Hadronic Higgs Production and Decay in Supersymmetry at Next-to-Leading Order

Supersymmetric QCD corrections to the gluonic production and decay rate of a CP-even Higgs boson are evaluated at next-to-leading order. To this aim, we derive an effective Lagrangian for the gluon-Higgs coupling. We show that a consistent calculation requires the inclusion of gluino effects, in contrast to what has been done previously. The supersymmetric corrections to the gluon-Higgs coupling lead to a modification of the next-to-leading order K-factor for the Higgs production rate at the LHC by less than five percent.Comment: 13 pages, LaTeX, 12 ps-files included. v2: Typos fixed, references added, minor modifications. v3: Typos fixed

Non-equilibrium cluster-perturbation theory

The cluster perturbation theory (CPT) is one of the simplest but systematic quantum cluster approaches to lattice models of strongly correlated electrons with local interactions. By treating the inter-cluster potential, in addition to the interactions, as a perturbation, it is shown that the CPT can be reformulated as an all-order re-summation of diagrams within standard weak-coupling perturbation theory where vertex corrections are neglected. This reformulation is shown to allow for a straightforward generalization of the CPT to the general non-equilibrium case using contour-ordered Green's functions. Solving the resulting generalized CPT equation on the discretized Keldysh-Matsubara time contour, the transient dynamics of an essentially arbitrary initial pure or mixed state can be traced. In this way, the time-dependent expectation values of one-particle observables can be obtained within an approximation that neglects spatial correlations beyond the extension of the reference cluster. The necessary computational effort is very moderate. A detailed discussion and simple test calculations are presented to demonstrate the strengths and the shortcomings of the proposed approach. The non-equilibrium CPT is systematic and is controlled in principle by the inverse cluster size. It interpolates between the non-interacting and the atomic or decoupled-cluster limit which are recovered exactly and is found to predict the correct dynamics at very short times in a general non-trivial case. The effects of initial-state correlations on the subsequent dynamics and the necessity to extend the Keldysh contour by the imaginary Matsubara branch are analyzed carefully and demonstrated numerically. It is furthermore shown that the approach can describe the dissipation of spin and charge to an uncorrelated bath with an essentially arbitrary number of degrees of freedom.Comment: 14 pages, 9 figure

Psychological pressure in competitive environments: Evidence from a randomized natural experiment: Comment

Apesteguia and Palacios-Huerta (forthcoming) report for a sample of 129 shootouts from various seasons in ten different competitions that teams kicking first in soccer penalty shootouts win significantly more often than teams kicking second. Collecting data for the entire history of six major soccer competitions we cannot replicate their result. Teams kicking first win only 53.4% of 262 shootouts in our data, which is not significantly different from random. Our findings have two implications: (1) Apesteguia and Palacios-Huerta’s results are not generally robust. (2) Using specific subsamples without a coherent criterion for data selection might lead to non-representative findings

Reply to [arXiv:1201.5347] "Comment on 'Vortex-assisted photon counts and their magnetic field dependence in single-photon superconducting detectors'"

We argue that cutoff in the London model cannot be settled without use of the microscopic theory

A Shortcut to the Q-Operator

Baxter's Q-operator is generally believed to be the most powerful tool for the exact diagonalization of integrable models. Curiously, it has hitherto not yet been properly constructed in the simplest such system, the compact spin-1/2 Heisenberg-Bethe XXX spin chain. Here we attempt to fill this gap and show how two linearly independent operatorial solutions to Baxter's TQ equation may be constructed as commuting transfer matrices if a twist field is present. The latter are obtained by tracing over infinitely many oscillator states living in the auxiliary channel of an associated monodromy matrix. We furthermore compare and differentiate our approach to earlier articles addressing the problem of the construction of the Q-operator for the XXX chain. Finally we speculate on the importance of Q-operators for the physical interpretation of recent proposals for the Y-system of AdS/CFT.Comment: 41 pages, 2 figures; v2: references added; v3: version published in J. Stat. Mec