Nonrelativistic Fermions in Magnetic Fields a Quantum Field Theory Approach
Espinosa, Olivier R; Lepe, S; Méndez, F
2001-01-01
The statistical mechanics of nonrelativistic fermions in a constant magnetic field is considered from the quantum field theory point of view. The fermionic determinant is computed using a general procedure that contains all possible regularizations. The nonrelativistic grand-potential can be expressed in terms polylogarithm functions, whereas the partition function in 2+1 dimensions and vanishing chemical potential can be compactly written in terms of the Dedekind eta function. The strong and weak magnetic fields limits are easily studied in the latter case by using the duality properties of the Dedekind function.
Renormalization group for non-relativistic fermions.
Shankar, R
2011-07-13
A brief introduction is given to the renormalization group for non-relativistic fermions at finite density. It is shown that Landau's theory of the Fermi liquid arises as a fixed point (with the Landau parameters as marginal couplings) and its instabilities as relevant perturbations. Applications to related areas, nuclear matter, quark matter and quantum dots, are briefly discussed. The focus will be on explaining the main ideas to people in related fields, rather than addressing the experts.
Energy shift of interacting non-relativistic fermions in noncommutative space
Directory of Open Access Journals (Sweden)
A. Jahan
2005-06-01
Full Text Available A local interaction in noncommutative space modifies to a non-local one. For an assembly of particles interacting through the contact potential, formalism of the quantum field theory makes it possible to take into account the effect of modification of the potential on the energy of the system. In this paper we calculate the energy shift of an assembly of non-relativistic fermions, interacting through the contact potential in the presence of the two-dimensional noncommutativity.
Isotropic Landau levels of relativistic and non-relativistic fermions in 3D flat space
Li, Yi; Wu, Congjun
2012-02-01
The usual Landau level quantization, as demonstrated in the 2D quantum Hall effect, is crucially based on the planar structure. In this talk, we explore its 3D counterpart possessing the full 3D rotational symmetry as well as the time reversal symmetry. We construct the Landau level Hamiltonians in 3 and higher dimensional flat space for both relativistic and non-relativistic fermions. The 3D cases with integer fillings are Z2 topological insulators. The non-relativistic version describes spin-1/2 fermions coupling to the Aharonov-Casher SU(2) gauge field. This system exhibits flat Landau levels in which the orbital angular momentum and the spin are coupled with a fixed helicity. Each filled Landau level contributes one 2D helical Dirac Fermi surface at an open boundary, which demonstrates the Z2 topological nature. A natural generalization to Dirac fermions is found as a square root problem of the above non-relativistic version, which can also be viewed as the Dirac equation defined on the phase space. All these Landau level problems can be generalized to arbitrary high dimensions systematically. [4pt] [1] Yi Li and Congjun Wu, arXiv:1103.5422.[0pt] [2] Yi Li, Ken Intriligator, Yue Yu and Congjun Wu, arXiv:1108.5650.
Fermion field renormalization prescriptions
Zhou, Yong
2005-01-01
We discuss all possible fermion field renormalization prescriptions in conventional field renormalization meaning and mainly pay attention to the imaginary part of unstable fermion Field Renormalization Constants (FRC). We find that introducing the off-diagonal fermion FRC leads to the decay widths of physical processes $t\\to c Z$ and $b\\to s \\gamma$ gauge-parameter dependent. We also discuss the necessity of renormalizing the bare fields in conventional quantum field theory.
Light Fermion Finite Mass Effects in Non-relativistic Bound States
Eiras, D; Eiras, Dolors; Soto, Joan
2000-01-01
We present analytic expressions for the vacuum polarization effects due to a light fermion with finite mass in the binding energy and in the wave function at the origin of QED and (weak coupling) QCD non-relativistic bound states. Applications to exotic atoms, \\Upsilon (1s) and t\\bar{t} production near threshold are briefly discussed.
Non-relativistic Quantum Mechanics versus Quantum Field Theories
Pineda, Antonio
2007-01-01
We briefly review the derivation of a non-relativistic quantum mechanics description of a weakly bound non-relativistic system from the underlying quantum field theory. We highlight the main techniques used.
Kanazawa, Takuya; Yamamoto, Arata
2016-01-01
We apply QCD-inspired techniques to study nonrelativistic N -component degenerate fermions with attractive interactions. By analyzing the singular-value spectrum of the fermion matrix in the Lagrangian, we derive several exact relations that characterize spontaneous symmetry breaking U (1 )×SU (N )→Sp (N ) through bifermion condensates. These are nonrelativistic analogues of the Banks-Casher relation and the Smilga-Stern relation in QCD. Nonlocal order parameters are also introduced and their spectral representations are derived, from which a nontrivial constraint on the phase diagram is obtained. The effective theory of soft collective excitations is derived, and its equivalence to random matrix theory is demonstrated in the ɛ regime. We numerically confirm the above analytical predictions in Monte Carlo simulations.
Nonrelativistic effective field theory for axions
Braaten, Eric; Mohapatra, Abhishek; Zhang, Hong
2016-10-01
Axions can be described by a relativistic field theory with a real scalar field ϕ whose self-interaction potential is a periodic function of ϕ . Low-energy axions, such as those produced in the early Universe by the vacuum misalignment mechanism, can be described more simply by a nonrelativistic effective field theory with a complex scalar field ψ whose effective potential is a function of ψ*ψ . We determine the coefficients in the expansion of the effective potential to fifth order in ψ*ψ by matching low-energy axion scattering amplitudes. In order to describe a Bose-Einstein condensate of axions that is too dense to truncate the expansion of the effective potential in powers of ψ*ψ , we develop a sequence of systematically improvable approximations to the effective potential that resum terms of all orders in ψ*ψ .
Nonrelativistic Effective Field Theory for Axions
Braaten, Eric; Zhang, Hong
2016-01-01
Axions can be described by a relativistic field theory with a real scalar field $\\phi$ whose self-interaction potential is a periodic function of $\\phi$. Low-energy axions, such as those produced in the early universe by the vacuum misalignment mechanism, can be described more simply by a nonrelativistic effective field theory with a complex scalar field $\\psi$ whose effective potential is a function of $\\psi^*\\psi$. We determine the coefficients in the expansion of the effective potential to fifth order in $\\psi^*\\psi$ by matching low-energy axion scattering amplitudes. In order to describe a Bose-Einstein condensate of axions that is too dense to expand the effective potential in powers of $\\psi^*\\psi$, we develop a sequence of systematically improvable approximations to the effective potential that include terms of all orders in $\\psi^*\\psi$.
Gravity duals for nonrelativistic conformal field theories.
Balasubramanian, Koushik; McGreevy, John
2008-08-08
We attempt to generalize the anti-de Sitter/conformal field theory correspondence to nonrelativistic conformal field theories which are invariant under Galilean transformations. Such systems govern ultracold atoms at unitarity, nucleon scattering in some channels, and, more generally, a family of universality classes of quantum critical behavior. We construct a family of metrics which realize these symmetries as isometries. They are solutions of gravity with a negative cosmological constant coupled to pressureless dust. We discuss realizations of the dust, which include a bulk superconductor. We develop the holographic dictionary and find two-point correlators of the correct form. A strange aspect of the correspondence is that the bulk geometry has two extra noncompact dimensions.
Mean field theory for fermion-based U(2) anyons
McGraw, P
1996-01-01
The energy density is computed for a U(2) Chern-Simons theory coupled to a non-relativistic fermion field (a theory of ``non-Abelian anyons'') under the assumptions of uniform charge and matter density. When the matter field is a spinless fermion, we find that this energy is independent of the two Chern-Simons coupling constants and is minimized when the non-Abelian charge density is zero. This suggests that there is no spontaneous breaking of the SU(2) subgroup of the symmetry, at least in this mean-field approximation. For spin-1/2 fermions, we find self-consistent mean-field states with a small non-Abelian charge density, which vanishes as the theory of free fermions is approached.
Entanglement and mutual information in 2d nonrelativistic field theories
Hosseini, Seyed Morteza
2015-01-01
We carry out a systematic study of entanglement entropy in nonrelativistic conformal field theories via holographic techniques. After a discussion of recent results concerning Galilean conformal field theories, we deduce a novel expression for the entanglement entropy of (1+1)-dimensional Lifshitz field theories --- this is done both at zero and finite temperature. Based on these results, we pose a conjecture for the anomaly coefficient of a Lifshitz field theory dual to new massive gravity. It is found that the Lifshitz entanglement entropy at finite temperature displays a striking similarity with that corresponding to a flat space cosmology in three dimensions. We claim that this structure is an inherent feature of the entanglement entropy for nonrelativistic conformal field theories. We finish by exploring the behavior of the mutual information for such theories.
Tomographic probability representation for quantum fermion fields
Andreev, V A; Man'ko, V I; Son, Nguyen Hung; Thanh, Nguyen Cong; Timofeev, Yu P; Zakharov, S D
2009-01-01
Tomographic probability representation is introduced for fermion fields. The states of the fermions are mapped onto probability distribution of discrete random variables (spin projections). The operators acting on the fermion states are described by fermionic tomographic symbols. The product of the operators acting on the fermion states is mapped onto star-product of the fermionic symbols. The kernel of the star-product is obtained. The antisymmetry of the fermion states is formulated as the specific symmetry property of the tomographic joint probability distribution associated with the states.
Quantum electrodynamics in finite volume and nonrelativistic effective field theories
Fodor, Z; Katz, S D; Lellouch, L; Portelli, A; Szabo, K K; Toth, B C
2015-01-01
Electromagnetic effects are increasingly being accounted for in lattice quantum chromodynamics computations. Because of their long-range nature, they lead to large finite-size effects over which it is important to gain analytical control. Nonrelativistic effective field theories provide an efficient tool to describe these effects. Here we argue that some care has to be taken when applying these methods to quantum electrodynamics in a finite volume.
Quantum electrodynamics in finite volume and nonrelativistic effective field theories
Energy Technology Data Exchange (ETDEWEB)
Fodor, Z. [Department of Physics, University of Wuppertal, D-42119 Wuppertal (Germany); Jülich Supercomputing Centre, Forschungszentrum Jülich, D-52428 Jülich (Germany); Institute for Theoretical Physics, Eötvös University, H-1117 Budapest (Hungary); Hoelbling, C. [Department of Physics, University of Wuppertal, D-42119 Wuppertal (Germany); Katz, S.D. [Institute for Theoretical Physics, Eötvös University, H-1117 Budapest (Hungary); MTA-ELTE Lendület Lattice Gauge Theory Research Group, H-1117 Budapest (Hungary); Lellouch, L., E-mail: lellouch@cpt.univ-mrs.fr [CNRS, Aix-Marseille U., U. de Toulon, CPT, UMR 7332, F-13288, Marseille (France); Portelli, A. [School of Physics & Astronomy, University of Southampton, SO17 1BJ (United Kingdom); Szabo, K.K. [Department of Physics, University of Wuppertal, D-42119 Wuppertal (Germany); Jülich Supercomputing Centre, Forschungszentrum Jülich, D-52428 Jülich (Germany); Toth, B.C. [Department of Physics, University of Wuppertal, D-42119 Wuppertal (Germany)
2016-04-10
Electromagnetic effects are increasingly being accounted for in lattice quantum chromodynamics computations. Because of their long-range nature, they lead to large finite-size effects over which it is important to gain analytical control. Nonrelativistic effective field theories provide an efficient tool to describe these effects. Here we argue that some care has to be taken when applying these methods to quantum electrodynamics in a finite volume.
Quantum electrodynamics in finite volume and nonrelativistic effective field theories
Directory of Open Access Journals (Sweden)
Z. Fodor
2016-04-01
Full Text Available Electromagnetic effects are increasingly being accounted for in lattice quantum chromodynamics computations. Because of their long-range nature, they lead to large finite-size effects over which it is important to gain analytical control. Nonrelativistic effective field theories provide an efficient tool to describe these effects. Here we argue that some care has to be taken when applying these methods to quantum electrodynamics in a finite volume.
Janiszewski, Stefan; Karch, Andreas
2013-02-22
We argue that generic nonrelativistic quantum field theories with a holographic description are dual to Hořava gravity. We construct explicit examples of this duality embedded in string theory by starting with relativistic dual pairs and taking a nonrelativistic scaling limit.
Generalized Gravitational Entropy from Fermion Fields
Huang, Wung-Hong
2016-01-01
The generalized gravitational entropy proposed in recent by Lewkowycz and Maldacena [1] is extended to the system of Fermion fields. We first find the regular wave solution of Fermion field which has arbitrary frequency and mode number on the BTZ spacetime, and then use it to calculate the exact gravitational entropy. The results show that there is a threshold frequency below which the Fermion fields could not contribute the generalized gravitational entropy. Also, the static and zero-mode solutions have not entropy, contrast to that in scalar field. We also found that the entropy of the static scalar fields and non-static fermions is an increasing function of mode number and, after arriving the maximum entropy it becomes a deceasing function and is derived to the asymptotic value.
Fields and fluids on curved non-relativistic spacetimes
Geracie, Michael; Roberts, Matthew M
2015-01-01
We consider non-relativistic curved geometries and argue that the background structure should be generalized from that considered in previous works. In this approach the derivative operator is defined by a Galilean spin connection valued in the Lie algebra of the Galilean group. This includes the usual spin connection plus an additional "boost connection" which parameterizes the freedom in the derivative operator not fixed by torsion or metric compatibility. As an example of this approach we develop the theory of non-relativistic dissipative fluids and find significant differences in both equations of motion and allowed transport coefficients from those found previously. Our approach also immediately generalizes to systems with independent mass and charge currents as would arise in multicomponent fluids. Along the way we also discuss how to write general locally Galilean invariant non-relativistic actions for multiple particle species at any order in derivatives. A detailed review of the geometry and its rela...
The entanglement spectrum and R\\'enyi entropies of non-relativistic conformal fermions
Porter, William J
2016-01-01
We characterize non-perturbatively the R\\'enyi entropies of degree n=2,3,4, and 5 of three-dimensional, strongly coupled many-fermion systems in the scale-invariant regime of short interaction range and large scattering length, i.e. in the unitary limit. We carry out our calculations using lattice methods devised recently by us. Our results show the effect of strong pairing correlations on the entanglement entropy, which modify the sub-leading behavior for large subsystem sizes (as characterized by the dimensionless parameter x=kF L_A, where kF is the Fermi momentum and L_A the linear subsystem size), but leave the leading order unchanged relative to the non-interacting case. Moreover, we find that the onset of the sub-leading asymptotic regime is at surprisingly small x=2-4. We provide further insight into the entanglement properties of this system by analyzing the spectrum of the entanglement Hamiltonian of the two-body problem from weak to strong coupling. The low-lying entanglement spectrum displays clear...
Cosmic expansion from boson and fermion fields
Energy Technology Data Exchange (ETDEWEB)
De Souza, Rudinei C; Kremer, Gilberto M, E-mail: rudijantsch@gmail.com, E-mail: kremer@fisica.ufpr.br [Departamento de Fisica, Universidade Federal do Parana, Curitiba (Brazil)
2011-06-21
This paper consists in analyzing an action that describes boson and fermion fields minimally coupled to the gravity and a common matter field. The self-interaction potentials of the fields are not chosen a priori but from the Noether symmetry approach. The Noether forms of the potentials allow the boson field to play the role of dark energy and matter and the fermion field to behave as standard matter. The constant of motion and the cyclic variable associated with the Noether symmetry allow the complete integration of the field equations, whose solution produces a universe with alternated periods of accelerated and decelerated expansion.
Cosmic expansion from boson and fermion fields
de Souza, Rudinei C
2011-01-01
This paper consists in analyzing an action that describes boson and fermion fields minimally coupled to the gravity and a common matter field. The self-interaction potentials of the fields are not chosen a priori but from the Noether symmetry approach. The Noether forms of the potentials allow the boson field to play the role of dark energy and matter and the fermion field to behave as standard matter. The constant of motion and the cyclic variable associated with the Noether symmetry allow the complete integration of the field equations, whose solution produces a Universe with alternated periods of accelerated and decelerated expansion.
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
Nonrelativistic mean-field description of the deformation of Λ hypernuclei
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The deformations of light Λ hypernuclei are studied in an extended nonrelativistic deformed Skyrme-Hartree-Fock approach with realistic modern nucleonic Skyrme forces,pairing correlations,and a microscopical lambda-nucleon interaction derived from Brueckner-Hartree-Fock calculations.Compared to the large effect of an additional Λ particle on nuclear deformation in the light soft nuclei within relativistic mean field method,this effect is much smaller in the nonrelativistic mean-field approximation.
Amplified Fermion Production from Overpopulated Bose Fields
Berges, J; Sexty, D
2014-01-01
We study the real-time dynamics of fermions coupled to scalar fields in a linear sigma model, which is often employed in the context of preheating after inflation or as a low-energy effective model for quantum chromodynamics. We find a dramatic amplification of fermion production in the presence of highly occupied bosonic quanta for weak as well as strong couplings. For this we consider the range of validity of different methods: lattice simulations with male/female fermions, the mode functions approach and the quantum 2PI effective action with its associated kinetic theory. For strongly coupled fermions we find a rapid approach to a Fermi-Dirac distribution with time-dependent temperature and chemical potential parameters, while the bosons are still far from equilibrium.
Vall, A N; Leviant, V M; Naumov, D V; Sinitskaya, A V
2001-01-01
In a nonrelativistic contact four-fermion model we show that simple regularization prescriptions together with a definite fine-tuning of the cut-off parameter dependence of 'bare' quantities give the exact solutions for the two-particle sector and Goldstone modes. Their correspondence with the self-adjoint extension into Pontryagin space is established leading to self-adjoint semi-bounded Hamiltonians in three-particle sectors as well. Renormalized Faddeev equations for the bound states with Fredholm properties are obtained and analyzed. (author)
Noether symmetry for non-minimally coupled fermion fields
de Souza, Rudinei C
2008-01-01
A cosmological model where a fermion field is non-minimally coupled with the gravitational field is studied. By applying Noether symmetry the possible functions for the potential density of the fermion field and for the coupling are determined. Cosmological solutions are found showing that the non-minimally coupled fermion field behaves as an inflaton describing an accelerated inflationary scenario, whereas the minimally coupled fermion field describes a decelerated period being identified as dark matter.
Bethe ansatz matrix elements as non-relativistic limits of form factors of quantum field theory
Kormos, M.; Mussardo, G.; Pozsgay, B.
2010-01-01
We show that the matrix elements of integrable models computed by the algebraic Bethe ansatz (BA) can be put in direct correspondence with the form factors of integrable relativistic field theories. This happens when the S-matrix of a Bethe ansatz model can be regarded as a suitable non-relativistic
Nonrelativistic Geodesic Motion
Mangiarotti, L
1999-01-01
We show that any second order dynamic equation on a configuration space $X\\to R$ of nonrelativistic mechanics can be seen as a geodesic equation with respect to some (nonlinear) connection on the tangent bundle $TX\\to X$ of relativistic velocities. We compare relativistic and nonrelativistic geodesic equations, and study the Jacobi vector fields along nonrelativistic geodesics.
Coulomb's law corrections and fermion field localization in a tachyonic de Sitter thick braneworld
Cartas-Fuentevilla, Roberto; Escalante, Alberto; Germán, Gabriel; Herrera-Aguilar, Alfredo; Rigel Mora-Luna, Refugio
2016-05-01
Following recent studies which show that it is possible to localize gravity as well as scalar and gauge vector fields in a tachyonic de Sitter thick braneworld, we investigate the solution of the gauge hierarchy problem, the localization of fermion fields in this model, the recovering of the Coulomb law on the non-relativistic limit of the Yukawa interaction between bulk fermions and gauge bosons localized in the brane, and confront the predicted 5D corrections to the photon mass with its upper experimental/observational bounds, finding the model physically viable since it passes these tests. In order to achieve the latter aims we first consider the Yukawa interaction term between the fermionic and the tachyonic scalar fields MF(T)ΨΨ̅ in the action and analyze four distinct tachyonic functions F(T) that lead to four different structures of the respective fermionic mass spectra with different physics. In particular, localization of the massless left-chiral fermion zero mode is possible for three of these cases. We further analyze the phenomenology of these Yukawa interactions among fermion fields and gauge bosons localized on the brane and obtain the crucial and necessary information to compute the corrections to Coulomb's law coming from massive KK vector modes in the non-relativistic limit. These corrections are exponentially suppressed due to the presence of the mass gap in the mass spectrum of the bulk gauge vector field. From our results we conclude that corrections to Coulomb's law in the thin brane limit have the same form (up to a numerical factor) as far as the left-chiral massless fermion field is localized on the brane. Finally we compute the corrections to the Coulomb's law for an arbitrarily thick brane scenario which can be interpreted as 5D corrections to the photon mass. By performing consistent estimations with brane phenomenology, we found that the predicted corrections to the photon mass, which are well bounded by the experimentally observed or
Coulomb’s law corrections and fermion field localization in a tachyonic de Sitter thick braneworld
Energy Technology Data Exchange (ETDEWEB)
Cartas-Fuentevilla, Roberto; Escalante, Alberto [Instituto de Física, Benemérita Universidad Autónoma de Puebla,Apdo. postal J-48, 72570 Puebla, Pue. (Mexico); Germán, Gabriel [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México,Apdo. Postal 48-3, 62251 Cuernavaca, Morelos (Mexico); Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road,Oxford, OX1 3NP (United Kingdom); Herrera-Aguilar, Alfredo [Instituto de Física, Benemérita Universidad Autónoma de Puebla,Apdo. postal J-48, 72570 Puebla, Pue. (Mexico); Institutode Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo,Edificio C-3, Ciudad Universitaria, CP 58040, Morelia, Michoacán (Mexico); Mora-Luna, Refugio Rigel [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México,Apdo. Postal 48-3, 62251 Cuernavaca, Morelos (Mexico)
2016-05-11
Following recent studies which show that it is possible to localize gravity as well as scalar and gauge vector fields in a tachyonic de Sitter thick braneworld, we investigate the solution of the gauge hierarchy problem, the localization of fermion fields in this model, the recovering of the Coulomb law on the non-relativistic limit of the Yukawa interaction between bulk fermions and gauge bosons localized in the brane, and confront the predicted 5D corrections to the photon mass with its upper experimental/observational bounds, finding the model physically viable since it passes these tests. In order to achieve the latter aims we first consider the Yukawa interaction term between the fermionic and the tachyonic scalar fields MF(T)ΨΨ-bar in the action and analyze four distinct tachyonic functions F(T) that lead to four different structures of the respective fermionic mass spectra with different physics. In particular, localization of the massless left-chiral fermion zero mode is possible for three of these cases. We further analyze the phenomenology of these Yukawa interactions among fermion fields and gauge bosons localized on the brane and obtain the crucial and necessary information to compute the corrections to Coulomb’s law coming from massive KK vector modes in the non-relativistic limit. These corrections are exponentially suppressed due to the presence of the mass gap in the mass spectrum of the bulk gauge vector field. From our results we conclude that corrections to Coulomb’s law in the thin brane limit have the same form (up to a numerical factor) as far as the left-chiral massless fermion field is localized on the brane. Finally we compute the corrections to the Coulomb’s law for an arbitrarily thick brane scenario which can be interpreted as 5D corrections to the photon mass. By performing consistent estimations with brane phenomenology, we found that the predicted corrections to the photon mass, which are well bounded by the experimentally
Bound states of massive fermions in Aharonov-Bohm-like fields
Energy Technology Data Exchange (ETDEWEB)
Khalilov, V.R. [Moscow State University, Faculty of Physics, Moscow (Russian Federation)
2014-01-15
Bound states of massive fermions in Aharonov-Bohm (AB)-like fields have analytically been studied. The Hamiltonians with the (AB)-like potentials are essentially singular and therefore require specification of a one-parameter self-adjoint extension. We construct self-adjoint Dirac Hamiltonians with the AB potential in 2+1 dimensions that are specified by boundary conditions at the origin. It is of interest that for some range of the extension parameter the AB potential can bind relativistic charged massive fermions. The bound-state energy is determined by the AB magnetic flux and depends upon the fermion spin and extension parameter; it is a periodical function of the magnetic flux. We also construct self-adjoint Hamiltonians for the so-called Aharonov-Casher (AC) problem, show that nonrelativistic neutral massive fermions can be bound by the (AC) background, determine the range of the extension parameter in which fermion bound states exist, and find their energies as well as wave functions. (orig.)
Non-relativistic Limit of Dirac Equations in Gravitational Field and Quantum Effects of Gravity
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Based on unified theory of electromagnetic interactions and gravitational interactions, the non-relativistic limit of the equation of motion of a charged Dirac particle in gravitational field is studied. From the Schrodinger equation obtained from this non-relativistic limit, we can see that the classical Newtonian gravitational potential appears as a part of the potential in the Schrodinger equation, which can explain the gravitational phase effects found in COW experiments.And because of this Newtonian gravitational potential, a quantum particle in the earth's gravitational field may form a gravitationally bound quantized state, which has already been detected in experiments. Three different kinds of phase effects related to gravitational interactions are studied in this paper, and these phase effects should be observable in some astrophysical processes. Besides, there exists direct coupling between gravitomagnetic field and quantum spin, and radiation caused by this coupling can be used to directly determine the gravitomagnetic field on the surface of a star.
Energy Technology Data Exchange (ETDEWEB)
Cannoni, Mirco [Universidad de Huelva, Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Huelva (Spain)
2016-03-15
We find an exact formula for the thermally averaged cross section times the relative velocity left angle σv{sub rel} right angle with relativistic Maxwell-Boltzmann statistics. The formula is valid in the effective field theory approach when the masses of the annihilation products can be neglected compared with the dark matter mass and cut-off scale. The expansion at x = m/T >> 1 directly gives the nonrelativistic limit of left angle σv{sub rel} right angle, which is usually used to compute the relic abundance for heavy particles that decouple when they are nonrelativistic. We compare this expansion with the one obtained by expanding the total cross section σ(s) in powers of the nonrelativistic relative velocity vr. We show the correct invariant procedure that gives the nonrelativistic average left angle σv{sub rel} right angle {sub nr} coinciding with the large x expansion of left angle σv{sub rel} right angle in the comoving frame. We explicitly formulate flux, cross section, thermal average, collision integral of the Boltzmann equation in an invariant way using the true relativistic relative v{sub rel}, showing the uselessness of the Moeller velocity and further elucidating the conceptual and numerical inconsistencies related with its use. (orig.)
Cannoni, Mirco
2015-01-01
We find an exact formula for the thermally averaged cross section times the relative velocity $\\langle \\sigma v_{\\text{rel}} \\rangle$ with relativistic Maxwell-Boltzmann statistics. The formula is valid in the effective field theory approach when the masses of the annihilation products can be neglected compared with the dark matter mass and cut-off scale. The expansion at $x=m/T\\gg 1$ directly gives the nonrelativistic limit of $\\langle \\sigma v_{\\text{rel}}\\rangle$ which is usually used to compute the relic abundance for heavy particles that decouple when they are nonrelativistic. We compare this expansion with the one obtained by expanding the total cross section $\\sigma(s)$ in powers of the nonrelativistic relative velocity $v_r$. We show the correct invariant procedure that gives the nonrelativistic average $\\langle \\sigma_{nr} v_r \\rangle_{nr}$ coinciding with the large $x$ expansion of $\\langle \\sigma v_{\\text{rel}}\\rangle$ in the comoving frame. We explicitly formulate flux, cross section, thermal aver...
Holographic fermions in external magnetic fields
Gubankova, E; Cubrovic, M; Schalm, K; Schijven, P; Zaanen, J
2011-01-01
We study the Fermi level structure of 2+1-dimensional strongly interacting electron systems in external magnetic field using the AdS/CFT correspondence. The gravity dual of a finite density fermion system is a Dirac field in the background of the dyonic AdS-Reissner-Nordstrom black hole. In the probe limit the magnetic system can be reduced to the non-magnetic one, with Landau-quantized momenta and rescaled thermodynamical variables. We find that at strong enough magnetic fields, the Fermi surface vanishes and the quasiparticle is lost either through a crossover to conformal regime or through a phase transition to an unstable Fermi surface. In the latter case, the vanishing Fermi velocity at the critical magnetic field triggers the non-Fermi liquid regime with unstable quasiparticles and a change in transport properties of the system. We associate it with a metal-"strange metal" phase transition. Next we compute compute the DC Hall and longitudinal conductivities using the gravity-dressed fermion propagators....
Estimates on Functional Integrals of Quantum Mechanics and Non-relativistic Quantum Field Theory
Bley, Gonzalo A.; Thomas, Lawrence E.
2017-01-01
We provide a unified method for obtaining upper bounds for certain functional integrals appearing in quantum mechanics and non-relativistic quantum field theory, functionals of the form {E[{exp}(A_T)]} , the (effective) action {A_T} being a function of particle trajectories up to time T. The estimates in turn yield rigorous lower bounds for ground state energies, via the Feynman-Kac formula. The upper bounds are obtained by writing the action for these functional integrals in terms of stochastic integrals. The method is illustrated in familiar quantum mechanical settings: for the hydrogen atom, for a Schrödinger operator with {1/|x|^2} potential with small coupling, and, with a modest adaptation of the method, for the harmonic oscillator. We then present our principal applications of the method, in the settings of non-relativistic quantum field theories for particles moving in a quantized Bose field, including the optical polaron and Nelson models.
Localization of massive and massless fermion on two field brane
Farokhtabar, A
2016-01-01
In this paper we study fermion localization and resonances on a special type of braneworld model supporting brane splitting. In such models one can construct multi-wall branes which cause considerable simplification in field equations. We use a polynomial superpotential to construct this brane. The suitable Yukawa coupling between the background scalar field and localized fermion is determined. The massive fermion resonance spectrum is obtained. The number of resonances is increased for higher values of Yukawa coupling.
Bose-Einstein Condensation of Relativistic Fermions in a Magnetic Field
Feng, Bo; Ren, Hai-cang; Wu, Ping-ping
2015-01-01
The Bose-Einstein condensation of bound pairs made of equally and oppositely charged fermions in a magnetic field is investigated using a relativistic model.The Gaussian fluctuations have been taken into account in order to study the spectrum of bound pairs in the strong coupling region. We found, in weak coupling reagion, the condensation temperature increases with an increasing magnetic field displaying the magnetic catalysis effect. In strong coupling region, the inverse magnetic catalysis appears when the magnetic field is low and is replaced by the usual magnetic catalysis effect when magnetic field is sufficiently high, in contrast to the nonrelativistic case where the inverse magnetic catalysis prevails in strong coupling region regardless of the strength of the magnetic field. The resulting response to the magnetic field is the consequence of the competition between the dimensional reduction by Landau orbitals in pairing dynamics and the anisotropy of the kinetic spectrum of the bound pairs. We thus c...
Fermion field as inflaton, dark energy and dark matter
Grams, Guilherme; Kremer, Gilberto M
2014-01-01
The search for constituents that can explain the periods of accelerating expansion of the Universe is a fundamental topic in cosmology. In this context, we investigate how fermionic fields minimally and non-minimally coupled with the gravitational field may be responsible for accelerated regimes during the evolution of the Universe. The forms of the potential and coupling of the model are determined through the technique of the Noether symmetry for two cases. The first case comprises a Universe filled only with the fermion field. Cosmological solutions are straightforwardly obtained for this case and an exponential inflation mediated by the fermion field is possible with a non-minimal coupling. The second case takes account of the contributions of radiation and baryonic matter in the presence of the fermion field. In this case the fermion field plays the role of dark energy and dark matter, and when a non-minimal coupling is allowed, it mediates a power-law inflation.
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.
Fermionic ghosts in Moyal string field theory
Bars, Itzhak; Kishimoto, Isao; Matsuo, Yutaka
2003-07-01
We complete the construction of the Moyal star formulation of bosonic open string field theory (MSFT) by providing a detailed study of the fermionic ghost sector. In particular, as in the case of the matter sector, (1) we construct a map from Witten's star product to the Moyal product, (2) we propose a regularization scheme which is consistent with the matter sector and (3) as a check of the formalism, we derive the ghost Neumann coefficients algebraically directly from the Moyal product. The latter satisfy the Gross-Jevicki nonlinear relations even in the presence of the regulator, and when the regulator is removed they coincide numerically with the expression derived from conformal field theory. After this basic construction, we derive a regularized action of string field theory in the Siegel gauge and define the Feynman rules. We give explicitly the analytic expression of the off-shell four point function for tachyons, including the ghost contribution. Some of the results in this paper have already been used in our previous publications. This paper provides the technical details of the computations which were omitted there.
Fermionic Ghosts in Moyal String Field Theory
Bars, Itzhak; Matsuo, Y
2003-01-01
We complete the construction of the Moyal star formulation of bosonic open string field theory (MSFT) by providing a detailed study of the fermionic ghost sector. In particular, as in the case of the matter sector, (1) we construct a map from Witten's star product to the Moyal product, (2) we propose a regularization scheme which is consistent with the matter sector and (3) as a check of the formalism, we derive the ghost Neumann coefficients algebraically directly from the Moyal product. The latter satisfy the Gross-Jevicki nonlinear relations even in the presence of the regulator, and when the regulator is removed they coincide numerically with the expression derived from conformal field theory. After this basic construction, we derive a regularized action of string field theory in the Siegel gauge and define the Feynman rules. We give explicitly the analytic expression of the off-shell four point function for tachyons, including the ghost contribution. Some of the results in this paper have already been us...
Operator Product Expansion and Conservation Laws in Non-Relativistic Conformal Field Theories
Golkar, Siavash
2014-01-01
We explore the consequences of conformal symmetry for the operator product expansions in nonrelativistic field theories. Similar to the relativistic case, the OPE coefficients of descendants are related to that of the primary. However, unlike relativistic CFTs the 3-point function of primaries is not completely specified by conformal symmetry. Here, we show that the 3-point function between operators with nonzero particle number, where (at least) one operator has the lowest dimension allowed by unitarity, is determined up to a numerical coefficient. We also look at the structure of the family tree of primaries with zero particle number and discuss the presence of conservation laws in this sector.
A gauge field theory of fermionic continuous-spin particles
Directory of Open Access Journals (Sweden)
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.
Velocity operator and velocity field for spinning particles in (non-relativistic) quantum mechanics
Energy Technology Data Exchange (ETDEWEB)
Recami, E. [Bergamo Univ. (Italy). Facolta` di Ingegneria]|[INFN, Milan (Italy)]|[Campinas State Univ., SP (Brazil). Dept. of Applied Math.; Salesi, G. [Catania Univ. (Italy). Dip. di Fisica
1995-06-01
Starting from the formal expressions of the hydrodynamical (or local) quantities employed in the applications of Clifford Algebras to quantum mechanics, the paper introduces - in terms of the ordinary tensorial framework - a new definition for the field of a generic quantity. By translating from Clifford into tensor algebra, a new (non-relativistic) velocity operator for a spin 1/2 particle is also proposed. This operator is the sum of the ordinary part p/m describing the mean motion (the motion of the center-of-mass), and of a second part associated with the so-called Zitterbewegung, which is the spin internal motion observed in the center-of- mass frame. This spin component of the velocity operator is non-zero not only in the Pauli theoretical framework, i.e. in presence of external magnetic fields and spin precession, but also in the Schroedinger case, when the wave-function is a spin eigenstate. In the latter case, one gets a decomposition of the velocity field for the Madelueng fluid into two distinct parts: which the constitutes the non-relativistic analogue of the Gordon decomposition for the Dirac current.
Energy Technology Data Exchange (ETDEWEB)
Goncalves, Bruno; Dias Junior, Mario Marcio [Instituto Federal de Educacacao, Ciencia e Tecnologia Sudeste de Minas Gerais, Juiz de Fora, MG (Brazil)
2013-07-01
Full text: The discussion of experimental manifestations of torsion at low energies is mainly related to the torsion-spin interaction. In this respect the behavior of Dirac field and the spinning particle in an external torsion field deserves and received very special attention. In this work, we consider the combined action of torsion and magnetic field on the massive spinor field. In this case, the Dirac equation is not straightforward solved. We suppose that the spinor has two components. The equations have mixed terms between the two components. The electromagnetic field is introduced in the action by the usual gauge transformation. The torsion field is described by the field S{sub μ}. The main purpose of the work is to get an explicit form to the equation of motion that shows the possible interactions between the external fields and the spinor in a Hamiltonian that is independent to each component. We consider that S{sub 0} is constant and is the unique non-vanishing term of S{sub μ}. This simplification is taken just to simplify the algebra, as our main point is not to describe the torsion field itself. In order to get physical analysis of the problem, we consider the non-relativistic approximation. The final result is a Hamiltonian that describes a half spin field in the presence of electromagnetic and torsion external fields. (author)
On the Infrared Problem for the Dressed Non-Relativistic Electron in a Magnetic Field
Amour, Laurent; Grebert, Benoit; Guillot, Jean-Claude
2008-01-01
We consider a non-relativistic electron interacting with a classical magnetic field pointing along the $x_3$-axis and with a quantized electromagnetic field. The system is translation invariant in the $x_3$-direction and we consider the reduced Hamiltonian $H(P_3)$ associated with the total momentum $P_3$ along the $x_3$-axis. For a fixed momentum $P_3$ sufficiently small, we prove that $H(P_3)$ has a ground state in the Fock representation if and only if $E'(P_3)=0$, where $P_3 \\mapsto E'(P_3)$ is the derivative of the map $P_3 \\mapsto E(P_3) = \\inf \\sigma (H(P_3))$. If $E'(P_3) \
Energy modulation of nonrelativistic electrons in an optical near field on a metal microslit
Ishikawa, R.; Bae, J.; Mizuno, K.
2001-04-01
Energy modulation of nonrelativistic electrons with a laser beam using a metal microslit as an interaction circuit has been investigated. An optical near field is induced in the proximity of the microslit by illumination of the laser beam. The electrons passing close to the slit are accelerated or decelerated by an evanescent wave contained in the near field whose phase velocity is equal to the velocity of the electrons. The electron-evanescent wave interaction in the microslit has been analyzed theoretically and experimentally. The theory has predicted that electron energy can be modulated at optical frequencies. Experiments performed in the infrared region have verified theoretical predictions. The electron-energy changes of more than ±5 eV with a 10 kW CO2 laser pulse at the wavelength of 10.6 μm has been successfully observed for an electron beam with an energy of less than 80 keV.
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.
Caprioli, Damiano
2014-01-01
We use large hybrid (kinetic ions-fluid electrons) simulations to study ion acceleration and generation of magnetic turbulence due to the streaming of energetic particles that are self-consistently accelerated at non-relativistic shocks. When acceleration is efficient (at quasi-parallel shocks), we find that the magnetic field develops transverse components and is significantly amplified in the pre-shock medium. The total amplification factor is larger than 10 for shocks with Mach number $M=100$, and scales with the square root of $M$. We find that in the shock precursor the energy spectral density of excited magnetic turbulence is proportional to spectral energy distribution of accelerated particles at corresponding resonant momenta, in good agreement with the predictions of quasilinear theory of diffusive shock acceleration. We discuss the role of Bell's instability, which is predicted and found to grow faster than resonant instability in shocks with $M\\gtrsim 30$. Ahead of these strong shocks we distinguis...
Virial Theorem for Non-relativistic Quantum Fields in D Spatial Dimensions
Lin, Chris L
2015-01-01
The virial theorem for non-relativistic complex fields in $D$ spatial dimensions and with arbitrary many-body potential is derived, using path-integral methods and scaling arguments recently developed to analyze quantum anomalies in lower-dimensional systems. The potential appearance of a Jacobian $J$ due to a change of variables in the path-integral expression for the partition function of the system is pointed out, although in order to make contact with the literature most of the analysis deals with the $J=1$ case. The virial theorem is recast into a form that displays the effect of microscopic scales on the thermodynamics of the system. From the point of view of this paper the case usually considered, $J=1$, is not natural, and the generalization to the case $J\
Vortex dynamics in nonrelativistic Abelian Higgs model
Directory of Open Access Journals (Sweden)
A.A. Kozhevnikov
2015-11-01
Full Text Available The dynamics of the gauge vortex with arbitrary form of a contour is considered in the framework of the nonrelativistic Abelian Higgs model, including the possibility of the gauge field interaction with the fermion asymmetric background. The equations for the time derivatives of the curvature and the torsion of the vortex contour generalizing the Betchov–Da Rios equations in hydrodynamics, are obtained. They are applied to study the conservation of helicity of the gauge field forming the vortex, twist, and writhe numbers of the vortex contour. It is shown that the conservation of helicity is broken when both terms in the equation of the vortex motion are present, the first due to the exchange of excitations of the phase and modulus of the scalar field and the second one due to the coupling of the gauge field forming the vortex, with the fermion asymmetric background.
Towards state locality in quantum field theory: free fermions
Oeckl, Robert
2013-01-01
We provide a restricted solution to the state locality problem in quantum field theory for the case of free fermions. Concretely, we present a functorial quantization scheme that takes as input a classical free fermionic field theory. Crucially, no data is needed beyond the classical structures evident from a Lagrangian setting. The output is a quantum field theory encoded in a weakened version of the positive formalism of the general boundary formulation. When the classical data is augmented with complex structures on hypersurfaces, the quantum data correspondingly augment to the full positive formalism and the standard quantization of free fermionic field theory is recovered. This augmentation can be performed selectively, i.e., it may be limited to a subcollection of hypersurfaces. The state locality problem arises from the fact that suitable complex structures only exist on a very restricted class of unbounded hypersurfaces. But standard quantization requires them on all hypersurfaces and is thus only abl...
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.
Dynamics of perturbations in Double Field Theory & non-relativistic string theory
Energy Technology Data Exchange (ETDEWEB)
Ko, Sung Moon [Department of Physics, Sogang University,Seoul 121-742 (Korea, Republic of); Melby-Thompson, Charles M. [Kavli Institute for the Physics and Mathematics of the Universe (WPI),The University of Tokyo Institutes for Advanced Study (UTIAS), The University of Tokyo,Kashiwanoha, Kashiwa, 277-8583 (Japan); Department of Physics, Fudan University,220 Handan Road, 200433 Shanghai (China); Meyer, René [Kavli Institute for the Physics and Mathematics of the Universe (WPI),The University of Tokyo Institutes for Advanced Study (UTIAS), The University of Tokyo,Kashiwanoha, Kashiwa, 277-8583 (Japan); Park, Jeong-Hyuck [Department of Physics, Sogang University,Seoul 121-742 (Korea, Republic of)
2015-12-22
Double Field Theory provides a geometric framework capable of describing string theory backgrounds that cannot be understood purely in terms of Riemannian geometry — not only globally (‘non-geometry’), but even locally (‘non-Riemannian’). In this work, we show that the non-relativistic closed string theory of Gomis and Ooguri http://dx.doi.org/10.1063/1.1372697 arises precisely as such a non-Riemannian string background, and that the Gomis-Ooguri sigma model is equivalent to the Double Field Theory sigma model of http://dx.doi.org/10.1016/j.nuclphysb.2014.01.003 on this background. We further show that the target-space formulation of Double Field Theory on this non-Riemannian background correctly reproduces the appropriate sector of the Gomis-Ooguri string spectrum. To do this, we develop a general semi-covariant formalism describing perturbations in Double Field Theory. We derive compact expressions for the linearized equations of motion around a generic on-shell background, and construct the corresponding fluctuation Lagrangian in terms of novel completely covariant second order differential operators. We also present a new non-Riemannian solution featuring Schrödinger conformal symmetry.
Fermion localization and resonances on two-field thick branes
Almeida, C A S; Gomes, A R; Casana, R
2009-01-01
We consider $(4,1)$-dimensional branes constructed with two scalar fields $\\phi$ and $\\chi$ coupled to a Dirac spinor field by means of a general Yukawa coupling. The equation of motion for the coefficients of the chiral decomposition of the spinor in curved spacetime leads to a Sch\\"odinger-like equation whose solutions allow to obtain the masses of the fermionic modes. The simplest Yukawa coupling $\\bar\\Psi\\phi\\chi\\Psi$ is considered for the Bloch brane model and fermion localization is studied. We found resonances for both chiralities and related their appearance to branes with internal structure.
Fermion localization and resonances on two-field thick branes
Almeida, C. A. S.; Casana, R.; Ferreira, M. M., Jr.; Gomes, A. R.
2009-06-01
We consider (4, 1)-dimensional branes constructed with two scalar fields ϕ and χ coupled to a Dirac spinor field by means of a general Yukawa coupling. The equation of motion for the coefficients of the chiral decomposition of the spinor in curved spacetime leads to a Schrödinger-like equation whose solutions allow to obtain the masses of the fermionic modes. The simplest Yukawa coupling Ψ¯ϕχΨ is considered for the Bloch brane model and fermion localization is studied. We found resonances for both chiralities and related their appearance to branes with internal structure.
