类矢标准模型中规范相互作用与引力的统一

提出在无轻子的超对称类矢标准模型中,在规范作用双圈修正和引力单圈弦修正下,研究规范耦合和引力之间的统一问题.结果表明,需要两个中间质量标度.其中低质量标度在未来实验室可到达的范围内,高的质量标度约为10¹⁶GeV.     

Dynamics of N = 2 supersymmetric gauge theories in three dimensions

We study the structure of the moduli spaces of vacua and superpotentials of N = 2 supersymmetric gauge theories in three dimensions. By analyzing the instanton corrections, we compute the exact superpotentials and determine the quantum Coulomb and Higgs branches of the theories in the weak coupling regions. We find candidates for non-trivial N = 2 superconformal field theories at the singularities of the moduli spaces. The analysis is carried out explicitly for gauge groups U(N_c) and SU(N_c) with N _f flavors. We show that the field theory results are in complete agreement with the intersecting branes picture. We also compute the exact superpotentials for arbitrary gauge groups and arbitrary matter content.     

Holographic Insulator/Superconductor Phase Transition in Born–Infeld Electrodynamics

We study holographic insulator/superconductor phase transition in the framework of Born–Infeld electrodynamics both numerically and analytically. First we numerically study the efects of the Born–Infeld electrodynamics on the phase transition, find that when the Born–Infeld parameter increases, the critical chemical potential keeps invariant but the gap frequency becomes larger. Then we employ the variational method for the Sturm–Liouville eigenvalue problem to study the phase transition analytically. The analytical results obtained are found to be consistent with the numerical results.     

Holographic Insulator/Superconductor Phase Transition in Born-Infeld Electrodynamics

We study holographic insulator/superconductor phase transition in the framework of Born-Infeld electrodynamics both numerically and analytically. First we numerically study the effects of the Born-Infeld electrodynamics on the phase transition, find that when the Born-Infeld parameter increases, the critical chemical potential keeps invariant but the gap frequency becomes larger. Then we employ the variational method for the Sturm-Liouville eigenvalue problem to study the phase transition analytically. The analytical results obtained are found to be consistent with the numerical results.     

Charged surfaces and the analyticity properties of the string tension in lattice gauge theories

A method to prove the fact that the string tension in strongly coupled lattice gauge theories is of the form =–log +, where is an analytic function of the inverse coupling =1/g², is presented. Its relation to random surface methods, in particular to the work of Debrushin and Holický, Kotecký, and Zahradník, is discussed.This paper is based on a talk presented at the conference on Statistical Mechanics of Phase Transitions—Mathematical and Physical Aspects, Trebon, September 1–6, 1986.     

General theory of renormalization of gauge theories in nonlinear gauges

We discuss the general theory of renormalization of unbroken gauge theories in the nonlinear gauges in which the gauge-fixing term is of the form We show that higher loop renormalization modifiesfα [A] to contain ghost terms of the form and show how the corresponding ghost terms are deduced fromfα [A, c, c] uniquely. We show that the theory can be renormalized while preserving a modified form of BRS invariance by multiplicative and independent renormalizations onA, c, g, η, ζ, τ. We briefly discuss the independence of the renormalized S-matrix from η,ζ, τ.     

Gribov ambiguity in gauge theories

Gribov ambiguity in gauge field theories is discussed and it is shown that such an ambiguity exists even for Abelian theories in covariant gauge at finite temperature. Both geometric and algebraic proofs are presented. In view of the importance of non-perturbative methods, some special gauges are given in which such ambiguities do not exist or are not relevant. The significance of these in the study of confinement in QCD is pointed out.     

A Twistorial Approach to Integrability in SYM

While the achievements in the study of Super Yang‐Mills through the application of integrability are impressive, the precise origins of the exact solvability remain shrouded in mystery. In this note, we propose that viewing the problem through the lens of twistor theory should help to clarify the reasons for integrability. We illustrate the power of this approach by rederiving the model's one‐loop spin chain dilatation operator in the SO(6) sector.     

正则Ward恒等式和Abel规范理论中动力学质量的产生

文中基于约束Hamilton系统理论用Faddeev-Senjanovic路径积分量子化方法,重新讨论了Cornwall-Norton和Jackiw-Johnson模型的量子化,导出了这两个系统的正则Ward恒等式,利用导出的正则Ward恒等式,得到了包括费米子和束缚态的质量谱.所得的结果与其他方法导出的结果相同     

(MS)SM‐like models on smooth Calabi‐Yau manifolds from all three heterotic string theories

We perform model searches on smooth Calabi‐Yau compactifications for both the supersymmetric E₈ × E₈ and SO(32) as well as for the non‐supersymmetric SO(16) × SO(16) heterotic strings simultaneously. We consider line bundle backgrounds on both favorable CICYs with relatively small h₁₁ and the Schoen manifold. Using Gram matrices we systematically analyze the combined consequences of the Bianchi identities and the tree‐level Donaldson‐Uhlenbeck‐Yau equations inside the Kähler cone. In order to evaluate the model building potential of the three heterotic theories on the various geometries, we perform computer‐aided scans. We have generated a large number of GUT‐like models (up to over a few hundred thousand on the various geometries for the three heterotic theories) which become (MS)SM‐like upon using a freely acting Wilson line. For all three heterotic theories we present tables and figures summarizing the potentially phenomenologically interesting models which were obtained during our model scans.     

