The Color Antisymmetric Ghost Propagator and One-Loop Vertex Renormalization
Furui, Sadataka
2007-01-01
The color matrix elements of the ghost triangle diagram that appears in the triple gluon vertex and the ghost-ghost-gluon triangle diagram that appears in the ghost-gluon-ghost vertex are calculated. The ghost-ghost-gluon triangle contains a loop consisting of two color diagonal ghosts and one gluon and a loop consisting of two color antisymmetric ghosts and one gluon. Consequently, the pQCD argument in the infrared region based on the one particle irreducible diagram should be modified. Impl...
Tazai, Rina; Yamakawa, Youichi; Tsuchiizu, Masahisa; Kontani, Hiroshi
2016-09-01
In various multiorbital systems, the emergence of the orbital fluctuations and their role on the pairing mechanism attract increasing attention. To achieve deep understanding on these issues, we perform a functional renormalization group (fRG) study for the two-orbital Hubbard model. The vertex corrections for the electron-boson coupling (U -VC), which are dropped in the Migdal-Eliashberg gap equation, are obtained by solving the RG equation. We reveal that the dressed electron-boson coupling for the charge channel Ûeffc becomes much larger than the bare Coulomb interaction Û 0 due to the U -VC in the presence of moderate spin fluctuations. For this reason, the attractive pairing interaction due to the charge or orbital fluctuations is enlarged by the factor (Ûeffc/Û0) 2≫1 . In contrast, the spin fluctuation pairing interaction is suppressed by the spin-channel U -VC, because of the relation Ûeffs≪Û 0 . The present study demonstrates that the orbital or charge fluctuation pairing mechanism can be realized in various multiorbital systems thanks to the U -VC, such as in Fe-based superconductors.
Renormalization: an advanced overview
Gurau, R.; Rivasseau, V.; Sfondrini, A.|info:eu-repo/dai/nl/330983083
2014-01-01
We present several approaches to renormalization in QFT: the multi-scale analysis in perturbative renormalization, the functional methods \\`a la Wetterich equation, and the loop-vertex expansion in non-perturbative renormalization. While each of these is quite well-established, they go beyond
Renormalization: an advanced overview
Gurau, Razvan; Sfondrini, Alessandro
2014-01-01
We present several approaches to renormalization in QFT: the multi-scale analysis in perturbative renormalization, the functional methods \\`a la Wetterich equation, and the loop-vertex expansion in non-perturbative renormalization. While each of these is quite well-established, they go beyond standard QFT textbook material, and may be little-known to specialists of each other approach. This review is aimed at bridging this gap.
Blossier, Benoît; Guichon, Pierre; Morénas, Vincent; Pène, Olivier; Rodríguez-Quintero, Jose; Zafeiropoulos, Savvas
2014-01-01
We present a precise non-perturbative determination of the renormalization constants in the mass independent RI'-MOM scheme. The lattice implementation uses the Iwasaki gauge action and four degenerate dynamical twisted mass fermions. The gauge configurations are provided by the ETM Collaboration. Renormalization constants for scalar, pseudo-scalar, vector and axial operators, as well as the quark propagator renormalization, are computed at three different values of the lattice spacing, two volumes and several twisted mass parameters. The method we developed allows for a precise cross-check of the running, thanks to the particular proper treatment of hypercubic artifacts. Results for the twist-2 operator $O_{44}$ are also presented.
Renormalization group approach to superfluid neutron matter
Energy Technology Data Exchange (ETDEWEB)
Hebeler, K.
2007-06-06
In the present thesis superfluid many-fermion systems are investigated in the framework of the Renormalization Group (RG). Starting from an experimentally determined two-body interaction this scheme provides a microscopic approach to strongly correlated many-body systems at low temperatures. The fundamental objects under investigation are the two-point and the four-point vertex functions. We show that explicit results for simple separable interactions on BCS-level can be reproduced in the RG framework to high accuracy. Furthermore the RG approach can immediately be applied to general realistic interaction models. In particular, we show how the complexity of the many-body problem can be reduced systematically by combining different RG schemes. Apart from technical convenience the RG framework has conceptual advantage that correlations beyond the BCS level can be incorporated in the flow equations in a systematic way. In this case however the flow equations are no more explicit equations like at BCS level but instead a coupled set of implicit equations. We show on the basis of explicit calculations for the single-channel case the efficacy of an iterative approach to this system. The generalization of this strategy provides a promising strategy for a non-perturbative treatment of the coupled channel problem. By the coupling of the flow equations of the two-point and four-point vertex self-consistency on the one-body level is guaranteed at every cutoff scale. (orig.)
Four-Point Wavelets and Their Applications
Institute of Scientific and Technical Information of China (English)
魏国富; 陈发来
2002-01-01
Multiresolution analysis (MRA) and wavelets provide useful and efficient tools for representing functions at multiple levels of details. Wavelet representations have been used in a broad range of applications, including image compression, physical simulation and numerical analysis. In this paper, the authors construct a new class of wavelets, called four-point wavelets,based on an interpolatory four-point subdivision scheme. They are of local support, symmetric and stable. The analysis and synthesis algorithms have linear time complexity. Depending on different weight parameters w, the scaling functions and wavelets generated by the four-point subdivision scheme are of different degrees of smoothness. Therefore the user can select better wavelets relevant to the practice among the classes of wavelets. The authors apply the fourpoint wavelets in signal compression. The results show that the four-point wavelets behave much better than B-spline wavelets in many situations.
Renormalization conditions and non-diagrammatic approach to renormalizations
Faizullaev, B. A.; Garnov, S. A.
1996-01-01
The representation of the bare parameters of Lagrangian in terms of total vertex Green's functions is used to obtain the general form of renormalization conditions. In the framework of this approach renormalizations can be carried out without treatment to Feynman diagrams.
Scanning microscopic four-point conductivity probes
DEFF Research Database (Denmark)
Petersen, Christian Leth; Hansen, Torben Mikael; Bøggild, Peter
2002-01-01
A method for fabricating microscopic four-point probes is presented. The method uses silicon-based microfabrication technology involving only two patterning steps. The last step in the fabrication process is an unmasked deposition of the conducting probe material, and it is thus possible to select...... the conducting material either for a silicon wafer or a single probe unit. Using shadow masking photolithography an electrode spacing (pitch) down to 1.1 mum was obtained, with cantilever separation down to 200 run. Characterisation measurements have shown the microscopic probes to be mechanically very flexible...
Renormalized Cosmological Perturbation Theory
Crocce, M
2006-01-01
We develop a new formalism to study nonlinear evolution in the growth of large-scale structure, by following the dynamics of gravitational clustering as it builds up in time. This approach is conveniently represented by Feynman diagrams constructed in terms of three objects: the initial conditions (e.g. perturbation spectrum), the vertex (describing non-linearities) and the propagator (describing linear evolution). We show that loop corrections to the linear power spectrum organize themselves into two classes of diagrams: one corresponding to mode-coupling effects, the other to a renormalization of the propagator. Resummation of the latter gives rise to a quantity that measures the memory of perturbations to initial conditions as a function of scale. As a result of this, we show that a well-defined (renormalized) perturbation theory follows, in the sense that each term in the remaining mode-coupling series dominates at some characteristic scale and is subdominant otherwise. This is unlike standard perturbatio...
Fundamental size limitations of micro four-point probes
DEFF Research Database (Denmark)
Ansbæk, Thor; Petersen, Dirch Hjorth; Hansen, Ole
2009-01-01
-scaled as well in order to correctly characterize the extremely thin films used. This presents a four-point probe design and fabrication challenge. We analyze the fundamental limitation on down-scaling of a generic micro four-point probe (M4PP) in a comprehensive study, where mechanical, thermal, and electrical...
Four point bending setup for characterization of semiconductor piezoresistance
DEFF Research Database (Denmark)
Richter, Jacob; Arnoldus, Morten Berg; Hansen, Ole
2008-01-01
We present a four point bending setup suitable for high precision characterization of piezoresistance in semiconductors. The compact setup has a total size of 635 cm3. Thermal stability is ensured by an aluminum housing wherein the actual four point bending fixture is located. The four point...... bending fixture is manufactured in polyetheretherketon and a dedicated silicon chip with embedded piezoresistors fits in the fixture. The fixture is actuated by a microstepper actuator and a high sensitivity force sensor measures the applied force on the fixture and chip. The setup includes heaters...
Tessellating cushions: four-point functions in N=4 SYM
Eden, Burkhard
2016-01-01
We consider a class of planar tree-level four-point functions in N=4 SYM in a special kinematic regime: one BMN operator with two scalar excitations and three half-BPS operators are put onto a line in configuration space; additionally, for the half-BPS operators a co-moving frame is chosen in flavour space. In configuration space, the four-punctured sphere is naturally triangulated by tree-level planar diagrams. We demonstrate on a number of examples that each tile can be associated with a modified hexagon form-factor in such a way as to efficiently reproduce the tree-level four-point function. Our tessellation is not of the OPE type, fostering the hope of finding an independent, integrability-based approach to the computation of planar four-point functions.
A laboratory on the four-point probe technique
Schuetze, Andrew P.; Lewis, Wayne; Brown, Chris; Geerts, Wilhelmus J.
2004-02-01
We describe how a classic electrostatics experiment can be modified to be a four-point probe lab experiment. Students use the four-point probe technique to investigate how the measured resistance varies as a function of the position of the electrodes with respect to the edge of the sample. By using elementary electromagnetism concepts such as the superposition principle, the continuity equation, the relation between electric field and electric potential, and Ohm's law, a simple model is derived to describe the four-point probe technique. Although the lab introduces the students to the ideas behind the Laplace equation and the methods of images, advanced mathematics is avoided so that the experiment can be done in trigonometry and algebra based physics courses. In addition, the experiment introduces the students to a standard measurement technique that is widely used in industry and thus provides them with useful hands-on experience.
Four-point function in the IOP matrix model
Michel, Ben; Polchinski, Joseph; Rosenhaus, Vladimir; Suh, S. Josephine
2016-05-01
The IOP model is a quantum mechanical system of a large- N matrix oscillator and a fundamental oscillator, coupled through a quartic interaction. It was introduced previously as a toy model of the gauge dual of an AdS black hole, and captures a key property that at infinite N the two-point function decays to zero on long time scales. Motivated by recent work on quantum chaos, we sum all planar Feynman diagrams contributing to the four-point function. We find that the IOP model does not satisfy the more refined criteria of exponential growth of the out-of-time-order four-point function.
Junction leakage measurements with micro four-point probes
DEFF Research Database (Denmark)
Lin, Rong; Petersen, Dirch Hjorth; Wang, Fei;
2012-01-01
We present a new, preparation-free method for measuring the leakage current density on ultra-shallow junctions. The junction leakage is found by making a series of four-point sheet resistance measurements on blanket wafers with variable electrode spacings. The leakage current density is calculated...... using a fit of the measured four-point resistances to an analytical two-sheet model. The validity of the approximation involved in the two-sheet model is verified by a comparison to finite element model calculations....
Four-point function in the IOP matrix model
Michel, Ben; Rosenhaus, Vladimir; Suh, S Josephine
2016-01-01
The IOP model is a quantum mechanical system of a large-$N$ matrix oscillator and a fundamental oscillator, coupled through a quartic interaction. It was introduced previously as a toy model of the gauge dual of an AdS black hole, and captures a key property that at infinite $N$ the two-point function decays to zero on long time scales. Motivated by recent work on quantum chaos, we sum all planar Feynman diagrams contributing to the four-point function. We find that the IOP model does not satisfy the more refined criteria of exponential growth of the out-of-time-order four-point function.
Complete renormalization of QCD at five loops
Luthe, Thomas; Maier, Andreas; Marquard, Peter; Schröder, York
2017-03-01
We present new analytical five-loop Feynman-gauge results for the anomalous dimensions of ghost field and -vertex, generalizing the known values for SU(3) to a general gauge group. Together with previously published results on the quark mass and -field anomalous dimensions and the Beta function, this completes the 5-loop renormalization program of gauge theories in that gauge.
Junction leakage measurements with micro four-point probes
DEFF Research Database (Denmark)
Lin, Rong; Petersen, Dirch Hjorth; Wang, Fei
2012-01-01
We present a new, preparation-free method for measuring the leakage current density on ultra-shallow junctions. The junction leakage is found by making a series of four-point sheet resistance measurements on blanket wafers with variable electrode spacings. The leakage current density is calculate...
Chabanat, E; D'Hondt, J; Vanlaer, P; Prokofiev, K; Speer, T; Frühwirth, R; Waltenberger, W
2005-01-01
Because of the high track multiplicity in the final states expected in proton collisions at the LHC experiments, novel vertex reconstruction algorithms are required. The vertex reconstruction problem can be decomposed into a pattern recognition problem ("vertex finding") and an estimation problem ("vertex fitting"). Starting from least-square methods, ways to render the classical algorithms more robust are discussed and the statistical properties of the novel methods are shown. A whole set of different approaches for the vertex finding problem is presented and compared in relevant physics channels.
Micro-four-point Probe Hall effect Measurement method
DEFF Research Database (Denmark)
Petersen, Dirch Hjorth; Hansen, Ole; Lin, Rong
2008-01-01
barriers and with a magnetic field applied normal to the plane of the sheet. Based on this potential, analytical expressions for the measured four-point resistance in presence of a magnetic field are derived for several simple sample geometries. We show how the sheet resistance and Hall effect......We report a new microscale Hall effect measurement method for characterization of semiconductor thin films without need for conventional Hall effect geometries and metal contact pads. We derive the electrostatic potential resulting from current flow in a conductive filamentary sheet with insulating...... contributions may be separated using dual configuration measurements. The method differs from conventional van der Pauw measurements since the probe pins are placed in the interior of the sample region, not just on the perimeter. We experimentally verify the method by micro-four-point probe measurements...
Functional renormalization for antiferromagnetism and superconductivity in the Hubbard model
Energy Technology Data Exchange (ETDEWEB)
Friederich, Simon
2010-12-08
Despite its apparent simplicity, the two-dimensional Hubbard model for locally interacting fermions on a square lattice is widely considered as a promising approach for the understanding of Cooper pair formation in the quasi two-dimensional high-T{sub c} cuprate materials. In the present work this model is investigated by means of the functional renormalization group, based on an exact flow equation for the effective average action. In addition to the fermionic degrees of freedom of the Hubbard Hamiltonian, bosonic fields are introduced which correspond to the different possible collective orders of the system, for example magnetism and superconductivity. The interactions between bosons and fermions are determined by means of the method of ''rebosonization'' (or ''flowing bosonization''), which can be described as a continuous, scale-dependent Hubbard-Stratonovich transformation. This method allows an efficient parameterization of the momentum-dependent effective two-particle interaction between fermions (four-point vertex), and it makes it possible to follow the flow of the running couplings into the regimes exhibiting spontaneous symmetry breaking, where bosonic fluctuations determine the types of order which are present on large length scales. Numerical results for the phase diagram are presented, which include the mutual influence of different, competing types of order. (orig.)
Magic identities for conformal four-point integrals
Drummond, J M; Smirnov, V A; Sokatchev, E S
2007-01-01
We propose an iterative procedure for constructing classes of off-shell four-point conformal integrals which are identical. The proof of the identity is based on the conformal properties of a subintegral common for the whole class. The simplest example are the so-called `triple scalar box' and `tennis court' integrals. In this case we also give an independent proof using the method of Mellin--Barnes representation which can be applied in a similar way for general off-shell Feynman integrals.
Chen, Li; Shen, Cencheng; Vogelstein, Joshua; Priebe, Carey
2013-01-01
For random graphs distributed according to stochastic blockmodels, a special case of latent position graphs, adjacency spectral embedding followed by appropriate vertex classification is asymptotically Bayes optimal; but this approach requires knowledge of and critically depends on the model dimension. In this paper, we propose a sparse representation vertex classifier which does not require information about the model dimension. This classifier represents a test vertex as a sparse combinatio...
Lavrov, P. M.; Shapiro, I. L.
2012-09-01
We consider the renormalization of general gauge theories on curved space-time background, with the main assumption being the existence of a gauge-invariant and diffeomorphism invariant regularization. Using the Batalin-Vilkovisky (BV) formalism one can show that the theory possesses gauge invariant and diffeomorphism invariant renormalizability at quantum level, up to an arbitrary order of the loop expansion.
Open-Source Automated Mapping Four-Point Probe
Directory of Open Access Journals (Sweden)
Handy Chandra
2017-01-01
Full Text Available Scientists have begun using self-replicating rapid prototyper (RepRap 3-D printers to manufacture open source digital designs of scientific equipment. This approach is refined here to develop a novel instrument capable of performing automated large-area four-point probe measurements. The designs for conversion of a RepRap 3-D printer to a 2-D open source four-point probe (OS4PP measurement device are detailed for the mechanical and electrical systems. Free and open source software and firmware are developed to operate the tool. The OS4PP was validated against a wide range of discrete resistors and indium tin oxide (ITO samples of different thicknesses both pre- and post-annealing. The OS4PP was then compared to two commercial proprietary systems. Results of resistors from 10 to 1 MΩ show errors of less than 1% for the OS4PP. The 3-D mapping of sheet resistance of ITO samples successfully demonstrated the automated capability to measure non-uniformities in large-area samples. The results indicate that all measured values are within the same order of magnitude when compared to two proprietary measurement systems. In conclusion, the OS4PP system, which costs less than 70% of manual proprietary systems, is comparable electrically while offering automated 100 micron positional accuracy for measuring sheet resistance over larger areas.
Open-Source Automated Mapping Four-Point Probe.
Chandra, Handy; Allen, Spencer W; Oberloier, Shane W; Bihari, Nupur; Gwamuri, Jephias; Pearce, Joshua M
2017-01-26
Scientists have begun using self-replicating rapid prototyper (RepRap) 3-D printers to manufacture open source digital designs of scientific equipment. This approach is refined here to develop a novel instrument capable of performing automated large-area four-point probe measurements. The designs for conversion of a RepRap 3-D printer to a 2-D open source four-point probe (OS4PP) measurement device are detailed for the mechanical and electrical systems. Free and open source software and firmware are developed to operate the tool. The OS4PP was validated against a wide range of discrete resistors and indium tin oxide (ITO) samples of different thicknesses both pre- and post-annealing. The OS4PP was then compared to two commercial proprietary systems. Results of resistors from 10 to 1 MΩ show errors of less than 1% for the OS4PP. The 3-D mapping of sheet resistance of ITO samples successfully demonstrated the automated capability to measure non-uniformities in large-area samples. The results indicate that all measured values are within the same order of magnitude when compared to two proprietary measurement systems. In conclusion, the OS4PP system, which costs less than 70% of manual proprietary systems, is comparable electrically while offering automated 100 micron positional accuracy for measuring sheet resistance over larger areas.
Face pose tracking using the four-point algorithm
Fung, Ho Yin; Wong, Kin Hong; Yu, Ying Kin; Tsui, Kwan Pang; Kam, Ho Chuen
2017-06-01
In this paper, we have developed an algorithm to track the pose of a human face robustly and efficiently. Face pose estimation is very useful in many applications such as building virtual reality systems and creating an alternative input method for the disabled. Firstly, we have modified a face detection toolbox called DLib for the detection of a face in front of a camera. The detected face features are passed to a pose estimation method, known as the four-point algorithm, for pose computation. The theory applied and the technical problems encountered during system development are discussed in the paper. It is demonstrated that the system is able to track the pose of a face in real time using a consumer grade laptop computer.
Lecture Notes on Holographic Renormalization
Skenderis, K
2002-01-01
We review the formalism of holographic renormalization. We start by discussing mathematical results on asymptotically anti-de Sitter spacetimes. We then outline the general method of holographic renormalization. The method is illustrated by working all details in a simple example: a massive scalar field on anti-de Sitter spacetime. The discussion includes the derivation of the on-shell renormalized action, of holographic Ward identities, anomalies and RG equations, and the computation of renormalized one-, two- and four-point functions. We then discuss the application of the method to holographic RG flows. We also show that the results of the near-boundary analysis of asymptotically AdS spacetimes can be analytically continued to apply to asymptotically de Sitter spacetimes. In particular, it is shown that the Brown-York stress energy tensor of de Sitter spacetime is equal, up to a dimension dependent sign, to the Brown-York stress energy tensor of an associated AdS spacetime.
Stiffness identification of four-point-elastic-support rigid plate
Institute of Scientific and Technical Information of China (English)
彭利平; 刘初升; 武继达; 王帅
2015-01-01
As the stiffness of the elastic support varies with the physical-chemical erosion and mechanical friction, model catastrophe of a single degree-of-freedom (DOF) isolation system may occur. A 3-DOF four-point-elastic-support rigid plate (FERP) structure is presented to describe the catastrophic isolation system. Based on the newly-established structure, theoretical derivation for stiffness matrix calculation by free response (SMCbyFR) and the method of stiffness identification by stiffness matrix disassembly (SIbySMD) are proposed. By integrating the SMCbyFR and the SIbySMD and defining the stiffness assurance criterion (SAC), the procedures for stiffness identification of a FERP structure (SIFERP) are summarized. Then, a numerical example is adopted for the SIFERP validation, in which the simulated tested free response data are generated by the numerical methods, and operation for filtering noise is conducted to imitate the practical application. Results in the numerical example demonstrate the feasibility and accuracy of the developed SIFERP for stiffness identification.
Wermes, Norbert
2006-01-01
Pixel vertex detectors are THE instrument of choice for the tracking of charged particles close to the interaction point at the LHC. Hybrid pixel detectors, in which sensor and read-out IC are separate entities, constitute the present state of the art in detector technology. Three of the LHC detectors use vertex detectors based on this technology. A development period of almost 10 years has resulted in pixel detector modules which can stand the extreme rate and timing requirements as well as ...
Duka, P; Zralek, M
2000-01-01
Quantization and renormalization of the left-right symmetric model is the main purpose of the paper. First the model at tree level with a Higgs sector containing one bidoublet and two triplets is precisely discussed. Then the canonical quantization and Faddeev-Popov Lagrangian are carried out ('t Hooft gauge). The BRST symmetry is discussed. Subsequently the on mass shell renormalization is performed and, as a test of consistency, the renormalization of the ZNiNj vertex is analyzed.
Renormalization Scheme Dependence and Renormalization Group Summation
McKeon, D G C
2016-01-01
We consider logarithmic contributions to the free energy, instanton effective action and Laplace sum rules in QCD that are a consequence of radiative corrections. Upon summing these contributions by using the renormalization group, all dependence on the renormalization scale parameter mu cancels. The renormalization scheme dependence in these processes is examined, and a renormalization scheme is found in which the effect of higher order radiative corrections is absorbed by the behaviour of the running coupling.
Cluster functional renormalization group
Reuther, Johannes; Thomale, Ronny
2014-01-01
Functional renormalization group (FRG) has become a diverse and powerful tool to derive effective low-energy scattering vertices of interacting many-body systems. Starting from a free expansion point of the action, the flow of the RG parameter Λ allows us to trace the evolution of the effective one- and two-particle vertices towards low energies by taking into account the vertex corrections between all parquet channels in an unbiased fashion. In this work, we generalize the expansion point at which the diagrammatic resummation procedure is initiated from a free UV limit to a cluster product state. We formulate a cluster FRG scheme where the noninteracting building blocks (i.e., decoupled spin clusters) are treated exactly, and the intercluster couplings are addressed via RG. As a benchmark study, we apply our cluster FRG scheme to the spin-1/2 bilayer Heisenberg model (BHM) on a square lattice where the neighboring sites in the two layers form the individual two-site clusters. Comparing with existing numerical evidence for the BHM, we obtain reasonable findings for the spin susceptibility, the spin-triplet excitation energy, and quasiparticle weight even in coupling regimes close to antiferromagnetic order. The concept of cluster FRG promises applications to a large class of interacting electron systems.
String loop corrections from fusion of handles and vertex operators
Ooguri, H.; Sakai, N.
1987-10-01
Handle operators are introduced to describe nonlinear sigma models on higher genus surfaces by an operator formalism. Operator product expansions (fusions) among handle and vertex operators provide new sources of conformal symmetry breakings. Through the renormalization group equations, string-loop corrected equations of motion without one-particle reducible parts are derived to one-loop order. Work supported in part by Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture (No. 61540200).
Gover, A Rod
2016-01-01
For any conformally compact manifold with hypersurface boundary we define a canonical renormalized volume functional and compute an explicit, holographic formula for the corresponding anomaly. For the special case of asymptotically Einstein manifolds, our method recovers the known results. The anomaly does not depend on any particular choice of regulator, but the coefficients of divergences do. We give explicit formulae for these divergences valid for any choice of regulating hypersurface; these should be relevant to recent studies of quantum corrections to entanglement entropies. The anomaly is expressed as a conformally invariant integral of a local Q-curvature that generalizes the Branson Q-curvature by including data of the embedding. In each dimension this canonically defines a higher dimensional generalization of the Willmore energy/rigid string action. We show that the variation of these energy functionals is exactly the obstruction to solving a singular Yamabe type problem with boundary data along the...
Vidal, G
2007-11-30
We propose a real-space renormalization group (RG) transformation for quantum systems on a D-dimensional lattice. The transformation partially disentangles a block of sites before coarse-graining it into an effective site. Numerical simulations with the ground state of a 1D lattice at criticality show that the resulting coarse-grained sites require a Hilbert space dimension that does not grow with successive RG transformations. As a result we can address, in a quasi-exact way, tens of thousands of quantum spins with a computational effort that scales logarithmically in the system's size. The calculations unveil that ground state entanglement in extended quantum systems is organized in layers corresponding to different length scales. At a quantum critical point, each relevant length scale makes an equivalent contribution to the entanglement of a block.
The Orbifold Topological Vertex
Bryan, Jim; Young, Ben
2010-01-01
We define Donaldson-Thomas invariants of Calabi-Yau orbifolds and we develop a topological vertex formalism for computing them. The basic combinatorial object is the orbifold vertex, a generating function for the number of 3D partitions asymptotic to three given 2D partitions and colored by representations of a finite Abelian group G acting on C^3. In the case where G=Z_n acting on C^3 with transverse A_{n-1} quotient singularities, we give an explicit formula for the vertex in terms of Schur functions. We discuss applications of our formalism to the Donaldson-Thomas Crepant Resolution Conjecture and to the orbifold Donaldson-Thomas/Gromov-Witten correspondence. We also explicitly compute the Donaldson-Thomas partition function for some simple orbifold geometries: the local football and the local BZ_2 gerbe.
Improved Epstein–Glaser renormalization in x-space versus differential renormalization
Energy Technology Data Exchange (ETDEWEB)
Gracia-Bondía, José M. [Department of Theoretical Physics, Universidad de Zaragoza, 50009 Zaragoza (Spain); BIFI Research Center, Universidad de Zaragoza, 50018 Zaragoza (Spain); Department of Physics, Universidad de Costa Rica, San José 11501 (Costa Rica); Gutiérrez, Heidy [Department of Physics, Universidad de Costa Rica, San José 11501 (Costa Rica); Várilly, Joseph C., E-mail: joseph.varilly@ucr.ac.cr [Department of Mathematics, Universidad de Costa Rica, San José 11501 (Costa Rica)
2014-09-15
Renormalization of massless Feynman amplitudes in x-space is reexamined here, using almost exclusively real-variable methods. We compute a wealth of concrete examples by means of recursive extension of distributions. This allows us to show perturbative expansions for the four-point and two-point functions at several loop order. To deal with internal vertices, we expound and expand on convolution theory for log-homogeneous distributions. The approach has much in common with differential renormalization as given by Freedman, Johnson and Latorre; but differs in important details.
Improved Epstein–Glaser renormalization in x-space versus differential renormalization
Directory of Open Access Journals (Sweden)
José M. Gracia-Bondía
2014-09-01
Full Text Available Renormalization of massless Feynman amplitudes in x-space is reexamined here, using almost exclusively real-variable methods. We compute a wealth of concrete examples by means of recursive extension of distributions. This allows us to show perturbative expansions for the four-point and two-point functions at several loop order. To deal with internal vertices, we expound and expand on convolution theory for log-homogeneous distributions. The approach has much in common with differential renormalization as given by Freedman, Johnson and Latorre; but differs in important details.
Hague, J P
2003-01-01
I apply the newly developed dynamical cluster approximation (DCA) to the calculation of the electron and phonon dispersions in the two-dimensional Holstein model. In contrast to previous work, the DCA enables the effects of spatial fluctuations (non-local corrections) to be examined. Approximations neglecting and incorporating lowest-order vertex corrections are investigated. I calculate the phonon density of states, the renormalized phonon dispersion, the electron dispersion and electron spectral functions. I demonstrate how vertex corrections stabilize the solution, stopping a catastrophic softening of the (pi, pi) phonon mode. A kink in the electron dispersion is found in the normal state along the (zeta, zeta) symmetry direction in both the vertex- and non-vertex-corrected theories for low phonon frequencies, corresponding directly to the renormalized phonon frequency at the (pi, 0) point. This kink is accompanied by a sudden drop in the quasi-particle lifetime. Vertex and non-local corrections enhance th...
Cohomological vertex operators
Viña, Andrés
2016-01-01
Given a Calabi-Yau manifold and considering the $B$-branes on it as objects in the derived category of coherent sheaves, we identify the vertex operators for strings between two branes with elements of the cohomology groups of Ext sheaves. We define the correlation functions for these general vertex operators. Strings stretching between two coherent sheaves are studied as homological extensions of the corresponding branes. In this context, we relate strings between different pairs of branes when there are maps between these branes. We also interpret some strings with ghost number $k$ as obstructions for lifts or extensions of strings with ghost number $k-1$.
Vertex and Propagator in $\\Phi^{4}$ Theory from 4PI Effective Action in Two Dimensions
Carrington, M E
2012-01-01
A set of self-consistent nonlinear integral equations for the four-point vertex and the propagator are derived from the 4-loop 4PI effective action for scalar field theories. This set of integral equations are solved in two dimensions through numerical lattice calculations. We compare the calculated results with those of perturbation theories. We find that the 4PI calculations are well consistent with the perturbation ones in perturbative regions. Non-perturbative results are also obtained in the 4PI formalism when the interacting strength becomes large. Furthermore, the full-momentum dependence of the four-point vertex is easily obtained in the 4PI effective action theories.
Improved Epstein–Glaser renormalization in x -space versus differential renormalization
Gracia-Bondía, José M.; Heidy Gutiérrez; Várilly, Joseph C.
2014-01-01
Renormalization of massless Feynman amplitudes in $x$-space is reexamined here, using almost exclusively real-variable methods. We compute a wealth of concrete examples by means of recursive extension of distributions. This allows us to show perturbative expansions for the four-point and two-point functions at several loop order. To deal with internal vertices, we expound and expand on convolution theory for log-homogeneous distributions. The approach has much in common with differential reno...
Progress toward the Determination of Complete Vertex Operators for The IIB Matrix Model
Kitazawa, Y; Saito, O; Kitazawa, Yoshihisa; Mizoguchi, Shun'ya; Saito, Osamu
2006-01-01
We report on progress in determining the complete form of vertex operators for the IIB matrix model. The exact expressions are obtained for those emitting massless IIB supergravity fields up to sixth order in the light-cone superfield, in which the conjugate gravitino and conjugate two-form vertex operators are newly determined. We also provide a consistency check by computing the kinematical factor of a four-point graviton amplitude in a D-instanton background. We conjecture that the low-energy effective action of the IIB matrix model at large N is given by tree-level supergravity coupled to the vertex operators.
Fermion field renormalization prescriptions
Zhou, Yong
2005-01-01
We discuss all possible fermion field renormalization prescriptions in conventional field renormalization meaning and mainly pay attention to the imaginary part of unstable fermion Field Renormalization Constants (FRC). We find that introducing the off-diagonal fermion FRC leads to the decay widths of physical processes $t\\to c Z$ and $b\\to s \\gamma$ gauge-parameter dependent. We also discuss the necessity of renormalizing the bare fields in conventional quantum field theory.
Koch, N; Kolanoski, H; Siegmund, T; Bergter, J; Eckstein, P; Schubert, Klaus R; Waldi, R; Imhof, M; Ressing, D; Weiss, U; Weseler, S
1995-01-01
A fast second level trigger has been developed for the ARGUS experiment which recognizes tracks originating from the interaction region. The processor compares the hits in the ARGUS Micro Vertex Drift Chamber to 245760 masks stored in random access memories. The masks which are fully defined in three dimensions are able to reject tracks originating in the wall of the narrow beampipe of 10.5\\,mm radius.
Renormalized action improvements
Energy Technology Data Exchange (ETDEWEB)
Zachos, C.
1984-01-01
Finite lattice spacing artifacts are suppressed on the renormalized actions. The renormalized action trajectories of SU(N) lattice gauge theories are considered from the standpoint of the Migdal-Kadanoff approximation. The minor renormalized trajectories which involve representations invariant under the center are discussed and quantified. 17 references.
Functional renormalization group study of fluctuation effects in fermionic superfluids
Energy Technology Data Exchange (ETDEWEB)
Eberlein, Andreas
2013-03-22
This thesis is concerned with ground state properties of two-dimensional fermionic superfluids. In such systems, fluctuation effects are particularly strong and lead for example to a renormalization of the order parameter and to infrared singularities. In the first part of this thesis, the fermionic two-particle vertex is analysed and the fermionic renormalization group is used to derive flow equations for a decomposition of the vertex in charge, magnetic and pairing channels. In the second part, the channel-decomposition scheme is applied to various model systems. In the superfluid state, the fermionic two-particle vertex develops rich and singular dependences on momentum and frequency. After simplifying its structure by exploiting symmetries, a parametrization of the vertex in terms of boson-exchange interactions in the particle-hole and particle-particle channels is formulated, which provides an efficient description of the singular momentum and frequency dependences. Based on this decomposition of the vertex, flow equations for the effective interactions are derived on one- and two-loop level, extending existing channel-decomposition schemes to (i) the description of symmetry breaking in the Cooper channel and (ii) the inclusion of those two-loop renormalization contributions to the vertex that are neglected in the Katanin scheme. In the second part, the superfluid ground state of various model systems is studied using the channel-decomposition scheme for the vertex and the flow equations. A reduced model with interactions in the pairing and forward scattering channels is solved exactly, yielding insights into the singularity structure of the vertex. For the attractive Hubbard model at weak coupling, the momentum and frequency dependence of the two-particle vertex and the frequency dependence of the self-energy are determined on one- and two-loop level. Results for the suppression of the superfluid gap by fluctuations are in good agreement with the literature
Frühwirth, R; Vanlaer, Pascal
2007-01-01
Vertex fitting frequently has to deal with both mis-associated tracks and mis-measured track errors. A robust, adaptive method is presented that is able to cope with contaminated data. The method is formulated as an iterative re-weighted Kalman filter. Annealing is introduced to avoid local minima in the optimization. For the initialization of the adaptive filter a robust algorithm is presented that turns out to perform well in a wide range of applications. The tuning of the annealing schedule and of the cut-off parameter is described, using simulated data from the CMS experiment. Finally, the adaptive property of the method is illustrated in two examples.
Dannheim, D
2015-01-01
The precision physics needs at TeV-scale linear electron-positron colliders (ILC and CLIC) require a vertex-detector system with excellent flavour-tagging capabilities through a meas- urement of displaced vertices. This is essential, for example, for an explicit measurement of the Higgs decays to pairs of b-quarks, c-quarks and gluons. Efficient identification of top quarks in the decay t → W b will give access to the ttH-coupling measurement. In addition to those requirements driven by physics arguments, the CLIC bunch structure calls for hit tim- ing at the few-ns level. As a result, the CLIC vertex-detector system needs to have excellent spatial resolution, full geometrical coverage extending to low polar angles, extremely low material budget, low occupancy facilitated by time-tagging, and sufficient heat removal from sensors and readout. These considerations challenge current technological limits. A detector concept based on hybrid pixel-detector technology is under development for the CLIC ver- tex det...
Differential Renormalization, the Action Principle and Renormalization Group Calculations
Smirnov, V. A.
1994-01-01
General prescriptions of differential renormalization are presented. It is shown that renormalization group functions are straightforwardly expressed through some constants that naturally arise within this approach. The status of the action principle in the framework of differential renormalization is discussed.
Conservation laws, vertex corrections, and screening in Raman spectroscopy
Maiti, Saurabh; Chubukov, Andrey V.; Hirschfeld, P. J.
2017-07-01
We present a microscopic theory for the Raman response of a clean multiband superconductor, with emphasis on the effects of vertex corrections and long-range Coulomb interaction. The measured Raman intensity, R (Ω ) , is proportional to the imaginary part of the fully renormalized particle-hole correlator with Raman form factors γ (k ⃗) . In a BCS superconductor, a bare Raman bubble is nonzero for any γ (k ⃗) and diverges at Ω =2 Δmax , where Δmax is the largest gap along the Fermi surface. However, for γ (k ⃗) = constant, the full R (Ω ) is expected to vanish due to particle number conservation. It was sometimes stated that this vanishing is due to the singular screening by long-range Coulomb interaction. In our general approach, we show diagrammatically that this vanishing actually holds due to vertex corrections from the same short-range interaction that gives rise to superconductivity. We further argue that long-range Coulomb interaction does not affect the Raman signal for any γ (k ⃗) . We argue that vertex corrections eliminate the divergence at 2 Δmax . We also argue that vertex corrections give rise to sharp peaks in R (Ω ) at Ω <2 Δmin (the minimum gap along the Fermi surface), when Ω coincides with the frequency of one of the collective modes in a superconductor, e.g., Leggett and Bardasis-Schrieffer modes in the particle-particle channel, and an excitonic mode in the particle-hole channel.
Entanglement Renormalization and Wavelets.
Evenbly, Glen; White, Steven R
2016-04-08
We establish a precise connection between discrete wavelet transforms and entanglement renormalization, a real-space renormalization group transformation for quantum systems on the lattice, in the context of free particle systems. Specifically, we employ Daubechies wavelets to build approximations to the ground state of the critical Ising model, then demonstrate that these states correspond to instances of the multiscale entanglement renormalization ansatz (MERA), producing the first known analytic MERA for critical systems.
Renormalization Scheme Dependence and the Renormalization Group Beta Function
Chishtie, F. A.; McKeon, D. G. C.
2016-01-01
The renormalization that relates a coupling "a" associated with a distinct renormalization group beta function in a given theory is considered. Dimensional regularization and mass independent renormalization schemes are used in this discussion. It is shown how the renormalization $a^*=a+x_2a^2$ is related to a change in the mass scale $\\mu$ that is induced by renormalization. It is argued that the infrared fixed point is to be a determined in a renormalization scheme in which the series expan...
Non-Abelian Ball-Chiu vertex for arbitrary Euclidean momenta
Aguilar, A C; Ferreira, M N; Papavassiliou, J
2016-01-01
We determine the non-Abelian version of the four longitudinal form factors of the quark-gluon vertex, using exact expressions derived from the Slavnov-Taylor identity that this vertex satisfies. In addition to the quark and ghost propagators, a key ingredient of the present approach is the quark-ghost scattering kernel, which is computed within the one-loop dressed approximation. The vertex form factors obtained from this procedure are evaluated for arbitrary Euclidean momenta, and display features not captured by the well-known Ball-Chiu vertex, deduced from the Abelian (ghost-free) Ward identity. The potential phenomenological impact of these results is evaluated through the study of special renormalization-point-independent combinations, which quantify the strength of the interaction kernels appearing in the standard quark gap and Bethe-Salpeter equations.
Constructive Renormalization of 2-dimensional Grosse-Wulkenhaar Model
Wang, Zhituo
2012-01-01
In this talk we briefly report the recent work on the construction of the 2-dimensional Grosse-Wulkenhaar model with the method of loop vertex expansion. We treat renormalization with this new tool, adapt Nelson's argument and prove Borel summability of the perturbation series. This is the first non-commutative quantum field theory model to be built in a non-perturbative sense.
EXISTENCE FOR SECOND-ORDER FOUR-POINT BOUNDARY VALUE PROBLEM AT RESONANCE
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
This paper is concerned with the existence of solutions for a second-order four-point boundary value problem at resonance. The main methods depend on the technique of the upper and lower solutions and the coincidence degree theory.
Resolution enhancement of scanning four-point-probe measurements on two-dimensional systems
DEFF Research Database (Denmark)
Hansen, Torben Mikael; Stokbro, Kurt; Hansen, Ole;
2003-01-01
A method to improve the resolution of four-point-probe measurements of two-dimensional (2D) and quasi-2D systems is presented. By mapping the conductance on a dense grid around a target area and postprocessing the data, the resolution can be improved by a factor of approximately 50 to better than 1....../15 of the four-point-probe electrode spacing. The real conductance sheet is simulated by a grid of discrete resistances, which is optimized by means of a standard optimization algorithm, until the simulated voltage-to-current ratios converges with the measurement. The method has been tested against simulated...... data as well as real measurements and is found to successfully deconvolute the four-point-probe measurements. In conjunction with a newly developed scanning four-point probe with electrode spacing of 1.1 µm, the method can resolve the conductivity with submicron resolution. ©2003 American Institute...
Is Abdominal Muscle Activity Different from Lumbar Muscle Activity during Four-Point Kneeling?
Soraya Pirouzi; Farahnaz Emami; Shohreh Taghizadeh; Ali Ghanbari
2013-01-01
Background: Stabilization exercises can improve the performance of trunk and back muscles, which are effective in the prevention and treatment of low back pain. The four-point kneeling exercise is one of the most common types of stabilization exercises. This quasi-experimental study aimed to evaluate and compare the level of activation between abdominal and lumbar muscles in the different stages of the four-point kneeling exercise. Methods: The present study was conducted on 30 healthy wom...
Conductivity of individual particles measured by a microscopic four-point-probe method
Ling Sun; Jianjun Wang; Elmar Bonaccurso
2013-01-01
We introduce a technique for measuring the conductivity of individual hybrid metal, semiconducting core-shell and full-metal conducting particles by a microscopic four-point probe (μ-4PP) method. The four-point probe geometry allows for minimizing contact resistances between electrodes and particles. By using a focused ion beam we fabricate platinum nanoleads between four microelectrodes on a silicon chip and an individual particle, and determine the particle's conductivity via sensitive curr...
Renormalization and effective lagrangians
Polchinski, Joseph
1984-01-01
There is a strong intuitive understanding of renormalization, due to Wilson, in terms of the scaling of effective lagrangians. We show that this can be made the basis for a proof of perturbative renormalization. We first study renormalizability in the language of renormalization group flows for a toy renormalization group equation. We then derive an exact renormalization group equation for a four-dimensional λø 4 theory with a momentum cutoff. We organize the cutoff dependence of the effective lagrangian into relevant and irrelevant parts, and derive a linear equation for the irrelevant part. A lengthy but straightforward argument establishes that the piece identified as irrelevant actually is so in perturbation theory. This implies renormalizability. The method extends immediately to any system in which a momentum-space cutoff can be used, but the principle is more general and should apply for any physical cutoff. Neither Weinberg's theorem nor arguments based on the topology of graphs are needed.
Renormalization for Philosophers
Butterfield, Jeremy
2014-01-01
We have two aims. The main one is to expound the idea of renormalization in quantum field theory, with no technical prerequisites (Sections 2 and 3). Our motivation is that renormalization is undoubtedly one of the great ideas, and great successes, of twentieth-century physics. Also it has strongly influenced in diverse ways, how physicists conceive of physical theories. So it is of considerable philosophical interest. Second, we will briefly relate renormalization to Ernest Nagel's account of inter-theoretic relations, especially reduction (Section 4). One theme will be a contrast between two approaches to renormalization. The old approach, which prevailed from ca. 1945 to 1970, treated renormalizability as a necessary condition for being an acceptable quantum field theory. On this approach, it is a piece of great good fortune that high energy physicists can formulate renormalizable quantum field theories that are so empirically successful. But the new approach to renormalization (from 1970 onwards) explains...
Emergent geometry from field theory: Wilson's renormalization group revisited
Kim, Ki-Seok; Park, Chanyong
2016-06-01
We find a geometrical description from a field theoretical setup based on Wilson's renormalization group in real space. We show that renormalization group equations of coupling parameters encode the metric structure of an emergent curved space, regarded to be an Einstein equation for the emergent gravity. Self-consistent equations of local order-parameter fields with an emergent metric turn out to describe low-energy dynamics of a strongly coupled field theory, analogous to the Maxwell equation of the Einstein-Maxwell theory in the AdSd +2 /CFTd +1 duality conjecture. We claim that the AdS3 /CFT2 duality may be interpreted as Landau-Ginzburg theory combined with Wilson's renormalization group, which introduces vertex corrections into the Landau-Ginzburg theory in the large-Ns limit, where Ns is the number of fermion flavors.
Nonperturbative calculation of Green and vertex functions in terms of particle contours
Stefanis, N G
1996-01-01
The infrared regime of fermionic Green and vertex functions is studied analytically within a geometric approach which simulates soft interactions by an {\\it effective} theory of contours. Expanding the particle path integral in terms of dominant contours at large distances, all-order results in the coupling constant are obtained for the renormalized fermion propagator and a universal vertex function with physical characteristics close to those associated with the Isgur-Wise function in the weak decays of heavy mesons. The extension to the ultraviolet regime is scetched.
Conformal Symmetry and Differential Regularization of the Three-Gluon Vertex
Freedman, Daniel Z; Rius, N; Johnson, K; Freedman, Daniel Z.; Grignani, Gianluca; Rius, Nuria; Johnson, Kenneth
1992-01-01
The conformal symmetry of the QCD Lagrangian for massless quarks is broken both by renormalization effects and the gauge fixing procedure. Renormalized primitive divergent amplitudes have the property that their form away from the overall coincident point singularity is fully determined by the bare Lagrangian, and scale dependence is restricted to $\\delta$-functions at the singularity. If gauge fixing could be ignored, one would expect these amplitudes to be conformal invariant for non-coincident points. We find that the one-loop three-gluon vertex function $\\Gamma_{\\mu\
Renormalization aspects of N = 1 Super Yang-Mills theory in the Wess-Zumino gauge
Energy Technology Data Exchange (ETDEWEB)
Capri, M.A.L.; Granado, D.R.; Guimaraes, M.S.; Justo, I.F.; Sorella, S.P.; Vercauteren, D. [UERJ-Universidade do Estado do Rio de Janeiro, Departamento de Fisica Teorica, Instituto de Fisica, Maracana, Rio de Janeiro (Brazil); Mihaila, L. [Karlsruhe Institute of Technology (KIT), Institut fuer Theoretische Teilchenphysik, Karlsruhe (Germany)
2014-04-15
The renormalization of N = 1 Super Yang-Mills theory is analyzed in the Wess-Zumino gauge, employing the Landau condition. An all-orders proof of the renormalizability of the theory is given by means of the Algebraic Renormalization procedure. Only three renormalization constants are needed, which can be identified with the coupling constant, gauge field, and gluino renormalization. The nonrenormalization theorem of the gluon-ghost-antighost vertex in the Landau gauge is shown to remain valid in N = 1 Super Yang-Mills. Moreover, due to the non-linear realization of the supersymmetry in the Wess-Zumino gauge, the renormalization factor of the gauge field turns out to be different from that of the gluino. These features are explicitly checked through a three-loop calculation. (orig.)
The STAR Vertex Position Detector
Llope, W J; Nussbaum, T; Hoffmann, G W; Asselta, K; Brandenburg, J D; Butterworth, J; Camarda, T; Christie, W; Crawford, H J; Dong, X; Engelage, J; Eppley, G; Geurts, F; Hammond, J; Judd, E; McDonald, D L; Perkins, C; Ruan, L; Scheblein, J; Schambach, J J; Soja, R; Xin, K; Yang, C
2014-01-01
The 2x3 channel pseudo Vertex Position Detector (pVPD) in the STAR experiment at RHIC has been upgraded to a 2x19 channel detector in the same acceptance, called the Vertex Position Detector (VPD). This detector is fully integrated into the STAR trigger system and provides the primary input to the minimum-bias trigger in Au+Au collisions. The information from the detector is used both in the STAR Level-0 trigger and offline to measure the location of the primary collision vertex along the beam pipe and the event "start time" needed by other fast-timing detectors in STAR. The offline timing resolution of single detector channels in full-energy Au+Au collisions is ~100 ps, resulting in a start time resolution of a few tens of picoseconds and a resolution on the primary vertex location of ~1 cm.
The renormalization; La normalisation
Energy Technology Data Exchange (ETDEWEB)
Rivasseau, V. [Paris-6 Univ., Lab. de Physique Theorique, 91 - Orsay (France); Gallavotti, G. [Universita di Roma, La Sapienza, Fisica, Roma (Italy); Zinn-Justin, J. [CEA Saclay, Dept. d' Astrophysique, de Physique des Particules, de Physique Nucleaire et de l' Instrumentation Associee, Serv. de Physique Theorique, 91- Gif sur Yvette (France); Connes, A. [College de France, 75 - Paris (France)]|[Institut des Hautes Etudes Scientifiques - I.H.E.S., 91 - Bures sur Yvette (France); Knecht, M. [Centre de Physique Theorique, CNRS-Luminy, 13 - Marseille (France); Mansoulie, B. [CEA Saclay, Dept. d' Astrophysique, de Physique des Particules, de Physique Nucleaire et de l' Instrumentation Associee, Serv. de Physique des Particules, 91- Gif sur Yvette (France)
2002-07-01
This document gathers 6 articles. In the first article the author reviews the theory of perturbative renormalization, discusses its limitations and gives a brief introduction to the powerful point of view of the renormalization group, which is necessary to go beyond perturbation theory and to define renormalization in a constructive way. The second article is dedicated to renormalization group methods by illustrating them with examples. The third article describes the implementation of renormalization ideas in quantum field theory. The mathematical aspects of renormalization are given in the fourth article where the link between renormalization and the Riemann-Hilbert problem is highlighted. The fifth article gives an overview of the main features of the theoretical calculations that have been done in order to obtain accurate predictions for the anomalous magnetic moments of the electron and of the muon within the standard model. The challenge is to make theory match the unprecedented accuracy of the last experimental measurements. The last article presents how ''physics beyond the standard model'' will be revealed at the large hadron collider (LHC) at CERN. This accelerator will be the first to explore the 1 TeV energy range directly. Supersymmetry, extra-dimensions and Higgs boson will be the different challenges. It is not surprising that all theories put forward today to subtend the electro-weak breaking mechanism, predict measurable or even spectacular signals at LHC. (A.C.)
