3,340 research outputs found
Geometric Scaling and QCD Dynamics in DIS
DIS data from HERA show a striking regularity as \sigma^{\gamma^* p} is a
function of the ratio \tau=Q^2/Q_s^2(x) only. The scaling function shows a
break at \tau ~ 1, which has been taken as an indication for saturation.
However, besides saturation also the transition between dominance of
k_t-ordered (DGLAP) and k_t-non-ordered (BFKL) evolution contributes to a break
around this value of \tau, as well as the suppression for small Q^2 due to
finite quark masses and confinement. In this paper we use a dipole cascade
model based on Mueller's dipole model, which also includes energy conservation
and pomeron mergins, to investigate the contributions of these different
effects to the scaling behaviour. As a result we predict that the scaling
function for \tau 1 GeV^2 become
available. We also investigate the scaling properties of the charm contribution
and the impact parameter dependence of the saturation scale.Comment: references added, figures 2, 7 and 8 updated v3: reference added,
some misprints correcte
Arnold diffusion in the dynamics of a 4-machine power system undergoing a large fault
We focus on the seemingly complicated dynamics of a four-machine power system which is undergoing a sudden fault. Adopting a Hamiltonian (energy) formulation, we consider the system as an interconnection of (one degree of freedom) subsystems. Under certain configuration (a star network) and parameter values we establish the presence of Arnold diffusion which entails periodic, almost periodic, and complicated nonperiodic dyanmics all simultaneously present; and erratic transfer of energies between the subsystems. In section 1 we introduce the transient stability problem in a mathematical setting and explain what our results mean in the power systems context. Section 2 provides insights into Arnold diffusion and summarizes its mathematical formulation as in [8], [1]. Section 3 gives conditions for which Arnold diffusion arises on certain energy levels of the swing equations. These conditions are verified analytically in the case when all but one subsystem (machine) undergo relatively small oscillations
Spectrum of D=6, N=4b Supergravity on AdS_3 x S^3
The complete spectrum of D=6, N=4b supergravity with n tensor multiplets
compactified on AdS_3 x S^3 is determined. The D=6 theory obtained from the K_3
compactification of Type IIB string requires that n=21, but we let n be
arbitrary. The superalgebra that underlies the symmetry of the resulting
supergravity theory in AdS_3 coupled to matter is SU(1,1|2)_L x SU(1,1|2)_R.
The theory also has an unbroken global SO(4)_R x SO(n) symmetry inherited from
D=6. The spectrum of states arranges itself into a tower of spin-2
supermultiplets, a tower of spin-1, SO(n) singlet supermultiplets, a tower of
spin-1 supermultiplets in the vector representation of SO(n) and a special
spin-1/2 supermultiplet also in the vector representation of SO(n). The SU(2)_L
x SU(2)_R Yang-Mills states reside in the second level of the spin-2 tower and
the lowest level of the spin-1, SO(n) singlet tower and the associated field
theory exhibits interesting properties.Comment: 37 pages, latex, 5 tables and 3 figures, typos corrected, a reference
adde
AC voltage regulation of a bidirectional high-frequency link converter using a deadbeat controller
This paper presents a digital controller for AC voltage regulation of a bidirectional high-frequency link (BHFL) inverter using Deadbeat control. The proposed controller consists of inner current loop, outer voltage loop and a feed-forward controller, which imposes a gain scheduling effect according to the reference signal to compensate the steady-state error of the system. The main property of the proposed controller is that the current- and the voltage-loop controllers have the same structure, and use the same sampling period. This simplifies the design and implementation processes. To improve the overall performance of the system, additional disturbance decoupling networks are employed. This takes into account
the model discretization effect. Therefore, accurate
disturbance decoupling can be achieved, and the system
robustness towards load variations is increased. To avoid
transformer saturation due to low frequency voltage envelopes, an equalized pulse width modulation (PWM)
technique has been introduced. The proposed controller
has been realized using the DS1104 digital signal processor
(DSP) from dSPACE. Its performances have been tested on
a one kVA prototype inverter. Experimental results showed
that the proposed controller has very fast dynamic and good
steady-state responses even under highly nonlinear loads
Vector boson mass generation without new fields
Previously a model of only vector fields with a local U(2) symmetry was
introduced for which one finds a massless U(1) photon and a massive SU(2)
vector boson in the lattice regularization. Here it is shown that quantization
of its classical continuum action leads to perturbative renormalization
difficulties. But, non-perturbative Monte Carlo calculations favor the
