9,210 research outputs found
The derived-discrete algebras and standard equivalences
We prove that any derived equivalence between derived-discrete algebras of
finite global dimension is standard, that is, isomorphic to the derived tensor
functor by a two-sided tilting complex.Comment: 19 page
Baryons in the Sakai-Sugimoto model in the D0-D4 background
The baryon spectrum in the Sakai-Sugimoto model in the D4 background with
smeared D0 charges is studied. We follow the instanton description of baryons
by Hata et al.[Prog. Theor. Phys. 117, 1157]. The background corresponds to an
excited state with nonzero glue condensate which is proportional to the D0 charge density. The baryon
size shrinks when we turn on small D0 charge density. But for larger D0 charge
density where massive modes in the gauge theory may also take effect, the size
of baryons will grow. The difference between baryon masses will become smaller
when D0 charge density increases. There may also be indications that the baryon
will become unstable and cannot exist for sufficiently large D0 density.Comment: 15 pages, 3 figure
Galaxy Learning -- A Position Paper
The recent rapid development of artificial intelligence (AI, mainly driven by
machine learning research, especially deep learning) has achieved phenomenal
success in various applications. However, to further apply AI technologies in
real-world context, several significant issues regarding the AI ecosystem
should be addressed. We identify the main issues as data privacy, ownership,
and exchange, which are difficult to be solved with the current centralized
paradigm of machine learning training methodology. As a result, we propose a
novel model training paradigm based on blockchain, named Galaxy Learning, which
aims to train a model with distributed data and to reserve the data ownership
for their owners. In this new paradigm, encrypted models are moved around
instead, and are federated once trained. Model training, as well as the
communication, is achieved with blockchain and its smart contracts. Pricing of
training data is determined by its contribution, and therefore it is not about
the exchange of data ownership. In this position paper, we describe the
motivation, paradigm, design, and challenges as well as opportunities of Galaxy
Learning
Distinguishing the right-handed up/charm quarks from top quark via discrete symmetries in the standard model extensions
We propose a class of the two Higgs doublet Standard models (SMs) with a SM
singlet and a class of supersymmetric SMs with two pairs of Higgs doublets,
where the right-handed up/charm quarks and the right-handed top quark have
different quantum numbers under extra discrete symmetries. Thus, the
right-handed up and charm quarks couple to one Higgs doublet field, while the
right-handed top quark couples to another Higgs doublet. The quark CKM mixings
can be generated from the down-type quark sector. As one of phenomenological
consequences in our models, we explore whether one can accommodate the observed
direct CP asymmetry difference in singly Cabibbo-suppressed D decays. We show
that it is possible to explain the measured values of CP violation under
relevant experimental constraints.Comment: 20 pages; matches published versio
Lattice models for Non-Fermi Liquids with Tunable Transport Scalings
A variety of exotic non-fermi liquid (NFL) states have been observed in many
condensed matter systems, with different scaling relations between transport
coefficients and temperature. The "standard" approach to studying these NFLs is
by coupling a Fermi liquid to quantum critical fluctuations, which potentially
can drive the system into a NFL. In this work we seek for an alternative
understanding of these various NFLs in a unified framework. We first construct
two "elementary" randomness-free models with four-fermion interactions only,
whose many properties can be analyzed exactly in certain limit just like the
Sachdev-Ye-Kitaev (SYK) model. The most important new feature of our models is
that, the fermion scaling dimension in the conformal invariant solution in the
infrared limit is tunable by charge density. Then based on these elementary
models, we propose two versions of lattice models with four fermion
interactions which give us non-fermi liquid behaviors with DC resistivity
scaling in a finite temperature window, and depends on the fermion density in the model, which is a rather
universal feature observed in many experimental systems.Comment: 13 pages, 2 figure
E6 GUT through Effects of Dimension-5 Operators
In the effective field theory framework, quantum gravity can induce effective
dimension-5 operators, which have important impacts on grand unified theories.
Interestingly, one of main effects is the modification of the usual gauge
coupling unification condition. We investigate the gauge coupling unification
in under modified gauge coupling unification condition at scales
in the presence of one or more dimension-5 operators. It is shown that
nonsupersymmetric models of unification can be obtained and can easily
satisfy the constraints from the proton lifetime. For constructing these
models, we consider several maximal subgroups , and of and the
usual breaking chains for a specific maximal subgroup, and derive all of the
Clebsch-Gordan coefficients associated with breaking
to the Standard Model, which are given in Appendix A.Comment: 20 pages, 10 tables, 8 figures, journal accepted versio
Top-Charm Associated Production at High Energy e^+e^- Colliders in Standard Model
The flavor changing neutral current tcV (V=\gamma,Z) couplings in the
production vertex for the process or in the
standard model are investigated. The precise calculations keeping all quark
masses non-zero are carried out. The total production cross section is found to
be fb at and fb
at respectively. The result is much smaller than that given
in ref. \cite{clwy} by a factor of .Comment: 12 pages including 1 ps figure and 2 eps figure
Topological Edge and Interface states at Bulk disorder-to-order Quantum Critical Points
We study the interplay between two nontrivial boundary effects: (1) the two
dimensional () edge states of three dimensional () strongly interacting
bosonic symmetry protected topological states, and (2) the boundary
fluctuations of bulk disorder-to-order phase transitions. We then
generalize our study to gapless states localized at an interface embedded
in a bulk, when the bulk undergoes a quantum phase transition. Our study
is based on generic long wavelength descriptions of these systems and
controlled analytic calculations. Our results are summarized as follows: ()
The edge state of a prototype bosonic symmetry protected states can be driven
to a new fixed point by coupling to the boundary fluctuations of a bulk quantum
phase transition; () the states localized at a interface of a
SU(N) quantum antiferromagnet may be driven to a new fixed point by coupling to
the bulk quantum critical modes. Properties of the new fixed points identified
are also studied.Comment: 8 pages, 7 figure
Linear Precoding for the MIMO Multiple Access Channel with Finite Alphabet Inputs and Statistical CSI
In this paper, we investigate the design of linear precoders for the
multiple-input multiple-output (MIMO) multiple access channel (MAC). We assume
that statistical channel state information (CSI) is available at the
transmitters and consider the problem under the practical finite alphabet input
assumption. First, we derive an asymptotic (in the large system limit)
expression for the weighted sum rate (WSR) of the MIMO MAC with finite alphabet
inputs and Weichselberger's MIMO channel model. Subsequently, we obtain the
optimal structures of the linear precoders of the users maximizing the
asymptotic WSR and an iterative algorithm for determining the precoders. We
show that the complexity of the proposed precoder design is significantly lower
than that of MIMO MAC precoders designed for finite alphabet inputs and
instantaneous CSI. Simulation results for finite alphabet signalling indicate
that the proposed precoder achieves significant performance gains over existing
precoder designs.Comment: Accepted by IEEE Transactions on Wireless Communications. arXiv admin
note: substantial text overlap with arXiv:1401.540
The Petrov-like boundary condition at finite cutoff surface in Gravity/Fluid duality
Previously it has been shown that imposing a Petrov-like boundary condition
on a hypersurface may reduce the Einstein equation to the incompressible
Navier-Stokes equation, but all these correspondences are established in the
near horizon limit. In this note, we remark that this strategy can be extended
to an arbitrary finite cutoff surface which is spatially flat, and the
Navier-Stokes equation is obtained by employing a non-relativistic
long-wavelength limit.Comment: 17 pages, no figures, published in PR
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