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This research has been co-financed by the European Union (European - - PowerPoint PPT Presentation

This research has been co-financed by the European Union (European Social Fund, ESF) and Greek national funds through the Operational Program Education and Lifelong Learning of the National Strategic Reference Framework (NSRF), under the


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This research has been co-financed by the European Union (European Social Fund, ESF) and Greek national funds through the Operational Program ”Education and Lifelong Learning” of the National Strategic Reference Framework (NSRF), under the grants schemes ”Funding of proposals that have received a positive evaluation in the 3rd and 4th Call

  • f ERC Grant Schemes” and the program ”Thales”

1

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Gauge/Gravity Duality 2013 Munich, 29 July 2013

Holography and the Chern-Simons diffusion rate

Elias Kiritsis

University of Crete APC, Paris

2-

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SLIDE 3

Bibliography

Based on recent work with: Umut Gursoy, (Utrecht), Ioannis Iatrakis (Crete), Francesco Nitti, (APC), Andy O’Bannon (Cambridge) arXiv:1212.3894 [hep-ph] and based also on past work with:

  • Umut Gursoy, (Utrecht), Liuba Mazzanti (Utrecht), Francesco Nitti,

(APC) arXiv:0903.2859 [hep-th] arXiv:0707.1349 [hep-th]

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 3

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SLIDE 4

Introduction: Instantons

  • Instantons are important topological semiclassical configurations of SU(Nc)

YM theory.

  • They are responsible for the existence of an infinite number of degenerate

vacua, and a new coupling constant (the instanton angle θ that breaks the CP symmetry in YM).

4

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SLIDE 5
  • When they can be treated as a dilute instanton gas, their contributions

are exponentially small in perturbation theory,

∼ e−8π2 Nc

λ

  • However, instantons have a size, and large instantons are affected by the

IR coupling of the YM Theory that is strong.

  • This is the reason that, although we know how to calculate with individual

instantons, the dynamical contributions of instantons to many YM processes are un-calculable.

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 4-

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SLIDE 6

Instantons at large Nc

  • Because the instanton factor e−8π2 Nc

λ

is exponentially suppressed with Nc, instanton effects should be exponentially small in the large-Nc limit.

  • Veneziano-Witten, solving the η′-puzzle, pointed out that this is some-

times false.

  • In QCD, at T=0, the instanton charge is effectively continuous, the in-

stantons cannot be treated like a gas (because large instantons dominate), and instan- ton effects are NOT exponentially suppressed, but only power suppressed, like other dynamical effects.

Witten ’79, Veneziano, ’79

  • In particular the mass of the η′ (the 9-th would-be Goldstone boson of

U(1)A in QCD) is Mη′ ∼ Nf Nc ΛQCD

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 5

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SLIDE 7

The U(1)A anomaly

  • The most important role of instantons is to violate the U(1)A charge

conservation in QCD Jµ

5

=

Nf

i=1

ψi γµ γ5 ψi ∂µJµ

5 = − Nf

16π2 ϵµνρσ TrFµνFρσ = − Nf 8π2 TrF ∧ F .

  • A related number is the Chern-Simons number NCS that characterizes

distinct vacua of SU(Nc) YM which cannot be connected with small gauge

  • transformations. It is defined at fixed time, spatial (3d) slices as

NCS ≡ 1 8π2

∂M d3x ϵijk Tr

[

Ai∂jAk − 2ig 3 AiAjAk

]

where i, j, k = 1, 2, 3.

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 6

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The CS diffusion rate

  • The Chern-Simon diffusion rate, ΓCS, is the rate of change of ∆NCS per unit 4-volume

and is given by the two-point function of q(xµ), ΓCS ≡ ⟨(∆NCS)2⟩ V t =

d4x ⟨q(xµ)q(0)⟩symmetric

  • In equilibrium states with finite temperature, ΓCS is given in terms of GR(ω,⃗

k)= Fourier transform of the retarded Green function of q(xµ) by: ΓCS = − lim

ω→0

2T ω Im GR(ω,⃗ k = 0) ,

  • Single instanton background contributions to ΓCS are exponentially suppressed.
  • ΓCS can be generated by thermal fluctuations in finite temperature states. Those excite

sphaleron configurations which produce non-zero ΓCS upon decay.

