arXiv subjects

Soo-Jong Rey

Publications and source records attributed to Soo-Jong Rey.

At least 127 records · Page 7Linked to original sources

arXiv1997

Gravitating M(atrix) Q-Balls

Q-ball configuration that represents oscillating or spinning closed membrane is constructed via M(atrix) theory. Upon gravitational collapse Q-balls are expected to form Schwarzschild black holes. For quasi-static spherical membrane, we probe spacetime geometry induced by monopole moment via D0-parton scattering off the Q-ball. We find a complete agreement with long distance potential calculated using eleven-dimensional supergravity. Generalizing to heterotic M(atrix) theory, we also construct Q-ball configurations of real projective and disk membranes. The latter Q-ball configuration arises as twisted sector of heterotic M(atrix) theory, hence, are expected to form a charged black hole after gravitational collapse.

hep-th↗

arXiv1997

M(atrix) Theory on T9/Z2 Orbifold and Twisted Zero Brane

M(atrix) theory compactified on an orbifold ${\bf T}_9/{\bf Z}_2$ is studied. Via zero-brane parton scattering we find that each of the $2^9 = 512$ orbifold fixed points carry $-1/32$ units of zero-brane charge. The anomalous flux is cancelled by introducing a twisted sector consisting of 32 zero-branes that are spacetime supersymmetry singlets. These twisted sector zero-branes are nothing but gravitational waves propagating along the M-theory direction. There is no D0-partons in the untwisted sector, a fact consistent with holographic principle. For low-energy excitations, the orbifold compactification is described by ten-dimensional supersymmetric Yang-Mills theory with gauge group $SO(32)$.

hep-th↗

arXiv1997

Non-Orientable M(atrix) Theory

M(atrix) theory description is investigated for M-theory compactified on non-orientable manifolds. Relevant M(atrix) theory is obtained by Fourier transformation in a way consistent with T-duality. For nine-dimensional compactification on Klein bottle and Möbius strip, we show that M(atrix) theory is (2+1)-dimensional ${\cal N} = 8$ supersymmetric U(N) gauge theory defined on dual Klein bottle and dual Moebius strip parameter space respectively. The latter requires a twisted sector consisting of sixteen chiral fermions localized parallel to the boundary of dual Moebius strip and defines Narain moduli space of Chaudhuri-Hockney-Lykken heterotic string. For six-dimensional CHL compactification on S1/Z2*T4 we show that low-energy dynamics of M(atrix) theory is described by (5+1)-dimensional ${\cal N} = 8$ supersymmetric U(N)$\times$U(N) gauge theory defined on dual orbifold parameter space of S1*K3/Z2. Spacetime spectrum is deduced from BPS gauge field configurations consistent with respective involutions and is shown to agree with results from M-theory analysis.

hep-th↗

arXiv1997

Wilson Lines and T-Duality in Heterotic M(atrix) Theory

We study the M(atrix) theory which describes the $E_8 \times E_8$ heterotic string compactified on $S^1$, or equivalently M-theory compactified on an orbifold $(S^1/\integer_2) \times S^1$, in the presence of a Wilson line. We formulate the corresponding M(atrix) gauge theory, which lives on a dual orbifold $S^1 \times (S^1 / \integer_2)$. Thirty-two real chiral fermions must be introduced to cancel gauge anomalies. In the absence of an $E_8 \times E_8$ Wilson line, these fermions are symmetrically localized on the orbifold boundaries. Turning on the Wilson line moves these fermions into the interior of the orbifold. The M(atrix) theory action is uniquely determined by gauge and supersymmetry anomaly cancellation in 2+1 dimensions. The action consistently incorporates the massive IIA supergravity background into M(atrix) theory by explicitly breaking (2+1)-dimensional Poincare invariance. The BPS excitations of M(atrix) theory are identified and compared to the heterotic string. We find that heterotic T-duality is realized as electric-magnetic S-duality in M(atrix) theory.

hep-th↗

arXiv1997

Chiral Perturbation Theory for Tensor Mesons

Interactions of $a_2, K^*_2, f_2$ and $f_2'$ tensor-mesons with low-energy $π, K, η, η'$ pseudo-scalar mesons are constrained by chiral symmetry. We derive a chiral Lagrangian of tensor mesons in which the tensor mesons are treated as heavy non-relativistic matter fields. Using $1/N_c$ counting, we derive relations among unknown couplings of the chiral Lagrangian. Chiral perturbation theory is applied to the tensor-meson mass matrix. At one-loop there are large corrections to the individual tensor meson masses, but the singlet-octet mixing angle remains almost unchanged. We argue that all heavy mesons of spin $\ge 1$ share common feature of chiral dynamics.

