226 research outputs found
On the Extraction of Low-energy Constants of Single- and Double- Decays from Lattice QCD: A Sensitivity Analysis
Lattice quantum chromodynamics (LQCD) has the promise of constraining
low-energy constants (LECs) of nuclear effective field theories (EFTs) from
first-principles calculations that incorporate the dynamics of quarks and
gluons. Given the Euclidean and finite-volume nature of LQCD outputs, complex
mappings are developed in recent years to obtain the Minkowski and
infinite-volume counterparts of LQCD observables. In particular, as LQCD is
moving toward computing a set of important few-nucleon matrix elements at the
physical values of the quark masses, it is important to investigate whether the
anticipated precision of LQCD spectra and matrix elements will be sufficient to
guarantee tighter constraints on the relevant LECs than those already obtained
from phenomenology, considering the non-trivial mappings involved. With a focus
on the leading-order LECs of the pionless EFT, and ,
which parametrize, respectively, the strength of the isovector axial two-body
current in a single- decay (and other related processes such
fusion), and of the isotensor contact two-body operator in the neutrinoless
double- decay within the light neutrino exchange scenario, the expected
uncertainty on future extractions of and are examined
using synthetic data at the physical values of the quark masses. It is observed
that achieving small uncertainties in will be challenging, and
(sub)percent-level precision in the two-nucleon spectra and matrix elements is
essential in reducing the uncertainty on this LEC compared to the existing
constraints. On the other hand, the short-distance coupling of the neutrinoless
double- decay, , is shown to be less sensitive to
uncertainties on both LQCD energies and the matrix element, and can likely be
constrained with percent-level precision in the upcoming LQCD calculations.Comment: 24 pages, 8 figure
Lagrangian tracers on a surface flow: the role of time correlations
Finite time correlations of the velocity in a surface flow are found to be
important for the formation of clusters of Lagrangian tracers. The degree of
clustering characterized by the Lyapunov spectrum of the flow is numerically
shown to be in qualitative agreement with the predictions for the white-in-time
compressible Kraichnan flow, but to deviate quantitatively. For intermediate
values of compressibility the clustering is surprisingly weakened by time
correlations.Comment: 4 pages, 5 figures, to be published in PR
A novel composite web service selection based on quality of service
Using the internet, as a dynamic environment thanks to its distributed characteristic, for web service deployment has become a crucial issue in QoS-driven service composition. An accurate adaption should be undertaken to provide a reliable service composition which enables the composited services are being executed appropriately. That is, the critical aspect of service composition is the proper execution of combination of web services while the appropriate service adaption performed with respect to predetermined functional and non-functional characteristics. In this paper, we attempts to deliberate the optimization approaches to devise the appropriate scheme for QoS-based composite web service selection
Closure of two dimensional turbulence: the role of pressure gradients
Inverse energy cascade regime of two dimensional turbulence is investigated
by means of high resolution numerical simulations. Numerical computations of
conditional averages of transverse pressure gradient increments are found to be
compatible with a recently proposed self-consistent Gaussian model. An
analogous low order closure model for the longitudinal pressure gradient is
proposed and its validity is numerically examined. In this case numerical
evidence for the presence of higher order terms in the closure is found. The
fundamental role of conditional statistics between longitudinal and transverse
components is highlighted.Comment: 4 pages, 2 figures, in press on PR
Improved battery life for context awareness application in smart-phones
The new smart-phones with new operating system and portable sensors support the basis for context awareness systems and applications for handling user activity and user privacy. Nowadays, individuals need new services and real time information anywhere and anytime. Context awareness is an emerging service, which could be able to improve the user experiences in current situation. Context awareness can be considered as location, calendar, user activity and etc. The review of the literature proves that context awareness in mobile phone can be useful and studied as unavoidable service in next generation of smart-phone applications. In this paper, a short review about context awareness in mobile phone is studied, furthermore, we critically analyzed related works of context awareness in smart-phones. The review shows that the most important context in mobile phone is location, which is mostly obtained by using Global Positioning System (GPS) sensor in mobile phones but GPS can significantly increases battery consumption in mobile phones. In this regard, a framework as Improved Battery life in Context Awareness System (IBCS) is proposed to improve battery life and reduce cost of using GPS in context awareness applications based on smart-phones. The review argues the weakness and strength of these studies, and aims to (a) indicate the most important context in mobile phone, (b) reduce the battery consumption of GPS sensor in mobile phone
High-Energy Collision of Quarks and Mesons in the Schwinger Model: From Tensor Networks to Circuit QED
With the aim of studying nonperturbative out-of-equilibrium dynamics of
high-energy particle collisions on quantum simulators, we investigate the
scattering dynamics of lattice quantum electrodynamics in 1+1 dimensions.