  • Since q(x) is a total derivative, ΓCS is identically zero in perturbation theory.
  • A finite value for ΓCS in QCD, signals the creation of net chirality bubbles because of the

anomaly of the axial current. These are domains of more left-handed than right-handed quarks or the opposite.

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 7

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The chiral magnetic effect

  • The electric current generates a magnetic field, B ∼ γZe b

R3

∼ 1018 (1019) at RHIC (LHC). Or eB ∼ 5 − 15 m2

π.

  • In neutron stars B ∼ 1010 − 1013
  • Gauss. In magnetars, B ∼ 1015

Gauss

8

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SLIDE 10
  • A magnetic field, separates spatially the electric charge of left-moving

fermions (blue is spin, brown is momentum).

  • Fluctuations of axial charge due to sphalerons, and the strong magnetic

field, will generate, charge asymmetry on an event-by-event basis.

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 8-

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What is known about ΓCS?

  • ΓCS is a crucial ingredient for the Chiral magnetic effect. The bigger it is, the bigger

are the fluctuations of the chiral asymmetry.

  • ΓCS is a non-perturbative, (Minkowskian) transport coefficient.
  • At high enough temperature, using classical field dynamics, hard thermal loop resum-

mation and (and B¨

  • deker’s effective theory). It is reliable for (αs ≪ 1,

1 log 1

αs ≪ 1)

ΓCS = 0.21 Ncg2T m2

D

(

log mD γ + 3.041

) N2

c − 1

N2

c

(Nc αs)5 T 4 m2

D = 2Nc + Nf

6 g2T 2 , γ = Ncg2T 4π

(

log mD γ + 3.041

)

, as = g2 4π

Giudice+Shaposhnikov, ’93, Moore, ’97, ’00, Moore+Tassler, ’10

  • N = 4 sYM calculation

Son+Starinets, ’02

ΓCS = λ2 28π3 T 4

  • What is ΓCS in YM?

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 9

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IHQCD

  • IHQCD is a specially chosen 5d Einstein dilaton model (with two phe-

nomenological parameters in V (λ)) S = M3

p N2 c

d5x√−g

[

R − 4 3 (∂λ)2 λ2 + V (λ)

]

where λ = eϕ and (Mpℓ)3 = 45π2.

Gursoy+Kiritsis+Nitti, ’07

V (λ) = 12 ℓ2

 1 +

n=1

Vnλn

 

, λ → 0 V (λ) ∼ λ

4 3

log λ + · · · , λ → ∞

  • The model reproduces correctly the spectra of 0++ and 2++ glueballs,

as well as the finite temperature thermodynamics.

  • It has confinement, a mass gap and asymptotically linear trajectories:

m2

n ∼ n.

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 10

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The instanton density in IHQCD

  • The instanton density q(x) is dual to an axion field, a(x, r). In N=4 sYM

this is the usual IIB axion in ten dimensions.

  • The most general action for the axion compatible with the symmetries
  • f the instanton density is

Sa = M3

p

2

d5x√g Z(λ) (∂a)2 + O

(

(∂a)4 N2

c

)

  • There is no axion potential and therefore the symmetry a → a + constant

is exact.

  • Sa is of order O(N−2

c

) compared with the IHQCD action. UV λ → 0 Z(λ) = Z0

 1 +

n=1

cnλn

 

IR λ → ∞ Z(λ) ∼ c4λ4 + · · · , lim

n→∞

m2

n(0−+)

m2

n(0++) = 1

Gursoy+Kiritsis+Mazzanti+Nitti, ’09 Holography and the Chern-Simons diffusion rate, Elias Kiritsis 11

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The θ flow

  • The axion background solution a(r) can be interpreted as a ”running”

θ-angle

  • This is in accordance with the absence of UV divergences (all correlators

⟨Tr[F ∧ F]n⟩ are UV finite), and Seiberg-Witten type solutions.

