Adjoint SU(2) with four fermion interactions
DEFF Research Database (Denmark)
Rantaharju, Jarno; Drach, Vincent; Pica, Claudio
2016-01-01
Four fermion interactions appear in many models of Beyond Standard Model physics. In Technicolour and composite Higgs models Standard Model fermion masses can be generated by four fermion terms. They are also expected to modify the dynamics of the new strongly interacting sector. In particular in...
Mass anomalous dimension in SU(2) with six fundamental fermions
DEFF Research Database (Denmark)
Bursa, Francis; Del Debbio, Luigi; Keegan, Liam
2010-01-01
We simulate SU(2) gauge theory with six massless fundamental Dirac fermions. We measure the running of the coupling and the mass in the Schroedinger Functional scheme. We observe very slow running of the coupling constant. We measure the mass anomalous dimension gamma, and find it is between 0.13...
Large-volume results in SU(2) with adjoint fermions
Del Debbio, Luigi; Pica, Claudio; Patella, Agostino; Rago, Antonio; Roman, Sabin
2014-01-01
Taming finite-volume effects is a crucial ingredient in order to identify the existence of IR fixed points. We present the latest results from our numerical simulations of SU(2) gauge theory with 2 Dirac fermions in the adjoint representation on large volumes. We compare with previous results, and extrapolate to thermodynamic limit when possible.
Finite volume effects in SU(2) with two adjoint fermions
DEFF Research Database (Denmark)
Del Debbio, Luigi; Lucini, Biagio; Patella, Agostino
2011-01-01
Many evidences from lattice simulations support the idea that SU(2) with two Dirac flavors in the adjoint representation (also called Minimal Walking Technicolor) is IR conformal. A possible way to see this is through the behavior of the spectrum of the mass-deformed theory. When fermions are mas...
Large-volume results in SU(2) with adjoint fermions
DEFF Research Database (Denmark)
Del Debbio, Luigi; Lucini, Biagio; Pica, Claudio
2013-01-01
Taming finite-volume effects is a crucial ingredient in order to identify the existence of IR fixed points. We present the latest results from our numerical simulations of SU(2) gauge theory with 2 Dirac fermions in the adjoint representation on large volumes. We compare with previous results, an...
Mass anomalous dimension in SU(2) with six fundamental fermions
Energy Technology Data Exchange (ETDEWEB)
Bursa, Francis, E-mail: fwb22@cam.ac.u [Jesus College, Cambridge, CB5 8BL (United Kingdom); Del Debbio, Luigi; Keegan, Liam [SUPA, School of Astrophysics and Astronomy, University of Edinburgh, Edinburgh, EH9 3JZ (United Kingdom); Pica, Claudio [CP3-Origins, University of Southern Denmark Odense, 5230 M (Denmark); Pickup, Thomas [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford, OX1 3NP (United Kingdom)
2011-02-07
We simulate SU(2) gauge theory with six massless fundamental Dirac fermions. We measure the running of the coupling and the mass in the Schroedinger Functional scheme. We observe very slow running of the coupling constant. We measure the mass anomalous dimension {gamma}, and find it is between 0.135 and 1.03 in the range of couplings consistent with the existence of an IR fixed point.
Finite volume effects in SU(2) with two adjoint fermions
Patella, Agostino; Lucini, Biagio; Pica, Claudio; Rago, Antonio
2011-01-01
Many evidences from lattice simulations support the idea that SU(2) with two Dirac flavors in the adjoint representation (also called Minimal Walking Technicolor) is IR conformal. A possible way to see this is through the behavior of the spectrum of the mass-deformed theory. When fermions are massive, a mass-gap is generated and the theory is confined. IR-conformality is recovered in the chiral limit: masses of particles vanish in the chiral limit, while their ratios stay finite. In order to trust this analysis one has to relay on the infinite volume extrapolation. We will discuss the finite volume effects on the mesonic spectrum, investigated by varying the size of the lattice and by changing the boundary conditions for the fields.
Mass anomalous dimension and running of the coupling in SU(2) with six fundamental fermions
DEFF Research Database (Denmark)
Bursa, Francis; Del Debbio, Luigi; Keegan, Liam
2010-01-01
We simulate SU(2) gauge theory with six massless fundamental Dirac fermions. By using the Schr\\"odinger Functional method we measure the running of the coupling and the fermion mass over a wide range of length scales. We observe very slow running of the coupling and construct an estimator for the...
Running coupling in SU(2) gauge theory with two adjoint fermions
DEFF Research Database (Denmark)
Rantaharju, Jarno; Rantalaiho, Teemu; Rummukainen, Kari
2016-01-01
We study SU(2) gauge theory with two Dirac fermions in the adjoint representation of the gauge group on the lattice. Using clover improved Wilson fermion action with hypercubic truncated stout smearing we perform simulations at larger coupling than before. We measure the evolution of the coupling...
Scattering lengths in SU(2) gauge theory with two fundamental fermions
DEFF Research Database (Denmark)
Arthur, R.; Drach, V.; Hansen, Martin Rasmus Lundquist
2014-01-01
We investigate non perturbatively scattering properties of Goldstone Bosons in an SU(2) gauge theory with two Wilson fermions in the fundamental representation. Such a theory can be used to build extensions of the Standard Model that unifies Technicolor and pseudo Goldstone composite Higgs models...
Confining vs. conformal scenario for SU(2) with 2 adjoint fermions. Mesonic spectrum
DEFF Research Database (Denmark)
Pica, Claudio; Del Debbio, Luigi; Lucini, Biagio
2010-01-01
The Minimal Walking Technicolor (MWT) model, based on the SU(2) gauge group with two Dirac adjoint fermions, is expected to lie close to the lower boundary of the conformal window. As such, it is believed to possess a dynamics different enough from QCD to be a viable candidate for a Technicolor t...
Fundamental fermion interactions via vector bosons of unified SU(2 x SU(4 gauge fields
Directory of Open Access Journals (Sweden)
Eckart eMarsch
2016-02-01
Full Text Available Employing the fermion unification model based on the intrinsic SU(8 symmetry of a generalized Dirac equation, we discuss the fundamental interactions under the SU(8=SU(2$otimes$SU(4 symmetry group. The physics involved can describe all fermions, the leptons (electron and neutrino, and the coloured up and down quarks of the first generation in the standard model (SM by a complex SU(8 octet of Dirac spinor fields. The fermion interactions are found to be mediated by the unified SU(4 and SU(2 vector gauge boson fields, which include the photon, the gluons, and the bosons $Z$ and $W$ as well known from the SM, but also comprise new ones, namely three coloured $X$ bosons carrying a fractional hypercharge of $pm4/3$ and transmuting leptons into quarks and vice versa. The full covariant derivative of the model is derived and discussed. The Higgs mechanism gives mass to the $Z$ and $W$ bosons, but also permits one to derive the mass of the coloured $X$ boson, for which depending on the choice of the values of the coupling constant, the estimates are 35~GeV or 156~GeV, values that are well within reach of the LHC. The scalar Higgs field can also lend masses to the fermions and fix their physical values for given appropriate coupling constants to that field.
Confining vs. conformal scenario for SU(2) with adjoint fermions. Gluonic observables
Patella, Agostino; Lucini, Biagio; Pica, Claudio; Rago, Antonio
2010-01-01
Walking technicolor is a mechanism for electroweak symmetry breaking without Higgs field. The Higgs mechanism is provided by chiral symmetry breaking in the technicolor theory. An essential ingredient is the vicinity to an IR fixed point, which could reconcile technicolor with the electroweak precision tests. SU(2) gauge theory with two Dirac adjoint fermions has been proposed as a candidate for walking technicolor. Understanding whether this theory is confining or IR-conformal is a challenging problem, which can be addressed by means of numerical simulations. We have pointed out that a clean signal for the existence of an IR fixed point in this theory can be obtained by comparing the mesonic and gluonic sectors. We review some technical details of our calculations. Possible systematic errors are discussed.
Higher representations on the lattice: numerical simulations. SU(2) with adjoint fermions
DEFF Research Database (Denmark)
Del Debbio, Luigi; Patella, Agostino; Pica, Claudio
2008-01-01
We discuss the lattice formulation of gauge theories with fermions in arbitrary representations of the color group, and present in detail the implementation of the HMC/RHMC algorithm for simulating dynamical fermions. We discuss the validation of the implementation through an extensive set of tes...
First results for SU(2) Yang-Mills with one adjoint Dirac Fermion
Athenodorou, Andreas; Bergner, Georg; Lucini, Biagio; Patella, Agostino
2013-01-01
We present a first exploratory study of SU(2) gauge theory with one Dirac flavour in the adjoint representation. We provide initial results for the spectroscopy and the anomalous dimension for the chiral condensate. Our investigation indicates that the theory is conformal or near-conformal, with an anomalous dimension of order one. A discussion of the relevance of these findings in relation to walking technicolor scenarios is also presented.
Wilson Fermions with Four Fermion Interactions
Rantaharju, Jarno; Pica, Claudio; Sannino, Francesco
2016-01-01
Four fermion interactions appear in many models of Beyond Standard Model physics. In Technicolour and composite Higgs models Standard Model fermion masses can be generated by four fermion terms. They are also expected to modify the dynamics of the new strongly interacting sector. In particular in technicolour models it has been suggested that they can be used to break infrared conformality and produce a walking theory with a large mass anomalous dimension. We study the SU(2) gauge theory with 2 adjoint fermions and a chirally symmetric four fermion term. We demonstrate chiral symmetry breaking at large four fermion coupling and study the phase diagram of the model.
DEFF Research Database (Denmark)
2011-01-01
This film explores the birth of a new ethnic group, the Gando. The Gando are a Fulfulde-speaking group of slave descendants that emerged politically in the context of democratic decentralisation reform. Today, Gando, who were once seen as a sub-group of Fulani or Baatombu/Boo people, claim...... they should be recognized as a new ethnic group. This challenging claim should be understood as a quest for a full-fledged citizenship. The film presents the testimony of a former slave. His personal trajectory is both singular and archetypical. Entrusted to Fulani people because he was suspected as infant...
Infrared behaviors of SU(2 gauge theory
Directory of Open Access Journals (Sweden)
Tuominen Kimmo
2017-01-01
Full Text Available We will discuss some recent results in the determination of the location of the conformal window in SU(2 gauge theory with Nf fermions in the fundamental representation of the gauge group. In particular, we will demonstrate that the long distance behavior of the continuum theory with Nf = 6 is governed by an infrared stable fixed point.
Tene Me Quia Fugi (Slave Collar).
Strasheim, Lorraine A.
This mini-text is a series of Martial's epigrams on the slave. The epigrams deal with: slave torture, tenderness to a slave, the slave as a curiosity, flogging, the slave as property, a selling point, the slave as a person, sex and the slave, and slaves as gifts. The epigrams come with complete Latin-English vocabularies and reading notes. The…
Heglar, Charles J.
Although slave narratives have enjoyed critical attention as literature and autobiography, when presenting them to undergraduates, there is some confusion--usually centering on the dissimilarities between the narratives and traditional autobiography. The narratives are not as linear, not as focused on personal development; the narrators are not as…
Projected Entangled Pair States with non-Abelian gauge symmetries: An SU(2) study
DEFF Research Database (Denmark)
Zohar, Erez; Wahl, Thorsten B.; Burrello, Michele
2016-01-01
limited to global symmetries, but has also been extended and applied for local symmetries, allowing to use them for the description of states in lattice gauge theories. In this paper we discuss PEPS with a local, SU(2) gauge symmetry, and demonstrate the use of PEPS features and techniques for the study...... of a simple family of many body states with a non-Abelian gauge symmetry. We present, in particular, the construction of fermionic PEPS able to describe both two-color fermionic matter and the degrees of freedom of an SU(2) gauge field with a suitable truncation....
Confronting Thomas Jefferson, Slave Owner.
Blackman, James A.
1992-01-01
Although Thomas Jefferson's view of freedom was the cornerstone of the Declaration of Independence, this founding father owned 170 slaves to run his 5,000 acre plantation. This article describes a unit developed by the Monticello (Virginia) Education Department that teaches secondary students about slave Isaac Jefferson while exposing them to…
An Electroweak-like Theory from Four Fermion Interactions
Huang, Yi-Cheng
2014-01-01
An electroweak-like theory of a broken chiral symmetry that is constructed by the collective modes of fermion pairs from four fermion interactions of one lepton generation is presented. The products of Dirac spinors lead to the separation of the two chiral fermions to couple respectively with two different kinds of polarization states. Because of a broken vacuum, a fermion and an anti-fermion out of the four pair up to form vector bosons, which behave like gauge bosons, such as $W^\\pm$, $Z$ and $\\gamma$ in a group structure of $SU(2)_L\\times U(1)_Y$. The pairing of spinors only allows left-handed fermions to interact with charged bosons to secure the gauge invariance, while, as desired, $Z$-like bosons mediate different weak forces for two chiral fermions and $\\gamma$-like bosons interact freely with fermions.
Mass anomalous dimension of SU(2) using the spectral density method
Suorsa, Joni M; Rantaharju, Jarno; Rantalaiho, Teemu; Rummukainen, Kari; Tuominen, Kimmo; Tähtinen, Sara
2016-01-01
SU(2) with N_f = 6 and N_f = 8 are believed to have an infrared conformal fixed point. We use the spectral density method cross referenced with the mass step scaling method to evaluate the coupling constant dependence of the mass anomalous dimension for massless HEX smeared, clover improved Wilson fermions with Schr\\"odinger functional boundary conditions.
Gradient flow and IR fixed point in SU(2) with Nf=8 flavors
DEFF Research Database (Denmark)
Leino, Viljami; Karavirta, Tuomas; Rantaharju, Jarno
2015-01-01
We study the running of the coupling in SU(2) gauge theory with 8 massless fundamental representation fermion flavours, using the gradient flow method with the Schr\\"odinger functional boundary conditions. Gradient flow allows us to measure robust continuum limit for the step scaling function...
The gradient flow running coupling in SU2 with 8 flavors
DEFF Research Database (Denmark)
Rantaharju, Jarno; Karavirta, Tuomas; Leino, Viljami
2014-01-01
We present preliminary results of the gradient flow running coupling with Dirichlet boundary condition in the SU(2) gauge theory with 8 fermion flavours. Improvements to the gradient flow measurement allow us to obtain a robust continuum limit. The results are consistent with perturbative running...
Master-slave micromanipulator method
Energy Technology Data Exchange (ETDEWEB)
Morimoto, A.K.; Kozlowski, D.M.; Charles, S.T.; Spalding, J.A.
1999-12-14
A method is disclosed based on precision X-Y stages that are stacked. Attached to arms projecting from each X-Y stage are a set of two axis gimbals. Attached to the gimbals is a rod, which provides motion along the axis of the rod and rotation around its axis. A dual-planar apparatus that provides six degrees of freedom of motion precise to within microns of motion. Precision linear stages along with precision linear motors, encoders, and controls provide a robotics system. The motors can be remotized by incorporating a set of bellows on the motors and can be connected through a computer controller that will allow one to be a master and the other one to be a slave. Position information from the master can be used to control the slave. Forces of interaction of the slave with its environment can be reflected back to the motor control of the master to provide a sense of force sensed by the slave. Forces import onto the master by the operator can be fed back into the control of the slave to reduce the forces required to move it.
SU(2) Gauge Theory with Two Fundamental Flavours
DEFF Research Database (Denmark)
Arthur, Rudy; Drach, Vincent; Hansen, Martin
2016-01-01
(Goldstone) Higgs theories to several intriguing types of dark matter candidates, such as the SIMPs. We improve our previous lattice analysis [1] by adding more data at light quark masses, at two additional lattice spacings, by determining the lattice cutoff via a Wilson flow measure of the $w_0$ parameter......We investigate the continuum spectrum of the SU(2) gauge theory with $N_f=2$ flavours of fermions in the fundamental representation. This model provides a minimal template which is ideal for a wide class of Standard Model extensions featuring novel strong dynamics that range from composite......, and by measuring the relevant renormalisation constants non-perturbatively in the RI'-MOM scheme. Our results for the lightest isovector states in the vector and axial channels, in units of the pseudoscalar decay constant, are $m_V/F_{\\rm{PS}}\\sim 13.1(2.2)$ and $m_A/F_{\\rm{PS}}\\sim 14.5(3.6)$ (combining...
Projected Entangled Pair States with non-Abelian gauge symmetries: An SU(2) study
Energy Technology Data Exchange (ETDEWEB)
Zohar, Erez, E-mail: erez.zohar@mpq.mpg.de [Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching (Germany); Wahl, Thorsten B. [Rudolf Peierls Centre for Theoretical Physics, Oxford, 1 Keble Road, OX1 3NP (United Kingdom); Burrello, Michele, E-mail: michele.burrello@mpq.mpg.de [Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching (Germany); Cirac, J. Ignacio [Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching (Germany)
2016-11-15
Over the last years, Projected Entangled Pair States have demonstrated great power for the study of many body systems, as they naturally describe ground states of gapped many body Hamiltonians, and suggest a constructive way to encode and classify their symmetries. The PEPS study is not only limited to global symmetries, but has also been extended and applied for local symmetries, allowing to use them for the description of states in lattice gauge theories. In this paper we discuss PEPS with a local, SU(2) gauge symmetry, and demonstrate the use of PEPS features and techniques for the study of a simple family of many body states with a non-Abelian gauge symmetry. We present, in particular, the construction of fermionic PEPS able to describe both two-color fermionic matter and the degrees of freedom of an SU(2) gauge field with a suitable truncation.
Fermion masses through four-fermion condensates
Ayyar, Venkitesh
2016-01-01
Fermion masses can be generated through four-fermion condensates when symmetries prevent fermion bilinear condensates from forming. This less explored mechanism of fermion mass generation is responsible for making four reduced staggered lattice fermions massive at strong couplings in a lattice model with a local four-fermion coupling. The model has a massless fermion phase at weak couplings and a massive fermion phase at strong couplings. In particular there is no spontaneous symmetry breaking of any lattice symmetries in both these phases. Recently it was discovered that in three space-time dimensions there is a direct second order phase transition between the two phases. Here we study the same model in four space-time dimensions and find results consistent with the existence of a narrow intermediate phase with fermion bilinear condensates, that separates the two asymptotic phases by continuous phase transitions.
Fractal dimension of the topological charge density distribution in SU(2) lattice gluodynamics
Energy Technology Data Exchange (ETDEWEB)
Buividovich, P.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Institute for Theoretical and Experimental Physics ITEP, Moscow (Russian Federation); Kalaydzhyan, T. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Institute for Theoretical and Experimental Physics ITEP, Moscow (Russian Federation); Polikarpov, M.I. [Institute for Theoretical and Experimental Physics ITEP, Moscow (Russian Federation)
2011-11-15
We study the effect of cooling on the spatial distribution of the topological charge density in quenched SU(2) lattice gauge theory with overlap fermions. We show that as the gauge field configurations are cooled, the Hausdorff dimension of regions where the topological charge is localized gradually changes from d=2/3 towards the total space dimension. Hence the cooling procedure destroys some of the essential properties of the topological charge distribution. (orig.)
Leontaris, George K
1999-01-01
In the context of the free-fermionic formulation of the heterotic superstring, we construct a three generation N=1 supersymmetric SU(4)xSU(2)LxSU(2)R model supplemented by an SU(8) hidden gauge symmetry and five Abelian factors. The symmetry breaking to the standard model is achieved using vacuum expectation values of a Higgs pair in (4bar,2R)+(4,2R) at a high scale. One linear combination of the Abelian symmetries is anomalous and is broken by vacuum expectation values of singlet fields along the flat directions of the superpotential. All consistent string vacua of the model are completely classified by solving the corresponding system of F- and D-flatness equations including non-renormalizable terms up to sixth order. The requirement of existence of electroweak massless doublets further restricts the phenomenologically viable vacua. The third generation fermions receive masses from the tree-level superpotential. Further, a complete calculation of all non-renormalizable fermion mass terms up to fifth order s...
Wilson Fermions with Four Fermion Interactions
DEFF Research Database (Denmark)
Rantaharju, Jarno; Drach, Vincent; Hietanen, Ari
2015-01-01
We present a lattice study of a four fermion theory, known as Nambu Jona-Lasinio (NJL) theory, via Wilson fermions. Four fermion interactions naturally occur in several extensions of the Standard Model as a low energy parameterisation of a more fundamental theory. In models of dynamical electrowe...
Axial anomalies of Lifshitz fermions
Bakas, Ioannis
2011-01-01
We compute the axial anomaly of a Lifshitz fermion theory with anisotropic scaling z=3 which is minimally coupled to geometry in 3+1 space-time dimensions. We find that the result is identical to the relativistic case using path integral methods. An independent verification is provided by showing with spectral methods that the eta-invariant of the Dirac and Lifshitz fermion operators in three dimensions are equal. Thus, by the integrated form of the anomaly, the index of the Dirac operator still accounts for the possible breakdown of chiral symmetry in non-relativistic theories of gravity. We apply this framework to the recently constructed gravitational instanton backgrounds of Horava-Lifshitz theory and find that the index is non-zero provided that the space-time foliation admits leaves with harmonic spinors. Using Hitchin's construction of harmonic spinors on Berger spheres, we obtain explicit results for the index of the fermion operator on all such gravitational instanton backgrounds with SU(2)xU(1) isom...
Four fermion operators and the search for BSM Physics
Catterall, Simon
2012-01-01
We report on Monte Carlo simulations focused on elucidating the phase structure of a SU(2) gauge theory containing $N_f$ Dirac fermion flavors transforming in the fundamental representation of the group and interacting through an additional chirally invariant four fermion term. Pairs of physical flavors are implemented using the two tastes present in a reduced staggered fermion formulation of the theory with the Yukawa interactions necessary for generating the four fermion term preserving the usual shift symmetries. We observe a crossover in the behavior of the chiral condensate for strong four fermi coupling associated with the generation of a dynamical mass for the fermions. At weak gauge coupling this crossover is consistent with the usual continuous phase transition seen in the pure (ungauged) NJL model. However, if the gauge coupling is strong enough to cause confinement we observe a much more rapid crossover in the chiral condensate consistent with a first order phase transition.
SU(2|2) supersymmetric mechanics
Energy Technology Data Exchange (ETDEWEB)
Ivanov, Evgeny [Joint Institute for Nuclear Research,Dubna, Moscow Region, 141980 (Russian Federation); Lechtenfeld, Olaf [Institut für Theoretische Physik and Riemann Center for Geometry and Physics,Leibniz Universität Hannover,Appelstraße 2, 30167 Hannover (Germany); Sidorov, Stepan [Joint Institute for Nuclear Research,Dubna, Moscow Region, 141980 (Russian Federation)
2016-11-07
We introduce a new kind of non-relativistic N= 8 supersymmetric mechanics, associated with worldline realizations of the supergroup SU(2|2) treated as a deformation of flat N= 8, d=1 supersymmetry. Various worldline SU(2|2) superspaces are constructed as coset manifolds of this supergroup, and the corresponding superfield techniques are developed. For the off-shell SU(2|2) multiplets (3,8,5), (4,8,4) and (5,8,3), we construct and analyze the most general superfield and component actions. Common features are mass oscillator-type terms proportional to the deformation parameter and a trigonometric realization of the superconformal group OSp(4{sup ∗}|4) in the conformal cases. For the simplest (5,8,3) model the quantization is performed.
Leontaris, George K
1999-01-01
In the context of the free-fermionic formulation of the heterotic superstring, we construct a three-generation N = 1 supersymmetric SU(4) x SU(2) sub L x SU(2) sub R model supplemented by an SU(8) hidden gauge symmetry and five Abelian factors. The symmetry breaking to the standard model is achieved using vacuum expectation values of a Higgs pair in (4,2 sub R) + (4-bar,2 sub R) at a high scale. One linear combination of the Abelian symmetries is anomalous and is broken by vacuum expectation values of singlet fields along the flat directions of the superpotential. All consistent string vacua of the model are completely classified by solving the corresponding system of F- and D-flatness equations including non-renormalizable terms up to sixth order. The requirement of existence of electroweak massless doublets imposes further restrictions to the phenomenologically viable vacua. The third generation fermions receive masses from the tree-level superpotential. Further, a complete calculation of all non-renormaliz...
Braiding with Majorana fermions
Kauffman, Louis H.; Lomonaco, Samuel J.
2016-05-01
This paper is an introduction to relationships between topology, quantum computing and the properties of fermions. In particular we study the remarkable unitary braid group representations associated with Majorana fermions.
Dynamical Generation of the Gauged SU(2) Linear Sigma Model
Delbourgo, R.; Scadron, M. D.
The fermion and meson sectors of the quark-level SU(2) linear sigma model are dynamically generated from a meson-quark Lagrangian, with the quark (q) and meson (σ, π) fields all treated as elementary, having neither bare masses nor expectation values. In the chiral limit, the masses are predicted to be mq = fπg, mπ = 0, mσ = 2mq, and we also find that the quark-meson coupling is g =2π /√ {Nc}, the three-meson coupling is g' =mσ 2 /2fπ =2gmq and the four-meson coupling is λ = 2g2 = g‧/fπ, where fπ ≃ 90 MeV is the pion decay constant and Nc = 3 is the color number. By gauging this model one can generate the couplings to the vector mesons ρ and A1, including the quark-vector coupling constant gρ = 2π, gρππ, gA1ρπ and the masses mρ 700 MeV, mA1˜= √ {3} mρ ; of course the vector and axial currents remain conserved throughout.
d -wave superconductivity in boson+fermion dimer models
Goldstein, Garry; Chamon, Claudio; Castelnovo, Claudio
2017-05-01
We present a slave-particle mean-field study of the mixed boson+fermion quantum dimer model introduced by Punk et al. [Proc. Natl. Acad. Sci. USA 112, 9552 (2015), 10.1073/pnas.1512206112] to describe the physics of the pseudogap phase in cuprate superconductors. Our analysis naturally leads to four charge e fermion pockets whose total area is equal to the hole doping p for a range of parameters consistent with the t -J model for high-temperature superconductivity. Here we find that the dimers are unstable to d -wave superconductivity at low temperatures. The region of the phase diagram with d -wave rather than s -wave superconductivity matches well with the appearance of the four fermion pockets. In the superconducting regime, the dispersion contains eight Dirac cones along the diagonals of the Brillouin zone.
A correction to the Immirzi parameter of SU(2 spin networks
Directory of Open Access Journals (Sweden)
M. Sadiq
2015-02-01
Full Text Available The elegant predictions of loop quantum gravity are obscured by the free Immirzi parameter (γ. Dreyer (2003, considering the asymptotic quasinormal modes spectrum of a black hole, proposed that γ may be fixed by letting the j=1 transitions of spin networks as the dominant processes contributing to the black hole area, as opposed to the expected j=1/2 transitions. This suggested that the gauge group of the theory might be SO(3 rather than SU(2. Corichi (2003, maintaining SU(2 as the underlying gauge group, and invoking the principle of local fermion-number conservation, reported the same value of γ for j=1 processes as obtained by Dreyer. In this note, preserving the SU(2 structure of the theory, and considering j=1 transitions as the dominant processes, we point out that the value of γ is in fact twice the value reported by these authors. We arrive at this result by assuming the asymptotic quasinormal modes themselves as dynamical systems obeying SU(2 symmetry.
Simple Z2 lattice gauge theories at finite fermion density
Prosko, Christian; Lee, Shu-Ping; Maciejko, Joseph
2017-11-01
Lattice gauge theories are a powerful language to theoretically describe a variety of strongly correlated systems, including frustrated magnets, high-Tc superconductors, and topological phases. However, in many cases gauge fields couple to gapless matter degrees of freedom, and such theories become notoriously difficult to analyze quantitatively. In this paper we study several examples of Z2 lattice gauge theories with gapless fermions at finite density, in one and two spatial dimensions, that are either exactly soluble or whose solution reduces to that of a known problem. We consider complex fermions (spinless and spinful) as well as Majorana fermions and study both theories where Gauss' law is strictly imposed and those where all background charge sectors are kept in the physical Hilbert space. We use a combination of duality mappings and the Z2 slave-spin representation to map our gauge theories to models of gauge-invariant fermions that are either free, or with on-site interactions of the Hubbard or Falicov-Kimball type that are amenable to further analysis. In 1D, the phase diagrams of these theories include free-fermion metals, insulators, and superconductors, Luttinger liquids, and correlated insulators. In 2D, we find a variety of gapped and gapless phases, the latter including uniform and spatially modulated flux phases featuring emergent Dirac fermions, some violating Luttinger's theorem.
Infrared conformality and bulk critical points: SU(2) with heavy adjoint quarks
Lucini, Biagio; Rago, Antonio; Rinaldi, Enrico
2013-01-01
The lattice phase structure of a gauge theory can be a serious obstruction to Monte Carlo studies of its continuum behaviour. This issue is particularly delicate when numerical studies are performed to determine whether a theory is in a (near-)conformal phase. In this work we investigate the heavy mass limit of the SU(2) gauge theory with Nf=2 adjoint fermions and its lattice phase diagram, showing the presence of a critical point ending a line of first order bulk phase transition. The relevant gauge observables and the low-lying spectrum are monitored in the vicinity of the critical point with very good control over different systematic effects. The scaling properties of masses and susceptibilities open the possibility that the effective theory at criticality is a scalar theory in the universality class of the four-dimensional Gaussian model. This behaviour is clearly different from what is observed for SU(2) gauge theory with two dynamical adjoint fermions, whose (near-)conformal numerical signature is henc...
Antiferromagnetism in the Hubbard model using a cluster slave-spin method
Lee, Wei-Cheng; Lee, Ting-Kuo
2017-09-01
The cluster slave-spin method is introduced to systematically investigate the solutions of the Hubbard model including the symmetry-broken phases. In this method, the electron operator is factorized into a fermionic spinon describing the physical spin and a slave-spin describing the charge fluctuations. Following the U (1 ) formalism derived by Yu and Si [Phys. Rev. B 86, 085104 (2012), 10.1103/PhysRevB.86.085104], it is shown that the self-consistent equations to explore various symmetry-broken density wave states can be constructed in general with a cluster of multiple slave-spin sites. We employ this method to study the antiferromagnetic (AFM) state in the single band Hubbard model with the two- and four-site clusters of slave spins. While the Hubbard gap, the charge gap due to the doubly occupied states, scales with the Hubbard interaction U as expected, the AFM gap Δ , the gap in the spinon dispersion in the AFM state, exhibits a crossover from the weak- to strong-coupling behaviors as U increases. Our cluster slave-spin method reproduces not only the traditional mean-field behavior of Δ ˜U in the weak-coupling limit, but also the behavior of Δ ˜t2/U predicted by the superexchange mechanism in the strong-coupling limit. In addition, the holon-doublon correlator as functions of U and doping x is also computed, which exhibits a strong tendency toward the holon-doublon binding in the strong coupling regime. We further show that the quasiparticle weight obtained by the cluster slave-spin method is in a good agreement with the generalized Gutzwiller approximation in both AFM and paramagnetic states, and the results can be improved beyond the generalized Gutzwiller approximation as the cluster is enlarged from a single site to four sites. Our results demonstrate that the cluster slave-spin method can be a powerful tool to systematically investigate the strongly correlated system.
Confining vs. conformal scenario for SU(2) with 2 adjoint fermions. Gluonic observables
DEFF Research Database (Denmark)
Del Debbio, Luigi; Lucini, Biagio; Patella, Agostino
2010-01-01
Walking technicolor is a mechanism for electroweak symmetry breaking without Higgs field. The Higgs mechanism is provided by chiral symmetry breaking in the technicolor theory. An essential ingredient is the vicinity to an IR fixed point, which could reconcile technicolor with the electroweak...
Static solutions of SU(2)-Higgs theory
Energy Technology Data Exchange (ETDEWEB)
Yaffe, L.G. (Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (US))
1989-11-15
The structure and stability of static spherically symmetric solutions in the SU(2)-Higgs theory are examined using both analytic and numerical methods. Accurate results are presented for the energy and instability growth rates of the sphaleron'' solution as a function of the Higgs-boson mass. The sphaleron is shown to undergo an infinite sequence of bifurcations as the Higgs-boson mass is increased, starting at {ital M}{sub {ital H}}=12M{sub W}. New deformed sphaleron'' solutions emerge from each of these bifurcations. These deformed sphalerons are not charge-conjugation invariant, have non-half-integral winding numbers, and are lower in energy than the original sphaleron. Hence, for sufficiently large Higgs-boson mass, minimal-energy paths connecting inequivalent vacuum states do not pass through the original sphaleron configuration.
Energy Technology Data Exchange (ETDEWEB)
Hue, L.T. [Duy Tan University, Institute of Research and Development, Da Nang City (Viet Nam); Vietnam Academy of Science and Technology, Institute of Physics, Hanoi (Viet Nam); Arbuzov, A.B. [Joint Institute for Nuclear Researches, Bogoliubov Laboratory for Theoretical Physics, Dubna (Russian Federation); Ngan, N.T.K. [Cantho University, Department of Physics, Cantho (Viet Nam); Vietnam Academy of Science and Technology, Graduate University of Science and Technology, Hanoi (Viet Nam); Long, H.N. [Ton Duc Thang University, Theoretical Particle Physics and Cosmology Research Group, Ho Chi Minh City (Viet Nam); Ton Duc Thang University, Faculty of Applied Sciences, Ho Chi Minh City (Viet Nam)
2017-05-15
The neutrino and Higgs sectors in the SU(2){sub 1} x SU(2){sub 2} x U(1){sub Y} model with lepton-flavor non-universality are discussed. We show that active neutrinos can get Majorana masses from radiative corrections, after adding only new singly charged Higgs bosons. The mechanism for the generation of neutrino masses is the same as in the Zee models. This also gives a hint to solving the dark matter problem based on similar ways discussed recently in many radiative neutrino mass models with dark matter. Except the active neutrinos, the appearance of singly charged Higgs bosons and dark matter does not affect significantly the physical spectrum of all particles in the original model. We indicate this point by investigating the Higgs sector in both cases before and after singly charged scalars are added into it. Many interesting properties of physical Higgs bosons, which were not shown previously, are explored. In particular, the mass matrices of charged and CP-odd Higgs fields are proportional to the coefficient of triple Higgs coupling μ. The mass eigenstates and eigenvalues in the CP-even Higgs sector are also presented. All couplings of the SM-like Higgs boson to normal fermions and gauge bosons are different from the SM predictions by a factor c{sub h}, which must satisfy the recent global fit of experimental data, namely 0.995 < vertical stroke c{sub h} vertical stroke < 1. We have analyzed a more general diagonalization of gauge boson mass matrices, then we show that the ratio of the tangents of the W-W{sup '} and Z-Z{sup '} mixing angles is exactly the cosine of the Weinberg angle, implying that number of parameters is reduced by 1. Signals of new physics from decays of new heavy fermions and Higgs bosons at LHC and constraints of their masses are also discussed. (orig.)
Hue, L. T.; Arbuzov, A. B.; Ngan, N. T. K.; Long, H. N.
2017-05-01
The neutrino and Higgs sectors in the { SU(2) }_1 × { SU(2) }_2 × { U(1) }_Y model with lepton-flavor non-universality are discussed. We show that active neutrinos can get Majorana masses from radiative corrections, after adding only new singly charged Higgs bosons. The mechanism for the generation of neutrino masses is the same as in the Zee models. This also gives a hint to solving the dark matter problem based on similar ways discussed recently in many radiative neutrino mass models with dark matter. Except the active neutrinos, the appearance of singly charged Higgs bosons and dark matter does not affect significantly the physical spectrum of all particles in the original model. We indicate this point by investigating the Higgs sector in both cases before and after singly charged scalars are added into it. Many interesting properties of physical Higgs bosons, which were not shown previously, are explored. In particular, the mass matrices of charged and CP-odd Higgs fields are proportional to the coefficient of triple Higgs coupling μ . The mass eigenstates and eigenvalues in the CP-even Higgs sector are also presented. All couplings of the SM-like Higgs boson to normal fermions and gauge bosons are different from the SM predictions by a factor c_h, which must satisfy the recent global fit of experimental data, namely 0.995Z-Z' mixing angles is exactly the cosine of the Weinberg angle, implying that number of parameters is reduced by 1. Signals of new physics from decays of new heavy fermions and Higgs bosons at LHC and constraints of their masses are also discussed.
Light Kaluza Klein States in Randall-Sundrum Models with Custodial SU(2)
Energy Technology Data Exchange (ETDEWEB)
Carena, Marcela; /Fermilab; Ponton, Eduardo; /Columbia U.; Santiago, Jose; /Fermilab; Wagner, Carlos E.M.; /Argonne /Chicago U., EFI /KICP, Chicago
2006-07-01
We consider Randall-Sundrum scenarios based on SU(2){sub L} x SU(2){sub R} and a discrete parity exchanging L with R. The custodial and parity symmetries can be used to make the tree level contribution to the T parameter and the anomalous couplings of the bottom quark to the Z very small. We show that the resulting quantum numbers typically induce a negative T parameter at one loop that, together with the positive value of the S parameter, restrict considerably these models. There are nevertheless regions of parameter space that successfully reproduce the fit to electroweak precision observables with light Kaluza-Klein excitations accessible at colliders. We consider models of gauge-Higgs unification that implement the custodial and parity symmetries and find that the electroweak data singles out a very well defined region in parameter space. In this region one typically finds light gauge boson Kaluza-Klein excitations as well as light SU(2){sub L} singlet, and sometimes also doublet, fermionic states, that mix with the top quark, and that may yield interesting signatures at future colliders.
Entangled SU(2) and SU(1,1) coherent states
Wang, Xiao-Guang; Sanders, Barry C.; Pan, Shao-Hua
2000-01-01
Entangled SU(2) and SU(1,1) coherent states are developed as superpositions of multiparticle SU(2) and SU(1,1) coherent states. In certain cases, these are coherent states with respect to generalized su(2) and su(1,1) generators, and multiparticle parity states arise as a special case. As a special example of entangled SU(2) coherent states, entangled binomial states are introduced and these entangled binomial states enable the contraction from entangled SU(2) coherent states to entangled har...
Muslim Slaves and Freedmen in Medieval Portugal
Soyer, François
2007-01-01
The study of slavery in medieval Portugal has focused almost exclusively on the status and fate of the sub-Saharan Africans who started to arrive in the kingdom from 1441 onwards. The work of A. C. de C. M Saunders, A Social History of Black Slaves and Freedmen in Portugal 1441-1555 (Cambridge University Press, 1982) has been particularly important in this respect. In stark contrast to this, the fate of the substantial number of Muslim slaves who lived and worked in Portuga...
Slaves, Sex, and Transgression in Greek Old Comedy
Walin, Daniel Christopher
2012-01-01
This dissertation examines the often surprising role of the slave characters of Greek Old Comedy in sexual humor, building on work I began in my 2009 Classical Quarterly article ("An Aristophanic Slave: Peace 819-1126"). The slave characters of New and Roman comedy have long been the subject of productive scholarly interest; slave characters in Old Comedy, by contrast, have received relatively little attention (the sole extensive study being Stefanis 1980). Yet a closer look at the ancestors ...
Four Fermion Interactions in Non-Abelian Gauge Theory
Catterall, Simon
2013-01-01
We continue our earlier study of the phase structure of a SU(2) gauge theory whose action contains additional chirally invariant four fermion interactions. Our lattice theory uses a reduced staggered fermion formalism to generate two Dirac flavors in the continuum limit. In the current study we have tried to reduce lattice spacing and taste breaking effects by using an improved fermion action incorporating stout smeared links. As in our earlier study we observe two regimes; for weak gauge coupling the chiral condensate behaves as an order parameter differentiating a phase at small four fermi coupling where the condensate vanishes from a phase at strong four fermi coupling in which chiral symmetry is spontaneously broken. This picture changes qualitatively when the gauge coupling is strong enough to cause confinement; in this case we observe a first order phase transition for some critical value of the four fermi coupling associated with a strong enhancement of the chiral condensate. We observe that this criti...
THE PUNISHMENT OF SLAVES IN EARLY CHRISTIANITY: THE ...
African Journals Online (AJOL)
various methods for punishment directed towards the slave body. Finally, the article more specifically .... He explains: “[S]lavery is the result of sin. And this is why we do not find the word slave in any .... Most importantly, punishment was a key method for instilling habits of obedience into slaves. (Glancy 2010a:63-80). 4.
Slave Labor Camps of the Third Reich.
Stone, Adolf
1983-01-01
Describes the ground rules used by Nazi architects in choosing the sites for slave labor camps. While some, like Auschwitz, became extermination camps, others also produced armaments. One camp, Theresienstadt, became a "model" camp to show to reporters and Red Cross representatives. (CS)
Driving with head-slaved camera system
Oving, A.B.; Erp, J.B.F. van
2001-01-01
In a field experiment, we tested the effectiveness of a head-slaved camera system for driving an armoured vehicle under armour. This system consists of a helmet-mounted display (HMD), a headtracker, and a motion platform with two cameras. Subjects performed several driving tasks on paved and in
Triplet fermions and Dirac fermions in borophene
Ezawa, Motohiko
2017-07-01
Borophene is a monolayer materials made of boron. A perfect planar boropehene called β12 borophene has Dirac cones and they are well reproduced by a tight-binding model according to recent experimental and first-principles calculation results. We explicitly derive a Dirac theory for β12 borophene. Dirac cones are gapless when the inversion symmetry exists, while they are gapped when it is broken. In addition, three-band touching points emerge together with pseudospin triplet fermions when all transfer energy is equal and all onsite energy is equal. The three-band touching is slightly resolved otherwise. We construct effective three-band theories for triplet fermions. We also study the edge states of borophene nanoribbons, which show various behaviors depending on the way of edge terminations.
$SU(2)$ gauge theory with two fundamental flavours: scalar and pseudoscalar spectrum
Arthur, Rudy; Hietanen, Ari; Pica, Claudio; Sannino, Francesco
2016-01-01
We investigate the scalar and pseudoscalar spectrum of the $SU(2)$ gauge theory with $N_f=2$ flavours of fermions in the fundamental representation using non perturbative lattice simulations. We provide first benchmark estimates of the mass of the lightest $0(0^{+})$ ($\\sigma$), $0(0^{-})$ ($\\eta'$) and $1(0^+)$ ($a_0$) states, including estimates of the relevant disconnected contributions. We find $m_{a_0}/F_{\\rm{PS}}= 16.7(4.9)$, $m_\\sigma/F_{\\rm{PS}}=19.2(10.8)$ and $m_{\\eta'}/F_{\\rm{PS}} = 12.8(4.7)$. These values for the masses of light scalar states provide crucial information for composite extensions of the Standard Model from the unified Fundamental Composi te Higgs-Technicolor theory \\cite{Cacciapaglia:2014uja} to models of composite dark matter.
Fermionic Linear Optics and Matchgates
Knill, E.
2001-01-01
Fermionic linear optics is efficiently classically simulatable. Here it is shown that the set of states achievable with fermionic linear optics and particle measurements is the closure of a low dimensional Lie group. The weakness of fermionic linear optics and measurements can therefore be explained and contrasted with the strength of bosonic linear optics with particle measurements. An analysis of fermionic linear optics is used to show that the two-qubit matchgates and the simulatable match...
Unification with mirror fermions
Directory of Open Access Journals (Sweden)
Triantaphyllou George
2014-04-01
Full Text Available We present a new framework unifying interactions in nature by introducing mirror fermions, explaining the hierarchy between the weak scale and the coupling unification scale, which is found to lie close to Planck energies. A novel process leading to the emergence of symmetry is proposed, which not only reduces the arbitrariness of the scenario proposed but is also followed by significant cosmological implications. Phenomenology includes the probability of detection of mirror fermions via the corresponding composite bosonic states and the relevant quantum corrections at the LHC.
Slave Prices in the Lower South, 1722-1815
Peter C. Mancall; Joshua L. Rosenbloom; Thomas Weiss
2000-01-01
Using data from samples of probate inventories we construct a series of slave prices for Low Country South Carolina and Georgia covering the period 1722-1815. Using these data we examine variations in slave prices by age and sex, as well as geographic variations between and within the two colonies/states. Nominal slave prices more than doubled between 1722/29 and 1810/15. In real terms, however, there was essentially no change in slave prices deflated either by a general consumer price index,...
Orbifolds, fuzzy spheres and chiral fermions
Chatzistavrakidis, Athanasios; Zoupanos, George
2010-01-01
Starting with a N=4 supersymmetric Yang-Mills theory in four dimensions with gauge group SU(3N) we perform an orbifold projection leading to a N=1 supersymmetric SU(N)^3 Yang-Mills theory with matter supermultiplets in bifundamental representations of the gauge group, which is chiral and anomaly free. Subsequently, we search for vacua of the projected theory which can be interpreted as spontaneously generated twisted fuzzy spheres. We show that by adding the appropriate soft supersymmetry breaking terms we can indeed reveal such vacua. Three cases are studied, where the gauge group is spontaneously broken further to the low-energy gauge groups SU(4)xSU(2)xSU(2), SU(4)^3 and SU(3)^3. Such models behave in intermediate scales as higher-dimensional theories with a finite Kaluza-Klein tower, while their low-energy physics is governed by the corresponding zero-modes and exhibit chirality in the fermionic sector. The most interesting case from the phenomenological point of view turns out to be the SU(3)^3 unified t...
Interacting composite fermions
DEFF Research Database (Denmark)
nrc762, nrc762
2016-01-01
Numerical studies by Wójs, Yi, and Quinn have suggested that an unconventional fractional quantum Hall effect is plausible at filling factors ν=1/3 and 1/5, provided the interparticle interaction has an unusual form for which the energy of two fermions in the relative angular momentum three channel...
Fermions, wigs, and attractors
Energy Technology Data Exchange (ETDEWEB)
Gentile, L.G.C., E-mail: lgentile@pd.infn.it [DISIT, Università del Piemonte Orientale, via T. Michel, 11, Alessandria 15120 (Italy); Dipartimento di Fisica “Galileo Galilei”, Università di Padova, via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova, via Marzolo 8, 35131 Padova (Italy); Grassi, P.A., E-mail: pgrassi@mfn.unipmn.it [DISIT, Università del Piemonte Orientale, via T. Michel, 11, Alessandria 15120 (Italy); INFN, Gruppo Collegato di Alessandria, Sezione di Torino (Italy); Marrani, A., E-mail: alessio.marrani@fys.kuleuven.be [ITF KU Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium); Mezzalira, A., E-mail: andrea.mezzalira@ulb.ac.be [Physique Théorique et Mathématique Université Libre de Bruxelles, C.P. 231, 1050 Bruxelles (Belgium)
2014-05-01
We compute the modifications to the attractor mechanism due to fermionic corrections. In N=2,D=4 supergravity, at the fourth order, we find terms giving rise to new contributions to the horizon values of the scalar fields of the vector multiplets.
Muslim Slaves and Freedmen in Medieval Portugal
Directory of Open Access Journals (Sweden)
Soyer, François
2007-12-01
Full Text Available The study of slavery in medieval Portugal has focused almost exclusively on the status and fate of the sub-Saharan Africans who started to arrive in the kingdom from 1441 onwards. The work of A. C. de C. M Saunders, A Social History of Black Slaves and Freedmen in Portugal 1441-1555 (Cambridge University Press, 1982 has been particularly important in this respect. In stark contrast to this, the fate of the substantial number of Muslim slaves who lived and worked in Portugal during the medieval period has to a large extent been overlooked. Using documentary evidence obtained from the national Portuguese archives, this article proposes to analyse in detail the origins of these slaves, their economic and social role and the laws that were promulgated to control them and their owners. The status of freedmen and manumission practices are also closely studied.
El estudio de la esclavitud en el Portugal medieval ha sido dominado por estudios sobre los esclavos oriundos del África subsahariana que comenzaron a ser importados en aquel reino desde 1441. La obra de A. C. de C. M. Saunders, A Social History of Black Slaves and Freedmen in Portugal 1441-1555 (Cambridge University Press, 1982 ha sido particularmente importante a este respecto. En contraste con esta situación, se sabe relativamente poco de los esclavos musulmanes en el reino medieval de Portugal. Utilizando nuevas fuentes documentales del archivo nacional portugués, este artículo se propone examinar los orígenes de estos esclavos musulmanes y su posición económica y social en el Portugal del medievo, así como las leyes reales que fueron promulgadas para controlar a los esclavos y a sus dueños. La posición social de los libertos y las prácticas de manumisión serán también estudiadas.
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
Effective SU(2) theory for the pseudogap state
Montiel, X.; Kloss, T.; Pépin, C.
2017-03-01
This paper exposes in a detailed manner the recent findings about the SU(2) scenario for the underdoped phase of the cuprate superconductors. The SU(2) symmetry is formulated as a rotation between the d -wave superconducting (SC) phase and a d -wave charge order. We define the operators responsible for the SU(2) rotations and we derive the nonlinear σ model associated with it. In this framework, we demonstrate that SU(2) fluctuations are massless in finite portions of the Brillouin zone corresponding to the antinodal regions (0 ,π ) and (π ,0 ). We argue that the presence of SU(2) fluctuations in the antinodal region leads to the opening of Fermi arcs around the Fermi surface and to the formation of the pseudogap. Moreover, we show that SU(2) fluctuations lead, in turn, to the emergence of a finite momentum SC order—or pair density wave (PDW)—and more importantly to a new kind of excitonic particle-hole pairs liquid, the resonant excitonic state (RES), which is made of patches of preformed particle-hole pairs with multiple momenta. When the RES liquid becomes critical, we demonstrate that electronic scattering through the critical modes leads to anomalous transport properties. This new finding can account for the strange metal (SM) phase at finite temperature, on the right-hand side of the SC dome, shedding light on another notoriously mysterious part of the phase diagram of the cuprates.
Fermionic T-duality in fermionic double space
Directory of Open Access Journals (Sweden)
B. Nikolić
2017-04-01
Full Text Available In this article we offer the interpretation of the fermionic T-duality of the type II superstring theory in double space. We generalize the idea of double space doubling the fermionic sector of the superspace. In such doubled space fermionic T-duality is represented as permutation of the fermionic coordinates θα and θ¯α with the corresponding fermionic T-dual ones, ϑα and ϑ¯α, respectively. Demanding that T-dual transformation law has the same form as initial one, we obtain the known form of the fermionic T-dual NS–R and R–R background fields. Fermionic T-dual NS–NS background fields are obtained under some assumptions. We conclude that only symmetric part of R–R field strength and symmetric part of its fermionic T-dual contribute to the fermionic T-duality transformation of dilaton field and analyze the dilaton field in fermionic double space. As a model we use the ghost free action of type II superstring in pure spinor formulation in approximation of constant background fields up to the quadratic terms.
SU(4)-SU(2) crossover and spin-filter properties of a double quantum dot nanosystem
Lopes, V.; Padilla, R. A.; Martins, G. B.; Anda, E. V.