Cosmological model with non-minimally coupled fermionic field
Ribas, M O; Kremer, G M
2007-01-01
A model for the Universe is proposed whose constituents are: (a) a dark energy field modeled by a fermionic field non-minimally coupled with the gravitational field, (b) a matter field which consists of pressureless baryonic and dark matter fields and (c) a field which represents the radiation and the neutrinos. The coupled system of Dirac's equations and Einstein field equations is solved numerically by considering a spatially flat homogeneous and isotropic Universe. It is shown that the proposed model can reproduce the expected red-shift behaviors of the deceleration parameter, of the density parameters of each constituent and of the luminosity distance. Furthermore, for small values of the red-shift the constant which couples the fermionic and gravitational fields has a remarkable influence on the density and deceleration parameters.
Fermionic Sum Representations for Conformal Field Theory Characters
Kedem, R; McCoy, B M; Melzer, E
1993-01-01
We present sum representations for all characters of the unitary Virasoro minimal models. They can be viewed as fermionic companions of the Rocha-Caridi sum representations, the latter related to the (bosonic) Feigin-Fuchs-Felder construction. We also give fermionic representations for certain characters of the general $(G^{(1)})_k \\times (G^{(1)})_l \\over (G^{(1)})_{k+l}}$ coset conformal field theories, the non-unitary minimal models ${\\cal M}(p,p+2)$ and ${\\cal M}(p,kp+1)$, the $N$=2 superconformal series, and the $\\ZZ_N$-parafermion theories, and relate the $q\\to 1$ behaviour of all these fermionic sum representations to the thermodynamic Bethe Ansatz.
Trapping Dirac fermions in tubes generated by two scalar fields
Casana, R.; Gomes, A. R.; Martins, G. V.; Simas, F. C.
2014-04-01
In this work we consider (1,1)-dimensional resonant Dirac fermionic states on tubelike topological defects. The defects are formed by rings in (2,1) dimensions, constructed with two scalar fields ϕ and χ, and embedded in the (3,1)-dimensional Minkowski spacetime. The tubelike defects are attained from a Lagrangian density explicitly dependent with the radial distance r relative to the ring axis and the radius and thickness of its cross section are related to the energy density. For our purposes we analyze a general Yukawa-like coupling between the topological defect and the fermionic field ηF(ϕ ,χ)ψ¯ψ. With a convenient decomposition of the fermionic fields in left and right components, we establish a coupled set of first-order differential equations for the amplitudes of the left and right components of the Dirac field. After decoupling and decomposing the amplitudes in polar coordinates, the radial modes satisfy Schrödinger-like equations whose eigenvalues are the masses of the fermionic states. With F(ϕ ,χ)=ϕχ the Schrödinger-like equations are numerically solved with appropriated boundary conditions. Several resonance peaks for both components are obtained, and the results are confronted with the qualitative analysis of the Schrödinger-like potentials.
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
Fermionic Particle Production by Varying Electric and Magnetic Fields
Sogut, Kenan; Yanar, Hilmi; Havare, Ali
2016-11-01
Creation of fermionic particles by a time-dependent electric field and a space-dependent magnetic field is studied with the Bogoulibov transformation method. Exact analytic solutions of the Dirac equation are obtained in terms of the Whittaker functions and the particle creation number density depending on the electric and magnetic fields is determined. Supported by the Research Fund of Mersin University in TURKEY with project number: 2016-1-AP4-1425
Spacetime Variation of Lorentz-Violation Coefficients at Nonrelativistic Scale
Lane, Charles D
2016-01-01
The notion of uniform and/or constant tensor fields of rank $>0$ is incompatible with general curved spacetimes. This work considers the consequences of certain tensor-valued coefficients for Lorentz violation in the Standard-Model Extension varying with spacetime position. We focus on two of the coefficients, $a_\\mu$ and $b_\\mu$, that characterize Lorentz violation in massive fermions, particularly in those fermions that constitute ordinary matter. We calculate the nonrelativistic hamiltonian describing these effects, and use it to extract the sensitivity of several precision experiments to coefficient variation.
Gravity as a Higgs field; 2, fermion-gravitation complex
Sardanashvily, G
1994-01-01
Gravitation theory meets spontaneous symmetry breaking when the structure group of the principal linear frame bundle LX over a world manifold X^4 is reducible to the Lorentz group SO(3,1). The physical underlying reason of this reduction is Dirac fermion matter possessing only exact Lorentz symmetries. The associated Higgs field is a tetrad gravitational field h represented by a section of the quotient \\Si of LX by SO(3,1). The feature of gravity as a Higgs field issues from the fact that, in the presence of different tetrad fields, there are nonequivalent representations of cotangent vectors to X^4 by Dirac's matrices. It follows that fermion fields must be regarded only in a pair with a certain tetrad field. These pairs constitute the so-called fermion-gravitation complex and are represented by sections of the composite spinor bundle S\\to\\Si\\to X^4 where values of tetrad gravitational fields play the role of coordinate parameters, besides familiar world coordinates. In Part I of the work [gr-qc:9405013], ge...
More On Nonrelativistic Diffeomorphism Invariance
Andreev, Oleg
2014-01-01
Certain aspects of nonrelativistic diffeomorphisms in 2+1 dimensions are investigated. These include a nonrelativistic limit of some relativistic actions in 3 dimensions, the Seiberg-Witten map, a modification of the viscosity tensor in particular due to a non-uniform magnetic field, a redefinition of background fields, and 1/R terms on Riemann surfaces of constant curvature.
Trapping Dirac fermions in tubes generated by two scalar fields
Casana, R; Martins, G V; Simas, F C
2013-01-01
In this work we consider $(1,1)-$dimensional resonant Dirac fermionic states on tube-like topological defects. The defects are formed by rings in $(2,1)$ dimensions, constructed with two scalar field $\\phi$ and $\\chi$, and embedded in the $(3,1)-$dimensional Minkowski spacetime. The tube-like defects are attained from a lagrangian density explicitly dependent with the radial distance $r$ relative to the ring axis and the radius and thickness of the its cross-section are related to the energy density. For our purposes we analyze a general Yukawa-like coupling between the topological defect and the fermionic field $\\eta F(\\phi,\\chi)\\bar\\psi\\psi$. With a convenient decomposition of the fermionic fields in left- and right- chiralities, we establish a coupled set of first order differential equations for the amplitudes of the left- and right- components of the Dirac field. After decoupling and decomposing the amplitudes in polar coordinates, the radial modes satisfy Schr\\"odinger-like equations whose eigenvalues a...
Massive Dirac fermions and the zero field quantum Hall effect
Raya, Alfredo
2008-01-01
Through an explicit calculation for a Lagrangian in quantum electrodynamics in (2+1)-space--time dimensions (QED$_3$), making use of the relativistic Kubo formula, we demonstrate that the filling factor accompanying the quantized electrical conductivity for massive Dirac fermions of a single species in two spatial dimensions is a half (in natural units) when time reversal and parity symmetries of the Lagrangian are explicitly broken by the fermion mass term. We then discuss the most general form of the QED$_3$ Lagrangian, both for irreducible and reducible representations of the Dirac matrices in the plane, with emphasis on the appearance of a Chern-Simons term. We also identify the value of the filling factor with a zero field quantum Hall effect (QHE).
Massive Dirac fermions and the zero field quantum Hall effect
Raya, Alfredo; Reyes, Edward D.
2008-09-01
Through an explicit calculation for a Lagrangian in quantum electrodynamics in (2+1)-spacetime dimensions (QED3), making use of the relativistic Kubo formula, we demonstrate that the filling factor accompanying the quantized electrical conductivity for massive Dirac fermions of a single species in two spatial dimensions is a half (in natural units) when time reversal and parity symmetries of the Lagrangian are explicitly broken by the fermion mass term. We then discuss the most general form of the QED3 Lagrangian, for both irreducible and reducible representations of the Dirac matrices in the plane, with emphasis on the appearance of a Chern-Simons term. We also identify the value of the filling factor with a zero field quantum Hall effect (QHE).
Quantum Algorithms for Fermionic Quantum Field Theories
2014-04-28
construction that gives quasi- linear asymptotic scaling in time and the number of lattice sites, as in the bosonic case. In contrast with bosonic field...components, γ µ is a two-dimensional representation of the Dirac algebra , and ψ̄ = ψ†γ0.1 We use the Majorana representation, namely, γ0 = [ 0 −i i 0...Hilbert spaces and can therefore be efficiently decomposed into elementary gates for any constant number of particle species, N , via the Solovay
Exotic Non-relativistic String
Casalbuoni, Roberto; Longhi, Giorgio
2007-01-01
We construct a classical non-relativistic string model in 3+1 dimensions. The model contains a spurion tensor field that is responsible for the non-commutative structure of the model. Under double dimensional reduction the model reduces to the exotic non-relativistic particle in 2+1 dimensions.
Thermodynamics of Relativistic Fermions with Chern-Simons Coupling
Bralic, N; Schaposnik, F A
1994-01-01
We study the thermodynamics of the relativistic Quantum Field Theory of massive fermions in three space-time dimensions coupled to an Abelian Maxwell-Chern-Simons gauge field. We evaluate the specific heat at finite temperature and density and find that the variation with the statistical angle is consistent with the non-relativistic ideas on generalized statistics.
Mean Field Evolution of Fermions with Coulomb Interaction
Porta, Marcello; Rademacher, Simone; Saffirio, Chiara; Schlein, Benjamin
2017-03-01
We study the many body Schrödinger evolution of weakly coupled fermions interacting through a Coulomb potential. We are interested in a joint mean field and semiclassical scaling, that emerges naturally for initially confined particles. For initial data describing approximate Slater determinants, we prove convergence of the many-body evolution towards Hartree-Fock dynamics. Our result holds under a condition on the solution of the Hartree-Fock equation, that we can only show in a very special situation (translation invariant data, whose Hartree-Fock evolution is trivial), but that we expect to hold more generally.
Dispersion relation of excitation mode in strongly interacting fermions matter
Institute of Scientific and Technical Information of China (English)
Wang Yan-Ping; Chen Ji-Sheng
2008-01-01
This paper analyses the dispersion relation of the excitation mode in non-relativistic interacting fermion matter.The polarization tensor is calculated with the random phase approximation in terms of finite temperature field theory.With the polarization tensor, the influences of temperature, particle number density and interaction strength on the dispersion relation are discussed in detail. It finds that the collective effects are qualitatively more important in the unitary fermions than those in the finite contact interaction matter.
Localization and quasilocalization of a spin-1 /2 fermion field on a two-field thick braneworld
Guo, Heng; Xie, Qun-Ying; Fu, Chun-E.
2015-11-01
Localization of a spin-1 /2 fermion on the braneworld is an important and interesting problem. It is well known that a five-dimensional free massless fermion Ψ minimally coupled to gravity cannot be localized on the Randall-Sundrum braneworld. In order to trap such a fermion, the coupling between the fermion and bulk scalar fields should be introduced. In this paper, localization and quasilocalization of a bulk fermion on the thick braneworld generated by two scalar fields (a kink scalar ϕ and a dilaton scalar π ) are investigated. Two types of couplings between the fermion and two scalars are considered. One coupling is the usual Yukawa coupling -η Ψ ¯ϕ Ψ between the fermion and kink scalar, another one is λ Ψ ¯ΓM∂Mπ γ5Ψ between the fermion and dilaton scalar. The left-chiral fermion zero mode can be localized on the brane, and both the left- and right-chiral fermion massive Kaluza-Klein modes may be localized or quasilocalized. Hence the four-dimensional massless left-chiral fermion and massive Dirac fermions, whose lifetime is infinite or finite, can be obtained on the brane.
The fermion bag approach to lattice field theories
Chandrasekharan, Shailesh
2009-01-01
We propose a new approach to the fermion sign problem in systems where there is a coupling $U$ such that when it is infinite the fermions are paired into bosons and there is no fermion permutation sign to worry about. We argue that as $U$ becomes finite fermions are liberated but are naturally confined to regions which we refer to as {\\em fermion bags}. The fermion sign problem is then confined to these bags and may be solved using the determinantal trick. In the parameter regime where the fermion bags are small and their typical size does not grow with the system size, construction of Monte Carlo methods that are far more efficient than conventional algorithms should be possible. In the region where the fermion bags grow with system size, the fermion bag approach continues to provide an alternative approach to the problem but may lose its main advantage in terms of efficiency. The fermion bag approach also provides new insights and solutions to sign problems. A natural solution to the "silver blaze problem" ...
Surprises with Nonrelativistic Naturalness
Horava, Petr
2016-01-01
We explore the landscape of technical naturalness for nonrelativistic systems, finding surprises which challenge and enrich our relativistic intuition already in the simplest case of a single scalar field. While the immediate applications are expected in condensed matter and perhaps in cosmology, the study is motivated by the leading puzzles of fundamental physics involving gravity: The cosmological constant problem and the Higgs mass hierarchy problem.
The Anomalous Nambu-Goldstone Theorem in Relativistic/Nonrelativistic Quantum Field Theory
Ohsaku, Tadafumi
2013-01-01
The anomalous Nambu-Goldstone (NG) theorem which is found as a violation of counting law of the number of NG bosons of the normal NG theorem in nonrelativistic and Lorentz-symmetry-violated relativistic theories is studied in detail, with emphasis on its mathematical aspect from Lie algebras, geometry to number theory. The basis of counting law of NG bosons in the anomalous NG theorem is examined by Lie algebras (local) and Lie groups (global). A quasi-Heisenberg algebra is found generically in various symmetry breaking schema of the anomalous NG theorem, and it indicates that it causes a violation/modification of the Heisenberg uncertainty relation in an NG sector which can be experimentally confirmed. The formalism of effective potential is presented for understanding the mechanism of anomalous NG theorem with the aid of our result of Lie algebras. After an investigation on a bosonic kaon condensation model with a finite chemical potential as an explicit Lorentz-symmetry-breaking parameter, a model Lagrangi...
Tunneling for Dirac Fermions in Constant Magnetic Field
Choubabi, El Bouazzaoui; Jellal, Ahmed
2009-01-01
The tunneling effect of two-dimensional Dirac fermions in a constant magnetic field is studied. This can be done by using the continuity equation at some points to determine the corresponding reflexion and transmission coefficients. For this, we consider a system made of graphene as superposition of two different regions where the second is characterized by an energy gap t'. In fact, we treat concrete systems to practically give two illustrations: barrier and diode. For each case, we discuss the transmission in terms of the ratio of the energy conservation and t'. Moreover, we analyze the resonant tunneling by introducing a scalar Lorentz potential where it is shown that a total transmission is possible.
Slave-Fermion Mean-Field Theory of Heisenberg Model
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
A nearly half-filled two-dimensional Heisenberg model is investigated. A slave-fermion method with fermions as the charge carriers and bosons as the spin carriers is proposed. The ground state shows antiferromagnetic long range order at T = 0. The spin-spin correlation and static susceptibility are also obtained.
Fermion localization on asymmetric two-field thick branes
Energy Technology Data Exchange (ETDEWEB)
Zhao Zhenhua; Liu Yuxiao; Li Haitao, E-mail: zhaozhh09@lzu.c, E-mail: liuyx@lzu.edu.c, E-mail: liht07@lzu.c [Institute of Theoretical Physics, Lanzhou University, Lanzhou 730000 (China)
2010-09-21
In this paper we investigate the localization of fermions on asymmetric thick branes generated by two scalars {phi} and {chi}. In order to trap fermions on the asymmetric branes with kink-like warp factors, the couplings with the background scalars {eta}{Psi}-barF({chi},{phi}){Psi} are introduced, where F({chi}, {phi}) is a function of {phi} and {chi}. We find that the coupling {eta}{Psi}-bar{sub {chi}{phi}{Psi}} does not support the localization of four-dimensional fermions on the branes. While, for the case {eta}{Psi}-bar{sub {chi}{Psi}} +{eta}'{Psi}-bar{sub {phi}{Psi}} , which is the kink-fermion coupling corresponding to one-scalar-generated brane scenarios, the zero mode of left-handed fermions could be trapped on the branes under some conditions.
A non-relativistic logarithmic conformal field theory from a holographic point of view
Bergshoeff, Eric A.; de Haan, Sjoerd; Merbis, Wout; Rosseel, Jan
2011-01-01
We study a fourth-order derivative scalar field configuration in a fixed Lifshitz background. Using an auxiliary field we rewrite the equations of motion as two coupled second order equations. We specialize to the limit that the mass of the scalar field degenerates with that of the auxiliary field a
Teleparallel dark energy model with a fermionic field via Noether symmetry
Energy Technology Data Exchange (ETDEWEB)
Kucukakca, Yusuf [Akdeniz University, Department of Physics, Faculty of Science, Antalya (Turkey)
2014-10-15
In the present work, we consider a model with a fermionic field that is non-minimally coupled to gravity in the framework of teleparallel gravity. In order to determine the forms of the coupling and potential function of fermionic field for the considered model, we use the Noether symmetry approach. By applying this approach, for the Friedman-Robertson-Walker metric, we obtain the respective potential and coupling functions as a linear and power-law form of the bilinear Ψ. Furthermore, we search for the exact cosmological solution of the model. It is shown that the fermionic field plays the role of dark energy. (orig.)
Fermion Density Induced Instability of the W-Boson Pair Condensate in Strong Magnetic Field
Poppitz, E R
1993-01-01
The electroweak vacuum structure in an external magnetic field close to the lower critical value is considered at finite fermion density. It is shown that the leading effect of the fermions is to reduce the symmetry of the W-pair condensate in the direction of the magnetic field. The energy is minimized by the appearance of a helicoidal structure of the condensate along the magnetic field.
Effective field theories for QCD with rooted staggered fermions
Bernard, Claude; Shamir, Yigal
2007-01-01
Even highly improved variants of lattice QCD with staggered fermions show significant violations of taste symmetry at currently accessible lattice spacings. In addition, the "rooting trick" is used in order to simulate with the correct number of light sea quarks, and this makes the lattice theory nonlocal, even though there is good reason to believe that the continuum limit is in the correct universality class. In order to understand scaling violations, it is thus necessary to extend the construction of the Symanzik effective theory to include rooted staggered fermions. We show how this can be done, starting from a generalization of the renormalization-group approach to rooted staggered fermions recently developed by one of us. We then explain how the chiral effective theory follows from the Symanzik action, and show that it leads to "rooted" staggered chiral perturbation theory as the correct chiral theory for QCD with rooted staggered fermions. We thus establish a direct link between the renormalization-gro...
Spin Topological Field Theory and Fermionic Matrix Product States
Kapustin, Anton; You, Minyoung
2016-01-01
We study state-sum constructions of G-equivariant spin-TQFTs and their relationship to Matrix Product States. We show that in the Neveu-Schwarz, Ramond, and twisted sectors, the states of the theory are generalized Matrix Product States. We apply our results to revisit the classification of fermionic Short-Range-Entangled phases with a unitary symmetry G. Interesting subtleties appear when the total symmetry group is a nontrivial extension of G by fermion parity.
Energy Technology Data Exchange (ETDEWEB)
Becar, Ramon [Universidad Catolica de Temuco, Departamento de Ciencias Matematicas y Fisicas, Temuco (Chile); Gonzalez, P.A. [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Saavedra, Joel [Pontificia Universidad Catolica de Valparaiso, Instituto de Fisica, Valparaiso (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica, Facultad de Ciencias, La Serena (Chile)
2015-02-01
We study massive charged fermionic perturbations in the background of a charged two-dimensional dilatonic black hole, and we solve the Dirac equation analytically. Then we compute the reflection and transmission coefficients and the absorption cross section for massive charged fermionic fields, and we show that the absorption cross section vanishes at the low- and high-frequency limits. However, there is a range of frequencies where the absorption cross section is not null. Furthermore, we study the effect of the mass and electric charge of the fermionic field over the absorption cross section. (orig.)
1998-01-01
We systematically study the exclusion statistics for quasi-particles for Conformal Field Theory spectra by employing a method based on recursion relations for truncated spectra. Our examples include generalized fermions in c
Green-Function-Based Monte Carlo Method for Classical Fields Coupled to Fermions
Weiße, Alexander
2009-01-01
Microscopic models of classical degrees of freedom coupled to non-interacting fermions occur in many different contexts. Prominent examples from solid state physics are descriptions of colossal magnetoresistance manganites and diluted magnetic semiconductors, or auxiliary field methods for correlated electron systems. Monte Carlo simulations are vital for an understanding of such systems, but notorious for requiring the solution of the fermion problem with each change in the classical field c...
Chiral extension of lattice field theory with Ginsparg-Wilson fermions
Lim, Kyung-Taek
In 1994, Brower, Shen and Tan proposed "chirally extended QCD" (or XQCD), and current research extends this method to incorporate fermions obeying Ginsparg-Wilson relation, e.g. Overlap fermion. The hope in this research is that the XQCD can overcome the difficulty in standard lattice approach associated with small quark mass by adding explicit fields while maintaining chiral symmetry on the lattice, and that the XQCD has desired continuum limit. I show that the 4-d Yukawa Overlap XQCD fermion action can be derived from the standard 5-d domain-wall action. I also present study on the imaginary part of the determinant of the coset XQCD Dirac operator.
Charged Lifshitz black hole and probed Lorentz-violation fermions from holography
Luo, Cheng-Jian; Kuang, Xiao-Mei; Shu, Fu-Wen
2017-06-01
We analytically obtain a new charged Lifshitz solution by adding a non-relativistic Maxwell field in Hořava-Lifshitz gravity. The black hole exhibits an anisotropic scaling between space and time (Lifshitz scaling) in the UV limit, while in the IR limit, the Lorentz invariance is approximately recovered. We introduce the probed Lorentz-violation fermions into the background and holographically investigate the spectral properties of the dual fermionic operator. The Lorentz-violation of the fermions will enhance the peak and correspond larger fermi momentum, which compensates the non-relativistic bulk effect of the dynamical exponent (z). For a fixed z, when the Lorentz-violation of fermions increases to a critical value, the behavior of the low energy excitation goes from a non-Fermi liquid type to a Fermi liquid type, which implies a kind of phase transition.
Charged Lifshitz black hole and probed Lorentz-violation fermions from holography
Directory of Open Access Journals (Sweden)
Cheng-Jian Luo
2017-06-01
Full Text Available We analytically obtain a new charged Lifshitz solution by adding a non-relativistic Maxwell field in Hořava–Lifshitz gravity. The black hole exhibits an anisotropic scaling between space and time (Lifshitz scaling in the UV limit, while in the IR limit, the Lorentz invariance is approximately recovered. We introduce the probed Lorentz-violation fermions into the background and holographically investigate the spectral properties of the dual fermionic operator. The Lorentz-violation of the fermions will enhance the peak and correspond larger fermi momentum, which compensates the non-relativistic bulk effect of the dynamical exponent (z. For a fixed z, when the Lorentz-violation of fermions increases to a critical value, the behavior of the low energy excitation goes from a non-Fermi liquid type to a Fermi liquid type, which implies a kind of phase transition.
Coulomb's law corrections and fermion field localization in a tachyonic de Sitter thick braneworld
Cartas-Fuentevilla, R; Germán, Gabriel; Herrera-Aguilar, Alfredo; Mora-Luna, Refugio Rigel
2014-01-01
In this work, following recent studies which show that it is possible to localize gravity as well as scalar and gauge vector fields in a tachyonic de Sitter thick braneworld, we investigate the localization of fermion fields in this model. In order to achieve this aim we consider the Yukawa interaction term between the fermions and the tachyonic condensate scalar field MF(T)barPsiPsi in the action and analyze four different cases corresponding to distinct tachyonic functions F(T(w)). The only condition that this function must satisfy in order to yield 4D chiral fermions upon dimensional reduction is to be odd in the extra dimension w. These functions lead to a different structure of the respective fermionic mass spectrum. In particular, localization of the massless left-chiral fermion zero mode is possible for three of these cases. We further analyze the phenomenology of the Yukawa interaction among fermion fields and gauge bosons localized on the brane and obtain the crucial and necessary information to comp...
Fermion production in a magnetic field in a de Sitter Universe
Crucean, Cosmin
2016-01-01
The process of fermion production in the field of a magnetic dipole on a de Sitter expanding universe is analyzed. The amplitude and probability for production of massive fermions are obtained using the exact solution of the Dirac equation written in the momentum-helicity basis. We found that the most probable transitions are those that generate the fermion pair perpendicular to the direction of the magnetic field. The behavior of the probability is graphically studied for large/small values of the expansion factor, and a detailed analysis of the probability in terms of the angle between the momenta vectors of the particle and antiparticle is performed. The phenomenon of fermion production is significant only at large expansion which corresponds to the conditions from the early Universe. When the expansion factor vanishes we recover the Minkowski limit where this process is forbidden by the simultaneous energy-momentum conservation.
Cosmological model with fermion and tachyon fields interacting via Yukawa-type potential
Ribas, Marlos O.; Devecchi, Fernando P.; Kremer, Gilberto M.
2016-02-01
A model for the universe with tachyonic and fermionic fields interacting through a Yukawa-type potential is investigated. It is shown that the tachyonic field answers for the initial accelerated regime and for the subsequent decelerated regime so that it behaves as an inflaton at early times and as a matter field at intermediate times, while the fermionic field has the role of a dark energy constituent, since it leads to an accelerated regime at later times. The interaction between the fields via a Yukawa-type potential controls the duration of the decelerated era, since a stronger coupling makes a shorter decelerated period.
Cosmological model with fermion and tachyon fields interacting via Yukawa-type potential
Ribas, Marlos O; Kremer, Gilberto M
2016-01-01
A model for the universe with tachyonic and fermionic fields interacting through a Yukawa-type potential is investigated. It is shown that the tachyonic field answers for the initial accelerated regime and for the subsequent decelerated regime so that it behaves as an inflaton at early times and as a matter field at intermediate times, while the fermionic field has the role of a dark energy constituent, since it leads to an accelerated regime at later times. The interaction between the fields via a Yukawa-type potential controls the duration of the decelerated era, since a stronger coupling makes a shorter decelerated period.
Montero, M
2011-01-01
We provide a simple argument showing that, in the limit of infinite acceleration, the entanglement in a fermionic field bipartite system must be independent of the choice of Unruh modes. This implies that most tensor product structures used previously to compute field entanglement in relativistic quantum information cannot give rise to physical results.
Harder, T Mark
2016-01-01
It is shown how Fermionic material particles can emerge from a covariant formulation of the de Broglie-Bohm theory. Material particles are continuous fields, formed as the eigenvalue of the Schrodinger field operator, evaluated along a Bohmian trajectory. The motivation for this work is due to a theorem proved by Malament that states there cannot be a relativistic quantum mechanics of localizable particles.
Fermion Fields in BTZ Black Hole Space-Time and Entanglement Entropy
Directory of Open Access Journals (Sweden)
Dharm Veer Singh
2015-01-01
Full Text Available We study the entanglement entropy of fermion fields in BTZ black hole space-time and calculate prefactor of the leading and subleading terms and logarithmic divergence term of the entropy using the discretized model. The leading term is the standard Bekenstein-Hawking area law and subleading term corresponds to first quantum corrections in black hole entropy. We also investigate the corrections to entanglement entropy for massive fermion fields in BTZ space-time. The mass term does not affect the area law.
Influence of the Magnetic Field on the Fermion Scattering off Bubble and Kink Walls
Cea, P; Tedesco, L
2000-01-01
We investigate the scattering of fermions off domain walls at the electroweak phase transition in presence of a magnetic field. We consider both the bubble wall and the kink domain wall. We derive and solve the Dirac equation for fermions with momentum perpendicular to the walls, and compute the transmission and reflection coefficients. In the case of kink domain wall, we briefly discuss the zero mode solutions localized on the wall. The possibile role of the magnetic field for the electroweak baryogenesis is also discussed.
Composite Fermion Theory for the High Field Wigner Crystal State
Narevich, Romanas; Murthy, Ganpathy; Fertig, Herbert
2001-03-01
The low filling fraction Quantum Hall Effect is reexamined using the hamiltonian composite fermion theory developed by Shankar and Murthy(R. Shankar and G. Murthy, Phys. Rev. Lett. 79), 4437 (1997). We address the experiment by Jiang et. al.(H. W. Jiang et. al., Phys. Rev. B 44), 8107 (1991) where the insulating phase surrounding the ν=1/5 quantum liquid was observed and its activation energies (gaps) measured. Previous studies either found gaps that were off by few orders of magnitude (Hartree-Fock calculations of the electronic Wigner crystal(D. Yoshioka and H. Fukuyama, J. Phys. Soc. Japan 47), 394 (1979)) or were unable to calculate them because of the computational complexity (Monte-Carlo studies of the correlated crystal(H. Yi and H. A. Fertig, Phys. Rev. B 58), 4019 (1998)). We use the Hartree-Fock approximation for the periodic density state of composite fermions and find gaps that have a correct order of magnitude and reproduce the experimental dependence on the filling factor. We also report the results of the shear modulus calculation relevant for the collective pinning of the crystal.
Ribas, Marlos O
2009-01-01
In this work the accelerated-decelerated transition in a primordial Universe is investigated by using the dynamics of fermion fields within the context of Einstein-Cartan theory, where apart from the curvature the space-time is also described by a torsion field. The model analyzed here has only a fermion field as the source of the gravitational field. The term associated with the spin of the fermion field plays the role of the inflaton which contributes to an accelerated regime whereas the one related to the fermion mass behaves as a matter field and is the responsible for a decelerated regime. Hence, by taking into account the spin of a massive fermion field it is possible to characterize the transition from the accelerated to the decelerated periods of the primordial Universe.
Fermionic field perturbations of a three-dimensional Lifshitz black hole in conformal gravity
González, P. A.; Vásquez, Yerko; Villalobos, Ruth Noemí
2017-09-01
We study the propagation of massless fermionic fields in the background of a three-dimensional Lifshitz black hole, which is a solution of conformal gravity. The black-hole solution is characterized by a vanishing dynamical exponent. Then we compute analytically the quasinormal modes, the area spectrum, and the absorption cross section for fermionic fields. The analysis of the quasinormal modes shows that the fermionic perturbations are stable in this background. The area and entropy spectrum are evenly spaced. In the low frequency limit, it is observed that there is a range of values of the angular momentum of the mode that contributes to the absorption cross section, whereas it vanishes in the high frequency limit. In addition, by a suitable change of variables a gravitational soliton can also be obtained and the stability of the quasinormal modes are studied and ensured.
Institute of Scientific and Technical Information of China (English)
ZHANG Ying; WANG Qing
2008-01-01
@@ Gauge covariance for Green's functions of a gauge theory through a fermion propagator in the presence of arbitrary external gauge field is proven and a formalism of gauge and Lorentz covariant Schwinger-Dyson equation for the fermion propagator with external gauge field is built up within ladder approximation.
Small field Coleman-Weinberg inflation driven by a fermion condensate
Iso, Satoshi; Kohri, Kazunori; Shimada, Kengo
2015-02-01
We revisit the small-field Coleman-Weinberg inflation, which has the following two problems: First, the smallness of the slow roll parameter ɛ requires the inflation scale to be very low. Second, the spectral index ns≈1 +2 η tends to become smaller compared to the observed value. In this paper, we consider two possible effects on the dynamics of inflation: radiatively generated nonminimal coupling to gravity ξ ϕ2R and condensation of fermions coupled to the inflaton as ϕ ψ ¯ψ . We show that the fermion condensate can solve the above problems.
Comment on "Fermion production in a magnetic field in a de Sitter universe"
Nicolaevici, Nistor
2016-01-01
We point out that the transition probabilities used in a recent perturbative calculation of pair creation in an external magnetic field in the expanding de Sitter space with the $in$ and $out$ fermion states defined by the Bunch-Davies modes [C. Crucean et al., Phys. Rev. D 73 044019 (20016)] are gauge dependent quantities. We examine the gauge variations of these amplitudes assuming a decoupling of the interaction at infinite times, which allows to conclude that the source of the problem lies in the nonoscillatory behavior of the fermion current in the infinite future.
Polarized light propagating in a magnetic field as a probe of millicharged fermions
Energy Technology Data Exchange (ETDEWEB)
Gries, H. [Heidelberg Univ. (Germany). Inst. fuer Theoretische Physik; Jaeckel, J.; Ringwald, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2006-07-15
Possible extensions of the standard model of elementary particle physics suggest the existence of particles with small, unquantized electric charge. Photon initiated pair production of millicharged fermions in an external magnetic field would manifest itself as a vacuum magnetic dichroism. We show that laser polarization experiments searching for this effect yield, in the mass range below 0.1 eV, much stronger constraints on millicharged fermions than previously considered laboratory searches. Vacuum magnetic birefringence originating from virtual pair production gives a slightly better constraint for masses between 0.1 eV and a few eV. We comment on the possibility that the vacuum magnetic dichroism observed by PVLAS arises from pair production of such millicharged fermions rather than from single production of axion-like particles. Such a scenario can be confirmed or firmly excluded by a search for invisible decays of orthopositronium with a sensitivity of about 10{sup -9} in the corresponding branching fraction. (Orig.)
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.
Bound states for fermions in the gauge Aharonov-Bohm field
Energy Technology Data Exchange (ETDEWEB)
Voropaev, S.A.; Galtsov, D.V.; Spasov, D.A. (Dept. of Theoretical Physics, Moscow State Univ. (USSR))
1991-09-05
In this paper we discuss some interesting properties of the Aharonov-Bohm interaction for relativistic spin-one-half particles. We will show that the AB potential is powerful enough to create bound states. We will then discuss the wave function, spin-coefficients and the energy level for the bound states of the fermions in the gauge AB field. (orig.).
Analogy between rotation and density for Dirac fermions in a magnetic field
Chen, Hao-Lei; Huang, Xu-Guang; Mameda, Kazuya
2015-01-01
We analyse the energy spectra of Dirac fermions in the presence of rotation and magnetic field. We find that the Landau degeneracy is resolved by rotation. A drastic change in the energy dispersion relation leads to the "rotational magnetic inhibition" that is a novel phenomenon analogous to the inverse magnetic catalysis in a magnetic system at finite chemical potential.
Torsion gravity with non-minimally coupled fermionic field: some cosmological models
Vignolo, Stefano; Fabbri, Luca
2014-01-01
We investigate some cosmological models arising from a non-minimal coupling of a fermionic field to gravity in the geometrical setting of Einstein-Cartan-Sciama-Kibble gravity. The role played by the non-minimal coupling together with torsion in facing problems such as cosmological singularity, inflation and dark energy is discussed.
Fundamental fermion interactions via vector bosons of unified SU(2) x SU(4) gauge fields
Marsch, Eckart; Narita, Yasuhito
2016-02-01
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)⊗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 ±4/3 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.
Fermionic Fields with Mass Dimension One as Supersymmetric Extension of the O'Raifeartaigh Model
Wunderle, Kai E.
The objective of this thesis is to derive a supersymmetric Lagrangian for fermionic fields with mass dimension one and to discuss their coupling to the O'Raifeartaigh model which is the simplest model permitting supersymmetry breaking. In addition it will be shown that eigenspinors of the charge conjugation operator (ELKO) exhibit a different transformation behaviour under discrete symmetries than previously assumed. The calculations confirm that ELKO spinors are not eigenspinors of the parity operator and satisfy (CPT)2 = -- I which identifies them as representation of a nonstandard Wigner class. However, it is found that ELKO spinors transform symmetrically under parity instead of the previously assumed asymmetry. Furthermore, it is demonstrated that ELKO spinors transform asymmetrically under time reversal which is opposite to the previously reported symmetric behaviour. These changes affect the (anti)commutation relations that are satisfied by the operators acting on ELKO spinors. Therefore, ELKO spinors satisfy the same (anti)commutation relations as Dirac spinors, even though they belong to two different representations of the Lorentz group. Afterwards, a supersymmetric model for fermionic fields with mass dimension one based on a general superfield with one spinor index is formulated. It includes the systematic derivation of all associated chiral and anti-chiral superfields up to third order in covariant derivatives. Starting from these fundamental superfields a supersymmetric on-shell Lagrangian that contains a kinetic term for the fermionic fields with mass dimension one is constructed. This on-shell Lagrangian is subsequently used to derive the on-shell super-current and to successfully formulate a consistent second quantisation for the component fields. In addition, the Hamiltonian in position space that corresponds to the supersymmetric Lagrangian is calculated. As the Lagrangian is by construction supersymmetric and the second quantisation of the
Institute of Scientific and Technical Information of China (English)
YANG Jin; YU Wan-Lun; XIANG An-Ping
2006-01-01
We use Lewis-Riesenfeld invariant approach to treat the modified Jaynes-Cummings models involving any forms of nonlinearty of the bosonic field when strong boson-fermion couplings are nilpotent Grassmann valued. The general state functions, time evolution operator and the time-evolution expressions for both the bosonic number and the fermionic number are presented.
Bubnov, Andrey; Gubina, Nadezda; Zhukovsky, Vladimir
2016-05-01
We study vacuum polarization effects in the model of Dirac fermions with additional interaction of an anomalous magnetic moment with an external magnetic field and fermion interaction with an axial-vector condensate. The proper time method is used to calculate the one-loop vacuum corrections with consideration for different configurations of the characteristic parameters of these interactions.
Non-minimal Maxwell-Chern-Simons theory and the composite Fermion model
Energy Technology Data Exchange (ETDEWEB)
Paschoal, Ricardo C. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Servico Nacional de Aprendizagem Industrial (SENAI), Rio de Janeiro, RJ (Brazil). Centro de Tecnologia da Industria Quimica e Textil (CETIQT); Helayel Neto, Jose A. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Grupo de Fisica Teorica Jose Leite Lopes, Petropolis, RJ (Brazil); E-mails: paschoal@cbpf.br; helayel@cbpf.br
2003-01-01
The magnetic field redefinition in Jain's composite fermion model for the fractional quantum Hall effect is shown to be effective described by a mean-field approximation of a model containing a Maxwell-Chern-Simons gauge field nominally coupled to matter. Also an explicit non-relativistic limit of the non-minimal (2+1) D Dirac's equation is derived. (author)
E$_{8(8)}$ Exceptional Field Theory: Geometry, Fermions and Supersymmetry
Baguet, Arnaud
2016-01-01
We present the supersymmetric extension of the recently constructed E$_{8(8)}$ exceptional field theory -- the manifestly U-duality covariant formulation of the untruncated ten- and eleven-dimensional supergravities. This theory is formulated on a (3+248) dimensional spacetime (modulo section constraint) in which the extended coordinates transform in the adjoint representation of E$_{8(8)}$. All bosonic fields are E$_{8(8)}$ tensors and transform under internal generalized diffeomorphisms. The fermions are tensors under the generalized Lorentz group SO(1,2)$\\times$SO(16), where SO(16) is the maximal compact subgroup of E$_{8(8)}$. Vanishing generalized torsion determines the corresponding spin connections to the extent they are required to formulate the field equations and supersymmetry transformation laws. We determine the supersymmetry transformations for all bosonic and fermionic fields such that they consistently close into generalized diffeomorphisms. In particular, the covariantly constrained gauge vect...
Boson-Fermion Duality in A2 Toda Field Theory
Institute of Scientific and Technical Information of China (English)
YANG Zhan-Ying; ZHAO Liu; SHI Kang-Jie
2002-01-01
In this paper, we consider a two-dimensional integrable and conformal invariant field theory with two Diracspinors and two scalar fields. This model has chiral symmetry and CP-like symmetry. Moreover, this model also has aNeother current depending only on the matter field. At last, we bosonize the spinor fields.
Energy Technology Data Exchange (ETDEWEB)
Dartora, C.A., E-mail: cadartora@eletrica.ufpr.b [Electrical Engineering Department, Federal University of Parana (UFPR) (Brazil); Cabrera, G.G., E-mail: cabrera@ifi.unicamp.b [Instituto de Fisica ' Gleb Wataghin' , Universidade Estadual de Campinas (UNICAMP), C.P. 6165, Campinas 13.083-970 SP (Brazil)
2010-05-31
The non-relativistic Pauli-Schroedinger theory has a richer gauge structure than usually expected, being invariant under the U(1)xSU(2) gauge group, which allows to define spin-current density vectors and obtains the relevant conserved quantities from Noether's theorem. The electromagnetic fields E and B play the role of the gauge potentials for the SU(2) sector of the gauge group and can possibly contribute with a corresponding invariant curvature self-energy term in the Lagrangian density. From the dynamics of the U(1) and SU(2) gauge fields we show that electric fields can be induced by spin-currents originated from the SU(2) gauge symmetry.
Aharonov-Bohm effect for a fermion field in the acoustic black hole background
Anacleto, M A; Mohammadi, A; Passos, E
2016-01-01
In this paper we consider the dynamics of a massive spinor field in the background of the acoustic black hole spacetime and then compute the differential cross section through the use of the partial wave approach. We show that an effect similar to the gravitational Aharonov-Bohm effect occurs for massive fermion fields moving in this effective metric. We discuss the limiting cases and compare the results with the bosonic case.
Mean field and collisional dynamics of interacting fermion-boson systems the Jaynes-Cummings model
Takano-Natti, E R
1996-01-01
A general time-dependent projection technique is applied to the study of the dynamics of quantum correlations in a system consisting of interacting fermionic and bosonic subsystems, described by the Jaynes-Cummings Hamiltonian. The amplitude modulation of the Rabi oscillations which occur for a strong, coherent initial bosonic field is obtained from the spin intrinsic depolarization resulting from collisional corrections to the mean-field approximation.
BRST approach to Lagrangian formulation for mixed-symmetry fermionic higher-spin fields
Moshin, P Yu
2007-01-01
We construct a Lagrangian description for irreducible half-integer higher-spin representations of the Poincare group with the corresponding Young tableaux having two rows, on a basis of the BRST approach. Starting with a formulation for fermionic higher-spin fields in a flat space of any dimension in terms of an auxiliary Fock space, we realize a conversion of the initial operator constraint system (constructed with respect to the relations extracting irreducible Poincare-group representations) into a first-class constraint system. For this purpose, we find auxiliary representations of the constraints subsuperalgebra containing the subsystem of second-class constraints in terms of Verma modules. We propose a universal procedure of constructing gauge-invariant Lagrangians with reducible gauge symmetries describing the dynamics of fermionic fields of any spin. No off-shell constraints for the fields and gauge parameters are used from the very beginning. It is shown that only the constraints corresponding to an ...
Entropy current for non-relativistic fluid
Banerjee, Nabamita; Jain, Akash; Roychowdhury, Dibakar
2014-01-01
We study transport properties of a parity-odd, non-relativistic charged fluid in presence of background electric and magnetic fields. To obtain stress tensor and charged current for the non-relativistic system we start with the most generic relativistic fluid, living in one higher dimension and reduce the constituent equations along the light-cone direction. We also reduce the equation satisfied by the entropy current of the relativistic theory and obtain a consistent entropy current for the non-relativistic system (we call it "canonical form" of the entropy current). Demanding that the non-relativistic fluid satisfies the second law of thermodynamics we impose constraints on various first order transport coefficients. For parity even fluid, this is straight forward; it tells us positive definiteness of different transport coefficients like viscosity, thermal conductivity, electric conductivity etc. However for parity-odd fluid, canonical form of the entropy current fails to confirm the second law of thermody...
BRST approach to Lagrangian formulation for mixed-symmetry fermionic higher-spin fields
Moshin, Pavel Yu.; Reshetnyak, Alexander A.
2007-10-01
We construct a Lagrangian description of irreducible half-integer higher-spin representations of the Poincare group with the corresponding Young tableaux having two rows, on a basis of the BRST approach. Starting with a description of fermionic higher-spin fields in a flat space of any dimension in terms of an auxiliary Fock space, we realize a conversion of the initial operator constraint system (constructed with respect to the relations extracting irreducible Poincare-group representations) into a first-class constraint system. For this purpose, we find auxiliary representations of the constraint subsuperalgebra containing the subsystem of second-class constraints in terms of Verma modules. We propose a universal procedure of constructing gauge-invariant Lagrangians with reducible gauge symmetries describing the dynamics of both massless and massive fermionic fields of any spin. No off-shell constraints for the fields and gauge parameters are used from the very beginning. It is shown that the space of BRST cohomologies with a vanishing ghost number is determined only by the constraints corresponding to an irreducible Poincare-group representation. To illustrate the general construction, we obtain a Lagrangian description of fermionic fields with generalized spin (3/2, 1/2) and (3/2, 3/2) on a flat background containing the complete set of auxiliary fields and gauge symmetries.
Thermal fermionic dispersion relations in a magnetic field
Elmfors, P; Skagerstam, B S; Elmfors, Per; Persson, David; Skagerstam, Bo Sture
1996-01-01
The thermal self-energy of an electron in a static uniform magnetic field B is calculated to first order in the fine structure constant \\alpha and to all orders in eB. We use two methods, one based on the Furry picture and another based on Schwinger's proper-time method. As external states we consider relativistic Landau levels with special emphasis on the lowest Landau level. In the high-temperature limit we derive self-consistent dispersion relations for particle and hole excitations, showing the chiral asymmetry caused by the external field. For weak fields, earlier results on the ground- state energy and the anomalous magnetic moment are discussed and compared with the present analysis. In the strong-field limit the appearance of a field-independent imaginary part of the self-energy, related to Landau damping in the e^{+}e^{-} plasma, is pointed out.
