Multiphotons and Photon-Jets

We discuss an extension of the Standard Model with a new vector-boson decaying predominantly into a multi-photon final state through intermediate light degrees of freedom. The model has a distinctive phase in which the photons are collimated. As such, they would fail the isolation requirements of standard multi-photon searches, but group naturally into a novel object, the photon-jet. Once defined, the photon-jet object facilitates more inclusive searches for similar phenomena. We present a concrete model, discuss photon-jets more generally, and outline some strategies that may prove useful when searching for such objects.Comment: 4 pages, 2 figure

Optimal control of stochastic systems with interrupted observations

AbstractAn optimal control problem is considered for a nonlinear stochastic system with an interrupted observation mechanism that is characterized in terms of a jump Markov process taking on the values 0 or 1. The state of the system is described by a diffusion process, but the observation has components modulated by the jump process. The admissible control laws are smooth functions of the observation. Using the calculus of variations, necessary conditions on optimal controls are derived. These conditions amount to solving a set of four coupled nonlinear partial differential equations. A numerical procedure for solving these equations is suggested and an example dealt with numerically

Measurement of the Total (p,Pi) Cross Sections Through Residual Activity

This work was supported by National Science Foundation Grant PHY 75-00289 and Indiana Universit

Classical Simulation of Quantum Fields II

We consider the classical time evolution of a real scalar field in 2 dimensional Minkowski space with a $\lambda \phi^4$ interaction. We compute the spatial and temporal two-point correlation functions and extract the renormalized mass of the interacting theory. We find our results are consistent with the one- and two-loop quantum computation. We also perform Monte Carlo simulations of the quantum theory and conclude that the classical scheme is able to produce more accurate results with a fraction of the CPU time.Comment: 16 pages, 8 figures, now matches published versio

Measurement of the Total (p,Pi) Cross Sections Through Residual Activity

This work was supported by National Science Foundation Grants PHY 76-84033A01, PHY 78-22774, and Indiana Universit

Transition Probability Matrix Methodology for Incremental Risk Charge

As part of Basel II's incremental risk charge (IRC) methodology, this paper summarizes our extensive investigations of constructing transition probability matrices (TPMs) for unsecuritized credit products in the trading book. The objective is to create monthly or quarterly TPMs with predefined sectors and ratings that are consistent with the bank's Basel PDs. Constructing a TPM is not a unique process. We highlight various aspects of three types of uncertainties embedded in different construction methods: 1) the available historical data and the bank's rating philosophy; 2) the merger of one-year Basel PD and the chosen Moody's TPMs; and 3) deriving a monthly or quarterly TPM when the generator matrix does not exist. Given the fact that TPMs and specifically their PDs are the most important parameters in IRC, it is our view that banks may need to make discretionary choices regarding their methodology, with uncertainties well understood and managed

The (p,xn) Reaction from Protons on Bismuth at Intermediate Energies

This work was supported by National Science Foundation Grant PHY 76-84033 and Indiana Universit

Protein-DNA charge transport: Redox activation of a DNA repair protein by guanine radical

DNA charge transport (CT) chemistry provides a route to carry out oxidative DNA damage from a distance in a reaction that is sensitive to DNA mismatches and lesions. Here, DNA-mediated CT also leads to oxidation of a DNA-bound base excision repair enzyme, MutY. DNA-bound Ru(III), generated through a flash/quench technique, is found to promote oxidation of the [4Fe-4S](2+) cluster of MutY to [4Fe-4S](3+) and its decomposition product [3Fe-4S](1+). Flash/quench experiments monitored by EPR spectroscopy reveal spectra with g = 2.08, 2.06, and 2.02, characteristic of the oxidized clusters. Transient absorption spectra of poly(dGC) and [Ru(phen)(2)dppz](3+) (dppz = dipyridophenazine), generated in situ, show an absorption characteristic of the guanine radical that is depleted in the presence of MutY with formation instead of a long-lived species with an absorption at 405 nm; we attribute this absorption also to formation of the oxidized [4Fe-4S](3+) and [3Fe4S](1+) clusters. In ruthenium-tethered DNA assemblies, oxidative damage to the 5'-G of a 5'-GG-3' doublet is generated from a distance but this irreversible damage is inhibited by MutY and instead EPR experiments reveal cluster oxidation. With ruthenium-tethered assemblies containing duplex versus single-stranded regions, MutY oxidation is found to be mediated by the DNA duplex, with guanine radical as an intermediate oxidant; guanine radical formation facilitates MutY oxidation. A model is proposed for the redox activation of DNA repair proteins through DNA CT, with guanine radicals, the first product under oxidative stress, in oxidizing the DNA-bound repair proteins, providing the signal to stimulate DNA repair

Measurement of Total (p,Pi) Cross Sections Through Residual Activity

This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit