443 research outputs found
Influences of root-induced soil suction and root geometry on slope stability: a centrifuge study
Meson masses in large Nf QCD from the Bethe-Salpeter equation
We solve the homogeneous Bethe-Salpeter (HBS) equation for the scalar,
pseudoscalar, vector, and axial-vector bound states of quark and anti-quark in
large Nf QCD with the improved ladder approximation in the Landau gauge. The
quark mass function in the HBS equation is obtained from the Schwinger-Dyson
(SD) equation in the same approximation for consistency with the chiral
symmetry. Amazingly, due to the fact that the two-loop running coupling of
large Nf QCD is explicitly written in terms of an analytic function, large Nf
QCD turns out to be the first example in which the SD equation can be solved in
the complex plane and hence the HBS equation directly in the time-like region.
We find that approaching the chiral phase transition point from the broken
phase, the scalar, vector, and axial-vector meson masses vanish to zero with
the same scaling behavior, all degenerate with the massless pseudoscalar meson.
This may suggest a new type of manifestation of the chiral symmetry restoration
in large Nf QCD.Comment: 33 pages, 16 figures. Typos are corrected. Minor corrections and
references are added. Version to appear in Phys. Rev.
Topped MAC with extra dimensions?
We perform the most attractive channel (MAC) analysis in the top mode
standard model with TeV-scale extra dimensions, where the standard model gauge
bosons and the third generation of quarks and leptons are put in D(=6,8,10,...)
dimensions. In such a model, bulk gauge couplings rapidly grow in the
ultraviolet region. In order to make the scenario viable, only the attractive
force of the top condensate should exceed the critical coupling, while other
channels such as the bottom and tau condensates should not. We then find that
the top condensate can be the MAC for D=8, whereas the tau condensation is
favored for D=6. The analysis for D=10 strongly depends on the regularization
scheme. We predict masses of the top (m_t) and the Higgs (m_H), m_t=172-175 GeV
and m_H=176-188 GeV for D=8, based on the renormalization group for the top
Yukawa and Higgs quartic couplings with the compositeness conditions at the
scale where the bulk top condenses. The Higgs boson in such a characteristic
mass range will be immediately discovered in H -> WW^(*)/ZZ^(*) once the LHC
starts.Comment: REVTEX4, 24 pages, 21 figures, to appear in PRD. The title is changed
in PRD. One reference added, typos correcte
Continuity of the Maximum-Entropy Inference
We study the inverse problem of inferring the state of a finite-level quantum
system from expected values of a fixed set of observables, by maximizing a
continuous ranking function. We have proved earlier that the maximum-entropy
inference can be a discontinuous map from the convex set of expected values to
the convex set of states because the image contains states of reduced support,
while this map restricts to a smooth parametrization of a Gibbsian family of
fully supported states. Here we prove for arbitrary ranking functions that the
inference is continuous up to boundary points. This follows from a continuity
condition in terms of the openness of the restricted linear map from states to
their expected values. The openness condition shows also that ranking functions
with a discontinuous inference are typical. Moreover it shows that the
inference is continuous in the restriction to any polytope which implies that a
discontinuity belongs to the quantum domain of non-commutative observables and
that a geodesic closure of a Gibbsian family equals the set of maximum-entropy
states. We discuss eight descriptions of the set of maximum-entropy states with
proofs of accuracy and an analysis of deviations.Comment: 34 pages, 1 figur
Measurement of the solar 8B neutrino rate with a liquid scintillator target and 3 MeV energy threshold in the Borexino detector
We report the measurement of electron neutrino elastic scattering from 8B
solar neutrinos with 3 MeV energy threshold by the Borexino detector in Gran
Sasso (Italy). The rate of solar neutrino-induced electron scattering events
above this energy in Borexino is 0.217 +- 0.038 (stat) +- 0.008 (syst) cpd/100
t, which corresponds to the equivalent unoscillated flux of (2.4 +- 0.4 (stat)
+- 0.1 (syst))x10^6 cm^-2 s^-1, in good agreement with measurements from SNO
and SuperKamiokaNDE. Assuming the 8B neutrino flux predicted by the high
metallicity Standard Solar Model, the average 8B neutrino survival probability
above 3 MeV is measured to be 0.29+-0.10. The survival probabilities for 7Be
and 8B neutrinos as measured by Borexino differ by 1.9 sigma. These results are
consistent with the prediction of the MSW-LMA solution of a transition in the
solar electron neutrino survival probability between the low energy
