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Page 1: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Classical and quantum aspects ofultradiscrete solitons

Atsuo Kuniba (Univ. Tokyo)

2 April 2009, Glasgow

Page 2: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Tau function of KP hierarchy

τi(x) = 〈i|eH(x) exp( N∑

j=1

cjψ(pj)ψ∗(qj)

)|i〉

(eH(x) = time evolution op. involving β1, β2, . . .)

τi(x) = det(1 + F )

= 1 +∑

1≤j≤N

Fjj +∑

1≤j1<j2≤N

∣∣∣∣Fj1j1 Fj1j2

Fj2j1 Fj2j2

∣∣∣∣ + · · · ,

Fjl =cjqj

pj − ql

(pj

qj

)i−1 ∏m

βm − qj

βm − pj

Page 3: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Ultradiscrete (tropical) limit

limε→+0

ε log τi(x)

with an elaborate ε-tuning of the parameters

cj, pj, qj, βm

leads to a tropical tau function associated withcombinatorial data called Rigged Configuration in Bethe ansatz.

Solitons in tau function ↔ Strings in Bethe ansatz

cjψ(pj)ψ∗(qj)

Page 4: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Example from sln=4

λ

02

3

µ(1)

10

µ(2)

0

µ(3)

Rigged configuration

(µ, r) = (λ, (µ(1), r(1)), . . . , (µ(n−1), r(n−1)))

µ(a): configuration (Young diagram)

r(a): rigging (integers attached to µ(a))

(+ selection rule)

Charge of rigged configuration

c(µ, r) :=1

2

n−1∑

a,b=1

Cab min(µ(a), µ(b)) − min(λ, µ(1)) +

n−1∑a=1

|r(a)|

min(λ, µ) =∑

ij min(λi, µj), |r| =∑

i ri

(Cab) = Cartan matrix of sln)

Regard rigged conf. = {strings}, string = row attached with rigging.

Page 5: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Tropical tau function

τi(λ) = − min(ν,s)

{c(ν, s) + |ν(i)|} (1≤ i≤n)

min(ν,s)

extends over the power set of (µ, r). e.g.,

µ(1)

02

3

µ(2)

10

µ(3)

0

Proposition ([K-Sakamoto-Yamada 2007] “Tropical Hirota eq”. )

τk,i−1 + τk−1,i = max(τk,i + τk−1,i−1, τk−1,i−1 + τk,i − λk),

where

τk,i = τi(λ1, . . . , λk), τk,i = τk,i|r(a)→r(a)+δa1µ(1)

Page 6: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Rigged configuration originates in string hypothesis in Bethe ansatz

Example from sl2 (Heisenberg chain)

H =L∑

k=1

(σxkσx

k+1 + σykσy

k+1 + σzkσz

k+1)

Bethe equation for length L = 6 chain with 3 down spins.

(u1 + i

u1 − i

)6

=(u1 − u2 + 2i)(u1 − u3 + 2i)

(u1 − u2 − 2i)(u1 − u3 − 2i),

(u2 + i

u2 − i

)6

=(u2 − u1 + 2i)(u2 − u3 + 2i)

(u2 − u1 − 2i)(u2 − u3 − 2i),

(u3 + i

u3 − i

)6

=(u3 − u1 + 2i)(u3 − u2 + 2i)

(u3 − u1 − 2i)(u3 − u2 − 2i).

Page 7: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

• 0.859•• −0.859

000

•2.02i

••−2.02i

0

•−0.472 − i

•−0.472 + i

• −0.944

00

•−i

• •i

01

•0.472 − i

•0.472 + i

• 0.944

02

Page 8: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Kerov-Kirillov-Reshetikhin (1986) gave a canonical bijection

“Bethe root” “Bethe vector”

{rigged configurations} KKR←→ {highest paths}000

121212 (1 =↑, 2 =↓)

0 111222

00

121122

01

112212

02

112122

which may viewed as a combinatorial analogue of Bethe ansatz.

