21 research outputs found
Diffractive Dijet Production at sqrt(s)=630 and 1800 GeV at the Fermilab Tevatron
We report a measurement of the diffractive structure function of
the antiproton obtained from a study of dijet events produced in association
with a leading antiproton in collisions at GeV at the
Fermilab Tevatron. The ratio of at GeV to
obtained from a similar measurement at GeV is compared with
expectations from QCD factorization and with theoretical predictions. We also
report a measurement of the (-Pomeron) and ( of parton in
Pomeron) dependence of at GeV. In the region
, GeV and , is
found to be of the form , which obeys
- factorization.Comment: LaTeX, 9 pages, Submitted to Phys. Rev. Letter
A Study of B0 -> J/psi K(*)0 pi+ pi- Decays with the Collider Detector at Fermilab
We report a study of the decays B0 -> J/psi K(*)0 pi+ pi-, which involve the
creation of a u u-bar or d d-bar quark pair in addition to a b-bar -> c-bar(c
s-bar) decay. The data sample consists of 110 1/pb of p p-bar collisions at
sqrt{s} = 1.8 TeV collected by the CDF detector at the Fermilab Tevatron
collider during 1992-1995. We measure the branching ratios to be BR(B0 -> J/psi
K*0 pi+ pi-) = (8.0 +- 2.2 +- 1.5) * 10^{-4} and BR(B0 -> J/psi K0 pi+ pi-) =
(1.1 +- 0.4 +- 0.2) * 10^{-3}. Contributions to these decays are seen from
psi(2S) K(*)0, J/psi K0 rho0, J/psi K*+ pi-, and J/psi K1(1270)
Search for Single-Top-Quark Production in p-pbar Collisions at sqrt(s)=1.8 TeV
We search for standard model single-top-quark production in the W-gluon
fusion and W* channels using 106 pb^-1 of data from p-pbar collisions at
sqrt(s)=1.8 TeV collected with the Collider Detector at Fermilab. We set an
upper limit at 95% C.L. on the combined W-gluon fusion and W* single-top cross
section of 14 pb, roughly six times larger than the standard model prediction.
Separate 95% C.L. upper limits in the W-gluon fusion and W* channels are also
determined and are found to be 13 and 18 pb, respectively.Comment: 6 pages, 2 figures; submitted to Phys. Rev. Let
Measurement of the polar-angle distribution of leptons from W boson decay as a function of the W transverse momentum in proton-antiproton collisions at sqrt{s}=1.8 TeV
We present a measurement of the coefficient alpha_2 of the leptonic
polar-angle distribution from W boson decays, as a function of the W transverse
momentum. The measurement uses an 80+/-4 pb^{-1} sample of proton-antiproton
collisions at sqrt{s}=1.8 TeV collected by the CDF detector and includes data
from both the W->e+nu and W->mu+nu decay channels. We fit the W boson
transverse mass distribution to a set of templates from a Monte Carlo event
generator and detector simulation in several ranges of the W transverse
momentum. The measurement agrees with the Standard Model expectation, whereby
the ratio of longitudinally to transversely polarized W bosons, in the
Collins-Soper W rest frame, increases with the W transverse momentum at a rate
of approximately 15% per 10 GeV/c.Comment: 47 pages, 16 figures, submitted to Physical Review
Measurement of the Ratio of b Quark Production Cross Sections in Antiproton-Proton Collisions at 630 GeV and 1800 GeV
We report a measurement of the ratio of the bottom quark production cross
section in antiproton-proton collisions at 630 GeV to 1800 GeV using bottom
quarks with transverse momenta greater than 10.75 GeV identified through their
semileptonic decays and long lifetimes. The measured ratio
sigma(630)/sigma(1800) = 0.171 +/- .024 +/- .012 is in good agreement with
next-to-leading order (NLO) quantum chromodynamics (QCD)
Controls on explosive-effusive volcanic eruption styles
One of the biggest challenges in volcanic hazard assessment is to understand how and why eruptive style changes within the same eruptive period or even from one eruption to the next at a given volcano. This review evaluates the competing processes that lead to explosive and effusive eruptions of silicic magmas. Eruptive style depends on a set of feedbacks involving interrelated magmatic properties and processes. Foremost of these are magma viscosity, gas loss, and external properties such as conduit geometry. Ultimately, these parameters control the speed at which magmas ascend, decompress and outgas en route to the surface, and thus determine eruptive style and evolution
Inflamm-Aging
Inflammaging is a theory of aging based on the evidence that the evolutionary unpredicted persistent/increasing exposure to a variety of external and internal stressors occurring beyond the age of reproduction activates innate and adaptive immunity pathways involved in inflammatory response. Seventeen years after this theory was launched, it is now recognized that this phenomenon also involves non-immune cells, including adipocytes, fibroblasts, muscle, endothelial, and senescent cells. Recent data suggest that besides classical stimuli, such as cyto- megalovirus persistent infection (non-self), inflammging is fueled by a variety of stimuli derived from the gut microbiota (quasi-self) and by the continuous production of potentially inflammatory molecules released/secreted as a conse- quence of cell death and organelle dysfunction (self). All these products (alarmins) are sensed by a small number of evolutionary-selected sensors, and eventually activate few basic inflammatory pathways such as NF-\u3baB, inflammasomes, and cGAS. These phenomena are physiological and crucial for survival, but they undergo a progressive increase with age, sometimes reaching a threshold over which age-related pathologies ensue, thus representing an example of antagonist pleiotropy. Inflammaging is a dynamic phenomenon, and its final clinical outcome is highly \u201cpersonalized\u201d depending on what we propose to call \u201cimmunobiography,\u201d i.e., the lifelong immunological experiences and stimuli each individual has been exposed to. Finally, a particular attention is devoted to antiaging strategies, showing that most of them have a direct or indirect impact on inflammaging itself
Measurement of the B+ total cross section and B+ differential cross section d sigma/dp(T) in p(p)over-bar collisions at root s=1.8 TeV
We present measurements of the B+ meson total cross section and differential cross section dsigma/dp(T). The measurements use a 98+/-4 pb(-1) sample of p (p) over bar collisions at roots = 1.8 TeV collected by the CDF detector. Charged B meson candidates are reconstructed through the decay B+/- --> J/psiK(+/-) with J/psi --> mu(+)mu(-). The total cross section, measured in the central rapidity region \y\ 6.0 GeV/c, is 3.6+/-0.6(stat + syst) mub. The measured differential cross section is substantially larger than typical QCD predictions calculated to next-to-leading order