  • The equation of motion is

¨ a +

(

3 ˙ A + ˙ Z(λ) Z(λ)

)

˙ a = 0 , ds2 = e2A(r)(dr2 + dxµdxµ)

  • The metric A(r) and λ(r) are taken from the leading order solution.
  • The full solution is

a(r) = θUV + 2πk + C

∫ r

0 dre−3A

Z(λ) , C = ⟨q(x)⟩ = 1 16π2⟨Tr[F ∧ F]⟩

  • a(r) is a running effective θ-angle. Its running is non-perturbative,

a(r) ∼ r4 ∼ e− 4

b0λ 12

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  • The vacuum energy is

E(θUV ) = −M3

p

2

d5x√g Z(λ) (∂a)2 = −M3

p

2 Ca(r)

  • r=∞

r=0

  • Consistency with the θ → −θ symmetry of YM requires to impose that

a(∞) = 0. This determines the solution

Witten, ’79

C = ⟨q(x)⟩ = −θUV + 2πk

∫ ∞

0 dre−3A Z(λ)

E(θUV ) = EIHQCD + M3

p

2 Mink (θUV + 2πk)2

∫ ∞

dr e3AZ(λ)

  • The topological susceptibility χ is given by

E(θ) = N2

c E0 + 1

2χ θ2 + O

(

θ4 N2

c

)

, χ = M3

p

∫ ∞

dr e3AZ(λ)

  • The simplest parametrization of Z(λ) consistent with asymptotics is

Z(λ) = Z0

(

1 + c4λ4)

  • Z0 can be determined from the topological susceptibility (lattice, χ ≃ (191MeV)4), and c4 from the lowest

0−+ glueball mass (lattice, m0−+

m0++ = 1.50). The predicted next mass agrees well with lattice (m0⋆ −+ m0++ = 2.11).

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 12-

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The 2-point function of q(x)

  • We now proceed to calculate the 2-point function ⟨q(x)q(0)⟩ at finite

temperature, T ≥ Tc.

  • The linear fluctuation equation of the axion (in Fourier space) is consid-

ered in the black hole background, ds2 = e2A

(

dr2 f − fdt2 + dxidxi

)

,

[

1 Z(λ)√−g ∂r

(

Z(λ)√−g grr∂r

)

− gµνkµkν

]

δα(r, kµ) = 0 , with in-going wave boundary conditions at the horizon.

  • The on shell action of the fluctuation is

Son-shell

α

=

d4k (2π)4 a(−kµ) F(r, kµ) a(kµ)

  • rh

, F(r, kµ) ≡ −M3

p δα(r, −kµ) Z(λ) √−g grr ∂rδα(r, kµ)/2

  • The AdS/CFT dictionary yields that the retarded Green’s function is

ˆ GR(ω,⃗ k) = −2 lim

r→0 F(r, kµ).

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 13

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The calculation of the CS diffusion rate

  • We can calculate directly the IR limit of GR and therefore ΓCS to be

ΓCS sT/N2

c

= Z(λh) 2π , which has implicit dependence on T through Z(λh). λh is the value of the dilaton at the black hole horizon.

  • On the large black hole branch, ΓCS/(sT/N2

c ) is bounded from below by

its value in the T → ∞ limit, lim

T→∞

ΓCS sT/N2

c

= Z0 2π .

