259 research outputs found
Nitrogenous metabolism in Thoroughbred and Arabian foals from birth to five months of age
The maturation of nitrogen metabolism was studied in six Thoroughbred and six Arabian foals. Rectal temperature, heart and respiratory rates and serum concentration of several hematochemical parameters (total protein, urea, uric acid, creatinine, and albumine) were monitored from birth to 5 months of age. In both breeds, all the parameters except albumine showed significant differences over time (P<0.05). The two breeds did not differ from each other at any time point. Statistically significant decreases in urea and creatinine concentrations were related to the growth needs of foals during this critical period of development
BSM W W production with a jet veto
We consider the impact on W W production of the unique dimension-six operator coupling gluons to the Higgs field. In order to study this process, we have to appropriately model the effect of a veto on additional jets. This requires the resummation of large logarithms of the ratio of the maximum jet transverse momentum and the invariant mass of the W boson pair. We have performed such resummation at the appropriate accuracy for the Standard Model (SM) background and for a signal beyond the SM (BSM), and devised a simple method to interface jet-veto resummations with fixed-order event generators. This resulted in the fast numerical code MCFM-RE, the Resummation Edition of the fixed-order code MCFM. We compared our resummed predictions with parton-shower event generators and assessed the size of effects, such as limited detector acceptances, hadronisation and the underlying event, that were not included in our resummation. We have then used the code to compare the sensitivity of W W and Z Z production at the HL-LHC to the considered higher-dimension operator. We have found that W W can provide complementary sensitivity with respect to Z Z, provided one is able to control theory uncertainties at the percent-level. Our method is general and can be applied to the production of any colour singlet, both within and beyond the SM
The treatment of the infrared region in perturbative QCD
We discuss the contribution coming from the infrared region to NLO matrix
elements and/or coefficient functions of hard QCD processes. Strictly speaking,
this contribution is not known theoretically, since it is beyond perturbative
QCD. For DGLAP evolution all the infrared contributions are collected in the
phenomenological input parton distribution functions (PDFs), at some relatively
low scale Q_0; functions which are obtained from a fit to the `global' data.
However dimensional regularization sometimes produces a non-zero result coming
from the infrared region. Instead of this conventional regularization
treatment, we argue that the proper procedure is to first subtract from the NLO
matrix element the contribution already generated at the same order in \alpha_s
by the LO DGLAP splitting function convoluted with the LO matrix element. This
prescription eliminates the logarithmic infrared divergence, giving a
well-defined result which is consistent with the original idea that everything
below Q_0 is collected in the PDF input. We quantify the difference between the
proposed treatment and the conventional approach using low-mass Drell-Yan
production and deep inelastic electron-proton scattering as examples; and
discuss the potential impact on the `global' PDF analyses. We present arguments
to show that the difference cannot be regarded as simply the use of an
alternative factorization scheme.Comment: 15 pages, 5 figures, title changed, text considerably modified to
improve presentation, and discussion section enlarge
Physics at a 100 TeV pp collider: Higgs and EW symmetry breaking studies
This report summarises the physics opportunities for the study of Higgs
bosons and the dynamics of electroweak symmetry breaking at the 100 TeV pp
collider.Comment: 187 pages, 94 figures. Chapter 2 of the "Physics at the FCC-hh"
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