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Remarks on Topologial Models and

Frational Statistis

C.A.S. Almeida

UniversidadeFederaldoCeara-Departamentode Fsia

C.P.6030,60470-455, Fortaleza,CE,Brazil

Reeivedon22February,2001

OneofthemostintriguingaspetsofChern-Simons-typetopologialmodelsisthefrational

statis-tisofpointpartileswhihhasbeenshownessentialforourunderstandingofthefrational

quan-tumHalleets. Furthermorethese ideasare appliedtothe studyofhighT superondutivity.

WepresenthereanreentlyproposedmodelforfrationalspinwiththePauliterm. Ontheother

hand,inD=4spae-time,aShwarz-typetopologialgaugetheorywithantisymmetritensorgauge

eld, namelyB^F model, isreviewed. Antisymmetritensoreldsare onjetured asmediator

ofstringinteration. Adimensionalredutionofthepreviousmodelprovidesa(2+1)dimensional

topologialtheory,whihinvolvesa2-formBanda0-form. Somereentresultsonthismodelare

reported. Reently,therehavebeenthoughtsofgeneralizingunusualstatististoextendedobjets

inothersspae-timedimensions,andinpartiulartotheaseofstringsinfourdimensions. Inthis

ontext,disussionsaboutfrationalspinandantisymmetritensoreldarepresented.

I B ^F Models

Shwarz-type theories are purely topologial in the

sense that theirpartition funtionsare independentof

themetriandthattheonlyobservablesinthese

theo-riesare topologialinvariantsof theunderlying

spae-time manifoldM. Other observablesdesribe linking

andintersetionnumberofmanifoldsofanydimension.

Commonly alled BF systems, they are

harater-ized by a BRST-gauge xed quantum ation whih

dier from the lassial ation only by a

BRST-ommutator whih ontains the whole metri

depen-deneofthequantumation. Ontheotherhand,sine

the vaumexpetation value ofa BRST-ommutator

vanishes,theseeldtheoriesmaybeobtainedfromthe

lassialations[1℄. Furthemore,ifwedenoteasQthe

BRST-operatorwhihisnilpotent,inthesetheoriesthe

energy-momentum tensorisQtrivial,i.e.,

T

=fQ;

g (1)

where

representseldsandthemetri.

Conneted to BF systems, it is worth mentioning

that antisymmetri tensor elds theories have been

studied during the past years. They play an

impor-tantrole in the realization of thevarious strong-weak

oupling dualitiesamong stringtheories. An

antisym-metritensorofrankp 1ouplesnaturallytoan

ele-mentaryextendedobjetofdimensionp 2,namelya

(p 2)brane.

As an example of an abelian BF system onsider

the following metri independent ation on an

D-dimensionalmanifoldM.

S(D;p)= Z

M B

p ^dA

D p 1

; (2)

whereAandB areforms,pdenotingtheirrank,^

de-notingtheirwedgeprodutanddistheexterior

deriva-tive.

InpartiulartheabelianB^F four-dimensional

a-tionis

S

BF =

Z

M

4

fB^Fg: (3)

B =B

dx

^dx

;F =dA;A=A

dx

: (4)

This ationis formulatedin termsof thetwo-form

potential B while F = dA is the eld-strength of a

one-formgaugepotentialA.

(2)

Appliations:

Field theories desribing the low-energy limit of

fundamental string theories typially ontain

higher-ranktensorelds.

ThetopologialontributionomingfromBF

the-ories appear even in those physial theories with non

trivial physial Hamiltonian where the BF term

ap-pearsasaninterationterm.

Coloronnementmodels.

Axioniosmistrings.

QCDstrings.

Topologiallymassivemodels.

II Gauge invariant massive B^ F

model in D = 4.

Our starting point is an abelian gauge theory whih

ontainsthevetoreldAandtheantisymmetrield

B,andinorporatedthetopologialtermB^F inthe

four-dimensionalation[2℄

S

BF =

Z

M

4

1

2 H^

H 1

2 F^

F+kB^F

: (5)

Here H = dB is the eld-strength of a two-form

gaugepotentialB,kisamassparameter,andisthe

Hodge star(duality)operator. Theationaboveis

in-variantunderthefollowingtransformations:

ÆA=d;ÆB=d; (6)

where and are zero and one-form transformation

parametersrespetively,andgivestheequationsof

mo-tion

d

H =F (7)

and

d

F=H: (8)

Applyingd

onbothsidesof eq. (8)andusingthe

eq. (7),weget

(d

d

+ 2

)F =0: (9)

Repeatingtheproedureaboveinreverseorder,we

ob-taintheequationofmotionforH

(d

d

+ 2

)H =0: (10)

Theseequationsanberewrittenas

(+ 2

)F =0 (11)

and

(+ 2

)H=0: (12)

III Abelian gauge invariant

massive models in D = 3

Dimensional redution !B^' models.

