523 research outputs found
Phenomenology with a recoil-free jet axis: TMD fragmentation and the jet shape
We study the phenomenology of recoil-free jet axes using analytic
calculations and Monte Carlo simulations. Our focus is on the average energy as
function of the angle with the jet axis (the jet shape), and the energy and
transverse momenta of hadrons in a jet (TMD fragmentation). We find that the
dependence on the angle (or transverse momentum) is governed by a power law, in
contrast to the double-logarithmic dependence for the standard jet axis. The
effects of the jet radius, jet algorithm, angular resolution and grooming are
investigated. TMD fragmentation is important for constraining the structure of
the proton through semi-inclusive deep-inelastic scattering. These observables
are also of interest to the LHC, for example to constrain from
precision jet measurements, or probe the quark-gluon plasma in heavy-ion
collisions.Comment: 26 pages, 16 figures, version 2: matches Journal versio
Transverse momentum dependent distributions in and semi-inclusive deep-inelastic scattering using jets
The extraction of transverse momentum dependent distributions (TMDs) in
semi-inclusive deep inelastic scattering (SIDIS) is complicated by the presence
of both initial- and final-state nonperturbative physics. We recently proposed
measuring jets (instead of hadrons) as a solution, showing that for the
Winner-Take-All jet axis the same factorization formulae valid for hadrons
applied to jets of arbitrary size. This amounts to simply replacing TMD
fragmentation functions by our TMD jet functions. In this paper we present the
calculation of these jet functions at one loop. We obtain phenomenological
results for dijet (Belle II, LEP) and SIDIS (HERA, EIC) with a
jet, building on the arTeMiDe code. Surprisingly, we find that the limit of
large jet radius describes the full results extremely well, and we extract
the two-loop jet function in this limit using Event2, allowing us to achieve
NLL accuracy. We demonstrate the perturbative convergence of our
predictions and explore the kinematic dependence of the cross section. Finally,
we investigate the sensitivity to nonperturbative physics, demonstrating that
jets are a promising probe of proton structure.Comment: 41 pages, 9 figures. v4: fixed an important typo in table 1
concerning the scaling of modes, together with minor typos across the tex
Practical, reliable and inexpensive assay of lycopene in tomato products based on the combined use of light emitting diode (LED) and the optothermal window
Light emitting diode (LED) combined with the concept of optothermal window (OW) is proposed as a new approach (LED-OW) to detect lycopene in a wide range of tomato-based products (tomato juice, tomato ketchup, tomato passata and tomato puree). Phytonutrient lycopene is a dominant antioxidant in these products while beta-carotene is present in significantly lower quantities. Therefore for all practical reasons the interfering effect of beta-carotene at 502 nm analytical wavelength can be neglected. The LED-OW method is low-cost and simple, yet accurate and precise. The major attributes of the new method are its rapid speed of response and the fact that no preparation whatsoever of the sample is needed before the analysis. The lycopene found in tomato products studied here varies from 8 mg/100 g to 60 mg/100 g fresh product. Results obtained by LED-OW method were compared to the outcome of conventional, time consuming spectrophotometric methods and the correlation was very good (R = 0.98). Precision of the LED-OW instrumental setup ranged from 0.5 to 7.4%; the RSD achieved for lycopene-richest samples (= 40 mg/100 g) did not exceed 1.7%. Repeatability of analysis by LED-OW was found to vary between 0.7 and 7.1%
Transverse momentum dependent distributions with jets
We investigate the use of jets to measure transverse momentum dependent
distributions (TMDs). The example we use to present our framework is the dijet
momentum decorrelation at lepton colliders. Translating this momentum
decorrelation into an angle , we analyze the factorization of the
cross section for the cases , and ,
where is the jet radius. Critically, for the Winner-Take-All axis, the jet
TMD has the same double-scale renormalization group evolution as TMD
fragmentation functions for all radii . TMD fragmentation functions in
factorization theorems may then simply be replaced by the jet TMDs we
calculate, and all ingredients to perform the resummation to
next-to-next-to-leading logarithmic accuracy are available. Our approach also
applies to semi-inclusive deep inelastic scattering (SIDIS), where a jet
instead of a hadron is measured in the final state, and we find a clean method
to probe the intrinsic transverse momentum of quarks and gluons in the proton
that is less sensitive to final-state nonperturbative effects.Comment: 6 pages, 2 figure
Studying transverse momentum distributions with jets at NLL
Semi-inclusive deep inelastic scattering (SIDIS) is a promising channel for
the extraction of transverse momentum dependent distributions at future
colliders. In this context, we recently developed a framework that uses jets
(instead of single hadrons) to achieve reduced sensitivity to final-state
non-perturbative effects. A suitable non-standard jet definition allows us to
apply the factorization formulas valid for hadrons to jets of arbitrary size,
by just replacing fragmentation functions with the jet functions we computed.
Besides presenting the framework, we will show numerical predictions at NLL
accuracy.Comment: 6 pages, 2 figures. Contribution to the proceedings of DIS 2019
(Turin, Italy), to appear on Proceedings of Scienc
Position and Stiffness Control of One DoF Revolute Joint Using a Biphasic Media Variable Stiffness Actuator
At this time, several industrial processes and service tasks need safe interactions between humans and robots. This safety can be achieved using compliance design and control of mechanisms. This paper presents a compliant revolute joint mechanism using a variable stiffness actuator. The method for adapting the stiffness in the actuator includes a member onfigured to transmit motion that is connected to a fluidic circuit, into which a biphasic control fluid circulates. Actuator's stiffness is controlled by changing pressure of control fluid into distribution lines. The used control fluid is biphasic, composed of separated gas and liquid fractions with predefined ratio. A mathematical model of the actuator is presented, a modelbased control method is implemented to track the desired position and stiffness, and equations relating to the dynamics of the mechanism are provided. Results from force loaded and unloaded simulations and experiments with a physical prototype are discussed
Towards all-order factorization of QED amplitudes at next-to-leading power
We generalise the factorization of abelian gauge theory amplitudes to
next-to-leading power (NLP) in a soft scale expansion, following a recent
generalisation for Yukawa theory. From an all-order power counting analysis of
leading and next-to-leading regions, we infer the factorized structure for both
a parametrically small and zero fermion mass. This requires the introduction of
new universal jet functions, for non-radiative and single-radiative QED
amplitudes, which we compute at one-loop order. We show that our factorization
formula reproduces the relevant regions in one- and two-loop scattering
amplitudes, appropriately addressing endpoint divergences. It provides a
description of virtual collinear modes and accounts for non-trivial
hard-collinear interplay present beyond the one-loop level, making this a first
step towards a complete all-order factorization framework for gauge-theory
amplitudes at NLP.Comment: 31 pages, 18 figures. v2: as in journal versio
Modeling of a Cable-Based Revolute Joint Using Biphasic Media Variable Stiffness Actuation
In recent times, safe interactions between humans and robots are required for innumerable tasks and environments. This safety can be achieved using compliance design and control of mechanisms. Cable-driven mechanisms are used when applications need to have light structures, meaning that their actuators must be relocated to ground and forces are transferred along tensioned cables. This paper presents a compliant cable-driven revolute joint using biphasic media variable stiffness actuators. Actuator's stiffness is controlled by changing pressure of control fluid into distribution lines. The used control fluid is biphasic, composed of separated gas and liquid fractions with predefined ratio. The mathematical model of the actuator is presented along with its position and stiffness model-based control, then, equations relating to the dynamics of the mechanism are provided with a joint stiffness and orientation controller. Results from simulations are discussed
- …