Magnetization plateau in S=3/2 antiferromagnetic Heisenberg chain with anisotropy

The magnetization process of the S=3/2 antiferromagnetic Heisenberg chain with the single-ion anisotropy D at T=0 is investigated by the exact diagonalization of finite clusters and finite-size scaling analyses. It is found that a magnetization plateau appears at m=1/2 for $D>D_c=0.93 \pm 0.01$. The phase transition with respect to D at D_c is revealed to be the Kosterlitz-Thouless-type. The magnetization curve of the infinite system is also presented for some values of D.Comment: 4 pages, Revtex, with 5 eps figure

Non-BPS walls and their stability in 5d SUSY theory

We review recent work (hep-th/0404114) on non-BPS domain walls in $5d$ SUSY theory. An exact solution of non-BPS multi-walls is found in supersymmetric massive T*(CP1) model in five dimensions. The non-BPS multi-wall solution is found to have no tachyon. The N=1 supersymmetry preserved on the four-dimensional world volume of one wall is broken by the coexistence of the other wall. The supersymmetry breaking is exponentially suppressed as the distance between the walls increases.Comment: 4 pages, contribution to SUSY2004 Proceedings, some typos correcte

Non-BPS Walls and Their Stability in 5D Supersymmetric Theory

An exact solution of non-BPS multi-walls is found in supersymmetric massive T^\star(\mathbb{CP}^1) model in five dimensions. The non-BPS multi-wall solution is found to have no tachyon. Although it is only metastable under large fluctuations, we can give topological stability by considering a model with a double covering of the T^\star(\mathbb{CP}^1) target manifold. The {\cal N}=1 supersymmetry preserved on the four-dimensional world volume of one wall is broken by the coexistence of the other wall. The supersymmetry breaking is exponentially suppressed as the distance between the walls increases.Comment: 38 pages, 8 figures, references added, citation modified, final version to appear in NP

Effective Lagrangians on Domain Walls and Other Solitons

Maintaining the preserved supersymmetry helps to find the effective Lagrangian on the BPS background in gauge theories with eight supercharges. As concrete examples, we take 1/2 BPS domain walls. The Lagrangian is given in terms of the superfields with manifest four preserved supercharges and is expanded in powers of the slow-movement parameter lambda. The O(lambda^0) gives the superfield form of the BPS equations, whereas all the fluctuation fields follow at O(lambda^1). The effective Lagrangian is given by the density of the K"ahler potential which emerges automatically from the lambda expansion making four preserved supercharges manifest. More complete account of our method and applications is given in hep-th/0602289 in which the case of non-Abelian vortices is also worked out.Comment: 10 pages, Proceedings of the conference ``From Strings to LHC'

Localized non-Abelian gauge fields in non-compact extra-dimensions

Dynamical localization of non-Abelian gauge fields in non-compact flat $D$ dimensions is worked out. The localization takes place via a field-dependent gauge kinetic term when a field condenses in a finite region of spacetime. Such a situation typically arises in the presence of topological solitons. We construct four-dimensional low-energy effective Lagrangian up to the quadratic order in a universal manner applicable to any spacetime dimensions. We devise an extension of the $R_\xi$ gauge to separate physical and unphysical modes clearly. Out of the D-dimensional non-Abelian gauge fields, the physical massless modes reside only in the four-dimensional components, whereas they are absent in the extra-dimensional components. The universality of non-Abelian gauge charges holds due to the unbroken four-dimensional gauge invariance. We illustrate our methods with models in $D=5$ (domain walls), in $D=6$ (vortices), and in $D=7$.Comment: 42 pages, 9 figures, several references are adde