Vector and fermion fields on a bouncing brane with a decreasing warp factor in a string-like defect
Sousa, L J S; Dantas, D M; Almeida, C A S
2014-01-01
In a recent work, a model has been proposed where a brane is made of a scalar field with bounce-type configurations and embedded in a bulk with a string-like metric. This model produces an AdS scenario where the components of the energy momentum tensor are finite and have its positivity ensured by a suitable choice of the bounce configurations. In the present work, we study the issue of gauge and fermion field localization in this scenario. In contrast with the five dimensional case here the gauge field is localized without the dilaton contribution. Nevertheless, it is remarkable that the localization of the fermion field depends on the introduction of a minimal coupling with the angular component of the gauge field, which differs clearly from five dimensional scenarios. Furthermore, we perform a qualitative analysis of the fermionic massive modes and conclude that only left handed fermions could be localized in the brane.
Nataf, Pierre; Lajkó, Miklós; Wietek, Alexander; Penc, Karlo; Mila, Frédéric; Läuchli, Andreas M.
2016-10-01
We show that, in the presence of a π /2 artificial gauge field per plaquette, Mott insulating phases of ultracold fermions with SU (N ) symmetry and one particle per site generically possess an extended chiral phase with intrinsic topological order characterized by an approximate ground space of N low-lying singlets for periodic boundary conditions, and by chiral edge states described by the SU(N ) 1 Wess-Zumino-Novikov-Witten conformal field theory for open boundary conditions. This has been achieved by extensive exact diagonalizations for N between 3 and 9, and by a parton construction based on a set of N Gutzwiller projected fermionic wave functions with flux π /N per triangular plaquette. Experimental implications are briefly discussed.
Energy Technology Data Exchange (ETDEWEB)
Chimento, L P; Forte, M [Physics Department, UBA, 1428 Buenos Aires (Argentina); Devecchi, F P; Kremer, G M; Ribas, M O; Samojeden, L L, E-mail: kremer@fisica.ufpr.br, E-mail: devecchi@fisica.ufpr.br, E-mail: chimento@df.uba.ar [Physics Department, UFPR, 81531-990 Curitiba (Brazil)
2011-07-08
In this work we review if fermionic sources could be responsible for accelerated periods during the evolution of a FRW universe. In a first attempt, besides the fermionic source, a matter constituent would answer for the decelerated periods. The coupled differential equations that emerge from the field equations are integrated numerically. The self-interaction potential of the fermionic field is considered as a function of the scalar and pseudo-scalar invariants. It is shown that the fermionic field could behave like an inflaton field in the early universe, giving place to a transition to a matter dominated (decelerated) period. In a second formulation we turn our attention to analytical results, specifically using the idea of form-invariance transformations. These transformations can be used for obtaining accelerated cosmologies starting with conventional cosmological models. Here we reconsider the scalar field case and extend the discussion to fermionic fields. Finally we investigate the role of a Dirac field in a Brans-Dicke (BD) context. The results show that this source, in combination with the BD scalar, promote a final eternal accelerated era, after a matter dominated period.
Perturbative Expansion around the Gaussian Effective Potential of the Fermion Field Theory
Lee, G H; Yee, J H; Lee, Geon Hyoung; Lee, Tack Hwi; Yee, Jae Hyung
1998-01-01
We have extended the perturbative expansion method around the Gaussian effective action to the fermionic field theory, by taking the 2-dimensional Gross-Neveu model as an example. We have computed both the zero temperature and the finite temperature effective potentials of the Gross-Neveu model up to the first perturbative correction terms, and have found that the critical temperature, at which dynamically broken symmetry is restored, is significantly improved for small value of the flavour number.
Free massless fermionic fields of arbitrary spin in d-dimensional anti-de Sitter space
Energy Technology Data Exchange (ETDEWEB)
Vasiliev, M.A.
1988-04-25
Free massless fermionic fields of arbitrary spins, corresponding to fully symmetric tensor-spinor irreducible representations of the flat little group SO(d-2), are described in d-dimensional anti-de Sitter space in terms of differential forms. Appropriate linearized higher-spin curvature 2-forms are found. Explicitly gauge invariant higher-spin actions are constructed in terms of these linearized curvatures.
Gisin, Boris V
2012-01-01
Dirac's equation in the field of a circularly polarized electromagnetic wave and constant magnetic field has exact localized non-stationary solutions. The solutions corresponds relativistic fermions only. Among them singular solutions with energy eigenvalues close to each other are found. The solutions are most practicable and can be separated by means of the phase matching between the momentum of the electromagnetic wave and spinor. Characteristic parameters of the singular states are defined.
Finite pulse effects on fermion pair creation from strong electric fields
Taya, Hidetoshi; Fujii, Hirotsugu; Itakura, Kazunori
2014-09-01
In the early stage of heavy ion collisions, there appear extraordinarily strong (color) EM fields. In the presence of such strong fields, we encounter essentially new phenomena that are not observed in the vacuum: Among those is fermion pair creation from the vacuum. In this talk, we consider fermion pair creation from the vacuum in a strong electric field with finite duration. Employing the Sauter-type pulsed electric field with height E0 and width τ, we demonstrate explicitly the interplay between the non-perturbative and perturbative aspects of the pair creation in a strong field with finite duration. We identify that two dimensionless parameters ν = | g E0 | τ2 and γ = | g E0 | τ / m characterize the importance of multiple interactions with the field and the transition from the perturbative to the non-perturbative regime. We also show that the pair creation is enhanced compared to Schwinger's formula when the field strength is relativity weak | g E0 | / m2 < 1 and the pulse duration is relatively short mτ < 1 , and reveal that the enhancement is predominantly described by the lowest order perturbation with a single photon. We also discuss some recent developments and applications.
QCD spectroscopy and quark mass renormalisation in external magnetic fields with Wilson fermions
Bali, Gunnar; Endrodi, Gergely; Glaessle, Benjamin
2015-01-01
We study the change of the QCD spectrum of low-lying mesons in the presence of an external magnetic field using Wilson fermions in the quenched approximation. Motivated by qualitative differences observed in the spectra of overlap and Wilson fermions for large magnetic fields, we investigate the dependence of the additive quark mass renormalisation on the magnetic field. We provide evidence that the magnetic field changes the critical quark mass both in the free case and on our quenched ensemble. The associated change of the bare quark mass with the magnetic field affects the spectrum and is relevant for the magnetic field dependence of a number of related quantities. We derive Ward identities for lattice and continuum QCD+QED from which we can extract the current quark masses. We also report on a first test of the tuning of the quark masses with the magnetic field using the current quark masses, and show that this tuning resolves the qualitative discrepancy between the Wilson and overlap spectra.
N{sub f}=1 QCD in external magnetic fields: staggered fermions
Energy Technology Data Exchange (ETDEWEB)
Cea, Paolo [INFN, Sezione di Bari, Via Amendola 173, I-70126 Bari (Italy); Dipartimento di Fisica dell’Università di Bari, Via Amendola 173, I-70126 Bari (Italy); Cosmai, Leonardo [INFN, Sezione di Bari, Via Amendola 173, I-70126 Bari (Italy)
2015-12-10
We investigate N{sub f}=1 QCD in external magnetic fields on the lattice. The background field is introduced by means of the so-called Schrödinger functional. We adopt standard staggered fermions with constant bare mass am=0.025 and magnetic fields with constant magnetic flux up to a{sup 2}eH≃2.3562. We find that the the deconfinement and chiral symmetry restoration temperatures do not depend on the strength of the applied magnetic field. Our method allow us to easily study the effects of the external magnetic fields on the QCD thermodynamics. We determine the influences of applied magnetic fields to the free energy, pressure, and equation of state of strongly interacting matter.
Keenan, Brett; Ford, Alex; Medvedev, Mikhail
2014-10-01
Plasma turbulence in some astrophysical objects (e.g., weakly magnetized collisionless shocks in GRBs and SN) has small-scale electro-magnetic field fluctuations. We study spectral characteristics of radiation produced by particles moving in such turbulence and relate it to transport properties (diffusion) of these particles. It was shown earlier that relativistic particles produce jitter radiation, which spectral characteristics are markedly different from synchrotron radiation. Here we study radiation produced by non-relativistic particles. Unlike radiation in homogeneous field, which spectrum consists of a single cyclotron harmonic, radiation in the sub-Larmor-scale turbulence reflects statistical properties of the underlying magnetic field. We present both analytical estimates and results of ab initio numerical simulations. We also show that particle propagation in such turbulence is diffusive and evaluate the diffusion coefficient. We demonstrate that the diffusion coefficient correlates with some spectral parameters. These results can be very valuable for remote diagnostics of laboratory and astrophysical plasmas. Supported by grant DOE grant DE-FG02-07ER54940 and NSF grant AST-1209665.
Renormalized Unruh-DeWitt Particle Detector Models for Boson and Fermion Fields
Hümmer, Daniel; Kempf, Achim
2016-01-01
Since quantum field theories do not possess proper position observables, Unruh-DeWitt detector models serve as a key theoretical tool for extracting localized spatio-temporal information from quantum fields. Most studies have been limited, however, to Unruh-DeWitt (UDW) detectors that are coupled linearly to a scalar bosonic field. Here, we investigate UDW detector models that probe fermionic as well as bosonic fields through both linear and quadratic couplings. In particular, we present a renormalization method that cures persistent divergencies of prior models. We then show how perturbative calculations with UDW detectors can be streamlined through the use of extended Feynman rules that include localized detector-field interactions.Our findings pave the way for the extension of previous studies of the Unruh and Hawking effects with UDW detectors, and provide new tools for studies in relativistic quantum information, for example, regarding relativistic quantum communication and studies of the entanglement st...
Higher Spin Fermionic Quantum Fields on Curved Spacetimes and their Algebraic Quantization
Muehlhoff, Rainer
2011-01-01
A first order linear differential operator for Fermionic spinor fields of arbitrary half integral spin on globally hyperbolic Lorentzian spacetime manifolds is constructed. The Cauchy problem for the resulting field equation (massive as well as massless) is shown to have unique solutions. On the spinor bundle, a natural Hermitian scalar product is constructed with respect to which the differential operator is of positive-definite type. This leads to a construction of C*-algebra representation of the canonical anti-commutation relations and thus to a quantization of the higher spin system, which does not depend on further choices. Hence, these considerations show that the well-known CAR-algebraic quantization construction by Dimock (1982) for the spin 1/2 Dirac field can naturally be generalized to Fermionic fields of higher spin, which was as yet an open question. This document is equipped with a solid introduction to the formalism of 2-spinors on curved spacetimes in an invariant fashion using abstract index...
Fermion Condensates and the Trivial Vacuum of Light-Cone Quantum Field Theory
Heinzl, T
1996-01-01
We discuss the definition of condensates within light-cone quantum field theory. As the vacuum state in this formulation is trivial, we suggest to abstract vacuum properties from the particle spectrum. The latter can in principle be calculated by solving the eigenvalue problem of the light-cone Hamiltonian. We focus on fermionic condensates which are order parameters of chiral symmetry breaking. As a paradigm identity we use the Gell-Mann-Oakes-Renner relation between the quark condensate and the observable pion mass. We examine the analogues of this relation in the `t~Hooft and Schwinger model, respectively. A brief discussion of the Nambu-Jona-Lasinio model is added.
Zero modes of the generalized fermion-vortex system in a magnetic field
Lu, Chi-Ken; Seradjeh, Babak
2014-06-01
We show that Dirac fermions moving in two spatial dimensions with a generalized dispersion E ˜pN, subject to an external magnetic field and coupled to a complex scalar field carrying a vortex defect with winding number Q acquire N |Q| zero modes. This is the same as in the absence of the magnetic field. Our proof is based on selection rules in the Landau level basis that dictate the existence and the number of the zero modes. We show that the result is insensitive to the choice of geometry and is naturally extended to general field profiles, where we also derive a generalization of the Aharonov-Casher theorem. Experimental consequences of our results are briefly discussed.
Point-particle effective field theory III: relativistic fermions and the Dirac equation
Burgess, C. P.; Hayman, Peter; Rummel, Markus; Zalavári, László
2017-09-01
We formulate point-particle effective field theory (PPEFT) for relativistic spin-half fermions interacting with a massive, charged finite-sized source using a first-quantized effective field theory for the heavy compact object and a second-quantized language for the lighter fermion with which it interacts. This description shows how to determine the near-source boundary condition for the Dirac field in terms of the relevant physical properties of the source, and reduces to the standard choices in the limit of a point source. Using a first-quantized effective description is appropriate when the compact object is sufficiently heavy, and is simpler than (though equivalent to) the effective theory that treats the compact source in a second-quantized way. As an application we use the PPEFT to parameterize the leading energy shift for the bound energy levels due to finite-sized source effects in a model-independent way, allowing these effects to be fit in precision measurements. Besides capturing finite-source-size effects, the PPEFT treatment also efficiently captures how other short-distance source interactions can shift bound-state energy levels, such as due to vacuum polarization (through the Uehling potential) or strong interactions for Coulomb bound states of hadrons, or any hypothetical new short-range forces sourced by nuclei.
Fry, M. P.
2001-01-01
The current status of bounds on and limits of fermion determinants in two, three and four dimensions in QED and QCD is reviewed. A new lower bound on the two-dimensional QED determinant is derived. An outline of the demonstration of the continuity of this determinant at zero mass when the background magnetic field flux is zero is also given.
Leclerc, M
2012-01-01
We introduce a symmetric Poisson bracket that allows us to describe anticommuting fields on a classical level in the same way as commuting fields, without the use of Grassmann variables. By means of a simple example, we show how the Dirac bracket for the elimination of the second class constraints can be introduced, how the classical Hamiltonian equations can be derived and how quantization can be achieved through a direct correspondence principle. Finally, we show that the semiclassical limit of the corresponding Schroedinger equation leads back to the Hamilton-Jacobi equation of the classical theory. Summarizing, it is shown that the relations between classical and quantum theory are valid for fermionic fields in exactly the same way as in the bosonic case, and that there is no need to introduce anticommuting variables on a classical level.
Lin, M. C.; Chang, P. C.; Lu, P. S.; Verboncoeur, J. P.
2011-10-01
Influence of ion effects on a space charge limited field emission flow has been studied systematically, by employing both analytical and numerical approaches. In our model, the field emission of electrons is described by the Fowler-Nordheim equation. The cathode plasma and surface properties are considered within the framework of an effective work function approximation. Ionization effects at the anode as well as electron space-charge effects are described by Poisson's equation coupled with the energy conservation equation including the relativistic effects. The calculations are carried out self-consistently to yield the steady states of the bipolar flow. The electric field on the cathode surface is found to be saturated due to space charge effects and is determined by the effective work function approximately. In addition, the upstream ion current bas been treated as a tuning parameter. It is found that the field emission currents in the presence of saturated ion currents can be enhanced to be nearly 1.8, 1.5, and 1.4 times of the cases with no upstream ion current in non-relativistic, intermediate, and ultra-relativistic regimes, respectively. The solutions have also been verified using 1D PIC simulations, as implemented in the OOPD1 code developed by PTSG of UC Berkeley. Work supported by the National Science Council, Taiwan, R.O.C. under Grant No. NSC 96-2112-M-030-004-MY3, National Center for Theoretical Sciences, and National Center for High-Performance Computing, Taiwan, ROC which provides the computing resources.
Ayala, Alejandro; Gutierrez, Enif; Raya, Alfredo; Sanchez, Angel
2010-01-01
We study chiral symmetry breaking for relativistic fermions, described by a parity violating Lagrangian in 2+1-dimensions, in the presence of a heat bath and a uniform external magnetic field. Working within their four-component formalism allows for the inclusion of both parity-even and -odd mass terms. Therefore, we can define two types of fermion anti-fermion condensates. For a given value of the magnetic field, there exist two different critical temperatures which would render one of these condensates identically zero, while the other would survive. Our analysis is completely general: it requires no particular simplifying hierarchy among the energy scales involved, namely, bare masses, field strength and temperature. However, we do reproduce some earlier results, obtained or anticipated in literature, corresponding to special kinematical regimes for the parity conserving case. Relating the chiral condensate to the one-loop effective Lagrangian, we also obtain the magnetization and the pair production rate ...
Do non-relativistic neutrinos constitute the dark matter?
Nieuwenhuizen, T.M.
2009-01-01
The dark matter of the Abell 1689 Galaxy Cluster is modeled by thermal, non-relativistic gravitating fermions and its galaxies and X-ray gas by isothermal distributions. A fit yields a mass of h(70)(1/2) (12/(g) over bar)(1)/(4) 1.445(30) eV. A dark-matter fraction Omega(nu) = h(70)(-3/2) 0.1893(39)
Energy Technology Data Exchange (ETDEWEB)
Snoek, M; Titvinidze, I; Toeke, C; Hofstetter, W [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, 60438 Frankfurt/Main (Germany); Byczuk, K [Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute for Physics, University of Augsburg, 86135 Augsburg (Germany)], E-mail: snoek@itp.uni-frankfurt.de
2008-09-15
We apply dynamical mean-field theory to strongly interacting fermions in an inhomogeneous environment. With the help of this real-space dynamical mean-field theory (R-DMFT) we investigate antiferromagnetic states of repulsively interacting fermions with spin1/2 in a harmonic potential. Within R-DMFT, antiferromagnetic order is found to be stable in spatial regions with total particle density close to one, but persists also in parts of the system where the local density significantly deviates from half filling. In systems with spin imbalance, we find that antiferromagnetism is gradually suppressed and phase separation emerges beyond a critical value of the spin imbalance.
Non-relativistic particles in a thermal bath
Directory of Open Access Journals (Sweden)
Vairo Antonio
2014-04-01
Full Text Available Heavy particles are a window to new physics and new phenomena. Since the late eighties they are treated by means of effective field theories that fully exploit the symmetries and power counting typical of non-relativistic systems. More recently these effective field theories have been extended to describe non-relativistic particles propagating in a medium. After introducing some general features common to any non-relativistic effective field theory, we discuss two specific examples: heavy Majorana neutrinos colliding in a hot plasma of Standard Model particles in the early universe and quarkonia produced in heavy-ion collisions dissociating in a quark-gluon plasma.
Complete Form of Fermion Self-energy in NJL Model with External Magnetic Field
Shi, Song; Cui, Zhu-Fang; Xia, Yong-Hui; Zong, Hong-Shi
2016-01-01
In this paper, we aim to study the complete form of self-energy in fermion propagator within two-flavor NJL model in the case of finite temperature, chemical potential and external magnetic field. Through self-consistency analysis we prove that the self-energy is not simply proportional to dynamical mass in the presence of chemical potential, moreover, it could be more complicated after introducing external magnetic field. We find out the appropriate and complete form of self-energy and establish new gap equations. The numerical results show that the dynamical mass only has small quantitative modification rather than qualitative change by using these new gap equations, but the new self-energy does generate split in the dispersion relation with fixed momentum and Landau level.
Statistical Cosmological Fermion Systems With Interparticle Fantom Scalar Interaction
Ignat'ev, Yurii; Ignatyev, Dmitry
2016-01-01
The article represents a research of the cosmological evolution of fermion statistical systems with fantom scalar interaction where "kinetic" term's contribution to the total energy of a scalar field is negative. As a result of analytical and numerical simulation of such systems it has been revealed a existence of four possible scenarios depending on parameters of the system and initial conditions. Among these scenarios there are scenarios with an early, intermediate and late non-relativistic stages of the cosmological evolution, all of which also have necessary inflation stage.
Stability conditions for fermionic Ising spin-glass models in the presence of a transverse field
Magalhães, S. G.; Zimmer, F. M.; Morais, C. V.
2009-06-01
The stability of a spin-glass (SG) phase is analyzed in detail for a fermionic Ising SG (FISG) model in the presence of a magnetic transverse field Γ. The fermionic path integral formalism, replica method and static approach have been used to obtain the thermodynamic potential within one step replica symmetry breaking ansatz. The replica symmetry (RS) results show that the SG phase is always unstable against the replicon. Moreover, the two other eigenvalues λ± of the Hessian matrix (related to the diagonal elements of the replica matrix) can indicate an additional instability to the SG phase, which enhances when Γ is increased. Therefore, this result suggests that the study of the replicon cannot be enough to guarantee the RS stability in the present quantum FISG model, especially near the quantum critical point. In particular, the FISG model allows changing the occupation number of sites, so one can get a first order transition when the chemical potential exceeds a certain value. In this region, the replicon and the λ± indicate instability problems for the SG solution close to all ranges of a first order boundary.
Bertrand, J.; Gaveau, B.; Rideau, G.
1985-05-01
Quantum field evolutions are written as expectation values with respect to Poisson processes in two simple models: interaction of two boson fields (with conservation of the number of particles in one field) and interaction of a boson with a fermion field. The introduction of a cut-off ensures that the expectation values are well-defined.
Energy Technology Data Exchange (ETDEWEB)
Bertrand, J. (Paris-7 Univ., 75 (France). Lab. de Physique Theorique et Mathematique); Gaveau, B.; Rideau, G. (Paris-6 Univ., 75 (France). Dept. de Mathematiques)
1985-05-01
Quantum field evolutions are written as expectation values with respect to Poisson processes in two simple models; interaction of two boson fields (with conservation of the number of particles in one field) and interaction of a boson with a fermion field. The introduction of a cutt-off ensures that the expectation values are well-defined.
Holographic thermalization from nonrelativistic branes
Roychowdhury, Dibakar
2016-05-01
In this paper, based on the fundamental principles of gauge/gravity duality and considering a global quench, we probe the physics of thermalization for certain special classes of strongly coupled nonrelativistic quantum field theories that are dual to an asymptotically Schrödinger D p brane space time. In our analysis, we note that during the prelocal stages of the thermal equilibrium the entanglement entropy has a faster growth in time compared to its relativistic cousin. However, it shows a linear growth during the postlocal stages of thermal equilibrium where the so-called tsunami velocity associated with the linear growth of the entanglement entropy saturates to that of its value corresponding to the relativistic scenario. Finally, we explore the saturation region and it turns out that one must constraint certain parameters of the theory in a specific way in order to have discontinuous transitions at the point of saturation.
Extended Galilean symmetries of non-relativistic strings
Batlle, Carles; Gomis, Joaquim; Not, Daniel
2017-02-01
We consider two non-relativistic strings and their Galilean symmetries. These strings are obtained as the two possible non-relativistic (NR) limits of a relativistic string. One of them is non-vibrating and represents a continuum of non-relativistic massless particles, and the other one is a non-relativistic vibrating string. For both cases we write the generator of the most general point transformation and impose the condition of Noether symmetry. As a result we obtain two sets of non-relativistic Killing equations for the vector fields that generate the symmetry transformations. Solving these equations shows that NR strings exhibit two extended, infinite dimensional space-time symmetries which contain, as a subset, the Galilean symmetries. For each case, we compute the associated conserved charges and discuss the existence of non-central extensions.
Extended Galilean symmetries of non-relativistic strings
Batlle, Carles; Not, Daniel
2016-01-01
We consider two non-relativistic strings and their Galilean symmetries. These strings are obtained as the two possible non-relativistic (NR) limits of a relativistic string. One of them is non-vibrating and represents a continuum of non-relativistic massless particles, and the other one is a non-relativistic vibrating string. For both cases we write the generator of the most general point transformation and impose the condition of Noether symmetry. As a result we obtain two sets of non-relativistic Killing equations for the vector fields that generate the symmetry transformations. Solving these equations shows that NR strings exhibit two extended, infinite dimensional space-time symmetries which contain, as a subset, the Galilean symmetries. For each case, we compute the associated conserved charges and discuss the existence of non-central extensions.
Tsybul'nik, V. A.; Roshchupkin, S. P.
2014-08-01
We theoretically study the gain coefficient for a electromagnetic field, in the scattering of nonrelativistic electrons by ions in a elliptically polarized light wave. We obtain a simple analytical expression for a field amplification constant in logarithmic approach to an arbitrary angle of the initial electron. The formula supplements and extends the domain of applicability of the known Marcuse formula for the linear polarization in the presence of a weak field. It is demonstrated that the maximum gain is reached when the initial electron velocity directs along the major semi-axis of the polarization ellipse. In the range of optical frequencies, the gain coefficient of the laser radiation can be significant for relatively high powers of electron beams. Obtained results may be experimentally verified, for example, by the scientific facilities at the SLAC National Accelerator Laboratory and FAIR (Facility for Antiproton and Ion Research, Darmstadt, Germany).
Roshchupkin, S. P.
2009-08-01
The amplification factor of the electromagnetic field is theoretically studied for the scattering of nonrelativistic electrons by ions in the presence of the field of the elliptically polarized electromagnetic wave. A simple analytical formula for the gain is derived for the medium-intensity range. The formula supplements and extends the domain of applicability of the known Marcuse formula for the linear polarization in the presence of a weak field. It is demonstrated that the maximum gain is reached when the initial electron velocities belong to the polarization plane of the electromagnetic wave. In the range of optical frequencies, the amplification factor of the laser radiation can be significant for relatively high powers of electron beams.
Aldaihan, S; Long, J C; Snow, W M
2016-01-01
Various theories beyond the Standard Model predict new particles with masses in the sub-eV range with very weak couplings to ordinary matter which can possess spin-dependent couplings to electrons and nucleons. Present laboratory constraints on exotic spin-dependent interactions with pseudoscalar and axial couplings for exchange boson masses between meV and eV are very poor compared to constraints on spin-independent interactions in the same mass range arising from spin-0 and spin-1 boson exchange. It is therefore interesting to analyze in a general way how one can use the strong experimental bounds on spin-independent interactions to also constrain spin-dependent interactions by considering higher-order exchange processes. The exchange of a pair of bosons between two fermions with spin-dependent couplings will possess contributions which flip spins twice and thereby generate a polarization-independent interaction energy which can add coherently between two unpolarized objects. In this paper we derive the dom...
Mean-field study of the heavy-fermion metamagnetic transition
Viola Kusminskiy, S.; Beach, K. S. D.; Castro Neto, A. H.; Campbell, D. K.
2008-03-01
We investigate the evolution of the heavy-fermion ground state under application of a strong external magnetic field. We present a richer version of the usual hybridization mean-field theory that allows for hybridization in both the singlet and triplet channels and incorporates a self-consistent Weiss field. We show that for a magnetic field strength B* , a filling-dependent fraction of the zero-field hybridization gap, the spin up quasiparticle band becomes fully polarized—an event marked by a sudden jump in the magnetic susceptibility. The system exhibits a kind of quantum rigidity in which the susceptibility (and several other physical observables) is insensitive to further increases in field strength. This behavior ends abruptly with the collapse of the hybridization order parameter in a first-order transition to the normal metallic state. We argue that the feature at B* corresponds to the “metamagnetic transition” in YbRh2Si2 . Our results are in good agreement with recent experimental measurements.
On the interplay between heavy-fermion and soft crystal field excitations in Kondo lattices
Energy Technology Data Exchange (ETDEWEB)
Kagan, Yu.; Kikoin, K.A.; Mishchenko, A.S. [Rossijskij Nauchnyj Tsentr ``Kurchatovskij Inst.``, Moscow (Russian Federation)
1997-06-13
On the grounds of the microscopic theory of heavy-fermion spin-liquids a novel description of low-energy excitation spectra in CeNiSn and related compounds is offered. The anomalous properties of orthorhombic CeNiSn and related materials are explained by the interplay between the fermi-type spinon excitations with the energy scale T{sup *}{approx}T{sub K} and the one-site crystal field excitations with the energy {Delta}{sub CF}
Iskin, Menderes
2011-01-01
PHYSICAL REVIEW A 83, 045602 (2011) Ultracold fermions in real or fictitious magnetic fields: BCS-BEC evolution and type-I–type-II transition M. Iskin1 and C. A. R. S´a de Melo2 1Department of Physics, Koc¸ University, Rumelifeneri Yolu, TR-34450 Sariyer, Istanbul, Turkey 2School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA (Received 11 March 2010; published 26 April 2011) We study ultracold neutral fermion superfluids in the presence of fictit...
Non-Relativistic Anti-Snyder Model and Some Applications
Ching, Chee Leong; Ng, Wei Khim
2016-01-01
We examine the (2+1)-dimensional Dirac equation in a homogeneous magnetic field under the non-relativistic anti-Snyder model which is relevant to deformed special relativity (DSR) since it exhibits an intrinsic upper bound of the momentum of free particles. After setting up the formalism, exact eigen solutions are derived in momentum space representation and they are expressed in terms of finite orthogonal Romanovski polynomials. There is a finite maximum number of allowable bound states due to the orthogonality of the polynomials and the maximum energy is truncated at the maximum n. Similar to the minimal length case, the degeneracy of the Dirac-Landau levels in anti- Snyder model are modified and there are states that do not exist in the ordinary quantum mechanics limit. By taking zero mass limit, we explore the motion of effective zero mass charged Fermions in Graphene like material and obtained a maximum bound of deformed parameter. Furthermore, we consider the modified energy dispersion relations and its...
Nonrelativistic anti-Snyder model and some applications
Ching, C. L.; Yeo, C. X.; Ng, W. K.
2017-01-01
In this paper, we examine the (2+1)-dimensional Dirac equation in a homogeneous magnetic field under the nonrelativistic anti-Snyder model which is relevant to doubly/deformed special relativity (DSR) since it exhibits an intrinsic upper bound of the momentum of free particles. After setting up the formalism, exact eigensolutions are derived in momentum space representation and they are expressed in terms of finite orthogonal Romanovski polynomials. There is a finite maximum number of allowable bound states nmax due to the orthogonality of the polynomials and the maximum energy is truncated at nmax. Similar to the minimal length case, the degeneracy of the Dirac-Landau levels in anti-Snyder model are modified and there are states that do not exist in the ordinary quantum mechanics limit β → 0. By taking m → 0, we explore the motion of effective massless charged fermions in graphene-like material and obtained a maximum bound of deformed parameter βmax. Furthermore, we consider the modified energy dispersion relations and its application in describing the behavior of neutrinos oscillation under modified commutation relations.
Christianson, A. D.; Bao, W.; Pagliuso, P. G.; Sarrao, J. L.; Lacerda, A. H.; Lawrence, J. M.; Kern, S.; Goremychkin, E. A.
2002-03-01
Bulk measurements by Takeuchi et al.^1 and Pagliuso et al.^2 indicate that crystal field effects may be important in understanding the exotic heavy fermion ground states exhibited by CeRhIn5 and CeIrIn_5. In an effort to understand the role of the crystal fields in these materials we have begun to study the crystal field excitations with inelastic neutron scattering. Inelastic neutron scattering probes the crystal field excitations directly. Our results indicate that a broad crystal field excitation is observed at 7 meV in CeRhIn_5. In CeIrIn_5, preliminary data suggest that the energy scale of the crystal field excitations is somewhat lower than in CeRhIn_5. We will discuss the temperature dependence of the crystal field excitations and possible crystal field level schemes as deduced from our data and compare our results with those obtained by bulk measurements. ^1T. Takeuchi et al., J. Phys. Soc. Japan 70, 877 (2001). ^2P.G. Pagliuso et al., private communication.
Universal spin-1/2 fermion field localization on a 5D braneworld
Barbosa-Cendejas, Nandinii; Mora-Luna, Refugio Rigel
2015-01-01
In this work we present a refined method for the localization of spin-$\\frac{1}{2}$ fermions on the 5D braneworld paradigm. We begin by proposing a more natural ansatz for the Yukawa coupling in the 5D bulk fermionic action, that guarantees the localization of the ground states for the 4D fermions with right or left chirality. Furthermore, we show that the fermion ground states localization allow us to show the absence of tachyonic modes in the left and right-chiral Kaluza-Klein mass spectrum. More precisely, we show that localization of gravity in the 5D braneworld implies the localization of the spin-$\\frac{1}{2}$ fermions.
New approach to nonrelativistic diffeomorphism invariance and its applications
Banerjee, Rabin
2015-01-01
A comprehensive account of a new structured algorithm for obtaining nonrelativistic diffeomorphism invariances in both space and spacetime by gauging the Galilean symmetry in a generic nonrelativistic field theoretical model is provided. % where the original (global) symmetry is localised. Various applications like the obtention of nonrelativistic diffeomorphism invariance, the introduction of Chern-Simons term and its role in fractional quantum Hall effect, induction of diffeomorphism in irrotational fluid model, abstraction of Newton-Cartan geometry and the emergence of Horava-Lifshitz gravity are discussed in details.
Thermodynamic characteristics of Fermi gases in a magnetic field
Energy Technology Data Exchange (ETDEWEB)
Lipovetskii, S.S.; Olesik, A.A.; Sekerzhitskii, V.S.
1987-11-01
Within the framework of statistical thermodynamics of equilibrium systems, general expressions are obtained for the chemical potential, pressure, and magnetic susceptibility for degenerate ideal nonrelativistic electron, proton, and neutron gases in magnetic fields, which exert no pronounced influence on the anomalous magnetic moments of the fermions.
Aharonov-Bohm effect for a fermion field in a planar black hole ''spacetime''
Energy Technology Data Exchange (ETDEWEB)
Anacleto, M.A.; Mohammadi, A. [Universidade Federal de Campina Grande, Departamento de Fisica, Caixa Postal 10071, Campina Grande, Paraiba (Brazil); Brito, F.A. [Universidade Federal de Campina Grande, Departamento de Fisica, Caixa Postal 10071, Campina Grande, Paraiba (Brazil); Universidade Federal da Paraiba, Departamento de Fisica, Caixa Postal 5008, Joao Pessoa, Paraiba (Brazil); Passos, E. [Universidade Federal de Campina Grande, Departamento de Fisica, Caixa Postal 10071, Campina Grande, Paraiba (Brazil); Universidade Federal do Rio de Janeiro, Instituto de Fisica, Caixa Postal 21945, Rio de Janeiro (Brazil)
2017-04-15
In this paper we consider the dynamics of a massive spinor field in the background of the acoustic black hole spacetime. Although this effective metric is acoustic and describes the propagation of sound waves, it can be considered as a toy model for the gravitational black hole. In this manner, we study the properties of the dynamics of the fermion field in this ''gravitational'' rotating black hole as well as the vortex background. We compute the differential cross section through the use of the partial wave approach and show that an effect similar to the gravitational Aharonov-Bohm effect occurs for the massive fermion field moving in this effective metric. We discuss the limiting cases and compare the results with the massless scalar field case. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Buchbinder, I.L., E-mail: joseph@tspu.edu.ru [Department of Theoretical Physics, Tomsk State Pedagogical University, Tomsk 634061 (Russian Federation); National Research Tomsk State University (Russian Federation); Snegirev, T.V., E-mail: snegirev@tspu.edu.ru [Department of Theoretical Physics, Tomsk State Pedagogical University, Tomsk 634061 (Russian Federation); Zinoviev, Yu.M., E-mail: Yurii.Zinoviev@ihep.ru [Institute for High Energy Physics, Protvino, Moscow Region, 142280 (Russian Federation)
2014-11-10
We construct the frame-like gauge-invariant Lagrangian formulation for massive fermionic arbitrary spin fields in three-dimensional AdS space. The Lagrangian and complete set of gauge transformations are obtained. We also develop the formalism of gauge-invariant curvatures for the massive theory under consideration and show how the Lagrangian is formulated in their terms. The massive spin-5/2 field is discussed as an example.
On intrinsic structure of wave function of fermion triplet in external monopole field
Redkov, V M
1999-01-01
Using the Weyl-Tetrode-Fock spinor formalism, the fermion triplet in the 't Hooft-Polyakov monopole field is examined all over again. Spherical solutions corresponding to the total conserved momentum J =l + S + T are constructed. The angular dependence is expressed in terms of the Wigner's functions. The radial system of 12 equations decomposes into two sub-systems by diagonalizing some complicated inversion operator. The case of minimal j = 1/2 is considered separately. A more detailed analysis is accomplished for the case of simplest monopole field: namely, the one produced by putting the Dirac potential into the non-Abelian scheme. Now a discrete operation diagonalized contains an additional complex parameter A. The same parameter enters wave functions. This quantity can manifest itself at matrix elements. In particular, there have been analyzed the N(A)-parity selection rules: those depending on the A. As shown, the A-freedom is a consequence of the existence of additional symmetry of the relevant Hamilto...
Nonrelativistic quantum X-ray physics
Hau-Riege, Stefan P
2015-01-01
Providing a solid theoretical background in photon-matter interaction, Nonrelativistic Quantum X-Ray Physics enables readers to understand experiments performed at XFEL-facilities and x-ray synchrotrons. As a result, after reading this book, scientists and students will be able to outline and perform calculations of some important x-ray-matter interaction processes. Key features of the contents are that the scope reaches beyond the dipole approximation when necessary and that it includes short-pulse interactions. To aid the reader in this transition, some relevant examples are discussed in detail, while non-relativistic quantum electrodynamics help readers to obtain an in-depth understanding of the formalisms and processes. The text presupposes a basic (undergraduate-level) understanding of mechanics, electrodynamics, and quantum mechanics. However, more specialized concepts in these fields are introduced and the reader is directed to appropriate references. While primarily benefiting users of x-ray light-sou...
Convex Decompositions of Thermal Equilibrium for Non-interacting Non-relativistic Particles
Chenu, Aurelia; Branczyk, Agata; Sipe, John
2016-05-01
We provide convex decompositions of thermal equilibrium for non-interacting non-relativistic particles in terms of localized wave packets. These quantum representations offer a new tool and provide insights that can help relate to the classical picture. Considering that thermal states are ubiquitous in a wide diversity of fields, studying different convex decompositions of the canonical ensemble is an interesting problem by itself. The usual classical and quantum pictures of thermal equilibrium of N non-interacting, non-relativistic particles in a box of volume V are quite different. The picture in classical statistical mechanics is about (localized) particles with a range of positions and velocities; in quantum statistical mechanics, one considers the particles (bosons or fermions) associated with energy eigenstates that are delocalized through the whole box. Here we provide a representation of thermal equilibrium in quantum statistical mechanics involving wave packets with a localized coordinate representation and an expectation value of velocity. In addition to derive a formalism that may help simplify particular calculations, our results can be expected to provide insights into the transition from quantum to classical features of the fully quantum thermal state.
Nishino, Hitoshi
2012-01-01
We present a system of a self-dual Yang-Mills field and a self-dual vector-spinor field with nilpotent fermionic symmetry (but not supersymmetry) in 2+2 dimensions, that generates supersymmetric integrable systems in lower dimensions. Our field content is (A_\\mu{}^I, \\psi_\\mu{}^I, \\chi^{I J}), where I and J are the adjoint indices of arbitrary gauge group. The \\chi^{I J} is a Stueckelberg field for consistency. The system has local nilpotent fermionic symmetry with the algebra \\{N_\\alpha{}^I, N_\\beta{}^J \\} = 0. This system generates supersymmetric Kadomtsev-Petviashvili equations in D=2+1, and supersymmetric Korteweg-de Vries equations in D=1+1 after appropriate dimensional reductions. We also show that a similar self-dual system in seven dimensions generates self-dual system in four dimensions. Based on our results we conjecture that lower-dimensional supersymmetric integral models can be generated by non-supersymmetric self-dual systems in higher dimensions only with nilpotent fermionic symmetries.
Eshghi, M.; Mehraban, H.; Azar, I. Ahmadi
2017-10-01
In this research, firstly, by using the new form of Dirac-Weyl equation and the series method with submitting more suitable details, the energy spectrum and wave functions of the massless Dirac fermions are calculated under the inhomogeneous and q-deformed spatially magnetic fields. Although, we discussed about the results of the energy levels, further, we obtained the wave function as the Hessenberg determinant with calculating the elements of it as exact. On the other hand, by using the Mellin-Barnes integral representation and Hurwitz zeta function, we have achieved the thermodynamic physical quantities of the Dirac-Weyl fermions in the absence of a magnetic field for inside of the graphene quantum dot. Finally, our numerical results for the wave functions and probability densities are presented too.
Yb-based heavy fermion compounds and field tuned quantum chemistry
Energy Technology Data Exchange (ETDEWEB)
Mun, Eundeok [Iowa State Univ., Ames, IA (United States)
2010-01-01
The motivation of this dissertation was to advance the study of Yb-based heavy fermion (HF) compounds especially ones related to quantum phase transitions. One of the topics of this work was the investigation of the interaction between the Kondo and crystalline electric field (CEF) energy scales in Yb-based HF systems by means of thermoelectric power (TEP) measurements. In these systems, the Kondo interaction and CEF excitations generally give rise to large anomalies such as maxima in ρ(T) and as minima in S(T). The TEP data were use to determine the evolution of Kondo and CEF energy scales upon varying transition metals for YbT_{2}Zn_{20} (T = Fe, Ru, Os, Ir, Rh, and Co) compounds and applying magnetic fields for YbAgGe and YbPtBi. For YbT_{2}Zn_{20} and YbPtBi, the Kondo and CEF energy scales could not be well separated in S(T), presumably because of small CEF level splittings. A similar effect was observed for the magnetic contribution to the resistivity. For YbAgGe, S(T) has been successfully applied to determine the Kondo and CEF energy scales due to the clear separation between the ground state and thermally excited CEF states. The Kondo temperature, T_{K}, inferred from the local maximum in S(T), remains finite as magnetic field increases up to 140 kOe. In this dissertation we have examined the heavy quasi-particle behavior, found near the field tuned AFM quantum critical point (QCP), with YbAgGe and YbPtBi. Although the observed nFL behaviors in the vicinity of the QCP are different between YbAgGe and YbPtBi, the constructed H-T phase diagram including the two crossovers are similar. For both YbAgGe and YbPtBi, the details of the quantum criticality turn out to be complicated. We expect that YbPtBi will provide an additional example of field tuned quantum criticality, but clearly there are further experimental investigations left and more ideas needed to understand the basic physics of field-induced quantum
Complex fermion coherent states
Tyc, T; Sanders, B C; Oliver, W D; Tyc, Tomas; Hamilton, Brett; Sanders, Barry C.; Oliver, William D.
2005-01-01
Whereas boson coherent states provide an elegant, intuitive and useful representation, we show that the desirable features of boson coherent states do not carry over very well to fermion fields unless one is prepared to use exotic approaches such as Grassmann fields. Specifically, we identify four appealing properties of boson coherent states (eigenstate of annihilation operator, displaced vacuum state, preservation of product states under linear coupling, and factorization of correlators) and show that fermion coherent states, and approximations to fermion coherent states, defined over the complex field, do not behave well for any of these four criteria.
Elizalde, E; Odintsov, S D; Shilnov, Yu I; Shil'nov, Yu. I.
1998-01-01
A four-fermion model with additional higher-derivative terms is investigated in an external electromagnetic field. The effective potential in the leading order of large-N expansion is calculated in external constant magnetic and electric fields. It is shown that, in contrast to the former results concerning the universal character of "magnetic catalysis" in dynamical symmetry breaking, in the present higher-derivative model the magnetic field restores chiral symmetry broken initially on the tree level. Numerical results describing a second-order phase transition that accompanies the symmetry restoration at the quantum level are presented.
Gukelberger, Jan; Hafermann, Hartmut
2016-01-01
The dual-fermion approach provides a formally exact prescription for calculating properties of a correlated electron system in terms of a diagrammatic expansion around dynamical mean-field theory (DMFT). It can address the full range of interactions, the lowest order theory is asymptotically exact in both the weak- and strong-coupling limits, and the technique naturally incorporates long-range correlations beyond the reach of current cluster extensions to DMFT. Most practical implementations, however, neglect higher-order interaction vertices beyond two-particle scattering in the dual effective action and further truncate the diagrammatic expansion in the two-particle scattering vertex to a leading-order or ladder-type approximation. In this work we compute the dual-fermion expansion for the Hubbard model including all diagram topologies with two-particle interactions to high orders by means of a stochastic diagrammatic Monte Carlo algorithm. We use benchmarking against numerically exact Diagrammatic Determin...
Karbstein, Felix
2007-01-01
We use 1+1 dimensional large N Gross-Neveu models as a laboratory to derive microscopically effective Lagrangians for positive energy fermions only. When applied to baryons, the Euler-Lagrange equation for these effective theories assumes the form of a non-linear Dirac equation. Its solution reproduces the full semi-classical results including the Dirac sea to any desired accuracy. Dynamical effects from the Dirac sea are encoded in higher order derivative terms and multi-fermion interactions with perturbatively calculable, finite coefficients. Characteristic differences between models with discrete and continuous chiral symmetry are observed and clarified.
Fermionic T-duality in fermionic double space
Nikolić, B.; Sazdović, B.
2017-04-01
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 θbarα with the corresponding fermionic T-dual ones, ϑα and ϑbarα, 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.
Nibbelink, Stefan Groot
2016-01-01
Inspired by the tachyon-free non-supersymmetric heterotic SO(16)xSO(16) string we consider a special class of non-supersymmetric field theories: Those that can be obtained from supersymmetric field theories by supersymmetry breaking twists. We argue that such theories, like their supersymmetric counter parts, may still possess some fermionic symmetries as left-overs of the super gauge transformations and have special one-loop non-renormalization properties due to holomorphicity. In addition, we extend the supergraph techniques to these theories to calculate some explicit supersymmetry-breaking corrections.