Working in the bosonized formulation of the model and in the thermodynamic
limit, we use uniform-matrix-product-state tensor networks to construct
multi-particle wave-packet states, evolve them in time, and detect outgoing
particles post collision. This facilitates the numerical simulation of
scattering experiments in both confined and deconfined regimes of the model at
different energies, giving rise to rich phenomenology, including inelastic
production of quark and meson states, meson disintegration, and dynamical
string formation and breaking. We obtain elastic and inelastic scattering cross
sections, together with time-resolved momentum and position distributions of
the outgoing particles. Furthermore, we propose an analog circuit-QED
implementation of the scattering process that is native to the platform,
requires minimal ingredients and approximations, and enables practical schemes
for particle wave-packet preparation and evolution. This study highlights the
role of classical and quantum simulation in enhancing our understanding of
scattering processes in quantum field theories in real time.Comment: 5+12 pages, 4+6 figures, close to published versio
Variational study of two-nucleon systems with lattice QCD
The low-energy spectrum and scattering of two-nucleon systems are studied with lattice quantum chromodynamics using a variational approach. A wide range of interpolating operators are used: dibaryon operators built from products of plane-wave nucleons, hexaquark operators built from six localized quarks, and quasilocal operators inspired by two-nucleon bound-state wave functions in low-energy effective theories. Sparsening techniques are used to compute the timeslice-to-all quark propagators required to form correlation-function matrices using products of these operators. Projection of these matrices onto irreducible representations of the cubic group, including spin-orbit coupling, is detailed. Variational methods are applied to constrain the low-energy spectra of two-nucleon systems in a single finite volume with quark masses corresponding to a pion mass of 806 MeV. Results for S- and D-wave phase shifts in the isospin singlet and triplet channels are obtained under the assumption that partial-wave mixing is negligible. Tests of interpolating-operator dependence are used to investigate the reliability of the energy spectra obtained and highlight both the strengths and weaknesses of variational methods. These studies and comparisons to previous studies using the same gauge-field ensemble demonstrate that interpolating-operator dependence can lead to significant effects on the two-nucleon energy spectra obtained using both variational and nonvariational methods, including missing energy levels and other discrepancies. While this study is inconclusive regarding the presence of two-nucleon bound states at this quark mass, it provides robust upper bounds on two-nucleon energy levels that can be improved in future calculations using additional interpolating operators and is therefore a step toward reliable nuclear spectroscopy from the underlying Standard Model of particle physics
The political identities of neighbourhood planning in England
The rise of neighbourhood planning has been characterised as another step in a remorseless de-politicisation of the public sphere. A policy initiated by the Coalition Government in England to create the conditions for local communities to support housing growth, neighbourhood planning appears to evidence a continuing retreat from political debate and contestation. Clear boundaries are established for the holistic integration of participatory democracy into the strategic plan-making of the local authority. These boundaries seek to take politics out of development decisions and exclude all issues of contention from discussion. They achieve this goal at the cost of arming participatory democracy with a collective identity around which new antagonisms may develop. Drawing on the post-political theories of Chantal Mouffe this paper identifies the return of antagonism and conflict to participation in spatial planning. Key to its argument is the concept of the boundary or frontier that in Mouffe’s theoretical framework institutionalises conflict between political entities. Drawing on primary research with neighbourhood development plans in England the paper explores how boundary conditions and boundary designations generate antagonism and necessitate political action. The paper charts the development of the collective identities that result from these boundary lines and argues for the potential for neighbourhood planning to restore political conflict to the politics of housing development
Statistical Theory for the Kardar-Parisi-Zhang Equation in 1+1 Dimension
The Kardar-Parisi-Zhang (KPZ) equation in 1+1 dimension dynamically develops
sharply connected valley structures within which the height derivative {\it is
not} continuous. There are two different regimes before and after creation of
the sharp valleys. We develop a statistical theory for the KPZ equation in 1+1
dimension driven with a random forcing which is white in time and Gaussian
correlated in space. A master equation is derived for the joint probability
density function of height difference and height gradient when the forcing correlation length is much smaller than
the system size and much bigger than the typical sharp valley width. In the
time scales before the creation of the sharp valleys we find the exact
generating function of and . Then we express the time
scale when the sharp valleys develop, in terms of the forcing characteristics.
In the stationary state, when the sharp valleys are fully developed, finite
size corrections to the scaling laws of the structure functions are also obtained.Comment: 50 Pages, 5 figure
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