15,194,480 research outputs found
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
Study of CP violation in Dalitz-plot analyses of B0 --> K+K-KS, B+ --> K+K-K+, and B+ --> KSKSK+
We perform amplitude analyses of the decays , , and , and measure CP-violating
parameters and partial branching fractions. The results are based on a data
sample of approximately decays, collected with the
BABAR detector at the PEP-II asymmetric-energy factory at the SLAC National
Accelerator Laboratory. For , we find a direct CP asymmetry
in of , which differs
from zero by . For , we measure the
CP-violating phase .
For , we measure an overall direct CP asymmetry of
. We also perform an angular-moment analysis of
the three channels, and determine that the state can be described
well by the sum of the resonances , , and
.Comment: 35 pages, 68 postscript figures. v3 - minor modifications to agree
with published versio
Afterglow upper limits for four short duration, hard spectrum gamma-ray bursts
We present interplanetary network localization, spectral, and time history
information for four short-duration, hard spectrum gamma-ray bursts, GRB000607,
001025B, 001204, and 010119. All of these events were followed up with
sensitive radio and optical observations (the first and only such bursts to be
followed up in the radio to date), but no detections were made, demonstrating
that the short bursts do not have anomalously intense afterglows. We discuss
the upper limits, and show that the lack of observable counterparts is
consistent both with the hypothesis that the afterglow behavior of the short
bursts is like that of the long duration bursts, many of which similarly have
no detectable afterglows, as well as with the hypothesis that the short bursts
have no detectable afterglows at all. Small number statistics do not allow a
clear choice between these alternatives, but given the present detection rates
of various missions, we show that progress can be expected in the near future.Comment: 19 pages, 4 figures; Revised version, accepted by the Astrophysical
Journa
The 1998 outburst of the X-ray transient XTE J2012+381 as observed with BeppoSAX
We report on the results of a series of X-ray observations of the transient
black hole candidate XTE J2012+381 during the 1998 outburst performed with the
BeppoSAX satellite. The observed broad-band energy spectrum can be described
with the superposition of an absorbed disk black body, an iron line plus a high
energy component, modelled with either a power law or a Comptonisation tail.
The source showed pronounced spectral variability between our five
observations. While the soft component in the spectrum remained almost
unchanged throughout our campaign, we detected a hard spectral tail which
extended to 200 keV in the first two observations, but became barely detectable
up to 50 keV in the following two. A further re-hardening is observed in the
final observation. The transition from a hard to a soft and then back to a hard
state occurred around an unabsorbed 0.1-200 keV luminosity of 10^38 erg/s (at
10 kpc). This indicates that state transitions in XTE 2012+281 are probably not
driven only by mass accretion rate, but additional physical parameters must
play a role in the evolution of the outburst.Comment: Paper accepted for publication on A&A (macro included, 9 pages, 5
figures
Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya
Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization
The Darkside Awakens
The DarkSide program at LNGS aims to perform background-free WIMP searches using two phase liquid argon time projection chambers, with the ultimate goal of covering all parameters down to the so-called neutrino floor. One of the distinct features of the program is the use of underground argon with has a reduced content of the radioactive Ar-39 compared to atmospheric argon. The DarkSide Collaboration is currently operating the DarkSide-50 experiment, the first such WIMP detector using underground argon. Operations with underground argon indicate a suppression of Ar-39 by a factor (1.4 +/- 0.2) x 10(3) relative to atmospheric argon. The new results obtained with DarkSide-50 and the plans for the next steps of the DarkSide program, the 20 t fiducial mass DarkSide-20k detector and the 200 t fiducial Argo, are reviewed in this proceedings.71814th International Conference on Topics in Astroparticle and Underground Physics (TAUP)Sep 07-11, 2015Torino, ITAL
Inclusive search for supersymmetry using razor variables in pp collisions at root s=13 TeV
Peer reviewe
A Targeted Search For Point Sources Of Eeev Photons With The Pierre Auger Observatory