Groot Nibbelink, Stefan; Parr, Erik
2016-08-01
Inspired by the tachyon-free nonsupersymmetric heterotic SO (16 )×SO (16 ) string we consider a special class of nonsupersymmetric field theories: those that can be obtained from supersymmetric field theories by supersymmetry-breaking twists. We argue that such theories, like their supersymmetric counterparts, may still possess some fermionic symmetries as leftovers of the supergauge transformations and have special one-loop nonrenormalization properties due to holomorphicity. In addition, we extend the supergraph techniques to these theories to calculate some explicit supersymmetry-breaking corrections.
Rostam Zadeh, S.; Gousheh, S. S.
2016-09-01
We study the simultaneous evolution of electron, neutrino, and quark asymmetries and large-scale hypermagnetic fields in the symmetric phase of the electroweak plasma in the temperature range 100 GeV ≤T ≤10 TeV , taking into account the chirality flip processes via inverse Higgs decays and fermion number violation due to Abelian anomalies. We present a derivation of the coefficient of the Chern-Simons term for the hypercharge gauge field, showing that the left-handed and right-handed components of each fermion species contribute with opposite sign. This is in contrast to the results presented in some of the previous works. The UY(1 ) Chern-Simons term affects the resulting anomalous magnetohydrodynamic equations. We solve the resulting coupled evolution equations for the lepton and baryon asymmetries, as well as the hypermagnetic field to obtain their time evolution along with their values at the electroweak phase transition (TEW˜100 GeV ) for a variety of critical ranges for their initial values at T =10 TeV . We first investigate the results of this sign change by directly comparing our results with those obtained in one of the previous works and find that matter asymmetry generation increases considerably in the presence of a strong hypermagnetic field. Furthermore, we find that a strong hypermagnetic field can generate matter asymmetry starting from absolutely zero asymmetry, while matter asymmetry can generate a hypermagnetic field provided the initial value of the latter is nonzero.
Fermionic T-duality in fermionic double space
Nikolic, Bojan
2016-01-01
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 repersented as permutation of the fermionic coordinates $\\theta^\\alpha$ and $\\bar\\theta^\\alpha$ with the corresponding fermionic T-dual ones, $\\vartheta_\\alpha$ and $\\bar\\vartheta_\\alpha$, respectively. Demanding that T-dual transformation law has the same form as inital one, we obtain the known form of the fermionic T-dual NS-R i 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...
A CPT-even Lorentz-violating nonminimal coupling between fermions and photons
Casana, R; Santos, E Passos F E P Dos; Silva, E O
2013-01-01
We propose a CPT-even and Lorentz-violating dimension-five nonminimal coupling between fermionic and gauge fields, involving the CPT-even and Lorentz-violating gauge tensor of the Standard-Model Extension. This nonminimal coupling modifies the nonrelativistic regime of Dirac particles, inducing new effects such as an electric-Zeeman-like spectrum splitting and an anomalous-like contribution to the electron magnetic moment. These new effects allow to constrain the magnitude of this nonminimal coupling in 1 part in $10^{16}.$
a Cpt-Even Lorentz-Violating Nonminimal Coupling Between Fermions and Photons
Casana, R.; Ferreira, M. M.; Dos Santos, F. E. P.; Silva, E. O.; Passos, E.
2014-01-01
We propose a CPT-even and Lorentz-violating dimension-five nonminimal coupling between fermionic and gauge fields, involving the CPT-even and Lorentz-violating gauge tensor of the Standard-Model Extension. This nonminimal coupling modifies the nonrelativistic regime of Dirac particles, inducing new effects such as an electric-Zeeman-like spectrum splitting and an anomalous-like contribution to the electron magnetic moment. These new effects allow to constrain the magnitude of this nonminimal coupling in 1 part in 1016.
D-Dimensional Dirac Fermions BEC-BCS Crossover Thermodynamics
Institute of Scientific and Technical Information of China (English)
CHEN Ji-Sheng
2007-01-01
An effective relativistic continuum massive Proca Lagrangian action is used to account for the Lorentz vector condensation effects on the equation of state of the strongly interacting fermions system. The interior quantum fluctuation effects are incorporated as an external field approximation indirectly through a fictive generalized Thomson Problem counterterm background. The general analytical formulas for the d-dimensional thermodynamics are given near the unitary limit region. In the non-relativistic limit for d = 3, the universal dimensionless coefficient ξ = 4/9 and energy gap △/εf = 5/ 18 are reasonably consistent with the existing theoretical and experimental results. In the unitary limit for d = 2 and T = 0, the universal coefficient can even approach the extreme occasion ξ = 0 corresponding to the infinite effective fermion mass m* = ∞, which can be mapped to the strongly coupled two-dimensional electrons and is quite similar to the three-dimensional Bose-Einstein condensation of ideal boson gas. Instead, for d = 1, the universal coefficient ξ is negative, implying the non-existence of phase transition from superfluidity to normal state. The solutions manifest the quantum Ising universal class characteristic of the strongly coupled unitary fermions gas.
Least-Order Torsion-Gravity for Fermion Fields, and the Non-Linear Potentials in the Standard Models
Fabbri, Luca
2014-01-01
We will consider least-order torsional completion of gravity for a spacetime filled with fermionic Dirac matter fields, and we study the effects of the background-induced non-linear potentials for the matter field themselves, in terms of their effects for both standard models of physics: from the one of cosmology to that of particles, we will discuss the mechanisms of generation of the cosmological constant and particles masses as well as the phenomenology of leptonic weak-like forces and neutrino oscillations, the problem of zero-point energy, how there can be neutral massive fields as candidates for dark matter, and gravitationally-induced singularity formation; we will show the way in which all these different effects can nevertheless be altogether described in terms of just a single model, which will be thoroughly discussed in the end.
Ground State Energy of Unitary Fermion Gas with the Thomson Problem Approach
Institute of Scientific and Technical Information of China (English)
CHEN Ji-Sheng
2007-01-01
The dimensionless universal coefficient § defines the ratio of the unitary fermions energy density to that for the ideal non-interacting ones in the non-relativistic limit with T = 0. The classical Thomson problem is taken as a nonperturbative quantum many-body arm to address the ground state energy including the Iow energy nonlinear quantum fluctuation/correlation effects. With the relativistic Dirac continuum field theory formalism, the concise expression for the energy density functional of the strongly interacting limit fermions at both finite temperature and density is obtained. Analytically, the universal factor is calculated to be § = 4/9. The energy gap is △ = 5/18 k2f/(2m).
Spacetime Variation of Lorentz-Violation Coefficients at Nonrelativistic Scale
Lane, Charles D
2016-01-01
When the Standard-Model Extension (SME) is applied in curved spacetime, the Lorentz-violation coefficients must depend on spacetime position. This work describes some of the consequences of this spacetime variation. We focus on effects that appear at a nonrelativistic scale and extract sensitivity of completed experiments to derivatives of SME coefficient fields.
Thermal quantum electrodynamics of nonrelativistic charged fluids.
Buenzli, Pascal R; Martin, Philippe A; Ryser, Marc D
2007-04-01
The theory relevant to the study of matter in equilibrium with the radiation field is thermal quantum electrodynamics (TQED). We present a formulation of the theory, suitable for nonrelativistic fluids, based on a joint functional integral representation of matter and field variables. In this formalism cluster expansion techniques of classical statistical mechanics become operative. They provide an alternative to the usual Feynman diagrammatics in many-body problems, which is not perturbative with respect to the coupling constant. As an application we show that the effective Coulomb interaction between quantum charges is partially screened by thermalized photons at large distances. More precisely one observes an exact cancellation of the dipolar electric part of the interaction, so that the asymptotic particle density correlation is now determined by relativistic effects. It still has the r(-6) decay typical for quantum charges, but with an amplitude strongly reduced by a relativistic factor.
Thermal quantum electrodynamics of nonrelativistic charged fluids
Buenzli, Pascal R.; Martin, Philippe A.; Ryser, Marc D.
2007-04-01
The theory relevant to the study of matter in equilibrium with the radiation field is thermal quantum electrodynamics (TQED). We present a formulation of the theory, suitable for nonrelativistic fluids, based on a joint functional integral representation of matter and field variables. In this formalism cluster expansion techniques of classical statistical mechanics become operative. They provide an alternative to the usual Feynman diagrammatics in many-body problems, which is not perturbative with respect to the coupling constant. As an application we show that the effective Coulomb interaction between quantum charges is partially screened by thermalized photons at large distances. More precisely one observes an exact cancellation of the dipolar electric part of the interaction, so that the asymptotic particle density correlation is now determined by relativistic effects. It still has the r-6 decay typical for quantum charges, but with an amplitude strongly reduced by a relativistic factor.
Magnetic Structure of the Heavy-fermion Compound CeAuSb2 in Zero-field
Marcus, Guy G.; Kim, Dae-Jeong; Lee, Hannoh; Fisk, Zachary; Rodriguez-Rivera, Jose A.; Broholm, Collin L.
2015-03-01
We have used neutron diffraction to determine the zero-field magnetic structure of the heavy-fermion compound CeAuSb2. Below TN ~ 6 . 2 K, we observe the development of antiferromagnetic Bragg diffraction consistent with previous transport and magnetization measurements. The intensities observed at 7 magnetic satellite locations indicate the staggered magnetization is predominantly along the c-axis. The maximum moment size is 1 . 15 +/- 0 . 08μB which is large compared with the 0 . 4μB moment in the iso-structural heavy fermion ferromagnet CeAgSb2. This suggests that the antiferromagnetic CeAuSb2 is deeper into a magnetic phase. The spin structure, due mainly to the Ce-4f sites, is described as a transverse polarized spin density wave with an incommensurate component of the wave vector in the basal plane. We will discuss these results and bulk measurements in terms of an ANNNI model and effective near neighbor exchange interactions. The work at IQM was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Material Sciences and Engineering under Grant No. DE-FG02-08ER46544. GGM also acknowledges support from the NSF-GRFP Grant No. DGE-1232825.
Broecker, Peter; Trebst, Simon
2016-12-01
In the absence of a fermion sign problem, auxiliary-field (or determinantal) quantum Monte Carlo (DQMC) approaches have long been the numerical method of choice for unbiased, large-scale simulations of interacting many-fermion systems. More recently, the conceptual scope of this approach has been expanded by introducing ingenious schemes to compute entanglement entropies within its framework. On a practical level, these approaches, however, suffer from a variety of numerical instabilities that have largely impeded their applicability. Here we report on a number of algorithmic advances to overcome many of these numerical instabilities and significantly improve the calculation of entanglement measures in the zero-temperature projective DQMC approach, ultimately allowing us to reach similar system sizes as for the computation of conventional observables. We demonstrate the applicability of this improved DQMC approach by providing an entanglement perspective on the quantum phase transition from a magnetically ordered Mott insulator to a band insulator in the bilayer square lattice Hubbard model at half filling.
Non-Relativistic Spacetimes with Cosmological Constant
Aldrovandi, R.; Barbosa, A. L.; Crispino, L.C.B.; Pereira, J. G.
1998-01-01
Recent data on supernovae favor high values of the cosmological constant. Spacetimes with a cosmological constant have non-relativistic kinematics quite different from Galilean kinematics. De Sitter spacetimes, vacuum solutions of Einstein's equations with a cosmological constant, reduce in the non-relativistic limit to Newton-Hooke spacetimes, which are non-metric homogeneous spacetimes with non-vanishing curvature. The whole non-relativistic kinematics would then be modified, with possible ...
Relativistic and non-relativistic geodesic equations
Energy Technology Data Exchange (ETDEWEB)
Giambo' , R.; Mangiarotti, L.; Sardanashvily, G. [Camerino Univ., Camerino, MC (Italy). Dipt. di Matematica e Fisica
1999-07-01
It is shown that any dynamic equation on a configuration space of non-relativistic time-dependent mechanics is associated with connections on its tangent bundle. As a consequence, every non-relativistic dynamic equation can be seen as a geodesic equation with respect to a (non-linear) connection on this tangent bundle. Using this fact, the relationships between relativistic and non-relativistic equations of motion is studied.
Phantom cosmologies and fermions
Chimento, Luis P; Forte, Monica; Kremer, Gilberto M
2007-01-01
Form invariance transformations can be used for constructing phantom cosmologies starting with conventional cosmological models. In this work we reconsider the scalar field case and extend the discussion to fermionic fields, where the "phantomization" process exhibits a new class of possible accelerated regimes.
Microscopic picture of non-relativistic classicalons
Energy Technology Data Exchange (ETDEWEB)
Berkhahn, Felix; Müller, Sophia; Niedermann, Florian; Schneider, Robert, E-mail: felix.berkhahn@physik.lmu.de, E-mail: sophia.x.mueller@physik.uni-muenchen.de, E-mail: florian.niedermann@physik.lmu.de, E-mail: robert.bob.schneider@physik.uni-muenchen.de [Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 Munich (Germany)
2013-08-01
A theory of a non-relativistic, complex scalar field with derivatively coupled interaction terms is investigated. This toy model is considered as a prototype of a classicalizing theory and in particular of general relativity, for which the black hole constitutes a prominent example of a classicalon. Accordingly, the theory allows for a non-trivial solution of the stationary Gross-Pitaevskii equation corresponding to a black hole in the case of GR. Quantum fluctuations on this classical background are investigated within the Bogoliubov approximation. It turns out that the perturbative approach is invalidated by a high occupation of the Bogoliubov modes. Recently, it was proposed that a black hole is a Bose-Einstein condensate of gravitons that dynamically ensures to stay at the verge of a quantum phase transition. Our result is understood as an indication for that claim. Furthermore, it motivates a non-linear numerical analysis of the model.
Energy Technology Data Exchange (ETDEWEB)
Szirmai, G.; Szirmai, E. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); Research Institute for Solid State Physics and Optics, P.O. Box 49, H-1525 Budapest (Hungary); Zamora, A. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); Lewenstein, M. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, Lluis Companys 23, E-08010 Barcelona (Spain)
2011-07-15
We propose an experimentally feasible setup with ultracold alkaline-earth-metal atoms to simulate the dynamics of U(1) lattice gauge theories in 2 + 1 dimensions with a Chern-Simons term. To this end we consider the ground-state properties of spin-5/2 alkaline-earth-metal fermions in a honeycomb lattice. We use the Gutzwiller projected variational approach in the strongly repulsive regime in the case of filling 1/6. The ground state of the system is a chiral spin-liquid state with 2{pi}/3 flux per plaquette, which violates time-reversal invariance. We demonstrate that due to the breaking of time-reversal symmetry the system exhibits quantum Hall effect and chiral edge states. We relate the experimentally accessible spin fluctuations to the emerging gauge-field dynamics. We discuss also properties of the lowest energy competing orders.
Energy Technology Data Exchange (ETDEWEB)
Amour, L. [Reims Univ., Lab. de Mathematiques EDPPM, FRE-CNRS 3111, 51 (France); Faupin, J. [Aarhus Univ., Institut for Matematiske Fag (Denmark); Grebert, B. [Nantes Univ, Lab. de Mathematiques Jean-Leray, UMR-CNRS 6629 (France); Guillot, J.C. [Ecole Polytechnique, Centre de Mathematiques Appliquees, UMR-CNRS 7641, 91 - Palaiseau (France)
2008-10-15
We consider a non-relativistic electron interacting with a classical magnetic field pointing along the x{sub 3}-axis and with a quantized electromagnetic field. The system is translation invariant in the x{sub 3}-direction and the corresponding Hamiltonian has a decomposition H {approx_equal}{integral}{sub R}{sup +}H(P{sub 3})dP{sub 3}. For a fixed momentum P{sub 3} sufficiently small, we prove that H(P{sub 3}) has a ground state in the Fock representation if and only if E'(P{sub 3})=0, where P{sub 3} {yields}E'(P{sub 3}) is the derivative of the map P{sub 3}{yields}E(P{sub 3})=inf{sigma}(H(P{sub 3})). If E'(P{sub 3}){ne}0, we obtain the existence of a ground state in a non-Fock representation. This result holds for sufficiently small values of the coupling constant. (authors)
Lamb Shift in Nonrelativistic Quantum Electrodynamics.
Grotch, Howard
1981-01-01
The bound electron self-energy or Lamb shift is calculated in nonrelativistic quantum electrodynamics. Retardation is retained and also an interaction previously dropped in other nonrelativistic approaches is kept. Results are finite without introducing a cutoff and lead to a Lamb shift in hydrogen of 1030.9 MHz. (Author/JN)
Patrascu, Andrei T
2014-01-01
I present here a new method that allows the introduction of a discrete auxiliary symmetry in a theory in such a way that the eigenvalue spectrum of the fermion functional determinant is made up of complex conjugated pairs. The method implies a particular way of introducing and integrating over auxiliary fields related to a set of artificial shift symmetries. Gauge-fixing the artificial continuous shift symmetries in the direct and dual sector leads to the implementation of a Kahler structure over the field space. The discrete symmetry appears to be induced by the Hodge-* operator. The particular extension of the field space presented here makes the operators of the de-Rham cohomology manifest. This method implies the identification of the (anti)-BRST and dual-(anti)-BRST operators with the exterior derivative and its dual in the context of the complex de-Rham cohomology. The novelty of this method relies on the fact that the field structure is doubled two times in order to make use of a supplemental symmetry ...
Bipartite Composite Fermion States
Sreejith, G. J.; Tőke, C.; Wójs, A.; Jain, J. K.
2011-08-01
We study a class of ansatz wave functions in which composite fermions form two correlated “partitions.” These “bipartite” composite fermion states are demonstrated to be very accurate for electrons in a strong magnetic field interacting via a short-range 3-body interaction potential over a broad range of filling factors. Furthermore, this approach gives accurate approximations for the exact Coulomb ground state at 2+3/5 and 2+4/7 and is thus a promising candidate for the observed fractional quantum Hall states at the hole conjugate fractions at 2+2/5 and 2+3/7.
Fermion production during and after axion inflation
Energy Technology Data Exchange (ETDEWEB)
Adshead, Peter; Sfakianakis, Evangelos I. [Department of Physics, University of Illinois at Urbana-Champaign,Urbana, Illinois 61801 (United States)
2015-11-11
We study derivatively coupled fermions in axion-driven inflation, specifically m{sub ϕ}{sup 2}ϕ{sup 2} and monodromy inflation, and calculate particle production during the inflationary epoch and the post-inflationary axion oscillations. During inflation, the rolling axion acts as an effective chemical potential for helicity which biases the gravitational production of one fermion helicity over the other. This mechanism allows for efficient gravitational production of heavy fermion states that would otherwise be highly suppressed. Following inflation, the axion oscillates and fermions with both helicities are produced as the effective frequency of the fermion field changes non-adiabatically. For certain values of the fermion mass and axion-fermion coupling strength, the two helicity states are produced asymmetrically, resulting in unequal number-densities of left- and right-helicity fermions.
Alvarez, G.; Şen, C.; Furukawa, N.; Motome, Y.; Dagotto, E.
2005-05-01
A software library is presented for the polynomial expansion method (PEM) of the density of states (DOS) introduced in [Y. Motome, N. Furukawa, J. Phys. Soc. Japan 68 (1999) 3853; N. Furukawa, Y. Motome, H. Nakata, Comput. Phys. Comm. 142 (2001) 410]. The library provides all necessary functions for the use of the PEM and its truncated version (TPEM) in a model independent way. The PEM/TPEM replaces the exact diagonalization of the one electron sector in models for fermions coupled to classical fields. The computational cost of the algorithm is O(N)—with N the number of lattice sites—for the TPEM [N. Furukawa, Y. Motome, J. Phys. Soc. Japan 73 (2004) 1482] which should be contrasted with the computational cost of the diagonalization technique that scales as O(N). The method is applied for the first time to a double exchange model with finite Hund coupling and also to diluted spin-fermion models. Program summaryTitle of library:TPEM Catalogue identifier: ADVK Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVK Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland No. of lines in distributed program, including test data, etc.: 1707 No. of bytes in distributed program, including test data, etc.: 13 644 Distribution format:tar.gz Operating system:Linux, UNIX Number of files:4 plus 1 test program Programming language used:C Computer:PC Nature of the physical problem:The study of correlated electrons coupled to classical fields appears in the treatment of many materials of much current interest in condensed matter theory, e.g., manganites, diluted magnetic semiconductors and high temperature superconductors among others. Method of solution: Typically an exact diagonalization of the electronic sector is performed in this type of models for each configuration of classical fields, which are integrated using a classical Monte Carlo algorithm. A polynomial expansion of the density of states is able to replace the exact
Kamleh, W; Williams, A G; Kamleh, Waseem; Leinweber, Derek B.; Williams, Anthony G.; 10.1016/j.nuclphysbps.2003.12.058
2004-01-01
The use of APE smearing or other blocking techniques in fermion actions can provide many advantages. There are many variants of these fat link actions in lattice QCD currently, such as FLIC fermions. Frequently, fat link actions make use of the APE blocking technique in combination with a projection of the blocked links back into the special unitary group. This reunitarisation is often performed using an iterative maximisation of a gauge invariant measure. This technique is not differentiable with respect to the gauge field and thus prevents the use of standard Hybrid Monte Carlo simulation algorithms. The use of an alternative projection technique circumvents this difficulty and allows the simulation of dynamical fat link fermions with standard HMC and its variants.
Cold asymmetrical fermion superfluids
Energy Technology Data Exchange (ETDEWEB)
Caldas, Heron
2003-12-19
The recent experimental advances in cold atomic traps have induced a great amount of interest in fields from condensed matter to particle physics, including approaches and prospects from the theoretical point of view. In this work we investigate the general properties and the ground state of an asymmetrical dilute gas of cold fermionic atoms, formed by two particle species having different densities. We have show in a recent paper, that a mixed phase composed of normal and superfluid components is the energetically favored ground state of such a cold fermionic system. Here we extend the analysis and verify that in fact, the mixed phase is the preferred ground state of an asymmetrical superfluid in various situations. We predict that the mixed phase can serve as a way of detecting superfluidity and estimating the magnitude of the gap parameter in asymmetrical fermionic systems.
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.
Adorno, T C; Gitman, D M
2010-01-01
We construct a nonrelativistic wave equation for spinning particles in the noncommutative space (in a sense, a $\\theta$-modification of the Pauli equation). To this end, we consider the nonrelativistic limit of the $\\theta$-modified Dirac equation. To complete the consideration, we present a pseudoclassical model (\\`a la Berezin-Marinov) for the corresponding nonrelativistic particle in the noncommutative space. To justify the latter model, we demonstrate that its quantization leads to the $\\theta$-modified Pauli equation. Then, we extract $\\theta$-modified interaction between a nonrelativistic spin and a magnetic field from the $\\theta$-modified Pauli equation and construct a $\\theta$-modification of the Heisenberg model for two coupled spins placed in an external magnetic field. In the framework of such a model, we calculate the probability transition between two orthogonal EPR (Einstein-Podolsky-Rosen) states for a pair of spins in an oscillatory magnetic field and show that some of such transitions, which...
Adorno, T C; Gitman, D M
2010-01-01
We construct a nonrelativistic wave equation for spinning particles in the noncommutative space (in a sense, a $\\theta$-modification of the Pauli equation). To this end, we consider the nonrelativistic limit of the $\\theta$-modified Dirac equation. To complete the consideration, we present a pseudoclassical model (\\`a la Berezin-Marinov) for the corresponding nonrelativistic particle in the noncommutative space. To justify the latter model, we demonstrate that its quantization leads to the $\\theta$-modified Pauli equation. We extract $\\theta$-modified interaction between a nonrelativistic spin and a magnetic field from such a Pauli equation and construct a $\\theta$-modification of the Heisenberg model for two coupled spins placed in an external magnetic field. In the framework of such a model, we calculate the probability transition between two orthogonal EPR (Einstein-Podolsky-Rosen) states for a pair of spins in an oscillatory magnetic field and show that some of such transitions, which are forbidden in the...
Do non-relativistic neutrinos oscillate?
Akhmedov, Evgeny
2017-07-01
We study the question of whether oscillations between non-relativistic neutrinos or between relativistic and non-relativistic neutrinos are possible. The issues of neutrino production and propagation coherence and their impact on the above question are discussed in detail. It is demonstrated that no neutrino oscillations can occur when neutrinos that are non-relativistic in the laboratory frame are involved, except in a strongly mass-degenerate case. We also discuss how this analysis depends on the choice of the Lorentz frame. Our results are for the most part in agreement with Hinchliffe's rule.
Nonrelativistic parallel shocks in unmagnetized and weakly magnetized plasmas
Niemiec, Jacek; Bret, Antoine; Wieland, Volkmar
2012-01-01
We present results of 2D3V particle-in-cell simulations of non-relativistic plasma collisions with absent or parallel large-scale magnetic field for parameters applicable to the conditions at young supernova remnants. We study the collision of plasma slabs of different density, leading to two different shocks and a contact discontinuity. Electron dynamics play an important role in the development of the system. While non-relativistic shocks in both unmagnetized and magnetized plasmas can be mediated by Weibel-type instabilities, the efficiency of shock-formation processes is higher when a large-scale magnetic field is present. The electron distributions downstream of the forward and reverse shocks are generally isotropic, whereas that is not always the case for the ions. We do not see any significant evidence of pre-acceleration, neither in the electron population nor in the ion distribution.
The Gaussian entropy of fermionic systems
Energy Technology Data Exchange (ETDEWEB)
Prokopec, Tomislav, E-mail: T.Prokopec@uu.nl [Institute for Theoretical Physics (ITP) and Spinoza Institute, Utrecht University, Postbus 80195, 3508 TD Utrecht (Netherlands); Schmidt, Michael G., E-mail: M.G.Schmidt@thphys.uni-heidelberg.de [Institut fuer Theoretische Physik, Heidelberg University, Philosophenweg 16, D-69120 Heidelberg (Germany); Weenink, Jan, E-mail: J.G.Weenink@uu.nl [Institute for Theoretical Physics (ITP) and Spinoza Institute, Utrecht University, Postbus 80195, 3508 TD Utrecht (Netherlands)
2012-12-15
We consider the entropy and decoherence in fermionic quantum systems. By making a Gaussian Ansatz for the density operator of a collection of fermions we study statistical 2-point correlators and express the entropy of a system fermion in terms of these correlators. In a simple case when a set of N thermalised environmental fermionic oscillators interacts bi-linearly with the system fermion we can study its time dependent entropy, which also represents a quantitative measure for decoherence and classicalization. We then consider a relativistic fermionic quantum field theory and take a mass mixing term as a simple model for the Yukawa interaction. It turns out that even in this Gaussian approximation, the fermionic system decoheres quite effectively, such that in a large coupling and high temperature regime the system field approaches the temperature of the environmental fields. - Highlights: Black-Right-Pointing-Pointer We construct the Gaussian density operator for relativistic fermionic systems. Black-Right-Pointing-Pointer The Gaussian entropy of relativistic fermionic systems is described in terms of 2-point correlators. Black-Right-Pointing-Pointer We explicitly show the growth of entropy for fermionic fields mixing with a thermal fermionic environment.
One-parameter nonrelativistic supersymmetry for microtubules
Rosu, H C
2003-01-01
The simple supersymmetric model of Caticha [PRA 51, 4264 (1995)], as used by Rosu [PRE 55, 2038 (1997)] for microtubules, is generalized to the case of Mielnik's one-parameter nonrelativistic susy [JMP 25, 3387 (1984)
Curved non-relativistic spacetimes, Newtonian gravitation and massive matter
Energy Technology Data Exchange (ETDEWEB)
Geracie, Michael, E-mail: mgeracie@uchicago.edu; Prabhu, Kartik, E-mail: kartikp@uchicago.edu; Roberts, Matthew M., E-mail: matthewroberts@uchicago.edu [Kadanoff Center for Theoretical Physics, Enrico Fermi Institute and Department of Physics, The University of Chicago, Chicago, Illinois 60637 (United States)
2015-10-15
There is significant recent work on coupling matter to Newton-Cartan spacetimes with the aim of investigating certain condensed matter phenomena. To this end, one needs to have a completely general spacetime consistent with local non-relativistic symmetries which supports massive matter fields. In particular, one cannot impose a priori restrictions on the geometric data if one wants to analyze matter response to a perturbed geometry. In this paper, we construct such a Bargmann spacetime in complete generality without any prior restrictions on the fields specifying the geometry. The resulting spacetime structure includes the familiar Newton-Cartan structure with an additional gauge field which couples to mass. We illustrate the matter coupling with a few examples. The general spacetime we construct also includes as a special case the covariant description of Newtonian gravity, which has been thoroughly investigated in previous works. We also show how our Bargmann spacetimes arise from a suitable non-relativistic limit of Lorentzian spacetimes. In a companion paper [M. Geracie et al., e-print http://arxiv.org/abs/1503.02680 ], we use this Bargmann spacetime structure to investigate the details of matter couplings, including the Noether-Ward identities, and transport phenomena and thermodynamics of non-relativistic fluids.
Zadeh, S Rostam
2015-01-01
We study simultaneous evolution of fermion asymmetries and large scale hypermagnetic fields in the symmetric phase of the electroweak plasma in the temperature range $100$GeV$\\leq T\\leq 10$TeV, taking into account the chirality flip processes via Higgs inverse decays and fermion number violation due to Abelian anomalies for electrons, neutrinos and quarks in the presence of hypermagnetic fields. We present a derivation of the coefficient of the Chern-Simons term for the hypercharge gauge field, showing that the left-handed and right-handed components of each fermion species contribute with opposite sign. This is in contrast to the results presented in some of the previous works. The Chern-Simons term affects the resulting anomalous magnetohydrodynamic (AMHD) equations. We solve the resulting coupled evolution equations for the lepton and baryon asymmetries, as well as the hypermagnetic field to obtain their time evolution along with their values at the electroweak phase transition ($T_{EW} \\sim 100$GeV) for a...
Electron Scattering from Freely Moveable spin-$\\frac{1}{2}$ fermion in Strong Laser Field
Liu, Ai-Hua
2014-01-01
We study the electron scatter from the freely movable spin-$\\frac{1}{2}$ particle in the presence of a linearly polarized laser field in the first Born approximation. The dressed state of electrons is described by a time-dependent wave function derived from a perturbation treatment (of the laser field). With the aid of numerical results we explore the dependencies of the differential cross section on the laser field properties such as the strength, the frequency, as well as on the electron-impact energy, etc. Due to the targets are movable, the DCS of this process reduced comparing to the Mott scattering, especially in small scattering angles.
Vitali, Ettore; Shi, Hao; Qin, Mingpu; Zhang, Shiwei
2016-08-01
We address the calculation of dynamical correlation functions for many fermion systems at zero temperature, using the auxiliary-field quantum Monte Carlo method. The two-dimensional Hubbard hamiltonian is used as a model system. Although most of the calculations performed here are for cases where the sign problem is absent, the discussions are kept general for applications to physical problems when the sign problem does arise. We study the use of twisted boundary conditions to improve the extrapolation of the results to the thermodynamic limit. A strategy is proposed to drastically reduce finite size effects relying on a minimization among the twist angles. This approach is demonstrated by computing the charge gap at half filling. We obtain accurate results showing the scaling of the gap with the interaction strength U in two dimensions, connecting to the scaling of the unrestricted Hartree-Fock method at small U and Bethe ansatz exact result in one dimension at large U . An alternative algorithm is then proposed to compute dynamical Green functions and correlation functions which explicitly varies the number of particles during the random walks in the manifold of Slater determinants. In dilute systems, such as ultracold Fermi gases, this algorithm enables calculations with much more favorable complexity, with computational cost proportional to basis size or the number of lattice sites.
A simplified BBGKY hierarchy for correlated fermionic systems from a Stochastic Mean-Field approach
Lacroix, Denis; Ayik, Sakir; Yilmaz, Bulent
2015-01-01
The stochastic mean-field (SMF) approach allows to treat correlations beyond mean-field using a set of independent mean-field trajectories with appropriate choice of fluctuating initial conditions. We show here, that this approach is equivalent to a simplified version of the Bogolyubov-Born-Green-Kirkwood-Yvon (BBGKY) hierarchy between one-, two-, ..., N-body degrees of freedom. In this simplified version, one-body degrees of freedom are coupled to fluctuations to all orders while retaining only specific terms of the general BBGKY hierarchy. The use of the simplified BBGKY is illustrated with the Lipkin-Meshkov-Glick (LMG) model. We show that a truncated version of this hierarchy can be useful, as an alternative to the SMF, especially in the weak coupling regime to get physical insight in the effect beyond mean-field. In particular, it leads to approximate analytical expressions for the quantum fluctuations both in the weak and strong coupling regime. In the strong coupling regime, it can only be used for sho...
A simplified BBGKY hierarchy for correlated fermions from a stochastic mean-field approach
Energy Technology Data Exchange (ETDEWEB)
Lacroix, Denis; Tanimura, Yusuke [Universite Paris-Sud, Institut de Physique Nucleaire, IN2P3-CNRS, Orsay (France); Ayik, Sakir [Tennessee Technological University, Physics Department, Cookeville, TN (United States); Yilmaz, Bulent [Ankara University, Physics Department, Faculty of Sciences, Ankara (Turkey)
2016-04-15
The stochastic mean-field (SMF) approach allows to treat correlations beyond mean-field using a set of independent mean-field trajectories with appropriate choice of fluctuating initial conditions. We show here that this approach is equivalent to a simplified version of the Bogolyubov-Born-Green-Kirkwood-Yvon (BBGKY) hierarchy between one-, two-,.., N -body degrees of freedom. In this simplified version, one-body degrees of freedom are coupled to fluctuations to all orders while retaining only specific terms of the general BBGKY hierarchy. The use of the simplified BBGKY is illustrated with the Lipkin-Meshkov-Glick (LMG) model. We show that a truncated version of this hierarchy can be useful, as an alternative to the SMF, especially in the weak coupling regime to get physical insight in the effect beyond mean-field. In particular, it leads to approximate analytical expressions for the quantum fluctuations both in the weak and strong coupling regime. In the strong coupling regime, it can only be used for short time evolution. In that case, it gives information on the evolution time-scale close to a saddle point associated to a quantum phase-transition. For long time evolution and strong coupling, we observed that the simplified BBGKY hierarchy cannot be truncated and only the full SMF with initial sampling leads to reasonable results. (orig.)
Phase transition of a heavy-fermion superconductor in a high magnetic field: Entanglement analysis
Afzali, R.; Ebrahimian, N.
2013-08-01
When the magnetic field is only acting on the spin of electrons, a transition from a normal to a modulated superconducting state or Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconducting state may occur at low temperatures. A FFLO superconducting state, which accompanies an order parameter that oscillates spatially, may be stabilized by a high applied magnetic field or a molecular field. Quantum multipartite entanglement is a new procedure for investigating quantum phase transitions. In this article, we deal with the phase transition of the FFLO state of CeCoIn5 to a normal state by obtaining quantum multipartite entanglement of the system. For this purpose, using normal and anomalous Green functions and the density matrix, we obtain concurrence, as a measure of bipartite entanglement. Then, the order parameter and the magnetic -field dependence of multipartite entanglement in momentum space is calculated. The phase transition is determined, and the behavior of the system based on order parameter is discussed. Furthermore, the phase transitions of both the Bardeen-Cooper-Schrieffer (BCS) and FFLO states to the normal state are compared.
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
Wang, Zhijun; Alexandradinata, A.; Cava, Robert J.; Bernevig, B. Andrei
Spatial symmetries in crystals are distinguished by whether they preserve the spatial origin. We show how this basic geometric property gives rise to a new topology in band insulators. We study spatial symmetries that translate the origin by a fraction of the lattice period, and find that these nonsymmorphic symmetries protect a novel surface fermion whose dispersion is shaped like an hourglass; surface bands connect one hourglass to the next in an unbreakable zigzag pattern. These exotic fermions are materialized in the large-gap insulators: KHg X (X = As,Sb,Bi), which we propose as the first material class whose topology relies on nonsymmorphic symmetries. Beside the hourglass fermion, a different surface of KHg X manifests a 3D generalization of the quantum spin Hall effect. To describe the bulk topology of nonsymmorphic crystals, we propose a non-Abelian generalization of the geometric theory of polarization. Our nontrivial topology originates not from an inversion of the parity quantum numbers, but rather of the rotational quantum numbers, which we propose as a fruitful in the search for topological materials. Finally, KHg X uniquely exemplifies a cohomological insulator, a concept that we will introduce in a companion work.
Cortés, J. L.; López-Sarrión, Justo
2017-05-01
In this paper, we study the consistency of having Lorentz invariance as a low energy approximation within the quantum field theory framework. A model with a scalar and a fermion field is used to show how a Lorentz invariance violating high momentum scale, a physical cutoff rendering the quantum field theory finite, can be made compatible with a suppression of Lorentz invariance violations at low momenta. The fine tuning required to get this suppression and to have a light scalar particle in the spectrum are determined at one loop.
Dirac fermions in strong electric field and quantum transport in graphene
Gavrilov, S P; Yokomizo, N
2012-01-01
Our previous results on the nonperturbative calculations of the mean current and of the energy-momentum tensor in QED with the T-constant electric field are generalized to arbitrary dimensions. The renormalized mean values are found; the vacuum polarization and particle creation contributions to these mean values are isolated in the large T-limit, the vacuum polarization contributions being related to the one-loop effective Euler-Heisenberg Lagrangian. Peculiarities in odd dimensions are considered in detail. We adapt general results obtained in 2+1 dimensions to the conditions which are realized in the Dirac model for graphene. We study the quantum electronic and energy transport in the graphene at low carrier density and low temperatures when quantum interference effects are important. Our description of the quantum transport in the graphene is based on the so-called generalized Furry picture in QED where the strong external field is taken into account nonperturbatively; this approach is not restricted to a...
Fermions as generalized Ising models
Wetterich, C.
2017-04-01
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.
Symmetries and couplings of non-relativistic electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Festuccia, Guido [Department of Physics and Astronomy, Uppsala University,Lägerhyddsvägen 1, Uppsala (Sweden); Hansen, Dennis [The Niels Bohr Institute, Copenhagen University,Blegdamsvej 17, Copenhagen Ø, DK-2100 (Denmark); Hartong, Jelle [Physique Théorique et Mathématique and International Solvay Institutes,Université Libre de Bruxelles, C.P. 231, Brussels, 1050 (Belgium); Obers, Niels A. [The Niels Bohr Institute, Copenhagen University,Blegdamsvej 17, Copenhagen Ø, DK-2100 (Denmark)
2016-11-08
We examine three versions of non-relativistic electrodynamics, known as the electric and magnetic limit theories of Maxwell’s equations and Galilean electrodynamics (GED) which is the off-shell non-relativistic limit of Maxwell plus a free scalar field. For each of these three cases we study the couplings to non-relativistic dynamical charged matter (point particles and charged complex scalars). The GED theory contains besides the electric and magnetic potentials a so-called mass potential making the mass parameter a local function. The electric and magnetic limit theories can be coupled to twistless torsional Newton-Cartan geometry while GED can be coupled to an arbitrary torsional Newton-Cartan background. The global symmetries of the electric and magnetic limit theories on flat space consist in any dimension of the infinite dimensional Galilean conformal algebra and a U(1) current algebra. For the on-shell GED theory this symmetry is reduced but still infinite dimensional, while off-shell only the Galilei algebra plus two dilatations remain. Hence one can scale time and space independently, allowing Lifshitz scale symmetries for any value of the critical exponent z.
Symmetries and Couplings of Non-Relativistic Electrodynamics
Festuccia, Guido; Hartong, Jelle; Obers, Niels A
2016-01-01
We examine three versions of non-relativistic electrodynamics, known as the electric and magnetic limit theories of Maxwell's equations and Galilean electrodynamics (GED) which is the off-shell non-relativistic limit of Maxwell plus a free scalar field. For each of these three cases we study the couplings to non-relativistic dynamical charged matter (point particles and charged complex scalars). The GED theory contains besides the electric and magnetic potentials a so-called mass potential making the mass parameter a local function. The electric and magnetic limit theories can be coupled to twistless torsional Newton-Cartan geometry while GED can be coupled to an arbitrary torsional Newton-Cartan background. The global symmetries of the electric and magnetic limit theories on flat space consist in any dimension of the infinite dimensional Galilean conformal algebra and a $U(1)$ current algebra. For the on-shell GED theory this symmetry is reduced but still infinite dimensional, while off-shell only the Galile...
Beyond-mean-field boson-fermion model for odd-mass nuclei
Nomura, K.; Nikšić, T.; Vretenar, D.
2016-05-01
A novel method for calculating spectroscopic properties of medium-mass and heavy atomic nuclei with an odd number of nucleons is introduced, based on the framework of nuclear energy density functional theory and the particle-core coupling scheme. The deformation energy surface of the even-even core, as well as the spherical single-particle energies and occupation probabilities of the odd particle(s), are obtained in a self-consistent mean-field calculation determined by the choice of the energy density functional and pairing interaction. This method uniquely determines the parameters of the Hamiltonian of the boson core, and only the strength of the particle-core coupling is specifically adjusted to selected data for a particular nucleus. The approach is illustrated in a systematic study of low-energy excitation spectra and transition rates of axially deformed odd-mass Eu isotopes.
Beyond mean-field boson-fermion model for odd-mass nuclei
Nomura, K; Vretenar, D
2016-01-01
A novel method for calculating spectroscopic properties of medium-mass and heavy atomic nuclei with an odd number of nucleons is introduced, based on the framework of nuclear energy density functional theory and the particle-core coupling scheme. The deformation energy surface of the even-even core, as well as the spherical single-particle energies and occupation probabilities of the odd particle(s), are obtained in a self-consistent mean-field calculation determined by the choice of the energy density functional and pairing interaction. This method uniquely determines the parameters of the Hamiltonian of the boson core, and only the strength of the particle-core coupling is specifically adjusted to selected data for a particular nucleus. The approach is illustrated in a systematic study of low-energy excitation spectra and transition rates of axially deformed odd-mass Eu isotopes.
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.
Banerjee, D; Dalmonte, M; Müller, M; Rico, E; Stebler, P; Wiese, U-J; Zoller, P
2012-10-26
Using a Fermi-Bose mixture of ultracold atoms in an optical lattice, we construct a quantum simulator for a U(1) gauge theory coupled to fermionic matter. The construction is based on quantum links which realize continuous gauge symmetry with discrete quantum variables. At low energies, quantum link models with staggered fermions emerge from a Hubbard-type model which can be quantum simulated. This allows us to investigate string breaking as well as the real-time evolution after a quench in gauge theories, which are inaccessible to classical simulation methods.
Banerjee D.; Dalmonte M.; Muller M; Rico E.; Stebler P.; Wiese U.-J.; Zoller P.
2012-01-01
Using a Fermi-Bose mixture of ultra-cold atoms in an optical lattice, we construct a quantum simulator for a U(1) gauge theory coupled to fermionic matter. The construction is based on quantum links which realize continuous gauge symmetry with discrete quantum variables. At low energies, quantum link models with staggered fermions emerge from a Hubbard-type model which can be quantum simulated. This allows us to investigate string breaking as well as the real-time evolution after a quench in ...
Integrable Gross-Neveu models with fermion-fermion and fermion-antifermion pairing
Thies, Michael
2014-01-01
The massless Gross-Neveu and chiral Gross-Neveu models are well known examples of integrable quantum field theories in 1+1 dimensions. We address the question whether integrability is preserved if one either replaces the four-fermion interaction in fermion-antifermion channels by a dual interaction in fermion-fermion channels, or if one adds such a dual interaction to an existing integrable model. The relativistic Hartree-Fock-Bogoliubov approach is adequate to deal with the large N limit of such models. In this way, we construct and solve three integrable models with Cooper pairing. We also identify a candidate for a fourth integrable model with maximal kinematic symmetry, the "perfect" Gross-Neveu model. This type of field theories can serve as exactly solvable toy models for color superconductivity in quantum chromodynamics.
Non-relativistic Bondi–Metzner–Sachs algebra
Batlle, Carles; Delmastro, Diego; Gomis, Joaquim
2017-09-01
We construct two possible candidates for non-relativistic bms4 algebra in four space-time dimensions by contracting the original relativistic bms4 algebra. bms4 algebra is infinite-dimensional and it contains the generators of the Poincaré algebra, together with the so-called super-translations. Similarly, the proposed nrbms4 algebras can be regarded as two infinite-dimensional extensions of the Bargmann algebra. We also study a canonical realization of one of these algebras in terms of the Fourier modes of a free Schrödinger field, mimicking the canonical realization of relativistic bms4 algebra using a free Klein–Gordon field.
Adler, Stephen L
2016-01-01
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 [1] we proposed earlier. 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 producing hierarchies, and for generating the standard model fermions as composites formed from the original $SU(8)$ model fermions, which play the role of "preons". Quarks can emerge 5 preon composites and leptons as 3 preon composites, with consequent stability of the proton against decay to a single lepton plus mesons.
