Nuclear matter from chiral effective field theory
International Nuclear Information System (INIS)
Drischler, Christian
2017-01-01
Nuclear matter is an ideal theoretical system that provides key insights into the physics of different length scales. While recent ab initio calculations of medium-mass to heavy nuclei have demonstrated that realistic saturation properties in infinite matter are crucial for reproducing experimental binding energies and charge radii, the nuclear-matter equation of state allows tight constraints on key quantities of neutron stars. In the present thesis we take advantage of both aspects. Chiral effective field theory (EFT) with pion and nucleon degrees of freedom has become the modern low-energy approach to nuclear forces based on the symmetries of quantum chromodynamics, the fundamental theory of strong interactions. The systematic chiral expansion enables improvable calculations associated with theoretical uncertainty estimates. In recent years, chiral many-body forces were derived up to high orders, allowing consistent calculations including all many-body contributions at next-to-next-to-next-to-leading order (N 3 LO). Many further advances have driven the construction of novel chiral potentials with different regularization schemes. Here, we develop advanced methods for microscopic calculations of the equation of state of homogeneous nuclear matter with arbitrary proton-to-neutron ratio at zero temperature. Specifically, we push the limits of many-body perturbation theory (MBPT) considerations to high orders in the chiral and in the many-body expansion. To address the challenging inclusion of three-body forces, we introduce a new partial-wave method for normal ordering that generalizes the treatment of these contributions. We show improved predictions for the neutron-matter equation of state with consistent N 3 LO nucleon-nucleon (NN) plus three-nucleon (3N) potentials using MBPT up to third order and self-consistent Green's function theory. The latter also provides nonperturbative benchmarks for the many-body convergence. In addition, we extend the normal
Nuclear matter from chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Drischler, Christian
2017-11-15
Nuclear matter is an ideal theoretical system that provides key insights into the physics of different length scales. While recent ab initio calculations of medium-mass to heavy nuclei have demonstrated that realistic saturation properties in infinite matter are crucial for reproducing experimental binding energies and charge radii, the nuclear-matter equation of state allows tight constraints on key quantities of neutron stars. In the present thesis we take advantage of both aspects. Chiral effective field theory (EFT) with pion and nucleon degrees of freedom has become the modern low-energy approach to nuclear forces based on the symmetries of quantum chromodynamics, the fundamental theory of strong interactions. The systematic chiral expansion enables improvable calculations associated with theoretical uncertainty estimates. In recent years, chiral many-body forces were derived up to high orders, allowing consistent calculations including all many-body contributions at next-to-next-to-next-to-leading order (N{sup 3}LO). Many further advances have driven the construction of novel chiral potentials with different regularization schemes. Here, we develop advanced methods for microscopic calculations of the equation of state of homogeneous nuclear matter with arbitrary proton-to-neutron ratio at zero temperature. Specifically, we push the limits of many-body perturbation theory (MBPT) considerations to high orders in the chiral and in the many-body expansion. To address the challenging inclusion of three-body forces, we introduce a new partial-wave method for normal ordering that generalizes the treatment of these contributions. We show improved predictions for the neutron-matter equation of state with consistent N{sup 3}LO nucleon-nucleon (NN) plus three-nucleon (3N) potentials using MBPT up to third order and self-consistent Green's function theory. The latter also provides nonperturbative benchmarks for the many-body convergence. In addition, we extend the
Hyperon-nucleon interactions - a chiral effective field theory approach
Polinder, H.; Haidenbauer, J.; Meissner, U.G.
2006-01-01
We construct the leading order hyperon–nucleon potential in chiral effective field theory. We show that a good description of the available data is possible and discuss briefly further improvements of this scheme
Scattering of decuplet baryons in chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Haidenbauer, J. [Institut fuer Kernphysik, Institute for Advanced Simulation and Juelich Center for Hadron Physics, Juelich (Germany); Petschauer, S.; Kaiser, N.; Weise, W. [Technische Universitaet Muenchen, Physik Department, Garching (Germany); Meissner, Ulf G. [Institut fuer Kernphysik, Institute for Advanced Simulation and Juelich Center for Hadron Physics, Juelich (Germany); Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany)
2017-11-15
A formalism for treating the scattering of decuplet baryons in chiral effective field theory is developed. The minimal Lagrangian and potentials in leading-order SU(3) chiral effective field theory for the interactions of octet baryons (B) and decuplet baryons (D) for the transitions BB → BB, BB <-> DB, DB → DB, BB <-> DD, DB <-> DD, and DD → DD are provided. As an application of the formalism we compare with results from lattice QCD simulations for ΩΩ and NΩ scattering. Implications of our results pertinent to the quest for dibaryons are discussed. (orig.)
Nuclear Lattice Simulations with Chiral Effective Field Theory
Lee, Dean
2008-01-01
We present recent results on lattice simulations using chiral effective field theory. In particular we discuss lattice simulations for dilute neutron matter at next-to-leading order and three-body forces in light nuclei at next-to-next-to-leading order.
Quantum Monte Carlo calculations with chiral effective field theory interactions
Energy Technology Data Exchange (ETDEWEB)
Tews, Ingo
2015-10-12
The neutron-matter equation of state connects several physical systems over a wide density range, from cold atomic gases in the unitary limit at low densities, to neutron-rich nuclei at intermediate densities, up to neutron stars which reach supranuclear densities in their core. An accurate description of the neutron-matter equation of state is therefore crucial to describe these systems. To calculate the neutron-matter equation of state reliably, precise many-body methods in combination with a systematic theory for nuclear forces are needed. Chiral effective field theory (EFT) is such a theory. It provides a systematic framework for the description of low-energy hadronic interactions and enables calculations with controlled theoretical uncertainties. Chiral EFT makes use of a momentum-space expansion of nuclear forces based on the symmetries of Quantum Chromodynamics, which is the fundamental theory of strong interactions. In chiral EFT, the description of nuclear forces can be systematically improved by going to higher orders in the chiral expansion. On the other hand, continuum Quantum Monte Carlo (QMC) methods are among the most precise many-body methods available to study strongly interacting systems at finite densities. They treat the Schroedinger equation as a diffusion equation in imaginary time and project out the ground-state wave function of the system starting from a trial wave function by propagating the system in imaginary time. To perform this propagation, continuum QMC methods require as input local interactions. However, chiral EFT, which is naturally formulated in momentum space, contains several sources of nonlocality. In this Thesis, we show how to construct local chiral two-nucleon (NN) and three-nucleon (3N) interactions and discuss results of first QMC calculations for pure neutron systems. We have performed systematic auxiliary-field diffusion Monte Carlo (AFDMC) calculations for neutron matter using local chiral NN interactions. By
Nuclear electric dipole moments in chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Bsaisou, J.; Vries, J. de [Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); Hanhart, C. [Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); JARA - Forces and Matter Experiments,Forschungszentrum Jülich, D-52425 Jülich (Germany); Liebig, S. [Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); Meißner, Ulf-G. [Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); JARA - Forces and Matter Experiments,Forschungszentrum Jülich, D-52425 Jülich (Germany); JARA - High Performance Computing,Forschungszentrum Jülich, D-52425 Jülich (Germany); Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics,Universität Bonn,D-53115 Bonn (Germany); Minossi, D. [Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); Nogga, A.; Wirzba, A. [Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); JARA - Forces and Matter Experiments,Forschungszentrum Jülich, D-52425 Jülich (Germany)
2015-03-19
We provide a consistent and complete calculation of the electric dipole moments of the deuteron, helion, and triton in the framework of chiral effective field theory. The CP-conserving and CP-violating interactions are treated on equal footing and we consider CP-violating one-, two-, and three-nucleon operators up to next-to-leading-order in the chiral power counting. In particular, we calculate for the first time EDM contributions induced by the CP-violating three-pion operator. We find that effects of CP-violating nucleon-nucleon contact interactions are larger than those found in previous studies based on phenomenological models for the CP-conserving nucleon-nucleon interactions. Our results which apply to any model of CP violation in the hadronic sector can be used to test various scenarios of CP violation. As examples, we study the implications of our results on the QCD θ-term and the minimal left-right symmetric model.
Hyperons in nuclear matter from SU(3) chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Petschauer, S.; Kaiser, N. [Technische Universitaet Muenchen, Physik Department, Garching (Germany); Haidenbauer, J. [Institut fuer Kernphysik, Forschungszentrum Juelich, Institute for Advanced Simulation, Juelich Center for Hadron Physics, Juelich (Germany); Meissner, Ulf G. [Institut fuer Kernphysik, Forschungszentrum Juelich, Institute for Advanced Simulation, Juelich Center for Hadron Physics, Juelich (Germany); Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Weise, W. [Technische Universitaet Muenchen, Physik Department, Garching (Germany); Villa Tambosi, ECT, Villazzano (Trento) (Italy)
2016-01-15
Brueckner theory is used to investigate the properties of hyperons in nuclear matter. The hyperon-nucleon interaction is taken from chiral effective field theory at next-to-leading order with SU(3) symmetric low-energy constants. Furthermore, the underlying nucleon-nucleon interaction is also derived within chiral effective field theory. We present the single-particle potentials of Λ and Σ hyperons in symmetric and asymmetric nuclear matter computed with the continuous choice for intermediate spectra. The results are in good agreement with the empirical information. In particular, our calculation gives a repulsive Σ-nuclear potential and a weak Λ-nuclear spin-orbit force. (orig.)
Baryonic forces and hyperons in nuclear matter from SU(3) chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Petschauer, Stefan Karl
2016-02-12
In this work the baryon-baryon interaction is studied at next-to-leading order in SU(3) chiral effective field theory and applied to hyperon-nucleon scattering. The properties of hyperons in isospin-symmetric as well as asymmetric nuclear matter are calculated within the Bruecker-Hartree-Fock formalism. Moreover, the leading three-baryon interaction is derived and its low-energy constants are estimated from decuplet intermediate states. We conclude, that chiral effective field theory is a well-suited tool to describe the baryonic forces.
Spin-polarized neutron matter at different orders of chiral effective field theory
Sammarruca, F.; Machleidt, R.; Kaiser, N.
2015-01-01
Spin-polarized neutron matter is studied using chiral two- and three-body forces. We focus, in particular, on predictions of the energy per particle in ferromagnetic neutron matter at different orders of chiral effective field theory and for different choices of the resolution scale. We discuss the convergence pattern of the predictions and their cutoff dependence. We explore to which extent fully polarized neutron matter behaves (nearly) like a free Fermi gas. We also consider the more gener...
The gamma N ---> Delta transition in chiral effective-field theory.
Energy Technology Data Exchange (ETDEWEB)
Vladimir Pascalutsa; Marc Vanderhaeghen
2006-04-27
We describe the pion electroproduction processes in the {Delta}(1232)-resonance region within the framework of chiral effective-field theory. By studying the observables of pion electroproduction in a next-to-leading order calculation we are able to make predictions and draw conclusions on the properties of the N {yields} {Delta} electromagnetic form factors.
The $\\gamma N\\to \\De$ transition in chiral effective-field theory
Energy Technology Data Exchange (ETDEWEB)
Vladimir Pascalutsa; Marc Vanderhaeghen
2006-04-27
We describe the pion electroproduction processes in the {Delta}(1232)-resonance region within the framework of chiral effective-field theory. By studying the observables of pion electroproduction in a next-to-leading order calculation we are able to make predictions and draw conclusions on the properties of the N {yields} {Delta} electromagnetic form factors.
Strangeness S = -2 baryon-baryon interactions using chiral effective field theory
Polinder, H.; Haidenbauer, J.; Meissner, U.G.
2007-01-01
We derive the leading order strangeness S =−2 baryon–baryon interactions in chiral effective field theory. The potential consists of contact terms without derivatives and of one-pseudoscalar-meson exchanges. The contact terms and the couplings of the pseudoscalar mesons to the baryons are related
Chiral effective-field theory of the nucleon spin structure
Pascalutsa, Vladimir
2017-01-01
I will review the recent chiral EFT calculations of the nucleon (spin) structure functions at low Q2, confronted with the Jefferson Lab measurements. The moments of the structure functions correspond with various polarizabilities, and I will explain why one of them - δLT - is especially interesting. I will also discuss how the spin structure functions at low Q enter in the atomic calculations of the hyperfine splittings and how they are impacting the ongoing experimental program at PSI (Switzerland) to measure the ground-state hyperfine splitting of muonic hydrogen. Partially supported by the Deutsche Forschungsgemeinschaft (DFG) through the Collaborative Research Center SFB 1044 [The Low-Energy Frontier of the Standard Model].
Towards a chiral effective field theory of nuclear matter
International Nuclear Information System (INIS)
Mallik, S.
2008-01-01
As a preliminary attempt to formulate an effective theory of nuclear matter, we undertake to calculate the effective pole parameters of nucleon in such a medium. We begin with the virial expansion of these parameters to leading order in nucleon number density in terms of the on-shell NN scattering amplitude. We then proceed to calculate the same parameters in the effective theory, getting a formula for the nucleon mass-shift to leading order, that was known already to give too large a value to be acceptable at normal nuclear density. At this point the virial expansion suggests a modification of this formula, which we carry out following Weinberg's method for the two-nucleon system in the effective theory. The results are encouraging enough to attempt a complete, next-to-leading order calculation of the off-shell nucleon spectral function in nuclear medium. (author)
Hyperons in nuclear matter from SU(3) chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Petschauer, Stefan; Kaiser, Norbert [Technische Universitaet Muenchen (Germany); Haidenbauer, Johann [Forschungszentrum Juelich (Germany); Meissner, Ulf G. [Forschungszentrum Juelich (Germany); Universitaet Bonn (Germany); Weise, Wolfram [Technische Universitaet Muenchen (Germany); ECT, Trento (Italy)
2016-07-01
Brueckner theory is used to investigate the properties of hyperons in nuclear matter. The hyperon-nucleon interaction is taken from chiral effective field theory at next-to-leading order with SU(3) symmetric low-energy constants. Furthermore, the underlying nucleon-nucleon interaction is also derived within chiral effective field theory. We present the single-particle potentials of Λ and Σ hyperons in symmetric and asymmetric nuclear matter computed with the continuous choice for intermediate spectra. The results are in good agreement with the empirical information. In particular, our calculation gives a repulsive Σ-nuclear potential and a weak Λ-nuclear spin-orbit force. The splittings among the Σ{sup +}, Σ{sup 0} and Σ{sup -} potentials have a non-linear dependence on the isospin asymmetry which goes beyond the usual parametrization in terms of an isovector Lane potential.
Energy Technology Data Exchange (ETDEWEB)
Hilt, Marius
2011-12-13
This thesis is concerned with pion photoproduction (PPP) and pion electroproduction (PEP) in the framework of manifestly Lorentz-invariant baryon chiral perturbation theory. For that purpose two different approaches are used. Firstly, a one-loop-order calculation up to chiral order O(q{sup 4}) including pions and nucleons as degrees of freedom, is performed to describe the energy dependence of the reactions over a large range. To improve the dependence on the virtuality of the photon in PEP, in a second approach vector mesons are included as explicit degrees of freedom. The latter calculation includes one-loop contributions up to chiral order O(q{sup 3}). Only three of the four physical processes of PPP and PEP can be accessed experimentally. These reactions are measured at several different facilities, e.g. Mainz, Bonn, or Saskatoon. The data obtained there are used to explore the limits of chiral perturbation theory. This thesis is the first complete manifestly Lorentz-invariant calculation up to order O(q{sup 4}) for PPP and PEP, and the first calculation ever for these processes including vector mesons explicitly. Beside the calculation of physical observables, a partial wave decomposition is performed and the most important multipoles are analyzed. They may be extracted from the calculated amplitudes and allow one to examine the nucleon and {delta} resonances. The number of diagrams one has to calculate is very large. In order to handle these expressions, several routines were developed for the computer algebra system Mathematica. For the multipole decomposition, two different programs are used. On the one hand, a modified version of the so-called {chi}MAID has been employed. On the other hand, similar routines were developed for Mathematica. In the end, the different calculations are compared with respect to their applicability to PPP and PEP.
Chiral effective field theory on the lattice at next-to-leading order
International Nuclear Information System (INIS)
Borasoy, B.; Epelbaum, E.; Krebs, H.; Meissner, U.G.; Lee, D.
2008-01-01
We study nucleon-nucleon scattering on the lattice at next-to-leading order in chiral effective field theory. We determine phase shifts and mixing angles from the properties of two-nucleon standing waves induced by a hard spherical wall in the center-of-mass frame. At fixed lattice spacing we test model independence of the low-energy effective theory by computing next-to-leading-order corrections for two different leading-order lattice actions. The first leading-order action includes instantaneous one-pion exchange and same-site contact interactions. The second leading-order action includes instantaneous one-pion exchange and Gaussian-smeared interactions. We find that in each case the results at next-to-leading order are accurate up to corrections expected at higher order. (orig.)
Lim, Yeunhwan; Holt, Jeremy W.
2017-06-01
We investigate the structure of neutron star crusts, including the crust-core boundary, based on new Skyrme mean field models constrained by the bulk-matter equation of state from chiral effective field theory and the ground-state energies of doubly-magic nuclei. Nuclear pasta phases are studied using both the liquid drop model as well as the Thomas-Fermi approximation. We compare the energy per nucleon for each geometry (spherical nuclei, cylindrical nuclei, nuclear slabs, cylindrical holes, and spherical holes) to obtain the ground state phase as a function of density. We find that the size of the Wigner-Seitz cell depends strongly on the model parameters, especially the coefficients of the density gradient interaction terms. We employ also the thermodynamic instability method to check the validity of the numerical solutions based on energy comparisons.
Two-nucleon S10 amplitude zero in chiral effective field theory
Sánchez, M. Sánchez; Yang, C.-J.; Long, Bingwei; van Kolck, U.
2018-02-01
We present a new rearrangement of short-range interactions in the S10 nucleon-nucleon channel within chiral effective field theory. This is intended to address the slow convergence of Weinberg's scheme, which we attribute to its failure to reproduce the amplitude zero (scattering momentum ≃340 MeV) at leading order. After the power counting scheme is modified to accommodate the zero at leading order, it includes subleading corrections perturbatively in a way that is consistent with renormalization-group invariance. Systematic improvement is shown at next-to-leading order, and we obtain results that fit empirical phase shifts remarkably well all the way up to the pion-production threshold. An approach in which pions have been integrated out is included, which allows us to derive analytic results that also fit phenomenology surprisingly well.
International Nuclear Information System (INIS)
Koelling, S.; Epelbaum, E.; Krebs, H.; Meissner, U.-G.
2011-01-01
We derive the leading one-loop contribution to the one-pion exchange and short-range two-nucleon electromagnetic current operator in the framework of chiral effective field theory. The derivation is carried out using the method of unitary transformation. Explicit results for the current and charge densities are given in momentum and coordinate space.
Alarcón, J. M.; Weiss, C.
2018-05-01
We study the nucleon electromagnetic form factors (EM FFs) using a recently developed method combining chiral effective field theory (χ EFT ) and dispersion analysis. The spectral functions on the two-pion cut at t >4 Mπ2 are constructed using the elastic unitarity relation and an N /D representation. χ EFT is used to calculate the real functions J±1(t ) =f±1(t ) /Fπ(t ) (ratios of the complex π π →N N ¯ partial-wave amplitudes and the timelike pion FF), which are free of π π rescattering. Rescattering effects are included through the empirical timelike pion FF | Fπ(t) | 2 . The method allows us to compute the isovector EM spectral functions up to t ˜1 GeV2 with controlled accuracy (leading order, next-to-leading order, and partial next-to-next-to-leading order). With the spectral functions we calculate the isovector nucleon EM FFs and their derivatives at t =0 (EM radii, moments) using subtracted dispersion relations. We predict the values of higher FF derivatives, which are not affected by higher-order chiral corrections and are obtained almost parameter-free in our approach, and explain their collective behavior. We estimate the individual proton and neutron FFs by adding an empirical parametrization of the isoscalar sector. Excellent agreement with the present low-Q2 FF data is achieved up to ˜0.5 GeV2 for GE, and up to ˜0.2 GeV2 for GM. Our results can be used to guide the analysis of low-Q2 elastic scattering data and the extraction of the proton charge radius.
Equation of state of neutron-rich nuclear matter from chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Kaiser, Norbert; Strohmeier, Susanne [Technische Universitaet Muenchen (Germany)
2016-07-01
Based on chiral effective field theory, the equation of state of neutron-rich nuclear matter is investigated systematically. The contributing diagrams include one- and two-pion exchange together with three-body terms arising from virtual Δ(1232)-isobar excitations. The proper expansion of the energy per particle, anti E(k{sub f},δ) = anti E{sub n}(k{sub f}) + δB{sub 1}(k{sub f}) + δ{sup 5/3}B{sub 5/3}(k{sub f}) + δ{sup 2}B{sub 2}(k{sub f}) +.., for the system with neutron density ρ{sub n} = k{sub f}{sup 3}(1-δ)/3π{sup 2} and proton density ρ{sub p} = k{sub f}{sup 3}δ/3π{sup 2} is performed analytically for the various interaction contributions. One observes essential structural differences to the commonly used quadratic approximation. The density dependent coefficient B{sub 1}(k{sub f}) turns out to be unrelated to the isospin-asymmetry of nuclear matter. The coefficient B{sub 5/3}(k{sub f}) of the non-analytical δ{sup 5/3}-term receives contributions from the proton kinetic energy and from the one- and two-pion exchange interactions. The physical consequences for neutron star matter are studied.
Energy Technology Data Exchange (ETDEWEB)
Krueger, Thomas
2016-10-19
The physics of neutron-rich systems is of great interest in nuclear and astrophysics. Precise knowledge of the properties of neutron-rich nuclei is crucial for understanding the synthesis of heavy elements. Infinite neutron matter determines properties of neutron stars, a final stage of heavy stars after a core-collapse supernova. It also provides a unique theoretical laboratory for nuclear forces. Strong interactions are determined by quantum chromodynamics (QCD). However, QCD is non-perturbative at low energies and one presently cannot directly calculate nuclear forces from it. Chiral effective field theory circumvents these problems and connects the symmetries of QCD to nuclear interactions. It naturally and systematically includes many-nucleon forces and gives access to uncertainty estimates. We use chiral interactions throughout all calculation in this thesis. Neutron stars are very extreme objects. The densities in their interior greatly exceed those in nuclei. The exact composition and properties of neutron stars is still unclear but they consist mainly of neutrons. One can explore neutron stars theoretically with calculations of neutron matter. In the inner core of neutron stars exist very high densities and thus maybe exotic phases of matter. To investigate whether there exists a phase transition to such phases even at moderate densities we study the chiral condensate in neutron matter, the order parameter of chiral symmetry breaking, and find no evidence for a phase transition at nuclear densities. We also calculate the more extreme system of spin-polarised neutron matter. With this we address the question whether there exists such a polarised phase in neutron stars and also provide a benchmark system for lattice QCD. We find spin-polarised neutron matter to be an almost non-interacting Fermi gas. To understand the cooling of neutron stars neutron pairing is of great importance. Due to the high densities especially triplet pairing is of interest. We
Uncertainty quantification for proton–proton fusion in chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Acharya, B. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Carlsson, B.D. [Department of Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Ekström, A. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Department of Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Forssén, C. [Department of Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Platter, L., E-mail: lplatter@utk.edu [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
2016-09-10
We compute the S-factor of the proton–proton (pp) fusion reaction using chiral effective field theory (χEFT) up to next-to-next-to-leading order (NNLO) and perform a rigorous uncertainty analysis of the results. We quantify the uncertainties due to (i) the computational method used to compute the pp cross section in momentum space, (ii) the statistical uncertainties in the low-energy coupling constants of χEFT, (iii) the systematic uncertainty due to the χEFT cutoff, and (iv) systematic variations in the database used to calibrate the nucleon–nucleon interaction. We also examine the robustness of the polynomial extrapolation procedure, which is commonly used to extract the threshold S-factor and its energy-derivatives. By performing a statistical analysis of the polynomial fit of the energy-dependent S-factor at several different energy intervals, we eliminate a systematic uncertainty that can arise from the choice of the fit interval in our calculations. In addition, we explore the statistical correlations between the S-factor and few-nucleon observables such as the binding energies and point-proton radii of {sup 2,3}H and {sup 3}He as well as the D-state probability and quadrupole moment of {sup 2}H, and the β-decay of {sup 3}H. We find that, with the state-of-the-art optimization of the nuclear Hamiltonian, the statistical uncertainty in the threshold S-factor cannot be reduced beyond 0.7%.
Cirigliano, V.; Dekens, W.; de Vries, J.; Graesser, M. L.; Mereghetti, E.
2017-12-01
We analyze neutrinoless double beta decay (0 νββ) within the framework of the Standard Model Effective Field Theory. Apart from the dimension-five Weinberg operator, the first contributions appear at dimension seven. We classify the operators and evolve them to the electroweak scale, where we match them to effective dimension-six, -seven, and -nine operators. In the next step, after renormalization group evolution to the QCD scale, we construct the chiral Lagrangian arising from these operators. We develop a power-counting scheme and derive the two-nucleon 0 νββ currents up to leading order in the power counting for each lepton-number-violating operator. We argue that the leading-order contribution to the decay rate depends on a relatively small number of nuclear matrix elements. We test our power counting by comparing nuclear matrix elements obtained by various methods and by different groups. We find that the power counting works well for nuclear matrix elements calculated from a specific method, while, as in the case of light Majorana neutrino exchange, the overall magnitude of the matrix elements can differ by factors of two to three between methods. We calculate the constraints that can be set on dimension-seven lepton-number-violating operators from 0 νββ experiments and study the interplay between dimension-five and -seven operators, discussing how dimension-seven contributions affect the interpretation of 0 νββ in terms of the effective Majorana mass m ββ .
Tews, I.; Carlson, J.; Gandolfi, S.; Reddy, S.
2018-06-01
The dense matter equation of state (EOS) determines neutron star (NS) structure but can be calculated reliably only up to one to two times the nuclear saturation density, using accurate many-body methods that employ nuclear interactions from chiral effective field theory constrained by scattering data. In this work, we use physically motivated ansatzes for the speed of sound c S at high density to extend microscopic calculations of neutron-rich matter to the highest densities encountered in stable NS cores. We show how existing and expected astrophysical constraints on NS masses and radii from X-ray observations can constrain the speed of sound in the NS core. We confirm earlier expectations that c S is likely to violate the conformal limit of {c}S2≤slant {c}2/3, possibly reaching values closer to the speed of light c at a few times the nuclear saturation density, independent of the nuclear Hamiltonian. If QCD obeys the conformal limit, we conclude that the rapid increase of c S required to accommodate a 2 M ⊙ NS suggests a form of strongly interacting matter where a description in terms of nucleons will be unwieldy, even between one and two times the nuclear saturation density. For typical NSs with masses in the range of 1.2–1.4 M ⊙, we find radii between 10 and 14 km, and the smallest possible radius of a 1.4 M ⊙ NS consistent with constraints from nuclear physics and observations is 8.4 km. We also discuss how future observations could constrain the EOS and guide theoretical developments in nuclear physics.
Czech Academy of Sciences Publication Activity Database
Adam, Jiří; Tater, Miloš; Truhlík, Emil; Epelbaum, E.; Machleidt, R.; Ricci, P.
2012-01-01
Roč. 709, 1-2 (2012), s. 93-100 ISSN 0370-2693 R&D Projects: GA MŠk LC06002; GA ČR GAP203/11/0701 Institutional support: RVO:61389005 Keywords : negative muon capture * deuteron * effective field theory * meson exchange currents Subject RIV: BE - Theoretical Physics Impact factor: 4.569, year: 2012
Neutron matter at next-to-next-to-next-to-leading order in chiral effective field theory.
Tews, I; Krüger, T; Hebeler, K; Schwenk, A
2013-01-18
Neutron matter presents a unique system for chiral effective field theory because all many-body forces among neutrons are predicted to next-to-next-to-next-to-leading order (N(3)LO). We present the first complete N(3)LO calculation of the neutron matter energy. This includes the subleading three-nucleon forces for the first time and all leading four-nucleon forces. We find relatively large contributions from N(3)LO three-nucleon forces. Our results provide constraints for neutron-rich matter in astrophysics with controlled theoretical uncertainties.
Dai, Ling-Yun; Haidenbauer, Johann; Meißner, Ulf-G.
2017-07-01
Results for the antinucleon-nucleon (\\overline{N}N) interaction obtained at next-to-next-to-next-to-leading order in chiral effective field theory (EFT) are reported. A new local regularization scheme is used for the pion-exchange contributions that has been recently suggested and applied in a pertinent study of the N N force within chiral EFT. Furthermore, an alternative strategy for estimating the uncertainty is utilized that no longer depends on a variation of the cutoffs. The low-energy constants associated with the arising contact terms are fixed by a fit to the phase shifts and inelasticities provided by a phase-shift analysis of \\overline{p}p scattering data. An excellent description of the \\overline{N}N amplitudes is achieved at the highest order considered. Moreover, because of the quantitative reproduction of partial waves up to J = 3, there is also a nice agreement on the level of \\overline{p}p observables. Specifically, total and integrated elastic and charge-exchange cross sections agree well with the results from the partial-wave analysis up to laboratory energies of 300 MeV, while differential cross sections and analyzing powers are described quantitatively up to 200-250 MeV. The low-energy structure of the \\overline{N}N amplitudes is also considered and compared to data from antiprotonic hydrogen.
International Nuclear Information System (INIS)
Gebremariam, B.; Bogner, S.K.; Duguet, T.
2011-01-01
The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyrme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in (arXiv:0910.4979) by Gebremariam et al. to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N 2 LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a coupling constant arising from zero-range contact interactions and a coupling function of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions are added to standard empirical Skyrme functionals, and the density-independent Skyrme parameters subsequently refit to data. A link to a downloadable Mathematica notebook containing the novel density-dependent couplings is provided.
Electric dipole moments of light nuclei in chiral effective field theory
International Nuclear Information System (INIS)
Bsaisou, Jan
2014-01-01
Electric dipole moments (EDMs) break parity (P) and time-reversal (T) symmetry and thus, by the CPT theorem, CP-symmetry. Once measured, they will be unambiguous signs of new physics since CP violation from the complex phase of the Cabibbo-Kobayashi-Maskawa matrix in the Standard Model predicts EDMs that are experimentally inaccessible in the foreseeable future. The θ-term of Quantum Chromodynamics (QCD) and extensions of the Standard Model such as supersymmetry and multi-Higgs scenarios comprise P- and T-violating interactions which are capable of inducing significantly larger EDMs. The extensions of the Standard Model give rise to a set of effective non-renormalizable operators of canonical dimension six at energies Λ had >or similar 1 GeV when the heavy degrees of freedom are integrated out. The effective dimension-six operators are known as the quark EDM, the quark-chromo EDM, four-quark left-right operator, the gluon-chromo EDM and the four-quark operator. Starting from the QCD θ-term and this set of P- and T-violating effective dimension-six operators, we present a scheme to derive the induced effective Lagrangians at energies below Λ QCD ∝ 200 MeV within the framework of Chiral Perturbation Theory (ChPT) for two quark flavors in the formulation of Gasser and Leutwyler. The differences among the sources of P and T violation manifest themselves at energies below Λ QCD in specific hierarchies of coupling constants of P- and T-violating vertices. We compute the relevant coupling constants of P- and T-violating hadronic vertices which are induced by the QCD θ-term with well-defined uncertainties as functions of the parameter anti θ. The relevant coupling constants induced by the effective dimension-six operators are given as functions of yet unknown Low Energy Constants (LECs) which can not be determined within the framework of ChPT itself. Since the required supplementary input from e.g. Lattice QCD is not yet available, we present Naive Dimensional
Electric dipole moments of light nuclei in chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Bsaisou, Jan
2014-04-25
Electric dipole moments (EDMs) break parity (P) and time-reversal (T) symmetry and thus, by the CPT theorem, CP-symmetry. Once measured, they will be unambiguous signs of new physics since CP violation from the complex phase of the Cabibbo-Kobayashi-Maskawa matrix in the Standard Model predicts EDMs that are experimentally inaccessible in the foreseeable future. The θ-term of Quantum Chromodynamics (QCD) and extensions of the Standard Model such as supersymmetry and multi-Higgs scenarios comprise P- and T-violating interactions which are capable of inducing significantly larger EDMs. The extensions of the Standard Model give rise to a set of effective non-renormalizable operators of canonical dimension six at energies Λ{sub had} >or similar 1 GeV when the heavy degrees of freedom are integrated out. The effective dimension-six operators are known as the quark EDM, the quark-chromo EDM, four-quark left-right operator, the gluon-chromo EDM and the four-quark operator. Starting from the QCD θ-term and this set of P- and T-violating effective dimension-six operators, we present a scheme to derive the induced effective Lagrangians at energies below Λ{sub QCD} ∝ 200 MeV within the framework of Chiral Perturbation Theory (ChPT) for two quark flavors in the formulation of Gasser and Leutwyler. The differences among the sources of P and T violation manifest themselves at energies below Λ{sub QCD} in specific hierarchies of coupling constants of P- and T-violating vertices. We compute the relevant coupling constants of P- and T-violating hadronic vertices which are induced by the QCD θ-term with well-defined uncertainties as functions of the parameter anti θ. The relevant coupling constants induced by the effective dimension-six operators are given as functions of yet unknown Low Energy Constants (LECs) which can not be determined within the framework of ChPT itself. Since the required supplementary input from e.g. Lattice QCD is not yet available, we present Naive
Nuclear axial current operators to fourth order in chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Krebs, H., E-mail: hermann.krebs@rub.de [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Epelbaum, E., E-mail: evgeny.epelbaum@rub.de [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93016 (United States); Meißner, U.-G., E-mail: meissner@hiskp.uni-bonn.de [Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Institut für Kernphysik, Institute for Advanced Simulation, and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); JARA - High Performance Computing, Forschungszentrum Jülich, D-52425 Jülich (Germany)
2017-03-15
We present the complete derivation of the nuclear axial charge and current operators as well as the pseudoscalar operators to fourth order in the chiral expansion relative to the dominant one-body contribution using the method of unitary transformation. We demonstrate that the unitary ambiguity in the resulting operators can be eliminated by the requirement of renormalizability and by matching of the pion-pole contributions to the nuclear forces. We give expressions for the renormalized single-, two- and three-nucleon contributions to the charge and current operators and pseudoscalar operators including the relevant relativistic corrections. We also verify explicitly the validity of the continuity equation.
Tensor Fermi liquid parameters in nuclear matter from chiral effective field theory
Holt, J. W.; Kaiser, N.; Whitehead, T. R.
2018-05-01
We compute from chiral two- and three-body forces the complete quasiparticle interaction in symmetric nuclear matter up to twice nuclear matter saturation density. Second-order perturbative contributions that account for Pauli blocking and medium polarization are included, allowing for an exploration of the full set of central and noncentral operator structures permitted by symmetries and the long-wavelength limit. At the Hartree-Fock level, the next-to-next-to-leading order three-nucleon force contributes to all noncentral interactions, and their strengths grow approximately linearly with the nucleon density up to that of saturated nuclear matter. Three-body forces are shown to enhance the already strong proton-neutron effective tensor interaction, while the corresponding like-particle tensor force remains small. We also find a large isovector cross-vector interaction but small center-of-mass tensor interactions in the isoscalar and isovector channels. The convergence of the expansion of the noncentral quasiparticle interaction in Landau parameters and Legendre polynomials is studied in detail.
International Nuclear Information System (INIS)
Ecker, G.
1996-06-01
After a general introduction to the structure of effective field theories, the main ingredients of chiral perturbation theory are reviewed. Applications include the light quark mass ratios and pion-pion scattering to two-loop accuracy. In the pion-nucleon system, the linear σ model is contrasted with chiral perturbation theory. The heavy-nucleon expansion is used to construct the effective pion-nucleon Lagrangian to third order in the low-energy expansion, with applications to nucleon Compton scattering. (author)
An introduction to effective field theory
International Nuclear Information System (INIS)
Donoghue, John F.
1999-01-01
In these lectures I describe the main ideas of effective field theory. These are first illustrated using QED and the linear sigma model as examples. Calculational techniques using both Feynman diagrams and dispersion relations are introduced. Within QCD, chiral perturbation theory is a complete effective field theory, and I give a guide to some calculations in the literature which illustrates key ideas. (author)
Kohno, M.
2018-03-01
Adopting hyperon-nucleon and hyperon-nucleon-nucleon interactions parametrized in chiral effective field theory, single-particle potentials of the Λ and Σ hyperons are evaluated in symmetric nuclear matter and in pure neutron matter within the framework of lowest-order Bruckner theory. The chiral NLO interaction bears strong Λ N -Σ N coupling. Although the Λ potential is repulsive if the coupling is switched off, the Λ N -Σ N correlation brings about the attraction consistent with empirical data. The Σ potential is repulsive, which is also consistent with empirical information. The interesting result is that the Λ potential becomes shallower beyond normal density. This provides the possibility of solving the hyperon puzzle without introducing ad hoc assumptions. The effects of the Λ N N -Λ N N and Λ N N -Σ N N three-baryon forces are considered. These three-baryon forces are first reduced to normal-ordered effective two-baryon interactions in nuclear matter and then incorporated in the G -matrix equation. The repulsion from the Λ N N -Λ N N interaction is of the order of 5 MeV at normal density and becomes larger with increasing density. The effects of the Λ N N -Σ N N coupling compensate the repulsion at normal density. The net effect of the three-baryon interactions on the Λ single-particle potential is repulsive at higher densities.
International Nuclear Information System (INIS)
Harada, Masayasu
2009-01-01
Chiral perturbation theory has been used for great number of phenomenological analyses in low energy QCD as well as the lattice QCD analyses since the creation of the theory by Weinberg in 1979 followed by its consolidation by Gasser and Leutwyler in 1984 and 85. The theory is now the highly established one as the approach based on the effective field theory to search for Green function including quantum correlations in the frame of the systematic expansion technique using Lagrangian which includes all of the terms allowed by the symmetry. This review has been intended to describe how systematically physical quantities are calculated in the framework of the chiral symmetry. Consequently many of the various phenomenological analyses are not taken up here for which other reports are to be referred. Further views are foreseen to be developed based on the theory in addition to numbers of results reported up to the present. Finally π-π scattering is taken up to discuss to what energy scale the theory is available. (S. Funahashi)
Holographic effective field theories
Energy Technology Data Exchange (ETDEWEB)
Martucci, Luca [Dipartimento di Fisica ed Astronomia “Galileo Galilei' , Università di Padova,and INFN - Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Zaffaroni, Alberto [Dipartimento di Fisica, Università di Milano-Bicocca,and INFN - Sezione di Milano-Bicocca, I-20126 Milano (Italy)
2016-06-28
We derive the four-dimensional low-energy effective field theory governing the moduli space of strongly coupled superconformal quiver gauge theories associated with D3-branes at Calabi-Yau conical singularities in the holographic regime of validity. We use the dual supergravity description provided by warped resolved conical geometries with mobile D3-branes. Information on the baryonic directions of the moduli space is also obtained by using wrapped Euclidean D3-branes. We illustrate our general results by discussing in detail their application to the Klebanov-Witten model.
International Nuclear Information System (INIS)
Mack, G.; Kalkreuter, T.; Palma, G.; Speh, M.
1992-05-01
Effective field theories encode the predictions of a quantum field theory at low energy. The effective theory has a fairly low utraviolet cutoff. As a result, loop corrections are small, at least if the effective action contains a term which is quadratic in the fields, and physical predictions can be read straight from the effective Lagrangean. Methods will be discussed how to compute an effective low energy action from a given fundamental action, either analytically or numerically, or by a combination of both methods. Basically, the idea is to integrate out the high frequency components of fields. This requires the choice of a 'blockspin', i.e. the specification af a low frequency field as a function of the fundamental fields. These blockspins will be fields of the effective field theory. The blockspin need not be a field of the same type as one of the fundamental fields, and it may be composite. Special features of blockspin in nonabelian gauge theories will be discussed in some detail. In analytical work and in multigrid updating schemes one needs interpolation kernels A from coarse to fine grid in addition to the averaging kernels C which determines the blockspin. A neural net strategy for finding optimal kernels is presented. Numerical methods are applicable to obtain actions of effective theories on lattices of finite volume. The special case of a 'lattice' with a single site (the constraint effective potential) is of particular interest. In a higgs model, the effective action reduces in this case to the free energy, considered as a function of a gauge covariant magnetization. Its shape determines the phase structure of the theory. Its loop expansion with and without gauge fields can be used to determine finite size corrections to numerical data. (orig.)
Higgs Effective Field Theories
2016-01-01
The main focus of this meeting is to present new theoretical advancements related to effective field theories, evaluate the impact of initial results from the LHC Run2, and discuss proposals for data interpretation/presentation during Run2. A crucial role of the meeting is to bring together theorists from different backgrounds and with different viewpoints and to extend bridges towards the experimental community. To this end, we would like to achieve a good balance between senior and junior speakers, enhancing the visibility of younger scientists while keeping some overview talks.
Generalized chiral perturbation theory
International Nuclear Information System (INIS)
Knecht, M.; Stern, J.
1994-01-01
The Generalized Chiral Perturbation Theory enlarges the framework of the standard χPT (Chiral Perturbation Theory), relaxing certain assumptions which do not necessarily follow from QCD or from experiment, and which are crucial for the usual formulation of the low energy expansion. In this way, experimental tests of the foundations of the standard χPT become possible. Emphasis is put on physical aspects rather than on formal developments of GχPT. (author). 31 refs
Relativistic Chiral Kinetic Theory
International Nuclear Information System (INIS)
Stephanov, Mikhail
2016-01-01
This very brief review of the recent progress in chiral kinetic theory is based on the results of Refs. [J.-Y. Chen, D. T. Son, M. A. Stephanov, H.-U. Yee, Y. Yin, Lorentz Invariance in Chiral Kinetic Theory, Phys. Rev. Lett. 113 (18) (2014) 182302. doi: (10.1103/PhysRevLett.113.182302); J.-Y. Chen, D. T. Son, M. A. Stephanov, Collisions in Chiral Kinetic Theory, Phys. Rev. Lett. 115 (2) (2015) 021601. doi: (10.1103/PhysRevLett.115.021601); M. A. Stephanov, H.-U. Yee, The no-drag frame for anomalous chiral fluid, Phys. Rev. Lett. 116 (12) (2016) 122302. doi: (10.1103/PhysRevLett.116.122302)].
Relativistic Chiral Kinetic Theory
Energy Technology Data Exchange (ETDEWEB)
Stephanov, Mikhail
2016-12-15
This very brief review of the recent progress in chiral kinetic theory is based on the results of Refs. [J.-Y. Chen, D. T. Son, M. A. Stephanov, H.-U. Yee, Y. Yin, Lorentz Invariance in Chiral Kinetic Theory, Phys. Rev. Lett. 113 (18) (2014) 182302. doi: (10.1103/PhysRevLett.113.182302); J.-Y. Chen, D. T. Son, M. A. Stephanov, Collisions in Chiral Kinetic Theory, Phys. Rev. Lett. 115 (2) (2015) 021601. doi: (10.1103/PhysRevLett.115.021601); M. A. Stephanov, H.-U. Yee, The no-drag frame for anomalous chiral fluid, Phys. Rev. Lett. 116 (12) (2016) 122302. doi: (10.1103/PhysRevLett.116.122302)].
Effective field theory and the quark model
International Nuclear Information System (INIS)
Durand, Loyal; Ha, Phuoc; Jaczko, Gregory
2001-01-01
We analyze the connections between the quark model (QM) and the description of hadrons in the low-momentum limit of heavy-baryon effective field theory in QCD. By using a three-flavor-index representation for the effective baryon fields, we show that the 'nonrelativistic' constituent QM for baryon masses and moments is completely equivalent through O(m s ) to a parametrization of the relativistic field theory in a general spin-flavor basis. The flavor and spin variables can be identified with those of effective valence quarks. Conversely, the spin-flavor description clarifies the structure and dynamical interpretation of the chiral expansion in effective field theory, and provides a direct connection between the field theory and the semirelativistic models for hadrons used in successful dynamical calculations. This allows dynamical information to be incorporated directly into the chiral expansion. We find, for example, that the striking success of the additive QM for baryon magnetic moments is a consequence of the relative smallness of the non-additive spin-dependent corrections
Nuclear forces and chiral theories
International Nuclear Information System (INIS)
Friar, J.L.; Washington Univ., Seattle, WA
1995-01-01
Recent successes in ab initio calculations of light nuclei (A=2-6) will be reviewed and correlated with the dynamical consequences of chiral symmetry. The tractability of nuclear physics evinced by these results is evidence for that symmetry. The relative importance of three-nucleon forces, four-nucleon forces, multi-pion exchanges, and relativistic corrections will be discussed in the context of effective field theories and dimensional power counting. Isospin violation in the nuclear force will also be discussed in this context
Chiral algebras for trinion theories
International Nuclear Information System (INIS)
Lemos, Madalena; Peelaers, Wolfger
2015-01-01
It was recently understood that one can identify a chiral algebra in any four-dimensional N=2 superconformal theory. In this note, we conjecture the full set of generators of the chiral algebras associated with the T n theories. The conjecture is motivated by making manifest the critical affine module structure in the graded partition function of the chiral algebras, which is computed by the Schur limit of the superconformal index for T n theories. We also explicitly construct the chiral algebra arising from the T 4 theory. Its null relations give rise to new T 4 Higgs branch chiral ring relations.
Nucleon Polarisabilities and Effective Field Theories
Griesshammer, Harald W.
2017-09-01
Low-energy Compton scattering probes the nucleon's two-photon response to electric and magnetic fields at fixed photon frequency and multipolarity. It tests the symmetries and strengths of the interactions between constituents, and with photons. For convenience, this energy-dependent information is often compressed into the two scalar dipole polarisabilities αE 1 and βM 1 at zero photon energy. These are fundamental quantities, and important for the proton charge radius puzzle and the Lamb shift of muonic hydrogen. Combined with emerging lattice QCD computations, they provide stringent tests for our understanding of hadron structure. Extractions of the proton and neutron polarisabilities from all published elastic data below 300 MeV in Chiral Effective Field Theory with explicit Δ (1232) are now available. This talk emphasises χEFT as natural bridge between lattice QCD and ongoing or approved efforts at HI γS, MAMI and MAX-lab. Chiral lattice extrapolations from mπ > 200 MeV to the physical point compare well to lattice computations. Combining χEFT with high-intensity experiments with polarised targets and polarised beams will extract not only scalar polarisabilities, but in particular the four so-far poorly explored spin-polarisabilities. These parametrise the stiffness of the spin in external electro-magnetic fields (nucleonic bi-refringence/Faraday effect). New chiral predictions for proton, deuteron and 3He observables show intriguing sensitivities on spin and neutron polarisabilities. Data consistency and a model-independent quantification of residual theory uncertainties by Bayesian analysis are also discussed. Proton-neutron differences explore the interplay between chiral symmetry breaking and short-distance Physics. Finally, I address their impact on the neutron-proton mass difference, big-bang nucleosynthesis, and their relevance for anthropic arguments. Supported in part by DOE DE-SC0015393 and George Washington University.
Effective field theory dimensional regularization
International Nuclear Information System (INIS)
Lehmann, Dirk; Prezeau, Gary
2002-01-01
A Lorentz-covariant regularization scheme for effective field theories with an arbitrary number of propagating heavy and light particles is given. This regularization scheme leaves the low-energy analytic structure of Greens functions intact and preserves all the symmetries of the underlying Lagrangian. The power divergences of regularized loop integrals are controlled by the low-energy kinematic variables. Simple diagrammatic rules are derived for the regularization of arbitrary one-loop graphs and the generalization to higher loops is discussed
Effective field theory dimensional regularization
Lehmann, Dirk; Prézeau, Gary
2002-01-01
A Lorentz-covariant regularization scheme for effective field theories with an arbitrary number of propagating heavy and light particles is given. This regularization scheme leaves the low-energy analytic structure of Greens functions intact and preserves all the symmetries of the underlying Lagrangian. The power divergences of regularized loop integrals are controlled by the low-energy kinematic variables. Simple diagrammatic rules are derived for the regularization of arbitrary one-loop graphs and the generalization to higher loops is discussed.
Higgs effective field theories. Systematics and applications
Energy Technology Data Exchange (ETDEWEB)
Krause, Claudius G.
2016-07-28
Researchers of the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) announced on July 4th, 2012, the observation of a new particle. The properties of the particle agree, within the relatively large experimental uncertainties, with the properties of the long-sought Higgs boson. Particle physicists around the globe are now wondering, ''Is it the Standard Model Higgs that we observe; or is it another particle with similar properties?'' We employ effective field theories (EFTs) for a general, model-independent description of the particle. We use a few, minimal assumptions - Standard Model (SM) particle content and a separation of scales to the new physics - which are supported by current experimental results. By construction, effective field theories describe a physical system only at a certain energy scale, in our case at the electroweak-scale v. Effects of new physics from a higher energy-scale, Λ, are described by modified interactions of the light particles. In this thesis, ''Higgs Effective Field Theories - Systematics and Applications'', we discuss effective field theories for the Higgs particle, which is not necessarily the Higgs of the Standard Model. In particular, we focus on a systematic and consistent expansion of the EFT. The systematics depends on the dynamics of the new physics. We distinguish two different consistent expansions. EFTs that describe decoupling new-physics effects and EFTs that describe non-decoupling new-physics effects. We briefly discuss the first case, the SM-EFT. The focus of this thesis, however, is on the non-decoupling EFTs. We argue that the loop expansion is the consistent expansion in the second case. We introduce the concept of chiral dimensions, equivalent to the loop expansion. Using the chiral dimensions, we expand the electroweak chiral Lagrangian up to next-to-leading order, O(f{sup 2}/Λ{sup 2})=O(1/16π{sup 2}). Further, we discuss how different
Lattice regularized chiral perturbation theory
International Nuclear Information System (INIS)
Borasoy, Bugra; Lewis, Randy; Ouimet, Pierre-Philippe A.
2004-01-01
Chiral perturbation theory can be defined and regularized on a spacetime lattice. A few motivations are discussed here, and an explicit lattice Lagrangian is reviewed. A particular aspect of the connection between lattice chiral perturbation theory and lattice QCD is explored through a study of the Wess-Zumino-Witten term
Nuclear Forces from Effective Field Theory
International Nuclear Information System (INIS)
Krebs, H.
2011-01-01
Chiral effective field theory allows for a systematic and model-independent derivation of the forces between nucleons in harmony with the symmetries of the quantum chromodynamics. After a brief review on the current status in the development of the chiral nuclear forces I will focus on the role of the Δ-resonance contributions in the nuclear dynamics.We find improvement in the convergence of the chiral expansion of the nuclear forces if we explicitly take into account the Δ-resonance degrees of freedom. The overall results for two-nucleon forces with and without explicit Δ-resonance degrees of freedom are remarkably similar. We discussed the long- and shorter-range N 3 LO contributions to chiral three-nucleon forces. No additional free parameters appear at this order. There are five different topology classes which contribute to the forces. Three of them describe long-range contributions which constitute the first systematic corrections to the leading 2π exchange that appear at N 2 LO. Another two contributions are of a shorter range and include, additionally to an exchange of pions, also one short-range contact interaction and all corresponding 1/m corrections. The requirement of renormalizability leads to unique expressions for N 3 LO contributions to the three-nucleon force (except for 1/m-corrections). We presented the complete N 2 LO analysis of the nuclear forces with explicit Δ-isobar degrees of freedom. Although the overall results in the isospin-conserving case are very similar in the Δ-less and Δ-full theories, we found a much better convergence in all peripheral partial waves once Δ-resonance is explicitly taken into account. The leading CSB contributions to nuclear forces are proportional to nucleon- and Δ-mass splittings. There appear strong cancellations between the two contributions which at leading order yield weaker V III potentials. This effect is, however, entirely compensated at subleading order such that the results in the theories
Renormalons in effective field theories
International Nuclear Information System (INIS)
Luke, M.; Manohar, A.V.; Savage, M.J.
1995-01-01
We investigate the high-order behavior of perturbative matching conditions in effective field theories. These series are typically badly divergent, and are not Borel summable due to infrared and ultraviolet renormalons which introduce ambiguities in defining the sum of the series. We argue that, when treated consistently, there is no physical significance to these ambiguities. Although nonperturbative matrix elements and matching conditions are in general ambiguous, the ambiguity in any physical observable is always higher order in 1/M than the theory has been defined. We discuss the implications for the recently noticed infrared renormalon in the pole mass of a heavy quark. We show that a ratio of form factors in exclusive Λ b decays (which is related to the pole mass) is free from renormalon ambiguities regardless of the mass used as the expansion parameter of heavy quark effective theory. The renormalon ambiguities also cancel in inclusive heavy hadron decays. Finally, we demonstrate the cancellation of renormalons in a four-Fermi effective theory obtained by integrating out a heavy colored scalar
Analysis of General Power Counting Rules in Effective Field Theory
Gavela, B M; Manohar, A V; Merlo, L
2016-01-01
We derive the general counting rules for a quantum effective field theory (EFT) in $\\mathsf{d}$ dimensions. The rules are valid for strongly and weakly coupled theories, and predict that all kinetic energy terms are canonically normalized. They determine the energy dependence of scattering cross sections in the range of validity of the EFT expansion. The size of cross sections is controlled by the $\\Lambda$ power counting of EFT, not by chiral counting, even for chiral perturbation theory ($\\chi$PT). The relation between $\\Lambda$ and $f$ is generalized to $\\mathsf{d}$ dimensions. We show that the naive dimensional analysis $4\\pi$ counting is related to $\\hbar$ counting. The EFT counting rules are applied to $\\chi$PT, to Standard Model EFT and to the non-trivial case of Higgs EFT, which combines the $\\Lambda$ and chiral counting rules within a single theory.
Review of chiral perturbation theory
Indian Academy of Sciences (India)
Abstract. A review of chiral perturbation theory and recent developments on the comparison of its predictions with experiment is presented. Some interesting topics with scope for further elaboration are touched upon.
A primer for Chiral Perturbative Theory
International Nuclear Information System (INIS)
Scherer, Stefan; Schindler, Matthias R.; George Washington Univ., Washington, DC
2012-01-01
Chiral Perturbation Theory, as effective field theory, is a commonly accepted and well established working tool, approximating quantum chromodynamics at energies well below typical hadron masses. This volume, based on a number of lectures and supplemented with additional material, provides a pedagogical introduction for graduate students and newcomers entering the field from related areas of nuclear and particle physics. Starting with the the Lagrangian of the strong interactions and general symmetry principles, the basic concepts of Chiral Perturbation Theory in the mesonic and baryonic sectors are developed. The application of these concepts is then illustrated with a number of examples. A large number of exercises (81, with complete solutions) are included to familiarize the reader with helpful calculational techniques. (orig.)
A primer for chiral perturbation theory
Scherer, Stefan
2012-01-01
Chiral Perturbation Theory, as effective field theory, is a commonly accepted and well established working tool, approximating quantum chromodynamics at energies well below typical hadron masses. This volume, based on a number of lectures and supplemented with additional material, provides a pedagogical introduction for graduate students and newcomers entering the field from related areas of nuclear and particle physics. Starting with the the Lagrangian of the strong interactions and general symmetry principles, the basic concepts of Chiral Perturbation Theory in the mesonic and baryonic sectors are developed. The application of these concepts is then illustrated with a number of examples. A large number of exercises (81, with complete solutions) are included to familiarize the reader with helpful calculational techniques.
Effective Field Theory on Manifolds with Boundary
Albert, Benjamin I.
In the monograph Renormalization and Effective Field Theory, Costello made two major advances in rigorous quantum field theory. Firstly, he gave an inductive position space renormalization procedure for constructing an effective field theory that is based on heat kernel regularization of the propagator. Secondly, he gave a rigorous formulation of quantum gauge theory within effective field theory that makes use of the BV formalism. In this work, we extend Costello's renormalization procedure to a class of manifolds with boundary and make preliminary steps towards extending his formulation of gauge theory to manifolds with boundary. In addition, we reorganize the presentation of the preexisting material, filling in details and strengthening the results.
Chiral perturbation theory with nucleons
International Nuclear Information System (INIS)
Meissner, U.G.
1991-09-01
I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external moments and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward-identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures of consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the methods. Some processes which are discussed are threshold photopion production, low-energy compton scattering off nucleons, πN scattering and the σ-term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon
Issues of effective field theories with resonances
International Nuclear Information System (INIS)
Gegelia, J.; Japaridze, G.
2014-01-01
We address some issues of renormalization and symmetries of effective field theories with unstable particles - resonances. We also calculate anomalous contributions in the divergence of the singlet axial current in an effective field theory of massive SU(N) Yang-Mills fields interacting with fermions and discuss their possible relevance to the strong CP problem. (author)
Status of chiral perturbation theory
International Nuclear Information System (INIS)
Ecker, G.
1996-10-01
A survey is made of semileptonic and nonleptonic kaon decays in the framework of chiral perturbation theory. The emphasis is on what has been done rather than how it was done. The theoretical predictions are compared with available experimental results. (author)
Principles of chiral perturbation theory
International Nuclear Information System (INIS)
Leutwyler, H.
1995-01-01
An elementary discussion of the main concepts used in chiral perturbation theory is given in textbooks and a more detailed picture of the applications may be obtained from the reviews. Concerning the foundations of the method, the literature is comparatively scarce. So, I will concentrate on the basic concepts and explain why the method works. (author)
Effective field theory for NN interactions
International Nuclear Information System (INIS)
Tran Duy Khuong; Vo Hanh Phuc
2003-01-01
The effective field theory of NN interactions is formulated and the power counting appropriate to this case is reviewed. It is more subtle than in most effective field theories since in the limit that the S-wave NN scattering lengths go to infinity. It is governed by nontrivial fixed point. The leading two body terms in the effective field theory for nucleon self interactions are scale invariant and invariant under Wigner SU(4) spin-isospin symmetry in this limit. Higher body terms with no derivatives (i.e. three and four body terms) are automatically invariant under Wigner symmetry. (author)
Effective field theory approaches for tensor potentials
Energy Technology Data Exchange (ETDEWEB)
Jansen, Maximilian
2016-11-14
Effective field theories are a widely used tool to study physical systems at low energies. We apply them to systematically analyze two and three particles interacting via tensor potentials. Two examples are addressed: pion interactions for anti D{sup 0}D{sup *0} scattering to dynamically generate the X(3872) and dipole interactions for two and three bosons at low energies. For the former, the one-pion exchange and for the latter, the long-range dipole force induce a tensor-like structure of the potential. We apply perturbative as well as non-perturbative methods to determine low-energy observables. The X(3872) is of major interest in modern high-energy physics. Its exotic characteristics require approaches outside the range of the quark model for baryons and mesons. Effective field theories represent such methods and provide access to its peculiar nature. We interpret the X(3872) as a hadronic molecule consisting of neutral D and D{sup *} mesons. It is possible to apply an effective field theory with perturbative pions. Within this framework, we address chiral as well as finite volume extrapolations for low-energy observables, such as the binding energy and the scattering length. We show that the two-point correlation function for the D{sup *0} meson has to be resummed to cure infrared divergences. Moreover, next-to-leading order coupling constants, which were introduced by power counting arguments, appear to be essential to renormalize the scattering amplitude. The binding energy as well as the scattering length display a moderate dependence on the light quark masses. The X(3872) is most likely deeper bound for large light quark masses. In a finite volume on the other hand, the binding energy significantly increases. The dependence on the light quark masses and the volume size can be simultaneously obtained. For bosonic dipoles we apply a non-perturbative, numerical approach. We solve the Lippmann-Schwinger equation for the two-dipole system and the Faddeev
Staggered chiral random matrix theory
International Nuclear Information System (INIS)
Osborn, James C.
