65 research outputs found
Platform as a service integration for scientific computing using DIRAC
Cada dĂa crece mĂĄis a demanda de recursos de computaciĂłn requirida polos investigadores,
capacidades de cĂĄlculo que coexisten co crecente volume de datos xerado actualmente. Estes
investigadores estĂĄn a demandar un servizo de ComputaciĂłn de Altas PrestaciĂłns (HPC) que
permita a execuciĂłn das suas simulaciĂłns dunha forma na que se deslocalicen os recursos para
poder acceder aos mĂĄximos posibles, facilitandoo coa forma o mĂĄis cĂłmoda e segura para eles.
Doutra banda, as universidades estĂĄn conectadas con centros de investigaciĂłn con redes que
pusuen unha velocidade e fiabilidade que posibilitan a execuciĂłn de traballos de cĂĄlculo
cientĂfico. As capacidades de computo existentes en universidades van dende aulas informĂĄticas
para usos docentes, laboratorios, etc., ata clusters de ordenadores pertencentes a grupos de
investigaciĂłn. Usando tecnoloxĂas grid e cloud estes recursos computacionais heteroxĂ©neos
poderĂan ser reutilizados polos investigadores para realizar simulaciĂłns, aportando unha maior
cantidade de cĂłmputo a xa existente e deslocalizando os recursos entre distintos lugares ao
redor do planeta. O obxectivo desta tese Ă© adaptar a contorna para computaciĂłn distribuĂda
DIRAC, desenvolvida para o proxecto LHCb do CERN, para o seu uso por varias comunidades de
usuarios baseado nas tecnoloxĂas cloud e big data. Esta contorna pusuirĂa repositorios de
software centralizados que permitan proveer o software necesario para que a través dos
entornos na nube se poidan executar as aplicaciĂłns dos investigadores en calquera parte do
planeta dunha forma escalable, permitindo aprobeitar tanto recursos dedicados como nondedicados.
Avaliando asĂ a execuciĂłn desta plataforma para a realizaciĂłn de cĂĄlculos cientĂficos.
Este traballo comezarĂĄ coa obtenciĂłn de requisitos, para pasar despois ao proceso de
integraciĂłn bĂĄsica. Posteriormente, optimizarase o uso do software cientifico empregado para as
contornas cloud, tratando de adaptalo aos entornos virtualizados. Para iso, serĂĄ necesario
realizar un estudo estadĂstico que sexa o mĂĄis prĂłximo posible aos entornos en producciĂłn para
poder determinar e crear as infraestructuras adaptadas evitando asĂ a perda de rendemento
dentro de recursos. O seguinte caso serĂa utilizar as tecnoloxĂas virtualizadas, adaptando as
arquitecturas creadas, para a creaciĂłn de sistemas que permitan o envĂo de traballos que
requiran de grandes cantidades de datos no eido do big data dunha forma distribuida
Cloud flexibility using DIRAC interware
Communities of different locations are running their computing jobs on dedicated infrastructures without the need to worry about software, hardware or even the site where their programs are going to be executed. Nevertheless, this usually implies that they are restricted to use certain types or versions of an Operating System because either their software needs an definite version of a system library or a specific platform is required by the collaboration to which they belong. On this scenario, if a data center wants to service software to incompatible communities, it has to split its physical resources among those communities. This splitting will inevitably lead to an underuse of resources because the data centers are bound to have periods where one or more of its subclusters are idle. It is, in this situation, where Cloud Computing provides the flexibility and reduction in computational cost that data centers are searching for. This paper describes a set of realistic tests that we ran on one of such implementations. The test comprise software from three different HEP communities (Auger, LHCb and QCD phenomelogists) and the Parsec Benchmark Suite running on one or more of three Linux flavors (SL5, Ubuntu 10.04 and Fedora 13). The implemented infrastructure