On the ADHM construction of noncommutative U(2) k-instanton

The basic objects of the ADHM construction are reformulated in terms of elements of the $A_{\theta}(R^4)$ algebra of the noncommutative $R_{\theta}^4$ space. This new formulation of the ADHM construction makes possible the explicit calculus of the U(2) instanton number which is shown to be the product of a trace of finite rank projector of the Fock representation space of the algebra $A_{\theta}(R^4)$ times a noncommutative version of the winding number.Comment: 22 pages, new version to appear in Phys. Rev.

U(1)B−LU(1)_{B-L} extra-natural inflation with Standard Model on a brane

The interrelation between inflationary cosmology and new physics beyond the Standard Model (SM) is studied in a $U(1)_{B-L}$ extension of the SM embedded in a (4+1)-dimensional spacetime. In the scenario we study, the inflaton arises from the Wilson loop of the $U(1)_{B-L}$ gauge group winding an extra-dimensional cycle. Particular attention is paid to the coupling between the inflaton and SM particles that are confined on a brane localised in the extra dimension. We find that the inflaton decay channels are rather restricted in this scenario and the resulting reheating temperature is relatively low.Comment: 1+14 page

Supersymmetric reduced models with a symmetry based on Filippov algebra

Generalizations of the reduced model of super Yang-Mills theory obtained by replacing the Lie algebra structure to Filippov $n$-algebra structures are studied. Conditions for the reduced model actions to be supersymmetric are examined. These models are related with what we call \{cal N}_{min}=2 super $p$-brane actions.Comment: v3: In the previous versions we overlooked that Eq.(3.9) holds more generally, and missed some supersymmetric actions. Those are now included and modifications including a slight change in the title were made accordingly. 1+18 page

String solitons in the M5-brane worldvolume with a Nambu-Poisson structure and Seiberg-Witten map

We analyze BPS equations for string-like configurations derived from the M5-brane worldvolume action with a Nambu-Poisson structure constructed in arXiv:0804.3629, arXiv:0805.2898. We solve the BPS equations up to the first order in the parameter $g$ which characterizes the strength of the Nambu-Poisson bracket. We compare our solutions to previously constructed BPS string solitons in the conventional description of M5-brane in a constant three-form background via Seiberg-Witten map, and find agreement.Comment: v2: minor corrections, the title slightly changed. 10 pages. v3: some clarifying comment

Large N Reductions and Holography

The large $N$ reductions in gauge theories are identified with dimensional reductions with homogeneous distribution of the eigenvalues of the gauge field, and it is used to identify the corresponding closed string descriptions in the Maldacena duality. When one does not take the zero-radii limit, the large $N$ reductions are naturally extended to the equivalences between the gauge theories and the "generalized" reduced models, which naturally contain the notion of T-dual equivalence. In the dual gravitational description, T-duality relates two type IIB supergravity solutions, the near horizon geometry of D3-branes, and the near horizon geometry of D-instantons densely and homogeneously distributing on the dual torus. This is the holographic description of the generalized large $N$ reductions. A new technique for calculating correlation functions of local gauge invariant single trace operators from the reduced models is also given.Comment: REVTeX4 v2: simple mistake in eq.(1) corrected. footnote 4 in v1 expanded in the main body. conflicting notations for the dilaton below eq.(6) (in v1) fixed. 6 pages, 5 figures v3: corrected typo v4: presentation improved with explanations and clarifications. results unchanged. refs added. 8page

Calculating the Prepotential by Localization on the Moduli Space of Instantons

We describe a new technique for calculating instanton effects in supersymmetric gauge theories applicable on the Higgs or Coulomb branches. In these situations the instantons are constrained and a potential is generated on the instanton moduli space. Due to existence of a nilpotent fermionic symmetry the resulting integral over the instanton moduli space localizes on the critical points of the potential. Using this technology we calculate the one- and two-instanton contributions to the prepotential of SU(N) gauge theory with N=2 supersymmetry and show how the localization approach yields the prediction extracted from the Seiberg-Witten curve. The technique appears to extend to arbitrary instanton number in a tractable way.Comment: 24 pages, JHEP.cls, more references and extra discussion on N_F=2N cas

Non-Commutative Instantons and the Seiberg-Witten Map

We present several results concerning non-commutative instantons and the Seiberg-Witten map. Using a simple ansatz we find a large new class of instanton solutions in arbitrary even dimensional non-commutative Yang-Mills theory. These include the two dimensional ``shift operator'' solutions and the four dimensional Nekrasov-Schwarz instantons as special cases. We also study how the Seiberg-Witten map acts on these instanton solutions. The infinitesimal Seiberg-Witten map is shown to take a very simple form in operator language, and this result is used to give a commutative description of non-commutative instantons. The instanton is found to be singular in commutative variables.Comment: 26 pages, AMS-LaTeX. v2: the formula for the commutative description of the Nekrasov-Schwarz instanton corrected (sec. 4). v3: minor correction

More on the Nambu-Poisson M5-brane Theory: Scaling limit, background independence and an all order solution to the Seiberg-Witten map

We continue our investigation on the Nambu-Poisson description of M5-brane in a large constant C-field background (NP M5-brane theory) constructed in Refs.[1, 2]. In this paper, the low energy limit where the NP M5-brane theory is applicable is clarified. The background independence of the NP M5-brane theory is made manifest using the variables in the BLG model of multiple M2-branes. An all order solution to the Seiberg-Witten map is also constructed.Comment: expanded explanations, minor corrections and typos correcte

Noncommutative U(1) Instantons in Eight Dimensional Yang-Mills Theory

We study the noncommutative version of the extended ADHM construction in the eight dimensional U(1) Yang-Mills theory. This construction gives rise to the solutions of the BPS equations in the Yang-Mills theory, and these solutions preserve at least 3/16 of supersymmetries. In a wide subspace of the extended ADHM data, we show that the integer $k$ which appears in the extended ADHM construction should be interpreted as the $D4$-brane charge rather than the $D0$-brane charge by explicitly calculating the topological charges in the case that the noncommutativity parameter is anti-self-dual. We also find the relationship with the solution generating technique and show that the integer $k$ can be interpreted as the charge of the $D0$-brane bound to the $D8$-brane with the $B$-field in the case that the noncommutativity parameter is self-dual.Comment: 22 page

Quasi-localized states on noncommutative solitons

We consider noncommutative gauge theories which have zero mass states propagating along both commutative and noncommutative dimensions. Solitons in these theories generically carry U(m) gauge group on their world-volume. From the point of view of string theory, these solitons correspond to ``branes within branes''. We show that once the world-volume U(m) gauge theory is in the Higgs phase, light states become quasi-localized, rather than strictly localized on the soliton, i.e. they mix with light bulk modes and have finite widths to escape into the noncommutative dimensions. At small values of U(m) symmetry breaking parameters, these widths are small compared to the corresponding masses. Explicit examples considered are adjoint scalar field in the background of a noncommutative vortex in U(1)-Higgs theory, and gauge fields in instanton backgrounds in pure gauge noncommutative theories.Comment: 27 pages, references and comments added, final version to appear in JHE