Dimensional redution is usually done by

expand-ing the elds in normal modes orresponding to the

ompatiedextradimensions,andintegratingoutthe

extradimensions. Thisapproahis veryusefulindual

models and superstrings. Here,however,weonly

on-sidertheeldsinhigherdimensionstobeindependent

oftheextradimensions.

Inthisase,weassumethat oureldsare

indepen-dentoftheextraoordinatex

3

:From(3),on

perform-ingdimensionalredutionasdesribedabove,wegetin

threedimensions

S = Z

M

3

fB^d+V ^Fg; (13)

whereV andarea1-formanda0-formelds

respe-tively.

WereognizethatB^distopologialinthesense

that thereis noexpliitdependene onthespae-time

metri. Onehastostressthatthistermmaynotbe

on-fused with the two-dimensional versionof the B^F,

whih involves a salar and a one-form elds.

More-over,atermthat isequivalentto thefour-dimensional

B^Ftermispresentination(13)(theso-alledmixed

Chern-Simonsterm,V ^F).

Non-Chern-Simonsgaugeinvariantmassive

modelsin D=3:

Now, in order to show thetopologial mass

gener-ation for the vetorand tensor elds, we onsider the

modelwiththetopologialtermB^d,andwith

prop-agationforthetwo-formgaugepotentialBandforthe

zero-formeld, representedbytheation

S= Z

M3

1

2 H^

H+ 1

2 d^

d+B^d

; (14)

where the seond term is a Klein-Gordon term, is

a mass parameter and H = dB is a three-form

eld-strengthofB.

The ation above is invariant under the following

(3)

where and are zero and one-form transformation

parametersrespetively.

We follow herethe samesteps that has beenused

by Allen et al. [2℄ in order to show the

topologi-al mass generation in the ontext of B ^F model.

Thus, we nd the equations of motion for salar and

tensor elds, whih are respetively d

H = d and

d

d = H: Consequently, we obtain the equations

(d d + 2

)d=0and(d

d

+ 2

)H=0:

Theseequationsanberewrittenas

(+ 2

)

=0 (16)

and

(+ 2

)H =0: (17)

Therefore,theutuationsofandH aremassive.

Obviously,thesetwopossibilitiesannotours

simul-taneously. Indeed, in the most interesting ase, the

degreeoffreedom ofthemasslesseld is"eatenup"

bythegaugeeldB tobeomemassiveandtheeld

ompletelydeouples fromthetheory[3℄.

IV N = 1 D = 4 massive B ^ F

! N = 2 D = 3 massive B^'

models

N=1 D=4massiveB^F model.

Let us begin by introduing the N = 1 D = 4

supersymmetri BFextendedmodel. For extendedwe

meanthatweinludemasstermsfortheKalb-Ramond

eld. Thismasstermwill beintrodued herefor later

omparison to the tridimensional ase. Atually, this

onstrution an be seen as a superspaeand abelian

versionof the soalled BF-Yang-Mills models. These

modelsaredesribedbytheation

S

BF YM =

Z

M4 Tr

kB^F + g 2 4 B^ B : (18)

Note that, on-shell, (18)is equivalent to thestandard

YM ation. This formalismwasused by Fuito et al.

[4℄in ordertostudyquarkonnement.

Asourbasisupereldationwetake[5℄

S SS BF = 1 8 Z d 4 xf i[ Z d 2 B W Z d 2 B _ W _ ℄ + g 2 2 [ Z d 2 B B + Z d 2 B _ B _

℄g: (19)

where W

is aspinor supereld-strenght,B

is a

hi-ral spinor supereld,

D B =0, and g are massive

parameters. Theirorresponding-expansionsare:

W

(x;;

) = 4i

(x) [4Æ

D(x)+2i( ) F (x)℄ +4 2 _ _ (20) B

(x;;)=e i [i (x)+ T (x)+ (x)℄, (21) where T =T () +T [℄ = 4i( ) B +2"

(M+iN):

(22)

Our onventions for supersymmetri ovariant

derivativesare D +i _ _ D _ _ i _ . (23)

