Browsing by Subject "SYMMETRY"

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  • Zappa, Emilio; Dykeman, Eric C.; Geraets, James A.; Twarock, Reidun (2016)
    In this paper we describe a group theoretical approach to the study of structural transitions of icosahedral quasicrystals and point arrays. We apply the concept of Schur rotations, originally proposed by Kramer, to the case of aperiodic structures with icosahedral symmetry; these rotations induce a rotation of the physical and orthogonal spaces invariant under the icosahedral group, and hence, via the cut-and-project method, a continuous transformation of the corresponding model sets. We prove that this approach allows for a characterisation of such transitions in a purely group theoretical framework, and provide explicit computations and specific examples. Moreover, we prove that this approach can be used in the case of finite point sets with icosahedral symmetry, which have a wide range of applications in carbon chemistry (fullerenes) and biology (viral capsids).
  • Andersen, Jens O.; Brauner, Tomas; Hofmann, Christoph P.; Vuorinen, Aleksi (2014)
  • Baczyk, P.; Dobaczewski, J.; Konieczka, M.; Nakatsukasa, T.; Sato, K.; Satula, W. (2017)
    Isospin-symmetry-violating class II and III contact terms are introduced into the Skyrme energy density functional to account for charge dependence of the strong nuclear interaction. The two new coupling constants are adjusted to available experimental data on triplet and mirror displacement energies, respectively. We present preliminary results of the fit, focusing on its numerical stability with respect to the basis size.
  • Chatterjee, Arindam; Frank, Mariana; Fuks, Benjamin; Huitu, Katri; Mondal, Subhadeep; Rai, Santosh Kumar; Waltari, Harri (2019)
    We perform a comprehensive dark matter analysis of left-right supersymmetric scenarios that includes constraints from dark matter direct and indirect detection experiments and that presents distinctive features from those available in minimal supersymmetry. We concentrate on dark matter candidates which, while satisfying all constraints, are different from those of the minimal supersymmetric standard model. We consider in our analysis all possible co-annihilation channels relevant for setups in which several states are light and nearly degenerate, and devise a set of representative benchmark points, requiring co-annihilations, which satisfy all restrictions. We then study their consequent LHC signals, which exhibit promising new multileptonic signatures involving W-R, that if observed, would provide a strong support for left-right supersymmetry.
  • Frank, Mariana; Huitu, Katri; Maitra, Ushoshi; Patra, Monalisa (2016)
    We consider the Higgs-radion mixing in the context of warped space extradimensional models with custodial symmetry and investigate the prospects of detecting the mixed radion. Custodial symmetries allow the Kaluza-Klein excitations to be lighter and protect Zbb to be in agreement with experimental constraints. We perform a complementary study of discovery reaches of the Higgs-radion mixed state at the 13 and 14 TeV LHC and at the 500 and 1000 GeV International Linear Collider (ILC). We carry out a comprehensive analysis of the most significant production and decay modes of the mixed radion in the 80 GeV-1 TeV mass range and indicate the parameter space that can be probed at the LHC and the ILC. There exists a region of the parameter space which can be probed, at the LHC, through the diphoton channel even for a relatively low luminosity of 50 fb(-1). The reach of the four-lepton final state in probing the parameter space is also studied in the context of 14 TeV LHC, for a luminosity of 1000 fb(-1). At the ILC, with an integrated luminosity of 500 fb(-1), we analyze the Z-radion associated production and the WW fusion production, followed by the radion decay into b (b) over bar and W+W-. The WW fusion production is favored over the Z-radion associated channel in probing regions of the parameter space beyond the LHC reach. The complementary study at the LHC and the ILC is useful both for the discovery of the radion and the understanding of its mixing sector.
  • Tureanu, Anca (2018)
    We formulate the quantum field theory description of neutron-antineutron oscillations in the framework of canonical quantization, in analogy with the Bardeen-Cooper-Schrieffer theory and the Nambu-Jona-Lasinio model. The physical vacuum of the theory is a condensate of pairs of would-be neutrons and antineutrons in the absence of the baryon-number violating interaction. The quantization procedure defines uniquely the mixing of massive Bogoliubov quasiparticle states that represent the neutron. In spite of not being mass eigenstates, neutron and antineutron states are defined on the physical vacuum and the oscillation formulated in asymptotic states. The exchange of the baryonic number with the vacuum condensate engenders what may be observed as neutron-antineutron oscillation. The convergence between the present canonical approach and the Lagrangian/path integral approach to neutron oscillations is shown by the calculation of the anomalous (baryon-number violating) propagators. The quantization procedure proposed here can be extended to neutrino oscillations and, in general, to any particle oscillations.
