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Physics
Letters
B
www.elsevier.com/locate/physletb
An HHL
3-point
correlation
function
in
the
η
-deformed
AdS
5
×
S
5
Changrim Ahn
a,
b,
∗
,
Plamen Bozhilov
b,
caInstitutfürMathematik,InstitutfürPhysikand IRISAdlershof,Humboldt-UniversitätzuBerlin,ZumGroßenWindkanal6,12489Berlin,Germany bDepartmentofPhysics,EwhaWomansUniversity,DaeHyun11-1,Seoul120-750,RepublicofKorea
cInstituteforNuclearResearchandNuclearEnergy,BulgarianAcademyofSciences,Bulgaria
a
r
t
i
c
l
e
i
n
f
o
a
b
s
t
r
a
c
t
Articlehistory:
Received11January2015 Accepted13February2015 Availableonline18February2015 Editor:L.Alvarez-Gaumé
We derivethe 3-pointcorrelation functionbetween two giant magnons heavy stringstates and the light dilatonoperator with zero momentuminthe
η
-deformed AdS5×S5 validfor any J1 andη
inthe semiclassical limit. We show that thisresult satisfies aconsistencyrelation betweenthe 3-point correlationfunctionandtheconformaldimensionofthegiantmagnon.Wealsoprovidealeadingfinite
J1correctionexplicitly.
©2015TheAuthors.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3.
1. Introduction
TheAdS/CFTduality
[1]
betweenstringtheoriesoncurvedspace–times withanti-deSittersubspacesandconformalfieldtheoriesin differentdimensionshasbeenactively investigatedinthelastyears.Alotofimpressiveprogresshas beenmadeinthisfield ofresearch basedmainlyon theintegrability structuresdiscoveredon bothsidesofthe correspondence(forrecentreview onthe AdS/CFTduality, see [2]). Forthe most studied case of theN =
4 super Yang–Mills theory, the anomalous dimensions of gauge-invariant single-trace operatorsmatchnon-perturbativelywiththestringenergiesinthecurvedAdS5×
S5 background.Integrabilityprovidestoolstosolvethe finite-volumespectralproblemexactly.Afterthesesuccesses,onedirectionofinterestingdevelopment istogeneralizethedualitytolargertheorieswhichincludetheoriginal AdS/CFTasaspecialcaseandtheotheristogobeyondthespectralproblembycomputinggeneralcorrelationfunctions,inparticular,the three-pointfunctions,orthestructureconstants.
Aninteresting developmentfortheformerdirectionistostudythestringtheory onthe
η
-deformedAdS5×
S5 background[3]
.The bosonic part of the superstring sigma model Lagrangian on thisη
-deformed background and perturbative worldsheet S-matrix were obtainedin[4]
.The TBAforspectrum andexplicitdispersion relationforgiant magnon[5]
have beenderived in[6]
.Finite-size effect onthegiantmagnonspectrumhasbeencomputedin[7]
.Forthree-pointcorrelationfunctions,quitealotofinterestingresultsonboth strongandweakcouplingregionswereaccumulatedalthoughnon-perturbativeresultsaremuchmoredifficultthanthespectralproblem. Inthisletter,we computethethree-point correlationfunctionoftwo giantmagnonheavy operatorswithfinite-size J1 andasingle dilatonlightoperator ofthestringtheory withtheη
-deformedAdS5×
S5 background[3]
.Then,we show thatthisresultisconsistent withthedispersionrelationofthefinite-sizegiantmagnonsolutionobtainedin[7]
usingMathematicacode.Thepaperisorganizedasfollows.InSection2,wederivetheexactsemiclassicalstructureconstantvalidforany J1and
η
andproveits consistency.InSection3,weexpanditforthecaseof J1T (T isthetensionofstring)andobtainexplicitexpression.Abriefconclusion isinSection4andashortMathematicacodefortheconsistencyconditionisprovidedinAppendix A
.2. Exactsemiclassicalstructureconstant
Accordingto [8],the three-point functionsof two “heavy” operators anda “light” operatorcan be approximatedby a supergravity vertexoperatorevaluatedatthe“heavy”classicalstringconfiguration:
VH(x
1)V
H(x
2)V
L(x
3)
=
VL(x
3)
classical.
