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Satoshi Iso

Publications and source records attributed to Satoshi Iso.

At least 73 records · Page 4Linked to original sources
arXiv2009

Construction of a topological charge on fuzzy S^2 x S^2 via Ginsparg-Wilson relation

We construct a topological charge of gauge field configurations on a fuzzy S^2xS^2 by using a Dirac operator satisfying the Ginsparg-Wilson relation. The topological charge defined on the fuzzy S^2xS^2 can be interpreted as a noncommutative (or matrix) generalization of the 2nd Chern character on S^2xS^2. We further calculate the number of chiral zero modes of the Dirac operator in topologically nontrivial gauge configurations. Generalizations of our formulation to fuzzy (S^2)^k are also discussed.

hep-th↗
arXiv2009

The minimal B-L model naturally realized at TeV scale

In a previous paper, we have proposed the minimal B-L extended standard model as a phenomenologically viable model that realizes the Coleman-Weinberg-type breaking of the electroweak symmetry. Assuming the classical conformal invariance and stability up to the Planck scale, we will show in this paper that the model naturally predicts TeV scale B-L breaking as well as a light standard-model singlet Higgs boson and light right-handed neutrinos around the same energy scale. We also study phenomenology and detectability of the model at the Large Hadron Collider (LHC) and the International Linear Collider (ILC).

hep-ph↗
arXiv2009

Classically Conformal B-L extended Standard Model

Under a hypothesis of classically conformal theories, we investigate the minimal B-L extended Standard Model, which naturally provides the seesaw mechanism for explaining tiny neutrino masses. In this setup, the radiative gauge symmetry breaking is successfully realized in a very simple way: The B-L gauge symmetry is broken through the conformal anomaly induced by quantum corrections in the Coleman-Weinberg potential. Associated with this B-L symmetry breaking, the Higgs mass parameter is dynamically generated, by which the electroweak symmetry breaking is triggered. We find that a wide range of parameter space can satisfy both the theoretical and experimental requirements.

hep-ph↗
arXiv2009

Hawking Radiation via Higher-spin Gauge Anomalies

We give a higher-spin generalization of the anomaly method for the Hawking radiation from black holes. In the paper arXiv:0710.0453 higher-spin generalizations of the gauge (and gravitational) anomalies in d=2 were obtained. By applying these anomalies to black hole physics, we derive the higher moments of the Hawking fluxes. We also give a higher-spin generalization of the trace anomaly method by Christensen and Fulling.

hep-th↗
arXiv2008

Scaling limit of N=6 superconformal Chern-Simons theories and Lorentzian Bagger-Lambert theories

We show that the N=8 superconformal Bagger-Lambert theory based on the Lorentzian 3-algebra can be derived by taking a certain scaling limit of the recently proposed N=6 superconformal U(N)xU(N) Chern-Simons-matter theories at level (k, -k). The scaling limit (and Inonu-Wigner contraction) is to scale the trace part of the bifundamental fields as X_0 -> λ^{-1} X_0 and an axial combination of the two gauge fields as B_μ -> λB_μ. Simultaneously we scale the level as k -> λ^{-1} k and then take λ-> 0 limit. Interestingly the same constraint equation \partial^2 X_0=0 is derived by imposing finiteness of the action. In this scaling limit, M2-branes are located far from the origin of C^4/Z_k compared to their fluctuations and Z_k identification becomes a circle identification. Hence the scaled theory describes N=8 supersymmetric theory of 2-branes with dynamical coupling. The coupling constant is promoted to a space-time dependent SO(8) vector X_0^I and we show that the scaled theory has a generalized conformal symmetry as well as manifest SO(8) with the transformation of the background fields X_0^I.

hep-th↗
arXiv2008

Index theorem in spontaneously symmetry-broken gauge theories on a fuzzy 2-sphere

We consider a gauge-Higgs system on a fuzzy 2-sphere and study the topological structure of gauge configurations, when the U(2) gauge symmetry is spontaneously broken to U(1) times U(1) by the vev of the Higgs field. The topology is classified by the index of the Dirac operator satisfying the Ginsparg-Wilson relation, which turns out to be a noncommutative analog of the topological charge introduced by 't Hooft. It can be rewritten as a form whose commutative limit becomes the winding number of the Higgs field. We also study conditions which assure the validity of the formulation, and give a generalization of the admissibility condition. Finally we explicitly calculate the topological charge of a one-parameter family of configurations.