2017-06-01
The SU(4)-SU(2) crossover, driven by an external magnetic field h , is analyzed in a capacitively coupled double quantum dot device connected to independent leads. As one continuously charges the dots from empty to quarter filled, by varying the gate potential Vg, the crossover starts when the magnitude of the spin polarization of the double quantum dot, as measured by - , becomes finite. Although the external magnetic field breaks the SU(4) symmetry of the Hamiltonian, the ground state preserves it in a region of Vg, where - =0 . Once the spin polarization becomes finite, it initially increases slowly until a sudden change occurs, in which (polarization direction opposite to the magnetic field) reaches a maximum and then decreases to negligible values abruptly, at which point an orbital SU(2) ground state is fully established. This crossover from one Kondo state, with emergent SU(4) symmetry, where spin and orbital degrees of freedom all play a role, to another, with SU(2) symmetry, where only orbital degrees of freedom participate, is triggered by a competition between g μBh , the energy gain by the Zeeman-split polarized state and the Kondo temperature TKS U (4 ), the gain provided by the SU(4) unpolarized Kondo-singlet state. At fixed magnetic field, the knob that controls the crossover is the gate potential, which changes the quantum dots occupancies. If one characterizes the occurrence of the crossover by Vgmax, the value of Vg where reaches a maximum, one finds that the function f relating the Zeeman splitting, Bmax, which corresponds to Vgmax, i.e., Bmax=f (Vgmax) , has a similar universal behavior to that of the function relating the Kondo temperature to Vg. In addition, our numerical results show that near the SU(4) Kondo temperature and for relatively small magnetic fields the device has a ground state that restricts the electronic population at the dots to be spin polarized along the magnetic field. These two facts introduce very efficient spin
Supersymmetry Breaking Threshold Corrections in the $SU(4)\\times SU(2)_L\\times SU(2)_R$ Model
Korakianitis, O.; Tracas, N. D.
1993-01-01
We evaluate the SUSY and top threshold effects in the context of the MSSM and the string derived model based on SU(4)$\\times$SU(2)$_L\\times$SU(2)$_R$. In both cases we run the two loop RGEs and determine the lower bounds of the supersymmetric particle masses, dictated by the experimentally accepted regions of the values of the low energy parameters.
Why is Polygyny More Prevalent in Western Africa?: An African Slave Trade Perspective
Dalton, John T.; Leung, Tin Cheuk
2011-01-01
Polygyny rates are higher in western Africa than in eastern Africa. The African slave trades help explain this difference. More male slaves were exported in the transatlantic slave trades from western Africa, while more female slaves were exported in the Indian Ocean slave trades from eastern Africa. The slave trades led to prolonged periods of abnormal sex ratios, which affected the rates of polygyny across Africa. In order to assess these claims, we present evidence from a variety of source...
Thomas Jefferson and Slaves: Teaching an American Paradox. Lesson Plan.
Fehn, Bruce
2000-01-01
Provides 11 primary sources that enable students to contemplate how Thomas Jefferson and his slaves produced a culture and community at Monticello (Virginia) and his other plantations. Focuses on Jefferson's relationship with his slaves, particularly addressing Sally Hemming's relationship with Jefferson, in order to study the complicated history…
[The presence of emancipated people among slave-owners].
Luna, F V; Da Costa I Del, N
1980-07-01
The proportion of free and emancipated people among the slave-owning population of Minas Gerais, Brazil, between 1738 and 1811 is studied. The percent of the slave population belonging to those social levels is also examined according to sex, age group, and area of origin. (summary in ENG)
Agonistic Struggle: Master-Slave Dialogues in Humanities Supervision
Grant, Barbara M.
2008-01-01
Hegel's master and slave is a significant archetype for graduate research supervision. The master-slave relation vividly exemplifies the hierarchical bond that ties supervisor and student together. Such a confronting view of supervision provides a counterbalance to contemporary emphases on equality between supervisor and student. In what follows,…
Effects of a potential fourth fermion generation on the Higgs boson mass bounds
Gerhold, P.; Jansen, K.; Kallarackal, J.
2010-01-01
We study the effect of a potential fourth fermion generation on the upper and lower Higgs boson mass bounds. This investigation is based on the numerical evaluation of a chirally invariant lattice Higgs-Yukawa model emulating the same Higgs-fermion coupling structure as in the Higgs sector of the electroweak Standard Model. In particular, the considered model obeys a Ginsparg-Wilson version of the underlying $SU(2)_L\\times U(1)_Y$ symmetry, being a global symmetry here due to the neglection o...
Phase diagram of the lattice SU(2) Higgs model
Energy Technology Data Exchange (ETDEWEB)
Bonati, C., E-mail: bonati@df.unipi.i [Dipartimento di Fisica and INFN, Pisa (Italy); Cossu, G., E-mail: cossu@post.kek.j [Scuola Normale Superiore and INFN, Pisa (Italy); D' Elia, M., E-mail: Massimo.Delia@ge.infn.i [Dipartimento di Fisica and INFN, Genova (Italy); Di Giacomo, A., E-mail: digiaco@df.unipi.i [Dipartimento di Fisica and INFN, Pisa (Italy)
2010-03-21
We perform a detailed study of the phase diagram of the lattice Higgs SU(2) model with fixed Higgs field length. Consistently with previsions based on the Fradkin-Shenker theorem we find a first order transition line with an endpoint whose position we determined. The diagram also shows cross-over lines: the cross-over corresponding to the pure SU(2) bulk is also present at nonzero coupling with the Higgs field and merges with the one that continues the line of first order transition beyond the critical endpoint. At high temperature the first order line becomes a crossover, whose position moves by varying the temperature.
Polyakov loop percolation and deconfinement in SU(2) gauge theory
Fortunato, S.; Satz, H.
2000-03-01
The deconfinement transition in /SU(2) gauge theory and the magnetization transition in the Ising model belong to the same universality class. The critical behaviour of the Ising model can be characterized either as spontaneous breaking of the Z2 symmetry of spin states or as percolation of appropriately defined spin clusters. We show that deconfinement in /SU(2) gauge theory can be specified as percolation of Polyakov loop clusters with Fortuin-Kasteleyn bond weights, leading to the same (Onsager) critical exponents as the conventional order-disorder description based on the Polykov loop expectation value.
Equivariant spectral triples on the quantum SU(2) group
Chakraborty, Partha Sarathi; Pal, Arupkumar
2002-01-01
We characterize all equivariant odd spectral triples for the quantum SU(2) group acting on its L_2-space and having a nontrivial Chern character. It is shown that the dimension of an equivariant spectral triple is at least three, and given any element of the K-homology group of SU_q(2), there is an equivariant odd spectral triple of dimension 3 inducing that element. The method employed to get equivariant spectral triples in the quantum case is then used for classical SU(2), and we prove that...
Synchronization Analysis of Master-Slave Probabilistic Boolean Networks.
Lu, Jianquan; Zhong, Jie; Li, Lulu; Ho, Daniel W C; Cao, Jinde
2015-08-28
In this paper, we analyze the synchronization problem of master-slave probabilistic Boolean networks (PBNs). The master Boolean network (BN) is a deterministic BN, while the slave BN is determined by a series of possible logical functions with certain probability at each discrete time point. In this paper, we firstly define the synchronization of master-slave PBNs with probability one, and then we investigate synchronization with probability one. By resorting to new approach called semi-tensor product (STP), the master-slave PBNs are expressed in equivalent algebraic forms. Based on the algebraic form, some necessary and sufficient criteria are derived to guarantee synchronization with probability one. Further, we study the synchronization of master-slave PBNs in probability. Synchronization in probability implies that for any initial states, the master BN can be synchronized by the slave BN with certain probability, while synchronization with probability one implies that master BN can be synchronized by the slave BN with probability one. Based on the equivalent algebraic form, some efficient conditions are derived to guarantee synchronization in probability. Finally, several numerical examples are presented to show the effectiveness of the main results.
Patterns of reproduction in slave-making ants
Herbers, J M; Stuart, R. J.
1998-01-01
Sex ratios in slave-making ants have been posed as important test cases for the hypothesis that eusociality evolved via kin selection in insects. Trivers and Hare proposed that sex ratios in slave-makers should reflect the queen's interests whereas sex ratios in free-living host ants should reflect the workers' interests. We analyse patterns of allocation to males versus females, as well as allocation to growth versus reproduction for slave-making ants in the tribe Formicoxenini. We find litt...
't Hooft loop and the phases of SU(2) LGT
Burgio, Giuseppe
2013-01-01
We analyze the vacuum structure of SU(2) lattice gauge theories in D=2,3,4, concentrating on the stability of 't Hooft loops. High precision calculations have been performed in D=3; similar results hold also for D=4 and D=2. We discuss the impact of our findings on the continuum limit of Yang-Mills theories.
The SU(2)-Higgs model on asymmetric lattices
Csikor, Ferenc
1996-01-01
We calculate the {\\cal O}(g^2,\\lambda) corrections to the coupling anisotropies of the SU(2)-Higgs model on lattices with asymmetric lattice spacings. These corrections are obtained by a one-loop calculation requiring the rotational invariance of the gauge- and Higgs-boson propagators in the continuum limit.
Compactifications of IIA supergravity on SU(2)-structure manifolds
Energy Technology Data Exchange (ETDEWEB)
Spanjaard, B.
2008-07-15
In this thesis, we study compactifications of type IIA supergravity on six-dimensional manifolds with an SU(2)-structure. A general study of six-dimensional manifolds with SU(2)-structure shows that IIA supergravity compactified on such a manifold should yield a four-dimensional gauged N=4 supergravity. We explicitly derive the bosonic spectrum, gauge transformations and action for IIA supergravity compactified on two different manifolds with SU(2)-structure, one of which also has an H{sup (3)}{sub 10}-flux, and confirm that the resulting four-dimensional theories are indeed N=4 gauged supergravities. In the second chapter, we study an explicit construction of a set of SU(2)-structure manifolds. This construction involves a Scherk-Schwarz duality twist reduction of the half-maximal six-dimensional supergravity obtained by compactifying IIA supergravity on a K3. This reduction results in a gauged N=4 four-dimensional supergravity, where the gaugings can be divided into three classes of parameters. We relate two of the classes to parameters we found before, and argue that the third class of parameters could be interpreted as a mirror flux. (orig.)
Non-Local effective SU(2) Polyakov-loop models from inverse Monte-Carlo methods
Bahrampour, Bardiya; von Smekal, Lorenz
2016-01-01
The strong-coupling expansion of the lattice gauge action leads to Polyakov-loop models that effectively describe gluodynamics at low temperatures, and together with the hopping expansion of the fermion determinant provides insight into the QCD phase diagram at finite density and low temperatures, although for rather heavy quarks. At higher temperatures the strong-coupling expansion breaks down and it is expected that the interactions between Polyakov loops become non-local. Here, we therefore test how well pure SU(2) gluodynamics can be mapped onto different non-local Polyakov models with inverse Monte-Carlo methods. We take into account Polyakov loops in higher representations and gradually add interaction terms at larger distances. We are particularly interested in extrapolating the range of non-local terms in sufficiently large volumes and higher representations. We study the characteristic fall-off in strength of the non-local couplings with the interaction distance, and its dependence on the gauge coupl...
SU(2) Gauge Theory with Two Fundamental Flavours: a Minimal Template for Model Building
Arthur, Rudy; Hansen, Martin; Hietanen, Ari; Pica, Claudio; Sannino, Francesco
2016-01-01
We investigate the continuum spectrum of the SU(2) gauge theory with $N_f=2$ flavours of fermions in the fundamental representation. This model provides a minimal template which is ideal for a wide class of Standard Model extensions featuring novel strong dynamics that range from composite (Goldstone) Higgs theories to several intriguing types of dark matter candidates, such as the SIMPs. We improve our previous lattice analysis [1] by adding more data at light quark masses, at two additional lattice spacings, by determining the lattice cutoff via a Wilson flow measure of the $w_0$ parameter, and by measuring the relevant renormalisation constants non-perturbatively in the RI'-MOM scheme. Our results for the lightest isovector states in the vector and axial channels, in units of the pseudoscalar decay constant, are $m_V/F_{\\rm{PS}}\\sim 13.1(2.2)$ and $m_A/F_{\\rm{PS}}\\sim 14.5(3.6)$ (combining statistical and systematic errors). In the context of the composite (Goldstone) Higgs models, our result for the spin-...
Slaves, Contrabands, and Freedmen: Union Policy in the Civil War
National Research Council Canada - National Science Library
Howard, Michelle
1998-01-01
This study examines Union slave policy in the Civil War. Prior to the initiation of hostilities, President Abraham Lincoln stated that the conflict between the states was over the preservation of the Union, and not over...
Estimation of stochastic environment force for master–slave robotic ...
Indian Academy of Sciences (India)
Estimation of stochastic environment force for master–slave robotic system ... Environmental noise; parameter estimation; trajectories; MLE; CRLB; Fisher informa ... Department of Electrical Engineering, Delhi Technological University, Delhi 110042, India; Division of Manufacturing Processes and Automation Engineering, ...
Patterns of reproduction in slave-making ants
Herbers, J. M.; Stuart, R. J.
1998-01-01
Sex ratios in slave-making ants have been posed as important test cases for the hypothesis that eusociality evolved via kin selection in insects. Trivers and Hare proposed that sex ratios in slave-makers should reflect the queen's interests whereas sex ratios in free-living host ants should reflect the workers' interests. We analyse patterns of allocation to males versus females, as well as allocation to growth versus reproduction for slave-making ants in the tribe Formicoxenini. We find little support for the hypothesis of exclusive queen control; instead, our results implicate queen–worker conflict in slave-making ants, both over male allocation ratios and over allocation to growth versus reproduction.
The Slave Family, Women -- A Reassessment of Matriarchy, Emasculation, Weakness
Genovese, Eugene D.
1974-01-01
Slave families and rural Southern black families afterward were remarkably stable; black women during and after slavery were supportive of their men; man and wife were close to today's ideal of individual strength and development. (Author/KM)
The family tree is not cut: marriage among slaves in eighteenth-century Puerto Rico
Directory of Open Access Journals (Sweden)
David Stark
2002-01-01
Full Text Available Examines the frequency of slave marriage in 18th-c. Puerto Rico, through family reconstitution based on parish baptismal, marriage, and death registers. Author first sketches the development of slavery, and the work regimens and conditions of the not yet sugar-dominated slavery in Puerto Rico. Then, he describes the religious context and social implications of marriage among slaves, and discusses, through an example, spousal selection patterns, and further focuses on age and seasonality of the slave marriages. He explains that marriage brought some legal advantages for slaves, such as the prohibited separation, by sale, of married slaves. In addition, he explores how slaves pursued marital strategies in order to manipulate material conditions. He concludes from the results that in the 18th c. marriage among slaves was not uncommon, and appear to have been determined mostly by the slaves own choice, with little direct intervention by masters. Most slaves married other slaves, with the same owner.
Slaves to Big Data. Or Are We?
Directory of Open Access Journals (Sweden)
Mireille Hildebrandt
2013-10-01
Full Text Available
In this contribution, the notion of Big Data is discussed in relation to the monetisation of personal data. The claim of some proponents, as well as adversaries, that Big Data implies that ‘n = all’, meaning that we no longer need to rely on samples because we have all the data, is scrutinised and found to be both overly optimistic and unnecessarily pessimistic. A set of epistemological and ethical issues is presented, focusing on the implications of Big Data for our perception, cognition, fairness, privacy and due process. The article then looks into the idea of user-centric personal data management to investigate to what extent it provides solutions for some of the problems triggered by the Big Data conundrum. Special attention is paid to the core principle of data protection legislation, namely purpose binding. Finally, this contribution seeks to inquire into the influence of Big Data politics on self, mind and society, and asks how we can prevent ourselves from becoming slaves to Big Data.
SU(2)-monopoles, curves with symmetries and Ramanujan's heritage
Braden, Harry W.; Ènol'skii, Viktor Z.
2010-08-01
We develop the Ercolani-Sinha construction of SU(2) monopoles for a five-parameter family of centred charge 3 monopoles. In particular we show how to solve the transcendental constraints arising on the spectral curve. For a class of symmetric curves the transcendental constraints become a number-theoretic problem and a recently proven identity of Ramanujan provides a solution. Bibliography: 36 titles.
Fermions in worldline holography
Dietrich, Dennis D.; Koenigstein, Adrian
2017-09-01
We analyze the worldline holographic framework for fermions. Worldline holography is based on the observation that in the worldline approach to quantum field theory, sources of a quantum field theory over Mink4 naturally form a field theory over AdS5 to all orders in the elementary fields and in the sources. Schwinger's proper time of the worldline formalism automatically appears with the physical four spacetime dimensions in an AdS5 geometry. The worldline holographic effective action in general and the proper-time profiles of the sources in particular solve a renormalization group equation. By taking into account sources up to spin one, we reconstruct seminal holographic models. Considering spin two confirms AdS5 as a consistent background.
Feng, Baojie; Sugino, Osamu; Liu, Ro-Ya; Zhang, Jin; Yukawa, Ryu; Kawamura, Mitsuaki; Iimori, Takushi; Kim, Howon; Hasegawa, Yukio; Li, Hui; Chen, Lan; Wu, Kehui; Kumigashira, Hiroshi; Komori, Fumio; Chiang, Tai-Chang; Meng, Sheng; Matsuda, Iwao
2017-03-03
Honeycomb structures of group IV elements can host massless Dirac fermions with nontrivial Berry phases. Their potential for electronic applications has attracted great interest and spurred a broad search for new Dirac materials especially in monolayer structures. We present a detailed investigation of the β_{12} sheet, which is a borophene structure that can form spontaneously on a Ag(111) surface. Our tight-binding analysis revealed that the lattice of the β_{12} sheet could be decomposed into two triangular sublattices in a way similar to that for a honeycomb lattice, thereby hosting Dirac cones. Furthermore, each Dirac cone could be split by introducing periodic perturbations representing overlayer-substrate interactions. These unusual electronic structures were confirmed by angle-resolved photoemission spectroscopy and validated by first-principles calculations. Our results suggest monolayer boron as a new platform for realizing novel high-speed low-dissipation devices.
Feng, Baojie; Sugino, Osamu; Liu, Ro-Ya; Zhang, Jin; Yukawa, Ryu; Kawamura, Mitsuaki; Iimori, Takushi; Kim, Howon; Hasegawa, Yukio; Li, Hui; Chen, Lan; Wu, Kehui; Kumigashira, Hiroshi; Komori, Fumio; Chiang, Tai-Chang; Meng, Sheng; Matsuda, Iwao
2017-03-01
Honeycomb structures of group IV elements can host massless Dirac fermions with nontrivial Berry phases. Their potential for electronic applications has attracted great interest and spurred a broad search for new Dirac materials especially in monolayer structures. We present a detailed investigation of the β12 sheet, which is a borophene structure that can form spontaneously on a Ag(111) surface. Our tight-binding analysis revealed that the lattice of the β12 sheet could be decomposed into two triangular sublattices in a way similar to that for a honeycomb lattice, thereby hosting Dirac cones. Furthermore, each Dirac cone could be split by introducing periodic perturbations representing overlayer-substrate interactions. These unusual electronic structures were confirmed by angle-resolved photoemission spectroscopy and validated by first-principles calculations. Our results suggest monolayer boron as a new platform for realizing novel high-speed low-dissipation devices.
Fermions as generalized Ising models
Energy Technology Data Exchange (ETDEWEB)
Wetterich, C., E-mail: c.wetterich@thphys.uni-heidelberg.de
2017-04-15
We establish a general map between Grassmann functionals for fermions and probability or weight distributions for Ising spins. The equivalence between the two formulations is based on identical transfer matrices and expectation values of products of observables. The map preserves locality properties and can be realized for arbitrary dimensions. We present a simple example where a quantum field theory for free massless Dirac fermions in two-dimensional Minkowski space is represented by an asymmetric Ising model on a euclidean square lattice.
Quantum Entanglement in Fermionic Lattices
Zanardi, P.
2001-01-01
The Fock space of a system of indistinguishable particles is isomorphic (in a non-unique way) to the state-space of a composite i.e., many-modes, quantum system. One can then discuss quantum entanglement for fermionic as well as bosonic systems. We exemplify the use of this notion -central in quantum information - by studying some e.g., Hubbard,lattice fermionic models relevant to condensed matter physics.
On the p-deformed fermion algebra: Thermodynamics of p-fermion gas
Chung, Won Sang; Hassanabadi, Hassan
2017-11-01
In this paper we introduce the p-deformed fermion algebra as a kind of generalization of the ordinary fermion algebra. We discuss the p-fermion algebra and its representation. We also find the generalized Pauli matrices related to the p-fermion algebra. As applications we discuss the thermodynamics in the canonical ensemble of the p-fermion and the p-fermion gas model.
Yellow fever, Asia and the East African slave trade.
Cathey, John T; Marr, John S
2014-05-01
Yellow fever is endemic in parts of sub-Saharan Africa and South America, yet its principal vectors--species of mosquito of the genus Aedes--are found throughout tropical and subtropical latitudes. Phylogenetic analyses indicate that yellow fever originated in Africa and that its spread to the New World coincided with the slave trade, but why yellow fever has never appeared in Asia remains a mystery. None of several previously proposed explanations for its absence there is considered satisfactory. We contrast the trans-Atlantic slave trade, and trade across the Sahara and to the Arabian Peninsula and Mesopotamia, with that to Far East and Southeast Asian ports before abolition of the African slave trade, and before the scientific community understood the transmission vector of yellow fever and the viral life cycle, and the need for shipboard mosquito control. We propose that these differences in slave trading had a primary role in the avoidance of yellow fever transmission into Asia in the centuries before the 20(th) century. The relatively small volume of the Black African slave trade between Africa and East and Southeast Asia has heretofore been largely ignored. Although focal epidemics may have occurred, the volume was insufficient to reach the threshold for endemicity.
Periodic Euclidean solutions of SU(2)-Higgs theory
Energy Technology Data Exchange (ETDEWEB)
Frost, K.L.; Yaffe, L.G. [University of Washington, Department of Physics, Seattle, Washington 98105-1560 (United States)
1999-03-01
We examine periodic, spherically symmetric, classical solutions of SU(2)-Higgs theory in four-dimensional Euclidean space. Classical perturbation theory is used to construct periodic time-dependent solutions in the neighborhood of the static sphaleron. The behavior of the action, as a function of period, changes character depending on the value of the Higgs boson mass. The required pattern of bifurcations of solutions as a function of the Higgs boson mass is examined, and implications for the temperature dependence of the baryon number violation rate in the standard model are discussed. {copyright} {ital 1999} {ital The American Physical Society}
Fermions and gravitational gyrotropy
Helfer, Adam D.
2016-12-01
In conventional general relativity without torsion, high-frequency gravitational waves couple to the chiral number density of spin one-half quanta: the polarization of the waves is rotated by 2 π N5ℓPl2, where N5 is the chiral column density and ℓPl is the Planck length. This means that if a primordial distribution of gravitational waves with E-E or B-B correlations passed through a chiral density of fermions in the very early Universe, an E-B correlation will be generated. This in turn will give rise to E-B and T-B correlations in the cosmic microwave background (CMB). Less obviously but more primitively, the condition Albrecht called "cosmic coherence" would be violated, changing the restrictions on the class of admissible cosmological gravitational waves. This altered class of waves would, generally speaking, probe earlier physics than do the conventional waves; their effects on the CMB would be most pronounced for low (≲100 ) multipoles. Rough estimates indicate that if the tensor-to-scalar ratio is less than about 10-2, it will be hard to constrain a spatially homogeneous primordial N5 by present data.
Growth depression and recovery: the remarkable case of American slaves.
Steckel, R H
1987-01-01
Legislation designed to prevent slave smuggling after 1807 created an extra-ordinary set of documents identifying slaves transported in the coastwise trade by name, age, sex height and colour. Slaves fell below the first or second centile of modern height standards as children but recovered during and after adolescence to exceed the 25th centile as adults. This profile differs remarkably from other populations. Poor pre-natal care, early weaning, food supplements that were nutritionally poor and often contaminated, and a heavy disease load thwarted growth during childhood, but the diet improved substantially when young adolescents entered the labour force. The results show that humans have remarkable capacity for catch-up growth.
SU (2) lattice gauge theory simulations on Fermi GPUs
Cardoso, Nuno; Bicudo, Pedro
2011-05-01
In this work we explore the performance of CUDA in quenched lattice SU (2) simulations. CUDA, NVIDIA Compute Unified Device Architecture, is a hardware and software architecture developed by NVIDIA for computing on the GPU. We present an analysis and performance comparison between the GPU and CPU in single and double precision. Analyses with multiple GPUs and two different architectures (G200 and Fermi architectures) are also presented. In order to obtain a high performance, the code must be optimized for the GPU architecture, i.e., an implementation that exploits the memory hierarchy of the CUDA programming model. We produce codes for the Monte Carlo generation of SU (2) lattice gauge configurations, for the mean plaquette, for the Polyakov Loop at finite T and for the Wilson loop. We also present results for the potential using many configurations (50,000) without smearing and almost 2000 configurations with APE smearing. With two Fermi GPUs we have achieved an excellent performance of 200× the speed over one CPU, in single precision, around 110 Gflops/s. We also find that, using the Fermi architecture, double precision computations for the static quark-antiquark potential are not much slower (less than 2× slower) than single precision computations.
The age-sex structure of the slave population in Harris County, Texas: 1850 and 1860.
Hutchinson, J
1987-10-01
The effect of the slave system on demography can be revealed by examining the age-sex structure of slave populations. The age-sex structure of slaves in Harris County, Texas is investigated using the 1850 and 1860 slave schedules. Median ages for black and mulatto slaves suggest that the population was young. Population pyramids exhibit a narrow base and top with a broad middle. The high proportion of slaves between 10 and 30 years of age and the increase in population size between 1850 and 1860 were mainly related to the importation of slaves and only partly due to natural increase. The data also show that black slaves were older on small plantations while mulattoes were older on larger farms. It is suggested that differential treatment in terms of purchase practices, assignment of tasks, food allocation, and/or differential susceptibility to infectious diseases may account for this pattern.
Fermions on the electroweak string
Moreno, J M; Quirós, Mariano; Moreno, J M; Oaknin, D H; Quiros, M
1995-01-01
We construct a simple class of exact solutions of the electroweak theory including the naked Z--string and fermion fields. It consists in the Z--string configuration (\\phi,Z_\\theta), the {\\it time} and z components of the neutral gauge bosons (Z_{0,3},A_{0,3}) and a fermion condensate (lepton or quark) zero mode. The Z--string is not altered (no feed back from the rest of fields on the Z--string) while fermion condensates are zero modes of the Dirac equation in the presence of the Z--string background (no feed back from the {\\it time} and z components of the neutral gauge bosons on the fermion fields). For the case of the n--vortex Z--string the number of zero modes found for charged leptons and quarks is (according to previous results by Jackiw and Rossi) equal to |n|, while for (massless) neutrinos is |n|-1. The presence of fermion fields in its core make the obtained configuration a superconducting string, but their presence (as well as that of Z_{0,3},A_{0,3}) does not enhance the stability of the Z--stri...
Absence of evidence is no proof : slave resistance under German colonial rule in East Africa
Deutsch, J-G.; Abbink, J.; Bruijn, de M.E.; Walraven, van K.
2003-01-01
This chapter examines the lack of evidence regarding slave resistance in German East Africa and the related question of whether the colonial stereotype of the 'docile slave' is true. It starts with a brief surmise of the history of slavery and an analysis of slave actions in the period concerned
Beyond profitability. The Dutch transatlantic slave trade and its economic impact
van Rossum, Matthias; Fatah-Black, Karwan
2015-01-01
Dutch research into the slave trade and its importance to the Dutch economy has often limited itself to investigating the financial success of slave trading companies, calculating the success of slaving by its profit rates. The central argument made in this article is that grossmargin is a better
The punishment of slaves in early Christianity: the views of some ...
African Journals Online (AJOL)
With few exceptions, many of the Church Fathers approved, in principle, of the punishment of slaves. However, there were very specific guidelines on why, how, and when to punish slaves. The purpose of this article is to analyse more closely how some of the early Church Fathers conceptualised the punishment of slaves.
Estimation of stochastic environment force for master–slave robotic ...
Indian Academy of Sciences (India)
Neelu Nagpal
Estimation of stochastic environment force for master–slave robotic system. NEELU NAGPAL1,*, BHARAT BHUSHAN1 and VIJYANT AGARWAL2. 1 Department of Electrical Engineering, Delhi Technological University, Delhi 110042, India. 2 Division of Manufacturing Processes and Automation Engineering, Netaji Subhas ...
THE PUNISHMENT OF SLAVES IN EARLY CHRISTIANITY: THE ...
African Journals Online (AJOL)
how some of the early Church Fathers conceptualised the punishment of slaves. The study begins, first, by examining ... that the Early Church never formally abolished slavery, with the exception of Gregory of Nyssa's ..... 9 For more on the relation between the physical and psychological aspects of punishment, cf. Patterson ...
Advertising of slave trade in the Romanian principalities
Directory of Open Access Journals (Sweden)
Marian Petcu
2014-12-01
Full Text Available This study deals with the thorny issue of the history of our country – the Gypsy slave trade, as it was presented in the press (1837-1844. We have identified a number of advertisements that reflect the type of trade, its form, prices for slaves, and institutions involved in such transactions. All this information is presented in a variety of contexts: the writings of foreign travelers, responses of public authorities, official documents. Studied documents leave no doubt as to the intention of the authorities to assimilate the Gypsies. There is also highlighted the role of the press as an intermediary in the Gypsy slave trade. Since we are talking about semi-official publications (Cantor de Avis şi Comerţ, Vestitorul Românesc, Albina Românească, it should be understood that these transactions were carried out with the consent of the heads of the relevant state entities. The study also highlights the stages of freeing the slaves.
Human trafficking: a variant of the historic slave trade in ...
African Journals Online (AJOL)
... described as a 'baby factory' in Nigeria. This paper therefore examines some recent issues on kidnapping as well as factors responsible for this criminal act in Nigeria. Sequel to findings, this paper made some recommendations. Keywords: Human trafficking, Human right, Sex workers, Slave trade, Smuggling of people ...
Gravitational leptogenesis in axion inflation with SU(2) gauge field
Maleknejad, Azadeh
2016-12-01
We present an intrinsic leptogenesis mechanism in models of axion inflation with a classical SU(2) gauge field. The gauge field is coupled to the axion with a Chern-Simons interaction and comprises a tiny fraction of the total energy, ρYM/ρtot lesssim epsilon2. However, it has spin-2 fluctuations which breaks the parity and leads to the generation of chiral gravitational waves during inflation. By the gravitational anomaly in SM, it naturally creates a net lepton number density, sufficient to explain the matter asymmetry. We show that this mechanism can generate the observed value of baryon to photon number density in a natural range of parameters and yet has a small chiral tensor power spectrum on large scales.
Dynamic SU(2) structure from seven-branes
Energy Technology Data Exchange (ETDEWEB)
Heidenreich, Ben; McAllister, Liam; /Cornell U., Phys. Dept.; Torroba, Gonzalo; /SLAC /Stanford U., Phys. Dept.
2010-12-16
We obtain a family of supersymmetric solutions of type IIB supergravity with dynamic SU(2) structure, which describe the local geometry near a stack of four D7-branes and one O7-plane wrapping a rigid four-cycle. The deformation to a generalized complex geometry is interpreted as a consequence of nonperturbative effects in the seven-brane gauge theory. We formulate the problem for seven-branes wrapping the base of an appropriate del Pezzo cone, and in the near-stack limit in which the four-cycle is flat, we obtain an exact solution in closed form. Our solutions serve to characterize the local geometry of nonperturbatively-stabilized flux compactifications.
Confinement from semiclassical gluon fields in SU(2) gauge theory
Langfeld, Kurt
2010-01-01
The infrared structure of SU(2) Yang-Mills theory is studied by means of lattice gauge simulations using a new constrained cooling technique. This method reduces the action while all Polyakov lines on the lattice remain unchanged. In contrast to unconstrained cooling, quark confinement is still intact. A study of the Hessian of the Yang-Mills action shows that low action (semi-) classical configurations can be achieved, with a characteristic splitting between collective modes and higher momentum modes. Besides confinement, the semiclassical configurations also support the topological susceptibility and generate spontaneous breakdown of chiral symmetry.We show that they possess a cluster structure of locally mainly (anti-) selfdual objects. By contrast to an instanton or a meron medium, the topological charge of individual clusters is smoothly distributed.
Improved lattice fermion action for heavy quarks
Cho, Yong-Gwi; Jüttner, Andreas; Kaneko, Takashi; Marinkovic, Marina; Noaki, Jun-Ichi; Tsang, Justus Tobias
2015-01-01
We develop an improved lattice action for heavy quarks based on Brillouin-type fermions, that have excellent energy-momentum dispersion relation. The leading discretization errors of $O(a)$ and $O(a^2)$ are eliminated at tree-level. We carry out a scaling study of this improved Brillouin fermion action on quenched lattices by calculating the charmonium energy-momentum dispersion relation and hyperfine splitting. We present a comparison to standard Wilson fermions and domain-wall fermions.
Fermions as generalized Ising models
Directory of Open Access Journals (Sweden)
C. Wetterich
2017-04-01
Full Text Available We establish a general map between Grassmann functionals for fermions and probability or weight distributions for Ising spins. The equivalence between the two formulations is based on identical transfer matrices and expectation values of products of observables. The map preserves locality properties and can be realized for arbitrary dimensions. We present a simple example where a quantum field theory for free massless Dirac fermions in two-dimensional Minkowski space is represented by an asymmetric Ising model on a euclidean square lattice.
Bosonic behavior of entangled fermions
DEFF Research Database (Denmark)
C. Tichy, Malte; Alexander Bouvrie, Peter; Mølmer, Klaus
2012-01-01
Two bound, entangled fermions form a composite boson, which can be treated as an elementary boson as long as the Pauli principle does not affect the behavior of many such composite bosons. The departure of ideal bosonic behavior is quantified by the normalization ratio of multi-composite-boson st......Two bound, entangled fermions form a composite boson, which can be treated as an elementary boson as long as the Pauli principle does not affect the behavior of many such composite bosons. The departure of ideal bosonic behavior is quantified by the normalization ratio of multi...
Directory of Open Access Journals (Sweden)
Saxena Pooja
2017-01-01
Full Text Available A search for high mass Higgs boson of the Minimal Supersymmetric Standard Model decaying into two fermions using the first 2015 data at 13 TeV is presented. The four final decay channels of μτh, eτh, τhτh and eμ is used. The limits on production cross section times branching ratio has been set. Other results from Run1 and different searches and measurements involving Higgs decays fermions will also be reviewed.
Theoretical studies of strongly correlated fermions
Energy Technology Data Exchange (ETDEWEB)
Logan, D. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)
1997-04-01
Strongly correlated fermions are investigated. An understanding of strongly correlated fermions underpins a diverse range of phenomena such as metal-insulator transitions, high-temperature superconductivity, magnetic impurity problems and the properties of heavy-fermion systems, in all of which local moments play an important role. (author).
2-fermion and 4-fermion production at LEP2
van Vulpen, Ivo B
2000-01-01
We present the measurements on 2-fermion and 4-fermion production in e + e - collisions at centre-of-mass energies ranging from 192 to 202 Ge V as collected by the 4 LEP experiments in 1999. For processes with 2-fermions in the final state we present both production cross sections and asymmetries for event samples at low and high effective centre-of-mass energies, where the latter process is sensitive to possible contributions from various non-SM physics, like contact interactions or Z' exchange, and can therefore be used to set limits on parameters in those models. We also report on the measured cross sections for a subset of processes leading to 4 fermions in the final state: pair production of heavy vector bosons w+w- (NC03) and ZZ (NC02) followed by single-W production. A measurement of the leptonic branching ratio of the W-boson is used to extract information on IV c• I
Tata lectures on overlap fermions
Narayanan, R
2011-01-01
Overlap formalism deals with the construction of chiral gauge theories on the lattice. These set of lectures provide a pedagogical introduction to the subject with emphasis on chiral anomalies and gauge field topology. Subtleties associated with the generating functional for gauge theories coupled to chiral fermions are discussed.
Sextet Model with Wilson Fermions
DEFF Research Database (Denmark)
Hansen, Martin; Pica, Claudio
2017-01-01
We present new results from our ongoing study of the SU(3) sextet model with two flavors in the two-index symmetric representation of the gauge group. In the simulations use unimproved Wilson fermions to investigate the infrared properties of the model. We have previously presented results for th...
Fermion mixing in quasifree states
Hannabuss, K C
2003-01-01
Quantum field-theoretic treatments of fermion oscillations are typically restricted to calculations in Fock space. In this letter, we extend the oscillation formulae to include more general quasifree states, and also consider the case when the mixing is not unitary. (letter to the editor)
Fermionic entanglement in itinerant systems
Energy Technology Data Exchange (ETDEWEB)
Zanardi, Paolo [Institute for Scientific Interchange (ISI) Foundation, Torino (Italy); Wang Xiaoguang [Department of Physics and Centre for Advanced Computing-Algorithms and Cryptography, Macquarie University, Sydney, NSW (Australia)
2002-09-20
We study pairwise quantum entanglement in systems of fermions itinerant in a lattice from a second-quantized perspective. Entanglement in the grand-canonical ensemble is studied, both for energy eigenstates and for the thermal state. Relations between entanglement and superconducting correlations are discussed in a BCS-like model and for {eta}-pair superconductivity. (author)
Type IIA orientifolds on SU(2)-structure manifolds
Energy Technology Data Exchange (ETDEWEB)
Danckaert, Thomas
2010-11-15
We investigate the possible supersymmetry-preserving orientifold projections of type IIA string theory on a six-dimensional background with SU(2)-structure. We find two categories of projections which preserve half of the low-energy supersymmetry, reducing the effective theory from an N=4 supergravity theory, to an N=2 supergravity. For these two cases, we impose the projection on the low-energy spectrum and reduce the effective N=4 supergravity action accordingly. We can identify the resulting gauged N=2 supergravity theory and bring the action into canonical form. We compute the scalar moduli spaces and characterize the gauged symmetries in terms of the geometry of these moduli spaces. Due to their origin in N=4 supergravity, which is a highly constrained theory, the moduli spaces are of a very simple form. We find that, for suitable background manifolds, isometries in all scalar sectors can become gauged. The obtained gaugings share many features with those of N=2 supergravities obtained previously from other G-structure compactifications. (orig.)
Topological and magnetic properties of the QCD vacuum probed by overlap fermions
Energy Technology Data Exchange (ETDEWEB)
Braguta, V.V. [Institut Fiziki Vysokikh Ehnergij, Protvino (Russian Federation); Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Buividovich, P.V. [Univ. Regensburg (Germany). ITP; Kalaydzhyan, T. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Polikarpov, M.I. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation)
2013-02-15
We study some of the local CP-odd and magnetic properties of the non-Abelian vacuum with use of overlap fermions within the quenched lattice gauge theory. Among these properties are the following: inhomogeneous spatial distribution of the topological charge density (chirality for massless fermions) in SU(2) gluodynamics (for uncooled gauge configurations the chirality is localized on low-dimensional defects with d=2.3, while a sequence of cooling steps gives rise to four-dimensional instantons and hence a four-dimensional structure of the chirality distribution); finite local fluctuations of the chirality growing with the strength of an external magnetic field; magnetization and susceptibility of the QCD vacuum in SU(3) theory; magnetic catalysis of the chiral symmetry breaking, and the electric conductivity of the QCD vacuum in strong magnetic fields.
Ganaah, Miriam Adwoa
2017-01-01
The thesis describes the role of Christianity in the lives of slaves and slave owners in the American South, pointing out the inconsistencies in the ways slave owners manage the tension between their Christian faith and their way of life as slave holders. The case studies are Harriet Jacobs, "Incidents in the Life of a Slave Girl" and Harriet Wilson's "OUR NIG Sketches from the Life of a Free Black".
Transport properties of chiral fermions
Energy Technology Data Exchange (ETDEWEB)
Puhr, Matthias
2017-04-26
Anomalous transport phenomena have their origin in the chiral anomaly, the anomalous non-conservation of the axial charge, and can arise in systems with chiral fermions. The anomalous transport properties of free fermions are well understood, but little is known about possible corrections to the anomalous transport coefficients that can occur if the fermions are strongly interacting. The main goal of this thesis is to study anomalous transport effects in media with strongly interacting fermions. In particular, we investigate the Chiral Magnetic Effect (CME) in a Weyl Semimetal (WSM) and the Chiral Separation Effect (CSE) in finite-density Quantum Chromodynamics (QCD). The recently discovered WSMs are solid state crystals with low-energy excitations that behave like Weyl fermions. The inter-electron interaction in WSMs is typically very strong and non-perturbative calculations are needed to connect theory and experiment. To realistically model an interacting, parity-breaking WSM we use a tight-binding lattice Hamiltonian with Wilson-Dirac fermions. This model features a non-trivial phase diagram and has a phase (Aoki phase/axionic insulator phase) with spontaneously broken CP symmetry, corresponding to the phase with spontaneously broken chiral symmetry for interacting continuum Dirac fermions. We use a mean-field ansatz to study the CME in spatially modulated magnetic fields and find that it vanishes in the Aoki phase. Moreover, our calculations show that outside of the Aoki phase the electron interaction has only a minor influence on the CME. We observe no enhancement of the magnitude of the CME current. For our non-perturbative study of the CSE in QCD we use the framework of lattice QCD with overlap fermions. We work in the quenched approximation to avoid the sign problem that comes with introducing a finite chemical potential on the lattice. The overlap operator calls for the evaluation of the sign function of a matrix with a dimension proportional to the volume
Conserving slave boson approximations for the anderson model beyond NCA
Kroha, J.; Wölfle, P.; Costi, T. A.; Hirschfeld, P. J.; Muttalib, K. A.
1996-04-01
We derive a general scheme to construct conserving slave boson approximations for the single-impurity Anderson model beyond the noncrossing approximation (NCA). The pseudofermion and slave boson spectral functions are computed in a conserving T-matrix approximation which includes the maximum number of impurity spin flips in each order of the hybridization. In a perturbative evaluation, the singlet channel of the conduction electron-pseudofermion T-matrix has a pole which is renormalized by selfconsistency. As a result, the exponents of the infra-red powerlaw behavior of the pseudoparticle spectral functions are modified w.r.t NCA and depend on the impurity occupation number. We present results for the exponents in the Kondo regime which are consistent with exact values given by the x-ray emission and absorption exponents.
Colonial iron in context: the Trianon slave shackle from Mauritius
DEFF Research Database (Denmark)
Seetah, Krish; Birch, Thomas; Calaon, Diego
2017-01-01
In 2009, part of a ‘slave shackle’ was recovered from archaeological investigations at Trianon, an indentured labourer site on Mauritius dated from the beginning of the nineteenth century. This paper presents the results of a metallurgical assessment of the artefact, thought to represent colonial...... ironwork, a category that has hitherto remained understudied. The results are incorporated into the wider archaeological and historical evidence from Trianon, highlighting the value of studying colonial ironwork in context....
Fundamental fermion masses from deformed SU{sub q}(2) triplets
Energy Technology Data Exchange (ETDEWEB)
Palladino, B.E.; Ferreira, P.L. [Instituto de Fisica Teorica (IFT), Sao Paulo, SP (Brazil)
1996-10-01
A spectrum generating q-algebra, within the framework of SU{sub q}(2), is studied in order to describe the mass spectrum of three generations of quarks and leptons. The SU{sub q}(2) quantum group is a q-deformed extension of SU(2), where q=exp{alpha} (with {alpha} real) is the deformation parameter. In this letter, the essential use of inequivalent representations of SU{sub q}(2) is introduced. A formula for the fermion masses is derived. As an example, a possible scheme which corresponds to two triplets associated to up and down quarks is presented here in some detail. 19 refs., 3 tabs.
The small-volume expansion of gauge theories coupled to massless fermions
van Baal, Pierre
1988-09-01
The small-volume expansion of the low-lying glueball states for SU(2) and SU(3) gauge theory, coupled to massless fermions with periodic and antiperiodic boundary conditions, is determined. For SU(3) with periodic boundary conditions the vacuum is eightfold degenerate and breaks part of the cubic group spontaneously. In all cases the scalar-to-tensor mass ratio mA1++/ mE++ is 1.1 to 1.3 as in the pure-gauge case. We also discuss chiral symmetry.
Uniqueness and permanence dream of Brazilian slave society (XIX Century
Directory of Open Access Journals (Sweden)
Ênio José da Costa Brito
2014-09-01
Full Text Available Within a sequence of studies on slavery in Brazil in 50 years, we have the original study on the political dimension of this slavery from original documentation (Annals and Archives carried forward by Tamis Parron. In the nineteenth century occurred, according to the author, a politicization of slaveholding issues rather than the development of a policy of slavery. The smuggling of slaves and the defense of slavery are too significant to be set aside by historiography events. To Parron, external aspects such as change in American policy slavery and the position of England clearly interfered in the internal politics of Brazil. However, to the author, what existed was not only the defense of slavery with the clear involvement of the state, but also political game scenes by those who had different opinions. Some indirect events such as the Land Law and the domestic slave trade were part of a politicization of the issue of slavery and consequently, the maintenance of the slave society.
Pinning of fermionic occupation numbers.
Schilling, Christian; Gross, David; Christandl, Matthias
2013-01-25
The Pauli exclusion principle is a constraint on the natural occupation numbers of fermionic states. It has been suspected since at least the 1970s, and only proved very recently, that there is a multitude of further constraints on these numbers, generalizing the Pauli principle. Here, we provide the first analytic analysis of the physical relevance of these constraints. We compute the natural occupation numbers for the ground states of a family of interacting fermions in a harmonic potential. Intriguingly, we find that the occupation numbers are almost, but not exactly, pinned to the boundary of the allowed region (quasipinned). The result suggests that the physics behind the phenomenon is richer than previously appreciated. In particular, it shows that for some models, the generalized Pauli constraints play a role for the ground state, even though they do not limit the ground-state energy. Our findings suggest a generalization of the Hartree-Fock approximation.
$b \\to s \\gamma$ Decay in $SU(2)_L \\times SU(2)_R \\times U(1)$ Extensions of the Standard Model
Cho, Peter; Misiak, Mikolaj
1993-01-01
The rare radiative decay $b \\to s \\gamma$ is studied in $SU(2)_L \\times SU(2)_R \\times U(1)$ extensions of the Standard Model. Matching conditions for coefficients of operators appearing in the low energy effective Hamiltonian for this process are derived, and QCD corrections to these coefficients are analyzed. The $b \\to s \\gamma$ decay rate is then calculated and compared with the corresponding Standard Model result. We find that observable deviations from Standard Model predictions can occ...
Pu, Songyang; Wu, Ying-Hai; Jain, J. K.
2017-11-01
We achieve an explicit construction of the lowest Landau level (LLL) projected wave functions for composite fermions in the periodic (torus) geometry. To this end, we first demonstrate how the vortex attachment of the composite fermion (CF) theory can be accomplished in the torus geometry to produce the "unprojected" wave functions satisfying the correct (quasi)periodic boundary conditions. We then consider two methods for projecting these wave functions into the LLL. The direct projection produces valid wave functions but can be implemented only for very small systems. The more powerful and more useful projection method of Jain and Kamilla fails in the torus geometry because it does not preserve the periodic boundary conditions and thus takes us out of the original Hilbert space. We have succeeded in constructing a modified projection method that is consistent with both the periodic boundary conditions and the general structure of the CF theory. This method is valid for a large class of states of composite fermions, called "proper states," which includes the incompressible ground states at electron filling factors ν =n/2 p n +1 , their charged and neutral excitations, and also the quasidegenerate ground states at arbitrary filling factors of the form ν =ν/*2pν*+1 , where n and p are integers and ν* is the CF filling factor. Comparison with exact results known for small systems for the ground and excited states at filling factors ν =1 /3 , 2/5, and 3/7 demonstrates our LLL-projected wave functions to be extremely accurate representations of the actual Coulomb eigenstates. Our construction enables the study of large systems of composite fermions on the torus, thereby opening the possibility of investigating numerous interesting questions and phenomena.
Duality group actions on fermions
Energy Technology Data Exchange (ETDEWEB)
Pantev, Tony [Department of Mathematics, University of Pennsylvania,David Rittenhouse Laboratory, 209 South 33rd Street, Philadelphia, PA 19104-6395 (United States); Sharpe, Eric [Department of Physics MC 0435, Virginia Tech,850 West Campus Drive, Blacksburg, VA 24061 (United States)
2016-11-29
In this short paper we look at the action of T-duality and string duality groups on fermions, in maximally-supersymmetric theories and related theories. Briefly, we argue that typical duality groups such as SL(2,ℤ) have sign ambiguities in their actions on fermions, and propose that pertinent duality groups be extended by ℤ{sub 2}, to groups such as the metaplectic group. Specifically, we look at duality groups arising from mapping class groups of tori in M theory compactifications, T-duality, ten-dimensional type IIB S-duality, and (briefly) four-dimensional N=4 super Yang-Mills, and in each case, propose that the full duality group is a nontrivial ℤ{sub 2} extension of the duality group acting on bosonic degrees of freedom, to more accurately describe possible actions on fermions. We also walk through U-duality groups for toroidal compactifications to nine, eight, and seven dimensions, which enables us to perform cross-consistency tests of these proposals.
Majorana Fermion Induced Resonant Andreev Reflection
Law, K. T.; Lee, Patrick A.; Ng, T. K.
2009-01-01
We describe experimental signatures of Majorana fermion edge states, which form at the interface between a superconductor and the surface of a topological insulator. If a lead couples to the Majorana fermions through electron tunneling, the Majorana fermions induce \\textit{resonant} Andreev reflections from the lead to the grounded superconductor. The linear tunneling conductance is $0 $ ($2 e^2/h$) if there is an even (odd) number of vortices in the superconductor. Similar resonance occurs f...
Lattice quantum chromodynamics with approximately chiral fermions
Energy Technology Data Exchange (ETDEWEB)
Hierl, Dieter
2008-05-15
In this work we present Lattice QCD results obtained by approximately chiral fermions. We use the CI fermions in the quenched approximation to investigate the excited baryon spectrum and to search for the {theta}{sup +} pentaquark on the lattice. Furthermore we developed an algorithm for dynamical simulations using the FP action. Using FP fermions we calculate some LECs of chiral perturbation theory applying the epsilon expansion. (orig.)
Finite Temperature Qcd With Domain Wall Fermions
Fleming, G T
2001-01-01
Domain wall fermions are a new lattice fermion formulation which preserves the full chiral symmetry of the continuum at finite lattice spacing, up to terms exponentially small in an extra parameter. We discuss the main features of the formulation and its application to study of QCD with two light fermions of equal mass. We also present numerical studies of the two flavor QCD thermodynamics with aT = 1/4.
‘Going back home’: slave suicide in nineteenth century Cuba
Barcia, Manuel
2017-01-01
The issue of African slave suicides in Cuba was an always present one in the minds of slave traders, planters, and the colonial authorities. During the first half of the nineteenth century, discussions among the reasons behind this behavior included basically all sectors of the island’s society, including the main authorities. In this article, slave suicides are discussed both as a day-to-day action of resistance undertaken by the slaves, and as a social concern for those who had invested int...