*
Correspondingauthor.E-mailaddresses:[email protected](C. Ahn),[email protected](P. Bozhilov). http://dx.doi.org/10.1016/j.physletb.2015.02.032
0370-2693/©2015TheAuthors.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).Fundedby SCOAP3.
For
|
x1|
= |
x2|
=
1,x3=
0,thecorrelationfunctionreducesto VH(x
1)V
H(x
2)V
L(
0)
=
C123
|
x1−
x2|
2H.
Then,thenormalizedstructureconstant
C
3=
C123
C12 canbefoundfrom
C
3=
cVL(
0)
classical,
(2.1)wherec isthenormalizedconstantofthe“light”vertexoperator.Actually,wearegoingtocomputethenormalizedstructureconstant
(2.1).Forthecaseunderconsideration,the“light”stateisrepresentedbythedilatonwithzeromomentum.
Accordingto
[9]
,C3fortheinfinite-sizegiantmagnonsanddilatonwithzeromomentumintheundeformedAdS5×
S5 isgivenbyC3
=
cd +∞ −∞ dτ
e cosh4(
κτ
e)
+∞ −∞ dσ
κ
2+ ∂
XK¯∂
XK=
4cd 3κ
+∞ −∞ dσ
κ
2+ ∂
XK¯∂
XK,
(2.2)wheret
=
κτ
e istheEuclidean AdS timeandtheterm∂
XK¯∂
XK isproportional tothe stringLagrangian on S2 computedonthe giantmagnonsolutionlivinginthe Rt
×
S2 subspace.Sincehereweareinterestedinfinite-size giantmagnons,wehavetoreplace
+∞
−∞ dσ
→
+L −L dσ
=
2 θmax θmin dθθ
,
whereL givesthesizeofthegiantmagnonand
θ
isthenon-isometricangleonthetwo-sphere[11]
.Goingtothe
η
-deformed AdS5×
S5 case, we haveto compute theterm∂
XK¯∂
XK forthisbackground,which isproportional to thestringLagrangianon S2η forfinite-size giantmagnons:
LS2 η
= −
T
2
∂
XK¯∂
XK,
where XK
= (φ
1,
θ )
aretheisometricandnon-isometricstringcoordinatesonS2η correspondingly.Workinginconformalgaugeandapplyingtheansatz
φ
1(
τ
,
σ
)
=
τ
+
F1(ξ ),
θ (
τ
,
σ
)
= θ(ξ), ξ =
ασ
+ β
τ
,
α
, β
−
constants,
onefinds LS2 η= −
T 2(
α
2− β
2)
θ
2 1+ ˜
η
2(
1−
χ
)
+ (
1−
χ
)
(
α
2− β
2)(
F 1)
2−
2β
F1−
1,
(2.3)where
η
˜
isrelatedtothedeformationparameterη
accordingto[4]
˜
η
=
2η
1
−
η
2,
(2.4)andanew variable
χ
isdefinedbyχ
=
cos2θ.
Theprimehereandbelowisaderivatived
/
dξ
.ThestringtensionT fortheη
deformedcaseisrelatedtothecouplingconstant g byT
=
g1
+ ˜
η
2.
(2.5)Thefirstintegralsoftheequationsofmotion F1 and
θ
canbewrittenasF1
=
β
α
2− β
2−
κ
2 1−
χ
+
1,
(2.6)θ
2=
1+ ˜
η
2(
1−
χ
)
(
α
2− β
2)
2(
α
2+ β
2)
κ
2−
β
2κ
4 1−
χ
−
α
2(
1−
χ
)
.
(2.7)Inserting
(2.6)
,(2.7)
into(2.3),weobtain:LS2 η
= −
T 2β
2κ
2+
α
2(
κ
2−
2(
1−
χ
))
α
2− β
2.
(2.8)Nowweintroducethenewparameters v
= −
β
α
,
W=
κ
2,
whichleadsto LS2 η= −
T 2(
1+
v2)W
−
2(
1−
χ
)
1−
v2.
(2.9)Therefore,forthecaseathand,thenormalizedstructureconstanttakestheform
Cη3˜
=
8c d 3√
W χp χm dχ
χ
W+
(
1+
v 2)W
−
2(
1−
χ
)
1−
v2,
(2.10) whereχ
m=
χ
min,
χ
p=
χ
max.