Holographic fermionic spectrum from Born–Infeld AdS black hole
Energy Technology Data Exchange (ETDEWEB)
Wu, Jian-Pin, E-mail: jianpinwu@mail.bnu.edu.cn [Institute of Gravitation and Cosmology, Department of Physics, School of Mathematics and Physics, Bohai University, Jinzhou 121013 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai, 200444 (China)
2016-07-10
In this letter, we systematically explore the holographic (non-)relativistic fermionic spectrum without/with dipole coupling dual to Born–Infeld anti-de Sitter (BI-AdS) black hole. For the relativistic fermionic fixed point, this holographic fermionic system exhibits non-Fermi liquid behavior. Also, with the increase of BI parameter γ, the non-Fermi liquid becomes even “more non-Fermi”. When the dipole coupling term is included, we find that the BI term makes it a lot tougher to form the gap. While for the non-relativistic fermionic system with large dipole coupling in BI-AdS background, with the increase of BI parameter, the gap comes into being again.
Holographic fermionic spectrum from Born-Infeld AdS black hole
Wu, Jian-Pin
2016-07-01
In this letter, we systematically explore the holographic (non-)relativistic fermionic spectrum without/with dipole coupling dual to Born-Infeld anti-de Sitter (BI-AdS) black hole. For the relativistic fermionic fixed point, this holographic fermionic system exhibits non-Fermi liquid behavior. Also, with the increase of BI parameter γ, the non-Fermi liquid becomes even ;more non-Fermi;. When the dipole coupling term is included, we find that the BI term makes it a lot tougher to form the gap. While for the non-relativistic fermionic system with large dipole coupling in BI-AdS background, with the increase of BI parameter, the gap comes into being again.
Holographic fermionic spectrum from Born–Infeld AdS black hole
Directory of Open Access Journals (Sweden)
Jian-Pin Wu
2016-07-01
Full Text Available In this letter, we systematically explore the holographic (non-relativistic fermionic spectrum without/with dipole coupling dual to Born–Infeld anti-de Sitter (BI-AdS black hole. For the relativistic fermionic fixed point, this holographic fermionic system exhibits non-Fermi liquid behavior. Also, with the increase of BI parameter γ, the non-Fermi liquid becomes even “more non-Fermi”. When the dipole coupling term is included, we find that the BI term makes it a lot tougher to form the gap. While for the non-relativistic fermionic system with large dipole coupling in BI-AdS background, with the increase of BI parameter, the gap comes into being again.
Noninertial effects on nonrelativistic topological quantum scattering
Mota, H. F.; Bakke, K.
2017-08-01
We investigate noninertial effects on the scattering problem of a nonrelativistic particle in the cosmic string spacetime. By considering the nonrelativistic limit of the Dirac equation we are able to show, in the regime of small rotational frequencies, that the phase shift has two contribution: one related to the noninertial reference frame, and the other, due to the cosmic string conical topology. We also show that both the incident wave and the scattering amplitude are altered as a consequence of the noninertial reference frame and depend on the rotational frequency.
Sarkar, Sujit
2014-01-01
Quantum simulation aims to simulate a quantum system using a controble laboratory system that underline the same mathematical model. Cavity QED lattice system is that prescribe system to simulate the relativistic quantum effect. We quantum simulate the Dirac fermion mode, Majorana fermion mode and Majorana-Weyl fermion mode and a crossover between them in cavity QED lattice. We also present the different analytical relations between the field operators for different mode excitations.
Fermion RG blocking transformations and IR structure
Cheng, X
2011-01-01
We explore fermion RG block-spinning transformations on the lattice with the aim of studying the IR structure of gauge theories and, in particular, the existence of IR fixed points for varying fermion content. In the case of light fermions the main concern and difficulty is ensuring locality of any adopted blocking scheme. We discuss the problem of constructing a local blocked fermion action in the background of arbitrary gauge fields. We then discuss the carrying out of accompanying gauge field blocking. In the presence of the blocked fermions implementation of MCRG is not straightforward. By adopting judicious approximations we arrive at an easily implementable approximate RG recursion scheme that allows quick, inexpensive estimates of the location of conformal windows for various groups and fermion representations. We apply this scheme to locate the conformal windows in the case of SU(2) and SU(3) gauge groups. Some of the reasons for the apparent efficacy of this and similar decimation schemes are discuss...
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...
Chiral scars in chaotic Dirac fermion systems.
Xu, Hongya; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso
2013-02-08
Do relativistic quantum scars in classically chaotic systems possess unique features that are not shared by nonrelativistic quantum scars? We report a class of relativistic quantum scars in massless Dirac fermion systems whose phases return to the original values or acquire a 2π change only after circulating twice about some classical unstable periodic orbits. We name such scars chiral scars, the successful identification of which has been facilitated tremendously by our development of an analytic, conformal-mapping-based method to calculate an unprecedentedly large number of eigenstates with high accuracy. Our semiclassical theory indicates that the physical origin of chiral scars can be attributed to a combined effect of chirality intrinsic to massless Dirac fermions and the geometry of the underlying classical orbit.
Perfect Lattice Actions for Staggered Fermions
Bietenholz, W; Chandrasekharan, S; Wiese, U J
1996-01-01
We construct a perfect lattice action for staggered fermions by blocking from the continuum. The locality, spectrum and pressure of such perfect staggered fermions are discussed. We also derive a consistent fixed point action for free gauge fields and discuss its locality as well as the resulting static quark-antiquark potential. This provides a basis for the construction of (classically) perfect lattice actions for QCD using staggered fermions.
Spin & Statistics in Nonrelativistic Quantum Mechanics, II
Kuckert, B; Kuckert, Bernd; Mund, Jens
2004-01-01
Recently a sufficient and necessary condition for Pauli's spin- statistics connection in nonrelativistic quantum mechanics has been established [quant-ph/0208151]. The two-dimensional part of this result is extended to n-particle systems and reformulated and further simplified in a more geometric language.
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...
From Gauging Nonrelativistic Translations to N-Body Dynamics
Lukierski, J; Zakrzewski, W J
2001-01-01
We consider the gauging of space translations with time-dependent gauge functions. Using fixed time gauge of relativistic theory, we consider the gauge-invariant model describing the motion of nonrelativistic particles. When we use gauge-invariant nonrelativistic velocities as independent variables the translation gauge fields enter the equations through a d\\times (d+1) matrix of vielbein fields and their Abelian field strengths, which can be identified with the torsion tensors of teleparallel formulation of relativity theory. We consider the planar case (d=2) in some detail, with the assumption that the action for the dreibein fields is given by the translational Chern-Simons term. We fix the asymptotic transformations in such a way that the space part of the metric becomes asymptotically Euclidean. The residual symmetries are (local in time) translations and rigid rotations. We describe the effective interaction of the d=2 N-particle problem and discuss its classical solution for N=2. The phase space Hamilt...
Lattice Chiral Fermions Through Gauge Fixing
Bock, W; Shamir, Y; Bock, Wolfgang; Golterman, Maarten; Shamir, Yigal
1998-01-01
We study a concrete lattice regularization of a U(1) chiral gauge theory. We use Wilson fermions, and include a Lorentz gauge-fixing term and a gauge-boson mass counterterm. For a reduced version of the model, in which the gauge fields are constrained to the trivial orbit, we show that there are no species doublers, and that the fermion spectrum contains only the desired states in the continuum limit, namely charged left-handed (LH) fermions and neutral right-handed (RH) fermions.
Shaginyan, V. R.; Msezane, A. Z.; Popov, K. G.; Clark, J. W.; Khodel, V. A.; Zverev, M. V.
2016-05-01
Informative recent measurements on the heavy-fermion metal β -YbAlB4 performed with applied magnetic field and pressure as control parameters are analyzed with the goal of establishing a sound theoretical explanation for the inferred scaling laws and non-Fermi-liquid (NFL) behavior, which demonstrate some unexpected features. Most notably, the robustness of the NFL behavior of the thermodynamic properties and of the anomalous T3 /2 temperature dependence of the electrical resistivity under applied pressure P in zero magnetic field is at variance with the fragility of the NFL phase under application of a field B . We show that a consistent topological basis for this combination of observations, as well as the empirical scaling laws, may be found within fermion-condensation theory in the emergence and destruction of a flat band, and explains that the paramagnetic NFL phase takes place without magnetic criticality, not from quantum critical fluctuations. Schematic T -B and T -P phase diagrams are presented to illuminate this scenario.
Unitary fermions on the lattice I: in a harmonic trap
Endres, Michael G; Lee, Jong-Wan; Nicholson, Amy N
2011-01-01
We present a new lattice Monte Carlo approach developed for studying large numbers of strongly interacting nonrelativistic fermions, and apply it to a dilute gas of unitary fermions confined to a harmonic trap. Our lattice action is highly improved, with sources of discretization and finite volume errors systematically removed; we are able to demonstrate the expected volume scaling of energy levels of two and three untrapped fermions, and to reproduce the high precision calculations published previously for the ground state energies for N = 3 unitary fermions in a box (to within our 0.3% uncertainty), and for N = 3, . . ., 6 unitary fermions in a harmonic trap (to within our ~ 1% uncertainty). We use this action to determine the ground state energies of up to 70 unpolarized fermions trapped in a harmonic potential on a lattice as large as 64^3 x 72; our approach avoids the use of importance sampling or calculation of a fermion determinant and employs a novel statistical method for estimating observables, allo...
Quantum field theory from classical statistics
Wetterich, C
2011-01-01
An Ising-type classical statistical model is shown to describe quantum fermions. For a suitable time-evolution law for the probability distribution of the Ising-spins our model describes a quantum field theory for Dirac spinors in external electromagnetic fields, corresponding to a mean field approximation to quantum electrodynamics. All quantum features for the motion of an arbitrary number of electrons and positrons, including the characteristic interference effects for two-fermion states, are described by the classical statistical model. For one-particle states in the non-relativistic approximation we derive the Schr\\"odinger equation for a particle in a potential from the time evolution law for the probability distribution of the Ising-spins. Thus all characteristic quantum features, as interference in a double slit experiment, tunneling or discrete energy levels for stationary states, are derived from a classical statistical ensemble. Concerning the particle-wave-duality of quantum mechanics, the discret...
Acoustoelectric current for composite fermions
Bergli, J.; Galperin, Y. M.
2001-07-01
The acoustoelectric current for composite fermions in a two-dimensional electron gas (2DEG) close to the half-filled Landau level is calculated in the random phase approximation. The Boltzmann equation is used to find the nonequilibrium distribution of composite fermions to second order in the acoustic field. It is shown that the oscillating Chern-Simons field created by the induced density fluctuations in the 2DEG is important for the acoustoelectric current. This leads to a violation of the Weinreich relation between the acoustoelectric current and acoustic intensity. The deviations from the Weinreich relation can be detected by measuring the angle between the longitudinal and the Hall components of the acoustoelectric current. This departure from the Weinreich relation gives additional information on the properties of the composite fermion fluid.
Effective Lagrangian for Nonrelativistic Systems
Directory of Open Access Journals (Sweden)
Haruki Watanabe
2014-09-01
Full Text Available The effective Lagrangian for Nambu-Goldstone bosons (NGBs in systems without Lorentz invariance has a novel feature that some of the NGBs are canonically conjugate to each other, hence describing 1 dynamical degree of freedom by two NGB fields. We develop explicit forms of their effective Lagrangian up to the quadratic order in derivatives. We clarify the counting rules of NGB degrees of freedom and completely classify possibilities of such canonically conjugate pairs based on the topology of the coset spaces. Its consequence on the dispersion relations of the NGBs is clarified. We also present simple scaling arguments to see whether interactions among NGBs are marginal or irrelevant, which justifies a lore in the literature about the possibility of symmetry breaking in 1+1 dimensions.
Relativistic Remnants of Non-Relativistic Electrons
Kashiwa, Taro
2015-01-01
Electrons obeying the Dirac equation are investigated under the non-relativistic $c \\mapsto \\infty$ limit. General solutions are given by derivatives of the relativistic invariant functions whose forms are different in the time- and the space-like region, yielding the delta function of $(ct)^2 - x^2$. This light-cone singularity does survive to show that the charge and the current density of electrons travel with the speed of light in spite of their massiveness.
Supersymmetric solutions for non-relativistic holography
Energy Technology Data Exchange (ETDEWEB)
Donos, Aristomenis [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gauntlett, Jerome P. [Blackett Laboratory, Imperial College, London (United Kingdom)]|[Institute for Mathematical Sciences, Imperial College, London (United Kingdom)
2009-01-15
We construct families of supersymmetric solutions of type IIB and D=11 supergravity that are invariant under the non-relativistic conformal algebra for various values of dynamical exponent z{>=}4 and z{>=}3, respectively. The solutions are based on five- and seven-dimensional Sasaki-Einstein manifolds and generalise the known solutions with dynamical exponent z=4 for the type IIB case and z=3 for the D=11 case, respectively. (orig.)
Liu, Jianbin; Zheng, Huaibin; Chen, Hui; Li, Fu-li; Xu, Zhuo
2016-01-01
Ghost imaging with thermal fermions is calculated based on two-particle interference in Feynman's path integral theory. It is found that ghost imaging with thermal fermions can be simulated by ghost imaging with thermal bosons and classical particles. Photons in pseudothermal light are employed to experimentally study fermionic ghost imaging. Ghost imaging with thermal bosons and fermions is discussed based on the point-to-point (spot) correlation between the object and image planes. The employed method offers an efficient guidance for future ghost imaging with real thermal fermions, which may also be generalized to study other second-order interference phenomena with fermions.
Differential Regularization of a Non-relativistic Anyon Model
Freedman, Daniel Z; Rius, N
1994-01-01
Differential regularization is applied to a field theory of a non-relativistic charged boson field $\\phi$ with $\\lambda (\\phi {}^{*} \\phi)^2$ self-interaction and coupling to a statistics-changing $U(1)$ Chern-Simons gauge field. Renormalized configuration-space amplitudes for all diagrams contributing to the $\\phi {}^{*} \\phi {}^{*} \\phi \\phi$ 4-point function, which is the only primitively divergent Green's function, are obtained up to 3-loop order. The renormalization group equations are explicitly checked, and the scheme dependence of the $\\beta$-function is investigated. If the renormalization scheme is fixed to agree with a previous 1-loop calculation, the 2- and 3-loop contributions to $\\beta(\\lambda,e)$ vanish, and $\\beta(\\lambda,e)$ itself vanishes when the ``self-dual'' condition relating $\\lambda$ to the gauge coupling $e$ is imposed.
Energy Technology Data Exchange (ETDEWEB)
Sahu, Biswajit, E-mail: biswajit-sahu@yahoo.co.in [Department of Mathematics, West Bengal State University, Barasat, Kolkata 700126 (India); Sinha, Anjana, E-mail: sinha.anjana@gmail.com [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India); Roychoudhury, Rajkumar, E-mail: rroychoudhury123@gmail.com [Department of Mathematics, Visva-Bharati, Santiniketan - 731 204, India and Advanced Centre for Nonlinear and Complex Phenomena, 1175 Survey Park, Kolkata 700 075 (India)
2015-09-15
A numerical study is presented of the nonlinear dynamics of a magnetized, cold, non-relativistic plasma, in the presence of electron-ion collisions. The ions are considered to be immobile while the electrons move with non-relativistic velocities. The primary interest is to study the effects of the collision parameter, external magnetic field strength, and the initial electromagnetic polarization on the evolution of the plasma system.
Physical stress, mass, and energy for non-relativistic spinful matter
Geracie, Michael; Roberts, Matthew M
2016-01-01
For theories of relativistic matter fields with spin there exist two possible definitions of the stress-energy tensor, one defined by a variation of the action with the coframes at fixed connection, and the other at fixed torsion. These two stress-energy tensors do not necessarily coincide and it is the latter that corresponds to the Cauchy stress measured in the lab. In this note we discuss the corresponding issue for non-relativistic matter theories. We point out that while the physical non-relativistic stress, momentum, and mass currents are defined by a variation of the action at fixed torsion, the energy current does not admit such a description and is naturally defined at fixed connection. Any attempt to define an energy current at fixed torsion results in an ambiguity which cannot be resolved from the background spacetime data or conservation laws. We also provide computations of these quantities for some simple non-relativistic actions.
Fermions in Brans-Dicke cosmology
Samojeden, L L; Kremer, G M
2010-01-01
Using the Brans-Dicke theory of gravitation we put under investigation a hypothetical universe filled with a fermionic field (with a self interaction potential) and a matter constituent ruled by a barotropic equation of state. It is shown that the fermionic field (in combination with the Brans-Dicke scalar field could be responsible for a final accelerated era, after an initial matter dominated period.
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.
Light Front Fermion Model Propagation
Institute of Scientific and Technical Information of China (English)
Jorge Henrique Sales; Alfredo Takashi Suzuki
2013-01-01
In this work we consider the propagation of two fermion fields interacting with each other by the exchange of intermediate scalar bosons in the light front.We obtain the corrections up to fourth order in the coupling constant using hierarchical equations in order to obtain the bound state equation (Bethe-Salpeter equation).
Gravitational contribution to fermion masses
Tiemblo, A; Tiemblo, Alfredo; Tresguerres, Romualdo
2005-01-01
In the context of a nonlinear gauge theory of the Poincar\\'e group, we show that covariant derivatives of Dirac fields include a coupling to the translational connections, manifesting itself in the matter action as a universal background mass contribution to fermions.
Levi, T; Levi, Thomas s.; Gleiser, Marcelo
2002-01-01
We present a new model for a non-topological soliton (NTS) that contains fermions, scalar particles and a gauge field. Using a variational approach, we estimate the energy of the localized configuration, showing that it can be the lowest energy state of the system for a wide range of parameters.
Gravitational contribution to fermion masses
Tiemblo, Alfredo; Tresguerres, Romualdo
2005-01-01
In the context of a nonlinear gauge theory of the Poincar\\'e group, we show that covariant derivatives of Dirac fields include a coupling to the translational connections, manifesting itself in the matter action as a universal background mass contribution to fermions.
Gravitational contribution to fermion masses
Energy Technology Data Exchange (ETDEWEB)
Tiemblo, A.; Tresguerres, R. [Consejo Superior de Investigaciones Cientificas, Instituto de Matematicas y Fisica Fundamental, Madrid (Spain)
2005-08-01
In the context of a non-linear gauge theory of the Poincare group, we show that covariant derivatives of Dirac fields include a coupling to the translational connections, manifesting itself in the matter action as a universal background mass contribution to fermions. (orig.)
Espin, Johnny
2015-01-01
It has been proposed several times in the past that one can obtain an equivalent, but in many aspects simpler description of fermions by first reformulating their first-order (Dirac) Lagrangian in terms of two-component spinors, and then integrating out the spinors of one chirality ($e.g.$ primed or dotted). The resulting new Lagrangian is second-order in derivatives, and contains two-component spinors of only one chirality. The new second-order formulation simplifies the fermion Feynman rules of the theory considerably, $e.g.$ the propagator becomes a multiple of an identity matrix in the field space. The aim of this thesis is to work out the details of this formulation for theories such as Quantum Electrodynamics, and the Standard Model of elementary particles. After having developed the tools necessary to establish the second-order formalism as an equivalent approach to spinor field theories, we proceed with some important consistency checks that the new formulation is required to pass, namely the presence...
Fermionic T-duality: A snapshot review
Colgáin, Eoin Ó
2012-01-01
Through a self-dual mapping of the geometry AdS5 x S5, fermionic T-duality provides a beautiful geometric interpretation of hidden symmetries for scattering amplitudes in N=4 super-Yang-Mills. Starting with Green-Schwarz sigma-models, we consolidate developments in this area into this small review. In particular, we discuss the translation of fermionic T-duality into the supergravity fields via pure spinor formalism and show that a general class of fermionic transformations can be identified directly in the supergravity. In addition to discussing fermionic T-duality for the geometry AdS4 x CP3, dual to N=6 ABJM theory, we review work on other self-dual geometries. Finally, we present a short round-up of studies with a formal interest in fermionic T-duality.
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.
Path Integral Bosonization of Massive GNO Fermions
Park, Q H
1997-01-01
We show the quantum equivalence between certain symmetric space sine-Gordon models and the massive free fermions. In the massless limit, these fermions reduce to the free fermions introduced by Goddard, Nahm and Olive (GNO) in association with symmetric spaces $K/G$. A path integral formulation is given in terms of the Wess-Zumino-Witten action where the field variable $g$ takes value in the orthogonal, unitary, and symplectic representations of the group $G$ in the basis of the symmetric space. We show that, for example, such a path integral bosonization is possible when the symmetric spaces $K/G$ are $SU(N) the relation between massive GNO fermions and the nonabelian solitons, and explain the restriction imposed on the fermion mass matrix due to the integrability of the bosonic model.
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)
Cascading Multicriticality in Nonrelativistic Spontaneous Symmetry Breaking
Griffin, Tom; Horava, Petr; Yan, Ziqi
2015-01-01
Without Lorentz invariance, spontaneous global symmetry breaking can lead to multicritical Nambu-Goldstone modes with a higher-order low-energy dispersion $\\omega\\sim k^n$ ($n=2,3,\\ldots$), whose naturalness is protected by polynomial shift symmetries. Here we investigate the role of infrared divergences and the nonrelativistic generalization of the Coleman-Hohenberg-Mermin-Wagner (CHMW) theorem. We find novel cascading phenomena with large hierarchies between the scales at which the value of $n$ changes, leading to an evasion of the "no-go" consequences of the relativistic CHMW theorem.
The generalized fermion-bag approach
Chandrasekharan, Shailesh
2011-01-01
We present a new approach to some four-fermion lattice field theories which we call the generalized fermion bag approach. The basic idea is to identify unpaired fermionic degrees of freedom that cause sign problems and collect them in a bag. Paired fermions usually act like bosons and do not lead to sign problems. A resummation of all unpaired fermion degrees of freedom inside the bag is sufficient to solve the fermion sign problem in a variety of interesting cases. Using a concept of duality we then argue that the size of the fermion bags is small both at strong and weak couplings. This allows us to construct efficient algorithms in both these limits. Using the fermion bag approach, we study the quantum phase transition of the 3D massless lattice Thirrring model which is of interest in the context of Graphene. Using our method we are able to solve the model on lattices as large as $40^3$ with moderate computational resources. We obtain the precise location of the quantum critical point and the values of the ...
Mass of nonrelativistic meson from leading twist distribution amplitudes
Energy Technology Data Exchange (ETDEWEB)
Braguta, V. V., E-mail: braguta@mail.ru [Institute for High Energy Physics (Russian Federation)
2011-01-15
In this paper distribution amplitudes of pseudoscalar and vector nonrelativistic mesons are considered. Using equations of motion for the distribution amplitudes, relations are derived which allow one to calculate the masses of nonrelativistic pseudoscalar and vector meson if the leading twist distribution amplitudes are known. These relations can be also rewritten as relations between the masses of nonrelativistic mesons and infinite series of QCD operators, what can be considered as an exact version of Gremm-Kapustin relation in NRQCD.
Fermions in a Walecka-type cosmology
Ribas, Marlos O; Devecchi, Fernando P; Kremer, Gilberto M
2012-01-01
A simplified Walecka-type model is investigated in a cosmological scenario. The model includes fermionic, scalar and vector fields as sources. It is shown that their interactions, taking place in a Robertson-Walker metric, could be responsible for the transition of accelerated-decelerated periods in the early universe and a current accelerated regime. It is also discussed the role of the fermionic field as the promoter of the accelerated regimes in the early and the late stages of the universe.
Universality and ambiguity in fermionic effective actions
de Berredo-Peixoto, Guilherme; Shapiro, Ilya L
2012-01-01
We discuss an ambiguity in the one-loop effective action of massive fields which takes place in massive fermionic theories. The universality of logarithmic UV divergences in different space-time dimensions leads to the non-universality of the finite part of effective action, which can be called the non-local multiplicative anomaly. The general criteria of existence of this phenomena are formulated and applied to fermionic operators with different external fields.
Kittaka, Shunichiro; Aoki, Yuya; Shimura, Yasuyuki; Sakakibara, Toshiro; Seiro, Silvia; Geibel, Christoph; Steglich, Frank; Tsutsumi, Yasumasa; Ikeda, Hiroaki; Machida, Kazushige
2016-08-01
This paper presents the results of specific-heat and magnetization measurements, in particular their field-orientation dependence, on the first discovered heavy-fermion superconductor CeCu2Si2 (Tc˜0.6 K). We discuss the superconducting gap structure and the origin of the anomalous pair-breaking phenomena, leading, e.g., to the suppression of the upper critical field Hc 2, found in the high-field region. The data show that the anomalous pair breaking becomes prominent below about 0.15 K in any field direction, but occurs closer to Hc 2 for H ∥c . The presence of this anomaly is confirmed by the fact that the specific-heat and magnetization data satisfy standard thermodynamic relations. Concerning the gap structure, field-angle dependencies of the low-temperature specific heat within the a b and a c planes do not show any evidence for gap nodes. From microscopic calculations in the framework of a two-band full-gap model, the power-law-like temperature dependencies of C and 1 /T1 , reminiscent of nodal superconductivity, have been reproduced reasonably. These facts further support multiband full-gap superconductivity in CeCu2Si2 .
The doublet of Dirac fermions in the field of the non-Abelian monopole and parity selection rules
Redkov, V M
1998-01-01
The paper concerns a problem of Dirac fermion doublet in the external monopole potential arisen out of embedding the Abelian monopole solution in the non-Abe- lian scheme. In this particular case, the Hamiltonian is invariant under some symmetry operations consisting of an Abelian subgroup in the complex rotational group SO(3.C). This symmetry results in a certain (A)-freedom in choosing a discrete operator entering the complete set {H, j^{2}, j_{3}, N(A), K} . The same complex number A represents a parameter of the wave functions constructed. The generalized inversion-like operator N(A) implies its own (A-dependent) de- finition for scalar and pseudoscalar, and further affords some generalized N(A)-parity selection rules. It is shown that all different sets of basis func- tions Psi(A) determine the same Hilbert space. In particular, the functions Psi(A) decompose into linear combinations of Psi(A=0). However, the bases con- sidered turn out to be nonorthogonal ones when A is not real number; the latter corre...
A Signed Particle Formulation of Non-Relativistic Quantum Mechanics
Sellier, Jean Michel
2015-01-01
A formulation of non-relativistic quantum mechanics in terms of Newtonian particles is presented in the shape of a set of three postulates. In this new theory, quantum systems are described by ensembles of signed particles which behave as field-less classical objects which carry a negative or positive sign and interact with an external potential by means of creation and annihilation events only. This approach is shown to be a generalization of the signed particle Wigner Monte Carlo method which reconstructs the time-dependent Wigner quasi-distribution function of a system and, therefore, the corresponding Schroedinger time-dependent wave-function. Its classical limit is discussed and a physical interpretation, based on experimental evidences coming from quantum tomography, is suggested. Moreover, in order to show the advantages brought by this novel formulation, a straightforward extension to relativistic effects is discussed. To conclude, quantum tunnelling numerical experiments are performed to show the val...
Ion Injection at Non-relativistic Collisionless Shocks
Caprioli, Damiano; Spitkovsky, Anatoly
2014-01-01
We use kinetic hybrid simulations (kinetic ions - fluid electrons) to characterize the fraction of ions that are accelerated to non-thermal energies at non-relativistic collisionless shocks. We investigate the properties of the shock discontinuity and show that shocks propagating almost along the background magnetic field (quasi-parallel shocks) reform quasi-periodically on ion cyclotron scales. Ions that impinge on the shock when the discontinuity is the steepest are specularly reflected. This is a necessary condition for being injected, but it is not sufficient. Also by following the trajectories of reflected ions, we calculate the minimum energy needed for injection into diffusive shock acceleration, as a function of the shock inclination. We construct a minimal model that accounts for the ion reflection from quasi-periodic shock barrier, for the fraction of injected ions, and for the ion spectrum throughout the transition from thermal to non-thermal energies. This model captures the physics relevant for i...
Wilson Fermions with Four Fermion Interactions
Rantaharju, Jarno; Hietanen, Ari; Pica, Claudio; Sannino, Francesco
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 electroweak symmetry breaking these operators, at an effective level, are used to endow the Standard Model fermions with masses. Furthermore these operators, when sufficiently strong, can drastically modify the fundamental composite dynamics by, for example, turning a strongly coupled infrared conformal theory into a (near) conformal one with desirable features for model building. As first step, we study spontaneous chiral symmetry breaking for the lattice version of the NJL model.
Dynamical origin of low-mass fermions in Randall-Sundrum background
Fukazawa, K; Katsuki, Y; Muta, T; Ohkura, K; Fukazawa, Kenji; Inagaki, Tomohiro; Katsuki, Yasuhiko; Muta, Taizo; Ohkura, Kensaku
2003-01-01
We investigate a dynamical mechanism to generate fermion mass in the Randall-Sundrum background. We consider four-fermion interaction models where the fermion field propagates in an extra-dimension, i.e. the bulk four-fermion interaction model. It is assumed that two types of fermions with opposite parity exist in the bulk. We show that electroweak-scale mass is dynamically generated for a specific fermion anti-fermion condensation, even if all the scale parameters in the Lagrangian are set to the Planck scale.
Velocity in Lorentz-Violating Fermion Theories
Altschul, B D; Colladay, Don
2004-01-01
We consider the role of the velocity in Lorentz-violating fermionic quantum theory, especially emphasizing the nonrelativistic regime. Information about the velocity will be important for the kinematical analysis of scattering and other problems. Working within the minimal standard model extension, we derive new expressions for the velocity. We find that generic momentum and spin eigenstates may not have well-defined velocities. We also demonstrate how several different techniques may be used to shed light on different aspects of the problem. A relativistic operator analysis allows us to study the behavior of the Lorentz-violating Zitterbewegung. Alternatively, by studying the time evolution of Gaussian wave packets, we find that there are Lorentz-violating modifications to the wave packet spreading and the spin structure of the wave function.
Relativistic and Non-relativistic Equations of Motion
Mangiarotti, L
1998-01-01
It is shown that any second order dynamic equation on a configuration space $X$ of non-relativistic time-dependent mechanics can be seen as a geodesic equation with respect to some (non-linear) connection on the tangent bundle $TX\\to X$ of relativistic velocities. Using this fact, the relationship between relativistic and non-relativistic equations of motion is studied.
A generally-relativistic gauge classification of the Dirac fields
Fabbri, Luca
2016-01-01
We consider generally-relativistic gauge transformations for the spinorial fields finding two mutually exclusive but together exhaustive classes in which fermions are placed adding supplementary information to the results obtained by Lounesto, and identifying quantities analogous to the momentum vector and the Pauli-Lubanski axial vector we discuss how our results are similar to those obtained by Wigner; by taking into account the most general Dirac equations we will investigate the consequences for the dynamics: and in particular we shall address the problem of getting the non-relativistic approximation in a consistent way. We are going to comment on extensions.
Heavy dark matter annihilation from effective field theory.
Ovanesyan, Grigory; Slatyer, Tracy R; Stewart, Iain W
2015-05-29
We formulate an effective field theory description for SU(2)_{L} triplet fermionic dark matter by combining nonrelativistic dark matter with gauge bosons in the soft-collinear effective theory. For a given dark matter mass, the annihilation cross section to line photons is obtained with 5% precision by simultaneously including Sommerfeld enhancement and the resummation of electroweak Sudakov logarithms at next-to-leading logarithmic order. Using these results, we present more accurate and precise predictions for the gamma-ray line signal from annihilation, updating both existing constraints and the reach of future experiments.
Orbital magnetization of interacting Dirac fermions in graphene
Yan, Xin-Zhong; Ting, C. S.
2017-09-01
We present a formalism to calculate the orbital magnetization of interacting Dirac fermions under a magnetic field. In this approach, the divergence difficulty is overcome with a special limit of the derivative of the thermodynamic potential with respect to the magnetic field. The formalism satisfies the particle-hole symmetry of the Dirac fermions system. We apply the formalism to the interacting Dirac fermions in graphene. The charge and spin orderings and the exchange interactions between all the Landau levels are taken into account by the mean-field theory. The results for the orbital magnetization of interacting Dirac fermions are compared with that of noninteracting cases.
Nonrelativistic Quantum Mechanics with Fundamental Environment
Gevorkyan, Ashot S.
2011-03-01
Spontaneous transitions between bound states of an atomic system, "Lamb Shift" of energy levels and many other phenomena in real nonrelativistic quantum systems are connected within the influence of the quantum vacuum fluctuations ( fundamental environment (FE)) which are impossible to consider in the limits of standard quantum-mechanical approaches. The joint system "quantum system (QS) + FE" is described in the framework of the stochastic differential equation (SDE) of Langevin-Schrödinger (L-Sch) type, and is defined on the extended space R 3 ⊗ R { ξ}, where R 3 and R { ξ} are the Euclidean and functional spaces, respectively. The density matrix for single QS in FE is defined. The entropy of QS entangled with FE is defined and investigated in detail. It is proved that as a result of interaction of QS with environment there arise structures of various topologies which are a new quantum property of the system.
Staggered domain wall fermions
Hoelbling, Christian
2016-01-01
We construct domain wall fermions with a staggered kernel and investigate their spectral and chiral properties numerically in the Schwinger model. In some relevant cases we see an improvement of chirality by more than an order of magnitude as compared to usual domain wall fermions. Moreover, we present first results for four-dimensional quantum chromodynamics, where we also observe significant reductions of chiral symmetry violations for staggered domain wall fermions.
Fermions as topological objects
Yershov, V N
2002-01-01
A conceptual preon-based model of fermions is discussed. The preon is regarded as a topological object with three degrees of freedom in a dual three-dimensional manifold. It is shown that properties of this manifold give rise to a set of preon structures, which resemble three families of fermions. The number of preons in each structure is easily associated with the mass of a fermion. Being just a kind of zero-approximation to a theory of particles and interactions below the quark scale, our model however predicts masses of fermions with an accuracy of about 0.0002% without using any experimental input parameters.
Hyperfine splitting of the dressed hydrogen atom ground state in non-relativistic QED
Amour, L
2010-01-01
We consider a spin-1/2 electron and a spin-1/2 nucleus interacting with the quantized electromagnetic field in the standard model of non-relativistic QED. For a fixed total momentum sufficiently small, we study the multiplicity of the ground state of the reduced Hamiltonian. We prove that the coupling between the spins of the charged particles and the electromagnetic field splits the degeneracy of the ground state.
Quantization of Interacting Non-Relativistic Open Strings using Extended Objects
Arias, P J; Fuenmayor, E; Leal, L; Leal, Lorenzo
2005-01-01
Non-relativistic charged open strings coupled with Abelian gauge fields are quantized in a geometric representation that generalizes the Loop Representation. The model comprises open-strings interacting through a Kalb-Ramond field in four dimensions. It is shown that a consistent geometric-representation can be built using a scheme of ``surfaces and lines of Faraday'', provided that the coupling constant (the ``charge'' of the string) is quantized.
Nonrelativistic QED expansion for the electron self-energy
Patkóš, V.; Šimsa, D.; Zamastil, J.
2017-01-01
The recently proposed relativistic multipole expansion (RME) of the self-energy effect suggests some observations on the nonrelativistic expansion of the effect. First, the nature of the series for the one-loop self-energy of an electron bound by the Coulomb field of the nucleus is clarified. It is shown that the expansion of the energy shift caused by the self-energy effect contains terms of the form α (Zα ) 7ln(Z α ) , α (Zα ) 8ln3(Z α ) , α (Zα ) 9ln2(Z α ) , α (Zα ) 10ln4(Z α ) , and so on. Here Z is the charge of the nucleus. The origin of these terms is traced back to the logarithmic divergence of the Dirac S -wave function at the origin. These terms eventually lead to breakdown of the nonrelativistic quantum electrodynamics approach. Second, at leading order relativistic multipole expansion requires an evaluation of the "extended Bethe logarithm" (EBL). When expanded in series in Z α EBL reduces at leading order to the ordinary Bethe logarithm. However, it is argued that it is both more accurate and easier to calculate the EBL than the ordinary Bethe logarithm. Both variants of the Bethe logarithm can be calculated by means of the pseudostate method. An improvement of this method is suggested. Finally, the contribution of the combined self-energy vacuum polarization contribution to the Lamb shift in muonic hydrogen for the 1 s -4 s and 2 p -4 p states by means of the EBL is calculated. For cases that had already been calculated the results reported here are more accurate than the previous ones.
Evolution of boson-fermion stars
Valdez-Alvarado, Susana; Palenzuela, Carlos; Alic, Daniela; Ureña-López, L. Arturo; Becerril, Ricardo
2012-08-01
The boson-fermion stars can be modeled with a complex scalar field coupled minimally to a perfect fluid (i.e., without viscosity and non-dissipative). We present a study of these solutions and their dynamical evolution by solving numerically the Einstein-Klein-Gordon-Hydrodynamic (EKGHD) system. It is shown that stable configurations exist, but stability of general configurations depends finely upon the number of bosons and fermions.
A special fermionic generalization of lineal gravity
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The central extension of the (1+1)-dimensional Poincaré algebra by including fermionic charges which obey not supersymmetric algebra, but a special graded algebra containing in the right hand side a central element only is obtained. The corresponding theory being the fermionic extension of the lineal gravity is proposed. We considered the algebra of generators, the field transformations and found Lagrangian and equation of motion, then we derived the Casimir operator and obtained the constant black hole mass.
Energy Technology Data Exchange (ETDEWEB)
Yang, Mou, E-mail: yangmou1222@gmail.com [Laboratory of Quantum Information Technology, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Cui, Yan; Wang, Rui-Qiang; Zhao, Hong-Bo [Laboratory of Quantum Information Technology, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China)
2012-03-05
We investigate the electronic structure of graphene ribbons under the competition between lateral electric and normal magnetic fields. The squeezing of quantum level spacings caused by either field is studied. Based on the knowledge of the dispersion under both fields, we analyze the electronic trajectories near the junctions of different electric and magnetic fields configurations. The junctions can split and join electron beams, and the conductance is quite robust against disorder near the junction interfaces. These junction devices can be used as bricks for building more complicated interference devices. -- Highlights: ► Unified physical picture of graphene ribbon under electric and magnetic fields is provided. ► Squeezing of level spacings caused by electric and magnetic fields is investigated. ► Graphene devices for electron beam split and joint are proposed.
Spinons and parafermions in fermion cosets
Cabra, D C
1997-01-01
We introduce a set of gauge invariant fermion fields in fermionic coset models and show that they play a very central role in the description of several Conformal Field Theories (CFT's). In particular we discuss the explicit realization of primaries and their OPE in unitary minimal models, parafermion fields in $Z_k$ CFT's and that of spinon fields in $SU(N)_k, k=1$ Wess-Zumino-Witten models (WZW) theories. The higher level case ($k>1$) will be briefly discussed. Possible applications to QHE systems and spin-ladder systems are addressed.
Chiral fermions in asymptotically safe quantum gravity
Energy Technology Data Exchange (ETDEWEB)
Meibohm, J. [Gothenburg University, Department of Physics, Goeteborg (Sweden); Universitaet Heidelberg, Institut fuer Theoretische Physik, Heidelberg (Germany); Pawlowski, J.M. [Universitaet Heidelberg, Institut fuer Theoretische Physik, Heidelberg (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung mbH, ExtreMe Matter Institute EMMI, Darmstadt (Germany)
2016-05-15
We study the consistency of dynamical fermionic matter with the asymptotic safety scenario of quantum gravity using the functional renormalisation group. Since this scenario suggests strongly coupled quantum gravity in the UV, one expects gravity-induced fermion self-interactions at energies of the Planck scale. These could lead to chiral symmetry breaking at very high energies and thus to large fermion masses in the IR. The present analysis which is based on the previous works (Christiansen et al., Phys Rev D 92:121501, 2015; Meibohm et al., Phys Rev D 93:084035, 2016), concludes that gravity-induced chiral symmetry breaking at the Planck scale is avoided for a general class of NJL-type models. We find strong evidence that this feature is independent of the number of fermion fields. This finding suggests that the phase diagram for these models is topologically stable under the influence of gravitational interactions. (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...
Cirilo-Lombardo, Diego Julio
2015-01-01
The 2-dimensional charge transport with parallel (in plane) magnetic field is considered from the physical and mathematical point of view. To this end, we start with the magnetic field parallel to the plane of charge transport, in sharp contrast to the configuration described by the theorems of Aharonov and Casher where the magnetic field is perpendicular. We explicitly show that the specific form of the arising equation enforce the respective field solution to fulfil the Majorana condition. Consequently, as soon any physical system is represented by this equation, the rise of fields with Majorana type behaviour is immediately explained and predicted. In addition, there exists a quantized particular phase that removes the action of the vector potential producing interesting effects. Such new effects are able to explain due the geometrical framework introduced, several phenomenological results recently obtained in the area of spintronics and quantum electronic devices. The quantum ring as spin filter is worked...
Fermion helicity flip in higher-derivative electromagnetism
Energy Technology Data Exchange (ETDEWEB)
Accioly, A.J. [Instituto de Fisica Teorica (IFT), Sao Paulo, SP (Brazil); Mukai, H. [Universidade Estadual de Maringa, PR (Brazil). Dept. de Fisica
1996-10-01
It is shown that massive fermions have their helicity flipped on account of their interaction with an electromagnetic field described by Podolsky`s generalized electrodynamics. Massless fermions, in turn, seem to be unaffected by the electromagnetic field as far as their helicity is concerned. (author).
Covariant geometric quantization of non-relativistic Hamiltonian mechanics
Giachetta, G; Sardanashvily, G
2000-01-01
We provide geometric quantization of the vertical cotangent bundle V^*Q equipped with the canonical Poisson structure. This is a momentum phase space of non-relativistic mechanics with the configuration bundle Q -> R. The goal is the Schrodinger representation of V^*Q. We show that this quantization is equivalent to the fibrewise quantization of symplectic fibres of V^*Q -> R, that makes the quantum algebra of non-relativistic mechanics an instantwise algebra. Quantization of the classical evolution equation defines a connection on this instantwise algebra, which provides quantum evolution in non-relativistic mechanics as a parallel transport along time.
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.
Casimir operator dependences of nonperturbative fermionic QCD amplitudes
Fried, H. M.; Grandou, T.; Hofmann, R.
2016-07-01
In eikonal and quenched approximations, it is argued that the strong coupling fermionic QCD Green’s functions and related amplitudes depart from a sole dependence on the SUc(3) quadratic Casimir operator, C2f, evaluated over the fundamental gauge group representation. Noted in nonrelativistic quark models and in a nonperturbative generalization of the Schwinger mechanism, an additional dependence on the cubic Casimir operator shows up, in contradistinction with perturbation theory and other nonperturbative approaches. However, it accounts for the full algebraic content of the rank-2 Lie algebra of SUc(3). Though numerically subleading effects, cubic Casimir dependences, here and elsewhere, appear to be a signature of the nonperturbative fermionic sector of QCD.
Scarring of Dirac fermions in chaotic billiards.
Ni, Xuan; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso
2012-07-01
Scarring in quantum systems with classical chaotic dynamics is one of the most remarkable phenomena in modern physics. Previous works were concerned mostly with nonrelativistic quantum systems described by the Schrödinger equation. The question remains outstanding of whether truly relativistic quantum particles that obey the Dirac equation can scar. A significant challenge is the lack of a general method for solving the Dirac equation in closed domains of arbitrary shape. In this paper, we develop a numerical framework for obtaining complete eigensolutions of massless fermions in general two-dimensional confining geometries. The key ingredients of our method are the proper handling of the boundary conditions and an efficient discretization scheme that casts the original equation in a matrix representation. The method is validated by (1) comparing the numerical solutions to analytic results for a geometrically simple confinement and (2) verifying that the calculated energy level-spacing statistics of integrable and chaotic geometries agree with the known results. Solutions of the Dirac equation in a number of representative chaotic geometries establish firmly the existence of scarring of Dirac fermions.
Energy Technology Data Exchange (ETDEWEB)
Hussain, S.; Mahmood, S.; Rehman, Aman-ur- [Theoretical Physics Division (TPD), PINSTECH, P.O. Nilore, Islamabad 44000, Pakistan and Pakistan Institute of Engineering and Applied Sciences (PIEAS), P.O. Nilore, Islamabad 44000 (Pakistan)
2014-11-15
Linear and nonlinear propagation of magnetosonic waves in the perpendicular direction to the ambient magnetic field is studied in dense plasmas for non-relativistic and ultra-relativistic degenerate electrons pressure. The sources of nonlinearities are the divergence of the ions and electrons fluxes, Lorentz forces on ions and electrons fluids and the plasma current density in the system. The Korteweg-de Vries equation for magnetosonic waves propagating in the perpendicular direction of the magnetic field is derived by employing reductive perturbation method for non-relativistic as well as ultra-relativistic degenerate electrons pressure cases in dense plasmas. The plots of the magnetosonic wave solitons are also shown using numerical values of the plasma parameters such a plasma density and magnetic field intensity of the white dwarfs from literature. The dependence of plasma density and magnetic field intensity on the magnetosonic wave propagation is also pointed out in dense plasmas for both non-relativistic and ultra-relativistic degenerate electrons pressure cases.
