115 research outputs found
Reduced neutron spectroscopic factors when using potential geometries constrained by Hartree-Fock calculations
We carry out a systematic analysis of angular distribution measurements for
selected ground-state to ground-state (d,p) and (p,d) neutron transfer
reactions, including the calcium isotopes. We propose a consistent three-body
model reaction methodology in which we constrain the transferred-neutron bound
state and nucleon-target optical potential geometries using modern Hartree-Fock
calculations. Our deduced neutron spectroscopic factors are found to be
suppressed by ~30% relative to independent-particle shell-model values, from
40Ca through 49Ca. The other nuclei studied, ranging from B to Ti, show similar
average suppressions with respect to large-basis shell-model expectations. Our
results are consistent with deduced spectroscopic strengths for neutrons and
protons from intermediate energy nucleon knockout reactions, and for protons
from (e,e'p) reactions, on well-bound nuclei. PACS: 24.50.+g, 24.10.Eq,
25.40.-h, 25.45.-zComment: 13 pages, 2 figures, Submitted to Physical Review
QCD correction to gluino decay to in the MSSM
We calculate the complete next-to-leading order QCD corrections to the
three-body decay of gluino into top-pair associated with a lightest neutralino
in the minimal supersymmetric standard model. We obtain that the LO and NLO QCD
corrected decay widths of at the
benchmark point are and 0.1069 GeV respectively, and
the relative correction is -28.2%. We investigate the dependence of the QCD
correction to on and the
masses of gluino, scalar top quarks and the lightest neutralino around the
benchmark point, separately. We find that the NLO QCD corrections
suppress the LO decay width, and the absolute relative correction can exceed
30% in some parameter space. Therefore, the QCD corrections to the three-body
decay should be taken into account for
the precise experimental measurement at future colliders. Moreover, we study
the distributions of the top-pair invariant mass () and the
missing energy (), and find that the line shapes of the LO
distributions of and are not obviously distorted by
the NLO QCD corrections.Comment: 23 pages, 10 figure
Measurement of the Forward-Backward Asymmetry in the B -> K(*) mu+ mu- Decay and First Observation of the Bs -> phi mu+ mu- Decay
We reconstruct the rare decays , , and in a data sample
corresponding to collected in collisions at
by the CDF II detector at the Fermilab Tevatron
Collider. Using and decays we report the branching ratios. In addition, we report
the measurement of the differential branching ratio and the muon
forward-backward asymmetry in the and decay modes, and the
longitudinal polarization in the decay mode with respect to the squared
dimuon mass. These are consistent with the theoretical prediction from the
standard model, and most recent determinations from other experiments and of
comparable accuracy. We also report the first observation of the {\mathcal{B}}(B^0_s \to
\phi\mu^+\mu^-) = [1.44 \pm 0.33 \pm 0.46] \times 10^{-6}27 \pm 6B^0_s$ decay observed.Comment: 7 pages, 2 figures, 3 tables. Submitted to Phys. Rev. Let
Measurements of the properties of Lambda_c(2595), Lambda_c(2625), Sigma_c(2455), and Sigma_c(2520) baryons
We report measurements of the resonance properties of Lambda_c(2595)+ and
Lambda_c(2625)+ baryons in their decays to Lambda_c+ pi+ pi- as well as
Sigma_c(2455)++,0 and Sigma_c(2520)++,0 baryons in their decays to Lambda_c+
pi+/- final states. These measurements are performed using data corresponding
to 5.2/fb of integrated luminosity from ppbar collisions at sqrt(s) = 1.96 TeV,
collected with the CDF II detector at the Fermilab Tevatron. Exploiting the
largest available charmed baryon sample, we measure masses and decay widths
with uncertainties comparable to the world averages for Sigma_c states, and
significantly smaller uncertainties than the world averages for excited
Lambda_c+ states.Comment: added one reference and one table, changed order of figures, 17
pages, 15 figure
Search for a New Heavy Gauge Boson Wprime with Electron + missing ET Event Signature in ppbar collisions at sqrt(s)=1.96 TeV
We present a search for a new heavy charged vector boson decaying
to an electron-neutrino pair in collisions at a center-of-mass
energy of 1.96\unit{TeV}. The data were collected with the CDF II detector
and correspond to an integrated luminosity of 5.3\unit{fb}^{-1}. No
significant excess above the standard model expectation is observed and we set
upper limits on . Assuming standard
model couplings to fermions and the neutrino from the boson decay to
be light, we exclude a boson with mass less than
1.12\unit{TeV/}c^2 at the 95\unit{%} confidence level.Comment: 7 pages, 2 figures Submitted to PR
Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV
A search for new physics is presented based on an event signature of at least
three jets accompanied by large missing transverse momentum, using a data