2011-01-01
We present a random matrix theory for the staggered lattice QCD Dirac operator. The staggered random matrix theory is equivalent to the zero-momentum limit of the staggered chiral Lagrangian and includes all taste breaking terms at their leading order. This is an extension of previous work which only included some of the taste breaking terms. We will also present some results for the taste breaking contributions to the partition function and the Dirac eigenvalues.
QCD Effective Field Theories for Heavy Quarkonium
International Nuclear Information System (INIS)
Brambilla, Nora
2006-01-01
QCD nonrelativistic effective field theories (NREFT) are the modern and most suitable frame to describe heavy quarkonium properties. Here I summarize few relevant concepts and some of the interesting physical applications (spectrum, decays, production) of NREFT
What's wrong with anomalous chiral gauge theory?
International Nuclear Information System (INIS)
Kieu, T.D.
1994-05-01
It is argued on general ground and demonstrated in the particular example of the Chiral Schwinger Model that there is nothing wrong with apparently anomalous chiral gauge theory. If quantised correctly, there should be no gauge anomaly and chiral gauge theory should be renormalisable and unitary, even in higher dimensions and with non-Abelian gauge groups. Furthermore, it is claimed that mass terms for gauge bosons and chiral fermions can be generated without spoiling the gauge invariance. 19 refs
Quenched Chiral Perturbation Theory to one loop
Colangelo, G.; Pallante, E.
The divergences of the generating functional of quenched Chiral Perturbation theory (qCHPT) to one loop are computed in closed form. We show how the quenched chiral logarithms can be reabsorbed in the renormalization of the B0 parameter of the leading order Lagrangian. Finally, we do the chiral
Effective field theory for triaxially deformed nuclei
Energy Technology Data Exchange (ETDEWEB)
Chen, Q.B. [Technische Universitaet Muechen, Physik-Department, Garching (Germany); Peking University, State Key Laboratory of Nuclear Physics and Technology, School of Physics, Beijing (China); Kaiser, N. [Technische Universitaet Muechen, Physik-Department, Garching (Germany); Meissner, Ulf G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Institute for Advanced Simulation, Institut fuer Kernphysik, Juelich Center for Hadron Physics and JARA-HPC, Forschungszentrum Juelich, Juelich (Germany); Meng, J. [Peking University, State Key Laboratory of Nuclear Physics and Technology, School of Physics, Beijing (China); Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); University of Stellenbosch, Department of Physics, Stellenbosch (South Africa)
2017-10-15
Effective field theory is generalized to investigate the rotational motion of triaxially deformed even-even nuclei. The Hamiltonian for the triaxial rotor is obtained up to next-to-leading order within the effective field theory formalism. Its applicability is examined by comparing with a five-dimensional rotor-vibrator Hamiltonian for the description of the energy spectra of the ground state and γ band in Ru isotopes. It is found that by taking into account the next-to-leading order corrections, the ground state band in the whole spin region and the γ band in the low spin region are well described. The deviations for high-spin states in the γ bands point towards the importance of including vibrational degrees of freedom in the effective field theory formulation. (orig.)
Effective field theory approach to nuclear matter
International Nuclear Information System (INIS)
Saviankou, P.; Gruemmer, F.; Epelbaum, E.; Krewald, S.; Meissner, Ulf-G.
2006-01-01
Effective field theory provides a systematic approach to hardon physics and few-nucleon systems. It allows one to determine the effective two-, three-, and more-nucleon interactions which are consistent with each other. We present a project to derive bulk properties of nuclei from the effective nucleonic interactions
Playing with QCD I: effective field theories
International Nuclear Information System (INIS)
Fraga, Eduardo S.
2009-01-01
The building blocks of hadrons are quarks and gluons, although color is confined into singlet states. QCD is believed to be the fundamental theory of strong interactions. Its asymptotically free nature puts the vacuum out of reach for perturbation theory. The Lagrangian of QCD and the Feynman rules associated were built by using the Gauge Principle, starting from the quark matter fields and obtaining gluons as connections. A simpler, and sometimes necessary or complementary, approach is provided by effective field theories or effective models, especially when one has to deal with the nonperturbative sector of the theory. (author)
Effective field theory for magnetic compactifications
Energy Technology Data Exchange (ETDEWEB)
Buchmuller, Wilfried; Dierigl, Markus [Deutsches Elektronen-Synchrotron DESY,22607 Hamburg (Germany); Dudas, Emilian [Centre de Physique Théorique, École Polytechnique, CNRS, Université Paris-Saclay,F-91128 Palaiseau (France); Schweizer, Julian [Deutsches Elektronen-Synchrotron DESY,22607 Hamburg (Germany)
2017-04-10
Magnetic flux plays an important role in compactifications of field and string theories in two ways, it generates a multiplicity of chiral fermion zero modes and it can break supersymmetry. We derive the complete four-dimensional effective action for N=1 supersymmetric Abelian and non-Abelian gauge theories in six dimensions compactified on a torus with flux. The effective action contains the tower of charged states and it accounts for the mass spectrum of bosonic and fermionic fields as well as their level-dependent interactions. This allows us to compute quantum corrections to the mass and couplings of Wilson lines. We find that the one-loop corrections vanish, contrary to the case without flux. This can be traced back to the spontaneous breaking of symmetries of the six-dimensional theory by the background gauge field, with the Wilson lines as Goldstone bosons.
Status of effective field theory of NN scattering
International Nuclear Information System (INIS)
Beane, S.R.
1998-06-01
There exist many nucleon-nucleon potentials which reproduce phase shifts and nuclear properties with remarkable accuracy. Three fundamental features are shared by these potential models: (1) pions are important at long distances, (2) there is a source of intermediate-range attraction, and (3) there is a source of short-distance repulsion. However, in general, distinct physical mechanisms in these models account for the same feature of the nuclear force. Agreement with experiment is maintained in spite of these differences because of the large number of fit parameters. Systematic approaches to the scattering of strongly interacting particles, such as chiral perturbation theory, are based on the ideas of effective field theory (EFT). The author reviews recent progress in developing a systematic power counting scheme for scattering processes involving more than one nucleon
Effective-field theories for heavy quarkonium
International Nuclear Information System (INIS)
Brambilla, Nora; Pineda, Antonio; Soto, Joan; Vairo, Antonio
2005-01-01
This article reviews recent theoretical developments in heavy-quarkonium physics from the point of view of effective-field theories of QCD. We discuss nonrelativistic QCD and concentrate on potential nonrelativistic QCD. The main goal will be to derive Schroedinger equations based on QCD that govern heavy-quarkonium physics in the weak- and strong-coupling regimes. Finally, the review discusses a selected set of applications, which include spectroscopy, inclusive decays, and electromagnetic threshold production
Consistency relations in effective field theory
Energy Technology Data Exchange (ETDEWEB)
Munshi, Dipak; Regan, Donough, E-mail: D.Munshi@sussex.ac.uk, E-mail: D.Regan@sussex.ac.uk [Astronomy Centre, School of Mathematical and Physical Sciences, University of Sussex, Brighton BN1 9QH (United Kingdom)
2017-06-01
The consistency relations in large scale structure relate the lower-order correlation functions with their higher-order counterparts. They are direct outcome of the underlying symmetries of a dynamical system and can be tested using data from future surveys such as Euclid. Using techniques from standard perturbation theory (SPT), previous studies of consistency relation have concentrated on continuity-momentum (Euler)-Poisson system of an ideal fluid. We investigate the consistency relations in effective field theory (EFT) which adjusts the SPT predictions to account for the departure from the ideal fluid description on small scales. We provide detailed results for the 3D density contrast δ as well as the scaled divergence of velocity θ-bar . Assuming a ΛCDM background cosmology, we find the correction to SPT results becomes important at k ∼> 0.05 h/Mpc and that the suppression from EFT to SPT results that scales as square of the wave number k , can reach 40% of the total at k ≈ 0.25 h/Mpc at z = 0. We have also investigated whether effective field theory corrections to models of primordial non-Gaussianity can alter the squeezed limit behaviour, finding the results to be rather insensitive to these counterterms. In addition, we present the EFT corrections to the squeezed limit of the bispectrum in redshift space which may be of interest for tests of theories of modified gravity.
On the derivation of effective field theories
International Nuclear Information System (INIS)
Uzunov, Dimo I.
2004-12-01
A general self-consistency approach allows a thorough treatment of the corrections to the standard mean-field approximation (MFA). The natural extension of standard MFA with the help of cumulant expansion leads to a new point of view on the effective field theories. The proposed approach can be used for a systematic treatment of fluctuation effects of various length scales and, perhaps, for the development of a new coarse graining procedure. We outline and justify our method by some preliminary calculations. Concrete results are given for the critical temperature and the Landau parameters of the φ 4 -theory - the field counterpart of the Ising model. An important unresolved problem of the modern theory of phase transitions - the problem for the calculation of the true critical temperature, is considered within the framework of the present approach. A comprehensive description of the ground state properties of many-body systems is also demonstrated. (author)
A periodic table of effective field theories
Energy Technology Data Exchange (ETDEWEB)
Cheung, Clifford [Walter Burke Institute for Theoretical Physics,California Institute of Technology,Pasadena, CA (United States); Kampf, Karol; Novotny, Jiri [Institute of Particle and Nuclear Physics,Faculty of Mathematics and Physics, Charles University,Prague (Czech Republic); Shen, Chia-Hsien [Walter Burke Institute for Theoretical Physics,California Institute of Technology,Pasadena, CA (United States); Trnka, Jaroslav [Center for Quantum Mathematics and Physics (QMAP),Department of Physics, University of California,Davis, CA (United States)
2017-02-06
We systematically explore the space of scalar effective field theories (EFTs) consistent with a Lorentz invariant and local S-matrix. To do so we define an EFT classification based on four parameters characterizing 1) the number of derivatives per interaction, 2) the soft properties of amplitudes, 3) the leading valency of the interactions, and 4) the spacetime dimension. Carving out the allowed space of EFTs, we prove that exceptional EFTs like the non-linear sigma model, Dirac-Born-Infeld theory, and the special Galileon lie precisely on the boundary of allowed theory space. Using on-shell momentum shifts and recursion relations, we prove that EFTs with arbitrarily soft behavior are forbidden and EFTs with leading valency much greater than the spacetime dimension cannot have enhanced soft behavior. We then enumerate all single scalar EFTs in d<6 and verify that they correspond to known theories in the literature. Our results suggest that the exceptional theories are the natural EFT analogs of gauge theory and gravity because they are one-parameter theories whose interactions are strictly dictated by properties of the S-matrix.
Massive states in chiral perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Mallik, S [Saha Inst. of Nuclear Physics, Calcutta (India)
1995-08-01
It is shown that the chiral nonanalytic terms generated by {Delta}{sub 33} resonance in the nucleon self-energy is reproduced in chiral perturbation theory by perturbing appropriate local operators contained in the pion-nucleon effective Lagrangian itself. (orig.)
Nucleon parton distributions in chiral perturbation theory
International Nuclear Information System (INIS)
Moiseeva, Alena
2013-01-01
Properties of the chiral expansion of nucleon light-cone operators have been studied. In the framework of the chiral perturbation theory we have demonstrated that convergency of the chiral expansion of nucleon parton distributions strongly depends on the value of the variable x. Three regions in x with essentially different analytical properties of the resulting chiral expansion for parton distributions were found. For each of the regions we have elaborated special power counting rules corresponding to the partial resummation of the chiral series. The nonlocal effective operators for the vector and the axial nucleon parton distributions have been constructed at the zeroth and the first chiral order. Using the derived nonlocal operators and the derived power counting rules we have obtained the second order expressions for the nucleon GPDs H(x,ξ,Δ 2 ), H(x,ξ,Δ 2 ),E(x,ξ,Δ 2 ) valid in the region x>or similar a 2 χ .
Three-loop corrections in a covariant effective field theory
International Nuclear Information System (INIS)
McIntire, Jeff
2008-01-01
Chiral effective field theories have been used with success in the study of nuclear structure. It is of interest to systematically improve these energy functionals (particularly that of quantum hadrodynamics) through the inclusion of many-body correlations. One possible source of improvement is the loop expansion. Using the techniques of Infrared Regularization, the short-range, local dynamics at each order in the loops is absorbed into the parameterization of the underlying effective Lagrangian. The remaining nonlocal, exchange correlations must be calculated explicitly. Given that the interactions of quantum hadrodynamics are relatively soft, the loop expansion may be manageable or even perturbative in nuclear matter. This work investigates the role played by the three-loop contributions to the loop expansion for quantum hadrodynamics
The Effective Field Theory of nonsingular cosmology
Energy Technology Data Exchange (ETDEWEB)
Cai, Yong [School of Physics, University of Chinese Academy of Sciences,Beijing 100049 (China); Wan, Youping [School of Physics, University of Chinese Academy of Sciences,Beijing 100049 (China); CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy,University of Science and Technology of China, Chinese Academy of Sciences,Hefei, Anhui 230026 (China); Li, Hai-Guang [School of Physics, University of Chinese Academy of Sciences,Beijing 100049 (China); Qiu, Taotao [Institute of Astrophysics, Central China Normal University,Wuhan 430079 (China); Key Laboratory of Quark and Lepton Physics (MOE), Central China Normal University,Wuhan 430079 (China); Piao, Yun-Song [School of Physics, University of Chinese Academy of Sciences,Beijing 100049 (China); Institute of Theoretical Physics, Chinese Academy of Sciences,P.O. Box 2735, Beijing 100190 (China)
2017-01-20
In this paper, we explore the nonsingular cosmology within the framework of the Effective Field Theory (EFT) of cosmological perturbations. Due to the recently proved no-go theorem, any nonsingular cosmological models based on the cubic Galileon suffer from pathologies. We show how the EFT could help us clarify the origin of the no-go theorem, and offer us solutions to break the no-go. Particularly, we point out that the gradient instability can be removed by using some spatial derivative operators in EFT. Based on the EFT description, we obtain a realistic healthy nonsingular cosmological model, and show the perturbation spectrum can be consistent with the observations.
The Effective Field Theory of nonsingular cosmology
International Nuclear Information System (INIS)
Cai, Yong; Wan, Youping; Li, Hai-Guang; Qiu, Taotao; Piao, Yun-Song
2017-01-01
In this paper, we explore the nonsingular cosmology within the framework of the Effective Field Theory (EFT) of cosmological perturbations. Due to the recently proved no-go theorem, any nonsingular cosmological models based on the cubic Galileon suffer from pathologies. We show how the EFT could help us clarify the origin of the no-go theorem, and offer us solutions to break the no-go. Particularly, we point out that the gradient instability can be removed by using some spatial derivative operators in EFT. Based on the EFT description, we obtain a realistic healthy nonsingular cosmological model, and show the perturbation spectrum can be consistent with the observations.
Effective Field Theory with Two Higgs Doublets
Crivellin, Andreas; Procura, Massimiliano
2016-01-01
In this article we extend the effective field theory framework describing new physics effects to the case where the underlying low-energy theory is a Two-Higgs-Doublet model. We derive a complete set of independent operators up to dimension six assuming a $Z_2$-invariant CP-conserving Higgs potential. The effects on Higgs and gauge boson masses, mixing angles in the Higgs sector as well as couplings to fermions and gauge bosons are computed. At variance with the case of a single Higgs doublet, we find that pair production of SM-like Higgses, arising through dimension-six operators, is not fixed by fermion-fermion-Higgs couplings and can therefore be sizable.
Chiral unitary theory: Application to nuclear problems
Indian Academy of Sciences (India)
Chiral unitary theory: Application to nuclear problems ... Physics Department, Nara Women University, Nara, Japan. 5 ... RCNP, Osaka University, Osaka, Japan ...... We acknowledge partial financial support from the DGICYT under contract ...
Supersymmetric chiral electrodynamics as a renormalized theory
International Nuclear Information System (INIS)
Ansel'm, A.A.; Iogansen, A.A.
1991-01-01
It is well know that the QED of chiral fermions is a nonrenormalizable theory, inasmuch as the gauge current in it is not conserved because of the presence of an anomaly. It is evident that in this theory unitarity is also violated. The principal object of investigation in the present paper is supersymmetric chiral QED, supersymmetric QED is a renormalizable theory. This happens because the radiative corrections generate here a charged current of a chiral fermion that appears in the chiral (i.e., longitudinal) part of the vector supermultiplet. At first sight, the chiral part of the vector multiplet is unphysical and contains only supergauge degrees of freedom. However, this is valid only at the classical level, whereas, because of the anomaly, the radiative corrections lead to nonconservation of the gauge current, as a result of which the degrees of freedom associated with the chiral part of the vector multiplet become physical. On the other hand, owing to the nonconservation of the gauge charge, the apparently neutral fermion appearing int he chiral (longitudinal) part of the vector superfield becomes charged
Effective field theory analysis of Higgs naturalness
Energy Technology Data Exchange (ETDEWEB)
Bar-Shalom, Shaouly [Technion-Israel Inst. of Tech., Haifa (Israel); Soni, Amarjit [Brookhaven National Lab. (BNL), Upton, NY (United States); Wudka, Jose [Univ. of California, Riverside, CA (United States)
2015-07-20
Assuming the presence of physics beyond the Standard Model ( SM) with a characteristic scale M ~ O (10) TeV, we investigate the naturalness of the Higgs sector at scales below M using an effective field theory (EFT) approach. We obtain the leading 1 -loop EFT contributions to the Higgs mass with a Wilsonian-like hard cutoff, and determine t he constraints on the corresponding operator coefficients for these effects to alleviate the little hierarchy problem up to the scale of the effective action Λ < M , a condition we denote by “EFT-naturalness”. We also determine the types of physics that can lead to EFT-naturalness and show that these types of new physics are best probed in vector-boson and multiple-Higgs production. The current experimental constraints on these coefficients are also discussed.
Effective field theory for cold atoms
International Nuclear Information System (INIS)
Hammer, H.-W.
2005-01-01
Effective Field Theory (EFT) provides a powerful framework that exploits a separation of scales in physical systems to perform systematically improvable, model-independent calculations. Particularly interesting are few-body systems with short-range interactions and large two-body scattering length. Such systems display remarkable universal features. In systems with more than two particles, a three-body force with limit cycle behavior is required for consistent renormalization already at leading order. We will review this EFT and some of its applications in the physics of cold atoms. Recent extensions of this approach to the four-body system and N-boson droplets in two spatial dimensions will also be discussed
Nuclear parity violation in effective field theory
International Nuclear Information System (INIS)
Zhu Shilin; Maekawa, C.M.; Holstein, B.R.; Ramsey-Musolf, M.J.; Kolck, U. van
2005-01-01
We reformulate the analysis of nuclear parity violation (PV) within the framework of effective field theory (EFT). To O(Q), the PV nucleon-nucleon (NN) interaction depends on five a priori unknown constants that parameterize the leading-order, short-range four-nucleon operators. When pions are included as explicit degrees of freedom, the potential contains additional medium- and long-range components parameterized by PV πNN coupling. We derive the form of the corresponding one- and two-pion-exchange potentials. We apply these considerations to a set of existing and prospective PV few-body measurements that may be used to determine the five independent low-energy constants relevant to the pionless EFT and the additional constants associated with dynamical pions. We also discuss the relationship between the conventional meson-exchange framework and the EFT formulation, and argue that the latter provides a more general and systematic basis for analyzing nuclear PV
Effective field theory of cosmological perturbations
International Nuclear Information System (INIS)
Piazza, Federico; Vernizzi, Filippo
2013-01-01
The effective field theory of cosmological perturbations stems from considering a cosmological background solution as a state displaying spontaneous breaking of time translations and (adiabatic) perturbations as the related Nambu–Goldstone modes. With this insight, one can systematically develop a theory for the cosmological perturbations during inflation and, with minor modifications, also describe in full generality the gravitational interactions of dark energy, which are relevant for late-time cosmology. The formalism displays a unique set of Lagrangian operators containing an increasing number of cosmological perturbations and derivatives. We give an introductory description of the unitary gauge formalism for theories with broken gauge symmetry—that allows us to write down the most general Lagrangian—and of the Stückelberg ‘trick’—that allows to recover gauge invariance and to make the scalar field explicit. We show how to apply this formalism to gravity and cosmology and we reproduce the detailed analysis of the action in the ADM variables. We also review some basic applications to inflation and dark energy. (paper)
Effective field theory of cosmological perturbations
Piazza, Federico; Vernizzi, Filippo
2013-11-01
The effective field theory of cosmological perturbations stems from considering a cosmological background solution as a state displaying spontaneous breaking of time translations and (adiabatic) perturbations as the related Nambu-Goldstone modes. With this insight, one can systematically develop a theory for the cosmological perturbations during inflation and, with minor modifications, also describe in full generality the gravitational interactions of dark energy, which are relevant for late-time cosmology. The formalism displays a unique set of Lagrangian operators containing an increasing number of cosmological perturbations and derivatives. We give an introductory description of the unitary gauge formalism for theories with broken gauge symmetry—that allows us to write down the most general Lagrangian—and of the Stückelberg ‘trick’—that allows to recover gauge invariance and to make the scalar field explicit. We show how to apply this formalism to gravity and cosmology and we reproduce the detailed analysis of the action in the ADM variables. We also review some basic applications to inflation and dark energy.
String creation, D-branes and effective field theory
International Nuclear Information System (INIS)
Hung Lingyan
2008-01-01
This paper addresses several unsettled issues associated with string creation in systems of orthogonal Dp-D(8-p) branes. The interaction between the branes can be understood either from the closed string or open string picture. In the closed string picture it has been noted that the DBI action fails to capture an extra RR exchange between the branes. We demonstrate how this problem persists upon lifting to M-theory. These D-brane systems are analysed in the closed string picture by using gauge-fixed boundary states in a non-standard lightcone gauge, in which RR exchange can be analysed precisely. The missing piece in the DBI action also manifests itself in the open string picture as a mismatch between the Coleman-Weinberg potential obtained from the effective field theory and the corresponding open string calculation. We show that this difference can be reconciled by taking into account the superghosts in the (0+1) effective theory of the chiral fermion, that arises from gauge fixing the spontaneously broken world-line local supersymmetries
Hidden QCD in Chiral Gauge Theories
DEFF Research Database (Denmark)
Ryttov, Thomas; Sannino, Francesco
2005-01-01
The 't Hooft and Corrigan-Ramond limits of massless one-flavor QCD consider the two Weyl fermions to be respectively in the fundamental representation or the two index antisymmetric representation of the gauge group. We introduce a limit in which one of the two Weyl fermions is in the fundamental...... representation and the other in the two index antisymmetric representation of a generic SU(N) gauge group. This theory is chiral and to avoid gauge anomalies a more complicated chiral theory is needed. This is the generalized Georgi-Glashow model with one vector like fermion. We show that there is an interesting...... phase in which the considered chiral gauge theory, for any N, Higgses via a bilinear condensate: The gauge interactions break spontaneously to ordinary massless one-flavor SU(3) QCD. The additional elementary fermionic matter is uncharged under this SU(3) gauge theory. It is also seen that when...
Low-energy meson physics (chiral theory)
International Nuclear Information System (INIS)
Volkov, M.K.; Pervushin, V.N.
1976-01-01
A quantum chiral theory which allows to obtain low-energy expansions of various hadron processes without introducing arbitrary parameters into the theory with the exception of hadron masses and interaction constants is presented. A hypothesis about the dynamic symmetry of strong interactions is suggested. The interaction lagrangian is derived which satisfies conditions of the dynamic symmetry. Examples of the use of the quantum chiral theory for describing low-energy processes of meson interaction are given. It is noted that the results obtained reproduce the actual qualitative pattern of various physical processes and in most cases result in good quantitative agreement with experiments
The Supersymmetric Effective Field Theory of Inflation
Energy Technology Data Exchange (ETDEWEB)
Delacrétaz, Luca V.; Gorbenko, Victor [Stanford Institute for Theoretical Physics, Stanford University,Stanford, CA 94306 (United States); Senatore, Leonardo [Stanford Institute for Theoretical Physics, Stanford University,Stanford, CA 94306 (United States); Kavli Institute for Particle Astrophysics and Cosmology, Stanford University and SLAC,Menlo Park, CA 94025 (United States)
2017-03-10
We construct the Supersymmetric Effective Field Theory of Inflation, that is the most general theory of inflationary fluctuations when time-translations and supersymmetry are spontaneously broken. The non-linear realization of these invariances allows us to define a complete SUGRA multiplet containing the graviton, the gravitino, the Goldstone of time translations and the Goldstino, with no auxiliary fields. Going to a unitary gauge where only the graviton and the gravitino are present, we write the most general Lagrangian built out of the fluctuations of these fields, invariant under time-dependent spatial diffeomorphisms, but softly-breaking time diffeomorphisms and gauged SUSY. With a suitable Stückelberg transformation, we introduce the Goldstone boson of time translation and the Goldstino of SUSY. No additional dynamical light field is needed. In the high energy limit, larger than the inflationary Hubble scale for the Goldstino, these fields decouple from the graviton and the gravitino, greatly simplifying the analysis in this regime. We study the phenomenology of this Lagrangian. The Goldstino can have a non-relativistic dispersion relation. Gravitino and Goldstino affect the primordial curvature perturbations at loop level. The UV modes running in the loops generate three-point functions which are degenerate with the ones coming from operators already present in the absence of supersymmetry. Their size is potentially as large as corresponding to f{sub NL}{sup equil.,orthog.}∼1 or, for particular operators, even ≫1. The non-degenerate contribution from modes of order H is estimated to be very small.
Effective field theories for correlated electrons
International Nuclear Information System (INIS)
Wallington, J.P.
1999-10-01
In this thesis, techniques of functional integration are applied to the construction of effective field theories for models of strongly correlated electrons. This is accomplished by means of the Hubbard-Stratonovic transformation which maps a system of interacting fermions onto one of free fermions interacting, not with each other, but with bosonic fields representing the collective modes of the system. Different choices of transformation are investigated throughout the thesis. It is shown that there exists a new group of discrete symmetries and transformations of the Hubbard model. Using this new group, the problem of choosing a Hubbard-Stratonovic decomposition of the Hubbard interaction term is solved. In the context of the exotic doped barium bismuthates, an extended Hubbard model with on-site attraction and nearest neighbour repulsion is studied. Mean field and renormalisation group analyses show a 'pseudospin-flop' from charge density wave to superconductivity as a function of filling. The nearest neighbour attractive Hubbard model on a quasi-2D lattice is studied as a simple phenomenological model for the high-T c cuprates. Mean field theory shows a transition from pure d-wave to pure s-wave superconductivity, via a mixed symmetry s + id state. Using Gaussian fluctuations, the BCS-Bose crossover is examined and suggestions are made about the origin of the angle dependence of the pseudogap. The continuum delta-shell potential model is introduced for anisotropic superconductors. Its mean field phases are studied and found to have some unusual properties. The BCS-Bose crossover is examined and the results are compared with those of the lattice model. Quasi-2D (highly anisotropic 3D) systems are considered. The critical properties of a Bose gas are investigated as the degree of anisotropy is varied. A new 2D Bose condensate state is found. A renormalisation group analysis is used to investigate the crossover from 2D to 3D. (author)
Including the Δ(1232) resonance in baryon chiral perturbation theory
International Nuclear Information System (INIS)
Hacker, C.; Wies, N.; Scherer, S.; Gegelia, J.
2005-01-01
Baryon chiral perturbation theory with explicit Δ(1232) degrees of freedom is considered. The most general interactions of pions, nucleons, and Δ consistent with all underlying symmetries as well as with the constraint structure of higher-spin fields are constructed. By use of the extended on-mass-shell renormalization scheme, a manifestly Lorentz-invariant effective-field theory with a systematic power counting is obtained. As applications, we discuss the mass of the nucleon, the pion-nucleon σ term, and the pole of the Δ propagator
Chirality conservation in the lattice gauge theory
International Nuclear Information System (INIS)
Peskin, M.E.
1978-01-01
The derivation of conservation laws corresponding to chiral invariance in quantum field theories of interacting quarks and gluons are studied. In particular there is interest in observing how these conservation laws are constrained by the requirement that the field theory be locally gauge invariant. To examine this question, a manifestly gauge-invariant definition of local operators in a quantum field theory is introduced, a definition which relies in an essential way on the use of the formulation of gauge fields on a lattice due to Wilson and Polyakov to regulate ultraviolet divergences. The conceptual basis of the formalism is set out and applied to a long-standing puzzle in the phenomenology of quark-gluon theories: the fact that elementary particle interactions reflect the conservation of isospin-carrying chiral currents but not of the isospin-singlet chiral current. It is well known that the equation for the isospin-singlet current contains an extra term, the operator F/sub mu neu/F/sup mu neu/, not present in the other chirality conservation laws; however, this term conventionally has the form of a total divergence and so still allows the definition of a conserved chiral current. It is found that, when the effects of maintaining gauge invariance are properly taken into account, the structure of this operator is altered by renormalization effects, so that it provides an explicit breaking of the unwanted chiral invariance. The relation between this argument, based on renormaliztion, is traced to a set of more heuristic arguments based on gauge field topology given by 't Hooft; it is shown that the discussion provides a validation, through short-distance analysis, of the picture 'Hooft has proposed. The formal derivation of conservation laws for chiral currents are set out in detail
Effective field theory description of halo nuclei
Hammer, H.-W.; Ji, C.; Phillips, D. R.
2017-10-01
Nuclear halos emerge as new degrees of freedom near the neutron and proton driplines. They consist of a core and one or a few nucleons which spend most of their time in the classically-forbidden region outside the range of the interaction. Individual nucleons inside the core are thus unresolved in the halo configuration, and the low-energy effective interactions are short-range forces between the core and the valence nucleons. Similar phenomena occur in clusters of 4He atoms, cold atomic gases near a Feshbach resonance, and some exotic hadrons. In these weakly-bound quantum systems universal scaling laws for s-wave binding emerge that are independent of the details of the interaction. Effective field theory (EFT) exposes these correlations and permits the calculation of non-universal corrections to them due to short-distance effects, as well as the extension of these ideas to systems involving the Coulomb interaction and/or binding in higher angular-momentum channels. Halo nuclei exhibit all these features. Halo EFT, the EFT for halo nuclei, has been used to compute the properties of single-neutron, two-neutron, and single-proton halos of s-wave and p-wave type. This review summarizes these results for halo binding energies, radii, Coulomb dissociation, and radiative capture, as well as the connection of these properties to scattering parameters, thereby elucidating the universal correlations between all these observables. We also discuss how Halo EFT's encoding of the long-distance physics of halo nuclei can be used to check and extend ab initio calculations that include detailed modeling of their short-distance dynamics.
Effective field theory: A modern approach to anomalous couplings
International Nuclear Information System (INIS)
Degrande, Céline; Greiner, Nicolas; Kilian, Wolfgang; Mattelaer, Olivier; Mebane, Harrison; Stelzer, Tim; Willenbrock, Scott; Zhang, Cen
2013-01-01
We advocate an effective field theory approach to anomalous couplings. The effective field theory approach is the natural way to extend the standard model such that the gauge symmetries are respected. It is general enough to capture any physics beyond the standard model, yet also provides guidance as to the most likely place to see the effects of new physics. The effective field theory approach also clarifies that one need not be concerned with the violation of unitarity in scattering processes at high energy. We apply these ideas to pair production of electroweak vector bosons. -- Highlights: •We discuss the advantages of effective field theories compared to anomalous couplings. •We show that one need not be concerned with unitarity violation at high energy. •We discuss the application of effective field theory to weak boson physics
The chiral anomaly from M theory
International Nuclear Information System (INIS)
Guersoy, Umut; Hartnoll, Sean A.; Portugues, Ruben
2004-01-01
We argue that the chiral anomaly of N=1 super Yang-Mills theory admits a dual description as spontaneous symmetry breaking in M theory on G 2 holonomy manifolds. We identify an angle of the G 2 background dual to the anomalous U(1) R current in field theory. This angle is not an isometry of the metric and we therefore develop a theory of 'massive isometry' to describe fluctuations about such angles. Another example of a massive isometry occurs in the Atiyah-Hitchin metric
Dirac operator, chirality and random matrix theory
International Nuclear Information System (INIS)
Pullirsch, R.
2001-05-01
Quantum Chromodynamics (QCD) is considered to be the correct theory which describes quarks and gluons and, thus, all strong interaction phenomena from the fundamental forces of nature. However, important properties of QCD such as the physical mechanism of color confinement and the spontaneous breaking of chiral symmetry are still not completely understood and under extensive discussion. Analytical calculations are limited, because in the low-energy regime where quarks are confined, application of perturbation theory is restricted due to the large gluon coupling. A powerful tool to investigate numerically and analytically the non-perturbative region is provided by the lattice formulation of QCD. From Monte Carlo simulations of lattice QCD we know that chiral symmetry is restored above a critical temperature. As the chiral condensate is connected to the spectral density of the Dirac operator via the Banks-Casher relation, the QCD Dirac spectrum is an interesting object for detailed studies. In search for an analytical expression of the infrared limit of the Dirac spectrum it has been realized that chiral random-matrix theory (chRMT) is a suitable tool to compare with the distribution and the correlations of the small Dirac eigenvalues. Further, it has been shown that the correlations of eigenvalues on the scale of mean level spacings are universal for complex physical systems and are given by random-matrix theory (Rm). This has been formulated as the Baghouse-Giannoni-Schmit conjecture which states that spectral correlations of a classically chaotic system are given by RMT on the quantum level. The aim of this work is to analyze the relationship between chiral phase transitions and chaos to order transitions in quantum field theories. We study the eigenvalues of the Dirac operator for Quantum Electrodynamics (QED) with compact gauge group U(1) on the lattice. This theory shows chiral symmetry breaking and confinement in the strong coupling region. Although being
Theory of conductivity of chiral particles
International Nuclear Information System (INIS)
Kailasvuori, Janik; Šopík, Břetislav; Trushin, Maxim
2013-01-01
In this methodology focused paper we scrutinize the application of the band-coherent Boltzmann equation approach to calculating the conductivity of chiral particles. As the ideal testing ground we use the two-band kinetic Hamiltonian with an N-fold chiral twist that arises in a low-energy description of charge carriers in rhombohedrally stacked multilayer graphene. To understand the role of chirality in the conductivity of such particles we also consider the artificial model with the chiral winding number decoupled from the power of the dispersion. We first utilize the approximate but analytically solvable band-coherent Boltzmann approach including the ill-understood principal value terms that are a byproduct of several quantum many-body theory derivations of Boltzmann collision integrals. Further on, we employ the finite-size Kubo formula with the exact diagonalization of the total Hamiltonian perturbed by disorder. Finally, we compare several choices of Ansatz in the derivation of the Boltzmann equation according to the qualitative agreement between the Boltzmann and Kubo conductivities. We find that the best agreement can be reached in the approach where the principal value terms in the collision integral are absent. (paper)
Baryon form factors in chiral perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Kubis, B.; Meissner, U.G. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Kernphysik
2001-01-01
We analyze the electromagnetic form factors of the ground state baryon octet to fourth order in relativistic baryon chiral perturbation theory. Predictions for the {sigma}{sup -} charge radius and the {lambda}-{sigma}{sup 0} transition moment are found to be in excellent agreement with the available experimental information. Furthermore, the convergence behavior of the hyperon charge radii is shown to be more than satisfactory. (orig.)
The chiral bosonization in non-Abelian gauge theories
International Nuclear Information System (INIS)
Andrianov, A.A.; Novozhilov, Y.
1985-01-01
The chiral bosonization in non-Abelian gauge theories is described starting directly from the QCD functional. For a given mass scale Λ, the QCD may be equivalently represented by colour chiral fields, gauge fields and high energy fermions. The effective action for colour chiral fields may admit the existence of a colour Skyrmion-boson with the baryon number 2/3. (author)
Baryon non-invariant couplings in Higgs effective field theory
International Nuclear Information System (INIS)
Merlo, Luca; Saa, Sara; Sacristan-Barbero, Mario
2017-01-01
The basis of leading operators which are not invariant under baryon number is constructed within the Higgs effective field theory. This list contains 12 dimension six operators, which preserve the combination B - L, to be compared to only 6 operators for the standard model effective field theory. The discussion of the independent flavour contractions is presented in detail for a generic number of fermion families adopting the Hilbert series technique. (orig.)
A lattice formulation of chiral gauge theories
International Nuclear Information System (INIS)
Bodwin, G.T.
1995-12-01
The authors present a method for formulating gauge theories of chiral fermions in lattice field theory. The method makes use of a Wilson mass to remove doublers. Gauge invariance is then restored by modifying the theory in two ways: the magnitude of the fermion determinant is replaced with the square root of the determinant for a fermion with vector-like couplings to the gauge field; a double limit is taken in which the lattice spacing associated with the fermion field is taken to zero before the lattice spacing associated with the gauge field. The method applies only to theories whose fermions are in an anomaly-free representation of the gauge group. They also present a related technique for computing matrix elements of operators involving fermion fields. Although the analyses of these methods are couched in weak-coupling perturbation theory, it is argued that computational prescriptions are gauge invariant in the presence of a nonperturbative gauge-field configuration
Baryon mass splittings in chiral perturbation theory
International Nuclear Information System (INIS)
Banerjee, M.K.; Milana, J.
1995-01-01
Baryon masses are calculated in chiral perturbation theory at the one-loop O(p 3 ) level in chiral expansion and to leading order in the heavy baryon expansion. Ultraviolet divergences occur requiring the introduction of counterterms. Despite this necessity, no knowledge of the counterterms is required to determine the violations of the Gell-Mann--Okubo mass relation for the baryon octet or of the decuplet equal-mass-spacing rule, as all divergences cancel exactly at this order. For the same reason all references to an arbitrary scale μ are absent. Neither of these features continue to higher powers in the chiral expansion. We also discuss critically the absolute necessity of simultaneously going beyond the leading-order heavy baryon expansion, if one goes beyond the one-loop O(p 3 ) level. We point out that these corrections in 1/M B generate new divergences ∝m 4 /M 10 . These divergences together with the divergences occurring in one-loop O(p 4 ) graphs of chiral perturbation theory are taken care of by the same set of counterterms. Because of these unknown counterterms one cannot predict the baryon mass splittings at the one-loop O(p 4 ) level even if the parameters of all scrL 1 πN terms are known. We point out another serious problem of going to the one-loop O(p 4 ) level. When the decuplet is off its mass shell there are additional πNΔ and πΔΔ interaction terms. These interactions contribute to the divergent terms ∝(m 4 /M 10 ), and also to nonanalytic terms such as ∝(m 4 /M 10 )ln(m/M 10 ). Without knowledge of the coupling constants appearing in these interactions, one cannot carry out a consistent one-loop O(p 4 ) level calculation
Chiral anomaly, Berry phase, and chiral kinetic theory from worldlines in quantum field theory
Mueller, Niklas; Venugopalan, Raju
2018-03-01
In previous work, we outlined a worldline framework that can be used for systematic computations of the chiral magnetic effect (CME) in ultrarelativistic heavy-ion collisions. Towards this end, we first expressed the real part of the fermion determinant in the QCD effective action as a supersymmetric worldline action of spinning, colored, Grassmanian point particles in background gauge fields, with equations of motion that are covariant generalizations of the Bargmann-Michel-Telegdi and Wong equations. The chiral anomaly, in contrast, arises from the phase of the fermion determinant. Remarkably, the latter too can be expressed as a point particle worldline path integral, which can be employed to derive the anomalous axial vector current. We will show here how Berry's phase can be obtained in a consistent nonrelativistic adiabatic limit of the real part of the fermion determinant. Our work provides a general first principles demonstration that the topology of Berry's phase is distinct from that of the chiral anomaly confirming prior arguments by Fujikawa in specific contexts. This suggests that chiral kinetic treatments of the CME in heavy-ion collisions that include Berry's phase alone are incomplete. We outline the elements of a worldline covariant relativistic chiral kinetic theory that captures the physics of how the chiral current is modified by many-body scattering and topological fluctuations.
Quark disconnected diagrams in chiral perturbation theory
Della Morte, Michele
2010-01-01
We show how quark-disconnected and quark-connected contributions to hadronic n-point functions can be written as independent correlators for which one can derive expressions in partially quenched chiral effective theory. As an example we apply the idea to the case of the hadronic vacuum polarisation. In particular, we consider the cases of the Nf = 2 theory without and with a partially quenched strange quark and also the Nf = 2 + 1 theory. In the latter two cases a parameter-free prediction for the disconnected contribution at NLO in the effective theory is given. Finally we show how twisted boundary conditions can then be used in lattice QCD to improve the q^2 resolution in the connected contributions even when flavour singlet operators are considered.
Asymptotically safe and free chiral theories with and without scalars
DEFF Research Database (Denmark)
Mølgaard, E.; Sannino, Francesco
2017-01-01
We unveil the dynamics of four-dimensional chiral gauge-Yukawa theories featuring several scalar degrees of freedom transforming according to distinct representations of the underlying gauge group. We consider generalized Georgi-Glashow and Bars-Yankielowicz theories. We determine, to the maximum...... of chiral gauge theories with scalars....
Matching Pion-Nucleon Roy-Steiner Equations to Chiral Perturbation Theory
Hoferichter, Martin; Ruiz de Elvira, Jacobo; Kubis, Bastian; Meißner, Ulf-G.
2015-11-01
We match the results for the subthreshold parameters of pion-nucleon scattering obtained from a solution of Roy-Steiner equations to chiral perturbation theory up to next-to-next-to-next-to-leading order, to extract the pertinent low-energy constants including a comprehensive analysis of systematic uncertainties and correlations. We study the convergence of the chiral series by investigating the chiral expansion of threshold parameters up to the same order and discuss the role of the Δ (1232 ) resonance in this context. Results for the low-energy constants are also presented in the counting scheme usually applied in chiral nuclear effective field theory, where they serve as crucial input to determine the long-range part of the nucleon-nucleon potential as well as three-nucleon forces.
More effective field theory for non-relativistic scattering
International Nuclear Information System (INIS)
Kaplan, D.B.
1997-01-01
An effective field theory treatment of nucleon-nucleon scattering at low energy shows much promise and could prove to be a useful tool in the study of nuclear matter at both ordinary and extreme densities. The analysis is complicated by the existence a large length scale - the scattering length -which arises due to couplings in the short distance theory being near critical values. I show how this can be dealt with by introducing an explicit s-channel state in the effective field theory. The procedure is worked out analytically in a toy example. I then demonstrate that a simple effective field theory excellently reproduces the 1 S 0 np phase shift up to the pion production threshold. (orig.)
Chiral perturbation theory for lattice QCD
International Nuclear Information System (INIS)
Baer, Oliver
2010-01-01
The formulation of chiral perturbation theory (ChPT) for lattice Quantum Chromodynamics (QCD) is reviewed. We start with brief summaries of ChPT for continuum QCD as well as the Symanzik effective theory for lattice QCD. We then review the formulation of ChPT for lattice QCD. After an additional chapter on partial quenching and mixed action theories various concrete applications are discussed: Wilson ChPT, staggered ChPT and Wilson ChPT with a twisted mass term. The remaining chapters deal with the epsilon regime with Wilson fermions and selected results in mixed action ChPT. Finally, the formulation of heavy vector meson ChPT with Wilson fermions is discussed. (orig.)
Chiral perturbation theory for lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Baer, Oliver
2010-07-21
The formulation of chiral perturbation theory (ChPT) for lattice Quantum Chromodynamics (QCD) is reviewed. We start with brief summaries of ChPT for continuum QCD as well as the Symanzik effective theory for lattice QCD. We then review the formulation of ChPT for lattice QCD. After an additional chapter on partial quenching and mixed action theories various concrete applications are discussed: Wilson ChPT, staggered ChPT and Wilson ChPT with a twisted mass term. The remaining chapters deal with the epsilon regime with Wilson fermions and selected results in mixed action ChPT. Finally, the formulation of heavy vector meson ChPT with Wilson fermions is discussed. (orig.)
Global anomalies in chiral lattice gauge theories
International Nuclear Information System (INIS)
Baer, O.
2000-07-01
We study global anomalies in a new approach to chiral gauge theories on the lattice, which is based on the Ginsparg-Wilson relation. In this approach, global anomalies make it impossible to define consistently a fermionic measure for the functional integral. We show that a global anomaly occurs in an SU(2) theory if the fundamental representation is used for the fermion fields. The generalization to higher representations is also discussed. In addition we establish a close relation between global anomalies and the spectral flow of the Dirac operator and employ it in a numerical computation to prove the existence of the global SU(2) anomaly in a different way. This method is inspired by an earlier work of Witten who first discovered this type of anomalies in continuum field theory. (orig.)
Chiral perturbation theory for nucleon generalized parton distributions
Energy Technology Data Exchange (ETDEWEB)
Diehl, M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Manashov, A. [Regensburg Univ. (Germany). Inst. fuer Physik 1 - Theoretische Physik]|[Sankt-Petersburg State Univ. (Russian Federation). Dept. of Theoretical Physics; Schaefer, A. [Regensburg Univ. (Germany). Inst. fuer Physik 1 - Theoretische Physik
2006-08-15
We analyze the moments of the isosinglet generalized parton distributions H, E, H, E of the nucleon in one-loop order of heavy-baryon chiral perturbation theory. We discuss in detail the construction of the operators in the effective theory that are required to obtain all corrections to a given order in the chiral power counting. The results will serve to improve the extrapolation of lattice results to the chiral limit. (orig.)
arXiv Chiral Effective Theory of Dark Matter Direct Detection
Bishara, Fady
2017-02-03
We present the effective field theory for dark matter interactions with the visible sector that is valid at scales of O(1 GeV). Starting with an effective theory describing the interactions of fermionic and scalar dark matter with quarks, gluons and photons via higher dimension operators that would arise from dimension-five and dimension-six operators above electroweak scale, we perform a nonperturbative matching onto a heavy baryon chiral perturbation theory that describes dark matter interactions with light mesons and nucleons. This is then used to obtain the coefficients of the nuclear response functions using a chiral effective theory description of nuclear forces. Our results consistently keep the leading contributions in chiral counting for each of the initial Wilson coefficients.
Effective field theory of interactions on the lattice
DEFF Research Database (Denmark)
Valiente, Manuel; Zinner, Nikolaj T.
2015-01-01
We consider renormalization of effective field theory interactions by discretizing the continuum on a tight-binding lattice. After studying the one-dimensional problem, we address s-wave collisions in three dimensions and relate the bare lattice coupling constants to the continuum coupling consta...... constants. Our method constitutes a very simple avenue for the systematic renormalization in effective field theory, and is especially useful as the number of interaction parameters increases.......We consider renormalization of effective field theory interactions by discretizing the continuum on a tight-binding lattice. After studying the one-dimensional problem, we address s-wave collisions in three dimensions and relate the bare lattice coupling constants to the continuum coupling...
Threshold resummation for Higgs production in effective field theory
International Nuclear Information System (INIS)
Idilbi, Ahmad; Ji Xiangdong; Ma Jianping; Yuan Feng
2006-01-01
We present an effective field theory approach to resum the large double logarithms originated from soft-gluon radiations at small final-state hadron invariant masses in Higgs and vector boson (γ*,W,Z) production at hadron colliders. The approach is conceptually simple, independent of details of an effective field theory formulation, and valid to all orders in subleading logarithms. As an example, we show the result of summing the next-to-next-to-next-to leading logarithms is identical to that of the standard pQCD factorization method
Consistent constraints on the Standard Model Effective Field Theory
International Nuclear Information System (INIS)
Berthier, Laure; Trott, Michael
2016-01-01
We develop the global constraint picture in the (linear) effective field theory generalisation of the Standard Model, incorporating data from detectors that operated at PEP, PETRA, TRISTAN, SpS, Tevatron, SLAC, LEPI and LEP II, as well as low energy precision data. We fit one hundred and three observables. We develop a theory error metric for this effective field theory, which is required when constraints on parameters at leading order in the power counting are to be pushed to the percent level, or beyond, unless the cut off scale is assumed to be large, Λ≳ 3 TeV. We more consistently incorporate theoretical errors in this work, avoiding this assumption, and as a direct consequence bounds on some leading parameters are relaxed. We show how an S,T analysis is modified by the theory errors we include as an illustrative example.
Chiral rings and anomalies in supersymmetric gauge theory
International Nuclear Information System (INIS)
Cachazo, Freddy; Witten, Edward; Seiberg, Nathan; Douglas, Michael R.
2002-01-01
Motivated by recent work of Dijkgraaf and Vafa, we study anomalies and the chiral ring structure in a supersymmetric U(N) gauge theory with an adjoint chiral superfield and an arbitrary superpotential. A certain generalization of the Konishi anomaly leads to an equation which is identical to the loop equation of a bosonic matrix model. This allows us to solve for the expectation values of the chiral operators as functions of a finite number of 'integration constants'. From this, we can derive the Dijkgraaf-Vafa relation of the effective superpotential to a matrix model. Some of our results are applicable to more general theories. For example, we determine the classical relations and quantum deformations of the chiral ring of N=1 super Yang-Mills theory with SU(N) gauge group, showing, as one consequence, that all supersymmetric vacua of this theory have a nonzero chiral condensate. (author)
On the exotic Higgs decays in effective field theory.
Bélusca-Maïto, Hermès; Falkowski, Adam
2016-01-01
We discuss exotic Higgs decays in an effective field theory where the Standard Model is extended by dimension-6 operators. We review and update the status of two-body lepton- and quark-flavor-violating decays involving the Higgs boson. We also comment on the possibility of observing three-body flavor-violating Higgs decays in this context.
On the exotic Higgs decays in effective field theory
Energy Technology Data Exchange (ETDEWEB)
Belusca-Maito, Hermes; Falkowski, Adam [Universite Paris-Sud, Laboratoire de Physique Theorique, Orsay (France)
2016-09-15
We discuss exotic Higgs decays in an effective field theory where the Standard Model is extended by dimension-6 operators. We review and update the status of two-body lepton- and quark-flavor-violating decays involving the Higgs boson. We also comment on the possibility of observing three-body flavor-violating Higgs decays in this context. (orig.)
Effective Field Theories and Strong Interactions. Final Technical Report
International Nuclear Information System (INIS)
Fleming, Sean
2011-01-01
The framework of Effective Field Theories (EFTs) allows us to describe strong interactions in terms of degrees of freedom relevant to the energy regimes of interest, in the most general way consistent with the symmetries of QCD. Observables are expanded systematically in powers of M lo /M hi , where M lo (M hi ) denotes a low-(high-)energy scale. This organizational principle is referred to as 'power counting'. Terms of increasing powers in the expansion parameter are referred to as leading order (LO), next-to-leading order (NLO), etc. Details of the QCD dynamics not included explicitly are encoded in interaction parameters, or 'low-energy constants' (LECs), which can in principle be calculated from an explicit solution of QCD - for example via lattice simulations- but can also be determined directly from experimental data. QCD has an intrinsic scale M QCD ≅ 1 GeV, at which the QCD coupling constant α s (M QCD ) becomes large and the dynamics becomes non-perturbative. As a consequence M QCD sets the scale for the masses of most hadrons, such as the nucleon mass m N ≅ 940 MeV. EFTs can roughly be divided into two categories: those that can be matched onto QCD in perturbation theory, which we call high-energy EFTs, and those that cannot be matched perturbatively, which we call low-energy EFTs. In high-energy EFTs, M QCD typically sets the low-energy scale, and all the dynamics associated with this scale reside in matrix elements of EFT operators. These non-perturbative matrix elements are the LECs and are also referred to as long-distance contributions. Each matrix element is multiplied by a short-distance coefficient, which contains the dynamics from the high scale M hi . Since M hi >> M QCD , α s (M hi ) hi ∼ M Q , the heavy-quark mass, and in addition to M QCD there are low scales associated with the typical relative momentum ∼ M Q v and energy ∼ M Q v 2 of the heavy quarks. Depending on the sizes of M Q and the heavy-quark velocity v these scales can
Uses of Effective Field Theory in Lattice QCD
Kronfeld, Andreas S.
2002-01-01
Several physical problems in particle physics, nuclear physics, and astrophysics require information from non-perturbative QCD to gain a full understanding. In some cases the most reliable technique for quantitative results is to carry out large-scale numerical calculations in lattice gauge theory. As in any numerical technique, there are several sources of uncertainty. This chapter explains how effective field theories are used to keep them under control and, then, obtain a sensible error ba...
Naturalness in an Effective Field Theory for Neutron Star Matter
International Nuclear Information System (INIS)
Razeira, Moises; Vasconcellos, Cesar A.Z.; Bodmann, Bardo E.J.; Coelho, Helio T.; Dillig, Manfred
2004-01-01
High density hadronic matter is studied in a generalized relativistic multi-baryon lagrangian density. By comparing the predictions of our model with estimates obtained within a phenomenological naive dimensional analysis based on the naturalness of the coefficients of the theory, we show that naturalness plays a major role in effective field theory and, in combination with experiment, could represent a relevant criterium to select a model among others in the description of global static properties of neutron stars
On the overlap formulation of chiral gauge theory
International Nuclear Information System (INIS)
Randjbar Daemi, S.; Strathdee, J.
1994-12-01
The overlap formula proposed by Narayanan and Neuberger in chiral gauge theories is examined. The free chiral and Dirac Green's functions are constructed in this formalism. Four dimensional anomalies are calculated and the usual anomaly cancellation for one standard family of quarks and leptons is verified. (author). 4 refs
On the effective field theory of intersecting D3-branes
Abbaspur, Reza
2018-05-01
We study the effective field theory of two intersecting D3-branes with one common dimension along the lines recently proposed in ref. [1]. We introduce a systematic way of deriving the classical effective action to arbitrary orders in perturbation theory. Using a proper renormalization prescription to handle logarithmic divergencies arising at all orders in the perturbation series, we recover the first order renormalization group equation of ref. [1] plus an infinite set of higher order equations. We show the consistency of the higher order equations with the first order one and hence interpret the first order result as an exact RG flow equation in the classical theory.
Vanishing chiral couplings in the large-NC resonance theory
International Nuclear Information System (INIS)
Portoles, Jorge; Rosell, Ignasi; Ruiz-Femenia, Pedro
2007-01-01
The construction of a resonance theory involving hadrons requires implementing the information from higher scales into the couplings of the effective Lagrangian. We consider the large-N C chiral resonance theory incorporating scalars and pseudoscalars, and we find that, by imposing LO short-distance constraints on form factors of QCD currents constructed within this theory, the chiral low-energy constants satisfy resonance saturation at NLO in the 1/N C expansion
Effective-field theory on the kinetic Ising model
International Nuclear Information System (INIS)
Shi Xiaoling; Wei Guozhu; Li Lin
2008-01-01
As an analytical method, the effective-field theory (EFT) is used to study the dynamical response of the kinetic Ising model in the presence of a sinusoidal oscillating field. The effective-field equations of motion of the average magnetization are given for the square lattice (Z=4) and the simple cubic lattice (Z=6), respectively. The dynamic order parameter, the hysteresis loop area and the dynamic correlation are calculated. In the field amplitude h 0 /ZJ-temperature T/ZJ plane, the phase boundary separating the dynamic ordered and the disordered phase has been drawn, and the dynamical tricritical point has been observed. We also make the compare results of EFT with that given by using the mean field theory (MFT)
Parameter-free effective field theory calculation for the solar proton-fusion and hep processes
International Nuclear Information System (INIS)
T.S. Park; L.E. Marcucci; R. Schiavilla; M. Viviani; A. Kievsky; S. Rosati; K. Kubodera; D.P. Min; M. Rho
2002-01-01
Spurred by the recent complete determination of the weak currents in two-nucleon systems up to Ο(Q 3 ) in heavy-baryon chiral perturbation theory, we carry out a parameter-free calculation of the threshold S-factors for the solar pp (proton-fusion) and hep processes in an effective field theory that combines the merits of the standard nuclear physics method and systematic chiral expansion. The power of the EFT adopted here is that one can correlate in a unified formalism the weak-current matrix elements of two-, three- and four-nucleon systems. Using the tritium β-decay rate as an input to fix the only unknown parameter in the theory, we can evaluate the threshold S factors with drastically improved precision; the results are S pp (0) = 3.94 x (1 ± 0.004) x 10 -25 MeV-b and S hep (0) = (8.6 ± 1.3) x 10 -20 keV-b. The dependence of the calculated S-factors on the momentum cutoff parameter Λ has been examined for a physically reasonable range of Λ. This dependence is found to be extremely small for the pp process, and to be within acceptable levels for the hep process, substantiating the consistency of our calculational scheme
A note on nonperturbative renormalization of effective field theory
Energy Technology Data Exchange (ETDEWEB)
Yang Jifeng [Department of Physics, East China Normal University, Shanghai 200062 (China)
2009-08-28
Within the realm of contact potentials, the key structures intrinsic of nonperturbative renormalization of T-matrices are unraveled using rigorous solutions and an inverse form of the algebraic Lippmann-Schwinger equation. The intrinsic mismatches between effective field theory power counting and nonperturbative divergence structures are shown for the first time to preclude the conventional counterterm algorithm from working in the renormalization of EFT for NN scattering in nonperturbative regimes.
A note on nonperturbative renormalization of effective field theory
International Nuclear Information System (INIS)
Yang Jifeng
2009-01-01
Within the realm of contact potentials, the key structures intrinsic of nonperturbative renormalization of T-matrices are unraveled using rigorous solutions and an inverse form of the algebraic Lippmann-Schwinger equation. The intrinsic mismatches between effective field theory power counting and nonperturbative divergence structures are shown for the first time to preclude the conventional counterterm algorithm from working in the renormalization of EFT for NN scattering in nonperturbative regimes.
An effective field theory for the neutron electric dipole moment
International Nuclear Information System (INIS)
Chang, D.; Kephart, T.W.; Keung, W.Y.; Yuan, T.C.
1992-01-01
We derive a CP-odd effective field theory involving the field strengths of the gluon and the photon and their duals as a result of integrating out a heavy quark which carries both the chromo-electric dipole moment and electric dipole moment. The coefficients of the induced gluonic, photonic, and mixed gluon-photon operators with dimension ≤ 8 are determined. Implications of some of these operators on the neutron electric dipole moment are also discussed. (orig.)
The renormalization group in effective chiral theories
International Nuclear Information System (INIS)
Varin, T.