Landing on the Beaches: the Functioning of the Brazilian Slave Trade After 1831
Directory of Open Access Journals (Sweden)
Marcus J. M. de Carvalho
2012-12-01
Full Text Available After 1831, the slave trade moved to natural harbors on the littoral, where it employed scores of people catering, healing, guarding the survivors, burying the dead. Smaller boats also helped the slave ships to reach the coast. The local population found new opportunities of employment and trade. Slave dealers had to buy or rent those lands, or associate themselves with their owners. The illegal slave trade would change the local economy and politics.
The Slave Ship Manuelita and the Story of a Yoruba Community, 1833-1834
Directory of Open Access Journals (Sweden)
Olatunji Ojo
Full Text Available Abstract: In 1833, a Cuban slave ship, the Manuelita, which embarked over 500 slaves in Lagos was seized and condemned by the Anglo-Spanish slave court. After the personal details of the Africans ‘liberated’ from the ship had been collected by court officials some of them were transported aboard the same ship to Trinidad as indentured workers and apprentices. Drawing on materials from the African Origins Database this paper investigates who these Africans were, where they came from, and what their stories highlight about slaving operations in the Lagos hinterland and the Americas in the age of abolition.
Is the Composite Fermion a Dirac Particle?
Directory of Open Access Journals (Sweden)
Dam Thanh Son
2015-09-01
Full Text Available We propose a particle-hole symmetric theory of the Fermi-liquid ground state of a half-filled Landau level. This theory should be applicable for a Dirac fermion in the magnetic field at charge neutrality, as well as for the ν=1/2 quantum Hall ground state of nonrelativistic fermions in the limit of negligible inter-Landau-level mixing. We argue that when particle-hole symmetry is exact, the composite fermion is a massless Dirac fermion, characterized by a Berry phase of π around the Fermi circle. We write down a tentative effective field theory of such a fermion and discuss the discrete symmetries, in particular, CP. The Dirac composite fermions interact through a gauge, but non-Chern-Simons, interaction. The particle-hole conjugate pair of Jain-sequence states at filling factors n/(2n+1 and (n+1/(2n+1, which in the conventional composite fermion picture corresponds to integer quantum Hall states with different filling factors, n and n+1, is now mapped to the same half-integer filling factor n+1/2 of the Dirac composite fermion. The Pfaffian and anti-Pfaffian states are interpreted as d-wave Bardeen-Cooper-Schrieffer paired states of the Dirac fermion with orbital angular momentum of opposite signs, while s-wave pairing would give rise to a particle-hole symmetric non-Abelian gapped phase. When particle-hole symmetry is not exact, the Dirac fermion has a CP-breaking mass. The conventional fermionic Chern-Simons theory is shown to emerge in the nonrelativistic limit of the massive theory.
Optical Lattice Gases of Interacting Fermions
2015-12-02
superfluid of fermionic atoms can arise from spin-singlet pairing between even and odd parity orbital bands [9]. This is again surprising because the...topology in momentum space, Weyl fermionic excitations, exotic surface states, and transport anomalies . The finite temperature phase diagram obtained
Phase separation in asymmetrical fermion superfluids.
Bedaque, Paulo F; Caldas, Heron; Rupak, Gautam
2003-12-12
Motivated by recent developments on cold atom traps and high density QCD we consider fermionic systems composed of two particle species with different densities. We argue that a mixed phase composed of normal and superfluid components is the energetically favored ground state. We suggest how this phase separation can be used as a probe of fermion superfluidity in atomic traps.
Superconducting gap anomaly in heavy fermion systems
Indian Academy of Sciences (India)
metal and undergoes a transition to the gap-less superconducting state. Keywords. Heavy fermion superconductor; Narrow band system; Valence fluctuation. PACS Nos 74.70.Tx; 71.28.+d; 75.30.Mb. 1. Introduction. The discovery of superconductivity in the so-called heavy fermion system CeCu2Si2,. UBe13, UPt3 [1] ...
On localization of Dirac fermions by disorder
Medvedyeva, Mariya Vyacheslavivna
2011-01-01
This thesis is devoted to the effects of disorder on two-dimensional systems of Dirac fermions. Disorder localizes the usual electron system governed by the Schroedinger equation. The influence of disorder on Dirac fermions is qualitevely different. We concentrate on a random mass term in the
Chiral gauge theories with domain wall fermions
Golterman, M.; Jansen, K.; Petcher, D.; Vink, J.
1993-01-01
We have investigated a proposal to construct chiral gauge theories on the lattice using domain wall fermions. The model contains two opposite chirality zeromodes, which live on two domain walls. We couple only one of them to a gauge field, but find that mirror fermions which also couple to the gauge field always seem to exist.
Power-counting theorem for staggered fermions
Giedt, J
2006-01-01
One of the assumptions that is used in Reisz's power-counting theorem does not hold for staggered fermions, as was pointed out long ago by Lüscher. Here, we generalize the power-counting theorem, and the methods of Reisz's proof, such that the dif culties posed by staggered fermions are overcome.
Boson--Fermion hybrid representation formulation, I
Energy Technology Data Exchange (ETDEWEB)
Wu, C.; Feng, D.H.
1981-08-01
A boson--fermion hybrid representation is presented. In this framework, a fermion system is described concurrently by the bosonic and the fermonic degrees of freedom. A fermion pair in this representation can be treated as a boson without violating the Pauli principle. Furthermore the ''bosonic interactions'' are shown to originate from the exchange processes of the fermions and can be calculated from the original fermion interactions. Both the formulation of the BFH representations for the even and odd nuclear systems are given. We find that the basic equation of the nuclear field theory (NFT) is just the usual Schroedinger equation in such a representation with the empirical NFT diagrammatic rules emerging naturally. This theory was numerically checked in the case of four nucleons moving in a single-j shell and the exactness of the theory was established.
Design, Implementation and Testing of Master Slave Robotic Surgical System
Directory of Open Access Journals (Sweden)
Syed Amjad Ali
2015-01-01
Full Text Available The autonomous manipulation of the medical robotics is needed to draw up a complete surgical plan in development. The autonomy of the robot comes from the fact that once the plan is drawn up off-line, it is the servo loops, and only these, that control the actions of the robot online, based on instantaneous control signals and measurements provided by the vision or force sensors. Using only these autonomous techniques in medical and surgical robotics remain relatively limited for two main reasons: Predicting complexity of the gestures, and human Safety. Therefore, Modern research in haptic force feedback in medical robotics is aimed to develop medical robots capable of performing remotely, what a surgeon does by himself. These medical robots are supposed to work exactly in the manner that a surgeon does in daily routine. In this paper the master slave tele-robotic system is designed and implemented with accuracy and stability by using 6DOF (Six Degree of Freedom haptic force feedback devices. The master slave control strategy, haptic devices integration, application software designing using Visual C++ and experimental setup are considered. Finally, results are presented the stability, accuracy and repeatability of the system
Accomodation and resistance: slaves in Brazil, 1780-1850
Directory of Open Access Journals (Sweden)
Dick GEARY
2009-03-01
Full Text Available RESUMEN: Este artículo examina las diferentes estrategias de supervivencia adoptadas por esclavos en Brasil entre 1780 y 1850. Plantea que las estrategias adoptadas variaron según la circunstancia y la oportunidad, y que éstas fueron complejas, implicando a veces simultáneamente los elementos tanto de la «aceptación» como de la «resistencia». Algunas de estas estrategias fueron individuales, pasando desde la compra de la libertad y del pleito, por la insubordinación menor hasta la lucha, el delito de incendio y el asesinato. Otras fueron colectivas (la formación de comunidades cimarronas y la rebelión, pero testigos del conflicto significativo entre los nacidos africanos y los esclavos criollos. ABSTRACT: This paper examines the various survival strategies adopted by slaves in Brazil between 1780 and 1850. It argues that the strategies adopted varied according to circumstance and opportunity, and that they were complex, involving sometimes simultaneously elements of both «accommodation» and «resistance». Some of these strategies were individual, ranging from the purchase of freedom and litigation, through petty insubordination to flight, arson and murder. Others were collective (the formation of maroon communities and rebellion but witnessed significant conflict between African-born and creole slaves.
Concept for a large master/slave-controlled robotic hand
Grissom, William A.; Abdallah, Mahmoud A.; White, Carl L.
1988-01-01
A strategy is presented for the design and construction of a large master/slave-controlled, five-finger robotic hand. Each of the five fingers will possess four independent axes each driven by a brushless DC servomotor and, thus, four degrees-of-freedom. It is proposed that commercially available components be utilized as much as possible to fabricate a working laboratory model of the device with an anticipated overall length of two-to-four feet (0.6 to 1.2 m). The fingers are to be designed so that proximity, tactile, or force/torque sensors can be imbedded in their structure. In order to provide for the simultaneous control of the twenty independent hand joints, a multilevel master/slave control strategy is proposed in which the operator wears a specially instrumented glove which produces control signals corresponding to the finger configurations and which is capable of conveying sensor feedback signals to the operator. Two dexterous hand master devices are currently commercially available for this application with both undergoing continuing development. A third approach to be investigated for the master control mode is the use of real-time image processing of a specially patterned master glove to provide the respective control signals for positioning the multiple finger joints.
Fermion Superfluidity And Confining Interactions
Galal, A A
2004-01-01
We study the pairing of Fermi systems with long-range, confining interparticle interactions. We solve the Cooper problem for a pair of fermions interacting via a regularized harmonic oscillator potential and determine the s-wave spectrum of bound states. Using a model of two interacting species of fermions, we calculate the ground state energy of the normal phase in the Hartree-Fock approximation and find that it is infrared (IR) divergent, due to a combination of the sharpness of the Fermi sea and the long-range nature of the interaction. We calculate the correlation energy in the normal phase using the random phase approximation (RPA) and demonstrate the cancellation of infrared divergences between the Hartree-Fock and RPA contributions. Introducing a variational wavefunction to study the superfluid phase, we solve the BCS equations using a Hartree-Fock-Bogoliubov (HFB) analysis to determine the wave-function, excitation gap, and other parameters of the superfluid phase. We show that the system crosses over...
Renormalization of minimally doubled fermions
Capitani, Stefano; Creutz, Michael; Weber, Johannes; Wittig, Hartmut
2010-09-01
We investigate the renormalization properties of minimally doubled fermions, at one loop in perturbation theory. Our study is based on the two particular realizations of Boriçi-Creutz and Karsten-Wilczek. A common feature of both formulations is the breaking of hyper-cubic symmetry, which requires that the lattice actions are supplemented by suitable counterterms. We show that three counterterms are required in each case and determine their coefficients to one loop in perturbation theory. For both actions we compute the vacuum polarization of the gluon. It is shown that no power divergences appear and that all contributions which arise from the breaking of Lorentz symmetry are cancelled by the counterterms. We also derive the conserved vector and axial-vector currents for Karsten-Wilczek fermions. Like in the case of the previously studied Boriçi-Creutz action, one obtains simple expressions, involving only nearest-neighbour sites. We suggest methods how to fix the coefficients of the counterterms non-perturbatively and discuss the implications of our findings for practical simulations.
The finite temperature phase transition in the lattice SU(2)-Higgs model
Farakos, K; Rummukainen, K; Shaposhnikov, Mikhail E
1994-01-01
We study the finite temperature transition of SU(2)-Higgs model with lattice Monte Carlo techniques. We use dimensional reduction to transform the original 4-dimensional SU(2)-gauge + fundamental Higgs theory to an effective 3-dimensional SU(2) + adjoint Higgs + fundamental Higgs model. The simulations were performed with Higgs masses of 35 and 80 GeV; in both cases we observe a stronger first order transition than the perturbation theory predicts, indicating that the dynamics of the transition strongly depend on non-perturbative effects.
Path integrals and coherent states of SU(2) and SU(1,1)
Inomata, Akira; Kuratsuji, Hiroshi
1992-01-01
The authors examine several topical subjects, commencing with a general introduction to path integrals in quantum mechanics and the group theoretical backgrounds for path integrals. Applications of harmonic analysis, polar coordinate formulation, various techniques and path integrals on SU(2) and SU(1, 1) are discussed. Soluble examples presented include particle-flux system, a pulsed oscillator, magnetic monopole, the Coulomb problem in curved space and others.The second part deals with the SU(2) coherent states and their applications. Construction and generalization of the SU(2) coherent sta
DeGout, Yasmin Y.
The differences between early African American narratives written by women and those written by men can be seen in a comparison of Harriet A. Jacobs's "Incidents in the Life of a Slave Girl, Written by Herself" and Frederick Douglass's "Narrative of the Life of Frederick Douglass, An American Slave." A comparison of these works…
Russia's Literary Genius Alexander Pushkin: The Great-Grandson of an African Slave.
Lounsbery, Anne
2000-01-01
Alexander Pushkin, Russia's most celebrated literary figure, descended from an African slave. On both parents' sides, he was related to Avram Petrovich Gannibal, who was born to an African prince and abducted to become a slave to a Russian diplomat. Pushkin chose to pride himself on both his aristocratic life and his African ancestry. (SM)
Western Theories and the Exploitation of West Africa since the Slave ...
African Journals Online (AJOL)
With the obsolescence of the slave trade in the late 18th century following the industrial revolution in Europe, new theories were propounded which painted the slave trade as evil and immoral. West African Kings and merchants who wanted to continue the trade were compelled to change to the 'legitimate' trade as defined ...
Sable Queens in Bondage: Reading, Independent Study, and Research on the American Slave Narrative.
Denniston, Dorothy L.
This paper examines the scope and historical significance of biographies and autobiographies of ex-slaves. The document focuses primarily on accounts of black women published from 1820-1860, but also discusses several narratives from colonial times. Exploits of famous women slaves including Harriet Tubman and Sojourner Truth are analyzed along…
'Slavery and the Slave Trade in Ikale, Yorubaland': A Rejoinder | Ojo ...
African Journals Online (AJOL)
Drawing on extensive primary documentation this review contends that while Ikale certainly played some roles in both slavery and the slave trade, its involvement remained very marginal at least for the period before 1850. Consequently, it reassesses the impact of slavery and the slave trade on Ikale political, social, ...
Research of the master-slave robot surgical system with the function of force feedback.
Shi, Yunyong; Zhou, Chaozheng; Xie, Le; Chen, Yongjun; Jiang, Jun; Zhang, Zhenfeng; Deng, Ze
2017-12-01
Surgical robots lack force feedback, which may lead to operation errors. In order to improve surgical outcomes, this research developed a new master-slave surgical robot, which was designed with an integrated force sensor. The new structure designed for the master-slave robot employs a force feedback mechanism. A six-dimensional force sensor was mounted on the tip of the slave robot's actuator. Sliding model control was adopted to control the slave robot. According to the movement of the master system manipulated by the surgeon, the slave's movement and the force feedback function were validated. The motion was completed, the standard deviation was calculated, and the force data were detected. Hence, force feedback was realized in the experiment. The surgical robot can help surgeons to complete trajectory motions with haptic sensation. Copyright © 2017 John Wiley & Sons, Ltd.
Sur l’adjectif possessif en slave et en tokharien
Directory of Open Access Journals (Sweden)
Milan Grošelj
1955-02-01
Full Text Available L’emploi de l’adj. poss. Remplaçant le gén. Poss. Est un des traits caractéristiques des langues slaves, cf. pour le detail Nahtigal, Slov. Jeziki 223 s. Le suffixe qui se prêtait à designer indiffémment un ou plusieurs possesseurs, a été supplanté par s+il s+agrissait d+un possesseur individual. C’était la consequence d’un changement dans la structure sociale. L’adj. poss. Est aussi bien représenté en tokh., voy. Sieg-Siegling-Schulze, Toch. Gramm. 41: “Das Tocharische liebt es, ähnlich wie die slavischen Sprachen, die Zugehörigkeit durch abgeleitete Adjektiva zu bezeichnen.” Dans les autres langues i.-e., l’emploi de l’adj. poss. Est limité aux patronymques et à quelques mots isolés comme scr. pitriyah, lat. Patrium. J. Wackernagel, Mélanges Pedersen (1908, 145 ss.; Vorl. II 68 ss. Était d’avis que, dans une période reculée, l’adj. poss. avait été aussi plus frequent en grec et en latin: le gén poss. ne serait que le prodoit d’un développement recent. Mais E. Löfstedt, Syntactica I (1928 83 ss. s’est senti oblige d’apporter des corrections essentielles aux vues de W. Selon Löfstedt, l’emploi de l’adj. poss. est, en grec et en latin, assez restraint. Il était d’un usage limité dans la langue homérique, influence en ceci par l’éolien, dans des cas comme on trouve aussi des adjectifs tires de noms communs, p. ex. Od. 18, 328. Ce n’était que dans le dialecte éolien que les patronymiques en c. à d. les adj. poss., étaient d’un usage courant et official, cf. éol. Ou même (Fraenkel PWRE XVI 1656, 8 ss.: Schwyzer, Griech. Gramm. II 177. En latin, ce sont les gentilices qui font pendant aux patronymiques éoliens: (Quintus Marcius était d’abord”(Q. fils de Marcus” avant de devenir un nom. Il est donc certain que l’emploi de l’adj. poss. n’est de règle qu’en slave et en tokh. Une question se pose, à savoir, si cette concordance est plus que fortuite. Des traits
Semiclassical approach to dynamics of interacting fermions
Davidson, Shainen M.; Sels, Dries; Polkovnikov, Anatoli
2017-09-01
Understanding the behaviour of interacting fermions is of fundamental interest in many fields ranging from condensed matter to high energy physics. Developing numerically efficient and accurate simulation methods is an indispensable part of this. Already in equilibrium, fermions are notoriously hard to handle due to the sign problem. Out of equilibrium, an important outstanding problem is the efficient numerical simulation of the dynamics of these systems. In this work we develop a new semiclassical phase-space approach (a.k.a. the truncated Wigner approximation) for simulating the dynamics of interacting fermions in arbitrary dimensions. As fermions are essentially non-classical objects, a phase-space is constructed out of all fermionic bilinears. Classical phase-space is thus comprised of highly non-local (hidden) variables representing these bilinears, and the cost of the method is that it scales quadratic rather than linear with system size. We demonstrate the strength of the method by comparing the results to the exact quantum dynamics of fermion expansion in the Hubbard model and quantum thermalization in the Sachdev-Ye-Kitaev (SYK) model for small systems, where the semiclassics nearly perfectly reproduces correct results. We furthermore analyse fermion expansion in a larger, intractable by exact methods, 2D Hubbard model, which is directly relevant to recent cold atom experiments.
Fermionic expressions for minimal model virasoro characters
Welsh, Trevor A
2005-01-01
Fermionic expressions for all minimal model Virasoro characters $\\chi^{p, p'}_{r, s}$ are stated and proved. Each such expression is a sum of terms of {\\em fundamental fermionic form} type. In most cases, all these terms are written down using certain trees which are constructed for $s$ and $r$ from the Takahashi lengths and truncated Takahashi lengths associated with the continued fraction of $p'/p$. In the remaining cases, in addition to such terms, the fermionic expression for $\\chi^{p, p'}_{r, s}$ contains a different character $\\chi^{\\hat p, \\hat p'}_{\\hat r,\\hat s}$, and is thus recursive in nature. Bosonic-fermionic $q$-series identities for all characters $\\chi^{p, p'}_{r, s}$ result from equating these fermionic expressions with known bosonic expressions. In the cases for which $p=2r$, $p=3r$, $p'=2s$ or $p'=3s$, Rogers-Ramanujan type identities result from equating these fermionic expressions with known product expressions for $\\chi^{p, p'}_{r, s}$. The fermionic expressions are proved by first obta...
Fermion algebra with Zp-graded parity: Representation and thermodynamics
Chung, Won Sang
2015-01-01
In this paper we discuss the fermion algebra with Zp-graded parity. We show that the fermion algebra with Z2-graded parity is equivalent to the paraboson algebra. For the fermion algebra with the Zp-parity, Fock representation is also discussed. Finally, we discuss the thermodynamics of a particle obeying the fermion algebra with Zp-parity.
SU(2) Flat Connection on Riemann Surface and Twisted Geometry with Cosmological Constant
Han, Muxin
2016-01-01
SU(2) flat connection on 2D Riemann surface is shown to relate to the generalized twisted geometry in 3D space with cosmological constant. Various flat connection quantities on Riemann surface are mapped to the geometrical quantities in discrete 3D space. We propose that the moduli space of SU(2) flat connections on Riemann surface generalizes the phase space of twisted geometry or Loop Quantum Gravity to include the cosmological constant.
Fermionic Zero Modes on Domain Walls
Stojkovic, Dejan
2000-01-01
We study fermionic zero modes in the domain wall background. The fermions have Dirac and left- and right-handed Majorana mass terms. The source of the Dirac mass term is the coupling to a scalar field $\\Phi$. The source of the Majorana mass terms could also be the coupling to a scalar field $\\Phi$ or a vacuum expectation value of some other field acquired in a phase transition well above the phase transition of the field $\\Phi$. We derive the fermionic equations of motion and find the necessa...
Instantons and Massless Fermions in Two Dimensions
Callan, C. G. Jr.; Dashen, R.; Gross, D. J.
1977-05-01
The role of instantons in the breakdown of chiral U(N) symmetry is studied in a two dimensional model. Chiral U(1) is always destroyed by the axial vector anomaly. For N = 2 chiral SU(N) is also spontaneously broken yielding massive fermions and three (decoupled) Goldstone bosons. For N greater than or equal to 3 the fermions remain massless. Realistic four dimensional theories are believed to behave in a similar way but the critical N above which the fermions cease to be massive is not known in four dimensions.
Majorana fermion induced resonant Andreev reflection.
Law, K T; Lee, Patrick A; Ng, T K
2009-12-04
We describe experimental signatures of Majorana fermion edge states, which form at the interface between a superconductor and the surface of a topological insulator. If a lead couples to the Majorana fermions through electron tunneling, the Majorana fermions induce resonant Andreev reflections from the lead to the grounded superconductor. The linear tunneling conductance is 0 (2e(2)/h) if there is an even (odd) number of vortices in the superconductor. Similar resonance occurs for tunneling into the zero mode in the vortex core. We also study the current and noise of a two-lead device.
Grassmann phase space theory for fermions
Energy Technology Data Exchange (ETDEWEB)
Dalton, Bryan J. [Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne, Victoria, 3122 (Australia); Jeffers, John [Department of Physics, University of Strathclyde, Glasgow, G4 ONG (United Kingdom); Barnett, Stephen M. [School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ (United Kingdom)
2017-06-15
A phase space theory for fermions has been developed using Grassmann phase space variables which can be used in numerical calculations for cold Fermi gases and for large fermion numbers. Numerical calculations are feasible because Grassmann stochastic variables at later times are related linearly to such variables at earlier times via c-number stochastic quantities. A Grassmann field version has been developed making large fermion number applications possible. Applications are shown for few mode and field theory cases. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
The fermion Monte Carlo revisited
Assaraf, Roland; Caffarel, Michel; Khelif, Anatole
2007-02-01
In this work we present a detailed study of the fermion Monte Carlo algorithm (FMC), a recently proposed stochastic method for calculating fermionic ground-state energies. A proof that the FMC method is an exact method is given. In this work the stability of the method is related to the difference between the lowest (bosonic-type) eigenvalue of the FMC diffusion operator and the exact Fermi energy. It is shown that within a FMC framework the lowest eigenvalue of the new diffusion operator is no longer the bosonic ground-state eigenvalue as in standard exact diffusion Monte Carlo (DMC) schemes but a modified value which is strictly greater. Accordingly, FMC can be viewed as an exact DMC method built from a correlated diffusion process having a reduced Bose-Fermi gap. As a consequence, the FMC method is more stable than any transient method (or nodal release-type approaches). It is shown that the most recent ingredient of the FMC approach (Kalos M H and Pederiva F 2000 Phys. Rev. Lett. 85 3547), namely the introduction of non-symmetric guiding functions, does not necessarily improve the stability of the algorithm. We argue that the stability observed with such guiding functions is in general a finite-size population effect disappearing for a very large population of walkers. The counterpart of this stability is a control population error which is different in nature from the standard diffusion Monte Carlo algorithm and which is at the origin of an uncontrolled approximation in FMC. We illustrate the various ideas presented in this work with calculations performed on a very simple model having only nine states but a full 'sign problem'. Already for this toy model it is clearly seen that FMC calculations are inherently uncontrolled.
Robust Master-Slave Synchronization of Neuronal Systems
Directory of Open Access Journals (Sweden)
Hector Puebla
2017-01-01
Full Text Available The desire to understand physiological mechanisms of neuronal systems has led to the introduction of engineering concepts to explain how the brain works. The synchronization of neurons is a central topic in understanding the behavior of living organisms in neurosciences and has been addressed using concepts from control engineering. We introduce a simple and reliable robust synchronization approach for neuronal systems. The proposed synchronization method is based on a master-slave configuration in conjunction with a coupling input enhanced with compensation of model uncertainties. Our approach has two nice features for the synchronization of neuronal systems: (i a simple structure that uses the minimum information and (ii good robustness properties against model uncertainties and noise. Two benchmark neuronal systems, Hodgkin-Huxley and Hindmarsh-Rose neurons, are used to illustrate our findings. The proposed synchronization approach is aimed at gaining insight into the effect of external electrical stimulation of nerve cells.
The African diaspora: mitochondrial DNA and the Atlantic slave trade.
Salas, Antonio; Richards, Martin; Lareu, María-Victoria; Scozzari, Rosaria; Coppa, Alfredo; Torroni, Antonio; Macaulay, Vincent; Carracedo, Angel
2004-03-01
Between the 15th and 19th centuries ad, the Atlantic slave trade resulted in the forced movement of approximately 13 million people from Africa, mainly to the Americas. Only approximately 11 million survived the passage, and many more died in the early years of captivity. We have studied 481 mitochondrial DNAs (mtDNAs) of recent African ancestry in the Americas and in Eurasia, in an attempt to trace them back to particular regions of Africa. Our results show that mtDNAs in America and Eurasia can, in many cases, be traced to broad geographical regions within Africa, largely in accordance with historical evidence, and raise the possibility that a greater resolution may be possible in the future. However, they also indicate that, at least for the moment, considerable caution is warranted when assessing claims to be able to trace the ancestry of particular lineages to a particular locality within modern-day Africa.
Many Seasons Gone: Memory, History, and the Atlantic Slave Trade
Directory of Open Access Journals (Sweden)
Ted Maris-Wolf
2009-07-01
Full Text Available [First paragraph] African Voices of the Atlantic Slave Trade: Beyond the Silence and the Shame. Anne C. Bailey. Boston: Beacon Press, 2005. 289 pp. (Cloth US $ 26.00 Lose Your Mother: A Journey along the Atlantic Slave Route. Saidiya Hartman. New York: Farrar, Straus and Giroux, 2007. xi + 270 pp. (Cloth US $ 25.00 In Two Thousand Seasons, the great Ghanaian novelist Ayi Kwei Armah describes the effects of centuries of European exploitation and violence in Africa and the alienation and death that separated Ghanaians in 1973 (when the book was published from those before them. “Pieces cut off from their whole are nothing but dead fragments,” he laments. “From the unending stream of our remembrance the harbingers of death break off meaningless fractions. Their carriers bring us this news of shards. Their message: behold this paltriness; this is all your history” (Armah 1973:2. It is this seeming paltriness, this history of meaningless fractions that Anne C. Bailey and Saidiya Hartman explore in their latest works, identifying and mending shards of memory and written and oral fragments into recognizable and meaningful forms. As with Armah in Two Thousand Seasons, for Bailey and Hartman, “the linking of those gone, ourselves here, those coming ... it is that remembrance that calls us” (Armah 1973:xiii. Both of them, haunted by remembrance and driven by a personal quest for reconciliation with the past and a scholarly desire for the truth, are unwilling to accept the past as passed, or to settle for the scattered silence that so often substitutes for the history of Africans and those of the diaspora.
Parallel ac-ac converters using master-slave control
Taufik
The objective of this study is to develop a parallel ac-ac converter that can be implemented as a means of connecting ac generators in parallel. The most important goal of the parallel converter in this study is to obtain equal current sharing performance among the paralleled generators such that an economically optimal solution for production cost of electricity can be accomplished. At the same time, voltage regulation and stability of the parallel system upon changes of different sizes and load types are to be maintained. Use of the available parallel converter method and voltage inversion technique leads to the formulation of a new solution technique for parallel operation of ac generators. The proposed parallel ac-ac converter involves Sinusoidal Pulse Width Modulation inverter combined with a control scheme called the Stationary Master-Slave control that uses voltage feedback loop and designates one generator unit as the master. The study involves numerous computer simulations to verify the feasibility of the parallel ac-ac converters. In doing so, as many as five models are considered including Current Control Current Source model, PI model, PI-PWM model, PI-PWM model with MOSFETs, and PI-PWM model with real MOSFET model. The results of the simulations show that the parallel ac-ac converter not only successfully provides the current sharing property among the paralleled units but also maintains system stability during changes in load demand. Further research work is suggested to address extensions to parallel ac-dc and dc-ac systems, hardware setup of at least two turbogenerators to test and verify the proposed approach, dynamic analysis to ensure system stability, and implementations of other types of Master-Slave control schemes to improve redundancy.
Energy Technology Data Exchange (ETDEWEB)
Gerhold, Philipp [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2009-12-15
We study a lattice Higgs-Yukawa model emulating the same Higgs-fermion coupling structure as in the Higgs sector of the electroweak Standard Model, in particular, obeying a Ginsparg- Wilson version of the underlying SU(2){sub L} x U(1){sub Y} symmetry, being a global symmetry here due to the neglection of gauge fields in this model. In this paper we present our results on the cutoffdependent upper Higgs boson mass bound at several selected values of the cutoff parameter {lambda}. (orig.)
The principle of the Fermionic projector
Finster, Felix
2006-01-01
The "principle of the fermionic projector" provides a new mathematical framework for the formulation of physical theories and is a promising approach for physics beyond the standard model. This book begins with a brief review of relativity, relativistic quantum mechanics, and classical gauge theories, emphasizing the basic physical concepts and mathematical foundations. The external field problem and Klein's paradox are discussed and then resolved by introducing the fermionic projector, a global object in space-time that generalizes the notion of the Dirac sea. At the mathematical core of the book is a precise definition of the fermionic projector and the use of methods of hyperbolic differential equations for detailed analysis. The fermionic projector makes it possible to formulate a new type of variational principle in space-time. The mathematical tools are developed for the analysis of the corresponding Euler-Lagrange equations. A particular variational principle is proposed that gives rise to an effective...
Rectification effect in Majorana fermion SQUID
Wang, Zhi; Liang, Qi-Feng; Hu, Xiao
2013-03-01
We investigated a SQUID structure formed by a spin-orbit coupling nanowire Josephson junction which contains Majorana fermions, and a conventional superconductor-insulator-superconductor junction, motivated by a recent experimental progress in realizing Majorana fermions in a heterostructure of a spin-orbit coupling nanowire and superconductor. It is shown that the critical current of the SQUID is different for two flowing directions, due to the unconventional current-phase relation of the nanowire junction. This asymmetric critical current serves as a simple and direct signature of the Majorana fermion existence. Since the asymmetric Josephson current forms a ratchet potential for the dynamics of superconducting phase, a rectification effect is expected when the SQUID is driven by an ac current. That is, a rectified dc voltage appears when a pure ac current is applied. This rectification effect is expected to be useful for probing the Majorana fermion dynamics.
Novel foamy origin for singlet fermion masses
Ellis, John; Mavromatos, Nick E.; Nanopoulos, Dimitri V.
2017-10-01
We show how masses for singlet fermions can be generated by interactions with a D-particle model of space-time foam inspired by brane theory. It has been shown previously by one of the authors (N. E. M.) that such interactions may generate dynamically small masses for charged fermions via the recoils of D-particle defects interacting with photons. In this work we consider the direct interactions of D-particle with uncharged singlet fermions such as right-handed neutrinos. Quantum fluctuations of the lattice of D-particles have massless vector (spin-one) excitations that are analogues of phonons. These mediate forces with the singlet fermions, generating large dynamical masses that may be communicated to light neutrinos via the seesaw mechanism.
Schroedinger equation for bosons and fermions
Energy Technology Data Exchange (ETDEWEB)
Kaniadakis, G. [Politecnico di Torino (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica della Materia, Unita del Politecnico di Torino, Turin (Italy)]|[Istituto Nazionale di Fisica Nucleare, Turin (Italy)
1995-10-09
We propose a non-linear Schroedinger equation describing the dynamics of bosons or fermions in an effective external force field. This equation is obtained by quantization of a stochastic Markovian process obeying a generalized exclusion principle. (orig.).
Fermions and the Gaussian effective potential
Energy Technology Data Exchange (ETDEWEB)
Stevenson, P.M.; Hajj, G.A.; Reed, J.F.
1986-11-15
The effect of fermions on the Gaussian effective potential is studied in a variety of fermion-scalar models in 2, 3, and 4 dimensions. Both gphipsi-barpsi and gphi/sup 2/psi-barpsi couplings are considered. Stability requires the bare g to be infinitesimal; g/sub B/ /sup 2/ = G/sup 2//I/sub 0/ with I/sub 0/ a divergent integral. This contrasts with large-N studies in which g/sub B/ remains finite. The presence of fermions encourages spontaneous symmetry breaking, and in 3+1 dimensions the fermions destabilize the already ''precarious'' phi/sup 4/ theory.
State of the art in design and control of master-slave manipulators
Energy Technology Data Exchange (ETDEWEB)
Kim, Ki Ho; Kim, Seung Ho; Kim, Byung Soo; Kim, Chang Hoi; Jung, Seung Ho; Kwang, Suk Yeoung; Seo, Yong Chil; Lee, Young Kwang
1998-03-01
The use of remotely operated robots and other mechanical devices as replacements of human workers in hazardous environments is a growing field of research. In particular, master-slave manipulators have been extensively used in the nuclear industries governed by the ALARA principle for more than four decades. There, however, are still few successful implementations of complex and high degree-of-freedom systems. The master manipulator is an input device which interfaces with the human operator on one side and with the slave manipulator on the other. Bilateral force-reflecting control plays a key supporting role in successful dexterous manipulation of the master-slave manipulators. Great increase in performance of the master-slave manipulator system can be achieved through good design of mechanical hardware and proper implementation of the embedded control strategies. This report presents some of design issues relevant to designers of the master manipulator as man-machine interface device in the master-slave manipulator system. Significant design parameters for both the replica and universal master manipulators are evaluated. In addition, the report describes the various control schemes of the bilateral force-reflecting master-slave manipulators, discusses the analysis and synthesis of the control loop between the master and slave manipulators, and examines the necessary position and force information on both sides. (author). 80 refs., 2 tabs., 15 figs
Nonequilibrium fermion production in quantum field theory
Energy Technology Data Exchange (ETDEWEB)
Pruschke, Jens
2010-06-16
The creation of matter in the early universe or in relativistic heavy-ion collisions is inevitable connected to nonequilibrium physics. One of the key challenges is the explanation of the corresponding thermalization process following nonequilibrium instabilities. The role of fermionic quantum fields in such scenarios is discussed in the literature by using approximations of field theories which neglect important quantum corrections. This thesis goes beyond such approximations. A quantum field theory where scalar bosons interact with Dirac fermions via a Yukawa coupling is analyzed in the 2PI effective action formalism. The chosen approximation allows for a correct description of the dynamics including nonequilibrium instabilities. In particular, fermion-boson loop corrections allow to study the interaction of fermions with large boson fluctuations. The applied initial conditions generate nonequilibrium instabilities like parametric resonance or spinodal instabilities. The equations of motion for correlation functions are solved numerically and major characteristics of the fermion dynamics are described by analytical solutions. New mechanisms for the production of fermions are found. Simulations in the case of spinodal instability show that unstable boson fluctuations induce exponentially growing fermion modes with approximately the same growth rate. If the unstable regime lasts long enough a thermalization of the infrared part of the fermion occupation number occurs on time scales much shorter than the time scale on which bosonic quantum fields thermalize. Fermions acquire an excess of occupation in the ultraviolet regime compared to a Fermi-Dirac statistic characterized by a power-law with exponent two. The fermion production mechanism via parametric resonance is found to be most efficient after the instability ends. Quantum corrections then provide a very efficient particle creation mechanism which is interpreted as an amplification of decay processes. The ratio
Projecting Fermion Pair Condensates into Molecular Condensates
Diener, Roberto B.; Ho, Tin-Lun
2004-01-01
We offer strong evidence that the recent observations by M. Greiner, C. Regal, and D. Jin and by MIT group are signatures of a fermion superfluid in the strongly interacting regime made up of large fermion pairs. Our conclusions are based on calculations using crossover theory for different potentials including those with the characteristics of two-channel models. Our results demonstrate clearly universality near resonance. The $T_{c}$ predicted by crossover theory is a perfect match with the...
Superfluid response in heavy fermion superconductors
Zhong, Yin; Zhang, Lan; Shao, Can; Luo, Hong-Gang
2017-10-01
Motivated by a recent London penetration depth measurement [H. Kim, et al., Phys. Rev. Lett. 114, 027003 (2015)] and novel composite pairing scenario [O. Erten, R. Flint, and P. Coleman, Phys. Rev. Lett. 114, 027002 (2015)] of the Yb-doped heavy fermion superconductor CeCoIn5, we revisit the issue of superfluid response in the microscopic heavy fermion lattice model. However, from the literature, an explicit expression for the superfluid response function in heavy fermion superconductors is rare. In this paper, we investigate the superfluid density response function in the celebrated Kondo-Heisenberg model. To be specific, we derive the corresponding formalism from an effective fermionic large- N mean-field pairing Hamiltonian whose pairing interaction is assumed to originate from the effective local antiferromagnetic exchange interaction. Interestingly, we find that the physically correct, temperature-dependent superfluid density formula can only be obtained if the external electromagnetic field is directly coupled to the heavy fermion quasi-particle rather than the bare conduction electron or local moment. Such a unique feature emphasizes the key role of the Kondo-screening-renormalized heavy quasi-particle for low-temperature/energy thermodynamics and transport behaviors. As an important application, the theoretical result is compared to an experimental measurement in heavy fermion superconductors CeCoIn5 and Yb-doped Ce1- x Yb x CoIn5 with fairly good agreement and the transition of the pairing symmetry in the latter material is explained as a simple doping effect. In addition, the requisite formalism for the commonly encountered nonmagnetic impurity and non-local electrodynamic effect are developed. Inspired by the success in explaining classic 115-series heavy fermion superconductors, we expect the present theory will be applied to understand other heavy fermion superconductors such as CeCu2Si2 and more generic multi-band superconductors.
NLO Antenna Subtraction with Massive Fermions
Ridder, A. Gehrmann-De; Ritzmann, M.
2009-01-01
We present an extension of the antenna subtraction formalism at NLO to include massive final state fermions. The basic ingredients to the subtraction terms, the NLO massive final-final antenna functions are derived and integrated over the corresponding factorised phase space. Those antenna functions account for all soft, collinear and quasi-collinear limits of the QCD matrix elements involving massive fermions in the final state.
The minimal fermionic model of electroweak baryogenesis
Egana-Ugrinovic, Daniel
2017-12-01
We present the minimal model of electroweak baryogenesis induced by fermions. The model consists of an extension of the Standard Model with one electroweak singlet fermion and one pair of vector like doublet fermions with renormalizable couplings to the Higgs. A strong first order phase transition is radiatively induced by the singlet-doublet fermions, while the origin of the baryon asymmetry is due to asymmetric reflection of the same set of fermions on the expanding electroweak bubble wall. The singlet-doublet fermions are stabilized at the electroweak scale by chiral symmetries and the Higgs potential is stabilized by threshold corrections coming from a multi-TeV ultraviolet completion which does not play any significant role in the phase transition. We work in terms of background symmetry invariants and perform an analytic semiclassical calculation of the baryon asymmetry, showing that the model may effectively generate the observed baryon asymmetry for percent level values of the unique invariant CP violating phase of the singlet-doublet sector. We include a detailed study of electron electric dipole moment and electroweak precision limits, and for one typical benchmark scenario, we also recast existing collider constraints, showing that the model is consistent with all current experimental data. We point out that fermion induced electroweak baryogenesis has irreducible phenomenology at the 13 TeV LHC since the new fermions must be at the electroweak scale, have electroweak quantum numbers and couple strongly to the Higgs. The most promising searches involve topologies with multiple leptons and missing energy in the final state.
Plasma oscillations of edge Dirac fermions
Volkov, V. A.; Zagorodnev, I. V.
2013-06-01
The dispersion law of one-dimensional plasmons in a quasi-one-dimensional system of massless Dirac fermions has been calculated. Two model two-dimensional systems where bands of edge states filled with such Dirac fermions appear at the edge have been considered. Edge states in the first system, topological insulator, are due to topological reasons. Edge states in the second system, system of massive Dirac fermions, have Tamm origin. It has been shown that the dispersion laws of plasmons in both systems in the long-wavelength limit differ only in the definition of the parameters (velocity and localization depth of Dirac fermions). The frequency of plasmons is formally quantum (ω ∝ ħ -1/2) and, in the case of the Coulomb interaction between electrons, depends slightly on the Fermi level E F. The dependence on E F is stronger in the case of short-range interaction. The quantum features of oscillations of massless one-dimensional Dirac fermions are removed by introducing the mass of Dirac fermions at the Fermi level and their density. Correspondence to the dispersion law of classical one-dimensional plasma oscillations in a narrow stripe of "Schrödinger" electrons has been revealed.
Fermion-induced quantum critical points.
Li, Zi-Xiang; Jiang, Yi-Fan; Jian, Shao-Kai; Yao, Hong
2017-08-22
A unified theory of quantum critical points beyond the conventional Landau-Ginzburg-Wilson paradigm remains unknown. According to Landau cubic criterion, phase transitions should be first-order when cubic terms of order parameters are allowed by symmetry in the Landau-Ginzburg free energy. Here, from renormalization group analysis, we show that second-order quantum phase transitions can occur at such putatively first-order transitions in interacting two-dimensional Dirac semimetals. As such type of Landau-forbidden quantum critical points are induced by gapless fermions, we call them fermion-induced quantum critical points. We further introduce a microscopic model of SU(N) fermions on the honeycomb lattice featuring a transition between Dirac semimetals and Kekule valence bond solids. Remarkably, our large-scale sign-problem-free Majorana quantum Monte Carlo simulations show convincing evidences of a fermion-induced quantum critical points for N = 2, 3, 4, 5 and 6, consistent with the renormalization group analysis. We finally discuss possible experimental realizations of the fermion-induced quantum critical points in graphene and graphene-like materials.Quantum phase transitions are governed by Landau-Ginzburg theory and the exceptions are rare. Here, Li et al. propose a type of Landau-forbidden quantum critical points induced by gapless fermions in two-dimensional Dirac semimetals.
Fermionic topological quantum states as tensor networks
Wille, C.; Buerschaper, O.; Eisert, J.
2017-06-01
Tensor network states, and in particular projected entangled pair states, play an important role in the description of strongly correlated quantum lattice systems. They do not only serve as variational states in numerical simulation methods, but also provide a framework for classifying phases of quantum matter and capture notions of topological order in a stringent and rigorous language. The rapid development in this field for spin models and bosonic systems has not yet been mirrored by an analogous development for fermionic models. In this work, we introduce a tensor network formalism capable of capturing notions of topological order for quantum systems with fermionic components. At the heart of the formalism are axioms of fermionic matrix-product operator injectivity, stable under concatenation. Building upon that, we formulate a Grassmann number tensor network ansatz for the ground state of fermionic twisted quantum double models. A specific focus is put on the paradigmatic example of the fermionic toric code. This work shows that the program of describing topologically ordered systems using tensor networks carries over to fermionic models.
[The demographic characteristics of slaves in Sao Paulo, 1777-1829].
Luna, F V
1992-01-01
"The introduction and development of sugar and coffee production in Sao Paulo [Brazil] led to deep changes in its populational structure. The large number of slaves who entered the province, mainly adult men, destroyed the population's relative balance, both in terms of sex and age structures. The study, based on manuscripts known as ¿Macos de Populacao' which belong to the Arquivo do Estado de Sao Paulo, covers twenty-five different communities in Sao Paulo, in the years 1777, 1804 and 1829. The demographic characteristics of the slaves and their relation with economic variables were analysed.... Special attention was given to the slaves' marriage and their reproductive capacity." (EXCERPT)
Bifurcations in dissipative fermionic dynamics
Napolitani, Paolo; Colonna, Maria; Di Prima, Mariangela
2014-05-01
The Boltzmann-Langevin One-Body model (BLOB), is a novel one-body transport approach, based on the solution of the Boltzmann-Langevin equation in three dimensions; it is used to handle large-amplitude phase-space fluctuations and has a broad applicability for dissipative fermionic dynamics. We study the occurrence of bifurcations in the dynamical trajectories describing heavy-ion collisions at Fermi energies. The model, applied to dilute systems formed in such collisions, reveals to be closer to the observation than previous attempts to include a Langevin term in Boltzmann theories. The onset of bifurcations and bimodal behaviour in dynamical trajectories, determines the fragment-formation mechanism. In particular, in the proximity of a threshold, fluctuations between two energetically favourable mechanisms stand out, so that when evolving from the same entrance channel, a variety of exit channels is accessible. This description gives quantitative indications about two threshold situations which characterise heavy-ion collisions at Fermi energies. First, the fusion-to-multifragmentation threshold in central collisions, where the system either reverts to a compact shape, or splits into several pieces of similar sizes. Second, the transition from binary mechanisms to neck fragmentation (in general, ternary channels), in peripheral collisions.
Iterants, Fermions and Majorana Operators
Kauffman, Louis H.
Beginning with an elementary, oscillatory discrete dynamical system associated with the square root of minus one, we study both the foundations of mathematics and physics. Position and momentum do not commute in our discrete physics. Their commutator is related to the diffusion constant for a Brownian process and to the Heisenberg commutator in quantum mechanics. We take John Wheeler's idea of It from Bit as an essential clue and we rework the structure of that bit to a logical particle that is its own anti-particle, a logical Marjorana particle. This is our key example of the amphibian nature of mathematics and the external world. We show how the dynamical system for the square root of minus one is essentially the dynamics of a distinction whose self-reference leads to both the fusion algebra and the operator algebra for the Majorana Fermion. In the course of this, we develop an iterant algebra that supports all of matrix algebra and we end the essay with a discussion of the Dirac equation based on these principles.
Majorana fermions in semiconductor nanowires
Stanescu, Tudor D.; Lutchyn, Roman M.; Das Sarma, S.
2011-10-01
We study multiband semiconducting nanowires proximity coupled with an s-wave superconductor and calculate the topological phase diagram as a function of the chemical potential and magnetic field. The nontrivial topological state corresponds to a superconducting phase supporting an odd number of pairs of Majorana modes localized at the ends of the wire, whereas the nontopological state corresponds to a superconducting phase with no Majoranas or with an even number of pairs of Majorana modes. Our key finding is that multiband occupancy not only lifts the stringent constraint of one-dimensionality, but also allows having higher carrier density in the nanowire. Consequently, multiband nanowires are better suited for stabilizing the topological superconducting phase and for observing the Majorana physics. We present a detailed study of the parameter space for multiband semiconductor nanowires focusing on understanding the key experimental conditions required for the realization and detection of Majorana fermions in solid-state systems. We include various sources of disorder and characterize their effects on the stability of the topological phase. Finally, we calculate the local density of states as well as the differential tunneling conductance as functions of external parameters and predict the experimental signatures that would establish the existence of emergent Majorana zero-energy modes in solid-state systems.
Heat, sex, and sugar: pregnancy and childbearing in the slave quarters.
Follett, Richard
2004-10-01
This article examines the dynamics of slave fecundity in the antebellum South and analyzes the relationship between the planters' labor requirements and pregnancy on large sugar estates in nineteenth-century Louisiana. In contrast to the cotton states, where the slave population grew, bondspeople in Louisiana's sugar world experienced natural population decrease. This derived in part from imbalanced sex ratios, but as this article explores, it also occurred because of the punishing nature of sugar production that taxed slave women in distinct ways over the entire year. As this article shows, conceptions peaked during the annual harvest season but collapsed at other times because of nutritional stress, overwork, heat, and exhaustion. Addressing the seasonality of slave childbirths, the article posits that workload combined with climatic, ecological, hormonal, nutritional, and lactation factors ultimately shaped the reproductive ecology of American slavery.
Indians, slaves, and freedmen in the the Pee Dee region of South Carolina
US Fish and Wildlife Service, Department of the Interior — This record is an unpublished report about the history of Native Americans, slaves and freedmen in the Pee Dee. It is a historical report but intended for use as...
Evolution of Hall resistivity and spectral function with doping in the SU(2) theory of cuprates
Morice, C.; Montiel, X.; Pépin, C.
2017-10-01
Recent transport experiments in the cuprate superconductors linked the opening of the pseudogap to a change in electronic dispersion [S. Badoux et al., Nature (London) 531, 210 (2015), 10.1038/nature16983]. Transport measurements showed that the carrier density sharply changes from x to 1 +x at the pseudogap critical doping, in accordance with the change from Fermi arcs at low doping to a large hole Fermi surface at high doping. The SU(2) theory of cuprates shows that short-range antiferromagnetic correlations cause the arising of both charge and superconducting orders, which are related by an SU(2) symmetry. The fluctuations associated with this symmetry form a pseudogap phase. Here we derive the renormalized electronic propagator under the SU(2) dome, and calculate the spectral functions and transport quantities of the renormalized bands. We show that their evolution with doping matches both spectral and transport measurements.
Bodies of Knowledge: The Influence of Slaves on the Antebellum Medical Community
Mitchell, Sarah
1997-01-01
The influence of slaves on the south is well documented in areas such as agriculture, music, diet, religion and language. This thesis extends the list to include medicine. It also suggests that the importance of cultural transfer to America from places other than Europe has been overlooked in the history of medicine. The medical influence of slaves took the form of botanical remedies, many of them with an African origin, and were disseminated through the tr...
On the SU(2 vertical stroke 1) WZNW model and its statistical mechanics applications
Energy Technology Data Exchange (ETDEWEB)
Saleur, H. [CEA Centre d' Etudes de Saclay, 91 - Gif-sur-Yvette (France). Service de Physique Theorique]|[University of Southern California, Los Angeles, CA (United States). Dept. of Physics; Schomerus, V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2006-11-15
Motivated by a careful analysis of the Laplacian on the supergroup SU(2 vertical stroke 1) we formulate a proposal for the state space of the SU(2 vertical stroke 1) WZNW model. We then use properties of sl(2 vertical stroke 1) characters to compute the partition function of the theory. In the special case of level k=1 the latter is found to agree with the properly regularized partition function for the continuum limit of the integrable sl(2 vertical stroke 1)3- anti 3 super-spin chain. Some general conclusions applicable to other WZNW models (in particular the case k=-1/2) are also drawn. (orig.)