sample corresponding to an integrated luminosity of 36 inverse picobarns
collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector
at the LHC. No excess of events is observed above the expected standard model
backgrounds, which are all estimated from the data. Exclusion limits are
presented for the constrained minimal supersymmetric extension of the standard
model. Cross section limits are also presented using simplified models with new
particles decaying to an undetected particle and one or two jets
Search for three-jet resonances in pp Collisions at √s=7 TeV
This article is published Open Access at sciencedirect.com. It is distributed under the terms of the Creative Commons Attribution License 3.0.-- et al.Results are reported from a search for the production of three-jet resonances in pp collisions at a center-of-mass energy √s=7 TeV. The study uses the data sample collected by the CMS experiment at the LHC in 2011, corresponding to an integrated luminosity of 5.0fb -1. Events with high jet multiplicity and a large scalar sum of jet transverse momenta are analyzed for the presence of resonances in the three-jet invariant mass spectrum. No evidence for a narrow resonance is found in the data, and limits are set on the cross section for gluino pair production in an R-parity-violating supersymmetry model, for gluino masses greater than 280 GeV. Assuming a branching fraction for gluino decay into three jets of 100%, gluino masses below 460 GeV are excluded at 95% confidence level. These results significantly extend the range of previous limits. © 2012 CERN.European Commission; Federal Ministry of Science, Research and Economy (Austria); ); Agency for Innovation by Science and Technology (Belgium); Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Brasil); Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro; Fundação de Amparo à Pesquisa do Estado de São Paulo; Ministry of Science and Technology of the People's Republic of China; National Natural Science Foundation of China; Colciencias (Colombia); Ministry of Science, Education and Sports of the Republic of Croatia; Research Promotion Foundation (Cyprus); Centre National de la Recherche Scientifique (France); Bundesministerium für Bildung und Forschung (Deutschland); Deutsche Forschungsgemeinschaft; General Secretariat of Research and Technology (Greece); Helsinki Institute of Physics; National Office for Research and Technology (Hungary); Institute for Research in Fundamental Sciences (Iran); Science Foundation Ireland; Istituto Nazionale di Fisica Nucleare (Italia); Compagnia di San Paolo (Italia); National Research Foundation of Korea; Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (México); Consejo Nacional de Ciencia y Tecnología (México); Secretaría de Educación Pública (México); Universidad Autónoma de San Luis Potosí; Ministry of Science and Innovation (New Zealand); Pakistan Atomic Energy Commission; National Science Center (Poland); Fundação para a Ciência e a Tecnologia (Portugal); Joint Institute for Nuclear Research (Russia); Russian Foundation for Basic Research; Ministry of Education, Science and Technological Development (Serbia); Ministerio de Ciencia e Innovación (España); Swiss National Science Foundation.Peer Reviewe
Measurement of the t-channel single top quark production cross section in pp collisions at √s =7 TeV
Peer reviewe
Search for heavy bottom-like quarks decaying to an electron or muon and jets in collisions at TeV
We report the most sensitive direct search for pair production of
fourth-generation bottom-like chiral quarks () each decaying promptly to
. We search for an excess of events with an electron or muon, at least five
jets (one indentified as due to a or quark) and an imbalance of
transverse momentum using data from collisions collected by the CDF
II detector at Fermilab with an integrated luminosity of 4.8 fb. We
observe events consistent with background expectation and calculate upper
limits on the pair production cross section ( fb for 375 GeV/) and exclude \gevcc at 95%
confidence level.Comment: For submission to PR
Nietzsches gelijk: Waarom wijsheid achteraf onbillijk is
A search is performed for a massive new vector-like quark T, with charge 2/3, that is pair produced together with its antiparticle in proton-proton collisions. The data were collected by the CMS experiment at the Large Hadron Collider in 2012 at sqrt(s) = 8 TeV and correspond to an integrated luminosity of 19.5 inverse femtobarns. The T quark is assumed to decay into three different final states, bW, tZ, and tH. The search is carried out using events with at least one isolated lepton. No deviations from standard model expectations are observed, and lower limits are set on the T quark mass at 95% confidence level. The lower limit lies between 687 and 782 GeV for all possible values of the branching fractions into the three different final states assuming strong production. These limits are the most stringent constraints to date on the existence of such a quark
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