hep-th↗
arXiv2008

Generalized Conformal Symmetry and Recovery of SO(8) in Multiple M2 and D2 Branes

We investigate conformal symmetries of the Aharony-Bergman-Jafferis-Maldacena (ABJM) theory for multiple M2 branes and the Lorentzian Bagger-Lambert-Gustavsson (L-BLG) theory which can be obtained by taking a scaling limit k (>>N) -> \infty of the ABJM theory. The conformal symmetry is maintained in the L-BLG by considering general space-time varying solutions to the constraint equations. The dual geometry is reduced to d=10 AdS4 x CP3 in the scaling limit and has the same conformal symmetry. The curvature radius R satisfies l_{11p} << l_{10p} << R << l_s (l_{dp} and l_s are the d-dimensional Planck lengths and the string scale), and the theory is in a region where an α' expansion is not valid. We also study how the SO(8) covariance is recovered in the AdS4 x CP3 geometry by taking the scaling limit.

hep-th↗
arXiv2008

Janus field theories from multiple M2 branes

Based on the recent proposal of N=8 superconformal gauge theories of the multiple M2 branes, we derive (2+1)-dimensional supersymmetric Janus field theories with a space-time dependent coupling constant. From the original Bagger-Lambert model, we get a supersymmetric field theory with a similar action to the N D2 branes, but the coupling varies with the space-time as a function of the light-cone coordinate, g(t+x). Half of the supersymmetries can be preserved. We further investigate the M2 brane action deformed by mass and Myers-like terms. In this case, the final YM action is deformed by mass and Myers terms and the coupling behaves as exp(μx) where μis a constant mass parameter. Weak coupling gauge theory is continuously changed to strong coupling in the large x region.

hep-th↗
arXiv2008

Anomalies, Hawking Radiations and Regularity in Rotating Black Holes

This is an extended version of our previous letter hep-th/0602146. In this paper we consider rotating black holes and show that the flux of Hawking radiation can be determined by anomaly cancellation conditions and regularity requirement at the horizon. By using a dimensional reduction technique, each partial wave of quantum fields in a d=4 rotating black hole background can be interpreted as a (1+1)-dimensional charged field with a charge proportional to the azimuthal angular momentum m. From this and the analysis gr-qc/0502074, hep-th/0602146 on Hawking radiation from charged black holes, we show that the total flux of Hawking radiation from rotating black holes can be universally determined in terms of the values of anomalies at the horizon by demanding gauge invariance and general coordinate covariance at the quantum level. We also clarify our choice of boundary conditions and show that our results are consistent with the effective action approach where regularity at the future horizon and vanishing of ingoing modes at r=\infty are imposed (i.e. Unruh vacuum).

hep-th↗
arXiv2008

Quantum Anomalies at Horizon and Hawking Radiations in Myers-Perry Black Holes

A new method has been developed recently to derive Hawking radiations from black holes based on considerations of gravitational and gauge anomalies at the horizon gr-qc/0502074 hep-th/0602146. In this paper, we apply the method to Myers-Perry black holes with multiple angular momenta in various dimensions by using the dimensional reduction technique adopted in the case of four-dimensional rotating black holes hep-th/0606018.

hep-th↗
arXiv2007

Tuning phase transition between quantum spin Hall and ordinary insulating phases

An effective theory is constructed for analyzing a generic phase transition between the quantum spin Hall and the insulator phases. Occurrence of degeneracies due to closing of the gap at the transition are carefully elucidated. For systems without inversion symmetry the gap-closing occurs at \pm k_0(\neq G/2) while for systems with inversion symmetry, the gap can close only at wave-numbers k=G/2, where G is a reciprocal lattice vector. In both cases, following a unitary transformation which mixes spins, the system is represented by two decoupled effective theories of massive two-component fermions having masses of opposite signs. Existence of gapless helical modes at a domain wall between the two phases directly follows from this formalism. This theory provides an elementary and comprehensive phenomenology of the quantum spin Hall system.