has, at the cloud level, CloudStack that manages the virtual machines (VM) and the hosts on which they run, and, at the user level, the DIRAC framework along with a VM extension that will submit, monitorize and keep track of the user jobs and also requests CloudStack to start or stop the necessary VM's. In this infrastructure, the community software is distributed via the CernVM-FS, which has been proven to be a reliable and scalable software distribution system. With the resulting infrastructure, users are allowed to send their jobs transparently to the Data Center. The main purpose of this system is the creation of flexible cluster, multiplatform with an scalable method for software distribution for several VOs. Users from different communities do not need to care about the installation of the standard software that is available at the nodes, nor the operating system of the host machine, which is transparent to the userThis work was supported by projects FPA2007-66437- C02-01/02 assigned to UB and FPA2010-21885-C02- 01/02 and TIN 2010-17541 USC. FPA2007-66152-C02-01/02 and FPA2010-21816-C02-01/02, assigned to PICS
Measurement of forward Z â e+eâ production sâs=8 TeV
A measurement of the cross-section for Z-boson production in the forward region of pp collisions at 8 TeV centre-of-mass energy is presented. The measurement is based on a sample of Z â e+eâ decays reconstructed using the LHCb detector, corresponding to an integrated luminosity of 2.0 fbâ1. The acceptance is defined by the requirements 2.0 20 GeV for the pseudorapidities and transverse momenta of the leptons. Their invariant mass is required to lie in the range 60-120 GeV. The cross-section is determined to beS
Measurement of indirect CP asymmetries in D0 â KâK+ and D0 â ÏâÏ+ decays using semileptonic B decays
Time-dependent CP asymmetries in the decay rates of the singly Cabibbo-suppressed decays D0 â KâK+ and D0 â ÏâÏ+ are measured in pp collision data corresponding to an integrated luminosity of 3.0 fbâ1 collected by the LHCb experiment. The D0 mesons are produced in semileptonic b-hadron decays, where the charge of the accompanying muon is used to determine the initial state as D0 or DÂŻ0. The asymmetries in effective lifetimes between D0 and DÂŻ0 decays, which are sensitive to indirect CP violation, are determined to be
AÎ(KâK+)=(â0.134±0.077â0.026â0.034)%,AÎ(ÏâÏ+)=(â0.092±0.145â0.025â0.033)%,
where the first uncertainties are statistical and the second systematic. This result is in agreement with previous measurements and with the hypothesis of no indirect CP violation in D0 decays.S
Precise measurements of the properties of the B1(5721)0,+ and B *2(5747)0,+ states and observation of B+,0Ïâ,+ mass structures
Invariant mass distributions of B+Ïâ and B0Ï+ combinations are investigated in order to study excited B mesons. The analysis is based on a data sample corresponding to 3.0 fbâ1 of pp collision data, recorded by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. Precise measurements of the masses and widths of the B1(5721)0,+ and B2(5747)0,+ states are reported. Clear enhancements, particularly prominent at high pion transverse momentum, are seen over background in the mass range 5850-6000 MeV in both B+Ïâ and B0Ï+ combinations. The structures are consistent with the presence of four excited B mesons, labelled B J (5840)0,+ and B J (5960)0,+, whose masses and widths are obtained under different hypotheses for their quantum numbersS
Observation of the B0âÏ0Ï0 decay from an amplitude analysis of B0â(Ï+Ïâ)(Ï+Ïâ)decays
