117181820
Pair-production and Three-body Decay of the Lighter Stop at the ILC in One-loop Order in the MSSM
We have been developing a program package called GRACE/SUSY-loop which automatically calculates the MSSM amplitudes in one-loop order. We present numerical results of calculations for pair-production and three-body decay of the lighter stop ($\widetilde{t}_1$) at the International Linear Collider (ILC) using GRACE/SUSY-loop. Since the distributions of missing transverse energy (MET) depend on mass spectrum of SUSY particles, we consider two scenarios on three-body decay of $\widetilde{t}_1$. In these scenarios, both QCD and EW corrections have positive sign for decay widths and cross sections.
117876117
Present Status of GRACE/SUSY-loop
GRACE/SUSY-loop is a program package for the automatic calculation of the MSSM amplitudes in one-loop order. We present features of GRACE/SUSY-loop, processes calculated using GRACE/SUSY-loop and an extension of the non-linear gauge formalism applied to GRACE/SUSY-loop.
17427337
SUSY23 V2.0 : an event generator for supersymmetric processes at e+e- colliders
Abstract S usy23 is a Monte Carlo package for generating supersymmetric (SUSY) processes at e + e − colliders. Twenty-three types of SUSY processes with 2 or 3 final state particles at tree level are included in version 2.0. S usy23 addresses event simulation requirements at e + e − colliders such as LEP. Matrix elements are generated by GRACE with the helicity amplitude method for processes involving massive fermions. The phase space integration of the matrix element gives the total and differential cross sections, then unweighted events are generated. Sparticle widths and decay branching ratios are calculated. Each final state particle may then decay according to these probabilities. Spin correlations are taken into account in the decays of sparticles. Corrections of initial state radiation (ISR) are implemented in two ways, one is based on the electron structure function formalism and the second uses the parton shower algorithm called QEDPS. Parton shower and hadronization of the final quarks are performed through an interface to JETSET.
121708358
Single Scalar Electron Production in Polarized e+e- Collisions
14998834
Automatic Computation of Cross Sections in HEP ∗ Status of GRACE System
For the study of reactions in High Energy Physics (HEP) automatic computation systems have been developed and are widely used nowadays. GRACE is one of such systems and it has achieved much success in analyzing experimental data. Since we deal with the cross section whose value can be given by calculating hundreds of Feynman diagrams, we manage the large scale calculation, so that effective symbolic manipulation, the treat of singularity in the numerical integration are required. The talk will describe the software design of GRACE system and computational techniques in the GRACE. High energy experimental physics has produced excellent results thanks to the progress of the detectors and the development of the high energy accelerators with high luminosity. Accordingly, the accurate theoretical computation is required to compare experimental results with theoretical predictions. On the other hand, as the beam energy becomes higher, there appear the physics processes with many final state particles. As a matter of course the number of relevant Feynman diagrams becomes huge. This means that Feynman amplitude calculation is practically impossible when one calculates cross sections by hands. Since the perturbative calculation in quantum field theory is well-defined, it can be realized as an automatic computation system. There appeared several systems, for instance, CompHEP 1) and FeynArt/FeynCalc 2) , in HEP and nowadays the automatic computation of Feynman amplitudes becomes common. We have developed an automatic computation system named GRACE. 3) In section 2, we describe the feature of GRACE system as a concrete example of such system. In section 3, several physical achievements by GRACE are briefly explained. In section 4, we discuss the techniques in GRACE from the view point of computing.
5722422
The automatic computation for SUSY processes
AbstractWe have constructed a system for the automatic computation of cross-sectionsfor the processesof the SUSY QED by the extension of the GRACE system includinga Majorana fermion. The system has also been applied to another model includingMajorana fermions, MSSM, by the deﬁnition of the model ﬁle. IntroductionIthas been widely believed that there exists a symmetry called supersymmetry (SUSY)between bosons and fermions at the uniﬁcation-energy scale. It, however, is a brokensymmetry at the electroweak-energy scale. The relic of SUSY is expected to remain asa rich spectrum of SUSY particles, partners of usual matter fermions, gauge bosons andHiggs scalars, named sfermions, gauginos and higgsinos, respectively [1, 2, 3].The neutral gauginos and higgsinos are Majorana fermions, which become the mixedstates called neutralinos. Since anti-particles of Majorana fermions are themselves, thereexists so-called ‘Majorana-ﬂip’, the transition between particle and anti-particle. This hasbeen the most important problem which we should solve when we realize the automaticsystem for computation of the SUSY processes.1
11481265
Reduced qKZ Equation and Correlation Functions of the XXZ Model
Correlation functions of the XXZ model in the massive and massless regimes are known to satisfy a system of linear equations. The main relations among them are the difference equations obtained from the qKZ equation by specializing the variables (λ1, . . . ,λ2n) as (λ1, . . . ,λn,λn+1, . . . ,λ1+1). We call it the reduced qKZ equation. In this article we construct a special family of solutions to this system. They can be written as linear combinations of products of two transcendental functions ,ω with coefficients being rational functions. We show that correlation functions of the XXZ model in the massive regime are given by these formulas with an appropriate choice of ,ω. We also present a conjectural formula in the massless regime.
126190293
Studies on Holonomic Quantum Fields. 1.
197508512
TRANSFORMATION GROUPS FOR SOLITON EQUATIONS. 6. KP HIERARCHIES OF ORTHOGONAL AND SYMPLECTIC TYPE
15923760
Hidden Grassmann structure in the XXZ model III: introducing the Matsubara direction
We address the problem of computing temperature correlation functions of the XXZ chain, within the approach developed in our previous works. In this paper we calculate the expected values of a fermionic basis of quasi-local operators, in the infinite volume limit while keeping the Matsubara (or Trotter) direction finite. The result is expressed in terms of two basic quantities: a ratio ρ(ζ) of transfer matrix eigenvalues and a nearest neighbour correlator ω(ζ, ξ). We explain that the latter is interpreted as the canonical second kind differential in the theory of deformed Abelian integrals.
119733514
Fermionic structure in the sine-Gordon model: Form factors and null-vectors
Abstract The form factor bootstrap in integrable quantum field theory allows one to capture local fields in terms of infinite sequences of Laurent polynomials called ‘towers’. For the sine-Gordon model, towers are systematically described by fermions introduced some time ago by Babelon, Bernard and Smirnov. Recently the authors developed a new method for evaluating one-point functions of descendant fields, using yet another fermions which act on the space of local fields. The goal of this paper is to establish that these two fermions are one and the same object. This opens up a way for answering the longstanding question about how to identify precisely towers and local fields.