Some finite properties for vertex operator superalgebras
Dong, Chongying; Han, Jianzhi
2011-01-01
Vertex operator superalgebras are studied and various results on rational Vertex operator superalgebras are obtained. In particular, the vertex operator super subalgebras generated by the weight 1/2 and weight 1 subspaces are determined. It is also established that if the even part $V_{\\bar 0}$ of a vertex operator superalgebra $V$ is rational, so is $V.$
c, Aleksandar Ili\\'
2011-01-01
The vertex PI index is a distance--based molecular structure descriptor, that recently found numerous chemical applications. In order to increase diversity of this topological index for bipartite graphs, we introduce weighted version defined as $PI_w (G) = \\sum_{e = uv \\in E} (deg (u) + deg (v)) (n_u (e) + n_v (e))$, where $deg (u)$ denotes the vertex degree of $u$ and $n_u (e)$ denotes the number of vertices of $G$ whose distance to the vertex $u$ is smaller than the distance to the vertex $v$. We establish basic properties of $PI_w (G)$, and prove various lower and upper bounds. In particular, the path $P_n$ has minimal, while the complete tripartite graph $K_{n/3, n/3, n/3}$ has maximal weighed vertex $PI$ index among graphs with $n$ vertices. We also compute exact expressions for the weighted vertex PI index of the Cartesian product of graphs. Finally we present modifications of two inequalities and open new perspectives for the future research.
Non-Perturbative Renormalization
Mastropietro, Vieri
2008-01-01
The notion of renormalization is at the core of several spectacular achievements of contemporary physics, and in the last years powerful techniques have been developed allowing to put renormalization on a firm mathematical basis. This book provides a self-consistent and accessible introduction to the sophisticated tools used in the modern theory of non-perturbative renormalization, allowing an unified and rigorous treatment of Quantum Field Theory, Statistical Physics and Condensed Matter models. In particular the first part of this book is devoted to Constructive Quantum Field Theory, providi
Renormalization of an Abelian Tensor Group Field Theory: Solution at Leading Order
Lahoche, Vincent; Rivasseau, Vincent
2015-01-01
We study a just renormalizable tensorial group field theory of rank six with quartic melonic interactions and Abelian group U(1). We introduce the formalism of the intermediate field, which allows a precise characterization of the leading order Feynman graphs. We define the renormalization of the model, compute its (perturbative) renormalization group flow and write its expansion in terms of effective couplings. We then establish closed equations for the two point and four point functions at leading (melonic) order. Using the effective expansion and its uniform exponential bounds we prove that these equations admit a unique solution at small renormalized coupling.
Sensitivity study of micro four-point probe measurements on small samples
DEFF Research Database (Denmark)
Wang, Fei; Petersen, Dirch Hjorth; Hansen, Torben Mikael
2010-01-01
The authors calculate the sensitivities of micro four-point probe sheet resistance and Hall effect measurements to the local transport properties of nonuniform material samples. With in-line four-point probes, the measured dual configuration sheet resistance is more sensitive near the inner two...... probes than near the outer ones. The sensitive area is defined for infinite film, circular, square, and rectangular test pads, and convergent sensitivities are observed for small samples. The simulations show that the Hall sheet resistance RH in micro Hall measurements with position error suppression...
Resolution enhancement of scanning four-point-probe measurements on two-dimensional systems.
Hansen, Torben Mikael; Stokbro, Kurt; Hansen, Ole; Hassenkam, T.; Shiraki, I.; Hasegawa, S.; Bøggild, Peter
2003-01-01
A method to improve the resolution of four-point-probe measurements of two-dimensional (2D) and quasi-2D systems is presented. By mapping the conductance on a dense grid around a target area and postprocessing the data, the resolution can be improved by a factor of approximately 50 to better than 1/15 of the four-point-probe electrode spacing. The real conductance sheet is simulated by a grid of discrete resistances, which is optimized by means of a standard optimization algorithm, until the ...
Direct measurement of resistance of multiwalled carbon nanotubes using micro four-point probes
DEFF Research Database (Denmark)
Dohn, Søren; Mølhave, Kristian; Bøggild, Peter
2005-01-01
The electrical properties of multiwalled carbon nanotubes was investigated by micro four point probes, fabricated using conventional silicon microfabrication techniques. After positioning of chemical vapour deposition-grown multi-walled carbon nanotubes on a SiO2 substrate, the two- or four-point...... resistance at specific positions along the nanotubes, was measured by microprobes with different microelectrocle spacings. Individual nanotubes were investigated in more detail by measuring current as a function of bias voltage until the point of failure and the results are compared to previously reported...
Singular Renormalization Group Equations
Minoru, HIRAYAMA; Department of Physics, Toyama University
1984-01-01
The possible behaviour of the effective charge is discussed in Oehme and Zimmermann's scheme of the renormalization group equation. The effective charge in an example considered oscillates so violently in the ultraviolet limit that the bare charge becomes indefinable.
Renormalization of supersymmetric theories
Energy Technology Data Exchange (ETDEWEB)
Pierce, D.M.
1998-06-01
The author reviews the renormalization of the electroweak sector of the standard model. The derivation also applies to the minimal supersymmetric standard model. He discusses regularization, and the relation between the threshold corrections and the renormalization group equations. He considers the corrections to many precision observables, including M{sub W} and sin{sup 2}{theta}{sup eff}. He shows that global fits to the data exclude regions of supersymmetric model parameter space and lead to lower bounds on superpartner masses.
Electrical conduction through surface superstructures measured by microscopic four-point probes
DEFF Research Database (Denmark)
Hasegawa, S.; Shiraki, I.; Tanabe, F.
2003-01-01
For in-situ measurements of the local electrical conductivity of well-defined crystal surfaces in ultra-high vacuum, we have developed two kinds of microscopic four-point probe methods. One involves a "four-tip STM prober," in which four independently driven tips of a scanning tunneling microscope...
Direct measurement of surface-state conductance by microscopic four-point probe method
DEFF Research Database (Denmark)
Hasegawa, S.; Shiraki, I.; Tanikawa, T.
2002-01-01
For in situ measurements of local electrical conductivity of well defined crystal surfaces in ultrahigh vacuum, we have developed microscopic four-point probes with a probe spacing of several micrometres, installed in a scanning-electron - microscope/electron-diffraction chamber. The probe...
Developing Multidimensional Likert Scales Using Item Factor Analysis: The Case of Four-Point Items
Asún, Rodrigo A.; Rdz-Navarro, Karina; Alvarado, Jesús M.
2016-01-01
This study compares the performance of two approaches in analysing four-point Likert rating scales with a factorial model: the classical factor analysis (FA) and the item factor analysis (IFA). For FA, maximum likelihood and weighted least squares estimations using Pearson correlation matrices among items are compared. For IFA, diagonally weighted…
Design of a miniature electrolyte conductivity probe using ISFETs in a four point configuration
Volanschi, A.; Olthuis, W.; Bergveld, P.
1994-01-01
In this work the design, fabrication and testing of a four point electrode configuration based on ISFETs for the measurement of electrolytic conductivity are presented. The final design uses a distance between the ISFET gates of only 100 ¿m allowing a chip area in contact with the electrolyte of 2.2
The conductivity of Bi(111) investigated with nanoscale four point probes
DEFF Research Database (Denmark)
Wells, J.W.; Handrup, K.; Kallehauge, J.F.;
2008-01-01
The room temperature conductance of Bi(111) was measured using microscopic four point probes with a contact spacing down to 500 nm. The conductance is remarkably similar to that of the bulk, indicating that surface scattering is not a major mechanism for restricting the mobility at this length...
Degradation Assessment in IGBT Modules Using Four-Point Probing Approach
DEFF Research Database (Denmark)
Pedersen, Kristian Bonderup; Kristensen, Peter Kjær; Popok, Vladimir;
2015-01-01
Four-point probing of electrical parameters on various components of IGBT modules is suggested as an approach for the estimation of degradation in stressed devices. By comparison of these parameters for stressed and new components one can evaluate an overall degradation of the module and find out...
Bubble shape and orientation determination with a four-point optical fibre probe
Guet, S.; Luther, S.; Ooms, G.
2003-01-01
We propose a new method to estimate the aspect ratio and orientation of bubbles by using their time series obtained with a four-point optical-fibre probe. The feasibility and accuracy of the method was first analysed by using synthetic bubble–probe interaction data and single bubble experiments in p
Symmetric point four-point functions at one loop in QCD
Gracey, J. A.
2017-03-01
We evaluate the quartic ghost and quark Green's functions as well as the gluon-ghost, gluon-quark and ghost-quark four-point functions of quantum chromodynamics at one loop at the fully symmetric point in a linear covariant gauge. Similar expressions for the analogous Green's functions in quantum electrodynamics are also provided.
Review of electrical characterization of ultra-shallow junctions with micro four-point probes
DEFF Research Database (Denmark)
Petersen, Dirch Hjorth; Hansen, Ole; Hansen, Torben M.;
2010-01-01
techniques will become even more evident. In several recent studies micro four-point probe (M4PP) has been demonstrated as a reliable high precision metrology method for both sheet resistance and Hall effect measurements of ultra-shallow implants and has revealed a promising potential for carrier profiling....
Existence of Solutions for Nonlinear Four-Point -Laplacian Boundary Value Problems on Time Scales
Directory of Open Access Journals (Sweden)
Topal SGulsan
2009-01-01
Full Text Available We are concerned with proving the existence of positive solutions of a nonlinear second-order four-point boundary value problem with a -Laplacian operator on time scales. The proofs are based on the fixed point theorems concerning cones in a Banach space. Existence result for -Laplacian boundary value problem is also given by the monotone method.
Renormalization of fermion mixing
Energy Technology Data Exchange (ETDEWEB)
Schiopu, R.
2007-05-11
Precision measurements of phenomena related to fermion mixing require the inclusion of higher order corrections in the calculation of corresponding theoretical predictions. For this, a complete renormalization scheme for models that allow for fermion mixing is highly required. The correct treatment of unstable particles makes this task difficult and yet, no satisfactory and general solution can be found in the literature. In the present work, we study the renormalization of the fermion Lagrange density with Dirac and Majorana particles in models that involve mixing. The first part of the thesis provides a general renormalization prescription for the Lagrangian, while the second one is an application to specific models. In a general framework, using the on-shell renormalization scheme, we identify the physical mass and the decay width of a fermion from its full propagator. The so-called wave function renormalization constants are determined such that the subtracted propagator is diagonal on-shell. As a consequence of absorptive parts in the self-energy, the constants that are supposed to renormalize the incoming fermion and the outgoing antifermion are different from the ones that should renormalize the outgoing fermion and the incoming antifermion and not related by hermiticity, as desired. Instead of defining field renormalization constants identical to the wave function renormalization ones, we differentiate the two by a set of finite constants. Using the additional freedom offered by this finite difference, we investigate the possibility of defining field renormalization constants related by hermiticity. We show that for Dirac fermions, unless the model has very special features, the hermiticity condition leads to ill-defined matrix elements due to self-energy corrections of external legs. In the case of Majorana fermions, the constraints for the model are less restrictive. Here one might have a better chance to define field renormalization constants related by
Belle II Silicon Vertex Detector
Mohanty, Gagan B
2015-01-01
The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by a vertex detector, which comprises two layers of pixelated silicon detector and four layers of silicon vertex detector. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector that is aimed to be commissioned towards the middle of 2017.
Ultrasound-guided bilateral dual transversus abdominis plane block: a new four-point approach
DEFF Research Database (Denmark)
Neimann, Jens Dupont Børglum; Maschmann, C; Belhage, B;
2011-01-01
Background: We describe a new ultrasound-guided bilateral dual transversus abdominis plane block. Our hypothesis was that we could anaesthetize both the upper (Th6–Th9) and the lower (Th10–Th12) abdominal wall bilaterally using a four-point single-shot technique to provide effective post-operativ......Background: We describe a new ultrasound-guided bilateral dual transversus abdominis plane block. Our hypothesis was that we could anaesthetize both the upper (Th6–Th9) and the lower (Th10–Th12) abdominal wall bilaterally using a four-point single-shot technique to provide effective post...... scale 0–10) from a mean of 8.2 to a mean of 2.2 10 min after block performance (P
DEFF Research Database (Denmark)
Wang, Fei; Petersen, Dirch Hjorth; Østerberg, Frederik Westergaard
2009-01-01
In this paper, we discuss a probe spacing dependence study in order to estimate the accuracy of micro four-point probe measurements on inhomogeneous samples. Based on sensitivity calculations, both sheet resistance and Hall effect measurements are studied for samples (e.g. laser annealed samples...... the probe spacing is smaller than 1/40 of the variation wavelength, micro four-point probes can provide an accurate record of local properties with less than 1% measurement error. All the calculations agree well with previous experimental results.......) with periodic variations of sheet resistance, sheet carrier density, and carrier mobility. With a variation wavelength of Â¿, probe spacings from 0.0012 to 1002 have been applied to characterize the local variations. The calculations show that the measurement error is highly dependent on the probe spacing. When...
Directory of Open Access Journals (Sweden)
Jauhar Fajrin
2017-03-01
Full Text Available This paper presents a comparison of theoretical and experimental deflection of a hybrid sandwich panel under four-point bending load. The paper initially presents few basic equations developed under three-point load, followed by development of model under four-point bending load and a comparative analysis between theoretical and experimental results. It was found that the proposed model for predicting the deflection of hybrid sandwich panels provided fair agreement with the experimental values. Most of the sandwich panels showed theoretical deflection values higher than the experimental values, which is desirable in the design. It was also noticed that the introduction of intermediate layer does not contribute much to reduce the deflection of sandwich panel as the main contributor for the total deflection was the shear deformation of the core that mostly determined by the geometric of the samples and the thickness of the core.
Conductivity of individual particles measured by a microscopic four-point-probe method.
Sun, Ling; Wang, Jianjun; Bonaccurso, Elmar
2013-01-01
We introduce a technique for measuring the conductivity of individual hybrid metal, semiconducting core-shell and full-metal conducting particles by a microscopic four-point probe (μ-4PP) method. The four-point probe geometry allows for minimizing contact resistances between electrodes and particles. By using a focused ion beam we fabricate platinum nanoleads between four microelectrodes on a silicon chip and an individual particle, and determine the particle's conductivity via sensitive current and voltage measurements. Up to sixteen particles can be taken up by each chip, which allows for multiple conductivity measurements by simply multiplexing the electric contacts connected to a multimeter. Although, for demonstration, we used full Au (conducting) and Ag-coated latex particles (semiconducting) of a few micrometers in diameter, the method can be applied to other types of conducting or semiconducting particles of different diameters.
Four-point correlation function of stress-energy tensors in N=4 superconformal theories
Korchemsky, G P
2015-01-01
We derive the explicit expression for the four-point correlation function of stress-energy tensors in four-dimensional N=4 superconformal theory. We show that it has a remarkably simple and suggestive form allowing us to predict a large class of four-point correlation functions involving the stress-energy tensor and other conserved currents. We then apply the obtained results on the correlation functions to computing the energy-energy correlations, which measure the flow of energy in the final states created from the vacuum by a source. We demonstrate that they are given by a universal function independent of the choice of the source. Our analysis relies only on N=4 superconformal symmetry and does not use the dynamics of the theory.
Four-point bending test of the Bauschinger effect in prestrained IF steel thin sheet
Energy Technology Data Exchange (ETDEWEB)
Kato, Hiroyuki, E-mail: hkato@eng.hokudai.ac.jp [Mechanical and Space Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Sasaki, Kazuaki [Mechanical and Space Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Mori, T. [National Defense Academy, Yokosuka 239-0811 (Japan)
2015-08-26
The Bauschinger effect in a 1 mm thick sheet of interstitial free (IF) steel was examined by tensile testing (prestraining) and subsequent four-point bending. The effect was absent when the prestrain was below 4% and was present when the prestrain was above 4%. The Bauschinger effect parameter determined the elastic back stress which developed after prestraining. The occurrence of back stress coincided with the development of dislocation cell structures, observed with transmission electron microscopy.
On the ABJM four-point amplitude at three loops and BDS exponentiation
Bianchi, Marco S.; Leoni, Matias
2014-11-01
We study the three-loop four-point amplitude in ABJM theory. We determine the dual conformal invariant integrals with highest number of propagators and fix their coefficients by two-particle cuts. Evaluating such a combination of integrals in dimensional regularization we provide evidence for exponentiation of the amplitude, including the finite terms. In addition we show that the three-loop amplitude can be expressed in terms of classical polylogarithms of uniform degree of transcendentality.
On the ABJM four-point amplitude at three loops and BDS exponentiation
Bianchi, Marco S
2014-01-01
We study the three-loop four-point amplitude in ABJM theory. We determine the dual conformal invariant integrals with highest number of propagators and fix their coefficients by two-particle cuts. Evaluating such a combination of integrals in dimensional regularization we provide evidence for exponentiation of the amplitude, including the finite terms. In addition we show that the three-loop amplitude can be expressed in terms of classical polylogarithms of uniform degree of transcendentality.
Lengthscale dependence of dynamic four-point susceptibilities in glass formers
Chandler, David; Juan P Garrahan; Jack, Robert L.; Maibaum, Lutz; Pan, Albert C.
2006-01-01
Dynamical four-point susceptibilities measure the extent of spatial correlations in the dynamics of glass forming systems. We show how these susceptibilities depend on the length scales that necessarily form part of their definition. The behaviour of these susceptibilities is estimated by means of an analysis in terms of renewal processes within the context of dynamic facilitation. The analytic results are confirmed by numerical simulations of an atomistic model glass-former, and of two kinet...
Fourth-Order Four-Point Boundary Value Problem: A Solutions Funnel Approach
Directory of Open Access Journals (Sweden)
Panos K. Palamides
2012-01-01
Full Text Available We investigate the existence of positive or a negative solution of several classes of four-point boundary-value problems for fourth-order ordinary differential equations. Although these problems do not always admit a (positive Green's function, the obtained solution is still of definite sign. Furthermore, we prove the existence of an entire continuum of solutions. Our technique relies on the continuum property (connectedness and compactness of the solutions funnel (Kneser's Theorem, combined with the corresponding vector field.
Wang, Fei; Petersen, Dirch Hjorth; Østerberg, Frederik Westergaard; Hansen, Ole
2009-01-01
In this paper, we discuss a probe spacing dependence study in order to estimate the accuracy of micro four-point probe measurements on inhomogeneous samples. Based on sensitivity calculations, both sheet resistance and Hall effect measurements are studied for samples (e.g. laser annealed samples) with periodic variations of sheet resistance, sheet carrier density, and carrier mobility. With a variation wavelength of Â¿, probe spacings from 0.0012 to 1002 have been applied to characterize the ...
Dynamic Carrying Capacity Analysis of Double-Row Four-Point Contact Ball Slewing Bearing
Yunfeng Li; Di Jiang
2015-01-01
Carrying capacity is the most important performance index for slewing bearings. Maximizing the carrying capacity of slewing bearing is one pursuing goal for the bearing designer; this is usually realized by optimizing the design parameters. A method of analyzing the carrying capacity of double-row four-point contact ball slewing bearing by using dynamic carrying capacity surfaces was proposed in this paper. Based on the dynamic load carrying capacity surface of the slewing bearing, the effect...
Revenue Management Performance Drivers: An Empirical Analysis at Four Points by Sheraton
Shroff, Avinash
2009-01-01
The purpose of this management project is to analyse the current and future scenario of the revenue streams of the Four Points hotel Mumbai in India. Revenue Management (RM) is an important tool for matching supply and demand by segmenting customers into different segments based on their willingness-to-pay and allocating scarce capacity to the different segments in a way that maximizes firm revenues. The benefits of RM are well accepted in the hospitality industry, and the technical aspects o...
Four-point correlation functions in the AdS/CFT correspondence.
Energy Technology Data Exchange (ETDEWEB)
Chalmers, G.; Schalm, K.
1999-02-09
We examine correlation functions within the correspondence between gauged supergravity on anti-de Sitter space and N = 4 super Yang-Mills theory in Minkowski space. The imaginary parts of four-point functions in momentum space are computed, in addition to particular examples of three-point functions. Exchange diagrams for gravitons are included. The results indicate additional structure in N = 4 super Yang-Mills theory at strong 't Hooft coupling and in the large N limit.
Manifest Ultraviolet Behavior in the Three-Loop Four-Point Amplitude of N=8 Supergravity
Energy Technology Data Exchange (ETDEWEB)
Bern, Z.; Carrasco, J.J.M.; /UCLA; Dixon, L.J.; /SLAC; Johansson, H.; /UCLA; Roiban, R.; /Penn State U.
2008-09-03
Using the method of maximal cuts, we obtain a form of the three-loop four-point scattering amplitude of N = 8 supergravity in which all ultraviolet cancellations are made manifest. The Feynman loop integrals that appear have a graphical representation with only cubic vertices, and numerator factors that are quadratic in the loop momenta, rather than quartic as in the previous form. This quadratic behavior reflects cancellations beyond those required for finiteness, and matches the quadratic behavior of the three-loop four-point scattering amplitude in N = 4 super-Yang-Mills theory. By direct integration we confirm that no additional cancellations remain in the N = 8 supergravity amplitude, thus demonstrating that the critical dimension in which the first ultraviolet divergence occurs at three loops is D{sub c} = 6. We also give the values of the three-loop divergences in D = 7, 9, 11. In addition, we present the explicitly color-dressed three-loop four-point amplitude of N = 4 super-Yang-Mills theory.
Capillary-wave models and the effective-average-action scheme of functional renormalization group.
Jakubczyk, P
2011-08-01
We reexamine the functional renormalization-group theory of wetting transitions. As a starting point of the analysis we apply an exact equation describing renormalization group flow of the generating functional for irreducible vertex functions. We show how the standard nonlinear renormalization group theory of wetting transitions can be recovered by a very simple truncation of the exact flow equation. The derivation makes all the involved approximations transparent and demonstrates the applicability of the approach in any spatial dimension d≥2. Exploiting the nonuniqueness of the renormalization-group cutoff scheme, we find, however, that the capillary parameter ω is a scheme-dependent quantity below d=3. For d=3 the parameter ω is perfectly robust against scheme variation.
Keldysh functional renormalization group for electronic properties of graphene
Fräßdorf, Christian; Mosig, Johannes E. M.
2017-03-01
We construct a nonperturbative nonequilibrium theory for graphene electrons interacting via the instantaneous Coulomb interaction by combining the functional renormalization group method with the nonequilibrium Keldysh formalism. The Coulomb interaction is partially bosonized in the forward scattering channel resulting in a coupled Fermi-Bose theory. Quantum kinetic equations for the Dirac fermions and the Hubbard-Stratonovich boson are derived in Keldysh basis, together with the exact flow equation for the effective action and the hierarchy of one-particle irreducible vertex functions, taking into account a possible nonzero expectation value of the bosonic field. Eventually, the system of equations is solved approximately under thermal equilibrium conditions at finite temperature, providing results for the renormalized Fermi velocity and the static dielectric function, which extends the zero-temperature results of Bauer et al., Phys. Rev. B 92, 121409 (2015), 10.1103/PhysRevB.92.121409.
Dynamical gap generation in graphene with frequency dependent renormalization effects
Carrington, M E; von Smekal, L; Thoma, M H
2016-01-01
We study the frequency dependencies in the renormalization of the fermion Greens function for the $\\pi$-band electrons in graphene and their influence on the dynamical gap generation at sufficiently strong interaction. Adopting the effective QED-like description for the low-energy excitations within the Dirac-cone region we self consistently solve the fermion Dyson-Schwinger equation in various approximations for the photon propagator and the vertex function with special emphasis on frequency dependent Lindhard screening and retardation effects.
A Novel Vertex Affinity for Community Detection
Energy Technology Data Exchange (ETDEWEB)
Yoo, Andy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sanders, Geoffrey [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Henson, Van [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vassilevski, Panayot [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-10-05
We propose a novel vertex affinity measure in this paper. The new vertex affinity quantifies the proximity between two vertices in terms of their clustering strength and is ideal for such graph analytics applications as community detection. We also developed a framework that combines simple graph searches and resistance circuit formulas to compute the vertex affinity efficiently. We study the properties of the new affinity measure empirically in comparison to those of other popular vertex proximity metrics. Our results show that the existing metrics are ill-suited for community detection due to their lack of fundamental properties that are essential for correctly capturing inter- and intra-cluster vertex proximity.
Is Abdominal Muscle Activity Different from Lumbar Muscle Activity during Four-Point Kneeling?
Directory of Open Access Journals (Sweden)
Soraya Pirouzi
2013-12-01
Full Text Available Background: Stabilization exercises can improve the performance of trunk and back muscles, which are effective in the prevention and treatment of low back pain. The four-point kneeling exercise is one of the most common types of stabilization exercises. This quasi-experimental study aimed to evaluate and compare the level of activation between abdominal and lumbar muscles in the different stages of the four-point kneeling exercise. Methods: The present study was conducted on 30 healthy women between 20 and 30 years old. Muscle activity was recorded bilaterally from transversus abdominis, internal oblique, and multifidus muscles with an electromyography (EMG device during the different stages of the four-point kneeling exercise. All the collected EMG data were normalized to the percentage of maximum voluntary isometric contraction. The repeated measures ANOVA and paired t-test were used for the statistical analysis of the data. Results: A comparison between mean muscle activation in right arm extension and left leg extension showed that left internal oblique and left transverse abdominis muscles produced greater activation during left leg extension (P<0.05. The comparison of mean muscle activation between right arm extension and the bird-dog position showed that, except for the right internal oblique, all the muscles produced higher activation in the bird-dog stage (P<0.05. In comparison to the bird-dog stage, the left multifidus showed high activation during left leg extension (P<0.05. Conclusion: The results of this study showed that the activity of all the above-mentioned muscles during quadruped exercise can provide stability, coordination, and smoothness of movements.
An all order identity between ABJM and N=4 SYM four-point amplitudes
Bianchi, Marco S; Penati, Silvia
2011-01-01
We derive an exact algebraic identity between the two-loop four-point amplitude in ABJM theory and the corresponding one-loop amplitude in N=4 SYM theory. This identity generalizes previous partial results to an exact relation valid at all orders in the IR regulator. Moreover, it allows to conjecture an exact iterative expression for the complete three dimensional amplitude in terms of the BDS ansatz for the four dimensional one, indicating that the strict relation between the two amplitudes experimented at two loops might propagate to all orders. In particular, an almost complete expression for the ABJM amplitude at four loops is derived.
Automatized channel for resistivity measurements in layered materials by four-point probe technique
Gryaznov, A. O.; Savchenko, S. S.; Vokhmintsev, A. S.; Weinstein, I. A.
2016-09-01
An automatized channel for measuring the resistivity in materials by the four-point probe technique was developed. The installation was based on Cascade Microtech MPS150 microprobe station, National Instruments PXIe-4143 power supply unit and PXI-4072 digital multimeter. Registration modes of surface and bulk specific resistance for samples with positioning the probes in a line or at square vertices were implemented. Measurements under corresponding modes were carried out for metallic, semiconducting bulk samples and thin coatings. Conductive and optical properties of 10, 20 and 30 nm Au layers formed on quartz glass by magnetron sputtering were investigated.
Belle II silicon vertex detector
Adamczyk, K.; Aihara, H.; Angelini, C.; Aziz, T.; Babu, V.; Bacher, S.; Bahinipati, S.; Barberio, E.; Baroncelli, Ti.; Baroncelli, To.; Basith, A. K.; Batignani, G.; Bauer, A.; Behera, P. K.; Bergauer, T.; Bettarini, S.; Bhuyan, B.; Bilka, T.; Bosi, F.; Bosisio, L.; Bozek, A.; Buchsteiner, F.; Casarosa, G.; Ceccanti, M.; Červenkov, D.; Chendvankar, S. R.; Dash, N.; Divekar, S. T.; Doležal, Z.; Dutta, D.; Enami, K.; Forti, F.; Friedl, M.; Hara, K.; Higuchi, T.; Horiguchi, T.; Irmler, C.; Ishikawa, A.; Jeon, H. B.; Joo, C. W.; Kandra, J.; Kang, K. H.; Kato, E.; Kawasaki, T.; Kodyš, P.; Kohriki, T.; Koike, S.; Kolwalkar, M. M.; Kvasnička, P.; Lanceri, L.; Lettenbicher, J.; Maki, M.; Mammini, P.; Mayekar, S. N.; Mohanty, G. B.; Mohanty, S.; Morii, T.; Nakamura, K. R.; Natkaniec, Z.; Negishi, K.; Nisar, N. K.; Onuki, Y.; Ostrowicz, W.; Paladino, A.; Paoloni, E.; Park, H.; Pilo, F.; Profeti, A.; Rashevskaya, I.; Rao, K. K.; Rizzo, G.; Rozanska, M.; Sandilya, S.; Sasaki, J.; Sato, N.; Schultschik, S.; Schwanda, C.; Seino, Y.; Shimizu, N.; Stypula, J.; Suzuki, J.; Tanaka, S.; Tanida, K.; Taylor, G. N.; Thalmeier, R.; Thomas, R.; Tsuboyama, T.; Uozumi, S.; Urquijo, P.; Vitale, L.; Volpi, M.; Watanuki, S.; Watson, I. J.; Webb, J.; Wiechczynski, J.; Williams, S.; Würkner, B.; Yamamoto, H.; Yin, H.; Yoshinobu, T.
2016-09-01
The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector.
Belle II silicon vertex detector
Energy Technology Data Exchange (ETDEWEB)
Adamczyk, K. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Aihara, H. [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Angelini, C. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Aziz, T.; Babu, V. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Bacher, S. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Bahinipati, S. [Indian Institute of Technology Bhubaneswar, Satya Nagar (India); Barberio, E.; Baroncelli, Ti.; Baroncelli, To. [School of Physics, University of Melbourne, Melbourne, Victoria 3010 (Australia); Basith, A.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Batignani, G. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bauer, A. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Behera, P.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Bergauer, T. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Bettarini, S. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bhuyan, B. [Indian Institute of Technology Guwahati, Assam 781039 (India); Bilka, T. [Faculty of Mathematics and Physics, Charles University, 121 16 Prague (Czech Republic); Bosi, F. [INFN Sezione di Pisa, I-56127 Pisa (Italy); Bosisio, L. [Dipartimento di Fisica, Università di Trieste, I-34127 Trieste (Italy); INFN Sezione di Trieste, I-34127 Trieste (Italy); and others
2016-09-21
The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector.
Primordial non-Gaussianity in noncanonical warm inflation: Three- and four-point correlations
Zhang, Xiao-Min; Ma, Hong-Yang; Chu, Peng-Cheng; Zhu, Jian-Yang
2017-08-01
Non-Gaussianity generated in inflation can be contributed by two parts. The first part, denoted by fNL δ N, is the contribution from the four-point correlation of the inflaton field which can be calculated using δ N formalism, and the second part, denoted by fNL int , is the contribution from the three-point correlation function of the inflaton field. We consider the two contributions to the non-Gaussianity in noncanonical warm inflation throughout (noncanonical warm inflation is a new inflationary model which is proposed in X. M. Zhang and J. Y. Zhu, Phys. Rev. D 90, 123519 (2014), 10.1103/PhysRevD.90.123519). We find the two contributions are complementary to each other. The four-point correlation contribution to the non-Gaussianity is overwhelmed by the three-point one in the strong noncanonical limit, while the conclusion is the opposite in the canonical case. We also discuss the influence of the field redefinition, thermal dissipative effect and noncanonical effect to the non-Gaussianity in noncanonical warm inflation.
Natural constraints on the gluon-quark vertex
Binosi, Daniele; Chang, Lei; Papavassiliou, Joannis; Qin, Si-Xue; Roberts, Craig D.
2017-02-01
In principle, the strong-interaction sector of the standard model is characterized by a unique renormalization-group-invariant (RGI) running interaction and a unique form for the dressed-gluon-quark vertex, Γμ; but, whilst much has been learnt about the former, the latter is still obscure. In order to improve this situation, we use a RGI running-interaction that reconciles top-down and bottom-up analyses of the gauge sector in quantum chromodynamics (QCD) to compute dressed-quark gap equation solutions with 1,660,000 distinct Ansätze for Γμ. Each one of the solutions is then tested for compatibility with three physical criteria and, remarkably, we find that merely 0.55% of the solutions survive the test. Evidently, even a small selection of observables places extremely tight bounds on the domain of realistic vertex Ansätze. This analysis and its results should prove useful in constraining insightful contemporary studies of QCD and hadronic phenomena.
Computing the effective action with the functional renormalization group
Energy Technology Data Exchange (ETDEWEB)
Codello, Alessandro [CP3-Origins and the Danish IAS University of Southern Denmark, Odense (Denmark); Percacci, Roberto [SISSA, Trieste (Italy); INFN, Sezione di Trieste, Trieste (Italy); Rachwal, Leslaw [Fudan University, Department of Physics, Center for Field Theory and Particle Physics, Shanghai (China); Tonero, Alberto [ICTP-SAIFR and IFT, Sao Paulo (Brazil)
2016-04-15
The ''exact'' or ''functional'' renormalization group equation describes the renormalization group flow of the effective average action Γ{sub k}. The ordinary effective action Γ{sub 0} can be obtained by integrating the flow equation from an ultraviolet scale k = Λ down to k = 0. We give several examples of such calculations at one-loop, both in renormalizable and in effective field theories. We reproduce the four-point scattering amplitude in the case of a real scalar field theory with quartic potential and in the case of the pion chiral Lagrangian. In the case of gauge theories, we reproduce the vacuum polarization of QED and of Yang-Mills theory. We also compute the two-point functions for scalars and gravitons in the effective field theory of scalar fields minimally coupled to gravity. (orig.)
Computing the effective action with the functional renormalization group
DEFF Research Database (Denmark)
Codello, Alessandro; Percacci, Roberto; Rachwał, Lesław
2016-01-01
The “exact” or “functional” renormalization group equation describes the renormalization group flow of the effective average action Γ k. The ordinary effective action Γ 0 can be obtained by integrating the flow equation from an ultraviolet scale k= Λ down to k= 0. We give several examples of such...... of QED and of Yang–Mills theory. We also compute the two-point functions for scalars and gravitons in the effective field theory of scalar fields minimally coupled to gravity.......The “exact” or “functional” renormalization group equation describes the renormalization group flow of the effective average action Γ k. The ordinary effective action Γ 0 can be obtained by integrating the flow equation from an ultraviolet scale k= Λ down to k= 0. We give several examples...... of such calculations at one-loop, both in renormalizable and in effective field theories. We reproduce the four-point scattering amplitude in the case of a real scalar field theory with quartic potential and in the case of the pion chiral Lagrangian. In the case of gauge theories, we reproduce the vacuum polarization...
Compressive Spectral Renormalization Method
Bayindir, Cihan
2016-01-01
In this paper a novel numerical scheme for finding the sparse self-localized states of a nonlinear system of equations with missing spectral data is introduced. As in the Petviashivili's and the spectral renormalization method, the governing equation is transformed into Fourier domain, but the iterations are performed for far fewer number of spectral components (M) than classical versions of the these methods with higher number of spectral components (N). After the converge criteria is achieved for M components, N component signal is reconstructed from M components by using the l1 minimization technique of the compressive sampling. This method can be named as compressive spectral renormalization (CSRM) method. The main advantage of the CSRM is that, it is capable of finding the sparse self-localized states of the evolution equation(s) with many spectral data missing.
Lavrov, Peter M
2010-01-01
The renormalization of general gauge theories on flat and curved space-time backgrounds is considered within the Sp(2)-covariant quantization method. We assume the existence of a gauge-invariant and diffeomorphism invariant regularization. Using the Sp(2)-covariant formalism one can show that the theory possesses gauge invariant and diffeomorphism invariant renormalizability to all orders in the loop expansion and the extended BRST symmetry after renormalization is preserved. The advantage of the Sp(2)-method compared to the standard Batalin-Vilkovisky approach is that, in reducible theories, the structure of ghosts and ghosts for ghosts and auxiliary fields is described in terms of irreducible representations of the Sp(2) group. This makes the presentation of solutions to the master equations in more simple and systematic way because they are Sp(2)- scalars.
Energy Technology Data Exchange (ETDEWEB)
Lavrov, Peter M., E-mail: lavrov@tspu.edu.r [Department of Mathematical Analysis, Tomsk State Pedagogical University, Kievskaya St. 60, Tomsk 634061 (Russian Federation)
2011-08-11
The renormalization of general gauge theories on flat and curved space-time backgrounds is considered within the Sp(2)-covariant quantization method. We assume the existence of a gauge-invariant and diffeomorphism invariant regularization. Using the Sp(2)-covariant formalism one can show that the theory possesses gauge-invariant and diffeomorphism invariant renormalizability to all orders in the loop expansion and the extended BRST-symmetry after renormalization is preserved. The advantage of the Sp(2) method compared to the standard Batalin-Vilkovisky approach is that, in reducible theories, the structure of ghosts and ghosts for ghosts and auxiliary fields is described in terms of irreducible representations of the Sp(2) group. This makes the presentation of solutions to the master equations in more simple and systematic way because they are Sp(2)-scalars.
Renormalizing Entanglement Distillation.
Waeldchen, Stephan; Gertis, Janina; Campbell, Earl T; Eisert, Jens
2016-01-15
Entanglement distillation refers to the task of transforming a collection of weakly entangled pairs into fewer highly entangled ones. It is a core ingredient in quantum repeater protocols, which are needed to transmit entanglement over arbitrary distances in order to realize quantum key distribution schemes. Usually, it is assumed that the initial entangled pairs are identically and independently distributed and are uncorrelated with each other, an assumption that might not be reasonable at all in any entanglement generation process involving memory channels. Here, we introduce a framework that captures entanglement distillation in the presence of natural correlations arising from memory channels. Conceptually, we bring together ideas from condensed-matter physics-ideas from renormalization and matrix-product states and operators-with those of local entanglement manipulation, Markov chain mixing, and quantum error correction. We identify meaningful parameter regions for which we prove convergence to maximally entangled states, arising as the fixed points of a matrix-product operator renormalization flow.
Renormalizing Partial Differential Equations
Bricmont, J.; Kupiainen, A.
1994-01-01
In this review paper, we explain how to apply Renormalization Group ideas to the analysis of the long-time asymptotics of solutions of partial differential equations. We illustrate the method on several examples of nonlinear parabolic equations. We discuss many applications, including the stability of profiles and fronts in the Ginzburg-Landau equation, anomalous scaling laws in reaction-diffusion equations, and the shape of a solution near a blow-up point.
Holographic renormalization and supersymmetry
Genolini, Pietro Benetti; Cassani, Davide; Martelli, Dario; Sparks, James
2017-02-01
Holographic renormalization is a systematic procedure for regulating divergences in observables in asymptotically locally AdS spacetimes. For dual boundary field theories which are supersymmetric it is natural to ask whether this defines a supersymmetric renormalization scheme. Recent results in localization have brought this question into sharp focus: rigid supersymmetry on a curved boundary requires specific geometric structures, and general arguments imply that BPS observables, such as the partition function, are invariant under certain deformations of these structures. One can then ask if the dual holographic observables are similarly invariant. We study this question in minimal N = 2 gauged supergravity in four and five dimensions. In four dimensions we show that holographic renormalization precisely reproduces the expected field theory results. In five dimensions we find that no choice of standard holographic counterterms is compatible with supersymmetry, which leads us to introduce novel finite boundary terms. For a class of solutions satisfying certain topological assumptions we provide some independent tests of these new boundary terms, in particular showing that they reproduce the expected VEVs of conserved charges.
DEFF Research Database (Denmark)
Petersen, Dirch Hjorth; Lin, Rong; Hansen, Torben Mikael;
2008-01-01
In this comparative study, the authors demonstrate the relationship/correlation between macroscopic and microscopic four-point sheet resistance measurements on laser annealed ultra-shallow junctions (USJs). Microfabricated cantilever four-point probes with probe pitch ranging from 1.5 to 500 mu m...... have been used to characterize the sheet resistance uniformity of millisecond laser annealed USJs. They verify, both experimentally and theoretically, that the probe pitch of a four-point probe can strongly affect the measured sheet resistance. Such effect arises from the sensitivity (or "spot size......") of an in-line four-point probe. Their study shows the benefit of the spatial resolution of the micro four-point probe technique to characterize stitching effects resulting from the laser annealing process....
Beyond van der Pauw: Novel methods for four-point magnetotransport characterization
Zhou, Wang
In this thesis, the conventional four-point measurement technique and the van der Pauw (vdP) method are systematically investigated in the presence of non-ideal conditions, namely, non-uniform carrier density distribution and absence of ohmic contacts, which are nonetheless commonly encountered in semiconductor characterizations. Upon understanding the challenges in the conventional methods, novel characterization techniques are developed to address these challenges. A longitudinal magnetoresistance asymmetry method was developed to study the carrier density non-uniformity in two-dimensional samples. By analyzing the asymmetric longitudinal magnetoresistance under positive and negative B-fields, an analytical model based on a linear density gradient across the sample was deduced to quantitatively describe the asymmetry. Based on the theoretical model, a practical method was described which enabled one to experimentally measure the density gradient within a single sample. The method requires only measurements of longitudinal resistances R xx and Ryy under both positive and negative B-fields, and equations have been provided to extract both the angle and the magnitude of density gradients from the measured resistances. The method was demonstrated in a GaAs quantum well wafer at cryogenic temperatures and n-GaAs bulk-doped wafer at room temperature. In both systems, the density gradient vectors extracted with our method matched well with the interpolated density gradient vectors estimated from actual density distribution maps as a base comparison set, suggesting that our method can be a universal extension of the vdP method to extract density gradients in various systems. The method also allows one to uncover the true local longitudinal resistivity rhoxx at the center of the sample, which the conventional vdP method cannot describe in the presence of non-uniform densities. The ability to find rhoxx makes it possible to study interesting physics in semiconductors such
Directory of Open Access Journals (Sweden)
Vrabel Robert
2011-01-01
Full Text Available Abstract This paper deals with the existence and asymptotic behavior of the solutions to the singularly perturbed second-order nonlinear differential equations. For example, feedback control problems, such as the steady states of the thermostats, where the controllers add or remove heat, depending upon the temperature detected by the sensors in other places, can be interpreted with a second-order ordinary differential equation subject to a nonlocal four-point boundary condition. Singular perturbation problems arise in the heat transfer problems with large Peclet numbers. We show that the solutions of mathematical model, in general, start with fast transient which is the so-called boundary layer phenomenon, and after decay of this transient they remain close to the solution of reduced problem with an arising new fast transient at the end of considered interval. Our analysis relies on the method of lower and upper solutions.
Energy Technology Data Exchange (ETDEWEB)
Pettersen, Sigurd R., E-mail: sigurd.r.pettersen@ntnu.no, E-mail: jianying.he@ntnu.no; Stokkeland, August Emil; Zhang, Zhiliang; He, Jianying, E-mail: sigurd.r.pettersen@ntnu.no, E-mail: jianying.he@ntnu.no [NTNU Nanomechanical Lab, Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway); Kristiansen, Helge [NTNU Nanomechanical Lab, Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway); Conpart AS, Dragonveien 54, NO-2013 Skjetten (Norway); Njagi, John; Goia, Dan V. [Center for Advanced Materials Processing, Clarkson University, Potsdam, New York 13699-5814 (United States); Redford, Keith [Conpart AS, Dragonveien 54, NO-2013 Skjetten (Norway)
2016-07-25
Micron-sized metal-coated polymer spheres are frequently used as filler particles in conductive composites for electronic interconnects. However, the intrinsic electrical resistivity of the spherical thin films has not been attainable due to deficiency in methods that eliminate the effect of contact resistance. In this work, a four-point probing method using vacuum compatible piezo-actuated micro robots was developed to directly investigate the electric properties of individual silver-coated spheres under real-time observation in a scanning electron microscope. Poly(methyl methacrylate) spheres with a diameter of 30 μm and four different film thicknesses (270 nm, 150 nm, 100 nm, and 60 nm) were investigated. By multiplying the experimental results with geometrical correction factors obtained using finite element models, the resistivities of the thin films were estimated for the four thicknesses. These were higher than the resistivity of bulk silver.
Advanced carrier depth profiling on Si and Ge with micro four-point probe
DEFF Research Database (Denmark)
Clarysse, Trudo; Eyben, Pierre; Parmentier, Brigitte
2008-01-01
In order to reach the ITRS goals for future complementary metal-oxide semiconductor technologies, there is a growing need for the accurate extraction of ultrashallow electrically active dopant (carrier) profiles. In this work, it will be illustrated that this need can be met by the micro four......-point probe (M4PP) tool. M4PP sheet resistance measurements taken along beveled Si and Ge blanket shallow structures will be investigated. From the differential sheet resistance changes, the underlying carrier profile can be reconstructed without the need to rely on a complicated contact modeling, i.e., M4PP...... carrier profiling is an absolute carrier depth profiling technique. On Si, it is found that the more sensitive a structure is to carrier spilling along the bevel, the better the M4PP system performs relative to conventional spreading resistance probe (SRP) due to its much lower probe pressure...
Ultra-shallow junction (USJ) sheet resistance measurements with a non-penetrating four point probe
Benjamin, M. C.; Hillard, R. J.; Borland, J. O.
2005-08-01
An accurate method to measure the four point probe (4PP) sheet resistance (RS) of ultra shallow junction (USJ) Source-Drain Extension structures is described. The method utilizes Elastic Material probes (EM-probes) to form non-penetrating contacts to the silicon surface [R.J. Hillard, P.Y. Hung, William Chism, C. Win Ye, W.H. Howland, L.C. Tan, C.E. Kalnas, Characterization and Metrology for ULSI Technology, AIP Conference proceedings 683 (2003) 802.]. The probe design is kinematic and the force is controlled to ensure elastic deformation of the probe material. The probe material is such that large direct tunneling currents can flow through the native oxide thereby forming a low impedance contact. Sheet resistance measurements on USJ implanted P+/N structures with Secondary Ion Mass Spectroscopy (SIMS) junction depths less than 15 nm have been measured. The method is demonstrated on implanted USJ structures and found to be consistent with expectations.
Dynamics of graphite fiber intercalation: In situ resistivity measurements with a four point probe
Jaworske, D. A.
1984-01-01
The dynamics of ferric chloride intercalation of single graphite fibers were studied, in situ, using a four point dc bridge. Measurements before, during and after the intercalation showed that the intercalation occurred within minutes at 200 C. Changes in fiber resistivity after exposure to air suggested hydration of the graphite intercalation compound. Deintercalation of the ferric chloride was initiated at temperatures in excess of 400 C. cycling the intercalant into and out of the graphite fiber gave no improvements in fiber resistivity. The activation energy of the ferric chloride intercalation reaction was found to be 17 + or - 4 kcal/mol 1 consistent with the concept of a preliminary nucleation step in the intercalation reaction.
Fast and direct measurements of the electrical properties of graphene using micro four-point probes.
Klarskov, M B; Dam, H F; Petersen, D H; Hansen, T M; Löwenborg, A; Booth, T J; Schmidt, M S; Lin, R; Nielsen, P F; Bøggild, P
2011-11-04
We present measurements of the electronic properties of graphene using a repositionable micro four-point probe system, which we show here to have unique advantages over measurements made on lithographically defined devices; namely speed, simplicity and lack of a need to pattern graphene. Measurements are performed in ambient, vacuum and controlled environmental conditions using an environmental scanning electron microscope (SEM). The results are comparable to previous results for microcleaved graphene on silicon dioxide (SiO(2)). We observe a pronounced hysteresis of the charge neutrality point, dependent on the sweep rate of the gate voltage; and environmental measurements provide insight into the sensor application prospects of graphene. The method offers a fast, local and non-destructive technique for electronic measurements on graphene, which can be positioned freely on a graphene flake.
DEFF Research Database (Denmark)
Lacevic, N.; Starr, F. W.; Schrøder, Thomas
2003-01-01
two-point time-dependent density correlation functions, while providing information about the transient "caging" of particles on cooling, are unable to provide sufficiently detailed information about correlated motion and dynamical heterogeneity. Here, we study a four-point, time-dependent density...... simulations of a binary Lennard-Jones mixture approaching the mode coupling temperature from above. We find that the correlations between particles measured by g4(r,t) and S4(q,t) become increasingly pronounced on cooling. The corresponding dynamical correlation length xi4(t) extracted from the small......-q behavior of S4(q,t) provides an estimate of the range of correlated particle motion. We find that xi4(t) has a maximum as a function of time t, and that the value of the maximum of xi4(t) increases steadily from less than one particle diameter to a value exceeding nine particle diameters in the temperature...