Page 9: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Higher rank example (sl4)

{rigged configurations} 1:1←→ {highest paths}

λ

02

3

µ(1)

10

µ(2)

0

µ(3)

←→ 111 122 22 13 23 4 3

“Bethe roots” “Bethe vectors”

highest path = b1 b2 . . . bL

bi = row shape (λi) semistandard tableau.

(+ highest condition)

Page 10: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Example of KKR algorithm from sl3

00

1

0 021

0 01

0

01

0 11

0 1 ∅

∅ ∅ ∅ ∅ ∅ ∅∅

-2 -3

-1 -2 -3

-2 -1 -1

Top left rigged configurationKKR7−→ 11232132

Page 11: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Theorem.([KSY])

Image of the KKR map

(λ, (µ(1), r(1)), . . . , (µ(n−1), r(n−1)))KKR7−→ b1 . . . bL

bk = (

xk,1︷ ︸︸ ︷1 . . . 1, . . . ,

xk,n︷ ︸︸ ︷n . . . n)︸ ︷︷ ︸

λk

(semistandard tableau),

is given by

xk,i = τk,i − τk−1,i − τk,i−1 + τk−1,i−1

We will see that this is an analogue of

u = −2∂2 log τ

∂x2

for KdV eq.

Page 12: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Crystals for Uq(sln)

Bl = { i1, . . . , il | semistandard}

equipped with crystal structures.

ul := 11. . . 1 ∈ Bl is the (classically) highest element.

An element of Bλ1 ⊗ Bλ2 ⊗ · · · is called a path.

Page 13: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Combinatorial R

R : Bl ⊗ Bm∼→ Bm ⊗ Bl, x ⊗ y 7→ y ⊗ x

xi − xi = yi − yi = Qi(x ⊗ y) − Qi−1(x ⊗ y) (i mod n),

xi = ] of letter i in tableau x (yi : similar),

Qi(x ⊗ y) = min1≤k≤n

{k−1∑

j=1

xi+j +n∑

j=k+1

yi+j} · · · i th local energy.

Example : 1233 ⊗ 124 ' 133 ⊗ 1224

will be denoted by

1233

124

133

1224 or simply 1233

124

133

1224

Page 14: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Energy Ei of path b1 ⊗ · · · ⊗ bk (i mod n)

Ei(b1 ⊗ · · · ⊗ bk) := Sum of Qi(x ⊗ y) attached to all vertices in

bkb2b1

u∞

Theorem.([KSY] “Tropical fermionic formula”)

Suppose b1 ⊗ · · · ⊗ bLKKR←→ (µ, r) −→ {τk,i}. Then,

Ei(b1 ⊗ · · · ⊗ bk) = τk,i (1 ≤ k ≤ L)

Page 15: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Uq(sln) vertex model at q = 0

Tl : B1 ⊗ B1 ⊗ B1 ⊗ · · · −→ B1 ⊗ B1 ⊗ B1 ⊗ · · ·b1 ⊗ b2 ⊗ b3 ⊗ · · · 7−→ b′

1 ⊗ b′2 ⊗ b′

3 ⊗ · · ·

· · ·Bl 3 ul

b1 b2 b3 b4

b′1 b′

2 b′3 b′

4

T1, T2, . . . : commuting family of time evolutions(deterministic transfer matrices)

Page 16: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Example of time evolution T2 :

11 11 11 11 11 11 11 11 1114 24 12 11 131 4 2 1 1 3 1 1 1 1 1 1 1

1 1 1 4 2 1 3 1 1 1 1 1 111 11 11 11 11 11 11 11 11 1114 24 12 13

1 1 1 1 1 4 2 3 1 1 1 1 111 11 11 11 11 11 11 11 11 1114 24 34 13

1 1 1 1 1 1 1 2 4 3 1 1 111 11 11 11 11 11 11 11 11 1112 14 34 13

1 1 1 1 1 1 1 1 2 1 4 3 1

The dynamics on vertical edges reproduces Box-ball systemwith carrier (Takahashi, Satsuma, Matsukidaira).

