714 research outputs found
NLO corrections in the initial-state parton shower Monte Carlo
The decade-old technique of combining NLO-corrected hard process with
LO-level parton shower Monte Carlo is now mature and used in practice of the
QCD calculations in the LHC data analysis. The next step, its extension to an
NNLO-corrected hard process combined with the NLO-level parton shower Monte
Carlo, will require development of the latter component. It does not exist yet
in a complete form. In this note we describe recent progress in developing the
NLO parton shower for the initial-state hadron beams. The technique of adding
NLO corrections in the fully exclusive form (defined in recent years) is now
simplified and tested numerically, albeit for a limited set of NLO diagrams in
the evolution kernels.Comment: 8 pages, 5 figure
On the dependence of QCD splitting functions on the choice of the evolution variable
We show that already at the NLO level the DGLAP evolution kernel Pqq starts
to depend on the choice of the evolution variable. We give an explicit example
of such a variable, namely the maximum of transverse momenta of emitted partons
and we identify a class of evolution variables that leave the NLO Pqq kernel
unchanged with respect to the known standard MS-bar results. The kernels are
calculated using a modified Curci-Furmanski-Petronzio method which is based on
a direct Feynman-graphs calculation.Comment: 16 pages, 4 figure
New simpler method of matching NLO corrections with parton shower Monte Carlo
Next steps in development of the KrkNLO method of implementing NLO QCD
corrections to hard processes in parton shower Monte Carlo programs are
presented. This new method is a simpler alternative to other well-known
approaches, such as MC@NLO and POWHEG. The KrkNLO method owns its simplicity to
the use of parton distribution functions (PDFs) in a new, so-called Monte Carlo
(MC), factorization scheme which was recently fully defined for the first time.
Preliminary numerical results for the Higgs-boson production process are also
presented.Comment: 8 pages, 5 JPG figures, conference: "Loops and Legs in Quantum Field
Theory", 24-29 April 2016, Leipzig, German
Matching NLO QCD with parton shower in Monte Carlo scheme - the KrkNLO method
A new method of including the complete NLO QCD corrections to hard processes
in the LO parton-shower Monte Carlo (PSMC) is presented. This method, called
KrkNLO, requires the use of parton distribution functions in a dedicated Monte
Carlo factorization scheme, which is also discussed in this paper. In the
future, it may simplify introduction of the NNLO corrections to hard processes
and the NLO corrections to PSMC. Details of the method and numerical examples
of its practical implementation, as well as comparisons with other
calculations, such as MCFM, MC@NLO, POWHEG, for single -boson
production at the LHC, are presented.Comment: 50 pages, 14 figures. Version published in JHEP: added a comparison
of krkNLO results and the fixed-order NNLO result from the DYNNLO program and
addressed several points raised by the refere
Path to the Theoretical Luminosity Precision Requirement for the FCC-ee (and ILC)
We present pathways to the required theoretical precision for the luminosity
targeted by the FCC-ee precision studies. We put the discussion in context by
reviewing briefly the situation at the time of LEP. We then present the current
status and routes to the desired 0.01\% targeted by the FCC-ee (as well as by
the ILC).Comment: 6 pages, 2 tables; talk presented at the International Workshop on
Future Linear Colliders (LCWS2018), Arlington, Texas, 22-26 October 2018.
C18-10-22; typos corrected; misprint correcte
Relationship between be-derived erosion rates and mean annual precipitation, vegetation type, and precipitation variability
Millenial scale erosion rates derived from cosmogenic nuclides generally suggest that a relationship between precipatation and erosion rate is absent or negligible, depite the fact that water is the main agent of erosion. Here, we acknowledge that slope has a strong primary correlation with erosion rate and examine a new 10BE compilation to determine if mean annual precipatation has significan secondary control on erosion rates
Gamma Factory high-intensity muon and positron source -- exploratory studies
One of the fundamental challenges for the future leptonic colliders and
neutrino factories as well as for the high-sensitivity studies of lepton
universality is to design and construct new high-intensity sources of muons and
positrons. The next-generation sources should increase the intensity of the
presently operating ones by at least three orders of the magnitude and include
an important option of producing longitudinally polarised leptons. The main
effort to achieve this goal has been focused, so far, on the proton-beam-driven
muon sources and electron-beam-driven positron sources. In this paper, we
present exploratory studies of an alternative scheme which is based on
high-intensity megawatt-class photon beams. Such beams could be delivered in
the future by the Gamma Factory (GF) project. One of the GF multiple goals is
to increase the energy range (by more than one order of magnitude) and the
intensity (by more than six orders of magnitude) of the presently operating
photon sources. Such a leap can be achieved by extending the present
hadron-collider modus operandi of the LHC with the new GF-operation-mode,
allowing to collide atomic beams with laser pulses. The exploratory studies
presented in this paper demonstrate that more than 10 muons of both
signs and more than 10 electrons/positrons per second can be produced by
the GF source
Fuzzy cellular model for on-line traffic simulation
This paper introduces a fuzzy cellular model of road traffic that was
intended for on-line applications in traffic control. The presented model uses
fuzzy sets theory to deal with uncertainty of both input data and simulation
results. Vehicles are modelled individually, thus various classes of them can
be taken into consideration. In the proposed approach, all parameters of
vehicles are described by means of fuzzy numbers. The model was implemented in
a simulation of vehicles queue discharge process. Changes of the queue length
were analysed in this experiment and compared to the results of NaSch cellular
automata model.Comment: The original publication is available at http://www.springerlink.co
New Results on Precision Studies of Heavy Vector Boson Physics
We present new results for two important heavy vector boson physics
processes: (1), virtual corrections to hard bremsstrahlung which are relevant
to precision predictions for the radiative return process in Z boson production
at and beyond LEP2 energies ; and, (2), electric charge screening effects in
single W production with finite p_T, multiple photon radiation in high energy
collider physics processes. In both cases we show that we improve the
respective precision tag significantly. Phenomenological implications are
discussed.Comment: 5 pages, 2 figures; to appear in Proc. DPF200
Networking Aspects based on the Talkative Power Concept for DC Microgrid Systems
The talkative power concept is a simultaneous power-line communication and energy transfer technique which integrates data modulation into a power converter. The information sequence is deterministically represented by the ripple, which superimposes the output voltage. With a few exceptions, so far emphasis has been on scenarios where only a single node is actively transmitting data in a certain time slot in simplex mode. In microgrid applications, however, multiple active power sources are of interest as well. Examples include battery management systems, smart metering, electricity trading systems, and smart grids with several power sources, energy storage devices, loads, and data receivers. In this contribution, bus networking aspects based on the talkative power concept are presented for scenarios with several active nodes and for full-duplex communication. The paper addresses potential multiple access techniques as well as duplexing schemes for connected power converters supporting bidirectional power and information flow. In numerical results, a spread spectrum scheme based on orthogonal variable spreading factor codes in conjunction with frequency shift keying (FSK) is presented for four simultaneously active buck converters with a sum data rate of 500 kbps at a switching frequency of 1 MHz. In general, with 2-ary FSK, the maximum achievable sum data rate is half of the switching frequency in a synchronous setup
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