Semiclassical fermion pair creation in de Sitter spacetime
Energy Technology Data Exchange (ETDEWEB)
Stahl, Clément, E-mail: clement.stahl@icranet.org; Eckhard, Strobel, E-mail: eckhard.strobel@irap-phd.eu [ICRANet, Piazzale della Repubblica 10, 65122 Pescara (Italy); Dipartimento di Fisica, Università di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome (Italy); Université de Nice Sophia Antipolis, 28 Avenue de Valrose, 06103 Nice Cedex 2 (France)
2015-12-17
We present a method to semiclassically compute the pair creation rate of bosons and fermions in de Sitter spacetime. The results in the bosonic case agree with the ones in the literature. We find that for the constant electric field the fermionic and bosonic pair creation rate are the same. This analogy of bosons and fermions in the semiclassical limit is known from several flat spacetime examples.
Fermions with a domain-wall mass: explicit greens function and anomaly cancellation
Chandrasekharan, Shailesh
1994-04-01
We calculate the explicit Greens function for fermions in 2+1 dimensions, with a domain wall mass. We then show a calculation demonstrating the anomaly cancellation when such fermions move in the background of an abelian gauge field.
Cirilo-Lombardo, Diego Julio
2015-06-01
The two-dimensional charge transport with parallel (in plane) magnetic field is considered from the physical and mathematical point of view. To this end, we start with the magnetic field parallel to the plane of charge transport, in sharp contrast to the configuration described by the theorems of Aharonov and Casher where the magnetic field is perpendicular. We explicitly show that the specific form of the arising equation enforces the respective field solution to fulfill the Majorana condition. Consequently, as soon any physical system is represented by this equation, the rise of fields with Majorana type behavior is immediately explained and predicted. In addition, there exists a quantized particular phase that removes the action of the vector potential producing interesting effects. Such new effects are able to explain due to the geometrical framework introduced, several phenomenological results recently obtained in the area of spintronics and quantum electronic devices. The quantum ring as spin filter is worked out in this framework and also the case of the quantum Hall effect.
Vortex solutions in axial or chiral coupled non-relativistic spinor- Chern-Simons theory
Németh, Z A
1997-01-01
The interaction of a spin 1/2 particle (described by the non-relativistic "Dirac" equation of Lévy-Leblond) with Chern-Simons gauge fields is studied. It is shown, that similarly to the four dimensional spinor models, there is a consistent possibility of coupling them also by axial or chiral type currents. Static self dual vortex solutions together with a vortex-lattice are found with the new couplings.
Li, Xiao; Roy, Bitan; Das Sarma, S.
2016-11-01
We theoretically address the effects of strong magnetic fields in three-dimensional Weyl semimetals (WSMs) built out of Weyl nodes with a monopole charge n . For n =1 , 2, and 3 we realize single, double, and triple WSM, respectively, and the monopole charge n determines the integer topological invariant of the WSM. Within the linearized continuum description, the quasiparticle spectrum is then composed of Landau levels (LLs), containing exactly n number of chiral zeroth Landau levels (ZLLs), irrespective of the orientation of the magnetic field. In the presence of strong backscattering, for example (due to quenched disorder associated with random impurities), these systems generically give rise to longitudinal magnetotransport. Restricting ourselves to the quantum limit (and assuming only the subspace of the ZLLs to be partially filled) and mainly accounting for Gaussian impurities, we show that the longitudinal magnetoconductivity (LMC) in all members of the Weyl family displays a positive linear-B scaling when the field is applied along the axis that separates the Weyl nodes. But, in double and triple WSM, LMC displays a smooth crossover to a nonlinear B dependence as the field is tilted away from such a high-symmetry direction. In addition, due to the enhanced density of states, the LL quantization can trigger instabilities toward the formation of translational symmetry-breaking density-wave orderings for sufficiently weak interaction (BCS instability), which gaps out the ZLLs. Concomitantly as the temperature (magnetic field) is gradually decreased (increased) the LMC becomes negative. Thus WSMs with arbitrary monopole charge (n ) can host an intriguing interplay of LL quantization, longitudinal magnetotransport (a possible manifestation of one-dimensional chiral or axial anomaly), and density-wave ordering, when placed in a strong magnetic field.
Towards Partial Compositeness on the Lattice: Baryons with Fermions in Multiple Representations
DeGrand, Thomas A; Jay, William I; Neil, Ethan T; Shamir, Yigal; Svetitsky, Benjamin
2016-01-01
We describe our recent lattice study of SU(4) gauge theory with fermions in the fundamental and sextet representations. In this theory, a new type of baryon consists of quarks in both representations. The spectrum of these "chimera baryons" has a straightforward interpretation in terms of a non-relativistic quark model based on SU(4). Our results are particularly relevant to composite Higgs models in which the top quark is partially composite.
A Table of Third and Fourth Order Feynman Diagrams of the Interacting Fermion Green's Function
Mathar, R J
2005-01-01
The Feynman diagrams of the Green's function expansion of fermions interacting with a non-relativistic 2-body interaction are displayed in first, second and third order of the interaction as 2, 10 and 74 diagrams, respectively. A name convention for the diagrams is proposed and then used to tabulate the 706 diagrams of fourth order. The Hartree-Fock approximation summons up 2, 8, 40 and 224 of them, respectively.
Symmetry and Covariance of Non-relativistic Quantum Mechanics
Omote, Minoru; kamefuchi, Susumu
2000-01-01
On the basis of a 5-dimensional form of space-time transformations non-relativistic quantum mechanics is reformulated in a manifestly covariant manner. The resulting covariance resembles that of the conventional relativistic quantum mechanics.
Nonrelativistic limit of solution of radial quasipotential equations
Energy Technology Data Exchange (ETDEWEB)
Minh, Vu.X.; Kadyshevskii, V.G.; Zhidkov, E.P.
1986-10-01
For the S-wave case, solutions of relativistic radial quasipotential equations that degenerate in the limit c ..-->.. infinity into the Jost solutions of the corresponding nonrelativistic radial Schrodinger equations are found.
Fermion dispersion in axion medium
Mikheev, N. V.; Narynskaya, E. N.
2008-01-01
The interaction of a fermion with the dense axion medium is investigated for the purpose of finding an axion medium effect on the fermion dispersion. It is shown that axion medium influence on the fermion dispersion under astrophysical conditions is negligible small if the correct Lagrangian of the axion-fermion interaction is used.
Xin, W; Xin, Wang; Jiarong, Li
2000-01-01
Within the real-time formalism (RTF) of thermal field theory,we apply the hard thermal loop (HTL) resummation technique to calculating effective two-loop thermodynamic potential in quark-gluon plasma (QGP) and its renormalization. The result with collective effects is obtained, which is valid for an arbitrary number of quark flavors with masses.
Corrections to the Nonrelativistic Ground Energy of a Helium Atom
Institute of Scientific and Technical Information of China (English)
段一士; 刘玉孝; 张丽杰
2004-01-01
Considering the nuclear motion, we present the nonrelativistic ground energy of a helium atom by using a simple effective variational wavefunction with a flexible parameter k. Based on the result, the relativistic and radiative corrections to the nonrelativistic Hamiltonian are discussed. The high precision value of the helium ground energy is evaluated to be -2.90338 a.u. With the relative error 0.00034%.
Lattice theory of nonequilibrium fermion production
Energy Technology Data Exchange (ETDEWEB)
Gelfand, Daniil
2014-07-22
In this thesis we investigate non-equilibrium production of fermionic particles using modern lattice techniques. The presented applications range from preheating after inflation in the early Universe cosmology to pre-thermalization dynamics in heavy-ion collisions as well as pair production and string breaking in a lower-dimensional model of quantum chromodynamics. Strong enhancement of fermion production in the presence of overoccupied bosons is observed in scalar models undergoing instabilities. Both parametric resonance and tachyonic instability are considered as scenarios for preheating after inflation. The qualitative and quantitative features of the resulting fermion distribution are found to depend largely on an effective coupling parameter. In order to simulate fermions in three spatial dimensions we apply a stochastic low-cost lattice algorithm, which we verify by comparison with an exact lattice approach and with a functional method based on a coupling expansion. In the massive Schwinger model, we analyse the creation of fermion/anti-fermion pairs from homogeneous and inhomogeneous electric fields and observe string formation between charges. As a follow-up we study the dynamics of string breaking and establish a two-stage process, consisting of the initial particle production followed by subsequent charge separation and screening. In quantum chromodynamics, our focus lies on the properties of the quark sector during turbulent bosonic energy cascade as well as on the isotropization of quarks and gluons starting from different initial conditions.
Fermions as Topological Objects
Directory of Open Access Journals (Sweden)
Yershov V. N.
2006-01-01
Full Text Available A preon-based composite model of the fundamental fermions is discussed, in which the fermions are bound states of smaller entities — primitive charges (preons. The preon is regarded as a dislocation in a dual 3-dimensional manifold — a topological object with no properties, save its unit mass and unit charge. It is shown that the dualism of this manifold gives rise to a hierarchy of complex structures resembling by their properties three families of the fundamental fermions. Although just a scheme for building a model of elementary particles, this description yields a quantitative explanation of many observable particle properties, including their masses.
de Brito, K P S
2016-01-01
Spinor fields on 5-dimensional Lorentzian manifolds are classified, according to the geometric Fierz identities that involve their bilinear covariants. Based upon this classification that generalises the celebrated 4-dimensional Lounesto classification of spinor fields, new non-trivial classes of 5-dimensional spinor fields are, hence, found, with important potential applications regarding bulk fermions and their subsequent localisation on brane-worlds. In addition, quaternionic bilinear covariants are used to derive the quaternionic spin density, through the truncated exterior bundle. In order to accomplish a realisation of these new spinors, a Killing vector field is constructed on the horizon of 5-dimensional Kerr black holes. This Killing vector field is shown to reach the time-like Killing vector field at the spatial infinity, through a current 1-form density, constructed with the derived new spinor fields. The current density is, moreover, expressed as the f\\"unfbein components, assuming a condensed for...
de Brito, K. P. S.; da Rocha, Roldão
2016-10-01
The spinor fields on 5-dimensional Lorentzian manifolds are classified according to the geometric Fierz identities, which involve their bilinear covariants. Based upon this classification, which generalises the celebrated 4-dimensional Lounesto classification of spinor fields, new non-trivial classes of 5-dimensional spinor fields are hence found, with important potential applications regarding bulk fermions and their subsequent localisation on brane-worlds. In addition, quaternionic bilinear covariants are used to derive the quaternionic spin density through the truncated exterior bundle. In order to accomplish the realisation of these new spinors, a Killing vector field is constructed on the horizon of a 5-dimensional Kerr black hole. This Killing vector field is shown to reach the time-like Killing vector field at spatial infinity through a current 1-form density, constructed with the new derived spinor fields. The current density is, moreover, expressed as the fünfbein component, assuming a condensed form.
Fermions as sources of accelerated regimes in cosmology
Ribas, M O; Kremer, G M
2005-01-01
In this work it is investigated if fermionic sources could be responsible for accelerated periods during the evolution of a universe where a matter field would answer for the decelerated period. The self-interaction potential of the fermionic field is considered as a function of the scalar and pseudo-scalar invariants. Irreversible processes of energy transfer between the matter and gravitational fields are also considered. It is shown that the fermionic field could behave like an inflaton field in the early universe and as dark energy for an old universe.
On the trace anomaly of a Weyl fermion
Bastianelli, Fiorenzo
2016-01-01
We calculate the trace anomaly of a Weyl fermion coupled to gravity by using Fujikawa's method supplemented by a consistent regulator. The latter is constructed out of Pauli-Villars regulating fields. The motivation for presenting such a calculation stems from recent studies that suggest that the trace anomaly of chiral fermions in four dimensions might contain an imaginary part proportional to the Pontryagin density. We find that the trace anomaly of a Weyl fermion is given by half the trace anomaly of a Dirac fermion, so that no imaginary part proportional to the Pontryagin density is seen to arise.
Constraints on dark matter annihilation to fermions and a photon
Chowdhury, Debtosh; Laha, Ranjan
2016-01-01
We consider Majorana dark matter annihilation to fermion - anti-fermion pair and a photon in the effective field theory paradigm, by introducing dimension 6 and dimension 8 operators in the Lagrangian. For a given value of the cut-off scale, the latter dominates the annihilation process for heavier dark matter masses. We find a cancellation in the dark matter annihilation to a fermion - anti-fermion pair when considering the interference of the dimension 6 and the dimension 8 operators. Constraints on the effective scale cut-off is derived while considering indirect detection experiments and the relic density requirements and then comparing them to the bound coming from collider experiments.
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.
A novel and economical explanation for SM fermion masses and mixings
Hernández, A. E. Cárcamo
2016-09-01
I propose the first multiscalar singlet extension of the standard model (SM), which generates tree level top quark and exotic fermion masses as well as one and three loop level masses for charged fermions lighter than the top quark and for light active neutrinos, respectively, without invoking electrically charged scalar fields. That model, which is based on the S3× Z8 discrete symmetry, successfully explains the observed SM fermion mass and mixing pattern. The charged exotic fermions induce one loop level masses for charged fermions lighter than the top quark. The Z8 charged scalar singlet χ generates the observed charged fermion mass and quark mixing pattern.
Effective field theories for heavy Majorana neutrinos in a thermal bath
Energy Technology Data Exchange (ETDEWEB)
Biondini, Simone
2016-05-06
In the leptogenesis framework Majorana neutrinos are at the origin of the baryon asymmetry in the universe. We develop an effective field theory for non-relativistic Majorana fermions and we apply it to the case of a heavy Majorana neutrino decaying in a hot plasma of Standard Model particles, whose temperature is much smaller than the mass of the Majorana neutrino but still much larger than the electroweak scale. Moreover we compute systematically thermal corrections to the CP asymmetries in the Majorana neutrino decays.
Mass Spectrum of Fermion on Bloch Branes with New Scalar-fermion Coupling
Xie, Qun-Ying; Zhao, Zhen-Hua; Du, Yun-Zhi; Zhang, Yu-Peng
2015-01-01
In order to localize a left- or right-handed fermion zero mode on a thick brane, one usually introduces the Yukawa coupling $\\eta \\bar{\\Psi} F(\\chi) \\Psi$ between a bulk fermion and the background scalar field $\\chi$. However, the Yukawa coupling will do not work if the background scalar is an even function of the extra dimension. Recently, Ref. [Phy. Rev. \\textbf{D} 89 (2014) 086001] has presented a new scalar-fermion coupling form $\\lambda \\bar \\Psi \\Gamma^M \\partial_M F(\\chi) \\gamma^5 \\Psi$ in order to deal with this problem. In this paper, we investigate the localization and mass spectrum of fermion on the Bloch brane by using the new scalar-fermion coupling with $F(\\chi)=\\chi^n$. It is found that the effective potentials have rich structure and may be volcano-like, finite square well-like, and infinite potentials, which depend on the parameter $n$. As a result, there may appear some resonant KK fermions, finite or infinite numbers of bound KK fermions.
Anomalous Hall Effect for chiral fermions
Zhang, P -M
2014-01-01
Semiclassical chiral fermions manifest the anomalous spin-Hall effect: when put into a pure electric field, they suffer a side jump, analogous to what happens to their massive counterparts in non-commutative mechanics. The transverse shift is consistent with the conservation of the angular momentum. In a pure magnetic field a cork-screw-like, spiraling motion is found.
Semiclassical Theory of Fermions
Florentino Ribeiro, Raphael
2016-01-01
A blend of non-perturbative semiclassical techniques is employed to systematically construct approximations to noninteracting many-fermion systems (coupled to some external potential mimicking the Kohn-Sham potential of density functional theory). In particular, uniform asymptotic approximations are obtained for the particle and kinetic energy density in terms of the external potential acting on the fermions and the Fermi energy. Dominant corrections to the classical limit of quantum mechanic...
Fermionic coset realization of the critical Ising model
Cabra, D C; Rothe, K D
1995-01-01
We obtain an explicit realization of all the primary fields of the Ising model in terms of a conformal field theory of constrained fermions. The four-point correlators of the energy, order and disorder operators are explicitly calculated.
Nonrelativistic quantum mechanics with consideration of influence of fundamental environment
Energy Technology Data Exchange (ETDEWEB)
Gevorkyan, A. S., E-mail: g_ashot@sci.am [NAS of Armenia, Institute for Informatics and Automation Problems (Armenia)
2013-08-15
Spontaneous transitions between bound states of an atomic system, the 'Lamb Shift' of energy levels and many other phenomena in real nonrelativistic quantum systems are connected with the influence of the quantum vacuum fluctuations (fundamental environment (FE)), which are impossible to consider in the framework of standard quantum-mechanical approaches. The joint system quantum system (QS) and FE is described in the framework of the stochastic differential equation (SDE) of Langevin-Schroedinger type and is defined on the extended space Double-Struck-Capital-R {sup 3} Circled-Times {Xi}{sup n}, where Double-Struck-Capital-R {sup 3} and {Xi}{sup n} are the Euclidean and functional spaces, respectively. The method of stochastic density matrix is developed and the von Neumann equation for reduced density matrix of QS with FE is generalized. The entropy of QS entangled with FE is defined and investigated. It is proved that the interaction of QS with the environment leads to emerging structures of various topologies which present new quantum-field properties of QS. It is shown that when the physical system (irrelatively to its being micro ormacro) breaks up into two fragments by means of FE, there arises between these fragments a nonpotential interaction which does not disappear at large distances.
Nonrelativistic quantum mechanics with consideration of influence of fundamental environment
Gevorkyan, A. S.
2013-08-01
Spontaneous transitions between bound states of an atomic system, the "Lamb Shift" of energy levels and many other phenomena in real nonrelativistic quantum systems are connected with the influence of the quantum vacuum fluctuations ( fundamental environment (FE)), which are impossible to consider in the framework of standard quantum-mechanical approaches. The joint system quantum system (QS) and FE is described in the framework of the stochastic differential equation (SDE) of Langevin-Schrödinger type and is defined on the extended space ℝ3⊗Ξ n , where ℝ3 and Ξ n are the Euclidean and functional spaces, respectively. The method of stochastic density matrix is developed and the von Neumann equation for reduced density matrix of QS with FE is generalized. The entropy of QS entangled with FE is defined and investigated. It is proved that the interaction of QS with the environment leads to emerging structures of various topologies which present new quantum-field properties of QS. It is shown that when the physical system (irrelatively to its being micro ormacro) breaks up into two fragments by means of FE, there arises between these fragments a nonpotential interaction which does not disappear at large distances.
Quark Seesaw Vectorlike Fermions and Diphoton Excess
Dev, P S Bhupal; Zhang, Yongchao
2015-01-01
We present a possible interpretation of the recent diphoton excess reported by the $\\sqrt s=13$ TeV LHC data in quark seesaw left-right models with vectorlike fermions proposed to solve the strong $CP$ problem without the axion. The gauge singlet real scalar field responsible for the mass of the vectorlike fermions has the right production cross section and diphoton branching ratio to be identifiable with the reported excess at around 750 GeV diphoton invariant mass. Various ways to test this hypothesis as more data accumulates at the LHC are proposed. In particular, we find that for our interpretation to work, there is an upper limit on the right-handed scale $v_R$, which depends on the Yukawa coupling of singlet Higgs field to the vectorlike fermions.
Ambiguities and Subtleties in Fermion Mass Terms
Cheng, Yifan
2013-01-01
This is a review on structure of the fermion mass terms of the Standard Model extended with the so-called "right-handed neutrinos" or "sterile neutrinos". The review is meant to be pedagogical, with detailed mathematics presented beyond the level one can find any easily in the literature. The discussions, however, bring up important subtleties and ambiguities about the subject that may be less than well appreciated. In fact, the naive perspective of the nature and masses of fermions as one would easily drawn from the presentations of fermion fields and their equations of motion from a typical textbook on quantum field theory leads to some confusing or even wrong statements which we clarify here. In particular, we illustrate clearly that a Dirac fermion mass eigenstate is mathematically equivalent to two degenerated Majorana fermion mass eigenstates at least so long as the mass terms are concerned. There are further ambiguities and subtleties in the exact description of the eigenstate(s). For the case of the n...
New Chiral Fermions, a New Gauge Interaction, Dirac Neutrinos, and Dark Matter
de Gouvea, André
2015-01-01
We propose that all light fermionic degrees of freedom, including the Standard Model (SM) fermions and all possible light beyond-the-standard-model fields, are chiral with respect to some spontaneously broken abelian gauge symmetry. Hypercharge, for example, plays this role for the SM fermions. We introduce a new symmetry, $U(1)_{\
Quantization of fermions on Kerr space-time
Casals, Marc; Dolan, Sam R.; Nolan, Brien C.; Ottewill, Adrian C.; Winstanley, Elizabeth
2013-03-01
We study a quantum fermion field on a background nonextremal Kerr black hole. We discuss the definition of the standard black hole quantum states (Boulware, Unruh, and Hartle-Hawking), focussing particularly on the differences between fermionic and bosonic quantum field theory. Since all fermion modes (both particle and antiparticle) have positive norm, there is much greater flexibility in how quantum states are defined compared with the bosonic case. In particular, we are able to define a candidate Boulware-like state, empty at both past and future null infinity, and a candidate Hartle-Hawking-like equilibrium state, representing a thermal bath of fermions surrounding the black hole. Neither of these states have analogues for bosons on a nonextremal Kerr black hole and both have physically attractive regularity properties. We also define a number of other quantum states, numerically compute differences in expectation values of the fermion current and stress-energy tensor between two states, and discuss their physical properties.
Interacting composite fermions
DEFF Research Database (Denmark)
nrc762, nrc762
2016-01-01
dominates. The interaction between composite fermions in the second Λ level (composite fermion analog of the electronic Landau level) satisfies this property, and recent studies have supported unconventional fractional quantum Hall effect of composite fermions at ν∗=4/3 and 5/3, which manifests...... as fractional quantum Hall effect of electrons at ν=4/11, 4/13, 5/13, and 5/17. I investigate in this article the nature of the fractional quantum Hall states at ν=4/5, 5/7, 6/17, and 6/7, which correspond to composite fermions at ν∗=4/3, 5/3, and 6/5, and find that all these fractional quantum Hall states...... are conventional. The underlying reason is that the interaction between composite fermions depends substantially on both the number and the direction of the vortices attached to the electrons. I also study in detail the states with different spin polarizations at 6/17 and 6/7 and predict the critical Zeeman...
Are non-relativistic neutrinos the dark matter particles?
Nieuwenhuizen, Theo M.
2010-06-01
The dark matter of a spherical, relaxed galaxy cluster is modeled by isothermal, non-interacting fermions; the galaxies and X-ray gas by isothermal classical distributions. A fit to lensing data of the cluster Abell 1689 works well and yields a mass of a few eV. This low value casts doubt on the existence of a Cold Dark Matter particle. The best case is the neutrino, for which in the cluster all 12 left- and righthanded modes are available. The fit gives an average mass 1.45(h/0.70)1/2 eV, with 2% error, while neutrino oscillations bring deviations of order meV. A neutrino mass between 0.2 and 2 eV will be searched in the Katrin experiment in 2012. The ideal value is mν = Yeme = 1.4998 eV, where Ye = 23/4GF1/2me is the Yukawa coupling of the electron. It occurs for reduced Hubble constant h = 0.744 with 4% error, right on top of and slightly sharper than the presently best supernova value of Riess et al. 2009, h = 0.742 with 4.8% error. In the cluster the neutrinos have a temperature of 0.045 K and a de Broglie length of 0.20 mm. They establish a quantum structure of several million light years across, the largest known in the Universe. The virial α-particle temperature of 9.9+/-1.1 keV/kB coincides with the average one of X-rays, while also the gas profile comes out well. Active neutrinos alone with the 1.45 eV mass give some 9.5% dark matter, more than allowed by the cold dark matter papradigm. A dark matter fraction of some 19%, Ων = (h/0.70)-3/20.189 (4), occurs for 12 degrees of freedom, i. e., for 3 families of left plus right handed neutrinos. The sterile modes may be produced in the early universe if there is a small Majorana mass matrix of order meV, on top of the Dirac matrix with ~1.45 eV masses. The neutrinos are free-streaming in the early universe and play no role during the decoupling. But now they are not homogeneous anymore. They condense on the Abell 1689 cluster fairly late, at redshift z~6-8, a prediction testable in future observations
Non-Relativistic Limit of the Dirac Equation
Ajaib, Muhammad Adeel
2016-01-01
We show that the first order form of the Schrodinger equation proposed in [1] can be obtained from the Dirac equation in the non-relativistic limit. We also show that the Pauli Hamiltonian is obtained from this equation by requiring local gauge invariance. In addition, we study the problem of a spin up particle incident on a finite potential barrier and show that the known quantum mechanical results are obtained. Finally, we consider the symmetric potential well and show that the quantum mechanical expression for the quantized energy levels of a particle is obtained with periodic boundary conditions. Based on these conclusions, we propose that the equation introduced in [1] is the non-relativistic limit of the Dirac equation and more appropriately describes spin 1/2 particles in the non-relativistic limit.
Fermions tunneling from the Horowitz-Strominger Dilaton black hole
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Based on the work of Kerner and Mann, fermions tunneling from the Horowitz-Strominger Dilaton black hole on the membrane is studied. Owing to the coupling among electromagnetic field, matter field and gravity field, the Dirac equation of charged particles is introduced, and according to that, the expected emission temperature is obtained. After the self-gravitational interaction is considered, it is found that the tunneling rate of fermions also satisfies the underlying Unitary theory as the case of scalar particles.
Geometric Representation of Interacting Non-Relativistic Open Strings using Extended Objects
Arias, P J; Fuenmayor, E; Leal, L
2013-01-01
Non-relativistic charged open strings coupled with Abelian gauge fields are quantized in a geometric representation that generalizes the Loop Representation. The model consists of open-strings interacting through a Kalb-Ramond field in four dimensions. The geometric representation proposed uses lines and surfaces that can be interpreted as an extension of the picture of Faraday's lines of classical electromagnetism. This representation results to be consistent, provided the coupling constant (the "charge" of the string) is quantized. The Schr\\"odinger equation in this representation is also presented.
Fermion masses from dimensional reduction
Energy Technology Data Exchange (ETDEWEB)
Kapetanakis, D. (National Research Centre for the Physical Sciences Democritos, Athens (Greece)); Zoupanos, G. (European Organization for Nuclear Research, Geneva (Switzerland))
1990-10-11
We consider the fermion masses in gauge theories obtained from ten dimensions through dimensional reduction on coset spaces. We calculate the general fermion mass matrix and we apply the mass formula in illustrative examples. (orig.).
Novel fat-link fermion actions
Zanotti, J M; Bonnet, F D R; Coddington, P D; Leinweber, D B; Williams, A G; Zhang, J B; Melnitchouk, W; Lee, F X
2002-01-01
The hadron mass spectrum is calculated in lattice QCD using a novel fat-link clover fermion action in which only the irrelevant operators of the fermion action are constructed using smeared links. The simulations are performed on a 16^3 X 32 lattice with a lattice spacing of a=0.125 fm. We compare actions with n=4 and 12 smearing sweeps with a smearing fraction of 0.7. The n=4 Fat Link Irrelevant Clover (FLIC) action provides scaling which is superior to mean-field improvement, and offers advantages over nonperturbative O(a) improvement.
Wilson Fermions on a Randomly Triangulated Manifold
Burda, Z; Krzywicki, A
1999-01-01
A general method of constructing the Dirac operator for a randomly triangulated manifold is proposed. The fermion field and the spin connection live, respectively, on the nodes and on the links of the corresponding dual graph. The construction is carried out explicitly in 2-d, on an arbitrary orientable manifold without boundary. It can be easily converted into a computer code. The equivalence, on a sphere, of Majorana fermions and Ising spins in 2-d is rederived. The method can, in principle, be extended to higher dimensions.
Fermionic wigs for BTZ black holes
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, Padova 35131 (Italy); INFN, Sezione di Padova, via Marzolo, 8, Padova 35131 (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); Mezzalira, A., E-mail: mezzalir@to.infn.it [Dipartimento di Fisica Teorica, Università di Torino, via P. Giuria, 1, Torino 10125 (Italy); INFN, Gruppo Collegato di Alessandria, Sezione di Torino (Italy)
2013-06-11
We compute the wig for the BTZ black hole, namely the complete non-linear solution of supergravity equations with all fermionic zero modes. We use a “gauge completion” method starting from AdS{sub 3} Killing spinors to generate the gravitinos fields associated to the BH and we compute the back-reaction on the metric. Due to the anticommutative properties of the fermionic hairs the resummation of these effects truncates at some order. We illustrate the technique proposed in a precedent paper in a very explicit and analytical form. We also compute the mass, the angular momentum and other charges with their corrections.
Landau-Lifshitz sigma-models, fermions and the AdS/CFT correspondence
Stefanski, B
2007-01-01
We define Landau-Lifshitz sigma models on general coset space $G/H$, with $H$ a maximal stability sub-group of $G$. These are non-relativistic models that have $G$-valued N\\"other charges, local $H$ invariance and are classically integrable. Using this definition, we construct the $PSU(2,2|4)/PS(U(2|2)^2)$ Landau-Lifshitz sigma-model. This sigma model describes the thermodynamic limit of the spin-chain Hamiltonian obtained from the complete one-loop dilatation operator of the N=4 super Yang-Mills (SYM) theory. In the second part of the paper, we identify a number of consistent truncations of the Type IIB Green-Schwarz action on $AdS_5\\times S^5$ whose field content consists of two real bosons and 4,8 or 16 real fermions. We show that $\\kappa$-symmetry acts trivially in these sub-sectors. In the context of the large spin limit of the AdS/CFT correspondence, we map the Lagrangians of these sub-sectors to corresponding truncations of the $PSU(2,2|4)/PS(U(2|2)^2)$ Landau-Lifshitz sigma-model.
$D$-dimensions Dirac fermions BEC-BCS cross-over thermodynamics with Lorentz violation
Chen, J
2006-01-01
An analytical attempt is made with an effective Proca Lagrangian action to address the vector condensation Lorentz violation effects on the equation of state of strongly interacting fermions. The in-medium many-body renormalization effect is introduced as an external field approximation through a fictive generalized Thomson Problem background. The expressions for the $d$-dimensions thermodynamics are given with finite $S$-wave scattering length. In the non-relativistic limit for $d=3$, universal coefficient $\\xi ={4/9}$ and energy gap $\\Delta ={5/18}\\epsilon_f $ are reasonably consistent with the existed theoretical and experimental results. In the unitary limit for $d=2$ and T=0, the universal dimensionless coefficient can even approach the extreme occasion $\\xi=0$ corresponding to $m^*=\\infty$ which can be mapped to the strongly coupled two-dimensions electrons and is quite similar to the 3-dimensions Bose-Einstein Condensation of ideal boson gas. Instead, for $d=1$, the universal coefficient $\\xi$ is negat...
Vacuum polarization and chiral lattice fermions
Randjbar-Daemi, S.; Strathdee, J.
1996-02-01
The vacuum polarization due to chiral fermions on a 4-dimensional Euclidean lattice is calculated according to the overlap prescription. The fermions are coupled to weak and slowly varying background gauge and Higgs fields, and the polarization tensor is given by second order perturbation theory. In this order the overlap constitutes a gauge-invariant regularization of the fermion vacuum amplitude. Its low-energy-long-wavelength behaviour can be computed explicitly and we verify that it coincides with the Feynman graph result obtainable, for example, by dimensional regularization of continuum gauge theory. In particular, the Standard Model Callan-Symanzik RG functions are recovered. Moreover, there are no residual lattice artefacts such as a dependence on Wilson-type mass parameters.
Vacuum polarization and chiral lattice fermions
Strathdee, J A
1995-01-01
The vacuum polarization due to chiral fermions on a 4--dimensional Euclidean lattice is calculated according to the overlap prescription. The fermions are coupled to weak and slowly varying background gauge and Higgs fields, and the polarization tensor is given by second order perturbation theory. In this order the overlap constitutes a gauge invariant regularization of the fermion vacuum amplitude. Its low energy -- long wavelength behaviour can be computed explicitly and we verify that it coincides with the Feynman graph result obtainable, for example, by dimensional regularization of continuum gauge theory. In particular, the Standard Model Callan--Symanzik RG functions are recovered. Moreover, there are no residual lattice artefacts such as a dependence on Wilson--type mass parameters.
Induced Rigid String Action From Fermions
Parthasarathy, R
1999-01-01
From the Dirac action on the world sheet, an effective action is obtained by integrating over the 4-dimensional fermion fields pulled back to the world sheet. This action consists of the Nambu-Goto area term with right dimensionful constant in front, extrinsic curvature action and the topological Euler characteristic term.
Finite volume renormalization scheme for fermionic operators
Energy Technology Data Exchange (ETDEWEB)
Monahan, Christopher; Orginos, Kostas [JLAB
2013-11-01
We propose a new finite volume renormalization scheme. Our scheme is based on the Gradient Flow applied to both fermion and gauge fields and, much like the Schr\\"odinger functional method, allows for a nonperturbative determination of the scale dependence of operators using a step-scaling approach. We give some preliminary results for the pseudo-scalar density in the quenched approximation.
Strongly interacting two-dimensional Dirac fermions
Lim, L.K.; Lazarides, A.; Hemmerich, Andreas; de Morais Smith, C.
2009-01-01
We show how strongly interacting two-dimensional Dirac fermions can be realized with ultracold atoms in a two-dimensional optical square lattice with an experimentally realistic, inherent gauge field, which breaks time reversal and inversion symmetries. We find remarkable phenomena in a temperature
Fermionization in an Arbitrary Number of Dimensions
Borstnik, N S Mankoc
2016-01-01
One purpose of this proceedings-contribution is to show that at least for free massless particles it is possible to construct an explicit boson theory which is exactly equivalent in terms of momenta and energy to a fermion theory. The fermions come as $2^{d/2-1}$ families and the to this whole system of fermions corresponding bosons come as a whole series of the Kalb-Ramond fields, one set of components for each number of indexes on the tensor fields. Since Kalb-Ramond fields naturally (only) couple to the extended objects or branes, we suspect that inclusion of interaction into such for a bosonization prepared system - except for the lowest dimensions - without including branes or something like that is not likely to be possible. The need for the families is easily seen just by using the theorem long ago put forward by Aratyn and one of us (H.B.F.N.), which says that to have the statistical mechanics of the fermion system and the boson system to match one needs to have the number of the field components in t...
Emergent Lorentz invariance in fermion sector
Directory of Open Access Journals (Sweden)
Kharuk Ivan
2016-01-01
Full Text Available By using holographic description of strongly interacting field theories we show that under common assumptions Lorentz invariance emerges as an effective low–energy symmetry of the theory, despite fundamental theory at hight energies being Lorentz–violating. We consider fermions sector and show that the notion of chirality also automatically arises in the infrared.
Covariant derivative of fermions and all that
Shapiro, Ilya L
2016-01-01
We present detailed pedagogical derivation of covariant derivative of fermions and some related expressions, including commutator of covariant derivatives and energy-momentum tensor of a free Dirac field. The text represents a part of the initial chapter of a one-semester course on semiclassical gravity.
Nonrelativistic factorizable scattering theory of multicomponent Calogero-Sutherland model
Ahn, C; Nam, S; Ahn, Changrim; Lee, Kong Ju Bock; Nam, Soonkeon
1995-01-01
We relate two integrable models in (1+1) dimensions, namely, multicomponent Calogero-Sutherland model with particles and antiparticles interacting via the hyperbolic potential and the nonrelativistic factorizable S-matrix theory with SU(N)-invariance. We find complete solutions of the Yang-Baxter equations without implementing the crossing symmetry, and one of them is identified with the scattering amplitudes derived from the Schr\\"{o}dinger equation of the Calogero-Sutherland model. This particular solution is of interest in that it cannot be obtained as a nonrelativistic limit of any known relativistic solutions of the SU(N)-invariant Yang-Baxter equations.
On the Failure of Multiconfiguration Methods in the Nonrelativistic Limit
Esteban, Maria J; Savin, Andreas
2009-01-01
The multiconfiguration Dirac-Fock method allows to calculate the state of relativistic electrons in atoms or molecules. This method has been known for a long time to provide certain wrong predictions in the nonrelativistic limit. We study in full mathematical details the nonlinear model obtained in the nonrelativistic limit for Be-like atoms. We show that the method with sp+pd configurations in the J=1 sector leads to a symmetry breaking phenomenon in the sense that the ground state is never an eigenvector of L^2 or S^2. We thereby complement and clarify some previous studies.
Tsekov, R
2016-01-01
Thermodynamically, bosons and fermions differ by their statistics only. A general entropy functional is proposed by superposition of entropic terms, typical for different quantum gases. The statistical properties of the corresponding Janus particles are derived by variation of the weight of the boson/fermion fraction. It is shown that di-bosons and anti-fermions separate in gas and liquid phases, while three-phase equilibrium appears for poly-boson/fermion Janus particles.
Grand Unification and Exotic Fermions
Feger, Robert P
2015-01-01
We exploit the recently developed software package LieART to show that SU(N) grand unified theories with chiral fermions in mixed tensor irreducible representations can lead to standard model chiral fermions without additional light exotic chiral fermions, i.e., only standard model fermions are light in these models. Results are tabulated which may be of use to model builders in the future. An SU(6) toy model is given and model searches are discussed.
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.
Fermions from classical statistics
2010-01-01
We describe fermions in terms of a classical statistical ensemble. The states $\\tau$ of this ensemble are characterized by a sequence of values one or zero or a corresponding set of two-level observables. Every classical probability distribution can be associated to a quantum state for fermions. If the time evolution of the classical probabilities $p_\\tau$ amounts to a rotation of the wave function $q_\\tau(t)=\\pm \\sqrt{p_\\tau(t)}$, we infer the unitary time evolution of a quantum system of fe...
Chiral fermions on the lattice
Jahn, O; Jahn, Oliver; Pawlowski, Jan M.
2002-01-01
We discuss topological obstructions to putting chiral fermions on an even dimensional lattice. The setting includes Ginsparg-Wilson fermions, but is more general. We prove a theorem which relates the total chirality to the difference of generalised winding numbers of chiral projection operators. For an odd number of Weyl fermions this implies that particles and anti-particles live in topologically different spaces.
Topological susceptibility from overlap fermion
Institute of Scientific and Technical Information of China (English)
应和平; 张剑波
2003-01-01
We numerically calculate the topological charge of the gauge configurations on a finite lattice by the fermionic method with overlap fermions. By using the lattice index theorem, we identify the index of the massless overlap fermion operator to the topological charge of the background gauge configuration. The resulting topological susceptibility X is in good agreement with the anticipation made by Witten and Veneziano.
Fermion Delocalization in Higgsless Models
De Curtis, S
2005-01-01
In the linear moose framework, which naturally emerges in deconstruction models, we discuss the effect of direct couplings between the left-handed fermions living on the boundary of the chain and the gauge fields in the internal sites. This is realized by means of a product of nonlinear sigma-model scalar fields which, in the continuum limit, is equivalent to a Wilson line. The effect of these new nonlocal couplings is a contribution to the S parameter which can be of opposite sign with respect to the one coming from the gauge fields along the string. Therefore, with some fine-tuning, it is possible to satisfy the constraints from the electro-weak data without spoiling the perturbative unitarity limit, which, in these models is generally postponed with respect to the Higgsless Standard Model one.
Non-relativistic anyons from holography
Directory of Open Access Journals (Sweden)
Niko Jokela
2017-03-01
Full Text Available We study generic types of holographic matter residing in Lifshitz invariant defect field theory as modeled by adding probe D-branes in the bulk black hole spacetime characterized by dynamical exponent z and with hyperscaling violation exponent θ. Our main focus will be on the collective excitations of the dense matter in the presence of an external magnetic field. Constraining the defect field theory to 2+1 dimensions, we will also allow the gauge fields become dynamical and study the properties of a strongly coupled anyonic fluid. We will deduce the universal properties of holographic matter and show that the Einstein relation always holds.
Hybrid Monte Carlo with Fat Link Fermion Actions
Kamleh, W; Williams, A G; Kamleh, Waseem; Leinweber, Derek B.; Williams, Anthony G.
2004-01-01
The use of APE smearing or other blocking techniques in lattice fermion actions can provide many advantages. There are many variants of these fat link actions in lattice QCD currently, such as FLIC fermions. The FLIC fermion formalism makes use of the APE blocking technique in combination with a projection of the blocked links back into the special unitary group. This reunitarisation is often performed using an iterative maximisation of a gauge invariant measure. This technique is not differentiable with respect to the gauge field and thus prevents the use of standard Hybrid Monte Carlo simulation algorithms. The use of an alternative projection technique circumvents this difficulty and allows the simulation of dynamical fat link fermions with standard HMC and its variants. The necessary equations of motion for FLIC fermions are derived, and some initial simulation results are presented. The technique is more general however, and is straightforwardly applicable to other smearing techniques or fat link actions...
Hybrid Monte Carlo algorithm with fat link fermion actions
Kamleh, Waseem; Williams, Anthony G; 10.1103/PhysRevD.70.014502
2004-01-01
The use of APE smearing or other blocking techniques in lattice fermion actions can provide many advantages. There are many variants of these fat link actions in lattice QCD currently, such as flat link irrelevant clover (FLIC) fermions. The FLIC fermion formalism makes use of the APE blocking technique in combination with a projection of the blocked links back into the special unitary group. This reunitarization is often performed using an iterative maximization of a gauge invariant measure. This technique is not differentiable with respect to the gauge field and thus prevents the use of standard Hybrid Monte Carlo simulation algorithms. The use of an alternative projection technique circumvents this difficulty and allows the simulation of dynamical fat link fermions with standard HMC and its variants. The necessary equations of motion for FLIC fermions are derived, and some initial simulation results are presented. The technique is more general however, and is straightforwardly applicable to other smearing ...
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.
Boundary effects and gapped dispersion in rotating fermionic matter
Ebihara, Shu; Mameda, Kazuya
2016-01-01
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.
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.
Boundary effects and gapped dispersion in rotating fermionic matter
Ebihara, Shu; Fukushima, Kenji; Mameda, Kazuya
2017-01-01
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.
Combescure, Monique; Robert, Didier
2012-06-01
The aim of this paper is to give a self-contained and unified presentation of a fermionic coherent state theory with the necessary mathematical details, discussing their definition, properties and some applications. After defining Grassmann algebras, it is possible to get a classical analog for the fermionic degrees of freedom in a quantum system. Following the basic work of Berezin (1966 The Method of Second Quantization (New York: Academic); 1987 Introduction to Superanalysis (Dordrecht: Reidel Publishing Company)), we show that we can compute with Grassmann numbers as we do with complex numbers: derivation, integration, Fourier transform. After that we show that we have quantization formulas for fermionic observables. In particular, there exists a Moyal product formula. As an application, we consider explicit computations for propagators with quadratic Hamiltonians in annihilation and creation operators. We prove a Mehler formula for the propagator and Mehlig-Wilkinson-type formulas for the covariant and contravariant symbols of ‘metaplectic’ transformations for fermionic states. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’.
Cabra, D C; Cabra, Daniel C; Rossini, Gerardo L
1996-01-01
We give an explicit holomorphic factorization of SU(N)_1 WZW primaries in terms of gauge invariant composite fermions. In the N=2 case, we show that these composites realize the spinon algebra. Both in this and in the general case, the underlying Yangian symmetry implies that these operators span the whole Fock space.
Relative weights approach to dynamical fermions at finite densities
Greensite, Jeff
2016-01-01
The method of relative weights, coupled with mean field theory, is applied to the problem of simulating gauge theories with dynamical staggered fermions at finite densities. We present initial results and discuss issues so far encountered.
Non-relativistic supergravity in three space-time dimensions
Zojer, Thomas
2016-01-01
This year Einstein's theory of general relativity celebrates its one hundredth birthday. It supersedes the non-relativistic Newtonian theory of gravity in two aspects: i) there is a limiting velocity, nothing can move quicker than the speed of light and ii) the theory is valid in arbitrary coordinat
A brief introduction to non-relativistic supergravity
Energy Technology Data Exchange (ETDEWEB)
Zojer, Thomas [Van Swinderen Institute for Particle Physics and Gravity, University of Groningen (Netherlands)
2016-04-15
Non-relativistic geometries have received more attention lately. We review our attempts to construct supersymmetric extensions of this so-called Newton-Cartan geometry in three space-time dimensions. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Non-relativistic supergravity in three space-time dimensions
Zojer, Thomas
2016-01-01
This year Einstein's theory of general relativity celebrates its one hundredth birthday. It supersedes the non-relativistic Newtonian theory of gravity in two aspects: i) there is a limiting velocity, nothing can move quicker than the speed of light and ii) the theory is valid in arbitrary
Non-relativistic classical mechanics for spinning particles
Salesi, G
2004-01-01
We study the classical dynamics of non-relativistic particles endowed with spin. Non-vanishing Zitterbewegung terms appear in the equation of motion also in the small momentum limit. We derive a generalized work-energy theorem which suggests classical interpretations for tunnel effect and quantum potential.