1 2 3 4 5 6 TTc 0.99990 0.99995 1.00000 1.00005 1.00010 1.00015 1.00020 CSΚ2 Z02 Π s TNc2

14

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  • The previous calculation of ΓCS is not reliable because:

(a) The parametrization was crude (b) λh < 1

  • The largest polynomial correction to Z(λ) for small values of λ will come

from linear terms so we reparametrize Z(λ) as Z(λ) = Z0

(

1 + c1λ + c4λ4)

  • To constrain c1 we will demand that our holographic results for the axial

glueball masses fall within one σ of the lattice values for the two first 0−+ glueball masses 0 < c1 < 5 , 0.06 < c4 < 50

  • Simple non-monotonic Z(λ)s with the desired asymptotics, produce glue-

ball masses that deviate from lattice results more than 10%.

  • This implies that the bound

ΓCS sT/N2

c

Z0 2π is always valid.

14-

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IHQCD masses of the 0−+ glueball states with excitation number n, normalized to the 0++ mass for various (c1, c4). From the top (red) dots to the bottom (blue) dots: (c1, c4) = (0, 0.26), (0.5, 0.87), (1, 2.2), (5, 24), (10, 75) The two horizontal blue lines with surrounding blue bands indicate the results and errors, respectively, of the large-N YM lattice masses of the lowest and first excited states, n = 1 and n = 2, (Morningstar-Peardon). 14-

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1 2 3 4 5 6 TTc 2 4 6 8

CSΚ2 Z02 Π s TNc2

,

1 2 3 4 5 6 TTc 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20

CSΚ2 Z02 Π s TNc2

(a) The numerical result for ΓCS/(sT/N2

c ), normalized to the T → ∞ value κ2Z0/2π, as functions of T/Tc,

for different values of the parameters (c1, c4). From the bottom (red) curve to the top (blue) curve, (c1, c4) = (0, 0.26), (0.5, 0.87), (1, 2.2), (5, 24), (10, 75), (20, 230), (40, 600). (b) Close-up of the curves for (from bottom to top) (c1, c4) = (0, 0.26), (0.5, 0.87), (1, 2.2). 14-

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  • A numerical estimate of ΓCS near the confinement-deconfinement phase

transition is ΓCS(Tc) T 4

c

= 0.31 × Z(λc) 2π > 0.31 × Z0 2π = 1.64 , where we have used the lattice result for the entropy density, s(Tc) = 0.31N2

c T 3 c , (Lucini-Teper-Wenger).

  • At 1 σ an upper bound can also be set to ΓCS(Tc). In total

1.64 ≤ ΓCS(Tc) T 4

c

≤ 2.8

  • We may compare this range of values with the N=4 result taking the

standard values, λ ≃ 6π to get a result that is at least 40 times smaller. N = 4 sYM : ΓCS(T) T 4 ≃ 0.045

  • A naive extrapolation of the Moore-Tassler high temperature formula to

αs = 0.5, gives the right order of magnitude, ΓMT

CS (Tc)

T 4

c

= 30α5

s

≃ 1 (1)

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 14-

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The CS correlator

5 10

k Tc

20 40

Ω Tc

0.002 0.001 0.000 0.001

Im GR Tc Mp

3

Our numerical results for ∆Im GR(ω,⃗ k = 0; Tc, 2Tc)/(TcM3

p ) as a function of

ω/Tc and |⃗ k|/Tc. As |⃗ k| increases up to |⃗ k|/Tc ≈ 10, the largest peak shifts from ω/Tc ≈ 22 up to ω/Tc ≈ 30. The width of the peak changes very little.

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 15

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Outlook

  • The Chern-Simons diffusion rate seems to be non-negligible in QCD and

is bounded below.

  • CP-odd phenomena above Tc seem to be controlled by a long lived exci-

tation that has the same order of magnitude mass as the 0−+ glueball.

  • Fixing better Z(λ) by the fitting to a lattice calculation of the Euclidean

2-point function of q(xµ) is an important future plan.

  • Calculate ΓCS in a model which incorporates the flavor degrees of freedom

as well (V-QCD).

  • The currents which appear in chiral magnetic effect can be calculated

holographically upon addition of the flavor in the pure glue background. In this case, a vacuum state with a magnetic field and net chirality should be constructed.

