122046903
SuperB evaluation of DIRAC Distributed Infrastructure
The SuperB asymmetric energy e+e− collider and detector to be built at the newly founded Nicola Cabibbo Lab will provide a uniquely sensitive probe of New Physics in the flavour sector of the Standard Model. SuperB distributed computing group performed a detailed evaluation of DIRAC Distributed Infrastructure for use in the SuperB experiment based on the two use cases: End User Analysis and Monte Carlo Production. Test aims to evaluate DIRAC capabilities to manage both gLite and OSG sites, File Catalog management, job and data management features in SuperB realistic use cases.
62691127
Computing for the next generation flavour factories
The next generation of Super Flavor Factories, like SuperB and SuperKEKB, present significant computing challenges. Extrapolating the BaBar and Belle experience to the SuperB nominal luminosity of 1036 cm−2s−1, we estimate that the data size collected after a few years of operation is 200 PB and the amount of CPU required to process them of the order of 2000 KHep-Spec06. Already in the current phase of detector design, the amount of simulated events needed for estimating the impact on very rare benchmark channels is huge and has required the development of new simulation tools and the deployment of a worldwide production distributed system. With the collider is in operation, very large data set have to be managed and new technologies with potential large impact on the computational models, like the many core CPUs, need to be effectively exploited. In addition SuperB, like the LHC experiments, will have to make use of distributed computing resources accessible via the Grid infrastructures while providing an efficient and reliable data access model to its final users. To explore the key issues, a dedicated R&D program has been launched and is now in progress. A description of the R&D goals and the status of ongoing activities is presented.
56414672
Computing at SuperB
Domenico Del Prete*, Fabrizio Bianchi, Vania Boccia, Vincenzo Ciaschini, Marco Corvo, Guglielmo De Nardo, Andrea Di Simone, Giacinto Donvito, Armando Fella, Paolo Franchini, Francesco Giacomini, Alberto Gianoli, Giuliano Laccetti, Stefano Longo, Steffen Luitz, Eleonora Luppi, Matteo Manzali, Leonardo Merola, Silvio Pardi, Alejandro Perez, Matteo Rama, Guido Russo, Bruno Santeramo, Roberto Stroili, Luca Tommasetti
110146913
SuperB Simulation Production System
The SuperB asymmetric e+e− collider and detector to be built at the newly founded Nicola Cabibbo Lab will provide a uniquely sensitive probe of New Physics in the flavor sector of the Standard Model. Studying minute effects in the heavy quark and heavy lepton sectors requires a data sample of 75 ab−1 and a peak luminosity of 1036 cm−2 s−1. The SuperB Computing group is working on developing a simulation production framework capable to satisfy the experiment needs. It provides access to distributed resources in order to support both the detector design definition and its performance evaluation studies. During last year the framework has evolved from the point of view of job workflow, Grid services interfaces and technologies adoption. A complete code refactoring and sub-component language porting now permits the framework to sustain distributed production involving resources from two continents and Grid Flavors. In this paper we will report a complete description of the production system status of the art, its evolution and its integration with Grid services; in particular, we will focus on the utilization of new Grid component features as in LB and WMS version 3. Results from the last official SuperB production cycle will be reported.
62980375
ATLAS detector simulation: status and outlook
The simulation program for the ATLAS experiment at CERN is currently in a full operational mode and integrated into the ATLAS's common analysis framework, ATHENA. The OO approach, based on GEANT4, and in use during the DC2 data challenge has been interfaced within ATHENA and to GEANT4 using the LCG dictionaries and Python scripting. The robustness of the application was proved during the DC2 data challenge. The Python interface has added the flexibility, modularity and interactivity that the simulation tool needs to tackle, in a common way, different full ATLAS simulations setups, test beams and cosmic ray studies. Generation, simulation and digitization steps were exercised for performance and robustness tests. The comparison with real data has been possible in the context of the ATLAS combined test beam (2004) and ongoing cosmic ray studies
110445306
The distributed production system of the SuperB project: description and results
The SuperB experiment needs large samples of MonteCarlo simulated events in order to finalize the detector design and to estimate the data analysis performances. The requirements are beyond the capabilities of a single computing farm, so a distributed production model capable of exploiting the existing HEP worldwide distributed computing infrastructure is needed. In this paper we describe the set of tools that have been developed to manage the production of the required simulated events. The production of events follows three main phases: distribution of input data files to the remote site Storage Elements (SE); job submission, via SuperB GANGA interface, to all available remote sites; output files transfer to CNAF repository. The job workflow includes procedures for consistency checking, monitoring, data handling and bookkeeping. A replication mechanism allows storing the job output on the local site SE. Results from 2010 official productions are reported.