Theory of non-relativistic three-particle scattering
Malfliet, R.; Ruijgrok, Th.
1967-01-01
A new method, using asymptotically stationary states, is developed to calculate the S-matrix for the scattering of a non-relativistic particle by the bound state of two other particles. For the scattering with breakup of this bound state, we obtain a simplified form of the Faddeev integral
Al-Hashimi, M H; Wiese, U -J
2016-01-01
Majorana fermion dynamics may arise at the edge of Kitaev wires or superconductors. Alternatively, it can be engineered by using trapped ions or ultracold atoms in an optical lattice as quantum simulators. This motivates the theoretical study of Majorana fermions confined to a finite volume, whose boundary conditions are characterized by self-adjoint extension parameters. While the boundary conditions for Dirac fermions in $(1+1)$-d are characterized by a 1-parameter family, $\\lambda = - \\lambda^*$, of self-adjoint extensions, for Majorana fermions $\\lambda$ is restricted to $\\pm i$. Based on this result, we compute the frequency spectrum of Majorana fermions confined to a 1-d interval. The boundary conditions for Dirac fermions confined to a 3-d region of space are characterized by a 4-parameter family of self-adjoint extensions, which is reduced to two distinct 1-parameter families for Majorana fermions. We also consider the problems related to the quantum mechanical interpretation of the Majorana equation ...
Effective and fundamental quantum fields at criticality
Energy Technology Data Exchange (ETDEWEB)
Scherer, Michael
2010-10-28
We employ Wetterich's approach to functional renormalization as a suitable method to investigate universal phenomena in non-perturbative quantum field theories both qualitatively and quantitatively. Therefore we derive and investigate flow equations for a class of chiral Yukawa models with and without gauge bosons and reveal fixed-point mechanisms. In four dimensions chiral Yukawa systems serve as toy models for the standard model Higgs sector and show signatures of asymptotically safe fixed points by a balancing of bosonic and fermionic contributions. In the approximations investigated this renders the theory fundamental and solves the triviality problem. Further, we obtain predictions for the Higgs mass and even for the top mass of our toy model. In three dimensions we compute the critical exponents which define new universality classes and provide benchmark values for systems of strongly correlated chiral fermions. In a Yukawa system of non-relativistic two-component fermions a fixed point dominates the renormalization flow giving rise to universality in the BCS-BEC crossover. We push the functional renormalization method to a quantitative level and we compute the critical temperature and the single-particle gap with a considerable precision for the whole crossover. Finally, we provide further evidence for the asymptotic safety scenario in quantum gravity by confirming the existence of an ultraviolet fixed point under inclusion of a curvature-ghost coupling. (orig.)
Nonrelativistic gauged quantum mechanics: From Kaluza–Klein compactifications to Bargmann structures
Energy Technology Data Exchange (ETDEWEB)
Bargueño, Pedro, E-mail: p.bargueno@uniandes.edu.co
2015-08-14
Highlights: • Null compactification techniques are used to derive the nonrelativistic gauged Schrödinger equation. • Compactification of both Klein–Gordon and Maxwell theories are revisited. • Connections with Kaluza–Klein-like Bargmann frameworks are established. - Abstract: The Schrödinger equation for a spinless particle in presence of an external electromagnetic field is derived by means of null compactification of five dimensional massless Klein–Gordon theory and five–dimensional Maxwell electrodynamics. Connections with Kaluza–Klein-like Bargmann frameworks are established.
Nonrelativistic limit of the abelianized ABJM model and the ADS/CMT correspondence
Lopez-Arcos, Cristhiam; Murugan, Jeff; Nastase, Horatiu
2016-05-01
We consider the nonrelativistic limit of the abelian reduction of the massive ABJM model proposed in [1], obtaining a supersymmetric version of the Jackiw-Pi model. The system exhibits an mathcal{N}=2 Super-Schrödinger symmetry with the Jackiw-Pi vortices emerging as BPS solutions. We find that this (2 + 1)-dimensional abelian field theory is dual to a certain (3+1)-dimensional gravity theory that differs somewhat from previously considered abelian condensed matter stand-ins for the ABJM model. We close by commenting on progress in the top-down realization of the AdS/CMT correspondence in a critical string theory.
Maxwell-Chern-Simons Models: Their Symmetries, Exact Solutions and Non-relativistic Limits
Directory of Open Access Journals (Sweden)
J. Niederle
2010-01-01
Full Text Available Two Maxwell-Chern-Simons (MCS models in the (1 + 3-dimensional space-space are discussed and families of their exact solutions are found. In contrast to the Carroll-Field-Jackiw (CFE model [2] these systems are relativistically invariant and include the CFJ model as a particular sector.Using the InNonNu-Wigner contraction a Galilei-invariant non-relativistic limit of the systems is found, which makes possible to find a Galilean formulation of the CFJ model.
Flavor Constraints on Split Fermion Models
Energy Technology Data Exchange (ETDEWEB)
Lillie, Ben
2003-06-26
We examine the contributions to rare processes that arise in models where the Standard Model fermions are localized at distinct points in compact extra dimensions. Tree-level flavor changing neutral current interactions for the Kaluza-Klein (KK) gauge field excitations are induced in such models, and hence strong constraints are thought to exist on the size of the additional dimensions. We find a general parameterization of the model which does not depend on any specific fermion geography and show that typical values of the parameters can reproduce the fermion hierarchy pattern. Using this parameterization, we reexamine the contributions to neutral meson mixing, rare meson decays, and single top-quark production in e{sup +}e{sup -} collisions. We find that is it possible to evade the stringent bounds for natural regions of the parameters, while retaining finite separations between the fermion fields and without introducing a new hierarchy. The resulting limits on the size of the compact dimension can be as low as TeV{sup -1}.
Flavor Constraints on Split Fermion Models
Lillie, Benjamin Huntington; Lillie, Ben; Hewett, JoAnne
2003-01-01
We examine the contributions to rare processes that arise in models where the Standard Model fermions are localized at distinct points in compact extra dimensions. Tree-level flavor changing neutral current interactions for the Kaluza-Klein (KK) gauge field excitations are induced in such models, and hence strong constraints are thought to exist on the size of the additional dimensions. We find a general parameterization of the model which does not depend on any specific fermion geography and show that typical values of the parameters can reproduce the fermion hierarchy pattern. Using this parameterization, we reexamine the contributions to neutral meson mixing, rare meson decays, and single top-quark production in $e^+e^-$ collisions. We find that is it possible to evade the stringent bounds for natural regions of the parameters, while retaining finite separations between the fermion fields and without introducing a new hierarchy. The resulting limits on the size of the compact dimension can be as low as TeV...
Virial Theorem for Nonrelativistic Quantum Fields in D Spatial Dimensions
Directory of Open Access Journals (Sweden)
Chris L. Lin
2015-01-01
appearance of a Jacobian J due to a change of variables in the path-integral expression for the partition function of the system is pointed out, although in order to make contact with the literature most of the analysis deals with the J=1 case. The virial theorem is recast into a form that displays the effect of microscopic scales on the thermodynamics of the system. From the point of view of this paper the case usually considered, J=1, is not natural, and the generalization to the case J≠1 is briefly presented.
Numerical properties of staggered overlap fermions
de Forcrand, Philippe; Panero, Marco
2010-01-01
We report the results of a numerical study of staggered overlap fermions, following the construction of Adams which reduces the number of tastes from 4 to 2 without fine-tuning. We study the sensitivity of the operator to the topology of the gauge field, its locality and its robustness to fluctuations of the gauge field. We make a first estimate of the computing cost of a quark propagator calculation, and compare with Neuberger's overlap.
Majorana fermions coupled to electromagnetic radiation
Ohm, Christoph; Hassler, Fabian
2013-01-01
We consider a voltage-biased Josephson junction between two nanowires hosting Majorana zero modes which occur as topological protected zero-energy excitations at the junction. We show that two Majorana fermions localized at the junction, even though being neutral particles, interact with the electromagnetic field and generate coherent radiation similar to the conventional Josephson radiation. Within a semiclassical analysis of the radiation field, we find that the optical phase gets locked to...
SU(8) Family Unification with Boson Fermion Balance
Adler, Stephen L.
2015-03-01
We formulate an SU(8) family unification model motivated by requiring that the theory should incorporate the graviton, gravitinos, and the fermions and gauge fields of the standard model, with boson.fermion balance. Gauge field SU(8) anomalies cancel between the gravitinos and spin 1/2 fermions. The 56 of scalars breaks SU(8) to SU(3)family×SU(5)×U(1)/Z5, with the fermion representation content needed for "flipped" SU(5) with three families, and with residual scalars in the 10 and overline {10} representations that break flipped SU(5) to the standard model. Dynamical symmetry breaking can account for the generation of 5 representation scalars needed to break the electroweak group. Yukawa couplings of the 56 scalars to the fermions are forbidden by chiral and gauge symmetries, so in the first stage of SU(8) breaking fermions remain massless. In the limit of vanishing gauge coupling, there are N = 1 and N = 8 supersymmetries relating the scalars to the fermions, which restrict the form of scalar self-couplings and should improve the convergence of perturbation theory, if not making the theory finite and "calculable." In an Appendix we give an analysis of symmetry breaking by a Higgs component, such as the (1, 1)(-15) of the SU(8) 56 under SU(8) ⊃ SU(3) × SU(5) × U(1), which has nonzero U(1) generator.
Relativistic and non-relativistic solitons in plasmas
Barman, Satyendra Nath
This thesis entitled as "Relativistic and Non-relativistic Solitons in Plasmas" is the embodiment of a number of investigations related to the formation of ion-acoustic solitary waves in plasmas under various physical situations. The whole work of the thesis is devoted to the studies of solitary waves in cold and warm collisionless magnetized or unmagnetized plasmas with or without relativistic effect. To analyze the formation of solitary waves in all our models of plasmas, we have employed two established methods namely - reductive perturbation method to deduce the Korteweg-de Vries (KdV) equation, the solutions of which represent the important but near exact characteristic concepts of soliton-physics. Next, the pseudopotential method to deduce the energy integral with total nonlinearity in the coupling process for exact characteristic results of solitons has been incorporated. In Chapter 1, a brief description of plasma in nature and laboratory and its generation are outlined elegantly. The nonlinear differential equations to characterize solitary waves and the relevant but important methods of solutions have been mentioned in this chapter. The formation of solitary waves in unmagnetized and magnetized plasmas, and in relativistic plasmas has been described through mathematical entity. Applications of plasmas in different fields are also put forwarded briefly showing its importance. The study of plasmas as they naturally occur in the universe encompasses number of topics including sun's corona, solar wind, planetary magnetospheres, ionospheres, auroras, cosmic rays and radiation. The study of space weather to understand the universe, communications and the activities of weather satellites are some useful areas of space plasma physics. The surface cleaning, sterilization of food and medical appliances, killing of bacteria on various surfaces, destroying of viruses, fungi, spores and plasma coating in industrial instruments ( like computers) are some of the fields
Harada, Koji; Yoshimoto, Issei
2012-01-01
Low-energy effective field theory describing a nonrelativistic three-body system is analyzed in the Wilsonian renormalization group (RG) method. No effective auxiliary field (dimeron) that corresponds to two-body propagation is introduced. The Efimov effect is expected in the case of an infinite two-body scattering length, and is believed to be related to the limit cycle behavior in the three-body renormalization group equations (RGEs). If the one-loop property of the RGEs for the nonrelativistic system without the dimeron field, which is essential in deriving RGEs in the two-body sector, persists in the three-body sector, it appears to prevent the emergence of limit cycle behavior. We explain how the multi-loop diagrams contribute in the three-body sector without contradicting the one-loop property of the RGEs, and derive the correct RGEs, which lead to the limit cycle behavior. The Efimov parameter, $s_{0}$, is obtained within a few percent error in the leading orders. We also remark on the correct use of t...
Holomorphic Symplectic Fermions
Davydov, Alexei
2016-01-01
Let V be the even part of the vertex operator super-algebra of r pairs of symplectic fermions. Up to two conjectures, we show that V admits a unique holomorphic extension if r is a multiple of 8, and no holomorphic extension otherwise. This is implied by two results obtained in this paper: 1) If r is a multiple of 8, one possible holomorphic extension is given by the lattice vertex operator algebra for the even self dual lattice $D_r^+$ with shifted stress tensor. 2) We classify Lagrangian algebras in SF(h), a ribbon category associated to symplectic fermions. The classification of holomorphic extensions of V follows from 1) and 2) if one assumes that SF(h) is ribbon equivalent to Rep(V), and that simple modules of extensions of V are in one-to-one relation with simple local modules of the corresponding commutative algebra in SF(h).
Agrawal, Jyoti; Frampton, Paul H.; Jack Ng, Y.; Nishino, Hitoshi; Yasuda, Osamu
1991-03-01
An extension of the standard model is proposed. The gauge group is SU(2) X ⊗ SU(3) C ⊗ SU(2) S ⊗ U(1) Q, where all gauge symmetries are unbroken. The colour and electric charge are combined with SU(2) S which becomes strongly coupled at approximately 500 GeV and binds preons to form fermionic and vector bound states. The usual quarks and leptons are singlets under SU(2) X but additional fermions, called sarks. transform under it and the electroweak group. The present model explains why no more than three light quark-lepton families can exist. Neutral sark baryons, called narks, are candidates for the cosmological dark matter having the characteristics designed for WIMPS. Further phenomenological implications of sarks are analyzed i including electron-positron annihilation. Z 0 decay, flavor-changing neutral currents. baryon-number non-conservation, sarkonium and the neutron electric dipole moment.
Leptogenesis from split fermions
Energy Technology Data Exchange (ETDEWEB)
Nagatani, Yukinori; Perez, Gilad
2004-01-11
We present a new type of leptogenesis mechanism based on a two-scalar split-fermions framework. At high temperatures the bulk scalar vacuum expectation values (VEVs) vanish and lepton number is strongly violated. Below some temperature, T{sub c}, the scalars develop extra dimension dependent VEVs. This transition is assumed to proceed via a first order phase transition. In the broken phase the fermions are localized and lepton number violation is negligible. The lepton-bulk scalar Yukawa couplings contain sizable CP phases which induce lepton production near the interface between the two phases. We provide a qualitative estimation of the resultant baryon asymmetry which agrees with current observation. The neutrino flavor parameters are accounted for by the above model with an additional approximate U(1) symmetry.
Chavanis, Pierre-Henri; Méhats, Florian
2014-01-01
We study the fermionic King model which may provide a relevant model of dark matter halos. The exclusion constraint can be due to quantum mechanics (for fermions such as massive neutrinos) or to Lynden-Bell's statistics (for collisionless systems undergoing violent relaxation). This model has a finite mass. Furthermore, a statistical equilibrium state exists for all accessible values of energy. Dwarf and intermediate size halos are degenerate quantum objects stabilized against gravitational collapse by the Pauli exclusion principle. Large halos at sufficiently high energies are in a gaseous phase where quantum effects are negligible. They are stabilized by thermal motion. Below a critical energy they undergo gravitational collapse (gravothermal catastrophe). This may lead to the formation of a central black hole that does not affect the structure of the halo. This may also lead to the formation of a compact degenerate object surrounded by a hot massive atmosphere extending at large distances. We argue that la...
Lin, De-Hone
2015-01-01
This paper is concerned with the application of a spacetime structure to a three-dimensional quantum system. There are three components. First, the main part of this paper presents the constraint conditions which build the relation of a spacetime structure and a form invariance solution to the covariant Dirac equation. The second is to devise a spacetime cage for fermions with chosen constraints. The third part discusses the feasibility of the cage with an experiment.
Playing with fermion couplings in Higgsless models
Casalbuoni, R; Dolce, D; Dominici, Daniele
2005-01-01
We discuss the fermion couplings in a four dimensional SU(2) linear moose model by allowing for direct couplings between the left-handed fermions on the boundary and the gauge fields in the internal sites. This is realized by means of a product of non linear $\\sigma$-model scalar fields which, in the continuum limit, is equivalent to a Wilson line. The effect of these new non local couplings is a contribution to the $\\epsilon_3$ parameter which can be of opposite sign with respect to the one coming from the gauge fields along the string. Therefore, with some fine tuning, it is possible to satisfy the constraints from the electroweak data.
Tripartite composite fermion states
Sreejith, G. J.; Wu, Ying-Hai; Wójs, A.; Jain, J. K.
2013-06-01
The Read-Rezayi wave function is one of the candidates for the fractional quantum Hall effect at filling fraction ν=2+⅗, and thereby also its hole conjugate at 2+⅖. We study a general class of tripartite composite fermion wave functions, which reduce to the Rezayi-Read ground state and quasiholes for appropriate quantum numbers, but also allow a construction of wave functions for quasiparticles and neutral excitations by analogy to the standard composite fermion theory. We present numerical evidence in finite systems that these trial wave functions capture well the low energy physics of a four-body model interaction. We also compare the tripartite composite fermion wave functions with the exact Coulomb eigenstates at 2+⅗, and find reasonably good agreement. The ground state as well as several excited states of the four-body interaction are seen to evolve adiabatically into the corresponding Coulomb states for N=15 particles. These results support the plausibility of the Read-Rezayi proposal for the 2+⅖ and 2+⅗ fractional quantum Hall effect. However, certain other proposals also remain viable, and further study of excitations and edge states will be necessary for a decisive establishment of the physical mechanism of these fractional quantum Hall states.
Topology and Fermionic Condensate
Kulikov, I.; Pronin, P.
The purpose of this paper is to investigate an influence of a space-time topology on the formation of fermionic condensate in the model with four-fermion interaction ()2. The value for the space-time with topology of R1 × R1 × S1 is found. Moreover a relation of the value of fermionic condensate to a periodic length is studied. In this connection the possibility of a relation of the topologic deposits to structure of hadrons is discussed.Translated AbstractTopologie und FermikondensatEs wird der Einfluß einer Raum-Zeittopologie auf die Bildung des Fermikondensats in einem Modell mit Vierfermionenwechselwirkung ()2 untersucht. Für eine Raum-Zeit mit der Topologie R1 × R2 × S1 werden die Parameter gegeben. Weiterhin wird die Relation der Größe des Fermikondensats zu einer periodischen Länge untersucht. In diesem Zusammenhang wird die Verbindung des topologischen Depots zur Struktur der Hadronen diskutiert.
Composite gauge-bosons made of fermions
Suzuki, Mahiko
2016-07-01
We construct a class of Abelian and non-Abelian local gauge theories that consist only of matter fields of fermions. The Lagrangian is local and does not contain an auxiliary vector field nor a subsidiary condition on the matter fields. It does not involve an extra dimension nor supersymmetry. This Lagrangian can be extended to non-Abelian gauge symmetry only in the case of SU(2) doublet matter fields. We carry out an explicit diagrammatic computation in the leading 1 /N order to show that massless spin-one bound states appear with the correct gauge coupling. Our diagram calculation exposes the dynamical features that cannot be seen in the formal auxiliary vector-field method. For instance, it shows that the s -wave fermion-antifermion interaction in the 3S1 channel (ψ ¯ γμψ ) alone cannot form the bound gauge bosons; the fermion-antifermion pairs must couple to the d -wave state too. One feature common to our class of Lagrangian is that the Noether current does not exist. Therefore it evades possible conflict with the no-go theorem of Weinberg and Witten on the formation of the non-Abelian gauge bosons.
Composite gauge-bosons made of fermions
Suzuki, Mahiko
2016-01-01
We construct a class of Abelian and non-Abelian local gauge theories that consist only of matter fields of fermions. The Lagrangian is compact and local without containing an auxiliary vector field nor a subsidiary condition on the matter fields. Because of the special structure, this Lagrangian can be extended to non-Abelian gauge symmetry only in the case of SU(2) doublet matter fields. We carry out explicit dynamical computation in the leading 1/N order to show that massless spin-one bound states appear with the correct gauge coupling. Our diagram calculation exposes the dynamical features that cannot be explored in the formal auxiliary vector-field trick. For instance, it shows that the s-wave fermion-antifermion interaction alone cannot form the bound gauge-bosons; the fermion-antifermion pairs must couple to the d-wave state too. Since our models are unrenormalizable in the world of (3+1) dimension, they can be phenomenologically relevant, if at all, only when momentum cutoff is introduced.
Casimir operator dependences of non-perturbative fermionic QCD amplitudes
Fried, H M; Hofmann, R
2015-01-01
In eikonal and quenched approximation, it is argued that the strong coupling fermionic QCD Green's functions and related amplitudes, when based on the newly discovered effective locality property, depart from a sole dependence on the SUc(3) quadratic Casimir operator, evaluated over the fundamental gauge group representation.Though noticed in non-relativistic Quark Models, an additional dependence on the cubic Casimir operator is in contradistinction with perturbation theory, and also with a number of non-perturbative approaches such as the MIT Bag, the Stochastic Vacuum Models and lattice simulations. It accounts for the full algebraic content of the rank-2 Lie algebra of SUc(3). We briefly discuss the orders of magnitude of quadratic and cubic Casimir operator contributions.
Dense Chern-Simons Matter with Fermions at Large N
Geracie, Michael; Son, Dam T
2015-01-01
In this paper we investigate properties of Chern-Simons theory coupled to massive fermions in the large N limit. We demonstrate that at low temperatures the system is in a Fermi liquid state whose features can be systematically compared to the standard phenomenological theory of Landau Fermi liquids. This includes matching microscopically derived Landau parameters with thermodynamic predictions of Landau Fermi liquid theory. We also calculate the exact conductivity and viscosity tensors at zero temperature and finite chemical potential. In particular we point out that the Hall conductivity of an interacting system is not entirely accounted for by the Berry flux through the Fermi sphere. Furthermore, investigation of the thermodynamics in the non-relativistic limit reveals novel phenomena at strong coupling. As the 't Hooft coupling approaches 1, the system exhibits an extended intermediate temperature regime in which the thermodynamics is described by neither the quantum Fermi liquid theory nor the classical ...
Fermions and the AdS/CFT correspondence: quantum phase transitions and the emergent Fermi-liquid
Cubrovic, Mihailo; Schalm, Koenraad
2009-01-01
A central mystery in quantum condensed matter physics is the zero temperature quantum phase transition between strongly renormalized Fermi-liquids as found in heavy fermion intermetallics and possibly high Tc superconductors. Field theoretical statistical techniques are useless because of the fermion sign problem, but we will present here results showing that the mathematics of string theory is capable of describing fermionic quantum critical states. Using the Anti-de-Sitter/Conformal Field Theory (AdS/CFT) correspondence to relate fermionic quantum critical fields to a gravitational problem, we compute the spectral functions of fermions in the field theory. Deforming away from the relativistic quantum critical point by increasing the fermion density we show that a state emerges with all the features of the Fermi-liquid. Tuning the scaling dimensions of the critical fermion fields we find that the quasiparticle disappears at a quantum phase transition of a purely statistical nature, not involving any symmetry...
Noncommutativity Parameter and Composite Fermions
Jellal, Ahmed
We determine some particular values of the noncommutativity parameter θ and show that the Murthy Shankar approach is in fact a particular case of a more general one. Indeed, using the fractional quantum Hall effect (FQHE) experimental data, we give a measurement of θ. This measurement can be obtained by considering some values of the filling factor ν and other ingredients, magnetic field B and electron density ρ. Moreover, it is found that θ can be quantized either fractionally or integrally in terms of the magnetic length l0 and the quantization is exactly what Murthy and Shankar formulated recently for the FQHE. On the other hand, we show that the mapping of the FQHE in terms of the composite fermion basis has a noncommutative geometry nature and therefore there is a more general way than the Murthy Shankar method to do this mapping.
Gauge invariant Pauli-Villars regularization for chiral fermion
Okuyama, K; Okuyama, Kiyoshi; Suzuki, Hiroshi
1996-01-01
We re-examine the generalized Pauli--Villars regularization proposed by Frolov and Slavnov, a possible gauge invariant Lagrangian-level regularization for a chiral fermion. When a chiral fermion belongs to a (pseudo-)real representation of the gauge group, the formulation always provides a complete gauge invariant regularization; a chiral fermion in an anomaly free complex representation seems to be only partially regularized. For the pseudo-real representation, the formulation requires an infinite number of regulator fields, while for the real representation only a finite number of regulator fields is sufficient. For both cases, being gauge invariant, the regularization gives a transverse vacuum polarization tensor without any gauge variant counter terms. The covariant (or gauge invariant) form of the fermion number and the conformal anomalies are obtained in this regularization.
Non-relativistic twistor theory and Newton--Cartan geometry
Dunajski, Maciej
2015-01-01
We develop a non-relativistic twistor theory, in which Newton--Cartan structures of Newtonian gravity correspond to complex three-manifolds with a four-parameter family of rational curves with normal bundle ${\\mathcal O}\\oplus{\\mathcal O}(2)$. We show that the Newton--Cartan space-times are unstable under the general Kodaira deformation of the twistor complex structure. The Newton--Cartan connections can nevertheless be reconstructed from Merkulov's generalisation of the Kodaira map augmented by a choice of a holomorphic line bundle over the twistor space trivial on twistor lines. The Coriolis force may be incorporated by holomorphic vector bundles, which in general are non--trivial on twistor lines. The resulting geometries agree with non--relativistic limits of anti-self-dual gravitational instantons.
Hadron Properties with FLIC Fermions
Energy Technology Data Exchange (ETDEWEB)
James Zanotti; Wolodymyr Melnitchouk; Anthony Williams; J Zhang
2003-07-01
The Fat-Link Irrelevant Clover (FLIC) fermion action provides a new form of nonperturbative O(a)-improvement in lattice fermion actions offering near continuum results at finite lattice spacing. It provides computationally inexpensive access to the light quark mass regime of QCD where chiral nonanalytic behavior associated with Goldstone bosons is revealed. The motivation and formulation of FLIC fermions, its excellent scaling properties and its low-lying hadron mass phenomenology are presented.
Fermion Tunnelling of a New Form Finslerian Black Hole
Institute of Scientific and Technical Information of China (English)
LIN Kai; YANG Shu-Zheng
2009-01-01
We improve the fermion tunnelling theory proposed by Kerner and Mann, and research into the fermion tunnelling radiation from a Finslerian black hole. The Finsler black hole put forward by Rutz is a solution of Einstein's vacuum field equations in Finsler theory. We study the radiation from the black hole with a semi-classical method, and the result proves that the tunnelling rate depends on the tangent vector.
Observation of three-component fermions in the topological semimetal molybdenum phosphide
Lv, B. Q.; Feng, Z.-L.; Xu, Q.-N.; Gao, X.; Ma, J.-Z.; Kong, L.-Y.; Richard, P.; Huang, Y.-B.; Strocov, V. N.; Fang, C.; Weng, H.-M.; Shi, Y.-G.; Qian, T.; Ding, H.
2017-06-01
In quantum field theory, Lorentz invariance leads to three types of fermion—Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems. The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally, and that of Majorana fermions is supported by various experiments. However, in condensed-matter systems, fermions in crystals are constrained by the symmetries of the 230 crystal space groups rather than by Lorentz invariance, giving rise to the possibility of finding other types of fermionic excitation that have no counterparts in high-energy physics. Here we use angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac-Weyl-Majorana classification, which attributes Dirac and Weyl fermions to four- and two-fold degenerate points, respectively. We also observe pairs of Weyl points in the bulk electronic structure of the crystal that coexist with the three-component fermions. This material thus represents a platform for studying the interplay between different types of fermions. Our experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems.
On free fermions and plane partitions
Foda, O; Zuparic, M
2008-01-01
We use free fermion methods to re-derive a result of Okounkov and Reshetikhin relating charged fermions to random plane partitions, and to extend it to relate neutral fermions to strict plane partitions.
On Fermionic Entangled State Representation and Fermionic Entangled Wigner Operator
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
By analogy with the bosonic bipartite entangled state we construct fermionic entangled state with the Grassmann numbers. The Wigner operator in the fermionic entangled state representation is introduced, whose marginal distributions are understood in an entangled way. The technique of integration within an ordered product (IWOP) of Fermi operators is used in our discussion.
A note on the path integral representation for Majorana fermions
Greco, Andrés
2016-04-01
Majorana fermions are currently of huge interest in the context of nanoscience and condensed matter physics. Different to usual fermions, Majorana fermions have the property that the particle is its own anti-particle thus, they must be described by real fields. Mathematically, this property makes nontrivial the quantization of the problem due, for instance, to the absence of a Wick-like theorem. In view of the present interest on the subject, it is important to develop different theoretical approaches in order to study problems where Majorana fermions are involved. In this note we show that Majorana fermions can be studied in the context of field theories for constrained systems. Using the Faddeev-Jackiw formalism for quantum field theories with constraints, we derived the path integral representation for Majorana fermions. In order to show the validity of the path integral we apply it to an exactly solvable problem. This application also shows that it is rather simple to perform systematic calculations on the basis of the present framework.
Fermionic Optical Lattices: A Computational Study
2014-10-22
Kevin Schmidt, Shiwei Zhang. Auxiliary-field quantum Monte Carlo method for strongly paired fermions, Physical Review A, (12 2011): 0. doi...10.1103/PhysRevA.84.061602 A. Euverte, F. Hébert, S. Chiesa, R. Scalettar, G. Batrouni. Kondo Screening and Magnetism at Interfaces, Physical Review Letters...contact interaction: Magnetic properties in a dilute Hubbard model, Physical Review A, (12 2010): 0. doi: 10.1103/PhysRevA.82.061603 S. Zhou, D
Superpersistent Currents in Dirac Fermion Systems
2017-03-06
TITLE AND SUBTITLE Superpersistent Currents in Dirac Fermion Systems 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-15-1-0151 5c. PROGRAM ELEMENT...currents in 2D Dirac material systems and pertinent phenomena in the emerging field of relativistic quantum nonlinear dynamics and chaos. Systematic...anomalous optical transitions, and spin control in topological insulator quantum dots, (4) the discovery of nonlinear dynamics induced anomalous Hall
Heavy fermion material: Ce versus Yb case
Flouquet, J.; Harima, H.
2009-01-01
Heavy fermion compounds are complex systems but excellent materials to study quantum criticality with the switch of different ground states. Here a special attention is given on the interplay between magnetic and valence instabilities which can be crossed or approached by tuning the system by pressure or magnetic field. By contrast to conventional rare earth magnetism or classical s wave superconductivity, strong couplings may occur with drastic changes in spin or charge dynamics. Measurement...
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.)
The Principle of the Fermionic Projector, Appendices
2002-01-01
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. The book begins with a brief review of relativity, relativistic quantum mechanics and classical gauge theories, with the emphasis on the basic physical concepts and the mathematical foundations. The external field problem and Klein's paradox are discussed and then resolved by introducing the so-called fermi...
Supersymmetry for Fermion Masses
Institute of Scientific and Technical Information of China (English)
LIU Chun
2007-01-01
It is proposed that supersymmetry (SUSY) may be used to understand fermion mass hierarchies. A family symmetry Z3L is introduced, which is the cyclic symmetry among the three generation SU(2) doublets. SUSY breaks at a high energy scale ～ 1011 GeV. The electroweak energy scale ～ 100 GeV is unnaturally small. No additional global symmetry, like the R-parity, is imposed. The Yukawa couplings and R-parity violating couplings all take their natural values, which are (&)(100 ～ 10-2). Under the family symmetry, only the third generation charged fermions get their masses. This family symmetry is broken in the soft SUSY breaking terms, which result in a hierarchical pattern of the fermion masses. It turns out that for the charged leptons, the τ mass is fromthe Higgs vacuum expectation value (VEV)and the sneutrino VEVs, the muon mass is due to the sneutrino VEVs, and the electron gains its mass due to both Z3L and SUSY breaking. The large neutrino mixing are produced with neutralinos playing the partial role of right-handed neutrinos. |Ve3|, which is for ve-vτ mixing, is expected to be about 0.1. For the quarks, the third generation masses are from the Higgs VEVs, the second generation masses are from quantum corrections, and the down quark mass due to the sneutrino VEVs. It explains mc/ms, ms/me, md ＞ mu, and so on. Other aspects of the model are discussed.
Heavy fermion superconductivity
Brison, Jean-Pascal; Glémot, Loı̈c; Suderow, Hermann; Huxley, Andrew; Kambe, Shinsaku; Flouquet, Jacques
2000-05-01
The quest for a precise identification of the symmetry of the order parameter in heavy fermion systems has really started with the discovery of the complex superconducting phase diagram in UPt 3. About 10 years latter, despite numerous experiments and theoretical efforts, this is still not achieved, and we will quickly review the present status of knowledge and the main open question. Actually, the more forsaken issue of the nature of the pairing mechanism has been recently tackled by different groups with macroscopic or microscopic measurement, and significant progress have been obtained. We will discuss the results emerging from these recent studies which all support non-phonon-mediated mechanisms.
Spinning Particles in Quantum Mechanics and Quantum Field Theory
Corradini, Olindo
2015-01-01
The first part of the lectures, given by O. Corradini, covers introductory material on quantum-mechanical Feynman path integrals, which are here derived and applied to several particle models. We start considering the nonrelativistic bosonic particle, for which we compute the exact path integrals for the case of the free particle and for the harmonic oscillator, and then describe perturbation theory for an arbitrary potential. We then move to relativistic particles, both bosonic and fermionic (spinning) particles. We first investigate them from the classical view-point, studying the symmetries of their actions, then consider their canonical quantization and path integrals, and underline the role these models have in the study of space-time quantum field theories (QFT), by introducing the "worldline" path integral representation of propagators and effective actions. We also describe a special class of spinning particles that constitute a first-quantized approach to higher-spin fields. Since the fifties the qua...
Phenomenology of high colour fermions
Energy Technology Data Exchange (ETDEWEB)
Lust, D.; Streng, K.H.; Papantonopoulos, E.; Zoupanos, G.
1986-04-28
We present the phenomenological consequences of a dynamical scenario for electroweak symmetry breaking and generation of fermion masses, involving the presence of fermions which transform under high colour representations. Particular emphasis is given to the predictions for rare processes and to the possible signals in present and future machines. (orig.).
Radiative seesaw-type mechanism of fermion masses and non-trivial quark mixing
Energy Technology Data Exchange (ETDEWEB)
Arbelaez, Carolina; Hernandez, A.E.C.; Kovalenko, Sergey; Schmidt, Ivan [Universidad Tecnica Federico Santa Maria, Centro Cientifico-Tecnologico de Valparaiso-CCTVal, Valparaiso (Chile)
2017-06-15
We propose a predictive inert two-Higgs doublet model, where the standard model (SM) symmetry is extended by S{sub 3} x Z{sub 2} x Z{sub 12} and the field content is enlarged by extra scalar fields, charged exotic fermions and two heavy right-handed Majorana neutrinos. The charged exotic fermions generate a non-trivial quark mixing and provide one-loop-level masses for the first- and second-generation charged fermions. The masses of the light active neutrinos are generated from a one-loop-level radiative seesaw mechanism. Our model successfully explains the observed SM fermion mass and mixing pattern. (orig.)
Buividovich, P V
2016-01-01
We present first results of classical-statistical real-time simulations of anomalous transport phenomena with overlap fermions. We find that even on small lattices overlap fermions reproduce the real-time anomaly equation with much better precision than Wilson-Dirac fermions on an order of magnitude larger lattices. The difference becomes much more pronounced for quickly changing electromagnetic fields, especially if one takes into account the back-reaction of fermions on electromagnetism. As test cases, we consider chirality pumping in parallel electric and magnetic fields and mixing between the plasmon and the Chiral Magnetic Wave.
Radiative seesaw-type mechanism of fermion masses and non-trivial quark mixing
Arbeláez, Carolina; Hernández, A. E. Cárcamo; Kovalenko, Sergey; Schmidt, Ivan
2017-06-01
We propose a predictive inert two-Higgs doublet model, where the standard model (SM) symmetry is extended by S3⊗ Z2⊗ Z_{12} and the field content is enlarged by extra scalar fields, charged exotic fermions and two heavy right-handed Majorana neutrinos. The charged exotic fermions generate a non-trivial quark mixing and provide one-loop-level masses for the first- and second-generation charged fermions. The masses of the light active neutrinos are generated from a one-loop-level radiative seesaw mechanism. Our model successfully explains the observed SM fermion mass and mixing pattern.
Simulations and Theory of Ion Injection at Non-relativistic Collisionless Shocks
Caprioli, Damiano; Pop, Ana-Roxana; Spitkovsky, Anatoly
2015-01-01
We use kinetic hybrid simulations (kinetic ions-fluid electrons) to characterize the fraction of ions that are accelerated to non-thermal energies at non-relativistic collisionless shocks. We investigate the properties of the shock discontinuity and show that shocks propagating almost along the background magnetic field (quasi-parallel shocks) reform quasi-periodically on ion cyclotron scales. Ions that impinge on the shock when the discontinuity is the steepest are specularly reflected. This is a necessary condition for being injected, but it is not sufficient. Also, by following the trajectories of reflected ions, we calculate the minimum energy needed for injection into diffusive shock acceleration, as a function of the shock inclination. We construct a minimal model that accounts for the ion reflection from quasi-periodic shock barrier, for the fraction of injected ions, and for the ion spectrum throughout the transition from thermal to non-thermal energies. This model captures the physics relevant for ion injection at non-relativistic astrophysical shocks with arbitrary strengths and magnetic inclinations, and represents a crucial ingredient for understanding the diffusive shock acceleration of cosmic rays.
Path Integral for Lattice Staggered Fermions in the Loop Representation
Aroca, J M; Gambini, R
1998-01-01
The path integral formulation in terms of loop variables is introduced for lattice gauge theories with dynamical fermions. The path integral of lattice compact QED with staggered fermions is expressed as a sum over surfaces with border on self-avoiding fermionic paths. Each surface is weighted with a classical action -- written in terms of integer gauge invariant variables -- which gives via transfer matrix method the Hamiltonian of the loop or P-representation. The surfaces correspond to the world sheets of loop-like pure electric flux excitations and meson-like configurations (open electric flux tubes carrying matter fields at their ends). The gauge non-redundancy and the geometric transparency are two appealing features of this description. From the computational point of view, it involves fewer degrees of freedom than the Kogut-Susskind formulation and offers the possibility of alternative numerical methods for dynamical fermions.
SU(8) unification with boson-fermion balance
Adler, Stephen L
2014-01-01
We formulate an $SU(8)$ unification model motivated by requiring that the theory should incorporate the graviton, gravitinos, and the fermions and gauge fields of the standard model, with boson--fermion balance. Gauge field $SU(8)$ anomalies cancel between the gravitinos and spin $\\frac {1}{2}$ fermions. The 56 of scalars breaks $SU(8)$ to $SU(3)_{family} \\times SU(5)/Z_5$, with the fermion representation content needed for ``flipped'' $SU(5)$, and with the residual scalars in the representations needed for further gauge symmetry breaking to the standard model. Yukawa couplings of the 56 scalars to the fermions are forbidden by chiral and gauge symmetries. In the limit of vanishing gauge coupling, there are $N=1$ and $N=8$ supersymmetries relating the scalars to the fermions, which restrict the form of scalar self-couplings and should improve the convergence of perturbation theory, if not making the theory finite and ``calculable''. In an Appendix we give an analysis of symmetry breaking by a Higgs component,...
Dwarf spheroidal galaxies as degenerate gas of free fermions
Domcke, Valerie
2014-01-01
In this paper we analyze a simple scenario in which Dark Matter (DM) consists of free fermions with mass $m_f$. We assume that on galactic scales these fermions are capable to form a degenerate Fermi gas, in which stability against gravitational collapse is ensured by the Pauli exclusion principle. The mass density of the resulting configuration is governed by a non-relativistic Lane-Emden equation, thus leading to a universal cored profile that depends only on one free parameter in addition to $m_f$. After reviewing the basic formalism, we test this scenario against experimental data describing the dispersion velocity of the eight classical dwarf spheroidal galaxies of the Milky Way. We find that, despite its extreme simplicity, the model exhibits a good fit of the data and realistic predictions for the size of DM halos providing that $m_f \\simeq 200$ eV. We propose a concrete realization of this model in which DM is produced non-thermally via inflaton decay. We show that imposing the correct relic abundance...
Dwarf spheroidal galaxies as degenerate gas of free fermions
Energy Technology Data Exchange (ETDEWEB)
Domcke, Valerie; Urbano, Alfredo, E-mail: valerie.domcke@sissa.it, E-mail: alfredo.urbano@sissa.it [SISSA - International School for Advanced Studies, via Bonomea 256, Trieste, 34136 Italy (Italy)
2015-01-01
In this paper we analyze a simple scenario in which Dark Matter (DM) consists of free fermions with mass m{sub f}. We assume that on galactic scales these fermions are capable of forming a degenerate Fermi gas, in which stability against gravitational collapse is ensured by the Pauli exclusion principle. The mass density of the resulting con figuration is governed by a non-relativistic Lane-Emden equation, thus leading to a universal cored profile that depends only on one free parameter in addition to m{sub f}. After reviewing the basic formalism, we test this scenario against experimental data describing the velocity dispersion of the eight classical dwarf spheroidal galaxies of the Milky Way. We find that, despite its extreme simplicity, the model exhibits a good fit to the data and realistic predictions for the size of DM halos providing that m{sub f}≅ 200 eV. Furthermore, we show that in this setup larger galaxies correspond to the non-degenerate limit of the gas. We propose a concrete realization of this model in which DM is produced non-thermally via inflaton decay. We show that imposing the correct relic abundance and the bound on the free-streaming length constrains the inflation model in terms of inflaton mass, its branching ratio into DM and the reheating temperature.
Dielectric laser acceleration of non-relativistic electrons at a photonic structure
Energy Technology Data Exchange (ETDEWEB)
Breuer, John
2013-08-29
This thesis reports on the observation of dielectric laser acceleration of non-relativistic electrons via the inverse Smith-Purcell effect in the optical regime. Evanescent modes in the vicinity of a periodic grating structure can travel at the same velocity as the electrons along the grating surface. A longitudinal electric field component is used to continuously impart momentum onto the electrons. This is only possible in the near-field of a suitable photonic structure, which means that the electron beam has to pass the structure within about one wavelength. In our experiment we exploit the third spatial harmonic of a single fused silica grating excited by laser pulses derived from a Titanium:sapphire oscillator and accelerate non-relativistic 28 keV electrons. We measure a maximum energy gain of 280 eV, corresponding to an acceleration gradient of 25 MeV/m, already comparable with state-of-the-art radio-frequency linear accelerators. To experience this acceleration gradient the electrons approach the grating closer than 100 nm. We present the theory behind grating-based particle acceleration and discuss simulation results of dielectric laser acceleration in the near-field of photonic grating structures, which is excited by near-infrared laser light. Our measurements show excellent agreement with our simulation results and therefore confirm the direct acceleration with the light field. We further discuss the acceleration inside double grating structures, dephasing effects of non-relativistic electrons as well as the space charge effect, which can limit the attainable peak currents of these novel accelerator structures. The photonic structures described in this work can be readily concatenated and therefore represent a scalable realization of dielectric laser acceleration. Furthermore, our structures are directly compatible with the microstructures used for the acceleration of relativistic electrons demonstrated in parallel to this work by our collaborators in
Construction of the ground state in nonrelativistic QED by continuous flows
Bach, Volker; Könenberg, Martin
For a nonrelativistic hydrogen atom minimally coupled to the quantized radiation field we construct the ground state projection P by a continuous approximation scheme as an alternative to the iteration scheme recently used by Fröhlich, Pizzo, and the first author [V. Bach, J. Fröhlich, A. Pizzo, Infrared-finite algorithms in QED: The groundstate of an atom interacting with the quantized radiation field, Comm. Math. Phys. (2006), doi: 10.1007/s00220-005-1478-3]. That is, we construct P=limP as the limit of a continuously differentiable family ()t⩾0 of ground state projections of infrared regularized Hamiltonians H. Using the ODE solved by this family of projections, we show that the norm ‖P‖ of their derivative is integrable in t which in turn yields the convergence of P by the fundamental theorem of calculus.
Thermometry for Dirac fermions in graphene
Energy Technology Data Exchange (ETDEWEB)
Liu, Fan-Hung; Hsu, Chang-Shun; Lo, Shun-Tsung [National Taiwan University, Taipei, Taiwan (China); and others
2015-01-15
We use both the zero-magnetic-field resistivity and the phase coherence time determined by weak localization as independent thermometers for Dirac fermions (DF) in multilayer graphene. In the high current (I) region, there exists a simple power law T{sub DF} ∼ I{sup ∼0.5}, where T{sub DF} is the effective Dirac fermion temperature for epitaxial graphene on SiC. In contrast, T{sub DF} ∼ I{sup ∼1} in exfoliated multilayer graphene. We discuss possible reasons for the different power laws observed in these multilayer graphene systems. Our experimental results on DF-phonon scattering may find applications in graphene-based nanoelectronics.
