Phase transitions in the sdg interacting boson model
Van Isacker, P.; Bouldjedri, A.; Zerguine, S.
2010-05-01
A geometric analysis of the sdg interacting boson model is performed. A coherent state is used in terms of three types of deformation: axial quadrupole ( β), axial hexadecapole ( β) and triaxial ( γ). The phase-transitional structure is established for a schematic sdg Hamiltonian which is intermediate between four dynamical symmetries of U(15), namely the spherical U(5)⊗U(9), the (prolate and oblate) deformed SU(3) and the γ-soft SO(15) limits. For realistic choices of the Hamiltonian parameters the resulting phase diagram has properties close to what is obtained in the sd version of the model and, in particular, no transition towards a stable triaxial shape is found.
Phase transitions in the sdg interacting boson model
International Nuclear Information System (INIS)
Van Isacker, P.; Bouldjedri, A.; Zerguine, S.
2010-01-01
A geometric analysis of the sdg interacting boson model is performed. A coherent state is used in terms of three types of deformation: axial quadrupole (β 2 ), axial hexadecapole (β 4 ) and triaxial (γ 2 ). The phase-transitional structure is established for a schematic sdg Hamiltonian which is intermediate between four dynamical symmetries of U(15), namely the spherical U(5)xU(9), the (prolate and oblate) deformed SU ± (3) and the γ 2 -soft SO(15) limits. For realistic choices of the Hamiltonian parameters the resulting phase diagram has properties close to what is obtained in the sd version of the model and, in particular, no transition towards a stable triaxial shape is found.
Phase transitions in the sdg interacting boson model
Energy Technology Data Exchange (ETDEWEB)
Van Isacker, P. [Grand Accelerateur National d' Ions Lourds, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5 (France)], E-mail: isacker@ganil.fr; Bouldjedri, A.; Zerguine, S. [Department of Physics, PRIMALAB Laboratory, University of Batna, Avenue Boukhelouf M El Hadi, 05000 Batna (Algeria)
2010-05-15
A geometric analysis of the sdg interacting boson model is performed. A coherent state is used in terms of three types of deformation: axial quadrupole ({beta}{sub 2}), axial hexadecapole ({beta}{sub 4}) and triaxial ({gamma}{sub 2}). The phase-transitional structure is established for a schematic sdg Hamiltonian which is intermediate between four dynamical symmetries of U(15), namely the spherical U(5)xU(9), the (prolate and oblate) deformed SU{sub {+-}}(3) and the {gamma}{sub 2}-soft SO(15) limits. For realistic choices of the Hamiltonian parameters the resulting phase diagram has properties close to what is obtained in the sd version of the model and, in particular, no transition towards a stable triaxial shape is found.
Phases and phase transitions of S=1 bosons
Indian Academy of Sciences (India)
smukerjee
Quantum phases and phase transitions of bosons. Subroto Mukerjee. Dept. of Physics & Centre for Quantum. Information and Quantum Computing (CQIQC). Indian Institute of Science, Bangalore. 77th annual meeting of the IAS, Nov. 20 2011, PRL Ahmedabad ...
Proton-neutron sdg boson model and spherical-deformed phase transition
Otsuka, Takaharu; Sugita, Michiaki
1988-12-01
The spherical-deformed phase transition in nuclei is described in terms of the proton-neutron sdg interacting boson model. The sdg hamiltonian is introduced to model the pairing+quadrupole interaction. The phase transition is reproduced in this framework as a function of the boson number in the Sm isotopes, while all parameters in the hamiltonian are kept constant at values reasonable from the shell-model point of view. The sd IBM is derived from this model through the renormalization of g-boson effects.
Proton-neutron sdg boson model and spherical-deformed phase transition
Energy Technology Data Exchange (ETDEWEB)
Otsuka, Takaharu; Sugita, Michiaki
1988-12-15
The spherical-deformed phase transition in nuclei is described in terms of the proton-neutron sdg interacting boson model. The sdg hamiltonian is introduced to model the pairing + quadrupole interaction. The phase transition is reproduced in this framework as a function of the boson number in the Sm isotopes, while all parameters in the hamiltonian are kept constant at values reasonable from the shell-model point of view. The sd IBM is derived from this model through the renormalization of g-boson effects.
Proton-neutron sdg boson model and spherical-deformed phase transition
International Nuclear Information System (INIS)
Otsuka, Takaharu; Sugita, Michiaki
1988-01-01
The spherical-deformed phase transition in nuclei is described in terms of the proton-neutron sdg interacting boson model. The sdg hamiltonian is introduced to model the pairing + quadrupole interaction. The phase transition is reproduced in this framework as a function of the boson number in the Sm isotopes, while all parameters in the hamiltonian are kept constant at values reasonable from the shell-model point of view. The sd IBM is derived from this model through the renormalization of g-boson effects. (orig.)
Soft modes and structural phase transitions
Energy Technology Data Exchange (ETDEWEB)
Venkataraman, G [Reactor Research Centre, Kalpakkam (India)
1979-12-01
A survey of soft modes and their relationship to structural phase transitions is presented. After introducing the concept of a soft mode, the origin of softening is considered from a lattice-dynamical point. The Landau theory approach to structural transitions is then discussed, followed by a generalisation of the soft-mode concept through the use of the dynamic order-parameter susceptibility. The relationship of soft modes to broken symmetry is also examined. Experimental results for several classes of crystals are next presented, bringing out various features such as the co-operative Jahn-Teller effect. The survey concludes with a discussion of the central peak, touching upon both the experimental results and the theoretical speculations.
Phase transitions in the $sdg$ interacting boson model
Van Isacker, P.; Bouldjedri, A.; Zerguine, S.
2009-01-01
19 pages, 5 figures, submitted to Nuclear Physics A; A geometric analysis of the $sdg$ interacting boson model is performed. A coherent-state is used in terms of three types of deformation: axial quadrupole ($\\beta_2$), axial hexadecapole ($\\beta_4$) and triaxial ($\\gamma_2$). The phase-transitional structure is established for a schematic $sdg$ hamiltonian which is intermediate between four dynamical symmetries of U(15), namely the spherical ${\\rm U}(5)\\otimes{\\rm U}(9)$, the (prolate and ob...
Quantum Phase Transition in a Cold Atomic Spin-Boson Mixture
Orth, Peter P.; Stanic, Ivan; Le Hur, Karyn
2008-03-01
We theoretically implement a spin array in a tunable bosonic environment using cold bosonic atoms with two (hyperfine) ground states, trapped by different potentials [1]. The first specie lies in a deep optical lattice with tightly confining wells and forms a spin array; spin-up/down corresponds to occupation by one/no atom at each site. The second specie forms a superfluid reservoir. Different species are coupled coherently via laser transitions and collisions. Whereas the laser coupling mimics a transverse field for the spins, the coupling to the reservoir phonons (sound modes) induces a ferromagnetic (Ising) coupling as well as dissipation. This results in a peculiar ferro-paramagnetic quantum phase transition where the effect of dissipation can be studied in a controllable manner. [1] Peter P. Orth, Ivan Stanic, and Karyn Le Hur, arXiv:0711.2309 [cond-mat.other].
Boson localization and the superfluid-insulator transition
International Nuclear Information System (INIS)
Fisher, M.P.A.; Weichman, P.B.; Grinstein, G.; Fisher, D.S.; Condensed Matter Physics 114-36, California Institute of Technology, Pasadena, California 91125; IBM Research Division, Thomas J. Watson Research Center, Yorktown Heights, New York 10598; Joseph Henry Laboratory of Physics, Jadwin Hall, Princeton University, Princeton, New Jersey 08544)
1989-01-01
The phase diagrams and phase transitions of bosons with short-ranged repulsive interactions moving in periodic and/or random external potentials at zero temperature are investigated with emphasis on the superfluid-insulator transition induced by varying a parameter such as the density. Bosons in periodic potentials (e.g., on a lattice) at T=0 exhibit two types of phases: a superfluid phase and Mott insulating phases characterized by integer (or commensurate) boson densities, by the existence of a gap for particle-hole excitations, and by zero compressibility. Generically, the superfluid onset transition in d dimensions from a Mott insulator to superfluidity is ''ideal,'' or mean field in character, but at special multicritical points with particle-hole symmetry it is in the universality class of the (d+1)-dimensional XY model. In the presence of disorder, a third, ''Bose glass'' phase exists. This phase is insulating because of the localization effects of the randomness and analogous to the Fermi glass phase of interacting fermions in a strongly disordered potential
Majarshin, A. Jalili; Sabri, H.
2018-06-01
It is interesting that a change of nuclear shape may be described in terms of a phase transition. This paper studies the quantum phase transition of the U(5) to SO(6) in the interacting boson model (IBM) on the finite number N of bosons. This paper explores the well-known distinctive signatures of transition from spherical vibrational to γ-soft shape phase in the IBM with the variation of a control parameter. Quantum phase transitions occur as a result of properties of ground and excited states levels. We apply an affine \\widehat {SU(1,1)} approach to numerically solve non-linear Bethe Ansatz equation and point out what observables are particularly sensitive to the transition. The main aim of this work is to describe the most prominent observables of QPT by using IBM in shape coexistence configuration. We calculate energies of excited states and signatures of QPT as energy surface, energy ratio, energy differences, quadrupole electric transition rates and expectation values of boson number operators and show their behavior in QPT. These observables are calculated and examined for 98 - 102Mo isotopes.
Ghapanvari, M.; Ghorashi, A. H.; Ranjbar, Z.; Jafarizadeh, M. A.
2018-03-01
In this article, the negative-parity states in the odd-mass 103 - 109Rh isotopes in terms of the sd and sdg interacting-boson fermion models were studied. The transitional interacting boson-fermion model Hamiltonians in sd and sdg-IBFM versions based on affine SU (1 , 1) Lie Algebra were employed to describe the evolution from the spherical to deformed gamma unstable shapes along with the chain of Rh isotopes. In this method, sdg-IBFM Hamiltonian, which is a three level pairing Hamiltonian was determined easily via the exactly solvable method. Some observables of the shape phase transitions such as energy levels, the two neutron separation energies, signature splitting of the γ-vibrational band, the α-decay and double β--decay energies were calculated and examined for these isotopes. The present calculation correctly reproduces the spherical to gamma-soft phase transition in the Rh isotopes. Some comparisons were made with sd-IBFM.
Floquet engineering of Haldane Chern insulators and chiral bosonic phase transitions
Plekhanov, Kirill; Roux, Guillaume; Le Hur, Karyn
2017-01-01
The realization of synthetic gauge fields has attracted a lot of attention recently in relation to periodically driven systems and the Floquet theory. In ultracold atom systems in optical lattices and photonic networks, this allows one to simulate exotic phases of matter such as quantum Hall phases, anomalous quantum Hall phases, and analogs of topological insulators. In this paper, we apply the Floquet theory to engineer anisotropic Haldane models on the honeycomb lattice and two-leg ladder systems. We show that these anisotropic Haldane models still possess a topologically nontrivial band structure associated with chiral edge modes. Focusing on (interacting) boson systems in s -wave bands of the lattice, we show how to engineer through the Floquet theory, a quantum phase transition (QPT) between a uniform superfluid and a Bose-Einstein condensate analog of Fulde-Ferrell-Larkin-Ovchinnikov states, where bosons condense at nonzero wave vectors. We perform a Ginzburg-Landau analysis of the QPT on the graphene lattice, and compute observables such as chiral currents and the momentum distribution. The results are supported by exact diagonalization calculations and compared with those of the isotropic situation. The validity of high-frequency expansion in the Floquet theory is also tested using time-dependent simulations for various parameters of the model. Last, we show that the anisotropic choice for the effective vector potential allows a bosonization approach in equivalent ladder (strip) geometries.
Phase transitions and spin excitations of spin-1 bosons in optical lattice
Zhu, Min-Jie; Zhao, Bo
2018-03-01
For spin-1 bosonic system trapped in optical lattice, we investigate two main problems, including MI-SF phase transition and magnetic phase separations in MI phase, with extended standard basis operator (SBO) method. For both ferromagnetic (U2 0) systems, we analytically figure out the symmetry properties in Mott-insulator and superfluid phases, which would provide a deeper insight into the MI-SF phase transition process. Then by applying self-consistent approach to the method, we include the effect of quantum and thermal fluctuations and derive the MI-SF transition phase diagram, which is in quantitative agreement with recent Monte-Carlo simulation at zero temperature, and at finite temperature, we find the underestimation of finite-temperature-effect in the mean-field approximation method. If we further consider the spin excitations in the insulating states of spin-1 system in external field, distinct spin phases are expected. Therefore, in the Mott lobes with n = 1 and n = 2 atoms per site, we give analytical and numerical boundaries of the singlet, nematic, partially magnetic and ferromagnetic phases in the magnetic phase diagrams.
International Nuclear Information System (INIS)
Ye, Jinwu; Chen, Yan
2013-01-01
By using the dual vortex method (DVM), we develop systematically a simple and effective scheme to use the vortex degree of freedoms on dual lattices to characterize the symmetry breaking patterns of the boson insulating states in the direct lattices. Then we apply our scheme to study quantum phases and phase transitions in an extended boson Hubbard model slightly away from 1/3 (2/3) filling on frustrated lattices such as triangular and Kagome lattice. In a triangular lattice at 1/3, we find a X-CDW, a stripe CDW phase which was found previously by a density operator formalism (DOF). Most importantly, we also find a new CDW-VB phase which has both local CDW and local VB orders, in sharp contrast to a bubble CDW phase found previously by the DOF. In the Kagome lattice at 1/3, we find a VBS phase and a 6-fold CDW phase. Most importantly, we also identify a CDW-VB phase which has both local CDW and local VB orders which was found in previous QMC simulations. We also study several other phases which are not found by the DVM. By analyzing carefully the saddle point structures of the dual gauge fields in the translational symmetry breaking sides and pushing the effective actions slightly away from the commensurate filling f=1/3(2/3), we classified all the possible types of supersolids and analyze their stability conditions. In a triangular lattice, there are X-CDW supersolid, stripe CDW supersolid, but absence of any valence bond supersolid (VB-SS). There are also a new kind of supersolid: CDW-VB supersolid. In a Kagome lattice, there are 6-fold CDW supersolid, stripe CDW supersolid, but absence of any valence bond supersolid (VB-SS). There are also a new kind of supersolid: CDW-VB supersolid. We show that independent of the types of the SS, the quantum phase transitions from solids to supersolids driven by a chemical potential are in the same universality class as that from a Mott insulator to a superfluid, therefore have exact exponents z=2, ν=1/2, η=0 (with
Directory of Open Access Journals (Sweden)
J.E. García-Ramos
2014-09-01
Full Text Available We introduce the basic concepts of catastrophe theory needed to derive analytically the phase diagram of the proton–neutron interacting boson model (IBM-2. Previous studies [1–3] were based on numerical solutions. We here explain the whole IBM-2 phase diagram including the precise order of the phase transitions in terms of the cusp catastrophe.
On the calculation of soft phase space integral
International Nuclear Information System (INIS)
Zhu, Hua Xing
2015-01-01
The recent discovery of the Higgs boson at the LHC attracts much attention to the precise calculation of its production cross section in quantum chromodynamics. In this work, we discuss the calculation of soft triple-emission phase space integral, which is an essential ingredient in the recently calculated soft-virtual corrections to Higgs boson production at next-to-next-to-next-to-leading order. The main techniques used this calculation are method of differential equation for Feynman integral, and integration of harmonic polylogarithms.
From bosonic topological transition to symmetric fermion mass generation
You, Yi-Zhuang; He, Yin-Chen; Vishwanath, Ashvin; Xu, Cenke
2018-03-01
A bosonic topological transition (BTT) is a quantum critical point between the bosonic symmetry-protected topological phase and the trivial phase. In this work, we investigate such a transition in a (2+1)-dimensional lattice model with the maximal microscopic symmetry: an internal SO (4 ) symmetry. We derive a description for this transition in terms of compact quantum electrodynamics (QED) with four fermion flavors (Nf=4 ). Within a systematic renormalization group analysis, we identify the critical point with the desired O (4 ) emergent symmetry and all expected deformations. By lowering the microscopic symmetry, we recover the previous Nf=2 noncompact QED description of the BTT. Finally, by merging two BTTs we recover a previously discussed theory of symmetric mass generation, as an SU (2 ) quantum chromodynamics-Higgs theory with Nf=4 flavors of SU (2 ) fundamental fermions and one SU (2 ) fundamental Higgs boson. This provides a consistency check on both theories.
Microscopic mean-field boson approach to the shape transition in Sm isotopes
International Nuclear Information System (INIS)
Kuchta, R.
1988-01-01
The phase transition from spherical to deformed shape in Sm 146-156 nuclei is analyzed within the mean-field approximation applied to the Dyson image of the shell-model Hamiltonian. No quasiparticle transformation is involved in the present approach and the Pauli principle in the physical boson subspace is properly taken into account. The low-lying spectra, B(E2; O 1 + →2 + ) probabilities and the corresponding densities of electromagnetic transitions are calculated. The results provide a reasonable explanation of the phase transition in the Sm isotopes. The role of bosons with different multipolarity is investigated and it is found that g-bosons (J=4) cannot be neglected in the transition region. Comparison of the present results with those of other approaches is given as well
Soft x-ray induced femtosecond solid-to-solid phase transition
Czech Academy of Sciences Publication Activity Database
Tavella, F.; Höppner, H.; Tkachenko, V.; Medvedev, Nikita; Capotondi, F.; Golz, T.; Kai, Y.; Manfredda, M.; Pedersoli, E.; Prandolini, M.J.; Stojanovic, N.; Tanikawa, T.; Teubner, U.; Toleikis, S.; Ziaja, B.
Roč. 24, Sep (2017), s. 22-27 ISSN 1574-1818 Institutional support: RVO:68378271 Keywords : soft x-ray * ultrashort x-ray pulses * grafitization of diamond * non-thermal phase transition Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 0.908, year: 2016
Chiral phase transition in the soft-wall model of AdS/QCD
International Nuclear Information System (INIS)
Chelabi, Kaddour; Fang, Zhen; Huang, Mei; Li, Danning; Wu, Yue-Liang
2016-01-01
We investigate the chiral phase transition in the soft-wall model of AdS/QCD at zero chemical potential for two-flavor and three-flavor cases, respectively. We show that there is no spontaneous chiral symmetry breaking in the original soft-wall model. After detailed analysis, we find that in order to realize chiral symmetry breaking and restoration, both profiles for the scalar potential and the dilaton field are essential. The scalar potential determines the possible solution structure of the chiral condensate, except the mass term, it takes another quartic term for the two-flavor case, and for the three-flavor case, one has to take into account an extra cubic term due to the t’Hooft determinant interaction. The profile of the dilaton field reflects the gluodynamics, which is negative at a certain ultraviolet scale and approaches positive quadratic behavior at far infrared region. With this set-up, the spontaneous chiral symmetry breaking in the vacuum and its restoration at finite temperature can be realized perfectly. In the two-flavor case, it gives a second order chiral phase transition in the chiral limit, while the transition turns to be a crossover for any finite quark mass. In the case of three-flavor, the phase transition becomes a first order one in the chiral limit, while above sufficient large quark mass it turns to be a crossover again. This scenario agrees exactly with the current understanding on chiral phase transition from lattice QCD and other effective model studies.
Mitra, Aditi
2012-12-28
A renormalization group approach is used to show that a one-dimensional system of bosons subject to a lattice quench exhibits a finite-time dynamical phase transition where an order parameter within a light cone increases as a nonanalytic function of time after a critical time. Such a transition is also found for a simultaneous lattice and interaction quench where the effective scaling dimension of the lattice becomes time dependent, crucially affecting the time evolution of the system. Explicit results are presented for the time evolution of the boson interaction parameter and the order parameter for the dynamical transition as well as for more general quenches.
Phase diagram of a bosonic ladder with two coupled chains
International Nuclear Information System (INIS)
Luthra, Meetu Sethi; Mishra, Tapan; Pai, Ramesh V.; Das, B. P.
2008-01-01
We study a bosonic ladder with two coupled chains using the finite-size density-matrix renormalization group method. We show that in a commensurate bosonic ladder the critical on-site interaction (U C ) for the superfluid to Mott insulator transition gets larger as the interchain hopping (t perpendicular ) increases. We analyze this quantum phase transition and obtain the phase diagram in the t perpendicular -U plane. We also consider the asymmetric case where the on-site interactions are different in the two chains and have shown that the system as a whole will not be in the Mott insulator phase unless both the chains have on-site interactions greater than the critical value
International Nuclear Information System (INIS)
Anderson, G.W.
1991-01-01
An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, left-angle φ right-angle T is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of left-angle φ right-angle T . In very minimal extensions of the standard model it is quite easy to increase left-angle φ right-angle T so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value left-angle φ right-angle = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state left-angle φ right-angle = 246 GeV unstable. The requirement that the state left-angle φ right-angle = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field
International Nuclear Information System (INIS)
Fuhrer, Andreas; Manohar, Aneesh V.; Waalewijn, Wouter J.
2011-01-01
Soft-collinear effective theory (SCET) is applied to compute electroweak radiative corrections to Higgs production via gauge boson fusion, qq→qqH. There are several novel features which make this process an interesting application of SCET: The amplitude is proportional to the Higgs vacuum expectation value, and so is not a gauge singlet amplitude. Standard resummation methods require a gauge singlet operator and do not apply here. The SCET analysis requires operators with both collinear and soft external fields, with the Higgs vacuum expectation value being described by an external soft φ field. There is a scalar soft-collinear transition operator in the SCET Lagrangian which contributes to the scattering amplitude, and is derived here.
Energy Technology Data Exchange (ETDEWEB)
Bulava, John; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Gerhold, Philip; Kallarackal, Jim; Nagy, Attila [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humbolt-Univ. Berlin (Germany)
2011-12-15
We study a chirally invariant Higgs-Yukawa model regulated on a space-time lattice. We calculate Higgs boson resonance parameters and mass bounds for various values of the mass of the degenerate fermion doublet. Also, first results on the phase transition temperature are presented. In general, this model may be relevant for BSM scenarios with a heavy fourth generation of quarks. (orig.)
Phase structure and phase transition of the SU(2) Higgs model in three dimensions
International Nuclear Information System (INIS)
Buchmueller, W.; Philipsen, O.
1994-11-01
We derive a set of gauge independent gap equations for Higgs boson and vector boson masses for the SU(2) Higgs model in three dimensions. The solutions can be associated with the Higgs phase and the symmetric phase, respectively. In the Higgs phase the calculated masses are in agreement with results from perturbation theory. In the symmetric phase a non-perturbative vector boson mass is generated by the non-abelian gauge interactions, whose value is rather independent of the scalar self-coupling λ. For small values of λ the phase transition is first-order. Its strength decreases with increasing λ, and at a critical value λ c the first-order transition changes to a crossover. Based on a perturbative matching the three-dimensional theory is related to the four-dimensional theory at high temperatures. The critical Higgs mass m H c , corresponding to the critical coupling λ c , is estimated to be below 100 GeV. The ''symmetric phase'' of the theory can be interpreted as a Higgs phase whose parameters are determined non-perturbatively. The obtained Higgs boson and vector boson masses are compared with recent results from lattice Monte Carlo simulations. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Hashino, Katsuya, E-mail: hashino@jodo.sci.u-toyama.ac.jp [Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Kakizaki, Mitsuru, E-mail: kakizaki@sci.u-toyama.ac.jp [Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Kanemura, Shinya, E-mail: kanemu@sci.u-toyama.ac.jp [Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Ko, Pyungwon, E-mail: pko@kias.re.kr [School of Physics, KIAS, Seoul 02455 (Korea, Republic of); Matsui, Toshinori, E-mail: matsui@kias.re.kr [School of Physics, KIAS, Seoul 02455 (Korea, Republic of)
2017-03-10
We calculate the spectrum of gravitational waves originated from strongly first order electroweak phase transition in the extended Higgs model with a real singlet scalar field. In order to calculate the bubble nucleation rate, we perform a two-field analysis and evaluate bounce solutions connecting the true and the false vacua using the one-loop effective potential at finite temperatures. Imposing the Sakharov condition of the departure from thermal equilibrium for baryogenesis, we survey allowed regions of parameters of the model. We then investigate the gravitational waves produced at electroweak bubble collisions in the early Universe, such as the sound wave, the bubble wall collision and the plasma turbulence. We find that the strength at the peak frequency can be large enough to be detected at future space-based gravitational interferometers such as eLISA, DECIGO and BBO. Predicted deviations in the various Higgs boson couplings are also evaluated at the zero temperature, and are shown to be large enough too. Therefore, in this model strongly first order electroweak phase transition can be tested by the combination of the precision study of various Higgs boson couplings at the LHC, the measurement of the triple Higgs boson coupling at future lepton colliders and the shape of the spectrum of gravitational wave detectable at future gravitational interferometers.
Glass transition in soft-sphere dispersions
International Nuclear Information System (INIS)
RamIrez-Gonzalez, P E; Medina-Noyola, M
2009-01-01
The concept of dynamic equivalence among mono-disperse soft-sphere fluids is employed in the framework of the self-consistent generalized Langevin equation (SCGLE) theory of colloid dynamics to calculate the ideal glass transition phase diagram of model soft-sphere colloidal dispersions in the softness-concentration state space. The slow dynamics predicted by this theory near the glass transition is compared with available experimental data for the decay of the intermediate scattering function of colloidal dispersions of soft-microgel particles. Increasing deviations from this simple scheme occur for increasingly softer potentials, and this is studied here using the Rogers-Young static structure factor of the soft-sphere systems as the input of the SCGLE theory, without assuming a priori the validity of the equivalence principle above.
Probing the electroweak phase transition via enhanced di-Higgs boson production
Carena, Marcela; Liu, Zhen; Riembau, Marc
2018-05-01
We consider a singlet extension of the standard model (SM) with a spontaneous Z2 breaking and study the gluon-gluon fusion production of the heavy scalar, with subsequent decay into a pair of SM-like Higgs bosons. We find that an on-shell interference effect can notably enhance the resonant di-Higgs production rate up to 40%. In addition, consistently taking into account both the on-shell and off-shell interference effects between the heavy scalar and the SM di-Higgs diagrams significantly improves the HL-LHC and HE-LHC reach in this channel. As an example, within an effective field theory analysis in an explicitly Z2 breaking scenario, we further discuss the potential to probe the parameter region compatible with a first-order electroweak phase transition. Our analysis is applicable for general potentials of the singlet extension of the SM as well as for more general resonance searches.
Goldstone bosons in a crystalline chiral phase
International Nuclear Information System (INIS)
Schramm, Marco
2017-01-01
The phase diagram of strong interaction matter is expected to exhibit a rich structure. Different models have shown, that crystalline phases with a spatially varying chiral condensate can occur in the regime of low temperatures and moderate densities, where they replace the first-order phase transition found for spatially constant order parameters. We investigate this inhomogeneous phase, where in addition to the chiral symmetry, translational and rotational symmetry are broken as well, in a two flavor Nambu--Jona-Lasinio model. The main goal of this work is to describe the Goldstone bosons in this phase, massless excitations that occur for spontaneously broken symmetries. We take one of the simplest possible modulations, the chiral density wave, and show how to derive the quark propagator of the theory analytically, by means of transformations in chiral and momentum space. We apply this to a test case for the gap equation. We show the derivation of Nambu-Goldstone modes in the inhomogeneous phase and find, that for our case only three different modes have to be taken into account. We proceed to calculate the Goldstone boson related to the breaking of spatial symmetry, which can be related to the neutral pion. By evaluating a Bethe-Salpeter equation, we can show, that we have indeed found a Goldstone boson and give its dispersion relation in terms of momenta perpendicular, as well as parallel to the mass modulation.
Goldstone bosons in a crystalline chiral phase
Energy Technology Data Exchange (ETDEWEB)
Schramm, Marco
2017-07-24
The phase diagram of strong interaction matter is expected to exhibit a rich structure. Different models have shown, that crystalline phases with a spatially varying chiral condensate can occur in the regime of low temperatures and moderate densities, where they replace the first-order phase transition found for spatially constant order parameters. We investigate this inhomogeneous phase, where in addition to the chiral symmetry, translational and rotational symmetry are broken as well, in a two flavor Nambu--Jona-Lasinio model. The main goal of this work is to describe the Goldstone bosons in this phase, massless excitations that occur for spontaneously broken symmetries. We take one of the simplest possible modulations, the chiral density wave, and show how to derive the quark propagator of the theory analytically, by means of transformations in chiral and momentum space. We apply this to a test case for the gap equation. We show the derivation of Nambu-Goldstone modes in the inhomogeneous phase and find, that for our case only three different modes have to be taken into account. We proceed to calculate the Goldstone boson related to the breaking of spatial symmetry, which can be related to the neutral pion. By evaluating a Bethe-Salpeter equation, we can show, that we have indeed found a Goldstone boson and give its dispersion relation in terms of momenta perpendicular, as well as parallel to the mass modulation.
Directory of Open Access Journals (Sweden)
Katsuya Hashino
2017-03-01
Full Text Available We calculate the spectrum of gravitational waves originated from strongly first order electroweak phase transition in the extended Higgs model with a real singlet scalar field. In order to calculate the bubble nucleation rate, we perform a two-field analysis and evaluate bounce solutions connecting the true and the false vacua using the one-loop effective potential at finite temperatures. Imposing the Sakharov condition of the departure from thermal equilibrium for baryogenesis, we survey allowed regions of parameters of the model. We then investigate the gravitational waves produced at electroweak bubble collisions in the early Universe, such as the sound wave, the bubble wall collision and the plasma turbulence. We find that the strength at the peak frequency can be large enough to be detected at future space-based gravitational interferometers such as eLISA, DECIGO and BBO. Predicted deviations in the various Higgs boson couplings are also evaluated at the zero temperature, and are shown to be large enough too. Therefore, in this model strongly first order electroweak phase transition can be tested by the combination of the precision study of various Higgs boson couplings at the LHC, the measurement of the triple Higgs boson coupling at future lepton colliders and the shape of the spectrum of gravitational wave detectable at future gravitational interferometers.
Phase diagram of two-component bosons on an optical lattice
International Nuclear Information System (INIS)
Altman, Ehud; Hofstetter, Walter; Demler, Eugene; Lukin, Mikhail D
2003-01-01
We present a theoretical analysis of the phase diagram of two-component bosons on an optical lattice. A new formalism is developed which treats the effective spin interactions in the Mott and superfluid phases on the same footing. Using this new approach we chart the phase boundaries of the broken spin symmetry states up to the Mott to superfluid transition and beyond. Near the transition point, the magnitude of spin exchange can be very large, which facilitates the experimental realization of spin-ordered states. We find that spin and quantum fluctuations have a dramatic effect on the transition, making it first order in extended regions of the phase diagram. When each species is at integer filling, an additional phase transition may occur, from a spin-ordered insulator to a Mott insulator with no broken symmetries. We determine the phase boundaries in this regime and show that this is essentially a Mott transition in the spin sector
Ra isotopes in the sdg interacting-boson model with one f-boson
Energy Technology Data Exchange (ETDEWEB)
Yoshinaga, Naotaka (Department of Physics, Saitama University (Japan)); Mizusaki, Takahiro (Department of Physics, University of Tokyo (Japan)); Otsuka, Takaharu (Department of Physics, University of Tokyo (Japan))
1993-06-21
We study positive- and negative-parity states in Ra isotopes in terms of the proton-neutron sdg interacting-boson model with one f-boson. The present calculation correctly reproduces the spherical to deformed phase transition. Especially, we would like to stress the importance of the g-boson for reproducing the E1 transitions which are very strong in this region. (orig.)
Ra isotopes in the sdg interacting-boson model with one f-boson
Naotaka, Yoshinaga; Takahiro, Mizusaki; Takaharu, Otsuka
1993-06-01
We study positive- and negative-parity states in Ra isotopes in terms of the proton-neutron sdg interacting-boson model with one f-boson. The present calculation correctly reproduces the spherical to deformed phase transition. Especially, we would like to stress the importance of the g-boson for reproducing the E1 transitions which are very strong in this region.
Ra isotopes in the sdg interacting-boson model with one f-boson
International Nuclear Information System (INIS)
Yoshinaga, Naotaka; Mizusaki, Takahiro; Otsuka, Takaharu.
1992-01-01
We study positive and negative parity in Ra isotopes in terms of the proton-neutron sdg interacting-boson model with one f-boson. The present calculation correctly reproduces the spherical to deformed phase transition. Especially, we would like to stress the importance of the g-boson for reproducing the E1 transitions which are very strong in this region. (author)
A first order phase transition from inflationary to big bang universe
International Nuclear Information System (INIS)
Horwitz, G.
1986-01-01
The microcanonical entropy is calculated for a system of massive, conformally coupled, scalar bosons using a conformal gravitational theory. The resulting entropy is seen to indicate a first order phase transition from an inflationary expansion stage (where the amplitude of the scalar boson follows that of the scale function of the universe and the mass of the solar boson is the source of the cosmological constant) to a big bang stage (where neither of these conditions hold). Such a first order phase transition involves an entropy increase of some thirty orders of magnitude. In the author's theory, the invariant temperature (proper temperature times scale function) is not zero, nor is it the Hawking temperature, but it is tens of magnitudes smaller than the corresponding temperature of the big bang stage. A specific model for these bosons that provides the phase transition and serves as the source of the cosmological constant is also examined briefly, where the bosons are identified as spontaneously generated primordial black holes as in the cosmological model of Brout, Englert and Casher. In that case, the decay of the black holes provides a decaying cosmological constant and an explicit mechanism for heating up the universe
Comments on the electroweak phase transition
International Nuclear Information System (INIS)
Dine, M.; Leigh, R.G.; Huet, P.; Linde, A.; Linde, D.
1992-01-01
We report on an investigation of various problems related to the theory of the electroweak phase transition. This includes a determination of the nature of the phase transition, a discussion of the possible role of higher order radiative corrections and the theory of the formation and evolution of the bubbles of the new phase. We find in particular that no dangerous linear terms appear in the effective potential. However, the strength of the first-order phase transition is 2/3 times less than what follows from the one-loop approximation. This rules out baryogenesis in the minimal version of the electroweak theory with light Higgs bosons. (orig.)
Simulating the electroweak phase transition in the SU(2) Higgs model
International Nuclear Information System (INIS)
Fodor, Z.; Hein, J.; Jansen, K.; Jaster, A.; Montvay, I.
1994-09-01
Numerical simulations are performed to study the finite temperature phase transition in the SU(2) Higgs model on the lattice. In the presently investigated range of the Higgs boson mass, below 50 GeV, the phase transition turns out to be of first order and its strength is rapidly decreasing with increasing Higgs boson mass. In order to control the systematic errors, we also perform studies of scaling violations and of finite volume effects. (orig.)
Subsubleading soft theorems of gravitons and dilatons in the bosonic string
International Nuclear Information System (INIS)
Vecchia, Paolo Di; Marotta, Raffaele; Mojaza, Matin
2016-01-01
Starting from the amplitude with an arbitrary number of massless closed states of the bosonic string, we compute the soft limit when one of the states becomes soft to subsubleading order in the soft momentum expansion, and we show that when the soft state is a graviton or a dilaton, the full string amplitude can be expressed as a soft theorem through subsubleading order. It turns out that there are string corrections to the field theoretical limit in the case of a soft graviton, while for a soft dilaton the string corrections vanish. We then show that the new soft theorems, including the string corrections, can be simply obtained from the exchange diagrams where the soft state is attached to the other external states through the three-point string vertex of three massless states. In the soft-limit, the propagator of the exchanged state is divergent, and at tree-level these are the only divergent contributions to the full amplitude. However, they do not form a gauge invariant subset and must be supplemented with extra non-singular terms. The requirement of gauge invariance then fixes the complete amplitude through subsubleading order in the soft expansion, reproducing exactly what one gets from the explicit calculation in string theory. From this it is seen that the string corrections at subsubleading order arise as a consequence of the three-point amplitude having string corrections in the bosonic string. When specialized to a soft dilaton, it remarkably turns out that the string corrections vanish and that the non-singular piece of the subsubleading term of the dilaton soft theorem is the generator of space-time special conformal transformation.
The Quantum Space Phase Transitions for Particles and Force Fields
Directory of Open Access Journals (Sweden)
Chung D.-Y.
2006-07-01
Full Text Available We introduce a phenomenological formalism in which the space structure is treated in terms of attachment space and detachment space. Attachment space attaches to an object, while detachment space detaches from the object. The combination of these spaces results in three quantum space phases: binary partition space, miscible space and binary lattice space. Binary lattice space consists of repetitive units of alternative attachment space and detachment space. In miscible space, attachment space is miscible to detachment space, and there is no separation between attachment space and detachment spaces. In binary partition space, detachment space and attachment space are in two separat continuous regions. The transition from wavefunction to the collapse of wavefuction under interference becomes the quantum space phase transition from binary lattice space to miscible space. At extremely conditions, the gauge boson force field undergoes a quantum space phase transition to a "hedge boson force field", consisting of a "vacuum" core surrounded by a hedge boson shell, like a bubble with boundary.
Charge and transition densities of samarium isotopes in the interacting Boson model
International Nuclear Information System (INIS)
Moinester, M.A.; Alster, J.; Dieperink, A.E.L.
1982-01-01
The interacting boson approximation (IBA) model has been used to interpret the ground-state charge distributions and lowest 2 + transition charge densities of the even samarium isotopes for A = 144-154. Phenomenological boson transition densities associated with the nucleons comprising the s-and d-bosons of the IBA were determined via a least squares fit analysis of charge and transition densities in the Sm isotopes. The application of these boson trasition densities to higher excited 0 + and 2 + states of Sm, and to 0 + and 2 + transitions in neighboring nuclei, such as Nd and Gd, is described. IBA predictions for the transition densities of the three lowest 2 + levels of 154 Gd are given and compared to theoretical transition densities based on Hartree-Fock calculations. The deduced quadrupole boson transition densities are in fair agreement with densities derived previously from 150 Nd data. It is also shown how certain moments of the best fit boson transition densities can simply and sucessfully describe rms radii, isomer shifts, B(E2) strengths, and transition radii for the Sm isotopes. (orig.)
Bosonic Confinement and Coherence in Disordered Nanodiamond Arrays.
Zhang, Gufei; Samuely, Tomas; Du, Hongchu; Xu, Zheng; Liu, Liwang; Onufriienko, Oleksandr; May, Paul W; Vanacken, Johan; Szabó, Pavol; Kačmarčík, Jozef; Yuan, Haifeng; Samuely, Peter; Dunin-Borkowski, Rafal E; Hofkens, Johan; Moshchalkov, Victor V
2017-11-28
In the presence of disorder, superconductivity exhibits short-range characteristics linked to localized Cooper pairs which are responsible for anomalous phase transitions and the emergence of quantum states such as the bosonic insulating state. Complementary to well-studied homogeneously disordered superconductors, superconductor-normal hybrid arrays provide tunable realizations of the degree of granular disorder for studying anomalous quantum phase transitions. Here, we investigate the superconductor-bosonic dirty metal transition in disordered nanodiamond arrays as a function of the dispersion of intergrain spacing, which ranges from angstroms to micrometers. By monitoring the evolved superconducting gaps and diminished coherence peaks in the single-quasiparticle density of states, we link the destruction of the superconducting state and the emergence of bosonic dirty metallic state to breaking of the global phase coherence and persistence of the localized Cooper pairs. The observed resistive bosonic phase transitions are well modeled using a series-parallel circuit in the framework of bosonic confinement and coherence.
Boson forbidden transitions and their manifestation in spherical nuclei
International Nuclear Information System (INIS)
Stoyanov, Ch.
2002-01-01
For the correct description of the 'boson forbidden' transitions it is necessary to go beyond the quasi-boson approximation and to take into account the fermion structure of the phonons. Once it done it is quantitative description of the transitions is possible within the simplest model based on the separable residual interactions. Calculations of the forbidden E1-transitions in 120 Sn, 144 Sm and 144 Nd are presented. Analysis of some low-energy M1-transitions is made using IBM-2. The discussed examples reveal the complex properties of the low-lying excited states
Towards the theory of the electroweak phase transition
International Nuclear Information System (INIS)
Dine, M.; Leigh, R.G.; Huet, P.; Linde, A.; Linde, D.
1992-01-01
We investigate various problems related to the theory of the electroweak phase transition. This includes determination of the nature of the phase transition, discussion of the possible role of the higher-order radiative corrections, and the theory of the formation and evolution of bubbles of the new phase. We show, in particular, that no dangerous linear terms in the scalar field φ appear in the expression for the effective potential. We have found that, for the Higgs-boson mass smaller than the masses of W and Z bosons, the phase transition is of the first order. However, its strength is approximately 2/3 times less than what follows from the one-loop approximation. The phase transition occurs due to production and expansion of critical bubbles. Subcritical bubbles may be important only if the phase transition is very weakly first order. A general analytic expression for the probability of the bubble formation is obtained, which may be used for study of tunneling in a wide class of theories. The bubble-wall velocity depends on many factors, including the ratio of the mean free path of the particles to the thickness of the wall. Thin walls in the electroweak theory have a nonrelativistic velocity, whereas thick walls may be relativistic. A decrease of the cubic term by the factor 2/3 rules our baryogenesis in the minimal version of the electroweak theory. Even though we concentrate in this paper on the phase transition in this theory, most of our results can be applied to more general models as well, where baryogenesis is possible
Status of electroweak phase transition and baryogenesis
Indian Academy of Sciences (India)
It is possible that the universe has undergone a number of phase transitions, as illustrated in table 1. .... А, and perturbation theory breaks down for heavy Higgs bosons, ..... This is good news, since the neutron and electric dipole moment.
Massive Boson Production at Small qT in Soft-Collinear Effective Theory
Becher, Thomas; Neubert, Matthias; Wilhelm, Daniel
2013-01-01
We study the differential cross sections for electroweak gauge-boson and Higgs production at small and very small transverse-momentum qT. Large logarithms are resummed using soft-collinear effective theory. The collinear anomaly generates a non-perturbative scale q*, which protects the processes from receiving large long-distance hadronic contributions. A numerical comparison of our predictions with data on the transverse-momentum distribution in Z-boson production at the Tevatron and LHC is given.
Symmetry and Phase Transitions in Nuclei
International Nuclear Information System (INIS)
Iachello, F.
2009-01-01
Phase transitions in nuclei have received considerable attention in recent years, especially after the discovery that, contrary to expectations, systems at the critical point of a phase transition display a simple structure. In this talk, quantum phase transitions (QPT), i.e. phase transitions that occur as a function of a coupling constant that appears in the quantum Hamiltonian, H, describing the system, will be reviewed and experimental evidence for their occurrence in nuclei will be presented. The phase transitions discussed in the talk will be shape phase transitions. Different shapes have different symmetries, classified by the dynamic symmetries of the Interacting Boson Model, U(5), SU(3) and SO(6). Very recently, the concept of Quantum Phase Transitions has been extended to Excited State Quantum Phase Transitions (ESQPT). This extension will be discussed and some evidence for incipient ESQPT in nuclei will be presented. Systems at the critical point of a phase transition are called 'critical systems'. Approximate analytic formulas for energy spectra and other properties of 'critical nuclei', in particular for nuclei at the critical point of the second order U(5)-SO(6) transition, called E(5), and along the line of first order U(5)-SU(3) transitions, called X(5), will be presented. Experimental evidence for 'critical nuclei' will be also shown. Finally, the microscopic derivation of shape phase transitions in nuclei within the framework of density functional methods will be briefly discussed.(author)
International Nuclear Information System (INIS)
Zastavenko, L.G.
1979-01-01
The usual proof of the phase transition existence in the gphi 4 model is considered. (For M 2 >M 0 2 minimum of the effective potential is at phi(0)=0, for M 2 >M 0 2 this minimum is at phi(0)=+-lambda not equal to 0, lambda→+ infinity at M 2 →- infinity). This proof is shown to be wrong, thus suggesting the absence in the model considered of the phase transition, vacuum degeneration, spontaneous symmetry breaking and zero-mass Goldstone-bosons
Experimental signatures of a nonequilibrium phase transition governing the yielding of a soft glass.
Hima Nagamanasa, K; Gokhale, Shreyas; Sood, A K; Ganapathy, Rajesh
2014-06-01
We present direct experimental signatures of a nonequilibrium phase transition associated with the yield point of a prototypical soft solid-a binary colloidal glass. By simultaneously quantifying single-particle dynamics and bulk mechanical response, we identified the threshold for the onset of irreversibility with the yield strain. We extracted the relaxation time from the transient behavior of the loss modulus and found that it diverges in the vicinity of the yield strain. This critical slowing down is accompanied by a growing correlation length associated with the size of regions of high Debye-Waller factor, which are precursors to yield events in glasses. Our results affirm that the paradigm of nonequilibrium critical phenomena is instrumental in achieving a holistic understanding of yielding in soft solids.
Singlet Higgs phenomenology and the electroweak phase transition
International Nuclear Information System (INIS)
Profumo, Stefano; Ramsey-Musolf, Michael J.; Shaughnessy, Gabe
2007-01-01
We study the phenomenology of gauge singlet extensions of the Standard Model scalar sector and their implications for the electroweak phase transition. We determine the conditions on the scalar potential parameters that lead to a strong first order phase transition as needed to produce the observed baryon asymmetry of the universe. We analyze the constraints on the potential parameters derived from Higgs boson searches at LEP and electroweak precision observables. For models that satisfy these constraints and that produce a strong first order phase transition, we discuss the prospective signatures in future Higgs studies at the Large Hadron Collider and a Linear Collider. We argue that such studies will provide powerful probes of phase transition dynamics in models with an extended scalar sector
M1 transitions in the (sdg) boson model
Energy Technology Data Exchange (ETDEWEB)
Kuyucak, S.; Morrison, I.
1988-03-03
Using the 1/N expansion technique we derive expressions for ..beta.. -> g, ..gamma.. -> g and ..gamma.. -> ..gamma.. M1 transitions in a general boson model. The M1 matrix elements in the sdg-boson model are similar in form to those in the neutron-proton IBM. Comparisons are made to some selected M1 data exhibiting collective character.
Description of transitional nuclei in the sdg boson model
International Nuclear Information System (INIS)
Lac, V.S.; Kuyucak, S.
1992-01-01
We study the transitional nuclei in the framework of the sdg boson model. This extension is necessitated by recent measurements of E2 and E4 transitions in the Pt and Os isotopes which can not be explained in the sd boson models. We show how γ-unstable and triaxial shapes arise from special choices of sdg model hamiltonians and discuss ways of limiting the number of free parameters through consistency and coherence conditions. A satisfactory description of E2 and E4 properties is obtained for the Pt and Os nuclei, which also predicts dynamic shape transitions in these nuclei. (orig.)
Description of transitional nuclei in the sdg boson model
Lac, V.-S.; Kuyucak, S.
1992-03-01
We study the transitional nuclei in the framework of the sdg boson model. This extension is necessitated by recent measurements of E2 and E4 transitions in the Pt and Os isotopes which can not be explained in the sd boson models. We show how γ-unstable and triaxial shapes arise from special choices of sdg model hamiltonians and discuss ways of limiting the number of free parameters through consistency and coherence conditions. A satisfactory description of E2 and E4 properties is obtained for the Pt and Os nuclei, which also predicts dynamic shape transitions in these nuclei.
Description of transitional nuclei in the sdg boson model
Energy Technology Data Exchange (ETDEWEB)
Lac, V.S.; Kuyucak, S. (School of Physics, Univ. Melbourne, Victoria (Australia))
1992-03-30
We study the transitional nuclei in the framework of the sdg boson model. This extension is necessitated by recent measurements of E2 and E4 transitions in the Pt and Os isotopes which can not be explained in the sd boson models. We show how {gamma}-unstable and triaxial shapes arise from special choices of sdg model hamiltonians and discuss ways of limiting the number of free parameters through consistency and coherence conditions. A satisfactory description of E2 and E4 properties is obtained for the Pt and Os nuclei, which also predicts dynamic shape transitions in these nuclei. (orig.).
M1 transitions in the (sdg) boson model
Kuyucak, S.; Morrison, I.
1988-03-01
Using the {1}/{N} expansion technique we derive expressions for β→g, γ→g and γ→γ M1 transitions in a general boson model. The M1 matrix elements in the sdg-boson model are similar in form to those in the neutron-proton IBM. Comparisons are made to some selected M1 data exhibiting collective character.
M1 transitions in the (sdg) boson model
International Nuclear Information System (INIS)
Kuyucak, S.; Tuebingen Univ.; Morrison, I.
1988-01-01
Using the 1/N expansion technique we derive expressions for β → g, γ → g and γ → γ M1 transitions in a general boson model. The M1 matrix elements in the sdg-boson model are similar in form to those in the neutron-proton IBM. Comparisons are made to some selected M1 data exhibiting collective character. (orig.)
Description of transitional nuclei in the sdg boson model
International Nuclear Information System (INIS)
Lac, V.S.; Kuyucak, S.
1992-01-01
The study of the transitional nuclei in the framework of the sdg boson model was necessitated by recent measurements of E2 and E4 transitions in the Pt and Os isotopes which can not be explained in the sd boson models. It is shown how γ-unstable and triaxial shapes arise from special choices of sdg model Hamiltonians. Ways of limiting the number of free parameters through consistency and coherence conditions are also discussed. A satisfactory description of E2 and E4 properties is obtained for the Pt and Os nuclei, which also predicts dynamic shape transitions in these nuclei. 36 refs., 10 tabs., 12 figs
Quantum phase transitions in atomic nuclei
International Nuclear Information System (INIS)
Zamfir, N.V.
2005-01-01
Studies of quantum phase transitions in mesoscopic systems and applications to atomic nuclei are presented. Analysis in terms of the Interacting Boson Model shows that the main features persist even for moderate number of particles. Experimental evidence in rare-earth nuclei is discussed. New order and control parameters for systems with the same number of particles are proposed. (author)
Anomalous dimension, chiral phase transition and inverse magnetic catalysis in soft-wall AdS/QCD
Energy Technology Data Exchange (ETDEWEB)
Fang, Zhen, E-mail: fangzhen@itp.ac.cn [Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Science, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing (China)
2016-07-10
A modified soft-wall AdS/QCD model with a z-dependent bulk scalar mass is proposed. We argue for the necessity of a modified bulk scalar mass from the quark mass anomalous dimension and carefully constrain the form of bulk mass by the corresponding UV and IR asymptotics. After fixing the form of bulk scalar mass, we calculate the mass spectra of (axial-)vector and pseudoscalar mesons, which have a good agreement with the experimental data. The behavior of chiral phase transition is also investigated, and the results are consistent with the standard scenario and lattice simulations. Finally, the issue of chiral magnetic effects is addressed. We find that the inverse magnetic catalysis emerges naturally from the modified soft-wall model, which is consistent with the recent lattice simulations.
Bartz, Sean P.; Jacobson, Theodore
2018-04-01
The phase transition from hadronic matter to chirally symmetric quark-gluon plasma is expected to be a rapid crossover at zero quark chemical potential (μ ), becoming first order at some finite value of μ , indicating the presence of a critical point. Using a three-flavor soft-wall model of anti-de Sitter/QCD, we investigate the effect of varying the light and strange quark masses on the order of the chiral phase transition. At zero quark chemical potential, we reproduce the Columbia Plot, which summarizes the results of lattice QCD and other holographic models. We then extend this holographic model to examine the effects of finite quark chemical potential. We find that the the chemical potential does not affect the critical line that separates first-order from rapid crossover transitions. This excludes the possibility of a critical point in this model, suggesting that a different setup is necessary to reproduce all the features of the QCD phase diagram.
Microscopic origin of black hole reentrant phase transitions
Zangeneh, M. Kord; Dehyadegari, A.; Sheykhi, A.; Mann, R. B.
2018-04-01
Understanding the microscopic behavior of the black hole ingredients has been one of the important challenges in black hole physics during the past decades. In order to shed some light on the microscopic structure of black holes, in this paper, we explore a recently observed phenomenon for black holes namely reentrant phase transition, by employing the Ruppeiner geometry. Interestingly enough, we observe two properties for the phase behavior of small black holes that leads to reentrant phase transition. They are correlated and they are of the interaction type. For the range of pressure in which the system underlies reentrant phase transition, it transits from the large black holes phase to the small one which possesses higher correlation than the other ranges of pressures. On the other hand, the type of interaction between small black holes near the large/small transition line differs for usual and reentrant phase transitions. Indeed, for the usual case, the dominant interaction is repulsive whereas for the reentrant case we encounter an attractive interaction. We show that in the reentrant phase transition case, the small black holes behave like a bosonic gas whereas in the usual phase transition case, they behave like a quantum anyon gas.
Dynamic shape transitions in the sdg boson model
Kuyucak, S.
The dynamic evolution of shapes in the sdg interacting boson model is investigated using the angular momentum projected mean field theory. Deformed nuclei are found to be quite stable against shape changes but transitional nuclei could exhibit dynamic shape transitions in the region L = 10-20. Conditions of existence and experimental signatures for dynamic shape transitions are discussed together with a likely candidate, 192Os.
Yoon, Beom-Jin; Park, Jung Ok; Srinivasarao, Mohan; Smith, Michael H.; Lyon, L. Andrew
2011-03-01
The structure and dynamics of soft matter were studied by differential dynamic optical microscopy. One can retrieve q-space information through image processing and Fourier analysis, even when the feature sizes in real space image are too small to be resolved or even visible in an optical microscope. The temporal sequence of real space images were Fourier transformed, and analyzed for the temporal and spatial fluctuations of power spectrum. Here, we present the results on liquid crystal dynamics and their elastic properties, volume phase transition of hydrogels when their dimensions are sub-micron, and critical opalescence of binary mixtures (water/2,6-lutidine).
Dynamic shape transitions in the sdg boson model
International Nuclear Information System (INIS)
Kuyucak, S.