2007-09-01
The dilepton production within the heavy ions collisions (CERN/SPS, SIS/HADES, RHIC) and the behaviour of vector mesons (in particular the rho meson) are among the main topics of quantum chromodynamics (QCD) in hadronic matter. One of the main goals is the study of partial or total restoration of chiral symmetry SU(2) x SU(2), for which effective theories need to be used. One of the important difficulties is to build a theory which allows to obtain predictions when approaching the phase transition by taking into account the phenomenological constraints at low temperature and/or density. The model used here (developed by M. Urban) is based on the gauged (rho and al mesons) linear sigma model adjusted (in practice the local symmetry is only approximate) to reproduce the phenomenology very well. The first part of this thesis consists in presenting a new cut-off based regularization scheme preserving symmetry requirements. The motivation of such a method is a correct accounting of quadratic and logarithmic divergences in view of their intensive use for the renormalisation group equations. For illustrative purposes we have applied it to QED in 4 and 5 dimensions. The second part of this work is devoted to the derivation of the RGE and their resolution. In particular, we show that both restorations (traditional and vector manifestation) can be obtained from our equations, but the most likely remains the 'traditional' Ginzburg-Landau scenario. (author)
Soft-collinear factorization in effective field theory
International Nuclear Information System (INIS)
Bauer, Christian W.; Pirjol, Dan; Stewart, Iain W.
2002-01-01
The factorization of soft and ultrasoft gluons from collinear particles is shown at the level of operators in an effective field theory. Exclusive hadronic factorization and inclusive partonic factorization follow as special cases. The leading-order Lagrangian is derived using power counting and gauge invariance in the effective theory. Several species of gluons are required, and softer gluons appear as background fields to gluons with harder momenta. Two examples are given: the factorization of soft gluons in B→Dπ and the soft-collinear convolution for the B→X s γ spectrum
Standard model and chiral gauge theories on the lattice
International Nuclear Information System (INIS)
Smit, J.
1990-01-01
A review is given of developments in lattice formulations of chiral gauge theories. There is now evidence that the unwanted fermion doublers can be decoupled satisfactorily by giving them masses of the order of the cutoff. (orig.)
Correlated effective field theory in transition metal compounds
International Nuclear Information System (INIS)
Mukhopadhyay, Subhasis; Chatterjee, Ibha
2004-01-01
Mean field theory is good enough to study the physical properties at higher temperatures and in higher dimensions. It explains the critical phenomena in a restricted sense. Near the critical temperatures, when fluctuations become important, it may not give the correct results. Similarly in low dimensions, the correlations become important and the mean field theory seems to be inadequate to explain the physical phenomena. At low-temperatures too, the quantum correlations become important and these effects are to be treated in an appropriate way. In 1974, Prof. M.E. Lines of Bell Laboratories, developed a theory which goes beyond the mean field theory and is known as the correlated effective field (CEF) theory. It takes into account the fluctuations in a semiempirical way. Lines and his collaborators used this theory to explain the short-range correlations and their anisotropy in the paramagnetic phase. Later Suzuki et al., Chatterjee and Desai, Mukhopadhyay and Chatterjee applied this theory to the magnetically ordered phase and a tremendous success of the theory has been found in real systems. The success of the CEF theory is discussed in this review. In order to highlight the success of this theory, earlier effective field theories and their improvements over mean field theories e.g., Bethe-Peierls-Weiss method, reaction field approximation, etc., are also discussed in this review for completeness. The beauty of the CEF theory is that it is mean field-like, but captures the essential physics of real systems to a great extent. However, this is a weak correlated theory and as a result is inappropriate for the metallic phase when strong correlations become important. In recent times, transition metal oxides become important due to the discovery of the high-temperature superconductivity and the colossal magnetoresistance phenomena. These oxides seem to be Mott insulators and undergo an insulator to metal transition by applying magnetic field, pressure and by changing
Sigma exchange in the nuclear force and effective field theory
International Nuclear Information System (INIS)
Donoghue, John F.
2006-01-01
In the phenomenological description of the nuclear interaction an important role is traditionally played by the exchange of a scalar I=0 meson, the sigma, of mass 500-600 MeV, which however is not seen clearly in the particle spectrum and which has a very ambiguous status in QCD. I show that a remarkably simple and reasonably controlled combination of ingredients can reproduce the features of this part of the nuclear force. The use of chiral perturbation theory calculations for two pion exchange supplemented by the Omnes function for pion rescattering suffices to reproduce the magnitude and shape of the exchange of a supposed σ particle. I also attempt to relate this description to the contact interaction that enters more modern descriptions of the internucleon interaction
Nucleon and delta masses in twisted mass chiral perturbation theory
International Nuclear Information System (INIS)
Walker-Loud, Andre; Wu, Jackson M.S.
2005-01-01
We calculate the masses of the nucleons and deltas in twisted mass heavy baryon chiral perturbation theory. We work to quadratic order in a power counting scheme in which we treat the lattice spacing, a, and the quark masses, m q , to be of the same order. We give expressions for the mass and the mass splitting of the nucleons and deltas both in and away from the isospin limit. We give an argument using the chiral Lagrangian treatment that, in the strong isospin limit, the nucleons remain degenerate and the delta multiplet breaks into two degenerate pairs to all orders in chiral perturbation theory. We show that the mass splitting between the degenerate pairs of the deltas first appears at quadratic order in the lattice spacing. We discuss the subtleties in the effective chiral theory that arise from the inclusion of isospin breaking
The role of resonances in chiral perturbation theory
International Nuclear Information System (INIS)
Ecker, G.; Rafael, E. de
1988-09-01
The strong interactions of low-lying meson resonances (spin ≤ 1) with the octet of pseudoscalar mesons (π,Κ,η) are considered to lowest order in the derivative expansion of chiral SU(3). The resonance contributions to the coupling constants of the O(p 4 ) effective chiral lagrangian involving pseudoscalar fields only are determined. These low-energy coupling constants are found to be dominated by the resonance contributions. Although we do not treat the vector and axial-vector mesons as gauge bosons of local chiral symmetry, vector meson dominance emerges as a prominent result of our analysis. As a further application of chiral resonance couplings, we calculate the electromagnetic pion mass difference to lowest order in chiral perturbation theory with explicit resonance fields. 29 refs., 2 figs., 5 tabs. (Author)
Off-shell renormalization in Higgs effective field theories
Binosi, Daniele; Quadri, Andrea
2018-04-01
The off-shell one-loop renormalization of a Higgs effective field theory possessing a scalar potential ˜ {({Φ}^{\\dagger}Φ -υ^2/2)}^N with N arbitrary is presented. This is achieved by renormalizing the theory once reformulated in terms of two auxiliary fields X 1,2, which, due to the invariance under an extended Becchi-Rouet-Stora-Tyutin symmetry, are tightly constrained by functional identities. The latter allow in turn the explicit derivation of the mapping onto the original theory, through which the (divergent) multi-Higgs amplitude are generated in a purely algebraic fashion. We show that, contrary to naive expectations based on the loss of power counting renormalizability, the Higgs field undergoes a linear Standard Model like redefinition, and evaluate the renormalization of the complete set of Higgs self-coupling in the N → ∞ case.
Effective Field Theories for Hot and Dense Matter
Directory of Open Access Journals (Sweden)
Blaschke D.
2010-10-01
Full Text Available The lecture is divided in two parts. The ﬁrst one deals with an introduction to the physics of hot, dense many-particle systems in quantum ﬁeld theory [1, 2]. The basics of the path integral approach to the partition function are explained for the example of chiral quark models. The QCD phase diagram is discussed in the meanﬁeld approximation while QCD bound states in the medium are treated in the rainbow-ladder approximation (Gaussian ﬂuctuations. Special emphasis is devoted to the discussion of the Mott eﬀect, i.e. the transition of bound states to unbound, but resonant scattering states in the continnum under the inﬂuence of compression and heating of the system. Three examples are given: (1 the QCD model phase diagram with chiral symmetry ¨ restoration and color superconductivity [3], (2 the Schrodinger equation for heavy-quarkonia [4], and (2 Pions [5] as well as Kaons and D-mesons in the ﬁnite-temperature Bethe-Salpeter equation [6]. We discuss recent applications of this quantum ﬁeld theoretical approach to hot and dense quark matter for a description of anomalous J/ψ supression in heavy-ion collisions [7] and for the structure and cooling of compact stars with quark matter interiors [8]. The second part provides a detailed introduction to the Polyakov-loop Nambu–Jona-Lasinio model [9] for thermodynamics and mesonic correlations [10] in the phase diagram of quark matter. Important relationships of low-energy QCD like the Gell-Mann–Oakes–Renner relation are generalized to ﬁnite temperatures. The eﬀect of including the coupling to the Polyakov-loop potential on the phase diagram and mesonic correlations is discussed. An outlook is given to eﬀects of nonlocality of the interactions [11] and of mesonic correlations in the medium [12] which go beyond the meanﬁeld description.
The effective field theory of cosmological large scale structures
Energy Technology Data Exchange (ETDEWEB)
Carrasco, John Joseph M. [Stanford Univ., Stanford, CA (United States); Hertzberg, Mark P. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Senatore, Leonardo [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
2012-09-20
Large scale structure surveys will likely become the next leading cosmological probe. In our universe, matter perturbations are large on short distances and small at long scales, i.e. strongly coupled in the UV and weakly coupled in the IR. To make precise analytical predictions on large scales, we develop an effective field theory formulated in terms of an IR effective fluid characterized by several parameters, such as speed of sound and viscosity. These parameters, determined by the UV physics described by the Boltzmann equation, are measured from N-body simulations. We find that the speed of sound of the effective fluid is c^{2}_{s} ≈ 10^{–6}c^{2} and that the viscosity contributions are of the same order. The fluid describes all the relevant physics at long scales k and permits a manifestly convergent perturbative expansion in the size of the matter perturbations δ(k) for all the observables. As an example, we calculate the correction to the power spectrum at order δ(k)^{4}. As a result, the predictions of the effective field theory are found to be in much better agreement with observation than standard cosmological perturbation theory, already reaching percent precision at this order up to a relatively short scale k ≃ 0.24h Mpc^{–1}.
Reconstructing inflationary paradigm within Effective Field Theory framework
Choudhury, Sayantan
2016-03-01
In this paper my prime objective is to analyse the constraints on a sub-Planckian excursion of a single inflaton field within Effective Field Theory framework in a model independent fashion. For a generic single field inflationary potential, using the various parameterization of the primordial power spectrum I have derived the most general expression for the field excursion in terms of various inflationary observables, applying the observational constraints obtained from recent Planck 2015 and Planck 2015 + BICEP2/Keck Array data. By explicit computation I have reconstructed the structural form of the inflationary potential by constraining the Taylor expansion co-efficients appearing in the generic expansion of the potential within the Effective Field Theory. Next I have explicitly derived, a set of higher order inflationary consistency relationships, which would help us to break the degeneracy between various class of inflationary models by differentiating them. I also provided two simple examples of Effective Theory of inflation- inflection-point model and saddle-point model to check the compatibility of the prescribed methodology in the light of Planck 2015 and Planck 2015 + BICEP2/Keck Array data. Finally, I have also checked the validity of the prescription by estimating the cosmological parameters and fitting the theoretical CMB TT, TE and EE angular power spectra with the observed data within the multipole range 2 < l < 2500.
The effective field theory of nonsingular cosmology: II
Energy Technology Data Exchange (ETDEWEB)
Cai, Yong; Li, Hai-Guang [University of Chinese Academy of Sciences, School of Physics, Beijing (China); Qiu, Taotao [Central China Normal University, Institute of Astrophysics, Wuhan (China); Piao, Yun-Song [University of Chinese Academy of Sciences, School of Physics, Beijing (China); Chinese Academy of Sciences, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China)
2017-06-15
Based on the effective field theory (EFT) of cosmological perturbations, we explicitly clarify the pathology in nonsingular cubic Galileon models and show how to cure it in EFT with new insights into this issue. With the least set of EFT operators that are capable to avoid instabilities in nonsingular cosmologies, we construct a nonsingular model dubbed the Genesis-inflation model, in which a slowly expanding phase (namely, Genesis) with increasing energy density is followed by slow-roll inflation. The spectrum of the primordial perturbation may be simulated numerically, which shows itself a large-scale cutoff, as the large-scale anomalies in CMB might be a hint for. (orig.)
Effective field theory of dark matter from membrane inflationary paradigm
Choudhury, Sayantan; Dasgupta, Arnab
2016-09-01
In this article, we have studied the cosmological and particle physics constraints on dark matter relic abundance from effective field theory of inflation from tensor-to-scalar ratio (r), in case of Randall-Sundrum single membrane (RSII) paradigm. Using semi-analytical approach we establish a direct connection between the dark matter relic abundance (ΩDMh2) and primordial gravity waves (r), which establishes a precise connection between inflation and generation of dark matter within the framework of effective field theory in RSII membrane. Further assuming the UV completeness of the effective field theory perfectly holds good in the prescribed framework, we have explicitly shown that the membrane tension, σ ≤ O(10-9) Mp4 , bulk mass scale M5 ≤ O(0.04 - 0.05) Mp, and cosmological constant Λ˜5 ≥ - O(10-15) Mp5 , in RSII membrane plays the most significant role to establish the connection between dark matter and inflation, using which we have studied the features of various mediator mass scale suppressed effective field theory "relevant operators" induced from the localized s, t and u channel interactions in RSII membrane. Taking a completely model independent approach, we have studied an exhaustive list of tree-level Feynman diagrams for dark matter annihilation within the prescribed setup and to check the consistency of the obtained results, further we apply the constraints as obtained from recently observed Planck 2015 data and Planck + BICEP2 + Keck Array joint data sets. Using all of these derived results we have shown that to satisfy the bound on, ΩDMh2 = 0.1199 ± 0.0027, as from Planck 2015 data, it is possible to put further stringent constraint on r within, 0.01 ≤ r ≤ 0.12, for thermally averaged annihilation cross-section of dark matter, 〈 σv 〉 ≈ O(10-28 - 10-27) cm3 / s, which are very useful to constrain various membrane inflationary models.
Chiral gauge theory on AdS domain wall
International Nuclear Information System (INIS)
Shirman, Yuri
2005-01-01
We describe a realization of chiral gauge theories based on the domaim wall fermion construction implemented on an interval in five dimensional AdS spacetime. At semi-classical level deconstructed description of the theory is given in terms of 4-dimensional Minkowski slices supporting chiral zero modes at the ends. Energy scales warp down along the fifth dimension. When the theory is augmented by 4-dimensional neutral Majorana spinors together with the Higgs mechanism at the low energy end, we can arrange for a theory where the lightest gauge boson mode as well as chiral zero mode at the high energy end are parametrically lighter than other states. Triangle anomalies and instanton effects are expected to make gauge bosons heavy if the resulting effective theory is anomalous. Due to the strong coupling effects at the quantum level, full non-perturbative calculation will be necessary to validate this construction
Hyperon decay form factors in chiral perturbation theory
International Nuclear Information System (INIS)
Lacour, Andre; Kubis, Bastian; Meissner, Ulf-G.
2007-01-01
We present a complete calculation of the SU(3)-breaking corrections to the hyperon vector form factors up to O(p 4 ) in covariant baryon chiral perturbation theory. Partial higher-order contributions are obtained, and we discuss chiral extrapolations of the vector form factor at zero momentum transfer. In addition we derive low-energy theorems for the subleading moments in hyperon decays, the weak Dirac radii and the weak anomalous magnetic moments, up to O(p 4 )
DsixTools: the standard model effective field theory toolkit
Energy Technology Data Exchange (ETDEWEB)
Celis, Alejandro [Ludwig-Maximilians-Universitaet Muenchen, Fakultaet fuer Physik, Arnold Sommerfeld Center for Theoretical Physics, Munich (Germany); Fuentes-Martin, Javier; Vicente, Avelino [Universitat de Valencia-CSIC, Instituto de Fisica Corpuscular, Valencia (Spain); Virto, Javier [University of Bern, Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, Bern (Switzerland)
2017-06-15
We present DsixTools, a Mathematica package for the handling of the dimension-six standard model effective field theory. Among other features, DsixTools allows the user to perform the full one-loop renormalization group evolution of the Wilson coefficients in the Warsaw basis. This is achieved thanks to the SMEFTrunner module, which implements the full one-loop anomalous dimension matrix previously derived in the literature. In addition, DsixTools also contains modules devoted to the matching to the ΔB = ΔS = 1, 2 and ΔB = ΔC = 1 operators of the Weak Effective Theory at the electroweak scale, and their QCD and QED Renormalization group evolution below the electroweak scale. (orig.)
Standard model effective field theory: Integrating out neutralinos and charginos in the MSSM
Han, Huayong; Huo, Ran; Jiang, Minyuan; Shu, Jing
2018-05-01
We apply the covariant derivative expansion method to integrate out the neutralinos and charginos in the minimal supersymmetric Standard Model. The results are presented as set of pure bosonic dimension-six operators in the Standard Model effective field theory. Nontrivial chirality dependence in fermionic covariant derivative expansion is discussed carefully. The results are checked by computing the h γ γ effective coupling and the electroweak oblique parameters using the Standard Model effective field theory with our effective operators and direct loop calculation. In global fitting, the proposed lepton collider constraint projections, special phenomenological emphasis is paid to the gaugino mass unification scenario (M2≃2 M1) and anomaly mediation scenario (M1≃3.3 M2). These results show that the precision measurement experiments in future lepton colliders will provide a very useful complementary job in probing the electroweakino sector, in particular, filling the gap of the soft lepton plus the missing ET channel search left by the traditional collider, where the neutralino as the lightest supersymmetric particle is very degenerated with the next-to-lightest chargino/neutralino.
Disoriented chiral condensate: Theory and phenomenology
International Nuclear Information System (INIS)
Bjorken, J.D.
1997-12-01
These notes are an abbreviated version of lectures given at the 1997 Zakopane School. They contain two topics. The first is a description in elementary terms of the basic ideas underlying the speculative hypothesis that pieces of strong-interaction vacuum with a rotated chiral order parameter, disoriented chiral condensate or DCC, might be produced in high energy elementary particle collisions. The second topic is a discussion of the phenomenological techniques which may be applied to data in order to experimentally search for the existence of DCC
Is the effective field theory of dark energy effective?
Energy Technology Data Exchange (ETDEWEB)
Linder, Eric V. [Berkeley Center for Cosmological Physics and Berkeley Lab, University of California, New Campbell Hall 341, Berkeley, CA, 94720 (United States); Sengör, Gizem; Watson, Scott, E-mail: evlinder@lbl.gov, E-mail: gsengor@syr.edu, E-mail: gswatson@syr.edu [Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY, 13244 (United States)
2016-05-01
The effective field theory of cosmic acceleration systematizes possible contributions to the action, accounting for both dark energy and modifications of gravity. Rather than making model dependent assumptions, it includes all terms, subject to the required symmetries, with four (seven) functions of time for the coefficients. These correspond respectively to the Horndeski and general beyond Horndeski class of theories. We address the question of whether this general systematization is actually effective, i.e. useful in revealing the nature of cosmic acceleration when compared with cosmological data. The answer is no and yes: there is no simple time dependence of the free functions —assumed forms in the literature are poor fits, but one can derive some general characteristics in early and late time limits. For example, we prove that the gravitational slip must restore to general relativity in the de Sitter limit of Horndeski theories, and why it doesn't more generally. We also clarify the relation between the tensor and scalar sectors, and its important relation to observations; in a real sense the expansion history H ( z ) or dark energy equation of state w ( z ) is 1/5 or less of the functional information! In addition we discuss the de Sitter, Horndeski, and decoupling limits of the theory utilizing Goldstone techniques.
Tumbling and complementarity in a chiral gauge theory
International Nuclear Information System (INIS)
Goity, J.; Peccei, R.D.; Zeppenfeld, D.
1985-06-01
We consider in detail a chiral SU(N) gauge theory which undergoes multiple tumbling. An extension of the notion of complementarity is used which allows us to deduce the set of massless fermions, in the confining phase of the theory, which we needed for anomaly matching. The likelyhood of this confining phase ever being realized in practice is discussed. (orig.)
Playing with QCD I: effective field theories. Third lecture
International Nuclear Information System (INIS)
Fraga, Eduardo S.
2009-01-01
One can construct useful effective models to describe the deconfining transition using the Polyakov loop as the building block. This procedure was generalized to a matrix model approach, including fermions as a background field (not discussed here). The chiral transition can be described using the chiral condensate as the order parameter. Nonzero (even if small) quark masses bring non-trivial consequences to the phase structure of QCD. Are deconfinement and chiral transition closely related? Do they happen at the same T? Several effective approaches available, but physics still unclear. (author)
Mirror fermions in chiral gauge theories
International Nuclear Information System (INIS)
Montvay, I.
1992-06-01
Mirror fermions appear naturally in lattice formulations of the standard model. The phenomenological limits on their existence and discovery limits at future colliders are discussed. After an introduction of lattice actions for chiral Yukawa-models, a recent numerical simulation is presented. In particular, the emerging phase structures and features of the allowed region in renormalized couplings are discussed. (orig.)
n+p→d+γ in effective field theory
International Nuclear Information System (INIS)
Savage, Martin J.; Scaldeferri, Kevin A.; Wise, Mark B.
1999-01-01
The radiative capture process n+p→d+γ provides clear evidence for meson exchange currents in nuclear physics. We compute this process at low energies using a recently developed power counting for the effective field theory that describes nucleon-nucleon interactions. The leading order contribution to this process comes from the photon coupling to the nucleon magnetic moments. At subleading order there are other contributions. Among these are graphs where the photon couples directly to pions, i.e. meson exchange currents. These diagrams are divergent and require the presence of a local four-nucleon-one-photon counterterm. The coefficient of this operator is determined by the measured cross section, σ expt = 334.2±0.5 mb, for incident neutrons with speed vertical bar ν vertical bar = 2200 m/s
Usefulness of effective field theory for boosted Higgs production
Energy Technology Data Exchange (ETDEWEB)
Dawson, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Lewis, I. M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Zeng, Mao [Stony Brook Univ., Stony Brook, NY (United States)
2015-04-07
The Higgs + jet channel at the LHC is sensitive to the effects of new physics both in the total rate and in the transverse momentum distribution at high _{pT}. We examine the production process using an effective field theory (EFT) language and discussing the possibility of determining the nature of the underlying high-scale physics from boosted Higgs production. The effects of heavy color triplet scalars and top partner fermions with TeV scale masses are considered as examples and Higgs-gluon couplings of dimension-5 and dimension-7 are included in the EFT. As a byproduct of our study, we examine the region of validity of the EFT. Dimension-7 contributions in realistic new physics models give effects in the high _{pT} tail of the Higgs signal which are so tiny that they are likely to be unobservable.
Dark matter effective field theory scattering in direct detection experiments
Energy Technology Data Exchange (ETDEWEB)
Schneck, K.; Cabrera, B.; Cerdeño, D. G.; Mandic, V.; Rogers, H. E.; Agnese, R.; Anderson, A. J.; Asai, M.; Balakishiyeva, D.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Billard, J.; Borgland, A.; Brandt, D.; Brink, P. L.; Bunker, R.; Caldwell, D. O.; Calkins, R.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Godfrey, G. L.; Golwala, S. R.; Hall, J.; Harris, H. R.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jardin, D. M.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kennedy, A.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, P.; Mahapatra, R.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Morales Mendoza, J. D.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Ricci, Y.; Roberts, A.; Saab, T.; Sadoulet, B.; Sander, J.; Schnee, R. W.; Scorza, S.; Serfass, B.; Shank, B.; Speller, D.; Toback, D.; Upadhyayula, S.; Villano, A. N.; Welliver, B.; Wilson, J. S.; Wright, D. H.; Yang, X.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.
2015-05-18
We examine the consequences of the effective field theory (EFT) of dark matter–nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.
Electric dipole moments of light nuclei in effective field theory
Energy Technology Data Exchange (ETDEWEB)
Bsaisou, Jan; Liebig, Susanna; Minossi, David [Institut fuer Kernphysik, Forschungszentrum Juelich (Germany); Juelich Center for Hadron Physics, Forschungszentrum Juelich (Germany); Hanhart, Christoph; Nogga, Andreas; Vries, Jordy de; Wirzba, Andreas [Institut fuer Kernphysik, Forschungszentrum Juelich (Germany); Juelich Center for Hadron Physics, Forschungszentrum Juelich (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich (Germany); JARA - Forces and Matter Experiments, Forschungszentrum Juelich (Germany); Meissner, UlfG. [Institut fuer Kernphysik, Forschungszentrum Juelich (Germany); Juelich Center for Hadron Physics, Forschungszentrum Juelich (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich (Germany); JARA - Forces and Matter Experiments, Forschungszentrum Juelich (Germany); Helmholtz-Institut fuer Strahlen und Kernphysik, Universitaet Bonn (Germany)
2014-07-01
Electric dipole moments (EDMs) break parity (P) and time-reversal (T) symmetry and thus, by the CPT-theorem, CP-symmetry. Once measured, they will be unambiguous signs of new physics since CP-violation from the standard mechanism predicts EDMs that are experimentally inaccessible in the foreseeable future. We calculate within the framework of effective field theory the two-nucleon contributions to the EDMs of the deuteron, helion, and triton induced by P- and T-violating terms that arise from the QCD θ-term or dimension-6 sources of physics beyond the Standard Model (SM). We demonstrate what insights into physics beyond the SM can be gained from a suitable combination of measurements and, if needed, supplementary lattice QCD calculations.
The Gaussian streaming model and convolution Lagrangian effective field theory
Energy Technology Data Exchange (ETDEWEB)
Vlah, Zvonimir [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, Stanford, CA 94306 (United States); Castorina, Emanuele; White, Martin, E-mail: zvlah@stanford.edu, E-mail: ecastorina@berkeley.edu, E-mail: mwhite@berkeley.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States)
2016-12-01
We update the ingredients of the Gaussian streaming model (GSM) for the redshift-space clustering of biased tracers using the techniques of Lagrangian perturbation theory, effective field theory (EFT) and a generalized Lagrangian bias expansion. After relating the GSM to the cumulant expansion, we present new results for the real-space correlation function, mean pairwise velocity and pairwise velocity dispersion including counter terms from EFT and bias terms through third order in the linear density, its leading derivatives and its shear up to second order. We discuss the connection to the Gaussian peaks formalism. We compare the ingredients of the GSM to a suite of large N-body simulations, and show the performance of the theory on the low order multipoles of the redshift-space correlation function and power spectrum. We highlight the importance of a general biasing scheme, which we find to be as important as higher-order corrections due to non-linear evolution for the halos we consider on the scales of interest to us.
Information loss in effective field theory: Entanglement and thermal entropies
Boyanovsky, Daniel
2018-03-01
Integrating out high energy degrees of freedom to yield a low energy effective field theory leads to a loss of information with a concomitant increase in entropy. We obtain the effective field theory of a light scalar field interacting with heavy fields after tracing out the heavy degrees of freedom from the time evolved density matrix. The initial density matrix describes the light field in its ground state and the heavy fields in equilibrium at a common temperature T . For T =0 , we obtain the reduced density matrix in a perturbative expansion; it reveals an emergent mixed state as a consequence of the entanglement between light and heavy fields. We obtain the effective action that determines the time evolution of the reduced density matrix for the light field in a nonperturbative Dyson resummation of one-loop correlations of the heavy fields. The Von-Neumann entanglement entropy associated with the reduced density matrix is obtained for the nonresonant and resonant cases in the asymptotic long time limit. In the nonresonant case the reduced density matrix displays an incipient thermalization albeit with a wave-vector, time and coupling dependent effective temperature as a consequence of memory of initial conditions. The entanglement entropy is time independent and is the thermal entropy for this effective, nonequilibrium temperature. In the resonant case the light field fully thermalizes with the heavy fields, the reduced density matrix loses memory of the initial conditions and the entanglement entropy becomes the thermal entropy of the light field. We discuss the relation between the entanglement entropy ultraviolet divergences and renormalization.
International Nuclear Information System (INIS)
Lyubovitskij, V.E.; Gutsche, Th.; Faessler, Amand; Mau, R. Vinh
2002-01-01
We apply the perturbative chiral quark model to the study of the low-energy πN interaction. Using an effective chiral Lagrangian we reproduce the Weinberg-Tomozawa result for the S-wave πN scattering lengths. After inclusion of the photon field we give predictions for the electromagnetic O(p 2 ) low-energy couplings of the chiral perturbation theory effective Lagrangian that define the electromagnetic mass shifts of nucleons and first-order (e 2 ) radiative corrections to the πN scattering amplitude. Finally, we estimate the leading isospin-breaking correction to the strong energy shift of the π - p atom in the 1s state, which is relevant for the experiment 'pionic hydrogen' at PSI
Anomaly-free chiral theories in six dimensions
International Nuclear Information System (INIS)
Green, M.B.; Schwarz, J.H.; West, P.C.
1985-01-01
The coupled N = 1 Yang-Mills plus supergravity theory in ten dimensions can be made anomaly-free for SO(32) or E/sub 8/ X E/sub 8/. Only the case of SO(32) is known to correspond to a superstring theory, which is probably necessary for a fully consistent quantum theory. Anomaly-free chiral theories in lower dimensions can be obtained by considering nontrivial compactifications (involving nonzero background gauge fields) of the ten-dimensional theory that satisfy a topological consistency condition. This paper considers the compactification of four dimensions on the manifold K/sub 3/ without requiring that the equations of motion be satisfied. This leads to a large number of anomaly-free chiral supersymmetric six-dimensional theories, corresponding to various ways of embedding U(1) factors in SO(32) or E/sub 8/ X E/sub 8/
Effective field theory of thermal Casimir interactions between anisotropic particles.
Haussman, Robert C; Deserno, Markus
2014-06-01
We employ an effective field theory (EFT) approach to study thermal Casimir interactions between objects bound to a fluctuating fluid surface or interface dominated by surface tension, with a focus on the effects of particle anisotropy. The EFT prescription disentangles the constraints imposed by the particles' boundaries from the calculation of the interaction free energy by constructing an equivalent point particle description. The finite-size information is captured in a derivative expansion that encodes the particles' response to external fields. The coefficients of the expansion terms correspond to generalized tensorial polarizabilities and are found by matching the results of a linear response boundary value problem computed in both the full and effective theories. We demonstrate the versatility of the EFT approach by constructing the general effective Hamiltonian for a collection of particles of arbitrary shapes. Taking advantage of the conformal symmetry of the Hamiltonian, we discuss a straightforward conformal mapping procedure to systematically determine the polarizabilities and derive a complete description for elliptical particles. We compute the pairwise interaction energies to several orders for nonidentical ellipses as well as their leading-order triplet interactions and discuss the resulting preferred pair and multibody configurations. Furthermore, we elaborate on the complications that arise with pinned particle boundary conditions and show that the powerlike corrections expected from dimensional analysis are exponentially suppressed by the leading-order interaction energies.
Hamiltonian lattice studies of chiral meson field theories
International Nuclear Information System (INIS)
Chin, S.A.
1998-01-01
The latticization of the non-linear sigma model reduces a chiral meson field theory to an O(4) spin lattice system with quantum fluctuations. The result is an interesting marriage between quantum many-body theory and classical spin systems. By solving the resulting lattice Hamiltonian by Monte Carlo methods, the dynamics and thermodynamics of pions can be determined non-perturbatively. In a variational 16 3 lattice study, the ground state chiral phase transition is shown to be first order. Moreover, as the chiral phase transition is approached, the mass gap of pionic collective modes with quantum number of the ω vector meson drops toward zero. (Copyright (1998) World Scientific Publishing Co. Pte. Ltd)
Chiral plaquette polaron theory of cuprate superconductivity
Tahir-Kheli, Jamil; Goddard, William A., III
2007-07-01
Ab initio density functional calculations on explicitly doped La2-xSrxCuO4 find that doping creates localized holes in out-of-plane orbitals. A model for cuprate superconductivity is developed based on the assumption that doping leads to the formation of holes on a four-site Cu plaquette composed of the out-of-plane A1 orbitals apical Opz , planar Cud3z2-r2 , and planar Opσ . This is in contrast to the assumption of hole doping into planar Cudx2-y2 and Opσ orbitals as in the t-J model. Allowing these holes to interact with the d9 spin background leads to chiral polarons with either a clockwise or anticlockwise charge current. When the polaron plaquettes percolate through the crystal at x≈0.05 for La2-xSrxCuO4 , a Cudx2-y2 and planar Opσ band is formed. The computed percolation doping of x≈0.05 equals the observed transition to the “metallic” and superconducting phase for La2-xSrxCuO4 . Spin exchange Coulomb repulsion with chiral polarons leads to d -wave superconducting pairing. The equivalent of the Debye energy in phonon superconductivity is the maximum energy separation between a chiral polaron and its time-reversed partner. This energy separation is on the order of the antiferromagnetic spin coupling energy, Jdd˜0.1eV , suggesting a higher critical temperature. An additive skew-scattering contribution to the Hall effect is induced by chiral polarons and leads to a temperature dependent Hall effect that fits the measured values for La2-xSrxCuO4 . The integrated imaginary susceptibility, observed by neutron spin scattering, satisfies ω/T scaling due to chirality and spin-flip scattering of polarons along with a uniform distribution of polaron energy splittings. The derived functional form is compatible with experiments. The static spin structure factor for chiral spin coupling of the polarons to the undoped antiferromagnetic Cud9 spins is computed for classical spins on large two-dimensional lattices and is found to be incommensurate with a
Lattice chiral gauge theories with finely-grained fermions
International Nuclear Information System (INIS)
Hernandez, P.; Sundrum, R.
1996-01-01
The importance of lattice gauge field interpolation for our recent non-perturbative formulation of chiral gauge theory is emphasized. We illustrate how the requisite properties are satisfied by our recent four-dimensional non-abelian interpolation scheme, by going through the simpler case of U(1) gauge fields in two dimensions. (orig.)
Finite volume at two-loops in chiral perturbation theory
International Nuclear Information System (INIS)
Bijnens, Johan; Rössler, Thomas
2015-01-01
We calculate the finite volume corrections to meson masses and decay constants in two and three flavour Chiral Perturbation Theory to two-loop order. The analytical results are compared with the existing result for the pion mass in two-flavour ChPT and the partial results for the other quantities. We present numerical results for all quantities.
Effective Field Theories and the Role of Consistency in Theory Choice
Wells, James D
2012-01-01
Promoting a theory with a finite number of terms into an effective field theory with an infinite number of terms worsens simplicity, predictability, falsifiability, and other attributes often favored in theory choice. However, the importance of these attributes pales in comparison with consistency, both observational and mathematical consistency, which propels the effective theory to be superior to its simpler truncated version of finite terms, whether that theory be renormalizable (e.g., Standard Model of particle physics) or nonrenormalizable (e.g., gravity). Some implications for the Large Hadron Collider and beyond are discussed, including comments on how directly acknowledging the preeminence of consistency can affect future theory work.
How to use the Standard Model effective field theory
Energy Technology Data Exchange (ETDEWEB)
Henning, Brian; Lu, Xiaochuan [Department of Physics, University of California, Berkeley,Berkeley, California 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,Berkeley, California 94720 (United States); Murayama, Hitoshi [Department of Physics, University of California, Berkeley,Berkeley, California 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,Berkeley, California 94720 (United States); Kavli Institute for the Physics and Mathematics of the Universe (WPI),Todai Institutes for Advanced Study, University of Tokyo,Kashiwa 277-8583 (Japan)
2016-01-05
We present a practical three-step procedure of using the Standard Model effective field theory (SM EFT) to connect ultraviolet (UV) models of new physics with weak scale precision observables. With this procedure, one can interpret precision measurements as constraints on a given UV model. We give a detailed explanation for calculating the effective action up to one-loop order in a manifestly gauge covariant fashion. This covariant derivative expansion method dramatically simplifies the process of matching a UV model with the SM EFT, and also makes available a universal formalism that is easy to use for a variety of UV models. A few general aspects of RG running effects and choosing operator bases are discussed. Finally, we provide mapping results between the bosonic sector of the SM EFT and a complete set of precision electroweak and Higgs observables to which present and near future experiments are sensitive. Many results and tools which should prove useful to those wishing to use the SM EFT are detailed in several appendices.
Toward an effective field theory approach to reheating
Özsoy, Ogan; Giblin, John T.; Nesbit, Eva; Şengör, Gizem; Watson, Scott
2017-12-01
We investigate whether effective field theory (EFT) approaches, which have been useful in examining inflation and dark energy, can also be used to establish a systematic approach to inflationary reheating. We consider two methods. First, we extend Weinberg's background EFT to the end of inflation and reheating. We establish when parametric resonance and decay of the inflaton occurs, but also find intrinsic theoretical limitations, which make it difficult to capture some reheating models. This motivates us to next consider Cheung et al.'s EFT approach, which instead focuses on perturbations and the symmetry breaking induced by the cosmological background. Adapting the latter approach to reheating implies some new and important differences compared to the EFT of inflation. In particular, there are new hierarchical scales, and we must account for inflaton oscillations during reheating, which lead to discrete symmetry breaking. Guided by the fundamental symmetries, we construct the EFT of reheating, and as an example of its usefulness we establish a new class of reheating models and the corresponding predictions for gravity wave observations. In this paper we primarily focus on the first stages of preheating. We conclude by discussing challenges for the approach and future directions. This paper builds on ideas first proposed in the paper [O. Ozsoy, G. Sengor, K. Sinha, and S. Watson, arXiv:1507.06651.].
Effective field theory, electric dipole moments and electroweak baryogenesis
International Nuclear Information System (INIS)
Balazs, Csaba; White, Graham; Yue, Jason
2017-01-01
Negative searches for permanent electric dipole moments (EDMs) heavily constrain models of baryogenesis utilising various higher dimensional charge and parity violating (CPV) operators. Using effective field theory, we create a model independent connection between these EDM constraints and the baryon asymmetry of the universe (BAU) produced during a strongly first order electroweak phase transition. The thermal aspects of the high scale physics driving the phase transition are paramaterised by the usual kink solution for the bubble wall profile. We find that operators involving derivatives of the Higgs field yield CPV contributions to the BAU containing derivatives of the Higgs vacuum expectation value (vev), while non-derivative operators lack such contributions. Consequently, derivative operators cannot be eliminated in terms of non-derivative operators (via the equations of motion) if one is agnostic to the new physics that leads to the phase transition. Thus, we re-classify the independent dimension six operators, restricting ourselves to third generation quarks, gauge bosons and the Higgs. Finally, we calculate the BAU (as a function of the bubble wall width and the cutoff) for a derivative and a non-derivative operator, and relate it to the EDM constraints.
Why does the effective field theory of inflation work?
Energy Technology Data Exchange (ETDEWEB)
Agarwal, Nishant [McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, Pittsburgh, PA, 15213 (United States); Ribeiro, Raquel H. [Department of Physics, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106 (United States); Holman, R., E-mail: nishanta@andrew.cmu.edu, E-mail: raquelhribeiro@case.edu, E-mail: rh4a@andrew.cmu.edu [Department of Physics, Carnegie Mellon University, Pittsburgh, PA, 15213 (United States)
2014-06-01
The effective field theory (EFT) of inflation has become the preferred method for computing cosmological correlation functions of the curvature fluctuation, ζ. It makes explicit use of the soft breaking of time diffeomorphisms by the inflationary background to organize the operators expansion in the action of the Goldstone mode π associated with this breaking. Despite its ascendancy, there is another method for calculating ζ correlators, involving the direct calculation of the so-called Horndeski action order by order in powers of ζ and its derivatives. The question we address in this work is whether or not the ζ correlators calculated in these seemingly different ways are in fact the same. The answer is that the actions to cubic order in either set of variables do indeed give rise to the same ζ bispectra, but that to make this equivalence manifest requires a careful understanding of the non-linear transformations relating π to ζ and how boundary terms in the actions are affected by imposing this relation. As a by product of our study we find that the calculations in the π language can be simplified considerably in a way that allows us to use only the linear part of the π−ζ relation simply by changing the coefficients of some of the operators in the EFT. We also note that a proper accounting of the boundary terms will be of the greatest importance when computing the bispectrum for more general initial states than the Bunch-Davies one.
Effective field theories in the large-N limit
International Nuclear Information System (INIS)
Weinberg, S.
1997-01-01
Various effective field theories in four dimensions are shown to have exact nontrivial solutions in the limit as the number N of fields of some type becomes large. These include extended versions of the U (N) Gross-Neveu model, the nonlinear O(N) σ model, and the CP N-1 model. Although these models are not renormalizable in the usual sense, the infinite number of coupling types allows a complete cancellation of infinities. These models provide qualitative predictions of the form of scattering amplitudes for arbitrary momenta, but because of the infinite number of free parameters, it is possible to derive quantitative predictions only in the limit of small momenta. For small momenta the large-N limit provides only a modest simplification, removing at most a finite number of diagrams to each order in momenta, except near phase transitions, where it reduces the infinite number of diagrams that contribute for low momenta to a finite number. copyright 1997 The American Physical Society
Neutrinoless double β decay and effective field theory
International Nuclear Information System (INIS)
Prezeau, G.; Ramsey-Musolf, M.; Vogel, Petr
2003-01-01
We analyze neutrinoless double β decay (0νββ decay) mediated by heavy particles from the standpoint of effective field theory. We show how symmetries of the 0νββ-decay quark operators arising in a given particle physics model determine the form of the corresponding effective, hadronic operators. We classify the latter according to their symmetry transformation properties as well as the order at which they appear in a derivative expansion. We apply this framework to several particle physics models, including R-parity violating supersymmetry (RPV SUSY) and the left-right symmetric model (LRSM) with mixing and a right-handed Majorana neutrino. We show that, in general, the pion exchange contributions to 0νββ decay dominate over the short-range four-nucleon operators. This confirms previously published RPV SUSY results and allows us to derive new constraints on the masses in the LRSM. In particular, we show how a nonzero mixing angle ζ in the left-right symmetry model produces a new potentially dominant contribution to 0νββ decay that substantially modifies previous limits on the masses of the right-handed neutrino and boson stemming from constraints from 0νββ decay and vacuum stability requirements
Effective field theory, electric dipole moments and electroweak baryogenesis
Energy Technology Data Exchange (ETDEWEB)
Balazs, Csaba; White, Graham [ARC Centre of Excellence for Particle Physics at the Terascale School of Physics and Astronomy,Monash University,Victoria 3800 (Australia); Yue, Jason [Department of Physics, National Taiwan Normal University,Taipei 116, Taiwan (China); ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics,The University of Sydney,NSW 2006 (Australia)
2017-03-07
Negative searches for permanent electric dipole moments (EDMs) heavily constrain models of baryogenesis utilising various higher dimensional charge and parity violating (CPV) operators. Using effective field theory, we create a model independent connection between these EDM constraints and the baryon asymmetry of the universe (BAU) produced during a strongly first order electroweak phase transition. The thermal aspects of the high scale physics driving the phase transition are paramaterised by the usual kink solution for the bubble wall profile. We find that operators involving derivatives of the Higgs field yield CPV contributions to the BAU containing derivatives of the Higgs vacuum expectation value (vev), while non-derivative operators lack such contributions. Consequently, derivative operators cannot be eliminated in terms of non-derivative operators (via the equations of motion) if one is agnostic to the new physics that leads to the phase transition. Thus, we re-classify the independent dimension six operators, restricting ourselves to third generation quarks, gauge bosons and the Higgs. Finally, we calculate the BAU (as a function of the bubble wall width and the cutoff) for a derivative and a non-derivative operator, and relate it to the EDM constraints.
Dissipative Effects in the Effective Field Theory of Inflation
Energy Technology Data Exchange (ETDEWEB)
Lopez Nacir, Diana; /Buenos Aires, CONICET /Buenos Aires U.; Porto, Rafael A.; /Princeton, Inst. Advanced Study /ISCAP, New York /Columbia U.; Senatore, Leonardo; /Stanford U., ITP /SLAC /KIPAC, Menlo Park; Zaldarriaga, Matias; /Princeton, Inst. Advanced Study
2012-09-14
We generalize the effective field theory of single clock inflation to include dissipative effects. Working in unitary gauge we couple a set of composite operators, {Omicron}{sub {mu}{nu}}..., in the effective action which is constrained solely by invariance under time-dependent spatial diffeomorphisms. We restrict ourselves to situations where the degrees of freedom responsible for dissipation do not contribute to the density perturbations at late time. The dynamics of the perturbations is then modified by the appearance of 'friction' and noise terms, and assuming certain locality properties for the Green's functions of these composite operators, we show that there is a regime characterized by a large friction term {gamma} >> H in which the {zeta}-correlators are dominated by the noise and the power spectrum can be significantly enhanced. We also compute the three point function <{zeta}{zeta}{zeta}> for a wide class of models and discuss under which circumstances large friction leads to an increased level of non-Gaussianities. In particular, under our assumptions, we show that strong dissipation together with the required non-linear realization of the symmetries implies |f{sub NL}| {approx} {gamma}/c{sub s}{sup 2} H >> 1. As a paradigmatic example we work out a variation of the 'trapped inflation' scenario with local response functions and perform the matching with our effective theory. A detection of the generic type of signatures that result from incorporating dissipative effects during inflation, as we describe here, would teach us about the dynamics of the early universe and also extend the parameter space of inflationary models.
Phenomenology of strongly coupled chiral gauge theories
International Nuclear Information System (INIS)
Bai, Yang; Berger, Joshua; Osborne, James; Stefanek, Ben A.
2016-01-01
A sector with QCD-like strong dynamics is common in models of non-standard physics. Such a model could be accessible in LHC searches if both confinement and big-quarks charged under the confining group are at the TeV scale. Big-quark masses at this scale can be explained if the new fermions are chiral under a new U(1) ′ gauge symmetry such that their bare masses are related to the U(1) ′ -breaking and new confinement scales. Here we present a study of a minimal GUT-motivated and gauge anomaly-free model with implications for the LHC Run 2 searches. We find that the first signatures of such models could appear as two gauge boson resonances. The chiral nature of the model could be confirmed by observation of a Z ′ γ resonance, where the Z ′ naturally has a large leptonic branching ratio because of its kinetic mixing with the hypercharge gauge boson.
Meson-baryon interactions in unitarized chiral perturbation theory
International Nuclear Information System (INIS)
Garcia Recio, G.; Nieves, J.; Ruiz Arriola, E.; Vicente Vacas, M.
2003-01-01
Meson-Baryon Interactions can be successfully described using both Chiral Symmetry and Unitarity. The s-wave meson-baryon scattering amplitude is analyzed in a Bethe-Salpeter coupled channel formalism incorporating Chiral Symmetry in the potential. Two body coupled channel unitarity is exactly preserved. The needed two particle irreducible matrix amplitude is taken from lowest order Chiral Perturbation Theory in a relativistic formalism. Off-shell behavior is parameterized in terms of low energy constants. The relation to the heavy baryon limit is discussed. The position of the complex poles in the second Riemann sheet of the scattering amplitude determine masses and widths baryonic resonances of the N(1535), N(1670), Λ(1405) and Λ(1670) resonances which compare well with accepted numbers
Global anomalies in chiral gauge theories on the lattice
International Nuclear Information System (INIS)
Baer, O.; Campos, I.
2000-01-01
We discuss the issue of global anomalies in chiral gauge theories on the lattice. In Luescher's approach, these obstructions make it impossible to define consistently a fermionic measure for the path integral. We show that an SU(2) theory has such a global anomaly if the Weyl fermion is in the fundamental representation. The anomaly in higher representations is also discussed. We finally show that this obstruction is the lattice analogue of the SU(2) anomaly first discovered by Witten. (orig.)
Chiral symmetry breaking in gauge theories from Reggeon diagram analysis
International Nuclear Information System (INIS)
White, A.R.
1991-01-01
It is argued that reggeon diagrams can be used to study dynamical properties of gauge theories containing a large number of massless fermions. SU(2) gauge theory is studied in detail and it is argued that there is a high energy solution which is analogous to the solution of the massless Schwinger model. A generalized winding-number condensate produces the massless pseudoscalar spectrum associated with chiral symmetry breaking and a ''trivial'' S-Matrix
Energy Technology Data Exchange (ETDEWEB)
Yao, De-Liang [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); Siemens, D. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Bernard, V. [Groupe de Physique Théorique, Institut de Physique Nucléaire, UMR 8606,CNRS, University Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex (France); Epelbaum, E. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Gasparyan, A.M. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); SSC RF ITEP, Bolshaya Cheremushkinskaya 25, 117218 Moscow (Russian Federation); Gegelia, J. [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); Tbilisi State University, 0186 Tbilisi (Georgia); Krebs, H. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Meißner, Ulf-G. [Helmholtz Institut für Strahlen- und Kernphysik andBethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany)
2016-05-05
We present the results of a third order calculation of the pion-nucleon scattering amplitude in a chiral effective field theory with pions, nucleons and delta resonances as explicit degrees of freedom. We work in a manifestly Lorentz invariant formulation of baryon chiral perturbation theory using dimensional regularization and the extended on-mass-shell renormalization scheme. In the delta resonance sector, the on mass-shell renormalization is realized as a complex-mass scheme. By fitting the low-energy constants of the effective Lagrangian to the S- and P-partial waves a satisfactory description of the phase shifts from the analysis of the Roy-Steiner equations is obtained. We predict the phase shifts for the D and F waves and compare them with the results of the analysis of the George Washington University group. The threshold parameters are calculated both in the delta-less and delta-full cases. Based on the determined low-energy constants, we discuss the pion-nucleon sigma term. Additionally, in order to determine the strangeness content of the nucleon, we calculate the octet baryon masses in the presence of decuplet resonances up to next-to-next-to-leading order in SU(3) baryon chiral perturbation theory. The octet baryon sigma terms are predicted as a byproduct of this calculation.
Effective field theory for quantum liquid in dwarf stars
Energy Technology Data Exchange (ETDEWEB)
Gabadadze, Gregory [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Rosen, Rachel A., E-mail: gg32@nyu.edu, E-mail: rarosen@physik.su.se [Oskar Klein Centre for Cosmoparticle Physics, Department of Physics, Stockholm University, AlbaNova, Roslagstullsbacken 21, SE - 106 91, Stockholm (Sweden)
2010-04-01
An effective field theory approach is used to describe quantum matter at greater-than-atomic but less-than-nuclear densities which are encountered in white dwarf stars. We focus on the density and temperature regime for which charged spin-0 nuclei form an interacting charged Bose-Einstein condensate, while the neutralizing electrons form a degenerate fermi gas. After a brief introductory review, we summarize distinctive properties of the charged condensate, such as a mass gap in the bosonic sector as well as gapless fermionic excitations. Charged impurities placed in the condensate are screened with great efficiency, greater than in an equivalent uncondensed plasma. We discuss a generalization of the Friedel potential which takes into account bosonic collective excitations in addition to the fermionic excitations. We argue that the charged condensate could exist in helium-core white dwarf stars and discuss the evolution of these dwarfs. Condensation would lead to a significantly faster rate of cooling than that of carbon- or oxygen-core dwarfs with crystallized cores. This prediction can be tested observationally: signatures of charged condensation may have already been seen in the recently discovered sequence of helium-core dwarfs in the nearby globular cluster NGC 6397. Sufficiently strong magnetic fields can penetrate the condensate within Abrikosov-like vortices. We find approximate analytic vortex solutions and calculate the values of the lower and upper critical magnetic fields at which vortices are formed and destroyed respectively. The lower critical field is within the range of fields observed in white dwarfs, but tends toward the higher end of this interval. This suggests that for a significant fraction of helium-core dwarfs, magnetic fields are entirely expelled within the core.
The effective field theory of inflation models with sharp features
International Nuclear Information System (INIS)
Bartolo, Nicola; Cannone, Dario; Matarrese, Sabino
2013-01-01
We describe models of single-field inflation with small and sharp step features in the potential (and sound speed) of the inflaton field, in the context of the Effective Field Theory of Inflation. This approach allows us to study the effects of features in the power-spectrum and in the bispectrum of curvature perturbations, from a model-independent point of view, by parametrizing the features directly with modified ''slow-roll'' parameters. We can obtain a self-consistent power-spectrum, together with enhanced non-Gaussianity, which grows with a quantity β that parametrizes the sharpness of the step. With this treatment it is straightforward to generalize and include features in other coefficients of the effective action of the inflaton field fluctuations. Our conclusion in this case is that, excluding extrinsic curvature terms, the only interesting effects at the level of the bispectrum could arise from features in the first slow-roll parameter ε or in the speed of sound c s . Finally, we derive an upper bound on the parameter β from the consistency of the perturbative expansion of the action for inflaton perturbations. This constraint can be used for an estimation of the signal-to-noise ratio, to show that the observable which is most sensitive to features is the power-spectrum. This conclusion would change if we consider the contemporary presence of a feature and a speed of sound c s < 1, as, in such a case, contributions from an oscillating folded configuration can potentially make the bispectrum the leading observable for feature models
Jet Definitions in Effective Field Theory and Decaying Dark Matter
Cheung, William Man Yin
2012-06-01
In this thesis jet production and cosmological constraints on decaying dark matter are studied. The powerful framework of effective field theory is applied in both cases to further our knowledge of particle physics. We first discuss how to apply the Soft Collinear Effective Theory (SCET) for calculating hadronic jet production rate. By applying SCET power counting, we develop a consistent approach to perform phase space integrations. This approach is then successfully applied to one-loop calculations with regard to a variety of jet algorithms. This allows us to study if the soft contribution can be factorized from the collinear ones. In particular we point out the connection between such factorization and the choice of ultraviolet regulator. We then further our study of the (exclusive) kT and C/A jet algorithms in SCET with the introduction of an additional regulator. Regularizing the virtualities and rapidities of graphs in SCET, we are able to write the next-to-leading-order dijet cross section as the product of separate hard, jet, and soft contributions. We show how to reproduce the Sudakov form factor to next-to-leading logarithmic accuracy previously calculated by the coherent branching formalism. Our resummed expression only depends on the renormalization group evolution of the hard function, rather than on that of the hard and jet functions as is usual in SCET. Finally we present a complete analysis of the cosmological constraints on decaying dark matter. For this, we have updated and extended previous analyses to include Lyman-alpha forest, large scale structure, and weak lensing observations. Astrophysical constraints are not considered in this thesis. The bounds on the lifetime of decaying dark matter are dominated by either the late-time integrated Sachs-Wolfe effect for the scenario with weak reionization, or CMB polarisation observations when there is significant reionization. For the respective scenarios, the lifetimes for decaying dark matter are
Heavy-light semileptonic decays in staggered chiral perturbation theory
Aubin, C.; Bernard, C.
2007-07-01
We calculate the form factors for the semileptonic decays of heavy-light pseudoscalar mesons in partially quenched staggered chiral perturbation theory (SχPT), working to leading order in 1/mQ, where mQ is the heavy-quark mass. We take the light meson in the final state to be a pseudoscalar corresponding to the exact chiral symmetry of staggered quarks. The treatment assumes the validity of the standard prescription for representing the staggered “fourth-root trick” within SχPT by insertions of factors of 1/4 for each sea-quark loop. Our calculation is based on an existing partially quenched continuum chiral perturbation theory calculation with degenerate sea quarks by Bećirević, Prelovsek, and Zupan, which we generalize to the staggered (and nondegenerate) case. As a byproduct, we obtain the continuum partially quenched results with nondegenerate sea quarks. We analyze the effects of nonleading chiral terms, and find a relation among the coefficients governing the analytic valence mass dependence at this order. Our results are useful in analyzing lattice computations of form factors B→π and D→K, when the light quarks are simulated with the staggered action.
Effective field theory and tunneling currents in the fractional quantum Hall effect
International Nuclear Information System (INIS)
Bieri, Samuel; Fröhlich, Jürg
2012-01-01
We review the construction of a low-energy effective field theory and its state space for “abelian” quantum Hall fluids. The scaling limit of the incompressible fluid is described by a Chern–Simons theory in 2+1 dimensions on a manifold with boundary. In such a field theory, gauge invariance implies the presence of anomalous chiral modes localized on the edge of the sample. We assume a simple boundary structure, i.e., the absence of a reconstructed edge. For the bulk, we consider a multiply connected planar geometry. We study tunneling processes between two boundary components of the fluid and calculate the tunneling current to lowest order in perturbation theory as a function of dc bias voltage. Particular attention is paid to the special cases when the edge modes propagate at the same speed, and when they exhibit two significantly distinct propagation speeds. We distinguish between two “geometries” of interference contours corresponding to the (electronic) Fabry–Perot and Mach–Zehnder interferometers, respectively. We find that the interference term in the current is absent when exactly one hole in the fluid corresponding to one of the two edge components involved in the tunneling processes lies inside the interference contour (i.e., in the case of a Mach–Zehnder interferometer). We analyze the dependence of the tunneling current on the state of the quantum Hall fluid and on the external magnetic flux through the sample. - Highlights: ► We review and extend on the field theoretic construction of the FQHE. ► We calculate tunneling currents between different edge components of a sample. ► We find an absence of interference terms in the currents for some sample geometries. ► No observable Aharonov–Bohm effect is found as the magnetic field is varied. ► Deformation of the edge leads to observable Aharonov–Bohm effect in the currents.
International Nuclear Information System (INIS)
Harada, Masayasu; Kikukawa, Yoshio; Yamawaki, Koichi
2003-01-01
This issue presents the important recent progress in both theoretical and phenomenological issues of strong coupling gauge theories, with/without supersymmetry and extra dimensions, etc. Emphasis in a placed on dynamical symmetry breaking with large anomalous dimensions governed by the dynamics near the nontrivial fixed point. Also presented are recent developments of the corresponding effective field theories. The 43 of the presented papers are indexed individually. (J.P.N)
SU(N) chiral gauge theories on the lattice
International Nuclear Information System (INIS)
Golterman, Maarten; Shamir, Yigal
2004-01-01
We extend the construction of lattice chiral gauge theories based on non-perturbative gauge fixing to the non-Abelian case. A key ingredient is that fermion doublers can be avoided at a novel type of critical point which is only accessible through gauge fixing, as we have shown before in the Abelian case. The new ingredient allowing us to deal with the non-Abelian case as well is the use of equivariant gauge fixing, which handles Gribov copies correctly, and avoids Neuberger's no-go theorem. We use this method in order to gauge fix the non-Abelian group (which we will take to be SU(N)) down to its maximal Abelian subgroup. Obtaining an undoubled, chiral fermion content requires us to gauge-fix also the remaining Abelian gauge symmetry. This modifies the equivariant Becchi-Rouet-Stora-Tyutin (BRST) identities, but their use in proving unitarity remains intact, as we show in perturbation theory. On the lattice, equivariant BRST symmetry as well as the Abelian gauge invariance are broken, and a judiciously chosen irrelevant term must be added to the lattice gauge-fixing action in order to have access to the desired critical point in the phase diagram. We argue that gauge invariance is restored in the continuum limit by adjusting a finite number of counter terms. We emphasize that weak-coupling perturbation theory applies at the critical point which defines the continuum limit of our lattice chiral gauge theory
On integration over Fermi fields in chiral and supersymmetric theories
International Nuclear Information System (INIS)
Vainshtein, A.I.; Zakharov, V.I.