We all attention for the eletromagneti

eld-strenghtand the antisymmetri gaugeeld whih are

ontainedin W

andB

,respetively. Intermsofthe

omponentselds,theation(19)anbereadas

S= Z d 4 xf[ i 2 + 2 B e F DN℄ + 2 _ _ + _ ( ) _ +g 2 [ 1 8 + + 1 2 B B 1 2 M 2 +N 2 ℄g = Z d 4 x[( i 2 5 + 2 + 2 B e F DN) +g 2 ( 1 8 + 1 2 B B 1 2 M 2 +N 2

)℄:(24)

Inthelastequalityabove,thefermionieldshavebeen

organizedasfour-omponent Majoranaspinors as

fol-lows = _ ; = _ ; = _ ; (25)

and we denote the dual eld-strenght dening e F 1 2 " F

. Furthermore,weusethefollowing

identi-ties = + 5 = = + . (26)

Wehavenotonsideredouplingwithmattereldsand

apropagationterm forthegaugeelds. Onthe other

hand,oursupespaeBFtermwasonstrutedinavery

simple way. A quite similar onstrution was

(4)

Theo-diagonal massterm(or

5

) hasbeen

shown by Brooks and Gates, Jr. [7℄ in the ontext of

super-Yang-Mills theory. Notethat theidentity

5 = i 2 " (27)

revealsaonnetionbetweenthetopologialbehaviour

denoted by the Levi-Civita tensor "

; and the

pseudo-esalar

5 :

So, it is worthwhile to mentionthat this term has

topologial origin and it an be seen as a fermioni

ounterpart of the BF term. In our opinion, this

fermionimasstermdeservesmoreattention.

The N=2 D=3massiveB^'model

Wewill now arry outa dimensional redution in

thebosonisetorof(24). Hene,afterdimensional

re-dution, the bosoni setorof (24) an be written as

[5℄ S bos: = Z d 3 xf[" V F +" B

' DN℄

+g 2 [ 1 2 B B V V 1 2 M 2 +N 2

℄g;(28)

where V

is a vetorial eld and ' represents a real

salareld. Notiethat thersttermin r.h.s. of (28)

an be transformed in the Chern-Simons term if we

identify V

A

. The seond one is the so alled

B^'term.

Nowletusproeedto thedimensional redutionof

thefermionisetorofthemodel. First,note thatthe

Lorentz group in three dimensions is SL(2;R ) rather

than SL(2;C) in D = 4. Therefore, Weyl spinors

withfourdegreesoffreedomwillbemappedintoDira

spinors. Sotheorretassoiationskeepingthedegrees

offreedomareskethedas

= _ ! = i = _ ! = i = _ ! = i : (29)

From(29),wendthat

! 1 2 ( + + + ) ! 1 2 ( + b b + b b + ) 5 ! 1 ( + +

+ ): (30)

where hatted index means three-dimensional

spae-time.

Thus,thedimensionallyreduedfermionisetorof

(24)maybewritten

S ferm: = Z d 3 xf i 4 ( + + + )+ 4 ( + b b + b b + )+ g 2 16 ( + + +

)g.(31)

TheationS=S

bos: +S

ferm:

isinvariantunderthe

following supersymmetry transformations (from now

on,greekindiesmeanthree-dimensionalspae-time):

Æ = iD ( ) F Æ = iD ( ) F ÆF = i ( ) i ( ) ÆD = ( + ) (32) Æ( i

) = Æ

=i e T e T ; Æ e T = + ; Æ( i

) = Æ

= i ( ) T ( ) T , (33)

where and are supersymmetri parameters, whih

indiates that we have two supersymmetries in the

aforementionedation.

V Frational statistis - anyons

Thefrationalstatistis[8℄withitstheoretialand

ap-pliableonsequenesplaysaninterestinginterplayrole

between quantum eld theory and ondensed matter

physis. Previous speulations [9℄ that the frational

quantum Hall eet ould be explained by

quasipar-tiles (anyons) obeying frational statistis were

on-rmedandthebehaviouroftwo-dimensionalmaterials

suh asvortiesin superuid heliumlms may be

ex-plained by frational statistis. As it is known, the

presene ofChern-Simons termsin (2+1) dimensional

gaugetheoriesinduefrationalstatistis. Insuh

the-ories, it has been known that there exist exitations,

alled anyons, whih ontinously interpolate between

bosons and fermions. In the well-known physial

re-alization, anyons are omposite quasi-partiles where

magnetiux-tubesareattahedtohargedpartiles.

