18800497
LOOP EQUATIONS AND THE TOPOLOGICAL PHASE OF MULTI-CUT MATRIX MODELS
We study the double scaling limit of mKdV type, realized in the two-cut Hermitian matrix model. Building on the work of Periwal and Shevitz and of Nappi, we find an exact solution including all odd scaling operators, in terms of a hierarchy of flows of 2×2 matrices. We derive from it loop equations which can be expressed as Virasoro constraints on the partition function. We discover a “pure topological” phase of the theory in which all correlation functions are determined by recursion relations. We also examine macroscopic loop amplitudes, which suggest a relation to 2D gravity coupled to dense polymers.
15868022
Donaldson Invariants for Non-Simply Connected Manifolds
Abstract:We study Coulomb branch (“u-plane”) integrals for supersymmetric SU(2),SO(3) Yang–Mills theory on 4-manifolds X of b1(X)>0, b2+(X)= 1. Using wall-crossing arguments we derive expressions for the Donaldson invariants for manifolds with b1(X)>0, b2+(X)>0. Explicit expressions for , where Fg is a Riemann surface of genus g are obtained using Kronecker's double series identity. The result might be useful in future studies of quantum cohomology.
124306496
The M theory three form and E(8) gauge theory
14205277
Melvin Models and Diophantine Approximation
Melvin models with irrational twist parameter provide an interesting example of conformal field theories with non-compact target space, and localized states which are arbitrarily close to being delocalized. We study the torus partition sum of these models, focusing on the properties of the regularized dimension of the space of localized states. We show that its behavior is related to interesting arithmetic properties of the twist parameter γ, such as the Lyapunov exponent. Moreover, for γ in a set of measure one the regularized dimension is in fact not a well-defined number but must be considered as a random variable in a probability distribution.
122595912
Anomalies in Nonlinear $\sigma$ Models
Certain nonlinear sigma models with fermions suffer from an anomaly similar to the one in non-Abelian gauge theory. We exhibit this anomaly using both perturbative and global methods. The affected theories are ill defined and hence unsuitable for describing low-energy dynamics. They include certain supersymmetric models in four space-time dimensions.
118337669
Symmetries of the Bosonic String S-Matrix
The bracket operation on mutually local BRST classes may be combined with Lorentz invariance and analyticity to write an infinite set of finite difference relations on string scattering amplitudes. When combined with some simple physical criteria these relations uniquely determine the genus zero string $S$-matrix for $N\leq 26$-particle scattering in $\IR^{25,1}$ in terms of a single parameter, $\kappa$, the string coupling. We propose that the high-energy limit of the relations are the Ward identities for the high-energy symmetries of string theory.
41524496
SUPERSYMMETRIC ELECTROWEAK PHASE TRANSITION : BARYOGENESIS VERSUS EXPERIMENTAL CONSTRAINTS
We use the two loop effective potential to study the first order electroweak phase transition in the minimial supersymmetric standard model. A global search of the parameter space is made to identify parameters compatible with electroweak baryogenesis. We improve on previous such studies by fully incorporating squark and Higgs boson mixing, by using the latest experimental constraints, and by computing the latent heat and the sphaleron rate. We find the constraints tan beta > 2.1, top squark mass < 172 GeV, and Higgs mass < 107 GeV (becoming more or less restrictive if the heavy stop has mass less than or greater than 1 TeV). We also find that the change in tan beta in the bubble wall is rarely greater than 0.001, which severely constrains the mechanism of baryogenesis.
7244562
Electroweak bubble wall friction: analytic results
We present an entirely analytic, leading log order determination of the friction an electroweak bubble wall feels during a first order electroweak phase transition. The friction is dominated by W bosons, and gives a wall velocity parametrically ~ αw, and numerically small, ~ .01÷0.1 depending on the Higgs mass.
119208046
Composite magnetic dark matter and the 130 GeV line
We propose an economical model to explain the apparent 130 GeV gamma ray peak, found in the Fermi/LAT data, in terms of dark matter annihilation through a dipole moment interaction. The annihilating dark matter particles represent a subdominant component, with mass density 7-17% of the total DM density; and they only annihilate into gamma gamma, gamma Z, and ZZ, through a magnetic (or electric) dipole moment. Annihilation into other standard model particles is suppressed, due to a mass splitting in the magnetic dipole case, or to p-wave scattering in the electric dipole case. In either case, the observed signal requires a dipole moment of strength mu ~ 2/TeV. We argue that composite models are the preferred means of generating such a large dipole moment, and that the magnetic case is more natural than the electric one. We present a simple model involving a scalar and fermionic techniquark of a confining SU(2) gauge symmetry. We point out some generic challenges for getting such a model to work. The new physics leading to a sufficiently large dipole moment is below the TeV scale, indicating that the magnetic moment is not a valid effective operator for LHC physics, and that production of the strongly interacting constituents, followed by techni-hadronization, is a more likely signature than monophoton events. In particular, 4-photon events from the decays of bound state pairs are predicted.
116626711
UV cascade in classical Yang-Mills theory via kinetic theory
We show that classical Yang-Mills theory with statistically homogeneous and isotropic initial conditions has a kinetic description and approaches a scaling solution at late times. We find the scaling solution by explicitly solving the Boltzmann equations, including all dominant processes (elastic and number-changing). Above a scale ˜ pmax ∝ t 1 7 the occupancy falls exponentially in p. For asymptotically late times and sufficiently small momenta the occupancy scales as f(p) ∝ 1/p, but this behavior sets in only at very late time scales. We find quantitative agreement of our results with lattice simulations, for times and momenta within the range of validity of kinetic theory.
119099410
Energy loss of leading hadrons and direct photon production in evolving quark-gluon plasma
We calculate the nuclear modification factor of neutral pions and the photon yield at high p{sub T} in central Au-Au collisions at the Relativistic Heavy-Ion Collider (RHIC) ({radical}(s)=200 GeV) and Pb-Pb collisions at the Large Hadron Collider (LHC) ({radical}(s)=5500 GeV). A leading-order accurate treatment of jet energy loss in the medium has been convolved with a physical description of the initial spatial distribution of jets and a one dimensional hydrodynamic expansion. We reproduce the nuclear modification factor for pions R{sub AA} at RHIC, assuming an initial temperature T{sub i}=370 MeV and a formation time {tau}{sub i}=0.26 fm/c, corresponding to dN/dy=1260. The resulting suppression depends on the particle rapidity density dN/dy but weakly on the initial temperature. The jet energy loss treatment is also included in the calculation of high p{sub T} photons. Photons coming from primordial hard N-N scattering are the dominant contribution at RHIC for p{sub T}>5 GeV, whereas at the LHC, the range 8