A Master-Slave Haptic System for Neurosurgery
Directory of Open Access Journals (Sweden)
Vanni Zanotto
2011-01-01
Full Text Available In recent years, new surgical tools have been designed to improve treatment results and lower patient trauma. Nevertheless, the dexterity and accuracy required for the positioning of new tools are often unreachable, if surgeons are not assisted by suitable systems. Significant advantages are derived from the introduction of computer and robot technologies. For that reason, the interaction between robotic systems and surgeons today is producing new interest worldwide both in medical and engineering fields. In particular, medical robotics has found fruitful ground in neurosurgical applications, since the high functional density of the central nervous system requires strict accuracy constraints on tool positioning. As a matter of fact, the major benefits of robots, such as precision, accuracy and repeatability, make them ideal as neurosurgeons’ assistants. This paper presents a master-slave haptic robotic system for minimally invasive neurosurgery, which can aid surgeons in performing safer and more accurate stereotactic neurosurgical treatments. The design of the proposed system is based on LANS (Linear Actuator for NeuroSurgery, which has been developed by our Research Group. Experimental test aimed at showing the added value of the DAANS system over its predecessor, the effectiveness of conformational caps and of the added rotational degree of freedom are scheduled for the upcoming months.
Link fermions in Euclidean lattice gauge theory
Energy Technology Data Exchange (ETDEWEB)
Brower, R.; Giles, R.; Maturana, G.
1984-02-15
The representation of the Wilson lattice fermion propagator as a sum over classical particle trajectories is discussed. A simple generalization of this path sum leads to an extended set of fermion theories characterized by one (or more) additional parameters. Such theories are nonlocal when written in terms of the usual four-component Dirac field. They are more naturally characterized by a local action functional whose degrees of freedom are those of a set of two-component Fermi fields defined on directed links of the lattice. Such lattice fields correspond to the direct product of a four-vector and Dirac spinor. For a suitable choice of parameters, the extended fermion theory offers a precocious approach to the continuum dispersion relation as the lattice spacing goes to zero and is therefore of interest for numerical studies of QCD.
Dark Energy from Interacting Dark Fermions
Goldman, Terrence; McKellar, Bruce; Alsing, Paul; Stephenson, Gerard
2010-11-01
Physics is rife with interacting systems that exhibit negative pressure: atomic nuclei are very well known examples. We examine the range of parameters, for neutral fermions interacting only by exchange of an extraordinarily light scalar particle, that produce a negative pressure on the scale of the Universe over time periods where Dark Energy is or may be relevant. Of known or expected neutral Majorana fermions, active neutrinos can be ruled out but sterile neutrinos would work, as well as the LSP, to describe the recent observations of Dark Energy effects. After a phase change required by the instability responsible for the negative pressure, the resulting clouds of neutral fermions will contribute to Dark Matter. Nothing requires that this can only happen once.
No fermion doubling in quantum geometry
Energy Technology Data Exchange (ETDEWEB)
Gambini, Rodolfo [Instituto de Física, Facultad de Ciencias, Iguá 4225, esq. Mataojo, 11400 Montevideo (Uruguay); Pullin, Jorge, E-mail: pullin@lsu.edu [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States)
2015-10-07
In loop quantum gravity the discrete nature of quantum geometry acts as a natural regulator for matter theories. Studies of quantum field theory in quantum space–times in spherical symmetry in the canonical approach have shown that the main effect of the quantum geometry is to discretize the equations of matter fields. This raises the possibility that in the case of fermion fields one could confront the usual fermion doubling problem that arises in lattice gauge theories. We suggest, again based on recent results on spherical symmetry, that since the background space–times will generically involve superpositions of states associated with different discretizations the phenomenon may not arise. This opens a possibility of incorporating chiral fermions in the framework of loop quantum gravity.
Thermodynamics of SU(2) quantum Yang-Mills theory and CMB anomalies
Hofmann, Ralf
2013-01-01
A brief review of effective SU(2) Yang-Mills thermodynamics in the deconfining phase is given, including the construction of the thermal ground-state estimate in terms of an inert, adjoint scalar field $\\phi$, based on non-propagating (anti)selfdual field configurations of topological charge unity. We explain why the screening physics of an SU(2) photon is subject to an electric-magnetically dual interpretation. Next, we elucidate how a low-frequency excess of line temperature in the Cosmic Microwave Background (CMB) determines the value of the critical temperature of the deconfining-preconfining phase transition of an SU(2) Yang-Mills theory postulated to describe photon propagation, and we describe how, starting at a redshift of about unity, SU(2) photons collectively work 3D temperature depressions into the CMB. Upon projection along a line of sight, a given depression influences the present CMB sky in a cosmologically local way, possibly explaining the large-angle anomalies confirmed recently by the Planc...
SU(2)$_{\\tiny\\mbox{CMB}}$ at high redshifts and the value of $H_0$
Hahn, Steffen
2016-01-01
We investigate a high-$z$ cosmological model to compute the co-moving sound horizon $r_s$ at baryon freeze-out following hydrogen recombination. This model assumes a replacement of the conventional CMB photon gas by SU(2) Yang-Mills thermodynamics, three flavors of massless neutrinos ($N_\
Supersymmetric solutions of SU(2-Fayet–Iliopoulos-gauged N=2, d=4 supergravity
Directory of Open Access Journals (Sweden)
Tomás Ortín
2017-03-01
Full Text Available We explore the construction of supersymmetric solutions of theories of N=2,d=4 supergravity with a SU(2 gauging and SU(2 Fayet–Iliopoulos terms. In these theories an SU(2 isometry subgroup of the Special-Kähler manifold is gauged together with a SU(2 R-symmetry subgroup. We construct several solutions of the CP‾3 quadratic model directly in four dimensions and of the ST[2,6] model by dimensional reduction of the solutions found by Cariglia and Mac Conamhna in N=(1,0,d=6 supergravity with the same kind of gauging. In the CP‾3 model, we construct an AdS2×S2 solution which is only 1/8 BPS and an R×H3 solutions that also preserves 1 of the 8 possible supersymmetries. We show how to use dimensional reduction as in the ungauged case to obtain Rn×Sm and also AdSn×Sm-type solutions (with different radii in 5- and 4-dimensions from the 6-dimensional AdS3×S3 solution.
Light Asymmetric Dark Matter on the Lattice: SU(2) Technicolor with Two Fundamental Flavors
DEFF Research Database (Denmark)
Lewis, Randy; Pica, Claudio; Sannino, Francesco
2012-01-01
The SU(2) gauge theory with two massless Dirac flavors constitutes the building block of several models of Technicolor. Furthermore it has also been used as a template for the construction of a natural light asymmetric, or mixed type, dark matter candidate. We use explicit lattice simulations to ...
On 2D and 3D solitons in SU(2) gluo-dynamics
Energy Technology Data Exchange (ETDEWEB)
Bogolubskaya, Alla; Bogolubsky, Igor [Joint Institute for Nuclear Research - JINR, Joliot-Curie st., 6, Moskovskaya obl., 141980, Dubna (Russian Federation)
2010-07-01
We plan to indicate the possibility of soliton existence in 2D and 3D SU(2) gluo-dynamics. Hamiltonians in terms of radial functions will be presented. Localized in space field distributions which provide local minima to these Hamiltonians are studied. Their physical implications are discussed. (author)
Anatomy of isolated monopole in Abelian projection od SU(2) lattice gauge theory
Belavin, V A; Veselov, A I
2001-01-01
The structure of the isolated static monopolies in the maximum Abelian projection of the SU(2) gluodynamics on the lattice studied. The standard parametrization of the coupling matrix was used by determining the maximum Abelian projection of the R functional maximization relative to all scale transformations. The monopole radius R approx = 0.06 fm is evaluated
Weinberg Angle Derivation from Discrete Subgroups of SU(2 and All That
Directory of Open Access Journals (Sweden)
Potter F.
2015-01-01
Full Text Available The Weinberg angle W of the Standard Model of leptons and quarks is derived from specific discrete (i.e., finite subgroups of the electroweak local gauge group SU(2 L U(1 Y . In addition, the cancellation of the triangle anomaly is achieved even when there are four quark families and three lepton families!
An SU(2) symmetry of the one-dimensional spin-1 XY model
Kitazawa, A; Nomura, K
2003-01-01
We show that the one-dimensional spin-1 XY model has an additional SU(2) symmetry for the open boundary condition and for an artificial one. We can explain some degeneracies of excitation states which were reported in previous numerical studies. (letter to the editor)
Fermion-fermion scattering in quantum field theory with superconducting circuits.
García-Álvarez, L; Casanova, J; Mezzacapo, A; Egusquiza, I L; Lamata, L; Romero, G; Solano, E
2015-02-20
We propose an analog-digital quantum simulation of fermion-fermion scattering mediated by a continuum of bosonic modes within a circuit quantum electrodynamics scenario. This quantum technology naturally provides strong coupling of superconducting qubits with a continuum of electromagnetic modes in an open transmission line. In this way, we propose qubits to efficiently simulate fermionic modes via digital techniques, while we consider the continuum complexity of an open transmission line to simulate the continuum complexity of bosonic modes in quantum field theories. Therefore, we believe that the complexity-simulating-complexity concept should become a leading paradigm in any effort towards scalable quantum simulations.
Towards satisfactory scattering amplitudes for dual fermions
Olive, D
1973-01-01
The authors find the modified Lorentz invariant propagator which, when used on Neveu-Schwarz meson lines joining fermion lines, guarantees the coupling of just the ghost-free transverse spectrum of meson states. The modification is necessary to take account of the new form of reflected Ward identity valid for such lines. Thus they can write down dual amplitudes for processes involving four external fermions which possess a high degree of inner consistency, no-ghost theorems and Lorentz invariance, but they have not yet been able to evaluate them. (13 refs).
On the integrable gravity coupled to fermions
Belinski, Vladimir A
2016-01-01
In the present paper we indicate an extension of the pure gravity inverse scattering integration technique (developed in [2]) to the case when fermions are present. With this extension the integrability of the maximal supergravity $N=16$ in two space-time dimensions constructed in [1] is revisited. In addition to the results of the article [1] the spectral linear problem proposed in the present paper covers also the Dirac-like fermionic equations of motion and is free of the second order poles with respect to the spectral parameter. The procedure of constructing the exact super-solitonic solutions is outlined.
A Search for Excited Fermions at HERA
Adloff, C.; Andrieu, B.; Arkadov, V.; Astvatsatourov, A.; Ayyaz, I.; Babaev, A.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Bate, P.; Beglarian, A.; Behnke, O.; Beier, C.; Belousov, A.; Benisch, T.; Berger, Christoph; Bernardi, G.; Berndt, T.; Bizot, J.C.; Borras, K.; Boudry, V.; Braunschweig, W.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruckner, W.; Bruel, P.; Bruncko, D.; Burger, J.; Busser, F.W.; Bunyatyan, A.; Burkhardt, H.; Burrage, A.; Buschhorn, G.; Campbell, A.J.; Cao, Jun; Carli, T.; Caron, S.; Chabert, E.; Clarke, D.; Clerbaux, B.; Collard, C.; Contreras, J.G.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dixon, P.; Dodonov, V.; Dowell, J.D.; Droutskoi, A.; Duprel, C.; Eckerlin, Guenter; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Foster, J.M.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, Joerg; Gerhards, R.; Ghazaryan, Samvel; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goodwin, C.; Grab, C.; Grassler, H.; Greenshaw, T.; Grindhammer, Guenter; Hadig, T.; Haidt, D.; Hajduk, L.; Haynes, W.J.; Heinemann, B.; Heinzelmann, G.; Henderson, R.C.W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hilgers, M.; Hiller, K.H.; Hladky, J.; Hoting, P.; Hoffmann, D.; Hoprich, W.; Horisberger, R.; Hurling, S.; Ibbotson, M.; Issever, C .; Jacquet, M.; Jaffre, M.; Janauschek, L.; Jansen, D.M.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jones, M.A.S.; Jung, H.; Kastli, H.K.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Kaufmann, O.; Kausch, M.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kermiche, S.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Knies, G.; Koblitz, B.; Kolya, S.D.; Korbel, V.; Kostka, P.; Kotelnikov, S.K.; Krasny, M.W.; Krehbiel, H.; Kroseberg, J.; Kruger, K.; Kupper, A.; Kuhr, T.; Kurca, T.; Kutuev, R.; Lachnit, W.; Lahmann, R.; Lamb, D.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Lebailly, E.; Lebedev, A.; Leissner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindstroem, M.; Lobodzinska, E.; Lobodzinski, B.; Loktionova, N.; Lubimov, V.; Luders, S.; Luke, D.; Lytkin, L.; Magnussen, N.; Mahlke-Kruger, H.; Malden, N.; Malinovski, E.; Malinovski, I.; Maracek, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.U.; Martyniak, J.; Maxfield, S.J.; Mehta, A.; Meier, K.; Merkel, P.; Metlica, F.; Meyer, H.; Meyer, J.; Meyer, P.O.; Mikocki, S.; Milstead, D.; Mkrtchyan, T.; Mohr, R.; Mohrdieck, S.; Mondragon, M.N.; Moreau, F.; Morozov, A.; Morris, J.V.; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, Th.; Negri, I.; Nellen, G.; Newman, Paul R.; Nicholls, T.C.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Nunnemann, T.; Olsson, J.E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G.D.; Perez, E.; Phillips, J.P.; Pitzl, D.; Poschl, R.; Potachnikova, I.; Povh, B.; Rabbertz, K.; Radel, G.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Reyna, D.; Riess, S.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Royon, C.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Scheins, J.; Schilling, F.P.; Schleper, P.; Schmidt, D.; Schmitt, S.; Schoeffel, L.; Schoning, A.; Schorner, T.; Schroder, V.; Schultz-Coulon, H.C.; Sedlak, K.; Sefkow, F.; Chekelian, V.; Sheviakov, I.; Shtarkov, L.N.; Siegmon, G.; Sievers, P.; Sirois, Y.; Sloan, T.; Smirnov, P.; Solochenko, V.; Solovev, Y.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Steinhart, J.; Stella, B.; Stellberger, A.; Stiewe, J.; Straumann, U.; Struczinski, W.; Swart, M.; Tasevsky, M.; Tchernyshov, V.; Tchetchelnitski, S.; Thompson, Graham; Thompson, P.D.; Tobien, N.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Turnau, J.; Turney, J.E.; Tzamariudaki, E.; Udluft, S.; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vazdik, Y.; von Dombrowski, S.; Wacker, K.; Wallny, R.; Walter, T.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.G.; Wissing, C.; Wobisch, M.; Wollatz, H.; Wunsch, E.; Wyatt, A.C.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; Zsembery, J.; zur Nedden, M.
2000-01-01
A search for excited fermions f^* of the first generation in e^+p scattering at the collider HERA is presented using H1 data with an integrated luminosity of 37 pb^(-1). All electroweak decays of excited fermions, f^* -> f gamma, f W, f Z are considered and all possible final states resulting from the Z or W hadronic decays or decays into leptons of the first two generations are taken into account. No evidence for f^* production is found. Mass dependent exclusion limits on cross-sections and on the ratio of coupling constants to the compositeness scale are derived.
Minimally doubled fermions at one loop
Capitani, Stefano; Weber, Johannes; Wittig, Hartmut
2009-10-01
Minimally doubled fermions have been proposed as a cost-effective realization of chiral symmetry at non-zero lattice spacing. Using lattice perturbation theory at one loop, we study their renormalization properties. Specifically, we investigate the consequences of the breaking of hyper-cubic symmetry, which is a typical feature of this class of fermionic discretizations. Our results for the quark self-energy indicate that the four-momentum undergoes a renormalization which is linearly divergent. We also compute renormalization factors for quark bilinears, construct the conserved vector and axial-vector currents and verify that at one loop the renormalization factors of the latter are equal to one.
Testing UV-filtered ("fat-link") clover fermions
Capitani, Stefano; Durr, Stephan; Hoelbling, Christian
2006-01-01
We investigate filtered clover fermions, built from fat gauge links, both in one-loop perturbation theory and in numerical simulations. We use a variety of filtering recipes (APE, HYP, EXP, HEX), some of which are suitable for a HMC with dynamical fermions. A generic filtering together with a (fat-link) clover term yields fermions with much reduced chiral symmetry breaking.
Testing UV-filtered ("fat link") clover fermions
Durr, Stephan
2006-12-01
We investigate filtered clover fermions, built from fat gauge links, both in one-loop perturbation theory and in numerical simulations. We use a variety of filtering recipes (APE, HYP, EXP, HEX), some of which are suitable for a HMC with dynamical fermions. A generic filtering together with a (fat-link) clover term yields fermions with much reduced chiral symmetry breaking.
Remote telerobotic replacement for master-slave manipulator
Energy Technology Data Exchange (ETDEWEB)
Heckendorn, F.M.; Iverson, D.C. [Westinghouse Savannah River Company, Aiken, SC (United States); LaValle, D.R. [PaR Systems Inc., Shorview, MN (United States)
1997-05-01
A remotely replaceable telerobotic manipulator (TRM) has been developed and deployed at the Defense Waste Processing Facility (DWPF) in support of its radioactive operation. The TRM replaces a Master-Slave Manipulator (MSM). The TRM is in use for both routine and recovery operations for the radioactive waste vitrification melter, the primary production device within the DWPF. The arm was designed for deployment and operation using an existing MSM penetration. This replacement of an existing MSM with a high power robotic device demonstrates the capability to perform similar replacement in other operating facilities. The MSM`s were originally deployed in the DWPF to perform routine light capacity tasks. During the testing phase of the DWPF, prior to its radioactive startup in 5/96, the need to remove glass deposits that can form at the melter discharge during filling of glass containment canisters was identified. The combination of high radiation and contamination in the DWPF melter cell during radioactive operation eliminated personnel entry as a recovery option. Therefore remote cleaning methods had to be devised. The MSM`s had neither the reach nor the strength required for this task. It became apparent that a robust manipulator arm would be required for recovery from these potential melter discharge pluggage events. The existing wall penetrations, used for the MSM`s, could not be altered for seismic and radiological reasons. The new manipulator was required to be of considerable reach, due to existing physical layout, and strength, due to the glass removal requirement. Additionally, the device would have to compatible with high radiation and remote crane installation. The physical size of the manipulator and the weight of components must be consistent with the existing facilities. It was recognized early-on that a manipulator of sufficient strength to recover from a pluggage event would require robotic functions to constrain undesirable motions.
Energy Technology Data Exchange (ETDEWEB)
Enríquez, Marco; Rosas-Ortiz, Oscar, E-mail: orosas@fis.cinvestav.mx
2013-12-15
We review the properties of the Kronecker (direct, or tensor) product of square matrices A⊗B⊗C⋯ in terms of Hubbard operators. In its simplest form, a Hubbard operator X{sub n}{sup i,j} can be expressed as the n-square matrix which has entry 1 in position (i,j) and zero in all other entries. The algebra and group properties of the observables that define a multipartite quantum system are notably straightforward in such a framework. In particular, we use the Kronecker product in Hubbard notation to get the Clebsch–Gordan decomposition of the product group SU(2)×SU(2). Finally, the n-dimensional irreducible representations so obtained are used to derive closed forms of the Clebsch–Gordan coefficients that rule the addition of angular momenta. Our results can be further developed in many different directions. -- Highlights: •The Kronecker product is studied in terms of Hubbard operators. •Complicated calculations involving large matrices are reduced to simple relations of subscripts. •The algebraic properties of the quantum observables of multipartite systems are studied. •The Clebsch–Gordan coefficients are given in terms of hypergeometric {sub 3}F{sub 2} functions. •The results can be further developed in many different directions.
Zhong, Yin; Liu, Yu; Luo, Hong-Gang
2017-10-01
The periodic Anderson model (PAM), where local electron orbitals interplay with itinerant electronic carriers, plays an essential role in our understanding of heavy fermion materials. Motivated by recent proposals for simulating the Kondo lattice model (KLM) in terms of alkaline-earth metal atoms, we take another step toward the simulation of PAM, which includes the crucial charge/valence fluctuation of local f-electrons beyond purely low-energy spin fluctuation in the KLM. To realize PAM, a transition induced by a suitable laser between the electronic excited and ground state of alkaline-earth metal atoms (1 S 0⇌3 P 0) is introduced. This leads to effective hybridization between local electrons and conduction electrons in PAM. Generally, the SU( N) version of PAM can be realized by our proposal, which gives a unique opportunity to detect large- N physics without complexity in realistic materials. In the present work, high-temperature physical features of standard [ SU(2)] PAM with harmonic trapping potential are analyzed by quantum Monte Carlo and dynamic mean-field theory, where the Mott/orbital-selective Mott state was found to coexist with metallic states. Indications for near-future experiments are provided. We expect our theoretical proposal and (hopefully) forthcoming experiments will deepen our understanding of heavy fermion systems. At the same time, we hope these will trigger further studies on related Mott physics, quantum criticality, and non-trivial topology in both the inhomogeneous and nonequilibrium realms.
Fermion Masses and Mixing in SUSY Grand Unified Gauge Models with Extended Gut Gauge Groups
Energy Technology Data Exchange (ETDEWEB)
Chou, Chih-Lung
2005-04-05
The authors discuss a class of supersymmetric (SUSY) grand unified gauge (GUT) models based on the GUT symmetry G x G or G x G x G, where G denotes the GUT group that has the Standard Model symmetry (SU(3){sub c} x SU(2){sub L} x U(1){sub Y}) embedded as a subgroup. As motivated from string theory, these models are constructed without introducing any Higgs field of rani two or higher. Thus all the Higgs fields are in the fundamental representations of the extended GUT symmetry or, when G = SO(10), in the spinorial representation. These Higgs fields, when acquiring their vacuum expectation values, would break the extended GUT symmetry down to the Standard Model symmetry. In this dissertation, they argue that the features required of unified models, such as the Higgs doublet-triplet splitting, proton stability, and the hierarchy of fermion masses and mixing angles, could have natural explanations in the framework of the extended SUSY GUTs. Furthermore, they argue that the frameworks used previously to construct SO(10) GUT models using adjoint Higgs fields can naturally arise from the SO(10) x SO(10) and SO(10) x SO(10) x SO(10) models by integrating out heavy fermions. This observation thus suggests that the traditional SUSY GUT SO(10) theories can be viewed as the low energy effective theories generated by breaking the extended GUT symmetry down to the SO(10) symmetry.
Dynamical magnetic susceptibility in the spin-fermion model for cuprate superconductors
Val'kov, V. V.; Dzebisashvili, D. M.
2017-12-01
Using the method of diagram techniques for the spin and Fermi operators in the framework of the SU(2)- invariant spin-fermion model of the electron structure of the CuO 2 plane of copper oxides, we obtain an exact representation of the Matsubara Green's function D ⊥( k, iω m ) of the subsystem of localized spins. This representation includes the Larkin mass operator ΣL( k, iω m ) and the strength and polarization operators P( k, iω m ) and Π( k, iω m ). The calculation in the one-loop approximation of the mass and strength operators for the Heisenberg spin system in the quantum spin-liquid state allows writing the Green's function D ⊥( k, iω m ) explicitly and establishing a relation to the result of Shimahara and Takada. An essential point in the developed approach is taking the spin-polaron nature of the Fermi quasiparticles in the spin-fermion model into account in finding the contribution of oxygen holes to the spin response in terms of the polarization operator Π( k, iω m ).
Neutrino mixing and masses in a left-right model with mirror fermions
Energy Technology Data Exchange (ETDEWEB)
Gaitan, R. [UNAM, Centro de Investigaciones Teoricas, FES, Apartado Postal 142, Cuatitlan-Izcalli, Mexico (Mexico); Hernandez-Galeana, A.; Rivera-Rebolledo, J.M. [I.P.N., Departamento de Fisica, Escuela Superior de Fisica y Matematica, Mexico D.F. (Mexico); Fernandez de Cordoba, P. [Universidad Politecnica de Valencia, Instituto de Matematica Pura y Aplicada, Valencia (Spain)
2012-01-15
In the framework of a left-right model containing mirror fermions with gauge group SU(3){sub C} x SU(2){sub L} x SU(2){sub R} x U(1){sub Y}', we estimate the neutrino masses, which are found to be consistent with their experimental bounds and hierarchy. We evaluate the decay rates of the Lepton Flavor Violation (LFV) processes {mu}{yields}e{gamma}, {tau}{yields}{mu}{gamma} and {tau}{yields}e{gamma}. We obtain upper limits for the flavor-changing branching ratios in agreement with their present experimental bounds. We also estimate the decay rates of heavy Majorana neutrinos in the channels N{yields}W {sup {+-}}l{sup -+}, N{yields}Z{nu}{sub l} and N{yields}H{nu}{sub l}, which are roughly equal for large values of the heavy neutrino mass. Starting from the most general Majorana neutrino mass matrix, the smallness of active neutrino masses turns out from the interplay of the hierarchy of the involved scales and the double application of seesaw mechanism. An appropriate parameterization on the structure of the neutrino mass matrix imposing a symmetric mixing of electron neutrino with muon and tau neutrinos leads to tri-bimaximal mixing matrix for light neutrinos. (orig.)
Search for heavy fermions with the ATLAS experiment at the LHC collider
AUTHOR|(INSPIRE)INSPIRE-00359999; Santiago, José; Onofre, António
In the present thesis a search for new heavy fermions using LHC data collected in 2012 by the ATLAS experiment is presented. In particular, a search for pair and single production of vector-like quarks with electric charge 2/3 ($T$) and -1/3 ($B$) decaying to a $Z$ boson is discussed. For this search the analysis was divided in two channels, depending on the lepton multiplicity, and both channels were combined at the end for the final results. Since no evidence for signal was found, limits on the mass of the vector-like quarks were evaluated. The observed (expected) limit on the mass of an $SU(2)$ singlet $T$ quark is 655~GeV (625~GeV), while the observed (expected) limit on the mass of a $T$ quark in a $(T,B)$ doublet is 735~GeV (720~GeV). The observed (expected) limit on the mass of an $SU(2)$ singlet $B$ quark is 685~GeV (670~GeV), while the observed (expected) limit on the mass of a $B$ quark in a $(B,Y)$ doublet is 755~GeV (755~GeV). The impact of a heavy gluon in the searches for pair production of vect...
Stumpf, H.
2003-01-01
Generalized de Broglie-Bargmann-Wigner (BBW) equations are relativistically invariant quantum mechanical many body equations with nontrivial interaction, selfregularization and probability interpretation. Owing to these properties these equations are a suitable means for describing relativistic bound states of fermions. In accordance with de Broglie's fusion theory and modern assumptions about the partonic substructure of elementary fermions, i.e., leptons and quarks, the three-body generalized BBW-equations are investigated. The transformation properties and quantum numbers of the three-parton equations under the relevant group actions are elaborated in detail. Section 3 deals with the action of the isospin group SU(2), a U(1) global gauge group for the fermion number, the hypercharge and charge generators. The resulting quantum numbers of the composite partonic systems can be adapted to those of the phenomenological particles to be described. The space-time transformations and in particular rotations generated by angular momentum operators are considered in Section 4. Based on the compatibility of the BBW-equations and the group theoretical constraints, in Sect. 5 integral equations are formulated in a representation with diagonal energy and total angular momentum variables. The paper provides new insight into the solution space and quantum labels of resulting integral equations for three parton states and prepares the ground for representing leptons and quarks as composite systems.
Axial gravity, massless fermions and trace anomalies
Bonora, L.; Cvitan, M.; Prester, P. Dominis; Pereira, A. Duarte; Giaccari, S.; Štemberga, T.
2017-08-01
This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones.
Born-Kothari Condensation for Fermions
Directory of Open Access Journals (Sweden)
Arnab Ghosh
2017-09-01
Full Text Available In the spirit of Bose–Einstein condensation, we present a detailed account of the statistical description of the condensation phenomena for a Fermi–Dirac gas following the works of Born and Kothari. For bosons, while the condensed phase below a certain critical temperature, permits macroscopic occupation at the lowest energy single particle state, for fermions, due to Pauli exclusion principle, the condensed phase occurs only in the form of a single occupancy dense modes at the highest energy state. In spite of these rudimentary differences, our recent findings [Ghosh and Ray, 2017] identify the foregoing phenomenon as condensation-like coherence among fermions in an analogous way to Bose–Einstein condensate which is collectively described by a coherent matter wave. To reach the above conclusion, we employ the close relationship between the statistical methods of bosonic and fermionic fields pioneered by Cahill and Glauber. In addition to our previous results, we described in this mini-review that the highest momentum (energy for individual fermions, prerequisite for the condensation process, can be specified in terms of the natural length and energy scales of the problem. The existence of such condensed phases, which are of obvious significance in the context of elementary particles, have also been scrutinized.
SU(3) sextet model with Wilson fermions
DEFF Research Database (Denmark)
Hansen, Martin; Drach, Vincent; Pica, Claudio
2017-01-01
We investigate the spectrum and IR properties of the SU(3) "sextet" model with two Dirac fermions in the two-index symmetric representation via lattice simulations. This model is a prime candidate for a realization of walking technicolor, which features a minimal matter content and it is expected...
Dual of QCD with One Adjoint Fermion
DEFF Research Database (Denmark)
Mojaza, Matin; Nardecchia, Marco; Pica, Claudio
2011-01-01
We construct the magnetic dual of QCD with one adjoint Weyl fermion. The dual is a consistent solution of the 't Hooft anomaly matching conditions, allows for flavor decoupling and remarkably constitutes the first nonsupersymmetric dual valid for any number of colors. The dual allows to bound the...
Fermion Helicity Flip Induced by Torsion Field
Capozziello, S.; Iovane, G.; Lambiase, G.; Stornaiolo, C.
1999-01-01
We show that in theories of gravitation with torsion the helicity of fermion particles is not conserved and we calculate the probability of spin flip, which is related to the anti-symmetric part of affine connection. Some cosmological consequences are discussed.
Exploring a hidden fermionic dark sector
Indian Academy of Sciences (India)
2017-10-09
Oct 9, 2017 ... ... global U ( 1 ) H charge while the gauge bosons and dark scalar do not have any global U ( 1 ) H charge. The lightest fermion in dark sector can serve as a potential dark matter candidate. We investigate whether the proposed dark matter candidate can explain indirect detection results from galactic centre.
A Study of Dirac Fermionic Dark Matters
Chua, Chun-Khiang; Hsieh, Ron-Chou
2013-01-01
We study pure weak eigenstate Dirac fermionic dark matters (DM). We consider WIMP with renormalizable interaction. According to results of direct searches and the nature of DM (electrical neutral and being a pure weak eigenstate), the quantum number of DM is determined to be $I_3=Y=0$. There are only two possible cases: either DM has non-vanishing weak isospin ($I\
Multiple superconducting phases in heavy fermion compounds ...
Indian Academy of Sciences (India)
Here we show that multiple superconducting phases are present in heavy fermion superconductors, CeCoIn5 [2] and PrOs4Sb12 [3] , both of which were discovered very recently. The superconducting gap function of PrOs4Sb12 was investigated using thermal transport measurements in magnetic field rotated relative to the.
Axial gravity, massless fermions and trace anomalies
Energy Technology Data Exchange (ETDEWEB)
Bonora, L. [International School for Advanced Studies (SISSA), Trieste (Italy); KEK, Tsukuba (Japan). KEK Theory Center; INFN, Sezione di Trieste (Italy); Cvitan, M.; Giaccari, S.; Stemberga, T. [Zagreb Univ. (Croatia). Dept. of Physics; Prester, P.D. [Rijeka Univ. (Croatia). Dept. of Physics; Pereira, A.D. [UERJ-Univ. Estadual do Rio de Janeiro (Brazil). Dept. de Fisica Teorica; UFF-Univ. Federal Fluminense, Niteroi (Brazil). Inst. de Fisica
2017-08-15
This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones. (orig.)
Trapping fermionic and bosonic helium atoms
Stas, R.J.W.
2005-01-01
This thesis presents experimental and theoretical work performed at the Laser Centre of the Vrije Universiteit in Amsterdam to study laser-cooled metastable triplet helium atoms. Samples containing about 3x10^8 helium atoms-either fermionic helium-3 atoms, bosonic helium-4 atoms or mixtures
Magnetic fluctuations in heavy-fermion metals
DEFF Research Database (Denmark)
Mason, T.E.; Petersen, T.; Aeppli, G.
1995-01-01
Elastic and inelastic neutron scattering have been used to study the antiferromagnetic ordering and magnetic excitations of the U heavy-fermion superconductors UPd2Al3 and URu2Si2 above and below T-N. While both materials exhibit the coexistence of superconductivity and antiferromagnetic order, t...
Bosonic and Fermionic Dipoles on a Ring
DEFF Research Database (Denmark)
Zöllner, Sascha; Bruun, Georg; Pethick, Christopher
2011-01-01
We show that dipolar bosons and fermions confined in a quasi-one-dimensional ring trap exhibit a rich variety of states because their interaction is inhomogeneous. For purely repulsive interactions, with increasing strength of the dipolar coupling there is a crossover from a gaslike state to an i...
Fermionic continuous spin gauge field in (AdS space
Directory of Open Access Journals (Sweden)
R.R. Metsaev
2017-10-01
Full Text Available Fermionic continuous spin field propagating in (AdS space–time is studied. Gauge invariant Lagrangian formulation for such fermionic field is developed. Lagrangian of the fermionic continuous spin field is constructed in terms of triple gamma-traceless tensor–spinor Dirac fields, while gauge symmetries are realized by using gamma-traceless gauge transformation parameters. It is demonstrated that partition function of fermionic continuous spin field is equal to one. Modified de Donder gauge condition that considerably simplifies analysis of equations of motion is found. Decoupling limits leading to arbitrary spin massless, partial-massless, and massive fermionic fields are studied.
Thermodynamics of SU(2 quantum Yang-Mills theory and CMB anomalies
Directory of Open Access Journals (Sweden)
Hofmann Ralf
2014-04-01
Full Text Available A brief review of effective SU(2 Yang-Mills thermodynamics in the deconfining phase is given, including the construction of the thermal ground-state estimate in terms of an inert, adjoint scalar field φ, based on non-propagating (antiselfdual field configurations of topological charge unity. We also discuss kinematic constraints on interacting propagating gauge fields implied by the according spatial coarse-graining, and we explain why the screening physics of an SU(2 photon is subject to an electric-magnetically dual interpretation. This argument relies on the fact that only (anticalorons of scale parameter ρ ∼ |φ|−1 contribute to the coarse-graining required for thermal-ground-state emergence at temperature T. Thus, use of the effective gauge coupling e in the (anticaloron action is justified, yielding the value ħ for the latter at almost all temperatures. As a consequence, the indeterministic transition of initial to final plane waves caused by an effective, pointlike vertex is fundamentally mediated in Euclidean time by a single (anticaloron being part of the thermal ground state. Next, we elucidate how a low-frequency excess of line temperature in the Cosmic Microwave Background (CMB determines the value of the critical temperature of the deconfining-preconfining phase transition of an SU(2 Yang-Mills theory postulated to describe photon propagation, and we describe how, starting at a redshift of about unity, SU(2 photons collectively work 3D temperature depressions into the CMB. Upon projection along a line of sight, a given depression influences the present CMB sky in a cosmologically local way, possibly explaining the large-angle anomalies confirmed recently by the Planck collaboration. Finally, six relativistic polarisations residing in the SU(2 vector modes roughly match the number of degrees of freedom in cosmic neutrinos (Planck which would disqualify the latter as radiation. Indeed, if interpreted as single center
Ending the history of silence: reconstructing European Slave trading in the Indian Ocean
Directory of Open Access Journals (Sweden)
Richard B. Allen
Full Text Available Abstract: Thirty-eight years ago, Hubert Gerbeau discussed the problems that contributed to the “history of silence” surrounding slave trading in the Indian Ocean. While the publication of an expanding body of scholarship since the late 1980s demonstrates that this silence is not as deafening as it once was, our knowledge and understanding of this traffic in chattel labor remains far from complete. This article discusses the problems surrounding attempts to reconstruct European slave trading in the Indian Ocean between 1500 and 1850. Recently created inventories of British East India Company slaving voyages during the seventeenth and eighteenth centuries and of French, Portuguese, and other voyages involving the Mascarene Islands of Mauritius and Réunion between 1670 and the 1830s not only shed light on the nature and dynamics of British and French slave trading in the Indian Ocean, but also highlight topics and issues that future research on European slave trading within and beyond this oceanic world will need to address.
Universal relations with fermionic dark matter
Krut, A.; Argüelles, C. R.; Rueda, J. A.; Ruffini, R.
2018-01-01
We have recently introduced a new model for the distribution of dark matter (DM) in galaxies, the Ruffini-Argüelles-Rueda (RAR) model, based on a self-gravitating system of massive fermions at finite temperatures. The RAR model, for fermion masses above keV, successfully describes the DM halos in galaxies, and predicts the existence of a denser quantum core towards the center of each configuration. We demonstrate here, for the first time, that the introduction of a cutoff in the fermion phase-space distribution, necessary to account for galaxies finite size and mass, defines a new solution with a compact quantum core which represents an alternative to the central black hole (BH) scenario for SgrA*. For a fermion mass in the range 48keV ≤ mc2 ≤ 345keV, the DM halo distribution fulfills the most recent data of the Milky Way rotation curves while harbors a dense quantum core of 4×106M⊙ within the S2 star pericenter. In particular, for a fermion mass of mc2 ˜ 50keV the model is able to explain the DM halos from typical dwarf spheroidal to normal elliptical galaxies, while harboring dark and massive compact objects from ˜ 103M⊙ tp to 108M⊙ at their respective centers. The model is shown to be in good agreement with different observationally inferred universal relations, such as the ones connecting DM halos with supermassive dark central objects. Finally, the model provides a natural mechanism for the formation of supermassive BHs as heavy as few ˜ 108M⊙. We argue that larger BH masses (few ˜ 109-10M⊙) may be achieved by assuming subsequent accretion processes onto the above heavy seeds, depending on accretion efficiency and environment.
Universal relations with fermionic dark matter
Directory of Open Access Journals (Sweden)
Krut A.
2018-01-01
Full Text Available We have recently introduced a new model for the distribution of dark matter (DM in galaxies, the Ruffini-Argüelles-Rueda (RAR model, based on a self-gravitating system of massive fermions at finite temperatures. The RAR model, for fermion masses above keV, successfully describes the DM halos in galaxies, and predicts the existence of a denser quantum core towards the center of each configuration. We demonstrate here, for the first time, that the introduction of a cutoff in the fermion phase-space distribution, necessary to account for galaxies finite size and mass, defines a new solution with a compact quantum core which represents an alternative to the central black hole (BH scenario for SgrA*. For a fermion mass in the range 48keV ≤ mc2 ≤ 345keV, the DM halo distribution fulfills the most recent data of the Milky Way rotation curves while harbors a dense quantum core of 4×106M⊙ within the S2 star pericenter. In particular, for a fermion mass of mc2 ∼ 50keV the model is able to explain the DM halos from typical dwarf spheroidal to normal elliptical galaxies, while harboring dark and massive compact objects from ∼ 103M⊙ tp to 108M⊙ at their respective centers. The model is shown to be in good agreement with different observationally inferred universal relations, such as the ones connecting DM halos with supermassive dark central objects. Finally, the model provides a natural mechanism for the formation of supermassive BHs as heavy as few ∼ 108M⊙. We argue that larger BH masses (few ∼ 109−10M⊙ may be achieved by assuming subsequent accretion processes onto the above heavy seeds, depending on accretion efficiency and environment.
Fermions in hybrid loop quantum cosmology
Elizaga Navascués, Beatriz; Mena Marugán, Guillermo A.; Martín-Benito, Mercedes
2017-08-01
This work pioneers the quantization of primordial fermion perturbations in hybrid loop quantum cosmology (LQC). We consider a Dirac field coupled to a spatially flat, homogeneous, and isotropic cosmology, sourced by a scalar inflaton, and treat the Dirac field as a perturbation. We describe the inhomogeneities of this field in terms of creation and annihilation variables, chosen to admit a unitary evolution if the Dirac fermion were treated as a test field. Considering instead the full system, we truncate its action at quadratic perturbative order and construct a canonical formulation. In particular this implies that, in the global Hamiltonian constraint of the model, the contribution of the homogeneous sector is corrected with a quadratic perturbative term. We then adopt the hybrid LQC approach to quantize the full model, combining the loop representation of the homogeneous geometry with the Fock quantization of the inhomogeneities. We assume a Born-Oppenheimer ansatz for physical states and show how to obtain a Schrödinger equation for the quantum evolution of the perturbations, where the role of time is played by the homogeneous inflaton. We prove that the resulting quantum evolution of the Dirac field is indeed unitary, despite the fact that the underlying homogeneous geometry has been quantized as well. Remarkably, in such evolution, the fermion field couples to an infinite sequence of quantum moments of the homogeneous geometry. Moreover, the evolved Fock vacuum of our fermion perturbations is shown to be an exact solution of the Schrödinger equation. Finally, we discuss in detail the quantum backreaction that the fermion field introduces in the global Hamiltonian constraint. For completeness, our quantum study includes since the beginning (gauge-invariant) scalar and tensor perturbations, that were studied in previous works.
From instantons to sphalerons: Time-dependent periodic solutions of SU(2)-Higgs theory
Energy Technology Data Exchange (ETDEWEB)
Frost, K.L.; Yaffe, L.G. [Department of Physics, University of Washington, Seattle, Washington 98105-1560 (United States)
1999-11-01
We solve numerically for periodic, spherically symmetric, classical solutions of SU(2)-Higgs theory in four-dimensional Euclidean space. In the limit of short periods the solutions approach tiny instanton{endash}anti-instanton superpositions while, for longer periods, the solutions merge with the static sphaleron. A previously predicted bifurcation point, where two branches of periodic solutions meet, appears for Higgs boson masses larger than 3.091M{sub W}. {copyright} {ital 1999} {ital The American Physical Society}
Template Composite Dark Matter : SU(2) gauge theory with 2 fundamental flavours
Drach, Vincent; Pica, Claudio; Rantaharju, Jarno; Sannino, Francesco
2015-11-13
We present a non perturbative study of SU(2) gauge theory with two fundamental Dirac flavours. We discuss how the model can be used as a template for composite Dark Matter (DM). We estimate one particular interaction of the DM candidate with the Standard Model : the interaction through photon exchange computing the electric polarizability of the DM candidate. Finally, we briefly discuss the viability of the model given the present experimental constraints.
Quantum entanglement in the one-dimensional spin-orbital SU (2 )⊗XXZ model
You, Wen-Long; Horsch, Peter; Oleś, Andrzej M.
2015-08-01
We investigate the phase diagram and the spin-orbital entanglement of a one-dimensional SU (2 )⊗XXZ model with SU(2) spin exchange and anisotropic XXZ orbital exchange interactions and negative exchange coupling constant. As a unique feature, the spin-orbital entanglement entropy in the entangled ground states increases here linearly with system size. In the case of Ising orbital interactions, we identify an emergent phase with long-range spin-singlet dimer correlations triggered by a quadrupling of correlations in the orbital sector. The peculiar translational-invariant spin-singlet dimer phase has finite von Neumann entanglement entropy and survives when orbital quantum fluctuations are included. It even persists in the isotropic SU (2 )⊗SU (2) limit. Surprisingly, for finite transverse orbital coupling, the long-range spin-singlet correlations also coexist in the antiferromagnetic spin and alternating orbital phase making this phase also unconventional. Moreover, we also find a complementary orbital singlet phase that exists in the isotropic case but does not extend to the Ising limit. The nature of entanglement appears essentially different from that found in the frequently discussed model with positive coupling. Furthermore, we investigate the collective spin and orbital wave excitations of the disentangled ferromagnetic-spin/ferro-orbital ground state and explore the continuum of spin-orbital excitations. Interestingly, one finds among the latter excitations two modes of exciton bound states. Their spin-orbital correlations differ from the remaining continuum states and exhibit logarithmic scaling of the von Neumann entropy with increasing system size. We demonstrate that spin-orbital excitons can be experimentally explored using resonant inelastic x-ray scattering, where the strongly entangled exciton states can be easily distinguished from the spin-orbital continuum.
The Slave Population in Pernambuco, Brazil, 1560-1872: A macrodemographic reconstruction
Directory of Open Access Journals (Sweden)
Heitor P. de Moura Filho
2015-08-01
Full Text Available This paper exposes a demographic model to represent the evolution of the population of African slaves brought to the province of Pernambuco, Brazil, from 1560 to 1872, including their descendants. The main conclusion at this stage of the research is the confirmation that realistic combinations of mortality and fertility parameters, within the wide intervals acknowledged by the literature, do, in fact, generate populations in size and – more importantly – with the sex and age distributions uncovered in the first nation-wide census for Brazil, in 1872. Such combinations of parameters also reinforce the thesis that the slave trade was the main motor for the growth of the slave population and its descendants.
Reproductive conflict in social insects: male production by workers in a slave-making ant.
Brunner, Elisabeth; Trindl, Andreas; Falk, Karl H; Heinze, Juergen; D'Ettorre, Patrizia
2005-11-01
In insect societies, workers cooperate but may also pursue their individual interests, such as laying viable male eggs. The case of obligatory slave-making ants is of particular interest because workers do not engage in maintenance activities and foraging. Therefore, worker egg laying is expected to be less detrimental for colony efficiency than in related, nonparasitic species. Furthermore, as slave-making workers usually do not perform brood care and thus might have little power in manipulating sex allocation, they might be more strongly selected to increase their direct fitness by producing their own sons than workers in nonparasitic species. In this study we investigated worker reproduction in four natural colonies of the slave-making ant Polyergus rufescens, using highly variable microsatellite markers. Our results show that workers produce up to 100% of the males. This study thus presents the first direct evidence of an almost complete takeover of male reproduction by workers in ants.
Mambrini, Matthieu; Poilblanc, Didier
2016-01-01
We elaborate a simple classification scheme of all rank-5 SU(2)-spin rotational symmetric tensors according to i) the on-site physical spin-$S$, (ii) the local Hilbert space $V^{\\otimes 4}$ of the four virtual (composite) spins attached to each site and (iii) the irreducible representations of the $C_{4v}$ point group of the square lattice. We apply our scheme to draw a complete list of all SU(2)-symmetric translationally and rotationally-invariant Projected Entangled Pair States (PEPS) with bond dimension $D\\leqslant 6$. All known SU(2)-symmetric PEPS on the square lattice are recovered and simple generalizations are provided in some cases. More generally, to each of our symmetry class can be associated a $({\\cal D}-1)$-dimensional manifold of spin liquids (potentially) preserving lattice symmetries and defined in terms of ${\\cal D}$ independent tensors of a given bond dimension $D$. In addition, generic (low-dimensional) families of PEPS explicitly breaking either (i) particular point-group lattice symmetri...
Effect of SU(2) symmetry on many-body localization and thermalization
Protopopov, Ivan V.; Ho, Wen Wei; Abanin, Dmitry A.
2017-07-01
The many-body localized (MBL) phase is characterized by a complete set of quasilocal integrals of motion and area-law entanglement of excited eigenstates. We study the effect of non-Abelian continuous symmetries on MBL, considering the case of SU(2 ) symmetric disordered spin chains. The SU(2 ) symmetry imposes strong constraints on the entanglement structure of the eigenstates, precluding conventional MBL. We construct a fixed-point Hamiltonian, which realizes a nonergodic (but non-MBL) phase characterized by eigenstates having logarithmic scaling of entanglement with the system size, as well as an incomplete set of quasilocal integrals of motion. We study the response of such a phase to local symmetric perturbations, finding that even weak perturbations induce multispin resonances. We conclude that the nonergodic phase is generally unstable and that SU(2 ) symmetry implies thermalization. The approach introduced in this Rapid Communication can be used to study dynamics in disordered systems with non-Abelian symmetries, and provides a starting point for searching nonergodic phases beyond conventional MBL.
[Physicians and pharmacists in the Puerto Rican slave trade: Ponce, 1815-1830].
PérezVega, Ivette
2010-01-01
Slavery was a commerce controlled by foreigners, like physician Robert Proust, pharmacist Gaspar Duprel, and Slave trader Juan. B. Saubot in Ponce. The trading of negroes is evidence since 1816 but intensified in 1824. By 1825, Ponce was full of slaves. It continued fiercely until 1830 supported by local revenue and investments, however, never developed its own. Slavery grew parallel to the development of the "hacienda", and as such, to the wealth of the foreign businessman. These are considered the first golden years of Ponce's and Puerto Rico's economic development, which stimulated overall progress, and social well-being.
Reproductive conflict in social insects: Male production by workers in a slave-making ant
DEFF Research Database (Denmark)
Brunner, Elizabeth; Trindl, Andreas; Falk, Karl H.
2005-01-01
AbstractIn insect societies, workers cooperate but may also pursue their individual interests, such as laying viable male eggs. The case of obligatory slave-making ants is of particular interest because workers do not engage in maintenance activities and foraging. Therefore, worker egg laying...... by producing their own sons than workers in nonparasitic species. In this study we investigated worker reproduction in four natural colonies of the slave-making ant Polyergus rufescens, using highly variable microsatellite markers. Our results show that workers produce up to 100% of the males. This study thus...... presents the first direct evidence of an almost complete takeover of male reproduction by workers in ants....
Directory of Open Access Journals (Sweden)
Fábio Pereira de Carvalho
2013-06-01
Full Text Available This article seeks argue that the search for autonomy among slaves necessarily created hierarchies within the community where they were inserted. Through two cases compared, George in U.S. and Lino in Brazil, seeks to show that a notion of slave community was built by the social actors who were part of it
Dalrymple-Smith, A.E.; Woltjer, P.J.
2016-01-01
Using a newly constructed dataset on the quantities and prices of African commodities over the long 18th century this paper provides new insights into the changing nature of the non-slave trade with West Africa in the era before the abolition of the British transatlantic slave trade. We find that
Pelckmans, L.
2012-01-01
This article examines the migration trajectories of individuals of slave descent and ‘mixed descent’ (children of slave concubines) in a royal family network from the Haayre region of central Mali. Focusing on the twentieth century, it considers the extent to which social status has defined options
Jasinski, James
2007-01-01
In August 1843 Presbyterian minister Henry Highland Garnet delivered his "Address to the Slaves of the United States of America" to the National Convention of Colored Citizens in Buffalo, NY. While often read (and almost as often dismissed) as either an unqualified call for a violent slave rebellion or, at the least, a celebration of…
Exact renormalization group study of fermionic theories
Comellas, Jordi; Kubyshin, Yuri; Moreno, Enrique
1997-02-01
The exact renormalization group approach (ERG) is developed for the case of pure fermionic theories by deriving a Grassmann version of the ERG equation and applying it to the study of fixed point solutions and critical exponents of the two-dimensional chiral Gross-Neveu model. An approximation based on the derivative expansion and a further truncation in the number of fields is used. Two solutions are obtained analytically in the limit N → ∞, with N being the number of fermionic species. For finite N some fixed point solutions, with their anomalous dimensions and critical exponents, are computed numerically. The issue of separation of physical results from the numerous spurious ones is discussed. We argue that one of the solutions we find can be identified with that of Dashen and Frishman, whereas the others seem to be new ones.
