Comparison of phase space slicing and dipole subtraction methods for \gamma^* \rightarrow Q\bar{Q}

We compare the phase space slicing and dipole subtraction methods in the computation of the inclusive and differential next-to-leading order cross sections for heavy quark production in the simple process . For the phase space slicing method we study the effects of improvement terms that remove restrictions on the slicing parameter . For the dipole method our comparison is a first check on some of its counterterms involving massive quarks, derived recently. In our comparison we address issues such as numerical accuracy and efficiency. Received: 15 October 2001 / Published online: 25 January 2002     

Single top production in a non-minimal supersymmetric model

We study single top production at the LHC in a SUSY-QCD model with a heavy Dirac gluino. The presence of a heavy Dirac gluino allows for notable top-up flavour changing neutral currents. In this scenario, we find that the process ug→tg$ug\to tg$ gives the largest contribution to single top production via FCNCs at the LHC. The key features of this signal are that the top quark is produced very forward and that it is asymmetric to its anti-top counterpart, as the latter lacks a valence quark.     

Charged Higgs boson production in association with a top quark in MC@NLO

The European Physical Journal C - We discuss the calculation of charged Higgs boson production in association with a top quark in the MC@NLO framework for combining NLO matrix elements with a...     

Novel precursors of solvated electrons in water: evidence for a charge transfer process

Femtosecond midinfrared spectroscopy of water (heavy water) after two photon excitation at 9 eV provides clear evidence for two short-lived precursors of the hydrated electron preceding the well-known "wet electron." The measured first intermediate with peak absorption at 2.9 (4.1) microm is proposed to represent an O(H, D):e(-) complex. The subsequent solvation proceeds via e(-):[(H, D)2O](n) complexes at approximately 1.6 (2.0) microm in the electronic ground state, involving an increasing number of water molecules during the first 200 fs and followed by the wet electron.     

An Analytical Model of Porosity–Permeability for Porous and Fractured Media

The classic Kozeny–Carman equation (KC) uses parameters that are empirically based or not readily measureable for predicting the permeability of unfractured porous media. Numerous published KC modifications share this disadvantage, which potentially limits the range of conditions under which the equations are applicable. It is not straightforward to formulate non-empirical general approaches due to the challenges of representing complex pore and fracture networks. Fractal-based expressions are increasingly popular in this regard, but have not yet been applied accurately and without empirical constants to estimating rock permeability. This study introduces a general non-empirical analytical KC-type expression for predicting matrix and fracture permeability during single-phase flow. It uses fractal methods to characterize geometric factors such as pore connectivity, non-uniform grain or crystal size distribution, pore arrangement, and fracture distribution in relation to pore distribution. Advances include (i) modification of the fractal approach used by Yu and coworkers for industrial applications to formulate KC-type expressions that are consistent with pore size observations on rocks. (ii) Consideration of cross-flow between pores that adhere to a fractal size distribution. (iii) Extension of the classic KC equation to fractured media absent empirical constants, a particular contribution of the study. Predictions based on the novel expression correspond well to measured matrix and fracture permeability data from natural sandstone and carbonate rocks, although the currently available dataset for fractures is sparse. The correspondence between model calculation results and matrix data is better than for existing models.     

The precursors of the solvated electron in methanol studied by femtosecond pump-repump-probe spectroscopy

Using UV photoionization and delayed near-infrared reexcitation pulses, a novel time-, frequency-, and polarization-resolved pump-repump-probe spectroscopy is conducted in the probing range of 450-2400 nm with improved experimental accuracy. Both the generation process and relaxation dynamics following selective repumping of intermediate species of the solvated electron are investigated and analyzed self-consistently with the help of a kinetic model. New insight in the intermediates of the trapped electron is gained leading to a unique microscopic picture.     

Working group report: Quantum chromodynamics

This is the report of the QCD working sub-group at WHEPP-8 which was part of the QCD and QGP working group. Discussion and work on some aspects of resummation and parton distribution are reported.