1982-01-01
Chiral and supersymmetric theories are considered which cannot be formulated directly in Euclidean space or regularized by means of massive fields in a manifestly gauge invariant fashion. In case of so called real representations a simple recipe is proposed which allows for unambiguous evaluation of the fermionic determinant circumventing the difficulties mentioned. As application of the general technique the effective fermionic interactions induced by instantons of small size within simplest chiral and supesymmetric theories are calculated (SU(2) as the gauge group and one doublet of Weyl spinors or a triplet of Majorana spinors, respectively). In the latter case the effective Lagrangian violates explicitly invariance under supersymmetric transformations on the fermionic and vector fields defined in standard way [ru
Quark Fragmentation to Pions in an Effective Chiral Theory
Directory of Open Access Journals (Sweden)
Yazaki K.
2010-04-01
Full Text Available A description of fragmentation functions which satisfy the momentum and isospin sum rules is presented in an eﬀective chiral quark theory of QCD. We concentrate on the pion fragmentation function, taking into account cascade-like processes in a generalized jet-model approach. Numerical results obtained in this NJL-jet model are presented and compared to empirical parametrizations.
Three-nucleon scattering by using chiral perturbation theory potential
International Nuclear Information System (INIS)
Kamata, Hiroyuki
2003-01-01
Three-nucleon scattering problems are studied by using two-nucleon and three-nucleon potentials derived from chiral perturbation theory. The three-nucleon term is shown to appear in the effective potential of the rank of next-to-next-to-leading order (NNLO). New three-nucleon forces are taken into consideration in addition to the conventional Fujita-Miyazawa (FM) type three-nucleon potential. Two-nucleon potential of the chiral perturbation theory is as precise as the conventional ones in low energy region. The FM type three-nucleon force which explains Sagara discrepancy in high energy region is introduced automatically. Concerning the Ay puzzle, the results seems to behave as if the puzzle has been solved at the level of NLO, but at the NNLO (without three-nucleon force) level the result is similar to the cases of conventional potential indicating the need of three-nucleon force. In contrast to the FM type three-nucleon force, five free parameters exist in the new D and E type three-nucleon forces introduced by the NNLO, but they are reduced to two independent parameters by antisymmetrization, which are found to be sensitive to the coupling energy of tritons and to the nd scattering length (spin doublet state). Parameters determined from them cannot give satisfactory answer to the A y puzzle. It seems, however, too hasty to conclude that A y puzzle cannot be solved by the chiral perturbation theory. (S. Funahashi)
Chiral anomalies in higher dimensional supersymmetric theories
International Nuclear Information System (INIS)
Bonora, L.; Pasti, P.; Tonin, M.
1987-01-01
We derive explicit formulas for pure gauge anomalies in a SYM theory in 6D as well as in 10D. Each anomaly consists of two terms: a gauge cocycle and a cocycle of the superdiffeomorphisms. The derivation is based essentially on a remarkable property of supersymmetric theories which we call Weil triviality and is directly connected with the constraints. The analogous problem for Lorentz anomalies is stated in the same way. However, in general, there are difficulties concerning Weil triviality. We prove that for pure SUGRA in 6D as well as in 10D it is possible to prove Weil triviality and, consequently, to obtain explict expressions for pure Lorentz anomalies. However, as far as SUGRA coupled to SYM a la Chapline-Manton or a la Green-Schwarz is concerned, no self-evident solution is available. (orig.)
Argyres-Douglas theories, chiral algebras and wild Hitchin characters
Fredrickson, Laura; Pei, Du; Yan, Wenbin; Ye, Ke
2018-01-01
We use Coulomb branch indices of Argyres-Douglas theories on S 1 × L( k, 1) to quantize moduli spaces M_H of wild/irregular Hitchin systems. In particular, we obtain formulae for the "wild Hitchin characters" — the graded dimensions of the Hilbert spaces from quantization — for four infinite families of M_H , giving access to many interesting geometric and topological data of these moduli spaces. We observe that the wild Hitchin characters can always be written as a sum over fixed points in M_H under the U(1) Hitchin action, and a limit of them can be identified with matrix elements of the modular transform ST k S in certain two-dimensional chiral algebras. Although naturally fitting into the geometric Langlands program, the appearance of chiral algebras, which was known previously to be associated with Schur operators but not Coulomb branch operators, is somewhat surprising.
Nonlinear responses of chiral fluids from kinetic theory
Hidaka, Yoshimasa; Pu, Shi; Yang, Di-Lun
2018-01-01
The second-order nonlinear responses of inviscid chiral fluids near local equilibrium are investigated by applying the chiral kinetic theory (CKT) incorporating side-jump effects. It is shown that the local equilibrium distribution function can be nontrivially introduced in a comoving frame with respect to the fluid velocity when the quantum corrections in collisions are involved. For the study of anomalous transport, contributions from both quantum corrections in anomalous hydrodynamic equations of motion and those from the CKT and Wigner functions are considered under the relaxation-time (RT) approximation, which result in anomalous charge Hall currents propagating along the cross product of the background electric field and the temperature (or chemical-potential) gradient and of the temperature and chemical-potential gradients. On the other hand, the nonlinear quantum correction on the charge density vanishes in the classical RT approximation, which in fact satisfies the matching condition given by the anomalous equation obtained from the CKT.
Chiral perturbation theory for generalized parton distributions and baryon distribution amplitudes
Energy Technology Data Exchange (ETDEWEB)
Wein, Philipp
2016-05-06
In this thesis we apply low-energy effective field theory to the first moments of generalized parton distributions and to baryon distribution amplitudes, which are both highly relevant for the parametrization of the nonperturbative part in hard processes. These quantities yield complementary information on hadron structure, since the former treat hadrons as a whole and, thus, give information about the (angular) momentum carried by an entire parton species on average, while the latter parametrize the momentum distribution within an individual Fock state. By performing one-loop calculations within covariant baryon chiral perturbation theory, we obtain sensible parametrizations of the quark mass dependence that are ideally suited for the subsequent analysis of lattice QCD data.
On a Geometric Theory of Generalized Chiral Elasticity with Discontinuities
Directory of Open Access Journals (Sweden)
Suhendro I.
2008-01-01
Full Text Available In this work we develop, in a somewhat extensive manner, a geometric theory of chiral elasticity which in general is endowed with geometric discontinuities (sometimes referred to as defects. By itself, the present theory generalizes both Cosserat and void elasticity theories to a certain extent via geometrization as well as by taking intoaccount the action of the electromagnetic field, i.e., the incorporation of the electromagnetic field into the description of the so-called microspin (chirality also forms the underlying structure of this work. As we know, the description of the electromagnetic field as a unified phenomenon requires four-dimensional space-time rather than three-dimensional space as its background. For this reason we embed the three-dimensional material space in four-dimensional space-time. This way, the electromagnetic spin is coupled to the non-electromagnetic microspin, both being parts of the completemicrospin to be added to the macrospin in the full description of vorticity. In short, our objective is to generalize the existing continuum theories by especially describing microspin phenomena in a fully geometric way.
On a Geometric Theory of Generalized Chiral Elasticity with Discontinuities
Directory of Open Access Journals (Sweden)
Suhendro I.
2008-01-01
Full Text Available In this work we develop, in a somewhat extensive manner, a geometric theory of chiral elasticity which in general is endowed with geometric discontinuities (sometimes re- ferred to as defects . By itself, the present theory generalizes both Cosserat and void elasticity theories to a certain extent via geometrization as well as by taking into ac- count the action of the electromagnetic field, i.e., the incorporation of the electromag- netic field into the description of the so-called microspin ( chirality also forms the un- derlying structure of this work. As we know, the description of the electromagnetic field as a unified phenomenon requires four-dimensional space-time rather than three- dimensional space as its background. For this reason we embed the three-dimensional material space in four-dimensional space-time. This way, the electromagnetic spin is coupled to the non-electromagnetic microspin, both being parts of the complete mi- crospin to be added to the macrospin in the full description of vorticity. In short, our objective is to generalize the existing continuum theories by especially describing mi- crospin phenomena in a fully geometric way.
Neutral pion electroproduction off light nuclei in chiral perturbation theory
International Nuclear Information System (INIS)
Lenkewitz, Mark
2013-01-01
Threshold pion electroproduction on tri-nucleon systems is investigated in the framework of baryon Chiral Perturbation Theory (ChPT) at next-to-leading one-loop order O(q 4 ) in the chiral expansion. To this order in small momenta, the production operator is a sum of one- and two-nucleon terms. While the one-nucleon terms resemble the impulse approximation, the two-nucleon contributions represent corrections due to the relevant nuclear interactions, e.g. pion-exchange interactions, which prove to be dominant, and due to recoil effects of the participating nucleons, which appear to be negligible. We calculate the expectation value of the production operator using chiral wave functions in a three-dimensional approach without partial wave expansion. The resulting integrals are evaluated using adaptive Monte Carlo integration, the VEGAS algorithm of Lepage. We obtain results for the threshold production multipoles E 0+ and L 0+ on 3 He and 3 H and comment on the sensitivity to the fundamental neutron amplitude E 0+ π 0 n . 3 He appears to be a particularly promising target to extract information about the neutron amplitude. This idea is usually invoked for spin-dependent quantities since the 3 He wave function is strongly dominated by the principal S-state component which suggests that its spin is largely driven by the one of the neutron.
Effective field theories of baryons and mesons, or, what do quarks do?
International Nuclear Information System (INIS)
Keaton, G.L.
1995-01-01
This thesis is an attempt to understand the properties of the protons, pions and other hadrons in terms of their fundamental building blocks. In the first chapter the author reviews several of the approaches that have already been developed. The Nambu-Jona-Lasinio model offers the classic example of a derivation of meson properties from a quark Lagrangian. The chiral quark model encodes much of the intuition acquired in recent decades. The author also discusses the non-linear sigma model, the Skyrme model, and the constituent quark model, which is one of the oldest and most successful models. In the constituent quark model, the constituent quark appears to be different from the current quark that appears in the fundamental QCD Lagrangian. Recently it was proposed that the constituent quark is a topological soliton. In chapter 2 the author investigates this soliton, calculating its mass, radius, magnetic moment, color magnetic moment, and spin structure function. Within the approximations used, the magnetic moments and spin structure function cannot simultaneously be made to agree with the constituent quark model. In chapter 3 the author uses a different plan of attack. Rather than trying to model the constituents of the baryon, he begins with an effective field theory of baryons and mesons, with couplings and masses that are simply determined phenomenologically. Meson loop corrections to baryon axial currents are then computed in the 1/N expansion. It is already known that the one-loop corrections are suppressed by a factor 1/N; here it is shown that the two-loop corrections are suppressed by 1/N 2 . To leading order, these corrections are exactly the same as would be calculated in the constituent quark model. This method therefore offers a different approach to the constituent quark
Chiral gauged Wess-Zumino-Witten theories and coset models in conformal field theory
International Nuclear Information System (INIS)
Chung, S.; Tye, S.H.
1993-01-01
The Wess-Zumino-Witten (WZW) theory has a global symmetry denoted by G L direct-product G R . In the standard gauged WZW theory, vector gauge fields (i.e., with vector gauge couplings) are in the adjoint representation of the subgroup H contained-in G. In this paper, we show that, in the conformal limit in two dimensions, there is a gauged WZW theory where the gauge fields are chiral and belong to the subgroups H L and H R where H L and H R can be different groups. In the special case where H L =H R , the theory is equivalent to vector gauged WZW theory. For general groups H L and H R , an examination of the correlation functions (or more precisely, conformal blocks) shows that the chiral gauged WZW theory is equivalent to (G/H L ) L direct-product(G/H R ) R coset models in conformal field theory
Few remarks on chiral theories with sophisticated topology
International Nuclear Information System (INIS)
Golo, V.L.; Perelomov, A.M.
1978-01-01
Two classes of the two-dimensional Euclidean chiral field theoreties are singled out: 1) the field phi(x) takes the values in the compact Hermitiam symmetric space 2) the field phi(x) takes the values in an orbit of the adjoint representation of the comcompact Lie group. The theories have sophisticated topological and rich analytical structures. They are considered with the help of topological invariants (topological charges). Explicit formulae for the topological charges are indicated, and the lower bound extimate for the action is given
Low momentum penguin contributions in a chiral theory
International Nuclear Information System (INIS)
Eeg, J.O.
1985-11-01
It has been shown that penguin diagram contributions corresponding to u-quark loop momenta below a scale Λsub(x) approximately= 1 GeV are enhanced and could at least partly explain the ΔI=1/2 rule. Thus a previous calculation within the bag model is confirmed. The present caluculation is performed wihtin an effective chiral theory with pions and kaons coupled to quarks. It has been found that low momentum left-left loop contributions are important, while left-right contributions can be neglected
Nf=2 Lattice QCD and Chiral Perturbation Theory
International Nuclear Information System (INIS)
Scorzato, L.; Farchioni, F.; Hofmann, P.; Jansen, K.; Montvay, I.; Muenster, G.; Papinutto, M.; Scholz, E.E.; Shindler, A.; Ukita, N.; Urbach, C.; Wenger, U.; Wetzorke, I.
2006-01-01
By employing a twisted mass term, we compare recent results from lattice calculations of N f =2 dynamical Wilson fermions with Wilson Chiral Perturbation Theory (WChPT). The final goal is to determine some com- binations of Gasser-Leutwyler Low Energy Constants (LECs). A wide set of data with different lattice spacings (a ∼ 0.2 - 0.12 fm), different gauge actions (Wilson plaquette, DBW2) and different quark masses (down to the lowest pion mass allowed by lattice artifacts and including negative quark masses) provide a strong check of the applicability of WChPT in this regime and the scaling behaviours in the continuum limit
Einstein-aether as a quantum effective field theory
International Nuclear Information System (INIS)
Withers, Benjamin
2009-01-01
The possibility that Lorentz symmetry is violated in gravitational processes is relatively unconstrained by experiment, in stark contrast with the level of accuracy to which Lorentz symmetry has been confirmed in the matter sector. One model of Lorentz violation in the gravitational sector is Einstein-aether theory, in which Lorentz symmetry is broken by giving a vacuum expectation value to a dynamical vector field. In this paper, we analyse the effective theory for quantized gravitational and aether perturbations. We show that this theory possesses a controlled effective expansion within dimensional regularization, that is, for any process there are a finite number of Feynman diagrams which will contribute to a given order of accuracy. We find that there is no log running of the 2-derivative phenomenological parameters, justifying the use of experimental constraints for these parameters obtained over many orders of magnitude in energy scale. Given the stringent experimental bounds on 2-derivative Lorentz-violating operators, we estimate the size of matter Lorentz violation which arises due to loop effects. This amounts to an estimation of the natural size of coefficients for Lorentz-violating dimension-6 matter operators, which in turn can be used to obtain a new bound on the 2-derivative parameters of this theory.
Effective field theory approach to LHC Higgs data
Indian Academy of Sciences (India)
2016-08-23
Aug 23, 2016 ... pletely specify the theory up to 19 free parameters. The local ... distributions of particles produced in high-energy col- lisions ... magnetic and electric dipole moments, as well as .... generation space. ... rotation is needed to diagonalize the mass matrix. .... motion, integration by parts, and redefinition of fields.
The effective field theory of dark matter direct detection
Energy Technology Data Exchange (ETDEWEB)
Fitzpatrick, A. Liam; Haxton, Wick; Katz, Emanuel; Lubbers, Nicholas; Xu, Yiming
2013-02-01
We extend and explore the general non-relativistic effective theory of dark matter (DM) direct detection. We describe the basic non-relativistic building blocks of operators and discuss their symmetry properties, writing down all Galilean-invariant operators up to quadratic order in momentum transfer arising from exchange of particles of spin 1 or less. Any DM particle theory can be translated into the coefficients of an effective operator and any effective operator can be simply related to most general description of the nuclear response. We find several operators which lead to novel nuclear responses. These responses differ significantly from the standard minimal WIMP cases in their relative coupling strengths to various elements, changing how the results from different experiments should be compared against each other. Response functions are evaluated for common DM targets — F, Na, Ge, I, and Xe — using standard shell model techniques. We point out that each of the nuclear responses is familiar from past studies of semi-leptonic electroweak interactions, and thus potentially testable in weak interaction studies. We provide tables of the full set of required matrix elements at finite momentum transfer for a range of common elements, making a careful and fully model-independent analysis possible. Finally, we discuss embedding non-relativistic effective theory operators into UV models of dark matter.
Chiral trace relations in Ω-deformed N=2 theories
Energy Technology Data Exchange (ETDEWEB)
Beccaria, Matteo; Fachechi, Alberto; Macorini, Guido [Dipartimento di Matematica e Fisica Ennio De Giorgi,Università del Salento, Via Arnesano, 73100 Lecce (Italy); INFN - Sezione di LecceVia Arnesano, 73100 Lecce (Italy)
2017-05-04
We consider N=2SU(2) gauge theories in four dimensions (pure or mass deformed) and discuss the properties of the simplest chiral observables in the presence of a generic Ω-deformation. We compute them by equivariant localization and analyze the structure of the exact instanton corrections to the classical chiral ring relations. We predict exact relations valid at all instanton number among the traces 〈Trφ{sup n}〉, where φ is the scalar field in the gauge multiplet. In the Nekrasov-Shatashvili limit, such relations may be explained in terms of the available quantized Seiberg-Witten curves. Instead, the full two-parameter deformation enjoys novel features and the ring relations require non trivial additional derivative terms with respect to the modular parameter. Higher rank groups are briefly discussed emphasizing non-factorization of correlators due to the Ω-deformation. Finally, the structure of the deformed ring relations in the N=2{sup ⋆} theory is analyzed from the point of view of the Alday-Gaiotto-Tachikawa correspondence proving consistency as well as some interesting universality properties.
Finite density two color chiral perturbation theory revisited
Adhikari, Prabal; Beleznay, Soma B.; Mannarelli, Massimo
2018-06-01
We revisit two-color, two-flavor chiral perturbation theory at finite isospin and baryon density. We investigate the phase diagram obtained varying the isospin and the baryon chemical potentials, focusing on the phase transition occurring when the two chemical potentials are equal and exceed the pion mass (which is degenerate with the diquark mass). In this case, there is a change in the order parameter of the theory that does not lend itself to the standard picture of first order transitions. We explore this phase transition both within a Ginzburg-Landau framework valid in a limited parameter space and then by inspecting the full chiral Lagrangian in all the accessible parameter space. Across the phase transition between the two broken phases the order parameter becomes an SU(2) doublet, with the ground state fixing the expectation value of the sum of the magnitude squared of the pion and the diquark fields. Furthermore, we find that the Lagrangian at equal chemical potentials is invariant under global SU(2) transformations and construct the effective Lagrangian of the three Goldstone degrees of freedom by integrating out the radial fluctuations.
Minimal flavour violation an effective field theory approach
D'Ambrosio, G.; Isidori, G.; Strumia, A.
2002-01-01
We present a general analysis of extensions of the Standard Model which satisfy the criterion of Minimal Flavour Violation (MFV). We define this general framework by constructing a low-energy effective theory containing the Standard Model fields, with one or two Higgs doublets and, as the only source of SU(3)^5 flavour symmetry breaking, the background values of fields transforming under the flavour group as the ordinary Yukawa couplings. We analyse present bounds on the effective scale of dimension-six operators, which range between 1 and 10 TeV, with the most stringent constraints imposed by B -> X_s gamma. In this class of theories, it is possible to relate predictions for FCNC processes in B physics to those in K physics. We compare the sensitivity of various experimental searches in probing the hypothesis of MFV. Within the two-Higgs-doublet scenario, we develop a general procedure to obtain all tan(beta)-enhanced Higgs-mediated FCNC amplitudes, discussing in particular their impact in B -> l^+l^-, Delta...
Constraints on four dimensional effective field theories from string and F-theory
Energy Technology Data Exchange (ETDEWEB)
Baume, Florent
2017-06-21
This thesis is a study of string theory compactifications to four dimensions and the constraints the Effective Field theories must exhibit, exploring both the closed and open sectors. In the former case, we focus on axion monodromy scenarios and the impact the backreaction of the energy density induced by the vev of an axion has on its field excursions. For all the cases studied, we find that the backreaction is small up to a critical value, and the proper field distance is flux independent and at most logarithmic in the axion vev. We then move to the open sector, where we use the framework of F-theory. We first explore the relation between the spectra arising from F-theory GUTs and those coming from a decomposition of the adjoint of E{sub 8} to SU(5) x U(1){sup n}. We find that extending the latter spectrum with new SU(5)-singlet fields, and classifying all possible ways of breaking the Abelian factors, all the spectra coming from smooth elliptic fibration constructed in the literature fit in our classification. We then explore generic properties of the spectra arising when breaking SU(5) to the Standard Model gauge group while retaining some anomaly properties. We finish by a study of F-theory compactications on a singular elliptic fibration via Matrix Factorisation, and find the charged spectrum of two non-Abelian examples.
Constraints on four dimensional effective field theories from string and F-theory
International Nuclear Information System (INIS)
Baume, Florent
2017-01-01
This thesis is a study of string theory compactifications to four dimensions and the constraints the Effective Field theories must exhibit, exploring both the closed and open sectors. In the former case, we focus on axion monodromy scenarios and the impact the backreaction of the energy density induced by the vev of an axion has on its field excursions. For all the cases studied, we find that the backreaction is small up to a critical value, and the proper field distance is flux independent and at most logarithmic in the axion vev. We then move to the open sector, where we use the framework of F-theory. We first explore the relation between the spectra arising from F-theory GUTs and those coming from a decomposition of the adjoint of E 8 to SU(5) x U(1) n . We find that extending the latter spectrum with new SU(5)-singlet fields, and classifying all possible ways of breaking the Abelian factors, all the spectra coming from smooth elliptic fibration constructed in the literature fit in our classification. We then explore generic properties of the spectra arising when breaking SU(5) to the Standard Model gauge group while retaining some anomaly properties. We finish by a study of F-theory compactications on a singular elliptic fibration via Matrix Factorisation, and find the charged spectrum of two non-Abelian examples.
Effective field theory and unitarity in vector boson scattering
International Nuclear Information System (INIS)
Sekulla, Marco; Kilian, Wolfgang; Ohl, Thorsten; Reuter, Juergen
2016-10-01
Weak vector boson scattering at high energies will be one of the key measurements in current and upcoming LHC runs. It is most sensitive to any new physics associated with electroweak symmetry breaking. However, a conventional EFT analysis will fail at high energies. To address this problem, we present a parameter-free prescription valid for arbitrary perturbative and non-perturbative models: the T-matrix unitarization. We describe its implementation as an asymptotically consistent reference model matched to the low-energy effective theory. We show examples of typical observables of vector-boson scattering at the LHC in our unitarized framework. For many strongly-coupled models like composite Higgs models, dimension-8 operators might be actually the leading operators. In addition to those longitudinal and transversal dimension eight EFT operators, the effects of generic tensor and scalar resonances within simplified models are considered.
Effective field theories for superconducting systems with multiple Fermi surfaces
Energy Technology Data Exchange (ETDEWEB)
Braga, P.R., E-mail: pedro.rangel.braga@gmail.com [Departamento de Física Teórica, Instituto de Física, UERJ - Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier 524, 20550-013 Maracanã, Rio de Janeiro (Brazil); Granado, D.R., E-mail: diegorochagrana@uerj.br [Departamento de Física Teórica, Instituto de Física, UERJ - Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier 524, 20550-013 Maracanã, Rio de Janeiro (Brazil); Department of Physics and Astronomy, Ghent University, Krijgslaan 281-S9, 9000 Gent (Belgium); Guimaraes, M.S., E-mail: msguimaraes@uerj.br [Departamento de Física Teórica, Instituto de Física, UERJ - Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier 524, 20550-013 Maracanã, Rio de Janeiro (Brazil); Wotzasek, C., E-mail: clovis@if.ufrj.br [Instituto de Física, Universidade Federal do Rio de Janeiro, 21941-972, Rio de Janeiro (Brazil)
2016-11-15
In this work we investigate the description of superconducting systems with multiple Fermi surfaces. For the case of one Fermi surface we re-obtain the result that the superconductor is more precisely described as a topological state of matter. Studying the case of more than one Fermi surface, we obtain the effective theory describing a time reversal symmetric topological superconductor. These results are obtained by employing a general procedure to construct effective low energy actions describing states of electromagnetic systems interacting with charges and defects. The procedure consists in taking into account the proliferation or dilution of these charges and defects and its consequences for the low energy description of the electromagnetic response of the system. We find that the main ingredient entering the low energy characterization of the system with more than one Fermi surface is a non-conservation of the canonical supercurrent triggered by particular vortex configurations.
Effective Field Theories and Matching for Codimension-2 Branes
Burgess, C P; De Rham, C; Tasinato, G
2009-01-01
It is generic for the bulk fields sourced by branes having codimension two and higher to diverge at the brane position, much as does the Coulomb potential at the position of its source charge. This complicates finding the relation between brane properties and the bulk geometries they source. (These complications do not arise for codimension-1 sources, such as in RS geometries, because of the special properties unique to codimension one.) Understanding these relations is a prerequisite for phenomenological applications involving higher-codimension branes. Using codimension-2 branes in extra-dimensional scalar-tensor theories as an example, we identify the classical matching conditions that relate the near-brane asymptotic behaviour of bulk fields to the low-energy effective actions describing how space-filling codimension-2 branes interact with the surrounding extra-dimensional bulk. We do so by carefully regulating the near-brane divergences, and show how these may be renormalized in a general way. Among the ...
Effective field theory and weak non-leptonic interactions
International Nuclear Information System (INIS)
Miller, R.D.C.
1982-06-01
The techniques of Ovrut and Schnitzer (1981) are used to calculate the finite decoupling renormalisation constants resulting from heavy fermion decoupling in a non-abelian gauge theory exhibiting broken flavour symmetry. The results of this calculation are applied to realistic, massive QCD. The decoupling information may be absorbed into renormalisation group (R.G.) invariants. Working in the Landau gauge R.G. invariants are derived for the running coupling constants and running quark masses of effective QCD in the modified minimal subtraction scheme (for effective QCD with 3 to 8 flavours). This work is then applied to the major part of the thesis; a complete derivation of the effective weak non-leptonic sector of the standard model (SU(3)/sub c/ x SU(2) x U(1)), that is the construction of all effective weak non-leptonic Hamiltonians resulting from the standard model when all quark generations above the third along with the W and Z are explicitily decoupled. The form of decoupling in the work of Gilman and Wise (1979) has been adopted. The weak non-leptonic sector naturally decomposes into flavour changing and flavour conserving sectors relative to anomalous dimension calculations. The flavour changing sector further decomposes into penguin free and penguin generating sectors. Individual analyses of these three sectors are given. All sectors are analysed uniformly, based upon a standard model with n generations
Generalized polarizabilities of the nucleon in baryon chiral perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Lensky, Vadim [Johannes Gutenberg Universitaet Mainz, Institut fuer Kernphysik, Cluster of Excellence PRISMA, Mainz (Germany); Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Pascalutsa, Vladimir; Vanderhaeghen, Marc [Johannes Gutenberg Universitaet Mainz, Institut fuer Kernphysik, Cluster of Excellence PRISMA, Mainz (Germany)
2017-02-15
The nucleon generalized polarizabilities (GPs), probed in virtual Compton scattering (VCS), describe the spatial distribution of the polarization density in a nucleon. They are accessed experimentally via the process of electron-proton bremsstrahlung (ep → epγ) at electron-beam facilities, such as MIT-Bates, CEBAF (Jefferson Lab), and MAMI (Mainz). We present the calculation of the nucleon GPs and VCS observables at next-to-leading order in baryon chiral perturbation theory (BχPT), and confront the results with the empirical information. At this order our results are predictions, in the sense that all the parameters are well known from elsewhere. Within the relatively large uncertainties of our calculation we find good agreement with the experimental observations of VCS and the empirical extractions of the GPs. We find large discrepancies with previous chiral calculations - all done in heavy-baryon χPT (HBχPT) - and discuss the differences between BχPT and HBχPT responsible for these discrepancies. (orig.)
WIMP-nucleus scattering in chiral effective theory
Cirigliano, Vincenzo; Graesser, Michael L.; Ovanesyan, Grigory
2012-10-01
We discuss long-distance QCD corrections to the WIMP-nucleon(s) interactions in the framework of chiral effective theory. For scalar-mediated WIMP-quark interactions, we calculate all the next-to-leading-order corrections to the WIMP-nucleus elastic cross-section, including two-nucleon amplitudes and recoil-energy dependent shifts to the single-nucleon scalar form factors. As a consequence, the scalar-mediated WIMP-nucleus cross-section cannot be parameterized in terms of just two quantities, namely the neutron and proton scalar form factors at zero momentum transfer, but additional parameters appear, depending on the short-distance WIMP-quark interaction. Moreover, multiplicative factorization of the cross-section into particle, nuclear and astro-particle parts is violated. In practice, while the new effects are of the natural size expected by chiral power counting, they become very important in those regions of parameter space where the leading order WIMP-nucleus amplitude is suppressed, including the so-called "isospin-violating dark matter" regime. In these regions of parameter space we find order-of-magnitude corrections to the total scattering rates and qualitative changes to the shape of recoil spectra.
Anomalies of the entanglement entropy in chiral theories
Energy Technology Data Exchange (ETDEWEB)
Iqbal, Nabil [Institute for Theoretical Physics, University of Amsterdam,Science Park 904, Postbus 94485, 1090 GL Amsterdam (Netherlands); Wall, Aron C. [School of Natural Sciences, Institute for Advanced Study,Princeton, New Jersey 08540 (United States)
2016-10-20
We study entanglement entropy in theories with gravitational or mixed U(1) gauge-gravitational anomalies in two, four and six dimensions. In such theories there is an anomaly in the entanglement entropy: it depends on the choice of reference frame in which the theory is regulated. We discuss subtleties regarding regulators and entanglement entropies in anomalous theories. We then study the entanglement entropy of free chiral fermions and self-dual bosons and show that in sufficiently symmetric situations this entanglement anomaly comes from an imbalance in the flux of modes flowing through the boundary, controlled by familiar index theorems. In two and four dimensions we use anomalous Ward identities to find general expressions for the transformation of the entanglement entropy under a diffeomorphism. (In the case of a mixed anomaly there is an alternative presentation of the theory in which the entanglement entropy is not invariant under a U(1) gauge transformation. The free-field manifestation of this phenomenon involves a novel kind of fermion zero mode on a gravitational background with a twist in the normal bundle to the entangling surface.) We also study d-dimensional anomalous systems as the boundaries of d+1 dimensional gapped Hall phases. Here the full system is non-anomalous, but the boundary anomaly manifests itself in a change in the entanglement entropy when the boundary metric is sheared relative to the bulk.
Generalized uncertainty principle as a consequence of the effective field theory
Energy Technology Data Exchange (ETDEWEB)
Faizal, Mir, E-mail: mirfaizalmir@gmail.com [Irving K. Barber School of Arts and Sciences, University of British Columbia – Okanagan, Kelowna, British Columbia V1V 1V7 (Canada); Department of Physics and Astronomy, University of Lethbridge, Lethbridge, Alberta T1K 3M4 (Canada); Ali, Ahmed Farag, E-mail: ahmed.ali@fsc.bu.edu.eg [Department of Physics, Faculty of Science, Benha University, Benha, 13518 (Egypt); Netherlands Institute for Advanced Study, Korte Spinhuissteeg 3, 1012 CG Amsterdam (Netherlands); Nassar, Ali, E-mail: anassar@zewailcity.edu.eg [Department of Physics, Zewail City of Science and Technology, 12588, Giza (Egypt)
2017-02-10
We will demonstrate that the generalized uncertainty principle exists because of the derivative expansion in the effective field theories. This is because in the framework of the effective field theories, the minimum measurable length scale has to be integrated away to obtain the low energy effective action. We will analyze the deformation of a massive free scalar field theory by the generalized uncertainty principle, and demonstrate that the minimum measurable length scale corresponds to a second more massive scale in the theory, which has been integrated away. We will also analyze CFT operators dual to this deformed scalar field theory, and observe that scaling of the new CFT operators indicates that they are dual to this more massive scale in the theory. We will use holographic renormalization to explicitly calculate the renormalized boundary action with counter terms for this scalar field theory deformed by generalized uncertainty principle, and show that the generalized uncertainty principle contributes to the matter conformal anomaly.
Generalized uncertainty principle as a consequence of the effective field theory
Directory of Open Access Journals (Sweden)
Mir Faizal
2017-02-01
Full Text Available We will demonstrate that the generalized uncertainty principle exists because of the derivative expansion in the effective field theories. This is because in the framework of the effective field theories, the minimum measurable length scale has to be integrated away to obtain the low energy effective action. We will analyze the deformation of a massive free scalar field theory by the generalized uncertainty principle, and demonstrate that the minimum measurable length scale corresponds to a second more massive scale in the theory, which has been integrated away. We will also analyze CFT operators dual to this deformed scalar field theory, and observe that scaling of the new CFT operators indicates that they are dual to this more massive scale in the theory. We will use holographic renormalization to explicitly calculate the renormalized boundary action with counter terms for this scalar field theory deformed by generalized uncertainty principle, and show that the generalized uncertainty principle contributes to the matter conformal anomaly.
The Lamb shift in muonic hydrogen and the proton radius from effective field theories
Energy Technology Data Exchange (ETDEWEB)
Peset, Clara; Pineda, Antonio [Universitat Autonoma de Barcelona, Grup de Fisica Teorica, Dept. Fisica and IFAE, Bellaterra (Barcelona) (Spain)
2015-12-15
We comprehensively analyse the theoretical prediction for the Lamb shift in muonic hydrogen, and the associated determination of the proton radius. We use effective field theories. This allows us to relate the proton radius with well-defined objects in quantum field theory, eliminating unnecessary model dependence. The use of effective field theories also helps us to organize the computation so that we can clearly state the parametric accuracy of the result. In this paper we review all (and check several of) the contributions to the energy shift of order α{sup 5}, as well as those that scale like α{sup 6} x logarithms in the context of non-relativistic effective field theories of QED. (orig.)
SIMP model at NNLO in chiral perturbation theory
Hansen, Martin; Langæble, Kasper; Sannino, Francesco
2015-10-01
We investigate the phenomenological viability of a recently proposed class of composite dark matter models where the relic density is determined by 3 →2 number-changing processes in the dark sector. Here the pions of the strongly interacting field theory constitute the dark matter particles. By performing a consistent next-to-leading- and next-to-next-to-leading-order chiral perturbative investigation we demonstrate that the leading-order analysis cannot be used to draw conclusions about the viability of the model. We further show that higher-order corrections substantially increase the tension with phenomenological constraints challenging the viability of the simplest realization of the strongly interacting massive particle paradigm.
Revisiting the pion's scalar form factor in chiral perturbation theory
Juttner, Andreas
2012-01-01
The quark-connected and the quark-disconnected Wick contractions contributing to the pion's scalar form factor are computed in the two and in the three flavour chiral effective theory at next-to-leading order. While the quark-disconnected contribution to the form factor itself turns out to be power-counting suppressed its contribution to the scalar radius is of the same order of magnitude as the one of the quark-connected contribution. This result underlines that neglecting quark-disconnected contributions in simulations of lattice QCD can cause significant systematic effects. The technique used to derive these predictions can be applied to a large class of observables relevant for QCD-phenomenology.
International Nuclear Information System (INIS)
Saririan, K.
1997-05-01
In this thesis, the author presents some works in the direction of studying quantum effects in locally supersymmetric effective field theories that appear in the low energy limit of superstring theory. After reviewing the Kaehler covariant formulation of supergravity, he shows the calculation of the divergent one-loop contribution to the effective boson Lagrangian for supergravity, including the Yang-Mills sector and the helicity-odd operators that arise from integration over fermion fields. The only restriction is on the Yang-Mills kinetic energy normalization function, which is taken diagonal in gauge indices, as in models obtained from superstrings. He then presents the full result for the divergent one-loop contribution to the effective boson Lagrangian for supergravity coupled to chiral and Yang-Mills supermultiplets. He also considers the specific case of dilaton couplings in effective supergravity Lagrangians from superstrings, for which the one-loop result is considerably simplified. He studies gaugino condensation in the presence of an intermediate mass scale in the hidden sector. S-duality is imposed as an approximate symmetry of the effective supergravity theory. Furthermore, the author includes in the Kaehler potential the renormalization of the gauge coupling and the one-loop threshold corrections at the intermediate scale. It is shown that confinement is indeed achieved. Furthermore, a new running behavior of the dilaton arises which he attributes to S-duality. He also discusses the effects of the intermediate scale, and possible phenomenological implications of this model
Sigma Terms and Strangeness Contents of Baryon Octet in Modified Chiral Perturbation Theory
Institute of Scientific and Technical Information of China (English)
LI Xiao-Ya; L(U) Xiao-Fu
2006-01-01
In the frame work of chiral perturbation theory, a modified effective Lagrangian for meson-baryon system is constructed, where the SU(3) breaking effect for meson is considered. The difference between physical and chiral limit decay constants is taken into account. Calculated to one loop at O(p3), the sigma terms and strangeness contents of baryon octet are obtained.
1/N perturbation theory and quantum conservation laws for supersymmetrical chiral field. 2
International Nuclear Information System (INIS)
Aref'eva, I.Ya.; Krivoshchekov, V.K.; Medvedev, P.B.; Gosudarstvennyj Komitet Standartov Soveta Ministrov SSSR, Moscow; Gosudarstvennyj Komitet po Ispol'zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Teoreticheskoj i Ehksperimental'noj Fiziki)
1980-01-01
The renormalizability of the supersymmetric chiral model (supersymmetric nonlinear σ-model) is proved in the framework of the 1/N perturbation theory expansion proposed in the previous paper. The renormalizability proof is essentially based on the quantum supersymmetric chirality condition. The supersymmetric formulation of equations of motion is given. The first non-trivial quantum conservation laws are derived
Precision constraints on the top-quark effective field theory at future lepton colliders
Energy Technology Data Exchange (ETDEWEB)
Durieux, Gauthier
2017-08-15
We examine the constraints that future lepton colliders would impose on the effective field theory describing modifications of top-quark interactions beyond the standard model, through measurements of the e{sup +}e{sup -}→bW{sup +} anti bW{sup -} process. Statistically optimal observables are exploited to constrain simultaneously and efficiently all relevant operators. Their constraining power is sufficient for quadratic effective-field-theory contributions to have negligible impact on limits which are therefore basis independent. This is contrasted with the measurements of cross sections and forward-backward asymmetries. An overall measure of constraints strength, the global determinant parameter, is used to determine which run parameters impose the strongest restriction on the multidimensional effective-field-theory parameter space.
Precision constraints on the top-quark effective field theory at future lepton colliders
International Nuclear Information System (INIS)
Durieux, Gauthier
2017-08-01
We examine the constraints that future lepton colliders would impose on the effective field theory describing modifications of top-quark interactions beyond the standard model, through measurements of the e + e - →bW + anti bW - process. Statistically optimal observables are exploited to constrain simultaneously and efficiently all relevant operators. Their constraining power is sufficient for quadratic effective-field-theory contributions to have negligible impact on limits which are therefore basis independent. This is contrasted with the measurements of cross sections and forward-backward asymmetries. An overall measure of constraints strength, the global determinant parameter, is used to determine which run parameters impose the strongest restriction on the multidimensional effective-field-theory parameter space.
Laminar and Turbulent Dynamos in Chiral Magnetohydrodynamics. I. Theory
Energy Technology Data Exchange (ETDEWEB)
Rogachevskii, Igor; Kleeorin, Nathan [Department of Mechanical Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel); Ruchayskiy, Oleg [Discovery Center, Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Boyarsky, Alexey [Instituut-Lorentz for Theoretical Physics, Universiteit Leiden, Niels Bohrweg 2, 2333 CA Leiden (Netherlands); Fröhlich, Jürg [Institute of Theoretical Physics, ETH Hönggerberg, CH-8093 Zurich (Switzerland); Brandenburg, Axel; Schober, Jennifer, E-mail: gary@bgu.ac.il [Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden)
2017-09-10
The magnetohydrodynamic (MHD) description of plasmas with relativistic particles necessarily includes an additional new field, the chiral chemical potential associated with the axial charge (i.e., the number difference between right- and left-handed relativistic fermions). This chiral chemical potential gives rise to a contribution to the electric current density of the plasma ( chiral magnetic effect ). We present a self-consistent treatment of the chiral MHD equations , which include the back-reaction of the magnetic field on a chiral chemical potential and its interaction with the plasma velocity field. A number of novel phenomena are exhibited. First, we show that the chiral magnetic effect decreases the frequency of the Alfvén wave for incompressible flows, increases the frequencies of the Alfvén wave and of the fast magnetosonic wave for compressible flows, and decreases the frequency of the slow magnetosonic wave. Second, we show that, in addition to the well-known laminar chiral dynamo effect, which is not related to fluid motions, there is a dynamo caused by the joint action of velocity shear and chiral magnetic effect. In the presence of turbulence with vanishing mean kinetic helicity, the derived mean-field chiral MHD equations describe turbulent large-scale dynamos caused by the chiral alpha effect, which is dominant for large fluid and magnetic Reynolds numbers. The chiral alpha effect is due to an interaction of the chiral magnetic effect and fluctuations of the small-scale current produced by tangling magnetic fluctuations (which are generated by tangling of the large-scale magnetic field by sheared velocity fluctuations). These dynamo effects may have interesting consequences in the dynamics of the early universe, neutron stars, and the quark–gluon plasma.
Laminar and Turbulent Dynamos in Chiral Magnetohydrodynamics. I. Theory
International Nuclear Information System (INIS)
Rogachevskii, Igor; Kleeorin, Nathan; Ruchayskiy, Oleg; Boyarsky, Alexey; Fröhlich, Jürg; Brandenburg, Axel; Schober, Jennifer
2017-01-01
The magnetohydrodynamic (MHD) description of plasmas with relativistic particles necessarily includes an additional new field, the chiral chemical potential associated with the axial charge (i.e., the number difference between right- and left-handed relativistic fermions). This chiral chemical potential gives rise to a contribution to the electric current density of the plasma ( chiral magnetic effect ). We present a self-consistent treatment of the chiral MHD equations , which include the back-reaction of the magnetic field on a chiral chemical potential and its interaction with the plasma velocity field. A number of novel phenomena are exhibited. First, we show that the chiral magnetic effect decreases the frequency of the Alfvén wave for incompressible flows, increases the frequencies of the Alfvén wave and of the fast magnetosonic wave for compressible flows, and decreases the frequency of the slow magnetosonic wave. Second, we show that, in addition to the well-known laminar chiral dynamo effect, which is not related to fluid motions, there is a dynamo caused by the joint action of velocity shear and chiral magnetic effect. In the presence of turbulence with vanishing mean kinetic helicity, the derived mean-field chiral MHD equations describe turbulent large-scale dynamos caused by the chiral alpha effect, which is dominant for large fluid and magnetic Reynolds numbers. The chiral alpha effect is due to an interaction of the chiral magnetic effect and fluctuations of the small-scale current produced by tangling magnetic fluctuations (which are generated by tangling of the large-scale magnetic field by sheared velocity fluctuations). These dynamo effects may have interesting consequences in the dynamics of the early universe, neutron stars, and the quark–gluon plasma.
Extending Chiral Perturbation Theory with an Isosinglet Scalar
DEFF Research Database (Denmark)
Hansen, Martin; Langaeble, Kasper; Sannino, Francesco
2017-01-01
We augment the chiral Lagrangian by an isosinglet scalar and compute the one-loop radiative corrections to the pion mass and decay constant, as well as the scalar mass. The calculations are carried out for different patterns of chiral symmetry breaking of immediate relevance for phenomenology...
Two-dimensional field theory description of a disoriented chiral condensate
International Nuclear Information System (INIS)
Kogan, I.I.
1993-01-01
We consider the effective (1+1)-dimensional chiral theory describing fluctuations of the order parameter of the disoriented chiral condensate (DCC) which can be formed in the central rapidity region in relativistic nucleus-nucleus or nucleon-nucleon collisions at high energy. Using (1+1)-dimensional reduction of QCD at high energies and assuming spin polarization of the DDC one can find the Wess-Zumino-Novikov-Witten model at the level k=3 as the effective chiral theory for the one-dimensional DDC. Some possible phenomenological consequences are briefly discussed
Doublet channel neutron-deuteron scattering in leading order effective field theory
B. BlankleiderFlinders U.; J. Gegelia(INFN)
2015-01-01
The doublet channel neutron-deuteron scattering amplitude is calculated in leading order effective field theory (EFT). It is shown that this amplitude does not depend on a constant contact interaction three-body force. Satisfactory agreement with available data is obtained when only two-body forces are included.
Next-to-leading order effective field theory Lambda N -> NN potential in coordinate space
Czech Academy of Sciences Publication Activity Database
Peréz-Obiol Castaneda, Axel; Entem, D. R.; Julia-Diaz, B.; Parreno, A.
2016-01-01
Roč. 954, OCT (2016), s. 213-241 ISSN 0375-9474 R&D Projects: GA ČR(CZ) GA15-04301S Institutional support: RVO:61389005 Keywords : non-mesonic weak decay * effective field theory * hypernuclei Subject RIV: BE - Theoretical Physics Impact factor: 1.916, year: 2016
Three-body interactions in many-body effective field theory
International Nuclear Information System (INIS)
Furnstahl, R.J.
2004-01-01
This contribution is an advertisement for applying effective field theory (EFT) to many-body problems, including nuclei and cold atomic gases. Examples involving three-body interactions are used to illustrate how EFT's quantify and systematically eliminate model dependence, and how they make many-body calculations simpler and more powerful
On the Renormalization of the Effective Field Theory of Large Scale Structures
Pajer, Enrico; Zaldarriaga, Matias
2013-01-01
Standard perturbation theory (SPT) for large-scale matter inhomogeneities is unsatisfactory for at least three reasons: there is no clear expansion parameter since the density contrast is not small on all scales; it does not fully account for deviations at large scales from a perfect pressureless fluid induced by short-scale non-linearities; for generic initial conditions, loop corrections are UV-divergent, making predictions cutoff dependent and hence unphysical. The Effective Field Theory o...
Chiral symmetry breaking and nonperturbative scale anomaly in gauge field theories
International Nuclear Information System (INIS)
Miranskij, V.A.; Gusynin, V.P.
1987-01-01
The nonperturbative dynamics of chiral and scale symmetry breaking in asymtotically free and non-asymptotically free (with an ultraviolet stable fixed point) vector-like gauge theories is investigated. In the two-loop approximation analytical expressions for the chiral and gluon condensates are obtained. The hypothesis about a soft behaviour at small distances of composite operators in non-asymptotically free gauge theories with a fixed point is put forward and substantiated. It is shown that in these theories the form of the scale anomaly depends on the type of the phase in coupling constant to which it relates. A new dilaton effective lagrangian for glueball and chiral fields is suggested. The mass relation for the single scalar fermion-antifermion bound state is obtained. The important ingredient of this approach is a large (d≅ 2) dynamical dimension of composite chiral fields. The application of this approach to QCD and technicolour models is discussed
Abelian Duality, Confinement, and Chiral-Symmetry Breaking in a SU(2) QCD-Like Theory
International Nuclear Information System (INIS)
Uensal, Mithat
2008-01-01
We analyze the vacuum structure of SU(2) QCD with multiple massless adjoint representation fermions formulated on a small spatial S 1 xR 3 . The absence of thermal fluctuations, and the fact that quantum fluctuations favor the vacuum with unbroken center symmetry in a weakly coupled regime, renders the interesting dynamics of these theories analytically calculable. Confinement and the generation of the mass gap in the gluonic sector are shown analytically. In this regime, theory exhibits confinement without continuous chiral-symmetry breaking. However, a flavor singlet chiral condensate (which breaks a discrete chiral symmetry) persists at arbitrarily small S 1 . Under certain reasonable assumptions, we show that the theory exhibits a zero temperature chiral phase transition in the absence of any change in spatial center symmetry realizations
The MSSM without gluinos; an effective field theory for the stop sector
Energy Technology Data Exchange (ETDEWEB)
Aebischer, Jason; Greub, Christoph [University of Bern, Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, Bern (Switzerland); Crivellin, Andreas [Paul Scherrer Institut (PSI), Villigen (Switzerland); Yamada, Youichi [Tohoku University, Department of Physics, Sendai (Japan)
2017-11-15
In this article we study the MSSM with stops and Higgs scalars much lighter than gluinos and squarks of the first two generations. In this setup, one should use an effective field theory with partial supersymmetry in which the gluino and heavy squarks are integrated out in order to connect SUSY parameters (given at a high scale) to observables in the stop sector. In the construction of this effective theory, valid below the gluino mass scale, we take into account O(α{sub 3}) and O(Y{sub t,b}{sup 2}) effects and calculate the matching as well as the renormalization group evolution. As a result, the running of the parameters for the stop sector is modified with respect to the full MSSM and SUSY relations between parameters are broken. We show that for some couplings sizable numerical differences exist between the effective field theory approach and the naive calculation based on the MSSM running. (orig.)
Reformulation of the Hermitean 1-matrix model as an effective field theory
Energy Technology Data Exchange (ETDEWEB)
Klitz, Alexander
2009-07-15
The formal Hermitean 1-matrix model is shown to be equivalent to an effective field theory. The correlation functions and the free energy of the matrix model correspond directly to the correlation functions and the free energy of the effective field theory. The loop equation of the field theory coupling constants is stated. Despite its length, this loop equation is simpler than the loop equations in the matrix model formalism itself since it does not contain operator inversions in any sense, but consists instead only of derivative operators and simple projection operators. Therefore the solution of the loop equation could be given for an arbitrary number of cuts up to the fifth order in the topological expansion explicitly. Two different methods of obtaining the contributions to the free energy of the higher orders are given, one depending on an operator H and one not depending on it. (orig.)
On Yang--Mills Theories with Chiral Matter at Strong Coupling
Energy Technology Data Exchange (ETDEWEB)
Shifman, M.; /Minnesota U., Theor. Phys. Inst. /Saclay, SPhT; Unsal, Mithat; /SLAC /Stanford U., Phys. Dept.
2008-08-20
Strong coupling dynamics of Yang-Mills theories with chiral fermion content remained largely elusive despite much effort over the years. In this work, we propose a dynamical framework in which we can address non-perturbative properties of chiral, non-supersymmetric gauge theories, in particular, chiral quiver theories on S{sub 1} x R{sub 3}. Double-trace deformations are used to stabilize the center-symmetric vacuum. This allows one to smoothly connect smaller(S{sub 1}) to larger(S{sub 1}) physics (R{sub 4} is the limiting case) where the double-trace deformations are switched off. In particular, occurrence of the mass gap in the gauge sector and linear confinement due to bions are analytically demonstrated. We find the pattern of the chiral symmetry realization which depends on the structure of the ring operators, a novel class of topological excitations. The deformed chiral theory, unlike the undeformed one, satisfies volume independence down to arbitrarily small volumes (a working Eguchi-Kawai reduction) in the large N limit. This equivalence, may open new perspectives on strong coupling chiral gauge theories on R{sub 4}.
Study of open-charm 0{sup +} states in unitarized chiral effective theory with one-loop potentials
Energy Technology Data Exchange (ETDEWEB)
Du, Meng-Lin [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Guo, Feng-Kun [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China); University of Chinese Academy of Sciences, School of Physical Sciences, Beijing (China); Meissner, Ulf G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Forschungszentrum Juelich, Institute for Advanced Simulation, Institut fuer Kernphysik and Juelich Center for Hadron Physics (Germany); Yao, De-Liang [Forschungszentrum Juelich, Institute for Advanced Simulation, Institut fuer Kernphysik and Juelich Center for Hadron Physics (Germany); Instituto de Fisica Corpuscular (Centro mixto CSIC-UV), Institutos de Investigacion de Paterna, Valencia (Spain)
2017-11-15
Chiral potentials are derived for the interactions between Goldstone bosons and pseudo-scalar charmed mesons up to next-to-next-to-leading order in a covariant chiral effective field theory with explicit vector charmed-meson degrees of freedom. Using the extended-on-mass-shell scheme, we demonstrate that the ultraviolet divergences and the so-called power counting breaking terms can be properly absorbed by the low-energy constants of the chiral Lagrangians. We calculate the scattering lengths by unitarizing the one-loop potentials and fit them to the data extracted from lattice QCD. The obtained results are compared to the ones without an explicit contribution of vector charmed mesons given previously. It is found that the difference is negligible for S-wave scattering in the threshold region. This validates the use of D*-less one-loop potentials in the study of the pertinent scattering lengths. We search for dynamically generated open-charm states with J{sup P} = 0{sup +} as poles of the S-matrix on various Riemann sheets. The trajectories of those poles for varying pion masses are presented as well. (orig.)
Unraveling the Structure of Hadrons with Effective Field Theories of QCD
International Nuclear Information System (INIS)
Iain Stewart
2004-01-01
Effective Field theory is a powerful framework based on controlled expansions for problems with a natural separation of energy scales. This technique is particularly important for QCD, the theory of strong interactions, due to the vast diversity of phenomena that it describes. Stewart and collaborators have invented a new class of effective theories that can be used in processes with energetic hadrons. These Soft-Collinear Effective Theories provide a unified framework for describing hadronic processes which involve hard probes or the release of a large amount of energy. Many interesting issues about hadronic physics can be addressed with the soft-collinear effective theory. Examples include the size and shape of hadronic form factors, the universality of hadronic distribution functions for a plethora of processes, and the importance of subleading corrections at intermediate energy scales. Effective field theories allow these issues to be addressed using only the underlying symmetries and scales in QCD. Understanding these issues also has a direct impact on other areas of physics, such as on devising clean methods for the measurement of CP violation in the decay of B-mesons. Current progress on the soft-collinear effective theory and related methods is discussed in this report
Energy Technology Data Exchange (ETDEWEB)
Degrande, Celine [CERN, Theory Division, Geneva 23 (Switzerland); Fuks, Benjamin [Sorbonne Universites, UPMC Univ. Paris 06, Paris (France); CNRS, Paris (France); Mawatari, Kentarou [Universite Grenoble-Alpes, Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France); Vrije Universiteit Brussel, Theoretische Natuurkunde and IIHE/ELEM, International Solvay Institutes, Brussels (Belgium); Mimasu, Ken [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom); Universite catholique de Louvain, Centre for Cosmology, Particle Physics and Phenomenology (CP3), Louvain-la-Neuve (Belgium); Sanz, Veronica [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom)
2017-04-15
We study the impact of dimension-six operators of the standard model effective field theory relevant for vector-boson fusion and associated Higgs boson production at the LHC. We present predictions at the next-to-leading order accuracy in QCD that include matching to parton showers and that rely on fully automated simulations. We show the importance of the subsequent reduction of the theoretical uncertainties in improving the possible discrimination between effective field theory and standard model results, and we demonstrate that the range of the Wilson coefficient values allowed by a global fit to LEP and LHC Run I data can be further constrained by LHC Run II future results. (orig.)
Rosetta: an operator basis translator for standard model effective field theory
Energy Technology Data Exchange (ETDEWEB)
Falkowski, Adam [Laboratoire de Physique Théorique, Bat. 210, Université Paris-Sud, 91405, Orsay (France); Fuks, Benjamin [Département Recherches Subatomiques, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg/CNRS-IN2P3, 23 rue du Loess, 67037, Strasbourg (France); Mawatari, Kentarou [Theoretische Natuurkunde and IIHE/ELEM, Vrije Universiteit Brussel, and International Solvay Institutes, Pleinlaan 2, 1050, Brussels (Belgium); Mimasu, Ken, E-mail: k.mimasu@sussex.ac.uk [Department of Physics and Astronomy, University of Sussex, BN1 9QH, Brighton (United Kingdom); Riva, Francesco [CERN, Theory Division, 1211, Geneva (Switzerland); Sanz, Verónica [Department of Physics and Astronomy, University of Sussex, BN1 9QH, Brighton (United Kingdom)
2015-12-10
We introduce Rosetta, a program allowing for the translation between different bases of effective field theory operators. We present the main functions of the program and provide an example of usage. One of the Lagrangians which Rosetta can translate into has been implemented into FeynRules, which allows Rosetta to be interfaced into various high-energy physics programs such as Monte Carlo event generators. In addition to popular bases choices, such as the Warsaw and Strongly Interacting Light Higgs bases already implemented in the program, we also detail how to add new operator bases into the Rosetta package. In this way, phenomenological studies using an effective field theory framework can be straightforwardly performed.
Rosetta: an operator basis translator for standard model effective field theory
Energy Technology Data Exchange (ETDEWEB)
Falkowski, Adam [Universite Paris-Sud, Laboratoire de Physique Theorique, Bat. 210, Orsay (France); Fuks, Benjamin [Universite de Strasbourg/CNRS-IN2P3, Departement Recherches Subatomiques, Institut Pluridisciplinaire Hubert Curien, Strasbourg (France); Mawatari, Kentarou [Theoretische Natuurkunde and IIHE/ELEM, Vrije Universiteit Brussel, and International Solvay Institutes, Brussels (Belgium); Mimasu, Ken; Sanz, Veronica [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom); Riva, Francesco [CERN, Theory Division, Geneva (Switzerland)
2015-12-15
We introduce Rosetta, a program allowing for the translation between different bases of effective field theory operators. We present the main functions of the program and provide an example of usage. One of the Lagrangians which Rosetta can translate into has been implemented into FeynRules, which allows Rosetta to be interfaced into various high-energy physics programs such as Monte Carlo event generators. In addition to popular bases choices, such as the Warsaw and Strongly Interacting Light Higgs bases already implemented in the program, we also detail how to add new operator bases into the Rosetta package. In this way, phenomenological studies using an effective field theory framework can be straightforwardly performed. (orig.)
International Nuclear Information System (INIS)
Cohen, T.D.
1998-04-01
The physics goals of the effective field theory program for nuclear phenomena are outlined. It is pointed out that there are multiple schemes for implementing EFT and it is presently not clear if any of these schemes is viable. Most of the applications of effective field theory ideas have been on nucleon-nucleon scattering. It is argued that this is little more than curve fitting and that other quantities need to be calculated to test the ideas. It is shown that EFT methods work well for certain bound state properties of the deuteron electric form factor. However, it is also shown that this success depends sensitively on the fact that the majority of the probability of the deuteron's wave function is beyond the range of the potential. This circumstance is special to the deuteron suggesting that it will be very difficult to achieve the same kinds of success for tightly bound nuclei
K0 → π0γγ decays in chiral perturbation theory
International Nuclear Information System (INIS)
Ecker, G.; Pich, A.; Rafael, E. de
1987-01-01
The decays K L,S → π 0 γγ are calculated within the framework of chiral perturbation theory. The amplitude for K L → π 0 γγ is found to be finite at the one-loop level yielding a branching ratio of 6.8 · 10 -7 . The decay spectra of both decays are very characteristic and provide good tests of the effective chiral symmetry realization of the Standard Model. (Author)
The epsilon regime of chiral perturbation theory with Wilson-type fermions
Energy Technology Data Exchange (ETDEWEB)
Jansen, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Shindler, A. [Liverpool Univ. (United Kingdom). Theoretical Physics Division
2009-11-15
In this proceeding contribution we report on the ongoing effort to simulate Wilson-type fermions in the so called epsilon regime of chiral perturbation theory (cPT).We present results for the chiral condensate and the pseudoscalar decay constant obtained with Wilson twisted mass fermions employing two lattice spacings, two different physical volumes and several quark masses. With this set of simulations we make a first attempt to estimate the systematic uncertainties. (orig.)