DEFF Research Database (Denmark)
Hasegawa, S.; Grey, Francois
2002-01-01
show that this type of conduction is measurable using new types of experimental probes, such as the multi-tip scanning tunnelling microscope and the micro-four-point probe. The resulting electronic transport properties are intriguing, and suggest that semiconductor surfaces should be considered......The electrical properties of semiconductor surfaces have played a decisive role in one of the most important discoveries of the last century, transistors. In the 1940s, the concept of surface states-new electron energy levels characteristic of the surface atoms-was instrumental in the fabrication...... of the first point-contact transistors, and led to the successful fabrication of field-effect transistors. However, to this day, one property of semiconductor surface states remains poorly understood, both theoretically and experimentally. That is the conduction of electrons or holes directly through...
Dynamic Carrying Capacity Analysis of Double-Row Four-Point Contact Ball Slewing Bearing
Directory of Open Access Journals (Sweden)
Yunfeng Li
2015-01-01
Full Text Available Carrying capacity is the most important performance index for slewing bearings. Maximizing the carrying capacity of slewing bearing is one pursuing goal for the bearing designer; this is usually realized by optimizing the design parameters. A method of analyzing the carrying capacity of double-row four-point contact ball slewing bearing by using dynamic carrying capacity surfaces was proposed in this paper. Based on the dynamic load carrying capacity surface of the slewing bearing, the effect of changes of the bearing design parameters, such as axial clearance, raceway groove radius coefficient, and contact angle, on the dynamic carrying capacity of the slewing bearing was researched; the trend and the degree of the effect of the micro changes of the bearing design parameters on the dynamic load carrying capacity of the bearing were discussed, and the results provide the basis for optimizing the design parameter of this type of slewing bearing.
Fast and direct measurements of the electrical properties of graphene using micro four-point probes
DEFF Research Database (Denmark)
Klarskov, Mikkel Buster; Dam, Henrik Friis; Petersen, Dirch Hjorth
2011-01-01
. Measurements are performed in ambient, vacuum and controlled environmental conditions using an environmental scanning electron microscope (SEM). The results are comparable to previous results for microcleaved graphene on silicon dioxide (SiO2). We observe a pronounced hysteresis of the charge neutrality point......We present measurements of the electronic properties of graphene using a repositionable micro four-point probe system, which we show here to have unique advantages over measurements made on lithographically defined devices; namely speed, simplicity and lack of a need to pattern graphene......, dependent on the sweep rate of the gate voltage; and environmental measurements provide insight into the sensor application prospects of graphene. The method offers a fast, local and non-destructive technique for electronic measurements on graphene, which can be positioned freely on a graphene flake....
Four-point Bend Testing of Irradiated Monolithic U-10Mo Fuel
Energy Technology Data Exchange (ETDEWEB)
Rabin, B. H. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lloyd, W. R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schulthess, J. L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wright, J. K. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lind, R. P. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Scott, L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wachs, K. M. [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2015-03-01
This paper presents results of recently completed studies aimed at characterizing the mechanical properties of irradiated U-10Mo fuel in support of monolithic base fuel qualification. Mechanical properties were evaluated in four-point bending. Specimens were taken from fuel plates irradiated in the RERTR-12 and AFIP-6 Mk. II irradiation campaigns, and tests were conducted in the Hot Fuel Examination Facility (HFEF) at Idaho National Laboratory (INL). The monolithic fuel plates consist of a U-10Mo fuel meat covered with a Zr diffusion barrier layer fabricated by co-rolling, clad in 6061 Al using a hot isostatic press (HIP) bonding process. Specimens exhibited nominal (fresh) fuel meat thickness ranging from 0.25 mm to 0.64 mm, and fuel plate average burnup ranged from approximately 0.4 x 1021 fissions/cm^{3} to 6.0 x 1021 fissions/cm^{3}. After sectioning the fuel plates, the 6061 Al cladding was removed by dissolution in concentrated NaOH. Pre- and post-dissolution dimensional inspections were conducted on test specimens to facilitate accurate analysis of bend test results. Four-point bend testing was conducted on the HFEF Remote Load Frame at a crosshead speed of 0.1 mm/min using custom-designed test fixtures and calibrated load cells. All specimens exhibited substantially linear elastic behavior and failed in a brittle manner. The influence of burnup on the observed slope of the stress-strain curve and the calculated fracture strength is discussed.
Spinfoam Cosmology with the Proper Vertex
Vilensky, Ilya
2017-01-01
A modification of the EPRL vertex amplitude in the spin-foam framework of quantum gravity - so-called ``proper vertex amplitude'' - has been developed to enable correct semi-classical behavior to conform to the classical Regge calculus. The proper vertex amplitude is defined by projecting to the single gravitational sector. The amplitude is recast into an exponentiated form and we derive the asymptotic form of the projector part of the action. This enables us to study the asymptotics of the proper vertex by applying extended stationary phase methods. We use the proper vertex amplitude to investigate transition amplitudes between coherent quantum boundary states of cosmological geometries. In particular, Hartle-Hawking no-boundary states are computed in the proper vertex framework. We confirm that in the classical limit the Hartle-Hawking wavefunction satisfies the Hamiltonian constraint. Partly supported by NSF grants PHY-1205968 and PHY-1505490.
The LHCb Vertex Locator performance and Vertex Locator upgrade
INSPIRE-00259789
2012-01-01
LHCb is an experiment dedicated to the study of new physics in the decays of beauty and charm hadrons at the Large Hadron Collider (LHC) at CERN. The Vertex Locator (VELO) is the silicon detector surrounding the LHCb interaction point. The detector operates in a severe and highly non-uniform radiation environment. The small pitch and analogue readout result in a best single hit precision of 4 $\\rm \\mu$m. The upgrade of the LHCb experiment, planned for 2018, will transform the entire readout to a trigger-less system operating at 40 MHz event rate. The vertex detector will have to cope with radiation levels up to 10$^{16}$ 1 MeV$\\rm n_{eq}/cm^2$, more than an order of magnitude higher than those expected at the current experiment. A solution is under development with a pixel detector, based on the Timepix/Medipix family of chips with 55 x 55 $\\rm \\mu m$ pixels. In addition a micro-strip solution is also under development, with finer pitch, higher granularity and lower mass than the current detector. The current...
AUTHOR|(SzGeCERN)734627
2015-01-01
A vertex-detector concept is under development for the proposed multi-TeV linear e+e- Compact Linear Collider (CLIC). To perform precision physics measurements in a chal- lenging environment, the CLIC vertex detector pushes the technological requirements to the limits. This paper reviews the requirements for the CLIC vertex detector and gives an over- view of recent R&D achievements in the domains of sensor, readout, powering and cooling.
Alipour Tehrani, Niloufar
2016-07-01
A vertex detector concept is under development for the proposed multi-TeV linear e+e- Compact Linear Collider (CLIC). To perform precision physics measurements in a challenging environment, the CLIC vertex detector pushes the technological requirements to the limits. This paper reviews the requirements for the CLIC vertex detector and gives an overview of recent R&D achievements in the domains of sensor, readout, powering and cooling.
The SUPERB silicon vertex tracker
Energy Technology Data Exchange (ETDEWEB)
Forti, F., E-mail: Francesco.Forti@pi.infn.it [INFN-Pisa and Universita di Pisa (Italy); Avanzini, C.; Batignani, G.; Bettarini, S.; Bosi, F.; Calderini, G.; Ceccanti, M.; Cenci, R.; Cervelli, A.; Crescioli, F.; Dell' Orso, M.; Giannetti, P.; Giorgi, M.A. [INFN-Pisa and Universita di Pisa (Italy); Lusiani, A. [Scuola Normale Superiore and INFN-Pisa (Italy); Gregucci, S.; Mammini, P.; Marchiori, G.; Massa, M.; Morsani, F.; Neri, N. [INFN-Pisa and Universita di Pisa (Italy)
2011-04-21
The SUPERB asymmetric e{sup +}e{sup -} collider, to be built near the INFN National Frascati Laboratory in Italy, has been designed to deliver a luminosity greater than 10{sup 36} cm{sup -2} s{sup -1} with moderate beam currents, allowing precision measurements in the flavour sector sensitive to New Physics. The conceptual design of the Silicon Vertex Tracker for the SUPERB Detector is presented, based on double-sided silicon strip detectors for the outer layers, with the addition of an innermost Layer 0 close to the interaction point, with low material budget and capable of sustaining a background rate of several MHz/cm{sup 2}.
The CDF Silicon Vertex Detector
Energy Technology Data Exchange (ETDEWEB)
Tkaczyk, S.; Carter, H.; Flaugher, B. [and others
1993-09-01
A silicon strip vertex detector was designed, constructed and commissioned at the CDF experiment at the Tevatron collider at Fermilab. The mechanical design of the detector, its cooling and monitoring are presented. The front end electronics employing a custom VLSI chip, the readout electronics and various components of the SVX system are described. The system performance and the experience with the operation of the detector in the radiation environment are discussed. The device has been taking colliding beams data since May of 1992, performing at its best design specifications and enhancing the physics program of CDF.
Renormalization group flow equations from the 4PI equations of motion
Carrington, M E
2013-01-01
The 4PI effective action provides a a hierarchy of integral equations which have the form of Bethe-Salpeter equations. The vertex functions obtained from these equations can be used to truncate the exact renormalization group flow equations. This truncation has the property that the flow is a total derivative with respect to the flow parameter and is equivalent to solving the nPI equations of motion. This result establishes a direct connection between two non-perturbative methods.
A new construction for vertex decomposable graphs
Directory of Open Access Journals (Sweden)
Nasser Hajisharifi
2016-09-01
Full Text Available Let G be a finite simple graph on the vertex set V(G and let S⊆V(G. Adding a whisker to G at x means adding a new vertex y and edge xy to G where x∈V(G. The graph G∪W(S is obtained from G by adding a whisker to every vertex of S. We prove that if G∖S is either a graph with no chordless cycle of length other than 3 or 5, chordal graph or C5, then G∪W(S is a vertex decomposable graph.
Renormalization of the QED of second order spin 1/2 fermions
Angeles-Martinez, Rene
2011-01-01
In this work we study the renormalization of the electrodynamics of spin 1/2 fermions in the Poincare projector formalism which is second order in the derivatives of the fields. We analyze the degree of superficial divergence of the vertex functions and calculate 2- and 3-point vertex functions at one-loop level. It is shown that these functions are renormalizable independently of the value of the gyromagnetic factor g which is a free parameter of the theory. We find a photon propagator and a running coupling constant alpha (q^2) that depends on the value of g. In general, the magnetic moment form factor of the one-loop Feynman diagrams contributions to the fermion-fermion-gamma vertex function contains a divergence associated to g. This requires the coupling g to be renormalized. Imposing as the renormalization condition g(q^2=0) to be the measured gyromagnetic factor at low energy we obtain a one loop finite correction Delta{g}=g alpha/2pi. For a particle with g=2 the divergence associated to this coupling ...
Renormalization on noncommutative torus
D'Ascanio, D; Vassilevich, D V
2016-01-01
We study a self-interacting scalar $\\varphi^4$ theory on the $d$-dimensional noncommutative torus. We determine, for the particular cases $d=2$ and $d=4$, the nonlocal counterterms required by one-loop renormalization. We discuss higher loops in two dimensions and two-loop contributions to the self-energy in four dimensions. Our analysis points towards the absence of any problems related to the UV/IR mixing and thus to renormalizability of the theory. However, we find another potentially troubling phenomenon which is a wild behavior of the two-point amplitude as a function of the noncommutativity matrix $\\theta$.
Renormalization of composite operators
Polonyi, J
2001-01-01
The blocked composite operators are defined in the one-component Euclidean scalar field theory, and shown to generate a linear transformation of the operators, the operator mixing. This transformation allows us to introduce the parallel transport of the operators along the RG trajectory. The connection on this one-dimensional manifold governs the scale evolution of the operator mixing. It is shown that the solution of the eigenvalue problem of the connection gives the various scaling regimes and the relevant operators there. The relation to perturbative renormalization is also discussed in the framework of the $\\phi^3$ theory in dimension $d=6$.
Battle, G A
1999-01-01
WAVELETS AND RENORMALIZATION describes the role played by wavelets in Euclidean field theory and classical statistical mechanics. The author begins with a stream-lined introduction to quantum field theory from a rather basic point of view. Functional integrals for imaginary-time-ordered expectations are introduced early and naturally, while the connection with the statistical mechanics of classical spin systems is introduced in a later chapter.A vastly simplified (wavelet) version of the celebrated Glimm-Jaffe construction of the F 4 3 quantum field theory is presented. It is due to Battle and
Renormalization on noncommutative torus
Energy Technology Data Exchange (ETDEWEB)
D' Ascanio, D.; Pisani, P. [Universidad Nacional de La Plata, Instituto de Fisica La Plata-CONICET, La Plata (Argentina); Vassilevich, D.V. [Universidade Federal do ABC, CMCC, Santo Andre, SP (Brazil); Tomsk State University, Department of Physics, Tomsk (Russian Federation)
2016-04-15
We study a self-interacting scalar φ{sup 4} theory on the d-dimensional noncommutative torus. We determine, for the particular cases d = 2 and d = 4, the counterterms required by one-loop renormalization. We discuss higher loops in two dimensions and two-loop contributions to the self-energy in four dimensions. Our analysis points toward the absence of any problems related to the ultraviolet/infrared mixing and thus to renormalizability of the theory. However, we find another potentially troubling phenomenon which is a wild behavior of the two-point amplitude as a function of the noncommutativity matrix θ. (orig.)
Renormalization on noncommutative torus
D'Ascanio, D.; Pisani, P.; Vassilevich, D. V.
2016-04-01
We study a self-interacting scalar \\varphi ^4 theory on the d-dimensional noncommutative torus. We determine, for the particular cases d=2 and d=4, the counterterms required by one-loop renormalization. We discuss higher loops in two dimensions and two-loop contributions to the self-energy in four dimensions. Our analysis points toward the absence of any problems related to the ultraviolet/infrared mixing and thus to renormalizability of the theory. However, we find another potentially troubling phenomenon which is a wild behavior of the two-point amplitude as a function of the noncommutativity matrix θ.
Renormalized parameters and perturbation theory in dynamical mean-field theory for the Hubbard model
Hewson, A. C.
2016-11-01
We calculate the renormalized parameters for the quasiparticles and their interactions for the Hubbard model in the paramagnetic phase as deduced from the low-energy Fermi-liquid fixed point using the results of a numerical renormalization-group calculation (NRG) and dynamical mean-field theory (DMFT). Even in the low-density limit there is significant renormalization of the local quasiparticle interaction U ˜, in agreement with estimates based on the two-particle scattering theory of J. Kanamori [Prog. Theor. Phys. 30, 275 (1963), 10.1143/PTP.30.275]. On the approach to the Mott transition we find a finite ratio for U ˜/D ˜ , where 2 D ˜ is the renormalized bandwidth, which is independent of whether the transition is approached by increasing the on-site interaction U or on increasing the density to half filling. The leading ω2 term in the self-energy and the local dynamical spin and charge susceptibilities are calculated within the renormalized perturbation theory (RPT) and compared with the results calculated directly from the NRG-DMFT. We also suggest, more generally from the DMFT, how an approximate expression for the q ,ω spin susceptibility χ (q ,ω ) can be derived from repeated quasiparticle scattering with a local renormalized scattering vertex.
Renormalization group for evolving networks.
Dorogovtsev, S N
2003-04-01
We propose a renormalization group treatment of stochastically growing networks. As an example, we study percolation on growing scale-free networks in the framework of a real-space renormalization group approach. As a result, we find that the critical behavior of percolation on the growing networks differs from that in uncorrelated networks.
Directory of Open Access Journals (Sweden)
E. A. Lucek
Full Text Available The Cluster spacecraft have returned the first simultaneous four-point measurements of the magnetosheath. We present an analysis of data recorded on 10 November 2000, when the four spacecrafts observed an interval of strong mirrorlike activity. Correlation analysis between spacecraft pairs is used to examine the scale size of the mirror structures in three dimensions. Two examples are presented which suggest that the scale size of mirror structures is ~ 1500–3000 km along the flow direction, and shortest along the magnetopause normal (< 600 km, which, in this case, is approximately perpendicular to both the mean magnetic field and the magnetosheath flow vector. Variations on scales of ~ 750–1000 km are found along the maximum variance direction. The level of correlation in this direction, however, and the time lag observed, are found to be variable. These first results suggest that variations occur on scales of the order of the spacecraft separation ( ~ 1000 km in at least two directions, but analysis of further examples and a statistical survey of structures observed with different magnetic field orientations and tetrahedral configurations will enable us to describe more fully the size and orientation of mirror structures.
Key words. Magnetosphenic physics (magnetosheath; plasma waves and instabilities
The Complete Four-Loop Four-Point Amplitude in N
Energy Technology Data Exchange (ETDEWEB)
Bern, Z.; Carrasco, J.J.M.; /UCLA; Dixon, Lance J.; /SLAC /CERN; Johansson, H.; /Saclay, SPhT; Roiban, R.; /Penn State U.
2010-08-25
We present the complete four-loop four-point amplitude in N = 4 super-Yang-Mills theory, for a general gauge group and general D-dimensional covariant kinematics, and including all non-planar contributions. We use the method of maximal cuts - an efficient application of the unitarity method - to construct the result in terms of 50 four-loop integrals. We give graphical rules, valid in D-dimensions, for obtaining various non-planar contributions from previously-determined terms. We examine the ultraviolet behavior of the amplitude near D = 11/2. The non-planar terms are as well-behaved in the ultraviolet as the planar terms. However, in the color decomposition of the three- and four-loop amplitude for an SU(N{sub c}) gauge group, the coefficients of the double-trace terms are better behaved in the ultraviolet than are the single-trace terms. The results from this paper were an important step toward obtaining the corresponding amplitude in N = 8 supergravity, which confirmed the existence of cancellations beyond those needed for ultraviolet finiteness at four loops in four dimensions. Evaluation of the loop integrals near D = 4 would permit tests of recent conjectures and results concerning the infrared behavior of four-dimensional massless gauge theory.
Li, Bing Qiuyi; Einstein, Herbert H.
2017-09-01
We present an experimental study in which a pre-notched specimen of Barre Granite was subjected to four point bending under crack mouth opening displacement control. The experimental observations consisted of load-displacement measurements, acoustic emissions, and photography on a macroscopic ( cm) as well as microscopic ( μm) scale. These observations were compared and analysed to better understand process zone development and crack propagation. Load-displacement data showed that the load reaches its maximum at crack initiation, and the machine input work is constant while the crack propagates. AE moment magnitudes between Mw = -6 to -10 were observed, and focal mechanisms consisted of both shear and tensile components. During process zone development, AE formed a large cloud of events located near the notch tip and then tended to occur away from the notch tip as the crack propagated. Image analysis at the microscopic scale showed that microcracks formed and coalesced during process zone development; specifically, the microcracks initiated in tension and then propagated as a series of en-echelon cracks. In general, the synthesis of the three observations showed that a wider bulb of activity at lower energy tended to occur during process zone development, while crack propagation tended to be more spatially concentrated and contained higher energy.
Yoshimoto, T.; Matsuo, T.
2017-05-01
To evaluate hydrogen embrittlement, the following two types of testing method are available: (i) testing in high-pressure hydrogen gas environment and (ii) testing in ambient air using hydrogen precharged specimen. Testing in high-pressure hydrogen gas environment is technically difficult and expensive because high-pressure gas equipments, such as high-pressure vessel and pipe, have to be installed in the laboratory. On the other hand, in the case of precharging method, outgassing of hydrogen from the specimen occurs during the test. Therefore, hydrogen embrittlement can hardly be evaluated properly, especially, in long-term testing such as high cycle fatigue test at low frequency. In this study, to effectively evaluate the hydrogen embrittlement in fatigue, an experimental method, which was the four-point bending fatigue test system with a mechanism of internal circulation of hydrogen-charging solution in a pipe specimen, was developed. By using this method, the fatigue crack growth properties in the presence of hydrogen were investigated at frequencies of 0.05 Hz and 1 Hz.
Quantum toroidal algebras and their vertex representations
Saitô, Y
1996-01-01
We construct the vertex representations of the quantum toroidal algebras $U_q({\\frak {sl}}_{n+1,tor})$. In the classical case the vertex representations are not irreducible. However in the quantum case they are irreducible. For n=1, we construct a set of finitely many generators of $U_q({\\frak {sl}}_{2,tor})$.
New vertex reconstruction algorithms for CMS
Frühwirth, R; Prokofiev, Kirill; Speer, T.; Vanlaer, P.; Chabanat, E.; Estre, N.
2003-01-01
The reconstruction of interaction vertices can be decomposed into a pattern recognition problem (``vertex finding'') and a statistical problem (``vertex fitting''). We briefly review classical methods. We introduce novel approaches and motivate them in the framework of high-luminosity experiments like at the LHC. We then show comparisons with the classical methods in relevant physics channels
Vertex Reconstruction in ATLAS Run II
Zhang, Matt; The ATLAS collaboration
2016-01-01
Vertex reconstruction is the process of taking reconstructed tracks and using them to determine the locations of proton collisions. In this poster we present the performance of our current vertex reconstruction algorithm, and look at investigations into potential improvements from a new seed finding method.
Cluster observes the Earth’s magnetopause: coordinated four-point magnetic field measurements
Directory of Open Access Journals (Sweden)
M. W. Dunlop
Full Text Available The four-spacecraft Cluster mission has provided high-time resolution measurements of the magnetic field from closely maintained separation distances (200–600 km. Four-point coverage of the Earth’s magnetopause began on the 9 and 10 November 2000 when all spacecraft first exited the dusk-side magnetosphere at about 19:00 LT, providing extensive coverage of the near flank magnetosheath and magnetopause boundary layer on re-entry to the magnetosphere. The traversals on this occasion were caused by the arrival of an intense CME at the Earth, which produced a large compression of the magnetopause and high magnetic activity. The magnetopause traversals represent an unprecedented data set, allowing detailed analysis of the local magnetic structure (gradients and dynamics of the magnetopause boundary. By performing minimum variance analysis (MVA on the magnetic field data from all four spacecraft, we demonstrate that the magnetopause was planar on the scale of the spacecraft separation scales and that the transverse scale size of the magnetopause boundary layer was 1000–1100 km. We also show that the motion of the boundary (defined by the magnetic shear at the current layer, is changing over the sequence of spacecraft crossings so that acceleration of the magnetopause can be very high in this region of the magnetosphere. Indeed, the magnetopause speed reaches the order of 300 km/s in response to the arrival of the interplanetary shock. Using MVA coordinates, we have identified a number of magnetospheric and magnetosheath FTE signatures, which are sampled simultaneously by all spacecraft at different distances from and on either side of the magnetopause. The signatures show a variation of scale with distance from the boundary.
Key words. Magnetospheric physics (magnetopause, cusp and boundary layers Space plasma physics (discontinuities; magnetic reconnection
A Systems Engineering Analysis of Three-Point and Four-Point Wind Turbine Drivetrain Configurations
Energy Technology Data Exchange (ETDEWEB)
Guo, Yi; Parsons, Tyler; Dykes, Katherine; King, Ryan N.
2017-03-01
This study compares the impact of drivetrain configuration on the mass and capital cost of a series of wind turbines ranging from 1.5 MW to 5.0 MW power ratings for both land-based and offshore applications. The analysis is performed with a new physics-based drivetrain analysis and sizing tool, Drive Systems Engineering (DriveSE), which is part of the Wind-Plant Integrated System Design & Engineering Model. DriveSE uses physics-based relationships to size all major drivetrain components according to given rotor loads simulated based on International Electrotechnical Commission design load cases. The model's sensitivity to input loads that contain a high degree of variability was analyzed. Aeroelastic simulations are used to calculate the rotor forces and moments imposed on the drivetrain for each turbine design. DriveSE is then used to size all of the major drivetrain components for each turbine for both three-point and four-point configurations. The simulation results quantify the trade-offs in mass and component costs for the different configurations. On average, a 16.7% decrease in total nacelle mass can be achieved when using a three-point drivetrain configuration, resulting in a 3.5% reduction in turbine capital cost. This analysis is driven by extreme loads and does not consider fatigue. Thus, the effects of configuration choices on reliability and serviceability are not captured. However, a first order estimate of the sizing, dimensioning and costing of major drivetrain components are made which can be used in larger system studies which consider trade-offs between subsystems such as the rotor, drivetrain and tower.
Fifty years of the renormalization group
Shirkov, D V
2001-01-01
Renormalization was the breakthrough that made quantum field theory respectable in the late 1940s. Since then, renormalization procedures, particularly the renormalization group method, have remained a touchstone for new theoretical developments. This work relates the history of the renormalization group. (17 refs).
Renormalizing an initial state
Collins, Hael; Vardanyan, Tereza
2014-01-01
The intricate machinery of perturbative quantum field theory has largely been devoted to the 'dynamical' side of the theory: simple states are evolved in complicated ways. This article begins to address this lopsided treatment. Although it is rarely possible to solve for the eigenstates of an interacting theory exactly, a general state and its evolution can nonetheless be constructed perturbatively in terms of the propagators and structures defined with respect to the free theory. The detailed form of the initial state in this picture is fixed by imposing suitable `renormalization conditions' on the Green's functions. This technique is illustrated with an example drawn from inflation, where the presence of nonrenormalizable operators and where an expansion that naturally couples early times with short distances make the ability to start the theory at a finite initial time especially desirable.
Practical Algebraic Renormalization
Grassi, P A; Steinhauser, M
1999-01-01
A practical approach is presented which allows the use of a non-invariant regularization scheme for the computation of quantum corrections in perturbative quantum field theory. The theoretical control of algebraic renormalization over non-invariant counterterms is translated into a practical computational method. We provide a detailed introduction into the handling of the Slavnov-Taylor and Ward-Takahashi identities in the Standard Model both in the conventional and the background gauge. Explicit examples for their practical derivation are presented. After a brief introduction into the Quantum Action Principle the conventional algebraic method which allows for the restoration of the functional identities is discussed. The main point of our approach is the optimization of this procedure which results in an enormous reduction of the calculational effort. The counterterms which have to be computed are universal in the sense that they are independent of the regularization scheme. The method is explicitly illustra...
Renormalized Volumes with Boundary
Gover, A Rod
2016-01-01
We develop a general regulated volume expansion for the volume of a manifold with boundary whose measure is suitably singular along a separating hypersurface. The expansion is shown to have a regulator independent anomaly term and a renormalized volume term given by the primitive of an associated anomaly operator. These results apply to a wide range of structures. We detail applications in the setting of measures derived from a conformally singular metric. In particular, we show that the anomaly generates invariant (Q-curvature, transgression)-type pairs for hypersurfaces with boundary. For the special case of anomalies coming from the volume enclosed by a minimal hypersurface ending on the boundary of a Poincare--Einstein structure, this result recovers Branson's Q-curvature and corresponding transgression. When the singular metric solves a boundary version of the constant scalar curvature Yamabe problem, the anomaly gives generalized Willmore energy functionals for hypersurfaces with boundary. Our approach ...
Gutzwiller renormalization group
Lanatà, Nicola; Yao, Yong-Xin; Deng, Xiaoyu; Wang, Cai-Zhuang; Ho, Kai-Ming; Kotliar, Gabriel
2016-01-01
We develop a variational scheme called the "Gutzwiller renormalization group" (GRG), which enables us to calculate the ground state of Anderson impurity models (AIM) with arbitrary numerical precision. Our method exploits the low-entanglement property of the ground state of local Hamiltonians in combination with the framework of the Gutzwiller wave function and indicates that the ground state of the AIM has a very simple structure, which can be represented very accurately in terms of a surprisingly small number of variational parameters. We perform benchmark calculations of the single-band AIM that validate our theory and suggest that the GRG might enable us to study complex systems beyond the reach of the other methods presently available and pave the way to interesting generalizations, e.g., to nonequilibrium transport in nanostructures.
Gies, Holger; Jaeckel, Joerg
2004-09-01
We investigate textbook QED in the framework of the exact renormalization group. In the strong-coupling region, we study the influence of fluctuation-induced photonic and fermionic self-interactions on the nonperturbative running of the gauge coupling. Our findings confirm the triviality hypothesis of complete charge screening if the ultraviolet cutoff is sent to infinity. Though the Landau pole does not belong to the physical coupling domain owing to spontaneous chiral-symmetry-breaking (χSB), the theory predicts a scale of maximal UV extension of the same order as the Landau pole scale. In addition, we verify that the χSB phase of the theory which is characterized by a light fermion and a Goldstone boson also has a trivial Yukawa coupling.
Renormalization Group Tutorial
Bell, Thomas L.
2004-01-01
Complex physical systems sometimes have statistical behavior characterized by power- law dependence on the parameters of the system and spatial variability with no particular characteristic scale as the parameters approach critical values. The renormalization group (RG) approach was developed in the fields of statistical mechanics and quantum field theory to derive quantitative predictions of such behavior in cases where conventional methods of analysis fail. Techniques based on these ideas have since been extended to treat problems in many different fields, and in particular, the behavior of turbulent fluids. This lecture will describe a relatively simple but nontrivial example of the RG approach applied to the diffusion of photons out of a stellar medium when the photons have wavelengths near that of an emission line of atoms in the medium.
Tensor Network Renormalization.
Evenbly, G; Vidal, G
2015-10-30
We introduce a coarse-graining transformation for tensor networks that can be applied to study both the partition function of a classical statistical system and the Euclidean path integral of a quantum many-body system. The scheme is based upon the insertion of optimized unitary and isometric tensors (disentanglers and isometries) into the tensor network and has, as its key feature, the ability to remove short-range entanglement or correlations at each coarse-graining step. Removal of short-range entanglement results in scale invariance being explicitly recovered at criticality. In this way we obtain a proper renormalization group flow (in the space of tensors), one that in particular (i) is computationally sustainable, even for critical systems, and (ii) has the correct structure of fixed points, both at criticality and away from it. We demonstrate the proposed approach in the context of the 2D classical Ising model.
Wave function and CKM renormalization
Espriu, Doménec
2002-01-01
In this presentation we clarify some aspects of the LSZ formalism and wave function renormalization for unstable particles in the presence of electroweak interactions when mixing and CP violation are considered. We also analyze the renormalization of the CKM mixing matrix which is closely related to wave function renormalization. The effects due to the electroweak radiative corrections that are described in this work are small, but they will need to be considered when the precision in the measurement of the charged current sector couplings reaches the 1% level. The work presented here is done in collaboration with Julian Manzano and Pere Talavera.
Tensor Network Renormalization Yields the Multiscale Entanglement Renormalization Ansatz
Evenbly, G.; Vidal, G.
2015-11-01
We show how to build a multiscale entanglement renormalization ansatz (MERA) representation of the ground state of a many-body Hamiltonian H by applying the recently proposed tensor network renormalization [G. Evenbly and G. Vidal, Phys. Rev. Lett. 115, 180405 (2015)] to the Euclidean time evolution operator e-β H for infinite β . This approach bypasses the costly energy minimization of previous MERA algorithms and, when applied to finite inverse temperature β , produces a MERA representation of a thermal Gibbs state. Our construction endows tensor network renormalization with a renormalization group flow in the space of wave functions and Hamiltonians (and not merely in the more abstract space of tensors) and extends the MERA formalism to classical statistical systems.
Renormalization Group Invariance and Optimal QCD Renormalization Scale-Setting
Wu, Xing-Gang; Wang, Sheng-Quan; Fu, Hai-Bing; Ma, Hong-Hao; Brodsky, Stanley J; Mojaza, Matin
2014-01-01
A valid prediction from quantum field theory for a physical observable should be independent of the choice of renormalization scheme -- this is the primary requirement of renormalization group invariance (RGI). Satisfying scheme invariance is a challenging problem for perturbative QCD (pQCD), since truncated perturbation series do not automatically satisfy the requirements of the renormalization group. Two distinct approaches for satisfying the RGI principle have been suggested in the literature. One is the "Principle of Maximum Conformality" (PMC) in which the terms associated with the $\\beta$-function are absorbed into the scale of the running coupling at each perturbative order; its predictions are scheme and scale independent at every finite order. The other approach is the "Principle of Minimum Sensitivity" (PMS), which is based on local RGI; the PMS approach determines the optimal renormalization scale by requiring the slope of the approximant of an observable to vanish. In this paper, we present a deta...
Tensor Network Renormalization Yields the Multiscale Entanglement Renormalization Ansatz.
Evenbly, G; Vidal, G
2015-11-13
We show how to build a multiscale entanglement renormalization ansatz (MERA) representation of the ground state of a many-body Hamiltonian H by applying the recently proposed tensor network renormalization [G. Evenbly and G. Vidal, Phys. Rev. Lett. 115, 180405 (2015)] to the Euclidean time evolution operator e(-βH) for infinite β. This approach bypasses the costly energy minimization of previous MERA algorithms and, when applied to finite inverse temperature β, produces a MERA representation of a thermal Gibbs state. Our construction endows tensor network renormalization with a renormalization group flow in the space of wave functions and Hamiltonians (and not merely in the more abstract space of tensors) and extends the MERA formalism to classical statistical systems.
Forwood, M R; Bennett, M B; Blowers, A R; Nadorfi, R L
1998-09-01
We modified the noninvasive, in vivo technique for strain application in the tibiae of rats (Turner et al., Bone 12:73-79, 1991). The original model applies four-point bending to right tibiae via an open-loop, stepper-motor-driven spring linkage. Depending on the magnitude of applied load, the model produces new bone formation at periosteal (Ps) or endocortical surfaces (Ec.S). Due to the spring linkage, however, the range of frequencies at which loads can be applied is limited. The modified system replaces this design with an electromagnetic vibrator. A load transducer in series with the loading points allows calibration, the loaders' position to be adjusted, and cyclic loading completed under load control as a closed servo-loop. Two experiments were conducted to validate the modified system: (1) a strain gauge was applied to the lateral surface of the right tibia of 5 adult female rats and strains measured at applied loads from 10 to 60 N; and (2) the bone formation response was determined in 28 adult female Sprague-Dawley rats. Loading was applied as a haversine wave with a frequency of 2 Hz for 18 sec, every second day for 10 days. Peak bending loads were applied at 33, 40, 52, and 64 N, and a sham-loading group was included at 64 N. Strains in the tibiae were linear between 10 and 60 N, and the average peak strain at the Ps.S at 60 N was 2664 +/- 250 microstrain, consistent with the results of Turner's group. Lamellar bone formation was stimulated at the Ec.S by applied bending, but not by sham loading. Bending strains above a loading threshold of 40 N increased Ec lamellar bone formation rate, bone forming surface, and mineral apposition rate with a dose response similar to that reported by Turner et al. (J Bone Miner Res 9:87-97, 1994). We conclude that the modified loading system offers precision for applied loads of between 0 and 70 N, versatility in the selection of loading rates up to 20 Hz, and a reproducible bone formation response in the rat tibia
Recursively arbitrarily vertex-decomposable suns
Directory of Open Access Journals (Sweden)
Olivier Baudon
2011-01-01
Full Text Available A graph \\(G = (V,E\\ is arbitrarily vertex decomposable if for any sequence \\(\\tau\\ of positive integers adding up to \\(|V|\\, there is a sequence of vertex-disjoint subsets of \\(V\\ whose orders are given by \\(\\tau\\, and which induce connected graphs. The aim of this paper is to study the recursive version of this problem on a special class of graphs called suns. This paper is a complement of [O. Baudon, F. Gilbert, M. Woźniak, Recursively arbitrarily vertex-decomposable graphs, research report, 2010].
DEPFET Vertex Detectors: Status and Plans
Simon, Frank
2010-01-01
DEPFET active pixel sensors are a well-developed technology for vertex detectors at future colliders. Extensive test beam campaigns have proven the excellent performance of these devices, and their radiation hardness has been thoroughly tested. For the Belle-II experiment at the SuperKEKB collider, a new vertex detector based on DEPFET technology is being developed, using sensors thinned down to 75 \\mu m. We give an overview over recent results with test devices using ILC pixel geometries as well as the concepts and challenges for the Belle-II pixel vertex tracker and discuss how the R&D for the ILC VXD can take advantage of these developments.
Vertex finding with deformable templates at LHC
Energy Technology Data Exchange (ETDEWEB)
Stepanov, N. [European Organization for Nuclear Research, Geneva (Switzerland); Khanov, A. [European Organization for Nuclear Research, Geneva (Switzerland)
1997-04-11
We present a novel vertex finding technique. The task is formulated as a discrete-continuous optimisation problem in a way similar to the deformable templates approach for the track finding. Unlike the track finding problem, ``elastic hedgehogs`` rather than elastic arms are used as deformable templates. They are initialised by a set of procedures which provide zero level approximation for vertex positions and track parameters at the vertex point. The algorithm was evaluated using the simulated events for the LHC CMS detector and demonstrated good performance. (orig.).
A test of bosonization at the level of four-point functions in Chern-Simons vector models
Bedhotiya, Akshay
2015-01-01
We study four-point functions in Chern-Simons vector models in the large $N$ limit. We compute the four-point function of the scalar primary to all orders in the `t Hooft coupling $\\lambda=N/k$ in $U(N)_k$ Chern-Simons theory coupled to a fundamental fermion, in both the critical and non-critical theory, for a particular case of the external momenta. These theories cover the entire 3-parameter "quasi-boson" and 2-parameter "quasi-fermion" families of 3-dimensional quantum field theories with a slightly-broken higher spin symmetry. Our results are consistent with the celebrated bosonization duality, as we explicitly verify by calculating four-point functions in the free critical and non-critical bosonic theories.
Renormalization automated by Hopf algebra
Broadhurst, D J
1999-01-01
It was recently shown that the renormalization of quantum field theory is organized by the Hopf algebra of decorated rooted trees, whose coproduct identifies the divergences requiring subtraction and whose antipode achieves this. We automate this process in a few lines of recursive symbolic code, which deliver a finite renormalized expression for any Feynman diagram. We thus verify a representation of the operator product expansion, which generalizes Chen's lemma for iterated integrals. The subset of diagrams whose forest structure entails a unique primitive subdivergence provides a representation of the Hopf algebra ${\\cal H}_R$ of undecorated rooted trees. Our undecorated Hopf algebra program is designed to process the 24,213,878 BPHZ contributions to the renormalization of 7,813 diagrams, with up to 12 loops. We consider 10 models, each in 9 renormalization schemes. The two simplest models reveal a notable feature of the subalgebra of Connes and Moscovici, corresponding to the commutative part of the Hopf ...
Chaotic renormalization-group trajectories
DEFF Research Database (Denmark)
Damgaard, Poul H.; Thorleifsson, G.
1991-01-01
, or in regions where the renormalization-group flow becomes chaotic. We present some explicit examples of these phenomena for the case of a Lie group valued spin-model analyzed by means of a variational real-space renormalization group. By directly computing the free energy of these models around the parameter......Under certain conditions, the renormalization-group flow of models in statistical mechanics can change dramatically under just very small changes of given external parameters. This can typically occur close to bifurcations of fixed points, close to the complete disappearance of fixed points...... regions in which such nontrivial modifications of the renormalization-group flow occur, we can extract the physical consequences of these phenomena....
Differential renormalization of gauge theories
Energy Technology Data Exchange (ETDEWEB)
Aguila, F. del; Perez-Victoria, M. [Dept. de Fisica Teorica y del Cosmos, Universidad de Granada, Granada (Spain)
1998-10-01
The scope of constrained differential renormalization is to provide renormalized expressions for Feynman graphs, preserving at the same time the Ward identities of the theory. It has been shown recently that this can be done consistently at least to one loop for Abelian and non-Abelian gauge theories. We briefly review these results, evaluate as an example the gluon self energy in both coordinate and momentum space, and comment on anomalies. (author) 9 refs, 1 fig., 1 tab
Holographic renormalization in teleparallel gravity
Energy Technology Data Exchange (ETDEWEB)
Krssak, Martin [Universidade Estadual Paulista, Instituto de Fisica Teorica, Sao Paulo, SP (Brazil)
2017-01-15
We consider the problem of IR divergences of the action in the covariant formulation of teleparallel gravity in asymptotically Minkowski spacetimes. We show that divergences are caused by inertial effects and can be removed by adding an appropriate surface term, leading to the renormalized action. This process can be viewed as a teleparallel analog of holographic renormalization. Moreover, we explore the variational problem in teleparallel gravity and explain how the variation with respect to the spin connection should be performed. (orig.)
Renormalization and resolution of singularities
Bergbauer, Christoph; Brunetti, Romeo; Kreimer, Dirk
2009-01-01
Since the seminal work of Epstein and Glaser it is well established that perturbative renormalization of ultraviolet divergences in position space amounts to extension of distributions onto diagonals. For a general Feynman graph the relevant diagonals form a nontrivial arrangement of linear subspaces. One may therefore ask if renormalization becomes simpler if one resolves this arrangement to a normal crossing divisor. In this paper we study the extension problem of distributions onto the won...
Spinfoam cosmology with the proper vertex amplitude
Vilensky, Ilya
2016-01-01
The proper vertex amplitude is derived from the EPRL vertex by restricting to a single gravitational sector in order to achieve the correct semi-classical behaviour. We apply the proper vertex to calculate a cosmological transition amplitude that can be viewed as the Hartle-Hawking wavefunction. To perform this calculation we deduce the integral form of the proper vertex and use extended stationary phase methods to estimate the large-volume limit. We show that the resulting amplitude satisfies an operator constraint whose classical analogue is the Hamiltonian constraint of the Friedmann-Robertson-Walker cosmology. We find that the constraint dynamically selects the relevant family of coherent states and demonstrate a similar dynamic selection in standard quantum mechanics.
Vertex-antimagic Labelings of Regular Graphs
Institute of Scientific and Technical Information of China (English)
Ali AHMAD; Kashif ALI; Martin BA(C)A; Petr KOV(A)(R); Andrea SEMANI(C)OV(A)-FE(N)OV(C)(I)KOV(A)
2012-01-01
Let G =(V,E) be a finite,simple and undirected graph with p vertices and q edges.An (a,d)-vertex-antimagic total labeling of G is a bijection f from V(G).∪E(G) onto the set of consecutive integers 1,2,...,p + q,such that the vertex-weights form an arithmetic progression with the initial term a and difference d,where the vertex-weight of x is the sum of the value f(x) assigned to the vertex x together with all values f(xy) assigned to edges xy incident to x.Such labeling is called super if the smallest possible labels appear on the vertices.In this paper,we study the properties of such labelings and examine their existence for 2r-regular graphs when the difference d is 0,1,...,r + 1.
The Perfect Quark-Gluon Vertex Function
Orginos, K; Brower, Richard C; Chandrasekharan, S; Wiese, U J
1998-01-01
We evaluate a perfect quark-gluon vertex function for QCD in coordinate space and truncate it to a short range. We present preliminary results for the charmonium spectrum using this quasi-perfect action.
Vertex occlusal radiography in localizing unerupted mesiodentes
Directory of Open Access Journals (Sweden)
P Chalakkal
2011-01-01
Full Text Available The aim was to compare the vertex occlusal projection with the anterior maxillary occlusal projection in localizing the position of mesiodentes. Mesiodentes were observed in an 8-year-old boy with an anterior maxillary occlusal radiograph. A vertex occlusal radiograph was taken to compare it with the former in terms of mesiodentes localization with respect to the maxillary central incisors. The vertex occlusal radiograph provided greater details of the position and proximity of mesiodentes with respect to the long axis of maxillary central incisors in comparison to the anterior maxillary occlusal radiograph. Vertex occlusal radiography is an important diagnostic tool in diagnosing the presence, position, and proximity of mesiodentes with respect to the long axis of normally aligned maxillary central incisors. However, it is not recommended for routine use in a patient as its radiation dose is higher than conventional intraoral radiographic methods.
Recursively arbitrarily vertex-decomposable graphs
Directory of Open Access Journals (Sweden)
Olivier Baudon
2012-01-01
Full Text Available A graph \\(G = (V;E\\ is arbitrarily vertex decomposable if for any sequence \\(\\tau\\ of positive integers adding up to \\(|V|\\, there is a sequence of vertex-disjoint subsets of \\(V\\ whose orders are given by \\(\\tau\\, and which induce connected graphs. The main aim of this paper is to study the recursive version of this problem. We present a solution for trees, suns, and partially for a class of 2-connected graphs called balloons.
Track and Vertex Reconstruction in CMS
Adam, W
2006-01-01
The CMS experiment relies on a Silicon pixel and micro-strip tracker for the reconstruction of tracks and vertices of charged particles in the harsh environment of proton and heavy-ion collisions at the LHC at CERN. An outline of the basic track and vertex reconstruction algorithms used in CMS is given and their performance is described. Results of more advanced algorithms like the Gaussian Sum Filter for electron reconstruction and robust vertex fitters are shown.
The analytic renormalization group
Directory of Open Access Journals (Sweden)
Frank Ferrari
2016-08-01
Full Text Available Finite temperature Euclidean two-point functions in quantum mechanics or quantum field theory are characterized by a discrete set of Fourier coefficients Gk, k∈Z, associated with the Matsubara frequencies νk=2πk/β. We show that analyticity implies that the coefficients Gk must satisfy an infinite number of model-independent linear equations that we write down explicitly. In particular, we construct “Analytic Renormalization Group” linear maps Aμ which, for any choice of cut-off μ, allow to express the low energy Fourier coefficients for |νk|<μ (with the possible exception of the zero mode G0, together with the real-time correlators and spectral functions, in terms of the high energy Fourier coefficients for |νk|≥μ. Operating a simple numerical algorithm, we show that the exact universal linear constraints on Gk can be used to systematically improve any random approximate data set obtained, for example, from Monte-Carlo simulations. Our results are illustrated on several explicit examples.
The analytic renormalization group
Ferrari, Frank
2016-08-01
Finite temperature Euclidean two-point functions in quantum mechanics or quantum field theory are characterized by a discrete set of Fourier coefficients Gk, k ∈ Z, associated with the Matsubara frequencies νk = 2 πk / β. We show that analyticity implies that the coefficients Gk must satisfy an infinite number of model-independent linear equations that we write down explicitly. In particular, we construct "Analytic Renormalization Group" linear maps Aμ which, for any choice of cut-off μ, allow to express the low energy Fourier coefficients for |νk | < μ (with the possible exception of the zero mode G0), together with the real-time correlators and spectral functions, in terms of the high energy Fourier coefficients for |νk | ≥ μ. Operating a simple numerical algorithm, we show that the exact universal linear constraints on Gk can be used to systematically improve any random approximate data set obtained, for example, from Monte-Carlo simulations. Our results are illustrated on several explicit examples.
Vertex stability and topological transitions in vertex models of foams and epithelia
Spencer, Meryl A; Lubensky, David K
2016-01-01
In computer simulations of dry foams and of epithelial tissues, vertex models are often used to describe the shape and motion of individual cells. Although these models have been widely adopted, relatively little is known about their basic theoretical properties. For example, while fourfold vertices in real foams are always unstable, it remains unclear whether a simplified vertex model description has the same behavior. Here, we study vertex stability and the dynamics of T1 topological transitions in vertex models. We show that, when all edges have the same tension, stationary fourfold vertices in these models do indeed always break up. In contrast, when tensions are allowed to depend on edge orientation, fourfold vertices can become stable, as is observed in some biological systems. More generally, our formulation of vertex stability leads to an improved treatment of T1 transitions in simulations and paves the way for studies of more biologically realistic models that couple topological transitions to the dy...
Renormalization Group Flows of Hamiltonians Using Tensor Networks
Bal, M.; Mariën, M.; Haegeman, J.; Verstraete, F.
2017-06-01
A renormalization group flow of Hamiltonians for two-dimensional classical partition functions is constructed using tensor networks. Similar to tensor network renormalization [G. Evenbly and G. Vidal, Phys. Rev. Lett. 115, 180405 (2015), 10.1103/PhysRevLett.115.180405; S. Yang, Z.-C. Gu, and X.-G. Wen, Phys. Rev. Lett. 118, 110504 (2017), 10.1103/PhysRevLett.118.110504], we obtain approximate fixed point tensor networks at criticality. Our formalism, however, preserves positivity of the tensors at every step and hence yields an interpretation in terms of Hamiltonian flows. We emphasize that the key difference between tensor network approaches and Kadanoff's spin blocking method can be understood in terms of a change of the local basis at every decimation step, a property which is crucial to overcome the area law of mutual information. We derive algebraic relations for fixed point tensors, calculate critical exponents, and benchmark our method on the Ising model and the six-vertex model.
Renormalization Group Flows of Hamiltonians Using Tensor Networks.
Bal, M; Mariën, M; Haegeman, J; Verstraete, F
2017-06-23
A renormalization group flow of Hamiltonians for two-dimensional classical partition functions is constructed using tensor networks. Similar to tensor network renormalization [G. Evenbly and G. Vidal, Phys. Rev. Lett. 115, 180405 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.180405; S. Yang, Z.-C. Gu, and X.-G. Wen, Phys. Rev. Lett. 118, 110504 (2017)PRLTAO0031-900710.1103/PhysRevLett.118.110504], we obtain approximate fixed point tensor networks at criticality. Our formalism, however, preserves positivity of the tensors at every step and hence yields an interpretation in terms of Hamiltonian flows. We emphasize that the key difference between tensor network approaches and Kadanoff's spin blocking method can be understood in terms of a change of the local basis at every decimation step, a property which is crucial to overcome the area law of mutual information. We derive algebraic relations for fixed point tensors, calculate critical exponents, and benchmark our method on the Ising model and the six-vertex model.