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 16

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SLIDE 24

.

Thank you

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 17

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This research has been co-financed by the European Union (European Social Fund, ESF) and Greek national funds through the Operational Program ”Education and Lifelong Learning” of the National Strategic Reference Framework (NSRF), under the grants schemes ”Funding of proposals that have received a positive evaluation in the 3rd and 4th Call

  • f ERC Grant Schemes” and the program ”Thales”

18

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Changes of NCS

  • The change of NCS during a dynamical process is given by

∆NCS =

d4x q(xµ) q(xµ) ≡ 1 16π2

M Tr [F ∧ F] =

1 32π2 ϵµνρσTrFµνFρσ .

  • We conclude that instantons mediate the changes of axial U(1) charge.

∆N5 = (NL − NR)|t=∞ − (NL − NR)|t=−∞ = 2Nf ∆NCS .

19

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SLIDE 27
  • In a thermal plasma, such fluctuations of axial U(1) number are controlled

by a Langevin-like process d(∆N5) dt = −ξCS ∆N5 + η(t) , ⟨η(t)η(t′)⟩ ≃ ΓCSδ(t − t′) where ΓCS is the Chern-Simons diffusion rate.

  • As usual, the white-noise correlation is controlled by the symmetric cor-

relator while the friction coefficient ξCS is controlled by the retarded corre- lator.

  • Consider now the transition amplitude, A, from a state |ψ1(t1)⟩ to |ψ2(t2)⟩

times the change in axial number A ∆N5 = 2

d4x⟨ψ2|q(x)|ψ1⟩ Taking the square of the above equation, summing over all possible |ψ2(t2)⟩ and using the completeness relation I = ∑ |ψ2⟩⟨ψ2| we obtain ⟨(∆N5)2⟩ = 4

d4x d4y ⟨ψ1| q(x) q(y) |ψ1⟩ RETURN

19-

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SLIDE 28
  • The Chern-Simon diffusion rate, ΓCS, is the rate of change of ∆NCS per unit 4-volume

and is given by the two-point function of q(xµ), ΓCS ≡ ⟨(∆NCS)2⟩ V t =

d4x ⟨q(xµ)q(0)⟩symmetric

  • In equilibrium states with finite temperature, ΓCS is given by

ΓCS = 2T ξCS = − lim

ω→0

2T ω Im GR(ω,⃗ k = 0) , where GR(ω,⃗ k)= Fourier transform of the retarded Green function of q(xµ).

  • Single instanton background contributions to ΓCS are exponentially suppressed.
  • ΓCS can be generated by thermal fluctuations in finite temperature states. Those excite

sphaleron configurations which produce non-zero ΓCS upon decay.

  • Since q(x) is a total derivative, ΓCS is identically zero in perturbation theory.
  • Finite ΓCS in QCD, signals the creation of net chirality bubbles (domains of more left-

handed than right-handed quarks or the opposite) because of the anomaly of the axial current.

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 19-

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The θ RG flow

100 200 300 400 500 600 E MeV 0.0 0.2 0.4 0.6 0.8 1.0 Θ ΘUV

  • The effective θ vanishes in the IR. q(r) is a marginally-irrelevant operator.
  • We have taken: Z(λ) = Z0(1 + c4λ4) ≃ 133

4 (1 + 0.26λ4)

  • The effective θ-angle “runs” also in the D4 model for QCD, and also

vanishes in the IR θ(U) = θ(1 − U3

0/U3)

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 20

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The CS spectral function

  • We now calculate the axion spectral function ImGR(ω,⃗

k) for non-zero ω and |⃗ k|. We first set ⃗ k = 0

  • For small ω, the axion fluctuation equation yields Im GR(ω,⃗

k = 0) ∝ ω.

  • For large ω, we expect Im GR(ω,⃗

k = 0) ∝ ω4 because the theory is conformally invariant in the UV and q(xµ) has dimension four.