The epsilon regime of chiral perturbation theory with Wilson-type fermions
International Nuclear Information System (INIS)
Jansen, K.; Shindler, A.
2009-11-01
In this proceeding contribution we report on the ongoing effort to simulate Wilson-type fermions in the so called epsilon regime of chiral perturbation theory (cPT).We present results for the chiral condensate and the pseudoscalar decay constant obtained with Wilson twisted mass fermions employing two lattice spacings, two different physical volumes and several quark masses. With this set of simulations we make a first attempt to estimate the systematic uncertainties. (orig.)
DEFF Research Database (Denmark)
Codello, Alessandro; Jain, Rajeev Kumar
2017-01-01
Following our previous work wherein the leading order effective action was computed in the covariant effective field theory of gravity, here we specialize the effective action to the FRW spacetime and obtain the effective Friedmann equations. In particular, we focus our attention on studying...... expansion of the universe at the present epoch even in the absence of a cosmological constant. We briefly discuss some phenomenological consequences of our results....
Van der Waals Forces and Photon-Less Effective Field Theory
International Nuclear Information System (INIS)
Arriola, E.R.
2011-01-01
In the ultra-cold regime Van der Waals forces between neutral atoms can be represented by short range effective interactions. We show that universal low energy scaling features of the underlying vdW long range force stemming from two photon exchange impose restrictions on an Effective Field Theory without explicit photons. The role of naively redundant operators, relevant to the definition of three body forces, is also analyzed. (author)
An analytic approach to sunset diagrams in chiral perturbation theory: Theory and practice
Energy Technology Data Exchange (ETDEWEB)
Ananthanarayan, B.; Ghosh, Shayan [Indian Institute of Science, Centre for High Energy Physics, Karnataka (India); Bijnens, Johan [Lund University, Department of Astronomy and Theoretical Physics, Lund (Sweden); Hebbar, Aditya [Indian Institute of Science, Centre for High Energy Physics, Karnataka (India); University of Delaware, Department of Physics and Astronomy, Newark, DE (United States)
2016-12-15
We demonstrate the use of several code implementations of the Mellin-Barnes method available in the public domain to derive analytic expressions for the sunset diagrams that arise in the two-loop contribution to the pion mass and decay constant in three-flavoured chiral perturbation theory. We also provide results for all possible two mass configurations of the sunset integral, and derive a new one-dimensional integral representation for the one mass sunset integral with arbitrary external momentum. Thoroughly annotated Mathematica notebooks are provided as ancillary files in the Electronic Supplementary Material to this paper, which may serve as pedagogical supplements to the methods described in this paper. (orig.)
An analytic approach to sunset diagrams in chiral perturbation theory: Theory and practice
International Nuclear Information System (INIS)
Ananthanarayan, B.; Ghosh, Shayan; Bijnens, Johan; Hebbar, Aditya
2016-01-01
We demonstrate the use of several code implementations of the Mellin-Barnes method available in the public domain to derive analytic expressions for the sunset diagrams that arise in the two-loop contribution to the pion mass and decay constant in three-flavoured chiral perturbation theory. We also provide results for all possible two mass configurations of the sunset integral, and derive a new one-dimensional integral representation for the one mass sunset integral with arbitrary external momentum. Thoroughly annotated Mathematica notebooks are provided as ancillary files in the Electronic Supplementary Material to this paper, which may serve as pedagogical supplements to the methods described in this paper. (orig.)
The ``Folk Theorem'' on effective field theory: How does it fare in nuclear physics?
Rho, Mannque
2017-10-01
This is a brief history of what I consider as very important, some of which truly seminal, contributions made by young Korean nuclear theorists, mostly graduate students working on PhD thesis in 1990s and early 2000s, to nuclear effective field theory, nowadays heralded as the first-principle approach to nuclear physics. The theoretical framework employed is an effective field theory anchored on a single scale-invariant hidden local symmetric Lagrangian constructed in the spirit of Weinberg's "Folk Theorem" on effective field theory. The problems addressed are the high-precision calculations on the thermal np capture, the solar pp fusion process, the solar hep process — John Bahcall's challenge to nuclear theorists — and the quenching of g A in giant Gamow-Teller resonances and the whopping enhancement of first-forbidden beta transitions relevant in astrophysical processes. Extending adventurously the strategy to a wild uncharted domain in which a systematic implementation of the "theorem" is far from obvious, the same effective Lagrangian is applied to the structure of compact stars. A surprising, unexpected, result on the properties of massive stars, totally different from what has been obtained up to day in the literature, is predicted, such as the precocious onset of conformal sound velocity together with a hint for the possible emergence in dense matter of hidden symmetries such as scale symmetry and hidden local symmetry.
Chiral perturbation theory approach to hadronic weak amplitudes
International Nuclear Information System (INIS)
Rafael, E. de
1989-01-01
We are concerned with applications to the non-leptonic weak interactions in the sector of light quark flavors: u, d and s. Both strangeness changing ΔS=1 and ΔS=2 non-leptonic transitions can be described as weak perturbations to the strong effective chiral Lagrangian; the chiral structure of the weak effective Lagrangian being dictated by the transformation properties of the weak non-leptonic Hamiltonian of the Standard Model under global SU(3) Left xSU(3) Right rotations of the quark-fields. These lectures are organized as follows. Section 2 gives a review of the basic properties of chiral symmetry. Section 3 explains the effective chiral realization of the non-leptonic weak Hamiltonian of the Standard Model to lowest order in derivatives and masses. Section 4 deals with non-leptonic weak transitions in the presence of electromagnetism. Some recent applications to radiative kaon decays are reviewed and the effect of the so called electromagnetic penguin like diagrams is also discussed. Section 5 explains the basic ideas of the QCD-hadronic duality approach to the evaluation of coupling constants of the non-leptonic chiral weak Lagrangian. (orig./HSI)
Renormalization Group Equations of d=6 Operators in the Standard Model Effective Field Theory
CERN. Geneva
2015-01-01
The one-loop renormalization group equations for the Standard Model (SM) Effective Field Theory (EFT) including dimension-six operators are calculated. The complete 2499 × 2499 one-loop anomalous dimension matrix of the d=6 Lagrangian is obtained, as well as the contribution of d=6 operators to the running of the parameters of the renormalizable SM Lagrangian. The presence of higher-dimension operators has implications for the flavor problem of the SM. An approximate holomorphy of the one-loop anomalous dimension matrix is found, even though the SM EFT is not a supersymmetric theory.
Numerical evidence of chiral magnetic effect in lattice gauge theory
International Nuclear Information System (INIS)
Buividovich, P. V.; Chernodub, M. N.; Luschevskaya, E. V.; Polikarpov, M. I.
2009-01-01
The chiral magnetic effect is the generation of electric current of quarks along an external magnetic field in the background of topologically nontrivial gluon fields. There is recent evidence that this effect is observed by the STAR Collaboration in heavy-ion collisions at the Relativistic Heavy Ion Collider. In our paper we study qualitative signatures of the chiral magnetic effect using quenched lattice simulations. We find indications that the electric current is indeed enhanced in the direction of the magnetic field both in equilibrium configurations of the quantum gluon fields and in a smooth gluon background with nonzero topological charge. In the confinement phase the magnetic field enhances the local fluctuations of both the electric charge and chiral charge densities. In the deconfinement phase the effects of the magnetic field become smaller, possibly due to thermal screening. Using a simple model of a fireball we obtain a good agreement between our data and experimental results of STAR Collaboration.
Study of X(3872) from effective field theory with pion-exchange interaction.
Wang, P; Wang, X G
2013-07-26
We study DD[over ¯]* (D*D[over ¯]) scattering in the framework of unitarized heavy meson chiral perturbation theory with pion exchange and a contact interaction. 3S1-3D1 mixing effects are taken into account. A loosely bound state X(3872), with the pole position being Mpole}=(3871.70-i0.39) MeV, is found. The result is not sensitive to the strength of the contact interaction. Our calculation provides a theoretical confirmation of the existence of the 1++ state X(3872). The light quark mass dependence of the pole position indicates it has a predominately DD[over ¯]* (D*D[over ¯]) molecular nature. When the π mass is larger than 142 MeV, the pole disappears, which makes impossible the lattice simulation of this state at large quark mass.
One-loop renormalization of Resonance Chiral Theory: scalar and pseudoscalar resonances
International Nuclear Information System (INIS)
Rosell, Ignasi; Ruiz-FemenIa, Pedro; Portoles, Jorge
2005-01-01
We consider the Resonance Chiral Theory with one multiplet of scalar and pseudoscalar resonances, up to bilinear couplings in the resonance fields, and evaluate its β-function at one-loop with the use of the background field method. Thus we also provide the full set of operators that renormalize the theory at one loop and render it finite
Effective field theory and integrability in two-dimensional Mott transition
International Nuclear Information System (INIS)
Bottesi, Federico L.; Zemba, Guillermo R.
2011-01-01
Highlights: → Mott transition in 2d lattice fermion model. → 3D integrability out of 2D. → Effective field theory for Mott transition in 2d. → Double Chern-Simons. → d-Density waves. - Abstract: We study the Mott transition in a two-dimensional lattice spinless fermion model with nearest neighbors density-density interactions. By means of a two-dimensional Jordan-Wigner transformation, the model is mapped onto the lattice XXZ spin model, which is shown to possess a quantum group symmetry as a consequence of a recently found solution of the Zamolodchikov tetrahedron equation. A projection (from three to two space-time dimensions) property of the solution is used to identify the symmetry of the model at the Mott critical point as U q (sl(2)-circumflex)xU q (sl(2)-circumflex), with deformation parameter q = -1. Based on this result, the low-energy effective field theory for the model is obtained and shown to be a lattice double Chern-Simons theory with coupling constant k = 1 (with the standard normalization). By further employing the effective filed theory methods, we show that the Mott transition that arises is of topological nature, with vortices in an antiferromagnetic array and matter currents characterized by a d-density wave order parameter. We also analyze the behavior of the system upon weak coupling, and conclude that it undergoes a quantum gas-liquid transition which belongs to the Ising universality class.
Theory of Magnetic Edge States in Chiral Graphene Nanoribbons
Capaz, Rodrigo; Yazyev, Oleg; Louie, Steven
2011-03-01
Using a model Hamiltonian approach including electron Coulomb interactions, we systematically investigate the electronic structure and magnetic properties of chiral graphene nanoribbons. We show that the presence of magnetic edge states is an intrinsic feature of any smooth graphene nanoribbons with chiral edges, and discover a number of structure-property relations. Specifically, we describe how the edge-state energy gap, zone-boundary edge-state energy splitting, and magnetic moment per edge length depend on the nanoribbon width and chiral angle. The role of environmental screening effects is also studied. Our results address a recent experimental observation of signatures of magnetic ordering at smooth edges of chiral graphene nanoribbons and provide an avenue towards tuning their properties via the structural and environmental degrees of freedom. This work was supported by National Science Foundation Grant No. DMR10-1006184, the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and the ONR MURI program. RBC acknowledges financial support from Brazilian agencies CNPq, FAPERJ and INCT-Nanomateriais de Carbono.
Complexity growth in massive gravity theories, the effects of chirality, and more
Ghodrati, Mahdis
2017-11-01
To study the effect of parity violation on the rate of complexity growth, by using "complexity=action " conjecture, we find the complexity growth rates in different solutions of the chiral theory of topologically massive gravity (TMG) and parity-preserving theory of new massive gravity (NMG). Using the results, one can see that decreasing the parameter μ , which increases the effect of the Chern-Simons term and increases chirality, would increase the rate of growth of complexity. Also one can observe a stronger correlation between complexity growth and temperature rather than complexity growth and entropy. At the end we comment on the possible meaning of the deforming term of chiral Liouville action for the rate of complexity growth of warped conformal field theories in the tensor network renormalization picture.
Heavy baryon chiral perturbation theory and the spin 3/2 delta resonances
Energy Technology Data Exchange (ETDEWEB)
Kambor, J.
1996-12-31
Heavy baryon chiral perturbation theory is briefly reviewed, paying particular attention to the role of the spin 3/2 delta resonances. The concept of resonance saturation for the baryonic sector is critically discussed. Starting from a relativistic formulation of the pion-nucleon-delta system, the heavy baryon chiral Lagrangian including spin 3/2 resonances is constructed by means of a 1/m-expansion. The effective theory obtained admits a systematic expansion in terms of soft momenta, the pion mass M{sub {pi}} and the delta-nucleon mass difference {Delta}. (author). 22 refs.
Recent developments in chiral gauge theories: approach of infinitely many fermi fields
International Nuclear Information System (INIS)
Narayanan, R.
1994-01-01
I present the recent developments in a specific sub-field of chiral gauge theories on the lattice. This subfield pertains to the use of infinitely many fermi fields to describe a single chiral field. In this approach, both anomalous and anomaly free theories can be discussed in equal footing. It produces the correct anomaly in the continuum limit. It has the potential to describe fermion number violating processes in the presence of a gauge field background with non-trivial topological charge on a finite lattice. (orig.)
Some remarks on chiral symmetry in dense matter
International Nuclear Information System (INIS)
Kaellman, C.G.; Montonen, C.
1982-01-01
The restoration of chiral symmetry in quantum chromodynamics as the temperature T and the chemical potential vertical stroke μ vertical stroke are increased is discussed qualitatively and using effective field theories. The latter are shown not to give reliable quantitative estimates. It is argued that a dilute gas of instantons cannot be the main dynamical agent responsible for the breakdown of chiral symmetry. (orig.)
International Nuclear Information System (INIS)
Ziino, G.
1989-01-01
We assume a strictly invariant definition of the Dirac parity operator under fermion ↔ antifermion exchange. We see that the opposite-intrinsic-parity condition then requires two opposite-mass Dirac equations for the fermion and the antifermion. This leads us to introduce an asymptotically left-handed (fermion) and right-handed (antifermion) chiral field, as just an alternative basis in the internal space spanned by the new pair of charge-conjugate Dirac fields. Hence a dual intrinsic model of a spin - 1/2 massive fermion is drawn: it predicts the coexistence of two anticommuting general varieties of conserved charges, namely a scalar variety, responsible for parity-invariant phenomenology, plus a pseudoscalar one, responsible for chiral phenomenology. In this light, CP-symmetry is seen to be nothing but P-symmetry; and a spontaneous CP-violation mechanism is also derived, that should work in any single process occurring via both scalar-and pseudoscalar-charge interactions. We show, at last, that our scheme automatically yields Weyl's one for a merely left-handed neutrino and a merely right-handed antineutrino, further assigning them the special meaning of pure pseudoscalar-charge objects. Some general consequences as regards magnetic monopoles are briefly discussed too
Dark energy and modified gravity in the Effective Field Theory of Large-Scale Structure
Cusin, Giulia; Lewandowski, Matthew; Vernizzi, Filippo
2018-04-01
We develop an approach to compute observables beyond the linear regime of dark matter perturbations for general dark energy and modified gravity models. We do so by combining the Effective Field Theory of Dark Energy and Effective Field Theory of Large-Scale Structure approaches. In particular, we parametrize the linear and nonlinear effects of dark energy on dark matter clustering in terms of the Lagrangian terms introduced in a companion paper [1], focusing on Horndeski theories and assuming the quasi-static approximation. The Euler equation for dark matter is sourced, via the Newtonian potential, by new nonlinear vertices due to modified gravity and, as in the pure dark matter case, by the effects of short-scale physics in the form of the divergence of an effective stress tensor. The effective fluid introduces a counterterm in the solution to the matter continuity and Euler equations, which allows a controlled expansion of clustering statistics on mildly nonlinear scales. We use this setup to compute the one-loop dark-matter power spectrum.
Effective field theory of statistical anisotropies for primordial bispectrum and gravitational waves
Energy Technology Data Exchange (ETDEWEB)
Rostami, Tahereh; Karami, Asieh; Firouzjahi, Hassan, E-mail: t.rostami@ipm.ir, E-mail: karami@ipm.ir, E-mail: firouz@ipm.ir [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)
2017-06-01
We present the effective field theory studies of primordial statistical anisotropies in models of anisotropic inflation. The general action in unitary gauge is presented to calculate the leading interactions between the gauge field fluctuations, the curvature perturbations and the tensor perturbations. The anisotropies in scalar power spectrum and bispectrum are calculated and the dependence of these anisotropies to EFT couplings are presented. In addition, we calculate the statistical anisotropy in tensor power spectrum and the scalar-tensor cross correlation. Our EFT approach incorporates anisotropies generated in models with non-trivial speed for the gauge field fluctuations and sound speed for scalar perturbations such as in DBI inflation.
Zero-range effective field theory for resonant wino dark matter. Part III. Annihilation effects
Braaten, Eric; Johnson, Evan; Zhang, Hong
2018-01-01
Near a critical value of the wino mass where there is a zero-energy S-wave resonance at the neutral-wino-pair threshold, low-energy winos can be described by a zero-range effective field theory (ZREFT) in which the winos interact nonperturbatively through a contact interaction and through Coulomb interactions. The effects of wino-pair annihilation into electroweak gauge bosons are taken into account through the analytic continuation of the real parameters for the contact interaction to comple...
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.
MatchingTools: A Python library for symbolic effective field theory calculations
Criado, Juan C.
2018-06-01
MatchingTools is a Python library for doing symbolic calculations in effective field theory. It provides the tools to construct general models by defining their field content and their interaction Lagrangian. Once a model is given, the heavy particles can be integrated out at the tree level to obtain an effective Lagrangian in which only the light particles appear. After integration, some of the terms of the resulting Lagrangian might not be independent. MatchingTools contains functions for transforming these terms to rewrite them in terms of any chosen set of operators.
International Nuclear Information System (INIS)
Kinoshita, Takehiro; Fujiyama, Shinya; Idogaki, Toshihiro; Tokita, Masahiko
2009-01-01
The non-equilibrium phase transition in a ferromagnetic Ising model is investigated by use of a new type of effective field theory (EFT) which correctly accounts for all the single-site kinematic relations by differential operator technique. In the presence of a time dependent oscillating external field, with decrease of the temperature the system undergoes a dynamic phase transition, which is characterized by the period averaged magnetization Q, from a dynamically disordered state Q = 0 to the dynamically ordered state Q ≠ 0. The results of the dynamic phase transition point T c determined from the behavior of the dynamic magnetization and the Liapunov exponent provided by EFT are improved than that of the standard mean field theory (MFT), especially for the one dimensional lattice where the standard MFT gives incorrect result of T c = 0 even in the case of zero external field.
The matter power spectrum in redshift space using effective field theory
Fonseca de la Bella, Lucía; Regan, Donough; Seery, David; Hotchkiss, Shaun
2017-11-01
The use of Eulerian 'standard perturbation theory' to describe mass assembly in the early universe has traditionally been limited to modes with k lesssim 0.1 h/Mpc at z=0. At larger k the SPT power spectrum deviates from measurements made using N-body simulations. Recently, there has been progress in extending the reach of perturbation theory to larger k using ideas borrowed from effective field theory. We revisit the computation of the redshift-space matter power spectrum within this framework, including for the first time the full one-loop time dependence. We use a resummation scheme proposed by Vlah et al. to account for damping of baryonic acoustic oscillations due to large-scale random motions and show that this has a significant effect on the multipole power spectra. We renormalize by comparison to a suite of custom N-body simulations matching the MultiDark MDR1 cosmology. At z=0 and for scales k lesssim 0.4 h/Mpc we find that the EFT furnishes a description of the real-space power spectrum up to ~ 2%, for the l = 0 mode up to ~ 5%, and for the l = 2, 4 modes up to ~ 25%. We argue that, in the MDR1 cosmology, positivity of the l=0 mode gives a firm upper limit of k ≈ 0.74 h/Mpc for the validity of the one-loop EFT prediction in redshift space using only the lowest-order counterterm. We show that replacing the one-loop growth factors by their Einstein-de Sitter counterparts is a good approximation for the l=0 mode, but can induce deviations as large as 2% for the l=2, 4 modes. An accompanying software bundle, distributed under open source licenses, includes Mathematica notebooks describing the calculation, together with parallel pipelines capable of computing both the necessary one-loop SPT integrals and the effective field theory counterterms.
Chiral 2d theories from N=4 SYM with varying coupling
Energy Technology Data Exchange (ETDEWEB)
Lawrie, Craig [Institut für Theoretische Physik, Ruprecht-Karls-Universität,Philosophenweg 19, 69120 Heidelberg (Germany); Schäfer-Nameki, Sakura [Mathematical Institute, University of Oxford,Woodstock Road, Oxford, OX2 6GG (United Kingdom); Weigand, Timo [Institut für Theoretische Physik, Ruprecht-Karls-Universität,Philosophenweg 19, 69120 Heidelberg (Germany)
2017-04-19
We study 2d chiral theories arising from 4d N=4 Super-Yang Mills (SYM) with varying coupling τ. The 2d theory is obtained by dimensional reduction of N=4 SYM on a complex curve with a partial topological twist that accounts for the non-constant τ. The resulting 2d theories can preserve (0,n) with n=2,4,6,8 chiral supersymmetry, and have a natural realization in terms of strings from wrapped D3-branes in F-theory. We determine the twisted dimensional reduction, as well as the spectrum and anomaly polynomials of the resulting strings in various dimensions. We complement this by considering the dual M-theory configurations, which can either be realized in terms of M5-branes wrapped on complex surfaces, or M2-branes on curves that result in 1d supersymmetric quantum mechanics.
Ksub(lsub(4)) decay in the chiral quantum field theory
International Nuclear Information System (INIS)
Ebert, D.; Kreopalov, D.V.; Volkov, M.K.
1978-01-01
Form factors of Ksub(lsub(4))-decay are described in the framework of chiral quantum field theory. The axial form factors are calculated in the tree approximation which defines their main contribution. The vector form factor is calculated in the one-loop approximation. The results are in satisfactory agreement with the available experimental data
$β'_{IR}$ at an Infrared Fixed Point in Chiral Gauge Theories
DEFF Research Database (Denmark)
Ryttov, Thomas A.; Shrock, Robert
2018-01-01
We present scheme-independent calculations of the derivative of the beta function, denoted $\\beta'_{IR}$, at a conformally invariant infrared (IR) fixed point, in several asymptotically free chiral gauge theories, namely SO($4k+2$) with $2 \\le k \\le 4$ with respective numbers $N_f$ of fermions...
The width of the Δ-resonance at two loop order in baryon chiral perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Gegelia, Jambul, E-mail: j.gegelia@fz-juelich.de [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Tbilisi State University, 0186 Tbilisi, Georgia (United States); Meißner, Ulf-G., E-mail: meissner@hiskp.uni-bonn.de [Helmholtz Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Siemens, Dmitrij, E-mail: dmitrij.siemens@rub.de [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Yao, De-Liang, E-mail: d.yao@fz-juelich.de [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany)
2016-12-10
We calculate the width of the delta resonance at leading two-loop order in baryon chiral perturbation theory. This gives a correlation between the leading pion–nucleon–delta and pion–delta couplings, which is relevant for the analysis of pion–nucleon scattering and other processes.
Dynamical breakdown of chiral symmetry in vectorial theories: QED and QCD
International Nuclear Information System (INIS)
Garcia, J.C.M.
1987-01-01
Using a variational approach for the Effective Potential for composite operators we dicuss the dynamical breakdown of chiral symmetry in two vectorial theories: Quantum Electrodynamics (QED) and Quantum Chromodynamics (QCD). We study the energetic aspects of the problem calculating the Effective Potential with the asymptotic nonperturbative solutions of the Schwinger-Dyson equation for the fermion selfenergy. (author) [pt
Determination of low-energy constants of Wilson chiral perturbation theory
International Nuclear Information System (INIS)
Herdoiza, Gregorio; Univ. Autonoma de Madrid, Contoblanco; Univ. Autonoma de Madrid; Jansen, Karl; Univ. Cyprus, Nicosia; Michael, Chris; Ottnad, Konstantin; Urbach, Carsten; Univ. Bonn
2013-03-01
By matching Wilson twisted mass lattice QCD determinations of pseudoscalar meson masses to Wilson Chiral Perturbation Theory we determine the low-energy constants W 6 ' , W 8 ' and their linear combination c 2 . We explore the dependence of these low-energy constants on the choice of the lattice action and on the number of dynamical flavours.
Chiral spiral waveguides based on MMI crossings: theory and experiments
Cherchi, Matteo; Ylinen, Sami; Harjanne, Mikko; Kapulainen, Markku; Vehmas, Tapani; Aalto, Timo
2016-03-01
We introduce a novel type of chiral spiral waveguide where the usual waveguide crossings are replaced by 100:0 Multimode Interferometers (MMIs), i.e. 2x2 splitters that couple all the input light in the cross output port. Despite the topological equivalence with the standard configuration, we show how resorting to long MMIs has non-trivial advantages in terms of footprint and propagation length. An accurate analytic model is also introduced to show the impact of nonidealities on the spiral performances, including propagation loss and cross-talk. We have designed and fabricated three chiral spirals on our platform, based on 3 μm thick silicon strip waveguides with 0.13 dB/cm propagation loss, and 1.58 mm long MMIs. The fabricated spirals have 7, 13 and 49 loops respectively, corresponding to the effective lengths 6.6 cm, 12.5 cm and 47.9 cm. The proposed model is successfully applied to the experimental results, highlighting MMI extinction ratio of about 16.5 dB and MMI loss of about 0.08 dB, that are much worse compared to the simulated 50 dB extinction and 0.01 dB loss. This imposes an upper limit to the number of rounds, because light takes shortcuts through the bar MMI ports. Nevertheless, the novel chiral spiral waveguides outperform what is achievable in mainstream silicon photonics platforms based on submicron waveguides in terms of length and propagation losses, and they are promising candidates for the realization of integrated gyroscopes. They can be significantly further improved by replacing the MMIs with adiabatic 100:0 splitters, ensuring lower cross-talk and broader bandwidth.
Chiral symmetry and finite temperature effects in quantum theories
International Nuclear Information System (INIS)
Larsen, Aa.
1987-01-01
A computer simulation of the harmonic oscillator at finite temperature has been carried out, using the Monte Carlo Metropolis algorithm. Accurate results for the energy and fluctuations have been obtained, with special attention to the manifestation of the temperature effects. Varying the degree of symmetry breaking, the finite temperature behaviour of the asymmetric linear model in a linearized mean field approximation has been studied. In a study of the effects of chiral symmetry on baryon mass splittings, reasonable agreement with experiment has been obtained in a non-relativistic harmonic oscillator model
Random matrix theory and higher genus integrability: the quantum chiral Potts model
International Nuclear Information System (INIS)
Angles d'Auriac, J.Ch.; Maillard, J.M.; Viallet, C.M.
2002-01-01
We perform a random matrix theory (RMT) analysis of the quantum four-state chiral Potts chain for different sizes of the chain up to size L 8. Our analysis gives clear evidence of a Gaussian orthogonal ensemble (GOE) statistics, suggesting the existence of a generalized time-reversal invariance. Furthermore, a change from the (generic) GOE distribution to a Poisson distribution occurs when the integrability conditions are met. The chiral Potts model is known to correspond to a (star-triangle) integrability associated with curves of genus higher than zero or one. Therefore, the RMT analysis can also be seen as a detector of 'higher genus integrability'. (author)
Pion parameters in nuclear medium from chiral perturbation theory and virial expansion
International Nuclear Information System (INIS)
Mallik, S.; Sarkar, Sourav
2004-01-01
We consider two methods to find the effective parameters of the pion traversing a nuclear medium. One is the first order chiral perturbation theoretic evaluation of the pion pole contribution to the two-point function of the axial-vector current. The other is the exact, first order virial expansion of the pion self-energy. We find that, although the results of chiral perturbation theory are not valid at normal nuclear density, those from the virial expansion may be reliable at such density. The latter predicts both the mass shift and the in-medium decay width of the pion to be small, of about a few MeV
Even- and Odd-Parity Charmed Meson Masses in Heavy Hadron Chiral Perturbation Theory
Energy Technology Data Exchange (ETDEWEB)
Thomas Mehen; Roxanne Springer
2005-03-01
We derive mass formulae for the ground state, J{sup P} = 0{sup -} and 1{sup -}, and first excited even-parity, J{sup P} = 0{sup +} and 1{sup +}, charmed mesons including one loop chiral corrections and {Omicron}(1/m{sub c}) counterterms in heavy hadron chiral perturbation theory. We show a variety of fits to the current data. We find that certain parameter relations in the parity doubling model are not renormalized at one loop, providing a natural explanation for the equality of the hyperfine splittings of ground state and excited doublets.
ΔΔ intermediate state in 1S0NN scattering from effective field theory
International Nuclear Information System (INIS)
Savage, M.J.
1997-01-01
We examine the role of the ΔΔ intermediate state in NN scattering in the 1 S 0 channel. The computation is performed at lowest order in an effective-field theory involving local four-fermion operators and one-pion exchange using dimensional regularization with minimal subtraction (MS). As first discussed by Weinberg, in the theory with only nucleons, the large-scattering length in this channel requires a small scale for the local N 4 operators. When Δ close-quote s are included (but without pions) a large-scattering length can be obtained from operators with a scale √(2M N (M Δ -M N )), but fine-tuning is required. The coefficients of the contact terms involving the Δ fields are not uniquely determined but for reasonable values one finds that, in general, NN scattering computed in the theory with Δ close-quote s looks like that computed in the theory without Δ close-quote s. The leading effect of the Δ close-quote s is to change the coefficients of the four-nucleon contact terms between the theories with and without Δ close-quote s. Further, the decoupling of the Δ close-quote s in the limit of large mass and strong coupling is clearly demonstrated. When pions are included, the typical scale for the contact terms is ∼100MeV, both with and without Δ close-quote s and is not set by √(2M N (M Δ -M N )). For reasonable values of contact terms that reproduce the scattering length and effective range (at lowest order) the phase shift is not well reproduced over a larger momentum range as is found in the theory without Δ close-quote s at lowest order. copyright 1997 The American Physical Society
One-loop Renormalization of Resonance Chiral Theory with Scalar and Pseudoscalar Resonances
International Nuclear Information System (INIS)
Rosell, I.
2007-01-01
The divergent part of the generating functional of the Resonance Chiral Theory is evaluated up to one loop when one multiplet of scalar and pseudoscalar resonances are included and interaction terms which couple up to two resonances are considered. Hence we obtain the renormalization of the couplings of the initial Lagrangian and, moreover, the complete list of operators that make this theory finite, at this order
Meson-baryon scattering in manifestly Lorentz invariant chiral perturbation theory
International Nuclear Information System (INIS)
Mai, Maxim; Bruns, Peter C.; Kubis, Bastian; Meissner, Ulf-G.
2011-01-01
We analyze meson-baryon scattering lengths in the framework of covariant baryon chiral perturbation theory at leading one-loop order. We compute the complete set of matching relations between the dimension-two low-energy constants in the two- and three-flavor formulations of the theory. We derive new two-flavor low-energy theorems for pion-hyperon scattering that can be tested in lattice simulations.
Aspects of meson-baryon scattering in three- and two-flavor chiral perturbation theory
International Nuclear Information System (INIS)
Mai, Maxim; Bruns, Peter C.; Kubis, Bastian; Meissner, Ulf-G.
2009-01-01
We analyze meson-baryon scattering lengths in the framework of covariant baryon chiral perturbation theory at leading one-loop order. We compute the complete set of matching relations between the dimension-two low-energy constants in the two- and three-flavor formulations of the theory. We derive new two-flavor low-energy theorems for pion-hyperon scattering that can be tested in lattice simulations.
International Nuclear Information System (INIS)
Kubo, H.; Harada, K.; Sakaeda, T.; Yamamoto, Y.
2013-01-01
On the basis of the Wilsonian renormalization group (WRG) analysis of nuclear effective field theory (NEFT) including pions, we propose a practical calculational scheme in which the short-distance part of one-pion exchange (S-OPE) is removed and represented as contact terms. The long-distance part of one-pion exchange (L-OPE) is treated as perturbation. The use of dimensional regularization (DR) for diagrams consisting only of contact interactions considerably simplifies the calculation of scattering amplitude and the renormalization group equations. NLO results for nucleon-nucleon elastic scattering in the S-waves are obtained and compared with experiments. A brief comment on NNLO calculations is given. (author)
Price, Layne C.
2015-11-01
We consider a phenomenological model of inflation where the inflaton is the phase of a complex scalar field Φ . Planck-suppressed operators of O (f5/Mpl) modify the geometry of the vev ⟨Φ ⟩ at first order in the decay constant f , which adds a first-order periodic term to the definition of the canonically normalized inflaton ϕ . This correction to the inflaton induces a fixed number of extra oscillatory terms in the potential V ˜θp. We derive the same result in a toy scenario where the vacuum ⟨Φ ⟩ is an ellipse with an arbitrarily large eccentricity. These extra oscillations change the form of the power spectrum as a function of scale k and provide a possible mechanism for differentiating effective field theory motivated inflation from models where the angular shift symmetry is a gauge symmetry.
Radiation reaction for spinning bodies in effective field theory. I. Spin-orbit effects
Maia, Natália T.; Galley, Chad R.; Leibovich, Adam K.; Porto, Rafael A.
2017-10-01
We compute the leading post-Newtonian (PN) contributions at linear order in the spin to the radiation-reaction acceleration and spin evolution for binary systems, which enter at fourth PN order. The calculation is carried out, from first principles, using the effective field theory framework for spinning compact objects, in both the Newton-Wigner and covariant spin supplementary conditions. A nontrivial consistency check is performed on our results by showing that the energy loss induced by the resulting radiation-reaction force is equivalent to the total emitted power in the far zone, up to so-called "Schott terms." We also find that, at this order, the radiation reaction has no net effect on the evolution of the spins. The spin-spin contributions to radiation reaction are reported in a companion paper.
Effective field theory analysis on μ problem in low-scale gauge mediation
International Nuclear Information System (INIS)
Zheng Sibo
2012-01-01
Supersymmetric models based on the scenario of gauge mediation often suffer from the well-known μ problem. In this paper, we reconsider this problem in low-scale gauge mediation in terms of effective field theory analysis. In this paradigm, all high energy input soft mass can be expressed via loop expansions. If the corrections coming from messenger thresholds are small, as we assume in this letter, then all RG evaluations can be taken as linearly approximation for low-scale supersymmetric breaking. Due to these observations, the parameter space can be systematically classified and studied after constraints coming from electro-weak symmetry breaking are imposed. We find that some old proposals in the literature are reproduced, and two new classes are uncovered. We refer to a microscopic model, where the specific relations among coefficients in one of the new classes are well motivated. Also, we discuss some primary phenomenologies.
Effective field theory of emergent symmetry breaking in deformed atomic nuclei
International Nuclear Information System (INIS)
Papenbrock, T; Weidenmüller, H A
2015-01-01
Spontaneous symmetry breaking in non-relativistic quantum systems has previously been addressed in the framework of effective field theory. Low-lying excitations are constructed from Nambu–Goldstone modes using symmetry arguments only. We extend that approach to finite systems. The approach is very general. To be specific, however, we consider atomic nuclei with intrinsically deformed ground states. The emergent symmetry breaking in such systems requires the introduction of additional degrees of freedom on top of the Nambu–Goldstone modes. Symmetry arguments suffice to construct the low-lying states of the system. In deformed nuclei these are vibrational modes each of which serves as band head of a rotational band. (paper)
On the covariant formalism of the effective field theory of gravity and leading order corrections
DEFF Research Database (Denmark)
Codello, Alessandro; Jain, Rajeev Kumar
2016-01-01
We construct the covariant effective field theory of gravity as an expansion in inverse powers of the Planck mass, identifying the leading and next-to-leading quantum corrections. We determine the form of the effective action for the cases of pure gravity with cosmological constant as well...... as gravity coupled to matter. By means of heat kernel methods we renormalize and compute the leading quantum corrections to quadratic order in a curvature expansion. The final effective action in our covariant formalism is generally non-local and can be readily used to understand the phenomenology...... on different spacetimes. In particular, we point out that on curved backgrounds the observable leading quantum gravitational effects are less suppressed than on Minkowski spacetime....
On the covariant formalism of the effective field theory of gravity and leading order corrections
International Nuclear Information System (INIS)
Codello, Alessandro; Jain, Rajeev Kumar
2016-01-01
We construct the covariant effective field theory of gravity as an expansion in inverse powers of the Planck mass, identifying the leading and next-to-leading quantum corrections. We determine the form of the effective action for the cases of pure gravity with cosmological constant as well as gravity coupled to matter. By means of heat kernel methods we renormalize and compute the leading quantum corrections to quadratic order in a curvature expansion. The final effective action in our covariant formalism is generally non-local and can be readily used to understand the phenomenology on different spacetimes. In particular, we point out that on curved backgrounds the observable leading quantum gravitational effects are less suppressed than on Minkowski spacetime. (paper)
Coordinate and Kaehler σ-model anomalies and their cancellation in string effective field theories
International Nuclear Information System (INIS)
Lopes Cardoso, G.; Ovrut, B.A.
1993-01-01
We discuss the complete set of one-loop triangle graphs involving the Yang-Mills gauge connection, the Kaehler connection and the σ-model coordinate connection in the effective field theory of (2, 2) symmetric Z N orbifolds. That is, we discuss pure gauge, pure Kaehler and pure σ-model coordinate anomalies as well as the mixed anomalies, such as Kaehler-gauge, some of which have been discussed elsewhere. We propose a mechanism for restoring both Kaehler and σ-model coordinate symmetry based upon the introduction of two types of counterterms. Finally, we enlarge σ-model generalization of the Green-Schwarz mechanism to allow the removal of the universal parts of a wider class of anomalies than those previously discussed. (orig.)
Effective field theory of integrating out sfermions in the MSSM: Complete one-loop analysis
Huo, Ran
2018-04-01
We apply the covariant derivative expansion of the Coleman-Weinberg potential to the sfermion sector in the minimal supersymmetric standard model, matching it to the relevant dimension-6 operators in the standard model effective field theory at one-loop level. Emphasis is paid to nondegenerate large soft supersymmetry breaking mass squares, and the most general analytical Wilson coefficients are obtained for all pure bosonic dimension-6 operators. In addition to the non-logarithmic contributions, they generally have another logarithmic contributions. Various numerical results are shown, in particular the constraints in the large Xt branch reproducing the 125 GeV Higgs mass can be pushed to high values to almost completely probe the low stop mass region at the future FCC-ee experiment, even given the Higgs mass calculation uncertainty.
International Nuclear Information System (INIS)
Ananthanarayan, B.; Sentitemsu Imsong, I.; Das, Diganta
2012-01-01
Ampcalculator (AMPC) is a Mathematica copyright based program that was made publicly available some time ago by Unterdorfer and Ecker. It enables the user to compute several processes at one loop (upto O(p 4 )) in SU(3) chiral perturbation theory. They include computing matrix elements and form factors for strong and non-leptonic weak processes with at most six external states. It was used to compute some novel processes and was tested against well-known results by the original authors. Here we present the results of several thorough checks of the package. Exhaustive checks performed by the original authors are not publicly available, and hence the present effort. Some new results are obtained from the software especially in the kaon odd-intrinsic parity non-leptonic decay sector involving the coupling G 27 . Another illustrative set of amplitudes at tree level we provide is in the context of τ-decays with several mesons including quark mass effects, of use to the BELLE experiment. All eight meson-meson scattering amplitudes have been checked. The Kaon-Compton amplitude has been checked and a minor error in the published results has been pointed out. This exercise is a tutorial-based one, wherein several input and output notebooks are also being made available as ancillary files on the arXiv. Some of the additional notebooks we provide contain explicit expressions that we have used for comparison with established results. The purpose is to encourage users to apply the software to suit their specific needs. An automatic amplitude generator of this type can provide error-free outputs that could be used as inputs for further simplification, and in varied scenarios such as applications of chiral perturbation theory at finite temperature, density and volume. This can also be used by students as a learning aid in low-energy hadron dynamics. (orig.)
Setting limits on Effective Field Theories: the case of Dark Matter
Pobbe, Federico; Wulzer, Andrea; Zanetti, Marco
2017-08-01
The usage of Effective Field Theories (EFT) for LHC new physics searches is receiving increasing attention. It is thus important to clarify all the aspects related with the applicability of the EFT formalism in the LHC environment, where the large available energy can produce reactions that overcome the maximal range of validity, i.e. the cutoff, of the theory. We show that this does not forbid to set rigorous limits on the EFT parameter space through a modified version of the ordinary binned likelihood hypothesis test, which we design and validate. Our limit-setting strategy can be carried on in its full-fledged form by the LHC experimental collaborations, or performed externally to the collaborations, through the Simplified Likelihood approach, by relying on certain approximations. We apply it to the recent CMS mono-jet analysis and derive limits on a Dark Matter (DM) EFT model. DM is selected as a case study because the limited reach on the DM production EFT Wilson coefficient and the structure of the theory suggests that the cutoff might be dangerously low, well within the LHC reach. However our strategy can also be applied, if needed, to EFT's parametrising the indirect effects of heavy new physics in the Electroweak and Higgs sectors.
Probing scalar effective field theories with the soft limits of scattering amplitudes
Energy Technology Data Exchange (ETDEWEB)
Padilla, Antonio [School of Physics and Astronomy, University of Nottingham,University Park, Nottingham, NG7 2RD United Kingdom (United Kingdom); Stefanyszyn, David [Van Swinderen Institute for Particle Physics and Gravity, University of Groningen,Nijenborgh 4, Groningen, 9747 AG The (Netherlands); Wilson, Toby [School of Physics and Astronomy, University of Nottingham,University Park, Nottingham, NG7 2RD United Kingdom (United Kingdom)
2017-04-04
We investigate the soft behaviour of scalar effective field theories (EFTs) when there is a number of distinct derivative power counting parameters, ρ{sub 1}<ρ{sub 2}<…<ρ{sub Q}. We clarify the notion of an enhanced soft limit and use these to extend the scope of on-shell recursion techniques for scalar EFTs. As an example, we perform a detailed study of theories with two power counting parameters, ρ{sub 1}=1 and ρ{sub 2}=2, that include the shift symmetric generalised galileons. We demonstrate that the minimally enhanced soft limit uniquely picks out the Dirac-Born-Infeld (DBI) symmetry, including DBI galileons. For the exceptional soft limit we uniquely pick out the special galileon within the class of theories under investigation. We study the DBI galileon amplitudes more closely, verifying the validity of the recursion techniques in generating the six point amplitude, and explicitly demonstrating the invariance of all amplitudes under DBI galileon duality.
Kinetic Ising model in a time-dependent oscillating external magnetic field: effective-field theory
International Nuclear Information System (INIS)
Deviren, Bayram; Canko, Osman; Keskin, Mustafa
2010-01-01
Recently, Shi et al. [2008 Phys. Lett. A 372 5922] have studied the dynamical response of the kinetic Ising model in the presence of a sinusoidal oscillating field and presented the dynamic phase diagrams by using an effective-field theory (EFT) and a mean-field theory (MFT). The MFT results are in conflict with those of the earlier work of Tomé and de Oliveira, [1990 Phys. Rev. A 41 4251]. We calculate the dynamic phase diagrams and find that our results are similar to those of the earlier work of Tomé and de Oliveira; hence the dynamic phase diagrams calculated by Shi et al. are incomplete within both theories, except the low values of frequencies for the MFT calculation. We also investigate the influence of external field frequency (ω) and static external field amplitude (h 0 ) for both MFT and EFT calculations. We find that the behaviour of the system strongly depends on the values of ω and h 0 . (general)
Feynman rules for the Standard Model Effective Field Theory in R ξ -gauges
Dedes, A.; Materkowska, W.; Paraskevas, M.; Rosiek, J.; Suxho, K.
2017-06-01
We assume that New Physics effects are parametrized within the Standard Model Effective Field Theory (SMEFT) written in a complete basis of gauge invariant operators up to dimension 6, commonly referred to as "Warsaw basis". We discuss all steps necessary to obtain a consistent transition to the spontaneously broken theory and several other important aspects, including the BRST-invariance of the SMEFT action for linear R ξ -gauges. The final theory is expressed in a basis characterized by SM-like propagators for all physical and unphysical fields. The effect of the non-renormalizable operators appears explicitly in triple or higher multiplicity vertices. In this mass basis we derive the complete set of Feynman rules, without resorting to any simplifying assumptions such as baryon-, lepton-number or CP conservation. As it turns out, for most SMEFT vertices the expressions are reasonably short, with a noticeable exception of those involving 4, 5 and 6 gluons. We have also supplemented our set of Feynman rules, given in an appendix here, with a publicly available Mathematica code working with the FeynRules package and producing output which can be integrated with other symbolic algebra or numerical codes for automatic SMEFT amplitude calculations.
Beyond effective field theory for dark matter searches at the LHC
International Nuclear Information System (INIS)
Buchmueller, O.; Dolan, Matthew J.; McCabe, Christopher
2014-01-01
We study the validity of effective field theory (EFT) interpretations of monojet searches for dark matter at the LHC for vector and axial-vector interactions. We show that the EFT approach is valid when the mediator has mass m med greater than 2.5 TeV. We find that the current limits on the contact interaction scale Λ in the EFT apply to theories that are perturbative for dark matter mass m DM <800 GeV. However, for all values of m DM in these theories, the mediator width is larger than the mass, so that a particle-like interpretation of the mediator is doubtful. Furthermore, consistency with the thermal relic density occurs only for 170≲m DM ≲510 GeV. For lighter mediator masses, the EFT limit either under-estimates the true limit (because the process is resonantly enhanced) or over-estimates it (because the missing energy distribution is too soft). We give some ‘rules of thumb’ that can be used to estimate the limit on Λ (to an accuracy of ∼50%) for any m DM and m med from knowledge of the EFT limit. We also compare the relative sensitivities of monojet and dark matter direct detection searches finding that both dominate in different regions of the m DM – m med plane. Comparing only the EFT limit with direct searches is misleading and can lead to incorrect conclusions about the relative sensitivity of the two search approaches
On the renormalization of the effective field theory of large scale structures
International Nuclear Information System (INIS)
Pajer, Enrico; Zaldarriaga, Matias
2013-01-01
Standard perturbation theory (SPT) for large-scale matter inhomogeneities is unsatisfactory for at least three reasons: there is no clear expansion parameter since the density contrast is not small on all scales; it does not fully account for deviations at large scales from a perfect pressureless fluid induced by short-scale non-linearities; for generic initial conditions, loop corrections are UV-divergent, making predictions cutoff dependent and hence unphysical. The Effective Field Theory of Large Scale Structures successfully addresses all three issues. Here we focus on the third one and show explicitly that the terms induced by integrating out short scales, neglected in SPT, have exactly the right scale dependence to cancel all UV-divergences at one loop, and this should hold at all loops. A particularly clear example is an Einstein deSitter universe with no-scale initial conditions P in ∼ k n . After renormalizing the theory, we use self-similarity to derive a very simple result for the final power spectrum for any n, excluding two-loop corrections and higher. We show how the relative importance of different corrections depends on n. For n ∼ −1.5, relevant for our universe, pressure and dissipative corrections are more important than the two-loop corrections
On the renormalization of the effective field theory of large scale structures
Energy Technology Data Exchange (ETDEWEB)
Pajer, Enrico [Department of Physics, Princeton University, Princeton, NJ 08544 (United States); Zaldarriaga, Matias, E-mail: enrico.pajer@gmail.com, E-mail: matiasz@ias.edu [Institute for Advanced Study, Princeton, NJ 08544 (United States)
2013-08-01
Standard perturbation theory (SPT) for large-scale matter inhomogeneities is unsatisfactory for at least three reasons: there is no clear expansion parameter since the density contrast is not small on all scales; it does not fully account for deviations at large scales from a perfect pressureless fluid induced by short-scale non-linearities; for generic initial conditions, loop corrections are UV-divergent, making predictions cutoff dependent and hence unphysical. The Effective Field Theory of Large Scale Structures successfully addresses all three issues. Here we focus on the third one and show explicitly that the terms induced by integrating out short scales, neglected in SPT, have exactly the right scale dependence to cancel all UV-divergences at one loop, and this should hold at all loops. A particularly clear example is an Einstein deSitter universe with no-scale initial conditions P{sub in} ∼ k{sup n}. After renormalizing the theory, we use self-similarity to derive a very simple result for the final power spectrum for any n, excluding two-loop corrections and higher. We show how the relative importance of different corrections depends on n. For n ∼ −1.5, relevant for our universe, pressure and dissipative corrections are more important than the two-loop corrections.
Spinning gravitating objects in the effective field theory in the post-Newtonian scheme
Energy Technology Data Exchange (ETDEWEB)
Levi, Michele [Université Pierre et Marie Curie-Paris VI, CNRS-UMR 7095,Institut d’Astrophysique de Paris, 98 bis Boulevard Arago, 75014 Paris (France); Sorbonne Universités, Institut Lagrange de Paris,98 bis Boulevard Arago, 75014 Paris (France); Steinhoff, Jan [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute),Am Mühlenberg 1, 14476 Potsdam-Golm (Germany); Centro Multidisciplinar de Astrofisica, Instituto Superior Tecnico, Universidade de Lisboa,Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal)
2015-09-30
We introduce a formulation for spinning gravitating objects in the effective field theory in the post-Newtonian scheme in the context of the binary inspiral problem. We aim at an effective action, where all field modes below the orbital scale are integrated out. We spell out the relevant degrees of freedom, in particular the rotational ones, and the associated symmetries. Building on these symmetries, we introduce the minimal coupling part of the point particle action in terms of gauge rotational variables, and construct the spin-induced nonminimal couplings, where we obtain the leading order couplings to all orders in spin. We specify the gauge for the rotational variables, where the unphysical degrees of freedom are eliminated already from the Feynman rules, and all the orbital field modes are integrated out. The equations of motion of the spin can be directly obtained via a proper variation of the action, and Hamiltonians may be straightforwardly derived. We implement this effective field theory for spin to derive all spin dependent potentials up to next-to-leading order to quadratic level in spin, namely up to the third post-Newtonian order for rapidly rotating compact objects. In particular, the proper next-to-leading order spin-squared potential and Hamiltonian for generic compact objects are also derived. For the implementations we use the nonrelativistic gravitational field decomposition, which is found here to eliminate higher-loop Feynman diagrams also in spin dependent sectors, and facilitates derivations. This formulation for spin is thus ideal for treatment of higher order spin dependent sectors.
Point-particle effective field theory I: classical renormalization and the inverse-square potential
Energy Technology Data Exchange (ETDEWEB)
Burgess, C.P.; Hayman, Peter [Physics & Astronomy, McMaster University,Hamilton, ON, L8S 4M1 (Canada); Perimeter Institute for Theoretical Physics,Waterloo, Ontario N2L 2Y5 (Canada); Williams, M. [Instituut voor Theoretische Fysica, KU Leuven,Celestijnenlaan 200D, B-3001 Leuven (Belgium); Zalavári, László [Physics & Astronomy, McMaster University,Hamilton, ON, L8S 4M1 (Canada); Perimeter Institute for Theoretical Physics,Waterloo, Ontario N2L 2Y5 (Canada)
2017-04-19
Singular potentials (the inverse-square potential, for example) arise in many situations and their quantum treatment leads to well-known ambiguities in choosing boundary conditions for the wave-function at the position of the potential’s singularity. These ambiguities are usually resolved by developing a self-adjoint extension of the original problem; a non-unique procedure that leaves undetermined which extension should apply in specific physical systems. We take the guesswork out of this picture by using techniques of effective field theory to derive the required boundary conditions at the origin in terms of the effective point-particle action describing the physics of the source. In this picture ambiguities in boundary conditions boil down to the allowed choices for the source action, but casting them in terms of an action provides a physical criterion for their determination. The resulting extension is self-adjoint if the source action is real (and involves no new degrees of freedom), and not otherwise (as can also happen for reasonable systems). We show how this effective-field picture provides a simple framework for understanding well-known renormalization effects that arise in these systems, including how renormalization-group techniques can resum non-perturbative interactions that often arise, particularly for non-relativistic applications. In particular we argue why the low-energy effective theory tends to produce a universal RG flow of this type and describe how this can lead to the phenomenon of reaction catalysis, in which physical quantities (like scattering cross sections) can sometimes be surprisingly large compared to the underlying scales of the source in question. We comment in passing on the possible relevance of these observations to the phenomenon of the catalysis of baryon-number violation by scattering from magnetic monopoles.
An Ultraviolet Chiral Theory of the Top for the Fundamental Composite (Goldstone) Higgs
DEFF Research Database (Denmark)
Cacciapaglia, Giacomo; Sannino, Francesco
2016-01-01
We introduce a scalar-less anomaly free chiral gauge theory that serves as natural ultraviolet completion of models of fundamental composite (Goldstone) Higgs dynamics. The new theory is able to generate the top mass and furthermore features a built-in protection mechanism that naturally suppresses...... the bottom mass. At low energies the theory predicts new fractionally charged fermions, and a number of four-fermion operators that, besides being relevant for the generation of the top mass, also lead to an intriguing phenomenology for the new states predicted by the theory....
An ultraviolet chiral theory of the top for the fundamental composite (Goldstone) Higgs
Energy Technology Data Exchange (ETDEWEB)
Cacciapaglia, Giacomo, E-mail: g.cacciapaglia@ipnl.in2p3.fr [Univ Lyon, Université Lyon 1, CNRS/IN2P3, IPNL, 4 rue Enrico Fermi, F-69622 Villeurbanne Cedex (France); Sannino, Francesco, E-mail: sannino@cp3.dias.sdu.dk [CP" 3-Origins and the Danish IAS, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark)
2016-04-10
We introduce a scalar-less anomaly free chiral gauge theory that serves as natural ultraviolet completion of models of fundamental composite (Goldstone) Higgs dynamics. The new theory is able to generate the top mass and furthermore features a built-in protection mechanism that naturally suppresses the bottom mass. At low energies the theory predicts new fractionally charged fermions, and a number of four-fermion operators that, besides being relevant for the generation of the top mass, also lead to an intriguing phenomenology for the new states predicted by the theory.
Effective field theory of an anomalous Hall metal from interband quantum fluctuations
Chua, Victor; Assawasunthonnet, Wathid; Fradkin, Eduardo
2017-07-01
We construct an effective field theory, a two-dimensional two-component metallic system described by a model with two Fermi surfaces ("pockets"). This model describes a translationally invariant metallic system with two types of fermions, each with its own Fermi surface, with forward scattering interactions. This model, in addition to the O (2 ) rotational invariance, has a U (1 )×U (1 ) symmetry of separate charge conservation for each Fermi surface. For sufficiently attractive interactions in the d -wave (quadrupolar) channel, this model has an interesting phase diagram that includes a spontaneously generated anomalous Hall metal phase. We derive the Landau-Ginzburg effective action of quadrupolar order parameter fields which enjoys an O (2 )×U (1 ) global symmetry associated to spatial isotropy and the internal U (1 ) relative phase symmetries, respectively. We show that the order parameter theory is dynamically local with a dynamical scaling of z =2 and perform a one-loop renormalization group analysis of the Landau-Ginzburg theory. The electronic liquid crystal phases that result from spontaneous symmetry breaking are studied and we show the presence of Landau damped Nambu-Goldstone modes at low momenta that is a signature of non-Fermi-liquid behavior. Electromagnetic linear response is also analyzed in both the normal and symmetry broken phases from the point of view of the order parameter theory. The nature of the coupling of electromagnetism to the order parameter fields in the normal phase is non-minimal and decidedly contains a precursor to the anomalous Hall response in the form of a order-parameter-dependent Chern-Simons term in the effective action.
String-theoretic breakdown of effective field theory near black hole horizons
Dodelson, Matthew; Silverstein, Eva
2017-09-01
We investigate the validity of the equivalence principle near horizons in string theory, analyzing the breakdown of effective field theory caused by longitudinal string spreading effects. An experiment is set up where a detector is thrown into a black hole a long time after an early infalling string. Light cone gauge calculations, taken at face value, indicate a detectable level of root-mean-square longitudinal spreading of the initial string as measured by the late infaller. This results from the large relative boost between the string and detector in the near-horizon region, which develops automatically despite their modest initial energies outside the black hole and the weak curvature in the geometry. We subject this scenario to basic consistency checks, using these to obtain a relatively conservative criterion for its detectability. In a companion paper, we exhibit longitudinal nonlocality in well-defined gauge-invariant S-matrix calculations, obtaining results consistent with the predicted spreading albeit not in a direct analog of the black hole process. We discuss applications of this effect to the firewall paradox, and estimate the time and distance scales it predicts for new physics near black hole and cosmological horizons.
Properties of Lithium-11 and Carbon-22 at leading order in halo effective field theory
Directory of Open Access Journals (Sweden)
Acharya Bijaya
2016-01-01
Full Text Available We study the 11Li and 22C nuclei at leading order (LO in halo effective field theory (Halo EFT. Using the value of the 22C rms matter radius deduced in Ref. [1] as an input in a LO calculation, we simultaneously constrain the values of the two-neutron (2n separation energy of 22C and the virtual-state energy of the 20C−neutron system (hereafter denoted 21C. The 1−σ uncertainty of the input rms matter radius datum, along with the theory error estimated from the anticipated size of the higher-order terms in the Halo EFT expansion, gives an upper bound of about 100 keV for the 2n separation energy. We also study the electric dipole excitation of 2n halo nuclei to a continuum state of two neutrons and the core at LO in Halo EFT. We first compare our results with the 11Li data from a Coulomb dissociation experiment and obtain good agreement within the theoretical uncertainty of a LO calculation. We then obtain the low-energy spectrum of B(E1 of this transition at several different values of the 2n separation energy of 22C and the virtual-state energy of 21C. Our predictions can be compared to the outcome of an ongoing experiment on the Coulomb dissociation of 22C to obtain tighter constraints on the two- and three-body energies in the 22C system.
A multipole-expanded effective field theory for vortex ring-sound interactions
Garcia-Saenz, Sebastian; Mitsou, Ermis; Nicolis, Alberto
2018-02-01
The low-energy dynamics of a zero temperature superfluid or of the compressional modes of an ordinary fluid can be described by a simple effective theory for a scalar field — the superfluid `phase'. However, when vortex lines are present, to describe all interactions in a local fashion one has to switch to a magnetic-type dual two-form description, which comes with six degrees of freedom (in place of one) and an associated gauge redundancy, and is thus considerably more complicated. Here we show that, in the case of vortex rings and for bulk modes that are much longer than the typical ring size, one can perform a systematic multipole expansion of the effective action and recast it into the simpler scalar field language. In a sense, in the presence of vortex rings the non-single valuedness of the scalar can be hidden inside the rings, and thus out of the reach of the multipole expansion. As an application of our techniques, we compute by standard effective field theory methods the sound emitted by an oscillating vortex ring.
