1,479 research outputs found
The mass of the b-quark from lattice NRQCD and lattice perturbation theory
We present a determination of the b-quark mass accurate through O(\alpha_s^2)
in perturbation theory and including partial contributions at O(\alpha_s^3).
Nonperturbative input comes from the calculation of the Upsilon and B_s
energies in lattice QCD including the effect of u, d and s sea quarks. We use
an improved NRQCD action for the b-quark. This is combined with the heavy quark
energy shift in NRQCD determined using a mixed approach of high-beta simulation
and automated lattice perturbation theory. Comparison with experiment enables
the quark mass to be extracted: in the MS bar scheme we find m_b(m_b) =
4.166(43) GeV.Comment: v2 - corrected some typos and an error in the summary plo
Trust economics feasibility study
We believe that enterprises and other organisations currently lack sophisticated methods and tools to determine if and how IT changes should be introduced in an organisation, such that objective, measurable goals are met. This is especially true when dealing with security-related IT decisions. We report on a feasibility study, Trust Economics, conducted to demonstrate that such methodology can be developed. Assuming a deep understanding of the IT involved, the main components of our trust economics approach are: (i) assess the economic or financial impact of IT security solutions; (ii) determine how humans interact with or respond to IT security solutions; (iii) based on above, use probabilistic and stochastic modelling tools to analyse the consequences of IT security decisions. In the feasibility study we apply the trust economics methodology to address how enterprises should protect themselves against accidental or malicious misuse of USB memory sticks, an acute problem in many industries
B-Meson Decay Constants from Improved Lattice Nonrelativistic QCD with Physical u,d,s, and c Quarks
We present the first lattice QCD calculation of the decay constants f(B) and f(Bs) with physical light quark masses. We use configurations generated by the MILC Collaboration including the effect of u, d, s, and c highly improved staggered quarks in the sea at three lattice spacings and with three u/d quark mass values going down to the physical value. We use improved nonrelativistic QCD (NRQCD) for the valence b quarks. Our results are f(B) = 0.186(4) GeV, f(Bs) = 0.224(4) GeV, f(Bs) / f(B) = 1.205(7), and M-Bs - M-B = 85(2) MeV, superseding earlier results with NRQCD b quarks. We discuss the implications of our results for the standard model rates for B-(s) -\u3emu(+)mu(-) and B -\u3etau n
TCT-27 Impact of Primary Stenting Compared to Balloon Dilatation Alone on Pulmonary Vein Restenosis
The weak password problem: chaos, criticality, and encrypted p-CAPTCHAs
Vulnerabilities related to weak passwords are a pressing global economic and
security issue. We report a novel, simple, and effective approach to address
the weak password problem. Building upon chaotic dynamics, criticality at phase
transitions, CAPTCHA recognition, and computational round-off errors we design
an algorithm that strengthens security of passwords. The core idea of our
method is to split a long and secure password into two components. The first
component is memorized by the user. The second component is transformed into a
CAPTCHA image and then protected using evolution of a two-dimensional dynamical
system close to a phase transition, in such a way that standard brute-force
attacks become ineffective. We expect our approach to have wide applications
for authentication and encryption technologies.Comment: 5 pages, 6 figer
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