OnecanrewriteEq.(2.7)as
χ
=
2η
˜
1−
v2(
χ
η−
χ
)(
χ
p−
χ
)(
χ
−
χ
m)
χ
,
(2.11) where[7]
χ
m=
1−
W,
χ
p=
1−
v2W,
χ
η=
1+
1˜
η
2.
(2.12)Usingthis,wecanexpressalltheresultsintermsof
χ
p,
χ
m byeliminatingv,W .Replacing
(2.11)
in(2.10)andusing(2.12)
,wecanexpressC3η˜ byCη3˜
=
8c d 3η
˜
√
1−
χ
m χp χmχ
−
χ
m(
χ
η−
χ
)(
χ
p−
χ
)
χ
dχ
.
(2.13)TheintegralcanbeeasilyexpressedbyK and
,thecompleteellipticintegralsofthefirstandthethirdkind,respectively,areas follows:
Cη3˜
=
16c d 3η
˜
χ
mχ
p(
1−
χ
m)(
χ
η−
χ
m)
1
−
χ
mχ
p,
1−
−
K(
1−
)
,
(2.14)whereweintroducedashortnotation
by
=
χ
m(
χ
η−
χ
p)
χ
p(
χ
η−
χ
m)
.
(2.15)Eq.(2.14)isthemainresultofthispaper,whichisanexact semiclassicalresultforthenormalizedstructureconstantCη3˜ validforany value of
η
˜
and J1. Here,χ
p andχ
m are determined by theangularmomentum J1 andworld-sheet momentum p from the following equations1: J1=
2T˜
η
1χ
p(
χ
η−
χ
m)
χ
pK(
1−
)
−
χ
m1
−
χ
mχ
p,
1−
,
(2.16) p=
2χ
m˜
η
1−
χ
pχ
p(
1−
χ
m)(
χ
η−
χ
m)
K(
1−
)
−
χ
p−
χ
mχ
p(
1−
χ
m)
,
1−
.
(2.17)Theworld-sheetenergyofthegiantmagnonisgivenby
E
=
2T˜
η
χ
p−
χ
mχ
p(
1−
χ
m)(
χ
η−
χ
m)
K(
1−
) .
(2.18)Oneofnontrivialchecks isthat the g derivativeof
=
E−
J1 shouldbeproportionaltothenormalizedstructureconstantCη3˜ since the g derivativeof thetwo-point function insertsthe dilaton(Lagrangian) operatorintothe two-point functionof theheavy operators[10].Thiscanbeexpressedby
Cη3˜
=
8c d 31+ ˜
η
2∂
∂
g.
(2.19) 1 Weexpress JTocheckthatEqs.(2.14),
(2.16)
,and(2.18)
satisfyEq.(2.19),weusethefactthat∂
J1∂
g=
∂
p∂
g=
0 (2.20)asnoticedin
[11]
forthecaseofundeformedgiantmagnon.Fromthese,we canobtaintheexpressionsfor∂
χ
p/∂
g and∂
χ
m/∂
g whichcanbe insertedinto
∂/∂
g.Theη
-deformed caseinvolvesmuch morecomplicatedexpressionswhich canbe dealtwith Mathematica. InAppendix A
,we provideourMathematicacodewhichconfirmsthatthestructureconstant Cη3˜ inEq.(2.14) dosatisfy theconsistency condition(2.19)
exactly.Inthelimit
η
˜
→
0 withη
˜
2χη
→
1,Eq.(2.14)becomesC30
=
16c d 3χ
p 1−
χ
m [E(
1−
)
−
K
(
1−
)
],
=
χ
mχ
p (2.21)whereweusedthe identity
(
1−
a)(
a,
a)
=
E(
a)
.Thisisthestructureconstantoftheundeformedtheoryderivedin[11]
.3. Leadingfinite-sizeeffectonCη3˜
Itisstraightforward tocomputealeadingfinite-sizeeffectonC3η˜ for J1
g bythelimit→
0 in(2.14)
. Firstweexpandtheparametersχ
p,W andv forsmallasfollows:
χ
p=
χ
p0+ (
χ
p1+
χ
p2log)
,
W
=
1+
W1,
v
=
v0+ (
v1+
v2log)
.