Effective field theory approach to open heavy flavor production in heavy-ion collisions
Energy Technology Data Exchange (ETDEWEB)
Kang, Zhong-Bo [Department of Physics and Astronomy, University of California,Los Angeles, California 90095 (United States); Mani L. Bhaumik Institute for Theoretical Physics, University of California,Los Angeles, California 90095 (United States); Theoretical Division, Los Alamos National Laboratory,Los Alamos, New Mexico 87545 (United States); Ringer, Felix; Vitev, Ivan [Theoretical Division, Los Alamos National Laboratory,Los Alamos, New Mexico 87545 (United States)
2017-03-28
We develop a version of Soft Collinear Effective Theory (SCET) which includes finite quark masses, as well as Glauber gluons that describe the interaction of collinear partons with QCD matter. In the framework of this new effective field theory, labeled SCET{sub M,G}, we derive the massive splitting functions in the vacuum and the QCD medium for the processes Q→Qg, Q→gQ and g→QQ̄. The numerical effects due to finite quark masses are sizable and our results are consistent with the traditional approach to parton energy loss in the soft gluon emission limit. In addition, we present a new framework for including the medium-induced full splitting functions consistent with next-to-leading order calculations in QCD for inclusive hadron production. Finally, we show numerical results for the suppression of D- and B-mesons in heavy ion collisions at √(s{sub NN})=5.02 TeV and 2.76 TeV and compare to available data from the LHC.
Energy Technology Data Exchange (ETDEWEB)
Bauer, Torsten
2012-07-11
In the first part of the this doctoral thesis the perturbative unitarity in the complex-mass scheme (CMS) is analysed. To that end a procedure for calculating cutting rules for loop integrals containing propagators with finite widths is presented. A toy-model Lagrangian describing the interaction of a heavy vector boson with a light fermion is used to demonstrate that the CMS respects unitarity order by order in perturbation theory provided that the renormalized coupling constant remains real. The second part of the thesis deals with various applications of the CMS to chiral effective field theory (EFT). In particular, mass and width of the delta resonance, elastic electromagnetic form factors of the Roper resonance, form factors of the nucleon-to-Roper transition, pion-nucleon scattering, and pion photo- and electroproduction for center-of-mass energies in the region of the Roper mass are calculated. By choosing appropriate renormalization conditions, a consistent chiral power counting scheme for EFT with resonant degrees of freedom can be established. This allows for a systematic investigation of the above processes in terms of an expansion in small quantities. The obtained results can be applied to the extrapolation of corresponding simulations in the context of lattice QCD to the physical value of the pion mass. Therefore, in addition to the Q{sup 2} dependence of the form factors, also the pion-mass dependence of the magnetic moment and electromagnetic radii of the Roper resonance is explored. Both a partial wave decomposition and a multipole expansion are performed for pion-nucleon scattering and pion photo- and electroproduction, respectively. In this connection the P11 partial wave as well as the M{sub 1-} and S{sub 1-} multipoles are fitted via non-linear regression to empirical data.
Baryon chiral perturbation theory extended beyond the low-energy region.
Epelbaum, E; Gegelia, J; Meißner, Ulf-G; Yao, De-Liang
We consider an extension of the one-nucleon sector of baryon chiral perturbation theory beyond the low-energy region. The applicability of this approach for higher energies is restricted to small scattering angles, i.e. the kinematical region, where the quark structure of hadrons cannot be resolved. The main idea is to re-arrange the low-energy effective Lagrangian according to a new power counting and to exploit the freedom of the choice of the renormalization condition for loop diagrams. We generalize the extended on-mass-shell scheme for the one-nucleon sector of baryon chiral perturbation theory by choosing a sliding scale, that is, we expand the physical amplitudes around kinematical points beyond the threshold. This requires the introduction of complex-valued renormalized coupling constants, which can be either extracted from experimental data, or calculated using the renormalization group evolution of coupling constants fixed in threshold region.
Baryon chiral perturbation theory extended beyond the low-energy region
International Nuclear Information System (INIS)
Epelbaum, E.; Gegelia, J.; Meissner, Ulf G.; Yao, De-Liang
2015-01-01
We consider an extension of the one-nucleon sector of baryon chiral perturbation theory beyond the low-energy region. The applicability of this approach for higher energies is restricted to small scattering angles, i.e. the kinematical region, where the quark structure of hadrons cannot be resolved. The main idea is to re-arrange the low-energy effective Lagrangian according to a new power counting and to exploit the freedom of the choice of the renormalization condition for loop diagrams. We generalize the extended on-mass-shell scheme for the one-nucleon sector of baryon chiral perturbation theory by choosing a sliding scale, that is, we expand the physical amplitudes around kinematical points beyond the threshold. This requires the introduction of complex-valued renormalized coupling constants, which can be either extracted from experimental data, or calculated using the renormalization group evolution of coupling constants fixed in threshold region. (orig.)
International Nuclear Information System (INIS)
Townsend, P.K.; Sierra, G.
1983-01-01
Chiral anomalies for gauge theories in any even dimension are computed and the results applied to supersymmetric theories in D=6, 8 and 10. For D=8 there is an anomalous chiral U(1) invariance, just as in D=4, except for certain special groups. For D=6 and D=10 there is no anomalous chiral U(1) symmetry, but the gauge current is anomalous except for certain ''anomaly-free'' groups. For D=6 the group is thereby constrained to be one of [SU(2), SU(3), exceptional], while for D=10 it is constrained to be one of [SU(n)n 8 ]. (orig.)
Higgs-Yukawa model in chirally-invariant lattice field theory
Bulava, John; Jansen, Karl; Kallarackal, Jim; Knippschild, Bastian; Lin, C.-J.David; Nagai, Kei-Ichi; Nagy, Attila; Ogawa, Kenji
2013-01-01
Non-perturbative numerical lattice studies of the Higgs-Yukawa sector of the standard model with exact chiral symmetry are reviewed. In particular, we discuss bounds on the Higgs boson mass at the standard model top quark mass, and in the presence of heavy fermions. We present a comprehensive study of the phase structure of the theory at weak and very strong values of the Yukawa coupling as well as at non-zero temperature.
Determination of low-energy constants of Wilson chiral perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Herdoiza, Gregorio [Mainz Univ. (Germany). Inst fuer Kernphysik, PRISMA Cluster of Excellence; Univ. Autonoma de Madrid, Contoblanco (Spain). Dept. de Fisica Teorica; Univ. Autonoma de Madrid (Spain). Inst. de Fisica Teorica UAM/CSIC; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Univ. Cyprus, Nicosia (Cyprus). Dept. of Physics; Michael, Chris [Liverpool Univ. (United Kingdom). Theoretical Physics Division; Ottnad, Konstantin; Urbach, Carsten [Bonn Univ. (Germany). Helmholtz-Institut fuer Strahlen und Kernphysik; Univ. Bonn (Germany). Bethe Center for Theoretical Physics; Collaboration: European Twisted Mass Collaboration
2013-03-15
By matching Wilson twisted mass lattice QCD determinations of pseudoscalar meson masses to Wilson Chiral Perturbation Theory we determine the low-energy constants W{sub 6}{sup '}, W{sub 8}{sup '} and their linear combination c{sub 2}. We explore the dependence of these low-energy constants on the choice of the lattice action and on the number of dynamical flavours.
Higgs-Yukawa model in chirally-invariant lattice field theory
Energy Technology Data Exchange (ETDEWEB)
Bulava, John [CERN, Geneva (Switzerland). Physics Department; Gerhold, Philipp; Kallarackal, Jim; Nagy, Attila [Humboldt Univ. Berlin (Germany). Inst. fuer Physik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Knippschild, Bastian [National Taiwan Univ., Taipei (China). Dept. of Physics; Lin, C.J. David [National Chiao-Tung Univ., Hsinchu (China). Inst. of Physics; National Centre for Theoretical Sciences, Hsinchu (China). Div. of Physics; Nagai, Kei-Ichi [Nagoya Univ., Nagoya, Aichi (Japan). Kobayashi-Maskawa Institute; Ogawa, Kenji [Chung-Yuan Christian Univ., Chung-Li (China). Dept. of Physics
2012-10-15
Non-perturbative numerical lattice studies of the Higgs-Yukawa sector of the standard model with exact chiral symmetry are reviewed. In particular, we discuss bounds on the Higgs boson mass at the standard model top quark mass, and in the presence of heavy fermions. We present a comprehensive study of the phase structure of the theory at weak and very strong values of the Yukawa coupling as well as at non-zero temperature.
Quark model with chiral-symmetry breaking and confinement in the Covariant Spectator Theory
Energy Technology Data Exchange (ETDEWEB)
Biernat, Elmer P. [CFTP, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Pena, Maria Teresa [CFTP, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Departamento de FÃsica, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Ribiero, Jose' Emilio F. [CeFEMA, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Stadler, Alfred [Departamento de FÃsica, Universidade de Ãvora, 7000-671 Ãvora, Portugal; Gross, Franz L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-03-01
We propose a model for the quark-antiquark interaction in Minkowski space using the Covariant Spectator Theory. We show that with an equal-weighted scalar-pseudoscalar structure for the confining part of our interaction kernel the axial-vector Ward-Takahashi identity is preserved and our model complies with the Adler-zero constraint for pi-pi-scattering imposed by chiral symmetry.
Point-splitting analysis of commutator anomalies in non-abelian chiral gauge theories
International Nuclear Information System (INIS)
Ghosh, S.; Banerjee, R.
1988-01-01
A gauge covariant point-splitting regularisation is employed to calculate different anomalous commutators in four dimensional chiral gauge theories. For an external gauge field the fixed time anomalous commutator of the gauge group generators is seen to violate the Jacobi identity. The cohomological prediction can be confirmed provided the electric fields do not commute. Other commutators like the current-current and current-electric field are consistent with the Bjorken-Johnson-Low (BJL) derivation. (orig.)
Statistical approach to Higgs boson couplings in the standard model effective field theory
Murphy, Christopher W.
2018-01-01
We perform a parameter fit in the standard model effective field theory (SMEFT) with an emphasis on using regularized linear regression to tackle the issue of the large number of parameters in the SMEFT. In regularized linear regression, a positive definite function of the parameters of interest is added to the usual cost function. A cross-validation is performed to try to determine the optimal value of the regularization parameter to use, but it selects the standard model (SM) as the best model to explain the measurements. Nevertheless as proof of principle of this technique we apply it to fitting Higgs boson signal strengths in SMEFT, including the latest Run-2 results. Results are presented in terms of the eigensystem of the covariance matrix of the least squares estimators as it has a degree model-independent to it. We find several results in this initial work: the SMEFT predicts the total width of the Higgs boson to be consistent with the SM prediction; the ATLAS and CMS experiments at the LHC are currently sensitive to non-resonant double Higgs boson production. Constraints are derived on the viable parameter space for electroweak baryogenesis in the SMEFT, reinforcing the notion that a first order phase transition requires fairly low-scale beyond the SM physics. Finally, we study which future experimental measurements would give the most improvement on the global constraints on the Higgs sector of the SMEFT.
Anomalous triple gauge couplings in the effective field theory approach at the LHC
Energy Technology Data Exchange (ETDEWEB)
Falkowski, Adam [Laboratoire de Physique Théorique,Bat. 210, Université Paris-Sud, 91405 Orsay (France); González-Alonso, Martín [IPN de Lyon/CNRS,Universite Lyon 1, Villeurbanne (France); Greljo, Admir [Physik-Institut, Universität Zürich,CH-8057 Zürich (Switzerland); Faculty of Science, University of Sarajevo,Zmaja od Bosne 33-35, 71000 Sarajevo (Bosnia and Herzegovina); Marzocca, David [Physik-Institut, Universität Zürich,CH-8057 Zürich (Switzerland); Son, Minho [Department of Physics, Korea Advanced Institute of Science and Technology,291 Daehak-ro, Yuseong-gu, Daejeon 34141 (Korea, Republic of)
2017-02-22
We discuss how to perform consistent extractions of anomalous triple gauge couplings (aTGC) from electroweak boson pair production at the LHC in the Standard Model Effective Field Theory (SMEFT). After recasting recent ATLAS and CMS searches in pp→WZ(WW)→ℓ{sup ′}νℓ{sup +}ℓ{sup −}(ν{sub ℓ}) channels, we find that: (a) working consistently at order Λ{sup −2} in the SMEFT expansion the existing aTGC bounds from Higgs and LEP-2 data are not improved, (b) the strong limits quoted by the experimental collaborations are due to the partial Λ{sup −4} corrections (dimension-6 squared contributions). Using helicity selection rule arguments we are able to explain the suppression in some of the interference terms, and discuss conditions on New Physics (NP) models that can benefit from such LHC analyses. Furthermore, standard analyses assume implicitly a quite large NP scale, an assumption that can be relaxed by imposing cuts on the underlying scale of the process (√(ŝ)). In practice, we find almost no correlation between √(ŝ) and the experimentally accessible quantities, which complicates the SMEFT interpretation. Nevertheless, we provide a method to set (conservative) aTGC bounds in this situation, and recast the present searches accordingly. Finally, we introduce a simple NP model for aTGC to compare the bounds obtained directly in the model with those from the SMEFT analysis.
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.)
Regularization and the potential of effective field theory in nucleon-nucleon scattering
International Nuclear Information System (INIS)
Phillips, D.R.
1998-04-01
This paper examines the role that regularization plays in the definition of the potential used in effective field theory (EFT) treatments of the nucleon-nucleon interaction. The author considers N N scattering in S-wave channels at momenta well below the pion mass. In these channels (quasi-)bound states are present at energies well below the scale m π 2 /M expected from naturalness arguments. He asks whether, in the presence of such a shallow bound state, there is a regularization scheme which leads to an EFT potential that is both useful and systematic. In general, if a low-lying bound state is present then cutoff regularization leads to an EFT potential which is useful but not systematic, and dimensional regularization with minimal subtraction leads to one which is systematic but not useful. The recently-proposed technique of dimensional regularization with power-law divergence subtraction allows the definition of an EFT potential which is both useful and systematic
Effective field theory analysis of double Higgs production via gluon fusion
Azatov, Aleksandr; Panico, Giuliano; Son, Minho
2015-01-01
We perform a detailed study of double Higgs production via gluon fusion in the Effective Field Theory (EFT) framework where effects from new physics are parametrized by local operators. Our analysis provides a perspective broader than the one followed in most of the previous analyses, where this process was merely considered as a way to extract the Higgs trilinear coupling. We focus on the $hh \\to b\\bar b\\gamma\\gamma$ channel and perform a thorough simulation of signal and background at the 14 TeV LHC and a future 100 TeV proton-proton collider. We make use of invariant mass distributions to enhance the sensitivity on the EFT coefficients and give a first assessment of the impact of jet substructure techniques on the results. The range of validity of the EFT description is estimated, as required to consistently exploit the high-energy range of distributions, pointing out the potential relevance of dimension-8 operators. Our analysis contains a few important improvements over previous studies and identifies so...
Low-derivative operators of the Standard Model effective field theory via Hilbert series methods
Energy Technology Data Exchange (ETDEWEB)
Lehman, Landon; Martin, Adam [Department of Physics, University of Notre Dame,Nieuwland Science Hall, Notre Dame, IN 46556 (United States)
2016-02-12
In this work, we explore an extension of Hilbert series techniques to count operators that include derivatives. For sufficiently low-derivative operators, we conjecture an algorithm that gives the number of invariant operators, properly accounting for redundancies due to the equations of motion and integration by parts. Specifically, the conjectured technique can be applied whenever there is only one Lorentz invariant for a given partitioning of derivatives among the fields. At higher numbers of derivatives, equation of motion redundancies can be removed, but the increased number of Lorentz contractions spoils the subtraction of integration by parts redundancies. While restricted, this technique is sufficient to automatically recreate the complete set of invariant operators of the Standard Model effective field theory for dimensions 6 and 7 (for arbitrary numbers of flavors). At dimension 8, the algorithm does not automatically generate the complete operator set; however, it suffices for all but five classes of operators. For these remaining classes, there is a well defined procedure to manually determine the number of invariants. Assuming our method is correct, we derive a set of 535 dimension-8 N{sub f}=1 operators.
Effective Field Theories for heavy probes in a hot QCD plasma and in the early universe
Directory of Open Access Journals (Sweden)
Escobedo Miguel A.
2017-01-01
Full Text Available There are many interesting problems in heavy-ion collisions and in cosmology that involve the interaction of a heavy particle with a medium. An example is the dissociation of heavy quarkonium seen in heavy-ion collisions. This was believed to be due to the screening of chromoelectric fields that prevents the heavy quarks from binding, however in the last years several perturbative and lattice computations have pointed out to the possibility that dissociation is due to the finite lifetime of a quarkonium state inside the medium. Regarding cosmology, the study of the behavior of heavy Majorana neutrinos in a hot medium is important to understand if this model can explain the origin of dark matter and the baryon asymmetry. A very convenient way of studying these problems is with the use of non-relativistic effective field theories (EFTs, this allows to make the computations in a more systematic way by defining a more suitable power counting and making it more difficult to miss necessary resummations. In this proceedings I will review the most important results obtained by applying the EFT formalism to the study of quarkonium suppression and Majorana neutrinos, I will also discuss how combining an EFT called potential non-relativistic QCD (pNRQCD with concepts coming from the field of open quantum systems it is possible to understand how the population of the different quarkonium states evolve with time inside a thermal medium.
Liao, Yi; Ma, Xiao-Dong
2018-03-01
We study two aspects of higher dimensional operators in standard model effective field theory. We first introduce a perturbative power counting rule for the entries in the anomalous dimension matrix of operators with equal mass dimension. The power counting is determined by the number of loops and the difference of the indices of the two operators involved, which in turn is defined by assuming that all terms in the standard model Lagrangian have an equal perturbative power. Then we show that the operators with the lowest index are unique at each mass dimension d, i.e., (H † H) d/2 for even d ≥ 4, and (LT∈ H)C(LT∈ H) T (H † H)(d-5)/2 for odd d ≥ 5. Here H, L are the Higgs and lepton doublet, and ∈, C the antisymmetric matrix of rank two and the charge conjugation matrix, respectively. The renormalization group running of these operators can be studied separately from other operators of equal mass dimension at the leading order in power counting. We compute their anomalous dimensions at one loop for general d and find that they are enhanced quadratically in d due to combinatorics. We also make connections with classification of operators in terms of their holomorphic and anti-holomorphic weights. Supported by the National Natural Science Foundation of China under Grant Nos. 11025525, 11575089, and by the CAS Center for Excellence in Particle Physics (CCEPP)
Low-derivative operators of the Standard Model effective field theory via Hilbert series methods
International Nuclear Information System (INIS)
Lehman, Landon; Martin, Adam
2016-01-01
In this work, we explore an extension of Hilbert series techniques to count operators that include derivatives. For sufficiently low-derivative operators, we conjecture an algorithm that gives the number of invariant operators, properly accounting for redundancies due to the equations of motion and integration by parts. Specifically, the conjectured technique can be applied whenever there is only one Lorentz invariant for a given partitioning of derivatives among the fields. At higher numbers of derivatives, equation of motion redundancies can be removed, but the increased number of Lorentz contractions spoils the subtraction of integration by parts redundancies. While restricted, this technique is sufficient to automatically recreate the complete set of invariant operators of the Standard Model effective field theory for dimensions 6 and 7 (for arbitrary numbers of flavors). At dimension 8, the algorithm does not automatically generate the complete operator set; however, it suffices for all but five classes of operators. For these remaining classes, there is a well defined procedure to manually determine the number of invariants. Assuming our method is correct, we derive a set of 535 dimension-8 N_f=1 operators.
Principal shapes and squeezed limits in the effective field theory of large scale structure
Energy Technology Data Exchange (ETDEWEB)
Bertolini, Daniele; Solon, Mikhail P., E-mail: dbertolini@lbl.gov, E-mail: mpsolon@lbl.gov [Berkeley Center for Theoretical Physics, University of California, South Hall Road, Berkeley, CA, 94720 (United States)
2016-11-01
We apply an orthogonalization procedure on the effective field theory of large scale structure (EFT of LSS) shapes, relevant for the angle-averaged bispectrum and non-Gaussian covariance of the matter power spectrum at one loop. Assuming natural-sized EFT parameters, this identifies a linear combination of EFT shapes—referred to as the principal shape—that gives the dominant contribution for the whole kinematic plane, with subdominant combinations suppressed by a few orders of magnitude. For the covariance, our orthogonal transformation is in excellent agreement with a principal component analysis applied to available data. Additionally we find that, for both observables, the coefficients of the principal shapes are well approximated by the EFT coefficients appearing in the squeezed limit, and are thus measurable from power spectrum response functions. Employing data from N-body simulations for the growth-only response, we measure the single EFT coefficient describing the angle-averaged bispectrum with Ο (10%) precision. These methods of shape orthogonalization and measurement of coefficients from response functions are valuable tools for developing the EFT of LSS framework, and can be applied to more general observables.
International Nuclear Information System (INIS)
Cannoni, Mirco
2016-01-01
We find an exact formula for the thermally averaged cross section times the relative velocity left angle σv 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 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 rel right angle nr coinciding with the large x expansion of left angle σv 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 rel , showing the uselessness of the Moeller velocity and further elucidating the conceptual and numerical inconsistencies related with its use. (orig.)
On the validity of the effective field theory approach to SM precision tests
Energy Technology Data Exchange (ETDEWEB)
Contino, Roberto [EPFL, Lausanne (Switzerland). Inst. de Theorie des Phenomenes Physiques; CERN, Geneva (Switzerland). Theoretical Physics Dept.; Falkowski, Adam [Paris-11 Univ., 91 - Orsay (France). Lab. de Physique Theorique; Goertz, Florian; Riva, Francesco [CERN, Geneva (Switzerland). Theoretical Physics Dept.; Grojean, Christophe [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2016-09-15
We discuss the conditions for an effective field theory (EFT) to give an adequate low-energy description of an underlying physics beyond the Standard Model (SM). Starting from the EFT where the SM is extended by dimension-6 operators, experimental data can be used without further assumptions to measure (or set limits on) the EFT parameters. The interpretation of these results requires instead a set of broad assumptions (e.g. power counting rules) on the UV dynamics. This allows one to establish, in a bottom-up approach, the validity range of the EFT description, and to assess the error associated with the truncation of the EFT series. We give a practical prescription on how experimental results could be reported, so that they admit a maximally broad range of theoretical interpretations. Namely, the experimental constraints on dimension-6 operators should be reported as functions of the kinematic variables that set the relevant energy scale of the studied process. This is especially important for hadron collider experiments where collisions probe a wide range of energy scales.
Power counting regime of chiral extrapolation and beyond
International Nuclear Information System (INIS)
Derek Leinweber; Anthony Thomas; Ross Young
2005-01-01
Finite-range regularized chiral effective field theory is presented in the context of approximation schemes ubiquitous in modern lattice QCD calculations. Using FRR techniques, the power-counting regime (PCR) of chiral perturbation theory can be estimated. To fourth-order in the expansion at the 1% tolerance level, we find 0 (le) m π (le) 180 MeV for the PCR, extending only a small distance beyond the physical pion mass
International Nuclear Information System (INIS)
Rho, M.
1982-01-01
As an aid to discussing the structure of nucleons and nuclei conceptual framework, heuristic arguments are presented which indicate that a hadron can be considered as a bag consisting of two different phases. The chiral structure of the phase outside the bag is discussed in terms of effective field theories and it is shown to what extent experiments in nuclei can constrain the structure of such theories. Results thus obtained are then combined to set up a set of equations for the bag structure of u and d hadrons, incorporating asymptotic freedom in the phase inside of the bag confinement of quarks and gluons by boundary conditions and spontaneously broken chiral symmetry in the outside. This set of equations which represent a chirally invariant generalization of the M.I.T. bag model is then solved. (U.K.)
SIMP model at NNLO in chiral perturbation theory
DEFF Research Database (Denmark)
Hansen, Martin Rasmus Lundquist; Langaeble, K.; Sannino, F.
2015-01-01
We investigate the phenomenological viability of a recently proposed class of composite dark matter models where the relic density is determined by 3 to 2 number-changing processes in the dark sector. Here the pions of the strongly interacting field theory constitute the dark matter particles...... with phenomenological constraints challenging the viability of the simplest realisation of the strongly interacting massive particle (SIMP) paradigm....
πK scattering in chiral perturbation theory to one loop
International Nuclear Information System (INIS)
Bernard, V.; Kaiser, N.; Strasbourg-1 Univ., 67; Meissner, U.G.
1991-01-01
We evaluate the πK scattering amplitude at next-to-leading order in the framework of chiral perturbation theory. All low-energy constants appearing in the effective lagrangian of the pseudoscalars have previously been determined. We calculate the scattering lengths of the S- and P-waves as well as the expansion parameters around the point ν triple bond (s-u)/4M K = t = 0 in the unphysical region. Furthermore, phase-shifts of the low partial ways are presented and compared to the data. In most cases, the chiral predictions are comparable to the trends set by the empirical information. For a precise comparison, however, more accurate experimental determinations of the πK scattering process at low and moderate energies would be necessary. We urge the experimenters to perform these. (orig.)
Differentiating G-inflation from string gas cosmology using the effective field theory approach
Energy Technology Data Exchange (ETDEWEB)
He, Minxi; Liu, Junyu; Lu, Shiyun; Cai, Yi-Fu [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Zhou, Siyi; Wang, Yi [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Brandenberger, Robert, E-mail: hmxz0@mail.ustc.edu.cn, E-mail: jliu2@caltech.edu, E-mail: shiyun@mail.ustc.edu.cn, E-mail: zhousiyi1@gmail.com, E-mail: yifucai@ustc.edu.cn, E-mail: phyw@ust.hk, E-mail: rhb@physics.mcgill.ca [Department of Physics, McGill University, Montréal, Quebec H3A 2T8 (Canada)
2016-12-01
A characteristic signature of String Gas Cosmology is primordial power spectra for scalar and tensor modes which are almost scale-invariant but with a red tilt for scalar modes but a blue tilt for tensor modes. This feature, however, can also be realized in the so-called G-inflation model, in which Horndeski operators are introduced which leads to a blue tensor tilt by softly breaking the Null Energy Condition. In this article we search for potential observational differences between these two cosmologies by performing detailed perturbation analyses based on the Effective Field Theory approach. Our results show that, although both two models produce blue tilted tensor perturbations, they behave differently in three aspects. Firstly, String Gas Cosmology predicts a specific consistency relation between the index of the scalar modes n {sub s} and that of tensor ones n {sub t} , which is hard to be reproduced by G-inflation. Secondly, String Gas Cosmology typically predicts non-Gaussianities which are highly suppressed on observable scales, while G-inflation gives rise to observationally large non-Gaussianities because the kinetic terms in the action become important during inflation. However, after finely tuning the model parameters of G-inflation it is possible to obtain a blue tensor spectrum and negligible non-Gaussianities with a degeneracy between the two models. This degeneracy can be broken by a third observable, namely the scale dependence of the nonlinearity parameter, which vanishes for G-inflation but has a blue tilt in the case of String Gas Cosmology. Therefore, we conclude that String Gas Cosmology is in principle observationally distinguishable from the single field inflationary cosmology, even allowing for modifications such as G-inflation.
Chiral expansion and Macdonald deformation of two-dimensional Yang-Mills theory
Kökényesi, Zoltán; Sinkovics, Annamaria; Szabo, Richard J.
2016-11-01
We derive the analog of the large $N$ Gross-Taylor holomorphic string expansion for the refinement of $q$-deformed $U(N)$ Yang-Mills theory on a compact oriented Riemann surface. The derivation combines Schur-Weyl duality for quantum groups with the Etingof-Kirillov theory of generalized quantum characters which are related to Macdonald polynomials. In the unrefined limit we reproduce the chiral expansion of $q$-deformed Yang-Mills theory derived by de Haro, Ramgoolam and Torrielli. In the classical limit $q=1$, the expansion defines a new $\\beta$-deformation of Hurwitz theory wherein the refined partition function is a generating function for certain parameterized Euler characters, which reduce in the unrefined limit $\\beta=1$ to the orbifold Euler characteristics of Hurwitz spaces of holomorphic maps. We discuss the geometrical meaning of our expansions in relation to quantum spectral curves and $\\beta$-ensembles of matrix models arising in refined topological string theory.
Directory of Open Access Journals (Sweden)
Oller J.A.
2010-04-01
Full Text Available We review on a novel chiral power counting scheme for in-medium chiral perturbation theory with nucleons and pions as degrees of freedom. It allows for a systematic expansion taking into account local as well as pion-mediated inter-nucleon interactions. Based on this power counting, one can identify classes of nonperturbative diagrams that require a resummation. As a method for performing those resummations we review on the techniques of Unitary Chiral Pertubation Theory for nucleon-nucleon interactions. We then apply both power counting and non-perturbative methods to the example of calculating the pion self-energy in asymmetric nuclear matter up-to-and-including next-to-leading order. It is shown that the leading corrections involving in-medium nucleon-nucleon interactions cancel between each other at given chiral orders.
Indecomposability parameters in chiral logarithmic conformal field theory
International Nuclear Information System (INIS)
Vasseur, Romain; Jacobsen, Jesper Lykke; Saleur, Hubert
2011-01-01
Work of the last few years has shown that the key algebraic features of Logarithmic Conformal Field Theories (LCFTs) are already present in some finite lattice systems (such as the XXZ spin-1/2 chain) before the continuum limit is taken. This has provided a very convenient way to analyze the structure of indecomposable Virasoro modules and to obtain fusion rules for a variety of models such as (boundary) percolation etc. LCFTs allow for additional quantum numbers describing the fine structure of the indecomposable modules, and generalizing the 'b-number' introduced initially by Gurarie for the c=0 case. The determination of these indecomposability parameters (or logarithmic couplings) has given rise to a lot of algebraic work, but their physical meaning has remained somewhat elusive. In a recent paper, a way to measure b for boundary percolation and polymers was proposed. We generalize this work here by devising a general strategy to compute matrix elements of Virasoro generators from the numerical analysis of lattice models and their continuum limit. The method is applied to XXZ spin-1/2 and spin-1 chains with open (free) boundary conditions. They are related to gl(n+m|m) and osp(n+2m|2m)-invariant superspin chains and to non-linear sigma models with supercoset target spaces. These models can also be formulated in terms of dense and dilute loop gas. We check the method in many cases where the results were already known analytically. Furthermore, we also confront our findings with a construction generalizing Gurarie's, where logarithms emerge naturally in operator product expansions to compensate for apparently divergent terms. This argument actually allows us to compute indecomposability parameters in any logarithmic theory. A central result of our study is the construction of a Kac table for the indecomposability parameters of the logarithmic minimal models LM(1,p) and LM(p,p+1).
International Nuclear Information System (INIS)
Ertas, Mehmet; Keskin, Mustafa; Deviren, Bayram
2010-01-01
The dynamic phase transitions are studied in the spin-2 Ising model under a time-dependent oscillating magnetic field by using the effective-field theory with correlations. The effective-field dynamic equation is derived by employing the Glauber transition rates and the phases in the system are obtained by solving this dynamic equation. The nature (first- or second-order) of the dynamic phase transition is characterized by investigating the thermal behavior of the dynamic order parameter and the dynamic phase transition temperatures are obtained. The dynamic phase diagrams are presented in (T/zJ, h/zJ) plane.
Hadronic Lorentz violation in chiral perturbation theory including the coupling to external fields
Kamand, Rasha; Altschul, Brett; Schindler, Matthias R.
2018-05-01
If any violation of Lorentz symmetry exists in the hadron sector, its ultimate origins must lie at the quark level. We continue the analysis of how the theories at these two levels are connected, using chiral perturbation theory. Considering a 2-flavor quark theory, with dimension-4 operators that break Lorentz symmetry, we derive a low-energy theory of pions and nucleons that is invariant under local chiral transformations and includes the coupling to external fields. The pure meson and baryon sectors, as well as the couplings between them and the couplings to external electromagnetic and weak gauge fields, contain forms of Lorentz violation which depend on linear combinations of quark-level coefficients. In particular, at leading order the electromagnetic couplings depend on the very same combinations as appear in the free particle propagators. This means that observations of electromagnetic processes involving hadrons—such as vacuum Cerenkov radiation, which may be allowed in Lorentz-violating theories—can only reliably constrain certain particular combinations of quark coefficients.
Matrix elements of Δ B =0 operators in heavy hadron chiral perturbation theory
Lee, Jong-Wan
2015-05-01
We study the light-quark mass and spatial volume dependence of the matrix elements of Δ B =0 four-quark operators relevant for the determination of Vu b and the lifetime ratios of single-b hadrons. To this end, one-loop diagrams are computed in the framework of heavy hadron chiral perturbation theory with partially quenched formalism for three light-quark flavors in the isospin limit; flavor-connected and -disconnected diagrams are carefully analyzed. These calculations include the leading light-quark flavor and heavy-quark spin symmetry breaking effects in the heavy hadron spectrum. Our results can be used in the chiral extrapolation of lattice calculations of the matrix elements to the physical light-quark masses and to infinite volume. To provide insight on such chiral extrapolation, we evaluate the one-loop contributions to the matrix elements containing external Bd, Bs mesons and Λb baryon in the QCD limit, where sea and valence quark masses become equal. In particular, we find that the matrix elements of the λ3 flavor-octet operators with an external Bd meson receive the contributions solely from connected diagrams in which current lattice techniques are capable of precise determination of the matrix elements. Finite volume effects are at most a few percent for typical lattice sizes and pion masses.
On the value and origin of the chiral condensate in quenched SU(2) lattice gauge theory
International Nuclear Information System (INIS)
Hands, S.J.; Teper, M.; Oxford Univ.
1990-01-01
We present results of a numerical calculation of the chiral condensate in quenched SU(2) lattice gauge theory. The calculation proceeds by evaluating the spectral density distribution function for small eigenvalues on both the original lattice and after a factor-of-two blocking. It is performed on lattices as large as 20 4 and for couplings as small as β=4/g 2 =2.6. The fitted values of the condensate as a function of β show good evidence for scaling and universality when compared with string tension measurements at the same value. At the smallest lattice spacings considered, we find evidence that a separation of length scales between ultraviolet fluctuations and those responsible for chiral symmetry breaking has occurred. A more qualitative study yields a significant correlation between the small modes vertical stroken> responsible for the non-zero value of and topological activity as revealed by the expectation value 5 x1/n(>, and hence provides evidence for a topological origin of chiral symmetry breaking. Our interpretation is supported by a subsidiary calculation of the topological susceptibility of the vacuum. (orig.)
An analytic analysis of the pion decay constant in three-flavoured chiral perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Ananthanarayan, B.; Ghosh, Shayan [Indian Institute of Science, Centre for High Energy Physics, Bangalore, Karnataka (India); Bijnens, Johan [Lund University, Department of Astronomy and Theoretical Physics, Lund (Sweden)
2017-07-15
A representation of the two-loop contribution to the pion decay constant in SU(3) chiral perturbation theory is presented. The result is analytic up to the contribution of the three (different) mass sunset integrals, for which an expansion in their external momentum has been taken. We also give an analytic expression for the two-loop contribution to the pion mass based on a renormalized representation and in terms of the physical eta mass. We find an expansion of F{sub π} and M{sub π}{sup 2} in the strange-quark mass in the isospin limit, and we perform the matching of the chiral SU(2) and SU(3) low-energy constants. A numerical analysis demonstrates the high accuracy of our representation, and the strong dependence of the pion decay constant upon the values of the low-energy constants, especially in the chiral limit. Finally, we present a simplified representation that is particularly suitable for fitting with available lattice data. (orig.)
Renormalization (and power counting) of effective field theories for the nuclear force
International Nuclear Information System (INIS)
Timoteo, Varese S.; Szpigel, Sergio; Duraes, Francisco O.
2011-01-01
The most common scheme used to regularize the Lippman-Schwinger (LS) equation is to introduce a sharp or smooth regularizing function that suppresses the contributions from the potential matrix elements for momenta larger than a given cutoff scale, which separates high-energy/short-distance scales and low-energy/long-distance scales, thus eliminating the ultraviolet divergences in the momentum integrals. Then, one needs determine the strengths of the contact interactions, the so called low-energy constants (LEC), by fitting a set of low-energy scattering data. Once the LECs are fixed for a given cutoff, the LS equation can be solved to evaluate other observables. Such a procedure, motivated by Wilsons renormalization group, relies on the fundamental premise of EFT that physics at low-energy/long-distance scales is insensitive with respect to the details of the dynamics at high-energy/short-distance scales, i.e. the relevant high-energy/short- distance effects for describing the low-energy observables can be captured in the cutoff-dependent LECs. The NN interaction can be considered properly renormalized when the calculated observables are independent of the cutoff scale within the range of validity of the ChEFT or involves a small residual cutoff dependence due to the truncation of the chiral expansion. In the language of Wilsons renormalization group, this means that the LECs must run with the cutoff scale in such a way that the scattering amplitude becomes renormalization group invariant (RGI). Here we consider pionless EFT up to NNLO and chiral EFT up to NNLO and use a subtractive renormalization scheme to describe the NN scattering channels with. We fix the strength of the contact interactions at a reference scale, chosen to be the one the provides the best fit, and then evolve the driving terms with a non-relativistic Callan-Symanzik equation to slide the renormalization scale. By computing phase shift relative differences, we show that the method is RGI. We
Effective field theories of QCD for heavy quarkonia at finite temperature
International Nuclear Information System (INIS)
Ghiglieri, Jacopo
2011-01-01
Quarkonia, i.e. heavy quark-antiquark bound states, represent one of the most important probes in the experimental investigation, through heavy-ion collisions, of the high-temperature region of the phase diagram of QCD, where the onset of a deconfined medium, the quark-gluon plasma, is expected. Such bound states were hypothesized to dissociate in this plasma due to the screening of the colour charges and experimental data from SPS, RHIC and very recently also LHC indeed show a suppression pattern. In this thesis we extend the well-established and successful zero temperature framework of Non-Relativistic (NR) Effective Field Theories (EFTs) (NRQCD, pNRQCD) for the study of heavy quarkonia (production, spectroscopy, decays,..) to finite temperatures. This is achieved by integrating out in sequence the scales that characterize a NR bound state and those that are typical of a thermal medium, in the possible hierarchies that are relevant for quarkonia in the quark-gluon plasma. Within this framework we show how the potential that governs the evolution of the quark-antiquark pair is derived from QCD in a modern and rigorous way, thereby bridging the gap between phenomenological potential models and QCD. We show how the EFTs can be systematically improved and how effects that cannot be encoded in a potential arise naturally in the EFT, giving rise to new mechanisms of dissociation. We use this EFT framework to compute the spectrum and width of quarkonia in a particular setting that is relevant for the phenomenology of the ground states of bottomonium at the LHC. We also analyze within this framework the correlator of Polyakov loops, which is related to the thermodynamical free energy of heavy quark-antiquark pairs in the medium. As such, lattice computations thereof were frequently used as input for potential models. With our approach we are able to clarify the relation between these free energies and the real-time potential describing the dynamics of quarkonia, finding
Analysis of 'new physics' in the flavor sector using effective field theory methods
International Nuclear Information System (INIS)
Dassinger, Benjamin M.
2010-01-01
The enormous amount of data collected by the B factories as well as the perspective concerning the upcoming experiments at the LHC provide us with the opportunity to perform high precision tests of the standard model. This dissertation presents two model independent precision tests of the weak sector of the standard model using extensions of the weak currents which are set up using effective field theory methods in order to control the size of the different contributions. Constraints on the coefficients of the terms can then be obtained by comparison with experimental results. The first analysis incorporates a test of the lefthandedness of the weak interaction in the quark sector. By introducing additional weak couplings the differential and total decay rates of the inclusive semileptonic decay anti B → X c l anti ν l are calculated. The calculation includes the computation of the heavy-quark expansion which describes the interaction of the decaying b quark with respect to the background field of the B meson, up to order 1/m b 4 . This has been done in a new, systematic way which does not involve the calculation of gluon matrix elements. Furthermore, radiative corrections have been included up to order O(α s ) including renormalization group running. The second part deals with the introduction of lepton flavor violating operators in the context of leptonic τ decays. These operators give rise to the effective four-fermion vertex τ→ll ' l'' as well as the subsequent radiative decay τ→lγ * →ll '+ l '- . The resulting Dalitz distributions turn out to predict completely different signatures for the radiative and the effective four-fermion vertices and provide the opportunity to check, whether the decay is induced either by a radiative or by an effective four-fermion vertex. Since different models which contain lepton flavor violation are normally more sensitive to one of those decay modes than to the other, the analysis therefore allows the comparison of
Analysis of ''new physics'' in the flavor sector using effective field theory methods
Energy Technology Data Exchange (ETDEWEB)
Dassinger, Benjamin M
2010-02-05
The enormous amount of data collected by the B factories as well as the perspective concerning the upcoming experiments at the LHC provide us with the opportunity to perform high precision tests of the standard model. This dissertation presents two model independent precision tests of the weak sector of the standard model using extensions of the weak currents which are set up using effective field theory methods in order to control the size of the different contributions. Constraints on the coefficients of the terms can then be obtained by comparison with experimental results. The first analysis incorporates a test of the lefthandedness of the weak interaction in the quark sector. By introducing additional weak couplings the differential and total decay rates of the inclusive semileptonic decay anti B {yields} X{sub c}l anti {nu}{sub l} are calculated. The calculation includes the computation of the heavy-quark expansion which describes the interaction of the decaying b quark with respect to the background field of the B meson, up to order 1/m{sub b}{sup 4}. This has been done in a new, systematic way which does not involve the calculation of gluon matrix elements. Furthermore, radiative corrections have been included up to order O({alpha}{sub s}) including renormalization group running. The second part deals with the introduction of lepton flavor violating operators in the context of leptonic {tau} decays. These operators give rise to the effective four-fermion vertex {tau}{yields}ll{sup '}l'' as well as the subsequent radiative decay {tau}{yields}l{gamma}{sup *}{yields}ll{sup '+}l{sup '-}. The resulting Dalitz distributions turn out to predict completely different signatures for the radiative and the effective four-fermion vertices and provide the opportunity to check, whether the decay is induced either by a radiative or by an effective four-fermion vertex. Since different models which contain lepton flavor violation are normally more sensitive to one of those
Effective field theories of QCD for heavy quarkonia at finite temperature
Energy Technology Data Exchange (ETDEWEB)
Ghiglieri, Jacopo
2011-07-27
Quarkonia, i.e. heavy quark-antiquark bound states, represent one of the most important probes in the experimental investigation, through heavy-ion collisions, of the high-temperature region of the phase diagram of QCD, where the onset of a deconfined medium, the quark-gluon plasma, is expected. Such bound states were hypothesized to dissociate in this plasma due to the screening of the colour charges and experimental data from SPS, RHIC and very recently also LHC indeed show a suppression pattern. In this thesis we extend the well-established and successful zero temperature framework of Non-Relativistic (NR) Effective Field Theories (EFTs) (NRQCD, pNRQCD) for the study of heavy quarkonia (production, spectroscopy, decays,..) to finite temperatures. This is achieved by integrating out in sequence the scales that characterize a NR bound state and those that are typical of a thermal medium, in the possible hierarchies that are relevant for quarkonia in the quark-gluon plasma. Within this framework we show how the potential that governs the evolution of the quark-antiquark pair is derived from QCD in a modern and rigorous way, thereby bridging the gap between phenomenological potential models and QCD. We show how the EFTs can be systematically improved and how effects that cannot be encoded in a potential arise naturally in the EFT, giving rise to new mechanisms of dissociation. We use this EFT framework to compute the spectrum and width of quarkonia in a particular setting that is relevant for the phenomenology of the ground states of bottomonium at the LHC. We also analyze within this framework the correlator of Polyakov loops, which is related to the thermodynamical free energy of heavy quark-antiquark pairs in the medium. As such, lattice computations thereof were frequently used as input for potential models. With our approach we are able to clarify the relation between these free energies and the real-time potential describing the dynamics of quarkonia, finding
Preface to the Special Issue: Chiral Symmetry in Hadrons and Nuclei
International Nuclear Information System (INIS)
Geng, Lisheng; Meng, Jie; Zhao, Qiang; Zou, Bingsong
2014-01-01
The recent past years have seen a remarkable progress towards a unified description of nonperturbative strong interaction phenomena based on the fundamental theory of the strong interaction, quantum chromodynamics, and effective field theories. The papers collected in this special issue focus on the recent progress in hadron and nuclear physics related to the chiral symmetry. They are written based on presentations at the Seventh International Symposium on Chiral Symmetry in Hadron and Nuclei which took place at Beihang University, Beijing, 27-30 October 2013. The sub-topics discussed in these papers include chiral and heavy-quark spin symmetry; chiral dynamics of few-body hadron systems; chiral symmetry and hadrons in a nuclear medium; chiral dynamics in nucleon-nucleon interaction and atomic nuclei; chiral symmetry in rotating nuclei; hadron structure and interactions; exotic hadrons, heavy flavor hadrons and nuclei; mesonic atoms and nuclei
Effective field theory approach to parton-hadron conversion in high energy QCD processes
Kinder-Geiger, Klaus
1995-01-01
A QCD based effective action is constructed to describe the dynamics of confinement and symmetry breaking in the process of parton-hadron conversion. The deconfined quark and gluon degrees of freedom of the perturbative QCD vacuum are coupled to color singlet collective fields representing the non-perturbative vacuum with broken scale and chiral symmetry. The effective action recovers QCD with its scale and chiral symmetry properties at short space-time distances, but yields at large distances (r > 1 fm) to the formation of symmetry breaking gluon and quark condensates. The approach is applied to the evolution of a fragmenting q\\bar q pair with its generated gluon distribution, starting from a large hard scale Q^2. The modification of the gluon distribution arising from the coupling to the non-perturbative collective field results eventually in a complete condensation of gluons. Color flux tube configurations of the gluons in between the q\\bar q pair are obtained as solutions of the equations of motion. With ...
A note on the algebraic evaluation of correlators in local chiral conformal field theory
International Nuclear Information System (INIS)
Honecker, A.
1992-09-01
We comment on a program designed for the study of local chiral algebras and their representations in 2D conformal field theory. Based on the algebraic approach described by W. Nahm, this program efficiently calculates arbitrary n-point functions of these algebras. The program is designed such that calculations involving e.g. current algebras, W-algebras and N-Superconformal algebras can be performed. As a non-trivial application we construct an extension of the Virasoro algebra by two fields with spin four and six using the N=1-Super-Virasoro algebra. (orig.)
T-odd correlations in radiative K+l3 decays and chiral perturbation theory
International Nuclear Information System (INIS)
Mueller, E.H.; Kubis, B.; Meissner, U.G.
2006-01-01
The charged kaon decay channel K + l3γ allows for studies of direct CP violation, possibly due to non-standard mechanisms, with the help of T-odd correlation variables. In order to be able to extract a CP-violating signal from experiment, it is necessary to understand all possible standard model phases that also produce T-odd asymmetries. We complement earlier studies by considering strong interaction phases in hadronic structure functions that appear at higher orders in chiral perturbation theory, and we compare our findings to other potential sources of asymmetries. (orig.)
Leading SU(3)-breaking corrections to the baryon magnetic moments in chiral perturbation theory.
Geng, L S; Camalich, J Martin; Alvarez-Ruso, L; Vacas, M J Vicente
2008-11-28
We calculate the baryon magnetic moments using covariant chiral perturbation theory (chiPT) within the extended-on-mass-shell renormalization scheme. By fitting the two available low-energy constants, we improve the Coleman-Glashow description of the data when we include the leading SU(3)-breaking effects coming from the lowest-order loops. This success is in dramatic contrast with previous attempts at the same order using heavy-baryon chiPT and covariant infrared chiPT. We also analyze the source of this improvement with particular attention to the comparison between the covariant results.
Low energy pion-pion phase shifts from chiral perturbation theory
International Nuclear Information System (INIS)
Borges, J. Sa; Barbosa, J. Soares; Oguri, V.
1997-01-01
The low energy pion-pion S- and P- experimental phase-shifts are fitted with chiral perturbation theory (Ch PT) amplitude. The low energy pion-pion S- and P- experimental phase-shifts. The parameters l 1 and l 2 of the one loop corrected amplitude are fixed and the corresponding values of the scattering lengths are calculated. We propose that the present method is the best way to fix Ch P T parameters. The unitarization program of current algebra is also discussed. (author)
Rho, Mannque
2008-01-01
This is the sequel to the first volume to treat in one effective field theory framework the physics of strongly interacting matter under extreme conditions. This is vital for understanding the high temperature phenomena taking place in relativistic heavy ion collisions and in the early Universe, as well as the high-density matter predicted to be present in compact stars. The underlying thesis is that what governs hadronic properties in a heat bath and/or a dense medium is hidden local symmetry which emerges from chiral dynamics of light quark systems and from the duality between QCD in 4D and
Spontaneous symmetry breaking and fermion chirality in higher-dimensional gauge theory
International Nuclear Information System (INIS)
Wetterich, C.
1985-01-01
The number of chiral fermions may change in the course of spontaneous symmetry breaking. We discuss solutions of a six-dimensional Einstein-Yang-Mills theory based on SO(12). In the resulting effective four-dimensional theory they can be interpreted as spontaneous breaking of a gauge group SO(10) to H=SU(3)sub(C)xSU(2)sub(L)xU(1)sub(R)xU(1)sub(B-L). For all solutions, the fermions which are chiral with respect to H form standard generations. However, the number of generations for the solutions with broken SO(10) may be different compared to the symmetric solutions. All solutions considered here exhibit a local generation group SU(2)sub(G)xU(1)sub(G). For the solutions with broken SO(10) symmetry, the leptons and quarks within one generation transform differently with respect to SU(2)sub(G)xU(1)sub(G). Spontaneous symmetry breaking also modifies the SO(10) relations among Yukawa couplings. All this has important consequences for possible fermion mass relations obtained from higher-dimensional theories. (orig.)
Ahmed, Mohammad W.; Gao, Haiyan; Weller, Henry R.; Holstein, Barry
2007-10-01
pt. A. Plenary session. Opening remarks: experimental tests of chiral symmetry breaking / A. M. Bernstein. [Double pie symbols] scattering / H. Leutwyler. Chiral effective field theory in a [Triangle]-resonance region / V. Pascalutsa. Some recent developments in chiral perturbation theory / Ulf-G. Mei ner. Chiral extrapolation and nucleon structure from the lattice / R.D. Young. Recent results from HAPPEX / R. Michaels. Chiral symmetries and low energy searches for new physics / M.J. Ramsey-Musolf. Kaon physics: recent experimental progress / M. Moulson. Status of the Cabibbo angle / V. Cirigliano. Lattice QCD and nucleon spin structure / J.W. Negele. Spin sum rules and polarizabilities: results from Jefferson lab / J-P Chen. Compton scattering and nucleon polarisabilities / Judith A. McGovern. Virtual compton scattering at MIT-bates / R. Miskimen. Physics results from the BLAST detector at the BATES accelerator / R.P. Redwine. The [Pie sympbol]NN system, recent progress / C. Hanhart. Application of chiral nuclear forces to light nuclei / A. Nogga. New results on few-body experiments at low energy / Y. Nagai. Few-body lattice calculations / M.J. Savage. Research opportunities at the upgraded HI?S facility / H.R. Weller -- pt. B. Goldstone boson dynamics. Working group summary: Goldstone Boson dynamics / G. Colangelo and S. Giovannella. Recent results on radiative Kaon decays from NA48 and NA48/2 / S.G. López. Cusps in K-->3 [Pie symbol] decays / B. Kubis. Recent KTeV results on radiative Kaon decays / M.C. Ronquest. The [Double pie symbols] scattering amplitude / J.R. Peláez. Determination of the Regge parameters in the [Double pie symbols] scattering amplitude / I. Caprini. e+e- Hadronic cross section measurement at DA[symbol]NE with the KLOE detector / P. Beltrame. Measurement of the form factors of e+e- -->2([Pie symbol]+[Pie symbol]-), pp and the resonant parameters of the heavy charmonia at BES / H. Hu. Measurement of e+e- multihadronic cross section below 4
Energy Technology Data Exchange (ETDEWEB)
Cohen, T.D.
1998-04-01
The physics goals of the effective field theory program for nuclear phenomena are outlined. It is pointed out that there are multiple schemes for implementing EFT and it is presently not clear if any of these schemes is viable. Most of the applications of effective field theory ideas have been on nucleon-nucleon scattering. It is argued that this is little more than curve fitting and that other quantities need to be calculated to test the ideas. It is shown that EFT methods work well for certain bound state properties of the deuteron electric form factor. However, it is also shown that this success depends sensitively on the fact that the majority of the probability of the deuteron`s wave function is beyond the range of the potential. This circumstance is special to the deuteron suggesting that it will be very difficult to achieve the same kinds of success for tightly bound nuclei.
Chauhan, B.; Kumar, S.; Malik, R. P.
2018-02-01
We derive the off-shell nilpotent (fermionic) (anti-)BRST symmetry transformations by exploiting the (anti-)chiral superfield approach (ACSA) to Becchi-Rouet-Stora-Tyutin (BRST) formalism for the interacting Abelian 1-form gauge theories where there is a coupling between the U(1) Abelian 1-form gauge field and Dirac as well as complex scalar fields. We exploit the (anti-)BRST invariant restrictions on the (anti-)chiral superfields to derive the fermionic symmetries of our present D-dimensional Abelian 1-form gauge theories. The novel observation of our present investigation is the derivation of the absolute anticommutativity of the nilpotent (anti-)BRST charges despite the fact that our ordinary D-dimensional theories are generalized onto the (D,1)-dimensional (anti-) chiral super-submanifolds (of the general (D,2)-dimensional supermanifold) where only the (anti-)chiral super expansions of the (anti-)chiral superfields have been taken into account. We also discuss the nilpotency of the (anti-)BRST charges and (anti-)BRST invariance of the Lagrangian densities of our present theories within the framework of ACSA to BRST formalism.
Kallin, Catherine; Berlinsky, John
2016-05-01
Chiral superconductivity is a striking quantum phenomenon in which an unconventional superconductor spontaneously develops an angular momentum and lowers its free energy by eliminating nodes in the gap. It is a topologically non-trivial state and, as such, exhibits distinctive topological modes at surfaces and defects. In this paper we discuss the current theory and experimental results on chiral superconductors, focusing on two of the best-studied systems, Sr2RuO4, which is thought to be a chiral triplet p-wave superconductor, and UPt3, which has two low-temperature superconducting phases (in zero magnetic field), the lower of which is believed to be chiral triplet f-wave. Other systems that may exhibit chiral superconductivity are also discussed. Key signatures of chiral superconductivity are surface currents and chiral Majorana modes, Majorana states in vortex cores, and the possibility of half-flux quantum vortices in the case of triplet pairing. Experimental evidence for chiral superconductivity from μSR, NMR, strain, polar Kerr effect and Josephson tunneling experiments are discussed.
International Nuclear Information System (INIS)
Geng, L. S.; Camalich, J. Martin; Vacas, M. J. Vicente
2009-01-01
We present a calculation of the leading SU(3)-breaking O(p 3 ) corrections to the electromagnetic moments and charge radius of the lowest-lying decuplet resonances in covariant chiral perturbation theory. In particular, the magnetic dipole moment of the members of the decuplet is predicted fixing the only low-energy constant (LEC) present up to this order with the well-measured magnetic dipole moment of the Ω - . We predict μ Δ ++ =6.04(13) and μ Δ + =2.84(2), which agree well with the current experimental information. For the electric quadrupole moment and the charge radius, we use state-of-the-art lattice QCD results to determine the corresponding LECs, whereas for the magnetic octupole moment there is no unknown LEC up to the order considered here, and we obtain a pure prediction. We compare our results with those reported in large N c , lattice QCD, heavy-baryon chiral perturbation theory, and other models.
International Nuclear Information System (INIS)
Bernard, V.; Kubis, B.; Meissner, U.G.
2005-01-01
We analyze the Fubini-Furlan-Rosetti sum rule in the framework of covariant baryon chiral perturbation theory to leading one-loop accuracy and including next-to-leading-order polynomial contributions. We discuss the relation between the subtraction constants in the invariant amplitudes and certain low-energy constants employed in earlier chiral perturbation theory studies of threshold neutral pion photoproduction off nucleons. In particular, we consider the corrections to the sum rule due to the finite pion mass and show that below the threshold they agree well with determinations based on fixed-t dispersion relations. We also discuss the energy dependence of the electric dipole amplitude E 0+ . (orig.)
Nonrelativistic effective field theories of QED and QCD. Applications and automatic calculations
Energy Technology Data Exchange (ETDEWEB)
Shtabovenko, Vladyslav
2017-05-22
This thesis deals with the applications of nonrelativistic Effective Field Theories to electromagnetic and strong interactions. The main results of this work are divided into three parts. In the first part, we use potential Nonrelativistic Quantum Electrodynamics (pNRQED), an EFT of QED at energies much below m{sub e}α (with m{sub e} being the electron mass and α the fine-structure constant), to develop a consistent description of electromagnetic van der Waals forces between two hydrogen atoms at a separation R much larger than the Bohr radius. We consider the interactions at short (R<<1/m{sub e}α{sup 2}), long (R>>1/m{sub e}α{sup 2}) and intermediate (R∝1/m{sub e}α{sup 2}) distances and identify the relevant dynamical scales that characterize each of the three regimes. For each regime we construct a suitable van der Waals EFT, that provides the simplest description of the low-energy dynamics. In this framework, van der Waals potentials naturally arise from the matching coefficients of the corresponding EFTs. They can be computed in a systematic way, order by order in the relevant expansion parameters, as is done in this work. Furthermore, the potentials receive contributions from radiative corrections and have to be renormalized. The development of a consistent EFT framework to treat electromagnetic van der Waals interactions between hydrogen atoms and the renormalization of the corresponding van der Waals potentials are the novel features of this study. In the second part, we study relativistic O(α{sup 0}{sub s}υ{sup 2}) (with α{sub s} being the strong coupling constant) corrections to the exclusive electromagnetic production of the heavy quarkonium χ {sub cJ} and a hard photon in the framework of nonrelativistic Quantum Chromodynamics (NRQCD), an EFT of QCD that takes full advantage of the nonrelativistic nature of charmonia and bottomonia and exploits wide separation of the relevant dynamical scales. These scales are m{sub Q} >> m{sub Q}υ >> m{sub Q
Nonrelativistic effective field theories of QED and QCD. Applications and automatic calculations
International Nuclear Information System (INIS)
Shtabovenko, Vladyslav
2017-01-01
This thesis deals with the applications of nonrelativistic Effective Field Theories to electromagnetic and strong interactions. The main results of this work are divided into three parts. In the first part, we use potential Nonrelativistic Quantum Electrodynamics (pNRQED), an EFT of QED at energies much below m e α (with m e being the electron mass and α the fine-structure constant), to develop a consistent description of electromagnetic van der Waals forces between two hydrogen atoms at a separation R much larger than the Bohr radius. We consider the interactions at short (R<<1/m e α 2 ), long (R>>1/m e α 2 ) and intermediate (R∝1/m e α 2 ) distances and identify the relevant dynamical scales that characterize each of the three regimes. For each regime we construct a suitable van der Waals EFT, that provides the simplest description of the low-energy dynamics. In this framework, van der Waals potentials naturally arise from the matching coefficients of the corresponding EFTs. They can be computed in a systematic way, order by order in the relevant expansion parameters, as is done in this work. Furthermore, the potentials receive contributions from radiative corrections and have to be renormalized. The development of a consistent EFT framework to treat electromagnetic van der Waals interactions between hydrogen atoms and the renormalization of the corresponding van der Waals potentials are the novel features of this study. In the second part, we study relativistic O(α 0 s υ 2 ) (with α s being the strong coupling constant) corrections to the exclusive electromagnetic production of the heavy quarkonium χ cJ and a hard photon in the framework of nonrelativistic Quantum Chromodynamics (NRQCD), an EFT of QCD that takes full advantage of the nonrelativistic nature of charmonia and bottomonia and exploits wide separation of the relevant dynamical scales. These scales are m Q >> m Q υ >> m Q υ 2 , where m Q is the heavy quark mass and υ is the relative
Chiral symmetry and chiral-symmetry breaking
International Nuclear Information System (INIS)
Peskin, M.E.
