1207 research outputs found
Sort by
Electrically charged finite energy solutions of an SO(5) and an SU(3) Higgs–Chern–Simons-Yang–Mills–Higgs system in 3+1 dimensions
Get PDFWe study spherically symmetric finite energy solutions of two Higgs-Chern-Simons–Yang-Mills-Higgs (HCS-YMH) models in 3 + 1 dimensions, one with gauge group SO(5) and the other with SU (3). The Chern-Simons (CS) densities are defined in terms of both the Yang-Mills (YM) and Higgs fields and the choice of the two gauge groups is made so they do not vanish. The solutions of the SO(5) model carry only electric charge and zero magnetic charge, while the solutions of the SU (3) model are dyons carrying both electric and magnetic charges like the Julia-Zee (JZ) dyon. Unlike the latter however, the electric charge in both models receives an important contribution from the CS dynamics. We pay special attention to the relation between the energies and charges of these solutions. In contrast with the electrically charged JZ dyon of the Yang-Mills-Higgs (YMH) system, whose mass is larger than that of the electrically neutral (magnetic monopole) solutions, the masses of the electrically charged solutions of our HCS-YMH models can be smaller than their electrically neutral counterparts in some parts of the parameter space. To establish this is the main task of this work, which is performed by constructing the HCS-YMH solutions numerically. In the case of the SU (3) HCS-YMH, we have considered the question of angular momentum, and it turns out that it vanishes
Generalized dyons and magnetic dipoles: The issue of angular momentum
Get PDFIt is known that a non-Abelian magnetic monopole cannot rotate globally (although it may possess a nonzero angular momentum density). At the same time, the total angular momentum of a magnetic dipole equals the electric charge. In this work we question the generality of these results by considering a number of generalizations of the Georgi-Glashow model. We study two different types of finite energy, regular configurations: solutions with net magnetic charge and monopole-antimonopole pairs with zero net magnetic charge. These configurations are endowed with an electric charge and carry also a nonvanishing angular momentum density. However, we argue that the qualitative results found in the Georgi-Glashow model are generic and thus a magnetic monopole cannot spin as long as the matter fields feature the usual “monopole” asymptotic behaviour independently of the dynamics of the model. A study of the properties of the dyons and magnetic dipoles in some generalizations of the Georgi-Glashow model supplemented with higher order Skyrme-like terms in the gauge curvature and Higgs fields is given quantitatively
On the phase structure of commuting matrix models
Get PDFWe perform a systematic study of commutative SO(p) invariant matrix models with quadratic and quartic potentials in the large N limit. We find that the physics of these systems depends crucially on the number of matrices with a critical rôle played by p = 4. For p ≤ 4 the system undergoes a phase transition accompanied by a topology change transition. For p > 4 the system is always in the topologically trivial phase and the eigenvalue distribution is a Dirac delta function spherical shell. We verify our analytic work with Monte Carlo simulations
A quantum critical point from flavours on a compact space
Get PDFWe analyse a 2 + 1 dimensional defect field theory on a two sphere in an external magnetic field. The theory is holographically dual to probe D5-branes in global AdS_5 × S^5 background. At any finite magnetic field only the confined phase of the theory is realised. There is a first order quantum phase transition, within the confined phase of theory, ending on a quantum critical point of a second order phase transition. We analyse the condensate and magnetisation of theory and construct its phase diagram. We study the critical exponents near the quantum critical point and find that the second derivatives of the free energy, with respect to the bare mass and the magnetic field, diverge with a critical exponent of −2/3. Next, we analyse the meson spectrum of the theory and identify a massless mode at the critical point signalling a diverging correlation length of the quantum fluctuations. We find that the derivative of the meson mass with respect to the bare mass also diverges with a critical exponent of −2/3. Finally, our studies of the magnetisation uncover a persistent diamagnetic response similar to that in mesoscopic systems, such as quantum dots and nano tubes
Gaussian decay for a difference of traces of the Schrödinger semigroup associated to the isotropic harmonic oscillator
Get PDFThis paper deals with the derivation of a sharp estimate on the difference of traces of the one-parameter Schrödinger semigroup associated to the quantum isotropic harmonic oscillator. Denoting by H_∞,κ the self-adjoint realization in L 2 (R d ), d ∈ {1, 2, 3} of the Schrödinger operator −(1/2)∆ + (1/2)κ^2*|x|^2, κ > 0 and by H_L,κ, L > 0 the Dirichlet realization in L^2(Λ^d_L) where Λ^d_L := {x ∈ R^d : −L/2 0 has a Gaussian decay in L for L sufficiently large. L The estimate we derive is sharp in the sense that its behavior when κ ↓ 0 and t ↓ 0 is similar to the one given by Tr_(L^2(R^d))*e^(−tH_∞,κ) = (2sinh((κ/2)*t))^(−d). Further, we give a simple application within the framework of quantum statistical mechanics
Properties of subentropy
Get PDFSubentropy is an entropy-like quantity that arises in quantum information theory; for example, it provides a tight lower bound on the accessible information for pure state ensembles, dual to the von Neumann entropy upper bound in Holevo’s theorem. Here we establish a series of properties of subentropy, paralleling the well-developed analogous theory for von Neumann entropy. Further, we show that subentropy is a lower bound for min-entropy. We introduce a notion of conditional subentropy and show that it can be used to provide an upper bound for the guessing probability of any classical-quantum state of two qubits; we conjecture that the bound applies also in higher dimensions. Finally we give an operational interpretation of subentropy within classical information theory
Dynamics of Non-supersymmetric Flavours
Get PDFWe continue investigating the effect of the back-reaction by non-supersymmetric probes in the Kuperstein-Sonnenschein model. In the limit where the back-reaction is small, we discuss physical properties of the back-reacted geometry. We further introduce additional probe flavours in this back-reacted geometry and study in detail the phase structure of this sector when a constant electromagnetic field or a chemical potential are present. We find that the Landau pole, which serves as the UV cut-off of the background geometry, also serves as an important scale in the corresponding thermodynamics of the additional flavour sector. We note that since these additional probe flavours are indistinguishable from the back-reacting flavours, the results we obtain point to a much richer phase structure of the system
Supersymmetric hidden sectors for heterotic standard models
Get PDFWithin the context of the weakly coupled E_8 × E_8 heterotic string, we study the hidden sector of heterotic standard model compactifications to four-dimensions. Specifically, we present a class of hidden sector vector bundles— composed of the direct sum of line bundles only—that, together with an effective bulk five-brane, renders the heterotic standard model entirely N = 1 supersymmetric. Two explicit hidden sectors are constructed and analyzed in this context; one with the gauge group E_7 × U(1) arising from a single line bundle and a second with an SO(12) × U(1) × U_(1) gauge group constructed from the direct sum of two line bundles. Each hidden sector bundle is shown to satisfy all requisite physical constraints within a finite region of the Kähler cone. We also clarify that the first Chern class of the line bundles need not be even in our context, as has often been imposed in the model building literature
Multi-matrix models at general coupling
Get PDFThe eigenvalue distribution of Hoppe’s two matrix model is investigated in detail as a function of the model’s coupling. For small couplings it is a perturbed Wigner semicircle, while for large couplings it is a parabolic distribution which crosses over to a Wigner semicircle for eigenvalues within approximately an inverse coupling from the boundary of the distribution. The model is approximately commuting at large couplings and we find the joint eigenvalue distribution of the two matrices. We also study a related three matrix model finding the corresponding three dimensional eigenvalue distribution there also. The techniques developed here are more widely applicable to other multi-matrix models