Local renormalization method for random systems
Gittsovich O.; Hubener R.; Rico E.; Briegel H.J.
2010-01-01
In this paper, we introduce a real-space renormalization transformation for random spin systems on 2D lattices. The general method is formulated for random systems and results from merging two well known real space renormalization techniques, namely the strong disorder renormalization technique (SDRT) and the contractor renormalization (CORE). We analyze the performance of the method on the 2D random transverse field Ising model (RTFIM).
Trace Identities for the Topological Vertex
Bryan, Jim; Young, Benjamin
2016-01-01
The topological vertex is a universal series which can be regarded as an object in combinatorics, representation theory, geometry, or physics. It encodes the combinatorics of 3D partitions, the action of vertex operators on Fock space, the Donaldson-Thomas theory of toric Calabi-Yau threefolds, or the open string partition function of $\\mathbb{C}^3$. We prove several identities in which a sum over terms involving the topological vertex is expressed as a closed formula, often a product of simple terms, closely related to Fourier expansions of Jacobi forms. We use purely combinatorial and representation theoretic methods to prove our formulas, but we discuss applications to the Donaldson-Thomas invariants of elliptically fibered Calabi-Yau threefolds at the end of the paper.
Open string amplitudes of closed topological vertex
Takasaki, Kanehisa
2016-01-01
The closed topological vertex is the simplest "off-strip" case of non-compact toric Calabi-Yau threefolds with acyclic web diagrams. By the diagrammatic method of topological vertex, open string amplitudes of topological string theory therein can be obtained by gluing a single topological vertex to an "on-strip" subdiagram of the tree-like web diagram. If non-trivial partitions are assigned to just two parallel external lines of the web diagram, the amplitudes can be calculated with the aid of techniques borrowed from the melting crystal models. These amplitudes are thereby expressed as matrix elements, modified by simple prefactors, of an operator product on the Fock space of 2D charged free fermions. This fermionic expression can be used to derive $q$-difference equations for generating functions of special subsets of the amplitudes. These $q$-difference equations may be interpreted as the defining equation of a quantum mirror curve.
Vertex Operators and Moduli Spaces of Sheaves
Carlsson, Erik
2009-01-01
The Nekrasov partition function in supersymmetric quantum gauge theory is mathematically formulated as an equivariant integral over certain moduli spaces of sheaves on a complex surface. In ``Seiberg-Witten Theory and Random Partitions'', Nekrasov and Okounkov studied these integrals using the representation theory of ``vertex operators'' and the infinite wedge representation. Many of these operators arise naturally from correspondences on the moduli spaces, such as Nakajima's Heisenberg operators, and Grojnowski's vertex operators. In this paper, we build a new vertex operator out of the Chern class of a vector bundle on a pair of moduli spaces. This operator has the advantage that it connects to the partition function by definition. It also incorporates the canonical class of the surface, whereas many other studies assume that the class vanishes. When the moduli space is the Hilbert scheme, we present an explicit expression in the Nakajima operators, and the resulting combinatorial identities. We then apply...
Stevens, Veerle K.; Vleeming, Andry; Bouche, Katie G.; Mahieu, Nele N; Vanderstraeten, Guy G.; Danneels, Lieven A
2006-01-01
Stabilization exercises are intended to optimize function of the muscles that are believed to govern trunk stability. Debate exists whether certain muscles are more important than others in optimally performing these exercises. Thirty healthy volunteers were asked to perform three frequently prescribed stabilization exercises in four-point kneeling. The electromyographic activity of different trunk and hip muscles was evaluated. Average amplitudes obtained during the exercises were normalized...
DEFF Research Database (Denmark)
Bøggild, Peter; Petersen, Dirch Hjorth; Sardan Sukas, Özlem;
2010-01-01
on a cantilever; (ii) scanning micro four point probes allow fast, non- destructive mapping of local electrical properties (sheet resistance and Hall mobility) and hysteresis effects of graphene sheets; (iii) sub 100 nm freestanding devices with wires, heaters, actuators, sensors, resonators and probes were...... defined in a 100 nm thin membrane with focused ion beam milling. By patterning generic membrane templates (Nembranes) the fabrication time of a TEM compatible NEMS device is effectively reduced to less around 20 minutes....
Heat Kernel Renormalization on Manifolds with Boundary
Albert, Benjamin I.
2016-01-01
In the monograph Renormalization and Effective Field Theory, Costello gave an inductive position space renormalization procedure for constructing an effective field theory that is based on heat kernel regularization of the propagator. In this paper, we extend Costello's renormalization procedure to a class of manifolds with boundary. In addition, we reorganize the presentation of the preexisting material, filling in details and strengthening the results.
Renormalization of QED with planar binary trees
Brouder, Christian; Frabetti, Alessandra
2000-01-01
The renormalized photon and electron propagators are expanded over planar binary trees. Explicit recurrence solutions are given for the terms of these expansions. In the case of massless Quantum Electrodynamics (QED), the relation between renormalized and bare expansions is given in terms of a Hopf algebra structure. For massive quenched QED, the relation between renormalized and bare expansions is given explicitly.
Shiba, Hayato; Kawasaki, Takeshi; Onuki, Akira
2012-10-01
We investigate the dynamic heterogeneities of glassy particle systems in the theoretical schemes of bond breakage and four-point correlation functions. In the bond-breakage scheme, we introduce the structure factor Sb(q,t) and the susceptibility χb(t) to detect the spatial correlations of configuration changes. Here χb(t) attains a maximum at t=tbmax as a function of time t, where the fraction of the particles with broken bonds φb(t) is about 1/2. In the four-point scheme, treating the structure factor S4(q,t) and the susceptibility χ4(t), we detect superpositions of the heterogeneity of bond breakage and that of thermal low-frequency vibration modes. While the former grows slowly, the latter emerges quickly to exhibit complex space-time behavior. In two dimensions, the vibration modes extending over the system yield significant contributions to the four-point correlations, which depend on the system size logarithmically. A maximum of χ4(t) is attained at t=t4max, where these two contributions become of the same order. As a result, t4max is considerably shorter than tbmax.
Primary Vertex Reconstruction at the ATLAS Experiment
Grimm, Kathryn; The ATLAS collaboration
2017-01-01
These proceedings present the method and performance of primary vertex reconstruction at the ATLAS experiment during Runs 1 and 2 at the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of $\\sqrt{s} = 8$ TeV, and during 2015-2016 at $\\sqrt{s} = 13$ TeV. Some predictions toward future runs are also presented. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed.
The superB silicon vertex tracker
Energy Technology Data Exchange (ETDEWEB)
Rizzo, G., E-mail: giuliana.rizzo@pi.infn.i [INFN-Pisa and Universita di Pisa (Italy); Avanzini, C.; Batignani, G.; Bettarini, S.; Bosi, F.; Calderini, G.; Ceccanti, M.; Cenci, R.; Cervelli, A.; Crescioli, F.; Dell' Orso, M.; Forti, F.; Giannetti, P.; Giorgi, M.A. [INFN-Pisa and Universita di Pisa (Italy); Lusiani, A. [Scuola Normale Superiore and INFN-Pisa (Italy); Gregucci, S.; Mammini, P.; Marchiori, G.; Massa, M.; Morsani, F. [INFN-Pisa and Universita di Pisa (Italy)
2010-05-21
The SuperB asymmetric e{sup +}-e{sup -} collider has been designed to deliver a luminosity greater than 10{sup 36}cm{sup -2}s{sup -1} with moderate beam currents. Comparing to current B-Factories, the reduced center of mass boost of the SuperB machine requires improved vertex resolution to allow precision measurements sensitive to New Physics. We present the conceptual design of the silicon vertex tracker (SVT) for the SuperB detector with the present status of the R and D on the different options under study for its innermost Layer0.
Vertexing and Tracking Software at LHCb
Bowen, Espen Eie
2015-01-01
The LHCb experiment is a dedicated heavy flavour experiment at the LHC. Its primary goal is to search for indirect evidence of New Physics in CP violation and rare decays of beauty and charm hadrons. The detector includes a high granularity silicon-strip vertex detector, a silicon-strip detector upstream of the magnet and three stations of silicon-strip detectors and straw drift tubes downstream of the magnet. The software used to perform the track reconstruction and primary vertex reconstruction is described in detail along with a discussion of its performance.
On deformation theory of quantum vertex algebras
Grosse, H; Grosse, Harald; Schlesinger, Karl-Georg
2005-01-01
We study an algebraic deformation problem which captures the data of the general deformation problem for a quantum vertex algebra. We derive a system of coupled equations which is the counterpart of the Maurer-Cartan equation on the usual Hochschild complex of an assocative algebra. We show that this system of equations results from an action principle. This might be the starting point for a perturbative treatment of the deformation problem of quantum vertex algebras. Our action generalizes the action of the Kodaira-Spencer theory of gravity and might therefore also be of relevance for applications in string theory.
Vertex Reconstruction for AEGIS’ FACT Detector
Themistokleous, Neofytos
2017-01-01
My project dealt with the development of a vertex reconstruction technique to discriminate antihydrogen from background signals in the AEGIS apparatus. It involved the creation of a Toy Monte-Carlo to simulate particle annihilation events, and a vertex reconstruction utility based on the Bayesian theory of probability. The ﬁrst results based on 107 generated events with single track in the detector are encouraging. For such events, the algorithm can reconstruct the z-coordinate accurately , while for the r-coordinate the result is less accurate.
On spectral theory of quantum vertex operators
Etingof, P
1994-01-01
In this note we prove the Davies-Foda-Jimbo-Miwa-Nakayashiki conjecture on the asymptotics of the composition of n quantum vertex operators for the quantum affine algebra U_q(\\hat sl_2), as n goes to infinity. For this purpose we define and study the leading eigenvalue and eigenvector of the product of two components of the quantum vertex operator. This eigenvector and the corresponding eigenvalue were recently computed by M.Jimbo. The results of his computation are given in Section 4.
Vertex operators in solvable lattice models
Foda, O E; Miwa, T; Miki, K; Nakayashiki, A; Foda, Omar; Jimbo, Michio; Miwa, Tetsuji; Miki, Kei; Nakayashiki, Atsushi
1994-01-01
We formulate the basic properties of q-vertex operators in the context of the Andrews-Baxter-Forrester (ABF) series, as an example of face-interaction models, derive the q-difference equations satisfied by their correlation functions, and establish their connection with representation theory. We also discuss the q-difference equations of the Kashiwara-Miwa (KM) series, as an example of edge-interaction models. Next, the Ising model--the simplest special case of both ABF and KM series--is studied in more detail using the Jordan-Wigner fermions. In particular, all matrix elements of vertex operators are calculated.
Vertex Detector Performance for CLICdet, FCCee & FCChh.
Rasmussen, Peter Winkel
2017-01-01
The performance of the vertex detectors planned for CLICdet, FCCee & FCChh was tested in this project. This was done my studying the figure of merit for a vertex detector which is the transverse impact parameter resolution $\\sigma(d_0)$. This was carried out by simulating single $\\mu^-$ at different energies, polar angles, $\\theta$ with a uniform distribution in the azimuthal angle $\\phi$. The events were reconstructed and the distribution $\\Delta(d_0) = d_{0,reco}-d_{0,true}$ was fitted with a Gaussian function where the width of the function resulted in $\\sigma(d_0)$. The effect of material budget and fit function on this was also tested.
Dynamical gap generation in graphene with frequency-dependent renormalization effects
Carrington, M. E.; Fischer, C. S.; von Smekal, L.; Thoma, M. H.
2016-09-01
We study the frequency dependencies in the renormalization of the fermion Green's function for the π -band electrons in graphene and their influence on the dynamical gap generation at sufficiently strong interaction. Adopting the effective QED-like description for the low-energy excitations within the Dirac-cone region, we self-consistently solve the fermion Dyson-Schwinger equation in various approximations for the photon propagator and the vertex function with special emphasis on frequency-dependent Lindhard screening and retardation effects.
Complex-mass shell renormalization of the higher-derivative electrodynamics
Turcati, Rodrigo; Neves, Mario Junior
2016-08-01
We consider a higher-derivative extension of QED modified by the addition of a gauge-invariant dimension-6 kinetic operator in the U(1) gauge sector. The Feynman diagrams at one-loop level are then computed. The modification in the spin-1 sector leads the electron self-energy and vertex corrections diagrams finite in the ultraviolet regime. Indeed, no regularization prescription is used to calculate these diagrams because the modified propagator always occurs coupled to conserved currents. Moreover, besides the usual massless pole in the spin-1 sector, there is the emergence of a massive one, which becomes complex when computing the radiative corrections at one-loop order. This imaginary part defines the finite decay width of the massive mode. To check consistency, we also derive the decay length using the electron-positron elastic scattering and show that both results are equivalent. Because the presence of this unstable mode, the standard renormalization procedures cannot be used and is necessary adopt an appropriate framework to perform the perturbative renormalization. For this purpose, we apply the complex-mass shell scheme (CMS) to renormalize the aforementioned model. As an application of the formalism developed, we estimate a quantum bound on the massive parameter using the measurement of the electron anomalous magnetic moment and compute the Uehling potential. At the end, the renormalization group is analyzed.
Complex-mass shell renormalization of the higher-derivative electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Turcati, Rodrigo [SISSA, Trieste (Italy); INFN, Sezione di Trieste, Trieste (Italy); Universidade Federal do Espirito Santo, Departamento de Fisica e Quimica, Vitoria, ES (Brazil); Laboratorio de Fisica Experimental (LAFEX), Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro (Brazil); Neves, Mario Junior [Universidade Federal Rural do Rio de Janeiro, Departamento de Fisica, Rio de Janeiro (Brazil)
2016-08-15
We consider a higher-derivative extension of QED modified by the addition of a gauge-invariant dimension-6 kinetic operator in the U(1) gauge sector. The Feynman diagrams at one-loop level are then computed. The modification in the spin-1 sector leads the electron self-energy and vertex corrections diagrams finite in the ultraviolet regime. Indeed, no regularization prescription is used to calculate these diagrams because the modified propagator always occurs coupled to conserved currents. Moreover, besides the usual massless pole in the spin-1 sector, there is the emergence of a massive one, which becomes complex when computing the radiative corrections at one-loop order. This imaginary part defines the finite decay width of the massive mode. To check consistency, we also derive the decay length using the electron-positron elastic scattering and show that both results are equivalent. Because the presence of this unstable mode, the standard renormalization procedures cannot be used and is necessary adopt an appropriate framework to perform the perturbative renormalization. For this purpose, we apply the complex-mass shell scheme (CMS) to renormalize the aforementioned model. As an application of the formalism developed, we estimate a quantum bound on the massive parameter using the measurement of the electron anomalous magnetic moment and compute the Uehling potential. At the end, the renormalization group is analyzed. (orig.)
A Cubic Kernel for Feedback Vertex Set
Bodlaender, H.L.
2006-01-01
The FEEDBACK VERTEX SET problem on unweighted, undirected graphs is considered. Improving upon a result by Burrage et al. [7], we show that this problem has a kernel with O(κ3) vertices, i.e., there is a polynomial time algorithm, that given a graph G and an integer κ, finds a graph G' and integer
Vertex Algebra Sheaf Structure on Torus
Institute of Scientific and Technical Information of China (English)
SUN Yuan-yuan
2016-01-01
In this paper, we first give a 1-1 corresponds between torus C/Λand cubic curve C in P2C. As complex manifold, they are isomorphic, therefore we can treat C/Λas a variety and construction a vertex algebra sheaf on it.
Redford, S
2014-01-01
In order to achieve its primary objectives of heavy-flavour tagging and tau lepton identification, the CLIC vertex detector must precisely reconstruct displaced vertices. This re- quires accurate determination of the impact parameter and charge of tracks originating from the secondary vertex. Excellent spatial resolution must therefore be provided down to low polar angles, whilst maintaining low occupancy, low mass and low power dissipation. These requirements chal- lenge current technological limits, and demand a broad programme of R&D. A detector concept is currently under development, comprising a hybrid pixel detector of small-pitch readout ASICs implemented in 65nm CMOS technology (CLICpix) combined with ultra-thin sensors. The read- out chips are low-power, and power-pulsing is used to reduce further their power dissipation. This enables a forced gas cooling system in the vertex detector region. In this paper, the CLIC vertex detector requirements are reviewed and the current status of R&D on se...
Primary Vertex Reconstruction at the ATLAS Experiment
Grimm, Kathryn; The ATLAS collaboration
2016-01-01
Efficient and precise reconstruction of the primary vertex in an LHC collision is essential in both the reconstruction of the full kinematic properties of a hard-scatter event and of soft interactions as a measure of the amount of pile-up. The reconstruction of primary vertices in the busy, high pile-up environment of Run-2 of the LHC is a challenging task. New methods have been developed by the ATLAS experiment to reconstruct vertices in such environments. Advances in vertex seeding include methods taken from medical imaging, which allow for reconstruction of multiple vertices with small spatial separation. The adoption of this new seeding algorithm within the ATLAS adaptive vertex finding and fitting procedure will be discussed, and the first results of the new techniques from Run-2 data will be presented. Additionally, data-driven methods to evaluate vertex resolution will be presented with special focus on correct methods to evaluate the effect of the beam spot constraint; results from these methods in Ru...
Energy Technology Data Exchange (ETDEWEB)
Battaglia, Marco; Bussat, Jean-Marie; Contarato, Devis; Denes,Peter; Glesener, Lindsay; Greiner, Leo; Hooberman, Benjamin; Shuman,Derek; Tompkins, Lauren; Vu, Chinh; Bisello, Dario; Giubilato, Piero; Pantano, Devis; Costa, Marco; La Rosa, Alessandro; Bolla, Gino; Bortoletto, Daniela; Children, Isaac
2007-10-01
This document summarizes past achievements, current activities and future goals of the R&D program aimed at the design, prototyping and characterization of a full detector module, equipped with monolithic pixel sensors, matching the requirements for the Vertex Tracker at the ILC. We provide a plan of activities to obtain a demonstrator multi-layered vertex tracker equipped with sensors matching the ILC requirements and realistic lightweight ladders in FY11, under the assumption that ILC detector proto-collaborations will be choosing technologies and designs for the Vertex Tracker by that time. The R&D program discussed here started at LBNL in 2004, supported by a Laboratory Directed R&D (LDRD) grant and by funding allocated from the core budget of the LBNL Physics Division and from the Department of Physics at UC Berkeley. Subsequently additional funding has been awarded under the NSF-DOE LCRD program and also personnel have become available through collaborative research with other groups. The aim of the R&D program carried out by our collaboration is to provide a well-integrated, inclusive research effort starting from physics requirements for the ILC Vertex Tracker and addressing Si sensor design and characterization, engineered ladder design, module system issues, tracking and vertex performances and beam test validation. The broad scope of this program is made possible by important synergies with existing know-how and concurrent programs both at LBNL and at the other collaborating institutions. In particular, significant overlaps with LHC detector design, SLHC R&D as well as prototyping for the STAR upgrade have been exploited to optimize the cost per deliverable of our program. This activity is carried out as a collaborative effort together with Accelerator and Fusion Research, the Engineering and the Nuclear Science Divisions at LBNL, INFN and the Department of Physics in Padova, Italy, INFN and the Department of Physics in Torino, Italy and the Department
DEFF Research Database (Denmark)
Eichhorn, V; Fatikow, S; Sardan Sukas, Özlem
2010-01-01
In this paper, a novel nanorobotic strategy for non-destructive and direct electrical characterization of as-grown bundles of single-walled carbon nanotubes (SWCNTs) is presented. For this purpose, test patterns of SWCNT bundles having different diameters are grown on a silicon substrate...... by chemical vapor deposition. A new design of microstructured four-point-probes is proposed and fabricated allowing for direct contacting of vertically aligned bundles of SWCNTs. A nanorobotic setup is upgraded into a dual endeffector system to achieve good electrical contact between four...
Four point function of R-currents in N=4 SYM in the Regge limit at weak coupling
Energy Technology Data Exchange (ETDEWEB)
Bartels, J.; Mischler, A.M.; Salvadore, M. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik
2008-04-15
We compute, in N = 4 super Yang-Mills, the four point correlation function of R-currents in the Regge limit in the leading logarithmic approximation at weak coupling. Such a correlator is the closest analog to photon-photon scattering within QCD, and there is a well defined procedure to perform the analogous computation at strong coupling via AdS/CFT. The main result of this paper is, on the gauge theory side, the proof of Regge factorization and the explicit computation of the R-current impact factors. (orig.)
DEFF Research Database (Denmark)
Shiraki, I.; Nagao, T.; Hasegawa, S.;
2000-01-01
For in-situ measurements of surface conductivity in ultrahigh vacuum (UHV), we have installed micro-four-point probes (probe spacings down to 4 mum) in a UHV scanning electron microscope (SEM) combined with scanning reflection-high-energy electron diffraction (RHEED). With the aid of piezoactuators...... for precise positioning of the probes, local conductivity of selected surface domains of well-defined superstructures could be measured during SEM and RHEED observations. It was found that the surface sensitivity of the conductivity measurements was enhanced by reducing the probe spacing, enabling...
Polyzois, Gregory L; Lagouvardos, Panagiotis E; Frangou, Maria J
2012-06-01
The aim of this study was to (1) investigate the flexural strengths of three denture resins i.e. heat, photopolymerised and microwaved and how it was affected by relining with auto- and visible light-polymerised hard reliners, (2) investigate the bond strengths between denture resins and hard reliners and (3) interpret the results of both tests by utilising Weibull analysis. Specimens (65 × 10 × 2.5 mm) from denture resins, relined and bonded combinations were tested using a four-point bending test in a universal testing machine and a crosshead speed of 5 mm/min. Ten specimens for each bulk resin and denture resin-reliner combination for a total of 150 were tested. Statistical analysis indicated significant differences between bulk materials (p < 0.001) and between reliners (p < 0.001) for flexural and bond strength tests. was concluded that (1) the four-point flexural strength was different between the denture base materials, (2) flexure strength between bulk and relined or between relined with autopolymerised and photopolymerised bases was different, (3) flexural strength among relined denture bases was different and (4) bond strengths among relined denture bases were different. © 2011 The Gerodontology Society and John Wiley & Sons A/S.
Lotz, Mikkel R.; Boll, Mads; Østerberg, Frederik W.; Hansen, Ole; Petersen, Dirch H.
2016-10-01
We have studied the behavior of micro four-point probe (M4PP) measurements on two-dimensional (2D) sheets composed of grains of varying size and grain boundary resistivity by Monte Carlo based finite element (FE) modelling. The 2D sheet of the FE model was constructed using Voronoi tessellation to emulate a polycrystalline sheet, and a square sample was cut from the tessellated surface. Four-point resistances and Hall effect signals were calculated for a probe placed in the center of the square sample as a function of grain density n and grain boundary resistivity ρ GB . We find that the dual configuration sheet resistance as well as the resistance measured between opposing edges of the square sample have a simple unique dependency on the dimension-less parameter √{ n } ρ GB G 0 , where G0 is the sheet conductance of a grain. The value of the ratio R A / R B between resistances measured in A- and B-configurations depends on the dimensionality of the current transport (i.e., one- or two-dimensional). At low grain density or low grain boundary resistivity, two-dimensional transport is observed. In contrast, at moderate grain density and high grain resistivity, one-dimensional transport is seen. Ultimately, this affects how measurements on defective systems should be interpreted in order to extract relevant sample parameters. The Hall effect response in all M4PP configurations was only significant for moderate grain densities and fairly large grain boundary resistivity.
Algebraic Lattices in QFT Renormalization
Borinsky, Michael
2016-07-01
The structure of overlapping subdivergences, which appear in the perturbative expansions of quantum field theory, is analyzed using algebraic lattice theory. It is shown that for specific QFTs the sets of subdivergences of Feynman diagrams form algebraic lattices. This class of QFTs includes the standard model. In kinematic renormalization schemes, in which tadpole diagrams vanish, these lattices are semimodular. This implies that the Hopf algebra of Feynman diagrams is graded by the coradical degree or equivalently that every maximal forest has the same length in the scope of BPHZ renormalization. As an application of this framework, a formula for the counter terms in zero-dimensional QFT is given together with some examples of the enumeration of primitive or skeleton diagrams.
Holographic Renormalization in Dense Medium
Directory of Open Access Journals (Sweden)
Chanyong Park
2014-01-01
describes a dense medium at finite temperature, is investigated in this paper. In a dense medium, two different thermodynamic descriptions are possible due to an additional conserved charge. These two different thermodynamic ensembles are classified by the asymptotic boundary condition of the bulk gauge field. It is also shown that in the holographic renormalization regularity of all bulk fields can reproduce consistent thermodynamic quantities and that the Bekenstein-Hawking entropy is nothing but the renormalized thermal entropy of the dual field theory. Furthermore, we find that the Reissner-Nordström AdS black brane is dual to a theory with conformal matter as expected, whereas a charged black brane with a nontrivial dilaton profile is mapped to a theory with nonconformal matter although its leading asymptotic geometry still remains as AdS space.
Vibrational Density Matrix Renormalization Group.
Baiardi, Alberto; Stein, Christopher J; Barone, Vincenzo; Reiher, Markus
2017-08-08
Variational approaches for the calculation of vibrational wave functions and energies are a natural route to obtain highly accurate results with controllable errors. Here, we demonstrate how the density matrix renormalization group (DMRG) can be exploited to optimize vibrational wave functions (vDMRG) expressed as matrix product states. We study the convergence of these calculations with respect to the size of the local basis of each mode, the number of renormalized block states, and the number of DMRG sweeps required. We demonstrate the high accuracy achieved by vDMRG for small molecules that were intensively studied in the literature. We then proceed to show that the complete fingerprint region of the sarcosyn-glycin dipeptide can be calculated with vDMRG.
CLIQUE IRREDUCIBILITY AND CLIQUE VERTEX IRREDUCIBILITY OF GRAPHS
Vijayakumar, A.; Aparna Lakshmanan S.
2009-01-01
A graphs G is clique irreducible if every clique in G of size at least two, has an edge which does not lie in any other clique of G and is clique reducible if it is not clique irreducible. A graph G is clique vertex irreducible if every clique in G has a vertex which does not lie in any other clique of G and clique vertex reducible if it is not clique vertex irreducible. The clique vertex irreducibility and clique irreducibility of graphs which are non-complete extended p-sums (NEPS) of two g...
Concepts of renormalization in physics.
Alexandre, Jean
2005-01-01
A non technical introduction to the concept of renormalization is given, with an emphasis on the energy scale dependence in the description of a physical system. We first describe the idea of scale dependence in the study of a ferromagnetic phase transition, and then show how similar ideas appear in particle physics. This short review is written for non-particle physicists and/or students aiming at studying particle physics.
Renormalization group flows and anomalies
Komargodski, Zohar
2015-01-01
This chapter reviews various aspects of renormalization group flows and anomalies. The chapter considers specific Euclidean two-dimensional theories. Namely, the theories are invariant under translations and rotations in the two space directions. Here the chapter studies theories where, if possible, certain equations hold in fact also at coincident points. In other words, the chapter looks at theories where there is no local gravitational anomaly.
Renormalization of Dirac's Polarized Vacuum
Lewin, Mathieu
2010-01-01
We review recent results on a mean-field model for relativistic electrons in atoms and molecules, which allows to describe at the same time the self-consistent behavior of the polarized Dirac sea. We quickly derive this model from Quantum Electrodynamics and state the existence of solutions, imposing an ultraviolet cut-off $\\Lambda$. We then discuss the limit $\\Lambda\\to\\infty$ in detail, by resorting to charge renormalization.
Improved Lattice Renormalization Group Techniques
Petropoulos, Gregory; Hasenfratz, Anna; Schaich, David
2013-01-01
We compute the bare step-scaling function $s_b$ for SU(3) lattice gauge theory with $N_f = 12$ massless fundamental fermions, using the non-perturbative Wilson-flow-optimized Monte Carlo Renormalization Group two-lattice matching technique. We use a short Wilson flow to approach the renormalized trajectory before beginning RG blocking steps. By optimizing the length of the Wilson flow, we are able to determine an $s_b$ corresponding to a unique discrete $\\beta$ function, after a few blocking steps. We carry out this study using new ensembles of 12-flavor gauge configurations generated with exactly massless fermions, using volumes up to $32^4$. The results are consistent with the existence of an infrared fixed point (IRFP) for all investigated lattice volumes and number of blocking steps. We also compare different renormalization schemes, each of which indicates an IRFP at a slightly different value of the bare coupling, as expected for an IR-conformal theory.
Optimized Vertex Method and Hybrid Reliability
Smith, Steven A.; Krishnamurthy, T.; Mason, B. H.
2002-01-01
A method of calculating the fuzzy response of a system is presented. This method, called the Optimized Vertex Method (OVM), is based upon the vertex method but requires considerably fewer function evaluations. The method is demonstrated by calculating the response membership function of strain-energy release rate for a bonded joint with a crack. The possibility of failure of the bonded joint was determined over a range of loads. After completing the possibilistic analysis, the possibilistic (fuzzy) membership functions were transformed to probability density functions and the probability of failure of the bonded joint was calculated. This approach is called a possibility-based hybrid reliability assessment. The possibility and probability of failure are presented and compared to a Monte Carlo Simulation (MCS) of the bonded joint.
On the plane-wave cubic vertex
Lucietti, J; Sinha, A K; Lucietti, James; Schäfer-Nameki, Sakura; Sinha, Aninda
2004-01-01
The exact bosonic Neumann matrices of the cubic vertex in plane-wave light-cone string field theory are derived using the contour integration techniques developed in our earlier paper. This simplifies the original derivation of the vertex. In particular, the Neumann matrices are written in terms of \\mu-deformed Gamma-functions, thus casting them into a form that elegantly generalizes the well-known flat-space solution. The asymptotics of the \\mu-deformed Gamma-functions allow one to determine the large-\\mu behaviour of the Neumann matrices including exponential corrections. We provide an explicit expression for the first exponential correction and make a conjecture for the subsequent exponential correction terms.
Hypergraph Partitioning through Vertex Separators on Graphs
Kayaaslan, Enver; Catalyurek, Umit V; Aykanat, Cevdet
2011-01-01
The modeling flexibility provided by hypergraphs has drawn a lot of interest from the combinatorial scientific community, leading to novel models and algorithms, their applications, and development of associated tools. Hypergraphs are now a standard tool in combinatorial scientific computing. The modeling flexibility of hypergraphs however, comes at a cost: algorithms on hypergraphs are inherently more complicated than those on graphs, which sometimes translate to nontrivial increases in processing times. Neither the modeling flexibility of hypergraphs, nor the runtime efficiency of graph algorithms can be overlooked. Therefore, the new research thrust should be how to cleverly trade-off between the two. This work addresses one method for this trade-off by solving the hypergraph partitioning problem by finding vertex separators on graphs. Specifically, we investigate how to solve the hypergraph partitioning problem by seeking a vertex separator on its net intersection graph (NIG), where each net of the hyperg...
Vertex Reconstruction and Performance in ATLAS
Whitmore, Ben William; The ATLAS collaboration
2017-01-01
Efficient and precise reconstruction of the primary vertices in LHC collisions is essential in both the reconstruction of the full kinematic properties of a hard-scatter event and of soft interactions as a measure of the amount of pile-up. The reconstruction of the primary vertices in the busy, high pile up environment of the LHC is a challenging task. The challenges and novel methods developed by the ATLAS experiment to reconstruct vertices in such environments will be presented. The performance of the current vertexing algorithms using Run-2 data will be presented and compared to results from simulation. Additionally, data-driven methods to evaluate vertex resolution, and details of upgrades to the ATLAS inner detector will be presented.
Aoyama, T; Kinoshita, T; Nio, M
2006-01-01
Among 12672 Feynman diagrams contributing to the electron anomalous magnetic moment at the tenth order, 6354 are the diagrams having no lepton loops, i.e., those of quenched type. Because the renormalization structure of these diagrams is very complicated, some automation scheme is inevitable to calculate them. We developed an algorithm to write down FORTRAN programs for numerical evaluation of these diagrams, where the necessary counterterms to subtract out ultraviolet subdivergence are generated according to Zimmermann's forest formula. Thus far we have evaluated crudely integrals of 2232 tenth-order vertex diagrams which require vertex renormalization only. Remaining 4122 diagrams, which have ultraviolet-divergent self-energy subdiagrams and infrared-divergent subdiagrams, are being evaluated by giving small mass lambda to photons to control the infrared problem.
Complex networks renormalization: flows and fixed points.
Radicchi, Filippo; Ramasco, José J; Barrat, Alain; Fortunato, Santo
2008-10-03
Recently, it has been claimed that some complex networks are self-similar under a convenient renormalization procedure. We present a general method to study renormalization flows in graphs. We find that the behavior of some variables under renormalization, such as the maximum number of connections of a node, obeys simple scaling laws, characterized by critical exponents. This is true for any class of graphs, from random to scale-free networks, from lattices to hierarchical graphs. Therefore, renormalization flows for graphs are similar as in the renormalization of spin systems. An analysis of classic renormalization for percolation and the Ising model on the lattice confirms this analogy. Critical exponents and scaling functions can be used to classify graphs in universality classes, and to uncover similarities between graphs that are inaccessible to a standard analysis.
Nonperturbative Aspects of Axial Vector Vertex
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; CHEN Xiang-Song; WANG Fan; CHANG Chao-Hsi; ZHAO En-Guang
2002-01-01
It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.
The ZEUS vertex detector: Design and prototype
Energy Technology Data Exchange (ETDEWEB)
Alvisi, C.; Anzivino, G.; Arzarello, F.; Barbagli, G.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, G.; Bruni, P.; Camerini, U.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Ciralli, F.; Contin, A.; Costa, M.; D' Auria, S.; Del Papa, C.; De Pasquale, S.; Fiori, F.; Forte, A.; Frasconi, F.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Lisowski, B.; Maccarrone, G.; Margotti, A.; Massam, T.; Nania, R.; O' Shea, V.; Palmonari, F.; Pelfer, P.; Pilastrini, R.; Qian, S.; Sartorelli, G.; Schioppa, M.; Susinno, G.; Timellini, R.; Zichichi, A. (European Organization for Nuclear Research, Geneva (Switzerland) Bologna Univ. (Italy). Dipt. di Fisica Cosenza Univ. (Italy). Dipt. di Fisica Florence Univ. (Italy). Dipt. di Fisica Istituto Nazionale di Fisica Nucleare, Bologna (Italy) Istituto Nazionale di Fisica Nucleare, Florence (Italy) Istituto Nazionale di Fisica Nucleare, Frascati (Italy). Lab. Nazionale di Frascati Consiglio Nazionale delle Ricerche, Flore
1991-07-10
A gas vertex detector, operated with dimethylether (DME) at atmospheric pressure, is presently being built for the ZEUS experiment at HERA. Its main design features, together with the performances of a prototype measured at various operating voltages, particle rates and geometrical conditions on a CERN Proton Synchrotron test beam, are presented. A spatial resolution down to 35 {mu}m and an average wire efficiency of 96% have been achieved, for a 3 mm gas gap relative to each sense wire. (orig.).
Bimodules associated to vertex operator superalgebras
Institute of Scientific and Technical Information of China (English)
2008-01-01
Let V be a vertex operator superalgebra and m,n ∈ 21Z+. We construct an An(V ) -Am(V )-bimodule An,m(V ) which characterizes the action of V from the level m subspace to level n subspace of an admissible V -module. We also construct the Verma type admissible V -module from an Am(V )-module by using bimodules
Primary vertex reconstruction with the ATLAS detector
Meloni, Federico; The ATLAS collaboration
2016-01-01
Efficient and precise reconstruction of the primary vertex in a LHC collision is essential for determining the full kinematic properties of a hard-scatter event and of soft interactions as a measure of the amount of pile-up. The reconstruction of primary vertices in the busy, high pile-up environment of Run-2 of the LHC is a challenging task. The algorithms developed by the ATLAS experiments to reconstruct multiple vertices with small spatial separation are presented.
Silicon technologies for the CLIC vertex detector
Spannagel, S.
2017-06-01
CLIC is a proposed linear e+e- collider designed to provide particle collisions at center-of-mass energies of up to 3 TeV. Precise measurements of the properties of the top quark and the Higgs boson, as well as searches for Beyond the Standard Model physics require a highly performant CLIC detector. In particular the vertex detector must provide a single point resolution of only a few micrometers while not exceeding the envisaged material budget of around 0.2% X0 per layer. Beam-beam interactions and beamstrahlung processes impose an additional requirement on the timestamping capabilities of the vertex detector of about 10 ns. These goals can only be met by using novel techniques in the sensor and ASIC design as well as in the detector construction. The R&D program for the CLIC vertex detector explores various technologies in order to meet these demands. The feasibility of planar sensors with a thickness of 50-150 μm, including different active edge designs, are evaluated using Timepix3 ASICs. First prototypes of the CLICpix readout ASIC, implemented in 65 nm CMOS technology and with a pixel size of 25×25μm 2, have been produced and tested in particle beams. An updated version of the ASIC with a larger pixel matrix and improved precision of the time-over-threshold and time-of-arrival measurements has been submitted. Different hybridization concepts have been developed for the interconnection between the sensor and readout ASIC, ranging from small-pitch bump bonding of planar sensors to capacitive coupling of active HV-CMOS sensors. Detector simulations based on Geant 4 and TCAD are compared with experimental results to assess and optimize the performance of the various designs. This contribution gives an overview of the R&D program undertaken for the CLIC vertex detector and presents performance measurements of the prototype detectors currently under investigation.
Buron, Jonas D; Pizzocchero, Filippo; Jessen, Bjarke S; Booth, Timothy J; Nielsen, Peter F; Hansen, Ole; Hilke, Michael; Whiteway, Eric; Jepsen, Peter U; Bøggild, Peter; Petersen, Dirch H
2014-11-12
The electrical performance of graphene synthesized by chemical vapor deposition and transferred to insulating surfaces may be compromised by extended defects, including for instance grain boundaries, cracks, wrinkles, and tears. In this study, we experimentally investigate and compare the nano- and microscale electrical continuity of single layer graphene grown on centimeter-sized single crystal copper with that of previously studied graphene films, grown on commercially available copper foil, after transfer to SiO2 surfaces. The electrical continuity of the graphene films is analyzed using two noninvasive conductance characterization methods: ultrabroadband terahertz time-domain spectroscopy and micro four-point probe, which probe the electrical properties of the graphene film on different length scales, 100 nm and 10 μm, respectively. Ultrabroadband terahertz time-domain spectroscopy allows for measurement of the complex conductance response in the frequency range 1-15 terahertz, covering the entire intraband conductance spectrum, and reveals that the conductance response for the graphene grown on single crystalline copper intimately follows the Drude model for a barrier-free conductor. In contrast, the graphene grown on commercial copper foil shows a distinctly non-Drude conductance spectrum that is better described by the Drude-Smith model, which incorporates the effect of preferential carrier backscattering associated with extended, electronic barriers with a typical separation on the order of 100 nm. Micro four-point probe resistance values measured on graphene grown on single crystalline copper in two different voltage-current configurations show close agreement with the expected distributions for a continuous 2D conductor, in contrast with previous observations on graphene grown on commercial copper foil. The terahertz and micro four-point probe conductance values of the graphene grown on single crystalline copper shows a close to unity correlation, in
B Decay Charm Counting Via Topological Vertexing
Chou, Aaron Sze Ting
2002-01-01
We present a new and unique measurement of the branching fractions of b hadrons to states with 0, 1, and 2 open charm hadrons, using a sample of 350,000 hadronic Z0 decays collected during the SLD/SLC 97–98 run. The analysis takes advantage of the excellent vertexing resolution of the VXD3, a pixel-based CCD vertex detector, which allows the separation of B and cascade D decay vertices. A fit of the vertex count and the decay length distributions to distribution shapes predicted by Monte Carlo simulation allows the extraction of the inclusive branching fractions. We measure: BRB→0D X=3.7±1.1 stat±2.1 syst% BRB→2D X=17.9±1.4 stat±3.3 syst% where B, and D represent mixtures of open b and open c hadrons. The corresponding charm count, Nc = 1.188 ± 0.010 ± 0.040 ± 0.006 is consistent with previous measurement averages but slightly closer to theoretical expectations.
Nonperturbative study of the four gluon vertex
Binosi, D; Papavassiliou, J
2014-01-01
In this paper we study the nonperturbative structure of the SU(3) four-gluon vertex in the Landau gauge, concentrating on contributions quadratic in the metric. We employ an approximation scheme where "one-loop" diagrams are computed using fully dressed gluon and ghost propagators, and tree-level vertices. When a suitable kinematical configuration depending on a single momentum scale $p$ is chosen, only two structures emerge: the tree-level four-gluon vertex, and a tensor orthogonal to it. A detailed numerical analysis reveals that the form factor associated with this latter tensor displays a change of sign (zero-crossing) in the deep infrared, and finally diverges logarithmically. The origin of this characteristic behavior is proven to be entirely due to the masslessness of the ghost propagators forming the corresponding ghost-loop diagram, in close analogy to a similar effect established for the three-gluon vertex. However, in the case at hand, and under the approximations employed, this particular divergen...
B Decay Charm Counting via Topological Vertexing
Energy Technology Data Exchange (ETDEWEB)
Chou, Aaron S
2001-10-15
We present a new and unique measurement of the branching fractions of b hadrons to states with 0, 1, and 2 open charm hadrons, using a sample of 350,000 hadronic Z{sup 0} decays collected during the SLD/SLC 97-98 run. The method takes advantage of the excellent vertexing resolution of the VXD3, a pixel-based CCD vertex detector, which allows the separation of B and cascade D decay vertices. A fit of the vertex count and the decay length distributions to distribution shapes predicted by Monte Carlo simulation allows the extraction of the inclusive branching fractions. We measure: BR(B {yields} (0D)X) = (3.7{+-}1.1(stat) {+-} 2.1(syst))%; and BR(B {yields} (2D)X) = (17.9{+-}1.4(stat) {+-} 3.3(syst))% where B and D represent mixtures of open b and open c hadrons. The corresponding charm count, N{sub c} = 1.188 {+-} 0.010 {+-} 0.040 {+-} 0.006 is consistent with previous measurement averages but slightly closer to theoretical expectations.
Spin wave Feynman diagram vertex computation package
Price, Alexander; Javernick, Philip; Datta, Trinanjan
Spin wave theory is a well-established theoretical technique that can correctly predict the physical behavior of ordered magnetic states. However, computing the effects of an interacting spin wave theory incorporating magnons involve a laborious by hand derivation of Feynman diagram vertices. The process is tedious and time consuming. Hence, to improve productivity and have another means to check the analytical calculations, we have devised a Feynman Diagram Vertex Computation package. In this talk, we will describe our research group's effort to implement a Mathematica based symbolic Feynman diagram vertex computation package that computes spin wave vertices. Utilizing the non-commutative algebra package NCAlgebra as an add-on to Mathematica, symbolic expressions for the Feynman diagram vertices of a Heisenberg quantum antiferromagnet are obtained. Our existing code reproduces the well-known expressions of a nearest neighbor square lattice Heisenberg model. We also discuss the case of a triangular lattice Heisenberg model where non collinear terms contribute to the vertex interactions.
Silicon Technologies for the CLIC Vertex Detector
Spannagel, Simon
2017-01-01
CLIC is a proposed linear e$^+$e$^−$ collider designed to provide particle collisions at center-of-mass energies of up to 3 TeV. Precise measurements of the properties of the top quark and the Higgs boson, as well as searches for Beyond the Standard Model physics require a highly performant CLIC detector. In particular the vertex detector must provide a single point resolution of only a few micrometers while not exceeding the envisaged material budget of around 0.2%$~X_0$ per layer. Beam-beam interactions and beamstrahlung processes impose an additional requirement on the timestamping capabilities of the vertex detector of about 10 ns. These goals can only be met by using novel techniques in the sensor and ASIC design as well as in the detector construction. The R&D program for the CLIC vertex detector explores various technologies in order to meet these demands. The feasibility of planar sensors with a thickness of 50–150$~\\mu$m, including different active edge designs, are evaluated using Timepix3 A...
Constraining differential renormalization in abelian gauge theories
del Águila, F; Tapia, R M; Pérez-Victoria, M
1998-01-01
We present a procedure of differential renormalization at the one loop level which avoids introducing unnecessary renormalization constants and automatically preserves abelian gauge invariance. The amplitudes are expressed in terms of a basis of singular functions. The local terms appearing in the renormalization of these functions are determined by requiring consistency with the propagator equation. Previous results in abelian theories, with and without supersymmetry, are discussed in this context.
Quark Confinement and the Renormalization Group
Ogilvie, Michael C
2010-01-01
Recent approaches to quark confinement are reviewed, with an emphasis on their connection to renormalization group methods. Basic concepts related to confinement are introduced: the string tension, Wilson loops and Polyakov lines, string breaking, string tension scaling laws, center symmetry breaking, and the deconfinement transition at non-zero temperature. Current topics discussed include confinement on $R^3\\times S^1$, the real-space renormalization group, the functional renormalization group, and the Schwinger-Dyson equation approach to confinement.
Electron-phonon vertex in the two-dimensional one-band Hubbard model
Huang, Z. B.; Hanke, W.; Arrigoni, E.; Scalapino, D. J.
2003-12-01
Using quantum Monte Carlo techniques, we study the effects of electronic correlations on the effective electron-phonon (el-ph) coupling in a two-dimensional one-band Hubbard model. We consider a momentum-independent bare ionic el-ph coupling. In the weak- and intermediate-correlation regimes, we find that the on-site Coulomb interaction U acts to effectively suppress the ionic el-ph coupling at all electron and phonon momenta. In this regime, our numerical simulations are in good agreement with the results of perturbation theory to order U2. However, entering the strong-correlation regime, we find that the forward-scattering process stops decreasing and begins to substantially increase as a function of U, leading to an effective el-ph coupling which is peaked in the forward direction. Whereas at weak and intermediate Coulomb interactions, screening is the dominant correlation effect suppressing the el-ph coupling, at larger U values irreducible vertex corrections become more important and give rise to this increase. These vertex corrections depend crucially on the renormalized electronic structure of the strongly correlated system.
Energy Technology Data Exchange (ETDEWEB)
Ge, Jian-Feng; Liu, Zhi-Long; Gao, Chun-Lei; Qian, Dong; Liu, Canhua, E-mail: canhualiu@sjtu.edu.cn, E-mail: jfjia@sjtu.edu.cn; Jia, Jin-Feng, E-mail: canhualiu@sjtu.edu.cn, E-mail: jfjia@sjtu.edu.cn [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)
2015-05-15
Electrons at surface may behave differently from those in bulk of a material. Multi-functional tools are essential in comprehensive studies on a crystal surface. Here, we developed an in situ microscopic four-point probe (4PP) transport measurement system on the basis of a scanning tunneling microscope (STM). In particular, convenient replacement between STM tips and micro-4PPs enables systematic investigations of surface morphology, electronic structure, and electrical transport property of a same sample surface. Performances of the instrument are demonstrated with high-quality STM images, tunneling spectra, and low-noise electrical I-V characteristic curves of a single-layer FeSe film grown on a conductive SrTiO{sub 3} surface.
Energy Technology Data Exchange (ETDEWEB)
Kehagias, A., E-mail: kehagias@central.ntua.gr [Physics Division, National Technical University of Athens, 15780 Zografou Campus, Athens (Greece); Riotto, A. [Department of Theoretical Physics and Center for Astroparticle Physics (CAP), 24 quai E. Ansermet, CH-1211 Geneva 4 (Switzerland)
2013-03-21
We study the multifield inflationary models where the cosmological perturbation is sourced by light scalar fields other than the inflaton. We exploit the operator product expansion and partly the symmetries present during the de Sitter epoch to characterize the non-Gaussian four-point correlator in the squeezed limit. We point out that the contribution to it from the intrinsic non-Gaussianity of the light fields at horizon crossing can be larger than the usually studied contribution arising on superhorizon scales and it comes with a different shape. Our findings indicate that particular attention needs to be taken when studying the effects of the primordial NG on real observables, such as the clustering of dark matter halos.
DEFF Research Database (Denmark)
Lotz, Mikkel Rønne; Boll, Mads; Østerberg, Frederik Westergaard
2016-01-01
We have studied the behavior of micro four-point probe (M4PP) measurements on two-dimensional (2D) sheets composed of grains of varying size and grain boundary resistivity by Monte Carlo based finite element (FE) modelling. The 2D sheet of the FE model was constructed using Voronoi tessellation......-configurations depends on the dimensionality of the current transport (i.e., one- or two-dimensional). At low grain density or low grain boundary resistivity, two-dimensional transport is observed. In contrast, at moderate grain density and high grain resistivity, one-dimensional transport is seen. Ultimately......, this affects how measurements on defective systems should be interpreted in order to extract relevant sample parameters. The Hall effect response in all M4PP configurations was only significant for moderate grain densities and fairly large grain boundary resistivity....
Yu, Chang Ho; Kang, Seung Rok; Jeong, Ho Choon; Kim, Kyung; Kwon, Tae Kyu
2014-01-01
This study was performed to assess the improvement of muscle strength imbalance in the lower limbs using a four point weight bearing reduction system with a two-belt treadmill. Participants, each having differences in muscle function of the left and right legs of over 20%, were divided into two groups of ten. The participants were involved in experiments progressing 40 minutes per day, 3 days per week, during a period of 4 weeks. The maximal peak torque and average power were measured for testing joint torque in the hip, knee and ankle. The results showed the improvement of muscle imbalance as assessed by the maximal muscle strength was the most effective in the hip joint, while the improvement of muscular reaction was the most effective in the knee joint. We suggest that the method of weight bearing reduction could be sufficient to reduce muscle imbalance in the lower limbs.