1982-12-01
These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed
New predictions for generalized spin polarizabilities from heavy baryon chiral perturbation theory
International Nuclear Information System (INIS)
Chung-Wen Kao; Barbara Pasquini; Marc Vanderhaeghen
2004-01-01
We extract the next-to-next-to-leading order results for spin-flip generalized polarizabilities (GPs) of the nucleon from the spin-dependent amplitudes for virtual Compton scattering (VCS) at Ο(p 4 ) in heavy baryon chiral perturbation theory. At this order, no unknown low energy constants enter the theory, allowing us to make absolute predictions for all spin-flip GPs. Furthermore, by using constraint equations between the GPs due to nucleon crossing combined with charge conjugation symmetry of the VCS amplitudes, we get a next-to-next-to-next-to-leading order prediction for one of the GPs. We provide estimates for forthcoming double polarization experiments which allow to access these spin-flip GPs of the nucleon
Multiple exciton generation in chiral carbon nanotubes: Density functional theory based computation
Kryjevski, Andrei; Mihaylov, Deyan; Kilina, Svetlana; Kilin, Dmitri
2017-10-01
We use a Boltzmann transport equation (BE) to study time evolution of a photo-excited state in a nanoparticle including phonon-mediated exciton relaxation and the multiple exciton generation (MEG) processes, such as exciton-to-biexciton multiplication and biexciton-to-exciton recombination. BE collision integrals are computed using Kadanoff-Baym-Keldysh many-body perturbation theory based on density functional theory simulations, including exciton effects. We compute internal quantum efficiency (QE), which is the number of excitons generated from an absorbed photon in the course of the relaxation. We apply this approach to chiral single-wall carbon nanotubes (SWCNTs), such as (6,2) and (6,5). We predict efficient MEG in the (6,2) and (6,5) SWCNTs within the solar spectrum range starting at the 2Eg energy threshold and with QE reaching ˜1.6 at about 3Eg, where Eg is the electronic gap.
Energy Technology Data Exchange (ETDEWEB)
Deviren, Bayram [Department of Physics, Nevsehir University, 50300 Nevsehir (Turkey); Institute of Science, Erciyes University, 38039 Kayseri (Turkey); Keskin, Mustafa, E-mail: keskin@erciyes.edu.t [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)
2010-07-12
Dynamic aspects of a two-sublattice Ising metamagnet on honeycomb, square and hexagonal lattices under the presence of a time-dependent oscillating external magnetic field are studied by using the effective-field theory with correlations. The set of effective-field dynamic equations is derived by employing Glauber transition rates. The phases in the system are obtained by solving these dynamic equations. The thermal behavior of the dynamic staggered magnetization, the hysteresis loop area and correlation are investigated in order to characterize the nature of the dynamic transitions and to obtain dynamic phase transition temperatures. The phase diagrams are constructed in two different planes, and exhibit dynamic tricritical behavior, which strongly depends on interaction parameters. In order to investigate the spin correlation effect on the dynamic phase diagrams of the system, the results are also given within the framework of the dynamic mean-field approximation.
International Nuclear Information System (INIS)
Deviren, Bayram; Keskin, Mustafa
2010-01-01
Dynamic aspects of a two-sublattice Ising metamagnet on honeycomb, square and hexagonal lattices under the presence of a time-dependent oscillating external magnetic field are studied by using the effective-field theory with correlations. The set of effective-field dynamic equations is derived by employing Glauber transition rates. The phases in the system are obtained by solving these dynamic equations. The thermal behavior of the dynamic staggered magnetization, the hysteresis loop area and correlation are investigated in order to characterize the nature of the dynamic transitions and to obtain dynamic phase transition temperatures. The phase diagrams are constructed in two different planes, and exhibit dynamic tricritical behavior, which strongly depends on interaction parameters. In order to investigate the spin correlation effect on the dynamic phase diagrams of the system, the results are also given within the framework of the dynamic mean-field approximation.
Universality in random matrix theory and chiral symmetry breaking in QCD
International Nuclear Information System (INIS)
Akemann, G.
2000-05-01
In this work we review the topic of random matrix model universality with particular stress on its application to the study of chiral symmetry breaking in QCD. We highlight the role of microscopic and macroscopic matrix model correlation functions played in the description of the deep infrared eigenvalue spectrum of the Dirac operator. The universal microscopic correlation functions are presented for all three chiral symmetry breaking patterns, and the corresponding random matrix universality proofs are given for massless and massive fermions in a unified way. These analytic results have been widely confirmed from QCD lattice data and we present a comparison with the most recent analytic calculations describing data for dynamical SU(2) staggered fermions. The microscopic matrix model results are then re-expressed in terms of the finite-volume partition functions of Leutwyler and Smilga, where some of these expressions have been recently obtained using field theory only. The macroscopic random matrix universality is reviewed for the most simplest examples of bosonic and supersymmetric models. We also give an example for a non-universal deformation of a random matrix model - the restricted trace ensemble. (orig.)
International Nuclear Information System (INIS)
Bayegan, S.; Sadeghi, H.
2004-01-01
In big-bang nucleosynthesis, processes relevant ti increasing of nucleon density are more important. One of the theories that its solutions more accurately explain the experimental works is Effective Field Theory in this paper. Magnetic moment (χM1) for radiative capture of protons by deuterons p + d → 3 He+γ process is calculated using Effective Field Theory. The calculation includes coulomb interaction up to next-to -next-leading order (N 2 LO)
Energy Technology Data Exchange (ETDEWEB)
Lehnhart, B.C.
2007-05-15
This thesis is concerned with electromagnetic pion production within manifestly Lorentz-invariant chiral perturbation theory using the assumption of isospin symmetry. In a one-loop calculation up to the chiral order O(q{sup 4}), 105 Feynman diagrams contribute, consisting of 20 tree graphs and 85 loop diagrams. The tree graphs are classified as 16 pole diagrams and 4 contact graphs. Of the 85 loop diagrams, 50 diagrams are of order three and 35 diagrams are of fourth order. To calculate the pion production amplitude algorithms are developed on the basis of the Mathematica package FeynCalc. The one-photon-exchange approximation allows one to parametrise the pion production amplitude as the product of the polarisation vector of the (virtual) photon and the matrix element of the transition current. The polarisation vector is related to the leptonic vertex and the photon propagator and is well-known from QED. The dependence of the amplitude on the strong interaction is contained in the matrix element of the transition current, and we use chiral perturbation theory to describe this matrix element. The transition current can be expressed in terms of six gauge invariant amplitudes, each of which can again be decomposed into three isospin amplitudes. Linear combinations of these amplitudes allow us to describe the physical amplitudes. The one-loop integrals appearing within this calculation are determined numerically by the program LoopTools. In the case of tensorial integrals it is required to perform the method of Passarino and Veltman first. Furthermore, we apply the reformulated infrared regularisation which ensures that the results fulfill the chiral power counting. For this purpose algorithms are developed which determine the subtraction terms automatically. The obtained isospin amplitudes are integrated in the program MAID. As tests the s-wave multipoles E{sub 0+} and L{sub 0+} (using results up to chiral order O(q{sup 3})) are calculated in the threshold region
On the chiral perturbation theory for two-flavor two-color QCD at finite chemical potential
Czech Academy of Sciences Publication Activity Database
Brauner, Tomáš
2006-01-01
Roč. 21, č. 7 (2006), s. 559-569 ISSN 0217-7323 R&D Projects: GA ČR(CZ) GD202/05/H003 Institutional research plan: CEZ:AV0Z10480505 Keywords : two-color QCD * chiral perturbation theory * chemical potential Subject RIV: BE - Theoretical Physics Impact factor: 1.564, year: 2006
The electric dipole form factor of the nucleon in chiral perturbation theory to sub-leading order
Mereghetti, E.; de Vries, J.; Hockings, W. H.; Maekawa, C. M.; van Kolck, U.
2011-01-01
The electric dipole form factor (EDFF) of the nucleon stemming from the QCD (theta) over bar term and from the quark color-electric dipole moments is calculated in chiral perturbation theory to sub-leading order. This is the lowest order in which the isoscalar EDFF receives a calculable,
Effective field theory approach to structure functions at small xBj
International Nuclear Information System (INIS)
Nachtmann, O.
2003-01-01
We relate the structure functions of deep inelastic lepton-nucleon scattering to current-current correlation functions in a Euclidean field theory depending on a parameter r. The r-dependent Hamiltonian of the theory is P 0 -(1-r)P 3 , with P 0 the usual Hamiltonian and P 3 the third component of the momentum operator. We show that a small x Bj in the structure functions corresponds to the small r limit of the effective theory. We argue that for r→0 there is a critical regime of the theory where simple scaling relations should hold. We show that in this framework Regge behaviour of the structure functions obtained with the hard pomeron ansatz corresponds to a scaling behaviour of the matrix elements in the effective theory where the intercept of the hard pomeron appears as a critical index. Explicit expressions for various analytic continuations of the structure functions and matrix elements are given as well as path integral representations for the matrix elements in the effective theory. Our aim is to provide a framework for truly non-perturbative calculations of the structure functions at small x Bj for arbitrary Q 2 . (orig.)
NLO QCD effective field theory analysis of W+W- production at the LHC including fermionic operators
Baglio, Julien; Dawson, Sally; Lewis, Ian M.
2017-10-01
We study the impact of anomalous gauge boson and fermion couplings on the production of W+W- pairs at the LHC. Helicity amplitudes are presented separately to demonstrate the sources of new physics contributions and the impact of QCD and electroweak corrections. The QCD corrections have important effects on the fits to anomalous couplings, in particular when one W boson is longitudinally polarized and the other is transversely polarized. In effective field theory language, we demonstrate that the dimension-6 approximation to constraining new physics effects in W+W- pair production fails at pT˜500 - 1000 GeV .
Energy Technology Data Exchange (ETDEWEB)
Deviren, Bayram [Institute of Science, Erciyes University, Kayseri 38039 (Turkey); Canko, Osman [Department of Physics, Erciyes University, Kayseri 38039 (Turkey); Keskin, Mustafa [Department of Physics, Erciyes University, Kayseri 38039 (Turkey)], E-mail: keskin@erciyes.edu.tr
2008-09-15
The Ising model with three alternative layers on the honeycomb and square lattices is studied by using the effective-field theory with correlations. We consider that the nearest-neighbor spins of each layer are coupled ferromagnetically and the adjacent spins of the nearest-neighbor layers are coupled either ferromagnetically or anti-ferromagnetically depending on the sign of the bilinear exchange interactions. We investigate the thermal variations of the magnetizations and present the phase diagrams. The phase diagrams contain the paramagnetic, ferromagnetic and anti-ferromagnetic phases, and the system also exhibits a tricritical behavior.
International Nuclear Information System (INIS)
Deviren, Bayram; Canko, Osman; Keskin, Mustafa
2008-01-01
The Ising model with three alternative layers on the honeycomb and square lattices is studied by using the effective-field theory with correlations. We consider that the nearest-neighbor spins of each layer are coupled ferromagnetically and the adjacent spins of the nearest-neighbor layers are coupled either ferromagnetically or anti-ferromagnetically depending on the sign of the bilinear exchange interactions. We investigate the thermal variations of the magnetizations and present the phase diagrams. The phase diagrams contain the paramagnetic, ferromagnetic and anti-ferromagnetic phases, and the system also exhibits a tricritical behavior
Arani, M. Moeini; Nematollahi, H.; Mahboubi, N.; Bayegan, S.
2014-01-01
We take a new look at the neutron radiative capture by a deuteron at thermal energy with the pionless effective field theory (EFT($\\pi\\!\\!\\!/$)) approach. We present in detail the calculation of $nd\\rightarrow$ $^3H\\gamma$ amplitudes for incoming doublet and quartet channels leading to the formation of a triton fully in the projection method based on the cluster-configuration space approach. In the present work, we consider all possible one-body and two-body photon interaction diagrams. In fa...
Probing CP-violating Higgs and gauge-boson couplings in the Standard Model effective field theory
Energy Technology Data Exchange (ETDEWEB)
Ferreira, Felipe [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom); Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, Paraiba (Brazil); Fuks, Benjamin [Sorbonne Universites, Universite Pierre et Marie Curie (Paris 06), UMR 7589, LPTHE, Paris (France); CNRS, UMR 7589, LPTHE, Paris (France); Institut Universitaire de France, Paris (France); Sanz, Veronica [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom); Sengupta, Dipan [Universite Grenoble-Alpes, CNRS/IN2P3, Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France); Michigan State University, Department of Physics and Astronomy, East Lansing (United States)
2017-10-15
We study the phenomenological consequences of several CP-violating structures that could arise in the Standard Model effective field theory framework. Focusing on operators involving electroweak gauge and/or Higgs bosons, we derive constraints originating from Run I LHC data. We then study the capabilities of the present and future LHC runs at higher energies to further probe associated CP-violating phenomena and we demonstrate how differential information can play a key role. We consider both traditional four-lepton probes of CP-violation in the Higgs sector and novel new physics handles based on varied angular and non-angular observables. (orig.)
Effect of δ meson and ρ-ω cross couplings in effective field theory motivated Lagrangian approach
International Nuclear Information System (INIS)
Jagota, R.K.; Dhiman, S.K.; Sharma, B.K.; Arumugam, P.; Patra, S.K.
2005-01-01
It is shown that the self and cross couplings of ω meson plays an important role to make the nuclear equation of state (EOS) softer. The parameter set G2, obtained from the effective field theory motivated Lagrangian (E-RMF) approach, is very successful to reproduce the nuclear matter properties including the structure of neutron star as well as of finite nuclei. The motivation of the present report is to see the effects of these terms in the E-RMF Lagrangian on infinite nuclear matter as well as finite nuclei
Bijnens, Johan; Rössler, Thomas
2015-11-01
We present a calculation of the finite volume corrections to meson masses and decay constants in three flavour Partially Quenched Chiral Perturbation Theory (PQChPT) through two-loop order in the chiral expansion for the flavour-charged (or off-diagonal) pseudoscalar mesons. The analytical results are obtained for three sea quark flavours with one, two or three different masses. We reproduce the known infinite volume results and the finite volume results in the unquenched case. The calculation has been performed using the supersymmetric formulation of PQChPT as well as with a quark flow technique.
Chiral vertex operators in off-conformal theory: Sine-Gordon example
International Nuclear Information System (INIS)
Chang, S.; Rajaraman, R.
1996-01-01
We study chiral vertex operators in sine-Gordon (SG) theory, viewed as an off-conformal system. We find that these operators, which would have been primary fields in the conformal limit, have interesting properties in the SG model. Some of them commute with the cosine interaction term in the Hamiltonian at a finite separation. Their Heisenberg equations of motion are local in space. An example of such vertex operators is Mandelstam close-quote s bosonic representation of the Fermi field. Another example is a set of vertex operators of topological number 2. We show how to construct conserved nonlocal currents from these operators. In the presence of the nonconformal interactions, these nonlocal currents have unique Lorentz spins. copyright 1996 The American Physical Society
One-loop divergences in chiral perturbation theory and right-invariant metrics on SU(3)
International Nuclear Information System (INIS)
Esposito-Farese, G.
1991-01-01
In the framework of chiral perturbation theory, we compute the one-loop divergences of the effective Lagrangian describing strong and non-leptonic weak interactions of pseudoscalar mesons. We use the background field method and the heat-kernel expansion, and underline the geometrical meaning of the different terms, showing how the right-invariance of the metrics on SU(3) allows to clarify and simplify the calculations. Our results are given in terms of a minimal set of independent counterterms, and shorten previous ones of the literature, in the particular case where the electromagnetic field is the only external source which is considered. We also show that a geometrical construction of the effective Lagrangian at order O(p 4 ) allows to derive some relations between the finite parts of the coupling constants. These relations do not depend on the scale μ used to renormalize. (orig.)
Magnetic dipole moment of the Δ(1232) in chiral perturbation theory
International Nuclear Information System (INIS)
Hacker, C.; Wies, N.; Scherer, S.; Gegelia, J.
2006-01-01
The magnetic dipole moment of the Δ(1232) is calculated in the framework of manifestly Lorentz-invariant baryon chiral perturbation theory in combination with the extended on-mass-shell renormalization scheme. As in the case of the nucleon, at leading order both isoscalar and isovector anomalous magnetic moments are given in terms of two low-energy constants. In contrast to the nucleon case, at next-to-leading order the isoscalar anomalous magnetic moment receives a (real) loop contribution. Moreover, due to the unstable nature of the Δ(1232), at next-to-leading order the isovector anomalous magnetic moment not only receives a real but also an imaginary loop contribution. (orig.)
η → π0γγ to O(p6) in chiral perturbation theory
International Nuclear Information System (INIS)
Jetter, M.
1995-08-01
The decay η → π0γγ is discussed in the framework of SU(3) chiral perturbation theory. The process is dominated by the O(p 6 ) in the momentum expansion where tree-level amplitudes from the effective Lagrangian L 6 enter together with one-loop contributions from L 4 and two-loop contributions from L 2 . We estimate the 6 independent L 6 coupling constants by resonance saturation consistent with the pion production process γγ → π 0 π 0 and calculate the pion-loop part of the one-and two-loop amplitude. Predictions for the total rate and spectrum of η → π 0 γγ are given together with a discussion of the uncertainties involved. (author). 27 refs., 8 figs.,3 tabs
DEFF Research Database (Denmark)
Novitsky, Andrey; Galynsky, Vladimir M.; Zhukovsky, Sergei
2012-01-01
The electronic Lorentz theory is employed to explain the optical properties of planar split-ring metamaterials. Starting from the dynamics of individual free carriers, the electromagnetic response of an individual split-ring meta-atom is determined, and the effective permittivity tensor...... of the metamaterial is calculated for normal incidence of light. Whenever the split ring lacks in-plane mirror symmetry, the corresponding permittivity tensor has a crystallographic structure of an elliptically dichroic medium, and the metamaterial exhibits optical properties of planar chiral structures. Its...... transmission spectra are different for right-handed versus left-handed circular polarization of the incident wave, so the structure changes its transmittance when the direction of incidence is reversed. The magnitude of this change is shown to be related to the geometric parameters of the split ring...
Supersymmetry, quantum gauge anomalies and generalized Chern-Simons terms in chiral gauge theory
International Nuclear Information System (INIS)
Schmidt, Torsten
2009-01-01
The purpose of this thesis is to investigate the interplay of anomaly cancellation and generalized Chern-Simons terms in four-dimensional chiral gauge theory. We start with a detailed discussion of generalized Chern-Simons terms with the canellation of anomalies via the Green-Schwarz mechanism. With this at hand, we investigate the situation in general N=1 supersymmetric field theories with generalized Chern-Simons terms. Two simple consistency conditions are shown to encode strong constraints on the allowed anomalies for different types of gauge groups. In one major part of this thesis we are going to display to what extent one has to modify the existing formalism in order to allow for the cancellation of quantum gauge anomalies via the Green-Schwarz mechanism. At the end of this thesis we comment on a puzzle in the literature on supersymmetric field theories with massive tensor fields. The potential contains a term that does not arise from eliminating an auxiliary field. We clarify the origin of this term and display the relation to standard D-term potential. In an appendix it is explicitly shown how these low energy effective actions might be connected to the formulation of four-dimensional gauge theories discussed at earlier stages of this thesis. (orig.)
Effective-field-theory model for the fractional quantum Hall effect
International Nuclear Information System (INIS)
Zhang, S.C.; Hansson, T.H.; Kivelson, S.
1989-01-01
Starting directly from the microscopic Hamiltonian, we derive a field-theory model for the fractional quantum hall effect. By considering an approximate coarse-grained version of the same model, we construct a Landau-Ginzburg theory similar to that of Girvin. The partition function of the model exhibits cusps as a function of density and the Hall conductance is quantized at filling factors ν = (2k-1)/sup -1/ with k an arbitrary integer. At these fractions the ground state is incompressible, and the quasiparticles and quasiholes have fractional charge and obey fractional statistics. Finally, we show that the collective density fluctuations are massive
Plasma effective field theory advertised, then illustrated by e, p, H-atom gas
International Nuclear Information System (INIS)
Brown, L.S.
2001-01-01
The first part is a lightning fast overview of the application of ideas of modern effective quantum field theory (which originated in elementary particle theory) to plasma physics. An exhaustive account is presented in a long report with L. G. Yaffe which contains all the details set out in a self-contained and pedagogical fashion. The second part shows how the low temperature but dilute limit of the partition function at two-loop order describes a gas of electrons, protons, and hydrogen atoms in their ground state. Hydrogen atoms emerge automatically from the general framework which does not begin with any explicit consideration of atoms. (orig.)
Introduction to Chiral Symmetry
Energy Technology Data Exchange (ETDEWEB)
Koch, Volker [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2017-05-09
These lectures are an attempt to a pedagogical introduction into the elementary concepts of chiral symmetry in nuclear physics. We will also discuss some effective chiral models such as the linear and nonlinear sigma model as well as the essential ideas of chiral perturbation theory. We will present some applications to the physics of ultrarelativistic heavy ion collisionsd.
Introduction to chiral symmetry
International Nuclear Information System (INIS)
Koch, V.
1996-01-01
These lectures are an attempt to a pedagogical introduction into the elementary concepts of chiral symmetry in nuclear physics. Effective chiral models such as the linear and nonlinear sigma model will be discussed as well as the essential ideas of chiral perturbation theory. Some applications to the physics of ultrarelativistic heavy ion collisions will be presented
Klos, P.; Menéndez, J.; Gazit, D.; Schwenk, A.
2013-01-01
We perform state-of-the-art large-scale shell-model calculations of the structure factors for elastic spin-dependent WIMP scattering off 129,131Xe, 127I, 73Ge, 19F, 23Na, 27Al, and 29Si. This comprehensive survey covers the non-zero-spin nuclei relevant to direct dark matter detection. We include a pedagogical presentation of the formalism necessary to describe elastic and inelastic WIMP-nucleus scattering. The valence spaces and nuclear interactions employed have been previously used in nucl...
Chiral and continuum extrapolation of partially quenched lattice results
Energy Technology Data Exchange (ETDEWEB)
C.R. Allton; W. Armour; D.B. Leinweber; A.W. Thomas; R.D. Young
2005-04-01
The vector meson mass is extracted from a large sample of partially quenched, two-flavor lattice QCD simulations. For the first time, discretization, finite-volume and partial quenching artifacts are treated in a unified chiral effective field theory analysis of the lattice simulation results.
Effective spacetime understanding emergence in effective field theory and quantum gravity
Crowther, Karen
2016-01-01
This book discusses the notion that quantum gravity may represent the "breakdown" of spacetime at extremely high energy scales. If spacetime does not exist at the fundamental level, then it has to be considered "emergent", in other words an effective structure, valid at low energy scales. The author develops a conception of emergence appropriate to effective theories in physics, and shows how it applies (or could apply) in various approaches to quantum gravity, including condensed matter approaches, discrete approaches, and loop quantum gravity.
Lattice QCD at the physical point meets S U (2 ) chiral perturbation theory
Dürr, Stephan; Fodor, Zoltán; Hoelbling, Christian; Krieg, Stefan; Kurth, Thorsten; Lellouch, Laurent; Lippert, Thomas; Malak, Rehan; Métivet, Thibaut; Portelli, Antonin; Sastre, Alfonso; Szabó, Kálmán; Budapest-Marseille-Wuppertal Collaboration
2014-12-01
We perform a detailed, fully correlated study of the chiral behavior of the pion mass and decay constant, based on 2 +1 flavor lattice QCD simulations. These calculations are implemented using tree-level, O (a )-improved Wilson fermions, at four values of the lattice spacing down to 0.054 fm and all the way down to below the physical value of the pion mass. They allow a sharp comparison with the predictions of S U (2 ) chiral perturbation theory (χ PT ) and a determination of some of its low energy constants. In particular, we systematically explore the range of applicability of next-to-leading order (NLO) S U (2 ) χ PT in two different expansions: the first in quark mass (x expansion), and the second in pion mass (ξ expansion). We find that these expansions begin showing signs of failure for Mπ≳300 MeV , for the typical percent-level precision of our Nf=2 +1 lattice results. We further determine the LO low energy constants (LECs), F =88.0 ±1.3 ±0.2 and BMS ¯(2 GeV )=2.61 (6 )(1 ) GeV , and the related quark condensate, ΣMS ¯(2 GeV )=(272 ±4 ±1 MeV )3 , as well as the NLO ones, ℓ¯3=2.6 (5 )(3 ) and ℓ¯4=3.7 (4 )(2 ), with fully controlled uncertainties. We also explore the next-to-next-to-leading order (NNLO) expansions and the values of NNLO LECs. In addition, we show that the lattice results favor the presence of chiral logarithms. We further demonstrate how the absence of lattice results with pion masses below 200 MeV can lead to misleading results and conclusions. Our calculations allow a fully controlled, ab initio determination of the pion decay constant with a total 1% error, which is in excellent agreement with experiment.
Nuclear chiral dynamics and thermodynamics
Holt, Jeremy W.; Kaiser, Norbert; Weise, Wolfram
2013-11-01
This presentation reviews an approach to nuclear many-body systems based on the spontaneously broken chiral symmetry of low-energy QCD. In the low-energy limit, for energies and momenta small compared to a characteristic symmetry breaking scale of order 1 GeV, QCD is realized as an effective field theory of Goldstone bosons (pions) coupled to heavy fermionic sources (nucleons). Nuclear forces at long and intermediate distance scales result from a systematic hierarchy of one- and two-pion exchange processes in combination with Pauli blocking effects in the nuclear medium. Short distance dynamics, not resolved at the wavelengths corresponding to typical nuclear Fermi momenta, are introduced as contact interactions between nucleons. Apart from a set of low-energy constants associated with these contact terms, the parameters of this theory are entirely determined by pion properties and low-energy pion-nucleon scattering observables. This framework (in-medium chiral perturbation theory) can provide a realistic description of both isospin-symmetric nuclear matter and neutron matter, with emphasis on the isospin-dependence determined by the underlying chiral NN interaction. The importance of three-body forces is emphasized, and the role of explicit Δ(1232)-isobar degrees of freedom is investigated in detail. Nuclear chiral thermodynamics is developed and a calculation of the nuclear phase diagram is performed. This includes a successful description of the first-order phase transition from a nuclear Fermi liquid to an interacting Fermi gas and the coexistence of these phases below a critical temperature Tc. Density functional methods for finite nuclei based on this approach are also discussed. Effective interactions, their density dependence and connections to Landau Fermi liquid theory are outlined. Finally, the density and temperature dependences of the chiral (quark) condensate are investigated.
Integrable anyon chains: From fusion rules to face models to effective field theories
International Nuclear Information System (INIS)
Finch, Peter E.; Flohr, Michael; Frahm, Holger
2014-01-01
Starting from the fusion rules for the algebra SO(5) 2 we construct one-dimensional lattice models of interacting anyons with commuting transfer matrices of ‘interactions round the face’ (IRF) type. The conserved topological charges of the anyon chain are recovered from the transfer matrices in the limit of large spectral parameter. The properties of the models in the thermodynamic limit and the low energy excitations are studied using Bethe ansatz methods. Two of the anyon models are critical at zero temperature. From the analysis of the finite size spectrum we find that they are effectively described by rational conformal field theories invariant under extensions of the Virasoro algebra, namely WB 2 and WD 5 , respectively. The latter contains primaries with half and quarter spin. The modular partition function and fusion rules are derived and found to be consistent with the results for the lattice model
Multi-hadron-state contamination in nucleon observables from chiral perturbation theory
Bär, Oliver
2018-03-01
Multi-particle states with additional pions are expected to be a non-negligible source of the excited-state contamination in lattice simulations at the physical point. It is shown that baryon chiral perturbation theory (ChPT) can be employed to calculate the contamination due to two-particle nucleon-pion states in various nucleon observables. Results to leading order are presented for the nucleon axial, tensor and scalar charge and three Mellin moments of parton distribution functions: the average quark momentum fraction, the helicity and the transversity moment. Taking into account experimental and phenomenological results for the charges and moments the impact of the nucleon-pionstates on lattice estimates for these observables can be estimated. The nucleon-pion-state contribution leads to an overestimation of all charges and moments obtained with the plateau method. The overestimation is at the 5-10% level for source-sink separations of about 2 fm. Existing lattice data is not in conflict with the ChPT predictions, but the comparison suggests that significantly larger source-sink separations are needed to compute the charges and moments with few-percent precision. Talk given at the 35th International Symposium on Lattice Field Theory, 18 - 24 June 2017, Granada, Spain.
The nucleon as soliton in an effective chiral theory with polarized Dirac sea
International Nuclear Information System (INIS)
Meissner, T.
1991-07-01
We consider the Nambu-Jona-Lasinio model for SU(2) flavor with N F = 3 color degrees of freedom and a current mass m o =m u =m d , which interact via scalar-isoscalar and pseudoscalar-isovectorial 4-point coupling of the strength G. We show that it is for the soft-poin limit essentially equivalent to treat the 4-quark theory in the HFA+BSE and the bozonized theory with classical meson fields, if the collective field π with the physical pion. By the requirement that in the vacuum the experimental values for the pion mass m π =139 MeV and the weak pion decay constant f π =93 MeV are reproduced finally only one free parameter remains, which is in our case the constituent quark mass M. All other parameters and vacuum quantities can be calculated as function of M. We do this for the UV cut-off parameter Λ, the 4-quark coupling strength G, the quark current mass m O as well as the vacuum condensate (anti qq)v. Thereby especially the influence of the regularization scheme on m O and (anti q)v is studied. For the construction of states with good spin and isospin quantum numbers we apply the semiclassical cranking procedure. Finally we compare the NJL with the chiral sigma model of Gell-Mann and Levi, which is connected with the NJL by the gradient respectively heat-kernel expansion. (orig./HSI) [de
Leading order relativistic chiral nucleon-nucleon interaction
Ren, Xiu-Lei; Li, Kai-Wen; Geng, Li-Sheng; Long, Bingwei; Ring, Peter; Meng, Jie
2018-01-01
Motivated by the successes of relativistic theories in studies of atomic/molecular and nuclear systems and the need for a relativistic chiral force in relativistic nuclear structure studies, we explore a new relativistic scheme to construct the nucleon-nucleon interaction in the framework of covariant chiral effective field theory. The chiral interaction is formulated up to leading order with covariant power counting and a Lorentz invariant chiral Lagrangian. We find that the relativistic scheme induces all six spin operators needed to describe the nuclear force. A detailed investigation of the partial wave potentials shows a better description of the {}1S0 and {}3P0 phase shifts than the leading order Weinberg approach, and similar to that of the next-to-leading order Weinberg approach. For the other partial waves with angular momenta J≥slant 1, the relativistic results are almost the same as their leading order non-relativistic counterparts. )
Higgs decays to Z Z and Z γ in the standard model effective field theory: An NLO analysis
Dawson, S.; Giardino, P. P.
2018-05-01
We calculate the complete one-loop electroweak corrections to the inclusive H →Z Z and H →Z γ decays in the dimension-6 extension of the Standard Model Effective Field Theory (SMEFT). The corrections to H →Z Z are computed for on-shell Z bosons and are a precursor to the physical H →Z f f ¯ calculation. We present compact numerical formulas for our results and demonstrate that the logarithmic contributions that result from the renormalization group evolution of the SMEFT coefficients are larger than the finite next-to-leading-order contributions to the decay widths. As a byproduct of our calculation, we obtain the first complete result for the finite corrections to Gμ in the SMEFT.
Energy Technology Data Exchange (ETDEWEB)
Bahl, Henning; Hollik, Wolfgang [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Munich (Germany)
2016-09-15
In the Minimal Supersymmetric Standard Model heavy superparticles introduce large logarithms in the calculation of the lightest CP-even Higgs-boson mass. These logarithmic contributions can be resummed using effective field theory techniques. For light superparticles, however, fixed-order calculations are expected to be more accurate. To gain a precise prediction also for intermediate mass scales, the two approaches have to be combined. Here, we report on an improvement of this method in various steps: the inclusion of electroweak contributions, of separate electroweakino and gluino thresholds, as well as resummation at the NNLL level. These improvements can lead to significant numerical effects. In most cases, the lightest CP-even Higgs-boson mass is shifted downwards by about 1 GeV. This is mainly caused by higher-order corrections to the MS top-quark mass. We also describe the implementation of the new contributions in the code FeynHiggs. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Behbahani, Siavosh R.; /SLAC /Stanford U., Phys. Dept. /Boston U.; Dymarsky, Anatoly; /Princeton, Inst. Advanced Study; Mirbabayi, Mehrdad; /New York U., CCPP /New York U.; Senatore, Leonardo; /Stanford U., Phys. Dept. /KIPAC, Menlo Park
2012-06-06
We apply the Effective Field Theory of Inflation to study the case where the continuous shift symmetry of the Goldstone boson {pi} is softly broken to a discrete subgroup. This case includes and generalizes recently proposed String Theory inspired models of Inflation based on Axion Monodromy. The models we study have the property that the 2-point function oscillates as a function of the wavenumber, leading to oscillations in the CMB power spectrum. The non-linear realization of time diffeomorphisms induces some self-interactions for the Goldstone boson that lead to a peculiar non-Gaussianity whose shape oscillates as a function of the wavenumber. We find that in the regime of validity of the effective theory, the oscillatory signal contained in the n-point correlation functions, with n > 2, is smaller than the one contained in the 2-point function, implying that the signature of oscillations, if ever detected, will be easier to find first in the 2-point function, and only then in the higher order correlation functions. Still the signal contained in higher-order correlation functions, that we study here in generality, could be detected at a subleading level, providing a very compelling consistency check for an approximate discrete shift symmetry being realized during inflation.
Energy Technology Data Exchange (ETDEWEB)
Walker-Loud, Andre [College of William and Mary, Williamsburg, VA (United States)
2016-10-14
The research supported by this grant is aimed at probing the limits of the Standard Model through precision low-energy nuclear physics. The work of the PI (AWL) and additional personnel is to provide theory input needed for a number of potentially high-impact experiments, notably, hadronic parity violation, Dark Matter direct detection and searches for permanent electric dipole moments (EDMs) in nucleons and nuclei. In all these examples, a quantitative understanding of low-energy nuclear physics from the fundamental theory of strong interactions, Quantum Chromo-Dynamics (QCD), is necessary to interpret the experimental results. The main theoretical tools used and developed in this work are the numerical solution to QCD known as lattice QCD (LQCD) and Effective Field Theory (EFT). This grant is supporting a new research program for the PI, and as such, needed to be developed from the ground up. Therefore, the first fiscal year of this grant, 08/01/2014-07/31/2015, has been spent predominantly establishing this new research effort. Very good progress has been made, although, at this time, there are not many publications to show for the effort. After one year, the PI accepted a job at Lawrence Berkeley National Laboratory, so this final report covers just a single year of five years of the grant.
Energy Technology Data Exchange (ETDEWEB)
Bernard, V. [Universite Louis Pasteur, Laboratoire de Physique Theorique, Strasbourg Cedex 2 (France); Kubis, B. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Bonn (Germany); Meissner, U.G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Bonn (Germany); Forschungszentrum Juelich, Institut fuer Kernphysik (Theorie), Juelich (Germany)
2005-09-01
We analyze the Fubini-Furlan-Rosetti sum rule in the framework of covariant baryon chiral perturbation theory to leading one-loop accuracy and including next-to-leading-order polynomial contributions. We discuss the relation between the subtraction constants in the invariant amplitudes and certain low-energy constants employed in earlier chiral perturbation theory studies of threshold neutral pion photoproduction off nucleons. In particular, we consider the corrections to the sum rule due to the finite pion mass and show that below the threshold they agree well with determinations based on fixed-t dispersion relations. We also discuss the energy dependence of the electric dipole amplitude E{sub 0+}. (orig.)
International Nuclear Information System (INIS)
Thierry-Mieg, Jean
2006-01-01
In Yang-Mills theory, the charges of the left and right massless Fermions are independent of each other. We propose a new paradigm where we remove this freedom and densify the algebraic structure of Yang-Mills theory by integrating the scalar Higgs field into a new gauge-chiral 1-form which connects Fermions of opposite chiralities. Using the Bianchi identity, we prove that the corresponding covariant differential is associative if and only if we gauge a Lie-Kac super-algebra. In this model, spontaneous symmetry breakdown naturally occurs along an odd generator of the super-algebra and induces a representation of the Connes-Lott non commutative differential geometry of the 2-point finite space
International Nuclear Information System (INIS)
Berube, D.; Kroeger, H.; Lafrance, R.; Marleau, L.
1991-01-01
We discuss properties of a noncompact formulation of gauge theories with fermions on a momentum (k) lattice. (a) This formulation is suitable to build in Fourier acceleration in a direct way. (b) The numerical effort to compute the action (by fast Fourier transform) goes essentially like logV with the lattice volume V. (c) For the Yang-Mills theory we find that the action conserves gauge symmetry and chiral symmetry in a weak sense: On a finite lattice the action is invariant under infinitesimal transformations with compact support. Under finite transformations these symmetries are approximately conserved and they are restored on an infinite lattice and in the continuum limit. Moreover, these symmetries also hold on a finite lattice under finite transformations, if the classical fields, instead of being c-number valued, take values from a finite Galois field. (d) There is no fermion doubling. (e) For the φ 4 model we investigate the transition towards the continuum limit in lattice perturbation theory up to second order. We compute the two- and four-point functions and find local and Lorentz-invariant results. (f) In QED we compute a one-loop vacuum polarization and find in the continuum limit the standard result. (g) As a numerical application, we compute the propagator left-angle φ(k)φ(k')right-angle in the φ 4 model, investigate Euclidean invariance, and extract m R as well as Z R . Moreover we compute left-angle F μν (k)F μν (k')right-angle in the SU(2) model
Chiral symmetry and strangeness at SIS energies
International Nuclear Information System (INIS)
Lutz, M.F.M.
2003-11-01
In this talk we review the consequences of the chiral SU(3) symmetry for strangeness propagation in nuclear matter. Objects of crucial importance are the meson-baryon scattering amplitudes obtained within the chiral coupled-channel effective field theory. Results for antikaon and hyperon-resonance spectral functions in cold nuclear matter are presented and discussed. The importance of the Σ(1385) resonance for the subthreshold antikaon production in heavy-ion reaction at SIS is pointed out. The in-medium properties of the latter together with an antikaon spectral function based on chiral SU(3) dynamics suggest a significant enhancement of the π Λ → anti Κ N reaction in nuclear matter. (orig.)
Complete conformal field theory solution of a chiral six-point correlation function
International Nuclear Information System (INIS)
Simmons, Jacob J H; Kleban, Peter
2011-01-01
Using conformal field theory, we perform a complete analysis of the chiral six-point correlation function C(z)= 1,2 φ 1,2 Φ 1/2,0 (z, z-bar )φ 1,2 φ 1,2 >, with the four φ 1,2 operators at the corners of an arbitrary rectangle, and the point z = x + iy in the interior. We calculate this for arbitrary central charge (equivalently, SLE parameter κ > 0). C is of physical interest because for percolation (κ = 6) and many other two-dimensional critical points, it specifies the density at z of critical clusters conditioned to touch either or both vertical ends of the rectangle, with these ends 'wired', i.e. constrained to be in a single cluster, and the horizontal ends free. The correlation function may be written as the product of an algebraic prefactor f and a conformal block G, where f = f(x, y, m), with m a cross-ratio specified by the corners (m determines the aspect ratio of the rectangle). By appropriate choice of f and using coordinates that respect the symmetry of the problem, the conformal block G is found to be independent of either y or x, and given by an Appell function.
A Study of ρ-ω Mixing in Resonance Chiral Theory
Chen, Yun-Hua; Yao, De-Liang; Zheng, Han-Qing
2018-01-01
The strong and electromagnetic corrections to ρ-ω mixing are calculated using an SU(2) version of resonance chiral theory up to next-to-leading orders in 1/{N}C expansion, respectively. Up to our accuracy, the effect of the momentum dependence of ρ-ω mixing is incorporated due to the inclusion of loop contributions. We analyze the impact of ρ-ω mixing on the pion vector form factor by performing numerical fit to the data extracted from {e}+{e}-\\to {π }+{π }- and τ \\to {ν }τ 2π , while the decay width of ω \\to {π }+{π }- is taken into account as a constraint. It is found that the momentum dependence is significant in a good description of the experimental data. In addition, based on the fitted values of the involved parameters, we analyze the decay width of ω \\to {π }+{π }-, which turns out to be highly dominated by the ρ-ω mixing effect. Supported in part by the Fundamental Research Funds for the Central Universities under Grant No. 06500077, the Spanish Ministerio de Economía y Competitividad and the European Regional Development Fund, under Grant Nos. FIS2014-51948-C2-1-P, FIS2014-51948-C2-2-P, SEV-2014-0398, and Generalitat Valenciana under Grant No. PROMETEOII/2014/0068
Field transformations and the classical equation of motion in chiral perturbation theory
International Nuclear Information System (INIS)
Scherer, S.; Fearing, H.W.
1995-01-01
The construction of effective Lagrangians commonly involves the application of the ''classical equation of motion'' to eliminate redundant structures and thus generate the minimal number of independent terms. We investigate this procedure in the framework of chiral perturbation theory with particular emphasis on the new features which appear at O(p 6 ). The use of the ''classical equation of motion'' is interpreted in terms of field transformations. Such an interpretation is crucial if one wants to bring a given Lagrangian into a canonical form with a minimal number of terms. We emphasize that the application of field transformations leads to a modification of the coefficients of higher-order terms as well as eliminating structures, or what is equivalent, expressing certain structures in terms of already known different structures. This will become relevant once one considers the problem of expressing in canonical form a model effective interaction containing terms beyond next-to-leading order, i.e., beyond O(p 4 ). In such circumstances the naive application of the clasical equation of motion to simply drop terms, as is commonly done at lowest order, leads to subtle errors, which we discuss
Levi, Michele; Steinhoff, Jan
2017-12-01
We present a novel public package ‘EFTofPNG’ for high precision computation in the effective field theory of post-Newtonian (PN) gravity, including spins. We created this package in view of the timely need to publicly share automated computation tools, which integrate the various types of physics manifested in the expected increasing influx of gravitational wave (GW) data. Hence, we created a free and open source package, which is self-contained, modular, all-inclusive, and accessible to the classical gravity community. The ‘EFTofPNG’ Mathematica package also uses the power of the ‘xTensor’ package, suited for complicated tensor computation, where our coding also strategically approaches the generic generation of Feynman contractions, which is universal to all perturbation theories in physics, by efficiently treating n-point functions as tensors of rank n. The package currently contains four independent units, which serve as subsidiaries to the main one. Its final unit serves as a pipeline chain for the obtainment of the final GW templates, and provides the full computation of derivatives and physical observables of interest. The upcoming ‘EFTofPNG’ package version 1.0 should cover the point mass sector, and all the spin sectors, up to the fourth PN order, and the two-loop level. We expect and strongly encourage public development of the package to improve its efficiency, and to extend it to further PN sectors, and observables useful for the waveform modelling.
Chiral correlators in Landau-Ginsburg theories and N=2 superconformal models
International Nuclear Information System (INIS)
Howe, P.S.; West, P.C.
1989-01-01
Chiral correlation functions are computed in N=2 Landau-Ginsburg models using the ε-expansion and the superconformal Ward identities for the Landau-Ginsburg effective action. They are also computed directly using superconformal model techniques. The same results are obtained yielding further confirmation of the identification of superconformal minimal models with Landau-Ginsburg models evaluated at their fixed points. The formulae for the chiral commutators that we compute are extremely simple when expressed in terms of effective actions. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Bijnens, Johan; Rössler, Thomas [Department of Astronomy and Theoretical Physics, Lund University,Sölvegatan 14A, SE 223-62 Lund (Sweden)
2015-11-16
We present a calculation of the finite volume corrections to meson masses and decay constants in three flavour Partially Quenched Chiral Perturbation Theory (PQChPT) through two-loop order in the chiral expansion for the flavour-charged (or off-diagonal) pseudoscalar mesons. The analytical results are obtained for three sea quark flavours with one, two or three different masses. We reproduce the known infinite volume results and the finite volume results in the unquenched case. The calculation has been performed using the supersymmetric formulation of PQChPT as well as with a quark flow technique. Partial analytical results can be found in the appendices. Some examples of cases relevant to lattice QCD are studied numerically. Numerical programs for all results are available as part of the CHIRON package.
Torons, chiral symmetry breaking and U(1) problem in σ-model and gauge theories. Part 2
International Nuclear Information System (INIS)
Zhitnitskij, A.R.
1989-01-01
The main point of this work is the physical consenquences of the existence of fractional charge in the σ-models and espesially in the physically interesting theory QCD. It is shown that the corresponding fluctuations ensure spontaneous breaking of the chiral symmetry and give a nonzero contribution to the chiral condensate. Toron solution is determined on the manifold with boundary. In this case many questions arise such as: global boundary conditions, the stability of the solution, self-adjointness of Dirac operator, single-valuedness of the physical values and so on. These questions are interconnected and turn out to be self cobsistent only for the special choice of the topological number (Q=1/2 for SU(2)). It is shown that in the Dirac's spectrum of the quarks the gap between zero and the continuum is absent. 50 refs.; 10 figs
International Nuclear Information System (INIS)
Bijnens, Johan; Rössler, Thomas
2015-01-01
We present a calculation of the finite volume corrections to meson masses and decay constants in three flavour Partially Quenched Chiral Perturbation Theory (PQChPT) through two-loop order in the chiral expansion for the flavour-charged (or off-diagonal) pseudoscalar mesons. The analytical results are obtained for three sea quark flavours with one, two or three different masses. We reproduce the known infinite volume results and the finite volume results in the unquenched case. The calculation has been performed using the supersymmetric formulation of PQChPT as well as with a quark flow technique. Partial analytical results can be found in the appendices. Some examples of cases relevant to lattice QCD are studied numerically. Numerical programs for all results are available as part of the CHIRON package.
Algebraic study of chiral anomalies
Indian Academy of Sciences (India)
Chiral anomalies; gauge theories; bundles; connections; quantum ﬁeld ... The algebraic structure of chiral anomalies is made globally valid on non-trivial bundles by the introduction of a ﬁxed background connection. ... Current Issue : Vol.
Ciattoni, Alessandro; Rizza, Carlo
2015-05-01
We develop, from first principles, a general and compact formalism for predicting the electromagnetic response of a metamaterial with nonmagnetic inclusions in the long-wavelength limit, including spatial dispersion up to the second order. Specifically, by resorting to a suitable multiscale technique, we show that the effective medium permittivity tensor and the first- and second-order tensors describing spatial dispersion can be evaluated by averaging suitable spatially rapidly varying fields, each satisfying electrostatic-like equations within the metamaterial unit cell. For metamaterials with negligible second-order spatial dispersion, we exploit the equivalence of first-order spatial dispersion and reciprocal bianisotropic electromagnetic response to deduce a simple expression for the metamaterial chirality tensor. Such an expression allows us to systematically analyze the effect of the composite spatial symmetry properties on electromagnetic chirality. We find that even if a metamaterial is geometrically achiral, i.e., it is indistinguishable from its mirror image, it shows pseudo-chiral-omega electromagnetic chirality if the rotation needed to restore the dielectric profile after the reflection is either a 0∘ or 90∘ rotation around an axis orthogonal to the reflection plane. These two symmetric situations encompass two-dimensional and one-dimensional metamaterials with chiral response. As an example admitting full analytical description, we discuss one-dimensional metamaterials whose single chirality parameter is shown to be directly related to the metamaterial dielectric profile by quadratures.
B→D*lν and B→Dlν form factors in staggered chiral perturbation theory
International Nuclear Information System (INIS)
Laiho, Jack; Water, Ruth S. van de
2006-01-01
We calculate the B→D and B→D* form factors at zero recoil in staggered chiral perturbation theory. We consider heavy-light mesons in which only the light (u, d, or s) quark is staggered; current lattice simulations generally use a highly improved action such as the Fermilab or nonrelativistic QCD action for the heavy (b or c) quark. We work to lowest nontrivial order in the heavy-quark expansion and to one-loop order in the chiral expansion. We present results for a partially quenched theory with three sea quarks in which there are no mass degeneracies (the ''1+1+1'' theory) and for a partially quenched theory in which the u and d sea quark masses are equal (the ''2+1'' theory). We also present results for full (2+1) QCD, along with a numerical estimate of the size of staggered discretization errors. Finally, we calculate the finite volume corrections to the form factors and estimate their numerical size in current lattice simulations
Neutron-proton scattering at next-to-next-to-leading order in Nuclear Lattice Effective Field Theory
Energy Technology Data Exchange (ETDEWEB)
Alarcon, Jose Manuel [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Thomas Jefferson National Accelerator Facility, Theory Center, Newport News, VA (United States); Du, Dechuan; Laehde, Timo A.; Li, Ning; Lu, Bing-Nan; Luu, Thomas [Institute for Advanced Simulation, Institut fuer Kernphysik, and Juelich Center for Hadron Physics, Forschungszentrum Juelich, Juelich (Germany); Klein, Nico [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Lee, Dean [North Carolina State University, Department of Physics, Raleigh, NC (United States); Meissner, Ulf G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Institute for Advanced Simulation, Institut fuer Kernphysik, and Juelich Center for Hadron Physics, Forschungszentrum Juelich, Juelich (Germany); Forschungszentrum Juelich, JARA - High Performance Computing, Juelich (Germany)
2017-05-15
We present a systematic study of neutron-proton scattering in Nuclear Lattice Effective Field Theory (NLEFT), in terms of the computationally efficient radial Hamiltonian method. Our leading-order (LO) interaction consists of smeared, local contact terms and static one-pion exchange. We show results for a fully non-perturbative analysis up to next-to-next-to-leading order (NNLO), followed by a perturbative treatment of contributions beyond LO. The latter analysis anticipates practical Monte Carlo simulations of heavier nuclei. We explore how our results depend on the lattice spacing a, and estimate sources of uncertainty in the determination of the low-energy constants of the next-to-leading-order (NLO) two-nucleon force. We give results for lattice spacings ranging from a = 1.97 fm down to a = 0.98 fm, and discuss the effects of lattice artifacts on the scattering observables. At a = 0.98 fm, lattice artifacts appear small, and our NNLO results agree well with the Nijmegen partial-wave analysis for S-wave and P-wave channels. We expect the peripheral partial waves to be equally well described once the lattice momenta in the pion-nucleon coupling are taken to coincide with the continuum dispersion relation, and higher-order (N3LO) contributions are included. We stress that for center-of-mass momenta below 100 MeV, the physics of the two-nucleon system is independent of the lattice spacing. (orig.)
Lombardi, G.; Van Alphen, W.; Klimin, S. N.; Tempere, J.
2017-09-01
In the present article the snake instability mechanism for dark solitons in superfluid Fermi gases is studied in the context of a recently developed effective field theory [S. N. Klimin et al., Eur. Phys. J. B 88, 122 (2015), 10.1140/epjb/e2015-60213-4]. This theoretical treatment has proven to be suitable to study stable dark solitons in quasi-one-dimensional setups across the BEC-BCS crossover. In this paper the nodal plane of the stable soliton solution is perturbed by adding a transverse modulation. The numerical solution of the system of coupled nonlinear differential equations describing the amplitude of the perturbation leads to an estimate of the growth rate and characteristic length scale of the instability, which are calculated for a wide range of interaction regimes and compared to other theoretical predictions. The behavior of the maximum transverse size that the atomic cloud can have in order to preserve the stability is described across the BEC-BCS crossover. The analysis of the effects of spin imbalance on this critical length reveals a stabilization of the soliton with increasing imbalance and therefore provides the experimental community with a method to achieve the realization of stable solitons in real three-dimensional configurations, without reducing the system dimensionality.
International Nuclear Information System (INIS)
Kantar, Ersin; Keskin, Mustafa
2014-01-01
We propose a ternary Ising spins (1/2, 1, 3/2) model to investigate the thermal and magnetic properties of magnetic nanoparticles with core–shell structure within the framework of the effective-field theory with correlations. The center site of the core is occupied by σ=±1/2 spin, while those surrounding the center site are occupied by S=±1, 0 spins and the shell sites are occupied by m=±1/2,±3/2 spins. Thermal behaviors of the core and shell magnetizations, susceptibilities and internal energies as well as total magnetization are examined. In order to confirm the stability of the solutions we also investigate the free energy of the system. According to the values of Hamiltonian parameters, the system undergoes first- and second-order phase transitions. Phase diagrams are calculated and discussed in detail. We find that the system exhibits a tricritical point, reentrant and five different type (Q, P, R, S and W) of compensation behaviors that strongly depend on interaction parameters. The results are in good agreement with some experimental and theoretical results. - Highlights: • Thermal and magnetic properties of ternary Ising nanoparticles are studied. • Phase diagrams within the EFT with correlations are calculated and discussed. • The effects of the exchange interactions and crystal field have been studied. • Reentrant phenomena and compensation behaviors have been found
Energy Technology Data Exchange (ETDEWEB)
Kantar, Ersin [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Institute of Science, Erciyes University, 38039 Kayseri (Turkey); Keskin, Mustafa, E-mail: keskin@erciyes.edu.tr [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)
2014-01-15
We propose a ternary Ising spins (1/2, 1, 3/2) model to investigate the thermal and magnetic properties of magnetic nanoparticles with core–shell structure within the framework of the effective-field theory with correlations. The center site of the core is occupied by σ=±1/2 spin, while those surrounding the center site are occupied by S=±1, 0 spins and the shell sites are occupied by m=±1/2,±3/2 spins. Thermal behaviors of the core and shell magnetizations, susceptibilities and internal energies as well as total magnetization are examined. In order to confirm the stability of the solutions we also investigate the free energy of the system. According to the values of Hamiltonian parameters, the system undergoes first- and second-order phase transitions. Phase diagrams are calculated and discussed in detail. We find that the system exhibits a tricritical point, reentrant and five different type (Q, P, R, S and W) of compensation behaviors that strongly depend on interaction parameters. The results are in good agreement with some experimental and theoretical results. - Highlights: • Thermal and magnetic properties of ternary Ising nanoparticles are studied. • Phase diagrams within the EFT with correlations are calculated and discussed. • The effects of the exchange interactions and crystal field have been studied. • Reentrant phenomena and compensation behaviors have been found.
International Nuclear Information System (INIS)
Choudhury, Sayantan
2015-01-01
In this paper my prime objective is to explain the generation of large tensor-to-scalar ratio from the single field sub-Planckian inflationary paradigm within Randall–Sundrum (RS) single braneworld scenario in a model independent fashion. By explicit computation I have shown that the effective field theory prescription of brane inflation within RS single brane setup is consistent with sub-Planckian excursion of the inflaton field, which will further generate large value of tensor-to-scalar ratio, provided the energy density for inflaton degrees of freedom is high enough compared to the brane tension in high energy regime. Finally, I have mentioned the stringent theoretical constraint on positive brane tension, cut-off of the quantum gravity scale and bulk cosmological constant to get sub-Planckian field excursion along with large tensor-to-scalar ratio as recently observed by BICEP2 or at least generates the tensor-to-scalar ratio consistent with the upper bound of Planck (2013 and 2015) data and Planck+BICEP2+Keck Array joint constraint
Energy Technology Data Exchange (ETDEWEB)
Becher,
2002-08-08
After contrasting the low energy effective theory for the baryon sector with one for the Goldstone sector, I use the example of pion nucleon scattering to discuss some of the progress and open issues in baryon chiral perturbation theory.
Sawa, Y.; Yokoyama, T.; Tanaka, Y.; Golubov, Alexandre Avraamovitch
2007-01-01
We study the Josephson effect in chiral p-wave superconductor/diffusive normal metal (DN)/chiral p-wave superconductor (CP/DN/CP) junctions using quasiclassical Green's function formalism with proper boundary conditions. The px+ipy-wave symmetry of superconducting order parameter is chosen which is
Pion–nucleon scattering: from chiral perturbation theory to Roy–Steiner equations
International Nuclear Information System (INIS)
Kubis, Bastian; Hoferichter, Martin; Elvira, Jacobo Ruiz de; Meißner, Ulf-G.
2016-01-01
Ever since Weinberg’s seminal predictions of the pion–nucleon scattering amplitudes at threshold, this process has been of central interest for the study of chiral dynamics involving nucleons. The scattering lengths or the pion–nucleon σ-term are fundamental quantities characterizing the explicit breaking of chiral symmetry by means of the light quark masses. On the other hand, pion–nucleon dynamics also strongly affects the long-range part of nucleon–nucleon potentials, and hence has a far-reaching impact on nuclear physics. We discuss the fruitful combination of dispersion-theoretical methods, in the form of Roy–Steiner equations, with chiral dynamics to determine pion–nucleon scattering amplitudes at low energies with high precision.
Pion-nucleon scattering: from chiral perturbation theory to Roy-Steiner equations
Kubis, Bastian; Hoferichter, Martin; de Elvira, Jacobo Ruiz; Meißner, Ulf-G.