Supersymmetric Extension of Technicolor & Fermion Mass Generation
DEFF Research Database (Denmark)
Antola, Matti; Di Chiara, Stefano; Sannino, Francesco
2012-01-01
We provide a complete extension of Minimal Walking Technicolor able to account for the standard model fermion masses. The model is supersymmetric at energies greater or equal to the technicolor compositeness scale. We integrate out, at the supersymmetry breaking scale, the elementary Higgses. We...... use the resulting four-fermion operators to derive the low energy effective theory. We then determine the associated tree-level vacuum and low energy spectrum properties. Furthermore we investigate the phenomenological viability of the model by comparing its predictions with electroweak precision...... tests and experimental bounds on the mass spectrum. We then turn to the composite Higgs phenomenology at the LHC and show that current data are already constraining the parameter space of the model....
Higgs Portal Inflation with Fermionic Dark Matter
Directory of Open Access Journals (Sweden)
Aravind Aditya
2018-01-01
Full Text Available We discuss the inflationary model presented in [1], involving a gauge singlet scalar field and fermionic dark matter added to the standard model. Either the Higgs or the singlet scalar could play the role of the inflaton, and slow roll is realized through its non-minimal coupling to gravity. The effective scalar potential is stabilized by the mixing between the scalars as well as the coupling with the fermionic field. Mixing of the two scalars also provides a portal to dark matter. Constraints on the model come from perturbativity and stability, collider searches and dark matter constraints and impose a constraining relationship on the masses of dark matter and scalar fields. Inflationary predictions are generically consistent with current Planck data.
Higgs Portal Inflation with Fermionic Dark Matter
Aravind, Aditya; Xiao, Minglei; Yu, Jiang-Hao
2018-01-01
We discuss the inflationary model presented in [1], involving a gauge singlet scalar field and fermionic dark matter added to the standard model. Either the Higgs or the singlet scalar could play the role of the inflaton, and slow roll is realized through its non-minimal coupling to gravity. The effective scalar potential is stabilized by the mixing between the scalars as well as the coupling with the fermionic field. Mixing of the two scalars also provides a portal to dark matter. Constraints on the model come from perturbativity and stability, collider searches and dark matter constraints and impose a constraining relationship on the masses of dark matter and scalar fields. Inflationary predictions are generically consistent with current Planck data.
On the integrable gravity coupled to fermions
Belinski, Vladimir A.
2017-06-01
In the present letter we indicate an extension of the pure gravity inverse scattering integration technique to the case when fermions (introduced on the base of supersymmetry) are present. In this way the integrability technique for simple (N = 1) supergravity in two space-time dimensions coupled to the matter fields taking values in the Lie algebra of E 8 (+ 8) group is developed. This theory contains matter living only in one Weyl representation of SO (16) and represents the reduction to two dimensions of the three-dimensional simple supergravity constructed in [1]. Our spectral linear problem use superspace and covers the complete set of principal bosonic and fermionic equations of motion. This linear system, as in pure gravity, contains only the first order poles with respect to the spectral parameter. The procedure of constructing the exact super-solitonic solutions is outlined.
Extending exchange symmetry beyond bosons and fermions
Tichy, Malte C.; Mølmer, Klaus
2017-08-01
We study quantum many-body states of particles subject to a more general exchange symmetry than the behavior under pairwise exchange obeyed by bosons and fermions. We refer to these hypothetical particles as immanons because the scalar product of states with the generalized exchange symmetry is the immanant of the matrix containing all mutual scalar products of the occupied single-particle states, a generalization of the determinant and permanent applied for fermions and bosons. Immanons are shown to obey a partial Pauli principle that forbids the occupation of single-particle states above certain threshold numbers. This has measurable consequences for their tendency to favor or oppose multiple occupation of single-particle modes, and it links conjectured mathematical properties of immanants to the expected outcome of a physical Gedanken experiment.
Li, Xiaofan; Fang, Jian-An; Li, Huiyuan
2017-09-01
This paper investigates master-slave exponential synchronization for a class of complex-valued memristor-based neural networks with time-varying delays via discontinuous impulsive control. Firstly, the master and slave complex-valued memristor-based neural networks with time-varying delays are translated to two real-valued memristor-based neural networks. Secondly, an impulsive control law is constructed and utilized to guarantee master-slave exponential synchronization of the neural networks. Thirdly, the master-slave synchronization problems are transformed into the stability problems of the master-slave error system. By employing linear matrix inequality (LMI) technique and constructing an appropriate Lyapunov-Krasovskii functional, some sufficient synchronization criteria are derived. Finally, a numerical simulation is provided to illustrate the effectiveness of the obtained theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.
Symmetries of Ginsparg-Wilson Chiral Fermions
Mandula, Jeffrey E.
2009-01-01
The group structure of the variant chiral symmetry discovered by Luscher in the Ginsparg-Wilson description of lattice chiral fermions is analyzed. It is shown that the group contains an infinite number of linearly independent symmetry generators, and the Lie algebra is given explicitly. CP is an automorphism of this extended chiral group, and the CP transformation properties of the symmetry generators are found. The group has an infinite-parameter invariant subgroup, and the factor group, wh...
Exploring a hidden fermionic dark sector
Indian Academy of Sciences (India)
Debasish Majumdar
2017-10-09
Oct 9, 2017 ... galaxy, can annihilate into a pair of fermions which can produce excess of γ-ray flux, neutrino flux etc. Obser- vation of any such excess from these astrophysical sites can then be assumed to be due to annihilation of dark matter at these sites. Recent study of Fermi-LAT data. [36] for GC γ-ray flux from GC by ...
Hypercubic smeared links for dynamical fermions
Energy Technology Data Exchange (ETDEWEB)
Hasenfratz, A.; Hoffmann, R. [Colorado Univ., Boulder, CO (United States). Dept. of Physics; Schaefer, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2007-02-15
We investigate a variant of hypercubic gauge link smearing where the SU(3) projection is replaced with a normalization to the corresponding unitary group. This smearing is differentiable and thus suitable for use in dynamical fermion simulations using molecular dynamics type algorithms. We show that this smearing is as efficient as projected hypercubic smearing in removing ultraviolet noise from the gauge fields. We test the normalized hypercubic smearing in dynamical improved (clover) Wilson and valence overlap simulations. (orig.)
Optical Lattice Simulations of Correlated Fermions
2013-10-04
Baksmaty, Hong Lu, C J Bolech, Han Pu. A Bogoliubov–de Gennes study of trapped spin-imbalanced unitary Fermi gases, New Journal of Physics, (05 2011): 0...October 2009). 9. Leslie O. Baksmaty, " Unitary Superfluidity of Polarized Fermionic Gases in Highly Elongated Traps", DAMOP, May 2010. 10. Satyan...other than abstracts): Received Paper TOTAL: Books Number of Manuscripts: Received Paper TOTAL: Patents Submitted Patents Awarded Awards 2009 - David
Symmetries of Ginsparg-Wilson chiral fermions
Mandula, Jeffrey E.
2009-10-01
The group structure of the variant chiral symmetry discovered by Lüscher in the Ginsparg-Wilson description of lattice chiral fermions is analyzed. It is shown that the group contains an infinite number of linearly independent symmetry generators, and the Lie algebra is given explicitly. CP is an automorphism of this extended chiral group, and the CP transformation properties of the symmetry generators are found. The group has an infinite-parameter invariant subgroup, and the factor group, whose elements are its cosets, is isomorphic to the continuum chiral symmetry group. Features of the currents associated with these symmetries are discussed, including the fact that some different, noncommuting symmetry generators lead to the same Noether current. These are universal features of lattice chiral fermions based on the Ginsparg-Wilson relation; they occur in the overlap, domain-wall, and perfect-action formulations. In a solvable example, free overlap fermions, these noncanonical elements of lattice chiral symmetry are related to complex energy singularities that violate reflection positivity and impede continuation to Minkowski space.
Fermion pairing in Bose-Fermi mixtures
Matera, F.
2003-10-01
An effective interaction between fermions in a Bose-Fermi mixture is derived. It is induced by density fluctuations of the bosonic background. The contributions from states containing both one and two virtual phonons are taken into account self-consistently. The time dependence of the effective interaction has been removed by assuming that the velocity of the fermions at the Fermi surface is much larger than the sound velocity in the Bose gas. This assumption is more appropriate for the actual experimental situations than the usual approximation of neglecting retardation effects. The effective interaction turns out to be attractive and, as a consequence, can give rise to a superconducting phase in the Fermi component of the mixture. The fermions are considered in only one magnetic state, so that pairing can be effective only in odd-l channels. It has been found that the onset of the superconducting phase can occur at temperatures (>100 nK) of the same order of magnitude as the Fermi temperature (˜300 nK), and the energy gap in the excitation spectrum is a small fraction (˜1%) of the Fermi energy.
Wu, Yue-Liang
2017-10-01
The relativistic Dirac equation in four-dimensional spacetime reveals a coherent relation between the dimensions of spacetime and the degrees of freedom of fermionic spinors. A massless Dirac fermion generates new symmetries corresponding to chirality spin and charge spin as well as conformal scaling transformations. With the introduction of intrinsic W-parity, a massless Dirac fermion can be treated as a Majorana-type or Weyl-type spinor in a six-dimensional spacetime that reflects the intrinsic quantum numbers of chirality spin. A generalized Dirac equation is obtained in the six-dimensional spacetime with a maximal symmetry. Based on the framework of gravitational quantum field theory proposed in Ref. [1] with the postulate of gauge invariance and coordinate independence, we arrive at a maximally symmetric gravitational gauge field theory for the massless Dirac fermion in six-dimensional spacetime. Such a theory is governed by the local spin gauge symmetry SP(1,5) and the global Poincaré symmetry P(1,5)=SO(1,5)⋉P 1,5 as well as the charge spin gauge symmetry SU(2). The theory leads to the prediction of doubly electrically charged bosons. A scalar field and conformal scaling gauge field are introduced to maintain both global and local conformal scaling symmetries. A generalized gravitational Dirac equation for the massless Dirac fermion is derived in the six-dimensional spacetime. The equations of motion for gauge fields are obtained with conserved currents in the presence of gravitational effects. The dynamics of the gauge-type gravifield as a Goldstone-like boson is shown to be governed by a conserved energy-momentum tensor, and its symmetric part provides a generalized Einstein equation of gravity. An alternative geometrical symmetry breaking mechanism for the mass generation of Dirac fermions is demonstrated. Supported by National Science Foundation of China (NSFC) (11690022, 11475237, 11121064) and Strategic Priority Research Program of the Chinese
FCNC Effects in a Minimal Theory of Fermion Masses
Buras, Andrzej J; Pokorski, Stefan; Ziegler, Robert
2011-01-01
As a minimal theory of fermion masses we extend the SM by heavy vectorlike fermions, with flavor-anarchical Yukawa couplings, that mix with chiral fermions such that small SM Yukawa couplings arise from small mixing angles. This model can be regarded as an effective description of the fermionic sector of a large class of existing flavor models and thus might serve as a useful reference frame for a further understanding of flavor hierarchies in the SM. Already such a minimal framework gives rise to FCNC effects through exchange of massive SM bosons whose couplings to the light fermions get modified by the mixing. We derive general formulae for these corrections and discuss the bounds on the heavy fermion masses. Particularly stringent bounds, in a few TeV range, come from the corrections to the Z couplings.
Untwisting twisted NJL2 kinks by a bare fermion mass
Thies, Michael
2017-12-01
Twisted kinks in the massless NJL2 model interpolate between two distinct vacua on the chiral circle. If one approaches the chiral limit from finite bare fermion masses m0, the vacuum is unique and twist cannot exist. This issue is studied analytically in the nonrelativistic limit, using a no-sea effective theory. We conclude that even in the massless limit, the interpretation of the twisted kink has to be revised. One has to attribute the fermion number of the valence state to the twisted kink. Fermion density is spread out over the whole space due to the massless pion field. The result can be pictured as a composite of a twisted kink (carrying energy, but no fermion number) and a partial winding of the chiral spiral (carrying fermion number, but no energy). This solves at the same time the puzzle of missing baryons with fermion number Nf
Direct manipulation of tool-like masters for controlling a master-slave surgical robotic system.
Zhang, Linan; Zhou, Ningxin; Wang, Shuxin
2014-12-01
Robotic-assisted minimally invasive surgery (MIS) can benefit both patients and surgeons. However, the learning curve for robotically assisted procedures can be long and the total system costs are high. Therefore, there is considerable interest in new methods and lower cost controllers for a surgical robotic system. In this study, a knife-master and a forceps-master, shaped similarly to a surgical knife and forceps, were developed as input devices for control of a master-slave surgical robotic system. In addition, a safety strategy was developed to eliminate the master-slave orientation difference and stabilize the surgical system. Master-slave tracking experiments and a ring-and-bar experiment showed that the safety tracking strategy could ensure that the robot system moved stably without any tremor in the tracking motion. Subjects could manipulate the surgical tool to achieve the master-slave operation with less training compared to a mechanical master. Direct manipulation of the small, light and low-cost surgical tools to control a robotic system is a possible operating mode. Surgeons can operate the robotic system in their own familiar way, without long training. The main potential safety issues can be solved by the proposed safety control strategy. Copyright © 2013 John Wiley & Sons, Ltd.
Sex pheromone of queens of the slave-making ant, Polyergus breviceps.
Greenberg, Les; Aliabadi, Ali; McElfresh, J Stephen; Topoff, Howard; Millar, Jocelyn G
2004-06-01
The sex attractant pheromone produced in mandibular glands of queens of the slave-making ant Polyergus breviceps has been identified as a blend of methyl 6-methylsalicylate and 3-ethyl-4-methylpentanol. In field trials, each compound alone was completely unattractive to males, whereas blends of the two compounds attracted hundreds of males within a couple of hours.
Master/slave: A better tool for Gabor filtering optical coherence tomography imaging instruments
DEFF Research Database (Denmark)
Cernat, Ramona; Bradu, Adrian; Israelsen, Niels Møller
2017-01-01
In this report, the benefits that the Master/Slave (MS) implementation of optical coherence tomography (OCT) can bring to a Gabor filtering (GF) imaging instrument are illustrated. The MS allows simultaneous display of three categories of images in one frame: multiple depth en-face OCT images, tw...
Analysis of Folk Tales for Prosocial Behavior among Slaves: Exploration of a Methodology.
Harrison, Algea Othella
The purpose of this paper is to discuss some of the methodological problems in using a content analysis of slave folk tales as a source for incidences of prosocial behaviors. Forty tales taken from four collections of black folktales will be included in this study. The categories for scoring prosocial behavior include cooperativeness, altruism,…
The Slave Trade and its Abolition in the Ikale-Yoruba Country, 1650 ...
African Journals Online (AJOL)
It has even been strongly suggested that an assessment of the impact of the trade and its abolition can only be realistic after weighing the evidence of detailed local ... this paper argues that the dynamics of Ikale pre-colonial economy and society cannot be properly understood without adequate reference to the slave trade.
Dalrymple-Smith, Angus
2017-01-01
The nineteenth century ‘commercial transition’ from export economies based on slaves to ones dominated by commodities like palm oil has been a central theme in West African history. However, most studies have tended to focus on the impact of the change and assumed that its causes were
Continuum-limit scaling of overlap fermions as valence quarks
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Herdoiza, Gregorio; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2009-10-15
We present the results of a mixed action approach, employing dynamical twisted mass fermions in the sea sector and overlap valence fermions, with the aim of testing the continuum limit scaling behaviour of physical quantities, taking the pion decay constant as an example. To render the computations practical, we impose for this purpose a fixed finite volume with lattice size L{approx}1.3 fm. We also briefly review the techniques we have used to deal with overlap fermions. (orig.)
Aspects of finite field-dependent symmetry in SU(2) Cho–Faddeev–Niemi decomposition
Energy Technology Data Exchange (ETDEWEB)
Upadhyay, Sudhaker, E-mail: sudhakerupadhyay@gmail.com
2013-11-25
In this Letter we consider SU(2) Yang–Mills theory analyzed in Cho–Faddeev–Niemi variables which remains invariant under local gauge transformations. The BRST symmetries of this theory are generalized by making the infinitesimal parameter finite and field-dependent. Further, we show that under appropriate choices of finite and field-dependent parameter, the gauge-fixing and ghost terms corresponding to Landau as well as maximal Abelian gauge for such Cho–Faddeev–Niemi decomposed theory appear naturally within functional integral through Jacobian calculation.
Topology in SU(2) lattice gauge theory and parallelization of functional magnetic resonance imaging
Energy Technology Data Exchange (ETDEWEB)
Solbrig, Stefan
2008-07-01
In this thesis, I discuss topological properties of quenched SU(2) lattice gauge fields. In particular, clusters of topological charge density exhibit a power-law. The exponent of that power-law can be used to validate models for lattice gauge fields. Instead of working with fixed cutoffs of the topological charge density, using the notion of a ''watermark'' is more convenient. Furthermore, I discuss how a parallel computer, originally designed for lattice gauge field simulations, can be used for functional magnetic resonance imaging. Multi parameter fits can be parallelized to achieve almost real-time evaluation of fMRI data. (orig.)
Thermodynamics of SU(2) mathcal{N} =2 supersymmetric Yang-Mills theory
Paik, Steve; Yaffe, Laurence G.
2010-01-01
The thermodynamics of four-dimensional SU(2) mathcal{N} =2 super-Yang-Mills theory is examined in both high and low temperature regimes. At low temperatures, compelling evidence is found for two distinct equilibrium states related by a spontaneously broken discrete R-symmetry. These equilibrium states exist because the quantum moduli space of the theory has two singular points where extra massless states appear. At high temperature, a unique R-symmetry-preserving equilibrium state is found. Discrepancies with previous results in the literature are explained.
Spherically symmetric classical solutions in SU(2) gauge theory with a Higgs field
Energy Technology Data Exchange (ETDEWEB)
Ratra, B.; Yaffe, L.G.
1988-04-21
A consistent ansatz for time dependent classical solutions in an SU(2) gauge theory with a doublet Higgs field is presented. The (3+1)-dimensional field equations are reduced to those of an effective (1+1)-dimensional theory. This ansatz describes solutions which travel between topologically distinct classical vacua of the non-abelian gauge theory. The real time version of these solutions describes the creation and decay of the unstable static 'sphaleron', the imaginary time version describes a euclidean instanton. (orig.)
Machine learning of explicit order parameters: From the Ising model to SU(2) lattice gauge theory
Wetzel, Sebastian J.; Scherzer, Manuel
2017-11-01
We present a solution to the problem of interpreting neural networks classifying phases of matter. We devise a procedure for reconstructing the decision function of an artificial neural network as a simple function of the input, provided the decision function is sufficiently symmetric. In this case one can easily deduce the quantity by which the neural network classifies the input. The method is applied to the Ising model and SU(2) lattice gauge theory. In both systems we deduce the explicit expressions of the order parameters from the decision functions of the neural networks. We assume no prior knowledge about the Hamiltonian or the order parameters except Monte Carlo-sampled configurations.
Representations of the deformed U(su(2)) and U(osp(1,2)) algebras
Bonatsos, Dennis; Kolokotronis, P; Lenis, D; Bonatsos, Dennis
1996-01-01
The polynomial deformations of the Witten extensions of the U(su(2)) and U(osp(1,2)) algebras are three generator algebras with normal ordering, admitting a two generator subalgebra. The modules and the representations of these algebras are based on the construction of Verma modules, which are quotient modules, generated by ideals of the original algebra. This construction unifies a large number of the known algebras under the same scheme. The finite dimensional representations show new features such as the multiplicity of representations of the same dimensionality, or the existence of finite dimensional representations only for some dimensions.
From decay to complete breaking: pulling the strings in SU(2) Yang-Mills theory.
Pepe, M; Wiese, U-J
2009-05-15
We study {2Q+1} strings connecting two static charges Q in (2+1)D SU(2) Yang-Mills theory. While the fundamental {2} string between two charges Q=1/2 is unbreakable, the adjoint {3} string connecting two charges Q=1 can break. When a {4} string is stretched beyond a critical length, it decays into a {2} string by gluon pair creation. When a {5} string is stretched, it first decays into a {3} string, which eventually breaks completely. The energy of the screened charges at the ends of a string is well described by a phenomenological constituent gluon model.
Monopoles in the Plaquette Formulation of the 3D SU(2) Lattice Gauge Theory
Borisenko, O; Boháčik, J
2011-01-01
Using a plaquette formulation for lattice gauge models we describe monopoles of the three dimensional SU(2) theory which appear as configurations in the complete axial gauge and violate the continuum Bianchi identity. Furthemore we derive a dual formulation for the Wilson loop in arbitrary representation and calculate the form of the interaction between generated electric flux and monopoles in the region of a weak coupling relevant for the continuum limit. The effective theory which controls the interaction is of the sine-Gordon type model. The string tension is calculated within the semiclassical approximation.
Hagedorn spectrum and thermodynamics of SU(2) and SU(3) Yang-Mills theories
Caselle, Michele; Panero, Marco
2015-01-01
We present a high-precision lattice calculation of the equation of state in the confining phase of SU(2) Yang-Mills theory. We show that the results are described very well by a gas of massive, non-interacting glueballs, provided one assumes an exponentially growing Hagedorn spectrum. The latter can be derived within an effective bosonic closed-string model, leading to a parameter-free theoretical prediction, which is in perfect agreement with our lattice results. Furthermore, when applied to SU(3) Yang-Mills theory, this effective model accurately describes the lattice results reported by Bors\\'anyi et al. in JHEP 07 (2012) 056.
Correlation functions of the energy-momentum tensor in SU(2) gauge theory at finite temperature
DEFF Research Database (Denmark)
Huebner, K.; Karsch, F.; Pica, Claudio
2008-01-01
We calculate correlation functions of the energy-momentum tensor in the vicinity of the deconfinement phase transition of (3+1)-dimensional SU(2) gauge theory and discuss their critical behavior in the vicinity of the second order deconfinement transition. We show that correlation functions...... of the trace of the energy momentum tensor diverge uniformly at the critical point in proportion to the specific heat singularity. Correlation functions of the pressure, on the other hand, stay finite at the critical point. We discuss the consequences of these findings for the analysis of transport...
An Exact SU(2) Symmetry and Persistent Spin Helix in a Spin-Orbit Coupled System
Energy Technology Data Exchange (ETDEWEB)
Bernevig, Andrei
2010-02-10
Spin-orbit coupled systems generally break the spin rotation symmetry. However, for a model with equal Rashba and Dresselhauss coupling constant (the ReD model), and for the [110] Dresselhauss model, a new type of SU(2) spin rotation symmetry is discovered. This symmetry is robust against spin-independent disorder and interactions, and is generated by operators whose wavevector depends on the coupling strength. It renders the spin lifetime infinite at this wavevector, giving rise to a Persistent Spin Helix (PSH). We obtain the spin fluctuation dynamics at, and away, from the symmetry point, and suggest experiments to observe the PSH.
An Exact SU(2) Symmetry and Persistent Spin Helix ina Spin-orbit Coupled System
Energy Technology Data Exchange (ETDEWEB)
Bernevig, B.A.; /Stanford U., Phys. Dept. /Santa Barbara, KITP; Orenstein, J.; /LBL, Berkeley /UC, Berkeley; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2007-01-22
Spin-orbit coupled systems generally break the spin rotation symmetry. However, for a model with equal Rashba and Dresselhauss coupling constant (the ReD model), and for the [110] Dresselhauss model, a new type of SU(2) spin rotation symmetry is discovered. This symmetry is robust against spin-independent disorder and interactions, and is generated by operators whose wavevector depends on the coupling strength. It renders the spin lifetime infinite at this wavevector, giving rise to a Persistent Spin Helix (PSH). We obtain the spin fluctuation dynamics at, and away, from the symmetry point, and suggest experiments to observe the PSH.
Directory of Open Access Journals (Sweden)
Guillermo García Fernández
2017-02-01
The result follows from strong antiscreening of the running coupling for those larger groups (with an appropriately small number of flavors together with scaling properties of the Dyson–Schwinger equation for the fermion mass.
Quantum Hall Effect of Massless Dirac Fermions and Free Fermions in Hofstadter's Butterfly
Yoshioka, Nobuyuki; Matsuura, Hiroyasu; Ogata, Masao
2016-06-01
We propose a new physical interpretation of the Diophantine equation of σxy for the Hofstadter problem. First, we divide the energy spectrum, or Hofstadter's butterfly, into smaller self-similar areas called "subcells", which were first introduced by Hofstadter to describe the recursive structure. We find that in the energy gaps between subcells, there are two ways to account for the quantization rule of σxy, that are consistent with the Diophantine equation: Landau quantization of (i) massless Dirac fermions or (ii) free fermions in Hofstadter's butterfly.
Fermion frontiers in vector lattice gauge theories: Proceedings. Volume 8
Energy Technology Data Exchange (ETDEWEB)
NONE
1998-11-01
The inclusion of fermions into simulations of lattice gauge theories is very difficult both theoretically and numerically. With the presence of Teraflops-scale computers for lattice gauge theory, the authors wanted a forum to discuss new approaches to lattice fermions. The workshop concentrated on approaches which are ripe for study on such large machines. Although lattice chiral fermions are vitally important to understand, there is not technique at hand which is viable on these Teraflops-scale machines for real-world problems. The discussion was therefore focused on recent developments and future prospects for QCD-like theories. For the well-known fermion formulations, the Aoki phase in Wilson fermions, novelties of U{sub A}(1) symmetry and the {eta}{prime} for staggered fermions and new approaches for simulating the determinant for Wilson fermions were discussed. The newer domain-wall fermion formulation was reviewed, with numerical results given by many speakers. The fermion proposal of Friedberg, Lee and Pang was introduced. They also were able to compare and contrast the dependence of QCD and QCD-like SUSY theories on the number of quark flavors. These proceedings consist of several transparencies and a summary page from each speaker. This should serve to outline the major points made in each talk.
Free fermions in two-dimensional Ising model (in English)
Plechko, V. N.
The two--dimensional (2D) Ising model is reviewed as a theory of free fermions on a lattice. The discussion includes the fermionization procedure based on the mirror--ordered factorization of the density matrix, Gaussian fermionic integral representation for partition function, the momentum--space analysis and Onsager's result, the effective continuum--limit field theories and the critical--point singularities. The emergence of long--range fermionic correlations in a nonzero magnetic field and the behaviour of the specific heat along the critical isotherm are commented. Attention is given to the choice of rational computational devices.
Black Slaves in Mamlūk Narratives: Representations of Transgression
Directory of Open Access Journals (Sweden)
Marmon, Shaun
2007-12-01
Full Text Available While a great deal of scholarly attention has been paid to the white military slaves and freedmen in the Mamluk Empire (1250- 1517, the black slaves (‘abīd have often been overlooked. In Egypt, Mamluk society, especially military society, was marked by a profound racial discourse that privileged white over black. This was by no means the only ethnic/racial categorization of people and groups, nor was it the only mechanism of privilege. But the definition of black slaves as the subaltern had social, economic and political ramifications that can not be ignored. Such definitions are especially evident in accounts of black slaves who are perceived to violate existing boundaries. My purpose in this paper is to explore the ways in which six Mamluk historians construct often mutually contradictory narratives of transgressive black slaves.
A pesar de que en los estudios sobre el Imperio Mameluco (1250-1517 se ha prestado gran atención a los esclavos blancos del ejército y a los libertos, se ha pasado por alto a los esclavos negros (‘abīd. En Egipto la sociedad mameluce, especialmente la sociedad militar, se caracterizaba por un discurso profundamente racial que privilegiaba lo blanco sobre lo negro. Ésta no era la única clasificación étnica/racial de gentes y grupos, ni el único mecanismo de establecer privilegios. Sin embargo, la definición de los esclavos negros como subalternos, tuvo consecuencias sociales, económicas y políticas que no pueden ser ignoradas. Estas definiciones son especialmente evidentes en los relatos sobre esclavos negros que se considera que han violado los límites existentes. Mi propósito en este artículo es explorar los modos con que seis historiadores mamelucos construyen las narraciones, a menudo contradictorias, de los esclavos negros transgresores.
Axion inflation with an SU(2) gauge field: detectable chiral gravity waves
Energy Technology Data Exchange (ETDEWEB)
Maleknejad, Azadeh [School of Physics, Institute for Research in Fundamental Sciences (IPM), P. Code. 19538-33511, Tehran (Iran, Islamic Republic of)
2016-07-20
We study a single field axion inflation model in the presence of an SU(2) gauge field with a small vev. In order to make the analysis as model-independent as possible, we consider an arbitrary potential for the axion that is able to support the slow-roll inflation. The gauge field is coupled to the axion with a Chern-Simons interaction (λ/f)F{sub μν}{sup a}F̃{sub a}{sup μν} where (λ/f)∼((O(10))/(M{sub pl})). It has a negligible effect on the background evolution, ((ρ{sub YM})/(M{sub pl}{sup 2}H{sup 2}))≲ϵ{sup 2}. However, its quantum fluctuations make a significant contribution to the cosmic perturbation. In particular, the gauge field has a spin-2 fluctuation which explicitly breaks the parity between the left- and right-handed polarization states. The chiral tensor modes are linearly coupled to the gravitational waves and lead to a circularly polarized tensor power spectrum comparable to the unpolarized vacuum power spectrum. Moreover, the scalar sector is modified by the linear scalar fluctuations of the gauge field. Since the spin-0 and spin-2 fluctuations of the SU(2) gauge field are independent, the gauge field can, at the same time, generate a detectable chiral gravitational wave signal and have a negligible contribution to the scalar fluctuations, in agreement with the current CMB observations.
Numerical Results for SU(4) and SU(2) Kondo Effect in Carbon Nanotubes
Martins, George; Busser, Carlos
2006-03-01
New numerical results are presented for the Kondo effect in Carbon Nanotube (CNT) quantum dots (QDs). As recently reported by P. Jarillo-Herrero et al. (Nature 434, 484 (2005)), the Kondo effect in CNTs presents an SU(4) symmetry, which arises from the entanglement of orbital and spin degrees of freedom. As the number of co-tunneling processes increases, thanks to the extra (orbital) degree of freedom, the Kondo temperature reaches a high value of TK=7.7K. Interesting considerations can be drawn regarding the change from SU(4) to SU(2) symmetries depending on the hopping matrix elements between the leads and the CNT QD. Our results will analyze the transition between the SU(4) and the so-called two-level SU(2) (2LSU(2)) Kondo regimes induced by the variation of the coupling of the QD to the leads. The effect of an external magnetic field along the tube direction will also be analyzed. Our results will be compared with available Numerical Renormalization Group (NRG) results by M-S Choi et al. (Phys. Rev. Lett. 95, 067204 (2005)). A comparison with the experimental results will be made to gauge the adequacy of the model and approximations made.
Klevers, Denis
2016-01-01
We give an explicit construction of a class of F-theory models with matter in the three-index symmetric (4) representation of SU(2). This matter is realized at codimension two loci in the F-theory base where the divisor carrying the gauge group is singular; the associated Weierstrass model does not have the form associated with a generic SU(2) Tate model. For 6D theories, the matter is localized at a triple point singularity of arithmetic genus g=3 in the curve supporting the SU(2) group. This is the first explicit realization of matter in F-theory in a representation corresponding to a genus contribution greater than one. The construction is realized by "unHiggsing" a model with a U(1) gauge factor under which there is matter with charge q=3. The resulting SU(2) models can be further unHiggsed to realize non-Abelian G_2xSU(2) models with more conventional matter content or SU(2)^3 models with trifundamental matter. The U(1) models used as the basis for this construction do not seem to have a Weierstrass real...
Silva, Wilson Araújo; Bortolini, Maria Cátira; Schneider, Maria Paula Cruz; Marrero, Andrea; Elion, Jacques; Krishnamoorthy, Rajagopal; Zago, Marco Antonio
2006-02-01
Seventy individuals from two African and four black Brazilian populations were studied for the first hypervariable segment of mtDNA. To delineate a more complete phylogeographic scenario of the African mtDNA haplogroups in Brazil and to provide additional information on the nature of the Atlantic slave trade, we analyzed our data together with previously published data. The results indicate different sources of African slaves for the four major Brazilian regions. In addition, the data revealed patterns that differ from those expected on the basis of historical registers, thus suggesting the role of ethnic sex differences in the slave trade.
Universal fermionic spectral functions from string theory.
Gauntlett, Jerome P; Sonner, Julian; Waldram, Daniel
2011-12-09
We carry out the first holographic calculation of a fermionic response function for a strongly coupled d=3 system with an explicit D=10 or D=11 supergravity dual. By considering the supersymmetry current, we obtain a universal result applicable to all d=3 N=2 SCFTs with such duals. Surprisingly, the spectral function does not exhibit a Fermi surface, despite the fact that the system is at finite charge density. We show that it has a phonino pole and at low frequencies there is a depletion of spectral weight with a power-law scaling which is governed by a locally quantum critical point.
Formation Time of a Fermion Pair Condensate
Zwierlein, M. W.; Schunck, C. H.; Stan, C. A.; Raupach, S. M. F.; Ketterle, W.
2004-01-01
The formation time of a condensate of fermionic atom pairs close to a Feshbach resonance was studied. This was done using a phase-shift method in which the delayed response of the many-body system to a modulation of the interaction strength was recorded. The observable was the fraction of condensed molecules in the cloud after a rapid magnetic field ramp across the Feshbach resonance. The measured response time was slow compared to the rapid ramp, which provides final proof that the molecular...
Exploring chiral dynamics with overlap fermions
Fukaya, Hidenori
2010-01-01
This talk presents a lattice study of spontaneous chiral symmetry breaking performed by the JLQCD and TWQCD collaborations with dynamical overlap fermions. Our lattice configurations are generated in a fixed topological sector. Since finite volume effects, partly due to the fixed global topology, are mainly induced by pion fields, the dependence on the lattice volume, topological charge and quark masses can be analytically predicted using chiral perturbation theory (ChPT). We find a good agreement of Dirac operator spectrum calculated on the lattice with the ChPT prediction including its finite size scalings, through which the chiral condensate is determined with good accuracy.
Some Improved Nonperturbative Bounds for Fermionic Expansions
Energy Technology Data Exchange (ETDEWEB)
Lohmann, Martin, E-mail: marlohmann@gmail.com [Universita di Roma Tre, Dipartimento di Matematica (Italy)
2016-06-15
We reconsider the Gram-Hadamard bound as it is used in constructive quantum field theory and many body physics to prove convergence of Fermionic perturbative expansions. Our approach uses a recursion for the amplitudes of the expansion, discovered in a model problem by Djokic (2013). It explains the standard way to bound the expansion from a new point of view, and for some of the amplitudes provides new bounds, which avoid the use of Fourier transform, and are therefore superior to the standard bounds for models like the cold interacting Fermi gas.
Density redistribution effects in fermionic optical lattices
Soni, Medha; Troyer, Matthias
2016-01-01
We simulate a one dimensional fermionic optical lattice to analyse heating due to non-adiabatic lattice loading. Our simulations reveal that, similar to the bosonic case, density redistribution effects are the major cause of heating in harmonic traps. We suggest protocols to modulate the local density distribution during the process of lattice loading, in order to reduce the excess energy. Our numerical results confirm that linear interpolation of the trapping potential and/or the interaction strength is an efficient method of doing so, bearing practical applications relevant to experiments.
Radburn, Nicholas
2015-01-01
In 1783 Scottish native John Tailyour arrived in Jamaica, where he hoped to make his fortune after a string of failed business ventures in North America. Fifteen years later he retired as a rich man. His newfound wealth came in large part from his career as a “Guinea factor,” a merchant who sold captive Africans from newly arrived slave ships. During his years as a Guinea factor, Tailyour sold 17,295 Africans into slavery through a traumatizing process that channeled captives to different buy...
Brazilian census sources and the ownership of slaves in the 1870s
Directory of Open Access Journals (Sweden)
Leite Marcondes, Renato
2011-04-01
Full Text Available There exists a significant group of sources of a census nature for the study of slavery in the 1870s. These sources derive mainly from the registration of slaves that was established by the Law of the Free Womb of 1871. In this article, we discuss the different ways of presenting registration information. We analyze a sample of the registered slave population, including 69 towns from different parts of the country that total a little over 112,000 slaves and 25, 000 slave holders. In addition to characterizing the demographic profile of the slaves that make up the sample, we verify the ownership of slaves.
Existe un conjunto expresivo de fuentes de carácter censal para el estudio de la esclavitud en la década de 1870 en Brasil. Estas fuentes derivan, principalmente, de la matrícula de los esclavos determinada por la Ley de Vientre Libre de 1871. En este artículo discutimos las diferentes formas de presentación de las informaciones de la matrícula. Analizamos una muestra de la población esclava matriculada, comprendiendo 69 localidades de diferentes partes del país que totalizan poco más de 112.000 esclavos y 25.000 esclavistas. Al caracterizar el perfil demográfico de los esclavos de nuestra muestra, comprobamos la propiedad de esclavos.
[pt] Existe um conjunto expressivo de fontes de caráter censitário para o estudo da escravidão da década de 1870. Estas fontes derivam, principalmente, da matrícula dos escravos determinada pela Lei do Ventre Livre de 1871. Neste artigo discutimos as diferentes formas de apresentação das informações da matrícula. Analisamos uma amostra da população escrava matriculada, compreendendo 69 localidades de diferentes partes do país que totalizam pouco mais de 112 mil escravos e 25 mil escravistas. Além caracterizar o perfil demográfico dos escravos da amostra, verificamos a posse de cativos.
Composite fermions a unified view of the quantum Hall regime
1998-01-01
One of the most exciting recent developments to have emerged from the quantum Hall effect is the subject of composite fermions. This important volume gives a self-contained, comprehensive description of the subject, including fundamentals, more advanced theoretical work, and results from experimental observations of composite fermions.
Calculation of CWKB envelope in boson and fermion productions
Indian Academy of Sciences (India)
We present the calculation of envelope of boson and of both low- and high- mass fermion production at the end of inflation when the coherently oscillating inflatons decay into bosons and fermions. We consider three different models of inflation and use CWKB technique to calculate the envelope to understand the structure ...
Calculation of CWKB envelope in boson and fermion productions
Indian Academy of Sciences (India)
Abstract. We present the calculation of envelope of boson and of both low- and high- mass fermion production at the end of inflation when the coherently oscillating inflatons decay into bosons and fermions. We consider three different models of inflation and use. CWKB technique to calculate the envelope to understand the ...
Nambu-Jona-Lasinio model with Wilson fermions
DEFF Research Database (Denmark)
Rantaharju, Jarno; Drach, Vincent; Pica, Claudio
2017-01-01
We present a lattice study of a Nambu-Jona-Lasinio (NJL) model using Wilson fermions. Four-fermion interactions are a natural part of several extensions of the Standard Model, appearing as a low-energy description of a more fundamental theory. In models of dynamical electroweak symmetry breaking ...
Scaling study of an improved fermion action on quenched lattices
Cho, Yong-Gwi; Noaki, Jun-Ichi; Kaneko, Takashi; Jüttner, Andreas; Tsang, Justus; Marinkovic, Marina
2014-01-01
We present scaling studies for heavy-quark observables calculated with an $O(a^2)$-improved fermion action on tree-level Symanzik improved gauge configurations. Lattices of $1/a = $ 2.0-3.8 GeV with an equal physical volume 1.6 fm are used. The results are compared with the standard domain-wall and naive Wilson fermions.
Landau levels of Majorana fermions in a spin liquid
Rachel, Stephan; Fritz, Lars; Vojta, Matthias
2016-01-01
Majorana fermions were originally proposed as elementary particles acting as their own antiparticles. In recent years, it has become clear that Majorana fermions can instead be realized in condensed-matter systems as emergent quasiparticles, a situation often accompanied by topological order. Here
Taste breaking in staggered fermions from random matrix theory
Energy Technology Data Exchange (ETDEWEB)
Osborna, James C
2004-03-01
We discuss the construction of a chiral random matrix model for staggered fermions. This model includes O(a{sup 2}) corrections to the continuum limit of staggered fermions and is related to the zero momentum limit of the Lee-Sharpe Lagrangian for staggered fermions. The naive construction based on a specific expansion in lattice spacing (a) of the Dirac matrix produces the term which gives the dominant contribution to the observed taste splitting in the pion masses. A more careful analysis can include extra terms which are also consistent with the symmetries of staggered fermions. Lastly I will mention possible uses of the model including studies of topology and fractional powers of the fermion determinant.
Extended Soliton Solutions in an Effective Action for SU(2 Yang-Mills Theory
Directory of Open Access Journals (Sweden)
Nobuyuki Sawado
2006-01-01
Full Text Available The Skyrme-Faddeev-Niemi (SFN model which is an O(3 σ model in three dimensional space up to fourth-order in the first derivative is regarded as a low-energy effective theory of SU(2 Yang-Mills theory. One can show from the Wilsonian renormalization group argument that the effective action of Yang-Mills theory recovers the SFN in the infrared region. However, the theory contains an additional fourth-order term which destabilizes the soliton solution. We apply the perturbative treatment to the second derivative term in order to exclude (or reduce the ill behavior of the original action and show that the SFN model with the second derivative term possesses soliton solutions.
More on the SU(2) deconfinement transition in the mixed action
Energy Technology Data Exchange (ETDEWEB)
Gavai, R.V. [Theoretical Physics Group, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Mathur, M. [Dipartimento di Fisica dell Universita and INFN, Piazza Torricelli 2 Pisa-56100 (Italy)
1997-07-01
We examine certain issues related to the universality of the SU(2) lattice gauge theory at nonzero temperatures. Using Monte Carlo simulations and strong coupling expansions, we study the behavior of the deconfinement transition in an extended coupling plane ({beta},{beta}{sub A}) around the tricritical point where the deconfinement transition changes from second to first order. Our numerical results on N{sub {tau}}=2,4,6,8 lattices show that the tricritical point first moves down towards the Wilson axis and then moves slowly upwards, if at all, as the lattice spacing is reduced. Lattices with very large N{sub {tau}} seem to be, therefore, necessary for the mixed action to exhibit the critical exponents of the three-dimensional Ising model for positive values of the adjoint coupling. {copyright} {ital 1997} {ital The American Physical Society}
Kramers-Wannier duality and worldline representation for the SU(2) principal chiral model
Gattringer, Christof; Göschl, Daniel; Marchis, Carlotta
2018-03-01
In this letter we explore different representations of the SU(2) principal chiral model on the lattice. We couple chemical potentials to two of the conserved charges to induce finite density. This leads to a complex action such that the conventional field representation cannot be used for a Monte Carlo simulation. Using the recently developed Abelian color flux approach we derive a new worldline representation where the partition sum has only real and positive weights, such that a Monte Carlo simulation is possible. In a second step we transform the model to new dual variables in the Kramers-Wannier (KW) sense, such that the constraints are automatically fulfilled, and we obtain a second representation free of the complex action problem. We implement exploratory Monte Carlo simulations for both, the worldline, as well as the KW-dual form, for cross-checking the two dualizations and a first assessment of their potential for dual simulations.
Rho meson decay width in SU(2) gauge theories with 2 fundamental flavours
Janowski, Tadeusz; Pica, Claudio
2016-01-01
SU(2) gauge theories with two quark flavours in the fundamental representation are among the most promising theories of composite dynamics describing the electroweak sector. Three out of five Goldstone bosons in these models become the longitudinal components of the W and Z bosons giving them mass. Like in QCD, we expect a spectrum of excitations which appear as resonances in vector boson scattering, in particular the vector resonance corresponding to the rho-meson in QCD. In this talk I will present the preliminary results of the first calculation of the rho-meson decay width in this theory, which is analogous to rho to two pions decay calculation in QCD. The results presented were calculated in a moving frame with total momentum (0,0,1) on two ensembles. Future plans include using 3 moving frames on a larger set of ensembles to extract the resonance parameters more reliably and also take the chiral and continuum limits.
Study of shear viscosity of SU(2)-gluodynamics within lattice simulation
Energy Technology Data Exchange (ETDEWEB)
Astrakhantsev, N.Yu. [Institute for Theoretical and Experimental Physics,Moscow, 117218 (Russian Federation); Moscow Institute of Physics and Technology,Dolgoprudny, 141700 (Russian Federation); Braguta, V.V. [Institute for Theoretical and Experimental Physics,Moscow, 117218 (Russian Federation); Institute for High Energy Physics NRC “Kurchatov Institute”,Protvino, 142281 Russian Federation (Russian Federation); Far Eastern Federal University, School of Biomedicine,Vladivostok, 690950 (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute),Kashirskoe highway, 31, Moscow, 115409 (Russian Federation); Kotov, A.Yu. [Institute for Theoretical and Experimental Physics,Moscow, 117218 (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute),Kashirskoe highway, 31, Moscow, 115409 (Russian Federation)
2015-09-14
This paper is devoted to the study of two-point correlation function of the energy-momentum tensor 〈T{sub 12}T{sub 12}〉 for SU(2)-gluodynamics within lattice simulation of QCD. Using multilevel algorithm we carried out the measurement of the correlation function at the temperature T/T{sub c}≃1.2. It is shown that lattice data can be described by spectral functions which interpolate between hydrodynamics at low frequencies and asymptotic freedom at high frequencies. The results of the study of spectral functions allowed us to estimate the ratio of shear viscosity to the entropy density η/s=0.134±0.057.
Effective geometric phases and topological transitions in SO(3) and SU(2) rotations.
Saarikoski, Henri; Baltanás, José Pablo; Vázquez-Lozano, J Enrique; Nitta, Junsaku; Frustaglia, Diego
2016-04-27
We address the development of geometric phases in classical and quantum magnetic moments (spin-1/2) precessing in an external magnetic field. We show that nonadiabatic dynamics lead to a topological phase transition determined by a change in the driving field topology. The transition is associated with an effective geometric phase which is identified from the paths of the magnetic moments in a spherical geometry. The topological transition presents close similarities between SO(3) and SU(2) cases but features differences in, e.g. the adiabatic limits of the geometric phases, being 2π and π in the classical and the quantum case, respectively. We discuss possible experiments where the effective geometric phase would be observable.
Scaling properties of SU(2) gauge theory with mixed fundamental-adjoint action
Rinaldi, Enrico; Lucini, Biagio; Patella, Agostino; Rago, Antonio
2012-01-01
We study the phase diagram of the SU(2) lattice gauge theory with fundamental-adjoint Wilson plaquette action. We confirm the presence of a first order bulk phase transition and we estimate the location of its end-point in the bare parameter space. If this point is second order, the theory is one of the simplest realizations of a lattice gauge theory admitting a continuum limit at finite bare couplings. All the relevant gauge observables are monitored in the vicinity of the fixed point with very good control over finite-size effects. The scaling properties of the low-lying glueball spectrum are studied while approaching the end-point in a controlled manner.
Couplings in D(2,1;α) superconformal mechanics from the SU(2) perspective
Energy Technology Data Exchange (ETDEWEB)
Galajinsky, Anton [Laboratory of Mathematical Physics, Tomsk Polytechnic University,Lenin Ave. 30, 634050 Tomsk (Russian Federation)
2017-03-09
Dynamical realizations of the most general N=4 superconformal group in one dimension D(2,1;α) are reconsidered from the perspective of the R-symmetry subgroup SU(2). It is shown that any realization of the R-symmetry subalgebra in some phase space can be extended to a representation of the Lie superalgebra corresponding to D(2,1;α). Novel couplings of arbitrary number of supermultiplets of the type (1,4,3) and (0,4,4) to a single supermultiplet of either the type (3,4,1), or (4,4,0) are constructed. D(2,1;α) superconformal mechanics describing superparticles propagating near the horizon of the extreme Reissner-Nordström-AdS-dS black hole in four and five dimensions is considered. The parameter α is linked to the cosmological constant.
Drinfeld Doubles for Finite Subgroups of SU(2 and SU(3 Lie Groups
Directory of Open Access Journals (Sweden)
Robert Coquereaux
2013-05-01
Full Text Available Drinfeld doubles of finite subgroups of SU(2 and SU(3 are investigated in detail. Their modular data – S, T and fusion matrices – are computed explicitly, and illustrated by means of fusion graphs. This allows us to reexamine certain identities on these tensor product or fusion multiplicities under conjugation of representations that had been discussed in our recent paper [J. Phys. A: Math. Theor. 44 (2011, 295208, 26 pages], proved to hold for simple and affine Lie algebras, and found to be generally wrong for finite groups. It is shown here that these identities fail also in general for Drinfeld doubles, indicating that modularity of the fusion category is not the decisive feature. Along the way, we collect many data on these Drinfeld doubles which are interesting for their own sake and maybe also in a relation with the theory of orbifolds in conformal field theory.
Supersymmetric Extension of Non-Hermitian su(2 Hamiltonian and Supercoherent States
Directory of Open Access Journals (Sweden)
Omar Cherbal
2010-12-01
Full Text Available A new class of non-Hermitian Hamiltonians with real spectrum, which are written as a real linear combination of su(2 generators in the form H=ωJ_3+αJ_−+βJ_+, α≠β, is analyzed. The metrics which allows the transition to the equivalent Hermitian Hamiltonian is established. A pseudo-Hermitian supersymmetic extension of such Hamiltonians is performed. They correspond to the pseudo-Hermitian supersymmetric systems of the boson-phermion oscillators. We extend the supercoherent states formalism to such supersymmetic systems via the pseudo-unitary supersymmetric displacement operator method. The constructed family of these supercoherent states consists of two dual subfamilies that form a bi-overcomplete and bi-normal system in the boson-phermion Fock space. The states of each subfamily are eigenvectors of the boson annihilation operator and of one of the two phermion lowering operators.
Phase diagram of SU(2) with 2 flavors of dynamical adjoint quarks
Catterall, Simon; Sannino, Francesco; Schneible, Joe
2008-01-01
We report on numerical simulations of SU(2) lattice gauge theory with two flavors of light dynamical quarks in the adjoint of the gauge group. The dynamics of this theory is thought to be very different from QCD -- the theory exhibiting conformal or near conformal behavior in the infrared. We make a high resolution survey of the phase diagram of this model in the plane of the bare coupling and quark mass on lattices of size 8^3 \\times 16. Our simulations reveal a line of first order phase transitions extending from beta=0 to beta=beta_c \\sim 2.0. For beta > beta_c the line is no longer first order but continues as the locus of minimum meson mass. For beta > 2.0 we observe the critical pion and rho masses to be light, independent of bare coupling and approximately degenerate. We discuss possible interpretations of these observations and corresponding continuum limits.
