h
Mx(2), LMx(2)i
#
l"f L ≡ [−Mx(0), ]Ð+ \V\¦ [þt LA = [− fM0, A]s¦ L2A = [−Mx(0), [−Mx(0), A]]s. 0A d\
"
f k ≥ j {9 M: LkMx(j)= 0 $í|9`¦6 x %i. ôǼ# d
(12) ܼÐÂÒ' >h >ú a0, a1 Õªo¦ a2 H6£§õ
° ú
s jþtú e.
a0(x) = lim
X→0Φ a1(x) = lim
X→0
−m(2)x Φ a2(x) = lim
X→0
1
2m(2)x m(2)x − m(4)x
Φ (20) m(2)x ü< m(4)x _ ³ð&³`¦%3l 0AK 2> íß ∇2+ Ck
\
¦6£§õ °ú s ?/.
∇2+ Ck = A + (B + Ck) + (D + Fk), (21) 0
A\"f A = ∂2 B = −1
3Xτ ρ∂αβRαρβτ−2
3Xτ∂αRατ + Xτ∂αΩτ α
D = Xτ ρηξ∂αβ
−1
20Rβρατ ;ηξ+ 1
15RβρστRσξαη
+Xτ ρη∂α
−3
20Rατ ;ρη+ 4
25Rβτ σρRσηαβ
+1
4Xτ ρΩτ σΩρσ Fk = 1
2Xτ ρCk;τ ρ. (22)
d
`¦ çßéß > æ¼l0AK ∂X∂α· · ·∂X∂β \¦ ∂α···β Ð ³ðl
%i. ¢¸ôÇ J$"f ³ð&³\"f ”;” \¦ØÔH 'H /BN p
ìr`¦_pôÇ. \V\¦ [þt#Q Ck;τ ρ= ∇ρ∇τCk \¦_pôÇ
. ¢¸ôÇ Ωαβ ≡ [∇α, ∇β] s. 0A_ ½Ó[þt\"f A _ |9
|
¾Ó "é¶Ér 0, Bü< CkH 2 ,Õªo¦ Dü< Fk H 4s.
d
(22) _ &ñ_\¦ 6 x # Mx ≡Qd/2
k=1(−∇2− Ck)
\
¦ d (17)õ °ú s >h 6£§õ °ú .
Mx(0) = (−1)dAd Mx(2) = (−1)dX
k
[BAd−1+ (k − 1)GAd−2+ CkAd−1] LMx(2) = −d2GA2d−2
Mx(4) = (−1)dX
k
[Ak−1DAd−k+ Ak−1FkAd−k] +(−1)d X
k0>k
[B2Ad−2+ (k − 1)GBAd−3
+(k0− 2)BGAd−3+ (k − 1)(k0− 3)G2Ad−4 +CkBAd−2+ BCkAd−2+ CkCk0Ad−2 +(k − 1)GCk0Ad−3+ (k0− 2)GCkAd−3] (23)
#
l"f G = [A, B] = −23∂αβRαβ s¦ d = d2s.
d
(20) \¦6 x # a1õ a2\¦>íß HX< Aü< °ú
É
r>íß`¦ÅÒ >)a.
lim
X→0(∂2)iXα1···αp∂γ1···γq(∂2)jΦ (24) s
_ >íß õHAü< °ú s כ¹|¨cú e.
[p/2]
X
r=0
S2rpq(i, j)gα2r1···αp;γ1···γq, (25)
#
l"f g2rα1···αp;γ1···γq H 6£§õ °ú s &ñ_)a J$"fs¦ S2rpq(i, j)HÕª_ >ús.
g2rα1···αp;γ1···γq ≡ gα1α2gα3α4· · · gα2r−1α2rgα2r+1···γq + gα1α3gα2α4· · · gα2r−1α2rgα2r+1···γq+ · · ·
¢
¸ôÇ S2rpq(i, j) H6£§õ °ú .
S2rpq(i, j) = i!
(i − p + r)!
2p−r Cp+q
2 −r
×(−1)i+j+q−p2 Γ(n+2i+2j+q−p
d )
(4π)n2d2 Γ(n2) (26)
#
l"f i ≥ p − r ≥ r s âĺH 0_ °úכ`¦°úH.