hep-ph↗

arXiv1997

M(atrix) Theory on an Orbifold and Twisted Membrane

M(atrix) theory on an orbifold and classical two-branes therein are studied with particular emphasis to heterotic M(atrix) theory on $S_1/Z_2$ relevant to strongly coupled heterotic and dual Type IA string theories. By analyzing orbifold condition on Chan-Paton factors, we show that three choice of gauge group are possible for heterotic M(atrix) theory: SO(2N), SO(2N+1) or USp(2N). By examining area-preserving diffeomorphism that underlies the M(atrix) theory, we find that each choices of gauge group restricts possible topologies of two-branes. The result suggests that only the choice of SO(2N) or SO(2N+1) groups allows open two-branes, hence, relevant to heterotic M(atrix) theory. We show that requirement of both local vacuum energy cancellation and of worldsheet anomaly cancellation of resulting heterotic string identifies supersymmetric twisted sector spectra with sixteen fundamental representation spinors from each of the two fixed points. Twisted open and closed two-brane configurations are obtained in the large N limit.

hep-th↗

arXiv1997

Absorption and Recoil of Fundamental String by D-String

Inclusive absorption cross section of fundamental IIB string to D-string is calculated perturbatively. The leading order result agrees with estimate based on stringy Higgs mechanism via Cremmer-Scherk coupling. It is argued that the subleading order correction is dominated by purely planar diagrams in the large mass limit. The correction represents conversion of binding energy into local recoil process of the fundamental string and D-string bound state. We show their presence explicitly in the next leading order.

hep-th↗

arXiv1997

Heterotic M(atrix) Strings and Their Interactions

Following recent proposal of Dijkgraaf, Verlinde and Verlinde, we show that the M(atrix) theory compactified on $S_1/Z_2$ provides with a non-perturbative description of second-quantized light-cone heterotic string. This so-called heterotic M(atrix) string theory is defined by two-dimensional (8,0) supersymmetric chiral gauge theory with gauge group SO(2N) in the large N limit. We argue that at strong coupling fixed point the chiral gauge theory flows to a (8,0) superconformal field theory defined via $S_N$ symmetric product space orbifold. We show that the leading order correction to the strong coupling expansion corresponds to a unique irrelevant operator of scaling dimension three and describes joining and splitting cubic interactions of light-cone heterotic string. We also speculate on M(atrix) description of bosonic strings via dimensional reduction of d=26 Yang-Mills theory.

hep-th↗

arXiv1996

Classical and Quantum Aspects of BPS Black Holes in N=2, D=4 Heterotic String Compactifications

We study classical and quantum aspects of D=4, N=2 BPS black holes for T_2 compactification of D=6, N=1 heterotic string vacua. We extend dynamical relaxation phenomena of moduli fields to background consisting of a BPS soliton or a black hole and provide a simpler but more general derivation of the Ferrara-Kallosh's extremized black hole mass and entropy. We study quantum effects to the BPS black hole mass spectra and to their dynamical relaxation. We show that, despite non-renormalizability of string effective supergravity, quantum effect modifies BPS mass spectra only through coupling constant and moduli field renormalizations. Based on target-space duality, we establish a perturbative non-renormalization theorem and obatin exact BPS black hole mass and entropy in terms of renormalized string loop-counting parameter and renormalized moduli fields. We show that similar conclusion holds, in the large T_2 limit, for leading non- perturbative correction. We finally discuss implications to type-I and type-IIA Calabi -Yau black holes.

hep-th↗

arXiv1996

Recent Progress in String Inflationary Cosmology

Super--inflation driven by dilaton/moduli kinetic energy is naturally realized in compactified string theory. Discussed are selected topics of recent development in string inflationary cosmology: kinematics of super-inflation, graceful exit triggered by quantum back reaction, and clasical and quantum power spectra of density and metric perturbations.

hep-th↗

arXiv1996

$V_{ub}$ from the Hadron Energy Spectrum in Inclusive Semileptonic B Decays

A measurement of the hadron energy spectrum in inclusive semileptonic $B$ decays is proposed as a viable method for extracting $|V_{ub}|$. Compared to the traditional energy spectrum of the charged lepton, the hadron energy spectrum exhibits kinematical advantages such as a wider energy window and a larger signal branching fraction. It is emphasized that the hadron energy spectrum method is most suited for symmetric $B$ factories, such as CLEO. The hadron energy distribution is calculated in the approach of the Altarelli et al. model and of the heavy-quark effective field theory. In both methods, perturbative QCD corrections, the Fermi motion of the $b$-quark in the $B$-meson, and the recoil momentum of the $B$-meson (stemming from the $Υ(4S)$ resonance) are taken into account. We have found excellent agreement between the spectra calculated in both methods, especially in the relevant kinematical region below the charmed meson threshold. The theoretical error to $|V_{ub}|$, which is dominated by the uncertainty of the $b$-quark mass, is estimated to be at the $\pm 12 \%$ level.

