282,871 research outputs found
Atmospheric Charged Ratio and Measurement of Muon Annual Modulation with a Liquid Scintillation Detector at Soudan
We report a measurement of muon annual modulation in a 12-liter liquid
scintillation detector with a live-time of more than 4 years at the Soudan
Underground Laboratory. Muon minimum ionization in the detector is identified
by its observed pulse shape and large energy deposition. The measured muon rate
in the detector is 28.692.09 muons per day with a modulation amplitude of
2.66 1.0\% and a phase at Jul 22 36.2 days. This annual modulation
is correlated with the variation of the effective atmospheric temperature in
the stratosphere. The correlation coefficient, , is determined to
be . This can be interpreted as a measurement of the
atmospheric charged kaon to pion (/) ratio of 0.094
for 7 TeV, consistent with the measurement from the MINOS far
detector. To further constrain the value of / ratio, a Geant4
simulation of the primary cosmic-ray protons with energy up to 100 TeV is
implemented to study the correlation of / ratio and the muon annual
modulation for muon energy greater than 0.5 TeV. We find out that a charged
/ ratio of 0.1598, greater than the upper bound (0.138) from this work
at the production point 30 km above the Earth surface in the stratosphere
cannot induce muon annual modulation at the depth of Soudan.Comment: 6 pages and 11 figure
Interacting Individuals Leading to Zipf's Law
We present a general approach to explain the Zipf's law of city distribution.
If the simplest interaction (pairwise) is assumed, individuals tend to form
cities in agreement with the well-known statisticsComment: 4 pages 2 figure
Effective-Field-Theory Approach to Top-Quark Production and Decay
We discuss new physics in top-quark interactions, using an effective field
theory approach. We consider top-quark decay, single top production, and
top-quark pair production. We identify 15 dimension-six operators that
contribute to these processes, and we compute the deviation from the Standard
Model induced by these operators. The results provide a systematic way of
searching for (or obtaining bounds on) physics beyond the Standard Model.Comment: 24 pages, 12 figures; references added, typos correcte
Constraints on θ_(13) from a three-flavor oscillation analysis of reactor antineutrinos at KamLAND
We present new constraints on the neutrino oscillation parameters Δm^2_(21), θ_(12), and θ_(13) from a three flavor
analysis of solar and KamLAND data. The KamLAND data set includes data acquired following a radiopurity upgrade and amounts to a total exposure of 3.49 x 10^(32) target-proton-year. Under the assumption of CPT invariance, a two-flavor analysis (θ_(13) = 0) of the KamLAND and solar data yields the best-fit values tan^2θ_(12) = 0.444^(+0.036)_(-0.030) and Δm^2_(21) = 7.50^(+0.19)_(-0.20) x 10^(-5) eV^2; a three-flavor analysis with θ13 as a free parameter yields the best-fit values tan^2θ_(12) = 0.452^(+0.035)_(-0.033), Δm^2_(21) = 7.50^(+0.19)_(-0.20) x 10^(-5) eV^2, and sin^2θ_(13) = 0.020^(+0.016)_(-0.016). This θ_(13) interval is consistent with other recent work combining the CHOOZ, atmospheric and long-baseline accelerator experiments. We also present a new global θ_(13) analysis, incorporating the CHOOZ, atmospheric, and accelerator data, which indicates sin^2θ_(13) = 0.009^(+0.013)-_(0.007). A nonzero value is suggested, but only at the 79% C.L
Measurement of the ^8B solar neutrino flux with the KamLAND liquid scintillator detector
We report a measurement of the neutrino-electron elastic scattering rate from ^8B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5-MeV analysis threshold is 1.49 ± 0.14(stat) ± 0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a ^8B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77 ± 0.26(stat) ± 0.32(syst) ×10^6 cm^(−2_s^(−1). The analysis threshold is driven by ^(208)Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic ^(11)Be. The measured rate is consistent with existing measurements and with standard solar model predictions which include matter-enhanced neutrino oscillation
Emergence of Cooperation and Organization in an Evolutionary Game
A binary game is introduced and analysed. N players have to choose one of the
two sides independently and those on the minority side win. Players uses a
finite set of ad hoc strategies to make their decision, based on the past
record. The analysing power is limited and can adapt when necessary.
Interesting cooperation and competition pattern of the society seem to arise
and to be responsive to the payoff function.Comment: 8 pages, 13 figure
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