Hadroproduction of W+W−bbˉW^+ W^- b \bar{b} at NLO accuracy matched with shower Monte Carlo programs

We present the computation of the differential cross section for the process $pp(\bar{p}) \to (W^+\,W^-\,b\,\bar{b} \to)\;e^+\,\nu_e\,\mu^-\,\bar{\nu}_\mu\,b\, \bar{b}+X$ at NLO QCD accuracy matched to Shower Monte Carlo (SMC) simulations using PowHel, on the basis of the interface between HELAC-NLO and POWHEG-BOX. We include all resonant and non-resonant contributions. This is achieved by fully taking into account the effect of off-shell t-quarks and off-shell W-bosons in the complex mass scheme. We also present a program called DECAYER that can be used to let the t-quarks present in the event files for $pp(\bar{p}) \to {t\,\bar{t}\,X}$ processes decay including both the finite width of the t-quarks and spin correlations. We present predictions for both the Tevatron and the LHC, with emphasis on differences emerging from three different $W^+\,W^-\,b\,\bar{b}$ hadroproduction computations: (i) full implementation of the $p\,p(\bar{p}) \to W^+\,W^-\,b\,\bar{b}$ process, (ii) generating on-shell t-quarks pushed off-shell with a Breit-Wigner finite width and decayed by DECAYER, and (iii) on-shell t-quark production followed by decay in the narrow width approximation, as described by the SMC.Comment: 40 pages, 26 figures; slightly expanded version matching the one published in JHE

ttˉbbˉt\bar{t}b\bar{b} hadroproduction with massive bottom quarks with PowHel

The associated production of top-antitop-bottom-antibottom quarks is a relevant irreducible background for Higgs boson analyses in the top-antitop-Higgs production channel, with Higgs decaying into a bottom-antibottom quark pair. We implement this process in the PowHel event generator, considering the bottom quarks as massive in all steps of the computation which involves hard-scattering matrix-elements in the 4-flavour number scheme combined with 4-flavour Parton Distribution Functions. Predictions with NLO QCD + Parton Shower accuracy, as obtained by PowHel + PYTHIA, are compared to those which resulted from a previous PowHel implementation with hard-scattering matrix-elements in the 5-flavour number scheme, considering as a baseline the example of a realistic analysis of top-antitop hadroproduction with additional $b$-jet activity, performed by the CMS collaboration at the Large Hadron Collider.Comment: 9 pages, 6 figure

Top-antitop pair hadroproduction in association with a heavy boson at the NLO QCD accuracy + Parton Shower

The PowHel framework allows to make predictions of total and differential cross-sections of multiparticle hadroproduction processes at both NLO QCD accuracy and NLO QCD matched to Parton Shower, on the basis of the interface between the POWHEG-BOX and HELAC-NLO codes. It has already been applied to study several processes involving a top-antitop pair in association with a third particle or hadronic jet. Our most recent predictions concern top-antitop-V hadroproduction (with V = W or Z), at both parton and hadron level, by considering different decay channels (hadronic and leptonic) of the heavy particles. In particular, we show the results of our phenomenological analyses under the same system of cuts also recently adopted by the CMS collaboration at LHC.Comment: 4 pages, 2 figures, Proceedings of TOP 2012 - 5th International Workshop on Top Quark Physics, September 16 - 21 2012, Winchester, U

Molecular modeling of sigma 1 and sigma 2 receptor ligands: pharmacophore development and comparison using discotech and bioactivity prediction comparison of ab initio and density functional comfa studies for spiro and other receptor ligands

