8,425 research outputs found
Threshold Resummation for Higgs Production in Effective Field Theory
We present an effective field theory to resum the large double logarithms
originated from soft-gluon radiations at small final-state hadron invariant
masses in Higgs and vector boson (\gamma^*, and ) production at hadron
colliders. The approach is conceptually simple, indepaendent of details of an
effective field theory formulation, and valid to all orders in sub-leading
logarithms. As an example, we show the result of summing the
next-to-next-to-next leading logarithms is identical to that of standard pQCD
factorization method.Comment: A version to appear in Phys. Rev.
Phenomenology of flavor oscillations with non-perturbative effects from quantum field theory
We analyze phenomenological aspects of the quantum field theoretical
formulation of meson mixing and obtain the exact oscillation formula in the
presence of the decay. This formula is different from quantum mechanical
formula by additional high-frequency oscillation terms. In the infinite volume
limit, the space of the flavor quantum states is unitarily inequivalent to the
space of energy eigenstates
Collins-Soper Equation for the Energy Evolution of Transverse-Momentum and Spin Dependent Parton Distributions
The hadron-energy evolution (Collins and Soper) equation for all the
leading-twist transverse-momentum and spin dependent parton distributions is
derived in the impact parameter space. Based on the result, we present
resummation formulas for the spin structure functions in the semi-inclusive
deep inelastic scattering.Comment: 16 pages, 4 figures included, revised versio
Transverse Momentum Distribution Through Soft-Gluon Resummation in Effective Field Theory
We study resummation of transverse-momentum-related large logarithms
generated from soft-gluon radiations in soft-collinear effective field theory.
The anomalous dimensions of the effective quark and gluon currents, an
important ingredient for the resummation, are calculated to two-loop order. the
result at next-to-leading-log reproduces that obtained using the standard
method for deep-inelastic scattering, Drell-Yan process, and Higgs production
through gluon-gluon fusion. We comment on the extension of the calculation to
next-to-next-to-leading logarithms.Comment: 13 pages, one figur
Diversity of Urinary Tract Pathogens and Drug Resistant Isolates of Escherichia coli in different age and gender Groups of Pakistanis
Purpose: This paper was mainly aimed to investigate drug resistance of the various urinary tract infection (UTI) pathogens from patients of different gender and age groups of Pakistanis.
Method: For these purposes, urine samples of 109 patients were analyzed. Samples were screened on CLED agar. Antimicrobial susceptibility testing was performed by Kirby Bauer\'s disc diffusion method. Isolated colonies were processed for biochemical characterization and antibiotic sensitivity to ampicillin, amikacin, augmentin, ceftazidime, ceftriaxone, cefuroxime, cotrimoxazole, ciprofloxin, imipenem, meropenem, tazocine, trimethoprim, gentamicin and nitrofuratoin.
Result: E.Coli was found to be the most frequent causative agent of UTIs (66%) followed by Enterococci (8.3%), Candida spp. and Pseodomonas spp. (7.3% each), Klebsiella spp. (5.5%) and Enterobacter spp. (2.7%). Proteus. and Morgenella species were found in less than 1% of the cases. E.coli showed variable antimicrobial resistance to different antibiotics as 92%, 86%, 80%, 62%, 47%, 20% and 4% of the isolates were found to be resistant to ampicillin, cotrimoxazole, ciprofloxin, gentamicin, nitrofuratoin and amikacin, respectively.
Conclusion: The most effective in vitro agents were found to be amikacin followed by gentamicin (among the parenterals), and ciprofloxin among the orally administratered ones. A higher prevalence of UTIs was observed in the female population and E.coli showed no resistance to nitrofuratoin in age groups of 50+ and 70+ in both genders.
Keywords: Urinary tract infections, Age, Gender, Resistant microbes, E.coli. Tropical Journal of Pharmaceutical Research Vol. 7 (3) 2008: pp. 1025-103
Pseudoscalar meson decay constants and distribution amplitudes up to twist-4 in the light-front quark model
In the light-front quark model (LFQM) amenable to the simultaneous study of
both the mass spectroscopy and the wave function related observables, we
examine the decay constants and distribution amplitudes (DAs) up to the
twist-4. The analysis of the heavy pseudoscalar mesons is carried out both in
the and states. This investigation involves calculating the local and
nonlocal matrix elements using three
distinct current operators . Considering a general reference frame
where and investigating all available current components,
we examine not only the frame-independence but also the component-independence
of the decay constants. The explicit findings from our study provide the
evidence for the equality of the three pseudoscalar meson decay constants
obtained from the three distinct current operators . The notable
agreement in decay constants is attained by imposing the Bakamjian-Thomas
construction of the LFQM, namely the meson state is constructed by the
noninteracting quark and antiquark representations while the interaction is
added to the mass operator, which provides the self-consistency condition
replacing the physical mass with the invariant mass for the
noninteracting quark-antiquark representation of the meson state. In addition
to obtaining the process-independent pseudoscalar meson decay constant,
regardless of the choice of current operators , we further demonstrate
its explicit Lorentz and rotation invariance. In particular, we present the
analysis conducted on the twist-4 DA derived from the minus component of the
axial-vector current. Finally, we discuss the various twist DAs and their
-moments associated with the and heavy pseudoscalar mesons.Comment: 19 pages, 9 figures, 7 tables. Adding some reference
Riordan graphs I : structural properties
In this paper, we use the theory of Riordan matrices to introduce the notion of a Riordan graph. The Riordan graphs are a far-reaching generalization of the well known and well studied Pascal graphs and Toeplitz graphs, and also some other fami- lies of graphs. The Riordan graphs are proved to have a number of interesting (fractal) properties, which can be useful in creating computer networks with certain desirable features, or in obtaining useful information when designing algorithms to compute values of graph invariants. The main focus in this paper is the study of structural properties of families of Riordan graphs obtained from infinite Riordan graphs, which includes a fundamental decomposition theorem and certain conditions on Riordan graphs to have an Eulerian trail/cycle or a Hamiltonian cycle. We will study spectral properties of the Riordan graphs in a follow up paper
Riordan graphs II : spectral properties
The authors of this paper have used the theory of Riordan matrices to introduce the notion of a Riordan graph in [3]. Riordan graphs are proved to have a number of interesting (fractal) properties, and they are a far-reaching generalization of the well known and well studied Pascal graphs and Toeplitz graphs, and also some other families of graphs. The main focus in [3] is the study of structural properties of families of Riordan graphs obtained from certain infinite Riordan graphs. In this paper, we use a number of results in [3] to study spectral properties of Riordan graphs. Our studies include, but are not limited to the spectral graph invariants for Riordan graphs such as the adjacency eigenvalues, (signless) Laplacian eigenvalues, nullity, positive and negative inertia indices, and rank. We also study determinants of Riordan graphs, in particular, giving results about determinants of Catalan graphs
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