(3.1)InsertingintoEq.(2.14),weobtain
C3η˜
≈
16c d 3η
˜
21+
1 ˜ η2χ
p0(
1+ ˜
η
2)
χ
p0arctanh˜
η
√
χ
p0 1+ ˜
η
2−
W1 2(
1+ ˜
η
2)
χ
p0arctanh˜
η
√
χ
p0 1+ ˜
η
2+
˜
η
41+ ˜
η
2(
1−
χ
p0)
×
(
1+ ˜
η
2)(
χ
p0−
2χ
p1)
−
4(
1+ ˜
η
2)
χ
p0+
2W1 1+ ˜
η
2(
1−
χ
p0)
log 2−
η
˜
41+ ˜
η
2(
1−
χ
p0)
(
1+ ˜
η
2)(
χ
p0−
2χ
p2)
+
2W1 1+ ˜
η
2(
1−
χ
p0)
log
.
(3.2)InviewofEqs.(2.12)and
(2.15)
,wecanexpressalltheauxiliaryparametersintermsofv (oritscoefficientsv0,v1,andv2):χ
p0=
1−
v20,
χ
p1=
1−
v20−
2v0v1−
(
1−
v20)
2 1+ ˜
η
2v2 0,
χ
p2= −
2v0v2,
W1= −
(
1+ ˜
η
2)(
1−
v2 0)
1+ ˜
η
2v2 0.
(3.3) Thisleadsto C3η˜≈
16c d 3η
˜
arctanh˜
η
1
−
v20 1+ ˜
η
2+
1 4(
1+ ˜
η
2)(
1−
v2 0)
1+ ˜
η
2v2 0 2×
(
1+ ˜
η
2)
⎛
⎜
⎝(
1−
v20)
1+ ˜
η
2v20⎛
⎜
⎝
21
+ ˜
η
2((
1−
v2 0)
arctanh˜
η
1
−
v20 1+ ˜
η
2− ˜
η
log 16⎞
⎟
⎠
− ˜
η
1−
v0(
3v0−
2v30−
4v1+
v0(
1−
v20−
4v0v1)
η
˜
2)
+
η
˜
(
1+ ˜
η
2)(
1−
v20−
4v0v2)
4(
1+ ˜
η
2)(
1−
v2 0)(
1+ ˜
η
2v20)
log
.
(3.4)Tofixv0,v1,andv2,onecanusethesmall
expansionoftheangulardifference
whereweidentifiedtheangulardifference
φ
1 withthemagnonmomentum p ontheworldsheet.Theresultis[7]
v0=
cotp2˜
η
2+
csc2 p 2,
(3.5) and v1=
v0(
1−
v20)
1−
log 16+ ˜
η
22−
v20(
1+
log 16)
4(
1+ ˜
η
2v2 0)
,
v2=
1 4v0(
1−
v 2 0).
(3.6) Byusing(3.5)
,(3.6)
in(3.4)
,onefinds Cη3˜≈
16c d 3η
˜
arcsinhη
˜
sinp 2+
(
1+ ˜
η
2)
sin 2 p 2 4˜
η
2+
csc2 p 2×
2˜
η
2+
csc2p 2arcsinh˜
η
sinp 2− ˜
η
(
1+
log 16)
+ ˜
η
log.
(3.7)Theexpansionparameter
intheleadingorderisgivenby
[7]
=
16 exp⎡
⎣−
J1 g+
21+ ˜
η
2˜
η
arcsinh˜
η
sinp 2!
"
"
#
1
+ ˜
η
2sin2 p2 1+ ˜
η
2sin2 p 2⎤
⎦ .
(3.8)HereweusedEq.
(2.5)
forthestringtensionT .Thefinalexpressionforthenormalizedstructurecostantisgivenby
Cη3˜
≈
16c d 3η
˜
arcsinh˜
η
sinp 2−
4η
˜
(
1+ ˜
η
2)
sin3 p 21
+ ˜
η
2sin2 p 2 1+
J1 g˜
η
2+
csc2 p 2 1+ ˜
η
2×
exp⎡
⎣−
J1 g+
21+ ˜
η
2˜
η
arcsinh˜
η
sinp 2!
"
"
#
1+ ˜
η
2sin2 p 2 1+ ˜
η
2sin2 p 2⎤
⎦
.
