119171894
The Liouville geometry of = 2 instantons and the moduli of punctured spheres
We propose that the = 2 SYM instanton moduli space maps to the one of punctured spheres, in the framework of the Liouville F-models. This leads to a bilinear recursion relation for the instanton contributions, resembling Hurwitz numbers, and predicts the asymptotic form of the GW invariants. The map is interpreted in the frameworks of the geometric engineering approach to the gauge theory, i.e. the topological A-model, and of the noncritical string theory. We speculate on the extension to the gravitational background and its relation to the uniformization program. Finally, we show an intriguing analogy with the gravitational version of the SU(2) self-dual YM equations where surprisingly the same Hauptmodule of the SW solution appears.
13930773
Quantum Fusion of Strings (Flux Tubes) and Domain Walls
We consider formation of composite strings and domain walls as a result of fusion of two elementary objects (elementary strings in the first case and elementary walls in the second) located at a distance from each other. The tension of the composite object T{sub 2} is assumed to be less than twice the tension of the elementary object T{sub 1}, so that bound states are possible. If in the initial state the distance d between the fusing strings or walls is much larger than their thickness and satisfies the conditions T{sub 1}d{sup 2}>>1 (in the string case) and T{sub 1}d{sup 3}>>1 (in the wall case), the problem can be fully solved quasiclassically. The fusion probability is determined by the first, 'under the barrier' stage of the process. We find the bounce configuration and its extremal action S{sub B}. In the wall problem e{sup -S{sub B}} gives the fusion probability per unit time per unit area. In the string case, due to a logarithmic infrared divergence, the problem is well formulated only for finite-length strings. The fusion probability per unit time can be found in the limit in which the string length is much larger than the distance between two mergingmore » strings.« less
119514504
Hopf Skyrmion in QCD with adjoint quarks
We consider a modification of QCD in which conventional fundamental quarks are replaced by Weyl fermions in the adjoint representation of the color SU(N). In the case of two flavors the low-energy chiral Lagrangian is that of the Skyrme-Faddeev model. The latter supports topologically stable solitons with mass scaling as N{sup 2}. Topological stability is due to the existence of a nontrivial Hopf invariant in the Skyrme-Faddeev model. Our task is to identify, at the level of the fundamental theory, adjoint QCD, an underlying reason responsible for the stability of the corresponding hadrons. We argue that all 'normal' mesons and baryons, with mass O(N{sup 0}), are characterized by (-1){sup Q}(-1){sup F}=1, where Q is a conserved charge corresponding to the unbroken U(1) surviving in the process of the chiral symmetry breaking (SU(2){yields}U(1) for two adjoint flavors). Moreover, F is the fermion number (defined mod 2 in the case at hand). We argue that there exist exotic hadrons with mass O(N{sup 2}) and (-1){sup Q}(-1){sup F}=-1. They are in one-to-one correspondence with the Hopf Skyrmions. The transition from nonexotic to exotic hadrons is due to a shift in F, namely F{yields}F-H where H is the Hopf invariant. To detect this phenomenonmore » we have to extend the Skyrme-Faddeev model by introducing fermions.« less
118506146
Instanton bags, high density holographic QCD, and chiral symmetry restoration
We describe the simplest example of an instanton bag in Euclidean space. It consists of a monopole wall and a Kaluza-Klein monopole wall, lifted to one higher dimension, trapping the instanton charge in the middle. This object has finite instanton density in a three-dimensional volume. 
Baryon physics in holographic QCD models gets translated into a multi-instanton problem in the bulk, and a state with a high density baryonic charge consists of a non-diluted multi-instanton solution. The instanton bag is a good candidate for this high-density state. We compute its parameters via moduli stabilization. Chiral symmetry restoration is exhibited by this state, and it is a direct consequence of its non-diluted features.
16025103
The Holomorphic Tension of Nonabelian Vortices and the Quark = Dual-Quark Condensate
We continue the work hep-th/0411075 considering here the case of degenerate masses. A nonabelian vortex arises in r-vacua upon the breaking by a superpotential for the adjoint field. The holomorphic tension, equal to the dual-quark condensate, is found to be exactly equal to the quark condensate. We explain this equality as a consequence of the invariance of the BPS tension along the Higgs branch.
118471919
Skyrmions in Yang-Mills theories with massless adjoint quarks
Dynamics of SU(N{sub c}) Yang-Mills theories with N{sub f} adjoint Weyl fermions is quite different from that of SU(N{sub c}) gauge theories with fundamental quarks. The symmetry breaking pattern is SU(N{sub f}){yields}SO(N{sub f}). The corresponding sigma model supports Skyrmions whose microscopic identification is not immediately clear. We address this issue as well as the issue of the Skyrmion stability. The case of N{sub f}=2 had been considered previously. Here we discuss N{sub f}{>=}3. We discuss the coupling between the massless Goldstone bosons and massive composite fermions [with mass O(N{sub c}{sup 0})] from the standpoint of the low-energy chiral sigma model. We derive the Wess-Zumino-Novikov-Witten term and then determine Skyrmion statistics. We also determine their fermion number (mod 2) and observe an abnormal relation between the statistics and the fermion number. This explains the Skyrmion stability. In addition, we consider another microscopic theory--SO(N{sub c}) Yang-Mills with N{sub f} Weyl fermions in the vectorial representation--which has the same chiral symmetry breaking pattern and the same chiral Lagrangian. We discuss distinctive features of these two scenarios.
59482524
Measurement of Drift Velocity in the CMS Barrel Muon Chambers at the CMS Magnet Test Cosmic Challenge
This note reports the results of the analysis performed on the data collected by the CMS Barrel Muon system during the Magnet Test-Cosmic Challenge, aimed to study the Drift Tube chambers behavior at the nominal value of the CMS magnetic field. In particular, the analysis is devoted to the study of the drift velocity in the various equipped regions of the apparatus. It is shown that the drift velocity is significantly affected by the presence of a residual magnetic field in the chamber volume only in the innermost stations, MB1, of Wheel+2; where the maximal variation inside the chamber is of 4 percent, which does not prevent a good functionality of the DT trigger even in this most critical region.