· · · 1421131111111 · · ·· · · 1114213111111 · · ·· · · 1111142311111 · · ·· · · 1111111243111 · · ·· · · 1111111121431 · · ·

1= empty box, 2, 3, 4 = colored balls.

Page 17: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Theorem.([KSY])

(1) Tropical tau function

= Energy of crystal (math) · · · previous theorem

= Baxter’s corner transfer matrix for box-ball system (phys)

Let b1 b2 · · · bLKKR←→ (µ, r) −→ {τk,i}. Then,

b1 b2 · · · bk

τk,i = ] of “balls” in

?

time evolution T∞

(2) Tropical Hirota equation = eq. of motion of box-ball system.

Page 18: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Bethe ansatz Corner transfer matrix

main combinatorial object rigged configurationenergy (charge)

in crystal

role in box-ball system action-angle variable tau function

dynamics linear bilinear

Page 19: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Dynamics of box-ball system in terms of rigged configuration

t = 0: 111122221111133211431111111111111111111111111111

t = 1: 111111112222111133214311111111111111111111111111

t = 2: 111111111111222211133243111111111111111111111111

t = 3: 111111111111111122221132433111111111111111111111

t = 4: 111111111111111111112221322433111111111111111111

t = 5: 111111111111111111111112211322433211111111111111

t = 6: 111111111111111111111111122111322143321111111111

t = 7: 111111111111111111111111111221111322114332111111

(148)

λ

4t6 + 3t

11 + 2t

µ(1) µ(2)

10

µ(3)

0

configuration · · · conserved quantity (action variable)

rigging · · · linear flow (angle variable)

KKR bijection · · · direct/inverse scattering map (separation of variables)

Page 20: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Summary so far

KP tau

Tropical tau

Charge

classical

quantum

Ultradiscretization (top down)

Comb. Bethe ansatz (bottom up)

(energy of crystal)

• KKR theory = inverse scattering scheme of box-ball systemon ∞ lattice [K-Okado-S-Takagi-Y 2006]

• Initial value problem solved and General N -soliton solutionconstructed for sln symmetric tensor reps. [KSY 2007]

(sl2 2-dim. rep. case also by [Mada-Idzumi-Tokihiro 2008])

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Periodic generalization (sl2 case)

Tl : B1 ⊗ B1 ⊗ · · · ⊗ B1 −→ B1 ⊗ B1 ⊗ · · · ⊗ B1

b1 ⊗ b2 ⊗ · · · ⊗ bL 7−→ b′1 ⊗ b′

2 ⊗ · · · ⊗ b′L

· · ·Bl 3 u

b1 b2 b3 b4

b′1 b′

2 b′3 b′

4

bL

b′L

u′ ∈ Bl

Choice s.t. u=u′: periodic box-ball system (Yura-Tokihiro 2002)

Example of T3 : ( B1 = { 1 , 2 } )

1 1 2 2 2 1 1 1 1 2 2

2 2 1 1 1 2 2 2 1 1 1

122 112 111 112 122 222 122 112 111 111 112 122

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Action-angle variables

any path highest path rigged conf.

cyclic shift KKR

b1......bL 7−→ bd+1...bLb1...bd 7−→ (µ, I) (not unique)

Iµg

Iµg−1

Iµ1

¾ µ1-

···¾ µg−1

-

¾ µg-

µ = (µ1, . . . , µg)

I = (Iµ1, . . . , Iµg)

pi := L − 2∑

j∈µ min(i, j)

Lemma. (For simplicity assume µ1 > · · · > µg)

• µ is unique and invariant under {Tl} (action variable)

