# High Energy Physics – Theory

curated by isomorphisms

### Exact meron Black Holes in four dimensional SU(2) Einstein-Yang-Mills theory.

In this paper an intrinsically non-Abelian black hole solution for the SU(2) Einstein-Yang-Mills theory in four dimensions is constructed. The gauge field of this solution has the form of a meron whereas the metric is the one of a Reissner-Nordström black hole in which, however, the coefficient of the $\large \dpi{100} \bg_white 1/r^2$ term is not an integration constant. Even if the stress-energy tensor of the Yang-Mills field is spherically symmetric, the field strength of the Yang-Mills field itself is not. A remarkable consequence of this fact, which allows to distinguish the present solution from essentially Abelian configurations, is the Jackiw, Rebbi, Hasenfratz, ‘t Hooft mechanism according to which excitations of bosonic fields moving in the background of a gauge field with this characteristic behave as Fermionic degrees of freedom.

1 year ago - 2

### Landau meets Newton: time translation symmetry breaking in classical mechanics.

Authors: Liu Zhao, Wei Xu, Pengfei Yu

Every classical Newtonian mechanical system can be equipped with a nonstandard Hamiltonian structure, in which the Hamiltonian is the square of the canonical Hamiltonian up to a constant shift, and the Poisson bracket is nonlinear. In such a formalism, time translation symmetry can be spontaneously broken, provided the potential function becomes negative. A nice analogy between time translation symmetry breaking and the Landau theory of second order phase transitions is established, together with several example cases illustrating time translation breaking ground states. In particular, the $\large \dpi{100} \bg_white \Lambda$CDM model of FRW cosmology is reformulated as the time translation symmetry breaking ground states.

1 year ago

### Partition Functions for Maxwell Theory on the Five-torus and for the Fivebrane on S^1XT^5.

Authors: Louise Dolan, Yang Sun

We compute the partition function of five-dimensional abelian gauge theory on a five-torus T5 with a general flat metric using the Dirac method of quantizing with constraints. We compare this with the partition function of a single fivebrane compactified on S1 times T5, which is obtained from the six-torus calculation of Dolan and Nappi. The radius R1 of the circle S1 is set to the dimensionful gauge coupling constant g^2= R1.

1 year ago

### Back-reaction of Non-supersymmetric Probes: Phase Transition and Stability.

Authors: Matthias Ihl (Dublin Inst.), Arnab Kundu (Texas U.), Sandipan Kundu (Texas U., TCC and Texas U.)

We consider back-reaction by non-supersymmetric D7/anti-D7 probe branes in the Kuperstein-Sonnenschein model at finite temperature. Using the smearing technique, we obtain an analytical solution for the back-reacted background to leading order in N_f/N_c. This back-reaction explicitly breaks the conformal invariance and introduces a dimension 6 operator in the dual field theory which is an irrelevant deformation of the original conformal field theory. We further probe this back-reacted background by introducing an additional set of probe brane/anti-brane. This additional probe sector undergoes a chiral phase transition at finite temperature, which is absent when the back-reaction vanishes. We investigate the corresponding phase diagram and the thermodynamics associated with this phase transition. We also argue that additional probes do not suffer from any instability caused by the back-reaction, which suggests that this system is stable beyond the probe limit.

1 year ago

### On Large N Solution of N=3 Chern-Simons-adjoint Theories.

Authors: Takao Suyama

The planar resolvent for N=3 U(N)_k Chern-Simons theory coupled to an arbitrary number of adjoint matters is determined. Analytic continuation of the ‘t Hooft coupling t is analyzed. The eigenvalue distribution turns out to be confined in a finite region even for a large t. The vev of a Wilson loop does not exhibit an exponential growth although such a behavior would be expected for theories with classical gravity duals.

1 year ago

### The O(4) violating terms of the multi-Higgs-doublet model potential cannot be excluded by imposing a symmetry on the Lagrangian.

Authors: M. Aa. Solberg

We prove there is no symmetry which, imposed on the general charge conjugation (C) invariant multi-Higgs-doublet model (NHDM), excludes exactly the O(4) violating terms from the potential. This is in part done by determining the exact subsymmetries of the custodial SO(4) symmetry of the standard model (SM) scalar Lagrangian. Furthermore, the Higgs family symmetries of the quadratic part of the general C invariant NHDM potential will also be symmetries of the O(4) violating terms of the potential, and hence cannot be applied to remove the O(4) violating terms from the potential. Finally, negative determinant elements of O(4) cannot be applied to expel the O(4) breaking terms from the NHDM potential either: We show there is no symmetries of the kinetic Higgs terms in the negative determinant part of O(4). This is also the case in the limit g’ -&gt; 0. Hence the custodial SO(4) symmetry is the largest symmetry group of the scalar sector of the SM in the limit g’ -&gt; 0.

1 year ago

### Higher Order Dilaton Interactions in the Nearly Conformal Limit of the Standard Model.

We investigate the Standard Model in the nearly conformal limit, in which conformal symmetry is broken only by the dilatation anomaly, through a hierarchy of anomalous Ward identities for the divergence of its dilatation current. In this approximation, the identities allow to extract the coupling of the dilaton to the trace anomaly, which we compute up to the quartic order in the conformal breaking scale. Our approach can be easily extended to discuss the anomaly contributions to the dilaton effective action to an arbitrarily high order. They allow to make a distinction between the Higgs and a dilaton at a phenomenological level.

1 year ago

### Production of Prompt Photons: Holographic Duality and Thermalization.

We study the production of prompt photons in strongly coupled out-of-equilibrium Super Yang-Mills plasma using the AdS/CFT correspondence. Our goal is to determine the photon emission spectrum at different stages of a thermalization process, which is modeled via the gravitational collapse of a thin spherical shell in AdS$\large \dpi{100} \bg_white _5$ space. Particular emphasis is placed on the limit of large frequencies, which we are able to treat analytically.

1 year ago

### D3/D7 Quark-Gluon Plasma with Magnetically Induced Anisotropy.

We study the effects of the temperature and of a magnetic field in the setup of an intersection of D3/D7 branes, where a large number of D7 branes is smeared in the transverse directions to allow for a perturbative solution in a backreaction parameter. The magnetic field sources an anisotropy in the plasma, and we investigate its physical consequences for the thermodynamics and energy loss of particles probing the system. In particular we comment on the stress-energy tensor of the plasma, the propagation of sound in the directions parallel and orthogonal to the magnetic field, the drag force of a quark moving through the medium and jet quenching.

1 year ago

### On a Recent Construction of "Vacuum-like" Quantum Field States in Curved Spacetime.

Authors: Christopher J. Fewster, Rainer Verch

Afshordi, Aslanbeigi and Sorkin have recently proposed a construction of a distinguished “S-J state” for scalar field theory in (bounded regions of) general curved spacetimes. We establish rigorously that the proposal is well-defined on globally hyperbolic spacetimes or spacetime regions that can be embedded as relatively compact subsets of other globally hyperbolic spacetimes, and also show that, whenever the proposal is well-defined, it yields a pure quasifree state. However, by explicitly considering portions of ultrastatic spacetimes, we show that the S-J state is not in general a Hadamard state. In the specific case where the Cauchy surface is a round 3-sphere, we prove that the representation induced by the S-J state is generally not unitarily equivalent to that of a Hadamard state, and indeed that the representations induced by S-J states on nested regions of the ultrastatic spacetime also fail to be unitarily equivalent in general. The implications of these results are discussed.

1 year ago