Progress gauge symmetry breaking in SU(6) x SU(2) sub R model
Hayashi, T; Matsuda, M; Matsuoka, T
2003-01-01
In the SU(6) x SU(2) sub R string-inspired model, we describe the evolution of the couplings and the masses down from the string scale M sub s using the renormalization group equations and minimize the effective potential. This model possesses the flavor symmetry, including the binary dihedral group D tilde sub 4. We show that the scalar mass squared of the gauge non-singlet matter field possibly becomes negative slightly below the string scale. As a consequence, the precocious radiative breaking of the gauge symmetry down to the standard model gauge group can be realized. In the present model, the large Yukawa coupling, which plays an important role in the symmetry breaking, is identical to the colored Higgs coupling related to the longevity of the proton. (author)
Hagedorn spectrum and thermodynamics of SU(2) and SU(3) Yang-Mills theories
Energy Technology Data Exchange (ETDEWEB)
Caselle, Michele; Nada, Alessandro; Panero, Marco [Department of Physics, University of Turin & INFN,Via Pietro Giuria 1, I-10125 Turin (Italy)
2015-07-27
We present a high-precision lattice calculation of the equation of state in the confining phase of SU(2) Yang-Mills theory. We show that the results are described very well by a gas of massive, non-interacting glueballs, provided one assumes an exponentially growing Hagedorn spectrum. The latter can be derived within an effective bosonic closed-string model, leading to a parameter-free theoretical prediction, which is in perfect agreement with our lattice results. Furthermore, when applied to SU(3) Yang-Mills theory, this effective model accurately describes the lattice results reported by Borsányi et al. in http://dx.doi.org/10.1007/JHEP07(2012)056.
Search for Majorana fermions in topological superconductors.
Energy Technology Data Exchange (ETDEWEB)
Pan, Wei [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Shi, Xiaoyan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hawkins, Samuel D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Klem, John Frederick [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-10-01
The goal of this project is to search for Majorana fermions (a new quantum particle) in a topological superconductor (a new quantum matter achieved in a topological insulator proximitized by an s-wave superconductor). Majorana fermions (MFs) are electron-like particles that are their own anti-particles. MFs are shown to obey non-Abelian statistics and, thus, can be harnessed to make a fault-resistant topological quantum computer. With the arrival of topological insulators, novel schemes to create MFs have been proposed in hybrid systems by combining a topological insulator with a conventional superconductor. In this LDRD project, we will follow the theoretical proposals to search for MFs in one-dimensional (1D) topological superconductors. 1D topological superconductor will be created inside of a quantum point contact (with the metal pinch-off gates made of conventional s-wave superconductors such as niobium) in a two-dimensional topological insulator (such as inverted type-II InAs/GaSb heterostructure).
Fermion perturbations in string theory black holes
Energy Technology Data Exchange (ETDEWEB)
Piedra, Owen Pavel Fernandez; De Oliveira, Jeferson, E-mail: opavel@ucf.edu.cu, E-mail: jeferson@fma.if.usp.br [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, 05315-970, Sao Paulo (Brazil)
2011-04-21
In this paper we study fermion perturbations in four-dimensional black holes of string theory, obtained either from a non-extreme configuration of three intersecting five-branes with a boost along the common string or from a non-extreme intersecting system of two two-branes and two five-branes. The Dirac equation for the massless neutrino field, after conformal re-scaling of the metric, is written as a wave equation suitable to study the time evolution of the perturbation. We perform a numerical integration of the evolution equation, and with the aid of Prony fitting of the time-domain profile, we calculate the complex frequencies that dominate the quasinormal ringing stage, and also determine these quantities by the semi-analytical sixth-order WKB method. We also find numerically the decay factor of fermion fields at very late times, and show that the falloff is identical to those showing for massless fields in other four-dimensional black hole spacetimes.
Fermion perturbations in string theory black holes
Pavel Fernández Piedra, Owen; de Oliveira, Jeferson
2011-04-01
In this paper we study fermion perturbations in four-dimensional black holes of string theory, obtained either from a non-extreme configuration of three intersecting five-branes with a boost along the common string or from a non-extreme intersecting system of two two-branes and two five-branes. The Dirac equation for the massless neutrino field, after conformal re-scaling of the metric, is written as a wave equation suitable to study the time evolution of the perturbation. We perform a numerical integration of the evolution equation, and with the aid of Prony fitting of the time-domain profile, we calculate the complex frequencies that dominate the quasinormal ringing stage, and also determine these quantities by the semi-analytical sixth-order WKB method. We also find numerically the decay factor of fermion fields at very late times, and show that the falloff is identical to those showing for massless fields in other four-dimensional black hole spacetimes.
Monotop signature from a fermionic top partner
Gonçalves, Dorival; Kong, Kyoungchul; Sakurai, Kazuki; Takeuchi, Michihisa
2018-01-01
We investigate monotop signatures arising from phenomenological models of fermionic top partners, which are degenerate in mass and decay into a bosonic dark matter candidate, either spin 0 or spin 1. Such a model provides a monotop signature as a smoking gun, while conventional searches with t t ¯ + missing transverse momentum are limited. Two such scenarios, (i) a phenomenological third generation extradimensional model with excited top and electroweak sectors, and (ii) a model where only a top partner and a dark matter particle are added to the standard model, are studied in the degenerate mass regime. We find that in the case of extra dimension a number of different processes give rise to effectively the same monotop final state, and a great gain can be obtained in the sensitivity for this channel. We show that the monotop search can explore top-partner masses up to 630 and 300 GeV for the third generation extradimensional model and the minimal fermionic top-partner model, respectively, at the high luminosity LHC.
Analytic fermionic Green's functions from holography
Gubser, Steven S.; Ren, Jie
2012-08-01
We find exact, analytic solutions of the Dirac equation for a charged, massless fermion in the background of a charged, dilatonic black hole in AdS5. The black hole descends from type IIB supergravity, where it describes D3-branes with equal angular momenta in two of the three independent planes of rotation orthogonal to the world-volume. The Green’s function near the Fermi surface for a strongly coupled fermionic system can be extracted holographically from an exact solution of the Dirac equation at zero frequency but nonzero momentum. There can be several Fermi momenta, and they take the form kF=q-n-1/2 (in units of the chemical potential), where q is the charge of the spinor, and n is a non-negative integer that labels the Fermi surfaces. Much as for holographic Fermi surfaces based on the Reissner-Nordström-AdS5 solution, the dispersion relation of the excitations near the Fermi surface is determined by the geometry close to the horizon, and one can obtain Fermi liquid, marginal Fermi liquid, and non-Fermi liquid behaviors depending on the value of kF.
SU(2)CMB at high redshifts and the value of H0
Hahn, Steffen; Hofmann, Ralf
2017-07-01
We investigate a high-z cosmological model to compute the comoving sound horizon rs at baryon-velocity freeze-out towards the end of hydrogen recombination. This model assumes a replacement of the conventional cosmic microwave background (CMB) photon gas by deconfining SU(2) Yang-Mills thermodynamics, three flavours of massless neutrinos (Nν = 3) and a purely baryonic matter sector [no cold dark-matter (CDM)]. The according SU(2) temperature-redshift relation of the CMB is contrasted with recent measurements appealing to the thermal Sunyaev-Zel'dovich effect and CMB-photon absorption by molecular rotation bands or atomic hyperfine levels. Relying on a realistic simulation of the ionization history throughout recombination, we obtain z* = 1693.55 ± 6.98 and zdrag = 1812.66 ± 7.01. Due to considerable widths of the visibility functions in the solutions to the associated Boltzmann hierarchy and Euler equation, we conclude that z* and zdrag overestimate the redshifts for the respective photon and baryon-velocity freeze-out. Realistic decoupling values turn out to be zlf,* = 1554.89 ± 5.18 and zlf, drag = 1659.30 ± 5.48. With rs(zlf, drag) = (137.19 ± 0.45) Mpc and the essentially model independent extraction of rsH0 = constant from low-z data in Bernal, Verde & Riess, we obtain a good match with the value H0 = (73.24 ± 1.74) km s-1 Mpc-1 extracted in Riess et al. by appealing to Cepheid-calibrated Type Ia supernovae, new parallax measurements, stronger constraints on the Hubble flow and a refined computation of distance to NGC 4258 from maser data. We briefly comment on a possible interpolation of our high-z model, invoking percolated and unpercolated U(1) topological solitons of a Planck-scale axion field, to the phenomenologically successful low-z ΛCDM cosmology.
THE CONSEQUENCES OF CRUELTY THE ESCALATION OF SERVANT AND SLAVE ABUSE, 1750-1780
Directory of Open Access Journals (Sweden)
Michael V. Kennedy
2004-01-01
Full Text Available As the need for reliable labor sources increased in British North America during the 18th century, there was a rise in the numbers of servants and slaves imported. In the Mid-Atlantic region, dependence on various types of bound labor was characteristic of commercial and industrial expansion. The two major wars of the 18” century, however, the Seven Years War and the War for American Independence, created unusual opportunities for both servants and slaves to seek their freedom through flight. The common reaction by masters after the mid-1750s was to increase their controls over bound workers and impose more severe punishments for any misdemeanors, particularly attempts to run away. The results were a radical change in the treatment of indentured servants, and the promotion of the very reaction that masters were trying to prevent—increased flight.
Reaction Force/Torque Sensing in a Master-Slave Robot System without Mechanical Sensors
Directory of Open Access Journals (Sweden)
Kyoko Shibata
2010-07-01
Full Text Available In human-robot cooperative control systems, force feedback is often necessary in order to achieve high precision and high stability. Usually, traditional robot assistant systems implement force feedback using force/torque sensors. However, it is difficult to directly mount a mechanical force sensor on some working terminals, such as in applications of minimally invasive robotic surgery, micromanipulation, or in working environments exposed to radiation or high temperature. We propose a novel force sensing mechanism for implementing force feedback in a master-slave robot system with no mechanical sensors. The system consists of two identical electro-motors with the master motor powering the slave motor to interact with the environment. A bimanual coordinated training platform using the new force sensing mechanism was developed and the system was verified in experiments. Results confirm that the proposed mechanism is capable of achieving bilateral force sensing and mirror-image movements of two terminals in two reverse control directions.
Queen sex pheromone of the slave-making ant, Polyergus breviceps.
Greenberg, Les; Tröger, Armin G; Francke, Wittko; McElfresh, J Steven; Topoff, Howard; Aliabadi, Ali; Millar, Jocelyn G
2007-05-01
Workers of the slave-making ant, Polyergus breviceps, raid nests of Formica ants and return with Formica pupae that mature into worker ants in the slave-makers' colony. These Formica workers then tend the Polyergus brood, workers, and reproductives. During raids in the mating season, winged virgin Polyergus queens accompany the workers in the raiding columns. During the raid, the virgin queens release a pheromone that attracts males that quickly mate with the queens. We report the identification, synthesis, and bioassay of the sex attractant pheromone of the queens as an approximately 1:6 ratio of (R)-3-ethyl-4-methylpentan-1-ol and methyl 6-methylsalicylate. The ants produce exclusively the (R)-enantiomer of the alcohol, and the (S)-enantiomer has no biological activity, neither inhibiting nor increasing attraction to blends of methyl 6-methylsalicylate with the (R)-enantiomer.
Fabrication of bridge transportation system for dual arm master-slave servo manipulator
Energy Technology Data Exchange (ETDEWEB)
Ha, Chan Ho; Lee, Dong Cheol; Kim, Hae Jin [Moojin Keeyeon, Gwangju (Korea, Republic of)
2010-05-15
A bridge transportation system for dual arm master-slave servo manipulator consists of an overhead transportation system for slave manipulator and a wall transportation system for master manipulator. This work includes fabrication of bridge(x-direction), trolley(y-direction), telescopic tube(z-direction), and rotation assembly for the overhead transportation system, and tube and rotation assembly for the wall transportation system. Moojin Co., Ltd. checked the drawings provided by KAERI and undertook the fabrication after minor revisions. Also, assembling procedures were addressed before tasks and used as assembling guides. After completion of the fabrication, inspection and performance tests were carried out and showed the bridge transportation system could fulfill its own functions
Cooperative Path Planning and Constraints Analysis for Master-Slave Industrial Robots
Directory of Open Access Journals (Sweden)
Yahui Gan
2012-09-01
Full Text Available A strategy of cooperative path planning for a master-slave multiple robot system is presented in this paper. The path planning method is based on motion constraints between the end-effectors of cooperative robots. Cooperation motions have been classified into three types by relative motions between end-effectors of master and slave robots, which is concurrent cooperation, coupled synchronous cooperation and combined synchronous cooperation. Based on this classification, position /orientation constraints and joint velocity constraints are explored in-depth here. In order to validate the path planning method and the theoretical developments in motion constraints analysis, representative experiments based on two industrial robots, Motoman VA1400 and HP20, are provided at the end of the paper. The experimental results have proved both the effectiveness of the path planning method and the correctness of the constraints analysis.
Food for thought: interpreting the parable of the loyal and wise slave ...
African Journals Online (AJOL)
The parable of the loyal and wise slave appears in Q 12:42-46 (Matt. 24:45-51; Luke 12:42-46). I have argued elsewhere that verses 45-46 were added to verses 42-44 by Q's main redactor. If so, only Q 12:42-44 originally appeared in Kloppenborg's formative stratum, or Q1. The purpose of the present article is to ascertain ...
food for thought: interpreting the parable of the loyal and wise slave
African Journals Online (AJOL)
and grammatical overlap between the two versions to justify its place in the Sayings Gospel Q (Dodd 1958:158; .... On a figurative level, the same Greek word (οἰκετεία) could also denote a “slave population” .... grammar and word order of two specific phrases in Q 12:42-46 are almost identical to two corresponding phrases ...
Control design and implementation of a novel master-slave surgery robot system, MicroHand A.
Sang, Hongqiang; Wang, Shuxin; Li, Jianmin; He, Chao; Zhang, Lin'an; Wang, Xiaofei
2011-09-01
Compared with conventional minimally invasive surgery and open surgery, robotic-assisted minimally invasive surgery can overcome or eliminate drawbacks caused by operator restrictions, motion limitation by the trocar and the image system, such as fatigue, trembling, low precision, constrained degree-of-freedom, poor hand-eye coordination and restricted surgical vision. In this paper, a novel partly tendon-driven master-slave robot system is proposed to assist minimally invasive surgery and a master-slave control architecture is developed for abdominal surgical operations. A novel master-slave surgery robot system named MicroHand A has been developed. A kinematic analysis of master and slave manipulators was conducted, based on screw theory and vector loop equation. The relationships of the tendon-driven multi-DOF surgical instrument among Cartesian space, actuator space and joint space were derived for control purposes. The control system architecture of the MicroHand A was designed with intuitive motion control and motion scaling control. Llewellyn's absolute stability criterion and the transparency of the one-DOF master-slave system are also analysed. Intuitive motion control under dissimilar kinematics in master-slave manipulations and motion scaling control were accomplished to solve absonant hand-eye coordination, kinematic dissimilarity and workspace mismatch of master-slave manipulator problems. A series of tests and animal experiments were carried out to evaluate system performance. The experimental results demonstrate that the system could accomplish intuitive motion control and motion scaling control, and that the control system is stable and reliable. The experiments performed on the MicroHand A robotic system yielded expected control results. The system satisfies the requirements of minimally invasive surgery. Intuitive motion control and motion scaling control under different kinematics for the master and slave have been implemented. Copyright © 2011
Adler, Stephen L.
2017-07-01
We continue our study of Coleman-Weinberg symmetry breaking induced by a third rank antisymmetric tensor scalar, in the context of the SU(8) model (Adler 2014 Int. J. Mod. Phys. A 29 1450130) we proposed earlier. We focus in this paper on qualitative features that will determine whether the model can make contact with the observed particle spectrum. We discuss the mechanism for giving the spin \\frac{3}{2} field a mass by the BEH mechanism, and analyze the remaining massless spin \\frac{1}{2} fermions, the global chiral symmetries, and the running couplings after symmetry breaking. We note that the smallest gluon mass matrix eigenvalue has an eigenvector suggestive of U(1) B-L , and conjecture that the theory runs to an infrared fixed point at which there is a massless gluon with 3 to -1 ratios in generator components. Assuming this, we discuss a mechanism for making contact with the standard model, based on a conjectured asymmetric breaking of Sp(4) to SU(2) subgroups, one of which is the electroweak SU(2), and the other of which is a ‘technicolor’ group that binds the original SU(8) model fermions, which play the role of ‘preons’, into composites. Quarks can emerge as 5 preon composites and leptons as 3 preon composites, with consequent stability of the proton against decay to a single lepton plus a meson. A composite Higgs boson can emerge as a two preon composite. Since anomaly matching for the relevant conserved global symmetry current is not obeyed by three fermion families, emergence of three composite families requires formation of a Goldstone boson with quantum numbers matching this current, which can be a light dark matter candidate.
Design of an integrated master-slave robotic system for minimally invasive surgery.
Li, Jianmin; Zhou, Ningxin; Wang, Shuxin; Gao, Yuanqian; Liu, Dongchun
2012-03-01
Minimally invasive surgery (MIS) robots are commonly used in hospitals and medical centres. However, currently available robotic systems are very complicated and huge, greatly raising system costs and the requirements of operating rooms. These disadvantages have become the major impediments to the expansion of MIS robots. An integrated MIS robotic system is proposed based on the analysis of advantages and disadvantages of different MIS robots. In the proposed system, the master manipulators, slave manipulators, image display device and control system have been designed as a whole. Modular design is adopted for the control system for easy maintenance and upgrade. The kinematic relations between the master and the slave are also investigated and embedded in software to realize intuitive movements of hand and instrument. Finally, animal experiments were designed to test the effectiveness of the robot. The robot realizes natural hand-eye movements between the master and the slave to facilitate MIS operations. The experimental results show that the robot can realize similar functions to those of current commercialized robots. The integrated design simplifies the robotic system and facilitates use of the robot. Compared with the commercialized robots, the proposed MIS robot achieves similar functions and features but with a smaller size and less weight. Copyright © 2011 John Wiley & Sons, Ltd.
Directory of Open Access Journals (Sweden)
Ahmet Kuzu
2014-01-01
Full Text Available This paper proposes two novel master-slave configurations that provide improvements in both control and communication aspects of teleoperation systems to achieve an overall improved performance in position control. The proposed novel master-slave configurations integrate modular control and communication approaches, consisting of a delay regulator to address problems related to variable network delay common to such systems, and a model tracking control that runs on the slave side for the compensation of uncertainties and model mismatch on the slave side. One of the configurations uses a sliding mode observer and the other one uses a modified Smith predictor scheme on the master side to ensure position transparency between the master and slave, while reference tracking of the slave is ensured by a proportional-differentiator type controller in both configurations. Experiments conducted for the networked position control of a single-link arm under system uncertainties and randomly varying network delays demonstrate significant performance improvements with both configurations over the past literature.
Link fermions and dynamically correlated paths for lattice gauge theory
Energy Technology Data Exchange (ETDEWEB)
Brower, R.C. (Harvard Univ., Cambridge, MA (USA). Lyman Lab. of Physics); Giles, R.C. (Massachusetts Inst. of Tech., Cambridge (USA). Lab. for Nuclear Science); Kessler, D.A. (Los Alamos National Lab., NM (USA). Theoretical Div.); Maturana, G. (California Univ., Santa Cruz (USA). Physics Dept.)
1983-07-07
The calculation of fermion bound states in lattice QCD is discussed from the point of view of the Feynman path integral and the corresponding lattice 'path sum' representation of the fermion propagator. Path sum methods which correlate the trajectories of valence fermion and antifermion constituents of a meson bound state are presented. The resultant Monte Carlo algorithm for the meson propagator samples predominantly those configurations which are expected to be most important for a tightly bound system. Relative to other techniques, this procedure anticipates cancellations due to gauge field averaging, and in addition, allows a more detailed examination of the bound state wavefunction. Inspired by the fermionic path representation of the 2D Ising model, we also introduce a new class of lattice fermion actions with nearest neighbor interactions between Grassman variables associated with links. These link fermions are a simple generalization of Wilson's fermions. They have an additional corner weight parameter which can be adjusted to obtain a much improved dispersion relation for moderate and parge lattice momenta.
Majorana fermions in condensed matter: An outlook
Ma, Ning
2017-05-01
The Majorana fermions (MFs) were firstly envisioned by Majorana in 1937 as fundamental constituents of nature, whereas experimentally thus far unobserved in the realm of fundamental particles. More recent studies have revealed that the MFs could occur in condensed matter physics as emergent quasiparticle excitations in effectively spinless p-wave topological superconductors (TS). They are shown to behave as effectively fractionalized anyons following non-Abelian braiding statistics rather than the usual Fermi or Bose exchange statistics. This extraordinary property would directly lead to a perpetually coherent and fault tolerant topological quantum computation in 2D systems. Currently the experiments searching for MFs on much more special systems are ongoing and the investigations of MFs' behavior in TS-coupled systems are also been actively pursued, with the goal of deeply understanding the fundamental physics of fractional statistics in nature, and further paving more feasible ways toward a working universal topological quantum computer.
Machine Learning Phases of Strongly Correlated Fermions
Ch'ng, Kelvin; Carrasquilla, Juan; Melko, Roger G.; Khatami, Ehsan
2017-07-01
Machine learning offers an unprecedented perspective for the problem of classifying phases in condensed matter physics. We employ neural-network machine learning techniques to distinguish finite-temperature phases of the strongly correlated fermions on cubic lattices. We show that a three-dimensional convolutional network trained on auxiliary field configurations produced by quantum Monte Carlo simulations of the Hubbard model can correctly predict the magnetic phase diagram of the model at the average density of one (half filling). We then use the network, trained at half filling, to explore the trend in the transition temperature as the system is doped away from half filling. This transfer learning approach predicts that the instability to the magnetic phase extends to at least 5% doping in this region. Our results pave the way for other machine learning applications in correlated quantum many-body systems.
Standard model fermions and N=8 supergravity
Energy Technology Data Exchange (ETDEWEB)
Nicolai, Hermann [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Muehlenberg 1, Potsdam-Golm (Germany)
2016-07-01
In a scheme originally proposed by Gell-Mann, and subsequently shown to be realized at the SU(3) x U(1) stationary point of maximal gauged SO(8) supergravity, the 48 spin-1/2 fermions of the theory remaining after the removal of eight Goldstinos can be identified with the 48 quarks and leptons (including right-chiral neutrinos) of the Standard model, provided one identifies the residual SU(3) with the diagonal subgroup of the color group SU(3){sub c} and a family symmetry SU(3){sub f}. However, there remained a systematic mismatch in the electric charges by a spurion charge of ± 1/6. We here identify the ''missing'' U(1) that rectifies this mismatch, and that takes a surprisingly simple, though unexpected form, and show how it is related to the conjectured R symmetry K(E10) of M Theory.
Local entropy of a nonequilibrium fermion system
Stafford, Charles A.; Shastry, Abhay
2017-03-01
The local entropy of a nonequilibrium system of independent fermions is investigated and analyzed in the context of the laws of thermodynamics. It is shown that the local temperature and chemical potential can only be expressed in terms of derivatives of the local entropy for linear deviations from local equilibrium. The first law of thermodynamics is shown to lead to an inequality, not equality, for the change in the local entropy as the nonequilibrium state of the system is changed. The maximum entropy principle (second law of thermodynamics) is proven: a nonequilibrium distribution has a local entropy less than or equal to a local equilibrium distribution satisfying the same constraints. It is shown that the local entropy of the system tends to zero when the local temperature tends to zero, consistent with the third law of thermodynamics.
Charge carrier holes and Majorana fermions
Liang, Jingcheng; Lyanda-Geller, Yuli
2017-05-01
Understanding Luttinger holes in low dimensions is crucial for numerous spin-dependent phenomena and nanotechnology. In particular, hole quantum wires that are proximity coupled to a superconductor is a promising system for the observation of Majorana fermions. Earlier treatments of confined Luttinger holes ignored a mutual transformation of heavy and light holes at the heteroboundaries. We derive the effective hole Hamiltonian in the ground state. The mutual transformation of holes is crucial for Zeeman and spin-orbit coupling, and results in several spin-orbit terms linear in momentum in hole quantum wires. We discuss the criterion for realizing Majorana modes in charge carrier hole systems. GaAs or InSb hole wires shall exhibit stronger topological superconducting pairing, and provide additional opportunities for its control compared to InSb electron systems.
A two-dimensional Dirac fermion microscope
Bøggild, Peter; Caridad, José M.; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads
2017-06-01
The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots.
Fermionic functional integrals and the renormalization group
Feldman, Joel; Trubowitz, Eugene
2002-01-01
This book, written by well-known experts in the field, offers a concise summary of one of the latest and most significant developments in the theoretical analysis of quantum field theory. The renormalization group is the name given to a technique for analyzing the qualitative behavior of a class of physical systems by iterating a map on the vector space of interactions for the class. In a typical nonrigorous application of this technique, one assumes, based on one's physical intuition, that only a certain finite dimensional subspace (usually of dimension three or less) is important. The material in this book concerns a technique for justifying this approximation in a broad class of fermionic models used in condensed matter and high energy physics. This volume is based on the Aisenstadt Lectures given by Joel Feldman at the Centre de Recherches Mathematiques (Montreal, Canada). It is suitable for graduate students and research mathematicians interested in mathematical physics. Included are many problems and so...
Highly Anisotropic Dirac Fermions in Square Graphynes.
Zhang, L Z; Wang, Z F; Wang, Zhiming M; Du, S X; Gao, H-J; Liu, Feng
2015-08-06
We predict a family of 2D carbon (C) allotropes, square graphynes (S-graphynes) that exhibit highly anisotropic Dirac fermions, using first-principle calculations within density functional theory. They have a square unit-cell containing two sizes of square C rings. The equal-energy contour of their 3D band structure shows a crescent shape, and the Dirac crescent has varying Fermi velocities from 0.6 × 10(5) to 7.2 × 10(5) m/s along different k directions. Near the Fermi level, the Dirac crescent can be nicely expressed by an extended 2D Dirac model Hamiltonian. Furthermore, tight-binding band fitting reveals that the Dirac crescent originates from the next-nearest-neighbor interactions between C atoms. S-graphynes may be used to build new 2D electronic devices taking advantages of their highly directional charge transport.
Controlling interactions in ultracold fermionic ytterbium-173
Höfer, Moritz; Riegger, Luis; Hofrichter, Chrisitian; Rio Fernandes, Diogo; Bloch, Immanuel; Fölling, Simon
2016-05-01
The possibility to tune the interactions of ultracold atomic gases with an external magnetic field has become a vital tool for many quantum gas experiments. For fermionic ytterbium-173 both the 1 S0 ground state and 3 P0 metastable state have vanishing angular momentum J = 0 and therefore no magnetic Feshbach resonances are expected. Here we report on the discovery of a novel type of Feshbach resonance, which was predicted to exist due to orbital-mixing interactions. It occurs universally for all hyperfine-state combinations of ytterbium-173 and is located at experimentally accessible magnetic fields. The scattering properties are characterized by inter-orbital cross-thermalization measurements in the bulk as well as high resolution clock-line spectroscopy in a three-dimensional lattice. Furthermore, we study the dynamics of a strongly interacting two-orbital quantum gas in two dimensions.
Interdimensional effects in systems with quasirelativistic fermions
Zulkoskey, A. C.; Dick, R.; Tanaka, K.
2017-07-01
We examine the Green function and the density of states for fermions moving in three-dimensional Dirac materials with interfaces which affect the propagation properties of particles. Motivation for our research comes from interest in materials that exhibit quasirelativistic dispersion relations. By modifying Dirac-type contributions to the Hamiltonian in an interface we are able to calculate the Green function and the density of states. The density of states inside the interface exhibits interpolating behavior between two and three dimensions, with two-dimensional behavior at high energies and three-dimensional behavior at low energies, provided that the shift in the mass parameter in the interface is small. We also discuss the impact of the interpolating density of states on optical absorption in Dirac materials with a two-dimensional substructure.
New scheme for braiding Majorana fermions
Wu, Long-Hua; Liang, Qi-Feng; Hu, Xiao
2014-01-01
Non-Abelian statistics can be achieved by exchanging two vortices in topological superconductors with each grabbing a Majorana fermion (MF) as zero-energy quasi-particle at the cores. However, in experiments it is difficult to manipulate vortices. In the present work, we propose a way to braid MFs without moving vortices. The only operation required in the present scheme is to turn on and off local gate voltages, which liberates a MF from its original host vortex and transports it along the prepared track. We solve the time-dependent Bogoliubov–de Gennes equation numerically, and confirm that the MFs are protected provided the switching of gate voltages for exchanging MFs are adiabatic, which takes only several nano seconds given reasonable material parameters. By monitoring the time evolution of MF wave-functions, we show that non-Abelian statistics is achieved. PMID:27877725
Machine Learning Phases of Strongly Correlated Fermions
Directory of Open Access Journals (Sweden)
Kelvin Ch’ng
2017-08-01
Full Text Available Machine learning offers an unprecedented perspective for the problem of classifying phases in condensed matter physics. We employ neural-network machine learning techniques to distinguish finite-temperature phases of the strongly correlated fermions on cubic lattices. We show that a three-dimensional convolutional network trained on auxiliary field configurations produced by quantum Monte Carlo simulations of the Hubbard model can correctly predict the magnetic phase diagram of the model at the average density of one (half filling. We then use the network, trained at half filling, to explore the trend in the transition temperature as the system is doped away from half filling. This transfer learning approach predicts that the instability to the magnetic phase extends to at least 5% doping in this region. Our results pave the way for other machine learning applications in correlated quantum many-body systems.
Bootstrapping 3D fermions with global symmetries
Iliesiu, Luca; Kos, Filip; Poland, David; Pufu, Silviu S.; Simmons-Duffin, David
2018-01-01
We study the conformal bootstrap for 4-point functions of fermions 〈 ψ i ψ j ψ k ψ ℓ 〉 in parity-preserving 3d CFTs, where ψ i transforms as a vector under an O( N ) global symmetry. We compute bounds on scaling dimensions and central charges, finding features in our bounds that appear to coincide with the O( N ) symmetric Gross-Neveu-Yukawa fixed points. Our computations are in perfect agreement with the 1 /N expansion at large N and allow us to make nontrivial predictions at small N . For values of N for which the Gross-Neveu-Yukawa universality classes are relevant to condensed-matter systems, we compare our results to previous analytic and numerical results.
D-brane Inspired Fermion Mass Textures
Leontaris, G K
2010-01-01
In this paper, the issues of the quark mass hierarchies and the Cabbibo Kobayashi Maskawa mixing are analyzed in a class of intersecting D-brane configurations with Standard Model gauge symmetry. The relevant mass matrices are constructed taking into account the constraints imposed by extra abelian symmetries and anomaly cancelation conditions. Possible mass generating mechanisms including perturbative as well as non-perturbative effects are discussed and specific patterns of mass textures are found characterized by the hierarchies of the scales where the various sources contribute. It is argued that the Cholesky decomposition of the mass matrices is the most appropriate way to determine the properties of these fermion mass patterns, while the associated triangular mass matrix form provides a unified description of all phenomenologically equivalent symmetric and non-symmetric mass matrices. An elegant analytic formula is derived for the Cholesky triangular form of the mass matrices where the entries are given...
A two-dimensional Dirac fermion microscope.
Bøggild, Peter; Caridad, José M; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads
2017-06-09
The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots.
Experimental signatures of split fermions in extra dimensions
Energy Technology Data Exchange (ETDEWEB)
Grossman, Y.
2000-01-21
The smallness and hierarchy of the fermion parameters could be explained in theories with extra dimensions where doublets and singlets are localized at slightly separated points. Scattering cross sections for collisions of such fermions vanish exponentially at energies high enough to probe the separation distance. This is because the separation puts a lower bound on the attainable impact parameter in the collision. The NLC, and in particular the combination of the e{sup +}e{sup {minus}} and e{sup {minus}}e{sup {minus}} modes, can probe this scenario, even if the inverse fermion separation is of order tens of TeVs.
Collective Interference of Composite Two-Fermion Bosons
DEFF Research Database (Denmark)
Tichy, Malte; Bouvrie, Peter Alexander; Mølmer, Klaus
2012-01-01
The composite character of two-fermion bosons manifests itself in the interference of many composites as a deviation from the ideal bosonic behavior. A state of many composite bosons can be represented as a superposition of different numbers of perfect bosons and fermions, which allows us...... to provide the full Hong–Ou–Mandel-like counting statistics of interfering composites. Our theory quantitatively relates the deviation from the ideal bosonic interference pattern to the entanglement of the fermions within a single composite boson....
The Nambu Jona-Lasinio model with Wilson fermions
Rantaharju, Jarno
2017-01-01
We present a lattice study of a Nambu Jona-Lasinio (NJL) model using Wilson fermions. Four fermion interactions are a natural part of several extensions of the Standard Model, appearing as a low energy description of a more fundamental theory. In models of dynamical electroweak symmetry breaking they are used to endow the Standard Model fermions with masses. In infrared conformal models these interaction, when sufficiently strong, can alter the dynamics of the fixed point, turning the theory into a (near) conformal model with desirable features for model building. As a first step toward the nonperturbative study of these models, we study the phase space of the ungauged NJL model.
Boundary effects and gapped dispersion in rotating fermionic matter
Directory of Open Access Journals (Sweden)
Shu Ebihara
2017-01-01
Full Text Available We discuss the importance of boundary effects on fermionic matter in a rotating frame. By explicit calculations at zero temperature we show that the scalar condensate of fermion and anti-fermion cannot be modified by the rotation once the boundary condition is properly implemented. The situation is qualitatively changed at finite temperature and/or in the presence of a sufficiently strong magnetic field that supersedes the boundary effects. Therefore, to establish an interpretation of the rotation as an effective chemical potential, it is crucial to consider further environmental effects such as the finite temperature and magnetic field.
Gapped fermions in top-down holographic superconductors
DeWolfe, Oliver; Gubser, Steven S.; Henriksson, Oscar; Rosen, Christopher
2017-04-01
We use holography to compute spectral functions of certain fermionic operators in three different finite-density, zero-temperature states of Aharony-Bergman-Jafferis-Maldacena (ABJM) theory with a broken U (1 ) symmetry. In each of the three states, dual to previously studied domain wall solutions of four-dimensional gauged supergravity, we find that the fermionic operators have gapped spectra. In one case the gap can be traced to the small charge of the fermions, while in the other cases it is due to a particular interaction that mixes particles and holes.
A possible connection between massive fermions and dark energy
Energy Technology Data Exchange (ETDEWEB)
Goldman, Terrance [Los Alamos National Laboratory; Stephenson, G J [UNM; Alsing, P M [UNM; Mckellar, B H J [UNIV OF MELBOURNE
2009-01-01
In a dense cloud of massive fermions interacting by exchange of a light scalar field, the effective mass of the fermion can become negligibly small. As the cloud expands, the effective mass and the total energy density eventually increase with decreasing density. In this regime, the pressure-density relation can approximate that required for dark energy. They apply this phenomenon to the expansion of the Universe with a very light scalar field and infer relations between the parameters available and cosmological observations. Majorana neutrinos at a mass that may have been recently determined, and fermions such as the Lightest Supersymmetric Particle (LSP) may both be consistent with current observations of dark energy.
Contributions in anomalous fermion momenta of neutral vector boson in plane-wave field
Klimenko, E Y
2002-01-01
The contributions of the neutral vector boson to the anomalous magnetic and electric momenta of the polarized fermion moving in the plane-wave electromagnetic field are considered in this paper. The contributions are divided by the fermion spin polarization states, which makes it possible to investigate the important problem on the contributions to the fermion anomalous momenta, coming from the the fermion transition to the intermediate state spin-nonflip or spin flip of fermion
On the composition of an arbitrary collection of SU(2) spins: an enumerative combinatoric approach
Gyamfi, J. A.; Barone, V.
2018-03-01
The whole enterprise of spin compositions can be recast as simple enumerative combinatoric problems. We show here that enumerative combinatorics (Stanley 2011 Enumerative Combinatorics (Cambridge Studies in Advanced Mathematics vol 1) (Cambridge: Cambridge University Press)) is a natural setting for spin composition, and easily leads to very general analytic formulae—many of which hitherto not present in the literature. Based on it, we propose three general methods for computing spin multiplicities; namely, (1) the multi-restricted composition, (2) the generalized binomial and (3) the generating function methods. Symmetric and anti-symmetric compositions of SU(2) spins are also discussed, using generating functions. Of particular importance is the observation that while the common Clebsch–Gordan decomposition—which considers the spins as distinguishable—is related to integer compositions, the symmetric and anti-symmetric compositions (where one considers the spins as indistinguishable) are obtained considering integer partitions. The integers in question here are none other than the occupation numbers of the Holstein–Primakoff bosons. The pervasiveness of q-analogues in our approach is a testament to the fundamental role they play in spin compositions. In the appendix, some new results in the power series representation of Gaussian polynomials (or q-binomial coefficients)—relevant to symmetric and antisymmetric compositions—are presented.
A nonlinear deformed su(2) algebra with a two-colour quasitriangular Hopf structure
Bonatsos, Dennis; Kolokotronis, P; Ludu, A; Quesne, C
1996-01-01
Nonlinear deformations of the enveloping algebra of su(2), involving two arbitrary functions of J_0 and generalizing the Witten algebra, were introduced some time ago by Delbecq and Quesne. In the present paper, the problem of endowing some of them with a Hopf algebraic structure is addressed by studying in detail a specific example, referred to as ${\\cal A}^+_q(1)$. This algebra is shown to possess two series of (N+1)-dimensional unitary irreducible representations, where N=0, 1, 2, .... To allow the coupling of any two such representations, a generalization of the standard Hopf axioms is proposed by proceeding in two steps. In the first one, a variant and extension of the deforming functional technique is introduced: variant because a map between two deformed algebras, su_q(2) and ${\\cal A}^+_q(1)$, is considered instead of a map between a Lie algebra and a deformed one, and extension because use is made of a two-valued functional, whose inverse is singular. As a result, the Hopf structure of su_q(2) is car...
CKM and PMNS Mixing Matrices from Discrete Subgroups of SU(2
Directory of Open Access Journals (Sweden)
Potter F.
2014-07-01
Full Text Available One of the greatest challenges in particle physics is to determine the first principles origin of the quark and lepton mixing matrices CKM and PMNS that relate the flavor states to the mass states. This first principles derivation of both the PMNS and CKM matrices utilizes quaternion generators of the three discrete (i.e., finite binary rotational subgroups of SU(2 called [3,3,2], [4,3,2], and [5,3,2] for three lepton families in R 3 and four related discrete binary rotational subgroups [3,3,3], [4,3,3], [3,4,3], and [5,3,3] represented by four quark families in R 4 . The traditional 3 3 CKM matrix is extracted as a submatrix of the 4 4 CKM4 matrix. The predicted fourth family of quarks has not been discovered yet. If these two additional quarks exist, there is the possibility that the Standard Model lagrangian may apply all the way down to the Planck scale.
The GL(1 vertical stroke 1)-symplectic fermion correspondence
Energy Technology Data Exchange (ETDEWEB)
Creutzig, Thomas; Roenne, Peter B.
2008-12-15
In this note we prove a correspondence between the Wess-Zumino-Novikov-Witten model of the Lie supergroup GL(1 vertical stroke 1) and a free model consisting of two scalars and a pair of symplectic fermions. This model was discussed earlier by LeClair. Vertex operators for the symplectic fermions include twist fields, and correlation functions of GL(1 vertical stroke 1) agree with the known results for the scalars and symplectic fermions. We perform a detailed study of boundary states for symplectic fermions and apply them to branes in GL(1 vertical stroke 1). This allows us to compute new amplitudes of strings stretching between branes of different types and confirming Cardy's condition. (orig.)
Skyrmion Superfluidity in Two-Dimensional Interacting Fermionic Systems.
Palumbo, Giandomenico; Cirio, Mauro
2015-06-17
In this article we describe a multi-layered honeycomb lattice model of interacting fermions which supports a new kind of parity-preserving skyrmion superfluidity. We derive the low-energy field theory describing a non-BCS fermionic superfluid phase by means of functional fermionization. Such effective theory is a new kind of non-linear sigma model, which we call double skyrmion model. In the bi-layer case, the quasiparticles of the system (skyrmions) have bosonic statistics and replace the Cooper-pairs role. Moreover, we show that the model is also equivalent to a Maxwell-BF theory, which naturally establishes an effective Meissner effect without requiring a breaking of the gauge symmetry. Finally, we map effective superfluidity effects to identities among fermionic observables for the lattice model. This provides a signature of our theoretical skyrmion superfluidy that can be detected in a possible implementation of the lattice model in a real quantum system.
Quasi-relativistic fermions and dynamical flavour oscillations
Alexandre, Jean; Mavromatos, Nick E.
2014-01-01
We introduce new Lorentz-symmetry violating kinematics for a four-fermion interaction model, where dynamical mass generation is allowed, irrespectively of the strength of the coupling. In addition, these kinematics lead to a quasi-relativistic dispersion relation, in the sense that it is relativistic in both the infrared and the ultraviolet, but not in an intermediate regime, characterized by the mass $M$. For two fermions, we show that a flavour-mixing mass matrix is generated dynamically, and the Lorentz symmetric limit $M\\to\\infty$ leads to two free relativistic fermions, with flavour oscillations. This model, valid for either Dirac or Majorana fermions, can describe any set of phenomenological values for the eigen masses and the mixing angle.
Diffusion in higher dimensional SYK model with complex fermions
Cai, Wenhe; Ge, Xian-Hui; Yang, Guo-Hong
2018-01-01
We construct a new higher dimensional SYK model with complex fermions on bipartite lattices. As an extension of the original zero-dimensional SYK model, we focus on the one-dimension case, and similar Hamiltonian can be obtained in higher dimensions. This model has a conserved U(1) fermion number Q and a conjugate chemical potential μ. We evaluate the thermal and charge diffusion constants via large q expansion at low temperature limit. The results show that the diffusivity depends on the ratio of free Majorana fermions to Majorana fermions with SYK interactions. The transport properties and the butterfly velocity are accordingly calculated at low temperature. The specific heat and the thermal conductivity are proportional to the temperature. The electrical resistivity also has a linear temperature dependence term.
Strongly-interacting mirror fermions at the LHC
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Triantaphyllou George
2017-01-01
Full Text Available The introduction of mirror fermions corresponding to an interchange of leftwith right-handed fermion quantum numbers of the Standard Model can lead to a model according to which the BEH mechanism is just an effective manifestation of a more fundamental theory while the recently-discovered Higgs-like particle is composite. This is achieved by a non-abelian gauge symmetry encompassing three mirror-fermion families strongly coupled at energies near 1 TeV. The corresponding non-perturbative dynamics lead to dynamical mirror-fermion masses between 0.14 - 1.2 TeV. Furthermore, one expects the formation of composite states, i.e. “mirror mesons”, with masses between 0.1 and 3 TeV. The number and properties of the resulting new degrees of freedom lead to a rich and interesting phenomenology, part of which is analyzed in the present work.
A Comparative Study on q-Deformed Fermion Oscillators
Algin, Abdullah
2011-05-01
In this paper, the algebras, representations, and thermostatistics of four types of fermionic q-oscillator models, called fermionic Newton (FN), Chaichian-Kulish-Ng (CKN), Parthasarathy-Viswanathan-Chaichian (PVC), Viswanathan-Parthasarathy-Jagannathan-Chaichian (VPJC), are discussed. Similarities and differences among the properties of these models are revealed. Particular emphasis is given to the VPJC-oscillators model so that its Fock space representation is analyzed in detail. Possible physical applications of these models are concisely pointed out.
Quenched scalar-meson correlator with domain wall fermions
Energy Technology Data Exchange (ETDEWEB)
Prelovsek, S.; Orginos, K
2003-05-01
We study the q-barq singlet and non-singlet scalar-meson masses using domain wall fermions and the quenched approximation. The singlet mass is found to be smaller than the non-singlet mass and indicates that the lowest singlet meson state could be lighter than 1 GeV. The two-point functions for very small quark masses are compared with expectations from the small-volume chiral perturbation theory and the presence of fermionic zero modes.
Quadratic fermionic interactions yield effective Hamiltonians for adiabatic quantum computing
O'Hara, Michael J.; O'Leary, Dianne P.
2008-01-01
Polynomially-large ground-state energy gaps are rare in many-body quantum systems, but useful for adiabatic quantum computing. We show analytically that the gap is generically polynomially-large for quadratic fermionic Hamiltonians. We then prove that adiabatic quantum computing can realize the ground states of Hamiltonians with certain random interactions, as well as the ground states of one, two, and three-dimensional fermionic interaction lattices, in polynomial time. Finally, we use the J...
Spectral properties of four-time fermionic Green's functions
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A.M. Shvaika
2016-09-01
Full Text Available The spectral relations for the four-time fermionic Green's functions are derived in the most general case. The terms which correspond to the zero-frequency anomalies, known before only for the bosonic Green's functions, are separated and their connection with the second cumulants of the Boltzmann distribution function is elucidated. The high-frequency expansions of the four-time fermionic Green's functions are provided for different directions in the frequency space.
Grassmann phase space methods for fermions. II. Field theory
Energy Technology Data Exchange (ETDEWEB)
Dalton, B.J., E-mail: bdalton@swin.edu.au [Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne, Victoria 3122 (Australia); Jeffers, J. [Department of Physics, University of Strathclyde, Glasgow G4ONG (United Kingdom); Barnett, S.M. [School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)
2017-02-15
In both quantum optics and cold atom physics, the behaviour of bosonic photons and atoms is often treated using phase space methods, where mode annihilation and creation operators are represented by c-number phase space variables, with the density operator equivalent to a distribution function of these variables. The anti-commutation rules for fermion annihilation, creation operators suggests the possibility of using anti-commuting Grassmann variables to represent these operators. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of Grassmann phase space methods in quantum-atom optics to treat fermionic systems is rather rare, though fermion coherent states using Grassmann variables are widely used in particle physics. This paper presents a phase space theory for fermion systems based on distribution functionals, which replace the density operator and involve Grassmann fields representing anti-commuting fermion field annihilation, creation operators. It is an extension of a previous phase space theory paper for fermions (Paper I) based on separate modes, in which the density operator is replaced by a distribution function depending on Grassmann phase space variables which represent the mode annihilation and creation operators. This further development of the theory is important for the situation when large numbers of fermions are involved, resulting in too many modes to treat separately. Here Grassmann fields, distribution functionals, functional Fokker–Planck equations and Ito stochastic field equations are involved. Typical applications to a trapped Fermi gas of interacting spin 1/2 fermionic atoms and to multi-component Fermi gases with non-zero range interactions are presented, showing that the Ito stochastic field equations are local in these cases. For the spin 1/2 case we also show how simple solutions can be obtained both for the untrapped case and for an optical lattice trapping potential.
Competing forces in five-dimensional fermion condensation
Yoon, Jongmin; Peskin, Michael E.
2017-12-01
We study fermion condensation in the Randall-Sundrum background as a setting for composite Higgs models. We formalize the computation of the Coleman-Weinberg potential and present a simple, general formula. Using this tool, we study the competition of fermion multiplets with different boundary conditions, to find conditions for creating a little hierarchy with the Higgs field expectation value much smaller than the intrinsic Randall-Sundrum mass scale.
A gauge field theory of fermionic continuous-spin particles
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X. Bekaert
2016-09-01
Full Text Available In this letter, we suggest a local covariant action for a gauge field theory of fermionic Continuous-Spin Particles (CSPs. The action is invariant under gauge transformations without any constraint on both the gauge field and the gauge transformation parameter. The Fang–Fronsdal equations for a tower of massless fields with all half-integer spins arise as a particular limit of the equation of motion of fermionic CSPs.
The Infrared behaviour of the gluon propagator in SU(2) and SU(3) without lattice Gribov copies
Alexandrou, C; Follana, E; De Forcrand, Ph
2000-01-01
We present lattice results for the gluon propagator for SU(2) and SU(3) in the Laplacian gauge which avoids lattice Gribov copies. In SU(3) we compare with the most recent lattice calculation in Landau gauge and with various approximate solutions of the Dyson Schwinger equations (DSE).
Fermion localization on a warped Conifold-like defect
Energy Technology Data Exchange (ETDEWEB)
Dantas, Davi Monteiro; Silva, Jose Euclides Gomes da; Almeida, Carlos Alberto Santos de [Universidade Federal do Ceara, Fortaleza, CE (Brazil)
2013-07-01
Full text: In this work we investigate the location of the spinor field in a six-dimensional braneword. Build the background as warped product between a 3+1 brane and the transverse space generated by a circle from a resolved conifold. This background can be interpreted as a smooth case of a string-like defect, where the resolution parameter is responsible for this smooth and the removal of the singularity at the origin. We conclude that free massless fermions are found only on the negative tension of brane for this geometry. So interactions are necessary for finding these modes on brane positive tension. This work coupling fermions with a gauge field and track which condition the angular component of this coupling must satisfy in order confine this mode. The resolution parameter became essential for normalization and well-defined of fermionic zero mode. For the massive modes (Kaluza-Klein modes), has obtained a Schroedinger-like equation for each chiral mode. Qualitative analysis of this equation allowed to find a volcano potential only for left-handed fermions, whose the depth of the well and barrier height is controlled by the parameter resolution. This result justifies the existence of fermions with only one type of chirality confined in our brane. The potential obtained for massive fermions with right-handed chirality indicates that these modes would find in a ring around our brane. (author)
The Genomic Legacy of the Transatlantic Slave Trade in the Yungas Valley of Bolivia.
Heinz, Tanja; Cárdenas, Jorge Mario; Álvarez-Iglesias, Vanesa; Pardo-Seco, Jacobo; Gómez-Carballa, Alberto; Santos, Carla; Taboada-Echalar, Patricia; Martinón-Torres, Federico; Salas, Antonio
2015-01-01
During the period of the Transatlantic Slave Trade (TAST) some enslaved Africans were forced to move to Upper Peru (nowadays Bolivia). At first they were sent to Potosí, but later to the tropical Yungas valley where the Spanish colonizers established a so-called "hacienda system" that was based on slave labor, including African-descendants. Due to their isolation, very little attention has been paid so far to 'Afro-Bolivian' communities either within the research field of TAST or in genetic population studies. In this study, a total of 105 individuals from the Yungas were sequenced for their mitochondrial DNA (mtDNA) control region, and mitogenomes were obtained for a selected subset of these samples. We also genotyped 46 Ancestry Informative Markers (AIM) in order to investigate continental ancestry at the autosomal level. In addition, Y-chromosome STR and SNP data for a subset of the same individuals was also available from the literature. The data indicate that the partitioning of mtDNA ancestry in the Yungas differs significantly from that in the rest of the country: 81% Native American, 18% African, and 1% European. Interestingly, the great majority of 'Afro-descendant' mtDNA haplotypes in the Yungas (84%) concentrates in the locality of Tocaña. This high proportion of African ancestry in the Tocaña is also manifested in the Y-chromosome (44%) and in the autosomes (56%). In sharp contrast with previous studies on the TAST, the ancestry of about 1/3 of the 'Afro-Bolivian' mtDNA haplotypes can be traced back to East and South East Africa, which may be at least partially explained by the Arab slave trade connected to the TAST.
