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Boundary States and Black p-branes. Shinpei Kobayashi ( RESCEU ) in collaboration with Tsuguhiko Asakawa (RIKEN) So Matsuura (RIKEN). 2004/05/19, 関東ゼミ. 1. Introduction.
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Boundary States and Black p-branes Shinpei Kobayashi (RESCEU) in collaboration with Tsuguhiko Asakawa (RIKEN) So Matsuura (RIKEN) 2004/05/19, 関東ゼミ
1. Introduction How should we apply string theory to gravitational systems ?What is ‘string cosmology’ ? → D-brane is thought to be a key to describe well-known gravitational systems via string theory.
X0 σ=0 σ=π τ Xi X D-brane • Open string endpoints can stick to D-brane • D-branes carry RR charges
Dynamical non-BPS D-brane systems are very important in string theory, (e.g.) • D(2p+1)-brane in type IIA string • D(2p)-brane in type IIB string • D/anti D-brane system(c.f.) BPS D-branes, stable non-BPS D-brane But no one has succeeded in describing the dynamics of non-BPS D-brane.
Non-BPS D-brane system (1)D(2p+1)-brane Closed string vacuum
Non-BPS D-brane system (2)D/anti D-brane system closed string vacuum lower-dimensional D-brane
Importance of dynamical D-brane systems • String theory • Searching for ‘real’ vacuum of string theory • String interaction & dynamics →non-perturbative string theory • Gravitation & Cosmology • D-brane inflation • Black hole evaporation → Application to physics at Planck scale
Trials to dynamical D-brane systems • Via ‘non-perturbative’ string theory • Open string field theory (A.Sen, …) • Closed string field theory (Asakawa, SK &Matsuura (’03), …) • Via conformal field theory • Logarithmic CFT description (Asakawa, Ishimoto, SK & Matsuura, work in progress)
Trials to dynamical D-brane systems • Via low-energy effective theory(Zhou & Zhu (‘99), Ohta & Yokono (‘02) Brax, Mandal & Oz (‘01)) • Time-dependent solutions have not found yet. • Stable BPS solution →OK black p-branes : Today’s theme • Non-BPS solution → ?
SUGRA String theory Dynamical system Hawking radiation, Inflation, etc. unknown object ? Unknown non-BPS black p-brane non-BPS D-brane (BPS) black p-brane BPS D-brane
D-brane/black p-brane relation • Stable BPS D-brane case • (Unstable non-BPS case) • Black p-brane from boundary state (= D-brane) • (Difference between D-brane and black p-brane)
2. Black p-brane • Classical solution of SUGRA • It has same symmetry, charge and mass as a D-brane → Low-energy description of a D-brane.But no one has proved. • (Non-BPS black p-branes have not been found yet)
String Theory and SUGRA String Field Theory action Supergravity action massless EOM EOM Classical solution of Sting theory Dp-brane Classical solution of SUGRA Black p-brane massless
SUGRA action & ansatz ・Φ:dilaton ・ A:n-form potential ・ F:(n+1)-form field strength
X0 σ=0 σ=π τ Xi X
3. Boundary state • D-brane in closed string channel • Source of closed strings← Such properties are guaranteed by conformal symmetry of the world-sheet conformal transformationζ→ f(ζ), where ζ=σ+iτ
Using the conformal transformation, we can change the boundary condition for open strings into that for closed strings.
Closed string Open string D-brane Boundary state Open string 1-loop graph Closed string tree graph
We can rewrite the boundary condition with using the oscillators.
<B| |massless>
(e.g.) dilaton (10-dim.) <B| |φ> +…
We can extract each mode which are included in Φ, for example, dilaton, graviton, antisym.tensor and so on. • Such modes corresponds to the leading term of the classical solution.
<B| |> +… <B| |> + <B| Calculation of fields
Here, we do not know how strings interact, so we use 3-point coupling of SUGRA. SFT SUGRA
(e.g.) dilaton (10-dim.) <B| |φ> +… <B| |φ> + <B|
ΦΦh A AΦ + A k1 k1 Φ Φ hμν k3 k3 Φ k2 k2 A
Φ hμν k k
(c.f.) SUGRA Φ hμν Bμν ・・・ + +…
5. Summary • Black p-branes are the classical solutions of SUGRA and they are thought to correspond to D-branes in low energy limit. • Boundary states are another representation of D-branes, which are written in closed string channel. • Using 3-point coupling of SUGRA, we can reproduce the asymptotic behavior of a black p-brane from a boundary state .
6. Problem • STF coupling ⇔ SUGRA coupling ? • Degrees of freedom of field-redefinitiongraviton of SFT ⇔ graviton of SUGRA ? • Difference between D-brane and black p-brane→ massive mode effect→ Hawking radiation, etc.
7. Future Works • We are now investigating... • Classical solution for unstable non-BPS D-brane • D-brane deformation using String Field Theory or CFT • Application • Hawking radiation in terms of D-brane • D/anti-D brane inflation