1992-01-01
The dynamic evolution of shapes in the sdg interacting boson model is investigated using the angular momentum projected mean field theory. Deformed nuclei are found to be quite stable against shape changes but transitional nuclei could exhibit dynamic shape transitions in the region L = 10-20. Conditions of existence and experimental signatures for dynamic shape transitions are discussed together with a likely candidate, 192 Os. 13 refs., 3 figs
Quantum phase transition in the U(4) vibron model and the E(3) symmetry
International Nuclear Information System (INIS)
Zhang Yu; Hou Zhanfeng; Chen Huan; Wei Haiqing; Liu Yuxin
2008-01-01
We study the details of the U(3)-O(4) quantum phase transition in the U(4) vibron model. Both asymptotic analysis in the classical limit and rigorous calculations for finite boson number systems indicate that a second-order phase transition is still there even for the systems with boson number N ranging from tens to hundreds. Two kinds of effective order parameters, including E1 transition ratios B(E1:2 1 →1 1 )/B(E1:1 1 →0 1 ) and B(E1:0 2 →1 1 )/B(E1:1 1 →0 1 ), and the energy ratios E 2 1 /E 0 2 and E 3 1 /E 0 2 are proposed to identify the second-order phase transition in experiments. We also found that the critical point of phase transition can be approximately described by the E(3) symmetry, which persists even for moderate N∼10 protected by the scaling behaviors of quantities at the critical point. In addition, a possible empirical example exhibiting roughly the E(3) symmetry is discussed
Electroweak phase transition in two Higgs doublet models
International Nuclear Information System (INIS)
Cline, J.M.; Lemieux, P.
1997-01-01
We reexamine the strength of the first-order phase transition in the electroweak theory supplemented by an extra Higgs doublet. The finite-temperature effective potential V eff is computed to one-loop order, including the summation of ring diagrams, to study the ratio φ c /T c of the Higgs field VEV to the critical temperature. We make a number of improvements over previous treatments, including a consistent treatment of Goldstone bosons in V eff , an accurate analytic approximation to V eff valid for any mass-to-temperature ratios, and use of the experimentally measured top quark mass. For two-Higgs-doublet models, we identify a significant region of parameter space where φ c /T c is large enough for electroweak baryogenesis, and we argue that this identification should persist even at higher orders in perturbation theory. In the case of the minimal supersymmetric standard model, our results indicate that the extra Higgs bosons have little effect on the strength of the phase transition. copyright 1997 The American Physical Society
Neutron and x-ray scattering studies of ferroelectric phase transitions
International Nuclear Information System (INIS)
Dolling, G.
1982-08-01
The subject of ferroelectric type phase transitions is introduced by means of examples of two main classes (a) displacive transitions, e.g. KNbO 3 , and (b) order-disorder transitions, e.g. NaNO 2 . The significance of crystal structure and crystal dynamics (i.e. the phonon dispersion relations) for ferroelectric behaviour is emphasized. The chief methods for structure determination are x-ray and neutron diffraction, while the most powerful of all techniques for studying phonon properties is that of coherent inelastic neutron scattering. The most useful type of neutron spectrometer for phase transition studies, the triple axis crystal spectrometer, is discussed in detail. The history of the soft mode theory of displacive phase transitions, and its application to the antiferroelectric and 'almost ferroelectric' transitions in SrTiO 3 , provides an introduction to more recent developments in this area, including over-damped soft modes, central peaks and critical scattering, incommensurate phase transitions (e.g. K 2 SeO 4 ), amplitudons, phasons and finally solitions. The treatment throughout is descriptive and introductory, designed for graduate students
Continuous Easy-Plane Deconfined Phase Transition on the Kagome Lattice
Zhang, Xue-Feng; He, Yin-Chen; Eggert, Sebastian; Moessner, Roderich; Pollmann, Frank
2018-03-01
We use large scale quantum Monte Carlo simulations to study an extended Hubbard model of hard core bosons on the kagome lattice. In the limit of strong nearest-neighbor interactions at 1 /3 filling, the interplay between frustration and quantum fluctuations leads to a valence bond solid ground state. The system undergoes a quantum phase transition to a superfluid phase as the interaction strength is decreased. It is still under debate whether the transition is weakly first order or represents an unconventional continuous phase transition. We present a theory in terms of an easy plane noncompact C P1 gauge theory describing the phase transition at 1 /3 filling. Utilizing large scale quantum Monte Carlo simulations with parallel tempering in the canonical ensemble up to 15552 spins, we provide evidence that the phase transition is continuous at exactly 1 /3 filling. A careful finite size scaling analysis reveals an unconventional scaling behavior hinting at deconfined quantum criticality.
The electro-magnetic transition properties in the microscopic SDG interacting boson model
International Nuclear Information System (INIS)
Han Guangze; Liu Yong; Sang Jianping
1996-01-01
A bosonic method and the corresponding fermionic one for studying the electro-magnetic transition properties of nucleus are presented in the microscopic sdg interacting boson model. The methods are applied to the nucleus 60 Ni. Detailed discussions are made with the calculated results
Non-equilibrium phase transitions in complex plasma
International Nuclear Information System (INIS)
Suetterlin, K R; Raeth, C; Ivlev, A V; Thomas, H M; Khrapak, S; Zhdanov, S; Rubin-Zuzic, M; Morfill, G E; Wysocki, A; Loewen, H; Goedheer, W J; Fortov, V E; Lipaev, A M; Molotkov, V I; Petrov, O F
2010-01-01
Complex plasma being the 'plasma state of soft matter' is especially suitable for investigations of non-equilibrium phase transitions. Non-equilibrium phase transitions can manifest in dissipative structures or self-organization. Two specific examples are lane formation and phase separation. Using the permanent microgravity laboratory PK-3 Plus, operating onboard the International Space Station, we performed unique experiments with binary mixtures of complex plasmas that showed both lane formation and phase separation. These observations have been augmented by comprehensive numerical and theoretical studies. In this paper we present an overview of our most important results. In addition we put our results in context with research of complex plasmas, binary systems and non-equilibrium phase transitions. Necessary and promising future complex plasma experiments on phase separation and lane formation are briefly discussed.
Virtual processes and superradiance in spin-boson modes
International Nuclear Information System (INIS)
Alcalde, M. Aparicio; Kullock, R.; Svaiter, N.F.
2008-01-01
We consider spin-boson models composed by a single bosonic mode and an ensemble of N identical two-level atoms. The situation where the coupling between the bosonic mode and the atoms generates real and virtual processes is studied, where the whole system is in thermal equilibrium with a reservoir at temperature β -1 . Phase transitions from ordinary fluorescence to super radiant phase in three different models is investigated. First a model where the coupling between the bosonic mode and the j - th atom is via the pseudo-spin operator σ (j) z is studied. Second, we investigate the generalized Dicke model, introducing different coupling constants between the single mode bosonic field and the environment, g 1 and g 2 for rotating and counter-rotating terms, respectively. Finally it is considered a modified version of the generalized Dicke model with intensity-dependent coupling in the rotating terms. In the first model the zero mode contributes to render the canonical entropy a negative quantity for low temperatures. The last two models presents phase transitions, even when only Hamiltonian terms which generates virtual processes are considered. (author)
Strong first order electroweak phase transition in the CP-conserving 2HDM revisited
International Nuclear Information System (INIS)
Basler, P.; Krause, M.; Mühlleitner, M.; Wittbrodt, J.; Wlotzka, A.
2017-01-01
The discovery of the Higgs boson by the LHC experiments ATLAS and CMS has marked a milestone for particle physics. Yet, there are still many open questions that cannot be answered within the Standard Model (SM). For example, the generation of the observed matter-antimatter asymmetry in the universe through baryogenesis can only be explained qualitatively in the SM. A simple extension of the SM compatible with the current theoretical and experimental constraints is given by the 2-Higgs-Doublet Model (2HDM) where a second Higgs doublet is added to the Higgs sector. We investigate the possibility of a strong first order electroweak phase transition in the CP-conserving 2HDM type I and type II where either of the CP-even Higgs bosons is identified with the SM-like Higgs boson. The renormalisation that we apply on the loop-corrected Higgs potential allows us to efficiently scan the 2HDM parameter space and simultaneously take into account all relevant theoretical and up-to-date experimental constraints. The 2HDM parameter regions found to be compatible with the applied constraints and a strong electroweak phase transition are analysed systematically. Our results show that there is a strong interplay between the requirement of a strong phase transition and collider phenomenology with testable implications for searches at the LHC.
Strong first order electroweak phase transition in the CP-conserving 2HDM revisited
Energy Technology Data Exchange (ETDEWEB)
Basler, P.; Krause, M.; Mühlleitner, M. [Institute for Theoretical Physics, Karlsruhe Institute of Technology,Wolfgang-Gaede-Str. 1, 76131 Karlsruhe (Germany); Wittbrodt, J. [Institute for Theoretical Physics, Karlsruhe Institute of Technology,Wolfgang-Gaede-Str. 1, 76131 Karlsruhe (Germany); Deutsches Elektronen-Synchrotron DESY,Notkestraße 85, D-22607 Hamburg (Germany); Wlotzka, A. [Institute for Theoretical Physics, Karlsruhe Institute of Technology,Wolfgang-Gaede-Str. 1, 76131 Karlsruhe (Germany)
2017-02-23
The discovery of the Higgs boson by the LHC experiments ATLAS and CMS has marked a milestone for particle physics. Yet, there are still many open questions that cannot be answered within the Standard Model (SM). For example, the generation of the observed matter-antimatter asymmetry in the universe through baryogenesis can only be explained qualitatively in the SM. A simple extension of the SM compatible with the current theoretical and experimental constraints is given by the 2-Higgs-Doublet Model (2HDM) where a second Higgs doublet is added to the Higgs sector. We investigate the possibility of a strong first order electroweak phase transition in the CP-conserving 2HDM type I and type II where either of the CP-even Higgs bosons is identified with the SM-like Higgs boson. The renormalisation that we apply on the loop-corrected Higgs potential allows us to efficiently scan the 2HDM parameter space and simultaneously take into account all relevant theoretical and up-to-date experimental constraints. The 2HDM parameter regions found to be compatible with the applied constraints and a strong electroweak phase transition are analysed systematically. Our results show that there is a strong interplay between the requirement of a strong phase transition and collider phenomenology with testable implications for searches at the LHC.
Mixtures of bosonic and fermionic atoms in optical lattices
International Nuclear Information System (INIS)
Albus, Alexander; Illuminati, Fabrizio; Eisert, Jens
2003-01-01
We discuss the theory of mixtures of bosonic and fermionic atoms in periodic potentials at zero temperature. We derive a general Bose-Fermi Hubbard Hamiltonian in a one-dimensional optical lattice with a superimposed harmonic trapping potential. We study the conditions for linear stability of the mixture and derive a mean-field criterion for the onset of a bosonic superfluid transition. We investigate the ground-state properties of the mixture in the Gutzwiller formulation of mean-field theory, and present numerical studies of finite systems. The bosonic and fermionic density distributions and the onset of quantum phase transitions to demixing and to a bosonic Mott-insulator are studied as a function of the lattice potential strength. The existence is predicted of a disordered phase for mixtures loaded in very deep lattices. Such a disordered phase possessing many degenerate or quasidegenerate ground states is related to a breaking of the mirror symmetry in the lattice
Phase transition with trivial quantum criticality in an anisotropic Weyl semimetal
Li, Xin; Wang, Jing-Rong; Liu, Guo-Zhu
2018-05-01
When a metal undergoes continuous quantum phase transition, the correlation length diverges at the critical point and the quantum fluctuation of order parameter behaves as a gapless bosonic mode. Generically, the coupling of this boson to fermions induces a variety of unusual quantum critical phenomena, such as non-Fermi liquid behavior and various emergent symmetries. Here, we perform a renormalization group analysis of the semimetal-superconductor quantum criticality in a three-dimensional anisotropic Weyl semimetal. Surprisingly, distinct from previously studied quantum critical systems, the anomalous dimension of anisotropic Weyl fermions flows to zero very quickly with decreasing energy, and the quasiparticle residue takes a nonzero value. These results indicate that the quantum fluctuation of superconducting order parameter is irrelevant at low energies, and a simple mean-field calculation suffices to capture the essential physics of the superconducting transition. We thus obtain a phase transition that exhibits trivial quantum criticality, which is unique comparing to other invariably nontrivial quantum critical systems. Our theoretical prediction can be experimentally verified by measuring the fermion spectral function and specific heat.
Energy Technology Data Exchange (ETDEWEB)
Stasyuk, I.V.; Krasnov, V.O., E-mail: krasnoff@icmp.lviv.ua
2017-04-15
Phase transitions at non-zero temperatures in ultracold Bose- and Fermi-particles mixture in optical lattices using the Bose-Fermi-Hubbard model in the mean field and hard-core boson approximations are investigated. The case of infinitely small fermion transfer and the repulsive on-site boson-fermion interaction is considered. The possibility of change of order (from the 2nd to the 1st one) of the phase transition to the superfluid phase in the regime of fixed values of the chemical potentials of Bose- and Fermi-particles is established. The relevant phase diagrams determining the conditions at which such a change takes place, are built.
Higgs bosons and other mechanisms of mass generation
International Nuclear Information System (INIS)
Konopleva, N. P.
1997-01-01
There are two problems under discuss here: 1) are Higgs bosons really necessary for the gauge field mass generation or not, and 2) why are Higgs bosons invisible in the elementary particles experiments? It is shown that in the frame of the classical Lagrangian gauge fields theory the transition from the usual variational problem to isoperimetric one permits us to conserve the local gauge invariance on the solutions of the massive gauge field theory equations. Hence in the massive gauge field theory we can have on the field equation solutions not only the conservation laws corresponding with the first Noether's theorem but Noether's identities corresponding with the second Noether's theorem also. Therefore the alternative renormalization procedure can exist which does not demand of Higgs bosons appearance in the massive gauge field theory for its renormalizability. The interpretation of Higgs mechanism as the phase transition mechanism is discussed. From this point of view the inexplicable absence of the individual Higgs bosons could be the result of the fact that the massive gauge field is the complex system of the massless gauge fields interacting with the condensate of Higgs bosons and quantum vortices in it. In this case the gauge field obtains the mass when the phase transition happens and after that the individual Higgs bosons can not be eliminated from the complex system
Quantum phase transition of light in the Rabi–Hubbard model
International Nuclear Information System (INIS)
Schiró, M; Bordyuh, M; Öztop, B; Türeci, H E
2013-01-01
We discuss the physics of the Rabi–Hubbard model describing large arrays of coupled cavities interacting with two level atoms via a Rabi nonlinearity. We show that the inclusion of counter-rotating terms in the light–matter interaction, often neglected in theoretical descriptions based on Jaynes–Cumming models, is crucial to stabilize finite-density quantum phases of correlated photons with no need for an artificially engineered chemical potential. We show that the physical properties of these phases and the quantum phase transition occurring between them is remarkably different from those of interacting bosonic massive quantum particles. The competition between photon delocalization and Rabi nonlinearity drives the system across a novel Z 2 parity symmetry-breaking quantum phase transition between two gapped phases, a Rabi insulator and a delocalized super-radiant phase. (paper)
Quantum phase transitional patterns of nuclei
International Nuclear Information System (INIS)
Dai Lianrong; Wang Lixing; Pan Feng; Zhong Weiwei; Liu Qi
2013-01-01
With the framework of Interacting Boson Model (IBM), transitional patterns from the spherical to the axially deformed limit of the IBM with a schematic Hamiltonian are studied by replacing the SU (3) quadrupole-quadrupole term with O (6) cubic interaction. But, we use the two schemes to investigate some energy ratios and B (E2) ratios for different bosons N = 8 and N = 20. The results show that with the increasing of the numbers of bosons, the transitional behaviors can be enhanced; the transitional behaviors are very similar in the two schemes. However, there are some distinctive differences for some quantities across the entire transitional region, such as energy levels and ratios, B (E2) values and ratios, and expectation values of the shape variables. Generally speaking, the transition is smoother and the nuclear shape is less well defined in the new scheme. Then we apply the two schemes to the critical point symmetry candidate, such as 152 Sm, and find the overall fitting quality of the UQ scheme is better than that of the U (5)-SU (3) scheme, especially for the inter-band E2 transitions in 152 Sm. (authors)
Jafarizadeh, M. A.; Ranjbar, Z.; Fouladi, N.; Ghapanvari, M.
2018-01-01
In this paper, a successful algebraic method based on the dual algebraic structure for three level pairing model in the framework of sdg IBM is proposed for transitional nuclei which show transitional behavior from spherical to gamma-unstable quantum shape phase transition. In this method complicated sdg Hamiltonian, which is a three level pairing Hamiltonian is determined easily via the exactly solvable method. This description provides a better interpretation of some observables such as BE (4) in nuclei which exhibits the necessity of inclusion of g boson in the sd IBM, while BE (4) cannot be explained in the sd boson model. Some observables such as Energy levels, BE (2), BE (4), the two neutron separation energies signature splitting of the γ-vibrational band and expectation values of the g-boson number operator are calculated and examined for 46 104 - 110Pd isotopes.
A perturbative RS I cosmological phase transition
Energy Technology Data Exchange (ETDEWEB)
Bunk, Don [Skidmore College, Department of Physics, Saratoga Springs, NY (United States); Hubisz, Jay [Syracuse University, Department of Physics, Syracuse, NY (United States); Jain, Bithika [Korea Institute for Advanced Study, School of Physics, Seoul (Korea, Republic of)
2018-01-15
We identify a class of Randall-Sundrum type models with a successful first order cosmological phase transition during which a 5D dual of approximate conformal symmetry is spontaneously broken. Our focus is on soft-wall models that naturally realize a light radion/dilaton and suppressed dynamical contribution to the cosmological constant. We discuss phenomenology of the phase transition after developing a theoretical and numerical analysis of these models both at zero and finite temperature. We demonstrate a model with a TeV-Planck hierarchy and with a successful cosmological phase transition where the UV value of the curvature corresponds, via AdS/CFT, to an N of 20, where 5D gravity is expected to be firmly in the perturbative regime. (orig.)
Electroweak phase transition in an extension of the standard model with scalar color octet
International Nuclear Information System (INIS)
Ham, S. W.; Shim, Seong-A; Oh, S. K.
2010-01-01
In an extension of the standard model with a scalar color octet, the possibility of the strongly first-order electroweak phase transition is studied by examining the finite-temperature effective Higgs potential at the one-loop level. It is found that there are wide regions in the parameter space that allow the strongly first-order electroweak phase transition, where the Higgs boson mass is larger than the experimental lower bound of 115 GeV, and the masses of the scalar color octet is around 200 GeV. The parameter regions may be explored at the LHC with respect to the electroweak phase transition.
Ground states of a spin-boson model
International Nuclear Information System (INIS)
Amann, A.
1991-01-01
Phase transition with respect to ground states of a spin-boson Hamiltonian are investigated. The spin-boson model under discussion consists of one spin and infinitely many bosons with a dipole-type coupling. It is shown that the order parameter of the model vanishes with respect to arbitrary ground states if it vanishes with respect to ground states obtained as (biased) temperature to zero limits of thermic equilibrium states. The ground states of the latter special type have been investigated by H. Spohn. Spohn's respective phase diagrams are therefore valid for arbitrary ground states. Furthermore, disjointness of ground states in the broken symmetry regime is examined
Soft gluon resummation for the single-spin production of W±-bosons
International Nuclear Information System (INIS)
Weber, A.
1993-01-01
We carefully study the production of W ± -bosons in singly-polarized hadron-hadron collisions. In the region of small transverse momenta of the produced W ± we perform the soft gluon resummation to double logarithmic accuracy. Special emphasis is laid on matching the resummed expression to the O(α s ) perturbative result valid at large transverse momenta. We investigate the phenomenological relevance of our results for pp-collisions at RHIC and show that in the future single-spin W ± -production may help to shed more light on the surprising EMC-result. (orig.)
Glass transition of soft colloids
Philippe, Adrian-Marie; Truzzolillo, Domenico; Galvan-Myoshi, Julian; Dieudonné-George, Philippe; Trappe, Véronique; Berthier, Ludovic; Cipelletti, Luca
2018-04-01
We explore the glassy dynamics of soft colloids using microgels and charged particles interacting by steric and screened Coulomb interactions, respectively. In the supercooled regime, the structural relaxation time τα of both systems grows steeply with volume fraction, reminiscent of the behavior of colloidal hard spheres. Computer simulations confirm that the growth of τα on approaching the glass transition is independent of particle softness. By contrast, softness becomes relevant at very large packing fractions when the system falls out of equilibrium. In this nonequilibrium regime, τα depends surprisingly weakly on packing fraction, and time correlation functions exhibit a compressed exponential decay consistent with stress-driven relaxation. The transition to this novel regime coincides with the onset of an anomalous decrease in local order with increasing density typical of ultrasoft systems. We propose that these peculiar dynamics results from the combination of the nonequilibrium aging dynamics expected in the glassy state and the tendency of colloids interacting through soft potentials to refluidize at high packing fractions.
Peng, Yan
2017-07-01
We study a general flat space/boson star transition model in quasi-local ensemble through approaches familiar from holographic superconductor theories. We manage to find a parameter ψ 2, which is proved to be useful in disclosing properties of phase transitions. In this work, we explore effects of the scalar mass, scalar charge and Stückelberg mechanism on the critical phase transition points and the order of transitions mainly from behaviors of the parameter ψ 2. We mention that properties of transitions in quasi-local gravity are strikingly similar to those in holographic superconductor models. We also obtain an analytical relation ψ 2 ∝ ( μ - μ c )1/2, which also holds for the condensed scalar operator in the holographic insulator/superconductor system in accordance with mean field theories.
Directory of Open Access Journals (Sweden)
Böyükata M.
2014-03-01
Full Text Available Quantum phase transitions in odd-nuclei are investigated within the framework of the interacting boson-fermion model with a description based on the concept of intrinsic states. We consider the case of a single j=9/2 odd-particle coupled to an even-even boson core that performs a transition from spherical to deformed prolate and to deformed gamma-unstable shapes varying a control parameter in the boson Hamiltonian. The effect of the coupling of the odd particle to this core is discussed along the shape transition and, in particular, at the critical point.
Quantum entanglement and phase transition in a two-dimensional photon-photon pair model
International Nuclear Information System (INIS)
Zhang Jianjun; Yuan Jianhui; Zhang Junpei; Cheng Ze
2013-01-01
We propose a two-dimensional model consisting of photons and photon pairs. In the model, the mixed gas of photons and photon pairs is formally equivalent to a two-dimensional system of massive bosons with non-vanishing chemical potential, which implies the existence of two possible condensate phases. Using the variational method, we discuss the quantum phase transition of the mixed gas and obtain the critical coupling line analytically. Moreover, we also find that the phase transition of the photon gas can be interpreted as enhanced second harmonic generation. We then discuss the entanglement between photons and photon pairs. Additionally, we also illustrate how the entanglement between photons and photon pairs can be associated with the phase transition of the system.
Supersymmetric phase transition in Josephson-tunnel-junction arrays
Energy Technology Data Exchange (ETDEWEB)
Foda, O.
1988-08-31
The fully frustrated XY model in two dimensions exhibits a vortex-unbinding as well as an Ising transition. If the Ising transition overlaps with the critical line that ends on the vortex transition: T/sub I/less than or equal toT/sub V/, then the model is equivalent, at the overlap temperature, to a free massless field theory of 1 boson and 1 Majorana fermion, which is a superconformal field theory, of central charge c=3/2. The model is experimentally realized in terms of an array of Josephson-tunnel junctions in a transverse magnetic field. The experiment reveals a phase transition consistent with T/sub I/=T/sub V/. Thus, at the critical temperature, the array provides a physical realization of a supersymmetric quantum field theory.
A supersymmetric phase transition in Josephson-tunnel-junction arrays
International Nuclear Information System (INIS)
Foda, O.
1988-01-01
The fully frustrated XY model in two dimensions exhibits a vortex-unbinding as well as an Ising transition. If the Ising transition overlaps with the critical line that ends on the vortex transition: T I ≤T V , then the model is equivalent, at the overlap temperature, to a free massless field theory of 1 boson and 1 Majorana fermion, which is a superconformal field theory, of central charge c=3/2. The model is experimentally realized in terms of an array of Josephson-tunnel junctions in a transverse magnetic field. The experiment reveals a phase transition consistent with T I =T V . Thus, at the critical temperature, the array provides a physical realization of a supersymmetric quantum field theory. (orig.)
Numerical tests of the electroweak phase transition and thermodynamics of the electroweak plasma
Csikor, Ferenc; Hein, J; Jaster, A; Montvay, István
1996-01-01
The finite temperature phase transition in the SU(2) Higgs model at a Higgs boson mass M_H \\simeq 34 GeV is studied in numerical simulations on four-dimensional lattices with time-like extensions up to L_t=5. The effects of the finite volume and finite lattice spacing on masses and couplings are studied in detail. The errors due to uncertainties in the critical hopping parameter are estimated. The thermodynamics of the electroweak plasma near the phase transition is investigated by determining the relation between energy density and pressure.
Influence of trapping potentials on the phase diagram of bosonic atoms in optical lattices
International Nuclear Information System (INIS)
Giampaolo, S.M.; Illuminati, F.; Mazzarella, G.; De Siena, S.
2004-01-01
We study the effect of external trapping potentials on the phase diagram of bosonic atoms in optical lattices. We introduce a generalized Bose-Hubbard Hamiltonian that includes the structure of the energy levels of the trapping potential, and show that these levels are in general populated both at finite and zero temperature. We characterize the properties of the superfluid transition for this situation and compare them with those of the standard Bose-Hubbard description. We briefly discuss similar behaviors for fermionic systems
Gravitational waves from a very strong electroweak phase transition
Energy Technology Data Exchange (ETDEWEB)
Leitao, Leonardo; Mégevand, Ariel, E-mail: lleitao@mdp.edu.ar, E-mail: megevand@mdp.edu.ar [IFIMAR (UNMdP-CONICET), Departamento de Física, Facultad de Ciencias Exactas y Naturales, UNMdP, Deán Funes 3350, (7600) Mar del Plata (Argentina)
2016-05-01
We investigate the production of a stochastic background of gravitational waves in the electroweak phase transition. We consider extensions of the Standard Model which can give very strongly first-order phase transitions, such that the transition fronts either propagate as detonations or run away. To compute the bubble wall velocity, we estimate the friction with the plasma and take into account the hydrodynamics. We track the development of the phase transition up to the percolation time, and we calculate the gravitational wave spectrum generated by bubble collisions, magnetohydrodynamic turbulence, and sound waves. For the kinds of models we consider, we find parameter regions for which the gravitational waves are potentially observable at the planned space-based interferometer eLISA. In such cases, the signal from sound waves is generally dominant, while that from bubble collisions is the least significant of them. Since the sound waves and turbulence mechanisms are diminished for runaway walls, the models with the best prospects of detection at eLISA are those which do not have such solutions. In particular, we find that heavy extra bosons provide stronger gravitational wave signals than tree-level terms.
Moskvin, A. S.; Panov, Yu. D.; Rybakov, F. N.; Borisov, A. B.
2017-11-01
We have used high-performance parallel computations by NVIDIA graphics cards applying the method of nonlinear conjugate gradients and Monte Carlo method to observe directly the developing ground state configuration of a two-dimensional hard-core boson system with decrease in temperature, and its evolution with deviation from a half-filling. This has allowed us to explore unconventional features of a charge order—superfluidity phase transition, specifically, formation of an irregular domain structure, emergence of a filamentary superfluid structure that condenses within of the charge-ordered phase domain antiphase boundaries, and formation and evolution of various topological structures.
Nonequilibrium dynamics of spin-boson models from phase-space methods
Piñeiro Orioli, Asier; Safavi-Naini, Arghavan; Wall, Michael L.; Rey, Ana Maria
2017-09-01
An accurate description of the nonequilibrium dynamics of systems with coupled spin and bosonic degrees of freedom remains theoretically challenging, especially for large system sizes and in higher than one dimension. Phase-space methods such as the truncated Wigner approximation (TWA) have the advantage of being easily scalable and applicable to arbitrary dimensions. In this work we adapt the TWA to generic spin-boson models by making use of recently developed algorithms for discrete phase spaces [J. Schachenmayer, A. Pikovski, and A. M. Rey, Phys. Rev. X 5, 011022 (2015), 10.1103/PhysRevX.5.011022]. Furthermore we go beyond the standard TWA approximation by applying a scheme based on the Bogoliubov-Born-Green-Kirkwood-Yvon (BBGKY) hierarchy of equations to our coupled spin-boson model. This allows us, in principle, to study how systematically adding higher-order corrections improves the convergence of the method. To test various levels of approximation we study an exactly solvable spin-boson model, which is particularly relevant for trapped-ion arrays. Using TWA and its BBGKY extension we accurately reproduce the time evolution of a number of one- and two-point correlation functions in several dimensions and for an arbitrary number of bosonic modes.
International Nuclear Information System (INIS)
Zhang Aixia; Xue Jukui
2012-01-01
We propose a scheme to reveal the interplay between dipole–dipole interaction (DDI), inter-level coupling and macroscopic phase transitions in dipolar condensates. By considering a macroscopic sample of dipolar bosons in triple-well potentials, DDI-induced coupling between the inter-level physics and the macroscopic phase transitions is presented. When the DDI exceeds certain thresholds, the degeneracy of the two lowest energy levels and the excitation of new eigenstates occur, respectively. Interestingly, these thresholds give the boundaries of various quantum phase transitions. That is, the quantum phase transitions are the consequence of the levels' degeneracy and the new eigenstates' excitation. Furthermore, DDI-induced long-range macroscopic Josephson oscillations are observed and long-range coherent quantum transportation is achieved. Our results give clear proof of the interplay between the multi-level physics and quantum phase transitions, and also provide a way for designing the long-range coherent quantum transportation. (paper)
International Nuclear Information System (INIS)
Wang Xiguang; Guo Guanghua; Zhang Guangfu
2011-01-01
The demagnetization processes of antiferromagnetically exchange-coupled hard/soft/hard trilayer structures have been studied based on the discrete one-dimensional atomic chain model and the linear partial domain-wall model. It is found that, when the magnetic anisotropy of soft layer is taken into account, the changes of the soft layer thickness and the interfacial exchange coupling strength may lead a transition of demagnetization process in soft layer from the reversible to the irreversible magnetic exchange-spring process. For the trilayer structures with very thin soft layer, the demagnetization process exhibits typical reversible exchange-spring behavior. However, as the thickness of soft layer is increased, there is a crossover point t c , after which the process becomes irreversible. Similarly, there is also a critical interfacial exchange coupling constant A sh c , above which the exchange-spring process is reversible. When A sh sh c , the irreversible exchange-spring process is achieved. The phase diagram of reversible and irreversible exchange-spring processes is mapped in the plane of the interfacial exchange coupling A sh and soft layer thickness N s . - Research highlights: → A differing magnetic exchange-spring process is found in antiferromagnetically exchange-coupled hard/soft/hard trilayers if the magnetic anisotropy of the soft layers is taken into account. → The change of the soft layer thickness may lead to a transition of demagnetization process in soft layer from the reversible to the irreversible exchange-spring process. → The change of the soft-hard interfacial exchange coupling strength may lead a transition of demagnetization process in soft layer from the reversible to the irreversible exchange-spring process. → The phase diagram of reversible and irreversible exchange-spring processes is mapped in the plane of the interfacial exchange coupling and soft layer thickness.
The interacting boson model with the high spin bosons
International Nuclear Information System (INIS)
Mizusaki, T.; Otsuka, T.; Yoshinaga, N.
1991-01-01
The phenomenological study in the Ra region was carried out from the view of the sdg-IBM2. The sdg hamiltonian whose parameters are almost kept constant for the isotopes can successfully describe the spherical-deformed phase transition of the Ra isotopes and the enhancement of the moment of inertia of the β band. We emphasize that the role of the g boson is important in the actinide region. (author)
The Physics of Structural Phase Transitions
Fujimoto, Minoru
2005-01-01
Phase transitions in which crystalline solids undergo structural changes present an interesting problem in the interplay between the crystal structure and the ordering process that is typically nonlinear. Intended for readers with prior knowledge of basic condensed-matter physics, this book emphasizes the physics behind spontaneous structural changes in crystals. Starting with the relevant thermodynamic principles, the text discusses the nature of order variables in collective motion in structural phase transitions, where a singularity in such a collective mode is responsible for lattice instability as revealed by soft phonons. In this book, critical anomalies at second-order structural transitions are first analyzed with the condensate model. Discussions on the nonlinear ordering mechanism are followed with the soliton theory, thereby interpreting the role of long-range order. Relevant details for nonlinear mathematics are therefore given for minimum necessity. The text also discusses experimental methods fo...
Mu, ChengFu; Zhang, DaLi
2018-01-01
We investigated the properties of low-lying states in 94Mo within the framework of the proton-neutron interacting boson model (IBM-2), with special focus on the characteristics of mixed-symmetry states. We calculated level energies and M1 and E2 transition strengths. The IBM-2 results agree with the available quantitative and qualitative experimental data on 94Mo. The properties of mixed-symmetry states can be well described by IBM-2 given that the energy of the d proton boson is different from that of the neutron boson, especially for the transition of B( M1; 4 2 + → 4 1 + ).
Chiral phase transition of QCD with N{sub f}=2+1 flavors from holography
Energy Technology Data Exchange (ETDEWEB)
Li, Danning [Department of Physics, Jinan University,Guangzhou 510632 (China); Huang, Mei [Institute of High Energy Physics, Chinese Academy of Sciences,Beijing 100049 (China); University of Chinese Academy of Sciences,Beijing 100049 (China); Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences,Beijing 100049 (China)
2017-02-08
Chiral phase transition for three-flavor N{sub f}=2+1 QCD with m{sub u}=m{sub d}≠m{sub s} is investigated in a modified soft-wall holographic QCD model. Solving temperature dependent chiral condensates from equations of motion of the modified soft-wall model, we extract the quark mass dependence of the order of chiral phase transition in the case of N{sub f}=2+1, and the result is in agreement with the “Columbia Plot”, which is summarized from lattice simulations and other non-perturbative methods. First order phase transition is observed around the three flavor chiral limit m{sub u/d}=0,m{sub s}=0, while at sufficient large quark masses it turns to be a crossover phase transition. The first order and crossover regions are separated by a second order phase transition line. The second order line is divided into two parts by the m{sub u/d}=m{sub s} line, and the m{sub s} dependence of the transition temperature in these two parts are totally contrast, which might indicate that the two parts are governed by different universality classes.
Chiral Floquet Phases of Many-Body Localized Bosons
Directory of Open Access Journals (Sweden)
Hoi Chun Po
2016-12-01
Full Text Available We construct and classify chiral topological phases in driven (Floquet systems of strongly interacting bosons, with finite-dimensional site Hilbert spaces, in two spatial dimensions. The construction proceeds by introducing exactly soluble models with chiral edges, which in the presence of many-body localization (MBL in the bulk are argued to lead to stable chiral phases. These chiral phases do not require any symmetry and in fact owe their existence to the absence of energy conservation in driven systems. Surprisingly, we show that they are classified by a quantized many-body index, which is well defined for any MBL Floquet system. The value of this index, which is always the logarithm of a positive rational number, can be interpreted as the entropy per Floquet cycle pumped along the edge, formalizing the notion of quantum-information flow. We explicitly compute this index for specific models and show that the nontrivial topology leads to edge thermalization, which provides an interesting link between bulk topology and chaos at the edge. We also discuss chiral Floquet phases in interacting fermionic systems and their relation to chiral bosonic phases.
On the phenomenology of charged Higgs bosons in the complex MSSM
Energy Technology Data Exchange (ETDEWEB)
Thi Nhung Dao
2012-02-16
In this thesis, we study various decay and production processes of charged Higgs bosons at the Large Hadron Collider (LHC) in the context of a general complex Minimal Supersymmetric Standard Model (MSSM) with minimal flavor violation. We investigate the effect of the complex phases of the soft supersymmetry breaking parameters and of the Higgsino mixing parameter, {mu}, on the decay widths and production rates. The CP violating asymmetries induced by those phases are also considered. The calculations are done at the one-loop level. This is nontrivial since there are a large number of Feynman diagrams and various types of singularities (UV divergences, soft and collinear singularities, threshold singularities). We discuss in detail our calculation method and how to handle those divergences. In particular, the topic of one-loop renormalization and neutral-Higgs mixing effects in the complex MSSM for processes involving Higgs bosons are addressed. The higher order corrections to the decay of charged Higgs bosons into aW-boson and the lightest neutral Higgs boson are calculated and shown to be significantly large. The CP asymmetry arising from all complex phases is considered, especially from the top-quark trilinear coupling, A{sub t}, and {mu}, which induce a large contribution to the CP asymmetry. We perform a complete calculation of the next-to-leading order (NLO) electroweak (EW) corrections to the charged Higgs production in association with a W-boson via the bb annihilation channel and a consistent combination with other contributions including the standard and supersymmetric-QCD corrections and the gg fusion, with resummation of the leading radiative corrections to the bottom-Higgs couplings and the neutral Higgs-boson propagators. We observe a strong dependence of the production rates on the phases of A{sub t} and of the gluino-mass parameter M{sub 3} and a large CP asymmetry arising mainly from the gg fusion. The NLO EW corrections to the charged Higgs
Critical bubbles and fluctuations at the electroweak phase transition
Kripfganz, J; Schmidt, M G
1995-01-01
We discuss the critical bubbles of the electroweak phase transition using an effective high-temperature 3-dimensional action for the Higgs field \\varphi. The separate integration of gauge and Goldstone boson degrees of freedom is conveniently described in the 't Hooft-Feynman covariant background gauge. The effective dimensionless gauge coupling g_3(T)^2 in the broken phase is well behaved throughout the phase transition. However, the behavior of the one-loop Z(\\varphi) factors of the Higgs and gauge kinetic terms signalizes the breakdown of the derivative expansion and of the perturbative expansion for a range of small \\varphi values increasing with the Higgs mass m_H. Taking a functional S_z[\\varphi] with constant Z(\\varphi)=z instead of the full non-local effective action in some neighborhood of the saddlepoint we are calculating the critical bubbles for several temperatures. The fluctuation determinant is calculated to high accuracy using a variant of the heat kernel method. It gives a strong suppression ...
Phase Transitions in Definite Total Spin States of Two-Component Fermi Gases.
Yurovsky, Vladimir A
2017-05-19
Second-order phase transitions have no latent heat and are characterized by a change in symmetry. In addition to the conventional symmetric and antisymmetric states under permutations of bosons and fermions, mathematical group-representation theory allows for non-Abelian permutation symmetry. Such symmetry can be hidden in states with defined total spins of spinor gases, which can be formed in optical cavities. The present work shows that the symmetry reveals itself in spin-independent or coordinate-independent properties of these gases, namely as non-Abelian entropy in thermodynamic properties. In weakly interacting Fermi gases, two phases appear associated with fermionic and non-Abelian symmetry under permutations of particle states, respectively. The second-order transitions between the phases are characterized by discontinuities in specific heat. Unlike other phase transitions, the present ones are not caused by interactions and can appear even in ideal gases. Similar effects in Bose gases and strong interactions are discussed.
Kumar, S Santhosh; Shankaranarayanan, S
2017-11-17
In a bipartite set-up, the vacuum state of a free Bosonic scalar field is entangled in real space and satisfies the area-law- entanglement entropy scales linearly with area of the boundary between the two partitions. In this work, we show that the area law is violated in two spatial dimensional model Hamiltonian having dynamical critical exponent z = 3. The model physically corresponds to next-to-next-to-next nearest neighbour coupling terms on a lattice. The result reported here is the first of its kind of violation of area law in Bosonic systems in higher dimensions and signals the evidence of a quantum phase transition. We provide evidence for quantum phase transition both numerically and analytically using quantum Information tools like entanglement spectra, quantum fidelity, and gap in the energy spectra. We identify the cause for this transition due to the accumulation of large number of angular zero modes around the critical point which catalyses the change in the ground state wave function due to the next-to-next-to-next nearest neighbor coupling. Lastly, using Hubbard-Stratanovich transformation, we show that the effective Bosonic Hamiltonian can be obtained from an interacting fermionic theory and provide possible implications for condensed matter systems.
Charge density glass dynamics - Soft potentials and soft modes
Energy Technology Data Exchange (ETDEWEB)
Biljakovic, K., E-mail: katica@ifs.hr [Institute of Physics, HR-10001, Zagreb, P.O. Box 304 (Croatia); Staresinic, D., E-mail: damirs@ifs.hr [Institute of Physics, HR-10001, Zagreb, P.O. Box 304 (Croatia); Lasjaunias, J.C., E-mail: jean-claude.lasjaunias@pop3.grenoble.cnrs.fr [Institut Neel, CNRS, BP 166, F-38042, Grenoble, Cedex 9 (France); Remenyi, G., E-mail: Gyorgy.Remenyi@grenoble.cnrs.fr [Institut Neel, CNRS, BP 166, F-38042, Grenoble, Cedex 9 (France); Melin, R., E-mail: Regis.Melin@grenoble.cnrs.fr [Institut Neel, CNRS, BP 166, F-38042, Grenoble, Cedex 9 (France); Monceau, P., E-mail: pierre.monceau@grenoble.cnrs.fr [Institut Neel, CNRS, BP 166, F-38042, Grenoble, Cedex 9 (France); Sahling, S., E-mail: sven.olaf@gmail.com [Institut fuer Festkoerperphysik, Universitaet Dresden, D-01062, Dresden (Germany)
2012-06-01
An universal fingerprint of glasses has been found in low-temperature thermodynamic properties of charge/spin density wave (C/SDW) systems. Deviations from the well-known Debye, elastic continuum prediction for specific heat (flat C{sub p}/T{sup 3} plot) appear as two anomalies; the upturn below 1 K and a broad bump at T{approx}10 K (named Boson peak in glasses). The first one, inherent of localized two level systems within the shalow corrugated phase space, exhibits slow relaxation with the complex dynamics. The second one, 'Boson peak-like peak' was attributed to the pinned mode and incomplete softening of CDW superstructural mode. We discuss similar C{sub p}(T) features found also in incommensurate dielectrics with well documented soft-mode anomalies.
Scrutinizing the pion condensed phase
Energy Technology Data Exchange (ETDEWEB)
Carignano, Stefano; Mammarella, Andrea; Mannarelli, Massimo [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Lepori, Luca [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); Universita dell' Aquila, Dipartimento di Scienze Fisiche e Chimiche, Coppito-L' Aquila (Italy); Pagliaroli, Giulia [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Gran Sasso Science Institute, L' Aquila (Italy)
2017-02-15
When the isospin chemical potential exceeds the pion mass, charged pions condense in the zero-momentum state forming a superfluid. Chiral perturbation theory provides a very powerful tool for studying this phase. However, the formalism that is usually employed in this context does not clarify various aspects of the condensation mechanism and makes the identification of the soft modes problematic. We re-examine the pion condensed phase using different approaches within the chiral perturbation theory framework. As a first step, we perform a low-density expansion of the chiral Lagrangian valid close to the onset of the Bose-Einstein condensation. We obtain an effective theory that can be mapped to a Gross-Pitaevskii Lagrangian in which, remarkably, all the coefficients depend on the isospin chemical potential. The low-density expansion becomes unreliable deep in the pion condensed phase. For this reason, we develop an alternative field expansion deriving a low-energy Lagrangian analog to that of quantum magnets. By integrating out the ''radial'' fluctuations we obtain a soft Lagrangian in terms of the Nambu-Goldstone bosons arising from the breaking of the pion number symmetry. Finally, we test the robustness of the second-order transition between the normal and the pion condensed phase when next-to-leading-order chiral corrections are included. We determine the range of parameters for turning the second-order phase transition into a first-order one, finding that the currently accepted values of these corrections are unlikely to change the order of the phase transition. (orig.)
de Forges de Parny, L.; Rousseau, V. G.
2018-02-01
We study the quadratic Zeeman effect (QZE) in a system of antiferromagnetic spin-1 bosons on a square lattice and derive the ground-state phase diagrams by means of quantum Monte Carlo simulations and mean-field treatment. The QZE imbalances the populations of the magnetic sublevels σ =±1 and σ =0 , and therefore affects the magnetic and mobility properties of the phases. Both methods show that the tip of the even Mott lobes, stabilized by singlet state, is destroyed when turning on the QZE, thus leaving the space to the superfluid phase. Contrariwise, the tips of odd Mott lobes remain unaffected. Therefore, the Mott-superfluid transition with even filling strongly depends on the strength of the QZE, and we show that the QZE can act as a control parameter for this transition at fixed hopping. Using quantum Monte Carlo simulations, we elucidate the nature of the phase transitions and examine in detail the nematic order: the first-order Mott-superfluid transition with even filling observed in the absence of QZE becomes second order for weak QZE, in contradistinction to our mean-field results which predict a first-order transition in a larger range of QZE. Furthermore, a spin nematic order with director along the z axis is found in the odd Mott lobes and in the superfluid phase for energetically favored σ =±1 states. In the superfluid phase with even filling, the x y components of the nematic director remain finite only for moderate QZE.
Superfluid and insulating phases in an interacting-boson model: mean-field theory and the RPA
International Nuclear Information System (INIS)
Sheshadri, K.; Pandit, R.; Krishnamurthy, H.R.; Ramakrishnan, T.V.
1993-01-01
The bosonic Hubbard model is studied via a simple mean-field theory. At zero temperature, in addition to yielding a phase diagram that is qualitatively correct, namely a superfluid phase for non-integer fillings and a Mott transition from a superfluid to an insulating phase for integer fillings, this theory gives results that are in good agreement with Monte Carlo simulations. In particular, the superfluid fraction obtained as a function of the interaction strength U for both integer and non-integer fillings is close to the simulation results. In all phases the excitation spectra are obtained by using the random phase approximation (RPA): the spectrum has a gap in the insulating phase and is gapless (and linear at small wave vectors) in the superfluid phase. Analytic results are presented in the limits of large U and small superfluid density. Finite-temperature phase diagrams and the Mott-insulator-normal-phase crossover are also described. (orig.)
DEFF Research Database (Denmark)
Tichy, Malte C.; Bouvrier, P. Alexander; Mølmer, Klaus
2013-01-01
Composite bosons made of two bosonic constituents exhibit deviations from ideal bosonic behavior due to their substructure. This deviation is reflected by the normalization ratio of the quantum state of N composites. We find a set of saturable, efficiently evaluable bounds for this indicator, which...... quantifies the bosonic behavior of composites via the entanglement of their constituents. We predict an abrupt transition between ordinary and exaggerated bosonic behavior in a condensate of two-boson composites....
Vidas, Luciana; Günther, Christian M; Miller, Timothy A; Pfau, Bastian; Perez-Salinas, Daniel; Martínez, Elías; Schneider, Michael; Gührs, Erik; Gargiani, Pierluigi; Valvidares, Manuel; Marvel, Robert E; Hallman, Kent A; Haglund, Richard F; Eisebitt, Stefan; Wall, Simon
2018-05-18
We use resonant soft X-ray holography to image the insulator-metal phase transition in vanadium dioxide with element and polarization specificity and nanometer spatial resolution. We observe that nanoscale inhomogeneity in the film results in spatial-dependent transition pathways between the insulating and metallic states. Additional nanoscale phases form in the vicinity of defects which are not apparent in the initial or final states of the system, which would be missed in area-integrated X-ray absorption measurements. These intermediate phases are vital to understand the phase transition in VO 2 , and our results demonstrate how resonant imaging can be used to understand the electronic properties of phase-separated correlated materials obtained by X-ray absorption.
Heterogeneous shear elasticity of glasses: The origin of the boson peak
Marruzzo, Alessia
2013-03-08
The local elasticity of glasses is known to be inhomogeneous on a microscopic scale compared to that of crystalline materials. Their vibrational spectrum strongly deviates from that expected from Debye\\'s elasticity theory: The density of states deviates from Debye\\'s law, the sound velocity shows a negative dispersion in the boson-peak frequency regime and there is a strong increase of the sound attenuation near the boson-peak frequency. By comparing a mean-field theory of shear-elastic heterogeneity with a large-scale simulation of a soft-sphere glass we demonstrate that the observed anomalies in glasses are caused by elastic heterogeneity. By observing that the macroscopic bulk modulus is frequency independent we show that the boson-peak-related vibrational anomalies are predominantly due to the spatially fluctuating microscopic shear stresses. It is demonstrated that the boson-peak arises from the steep increase of the sound attenuation at a frequency which marks the transition from wave-like excitations to disorder-dominated ones.
Heterogeneous shear elasticity of glasses: The origin of the boson peak
Marruzzo, Alessia; Schirmacher, Walter; Fratalocchi, Andrea; Ruocco, Giancarlo
2013-01-01
The local elasticity of glasses is known to be inhomogeneous on a microscopic scale compared to that of crystalline materials. Their vibrational spectrum strongly deviates from that expected from Debye's elasticity theory: The density of states deviates from Debye's law, the sound velocity shows a negative dispersion in the boson-peak frequency regime and there is a strong increase of the sound attenuation near the boson-peak frequency. By comparing a mean-field theory of shear-elastic heterogeneity with a large-scale simulation of a soft-sphere glass we demonstrate that the observed anomalies in glasses are caused by elastic heterogeneity. By observing that the macroscopic bulk modulus is frequency independent we show that the boson-peak-related vibrational anomalies are predominantly due to the spatially fluctuating microscopic shear stresses. It is demonstrated that the boson-peak arises from the steep increase of the sound attenuation at a frequency which marks the transition from wave-like excitations to disorder-dominated ones.
Soft mode and magnetic phase transition in PrNi
International Nuclear Information System (INIS)
Alekseev, P.A.; Lazukov, V.N.; Sadikov, I.P.; Klement'ev, E.S.; Allenspach, P.; Chumlyakov, Yu.I.
2002-01-01
The spectrum of the magnetic excitation of the PrNi intermetallic compound monocrystal is studied through the neutrons inelastic scattering. Essential softening of certain collective modes of the magnetic excitation near the temperature of the ferromagnetic ordering T c ∼ 20 K is identified. The above result is analyzed from the viewpoint of the model, describing the magnetic phase transition in the systems with the directed magnetic moment [ru
Gravitational waves generated from the cosmological QCD phase transition within AdS/QCD
Directory of Open Access Journals (Sweden)
M. Ahmadvand
2017-09-01
Full Text Available We study the gravitational waves produced by the collision of the bubbles as a probe for the cosmological first order QCD phase transition, considering heavy static quarks. Using AdS/QCD and the correspondence between a first order Hawking–Page phase transition and confinement–deconfinement phase transition, we find the spectrum and the strain amplitude of the gravitational wave within the hard and soft wall models. We postulate the duration of the phase transition corresponds to the evaporation time of the black hole in the five dimensional dual gravity space, and thereby obtain a bound on the string length in the space and correspondingly on the duration of the QCD phase transition. We also show that IPTA and SKA detectors will be able to detect these gravitational waves, which can be an evidence for the first order deconfinement transition.
International Nuclear Information System (INIS)
Balbashov, A.M.; Berezin, A.G.; Gufan, Yu.M.; Kolyadko, G.S.; Marchukov, P.Yu.; Rudashevskij, E.G.
1987-01-01
A pronounced energy gap of a nonmagnetoelastic origin is observed experimentally in the spectrum of the low-frequency (quasiferromagnetic) antiferromagnetic resonance branch during a second order spin-flip phase transition in an external magnetic field directed along the a axis of the rhombic weak ferromagnetic YFeO 3 . From the theory developed which takes into account the susceptibility along the antiferromagnetism axis and dissipation processes, it follows that beside the usual AFMR oscillatory branches there should also be a relaxation mode which is ''soft'' fo the given transition. The magnitude of the energy gaps, the values of the kinetic coefficients, Dzyaloshinsky field strengths and ratio of the longitudinal susceptibility to the transverse susceptibility are determined by analyzing the experimental data obtained in fields up to 130 kOe in the frequency range from 60 to 400 GHz at room temperature
About the dynamics of structural phase transitions
International Nuclear Information System (INIS)
Medeiros, J.T.N.
1975-01-01
The dynamics of structural phase transitions with a fourth order interaction between the soft phonon fields is studied in the 1/n approximation, using many body methods at finite temperatures. Two limits are considered: high transition temperature T sub(c) (classical limit) and T sub(c) = 0 (quantum limit). The dynamical contribution to the critical coefficient eta of the correlation function is calculated in these limits. It is found that there is no dynamical contribution to eta in the classical limit, whereas in the quantum limit eta is non-zero only for dimensions of the system d [pt
Gravitational wave signals of electroweak phase transition triggered by dark matter
Energy Technology Data Exchange (ETDEWEB)
Chao, Wei [Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing, 100875 (China); Guo, Huai-Ke; Shu, Jing, E-mail: chaowei@bnu.edu.cn, E-mail: ghk@itp.ac.cn, E-mail: jshu@itp.ac.cn [CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China)
2017-09-01
We study in this work a scenario that the universe undergoes a two step phase transition with the first step happened to the dark matter sector and the second step being the transition between the dark matter and the electroweak vacuums, where the barrier between the two vacuums, that is necessary for a strongly first order electroweak phase transition (EWPT) as required by the electroweak baryogenesis mechanism, arises at the tree-level. We illustrate this idea by working with the standard model (SM) augmented by a scalar singlet dark matter and an extra scalar singlet which mixes with the SM Higgs boson. We study the conditions for such pattern of phase transition to occur and especially for the strongly first order EWPT to take place, as well as its compatibility with the basic requirements of a successful dark matter, such as observed relic density and constraints of direct detections. We further explore the discovery possibility of this pattern EWPT by searching for the gravitational waves generated during this process in spaced based interferometer, by showing a representative benchmark point of the parameter space that the generated gravitational waves fall within the sensitivity of eLISA, DECIGO and BBO.
