23,791 research outputs found
A one-dimensional tunable magnetic metamaterial
We present experimental data on a one-dimensional superconducting
metamaterial that is tunable over a broad frequency band. The basic building
block of this magnetic thin-film medium is a single-junction (rf-)
superconducting quantum interference device (SQUID). Due to the nonlinear
inductance of such an element, its resonance frequency is tunable in situ by
applying a dc magnetic field. We demonstrate that this results in tunable
effective parameters of our metamaterial consisting of 54 SQUIDs. In order to
obtain the effective magnetic permeability from the measured data, we employ a
technique that uses only the complex transmission coefficient S21
Charge density wave in hidden order state of URuSi
We argue that the hidden order state in URuSi will induce a charge
density wave. The modulation vector of the charge density wave will be twice
that of the hidden order state, . To illustrate how the
charge density wave arises we use a Ginzburg-Landau theory that contains a
coupling of the charge density wave amplitude to the square of the HO order
parameter . This simple analysis allows us to predict the
intensity and temperature dependence of the charge density wave order parameter
in terms of the susceptibilities and coupling constants used in the
Ginzburg-Landau analysis.Comment: 8 pages, 4 figure
Charmonia production from -hadron decays at LHC with -factorization: , and
We consider the production of and mesons originating from
the decays of -flavored hadrons at the LHC using the -factorization
approach. Our analysis covers both inclusive charmonia production and
production of mesons in association with bosons. We apply the
transverse momentum dependent (or unintegrated) gluon density in a proton
derived from Catani-Ciafaloni-Fiorani-Marchesini (CCFM) evolution equation and
adopt fragmentation functions based on the non-relativistic QCD factorization
to describe the inclusive -hadron decays into the different charmonium
states. Our predictions agree well with latest experimental data taken by the
CMS, ATLAS and LHCb Collaborations at , and ~TeV. The
contributions from double parton scattering to the associated non-prompt
production are estimated and found to be small.Comment: 12 pages, 5 figure
Testing the parton evolution with the use of two-body final states
We consider the production of quarks and Drell-Yan lepton pairs at
LHC conditions focusing attention on the total transverse momentum of the
produced pair and on the azimuthal angle between the momenta of the outgoing
particles. Plotting the corresponding distributions in bins of the final state
invariant mass, one can reconstruct the full map of the transverse momentum
dependent parton densities in a proton. We give examples of how can these
distributions can look like at the LHC energies.Comment: 8 pages, 7 figure
Soft-gluon resolution scale in QCD evolution equations
QCD evolution equations can be recast in terms of parton branching processes.
We present a new numerical solution of the equations. We show that this
parton-branching solution can be applied to analyze infrared contributions to
evolution, order-by-order in the strong coupling , as a function of
the soft-gluon resolution scale parameter. We examine the cases of
transverse-momentum ordering and angular ordering. We illustrate that this
approach can be used to treat distributions which depend both on longitudinal
and on transverse momenta.Comment: Latex, 8 pages, 4 figure
Investigation of beauty production and parton shower effects at LHC
We present hadron-level predictions from the Monte Carlo generator Cascade
and parton level calculations of open b quark, b-flavored hadron and inclusive
b-jet production in the framework of the kt-factorization QCD approach for the
LHC energies. The unintegrated gluon densities in a proton are determined using
the CCFM evolution equation and the Kimber-Martin-Ryskin (KMR) prescription.
Our predictions are compared with the first data taken by the CMS and LHCb
collaborations at 7 TeV. We study the theoretical uncertainties of our
calculations and investigate the effects coming from parton showers in initial
and final states. The special role of initial gluon transverse momenta in
description of the data is pointed out.Comment: 19 pages, 11 figures. arXiv admin note: substantial text overlap with
arXiv:1105.507
Collinear and TMD Quark and Gluon Densities from Parton Branching Solution of QCD Evolution Equations
We study parton-branching solutions of QCD evolution equations and present a
method to construct both collinear and transverse momentum dependent (TMD)
parton densities from this approach. We work with next-to-leading-order (NLO)
accuracy in the strong coupling. Using the unitarity picture in terms of
resolvable and non-resolvable branchings, we analyze the role of the soft-gluon
resolution scale in the evolution equations. For longitudinal momentum
distributions, we find agreement of our numerical calculations with existing
evolution programs at the level of better than 1 percent over a range of five
orders of magnitude both in evolution scale and in longitudinal momentum
fraction. We make predictions for the evolution of transverse momentum
distributions. We perform fits to the high-precision deep inelastic scattering
(DIS) structure function measurements, and we present a set of NLO TMD
distributions based on the parton branching approach.Comment: 27 pages, 8 figure
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