440 research outputs found
Proton structure, an iridescent study: from parton distributions to the emergence of the proton mass
Factorization for quasi-TMD distributions of sub-leading power
The quasi-transverse-momentum dependent (qTMD) distributions are equal-time
correlators that can be computed within the lattice QCD approach. In the regime
of large hadron's momentum, qTMD distributions are expressed in terms of
standard TMD distributions via the factorization theorem. We derive the
corresponding factorization theorem at the next-leading power (NLP), and, for
the first time, we present the factorized expressions for a large class of qTMD
distributions of sub-leading power. The NLP expression contains TMD
distributions of twist-two, twist-three, and a new lattice-specific
nonperturbative function. We point out that some of the qTMD distributions
considered in this work can be employed to extract the Collins-Soper kernel
using the standard techniques of different-momenta-ratio. We provide NLO
expressions for all the elements of the factorization theorem. Also, for the
first time, we explicitly demonstrate the restoration of boost invariance in
NLP TMD factorization.Comment: 34 pages, 4 figures, 1 tabl
Chloramphenicol restores the polymorphonuclear accumulation in carrageenin-induced pleurisy in diabetic rats
We investigated the effect of chloramphenicol succinate (30 mg/kg, every 12 h for 4 days, ip) on the reduced polymorphonuclear leukocytes (PMN) accumulation in carrageenin-induced pleurisy (150 mug) in diabetic (alloxan, 40 mg/kg, IV) rats (Wistar, males, 180-320 g, n = 12). Chloramphenicol produced an increase (p<0.05) on PMN count in pleural exudate of 36% in normal animals. In the animals non-treated with chloramphenicol the diabetes state reduced (p<0.05) the accumulation of PMN cells by 45%. In diabetic animals treated with chloramphenicol the number of PMN in pleural exudate was similar to the one observed in the control group. Total and differential counts of leukocytes in the peripheral blood were similar between groups before and 4 h after the carrageenin-injection.Investigou-se o efeito do succinato de cloranfenicol (30 mg/kg, a cada 12 h, durante 4 dias, IP) sobre o acúmulo de leucócitos polimorfonucleares (PMN) na pleurisia induzida pela carragenina (150 mig) em ratos (Wistar, machos, 180-230 g, n = 12) diabéticos (40 mg/kg de aloxana, IV). O antibiótico produziu aumento de 36% no número de PMN (p<0,05) migrados para a cavidade pleural de animais normais. O estado diabético provocou redução de 45% dos PMN (p<0,05) acumulados no exsudato pleural de animais não tratados com o antibiótico. Por outro lado, animais diabéticos tratados com succinato de cloranfenicol apresentaram resposta de PMN que não diferiu estatisticamente do observado em animais controle, não tratados. A contagem total e diferencial dos leucócitos circulantes realizada antes e 4 h depois da aplicação da carragenina não diferiu estatisticamente entre os grupos
Definition and evolution of transverse momentum dependent distribution of twist-three
We present an in-depth analysis of transverse momentum dependent (TMD)
distributions of twist-three. In particular, we focus on evolution equations,
symmetry relations, parameterization, interpretation, small-b asymptotic
behaviour and the structure of singularities. The starting point of discussion
are the correlators with the definite TMD-twist. By considering suitable
combinations of these correlators, we introduce physical TMD distribution of
twist-three that can be used for practical applications. We also establish
relations with generic TMD distribution of twist-three, and demonstrate that
their evolution equations are autonomous in the large- limit.Comment: 43 pages, 5 figure
Composite Laminate With Coefficient of Thermal Expansion Matching D263 Glass
The International X-ray Observatory project seeks to make an X-ray telescope assembly with 14,000 flexible glass segments. The glass used is commercially available SCHOTT D263 glass. Thermal expansion causes the mirror to distort out of alignment. A housing material is needed that has a matching coefficient of thermal expansion (CTE) so that when temperatures change in the X-ray mirror assembly, the glass and housing pieces expand equally, thus reducing or eliminating distortion. Desirable characteristics of this material include a high stiffness/weight ratio, and low density. Some metal alloys show promise in matching the CTE of D263 glass, but their density is high compared to aluminum, and their stiffness/weight ratio is not favorable. A laminate made from carbon fiber reinforced plastic (CFRP) should provide more favorable characteristics, but there has not been any made with the CTE matching D263 Glass. It is common to create CFRP laminates of various CTEs by stacking layers of prepreg material at various angles. However, the CTE of D263 glass is 6.3 ppm/ C at 20 C, which is quite high, and actually unachievable solely with carbon fiber and resin. A composite laminate has been developed that has a coefficient of thermal expansion identical to that of SCHOTT D263 glass. The laminate is made of a combination of T300 carbon fiber, Eglass, and RS3C resin. The laminate has 50% uni-T300 plies and 50% uni-E-glass plies, with each fiber-layer type laid up in a quasi-isotropic laminate for a total of 16 plies. The fiber volume (percent of fiber compared to the resin) controls the CTE to a great extent. Tests have confirmed that a fiber volume around 48% gives a CTE of 6.3 ppm/ C. This is a fairly simple composite laminate, following well established industry procedures. The unique feature of this laminate is a somewhat unusual combination of carbon fiber with E-glass (fiberglass). The advantage is that the resulting CTE comes out to 6.3 ppm/ C at 20 C, which matches D263 glass. The trick with this laminate is to establish the proper fiber volume to get the desired CTE. Laminates were made with several different fiber volumes and coupons were tested to establish the relationship between fiber volume and CTE. Testing proved that fiber volume should be about 48%
Revisiting model relations between T-odd transverse-momentum dependent parton distributions and generalized parton distributions
We revisit the connection between generalized parton distributions in impact
parameter space and T-odd effects in single spin asymmetries of the
semi-inclusive deep inelastic process. We show that nontrivial relations can be
established only under very specific conditions, typically realized only in
models that describe hadrons as two-body bound systems and involving a
helicity-conserving coupling between the gauge boson and the spectator system.
Examples of these models are the the scalar-diquark spectator model or the
quark-target model for the nucleon, and relativistic models for the pion at the
lowest order in the Fock-space expansion.Comment: 15 pages, 2 figures, 1 table, v2: list of references has been
correcte
The gravitational form factor D(t) of the electron
The electron-graviton interaction can be described in terms of the
gravitational form factors of the QED energy momentum tensor. Here we focus on
the form factor D(t), and we examine its properties and its interpretation in
terms of internal forces at one-loop accuracy in QED. We perform the
calculation by keeping separate the contributions due to the electron and the
photon parts of the energy momentum tensor. We also study the case of a nonzero
photon mass. Furthermore, we discuss similarities with and differences to the
form factor D(t) of hadronic bound states.Comment: 18 pages, 6 figures; accepted for publication in Phys. Lett.
A model for pion collinear parton distribution function and form factor
We developed a model for the pion light-front wave function (LFWF) that
incorporates valence, sea and gluon degrees of freedom. Using the LFWF overlap
representation, we derived parametrizations for the pion parton distribution
functions and the electromagnetic form factor. These parametrizations depend on
two distinct sets of parameters, enabling separate fits of the longitudinal-
and transverse-momentum dependencies of the LFWF. The pion PDFs are extracted
from available Drell-Yan and photon-production data using the xFitter framework
and are found well compatible with existing extractions. Furthermore, the fit
of the electromagnetic form factor of the pion to all the available
experimental data works quite successfully.Comment: 5 pages, 5 figures. Contribution presented at DIS202
- …