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Simultaneous measurements of air showers with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for EeV photon point sources. Several Galactic and extragalactic candidate objects are grouped in classes to reduce the statistical penalty of many trials from that of a blind search and are analyzed for a significant excess above the background expectation. The presented search does not find any evidence for photon emission at candidate sources, and combined p-values for every class are reported. Particle and energy flux upper limits are given for selected candidate sources. These limits significantly constrain predictions of EeV proton emission models from non-transient Galactic and nearby extragalactic sources, as illustrated for the particular case of the Galactic center region.8372Argentina-Comision Nacional de Energia AtomicaAgencia Nacional de Promocion Cientifica y Tecnologica (ANPCyT)Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET)Gobierno de la Provincia de MendozaMunicipalidad de MalargueNDM Holdings and Valle Las Lenas, in gratitude for their continuing cooperation over land accessAustralia-the Australian Research CouncilBrazilConselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Financiadora de Estudos e Projetos (FINEP)Fundacao de Amparo a Pesquisa do Estado de Rio de Janeiro (FAPERJ)Sao Paulo Research Foundation (FAPESP) [2010/07359-6, 1999/05404-3]Ministerio de Ciencia e Tecnologia (MCT)Czech Republic-Grant [MSMT CR LG15014, LO1305, LM2015038]Czech Science Foundation [14-17501S]FranceCentre de Calcul [IN2P3/CNRS]Centre National de la Recherche Scientifique (CNRS)Conseil Regional Ile-deFranceDepartement Physique Nucleaire et Corpusculaire [PNC-IN2P3/CNRS]Departement Sciences de l'Univers [SDU-INSU/CNRS]Institut Lagrange de Paris (ILP), Investissements d'Avenir Programme Grant [LABEX ANR-10-LABX-63, ANR-11-IDEX-0004-02]Germany-Bundesministerium fur Bildung und Forschung (BMBF)Deutsche Forschungsgemeinschaft (DFG)Finanzministerium Baden-WurttembergHelmholtz Alliance for Astroparticle Physics (HAP)Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF)Ministerium fur Innovation, Wissenschaft und Forschung des Landes NordrheinWestfalenMinisterium fur Wissenschaft, Forschung und Kunst des Landes Baden-WurttembergItaly-Istituto Nazionale di Fisica Nucleare (INFN)Istituto Nazionale di Astrofisica (INAF)Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR)CETEMPS Center of ExcellenceMinistero degli Affari Esteri (MAE)Mexico-Consejo Nacional de Ciencia y Tecnologia (CONACYT) [167733]Universidad Nacional Autonoma de Mexico (UNAM)PAPIIT DGAPAUNAMNetherlands-Ministerie van Onderwijs, Cultuur en WetenschapNederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)Stichting voor Fundamenteel Onderzoek der Materie (FOM)Poland-National Centre for Research and Development [ERA-NETASPERA/01/11, ERA-NET-ASPERA/02/11]National Science Centre [2013/08/M/ST9/00322, 2013/08/M/ST9/00728, HARMONIA 5-2013/10/M/ST9/00062]Portugal-Portuguese national fundsFEDER funds within Programa Operacional Factores de Competitividade through Fundacao para a Ciencia e a Tecnologia (COMPETE)Romania-Romanian Authority for Scientific Research ANCSCNDI-UEFISCDI [20/2012, 194/2012, PN 16 42 01 02]Slovenia-Slovenian Research AgencySpainComunidad de MadridFondo Europeo de Desarrollo Regional (FEDER) fundsMinisterio de Economia y CompetitividadXunta de GaliciaEuropean Community 7th Framework Program [FP7-PEOPLE-2012-IEF-328826]USA Department of Energy [DE-AC02-07CH11359, DE-FR02-04ER41300, DE-FG02-99ER41107, DE-SC0011689]National Science Foundation [0450696]Grainger FoundationMarie Curie-IRSES/EPLANETEuropean Particle Physics Latin American NetworkEuropean Union 7th Framework Program [PIRSES-2009-GA-246806]UNESCOConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP
Study of W boson production in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV
A measurement is presented of W-boson production in PbPb collisions carried
out at a nucleon-nucleon (NN) centre-of-mass energy sqrt(s[NN]) of 2.76 TeV at
the LHC using the CMS detector. In data corresponding to an integrated
luminosity of 7.3 inverse microbarns, the number of W to mu mu-neutrino decays
is extracted in the region of muon pseudorapidity abs(eta[mu])<2.1 and
transverse momentum pt[mu]>25 GeV. Yields of muons found per unit of
pseudorapidity correspond to (159 +/- 10 (stat.) +/- 12 (syst.)) 10E-8 W(plus)
and (154 +/- 10 (stat.) +/- 12 (syst.)) 10E-8 W(minus) bosons per minimum-bias
PbPb collision. The dependence of W production on the centrality of PbPb
collisions is consistent with a scaling of the yield by the number of
incoherent NN collisions. The yield of W bosons is also studied in a sample of
pp interactions at sqrt(s)= 2.76 TeV corresponding to an integrated luminosity
of 231 inverse nanobarns. The individual W(plus) and W(minus) yields in PbPb
and pp collisions are found to agree, once the neutron and proton content in Pb
nuclei is taken into account. Likewise, the difference observed in the
dependence of the positive and negative muon production on pseudorapidity is
consistent with next-to-leading order perturbative QCD calculations.Comment: Submitted to Physics Letters
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