787 research outputs found
Derivation of Covariant Dissipative Fluid Dynamics in the Renormalization-group Method
We derive generic relativistic hydrodynamical equations with dissipative
effects from the underlying Boltzmann equation in a mechanical and systematic
way on the basis of so called the renormalization-group (RG) method. A
macroscopic frame vector is introduced to specify the frame on which the
macroscopic dynamics is described. Our method is so mechanical with only few
ansatz that our method give a microscopic foundation of the available
hydrodynamical equations, and also can be applied to make a reduction of the
kinetic equations other than the simple Boltzmann equation.Comment: Serious typos and a minor one are corrected in p.6 and 7, and in p.1,
respectivel
Survival of charmonia above Tc in anisotropic lattice QCD
We find a strong evidence for the survival of and as
spatially-localized (quasi-)bound states above the QCD critical
temperature , by investigating the boundary-condition dependence of their
energies and spectral functions. In a finite-volume box, there arises a
boundary-condition dependence for spatially spread states, while no such
dependence appears for spatially compact states. In lattice QCD, we find almost
{\it no} spatial boundary-condition dependence for the energy of the
system in and channels for . We also
investigate the spectral function of charmonia above in lattice QCD using
the maximum entropy method (MEM) in terms of the boundary-condition dependence.
There is {\it no} spatial boundary-condition dependence for the low-lying peaks
corresponding to and around 3GeV at . These facts
indicate the survival of and as compact
(quasi-)bound states for .Comment: 4 pages, 1 figur
Search for doubly charged Higgs bosons using the same-sign diboson mode at the LHC
Doubly charged Higgs bosons are predicted in many new physics models with an
extended Higgs sector that contains a Higgs triplet field. Current experimental
searches have been focusing mainly on the scenario in which the same-sign
dilepton decay modes are the dominant ones. We study the scenario where the
vacuum expectation value of the triplet field is sufficiently large so that the
associated charged Higgs bosons decay dominantly to a pair of weak gauge bosons
instead. A detailed simulation of the signal and the backgrounds is performed
for the CERN Large Hadron Collider at the collision energy of 8 TeV and 14 TeV.
We find that different cuts should be imposed for the events, depending on
whether the doubly charged Higgs boson mass is greater than about 200 GeV. In
the higher mass region, the forward jet tagging proves to be useful in
enhancing the signal significance. We show the discovery reach of the LHC
running at 8 and 14 TeV, with two benchmark triplet vacuum expectation values.
With an integrated luminosity of 10 fb at 8 TeV, the doubly charged
Higgs boson with a mass of GeV can be tested at level in
such a scenario.Comment: 18 pages, 10 figures; published in Physical Review
Yukawa Matrix for the Neutrino and Lepton Flavour Violation
We estimate the magnitude of Lepton Flavour Violation (LFV) from the phase of
the neutrino Yukawa matrix. In the minimal supersymmetric standard model with
right-handed neutrinos, the LFV processes l_i \to l_j \gamma can appear through
the slepton mixing, which comes from the renormalization group effect on the
right-handed neutrino Yukawa interaction between the Grand Unified Theory scale
and the heavy right-handed neutrino mass scale. Two types of phases exist in
the neutrino Yukawa matrix. One is the Majorana phase, which can change the
magnitude of the LFV branching ratios by a few factor. The other phases relate
for the size of the Yukawa hierarchy and its phase effect can change the LFV
branching ratios by several orders of magnitude.Comment: Talk given by K. Tsumura at NuFact04, Osaka, Japan, July 26 - August
1,2004 - 3 pages, 2 figure
Suboptimal quantum-error-correcting procedure based on semidefinite programming
In this paper, we consider a simplified error-correcting problem: for a fixed
encoding process, to find a cascade connected quantum channel such that the
worst fidelity between the input and the output becomes maximum. With the use
of the one-to-one parametrization of quantum channels, a procedure finding a
suboptimal error-correcting channel based on a semidefinite programming is
proposed. The effectiveness of our method is verified by an example of the
bit-flip channel decoding.Comment: 6 pages, no figure, Some notations differ from those in the PRA
versio
Relativistic dissipative hydrodynamics with extended matching conditions for ultra-relativistic heavy-ion collisions
Recently we proposed a novel approach to the formulation of relativistic
dissipative hydrodynamics by extending the so-called matching conditions in the
Eckart frame [Phys. Rev. {\bf C 85}, (2012) 14906]. We extend this formalism
further to the arbitrary Lorentz frame. We discuss the stability and causality
of solutions of fluid equations which are obtained by applying this formulation
to the Landau frame, which is more relevant to treat the fluid produced in
ultra-relativistic heavy-ion collisions. We derive equations of motion for a
relativistic dissipative fluid with zero baryon chemical potential and show
that linearized equations obtained from them are stable against small
perturbations. It is found that conditions for a fluid to be stable against
infinitesimal perturbations are equivalent to imposing restrictions that the
sound wave, , propagating in the fluid, must not exceed the speed of light
, i.e., . This conclusion is equivalent to that obtained in the
previous paper using the Eckart frame [Phys. Rev. {\bf C 85}, (2012) 14906].Comment: 2nd version. Typos corrected. 7 pages. Contribution to The European
Physical Journal A (Hadrons and Nuclei) topical issue about 'Relativistic
Hydro- and Thermodynamics in Nuclear Physics
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