2016-11-01
Ever since Weinberg's seminal predictions of the pion-nucleon scattering amplitudes at threshold, this process has been of central interest for the study of chiral dynamics involving nucleons. The scattering lengths or the pion-nucleon σ-term are fundamental quantities characterizing the explicit breaking of chiral symmetry by means of the light quark masses. On the other hand, pion-nucleon dynamics also strongly affects the long-range part of nucleon-nucleon potentials, and hence has a far-reaching impact on nuclear physics. We discuss the fruitful combination of dispersion-theoretical methods, in the form of Roy-Steiner equations, with chiral dynamics to determine pion-nucleon scattering amplitudes at low energies with high precision.*
Assuming Regge trajectories in holographic QCD: from OPE to Chiral Perturbation Theory
Cappiello, Luigi; Greynat, David
2015-01-01
The Soft Wall model in holographic QCD has Regge trajectories but wrong operator product expansion (OPE) for the two-point vectorial QCD Green function. We correct analytically this problem and describe the axial sector and chiral symmetry breaking. The low energy chiral parameters, $F_{\\pi}$ and $L_{10}$ , are well described analytically by the model in terms of Regge spacing and QCD condensates. The model nicely supports and extends previous theoretical analyses advocating Digamma function to study QCD two-point functions in different momentum regions.
Torons, chiral symmetry breaking and U(1) problem in σ-model and in gauge theories. Part 1
International Nuclear Information System (INIS)
Zhitnitskij, A.R.
1989-01-01
A novel class of self-dual solutions in σ-models and in SU(2) gauge theories is considered. The solution is defined on manifold with boundary, it has topological charge Q=1/2. The contribution of the corresponding fluctuations and toron configurations to chiral condensate is calculated. This contribution has finite nonzero value. The APS (Atiyah, Patodi, Singer) theorem for a manifold with a boundary is discussed for the O(3) σ model. The necessity of imposing non-local boundary conditions for the Dirac operator is explained. 30 refs.; 4 figs
International Nuclear Information System (INIS)
Zhang Honghao; Yan Wenbin; Li Xuesong
2008-01-01
By using combinatorics, we give a new proof for the recurrence relations of the characteristic polynomial coefficients, and we further obtain an explicit expression for the generic term of the coefficient sequence, which yields the trace formulae of the Cayley-Hamilton's theorem with all coefficients explicitly given. This implies a byproduct, a complete expression for the determinant of any finite-dimensional matrix in terms of the traces of its successive powers. And we discuss some of their applications to chiral perturbation theory and general relativity
T-odd correlations in radiative K{sup +} {sub l3} decays and chiral perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Mueller, E.H.; Kubis, B. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Meissner, U.G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Forschungszentrum Juelich, Institut fuer Kernphysik (Theorie), Juelich (Germany)
2006-11-15
The charged kaon decay channel K{sup +} {sub l3{gamma}} allows for studies of direct CP violation, possibly due to non-standard mechanisms, with the help of T-odd correlation variables. In order to be able to extract a CP-violating signal from experiment, it is necessary to understand all possible standard model phases that also produce T-odd asymmetries. We complement earlier studies by considering strong interaction phases in hadronic structure functions that appear at higher orders in chiral perturbation theory, and we compare our findings to other potential sources of asymmetries. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Levi, Michele [Université Pierre et Marie Curie, CNRS-UMR 7095, Institut d' Astrophysique de Paris, 98 bis Boulevard Arago, 75014 Paris (France); Steinhoff, Jan, E-mail: michele.levi@upmc.fr, E-mail: jan.steinhoff@aei.mpg.de [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute), Am Mühlenberg 1, 14476 Potsdam-Golm (Germany)
2016-01-01
We implement the effective field theory for gravitating spinning objects in the post-Newtonian scheme at the next-to-next-to-leading order level to derive the gravitational spin-orbit interaction potential at the third and a half post-Newtonian order for rapidly rotating compact objects. From the next-to-next-to-leading order interaction potential, which we obtain here in a Lagrangian form for the first time, we derive straightforwardly the corresponding Hamiltonian. The spin-orbit sector constitutes the most elaborate spin dependent sector at each order, and accordingly we encounter a proliferation of the relevant Feynman diagrams, and a significant increase of the computational complexity. We present in detail the evaluation of the interaction potential, going over all contributing Feynman diagrams. The computation is carried out in terms of the ''nonrelativistic gravitational'' fields, which are advantageous also in spin dependent sectors, together with the various gauge choices included in the effective field theory for gravitating spinning objects, which also optimize the calculation. In addition, we automatize the effective field theory computations, and carry out the automated computations in parallel. Such automated effective field theory computations would be most useful to obtain higher order post-Newtonian corrections. We compare our Hamiltonian to the ADM Hamiltonian, and arrive at a complete agreement between the ADM and effective field theory results. Finally, we provide Hamiltonians in the center of mass frame, and complete gauge invariant relations among the binding energy, angular momentum, and orbital frequency of an inspiralling binary with generic compact spinning components to third and a half post-Newtonian order. The derivation presented here is essential to obtain further higher order post-Newtonian corrections, and to reach the accuracy level required for the successful detection of gravitational radiation.
Chiral and continuum extrapolation of partially-quenched hadron masses
International Nuclear Information System (INIS)
Chris Allton; Wes Armour; Derek Leinweber; Anthony Thomas; Ross Young
2005-01-01
Using the finite-range regularization (FRR) of chiral effective field theory, the chiral extrapolation formula for the vector meson mass is derived for the case of partially-quenched QCD. We re-analyze the dynamical fermion QCD data for the vector meson mass from the CP-PACS collaboration. A global fit, including finite lattice spacing effects, of all 16 of their ensembles is performed. We study the FRR method together with a naive polynomial approach and find excellent agreement (∼1%) with the experimental value of M ρ from the former approach. These results are extended to the case of the nucleon mass
Chiral and continuum extrapolation of partially-quenched hadron masses
Energy Technology Data Exchange (ETDEWEB)
Chris Allton; Wes Armour; Derek Leinweber; Anthony Thomas; Ross Young
2005-09-29
Using the finite-range regularization (FRR) of chiral effective field theory, the chiral extrapolation formula for the vector meson mass is derived for the case of partially-quenched QCD. We re-analyze the dynamical fermion QCD data for the vector meson mass from the CP-PACS collaboration. A global fit, including finite lattice spacing effects, of all 16 of their ensembles is performed. We study the FRR method together with a naive polynomial approach and find excellent agreement ({approx}1%) with the experimental value of M{sub {rho}} from the former approach. These results are extended to the case of the nucleon mass.
Chiral dynamics and peripheral transverse densities
Energy Technology Data Exchange (ETDEWEB)
Granados, Carlos G. [Uppsala University (Sweden); Weiss, Christian [JLAB, Newport News, VA (United States)
2014-01-01
In the partonic (or light-front) description of relativistic systems the electromagnetic form factors are expressed in terms of frame-independent charge and magnetization densities in transverse space. This formulation allows one to identify the chiral components of nucleon structure as the peripheral densities at transverse distances b = O(M{sub {pi}}{sup -1}) and compute them in a parametrically controlled manner. A dispersion relation connects the large-distance behavior of the transverse charge and magnetization densities to the spectral functions of the Dirac and Pauli form factors near the two--pion threshold at timelike t = 4 M{ sub {pi}}{sup 2}, which can be computed in relativistic chiral effective field theory. Using the leading-order approximation we (a) derive the asymptotic behavior (Yukawa tail) of the isovector transverse densities in the "chiral" region b = O(M{sub {pi}}{sup -1}) and the "molecular" region b = O(M{sub N}{sup 2}/M{sub {pi}}{sup 3}); (b) perform the heavy-baryon expansion of the transverse densities; (c) explain the relative magnitude of the peripheral charge and magnetization densities in a simple mechanical picture; (d) include Delta isobar intermediate states and study the peripheral transverse densities in the large-N{ sub c} limit of QCD; (e) quantify the region of transverse distances where the chiral components of the densities are numerically dominant; (f) calculate the chiral divergences of the b{sup 2}-weighted moments of the isovector transverse densities (charge and anomalous magnetic radii) in the limit M{sub {pi}} -> 0 and determine their spatial support. Our approach provides a concise formulation of the spatial structure of the nucleon's chiral component and offers new insights into basic properties of the chiral expansion. It relates the information extracted from low-t elastic form factors to the generalized parton distributions probed in peripheral high-energy scattering processes.
Conribution to the study of spontaneous breakdown of the chiral symmetry in gauge theories
International Nuclear Information System (INIS)
Gamonal, R.
1984-01-01
In the framework of quantum chromodynamics, we have been interested in the order parameters for the breakdown of the non-abelian chiral symmetry. Using the functional integral representation in the euclidean formalism, we have performed the fermionic integration after having inverted the chiral limit and the integration over gluonic fields. So, we were led to look for what gauge field configurations, the fermionic integrand has a non-vanishing chiral limit. We have been able to show, in a general manner, that the generating functional of all the order parameters vanishes in the chiral limit for the gauge field configurations which lead to a discrete spectrum for the Dirac operator around zero. For those leading to a continuous spectrum from the zero eigenvalue, the existence of a non-vanishing infra-red limit for the spectral density of the Dirac operator is crucial. We have exhibited gauge field configurations which give such a behaviour. Nevertheless, our analysis reveals the necessity to get a degeneracy for the zero modes belonging to the continuum of the Dirac operator. We have been able to demonstrate, for the class of gluonic fields, previously considered, an absence of degeneracy [fr
Analysis of K → 3π decays in chiral perturbation theory
International Nuclear Information System (INIS)
Cheng Haiyang; Cheung, C.Y.; Yeung Waibong
1989-01-01
Using the recently proposed higher-order chiral Lagrangians determined from the integration of nontopological chiral anomalies, we calculate corrections to the current-algebra analysis of K→3π decay amplitudes expanded in powers of the Dalitz variables. Effects of quartic-derivative weak chiral Lagrangians are determined through the use of short-distance effective weak Hamiltonian and the factorization method. We find that (1) the constant and linear terms in the amplitude for ΔI=1/2 K→3π are in excellent agreement with experiment; the previous discrepancy of (20-35)% between current algebra and data is thus accounted for by the higher-order effective Lagrangians, (2) the penguin interaction does not play an essential role in the ΔI=1/2 rule, for otherwise it will lead to a large disagreement for the constant and linear terms, (3) one of the two quadratic terms in the ΔI=1/2 process, which arise from the quartic chiral Lagrangians, is in accord with data within experimental errors, while the other is off by four standard deviations, (4) the linear term in the ΔI=3/2 transitions is in good agreement with experiment and contributions from quadratic terms are sizable. (orig.)
θ-parameter evolution and topological-charge matching conditions in chiral-color theory
International Nuclear Information System (INIS)
Frampton, P.H.; Kephart, T.W.
1991-01-01
The θ parameter and topological charges are followed through spontaneous-symmetry-breaking phase transitions. The most interesting case is that of an irregular embedding of SU(3) C in a spontaneously broken larger group. The example of chiral color is shown to have no additional CP difficulties beyond the SU(3) C CP problem
Analysis of ''new physics'' in the flavor sector using effective field theory methods
Energy Technology Data Exchange (ETDEWEB)
Dassinger, Benjamin M.
2010-02-05
The enormous amount of data collected by the B factories as well as the perspective concerning the upcoming experiments at the LHC provide us with the opportunity to perform high precision tests of the standard model. This dissertation presents two model independent precision tests of the weak sector of the standard model using extensions of the weak currents which are set up using effective field theory methods in order to control the size of the different contributions. Constraints on the coefficients of the terms can then be obtained by comparison with experimental results. The first analysis incorporates a test of the lefthandedness of the weak interaction in the quark sector. By introducing additional weak couplings the differential and total decay rates of the inclusive semileptonic decay anti B {yields} X{sub c}l anti {nu}{sub l} are calculated. The calculation includes the computation of the heavy-quark expansion which describes the interaction of the decaying b quark with respect to the background field of the B meson, up to order 1/m{sub b}{sup 4}. This has been done in a new, systematic way which does not involve the calculation of gluon matrix elements. Furthermore, radiative corrections have been included up to order O({alpha}{sub s}) including renormalization group running. The second part deals with the introduction of lepton flavor violating operators in the context of leptonic {tau} decays. These operators give rise to the effective four-fermion vertex {tau}{yields}ll{sup '}l'' as well as the subsequent radiative decay {tau}{yields}l{gamma}{sup *}{yields}ll{sup '+}l{sup '-}. The resulting Dalitz distributions turn out to predict completely different signatures for the radiative and the effective four-fermion vertices and provide the opportunity to check, whether the decay is induced either by a radiative or by an effective four-fermion vertex. Since different models which contain lepton flavor violation are normally more
The Fuzzy analogy of chiral diffeomorphisms in higher dimensional quantum field theories
International Nuclear Information System (INIS)
Fassarella, Lucio; Schroer, Bert
2001-06-01
Our observation that the chiral diffeomorphisms allow an interpretation as modular groups of local operator algebras in the sense of Tomita and takesaki allows us to conclude that the higher deimensional generalizations are certain infinite dimensional groups which act in a 'fuzzy' way on the operator algebras of local quantum physics. These actions do not require any spacetime noncommutativity and are in complete harmony with causality and localization principles. The use of an appropriately defined isomorphism reprocesses these fuzzy actions into partially geometric actions on the holographic image and in this way tightens the relation with chiral structures and makes recent attempts to explain the required universal structure of a would be quantum Bekenstein law in terms of Virasoro algebra structures more palatable. (author)
Energy Technology Data Exchange (ETDEWEB)
Levi, Michele [Institut d' Astrophysique de Paris, Université Pierre et Marie Curie, CNRS-UMR 7095, 98 bis Boulevard Arago, 75014 Paris (France); Steinhoff, Jan, E-mail: michele.levi@upmc.fr, E-mail: jan.steinhoff@ist.utl.pt [Centro Multidisciplinar de Astrofisica, Instituto Superior Tecnico, Universidade de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal)
2014-12-01
The next-to-next-to-leading order spin1-spin2 potential for an inspiralling binary, that is essential for accuracy to fourth post-Newtonian order, if both components in the binary are spinning rapidly, has been recently derived independently via the ADM Hamiltonian and the Effective Field Theory approaches, using different gauges and variables. Here we show the complete physical equivalence of the two results, thereby we first prove the equivalence of the ADM Hamiltonian and the Effective Field Theory approaches at next-to-next-to-leading order with the inclusion of spins. The main difficulty in the spinning sectors, which also prescribes the manner in which the comparison of the two results is tackled here, is the existence of redundant unphysical spin degrees of freedom, associated with the spin gauge choice of a point within the extended spinning object for its representative worldline. After gauge fixing and eliminating the unphysical degrees of freedom of the spin and its conjugate at the level of the action, we arrive at curved spacetime generalizations of the Newton-Wigner variables in closed form, which can also be used to obtain further Hamiltonians, based on an Effective Field Theory formulation and computation. Finally, we make use of our validated result to provide gauge invariant relations among the binding energy, angular momentum, and orbital frequency of an inspiralling binary with generic compact spinning components to fourth post-Newtonian order, including all known sectors up to date.
S-wave Kπ scattering in chiral perturbation theory with resonances
International Nuclear Information System (INIS)
Jamin, Matthias; Oller, Jose Antonio; Pich, Antonio
2000-01-01
We present a detailed analysis of S-wave Kπ scattering up to 2 GeV, making use of the resonance chiral Lagrangian predictions together with a suitable unitarisation method. Our approach incorporates known theoretical constraints at low and high energies. The present experimental status, with partly conflicting data from different experiments, is discussed. Our analysis allows to resolve some experimental ambiguities, but better data are needed in order to determine the cross-section in the higher-energy range. Our best fits are used to determine the masses and widths of the relevant scalar resonances in this energy region
Beem, Christopher; Rastelli, Leonardo; van Rees, Balt C.
2015-01-01
Four-dimensional N=2 superconformal field theories have families of protected correlation functions that possess the structure of two-dimensional chiral algebras. In this paper, we explore the chiral algebras that arise in this manner in the context of theories of class S. The class S duality web implies nontrivial associativity properties for the corresponding chiral algebras, the structure of which is best summarized in the language of generalized topological quantum field theory. We make a number of conjectures regarding the chiral algebras associated to various strongly coupled fixed points.
International Nuclear Information System (INIS)
Seo, K.
1990-01-01
Fermion one-loop corrections to the commutators of the gauge field, the electric field, and the charge density with the total Hamiltonian are evaluated by the Bjorken-Johnson-Low method in chiral gauge theories. It turns out that individual terms of the Hamiltonian give anomalous terms to the commutator with the electric field, but the total Hamiltonian does not. That is, the classical equation of motion for the electric field holds as the Heisenberg equation. The current-divergence anomaly is identified with the anomalous terms of the commutator between the charge density and the total Hamiltonian. These two results are combined to show that the time derivative of the Gauss-law operator amounts to the current-divergence anomaly (Fujikawa's relation)
The Electric Dipole Form Factor of the Nucleon in Chiral Perturbation Theory to Sub-leading Order
Mereghetti, E; Hockings, W H; Maekawa, C M; van Kolck, U
2011-01-01
The electric dipole form factor (EDFF) of the nucleon stemming from the QCD theta term and from the quark color-electric dipole moments is calculated in chiral perturbation theory to sub-leading order. This is the lowest order in which the isoscalar EDFF receives a calculable, non-analytic contribution from the pion cloud. In the case of the theta term, the expected lower bound on the deuteron electric dipole moment is |d_d| > 1.4 10^(-4) \\theta e fm. The momentum dependence of the isovector EDFF is proportional to a non-derivative time-reversal-violating pion-nucleon coupling, and the scale for momentum variation ---appearing, in particular, in the radius of the form factor--- is the pion mass.
International Nuclear Information System (INIS)
Kulshreshtha, U.
1998-01-01
A chiral Schwinger model with the Faddeevian regularization a la Mitra is studied in the light-front frame. The front-form theory is found to be gauge-non-invariant. The Hamiltonian formulation of this gauge-non-invariant theory is first investigated and then the Stueckelberg term for this theory is constructed. Finally, the Hamiltonian and BRST formulations of the resulting gauge-invariant theory, obtained by the inclusion of the Stueckelberg term in the action of the above gauge-non-invariant theory, are investigated with some specific gauge choices. (orig.)
MAXWELL’S THEORY WITH CHIRAL CURRENTS TEORÍA DE MAXWELL CON CORRIENTES QUIRALES
Directory of Open Access Journals (Sweden)
Héctor Torres-Silva
2008-11-01
Full Text Available The energy and momentum content of an electromagnetic field can be expressed entirely in terms of the fields through the energy-momentum tensor with no mention of the sources creating the fields. This tensor is defined such that chiral currents are introduced. In the case of free force we have and . This approach allows for a very symmetric derivation of the energy and momentum content of the fields with . This configuration is essential to the unification of electromagnetism and gravity, obtaining a force-free configuration for the electron. To obtain this unification the Rainich geometrization under chiral conditions is discussed.El contenido de energía y momento de un campo electromagnético puede ser expresado enteramente, en términos de los campos a través del tensor energía momento, sin mención de las fuentes que crean los campos. Este tensor es definido introduciendo corrientes quirales. En el caso de sin fuerza se tiene y . Este método permite una muy simétrica derivación del contenido de energía y momento de los campos con . Esta configuración es esencial para la unificación del electromagnetismo y la gravedad, obteniendo una configuración de fuerza cero para el electrón. Para obtener esta unificación se discute la geometrización de Rainich bajo condiciones quirales.
Chiral Symmetry Restoration, Naturalness and the Absence of Fine-Tuning I: Global Theories
Lynn, Bryan W.
2013-01-01
The Standard Model (SM), and the scalar sector of its zero-gauge-coupling limit -- the chiral-symmetric limit of the Gell Mann-Levy Model (GML) -- have been shown not to suffer from a Higgs Fine-Tuning (FT) problem. All ultraviolet quadratic divergences (UVQD) are absorbed into the mass-squared of pseudo Nambu-Goldstone (pNGB) bosons, in GML. Since chiral SU(2)_{L-R} symmetry is restored as the pNGB mass-squared or as the Higgs vacuum expectation value (VEV) are taken to 0, small values of these quantities and of the Higgs mass are natural, and therefore not Fine-Tuned. In this letter, we extend our results on the absence of FT to a wide class of high-mass-scale (M_{Heavy}>>m_{Higgs}) extensions to a simplified SO(2) version of GML. We explicitly demonstrate naturalness and no-FT for two examples of heavy physics, both SO(2) singlets: a heavy (M_S >> m_{Higgs}) real scalar field (with or without a VEV); and a right-handed Type 1 See-Saw Majorana neutrino with M_R >> m_{Higgs}. We prove that for |q^2| <<...
Goings, Joshua James
Time-dependent electronic structure theory has the power to predict and probe the ways electron dynamics leads to useful phenomena and spectroscopic data. Here we report several advances and extensions of broken-symmetry time-dependent electronic structure theory in order to capture the flexibility required to describe non-equilibrium spin dynamics, as well as electron dynamics for chiroptical properties and vibrational effects. In the first half, we begin by discussing the generalization of self-consistent field methods to the so-called two-component structure in order to capture non-collinear spin states. This means that individual electrons are allowed to take a superposition of spin-1/2 projection states, instead of being constrained to either spin-up or spin-down. The system is no longer a spin eigenfunction, and is known a a spin-symmetry broken wave function. This flexibility to break spin symmetry may lead to variational instabilities in the approximate wave function, and we discuss how these may be overcome. With a stable non-collinear wave function in hand, we then discuss how to obtain electronic excited states from the non-collinear reference, along with associated challenges in their physical interpretation. Finally, we extend the two-component methods to relativistic Hamiltonians, which is the proper setting for describing spin-orbit driven phenomena. We describe the first implementation of the explicit time propagation of relativistic two-component methods and how this may be used to capture spin-forbidden states in electronic absorption spectra. In the second half, we describe the extension of explicitly time-propagated wave functions to the simulation of chiroptical properties, namely circular dichroism (CD) spectra of chiral molecules. Natural circular dichroism, that is, CD in the absence of magnetic fields, originates in the broken parity symmetry of chiral molecules. This proves to be an efficient method for computing circular dichroism spectra
The scalar and electromagnetic form factors of the nucleon in dispersively improved Chiral EFT
Energy Technology Data Exchange (ETDEWEB)
Alarcon, Jose Manuel [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2018-04-01
We present a method for calculating the nucleon form factors of G-parity-even operators. This method combines chiral effective field theory (χEFT) and dispersion theory. Through unitarity we factorize the imaginary part of the form factors into a perturbative part, calculable with χEFT, and a non-perturbative part, obtained through other methods. We consider the scalar and electromagnetic (EM) form factors of the nucleon. The results show an important improvement compared to standard chiral calculations, and can be used in analysis of the low-energy properties of the nucleon.
Yamamoto, Takuya; Nishigaki, Shinsuke M.
2018-02-01
We compute individual distributions of low-lying eigenvalues of a chiral random matrix ensemble interpolating symplectic and unitary symmetry classes by the Nyström-type method of evaluating the Fredholm Pfaffian and resolvents of the quaternion kernel. The one-parameter family of these distributions is shown to fit excellently the Dirac spectra of SU(2) lattice gauge theory with a constant U(1) background or dynamically fluctuating U(1) gauge field, which weakly breaks the pseudoreality of the unperturbed SU(2) Dirac operator. The observed linear dependence of the crossover parameter with the strength of the U(1) perturbations leads to precise determination of the pseudo-scalar decay constant, as well as the chiral condensate in the effective chiral Lagrangian of the AI class.
Extension of the chiral perturbation theory meson Lagrangian to order p{sup 6}
Energy Technology Data Exchange (ETDEWEB)
Fearing, H W; Scherer, S
1994-08-01
We have derived the most general chirally invariant Lagrangian L{sub 6} for the meson sector at order p{sup 6}. The result provides an extension of the standard Gasser-Leutwyler Lagrangian L{sub 4} to one higher order, including as well all the odd intrinsic parity terms in the Lagrangian. The most difficult part of the derivation was developing a systematic strategy so as to get all of the independent terms and eliminate the redundant ones in an efficient way. The equation of motion terms, which are redundant in the sense that they can be transformed away via field transformations, are separated out explicitly. The resulting Lagrangian has been separated into groupings of terms contributing to increasingly more complicated processes, so that one does not have to deal with the full result when calculating p{sup 6} contributions to simple processes. (author). 53 refs., 10 tabs.
Energy Technology Data Exchange (ETDEWEB)
Bourget, Antoine; Troost, Jan [Laboratoire de Physique Théorique, École Normale Supérieure, 24 rue Lhomond, 75005 Paris (France)
2016-03-23
We construct a covariant generating function for the spectrum of chiral primaries of symmetric orbifold conformal field theories with N=(4,4) supersymmetry in two dimensions. For seed target spaces K3 and T{sup 4}, the generating functions capture the SO(21) and SO(5) representation theoretic content of the chiral ring respectively. Via string dualities, we relate the transformation properties of the chiral ring under these isometries of the moduli space to the Lorentz covariance of perturbative string partition functions in flat space.
Energy Technology Data Exchange (ETDEWEB)
Levi, Michele [Université Pierre et Marie Curie, CNRS-UMR 7095, Institut d' Astrophysique de Paris, 98 bis Boulevard Arago, 75014 Paris (France); Steinhoff, Jan, E-mail: michele.levi@upmc.fr, E-mail: jan.steinhoff@aei.mpg.de [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute), Am Mühlenberg 1, 14476 Potsdam-Golm (Germany)
2016-01-01
The next-to-next-to-leading order spin-squared interaction potential for generic compact binaries is derived for the first time via the effective field theory for gravitating spinning objects in the post-Newtonian scheme. The spin-squared sector is an intricate one, as it requires the consideration of the point particle action beyond minimal coupling, and mainly involves the spin-squared worldline couplings, which are quite complex, compared to the worldline couplings from the minimal coupling part of the action. This sector also involves the linear in spin couplings, as we go up in the nonlinearity of the interaction, and in the loop order. Hence, there is an excessive increase in the number of Feynman diagrams, of which more are higher loop ones. We provide all the Feynman diagrams and their values. The beneficial ''nonrelativistic gravitational'' fields are employed in the computation. This spin-squared correction, which enters at the fourth post-Newtonian order for rapidly rotating compact objects, completes the conservative sector up to the fourth post-Newtonian accuracy. The robustness of the effective field theory for gravitating spinning objects is shown here once again, as demonstrated in a recent series of papers by the authors, which obtained all spin dependent sectors, required up to the fourth post-Newtonian accuracy. The effective field theory of spinning objects allows to directly obtain the equations of motion, and the Hamiltonians, and these will be derived for the potential obtained here in a forthcoming paper.
Compton scattering on the proton, neutron, and deuteron in chiral perturbation theory to O(Q{sup 4})
Energy Technology Data Exchange (ETDEWEB)
S.R. Beane; M. Malheiro; J.A. McGovern; D.R. Phillips; U. van Kolck
2004-03-01
We study Compton scattering in systems with A=1 and 2 using chiral perturbation theory up to fourth order. For the proton we fit the two undetermined parameters in the O(Q{sup 4}) {gamma}p amplitude of McGovern to experimental data in the region {omega}, {radical}|t| {le} 180 MeV, obtaining a {chi}{sup 2}/d.o.f. of 133/113. This yields a model-independent extraction of proton polarizabilities based solely on low-energy data: {alpha}{sub p} = (12.1 {+-} 1.1 (stat.)){sub -0.5}{sup +0.5} (theory) and {beta}{sub p} = (3.4 {+-} 1.1 (stat.)){sub -0.1}{sup +0.1} (theory), both in units of 10{sup -4} fm{sup 3}. We also compute Compton scattering on deuterium to O(Q{sup 4}). The {gamma}d amplitude is a sum of one- and two-nucleon mechanisms, and contains two undetermined parameters, which are related to the isoscalar nucleon polarizabilities. We fit data points from three recent {gamma}d scattering experiments with a {chi}{sup 2}/d.o.f. = 26.3/20, and find {alpha}{sub N} = 8.9 {+-} 1.5 (stat.){sub -0.9}{sup +4.7} (theory) and {beta}{sub N} = 2.2 {+-} 1.5 (stat.){sub -0.9}{sup +1.2} (theory), again in units of 10{sup -4} fm{sup 3}.
International Nuclear Information System (INIS)
Cakir, M.B.
1993-01-01
In the first part of this dissertation a search for light gluinos in the 0(1 GeV) region - especially in radiative decays of vector quarkonia - is presented. It is shown that light gluinos have not been excluded by experiments to date. In fact some evidence contrary to that fact is presented. In the second part the recent Heavy Quark Effective Field Theory methods are used in calculating rare decays of vector and pseudoscalar mesons of b-quarks. Applications to the Collider Detector at Fermilab environment are discussed
Unified chiral analysis of the vector meson spectrum from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Wes Armour; Chris Allton; Derek Leinweber; Anthony Thomas; Ross Young
2005-10-13
The chiral extrapolation of the vector meson mass calculated in partially-quenched lattice simulations is investigated. The leading one-loop corrections to the vector meson mass are derived for partially-quenched QCD. A large sample of lattice results from the CP-PACS Collaboration is analysed, with explicit corrections for finite lattice spacing artifacts. To incorporate the effect of the opening decay channel as the chiral limit is approached, the extrapolation is studied using a necessary phenomenological extension of chiral effective field theory. This chiral analysis also provides a quantitative estimate of the leading finite volume corrections. It is found that the discretisation, finite-volume and partial quenching effects can all be very well described in this framework, producing an extrapolated value of $M_\\rho$ in excellent agreement with experiment. This procedure is also compared with extrapolations based on polynomial forms, where the results are much less enlightening.
Parameterization of general Z-γ-Z' mixing in an electroweak chiral theory
International Nuclear Information System (INIS)
Zhang Ying; Wang Qing
2012-01-01
A new general parameterization with eight mixing parameters among Z, γ and an extra neutral gauge boson Z ' is proposed and subjected to phenomenological analysis. We show that in addition to the conventional Weinberg angle θ W , there are seven other phenomenological parameters, G ' , ξ, η, θ 1 , θ r , r and l, for the most general Z-γ-Z ' mixings, in which parameter G ' arises due to the presence of an extra Stueckelbergtype mass coupling. Combined with the conventional Z-Z ' mass mixing angle 0', the remaining six parameters, ξ, η, θ l -θ ' , θ r - θ ' , r and l, are caused by general kinetic mixing. In all eight phenomenological parameters, θ W , G ' , ξ, η, θ 1 , θ r , r and l, we can determine the Z-Z ' mass mixing angle θ ' and the mass ratio M Z /M Z ' . The Z-γ-Z ' mixing that we discuss are based on the model-independent description of the extended electroweak chiral Lagrangian (EWCL) previously proposed by us. In addition, we show that there are eight corresponding independent theoretical coefficients in our EWCL, which are fully fixed by our eight phenomenological mixing parameters. We further find that the experimental measurability of these eight parameters does not rely on the extended neutral current for Z ' , but depends on the Z-Z ' mass ratio. (authors)
Extension of the chiral perturbation theory meson Lagrangian to order p6
International Nuclear Information System (INIS)
Fearing, H.W.; Scherer, S.
1996-01-01
We have constructed the most general chirally invariant Lagrangian scrL 6 for the meson sector at order p 6 . The result provides an extension of the standard Gasser-Leutwyler Lagrangian scrL 4 to one higher order, including as well all the odd intrinsic parity terms in the Lagrangian. The most difficult part of the construction was developing a systematic strategy so as to get all of the independent terms and eliminate the redundant ones in an efficient way. The claim to have obtained the most general Lagrangian relies on this systematic construction and on the elimination of redundant quantities using relations of which we are aware, rather than on a general formal proof of either completeness or independence. The open-quote open-quote equation-of-motion close-quote close-quote terms, which are redundant in the sense that they can be transformed away via field transformations, are separated out explicitly. The resulting Lagrangian has been separated into groupings of terms contributing to increasingly more complicated processes, so that one does not have to deal with the full result when calculating p 6 contributions to simple processes. copyright 1995 The American Physical Society
Energy Technology Data Exchange (ETDEWEB)
Ertaş, Mehmet [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Kocakaplan, Yusuf [Institute of Science, Erciyes University, 38039 Kayseri (Turkey); Keskin, Mustafa, E-mail: keskin@erciyes.edu.tr [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)
2013-12-15
Dynamic phase diagrams are presented for the kinetic spin-3/2 Blume–Capel model under a time oscillating longitudinal field by use of the effective-field theory with correlations. The dynamic equation of the average magnetization is obtained for the square lattice by utilizing the Glauber-type stochastic process. Dynamic phase diagrams are presented in the reduced temperature and the magnetic field amplitude plane. We also investigated the effect of longitudinal field frequency. Finally, the discussion and comparison of the phase diagrams are given. - Highlights: • Dynamic behaviors in the spin-3/2 Blume–Capel system is investigated by the effective-field theory based on the Glauber-type stochastic dynamics. • The dynamic phase transitions and dynamic phase diagrams are obtained. • The effects of the longitudinal field frequency on the dynamic phase diagrams of the system are investigated. • Dynamic phase diagrams exhibit several ordered phases, coexistence phase regions and several critical points as well as a re-entrant behavior.
International Nuclear Information System (INIS)
Ertaş, Mehmet; Kocakaplan, Yusuf; Keskin, Mustafa
2013-01-01
Dynamic phase diagrams are presented for the kinetic spin-3/2 Blume–Capel model under a time oscillating longitudinal field by use of the effective-field theory with correlations. The dynamic equation of the average magnetization is obtained for the square lattice by utilizing the Glauber-type stochastic process. Dynamic phase diagrams are presented in the reduced temperature and the magnetic field amplitude plane. We also investigated the effect of longitudinal field frequency. Finally, the discussion and comparison of the phase diagrams are given. - Highlights: • Dynamic behaviors in the spin-3/2 Blume–Capel system is investigated by the effective-field theory based on the Glauber-type stochastic dynamics. • The dynamic phase transitions and dynamic phase diagrams are obtained. • The effects of the longitudinal field frequency on the dynamic phase diagrams of the system are investigated. • Dynamic phase diagrams exhibit several ordered phases, coexistence phase regions and several critical points as well as a re-entrant behavior
International Nuclear Information System (INIS)
Ma Zhongshui; Su Zhaobin.
1992-09-01
By applying the Dirac quantization method, we build the constraint that all electrons are in the lowest Landau level into the Chern-Simons field theory approach for the fractional quantum Hall system and show that the constraint can be transmuted from hierarchy to hierarchy. For a finite system, we derive that the action for each hierarchy can be split into two parts: a surface part provides the action for the edge excitations while the remaining part is precisely the bulk action for the next hierarchy. An the action for the edge could be decoupled from the bulk only at the hierarchy filling. (author). 16 refs
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Franke, J.-H.; Kosov, D. S. [Department of Physics, Campus Plaine - CP 231, Universite Libre de Bruxelles, 1050 Brussels (Belgium)
2015-01-28
We study the adsorption and ring-opening of lactide on the naturally chiral metal surface Pt(321){sup S}. Lactide is a precursor for polylactic acid ring-opening polymerization, and Pt is a well known catalyst surface. We study, here, the energetics of the ring-opening of lactide on a surface that has a high density of kink atoms. These sites are expected to be present on a realistic Pt surface and show enhanced catalytic activity. The use of a naturally chiral surface also enables us to study potential chiral selectivity effects of the reaction at the same time. Using density functional theory with a functional that includes the van der Waals forces in a first-principles manner, we find modest adsorption energies of around 1.4 eV for the pristine molecule and different ring-opened states. The energy barrier to be overcome in the ring-opening reaction is found to be very small at 0.32 eV and 0.30 eV for LL- and its chiral partner DD-lactide, respectively. These energies are much smaller than the activation energy for a dehydrogenation reaction of 0.78 eV. Our results thus indicate that (a) ring-opening reactions of lactide on Pt(321) can be expected already at very low temperatures, and Pt might be a very effective catalyst for this reaction; (b) the ring-opening reaction rate shows noticeable enantioselectivity.
Yao, De-Liang
2018-02-01
We calculate the masses and sigma terms of the doubly charmed baryons up to next-to-next-to-next-to-leading order [i.e., O (p4) ] in a covariant baryon chiral perturbation theory by using the extended-on-mass-shell renormalization scheme. Their expressions both in infinite and finite volumes are provided for chiral extrapolation in lattice QCD. As a first application, our chiral results of the masses are confronted with the existing lattice QCD data in the presence of finite-volume corrections. Up to O (p3) , all relevant low-energy constants can be well determined. As a consequence, we obtain the physical values for the masses of Ξc c and Ωc c baryons by extrapolating to the physical limit. Our determination of the Ξc c mass is consistent with the recent experimental value by LHCb Collaboration, however, larger than the one by SELEX Collaboration. In addition, we predict the pion-baryon and strangeness-baryon sigma terms, as well as the mass splitting between the Ξc c and Ωc c states. Their quark mass dependences are also discussed. The numerical procedure can be applied to the chiral results of O (p4) order, where more unknown constants are involved, when more data are available for unphysical pion masses.
Perturbative renormalizability of chiral two-pion exchange in nucleon-nucleon scattering
International Nuclear Information System (INIS)
Pavon Valderrama, M.
2011-01-01
We study the perturbative renormalizability of chiral two-pion exchange for singlet and triplet channels within effective field theory, provided that the one-pion exchange piece of the interaction has been fully iterated. We determine the number of counterterms/subtractions needed to obtain finite results when the cutoff is removed, resulting in three counterterms for the singlet channel and six for the triplet. The results show that perturbative chiral two-pion exchange reproduce the data up to a center-of-mass momentum of k∼200-300 MeV in the singlet channel and k∼300-400 MeV in the triplet.
Energy Technology Data Exchange (ETDEWEB)
Vasconcellos, C. A. Zen, E-mail: cesarzen@cesarzen.com [Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, 91501-970, Porto Alegre (Brazil); International Center for Relativistic Astrophysics Network (ICRANet), Piazza della Repubblica 10, 65122 Pescara (Italy)
2015-12-17
Nuclear science has developed many excellent theoretical models for many-body systems in the domain of the baryon-meson strong interaction for the nucleus and nuclear matter at low, medium and high densities. However, a full microscopic understanding of nuclear systems in the extreme density domain of compact stars is still lacking. The aim of this contribution is to shed some light on open questions facing the nuclear many-body problem at the very high density domain. Here we focus our attention on the conceptual issue of naturalness and its role in shaping the baryon-meson phase space dynamics in the description of the equation of state (EoS) of nuclear matter and neutrons stars. In particular, in order to stimulate possible new directions of research, we discuss relevant aspects of a recently developed relativistic effective theory for nuclear matter within Quantum Hadrodynamics (QHD) with genuine many-body forces and derivative natural parametric couplings. Among other topics we discuss in this work the connection of this theory with other known effective QHD models of the literature and its potentiality in describing a new physics for dense matter. The model with parameterized couplings exhausts the whole fundamental baryon octet (n, p, Σ{sup −}, Σ{sup 0}, Σ{sup +}, Λ, Ξ{sup −}, Ξ{sup 0}) and simulates n-order corrections to the minimal Yukawa baryon couplings by considering nonlinear self-couplings of meson fields and meson-meson interaction terms coupled to the baryon fields involving scalar-isoscalar (σ, σ∗), vector-isoscalar (ω, Φ), vector-isovector (ϱ) and scalar-isovector (δ) virtual sectors. Following recent experimental results, we consider in our calculations the extreme case where the Σ{sup −} experiences such a strong repulsion that its influence in the nuclear structure of a neutron star is excluded at all. A few examples of calculations of properties of neutron stars are shown and prospects for the future are discussed.
International Nuclear Information System (INIS)
Hinterbichler, Kurt; Joyce, Austin; Khoury, Justin
2012-01-01
The pseudo-conformal scenario is an alternative to inflation in which the early universe is described by an approximate conformal field theory on flat, Minkowski space. Some fields acquire a time-dependent expectation value, which breaks the flat space so(4,2) conformal algebra to its so(4,1) de Sitter subalgebra. As a result, weight-0 fields acquire a scale invariant spectrum of perturbations. The scenario is very general, and its essential features are determined by the symmetry breaking pattern, irrespective of the details of the underlying microphysics. In this paper, we apply the well-known coset technique to derive the most general effective lagrangian describing the Goldstone field and matter fields, consistent with the assumed symmetries. The resulting action captures the low energy dynamics of any pseudo-conformal realization, including the U(1)-invariant quartic model and the Galilean Genesis scenario. We also derive this lagrangian using an alternative method of curvature invariants, consisting of writing down geometric scalars in terms of the conformal mode. Using this general effective action, we compute the two-point function for the Goldstone and a fiducial weight-0 field, as well as some sample three-point functions involving these fields
Pion polarizability in a chiral quark model
International Nuclear Information System (INIS)
Volkov, M.K.; Ehbert, D.
1980-01-01
The pion polarizability is calculated in a chiral meson-quark model at the one-loop level. The results are in complete agreement with earlier ones obtained within a chiral meson-baryon theory. A critical discussion of a recent paper by Lanta and Tarrach is given. The results of the paper give evidence to the nonlinear chiral Lagrangian favour
Chiral symmetry breaking in asymptotically free and non-asymptotically free gauge theories
International Nuclear Information System (INIS)
Gusynin, V.P.; Miranskij, V.A.
1986-01-01
An essential distinction in the realization of the PCAC-dynamics in vector-like asymptotically free and non-asymptotically free (with a non-trival ultraviolet stable fixed point) gauge theories is revealed. For the latter theories an analytical expression for the condensate is obtained in the two-loop approximation and the arguments in support of a soft behaviour at small distances of composite operators are given. The problem of factorizing the low-energy region for the Wess-Zumino-Witten action is discussed
Energy Technology Data Exchange (ETDEWEB)
Ertas, Mehmet [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Institute of Science, Erciyes University, 38039 Kayseri (Turkey); Deviren, Bayram [Department of Physics, Nevsehir University, 50300 Nevsehir (Turkey); Keskin, Mustafa, E-mail: keskin@erciyes.edu.tr [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)
2012-03-15
The dynamic phase transitions are studied in the kinetic spin-2 Blume-Capel model under a time-dependent oscillating magnetic field using the effective-field theory with correlations. The effective-field dynamic equation for the average magnetization is derived by employing the Glauber transition rates and the phases in the system are obtained by solving this dynamic equation. The nature (first- or second-order) of the dynamic phase transition is characterized by investigating the thermal behavior of the dynamic magnetization and the dynamic phase transition temperatures are obtained. The dynamic phase diagrams are constructed in the reduced temperature and magnetic field amplitude plane and are of seven fundamental types. Phase diagrams contain the paramagnetic (P), ferromagnetic-2 (F{sub 2}) and three coexistence or mixed phase regions, namely the F{sub 2}+P, F{sub 1}+P and F{sub 2}+F{sub 1}+P, which strongly depend on the crystal-field interaction (D) parameter. The system also exhibits the dynamic tricritical behavior. - Highlights: Black-Right-Pointing-Pointer Dynamic phase transitions are studied in spin-2 BC model using EFT. Black-Right-Pointing-Pointer Dynamic phase diagrams are constructed in (T/zJ, h/zJ) plane. Black-Right-Pointing-Pointer Seven fundamental types of dynamic phase diagrams are found in the system. Black-Right-Pointing-Pointer System exhibits dynamic tricritical behavior.
International Nuclear Information System (INIS)
Deviren, Bayram; Kantar, Ersin; Keskin, Mustafa
2010-01-01
The magnetic properties of the ferrimagnetic mixed spin-3/2 and spin-2 Ising model with a crystal field in a longitudinal magnetic field on a honeycomb (δ = 3) and a square lattice (δ = 4) are studied by using the effective-field theory with correlations. The ground-state phase diagram of the model is obtained in a longitudinal magnetic field (h) for a single-ion potential or a crystal-field interaction (Δ) plane. We also investigate the thermal variations of the sublattice magnetization, and present the phase diagrams in the (Δ/|J|, k B T/|J|) plane. The susceptibility, internal energy, and specific heat of the system are numerically examined, and some interesting phenomena in these quantities are found due to the applied longitudinal magnetic field. Moreover, the system undergoes first- and second-order phase transitions; hence, the system has a tricritical point. The system also exhibits reentrant behaviors.
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Deviren, Bayram [Nevsehir University, Nevsehir (Turkmenistan); Kantar, Ersin; Keskin, Mustafa [Erciyes University, Kayseri (Turkmenistan)
2010-06-15
The magnetic properties of the ferrimagnetic mixed spin-3/2 and spin-2 Ising model with a crystal field in a longitudinal magnetic field on a honeycomb ({delta} = 3) and a square lattice ({delta} = 4) are studied by using the effective-field theory with correlations. The ground-state phase diagram of the model is obtained in a longitudinal magnetic field (h) for a single-ion potential or a crystal-field interaction ({Delta}) plane. We also investigate the thermal variations of the sublattice magnetization, and present the phase diagrams in the ({Delta}/|J|, k{sub B}T/|J|) plane. The susceptibility, internal energy, and specific heat of the system are numerically examined, and some interesting phenomena in these quantities are found due to the applied longitudinal magnetic field. Moreover, the system undergoes first- and second-order phase transitions; hence, the system has a tricritical point. The system also exhibits reentrant behaviors.
Chiral symmetry and eta, eta' → 3π decays. Grand unified theories
International Nuclear Information System (INIS)
Roiesnel, C.
1982-11-01
Two different topics related to symmetry breaking are discussed. First the eta, eta' → 3π decays are presented. The amplitudes eta, eta' → 3π are calculated with the square root threshold singularity induced by the strong pion-pion final state interaction properly taken into account. It is shown that the eta' → 3π decay rate depends sensitively upon an improved treatment of the pseudoscalar nonet mass matrix. Then symmetry-breaking effects in grand unified theories are discussed. The threshold effects in a spontaneously broken gauge theory are studied. In particular a computation of the symmetry-breaking effects in the SU(5) grand unified theory including those of the breaking of SU(2)xU(1) is presented. As an application a precise value of the superheavy gauge boson mass Mx is given. It is possible in SU(5) to define a natural effective weak angle theta w(μ) for any scale μ, below as well as above Mw, and the predicted curve for sin 2 theta w(μ) is given [fr
International Nuclear Information System (INIS)
Sharpe, S.R.
1992-04-01
I develop a diagrammatic method for calculating chiral logarithms in the quenched approximation. While not rigorous, the method is based on physically reasonable assumptions, which can be tested by numerical simulations. The main results are that, at leading order in the chiral expansion, (a) there are no chiral logarithms in quenched f π m u = m d ; (b) the chiral logarithms in B K and related kaon B-parameters are, for m d = m s the same in the quenched approximation as in the full theory (c) for m π and the condensate, there are extra chiral logarithms due to loops containing the η', which lead to a peculiar non-analytic dependence of these quantities on the bare quark mass. Following the work of Gasser and Leutwyler, I discuss how there is a predictable finite volume dependence associated with each chiral logarithm. I compare the resulting predictions with numerical results: for most quantities the expected volume dependence is smaller than the errors. but for B V and B A there is an observed dependence which is consistent with the predictions
International Nuclear Information System (INIS)
Ertaş, Mehmet; Kantar, Ersin; Keskin, Mustafa
2014-01-01
The dynamic phase transitions (DPTs) and dynamic phase diagrams of the kinetic spin-1/2 bilayer system in the presence of a time-dependent oscillating external magnetic field are studied by using Glauber-type stochastic dynamics based on the effective-field theory with correlations for the ferromagnetic/ferromagnetic (FM/FM), antiferromagnetic/ferromagnetic (AFM/FM) and antiferromagnetic/antiferromagnetic (AFM/AFM) interactions. The time variations of average magnetizations and the temperature dependence of the dynamic magnetizations are investigated. The dynamic phase diagrams for the amplitude of the oscillating field versus temperature were presented. The results are compared with the results of the same system within Glauber-type stochastic dynamics based on the mean-field theory. - Highlights: • The Ising bilayer system is investigated within the Glauber dynamics based on EFT. • The time variations of average order parameters to find phases are studied. • The dynamic phase diagrams are found for the different interaction parameters. • The system displays the critical points as well as a re-entrant behavior
Energy Technology Data Exchange (ETDEWEB)
Ertaş, Mehmet; Kantar, Ersin, E-mail: ersinkantar@erciyes.edu.tr; Keskin, Mustafa
2014-05-01
The dynamic phase transitions (DPTs) and dynamic phase diagrams of the kinetic spin-1/2 bilayer system in the presence of a time-dependent oscillating external magnetic field are studied by using Glauber-type stochastic dynamics based on the effective-field theory with correlations for the ferromagnetic/ferromagnetic (FM/FM), antiferromagnetic/ferromagnetic (AFM/FM) and antiferromagnetic/antiferromagnetic (AFM/AFM) interactions. The time variations of average magnetizations and the temperature dependence of the dynamic magnetizations are investigated. The dynamic phase diagrams for the amplitude of the oscillating field versus temperature were presented. The results are compared with the results of the same system within Glauber-type stochastic dynamics based on the mean-field theory. - Highlights: • The Ising bilayer system is investigated within the Glauber dynamics based on EFT. • The time variations of average order parameters to find phases are studied. • The dynamic phase diagrams are found for the different interaction parameters. • The system displays the critical points as well as a re-entrant behavior.
Chiral dynamics with (nonstrange quarks
Directory of Open Access Journals (Sweden)
Kubis Bastian
2017-01-01
Full Text Available We review the results and achievements of the project B.3. Topics addressed include pion photoproduction off the proton and off deuterium, three-flavor chiral perturbation theory studies, chiral symmetry tests in Goldstone boson decays, the development of unitarized chiral perturbation theory to next-to-leading order, the two-pole structure of the Λ(1405, the dynamical generation of the lowest S11 resonances, the theory of hadronic atoms and its application to various systems, precision studies in light-meson decays based on dispersion theory, the Roy–Steiner analysis of pion–nucleon scattering, a high-precision extraction of the elusive pion–nucleon σ-term, and aspects of chiral dynamics in few-nucleon systems.
International Nuclear Information System (INIS)
Frusciante, Noemi; Papadomanolakis, Georgios; Silvestri, Alessandra
2016-01-01
We present a generalization of the effective field theory (EFT) formalism for dark energy and modified gravity models to include operators with higher order spatial derivatives. This allows the extension of the EFT framework to a wider class of gravity theories such as Hořava gravity. We present the corresponding extended action, both in the EFT and the Arnowitt-Deser-Misner (ADM) formalism, and proceed to work out a convenient mapping between the two, providing a self contained and general procedure to translate a given model of gravity into the EFT language at the basis of the Einstein-Boltzmann solver EFTCAMB. Putting this mapping at work, we illustrate, for several interesting models of dark energy and modified gravity, how to express them in the ADM notation and then map them into the EFT formalism. We also provide for the first time, the full mapping of GLPV models into the EFT framework. We next perform a thorough analysis of the physical stability of the generalized EFT action, in absence of matter components. We work out viability conditions that correspond to the absence of ghosts and modes that propagate with a negative speed of sound in the scalar and tensor sector, as well as the absence of tachyonic modes in the scalar sector. Finally, we extend and generalize the phenomenological basis in terms of α-functions introduced to parametrize Horndeski models, to cover all theories with higher order spatial derivatives included in our extended action. We elaborate on the impact of the additional functions on physical quantities, such as the kinetic term and the speeds of propagation for scalar and tensor modes.
No chiral truncation of quantum log gravity?
Andrade, Tomás; Marolf, Donald
2010-03-01
At the classical level, chiral gravity may be constructed as a consistent truncation of a larger theory called log gravity by requiring that left-moving charges vanish. In turn, log gravity is the limit of topologically massive gravity (TMG) at a special value of the coupling (the chiral point). We study the situation at the level of linearized quantum fields, focussing on a unitary quantization. While the TMG Hilbert space is continuous at the chiral point, the left-moving Virasoro generators become ill-defined and cannot be used to define a chiral truncation. In a sense, the left-moving asymptotic symmetries are spontaneously broken at the chiral point. In contrast, in a non-unitary quantization of TMG, both the Hilbert space and charges are continuous at the chiral point and define a unitary theory of chiral gravity at the linearized level.
Bagchi, Arjun; Basu, Rudranil; Detournary, Stéphane; Parekh, Pulastya
2018-05-01
We propose a holographic duality between a 2 dimensional (2d) chiral superconformal field theory and a certain theory of supergravity in 3d with flatspace boundary conditions that is obtained as a double scaling limit of a parity breaking theory of supergravity. We show how the asymptotic symmetries of the bulk theory reduce from the "despotic" super Bondi-Metzner-Sachs algebra (or equivalently the inhomogeneous super Galilean conformal algebra) to a single copy of the super-Virasoro algebra in this limit and also reproduce the same reduction from a study of null vectors in the putative 2d dual field theory.
Energy Technology Data Exchange (ETDEWEB)
Alarcon, Jose Manuel [Mainz Univ. (Germany). Inst. fuer Kernphysik; Camalich, Jorge Martin [Department of Physics and Astronomy, University of Sussex, Brighton (United Kingdom); Oller, Jose Antonio [Murcia Univ. (Spain). Dept. de Fisica
2013-07-01
In this talk I present the community our recent determinations of σ{sub πN} and σ{sub s} employing covariant baryon chiral perturbation theory and updated experimental information. We show how these determinations overcome the difficulties that the old values of σ{sub πN}=45 MeV and y∼0.23 have when trying to explain the modern experiments regarding the nuclear structure and LQCD determinations. From our results, a new scenario emerges where σ{sub πN} and σ{sub s} are in good agreement with updated phenomenology and recent LQCD calculations.
Isospin breaking in chiral perturbation theory and the decays η → πlν and τ → ηπν
International Nuclear Information System (INIS)
Neufeld, H.; Rupertsberger, H.
1994-01-01
Violation of isospin due to m u ≠ m d and electromagnetism is discussed within the framework of the standard model. The decay η → πlν is calculated at the one-loop level in chiral perturbation theory including an estimate of the electromagnetic contributions. Adding all four decay channels, we obtain 2.0*10 -13 as a rather accurate upper bound for the branching ratio. We determine the leading meson resonance contributions to τ → ηπν predicting a branching ratio of 1.2*10 -5 . (authors)
Energy Technology Data Exchange (ETDEWEB)
Ricardo de Sousa, J. [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-000 Manaus, AM (Brazil); National Institute of Science and Technology for Complex Systems, 3000, Japiim, 69077-000 Manaus, AM (Brazil); Neto, Minos A., E-mail: minos@pq.cnpq.br [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-000 Manaus, AM (Brazil); Padilha, Igor T.; Salmon, Octavio D.R.; Viana, J. Roberto [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-000 Manaus, AM (Brazil)
2013-12-15
We have studied the anisotropic three-dimensional nearest-neighbor Ising model with competitive interactions in an uniform longitudinal magnetic field H. The model consists of ferromagnetic interactions J{sub z}=λ{sub 2}J{sub x} in the x(z) direction and antiferromagnetic interactions J{sub y}=λ{sub 1}J{sub x} in the y direction (Ising superantiferromagnet). For the particular case λ{sub 1}=λ{sub 2}=1 we obtain the phase diagram in the H−T plane, using the framework of the differential operator technique in the effective-field theory with finite cluster of N=4 spins (EFT-4). It was observed first- and second-order transitions in the low and high temperature limits, respectively, with the presence of a tricritical point and a reentrant behavior is observed at low temperature. The critical curve in the classical approach is also obtained and the results are compared.
International Nuclear Information System (INIS)
Deviren, Bayram; Polat, Yasin; Keskin, Mustafa
2011-01-01
The phase diagrams in the mixed spin-3/2 and spin-2 Ising system with two alternative layers on a honeycomb lattice are investigated and discussed by the use of the effective-field theory with correlations. The interaction of the nearest-neighbour spins of each layer is taken to be positive (ferromagnetic interaction) and the interaction of the adjacent spins of the nearest-neighbour layers is considered to be either positive or negative (ferromagnetic or anti-ferromagnetic interaction). The temperature dependence of the layer magnetizations of the system is examined to characterize the nature (continuous or discontinuous) of the phase transitions and obtain the phase transition temperatures. The system exhibits both second- and first-order phase transitions besides triple point (TP), critical end point (E), multicritical point (A), isolated critical point (C) and reentrant behaviour depending on the interaction parameters. We have also studied the temperature dependence of the total magnetization to find the compensation points, as well as to determine the type of behaviour, and N-type behaviour in Néel classification nomenclature existing in the system. The phase diagrams are constructed in eight different planes and it is found that the system also presents the compensation phenomena depending on the sign of the bilinear exchange interactions. (general)
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Buchalla, G.; Cata, O.; Rahn, R. [Muenchen Univ. (Germany). Fakultaet fuer Physik; Schlaffer, M. [Muenchen Univ. (Germany). Fakultaet fuer Physik; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2013-02-15
We analyze new physics contributions to e{sup +}e{sup -}{yields}W{sup +}W{sup -} at the TeV energy scale, employing an effective field theory framework. A complete basis of next-to-leading order operators in the standard model effective Lagrangian is used, both for the nonlinear and the linear realization of the electroweak sector. The elimination of redundant operators via equations-of-motion constraints is discussed in detail. Polarized cross sections for e{sup +}e{sup -}{yields}W{sup +}W{sup -} (on-shell) are computed and the corrections to the standard model results are given in an expansion for large s/M{sup 2}{sub W}. The dominant relative corrections grow with s and can be fully expressed in terms of modified gauge-fermion couplings. These corrections are interpreted in the context of the Goldstone boson equivalence theorem. Explicit new physics models are considered to illustrate the generation and the potential size of the coefficients in the effective Lagrangian. Brief comments are made on the production of W{sup +}W{sup -} pairs at the LHC.
8th International Workshop on Chiral Dynamics
2016-01-01
The International Workshop on Chiral Dynamics 2015, the eighth in a series which started in 1994 at MIT, and was later held in Mainz (1997), Jefferson Lab (2000 and 2012), Bonn (2003), Duke (2006) and Bern (2009), will take place in Pisa, from June 29 to July 3 2015, and will be jointly hosted by the Department of Physics of the University of Pisa and the Pisa branch of the Istituto Nazionale di Fisica Nucleare. The purpose of this workshop series is to bring physicists together who are active in this field, as well as those who are interested, to discuss and debate the most recent achievements and future developments. The workshop will have a near equal contribution from theorists and experimentalists and, as in the latest editions, a strong synergy with the lattice community will be present. Topics: Hadron structure Isospin breaking in hadronic systems Meson-meson and meson-baryon interaction Effective field theory and chiral perturbation theory Few-body physics Compton scattering and the polarizabilities o...
Energy Technology Data Exchange (ETDEWEB)
Floss, H.G. [Univ. of Washington, Seattle, WA (United States)
1994-12-01
This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.
Dual chiral density wave in quark matter
International Nuclear Information System (INIS)
Tatsumi, Toshitaka
2002-01-01
We prove that quark matter is unstable for forming a dual chiral density wave above a critical density, within the Nambu-Jona-Lasinio model. Presence of a dual chiral density wave leads to a uniform ferromagnetism in quark matter. A similarity with the spin density wave theory in electron gas and the pion condensation theory is also pointed out. (author)