Horava-Lifshitz theory as a Fermionic Aether in Ashtekar gravity
Alexander, Stephon; Marciano, Antonino
2012-01-01
We show how Ho\\v{r}ava-Lifshitz (HL) theory appears naturally in the Ashtekar formulation of relativity if one postulates the existence of a fermionic field playing the role of aether. The spatial currents associated with this field must be switched off for the equivalence to work. Therefore the field supplies the preferred frame associated with breaking refoliation (time diffeomorphism) invariance, but obviously the symmetry is only spontaneously broken if the field is dynamic. When Dirac fermions couple to the gravitational field via the Ashtekar variables, the low energy limit of HL gravity, recast in the language of Ashtekar variables, naturally emerges (provided the spatial fermion current identically vanishes). HL gravity can therefore be interpreted as a time-like current, or a Fermi aether, that fills space-time, with the Immirzi parameter, a chiral fermionic coupling, and the fermionic charge density fixing the value of the parameter $\\lambda$ determining HL theory. This reinterpretation sheds light ...
Redkov, V M
1999-01-01
The paper concerns a problem of the Dirac fermion doublet in the external monopole potential obtained by embedding the Abelian monopole solution in the non-Abelian scheme. In this case, the doublet-monopole Hamiltonian is invariant under operations consisting of a complex and one parametric Abelian subgroup in S0(3.C). This symmetry results in a certain freedom in choosing a discrete operator N(A) (A is a complex number) entering the complete set of quantum variables. The same complex number A represents an additional parameter at the basis functions. The generalized inversion like operator N(A) affords certain generalized N(A)-parity selection rules. All the different sets of basis functions Psi(A) determine the same Hilbert space. The functions Psi(A) decompose into linear combinations of Psi(A=0): Psi(A) = F(A) Psi(A=0). However, the bases considered turn out to be nonorthogonal ones when A is a complex number; the latter correlates with the non-self-conjugacy of the N(A) at complex A-s. The meaning of pos...
Δ - Δ resonance in the nonrelativistic quark model
Cvetič, M.; Golli, B.; Mankoč-Borštnik, N.; Rosina, M.
1980-06-01
The Δ - Δ resonance is treated in the nonrelativistic quark model. The trial wave function is a colour singlet including N-N, Δ - Δ and coloured baryon channels. The effective Δ - Δ potential is repulsive at all distances for T=0, S=1, L=0,2,4 while for T=3, S=0, L=0 and T=0, S=3, L=0 it has a minimum. The GCM calculation gives for the latter state the binding emergy ∼ -40 MeV.
Conservation of energy and momentum in nonrelativistic plasmas
Energy Technology Data Exchange (ETDEWEB)
Sugama, H.; Watanabe, T.-H. [National Institute for Fusion Science, Toki 509-5292 (Japan); Graduate University for Advanced Studies, Toki 509-5292 (Japan); Nunami, M. [National Institute for Fusion Science, Toki 509-5292 (Japan)
2013-02-15
Conservation laws of energy and momentum for nonrelativistic plasmas are derived from applying Noether's theorem to the action integral for the Vlasov-Poisson-Ampere system [Sugama, Phys. Plasmas 7, 466 (2000)]. The symmetric pressure tensor is obtained from modifying the asymmetric canonical pressure tensor with using the rotational symmetry of the action integral. Differences between the resultant conservation laws and those for the Vlasov-Maxwell system including the Maxwell displacement current are clarified. These results provide a useful basis for gyrokinetic conservation laws because gyrokinetic equations are derived as an approximation of the Vlasov-Poisson-Ampere system.
Scattering theory the quantum theory of nonrelativistic collisions
Taylor, John R
2006-01-01
This graduate-level text is intended for any student of physics who requires a thorough grounding in the quantum theory of nonrelativistic scattering. It is designed for readers who are already familiar with the general principles of quantum mechanics and who have some small acquaintance with scattering theory. Study of this text will allow students of atomic or nuclear physics to begin reading the literature and tackling real problems, with a complete grasp of the underlying principles. For students of high-energy physics, it provides the necessary background for later study of relativistic p
Fermions tunneling from the Horowitz-Strominger Dilaton black hole
Institute of Scientific and Technical Information of China (English)
LI Oiang; ZENG XiaoXiong
2009-01-01
Based on the work of Kerner and Mann, fermions tunneling from the Horowitz-Strominger Dilaton black hole on the membrane is studied. Owing to the coupling among electromagnetic field, matter field and gravity field, the Dirac equation of charged particles is introduced, and according to that, the expected emission temperature is obtained. After the self-gravitational interaction is considered, it is found that the tunneling rate of fermions also satisfies the underlying Unitary theory as the case of scalar parti-cles.
On the question of symmetries in non-relativistic diffeomorphism invariant theories
Banerjee, Rabin; Mukherjee, Pradip
2016-01-01
Nonrelativistic diffeomorphism invariance has recently emerged as a powerful tool for investigating various phenomena. The flat limit of such an invariance which should yield the Galilean invariance is, surprisingly, riddled with ambiguities and anomalies. We show that our approach, based on Galilean gauge theory, resolves these shortcomings. As a spin-off, we provide a systematic and unique way of interpreting nonrelativistic diffeomorphism invariance and Galilean invariance as appropriate nonrelativistic limits of relativistic invariances in curved and flat backgrounds, respectively. The complementary role of flat and nonrelativistic limits is highlighted.
Majorana fermions in hybrid superconductor-semiconductor nanowire devices
Mourik, V.; Zuo, K.; van Woerkom, D. J.; de Vries, F. R.; Gul, O.; Zhang, H.; de Moor, M. A. W.; Car, D.; Bakkers, E. P. A. M.; Kouwenhoven, L. P.
2015-03-01
Our experiment carried out in hybrid superconductor-semiconductor nanowire devices gave the first experimental indications for the existence of Majorana fermions, but many open questions need to be answered. Majorana fermions have to come in pairs, before we were only capable of probing one Majorana fermion. Majorana fermions should be fully gate controllable, which could not be demonstrated convincingly. Upon bringing Majorana fermions closer together, an energy splitting between the two is expected, giving rise to a pair of split peaks instead of a single zero bias peak (ZBP). We are performing new experiments in similar but improved three terminal normal-superconductor-normal InSb nanowire devices. This enables the possibility to probe Majorana fermions occurring at the ends of the superconducting contact by using tunneling spectroscopy. Furthermore, the devices have an improved gate design enabling more efficient gating under the superconducting contact and they have improved contact interfaces resulting in less undesired resonant states. We have observed ZBP's in a large magnetic field range, an oscillatory behavior from ZBP to split peak and back, and tunability of ZBP's by gates underneath the superconducting contact.
Supersymmetric Dynamics of a Spin-1/2 Particle in an Extended External Field
Dias, Gilmar de Souza
2011-01-01
We consider a electron in a external field in D=5, through the Dirac equation in the Galilean symmetry approach, and in the Lorentz symmetry approach; from these we perform the nonrelativistic limit, then we procede the supersymmetry of the same that is associated with the Galilean symmetry, we identify as a supersymmetry sector from the quantum-mechanical dynamics, and we got the algebra of fermionic charges. We naturally define as extra electrical vector E, and interpret the terms of energy coming from the fifth dimension. The energy from the fifth dimension, criate this extra electrical vector E, associated with the fifth component of the external electrical field A, this makes the energy flow from the fifth dimension to the usual three-dimensional space, when some symmetries of the usual space are broken, giving a preferential direction in the space, even though the standard electrical and magnetic fields are null.
Nonperturbative emergence of the Dirac fermion in a strongly correlated composite Fermi liquid
Yang, Yibin; Luo, Xi; Yu, Yue
2017-01-01
The classic composite fermion field theory [B. I. Halperin, P. A. Lee, and N. Read, Phys. Rev. B 47, 7312 (1993)], 10.1103/PhysRevB.47.7312 builds up an excellent framework to uniformly study important physical objects and globally explain anomalous experimental phenomena in fractional quantum Hall physics while there are also inherent weaknesses. We present a nonperturbative emergent Dirac fermion theory from this strongly correlated composite fermion field theory, which overcomes these serious long-standing shortcomings. The particle-hole symmetry of the Dirac equation resolves this particle-hole symmetry enigma in the composite fermion field theory. With the help of presented numerical data, we show that for main Jain's sequences of fractional quantum Hall effects, this emergent Dirac fermion theory in mean field approximation is most likely stable.
Itoh, K; Sawanaka, H; So, H; Ukita, N
2003-01-01
We present a lattice theory with an exact fermionic symmetry, which mixes the link and the fermionic variables. The staggered fermionic variables may be reconstructed into a Majorana fermion in the continuum limit. The gauge action has a novel structure. Though it is the ordinary plaquette action, two different couplings are assigned in the ``Ichimatsu pattern'' or the checkered pattern. In the naive continuum limit, the fermionic symmetry survives as a continuum (or an $O(a^0)$) symmetry. The transformation of the fermion is proportional to the field strength multiplied by the difference of the two gauge couplings in this limit. This work is an extension of our recently proposed cell model toward the realization of supersymmetric Yang-Mills theory on lattice.
A novel and economical explanation for SM fermion masses and mixings
Energy Technology Data Exchange (ETDEWEB)
Hernandez, A.E.C. [Universidad Tecnica Federico Santa Maria and Centro Cientifico-Tecnologico de Valparaiso, Valparaiso (Chile)
2016-09-15
I propose the first multiscalar singlet extension of the standard model (SM), which generates tree level top quark and exotic fermion masses as well as one and three loop level masses for charged fermions lighter than the top quark and for light active neutrinos, respectively, without invoking electrically charged scalar fields. That model, which is based on the S{sub 3} x Z{sub 8} discrete symmetry, successfully explains the observed SM fermion mass and mixing pattern. The charged exotic fermions induce one loop level masses for charged fermions lighter than the top quark. The Z{sub 8} charged scalar singlet χ generates the observed charged fermion mass and quark mixing pattern. (orig.)
A local factorization of the fermion determinant in lattice QCD
Cè, Marco; Schaefer, Stefan
2016-01-01
We introduce a factorization of the fermion determinant in lattice QCD with Wilson-type fermions that leads to a bosonic action 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 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.
Holographic Fermions in Anisotropic Einstein-Maxwell-Dilaton-Axion Theory
Directory of Open Access Journals (Sweden)
Li-Qing Fang
2015-01-01
Full Text Available We investigate the properties of the holographic Fermionic system dual to an anisotropic charged black brane bulk in Einstein-Maxwell-Dilaton-Axion gravity theory. We consider the minimal coupling between the Dirac field and the gauge field in the bulk gravity theory and mainly explore the dispersion relation exponents of the Green functions of the dual Fermionic operators in the dual field theory. We find that along both the anisotropic and the isotropic directions the Fermi momentum will be effected by the anisotropy of the bulk theory. However, the anisotropy has influence on the dispersion relation which is almost linear for massless Fermions with charge q=2. The universal properties that the mass and the charge of the Fermi possibly correspond to nonlinear dispersion relation are also investigated.
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.
Fermions on the Worldsheet of Effective Strings via Coset Construction
Mohsen, Ali
2016-01-01
In this paper the detailed CCWZ procedure for introducing fermions on the world sheet of a string propagating in flat space-time is presented. The theory of nonlinear realizations is used to derive the transformation as well as the interactions of fermionic matter fields under arbitrary spinorial representations of the unbroken subgroup. This demonstrates that even for non-supersymmetric spinors, the interactions are still severely restricted by the nonlinearly realized symmetry. We also explain how supersymmetric models provide an example for this construction with Goldstinos as matter fields, and how one can use the $\\kappa$-symmetry of the Green Schwarz action in particular, to verify this nonlinear transformation for a specific matter field representation. We finally restrict the target space dimension without reference to supersymmetry, but rather by imposing one-loop integrability on a fermionic string that nonlinearly realizes Poincare symmetry. This singles out the critical dimension $D=10$ for hetero...
Higher loop renormalization of fermion bilinear operators
Skouroupathis, A
2007-01-01
We compute the two-loop renormalization functions, in the RI' scheme, of local bilinear quark operators $\\bar\\psi\\Gamma\\psi$, where $\\Gamma$ denotes the Scalar and Pseudoscalar Dirac matrices, in the lattice formulation of QCD. We consider both the flavor non-singlet and singlet operators; the latter, in the scalar case, leads directly to the two-loop fermion mass renormalization, $Z_m$. As a prerequisite for the above, we also compute the quark field renormalization, $Z_\\psi$, up to two loops. We use the clover action for fermions and the Wilson action for gluons. Our results are given as a polynomial in $c_{SW}$, in terms of both the renormalized and bare coupling constant, in the renormalized Feynman gauge. We also confirm the 1-loop renormalization functions, for generic gauge. A longer write-up of the present work, including the conversion of our results to the MSbar scheme and a generalization to arbitrary fermion representations, can be found in arXiv:0707.2906 .
Entanglement in fermionic Fock space
Sárosi, Gábor
2013-01-01
We propose a generalization of the usual SLOCC and LU classification of entangled pure state fermionic systems based on the Spin group. Our generalization uses the fact that there is a representation of this group acting on the fermionic Fock space which when restricted to fixed particle number subspaces recovers naturally the usual SLOCC transformations. The new ingredient is the occurrence of Bogoliubov transformations of the whole Fock space changing the particle number. The classification scheme built on the Spin group prohibits naturally entanglement between states containing even and odd number of fermions. In our scheme the problem of classification of entanglement types boils down to the classification of spinors where totally separable states are represented by so called pure spinors. We construct the basic invariants of the Spin group and show how some of the known SLOCC invariants are just their special cases. As an example we present the classification of fermionic systems with a Fock space based ...
Investigation of Properties of Exotic Nuclei in Non-relativistic and Relativistic Models
Institute of Scientific and Technical Information of China (English)
2001-01-01
Properties of exotic nuclei are described by non-relativistic and relativistic models. The relativistic mean field theory predicts one proton halo in 26,27,28P and two proton halos in 27,28,29S, recently, one proton halo in 26,27,28P has been found experimentally in MSU lab. The relativistic Hartree-Fock theory has been used to investigate the contribution of Fock term and isovector mesons to the properties of exotic nuclei. It turns out that the influence of the Fock term and isovector mesons on the properties of neutron extremely rich nuclei is very different from that of near stable nuclei. Meanwhile, the deformed Hartree-Fock-Bogoliubov theory has been employed to describe the ground state properties of the isotopes for some light nuclei.
Nonrelativistic limit of the abelianized ABJM model and the ADS/CMT correspondence
Lopez-Arcos, Cristhiam; Nastase, Horatiu
2015-01-01
We consider the nonrelativistic limit of the abelian reduction of the massive ABJM model proposed in \\cite{Mohammed:2012gi}, obtaining a supersymmetric version of the Jackiw-Pi model. The system exhibits an ${\\cal N}=2$ Super-Schr\\"odinger symmetry with the Jackiw-Pi vortices emerging as BPS solutions. We find that this $(2+1)$-dimensional abelian field theory is dual to a certain (3+1)-dimensional gravity theory that differs somewhat from previously considered abelian condensed matter stand-ins for the ABJM model. We close by commenting on progress in the top-down realization of the AdS/CMT correspondence in a critical string theory.
Kershaw-type transport equations for fermionic radiation
Banach, Zbigniew; Larecki, Wieslaw
2017-08-01
Besides the maximum entropy closure procedure, other procedures can be used to close the systems of spectral moment equations. In the case of classical and bosonic radiation, the closed-form analytic Kershaw-type and B-distribution closure procedures have been used. It is shown that the Kershaw-type closure procedure can also be applied to the spectral moment equations of fermionic radiation. First, a description of the Kershaw-type closure for the system consisting of an arbitrary number of one-dimensional moment equations is presented. Next, the Kershaw-type two-field and three-field transport equations for fermionic radiation are analyzed. In the first case, the independent variables are the energy density and the heat flux. The second case includes additionally the flux of the heat flux as an independent variable. The generalization of the former two-field case to three space dimensions is also presented. The fermionic Kershaw-type closures differ from those previously derived for classical and bosonic radiation. It is proved that the obtained one-dimensional systems of transport equations are strictly hyperbolic and causal. The fermionic Kershaw-type closure functions behave qualitatively in the same way as the fermionic maximum entropy closure functions, but attain different numerical values.
Spin and localization of relativistic fermions and uncertainty relations
Céleri, Lucas C.; Kiosses, Vasilis; Terno, Daniel R.
2016-12-01
We discuss relations between several relativistic spin observables and derive a Lorentz-invariant characteristic of a reduced spin density matrix. A relativistic position operator that satisfies all the properties of its nonrelativistic analog does not exist. Instead we propose two causality-preserving positive operator-valued measures (POVMs) that are based on projections onto one-particle and antiparticle spaces, and on the normalized energy density. They predict identical expectation values for position. The variances differ by less than a quarter of the squared de Broglie wavelength and coincide in the nonrelativistic limit. Since the resulting statistical moment operators are not canonical conjugates of momentum, the Heisenberg uncertainty relations need not hold. Indeed, the energy density POVM leads to a lower uncertainty. We reformulate the standard equations of the spin dynamics by explicitly considering the charge-independent acceleration, allowing a consistent treatment of backreaction and inclusion of a weak gravitational field.
Saxena, Pooja
2016-01-01
A search for high mass Higgs boson of the MSSM decaying into two fermions using the first 2015 data at 13 TeV is presented. The four final decay channels of mu \\tau_h, e \\tau_h, \\tau_h \\tau_h and e mu 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.
Neutrinos Are Nearly Dirac Fermions
Cahill, K E
1999-01-01
Neutrino masses and mixings are analyzed in terms of left-handed fields and a 6x6 complex symmetric mass matrix whose singular values are the neutrino masses. An angle theta_nu characterizes the kind of the neutrinos, with theta_nu = 0 for Dirac neutrinos and theta_nu = pi/2 for Majorana neutrinos. If theta_nu = 0, then baryon-minus-lepton number is conserved. When theta_nu is approximately zero, the six neutrino masses coalesce into three nearly degenerate pairs. Thus the smallness of the differences in neutrino masses exhibited in the solar and atmospheric neutrino experiments and the stringent limits on neutrinoless double-beta decay are naturally explained if B-L is approximately conserved and neutrinos are nearly Dirac fermions. If one sets theta_nu = 0.0005, suppresses inter-generational mixing, and imposes a quark-like mass hierarchy, then one may fit the essential features of the solar, reactor, and atmospheric neutrino experiments with otherwise random mass matrices in the eV range. This B-L model le...
Das, Joy Prakash; Setlur, Girish S.
2017-10-01
The one step fermionic ladder refers to two parallel Luttinger Liquids (poles of the ladder) placed such that there is a finite probability of electrons hopping between the two poles at a pair of opposing points along each of the poles. The many-body Green function for such a system is calculated in presence of forward scattering interactions using the powerful non-chiral bosonization technique (NCBT). This technique is based on a non-standard harmonic analysis of the rapidly varying parts of the density fields appropriate for the study of strongly inhomogeneous ladder systems. The closed analytical expression for the correlation function obtained from NCBT is nothing but the series involving the RPA (Random Phase Approximation) diagrams in powers of the forward scattering coupling strength resummed to include only the most singular terms with the source of inhomogeneities treated exactly. Finally the correlation functions are used to study physical phenomena such as Friedel oscillations and the conductance of such systems with the potential difference applied across various ends.
Newton-Cartan (super)gravity as a non-relativistic limit
Bergshoeff, Eric; Rosseel, Jan; Zojer, Thomas
2015-01-01
We define a procedure that, starting from a relativistic theory of supergravity, leads to a consistent, non-relativistic version thereof. As a first application we use this limiting procedure to show how the Newton-Cartan formulation of non-relativistic gravity can be obtained from general relativit
Landau Levels of Majorana Fermions in a Spin Liquid.
Rachel, Stephan; Fritz, Lars; Vojta, Matthias
2016-04-22
Majorana fermions, originally proposed as elementary particles acting as their own antiparticles, can be realized in condensed-matter systems as emergent quasiparticles, a situation often accompanied by topological order. Here we propose a physical system which realizes Landau levels-highly degenerate single-particle states usually resulting from an orbital magnetic field acting on charged particles-for Majorana fermions. This is achieved in a variant of a quantum spin system due to Kitaev which is distorted by triaxial strain. This strained Kitaev model displays a spin-liquid phase with charge-neutral Majorana-fermion excitations whose spectrum corresponds to that of Landau levels, here arising from a tailored pseudomagnetic field. We show that measuring the dynamic spin susceptibility reveals the Landau-level structure by a remarkable mechanism of probe-induced bound-state formation.
Kermions: quantization of fermions on Kerr space-time
Casals, Marc; Nolan, Brien C; Ottewill, Adrian C; Winstanley, Elizabeth
2013-01-01
We study a quantum fermion field on a background non-extremal Kerr black hole. We discuss the definition of the standard black hole quantum states (Boulware, Unruh and Hartle-Hawking), focussing particularly on the differences between fermionic and bosonic quantum field theory. Since all fermion modes (both particle and anti-particle) have positive norm, there is much greater flexibility in how quantum states are defined compared with the bosonic case. In particular, we are able to define a candidate `Boulware'-like state, empty at both past and future null infinity; and a candidate `Hartle-Hawking'-like equilibrium state, representing a thermal bath of fermions surrounding the black hole. Neither of these states have analogues for bosons on a non-extremal Kerr black hole and both have physically attractive regularity properties. We also define a number of other quantum states, numerically compute differences in expectation values of the fermion current and stress-energy tensor between two states, and discuss...
Effective approach to non-relativistic quantum mechanics
Jacobs, David M
2015-01-01
Boundary conditions on non-relativistic wavefunctions are generally not completely constrained by the basic precepts of quantum mechanics, so understanding the set of possible self-adjoint extensions of the Hamiltonian is required. For real physical systems, non-trivial self-adjoint extensions have been used to model contact potentials when those interactions are expected a priori. However, they must be incorporated into the effective description of any quantum mechanical system in order to capture possible short-distance physics that does not decouple in the low energy limit. Here, an approach is described wherein an artificial boundary is inserted at an intermediate scale on which boundary conditions may encode short-distance effects that are hidden behind the boundary. Using this approach, an analysis is performed of the free particle, harmonic oscillator, and Coulomb potential in three dimensions. Requiring measurable quantities, such as spectra and cross sections, to be independent of this artificial bou...
The Thomas-Fermi Quark Model: Non-Relativistic Aspects
Liu, Quan
2012-01-01
Non-relativistic aspects of the Thomas-Fermi statistical quark model are developed. A review is given and our modified approach to spin in the model is explained. Our results are limited so far to two inequivalent simultaneous wave functions which can apply to multiple degenerate flavors. An explicit spin interaction is introduced, which requires the introduction of a generalized spin "flavor". Although the model is designed to be most reliable for many-quark states, we find surprisingly that it may be used to fit the low energy spectrum of octet and decouplet baryons. The low energy fit allows us to investigate the six-quark doubly strange H-dibaryon state, possible 6 quark nucleon-nucleon resonances and flavor symmetric strange states of higher quark content.
Nonrelativistic QED approach to the bound-electron g factor
Pachucki, K; Yerokhin, V A
2004-01-01
Within a systematic approach based on nonrelativistic quantum electrodynamics (NRQED), we derive the one-loop self-energy correction of order alpha (Zalpha)^4 to the bound-electron g factor. In combination with numerical data, this analytic result improves theoretical predictions for the self-energy correction for carbon and oxygen by an order of magnitude. Basing on one-loop calculations, we obtain the logarithmic two-loop contribution of order alpha^2 (Zalpha)^4 ln[(Zalpha)^-2] and the dominant part of the corresponding constant term. The results obtained improve the accuracy of the theoretical predictions for the 1S bound-electron g factor and influence the value of the electron mass determined from g factor measurements.
Nonrelativistic QED Approach to the Bound-Electron g Factor
Pachucki, Krzysztof; Jentschura, Ulrich D.; Yerokhin, Vladimir A.
2004-10-01
Within a systematic approach based on nonrelativistic quantum electrodynamics, we derive the one-loop self-energy correction of order α(Zα)4 to the bound-electron g factor. In combination with numerical data, this analytic result improves theoretical predictions for the self-energy correction for carbon and oxygen by an order of magnitude. Basing on one-loop calculations, we obtain the logarithmic two-loop contribution of order α2(Zα)4ln([(Zα)-2] and the dominant part of the corresponding constant term. The results obtained improve the accuracy of the theoretical predictions for the 1S bound-electron g factor and influence the value of the electron mass determined from g-factor measurements.
Studying fermionic ghost imaging with independent photons
Liu, Jianbin; Zhou, Yu; Zheng, Huaibin; Chen, Hui; Li, Fu-li; Xu, Zhuo
2016-12-01
Ghost imaging with thermal fermions is calculated based on two-particle interference in Feynman's path integral theory. It is found that ghost imaging with thermal fermions can be simulated by ghost imaging with thermal bosons and classical particles. Photons in pseudothermal light are employed to experimentally study fermionic ghost imaging. Ghost imaging with thermal bosons and fermions is discussed based on the point-to-point (spot) correlation between the object and image planes. The employed method offers an efficient guidance for future ghost imaging with real thermal fermions, which may also be generalized to study other second-order interference phenomena with fermions.
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.
Magnetism and superconductivity in heavy fermion systems
Energy Technology Data Exchange (ETDEWEB)
Flouquet, J. (DRFMC, C.E.N.G., 38 - Grenoble (France)); Brison, J.P.; Hasselbach, K.; Taillefer, L. (C.N.R.S., 38 - Grenoble (France)); Behnia, K.; Jaccard, D. (DPMC, Geneva Univ. (Switzerland)); Visser, A. de (Natuurkundig Lab., Univ. van Amsterdam (Netherlands))
1991-12-01
The normal and superconducting properties of heavy fermion compounds are reviewed. The discussion is focus on the three uranium compounds: UBe{sub 13}, UPt{sub 3} and URu{sub 2}Si{sub 2}. Special attention is given: 1) to unusual (H.T) superconducting phase diagram as discovered in UPt{sub 3} where two successive superconducting phases seem to occur in zero magnetic field; 2) to the role of long range ordering as found in URu{sub 2}Si{sub 2} and UPt{sub 3}. (orig.).
Hierarchy spectrum of SM fermions: from top quark to electron neutrino
Xue, She-Sheng
2016-11-01
In the SM gauge symmetries and fermion content of neutrinos, charged leptons and quarks, we study the effective four-fermion operators of Einstein-Cartan type and their contributions to the Schwinger-Dyson equations of fermion self-energy functions. The study is motivated by the speculation that these four-fermion operators are probably originated due to the quantum gravity, which provides the natural regularization for chiral-symmetric gauge field theories. In the chiral-gauge symmetry breaking phase, as to achieve the energetically favorable ground state, only the top-quark mass is generated via the spontaneous symmetry breaking, and other fermion masses are generated via the explicit symmetry breaking induced by the top-quark mass, four-fermion interactions and fermion-flavor mixing matrices. A phase transition from the symmetry breaking phase to the chiral-gauge symmetric phase at TeV scale occurs and the drastically fine-tuning problem can be resolved. In the infrared fixed-point domain of the four-fermion coupling for the SM at low energies, we qualitatively obtain the hierarchy patterns of the SM fermion Dirac masses, Yukawa couplings and family-flavor mixing matrices with three additional right-handed neutrinos ν R f . Large Majorana masses and lepton-number symmetry breaking are originated by the four-fermion interactions among ν R f and their left-handed conjugated fields ν R fc . Light masses of gauged Majorana neutrinos in the normal hierarchy (10-5 - 10-2 eV) are obtained consistently with neutrino oscillations. We present some discussions on the composite Higgs phenomenology and forward-backward asymmetry of toverline{t} -production, as well as remarks on the candidates of light and heavy dark matter particles (fermions, scalar and pseudoscalar bosons).
Ribas, M. O.; Samojeden, L. L.; Devecchi, F. P.; Kremer, G. M.
2015-10-01
In this work we investigate a model for the early Universe in a Bianchi type-I metric, where the sources of the gravitational field are a fermionic and a bosonic field, interacting through a Yukawa potential, following the standard model of elementary particles. It is shown that the fermionic field has a negative pressure, while the boson has a small positive pressure. The fermionic field is the responsible for an accelerated regime at early times, but since the total pressure tends to zero for large times, a transition to a decelerated regime occurs. Here the Yukawa potential answers for the duration of the accelerated regime, since by decreasing the value of its coupling constant the transition accelerated-decelerated occurs in later times. The isotropization which occurs for late times is due to the presence of the fermionic field as one of the sources of the gravitational field.
Ribas, M O; Devecchi, F P; Kremer, G M
2015-01-01
In this work we investigate a model for the early Universe in a Bianchi type-I metric, where the sources of the gravitational field are a fermionic and a bosonic field, interacting through a Yukawa potential, following the standard model of elementary particles. It is shown that the fermionic field has a negative pressure, while the boson has a small positive pressure. The fermionic field is the responsible for an accelerated regime at early times, but since the total pressure tends to zero for large times, a transition to a decelerated regime occurs. Here the Yukawa potential answers for the duration of the accelerated regime, since by decreasing the value of its coupling constant the transition accelerated-decelerated occurs in later times. The isotropization which occurs for late times is due to the presence of the fermionic field as one of the sources of the gravitational field.
Borstnik, Norma Susana Mankoc
2012-01-01
The spin-charge-family theory offers a possible explanation for the assumptions of the standard model, interpreting the standard model as its low energy effective manifestation. The standard model Higgs and Yukawa couplings are explained as an effective replacement for several scalar fields, all of bosonic (adjoint) representations with respect to all the charge groups, with the family groups included. Assuming the Lagrange function for all scalar fields to be of the renormalizable kind, properties of the scalar fields on the tree level are discussed. Free scalar fields (mass eigenstates) differ from either those, which couple to $Z_m$, or to $W^{\\pm}_{m}$ or to each family member of each of the four families, which further differ among themselves. Consequently the spin-charge-family theory predictions differ from those of the standard model.
Fermionic influence (action) on inflationary fluctuations
Boyanovsky, Daniel
2016-01-01
Motivated by apparent persistent large scale anomalies in the CMB we study the influence of fermionic degrees of freedom on the dynamics of inflaton fluctuations as a possible source of violations of (nearly) scale invariance on cosmological scales. We obtain the non-equilibrium effective action of an inflaton-like scalar field with Yukawa interactions ($Y_{D,M}$) to light \\emph{fermionic} degrees of freedom both for Dirac and Majorana fields in de Sitter space-time. The effective action leads to Langevin equations of motion for the fluctuations of the inflaton-like field, with self-energy corrections and a stochastic gaussian noise. We solve the Langevin equation in the super-Hubble limit implementing a dynamical renormalization group resummation. For a nearly massless inflaton its power spectrum of super Hubble fluctuations is \\emph{enhanced}, $\\mathcal{P}(k;\\eta) = (\\frac{H}{2\\pi})^2\\,e^{\\gamma_t[-k\\eta] }$ with $\\gamma_t[-k\\eta] = \\frac{1}{6\\pi^2} \\Big[\\sum_{i=1}^{N_D}{Y^2_{i,D}}+2\\sum_{j=1}^{N_M}{Y^2_{j,...
The effective electromagnetic interaction in a dense fermionic medium in QED$_{2+1}$
Skalozub, V V
1995-01-01
Basing upon properties of polarization operator and three-fotonic vertex the effective Lagrangian of the electromagnetic field in a dense fermionic medium in QED_{2+1} is constructed. As an application the modification of magnetic field generation by static electric charge is considered. It is shown a possibility of attraction between planar equally charged fermions in a presence of external magnetic field for certain range of values of H and chemical potential.
Manifestly Gauge Covariant Formulation of Lattice Chiral Fermions
Okuyama, K; Okuyama, Kiyoshi; Suzuki, Hiroshi
1997-01-01
We propose a new formulation of chiral fermions on a lattice, on the basis of a lattice extension of the covariant regularization scheme in continuum field theory. The species doublers do not emerge. The real part of the effective action is just one half of that of Dirac-Wilson fermion and is always gauge invariant even with a finite lattice spacing. The gauge invariance of the imaginary part, on the other hand, sets a severe constraint which is a lattice analogue of the gauge anomaly free condition. For real gauge representations, the imaginary part identically vanishes and the gauge invariance becomes exact.
Baryon resonances from a novel fat-link fermion action
Melnitchouk, W; Bonnet, F D R; Coddington, P D; Leinweber, D B; Williams, A G; Zanotti, J M; Zhang, J B; Lee, F X
2002-01-01
We present first results for masses of positive and negative parity excited baryons in lattice QCD using an O(a^2) improved gluon action and a Fat Link Irrelevant Clover (FLIC) fermion action in which only the irrelevant operators are constructed with fat links. The results are in agreement with earlier calculations of N^* resonances using improved actions and exhibit a clear mass splitting between the nucleon and its chiral partner, even for the Wilson fermion action. The results also indicate a splitting between the lowest J^P = 1/2^- states for the two standard nucleon interpolating fields.
Hadron Masses From Novel Fat-Link Fermion Actions
Zanotti, J M; Bonnet, F D R; Coddington, P D; Lee, F X; Leinweber, D B; Melnitchouk, W; Williams, A G; Zhang, J B
2002-01-01
The hadron mass spectrum is calculated in lattice QCD using a novel fat-link clover fermion action in which only the irrelevant operators in the fermion action are constructed using smeared links. The simulations are performed on a 16^3 x 32 lattice with a lattice spacing of a=0.125 fm. We compare actions with n=4 and 12 smearing sweeps with a smearing fraction of 0.7. The n=4 Fat-Link Irrelevant Clover (FLIC) action provides scaling which is superior to mean-field improvement, and offers advantages over nonperturbative 0(a) improvement, including a reduced exceptional configuration problem.
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)
Anomalous properties of spin-extended chiral fermions
Elbistan, M
2015-01-01
The spin-extended semiclassical chiral fermion (we call the S-model), which had been used to derive the twisted Lorentz symmetry of the "spin-enslaved" chiral chiral fermion (we call the c-model) is equivalent to the latter in the free case, however coupling to an external electromagnetic field yields inequivalent systems. The difference is highlighted by the inconsistency of spin enslavement within the spin-extended framework. The S-model exhibits nevertheless similar though slightly different anomalous properties as the usual c-model does.
High-pressure studies on heavy fermion systems
Institute of Scientific and Technical Information of China (English)
陈晔; 翁宗法; 路欣; 袁辉球
2016-01-01
In this review article, we give a brief overview of heavy fermions, which are prototype examples of strongly correlated electron systems. We introduce the application of physical pressure in heavy fermion systems to construct their pressure phase diagrams and to study the close relationship between superconductivity (SC) and other electronic instabilities, such as antiferromagnetism (AFM), ferromagnetism (FM), and valence transitions. Field-angle dependent heat capacity and point-contact spectroscopic measurements under pressure are taken as examples to illustrate their ability to investigate novel physical properties of the emergent electronic states.
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....
Dynamical fermion masses under the influence of Kaluza-Klein fermions in extra dimensions
Abe, Hiroyuki; Miguchi, Hironori; Muta, Taizo
2000-01-01
The dynamical fermion mass generation in the 4-dimensional brane is discussed in a model with 5-dimensional Kaluza-Klein fermions in interaction with 4-dimensional fermions. It is found that the dynamical fermion masses are generated beyond the critical radius of the compactified extra dimensional space and may be made small compared with masses of the Kaluza-Klein modes.
Dynamical fermion masses under the influence of Kaluza-Klein fermions in extra dimensions
Abe, H; Muta, T; Abe, Hiroyuki; Miguchi, Hironori; Muta, Taizo
2000-01-01
The dynamical fermion mass generation in the 4-dimensional brane is discussedin a model with 5-dimensional Kaluza-Klein fermions in interaction with4-dimensional fermions. It is found that the dynamical fermion masses aregenerated beyond the critical radius of the compactified extra dimensionalspace and may be made small compared with masses of the Kaluza-Klein modes.
Energy Technology Data Exchange (ETDEWEB)
Nakanishi, Y [Department of Materials Science and Engineering, Iwate University, Morioka 020-8551 (Japan); Yoshizawa, M [Department of Materials Science and Engineering, Iwate University, Morioka 020-8551 (Japan); Yamaguchi, T [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Hazama, H [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Nemoto, Y [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Goto, T [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Matsuda, T D [Department of Physics, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); Sugawara, H [Department of Physics, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); Sato, H [Department of Physics, Tokyo Metropolitan University, Hachioji 192-0397 (Japan)
2002-11-18
Ultrasonic measurement on the filled skutterudite compound PrFe{sub 4}P{sub 12} exhibits a mysterious temperature dependence of the elastic constant (C{sub 11} - C{sub 12})/2. Pronounced elastic softening at low temperatures is revived by applying a magnetic field. This fact strongly suggests the 4f-multiplet ground state of the Pr ion split by the crystalline electric field (CEF) to be a {gamma}{sub 3} non-Kramers doublet. The expectation value of a quadrupole moment with {gamma}{sub 3} symmetry in the CEF ground state, which leads to elastic softening at low temperature, was evaluated by theoretical fitting to the present results. This may imply that suppression of the electric quadrupole Kondo effect occurs in PrFe{sub 4}P{sub 12} and the quadrupole moment becomes steady due to the application of a magnetic field. (letter to the editor)
Nakanishi, Y; Yamaguchi, T; Hazama, H; Nemoto, Y; Goto, T; Matsuda, T D; Sugawara, H; Sato, H
2002-01-01
Ultrasonic measurement on the filled skutterudite compound PrFe sub 4 P sub 1 sub 2 exhibits a mysterious temperature dependence of the elastic constant (C sub 1 sub 1 - C sub 1 sub 2)/2. Pronounced elastic softening at low temperatures is revived by applying a magnetic field. This fact strongly suggests the 4f-multiplet ground state of the Pr ion split by the crystalline electric field (CEF) to be a GAMMA sub 3 non-Kramers doublet. The expectation value of a quadrupole moment with GAMMA sub 3 symmetry in the CEF ground state, which leads to elastic softening at low temperature, was evaluated by theoretical fitting to the present results. This may imply that suppression of the electric quadrupole Kondo effect occurs in PrFe sub 4 P sub 1 sub 2 and the quadrupole moment becomes steady due to the application of a magnetic field. (letter to the editor)
Manifestly Gauge Covariant Treatment of Lattice Chiral Fermion
Suzuki, H
1997-01-01
We propose a lattice formulation of the chiral fermion which maximally respects the gauge symmetry and simultaneously is free of the unwanted species doublers. This is achieved by directly dealing with the lattice fermion propagator and the composite operators, rather than the lattice action and the fermionic determinant. The latter is defined as a functional integral of the expectation value of the gauge current operator with respect to the background gauge field. The gauge anomaly is characterized as a non-integrability of this integration process and, the determinant is defined only for anomaly free cases. Gauge singlet operators on the other hand are always regularized gauge invariantly. Some perturbative check is performed to confirm the gauge covariance and the absence of the doublers. This formulation can be applied rather straightforwardly to numerical simulations in the quenched approximation.
The fermion propagator in cosmological spaces with constant deceleration
Energy Technology Data Exchange (ETDEWEB)
Koksma, Jurjen F; Prokopec, Tomislav, E-mail: J.F.Koksma@uu.n, E-mail: T.Prokopec@uu.n [Institute for Theoretical Physics (ITP) and Spinoza Institute, Utrecht University, Postbus 80195, 3508 TD Utrecht (Netherlands)
2009-06-21
We calculate the fermion propagator in Friedmann-LemaItre-Robertson-Walker (FLRW) spacetimes with constant deceleration q=epsilon-1, epsilon=-H-dot/H{sup 2} for excited states. For fermions whose mass is generated by a scalar field through a Yukawa coupling m = g{sub Y}phi, we assume phi approx H. We first solve the mode functions by splitting the spinor into a direct product of helicity and chirality spinors. We also allow for non-vacuum states. We normalize the spinors using a consistent canonical quantization and by requiring orthogonality of particle and anti-particle spinors. We apply our propagator to calculate the one-loop effective action and renormalize using dimensional regularization. Since the Hubble parameter is now treated dynamically, this paves the way to study the dynamical backreaction of fermions on the background spacetime.
Study of Cullum's and Willoughby's Lanczos method for Wilson fermions
Kalkreuter, T
1995-01-01
The Lanczos method of Cullum and Willoughby is studied for euclidean Wilson fermions in quenched and unquenched SU(2) gauge fields on lattices of volume ranging from 4^4 to 16^4. The method is reliable even on larger lattices, but its cost for the computation of a given fraction of the spectrum grows (approximately) with the square of the lattice volume. We investigate the convergence behaviour and show that it is closely linked with the local spectral density. Complete spectra are determined on lattices up to 8^3 \\cdot 12. For configurations where all eigenvalues are computed, we give numerical values for the fermionic determinants and results for spectral densities. Determinants are also given for staggered fermions whose quenched and unquenched spectra were studied in a previous publication.
Study of Cullum's and Willoughby's Lanczos method for Wilson fermions
Kalkreuter, T.
1996-05-01
The Lanczos method of Cullum and Willoughby is studied for euclidean Wilson fermions in quenched and unquenched SU(2) gauge fields on lattices of volume ranging from $4^4$ to $16^4$. The method is reliable even on larger lattices, but its cost for the computation of a given fraction of the spectrum grows (approximately) with the square of the lattice volume. We investigate the convergence behaviour and show that it is closely linked with the local spectral density. Complete spectra are determined on lattices up to $8^3 \\cdot 12$. For configurations where all eigenvalues are computed, we give numerical values for the fermionic determinants and results for spectral densities. Determinants are also given for staggered fermions whose quenched and unquenched spectra were studied in a previous publication.
Mixing of fermions and spectral representation of propagator
Kaloshin, A. E.; Lomov, V. P.
2016-03-01
We develop the spectral representation of propagator for n mixing fermion fields in the case of P-parity violation. The approach based on the eigenvalue problem for inverse matrix propagator makes possible to build the system of orthogonal projectors and to represent the matrix propagator as a sum of poles with positive and negative energies. The procedure of multiplicative renormalization in terms of spectral representation is investigated and the renormalization matrices are obtained in a closed form without the use of perturbation theory. Since in theory with P-parity violation the standard spin projectors do not commute with the dressed propagator, they should be modified. The developed approach allows us to build the modified (dressed) spin projectors for a single fermion and for a system of fermions.
A Three Higgs Doublet Model for Fermion Masses
Chao, Wei
2016-09-01
In this paper we propose a possible explanation to the Fermion mass hierarchy problem by fitting the type-II seesaw mechanism into the Higgs doublet sector, such that their vacuum expectation values are hierarchal. We extend the Standard Model with two extra Higgs doublets as well as a spontaneously broken UX (1) gauge symmetry. All the fermion Yukawa couplings except that of the top quark are of O}(10-2) in our model. Constraints on the parameter space of the model from low energy processes are studied. Besides, the lightest one of the neutral fermion fields, which is introduced to cancel the anomalies of the U(1)X gauge symmetry can be the cold dark matter candidate. We investigate its signature in the dark matter direct detection. Supported in part by the Wisconsin Alumni Research Foundation
Fermion zero modes in a $Z_2$ vortex background
Lozano, Gustavo; Schaposnik, Fidel A
2016-01-01
In this paper we study the zero energy solutions of the Dirac equation in the background of a $Z_2$ vortex of a non-Abelian gauge model with three charged scalar fields. We determine the number of the fermionic zero modes giving their explicit form for two specific Ansatze.
Spectrum of an Elliptic Free Fermionic Corner Transfer Matrix Hamiltonian
Cuerno, R
1993-01-01
The eigenvalues of the Corner Transfer Matrix Hamiltonian associated to the elliptic $R$ matrix of the eight vertex free fermion model are computed in the anisotropic case for magnetic field smaller than the critical value. An argument based on generating functions is given, and the results are checked numerically. The spectrum consists of equally spaced levels.
Free Fermionic Elliptic Reflection Matrices and Quantum Group Invariance
Cuerno, R
1993-01-01
Elliptic diagonal solutions for the reflection matrices associated to the elliptic $R$ matrix of the eight vertex free fermion model are presented. They lead through the second derivative of the open chain transfer matrix to an XY hamiltonian in a magnetic field which is invariant under a quantum deformed Clifford--Hopf algebra.
Functional Integrals and Collective Excitations in Boson-Fermion Model
Institute of Scientific and Technical Information of China (English)
YAN Jun
2006-01-01
In this paper, collective excitations in the boson-fermion model are investigated by means of functional integration method. The equations of energy gap and excitation spectrum are derived. Moreover, the Bose energy spectrum of zero wave vector Fermi fields is also calculated.