Shen, H Z; Shao, X Q; Wang, G C; Zhao, X L; Yi, X X
2016-01-01
The quantum phase transition (QPT) describes a sudden qualitative change of the macroscopic properties mapped from the eigenspectrum of a quantum many-body system. It has been studied intensively in quantum systems with the spin-boson model, but it has barely been explored for systems in coupled spin-boson models. In this paper, we study the QPT with coupled spin-boson models consisting of coupled two-level atoms embedded in three-dimensional anisotropic photonic crystals. The dynamics of the system is derived exactly by means of the Laplace transform method, which has been proven to be equivalent to the dissipationless non-Markovian dynamics. Drawing on methods for analyzing the ground state, we obtain the phase diagrams through two exact critical equations and two QPTs are found: one QPT is that from the phase without one bound state to the phase with one bound state and another is that from one phase with the bound state having one eigenvalue to another phase where the bound state has two eigenvalues. Our analytical results also suggest a way of control to overcome the effect of decoherence by engineering the spectrum of the reservoirs to approach the non-Markovian regime and to form the bound state of the whole system for quantum devices and quantum statistics.
Photoinduced Topological Phase Transitions in Topological Magnon Insulators.
Owerre, S A
2018-03-13
Topological magnon insulators are the bosonic analogs of electronic topological insulators. They are manifested in magnetic materials with topologically nontrivial magnon bands as realized experimentally in a quasi-two-dimensional (quasi-2D) kagomé ferromagnet Cu(1-3, bdc), and they also possess protected magnon edge modes. These topological magnetic materials can transport heat as well as spin currents, hence they can be useful for spintronic applications. Moreover, as magnons are charge-neutral spin-1 bosonic quasiparticles with a magnetic dipole moment, topological magnon materials can also interact with electromagnetic fields through the Aharonov-Casher effect. In this report, we study photoinduced topological phase transitions in intrinsic topological magnon insulators in the kagomé ferromagnets. Using magnonic Floquet-Bloch theory, we show that by varying the light intensity, periodically driven intrinsic topological magnetic materials can be manipulated into different topological phases with different sign of the Berry curvatures and the thermal Hall conductivity. We further show that, under certain conditions, periodically driven gapped topological magnon insulators can also be tuned to synthetic gapless topological magnon semimetals with Dirac-Weyl magnon cones. We envision that this work will pave the way for interesting new potential practical applications in topological magnetic materials.
International Nuclear Information System (INIS)
Sachdev, S.
1999-01-01
Phase transitions are normally associated with changes of temperature but a new type of transition - caused by quantum fluctuations near absolute zero - is possible, and can tell us more about the properties of a wide range of systems in condensed-matter physics. Nature abounds with phase transitions. The boiling and freezing of water are everyday examples of phase transitions, as are more exotic processes such as superconductivity and superfluidity. The universe itself is thought to have passed through several phase transitions as the high-temperature plasma formed by the big bang cooled to form the world as we know it today. Phase transitions are traditionally classified as first or second order. In first-order transitions the two phases co-exist at the transition temperature - e.g. ice and water at 0 deg., or water and steam at 100 deg. In second-order transitions the two phases do not co-exist. In the last decade, attention has focused on phase transitions that are qualitatively different from the examples noted above: these are quantum phase transitions and they occur only at the absolute zero of temperature. The transition takes place at the ''quantum critical'' value of some other parameter such as pressure, composition or magnetic field strength. A quantum phase transition takes place when co-operative ordering of the system disappears, but this loss of order is driven solely by the quantum fluctuations demanded by Heisenberg's uncertainty principle. The physical properties of these quantum fluctuations are quite distinct from those of the thermal fluctuations responsible for traditional, finite-temperature phase transitions. In particular, the quantum system is described by a complex-valued wavefunction, and the dynamics of its phase near the quantum critical point requires novel theories that have no analogue in the traditional framework of phase transitions. In this article the author describes the history of quantum phase transitions. (UK)
Gravitationally compact objects as nucleation sites for first-order vacuum phase transitions
International Nuclear Information System (INIS)
Samuel, D.A.; Hiscock, W.A.
1992-01-01
A characteristic of first-order phase transitions is their ability to be initiated by nucleation sites. In this paper we consider the role that gravitationally compact objects may play as nucleation sites for first-order phase transitions within quantum fields. As the presence of nucleation sites may prevent the onset of supercooling, the existence of nucleation sites for phase transitions within quantum fields may play an important role in some inflationary models of the Universe, in which the Universe is required to exist in a supercooled state for a period of time. In this paper we calculate the Euclidean action for an O(3) bubble nucleating about a gravitationally compact object, taken to be a boson star for simplicity. The gravitational field of the boson star is taken to be a small perturbation on flat space, and the O(3) action is calculated to linear order as a perturbation on the O(4) action. The Euclidean bubble profile is found by solving the (Higgs) scalar field equation numerically; the thin-wall approximation is not used. The gravitationally compact objects are found to have the effect of reducing the Euclidean action of the nucleating bubble, as compared to the Euclidean action for the bubble in flat spacetime. The effect is strongest when the size of the gravitationally compact object is comparable to the size of the nucleating bubble. Further, the size of the decrease in action increases as the nucleating ''star'' is made more gravitationally compact. Thus, gravitationally compact objects may play the role of nucleation sites. However, their importance to the process of false-vacuum decay is strongly dependent upon their number density within the Universe
K factor for Higgs boson production via gluon fusion process at hadron colliders
International Nuclear Information System (INIS)
Tanaka, H.
1992-01-01
In this paper soft gluon corrections for Higgs boson production at hadron colliders are calculated. It is found that the soft contributions for the Higgs boson production via gluon fusion process is large and it cannot be neglected even at SSC energy. Some qualitative discussions for the QCD corrections to the Higgs boson production at hadron colliders and their background processes are presented for various Higgs boson mass cases
Huh, Joonsuk; Yung, Man-Hong
2017-08-07
Molecular vibroic spectroscopy, where the transitions involve non-trivial Bosonic correlation due to the Duschinsky Rotation, is strongly believed to be in a similar complexity class as Boson Sampling. At finite temperature, the problem is represented as a Boson Sampling experiment with correlated Gaussian input states. This molecular problem with temperature effect is intimately related to the various versions of Boson Sampling sharing the similar computational complexity. Here we provide a full description to this relation in the context of Gaussian Boson Sampling. We find a hierarchical structure, which illustrates the relationship among various Boson Sampling schemes. Specifically, we show that every instance of Gaussian Boson Sampling with an initial correlation can be simulated by an instance of Gaussian Boson Sampling without initial correlation, with only a polynomial overhead. Since every Gaussian state is associated with a thermal state, our result implies that every sampling problem in molecular vibronic transitions, at any temperature, can be simulated by Gaussian Boson Sampling associated with a product of vacuum modes. We refer such a generalized Gaussian Boson Sampling motivated by the molecular sampling problem as Vibronic Boson Sampling.
Xu, Cenke
Several examples of quantum spin systems and pseudo spin systems have been studied, and unconventional states of matters and phase transitions have been realized in all these systems under consideration. In the p +/- ip superconductor Josephson lattice and the p--band cold atomic system trapped in optical lattices, novel phases which behave similarly to 1+1 dimensional systems are realized, despite the fact that the real physical systems are in two or three dimensional spaces. For instance, by employing a spin-wave analysis together with a new duality transformation, we establish the existence and stability of a novel gapless "critical phase", which we refer to as a "bond algebraic liquid". This novel critical phase is analogous to the 1+1 dimensional algebraic boson liquid phase. The reason for the novel physics is that there is a quasilocal gauge symmetry in the effective low energy Hamiltonian. In a spin-1 system on the kagome lattice, and a hard-core boson system on the honeycomb lattice, the low energy physics is controlled by two components of compact U(1) gauge symmetries that emerge at low energy. Making use of the confinement nature of the 2+1 dimensional compact gauge theories and the powerful duality between gauge theories and height field theories, the crystalline phase diagrams are studied for both systems, and the transitions to other phases are also considered. These phase diagrams might be accessible in strongly correlated materials, or atomic systems in optical lattices. A novel quantum ground state of matter is realized in a bosonic model on three dimensional fcc lattice with emergent low energy excitations. The novel phase obtained is a stable gapless boson liquid phase, with algebraic boson density correlations. The stability of this phase is protected against the instanton effect and superfluidity by self-duality and large gauge symmetries on both sides of the duality. The gapless collective excitations of this phase closely resemble the
Pattern Transitions in a Soft Cylindrical Shell
Yang, Yifan; Dai, Hui-Hui; Xu, Fan; Potier-Ferry, Michel
2018-05-01
Instability patterns of rolling up a sleeve appear more intricate than the ones of walking over a rug on floor, both characterized as systems of uniaxially compressed soft film on stiff substrate. This can be explained by curvature effects. To investigate pattern transitions on a curved surface, we study a soft shell sliding on a rigid cylinder by experiments, computations and theoretical analyses. We reveal a novel postbuckling phenomenon involving multiple successive bifurcations: smooth-wrinkle-ridge-sagging transitions. The shell initially buckles into periodic axisymmetric wrinkles at the threshold and then a wrinkle-to-ridge transition occurs upon further axial compression. When the load increases to the third bifurcation, the amplitude of the ridge reaches its limit and the symmetry is broken with the ridge sagging into a recumbent fold. It is identified that hysteresis loops and the Maxwell equal-energy conditions are associated with the coexistence of wrinkle-ridge or ridge-sagging patterns. Such a bifurcation scenario is inherently general and independent of material constitutive models.
Soft-mode transition in the ferroelastic crystal K2Hg(CN)4
International Nuclear Information System (INIS)
Powell, B.M.; Gerlach, P.N.
1989-01-01
Inelastic neutron scattering techniques have been used to investigate the structural transition from the paraelastic to the ferroelastic phase in K 2 Hg(CN) 4 . Several low-frequency phonon branches were measured along the high-symmetry directions and found to be almost independent of temperature. However, a particular low-lying branch along [111] was found to show a strong temperature dependence. The structure factor for this mode shows it to be a longitudinal, librational mode whose eigenvector specifies antiphase rotation of adjacent rigid cyanotetrahedra. This is in agreement with the change in the crystal structure observed at the transition by diffraction measurements. The frequency of this branch at the zone- boundary L point tended to zero at ∼101 K, thus showing the paraelastic to ferroelastic transition in this cyanospinel is a soft-mode transition. (author)
Zhao, Bo
Phase transitions are one of the most exciting physical phenomena ever discovered. The understanding of phase transitions has long been of interest. Recently eigenstate phase transitions have been discovered and studied; they are drastically different from traditional thermal phase transitions. In eigenstate phase transitions, a sharp change is exhibited in properties of the many-body eigenstates of the Hamiltonian of a quantum system, but not the thermal equilibrium properties of the same system. In this thesis, we study two different types of eigenstate phase transitions. The first is the eigenstate phase transition within the ferromagnetic phase of an infinite-range spin model. By studying the interplay of the eigenstate thermalization hypothesis and Ising symmetry breaking, we find two eigenstate phase transitions within the ferromagnetic phase: In the lowest-temperature phase the magnetization can macroscopically oscillate by quantum tunneling between up and down. The relaxation of the magnetization is always overdamped in the remainder of the ferromagnetic phase, which is further divided into phases where the system thermally activates itself over the barrier between the up and down states, and where it quantum tunnels. The second is the many-body localization phase transition. The eigenstates on one side of the transition obey the eigenstate thermalization hypothesis; the eigenstates on the other side are many-body localized, and thus thermal equilibrium need not be achieved for an initial state even after evolving for an arbitrary long time. We study this many-body localization phase transition in the strong disorder renormalization group framework. After setting up a set of coarse-graining rules for a general one dimensional chain, we get a simple "toy model'' and obtain an almost purely analytical solution to the infinite-randomness critical fixed point renormalization group equation. We also get an estimate of the correlation length critical exponent nu
Phase controlled metal–insulator transition in multi-leg quasiperiodic optical lattices
International Nuclear Information System (INIS)
Maiti, Santanu K.; Sil, Shreekantha; Chakrabarti, Arunava
2017-01-01
A tight-binding model of a multi-leg ladder network with a continuous quasiperiodic modulation in both the site potential and the inter-arm hopping integral is considered. The model mimics optical lattices where ultra-cold fermionic or bosonic atoms are trapped in double well potentials. It is observed that, the relative phase difference between the on-site potential and the inter-arm hopping integral, which can be controlled by the tuning of the interfering laser beams trapping the cold atoms, can result in a mixed spectrum of one or more absolutely continuous subband(s) and point like spectral measures. This opens up the possibility of a re-entrant metal–insulator transition. The subtle role played by the relative phase difference mentioned above is revealed, and we corroborate it numerically by working out the multi-channel electronic transmission for finite two-, and three-leg ladder networks. The extension of the calculation beyond the two-leg case is trivial, and is discussed in the work. - Graphical abstract: ▪ - Highlights: • Phase controlled metal–insulator transition is discussed. • An analytical prescription is given to understand MI transition. • Our work provides a way of designing experiments involving laser beams.
Activity induced phase transition in mixtures of active and passive agents
Sinha Mahapatra, Pallab; Kulkarni, Ajinkya
2017-11-01
Collective behaviors of self-propelling agents are ubiquitous in nature that produces interesting patterns. The objective of this study is to investigate the phase transition in mixtures of active and inert agents suspended in a liquid. A modified version of the Vicsek Model has been used (see Ref.), where the particles are modeled as soft disks with finite mass, confined in a square domain. The particles are required to align their local motion to their immediate neighborhood, similar to the Vicsek model. We identified the transition from disorganized thermal-like motion to an organized vortical motion. We analyzed the nature of the transition by using different order parameters. Furthermore the switching between the phases has been investigated via artificial nucleation of randomly picked active agents spanning the entire domain. Finally the motivation for this phase transition has been explained via average dissipation and the mean square displacement (MSD) of the agents.
Phase transitions and pairing signature in strongly attractive Fermi atomic gases
International Nuclear Information System (INIS)
Guan, X. W.; Bortz, M.; Batchelor, M. T.; Lee, C.
2007-01-01
We investigate pairing and quantum phase transitions in the one-dimensional two-component Fermi atomic gas in an external field. The phase diagram, critical fields, magnetization, and local pairing correlation are obtained analytically via the exact thermodynamic Bethe ansatz solution. At zero temperature, bound pairs of fermions with opposite spin states form a singlet ground state when the external field H c1 . A completely ferromagnetic phase without pairing occurs when the external field H>H c2 . In the region H c1 c2 , we observe a mixed phase of matter in which paired and unpaired atoms coexist. The phase diagram is reminiscent of that of type II superconductors. For temperatures below the degenerate temperature and in the absence of an external field, the bound pairs of fermions form hard-core bosons obeying generalized exclusion statistics
Density-functional theory for fluid-solid and solid-solid phase transitions.
Bharadwaj, Atul S; Singh, Yashwant
2017-03-01
We develop a theory to describe solid-solid phase transitions. The density functional formalism of classical statistical mechanics is used to find an exact expression for the difference in the grand thermodynamic potentials of the two coexisting phases. The expression involves both the symmetry conserving and the symmetry broken parts of the direct pair correlation function. The theory is used to calculate phase diagram of systems of soft spheres interacting via inverse power potentials u(r)=ε(σ/r)^{n}, where parameter n measures softness of the potential. We find that for 1/nfcc) structure while for 1/n≥0.154 the body-centred-cubic (bcc) structure is preferred. The bcc structure transforms into the fcc structure upon increasing the density. The calculated phase diagram is in good agreement with the one found from molecular simulations.
Sole, Ricard V; Solé, Ricard V; SolÃ©, Ricard V; Sol, Ricard V; Solé, Ricard V
2011-01-01
Phase transitions--changes between different states of organization in a complex system--have long helped to explain physics concepts, such as why water freezes into a solid or boils to become a gas. How might phase transitions shed light on important problems in biological and ecological complex systems? Exploring the origins and implications of sudden changes in nature and society, Phase Transitions examines different dynamical behaviors in a broad range of complex systems. Using a compelling set of examples, from gene networks and ant colonies to human language and the degradation of diverse ecosystems, the book illustrates the power of simple models to reveal how phase transitions occur. Introductory chapters provide the critical concepts and the simplest mathematical techniques required to study phase transitions. In a series of example-driven chapters, Ricard Solé shows how such concepts and techniques can be applied to the analysis and prediction of complex system behavior, including the origins of ...
Diffraction as a CP and lineshape analyzer for MSSM Higgs bosons at the CERN LHC
International Nuclear Information System (INIS)
Ellis, John; Lee, Jae Sik; Pilaftsis, Apostolos
2005-01-01
We study the production and decay of a coupled system of mixed neutral minimal supersymmetric extension of the Standard Model (MSSM) Higgs bosons in exclusive double-diffractive processes at the LHC, including nonvanishing CP phases in the soft supersymmetry-breaking gaugino masses and third-generation trilinear squark couplings. The three neutral Higgs bosons are naturally nearly degenerate, for large values of tanβ, when the charged Higgs boson weighs around 150 GeV. Large mixing between all three neutral Higgs bosons is possible when CP is violated, a threeway mixing scenario which we also term trimixing. A resolution in the Higgs mass of ∼1 GeV, which may be achievable using the missing-mass method, would allow one to distinguish nearly degenerate Higgs bosons by studying the production lineshape. Measurements of the polarizations of the tau leptons coming from the Higgs-boson decays could offer a direct and observable signal of CP violation in the Higgs sector
Superfluid/Bose-glass transition in one dimension
Ristivojevic, Zoran; Petković, Aleksandra; Le Doussal, Pierre; Giamarchi, Thierry
2014-09-01
We consider a one-dimensional system of interacting bosons in a random potential. At zero temperature, it can be either in the superfluid or in the insulating phase. We study the transition at weak disorder and moderate interaction. Using a systematic approach, we derive the renormalization group equations at two-loop order and discuss the phase diagram. We find the universal form of the correlation functions at the transitions and compute the logarithmic corrections to the main universal power-law behavior. In order to mimic large density fluctuations on a single site, we study a simplified model of disordered two-leg bosonic ladders with correlated disorder across the rung. Contrarily to the single-chain case, the latter system exhibits a transition between a superfluid and a localized phase where the exponents of the correlation functions at the transition do not take universal values.
International Nuclear Information System (INIS)
Lee, J. Y.; Guan, X. W.; Batchelor, M. T.; Lee, C.
2009-01-01
We investigate magnetism and quantum phase transitions in a one-dimensional system of integrable spin-1 bosons with strongly repulsive density-density interaction and antiferromagnetic spin-exchange interaction via the thermodynamic Bethe ansatz method. At zero temperature, the system exhibits three quantum phases: (i) a singlet phase of boson pairs when the external magnetic field H is less than the lower critical field H c1 ; (ii) a ferromagnetic phase of atoms in the hyperfine state |F=1, m F =1> when the external magnetic field exceeds the upper critical field H c2 ; and (iii) a mixed phase of singlet pairs and unpaired atoms in the intermediate region H c1 c2 . At finite temperatures, the spin fluctuations affect the thermodynamics of the model through coupling the spin bound states to the dressed energy for the unpaired m F =1 bosons. However, such spin dynamics is suppressed by a sufficiently strong external field at low temperatures. Thus the singlet pairs and unpaired bosons may form a two-component Luttinger liquid in the strong coupling regime.
Energy Technology Data Exchange (ETDEWEB)
Cai, Guojun; Li, Changsheng, E-mail: lics@ral.neu.edu.cn; Cai, Ban; Wang, Qiwen
2017-05-15
Fe–6.5 wt%Si electrical steel characterized with excellent soft magnetic properties such as almost zero magnetostriction, low eddy current and hysteresis losses characteristics has been widely applied in high frequency fields. In this work, the role of texture evolution and ordered phase transition in soft magnetic properties of annealed sheets was explored using EBSD, XRD and TEM. The results demonstrate that accompanied with the increase of annealing temperatures, an increase on the B8 is attributable to a contribution combining the sizes of recrystallization grains with APBs of ordered phases as pinning the migration of magnetic domain wall. Whereas B50 declines to a minimum value (1.479 T) and then increases to a certain value (1.695 T) due to different types and intensities of textures affecting on the magnetocrystalline anisotropy energy. Meanwhile, the dislocation density gradually decreases and corresponding to a gradual decline in the internal stress, which makes the coercive force (H{sub c}) decrease monotonically. - Highlights: • Role of texture and ordered phase in Fe–6.5 wt%Si were studied. • With increasing annealing temperatures, H{sub c} decreases monotonically. • Combining grain sizes with APBs in B8 measurements. • Increasing annealing temperatures, B50 declines and then increases due to texture.
The QCD phase transition. From the microscopic mechanism to signals
International Nuclear Information System (INIS)
Shuryak, E.V.
1997-01-01
This talk consists of two very different parts: the first one deals with non-perturbative QCD and physics of the chiral restoration, the second with rather low-key (and still unfinished) work aiming at obtaining EOS and other properties of hot/dense hadronic matter from data on heavy ion collisions. The microscopic mechanism for chiral restoration phase transition is a transition from randomly placed tunneling events (instantons) at low T to a set of strongly correlated tunneling-anti-tunneling events (known as instanton-anti-instanton molecules) at high T. Many features of the transition can be explained in this simple picture, especially the critical line and its dependence on quark masses. This scenario predicts qualitative change of the basic quark-quark interactions around the phase transition line, with some states (such as pion-sigma ones) probably surviving event at T > T c . In the second half of the talk experimental data on collective flow in heavy ion collision are discussed its hydro-based description and relation to equation of state (EOS). A distinct feature of the QCD phase transition region is high degree of 'softness', (small ratio pressure/energy density). (author)
Soft modes and phase transition at 74K in Rb2ZnCl4
International Nuclear Information System (INIS)
Mashiyama, Hiroyuki; Sugimoto, Kousirou; Oohara, Yasuaki; Yoshizawa, Hideki.
1993-01-01
The orthorhombic to monoclinic transition at T m = 73.5K in Rb 2 ZnCl 4 is investigated by means of neutron scattering at JRR-3M. The superlattice reflections observed below T m increases as (T m - T) 2β with β = 0.38. The dispersion relations of low energy are determined both above and below T m . The softening of phonon frequency is observed around the Brillouin zone-boundary. The square of the energy transfer of the soft phonon obeys a linear relation on temperature. (author)
Decays of Higgs bosons to bb-bar, ττ-bar, and cc-bar as signatures of supersymmetry and CP phases
International Nuclear Information System (INIS)
Ibrahim, Tarek; Nath, Pran
2003-01-01
The branching ratio of the lightest Higgs boson decay into bb(bar sign), ττ-bar and cc-bar is sensitive to supersymmetric effects. We include in this work the effects of CP phases on the Higgs boson decays. Specifically we compute the deviation of the CP phase dependent branching ratio from the standard model result. The analysis includes the full one loop corrections of fermion masses including CP phases involving the gluino, the chargino and the neutralino exchanges. The analysis shows that the supersymmetric effects with CP phases can change the branching ratios by as much as 100% for the lightest Higgs boson decay into bb(bar sign) and ττ-bar with similar results holding for the heavier Higgs boson decays. A detailed analysis is also given for the effects of CP phases on the Higgs boson decays into cc-bar. The deviations of R b/τ and R b/c from the standard model result are investigated as a possible signature of supersymmetry and CP effects. Thus a measurement of the decays of the Higgs boson into bb-bar, ττ-bar and cc-bar may provide important clues regarding the existence of supersymmetry and CP phases
Energy Technology Data Exchange (ETDEWEB)
Huse, Nils; Cho, Hana; Hong, Kiryong; Jamula, Lindsey; de Groot, Frank M. F.; Kim, Tae Kyu; McCusker, James K.; Schoenlein, Robert W.
2011-04-21
We present the first implementation of femtosecond soft X-ray spectroscopy as an ultrafast direct probe of the excited-state valence orbitals in solution-phase molecules. This method is applied to photoinduced spin crossover of [Fe(tren(py)3)]2+, where the ultrafast spinstate conversion of the metal ion, initiated by metal-to-ligand charge-transfer excitation, is directly measured using the intrinsic spin-state selectivity of the soft X-ray L-edge transitions. Our results provide important experimental data concerning the mechanism of ultrafast spin-state conversion and subsequent electronic and structural dynamics, highlighting the potential of this technique to study ultrafast phenomena in the solution phase.
International Nuclear Information System (INIS)
Kapitonov, V.S.
1991-01-01
This paper offers a formulation of mean-field theory for the Hubbard model that is different from the one developed in the work of Anderson. The modified slave-boson method is used. The advantage of the method is that it is not necessary to exclude doubly occupied sites by using the approximately canonical transformation. In the proposed theory, Cooper pairs and the energy gap are a result of the condensation of the slave Bose field that describes doubly occupied sites. Here, the modified slave-boson method is used to describe the metal-insulator and metal-superconductor phase transitions in the Hubbard model. Expressions are derived for the energy gap and phase-transition temperature
Cosmological phase transitions
International Nuclear Information System (INIS)
Kolb, E.W.
1993-10-01
If modern ideas about the role of spontaneous symmetry breaking in fundamental physics are correct, then the Universe should have undergone a series of phase transitions early in its history. The study of cosmological phase transitions has become an important aspect of early-Universe cosmology. In this lecture I review some very recent work on three aspects of phase transitions: the electroweak transition, texture, and axions
Phase space and jet definitions in soft-collinear effective theory
International Nuclear Information System (INIS)
Cheung, William Man-Yin; Luke, Michael; Zuberi, Saba
2009-01-01
We discuss consistent power counting for integrating soft and collinear degrees of freedom over arbitrary regions of phase space in the soft-collinear effective theory, and illustrate our results at one-loop with several jet algorithms: JADE, Sterman-Weinberg and k perpendicular . Consistently applying soft-collinear effective theory power counting in phase space, along with nontrivial zero-bin subtractions, prevents double counting of final states. The resulting phase space integrals over soft and collinear regions are individually ultraviolet divergent, but the phase space ultraviolet divergences cancel in the sum. Whether the soft and collinear contributions are individually infrared safe depends on the jet definition. We show that while this is true at one-loop for JADE and Sterman-Weinberg, the k perpendicular algorithm does not factorize into individually infrared safe soft and collinear pieces in dimensional regularization. We point out that this statement depends on the ultraviolet regulator, and that in a cutoff scheme the soft functions are infrared safe.
Metastability at the Yield-Stress Transition in Soft Glasses
Directory of Open Access Journals (Sweden)
Matteo Lulli
2018-05-01
Full Text Available We study the solid-to-liquid transition in a two-dimensional fully periodic soft-glassy model with an imposed spatially heterogeneous stress. The model we consider consists of droplets of a dispersed phase jammed together in a continuous phase. When the peak value of the stress gets close to the yield stress of the material, we find that the whole system intermittently tunnels to a metastable “fluidized” state, which relaxes back to a metastable “solid” state by means of an elastic-wave dissipation. This macroscopic scenario is studied through the microscopic displacement field of the droplets, whose time statistics displays a remarkable bimodality. Metastability is rooted in the existence, in a given stress range, of two distinct stable rheological branches, as well as long-range correlations (e.g., large dynamic heterogeneity developed in the system. Finally, we show that a similar behavior holds for a pressure-driven flow, thus suggesting possible experimental tests.
Metastability at the Yield-Stress Transition in Soft Glasses
Lulli, Matteo; Benzi, Roberto; Sbragaglia, Mauro
2018-04-01
We study the solid-to-liquid transition in a two-dimensional fully periodic soft-glassy model with an imposed spatially heterogeneous stress. The model we consider consists of droplets of a dispersed phase jammed together in a continuous phase. When the peak value of the stress gets close to the yield stress of the material, we find that the whole system intermittently tunnels to a metastable "fluidized" state, which relaxes back to a metastable "solid" state by means of an elastic-wave dissipation. This macroscopic scenario is studied through the microscopic displacement field of the droplets, whose time statistics displays a remarkable bimodality. Metastability is rooted in the existence, in a given stress range, of two distinct stable rheological branches, as well as long-range correlations (e.g., large dynamic heterogeneity) developed in the system. Finally, we show that a similar behavior holds for a pressure-driven flow, thus suggesting possible experimental tests.
Superconductivity in mixed boson-fermion systems
International Nuclear Information System (INIS)
Ioffe, L.; Larkin, A.I.; Ovchinnikov, Yu.N.; Yu, L.
1989-12-01
The superconductivity of mixed boson-fermion systems is studied using a simple boson-fermion transformation model. The critical temperature of the superconducting transition is calculated over a wide range of the narrow boson band position relative to the Fermi level. The BCS scenario and boson condensation picture are recovered in two limiting cases of high and low positions of boson band, respectively, with modifications due to boson-fermion interaction. (author). 11 refs
Interaction effects and quantum phase transitions in topological insulators
International Nuclear Information System (INIS)
Varney, Christopher N.; Sun Kai; Galitski, Victor; Rigol, Marcos
2010-01-01
We study strong correlation effects in topological insulators via the Lanczos algorithm, which we utilize to calculate the exact many-particle ground-state wave function and its topological properties. We analyze the simple, noninteracting Haldane model on a honeycomb lattice with known topological properties and demonstrate that these properties are already evident in small clusters. Next, we consider interacting fermions by introducing repulsive nearest-neighbor interactions. A first-order quantum phase transition was discovered at finite interaction strength between the topological band insulator and a topologically trivial Mott insulating phase by use of the fidelity metric and the charge-density-wave structure factor. We construct the phase diagram at T=0 as a function of the interaction strength and the complex phase for the next-nearest-neighbor hoppings. Finally, we consider the Haldane model with interacting hard-core bosons, where no evidence for a topological phase is observed. An important general conclusion of our work is that despite the intrinsic nonlocality of topological phases their key topological properties manifest themselves already in small systems and therefore can be studied numerically via exact diagonalization and observed experimentally, e.g., with trapped ions and cold atoms in optical lattices.
Lima, L. S.
2017-06-01
We use the SU(3) Schwinger boson theory to study the spin transport properties of the two-dimensional anisotropic frustrated Heisenberg model in a honeycomb lattice at T = 0 with single ion anisotropy and third neighbor interactions. We have investigated the behavior of the spin conductivity for this model that presents exchange interactions J1 , J2 and J3 . We study the spin transport in the Bose-Einstein condensation regime where the bosons tz are condensed. Our results show an influence of the quantum phase transition point on the spin conductivity behavior. We also have made a diagrammatic expansion for the Green-function and did not obtain any significant change of the results.
Electroweak phase transition in the economical 3-3-1 model
Energy Technology Data Exchange (ETDEWEB)
Phong, Vo Quoc; Van, Vo Thanh; Minh, Le Hoang [Ho Chi Minh City University of Science, Department of Theoretical Physics, Ho Chi Minh City (Viet Nam); Long, Hoang Ngoc [Vietnamese Academy of Science and Technology, Institute of Physics, Hanoi (Viet Nam)
2015-07-15
We consider the EWPT in the economical 3-3-1 (E331) model. Our analysis shows that the EWPT in the model is a sequence of two first-order phase transitions, SU(3) → SU(2) at the TeV scale and SU(2) → U(1) at the 100 GeV scale. The EWPT SU(3) → SU(2) is triggered by the new bosons and the exotic quarks; its strength is about 1-13 if the mass ranges of these new particles are 10{sup 2}-10{sup 3} GeV. The EWPT SU(2) → U(1) is strengthened by only the new bosons; its strength is about 1-1.15 if the mass parts of H{sub 1}{sup 0}, H{sub 2}{sup ±} and Y{sup ±} are in the ranges 10-10{sup 2} GeV. The contributions of H{sub 1}{sup 0} and H{sub 2}{sup ±} to the strengths of both EWPTs may make them sufficiently strong to provide large deviations from thermal equilibrium and B violation necessary for baryogenesis. (orig.)
X-boson cumulant approach to the topological Kondo insulators
Ramos, E.; Franco, R.; Silva-Valencia, J.; Foglio, M. E.; Figueira, M. S.
2014-12-01
In this work we present a generalization of our previous work of the X-boson approach to the periodic Anderson model (PAM), adequate to study a novel class of intermetallic 4f and 5f orbitals materials: the topological Kondo insulators, whose paradigmatic material is the compound SmB6. For simplicity, we consider a version of the PAM on a 2D square lattice, adequate to describe Ce-based compounds in two dimensions. The starting point of the model is the 4f - Ce ions orbitals, with J = 5/2 multiplet, in the presence of spin-orbit coupling. Our technique works well for all of the parameters of the model and avoids the unwanted phase transitions of the slave boson mean field theory. We present a critical comparison of our results with those of the usual slave boson method, that has been intensively used to describe this class of materials. We also obtain a new valence first order transition which we attribute to the vec k dependence of the hybridization.
Cosmological phase transitions
International Nuclear Information System (INIS)
Kolb, E.W.
1987-01-01
If the universe stated from conditions of high temperature and density, there should have been a series of phase transitions associated with spontaneous symmetry breaking. The cosmological phase transitions could have observable consequences in the present Universe. Some of the consequences including the formation of topological defects and cosmological inflation are reviewed here. One of the most important tools in building particle physics models is the use of spontaneous symmetry breaking (SSB). The proposal that there are underlying symmetries of nature that are not manifest in the vacuum is a crucial link in the unification of forces. Of particular interest for cosmology is the expectation that are the high temperatures of the big bang symmetries broken today will be restored, and that there are phase transitions to the broken state. The possibility that topological defects will be produced in the transition is the subject of this section. The possibility that the Universe will undergo inflation in a phase transition will be the subject of the next section. Before discussing the creation of topological defects in the phase transition, some general aspects of high-temperature restoration of symmetry and the development of the phase transition will be reviewed. 29 references, 1 figure, 1 table
Structural and phase transitions of one and two polymer mushrooms in poor solvent
Yang, Delian; Wang, Qiang
2014-05-01
Using the recently proposed fast lattice Monte Carlo (FLMC) simulations and the corresponding lattice self-consistent field (LSCF) calculations based on the same model system, where multiple occupancy of lattice sites is allowed [Q. Wang, Soft Matter 5, 4564 (2009); Q. Wang, Soft Matter 5, 6206 (2010)], we studied the coil-globule transition (CGT) of one-mushroom systems and the fused-separated transition (FST) of two-mushroom systems, where a polymer mushroom is formed by a group of n homopolymer chains each of N segments end-grafted at the same point onto a flat substrate and immersed in a poor solvent. With our soft potential that allows complete particle overlapping, LSCF theory neglecting the system fluctuations/correlations becomes exact in the limit of n → ∞, and FLMC results approach LSCF predictions with increasing n. Using LSCF calculations, we systematically constructed the phase diagrams of one- and two-mushroom systems. A second-order symmetric-asymmetric transition (SAT) was found in the globule state of one-mushroom systems, where the rotational symmetry around the substrate normal passing through the grafting point is broken in each individual configuration but preserved by the degeneracy of different orientations of these asymmetric configurations. Three different states were also found in two-mushroom systems: separated coils, separated globules, and fused globule. We further studied the coupling between FST in two-mushroom systems and CGT and SAT of each mushroom. Finally, direct comparisons between our simulation and theoretical results, without any parameter-fitting, unambiguously and quantitatively revealed the fluctuation/correlation effects on these phase transitions.
The electroweak phase transition in minimal supergravity models
Nanopoulos, Dimitri V
1994-01-01
We have explored the electroweak phase transition in minimal supergravity models by extending previous analysis of the one-loop Higgs potential to include finite temperature effects. Minimal supergravity is characterized by two higgs doublets at the electroweak scale, gauge coupling unification, and universal soft-SUSY breaking at the unification scale. We have searched for the allowed parameter space that avoids washout of baryon number via unsuppressed anomalous Electroweak sphaleron processes after the phase transition. This requirement imposes strong constraints on the Higgs sector. With respect to weak scale baryogenesis, we find that the generic MSSM is {\\it not} phenomenologically acceptable, and show that the additional experimental and consistency constraints of minimal supergravity restricts the mass of the lightest CP-even Higgs even further to $m_h\\lsim 32\\GeV$ (at one loop), also in conflict with experiment. Thus, if supergravity is to allow for baryogenesis via any other mechanism above the weak...
Diffeomorphisms as symplectomorphisms in history phase space: Bosonic string model
International Nuclear Information System (INIS)
Kouletsis, I.; Kuchar, K.V.
2002-01-01
The structure of the history phase space G of a covariant field system and its history group (in the sense of Isham and Linden) is analyzed on an example of a bosonic string. The history space G includes the time map T from the spacetime manifold (the two-sheet) Y to a one-dimensional time manifold T as one of its configuration variables. A canonical history action is posited on G such that its restriction to the configuration history space yields the familiar Polyakov action. The standard Dirac-ADM action is shown to be identical with the canonical history action, the only difference being that the underlying action is expressed in two different coordinate charts on G. The canonical history action encompasses all individual Dirac-ADM actions corresponding to different choices T of foliating Y. The history Poisson brackets of spacetime fields on G induce the ordinary Poisson brackets of spatial fields in the instantaneous phase space G 0 of the Dirac-ADM formalism. The canonical history action is manifestly invariant both under spacetime diffeomorphisms Diff Y and temporal diffeomorphisms Diff T. Both of these diffeomorphisms are explicitly represented by symplectomorphisms on the history phase space G. The resulting classical history phase space formalism is offered as a starting point for projection operator quantization and consistent histories interpretation of the bosonic string model
Duality between the Deconfined Quantum-Critical Point and the Bosonic Topological Transition
Directory of Open Access Journals (Sweden)
Yan Qi Qin
2017-09-01
Full Text Available Recently, significant progress has been made in (2+1-dimensional conformal field theories without supersymmetry. In particular, it was realized that different Lagrangians may be related by hidden dualities; i.e., seemingly different field theories may actually be identical in the infrared limit. Among all the proposed dualities, one has attracted particular interest in the field of strongly correlated quantum-matter systems: the one relating the easy-plane noncompact CP^{1} model (NCCP^{1} and noncompact quantum electrodynamics (QED with two flavors (N=2 of massless two-component Dirac fermions. The easy-plane NCCP^{1} model is the field theory of the putative deconfined quantum-critical point separating a planar (XY antiferromagnet and a dimerized (valence-bond solid ground state, while N=2 noncompact QED is the theory for the transition between a bosonic symmetry-protected topological phase and a trivial Mott insulator. In this work, we present strong numerical support for the proposed duality. We realize the N=2 noncompact QED at a critical point of an interacting fermion model on the bilayer honeycomb lattice and study it using determinant quantum Monte Carlo (QMC simulations. Using stochastic series expansion QMC simulations, we study a planar version of the S=1/2 J-Q spin Hamiltonian (a quantum XY model with additional multispin couplings and show that it hosts a continuous transition between the XY magnet and the valence-bond solid. The duality between the two systems, following from a mapping of their phase diagrams extending from their respective critical points, is supported by the good agreement between the critical exponents according to the proposed duality relationships. In the J-Q model, we find both continuous and first-order transitions, depending on the degree of planar anisotropy, with deconfined quantum criticality surviving only up to moderate strengths of the anisotropy. This explains previous claims of no deconfined
Emerging bosons with three-body interactions from spin-1 atoms in optical lattices
International Nuclear Information System (INIS)
Mazza, L.; Rizzi, M.; Cirac, J. I.; Lewenstein, M.
2010-01-01
We study two many-body systems of bosons interacting via an infinite three-body contact repulsion in a lattice: a pairs quasicondensate induced by correlated hopping and the discrete version of the Pfaffian wave function. We propose to experimentally realize systems characterized by such interaction by means of a proper spin-1 lattice Hamiltonian: spin degrees of freedom are locally mapped into occupation numbers of emerging bosons, in a fashion similar to spin-1/2 and hardcore bosons. Such a system can be realized with ultracold spin-1 atoms in a Mott insulator with a filling factor of 1. The high versatility of these setups allows us to engineer spin-hopping operators breaking the SU(2) symmetry, as needed to approximate interesting bosonic Hamiltonians with three-body hardcore constraint. For this purpose we combine bichromatic spin-independent superlattices and Raman transitions to induce a different hopping rate for each spin orientation. Finally, we illustrate how our setup could be used to experimentally realize the first setup, that is, the transition to a pairs quasicondensed phase of the emerging bosons. We also report on a route toward the realization of a discrete bosonic Pfaffian wave function and list some open problems for reaching this goal.
Strongly first-order electroweak phase transition and classical scale invariance
Farzinnia, Arsham; Ren, Jing
2014-10-01
In this work, we examine the possibility of realizing a strongly first-order electroweak phase transition within the minimal classically scale-invariant extension of the standard model (SM), previously proposed and analyzed as a potential solution to the hierarchy problem. By introducing one complex gauge-singlet scalar and three (weak scale) right-handed Majorana neutrinos, the scenario was successfully rendered capable of achieving a radiative breaking of the electroweak symmetry (by means of the Coleman-Weinberg mechanism), inducing nonzero masses for the SM neutrinos (via the seesaw mechanism), presenting a pseudoscalar dark matter candidate (protected by the CP symmetry of the potential), and predicting the existence of a second CP-even boson (with suppressed couplings to the SM content) in addition to the 125 GeV scalar. In the present treatment, we construct the full finite-temperature one-loop effective potential of the model, including the resummed thermal daisy loops, and demonstrate that finite-temperature effects induce a first-order electroweak phase transition. Requiring the thermally driven first-order phase transition to be sufficiently strong at the onset of the bubble nucleation (corresponding to nucleation temperatures TN˜100-200 GeV) further constrains the model's parameter space; in particular, an O(0.01) fraction of the dark matter in the Universe may be simultaneously accommodated with a strongly first-order electroweak phase transition. Moreover, such a phase transition disfavors right-handed Majorana neutrino masses above several hundreds of GeV, confines the pseudoscalar dark matter masses to ˜1-2 TeV, predicts the mass of the second CP-even scalar to be ˜100-300 GeV, and requires the mixing angle between the CP-even components of the SM doublet and the complex singlet to lie within the range 0.2≲sinω ≲0.4. The obtained results are displayed in comprehensive exclusion plots, identifying the viable regions of the parameter space
International Nuclear Information System (INIS)
Mantry, Sonny; Petriello, Frank
2010-01-01
We derive a factorization theorem for the Higgs boson transverse momentum (p T ) and rapidity (Y) distributions at hadron colliders, using the soft-collinear effective theory (SCET), for m h >>p T >>Λ QCD , where m h denotes the Higgs mass. In addition to the factorization of the various scales involved, the perturbative physics at the p T scale is further factorized into two collinear impact-parameter beam functions (IBFs) and an inverse soft function (ISF). These newly defined functions are of a universal nature for the study of differential distributions at hadron colliders. The additional factorization of the p T -scale physics simplifies the implementation of higher order radiative corrections in α s (p T ). We derive formulas for factorization in both momentum and impact parameter space and discuss the relationship between them. Large logarithms of the relevant scales in the problem are summed using the renormalization group equations of the effective theories. Power corrections to the factorization theorem in p T /m h and Λ QCD /p T can be systematically derived. We perform multiple consistency checks on our factorization theorem including a comparison with known fixed-order QCD results. We compare the SCET factorization theorem with the Collins-Soper-Sterman approach to low-p T resummation.
Nonstatic one-boson-exchange potential with retardation
International Nuclear Information System (INIS)
Obinata, Toshio; Wada, Masanobu
1975-01-01
A one-boson-exchange potential (OBEP) with retardation represented in coordinate space is proposed, that produces a good fit to the experimental data such as the nuclear phase shifts, the deuteron properties and two-nucleon low-energy parameters. In addition to the scalar sigma 0 and Δ mesons, the well-established π, eta, ω and rho mesons have been exchanged in our OBEP. In the core region the hard core, Gaussian soft core and velocity-dependent core potentials are adopted. The characteristics of the retardation are discussed in detail as compared with those given in momentum space calculations. The OBEP's with and without retardation reproduce essentially the same phase shifts in spite of very different potential shapes, in particular in the central-to-tensor ratio. (auth.)
Energy Technology Data Exchange (ETDEWEB)
Vecchia, Paolo Di [The Niels Bohr Institute, University of Copenhagen,Blegdamsvej 17, DK-2100 Copenhagen Ø (Denmark); Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden); Marotta, Raffaele [Istituto Nazionale di Fisica Nucleare, Sezione di Napoli,Complesso Universitario di Monte S. Angelo ed. 6, via Cintia, 80126, Napoli (Italy); Mojaza, Matin [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, 14476 Potsdam (Germany)
2016-12-06
We consider the tree-level scattering amplitudes in the NS-NS (Neveu-Schwarz) massless sector of closed superstrings in the case where one external state becomes soft. We compute the amplitudes generically for any number of dimensions and any number and kind of the massless closed states through the subsubleading order in the soft expansion. We show that, when the soft state is a graviton or a dilaton, the full result can be expressed as a soft theorem factorizing the amplitude in a soft and a hard part. This behavior is similar to what has previously been observed in field theory and in the bosonic string. Differently from the bosonic string, the supersymmetric soft theorem for the graviton has no string corrections at subsubleading order. The dilaton soft theorem, on the other hand, is found to be universally free of string corrections in any string theory.
DEFF Research Database (Denmark)
di Vecchia, Paolo; Marotta, Raffaele; Mojaza, Matin
2016-01-01
We consider the tree-level scattering amplitudes in the NS-NS (Neveu-Schwarz) massless sector of closed superstrings in the case where one external state becomes soft. We compute the amplitudes generically for any number of dimensions and any number and kind of the massless closed states through...... the subsubleading order in the soft expansion. We show that, when the soft state is a graviton or a dilaton, the full result can be expressed as a soft theorem factorizing the amplitude in a soft and a hard part. This behavior is similar to what has previously been observed in field theory and in the bosonic string....... Differently from the bosonic string, the supersymmetric soft theorem for the graviton has no string corrections at subsubleading order. The dilaton soft theorem, on the other hand, is found to be universally free of string corrections in any string theory....
Many-body Anderson localization of strongly interacting bosons in random lattices
International Nuclear Information System (INIS)
Katzer, Roman
2015-05-01
In the present work, we investigate the problem of many-body localization of strongly interacting bosons in random lattices within the disordered Bose-Hubbard model. This involves treating both the local Mott-Hubbard physics as well as the non-local quantum interference processes, which give rise to the phenomenon of Anderson localization, within the same theory. In order to determine the interaction induced transition to the Mott insulator phase, it is necessary to treat the local particle interaction exactly. Therefore, here we use a mean-field approach that approximates only the kinetic term of the Hamiltonian. This way, the full problem of interacting bosons on a random lattice is reduced to a local problem of a single site coupled to a particle bath, which has to be solved self-consistently. In accordance to previous works, we find that a finite disorder width leads to a reduced size of the Mott insulating regions. The transition from the superfluid phase to the Bose glass phase is driven by the non-local effect of Anderson localization. In order to describe this transition, one needs to work within a theory that is non-local as well. Therefore, here we introduce a new approach to the problem. Based on the results for the local excitation spectrum obtained within the mean-field theory, we reduce the full, interacting model to an effective, non-interacting model by applying a truncation scheme to the Hilbert space. Evaluating the long-ranged current density within this approximation, we identify the transition from the Bose glass to the superfluid phase with the Anderson transition of the effective model. Resolving this transition using the self-consistent theory of localization, we obtain the full phase diagram of the disordered Bose-Hubbard model in the regime of strong interaction and larger disorder. In accordance to the theorem of inclusions, we find that the Mott insulator and the superfluid phase are always separated by the compressible, but insulating
Phase Transitions in Algebraic Cluster Models
International Nuclear Information System (INIS)
Yepez-Martinez, H.; Cseh, J.; Hess, P.O.
2006-01-01
same, and the states are said to form a (soft) band. The phase-transitions, as well as the persistence of the quasidynamical symmetries in the algebraic models of quadrupole collectivity have extensively been studied. In a recent work [1] we have addressed these questions in relation with another important collectivity of nuclei, i.e. clusterization. Two models were considered, a phenomenological one, containing no Pauli-principle, and a semimicroscopic one, which is based on a microscopically determined model space, being free from the Pauli-forbidden states. The interactions were treated in a phenomenologic and algebraic way in both cases. In this respect the two models have a similar group-structure. We have studied the SU(3) - SO(4) phase transition, related to the description of the relative motion in terms of the vibron model (in its simplest form in the phenomenological model and in a properly truncated form in the semimicroscopic description). The analytical study of the large-N limit of both models shows a first order phase transition. We have carried out numerical calculations as well. Three binary cluster systems were chosen, in which the number of open-shell clusters were zero, one and two, respectively. The numerical studies show that the phase transition is smoothed out for finite N systems, but some fingerprints of it still can be seen. The appearance of the quasidynamical SU(3) symmetry has also been studied, when moving away from the limit of the real SU(3) dynamical symmetry. It turned out that in each case, when there is a real dynamical symmetry in the limiting case (in the sense that a well-defined SU(3) quantum number can be associated to a band), this symmetry survives as quasidynamical symmetry at least up to the critical value of the control parameter. (author)
Huber, Patrick
2015-03-01
Spatial confinement in nanoporous media affects the structure, thermodynamics and mobility of molecular soft matter often markedly. This article reviews thermodynamic equilibrium phenomena, such as physisorption, capillary condensation, crystallisation, self-diffusion, and structural phase transitions as well as selected aspects of the emerging field of spatially confined, non-equilibrium physics, i.e. the rheology of liquids, capillarity-driven flow phenomena, and imbibition front broadening in nanoporous materials. The observations in the nanoscale systems are related to the corresponding bulk phenomenologies. The complexity of the confined molecular species is varied from simple building blocks, like noble gas atoms, normal alkanes and alcohols to liquid crystals, polymers, ionic liquids, proteins and water. Mostly, experiments with mesoporous solids of alumina, gold, carbon, silica, and silicon with pore diameters ranging from a few up to 50 nm are presented. The observed peculiarities of nanopore-confined condensed matter are also discussed with regard to applications. A particular emphasis is put on texture formation upon crystallisation in nanoporous media, a topic both of high fundamental interest and of increasing nanotechnological importance, e.g. for the synthesis of organic/inorganic hybrid materials by melt infiltration, the usage of nanoporous solids in crystal nucleation or in template-assisted electrochemical deposition of nano structures.
Khan, Hasan; Gazit, Snir; Randeria, Mohit; Trivedi, Nandini
The superconductor-insulator transition (SIT) in two dimensions is a paradigm for quantum criticality that has been observed experimentally in Josephson junction arrays, superconducting thin films, and cold atoms trapped in an optical lattice. The conventional picture of the transition is in terms of the condensation of bosonic degrees of freedom (Cooper pairs in superconductors). Interestingly, the transition has a dual description, where the insulating phase is a Bose condensate of vortices. We study the SIT numerically by means of a large-scale quantum Monte Carlo (QMC) simulation in the vortex representation. This provides direct access to both the boson and vortex degrees of freedom and allows us to numerically test the duality and quantify deviations from self-duality. Our main focus is on critical properties such as the vortex and the boson phase stiffness. We compare our results to previous studies in the bosonic representation. We acknowledge support from Grant DOE-BES DE-FG02-07ER46423 (HK, NT).
Beyond the hypothesis: Theory's role in the genesis, opposition, and pursuit of the Higgs boson
Wells, James D.
2018-05-01
The centrally recognized theoretical achievement that enabled the Higgs boson discovery in 2012 was the hypothesis of its existence, made by Peter Higgs in 1964. Nevertheless, there is a significant body of comparably important theoretical work prior to and after the Higgs boson hypothesis. In this article we present an additional perspective of how crucial theory work was to the genesis of the Higgs boson hypothesis, especially emphasizing its roots in Landau's theory of phase transitions and subsequent theoretical work on superconductivity. A detailed description is then given of the opposition to the Higgs boson hypothesis by many researchers, giving evidence to its speculative nature. And finally, it is discussed the importance of theory work in the decades after the hypothesis in order to make possible the experimental discovery of the Higgs boson.
μ+e-↔μ-e+ transitions via neutral scalar bosons
International Nuclear Information System (INIS)
Hou, W.; Wong, G.
1996-01-01
With μ→eγ decay forbidden by multiplicative lepton number conservation, we study muonium-antimuonium transitions induced by neutral scalar bosons. Pseudoscalars do not induce conversion for triplet muonium, while, for singlet muonium, pseudoscalar and scalar contributions add constructively. This is in contrast with the usual case of doubly charged scalar exchange, where the conversion rate is the same for both singlet and triplet muonium. Complementary to muonium conversion studies, high energy μ + e - →μ - e + and e - e - →μ - μ - collisions could reveal spectacular resonance peaks for the cases of neutral and doubly charged scalars, respectively. copyright 1996 The American Physical Society
Microscopy of bosonic models using Schwinger and Holstein - Primakoff bosonization techniques
International Nuclear Information System (INIS)
Pinto, M.E.B.
1988-01-01
Two kinds of bosonic expansions for the SU(2) case, one being finite (Schwinger) and the other being infinite (Holstein-Primakoff) are analysed. The existence of a transformation connecting them was discussed. Utilizing the two methods, the Two Level Model hamiltonian into the many boson space is mapped. Considering systems composed by 4, 6 and 14 particles, calculations for the eigenenergies within the ''vibrational limit'' of the model were performed. The results show that the Schwinger mapping is exact. Approximated bosonic images with the Holstein-Primakoff mapping are obtained. Indeed, the anharmonicities observed in the region between the ideal '' spherical limit'' and the ''transitional point'', were well described by the approximation containing up to quartic terms on the bosonic operators. (author) [pt
A test of boson mappings of fermion systems
International Nuclear Information System (INIS)
Arima, A.; Yoshida, N.; Ginocchio, J.N.
