9,210 research outputs found

    The derived-discrete algebras and standard equivalences

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    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

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    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 ⟨tr(FμνF~μν)⟩\langle {\rm tr} (F_{\mu\nu}\tilde F^{\mu\nu})\rangle 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

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    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

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    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

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    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 ϱ∼Tα\varrho \sim T^\alpha in a finite temperature window, and α∈[1,2)\alpha \in [1, 2) 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

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    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 E6E_{6} under modified gauge coupling unification condition at scales MXM_X in the presence of one or more dimension-5 operators. It is shown that nonsupersymmetric models of E6E_6 unification can be obtained and can easily satisfy the constraints from the proton lifetime. For constructing these models, we consider several maximal subgroups H=SO(10)×U(1),H=SU(3)×SU(3)×SU(3)H=SO(10)\times U(1), H=SU(3)\times SU(3)\times SU(3), and H=SU(2)×SU(6)H=SU(2)\times SU(6) of E6E_{6} and the usual breaking chains for a specific maximal subgroup, and derive all of the Clebsch-Gordan coefficients Φs,z(r)\Phi^{(r)}_{s,z} associated with E6E_6 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

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    The flavor changing neutral current tcV (V=\gamma,Z) couplings in the production vertex for the process e+e−→tcˉe^+e^-\to t\bar c or tˉc\bar t c 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 1.84×10−91.84 \times 10^{-9} fb at s=200GeV\sqrt s =200 GeV and 0.572×10−90.572 \times 10^{-9} fb at s=500GeV\sqrt s =500 GeV respectively. The result is much smaller than that given in ref. \cite{clwy} by a factor of 10−510^{-5}.Comment: 12 pages including 1 ps figure and 2 eps figure

    Topological Edge and Interface states at Bulk disorder-to-order Quantum Critical Points

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    We study the interplay between two nontrivial boundary effects: (1) the two dimensional (2d2d) edge states of three dimensional (3d3d) strongly interacting bosonic symmetry protected topological states, and (2) the boundary fluctuations of 3d3d bulk disorder-to-order phase transitions. We then generalize our study to 2d2d gapless states localized at an interface embedded in a 3d3d 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: (i.i.) 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; (ii.ii.) the states localized at a 2d2d interface of a 3d3d 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

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    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

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    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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