907 research outputs found
On the Role of Higher Twist in Polarized Deep Inelastic Scattering
The higher twist corrections to the spin dependent proton and
neutron structure functions are extracted in a model
independent way from experimental data on and found to be
non-negligible. It is shown that the NLO QCD polarized parton densities
determined from the data on g1, including higher twist effects, are in good
agreement with those found earlier from our analysis of the data on g1/F1 and
A1 where higher twist effects are negligible. On the contrary, the LO QCD
polarized parton densities obtained from the data on g1, including higher
twist, differ significantly from our previous results.Comment: 18 pages, latex, 6 figures, final version which will be published in
Phys. Rev. D, fig. 5 is changed, misprints in Table 2 are remove
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Mapping solar irradiance within Schrödinger Basin for future robotic sample return missions
The US National Research Council (NRC) identified eight scientific concepts and thirty-five prioritized investigations to be addressed with continued lunar exploration. These objectives are broadly consistent with those identified throughout the international community. the majority of these objectives require sample return from the Moon. Schrödinger basin has been highlighted as a particularly attractive location to find suitable samples
Intrinsic parton motion soft mechanisms and the longitudinal spin asymmetry A_LL in high energy pp -> pi X
The longitudinal double spin asymmetry A_LL in the reaction pp --> pi X has
been measured at RHIC with extremely interesting consequences. If the gluon
polarization in a proton were as big as needed to resolve the famous "spin
crisis" then A_LL would be large and positive. Latest RHIC results indicate
that A_LL is small and disfavour large positive values of the gluon
polarization. We examine whether the soft mechanisms (Collins, Sivers,
Boer-Mulders), essential for generating transverse single spin asymmetries,
have any significant influence on A_LL, and whether they could alter the
conclusion that the gluon polarization is necessarily small. It turns out that
the contribution from these effects is essentially negligible.Comment: RevTeX, 9 pages, 3 eps figures. Revised and shortened version; title
slightly modified; figs. 3,4 removed; a new figure for the unpol. cross
section added; no changes in results and conclusions; matches the published
versio
Can the polarization of the strange quarks in the proton be positive ?
Recently, the HERMES Collaboration at DESY, using a leading order QCD
analysis of their data on semi-inclusive deep inelastic production of charged
hadrons, reported a marginally positive polarization for the strange quarks in
the proton. We argue that a non-negative polarization is almost impossible.Comment: 6 pages, latex, minor changes in the discussion after Eq. (9
RANDOM GEOMETRIC GRAPHS AND ISOMETRIES OF NORMED SPACES
Given a countable dense subset S of a finite-dimensional normed space X, and 0 \u3c p \u3c 1, we form a random graph on S by joining, independently and with probability p, each pair of points at distance less than 1. We say that S is Rado if any two such random graphs are (almost surely) isomorphic. Bonato and Janssen showed that in ℓd∞ almost all S are Rado. Our main aim in this paper is to show that ℓd∞ is the unique normed space with this property: indeed, in every other space almost all sets S are non-Rado. We also determine which spaces admit some Rado set: this turns out to be the spaces that have an ℓ∞ direct summand. These results answer questions of Bonato and Janssen. A key role is played by the determination of which finite-dimensional normed spaces have the property that every bijective step-isometry (meaning that the integer part of distances is preserved) is in fact an isometry. This result may be of independent interest
Exploring the proton spin structure
Understanding the spin structure of the proton is one of the main challenges
in hadronic physics. While the concepts of spin and orbital angular momentum
are pretty clear in the context of non-relativistic quantum mechanics, the
generalization of these concepts to quantum field theory encounters serious
difficulties. It is however possible to define meaningful decompositions of the
proton spin that are (in principle) measurable. We propose a summary of the
present situation including recent developments and prospects of future
developments.Comment: 8 pages, 1 figure, 2 tables, contribution to the proceedings of the
DAE-BRNS High Energy Physics Symposium 2014, Dec 8-12, Guwahati, Indi
Stopping power of hot QCD plasma
The partonic energy loss has been calculated taking both the hard and soft
contributions for all the processes, revealing the importance of the
individual channels. Cancellation of the intermediate separation scale has been
exhibited. Subtleties related to the identical final state partons have
properly been taken into account. The estimated collisional loss is compared
with its radiative counter part. We show that there exists a critical energy
() below which the collisional loss is more than its radiative
counterpart. In addition, we present closed form formulas for both the
collision probabilities and the stopping power ()Comment: revised version, section added, 9pages with 5 figure
Liraglutide and Cardiovascular Outcomes in Type 2 Diabetes
Background The cardiovascular effect of liraglutide, a glucagon-like peptide 1 analogue, when added to standard care in patients with type 2 diabetes, remains unknown. Methods In this double-blind trial, we randomly assigned patients with type 2 diabetes and high cardiovascular risk to receive liraglutide or placebo. The primary composite outcome in the time-to-event analysis was the first occurrence of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke. The primary hypothesis was that liraglutide would be noninferior to placebo with regard to the primary outcome, with a margin of 1.30 for the upper boundary of the 95% confidence interval of the hazard ratio. No adjustments for multiplicity were performed for the prespecified exploratory outcomes. Results A total of 9340 patients underwent randomization. The median follow-up was 3.8 years. The primary outcome occurred in significantly fewer patients in the liraglutide group (608 of 4668 patients [13.0%]) than in the placebo group (694 of 4672 [14.9%]) (hazard ratio, 0.87; 95% confidence interval [CI], 0.78 to 0.97; P<0.001 for noninferiority; P=0.01 for superiority). Fewer patients died from cardiovascular causes in the liraglutide group (219 patients [4.7%]) than in the placebo group (278 [6.0%]) (hazard ratio, 0.78; 95% CI, 0.66 to 0.93; P=0.007). The rate of death from any cause was lower in the liraglutide group (381 patients [8.2%]) than in the placebo group (447 [9.6%]) (hazard ratio, 0.85; 95% CI, 0.74 to 0.97; P=0.02). The rates of nonfatal myocardial infarction, nonfatal stroke, and hospitalization for heart failure were nonsignificantly lower in the liraglutide group than in the placebo group. The most common adverse events leading to the discontinuation of liraglutide were gastrointestinal events. The incidence of pancreatitis was nonsignificantly lower in the liraglutide group than in the placebo group. Conclusions In the time-to-event analysis, the rate of the first occurrence of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke among patients with type 2 diabetes mellitus was lower with liraglutide than with placebo. (Funded by Novo Nordisk and the National Institutes of Health; LEADER ClinicalTrials.gov number, NCT01179048 .)
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