1981-01-01
The Otsuka-Arima-Iachello Method, the Belyaev-Zelevinsky-Marshalek boson expansion method, and the boson expansion theory are each used to map a solvable fermion hamiltonian onto a boson space. Comparison of the spectra and transition rates obtained by these three boson mapping methods are compared to the exact values. (orig.)
Effect of smectic A temperature width on the soft mode in ferroelectric liquid crystals
Choudhary, A.; Kaur, S.; Prakash, J.; Sreenivas, K.; Bawa, S. S.; Biradar, A. M.
2008-08-01
The behavior of soft mode range with respect to the temperature width of smectic A (Sm A) phase has been studied in four different ferroelectric liquid crystal (FLC) materials in the frequency range 10Hz-10MHz. The studies have been carried out in a planarly well aligned cells at different temperatures and different bias fields in Sm C* and Sm A phases. Dielectric studies of these FLCs near Sm C*-Sm A phase transition show that the temperature range of soft mode relaxation frequency phenomenon varies with the temperature width of Sm A phase. The dependence of tilt angle on temperature shows the nature of the order of transition at Sm C*-Sm A phase. The coupling between order parameters of Sm C* and Sm A phase influences the soft mode and phase transition in Sm C* and Sm A phases.
Macroscopic Quantum States and Quantum Phase Transition in the Dicke Model
International Nuclear Information System (INIS)
Lian Jin-Ling; Zhang Yuan-Wei; Liang Jiu-Qing
2012-01-01
The energy spectrum of Dicke Hamiltonians with and without the rotating wave approximation for an arbitrary atom number is obtained analytically by means of the variational method, in which the effective pseudo-spin Hamiltonian resulting from the expectation value in the boson-field coherent state is diagonalized by the spin-coherent-state transformation. In addition to the ground-state energy, an excited macroscopic quantum-state is found corresponding to the south- and north-pole gauges of the spin-coherent states, respectively. Our results of ground-state energies in exact agreement with various approaches show that these models exhibit a zero-temperature quantum phase transition of the second order for any number of atoms, which was commonly considered as a phenomenon of the thermodynamic limit with the atom number tending to infinity. The critical behavior of the geometric phase is analyzed. (general)
Energy Technology Data Exchange (ETDEWEB)
Zhang, Dong-Rui; Jiang, Wei-Zhou; Wei, Si-Na; Yang, Rong-Yao [Southeast University, Department of Physics, Nanjing (China); Xiang, Qian-Fei [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China)
2016-05-15
It has been a puzzle whether quarks may exist in the interior of massive neutron stars, since the hadron-quark phase transition softens the equation of state (EOS) and reduce the neutron star (NS) maximum mass very significantly. In this work, we consider the light U-boson that increases the NS maximum mass appreciably through its weak coupling to fermions. The inclusion of the U-boson may thus allow the existence of the quark degrees of freedom in the interior of large mass neutron stars. Unlike the consequence of the U-boson in hadronic matter, the stiffening role of the U-boson in the hybrid EOS is not sensitive to the choice of the hadron phase models. In addition, we have also investigated the effect of the effective QCD correction on the hybrid EOS. This correction may reduce the coupling strength of the U-boson that is needed to satisfy NS maximum mass constraint. While the inclusion of the U-boson also increases the NS radius significantly, we find that appropriate in-medium effects of the U-boson may reduce the NS radii significantly, satisfying both the NS radius and mass constraints well. (orig.)
Large enhancement of radiative strength for soft transitions in the quasicontinuum.
Voinov, A; Algin, E; Agvaanluvsan, U; Belgya, T; Chankova, R; Guttormsen, M; Mitchell, G E; Rekstad, J; Schiller, A; Siem, S
2004-10-01
Radiative strength functions (RSFs) for the (56,57)Fe nuclei below the separation energy are obtained from the 57Fe(3He,alphagamma)56Fe and 57Fe(3He,3He'gamma)57Fe reactions, respectively. An enhancement of more than a factor of 10 over common theoretical models of the soft (E(gamma) less than or approximately equal 2 MeV) RSF for transitions in the quasicontinuum (several MeV above the yrast line) is observed. Two-step cascade intensities with soft primary transitions from the 56Fe(n,2gamma)57Fe reaction confirm the enhancement.
Phase transitions in the Hubbard Hamiltonian
International Nuclear Information System (INIS)
Chaves, C.M.; Lederer, P.; Gomes, A.A.
1977-05-01
Phase transition in the isotropic non-degenerate Hubbard Hamiltonian within the renormalization group techniques is studied, using the epsilon = 4 - d expansion to first order in epsilon. The functional obtained from the Hubbard Hamiltonian displays full rotation symmetry and describes two coupled fields: a vector spin field, with n components and a non-soft scalar charge field. This coupling is pure imaginary, which has interesting consequences on the critical properties of this coupled field system. The effect of simple constraints imposed on the charge field is considered. The relevance of the coupling between the fields in producing Fisher renormalization of the critical exponents is discussed. The possible singularities introduced in the charge-charge correlation function by the coupling are also discussed
International Nuclear Information System (INIS)
Aoki, Y.; Csikor, F.; Fodor, Z.; Ukawa, A.
1999-01-01
We report results of a study of the end point of the electroweak phase transition of the SU(2) gauge-Higgs model defined on a four-dimensional isotropic lattice with N t = 2. Finite-size scaling study of Lee-Yang zeros yields λ c = 0.00116(16) for the end point. Combined with a zero-temperature measurement of Higgs and W boson masses, this leads to M H,c = 68.2 ± 6.6 GeV for the critical Higgs boson mass. An independent analysis of Binder cumulant gives a consistent value λ c = 0.00102(3) for the end point
International Nuclear Information System (INIS)
Petry, W.; Neuhaus, J.
1996-01-01
Many elements transform from a high temperature bcc phase to a more dense packed temperature phase. The great majority of these transitions are of 1st order, displacive and reconstructive. The lattice potentials which govern these martensitic transitions can be probed by inelastic neutron scattering, thereby answering fundamental questions like : Will the transition be announced by dynamical or static fluctuations? What are the trajectories for the displacements needed for the transformation? Does the vibrational entropy stabilize the high temperature phase? Are the unusual transport properties in these materials related to their ability to transform? (author) 17 figs., 1 tab., 46 refs
Energy Technology Data Exchange (ETDEWEB)
Petry, W; Neuhaus, J [Techn. Universitaet Muenchen, Physik Department E13, Munich (Germany)
1996-11-01
Many elements transform from a high temperature bcc phase to a more dense packed temperature phase. The great majority of these transitions are of 1st order, displacive and reconstructive. The lattice potentials which govern these martensitic transitions can be probed by inelastic neutron scattering, thereby answering fundamental questions like : Will the transition be announced by dynamical or static fluctuations? What are the trajectories for the displacements needed for the transformation? Does the vibrational entropy stabilize the high temperature phase? Are the unusual transport properties in these materials related to their ability to transform? (author) 17 figs., 1 tab., 46 refs.
Study of phase transition of even and odd nuclei based on q-deforme SU(1,1) algebraic model
Jafarizadeh, M. A.; Amiri, N.; Fouladi, N.; Ghapanvari, M.; Ranjbar, Z.
2018-04-01
The q-deformed Hamiltonian for the SO (6) ↔ U (5) transitional case in s, d interaction boson model (IBM) can be constructed by using affine SUq (1 , 1) Lie algebra in the both IBM-1 and 2 versions and IBFM. In this research paper, we have studied the energy spectra of 120-128Xe isotopes and 123-131Xe isotopes and B(E2) transition probabilities of 120-128Xe isotopes in the shape phase transition region between the spherical and gamma unstable deformed shapes of the theory of quantum deformation. The theoretical results agree with the experimental data fairly well. It is shown that the q-deformed SO (6) ↔ U (5) transitional dynamical symmetry remains after deformation.
Phase transitions in nuclear physics
Energy Technology Data Exchange (ETDEWEB)
Moretto, L.G.; Phair, L.; Wozniak, G.J.
1997-08-01
A critical overview of the low energy phase transitions in nuclei is presented with particular attention to the 2nd (1st) order pairing phase transitions, and to the 1st order liquid-vapor phase transition. The role of fluctuations in washing out these transitions is discussed and illustrated with examples. A robust indicator of phase coexistence in multifragmentation is presented.
Phase transitions in nuclear physics
International Nuclear Information System (INIS)
Moretto, L.G.; Phair, L.; Wozniak, G.J.
1997-08-01
A critical overview of the low energy phase transitions in nuclei is presented with particular attention to the 2nd (1st) order pairing phase transitions, and to the 1st order liquid-vapor phase transition. The role of fluctuations in washing out these transitions is discussed and illustrated with examples. A robust indicator of phase coexistence in multifragmentation is presented
Thermodynamics of phase transitions
International Nuclear Information System (INIS)
Cofta, H.
1972-01-01
The phenomenology of the phase transitions has been considered. The definitions of thermodynamic functions and parameters, as well as those of the phase transitions, are given and some of the relations between those quantities are discussed. The phase transitions classification proposed by Ehrenfest has been described. The most important features of phase transitions are discussed using the selected physical examples including the critical behaviour of ferromagnetic materials at the Curie temperature and antiferromagnetic materials at the Neel temperature. Some aspects of the Ehrenfest's equations, that have been derived, for the interfacial lines and surfaces are considered as well as the role the notion of interfaces. (S.B.)
String phase transitions in a strong magnetic field
Ferrara, Sergio; Ferrara, Sergio; Porrati, Massimo
1993-01-01
We consider open strings in an external constant magnetic field $H$. For an (infinite) sequence of critical values of $H$ an increasing number of (highest spin component) states lying on the first Regge trajectory becomes tachyonic. In the limit of infinite $H$ all these states are tachyons (with a common tachyonic mass) both in the case of the bosonic string and for the Neveu-Schwarz sector of the fermionic string. This result generalizes to extended object the same instability which occurs in ordinary non-Abelian gauge theories. The Ramond states have always positive square masses as is the case for ordinary QED. The weak field limit of the mass spectrum is the same as for a field theory with gyromagnetic ratio $g_S=2$ for all charged spin states. This behavior suggests a phase transition of the string as it has been argued for the ordinary electroweak theory.
Phase transitions modern applications
Gitterman, Moshe
2014-01-01
This book provides a comprehensive review of the theory of phase transitions and its modern applications, based on the five pillars of the modern theory of phase transitions i.e. the Ising model, mean field, scaling, renormalization group and universality. This expanded second edition includes, along with a description of vortices and high temperature superconductivity, a discussion of phase transitions in chemical reaction and moving systems. The book covers a close connection between phase transitions and small world phenomena as well as scale-free systems such as the stock market and the Internet. Readership: Scientists working in different fields of physics, chemistry, biology and economics as well as teaching material for undergraduate and graduate courses.
Goldstone boson condensation and effects of the axial anomaly in color superconductivity
Energy Technology Data Exchange (ETDEWEB)
Basler, Hannes Gregor Steffen
2011-01-12
One of the central objects of interest in high energy physics is the phase diagram of strongly interacting matter, the behavior of quarks and gluons in dependence of temperature and chemical potential. At very high densities and low temperatures it is expected that quarks form a superconductor, the so-called color superconductor. Such a color superconductor might be realized in the inner core of a neutron star. To study the phase structure of a color superconductor under neutron star conditions the Nambu-Jona-Lasinio model is used. The diquark condensates appearing in a color superconductor may break the original symmetries and give rise to Goldstone bosons. In this work we study the possible condensation of these Goldstone bosons. On the level of diquark condensates the condensation of Goldstone bosons is realized by a rotation of scalar into pseudoscalar diquark condensates. The phase diagram is studied, including pseudoscalar diquark condensates, for several different values of the lepton number chemical potential. The masses and thereby the condensation of the Goldstone bosons is effected by a six-point interaction that breaks the axial U(1) symmetry. Usually this six-point interaction is implemented in the NJL model in such a way that is does not effect the diquark sector. This can be fixed by adding an second six-point interaction term to the NJL Lagrangian. The coupling strength of this new interaction term has a great influence on the phase digram. In this context also the effect on the chiral phase transition is studied. (orig.)
Higgs bosons in supersymmetric models. Pt. 1
International Nuclear Information System (INIS)
Gunion, J.F.
1986-01-01
We describe the properties of Higgs bosons in a class of supersymmetric theories. We consider models in which the low-energy sector contains two weak complex doublets and perhaps one complex gauge-singlet Higgs field. Supersymmetry is assumed to be either softly or spontaneously broken, thereby imposing a number of restrictions on the Higgs boson parameters. We elucidate the Higgs boson masses and present Feynman rules for their couplings to the gauge bosons, fermions and scalars of the theory. We also present Feynman rules for vertices which are related by supersymmetry to the above couplings. Exact analytic expressions are given in two useful limits - one corresponding to the absence of the gauge-singlet Higgs field and the other corresponding to the absence of a supersymmetric Higgs mass term. (orig.)
Extended interacting boson model description of Pd nuclei in the A∼100 transitional region
Directory of Open Access Journals (Sweden)
Böyükata M.
2014-03-01
Full Text Available Studies of even-even nuclei in the A∼100 transitional mass region within the framework of the interacting boson model-1 (IBM-1 have been expanded down to 98Pd nuclei to compare the calculation with new experimental results from measurements obtained at the Institute of Nuclear Physics in Cologne. The low-lying energy levels and the E2 transition rates of 98−100Pd nuclei are investigated and their geometric structures are described in the present work. We have also focused on the new B(E2:21+ → 01+ values of 112,114Pd nuclei to compare with previously calculated values.
Phase transitions in surfactant monolayers
International Nuclear Information System (INIS)
Casson, B.D.
1998-01-01
Two-dimensional phase transitions have been studied in surfactant monolayers at the air/water interface by sum-frequency spectroscopy and ellipsometry. In equilibrium monolayers of medium-chain alcohols C n H 2n+1 OH (n = 9-14) a transition from a two-dimensional crystalline phase to a liquid was observed at temperatures above the bulk melting point. The small population of gauche defects in the solid phase increased only slightly at the phase transition. A model of the hydrocarbon chains as freely rotating rigid rods allowed the area per molecule and chain tilt in the liquid phase to be determined. The area per molecule, chain tilt and density of the liquid phase all increased with increasing chain length, but for each chain length the density was higher than in a bulk liquid hydrocarbon. In a monolayer of decanol adsorbed at the air/water interface a transition from a two-dimensional liquid to a gas was observed. A clear discontinuity in the coefficient of ellipticity as a function of temperature showed that the transition is first-order. This result suggests that liquid-gas phase transitions in surfactant monolayers may be more widespread than once thought. A solid-liquid phase transition has also been studied in mixed monolayers of dodecanol with an anionic surfactant (sodium dodecyl sulphate) and with a homologous series of cationic surfactants (alkyltrimethylammonium bromides: C n TABs, n = 12, 14, 16). The composition and structure of the mixed monolayers was studied above and below the phase transition. At low temperatures the mixed monolayers were as densely packed as a monolayer of pure dodecanol in its solid phase. At a fixed temperature the monolayers under-went a first-order phase transition to form a phase that was less dense and more conformationally disordered. The proportion of ionic surfactant in the mixed monolayer was greatest in the high temperature phase. As the chain length of the C n TAB increased the number of conformational defects
Criticality in the configuration-mixed interacting boson model: (1) U(5)-Q(χ)Q(χ) mixing
International Nuclear Information System (INIS)
Hellemans, V.; Van Isacker, P.; De Baerdemacker, S.; Heyde, K.
2007-01-01
The case of U(5)-Q(χ)Q(χ) mixing in the configuration-mixed interacting boson model is studied in its mean-field approximation. Phase diagrams with analytical and numerical solutions are constructed and discussed. Indications for first-order and second-order shape phase transitions can be obtained from binding energies and from critical exponents, respectively
Simulating and assessing boson sampling experiments with phase-space representations
Opanchuk, Bogdan; Rosales-Zárate, Laura; Reid, Margaret D.; Drummond, Peter D.
2018-04-01
The search for new, application-specific quantum computers designed to outperform any classical computer is driven by the ending of Moore's law and the quantum advantages potentially obtainable. Photonic networks are promising examples, with experimental demonstrations and potential for obtaining a quantum computer to solve problems believed classically impossible. This introduces a challenge: how does one design or understand such photonic networks? One must be able to calculate observables using general methods capable of treating arbitrary inputs, dissipation, and noise. We develop complex phase-space software for simulating these photonic networks, and apply this to boson sampling experiments. Our techniques give sampling errors orders of magnitude lower than experimental correlation measurements for the same number of samples. We show that these techniques remove systematic errors in previous algorithms for estimating correlations, with large improvements in errors in some cases. In addition, we obtain a scalable channel-combination strategy for assessment of boson sampling devices.
Phase transition in the non-degenerate Hubbard Hamiltonian
International Nuclear Information System (INIS)
Chaves, C.M.; Lederer, P.; Gomes, A.A.
1976-01-01
Phase transition in the isotropic non-degenerate Hubbard Hamiltonian within the renormalization group techniques, using the epsilon = 4 - d expansion to first order in epsilon, is studied. The functional obtained from the Hubbard Hamiltonian displays full rotation symmetry and describes two coupled fields: a vector spin field, with n components and a non-soft scalar charge field. The possibility of tricritical behavior then emerges. The effects of simple constraints imposed on the charge field is considered. The relevance of the coupling between the fields in producing Fisher renormalization of the critical exponents is discussed. The possible singularities introduced in the charge-charge correlation function by the coupling are also discussed
SnTe field effect transistors and the anomalous electrical response of structural phase transition
International Nuclear Information System (INIS)
Li, Haitao; Zhu, Hao; Yuan, Hui; Li, Qiliang; You, Lin; Kopanski, Joseph J.; Richter, Curt A.; Zhao, Erhai
2014-01-01
SnTe is a conventional thermoelectric material and has been newly found to be a topological crystalline insulator. In this work, back-gate SnTe field-effect transistors have been fabricated and fully characterized. The devices exhibit n-type transistor behaviors with excellent current-voltage characteristics and large on/off ratio (>10 6 ). The device threshold voltage, conductance, mobility, and subthreshold swing have been studied and compared at different temperatures. It is found that the subthreshold swings as a function of temperature have an apparent response to the SnTe phase transition between cubic and rhombohedral structures at 110 K. The abnormal and rapid increase in subthreshold swing around the phase transition temperature may be due to the soft phonon/structure change which causes the large increase in SnTe dielectric constant. Such an interesting and remarkable electrical response to phase transition at different temperatures makes the small SnTe transistor attractive for various electronic devices.
Li-ion batteries: Phase transition
International Nuclear Information System (INIS)
Hou Peiyu; Zhang Yantao; Zhang Lianqi; Chu Geng; Gao Jian
2016-01-01
Progress in the research on phase transitions during Li + extraction/insertion processes in typical battery materials is summarized as examples to illustrate the significance of understanding phase transition phenomena in Li-ion batteries. Physical phenomena such as phase transitions (and resultant phase diagrams) are often observed in Li-ion battery research and already play an important role in promoting Li-ion battery technology. For example, the phase transitions during Li + insertion/extraction are highly relevant to the thermodynamics and kinetics of Li-ion batteries, and even physical characteristics such as specific energy, power density, volume variation, and safety-related properties. (topical review)
SDG Fermion-Pair Algebraic SO(12) and Sp(10) Models and Their Boson Realizations
Navratil, P.; Geyer, H. B.; Dobes, J.; Dobaczewski, J.
1995-11-01
It is shown how the boson mapping formalism may be applied as a useful many-body tool to solve a fermion problem. This is done in the context of generalized Ginocchio models for which we introduce S-, D-, and G-pairs of fermions and subsequently construct the sdg-boson realizations of the generalized Dyson type. The constructed SO(12) and Sp(10) fermion models are solved beyond the explicit symmetry limits. Phase transitions to rotational structures are obtained also in situations where there is no underlying SU(3) symmetry.
An introduction to the interacting boson model
International Nuclear Information System (INIS)
Iachello, F.
1981-01-01
This chapter introduces an alternative, algebraic, description of the properties of nuclei with several particles outside the closed shells. Focuses on the group theory of the interacting boson model. Discusses the group structure of the boson Hamiltonian; subalgebras; the classification of states; dynamical symmetry; electromagnetic transition rates; transitional classes; and general cases. Omits a discussion of the latest developments (e.g., the introduction of proton and neutron degrees of freedom); the spectra of odd-A nuclei; and the bosonfermion model. Concludes that the major new feature of the interacting boson model is the introduction and systematic exploitation of algebraic techniques, which allows a simple and detailed description of many nuclear properties
New aspects of the interacting boson model
International Nuclear Information System (INIS)
Nadzakov, E.G.; Mikhajlov, I.N.
1987-01-01
In the framework of the boson space extension called interacting multiboson model: conserving the model basic dynamic symmetries, the s p d f boson model is considered. It does not destruct the intermediate mass nuclei simple description, and at the same time includes the number of levels and transitions, inaccessible to the usual s d boson model. Its applicability, even in a brief version, to the recently observed asymmetric nuclear shape effect in the Ra-Th-U region (and in other regions) with possible octupole and dipole deformation is demonstrated. It is done by reproducing algebraically the yrast lines of nuclei with vibrational, transitional and rotational spectra
X-slave boson approach to the periodic Anderson model
International Nuclear Information System (INIS)
Franco, R.; Figueira, M.S.; Foglio, M.E.
2001-01-01
The periodic anderson model (PAM) in the limit U=∞, can be studied by employing the Hubbard X operators to project out the unwanted states. In a previous work, we have studied the cumulant expansion of this Hamiltonian employing the hybridization as a perturbation, but probability conservation of the local states (completeness) is not usually satisfied when partial expansions like the 'chain approximation (CHA)' are employed. To consider this problem, we use a technique similar to the one employed by Coleman to treat the same problem with slave-bosons in the mean-field approximation. Assuming a particular renormalization for hybridization, we obtain a description that avoids an unwanted phase transition that appears in the mean-field slave-boson method at intermediate temperatures
Bosonization and entanglement spectrum for one-dimensional polar bosons on disordered lattices
International Nuclear Information System (INIS)
Deng, Xiaolong; Santos, Luis; Citro, Roberta; Orignac, Edmond; Minguzzi, Anna
2013-01-01
Ultra cold polar bosons in a disordered lattice potential, described by the extended Bose–Hubbard model, display a rich phase diagram. In the case of uniform random disorder one finds two insulating quantum phases—the Mott-insulator and the Haldane insulator—in addition to a superfluid and a Bose glass phase. In the case of a quasiperiodic potential, further phases are found, e.g. the incommensurate density wave, adiabatically connected to the Haldane insulator. For the case of weak random disorder we determine the phase boundaries using a perturbative bosonization approach. We then calculate the entanglement spectrum for both types of disorder, showing that it provides a good indication of the various phases. (paper)
Non-equilibrium phase transitions
Henkel, Malte; Lübeck, Sven
2009-01-01
This book describes two main classes of non-equilibrium phase-transitions: (a) static and dynamics of transitions into an absorbing state, and (b) dynamical scaling in far-from-equilibrium relaxation behaviour and ageing. The first volume begins with an introductory chapter which recalls the main concepts of phase-transitions, set for the convenience of the reader in an equilibrium context. The extension to non-equilibrium systems is made by using directed percolation as the main paradigm of absorbing phase transitions and in view of the richness of the known results an entire chapter is devoted to it, including a discussion of recent experimental results. Scaling theories and a large set of both numerical and analytical methods for the study of non-equilibrium phase transitions are thoroughly discussed. The techniques used for directed percolation are then extended to other universality classes and many important results on model parameters are provided for easy reference.
Phase transition in finite systems
International Nuclear Information System (INIS)
Chomaz, Ph.; Duflot, V.; Duflot, V.; Gulminelli, F.
2000-01-01
In this paper we present a review of selected aspects of Phase transitions in finite systems applied in particular to the liquid-gas phase transition in nuclei. We show that the problem of the non existence of boundary conditions can be solved by introducing a statistical ensemble with an averaged constrained volume. In such an ensemble the microcanonical heat capacity becomes negative in the transition region. We show that the caloric curve explicitly depends on the considered transformation of the volume with the excitation energy and so does not bear direct informations on the characteristics of the phase transition. Conversely, partial energy fluctuations are demonstrated to be a direct measure of the equation of state. Since the heat capacity has a negative branch in the phase transition region, the presence of abnormally large kinetic energy fluctuations is a signal of the liquid gas phase transition. (author)
Excitonic metal-insulator phase transition of the Mott type in compressed calcium
Voronkova, T. O.; Sarry, A. M.; Sarry, M. F.; Skidan, S. G.
2017-05-01
It has been experimentally found that, under the static compression of a calcium crystal at room temperature, it undergoes a series of structural phase transitions: face-centered cubic lattice → body-centered cubic lattice → simple cubic lattice. It has been decided to investigate precisely the simple cubic lattice (because it is an alternative lattice) with the aim of elucidating the possibility of the existence of other (nonstructural) phase transitions in it by using for this purpose the Hubbard model for electrons with half-filled ns-bands and preliminarily transforming the initial electronic system into an electron-hole system by means of the known Shiba operators (applicable only to alternative lattices). This transformation leads to the fact that, in the new system of fermions, instead of the former repulsion, there is an attraction between electrons and holes. Elementary excitations of this new system are bound boson pairs—excitons. This system of fermions has been quantitatively analyzed by jointly using the equation-of-motion method and the direct algebraic method. The numerical integration of the analytically exact transcendental equations derived from the first principles for alternative (one-, two-, and three-dimensional) lattices has demonstrated that, in systems of two-species (electrons + hole) fermions, temperature-induced metal-insulator phase transitions of the Mott type are actually possible. Moreover, all these crystals are in fact excitonic insulators. This conclusion is in complete agreement with the analytically exact calculations of the ground state of a one-dimensional crystal (with half-filled bands), which were performed by Lieb and Wu with the aim to find out the Mott insulator-metal transition of another type.
Directory of Open Access Journals (Sweden)
E. Fertman
2015-07-01
Full Text Available The temperature dependences of the elastic and magnetic properties of polycrystalline perovskite manganite La2/3Ba1/3MnO3 were studied using ultrasonic and SQUID magnetometer techniques. The minimum of the temperature-dependent sound velocity v(T and corresponding maximum of the decrement δ(T were found in the vicinity of the structural phase transition R 3 ̄ c ↔ I m m a at Ts ∼ 200 K. Large alterations of v and δ indicate a structural phase transition of the soft mode type. A high sensitivity of dc magnetization to a low uniaxial pressure caused by the softening was found in the Ts region. A negative value of the linear thermal expansion coefficient along one of the crystallographic axis was found in the Imma phase near Ts. The proposed microscopic mechanism explains the appearance of the soft mode in the vicinity of the structural phase transition temperature associated with the displacement of the manganese atom from the center of the oxygen octahedron.
Role of oxygen disorder in the ferroelectric phase transitions for various materials
International Nuclear Information System (INIS)
Pasciak, Marek; Goossens, Darren J.; Welberry, Richard T.
2009-01-01
Full text: The nature of ferroelectric phase transitions in many materials have been questioned for many years. Whereas some methods provide definitive evidence of mode softening, other methods, such as local structure probes, indicate the existence of disorder in the paraelectric phase [1]. It is now widely accepted, that the ferroelectric phase transition usually has two components - soft-mode displacive and order-disorder. The latter leads inevitably to some form of pretransitional clusters in the paraelectric phase [2]. In relaxor ferroelectrics, in which disorder drives the transformation, such polar clusters can exist over a wide range of temperatures. Diffuse scattering is a powerful tool for studying such disorder and also for studying short-range order correlations in atomic displacements [3]. In this work we concentrate on the role of oxygens in various materials. By different means of molecular simulations we build models in which the oxygens constitute a framework for short range order correlations. This leads to a discussion of the differences between x-ray and neutron diffuse scattering patterns that may arise due to the disorder of oxygens.
Effective theory of bosonic superfluids
International Nuclear Information System (INIS)
Schakel, A.M.J.
1994-01-01
The authors discuss the effective theory of a bosonic superfluid whose microscopic behavior is described by a nonrelativistic, weak-coupling φ 4 theory in the phase with broken particle number symmetry, both at zero temperature and in the vicinity of the phase transition. In the zero-temperature regime, the theory is governed by the gapless Goldstone mode resulting from the broken symmetry. Although this mode is gapless, the effective theory turns out to be Gallilei invariant. The regime just below the critical temperature is approached in a high-temperature expansion which is shown to be consistent with the weak-coupling assumption of the theory. The authors calculate the critical temperature, the coefficients of the Landau theory, and the finite-temperature sound velocity. A comparison with BCS theory is given
g-boson degree of freedom in vibrational regions
International Nuclear Information System (INIS)
Di Yaomin
1991-01-01
The g-boson degree of freedom in the vibrational regions is discussed in term of the energies and the electromagnetic transitions. Several closed expressions for the rates of M1, E2 transitions and the E2, M1 mixing ratios are obtained. Some survey is made and it reveals it is meaningful to investigate the g-boson degree of freedom in those regions
Probing Electroweak Phase Transition via Enhanced Di-Higgs Production
Energy Technology Data Exchange (ETDEWEB)
Carena, Marcela [Chicago U., KICP; Liu, Zhen [Fermilab; Riembau, Marc [DESY
2018-01-02
We consider a singlet extension of the Standard Model (SM) with a spontaneous $Z_2$ breaking and study the gluon-gluon fusion production of the heavy scalar, with subsequent decay into a pair of SM-like Higgs bosons. We find that an on-shell interference effect can notably enhance the resonant di-Higgs production rate up to 40\\%. In addition, consistently taking into account both the on-shell and off-shell interference effects between the heavy scalar and the SM di-Higgs diagrams significantly improves the HL-LHC and HE-LHC reach in this channel. As an example, within an effective field theory analysis in an explicitly $Z_2$ breaking scenario, we further discuss the potential to probe the parameter region compatible with a first order electroweak phase transition. Our analysis is applicable for general potentials of the singlet extension of the SM as well as for more general resonance searches.
Emergent Chiral Spin State in the Mott Phase of a Bosonic Kane-Mele-Hubbard Model
Plekhanov, Kirill; Vasić, Ivana; Petrescu, Alexandru; Nirwan, Rajbir; Roux, Guillaume; Hofstetter, Walter; Le Hur, Karyn
2018-04-01
Recently, the frustrated X Y model for spins 1 /2 on the honeycomb lattice has attracted a lot of attention in relation with the possibility to realize a chiral spin liquid state. This model is relevant to the physics of some quantum magnets. Using the flexibility of ultracold atom setups, we propose an alternative way to realize this model through the Mott regime of the bosonic Kane-Mele-Hubbard model. The phase diagram of this model is derived using bosonic dynamical mean-field theory. Focusing on the Mott phase, we investigate its magnetic properties as a function of frustration. We do find an emergent chiral spin state in the intermediate frustration regime. Using exact diagonalization we study more closely the physics of the effective frustrated X Y model and the properties of the chiral spin state. This gapped phase displays a chiral order, breaking time-reversal and parity symmetry, but is not topologically ordered (the Chern number is zero).
The nuclear liquid gas phase transition and phase coexistence
International Nuclear Information System (INIS)
Chomaz, Ph.
2001-01-01
In this talk we will review the different signals of liquid gas phase transition in nuclei. From the theoretical side we will first discuss the foundations of the concept of equilibrium, phase transition and critical behaviors in infinite and finite systems. From the experimental point of view we will first recall the evidences for some strong modification of the behavior of hot nuclei. Then we will review quantitative detailed analysis aiming to evidence phase transition, to define its order and phase diagram. Finally, we will present a critical discussion of the present status of phase transitions in nuclei and we will draw some lines for future development of this field. (author)
The nuclear liquid gas phase transition and phase coexistence
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph
2001-07-01
In this talk we will review the different signals of liquid gas phase transition in nuclei. From the theoretical side we will first discuss the foundations of the concept of equilibrium, phase transition and critical behaviors in infinite and finite systems. From the experimental point of view we will first recall the evidences for some strong modification of the behavior of hot nuclei. Then we will review quantitative detailed analysis aiming to evidence phase transition, to define its order and phase diagram. Finally, we will present a critical discussion of the present status of phase transitions in nuclei and we will draw some lines for future development of this field. (author)
Stable-unstable transition for a Bose-Hubbard chain coupled to an environment
Guo, Chu; de Vega, Ines; Schollwöck, Ulrich; Poletti, Dario
2018-05-01
Interactions in quantum systems may induce transitions to exotic correlated phases of matter which can be vulnerable to coupling to an environment. Here, we study the stability of a Bose-Hubbard chain coupled to a bosonic bath at zero and nonzero temperature. We show that only above a critical interaction the chain loses bosons and its properties are significantly affected. The transition is of a different nature than the superfluid-Mott-insulator transition and occurs at a different critical interaction. We explain such a stable-unstable transition by the opening of a global charge gap. The comparison of accurate matrix product state simulations to approximative approaches that miss this transition reveals its many-body origin.
Can EU conditionality remedy soft budget constraints in transition countries?
DEFF Research Database (Denmark)
Schröder, Philipp J.H.; Brücker, Herbert; Weise, Christian
2005-01-01
Soft budget constraints (SBCs) are a persistent feature of transition economies and have been blamed for a lack of fiscal consolidation and sluggish growth. EU eastward enlargement has been conditioned on tackling SBCs. This paper analyzes such outside conditionality theoretically and empirically...
The B-L phase transition. Implications for cosmology and neutrinos
International Nuclear Information System (INIS)
Schmitz, Kai
2012-07-01
We investigate the possibility that the hot thermal phase of the early universe is ignited in consequence of the B-L phase transition, which represents the cosmological realization of the spontaneous breaking of the Abelian gauge symmetry associated with B-L, the difference between baryon number B and lepton number L. Prior to the B-L phase transition, the universe experiences a stage of hybrid inflation. Towards the end of inflation, the false vacuum of unbroken B-L symmetry decays, which entails tachyonic preheating as well as the production of cosmic strings. Observational constraints on this scenario require the B-L phase transition to take place at the scale of grand unification. The dynamics of the B-L breaking Higgs field and the B-L gauge degrees of freedom, in combination with thermal processes, generate an abundance of heavy (s)neutrinos. These (s)neutrinos decay into radiation, thereby reheating the universe, generating the baryon asymmetry of the universe and setting the stage for the thermal production of gravitinos. The B-L phase transition along with the (s)neutrino-driven reheating process hence represents an intriguing and testable mechanism to generate the initial conditions of the hot early universe. We study the B-L phase transition in the full supersymmetric Abelian Higgs model, for which we derive and discuss the Lagrangian in arbitrary and unitary gauge. As for the subsequent reheating process, we formulate the complete set of Boltzmann equations, the solutions of which enable us to give a detailed and time-resolved description of the evolution of all particle abundances during reheating. Assuming the gravitino to be the lightest superparticle (LSP), the requirement of consistency between hybrid inflation, leptogenesis and gravitino dark matter implies relations between neutrino parameters and superparticle masses, in particular a lower bound on the gravitino mass of 10GeV. As an alternative to gravitino dark matter, we consider the case of
The B-L phase transition. Implications for cosmology and neutrinos
Energy Technology Data Exchange (ETDEWEB)
Schmitz, Kai
2012-07-15
We investigate the possibility that the hot thermal phase of the early universe is ignited in consequence of the B-L phase transition, which represents the cosmological realization of the spontaneous breaking of the Abelian gauge symmetry associated with B-L, the difference between baryon number B and lepton number L. Prior to the B-L phase transition, the universe experiences a stage of hybrid inflation. Towards the end of inflation, the false vacuum of unbroken B-L symmetry decays, which entails tachyonic preheating as well as the production of cosmic strings. Observational constraints on this scenario require the B-L phase transition to take place at the scale of grand unification. The dynamics of the B-L breaking Higgs field and the B-L gauge degrees of freedom, in combination with thermal processes, generate an abundance of heavy (s)neutrinos. These (s)neutrinos decay into radiation, thereby reheating the universe, generating the baryon asymmetry of the universe and setting the stage for the thermal production of gravitinos. The B-L phase transition along with the (s)neutrino-driven reheating process hence represents an intriguing and testable mechanism to generate the initial conditions of the hot early universe. We study the B-L phase transition in the full supersymmetric Abelian Higgs model, for which we derive and discuss the Lagrangian in arbitrary and unitary gauge. As for the subsequent reheating process, we formulate the complete set of Boltzmann equations, the solutions of which enable us to give a detailed and time-resolved description of the evolution of all particle abundances during reheating. Assuming the gravitino to be the lightest superparticle (LSP), the requirement of consistency between hybrid inflation, leptogenesis and gravitino dark matter implies relations between neutrino parameters and superparticle masses, in particular a lower bound on the gravitino mass of 10GeV. As an alternative to gravitino dark matter, we consider the case of
SDG fermion-pair algebraic SO(12) and Sp(10) models and their boson realizations
International Nuclear Information System (INIS)
Navatil, P.; Geyer, H.B.; Dobes, J.
1995-01-01
It is shown how the boson mapping formalism may be applied as a useful many-body tool to solve a fermion problem. This is done in the context of generalized Ginocchio models for which the authors introduce S-, D-, and G-pairs of fermions and subsequently construct the sdg-boson realizations of the generalized Dyson type. The constructed SO(12) and Sp(10) fermion models are solved beyond the explicit symmetry limits. Phase transitions to rotational structures are obtained also in situations where there is no underlying SU(3) symmetry. 34 refs., 5 figs., 2 tabs
Magnetic resonance of phase transitions
Owens, Frank J; Farach, Horacio A
1979-01-01
Magnetic Resonance of Phase Transitions shows how the effects of phase transitions are manifested in the magnetic resonance data. The book discusses the basic concepts of structural phase and magnetic resonance; various types of magnetic resonances and their underlying principles; and the radiofrequency methods of nuclear magnetic resonance. The text also describes quadrupole methods; the microwave technique of electron spin resonance; and the Mössbauer effect. Phase transitions in various systems such as fluids, liquid crystals, and crystals, including paramagnets and ferroelectrics, are also
Can EU Conditionality Remedy Soft Budget Constraints in Transition Countries?
DEFF Research Database (Denmark)
Brücker, Herbert; Schröder, Philipp; Weise, Christian
2003-01-01
Soft budget constraints (SBCs) are a persistent feature of transition economies and have been blamed for i.a. a lack of fiscal consolidation and sluggish growth. EU eastward enlargement has - among other things - been conditioned on tackling SBCs. This paper analyses such outside conditionality...
Drake, Jeffrey T.; Prasad, Nadipuram R.
1999-01-01
This paper surveys recent advances in communications that utilize soft computing approaches to phase synchronization. Soft computing, as opposed to hard computing, is a collection of complementary methodologies that act in producing the most desirable control, decision, or estimation strategies. Recently, the communications area has explored the use of the principal constituents of soft computing, namely, fuzzy logic, neural networks, and genetic algorithms, for modeling, control, and most recently for the estimation of phase in phase-coherent communications. If the receiver in a digital communications system is phase-coherent, as is often the case, phase synchronization is required. Synchronization thus requires estimation and/or control at the receiver of an unknown or random phase offset.
Rakhimov, Abdulla; Askerzade, Iman N
2014-09-01
We have shown that the critical temperature of a Bose-Einstein condensate to a normal phase transition of noninteracting bosons in cubic optical lattices has a linear dependence on the filling factor, especially at large densities. The condensed fraction exhibits a linear power law dependence on temperature in contrast to the case of ideal homogeneous Bose gases.
Hellemans, V; De Baerdemacker, S; Heyde, K
2008-01-01
The case of U(5)--$\\hat{Q}(\\chi)\\cdot\\hat{Q}(\\chi)$ mixing in the configuration-mixed Interacting Boson Model is studied in its mean-field approximation. Phase diagrams with analytical and numerical solutions are constructed and discussed. Indications for first-order and second-order shape phase transitions can be obtained from binding energies and from critical exponents, respectively.
Electronically soft phases in manganites.
Milward, G C; Calderón, M J; Littlewood, P B
2005-02-10
The phenomenon of colossal magnetoresistance in manganites is generally agreed to be a result of competition between crystal phases with different electronic, magnetic and structural order; a competition which can be strong enough to cause phase separation between metallic ferromagnetic and insulating charge-modulated states. Nevertheless, closer inspection of phase diagrams in many manganites reveals complex phases where the two order parameters of magnetism and charge modulation unexpectedly coexist. Here we show that such experiments can be naturally explained within a phenomenological Ginzburg-Landau theory. In contrast to models where phase separation originates from disorder or as a strain-induced kinetic phenomenon, we argue that magnetic and charge modulation coexist in new thermodynamic phases. This leads to a rich diagram of equilibrium phases, qualitatively similar to those seen experimentally. The success of this model argues for a fundamental reinterpretation of the nature of charge modulation in these materials, from a localized to a more extended 'charge-density wave' picture. The same symmetry considerations that favour textured coexistence of charge and magnetic order may apply to many electronic systems with competing phases. The resulting 'electronically soft' phases of matter with incommensurate, inhomogeneous and mixed order may be general phenomena in correlated systems.
Exact solutions of sl-boson system in U(2l + 1) reversible O(2l + 2) transitional region
Zhang Xin
2002-01-01
Exact eigen-energies and the corresponding wavefunctions of the interacting sl-boson system in U(2l + 1) reversible O(2l +2) transitional region are obtained by using an algebraic Bethe Ansatz with the infinite dimensional Lie algebraic technique. Numerical algorithm for solving the Bethe Ansatz equations by using mathematical package is also outlined
Soft QCD at the CMS and ATLAS experiments
Veres, Gabor
2016-01-01
A short overview of some of the recent results on soft QCD processes at the LHC will be presented from the ATLAS and CMS experiments. The discussion will proceed starting from the most inclusive to the more differential and rare phenomena. New results include total inelastic cross section measurements; studies of minimum bias collisions (charged particle $\\eta$ and $p_T$ distributions and two-particle correlations in high-multiplicity events); features of the underlying event (multiplicity and $\\Sigma p_T$ distributions in the presence of a high-$p_T$ track, jet, Z boson or $t\\overline{t}$ pair); minijets characterizing the transition between the soft and hard QCD regimes; dijets with a rapidity gap (as a signature of color-singlet exchange); M\\uller-Navelet dijets and their angular decorrelations (as an attempt to search for signs of the BFKL evolution and deviations from DGLAP); and finally, Double Parton Scattering (DPS) studies using various final states (4-jet events, $\\gamma$ + 3 jets, 2 b-jets and 2 je...
Kopaev, YuV
1992-01-01
Electronic Phase Transitions deals with topics, which are presently at the forefront of scientific research in modern solid-state theory. Anderson localization, which has fundamental implications in many areas of solid-state physics as well as spin glasses, with its influence on quite different research activities such as neural networks, are two examples that are reviewed in this book. The ab initio statistical mechanics of structural phase transitions is another prime example, where the interplay and connection of two unrelated disciplines of solid-state theory - first principle ele
Visible and dark matter from a first-order phase transition in a baryon-symmetric universe
International Nuclear Information System (INIS)
Petraki, Kalliopi; Volkas, Raymond R.; Trodden, Mark
2012-01-01
The similar cosmological abundances observed for visible and dark matter suggest a common origin for both. By viewing the dark matter density as a dark-sector asymmetry, mirroring the situation in the visible sector, we show that the visible and dark matter asymmetries may have arisen simultaneously through a first-order phase transition in the early universe. The dark asymmetry can then be equal and opposite to the usual visible matter asymmetry, leading to a universe that is symmetric with respect to a generalised baryon number. We present both a general structure, and a precisely defined example of a viable model of this type. In that example, the dark matter is ''atomic'' as well as asymmetric, and various cosmological and astrophysical constraints are derived. Testable consequences for colliders include a Z' boson that couples through the B−L charge to the visible sector, but also decays invisibly to dark sector particles. The additional scalar particles in the theory can mix with the standard Higgs boson and provide other striking signatures
Unconventional phase transitions in liquid crystals
Kats, E. I.
2017-12-01
According to classical textbooks on thermodynamics or statistical physics, there are only two types of phase transitions: continuous, or second-order, in which the latent heat L is zero, and first-order, in which L ≠ 0. Present-day textbooks and monographs also mention another, stand-alone type—the Berezinskii-Kosterlitz-Thouless transition, which exists only in two dimensions and shares some features with first- and second-order phase transitions. We discuss examples of non-conventional thermodynamic behavior (i.e., which is inconsistent with the theoretical phase transition paradigm now universally accepted). For phase transitions in smectic liquid crystals, mechanisms for nonconventional behavior are proposed and the predictions they imply are examined.
Universality in the phase behavior of soft matter: a law of corresponding states.
Malescio, G
2006-10-01
We show that the phase diagram of substances whose molecular structure changes upon varying the thermodynamic parameters can be mapped, through state-dependent scaling, onto the phase diagram of systems of molecules having fixed structure. This makes it possible to identify broad universality classes in the complex phase scenario exhibited by soft matter, and enlightens a surprisingly close connection between puzzling phase phenomena and familiar behaviors. The analysis presented provides a straightforward way for deriving the phase diagram of soft substances from that of simpler reference systems. This method is applied here to study the phase behavior exhibited by two significative examples of soft matter with temperature-dependent molecular structure: thermally responsive colloids and polymeric systems. A region of inverse melting, i.e., melting upon isobaric cooling, is predicted at relatively low pressure and temperature in polymeric systems.
Structural phase transitions and Huang scattering
International Nuclear Information System (INIS)
Yamada, Yasusada
1980-01-01
The usefulness of the application of the concept of Huang scattering to the understandings of the origin of diffuse scatterings near structural phase transitions are discussed. It is pointed out that in several phase transitions, the observed diffuse scatterings can not be interpreted in terms of critical fluctuations of the order parameters associated with the structural phase transitions, and that they are rather interpreted as Huang scattering due to random distribution of individual order parameter which is 'dressed' by strain fields. Examples to show effective applications of this concept to analyze the experimental X-ray data and whence to understand microscopic mechanisms of structural phase transitions are presented. (author)
Shape coexistence and phase transitions in the platinum isotopes
International Nuclear Information System (INIS)
Morales, Irving O.; Frank, Alejandro; Vargas, Carlos E.; Isacker, P. Van
2008-01-01
The matrix coherent-state approach of the interacting boson model with configuration mixing is used to study the geometry of the platinum isotopes. With a parameter set determined in previous studies, it is found that the absolute minimum of the potential for the Pt isotopes evolves from spherical to oblate and finally to prolate shapes when the neutron number decreases from N=126 (semi-magic) to N=104 (mid-shell). Shape coexistence is found in the isotopes 182,184,186,188 Pt. A phase diagram is constructed that shows the coexistence region as a function of the number of bosons and the strength of the mixing parameter
PAAR, [No Value; VORKAPIC, D; DIEPERINK, AEL
1991-01-01
We investigate the energy-level statistics in dependence on the boson number and the underlying classical motion for a system or collective states of zero angular momentum in gamma-soft nuclei described in the framework of the O(6) dynamical symmetry of the interacting boson model. This presents a
Modern theories of phase transitions
International Nuclear Information System (INIS)
Rajaraman, R.
1979-01-01
Modern applications of the ideas of phase transitions to nuclear systems and the modern techniques as applied to familiar phase transitions in solid-state physics are discussed with illustrations. The phenomenon of pion condensation in nuclei and neutron stars, is presented as an example of phase transitions in nuclear systems. The central physical ideas behind this subject as well as techniques used to tackle it are broadly summarised. It is pointed out that unlike familiar examples of ferromagnetism or superconductivity, the order parameter here has spatial variation even in the ground state. Possible experimental consequences are discussed. As an example of the second category, the use of renormalisation group techniques in solid state physics is reviewed. The basic idea behind the renormalisation group in the infra-red (thermodynamic) limit is presented. The observed universality and scaling of critical exponents in second order phase transitions is explained in a model-independent way. (auth.)
Abnormal number of Nambu-Goldstone bosons in the color-asymmetric 2SC phase of an NJL-type model
Blaschke, D.; Ebert, D.; Klimenko, K. G.; Volkov, M. K.; Yudichev, V. L.
2004-01-01
We consider an extended Nambu--Jona-Lasinio model including both (q \\bar q)- and (qq)-interactions with two light-quark flavors in the presence of a single (quark density) chemical potential. In the color superconducting phase of the quark matter the color SU(3) symmetry is spontaneously broken down to SU(2). If the usual counting of Goldstone bosons would apply, five Nambu-Goldstone (NG) bosons corresponding to the five broken color generators should appear in the mass spectrum. Unlike that ...
First-order character of the displacive structural transition in BaWO4
International Nuclear Information System (INIS)
Tan Da-Yong; Xiao Wan-Sheng; Zhou Wei; Chen Ming; Xiong Xiao-Lin; Song Mao-Shuang
2012-01-01
Nearly all displacive transitions have been considered to be continuous or second order, and the rigid unit mode (RUM) provides a natural candidate for the soft mode. However, in-situ X-ray diffraction and Raman measurements show clearly the first-order evidences for the scheelite-to-fergusonite displacive transition in BaWO 4 : a 1.6% volume collapse, coexistence of phases, and hysteresis on release of pressure. Such first-order signatures are found to be the same as the soft modes in BaWO 4 , which indicates the scheelite-to-fergusonite displacive phase transition hides a deeper physical mechanism. By the refinement of atomic displacement parameters, we further show that the first-order character of this phase transition stems from a coupling of large compression of soft BaO 8 polyhedrons to the small displacive distortion of rigid WO 4 tetrahedrons. Such a coupling will lead to a deeper physical insight in the phase transition of the common scheelite-structured compounds. (condensed matter: structural, mechanical, and thermal properties)
Energy Technology Data Exchange (ETDEWEB)
Qiu, Wujie [Department of Physics, East China Normal University, Shanghai 200241 (China); State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Lu, Ping; Yuan, Xun; Liu, Huili; Shi, Xun; Chen, Lidong [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); CAS Key Laboratory of Energy conversion Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Xu, Fangfang; Wu, Lihua [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Ke, Xuezhi, E-mail: wqzhang@mail.sic.ac.cn, E-mail: xzke@phy.ecnu.edu.cn, E-mail: jihuiy@uw.edu [Department of Physics, East China Normal University, Shanghai 200241 (China); Yang, Jiong [Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Yang, Jihui, E-mail: wqzhang@mail.sic.ac.cn, E-mail: xzke@phy.ecnu.edu.cn, E-mail: jihuiy@uw.edu [Materials Science and Engineering Department, University of Washington, Seattle, Washington 98195 (United States); Zhang, Wenqing, E-mail: wqzhang@mail.sic.ac.cn, E-mail: xzke@phy.ecnu.edu.cn, E-mail: jihuiy@uw.edu [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China)
2016-05-21
Quite a few interesting but controversial phenomena, such as simple chemical composition but complex structures, well-defined high-temperature cubic structure but intriguing phase transition, coexist in Cu{sub 2}Se, originating from the relatively rigid Se framework and “soft” Cu sublattice. However, the electrical transport properties are almost uninfluenced by such complex substructures, which make Cu{sub 2}Se a promising high-performance thermoelectric compound with extremely low thermal conductivity and good power factor. Our work reveals that the crystal structure of Cu{sub 2}Se at the temperature below the phase-transition point (∼400 K) should have a group of candidate structures that all contain a Se-dominated face-centered-cubic-like layered framework but nearly random site occupancy of atoms from the “soft” Cu sublattice. The energy differences among those structures are very low, implying the coexistence of various structures and thus an intrinsic structure complexity with a Se-based framework. Detailed analyses indicate that observed structures should be a random stacking of those representative structure units. The transition energy barriers between each two of those structures are estimated to be zero, leading to a polymorphous phase transition of Cu{sub 2}Se at increasing temperature. Those are all consistent with experimental observations.
Dynamics of a quantum phase transition
International Nuclear Information System (INIS)
Zurek, W.H.
2005-01-01
We present two approaches to the non-equilibrium dynamics of a quench-induced phase transition in quantum Ising model. First approach retraces steps of the standard calculation to thermodynamic second order phase transitions in the quantum setting. The second calculation is purely quantum, based on the Landau-Zener formula for transition probabilities in processes that involve avoided level crossings. We show that the two approaches yield compatible results for the scaling of the defect density with the quench rate. We exhibit similarities between them, and comment on the insights they give into dynamics of quantum phase transitions. (author)
Quantum phase transitions of strongly correlated electron systems
International Nuclear Information System (INIS)
Imada, Masatoshi
1998-01-01
Interacting electrons in solids undergo various quantum phase transitions driven by quantum fluctuations. The quantum transitions take place at zero temperature by changing a parameter to control quantum fluctuations rather than thermal fluctuations. In contrast to classical phase transitions driven by thermal fluctuations, the quantum transitions have many different features where quantum dynamics introduces a source of intrinsic fluctuations tightly connected with spatial correlations and they have been a subject of recent intensive studies as we see below. Interacting electron systems cannot be fully understood without deep analyses of the quantum phase transitions themselves, because they are widely seen and play essential roles in many phenomena. Typical and important examples of the quantum phase transitions include metal-insulator transitions, (2, 3, 4, 5, 6, 7, 8, 9) metal-superconductor transitions, superconductor-insulator transitions, magnetic transitions to antiferromagnetic or ferromagnetic phases in metals as well as in Mott insulators, and charge ordering transitions. Here, we focus on three different types of transitions
A modified two-level three-phase quasi-soft-switching inverter
DEFF Research Database (Denmark)
Liu, Yusheng; Wu, Weimin; Blaabjerg, Frede
2014-01-01
A traditional Voltage Source Inverter (VSI) has higher efficiency than a Current Voltage Source (CSI) due to the less conduction power loss. However, the reverse recovery of the free-wheeling diode limits the efficiency improvement for the silicon devices based hard-switching VSI. The traditional...... quasi-soft-switching inverter can alternate between VSI and CSI by using a proper control scheme and thereby reduce the power losses caused by the reverse recovery of the free-wheeling diode. Nevertheless, slightly extra conduction power loss of the auxiliary switch is also introduced. In order...... to reduce the extra conduction power loss and the voltage stress across the DC-link capacitor, a modified two-level three-phase quasi-soft-switching inverter is proposed by using a SiC MOSFET instead of an IGBT. The principle of the modified two-level three-phase quasi-soft-switching inverter is analyzed...