  • The CMS collaboration; Sirunyan, A. M.; Eerola, P.; Kirschenmann, H.; Pekkanen, J.; Voutilainen, M.; Havukainen, J.; Heikkilä, J. K.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Laurila, S.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Siikonen, H.; Tuominen, E.; Tuominiemi, J.; Tuuva, T. (2019)
    A search has been performed for heavy resonances decaying to ZZ or ZW in 2l2q final states, with two charged leptons (l = e, mu) produced by the decay of a Z boson, and two quarks produced by the decay of a W or Z boson. The analysis is sensitive to resonances with masses in the range from 400 to 4500 GeV. Two categories are defined based on the merged or resolved reconstruction of the hadronically decaying vector boson, optimized for high- and low-mass resonances, respectively. The search is based on data collected during 2016 by the CMS experiment at the LHC in proton-proton collisions with a center-of-mass energy of root s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1). No excess is observed in the data above the standard model background expectation. Upper limits on the production cross section of heavy, narrow spin-1 and spin-2 resonances are derived as a function of the resonance mass, and exclusion limits on the production of W' bosons and bulk graviton particles are calculated in the framework of the heavy vector triplet model and warped extra dimensions, respectively.
  • Schunck, N.; Dobaczewski, J.; Satula, W.; Baczyk, P.; Dudek, J.; Gao, Y.; Konieczka, M.; Sato, K.; Shi, Y.; Wang, X. B.; Werner, T. R. (2017)
    We describe the new version (v2.73y) of the code hfodd which solves the nuclear Skyrme HartreeFock or Skyrme HartreeFockBogolyubov problem by using the Cartesian deformed harmonic-oscillator basis. In the new version, we have implemented the following new features: (i) full protonneutron mixing in the particlehole channel for Skyrme functionals, (ii) the Gogny force in both particlehole and particleparticle channels, (iii) linear multi-constraint method at finite temperature, (iv) fission toolkit including the constraint on the number of particles in the neck between two fragments, calculation of the interaction energy between fragments, and calculation of the nuclear and Coulomb energy of each fragment, (v) the new version 200d of the code hfbtho, together with an enhanced interface between hfbtho and hfodd, (vi) parallel capabilities, significantly extended by adding several restart options for large-scale jobs, (vii) the Lipkin translational energy correction method with pairing, (viii) higher-order Lipkin particle-number corrections, (ix) interface to a program plotting single-particle energies or Routhians, (x) strong-force isospin-symmetry-breaking terms, and (xi) the Augmented Lagrangian Method for calculations with 3D constraints on angular momentum and isospin. Finally, an important bug related to the calculation of the entropy at finite temperature and several other little significant errors of the previous published version were corrected. Program summary Title of the program:hfodd (v2.73y) Program Files doi:http://dx.doi.org/10.17632/3b28fs62wc.1 Licensing provisions: GPL v3 Programming language: FORTRAN-90 Journal reference of previous version: N. Schunck, J. Dobaczewski, J. McDonnell, W. Satula, J. Sheikh, A. Staszczak, M. Stoitsov, and P. Toivanen, Comput. Phys. Comm. 183 (2012) 166-192. Does the new version supersede the previous one: Yes Nature of problem: The nuclear mean field and an analysis of its symmetries in realistic cases are the main ingredients of a description of nuclear states. For the density functional generated by a zero-range velocity-dependent Skyrme interaction, the nuclear mean field is quasilocal. This allows for an effective and fast solution of the self-consistent HartreeFock equations, even for heavy nuclei, and for various nucleonic (n-particle n-hole) configurations, deformations, excitation energies, or angular momenta. Similarly, the local particleparticle density functional, generated by a zero-range interaction, allows for a simple implementation of pairing effects within the HartreeFockBogolyubov method. For finite-range interactions, like Coulomb, Yukawa, or Gogny interaction, the nuclear mean field becomes nonlocal, but using the spatial separability of the deformed harmonic-oscillator basis in three Cartesian directions, the self-consistent calculations can be efficiently performed. Solution method: The program uses the Cartesian harmonic oscillator basis to expand single-particle or single-quasiparticle