(3.9)Letuspointoutthatinthelimit
η
˜
→
0,(3.9)
reducestoC3
≈
16 3 c d sin p 2 1−
4 sinp 2 sinp 2+
J1 g exp−
J1 g sinp2−
2,
whichreproducestheresultfortheundeformedcasefoundin
[11]
.AnothercheckisthatthissatisfiesEq.(2.19)withcomputedin
[7]
≡
E−
J1≈
2g1
+ ˜
η
2 1˜
η
arcsinh˜
η
sinp 2−
4(
1+ ˜
η
2)
sin3 p 21
+ ˜
η
2sin2 p 2×
exp⎡
⎣−
J1 g+
21+ ˜
η
2˜
η
arcsinh˜
η
sinp 2!
"
"
#
1+ ˜
η
2sin2 p 2 1+ ˜
η
2sin2 p 2⎤
⎦
.
(3.10) 4. ConcludingremarksHereweobtainedtheexact semiclassical3-point correlationfunctionbetweentwofinite-sizegiantmagnons“heavy”stringstatesand the“light”dilatonoperatorwithzeromomentuminthe
η
-deformed AdS5×
S5.Itisgivenintermsofthecompleteellipticintegralsof thefirst and thirdkind. We proved theconsistency ofourresultby takinga derivative ofthe conformaldimension w.r.t.the coupling constant.Wealsoprovidedtheleadingfinite-sizeeffectexpansionofthestructureconstant.Itwill be interesting to compute other three-point correlation functionsof the
η
-deformed backgroundsuch as HHHto whichour resultmaybeuseful.Acknowledgements
Thiswork was partially supported by the Korean–Eastern European cooperation in research anddevelopment through the National ResearchFoundation ofKorea (NRF) (NRF-2013K1A3A1A39073412)(CA) andtheBrain PoolProgram (131S-1-3-0534)(PB) bothfunded bythe Ministry of Science,ICTandFuturePlanning. CA isalsosupported in partby theSFB647 “Raum-Zeit-Materie. Analytischeund GeometrischeStrukturen” andthe MarieCurie NetworkGATIS oftheEuropean Union’s Seventh FrameworkProgramme FP7-2007-2013 undergrantagreementNo.317089.
Appendix A. TheMathematicacodefortheconsistencycheck(Eq.(2.19)) J
[
g−] :=
2Tη
√
(
xn−
xm[
g])
xp[
g]
xp[
g]
EllipticK(
xp[
g] −
xm[
g])
xn(
xn−
xm[
g])
xp[
g]
−
xm[
g]
EllipticPi 1−
xm[
g]
xp[
g]
,
(
xp[
g] −
xm[
g])
xn(
xn−
xm[
g])
xp[
g]
;
p[
g−] :=
2xm[
g]
η
1−
xp[
g]
(
1−
xm[
g])(
xn−
xm[
g])
xp[
g]
EllipticK(
xp[
g] −
xm[
g])
xn(
xn−
xm[
g])
xp[
g]
−
EllipticPi xp[
g] −
xm[
g]
(
1−
xm[
g])
xp[
g]
,
(
xp[
g] −
xm[
g])
xn(
xn−
xm[
g])
xp[
g]
;
En[
g−] :=
2T(
xp[
g] −
xm[
g])
η
√
(
1−
xm[
g])(
xn−
xm[
g])
xp[
g]
EllipticK(
xp[
g] −
xm[
g])
xn(
xn−
xm[
g])
xp[
g]
;
T=
1
+
η
2g;
Eq1=
D[
J[
g],
g] ==
0;
Eq2=
D[
p[
g],
g] ==
0;
sol
=
Solve[{
Eq1,
Eq2}, {
D[
xm[
g],
g],
D[
xp[
g],
g]}];
xpd
=
D[
xp[
g],
g]/.
sol[[
1]];
xmd=
D[
xm[
g],
g]/.
sol[[
1]];
threept=
8c 31+
η
2FullSimplify[
D[
En[
g] −
J[
g],
g]/.{
D[
xp[
g],
g] →
xpd,
D[
xm[
g],
g] →
xmd}]
16c−
EllipticK xn(−xm[g]+xp[g]) (xn−xm[g])xp[g]+
EllipticPi 1−
xmxp[[gg]],
xn((xn−−xmxm[[gg]+])xpxp[[gg])] xm[
g]
3η
√
(
−
1+
xm[
g])(−
xn+
xm[
g])
xp[
g]
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