Reently, there have been thoughts of

(5)

stringsin four dimensions[10℄. AbelianBF models in

four dimensionshas also been exploited in dual

mod-els of osmi strings, and axioni blak hole theories

wheretheaxionhargeisphysiallydetetableonlyby

externalosmistringsinafourdimensional

Aharanov-Bohmtypeproess[11℄.

Anezirisetal. [12℄showedthatmoregeneral

statis-tis an exist in (3+1) dimensions. Statistial phases

of BF theoryan beseen toarise from ertainosmi

string and superstring phenomena, as well as in the

Nambu-Gotostringtheorymodiedwiththeinlusion

of theKalb-Ramondeld(Beld) [13℄.

VI Linking number -

interse-tion number

Inareentinterestingwork,AshtekarandCorihi[14℄

showed that there is a preise in whih the

Heisen-berg unertainty between uxes of eletri and

mag-netieldsthroughnitesurfaesisgivenbytheGauss

linking numberoftheloopsthat bound thesesurfaes.

Topologialeldtheoriespresentsobservablesother

thanthepartitionfuntion. Wittenhasarguedthatin

thesetheoriesWilsonloopsareappropriatemetri

inde-pendentandgaugeinvariantobjets. Polyakovhas

re-latedthevauumexpetationvaluesofWilsonloopsin

theabelianChern-SimonstheorytothelassialGauss

linking numberoftwoloops.

IntheaseofBFsystems,weanreinterpretingthe

linking numberastheintersetion numberofoneloop

withadisboundedbytheotherloop. So,this

observ-able hasanatural generalizationto other dimensions.

Considering theation (2), the elds B

p and A

D p 1

allowus toform thefollowingmetriindependentand

gaugeinvariantexpressions("Wilsonsurfaes"):

W[L℄=exp Z

L A

;W[℄=exp Z

B

(34)

where and L are disjointompat and orientedp

and (D p 1)-dimensional boundaries of two

ori-entedsubmanifold of anD-dimensional oriented

man-ifold M: This formalism was presented by Blau and

Thompson[15℄,whoprovedthattheexpetationvalue

W(;L)=hW

B ()W

A

(L)iisequaltothelinking

num-berofthe"surfaes".

VII Frational statistis in D=3

from B ^' term?

S =S

0 +

Z

d 3

x

2 "

B

'+

g

2 J

B

+hj'

;

(35)

where g;h are oupling onstants, J

and j are

ur-rentsandsoures. S

0

dependsonlyoneldsthat

orig-inate urrents and soures. Integrating out the elds

B

and',wearriveat

S

eff =S

0 hg

4 Z Z

d 3

xd 3

yJ

(x)h B

(x)'(y)ij(y):

(36)

From(35) andusing theLandau gauge, is easy to

seethat

hB

(x)'(x)i="

x

G(x y); (37)

where

G(x y)= 1

4 1

jx yj

; (38)

Therefore

hB

(x)'(x)i= "

4

(x y)

jx yj 3

; (39)

The orrelation funtion hB

(x)'(y)i is

tanta-mounttotheorrelationfuntion hA

(x)A

(y)iofthe

pureChern-SimonstheoryintheLandaugauge

(trans-verse propagator). The eetive ation (36) an be

rewrittenas

S

eff =S

0 hg

4 1

4 "

Z Z

d 3

xd 3

yJ

(x) (x y)

jx yj 3

j(y)

(40)

and

S

eff =S

0 hg

4

(linking number ) (41)

On the other hand, Blau and Thompson [15℄

sug-gest appliation of their formalism to the ase where

B isazero-formandAisaone-form,involvinga

link-ing number of a point P and a irle , through the

expression

W

B (P)W

A

(d)=exp(B(P)+ I

A) (42)

whereadisdisboundedby.

These results support our speulation that wean

(6)

VIII Pauli's term and frational

statistis in D=3.

As it is known, the presene of Chern-Simons terms

in (2+1) dimensional gauge theories indue frational

statistis[16, 17℄. Stern [18℄ was the rst, as far as

weknow,tosuggestanonminimaltermintheontext

oftheMaxwell-Chern-Simonseletrodynamiswiththe

intention of mimiking ananyonibehaviorwithout a

pureChern-Simonslimit. Thistermanbeinterpreted

asatreelevelPauli-typeoupling,i. e.,ananomalous

magnetimoment. It isaspei featureof (2+1)

di-mensions that the Pauli oupling exists, not only for

spinningpartiles,butalsoforsalarones[19℄.