Discontinuous jamming transitions in soft materials: coexistence of flowing and jammed states
International Nuclear Information System (INIS)
Dennin, Michael
2008-01-01
Many systems in nature exhibit transitions between fluid-like states and solid-like states, or 'jamming transitions'. There is a strong theoretical foundation for understanding equilibrium phase transitions that involve solidification, or jamming. Other jamming transitions, such as the glass transition, are less well understood. The jamming phase diagram has been proposed to unify the description of equilibrium phase transitions, the glass transitions, and other nonequilibrium jamming transitions. As with equilibrium phase transitions, which can either be first order (discontinuous in a relevant order parameter) or second order (continuous), one would expect that generalized jamming transitions can be continuous or discontinuous. In studies of flow in complex fluids, there is a wide range of evidence for discontinuous transitions, mostly in the context of shear localization, or shear banding. In this paper, I review the experimental evidence for discontinuous transitions. I focus on systems in which there is a discontinuity in the rate of strain between two, coexisting states: one in which the material is flowing and the other in which it is solid-like. (topical review)
Superconductor-insulator transitions in 2D: the experimental situation
International Nuclear Information System (INIS)
Markovic, N.; Christiansen, C.; Mack, A.; Goldman, A.M.
2000-01-01
Superconductor-insulator (SI) transitions in ultrathin films have attracted significant attention over the last decade because of the possibility that they are quantum phase transitions. Magnetic field, film thickness, or carrier concentration can be used as control parameters. The bosonic pictures of these transitions proposed some years ago are only in qualitative agreement with experiment. In particular, the critical resistance appears not to be universal, and there are variations in the values of critical exponents. It has been concluded that in real films fermionic degrees of freedom must be taken into account. There are also indications that the phase diagram may include a significant metallic phase separating the superconducting and insulating phases, and that the transition may have a significant percolative aspect. The experimental situation will be broadly reviewed with attention paid to issues relating to materials and measurements. (orig.)
Phase transitions in finite systems
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph. [Grand Accelerateur National d' Ions Lourds (GANIL), DSM-CEA / IN2P3-CNRS, 14 - Caen (France); Gulminelli, F. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire
2002-07-01
In this series of lectures we will first review the general theory of phase transition in the framework of information theory and briefly address some of the well known mean field solutions of three dimensional problems. The theory of phase transitions in finite systems will then be discussed, with a special emphasis to the conceptual problems linked to a thermodynamical description for small, short-lived, open systems as metal clusters and data samples coming from nuclear collisions. The concept of negative heat capacity developed in the early seventies in the context of self-gravitating systems will be reinterpreted in the general framework of convexity anomalies of thermo-statistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. Finally a careful study of the thermodynamical limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. (authors)
Phase transitions in finite systems
International Nuclear Information System (INIS)
Chomaz, Ph.; Gulminelli, F.
2002-01-01
In this series of lectures we will first review the general theory of phase transition in the framework of information theory and briefly address some of the well known mean field solutions of three dimensional problems. The theory of phase transitions in finite systems will then be discussed, with a special emphasis to the conceptual problems linked to a thermodynamical description for small, short-lived, open systems as metal clusters and data samples coming from nuclear collisions. The concept of negative heat capacity developed in the early seventies in the context of self-gravitating systems will be reinterpreted in the general framework of convexity anomalies of thermo-statistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. Finally a careful study of the thermodynamical limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. (authors)
Microscopic foundation of the interacting boson model
International Nuclear Information System (INIS)
Arima, Akito
1994-01-01
A microscopic foundation of the interacting boson model is described. The importance of monopole and quadrupole pairs of nucleons is emphasized. Those pairs are mapped onto the s and d bosons. It is shown that this mapping provides a good approximation in vibrational and transitional nuclei. In appendix, it is shown that the monopole pair of electrons plays possibly an important role in metal clusters. (orig.)
Nano-scale patterns of polymers and their structural phase transitions
Energy Technology Data Exchange (ETDEWEB)
Matsushita, Yushu [Tokyo Univ. (Japan). Inst. for Solid State Physics
1998-03-01
Nano-scale patterns formed by polymers and their related soft materials were investigated by measuring neutron scattering from them. Two apparatuses installed at cold neutron guides in JRR-3M, a small angle neutron scattering (SANS) apparatus and a neutron reflectometer, which give out elastic scattering intensities, were used. Chain dimensions of polystyrenes diluted with low molecular weight homologous polystyrenes, orientation behaviour of microphase-separated block copolymer in concentrated solutions under shear, shrinkage and recovery of polyvinylalcohol gel with temperature and structural phase transition of microemulsion under high-pressure and so on were measured by SANS, while microphase-separated polystyrene(S)/poly(2-vinylpyridine)(P) interfaces of a PSP triblock copolymer was observed by specular neutron reflectivity measurements. (author)
Non-equilibrium phase transition
International Nuclear Information System (INIS)
Mottola, E.; Cooper, F.M.; Bishop, A.R.; Habib, S.; Kluger, Y.; Jensen, N.G.
1998-01-01
This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Non-equilibrium phase transitions play a central role in a very broad range of scientific areas, ranging from nuclear, particle, and astrophysics to condensed matter physics and the material and biological sciences. The aim of this project was to explore the path to a deeper and more fundamental understanding of the common physical principles underlying the complex real time dynamics of phase transitions. The main emphasis was on the development of general theoretical tools to deal with non-equilibrium processes, and of numerical methods robust enough to capture the time-evolving structures that occur in actual experimental situations. Specific applications to Laboratory multidivisional efforts in relativistic heavy-ion physics (transition to a new phase of nuclear matter consisting of a quark-gluon plasma) and layered high-temperature superconductors (critical currents and flux flow at the National High Magnetic Field Laboratory) were undertaken
Ma, Fengxian; Gao, Guoping; Jiao, Yalong; Gu, Yuantong; Bilic, Ante; Zhang, Haijun; Chen, Zhongfang; Du, Aijun
2016-02-01
Single layered transition metal dichalcogenides have attracted tremendous research interest due to their structural phase diversities. By using a global optimization approach, we have discovered a new phase of transition metal dichalcogenides (labelled as T''), which is confirmed to be energetically, dynamically and kinetically stable by our first-principles calculations. The new T'' MoS2 phase exhibits an intrinsic quantum spin Hall (QSH) effect with a nontrivial gap as large as 0.42 eV, suggesting that a two-dimensional (2D) topological insulator can be achieved at room temperature. Most interestingly, there is a topological phase transition simply driven by a small tensile strain of up to 2%. Furthermore, all the known MX2 (M = Mo or W; X = S, Se or Te) monolayers in the new T'' phase unambiguously display similar band topologies and strain controlled topological phase transitions. Our findings greatly enrich the 2D families of transition metal dichalcogenides and offer a feasible way to control the electronic states of 2D topological insulators for the fabrication of high-speed spintronics devices.Single layered transition metal dichalcogenides have attracted tremendous research interest due to their structural phase diversities. By using a global optimization approach, we have discovered a new phase of transition metal dichalcogenides (labelled as T''), which is confirmed to be energetically, dynamically and kinetically stable by our first-principles calculations. The new T'' MoS2 phase exhibits an intrinsic quantum spin Hall (QSH) effect with a nontrivial gap as large as 0.42 eV, suggesting that a two-dimensional (2D) topological insulator can be achieved at room temperature. Most interestingly, there is a topological phase transition simply driven by a small tensile strain of up to 2%. Furthermore, all the known MX2 (M = Mo or W; X = S, Se or Te) monolayers in the new T'' phase unambiguously display similar band topologies and strain controlled topological
Quark–hadron phase transition in massive gravity
Energy Technology Data Exchange (ETDEWEB)
Atazadeh, K., E-mail: atazadeh@azaruniv.ac.ir
2016-11-15
We study the quark–hadron phase transition in the framework of massive gravity. We show that the modification of the FRW cosmological equations leads to the quark–hadron phase transition in the early massive Universe. Using numerical analysis, we consider that a phase transition based on the chiral symmetry breaking after the electroweak transition, occurred at approximately 10 μs after the Big Bang to convert a plasma of free quarks and gluons into hadrons.
First order electroweak phase transition
International Nuclear Information System (INIS)
Buchmueller, W.; Fodor, Z.
1993-01-01
In this work, the authors have studied the phase transition in the SU(2)gauge theory at finite temperature. The authors' improved perturbative approach does not suffer from the infrared problems appearing in the ordinary loop expansion. The authors have calculated the effective potential up to cubic terms in the couplings. The higher order terms suggest that the method is reliable for Higgs masses smaller than 80 GeV. The authors have obtained a non-vanishing magnetic mass which further weakens the transitions. By use of Langer's theory of metastability, the authors have calculated the nucleation rate for critical bubbles and have discussed some cosmological consequences. For m H <80 GeV the phase transition is first order and proceeds via bubble nucleation and growth. The thin wall approximation is only marginally applicable. Since the phase transition is quite weak SM baryogenesis is unlikely. 8 refs., 5 figs
Sim, Taeyong; Choi, Ahnryul; Lee, Soeun; Mun, Joung Hwan
2017-10-01
The transition phase of a golf swing is considered to be a decisive instant required for a powerful swing. However, at the same time, the low back torsional loads during this phase can have a considerable effect on golf-related low back pain (LBP). Previous efforts to quantify the transition phase were hampered by problems with accuracy due to methodological limitations. In this study, vector-coding technique (VCT) method was proposed as a comprehensive methodology to quantify the precise transition phase and examine low back torsional load. Towards this end, transition phases were assessed using three different methods (VCT, lead hand speed and X-factor stretch) and compared; then, low back torsional load during the transition phase was examined. As a result, the importance of accurate transition phase quantification has been documented. The largest torsional loads were observed in healthy professional golfers (10.23 ± 1.69 N · kg -1 ), followed by professional golfers with a history of LBP (7.93 ± 1.79 N · kg -1 ), healthy amateur golfers (1.79 ± 1.05 N · kg -1 ) and amateur golfers with a history of LBP (0.99 ± 0.87 N · kg -1 ), which order was equal to that of the transition phase magnitudes of each group. These results indicate the relationship between the transition phase and LBP history and the dependency of the torsional load magnitude on the transition phase.
Gamma-unstable nuclei in the sdg boson model
Kuyucak, S.; Lac, V.-S.; Morrison, I.; Barret, B. R.
Following the recent Pt(p,p') experiments which indicated the need for high angular momentum (g) bosons to reproduce the E4 data, we have extended the O(6) limit of the sd boson model to the sdg bosons. It is shown that a gamma-unstable Hamiltonian in the sdg model consisting of a quadrupole interaction and a g boson energy leads to results that are very similar to the O(6) limit. Deviations from the empirical energy spectrum that stem from the gamma-unstable nature of the Hamiltonian can be improved by including a consistent hexadecapole interaction which induces triaxiality. The same hexadecapole operator can also account for the strong E4 transitions to the 4(sup +) states presumed to be g boson states. Specific applications are made to the Xe and Pt isotopes.
Measure synchronization in a spin-orbit-coupled bosonic Josephson junction
Wang, Wen-Yuan; Liu, Jie; Fu, Li-Bin
2015-11-01
We present measure synchronization (MS) in a bosonic Josephson junction with spin-orbit coupling. The two atomic hyperfine states are coupled by a Raman dressing scheme, and they are regarded as two orientations of a pseudo-spin-1 /2 system. A feature specific to a spin-orbit-coupled (SOC) bosonic Josephson junction is that the transition from non-MS to MS dynamics can be modulated by Raman laser intensity, even in the absence of interspin atomic interaction. A phase diagram of non-MS and MS dynamics as functions of Raman laser intensity and Josephson tunneling amplitude is presented. Taking into account interspin atomic interactions, the system exhibits MS breaking dynamics resulting from the competition between intraspin and interspin atomic interactions. When interspin atomic interactions dominate in the competition, the system always exhibits MS dynamics. For interspin interaction weaker than intraspin interaction, a window for non-MS dynamics is present. Since SOC Bose-Einstein condensates provide a powerful platform for studies on physical problems in various fields, the study of MS dynamics is valuable in researching the collective coherent dynamical behavior in a spin-orbit-coupled bosonic Josephson junction.
International Nuclear Information System (INIS)
Smolenskij, G.A.; Kolpakova, N.N.; Sher, E.S.; Brzhezina, B.
1986-01-01
Moderation of soft mode attenuation in the incommensurate phase in Cd 2 Nb 2 O 7 , K 2 SeO 4 and Rb 2 ZnBr 4 is observed at temperature drop and anomalous jump-like decrease of integral intensity of the soft mode under transition to the low-temperature commensurate phase. Anomalous behaviour of the soft mode is explained by wave amplitudon contribution (q=0) in Raman spectrum of the first order and composite tone (wave amplitudon (q=0) +- wave phase (q=K i )) in Raman spectrum of the second order. Relative contribution of the phase wave (q=K i ) to soft mode attenuation can be estimated supposing that wave amplitudon attenuation is G A ∼ (T i -T) -1 . ΔG f max makes up approximately 6 cm -1 in Cd 2 Nb 2 O 7 and approximately 3 cm -1 in K 2 SeO 4 and Rb 2 ZnBr 4 at temperatures above T c . In the low-temperature phase the soft mode corresponds to the wave amplitudon (q=0) in the Raman spectrum of the first order at T c - 26 K) in Cd 2 Nb 2 O 7 , T c - 13 K) in K 2 SeO 4 and T c - 163 K) in Rb 2 ZnBr 4
Rey, Marcel; Fernández-Rodríguez, Miguel Ángel; Steinacher, Mathias; Scheidegger, Laura; Geisel, Karen; Richtering, Walter; Squires, Todd M; Isa, Lucio
2016-04-21
We have studied the complete two-dimensional phase diagram of a core-shell microgel-laden fluid interface by synchronizing its compression with the deposition of the interfacial monolayer. Applying a new protocol, different positions on the substrate correspond to different values of the monolayer surface pressure and specific area. Analyzing the microstructure of the deposited monolayers, we discovered an isostructural solid-solid phase transition between two crystalline phases with the same hexagonal symmetry, but with two different lattice constants. The two phases corresponded to shell-shell and core-core inter-particle contacts, respectively; with increasing surface pressure the former mechanically failed enabling the particle cores to come into contact. In the phase-transition region, clusters of particles in core-core contacts nucleate, melting the surrounding shell-shell crystal, until the whole monolayer moves into the second phase. We furthermore measured the interfacial rheology of the monolayers as a function of the surface pressure using an interfacial microdisk rheometer. The interfaces always showed a strong elastic response, with a dip in the shear elastic modulus in correspondence with the melting of the shell-shell phase, followed by a steep increase upon the formation of a percolating network of the core-core contacts. These results demonstrate that the core-shell nature of the particles leads to a rich mechanical and structural behavior that can be externally tuned by compressing the interface, indicating new routes for applications, e.g. in surface patterning or emulsion stabilization.
Moreira, Roberto L.; Lobo, Ricardo P. S. M.; Ramos, Sérgio L. L. M.; Sebastian, Mailadil T.; Matinaga, Franklin M.; Righi, Ariete; Dias, Anderson
2018-05-01
The low-temperature vibrational properties of B a2ZnTe O6 double-perovskite ceramics obtained by the solid-state route were investigated by Raman scattering and Fourier-transform infrared reflectivity. We found that this material undergoes a reversible ferroelastic phase transition at around 140 K, well compatible with a recently proposed rhombohedral-to-monoclinic structural change that would occur below 165 K. Complementary calorimetric measurements showed that the phase transition has a first-order character, with an entropy jump compatible with a displacive mechanism. The vibrational spectra show clearly the splitting of the doubly degenerate E modes into nondegenerate representations of the low-symmetry phase. In particular, the lowest-frequency Raman mode presents soft-mode behavior and splits below the critical temperature, confirming the in-plane ferroelastic deformation in the low-temperature phase.
Deconfinement and Phase Diagram of Bosons in a Linear Optical Lattice with a Particle Reservoir
International Nuclear Information System (INIS)
Majumdar, Kingshuk; Fertig, H.A.
2005-01-01
We investigate the zero-temperature phases of bosons in a one-dimensional optical lattice with an explicit tunnel coupling to a Bose-condensed particle reservoir. Renormalization group analysis of this system is shown to reveal three phases: one in which the linear system is fully phase locked to the reservoir; one in which Josephson vortices between the one-dimensional system and the particle reservoir deconfine due to quantum fluctuations, leading to a decoupled state in which the one-dimensional system is metallic; and one in which the one-dimensional system is in a Mott insulating state
Effect of hyperons on nuclear phase transition
International Nuclear Information System (INIS)
Das, P.; Mallik, S.; Chaudhuri, G.
2016-01-01
Phase transition of nuclear system in heavy ion-collisions at intermediate energy has been studied well for many years and it has also been extended to strange nuclear matter. Recently, using the Canonical Thermodynamical Model (CTM), detailed work on multiplicity distribution of fragments produced from fragmentation of hypernuclear system shows the existence of phase transition or phase coexistence in strange system with Λ-hyperons. In present work we want to continue the investigation on phase transition with respect to some other thermodynamic observables like free energy, specific heat etc. in order to be confirmed about the nature of the transition
Generalized definitions of phase transitions
International Nuclear Information System (INIS)
Chomaz, Ph.; Gulminelli, F.
2001-09-01
We define a first order phase transition as a bimodality of the event distribution in the space of observations and we show that this is equivalent to a curvature anomaly of the thermodynamical potential and that it implies the Yang Lee behavior of the zeros of the partition sum. Moreover, it allows to study phase transitions out of equilibrium. (authors)
Quantum phase transition with dissipative frustration
Maile, D.; Andergassen, S.; Belzig, W.; Rastelli, G.
2018-04-01
We study the quantum phase transition of the one-dimensional phase model in the presence of dissipative frustration, provided by an interaction of the system with the environment through two noncommuting operators. Such a model can be realized in Josephson junction chains with shunt resistances and resistances between the chain and the ground. Using a self-consistent harmonic approximation, we determine the phase diagram at zero temperature which exhibits a quantum phase transition between an ordered phase, corresponding to the superconducting state, and a disordered phase, corresponding to the insulating state with localized superconducting charge. Interestingly, we find that the critical line separating the two phases has a nonmonotonic behavior as a function of the dissipative coupling strength. This result is a consequence of the frustration between (i) one dissipative coupling that quenches the quantum phase fluctuations favoring the ordered phase and (ii) one that quenches the quantum momentum (charge) fluctuations leading to a vanishing phase coherence. Moreover, within the self-consistent harmonic approximation, we analyze the dissipation induced crossover between a first and second order phase transition, showing that quantum frustration increases the range in which the phase transition is second order. The nonmonotonic behavior is reflected also in the purity of the system that quantifies the degree of correlation between the system and the environment, and in the logarithmic negativity as an entanglement measure that encodes the internal quantum correlations in the chain.
Long, G. L.; Ji, H. Y.
1998-04-01
B(E2, L+2-->L) transitions in the sdg interacting boson model SU(3) limit are studied with a general E2 transition operator. Analytical expressions are obtained using a group theoretic method. It is found that when using transition operators of the form (d†g~+g†d~)2 or (g†g~)2, the B(E2, L+2-->L) values in the ground-state band have an L(L+3) dependent term. As L increases, the B(E2) values can be larger than the rigid rotor model value. Application to 236,238U is discussed.
Gauge boson/Higgs boson unification: The Higgs bosons as superpartners of massive gauge bosons
International Nuclear Information System (INIS)
Fayet, P.
1984-01-01
We show how one can use massive gauge superfields to describe, simultaneously, gauge bosons (Wsup(+-), Z, ...) and Higgs bosons (wsup(+-), z, ...) together with their spin-1/2 partners (pairs of winos, zinos, ...), despite their different electroweak properties. This provides a manifestly supersymmetric formulation of spontaneously broken supersymmetric gauge theories, and makes explicit the relations between massive gauge bosons and Higgs bosons. It raises, however, the following question: if the gauge bosons Wsup(+-) and Z and the Higgs bosons wsup(+-) and z are related by supersymmetry, how it is possible that the former couple to leptons and quarks proportionately to g or g', and the latter proportionately to gsub(F)sup(1/2) m (fermions). The paradox is solved as follows: when the Higgs bosons are described by massive gauge superfields, the lagrangian density is non-polynomial and field redefinitions have to be performed, in particular: lepton or quark field -> lepton or quark field + (approx.= Gsub(F)sup(1/2) Higgs field) (lepton or quark field). They automatically regenerate, from the lepton and quark supersymmetric mass terms, the correct Yukawa couplings of Higgs bosons proportional to fermion masses. We also apply this method to the case in which an extra U(1) group is gauged, the standard Higgs boson h 0 being then the superpartner of the new neutral gauge boson U. (orig.)
Higgs boson production A comparison of parton showers and resummation
Balázs, C; Puljak, I
2001-01-01
The search for the Higgs boson(s) is one of the major priorities at the upgraded Fermilab Tevatron and at the CERN Large Hadron Collider (LHC). Monte Carlo (MC) event generators are heavily utilized to extract and interpret the Higgs signal, which depends on the details of the soft-gluon emission from the initial state partons in hadronic collisions. Thus, it is crucial to establish the reliability of the MC event generators used by the experimentalists. In this paper, the MC based parton shower formalism is compared to that of an analytic resummation calculation. Theoretical input, predictions and, where they exist, data for the transverse momentum distribution of Higgs bosons, Z/sup 0/ bosons, and photon pairs are compared for the Tevatron and the LHC. This comparison is useful in understanding the strengths and the weaknesses of the different theoretical approaches, and in testing their reliability. (36 refs).
Interference of identical particles from entanglement to boson-sampling
International Nuclear Information System (INIS)
Tichy, Malte C
2014-01-01
Progress in the reliable preparation, coherent propagation and efficient detection of many-body states has recently brought collective quantum phenomena of many identical particles into the spotlight. This tutorial introduces the physics of many-boson and many-fermion interference required for the description of current experiments and for the understanding of novel approaches to quantum computing. The field is motivated via the two-particle case, for which the uncorrelated, classical dynamics of distinguishable particles is compared to the quantum behaviour of identical bosons and fermions. Bunching of bosons is opposed to anti-bunching of fermions, while both species constitute equivalent sources of bipartite two-level entanglement. The realms of indistinguishable and distinguishable particles are connected by a monotonic transition, on a scale defined by the coherence length of the interfering particles. As we move to larger systems, any attempt to understand many particles via the two-particle paradigm fails: in contrast to two-particle bunching and anti-bunching, the very same signatures can be exhibited by bosons and fermions, and coherent effects dominate over statistical behaviour. The simulation of many-boson interference, termed boson-sampling, entails a qualitatively superior computational complexity when compared to fermions. The problem can be tamed by an artificially designed symmetric instance, which allows a systematic understanding of coherent bosonic and fermionic signatures for arbitrarily large particle numbers, and a means to stringently assess many-particle interference. The hierarchy between bosons and fermions also characterizes multipartite entanglement generation, for which bosons again clearly outmatch fermions. Finally, the quantum-to-classical transition between many indistinguishable and many distinguishable particles features non-monotonic structures, which dismisses the single-particle coherence length as unique indicator for
Perceptions of healthy eating in transitional phases of life
DEFF Research Database (Denmark)
Bech-Larsen, Tino; Kazbare, Laura
2014-01-01
). Originality/value - The study and findings reported in this article contribute by providing the first steps towards a better understanding of how social cognition and self-efficacy perceptions related to healthy eating develop in the transitional phases of adolescence and older adulthood. In order...... adolescents’ and older adults’ own perceptions of the barriers and facilitators of a change towards healthier eating. Design/methodology/approach - This study design consisted of four focus groups that were conducted with adolescents and older adults to identify their health orientations, and their expected...... and experienced outcomes and self-efficacies in implementing approach and avoidance behaviours in relation to healthy eating, i.e. increasing consumption of fruit and vegetables and decreasing consumption of soft drinks and red meat. Findings - The study resulted in a number of interesting insights, e...
International Nuclear Information System (INIS)
Peotta, Sebastiano; Mazza, Leonardo; Fazio, Rosario; Rossini, Davide; Vicari, Ettore; Polini, Marco
2014-01-01
Using the density-matrix renormalization group algorithm (DMRG) and a finite-size scaling analysis, we study the properties of the one-dimensional completely anisotropic spin-1/2 XYZ model with Dzyaloshinsky-Moriya (DM) interactions. The model shows a rich phase diagram: depending on the value of the coupling constants, the system can display different kinds of ferromagnetic order and Luttinger liquid behavior. Transitions from ferromagnetic to Luttinger liquid phases are first order. We thoroughly discuss the transition between different ferromagnetic phases, which, in the absence of DM interactions, belongs to the XX universality class. We provide evidence that the DM exchange term splits this critical line into two separated Ising-like transitions and that in between a disordered phase may appear. Our study sheds light on the general problem of strongly interacting spin–orbit-coupled bosonic gases trapped in an optical lattice and can be used to characterize the topological properties of superconducting nanowires in the presence of an imposed supercurrent and of interactions. (paper)
γ-unstable nuclei in the sdg boson model
International Nuclear Information System (INIS)
Kuyucak, S.; Lac, V-S.; Morrison, I.; Barret, B.R.
1991-01-01
Following the recent Pt(p,p') experiments which indicated the need for g bosons to reproduce the E4 data, we have extended the O(6) limit of the sd boson model to the sdg bosons. It is shown that a γ-unstable Hamiltonian in the sdg model consisting of a quadrupole interaction and a g boson energy leads to results that are very similar to the O(6) limit. Deviations from the empirical energy spectrum that stem from the γ-unstable nature of the Hamiltonian can be improved by including a consistent hexadecapole interaction which induces triaxiality. The same hexadecapole operator can also account for the strong E4 transitions to the 4 + states presumed to be g boson states. Specific applications are made to the Xe and Pt isotopes. 12 refs., 2 tabs., 4 figs
Field-control, phase-transitions, and life’s emergence
Directory of Open Access Journals (Sweden)
Gargi eMitra-Delmotte
2012-10-01
Full Text Available Instances of critical-like characteristics in living systems at each organizational level (bio-molecules to ecosystems as well as the spontaneous emergence of computation (Langton, do suggest the relevance of self-organized criticality (SOC. But extrapolating complex bio-systems to life’s origins, brings up a paradox: how could simple organics-- lacking the ‘soft matter’ response properties of today’s complex bio-molecules--have dissipated energy from primordial reactions (eventually reducing CO2 in a controlled manner for their ‘ordering’? Nevertheless, a causal link of life’s macroscopic irreversible dynamics to the microscopic reversible laws of statistical mechanics is indicated via the ‘functional-takeover’ of a soft magnetic scaffold by organics (c.f. Cairns-Smith’s crystal-scaffold. A field-controlled structure offers a mechanism for bootstrapping-- bottom-up assembly with top-down control: its super-paramagnetic colloidal components obey reversible dynamics, but its dissipation of magnetic (H-field energy for aggregation breaks time-reversal symmetry. The responsive adjustments of the controlled (host mineral system to environmental changes would bring about mutual coupling between random organic sets supported by it; here the generation of long-range correlations within organic (guest networks could include SOC-like mechanisms. And, such cooperative adjustments enable the selection of the functional configuration by altering the inorganic dipolar network’s capacity to assist a spontaneous process. A non-equilibrium dynamics could now drive the kinetically-oriented system (trimming the phase-space via sterically-coupled organics towards a series of phase-transitions with appropriate organic replacements taking-over its functions. Where available, experiments are cited in support of these speculations and for designing appropriate tests.
Lie-algebraic classification of effective theories with enhanced soft limits
Bogers, Mark P.; Brauner, Tomáš
2018-05-01
A great deal of effort has recently been invested in developing methods of calculating scattering amplitudes that bypass the traditional construction based on Lagrangians and Feynman rules. Motivated by this progress, we investigate the long-wavelength behavior of scattering amplitudes of massless scalar particles: Nambu-Goldstone (NG) bosons. The low-energy dynamics of NG bosons is governed by the underlying spontaneously broken symmetry, which likewise allows one to bypass the Lagrangian and connect the scaling of the scattering amplitudes directly to the Lie algebra of the symmetry generators. We focus on theories with enhanced soft limits, where the scattering amplitudes scale with a higher power of momentum than expected based on the mere existence of Adler's zero. Our approach is complementary to that developed recently in ref. [1], and in the first step we reproduce their result. That is, as far as Lorentz-invariant theories with a single physical NG boson are concerned, we find no other nontrivial theories featuring enhanced soft limits beyond the already well-known ones: the Galileon and the Dirac-Born-Infeld (DBI) scalar. Next, we show that in a certain sense, these theories do not admit a nontrivial generalization to non-Abelian internal symmetries. Namely, for compact internal symmetry groups, all NG bosons featuring enhanced soft limits necessarily belong to the center of the group. For noncompact symmetry groups such as the ISO( n) group featured by some multi-Galileon theories, these NG bosons then necessarily belong to an Abelian normal subgroup. The Lie-algebraic consistency constraints admit two infinite classes of solutions, generalizing the known multi-Galileon and multi-flavor DBI theories.
International Nuclear Information System (INIS)
Dedes, A.; Heinemeyer, S.; Su, S.; Weiglein, G.
2003-01-01
We investigate the physics of the lightest CP-even MSSM Higgs boson at the Tevatron, the LHC, a linear e + e - collider, a γγ collider and a μ + μ - collider. The analysis is performed in the three most prominent soft SUSY-breaking scenarios, mSUGRA, mGMSB and mAMSB. For all colliders the observability and parameter regions with suppressed production cross sections (compared to a SM Higgs boson with the same mass) are investigated. For the lepton and photon colliders the potential is analyzed of precision measurements of the branching ratios of the light CP-even Higgs boson for obtaining indirect bounds on the mass of the CP-odd Higgs boson and the high-energy parameters of the soft SUSY-breaking scenarios. In regions of the parameter space where the LHC can detect the heavy Higgs bosons, precision measurements of the properties of the light Higgs boson at the linear collider can provide valuable information for distinguishing between the mSUGRA, mGMSB and mAMSB scenarios
The quantum phase-transitions of water
Fillaux, François
2017-08-01
It is shown that hexagonal ices and steam are macroscopically quantum condensates, with continuous spacetime-translation symmetry, whereas liquid water is a quantum fluid with broken time-translation symmetry. Fusion and vaporization are quantum phase-transitions. The heat capacities, the latent heats, the phase-transition temperatures, the critical temperature, the molar volume expansion of ice relative to water, as well as neutron scattering data and dielectric measurements are explained. The phase-transition mechanisms along with the key role of quantum interferences and that of Hartley-Shannon's entropy are enlightened. The notions of chemical bond and force-field are questioned.
Phase transition in SO(3) gauge theory
International Nuclear Information System (INIS)
Datta, Saumen; Gavai, Rajiv V.
1998-01-01
The phase transition in SO(3) lattice gauge theory is investigated by Monte Carlo techniques with a view (i) to understand the relationship between the bulk transition and the deconfinement transition, and (ii) to resolve the current ambiguity about the nature of the high temperature phase. By introduction of a magnetic field, it was shown that the +ve and -ve values of a > correspond to the same phase. Studies on different sized lattices lead to the conclusion that in SO(3), there is only one transition, which is deconfining in nature. (author)
What's new with the electroweak phase transition?
Laine, M.
1999-01-01
We review the status of non-perturbative lattice studies of the electroweak phase transition. In the Standard Model, the complete phase diagram has been reliably determined, and the conclusion is that there is no phase transition at all for the experimentally allowed Higgs masses. In the Minimal Supersymmetric Standard Model (MSSM), in contrast, there can be a strong first order transition allowing for baryogenesis. Finally, we point out possibilities for future simulations, such as the problem of CP-violation at the MSSM electroweak phase boundary.
Microgravity Two-Phase Flow Transition
Parang, M.; Chao, D.
1999-01-01
Two-phase flows under microgravity condition find a large number of important applications in fluid handling and storage, and spacecraft thermal management. Specifically, under microgravity condition heat transfer between heat exchanger surfaces and fluids depend critically on the distribution and interaction between different fluid phases which are often qualitatively different from the gravity-based systems. Heat transfer and flow analysis in two-phase flows under these conditions require a clear understanding of the flow pattern transition and development of appropriate dimensionless scales for its modeling and prediction. The physics of this flow is however very complex and remains poorly understood. This has led to various inadequacies in flow and heat transfer modeling and has made prediction of flow transition difficult in engineering design of efficient thermal and flow systems. In the present study the available published data for flow transition under microgravity condition are considered for mapping. The transition from slug to annular flow and from bubbly to slug flow are mapped using dimensionless variable combination developed in a previous study by the authors. The result indicate that the new maps describe the flow transitions reasonably well over the range of the data available. The transition maps are examined and the results are discussed in relation to the presumed balance of forces and flow dynamics. It is suggested that further evaluation of the proposed flow and transition mapping will require a wider range of microgravity data expected to be made available in future studies.
Wilson loop's phase transition probed by non-local observable
Directory of Open Access Journals (Sweden)
Hui-Ling Li
2018-04-01
Full Text Available In order to give further insights into the holographic Van der Waals phase transition, it would be of great interest to investigate the behavior of Wilson loop across the holographic phase transition for a higher dimensional hairy black hole. We offer a possibility to proceed with a numerical calculation in order to discussion on the hairy black hole's phase transition, and show that Wilson loop can serve as a probe to detect a phase structure of the black hole. Furthermore, for a first order phase transition, we calculate numerically the Maxwell's equal area construction; and for a second order phase transition, we also study the critical exponent in order to characterize the Wilson loop's phase transition.
Ultracold atoms in one-dimensional optical lattices approaching the Tonks-Girardeau regime
International Nuclear Information System (INIS)
Pollet, L.; Rombouts, S.M.A.; Denteneer, P.J. H.
2004-01-01
Recent experiments on ultracold atomic alkali gases in a one-dimensional optical lattice have demonstrated the transition from a gas of soft-core bosons to a Tonks-Girardeau gas in the hard-core limit, where one-dimensional bosons behave like fermions in many respects. We have studied the underlying many-body physics through numerical simulations which accommodate both the soft-core and hard-core limits in one single framework. We find that the Tonks-Girardeau gas is reached only at the strongest optical lattice potentials. Results for slightly higher densities, where the gas develops a Mott-like phase already at weaker optical lattice potentials, show that these Mott-like short-range correlations do not enhance the convergence to the hard-core limit
Problem-Solving Phase Transitions During Team Collaboration.
Wiltshire, Travis J; Butner, Jonathan E; Fiore, Stephen M
2018-01-01
Multiple theories of problem-solving hypothesize that there are distinct qualitative phases exhibited during effective problem-solving. However, limited research has attempted to identify when transitions between phases occur. We integrate theory on collaborative problem-solving (CPS) with dynamical systems theory suggesting that when a system is undergoing a phase transition it should exhibit a peak in entropy and that entropy levels should also relate to team performance. Communications from 40 teams that collaborated on a complex problem were coded for occurrence of problem-solving processes. We applied a sliding window entropy technique to each team's communications and specified criteria for (a) identifying data points that qualify as peaks and (b) determining which peaks were robust. We used multilevel modeling, and provide a qualitative example, to evaluate whether phases exhibit distinct distributions of communication processes. We also tested whether there was a relationship between entropy values at transition points and CPS performance. We found that a proportion of entropy peaks was robust and that the relative occurrence of communication codes varied significantly across phases. Peaks in entropy thus corresponded to qualitative shifts in teams' CPS communications, providing empirical evidence that teams exhibit phase transitions during CPS. Also, lower average levels of entropy at the phase transition points predicted better CPS performance. We specify future directions to improve understanding of phase transitions during CPS, and collaborative cognition, more broadly. Copyright © 2017 Cognitive Science Society, Inc.
Late-time cosmological phase transitions
International Nuclear Information System (INIS)
Schramm, D.N.
1990-11-01
It is shown that the potential galaxy formation and large-scale structure problems of objects existing at high redshifts (Z approx-gt 5), structures existing on scales of 100M pc as well as velocity flows on such scales, and minimal microwave anisotropies (ΔT/T) approx-lt 10 -5 can be solved if the seeds needed to generate structure form in a vacuum phase transition after decoupling. It is argued that the basic physics of such a phase transition is no more exotic than that utilized in the more traditional GUT scale phase transitions, and that, just as in the GUT case, significant random gaussian fluctuations and/or topological defects can form. Scale lengths of ∼100M pc for large-scale structure as well as ∼1 M pc for galaxy formation occur naturally. Possible support for new physics that might be associated with such a late-time transition comes from the preliminary results of the SAGE solar neutrino experiment, implying neutrino flavor mixing with values similar to those required for a late-time transition. It is also noted that a see-saw model for the neutrino masses might also imply a tau neutrino mass that is an ideal hot dark matter candidate. However, in general either hot or cold dark matter can be consistent with a late-time transition. 47 refs., 2 figs
gamma. -unstable nuclei in the sdg boson model
Energy Technology Data Exchange (ETDEWEB)
Kuyucak, S.; Lac, V.S.; Morrison, I.; Barrett, B.R. (School of Physics, Univ. of Melbourne, Parkville (Australia))
1991-07-18
Following the recent Pt(p, p') experiments which indicated the need for g bosons to reproduce the E4 data, we have extended the O(6) limit of the sd boson model to include g bosons. It is shown that a {gamma}-unstable hamiltonian in the sdg model consisting of a quadrupole interaction and a g boson energy leads to results that are very similar to the O(6) limit. Deviations from the empirical energy spectrum that stem from the {gamma}-unstable nature of the hamiltonian can be improved by including a consistent hexadecapole interaction which induces triaxiality. The same hexadecapole operator can also account for the strong E4 transitions. Applications are made to the Xe and Pt isotopes. (orig.).
γ-unstable nuclei in the sdg boson model
Kuyucak, S.; Lac, V.-S.; Morrison, I.; Barrett, B. R.
1991-07-01
Following the recent Pt(p, p‧) experiments which indicated the need for g bosons to reproduce the E4 data, we have extended the O(6) limit of the sd boson model to include g bosons. It is shown that a γ-unstable hamiltonian in the sdg model consisting of a quadrupole interaction and a g boson energy leads to results that are very similar to the O(6) limit. Deviations from the empirical energy spectrum that stem from the γ-unstable nature of the hamiltonian can be improved by including a consistent hexadecapole interaction which induces triaxiality. The same hexadecapole operator can also account for the strong E4 transitions. Applications are made to the Xe and Pt isotopes.
Sajna, A. S.; Polak, T. P.
2018-06-01
Gauge potentials with different configurations have been recently realized in the optical lattice experiments. It is remarkable that one of the simplest gauge potential can generate particle energy spectrum with the self-similar structure known as a Hofstadter butterfly. We investigate theoretically the impact of strong on-site interaction on such a spectrum in the bosonic Mott insulator within Bose-Hubbard model. In particular, it is shown that the fractal structure is encoded in the quasi-particle and hole bosonic branches for different lattice backgrounds. For example a square lattice and other structures (brick-wall and staggered magnetic flux lattice) which contain Dirac points in energy dispersions are considered. This shows that single-particle physics is still present even in the strong interaction limit for whole Hofstadter spectrum. Additionally we observe, that although in brick-wall and staggered flux lattices the quasi-particle densities of states look qualitatively similar, the corresponding Hofstadter butterfly assumes different forms. In particular, we use a superposition of two different synthetic gauge fields which appears to be a generator of non-trivial phenomena in the optical lattice systems. We also discuss the consequences of these phenomena on the phase diagrams between bosonic Mott insulator and superfluid phase. The analysis is carried out within the strong coupling expansion method on the finite size lattices and also at finite temperatures which are relevant for the currently made experiments.
Comparing several boson mappings with the shell model
International Nuclear Information System (INIS)
Menezes, D.P.; Yoshinaga, Naotaka; Bonatsos, D.
1990-01-01
Boson mappings are an essential step in establishing a connection between the successful phenomenological interacting boson model and the shell model. The boson mapping developed by Bonatsos, Klein and Li is applied to a single j-shell and the resulting energy levels and E2 transitions are shown for a pairing plus quadrupole-quadrupole Hamiltonian. The results are compared to the exact shell model calculation, as well as to these obtained through use of the Otsuka-Arima-Iachello mapping and the Zirnbauer-Brink mapping. In all cases good results are obtained for the spherical and near-vibrational cases
Jankowska-Sumara, Irena; Ko, Jae-Hyeon; Podgórna, Maria; Oh, Soo Han; Majchrowski, Andrzej
2017-09-01
Raman light scattering was used to detect the sequence of transitions in a PbHf1-xSnxO3 (PHS) single crystal with x = 0.30 in a temperature range of 77-873 K. Changes of Raman spectra were observed in the vicinity of structural phase transitions: between the antiferroelectric (AFE1)-antiferroelectric (AFE2)—intermediate—paraelectric phases. Light scattering and dielectric investigations were used to find out the nature and sequence of the phase transition, as well as the large dielectric permittivity values measured at the phase transition, by searching for the soft-phonon-mode behavior. The experimentally recorded spectra were analyzed in terms of the damped-harmonic oscillator model for the phonon bands. It is demonstrated that the structural phase transformations in PHS can be considered as the result of softening of many modes, not only the ferroelectric one. It was also proved that locally broken symmetry effects are present at temperatures far above the Curie temperature and are connected with the softening of two optic modes of different nature.
Phase transitions and neutron scattering
International Nuclear Information System (INIS)
Shirane, G.
1993-01-01
A review is given of recent advances in neutron scattering studies of solid state physics. I have selected the study of a structural phase transition as the best example to demonstrate the power of neutron scattering techniques. Since energy analysis is relatively easy, the dynamical aspects of a transition can be elucidated by the neutron probe. I shall discuss in some detail current experiments on the 100 K transition in SrTiO 3 , the crystal which has been the paradigm of neutron studies of phase transitions for many years. This new experiment attempts to clarify the relation between the neutron central peak, observed in energy scans, and the two length scales observed in recent x-ray diffraction studies where only scans in momentum space are possible. (author)
Quantum phase transitions in random XY spin chains
International Nuclear Information System (INIS)
Bunder, J.E.; McKenzie, R.H.
2000-01-01
Full text: The XY spin chain in a transverse field is one of the simplest quantum spin models. It is a reasonable model for heavy fermion materials such as CeCu 6-x Au x . It has two quantum phase transitions: the Ising transition and the anisotropic transition. Quantum phase transitions occur at zero temperature. We are investigating what effect the introduction of randomness has on these quantum phase transitions. Disordered systems which undergo quantum phase transitions can exhibit new universality classes. The universality class of a phase transition is defined by the set of critical exponents. In a random system with quantum phase transitions we can observe Griffiths-McCoy singularities. Such singularities are observed in regions which have no long range order, so they are not classified as critical regions, yet they display phenomena normally associated with critical points, such as a diverging susceptibility. Griffiths-McCoy phases are due to rare regions with stronger than! average interactions and may be present far from the quantum critical point. We show how the random XY spin chain may be mapped onto a random Dirac equation. This allows us to calculate the density of states without making any approximations. From the density of states we can describe the conditions which should allow a Griffiths-McCoy phase. We find that for the Ising transition the dynamic critical exponent, z, is not universal. It is proportional to the disorder strength and inversely proportional to the energy gap, hence z becomes infinite at the critical point where the energy gap vanishes
Analytical calculation of the vibrator-rotor transition in the sdg interacting boson model
International Nuclear Information System (INIS)
Wang Baolin
1992-01-01
Analytical calculation of the vibrator-rotor transition is given by utilizing the 1/N expansion technique in the sdg IBM. The phase transition of low-lying energy spectrum and E2 transition for Sm isotopes are calculated
Phase transition phenomenon: A compound measure analysis
Kang, Bo Soo; Park, Chanhi; Ryu, Doojin; Song, Wonho
2015-06-01
This study investigates the well-documented phenomenon of phase transition in financial markets using combined information from both return and volume changes within short time intervals. We suggest a new measure for the phase transition behaviour of markets, calculated as a return distribution conditional on local variance in volume imbalance, and show that this measure successfully captures phase transition behaviour under various conditions. We analyse the intraday trade and quote dataset from the KOSPI 200 index futures, which includes detailed information on the original order size and the type of each initiating investor. We find that among these two competing factors, the submitted order size yields more explanatory power on the phenomenon of market phase transition than the investor type.
Energy Technology Data Exchange (ETDEWEB)
Shaginyan, V.R., E-mail: vrshag@thd.pnpi.spb.r [Petersburg Nuclear Physics Institute, RAS, Gatchina 188300 (Russian Federation); Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Amusia, M.Ya. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Popov, K.G. [Komi Science Center, Ural Division, RAS, Syktyvkar 167982 (Russian Federation)
2010-01-11
Low-temperature specific-heat measurements on YbRh{sub 2}Si{sub 2} at the second order antiferromagnetic (AF) phase transition reveal a sharp peak at T{sub N}=72 mK. The corresponding critical exponent alpha turns out to be alpha=0.38, which differs significantly from that obtained within the framework of the fluctuation theory of second order phase transitions based on the scale invariance, where alphaapprox =0.1. We show that under the application of magnetic field the curve of the second order AF phase transitions passes into a curve of the first order ones at the tricritical point leading to a violation of the critical universality of the fluctuation theory. This change of the phase transition is generated by the fermion condensation quantum phase transition. Near the tricritical point the Landau theory of second order phase transitions is applicable and gives alphaapprox =1/2. We demonstrate that this value of alpha is in good agreement with the specific-heat measurements.
Toleddano, J.C.; Glazer, A.M.; Hahn, Th.; Parthe, E.; Roth, R.S.; Berry, R.S.; Metselaar, R.; Abrahams, S.C.
1998-01-01
A compact and intuitive nomenclature is recommended for naming each phase formed by a given material in a sequence of phase transitions as a function of temperature and/or pressure. The most commonly used label for each phase in a sequence, such as [alpha], [beta], ..., I, II, ... etc., is included
A Soft-Inflatable Exosuit for Knee Rehabilitation: Assisting Swing Phase During Walking
Directory of Open Access Journals (Sweden)
Saivimal Sridar
2018-05-01
Full Text Available In this paper, we present a soft-inflatable exosuit to assist knee extension during gait training for stroke rehabilitation. The soft exosuit is designed to provide 25% of the knee moment required during the swing phase of the gait cycle and is integrated with inertial measurement units (IMUs and smart shoe insole sensors to improve gait phase detection and controller design. The stiffness of the knee joint during level walking is computed using inverse dynamics. The soft-inflatable actuators, with an I cross-section, are mechanically characterized at varying angles to enable generation of the required stiffness outputs. A linear relation between the inflatable actuator stiffness and internal pressure as a function of the knee angle is obtained, and a two-layer stiffness controller is implemented to assist the knee joint by providing appropriate stiffness during the swing phase. Finally, to evaluate the ability of the exosuit to assist in swing motion, surface-electromyography (sEMG sensors are placed on the three muscle groups of the quadriceps and two groups of the hamstrings, on three healthy participants. A reduction in muscle activity of the rectus femoris, vastus lateralis, and vastus medialis is observed, which demonstrates feasibility of operation and potential future usage of the soft inflatable exosuit by impaired users.
The Structural Phase Transition in Octaflournaphtalene
DEFF Research Database (Denmark)
Mackenzie, Gordon A.; Arthur, J. W.; Pawley, G. S.
1977-01-01
The phase transition in octafluoronaphthalene has been investigated by Raman scattering and neutron powder diffraction. The weight of the experimental evidence points to a unit cell doubling in the a direction, but with no change in space group symmetry. Lattice dynamics calculations support...... this evidence and indicate that the mechanism of the phase transition may well be the instability of a zone boundary acoustic mode of librational character. The structure of the low-temperature phase has been refined and the Raman spectra of the upper and lower phases are reported....
Unconventional phase transitions in a constrained single polymer chain
International Nuclear Information System (INIS)
Klushin, L I; Skvortsov, A M
2011-01-01
Phase transitions were recognized among the most fascinating phenomena in physics. Exactly solved models are especially important in the theory of phase transitions. A number of exactly solved models of phase transitions in a single polymer chain are discussed in this review. These are three models demonstrating the second order phase transitions with some unusual features: two-dimensional model of β-structure formation, the model of coil–globule transition and adsorption of a polymer chain grafted on the solid surface. We also discuss models with first order phase transitions in a single macromolecule which admit not only exact analytical solutions for the partition function with explicit finite-size effects but also the non-equilibrium free energy as a function of the order parameter (Landau function) in closed analytical form. One of them is a model of mechanical desorption of a macromolecule, which demonstrates an unusual first order phase transition with phase coexistence within a single chain. Features of first and second order transitions become mixed here due to phase coexistence which is not accompanied by additional interfacial free energy. Apart from that, there exist several single-chain models belonging to the same class (adsorption of a polymer chain tethered near the solid surface or liquid–liquid interface, and escape transition upon compressing a polymer between small pistons) that represent examples of a highly unconventional first order phase transition with several inter-related unusual features: no simultaneous phase coexistence, and hence no phase boundary, non-concave thermodynamic potential and non-equivalence of conjugate ensembles. An analysis of complex zeros of partition functions upon approaching the thermodynamic limit is presented for models with and without phase coexistence. (topical review)
Quantum phase transitions in semilocal quantum liquids
Iqbal, Nabil; Liu, Hong; Mezei, Márk
2015-01-01
We consider several types of quantum critical phenomena from finite-density gauge-gravity duality which to different degrees lie outside the Landau-Ginsburg-Wilson paradigm. These include: (i) a "bifurcating" critical point, for which the order parameter remains gapped at the critical point, and thus is not driven by soft order parameter fluctuations. Rather it appears to be driven by "confinement" which arises when two fixed points annihilate and lose conformality. On the condensed side, there is an infinite tower of condensed states and the nonlinear response of the tower exhibits an infinite spiral structure; (ii) a "hybridized" critical point which can be described by a standard Landau-Ginsburg sector of order parameter fluctuations hybridized with a strongly coupled sector; (iii) a "marginal" critical point which is obtained by tuning the above two critical points to occur together and whose bosonic fluctuation spectrum coincides with that postulated to underly the "Marginal Fermi Liquid" description of the optimally doped cuprates.
Efficiency analysis on a two-level three-phase quasi-soft-switching inverter
DEFF Research Database (Denmark)
Geng, Pan; Wu, Weimin; Huang, Min
2013-01-01
When designing an inverter, an engineer often needs to select and predict the efficiency beforehand. For the standard inverters, plenty of researches are analyzing the power losses and also many software tools are being used for efficiency calculation. In this paper, the efficiency calculation...... for non-conventional inverters with special shoot-through state is introduced and illustrated through the analysis on a special two-level three-phase quasi-soft-switching inverter. Efficiency comparison between the classical two-stage two-level three-phase inverter and the two-level three-phase quasi......-soft-switching inverter is carried out. A 10 kW/380 V prototype is constructed to verify the analysis. The experimental results show that the efficiency of the new inverter is higher than that of the traditional two-stage two- level three-phase inverter....
Lee, Ki Hoon; Lee, Changhee; Jeong, Jae-Seung; Min, Hongki; Chung, Suk Bum
For the quantum well in an optical microcavity, the interplay of the Coulomb interaction and the electron-photon coupling can lead to the emergence of bosonic quasiparticles consisting of the exciton and the cavity photon known as polariton, which can form the Bose-Einstein condensate above a threshold density. Additional physics due to the nontrivial Berry phase comes into play when the quantum well consists of the gapped Dirac material such as the transition metal dichalcogenide (TMD) MoS2 or WTe2. Specifically, in forming excitons, the electron-photon coupling from the optical selection rule due to the Berry phase competes against, rather than cooperates with, the Coulomb interaction. We find that this competition gives rise to the spontaneous breaking of the rotational symmetry in the polariton condensate and also drives topological phase transition, both novel features in polariton condensation. We also investigate the possible detection of this competition through photoluminescence. This work was supported in part by the Institute for Basic Science of Korea (IBS) under Grant IBS-R009-Y1 and by the National Research Foundation of Korea (NRF) under the Basic Science Research Program Grant No. 2015R1D1A1A01058071.
Stochastic differential equations for quantum dynamics of spin-boson networks
International Nuclear Information System (INIS)
Mandt, Stephan; Sadri, Darius; Houck, Andrew A; Türeci, Hakan E
2015-01-01
A popular approach in quantum optics is to map a master equation to a stochastic differential equation, where quantum effects manifest themselves through noise terms. We generalize this approach based on the positive-P representation to systems involving spin, in particular networks or lattices of interacting spins and bosons. We test our approach on a driven dimer of spins and photons, compare it to the master equation, and predict a novel dynamic phase transition in this system. Our numerical approach has scaling advantages over existing methods, but typically requires regularization in terms of drive and dissipation. (paper)
Soft Expansion of Double-Real-Virtual Corrections to Higgs Production at N$^3$LO
Anastasiou, Charalampos; Dulat, Falko; Furlan, Elisabetta; Herzog, Franz; Mistlberger, Bernhard
2015-01-01
We present methods to compute higher orders in the threshold expansion for the one-loop production of a Higgs boson in association with two partons at hadron colliders. This process contributes to the N$^3$LO Higgs production cross section beyond the soft-virtual approximation. We use reverse unitarity to expand the phase-space integrals in the small kinematic parameters and to reduce the coefficients of the expansion to a small set of master integrals. We describe two methods for the calculation of the master integrals. The first was introduced for the calculation of the soft triple-real radiation relevant to N$^3$LO Higgs production. The second uses a particular factorization of the three body phase-space measure and the knowledge of the scaling properties of the integral itself. Our result is presented as a Laurent expansion in the dimensional regulator, although some of the master integrals are computed to all orders in this parameter.