S2rpq(i, j)\¦ iü< j \'a> H<ÊúР:r
Xα1···αp∂γ1···γq ∼
[p/2]
X
r=0
S2rpqg2rα1···αp;γ1···γq (27)
ü
< °ú s jþt ú e`¦ כ s. ôǼ# d (26) \"f Spq2r = S2r−2s(p−s)(q−s)e`¦Ð{9 ú e. ¢¸ôÇ ·ú¡Ü¼ÐH Spq≡ Spq0
Ð ³ðl½+É כ s.
d
(27)`¦6 x >íßõ #Q" J$"f[þt_ ½+Ët p
o f½+É Ãº e. Óüt:ry J$"f_ >úH S2rpq\ (i, j)
° ú
כ`¦ @/{9K ·ú ú e. >íß\ 1px© H#Q ª[þt
\
@/K s\¦&h6 x # Ð 6£§õ °ú .
B ∼ −1 3S11R G ∼ −2
3S02R D ∼ −1
5(S20+ S31)R;ββ− 1
45(S31+ S20)(RαβRαβ +3
2RαβγδRαβγδ) +1
4(S20+ S220)ΩαβΩαβ B2 ∼ 1
9S22R2+2
9(S22+ S11)RαβRαβ GB ∼ 2
9S13(2RαβRαβ+ R2) +4
9S02RαβRαβ BG ∼ 2
9S13(2RαβRαβ+ R2) G2 ∼ 4
9S04(2RαβRαβ+ R2) Fk ∼ 1
2(S20+ S220)Ck;ββ (28) 0
A_ d[þt`¦6 x # >ú a1, a2 Õªo¦ a3 \¦½¨½+É Ã
º eHX< õ\¦&ño 6£§õ °ú .
a0 = Γ(nd) (4π)n2d2 Γ(n2) a1 = Γ(n+d−2d )
(4π)n2d2 Γ(n2) X
k
( 2
3nR + Ck) a2 = Γ(n+d−4d )
(4π)n2d2 Γ(n2)[X
k
(n − 2)( 1
60R;αα+ 1 144R2
− 1
360RαβRαβ+ 1
360RαβγδRαβγδ+ 1
24ΩαβΩαβ) +X
k
(1
6+(n − 4)(n + d)
48 )RCk+1 2
X
k0>k
[Ck0, Ck]
+1 2
X
k
Ck2+n − 4 2d (X
k
Ck)2
+X
k
(n − 2
6 −f (d, k) 12n )Ck;αα] 0
A\"f f(d, k) = (d + 2)(d + 4 − 12k) + 24k2 Ð"f P
kf (d, k) = 0s.
IV. +sÇÂ]Ø
/
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õ
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כ
[þts #Qt extëß #l"fHª©:r\"f_
ü@µ1Ïíß(Ultra-violet divergence)ü<'aº)a ëH]j\ @/K
¶ ú
(RЦ ôÇ. õ\¦Ð a1_ âĺH d = 2_ õ
_ éßíH ½+Ëõ °ú . ÕªQ a2 _ âĺH ÕªXOt ·ú§
. [Ck0, Ck]s Ck;ααõ °ú Ér½Ó[þtÉrr/BNçßýa³ð\ @/ ô
Ç &hìrõ ?/ÂÒ/BNçß\ @/ôÇ ½+Ë`¦>íß \O#QtH½Ó [
þ
ts. sQôÇ divergence ½Ó[þt`¦]jü@ #¸ a2H d = 2 {9M: %3H õ_ éßíH ½+Ës m. n = 4 âĺ
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[1] B. S. DeWitt, Dynamical Theory of Groups and Fields (Gordan and Breach, New York, 1965); Phys.
Rep. 19C, 295(1975).
[2] A. O. Barvinsky and G. A. Vilkovisky, Phys. Rep.
119, 1(1985); and references therein.
[3] Haewon Lee, Pong Youl Park and Hyun Kuk Shin, Phys. Rev. D 35, 2440 (1987).
[4] Haewon Lee and Sang Won Lee, Sae Mulli 58, 654 (2009).