existence of a quantum continuum limit.Comment: 4 pages, 3 figures, 2 tables. Revised after referee reports. One
error eliminate
Komunikasi Antarbudaya Studi Negosiasi Wajah dalam Interaksi Etnik Batak dan Etnik Minang di Duri Kelurahan Gajah Sakti Kecamatan Mandau Kabupaten Bengkalis
Indonesian society is a plural society. This pluralism is made up of diverse national backgrounds in tribes, religions, races and classes. In addition to this every culture also has certain characteristics such as differences in language, customs, and habits, food and norms and values are believed. This makes the two ethnics in the city Duri ethnic Batak and ethnic Minang require to be able to adapt to different cultures. In the process of daily interaction the differences between ethnic Batak and ethnic Minang cause misunderstandings occur in everyday interactions seen from the form Facework seen from the negotiation of the face of each ethnic. This study aims to determine the forms of intercultural communication facework between ethnic batak and ethnic Minang when interacting in their daily life as well as ethnic conflict management in facial rescue to maintain their respective cultural identity in the city of Duri Kelurahan Gajah Sakti, Mandau District Bengkalis District.This research uses qualitative method with Phenomenology approach by Alfred Schutz. The location of this research is in Duri City of Gajah Sakti Village, Mandau Sub-district, Bengkalis Regency. Informants in this study amounted to ten people and determined by purposive technique. Data collection techniques used in the form of observation, interview and documentation. In achieving the validity of the data in this study, the authors use extension of participation and triangulation.The results of this study indicate that the intercultural interactions that.occur between ethnic Batak and ethnic Minang show accommodative behavior in the form of Facework through facial negotiation in the form of verbal and nonverbal when interacting in ethnic batak ethnic and ethnic Minang. Intercultural communication of ethnic Batak and ethnic Minang also experience obstacles such as cultural barriers, parangliustik, different perceptions and different nonverbal habits. These barriers are resolved through conflict managem
Diffractive Excitation in DIS and pp Collisions
We have in earlier papers presented an extension of Mueller's dipole cascade
model, which includes subleading effects from energy conservation and running
coupling as well as colour suppressed effects from pomeron loops via a ``dipole
swing''. The model was applied to describe the total cross sections in pp and
gamma*p collisions. In this paper we present a number of improvements of the
model, in particular related to the confinement mechanism. A consistent
treatment of dipole evolution and dipole--dipole interactions is achieved by
replacing the infinite range Coulomb potential by a screened potential, which
further improves the frame-independence of the model. We then apply the model
to elastic scattering and diffractive excitation, where we specifically study
the effects of different sources for fluctuations. In our formalism we can take
into account contributions from all different sources, from the dipole cascade
evolution, the dipole--dipole scattering, from the impact-parameter dependence,
and from the initial photon and proton wavefunctions. Good agreement is
obtained with data from the Tevatron and from HERA, and we also present some
predictions for the LHC.Comment: correction of titl
A hadron model with breaking of spatial homogeneity of vacuum
A possible breaking of spatial homogeneity of vacuum due to the interaction
between quark and Bose-field is analyzed. It is shown that in this case quark
can be in a localized state (like wave packet). Energetic conditions for such a
spontaneous symmetry breaking are found in suggested model. Possible
consequences of such symmetry breaking, in particular, the origin of deep
inelastic processes and quark confinement phenomenon are discussed.Comment: 4 page
Gauged D=7 Supergravity on the S**1/Z_2 Orbifold
We construct the most general couplings of a bulk seven-dimensional
Yang-Mills-Einstein N=2 supergravity with a boundary six-dimensional chiral
N=(0,1) theory of vectors and charged hypermultiplets. The boundary consists of
two brane worlds sitting at the fixed points of an S^1/Z_2 compactification of
the seven-dimensional bulk supergravity. The resulting 6D massless spectrum
surviving the orbifold projection is anomalous. By introducing boundary fields
at the orbifold fixed points, we show that all anomalies are cancelled by a
Green-Schwarz mechanism. In addition, all couplings of the boundary fields to
the bulk are completely specified by supersymmetry. We emphasize that there is
no bulk Chern-Simons term to cancel the anomalies. The latter is traded for a
Green-Schwarz term which emerges in the boundary theory after a duality
transformation implemented to construct the bulk supergravity.Comment: LaTeX, 42 pages; typos corrected, reference added, version to appear
in Phys. Rev.
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