We onsider here an Abelian Chern-Simons-Higgs

theorywheretheomplexsalareldsouplesdiretly

to the eletromagneti eld strength (Pauli-type

ou-pling). The Lagrangianof the model under

investiga-tionis

L=jr

j

2

+

2 "

A

A

A

b+

2 b

2

(43)

where r

(

ieA

i

g

4 "

F

). Note that

this ovariantderivativeinludesboththeusual

mini-malouplingandtheontributionduetoPauli'sterm.

Here A

is the gauge eld and the Levi-Civita

sym-bol"

isxedby"

012

=1andg

=diag(1; 1; 1).

Themultipliereldbhasbeenintroduedtoimplement

theovariantgauge-xingondition.

Beforequantizingthetheory,weanalyzetheabove

LagrangianintermsofHamiltonianmethods. Herewe

followtheapproahusedbyShinetal. [20℄. Wearry

out the onstraint analysis of this model, in order to

obtainaonsistentformulationofthetheory.

The anonial momenta of the Lagrangian (43),

whih an be easily seen by onsidering its temporal

andspatialomponentsseparately,aregivenby

0

=0; (44)

b = A

0

; (45)

j

=

2 "

ij

A

i i

g

2 "

ij

[

(D

i

) (D

i )

g 2

2

j

A

0 jj

2

+ g

2

4 (

0 A

0 )jj

2

; (46)

=(

0

)+ieA

0

+i g

4

" ij

F

ij

; (47)

=(

0

) ieA

0

i

g

" ij

F

ij

; (48)

where

0 ,

j

;

b

; and

aretheanonialmomenta

onjugatetoA

0 ; A

j

,b;and

respetively. Alsowe

haveused"

ij ="

0ij ,D

i =

i ieA

i

andi;j=1;2.

The anonial momenta (44) and (45) do not

in-volveexpliittime dependene and heneareprimary

onstraints. Performing the Legendre transformation,

theanonialHamiltoniananbewritten as

H

=

+jDj 2

+ieA

0

(

)+" ij

A

0

i A

j

+A

i

i

b

2 b

2

i g

2 "

ij

j A

0 [

(D

i

) (D

i )

g 2

4

i A

0

i

A

0 jj

2 g

4 "

ij

F

ij [

(D

0

) (D

0 )

g 2

8 F

ij

F

ij jj

2

:(49)

Now,inordertoimplementtheprimaryonstraints

inthetheory,weonstruttheprimaryHamiltonianas

H

p =H

+

0 +

1 (

b +A

0

); (50)

where

0 and

1

are Lagrange multiplier elds.

Con-serving in timetheprimary onstraintsyieldsthe

se-ondaryonstraints

1 =

0

0; (51)

2 =

b +A

0

0; (52)

whih are also onserved in time and where the

sym-bolindiatesweakequality,i. e.,theonstraintsan

be identially set equal to zero only after omputing

the relevant Poisson brakets. Thus there is no more

onstraintandtheaboveequationsaretheset offully

seond-lass onstraints. On the other hand, there is

norst-lassonditionsandso,nogaugeonditionsto

bedetermined intheory. Thisisaneetofthegauge

xing ondition imposed previously. As it is known,

thelakofphysialsignianeallowsthatthe

seond-lass onstraintsanbeeliminated by meansof Dira

brakets(DB's).

Following the standard Dira brakets formalism

andquantizingthesystem,weobtainthefollowingset

ofnon-vanishingequal-timeommutators:

[A

0

(x);b(y)℄=iÆ 2

(x y) (53)

[A

i (x);

j

(y)℄=iÆ

ij Æ

2

(x y) (54)

[(x);(y)℄=[

(x);

(y)℄=iÆ 2

(7)

Afterahievingthequantizationweproeedto

on-strut the angular momentum operator and ompute

theangularmomentum ofthemattereld .

Thesymmetrienergy-momentumtensoranbe

ob-tainedbyouplingtheeldstogravityandthenvarying

theationwithrespettog

:

T

=

2

p

g ÆS

Æg

=(r

)

(r

)+(r

)

(r

)

A

b A

b

g

(jr

j

2

A

b):(56)

The angularmomentum operator in (2+1)

dimen-sionsisgivenby

L= Z

d 2

x" ij

x

i T

0j :

Hene

L= Z

d 2

x" ij

x

i f(

j +

j

) ieA

j J

0

i g

2 "

jl F

l0

(

) A

0

j b

+A

j

0 b i

g

2 A

j "

k l

k [

(D

l

) (D

l )

+i g

2

2 A

j

k (jj

2

F 0k

)g; (57)

where

J

0

=if

g

2e "

ij

i [

(D

j

) (D

j )

+i g

2

2e

i (jj

2

F 0i

)g (58)

isthetemporalomponentoftheonservedmatter

ur-rent.

