41262377
Convergence proof for optimized delta expansion: Anharmonic oscillator.
A recent proof of the convergence of the optimized δ expansion for one-dimensional non-Gaussian integrals is extended to the finite-temperature partition function of the quantum anharmonic oscillator. The convergence is exponentially fast, with the remainder falling as e −cN2/3 at order N in the expansion, independently of the size of the coupling or the sign of the mass term. In particular, the approach gives a convergent resummation procedure for the double-well (non-Borel-summable) case
117287068
A New Approach to QCD Sum Rules and Inclusive $\tau$ Decay
We show that renormalization group improvement, making use of analyticity and the structure of the operator product expansion, combined with a non-perturbative expansion method allows one to describe quarkonium states via QCD sum rules without the need for explicit power corrections. This technique also allows an accurate determination of parameters related to the inclusive decay of the $\tau$ lepton.
118655103
Comment on New ansatz for metric operator calculation in pseudo-Hermitian field theory
In a recent Brief Report by Shalaby, a new first-order perturbative calculation of the metric operator for an $i{\ensuremath{\phi}}^{3}$ scalar field theory is given. It is claimed that the incorporation of derivative terms in the ansatz for the metric operator results in a local solution, in contrast to the nonlocal solution previously obtained by Bender, Brody, and Jones. Unfortunately, Shalaby's calculation is not valid because of sign errors.
120377044
Electroproduction of isolated protons at high energy as a probe of the proton wave function in QCD
AbstractWe investigate the feasibility of using the process
$$eq \to ep\bar q\bar q$$
 as a means of determining the proton wave function which governs all exclusive processes involving protons. The calculation is performed in the limitŴ2≪Q2, whereŴ is the CM energy of the subprocess. The resulting expressions simplify considerably when an additional constraint is imposed excluding any hadrons accompanying the proton from a cone around it of half-angle θ≪1. However, a direct determination is still only possible in the case of a symmetric wave-function. A numerical exploration of the sensitivity of the cross-section to the parameters of an ansatz for the wave function shows a strong dependence on components which are not totally symmetric.
42992493
Interpolating Lagrangians and SU(2) gauge theory on the lattice.
We apply the linear {delta} expansion to non-Abelian gauge theory on the lattice, with SU(2) as the gauge group. We establish an appropriate parametrization and evaluate the average plaquette energy {ital E}{sub {ital P}} to {ital O}({delta}). As a check on our results, we recover the large-{beta} expansion up to {ital O}(1/{beta}{sup 2}), which involves some {ital O}({delta}{sup 2}) contributions. Using these contributions we construct a variant of the 1/{beta} expansion which gives a good fit to the data down to the transition region.
122803009
Gauge invariance and covariant Reggeization
SummaryBy the use of gauge-invariant couplings the formalism of covariant Reggeization is extended to deal with processes involving photons. Particular attention is paid to pion photoproduction, where Reggeized pion and nucleon exchange are shown to connect smoothly on to the elementary exchanges both from the form of the vertex couplings and form their respective contributions to the invariant amplitudes. In the latter approach the double-pole structure of the Coulomb Born terms is correctly reproduced. Pion Compton scattering is also studied as an archetypal two-photon process: here the problem of Pomeron Reggeization is similarly resolved. The Froissart-Gribov continuation is briefly discussed, as is the forward peak in π+ photoproduction.RiassuntoUsando gli accoppiamenti di invarianti di gauge si estende il formalismo della reggeizzazione covariante a trattare processi che coinvolgono i fotoni. Si dedica particolare attenzione alla fotoproduzione dei pioni, dimostrando che gli scambi reggeizzati del pione e del nucleone si raccordano agli scambi elementari sia per la forma degli accoppiamenti di vertice sia pei loro rispettivi contributi alle ampiezze invarianti. In quest'ultimo approccio si riproduce correttamente la struttura a poli doppi dei termini di Born coulombiani. Si studia anche lo scattering Compton del pione come un processo archetipo a due fotoni: in questo caso si risolve in modo analogo il problema della reggeizzazione del pomerone. Si discute brevemente la continuazione di Froissart-Gribov, come pure si discute il picco in avanti nella fotoproduzione del π+.РезюмеИспользуя калибровочно инвариантные связи, формлизм ковариантной реджеизации распространяется, чтобы рассмотреть процессы, включающие фотоны. Особенное внимание уделяется фоторождению пионов, где, как показывается, реджеизованный пионный и нуклонный обмен связаны плавно с элементарными обменами и из формы вершинных связей и из их сооттветствующих вкладов в инвариантные амплитуды. В последнем подходе корректно воспроизводится структура двойных полюсов кулоновских борновских членов. Также исследуется комптоновское рассеяние пионов, как архитипичный двух-фотонный процесс: где проблема реджеизации Померона разрешается аналогично. Вкратце обсуждается продолжение Фройссарта-Грибова, которое представляет пик вперед в π+ фоторождении.
124266533
Observation of mu e Events in anti-neutrino and Neutrino Interactions in the Fermilab 15-Foot Neon-H Bubble Chamber
125143796
An Exposure of the 15 foot bubble chamber with a neon - hydrogen mixture to a wideband neutrino beam from the Tevatron
29593010
Pion absorption above the Delta (1232) resonance.
Two-proton and three-proton inclusive [pi][sup +] absorption cross sections were measured for incident pion energies from 250 to 500 MeV on targets of [sup 12]C, [sup 58]Ni, [sup 90]Zr, [sup 118]Sn, and [sup 208]Pb using a large solid angle bismuth germanate detector array. Pion absorption events leading to three or more protons in the final state were observed to become more significant with increasing incident pion energy and were dominant at 500 MeV. The total absorption cross sections were inferred from analyses of the data with uncertanties of approximately 25%.
34597488
Left-right asymmetry in neutrino-produced hadron jets.
In an experiment (E546) to study interactions of {l angle}{ital E}{r angle}=100 GeV and {l angle}{ital Q}{sup 2}{r angle}=17 GeV{sup 2} neutrinos in the Fermilab 15-foot bubble chamber, we have looked for a left-right asymmetry in the azimuthal angle {phi} of individual hadrons about the direction of the lepton momentum transfer ({ital q} vector). Significant asymmetry is found for forward positive hadrons; for {ital x}{sub {ital F}}{gt}0.10, we find {l angle}cos{phi}{r angle}={minus}0.029{plus minus}0.008, where {ital x}{sub {ital F}} is the Feynman {ital x} variable. Negative hadrons with {ital x}{sub {ital F}}{gt}0.10 show no asymmetry, {l angle}cos{phi}{r angle}=0.004{plus minus}0.011. A model which includes parton intrinsic transverse momentum {ital k}{sub {ital t}} reproduces the asymmetry of combined positive and negative hadrons with {ital x}{sub {ital F}}{gt}0.10, {l angle}cos{phi}{r angle}={minus}0.018{plus minus}0.0065, if {l angle}{ital k}{sub {ital t}}{sup 2}{r angle}=0.065{plus minus}0.024 GeV{sup 2}/c{sup 2}. But the model predicts almost equal asymmetries for positive and negative hadrons. The model also agrees poorly with the observed dependence on the kinematic variables {ital x} and {ital Q}{sup 2} if the {ital k}{sub {ital t}} distribution is assumed to be independent of kinematic variables.
125826043
Study of Hadronic Systems Produced in electron-neutrino (anti-electron-neutrino) n e Interactions