hep-ph↗

arXiv1996

Higher-Order Gravitational Couplings and Modular Forms in $N=2,D=4$ Heterotic String Compactifications

The restrictions of target--space duality are imposed at the perturbative level on the holomorphic Wilsonian couplings that encode certain higher-order gravitational interactions in $N=2, D=4$ heterotic string compactifications. A crucial role is played by non-holomorphic corrections. The requirement of symplectic covariance and an associated symplectic anomaly equation play an important role in determining their form. For models which also admit a type-II description, this equation coincides with the holomorphic anomaly equation for type-II compactifications in the limit that a specific Kähler-class modulus grows large. We explicitly evaluate some of the higher-order couplings for a toroidal compactification with two moduli $T$ and $U$, and we express them in terms of modular forms.

hep-th↗

arXiv1996

Cosmological Quantum String Vacua and String-String Duality

Implications of string-string dualities to cosmological string vacua are discussed. Cosmological vacua of classical string theories comprise of disjoint classses mapped one another by scale-factor T-duality. Each classes are, however, afflicted with initial/final cosmological singularities. It is argued that quantum string theories and string-string dualities dramatically resolve these cosmological singularities out so that disjoint classical cosmological vacua are continuously connected in a unified manner. A natural inflationary cosmology follows from this.

hep-th↗

arXiv1996

Back Reaction and Graceful Exit in String Inflationary Cosmology

Classical string cosmology consists of two branches related to each other by scale-factor duality: a super-inflation branch and a Friedmann-Robertson-Walker (FRW) branch. Curvature and string coupling singularity separates the two branches, hence posing `graceful exit problem' to super-inflationary string cosmology. In an exactly soluble two-dimensional compactification model it is shown that quantum back reaction retards curvature and string coupling growth and connects the super-inflation branch to the FRW branch without encountering a singularity. This may offer an attractive solution to the `graceful exit problem' in string inflationary cosmology.

hep-th↗

arXiv1996

BPS Spectra and Non--Perturbative Couplings in N=2,4 Supersymmetric String Theories

We study the BPS spectrum in $D=4, N=4$ heterotic string compactifications, with some emphasis on intermediate $N=4$ BPS states. These intermediate states, which can become short in $N=2$ compactifications, are crucial for establishing an $S-T$ exchange symmetry in $N=2$ compactifications. We discuss the implications of a possible $S-T$ exchange symmetry for the $N=2$ BPS spectrum. Then we present the exact result for the 1-loop corrections to gravitational couplings in one of the heterotic $N=2$ models recently discussed by Harvey and Moore. We conjecture this model to have an $S-T$ exchange symmetry. This exchange symmetry can then be used to evaluate non-perturbative corrections to gravitational couplings in some of the non-perturbative regions (chambers) in this particular model and also in other heterotic models.

hep-th↗

arXiv1994

Instanton Contribution to $B \rightarrow X_u e \bar ν$ Decay

We study instanton effects on inclusive semileptonic $b \rightarrow u$ decay using the heavy quark effective field theory and the operator product expansion. The effect contributes not only to the hadronic matrix element but also to the coefficient functions in the operator product expansion. We find that the coefficient function is singular near the boundaries of the phase space. In order to use perturbative QCD reliably, it is necessary to introduce smearing near the boundary. However the instanton contribution to $b \rightarrow c$ decay seems negligibly small.

hep-ph↗

arXiv1993

3 Into 2 Doesn't Go: (almost) chiral gauge theory on the lattice

Kaplan recently proposed a novel lattice chiral gauge theory in which the bare theory is defined on $(2n+1)$-dimensions, but the continuum theory emerges in $2n$-dimensions. We explore whether the resulting theory reproduces all the features of continuum chiral gauge theory in the case of two-dimensional axial Schwinger model. We find that one can arrange for the two-dimensional perturbation expansion to be reproduced successfully. However, the theory fails to reproduce the 2-dimensional fermion nonconservation.

hep-lat↗

arXiv1993

Instanton Effects in Supergravity Theories

Non-perturbative effects of instanton-like solutions are studied within the framework of supergravity theories with field-dependent gauge functions. Fermionic zero modes are constructed and some typical correlation functions are evaluated. The effects of instantons are very similar to those in globally supersymmetric theories: they preserve supersymmetry while breaking a chiral $U(1)$ symmetry. Non-perturbative amplitudes receive corrections which are suppressed at large distances.

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