Phase transitions and baryogenesis from decays
Shuve, Brian; Tamarit, Carlos
2017-10-01
We study scenarios in which the baryon asymmetry is generated from the decay of a particle whose mass originates from the spontaneous breakdown of a symmetry. This is realized in many models, including low-scale leptogenesis and theories with classical scale invariance. Symmetry breaking in the early universe proceeds through a phase transition that gives the parent particle a time-dependent mass, which provides an additional departure from thermal equilibrium that could modify the efficiency of baryogenesis from out-of-equilibrium decays. We characterize the effects of various types of phase transitions and show that an enhancement in the baryon asymmetry from decays is possible if the phase transition is of the second order, although such models are typically fine-tuned. We also stress the role of new annihilation modes that deplete the parent particle abundance in models realizing such a phase transition, reducing the efficacy of baryogenesis. A proper treatment of baryogenesis in such models therefore requires the inclusion of the effects we study in this paper.
Sound speed during the QCD phase transition
International Nuclear Information System (INIS)
Nagasawa, Michiyasu; Yokoyama, Jun'ichi
1998-01-01
The Jeans scale is estimated during the coexistence epoch of quark-gluon and hadron phases in the first-order QCD phase transition. It is shown that, contrary to previous claims, reduction of the sound speed is so little that the phase transition does not affect evolution of cosmological density fluctuations appreciably. (author)
International Nuclear Information System (INIS)
Yu Zengqiang; Zhai Hui; Zhang Shizhong
2011-01-01
We study the properties of dilute bosons immersed in a single-component Fermi sea across a broad boson-fermion Feshbach resonance. The stability of the mixture requires that the bare interaction between bosons exceeds a critical value, which is a universal function of the boson-fermion scattering length, and exhibits a maximum in the unitary region. We calculate the quantum depletion, momentum distribution, and the boson contact parameter across the resonance. The transition from condensate to molecular Fermi gas is also discussed.
Boosted Higgs boson tagging using jet substructures
Shvydkin, Pavel
2016-01-01
Searching BSM particles via the Higgs boson final state has now become common. The mass of desired BSM particle is more than 1 TeV, thereby its decay products are highly Lorentz-boosted. Hence the jets from b quark-antiquark pair - which the Higgs boson mostly decays into - are very closed to each other, and merged into one jet, that is typically reconstructed using large jet sizes (∆R = 0.8). In this work regression technique is applied to AK8 jets (which defined by anti-kT algorithm, using ΔR = 0.8). The regression makes use of boosted jets with substructure information, coupled with the pecularities of a b quark decay, like the presence of a soft lepton (SL) inside the jet. It has allowed to improve the resolution of the mass reconstruction and transverse momentum of the Higgs boson. This application results in improvement of the mass reconstruction by 3-4 percent. These result may be improved firstly by making more careful pileup rejection. Then it is possible to combine base regression train for dif...
Phase transition of aragonite in abalone nacre
An, Yuanlin; Liu, Zhiming; Wu, Wenjian
2013-04-01
Nacre is composed of about 95 vol.% aragonite and 5 vol.% biopolymer and famous for its "brick and mortar" microstructure. The phase transition temperature of aragonite in nacre is lower than the pure aragonite. In situ XRD was used to identify the phase transition temperature from aragonite to calcite in nacre, based on the analysis of TG-DSC of fresh nacre and demineralized nacre. The results indicate that the microstructure and biopolymer are the two main factors that influence the phase transition temperature of aragonite in nacre.
Mixed-order phase transition in a colloidal crystal
Alert, Ricard; Tierno, Pietro; Casademunt, Jaume
2017-12-01
Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid-solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field H. At the transition field Hs, the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length ξ∝|H2-Hs2|-1/2. Mean-field critical exponents are predicted, since the upper critical dimension of the transition is du=2. Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.
Mixed-order phase transition in a colloidal crystal.
Alert, Ricard; Tierno, Pietro; Casademunt, Jaume
2017-12-05
Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid-solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field [Formula: see text] At the transition field [Formula: see text], the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length [Formula: see text] Mean-field critical exponents are predicted, since the upper critical dimension of the transition is [Formula: see text] Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.
Hamano, Katsumi; Hirotsu, Shunsuke
1980-01-01
Phenomenological equations are derived which interrelate the anomalies in various thermodynamic quantities above the transition point of a cubic-to-tetragonal phase transition caused by an instability of a triply degenerate soft mode. The anomalous part of the Gibbs free energy is assumed to be a simple sum of the three parts which represent the contributions from the three fluctuation components. A cylindrical approximation is adopted to each of the three contributions by taking into account the symmetry of the fluctuations. The theory predicts that the adiabatic elastic compliances, s11s, s12s, and also s11s-s12s should exhibit anomalies proportional to the anomaly in the specific heat at constant pressure. This is in marked contrast with the result of the generalized Pippard equations derived by Garland, and by Janovec. The new equations are successfully tested for KMnF3, CsPbCl3, and CsPbBr3. The β-γ transition of NH4Br is also discussed.
Gravitational waves from global second order phase transitions
Energy Technology Data Exchange (ETDEWEB)
Jr, John T. Giblin [Department of Physics, Kenyon College, 201 North College Rd, Gambier, OH 43022 (United States); Price, Larry R.; Siemens, Xavier; Vlcek, Brian, E-mail: giblinj@kenyon.edu, E-mail: larryp@caltech.edu, E-mail: siemens@gravity.phys.uwm.edu, E-mail: bvlcek@uwm.edu [Center for Gravitation and Cosmology, Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States)
2012-11-01
Global second-order phase transitions are expected to produce scale-invariant gravitational wave spectra. In this manuscript we explore the dynamics of a symmetry-breaking phase transition using lattice simulations. We explicitly calculate the stochastic gravitational wave background produced during the transition and subsequent self-ordering phase. We comment on this signal as it compares to the scale-invariant spectrum produced during inflation.
High temperature phase transitions without infrared divergences
International Nuclear Information System (INIS)
Tetradis, N.; Wetterich, C.
1993-09-01
The most commonly used method for the study of high temperature phase transitions is based on the perturbative evaluation of the temperature dependent effective potential. This method becomes unreliable in the case of a second order or weakly first order phase transition, due to the appearance of infrared divergences. These divergences can be controlled through the method of the effective average action which employs renormalization group ideas. We report on the study of the high temperature phase transition for the N-component φ 4 theory. A detailed quantitative picture of the second order phase transition is presented, including the critical exponents for the behaviour in the vicinity of the critical temperature. An independent check of the results is obtained in the large N limit, and contact with the perturbative approach is established through the study of the Schwinger-Dyson equations. (orig.)
Kerner, Boris S; Klenov, Sergey L; Schreckenberg, Michael
2014-05-01
Physical features of induced phase transitions in a metastable free flow at an on-ramp bottleneck in three-phase and two-phase cellular automaton (CA) traffic-flow models have been revealed. It turns out that at given flow rates at the bottleneck, to induce a moving jam (F → J transition) in the metastable free flow through the application of a time-limited on-ramp inflow impulse, in both two-phase and three-phase CA models the same critical amplitude of the impulse is required. If a smaller impulse than this critical one is applied, neither F → J transition nor other phase transitions can occur in the two-phase CA model. We have found that in contrast with the two-phase CA model, in the three-phase CA model, if the same smaller impulse is applied, then a phase transition from free flow to synchronized flow (F → S transition) can be induced at the bottleneck. This explains why rather than the F → J transition, in the three-phase theory traffic breakdown at a highway bottleneck is governed by an F → S transition, as observed in real measured traffic data. None of two-phase traffic-flow theories incorporates an F → S transition in a metastable free flow at the bottleneck that is the main feature of the three-phase theory. On the one hand, this shows the incommensurability of three-phase and two-phase traffic-flow theories. On the other hand, this clarifies why none of the two-phase traffic-flow theories can explain the set of fundamental empirical features of traffic breakdown at highway bottlenecks.
BEC-BCS crossover in a (p+ip)-wave pairing Hamiltonian coupled to bosonic molecular pairs
International Nuclear Information System (INIS)
Dunning, Clare; Isaac, Phillip S.; Links, Jon; Zhao, Shao-You
2011-01-01
We analyse a (p+ip)-wave pairing BCS Hamiltonian, coupled to a single bosonic degree of freedom representing a molecular condensate, and investigate the nature of the BEC-BCS crossover for this system. For a suitable restriction on the coupling parameters, we show that the model is integrable and we derive the exact solution by the algebraic Bethe ansatz. In this manner we also obtain explicit formulae for correlation functions and compute these for several cases. We find that the crossover between the BEC state and the strong pairing p+ip phase is smooth for this model, with no intermediate quantum phase transition.
On the zeros of the Husimi functions of the spin boson model
International Nuclear Information System (INIS)
Cibils, M.B.; Cuche, Y.; Leboeuf, P.; Wreszinski, W.F.
1992-03-01
The distribution of zeros of the Husimi functions for the spin-boson model is studied, following an approach introduced by Leboeuf and Voros. The interest lies in the model's double feature of possessing both a classical integrable to chaotic transition and an unbounded four-dimensional phase space. The latter gives rise to several new questions regarding the Husimi zeros which are discussed and partially answered. Some significant results occur in spite of the fact that the case of spin one-half is treated. (authors) 20 refs., 4 figs
Phase diagrams for an ideal gas mixture of fermionic atoms and bosonic molecules
DEFF Research Database (Denmark)
Williams, J. E.; Nygaard, Nicolai; Clark, C. W.
2004-01-01
We calculate the phase diagrams for a harmonically trapped ideal gas mixture of fermionic atoms and bosonic molecules in chemical and thermal equilibrium, where the internal energy of the molecules can be adjusted relative to that of the atoms by use of a tunable Feshbach resonance. We plot...... diagrams obtained in recent experiments on the Bose-Einstein condensation to Bardeen-Cooper-Schrieffer crossover, in which the condensate fraction is plotted as a function of the initial temperature of the Fermi gas measured before a sweep of the magnetic field through the resonance region....
Quantum Glass of Interacting Bosons with Off-Diagonal Disorder
Piekarska, A. M.; Kopeć, T. K.
2018-04-01
We study disordered interacting bosons described by the Bose-Hubbard model with Gaussian-distributed random tunneling amplitudes. It is shown that the off-diagonal disorder induces a spin-glass-like ground state, characterized by randomly frozen quantum-mechanical U(1) phases of bosons. To access criticality, we employ the "n -replica trick," as in the spin-glass theory, and the Trotter-Suzuki method for decomposition of the statistical density operator, along with numerical calculations. The interplay between disorder, quantum, and thermal fluctuations leads to phase diagrams exhibiting a glassy state of bosons, which are studied as a function of model parameters. The considered system may be relevant for quantum simulators of optical-lattice bosons, where the randomness can be introduced in a controlled way. The latter is supported by a proposition of experimental realization of the system in question.
Renormalization group approach to QCD phase transitions
International Nuclear Information System (INIS)
Midorikawa, S.; Yoshimoto, S.; So, H.
1987-01-01
Effective scalar theories for QCD are proposed to investigate the deconfining and chiral phase transitions. The orders of the phase transitions are determined by infrared stabilities of the fixed points. It is found that the transitions in SU(3) gauge theories are of 1st order for any number of massless flavors. The cases of SU(2) and SU(4) gauge theories are also discussed. (orig.)
Transition quantique entre états électroniques de systèmes bi-couche
Pasquier, Vincent
The possible phase transitions when two layers at filling factor νt=1 are gradually separated are studied in this article. In the bosonic case the system should undergo a pairing transition from a Fermi liquid to an incompressible state. In the Fermionic case, the state evolves from an incompressible (1,1,1) state to a Fermi liquid. It is speculated that there is an intermediate phase involving charge two quasiparticles. To cite this article: V. Pasquier, C. R. Physique 3 (2002) 709-715.
Phase transitions in nonequilibrium traffic theory
Energy Technology Data Exchange (ETDEWEB)
Zhang, H.M.
2000-02-01
This paper uses the center difference scheme of Lax-Friedrichs to numerically solve a newly developed continuum traffic flow theory and the kinematic theory of Lighthill and Whitham, and Richards, and it studies the flow-concentration phase transitions in flow containing both shock and rarefaction waves. A homogeneous road with finite length was modeled by both theories. Numerical simulations show that both theories yield nearly identical results for two representative Riemann problems--one has a shock solution and the other a rarefaction wave solution. Their phase transition curves, however, are different: those derived from the new theory have two branches--one for acceleration flow and one for deceleration flow, whereas those derived from the LWR theory comprise a single curve--the equilibrium curve. The phase transition curves in the shock case agree well with certain experimental observations but disagree with others. This disagreement may be resolved by studying transitions among nonequilibrium states, which awaits further development of a more accurate finite difference approximation of the nonequilibrium theory.
Dynamical quantum phase transitions: a review
Heyl, Markus
2018-05-01
Quantum theory provides an extensive framework for the description of the equilibrium properties of quantum matter. Yet experiments in quantum simulators have now opened up a route towards the generation of quantum states beyond this equilibrium paradigm. While these states promise to show properties not constrained by equilibrium principles, such as the equal a priori probability of the microcanonical ensemble, identifying the general properties of nonequilibrium quantum dynamics remains a major challenge, especially in view of the lack of conventional concepts such as free energies. The theory of dynamical quantum phase transitions attempts to identify such general principles by lifting the concept of phase transitions to coherent quantum real-time evolution. This review provides a pedagogical introduction to this field. Starting from the general setting of nonequilibrium dynamics in closed quantum many-body systems, we give the definition of dynamical quantum phase transitions as phase transitions in time with physical quantities becoming nonanalytic at critical times. We summarize the achieved theoretical advances as well as the first experimental observations, and furthermore provide an outlook to major open questions as well as future directions of research.
Dynamical quantum phase transitions: a review.
Heyl, Markus
2018-05-01
Quantum theory provides an extensive framework for the description of the equilibrium properties of quantum matter. Yet experiments in quantum simulators have now opened up a route towards the generation of quantum states beyond this equilibrium paradigm. While these states promise to show properties not constrained by equilibrium principles, such as the equal a priori probability of the microcanonical ensemble, identifying the general properties of nonequilibrium quantum dynamics remains a major challenge, especially in view of the lack of conventional concepts such as free energies. The theory of dynamical quantum phase transitions attempts to identify such general principles by lifting the concept of phase transitions to coherent quantum real-time evolution. This review provides a pedagogical introduction to this field. Starting from the general setting of nonequilibrium dynamics in closed quantum many-body systems, we give the definition of dynamical quantum phase transitions as phase transitions in time with physical quantities becoming nonanalytic at critical times. We summarize the achieved theoretical advances as well as the first experimental observations, and furthermore provide an outlook to major open questions as well as future directions of research.
Collective modes in simple melts: Transition from soft spheres to the hard sphere limit.
Khrapak, Sergey; Klumov, Boris; Couëdel, Lénaïc
2017-08-11
We study collective modes in a classical system of particles with repulsive inverse-power-law (IPL) interactions in the fluid phase, near the fluid-solid coexistence (IPL melts). The IPL exponent is varied from n = 10 to n = 100 to mimic the transition from moderately soft to hard-sphere-like interactions. We compare the longitudinal dispersion relations obtained using molecular dynamic (MD) simulations with those calculated using the quasi-crystalline approximation (QCA) and find that this simple theoretical approach becomes grossly inaccurate for [Formula: see text]. Similarly, conventional expressions for high-frequency (instantaneous) elastic moduli, predicting their divergence as n increases, are meaningless in this regime. Relations of the longitudinal and transverse elastic velocities of the QCA model to the adiabatic sound velocity, measured in MD simulations, are discussed for the regime where QCA is applicable. Two potentially useful freezing indicators for classical particle systems with steep repulsive interactions are discussed.
Application of Soft Computing in Coherent Communications Phase Synchronization
Drake, Jeffrey T.; Prasad, Nadipuram R.
2000-01-01
The use of soft computing techniques in coherent communications phase synchronization provides an alternative to analytical or hard computing methods. This paper discusses a novel use of Adaptive Neuro-Fuzzy Inference Systems (ANFIS) for phase synchronization in coherent communications systems utilizing Multiple Phase Shift Keying (MPSK) modulation. A brief overview of the M-PSK digital communications bandpass modulation technique is presented and it's requisite need for phase synchronization is discussed. We briefly describe the hybrid platform developed by Jang that incorporates fuzzy/neural structures namely the, Adaptive Neuro-Fuzzy Interference Systems (ANFIS). We then discuss application of ANFIS to phase estimation for M-PSK. The modeling of both explicit, and implicit phase estimation schemes for M-PSK symbols with unknown structure are discussed. Performance results from simulation of the above scheme is presented.
Density Functional Theory for Phase-Ordering Transitions
Energy Technology Data Exchange (ETDEWEB)
Wu, Jianzhong [Univ. of California, Riverside, CA (United States)
2016-03-30
Colloids display astonishing structural and dynamic properties that can be dramatically altered by modest changes in the solution condition or an external field. This complex behavior stems from a subtle balance of colloidal forces and intriguing mesoscopic and macroscopic phase transitions that are sensitive to the processing conditions and the dispersing environment. Whereas the knowledge on the microscopic structure and phase behavior of colloidal systems at equilibrium is now well-advanced, quantitative predictions of the dynamic properties and the kinetics of phase-ordering transitions in colloids are not always realized. Many important mesoscopic and off-equilibrium colloidal states remain poorly understood. The proposed research aims to develop a new, unifying approach to describe colloidal dynamics and the kinetics of phase-ordering transitions based on accomplishments from previous work for the equilibrium properties of both uniform and inhomogeneous systems and on novel concepts from the state-of-the-art dynamic density functional theory. In addition to theoretical developments, computational research is designed to address a number of fundamental questions on phase-ordering transitions in colloids, in particular those pertinent to a competition of the dynamic pathways leading to various mesoscopic structures, off-equilibrium states, and crystalline phases. By providing a generic theoretical framework to describe equilibrium, metastable as well as non-ergodic phase transitions concurrent with the colloidal self-assembly processes, accomplishments from this work will have major impacts on both fundamental research and technological applications.
Problem-solving phase transitions during team collaboration
DEFF Research Database (Denmark)
Wiltshire, Travis; Butner, Jonathan E.; Fiore, Stephen M.
2018-01-01
) with dynamical systems theory suggesting that when a system is undergoing a phase transition it should exhibit a peak in entropy and that entropy levels should also relate to team performance. Communications from 40 teams that collaborated on a complex problem were coded for occurrence of problem......-solving processes. We applied a sliding window entropy technique to each team's communications and specified criteria for (a) identifying data points that qualify as peaks and (b) determining which peaks were robust. We used multilevel modeling, and provide a qualitative example, to evaluate whether phases exhibit...... phases. Peaks in entropy thus corresponded to qualitative shifts in teams’ CPS communications, providing empirical evidence that teams exhibit phase transitions during CPS. Also, lower average levels of entropy at the phase transition points predicted better CPS performance. We specify future directions...
Computational advances in transition phase analysis
International Nuclear Information System (INIS)
Morita, K.; Kondo, S.; Tobita, Y.; Shirakawa, N.; Brear, D.J.; Fischer, E.A.
1994-01-01
In this paper, historical perspective and recent advances are reviewed on computational technologies to evaluate a transition phase of core disruptive accidents in liquid-metal fast reactors. An analysis of the transition phase requires treatment of multi-phase multi-component thermohydraulics coupled with space- and energy-dependent neutron kinetics. Such a comprehensive modeling effort was initiated when the program of SIMMER-series computer code development was initiated in the late 1970s in the USA. Successful application of the latest SIMMER-II in USA, western Europe and Japan have proved its effectiveness, but, at the same time, several areas that require further research have been identified. Based on the experience and lessons learned during the SIMMER-II application through 1980s, a new project of SIMMER-III development is underway at the Power Reactor and Nuclear Fuel Development Corporation (PNC), Japan. The models and methods of SIMMER-III are briefly described with emphasis on recent advances in multi-phase multi-component fluid dynamics technologies and their expected implication on a future reliable transition phase analysis. (author)
Di-boson production measurements with the ATLAS detector
Chevalier, Laurent
2015-01-01
This talk covers the results of the measurements of diboson production cross sections in proton- proton interactions at 7 TeV in 2011 and at 8 TeV in 2012, performed by the ATLAS experiment. The cross sections are measured in phase space regions defined by the decay kinematics, the detector acceptance and then extrapolated to the full phase space. Cross sections for VV (V=W, Z, γ) production in the leptonic or semileptonic channels are compared to (N)NLO predictions of the Standard Model. Kinematic spectra are used to place constraints on anomalous triple-gauge-boson couplings. All cross sections are in agreement with the Standard Model predictions. No experimental evidence is found of anomalous triple-gauge-boson couplings. PACS: 14.70.-e Gauge bosons.
Critical Line of the Deconfinement Phase Transitions
Gorenstein, Mark I.
Phase diagram of strongly interacting matter is discussed within the exactly solvable statistical model of the quark-gluon bags. The model predicts two phases of matter: the hadron gas at a low temperature T and baryonic chemical potential μ B , and the quark-gluon gas at a high T and/or μ B . The nature of the phase transition depends on a form of the bag massvolume spectrum (its pre-exponential factor), which is expected to change with the μ B /T ratio. It is therefore likely that the line of the 1 st order transition at a high μ B/T ratio is followed by the line of the 2 nd order phase transition at an intermediate μ B/T, and then by the lines of "higher order transitions" at a low μ B /T. This talk is based on a recent paper (Gorenstein, Gaździcki, and Greiner, 2005).
The MSSM Electroweak Phase Transition on the Lattice
Laine, Mikko
1998-01-01
We study the MSSM finite temperature electroweak phase transition with lattice Monte Carlo simulations, for a large Higgs mass (m_H ~ 95 GeV) and light stop masses (m_tR ~ 150...160 GeV). We employ a 3d effective field theory approach, where the degrees of freedom appearing in the action are the SU(2) and SU(3) gauge fields, the weakly interacting Higgs doublet, and the strongly interacting stop triplet. We determine the phase diagram, the critical temperatures, the scalar field expectation values, the latent heat, the interface tension and the correlation lengths at the phase transition points. Extrapolating the results to the infinite volume and continuum limits, we find that the transition is stronger than indicated by 2-loop perturbation theory, guaranteeing that the MSSM phase transition is strong enough for baryogenesis in this regime. We also study the possibility of a two-stage phase transition, in which the stop field gets an expectation value in an intermediate phase. We find that a two-stage transi...
A phenomenological study on the production of Higgs bosons in the cSMCS model at the LHC
Directory of Open Access Journals (Sweden)
N. Darvishi
2017-10-01
Full Text Available In the present work, we intend to predict the production rates of the Higgs bosons in the simplest extension of the Standard Model (SM by a neutral complex singlet (cSMCS. This model has an additional source of CP violation and provides strong enough first-order electroweak phase transition to generate the baryon asymmetry of universe (BAU. The scalar spectrum of the cSMCS includes three neutral Higgs particles with the lightest one considered to be the 125 GeV Higgs boson found at LHC. The SM-like Higgs boson comes mostly from the SM-like SU(2 doublet, with a small correction from the singlet. To predict the production rates of the Higgs bosons, we use a conventional effective LO QCD framework and the unintegrated parton distribution functions (UPDF of Kimber–Martin–Ryskin (KMR. We first compute the SM Higgs production cross-section and compare the results to the existing theoretical calculations from different frameworks as well as the experimental data from the CMS and ATLAS collaborations. It is shown that our framework is capable of producing sound predictions for these high-energy QCD events in the SM. Afterwards we present our predictions for the Higgs boson production in the cSMCS.
Manzoni, Stefano; The ATLAS collaboration
2018-01-01
The precise measurement of the properties of the Higgs boson is one of the main goal of the physics research at the LHC. The presentation shows the new results achieved by the ATLAS collaboration in the bosonic Higgs decay channels ($H\\rightarrow\\gamma\\gamma$, $H\\rightarrow ZZ^∗$, $H\\rightarrow WW^∗$) using 36 fb$^{−1}$ of proton-proton collision data recorded at $\\sqrt{s}=13$ TeV during the 2015 and 2016. Cross-section measurements for the production of a Higgs boson through gluon-gluon fusion, vector-boson fusion, and in association with a vector boson or a top-quark pair are reported. The signal strength, defined as the ratio of the observed to the expected signal yield, is measured for each of these production processes as well as inclusively. Moreover measurements of simplified template cross sections, designed to quantify the different Higgs boson production processes in specific regions of phase space, are reported. Finally the presentation shows the measurement of the fiducial cross-section of t...
Hadronization during quark-gluon plasma phase transition
International Nuclear Information System (INIS)
Mohanty, A.K.; Kataria, S.K.
1996-01-01
The hadron multiplicity distributions and factorial moments are studied in the framework of Landau theory of phase transitions. The factorial moments show a scaling law with a scaling exponent ν which characterizes the intermittency properties of the hadron phase for T c (or T t ) where T c (or T t ) is the transition temperature for second (or first) order transition. The scaling exponent ν is weakly dependent on the free energy parameters as well as on temperature. It is shown that ν remains practically constant in the hadron phase for which T c or T t whether the transition is second order or first order of second kind where the free energy expansion includes cubic term. This universality in the scaling exponent is also maintained above T c over a wide range of temperature even if the transition is strongly first order of first kind where the free energy expansion has only even order coefficients, except around the critical temperature T t where T t approx-gt T c . Therefore, the scaling exponent ν is rather more universal and only indicates the presence of a possible phase transition. It is further shown that the hadron multiplicity distribution is quite sensitive to the free energy parameters. The study of hadron multiplicity distribution at various resolution or bin size reveals more information about the dynamics of the phase transition. The calculated hadron multiplicity distributions are also compared with the negative binomial distribution, often used to explain the experimental multiplicity distributions. copyright 1996 The American Physical Society
Two kinds of phase transitions in a voting model
Hisakado, M.; Mori, S.
2012-08-01
In this paper, we discuss a voting model with two candidates, C0 and C1. We consider two types of voters—herders and independents. The voting of independents is based on their fundamental values, while the voting of herders is based on the number of previous votes. We can identify two kinds of phase transitions. One is an information cascade transition similar to a phase transition seen in the Ising model. The other is a transition of super and normal diffusions. These phase transitions coexist. We compared our results to the conclusions of experiments and identified the phase transitions in the upper limit of the time t by using the analysis of human behavior obtained from experiments.
Quarks-bags phase transition in quantum chromodynamics
International Nuclear Information System (INIS)
Gorenshtejn, M.I.
1981-01-01
Phase transitions in the quark-gluon plasma are considered at finite temperatures and chemical potentials. A phenomenological account for a complicated structure of the QCD vacuum results in the necessity to use the formalism of isobaric ensembles to describe the system. The phase transition curve separating the regions of the quark-gluon plasma and the hadronic bag phase in the μT plane is calculated [ru
Unconventional transformation of spin Dirac phase across a topological quantum phase transition
Xu, Su-Yang; Neupane, Madhab; Belopolski, Ilya; Liu, Chang; Alidoust, Nasser; Bian, Guang; Jia, Shuang; Landolt, Gabriel; Slomski, Batosz; Dil, J. Hugo; Shibayev, Pavel P.; Basak, Susmita; Chang, Tay-Rong; Jeng, Horng-Tay; Cava, Robert J.; Lin, Hsin; Bansil, Arun; Hasan, M. Zahid
2015-01-01
The topology of a topological material can be encoded in its surface states. These surface states can only be removed by a bulk topological quantum phase transition into a trivial phase. Here we use photoemission spectroscopy to image the formation of protected surface states in a topological insulator as we chemically tune the system through a topological transition. Surprisingly, we discover an exotic spin-momentum locked, gapped surface state in the trivial phase that shares many important properties with the actual topological surface state in anticipation of the change of topology. Using a spin-resolved measurement, we show that apart from a surface bandgap these states develop spin textures similar to the topological surface states well before the transition. Our results offer a general paradigm for understanding how surface states in topological phases arise from a quantum phase transition and are suggestive for the future realization of Weyl arcs, condensed matter supersymmetry and other fascinating phenomena in the vicinity of a quantum criticality. PMID:25882717
Nematic quantum liquid crystals of bosons in frustrated lattices
Zhu, Guanyu; Koch, Jens; Martin, Ivar
2016-04-01
The problem of interacting bosons in frustrated lattices is an intricate one due to the absence of a unique minimum in the single-particle dispersion where macroscopic number of bosons can condense. Here, we consider a family of tight-binding models with macroscopically degenerate lowest energy bands, separated from other bands by a gap. We predict the formation of exotic states that spontaneously break rotational symmetry at relatively low filling. These states belong to three nematic phases: Wigner crystal, supersolid, and superfluid. The Wigner crystal phase is established exactly at low filling. Supersolid and superfluid phases, at larger filling, are obtained by making use of a projection onto the flat band, construction of an appropriate Wannier basis, and subsequent mean-field treatment. The nematic superfluid that we predict is uniform in real space but has an anisotropic momentum distribution, providing a novel scenario for Bose condensation with an additional nematic order. Our findings open up a promising direction of studying microscopic quantum liquid crystalline phases of bosons.
Probing diffractive production of gauge bosons at forward rapidities
Energy Technology Data Exchange (ETDEWEB)
Basso, Eduardo; Rangel, Murilo S. [Universidade Federal do Rio de Janeiro, Instituto de Fisica, Caixa Postal 68528, Rio de Janeiro, RJ (Brazil); Goncalves, Victor P. [Universidade Federal de Pelotas, Instituto de Fisica e Matematica, Pelotas, RS (Brazil)
2016-12-15
Gauge boson production at forward rapidities in single diffractive events at the LHC is investigated considering pp collisions at √(s) = 8 and 13 TeV. The impact of gap survival effects is analysed using two different models for the soft rescattering contributions. We demonstrate that using the forward shower counter Project at LHCb-HERSCHEL, together with the Vertex Locator-VELO, it is possible to discriminate diffractive production of the gauge bosons W and Z from the non-diffractive processes and studies of the Pomeron structure and diffraction phenomenology are feasible. Moreover, we show that the analysis of this process can be useful to constrain the modelling of the gap survival effects. (orig.)
Quantum trajectory phase transitions in the micromaser.
Garrahan, Juan P; Armour, Andrew D; Lesanovsky, Igor
2011-08-01
We study the dynamics of the single-atom maser, or micromaser, by means of the recently introduced method of thermodynamics of quantum jump trajectories. We find that the dynamics of the micromaser displays multiple space-time phase transitions, i.e., phase transitions in ensembles of quantum jump trajectories. This rich dynamical phase structure becomes apparent when trajectories are classified by dynamical observables that quantify dynamical activity, such as the number of atoms that have changed state while traversing the cavity. The space-time transitions can be either first order or continuous, and are controlled not just by standard parameters of the micromaser but also by nonequilibrium "counting" fields. We discuss how the dynamical phase behavior relates to the better known stationary-state properties of the micromaser.
Echoes of the Glass Transition in Athermal Soft Spheres.
Morse, Peter K; Corwin, Eric I
2017-09-15
Recent theoretical advances have led to the creation of a unified phase diagram for the thermal glass and athermal jamming transitions. This diagram makes clear that, while related, the mode-coupling-or dynamic-glass transition is distinct from the jamming transition, occurring at a finite temperature and significantly lower density than the jamming transition. Nonetheless, we demonstrate a prejamming transition in athermal frictionless spheres which occurs at the same density as the mode-coupling transition and is marked by percolating clusters of locally rigid particles. At this density in both the thermal and athermal systems, individual motions of an extensive number of particles become constrained, such that only collective motion is possible. This transition, which is well below jamming, exactly matches the definition of collective behavior at the dynamical transition of glasses. Thus, we reveal that the genesis of rigidity in both thermal and athermal systems is governed by the same underlying topological transition in their shared configuration space.
An absorbing phase transition from a structured active particle phase
Energy Technology Data Exchange (ETDEWEB)
Lopez, Cristobal [Instituto Mediterraneo de Estudios Avanzados IMEDEA (CSIC-UIB), Campus de la Universidad de las Islas Baleares, E-07122 Palma de Mallorca (Spain); Ramos, Francisco [Departamento de Electromagnetismo y Fisica de la Materia and Instituto de Fisica Teorica y Computacional Carlos I, Facultad de Ciencias, Universidad de Granada, 18071 Granada (Spain); Hernandez-GarcIa, Emilio [Instituto Mediterraneo de Estudios Avanzados IMEDEA (CSIC-UIB), Campus de la Universidad de las Islas Baleares, E-07122 Palma de Mallorca (Spain)
2007-02-14
In this work we study the absorbing state phase transition of a recently introduced model for interacting particles with neighbourhood-dependent reproduction rates. The novelty of the transition is that as soon as the active phase is reached by increasing a control parameter a periodically arranged structure of particle clusters appears. A numerical study in one and two dimensions shows that the system falls into the directed percolation universality class.
International Nuclear Information System (INIS)
Zhang Bin; Liang Yongcheng; Sun Huiyu
2007-01-01
Nanographite sheets under high compressive stresses at ambient temperature have been investigated through molecular dynamics simulations using the Tersoff-Brenner potential. Nanographite undergoes a soft to hard phase transition at a certain compressive stress, about 15 GPa. With increasing compressions, the bonding structures of nanographite are changed, interlayer sp 3 -bonds are formed, and nanographite transforms into a superhard carbon phase (SCP). Further compressions lead to the instabilities of the SCP. Although the detailed lattice structure of the SCP remains elusive, its compressive strength can approach 150 GPa, comparable to that of diamond. The maximum failure stresses of nanographite sheets are sensitive to the inter-and intra-layer interstices. Our results may explain paradoxical experimental results in the available literature
Higher-dimensional bosonization and its application to Fermi liquids
Energy Technology Data Exchange (ETDEWEB)
Meier, Hendrik
2012-06-28
The bosonization scheme presented in this thesis allows to map models of interacting fermions onto equivalent models describing collective bosonic excitations. For simple systems that do not require plenty computational power and optimized algorithms, the positivity of the weight function in the bosonic frame has been confirmed - in particular also for those configurations in which the fermionic representation shows the minus-sign problem. The numerical tests are absolutely elementary and based on the simplest possible regularization scheme. The second part of this thesis presented an analytical study about the non-analytic corrections to thermodynamic quantities in a two-dimensional Fermi liquid. The perturbation theory developed for the exact formulation is by no means more convenient than the well-established fermionic diagram technique. The effective low-energy theory for studying the anomalous contributions to the Fermi liquid was derived focussing on the relevant soft modes of the interaction only. The final effective model took the form of a field theory for a bosonic superfield Ψ interacting in quadratic, cubic, and quartic terms in the action. This field theory turned out nontrivial and was shown to lead to logarithmic divergencies in both spin and charge channels. By means of a combined scheme of ladder diagram summations and renormalization group equations, the logarithmic terms were summed up in the first-loop order, thus yielding the renormalized effective coupling constants of the theory at low temperatures. The fully renormalized action then allowed to conveniently compute the low-temperature limit behavior of the non-analytic corrections to the Fermi-liquid thermodynamic response functions such as the low temperature non-analytic correction δc to the specific heat. The explicit formula for δc is the sum of two contributions - one due to the spin singlet and one due to the spin triplet superconducting excitations. Depending on the values of the
Liquid-liquid phase transition in Stillinger-Weber silicon
International Nuclear Information System (INIS)
Beaucage, Philippe; Mousseau, Normand
2005-01-01
It was recently demonstrated that Stillinger-Weber silicon undergoes a liquid-liquid first-order phase transition deep into the supercooled region (Sastry and Angell 2003 Nat. Mater. 2 739). Here we study the effects of perturbations on this phase transition. We show that the order of the liquid-liquid transition changes with negative pressure. We also find that the liquid-liquid transition disappears when the three-body term of the potential is strengthened by as little as 5%. This implies that the details of the potential could affect strongly the nature and even the existence of the liquid-liquid phase
Acoustic levitation of liquid drops: Dynamics, manipulation and phase transitions.
Zang, Duyang; Yu, Yinkai; Chen, Zhen; Li, Xiaoguang; Wu, Hongjing; Geng, Xingguo
2017-05-01
The technique of acoustic levitation normally produces a standing wave and the potential well of the sound field can be used to trap small objects. Since no solid surface is involved it has been widely applied for the study of fluid physics, nucleation, bio/chemical processes, and various forms of soft matter. In this article, we survey the works on drop dynamics in acoustic levitation, focus on how the dynamic behavior is related to the rheological properties and discuss the possibility to develop a novel rheometer based on this technique. We review the methods and applications of acoustic levitation for the manipulation of both liquid and solid samples and emphasize the important progress made in the study of phase transitions and bio-chemical analysis. We also highlight the possible open areas for future research. Copyright © 2017 Elsevier B.V. All rights reserved.
Gauge boson production at colliders – Predictions for precision studies
Indian Academy of Sciences (India)
2012-10-03
Oct 3, 2012 ... Next-to-leading order; quantum chromodynamics; gauge bosons. PACS Nos 12.38.−t; 12.15.−y. 1. .... to-leading logarithms (NNLL), transverse momentum resummation [11] and soft gluon resummation have been ..... From the figure it is clear that if only the three hardest jets are included in the definition of.
Indian Academy of Sciences (India)
The ferroelectric phase transition is diffuse in nature and broadening of the peak increases with La content. Keywords. PLZT ... Marssi et al (1998) concluded the PLZTs x/65/35 as a model. ∗ ... by analysing field cooled (FC) and zero field cooled (ZFC) dielectric ... material are fitted with universal dielectric behaviour within.
Phase-transition-like behaviour of quantum games
International Nuclear Information System (INIS)
Du Jiangfeng; Li Hui; Xu Xiaodong; Zhou Xianyi; Han Rongdian
2003-01-01
The discontinuous dependence of the properties of a quantum game on its entanglement has been shown to be very much like phase transitions viewed in the entanglement-payoff diagram (J Du et al 2002 Phys. Rev. Lett. 88 137902). In this paper we investigate such phase-transition-like behaviour of quantum games, by suggesting a method which would help to illuminate the origin of such a kind of behaviour. For the particular case of the generalized Prisoners' Dilemma, we find that, for different settings of the numerical values in the payoff table, even though the classical game behaves the same, the quantum game exhibits different and interesting phase-transition-like behaviour
Phase-transition-like behaviour of quantum games
Du Jiang Feng; Xu Xiao Dong; Zhou Xian Yi; Han Rong Dian
2003-01-01
The discontinuous dependence of the properties of a quantum game on its entanglement has been shown to be very much like phase transitions viewed in the entanglement-payoff diagram (J Du et al 2002 Phys. Rev. Lett. 88 137902). In this paper we investigate such phase-transition-like behaviour of quantum games, by suggesting a method which would help to illuminate the origin of such a kind of behaviour. For the particular case of the generalized Prisoners' Dilemma, we find that, for different settings of the numerical values in the payoff table, even though the classical game behaves the same, the quantum game exhibits different and interesting phase-transition-like behaviour.
Sphericity in the interacting boson model
International Nuclear Information System (INIS)
Ogata, H.
1977-01-01
The interacting boson model (IBM) of Arima and Iachello is examined. The transition between the rotational and vibrational modes of even-even nuclei is presented as a function of a sphericity parameter, which is determined primarily from yrast band spectra. The backbending feature is reasonably reproduced. (author)
Observation of the Photon-Blockade Breakdown Phase Transition
Directory of Open Access Journals (Sweden)
J. M. Fink
2017-01-01
Full Text Available Nonequilibrium phase transitions exist in damped-driven open quantum systems when the continuous tuning of an external parameter leads to a transition between two robust steady states. In second-order transitions this change is abrupt at a critical point, whereas in first-order transitions the two phases can coexist in a critical hysteresis domain. Here, we report the observation of a first-order dissipative quantum phase transition in a driven circuit quantum electrodynamics system. It takes place when the photon blockade of the driven cavity-atom system is broken by increasing the drive power. The observed experimental signature is a bimodal phase space distribution with varying weights controlled by the drive strength. Our measurements show an improved stabilization of the classical attractors up to the millisecond range when the size of the quantum system is increased from one to three artificial atoms. The formation of such robust pointer states could be used for new quantum measurement schemes or to investigate multiphoton phases of finite-size, nonlinear, open quantum systems.
Electron scattering in the interacting boson model
Dieperink, AEL; Iachello, F; Rinat, A; Creswell, C
1978-01-01
It is suggested that the interacting boson model be used in the analysis of electron scattering data. Qualitative features of the expected behavior of the inelastic excitation of some 2 ÷ states inthe transitional Sm-Nd region are discussed
Comment on ''Spectroscopy of samarium isotopes in the sdg interacting boson model''
International Nuclear Information System (INIS)
Kuyucak, S.; Lac, V.
1993-01-01
We point out that the data used in the sdg boson model calculations by Devi and Kota [Phys. Rev. C 45, 2238 (1992)] can be equally well described by the much simpler sd boson model. We present additional data for the Sm isotopes which cannot be explained in the sd model and hence may justify such an extension to the sdg bosons. We also comment on the form of the Hamiltonian and the transition operators used in this paper
Phase-Contrast Hounsfield Units of Fixated and Non-Fixated Soft-Tissue Samples
Willner, Marian; Fior, Gabriel; Marschner, Mathias; Birnbacher, Lorenz; Schock, Jonathan; Braun, Christian; Fingerle, Alexander A.; Noël, Peter B.; Rummeny, Ernst J.; Pfeiffer, Franz; Herzen, Julia
2015-01-01
X-ray phase-contrast imaging is a novel technology that achieves high soft-tissue contrast. Although its clinical impact is still under investigation, the technique may potentially improve clinical diagnostics. In conventional attenuation-based X-ray computed tomography, radiological diagnostics are quantified by Hounsfield units. Corresponding Hounsfield units for phase-contrast imaging have been recently introduced, enabling a setup-independent comparison and standardized interpretation of imaging results. Thus far, the experimental values of few tissue types have been reported; these values have been determined from fixated tissue samples. This study presents phase-contrast Hounsfield units for various types of non-fixated human soft tissues. A large variety of tissue specimens ranging from adipose, muscle and connective tissues to liver, kidney and pancreas tissues were imaged by a grating interferometer with a rotating-anode X-ray tube and a photon-counting detector. Furthermore, we investigated the effects of formalin fixation on the quantitative phase-contrast imaging results. PMID:26322638
Nonequilibrium thermodynamic fluctuations and phase transition in black holes
International Nuclear Information System (INIS)
Su, R.; Cai, R.; Yu, P.K.N.
1994-01-01
Landau nonequilibrium fluctuation and phase transition theory is applied to the discussion of the phase transition of black holes. Some second moments of relevant thermodynamical quantities for Kerr-Newman black holes are estimated. A theorem governing the divergence of some second moments and the occurrence of the phase transition in black holes is given
Phase transitions and critical behaviour for charged black holes
International Nuclear Information System (INIS)
Carlip, S; Vaidya, S
2003-01-01
We investigate the thermodynamics of a four-dimensional charged black hole in a finite cavity in asymptotically flat and asymptotically de Sitter spaces. In each case, we find a Hawking-Page-like phase transition between a black hole and a thermal gas very much like the known transition in asymptotically anti-de Sitter space. For a 'supercooled' black hole - a thermodynamically unstable black hole below the critical temperature for the Hawking-Page phase transition - the phase diagram has a line of first-order phase transitions that terminates in a second-order point. For the asymptotically flat case, we calculate the critical exponents at the second-order phase transition and find that they exactly match the known results for a charged black hole in anti-de Sitter space. We find strong evidence for similar phase transitions for the de Sitter black hole as well. Thus many of the thermodynamic features of charged anti-de Sitter black holes do not really depend on asymptotically anti-de Sitter boundary conditions; the thermodynamics of charged black holes is surprisingly universal
A grain boundary phase transition in Si–Au
International Nuclear Information System (INIS)
Ma, Shuailei; Meshinchi Asl, Kaveh; Tansarawiput, Chookiat; Cantwell, Patrick R.; Qi, Minghao; Harmer, Martin P.; Luo, Jian
2012-01-01
A grain boundary transition from a bilayer to an intrinsic (nominally clean) boundary is observed in Si–Au. An atomically abrupt transition between the two complexions (grain boundary stabilized phases) implies the occurrence of a first-order interfacial phase transition associated with a discontinuity in the interfacial excess. This observation supports a grain-boundary complexion theory with broad applications. This transition is atypical in that the monolayer complexion is absent. A model is proposed to explain the bilayer stabilization and the origin of this complexion transition.
Lightest Higgs boson mass in split supersymmetry with the seesaw mechanism
International Nuclear Information System (INIS)
Cao Junjie; Yang Jinmin
2005-01-01
In the minimal supersymmetric standard model extended by including right-handed neutrinos with seesaw mechanism, the neutrino Yukaka couplings can be as large as the top-quark Yukawa couplings and thus the neutrino/sneutrino may cause sizable effects in Higgs boson self-energy loops. Our explicit one-loop calculations show that the neutrino/sneutrino effects may have an opposite sign to top/stop effects and thus lighten the lightest Higgs boson. If the soft-breaking mass of the right-handed neutrino is very large (at the order of Majorana mass scale), such as in the split-supersymmetry (SUSY) scenario, the effects can lower the lightest Higgs boson mass by a few tens of GeV. So the Higgs mass bound of about 150 GeV in split-SUSY may be lowered significantly if right-handed neutrinos come into play with seesaw mechanism
Phase Transitions in Geomorphology
Ortiz, C. P.; Jerolmack, D. J.
2015-12-01
Landscapes are patterns in a dynamic steady-state, due to competing processes that smooth or sharpen features over large distances and times. Geomorphic transport laws have been developed to model the mass-flux due to different processes, but are unreasonably effective at recovering the scaling relations of landscape features. Using a continuum approximation to compare experimental landscapes and the observed landscapes of the earth, one finds they share similar morphodynamics despite a breakdown of classical dynamical similarity between the two. We propose the origin of this effectiveness is a different kind of dynamic similarity in the statistics of initiation and cessation of motion of groups of grains, which is common to disordered systems of grains under external driving. We will show how the existing data of sediment transport points to common signatures with dynamical phase transitions between "mobile" and "immobile" phases in other disordered systems, particularly granular materials, colloids, and foams. Viewing landscape evolution from the lens of non-equilibrium statistical physics of disordered systems leads to predictions that the transition of bulk measurements such as particle flux is continuous from one phase to another, that the collective nature of the particle dynamics leads to very slow aging of bulk properties, and that the dynamics are history-dependent. Recent results from sediment transport experiments support these predictions, suggesting that existing geomorphic transport laws may need to be replaced by a new generation of stochastic models with ingredients based on the physics of disordered phase transitions. We discuss possible strategies for extracting the necessary information to develop these models from measurements of geomorphic transport noise by connecting particle-scale collective dynamics and space-time fluctuations over landscape features.
Multiple multi-orbit fermionic and bosonic pairing and rotational SU(3) algebras
International Nuclear Information System (INIS)
Kota, V.K.B.
2017-01-01
In nuclei with valence nucleons that are identical nucleons and occupy r number of j-orbits, there will be 2 r-1 number of multiple pairing (quasi-spin) SU(2) algebras with the generalized pair creation operator S + being a sum of single-j pair creation operators with arbitrary phases. Also, for each set of phases there will be a corresponding Sp(2Ω) algebra in U(2Ω) ⊃ Sp(2Ω); Ω = ∑ (2j+1)/2. Using this correspondence, derived is the condition for a general one-body operator of angular momentum rank k to be a quasi-spin scalar or a vector vis-a-vis the phases in S + . These will give special seniority selection rules for electromagnetic transitions. We found that the phase choice advocated by Arvieu and Moszkowski gives pairing Hamiltonians having maximum correlation with well known effective interactions. All the results derived for identical fermion systems are shown to extend to identical boson systems such as sd, sp, sdg and sdpf interacting boson models (IBM's) with SU(2) → SU(1,1) and Sp(2/Omega) → SO(2Ω). Going beyond pairing, for a given set of oscillator orbits, there are multiple rotational SU(3) algebras both in shell model and IBM's. Different SU(3) algebras in IBM's are shown, using sdg IBM as an example, to give different geometric shapes.
Electron scattering in the interacting boson model
International Nuclear Information System (INIS)
Dieperink, A.E.L.; Iachello, F.; Creswell, C.
1978-01-01
It is suggested that the interacting boson model be used in the analysis of electron scattering data. Qualitative features of the expected behavior of the inelastic excitation of some 2 + states in the transitional Sm-Nd region are discussed. (Auth.)
International Nuclear Information System (INIS)
Blaschke, D.; Ebert, D.; Klimenko, K.G.; Volkov, M.K.; Yudichev, V.L.
2004-01-01
We consider an extended Nambu-Jona-Lasinio model including both (qq-bar) and (qq) interactions with two light-quark flavors in the presence of a single (quark density) chemical potential. In the color superconducting phase of the quark matter the color SU c (3) symmetry is spontaneously broken down to SU c (2). If the usual counting of Goldstone bosons would apply, five Nambu-Goldstone (NG) bosons corresponding to the five broken color generators should appear in the mass spectrum. Unlike that expectation, we find only three gapless diquark excitations of quark matter. One of them is an SU c (2) singlet; the remaining two form an SU c (2) (anti)doublet and have a quadratic dispersion law in the small momentum limit. These results are in agreement with the Nielsen-Chadha theorem, according to which NG bosons in Lorentz-noninvariant systems, having a quadratic dispersion law, must be counted differently. The origin of the abnormal number of NG bosons is shown to be related to a nonvanishing expectation value of the color charge operator Q 8 reflecting the lack of color neutrality of the ground state. Finally, by requiring color neutrality, two massive diquarks are argued to become massless, resulting in a normal number of five NG bosons with the usual linear dispersion laws
The comparison of bosonic and fermionic descriptions of collective nuclear structure
International Nuclear Information System (INIS)
Baktybaev, K.
2004-01-01
Full text: Bosonic and fermionic descriptions for the nuclear many body system are complementary. The archetypical bosonic algebra is the original interacting boson model [1]. Without distinguishing between proton and neutron bosons, it gave rise to successful phenomenology for medium and heavy nuclei, and is built from the concept of dynamical symmetry whose genesis is a group chain. The fermionic algebra on the other hand, such as the fermion dynamical symmetry model (FDSM) [2], is necessarily more complex because it originates from the shell structure and uses protons and neutrons as building blocks. We have presented two complementary pictures of bosons and fermions to describe the normal and the exotic states. We find that the bosonic concepts of symmetry and mixed- symmetry can subtly be interpreted within the fermion picture as well. However, there is one important dichotomy. In the fermion description, the n-p quadrupole interaction is responsible for splitting these two type of states and produces strong M1 transitions. This phenomenon is in close analogy to the L-S splitting of orbital and spin spaces. The examples given in the paper show that many 2 + normal and exotic states are in fact 'partners' for n-p quadrupole coupling and there fore must split in its presence. We would like to emphasize that the proper placement of the positions of the exotic states and the prediction of their respective transitions must be another stringent constraint on the effective interactions of the Hamiltonian
Higgs boson events and background lep. A Monte Carlo study
International Nuclear Information System (INIS)
Ekspong, G.; Hultqvist, K.
1982-06-01
Higgs boson production at LEP using e+ e- to Z 0 to H 0 + e+ e- has been studied by Monte Carlo generation of events with realistic errors of measurement added. The results show the recoil mass (Higgs boson mass) resolution to be reasonably good for boson masses bigger than 5 Ge V. The events are found to populate a phase space region free of physical background for all boson masses below about 35 GeV. For masses above 40 GeV the Higgs boson signal merges with the physical background produced by semileptonic decays of heavy flavour quarks while diminishing in strength to low levels. The geometrical acceptance of a detector like DELPHI is about 80 per cent for Higgs boson events. (Author)
Phase transitions in solids under high pressure
Blank, Vladimir Davydovich
2013-01-01
Phase equilibria and kinetics of phase transformations under high pressureEquipment and methods for the study of phase transformations in solids at high pressuresPhase transformations of carbon and boron nitride at high pressure and deformation under pressurePhase transitions in Si and Ge at high pressure and deformation under pressurePolymorphic α-ω transformation in titanium, zirconium and zirconium-titanium alloys Phase transformations in iron and its alloys at high pressure Phase transformations in gallium and ceriumOn the possible polymorphic transformations in transition metals under pressurePressure-induced polymorphic transformations in АIBVII compoundsPhase transformations in AIIBVI and AIIIBV semiconductor compoundsEffect of pressure on the kinetics of phase transformations in iron alloysTransformations during deformation at high pressure Effects due to phase transformations at high pressureKinetics and hysteresis in high-temperature polymorphic transformations under pressureHysteresis and kineti...
Late time phase transition as dark energy
Indian Academy of Sciences (India)
Abstract. We show that the dark energy field can naturally be described by the scalar condensates of a non-abelian gauge group. This gauge group is unified with the standard model gauge groups and it has a late time phase transition. The small phase transition explains why the positive acceleration of the universe is ...
Phase separation in the nonequilibrium Verwey transition in magnetite
Randi, F.; Vergara, I.; Novelli, F.; Esposito, M.; Dell'Angela, M.; Brabers, V. A. M.; Metcalf, P.; Kukreja, R.; Dürr, H. A.; Fausti, D.; Grüninger, M.; Parmigiani, F.
