arXiv subjects

Youngjai Kiem

Publications and source records attributed to Youngjai Kiem.

At least 19 recordsLinked to original sources

arXiv2003

Chiral primary cubic interactions from pp-wave supergravity

We explicitly construct cubic interaction light-cone Hamiltonian for the chiral primary system involving the metric fields and the self-dual four-form fields in the IIB pp-wave supergravity. The background fields representing pp-waves exhibit SO(4)*SO(4)*Z_2 invariance. It turns out that the interaction Hamiltonian is precisely the same as that for the dilaton-axion system, except for the fact that the chiral primary system fields have the opposite parity to that of the dilaton-axion fields under the Z_2 transformation that exchanges two SO(4)'s.

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arXiv2002

PP-wave/Yang-Mills Correspondence: An Explicit Check

We present an explicit evidence that shows the correspondence between the type IIB supergravity in the pp-wave background and its dual supersymmetric Yang-Mills theory at the interaction level. We first construct the cubic term of the light-cone interaction Hamiltonian for the dilaton-axion sector of the supergravity. Our result agrees with the corresponding part of the light-cone string field theory (SFT) and furthermore fixes its previously undetermined $p^+$-dependent normalization. Adopting thus fixed light-cone SFT, we compute the matrix elements of light-cone Hamiltonian involving three chiral primary states and find an agreement with a prediction from the dual Yang-Mills theory.

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arXiv2002

One-loop Noncommutative U(1) Gauge Theory from Bosonic Worldline Approach

We develop a method to compute the one-loop effective action of noncommutative U(1) gauge theory based on the bosonic worldline formalism, and derive compact expressions for N-point 1PI amplitudes. The method, resembling perturbative string computations, shows that open Wilson lines emerge as a gauge invariant completion of certain terms in the effective action. The terms involving open Wilson lines are of the form reminiscent of closed string exchanges between the states living on the two boundaries of a cylinder. They are also consistent with recent matrix theory analysis and the results from noncommutative scalar field theories with cubic interactions.

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arXiv2001

Anatomy of One-Loop Effective Action in Noncommutative Scalar Field Theories

One-loop effective action of noncommutative scalar field theory with cubic self-interaction is studied. Utilizing worldline formulation, both planar and nonplanar part of the effective action are computed explicitly. We find complete agreement of the result with Seiberg-Witten limit of string worldsheet computation and standard Feynman diagrammatics. We prove that, at low-energy and large noncommutativity limit, nonplanar part of the effective action is simplified enormously and is resummable into a quadratic action of scalar open Wilson line operators.

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arXiv2001

Noncommutative Q-balls

We obtain Q-ball solutions in noncommutative scalar field theory with a global U(1) invariance. The Q-ball solutions are shown to be classically and quantum mechanically stable. We also find that "excited Q-ball" states exist for some class of scalar potentials, which are classically stable in the large noncommutativity limit.

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arXiv2001

Path integral formulation of Hodge duality on the brane

In the warped compactification with a single Randall-Sundrum brane, a puzzling claim has been made that scalar fields can be bound to the brane but their Hodge dual higher-rank anti-symmetric tensors cannot. By explicitly requiring the Hodge duality, a prescription to resolve this puzzle was recently proposed by Duff and Liu. In this note, we implement the Hodge duality via path integral formulation in the presence of the background gravity fields of warped compactifications. It is shown that the prescription of Duff and Liu can be naturally understood within this framework.

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arXiv2000

Factorization and generalized *-products

The generalized *-products, or the $*_N$-products, appear both in the one-loop effective action of noncommutative Yang-Mills theories and in the coupling of a closed string to N open strings on a disk when the D-brane world-volume is noncommutative. Factorization of the string amplitudes provides a uniform understanding of the $*_N$-products and a hint to obtain a simple, explicit formula (in the momentum space) for arbitrary N in the non-Abelian case. Possible extension to a more general ${}_M *_{N}$-product in the M-loop context is discussed.

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arXiv2000

Open string derivation of winding states in thermal noncommutative field theories

The `winding state' behavior appears in the two-loop nonplanar contribution to the partition function in thermal noncommutative field theories. We derive this feature directly from the purely open string theory analysis in the presence of the constant background $B$-field; we compute the two-loop partition function for worldsheets with a handle and a boundary when the time direction of the Euclideanized target space is compactified. In contrast to the closed-string-inspired approach, it is not necessary to add infinite number of extra degrees of freedom. Furthermore, we find a piece of supporting evidence toward the conjecture that, in the UV limit, the noncommutativity parameter plays the role of the effective string scale in noncommutative field theories.

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arXiv2000

Noncommutative Field Theory from String Theory: Two-loop Analysis

Noncommutative ϕ^3 field theory in six dimensions exhibits the logarithmic UV/IR mixing at the two-loop order. We show that open string theory in the presence of constant background NS-NS two-form field yields the same amplitude upon taking a decoupling limit. The stretched string picture proposed on the basis of one-loop analysis naturally generalizes to the two-loop amplitudes in consideration. Our string theory formulation can incorporate the closed string insertions as well as open string insertions. Furthermore, the analysis of the world-sheet partition function and propagators can be straightforwardly generalized to Riemann surfaces with genus zero but with an arbitrary number of boundaries.

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arXiv2000

Stretched strings and worldsheets with a handle

In the presence of the constant background NS two-form gauge field, we construct the worldsheet partition functions, bulk propagators and boundary propagators for the worldsheets with a handle and a boundary. We analyze the noncommutative $ϕ^3$ field theory amplitudes that correspond to the general two-point insertions on the two-loop nonplanar vacuum bubble. By the direct string theory amplitude computations on the worldsheets with a handle, which reduce to the aforementioned field theory amplitudes in the decoupling limit, we find that the stretched string interpretation remains valid for the types of amplitudes in consideration. This completes the demonstration that the stretched string picture holds up in the general multiloop context.