DEFF Research Database (Denmark)
Kjær, Daniel; Hansen, Ole; Østerberg, Frederik Westergaard;
2015-01-01
Thin-film sheet resistance measurements at high spatial resolution and on small pads are important and can be realized with micrometer-scale four-point probes. As a result of the small scale the measurements are affected by electrode position errors. We have characterized the electrode position...... errors in measurements on Ru thin film using an Au-coated 12-point probe. We show that the standard deviation of the static electrode position error is on the order of 5 nm, which significantly affects the results of single configuration measurements. Position-error-corrected dual......-configuration measurements, however, are shown to eliminate the effect of position errors to a level limited either by electrical measurement noise or dynamic position errors. We show that the probe contact points remain almost static on the surface during the measurements (measured on an atomic scale) with a standard...
Pang, Fei; Liang, Xuejin; Chen, Dongmin
2013-07-01
We present a simple method to fabricate microscopic four-point probe (M4PP) with spacing of 70-100 μm for conductivity measurements in ultrahigh vacuum. The probe includes four gold wires with 30 μm diameter and a 0.5 mm thickness sapphire slice as cantilever. One of the dual scanning tunneling microscope (DSTM) is replaced by M4PP. As a result, in situ transport measurement could be performed by M4PP and investigation of surface morphology by STM. Finally, we measure conductivity of 14 monolayer Bi(111) epitaxial film on n type Si which is 1.6 × 10(-3) Ω(-1)∕[larger open square].
Ge, Jian-Feng; Liu, Zhi-Long; Gao, Chun-Lei; Qian, Dong; Liu, Canhua; Jia, Jin-Feng
2015-05-01
Electrons at surface may behave differently from those in bulk of a material. Multi-functional tools are essential in comprehensive studies on a crystal surface. Here, we developed an in situ microscopic four-point probe (4PP) transport measurement system on the basis of a scanning tunneling microscope (STM). In particular, convenient replacement between STM tips and micro-4PPs enables systematic investigations of surface morphology, electronic structure, and electrical transport property of a same sample surface. Performances of the instrument are demonstrated with high-quality STM images, tunneling spectra, and low-noise electrical I-V characteristic curves of a single-layer FeSe film grown on a conductive SrTiO3 surface.
Renormalization of Extended QCD$_2$
Fukaya, Hidenori
2015-01-01
Extended QCD (XQCD) proposed by Kaplan [1] is an interesting reformulation of QCD with additional bosonic auxiliary fields. While its partition function is kept exactly the same as that of original QCD, XQCD naturally contains properties of low energy hadronic models. We analyze the renormalization group flow of two-dimensional (X)QCD, which is solvable in the limit of large number of colors Nc, to understand what kind of roles the auxiliary degrees of freedom play and how the hadronic picture emerges in the low energy region.
Renormalization Group and Phase Transitions in Spin, Gauge, and QCD Like Theories
Energy Technology Data Exchange (ETDEWEB)
Liu, Yuzhi [Univ. of Iowa, Iowa City, IA (United States)
2013-08-01
In this thesis, we study several different renormalization group (RG) methods, including the conventional Wilson renormalization group, Monte Carlo renormalization group (MCRG), exact renormalization group (ERG, or sometimes called functional RG), and tensor renormalization group (TRG).
Renormalization of dimension 6 gluon operators
Directory of Open Access Journals (Sweden)
HyungJoo Kim
2015-09-01
Full Text Available We identify the independent dimension 6 twist 4 gluon operators and calculate their renormalization in the pure gauge theory. By constructing the renormalization group invariant combinations, we find the scale invariant condensates that can be estimated in nonperturbative calculations and used in QCD sum rules for heavy quark systems in medium.
Improved system identification with Renormalization Group.
Wang, Qing-Guo; Yu, Chao; Zhang, Yong
2014-09-01
This paper proposes an improved system identification method with Renormalization Group. Renormalization Group is applied to a fine data set to obtain a coarse data set. The least squares algorithm is performed on the coarse data set. The theoretical analysis under certain conditions shows that the parameter estimation error could be reduced. The proposed method is illustrated with examples.
Renormalization of Lepton Mixing for Majorana Neutrinos
Broncano, A; Jenkins, E; Jenkins, Elizabeth
2005-01-01
We discuss the one-loop electroweak renormalization of the leptonic mixing matrix in the case of Majorana neutrinos, and establish its relationship with the renormalization group evolution of the dimension five operator responsible for the light Majorana neutrino masses. We compare our results in the effective theory with those in the full seesaw theory.
Renormalization of lepton mixing for Majorana neutrinos
Energy Technology Data Exchange (ETDEWEB)
Broncano, A. [Departamento de Fisica Teorica, C-XI, and IFT, C-XVI, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)]. E-mail: alicia.broncano@uam.es; Gavela, M.B. [Departamento de Fisica Teorica, C-XI, and IFT, C-XVI, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)]. E-mail: gavela@delta.ft.uam.es; Jenkins, Elizabeth [Department of Physics, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States)]. E-mail: ejenkins@ucsd.edu
2005-01-17
We discuss the one-loop electroweak renormalization of the leptonic mixing matrix in the case of Majorana neutrinos, and establish its relationship with the renormalization group evolution of the dimension five operator responsible for the light Majorana neutrino masses. We compare our results in the effective theory with those in the full seesaw theory.
An alternative to exact renormalization equations
Alexandre, Jean
2005-01-01
An alternative point of view to exact renormalization equations is discussed, where quantum fluctuations of a theory are controlled by the bare mass of a particle. The procedure is based on an exact evolution equation for the effective action, and recovers usual renormalization results.
Adu, Stephen Aboagye
Laminated carbon fiber-reinforced polymer composites (CFRPs) possess very high specific strength and stiffness and this has accounted for their wide use in structural applications, most especially in the aerospace industry, where the trade-off between weight and strength is critical. Even though they possess much larger strength ratio as compared to metals like aluminum and lithium, damage in the metals mentioned is rather localized. However, CFRPs generate complex damage zones at stress concentration, with damage progression in the form of matrix cracking, delamination and fiber fracture or fiber/matrix de-bonding. This thesis is aimed at performing; stiffness degradation analysis on composite coupons, containing embedded delamination using the Four-Point Bend Test. The Lamb wave-based approach as a structural health monitoring (SHM) technique is used for damage detection in the composite coupons. Tests were carried-out on unidirectional composite coupons, obtained from panels manufactured with pre-existing defect in the form of embedded delamination in a laminate of stacking sequence [06/904/0 6]T. Composite coupons were obtained from panels, fabricated using vacuum assisted resin transfer molding (VARTM), a liquid composite molding (LCM) process. The discontinuity in the laminate structure due to the de-bonding of the middle plies caused by the insertion of a 0.3 mm thick wax, in-between the middle four (4) ninety degree (90°) plies, is detected using lamb waves generated by surface mounted piezoelectric (PZT) actuators. From the surface mounted piezoelectric sensors, response for both undamaged (coupon with no defect) and damaged (delaminated coupon) is obtained. A numerical study of the embedded crack propagation in the composite coupon under four-point and three-point bending was carried out using FEM. Model validation was then carried out comparing the numerical results with the experimental. Here, surface-to-surface contact property was used to model the
Directory of Open Access Journals (Sweden)
Ghazvini Ferooz M
2014-09-01
Full Text Available Statement of Problem: Resin composites are a common type of tooth coloured restorative materials. These materials are brittle and their major shortcomings are sensitivity to flaws and defects, low tensile strength, and susceptibility to catastrophic failure.The role of home bleaching agents on the fracture toughness of resin composites using four-point bending test is scanty. Objectives: To compare the fracture toughness (KIc of resin composites on a fourpoint bending test and to assess the effect of distilled water and a home bleaching agent on the resistance of the materials to fracture. Materials and Methods: seventy-two bar-shaped specimens were prepared from three materials: Rok (SDI, Estelite (Tokuyama, and Vit-l-escence (Ultradent and divided into three groups. Two groups were assigned as “control” and conditioned in distilled water at 37oC for 24 hours or 21 days, respectively. The specimens in the third group (treatment were stored in distilled water for 21 days and bleached using Polanight (SDI for 2 hours daily. For each material, a total of 24 disc-shaped specimens were prepared and after each time interval loaded in a four-point bending test using a universal testing machine with a crosshead speed of 0.5 mm/m. The maximum load to specimen failure was recorded and the KIc was calculated. Results: Statistical analysis using two-way ANOVA showed a significant relationship between materials and treatment (P<0.05. Tukey’s test showed that after 24 hours of immersion in distilled water, KIc was not significantly different between materials; Rok revealed the highest value followed by Estelite and Vit-l-escence. The bleaching agent significantly decreased the KIc values of Estelite and Rok while it did not affect that of Vita-l-escence. Immersion in distilled water for all resin composites caused a significant decrease in KIc. Conclusion: The fracture toughness of the resin composites was affected by the bleaching agent and 21day
The Belle II Silicon Vertex Detector
Energy Technology Data Exchange (ETDEWEB)
Friedl, M., E-mail: markus.friedl@oeaw.ac.at [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Ackermann, K. [MPI Munich, Föhringer Ring 6, 80805 München (Germany); Aihara, H. [University of Tokyo, Department of Physics, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Aziz, T. [Tata Institute of Fundamental Research, Experimental High Energy Physics Group, Homi Bhabha Road, Mumbai 400 005 (India); Bergauer, T. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Bozek, A. [Institute of Nuclear Physics, Division of Particle Physics and Astrophysics, ul. Radzikowskiego 152, 31 342 Krakow (Poland); Campbell, A. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Dingfelder, J. [University of Bonn, Department of Physics and Astronomy, Nussallee 12, 53115 Bonn (Germany); Drasal, Z. [Charles University, Institute of Particle and Nuclear Physics, Ke Karlovu 3, 121 16 Praha 2 (Czech Republic); Frankenberger, A. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Gadow, K. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Gfall, I. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Haba, J.; Hara, K.; Hara, T. [KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Higuchi, T. [University of Tokyo, Kavli Institute for Physics and Mathematics of the Universe, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Himori, S. [Tohoku University, Department of Physics, Aoba Aramaki Aoba-ku, Sendai 980-8578 (Japan); Irmler, C. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Ishikawa, A. [Tohoku University, Department of Physics, Aoba Aramaki Aoba-ku, Sendai 980-8578 (Japan); Joo, C. [Seoul National University, High Energy Physics Laboratory, 25-107 Shinlim-dong, Kwanak-gu, Seoul 151-742 (Korea, Republic of); and others
2013-12-21
The KEKB machine and the Belle experiment in Tsukuba (Japan) are now undergoing an upgrade, leading to an ultimate luminosity of 8×10{sup 35}cm{sup −2}s{sup −1} in order to measure rare decays in the B system with high statistics. The previous vertex detector cannot cope with this 40-fold increase of luminosity and thus needs to be replaced. Belle II will be equipped with a two-layer Pixel Detector surrounding the beam pipe, and four layers of double-sided silicon strip sensors at higher radii than the old detector. The Silicon Vertex Detector (SVD) will have a total sensitive area of 1.13m{sup 2} and 223,744 channels—twice as many as its predecessor. All silicon sensors will be made from 150 mm wafers in order to maximize their size and thus to reduce the relative contribution of the support structure. The forward part has slanted sensors of trapezoidal shape to improve the measurement precision and to minimize the amount of material as seen by particles from the vertex. Fast-shaping front-end amplifiers will be used in conjunction with an online hit time reconstruction algorithm in order to reduce the occupancy to the level of a few percent at most. A novel “Origami” chip-on-sensor scheme is used to minimize both the distance between strips and amplifier (thus reducing the electronic noise) as well as the overall material budget. This report gives an overview on the status of the Belle II SVD and its components, including sensors, front-end detector ladders, mechanics, cooling and the readout electronics.
Extended technicolor contribution to the Zbb vertex
Hagiwara, K; Hagiwara, Kaoru; Kitazawa, Noriaki
1995-01-01
We show that the flavor-diagonal gauge boson of the extended technicolor theory contributes with opposite sign to the standard model correction for the Zbb vertex. This mechanism can naturally explain the deviation of the LEP result from the standard model prediction for the partial width \\Gamma(Z \\rightarrow b{\\bar b}). A smaller value of the QCD coupling, \\alpha_s(m_Z) \\simeq 0.115, is then preferred by the \\Gamma(Z \\rightarrow \\mbox{hadron}) data, which is consistent with both the recent Lattice-QCD estimate and the Particle Data Group average.
The Mark II Vertex Drift Chamber
Energy Technology Data Exchange (ETDEWEB)
Alexander, J.P.; Baggs, R.; Fujino, D.; Hayes, K.; Hoard, C.; Hower, N.; Hutchinson, D.; Jaros, J.A.; Koetke, D.; Kowalski, L.A.
1989-03-01
We have completed constructing and begun operating the Mark II Drift Chamber Vertex Detector. The chamber, based on a modified jet cell design, achieves 30 {mu}m spatial resolution and <1000 {mu}m track-pair resolution in pressurized CO{sub 2} gas mixtures. Special emphasis has been placed on controlling systematic errors including the use of novel construction techniques which permit accurate wire placement. Chamber performance has been studied with cosmic ray tracks collected with the chamber located both inside and outside the Mark II. Results on spatial resolution, average pulse shape, and some properties of CO{sub 2} mixtures are presented. 10 refs., 12 figs., 1 tab.
On the vertex index of convex bodies
Bezdek, Karoly
2011-01-01
We introduce the vertex index, vein(K), of a given centrally symmetric convex body K, which, in a sense, measures how well K can be inscribed into a convex polytope with small number of vertices. This index is closely connected to the illumination parameter of a body, introduced earlier by the first named author, and, thus, related to the famous conjecture in Convex Geometry about covering of a d-dimensional body by 2^d smaller positively homothetic copies. We provide asymptotically sharp estimates (up to a logarithmic term) of this index in the general case. Also, we provide sharp estimates in dimensions 2 and 3.
Radiation damage in the LHCb Vertex Locator
Affolder, A; Akiba, K.; Alexander, M.; Ali, S.; Artuso, M.; Benton, J.; van Beuzekom, M.; Bjørnstad, P M; Bogdanova, G; Borghi, S.; Bowcock, T. J. V.; Brown, H.; Buytaert, J.; Casse, G.; Collins, P.
2013-01-01
The LHCb Vertex Locator (VELO) is a silicon strip detector designed to reconstruct charged particle trajectories and vertices produced at the LHCb interaction region. During the first two years of data collection, the 84 VELO sensors have been exposed to a range of fluences up to a maximum value of approximately $\\rm{45 \\times 10^{12}\\,1\\,MeV}$ neutron equivalent ($\\rm{1\\,MeV\\,n_{eq}}$). At the operational sensor temperature of approximately $-7\\,^{\\circ}\\rm{C}$, the average rate of sensor cu...
Performance of the LHCb Vertex Locator
Latham, T
2012-01-01
LHCb is a dedicated flavour physics experiment at the Large Hadron Collider (LHC) at CERN. The Vertex Locator (VELO) is an essential part of the LHCb detector, permitting precision measurements of the production and decay vertices of beauty and charm particles. The VELO consists of a series of silicon micro-strip detectors, arranged in two retractable halves. Positioned only 7 mm from the beam during normal operations, it must withstand very high levels of radiation. The performance of the LHCb VELO during the first year of LHC physics running is presented.
Wavelet view on renormalization group
Altaisky, M V
2016-01-01
It is shown that the renormalization group turns to be a symmetry group in a theory initially formulated in a space of scale-dependent functions, i.e, those depending on both the position $x$ and the resolution $a$. Such theory, earlier described in {\\em Phys.Rev.D} 81(2010)125003, 88(2013)025015, is finite by construction. The space of scale-dependent functions $\\{ \\phi_a(x) \\}$ is more relevant to physical reality than the space of square-integrable functions $\\mathrm{L}^2(R^d)$, because, due to the Heisenberg uncertainty principle, what is really measured in any experiment is always defined in a region rather than point. The effective action $\\Gamma_{(A)}$ of our theory turns to be complementary to the exact renormalization group effective action. The role of the regulator is played by the basic wavelet -- an "aperture function" of a measuring device used to produce the snapshot of a field $\\phi$ at the point $x$ with the resolution $a$. The standard RG results for $\\phi^4$ model are reproduced.
Seiler, Christian; Evers, Ferdinand
2016-10-01
A formalism for electronic-structure calculations is presented that is based on the functional renormalization group (FRG). The traditional FRG has been formulated for systems that exhibit a translational symmetry with an associated Fermi surface, which can provide the organization principle for the renormalization group (RG) procedure. We here advance an alternative formulation, where the RG flow is organized in the energy-domain rather than in k space. This has the advantage that it can also be applied to inhomogeneous matter lacking a band structure, such as disordered metals or molecules. The energy-domain FRG (ɛ FRG) presented here accounts for Fermi-liquid corrections to quasiparticle energies and particle-hole excitations. It goes beyond the state of the art G W -BSE , because in ɛ FRG the Bethe-Salpeter equation (BSE) is solved in a self-consistent manner. An efficient implementation of the approach that has been tested against exact diagonalization calculations and calculations based on the density matrix renormalization group is presented. Similar to the conventional FRG, also the ɛ FRG is able to signalize the vicinity of an instability of the Fermi-liquid fixed point via runaway flow of the corresponding interaction vertex. Embarking upon this fact, in an application of ɛ FRG to the spinless disordered Hubbard model we calculate its phase boundary in the plane spanned by the interaction and disorder strength. Finally, an extension of the approach to finite temperatures and spin S =1 /2 is also given.
Directory of Open Access Journals (Sweden)
A. Pedersen
Full Text Available For accurate measurements of electric fields, spherical double probes are electronically controlled to be at a positive potential of approximately 1 V relative to the ambient magnetospheric plasma. The spacecraft will acquire a potential which balances the photoelectrons escaping to the plasma and the electron flux collected from the plasma. The probe-to-plasma potential difference can be measured with a time resolution of a fraction of a second, and provides information on the electron density over a wide range of electron densities from the lobes (~ 0.01 cm^{-3} to the magnetosheath (>10 cm^{-3} and the plasmasphere (>100 cm^{-3}. This technique has been perfected and calibrated against other density measurements on GEOS, ISEE-1, CRRES, GEOTAIL and POLAR. The Cluster spacecraft potential measurements opens the way for new approaches, particularly near boundaries and gradients where four-point measurements will provide information never obtained before. Another interesting point is that onboard data storage of this simple parameter can be done for complete orbits and thereby will provide background information for the shorter full data collection periods on Cluster. Preliminary calibrations against other density measurements on Cluster will be reported.
Key words. Magnetospheric physics (magnetopause, cusp, and boundary layers Space plasma physics (spacecraft sheaths, wakes, charging; instruments and techniques
Energy Technology Data Exchange (ETDEWEB)
Oyunbaatar, Nomin-Erdene; Choi, Young Soo; Lee, Dong-Weon, E-mail: mems@jnu.ac.kr [MEMS and Nanotechnology Laboratory, School of Mechanical Engineering, Chonnam National University, Gwangju 500757 (Korea, Republic of)
2015-12-15
This paper describes a self-adjustable four-point probe (S4PP) system with a square configuration. The S4PP system consists of 3D polymer coil springs for the independent operation of each tungsten (W) probe, microfluidic channels filled with a nontoxic liquid metal, and a LabView-based control system. The 3D coil springs made by PMMA are fabricated with a 3D printer and are positioned in a small container filled with the non-toxic liquid metal. This unique configuration allows independent self-adjustment of the probe heights for precise measurements of the electrical properties of both flexible and large-step-height microsamples. The feasibility of the fabricated S4PP system is evaluated by measuring the specific resistance of Cr and Au thin films deposited on silicon wafers. The system is then employed to evaluate the electrical properties of a Au thin film deposited onto a flexible and easily breakable silicon diaphragm (spring constant: ∼3.6 × 10{sup −5} N/m). The resistance of the Cr thin films (thickness: 450 nm) with step heights of 60 and 90 μm is also successfully characterized. These experimental results indicate that the proposed S4PP system can be applied to common metals and semiconductors as well as flexible and large-step-height samples.
Oyunbaatar, Nomin-Erdene; Choi, Young Soo; Choi, Yong Soo; Lee, Dong-Weon
2015-12-01
This paper describes a self-adjustable four-point probe (S4PP) system with a square configuration. The S4PP system consists of 3D polymer coil springs for the independent operation of each tungsten (W) probe, microfluidic channels filled with a nontoxic liquid metal, and a LabView-based control system. The 3D coil springs made by PMMA are fabricated with a 3D printer and are positioned in a small container filled with the non-toxic liquid metal. This unique configuration allows independent self-adjustment of the probe heights for precise measurements of the electrical properties of both flexible and large-step-height microsamples. The feasibility of the fabricated S4PP system is evaluated by measuring the specific resistance of Cr and Au thin films deposited on silicon wafers. The system is then employed to evaluate the electrical properties of a Au thin film deposited onto a flexible and easily breakable silicon diaphragm (spring constant: ∼3.6 × 10(-5) N/m). The resistance of the Cr thin films (thickness: 450 nm) with step heights of 60 and 90 μm is also successfully characterized. These experimental results indicate that the proposed S4PP system can be applied to common metals and semiconductors as well as flexible and large-step-height samples.
Lee, Seung-Yong; Lee, Mi-Ri; Park, No-Won; Kim, Gil-Sung; Choi, Heon-Jin; Choi, Tae-Youl; Lee, Sang-Kwon
2013-12-13
We report on a systematic study of the thermal transport characteristics of both as-grown zinc oxide and gallium nitride nanowires (NWs) via the four-point-probe 3-ω method in the temperature range 130-300 K. Both as-grown NWs were synthesized by a vapor-liquid-solid growth mechanism, and show clear n-type semiconducting behavior without any defects, which enables both the NWs to be promising candidates for thermoelectric materials. To measure the thermal conductivities of both NWs with lower heat loss and measurement errors, the suspended structures were formed by a combination of an e-beam lithography process and a random dispersion method. The measured thermal conductivities of both NWs are greatly reduced compared to their bulk materials due to the enhanced phonon scattering via the size effect and dopants (impurities). Furthermore, we observed that the Umklapp peaks of both NWs are shifted to a higher temperature than those of their bulk counterparts, indicating that phonon-boundary scattering dominates over other phonon scattering due to the size effect.
Quasi-lisse vertex algebras and modular linear differential equations
Arakawa, Tomoyuki
2016-01-01
We introduce a notion of quasi-lisse vertex algebras, which generalizes admissible affine vertex algebras. We show that the normalized character of an ordinary module over a quasi-lisse vertex operator algebra has a modular invariance property, in the sense that it satisfies a modular linear differential equation. As an application we obtain the explicit character formulas of simple affine vertex algebras associated with the Deligne exceptional series at level $-h^{\\vee}/6-1$, which expresses the homogeneous Schur limit of the superconformal index of 4d SCFTs studied by Beem, Lemos, Liendo, Peelaers, Rastelli and van Rees, as quasi-modular forms.
Markov branching in the vertex splitting model
Stefansson, Sigurdur Orn
2011-01-01
We study a special case of the vertex splitting model which is a recent model of randomly growing trees. For any finite maximum vertex degree $D$, we find a one parameter model, with parameter $\\alpha \\in [0,1]$ which has a so--called Markov branching property. When $D=\\infty$ we find a two parameter model with an additional parameter $\\gamma \\in [0,1]$ which also has this feature. In the case $D = 3$, the model bears resemblance to Ford's $\\alpha$--model of phylogenetic trees and when $D=\\infty$ it is similar to its generalization, the $\\alpha\\gamma$--model. For $\\alpha = 0$, the model reduces to the well known model of preferential attachment. In the case $\\alpha > 0$, we prove convergence of the finite volume probability measures, generated by the growth rules, to a measure on infinite trees which is concentrated on the set of trees with a single spine. We show that the annealed Hausdorff dimension with respect to the infinite volume measure is $1/\\alpha$. When $\\gamma = 0$ the model reduces to a model of ...
The Construction of Spin Foam Vertex Amplitudes
Bianchi, Eugenio
2012-01-01
Spin foam vertex amplitudes are the key ingredient of spin foam models for quantum gravity. They fall into the realm of discretized path integral, and can be seen as generalized lattice gauge theories. They can be seen as an attempt at a 4 dimensional generalization of the Ponzano-Regge model for 3d quantum gravity. We motivate and review the construction of the vertex amplitudes of recent spin foam models, giving two different and complementary perspectives of this construction. The first proceeds by extracting geometric configurations from a topological theory of the BF type, and can be seen to be in the tradition of the work of Barret and Crane and Freidel and Krasnov. The second keeps closer contact to the structure of Loop Quantum Gravity and tries to identify an appropriate set of constraints to define a Lorentz-invariant interaction of its quanta of space. This approach is in the tradition of the work of Smolin, Markopoulous, Engle, Pereira, Rovelli and Livine.
The LHCb level 1 vertex trigger
Koratzinos, M
1999-01-01
Summary form only given. The Level 1 Vertex trigger of LHCb has certain features that make it unique amongst the LHC experiment trigger schemes: The problem it addresses is a reduction factor of 25 for minimum bias events while retaining good efficiency for signal B events. The best way to achieve such reduction factors is to rely on the most striking property of those B events, the long decay time of the B particles. The trigger therefore has to reconstruct the event around the interaction region and tag signal events using topological criteria. An accurate vertex detector is one of the key components of LHCb and a natural choice for providing the data for such a triggering scheme. The algorithm for the reconstruction of the event is complicated and not readily parallelisable in its totality. We are therefore proposing an architecture that resembles a high-level trigger architecture, where the event building function is performed by a switch network and each event is processed by a single processor, part of ...
First Results from the LHCb Vertex Locator
Borghi, S
2010-01-01
LHCb is a dedicated experiment to study new physics in the decays of beauty and charm hadrons at the Large Hadron Collider (LHC) at CERN. The beauty and charm hadrons are identified through their flight distance in the Vertex Locator (VELO), and hence the detector is critical for both the trigger and offline physics analyses. The VELO is the silicon detector surrounding the interaction point, and is the closest LHC vertex detector to the interaction point, located only 7 mm from the LHC beam during normal operation. The detector will operate in an extreme and highly non-uniform radiation environment. The VELO consists of two retractable detector halves with 21 silicon micro-strip tracking modules each. A module is composed of two n+-on-n 300 micron thick half disc sensors with R-measuring and Phi-measuring micro-strip geometry, mounted on a carbon fibre support paddle. The minimum pitch is approximately 40 $\\mu$m. The detector is also equipped with one n-on-p module. The detectors are operated in vacuum and a...
Vertexing and Tracking Software at Belle II
Schlüter, Tobias
2014-01-01
Belle II is a $B$ factory experiment aiming to start physics data taking in 2017. It is currently being set up at the SuperKEKB accelerator at the KEK facility in Tsukuba (Japan), an asymmetric $e^+e^-$ collider which aims to achieve an unprecedented instantaneous luminosity of $8\\cdot10^{35} \\textrm{Hz}/\\textrm{cm}^2$. This forty-fold increase over predecessor experiments is achieved by employing a novel nano-beam scheme. Originally developed for the now-defunct SuperB experiment, this scheme allows a significant increase in luminosity at only modest increases of beam currents. Challenges for the vertex detector result from increased data and background rates. At full luminosity, physics data will be recorded at a rate of $30\\,\\textrm{kHz}$. The radiation-hard DEPFET-sensors of the innermost layer of the vertex detector will be read out employing a novel data-reduction scheme using selective detector read out based on online reconstruction of event data. Belle II uses a software framework in which data handl...
The Construction of Spin Foam Vertex Amplitudes
Directory of Open Access Journals (Sweden)
Eugenio Bianchi
2013-01-01
Full Text Available Spin foam vertex amplitudes are the key ingredient of spin foam models for quantum gravity. These fall into the realm of discretized path integral, and can be seen as generalized lattice gauge theories. They can be seen as an attempt at a 4-dimensional generalization of the Ponzano-Regge model for 3d quantum gravity. We motivate and review the construction of the vertex amplitudes of recent spin foam models, giving two different and complementary perspectives of this construction. The first proceeds by extracting geometric configurations from a topological theory of the BF type, and can be seen to be in the tradition of the work of Barrett, Crane, Freidel and Krasnov. The second keeps closer contact to the structure of Loop Quantum Gravity and tries to identify an appropriate set of constraints to define a Lorentz-invariant interaction of its quanta of space. This approach is in the tradition of the work of Smolin, Markopoulous, Engle, Pereira, Rovelli and Livine.
Vertex Sparsifiers and Abstract Rounding Algorithms
Charikar, Moses; Li, Shi; Moitra, Ankur
2010-01-01
The notion of vertex sparsification is introduced in \\cite{M}, where it was shown that for any graph $G = (V, E)$ and a subset of $k$ terminals $K \\subset V$, there is a polynomial time algorithm to construct a graph $H = (K, E_H)$ on just the terminal set so that simultaneously for all cuts $(A, K-A)$, the value of the minimum cut in $G$ separating $A$ from $K -A$ is approximately the same as the value of the corresponding cut in $H$. We give the first super-constant lower bounds for how well a cut-sparsifier $H$ can simultaneously approximate all minimum cuts in $G$. We prove a lower bound of $\\Omega(\\log^{1/4} k)$ -- this is polynomially-related to the known upper bound of $O(\\log k/\\log \\log k)$. This is an exponential improvement on the $\\Omega(\\log \\log k)$ bound given in \\cite{LM} which in fact was for a stronger vertex sparsification guarantee, and did not apply to cut sparsifiers. Despite this negative result, we show that for many natural problems, we do not need to incur a multiplicative penalty fo...
Directory of Open Access Journals (Sweden)
Henschel Sebastian
2015-01-01
Full Text Available Dynamic crack initiation with crack-tip loading rates of K̇ ≈ 2.106MPa√ms-1 in a high strength G42CrMoS4 steel was investigated. To this end, a previously developed split Hopkinson pressure bar with four-point bending was utilised. V-notched and pre-cracked Charpy specimens were tested. The detection of dynamic crack initiation was performed by analysing the dynamic force equilibrium between the incident and the transmission bar. Additionally, the signal of a near-field strain gauge and high-speed photography were used to determine the instant of crack initiation. To account for vibrations of the sample, a dynamic analysis of the stress intensity factor was performed. The dynamic and static analyses of the tests produced nearly the same results when a force equilibrium was achieved. Fracture-surface analysis revealed that elongated MnS inclusions strongly affected both the dynamic crack initiation and growth. Blunting of the precrack did not take place when a group of MnS inclusions was located directly at the precrack tip. Due to the direction of the elongated MnS inclusions perpendicular to the direction of crack growth, the crack could be deflected. The comparison with a 42CrMo4 steel without elongated MnS inclusions revealed the detrimental effect in terms of resistance to crack initiation. Taking the loading-rate dependency into consideration, it was shown that there was no pronounced embrittlement due to the high loading rates.
Renormalization Group (RG) in Turbulence: Historical and Comparative Perspective
Zhou, Ye; McComb, W. David; Vahala, George
1997-01-01
The term renormalization and renormalization group are explained by reference to various physical systems. The extension of renormalization group to turbulence is then discussed; first as a comprehensive review and second concentrating on the technical details of a few selected approaches. We conclude with a discussion of the relevance and application of renormalization group to turbulence modelling.
Renormalization algorithm with graph enhancement
Hübener, R; Hartmann, L; Dür, W; Plenio, M B; Eisert, J
2011-01-01
We present applications of the renormalization algorithm with graph enhancement (RAGE). This analysis extends the algorithms and applications given for approaches based on matrix product states introduced in [Phys. Rev. A 79, 022317 (2009)] to other tensor-network states such as the tensor tree states (TTS) and projected entangled pair states (PEPS). We investigate the suitability of the bare TTS to describe ground states, showing that the description of certain graph states and condensed matter models improves. We investigate graph-enhanced tensor-network states, demonstrating that in some cases (disturbed graph states and for certain quantum circuits) the combination of weighted graph states with tensor tree states can greatly improve the accuracy of the description of ground states and time evolved states. We comment on delineating the boundary of the classically efficiently simulatable states of quantum many-body systems.
Renormalization group analysis of turbulence
Smith, Leslie M.
1989-01-01
The objective is to understand and extend a recent theory of turbulence based on dynamic renormalization group (RNG) techniques. The application of RNG methods to hydrodynamic turbulence was explored most extensively by Yakhot and Orszag (1986). An eddy viscosity was calculated which was consistent with the Kolmogorov inertial range by systematic elimination of the small scales in the flow. Further, assumed smallness of the nonlinear terms in the redefined equations for the large scales results in predictions for important flow constants such as the Kolmogorov constant. It is emphasized that no adjustable parameters are needed. The parameterization of the small scales in a self-consistent manner has important implications for sub-grid modeling.
Multilogarithmic velocity renormalization in graphene
Sharma, Anand; Kopietz, Peter
2016-06-01
We reexamine the effect of long-range Coulomb interactions on the quasiparticle velocity in graphene. Using a nonperturbative functional renormalization group approach with partial bosonization in the forward scattering channel and momentum transfer cutoff scheme, we calculate the quasiparticle velocity, v (k ) , and the quasiparticle residue, Z , with frequency-dependent polarization. One of our most striking results is that v (k ) ∝ln[Ck(α ) /k ] where the momentum- and interaction-dependent cutoff scale Ck(α ) vanishes logarithmically for k →0 . Here k is measured with respect to one of the charge neutrality (Dirac) points and α =2.2 is the strength of dimensionless bare interaction. Moreover, we also demonstrate that the so-obtained multilogarithmic singularity is reconcilable with the perturbative expansion of v (k ) in powers of the bare interaction.
Gauge invariance and holographic renormalization
Directory of Open Access Journals (Sweden)
Keun-Young Kim
2015-10-01
Full Text Available We study the gauge invariance of physical observables in holographic theories under the local diffeomorphism. We find that gauge invariance is intimately related to the holographic renormalization: the local counter terms defined in the boundary cancel most of gauge dependences of the on-shell action as well as the divergences. There is a mismatch in the degrees of freedom between the bulk theory and the boundary one. We resolve this problem by noticing that there is a residual gauge symmetry (RGS. By extending the RGS such that it satisfies infalling boundary condition at the horizon, we can understand the problem in the context of general holographic embedding of a global symmetry at the boundary into the local gauge symmetry in the bulk.
Renormalization of two-dimensional quantum electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Casana S, Rodolfo; Dias, Sebastiao A
1997-12-01
The Schwinger model, when quantized in a gauge non-invariant way exhibits a dependence on a parameter {alpha} (the Jackiw-Rajaraman parameter) in a way which is analogous to the case involving chiral fermions (the chiral Schwinger model). For all values of a {alpha}1, there are divergences in the fermionic Green`s functions. We propose a regularization of the generating functional Z [{eta}, {eta}, J] and we use it to renormalize the theory to one loop level, in a semi-perturbative sense. At the end of the renormalization procedure we find an implicit dependence of {alpha} on the renormalization scale {mu}. (author) 26 refs.
Mass Renormalization in String Theory: General States
Pius, Roji; Sen, Ashoke
2014-01-01
In a previous paper we described a procedure for computing the renormalized masses and S-matrix elements in bosonic string theory for a special class of massive states which do not mix with unphysical states under renormalization. In this paper we extend this result to general states in bosonic string theory, and argue that only the squares of renormalized physical masses appear as the locations of the poles of the S-matrix of other physical states. We also discuss generalizations to Neveu-Schwarz sector states in heterotic and superstring theories.
Aspects of Galileon non-renormalization
Energy Technology Data Exchange (ETDEWEB)
Goon, Garrett [Department of Applied Mathematics and Theoretical Physics, Cambridge University,Wilberforce Road, Cambridge, CB3 0WA (United Kingdom); Hinterbichler, Kurt [Perimeter Institute for Theoretical Physics,31 Caroline St. N, Waterloo, Ontario, N2L 2Y5 (Canada); Joyce, Austin [Enrico Fermi Institute and Kavli Institute for Cosmological Physics, University of Chicago,S. Ellis Avenue, Chicago, IL 60637 (United States); Trodden, Mark [Center for Particle Cosmology, Department of Physics and Astronomy,University of Pennsylvania,S. 33rd Street, Philadelphia, PA 19104 (United States)
2016-11-18
We discuss non-renormalization theorems applying to galileon field theories and their generalizations. Galileon theories are similar in many respects to other derivatively coupled effective field theories, including general relativity and P(X) theories. In particular, these other theories also enjoy versions of non-renormalization theorems that protect certain operators against corrections from self-loops. However, we argue that the galileons are distinguished by the fact that they are not renormalized even by loops of other heavy fields whose couplings respect the galileon symmetry.
Renormalizing the NN interaction with multiple subtractions
Energy Technology Data Exchange (ETDEWEB)
Timoteo, V.S. [Faculdade de Tecnologia, Universidade Estadual de Campinas, 13484-332 Limeira, SP (Brazil); Frederico, T. [Instituto Tecnologico de Aeronautica, Comando de Tecnologia Aeroespacial, 12228-900 Sao Jose dos Campos, SP (Brazil); Delfino, A. [Departamento de Fisica, Universidade Federal Fluminense, 24210-150 Niteroi, RJ (Brazil); Tomio, L. [Instituto de Fisica Teorica, Universidade Estadual Paulista, 01140-070 Sao Paulo, SP (Brazil); Szpigel, S.; Duraes, F.O. [Centro de Ciencias e Humanidades, Universidade Presbiteriana Mackenzie, 01302-907 Sao Paulo, SP (Brazil)
2010-02-15
The aim of this work is to show how to renormalize the nucleon-nucleon interaction at next-to-next-to-leading order using a systematic subtractive renormalization approach with multiple subtractions. As an example, we calculate the phase shifts for the partial waves with total angular momentum J=2. The intermediate driving terms at each recursive step as well as the renormalized T-matrix are also shown. We conclude that our method is reliable for singular potentials such as the two-pion exchange and derivative contact interactions.
Real-space renormalization yields finite correlations.
Barthel, Thomas; Kliesch, Martin; Eisert, Jens
2010-07-02
Real-space renormalization approaches for quantum lattice systems generate certain hierarchical classes of states that are subsumed by the multiscale entanglement renormalization Ansatz (MERA). It is shown that, with the exception of one spatial dimension, MERA states are actually states with finite correlations, i.e., projected entangled pair states (PEPS) with a bond dimension independent of the system size. Hence, real-space renormalization generates states which can be encoded with local effective degrees of freedom, and MERA states form an efficiently contractible class of PEPS that obey the area law for the entanglement entropy. It is further pointed out that there exist other efficiently contractible schemes violating the area law.
Subgraphs in vertex neighborhoods of K-free graphs
DEFF Research Database (Denmark)
Bang-Jensen, J.; Brandt, Stephan
2004-01-01
In a K-free graph, the neighborhood of every vertex induces a K-free subgraph. The K-free graphs with the converse property that every induced K-free subgraph is contained in the neighborhood of a vertex are characterized, based on the characterization in the case r = 3 due to Pach [8]. © 2004...
Graphs with No Induced Five-Vertex Path or Antipath
DEFF Research Database (Denmark)
Chudnovsky, Maria; Esperet, Louis; Lemoine, Laetitia
2017-01-01
We prove that a graph G contains no induced five-vertex path and no induced complement of a five-vertex path if and only if G is obtained from 5-cycles and split graphs by repeatedly applying the following operations: substitution, split unification, and split unification in the complement, where...
Fermion-Boson Vertex at Finite Chemical Potential
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; FENG Hong-Tao; HOU Feng-Yao; SUN Wei-Min
2007-01-01
Based on the Ward-Takahashi identity at finite chemical potential and Lorentz structure analysis, we generalize the Ball-Chiu vertex to the case of nonzero chemical potential and obtain the general form of the fermionboson vertex in QED at finite chemical potential.
Unquenching the three-gluon vertex: A status report
Blum, Adrian L; Huber, Markus Q; Windisch, Andreas
2015-01-01
We discuss unquenching of the three-gluon vertex via its Dyson-Schwinger equation. We review the role of Furry's theorem and present first results for the quark triangle diagrams using non-perturbatively calculated dressing functions for the quark propagator and the quark-gluon vertex.
The SVX II silicon vertex detector at CDF
Energy Technology Data Exchange (ETDEWEB)
Worm, S. [New Mexico Univ., Albuquerque, NM (United States). New Mexico Center for Particle Physics; CDF Collaboration
1996-09-01
The CDF silicon vertex detector is being upgraded for use in Run II of the Fermilab collider. The increased luminosity in Run II, coupled with the desire for increased acceptance and secondary vertex triggering, necessitates a complete redesign of the previous generation tracker. Details of the design are described.
On-shell two-loop three-gluon vertex
Davydychev, A I
1999-01-01
The two-loop three-gluon vertex is calculated in an arbitrary covariant gauge, in the limit when two of the gluons are on the mass shell. The corresponding two-loop results for the ghost-gluon vertex are also obtained. It is shown that the results are consistent with the Ward-Slavnov-Taylor identities.
Genus Ranges of 4-Regular Rigid Vertex Graphs.
Buck, Dorothy; Dolzhenko, Egor; Jonoska, Nataša; Saito, Masahico; Valencia, Karin
2015-01-01
A rigid vertex of a graph is one that has a prescribed cyclic order of its incident edges. We study orientable genus ranges of 4-regular rigid vertex graphs. The (orientable) genus range is a set of genera values over all orientable surfaces into which a graph is embedded cellularly, and the embeddings of rigid vertex graphs are required to preserve the prescribed cyclic order of incident edges at every vertex. The genus ranges of 4-regular rigid vertex graphs are sets of consecutive integers, and we address two questions: which intervals of integers appear as genus ranges of such graphs, and what types of graphs realize a given genus range. For graphs with 2n vertices (n > 1), we prove that all intervals [a, b] for all a genus ranges. For graphs with 2n - 1 vertices (n ≥ 1), we prove that all intervals [a, b] for all a genus ranges. We also provide constructions of graphs that realize these ranges.
Artificial Spin-Ice and Vertex Models
Cugliandolo, Leticia F.
2017-01-01
In classical and quantum frustrated magnets the interactions in combination with the lattice structure impede the spins to order in optimal configurations at zero temperature. The theoretical interest in their classical realisations has been boosted by the artificial manufacture of materials with these properties, that are of flexible design. This note summarises work on the use of vertex models to study bidimensional spin-ices samples, done in collaboration with R. A. Borzi, M. V. Ferreyra, L. Foini, G. Gonnella, S. A. Grigera, P. Guruciaga, D. Levis, A. Pelizzola and M. Tarzia, in recent years. It is an invited contribution to a J. Stat. Mech. special issue dedicated to the memory of Leo P. Kadanoff.
The Lorentzian proper vertex amplitude: Asymptotics
Engle, Jonathan; Zipfel, Antonia
2015-01-01
In previous work, the Lorentzian proper vertex amplitude for a spin-foam model of quantum gravity was derived. In the present work, the asymptotics of this amplitude are studied in the semi-classical limit. The starting point of the analysis is an expression for the amplitude as an action integral with action differing from that in the EPRL case by an extra `projector' term which scales linearly with spins only in the asymptotic limit. New tools are introduced to generalize stationary phase methods to this case. For the case of boundary data which can be glued to a non-degenerate Lorentzian 4-simplex, the asymptotic limit of the amplitude is shown to equal the single Feynman term, showing that the extra term in the asymptotics of the EPRL amplitude has been eliminated.
Weight Representations of Admissible Affine Vertex Algebras
Arakawa, Tomoyuki; Futorny, Vyacheslav; Ramirez, Luis Enrique
2017-08-01
For an admissible affine vertex algebra {V_k{(\\mathfrak{g})}} of type A, we describe a new family of relaxed highest weight representations of {V_k{(\\mathfrak{g})}}. They are simple quotients of representations of the affine Kac-Moody algebra {\\widehat{\\mathfrak{g}}} induced from the following {\\mathfrak{g}}-modules: (1) generic Gelfand-Tsetlin modules in the principal nilpotent orbit, in particular all such modules induced from {\\mathfrak{sl}_2}; (2) all Gelfand-Tsetlin modules in the principal nilpotent orbit that are induced from {\\mathfrak{sl}_3}; (3) all simple Gelfand-Tsetlin modules over {\\mathfrak{sl}_3}. This in particular gives the classification of all simple positive energy weight representations of {V_k{(\\mathfrak{g})}} with finite dimensional weight spaces for {\\mathfrak{g}=\\mathfrak{sl}_3}.
Vertex Nomination via Content and Context
Coppersmith, Glen A
2012-01-01
If I know of a few persons of interest, how can a combination of human language technology and graph theory help me find other people similarly interesting? If I know of a few people committing a crime, how can I determine their co-conspirators? Given a set of actors deemed interesting, we seek other actors who are similarly interesting. We use a collection of communications encoded as an attributed graph, where vertices represents actors and edges connect pairs of actors that communicate. Attached to each edge is the set of documents wherein that pair of actors communicate, providing content in context - the communication topic in the context of who communicates with whom. In these documents, our identified interesting actors communicate amongst each other and with other actors whose interestingness is unknown. Our objective is to nominate the most likely interesting vertex from all vertices with unknown interestingness. As an illustrative example, the Enron email corpus consists of communications between ac...
The upgrade of the LHCb Vertex Locator
Bird, T
2014-01-01
The LHCb experiment is set for a significant upgrade, which will be ready for Run~3 of the LHC in 2020. This upgrade will allow LHCb to run at a significantly higher instantaneous luminosity and collect an integrated luminosity of $50\\,\\text{fb}^{-1}$ by the end of Run~4. In this process the Vertex locator (VELO) detector will be upgraded to a pixel-based silicon detector. The upgraded VELO will improve upon the current detector by being closer to the beam and having lower material modules with microchannel cooling and a thinner RF-foil. Simulations have shown that it will maintain its excellent performance, even after the radiation damage caused by collecting an integrated luminosity of $50\\,\\text{fb}^{-1}$.
Primary Vertex Reconstruction for Upgrade at LHCb
Wanczyk, Joanna
2016-01-01
The aim of the LHCb experiment is the study of beauty and charm hadron decays with the main focus on CP violating phenomena and searches for physics beyond the Standard Model through rare decays. At the present, the second data taking period is ongoing, which is called Run II. After 2018 during the long shutdown, the replacement of signicant parts of the LHCb detector is planned. One of main changes is upgrade of the present software and hardware trigger to a more rapid full software trigger. Primary Vertex (PV) is a basis for the further tracking and it is sensitive to the LHC running conditions, which are going to change for the Upgrade. In particular, the center-of-mass collision energy should reach the maximum value of 14 TeV. As a result the quality of the reconstruction has to be studied and the reconstruction algorithms have to be optimized.
Renormalization theory and ultraviolet stability for scalar fields via renormalization group methods
Energy Technology Data Exchange (ETDEWEB)
Gallavotti, G.
1985-04-01
A self-contained analysis is given of the simplest quantum fields from the renormalization group point of view: multiscale decomposition, general renormalization theory, resummations of renormalized series via equations of the Callan-Symanzik type, asymptotic freedom, and proof of ultraviolet stability for sine-Gordon fields in two dimensions and for other super-renormalizable scalar fields. Renormalization in four dimensions (Hepp's theorem and the De Calan--Rivasseau nexclamation bound) is presented and applications are made to the Coulomb gases in two dimensions and to the convergence of the planar graph expansions in four-dimensional field theories (t' Hooft--Rivasseau theorem).
Exact Renormalization of Massless QED2
Casana, R; Casana, Rodolfo; Dias, Sebastiao Alves
2001-01-01
We perform the exact renormalization of two-dimensional massless gauge theories. Using these exact results we discuss the cluster property and confinement in both the anomalous and chiral Schwinger models.
Exact Renormalization of Massless QED2
Casana, Rodolfo; Dias, Sebastião Alves
We perform the exact renormalization of two-dimensional massless gauge theories. Using these exact results we discuss the cluster property and confinement in both the anomalous and chiral Schwinger models.
Efimov physics from a renormalization group perspective
Hammer, Hans-Werner; Platter, Lucas
2011-01-01
We discuss the physics of the Efimov effect from a renormalization group viewpoint using the concept of limit cycles. Furthermore, we discuss recent experiments providing evidence for the Efimov effect in ultracold gases and its relevance for nuclear systems.
Efimov physics from a renormalization group perspective.
Hammer, Hans-Werner; Platter, Lucas
2011-07-13
We discuss the physics of the Efimov effect from a renormalization group viewpoint using the concept of limit cycles. Furthermore, we discuss recent experiments providing evidence for the Efimov effect in ultracold gases and its relevance for nuclear systems.
Lectures on the functional renormalization group method
Polonyi, J
2001-01-01
These introductory notes are about functional renormalization group equations and some of their applications. It is emphasised that the applicability of this method extends well beyond critical systems, it actually provides us a general purpose algorithm to solve strongly coupled quantum field theories. The renormalization group equation of F. Wegner and A. Houghton is shown to resum the loop-expansion. Another version, due to J. Polchinski, is obtained by the method of collective coordinates and can be used for the resummation of the perturbation series. The genuinely non-perturbative evolution equation is obtained in a manner reminiscent of the Schwinger-Dyson equations. Two variants of this scheme are presented where the scale which determines the order of the successive elimination of the modes is extracted from external and internal spaces. The renormalization of composite operators is discussed briefly as an alternative way to arrive at the renormalization group equation. The scaling laws and fixed poin...
