328 research outputs found
Two-loop matching of the dipole operators for and
The order corrections to the Wilson coefficients of the dipole
operators () at the matching scale are a crucial ingredient
for a complete next- to-leading logarithmic calculation of the branching ratio
for . Given the phenomenological relevance and the fact that
this two-loop calculation has been done so far only by one group [1], we
present a detailed re-calculation using a different method. Our results are in
complete agreement with those in ref. [1].Comment: 24 pages, latex, 6 figures include
Virtual O(\a_s) corrections to the inclusive decay
We present in detail the calculation of the O(\a_s) virtual corrections to
the matrix element for b \to s \g. Besides the one-loop virtual corrections
of the electromagnetic and color dipole operators and , we include
the important two-loop contribution of the four-Fermi operator . By
applying the Mellin-Barnes representation to certain internal propagators, the
result of the two-loop diagrams is obtained analytically as an expansion in
. These results are then combined with existing O(\a_s)
Bremsstrahlung corrections in order to obtain the inclusive rate for B \to X_s
\g. The new contributions drastically reduce the large renormalization scale
dependence of the leading logarithmic result. Thus a very precise Standard
Model prediction for this inclusive process will become possible once also the
corrections to the Wilson coefficients are available.Comment: 29 pages, uses epsfig.sty, 12 postscript figures include
Деформационное упрочнение начально-изотропных металлов при деформировании по траекториям малой кривизны
На примере стали мартенситного класса исследованы закономерности деформационного
упрочнения при нагружении по траекториям, имеющим вид двухзвенных ломаных, которым
соответствуют траектории деформирования малой кривизны. Показано, что поверхность
нагружения, разделяющая области упругого и упругопластического деформирования, смещается
в направлении вектора, который соединяет центр поверхности нагружения и изображающую
точку на траектории нагружения, при этом не изменяется форма ее фронтальной
части. Зависимость величины смещения центра поверхности нагружения от
интенсивности накопленных пластических деформаций описывается кривой, инвариантной
к виду траектории нагружения.На прикладі сталі мартенситного класу досліджено закономірності деформаційного
зміцнення при навантаженні по траєкторіях, що мають вигляд
дволанкових ламаних, яким відповідають траєкторії деформування малої
кривини. Показано, що поверхня навантаження, яка розділяє області пружного
та пружнопластичного деформування, зміщується у напрямку вектора,
який з ’єднує центр поверхні навантаження та відображуючу точку на траєкторії
навантаження, при цьому форма фронтальної частини не змінюється.
Залежність величини зміщення центра поверхні навантаження від інтенсивності
накопичених пластичних деформацій описується кривою, яка є інваріантною
відносно траєкторії навантаження.By the example of martensitic steel we study
regularities of strain hardening under loading
along two-section broken lines corresponding
to slightly curved strain paths. It is shown that
the loading surface separating domains of elastic
and elastoplastic strains (yield surface) is
displaced in the direction of a vector connecting
the surface center with the loading trajectory
image point, while the shape of its frontal
part remains unchanged. The yield surface center
displacement versus the intensity of accumulated
plastic strains is described by a curve
invariant to the loading trajectory
“Dogged” Search of Fresh Nakhla Surfaces Reveals New Alteration Textures
Special Issue: 74th Annual Meeting of the Meteoritical Society, August 8-12, 2011, London, U.K.International audienceCarbonaceous chondrites are considered as amongst the most primitive Solar System samples available. One of their primitive characteristics is their enrichment in volatile elements.This includes hydrogen, which is present in hydrated and hydroxylated minerals. More precisely, the mineralogy is expected to be dominated by phyllosilicates in the case of CM chondrites, and by Montmorillonite type clays in the case of CI. Here, in order to characterize and quantify the abundance of lowtemperature minerals in carbonaceous chondrites, we performed thermogravimetric analysis of matrix fragments of Tagish Lake, Murchison and Orgueil
Global Search for New Physics with 2.0/fb at CDF
Data collected in Run II of the Fermilab Tevatron are searched for
indications of new electroweak-scale physics. Rather than focusing on
particular new physics scenarios, CDF data are analyzed for discrepancies with
the standard model prediction. A model-independent approach (Vista) considers
gross features of the data, and is sensitive to new large cross-section
physics. Further sensitivity to new physics is provided by two additional
algorithms: a Bump Hunter searches invariant mass distributions for "bumps"
that could indicate resonant production of new particles; and the Sleuth
procedure scans for data excesses at large summed transverse momentum. This
combined global search for new physics in 2.0/fb of ppbar collisions at
sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D
Rapid Communication
Observation of Orbitally Excited B_s Mesons
We report the first observation of two narrow resonances consistent with
states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar
collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the
Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed
as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+,
\bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1})
= 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let
Direct and indirect costs associated with stereotactic radiosurgery or open surgery for medial temporal lobe epilepsy: Results from the ROSE trial
Objective
To determine whether a less-invasive approach to surgery for medically refractory temporal lobe epilepsy is associated with lower health care costs and costs of lost productivity over time, compared to open surgery.
Methods
We compared direct medical costs and indirect productivity costs associated with treatment with stereotactic radiosurgery (SRS) or anterior temporal lobectomy (ATL) in the ROSE (Radiosurgery or Open Surgery for Epilepsy) trial. Health care use was abstracted from hospital bills, the study database, and diaries in which participants recorded health care use and time lost from work while seeking care. Costs of use were calculated using a Medicare costing approach used in a prior study of the costs of ATL. The power of many analyses was limited by the sample size and data skewing.
Results
Combined treatment and follow-up costs (in thousands of US dollars) did not differ between SRS (n = 20, mean = 79.0, 95% CI = 60.09-103.8). Indirect costs also did not differ. More ATL than SRS participants were free of consciousness-impairing seizures in each year of follow-up (all P < 0.05). Costs declined following ATL (P = 0.005). Costs tended to increase over the first 18 months following SRS (P = 0.17) and declined thereafter (P = 0.06). This mostly reflected hospitalizations for SRS-related adverse events in the second year of follow-up.
Significance
Lower initial costs of SRS for medial temporal lobe epilepsy were largely offset by hospitalization costs related to adverse events later in the course of follow-up. Future studies of less-invasive alternatives to ATL will need to assess adverse events and major costs systematically and prospectively to understand the economic implications of adopting these technologies
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