The role of the biological receptor is currently being studied by researchers in medicine. Information about sigma receptors in particular can be gained by studying the ligands associated with each type, sigma 1 or sigma 2. Sigma 1 receptor ligands consist of drug candidates that often have psychiatric and neurological applications; sigma 2 receptor ligands consist of drug candidates that have been linked with cancer treatment among other applications. Molecular modeling of biological receptor ligands often encompasses pharmacophore development and Comparative Molecular Field Analysis (CoMFA). Pharmacophore models are developed to understand the unique features such as binding groups that make a ligand bioactive. CoMFA uses experimental data of molecules, considered to be a training set, to yield bioactivity prediction for those molecules; this is the internal validation piece. An external test set of molecules with known experimental data can then be used for validation of the CoMFA models. The resulting CoMFA models create contour maps which provide information about the sterics and electrostatics, resulting in the ability to apply this information during the design of new ligands. The new molecules can then be tested in the validated CoMFA models to yield bioactivity predictions. This study describes the development of pharmacophore and Comparative Molecular Field Analysis (CoMFA) models for sigma 1 and sigma 2 receptor ligands. Distance Comparisons (DISCOtech) in SYBYL-X 2.1 is used as a tool for the pharmacophore development. A pharmacophore is developed for each individual class of molecules and for the entire set of sigma 1 molecules and sigma 2 molecules analyzed during this study, respectively. All compounds are calculated in SPARTAN ’14 using ab initio and density functional calculation methods H F/6-31 G* and B3LY P/6-31 G* prior to model development. These calculations determine the geometry optimization and electrostatic charges for each molecule. CoM FA studies, utilizing SY BY L-X 2. 1, are performed for 41 sigma 1 receptor l igands using the radiol igand [ H 3] (+) pentazoci ne and for 31 sigma 2 receptor l igands using [ H 3] (+) DTG in the presence of pentazoci ne. The CoMFA models developed confirm that bioactivity prediction comparison is reliable for both H F/6-31 G* and B3LYP/6-31G* optimized geometries for both sigma 1 and sigma 2 ligands; this is verified via both internal and external validation methods. The CoMFA contour maps are utilized to design new sigma 1 and sigma 2 l igands; the newly designed l igands are predicted to be highly active according to the CoMFA models. This study also compares CoMFA models between the ab initio and density functional calculation levels for sigma 1 and sigma 2 ligands, respectively. The similarities and differences between sigma 1 and sigma 2 receptor l igands are also analyzed via the developed pharmacophore models and generated CoM FA contour maps

t tbar W and t tbar Z Hadroproduction at NLO accuracy in QCD with Parton Shower and Hadronization effects

We present theoretical predictions for the hadroproduction of t tbar W+, t tbar W- and t tbar Z at LHC as obtained by matching numerical computations at NLO accuracy in QCD with Shower Monte Carlo programs. The calculation is performed by PowHel, relying on the POWHEG-BOX framework, that allows for the matching between the fixed order computation, with input of matrix elements produced by the HELAC-NLO collection of event generators, and the Parton Shower evolution, followed by hadronization and hadron decays as described by PYTHIA and HERWIG. We focus on the dilepton and trilepton decay channels, studied recently by the CMS Collaboration.Comment: 21 pages 12 figure

Z0 - boson production in association with a top anti-top pair at NLO accuracy with parton shower effects

We present predictions for the production cross section of a Standard Model Z0-boson in association with a top-antitop pair at the next-to-leading order accuracy in QCD, matched with shower Monte Carlo programs to evolve the system down to the hadronization energy scale. We adopt a framework based on three well established numerical codes, namely the POWHEG-BOX, used for computing the cross section, HELAC-NLO, which generates all necessary input matrix elements, and finally a parton shower program, such as PYTHIA or HERWIG, which allows for including t-quark and Z0-boson decays at the leading order accuracy and generates shower emissions, hadronization and hadron decays.Comment: 10 pages, 5 figures; found and corrected a bug in the phenomenological analysis, just affecting Fig.4 - 5 that turn out to change slightly with respect to our previous version and the cross-section values after all cuts. Conclusions qualitatively unchange

Helac-nlo

Based on the OPP technique and the HELAC framework, HELAC-1LOOP is a program that is capable of numerically evaluating QCD virtual corrections to scattering amplitudes. A detailed presentation of the algorithm is given, along with instructions to run the code and benchmark results. The program is part of the HELAC-NLO framework that allows for a complete evaluation of QCD NLO corrections.Comment: minor text revisions, version to appear in Comput.Phys.Commu

Instrumentation for a Mars Entry Experiment

This paper is based on a preliminary design of an entry science package for a Voyager Mars entry and landing capsule. The introduction outlines the various conditions under which the instruments must operate and the range of anticipated measurement parameters. The following sections describe the technology survey, alternative measurement concepts considered, and the instruments selected for the entry science package. The last section is devoted to the complete subsystem operation, sequence of events, data handling, and the system of backup measurements

Potential indicator enzyme s at broccoli blanching tecnology

Blanching of vegetables before freezing has some advantages as well as a number of disadvantages. Process optimization involves measuring the rate of enzyme destruction, such that the blanching time is just long enough to destroy the indicator enzyme. Eventually, peroxidases were almost universally the enzymes of choice, as they are usually the most heat-stable enzymes found in vegetables and fruits, so by the time they are inactivated no other enzymes or micro-organisms remain. But there is no evidence that peroxidases are involved in deteriorative reactions in the food. The aim of this work was to improve blanching technology in Hungarian frozen food industry with special emphasis on broccoli treatment. Instead of peroxidases, lipoxygenases were chosen to determine the adequate blanching parameters. Usually, lipoxygenases accompany lipases, so lipase activity is measured, too. On the basis of model blanching experiments, the conclusion is that lipoxygenase could be used as indicator enzyme. Being less heat stable than peroxidase, this enzyme requires shorter heat treatment, hence its inactivation should result in minimum quality deterioration and economic loss