2016-02-01
We present equilibrium and out-of-equilibrium studies of the Verwey transition in magnetite. In the equilibrium optical conductivity, we find a steplike change at the phase transition for photon energies below about 2 eV. The possibility of triggering a nonequilibrium transient metallic state in insulating magnetite by photo excitation was recently demonstrated by an x-ray study. Here we report a full characterization of the optical properties in the visible frequency range across the nonequilibrium phase transition. Our analysis of the spectral features is based on a detailed description of the equilibrium properties. The out-of-equilibrium optical data bear the initial electronic response associated to localized photoexcitation, the occurrence of phase separation, and the transition to a transient metallic phase for excitation density larger than a critical value. This allows us to identify the electronic nature of the transient state, to unveil the phase transition dynamics, and to study the consequences of phase separation on the reflectivity, suggesting a spectroscopic feature that may be generally linked to out-of-equilibrium phase separation.
Liquid-liquid phase transition and glass transition in a monoatomic model system.
Xu, Limei; Buldyrev, Sergey V; Giovambattista, Nicolas; Stanley, H Eugene
2010-01-01
We review our recent study on the polyamorphism of the liquid and glass states in a monatomic system, a two-scale spherical-symmetric Jagla model with both attractive and repulsive interactions. This potential with a parametrization for which crystallization can be avoided and both the glass transition and the liquid-liquid phase transition are clearly separated, displays water-like anomalies as well as polyamorphism in both liquid and glassy states, providing a unique opportunity to study the interplay between the liquid-liquid phase transition and the glass transition. Our study on a simple model may be useful in understanding recent studies of polyamorphism in metallic glasses.
Liquid-Liquid Phase Transition and Glass Transition in a Monoatomic Model System
Directory of Open Access Journals (Sweden)
Nicolas Giovambattista
2010-12-01
Full Text Available We review our recent study on the polyamorphism of the liquid and glass states in a monatomic system, a two-scale spherical-symmetric Jagla model with both attractive and repulsive interactions. This potential with a parametrization for which crystallization can be avoided and both the glass transition and the liquid-liquid phase transition are clearly separated, displays water-like anomalies as well as polyamorphism in both liquid and glassy states, providing a unique opportunity to study the interplay between the liquid-liquid phase transition and the glass transition. Our study on a simple model may be useful in understanding recent studies of polyamorphism in metallic glasses.
Surface phase transitions in cu-based solid solutions
Zhevnenko, S. N.; Chernyshikhin, S. V.
2017-11-01
We have measured surface energy in two-component Cu-based systems in H2 + Ar gas atmosphere. The experiments on solid Cu [Ag] and Cu [Co] solutions show presence of phase transitions on the surfaces. Isotherms of the surface energy have singularities (the minimum in the case of copper solid solutions with silver and the maximum in the case of solid solutions with cobalt). In both cases, the surface phase transitions cause deficiency of surface miscibility: formation of a monolayer (multilayer) (Cu-Ag) or of nanoscale particles (Cu-Co). At the same time, according to the volume phase diagrams, the concentration and temperature of the surface phase transitions correspond to the solid solution within the volume. The method permits determining the rate of diffusional creep in addition to the surface energy. The temperature and concentration dependence of the solid solutions' viscosity coefficient supports the fact of the surface phase transitions and provides insights into the diffusion properties of the transforming surfaces.
The infinite limit as an eliminable approximation for phase transitions
Ardourel, Vincent
2018-05-01
It is generally claimed that infinite idealizations are required for explaining phase transitions within statistical mechanics (e.g. Batterman 2011). Nevertheless, Menon and Callender (2013) have outlined theoretical approaches that describe phase transitions without using the infinite limit. This paper closely investigates one of these approaches, which consists of studying the complex zeros of the partition function (Borrmann et al., 2000). Based on this theory, I argue for the plausibility for eliminating the infinite limit for studying phase transitions. I offer a new account for phase transitions in finite systems, and I argue for the use of the infinite limit as an approximation for studying phase transitions in large systems.
Phase transitions in field theory
International Nuclear Information System (INIS)
Carvalho, C.A.A. de; Bollini, C.G.; Giambiagi, J.J.
1984-01-01
By means of an example for which the effective potential is explicitly calculable (up to the one loop approximation), it is discussed how a phase transition takes place as the temperature is increased and pass from spontaneously broken symmetry to a phase in which the symmetry is restored. (Author) [pt
Sensing of phase transition in medium with terahertz pulsed spectroscopy
International Nuclear Information System (INIS)
Zaytsev, Kirill I; Fokina, Irina N; Fedorov, Aleksey K; Yurchenko, Stanislav O
2014-01-01
Phase state identification and phase transition registration in condensed matter are significant applications of terahertz spectroscopy. A set of fundamental and applied problems are associated with the phase state problem. Our report is devoted to the experimental analysis of the spectral characteristics of water and water solution during the phase transition from the solid state to the liquid state via the method of terahertz pulsed spectroscopy. In this work transformation of the sample spectral characteristics during the phase transition were observed and discussed. Possible application of terahertz pulsed spectroscopy as an effective instrument for phase transition sensing was considered
Phase transition to QGP matter : confined vs deconfined matter
Maire, Antonin
2015-01-01
Simplified phase diagram of the nuclear phase transition, from the regular hadronic matter to the QGP phase. The sketch is meant to describe the transition foreseen along the temperature axis, at low baryochemical potential, µB.
Iron Damage and Spalling Behavior below and above Shock Induced α ε Phase Transition
International Nuclear Information System (INIS)
Voltz, Christophe; Buy, Francois; Roy, Gilles
2006-01-01
The study of dynamic damage and fracture of iron has been undertaken below and above phase transition by series of time resolved experiments using both light gas launcher and powder gun. Shock wave tests were conducted by symmetrical impacts of high purity iron. To reveal the material behavior we have done shock experiments where the target is covered with a window in order to limit release amplitude and to avoid specimen fragmentation. Metallurgical analysis of soft recovered samples yields information about damage and fracture processes related to thermo-mechanical loading paths. Tests conducted without window allow studying effects of both phase change and release transition. Optical and SEM characterizations lead us to observe several modes of damage: brittle, ductile diffuse with void growth and heavily localized smooth one. These figures are related with: rarefaction shock waves or interfaces between transformed and not transformed iron. Simulations are performed with the 1D to compare experimental data with numerical results. We explain post-mortem observations by the complex shock wave structure interactions: P1 and P2 shock fronts associated with some corresponding shock release during unloading stages
Aql X-1 transition towards the soft (banana) state accompanied by radio/NIR detection
Sivakoff, G. R.; Miller-Jones, J.; Fox, O.; Linares, M.; Altamirano, D.; Russell, D.
2009-11-01
The currently active neutron star transient and atoll source Aql X-1 (Linares et al., ATEL #2288) has begun the transition from the hard (extreme island) state to the soft (banana) state (Rodriguez et al. ATEL #2299). This transition likely began around 2009 Nov 15 (MJD = 55150). The latest RXTE PCA observation (2009 Nov 17, MJD=55152.17+/-0.02, 2-60 keV fractional rms variability amplitude of ~11% for 0.1-10 Hz) indicates that the source is in the intermediate (island) state.
Exceptional Points and Dynamical Phase Transitions
Directory of Open Access Journals (Sweden)
I. Rotter
2010-01-01
Full Text Available In the framework of non-Hermitian quantum physics, the relation between exceptional points,dynamical phase transitions and the counter intuitive behavior of quantum systems at high level density is considered. The theoretical results obtained for open quantum systems and proven experimentally some years ago on a microwave cavity, may explain environmentally induce deffects (including dynamical phase transitions, which have been observed in various experimental studies. They also agree(qualitatively with the experimental results reported recently in PT symmetric optical lattices.
Search for Higgs Bosons in $e^{+} e^{-}$ Collisions at 183 GeV
Abbiendi, G.; Alexander, G.; Allison, John; Altekamp, N.; Anderson, K.J.; Anderson, S.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Ball, A.H.; Barberio, E.; Barlow, Roger J.; Bartoldus, R.; Batley, J.R.; Baumann, S.; Bechtluft, J.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Betts, S.; Biebel, O.; Biguzzi, A.; Bird, S.D.; Blobel, V.; Bloodworth, I.J.; Bock, P.; Bohme, J.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Chrisman, D.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Conboy, J.E.; Cooke, O.C.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Davis, R.; De Jong, S.; de Roeck, A.; Dervan, P.; Desch, K.; Dienes, B.; Dixit, M.S.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Eatough, D.; Estabrooks, P.G.; Etzion, E.; Fabbri, F.; Fanti, M.; Faust, A.A.; Fiedler, F.; Fierro, M.; Fleck, I.; Folman, R.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gascon, J.; Gascon-Shotkin, S.M.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Gibson, V.; Gibson, W.R.; Gingrich, D.M.; Glenzinski, D.; Goldberg, J.; Gorn, W.; Grandi, C.; Graham, K.; Gross, E.; Grunhaus, J.; Gruwe, M.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Harel, A.; Hargrove, C.K.; Hartmann, C.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herndon, M.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hobson, P.R.; Hoch, M.; Hocker, James Andrew; Hoffman, Kara Dion; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Imrie, D.C.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jimack, M.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Kayal, P.I.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Koetke, D.S.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kyberd, P.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lauber, J.; Lautenschlager, S.R.; Lawson, I.; Layter, J.G.; Lazic, D.; Lee, A.M.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Ludwig, J.; Lui, D.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Markopoulos, C.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menke, S.; Merritt, F.S.; Mes, H.; Meyer, J.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mir, R.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nellen, B.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Oreglia, M.J.; Orito, S.; Palinkas, J.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Perez-Ochoa, R.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poffenberger, P.; Polok, J.; Przybycien, M.; Rembser, C.; Rick, H.; Robertson, S.; Robins, S.A.; Rodning, N.; Roney, J.M.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sang, W.M.; Sarkisian, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharf, F.; Scharff-Hansen, P.; Schieck, J.; Schmitt, B.; Schmitt, S.; Schoning, A.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Sittler, A.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Sproston, M.; Stahl, A.; Stephens, K.; Steuerer, J.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Talbot, S.D.; Tanaka, S.; Taras, P.; Tarem, S.; Teuscher, R.; Thiergen, M.; Thomas, J.; Thomson, M.A.; von Torne, E.; Torrence, E.; Towers, S.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turcot, A.S.; Turner-Watson, M.F.; Ueda, I.; Van Kooten, Rick J.; Vannerem, P.; Verzocchi, M.; Voss, H.; Wackerle, F.; Wagner, A.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wermes, N.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Yekutieli, G.; Zacek, V.; Zer-Zion, D.
1999-01-01
The data collected by the OPAL experiment at sqrts=183 GeV were used to search for Higgs bosons which are predicted by the Standard Model and various extensions, such as general models with two Higgs field doublets and the Minimal Supersymmetric Standard Model (MSSM). The data correspond to an integrated luminosity of approximately 54pb-1. None of the searches for neutral and charged Higgs bosons have revealed an excess of events beyond the expected background. This negative outcome, in combination with similar results from searches at lower energies, leads to new limits for the Higgs boson masses and other model parameters. In particular, the 95% confidence level lower limit for the mass of the Standard Model Higgs boson is 88.3 GeV. Charged Higgs bosons can be excluded for masses up to 59.5 GeV. In the MSSM, mh > 70.5 GeV and mA > 72.0 GeV are obtained for tan{beta}>1, no and maximal scalar top mixing and soft SUSY-breaking masses of 1 TeV. The range 0.8 < tanb < 1.9 is excluded for minimal scalar top...
Universal Four-Boson System: Dimer-Atom-Atom Efimov Effect and Recombination Reactions
International Nuclear Information System (INIS)
Deltuva, A.
2013-01-01
Recent theoretical developments in the four-boson system with resonant interactions are described. Momentum-space scattering equations for the four-particle transition operators are used. The properties of unstable tetramers with approximate dimer-atom-atom structure are determined. In addition, the three- and four-cluster recombination processes in the four-boson system are studied. (author)
Two kinds of Phase transitions in a Voting model
Hisakado, Masato; Mori, Shintaro
2012-01-01
In this paper, we discuss a voting model with two candidates, C_0 and C_1. We consider two types of voters--herders and independents. The voting of independents is based on their fundamental values; on the other hand, the voting of herders is based on the number of previous votes. We can identify two kinds of phase transitions. One is an information cascade transition similar to a phase transition seen in Ising model. The other is a transition of super and normal diffusions. These phase trans...
Friction forces on phase transition fronts
International Nuclear Information System (INIS)
Mégevand, Ariel
2013-01-01
In cosmological first-order phase transitions, the microscopic interaction of the phase transition fronts with non-equilibrium plasma particles manifests itself macroscopically as friction forces. In general, it is a nontrivial problem to compute these forces, and only two limits have been studied, namely, that of very slow walls and, more recently, ultra-relativistic walls which run away. In this paper we consider ultra-relativistic velocities and show that stationary solutions still exist when the parameters allow the existence of runaway walls. Hence, we discuss the necessary and sufficient conditions for the fronts to actually run away. We also propose a phenomenological model for the friction, which interpolates between the non-relativistic and ultra-relativistic values. Thus, the friction depends on two friction coefficients which can be calculated for specific models. We then study the velocity of phase transition fronts as a function of the friction parameters, the thermodynamic parameters, and the amount of supercooling
Mott transition in the Hubbard model
International Nuclear Information System (INIS)
Shastry, B.S.
1992-01-01
In this article, the author discuss W. Kohn's criterion for a metal insulator transition, within the framework of a one-band Hubbard model. This and related ideas are applied to 1-dimensional Hubbard systems, and some interesting miscellaneous results discussed. The Jordan-Wigner transformation converting the two species of fermions to two species of hardcore bosons is performed in detail, and the extra phases arising from odd-even effects are explicitly derived. Bosons are shown to prefer zero flux (i.e., diamagnetism) and the corresponding happy fluxes: for the fermions identified. A curios result following from the interplay between orbital diamagnetism and spin polarization is highlighted. A spin-statistics like theorem, showing that the anticommutation relations between fermions of opposite spin are crucial to obtain the SU(2) invariance is pointed out
Scaling theory and the classification of phase transitions
International Nuclear Information System (INIS)
Hilfer, R.
1992-01-01
In this paper, the recent classification theory for phase transitions and its relation with the foundations of statistical physics is reviewed. First it is outlined how Ehrenfests classification scheme can be generalized into a general thermodynamic classification theory for phase transitions. The classification theory implies scaling and multiscaling thereby eliminating the need to postulate the scaling hypothesis as a fourth law of thermodynamics. The new classification has also led to the discovery and distinction of nonequilibrium transitions within equilibrium statistical physics. Nonequilibrium phase transitions are distinguished from equilibrium transitions by orders less than unity and by the fact the equilibrium thermodynamics and statistical mechanics become inapplicable at the critical point. The latter fact requires a change in the Gibbs assumption underlying the canonical and grandcanonical ensembles in order to recover the thermodynamic description in the critical limit
International Nuclear Information System (INIS)
Wu, Liang; Hou, Tingjun; Wang, Yi; Zhao, Yanfei; Guo, Zhenyu; Li, Youyong; Lee, Shuit-Tong
2012-01-01
Highlights: ► We study the doping effect on B4, B1 structures and phase transition of ZnO. ► We calculate the phase transition barrier and phase transition path of doped ZnO. ► The transition metal doping decreases the bulk modulus and phase transition pressure. ► The magnetic properties are influenced by the phase transition process. - Abstract: Zinc oxide (ZnO) is a promising material for its wide application in solid-state devices. With the pressure raised from an ambient condition, ZnO transforms from fourfold wurtzite (B4) to sixfold coordinated rocksalt (B1) structure. Doping is an efficient approach to improve the structures and properties of materials. Here we use density-functional theory (DFT) to study doped ZnO and find that the transition pressure from B4 phase to B1 phase of ZnO always decreases with different types of transition metal (V, Cr, Mn, Fe, Co, or Ni) doped, but the phase transition path is not affected by doping. This is consistent with the available experimental results for Mn-doped ZnO and Co-doped ZnO. Doping in ZnO causes the lattice distortion, which leads to the decrease of the bulk modulus and accelerates the phase transition. Mn-doped ZnO shows the strongest magnetic moment due to its half filled d orbital. For V-doped ZnO and Cr-doped ZnO, the magnetism is enhanced by phase transition from B4 to B1. But for Mn-doped ZnO, Fe-doped ZnO, Co-doped ZnO, and Ni-doped ZnO, B1 phase shows weaker magnetic moment than B4 phase. These results can be explained by the amount of charge transferred from the doped atom to O atom. Our results provide a theoretical basis for the doping approach to change the structures and properties of ZnO.
International Nuclear Information System (INIS)
Strinati, G.C.; Pieri, P.
2004-01-01
The linear response to a space- and time-dependent external disturbance of a system of dilute condensed composite bosons at zero temperature, as obtained from the linearized version of the time-dependent Gross-Pitaevskii equation, is shown to result also from the strong-coupling limit of the time-dependent BCS (or broken-symmetry random-phase) approximation for the constituent fermions subject to the same external disturbance. In this way, it is possible to connect excited-state properties of the bosonic and fermionic systems by placing the Gross-Pitaevskii equation in perspective with the corresponding fermionic approximations
A Bayesian Interpretation of First-Order Phase Transitions
Davis, Sergio; Peralta, Joaquín; Navarrete, Yasmín; González, Diego; Gutiérrez, Gonzalo
2016-03-01
In this work we review the formalism used in describing the thermodynamics of first-order phase transitions from the point of view of maximum entropy inference. We present the concepts of transition temperature, latent heat and entropy difference between phases as emergent from the more fundamental concept of internal energy, after a statistical inference analysis. We explicitly demonstrate this point of view by making inferences on a simple game, resulting in the same formalism as in thermodynamical phase transitions. We show that analogous quantities will inevitably arise in any problem of inferring the result of a yes/no question, given two different states of knowledge and information in the form of expectation values. This exposition may help to clarify the role of these thermodynamical quantities in the context of different first-order phase transitions such as the case of magnetic Hamiltonians (e.g. the Potts model).
Bubble nucleation and growth in very strong cosmological phase transitions
Energy Technology Data Exchange (ETDEWEB)
Mégevand, Ariel, E-mail: megevand@mdp.edu.ar; Ramírez, Santiago
2017-06-15
Strongly first-order phase transitions, i.e., those with a large order parameter, are characterized by a considerable supercooling and high velocities of phase transition fronts. A very strong phase transition may have important cosmological consequences due to the departures from equilibrium caused in the plasma. In general, there is a limit to the strength, since the metastability of the old phase may prevent the transition to complete. Near this limit, the bubble nucleation rate achieves a maximum and thus departs from the widely assumed behavior in which it grows exponentially with time. We study the dynamics of this kind of phase transitions. We show that in some cases a gaussian approximation for the nucleation rate is more suitable, and in such a case we solve analytically the evolution of the phase transition. We compare the gaussian and exponential approximations with realistic cases and we determine their ranges of validity. We also discuss the implications for cosmic remnants such as gravitational waves.
Reconstructive structural phase transitions in dense Mg
International Nuclear Information System (INIS)
Yao Yansun; Klug, Dennis D
2012-01-01
The question raised recently about whether the high-pressure phase transitions of Mg follow a hexagonal close-packed (hcp) → body centered cubic (bcc) or hcp → double hexagonal close-packed (dhcp) → bcc sequence at room temperature is examined by the use of first principles density functional methods. Enthalpy calculations show that the bcc structure replaces the hcp structure to become the most stable structure near 48 GPa, whereas the dhcp structure is never the most stable structure in the pressure range of interest. The characterized phase-transition mechanisms indicate that the hcp → dhcp transition is also associated with a higher enthalpy barrier. At room temperature, the structural sequence hcp → bcc is therefore more energetically favorable for Mg. The same conclusion is also reached from the simulations of the phase transitions using metadynamics methods. At room temperature, the metadynamics simulations predict the onset of a hcp → bcc transition at 40 GPa and the transition becomes more prominent upon further compression. At high temperatures, the metadynamics simulations reveal a structural fluctuation among the hcp, dhcp, and bcc structures at 15 GPa. With increasing pressure, the structural evolution at high temperatures becomes more unambiguous and eventually settles to a bcc structure once sufficient pressure is applied. (paper)
A Solvable Model for Nuclear Shape Phase Transitions
International Nuclear Information System (INIS)
Levai, G.; Arias, J. M.
2009-01-01
There has been considerable interest recently in phase transitions that occur between some well-defined nuclear shapes, e.g. the spherical vibrator, the axially deformed rotor and the γ-unstable rotor, which are assigned to the U(5), SU(3) and 0(6) symmetries. These shape phase transitions occur through critical points of the IBM phase diagram and correspond to rapid structural changes. The first transition of this type describes transition form the spherical to the γ-unstable phase and has been associated with an E(5) symmetry. Later further critical point symmetries e.g. X(5) and Y(5) have also been proposed for transitions between other nuclear shape phases. In another application the chain of even Ru isotopes was considered from A 98 to 112 [2]. The parameters were extracted from a fit to the low-lying energy spectrum of each nucleus and were used to plot the corresponding potential. It was found that up to A =102 the potential is essentially an harmonic oscillator, while at A =104 a rather flat potential was seen, in accordance with the expected phase transition and E(5) symmetry there. With increasing A then the minimum got increasingly deeper and moved away from β = 0. We discuss the possibility of generalizing the formalism in two ways: first by including dependence on the 7 variable allowing for the approximate description of nuclei close to the X(5) symmetry, and second, including higher-lying energy levels in the quasi-exactly solvable formalism
Quantum Phase Transition and Entanglement in Topological Quantum Wires.
Cho, Jaeyoon; Kim, Kun Woo
2017-06-05
We investigate the quantum phase transition of the Su-Schrieffer-Heeger (SSH) model by inspecting the two-site entanglements in the ground state. It is shown that the topological phase transition of the SSH model is signified by a nonanalyticity of local entanglement, which becomes discontinuous for finite even system sizes, and that this nonanalyticity has a topological origin. Such a peculiar singularity has a universal nature in one-dimensional topological phase transitions of noninteracting fermions. We make this clearer by pointing out that an analogous quantity in the Kitaev chain exhibiting the identical nonanalyticity is the local electron density. As a byproduct, we show that there exists a different type of phase transition, whereby the pattern of the two-site entanglements undergoes a sudden change. This transition is characterised solely by quantum information theory and does not accompany the closure of the spectral gap. We analyse the scaling behaviours of the entanglement in the vicinities of the transition points.
Active Surfaces and Interfaces of Soft Materials
Wang, Qiming
A variety of intriguing surface patterns have been observed on developing natural systems, ranging from corrugated surface of white blood cells at nanometer scales to wrinkled dog skins at millimeter scales. To mimetically harness functionalities of natural morphologies, artificial transformative skin systems by using soft active materials have been rationally designed to generate versatile patterns for a variety of engineering applications. The study of the mechanics and design of these dynamic surface patterns on soft active materials are both physically interesting and technologically important. This dissertation starts with studying abundant surface patterns in Nature by constructing a unified phase diagram of surface instabilities on soft materials with minimum numbers of physical parameters. Guided by this integrated phase diagram, an electroactive system is designed to investigate a variety of electrically-induced surface instabilities of elastomers, including electro-creasing, electro-cratering, electro-wrinkling and electro-cavitation. Combing experimental, theoretical and computational methods, the initiation, evolution and transition of these instabilities are analyzed. To apply these dynamic surface instabilities to serving engineering and biology, new techniques of Dynamic Electrostatic Lithography and electroactive anti-biofouling are demonstrated.
High-pressure phase transition of alkali metal-transition metal deuteride Li2PdD2
Yao, Yansun; Stavrou, Elissaios; Goncharov, Alexander F.; Majumdar, Arnab; Wang, Hui; Prakapenka, Vitali B.; Epshteyn, Albert; Purdy, Andrew P.
2017-06-01
A combined theoretical and experimental study of lithium palladium deuteride (Li2PdD2) subjected to pressures up to 50 GPa reveals one structural phase transition near 10 GPa, detected by synchrotron powder x-ray diffraction, and metadynamics simulations. The ambient-pressure tetragonal phase of Li2PdD2 transforms into a monoclinic C2/m phase that is distinct from all known structures of alkali metal-transition metal hydrides/deuterides. The structure of the high-pressure phase was characterized using ab initio computational techniques and from refinement of the powder x-ray diffraction data. In the high-pressure phase, the PdD2 complexes lose molecular integrity and are fused to extended [PdD2]∞ chains. The discovered phase transition and new structure are relevant to the possible hydrogen storage application of Li2PdD2 and alkali metal-transition metal hydrides in general.
Phenomenology of cosmic phase transitions
International Nuclear Information System (INIS)
Kaempfer, B.; Lukacs, B.; Paal, G.
1989-11-01
The evolution of the cosmic matter from Planck temperature to the atomic combination temperature is considered from a phenomenological point of view. Particular emphasis is devoted to the sequence of cosmic phase transitions. The inflationary era at the temperature of the order of the grand unification energy scale and the quantum chromodynamic confinement transition are dealt with in detail. (author) 131 refs.; 26 figs
International Nuclear Information System (INIS)
Ekspong, G.
1981-11-01
Among possible production reactions for neutral Higgs bosons it is known that e + e - →Z 0 +H 0 offers advantages of relatively high production cross section and low background from other reactions. With Z 0 decaying to two electrons, which are measured, the existence of a Higgs candidate will be seen as a peak in the missing mass spectrum. It is shown that a sufficiently good mass resolution is obtainable to make a search for Higgs feasible at LEP. In its first phase, the energy of LEP limits the search to Higgs bosons of mass around 10 GeV. (Auth.)
Vâgberg, Daniel; Olsson, Peter; Teitel, S.
2017-05-01
We report on numerical simulations of simple models of athermal, bidisperse, soft-core, massive disks in two dimensions, as a function of packing fraction ϕ , inelasticity of collisions as measured by a parameter Q , and applied uniform shear strain rate γ ˙. Our particles have contact interactions consisting of normally directed elastic repulsion and viscous dissipation, as well as tangentially directed viscous dissipation, but no interparticle Coulombic friction. Mapping the phase diagram in the (ϕ ,Q ) plane for small γ ˙, we find a sharp first-order rheological phase transition from a region with Bagnoldian rheology to a region with Newtonian rheology, and show that the system is always Newtonian at jamming. We consider the rotational motion of particles and demonstrate the crucial importance that the coupling between rotational and translational degrees of freedom has on the phase structure at small Q (strongly inelastic collisions). At small Q , we show that, upon increasing γ ˙, the sharp Bagnoldian-to-Newtonian transition becomes a coexistence region of finite width in the (ϕ ,γ ˙) plane, with coexisting Bagnoldian and Newtonian shear bands. Crossing this coexistence region by increasing γ ˙ at fixed ϕ , we find that discontinuous shear thickening can result if γ ˙ is varied too rapidly for the system to relax to the shear-banded steady state corresponding to the instantaneous value of γ ˙.
Notes on Phase Transition of Nonsingular Black Hole
International Nuclear Information System (INIS)
Ma Meng-Sen; Zhao Ren
2015-01-01
On the belief that a black hole is a thermodynamic system, we study the phase transition of nonsingular black holes. If the black hole entropy takes the form of the Bekenstein—Hawking area law, the black hole mass M is no longer the internal energy of the black hole thermodynamic system. Using the thermodynamic quantities, we calculate the heat capacity, thermodynamic curvature and free energy. It is shown that there will be a larger black hole/smaller black hole phase transition for the nonsingular black hole. At the critical point, the second-order phase transition appears. (paper)
Novel phase transitions in B-site doped manganites
International Nuclear Information System (INIS)
Popovic, Z.V.; Cantarero, A.; Thijssen, W.H.A.; Paunovic, N.; Dohcevic-Mitrovic, Z.; Sapina, F.
2005-01-01
We have examined the infrared reflectivity and the electrical resistivity of La 1- x [Sr(Ba)] x Mn 1- z [Cu(Zn)] z O 3 samples in ferromagnetic metallic and insulator regime. Several phase transitions are observed, the most obvious being the transition from a ferromagnetic metallic to a ferromagnetic insulator phase that is related to the formation of short-range orbitally ordered domains. The temperature T 1 of the phase transition is dependent on doping concentration and for optimally doped samples (∼32% of Mn 4+ ions) we have found T 1 ∼0.93 T C
Baryogenesis via leptonic CP-violating phase transition
Pascoli, Silvia; Turner, Jessica; Zhou, Ye-Ling
2018-05-01
We propose a new mechanism to generate a lepton asymmetry based on the vacuum CP-violating phase transition (CPPT). This approach differs from classical thermal leptogenesis as a specific seesaw model, and its UV completion, need not be specified. The lepton asymmetry is generated via the dynamically realised coupling of the Weinberg operator during the phase transition. This mechanism provides a connection with low-energy neutrino observables.
High-pressure phase transitions - Examples of classical predictability
Celebonovic, Vladan
1992-09-01
The applicability of the Savic and Kasanin (1962-1967) classical theory of dense matter to laboratory experiments requiring estimates of high-pressure phase transitions was examined by determining phase transition pressures for a set of 19 chemical substances (including elements, hydrocarbons, metal oxides, and salts) for which experimental data were available. A comparison between experimental and transition points and those predicted by the Savic-Kasanin theory showed that the theory can be used for estimating values of transition pressures. The results also support conclusions obtained in previous astronomical applications of the Savic-Kasanin theory.
Energy Technology Data Exchange (ETDEWEB)
Heya, Akira, E-mail: heya@eng.u-hyogo.ac.jp [Department of Materials Science and Chemistry, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671–2280 (Japan); Kanda, Kazuhiro [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Toko, Kaoru; Sadoh, Taizoh [Department of Electronics, Kyushu University, 744 Nishi-ku, Motooka, Fukuoka 819–0395 (Japan); Amano, Sho [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Matsuo, Naoto [Department of Materials Science and Chemistry, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671–2280 (Japan); Miyamoto, Shuji [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Miyao, Masanobu [Department of Electronics, Kyushu University, 744 Nishi-ku, Motooka, Fukuoka 819–0395 (Japan); Mochizuki, Takayasu [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan)
2013-05-01
The low-temperature-crystallization effects of soft X-ray irradiation on the structural properties of amorphous Si and amorphous Ge films were investigated. From the differences in crystallization between Si and Ge, it was found that the effects of soft X-ray irradiation on the crystallization strongly depended on the energy band gap and energy level. The crystallization temperatures of the amorphous Si and amorphous Ge films decreased from 953 K to 853 K and 773 K to 663 K, respectively. The decrease in crystallization temperature was also related to atoms transitioning into a quasi-nucleic phase in the films. The ratio of electron excitation and migration effects to thermal effects was controlled using the storage-ring current (photon flux density). Therefore, we believe that low-temperature crystallization can be realized by controlling atomic migration through electron excitation. - Highlights: • This work investigates the crystallization mechanism for soft X-ray irradiation. • The soft X-ray crystallization depended on the energy band gap and energy level. • The decrease in the crystallization temperature for Si and Ge films was 100 K. • This decrement was related to atoms transitioning into a quasi-nucleic phase.
Gauge theory of glass transition
International Nuclear Information System (INIS)
Vasin, Mikhail
2011-01-01
A new analytical approach for the description of the glass transition in a frustrated system is suggested. The theory is based on the non-equilibrium dynamics technique, and takes into account the interaction of the local order field with the massive gauge field, which describes frustration-induced plastic deformation. The glass transition is regarded as a phase transition interrupted because of the premature critical slowing-down of one of the degrees of freedom caused by the frustrations. It is shown that freezing of the system appears when the correlation length and relaxation time of the gauge field diverge. The Vogel–Fulcher–Tammann relation for the transition kinetics and the critical exponent for the nonlinear susceptibility, 2.5∼ t correlation function dependence on time, and explains the boson peak appearance on this curve. In addition, the function of the glass transition temperature value with cooling rate is derived; this dependence fully conforms with known experimental data
Phase transitions in K-doped MoO{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Alves, L. M. S., E-mail: leandro-fisico@hotmail.com; Lima, B. S. de; Santos, C. A. M. dos [Departamento de Engenharia de Materiais, Escola de Engenharia de Lorena-USP, Lorena, São Paulo 12602-810 (Brazil); Rebello, A.; Masunaga, S. H.; Neumeier, J. J. [Department of Physics, Montana State University, P.O. Box 173840, Bozeman, Montana 59717-3840 (United States); Leão, J. B. [NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Dr. MS 6102, Gaithersburg, Maryland 20899-6102 (United States)
2014-05-28
K{sub 0.05}MoO{sub 2} has been studied by x-ray and neutron diffractometry, electrical resistivity, magnetization, heat capacity, and thermal expansion measurements. The compound displays two phase transitions, a first-order phase transition near room temperature and a second-order transition near 54 K. Below the transition at 54 K, a weak magnetic anomaly is observed and the electrical resistivity is well described by a power-law temperature dependence with exponent near 0.5. The phase transitions in the K-doped MoO{sub 2} compound have been discussed for the first time using neutron diffraction, high resolution thermal expansion, and heat capacity measurements as a function of temperature.
Gravitational radiation from first-order phase transitions
International Nuclear Information System (INIS)
Child, Hillary L.; Giblin, John T. Jr.
2012-01-01
It is believed that first-order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles using only scalar fields, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase enhances this radiation even in the absence of a coupled fluid or turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier
Gravitational radiation from first-order phase transitions
Energy Technology Data Exchange (ETDEWEB)
Child, Hillary L.; Giblin, John T. Jr., E-mail: childh@kenyon.edu, E-mail: giblinj@kenyon.edu [Department of Physics, Kenyon College, 201 North College Road, Gambier, OH 43022 (United States)
2012-10-01
It is believed that first-order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles using only scalar fields, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase enhances this radiation even in the absence of a coupled fluid or turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier.
Phase transition signals of finite systems
International Nuclear Information System (INIS)
Duflot-Flandrois, Veronique
2001-01-01
Phase transitions are universal properties of interacting matter. They are well described if the considered system is infinite, by using standard thermodynamics. But in the case of small systems like atomic nuclei, this formalism cannot be applied anymore. Our aim is to propose a statistical mechanics approach in order to define the thermodynamical features of small open systems subject to non-saturating forces. We concentrate in particular on the definition and characterization for such systems of phase transitions belonging to the liquid gas universality class. Theoretical and experimental observables are defined to signal the occurrence and the order of this transition without any ambiguity. One of the most relevant and experimentally accessible observables consists in the study of kinetic energy fluctuations for a fixed value of the total deposited energy. In a first order phase transition such fluctuations become anomaly high and at the same time the size distribution appears to behave critically. All our results are obtained within numerical simulations of the lattice gas model with a nearest neighbors attractive interaction. Finally we check the influence of non-saturating forces, developing the specific example of the Coulomb interaction in the nucleus. Future improvements and perspectives at this work consist in the analysis of specific effects occurring in nuclei: isospin and quantum mechanics. (author) [fr
Ferroelastic Phase Transition in Pb_3(PO_4)_2 Studied by Computer Simulation
Parlinski, K.; Kawazoe, Y.
1997-01-01
A model of lead phosphate which describes its rhombohedral-monoclinic improper ferroelastic phase transition is proposed. It contains a reduced number of degrees of freedom but it is constructed consistently with symmetry changes at the phase transition. Potential parameters of the model are derived from available experimental data. The crystallites of 25× 25× 25 and 121× 121 × 25 unit cells have been simulated by the molecular-dynamics technique. The results determine the phase transition at the L point of reciprocal space, the order parameter, and the temperature behavior of monoclinic lattice parameters. In the rhombohedral phase the calculated dynamical structure factor shows inelastic peaks from which a soft branch of underdamped phonons has been established. The model has been used to calculate a diffuse scattering function which shows above T_c a maximum at an incommensurate wave vector located along the L F line of the Brillouin zone. The mentioned line is parallel to the ternary symmetry axis. On the basis of the above results we were able to vizualize the nature of the dynamical monoclinic microdomains persisting in the high-temperature rhombohedral phase. It has been shown that above T_c the fluctuations can be treated as temporary orientational monoclinic microdomains. Each type of microdomains always contains an irregular sequence of antiphase domains. Un modèle permettant de décrire la transition de phase ferroélastique impropre, rhomboédrique-monoclinique, du phosphate de plomb est proposé ci-dessous. Il est construit à partir d'un nombre réduit de degrés de liberté, tout en tenant compte des changements de symétrie caractéristique de la transition de phase. Les paramètres du modèle sont déduits quantitativement des résultats expérimentaux disponibles. La technique de dynamique moléculaire a permis de simuler le comportement des cristallites comportant 25× 25× 25 et 121× 121 × 25 mailles. Les résultats permettent de d
Reconstruction of boosted $W^{\\pm}$ and $Z^{0}$ bosons from fat jets
Heinrich, Jochen Jens; Petersen, Troels Christian
We present the reconstruction of heavily boosted $W^{\\pm}$ and $Z^{0}$ bosons from large R-parameter jets (fat jets) in all-hadronic proton-proton collisions at $\\sqrt{s} = 8$ TeV at the LHC. The electroweak gauge bosons are boosted to a degree at which their hadronic decay products are collimated enough to be reconstructed as a single fat jet. A mass-drop filtering procedure which is validated in studies on Monte Carlo (MC) samples is then applied to the fat jets with $p_{T} > 420$ GeV to suppress pileup and soft radiation. $W^{\\pm}$ and $Z^{0}$ bosons are identified based on their filtered jet mass. The efficiency of common substructure observables and event shape variables, in distinguishing between signal and QCD background is evaluated on MC and the optimized observable selection used for the training of two boosted decision trees (BDT), in order to reduce the dijet background not originating from the decay of an electroweak gauge boson. For the first BDT, signal MC has been trained against background MC...
Phase retrieval from coherent soft X-ray optics
International Nuclear Information System (INIS)
Peele, A.G.; Mancuso, A.P.; Tran, C.Q.; Paterson, D.; McNulty, I.; Hayes, J.P.; Nugent, K.A.
2005-01-01
We have recently probed the coherence of soft X-ray flux from a third generation synchrotron source [D. Paterson, B.E. Allman, P.J. McMahon, J. Lin, N. Moldovan, K.A. Nugent, I. McNulty, C.T. Chantler, C.C. Retsch, T.H.K. Irving, D.C. Mancini, Opt. Commun. 195 (2001) 79; C.Q. Tran, A.G. Peele, D. Paterson, A. Roberts, I. McNulty, K.A. Nugent, Opt. Lett. 30 (2005) 204.]. The 1-2 keV radiation exhibits transverse coherence lengths of 60 μm, which means that coherent optical effects may be observed in reasonably sized objects. We present experimental results demonstrating the creation of a phase singularity in a synchrotron beam by passing the beam through a phase mask at similarly low X-ray energies. This complements our earlier work at higher energies and demonstrates that we can now produce phase singularities across a range of energies where we have tested certain intensity-based phase recovery methods. These methods fail when the field contains phase singularities. We describe the X-ray optical vortex and outline its use as a pathological test object for phase retrieval methods. We also present recent progress towards overcoming the problem of phase retrieval in singular optics
Analyzing phase diagrams and phase transitions in networked competing populations
Ni, Y.-C.; Yin, H. P.; Xu, C.; Hui, P. M.
2011-03-01
Phase diagrams exhibiting the extent of cooperation in an evolutionary snowdrift game implemented in different networks are studied in detail. We invoke two independent payoff parameters, unlike a single payoff often used in most previous works that restricts the two payoffs to vary in a correlated way. In addition to the phase transition points when a single payoff parameter is used, phase boundaries separating homogeneous phases consisting of agents using the same strategy and a mixed phase consisting of agents using different strategies are found. Analytic expressions of the phase boundaries are obtained by invoking the ideas of the last surviving patterns and the relative alignments of the spectra of payoff values to agents using different strategies. In a Watts-Strogatz regular network, there exists a re-entrant phenomenon in which the system goes from a homogeneous phase into a mixed phase and re-enters the homogeneous phase as one of the two payoff parameters is varied. The non-trivial phase diagram accompanying this re-entrant phenomenon is quantitatively analyzed. The effects of noise and cooperation in randomly rewired Watts-Strogatz networks are also studied. The transition between a mixed phase and a homogeneous phase is identify to belong to the directed percolation universality class. The methods used in the present work are applicable to a wide range of problems in competing populations of networked agents.
Higgs boson masses in a non-minimal supersymmetric model
International Nuclear Information System (INIS)
Tiesi, Alessandro
2002-01-01
A study of the neutral Higgs spectrum in a general Z 3 -breaking Next to Minimal Supersymmetric Standard Model (NMSSM) is reported in several significant contexts. Particular attention has been devoted to the upper bound on lightest Higgs boson. In the CP-conserving case we show that the extra terms involved in the general Z 3 -breaking superpotential do not affect the upper bound which remains unchanged: it is ∼ 136 GeV when tan β = 2.7. The Spontaneous CP Violation scenario in the Z 3 -breaking NMSSM can occur at tree-level. When the phases of the fields are small the spectrum shows the lightest Higgs particle to be an almost singlet CP-odd. The second lightest particle, a doublet almost-CP-even state, still manifests the upper bound of the CP-conserving case. When the CP-violating phases are large the lightest particle is a doublet with no definite CP parity and its mass shows the usual upper bound at ∼ 136 GeV. The large number of parameters involved in the effective potential can be significantly reduced in the Infrared Quasi Fixed Point (IRQFP) resulting after solving the Renormalization Group (RG) equations assuming universality for the soft SUSY breaking masses. In the Z 3 -breaking NMSSM, unlike the Z 3 -conserving NMSSM, it is possible to find a Higgs spectrum which is still compatible with both experiment and universality at the unification scale. Because in the IRQFP regime tan β ∼ 1.8 and the stop mixing parameter is reduced then the upper bound on the lightest Higgs boson turns out to be ∼ 121 GeV. This result is compatible with experimental data coming from LEPII and might be one of the next predictions to be tested at hadron collider experiments. (author)
Solid-solid phase transitions in Fe nanowires induced by axial strain
International Nuclear Information System (INIS)
Sandoval, Luis; Urbassek, Herbert M
2009-01-01
By means of classical molecular-dynamics simulations we investigate the solid-solid phase transition from a bcc to a close-packed crystal structure in cylindrical iron nanowires, induced by axial strain. The interatomic potential employed has been shown to be capable of describing the martensite-austenite phase transition in iron. We study the stress versus strain curves for different temperatures and show that for a range of temperatures it is possible to induce a solid-solid phase transition by axial strain before the elasticity is lost; these transition temperatures are below the bulk transition temperature. The two phases have different (non-linear) elastic behavior: the bcc phase softens, while the close-packed phase stiffens with temperature. We also consider the reversibility of the transformation in the elastic regimes, and the role of the strain rate on the critical strain necessary for phase transition.
Introduction to interacting boson model
International Nuclear Information System (INIS)
Goutte, D.
1986-01-01
A very simple presentation of the interacting boson model is first given. The two computerized models which are presented allow, with few parameters, to reproduce an impressive quantity of data characterizing the deformed nuclei. Their excitation spectra, the reduced transition probabilities, the quadrupolar moments, the two nucleon transfer experiment results, ... Then a specific application of the model is given: radial extension reproduction of nuclear functions. It is shown first how the electron inelastic scattering allows to measure observables related to these radial functions, the transition charge densities, then, on some examples, how the model allows to reproduce them [fr
Color superconductivity. Phase diagrams and Goldstone bosons in the color-flavor locked phase
Energy Technology Data Exchange (ETDEWEB)
Kleinhaus, Verena
2009-04-29
The phase diagram of strongly interacting matter is studied with great experimental and theoretical effort and is one of the most fascinating research areas in modern particle physics. It is believed that color superconducting phases, in which quarks form Cooper pairs, appear at very high densities and low temperatures. Such phases could appear in the cores of neutron stars. In this work color superconducting phases are studied within the Nambu-Jona-Lasinio model. First of all, the phase diagram of neutral matter in beta equilibrium is calculated for two different diquark couplings. To this end, we determine the dynamical quark masses self-consistently together with the order parameters of color superconductivity. The interplay between neutrality and quark masses results in an interesting phase structure, in particular for the smaller diquark coupling. In the following, we additionally include a conserved lepton number to map the situation in the first few seconds of the evolution of a protoneutron star when neutrinos are trapped. This has a huge influence on the phase structure and favors the 2SC phase compared to the CFL phase. In the second part of this work we concentrate on the CFL phase which is characterized by a special symmetry breaking pattern. The properties of the resulting nine pseudoscalar Goldstone bosons (GB) are studied by solving the Bethe-Salpeter equation for quark-quark scattering. The GB are the lowest-lying excitations in the CFL phase and therefore play an important role for the thermodynamics of the system. The properties of the GB can also be described by the low-energy effective theory (LEET) for the CFL phase. There the respective low-energy constants are derived for asymptotically high densities where the strong force is weak and can be treated perturbatively. Our aim is the comparison of our results with these predictions, on the one hand to check our model in the weak-coupling limit and on the other hand to derive information about
Color superconductivity: Phase diagrams and Goldstone bosons in the color-flavor locked phase
International Nuclear Information System (INIS)
Kleinhaus, Verena
2009-01-01
The phase diagram of strongly interacting matter is studied with great experimental and theoretical effort and is one of the most fascinating research areas in modern particle physics. It is believed that color superconducting phases, in which quarks form Cooper pairs, appear at very high densities and low temperatures. Such phases could appear in the cores of neutron stars. In this work color superconducting phases are studied within the Nambu-Jona-Lasinio model. First of all, the phase diagram of neutral matter in beta equilibrium is calculated for two different diquark couplings. To this end, we determine the dynamical quark masses self-consistently together with the order parameters of color superconductivity. The interplay between neutrality and quark masses results in an interesting phase structure, in particular for the smaller diquark coupling. In the following, we additionally include a conserved lepton number to map the situation in the first few seconds of the evolution of a protoneutron star when neutrinos are trapped. This has a huge influence on the phase structure and favors the 2SC phase compared to the CFL phase. In the second part of this work we concentrate on the CFL phase which is characterized by a special symmetry breaking pattern. The properties of the resulting nine pseudoscalar Goldstone bosons (GB) are studied by solving the Bethe-Salpeter equation for quark-quark scattering. The GB are the lowest-lying excitations in the CFL phase and therefore play an important role for the thermodynamics of the system. The properties of the GB can also be described by the low-energy effective theory (LEET) for the CFL phase. There the respective low-energy constants are derived for asymptotically high densities where the strong force is weak and can be treated perturbatively. Our aim is the comparison of our results with these predictions, on the one hand to check our model in the weak-coupling limit and on the other hand to derive information about
MAXI/GSC detection of a hard-to-soft transition of NS-LMXB GS 1826-238
Nakahira, S.; Mihara, T.; Sugizaki, M.; Serino, M.; Morii, M.; Sugimoto, J.; Takagi, T.; Yoshikawa, A.; Matsuoka, M.; Kawai, N.; Yoshii, T.; Tachibana, Y.; Ueno, S.; Tomida, H.; Kimura, M.; Ishikawa, M.; Nakagawa, Y. E.; Negoro, H.; Nakajima, M.; Fukushima, K.; Onodera, T.; Suzuki, K.; Fujita, M.; Namba, T.; Honda, F.; Yoshida, A.; Sakamoto, T.; Kawakubo, Y.; Ohtsuki, H.; Tsunemi, H.; Uchida, D.; Ueda, Y.; Shidatsu, M.; Kawamuro, T.; Hori, T.; Kawagoe, A.; Tsuboi, Y.; Yamauchi, M.; Morooka, Y.; Yamaoka, K.
2014-06-01
We report on a hard-to-soft spectral transition of an X-ray burster GS 1826-238 detected with MAXI/GSC. This source had been consistently observed in the hard state for more than 25 years since the discovery in 1988 (Tanaka 1989, Barret et al. ...
Diffusionless phase transitions and related structures in oxides
International Nuclear Information System (INIS)
Boulesteix, C.
1992-01-01
The relative importance of oxides in the field of materials science has been spectacularly increasing during the last twenty years. First the study of ferroelectrics kept the attention of scientists. Nevertheless this domain is far from being worked out and a lot of new results and of new fields of interest were recently discovered. Other ferroic oxides, especially ferroelastics, have also been the subject of a very great number of new results. In these cases the properties of oxides are at room temperature very tightly related to the phase transition that is generally occurring a few hundred of degrees above this room temperature. In many other cases also properties of oxides can be related to the existence of a phase transition or to a rather similar phenomenon. This book has been specially devoted to the study of the properties of oxides which are in some way related to the existence of a phase transition. The first chapters are focussed on general considerations: the first one is devoted to a general study of phase transitions, the second one to the twinning phenomenon which is of special interest for many oxides. Chapters 3 and 4 are focussed on ferroelectric and ferroelastic materials. These four chapters consitute the first part of the book. Chapters 5 to 8 are devoted to the study of oxides of special interest which have some of their properties related to a phase transition or to a rather similar phenomenon: rare earth oxides, oxides with a diffuse phase transition, zirconia and alumina systems, tungsten oxides and their relatives. These four chapters constitute the second part of the book. (orig.)
Rare Z boson decays to a hidden sector
Blinov, Nikita; Izaguirre, Eder; Shuve, Brian
2018-01-01
We demonstrate that rare decays of the Standard Model Z boson can be used to discover and characterize the nature of new hidden-sector particles. We propose new searches for these particles in soft, high-multiplicity leptonic final states at the Large Hadron Collider. The proposed searches are sensitive to low-mass particles produced in Z decays, and we argue that these striking signatures can shed light on the hidden-sector couplings and mechanism for mass generation.
Discontinuous structural phase transition of liquid metal and alloys (2)
International Nuclear Information System (INIS)
Wang, Li; Liu, Jiantong
2004-01-01
The diameter (d f ) of diffusion fluid cluster before and after phase transition has been calculated in terms of the paper ''Discontinuous structural phase transition of liquid metal and alloy (1)'' Physics Letters. A 326 (2004) 429-435, to verify quantitatively the discontinuity of structural phase transition; the phenomena of thermal contraction and thermal expansion during the phase transition, together with the evolution model of discontinuous structural phase transition are also discussed in this Letter to explore further the nature of structural transition; In addition, based on the viscosity experimental result mentioned in paper [Y. Waseda, The Structure of Non-Crystalline Materials--Liquids and Amorphous Solids, McGraw-Hill, New York, 1980], we present an approach to draw an embryo of the liquid-liquid (L-L) phase diagram for binary alloys above liquidus in the paper, expecting to guide metallurgy process so as to improve the properties of alloys. The idea that controls amorphous structure and its properties by means of the L-L phase diagram for alloys and by the rapid cooling technique to form the amorphous alloy has been brought forward in the end
Dimension changing phase transitions in instanton crystals
International Nuclear Information System (INIS)
Kaplunovsky, Vadim; Sonnenschein, Jacob
2014-01-01
We investigate lattices of instantons and the dimension-changing transitions between them. Our ultimate goal is the 3D→4D transition, which is holographically dual to the phase transition between the baryonic and the quarkyonic phases of cold nuclear matter. However, in this paper (just as in http://dx.doi.org/10.1007/JHEP11(2012)047) we focus on lower dimensions — the 1D lattice of instantons in a harmonic potential V∝M 2 2 x 2 2 +M 3 2 x 2 2 +M 4 2 x 4 2 , and the zigzag-shaped lattice as a first stage of the 1D→2D transition. We prove that in the low- and moderate-density regimes, interactions between the instantons are dominated by two-body forces. This drastically simplifies finding the ground state of the instantons’ orientations, so we made a numeric scan of the whole orientation space instead of assuming any particular ansatz. We find that depending on the M 2 /M 3 /M 4 ratios, the ground state of instanton orientations can follow a wide variety of patterns. For the straight 1D lattices, we found orientations periodically running over elements of a ℤ 2 , Klein, prismatic, or dihedral subgroup of the SU(2)/ℤ 2 , as well as irrational but link-periodic patterns. For the zigzag-shaped lattices, we detected 4 distinct orientation phases — the anti-ferromagnet, another abelian phase, and two non-abelian phases. Allowing the zigzag amplitude to vary as a function of increasing compression force, we obtained the phase diagrams for the straight and zigzag-shaped lattices in the (force,M 3 /M 4 ), (chemical potential,M 3 /M 4 ), and (density,M 3 /M 4 ) planes. Some of the transitions between these phases are second-order while others are first-order. Our techniques can be applied to other types of non-abelian crystals
Novel phase transitions in B-site doped manganites
Energy Technology Data Exchange (ETDEWEB)
Popovic, Z.V. [Institute of Physics, P.O. Box 68, 11080 Belgrade/Zemun (Serbia and Montenegro)]. E-mail: zoran.popovic@phy.bg.ac.yu; Cantarero, A. [Materials Science Institute, University of Valencia, P.O. Box 22085, 46071 Valencia (Spain); Thijssen, W.H.A. [Kamerlingh Onnes Laboratorium, Leiden University, Postbus 9504, 2300 RA Leiden (Netherlands); Paunovic, N. [Institute of Physics, P.O. Box 68, 11080 Belgrade/Zemun (Serbia and Montenegro); Dohcevic-Mitrovic, Z. [Institute of Physics, P.O. Box 68, 11080 Belgrade/Zemun (Serbia and Montenegro); Sapina, F. [Materials Science Institute, University of Valencia, P.O. Box 22085, 46071 Valencia (Spain)
2005-04-30
We have examined the infrared reflectivity and the electrical resistivity of La{sub 1-} {sub x} [Sr(Ba)] {sub x} Mn{sub 1-} {sub z} [Cu(Zn)] {sub z} O{sub 3} samples in ferromagnetic metallic and insulator regime. Several phase transitions are observed, the most obvious being the transition from a ferromagnetic metallic to a ferromagnetic insulator phase that is related to the formation of short-range orbitally ordered domains. The temperature T {sub 1} of the phase transition is dependent on doping concentration and for optimally doped samples ({approx}32% of Mn{sup 4+} ions) we have found T {sub 1}{approx}0.93 T {sub C}.