Two-Particle Irreducible Effective Action in Gauge Theories

The goal of this paper is to develop the formalism of the two-particle irreducible (2PI) (G. Baym (1962). Physical Review 127, 1391; H. D. Dahmen and G. Jona Lasino (1962). Nuovo Cimento A 52, 807; C. de Dominicis and P. Martin (1964). Journal of Mathematical Physics 5, 14; J. Luttinger and J. Ward (1960). Physical Review 118, 1417; B. Vanderheyden and G. Baym (1998). Journal of Statistical Physics 98, 843; B. Vanderheyden and G. Baym (2000). In Progress in Nonequilibrium Green's Functions, World Scientific, Singapore). (or Cornwall–Jackiw–Tomboulis (CJT) (J. Cornwall, R. Jackiw, and E. Tomboulis (1974). Physical Review D 10, 2428; U. Kraemmer and A. Rebhan (2004). Reports on Progress in Physics 67, 351; R. Norton and J. Cornwall (1975). Annals of Physics 91, 106) effective action (EA) in a way appropiate to its application to nonequilibrium gauge theories. We hope this review article will stimulate new work into this field.     

Towards a world‐sheet description of doubled geometry in string theory

Starting from a sigma‐model for a doubled target‐space geometry, we show that the number of target‐space dimensions can be reduced by half through a gauging procedure. We apply this formalism to a class of backgrounds relevant for double field theory, and illustrate how choosing different gaugings leads to string‐theory configurations T‐dual to each other. We furthermore discuss that given a conformal doubled theory, the reduced theories are conformal as well. As an example we consider the three‐dimensional WZW model and show that the only possible reduced backgrounds are the cigar and trumpet CFTs in two dimensions, which are indeed T‐dual to each other.     

Gauge coupling renormalization in AdS5

We present the relation of the 4-dimensional low energy gauge coupling and the 5-dimensional fundamental gauge coupling of bulk gauge boson in a slice of AdS₅, which is orbifolded byZ ₂ ×Z′₂. We calculate the full 1-loop corrections for the case of generic 5-dimensional scalar, Dirac fermion, and vector fields with arbitraryZ ₂×Z′₂. For the supersymmetric case, we obtain the result more easily by using the 4-dimensional effective supergravity approach.     

On semiclassical four‐point correlators in AdS5 × S5

Following the recent advances in the holographic calculation of n‐point correlation functions with two “heavy” (with large quantum numbers) states at strong coupling, we extend these findings by computing specific contributions to four‐point correlators of four heavy BMN operators in �� = 4 supersymmetric Yang–Mills theory.     

Field theory on a non‐commutative plane: a non‐perturbative study

The 2d gauge theory on the lattice is equivalent to the twisted Eguchi–Kawai model, which we simulated at N ranging from 25 to 515. We observe a clear large N scaling for the 1‐ and 2‐point function of Wilson loops, as well as the 2‐point function of Polyakov lines. The 2‐point functions agree with a universal wave function renormalization. The large N double scaling limit corresponds to the continuum limit of non‐commutative gauge theory, so the observed large N scaling demonstrates the non‐perturbative renormalizability of this non‐commutative field theory. The area law for the Wilson loops holds at small physical area as in commutative 2d planar gauge theory, but at large areas we find an oscillating behavior instead. In that regime the phase of the Wilson loop grows linearly with the area. This agrees with the Aharonov‐Bohm effect in the presence of a constant magnetic field, identified with the inverse non‐commutativity parameter. Next we investigate the 3d λϕ⁴ model with two non‐commutative coordinates and explore its phase diagram. Our results agree with a conjecture by Gubser and Sondhi in d = 4, who predicted that the ordered regime splits into a uniform phase and a phase dominated by stripe patterns. We further present results for the correlators and the dispersion relation. In non‐commutative field theory the Lorentz invariance is explicitly broken, which leads to a deformation of the dispersion relation. In one loop perturbation theory this deformation involves an additional infrared divergent term. Our data agree with this perturbative result. We also confirm the recent observation by Ambjø rn and Catterall that stripes occur even in d = 2, although they imply the spontaneous breaking of the translation symmetry.     

Hadron spectroscopy and structure from AdS/CFT

The AdS/CFT correspondence between conformal field theory and string states in an extended space-time has provided new insights into not only hadron spectra, but also their light-front wave functions. We show that there is an exact correspondence between the fifth-dimensional coordinate of anti-de Sitter space z and a specific impact variable ζ which measures the separation of the constituents within the hadron in ordinary space-time. This connection allows one to predict the form of the light-front wave functions of mesons and baryons, the fundamental entities which encode hadron properties and scattering amplitudes. A new relativistic Schr?dinger light-front equation is found which reproduces the results obtained using the fifth-dimensional theory. Since they are complete and orthonormal, the AdS/CFT model wave functions can be used as an initial ansatz for a variational treatment or as a basis for the diagonalization of the light-front QCD Hamiltonian. A number of applications of light-front wave functions are also discussed.     

p‐wave superconductors in dilaton gravity

In this paper, we study peculiar properties of p‐wave superconductors in dilaton gravity. The scale invariance of the bulk geometry is effectively broken due to the existence of a dilaton. By coupling the dilaton to the non‐Abelian gauge field, i.e., ‐1/4 e^{‐β Φ} F^a_μνF^aμν, we find that the dissipative conductivity of the normal phase decreases and approaches zero at the zero frequency as β increases. Intuitively, the system behaves more and more like an insulator. When the hairy solution is turned on, the system crosses a critical point to the superconducting phase. We find that the critical chemical potential decreases with the increasing of β and the maximum height of the conductivity is suppressed gradually which are consistent with our intuition for insulator/supercondutor transition.