119185656
Conditional probabilities in the excursion set theory: generic barriers and non-Gaussian initial conditions
The excursion set theory, where density perturbations evolve stochastically with the smoothing scale, provides a method for computing the dark matter halo mass function. The computation of the mass function is mapped into the so-called first-passage time problem in the presence of a moving barrier. The excursion set theory is also a powerful formalism to study other properties of dark matter haloes such as halo bias, accretion rate, formation time, merging rate and the formation history of haloes. This is achieved by computing conditional probabilities with non-trivial initial conditions, and the conditional two-barrier first-crossing rate. In this paper we use the path integral formulation of the excursion set theory to calculate analytically these conditional probabilities in the presence of a generic moving barrier, including the one describing the ellipsoidal collapse, and for both Gaussian and non-Gaussian initial conditions. While most of our analysis associated with Gaussian initial conditions assumes Markovianity (top-hat in momentum space smoothing, rather than generic filters), the non-Markovianity of the random walks induced by non-Gaussianity is consistently accounted for. We compute, for a generic barrier, the first two scale-independent halo bias parameters, the conditional mass function and the halo formation time probability, including the effects of non-Gaussianities. We also provide the expression for the two-constant-barrier first-crossing rate when non-Markovian effects are induced by a top-hat filter function in real space.
119177589
Non-Gaussianities from the Standard Model Higgs
We have recently proposed that the Standard Model Higgs might be responsible for generating the cosmological perturbations of the universe by acting as an isocurvature mode during a de Sitter inflationary stage. In this paper we study the level of non-Gaussianity in the cosmological perturbations which are inevitably generated due to the non-linearities of the Standard Model Higgs potential. In particular, for the current central value of the top mass, we find that a future detection of non-Gaussianity would exclude the detection of tensor modes by the PLANCK satellite.
18711359
Quantum Boltzmann equations in resonant leptogenesis
The quantum Boltzmann equations relevant for leptogenesis, obtained using non-equilibrium quantum field theory, are described. They manifest memory effects leading to a time-dependent CP asymmetry which depends upon the previous history of the system. This result is particularly relevant in resonant leptogenesis where the asymmetry is generated by the decays of nearly mass-degenerate right-handed neutrinos. The impact of the non-trivial time evolution of the CP asymmetry is discussed either in the generic resonant leptogenesis scenario or in the more specific Minimal Lepton Flavour Violation framework. Significant quantitative differences arise with respect to the usual approach in which the time dependence of the CP asymmetry is neglected.
118597692
Electroweak lights from Dark Matter annihilations
The energy spectra of Standard Model particles originated from Dark Matter annihilations can be significantly altered by the inclusion of electroweak gauge boson radiation from the final state. A situation where this effect is particularly important is when a Majorana Dark Matter particle annihilates into two light fermions. This process is in p-wave and hence suppressed by the small value of the relative velocity of the annihilating particles. The inclusion of electroweak radiation eludes this suppression and opens up a potentially sizeable s-wave contribution to the annihilation cross section. I will discuss the impact of this effect on the fluxes of stable particles resulting from the Dark Matter annihilations, which are relevant for Dark Matter indirect searches.
12269508
On resonant leptogenesis
It has been recently shown that the quantum Boltzmann equations may be relevant for the leptogenesis scenario. In particular, they lead to a time-dependent CP asymmetry which depends upon the previous dynamics of the system. This memory effect in the CP asymmetry is particularly important in resonant leptogenesis where the asymmetry is generated by the decays of nearly mass-degenerate right-handed neutrinos. We study the impact of the nontrivial time evolution of the CP asymmetry in resonant leptogenesis, both in the one-flavour case and with flavour effects included. We show that significant qualitative and quantitative differences arise with respect to the case in which the time dependence of the CP asymmetry is neglected.