• (I + d h1)/AZg is unique (angle variable), where

hl = (min(l, i))i∈µ ∈ Zg, A =(δijpi + 2 min(i, j)

)i,j∈µ

Page 23: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

P(µ) := {paths whose action variable = µ} iso-level set

J (µ) := Zg/AZg set of angle variables

Φ : P(µ) −→ J (µ) by Φ(b1 . . . bL) := (I + d h1)/AZg

Theorem. ([KT-Takenouchi 2006] “Tropical Abel-Jacobi” map)

Φ is a bijection and

P(µ)Φ−→ J (µ)

Tl

yyTl

P(µ)Φ−→ J (µ)

is commutative.

where Tl(J) = J + hl on J (µ).

Nonlinear dynamics becomes straight motion in

J (µ) = Zg/AZg,

which is an tropical analogue of Jacobi variety.

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Solution of initial value problem (inverse method)

22121111222111direct scattering Φ

- 36

2

?

linear flow T 10003

30032006

1002

mod AZ3

54

10

inverse scattering Φ−1

¾

?

12211122111122(answer)

T 10003

Page 25: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

Tropical Riemann theta (z ∈ Rg):

Θ(z) := − minn∈Zg

{tnAn/2 + tnz}

Theorem. ([K-Sakamoto 2006] “Tropical Jacobi inversion”)

J (µ) → P(µ)

(µ, I) 7→ b1 b2 . . . bL (∈ {1, 2}L)

is given by

bk = 1 + Θ(J − kh1

) − Θ(J − (k−1)h1

)

− Θ(J − kh1 + h∞

)+ Θ

(J − (k−1)h1 + h∞

),

with Ji = Ii − 12pµi

.

• Also obtained in [Mada-Idzumi-Tokihiro 2008].

• Higher spin generalization, Θ-formula for Carrier [KS2008].

Page 26: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

• Tropical period matrix A originates in Bethe ansatz at q = 0.(KKR is q = 1.)

Uq(sl2) Bethe equation at q = 0 under string hypothesis:

Ax ≡ constant vector mod AZg · · · linear!

x ∈ (R/Z)g : Bethe root

Bethe root x1:1←→ J ∈ J (µ) = Zg/AZg via Ax = J.

• Generic dynamical period is the minimum N s.t.

N ×(velocity vector) ∈ AZg → N = LCM(1,

j

det A

det A[j]

).

A is known for ∀affine g [K-Nakanishi 2002].

∃Conjectures for generic dyamical period, etc.

Page 27: Classical and quantum aspects of ultradiscrete solitonswebpark1739.sakura.ne.jp/atsuo/Glasgow2009.pdfxi =] of letter i in tableau x (yi: similar); Qi(x › y) = min 1•k•n f kX¡1

A(1)2 path = 121121213322111133211 ∈ B⊗21

1

l LCM of = period under Tl

1 1, 21, 21, 21, 21 212 1, 822

29, 822

95, 411

46, 411

37822

3 1, 95922

, 959176

, 959169

, 959127

9594 1, 2877

50, 2877

400, 2877

820, 2877

4632877

A(1)3 path = 134·34·1·134·23·1·13 ∈ B3⊗B2⊗B1⊗B3⊗B2⊗B1⊗B2

(r, l) LCM of = period under T(r)l

(1,1) 1, 38039

, 956, 95

6, 380

31, 380

27, 380

29380

(1,2) 1, 19039

, 9512

, 9512

, 19031

, 19027

, 19029

190(2,1) 1, 190

13, 95

4, 95

4, 190

137, 190

9, 190

73190

(2,2) 1, 765, 38

3, 38

3, 76

41, 76

21, 76

3176

(2,3) 1, 956, 95

11, 95

11, 95

34, 95

48, 95

4195

(3,1) 1, 38013

, 952, 95

2, 380

137, 380

9, 380

263380

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“I haven’t a slightest idea of what people did with it.”

· · · H. Bethe