The key point here is that Gauss' law is no more

a onstraint, while J

0 and T

ontain derivatives of

A

. Note that, due to its topologial harater, the

Chern-Simonstermdoesnotontributetothe

energy-momentumtensor. Theseaspetsareattributedtothe

non-linearityintroduedbyPauli'sterm.

Therotationalpropertyoftheeldisobtainedby

omputing theommutator [L;(y)℄. Using equations

(53-55)and(57),itiseasytoseethat

[L;(y)℄=" ij

y

i

j [e

Z

d 2

x" ij

x

i A

j J

0 ;℄

+i g

2 "

ij

"

jk y

i F

k 0

: (59)

Thisommutatoran berewrittenbymeansofthe

Q= Z

d 2

xJ

0 (x)

andbeomes

[L;(y)℄=" ij

y

i

j

e 2

4 [Q

2

;(y)℄+i g

2 "

ij

"

jk y

i F

k 0

(60)

or,inmorefamiliarnotation

[L;(y)℄=i(yr)(y) e

2

2

Q(y)+i g

2

yE(y):

(61)

The rst term in the right hand side of eq. (61)

representsthe intrinsi spinand the seond is the

so-alled rotationalanomaly, whih is responsible forthe

frationalspin. UnliketheChern-Simonsterm(whose

ontribution is related with magneti eld), the Pauli

terminduesananomalousontributionforthespinof

the system, whih depends on eletri eld [21℄. We

stressthat,herethenonminimalouplingonstantisa

freeparameter.

Itisworthmentioningthatalltheproedureabove

anbearriedoutevenifthereisnoChern-Simonsterm

intheLagrangian(43). Inthisasetheanomalous

on-tributiontospinwouldjust omefromthePauliterm.

Now we will disuss the above result in

onne-tionwiththeoriesinthebroken-symmetryphase.

Boy-anovsky[22℄hasfoundthatthelow-lyingexitationsof

aU(1)Chern-Simonstheoryininterationwitha

om-plexsalareldinabrokensymmetrystatearemassive

bosonswithanonialstatistis. Heexplainedhisresult

asduetothesreeningoflong-rangeforesinabroken

symmetryphase. Inthis phaseloalizedharge

distri-butionsannot besupported, whih is supposed tobe

essentialforfrational spin. Onthe other hand,if we

onsideranon-minimallyoupledAbelian-Higgsmodel,

thelong-distanedampingeetbythe"photon"mass

no longer exists. This is an indiation that Pauli's

term,whihinduesananomalousspin,anberelevant

forthestudyofbrokensymmetrystates(superuid)in

theontextofeetivetheoriesinondensedmatter.

Innonrelativistilimit,CarringtonandKunstatter

[23℄haveshownthat anomalous magnetimoment

in-terations gives riseto both the Aharonov-Bohm and

Aharonov-Casher eets. They have speulated

pos-sible anomalous statistiswithout the CS term. As a

matteroffat,webelievethatthis(inarelativisti

the-ory)wasprovedhere. Ontheotherhand,theAbelian

Chern-Simons term an be generated by means of a

spontaneoussymmetry breakingof anonminimal

(8)

Pauli-termat tree-level(withthe nonminimaloupling

on-stantgasafreeparameter)anonstituteaneetive

theorywhihbringusinformationaboutphysial

mod-elsinbrokensymmetryphase.

Aknowledgments

I would like to thank my ollaborators R. R.

Landim, D. M. Medeiros, F. A. S. Nobre and M. A.

M.Gomeswhihontributedformanyresultsreported

here. This work was supported in part by Conselho

NaionaldeDesenvolvimentoCientoeTenol

ogio-CNPqand Funda~aoCearensedeAmparoa

Pesquisa-FUNCAP.

Referenes

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[16℄ G.Semeno,Phys.Rev.Lett.61,517(1988).

[17℄ G. Dunne, Self-Dual Chern-Simons Theories,

hep-th/9410065.

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[20℄ H. Shin, W-T.Kim and J-K. Kim, Phys. Rev.D46,

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