Protonâproton collision data recorded in 2011 and 2012 by the LHCb experiment, corresponding to an integrated luminosity of 3.0fbâ1, are analysed to search for the charmless B0âÏ0Ï0decay. More than 600 B0â(Ï+Ïâ)(Ï+Ïâ)signal decays are selected and used to perform an amplitude analysis, under the assumption of no CP violation in the decay, from which the B0âÏ0Ï0decay is observed for the first time with 7.1 standard deviations significance. The fraction of B0âÏ0Ï0decays yielding a longitudinally polarised final state is measured to be fL=0.745+0.048â0.058(stat) ±0.034(syst). The B0âÏ0Ï0branching fraction, using the B0âÏKâ(892)0decay as reference, is also reported as B(B0âÏ0Ï0)=(0.94±0.17(stat)±0.09(syst)±0.06(BF))Ă10â6S
Measurement of CP asymmetries and polarisation fractions in B0sâKâ0KÂŻâ0 decays
An angular analysis of the decay B0sâKâ0KÂŻâ0 is performed using pp collisions corresponding to an integrated luminosity of 1.0 fbâ1 collected by the LHCb experiment at a centre-of-mass energy sâ=7 TeV. A combined angular and mass analysis separates six helicity amplitudes and allows the measurement of the longitudinal polarisation fraction f L = 0.201 ± 0.057 (stat.) ± 0.040 (syst.) for the B0sâKâ(892)0KÂŻâ(892)0 decay. A large scalar contribution from the K â0(1430) and K â0(800) resonances is found, allowing the determination of additional CP asymmetries. Triple product and direct CP asymmetries are determined to be compatible with the Standard Model expectations. The branching fraction B(BsâKâ(892)0KÂŻâ(892)0) is measured to be (10.8 ± 2.1 (stat.) ± 1.4 (syst.) ± 0.6 (f d /f s )) Ă 10â6.S
Search for CP violation in D0âÏâÏ+Ï0 decays with the energy test
A search for time-integrated CPviolation in the Cabibbo-suppressed decay D0âÏâÏ+Ï0is performed using for the first time an unbinned model-independent technique known as the energy test. Using protonâproton collision data, corresponding to an integrated luminosity of 2.0fbâ1collected by the LHCbdetector at a centre-of-mass energy of âs=8TeV, the worldâs best sensitivity to CPviolation in this decay is obtained. The data are found to be consistent with the hypothesis of CPsymmetry with a p-value of (2.6 ±0.5)%S
Study of the kinematic dependences of Î 0b production in pp collisions and a measurement of the Î 0bâââÎ +c Ï â branching fraction
The kinematic dependences of the relative production rates, fÎ0b/fd, of Î 0b baryons and B 0 mesons are measured using Î 0bâââÎ +c Ï â and BÂŻ0 âD+Ïâ decays. The measurements use proton-proton collision data, corresponding to an integrated luminosity of 1 fbâ1 at a centre-of-mass energy of 7 TeV, recorded in the forward region with the LHCb experiment. The relative production rates are observed to depend on the transverse momentum, p T, and pseudorapidity, η, of the beauty hadron, in the studied kinematic region 1.5 < p T < 40 GeV/c and 2 < η < 5. Using a previous LHCb measurement of fÎ0b/fd in semileptonic decays, the branching fraction âŹ(Î 0bâââÎ +c Ï â) =â(4.30â±â0.03 +â0.12ââ0.11â±â0.26â±â0.21) Ă 10ââ3 is obtained, where the first uncertainty is statistical, the second is systematic, the third is from the previous LHCb measurement of fÎ0b/fd and the fourth is due to the b BÂŻ0 âD+Ïâ branching fraction. This is the most precise measurement of a Î 0b branching fraction to date.S
Study of the rare B0s and B0s decays into the Ï+ÏâÎŒ+ÎŒâfinal state
A search for the rare decays B0sâÏ+ÏâÎŒ+ÎŒâand B0âÏ+ÏâÎŒ+ÎŒâis performed in a data set corresponding to an integrated luminosity of 3.0fbâ1collected by the LHCb detector in protonâproton collisions at centre-of-mass energies of 7 and 8TeV. Decay candidates with pion pairs that have invariant mass in the range 0.5â1.3GeV/c2and with muon pairs that do not originate from a resonance are considered. The first observation of the decay B0sâÏ+ÏâÎŒ+ÎŒâand the first evidence of the decay B0âÏ+ÏâÎŒ+ÎŒâare obtained and the branching fractions, restricted to the dipion-mass range considered, are measured to be B(B0sâÏ+ÏâÎŒ+ÎŒâ) =(8.6 ±1.5(stat) ±0.7(syst) ±0.7 (norm)) Ă10â8and B(B0âÏ+ÏâÎŒ+ÎŒâ) =(2.11±0.51(stat)±0.15(syst)±0.16(norm))Ă10â8, where the third uncertainty is due to the branching fraction of the decay B0âJ/Ï(âÎŒ+ÎŒâ)Kâ(892)0(âK+Ïâ), used as a normalisation.S
- âŠ