Localization of matter fields and non-Abelian gauge fields on domain walls

We propose a method for simultaneous localization of non-Abelian gauge fields and matter fields with minimal interaction on domain walls using $U(N)_c$ gauge theory with $SU(N)_{L}\times SU(N)_{R}\times U(1)_{A}$ flavor symmetry. Localization of non-Abelian fields is achieved using field-dependent gauge coupling. We find that effective Lagrangian up to second order of derivatives for low energy fluctuations resembles a chiral model from hadron physics with additional minimal interactions of pions with localized gauge fields together with nonlinear interactions of moduli fields. This result provides a step towards a realistic model building of brane-world scenario using topological solitons.Comment: 15 pages, 1 figure. to appear in Proceedings of the conference Integrable Systems and Quantum symmetries (ISQS-21); Prague, June 12-16 201

Localization of the Standard Model via Higgs mechanism and a finite electroweak monopole from non-compact five dimensions

We propose a minimal and self-contained model in non-compact flat five dimensions which localizes the Standard Model (SM) on a domain wall. Localization of gauge fields is achieved by the condensation of Higgs field via a Higgs dependent gauge kinetic term in five-dimensional Lagrangian. The domain wall connecting vacua with unbroken gauge symmetry drives the Higgs condensation which provides both electroweak symmetry breaking and gauge field localization at the same time. Our model predicts higher-dimensional interactions $|H|^{2n}(F_{\mu\nu})^2$ in the low-energy effective theory. This leads to two expectations: The one is a new tree-level contribution to $H \to \gamma\gamma$ ($H \to gg$) decay whose signature is testable in future LHC experiment. The other is a finite electroweak monopole which may be accessible to the MoEDAL experiment. Interactions of translational Nambu-Goldstone boson is shown to satisfy a low-energy theorem.Comment: 32 pages, 2 figure, v2: references added, typos corrected. v3: Almost final version to be published by PTEP. Evaluation of lower bound of KK quark masses is added. Appendix C is adde

BPS Multi-Walls in Five-Dimensional Supergravity

Exact BPS solutions of multi-walls are obtained in five-dimensional supergravity. The solutions contain 2n parameters similarly to the moduli space of the corresponding global SUSY models and have a smooth limit of vanishing gravitational coupling. The models are constructed as gravitational deformations of massive T^*CP^n nonlinear sigma models by using the off-shell formulation of supergravity and massive quaternionic quotient method with U(1)*U(1) gauging. We show that the warp factor can have at most single stationary point in this case. We also obtain BPS multi-wall solutions even for models which reduce to generalizations of massive T^*CP^n models with only U(1)^n isometry in the limit of vanishing gravitational coupling. At particular values of parameters, isometry of the quaternionic manifolds is enhanced.Comment: 33 pages, 9 figures, A paragraph and a reference is added to explain collective coordinates, A few typos corrected, Final version to appear in Phys. Re

Next Nearest-Neighbor Correlation Functions of the Spin-1/2 XXZ Chain at Critical Region

The correlation functions of the spin-1/2 XXZ spin chain in the ground state are expressed in the form of the multiple integrals. For -1< Delta <1, they were obtained by Jimbo and Miwa in 1996. Especially the next nearest-neighbour correlation functions are given as certain three-dimensional integrals. We shall show these integrals can be reduced to one-dimensional ones and thereby evaluate the values of the next nearest-neighbor correlation functions. We have also found that the remaining one-dimensinal integrals can be evaluated analytically, when nu = arccos(Delta)/pi is a rational number.Comment: 10 pages, 2 figure

Non-Abelian Gauge Field Localization on Walls and Geometric Higgs Mechanism

Combining the semi-classical localization mechanism for gauge fields with $N$ domain wall background in a simple $SU(N)$ gauge theory in five space-time dimensions we investigate the geometric Higgs mechanism, where a spontaneous breakdown of the gauge symmetry comes from splitting of domain walls. The mass spectra are investigated in detail for the phenomenologically interesting case $SU(5) \to SU(3)\times SU(2)\times U(1)$ which is realized on a split configuration of coincident triplet and doublet of domain walls. We derive a low energy effective theory in a generic background using the moduli approximation, where all non-linear interactions between effective fields are captured up to two derivatives. We observe novel similarities between domain walls in our model and D-branes in superstring theories.Comment: 45 pages, 8 figures, several references adde