Improved Monte Carlo Renormalization Group Method
Gupta, R.; Wilson, K. G.; Umrigar, C.
1985-01-01
An extensive program to analyze critical systems using an Improved Monte Carlo Renormalization Group Method (IMCRG) being undertaken at LANL and Cornell is described. Here we first briefly review the method and then list some of the topics being investigated.
Towards Holographic Renormalization of Fake Supergravity
Borodatchenkova, Natalia; Mueck, Wolfgang
2008-01-01
A step is made towards generalizing the method of holographic renormalization to backgrounds which are not asymptotically AdS, corresponding to a dual gauge theory which has logarithmically running couplings even in the ultraviolet. A prime example is the background of Klebanov-Strassler (KS). In particular, a recipe is given how to calculate renormalized two-point functions for the operators dual to the bulk scalars. The recipe makes use of gauge-invariant variables for the fluctuations around the background and works for any bulk theory of the fake supergravity type. It elegantly incorporates the renormalization scheme dependence of local terms in the correlators. Before applying the method to the KS theory, it is verified that known results in asymptotically AdS backgrounds are reproduced. Finally, some comments on the calculation of renormalized vacuum expectation values are made.
Renormalization-group improved inflationary scenarios
Pozdeeva, E O
2016-01-01
The possibility to construct an inflationary scenario for renormalization-group improved potentials corresponding to the Higgs sector of quantum field models is investigated. Taking into account quantum corrections to the renormalization-group potential which sums all leading logs of perturbation theory is essential for a successful realization of the inflationary scenario, with very reasonable parameters values. The scalar electrodynamics inflationary scenario thus obtained are seen to be in good agreement with the most recent observational data.
Renormalization-group improved inflationary scenarios
Pozdeeva, E. O.; Vernov, S. Yu.
2017-03-01
The possibility to construct an inflationary scenario for renormalization-group improved potentials corresponding to the Higgs sector of quantum field models is investigated. Taking into account quantum corrections to the renormalization-group potential which sums all leading logs of perturbation theory is essential for a successful realization of the inflationary scenario, with very reasonable parameters values. The scalar electrodynamics inflationary scenario thus obtained are seen to be in good agreement with the most recent observational data.
Relativistic causality and position space renormalization
Ivan Todorov
2016-01-01
The paper gives a historical survey of the causal position space renormalization with a special attention to the role of Raymond Stora in the development of this subject. Renormalization is reduced to subtracting the pole term in analytically regularized primitively divergent Feynman amplitudes. The identification of residues with "quantum periods" and their relation to recent developments in number theory are emphasized. We demonstrate the possibility of integration over internal vertices (t...
Renormalization in Periodically Driven Quantum Dots.
Eissing, A K; Meden, V; Kennes, D M
2016-01-15
We report on strong renormalization encountered in periodically driven interacting quantum dots in the nonadiabatic regime. Correlations between lead and dot electrons enhance or suppress the amplitude of driving depending on the sign of the interaction. Employing a newly developed flexible renormalization-group-based approach for periodic driving to an interacting resonant level we show analytically that the magnitude of this effect follows a power law. Our setup can act as a non-Markovian, single-parameter quantum pump.
Non-perturbative quark mass renormalization
Capitani, S.; Luescher, M.; Sint, S.; Sommer, R.; Weisz, P.; Wittig, H.
1998-01-01
We show that the renormalization factor relating the renormalization group invariant quark masses to the bare quark masses computed in lattice QCD can be determined non-perturbatively. The calculation is based on an extension of a finite-size technique previously employed to compute the running coupling in quenched QCD. As a by-product we obtain the $\\Lambda$--parameter in this theory with completely controlled errors.
Higher loop renormalization of fermion bilinear operators
Skouroupathis, A
2007-01-01
We compute the two-loop renormalization functions, in the RI' scheme, of local bilinear quark operators $\\bar\\psi\\Gamma\\psi$, where $\\Gamma$ denotes the Scalar and Pseudoscalar Dirac matrices, in the lattice formulation of QCD. We consider both the flavor non-singlet and singlet operators; the latter, in the scalar case, leads directly to the two-loop fermion mass renormalization, $Z_m$. As a prerequisite for the above, we also compute the quark field renormalization, $Z_\\psi$, up to two loops. We use the clover action for fermions and the Wilson action for gluons. Our results are given as a polynomial in $c_{SW}$, in terms of both the renormalized and bare coupling constant, in the renormalized Feynman gauge. We also confirm the 1-loop renormalization functions, for generic gauge. A longer write-up of the present work, including the conversion of our results to the MSbar scheme and a generalization to arbitrary fermion representations, can be found in arXiv:0707.2906 .
Locking mechanisms in degree-4 vertex origami structures
Fang, Hongbin; Li, Suyi; Xu, Jian; Wang, K. W.
2016-04-01
Origami has emerged as a potential tool for the design of mechanical metamaterials and metastructures whose novel properties originate from their crease patterns. Most of the attention in origami engineering has focused on the wellknown Miura-Ori, a folded tessellation that is flat-foldable for folded sheet and stacked blocks. This study advances the state of the art and expands the research field to investigate generic degree-4 vertex (4-vertex) origami, with a focus on facet-binding. In order to understand how facet-binding attributes to the mechanical properties of 4-vertex origami structures, geometries of the 4-vertex origami cells are analyzed and analytically expressed. Through repeating and stacking 4-vertex cells, origami sheets and stacked origami blocks can be constructed. Geometry analyses discover four mechanisms that will lead to the self-locking of 4-vertex origami cells, sheets, and stacked blocks: in-cell facet-binding, inlayer facet-binding, inter-layer facet binding, and in-layer and inter-layer facet-bindings. These mechanisms and the predicted self-locking phenomena are verified through 3D simulations and prototype experiments. Finally, this paper briefly introduces the unusual mechanical properties caused by the locking of 4-vertex origami structures. The research reported in this paper could foster a new breed of self-locking structures with various engineering applications.
Impact of nonlocal correlations over different energy scales: A dynamical vertex approximation study
Rohringer, G.; Toschi, A.
2016-09-01
In this paper, we investigate how nonlocal correlations affect, selectively, the physics of correlated electrons over different energy scales, from the Fermi level to the band edges. This goal is achieved by applying a diagrammatic extension of dynamical mean field theory (DMFT), the dynamical vertex approximation (D Γ A ), to study several spectral and thermodynamic properties of the unfrustrated Hubbard model in two and three dimensions. Specifically, we focus first on the low-energy regime by computing the electronic scattering rate and the quasiparticle mass renormalization for decreasing temperatures at a fixed interaction strength. This way, we obtain a precise characterization of the several steps through which the Fermi-liquid physics is progressively destroyed by nonlocal correlations. Our study is then extended to a broader energy range, by analyzing the temperature behavior of the kinetic and potential energy, as well as of the corresponding energy distribution functions. Our findings allow us to identify a smooth but definite evolution of the nature of nonlocal correlations by increasing interaction: They either increase or decrease the kinetic energy w.r.t. DMFT depending on the interaction strength being weak or strong, respectively. This reflects the corresponding evolution of the ground state from a nesting-driven (Slater) to a superexchange-driven (Heisenberg) antiferromagnet (AF), whose fingerprints are, thus, recognizable in the spatial correlations of the paramagnetic phase. Finally, a critical analysis of our numerical results of the potential energy at the largest interaction allows us to identify possible procedures to improve the ladder-based algorithms adopted in the dynamical vertex approximation.
Euclidean Epstein-Glaser renormalization
Energy Technology Data Exchange (ETDEWEB)
Keller, Kai J. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik
2009-03-15
In the framework of perturbative Algebraic Quantum Field Theory (pAQFT) I give a general construction of so-called 'Euclidean time-ordered products', i.e. algebraic versions of the Schwinger functions, for scalar quantum eld theories on spaces of Euclidean signature. This is done by generalizing the recursive construction of time-ordered products by Epstein and Glaser, originally formulated for quantum field theories on Minkowski space (MQFT). An essential input of Epstein-Glaser renormalization is the causal structure of Minkowski space. The absence of this causal structure in the Euclidean framework makes it necessary to modify the original construction of Epstein and Glaser at two points. First, the whole construction has to be performed with an only partially defined product on (interaction-) functionals. This is due to the fact that the fundamental solutions of the Helmholtz operator (-{delta}+m{sup 2}) of EQFT have a unique singularity structure, i.e. they are unique up to a smooth part. Second, one needs to (re-)introduce a (rather natural) 'Euclidean causality' condition for the recursion of Epstein and Glaser to be applicable. (orig.)
Inflation, Renormalization, and CMB Anisotropies
Agullo, I; Olmo, Gonzalo J; Parker, Leonard
2010-01-01
In single-field, slow-roll inflationary models, scalar and tensorial (Gaussian) perturbations are both characterized by a zero mean and a non-zero variance. In position space, the corresponding variance of those fields diverges in the ultraviolet. The requirement of a finite variance in position space forces its regularization via quantum field renormalization in an expanding universe. This has an important impact on the predicted scalar and tensorial power spectra for wavelengths that today are at observable scales. In particular, we find a non-trivial change in the consistency condition that relates the tensor-to-scalar ratio "r" to the spectral indices. For instance, an exact scale-invariant tensorial power spectrum, n_t=0, is now compatible with a non-zero ratio r= 0.12 +/- 0.06, which is forbidden by the standard prediction (r=-8n_t). Forthcoming observations of the influence of relic gravitational waves on the CMB will offer a non-trivial test of the new predictions.
Oono, Y.; Freed, Karl F.
1981-07-01
A conformation space renormalization group is developed to describe polymer excluded volume in single polymer chains. The theory proceeds in ordinary space in terms of position variables and the contour variable along the chain, and it considers polymers of fixed chain length. The theory is motivated along two lines. The first presents the renormalization group transformation as the means for extracting the macroscopic long wavelength quantities from the theory. An alternative viewpoint shows how the renormalization group transformation follows as a natural consequence of an attempt to correctly treat the presence of a cut-off length scale. It is demonstrated that the current configuration space renormalization method has a one-to-one correspondence with the Wilson-Fisher field theory formulation, so our method is valid to all orders in ɛ = 4-d where d is the spatial dimensionality. This stands in contrast to previous attempts at a configuration space renormalization approach which are limited to first order in ɛ because they arbitrarily assign monomers to renormalized ''blobs.'' In the current theory the real space chain conformations dictate the coarse graining transformation. The calculations are presented to lowest order in ɛ to enable the development of techniques necessary for the treatment of dynamics in Part II. The theory is presented both in terms of the simple delta function interaction as well as using realistic-type interaction potentials. This illustrates the renormalization of the interactions, the emergence of renormalized many-body interactions, and the complexity of the theta point.
van Enter, A C; Fernández, R
1999-05-01
For classical lattice systems with finite (Ising) spins, we show that the implementation of momentum-space renormalization at the level of Hamiltonians runs into the same type of difficulties as found for real-space transformations: Renormalized Hamiltonians are ill-defined in certain regions of the phase diagram.
Enter, Aernout C.D. van; Fernández, Roberto
For classical lattice systems with finite (Ising) spins, we show that the implementation of momentum-space renormalization at the level of Hamiltonians runs into the same type of difficulties as found for real-space transformations: Renormalized Hamiltonians are ill-defined in certain regions of the
Measurement of $R_{b}$ using a Vertex Mass Tag
Abe, K; Akagi, T; Allen, N J; Ash, W W; Aston, D; Baird, K G; Baltay, C; Band, H R; Barakat, M B; Baranko, G; Bardon, O; Barklow, T L; Bashindzhagian, G L; Bazarko, A O; Ben-David, R; Benvenuti, Alberto C; Bilei, G M; Bisello, D; Blaylock, G; Bogart, J R; Bolen, B; Bolton, T; Bower, G R; Brau, J E; Breidenbach, M; Bugg, W M; Burke, D; Burnett, T H; Burrows, P N; Busza, W; Calcaterra, A; Caldwell, D O; Calloway, D; Camanzi, B; Carpinelli, M; Cassell, R; Castaldi, R; Castro, A; Cavalli-Sforza, M; Chou, A; Church, E; Cohn, H O; Coller, J A; Cook, V; Cotton, R; Cowan, R F; Coyne, D G; Crawford, G; de Oliveira, A; Damerell, C J S; Daoudi, M; De Groot, N; De Sangro, R; Dell'Orso, R; Dervan, P J; Dima, M; Dong, D N; Du, P Y C; Dubois, R; Eisenstein, B I; Elia, R; Etzion, E; Fahey, S; Falciai, D; Fan, C; Fernández, J P; Fero, M J; Frey, R; Gillman, T; Gladding, G; González, S; Hart, E L; Harton, J L; Hasan, A; Hasegawa, Y; Hasuko, K; Hedges, S J; Hertzbach, S S; Hildreth, M D; Huber, J; Huffer, M E; Hughes, E W; Hwang, H; Iwasaki, Y; Jackson, D J; Jacques, P; Jaros, J A; Jiang, Z Y; Johnson, A S; Johnson, J R; Johnson, R A; Junk, T R; Kajikawa, R; Kalelkar, M; Kang, H J; Karliner, I; Kawahara, H; Kendall, H W; Kim, Y D; King, M E; King, R; Kofler, R R; Krishna, N M; Kroeger, R S; Labs, J F; Langston, M; Lath, A; Lauber, J A; Leith, D W G S; Lia, V; Liu, M X; Liu, X; Loreti, M; Lu, A; Lynch, H L; Ma, J; Mancinelli, G; Manly, S; Mantovani, G C; Markiewicz, T W; Maruyama, T; Masuda, H; Mazzucato, E; McKemey, A K; Meadows, B T; Messner, R; Mockett, P M; Moffeit, K C; Moore, T B; Müller, D; Nagamine, T; Narita, S; Nauenberg, U; Neal, H; Nussbaum, M; Ohnishi, Y; Oishi, N; Onoprienko, D; Osborne, L S; Panvini, R S; Park, C H; Park, H; Pavel, T J; Peruzzi, I; Piccolo, M; Piemontese, L; Pieroni, E; Pitts, K T; Plano, R J; Prepost, R; Prescott, C Y; Punkar, G D; Quigley, J; Ratcliff, B N; Reeves, T W; Reidy, J; Reinertsen, P L; Rensing, P E; Rochester, L S; Rowson, P C; Russell, J J; Saxton, O H; Schalk, T; Schindler, R H; Schumm, B A; Schwiening, J; Sen, S; Serbo, V V; Shaevitz, M H; Shank, J T; Shapiro, G; Sherden, D J; Shmakov, K D; Simopoulos, C; Sinev, N B; Smith, S R; Smy, M B; Snyder, J A; Stängle, H; Stamer, P; Steiner, H; Steiner, R; Strauss, M G; Su, D; Suekane, F; Sugiyama, A; Suzuki, S; Swartz, M; Szumilo, A; Takahashi, T; Taylor, F E; Torrence, E; Trandafir, A I; Turk, J D; Usher, T; Vavra, J; Vannini, C; Vella, E; Venuti, J P; Verdier, R; Verdini, P G; Wagner, D L; Wagner, S R; Waite, A P; Watts, S J; Weidemann, A W; Weiss, E R; Whitaker, J S; White, S L; Wickens, F J; Williams, D C; Williams, S H; Willocq, S; Wilson, R J; Wisniewski, W J; Woods, M; Word, G B; Wyss, J; Yamamoto, R K; Yamartino, J M; Yang, X; Yashima, J; Yellin, S J; Young, C C; Yuta, H; Zapalac, G; Zdarko, R W; Zhou, J
1998-01-01
We report a new measurement of Rb = Gamma(Z0->b-bbar) / Gamma(Z0->hadrons) using a double tag technique, where the b hemisphere selection is based on the reconstructed mass of the B hadron decay vertex. The measurement was performed using a sample of 130k hadronic Z0 events, collected with the SLD at the SLC. The method utilizes the 3-D vertexing abilities of the CCD pixel vertex detector and the small stable SLC beams to obtain a high b-tagging efficiency and purity. We obtain Rb=0.2142+/-0.0034(stat.)+/-0.0015(syst.)+/-0.0002(R_c).
Quark-gluon vertex in arbitrary gauge and dimension
Davydychev, A I; Saks, L
2001-01-01
One-loop off-shell contributions to the quark-gluon vertex are calculated, in an arbitrary covariant gauge and in arbitrary space-time dimension, including quark-mass effects. It is shown how one can get results for all on-shell limits of interest directly from the off-shell expressions. In order to demonstrate that the Ward-Slavnov-Taylor identity for the quark-gluon vertex is satisfied, we have also calculated the corresponding one-loop contribution involving the quark-quark-ghost-ghost vertex.
Animation Visualization for Vertex Coloring of Polyhedral Graphs
Directory of Open Access Journals (Sweden)
Hidetoshi Nonaka
2013-12-01
Full Text Available Vertex coloring of a graph is the assignment of labels to the vertices of the graph so that adjacent vertices have different labels. In the case of polyhedral graphs, the chromatic number is 2, 3, or 4. Edge coloring problem and face coloring problem can be converted to vertex coloring problem for appropriate polyhedral graphs. We have been developed an interactive learning system of polyhedra, based on graph operations and simulated elasticity potential method, mainly for educational purpose. In this paper, we introduce a learning subsystem of vertex coloring, edge coloring and face coloring, based on minimum spanning tree and degenerated polyhedron, which is introduced in this paper.
Dynamic renormalization in the framework of nonequilibrium thermodynamics.
Ottinger, Hans Christian
2009-02-01
We show how the dynamic renormalization of nonequilibrium systems can be carried out within the general framework of nonequilibrium thermodynamics. Whereas the renormalization of Hamiltonians is well known from equilibrium thermodynamics, the renormalization of dissipative brackets, or friction matrices, is the main new feature for nonequilibrium systems. Renormalization is a reduction rather than a coarse-graining technique; that is, no new dissipative processes arise in the dynamic renormalization procedure. The general ideas are illustrated for dilute polymer solutions where, in renormalizing bead-spring chain models, dissipative hydrodynamic interactions between different smaller beads contribute to the friction coefficient of a single larger bead.
Performance of the LHCb Vertex Locator
Aaij, R; Akiba, K; Alexander, M; Ali, S; Appleby, R B; Artuso, M; Bates, A; Bay, A; Behrendt, O; Benton, J; van Beuzekom, M; Bjornstad, P M; Bogdanova, G; Borghi, S; Borgia, A; Bowcock, T J V; van den Brand, J; Brown, H; Buytaert, J; Callot, O; Carroll, J; Casse, G; Collins, P; De Capua, S; Doets, M; Donleavy, S; Dossett, D; Dumps, R; Eckstein, D; Eklund, L; Farinelli, C; Farry, S; Ferro-Luzzi, M; Frei, R; Garofoli, J; Gersabeck, M; Gershon, T; Gong, A; Gong, H; Gordon, H; Haefeli, G; Harrison, J; Heijne, V; Hennessy, K; Hulsbergen, W; Huse, T; Hutchcroft, D; Jaeger, A; Jalocha, P; Jans, E; John, M; Keaveney, J; Ketel, T; Korolev, M; Kraan, M; Lastovicka, T; Laﬀerty, G; Latham, T; Lefeuvre, G; Leﬂat, A; Liles, M; van Lysebetten, A; MacGregor, G; Marinho, F; McNulty, R; Merkin, M; Moran, D; Mountain, R; Mous, I; Mylroie-Smith, J; Needham, M; Nikitin, N; Noor, A; Oblakowska-Mucha, A; Papadelis, A; Pappagallo, M; Parkes, C; Patel, G D; Rakotomiaramanana, B; Redford, S; Reid, M; Rinnert, K; Rodrigues, E; Saavedra, A F; Schiller, M; Schneider, O; Shears, T; Silva Coutinho, R; Smith, N A; Szumlak, T; Thomas, C; van Tilburg, J; Tobin, M; Velthuis, J; Verlaat, B; Viret, S; Volkov, V; Wallace, C; Wang, J; Webber, A; Whitehead, M; Zverev, E
2014-01-01
The Vertex Locator (VELO) is a silicon microstrip detector that surrounds the proton-proton interaction region in the LHCb experiment. The performance of the detector during the first years of its physics operation is reviewed. The system is operated in vacuum, uses a bi-phase CO2 cooling system, and the sensors are moved to 7 mm from the LHC beam for physics data taking. The performance and stability of these characteristic features of the detector are described, and details of the material budget are given. The calibration of the timing and the data processing algorithms that are implemented in FPGAs are described. The system performance is fully characterised. The sensors have a signal to noise ratio of approximately 20 and a best hit resolution of 4 microns is achieved at the optimal track angle. The typical detector occupancy for minimum bias events in standard operating conditions in 2011 is around 0.5%, and the detector has less than 1% of faulty strips. The proximity of the detector to the beam means ...
The PHENIX Forward Silicon Vertex Detector
Aidala, C; Anderssen, LE; Bambaugh, A; Barron, A; Boissevain, J G; Bok, J; Boose, S; Brooks, M L; Butsyk, S; Cepeda, LM; Chacon, P; Chacon, S; Chavez, L; Cote, T; D'Agostino, C; Datta, A; DeBlasio, K; DelMonte, L; Desmond, E J; Durham, J M; Fields, D; Finger, M; Gingu, C; Gonzales, B; Haggerty, J S; Hawke, T; van Hecke, H W; Herron, M; Hoff, J; Huang, J; Jiang, X; Johnson, LT; Jonas, M; Kapustinsky, J; Key, A; Kunde, G J; LaBounty, J; Lee, D M; Lee, K B; Leitch, M J; Lenz, M; Lenz, W; Liu, M X; Lynch, D; Mannel, E; McGaughey, P L; Meles, A; Meredith, B; Nguyen, H; O'Brien, E; Pak, R; Papavassiliou, V; Pate, S; Pereira, H; Perera, G D N; Phillips, M; Pisani, R; Polizzo, S; Poncione, R J; Popule, J; Prokop, M; Purschke, M L; Purwar, A K; Ronzhina, N; Silva, C L; Slunecka, M; Smith, R; Sondheim, W E; Spendier, K; Stoffer, M; Tennant, E; Thomas, D; Tomasek, M; Veicht, A; Vrba, V; Wang, X R; Wei, F; Winter, D; Yarema, R; You, Z; Zimmerman, A; Zimmerman, T
2013-01-01
A new silicon detector has been developed to provide the PHENIX experiment with precise charged particle tracking at forward and backward rapidity. The Forward Silicon Vertex Tracker (FVTX) was installed in PHENIX prior to the 2012 run period of the Relativistic Heavy Ion Collider (RHIC). The FVTX is composed of two annular endcaps, each with four stations of silicon mini-strip sensors, covering a rapidity range of $1.2<|\\eta|<2.2$ that closely matches the two existing PHENIX muon arms. Each station consists of 48 individual silicon sensors, each of which contains two columns of mini-strips with 75 $\\mu$m pitch in the radial direction and lengths in the $\\phi$ direction varying from 3.4 mm at the inner radius to 11.5 mm at the outer radius. The FVTX has approximately 0.54 million strips in each endcap. These are read out with FPHX chips, developed in collaboration with Fermilab, which are wire bonded directly to the mini-strips. The maximum strip occupancy reached in central Au-Au collisions is approxim...
Vertex micromagnetic energy in artificial square ice
Perrin, Yann; Canals, Benjamin; Rougemaille, Nicolas
2016-10-01
Artificial arrays of interacting magnetic elements provide an uncharted arena in which the physics of magnetic frustration and magnetic monopoles can be observed in real space and in real time. These systems offer the formidable opportunity to investigate a wide range of collective magnetic phenomena with a lab-on-chip approach and to explore various theoretical predictions from spin models. Here, we study artificial square ice systems numerically and use micromagnetic simulations to understand how the geometrical parameters of the individual magnetic elements affect the energy levels of an isolated square vertex. More specifically, we address the question of whether the celebrated square ice model could be made relevant for artificial square ice systems. Our work reveals that tuning the geometry alone should not allow the experimental realization of the square ice model when using nanomagnets coupled through the magnetostatic interaction. However, low-aspect ratios combined with small gaps separating neighboring magnetic elements of moderated thickness might permit approaching the ideal case where the degeneracy of the ice rule states is recovered.
Radiation damage in the LHCb Vertex Locator
Affolder, A; Alexander, M; Ali, S; Artuso, M; Benton, J; van Beuzekom, M; Bjørnstad, P M; Bogdanova, G; Borghi, S; Bowcock, T J V; Brown, H; Buytaert, J; Casse, G; Collins, P; De Capua, S; Dossett, D; Eklund, L; Farinelli, C; Garofoli, J; Gersabeck, M; Gershon, T; Gordon, H; Harrison, J; Heijne, V; Hennessy, K; Hutchcroft, D; Jans, E; John, M; Ketel, T; Lafferty, G; Latham, T; Leflat, A; Liles, M; Moran, D; Mous, I; Oblakowska-Mucha, A; Parkes, C; Patel, G D; Redford, S; Reid, M M; Rinnert, K; Rodrigues, E; Schiller, M; Szumlak, T; Thomas, C; Velthuis, J; Volkov, V; Webber, A D; Whitehead, M; Zverev, E
2013-01-01
The LHCb Vertex Locator (VELO) is a silicon strip detector designed to reconstruct charged particle trajectories and vertices produced at the LHCb interaction region. During the first two years of data collection, the 84 VELO sensors have been exposed to a range of fluences up to a maximum value of approximately $\\rm{45 \\times 10^{12}\\,1\\,MeV}$ neutron equivalent ($\\rm{1\\,MeV\\,n_{eq}}$). At the operational sensor temperature of approximately $-7\\,^{\\circ}\\rm{C}$, the average rate of sensor current increase is 18$\\mu$ A per $\\rm{fb^{-1}}$, in excellent agreement with predictions. The silicon effective bandgap has been determined using current versus temperature scan data after irradiation, with an average value of $E_{g}=1.16\\pm0.03\\pm0.04\\,\\rm{eV}$ obtained. The first observation of n-on-n sensor type inversion at the LHC has been made, occurring at a fluence of around $15 \\times 10 ^{12}$ of $1\\,\\rm{MeV\\,n_{eq}}$. The only n-on-p sensors in use at the LHC have also been studied. With an initial fluence of ap...
Torus Knots and the Topological Vertex
Jockers, Hans; Soroush, Masoud
2012-01-01
We propose a class of toric Lagrangian A-branes on the resolved conifold that is suitable to describe torus knots on S^3. The key role is played by the SL(2,Z) transformation, which generates a general torus knot from the unknot. Applying the topological vertex to the proposed A-branes, we rederive the colored HOMFLY polynomials for torus knots, in agreement with the Rosso and Jones formula. We show that our A-model construction is mirror symmetric to the B-model analysis of Brini, Eynard and Marino. Comparing to the recent proposal by Aganagic and Vafa for knots on S^3, we demonstrate that the disk amplitude of the A-brane associated to any knot is sufficient to reconstruct the entire B-model spectral curve. Finally, the construction of toric Lagrangian A-branes is generalized to other local toric Calabi-Yau geometries, which paves the road to study knots in other three-manifolds such as lens spaces.
Status of the LHCb VErtex LOcator
Palacios, J P
2003-01-01
LHCb is a single arm spectrometer at the LHC. It is dedicated to the study of CP violation in the B-hadron system. The VErtex LOcator (VELO) is a silicon microstrip detector providing accurate measurements of event primary and secondary vertices, impact parameters, and tracks. The second level trigger decision of LHCb is mainly based on information from a full readout of the VELO. This document gives a general introduction to LHCb as a context for a more extensive description of the VELO. The VELO design emphasises the need for precise reconstruction of tracks down to momenta of a few GeV. The VELO operates inside the LHC beam-pipe, and the sensors, the hybrids, and the foil separating the primary and secondary vacuua must be built with the minimum possible material. The R-$\\phi$ strip layout is optimised for efficient trigger operation and precise measurements at the smallest radii. The performance must be maintained in the harsh radiation environment close to the LHC beams. These issues have led to a choice...
Dynamical Vertex Approximation for the Hubbard Model
Toschi, Alessandro
A full understanding of correlated electron systems in the physically relevant situations of three and two dimensions represents a challenge for the contemporary condensed matter theory. However, in the last years considerable progress has been achieved by means of increasingly more powerful quantum many-body algorithms, applied to the basic model for correlated electrons, the Hubbard Hamiltonian. Here, I will review the physics emerging from studies performed with the dynamical vertex approximation, which includes diagrammatic corrections to the local description of the dynamical mean field theory (DMFT). In particular, I will first discuss the phase diagram in three dimensions with a special focus on the commensurate and incommensurate magnetic phases, their (quantum) critical properties, and the impact of fluctuations on electronic lifetimes and spectral functions. In two dimensions, the effects of non-local fluctuations beyond DMFT grow enormously, determining the appearance of a low-temperature insulating behavior for all values of the interaction in the unfrustrated model: Here the prototypical features of the Mott-Hubbard metal-insulator transition, as well as the existence of magnetically ordered phases, are completely overwhelmed by antiferromagnetic fluctuations of exponentially large extension, in accordance with the Mermin-Wagner theorem. Eventually, by a fluctuation diagnostics analysis of cluster DMFT self-energies, the same magnetic fluctuations are identified as responsible for the pseudogap regime in the holed-doped frustrated case, with important implications for the theoretical modeling of the cuprate physics.
On vertex-coloring edge-weighting of graphs
Institute of Scientific and Technical Information of China (English)
Honglian LU; Xu YANG; Qinglin YU
2009-01-01
A k-edge-weighting w of a graph G is an assignment of an integer weight, w(e) ∈ {1,..., k}, to each edge e. An edge-weighting naturally induces a vertex coloring c by defining e(u) = ∑eЭuw(e) for every u ∈ V(G). A k-edge-weighting of a graph G is vertex-coloring if the induced coloring c is proper, I.e., c(u)≠c(v) for any edge uv ∈ E(G). When k ≡ 2 (mod 4)and k≥ 6, we prove that if G is k-colorable and 2-connected, δ(G) ≥ k - 1, then G admits a vertex-coloring k-edge-weighting. We also obtain several sufficient conditions for graphs to be vertex-coloring k-edge-weighting.
The $\\omega DD$ vertex in a Sum Rule approach
Holanda, L B; Mihara, A
2007-01-01
The study of charmonium dissociation in heavy ion collisions is generally performed in the framework of effective Lagrangians with meson exchange. Some studies are also developed with the intention of calculate form factors and coupling constants related with charmed and light mesons. These quantities are important in the evaluation of charmonium cross sections. In this paper we present a calculation of the $\\omega DD$ vertex that is a possible interaction vertex in some meson-exchange models spread in the literature. We used the standard method of QCD Sum Rules in order to obtain the vertex form factor as a function of the transferred momentum. Our results are compatible with the value of this vertex form factor (at zero momentum transfer) obtained in the vector-meson dominance model.
A new method for counting trees with vertex partition
Institute of Scientific and Technical Information of China (English)
2008-01-01
A direct and elementary method is provided in this paper for counting trees with vertex partition instead of recursion, generating function, functional equation, Lagrange inversion, and matrix methods used before.
Assembling the last module of the vertex locator for LHCb
Maximilien Brice
2007-01-01
The 42nd and final vertex locator module is assembled in the LHCb clean room. This will be used to measure the point at which two protons in the beam collide from the tracks of particles produced in the collision.
Vertex models: from cell mechanics to tissue morphogenesis
Alt, Silvanus; Ganguly, Poulami
2017-01-01
Tissue morphogenesis requires the collective, coordinated motion and deformation of a large number of cells. Vertex model simulations for tissue mechanics have been developed to bridge the scales between force generation at the cellular level and tissue deformation and flows. We review here various formulations of vertex models that have been proposed for describing tissues in two and three dimensions. We discuss a generic formulation using a virtual work differential, and we review applications of vertex models to biological morphogenetic processes. We also highlight recent efforts to obtain continuum theories of tissue mechanics, which are effective, coarse-grained descriptions of vertex models. This article is part of the themed issue ‘Systems morphodynamics: understanding the development of tissue hardware’. PMID:28348254
Factorial Schur functions via the six vertex model
McNamara, Peter J
2009-01-01
For a particular set of Boltzmann weights and a particular boundary condition for the six vertex model in statistical mechanics, we compute explicitly the partition function and show it to be equal to a factorial Schur function.
Vertex Reconstruction in the ATLAS Experiment at the LHC
Bouhova-Thacker, E; The ATLAS collaboration; Kostyukhin, V; Liebig, W; Limper, M; Piacquadio, G; Lichard, P; Weiser, C; Wildauer, A
2009-01-01
In the harsh environment of the Large Hadron Collider at CERN (design luminosity of $10^{34}$ cm$^{-2}$ s$^{-1}$) efficient reconstruction of vertices is crucial for many physics analyses. Described in this paper are the strategies for vertex reconstruction used in the ATLAS experiment and their implementation in the software framework Athena. The algorithms for the reconstruction of primary and secondary vertices as well as for finding of photon conversions and vertex reconstruction in jets are described. A special emphasis is made on the vertex fitting with application of additional constraints. The implementation of mentioned algorithms follows a very modular design based on object-oriented C++ and use of abstract interfaces. The user-friendly concept allows event reconstruction and physics analyses to compare and optimize their choice among different vertex reconstruction strategies. The performance of implemented algorithms has been studied on a variety of Monte Carlo samples and results are presented.
Contractor renormalization group and the Haldane conjecture
Energy Technology Data Exchange (ETDEWEB)
Weinstein, Marvin
2001-05-01
The contractor renormalization group formalism (CORE) is a real-space renormalization group method which is the Hamiltonian analogue of the Wilson exact renormalization group equations. In an earlier paper [Phys. Rev. D 61, 034505 (2000)] I showed that the CORE method could be used to map a theory of free quarks and quarks interacting with gluons into a generalized frustrated Heisenberg antiferromagnet (HAF) and proposed using CORE methods to study these theories. Since generalizations of HAF's exhibit all sorts of subtle behavior which, from a continuum point of view, are related to topological properties of the theory, it is important to know that CORE can be used to extract this physics. In this paper I show that despite the folklore which asserts that all real-space renormalization group schemes are necessarily inaccurate, simple CORE computations can give highly accurate results even if one only keeps a small number of states per block and a few terms in the cluster expansion. In addition I argue that even very simple CORE computations give a much better qualitative understanding of the physics than naive renormalization group methods. In particular I show that the simplest CORE computation yields a first-principles understanding of how the famous Haldane conjecture works for the case of the spin-1/2 and spin-1 HAF.
Mirror of the refined topological vertex from a matrix model
Eynard, B
2011-01-01
We find an explicit matrix model computing the refined topological vertex, starting from its representation in terms of plane partitions. We then find the spectral curve of that matrix model, and thus the mirror symmetry of the refined vertex. With the same method we also find a matrix model for the strip geometry, and we find its mirror curve. The fact that there is a matrix model shows that the refined topological string amplitudes also satisfy the remodeling the B-model construction.
The vertex detector for the Lepton/Photon collaboration
Energy Technology Data Exchange (ETDEWEB)
Sullivan, J.P.; Boissevain, J.G.; Fox, D.; Hecke, H. van; Jacak, B.V.; Kapustinsky, J.S.; Leitch, M.J.; McGaughey, P.L.; Moss, J.M.; Sondheim, W.E. [Los Alamos National Lab., NM (United States)
1991-12-31
The conceptual design of the vertex detector for the Lepton/Photon Collaboration at RHIC is described, including simulations of its expected performance. The design consists of two con- centric layers of single-sided Si strips. The expected performance as a multiplicity detector and in measuring the pseudo-rapidity ({nu}) distribution is discussed as well as the expected vertex finding efficiency and accuracy. Various options which could be used to reduce the cost of the detector are also discussed.
R&D Challenges of a CLIC Vertex Detector
van der Kraaij, E
2010-01-01
The Compact Linear Collider (CLIC) is a concept for an electron-positron collider with a center- of-mass energy of up to 3 TeV. Given the unprecedented experimental conditions at CLIC none of the technologies available today can fulfill all requirements set for the vertex detector. At the conference these conditions and the challenges they pose for the R&D of a CLIC vertex detector were presented.
The vertex detector for the Lepton/Photon collaboration
Energy Technology Data Exchange (ETDEWEB)
Sullivan, J.P.; Boissevain, J.G.; Fox, D.; Hecke, H. van; Jacak, B.V.; Kapustinsky, J.S.; Leitch, M.J.; McGaughey, P.L.; Moss, J.M.; Sondheim, W.E. [Los Alamos National Lab., NM (United States)
1991-12-31
The conceptual design of the vertex detector for the Lepton/Photon Collaboration at RHIC is described, including simulations of its expected performance. The design consists of two con- centric layers of single-sided Si strips. The expected performance as a multiplicity detector and in measuring the pseudo-rapidity ({nu}) distribution is discussed as well as the expected vertex finding efficiency and accuracy. Various options which could be used to reduce the cost of the detector are also discussed.
Performance of the ATLAS primary vertex reconstruction algorithms
Zhang, Matt
2017-01-01
The reconstruction of primary vertices in the busy, high pile up environment of the LHC is a challenging task. The challenges and novel methods developed by the ATLAS experiment to reconstruct vertices in such environments will be presented. Such advances in vertex seeding include methods taken from medical imagining, which allow for reconstruction of very nearby vertices will be highlighted. The performance of the current vertexing algorithms using early Run-2 data will be presented and compared to results from simulation.
DISTRIBUTED VERTEX COVER ALGORITHMS FOR WIRELESS SENSOR NETWORKS
Directory of Open Access Journals (Sweden)
Vedat Kavalci
2014-01-01
Full Text Available Vertex covering has important applications for wireless sensor networks such as monitoring link failures, facility location, clustering, and data aggregation. In this study, we designed three algorithms for constructing vertex cover in wireless sensor networks. The first algorithm, which is an adaption of the Parnas & Ron’s algorithm, is a greedy approach that finds a vertex cover by using the degrees of the nodes. The second algorithm finds a vertex cover from graph matching where Hoepman’s weighted matching algorithm is used. The third algorithm firstly forms a breadth-first search tree and then constructs a vertex cover by selecting nodes with predefined levels from breadth-first tree. We show the operation of the designed algorithms, analyze them, and provide the simulation results in the TOSSIM environment. Finally we have implemented, compared and assessed all these approaches. The transmitted message count of the first algorithm is smallest among other algorithms where the third algorithm has turned out to be presenting the best results in vertex cover approximation ratio.
Renormalization group independence of Cosmological Attractors
Fumagalli, Jacopo
2017-06-01
The large class of inflationary models known as α- and ξ-attractors gives identical cosmological predictions at tree level (at leading order in inverse power of the number of efolds). Working with the renormalization group improved action, we show that these predictions are robust under quantum corrections. This means that for all the models considered the inflationary parameters (ns , r) are (nearly) independent on the Renormalization Group flow. The result follows once the field dependence of the renormalization scale, fixed by demanding the leading log correction to vanish, satisfies a quite generic condition. In Higgs inflation (which is a particular ξ-attractor) this is indeed the case; in the more general attractor models this is still ensured by the renormalizability of the theory in the effective field theory sense.
Perturbatively improving RI-MOM renormalization constants
Energy Technology Data Exchange (ETDEWEB)
Constantinou, M.; Costa, M.; Panagopoulos, H. [Cyprus Univ. (Cyprus). Dept. of Physics; Goeckeler, M. [Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics; Perlt, H.; Schiller, A. [Leipzig Univ. (Germany). Inst. fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Schhierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2013-03-15
The determination of renormalization factors is of crucial importance in lattice QCD. They relate the observables obtained on the lattice to their measured counterparts in the continuum in a suitable renormalization scheme. Therefore, they have to be computed as precisely as possible. A widely used approach is the nonperturbative Rome-Southampton method. It requires, however, a careful treatment of lattice artifacts. In this paper we investigate a method to suppress these artifacts by subtracting one-loop contributions to renormalization factors calculated in lattice perturbation theory. We compare results obtained from a complete one-loop subtraction with those calculated for a subtraction of contributions proportional to the square of the lattice spacing.
Foundations and Applications of Entanglement Renormalization
Evenbly, Glen
2011-01-01
Understanding the collective behavior of a quantum many-body system, a system composed of a large number of interacting microscopic degrees of freedom, is a key aspect in many areas of contemporary physics. However, as a direct consequence of the difficultly of the so-called many-body problem, many exotic quantum phenomena involving extended systems, such as high temperature superconductivity, remain not well understood on a theoretical level. Entanglement renormalization is a recently proposed numerical method for the simulation of many-body systems which draws together ideas from the renormalization group and from the field of quantum information. By taking due care of the quantum entanglement of a system, entanglement renormalization has the potential to go beyond the limitations of previous numerical methods and to provide new insight to quantum collective phenomena. This thesis comprises a significant portion of the research development of ER following its initial proposal. This includes exploratory stud...
Renormalized vacuum polarization of rotating black holes
Ferreira, Hugo R C
2015-01-01
Quantum field theory on rotating black hole spacetimes is plagued with technical difficulties. Here, we describe a general method to renormalize and compute the vacuum polarization of a quantum field in the Hartle-Hawking state on rotating black holes. We exemplify the technique with a massive scalar field on the warped AdS3 black hole solution to topologically massive gravity, a deformation of (2+1)-dimensional Einstein gravity. We use a "quasi-Euclidean" technique, which generalizes the Euclidean techniques used for static spacetimes, and we subtract the divergences by matching to a sum over mode solutions on Minkowski spacetime. This allows us, for the first time, to have a general method to compute the renormalized vacuum polarization (and, more importantly, the renormalized stress-energy tensor), for a given quantum state, on a rotating black hole, such as the physically relevant case of the Kerr black hole in four dimensions.
Perturbatively improving RI-MOM renormalization constants
Energy Technology Data Exchange (ETDEWEB)
Constantinou, M.; Costa, M.; Panagopoulos, H. [Cyprus Univ. (Cyprus). Dept. of Physics; Goeckeler, M. [Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics; Perlt, H.; Schiller, A. [Leipzig Univ. (Germany). Inst. fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Schhierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2013-03-15
The determination of renormalization factors is of crucial importance in lattice QCD. They relate the observables obtained on the lattice to their measured counterparts in the continuum in a suitable renormalization scheme. Therefore, they have to be computed as precisely as possible. A widely used approach is the nonperturbative Rome-Southampton method. It requires, however, a careful treatment of lattice artifacts. In this paper we investigate a method to suppress these artifacts by subtracting one-loop contributions to renormalization factors calculated in lattice perturbation theory. We compare results obtained from a complete one-loop subtraction with those calculated for a subtraction of contributions proportional to the square of the lattice spacing.
Wilsonian renormalization, differential equations and Hopf algebras
Thomas, Krajewski
2008-01-01
In this paper, we present an algebraic formalism inspired by Butcher's B-series in numerical analysis and the Connes-Kreimer approach to perturbative renormalization. We first define power series of non linear operators and propose several applications, among which the perturbative solution of a fixed point equation using the non linear geometric series. Then, following Polchinski, we show how perturbative renormalization works for a non linear perturbation of a linear differential equation that governs the flow of effective actions. Finally, we define a general Hopf algebra of Feynman diagrams adapted to iterations of background field effective action computations. As a simple combinatorial illustration, we show how these techniques can be used to recover the universality of the Tutte polynomial and its relation to the $q$-state Potts model. As a more sophisticated example, we use ordered diagrams with decorations and external structures to solve the Polchinski's exact renormalization group equation. Finally...
Self-Consistency Requirements of the Renormalization Group for Setting the Renormalization Scale
Energy Technology Data Exchange (ETDEWEB)
Brodsky, Stanley J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Wu, Xing-Gang [Chongqing Univ. (China); SLAC National Accelerator Lab., Menlo Park, CA (United States)
2012-08-07
In conventional treatments, predictions from fixed-order perturbative QCD calculations cannot be fixed with certainty due to ambiguities in the choice of the renormalization scale as well as the renormalization scheme. In this paper we present a general discussion of the constraints of the renormalization group (RG) invariance on the choice of the renormalization scale. We adopt the RG based equations, which incorporate the scheme parameters, for a general exposition of RG invariance, since they simultaneously express the invariance of physical observables under both the variation of the renormalization scale and the renormalization scheme parameters. We then discuss the self-consistency requirements of the RG, such as reflexivity, symmetry, and transitivity, which must be satisfied by the scale-setting method. The Principle of Minimal Sensitivity (PMS) requires the slope of the approximant of an observable to vanish at the renormalization point. This criterion provides a scheme-independent estimation, but it violates the symmetry and transitivity properties of the RG and does not reproduce the Gell-Mann-Low scale for QED observables. The Principle of Maximum Conformality (PMC) satisfies all of the deductions of the RG invariance - reflectivity, symmetry, and transitivity. Using the PMC, all non-conformal {β^{R}_{i}}-terms (R stands for an arbitrary renormalization scheme) in the perturbative expansion series are summed into the running coupling, and one obtains a unique, scale-fixed, scheme-independent prediction at any finite order. The PMC scales and the resulting finite-order PMC predictions are both to high accuracy independent of the choice of initial renormalization scale, consistent with RG invariance.
On Renormalizing Viscous Fluids as Models for Large Scale Structure Formation
Führer, Florian
2015-01-01
We consider renormalization of the Adhesion Model for cosmic structure formation. This is a simple model that shares many relevant features of recent approaches which add effective viscosity and noise terms to the fluid equations of Cold Dark Matter, offering itself as a pedagogical playground to study the removal of the cutoff dependence from loop integrals. We show in this context that if the viscosity and noise terms are treated as perturbative corrections to the standard eulerian perturbation theory, as is done for example in the Effective Field Theory of Large Scale Structure (EFToLSS) approach, they are necessarily non-local in time. To ensure Galilean Invariance higher order vertices related to the viscosity and the noise must be added. We explicitly show at one-loop that these terms act as counter terms for vertex diagrams, while the Ward Identities ensure that the non-local theory can be renormalized consistently. A local-in-time theory is renormalizable if the viscosity is included in the linear pro...
The functional renormalization group for interacting quantum systems with spin-orbit interaction
Energy Technology Data Exchange (ETDEWEB)
Grap, Stephan Michael [RWTH Aachen (Germany). Inst. fuer Theorie der Statistischen Physik
2013-07-15
We studied the influence of spin-orbit interaction (SOI) in interacting low dimensional quantum systems at zero temperature within the framework of the functional renormalization group (fRG). Among the several types of spin-orbit interaction the so-called Rashba spin-orbit interaction is especially intriguing for future spintronic applications as it may be tuned via external electric fields. We investigated its effect on the low energy physics of an interacting quantum wire in an applied Zeeman field which is modeled as a generalization of the extended Hubbard model. To this end we performed a renormalization group study of the two particle interaction, including the SOI and the Zeeman field exactly on the single particle level. Considering the resulting two band model, we formulated the RG equations for the two particle vertex keeping the full band structure as well as the non trivial momentum dependence of the low energy two particle scattering processes. In order to solve these equations numerically we defined criteria that allowed us to classify whether a given set of initial conditions flows towards the strongly coupled regime. We found regions in the models parameter space where a weak coupling method as the fRG is applicable and it is possible to calculate additional quantities of interest. Furthermore we analyzed the effect of the Rashba SOI on the properties of an interacting multi level quantum dot coupled to two semi in nite leads. Of special interest was the interplay with a Zeeman field and its orientation with respect to the SOI term. We found a renormalization of the spin-orbit energy which is an experimental quantity used to asses SOI effects in transport measurements, as well as renormalized effective g factors used to describe the Zeeman field dependence. In particular in asymmetrically coupled systems the large parameter space allows for rich physics which we studied by means of the linear conductance obtained via the generalized Landauer
Directory of Open Access Journals (Sweden)
Durães F.O.
2010-04-01
Full Text Available We apply the similarity renormalization group (SRG approach to evolve a nucleon-nucleon (N N interaction in leading-order (LO chiral eﬀective ﬁeld theory (ChEFT, renormalized within the framework of the subtracted kernel method (SKM. We derive a ﬁxed-point interaction and show the renormalization group (RG invariance in the SKM approach. We also compare the evolution of N N potentials with the subtraction scale through a SKM RG equation in the form of a non-relativistic Callan-Symanzik (NRCS equation and the evolution with the similarity cutoﬀ through the SRG transformation.
Alleviating the window problem in large volume renormalization schemes
Korcyl, Piotr
2017-01-01
We propose a strategy for large volume non-perturbative renormalization which alleviates the window problem by reducing cut-off effects. We perform a proof-of-concept study using position space renormalization scheme and the CLS $N_f=2+1$ ensembles generated at 5 different lattice spacings. We show that in the advocated strategy results for the renormalization constants are to a large extend independent of the specific lattice direction used to define the renormalization condition. Hence, ver...
Loop Optimization for Tensor Network Renormalization
Yang, Shuo; Gu, Zheng-Cheng; Wen, Xiao-Gang
2017-03-01
We introduce a tensor renormalization group scheme for coarse graining a two-dimensional tensor network that can be successfully applied to both classical and quantum systems on and off criticality. The key innovation in our scheme is to deform a 2D tensor network into small loops and then optimize the tensors on each loop. In this way, we remove short-range entanglement at each iteration step and significantly improve the accuracy and stability of the renormalization flow. We demonstrate our algorithm in the classical Ising model and a frustrated 2D quantum model.