vacuum-driven and the high-energy matter-enhanced solar neutrino oscillation
regimes.Comment: 10 pages, 8 figures, 6 table
Pulse-Shape discrimination with the Counting Test Facility
Pulse shape discrimination (PSD) is one of the most distinctive features of
liquid scintillators. Since the introduction of the scintillation techniques in
the field of particle detection, many studies have been carried out to
characterize intrinsic properties of the most common liquid scintillator
mixtures in this respect. Several application methods and algorithms able to
achieve optimum discrimination performances have been developed. However, the
vast majority of these studies have been performed on samples of small
dimensions. The Counting Test Facility, prototype of the solar neutrino
experiment Borexino, as a 4 ton spherical scintillation detector immersed in
1000 tons of shielding water, represents a unique opportunity to extend the
small-sample PSD studies to a large-volume setup. Specifically, in this work we
consider two different liquid scintillation mixtures employed in CTF,
illustrating for both the PSD characterization results obtained either with the
processing of the scintillation waveform through the optimum Gatti's method, or
via a more conventional approach based on the charge content of the
scintillation tail. The outcomes of this study, while interesting per se, are
also of paramount importance in view of the expected Borexino detector
performances, where PSD will be an essential tool in the framework of the
background rejection strategy needed to achieve the required sensitivity to the
solar neutrino signals.Comment: 39 pages, 17 figures, submitted to Nucl. Instr. Meth.
Recommended from our members
Observation of Geo-Neutrinos
Geo-neutrinos, electron anti-neutrinos produced in beta decays of naturally
occurring radioactive isotopes in the Earth, are a unique direct probe of our
planet's interior. We report the first observation at more than 3 C.L.
of geo-neutrinos, performed with the Borexino detector at Laboratori Nazionali
del Gran Sasso. Anti-neutrinos are detected through the neutron inverse beta
decay reaction. With a 252.6 ton-yr fiducial exposure after all selection cuts,
we detected 9.9^{+4.1}_{-3.4}(^{+14.6}_{-8.2}) geo-neutrino events, with errors
corresponding to a 68.3%(99.73%) C.L. From the profile, the
statistical significance of the Borexino geo-neutrino observation corresponds
to a 99.997% C.L. Our measurement of the geo-neutrinos rate is
3.9^{+1.6}_{-1.3}(^{+5.8}_{-3.2}) events/(100ton-yr). This measurement rejects
the hypothesis of an active geo-reactor in the Earth's core with a power above
3 TW at 95% C.L. The observed prompt positron spectrum above 2.6 MeV is
compatible with that expected from european nuclear reactors (mean base line of
approximately 1000 km). Our measurement of reactor anti-neutrinos excludes the
non-oscillation hypothesis at 99.60% C.L.Comment: 8 pages, 4 figures, 3 table
Coronary artery disease, left ventricular hypertrophy and diastolic dysfunction are associated with stroke in patients affected by persistent non-valvular atrial fibrillation: a case-control study
Persistent non-valvular atrial fibrillation (NVAF) is associated with an increased risk of cardiovascular events such as stroke, and its rate is expected to rise because of the ageing population. The absolute rate of stroke depends on age and comorbidity. Risk stratification for stroke in patients with NVAF derives from populations enrolled in randomized clinical trials. However, participants in clinical trials are often not representative of the general population. Many stroke risk stratification scores have been used, but they do not include transthoracic echocardiogram (TTE), pulsate wave Doppler (PWD) and tissue Doppler imaging (TDI), simple and non- invasive diagnostic tools. The role of TTE, PWD and TDI findings has not been previously determined. Our study goal was to determine the association between TTE and PWD findings and stroke prevalence in a population of NVAF prone outpatients
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS
The chi_b(nP) quarkonium states are produced in proton-proton collisions at
the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS
detector. Using a data sample corresponding to an integrated luminosity of 4.4
fb^-1, these states are reconstructed through their radiative decays to
Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks
corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new
structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is
also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes.
This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table,
corrected author list, matches final version in Physical Review Letter
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