The Genomic Legacy of the Transatlantic Slave Trade in the Yungas Valley of Bolivia
Cárdenas, Jorge Mario; Álvarez-Iglesias, Vanesa; Pardo-Seco, Jacobo; Gómez-Carballa, Alberto; Santos, Carla; Taboada-Echalar, Patricia; Martinón-Torres, Federico
2015-01-01
During the period of the Transatlantic Slave Trade (TAST) some enslaved Africans were forced to move to Upper Peru (nowadays Bolivia). At first they were sent to Potosí, but later to the tropical Yungas valley where the Spanish colonizers established a so-called “hacienda system” that was based on slave labor, including African-descendants. Due to their isolation, very little attention has been paid so far to ‘Afro-Bolivian’ communities either within the research field of TAST or in genetic population studies. In this study, a total of 105 individuals from the Yungas were sequenced for their mitochondrial DNA (mtDNA) control region, and mitogenomes were obtained for a selected subset of these samples. We also genotyped 46 Ancestry Informative Markers (AIM) in order to investigate continental ancestry at the autosomal level. In addition, Y-chromosome STR and SNP data for a subset of the same individuals was also available from the literature. The data indicate that the partitioning of mtDNA ancestry in the Yungas differs significantly from that in the rest of the country: 81% Native American, 18% African, and 1% European. Interestingly, the great majority of ‘Afro-descendant’ mtDNA haplotypes in the Yungas (84%) concentrates in the locality of Tocaña. This high proportion of African ancestry in the Tocaña is also manifested in the Y-chromosome (44%) and in the autosomes (56%). In sharp contrast with previous studies on the TAST, the ancestry of about 1/3 of the ‘Afro-Bolivian’ mtDNA haplotypes can be traced back to East and South East Africa, which may be at least partially explained by the Arab slave trade connected to the TAST. PMID:26263179
Constructing the rights and duties of slave-owners as socio-historic context of the New Testament
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H. Goede
2009-07-01
Full Text Available This article aims to construct the rights and duties of slave- owners in antiquity as part of the socio-historical context of the New Testament. In order to achieve this aim, the primary sources referring to Greek, Roman and Jewish law of slavery will first be described. Three aspects of the law of slavery, namely legal definitions of freedom and slavery, the legal status of slaves, and the rights of slave-owners are investigated in Greek, Roman and Jewish law. Relevant texts from these sources are then identified, analysed and interpreted. The re- sults of this process of analysis and interpretation are used to construct the legal context within which the exhortations directed at slave-owners in the New Testament should be read. We submit that Jewish law provided a sound alternative legal and religious context to the writers of the New Testament addressing Christian slave-owners. This alternative context functioned as a counterweight to the strict legal contexts pro- vided by Greek and Roman law.
Chronotopes in Harriet Jacobs's Incidents in the Life of a Slave Girl
Holmgren Troy, Maria
2016-01-01
This article employs Bakhtin’s concept of the chronotope to examine the interrelatedness of different places, temporalities, characterization, and values in Harriet Jacobs’s Incidents in the Life of a Slave Girl. Focusing on the complex interactions of four chronotopes—Dr. Flint’s house, the provincial town, the grandmother’s house, and the garret—the article yields a deeper understanding of how Jacobs critiques antebellum American society and, at the same time, constructs the grandmother’s h...
Slave Boson Theory of Orbital Differentiation with Crystal Field Effects: Application to UO2
Lanatà, Nicola; Yao, Yongxin; Deng, Xiaoyu; Dobrosavljević, Vladimir; Kotliar, Gabriel
2017-03-01
We derive an exact operatorial reformulation of the rotational invariant slave boson method, and we apply it to describe the orbital differentiation in strongly correlated electron systems starting from first principles. The approach enables us to treat strong electron correlations, spin-orbit coupling, and crystal field splittings on the same footing by exploiting the gauge invariance of the mean-field equations. We apply our theory to the archetypical nuclear fuel UO2 and show that the ground state of this system displays a pronounced orbital differentiation within the 5 f manifold, with Mott-localized Γ8 and extended Γ7 electrons.
Lattice simulation of a center symmetric three dimensional effective theory for SU(2) Yang-Mills
Energy Technology Data Exchange (ETDEWEB)
Smith, Dominik
2010-11-17
We present lattice simulations of a center symmetric dimensionally reduced effective field theory for SU(2) Yang Mills which employ thermal Wilson lines and three-dimensional magnetic fields as fundamental degrees of freedom. The action is composed of a gauge invariant kinetic term, spatial gauge fields and a potential for theWilson line which includes a ''fuzzy'' bag term to generate non-perturbative fluctuations between Z(2) degenerate ground states. The model is studied in the limit where the gauge fields are set to zero as well as the full model with gauge fields. We confirm that, at moderately weak coupling, the ''fuzzy'' bag term leads to eigenvalue repulsion in a finite region above the deconfining phase transition which shrinks in the extreme weak-coupling limit. A non-trivial Z(N) symmetric vacuum arises in the confined phase. The effective potential for the Polyakov loop in the theory with gauge fields is extracted from the simulations including all modes of the loop as well as for cooled configurations where the hard modes have been averaged out. The former is found to exhibit a non-analytic contribution while the latter can be described by a mean-field like ansatz with quadratic and quartic terms, plus a Vandermonde potential which depends upon the location within the phase diagram. Other results include the exact location of the phase boundary in the plane spanned by the coupling parameters, correlation lengths of several operators in the magnetic and electric sectors and the spatial string tension. We also present results from simulations of the full 4D Yang-Mills theory and attempt to make a qualitative comparison to the 3D effective theory. (orig.)
Free fermion resolution of supergroup WZNW models
Energy Technology Data Exchange (ETDEWEB)
Quella, T.; Schomerus, V.
2007-06-15
Extending our earlier work on PSL(2 vertical stroke 2), we explain how to reduce the solution of WZNW models on general type I supergroups to those defined on the bosonic subgroup. The new analysis covers in particular the supergroups GL(M vertical stroke N) along with several close relatives such as PSL(N vertical stroke N), certain Poincar'e supergroups and the series OSP(2 vertical stroke 2N). This remarkable progress relies on the use of a special Feigin-Fuchs type representation. In preparation for the field theory analysis, we shall exploit a minisuperspace analogue of a free fermion construction to deduce the spectrum of the Laplacian on type I supergroups. The latter is shown to be non-diagonalizable. After lifting these results to the full WZNW model, we address various issues of the field theory, including its modular invariance and the computation of correlation functions. In agreement with previous findings, supergroup WZNW models allow to study chiral and non-chiral aspects of logarithmic conformal field theory within a geometric framework. We shall briefly indicate how insights from WZNW models carry over to non-geometric examples, such as e.g. the W(p) triplet models.
The Baptism of Slaves, Freedmen and Free Muslims in the Oran of Philip II
Directory of Open Access Journals (Sweden)
Juan Jesús Bravo Caro
2016-04-01
Full Text Available The main objective of the article is to present new data on the volume of baptisms and conversions officiated in Oran during the last third of the sixteenth century. The parish documents preserved from this period are the basic source of analysis, supplemented by information emanating from different institutions that comprise the organizational management and administration of the Spain of XVI century. The categorization of Oran as a square border is going to confer specificity, also in the matter of slave presence, compared to other populations in the Spanish Monarchy in the Iberian Peninsula and island territories dependent on it. The percentage of enslaved people or freedmen entering the sacrament of baptism is higher than in many Spanish cities at the time, for the years studied. In addition, various members of Muslim families or Jewish religious contemplate this formula of conffesional income as a social integration via, or at least, a vehicle in realizing their existence in the Spanish society of the time, whether in Africa or the metropoli. As in other towns examined, the reference to the owners shows a participation of various groups in the slave market.
[Depression in former slave communities in Brazil: screening and associated factors].
Barroso, Sabrina Martins; Melo, Ana Paula Souto; Guimarães, Mark Drew Crosland
2014-04-01
To assess the prevalence and the factors associated with positive screening for major depressive episode (MDE) in former slave communities in the state of Bahia, Brazil. In this population-based, cross-sectional study, 764 participants were randomly selected from five former slave communities in Vitória da Conquista, Bahia, Brazil. Depression was defined as a cutoff score of 10 or more points and the presence of five or more symptoms according to the Patient Health Questionnaire (PHQ-9). Poisson regression was used to assess prevalence ratios (PR), with a 95% confidence interval (95%CI). Screening for MDE was positive in 12% of participants (95%CI: 10 - 14%), but only 2.3% reported a previous diagnosis. Depression was associated with self-reported poor or very poor health status (PR = 1.14; 95%CI: 1.04 - 1.26), chronic disease (PR = 1.08; 95%CI: 1.04 - 1.13), no physical activity (PR = 1.06; 95%CI: 1.01 - 1.11), and reasonable (PR = 1.07; 95%CI: 1.01 - 1.13) or poor access to health services (PR = 1.07; 95%CI: 1.02 - 1.12). The prevalence of MDE in this population was similar to that of the general Brazilian population. The association between MDE and poor access to health services indicates a missed opportunity for early diagnosis. Public measures against social and health inequalities are necessary to ensure equity in these communities.
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Luis G. Garcia-Valdovinos
2015-04-01
Full Text Available Transparency has been a major objective in bilateral teleoperation systems, even in the absence of time delay induced by the communication channel, since a high degree of transparency would allow humans to drive the remote teleoperator as if he or she were directly interacting with the remote environment, with the remote teleoperator as a physical and sensorial extension of the operator. When fast convergence of position and force tracking errors are ensured by the control system, then complete transparency is obtained, which would ideally guarantee humans to be tightly kinaesthetically coupled. In this paper a model-free Cartesian second order sliding mode (SOSM PD control scheme for nonlinear master-slave systems is presented. The proposed scheme does not rely on velocity measurements and attains very fast convergence of position trajectories, with bounded tracking of force trajectories, rendering a high degree of transparency with lesser knowledge of the system. The degree of transparency can easily be improved by tuning a feedback gain in the force loop. A unique energy storage function is introduced; such that a similar Cartesian-based controller is implemented in the master and slave sides. The resulting properties of the Cartesian control structure allows the human operator to input directly Cartesian variables, which makes clearer the kinaesthetic coupling, thus the proposed controller becomes a suitable candidate for practical implementation. The performance of the proposed scheme is evaluated in a semi-experimental setup.
The Term Mamlūk and Slave Status during the Mamluk Sultanate
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Yosef, Koby
2013-06-01
Full Text Available Scholars of the Mamluk Sultanate generally maintain that the status of all the mamlūk was that of an elite, and that the mamlūk were proud of their slave origin even after manumission. It is here argued that these assertions are based on a misconception of the term mamlūk as used in Mamluk sources. The term mamlūk has a double meaning: slave and servant, and it frequently expresses subordination, obedience and servitude. It is never used to express pride in slave status or slave origin. There is no evidence that manumitted mamlūk were proud of their slave status. On the contrary, manumitted slaves with aspirations made great efforts to repress their servile past by claiming an exalted origin or by creating marital ties with established families. Mamlūks were considered property and they lacked a legal identity of their own. They were often manumitted only upon their master’s death. They perceived themselves as slaves for lacking family ties. Only an outstanding few succeeded in completely freeing themselves of their slave status and become members of a ruling elite with family ties. It seems that starting from al-Nāṣir Muḥammad b. Qalāwūn’s third reign the enslavement of Turkish mamlūks who had been sold by their families became more of a formality. On the other hand, non-Turkish mamlūks, who were generally Christian war captives, were subject to discrimination. They were disdained, manumitted at a later age and prevented from establishing marital ties with the Qalawunids and creating their own families at a young age. They were perceived by their contemporaries as being “more slaves” than the Turkish mamlūks.Los estudiosos del sultanato mameluco generalmente sostienen que todos los mamlūk formaban parte de una élite que se sentía orgullosa de su origen esclavo incluso después de ser liberados. En este artículo se argumenta que esas afirmaciones están basadas en una interpretación errónea del término mamlūk seg
Instantons, vortices and confinement in SU(2) Yang-Mills theory
Energy Technology Data Exchange (ETDEWEB)
Lemos, A.L.L. de [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Oxman, L.E.; Teixeira, B.F.I. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil)
2012-07-01
Full text: In this work, we derive a recently proposed Abelian model to describe the interaction of correlated instantons, center vortices, and dual fields in three dimensional SU(2) Yang-Mills theory. Correlated monopoles and center vortices are believed to play a relevant role in accommodating the different properties of the confining string in Yang-Mills theories, receiving support from lattice simulations. In fact, scenarios based on either monopoles or closed center vortices are only partially successful to describe the expected behavior of the potential between quarks. At asymptotic distances, this potential should be linear and depend on the representation of the subgroup Z(N) of SU(N) (N-ality). At intermediate scales, it should posses Casimir scaling. The Cho-Faddeev- Niemi representation (CFN) can be used to associate monopoles with defects of the local color frame used to decompose the gauge fields. This possible frame defects can be extended to describe not only monopoles but also center vortices, correlated or not. In these scenarios, one of the difficulties is how to deal with the integration over an ensemble of extended objects, after considering a phenomenological parametrization of their properties, such as stiffness, interactions with dual fields, and interactions between them. This is particularly severe in four dimensional theories where center vortices generate two dimensional extended world surfaces. However, in three dimensions center vortices are stringlike and an ensemble of world lines is naturally associated with a second quantized field theory. The aim of this work is presenting a careful derivation of an effective model, considering instantons and center vortices in D=3 SU(3) theory, after parameterizing some intrinsic physical properties that these objects could present. One of the fundamental ingredients will be the adoption of recent techniques borrowed from polymer physics, where the extended objects are also one dimensional. This
Ruiz, Eduardo
2014-01-01
Cervantes's "novela" creates a complex protagonist due in part to the involvement of the slaves' destructive and creative energies: a linguistic and erotic paradox. Linguistically the female slave foregrounds the historical dichotomy between "ladinos" and "bozales" and the related problematic of conversion,…
Coupled fermion-kink system in Jackiw-Rebbi model
Energy Technology Data Exchange (ETDEWEB)
Amado, A.; Mohammadi, A. [Universidade Federal de Pernambuco, Departamento de Fisica, Recife, PE (Brazil)
2017-07-15
In this paper, we study Jackiw-Rebbi model, in which a massless fermion is coupled to the kink of λφ{sup 4} theory through a Yukawa interaction. In the original Jackiw-Rebbi model, the soliton is prescribed. However, we are interested in the back-reaction of the fermion on the soliton besides the effect of the soliton on the fermion. Also, as a particular example, we consider a minimal supersymmetric kink model in (1 + 1) dimensions. In this case, the bosonic self-coupling, λ, and the Yukawa coupling between fermion and soliton, g, have a specific relation, g = √(λ/2). As the set of coupled equations of motion of the system is not analytically solvable, we use a numerical method to solve it self-consistently. We obtain the bound energy spectrum, bound states of the system and the corresponding shape of the soliton using a relaxation method, except for the zero mode fermionic state and threshold energies which are analytically solvable. With the aid of these results, we are able to show how the soliton is affected in general and supersymmetric cases. The results we obtain are consistent with the ones in the literature, considering the soliton as background. (orig.)
Spectral triples and associated Connes-de Rham complex for the quantum SU(2) and the quantum sphere
Chakraborty, Partha Sarathi; Pal, Arupkumar
2002-01-01
We construct spectral triples for the C^*-algebra of continuous functions on the quantum SU(2) group and the quantum sphere. There has been various approaches towards building a calculus on quantum spaces, but there seems to be very few instances of computations outlined in chapter~6 of Connes' book. We give detailed computations of the associated Connes-de Rham complex and the space of L_2-forms.
Energy Technology Data Exchange (ETDEWEB)
Shnirman, A., E-mail: alexander.shnirman@kit.edu [Karlsruhe Institute of Technology, Institut fur Theorie der Kondensierten Materie (Germany); Saha, A. [Institute of Physics (India); Burmistrov, I. S. [Russian Academy of Sciences, Landau Institute for Theoretical Physics (Russian Federation); Kiselev, M. N. [International Center for Theoretical Physics (Italy); Altland, A. [Universität zu Köln, Institut für Theoretische Physik (Germany); Gefen, Y. [Weizmann Institute of Science, Department of Condensed Matter Physics (Israel)
2016-03-15
There are two paradigmatic frameworks for treating quantum systems coupled to a dissipative environment: the Caldeira–Leggett and Ambegaokar–Eckern–Schön approaches. Here, we recall the differences between them and explain the consequences of applying each to a zero-dimensional spin (having an SU(2) symmetry) in a dissipative environment (a dissipative quantum dot near or beyond the Stoner instability point).
Directory of Open Access Journals (Sweden)
Aram A. Shahin
2015-06-01
Full Text Available Abstract: Slave-girls, and in particular singing slave-girls, hold a prominent place in Islamic literary sources. These sources provide quite a number of stories in which the masters of slave-girls fall deeply in love with them, and then, when faced with the prospect of separation or are indeed separated from them, humble themselves and risk losing their honour, all of their wealth, and even their own lives in order to be reunited with the girl whom they love. In some stories, intelligent and learned slave-girls take the initiative to preserve their relationships with their masters who are often depicted as inept and clueless. In the end, the girl is typically given her freedom and marries her master. Although the men are the legal masters of the slave-girls, it seems that there is an inversion of the master/slave roles in the tales and that it is the slave-girl who controls the destiny of both.Resumen: Las esclavas, con mención especial de las que cantan, tienen un lugar de preferencia en las fuentes literarias islamistas. Estas fuentes proveen un gran número de cuentos en los que los amos de estas esclavas se enamoran de ellas y luego al afrontarse la posibilidad de separación, y de hecho los dos se encuentran separados, se humillan y corren el riesgo de perder su honor, toda su riqueza y hasta sus propias vidas para reunirse con la chica que aman. En algunos cuentos, esclavas listas y doctas toman la iniciativa para preservar sus relaciones con los dueños, quienes parecen ser torpes y negados. A fin de cuentas, la chica suele recibir su libertad y se casa con el amo. A pesar de ser el amo legal de las esclavas, parece que hay una inversión de los papeles de amo/esclavo en estos cuentos y es la esclava la que controla el destino de los dos.
Implementation of the SU(2) Hamiltonian symmetry for the DMRG algorithm
Alvarez, Gonzalo
2012-10-01
In the Density Matrix Renormalization Group (DMRG) algorithm (White, 1992, 1993) [1,2], Hamiltonian symmetries play an important rôle. Using symmetries, the matrix representation of the Hamiltonian can be blocked. Diagonalizing each matrix block is more efficient than diagonalizing the original matrix. This paper explains how the the DMRG++ code (Alvarez, 2009) [3] has been extended to handle the non-local SU(2) symmetry in a model independent way. Improvements in CPU times compared to runs with only local symmetries are discussed for the one-orbital Hubbard model, and for a two-orbital Hubbard model for iron-based superconductors. The computational bottleneck of the algorithm and the use of shared memory parallelization are also addressed. Program summary Program title: DMRG++ Catalog identifier: AEDJ_v2_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEDJ_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Special license. See http://cpc.cs.qub.ac.uk/licence/AEDJ_v2_0.html No. of lines in distributed program, including test data, etc.: 211560 No. of bytes in distributed program, including test data, etc.: 10572185 Distribution format: tar.gz Programming language: C++. Computer: PC. Operating system: Multiplatform, tested on Linux. Has the code been vectorized or parallelized?: Yes. 1 to 8 processors with MPI, 2 to 4 cores with pthreads. RAM: 1GB (256MB is enough to run the included test) Classification: 23. Catalog identifier of previous version: AEDJ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 180(2009)1572 External routines: BLAS and LAPACK Nature of problem: Strongly correlated electrons systems, display a broad range of important phenomena, and their study is a major area of research in condensed matter physics. In this context, model Hamiltonians are used to simulate the relevant interactions of a given compound, and the relevant degrees of freedom. These studies
Four-fermion simulation at LEP2 in DELPHI
Ballestrero, A; Cossutti, F; Migliore, E
2003-01-01
We present and discuss the generator setup for $e^+e^-\\rightarrow 4f$ processes chosen by the DELPHI collaboration. The need to combine the most recent theoretical achievements in the CC03 sector with the state of the art description of the remaining part of the 4-fermion processes has led to an original combination of different codes, with the {\\tt WPHACT 2.0} 4-fermion generator and the {\\tt YFSWW} code for the CC03 $\\mathcal{O}(\\alpha)$ corrections as a starting point. The coverage of the 4-fermion phase space is discussed in detail, with particular attention to ensuring the compatibility of {\\tt WPHACT} with dedicated $\\gamma\\gamma$ generators.
Fermionic corrections to fluid dynamics from BTZ black hole
Energy Technology Data Exchange (ETDEWEB)
Gentile, L.G.C. [DISIT, Università del Piemonte Orientale,via T. Michel, 11, Alessandria, 15120 (Italy); Dipartimento di Fisica “Galileo Galilei”,Università di Padova, via Marzolo 8, 35131 Padova (Italy); INFN - Sezione di Padova,via Marzolo 8, 35131, Padova (Italy); Grassi, P.A. [DISIT, Università del Piemonte Orientale,via T. Michel, 11, Alessandria, 15120 (Italy); INFN - Gruppo Collegato di Alessandria, Sezione di Torino,Alessandria (Italy); PH-TH Department, CERN,CH-1211 Geneva 23 (Switzerland); Mezzalira, A. [Dipartimento di Fisica Teorica, Università di Torino,via P. Giuria, 1, Torino, 10125 (Italy); INFN - Gruppo Collegato di Alessandria, Sezione di Torino,Alessandria (Italy)
2015-11-23
We reconstruct the complete fermionic orbit of the non-extremal BTZ black hole by acting with finite supersymmetry transformations. The solution satisfies the exact supergravity equations of motion to all orders in the fermonic expansion and the final result is given in terms of fermionic bilinears. By fluid/gravity correspondence, we derive linearized Navier-Stokes equations and a set of new differential equations from Rarita-Schwinger equation. We compute the boundary energy-momentum tensor and we interpret the result as a perfect fluid with a modified definition of fluid velocity. Finally, we derive the modified expression for the entropy of the black hole in terms of the fermionic bilinears.
A local factorization of the fermion determinant in lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Ce, Marco [Scuola Normale Superiore, Pisa (Italy); INFN, Pisa (Italy); Giusti, Leonardo [Milano-Bicocca Univ. (Italy). Dipartimento di Fisica; INFN, Milano-Bicocca (Italy); Schaefer, Stefan [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2016-09-15
We introduce a factorization of the fermion determinant in lattice QCD with Wilson-type fermions that leads to a bosonic action which is local in the block fields. The interaction among gauge fields on distant blocks is mediated by multiboson fields located on the boundaries of the blocks. The resultant multiboson domain-decomposed hybrid Monte Carlo passes extensive numerical tests carried out by measuring standard gluonic observables. The combination of the determinant factorization and of the one of the propagator, that we put forward recently, paves the way for multilevel Monte Carlo integration in the presence of fermions. We test this possibility by computing the disconnected correlator of two flavor-diagonal pseudoscalar densities, and we observe a significant increase of the signal-to-noise ratio due to a two-level integration.
Fermionic projected entangled-pair states and topological phases
Bultinck, Nick; Williamson, Dominic J.; Haegeman, Jutho; Verstraete, Frank
2018-01-01
We study fermionic matrix product operator algebras and identify the associated algebraic data. Using this algebraic data we construct fermionic tensor network states in two dimensions that have non-trivial symmetry-protected or intrinsic topological order. The tensor network states allow us to relate physical properties of the topological phases to the underlying algebraic data. We illustrate this by calculating defect properties and modular matrices of supercohomology phases. Our formalism also captures Majorana defects as we show explicitly for a class of {Z}2 symmetry-protected and intrinsic topological phases. The tensor networks states presented here are well-suited for numerical applications and hence open up new possibilities for studying interacting fermionic topological phases.
SO(10) models for flavor with vector-like fermions
Saad, Shaikh
2017-11-01
In this work, unified models based on S O(10) symmetry is presented which provides insights into the flavor observables of charged fermions and the neutrinos. Unlike the conventional S O(10) models, the Higgs boson 10H belonging to the fundamental representation is not present in this new class of models. Instead vector-like fermions in the 16 + 16 ¯ representation is introduced to induce the flavor mixing. A variety of scenarios, both non-supersymmetric and supersymmetric, are studied involving a 126 ¯H Higgs boson. For symmetry breaking purpose, 126 ¯H Higgs is accompanied by either a 45H or a 210H of Higgs boson. Our analysis shows that this framework, by utilizing either type-I or type-II seesaw mechanism, an excellent fit to the fermion masses and mixings can be obtained with a limited number of parameters. To test and distinguish these flavor models, proton decay branching ratios are also computed.
Strongly-correlated fermionic matter in the dilute limit
Energy Technology Data Exchange (ETDEWEB)
Mihaila, Bogdan [Los Alamos National Laboratory; Cardenas, Andres L [Los Alamos National Laboratory
2008-01-01
We study 'the ground-state properties of the many-body system composed of spin-l/2 fermions interacting via a zero-range, infinite scattering length contact interaction.' Sometimes referred to as the George Bertsch problem, it is of particular interest in astrophysics in connection with the equation of state for neutron matter and has been revisited recently with the advent of experimental studies of the BCS to BEC crossover in ultracold fermionic atom gases. We will show that new insights into the solution to this problem are obtained in the context of a coupled-cluster (exp S) expansion approach to calculating the equation of state for dilute fermionic systems and that present state-of-the-art Monte Carlo calculations have not yet provided the definitive answer.
Water and Metasomatism in the Slave Cratonic Lithosphere (Canada): An FTIR Study
Kilgore, McKensie; Peslier, Anne H.; Brandon, Alan D.; Schaffer, Lillian Aurora; Pearson, D. Graham; O'Reilly, Suzanne Yvette; Kopylova, Maya G.; Griffin, William L.
2017-01-01
Water in the mantle influences melting, viscosity, seismic velocity, and electrical conductivity. The role played by water in the long-term stabilization of cratonic roots is currently being debated. This study focuses on water contents of mantle minerals (olivine, pyroxene and garnet) from xenoliths found in kimberlites of the Archean Slave craton. 19 mantle xenoliths from central Lac de Gras, and 10 from northern Jericho were analyzed by FTIR for water, and their equilibration depths span the several compositional layers identified beneath the region. At both locations, the shallow peridotites have lower water contents in their olivines (11-30 ppm H2O) than those from the deeper layers (28-300 ppm H2O). The driest olivines, however, are not at the base of the cratonic lithosphere (>6 GPa) as in the Kaapvaal craton. Instead, the deepest olivines are hydrous (31-72 ppm H2O at Lac de Gras and 275 ppm H2O at Jericho). Correlations of water in clinopyroxene and garnet with their other trace element contents are consistent with water being added by metasomatism by melts resembling kimberlite precursors in the mantle approx.0.35 Ga ago beneath Lac de Gras. The northern Jericho xenoliths are derived from a region of the Slave craton that is even more chemically stratified, and was affected at depth by the 1.27 Ga Mackenzie igneous events. Metasomatism at Jericho may be responsible for the particularly high olivine water contents (up to 300 ppm H2O) compared to those at Lac de Gras, which will be investigated by acquiring trace-element data on these xenoliths. These data indicate that several episodes of metasomatic rehydration occurred in the deep part of the Slave craton mantle lithosphere, with the process being more intense in the northern part beneath Jericho, likely related to a translithospheric suture serving as a channel to introduce fluids and/or melts in the northern region. Consequently, rehydration of the lithosphere does not necessarily cause cratonic root
Bakker, N.H.; Passenier, P.O.; Werkhoven, P.J.
2003-01-01
The type of navigation interface in a virtual environment (VE) - head slaved or indirect - determines whether or not proprioceptive feedback stimuli are present during movement. In addition, teleports can be used, which do not provide continuous movement but, rather, discontinuously displace the
Travelling hierarchies : moving in and out of slave status in a Central Malian FulBe network
Pelckmans, Lotte
2011-01-01
Based on rich and wide-ranging data, this thesis describes the sensitive issue of the contemporary emancipation trajectories of agro-pastoralist Fulɓe in Central Mali. It explores how people are currently dealing with hierarchies they inherited from past master-slave relations and focuses on the
Wijnhoven, Alphonsus B.J.M.
2012-01-01
This article discusses people's understanding of reality by representations from the Internet. The Hegelian inquiry system is used here to explain the nature of informing on the Internet as activities of information masters to influence information slaves' opinions and as activities of information
Direct Measurement of the Higgs Boson Fermionic Couplings at CMS
CERN. Geneva
2013-01-01
The couplings between the Higgs and fermionic fields can be accessed directly through processes in which the Higgs boson decays into fermions, or is produced in association with a top-quark pair. Several analyses based on the full dataset collected by CMS at 7 and 8 TeV are presented. In particular, the final results of searches for a Higgs boson decaying into a b-quark or a tau-lepton pair are presented, together with a preliminary combination of these results.
Four-Fermion Limit of Gauge-Yukawa Theories
DEFF Research Database (Denmark)
Krog, Jens; Mojaza, Matin; Sannino, Francesco
2015-01-01
perturbative gauge-Yukawa theories can have a strongly coupled limit at high-energy, that can be mapped into a four-fermion theory. Interestingly, we are able to precisely carve out a region of the perturbative parameter space supporting such a composite limit. This has interesting implications on our current...... degree of freedom at the ultraviolet composite scale, where it gives away to the four-fermion interactions. We compute the hierarchy between the ultraviolet and infrared composite scales of the theory and show that they are naturally large and well separated. Our results show that some weakly coupled...
Duality of boson and fermion: New intermediate-statistics
Chung, Won Sang; Algin, Abdullah
2017-10-01
In this work, we propose a new model for describing an intermediate-statistics particles system. Starting with a deformed grand partition function, we investigate several thermodynamical and statistical properties of a gas model of two-parameter deformed particles. We specifically focus on the low-temperature behavior of the model and the conditions under which either boson condensation or fermion condensation would occur in such a model are discussed. Our results obtained in this study reveal that the present deformed gas model exhibits duality of boson and fermion, and can be useful for approaching the thermostatistics of condensation characteristics in quantum systems.
CePtSi: A new heavy-fermion compound
Energy Technology Data Exchange (ETDEWEB)
Lee, W.H.; Shelton, R.N.
1987-04-01
We find that CePtSi is a new heavy-fermion and coherent dense Kondo-lattice compound with no magnetic or superconducting transition above 70 mK. Measurements of the magnetic contribution to the electrical resistivity, static magnetic susceptibility, and low-temperature heat capacity of CePtSi are reported. This compound has a large value of the low-temperature magnetic susceptibility (chi(2.4 K) = 24.9 x 10/sup -3/ cm/sup 3//mol) and, characteristic of heavy-fermion compounds, an enormous coefficient of the electronic specific heat, ..gamma..approx.800 mJ/molX sup 2: .
No fermionic wigs for BPS attractors in 5 dimensions
Energy Technology Data Exchange (ETDEWEB)
Gentile, Lorenzo G.C., E-mail: lgentile@pd.infn.it [DISIT, Università del Piemonte Orientale, via T. Michel, 11, Alessandria I-15120 (Italy); Dipartimento di Fisica “Galileo Galilei”, Università di Padova, via Marzolo 8, I-35131 Padova (Italy); INFN, Sezione di Padova, via Marzolo 8, I-35131 Padova (Italy); Grassi, Pietro A., E-mail: pgrassi@mfn.unipmn.it [DISIT, Università del Piemonte Orientale, via T. Michel, 11, Alessandria I-15120 (Italy); INFN – Gruppo Collegato di Alessandria – Sezione di Torino (Italy); Marrani, Alessio, E-mail: alessio.marrani@fys.kuleuven.be [Instituut voor Theoretische Fysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Mezzalira, Andrea, E-mail: andrea.mezzalira@ulb.ac.be [Physique Théorique et Mathématique, Université Libre de Bruxelles, C.P. 231, B-1050 Bruxelles (Belgium); Sabra, Wafic A., E-mail: ws00@aub.edu.lb [Centre for Advanced Mathematical Sciences and Physics Department, American University of Beirut (Lebanon)
2014-07-30
We analyze the fermionic wigging of 1/2-BPS (electric) extremal black hole attractors in N=2, D=5 ungauged Maxwell–Einstein supergravity theories, by exploiting anti-Killing spinors supersymmetry transformations. Regardless of the specific data of the real special geometry of the manifold defining the scalars of the vector multiplets, and differently from the D=4 case, we find that there are no corrections for the near-horizon attractor value of the scalar fields; an analogous result also holds for 1/2-BPS (magnetic) extremal black string. Thus, the attractor mechanism receives no fermionic corrections in D=5 (at least in the BPS sector)
Component separation in harmonically trapped boson-fermion mixtures
DEFF Research Database (Denmark)
Nygaard, Nicolai; Mølmer, Klaus
1999-01-01
We present a numerical study of mixed boson-fermion systems at zero temperature in isotropic and anise tropic harmonic traps. We investigate the phenomenon of component separation as a function of the strength ut the interparticle interaction. While solving a Gross-Pitaevskii mean-field equation ...... for the boson distribution in the trap, we utilize two different methods to extract the density profile of the fermion component; a semiclassical Thomas-Fermi approximation and a quantum-mechanical Slater determinant Schrodinger equation....
Disorder operators in Chern-Simons-fermion theories
Energy Technology Data Exchange (ETDEWEB)
Radičević, Ðorđe [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States)
2016-03-18
Building on the recent progress in solving Chern-Simons-matter theories in the planar limit, we compute the scaling dimensions of a large class of disorder (“monopole”) operators in U(N){sub k} Chern-Simons-fermion theories at all ’t Hooft couplings. We find that the lowest-dimension operator of this sort has dimension (2/3)k{sup 3/2}. We comment on the implications of these results to analyzing maps of fermionic disorder operators under 3D bosonization.
Ultracold Fermions in a Cavity-Induced Artificial Magnetic Field
Kollath, Corinna; Sheikhan, Ameneh; Wolff, Stefan; Brennecke, Ferdinand
2016-02-01
We propose how a fermionic quantum gas confined to an optical lattice and coupled to an optical cavity can self-organize into a state where the spontaneously emerging cavity field amplitude induces an artificial magnetic field. The fermions form either a chiral insulator or a chiral liquid carrying chiral currents. The feedback mechanism via the dynamical cavity field enables robust and fast switching in time of the chiral phases, and the cavity output can be employed for a direct nondestructive measurement of the chiral current.
Trapped fermions in a synthetic non-Abelian gauge field
Ghosh, Sudeep Kumar; Vyasanakere, Jayantha P.; Shenoy, Vijay B.
2011-01-01
On increasing the coupling strength ($\\lambda$) of a non-Abelian gauge field that induces a generalized Rashba spin-orbit interaction, the topology of the Fermi surface of a homogeneous gas of noninteracting fermions of density $\\rho \\sim \\kf^3$ undergoes a change at a critical value, $\\lambda_T \\approx \\kf$ [Phys. Rev. B {\\bf 84}, 014512 (2011)]. In this paper we analyze how this phenomenon affects the size and shape of a cloud of spin-$\\half$ fermions trapped in a harmonic potential such as...
Fermi wave vector for the partially spin-polarized composite-fermion Fermi sea
DEFF Research Database (Denmark)
Coimbatore Balram, Ajit; Jain, Jainendra
2017-01-01
The fully spin polarized composite fermion (CF) Fermi sea at half filled lowest Landau level has a Fermi wave vector $k^*_{\\rm F}=\\sqrt{4\\pi\\rho_e}$, where $\\rho_e$ is the density of electrons or composite fermions, supporting the notion that the interaction between composite fermions can...... CFFSs at $\
(2+1)-Dimensional QED with dynamically massive fermions in vacuum polarization
Gusynin, VP; Hams, AH; Reenders, M
1996-01-01
We study chiral symmetry breaking in three-dimensional QED with N-f flavors of four-component fermions. A closed system of Schwinger-Dyson equations for fermion and photon propagators and the full fermion-photon vertex is proposed, which is consistent with the Ward-Takahashi identity. A simplified
Brazilian Ex-Slaves' Return to Africa: Xvii-Xix Historiography
Directory of Open Access Journals (Sweden)
Ilana Peliciari Rocha
2013-12-01
Full Text Available The article is about Brazilian communities of ex-slaves who returned to Africa and proposes a change of the historiographic perspective, which considers the interrelationship between the history of both continents. The Africans who returned from Brazil, in the 17th and 19th centuries, took with them the experience in Brazil and influenced their new African communities. Based on this theme, this paper presents the main discussions of historiography, pointing out aspects such as: culture, religion, family, the political and economic integration, the issue of ethnicity and identity. It presents a review of classic and current studies on the theme and its reflections and demonstrates the contribution of historiography to the advancement of the knowledge of the African diaspora. The analysis is bibliographical and considers the period of African slavery in Brazil.
Rethinking sin and evil through the life of a child sex slave
Directory of Open Access Journals (Sweden)
Chris Jones
2016-02-01
Full Text Available This article rethinks (original sin and evil through the life of a child called Engela who has been ‘sold’ into sex slavery. Focus is placed on the high value with which children should be regarded, especially children who have been sold as sex slaves. During this argument the emphasis is placed on ecclesiastical evolutionary perspectives on creation as well as relevantand contemporary understandings of sin and evil, and related to this, the devil and hell. Towards the end of the article theological consideration is given to fatherlessness, because Engela’s father was often absent in her life. According to literature, Jesus in all probability grew up without a father too. It seems as if Joseph played a minimal role in his life and education, whilst Jesus’ own experience of rejection laid the foundation for his compassion with the socially rejected, particularly children. Fatherlessness from a black African liberation perspective is also contextualised and applied.
A Critical Analysis of the Philosophical-Political Element of the Master-Slave Dialectic
Directory of Open Access Journals (Sweden)
Matheus Pelegrino da Silva
2015-12-01
Full Text Available ABSTRACT:The section “Lordship and Bondage” in Hegel’s Phenomenology of Spirit offers us, through the criticism of slavery, some indications regarding Hegel’s conception of human nature. In this paper some consequences of this conception for Hegel’s political philosophy are identified and presented. The analysis shows problems may emerge when we analyze some fundamental Hegelian concepts – “recognition” and shows that some “men” – if we take into consideration the way these concepts were defined in the master-slave dialectic. In light of these problems it is pointed out that Hegel’s political philosophy, and also his position regarding slavery, become less cogent and more susceptible to criticism. The last part of the text analyzes some consequences of problems related to the possibility of defining the concepts “recognition” and “men” in terms of Hegel’s model of state.
A Master-Slave Surveillance System to Acquire Panoramic and Multiscale Videos
Directory of Open Access Journals (Sweden)
Yu Liu
2014-01-01
Full Text Available This paper describes a master-slave visual surveillance system that uses stationary-dynamic camera assemblies to achieve wide field of view and selective focus of interest. In this system, the fish-eye panoramic camera is capable of monitoring a large area, and the PTZ dome camera has high mobility and zoom ability. In order to achieve the precise interaction, preprocessing spatial calibration between these two cameras is required. This paper introduces a novel calibration approach to automatically calculate a transformation matrix model between two coordinate systems by matching feature points. In addition, a distortion correction method based on Midpoint Circle Algorithm is proposed to handle obvious horizontal distortion in the captured panoramic image. Experimental results using realistic scenes have demonstrated the efficiency and applicability of the system with real-time surveillance.
Demography and pathology of an urban slave population from New Orleans.
Owsley, D W; Orser, C E; Mann, R W; Moore-Jansen, P H; Montgomery, R L
1987-10-01
Twenty-nine skeletons from the first cemetery in New Orleans provide significant new information about urban slavery in America. Dating as early as 1720 and used perhaps as late as 1810, the cemetery provided an identifiable sample of two whites, 13 blacks, one individual of possible Indian-white ancestry, and two possibly mulatto individuals. Numerous skeletal and dental lesions were noted in the series, and historical information was used in conjunction with the physical data to draw conclusions about rates and patterns of mortality. Pathological changes indicate that the cemetery contained individuals representing two slave occupational groups, house servants and laborers. This research provides information in the expanding area of Afro-American biohistorical research.
Pujari, Sumiran; Lang, Thomas C.; Kaul, Ribhu K.
Bernal-stacked bilayer graphene hosts an interesting 'non-relativistic' semi-metallic dispersion different from monolayer graphene. At this quadratic band touching, short-range interactions are marginal and hence cause instabilities to a variety of ground states. In this work we consider the instabilities of even N species of fermions on the Bernal bilayer with an SU (N) -symmetric contact interaction. For SU (2) fermions with an on-site Hubbard interaction the ground state has been found to be to a magnetic Néel state for all strengths of the interaction. In contrast, the leading weak coupling instability for N > 2 is a non-magnetic ground state, which is gapped and odd under time reversal. On the other hand, at strong coupling we expect Néel or VBS ground states of the effective self-conjugate SU (N) spin models. Motivated by this observation, we investigate the phase diagram for even N > 2 using determinantal quantum Monte Carlo computations. Support from NSF Grant DMR-1056536 and XSEDE Grant DMR-150037.
Interlayer superfluidity in bilayer systems of fermionic polar molecules
Pikovski, A.; Klawunn, M.; Shlyapnikov, G.V.; Santos, L.
2010-01-01
We consider fermionic polar molecules in a bilayer geometry where they are oriented perpendicularly to the layers, which permits both low inelastic losses and superfluid pairing. The dipole-dipole interaction between molecules of different layers leads to the emergence of interlayer superfluids. The
Higgs interchange and bound states of superheavy fermions
Indian Academy of Sciences (India)
Hypothetical superheavy fourth-generation fermions with a very small coupling with the rest of the Standard Model can give rise to long enough lived bound states. The production and the detection of these bound states would be experimentally feasible at the LHC. Extending, in the present study, the analysis of other ...
Stable topological superfluid phase of ultracold polar fermionic molecules
Cooper, N.R.; Shlyapnikov, G.V.
2009-01-01
We show that single-component fermionic polar molecules confined to a 2D geometry and dressed by a microwave field may acquire an attractive 1/r(3) dipole-dipole interaction leading to superfluid p-wave pairing at sufficiently low temperatures even in the BCS regime. The emerging state is the
Topological px+ipy superfluid phase of fermionic polar molecules
Levinsen, J.; Cooper, N.R.; Shlyapnikov, G.V.
2011-01-01
We discuss the topological px+ipy superfluid phase in a 2D gas of single-component fermionic polar molecules dressed by a circularly polarized microwave field. This phase emerges because the molecules may interact with each other via a potential Vo(r) that has an attractive dipole-dipole 1/r^3 tail,
Novel p-wave superfluids of fermionic polar molecules
Fedorov, A.K.; Matveenko, S.I.; Yudson, V.I.; Shlyapnikov, G.V.
2016-01-01
Recently suggested subwavelength lattices offer remarkable prospects for the observation of novel superfluids of fermionic polar molecules. It becomes realistic to obtain a topological p-wave superfluid of microwave-dressed polar molecules in 2D lattices at temperatures of the order of tens of
Moduli and Kähler potential in fermionic strings
López, J L; Yuan, K; Lopez, Jorge L.; Yuan, Kajia
1994-01-01
We study the problem of identifying the moduli fields in fermionic four-dimensional string models. We deform a free-fermionic model by introducing exactly marginal operators in the form of Abelian Thirring interactions on the world-sheet, and show that their couplings correspond to the untwisted moduli fields. We study the consequences of this method for simple free-fermionic models which correspond to $Z_2\\times Z_2$ orbifolds and obtain their moduli space and K\\"ahler potential by symmetry arguments and by direct calculation of string scattering amplitudes. We then generalize our analysis to more complicated fermionic structures which arise in constructions of realistic models corresponding to asymmetric orbifolds, and obtain the moduli space and K\\"ahler potential for this case. Finally we extend our analysis to the untwisted matter sector and derive expressions for the full K\\"ahler potential to be used in phenomenological applications, and the target space duality transformations of the corresponding unt...
Heavy-fermion superconductivity | Ekpekpo | Nigerian Journal of ...
African Journals Online (AJOL)
... whose f-shell electrons are strongly correlated. The theories presented in this paper were developed mainly to describe effects in heavy fermion superconductors. Nevertheless, the general aspects of these theories may also be applicable to the class of CUD or organic superconductors. Nigerian Journal of Physics Vol.
Boson-fermion duality and metastability in cuprate superconductors
Ranninger, J.; Domański, T.
2010-01-01
The intrinsic structural metastability in cuprate high- Tc materials, evidenced in a checkerboard domain structure of the CuO2 planes, locally breaks translational and rotational symmetry. Dynamical charge-deformation fluctuations of such nanosize unidirectional domains, involving Cu-O-Cu molecular bonds, result in resonantly fluctuating diamagnetic pairs embedded in a correlated Fermi liquid. As a consequence, the single-particle spectral properties acquire simultaneously (i) fermionic low-energy Bogoliubov branches for propagating Cooper pairs and (ii) bosonic localized glassy structures for tightly bound states of them at high energies. The partial localization of the single-particle excitations leads to a fractionation of the Fermi surface as the strength of the exchange coupling between itinerant fermions and partially localized fermion pairs increases upon moving from the nodal to the antinodal point. This is also the reason why bound fermion pairs accumulate near the antinodal points and thereby control the doping dependence of the cuprates upon approaching the singular universal optimal doping rate.
Standard electromagnetically driven cosmology coupled with fermionic source
Energy Technology Data Exchange (ETDEWEB)
Mello, M. M. C., E-mail: mmcmello@gmail.com [Universidade Federal do ABC - UFABC Santo André (Brazil); Klippert, R., E-mail: klippert@unifei.edu.br [Instituto de Matemática e Computação, Universidade Federal de Itajubá Av. BPS 1303 Pinheirinho, 37500-903, Itajubá (Brazil)
2015-03-10
Dirac fermions and electromagnetic fields are considered as the source of gravitation in the framework of standard Friedmann-Lemaître-Robertson-Walker (FLRW) cosmology. It is shown that all solutions for the scale-factor a(t) are non-singular, provided the cosmological constant Λ is set to be less than the positive inverse of a quantum scale.
Photoelectron spectroscopy in heavy fermions: Inconsistencies with the Kondo model
Energy Technology Data Exchange (ETDEWEB)
Arko, A.J.; Joyce, J.J.; Blyth, R.R.; Canfield, P.C.; Thompson, J.D.; Bartlett, R.J.; Fisk, Z. [Los Alamos National Lab., NM (United States); Lawrence, J.; Tang, J. [California Univ., Irvine, CA (United States); Riseborough, P. [Polytechnic Univ., Brooklyn, NY (United States)
1992-09-01
We have investigated a number of Ce and Yb heavy fermion compounds via photoelectron spectroscopy and compared the results to the predictions of the Imurity Anderson Hamiltonian within the Gunnarson-Schonhammer approach. For the low T{sub K} materials investigated we find little or no correlation with T{sub K}, the only parameter that can be determined independent of photoemission.
Fermion superfluid with hybridized s- and p-wave pairings
Zhou, LiHong; Yi, Wei; Cui, XiaoLing
2017-12-01
Ever since the pioneering work of Bardeen, Cooper and Schrieffer in the 1950s, exploring novel pairing mechanisms for fermion superfluids has become one of the central tasks in modern physics. Here, we investigate a new type of fermion superfluid with hybridized s- and p-wave pairings in an ultracold spin-1/2 Fermi gas. Its occurrence is facilitated by the co-existence of comparable s- and p-wave interactions, which is realizable in a two-component 40K Fermi gas with close-by s- and p-wave Feshbach resonances. The hybridized superfluid state is stable over a considerable parameter region on the phase diagram, and can lead to intriguing patterns of spin densities and pairing fields in momentum space. In particular, it can induce a phase-locked p-wave pairing in the fermion species that has no p-wave interactions. The hybridized nature of this novel superfluid can also be confirmed by measuring the s- and p-wave contacts, which can be extracted from the high-momentum tail of the momentum distribution of each spin component. These results enrich our knowledge of pairing superfluidity in Fermi systems, and open the avenue for achieving novel fermion superfluids with multiple partial-wave scatterings in cold atomic gases.
Emergent Majorana Fermions and their Restricted Clifford Algebra
Jackiw, R.
2014-01-01
Dedicated to Ludwig Faddeev on his 80th birthday. Ludwig exemplifies perfectly a mathematical physicist: significant contribution to mathematics (algebraic properties of integrable systems) and physics (quantum field theory). In this note I present an exercise which bridges mathematics (restricted Clifford algebra) to physics (Majorana fermions).
A fermion-boson composite model of quarks and leptons
Directory of Open Access Journals (Sweden)
Yoshio Koide
1983-01-01
Full Text Available Quark and lepton masses and flavor-mixing angles are estimated on the basis of a fermion-boson composite model where the (u, d, (c, s and (t, b quarks are assigned to the diagonal elements π8, η8 and η1, respectively, in3 × 3* = 8 + 1 of the SU(3-generation symmetry.
Measurements of four fermion cross-sections at LEP
Kopal, Miroslav
2002-01-01
The production of four fermions in e+e− collisions at LEP allows the verification of the Standard Model of the Electroweak Interactions in the Charged and Neutral Current Sectors. Among the four-fermion final states, the highest purity and the clearest four-fermion events are characterized by the presence of leptons in the final state. The identification of such final states in the full data sample collected by the L3 experiment at LEP in the years from 1997 through 2000 is described. The total amount of data analyzed in this thesis corresponds to the total integrated luminosity 675.5 pb−1. ^ This thesis presents the results of the selection of the Z boson pair production together with the measurement of the cross-section for leptonic four-fermion final states, and the first measurement of cross-sections in the four-lepton and two-lepton and missing energy channels of the Zg* production with the L3 detector. The cross-section average over the whole data sample was found to be: s&parl0;e+e-→Zg *→l+...
Differential realizations of the two-mode bosonic and fermionic ...
Indian Academy of Sciences (India)
Differential realizations of the two-mode bosonic and fermionic Hamiltonians: A unified approach ... Two mode bosonic 2 x2 matrix Hamiltonians play an important role in non-linear quantum optical systems. .... The validity of the procedure depends on the choice of a , β , 7 and Ж . One can easily obtain various physical ...
Mediation of entanglement and nonlocality of a single fermion
Bernardo, Bertúlio de Lima
2018-01-01
Entanglement is one of the most distinctive features of quantum mechanics and is now considered a fundamental resource in quantum information processing, such as in the protocols of quantum teleportation and quantum key distribution. In general, to extract its power in a useful form, it is necessary to generate entanglement between two or more quantum systems separated by long distances, which is not an easy task due to its fragility under environmental disturbance. Here, we propose a method to create entanglement between two distant fermionic particles, which never interact directly by using a third fermion to mediate the correlation. The protocol initiates with three indistinguishable fermions in a separable state, which are allowed to interact in pairs according to the Hong-Ou-Mandel effect. As a result, it is demonstrated that bipartite maximally entangled states can be generated with an efficiency of about 56%, which makes the method a potential candidate for practical quantum information applications. Furthermore, we use the same protocol to show how the mediator fermion exhibits nonlocal properties, giving a new insight on the long-standing discussion about nonlocality of a single particle.
Mean square number fluctuation for a fermion source and its ...
Indian Academy of Sciences (India)
Mean square number fluctuation for a fermion source and its dependence on neutrino mass for the universal cosmic neutrino background ... Using the general formulation for obtaining chemical potential of an ideal Fermi gas of particles at temperature , with particle rest mass m 0 and average density ⟨ N ⟩ / V , the ...