Relativistic causality and position space renormalization
Todorov, Ivan
2016-11-01
The paper gives a historical survey of the causal position space renormalization with a special attention to the role of Raymond Stora in the development of this subject. Renormalization is reduced to subtracting the pole term in analytically regularized primitively divergent Feynman amplitudes. The identification of residues with "quantum periods" and their relation to recent developments in number theory are emphasized. We demonstrate the possibility of integration over internal vertices (that requires control over the infrared behavior) in the case of the massless φ4 theory and display the dilation and the conformal anomaly.
Renormalization Group independence of Cosmological Attractors
Fumagalli, Jacopo
2016-01-01
The large class of inflationary models known as $\\alpha$- and $\\xi$-attractors give identical predictions at tree level (at leading order in inverse power of the number of efolds). Working with the renormalization group improved action, we show that these predictions are robust under quantum corrections. This result follows once the field dependence of the renormalization scale, fixed by demanding the leading log correction to vanish, satisfies a quite generic condition. In Higgs inflation this is indeed the case; in the more general attractor models this is still ensured by the renormalizability of the theory in the effective field theory sense.
Renormalized Effective QCD Hamiltonian Gluonic Sector
Robertson, D G; Szczepaniak, A P; Ji, C R; Cotanch, S R
1999-01-01
Extending previous QCD Hamiltonian studies, we present a new renormalization procedure which generates an effective Hamiltonian for the gluon sector. The formulation is in the Coulomb gauge where the QCD Hamiltonian is renormalizable and the Gribov problem can be resolved. We utilize elements of the Glazek and Wilson regularization method but now introduce a continuous cut-off procedure which eliminates non-local counterterms. The effective Hamiltonian is then derived to second order in the strong coupling constant. The resulting renormalized Hamiltonian provides a realistic starting point for approximate many-body calculations of hadronic properties for systems with explicit gluon degrees of freedom.
Renormalization of Wilson operators in Minkowski space
Andra, A
1996-01-01
We make some comments on the renormalization of Wilson operators (not just vacuum -expectation values of Wilson operators), and the features which arise in Minkowski space. If the Wilson loop contains a straight light-like segment, charge renormalization does not work in a simple graph-by-graph way; but does work when certain graphs are added together. We also verify that, in a simple example of a smooth loop in Minkowski space, the existence of pairs of points which are light-like separated does not cause any extra divergences.
Novel formulations of CKM matrix renormalization
Kniehl, B A
2009-01-01
We review two recently proposed on-shell schemes for the renormalization of the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix in the Standard Model. One first constructs gauge-independent mass counterterm matrices for the up- and down-type quarks complying with the hermiticity of the complete mass matrices. Diagonalization of the latter then leads to explicit expressions for the CKM counterterm matrix, which are gauge independent, preserve unitarity, and lead to renormalized amplitudes that are non-singular in the limit in which any two quarks become mass degenerate. One of the schemes also automatically satisfies flavor democracy.
Exact Renormalization Group for Point Interactions
Eröncel, Cem
2014-01-01
Renormalization is one of the deepest ideas in physics, yet its exact implementation in any interesting problem is usually very hard. In the present work, following the approach by Glazek and Maslowski in the flat space, we will study the exact renormalization of the same problem in a nontrivial geometric setting, namely in the two dimensional hyperbolic space. Delta function potential is an asymptotically free quantum mechanical problem which makes it resemble non-abelian gauge theories, yet it can be treated exactly in this nontrivial geometry.
Automating Renormalization of Quantum Field Theories
Kennedy, A D; Rippon, T
2007-01-01
We give an overview of state-of-the-art multi-loop Feynman diagram computations, and explain how we use symbolic manipulation to generate renormalized integrals that are then evaluated numerically. We explain how we automate BPHZ renormalization using "henges" and "sectors", and give a brief description of the symbolic tensor and Dirac gamma-matrix manipulation that is required. We shall compare the use of general computer algebra systems such as Maple with domain-specific languages such as FORM, highlighting in particular memory management issues.
Random vibrational networks and the renormalization group.
Hastings, M B
2003-04-11
We consider the properties of vibrational dynamics on random networks, with random masses and spring constants. The localization properties of the eigenstates contrast greatly with the Laplacian case on these networks. We introduce several real-space renormalization techniques which can be used to describe this dynamics on general networks, drawing on strong disorder techniques developed for regular lattices. The renormalization group is capable of elucidating the localization properties, and provides, even for specific network instances, a fast approximation technique for determining the spectra which compares well with exact results.
Relativistic causality and position space renormalization
Directory of Open Access Journals (Sweden)
Ivan Todorov
2016-11-01
Full Text Available The paper gives a historical survey of the causal position space renormalization with a special attention to the role of Raymond Stora in the development of this subject. Renormalization is reduced to subtracting the pole term in analytically regularized primitively divergent Feynman amplitudes. The identification of residues with “quantum periods” and their relation to recent developments in number theory are emphasized. We demonstrate the possibility of integration over internal vertices (that requires control over the infrared behavior in the case of the massless φ4 theory and display the dilation and the conformal anomaly.
Information geometry and the renormalization group.
Maity, Reevu; Mahapatra, Subhash; Sarkar, Tapobrata
2015-11-01
Information theoretic geometry near critical points in classical and quantum systems is well understood for exactly solvable systems. Here, we show that renormalization group flow equations can be used to construct the information metric and its associated quantities near criticality for both classical and quantum systems in a universal manner. We study this metric in various cases and establish its scaling properties in several generic examples. Scaling relations on the parameter manifold involving scalar quantities are studied, and scaling exponents are identified. The meaning of the scalar curvature and the invariant geodesic distance in information geometry is established and substantiated from a renormalization group perspective.
Loop Optimization for Tensor Network Renormalization.
Yang, Shuo; Gu, Zheng-Cheng; Wen, Xiao-Gang
2017-03-17
We introduce a tensor renormalization group scheme for coarse graining a two-dimensional tensor network that can be successfully applied to both classical and quantum systems on and off criticality. The key innovation in our scheme is to deform a 2D tensor network into small loops and then optimize the tensors on each loop. In this way, we remove short-range entanglement at each iteration step and significantly improve the accuracy and stability of the renormalization flow. We demonstrate our algorithm in the classical Ising model and a frustrated 2D quantum model.
EXACT RENORMALIZATION GROUP FOR POINT INTERACTIONS
Directory of Open Access Journals (Sweden)
Osman Teoman Turgut Teoman Turgut
2014-04-01
Full Text Available Renormalization is one of the deepest ideas in physics, yet its exact implementation in any interesting problem is usually very hard. In the present work, following the approach by Glazek and Maslowski in the flat space, we will study the exact renormalization of the same problem in a nontrivial geometric setting, namely in the two dimensional hyperbolic space. Delta function potential is an asymptotically free quantum mechanical problem which makes it resemble nonabelian gauge theories, yet it can be treated exactly in this nontrivial geometry.
Perturbative renormalization of the electric field correlator
Christensen, C
2016-01-01
The momentum diffusion coefficient of a heavy quark in a hot QCD plasma can be extracted as a transport coefficient related to the correlator of two colour-electric fields dressing a Polyakov loop. We determine the perturbative renormalization factor for a particular lattice discretization of this correlator within Wilson's SU(3) gauge theory, finding a ~12% NLO correction for values of the bare coupling used in the current generation of simulations. The impact of this result on existing lattice determinations is commented upon, and a possibility for non-perturbative renormalization through the gradient flow is pointed out.
Perturbative renormalization of the electric field correlator
Directory of Open Access Journals (Sweden)
C. Christensen
2016-04-01
Full Text Available The momentum diffusion coefficient of a heavy quark in a hot QCD plasma can be extracted as a transport coefficient related to the correlator of two colour-electric fields dressing a Polyakov loop. We determine the perturbative renormalization factor for a particular lattice discretization of this correlator within Wilson's SU(3 gauge theory, finding a ∼12% NLO correction for values of the bare coupling used in the current generation of simulations. The impact of this result on existing lattice determinations is commented upon, and a possibility for non-perturbative renormalization through the gradient flow is pointed out.
Perturbative renormalization of the electric field correlator
Christensen, C.; Laine, M.
2016-04-01
The momentum diffusion coefficient of a heavy quark in a hot QCD plasma can be extracted as a transport coefficient related to the correlator of two colour-electric fields dressing a Polyakov loop. We determine the perturbative renormalization factor for a particular lattice discretization of this correlator within Wilson's SU(3) gauge theory, finding a ∼ 12% NLO correction for values of the bare coupling used in the current generation of simulations. The impact of this result on existing lattice determinations is commented upon, and a possibility for non-perturbative renormalization through the gradient flow is pointed out.
Hypercuboidal renormalization in spin foam quantum gravity
Bahr, Benjamin; Steinhaus, Sebastian
2017-06-01
In this article, we apply background-independent renormalization group methods to spin foam quantum gravity. It is aimed at extending and elucidating the analysis of a companion paper, in which the existence of a fixed point in the truncated renormalization group flow for the model was reported. Here, we repeat the analysis with various modifications and find that both qualitative and quantitative features of the fixed point are robust in this setting. We also go into details about the various approximation schemes employed in the analysis.
Renormalized dissipation in plasmas with finite collisionality
Energy Technology Data Exchange (ETDEWEB)
Parker, S.E. [Princeton Plasma Physics Lab., NJ (United States); Carati, D. [Universite Libre de Bruxelles (Belgium). Service de Physique Statistique
1995-05-01
A nonlinear truncation procedure for Fourier-Hermite expansion of Boltzmann-type plasma equations is presented which eliminates fine velocity scale, taking into account its effect on coarser scales. The truncated system is then transformed back to (x, v) space which results in a renormalized Boltzmann equation. The resulting equation may allow for coarser velocity space resolution in kinetic simulations while reducing to the original Boltzmann equation when fine velocity scales are resolved. To illustrate the procedure, renormalized equations are derived for one dimensional electrostatic plasmas in which collisions are modeled by the Lenard-Bernstein operator.
Weidinger, Lukas; Bauer, Florian; von Delft, Jan
2017-01-01
We introduce an equilibrium formulation of the functional renormalization group (fRG) for inhomogeneous systems capable of dealing with spatially finite-ranged interactions. In the general third-order truncated form of fRG, the dependence of the two-particle vertex is described by O (N4) independent variables, where N is the dimension of the single-particle system. In a previous paper [Bauer et al., Phys. Rev. B 89, 045128 (2014), 10.1103/PhysRevB.89.045128], the so-called coupled-ladder approximation (CLA) was introduced and shown to admit a consistent treatment for models with a purely onsite interaction, reducing the vertex to O (N2) independent variables. In this work, we introduce an extended version of this scheme, called the extended coupled ladder approximation (eCLA), which includes a spatially extended feedback between the individual channels, measured by a feedback length L , using O (N2L2) independent variables for the vertex. We apply the eCLA in a static approximation and at zero temperature to three types of one-dimensional model systems, focusing on obtaining the linear response conductance. First, we study a model of a quantum point contact (QPC) with a parabolic barrier top and on-site interactions. In our setup, where the characteristic length lx of the QPC ranges between approximately 4-10 sites, eCLA achieves convergence once L becomes comparable to lx. It also turns out that the additional feedback stabilizes the fRG flow. This enables us, second, to study the geometric crossover between a QPC and a quantum dot, again for a one-dimensional model with on-site interactions. Third, the enlarged feedback also enables the treatment of a finite-ranged interaction extending over up to L sites. Using a simple estimate for the form of such a finite-ranged interaction in a QPC with a parabolic barrier top, we study its effects on the conductance and the density. We find that for low densities and sufficiently large interaction ranges the conductance
Childers, Annie Burns; Vidakovic, Draga
2014-01-01
This paper explores sixty-six students' personal meaning and interpretation of the vertex of a quadratic function in relation to their understanding of quadratic functions in two different representations, algebraic and word problem. Several categories emerged from students' personal meaning of the vertex including vertex as maximum or minimum…
Kim, Jun-Seok; Kang, Min-Hyeok; Jang, Jun-Hyeok; Oh, Jae-Seop
2015-01-01
[Purpose] This study examined the selective electromyographic activity of the lumbar paraspinal muscles in healthy male and female subjects in the prone trunk extension (PTE) and four-point kneeling arm and leg lift (FPKAL) exercises to determine the most beneficial exercise for selective activation of the lumbar multifidus (LM). [Subjects and Methods] Twenty healthy male and female subjects participated in this study. Surface electromyographic data were collected from the left-side lumbar er...
Enhancement of field renormalization in scalar theories via functional renormalization group
Zappalà, Dario
2012-01-01
The flow equations of the Functional Renormalization Group are applied to the O(N)-symmetric scalar theory, for N=1 and N=4, to determine the effective potential and the renormalization function of the field in the broken phase. The flow equations of these quantities are derived from a reduction of the full flow of the effective action onto a set of equations for the n-point vertices of the theory. In our numerical analysis, the infrared limit, corresponding to the vanishing of the running momentum scale in the equations, is approached to obtain the physical values of the parameters by extrapolation. In the N=4 theory a non-perturbatively large value of the physical renormalization of the longitudinal component of the field is observed. The dependence of the field renormalization on the UV cut-off and on the bare coupling is also investigated.
Bonini, M; Marchesini, G
1993-01-01
A new proof of perturbative renormalizability and infrared finiteness for a scalar massless theory is obtained from a formulation of renormalized field theory based on the Wilson renormalization group. The loop expansion of the renormalized Green functions is deduced from the Polchinski equation of renormalization group. The resulting Feynman graphs are organized in such a way that the loop momenta are ordered. It is then possible to analyse their ultraviolet and infrared behaviours by iterative methods. The necessary subtractions and the corresponding counterterms are automatically generated in the process of fixing the physical conditions for the ``relevant'' vertices at the normalization point. The proof of perturbative renormalizability and infrared finiteness is simply based on dimensional arguments and does not require the usual analysis of topological properties of Feynman graphs.
Bonini, M.; D'Attanasio, M.; Marchesini, G.
1993-11-01
A new proof of perturbative renormalizability and infrared finiteness for a scalar massless theory is obtained from a formulation of renormalized field theory based on the Wilson renormalization group. The loop expansion of the renormalized Green functions is deduced from the Polchinski equation of renormalization group. The resulting Feynman graphs are organized in such a way that the loop momenta are ordered. It is then possible to analyse their ultraviolet and infrared behaviours by iterative methods. The necessary subtractions and the corresponding counterterms are automatically generated in the process of fixing the physical conditions for the "relevant" vertices at the normalization point. The proof of perturbative renormalizability and infrared finiteness is simply based on dimensional arguments and does not require the usual analysis of topological properties of Feynman graphs.
Energy Technology Data Exchange (ETDEWEB)
Actis, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Passarino, G. [Torino Univ. (Italy). Dipt. di Fisica Teorica; INFN, Sezione di Torino (Italy)
2006-12-15
In part I and II of this series of papers all elements have been introduced to extend, to two loops, the set of renormalization procedures which are needed in describing the properties of a spontaneously broken gauge theory. In this paper, the final step is undertaken and finite renormalization is discussed. Two-loop renormalization equations are introduced and their solutions discussed within the context of the minimal standard model of fundamental interactions. These equations relate renormalized Lagrangian parameters (couplings and masses) to some input parameter set containing physical (pseudo-)observables. Complex poles for unstable gauge and Higgs bosons are used and a consistent setup is constructed for extending the predictivity of the theory from the Lep1 Z-boson scale (or the Lep2 WW scale) to regions of interest for LHC and ILC physics. (orig.)
VERTEX: manganese transport through oxygen minima
Martin, John H.; Knauer, George A.
1984-01-01
Manganese transport through a well-developed oxygen minimum was studied off central Mexico (18°N, 108°W) in October-November 1981 as part of the VERTEX (Vertical Transport and Exchange) research program. Refractory, leachable and dissolved Mn fractions associated with particulates caught in traps set at eight depths (120-1950 m) were analyzed. Particles entering the oxygen minimum had relatively large Mn loads; however, as the particulates sank further into the minimum, total Mn fluxes steadily decreased from 190 nmol m -2 day -1 at 120 m to 36 nmol m -2 day -1 at 400 m. Manganese fluxes then steadily increased in the remaining 800-1950 m, reaching rates of up to 230 nmol m -2 day -1 at 1950 m. Manganese concentrations were also measured in the water column. Dissolved Mn levels Rate-of-change estimates based on trap flux data yield regeneration rates of up to 0.44 nmol kg -1 yr -1 in the upper oxygen minimum (120-200 m). However, only 30% of the dissolved Mn in the oxygen minimum appears to be from sinking particulate regeneration; the other 70% probably results from continental-slope-release-horizontal-transport processes. Dissolved Mn scavenges back onto particles as oxygen levels begin to increase with depth. Scavenging rates ranging from -0.03 to -0.09 nmol kg -1 yr -1 were observed at depths from 700 to 1950 m. These scavenging rates result in Mn residence times of 16-19 years, and scavenging rate constants on the order of 0.057 yr -1. Manganese removal via scavenging on sinking particles below the oxygen minimum is balanced by Mn released along continental boundaries and transported horizontally via advective-diffusive processes. Manganese appears to be very weakly associated with particulates. Nevertheless, the amounts of Mn involved with sinking biogenic particles are large, and the resulting fluxes are on the same order of magnitude as those necessary to explain the excess Mn accumulating on the sea floor. The overall behavior of Mn observed in this, and
Composite operators in lattice QCD nonperturbative renormalization
Göckeler, M; Oelrich, H; Perlt, H; Petters, D; Rakow, P; Schäfer, A; Schierholz, G; Schiller, A
1999-01-01
We investigate the nonperturbative renormalization of composite operators in lattice QCD restricting ourselves to operators that are bilinear in the quark fields. These include operators which are relevant to the calculation of moments of hadronic structure functions. The computations are based on Monte Carlo simulations using quenched Wilson fermions.
Renormalization Group Equations for the CKM matrix
Kielanowski, P; Montes de Oca Y, J H
2008-01-01
We derive the one loop renormalization group equations for the Cabibbo-Kobayashi-Maskawa matrix for the Standard Model, its two Higgs extension and the minimal supersymmetric extension in a novel way. The derived equations depend only on a subset of the model parameters of the renormalization group equations for the quark Yukawa couplings so the CKM matrix evolution cannot fully test the renormalization group evolution of the quark Yukawa couplings. From the derived equations we obtain the invariant of the renormalization group evolution for three models which is the angle $\\alpha$ of the unitarity triangle. For the special case of the Standard Model and its extensions with $v_{1}\\approx v_{2}$ we demonstrate that also the shape of the unitarity triangle and the Buras-Wolfenstein parameters $\\bar{\\rho}=(1-{1/2}\\lambda^{2})\\rho$ and $\\bar{\\eta}=(1-{1/2}\\lambda^{2})\\eta$ are conserved. The invariance of the angles of the unitarity triangle means that it is not possible to find a model in which the CKM matrix mi...
Finite volume renormalization scheme for fermionic operators
Energy Technology Data Exchange (ETDEWEB)
Monahan, Christopher; Orginos, Kostas [JLAB
2013-11-01
We propose a new finite volume renormalization scheme. Our scheme is based on the Gradient Flow applied to both fermion and gauge fields and, much like the Schr\\"odinger functional method, allows for a nonperturbative determination of the scale dependence of operators using a step-scaling approach. We give some preliminary results for the pseudo-scalar density in the quenched approximation.
Basis Optimization Renormalization Group for Quantum Hamiltonian
Sugihara, Takanori
2001-01-01
We find an algorithm of numerical renormalization group for spin chain models. The essence of this algorithm is orthogonal transformation of basis states, which is useful for reducing the number of relevant basis states to create effective Hamiltonian. We define two types of rotations and combine them to create appropriate orthogonal transformation.
RENORMALIZED ENERGY WITH VORTICES PINNING EFFECT
Institute of Scientific and Technical Information of China (English)
Ding Shijin
2000-01-01
This paper is a continuation of the previous paper in the Journal of Partial Differential Equations [1]. We derive in this paper the renormalized energy to further determine the locations of vortices in some case for the variational problem related to the superconducting thin films having variable thickness.
A covariant representation of the Ball–Chiu vertex
Energy Technology Data Exchange (ETDEWEB)
Ahmadiniaz, Naser, E-mail: naser@ifm.umich.mx [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Apdo. Postal 2-82, C.P. 58040, Morelia, Michoacán (Mexico); Dipartimento di Fisica, Università di Bologna and INFN, Sezione di Bologna, Via Irnerio 46, I-40126 Bologna (Italy); Schubert, Christian, E-mail: schubert@ifm.umich.mx [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Apdo. Postal 2-82, C.P. 58040, Morelia, Michoacán (Mexico); Dipartimento di Fisica, Università di Bologna and INFN, Sezione di Bologna, Via Irnerio 46, I-40126 Bologna (Italy); Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Mühlenberg 1, D-14476 Potsdam (Germany)
2013-04-21
In nonabelian gauge theory the three-gluon vertex function contains important structural information, in particular on infrared divergences, and is also an essential ingredient in the Schwinger–Dyson equations. Much effort has gone into analyzing its general structure, and at the one-loop level also a number of explicit computations have been done, using various approaches. Here we use the string-inspired formalism to unify the calculations of the scalar, spinor and gluon loop contributions to the one-loop vertex, leading to an extremely compact representation in all cases. The vertex is computed fully off-shell and in dimensionally continued form, so that it can be used as a building block for higher-loop calculations. We find that the Bern–Kosower loop replacement rules, originally derived for the on-shell case, hold off-shell as well. We explain the relation of the structure of this representation to the low-energy effective action, and establish the precise connection with the standard Ball–Chiu decomposition of the vertex. This allows us also to predict that the vanishing of the completely antisymmetric coefficient function S of this decomposition is not a one-loop accident, but persists at higher-loop orders. The sum rule found by Binger and Brodsky, which leads to the vanishing of the one-loop vertex in N=4 SYM theory, in the present approach relates to worldline supersymmetry.
Directed Subset Feedback Vertex Set is Fixed-Parameter Tractable
Chitnis, Rajesh; Hajiaghayi, MohammadTaghi; Marx, Dániel
2012-01-01
Given a graph $G$ and an integer $k$, the \\textsc{Feedback Vertex Set} (\\textsc{FVS}) problem asks if there is a vertex set $T$ of size at most $k$ that hits all cycles in the graph. Bodlaender (WG '91) gave the first fixed-parameter algorithm for \\textsc{FVS} in undirected graphs. The fixed-parameter tractability status of \\textsc{FVS} in directed graphs was a long-standing open problem until Chen et al. (STOC '08) showed that it is fixed-parameter tractable by giving an $4^{k}k!n^{O(1)}$ algorithm. In the subset versions of this problems, we are given an additional subset $S$ of vertices (resp. edges) and we want to hit all cycles passing through a vertex of $S$ (resp. an edge of $S$). Indeed both the edge and vertex versions are known to be equivalent in the parameterized sense. Recently the \\textsc{Subset Feedback Vertex Set} in undirected graphs was shown to be FPT by Cygan et al. (ICALP '11) and Kakimura et al. (SODA '12). We generalize the result of Chen et al. (STOC '08) by showing that \\textsc{Subset...
Hessian and graviton propagator of the proper vertex
Shirazi, Atousa Chaharsough; Vilensky, Ilya
2015-01-01
The proper spin-foam vertex amplitude is obtained from the EPRL vertex by projecting out all but a single gravitational sector, in order to achieve correct semi-classical behavior. In this paper we calculate the gravitational two-point function predicted by the proper spin-foam vertex to lowest order in the vertex expansion. We find the same answer as in the EPRL case in the `continuum spectrum' limit, so that the theory is consistent with the predictions of linearized gravity in the regime of small curvature. The method for calculating the two-point function is similar to that used in prior works: we cast it in terms of an action integral and to use stationary phase methods. Thus, the calculation of the Hessian matrix plays a key role. Once the Hessian is calculated, it is used not only to calculate the two-point function, but also to calculate the coefficient appearing in the semi-classical limit of the proper vertex amplitude itself. This coefficient is the effective discrete "measure factor" encoded in th...
On trees with total domination number equal to edge-vertex domination number plus one
Indian Academy of Sciences (India)
B Krishnakumari; Y B Venkatakrishnan; Marcin Krzywkowski
2016-05-01
An edge $e \\in E(G)$ dominates a vertex $v \\in V(G)$ if $e$ is incident with $v$ or $e$ is incident with a vertex adjacent to $v$. An edge-vertex dominating set of a graph $G$ is a set $D$ of edges of $G$ such that every vertex of $G$ is edge-vertex dominated by an edge of $D$. The edge-vertex domination number of a graph $G$ is the minimum cardinality of an edge-vertex dominating set of $G$. A subset $D \\subseteq V(G)$ is a total dominating set of $G$ if every vertex of $G$ has a neighbor in $D$. The total domination number of $G$ is the minimum cardinality of a total dominating set of $G$. We characterize all trees with total domination number equal to edge-vertex domination number plus one.
Renormalization and effective actions for general relativity
Energy Technology Data Exchange (ETDEWEB)
Neugebohrn, F.
2007-05-15
Quantum gravity is analyzed from the viewpoint of the renormalization group. The analysis is based on methods introduced by J. Polchinski concerning the perturbative renormalization with flow equations. In the first part of this work, the program of renormalization with flow equations is reviewed and then extended to effective field theories that have a finite UV cutoff. This is done for a scalar field theory by imposing additional renormalization conditions for some of the nonrenormalizable couplings. It turns out that one so obtains a statement on the predictivity of the effective theory at scales far below the UV cutoff. In particular, nonrenormalizable theories can be treated without problems in the proposed framework. In the second part, the standard covariant BRS quantization program for Euclidean Einstein gravity is applied. A momentum cutoff regularization is imposed and the resulting violation of the Slavnov-Taylor identities is discussed. Deriving Polchinski's renormalization group equation for Euclidean quantum gravity, the predictivity of effective quantum gravity at scales far below the Planck scale is investigated with flow equations. A fine-tuning procedure for restoring the violated Slavnov-Taylor identities is proposed and it is argued that in the effective quantum gravity context, the restoration will only be accomplished with finite accuracy. Finally, the no-cutoff limit of Euclidean quantum gravity is analyzed from the viewpoint of the Polchinski method. It is speculated whether a limit with nonvanishing gravitational constant might exist where the latter would ultimatively be determined by the cosmological constant and the masses of the elementary particles. (orig.)
On the uniqueness of d-vertex magic constant
Directory of Open Access Journals (Sweden)
Arumugam S.
2014-05-01
Full Text Available Let G = (V,E be a graph of order n and let D ⊆ {0, 1, 2, 3, . . .}. For v ∈ V, let ND(v = {u ∈ V : d(u, v ∈ D}. The graph G is said to be D-vertex magic if there exists a bijection f : V (G → {1, 2, . . . , n} such that for all v ∈ V, ∑uv∈ND(v f(u is a constant, called D-vertex magic constant. O’Neal and Slater have proved the uniqueness of the D-vertex magic constant by showing that it can be determined by the D-neighborhood fractional domination number of the graph. In this paper we give a simple and elegant proof of this result. Using this result, we investigate the existence of distance magic labelings of complete r-partite graphs where r ≥ 4.
Plethystic Vertex Operators and Boson-Fermion Correspondences
Fauser, Bertfried; King, Ronald C
2016-01-01
We study the algebraic properties of plethystic vertex operators, introduced in J. Phys. A: Math. Theor. 43 405202 (2010), underlying the structure of symmetric functions associated with certain generalized universal character rings of subgroups of the general linear group, defined to stabilize tensors of Young symmetry type characterized by a partition of arbitrary shape \\pi. Here we establish an extension of the well-known boson-fermion correspondence involving Schur functions and their associated (Bernstein) vertex operators: for each \\pi, the modes generated by the plethystic vertex operators and their suitably constructed duals, satisfy the anticommutation relations of a complex Clifford algebra. The combinatorial manipulations underlying the results involve exchange identities exploiting the Hopf-algebraic structure of certain symmetric function series and their plethysms.
Plethystic vertex operators and boson-fermion correspondences
Fauser, Bertfried; Jarvis, Peter D.; King, Ronald C.
2016-10-01
We study the algebraic properties of plethystic vertex operators, introduced in (2010 J. Phys. A: Math. Theor. 43 405202), underlying the structure of symmetric functions associated with certain generalized universal character rings of subgroups of the general linear group, defined to stabilize tensors of Young symmetry type characterized by a partition of arbitrary shape π. Here we establish an extension of the well-known boson-fermion correspondence involving Schur functions and their associated (Bernstein) vertex operators: for each π, the modes generated by the plethystic vertex operators and their suitably constructed duals, satisfy the anticommutation relations of a complex Clifford algebra. The combinatorial manipulations underlying the results involve exchange identities exploiting the Hopf-algebraic structure of certain symmetric function series and their plethysms.
Fatigue crack shape prediction based on vertex singularity
Directory of Open Access Journals (Sweden)
Hutař P.
2008-11-01
Full Text Available Due to the existence of vertex singularity at the point where the crack intersects the free surface, stress distribution around the crack tip and the type of the singularity is changed. In the interior of the specimen the classical singular behaviour of the crack is dominant and can be described using analytic equations. Contrary to this, at the free surface or in the boundary layer close to free surface the vertex singularity is significant. The influence of vertex singularity on crack behaviour and a crack shape for a three-dimensional structure is described in this paper. The results presented make it possible to estimate fatigue crack growth rate and crack shape using the concept of the generalized stress intensity factor. The estimated fatigue crack shape can help to provide a more reliable estimation of the fatigue life of the structures considered.
Vertex-centred Method to Detect Communities in Evolving Networks
Canu, Maël; d'Allonnes, Adrien Revault
2016-01-01
Finding communities in evolving networks is a difficult task and raises issues different from the classic static detection case. We introduce an approach based on the recent vertex-centred paradigm. The proposed algorithm, named DynLOCNeSs, detects communities by scanning and evaluating each vertex neighbourhood, which can be done independently in a parallel way. It is done by means of a preference measure, using these preferences to handle community changes. We also introduce a new vertex neighbourhood preference measure, CWCN, more efficient than current existing ones in the considered context. Experimental results show the relevance of this measure and the ability of the proposed approach to detect classical community evolution patterns such as grow-shrink and merge-split.
Semiclassical correlation functions of Wilson loops and local vertex operators
Hernandez, Rafael
2012-01-01
We analyze correlation functions of Wilson loop observables and local vertex operators within the strong-coupling regime of the AdS/CFT correspondence. When the local operator corresponds to a light string state with finite conserved charges the correlation function can be evaluated in the semiclassical approximation of large string tension, where the contribution from the light vertex can be neglected. We consider the cases where the Wilson loops are described by two concentric surfaces and the local vertices are the superconformal chiral primary scalar or a singlet massive scalar operator.
Simulations of silicon vertex tracker for star experiment at RHIC
Energy Technology Data Exchange (ETDEWEB)
Odyniec, G.; Cebra, D.; Christie, W.; Naudet, C.; Schroeder, L.; Wilson, W. [Lawrence Berkeley Lab., CA (United States); Liko, D. [Institut fur Hochenenergiephysik, Vienna, (Austria); Cramer, J.; Prindle, D.; Trainor, T. [Univ. of Washington, Seattle (United States); Braithwaite, W. [Univ. of Arkansas, Little Rock (United States)
1991-12-31
The first computer simulations to optimize the Silicon Vertex Tracker (SVT) designed for the STAR experiment at RHIC are presented. The physics goals and the expected complexity of the events at RHIC dictate the design of a tracking system for the STAR experiment. The proposed tracking system will consist of a silicon vertex tracker (SVT) to locate the primary interaction and secondary decay vertices and to improve the momentum resolution, and a time projection chamber (TPC), positioned inside a solenoidal magnet, for continuous tracking.
The RAVE/VERTIGO vertex reconstruction toolkit and framework
Waltenberger, W.; Mitaroff, W.; Moser, F.; Pflugfelder, B.; Riedel, H. V.
2008-07-01
A detector-independent toolkit for vertex reconstruction (RAVE1) is being developed, along with a standalone framework (VERTIGO2) for testing, analyzing and debugging. The core algorithms represent state-of-the-art for geometric vertex finding and fitting by both linear (Kalman filter) and robust estimation methods. Main design goals are ease of use, flexibility for embedding into existing software frameworks, extensibility, and openness. The implementation is based on modern object-oriented techniques, is coded in C++ with interfaces for Java and Python, and follows an open-source approach. A beta release is available.
RAVE-a Detector-independent vertex reconstruction toolkit
Energy Technology Data Exchange (ETDEWEB)
Waltenberger, Wolfgang [Institute of High Energy Physics, Austrian Academy of Sciences A-1050 Vienna (Austria)], E-mail: walten@hephy.oeaw.ac.at; Mitaroff, Winfried; Moser, Fabian [Institute of High Energy Physics, Austrian Academy of Sciences A-1050 Vienna (Austria)
2007-10-21
A detector-independent toolkit for vertex reconstruction (RAVE) is being developed, along with a standalone framework (VERTIGO) for testing, analyzing and debugging. The core algorithms represent state of the art for geometric vertex finding and fitting by both linear (Kalman filter) and robust estimation methods. Main design goals are ease of use, flexibility for embedding into existing software frameworks, extensibility, and openness. The implementation is based on modern object-oriented techniques, is coded in C++ with interfaces for Java and Python, and follows an open-source approach. A beta release is available.
The RAVE/VERTIGO vertex reconstruction toolkit and framework
Energy Technology Data Exchange (ETDEWEB)
Waltenberger, W; Mitaroff, W; Moser, F; Pflugfelder, B; Riedel, H V [Austrian Academy of Sciences, Institute of High Energy Physics, A-1050 Vienna (Austria)], E-mail: walten@hephy.oeaw.ac.at
2008-07-15
A detector-independent toolkit for vertex reconstruction (RAVE{sup 1}) is being developed, along with a standalone framework (VERTIGO{sup 2}) for testing, analyzing and debugging. The core algorithms represent state-of-the-art for geometric vertex finding and fitting by both linear (Kalman filter) and robust estimation methods. Main design goals are ease of use, flexibility for embedding into existing software frameworks, extensibility, and openness. The implementation is based on modern object-oriented techniques, is coded in C++ with interfaces for Java and Python, and follows an open-source approach. A beta release is available.
Simulations with the PANDA micro-vertex-detector
Energy Technology Data Exchange (ETDEWEB)
Kliemt, Ralf
2013-07-17
The PANDA experiment will be built at the upcoming FAIR facility at GSI in Darmstadt, featuring antiproton-proton reactions hadron physics in a medium energy range. Charm physics will play an important role and therefore secondary decays relatively close to the interaction zone as well. The MVD will be the detector closest to these and will provide high-quality vertex position measurements. Alongside the detector layout and hardware development a detailed detector simulation and reconstruction software is required. This work contains the detailed description and the performance studies of the software developed for the MVD. Furthermore, vertexing tools are introduced and their performance is studied for the MVD.
Simulations of silicon vertex tracker for star experiment at RHIC
Energy Technology Data Exchange (ETDEWEB)
Odyniec, G.; Cebra, D.; Christie, W.; Naudet, C.; Schroeder, L.; Wilson, W. [Lawrence Berkeley Lab., CA (United States); Liko, D. [Institut fur Hochenenergiephysik, Vienna, (Austria); Cramer, J.; Prindle, D.; Trainor, T. [Univ. of Washington, Seattle (United States); Braithwaite, W. [Univ. of Arkansas, Little Rock (United States)
1991-12-31
The first computer simulations to optimize the Silicon Vertex Tracker (SVT) designed for the STAR experiment at RHIC are presented. The physics goals and the expected complexity of the events at RHIC dictate the design of a tracking system for the STAR experiment. The proposed tracking system will consist of a silicon vertex tracker (SVT) to locate the primary interaction and secondary decay vertices and to improve the momentum resolution, and a time projection chamber (TPC), positioned inside a solenoidal magnet, for continuous tracking.
On vertex-coloring 13-edge-weighting
Institute of Scientific and Technical Information of China (English)
Tao WANG; Qinglin YU
2008-01-01
L. Addario-Berry et al. [Discrete Appl. Math., 2008, 156:1168-1174] have shown that there exists a 16-edge-weighting such that the induced vertex coloring is proper. In this note, we improve their result and prove that there exists a 13-edge-weighting of a graph G, such that itsinduced vertex coloring of G is proper. This result is one step close to the original conjecture posed by M. Karofiski et al. [J. Combin. Theory, Set. B, 2004, 91: 151-157].
Preliminary studies for the LHCb vertex detector vacuum system
Doets, M; Van Bakel, N; Van den Brand, J F J; van den Brand, Jo
2000-01-01
We lay down some general considerations which will serve as a starting point for design studies of a realistic LHCb vertex detector vacuum system. Based on these considerations, we propose a design strategy and identify issues to be further studied. In particular we try to outline some boundary conditions imposed by LHC and LHCb on the vacuum system. We discuss two possibilities for the LHCb vertex detector vacuum system. The preferred strategy uses a differentially pumped vacuum system with the silicon detectors separated from the beam line vacuum. Some estimations on static vacuum pressures and gas flows are presented.
The Virasoro vertex algebra and factorization algebras on Riemann surfaces
Williams, Brian
2017-08-01
This paper focuses on the connection of holomorphic two-dimensional factorization algebras and vertex algebras which has been made precise in the forthcoming book of Costello-Gwilliam. We provide a construction of the Virasoro vertex algebra starting from a local Lie algebra on the complex plane. Moreover, we discuss an extension of this factorization algebra to a factorization algebra on the category of Riemann surfaces. The factorization homology of this factorization algebra is computed as the correlation functions. We provide an example of how the Virasoro factorization algebra implements conformal symmetry of the beta-gamma system using the method of effective BV quantization.
Dannheim, D
2014-01-01
A detector concept based on hybrid planar pixel-detector technology is under development for the CLIC vertex detector. It comprises fast, low-power and small-pitch readout ASICs implemented in 65 nm CMOS technology (CLICpix) coupled to ultra-thin sensors via low-mass interconnects. The power dissipation of the readout chips is reduced by means of power pulsing, allowing for a cooling system based on forced gas flow. In this paper the CLIC vertex-detector requirements are reviewed and the current status of R&D on sensors, readout and detector integration is presented.
Dannheim, D
2014-01-01
A detector concept based on hybrid pixel-detector technology is under development for the CLIC vertex detector. It comprises fast, low-power and small-pitch readout ASICs implemented in 65 nm CMOS technology (CLICpix) coupled to ultra-thin sensors (planar or active HV-CMOS) via low-mass interconnects. The power dissipation of the readout chips is reduced by means of power pulsing, allowing for a cooling system based on forced air flow. In this contribution the CLIC vertex-detector requirements are reviewed and the current status of R&D on readout and sensors is presented.
The VELO (VErtex LOcator) at the LHCb experiment
De Capua, S.
2008-01-01
The LHCb silicon vertex locator (VELO) is an array of silicon planes installed in a retractable roman pot system, which will enable the LHCb experiment to reconstruct and trigger on b-hadrons produced in collisions at the LHC. The VELO will be also used to attempt measuring the absolute luminosity with a novel method based on vertex reconstruction of beam gas interactions. In this paper the VELO system, its construction and the results from the commissioning phase are presented. The options for a possible upgraded detector are also discussed.
Winstanley, Julie B; Saw, Robyn; Boyle, Frances; Thompson, John
2013-02-01
The FACT-Melanoma (FACT-M) is one of only two validated quality-of-life instruments designed specifically for use in patients with melanoma. The instrument incorporates FACT-G, followed by a set of questionnaire items that are specific to melanoma; all items are scored on a five-point response scale. The primary aim of this study was to evaluate the five-point response format of the FACT-M for goodness of fit to the Rasch measurement model, and to investigate whether rescoring the instrument using a four-point response format improved the psychometric properties. Two data sets of similar patient sample sizes (n=127 and 123) were used to test the reliability and validity of the generic instrument (FACT-G) to measure quality of life for patients with melanoma. The Additional Concerns and Melanoma Surgery subscales were subjected to a more detailed analysis using a combination of confirmatory factor analysis and Rasch analysis techniques. The Rasch model fit of the FACT-M was improved by the use of a four-point response format, together with the deletion of three items. Principal components analysis suggested that two melanoma-specific subscales existed within the Additional Concerns subscale and each could be reduced to seven items, respectively, with improved goodness of fit to the Rasch model. The FACT-M instrument showed improved fit to the Rasch model specifications when the items adopted a four-point response format. These results point to possible improvements in the content and structure of the FACT-M for use in future melanoma clinical trials. However, further study should be conducted with larger samples, selected by disease and treatment status.
Mizuno, Y; Ohi, K; Sogabe, T; Yamamoto, Y; Kaneda, Y
2010-09-01
A numerical analysis is made on the four-point correlation function in a similarity range of a model of two-dimensional passive scalar field ψ advected by a turbulent velocity field with infinitely small correlation time. The model yields an exact closure equation for the four-point correlation Ψ{4} of ψ, which may be casted into the form of an eigenvalue problem in the similarity range. The analysis of the eigenvalue problem gives not only the scale dependence of Ψ{4} , but also the dependence on the configuration of the four points. The numerical analysis gives S4(R)∝R{ζ{4}} in the similarity range in which S2(R)∝R{ζ{2}} , where S_{N} is the structure function defined by S{N}(R)≡⟨[ψ(x+R)-ψ(x)]{N} and ζ{4}≠2ζ{2} . The estimate of ζ_{4} by the numerical analysis of the eigenvalue problem is in good agreement with numerical simulations so far reported. The agreement supports the idea of universality of the exponent ζ{4} in the sense that ζ_{4} is insensitive to conditions of ψ outside the similarity range. The numerical analysis also shows that the correlation C(R,r)≡[ψ(x+R)-ψ(x)]{2}[ψ(x+r)-ψ(x)]{2}> is stronger than that given by the joint-normal approximation, and scales like C(R,r)∝(r/R){χ} for r/R<1 with R and r in the similarity range, where χ is a constant depending on the angle between R and r .
Kashima, Yohei
2012-01-01
For the Hubbard model on the two-dimensional copper-oxide lattice, equal-time four-point correlation functions at positive temperature are proved to decay exponentially in the thermodynamic limit if the magnitude of the on-site interactions is smaller than some power of temperature. This result especially implies that the equal-time correlation functions for singlet Cooper pairs of various symmetries decay exponentially in the distance between the Cooper pairs in high temperatures or in low-temperature weak-coupling regimes. The proof is based on a multi-scale integration over the Matsubara frequency.
Oberle, L. G.; Fralick, G. C.
1986-01-01
A series of FORTRAN-77 programs is described which correct for the effect of a conducting substrate when a linear four-point probe is used to measure the resistivity of a thin film. The resistivity of the film is given in terms of the thicknesses of the film and substrate, the known resistivity of the substrate, and the measured delta V/I. A full development is given as well as a complete description of the operation of the programs. The programs themselves can be obtained through COSMIC, and are identified as LEW No. 14381.
Krupych, Oleg; Savaryn, Viktoriya; Vlokh, Rostyslav
2014-04-01
A recently proposed technique representing a combination of digital imaging laser interferometry with a classical four-point bending method is applied to a canonical nonlinear optical crystal, LiNbO₃, to precisely determine a full matrix of its piezo-optic coefficients (POCs). The contribution of a secondary piezo-optic effect to the POCs is investigated experimentally and analyzed theoretically. Based on the POCs thus obtained, a full matrix of strain-optic coefficients (SOCs) is calculated and the appropriate errors are estimated. A comparison of our experimental errors for the POCs and SOCs with the known reference data allows us to claim the present technique as the most precise.
Renormalization of Magnetic Excitations in Praseodymium
DEFF Research Database (Denmark)
Lindgård, Per-Anker
1975-01-01
The magnetic exciton renormalization and soft-mode behaviour as the temperature approaches zero of the singlet-doublet magnet (dhcp)pr are accounted for by a selfconsistent rpa theory with no adjustable parameters. The crystal-field splitting between the ground state and the doublet is d=3.74 mev...... and the ratio between the exchange interaction and d is very close to unity. However, zero-point motion prevents the system from ordering.......The magnetic exciton renormalization and soft-mode behaviour as the temperature approaches zero of the singlet-doublet magnet (dhcp)pr are accounted for by a selfconsistent rpa theory with no adjustable parameters. The crystal-field splitting between the ground state and the doublet is d=3.74 mev...
Lectures on renormalization and asymptotic safety
Nagy, Sandor
2012-01-01
A short introduction is given on the functional renormalization group method, putting emphasis on its nonperturbative aspects. The method enables to find nontrivial fixed points in quantum field theoretic models which make them free from divergences and leads to the concept of asymptotic safety. It can be considered as a generalization of the asymptotic freedom which plays a key role in the perturbative renormalization. We summarize and give a short discussion of some important models, which are asymptotically safe such as the Gross-Neveu model, the nonlinear $\\sigma$ model, the sine-Gordon model, and the model of quantum Einstein gravity. We also give a detailed analysis of infrared behavior of the models where a spontaneous symmetry breaking takes place. The deep infrared behavior of the broken phase cannot be treated within the framework of perturbative calculations. We demonstrate that there exists an infrared fixed point in the broken phase which creates a new scaling regime there, however its structure ...
Information loss along the renormalization flow
Energy Technology Data Exchange (ETDEWEB)
Beny, Cedric; Osborne, Tobias [Leibniz Universitaet Hannover (Germany)
2013-07-01
Our ability to probe the real world is always limited by experimental constraints such as the precision of our instruments. It is remarkable that the resulting imperfect data nevertheless contains regularities which can be understood in terms of effective laws. The renormalization group (RG) aims to formalize the relationship between effective theories summarizing the behaviour of a single system probed at different length scales. An important feature of the RG is its tendency to converge to few universal effective field theories at large scale. We explicitly model the change of resolution at which a quantum lattice system is probed as a completely positive semigroup on density operators, i.e., a family of quantum channels, and derive from it a renormalization ''group'' on effective theories. This formalism suggests a family of finite distinguishability metrics which contract under the RG, hence identifying the information that is lost on the way to universal RG fixed points.
Poissonian renormalizations, exponentials, and power laws
Eliazar, Iddo
2013-05-01
This paper presents a comprehensive “renormalization study” of Poisson processes governed by exponential and power-law intensities. These Poisson processes are of fundamental importance, as they constitute the very bedrock of the universal extreme-value laws of Gumbel, Fréchet, and Weibull. Applying the method of Poissonian renormalization we analyze the emergence of these Poisson processes, unveil their intrinsic dynamical structures, determine their domains of attraction, and characterize their structural phase transitions. These structural phase transitions are shown to be governed by uniform and harmonic intensities, to have universal domains of attraction, to uniquely display intrinsic invariance, and to be intimately connected to “white noise” and to “1/f noise.” Thus, we establish a Poissonian explanation to the omnipresence of white and 1/f noises.
Holographic renormalization and the electroweak precision parameters
Round, Mark
2010-09-01
We study the effects of holographic renormalization on an AdS/QCD inspired description of dynamical electroweak symmetry breaking. Our model is a 5D slice of AdS5 geometry containing a bulk scalar and SU(2)×SU(2) gauge fields. The scalar field obtains a vacuum expectation value (VEV) which represents a condensate that triggers electroweak symmetry breaking. Fermion fields are constrained to live on the UV brane and do not propagate in the bulk. The two-point functions are holographically renormalized through the addition of boundary counterterms. Measurable quantities are then expressed in terms of well-defined physical parameters, free from any spurious dependence on the UV cutoff. A complete study of the precision parameters is carried out and bounds on physical quantities derived. The large-N scaling of results is discussed.
ENCORE: An extended contractor renormalization algorithm.
Albuquerque, A Fabricio; Katzgraber, Helmut G; Troyer, Matthias
2009-04-01
Contractor renormalization (CORE) is a real-space renormalization-group method to derive effective Hamiltionians for microscopic models. The original CORE method is based on a real-space decomposition of the lattice into small blocks and the effective degrees of freedom on the lattice are tensor products of those on the small blocks. We present an extension of the CORE method that overcomes this restriction. Our generalization allows the application of CORE to derive arbitrary effective models whose Hilbert space is not just a tensor product of local degrees of freedom. The method is especially well suited to search for microscopic models to emulate low-energy exotic models and can guide the design of quantum devices.
Poissonian renormalizations, exponentials, and power laws.
Eliazar, Iddo
2013-05-01
This paper presents a comprehensive "renormalization study" of Poisson processes governed by exponential and power-law intensities. These Poisson processes are of fundamental importance, as they constitute the very bedrock of the universal extreme-value laws of Gumbel, Fréchet, and Weibull. Applying the method of Poissonian renormalization we analyze the emergence of these Poisson processes, unveil their intrinsic dynamical structures, determine their domains of attraction, and characterize their structural phase transitions. These structural phase transitions are shown to be governed by uniform and harmonic intensities, to have universal domains of attraction, to uniquely display intrinsic invariance, and to be intimately connected to "white noise" and to "1/f noise." Thus, we establish a Poissonian explanation to the omnipresence of white and 1/f noises.