21

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15 20 25 30 35 40

Ω Tc

0.1 0.2 0.3 0.4 0.5

Im GR Tc Mp

3

Im GR(ω,⃗ k = 0)/(TcM3

p ) as a function of ω/Tc, at Tc. The red dots are our

numerical results that match the solid blue curve, (1.6×10−7)×(ω/Tc)4.051, which is the expected large ω behavior of the spectral function.

21-

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SLIDE 32
  • The ω4 scaling of Im GR(ω,⃗

k = 0) at large ω comes from the UV (free) part of the two-point function.

  • It overwhelms peaks in Im GR(ω,⃗

k), rendering them practically invisible.

  • To eliminate the large-ω divergence we compute GR(ω,⃗

k) at two different temperatures, T1 and T2, and then take the difference, ∆GR(ω,⃗ k; T1, T2) ≡ GR(ω,⃗ k)

  • T2 − GR(ω,⃗

k)

  • T1 .

21-

slide-33
SLIDE 33

10 20 30 40 50 60

Ω Tc

0.0010 0.0005 0.0005

Im GR Tc Mp

3

The difference ∆Im GR(ω,⃗ k = 0; Tc, 2Tc)/(TcM3

p ) as a function of ω/Tc.

The difference goes to zero as ω/Tc → ∞. The prominent minimum at ω/Tc ≈ 10 and maximum at ω/Tc ≈ 22 indicate a shift in spectral weight with increasing T, possibly from the motion of a peak in the spectral function. There is a peak at ω ≃ 20Tc ≃ 1600MeV and width ∼ 10Tc ∼ 1300MeV. Holography and the Chern-Simons diffusion rate, Elias Kiritsis 21-

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SLIDE 34

Comparison with lattice data (Meyer)

n 3000 4000 5000 6000 M n 3000 4000 5000 6000 M

(a) (b) Comparison of glueball spectra from our model with b0 = 4.2, l0 = 0.05 (boxes), with the lattice QCD data from Ref. I (crosses) and the AdS/QCD computation (diamonds), for (a) 0++ glueballs; (b) 2++ glueballs. The masses are in MeV, and the scale is normalized to match the lowest 0++ state from Ref. I.

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 22

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SLIDE 35

The fit to glueball lattice data

JPC Ref I (MeV) Our model (MeV) Mismatch Nc → ∞

Mismatch

0++ 1475 (4%) 1475 1475 2++ 2150 (5%) 2055 4% 2153 (10%) 5% 0−+ 2250 (4%) 2243 0++∗ 2755 (4%) 2753 2814 (12%) 2% 2++∗ 2880 (5%) 2991 4% 0−+∗ 3370 (4%) 3288 2% 0++∗∗ 3370 (4%) 3561 5% 0++∗∗∗ 3990 (5%) 4253 6% Comparison between the glueball spectra in Ref. I and in our model. The states we use as input in our fit are marked in red. The parenthesis in the lattice data indicate the percent accuracy.

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 23

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SLIDE 36

Fit and comparison

HQCD lattice Nc = 3 lattice Nc → ∞ Parameter [p/(N2

c T 4)]T=2Tc

1.2 1.2

  • V 1 = 14

Lh/(N2

c T 4 c )

0.31 0.28 (Karsch) 0.31 (Teper+Lucini) V 3 = 170 [p/(N2

c T 4)]T→+∞

π2/45 π2/45 π2/45 Mpℓ = [45π2]−1/3 m0++/√σ 3.37 3.56 (Chen ) 3.37 (Teper+Lucini) ℓs/ℓ = 0.15 m0−+/m0++ 1.49 1.49 (Chen )

  • ca = 0.26

χ (191MeV )4 (191MeV )4 (DelDebbio)

  • Z0 = 133

Tc/m0++ 0.167

  • 0.177(7)

m0∗++/m0++ 1.61 1.56(11) 1.90(17) m2++/m0++ 1.36 1.40(4) 1.46(11) m0∗−+/m0++ 2.10 2.12(10)

  • 24
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SLIDE 37
  • G. Boyd, J. Engels, F. Karsch, E. Laermann, C. Legeland, M. Lut-

gemeier and B. Petersson, “Thermodynamics of SU(3) Lattice Gauge Theory,” Nucl. Phys. B 469, 419 (1996) [arXiv:hep-lat/9602007].