wave functions of neutrons and protons interacting by means of the Skyrme or Gogny effective interactions and zero-range or finite-range pairing interactions. The expansion coefficients are determined by the iterative diagonalization of the mean-field Hamiltonians or Routhians which depend non-linearly on the local or nonlocal neutron, proton, or mixed protonneutron densities. Suitable constraints are used to obtain states corresponding to a given configuration, deformation or angular momentum. The method of solution has been presented in: J. Dobaczewski and J. Dudek, Comput. Phys. Comm. 102 (1997) 166. Summary of revisions: 1.Full proton-neutron mixing in the particlehole channel for Skyrme functionals was implemented. 2.The Gogny force was implemented in both particle-hole and particle-particle channels. 3.Linear multi-constraint method based on the cranking approximation of the QRPA matrix was extended at finite temperature. 4.Fission toolkit includes the constraint on the number of particles in the neck between two fragments, calculation of the interaction energy between fragments, and calculation of the nuclear and Coulomb energy of each fragment. 5.The HFBTHO module was updated to version 200d, and an enhanced interface between HFBTHO and HFODD was implemented. 6.Parallel capabilities were significantly extended by adding several restart options for large-scale jobs. 7.The Lipkin translational energy correction method with pairing was implemented. 8.Higher-order Lipkin particle-number corrections were implemented. 9.Interface to a program plotting single-particle energies or Routhians was added. 10.Strong-force isospin-symmetry-breaking terms were implemented. 11.The Augmented Lagrangian Method for calculations with 3D constraints on angular momentum and isospin was implemented. 12.An important bug related to the calculation of the entropy at finite temperature and several other little significant errors of the previous published version were corrected. Unusual features of the program: The user must have access to (i) the LAPACK subroutines zhpev, zhpevx, zheevr, or zheevd, which diagonalize complex hermitian matrices, (ii) the LAPACK subroutines dgetri and dgetrf which invert arbitrary real matrices, (iii) the LAPACK subroutines dsyevd, dsytrf and dsytri which compute eigenvalues and eigenfunctions of real symmetric matrices and (iv) the LINPACK subroutines zgedi and zgeco, which invert arbitrary complex matrices and calculate determinants, (v) the BLAS routines dcopy, dscal, dgeem and dgemv for double-precision linear algebra and zcopy, zdscal, zgeem and zgemv for complex linear algebra, or provide another set of subroutines that can perform such tasks. The BLAS and LAPACK subroutines can be obtained from the Netlib Repository at the University of Tennessee, Knoxville: http://netlib2.cs.utk.edu/. (C) 2017 Elsevier B.V. All rights reserved.
  • Bennett, Ed; Hong, Deog Ki; Lee, Jong-Wan; Lin, C.-J. David; Lucini, Biagio; Mesiti, Michele; Piai, Maurizio; Rantaharju, Jarno; Vadacchino, Davide (2020)
    We perform lattice studies of meson mass spectra and decay constants of the Sp(4) gauge theory in the quenched approximation. We consider two species of (Dirac) fermions as matter field content, transforming in the 2-index antisymmetric and the fundamental representation of the gauge group, respectively. All matter fields are formulated as Wilson fermions. We extrapolate to the continuum and massless limits and compare to each other the results obtained for the two species of mesons. In the case of two fundamental and three antisymmetric fermions, the long-distance dynamics is relevant for composite Higgs models. This is the first lattice study of this class of theories. The global SU(4)×SU(6) symmetry is broken to the Sp(4)×SO(6) subgroup, and the condensates align with the explicit mass terms present in the lattice formulation of the theory. The main results of our quenched calculations are that, with fermions in the 2-index antisymmetric representation of the group, the masses squared and decay constant squared of all the mesons we considered are larger than the corresponding quantities for the fundamental representation, by factors that vary between ∼1.2 and ∼2.7. We also present technical results that will be useful for future lattice investigations of dynamical simulations, of composite chimera baryons, and of the approach to large N in the Sp(2N) theories considered. We briefly discuss their high-temperature behavior, where symmetry restoration and enhancement are expected.