Accurate renormalization group analyses in neutrino sector
Energy Technology Data Exchange (ETDEWEB)
Haba, Naoyuki [Graduate School of Science and Engineering, Shimane University, Matsue 690-8504 (Japan); Kaneta, Kunio [Kavli IPMU (WPI), The University of Tokyo, Kashiwa, Chiba 277-8568 (Japan); Takahashi, Ryo [Graduate School of Science and Engineering, Shimane University, Matsue 690-8504 (Japan); Yamaguchi, Yuya [Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan)
2014-08-15
We investigate accurate renormalization group analyses in neutrino sector between ν-oscillation and seesaw energy scales. We consider decoupling effects of top quark and Higgs boson on the renormalization group equations of light neutrino mass matrix. Since the decoupling effects are given in the standard model scale and independent of high energy physics, our method can basically apply to any models beyond the standard model. We find that the decoupling effects of Higgs boson are negligible, while those of top quark are not. Particularly, the decoupling effects of top quark affect neutrino mass eigenvalues, which are important for analyzing predictions such as mass squared differences and neutrinoless double beta decay in an underlying theory existing at high energy scale.
Disordered Holographic Systems I: Functional Renormalization
Adams, Allan
2011-01-01
We study quenched disorder in strongly correlated systems via holography, focusing on the thermodynamic effects of mild electric disorder. Disorder is introduced through a random potential which is assumed to self-average on macroscopic scales. Studying the flow of this distribution with energy scale leads us to develop a holographic functional renormalization scheme. We test this scheme by computing thermodynamic quantities and confirming that the Harris criterion for relevance, irrelevance or marginality of quenched disorder holds.
Renormalization group for non-relativistic fermions.
Shankar, R
2011-07-13
A brief introduction is given to the renormalization group for non-relativistic fermions at finite density. It is shown that Landau's theory of the Fermi liquid arises as a fixed point (with the Landau parameters as marginal couplings) and its instabilities as relevant perturbations. Applications to related areas, nuclear matter, quark matter and quantum dots, are briefly discussed. The focus will be on explaining the main ideas to people in related fields, rather than addressing the experts.
Renormalized versions of the massless Thirring model
Casana, R
2003-01-01
We present a non-perturbative study of the (1+1)-dimensional massless Thirring model by using path integral methods. The model presents two features, one of them has a local gauge symmetry that is implemented at quantum level and the other one without this symmetry. We make a detailed analysis of their UV divergence structure, a non-perturbative regularization and renormalization processes are proposed.
Dense nucleonic matter and the renormalization group
Drews, Matthias; Klein, Bertram; Weise, Wolfram
2013-01-01
Fluctuations are included in a chiral nucleon-meson model within the framework of the functional renormalization group. The model, with parameters fitted to reproduce the nuclear liquid-gas phase transition, is used to study the phase diagram of QCD. We find good agreement with results from chiral effective field theory. Moreover, the results show a separation of the chemical freeze-out line and chiral symmetry restoration at large baryon chemical potentials.
Dense nucleonic matter and the renormalization group
Directory of Open Access Journals (Sweden)
Drews Matthias
2014-03-01
Full Text Available Fluctuations are included in a chiral nucleon-meson model within the framework of the functional renormalization group. The model, with parameters fitted to reproduce the nuclear liquid-gas phase transition, is used to study the phase diagram of QCD. We find good agreement with results from chiral effective field theory. Moreover, the results show a separation of the chemical freeze-out line and chiral symmetry restoration at large baryon chemical potentials.
Field renormalization in photonic crystal waveguides
DEFF Research Database (Denmark)
Colman, Pierre
2015-01-01
A novel strategy is introduced in order to include variations of the nonlinearity in the nonlinear Schro¨dinger equation. This technique, which relies on renormalization, is in particular well adapted to nanostructured optical systems where the nonlinearity exhibits large variations up to two...... Schro¨dinger equation is an occasion for physics-oriented considerations and unveils the potential of photonic crystal waveguides for the study of new nonlinear propagation phenomena....
Renormalization of QCD under longitudinal rescaling
Xiao, Jing
2009-01-01
The form of the quantum Yang-Mills action, under a longitudinal rescaling is determined using a Wilsonian renormalization group. The high-energy limit, is the extreme limit of such a rescaling. We compute the anomalous dimensions and discuss the validity of the high-energy limit. This thesis is an expanded version of joint work with P. Orland, which appeared in arXiv:0901.2955.
A Hopf algebra deformation approach to renormalization
Ionescu, L M; Ionescu, Lucian M.; Marsalli, Michael
2003-01-01
We investigate the relation between Connes-Kreimer Hopf algebra approach to renomalization and deformation quantization. Both approaches rely on factorization, the correspondence being established at the level of Wiener-Hopf algebras, and double Lie algebras/Lie bialgebras, via r-matrices. It is suggested that the QFTs obtained via deformation quantization and renormalization correspond to each other in the sense of Kontsevich/Cattaneo-Felder.
Zero Point Energy of Renormalized Wilson Loops
Hidaka, Yoshimasa; Pisarski, Robert D.
2009-01-01
The quark antiquark potential, and its associated zero point energy, can be extracted from lattice measurements of the Wilson loop. We discuss a unique prescription to renormalize the Wilson loop, for which the perturbative contribution to the zero point energy vanishes identically. A zero point energy can arise nonperturbatively, which we illustrate by considering effective string models. The nonperturbative contribution to the zero point energy vanishes in the Nambu model, but is nonzero wh...
Quark confinement and the renormalization group.
Ogilvie, Michael C
2011-07-13
Recent approaches to quark confinement are reviewed, with an emphasis on their connection to renormalization group (RG) methods. Basic concepts related to confinement are introduced: the string tension, Wilson loops and Polyakov lines, string breaking, string tension scaling laws, centre symmetry breaking and the deconfinement transition at non-zero temperature. Current topics discussed include confinement on R(3)×S(1), the real-space RG, the functional RG and the Schwinger-Dyson equation approach to confinement.
Renormalization group and linear integral equations
Klein, W.
1983-04-01
We develop a position-space renormalization-group transformation which can be employed to study general linear integral equations. In this Brief Report we employ our method to study one class of such equations pertinent to the equilibrium properties of fluids. The results of applying our method are in excellent agreement with known numerical calculations where they can be compared. We also obtain information about the singular behavior of this type of equation which could not be obtained numerically.
Integrable Renormalization II: the general case
Ebrahimi-Fard, K; Kreimer, D; Ebrahimi-Fard, Kurusch; Guo, Li; Kreimer, Dirk
2004-01-01
We extend the results we obtained in an earlier work. The cocommutative case of rooted ladder trees is generalized to a full Hopf algebra of (decorated) rooted trees. For Hopf algebra characters with target space of Rota-Baxter type, the Birkhoff decomposition of renormalization theory is derived by using the Rota-Baxter double construction, respectively Atkinson's theorem. We also outline the extension to the Hopf algebra of Feynman graphs via decorated rooted trees.
Renormalization persistency of tensor force in nuclei
Tsunoda, Naofumi; Tsukiyama, Koshiroh; Hjorth-Jensen, Morten
2011-01-01
In this work we analyze the tensor-force component of effective interactions appropriate for nuclear shell-model studies, with particular emphasis on the monopole term of the interactions. Standard nucleon-nucleon ($NN$) interactions such as AV8' and $\\chi$N$^3$LO are tailored to shell-model studies by employing $V_{low k}$ techniques to handle the short-range repulsion of the $NN$ interactions and by applying many-body perturbation theory to incorporate in-medium effects. We show, via numerical studies of effective interactions for the $sd$ and $pf$ shells, that the tensor-force contribution to the monopole term of the effective interaction is barely changed by these renormalization procedures, resulting in almost the same monopole term as the one of the bare $NN$ interactions. We propose to call this feature {\\it Renormalization Persistency} of the tensor force, as it is a remarkable property of the renormalization and should have many interesting consequences in nuclear systems. For higher multipole terms,...
A shape dynamical approach to holographic renormalization
Energy Technology Data Exchange (ETDEWEB)
Gomes, Henrique [University of California at Davis, Davis, CA (United States); Gryb, Sean [Utrecht University, Institute for Theoretical Physics, Utrecht (Netherlands); Radboud University Nijmegen, Institute for Mathematics, Astrophysics and Particle Physics, Nijmegen (Netherlands); Koslowski, Tim [University of New Brunswick, Fredericton, NB (Canada); Mercati, Flavio; Smolin, Lee [Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada)
2015-01-01
We provide a bottom-up argument to derive some known results from holographic renormalization using the classical bulk-bulk equivalence of General Relativity and Shape Dynamics, a theory with spatial conformal (Weyl) invariance. The purpose of this paper is twofold: (1) to advertise the simple classical mechanism, trading off gauge symmetries, that underlies the bulk-bulk equivalence of General Relativity and Shape Dynamics to readers interested in dualities of the type of AdS/conformal field theory (CFT); and (2) to highlight that this mechanism can be used to explain certain results of holographic renormalization, providing an alternative to the AdS/CFT conjecture for these cases. To make contact with the usual semiclassical AdS/CFT correspondence, we provide, in addition, a heuristic argument that makes it plausible that the classical equivalence between General Relativity and Shape Dynamics turns into a duality between radial evolution in gravity and the renormalization group flow of a CFT. We believe that Shape Dynamics provides a new perspective on gravity by giving conformal structure a primary role within the theory. It is hoped that this work provides the first steps toward understanding what this new perspective may be able to teach us about holographic dualities. (orig.)
Holographic entanglement renormalization of topological insulators
Wen, Xueda; Cho, Gil Young; Lopes, Pedro L. S.; Gu, Yingfei; Qi, Xiao-Liang; Ryu, Shinsei
2016-08-01
We study the real-space entanglement renormalization group flows of topological band insulators in (2+1) dimensions by using the continuum multiscale entanglement renormalization ansatz (cMERA). Given the ground state of a Chern insulator, we construct and study its cMERA by paying attention, in particular, to how the bulk holographic geometry and the Berry curvature depend on the topological properties of the ground state. It is found that each state defined at different energy scale of cMERA carries a nonzero Berry flux, which is emanated from the UV layer of cMERA, and flows towards the IR. Hence, a topologically nontrivial UV state flows under the renormalization group to an IR state, which is also topologically nontrivial. On the other hand, we found that there is an obstruction to construct the exact ground state of a topological insulator with a topologically trivial IR state. That is, if we try to construct a cMERA for the ground state of a Chern insulator by taking a topologically trivial IR state, the resulting cMERA does not faithfully reproduce the exact ground state at all length scales.
Face aftereffects involve local repulsion, not renormalization.
Storrs, Katherine R; Arnold, Derek H
2015-01-01
After looking at a photograph of someone for a protracted period (adaptation), a previously neutral-looking face can take on an opposite appearance in terms of gender, identity, and other attributes-but what happens to the appearance of other faces? Face aftereffects have repeatedly been ascribed to perceptual renormalization. Renormalization predicts that the adapting face and more extreme versions of it should appear more neutral after adaptation (e.g., if the adaptor was male, it and hyper-masculine faces should look more feminine). Other aftereffects, such as tilt and spatial frequency, are locally repulsive, exaggerating differences between adapting and test stimuli. This predicts that the adapting face should be little changed in appearance after adaptation, while more extreme versions of it should look even more extreme (e.g., if the adaptor was male, it should look unchanged, while hyper-masculine faces should look even more masculine). Existing reports do not provide clear evidence for either pattern. We overcame this by using a spatial comparison task to measure the appearance of stimuli presented in differently adapted retinal locations. In behaviorally matched experiments we compared aftereffect patterns after adapting to tilt, facial identity, and facial gender. In all three experiments data matched the predictions of a locally repulsive, but not a renormalizing, aftereffect. These data are consistent with the existence of similar encoding strategies for tilt, facial identity, and facial gender.
Renormalization group flows and continual Lie algebras
Bakas, Ioannis
2003-01-01
We study the renormalization group flows of two-dimensional metrics in sigma models and demonstrate that they provide a continual analogue of the Toda field equations based on the infinite dimensional algebra G(d/dt;1). The resulting Toda field equation is a non-linear generalization of the heat equation, which is integrable in target space and shares the same dissipative properties in time. We provide the general solution of the renormalization group flows in terms of free fields, via Backlund transformations, and present some simple examples that illustrate the validity of their formal power series expansion in terms of algebraic data. We study in detail the sausage model that arises as geometric deformation of the O(3) sigma model, and give a new interpretation to its ultra-violet limit by gluing together two copies of Witten's two-dimensional black hole in the asymptotic region. We also provide some new solutions that describe the renormalization group flow of negatively curved spaces in different patches...
Renormalization, Hopf algebras and Mellin transforms
Panzer, Erik
2014-01-01
This article aims to give a short introduction into Hopf-algebraic aspects of renormalization, enjoying growing attention for more than a decade by now. As most available literature is concerned with the minimal subtraction scheme, we like to point out properties of the kinematic subtraction scheme which is also widely used in physics (under the names of MOM or BPHZ). In particular we relate renormalized Feynman rules $\\phi_R$ in this scheme to the universal property of the Hopf algebra $H_R$ of rooted trees, exhibiting a refined renormalization group equation which is equivalent to $\\phi_R: H_R \\rightarrow K[x]$ being a morphism of Hopf algebras to the polynomials in one indeterminate. Upon introduction of analytic regularization this results in efficient combinatorial recursions to calculate $\\phi_R$ in terms of the Mellin transform. We find that different Feynman rules are related by a distinguished class of Hopf algebra automorphisms of $H_R$ that arise naturally from Hochschild cohomology. Also we recall...
Chiral symmetry breaking with the Curtis-Pennington vertex
Atkinson, D.; Gusynin, V. P.; Maris, P.
1992-01-01
Published in: Phys. Lett. B 303 (1993) 157-162 citations recorded in [Science Citation Index] Abstract: We study chiral symmetry breaking in quenched QED$_4$, using a vertex Ansatz recently proposed by Curtis and Pennington. Bifurcation analysis is employed to establish the existence of a critical c
Track and vertex finding performance with the CMS inner tracker
Caner, A; Khanov, A I; Stepanov, N
1999-01-01
The Compact Muon Solenoid (CMS) Tracker Collaboration has recently finalised the design of the tracking detector. After characterising the detector layout, we review in detail the algorithms developed for track and vertex reconstruction. We discuss the reconstruction capability for several benchmark event topologies and assess the projected performance of the CMS tracking detector. (12 refs).
Approximation Algorithms for Edge Partitioned Vertex Cover Problems
Bera, Suman Kalyan; Kumar, Amit; Roy, Sambuddha
2011-01-01
In the Partial Vertex Cover (PVC) problem we are given an undirected graph G = (V, E), a positive cost associated with each vertex and a positive integer k and the goal is to find a minimum cost subset of vertices S such that atleast k edges of the graph are covered. In this paper we consider two new generalization of the PVC problem. In the first variation which we call Partition Vertex Cover (Partition-VC) problem, the edges of the graph G are divided into n disjoint partitions $P_1, P_2... P_n$ and we have to select a minimum cost subset of vertices S such that atleast $k_i$ edges are covered from partition $P_i$. In the second variation which we call Knapsack Partition Vertex Cover (KPVC) problem, in addition to the previous conditions, each edge e has a profit $\\pi_{e}$ associated with it and we have an added knapsack constraint that the total profit of the covered edges in partition $P_i$ should be atleast $\\Pi_i$. We give an $O(log n)$ approximation for both the problems using a combination of determin...
One vertex spin-foams with the Dipole Cosmology boundary
Kisielowski, Marcin; Puchta, Jacek
2012-01-01
We find all the spin-foams contributing in the first order of the vertex expansion to the transition amplitude of the Bianchi-Rovelli-Vidotto Dipole Cosmology model. Our algorithm is general and provides spin-foams of arbitrarily given, fixed: boundary and, respectively, a number of internal vertices. We use the recently introduced Operator Spin-Network Diagrams framework.
A cohomology theory of grading-restricted vertex algebras
Huang, Yi-Zhi
2010-01-01
We introduce a cohomology theory of grading-restricted vertex algebras. To construct the "correct" cohomologies, we consider linear maps from tensor powers of a grading-restricted vertex algebra to "rational functions valued in the algebraic completion of a module for the algebra," instead of linear maps from tensor powers of the algebra to a module for the algebra. One subtle complication arising from such "rational functions valued in the algebraic completion of a module" is that we have to carefully address the issue of convergence when we compose these linear maps with vertex operators. In particular, for each $n\\in \\N$, we have an inverse system $\\{H^{n}_{m}(V, W)\\}_{m\\in \\Z_{+}}$ of $n$-th cohomologies and an additional $n$-th cohomology $H_{\\infty}^{n}(V, W)$ of a grading-restricted vertex algebra $V$ with coefficients in a $V$-module $W$ such that $H_{\\infty}^{n}(V, W)$ is isomorphic to the inverse limit of the inverse system $\\{H^{n}_{m}(V, W)\\}_{m\\in \\Z_{+}}$. In the case of $n=2$, there is an addit...
A Remark on Newest Vertex Bisection in Any Space Dimension
D. Gallistl; M. Schedensack; R.P. Stevenson
2014-01-01
With newest vertex bisection, there is no uniform bound on the number of n-simplices that need to be refined to arrive at the smallest conforming refinement T′ of a conforming partition T in which one simplex has been bisected. In this note, we show that the difference in levels between any T′∈T′ an
Vertex deviation maps to bracked the Milky Way resonant radius
Roca-Fàbrega, S.; Antoja, T.; Figueras, F.; Valenzuela, O.; Romero-Gómez, M.; Pichardo, B.
2015-05-01
We map the kinematics of stars in simulated galaxy disks with spiral arms using the velocity ellipsoid vertex deviation (l_v). We use test particle simulations, and for the first time, fully self-consistent high resolution N-body models. We compare our maps with the Tight Winding Approximation model analytical predictions. We see that for all barred models spiral arms rotate closely to a rigid body manner and the vertex deviation values correlate with the density peaks position bounded by overdense and underdense regions. In such cases, vertex deviation sign changes from negative to positive when crossing the spiral arms in the direction of disk rotation, in regions where the spiral arms are in between corotation (CR) and the Outer Lindblad Resonance (OLR). By contrast, when the arm sections are inside the CR and outside the OLR, l_v changes from negative to positive.We propose that measurements of the vertex deviations pattern can be used to trace the position of the main resonances of the spiral arms. We propose that this technique might exploit future data from Gaia and APOGEE surveys. For unbarred N-body simulations with spiral arms corotating with disk material at all radii, our analysis suggests that no clear correlation exists between l_v and density structures.
Random matrices and the six-vertex model
Bleher, Pavel
2013-01-01
This book provides a detailed description of the Riemann-Hilbert approach (RH approach) to the asymptotic analysis of both continuous and discrete orthogonal polynomials, and applications to random matrix models as well as to the six-vertex model. The RH approach was an important ingredient in the proofs of universality in unitary matrix models. This book gives an introduction to the unitary matrix models and discusses bulk and edge universality. The six-vertex model is an exactly solvable two-dimensional model in statistical physics, and thanks to the Izergin-Korepin formula for the model with domain wall boundary conditions, its partition function matches that of a unitary matrix model with nonpolynomial interaction. The authors introduce in this book the six-vertex model and include a proof of the Izergin-Korepin formula. Using the RH approach, they explicitly calculate the leading and subleading terms in the thermodynamic asymptotic behavior of the partition function of the six-vertex model with domain wa...
A Vertex Oriented Approach to Minimum Cost Spanning Tree Problems
Ciftci, B.B.; Tijs, S.H.
2007-01-01
In this paper we consider spanning tree problems, where n players want to be connected to a source as cheap as possible. We introduce and analyze (n!) vertex oriented construct and charge procedures for such spanning tree situations leading in n steps to a minimum cost spanning tree and a cost shari
Self-locking degree-4 vertex origami structures
Fang, Hongbin; Li, Suyi; Wang, K. W.
2016-11-01
A generic degree-4 vertex (4-vertex) origami possesses one continuous degree-of-freedom for rigid folding, and this folding process can be stopped when two of its facets bind together. Such facet-binding will induce self-locking so that the overall structure stays at a pre-specified configuration without additional locking elements or actuators. Self-locking offers many promising properties, such as programmable deformation ranges and piecewise stiffness jumps, that could significantly advance many adaptive structural systems. However, despite its excellent potential, the origami self-locking features have not been well studied, understood, and used. To advance the state of the art, this research conducts a comprehensive investigation on the principles of achieving and harnessing self-locking in 4-vertex origami structures. Especially, for the first time, this study expands the 4-vertex structure construction from single-component to dual-component designs and investigates their self-locking behaviours. By exploiting various tessellation designs, this research discovers that the dual-component designs offer the origami structures with extraordinary attributes that the single-component structures do not have, which include the existence of flat-folded locking planes, programmable locking points and deformability. Finally, proof-of-concept experiments investigate how self-locking can effectively induce piecewise stiffness jumps. The results of this research provide new scientific knowledge and a systematic framework for the design, analysis and utilization of self-locking origami structures for many potential engineering applications.
The role of geometry in 4-vertex origami mechanics
Waitukaitis, Scott; Dieleman, Peter; van Hecke, Martin
Origami offers an interesting design platform metamaterials because it strongly couples mechanics with geometry. Even so, most research carried out so far has been limited to one or two particular patterns. I will discuss the full geometrical space of the most common origami building block, the 4-vertex, and show how exotic geometries can have dramatic effects on the mechanics.
Redford, S
2015-01-01
The Compact Linear Collider is a candidate to be the next high-energy particle physics collider. Using a novel acceleration technique, electrons and positrons would be brought into collision with a centre-of-mass energy of up to 3 TeV. Despite challenging levels of beam-induced background, this would provide a relatively clean environment in which to perform precision physics measurements. The vertex detector would be crucial in achieving this, and would need to provide accurate particle tracking information to facilitate secondary vertex reconstruction and jet flavour-tagging. With this goal in mind, current technological limits are being stretched to design a low occupancy, low mass and low-power dissipation vertex detector for CLIC. A concept comprising thin hybrid pixel detectors coupled to high- performance readout ASICs, power-pulsing and air-flow cooling is under development. In this paper, the CLIC vertex detector requirements are reviewed and the current status of R&D on sensors, readout, powerin...
Two-loop and n-loop eikonal vertex corrections
Kidonakis, Nikolaos
2003-01-01
I present calculations of two-loop vertex corrections with massive and massless partons in the eikonal approximation. I show that the $n$-loop result for the UV poles can be given in terms of the one-loop calculation.
Anomalous $\\omega$-$Z$-$\\gamma$ Vertex from Hidden Local Symmetry
Harada, Masayasu; Yamawaki, Koichi
2011-01-01
We formulate the general form of omega-Z-gamma vertex in the framework based on the hidden local symmetry (HLS), which arises from the gauge invariant terms for intrinsic parity-odd (IP-odd) part of the effective action. Those terms are given as the homogeneous part of the general solution (having free parameters) to the Wess-Zumino (WZ) anomaly equation and hence are not determined by the anomaly, in sharp contrast to the Harvey-Hill-Hill (HHH) action where the relevant vertex is claimed to be uniquely determined by the anomaly. We show that, even in the framework that HHH was based on, the omega-Z-gamma vertex is actually not determined by the anomaly but by the homogeneous (anomaly-free) part of the general solution to the WZ anomaly equation having free parameters in the same way as in the HLS formulation: The HHH action is just a particular choice of the free parameters in the general solution. We further show that the omega-Z-gamma vertex related to the neutrino (nu) - nucleon (N) scattering cross secti...
W. K. H. Panofsky Prize Talk: The Silicon Vertex Trigger
Ristori, Luciano
2009-05-01
I will discuss the importance of real-time selection of events at a hadron collider, the ideas that led to the conception of the Silicon Vertex Trigger (SVT) and some historical notes on its construction and commissioning. I will also highlight some remarkable results obtained by CDF with the data selected by the SVT.
A Vertex Oriented Approach to Minimum Cost Spanning Tree Problems
Ciftci, B.B.; Tijs, S.H.
2007-01-01
In this paper we consider spanning tree problems, where n players want to be connected to a source as cheap as possible. We introduce and analyze (n!) vertex oriented construct and charge procedures for such spanning tree situations leading in n steps to a minimum cost spanning tree and a cost shari
Institute of Scientific and Technical Information of China (English)
高玮; 谢宜臣
2001-01-01
设计一个新的近代物理实验题目.利用阳极氧化法对半导体材料逐次去层，采用四探针法测量其每层的电阻率及相应杂质浓度，可得出半导体材料的杂质分布N(x).实验设备简单，测量方便，结果准确.并提供了自制四探针测量仪的方法.%A new topic in modern physics experiment is designed. Semiconductor material is removed layer by layer with anode oxidation method. Resistivity and relevant impurity concentration in every layer is measured with four point probe method. The impurity distribution of semiconductor material N(x)is obtained. The experiment equipment is simple, measurement is convenient, and result is accurate. The method to make four point probe instrument is provided.
Renormalization of multiple infinities and the renormalization group in string loops
Russo, J.; Tseytlin, A. A.
1990-08-01
There is a widespread belief that string loop massles divergences may be absorbed into a renormalization of σ-model couplings (space-time metric and dilaton). The crucial property for this idea to be consistently implemented to arbitrary order in string loops should be the renormalizability of the generating functional for string amplitudes. We make several non-trivial checks of the renormalizability by explicit calculations at genus 1, 2 and 3. The renormalizability becomes non-trivial at the log 2ɛ order. We show that the log 2 ɛ counterterms are universal (e.g. the same counterterms provide finiteness both of two-loop scattering amplitudes and of the three-loop partition function) and are related to the log ɛ counterterms (β-functions) in the standard way dictated by the renormalization group. This checks the consistency of the Fischler-Susskind mechanism and implies that the renormalization group acts properly at the string loop level.
Hilbert space renormalization for the many-electron problem
Li, Zhendong
2015-01-01
Renormalization is a powerful concept in the many-body problem. Inspired by the highly successful density matrix renormalization group (DMRG) algorithm, and the quantum chemical graphical representation of configuration space, we introduce a new theoretical tool: Hilbert space renormalization, to describe many-electron correlations. While in DMRG, the many-body states in nested Fock subspaces are successively renormalized, in Hilbert space renormalization, many-body states in nested Hilbert subspaces undergo renormalization. This provides a new way to classify and combine configurations. The underlying wavefunction ansatz, namely the Hilbert space matrix product state (HS-MPS), has a very rich and flexible mathematical structure. It provides low-rank tensor approximations to any configuration interaction (CI) space through restricting either the 'physical indices' or the coupling rules in the HS-MPS. Alternatively, simply truncating the 'virtual dimension' of the HS-MPS leads to a family of size-extensive wav...
Gauge and Scheme Dependence of Mixing Matrix Renormalization
Pilaftsis, Apostolos
2002-01-01
We revisit the issue of mixing matrix renormalization in theories that include Dirac or Majorana fermions. We show how a gauge-variant on-shell renormalized mixing matrix can be related to a manifestly gauge-independent one within a generalized ${\\bar {\\rm MS}}$ scheme of renormalization. This scheme-dependent relation is a consequence of the fact that in any scheme of renormalization, the gauge-dependent part of the mixing-matrix counterterm is ultra-violet safe and has a pure dispersive form. Employing the unitarity properties of the theory, we can successfully utilize the afore-mentioned scheme-dependent relation to preserve basic global or local symmetries of the bare Lagrangian through the entire process of renormalization. As an immediate application of our study, we derive the gauge-independent renormalization-group equations of mixing matrices in a minimal extension of the Standard Model with isosinglet neutrinos.
Proposed proper Engle-Pereira-Rovelli-Livine vertex amplitude
Engle, Jonathan
2013-04-01
As established in a prior work of the author, the linear simplicity constraints used in the construction of the so-called “new” spin-foam models mix three of the five sectors of Plebanski theory as well as two dynamical orientations, and this is the reason for multiple terms in the asymptotics of the Engle-Pereira-Rovelli-Livine vertex amplitude as calculated by Barrett et al. Specifically, the term equal to the usual exponential of i times the Regge action corresponds to configurations either in sector (II+) with positive orientation or sector (II-) with negative orientation. The presence of the other terms beyond this cause problems in the semiclassical limit of the spin-foam model when considering multiple 4-simplices due to the fact that the different terms for different 4-simplices mix in the semiclassical limit, leading in general to a non-Regge action and hence non-Regge and nongravitational configurations persisting in the semiclassical limit. To correct this problem, we propose to modify the vertex so its asymptotics include only the one term of the form eiSRegge. To do this, an explicit classical discrete condition is derived that isolates the desired gravitational sector corresponding to this one term. This condition is quantized and used to modify the vertex amplitude, yielding what we call the “proper Engle-Pereira-Rovelli-Livine vertex amplitude.” This vertex still depends only on standard SU(2) spin-network data on the boundary, is SU(2) gauge-invariant, and is linear in the boundary state, as required. In addition, the asymptotics now consist in the single desired term of the form eiSRegge, and all degenerate configurations are exponentially suppressed. A natural generalization to the Lorentzian signature is also presented.
Domination parameters of a graph with added vertex
Directory of Open Access Journals (Sweden)
Maciej Zwierzchowski
2004-01-01
Full Text Available Let \\(G=(V,E\\ be a graph. A subset \\(D\\subseteq V\\ is a total dominating set of \\(G\\ if for every vertex \\(y\\in V\\ there is a vertex \\(x\\in D\\ with \\(xy\\in E\\. A subset \\(D\\subseteq V\\ is a strong dominating set of \\(G\\ if for every vertex \\(y\\in V-D\\ there is a vertex \\(x\\in D\\ with \\(xy\\in E\\ and \\(\\deg _{G}(x\\geq\\deg _{G}(y\\. The total domination number \\(\\gamma _{t}(G\\ (the strong domination number \\(\\gamma_{S}(G\\ is defined as the minimum cardinality of a total dominating set (a strong dominating set of \\(G\\. The concept of total domination was first defined by Cockayne, Dawes and Hedetniemi in 1980 [Cockayne E. J., Dawes R. M., Hedetniemi S. T.: Total domination in graphs. Networks 10 (1980, 211–219], while the strong domination was introduced by Sampathkumar and Pushpa Latha in 1996 [Pushpa Latha L., Sampathkumar E.: Strong weak domination and domination balance in a graph. Discrete Mathematics 161 (1996, 235–242]. By a subdivision of an edge \\(uv\\in E\\ we mean removing edge \\(uv\\, adding a new vertex \\(x\\, and adding edges \\(ux\\ and \\(vx\\. A graph obtained from \\(G\\ by subdivision an edge \\(uv\\in E\\ is denoted by \\(G\\oplus u_{x}v_{x}\\. The behaviour of the total domination number and the strong domination number of a graph \\(G\\oplus u_{x}v_{x}\\ is developed.
Limit theorems for vertex-reinforced jump processes on regular trees
Collevecchio, Andrea
2009-01-01
Consider a vertex-reinforced jump process defined on a regular tree, where each vertex has exactly $b$ children, with $b \\ge 3$. We prove the strong law of large numbers and the central limit theorem for the distance of the process from the root. Notice that it is still unknown if vertex-reinforced jump process is transient on the binary tree.
A quantum hybrid with a thin antenna at the vertex of a wedge
Carlone, Raffaele; Posilicano, Andrea
2017-03-01
We study the spectrum, resonances and scattering matrix of a quantum Hamiltonian on a "hybrid surface" consisting of a half-line attached by its endpoint to the vertex of a concave planar wedge. At the boundary of the wedge, outside the vertex, homogeneous Dirichlet conditions are imposed. The system is tunable by varying the measure of the angle at the vertex.
Renormalization in general theories with inter-generation mixing
Energy Technology Data Exchange (ETDEWEB)
Kniehl, Bernd A. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Sirlin, Alberto [New York Univ., NY (United States). Dept. of Physics
2011-11-15
We derive general and explicit expressions for the unrenormalized and renormalized dressed propagators of fermions in parity-nonconserving theories with inter-generation mixing. The mass eigenvalues, the corresponding mass counterterms, and the effect of inter-generation mixing on their determination are discussed. Invoking the Aoki-Hioki-Kawabe-Konuma-Muta renormalization conditions and employing a number of very useful relations from Matrix Algebra, we show explicitly that the renormalized dressed propagators satisfy important physical properties. (orig.)
An algebraic Birkhoff decomposition for the continuous renormalization group
Girelli, F; Martinetti, P
2004-01-01
This paper aims at presenting the first steps towards a formulation of the Exact Renormalization Group Equation in the Hopf algebra setting of Connes and Kreimer. It mostly deals with some algebraic preliminaries allowing to formulate perturbative renormalization within the theory of differential equations. The relation between renormalization, formulated as a change of boundary condition for a differential equation, and an algebraic Birkhoff decomposition for rooted trees is explicited.
Enhancement of field renormalization in scalar theories via functional renormalization group
Zappalà, Dario
2012-01-01
The flow equations of the Functional Renormalization Group are applied to the O(N)-symmetric scalar theory, for N=1 and N=4, in four Euclidean dimensions, d=4, to determine the effective potential and the renormalization function of the field in the broken phase. In our numerical analysis, the infrared limit, corresponding to the vanishing of the running momentum scale in the equations, is approached to obtain the physical values of the parameters by extrapolation. In the N=4 theory a non-per...
Summation of Higher Order Effects using the Renormalization Group Equation
Elias, V; Sherry, T N
2004-01-01
The renormalization group (RG) is known to provide information about radiative corrections beyond the order in perturbation theory to which one has calculated explicitly. We first demonstrate the effect of the renormalization scheme used on these higher order effects determined by the RG. Particular attention is payed to the relationship between bare and renormalized quantities. Application of the method of characteristics to the RG equation to determine higher order effects is discussed, and is used to examine the free energy in thermal field theory, the relationship between the bare and renormalized coupling and the effective potential in massless scalar electrodynamics.
Applications of noncovariant gauges in the algebraic renormalization procedure
Boresch, A; Schweda, Manfred
1998-01-01
This volume is a natural continuation of the book Algebraic Renormalization, Perturbative Renormalization, Symmetries and Anomalies, by O Piguet and S P Sorella, with the aim of applying the algebraic renormalization procedure to gauge field models quantized in nonstandard gauges. The main ingredient of the algebraic renormalization program is the quantum action principle, which allows one to control in a unique manner the breaking of a symmetry induced by a noninvariant subtraction scheme. In particular, the volume studies in-depth the following quantized gauge field models: QED, Yang-Mills t
One Loop Renormalization of the Littlest Higgs Model
Grinstein, Benjamin; Uttayarat, Patipan
2011-01-01
In Little Higgs models a collective symmetry prevents the Higgs from acquiring a quadratically divergent mass at one loop. This collective symmetry is broken by weakly gauged interactions. Terms, like Yukawa couplings, that display collective symmetry in the bare Lagrangian are generically renormalized into a sum of terms that do not respect the collective symmetry except possibly at one renormalization point where the couplings are related so that the symmetry is restored. We study here the one loop renormalization of a prototypical example, the Littlest Higgs Model. Some features of the renormalization of this model are novel, unfamiliar form similar chiral Lagrangian studies.
Gauge and Scheme Dependence of Mixing Matrix Renormalization
Pilaftsis, Apostolos
2002-01-01
We revisit the issue of mixing matrix renormalization in theories that include Dirac or Majorana fermions. We show how a gauge-variant on-shell renormalized mixing matrix can be related to a manifestly gauge-independent one within a generalized ${\\bar {\\rm MS}}$ scheme of renormalization. This scheme-dependent relation is a consequence of the fact that in any scheme of renormalization, the gauge-dependent part of the mixing-matrix counterterm is ultra-violet safe and has a pure dispersive for...
Charm and Beauty Production from Secondary Vertexing at HERA
Energy Technology Data Exchange (ETDEWEB)
Thompson, Paul [University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom)
2010-07-01
Measurement of the Charm and Beauty Structure Functions using the H1 Vertex Detector at HERA Inclusive charm and beauty cross sections are measured in e{sup -} p and e{sup +}p neutral current collisions at HERA in the kinematic region of photon virtuality 5 < Q{sup 2} < 2000 GeV{sup 2} and Bjorken scaling variable 0.0002 < x < 0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb{sup -1}. The numbers of charm and beauty events are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions. Measurement of Charm and Beauty Jets in Deep Inelastic Scattering at HERA Measurements of the charm and beauty jet cross sections have been made in deep inelastic scattering at HERA for the kinematic region of photon virtuality Q{sup 2} > 6 GeV{sup 2} and elasticity variable 0.07 < y < 0.625 for jets in the laboratory frame with transverse energy E{sub T}{sup jet} > 6 GeV and pseudorapidity -1.0 < {eta}{sup jet} < 1.5. Measurements are also made requiring a jet in the Breit frame with E{sub T}{sup jet} > 6 GeV. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb{sup -1}. The number of charm and beauty jets are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are compared with QCD predictions and with previous measurements obtained using muon tagging. Charm and beauty production in deep inelastic scattering from inclusive secondary vertexing at ZEUS Charm and beauty production in deep inelastic scattering has been measured with the ZEUS detector using the full HERA II data set. The charm and beauty contents
Kim, Jun-Seok; Kang, Min-Hyeok; Jang, Jun-Hyeok; Oh, Jae-Seop
2015-04-01
[Purpose] This study examined the selective electromyographic activity of the lumbar paraspinal muscles in healthy male and female subjects in the prone trunk extension (PTE) and four-point kneeling arm and leg lift (FPKAL) exercises to determine the most beneficial exercise for selective activation of the lumbar multifidus (LM). [Subjects and Methods] Twenty healthy male and female subjects participated in this study. Surface electromyographic data were collected from the left-side lumbar erector spinae (LES) and LM muscles during PTE and FPKAL exercises. [Results] The LM/LES ratio related to selective activation of the lumbar paraspinal muscles during the FPKAL exercise was higher than that during PTE. [Conclusion] FPKAL exercise is safe and effective for the selective activation of the LM muscle.
Kanagawa, Taizo; Hobara, Rei; Matsuda, Iwao; Tanikawa, Takehiro; Natori, Akiko; Hasegawa, Shuji
2003-07-18
We have devised a "square micro-four-point probe method" using an independently driven ultrahigh-vacuum four-tip scanning tunneling microscope, and succeeded for the first time to directly measure anisotropic electrical conductance of a single-atomic layer on a solid surface. A quasi-one-dimensional metal of a single-domain Si(111)4 x 1-In had a surface-state conductance along the metallic atom chains (sigma(axially)) to be 7.2(+/-0.6) x 10(-4) S/square at room temperature, which was larger than that in the perpendicular direction (sigma(radially)) by approximately 60 times. The sigma(axially) was consistently interpreted by a Boltzmann equation with the anisotropic surface-state band dispersion, while the sigma(radially) was dominated by a surface-space-charge-layer conductance.
Lee, Seung-Yong; Kim, Gil-Sung; Lee, Mi-Ri; Lim, Hyuneui; Kim, Wan-Doo; Lee, Sang-Kwon
2013-05-10
We have successfully investigated the thermal conductivity (κ) of single-crystalline bismuth nanowires (BiNWs) with [110] growth direction, via a straightforward and powerful four-point-probe 3-ω technique in the temperature range 10-280 K. The BiNWs, which are well known as the most effective material for thermoelectric (TE) device applications, were synthesized by compressive thermal stress on a SiO2/Si substrate at 250-270 °C for 10 h. To understand the thermal transport mechanism of BiNWs, we present three kinds of experimental technique as follows, (i) a manipulation of a single BiNW by an Omni-probe in a focused ion beam (FIB), (ii) a suspended bridge structure integrating a four-point-probe chip by micro-fabrication to minimize the thermal loss to the substrate, and (iii) a simple 3-ω technique system setup. We found that the thermal transport of BiNWs is highly affected by boundary scattering of both phonons and electrons as the dominant heat carriers. The thermal conductivity of a single BiNW (d ~ 123 nm) was estimated to be ~2.9 W m(-1) K(-1) at 280 K, implying lower values compared to the thermal conductivity of the bulk (~11 W m(-1) K(-1) at 280 K). It was noted that this reduction in the thermal conductivity of the BiNWs could be due to strongly enhanced phonon-boundary scattering at the surface of the BiNWs. Furthermore, we present temperature-dependent (10-280 K) thermal conductivity of the BiNWs using the 3-ω technique.
Miccoli, I; Edler, F; Pfnür, H; Tegenkamp, C
2015-06-10
The electrical conductivity of solid-state matter is a fundamental physical property and can be precisely derived from the resistance measured via the four-point probe technique excluding contributions from parasitic contact resistances. Over time, this method has become an interdisciplinary characterization tool in materials science, semiconductor industries, geology, physics, etc, and is employed for both fundamental and application-driven research. However, the correct derivation of the conductivity is a demanding task which faces several difficulties, e.g. the homogeneity of the sample or the isotropy of the phases. In addition, these sample-specific characteristics are intimately related to technical constraints such as the probe geometry and size of the sample. In particular, the latter is of importance for nanostructures which can now be probed technically on very small length scales. On the occasion of the 100th anniversary of the four-point probe technique, introduced by Frank Wenner, in this review we revisit and discuss various correction factors which are mandatory for an accurate derivation of the resistivity from the measured resistance. Among others, sample thickness, dimensionality, anisotropy, and the relative size and geometry of the sample with respect to the contact assembly are considered. We are also able to derive the correction factors for 2D anisotropic systems on circular finite areas with variable probe spacings. All these aspects are illustrated by state-of-the-art experiments carried out using a four-tip STM/SEM system. We are aware that this review article can only cover some of the most important topics. Regarding further aspects, e.g. technical realizations, the influence of inhomogeneities or different transport regimes, etc, we refer to other review articles in this field.
Miccoli, I.; Edler, F.; Pfnür, H.; Tegenkamp, C.
2015-06-01
The electrical conductivity of solid-state matter is a fundamental physical property and can be precisely derived from the resistance measured via the four-point probe technique excluding contributions from parasitic contact resistances. Over time, this method has become an interdisciplinary characterization tool in materials science, semiconductor industries, geology, physics, etc, and is employed for both fundamental and application-driven research. However, the correct derivation of the conductivity is a demanding task which faces several difficulties, e.g. the homogeneity of the sample or the isotropy of the phases. In addition, these sample-specific characteristics are intimately related to technical constraints such as the probe geometry and size of the sample. In particular, the latter is of importance for nanostructures which can now be probed technically on very small length scales. On the occasion of the 100th anniversary of the four-point probe technique, introduced by Frank Wenner, in this review we revisit and discuss various correction factors which are mandatory for an accurate derivation of the resistivity from the measured resistance. Among others, sample thickness, dimensionality, anisotropy, and the relative size and geometry of the sample with respect to the contact assembly are considered. We are also able to derive the correction factors for 2D anisotropic systems on circular finite areas with variable probe spacings. All these aspects are illustrated by state-of-the-art experiments carried out using a four-tip STM/SEM system. We are aware that this review article can only cover some of the most important topics. Regarding further aspects, e.g. technical realizations, the influence of inhomogeneities or different transport regimes, etc, we refer to other review articles in this field.
Parameter Vertex Color Pada Animation Procedural 3D Model Vegetasi Musaceae
Directory of Open Access Journals (Sweden)
I Gede Ngurah Arya Indrayasa
2017-02-01
Full Text Available Penggunaan vegetasi untuk industri film, video game, simulasi, dan arsitektur visualisas merupakan faktor penting untuk menghasilkan adegan pemandangan alam lebih hidup. Penelitian ini bertujuan untuk mengetahui pengaruh dari vertex color terhadap efek angin pada animasi prosedural 3d model vegetasi musaceae serta parameter vertex color yang tepat untuk menghasilkan animasi 3d model vegetasi musaceae realistis. Hasil akhir yang di capai adalah meneliti apakah perubahan parameter vertex color dapat mempengaruhi bentuk animasi procedural 3d vegetasi musaceae serta pengaruh dari vertex color terhadap efek angin pada animasi prosedural 3d model vegetasi Musaceae. Berdasarkan pengamat dan perbandingan pada pengujian 5 sample vertex color diperoleh hasil bahwa perubahan parameter vertex color dapat mempengaruhi bentuk animasi procedural 3d vegetasi musaceae serta di peroleh kesimpulan Sample No.5 merupakan parameter vertex color yang tepat untuk menghasilkan animasi 3d model vegetasi Musaceae yang realistis. Kata kunci—3D, Animasi Prosedural, Vegetation
Renormalization of Hierarchically Interacting Isotropic Diffusions
den Hollander, F.; Swart, J. M.
1998-10-01
We study a renormalization transformation arising in an infinite system of interacting diffusions. The components of the system are labeled by the N-dimensional hierarchical lattice ( N≥2) and take values in the closure of a compact convex set bar D subset {R}^d (d ≥slant 1). Each component starts at some θ ∈ D and is subject to two motions: (1) an isotropic diffusion according to a local diffusion rate g: bar D to [0,infty ] chosen from an appropriate class; (2) a linear drift toward an average of the surrounding components weighted according to their hierarchical distance. In the local mean-field limit N→∞, block averages of diffusions within a hierarchical distance k, on an appropriate time scale, are expected to perform a diffusion with local diffusion rate F ( k) g, where F^{(k)} g = (F_{c_k } circ ... circ F_{c_1 } ) g is the kth iterate of renormalization transformations F c ( c>0) applied to g. Here the c k measure the strength of the interaction at hierarchical distance k. We identify F c and study its orbit ( F ( k) g) k≥0. We show that there exists a "fixed shape" g* such that lim k→∞ σk F ( k) g = g* for all g, where the σ k are normalizing constants. In terms of the infinite system, this property means that there is complete universal behavior on large space-time scales. Our results extend earlier work for d = 1 and bar D = [0,1], resp. [0, ∞). The renormalization transformation F c is defined in terms of the ergodic measure of a d-dimensional diffusion. In d = 1 this diffusion allows a Yamada-Watanabe-type coupling, its ergodic measure is reversible, and the renormalization transformation F c is given by an explicit formula. All this breaks down in d≥2, which complicates the analysis considerably and forces us to new methods. Part of our results depend on a certain martingale problem being well-posed.
Functional renormalization group approach to neutron matter
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Matthias Drews
2014-11-01
Full Text Available The chiral nucleon-meson model, previously applied to systems with equal number of neutrons and protons, is extended to asymmetric nuclear matter. Fluctuations are included in the framework of the functional renormalization group. The equation of state for pure neutron matter is studied and compared to recent advanced many-body calculations. The chiral condensate in neutron matter is computed as a function of baryon density. It is found that, once fluctuations are incorporated, the chiral restoration transition for pure neutron matter is shifted to high densities, much beyond three times the density of normal nuclear matter.
Renormalization group circuits for gapless states
Swingle, Brian; McGreevy, John; Xu, Shenglong
2016-05-01
We show that a large class of gapless states are renormalization group fixed points in the sense that they can be grown scale by scale using local unitaries. This class of examples includes some theories with a dynamical exponent different from one, but does not include conformal field theories. The key property of the states we consider is that the ground-state wave function is related to the statistical weight of a local statistical model. We give several examples of our construction in the context of Ising magnetism.
Analytic continuation of functional renormalization group equations
Floerchinger, Stefan
2012-01-01
Functional renormalization group equations are analytically continued from imaginary Matsubara frequencies to the real frequency axis. On the example of a scalar field with O(N) symmetry we discuss the analytic structure of the flowing action and show how it is possible to derive and solve flow equations for real-time properties such as propagator residues and particle decay widths. The formalism conserves space-time symmetries such as Lorentz or Galilei invariance and allows for improved, self-consistent approximations in terms of derivative expansions in Minkowski space.
Renormalization group formulation of large eddy simulation
Yakhot, V.; Orszag, S. A.
1985-01-01
Renormalization group (RNG) methods are applied to eliminate small scales and construct a subgrid scale (SSM) transport eddy model for transition phenomena. The RNG and SSM procedures are shown to provide a more accurate description of viscosity near the wall than does the Smagorinski approach and also generate farfield turbulence viscosity values which agree well with those of previous researchers. The elimination of small scales causes the simultaneous appearance of a random force and eddy viscosity. The RNG method permits taking these into account, along with other phenomena (such as rotation) for large-eddy simulations.
The exact renormalization group and approximation solutions
Morris, T R
1994-01-01
We investigate the structure of Polchinski's formulation of the flow equations for the continuum Wilson effective action. Reinterpretations in terms of I.R. cutoff greens functions are given. A promising non-perturbative approximation scheme is derived by carefully taking the sharp cutoff limit and expanding in `irrelevancy' of operators. We illustrate with two simple models of four dimensional $\\lambda \\varphi^4$ theory: the cactus approximation, and a model incorporating the first irrelevant correction to the renormalized coupling. The qualitative and quantitative behaviour give confidence in a fuller use of this method for obtaining accurate results.
Perturbative and nonperturbative renormalization in lattice QCD
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Goeckeler, M. [Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Horsley, R. [University of Edinburgh (United Kingdom). School of Physics and Astronomy; Perlt, H. [Leipzig Univ. (DE). Institut fuer Theoretische Physik] (and others)
2010-03-15
We investigate the perturbative and nonperturbative renormalization of composite operators in lattice QCD restricting ourselves to operators that are bilinear in the quark fields (quark-antiquark operators). These include operators which are relevant to the calculation of moments of hadronic structure functions. The nonperturbative computations are based on Monte Carlo simulations with two flavors of clover fermions and utilize the Rome-Southampton method also known as the RI-MOM scheme. We compare the results of this approach with various estimates from lattice perturbation theory, in particular with recent two-loop calculations. (orig.)