  • B. Lucini, M. Teper and U. Wenger, “Properties of the deconfining

phase transition in SU(N) gauge theories,” JHEP 0502, 033 (2005) [arXiv:hep-lat/0502003]; “SU(N) gauge theories in four dimensions: Exploring the approach to N =∞,” JHEP 0106, 050 (2001) [arXiv:hep-lat/0103027].

  • Y. Chen et al., “Glueball spectrum and matrix elements on anisotropic

lattices,” Phys. Rev. D 73 (2006) 014516 [arXiv:hep-lat/0510074].

  • L. Del Debbio, L. Giusti and C. Pica, “Topological susceptibility in the

SU(3) gauge theory,” Phys. Rev. Lett. 94, 032003 (2005) [arXiv:hep- th/0407052].

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 24-

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The pressure from the lattice at different N

Marco Panero arXiv: 0907.3719 Holography and the Chern-Simons diffusion rate, Elias Kiritsis 25

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The entropy from the lattice at different N

Marco Panero arXiv: 0907.3719 Holography and the Chern-Simons diffusion rate, Elias Kiritsis 26

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SLIDE 40

The trace from the lattice at different N

Marco Panero arXiv: 0907.3719 Holography and the Chern-Simons diffusion rate, Elias Kiritsis 27

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SLIDE 41

The specific heat

1 2 3 4 5 T Tc 16 17 18 19 20 21 Cv T3 Nc

2

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 28

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SLIDE 42

The speed of sound

  • 1.0

1.5 2.0 2.5 3.0 3.5 4.0 T Tc 0.05 0.10 0.15 0.20 0.25 0.30 0.35 cs

2

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 29

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SLIDE 43

Comparing to Gubser+Nelore’s formula

  • Gubser+Nelore proposed the following approximate formula for the speed
  • f sound

c2

s ≃ 1

3 − 1 2 V ′2 V 2

  • ϕ=ϕh

1 2 3 4 5 6 0.15 0.2 0.25 0.3 0.35

Gursoy (unpublished) 2009

  • Red curve=numerical calculation, Blue curve=Gubser’s adiabatic/approximate

formula.

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 30

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SLIDE 44

Detailed plan of the presentation

  • Title page 0 minutes
  • Bibliography 1 minutes
  • Introduction: Instantons 3 minutes
  • Instantons at large Nc 4 minutes
  • The U(1)A anomaly 5 minutes
  • The CS diffusion rate 6 minutes
  • The chiral magnetic effect 9 minutes
  • What is known about ΓCS? 11 minutes
  • IHQCD 12 minutes
  • The instanton density in IHQCD 14 minutes
  • The θ-flow 18 minutes
  • The two-point function of q(x) 19 minutes
  • Calculation of the CS diffusion rate 26 minutes
  • The CS correlator 27 minutes

31

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SLIDE 45
  • Outlook 30 minutes
  • The changes of NCS 35 minutes
  • The θ RG flow 36 minutes
  • The CS spectral function 38 minutes
  • Comparison with lattice data (Meyer) 40 minutes
  • The fit to glueball lattice data 42 minutes
  • Fit and comparison 44 minutes
  • The pressure 45 minutes
  • The entropy 46 minutes
  • The trace 49 minutes
  • The free energy 51 minutes
  • The specific heat 56 minutes
  • The speed of sound 59 minutes
  • The Gubser-Nelore formula for cs 65 minutes

Holography and the Chern-Simons diffusion rate, Elias Kiritsis 31-