2,432 research outputs found
The Jet Shape at NLL
The jet shape is the fraction of the jet energy within a cone centered on
the jet axis. We calculate the jet shape distribution at next-to-leading
logarithmic accuracy plus next-to-leading order (NLL), accounting for
logarithms of both the jet radius and the ratio . This is the first
phenomenological study that takes the recoil of the jet axis due to soft
radiation into account, which is needed to reach this accuracy, but complicates
the calculation of collinear radiation and requires the treatment of rapidity
logarithms and non-global logarithms. We present numerical results, finding
good agreement with ATLAS and CMS measurements of the jet shape in an inclusive
jet sample, , for different kinematic bins. The effect of
the underlying event and hadronization are included using a simple
one-parameter model, since they are not part of our perturbative calculation.Comment: 36 pages, 14 figures, v2: extended discussion of non-global
logarithms, journal versio
Wake interaction and power production of variable height model wind farms
Understanding wake dynamics is an ongoing research topic in wind energy, since wakes have considerable effects on the power production when wind turbines are placed in a wind farm. Wind tunnel experiments have been conducted to study the wake to wake interaction in a model wind farm in tandem with measurements of the extracted power. The aim is to investigate how alternating mast height influences the interaction of the wakes and the power production. Via the use of stereo-particle image velocimetry, the flow field was obtained in the first and last rows of the wind turbine array as a basis of comparison. It was found that downstream of the exit row wind turbine, the power was increased by 25% in the case of a staggered height configuration. This is partly due to the fact that the taller turbines reach into a flow area with a softened velocity gradient. Another aspect is that the wake downstream of a tall wind turbine to some extent passes above the standard height wind turbine. Overall the experiments show that the velocity field downstream of the exit row changes considerably when the mast height is alternating
Calculating the angle between jet axes
We study the angle between i) the standard jet axis, ii) the axis of a jet
which has been groomed using soft drop, with reduced sensitivity to soft
radiation, iii) the jet axis obtained with the winner-take-all recombination
scheme, which is insensitive to soft radiation at leading power. We calculate
the distributions for these angles at next-to-leading logarithmic accuracy,
including non-global logarithms. The angle between the standard and groomed jet
axis directly probes soft wide-angle radiation, leading to a novel
factorization formula. This angle is also very sensitive to nonperturbative
physics, which is directly connected to nonperturbative contribution to the
rapidity anomalous dimension for transverse momentum distributions. Comparing
our predictions to Pythia we find good agreement, and we foresee applications
to jet substructure in proton-proton and heavy ion collisions.Comment: 39 pages, 13 figure
Observations on Acidosis Through Continual Feed Intake and Ruminal pH Monitoring
A system of continual data acquisition of feed intake and ruminal pH has been developed for studying subacute acidosis in finishing steers. Feed intake is monitored with feedbunks which are suspended from weigh cells. Ruminal pH is monitored with submersible pH electrodes suspended in the rumen. Numerous anecdotal observations of subacute acidosis have been made throughout the feeding periods of several steers, providing information unlikely to be recognized during a planned trial. Therefore, this model for studying subacute acidosis offers many unique opportunities for enhancing our understanding of the interactions between feed intake and acidosis
The spectrum for Higgs production via heavy quark annihilation at NLL+aNLO
We study the transverse momentum () spectrum of the Higgs boson produced
via the annihilation of heavy quarks () in proton-proton collisions.
Using soft-collinear effective theory (SCET) and working in the five-flavour
scheme, we provide predictions at three-loop order in resummed perturbation
theory (NLL). We match the resummed calculation to full fixed-order
results at next-to-next-to-leading order (NNLO), and introduce a decorrelation
method to enable a consistent matching to an approximate NLO (aNLO)
result. Since the -quark initiated process exhibits large nonsingular
corrections, it requires special care in the matching procedure and estimation
of associated theoretical uncertainties, which we discuss in detail. Our
results constitute the most accurate predictions to date for these processes in
the small region and could be used to improve the determination of Higgs
Yukawa couplings from the shape of the measured Higgs spectrum.Comment: 25 pages + 11 appendix + references, 18 figure
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