  • Zhao, Yafei; Broholm, Suvi K.; Wang, Feng; Rijpkema, Anneke S.; Lan, Tianying; Albert, Victor A.; Teeri, Teemu H.; Elomaa, Paula (2020)
    The large sunflower family, Asteraceae, is characterized by compressed, flower-like inflorescences that may bear phenotypically distinct flower types. The CYCLOIDEA (CYC)/TEOSINTE BRANCHED1-like transcription factors (TFs) belonging to the TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP) protein family are known to regulate bilateral symmetry in single flowers. In Asteraceae, they function at the inflorescence level, and were recruited to define differential flower type identities. Here, we identified upstream regulators of GhCYC3, a gene that specifies ray flower identity at the flower head margin in the model plant Gerbera hybrida. We discovered a previously unidentified expression domain and functional role for the paralogous CINCINNATA-like TCP proteins. They function upstream of GhCYC3 and affect the developmental delay of marginal ray primordia during their early ontogeny. At the level of single flowers, the Asteraceae CYC genes show a unique function in regulating the elongation of showy ventral ligules that play a major role in pollinator attraction. We discovered that during ligule development, the E class MADS-box TF GRCD5 activates GhCYC3 expression. We propose that the C class MADS-box TF GAGA1 contributes to stamen development upstream of GhCYC3. Our data demonstrate how interactions among and between the conserved floral regulators, TCP and MADS-box TFs, contribute to the evolution of the elaborate inflorescence architecture of Asteraceae.
  • Tiurev, Konstantin; Ollikainen, Tuomas; Kuopanportti, Pekko; Nakahara, Mikio; Hall, David S.; Möttönen, Mikko (2018)
    We introduce topologically stable three-dimensional skyrmions in the cyclic and biaxial nematic phases of a spin-2 Bose-Einstein condensate. These skyrmions exhibit exceptionally high mapping degrees resulting from the versatile symmetries of the corresponding order parameters. We show how these structures can be created in existing experimental setups and study their temporal evolution and lifetime by numerically solving the three-dimensional Gross-Pitaevskii equations for realistic parameter values. Although the biaxial nematic and cyclic phases are observed to be unstable against transition towards the ferromagnetic phase, their lifetimes are long enough for the skyrmions to be imprinted and detected experimentally.
  • Heikinheimo, Matti; Tenkanen, Tommi; Tuominen, Kimmo (2017)
    We study dark matter production in scenarios where a scale invariant hidden sector interacts with the Standard Model degrees of freedom via a Higgs portal. lambda Phi(dagger)Phi(2). If the hidden sector is very weakly coupled to the SM but exhibits strong interactions within its own particle species, the dark matter abundance may arise as a result of a dark freeze-out occurring in the hidden sector. Because of scale invariance, the free parameters in the hidden sector are determined, and the dark matter candidate exhibits a "WIMP miracle of the second kind." Demonstrating the predictive power of scale invariance, we carry out a thorough analysis of dark matter production in several benchmark scenarios where the hidden sector contains either a scalar, fermion (sterile neutrino), or vector dark matter and discuss the observational consequences of these scenarios.
  • Lehtinen, Valtteri; Pyötsiä, Krista; Snäll, Johanna; Toivari, Miika (2020)
    Purpose The human capability to detect the degree of zygomatico-orbital (ZMO) fracture dislocation in surgical treatment is unknown. The aim of the study was to examine the association between ZMO fracture dislocation and injury etiology and treatment. Methods The investigators implemented a retrospective cross-sectional study and enrolled a sample composed of patients with an isolated unilateral ZMO fracture and analyzed fracture dislocation from computed tomography (CT) images with an automatic algorithm. The primary predictor variable was mean surface point-to-point dislocation (the mean distance of dislocation for all surface points in isolated ZMO fracture segments between the original position and after virtual repositioning). The primary outcome was the treatment choice (operative versus nonoperative). Other studied variables were gender, age group, injury mechanism, clinical asymmetry, and human-evaluated dislocation in CT images. Descriptive and bivariate statistics were computed, and the threshold for statistical significance was set at P <.05. Results The sample consisted of 115 subjects with a mean age of 66.3 years, 66.1% of whom were male, and the most common cause of injury was falling on the ground (49.6%). Operative treatment was required for 58 (50.4%) subjects. There was a significant association between mean dislocation and operative treatment. The mean dislocation of operatively vs. nonoperatively treated fractures was 2.39 vs. 1.05 mm (P <.001). Mean fracture dislocation was greatest in injuries caused by assault (2.41 mm) and smallest in MVAs (1.08 mm) and ground-level falls (1.25 mm). The threshold of human eye detection for ZMO fracture dislocation was 1.97 mm. Conclusion The results of the present study demonstrate that the threshold for operative treatment of ZMO fracture dislocation is over 2 mm, which the human eye is able to detect. True dislocation is greater in younger than elderly patients and in injuries caused by assault compared to falling.