Fermionic coherent states for pseudo-Hermitian two-level systems
Energy Technology Data Exchange (ETDEWEB)
Cherbal, O [Physical Faculty, Theoretical Physics Lab, USTHB, BP 32 El-Alia, Bab Ezzouar, 16111 Algiers (Algeria); Drir, M [Physical Faculty, Theoretical Physics Lab, USTHB, BP 32 El-Alia, Bab Ezzouar, 16111 Algiers (Algeria); Maamache, M [Laboratoire de Physique Quantique et Systemes Dynamiques, Department of Physics, Setif University, Setif 19000 (Algeria); Trifonov, D A [Institute of Nuclear Research, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria)
2007-02-23
We introduce creation and annihilation operators of pseudo-Hermitian fermions for two-level systems described by a pseudo-Hermitian Hamiltonian with real eigenvalues. This allows the generalization of the fermionic coherent states approach to such systems. Pseudo-fermionic coherent states are constructed as eigenstates of two pseudo-fermion annihilation operators. These coherent states form a bi-normal and bi-overcomplete system, and their evolution governed by the pseudo-Hermitian Hamiltonian is temporally stable. In terms of the introduced pseudo-fermion operators, the two-level system Hamiltonian takes a factorized form similar to that of a harmonic oscillator.
Spin-k/2-spin-k/2 SU(2) two-point functions on the torus
Energy Technology Data Exchange (ETDEWEB)
Kirsch, Ingo [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie; Kucharski, Piotr [Warsaw Univ. (Poland). Inst. of Theoretical Physics
2012-11-15
We discuss a class of two-point functions on the torus of primary operators in the SU(2) Wess-Zumino-Witten model at integer level k. In particular, we construct an explicit expression for the current blocks of the spin-(k)/(2)-spin-(k)/(2) torus two-point functions for all k. We first examine the factorization limits of the proposed current blocks and test their monodromy properties. We then prove that the current blocks solve the corresponding Knizhnik-Zamolodchikov-like differential equations using the method of Mathur, Mukhi and Sen.
SU(2 color NJL model and EOS of quark-hadron matter at finite temperature and density
Directory of Open Access Journals (Sweden)
Weise Wolfram
2012-02-01
Full Text Available We study the NJL model with the Polyakov loop in the SU(2-color case for the EOS of quark-hadron matter at finite temperature and density. We consider the spontaneous chiral symmetry breaking and the diquark condensation together with the behavior of the Polyakov loop for the phase diagram of quark-hadron matter. We discuss the spectrum of mesons and diquark baryons (boson at finite temperature and density.We derive also the linear sigma model Lagrangian for diquark baryon and mesons.
A note on open-chain transfer matrices from q-deformed su(2 vertical stroke 2)S-matrices
Energy Technology Data Exchange (ETDEWEB)
Murgan, R. [Physics Department, Gustavus Adolphus College, St. Peter, MN (United States)
2009-09-15
In this note, we perform Sklyanin's construction of commuting open-chain/boundary transfer matrices to the q-deformed SU(2 vertical stroke 2) bulk S-matrix of Beisert and Koroteev and a corresponding boundary S-matrix. This also includes a corresponding commuting transfer matrix using the graded version of the q-deformed bulk S-matrix. Utilizing the crossing property for the bulk S-matrix, we argue that the transfer matrix for both graded and non-graded versions contains a crucial factor which is essential for commutativity. (Abstract Copyright [2009], Wiley Periodicals, Inc.)
Non-Abelian statistics of vortices with non-Abelian Dirac fermions.
Yasui, Shigehiro; Hirono, Yuji; Itakura, Kazunori; Nitta, Muneto
2013-05-01
We extend our previous analysis on the exchange statistics of vortices having a single Dirac fermion trapped in each core to the case where vortices trap two Dirac fermions with U(2) symmetry. Such a system of vortices with non-Abelian Dirac fermions appears in color superconductors at extremely high densities and in supersymmetric QCD. We show that the exchange of two vortices having doublet Dirac fermions in each core is expressed by non-Abelian representations of a braid group, which is explicitly verified in the matrix representation of the exchange operators when the number of vortices is up to four. We find that the result contains the matrices previously obtained for the vortices with a single Dirac fermion in each core as a special case. The whole braid group does not immediately imply non-Abelian statistics of identical particles because it also contains exchanges between vortices with different numbers of Dirac fermions. However, we find that it does contain, as its subgroup, genuine non-Abelian statistics for the exchange of the identical particles, that is, vortices with the same number of Dirac fermions. This result is surprising compared with conventional understanding because all Dirac fermions are defined locally at each vortex, unlike the case of Majorana fermions for which Dirac fermions are defined nonlocally by Majorana fermions located at two spatially separated vortices.
State sum constructions of spin-TFTs and string net constructions of fermionic phases of matter
Bhardwaj, Lakshya; Gaiotto, Davide; Kapustin, Anton
2017-04-01
It is possible to describe fermionic phases of matter and spin-topological field theories in 2+1 d in terms of bosonic "shadow" theories, which are obtained from the original theory by "gauging fermionic parity". The fermionic/spin theories are recovered from their shadow by a process of fermionic anyon condensation: gauging a one-form symmetry generated by quasi-particles with fermionic statistics. We apply the formalism to theories which admit gapped boundary conditions. We obtain Turaev-Viro-like and Levin-Wen-like constructions of fermionic phases of matter. We describe the group structure of fermionic SPT phases protected by ℤ 2 f × G. The quaternion group makes a surprise appearance.
Constantinou, Martha; Frezzotti, Roberto; Lubicz, Vittorio; Panagopoulos, Haralambos; Skouroupathis, Apostolos; Stylianou, Fotos
2010-01-01
In this work we calculate the corrections to the amputated Green's functions of 4-fermion operators, in 1-loop Lattice Perturbation theory. One of the novel aspects of our calculations is that they are carried out to O(a^2) (a: lattice spacing). We employ the Wilson/clover action for massless fermions (also applicable for the twisted mass action in the chiral limit) and a family of Symanzik improved actions for gluons. Our calculations have been carried out in a general covariant gauge. Results have been obtained for several popular choices of values for the Symanzik coefficients. While our Green's function calculations regard any pointlike 4-fermion operators which do not mix with lower dimension ones, we pay particular attention to DF=2 operators, both Parity Conserving and Parity Violating (F: flavour). We compute the perturbative renormalization constants for a complete basis of 4-fermion operators and we study their mixing pattern. For some of the actions considered here, even O(a^0) results did not exis...
Two-color QCD with staggered fermions at finite temperature under the influence of a magnetic field
Ilgenfritz, E -M; Muller-Preussker, M; Petersson, B; Schreiber, A
2012-01-01
In this paper we investigate the influence of a constant external magnetic field on the finite-temperature phase structure and the chiral properties of a simplified lattice model for QCD. We assume an SU(2) gauge symmetry and employ dynamical staggered fermions of identical mass without rooting, corresponding to Nf=4 flavors of identical electric charge. For fixed mass (given in lattice units) the critical temperature is seen to rise with the magnetic field strength. For three fixed beta-values, selected such that we stay (i) within the chirally broken phase, (ii) within the transition region or (iii) within the chirally restored phase, we study the approach to the chiral limit for various values of the magnetic field. Within the chirally broken (confinement) phase the chiral condensate is found to increase monotonically with a growing magnetic field strength. In the chiral limit the increase starts linear in agreement with a chiral model studied by Shushpanov and Smilga. Within the chirally restored (deconfi...
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
Vacuum Cherenkov radiation for Lorentz-violating fermions
Schreck, M.
2017-11-01
The current work focuses on the process of vacuum Cherenkov radiation for Lorentz-violating fermions that are described by the minimal standard-model extension (SME). To date, most considerations of this important hypothetical process have been restricted to Lorentz-violating photons, as the necessary theoretical tools for the SME fermion sector have not been available. With their development in a very recent paper, we are now in a position to compute the decay rates based on a modified Dirac theory. Two realizations of the Cherenkov process are studied. In the first scenario, the spin projection of the incoming fermion is assumed to be conserved, and in the second, the spin projection is allowed to flip. The first type of process is shown to be still forbidden for the dimensionful a and b coefficients where there are strong indications that it is energetically disallowed for the H coefficients, as well. However, it is rendered possible for the dimensionless c , d , e , f , and g coefficients. For large initial fermion energies, the decay rates for the c and d coefficients were found to grow linearly with momentum and to be linearly suppressed by the smallness of the Lorentz-violating coefficient where for the e , f , and g coefficients this suppression is even quadratic. The decay rates vanish in the vicinity of the threshold, as expected. The decay including a fermion spin-flip plays a role for the spin-nondegenerate operators and it was found to occur for the dimensionful b and H coefficients as well as for the dimensionless d and g . The characteristics of this process differ much from the properties of the spin-conserving one, e.g., there is no threshold. Based on experimental data of ultra-high-energy cosmic rays, new constraints on Lorentz violation in the quark sector are obtained from the thresholds. However, it does not seem to be possible to derive bounds from the spin-flip decays. This work reveals the usefulness of the quantum field theoretic methods
Development of the SAIT single-port surgical access robot--slave arm based on RCM mechanism.
Roh, Se-gon; Lee, Younbaek; Lee, Jongwon; Ha, Taesin; Sang, Taejun; Moon, Kyung-Won; Lee, Minhyong; Choi, Jung-yun
2015-01-01
An innovative single-port surgical robot has recently been developed by the Samsung Advanced Institute of Technology (SAIT). The robot can reach various surgical sites inside the abdominal cavity from a single incision on the body. It has two 7-DOF surgical tools, a 3-DOF endoscope, a flexible hyper-redundant 6-DOF guide tube, and a 6-DOF manipulator. This paper primarily focuses on the manipulator, called a slave arm, which is capable of setting the location of a Remote Center Motion (RCM) point. Because the surgical tools can explore the abdominal area through a small incision point when the RCM point is aligned with the incision area, the RCM mechanism is an integral part of the manipulator for single-port surgery. The mechanical feature, operational principle, control method, and the system architecture of the slave arm are introduced in this paper. In addition, manipulation experiments conducted validate its efficacy.
Directory of Open Access Journals (Sweden)
Seung-Woon Lee
2016-10-01
Full Text Available In this paper, we analyze one of the main drawbacks of droop control-based DC microgrid systems, and propose a novel control method to overcome this problem. Typically, DC microgrid systems use droop control techniques to enable communication independency and expandability. However, as these advantages are based on bus quality and regulation abandonment, droop-based schemes have limitations in terms of high bus impedance and bus regulation. This paper proposes a novel master–slave based hierarchical control technique for a DC distribution system, in which a DC bus signaling method is used to overcome the communication dependency and the expandability limitations of conventional master–slave control methods. The concept and design considerations of the proposed control method are presented, and a 1 kW simulation under a Powersim (PSIM environment and hardware prototype—built to verify the system—is described.
Energy Technology Data Exchange (ETDEWEB)
Ferling, Alexander
2009-05-29
A main topic of this thesis was to transfer the hybrid Monte-Carlo algorithm on a N=1 supersymmetric model. As model served the two-step multi-boson algorithm (TSMB). Beside the essential algorithm in the TSMB program further optimizations were realized. A further step was to optimize the lattice action so that discretization artefacts at finite lattice parameters were more strongly suppressed.
Coelho, C.; Navega, D.; Cunha, E.; Ferreira, M. T.; Wasterlain, S. N.
2017-01-01
In 2009, a skeletal collection of 158 individuals was excavated in Valle da Gafaria, Lagos, Portugal. These individuals were buried in an unusual way, having been discarded in an urban dump located outside the medieval city walls, dated from the 15th-17th centuries. Lagos was, at the time, an important slave trade harbour, and during the excavation, the morphological appearance of the skulls and the presence of intentionally modified teeth in some individuals raised suspicion that they were A...
Directory of Open Access Journals (Sweden)
Ana Lucia Araújo
2009-06-01
Full Text Available O artigo examina as diferentes representações da escravidão e do tráfico atlântico presentes na Rota dos Escravos da cidade de Ajudá, na atual República do Benim. Busca-se entender como estas representações exprimem e reconstroem diferentes memórias do passado escravista atlântico. Tenta-se mostrar que a Rota dos Escravos é um lugar construído, onde se percebem duas imagens do escravo, a da vítima absoluta e a do resistente. O percurso proposto sugere dois níveis de leitura: de um lado, os monumentos constituem uma encenação, cujo objetivo é emocionar os descendentes da diáspora (principalmente os norteamericanos, que têm recursos financeiros para fazer turismo em países estrangeiros; de outro lado, as estátuas concebidas pelo artista Cyprien Tokoudagaba e os templos existentes na Rota dos Escravos posicionam o visitante no cruzamento de diferentes memórias e diferentes histórias da escravidão, onde a vitimização dá lugar à afirmação cultural que valoriza a arte, as religiões e as culturas africanas.This paper examines the different representations of slavery and the slave trade found on the Slaves Route in Ouidah, present Republic of Benin. It aims at understanding how these representations express and reconstruct different memories of the Atlantic slave past. The paper shows that Ouidah's Slaves Route is a constructed space, where we can find two different images of enslaved Africans: the absolute victim and the resister. The proposed itinerary suggests two levels of interpretation: on the one hand, the monuments staging the past aim at emotionally move the diaspora (especially African Americans who have the financial resources to travel abroad; on the other hand, the statues conceived by Cyprien Tokoudagaba and the existing vodun temples on the Slaves Route place the visitor at the crossing position between different memories and different histories of slavery, where victimization is replaced by cultural
A Passive Parallel Master-Slave Mechanism for Magnetic Resonance Imaging-Guided Interventions.
Elayaperumal, Santhi; Cutkosky, Mark R; Renaud, Pierre; Daniel, Bruce L
2015-03-01
A passive, parallel master-slave mechanism is presented for magnetic resonance imaging (MRI)-guided interventions in the pelvis. The mechanism allows a physician to stand outside the MRI scanner while manipulating a needle inside the bore and, unlike a powered robot, does not place actuators in proximity to the patient. The manipulator combines two parallel mechanisms based on the Delta robot architecture. The mechanism also includes a two-axis gimbal to allow for tool angulation, giving a total of five degrees of freedom so that the physician can insert and steer a needle using continuous natural arm and wrist movements, unlike simple needle guides. The need for access between the patient's legs and within the MRI scanner leads to an unusual asymmetric design in which the sliding prismatic joints form the vertices of an isosceles triangle. Kinematic analysis shows that the dexterity index of this design is improved over the desired workspace, as compared to an equilateral design. The analysis is extended to estimate the effect of friction and model the input:output force transmission. Prototypes, with final dimensions selected for transperineal prostate interventions, showed force transmission behavior as predicted by simulation, and easily withstood maximum forces required for tool insertion.
Wilson, Jason T; Gerber, Matthew J; Prince, Stephen W; Chen, Cheng-Wei; Schwartz, Steven D; Hubschman, Jean-Pierre; Tsao, Tsu-Chin
2018-02-01
Since the advent of robotic-assisted surgery, the value of using robotic systems to assist in surgical procedures has been repeatedly demonstrated. However, existing technologies are unable to perform complete, multi-step procedures from start to finish. Many intraocular surgical steps continue to be manually performed. An intraocular robotic interventional surgical system (IRISS) capable of performing various intraocular surgical procedures was designed, fabricated, and evaluated. Methods were developed to evaluate the performance of the remote centers of motion (RCMs) using a stereo-camera setup and to assess the accuracy and precision of positioning the tool tip using an optical coherence tomography (OCT) system. The IRISS can simultaneously manipulate multiple surgical instruments, change between mounted tools using an onboard tool-change mechanism, and visualize the otherwise invisible RCMs to facilitate alignment of the RCM to the surgical incision. The accuracy of positioning the tool tip was measured to be 0.205±0.003 mm. The IRISS was evaluated by trained surgeons in a remote surgical theatre using post-mortem pig eyes and shown to be effective in completing many key steps in a variety of intraocular surgical procedures as well as being capable of performing an entire cataract extraction from start to finish. The IRISS represents a necessary step towards fully automated intraocular surgery and demonstrated accurate and precise master-slave manipulation for cataract removal and-through visual feedback-retinal vein cannulation. Copyright © 2017 John Wiley & Sons, Ltd.
4 Channel Slave Direct-Digital-Synthesizer – SDDS (EDA-00992)
BLAS, A; DELONG, J
2011-01-01
A novel rf beam control architecture has been successfully tested in the LEIR synchrotron. The design is based on a VME 64X carrier board, including a DSP (digital signal processor), into which different daughter cards can be plugged in. The SDDS (Slave Direct Digital Synthesizer) is one of them. Hardware wise it has the features of a four-channel DAC (digital-to-analogue converter) which inputs are driven by a powerful FPGA (field programmable logic array); the latter is connected to the DSP on the carrier board via high-speed connectors. Mainly, this unit will supply the rf signals driving the cavities at a specified harmonic of the revolution. The main sampling clock feeding the mezzanine board is at a high harmonic of the particle’s revolution frequency. In the PSB, this frequency is varying along the accelerating cycle and this choice allows creating the rf signal feeding the accelerating cavities without changing any parameter along the cycle. The sampling clock is tagged at the revolution rate allowi...
Inhomogeneous disorder Dirac Fermions: from heavy fermion superconductors to graphene. Final report
Energy Technology Data Exchange (ETDEWEB)
Vekhter, Ilya [Louisiana State University
2013-08-11
This is the final report on the award designed to foster a partnership between Louisiana State University and Los Alamos National Laboratory (LANL) in conducting fundamental research in support of energy needs. The general focus of the research effort was on developing a better understanding of materials with new functionalities. We investigated two distinct and very promising classes of new materials, which serve as a testing ground for many of the novel phenomena in condensed matter physics: the heavy fermion 115 series, where the interplay of strong interactions between the electrons leads to a rich variety of competing phases and anomalous properties, and newly discovered pnictide superconductors. The former focus was planned; the latter emerged during the collaborative effort with LANL. Our objective was to determine the origin, and to establish a functional effective theory description of the phases in these systems, and transitions between them. We report on the main accomplishments under the award that serves to clarify the nature of superconductivity in both families of materials. In particular, we collaborated with experimentalists to predict and analyze the magnetic field and temperature dependence of the bulk thermodynamic and transport properties and to determine the gap shape in CeCoIn₅ and in Ba(Fe_{1-x}Co_{x})₂As₂, investigated the Kondo temperature in the presence of spin-orbit coupling in the conduction band, and provided theoretical guidance for local probes such as scanning tunneling spectroscopy of vortex cores and impurity resonances, and magnetic force microscopy of the superconducting states.
Multi-boson block factorization of fermions arXiv
Giusti, Leonardo; Schaefer, Stefan
The numerical computations of many quantities of theoretical and phenomenological interest are plagued by statistical errors which increase exponentially with the distance of the sources in the relevant correlators. Notable examples are baryon masses and matrix elements, the hadronic vacuum polarization and the light-by-light scattering contributions to the muon g-2, and the form factors of semileptonic B decays. Reliable and precise determinations of these quantities are very difficult if not impractical with state-of-the-art standard Monte Carlo integration schemes. I will review a recent proposal for factorizing the fermion determinant in lattice QCD that leads to a local action in the gauge field and in the auxiliary boson fields. Once combined with the corresponding factorization of the quark propagator, it paves the way for multi-level Monte Carlo integration in the presence of fermions opening new perspectives in lattice QCD. Exploratory results on the impact on the above mentioned observables will be ...
Search for composite and exotic fermions at LEP 2
Abreu, P.; Adye, T.; Adzic, P.; Alderweireld, T.; Alekseev, G.D.; Alemany, R.; Allmendinger, T.; Allport, P.P.; Almehed, S.; Amaldi, U.; Amato, S.; Anassontzis, E.G.; Andersson, P.; Andreazza, A.; Andringa, S.; Antilogus, P.; Apel, W.D.; Arnoud, Y.; Asman, B.; Augustin, J.E.; Augustinus, A.; Baillon, P.; Bambade, P.; Barao, F.; Barbiellini, G.; Barbier, R.; Bardin, D.Yu.; Barker, G.J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.H.; Begalli, M.; Beilliere, P.; Belokopytov, Yu.; Benvenuti, A.C.; Berat, C.; Berggren, M.; Bertini, D.; Bertrand, D.; Besancon, M.; Bianchi, F.; Bigi, M.; Bilenky, Mikhail S.; Bizouard, M.A.; Bloch, D.; Blom, H.M.; Bonesini, M.; Bonivento, W.; Boonekamp, M.; Booth, P.S.L.; Borgland, A.W.; Borisov, G.; Bosio, C.; Botner, O.; Boudinov, E.; Bouquet, B.; Bourdarios, C.; Bowcock, T.J.V.; Boyko, I.; Bozovic, I.; Bozzo, M.; Branchini, P.; Brenke, T.; Brenner, R.A.; Bruckman, P.; Brunet, J.M.; Bugge, L.; Buran, T.; Burgsmuller, T.; Buschmann, P.; Cabrera, S.; Caccia, M.; Calvi, M.; Camacho Rozas, A.J.; Camporesi, T.; Canale, V.; Carena, F.; Carroll, L.; Caso, C.; Castillo Gimenez, M.V.; Cattai, A.; Cavallo, F.R.; Cerruti, C.; Chabaud, V.; Chapkin, M.; Charpentier, P.; Chaussard, L.; Checchia, P.; Chelkov, G.A.; Chierici, R.; Chliapnikov, P.; Chochula, P.; Chorowicz, V.; Chudoba, J.; Collins, P.; Colomer, M.; Contri, R.; Cortina, E.; Cosme, G.; Cossutti, F.; Cowell, J.H.; Crawley, H.B.; Crennell, D.; Crosetti, G.; Cuevas Maestro, J.; Czellar, S.; Damgaard, G.; Davenport, M.; Da Silva, W.; Deghorain, A.; Della Ricca, G.; Delpierre, P.; Demaria, N.; De Angelis, A.; De Boer, W.; De Brabandere, S.; De Clercq, C.; De Lotto, B.; De Min, A.; De Paula, L.; Dijkstra, H.; Di Ciaccio, L.; Di Diodato, A.; Dolbeau, J.; Doroba, K.; Dracos, M.; Drees, J.; Dris, M.; Duperrin, A.; Durand, J.D.; Eigen, G.; Ekelof, T.; Ekspong, G.; Ellert, M.; Elsing, M.; Engel, J.P.; Erzen, B.; Espirito Santo, M.C.; Harris, Elisabeth Falk; Fanourakis, G.; Fassouliotis, D.; Fayot, J.; Feindt, M.; Fenyuk, A.; Ferrari, P.; Ferrer, A.; Ferrer-Ribas, E.; Fichet, S.; Firestone, A.; Fischer, P.A.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fontanelli, F.; Franek, B.; Frodesen, A.G.; Fruhwirth, R.; Fulda-Quenzer, F.; Fuster, J.; Galloni, A.; Gamba, D.; Gamblin, S.; Gandelman, M.; Garcia, C.; Garcia, J.; Gaspar, C.; Gaspar, M.; Gasparini, U.; Gavillet, P.; Gazis, Evangelos; Gele, D.; Gerber, J.P.; Gerdyukov, L.; Ghodbane, N.; Gil Botella, Ines; Glege, F.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Gonzalez Caballero, I.; Gopal, G.; Gorn, L.; Gorski, M.; Gouz, Yu.; Gracco, V.; Grahl, J.; Graziani, E.; Green, C.; Grimm, H.J.; Gris, P.; Grzelak, K.; Gunther, M.; Guy, J.; Hahn, F.; Hahn, S.; Haider, S.; Hallgren, A.; Hamacher, K.; Harris, F.J.; Hedberg, V.; Heising, S.; Hernandez, J.J.; Herquet, P.; Herr, H.; Hessing, T.L.; Heuser, J.M.; Higon, E.; Holmgren, S.O.; Holt, P.J.; Holthuizen, D.; Hoorelbeke, S.; Houlden, M.; Hrubec, J.; Huet, K.; Hultqvist, K.; Jackson, John Neil; Jacobsson, R.; Jalocha, P.; Janik, R.; Jarlskog, C.; Jarlskog, G.; Jarry, P.; Jean-Marie, B.; Johansson, Erik Karl; Jonsson, P.; Joram, C.; Juillot, P.; Kapusta, Frederic; Karafasoulis, K.; Katsanevas, S.; Katsoufis, E.C.; Keranen, R.; Khomenko, B.A.; Khovansky, N.N.; Kiiskinen, A.; King, B.; Kjaer, N.J.; Klapp, O.; Klein, Hansjorg; Kluit, P.; Kokkinias, P.; Koratzinos, M.; Kostioukhine, V.; Kourkoumelis, C.; Kouznetsov, O.; Krammer, M.; Kreuter, C.; Kriznic, E.; Krstic, J.; Krumshtein, Z.; Kubinec, P.; Kucewicz, W.; Kurvinen, K.; Lamsa, J.W.; Lane, D.W.; Langefeld, P.; Lapin, V.; Laugier, J.P.; Lauhakangas, R.; Leder, G.; Ledroit, Fabienne; Lefebure, V.; Leinonen, L.; Leisos, A.; Leitner, R.; Lenzen, G.; Lepeltier, V.; Lesiak, T.; Lethuillier, M.; Libby, J.; Liko, D.; Lipniacka, A.; Lippi, I.; Lorstad, B.; Loken, J.G.; Lopes, J.H.; Lopez, J.M.; Lopez-Fernandez, R.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Mahon, J.R.; Maio, A.; Malek, A.; Malmgren, T.G.M.; Malychev, V.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Martinez-Vidal, F.; Marti i Garcia, S.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Matthiae, G.; Mazik, J.; Mazzucato, F.; Mazzucato, M.; McCubbin, M.; McKay, R.; McNulty, R.; McPherson, G.; Meroni, C.; Meyer, W.T.; Migliore, E.; Mirabito, L.; Mitaroff, W.A.; Mjoernmark, U.; Moa, T.; Moller, Rasmus; Monig, Klaus; Monge, M.R.; Moreau, X.; Morettini, P.; Morton, G.; Muller, U.; Muenich, K.; Mulders, M.; Mulet-Marquis, C.; Muresan, R.; Murray, W.J.; Muryn, B.; Myatt, G.; Myklebust, T.; Naraghi, F.; Navarria, F.L.; Navas, Sergio; Nawrocki, K.; Negri, P.; Neufeld, N.; Neumeister, N.; Nicolaidou, R.; Nielsen, B.S.; Nikolaenko, V.; Nikolenko, M.; Nomokonov, V.; Normand, A.; Nygren, A.; Obraztsov, V.; Olshevski, A.G.; Onofre, A.; Orava, R.; Orazi, G.; Osterberg, K.; Ouraou, A.; Paganoni, M.; Paiano, S.; Pain, R.; Paiva, R.; Palacios, J.; Palka, H.; Papadopoulou, T.D.; Papageorgiou, K.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Pegoraro, M.; Peralta, L.; Pernicka, M.; Perrotta, A.; Petridou, C.; Petrolini, A.; Phillips, H.T.; Piana, G.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Pol, M.E.; Polok, G.; Poropat, P.; Pozdniakov, V.; Privitera, P.; Pukhaeva, N.; Pullia, A.; Radojicic, D.; Ragazzi, S.; Rahmani, H.; Rakoczy, D.; Rames, J.; Ratoff, P.N.; Read, Alexander L.; Rebecchi, P.; Redaelli, Nicola Giuseppe; Regler, M.; Reid, D.; Reinhardt, R.; Renton, P.B.; Resvanis, L.K.; Richard, F.; Ridky, J.; Rinaudo, G.; Rohne, O.; Romero, A.; Ronchese, P.; Rosenberg, E.I.; Rosinsky, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ruiz, A.; Saarikko, H.; Sacquin, Y.; Sadovsky, A.; Sajot, G.; Salt, J.; Sampsonidis, D.; Sannino, M.; Schneider, H.; Schwemling, P.; Schwickerath, U.; Schyns, M.A.E.; Scuri, Fabrizio; Seager, P.; Sedykh, Yu.; Segar, A.M.; Sekulin, R.; Shellard, R.C.; Sheridan, A.; Siebel, M.; Silvestre, R.; Simard, L.; Simonetto, F.; Sisakian, A.N.; Skaali, T.B.; Smadja, G.; Smirnov, N.; Smirnova, O.; Smith, G.R.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Spiriti, E.; Sponholz, P.; Squarcia, S.; Stanescu, C.; Stanic, S.; Stapnes, S.; Stevenson, K.; Stocchi, A.; Strauss, J.; Strub, R.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Tabarelli, T.; Tegenfeldt, F.; Terranova, F.; Thomas, J.; Tilquin, A.; Timmermans, Jan; Tkachev, L.G.; Todorov, T.; Todorova, S.; Toet, D.Z.; Tomaradze, A.; Tome, B.; Tonazzo, A.; Tortora, L.; Transtromer, G.; Treille, D.; Tristram, G.; Troncon, C.; Tsirou, A.; Turluer, M.L.; Tyapkin, I.A.; Tzamarias, S.; Uberschar, B.; Ullaland, O.; Uvarov, V.; Valenti, G.; Vallazza, E.; Van Apeldoorn, G.W.; Van Dam, Piet; Van Eldik, J.; Van Lysebetten, A.; Van Vulpen, I.; Vassilopoulos, N.; Vegni, G.; Ventura, L.; Venus, W.; Verbeure, F.; Verlato, M.; Vertogradov, L.S.; Verzi, V.; Vilanova, D.; Vitale, L.; Vlasov, E.; Vodopianov, A.S.; Vollmer, C.; Voulgaris, G.; Vrba, V.; Wahlen, H.; Walck, C.; Weiser, C.; Wicke, D.; Wickens, J.H.; Wilkinson, G.R.; Winter, M.; Witek, M.; Wolf, G.; Yi, J.; Yushchenko, O.; Zaitsev, A.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zevgolatakos, E.; Zimine, N.I.; Zucchelli, G.C.; Zumerle, G.
1999-01-01
A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48~pb$^{-1}$ at an $e^+e^-$ centre-of-mass energy of 183~GeV and about 20~pb$^{-1}$ equally shared between the centre-of-mass energies of 172~GeV and 161~GeV. The search for pair-produced new leptons establishes 95\\% confidence level mass limits in the region between 70~GeV/$c^2$ and 90~GeV/$c^2$, depending on the channel. The search for singly produced excited leptons and quarks establishes upper limits on the ratio of the coupling of the excited fermion
Grassmann phase space methods for fermions. I. Mode theory
Dalton, B. J.; Jeffers, J.; Barnett, S. M.
2016-07-01
In both quantum optics and cold atom physics, the behaviour of bosonic photons and atoms is often treated using phase space methods, where mode annihilation and creation operators are represented by c-number phase space variables, with the density operator equivalent to a distribution function of these variables. The anti-commutation rules for fermion annihilation, creation operators suggest the possibility of using anti-commuting Grassmann variables to represent these operators. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of Grassmann phase space methods in quantum-atom optics to treat fermionic systems is rather rare, though fermion coherent states using Grassmann variables are widely used in particle physics. The theory of Grassmann phase space methods for fermions based on separate modes is developed, showing how the distribution function is defined and used to determine quantum correlation functions, Fock state populations and coherences via Grassmann phase space integrals, how the Fokker-Planck equations are obtained and then converted into equivalent Ito equations for stochastic Grassmann variables. The fermion distribution function is an even Grassmann function, and is unique. The number of c-number Wiener increments involved is 2n2, if there are n modes. The situation is somewhat different to the bosonic c-number case where only 2 n Wiener increments are involved, the sign of the drift term in the Ito equation is reversed and the diffusion matrix in the Fokker-Planck equation is anti-symmetric rather than symmetric. The un-normalised B distribution is of particular importance for determining Fock state populations and coherences, and as pointed out by Plimak, Collett and Olsen, the drift vector in its Fokker-Planck equation only depends linearly on the Grassmann variables. Using this key feature we show how the Ito stochastic equations can be solved numerically for finite times in terms of c-number stochastic
Unconventional superfluids of fermionic polar molecules in a bilayer system
Energy Technology Data Exchange (ETDEWEB)
Boudjemâa, Abdelâali, E-mail: a.boudjemaa@univhb-chlef.dz
2017-05-25
We study unconventional superfluids of fermionic polar molecules in a two-dimensional bilayer system with dipoles are head-to-tail across the layers. We analyze the critical temperature of several unconventional pairings as a function of different system parameters. The peculiar competition between the d- and the s-wave pairings is discussed. We show that the experimental observation of such unconventional superfluids requires ultralow temperatures, which opens up new possibilities to realize several topological phases. - Highlights: • Investigation of novel superfluids of fermionic polar molecules in a bilayer geometry. • Solving the gap equation and the l-wave interlayer scattering problem. • Calculation of the critical temperature of several competing pairings using the BCS approach.
Creating a bosonic fractional quantum Hall state by pairing fermions
Repellin, Cécile; Yefsah, Tarik; Sterdyniak, Antoine
2017-10-01
We numerically study the behavior of spin-1 /2 fermions on a two-dimensional square lattice subject to a uniform magnetic field, where opposite spins interact via an on-site attractive interaction. Starting from the noninteracting case where each spin population is prepared in a quantum Hall state with unity filling, we follow the evolution of the system as the interaction strength is increased. Above a critical value and for sufficiently low flux density, we observe the emergence of a twofold quasidegeneracy accompanied by the opening of an energy gap to the third level. Analysis of the entanglement spectra shows that the gapped ground state is the bosonic 1 /2 Laughlin state. Our work therefore provides compelling evidence of a topological phase transition from the fermionic quantum Hall state at unity filling to the bosonic Laughlin state at a critical attraction strength of the order of the one-body spectrum linewidth.
Coulomb interaction effect in tilted Weyl fermion in two dimensions
Isobe, Hiroki; Nagaosa, Naoto
Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor α-(BEDT-TTF)2I3 and three-dimensional WTe2. The Coulomb interaction between electrons modifies the velocities in an essential way in the low energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the renormalization group equations for the velocities of the tilted Weyl fermions in two dimensions, and found that they increase as the energy decreases and eventually hit the velocity of light c to result in the Cherenkov radiation. Especially, the system restores the isotropic Weyl cone even when the bare Weyl cone is strongly tilted and the velocity of electrons becomes negative in certain directions.
Fermion perturbations in string-theory black holes
Piedra, Owen Pavel Fernández
2010-01-01
In this paper we study fermion perturbations in four dimensional black holes of string theory, obtained either from a non-extreme configuration of three intersecting five-branes with a boost along the common string or from a non-extreme intersecting system of two two-branes and two five-branes. The Dirac equation for the massless neutrino field, after conformal re-scaling of the metric, is written as a wave equation suitable to study the time evolution of the perturbation. With the aid of Prony fitting of time-domain profile we calculate the complex frequencies that dominate the quasinormal ringing stage, and also determine this quantities by the semi-analytical sixth order WKB method. We also find numerically the decay factor of fermion fields at very late times, and show that the falloff is identical to those appeared for massless fields in other four dimensional black hole spacetimes.
Fermion Monte Carlo Calculations on Liquid-3He
Energy Technology Data Exchange (ETDEWEB)
Kalos, M H; Colletti, L; Pederiva, F
2004-03-16
Methods and results for calculations of the ground state energy of the bulk system of {sup 3}He atoms are discussed. Results are encouraging: they believe that they demonstrate that their methods offer a solution of the ''fermion sign problem'' and the possibility of direct computation of many-fermion systems with no uncontrolled approximations. Nevertheless, the method is still rather inefficient compared with variational or fixed-node approximate methods. There appears to be a significant populations size effect. The situation is improved by the inclusion of ''Second Stage Importance Sampling'' and of ''Acceptance/Rejection'' adapted to their needs.
Thermal corrections to Rényi entropies for free fermions
Energy Technology Data Exchange (ETDEWEB)
Herzog, Christopher P.; Spillane, Michael [C.N. Yang Institute for Theoretical Physics, Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794 (United States)
2016-04-20
We calculate thermal corrections to Rényi entropies for free massless fermions on a sphere. More specifically, we take a free fermion on ℝ×S{sup d−1} and calculate the leading thermal correction to the Rényi entropies for a cap like region with opening angle 2θ. By expanding the density matrix in a Boltzmann sum, the problem of finding the Rényi entropies can be mapped to the problem of calculating a two point function on an n sheeted cover of the sphere. We follow previous work for conformal field theories to map the problem on the sphere to a conical region in Euclidean space. By using the method of images, we calculate the two point function and recover the Rényi entropies.
PT-Symmetric Real Dirac Fermions and Semimetals.
Zhao, Y X; Lu, Y
2017-02-03
Recently, Weyl fermions have attracted increasing interest in condensed matter physics due to their rich phenomenology originated from their nontrivial monopole charges. Here, we present a theory of real Dirac points that can be understood as real monopoles in momentum space, serving as a real generalization of Weyl fermions with the reality being endowed by the PT symmetry. The real counterparts of topological features of Weyl semimetals, such as Nielsen-Ninomiya no-go theorem, 2D subtopological insulators, and Fermi arcs, are studied in the PT symmetric Dirac semimetals and the underlying reality-dependent topological structures are discussed. In particular, we construct a minimal model of the real Dirac semimetals based on recently proposed cold atom experiments and quantum materials about PT symmetric Dirac nodal line semimetals.
On Some Troubles with the Metaphysics of Fermionic Compositions
Bigaj, Tomasz
2016-09-01
In this paper I discuss some metaphysical consequences of an unorthodox approach to the problem of the identity and individuality of "indistinguishable" quantum particles. This approach is based on the assumption that the only admissible way of individuating separate components of a given system is with the help of the permutation-invariant qualitative properties of the total system. Such a method of individuation, when applied to fermionic compositions occupying so-called GMW-nonentangled states, yields highly implausible consequences regarding the number of distinct components of a given composite system. I specify the problem (which I call the problem of fermionic inflation) in detail, and I consider several strategies of solving it. The preferred solution of the problem is based on the premise that spatial location should play a privileged role in identifying and making reference to quantum-mechanical systems.
Spin-excitons in heavy-fermion semimetals
Energy Technology Data Exchange (ETDEWEB)
Riseborough, Peter S., E-mail: prisebor@temple.edu [Temple University, Philadelphia (United States); Magalhaes, S.G. [Univ. Federal, Fluminense, Niteroi, Rio de Janeiro (Brazil)
2016-02-15
Spin-excitons are sharp and dispersive magnetic fluctuations in paramagnetic semiconductors where the dispersion relation lies within the semiconducting gap. Spin-excitons are found in the vicinity of magnetic quantum critical points in semiconductors, much the same as antiparamagnons are precursor fluctuations for quantum critical points in metals. Here we show that this concept of spin-exciton excitations can be extended to heavy-fermion semimetals and provides a natural explanation of the magnetic modes found by inelastic neutron scattering experiments on paramagnetic CeFe{sub 2}Al{sub 10}. - Highlights: • We discuss the theory of spin excitons in heavy-fermion semiconductors as precritical fluctuations. • We show that relatively sharp magnetic in-gap excitations can also occur in semiconductors. • The magnetic excitations are only sharp for a restricted range of center of mass momenta. • They may merge with the quasi-elastic peak associated with incommensurate nesting of electron and hole pockets.
Towards Quantum Turbulence in Cold Atomic Fermionic Superfluids
Bulgac, Aurel; Wlazłowski, Gabriel
2016-01-01
Fermionic superfluids provide a new realization of quantum turbulence, accessible to both experiment and theory, yet relevant to both cold atoms and nuclear astrophysics. In particular, the strongly interacting Fermi gas realized in cold-atom experiments is closely related to dilute neutron matter in the neutron star crust. Unlike the liquid superfluids 4He (bosons) and 3He (fermions), where quantum turbulence has been studied in laboratory for decades, quantum gases, and in particular superfluid Fermi gases stand apart for a number of reasons. Fermi gases admit a rather reliable microscopic description based on density functional theory which describes both static and dynamical phenomena. Cold atom experiments demonstrate exquisite control over particle number, spin polarization, density, temperature, and interacting strength. Topological defects such as domain walls and quantized vortices, which lie at the heart of quantum turbulence, can be created and manipulated with time-dependent external potentials, a...
Fermionic dark matter in a simple t-channel model
Energy Technology Data Exchange (ETDEWEB)
Goyal, Ashok; Kumar, Mukesh [National Institute for Theoretical Physics, School of Physics and Mandelstam Institute for Theoretical Physics, University of the Witwatersrand, Johannesburg, Wits 2050 (South Africa)
2016-11-02
We consider a fermionic dark matter (DM) particle in renormalizable Standard Model (SM) gauge interactions in a simple t-channel model. The DM particle interactions with SM fermions is through the exchange of scalar and vector mediators which carry colour or lepton number. In the case of coloured mediators considered in this study, we find that if the DM is thermally produced and accounts for the observed relic density almost the entire parameter space is ruled out by the direct detection observations. The bounds from the monojet plus missing energy searches at the Large Hadron Collider are less stringent in this case. In contrast for the case of Majorana DM, we obtain strong bounds from the monojet searches which rule out DM particles of mass less than about a few hundred GeV for both the scalar and vector mediators.
Majorana Fermions in Particle Physics, Solid State and Quantum Information
Borsten, L.; Duff, M. J.
This review is based on lectures given by M. J. Duff summarising the far reaching contributions of Ettore Majorana to fundamental physics, with special focus on Majorana fermions in all their guises. The theoretical discovery of the eponymous fcrmion in 1937 has since had profound implications for particlc physics, solid state and quantum computation. The breadth of these disciplines is testimony to Majorana's genius, which continues to permeate physics today. These lectures offer a whistle-stop tour through some limited subset of the key ideas. In addition to touching on these various applications, we will draw out some fascinating relations connecting the normed division algebras R, ℂ, H, O to spinors, trialities. K-theory and the classification of stable topological states of symmetry-protected gapped free-fermion systems.
Super Efimov effect of resonantly interacting fermions in two dimensions.
Nishida, Yusuke; Moroz, Sergej; Son, Dam Thanh
2013-06-07
We study a system of spinless fermions in two dimensions with a short-range interaction fine-tuned to a p-wave resonance. We show that three such fermions form an infinite tower of bound states of orbital angular momentum ℓ=±1 and their binding energies obey a universal doubly exponential scaling E(3)((n))∝exp(-2e(3πn/4+θ)) at large n. This "super Efimov effect" is found by a renormalization group analysis and confirmed by solving the bound state problem. We also provide an indication that there are ℓ=±2 four-body resonances associated with every three-body bound state at E(4)((n))∝exp(-2e(3πn/4+θ-0.188)). These universal few-body states may be observed in ultracold atom experiments and should be taken into account in future many-body studies of the system.
Note on the Lattice Fermion Chiral Symmetry Group
Mandula, Jeffrey E.
2007-01-01
The group structure of the variant chiral symmetry discovered by Luscher in the Ginsparg-Wilson description of lattice chiral fermions is analyzed. It is shown that the group contains an infinite number of linearly independent symmetry generators, and the Lie algebra is given explicitly. CP is an automorphism of the chiral group, and the CP transformation properties of the symmetry generators is found. Features of the currents associated with these symmetries are discussed, including the fact...
Thermal stitching: Extending the reach of quantum fermion solvers
Smith, Justin Clifford; Burke, Kieron
2018-01-01
For quantum fermion problems, many accurate solvers are limited by the temperature regime in which they can be usefully applied. The Mermin theorem implies the uniqueness of an effective potential from which both the exact density and free energy at a target temperature can be found, via a calculation at a different, reference temperature. We derive exact expressions for both the potential and the free energy in such a calculation, and introduce three controllable approximations that reduce t...
Mathieu functions for fermions generated in magnetar’s corona
Dariescu, Marina-Aura; Dariescu, Ciprian
2017-10-01
This work deals with the behavior of fermions in a configuration supposed to exist in magnetar’s corona. For a static magnetic induction parallel to a time-harmonic electric field, the solution to the U(1)-gauge invariant Dirac equation is expressed in terms of Laguerre polynomials and Mathieu’s functions of complex parameter. Using the Fourier series valid before the branching point, we are computing the conserved current density components.
Chaotic spin precession in anisotropic universes and fermionic dark matter
Kamenshchik, A Yu
2015-01-01
We consider the precession of a Dirac particle spin in some anisotropic Bianchi universes. This effect is present already in the Bianchi-I universe. In the Bianchi-IX universe it acquires the chaotic character due to the stochasticity of the oscillatory approach to the cosmological singularity. The related helicity flip of fermions in the very early Universe may produce the sterile particles contributing to dark matter.
Novel $p$-wave superfluids of fermionic polar molecules
Fedorov, A. K.; Matveenko, S. I.; Yudson, V. I.; Shlyapnikov, G. V.
2016-01-01
We show that recently suggested subwavelength lattices offer remarkable prospects for the observation of novel superfluids of fermionic polar molecules. It becomes realistic to obtain a topological $p$-wave superfluid of microwave-dressed polar molecules in 2D lattices at temperatures of the order of tens of nanokelvins, which is promising for topologically protected quantum information processing. Another foreseen novel phase is an interlayer $p$-wave superfluid of polar molecules in a bilay...
Novel p-wave superfluids of fermionic polar molecules.
Fedorov, A K; Matveenko, S I; Yudson, V I; Shlyapnikov, G V
2016-06-09
Recently suggested subwavelength lattices offer remarkable prospects for the observation of novel superfluids of fermionic polar molecules. It becomes realistic to obtain a topological p-wave superfluid of microwave-dressed polar molecules in 2D lattices at temperatures of the order of tens of nanokelvins, which is promising for topologically protected quantum information processing. Another foreseen novel phase is an interlayer p-wave superfluid of polar molecules in a bilayer geometry.
Majorana Fermions, Supersymmetry Breaking, and Born-Infeld Theory
Ferrara, Sergio; Yeranyan, Armen
2015-01-01
This review is devoted to highlight some aspects of the relevance of Majorana fermions in rigid supersymmetry breaking in four spacetime dimensions. After introducing some basic facts on spinors, and on their symmetries and reality properties, we consider Goldstino actions describing partial breaking of rigid supersymmetry, then focussing on Born-Infeld non-linear theory, its duality symmetry, and its supersymmetric extensions, also including multi-field generalizations exhibiting doubly self-duality.
Random matrix theory and the spectra of overlap fermions
Energy Technology Data Exchange (ETDEWEB)
Shcheredin, S.; Bietenholz, W.; Chiarappa, T.; Jansen, K.; Nagai, K.-I
2004-03-01
The application of Random Matrix Theory to the Dirac operator of QCD yields predictions for the probability distributions of the lowest eigenvalues. We measured Dirac operator spectra using massless overlap fermions in quenched QCD at topological charge {nu} = 0, {+-} 1 and {+-}2, and found agreement with those predictions -- at least for the first non-zero eigenvalue -- if the volume exceeds about (1.2 fm){sup 4}.
Diagrammatic Monte Carlo simulations of staggered fermions at finite coupling
Vairinhos, Helvio
2016-01-01
Diagrammatic Monte Carlo has been a very fruitful tool for taming, and in some cases even solving, the sign problem in several lattice models. We have recently proposed a diagrammatic model for simulating lattice gauge theories with staggered fermions at arbitrary coupling, which extends earlier successful efforts to simulate lattice QCD at finite baryon density in the strong-coupling regime. Here we present the first numerical simulations of our model, using worm algorithms.
QUANTUM STOCHASTIC PROCESSES: BOSON AND FERMION BROWNIAN MOTION
Directory of Open Access Journals (Sweden)
A.E.Kobryn
2003-01-01
Full Text Available Dynamics of quantum systems which are stochastically perturbed by linear coupling to the reservoir can be studied in terms of quantum stochastic differential equations (for example, quantum stochastic Liouville equation and quantum Langevin equation. In order to work it out one needs to define the quantum Brownian motion. As far as only its boson version has been known until recently, in the present paper we present the definition which makes it possible to consider the fermion Brownian motion as well.
Chiral symmetry on the lattice with Wilson fermions
Energy Technology Data Exchange (ETDEWEB)
Bochicchio, M.; Maiani, L.; Martinelli, G.; Rossi, G.; Testa, M.
1985-12-16
The chiral properties of the continuum limit of lattice QCD with Wilson fermions are studied. We show that a partially conserved axial current can be defined, satisfying the usual current algebra requirements. A proper definition of the chiral symmetry order parameter, <0 vertical stroke anti psi psi vertical stroke 0>, is given, and the chiral properties of composite operators are investigated. The implications of our analysis to the lattice determination of non-leptonic weak amplitudes are also discussed. (orig.).
Quantum Phase Liquids-Fermionic Superfluid without Phase Coherence
Wu, Ya-Jie; Zhou, Jiang; Kou, Su-Peng
2014-01-01
We investigate the two dimensional generalized attractive Hubbard model in a bipartite lattice, and and a "quantum phase liquid" phase, in which the fermions are paired but don't have phase coherence at zero temperature, in analogy to quantum spin liquid phase. Then, two types of topological quantum phase liquids with a small external magnetic field-Z2 quantum phase liquids and chiral quantum phase liquids-are discussed.
Ratchet potential and rectification effect in Majorana fermion SQUID
Wang, Zhi; Liang, Qi-Feng; Hu, Xiao
2012-01-01
Motivated by a recent experimental progress in realizing Majorana fermions (MFs) in a heterostructure of a spin-orbit coupling nanowire and superconductor (V. Mourik et al., Science.1222360), we investigate a SQUID formed by the novel superconductor-nanowire-superconductor Josephson junction which contains MFs and a conventional superconductor-insulator-superconductor junction. It is shown that the critical current of the SQUID is different for the two current directions. Since the asymmetric...
Fermionic currents in AdS spacetime with compact dimensions
Bellucci, S.; Saharian, A. A.; Vardanyan, V.
2017-09-01
We derive a closed expression for the vacuum expectation value (VEV) of the fermionic current density in a (D +1 )-dimensional locally AdS spacetime with an arbitrary number of toroidally compactified Poincaré spatial dimensions and in the presence of a constant gauge field. The latter can be formally interpreted in terms of a magnetic flux treading the compact dimensions. In the compact subspace, the field operator obeys quasiperiodicity conditions with arbitrary phases. The VEV of the charge density is zero and the current density has nonzero components along the compact dimensions only. They are periodic functions of the magnetic flux with the period equal to the flux quantum and tend to zero on the AdS boundary. Near the horizon, the effect of the background gravitational field is small and the leading term in the corresponding asymptotic expansion coincides with the VEV for a massless field in the locally Minkowski bulk. Unlike the Minkowskian case, in the system consisting of an equal number of fermionic and scalar degrees of freedom, with same masses, charges and phases in the periodicity conditions, the total current density does not vanish. In these systems, the leading divergences in the scalar and fermionic contributions on the horizon are canceled and, as a consequence of that, the charge flux, integrated over the coordinate perpendicular to the AdS boundary, becomes finite. We show that in odd spacetime dimensions the fermionic fields realizing two inequivalent representations of the Clifford algebra and having equal phases in the periodicity conditions give the same contribution to the VEV of the current density. Combining the contributions from these fields, the current density in odd-dimensional C -,P - and T -symmetric models are obtained. As an application, we consider the ground state current density in curved carbon nanotubes described in terms of a (2 +1 )-dimensional effective Dirac model.