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arXiv2000

UV/IR Mixing in Noncommutative Field Theory via Open String Loops

We explicitly evaluate one-loop (annulus) planar and nonplanar open string amplitudes in the presence of the background NS-NS two-form field. In the decoupling limit of Seiberg and Witten, we find that the nonplanar string amplitudes reproduce the UV/IR mixing of noncommutative field theories. In particular, the investigation of the UV regime of the open string amplitudes shows that certain IR closed string degrees of freedom survive the decoupling limit as previously predicted from the noncommutative field theory analysis. These degrees of freedom are responsible for the quadratic, linear and logarithmic IR singularities when the D-branes embedded in space-time have the codimension zero, one and two, respectively. The analysis is given for both bosonic and supersymmetric open strings.

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arXiv1999

Closed Strings Interacting with Noncommutative D-branes

Closed string dynamics in the presence of noncommutative Dp-branes is investigated. In particular, we compute bulk closed string two-point scattering amplitudes; the bulk space-time geometries encoded in the amplitudes are shown to be consistent with the recently proposed background space-time geometries dual to noncommutative Yang-Mills theories. Three-point closed string absorption/emission amplitudes are obtained to show some features of noncommutative Dp-branes, such as modified pole structures and exponential phase factors linearly proportional to the external closed string momentum.

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arXiv1999

Non-perturbative membrane spin-orbit couplings in M/IIA theory

Membrane source-probe dynamics is investigated in the framework of the finite N-sector DLCQ M theory compactified on a transverse two-torus for an arbitrary size of the longitudinal dimension. The non-perturbative two fermion terms in the effective action of the matrix theory, the (2+1)-dimensional supersymmetric Yang-Mills theory, that are related to the four derivative F^4 terms by the supersymmetry transformation are obtained, including the one-loop term and full instanton corrections. On the supergravity side, we compute the classical probe action up to two fermion terms based on the classical supermembrane formulation in an arbitrary curved background geometry produced by source membranes satisfying the BPS condition; two fermion terms correspond to the spin-orbit couplings for membranes. We find precise agreement between two approaches when the background space-time is chosen to be that of the DLCQ M theory, which is asymptotically locally Anti-de Sitter.

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arXiv1999

Supersymmetric completion of supersymmetric quantum mechanics

Via supersymmetry argument, we determine the effective action of the SU(2) supersymmetric Yang-Mills quantum mechanics up to two constants, which results from the full supersymmetric completion of the F^4 term. The effective action, consisting of zero, two, four, six and eight fermion terms, agrees with the known perturbative one-loop calculations from the type II string theory and the matrix theory. Our derivation thus demonstrates its non-renormalization properties, namely, the one-loop exactness of the aforementioned action and the absence of the non-perturbative corrections. We briefly discuss generalizations to other branes and the comparison to the DLCQ supergravity analysis. In particular, our results show that the stringent constraints from the supersymmetry are responsible for the agreement between the matrix theory and supergravity with sixteen supercharges.

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arXiv1999

Eleven-dimensional massless superparticles and matrix theory spin-orbit couplings revisited

The classical probe dynamics of the eleven-dimensional massless superparticles in the background geometry produced by N source M-momenta is investigated in the framework of N-sector DLCQ supergravity. We expand the probe action up to the two fermion terms and find that the fermionic contributions are the spin-orbit couplings, which precisely agree with the matrix theory calculations. We comment on the lack of non-perturbative corrections in the one-loop matrix quantum mechanics effective action and its compatibility with the supergravity analysis.

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arXiv1999

BTZ black holes from the five-dimensional general relativity with a negative cosmological constant

We show that the five-dimensional general relativity with a negative cosmological constant allows the solutions of the form M_3 \times M_g where M_3 is the three-dimensional BTZ black hole and M_g is a higher genus (g>1) Riemann surface with a fixed size. It is shown that this type of spontaneous compactification on a Riemann surface is possible only for the genus larger than one. From type IIB string theory point of view, certain near horizon geometry of D three-branes wrapped on the compact Riemann surface (g>1) is the BTZ (or AdS_3) space-time tensored with the Riemann surface and a constant size five-sphere. The relevance of our analysis to the positive energy conjecture of Horowitz and Myers is discussed.

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arXiv1998

A Non-perturbative Evidence toward the Positive Energy Conjecture for asymptotically locally AdS_5 IIB Supergravity on S^5

We consider the classical solution of the type IIB supergravity spontaneously compactified on S^5, whose metric depends only on the radial coordinate and whose asymptotic geometry is locally that of AdS_5, i.e., R \times S^1 \times T^2. We solve the equations of motion to obtain the general solutions satisfying these conditions, and find that the only naked-singularity-free solutions are the AdS black holes and AdS solitons. The other solutions, that smoothly interpolate these two solutions, are shown to have naked singularities even though their Ricci tensor is proportional to the metric with a negative constant. Thus, among the possible solutions of this type, the AdS solitons are the unique lowest energy solution; this result is consistent with the recently proposed positive energy conjecture for the IIB AdS supergravity on S^5.

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arXiv1998

Exactly solvable charged dilaton gravity theories in two dimensions

We find exactly solvable dilaton gravity theories containing a U(1) gauge field in two dimensional space-time. The classical general solutions for the gravity sector (the metric plus the dilaton field) of the theories coupled to a massless complex scalar field are obtained in terms of the stress-energy tensor and the U(1) current of the scalar field. We discuss issues that arise when we attempt to use these models for the study of the gravitational back-reaction.

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