cond-mat.mes-hall↗
arXiv2007

Higher-spin Gauge and Trace Anomalies in Two-dimensional Backgrounds

Two-dimensional quantum fields in electric and gravitational backgrounds can be described by conformal field theories, and hence all the physical (covariant) quantities can be written in terms of the corresponding holomorphic quantities. In this paper, we first derive relations between covariant and holomorphic forms of higher-spin currents in these backgrounds, and then, by using these relations, obtain higher-spin generalizations of the trace and gauge (or gravitational) anomalies up to spin 4. These results are applied to derive higher-moments of Hawking fluxes in black holes in a separate paper arXiv:0710.0456.

hep-th↗
arXiv2007

Higher-spin Currents and Thermal Flux from Hawking Radiation

Quantum fields near black hole horizons can be described in terms of an infinite set of d=2 conformal fields. In this paper, by investigating transformation properties of general higher-spin currents under a conformal transformation, we reproduce the thermal distribution of Hawking radiation in both cases of bosons and fermions. As a byproduct, we obtain a generalization of the Schwarzian derivative for higher-spin currents.

hep-th↗
arXiv2007

Fluxes of Higher-spin Currents and Hawking Radiations from Charged Black Holes

This is an extended version of the previous paper (hep-th/0701272). Quantum fields near horizons can be described in terms of an infinite set of two-dimensional conformal fields. We first generalize the method of Christensen and Fulling to charged black holes to derive fluxes of energy and charge. These fluxes can be obtained by employing a conformal field theory technique. We then apply this technique to obtain the fluxes of higher-spin currents and show that the thermal distribution of Hawking radiation from a charged black hole can be completely reproduced by investigating transformation properties of the higher-spin currents under conformal and gauge transformations.

hep-th↗
arXiv2007

Ginsparg-Wilson Dirac operator in the monopole backgrounds on the fuzzy 2-sphere

In the previous papers, we studied the 't Hooft-Polyakov (TP) monopole configurations in the U(2) gauge theory on the fuzzy 2-sphere,and showed that they have nonzero topological charge in the formalism based on the Ginsparg-Wilson (GW) relation. In this paper, we will show an index theorem in the TP monopole background, which is defined in the projected space, and provide a meaning of the projection operator. We also extend the index theorem to general configurations which do not satisfy the equation of motion, and show that the configuration space can be classified into the topological sectors. We further calculate the spectrum of the GW Dirac operator in the TP monopole backgrounds, and consider the index theorem in these cases.

hep-th↗
arXiv2006

Hawking Radiation from Charged Black Holes via Gauge and Gravitational Anomalies

Extending gr-qc/0502074, we show that in order to avoid a breakdown of general covariance and gauge invariance at the quantum level the total flux of charge and energy in each outgoing partial wave of a charged quantum field in a Reissner-Nordstrom black hole background must be equal to that of a (1+1) dimensional blackbody at the Hawking temperature with the appropriate chemical potential.

hep-th↗
arXiv2005

Fermionic Backgrounds and Condensation of Supergravity Fields in IIB Matrix Model

In a previous paper hep-th/0410182 we constructed wave functions and vertex operators for massless supergravity fields in type IIB matrix model by expanding supersymmetric Wilson line operators. In this paper we consider fermionic backgrounds and condensation of supergravity fields in IIB matrix model by using these wave functions. We start from the type IIB matrix model in a flat background whose matrix size is $(N+1) \times (N+1)$, or equivalently the effective action for $(N+1)$ D-instantons. We then calculate an effective action for $N$ D-instantons by integrating out one D-instanton (which we call a mean-field D-instanton) with an appropriate wave function and show that various terms can be induced corresponding to the choice of the wave functions. In particular, a Chern-Simons-like term is induced when the mean-field D-instanton has a wave function of the antisymmetric tensor field. A fuzzy sphere becomes a classical solution to the equation of motion for the effective action. We also give an interpretation of the above wave functions from the string theory side as overlaps of the D-instanton boundary state with closed string massless states in the Green-Schwarz formalism.

hep-th↗