Baryon inhomogeneity from the cosmic quark-hadron phase transition
International Nuclear Information System (INIS)
Kurki-Suonio, H.
1991-01-01
We discuss the generation of inhomogeneity in the baryon-number density during the cosmic quark-hadron phase transition. We use a simple model with thin-wall phase boundaries and ideal-gas equations of state. The nucleation of the phase transition introduces a new distance scale into the universe which will be the scale of the generated inhomogeneity. We review the estimate of this scale. During the transition baryon number is likely to collect onto a layer at the phase boundary. These layers may in the end be deposited as small regions of very high baryon density. 21 refs., 1 fig
Magnetodynamical resonance near the low-temperature phase transition in ErFeO3
International Nuclear Information System (INIS)
Dan'shin, N.K.; Kovtun, N.M.; Sdvizhkov, M.A.
1986-01-01
Magnetodynamical resonance (MDR) near low-temperature phase transition (PT) in erbium ortoferrite is investigated. At temperature below 4K (PT temperature) pt can be induced by a magnetic field. It is revealed that PT is accompained by partialsoftening of one of the magnetic resonance MR) branches. Besides MR soft mode resonance absorption was observed. This absorption is shown to be related to the excitation in a sample of dielectric resonance (DR). Essential differences of MDR near PT in ErFeO 3 are as follows: interaction between MR abd DR at PT takes place under softening of all interacting models; ErFeO 3 is characterized by a high value of permittivity epslon and by considerable anisotropy epsilon and magnetic permeability
Pressure induced phase transitions in ceramic compounds containing tetragonal zirconia
Energy Technology Data Exchange (ETDEWEB)
Sparks, R.G.; Pfeiffer, G.; Paesler, M.A.
1988-12-01
Stabilized tetragonal zirconia compounds exhibit a transformation toughening process in which stress applied to the material induces a crystallographic phase transition. The phase transition is accompanied by a volume expansion in the stressed region thereby dissipating stress and increasing the fracture strength of the material. The hydrostatic component of the stress required to induce the phase transition can be investigated by the use of a high pressure technique in combination with Micro-Raman spectroscopy. The intensity of Raman lines characteristic for the crystallographic phases can be used to calculate the amount of material that has undergone the transition as a function of pressure. It was found that pressures on the order of 2-5 kBar were sufficient to produce an almost complete transition from the original tetragonal to the less dense monoclinic phase; while a further increase in pressure caused a gradual reversal of the transition back to the original tetragonal structure.
Phase transitions in liquids with directed intermolecular bonding
Son, L.; Ryltcev, R.
2005-01-01
Liquids with quasi - chemical bonding between molecules are described in terms of vertex model. It is shown that this bonding results in liquid - liquid phase transition, which occurs between phases with different mean density of intermolecular bonds. The transition may be suggested to be a universal phenomena for those liquids.
G-Boson renormalizations and mixed symmetry states
International Nuclear Information System (INIS)
Scholten, O.
1986-01-01
In the IBA model the low-lying collective states are described in terms of a system of interacting s- and d-bosons. A boson can be interpreted as corresponding to collective J=0 or J=2 fermion pair states. As such the IBA model space can be seen as only a small subsector of the full shell model space. For medium heavy nuclei such a truncation of the model space is necessary to make calculations feasible. As is well known truncations of a model space make it necessary to renormalize the model parameters. In this work some renormalizations of the Hamiltonian and the E2 transition operator will be discussed. Special attention will be given to the implication of these renormalizations for the properties of mixed symmetry states. The effects of renormalization are obtained by considering the influence of fermion pair states that have been omitted from the model basis. Here the authors focus attention on the effect of the low-lying two particle J=4 state, referred to as g-boson or G-pair state. Renormalizations of the d-boson energy, the E2 effective charges, and symmetry force are discussed
Boosted W-Boson Identification at sqrt{s} = 8 TeV with the ATLAS Detector
Delitzsch, Chris Malena; The ATLAS collaboration
2015-01-01
The high center-of-mass energy of the $pp$ collisions at the LHC enables searches for new particles with masses at the TeV scale. These heavy resonances can decay to final states with high $p_{\\rm T}$ $W$- and $Z$-bosons. The hadronic decay modes of these bosons are of special interest of the potential increase in sensitivity for measurements and searches. However, the cross-section of background events originating from light-quark and gluons jets is orders of magnitudes higher than the production of $W$-bosons. At large transverse-momentum, the decay products of the boson are collimated into one individual large-radius jets. Due to the high-luminosity conditions, soft particles unrelated to the hard scattering can contaminate the jets in the detector resulting in a diminished mass resolution. To enhance the sensitivity to new physics processes and to mitigate the influence of pile-up, jet grooming algorithms like trimming, pruning and mass-drop filtering have been designed. In addition, substructure techniqu...
Energy transition and phasing out nuclear
International Nuclear Information System (INIS)
Laponche, Bernard
2013-05-01
In the first part of this report, the author outlines and comments the need of an energy transition in the world: overview of world challenges (world energy consumption and its constraints, a necessary energy transition, new actors and new responsibilities), and describes the German example of an energy transition policy. In the second part, he presents and discusses the main reasons for phasing out nuclear: description of a nuclear plant operation (fission and chain reaction, heat production, production of radioactive elements, how to stop a nuclear reactor), safety and risk issues (protection arrangements, risk and consequence of a nuclear accident), issue of radioactive wastes, relationship between civil techniques and proliferation of nuclear weapons. In a third part, the author proposes an overview of the energy issue in France: final energy consumption, electricity production and consumption, primary energy consumption, characteristics of the French energy system (oil dependency, electricity consumption, and high share of nuclear energy in electricity production). In a last part, the author addresses the issue of energy transition in a perspective of phasing out nuclear: presentation of the Negawatt scenario, assessments made by Global Chance, main programmes of energy transition
Precision Analysis of the Lightest MSSM Higgs Boson at Future Colliders
Ellis, Jonathan Richard; Olive, Keith A; Weiglein, Georg; Ellis, John; Heinemeyer, Sven; Olive, Keith A.; Weiglein, Georg
2003-01-01
We investigate the sensitivity of observables measurable in e^+ e^-, gamma gamma and mu^+ mu^- collisions for distinguishing the properties of the light neutral CP-even Higgs boson in the minimal supersymmetric extension of the Standard Model (MSSM) from those of a Standard Model (SM) Higgs boson with the same mass. We explore first the available parameter space in the constrained MSSM (CMSSM), with universal soft supersymmetry-breaking parameters, incorporating the most recent direct limits on sparticle and Higgs masses, the indirect constraints from b to s gamma and g_mu - 2, and the cosmological relic density. We calculate the products of the expected CMSSM Higgs production cross sections and decay branching ratios sigma X B normalized by the corresponding values expected for those of a SM Higgs boson of the same mass. The results are compared with the precisions expected at each collider, and allow for a direct comparison of the different channels. The measurements in the Higgs sector are found to provide...
Heat capacity characterization at phase transition temperature of Agl superionic
International Nuclear Information System (INIS)
Widowati, Arie
2000-01-01
The phase transition of Agl superionic conductor was investigated by calorometric. A single phase transition was found at (153±5) o C which corresponds to the α - β transition. Calorimetric measurement showed an anomalously high heat capacity with a large discontinues change in the Arrhenius plot, was found above the transition temperature of β - α phase. The maximum heat capacity was found to be ±19.7 cal/gmol. Key words : superionic conductor, thermal capacity
Generalized transport model for phase transition with memory
International Nuclear Information System (INIS)
Chen, Chi; Ciucci, Francesco
2013-01-01
A general model for phenomenological transport in phase transition is derived, which extends Jäckle and Frisch model of phase transition with memory and the Cahn–Hilliard model. In addition to including interfacial energy to account for the presence of interfaces, we introduce viscosity and relaxation contributions, which result from incorporating memory effect into the driving potential. Our simulation results show that even without interfacial energy term, the viscous term can lead to transient diffuse interfaces. From the phase transition induced hysteresis, we discover different energy dissipation mechanism for the interfacial energy and the viscosity effect. In addition, by combining viscosity and interfacial energy, we find that if the former dominates, then the concentration difference across the phase boundary is reduced; conversely, if the interfacial energy is greater then this difference is enlarged.
Thermodynamic phase transition of a black hole in rainbow gravity
Directory of Open Access Journals (Sweden)
Zhong-Wen Feng
2017-09-01
Full Text Available In this letter, using the rainbow functions that were proposed by Magueijo and Smolin, we investigate the thermodynamics and the phase transition of rainbow Schwarzschild black hole. First, we calculate the rainbow gravity corrected Hawking temperature. From this modification, we then derive the local temperature, free energy, and other thermodynamic quantities in an isothermal cavity. Finally, we analyze the critical behavior, thermodynamic stability, and phase transition of the rainbow Schwarzschild black hole. The results show that the rainbow gravity can stop the Hawking radiation in the final stages of black holes' evolution and lead to the remnants of black holes. Furthermore, one can observe that the rainbow Schwarzschild black hole has one first-order phase transition, two second-order phase transitions, and three Hawking–Page-type phase transitions in the framework of rainbow gravity theory.
International Nuclear Information System (INIS)
Rosciszewski, K.
1979-01-01
The phase transitions between liquids and several of the simplest liquid crystalline phases (nematic, cholesteric, and the simplest types of smectic A and smectic C) were studied from the point of view of the group-theoretical arguments of Landau theory. It was shown that the only possible candidates for second-order phase transitions are those between nematic and smectic A, between centrosymmetric nematic and smectic C and between centrosymmetric smectic A and smectic C. Simple types of density functions for liquid crystalline phases are proposed. (author)
Fermion condensation quantum phase transition versus conventional quantum phase transitions
International Nuclear Information System (INIS)
Shaginyan, V.R.; Han, J.G.; Lee, J.
2004-01-01
The main features of fermion condensation quantum phase transition (FCQPT), which are distinctive in several aspects from that of conventional quantum phase transition (CQPT), are considered. We show that in contrast to CQPT, whose physics in quantum critical region is dominated by thermal and quantum fluctuations and characterized by the absence of quasiparticles, the physics of a Fermi system near FCQPT or undergone FCQPT is controlled by the system of quasiparticles resembling the Landau quasiparticles. Contrary to the Landau quasiparticles, the effective mass of these quasiparticles strongly depends on the temperature, magnetic fields, density, etc. This system of quasiparticles having general properties determines the universal behavior of the Fermi system in question. As a result, the universal behavior persists up to relatively high temperatures comparatively to the case when such a behavior is determined by CQPT. We analyze striking recent measurements of specific heat, charge and heat transport used to study the nature of magnetic field-induced QCP in heavy-fermion metal CeCoIn 5 and show that the observed facts are in good agreement with our scenario based on FCQPT and certainly seem to rule out the critical fluctuations related with CQPT. Our general consideration suggests that FCQPT and the emergence of novel quasiparticles near and behind FCQPT and resembling the Landau quasiparticles are distinctive features intrinsic to strongly correlated substances
Dynamical Symmetries and Causality in Non-Equilibrium Phase Transitions
Directory of Open Access Journals (Sweden)
Malte Henkel
2015-11-01
Full Text Available Dynamical symmetries are of considerable importance in elucidating the complex behaviour of strongly interacting systems with many degrees of freedom. Paradigmatic examples are cooperative phenomena as they arise in phase transitions, where conformal invariance has led to enormous progress in equilibrium phase transitions, especially in two dimensions. Non-equilibrium phase transitions can arise in much larger portions of the parameter space than equilibrium phase transitions. The state of the art of recent attempts to generalise conformal invariance to a new generic symmetry, taking into account the different scaling behaviour of space and time, will be reviewed. Particular attention will be given to the causality properties as they follow for co-variant n-point functions. These are important for the physical identification of n-point functions as responses or correlators.
Universal phase transition in community detectability under a stochastic block model.
Chen, Pin-Yu; Hero, Alfred O
2015-03-01
We prove the existence of an asymptotic phase-transition threshold on community detectability for the spectral modularity method [M. E. J. Newman, Phys. Rev. E 74, 036104 (2006) and Proc. Natl. Acad. Sci. (USA) 103, 8577 (2006)] under a stochastic block model. The phase transition on community detectability occurs as the intercommunity edge connection probability p grows. This phase transition separates a subcritical regime of small p, where modularity-based community detection successfully identifies the communities, from a supercritical regime of large p where successful community detection is impossible. We show that, as the community sizes become large, the asymptotic phase-transition threshold p* is equal to √[p1p2], where pi(i=1,2) is the within-community edge connection probability. Thus the phase-transition threshold is universal in the sense that it does not depend on the ratio of community sizes. The universal phase-transition phenomenon is validated by simulations for moderately sized communities. Using the derived expression for the phase-transition threshold, we propose an empirical method for estimating this threshold from real-world data.
Multipartite entanglement characterization of a quantum phase transition
Costantini, G.; Facchi, P.; Florio, G.; Pascazio, S.
2007-07-01
A probability density characterization of multipartite entanglement is tested on the one-dimensional quantum Ising model in a transverse field. The average and second moment of the probability distribution are numerically shown to be good indicators of the quantum phase transition. We comment on multipartite entanglement generation at a quantum phase transition.
Multipartite entanglement characterization of a quantum phase transition
Energy Technology Data Exchange (ETDEWEB)
Costantini, G [Dipartimento di Fisica, Universita di Bari, I-70126 Bari (Italy); Facchi, P [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari (Italy); Florio, G [Dipartimento di Fisica, Universita di Bari, I-70126 Bari (Italy); Pascazio, S [Dipartimento di Fisica, Universita di Bari, I-70126 Bari (Italy)
2007-07-13
A probability density characterization of multipartite entanglement is tested on the one-dimensional quantum Ising model in a transverse field. The average and second moment of the probability distribution are numerically shown to be good indicators of the quantum phase transition. We comment on multipartite entanglement generation at a quantum phase transition.
Phase transitions and glass transition in a hyperquenched silica–alumina glass
DEFF Research Database (Denmark)
Zhang, Y.F.; Zhao, D.H.; Yue, Yuanzheng
2017-01-01
We investigate phase transitions, glass transition, and dynamic behavior in the hyperquenched 69SiO2–31Al2O3 (mol%) glass (SA glass). Upon reheating, the SA glass exhibits a series of thermal responses. Subsequent to the sub-Tg enthalpy release, the glass undergoes a large jump in isobaric heat...... capacity (ΔCp) during glass transition, implying the fragile nature of the SA glass. The mullite starts to form before the end of glass transition, indicating that the SA glass is extremely unstable against crystallization. After the mullite formation, the remaining glass phase exhibits an increased Tg...... and a suppressed ΔCp. The formation of cristobalite at 1553 K indicates the dominance of silica in the remaining glass matrix. The cristobalite gradually re-melts as the isothermal heat-treatment temperature is raised from 1823 to 1853 K, which is well below the melting point of cristobalite, while the amount...
Calorimetric Study of Phase Transitions Involving Twist-Grain-Boundary TGB{A} and TGB{C} Phases
Navailles, L.; Garland, C. W.; Nguyen, H. T.
1996-09-01
High-resolution calorimetry has been used to determine the heat capacity and latent heat associated with phase transitions in the homologous series of chiral liquid crystals nF_2BTFO_1M_7 [ 3-fluoro-4(1-methylheptyloxy)4'-(4''-alkoxy-2'', 3''-difluorobenzoyloxy)tolane] . These compounds exhibit smectic-C^* (SmC^*), twist-grain-boundary (TGBA for n=10, TGBC for n=11, 12) and cholesteric (N^*) phases. All the phase transitions are first order with small to moderate latent heats. There is a large rounded excess heat capacity peak in the N^* phase that is consistent with the predicted appearance of short-range TGB order (chiral line liquid character). This is analogous to the development of an Abrikosov flux vortex liquid in type-II superconductors. Both the n=11 and 12 homologs exhibit two closely spaced transitions in the region where a single TGBC - N^* transition was expected. This suggests the existence of two thermodynamically distinct TGBC phases. Des exprériences de calorimétrie haute résolution ont été réalisées pour déterminer les chaleurs spécifiques et les chaleurs latentes associées aux transitions de phase des homologues de la série crystal liquide nF_2BTFO_1M_7: 3-fluoro-4[1-methyl-heptyloxy]4'-(4''-alcoxy-2'', 3''-difluorobenzoyloxy)tolanes. Ces produits présentent la phase smectique C^* (SmC^*), les phases à torsion par joint de grain (TGBA pour n=10 et TGBC pour n=11, 12) et la phase cholestérique (N^*). Toutes les transitions de phase sont du premier ordre. La chaleur latente associée à ces transitions est faibles ou modérée. Nous observons, dans la phase N^*, un grand pic arrondi qui est en accord avec les prédictions de l'apparition d'un ordre TGB à courte distance (liquide de ligne de dislocation). Ce phénomène est l'analogue du liquide de vortex dans les supraconducteurs de type II. Les composés n=11 et 12 présentent, dans la région où nous attendions une transition TGBC - N^* unique, deux transitions sur un très faible
The problem of phase transitions in statistical mechanics
International Nuclear Information System (INIS)
Martynov, Georgii A
1999-01-01
The first part of this review deals with the single-phase approach to the statistical theory of phase transitions. This approach is based on the assumption that a first-order phase transition is due to the loss of stability of the parent phase. We demonstrate that it is practically impossible to find the coordinates of the transition points using this criterion in the framework of the global Gibbs theory which describes the state of the entire macroscopic system. On the basis of the Ornstein-Zernike equation we formulate a local approach that analyzes the state of matter inside the correlation sphere of radius R c ∼ 10 A. This approach is proved to be as rigorous as the Gibbs theory. In the context of the local approach we formulate a criterion that allows finding the transition points without calculating the chemical potential and the pressure of the second conjugate phase. In the second part of the review we consider second-order phase transitions (critical phenomena). The Kadanoff-Wilson theory of critical phenomena is analyzed, based on the global Gibbs approach. Again we use the Ornstein-Zernike equation to formulate a local theory of critical phenomena. With regard to experimentally established quantities this theory yields precisely the same results as the Kadanoff-Wilson theory; secondly, the local approach allows the prediction of many previously unknown details of critical phenomena, and thirdly, the local approach paves the way for constructing a unified theory of liquids that will describe the behavior of matter not only in the regular domain of the phase diagram, but also at the critical point and in its vicinity. (reviews of topical problems)
Wei, Ran; Sun, Huan; Chen, Chen; Tao, Juan; Li, Fushan
2018-03-01
Fe-Co-Ni-Si-B high entropy amorphous alloys composites (HEAACs), which containing high entropy solid solution phase in amorphous matrix, show good soft magnetic properties and bending ductility even in optimal annealed state, were successfully developed by melt spinning method. The crystallization phase of the HEAACs is solid solution phase with body centered cubic (BCC) structure instead of brittle intermetallic phase. In addition, the BCC phase can transformed into face centered cubic (FCC) phase with temperature rise. Accordingly, Fe-Co-Ni-Si-B high entropy alloys (HEAs) with FCC structure and a small amount of BCC phase was prepared by copper mold casting method. The HEAs exhibit high yield strength (about 1200 MPa) and good plastic strain (about 18%). Meanwhile, soft magnetic characteristics of the HEAs are largely reserved from HEAACs. This work provides a new strategy to overcome the annealing induced brittleness of amorphous alloys and design new advanced materials with excellent comprehensive properties.
International Nuclear Information System (INIS)
Niyaz, P.
1993-01-01
Quantum Monte Carlo techniques were used to study two quantum many-body systems, the one-dimensional extended boson-Hubbard Hamiltonian, a model of superfluid-insulator quantum phase transitions, and the two-dimensional Holstein Model, a model for electron-phonon interactions. For the extended boson-Hubbard model, the authors studied the ground state properties at commensurate filling (density = 1) and half-integer filling (density = 1/2). At commensurate filling, the system has two possible insulating phases for strong coupling. If the on-site repulsion dominates, the system freezes into an insulating phase where each site is singly occupied. If the intersite repulsion dominates, doubly occupied and empty sites alternate. At weak coupling, the system becomes a superfluid. The authors investigated the order of phase transitions between these different phases. At half-integer filling, the authors found one strong coupling insulating phase, where singly occupied and empty sites alternate, and a weak coupling superfluid phase. The authors also investigated the possibility of a supersolid phase and found no clear evidence of such a new phase. For the electron-phonon (Holstein) model, the authors focused on the finite temperature phase transition from a metallic state to an insulating charge density wave (CDW) state as the temperature is lowered. The authors present the first calculation of the spectral density from Monte Carlo data for this system. The authors also investigated the formation of a CDW state as a function of various parameters characterizing the electron-phonon interactions. Using these numerical results as benchmarks, the authors then investigated different levels of Migdal approximations. The authors found the solutions of a set of gapped Migdal-Eliashberg equations agreed qualitatively with the Monte Carlo results
Higgs mass prediction with non-universal soft supersymmetry breaking in MSSM
International Nuclear Information System (INIS)
Codoban, S.; Jurcisin, M.; Kazakov, D.
2001-01-01
In the framework of the MSSM (Minimal supersymmetric extension of the standard model) the non-universal boundary conditions of soft SUSY breaking parameters are considered. Taking as input the top, bottom and Z-boson masses, the values of the gauge couplings at the EW scale and the infrared quasi-fixed points for Yukawa couplings and the soft parameters the mass of the lightest CP-even Higgs boson is found to be m h = 92.7 -4.9 +10 ± 5 ± 0.4 GeV/c 2 for the low tan(β) case and m h 125.7 -9.0 +6.4 ± 5 ± 0.4 GeV/c 2 (μ > 0) or m h 125.4 -9.0 +6.6 ± 5 ± 0.4 Ge V/c 2 (μ < 0) in the case of large tan(β). (authors)
Stavrou, E; Tsiantos, C; Tsopouridou, R D; Kripotou, S; Kontos, A G; Raptis, C; Capoen, B; Bouazaoui, M; Turrell, S; Khatir, S
2010-05-19
Raman scattering and differential scanning calorimetry (DSC) measurements have been carried out on four mixed tellurium-zinc oxide (TeO(2))(1 - x)(ZnO)(x) (x = 0.1, 0.2, 0.3, 0.4) glasses under variable temperature, with particular attention being given to the respective glass transition region. From the DSC measurements, the glass transition temperature T(g) has been determined for each glass, showing a monotonous decrease of T(g) with increasing ZnO content. The Raman study is focused on the low-frequency band of the glasses, the so-called boson peak (BP), whose frequency undergoes an abrupt decrease at a temperature T(d) very close to the respective T(g) values obtained by DSC. These results show that the BP is highly sensitive to dynamical effects over the glass transition and provides a means for an equally reliable (to DSC) determination of T(g) in tellurite glasses and other network glasses. The discontinuous temperature dependence of the BP frequency at the glass transition, along with the absence of such a behaviour by the high-frequency Raman bands (due to local atomic vibrations), indicates that marked changes of the medium range order (MRO) occur at T(g) and confirms the correlation between the BP and the MRO of glasses.
International Nuclear Information System (INIS)
Stavrou, E; Tsiantos, C; Tsopouridou, R D; Kripotou, S; Kontos, A G; Raptis, C; Capoen, B; Bouazaoui, M; Turrell, S; Khatir, S
2010-01-01
Raman scattering and differential scanning calorimetry (DSC) measurements have been carried out on four mixed tellurium-zinc oxide (TeO 2 ) 1-x (ZnO) x (x = 0.1, 0.2, 0.3, 0.4) glasses under variable temperature, with particular attention being given to the respective glass transition region. From the DSC measurements, the glass transition temperature T g has been determined for each glass, showing a monotonous decrease of T g with increasing ZnO content. The Raman study is focused on the low-frequency band of the glasses, the so-called boson peak (BP), whose frequency undergoes an abrupt decrease at a temperature T d very close to the respective T g values obtained by DSC. These results show that the BP is highly sensitive to dynamical effects over the glass transition and provides a means for an equally reliable (to DSC) determination of T g in tellurite glasses and other network glasses. The discontinuous temperature dependence of the BP frequency at the glass transition, along with the absence of such a behaviour by the high-frequency Raman bands (due to local atomic vibrations), indicates that marked changes of the medium range order (MRO) occur at T g and confirms the correlation between the BP and the MRO of glasses.
Martensitic phase transitions in Co-0.85 at % Fe
International Nuclear Information System (INIS)
Prem, M.
1997-12-01
Co-0.85at%Fe shows the two martensitic phase transitions hcp-dhcp and dhcp-fcc. The lattice dynamics of Co-0.85at%Fe was investigated by the means of inelastic neutron scattering at a series of temperatures up to 750K in order to understand the two martensitic phase transitions of this system. In all of the measured phonon branches anomalies were neither found near the hcp-dhcp phase transition nor going through the dhcp-fcc transition. Lattice-parameter scans were performed through the whole temperature range. Diffuse neutron scattering revealed a lattice parameter shift between the dhcp and fcc phase of ∼0.4 % measured at the same temperature. This was possible because the system shows a wide temperature hysteresis at the two phase transitions. In the temperature region of coexistence of dhcp and fcc phase diffuse satellites arose near the (111)fcc Bragg peak (which is equivalent to the (00.2)dhcp peak). Their intensity varied in accordance to the volume fraction of the phases but vanished on changing wavelength. The elastic measurements were performed at the Austrian triple axis spectrometer VALSE located at the Laboratoire Leon Brillouin (LLB) in Saclay (F); the inelastic measurements were performed at the spectrometers IN3 and INS of the Institute Laue Langevin (ILL) in Grenoble (F). (author)
Evans, Arthur A.
2011-01-01
This dissertation contains within an exploration of the interactions between various soft matter systems and an environmental stimulus. The natural case studies for examining soft matter using the language of thermodynamics and phase transitions are biological constituents, from slender filaments to entire collections of organisms. We first present a brief overview of soft condensed matter, couching the thesis in terms of states of matter and preparing the stage for using continuum mechanics ...
Basler, P.; Mühlleitner, M.; Wittbrodt, J.
2018-03-01
We investigate the strength of the electroweak phase transition (EWPT) within the CP-violating 2-Higgs-Doublet Model (C2HDM). The 2HDM is a simple and well-studied model, which can feature CP violation at tree level in its extended scalar sector. This makes it, in contrast to the Standard Model (SM), a promising candidate for explaining the baryon asymmetry of the universe through electroweak baryogenesis. We apply a renormalisation scheme which allows efficient scans of the C2HDM parameter space by using the loop-corrected masses and mixing matrix as input parameters. This procedure enables us to investigate the possibility of a strong first order EWPT required for baryogenesis and study its phenomenological implications for the LHC. Like in the CP-conserving (real) 2HDM (R2HDM) we find that a strong EWPT favours mass gaps between the non-SM-like Higgs bosons. These lead to prominent final states comprised of gauge+Higgs bosons or pairs of Higgs bosons. In contrast to the R2HDM, the CP-mixing of the C2HDM also favours approximately mass degenerate spectra with dominant decays into SM particles. The requirement of a strong EWPT further allows us to distinguish the C2HDM from the R2HDM using the signal strengths of the SM-like Higgs boson. We additionally find that a strong EWPT requires an enhancement of the SM-like trilinear Higgs coupling at next-to-leading order (NLO) by up to a factor of 2.4 compared to the NLO SM coupling, establishing another link between cosmology and collider phenomenology. We provide several C2HDM benchmark scenarios compatible with a strong EWPT and all experimental and theoretical constraints. We include the dominant branching ratios of the non-SM-like Higgs bosons as well as the Higgs pair production cross section of the SM-like Higgs boson for every benchmark point. The pair production cross sections can be substantially enhanced compared to the SM and could be observable at the high-luminosity LHC, allowing access to the trilinear
Phase transition in finite systems
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph.; Duflot, V. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France); Duflot, V.; Gulminelli, F. [Laboratoire de Physique Corpusculaire, LPC-ISMRa, CNRS-IN2P3, 14 - Caen (France)
2000-07-01
The general problem of the definition of a phase transition without employing the thermodynamical limit is addressed. Different necessary conditions are considered and illustrated with examples from different nuclear and general physics phenomenologies. (authors)
Phase transition in finite systems
International Nuclear Information System (INIS)
Chomaz, Ph.; Duflot, V.; Duflot, V.; Gulminelli, F.
2000-01-01
The general problem of the definition of a phase transition without employing the thermodynamical limit is addressed. Different necessary conditions are considered and illustrated with examples from different nuclear and general physics phenomenologies. (authors)
Signatures of topological phase transitions in mesoscopic superconducting rings
International Nuclear Information System (INIS)
Pientka, Falko; Romito, Alessandro; Duckheim, Mathias; Oppen, Felix von; Oreg, Yuval
2013-01-01
We investigate Josephson currents in mesoscopic rings with a weak link which are in or near a topological superconducting phase. As a paradigmatic example, we consider the Kitaev model of a spinless p-wave superconductor in one dimension, emphasizing how this model emerges from more realistic settings based on semiconductor nanowires. We show that the flux periodicity of the Josephson current provides signatures of the topological phase transition and the emergence of Majorana fermions (MF) situated on both sides of the weak link even when fermion parity is not a good quantum number. In large rings, the MF hybridize only across the weak link. In this case, the Josephson current is h/e periodic in the flux threading the loop when fermion parity is a good quantum number but reverts to the more conventional h/2e periodicity in the presence of fermion-parity changing relaxation processes. In mesoscopic rings, the MF also hybridize through their overlap in the interior of the superconducting ring. We find that in the topological superconducting phase, this gives rise to an h/e-periodic contribution even when fermion parity is not conserved and that this contribution exhibits a peak near the topological phase transition. This signature of the topological phase transition is robust to the effects of disorder. As a byproduct, we find that close to the topological phase transition, disorder drives the system deeper into the topological phase. This is in stark contrast to the known behavior far from the phase transition, where disorder tends to suppress the topological phase. (paper)
Shear induced phase transitions induced in edible fats
Mazzanti, Gianfranco; Welch, Sarah E.; Marangoni, Alejandro G.; Sirota, Eric B.; Idziak, Stefan H. J.
2003-03-01
The food industry crystallizes fats under different conditions of temperature and shear to obtain products with desired crystalline phases. Milk fat, palm oil, cocoa butter and chocolate were crystallized from the melt in a temperature controlled Couette cell. Synchrotron x-ray diffraction studies were conducted to examine the role of shear on the phase transitions seen in edible fats. The shear forces on the crystals induced acceleration of the alpha to beta-prime phase transition with increasing shear rate in milk fat and palm oil. The increase was slow at low shear rates and became very strong above 360 s-1. In cocoa butter the acceleration between beta-prime-III and beta-V phase transition increased until a maximum of at 360 s-1, and then decreased, showing competition between enhanced heat transfer and viscous heat generation.
Structural phase transition in monolayer MoTe2 driven by electrostatic doping
Wang, Ying; Xiao, Jun; Zhu, Hanyu; Li, Yao; Alsaid, Yousif; Fong, King Yan; Zhou, Yao; Wang, Siqi; Shi, Wu; Wang, Yuan; Zettl, Alex; Reed, Evan J.; Zhang, Xiang
2017-10-01
Monolayers of transition-metal dichalcogenides (TMDs) exhibit numerous crystal phases with distinct structures, symmetries and physical properties. Exploring the physics of transitions between these different structural phases in two dimensions may provide a means of switching material properties, with implications for potential applications. Structural phase transitions in TMDs have so far been induced by thermal or chemical means; purely electrostatic control over crystal phases through electrostatic doping was recently proposed as a theoretical possibility, but has not yet been realized. Here we report the experimental demonstration of an electrostatic-doping-driven phase transition between the hexagonal and monoclinic phases of monolayer molybdenum ditelluride (MoTe2). We find that the phase transition shows a hysteretic loop in Raman spectra, and can be reversed by increasing or decreasing the gate voltage. We also combine second-harmonic generation spectroscopy with polarization-resolved Raman spectroscopy to show that the induced monoclinic phase preserves the crystal orientation of the original hexagonal phase. Moreover, this structural phase transition occurs simultaneously across the whole sample. This electrostatic-doping control of structural phase transition opens up new possibilities for developing phase-change devices based on atomically thin membranes.
Model for pairing phase transition in atomic nuclei
International Nuclear Information System (INIS)
Schiller, A.; Guttormsen, M.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.
2002-01-01
A model is developed which allows the investigation and classification of the pairing phase transition in atomic nuclei. The regions of the parameter space are discussed for which a pairing phase transition can be observed. The model parameters include number of particles, attenuation of pairing correlations with increasing seniority, single-particle level spacing, and pairing gap parameter
Experimental study of the lifetime and phase transition in neutron-rich Zr 98 ,100 ,102
Ansari, S.; Régis, J.-M.; Jolie, J.; Saed-Samii, N.; Warr, N.; Korten, W.; Zielińska, M.; Salsac, M.-D.; Blanc, A.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T.; Simpson, G. S.; Drouet, F.; Vancraeyenest, A.; de France, G.; Clément, E.; Stezowski, O.; Ur, C. A.; Urban, W.; Regan, P. H.; Podolyák, Zs.; Larijani, C.; Townsley, C.; Carroll, R.; Wilson, E.; Mach, H.; Fraile, L. M.; Paziy, V.; Olaizola, B.; Vedia, V.; Bruce, A. M.; Roberts, O. J.; Smith, J. F.; Scheck, M.; Kröll, T.; Hartig, A.-L.; Ignatov, A.; Ilieva, S.; Lalkovski, S.; Mǎrginean, N.; Otsuka, T.; Shimizu, N.; Togashi, T.; Tsunoda, Y.
2017-11-01
Rapid shape changes are observed for neutron-rich nuclei with A around 100. In particular, a sudden onset of ground-state deformation is observed in the Zr and Sr isotopic chains at N = 60: Low-lying states in N ≤58 nuclei are nearly spherical, while those with N ≥60 have a rotational character. Nuclear lifetimes as short as a few picoseconds can be measured using fast-timing techniques with LaBr3(Ce) scintillators, yielding a key ingredient in the systematic study of the shape evolution in this region. We used neutron-induced fission of 241Pu and 235U to study lifetimes of excited states in fission fragments in the A ˜100 region with the EXILL-FATIMA array located at the PF1B cold neutron beam line at the Institut Laue-Langevin. In particular, we applied the generalized centroid difference method to deduce lifetimes of low-lying states for the nuclei 98Zr (N = 58), 100Zr, and 102Zr (N ≥60 ). The results are discussed in the context of the presumed phase transition in the Zr chain by comparing the experimental transition strengths with the theoretical calculations using the interacting boson model and the Monte Carlo shell model.
Deconfinement phase transition in QCD with heavy quarks
International Nuclear Information System (INIS)
Attig, N.; Petersson, B.; Wolff, M.; Gavai, R.V.
1988-01-01
Using the pseudo-fermion method to simulate QCD with dynamical quarks we investigate the effects of heavy dynamical quarks of 2 flavours on the deconfinement phase transition in the quenched QCD. As the mass of the quark is decreased the phase transition weakens as expected. Compared to the earlier results with leading order hopping parameter expansion, however, the weakening is less rapid. Our estimated upper bound on the critical mass where the transition becomes continuous is 1.5-2 times lower than earlier results. (orig.)
Phase transition in a modified square Josephson-junction array
Han, J
1999-01-01
We study the phase transition in a modified square proximity-coupled Josephson-junction array with small superconducting islands at the center of each plaquette. We find that the modified square array undergoes a Kosterlitz-Thouless-Berezinskii-like phase transition, but at a lower temperature than the simple square array with the same single-junction critical current. The IV characteristics, as well as the phase transition, resemble qualitatively those of a disordered simple square array. The effects of the presence of the center islands in the modified square array are discussed.
DEFF Research Database (Denmark)
Reichardt, P; Nielsen, Ole Steen; Bauer, S
2007-01-01
No standard treatment is established for patients with advanced soft tissue sarcoma after previous chemotherapy with anthracyclines and ifosfamide, given either in combination or sequentially. Exatecan (DX-8951f) is a totally synthetic analogue of the topoisomerase I-inhibitor camptothecin, which...... was synthesised to impart increased aqueous solubility, greater tumour efficacy, and less toxicity than camptothecin itself, topotecan or irinotecan. Since some activity against soft tissue sarcomas, especially leiomyosarcomas, has been reported for topoisomerase I-inhibitors, a study with a new and more potent...... agent seemed justified. We report on a prospective multicentre phase II study of Exatecan in adult soft tissue sarcomas failing 1 or 2 lines of chemotherapy in advanced phase, performed within the STBSG of EORTC. Thirty-nine patients (16 leiomyosarcomas and 23 other histologies) were included in two...
Gravitationally self-induced phase transition
International Nuclear Information System (INIS)
Novello, M.; Duque, S.L.S.
1990-01-01
We propose a new mechanism by means of which a phase transition can be stimulated by self-gravitating matter. We suggest that this model could be used to explain the observed isotropy of the Universe. (orig.)
Quantum phase transitions between a class of symmetry protected topological states
Energy Technology Data Exchange (ETDEWEB)
Tsui, Lokman; Jiang, Hong-Chen; Lu, Yuan-Ming; Lee, Dung-Hai
2015-07-01
The subject of this paper is the phase transition between symmetry protected topological states (SPTs). We consider spatial dimension d and symmetry group G so that the cohomology group, Hd+1(G,U(1)), contains at least one Z2n or Z factor. We show that the phase transition between the trivial SPT and the root states that generate the Z2n or Z groups can be induced on the boundary of a (d+1)-dimensional View the MathML source-symmetric SPT by a View the MathML source symmetry breaking field. Moreover we show these boundary phase transitions can be “transplanted” to d dimensions and realized in lattice models as a function of a tuning parameter. The price one pays is for the critical value of the tuning parameter there is an extra non-local (duality-like) symmetry. In the case where the phase transition is continuous, our theory predicts the presence of unusual (sometimes fractionalized) excitations corresponding to delocalized boundary excitations of the non-trivial SPT on one side of the transition. This theory also predicts other phase transition scenarios including first order transition and transition via an intermediate symmetry breaking phase.
Multi-Phase Sub-Sampling Fractional-N PLL with soft loop switching for fast robust locking
Liao, Dongyi; Dai, FA Foster; Nauta, Bram; Klumperink, Eric A.M.
2017-01-01
This paper presents a low phase noise sub-sampling PLL (SSPLL) with multi-phase outputs. Automatic soft switching between the sub-sampling phase loop and frequency loop is proposed to improve robustness against perturbations and interferences that may cause a traditional SSPLL to lose lock. A
Superconducting phase transition in STM tips
Energy Technology Data Exchange (ETDEWEB)
Eltschka, Matthias; Jaeck, Berthold; Assig, Maximilian; Etzkorn, Markus; Ast, Christian R. [Max Planck Institute for Solid State Research, Stuttgart (Germany); Kern, Klaus [Max Planck Institute for Solid State Research, Stuttgart (Germany); Ecole Polytechnique Federale de Lausanne (Switzerland)
2015-07-01
The superconducting properties of systems with dimensions comparable to the London penetration depth considerably differ from macroscopic systems. We have studied the superconducting phase transition of vanadium STM tips in external magnetic fields. Employing Maki's theory we extract the superconducting parameters such as the gap or the Zeeman splitting from differential conductance spectra. While the Zeeman splitting follows the theoretical description of a system with s=1/2 and g=2, the superconducting gaps as well as the critical fields depend on the specific tip. For a better understanding of the experimental results, we solve a one dimensional Usadel equation modeling the superconducting tip as a cone with the opening angle α in an external magnetic field. We find that only a small region at the apex of the tip is superconducting in high magnetic fields and that the order of the phase transition is directly determined by α. Further, the spectral broadening increases with α indicating an intrinsic broadening mechanism due to the conical shape of the tip. Comparing these calculations to our experimental results reveals the order of the superconducting phase transition of the STM tips.
Wainwright, Carroll L.
2012-09-01
I present a numerical package (CosmoTransitions) for analyzing finite-temperature cosmological phase transitions driven by single or multiple scalar fields. The package analyzes the different vacua of a theory to determine their critical temperatures (where the vacuum energy levels are degenerate), their supercooling temperatures, and the bubble wall profiles which separate the phases and describe their tunneling dynamics. I introduce a new method of path deformation to find the profiles of both thin- and thick-walled bubbles. CosmoTransitions is freely available for public use.Program summaryProgram Title: CosmoTransitionsCatalogue identifier: AEML_v1_0Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEML_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 8775No. of bytes in distributed program, including test data, etc.: 621096Distribution format: tar.gzProgramming language: Python.Computer: Developed on a 2009 MacBook Pro. No computer-specific optimization was performed.Operating system: Designed and tested on Mac OS X 10.6.8. Compatible with any OS with Python installed.RAM: Approximately 50 MB, mostly for loading plotting packages.Classification: 1.9, 11.1.External routines: SciPy, NumPy, matplotLibNature of problem: I describe a program to analyze early-Universe finite-temperature phase transitions with multiple scalar fields. The goal is to analyze the phase structure of an input theory, determine the amount of supercooling at each phase transition, and find the bubble-wall profiles of the nucleated bubbles that drive the transitions.Solution method: To find the bubble-wall profile, the program assumes that tunneling happens along a fixed path in field space. This reduces the equations of motion to one dimension, which can then be solved using the overshoot
Explosive transitions to synchronization in networks of phase oscillators.
Leyva, I; Navas, A; Sendiña-Nadal, I; Almendral, J A; Buldú, J M; Zanin, M; Papo, D; Boccaletti, S
2013-01-01
The emergence of dynamical abrupt transitions in the macroscopic state of a system is currently a subject of the utmost interest. The occurrence of a first-order phase transition to synchronization of an ensemble of networked phase oscillators was reported, so far, for very particular network architectures. Here, we show how a sharp, discontinuous transition can occur, instead, as a generic feature of networks of phase oscillators. Precisely, we set conditions for the transition from unsynchronized to synchronized states to be first-order, and demonstrate how these conditions can be attained in a very wide spectrum of situations. We then show how the occurrence of such transitions is always accompanied by the spontaneous setting of frequency-degree correlation features. Third, we show that the conditions for abrupt transitions can be even softened in several cases. Finally, we discuss, as a possible application, the use of this phenomenon to express magnetic-like states of synchronization.
High-pressure phase transition and phase diagram of gallium arsenide
Besson, J. M.; Itié, J. P.; Polian, A.; Weill, G.; Mansot, J. L.; Gonzalez, J.
1991-09-01
Under hydrostatic pressure, cubic GaAs-I undergoes phase transitions to at least two orthorhombic structures. The initial phase transition to GaAs-II has been investigated by optical-transmittance measurements, Raman scattering, and x-ray absorption. The structure of pressurized samples, which are retrieved at ambient, has been studied by x-ray diffraction and high-resolution diffraction microscopy. Various criteria that define the domain of stability of GaAs-I are examined, such as the occurrence of crystalline defects, the local variation in atomic coordination number, or the actual change in crystal structure. These are shown not to occur at the same pressure at 300 K, the latter being observable only several GPa above the actual thermodynamic instability pressure of GaAs-I. Comparison of the evolution of these parameters on increasing and decreasing pressure locates the thermodynamic transition region GaAs-I-->GaAs-II at 12+/-1.5 GPa and at 300 K that is lower than generally reported. The use of thermodynamic relations around the triple point, and of regularities in the properties of isoelectronic and isostructural III-V compounds, yields a phase diagram for GaAs which is consistent with this value.
Van der Waals phase transition in the framework of holography
International Nuclear Information System (INIS)
Zeng, Xiao-Xiong; Li, Li-Fang
2017-01-01
Phase structure of the quintessence Reissner–Nordström–AdS black hole is probed by the nonlocal observables such as holographic entanglement entropy and two point correlation function. Our result shows that, as the case of the thermal entropy, both the observables exhibit the Van der Waals-like phase transition. To reinforce this conclusion, we further check the equal area law for the first order phase transition and critical exponent of the heat capacity for the second order phase transition. We also discuss the effect of the state parameter on the phase structure of the nonlocal observables.
Van der Waals phase transition in the framework of holography
Energy Technology Data Exchange (ETDEWEB)
Zeng, Xiao-Xiong, E-mail: xxzeng@itp.ac.cn [State School of Material Science and Engineering, Chongqing Jiaotong University, Chongqing 400074 (China); Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); Li, Li-Fang, E-mail: lilf@itp.ac.cn [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China)
2017-01-10
Phase structure of the quintessence Reissner–Nordström–AdS black hole is probed by the nonlocal observables such as holographic entanglement entropy and two point correlation function. Our result shows that, as the case of the thermal entropy, both the observables exhibit the Van der Waals-like phase transition. To reinforce this conclusion, we further check the equal area law for the first order phase transition and critical exponent of the heat capacity for the second order phase transition. We also discuss the effect of the state parameter on the phase structure of the nonlocal observables.
Van der Waals phase transition in the framework of holography
Directory of Open Access Journals (Sweden)
Xiao-Xiong Zeng
2017-01-01
Full Text Available Phase structure of the quintessence Reissner–Nordström–AdS black hole is probed by the nonlocal observables such as holographic entanglement entropy and two point correlation function. Our result shows that, as the case of the thermal entropy, both the observables exhibit the Van der Waals-like phase transition. To reinforce this conclusion, we further check the equal area law for the first order phase transition and critical exponent of the heat capacity for the second order phase transition. We also discuss the effect of the state parameter on the phase structure of the nonlocal observables.
Measurements of Vector Boson Fusion with the ATLAS detector
Calfayan, Philippe; The ATLAS collaboration
2018-01-01
The most recent results on the production of single W and Z bosons with two jets at high invariant mass at centre-of-mass energies of 7, 8 and 13 TeV are presented. Integrated and differential cross sections are measured in many different phase space regions with varying degree of sensitivity to the electroweak production in vector boson fusion. The cross section for the electroweak W boson production has been extracted for both integrated and for the first time differential distributions. The results are compared to state-of-the-art theory predictions and are used to constrain anomalous gauge couplings.
Moessbauer study of phase transitions under high hydrostatic pressures. 1
International Nuclear Information System (INIS)
Kapitanov, E.V.; Yakovlev, E.N.
1979-01-01
Experimental results of the hydrostatic pressure influence on Moessbauer spectrum parameters are obtained over the pressure range including the area of structural phase transition. A linear increase of the Moessbauer effect probability (recoilless fraction) is accompanied by a linear decrease of the electron density at tin nuclei within the pressure range foregoing the phase transition. The electric resistance and the recoilless fraction of the new phase of Mg 2 Sn are lower, but the electron density at tin nuclei is greater than the initial phase ones. Hydrostatic conditions allow to fix clearly the diphasic transition area and to determine the influence of the pressure on the Moessbauer line position and on the recoilless fraction of the high pressure phase. The phase transition heat Q = 415 cal mol -1 is calculated using recoilless fractions of the high and low pressure phases at 25 kbar. The present results are qualitatively and quantitatively different from the results, obtained at nonhydrostatic conditions. (author)
Photoinduced charge transfer phase transition in cesium manganese hexacyanoferrate
International Nuclear Information System (INIS)
Matsuda, Tomoyuki; Tokoro, Hiroko; Hashimoto, Kazuhito; Ohkoshi, Shin-ichi
2007-01-01
Cesium manganese hexacyanoferrate, Cs 1.51 Mn[Fe(CN) 6 ], shows a thermal phase transition between Mn II -NC-Fe III [high-temperature (HT) phase] and Mn III -NC-Fe II [low-temperature (LT) phase] with phase transition temperatures of 170 K (HT→LT) and 230 K (LT→HT). The LT phase shows ferromagnetism with Curie temperature of 7 K and coercive field of 60 Oe. Irradiating with 532 nm laser light converts the LT phase into the photoinduced (PI) phase, which does not have spontaneous magnetization. The electronic state of the PI phase corresponds to that of the HT phase and the relaxation temperature from the PI to the LT phase is observed at 90 K
Role of relativity in high-pressure phase transitions of thallium.
Kotmool, Komsilp; Chakraborty, Sudip; Bovornratanaraks, Thiti; Ahuja, Rajeev
2017-02-20
We demonstrate the relativistic effects in high-pressure phase transitions of heavy element thallium. The known first phase transition from h.c.p. to f.c.c. is initially investigated by various relativistic levels and exchange-correlation functionals as implemented in FPLO method, as well as scalar relativistic scheme within PAW formalism. The electronic structure calculations are interpreted from the perspective of energetic stability and electronic density of states. The full relativistic scheme (FR) within L(S)DA performs to be the scheme that resembles mostly with experimental results with a transition pressure of 3 GPa. The s-p hybridization and the valence-core overlapping of 6s and 5d states are the primary reasons behind the f.c.c. phase occurrence. A recent proposed phase, i.e., a body-centered tetragonal (b.c.t.) phase, is confirmed with a small distortion from the f.c.c. phase. We have also predicted a reversible b.c.t. → f.c.c. phase transition at 800 GPa. This finding has been suggested that almost all the III-A elements (Ga, In and Tl) exhibit the b.c.t. → f.c.c. phase transition at extremely high pressure.
Signatures of a dissipative phase transition in photon correlation measurements
Fink, Thomas; Schade, Anne; Höfling, Sven; Schneider, Christian; Imamoglu, Ataç
2018-04-01
Understanding and characterizing phase transitions in driven-dissipative systems constitutes a new frontier for many-body physics1-8. A generic feature of dissipative phase transitions is a vanishing gap in the Liouvillian spectrum9, which leads to long-lived deviations from the steady state as the system is driven towards the transition. Here, we show that photon correlation measurements can be used to characterize the corresponding critical slowing down of non-equilibrium dynamics. We focus on the extensively studied phenomenon of optical bistability in GaAs cavity polaritons10,11, which can be described as a first-order dissipative phase transition12-14. Increasing the excitation strength towards the bistable range results in an increasing photon-bunching signal along with a decay time that is prolonged by more than nine orders of magnitude as compared with that of single polaritons. In the limit of strong polariton interactions leading to pronounced quantum fluctuations, the mean-field bistability threshold is washed out. Nevertheless, the functional form with which the Liouvillian gap closes as the thermodynamic limit is approached provides a signature of the emerging dissipative phase transition. Our results establish photon correlation measurements as an invaluable tool for studying dynamical properties of dissipative phase transitions without requiring phase-sensitive interferometric measurements.
Pressure-induced phase transitions in nanocrystalline ReO3
International Nuclear Information System (INIS)
Biswas, Kanishka; Muthu, D V S; Sood, A K; Kruger, M B; Chen, B; Rao, C N R
2007-01-01
Pressure-induced phase transitions in the nanocrystals of ReO 3 with an average diameter of ∼12 nm have been investigated in detail by using synchrotron x-ray diffraction and the results compared with the literature data of bulk samples of ReO 3 . The study shows that the ambient-pressure cubic I phase (space group Pm3-barm) transforms to a monoclinic phase (space group C 2/c), then to a rhombohedral I phase (space group R3-barc), and finally to another rhombohedral phase (rhombohedral II, space group R3-barc) with increasing pressure over the 0.0-20.3 GPa range. The cubic I to monoclinic transition is associated with the largest volume change (∼5%), indicative of a reconstructive transition. The transition pressures are generally lower than those known for bulk ReO 3 . The cubic II (Im3-bar) or tetragonal (P4/mbm) phases do not occur at lower pressures. The nanocrystals are found to be more compressible than bulk ReO 3 . On decompression to ambient pressure, the structure does not revert back to the cubic I structure
A stress-induced phase transition model for semi-crystallize shape memory polymer
Guo, Xiaogang; Zhou, Bo; Liu, Liwu; Liu, Yanju; Leng, Jinsong
2014-03-01
The developments of constitutive models for shape memory polymer (SMP) have been motivated by its increasing applications. During cooling or heating process, the phase transition which is a continuous time-dependent process happens in semi-crystallize SMP and the various individual phases form at different temperature and in different configuration. Then, the transformation between these phases occurred and shape memory effect will emerge. In addition, stress applied on SMP is an important factor for crystal melting during phase transition. In this theory, an ideal phase transition model considering stress or pre-strain is the key to describe the behaviors of shape memory effect. So a normal distributed model was established in this research to characterize the volume fraction of each phase in SMP during phase transition. Generally, the experiment results are partly backward (in heating process) or forward (in cooling process) compared with the ideal situation considering delay effect during phase transition. So, a correction on the normal distributed model is needed. Furthermore, a nonlinear relationship between stress and phase transition temperature Tg is also taken into account for establishing an accurately normal distributed phase transition model. Finally, the constitutive model which taking the stress as an influence factor on phase transition was also established. Compared with the other expressions, this new-type model possesses less parameter and is more accurate. For the sake of verifying the rationality and accuracy of new phase transition and constitutive model, the comparisons between the simulated and experimental results were carried out.
Cartier dit Moulin, Ch.; Flank, A.M.; Rudolf, P.; Chen, C.T.
1993-01-01
Soft X-ray Absorption Spectroscopy at the transition metal L2,3 edges provides information about the 3d unoccupied states by dipole allowed transitions. We have recorded iron L2,3 edges in order to follow the reversible thermal spin interconversion (S=2 S=0) of the Fe(II)(o-phenantroline)2(NCS)2.
Phase transitions in nuclear matter
International Nuclear Information System (INIS)
Glendenning, N.K.
1984-11-01
The rather general circumstances under which a phase transition in hadronic matter at finite temperature to an abnormal phase in which baryon effective masses become small and in which copious baryon-antibaryon pairs appear is emphasized. A preview is also given of a soliton model of dense matter, in which at a density of about seven times nuclear density, matter ceases to be a color insulator and becomes increasingly color conducting. 22 references
Phase transitions and quantum entropy
International Nuclear Information System (INIS)
Arrachea, L.; Canosa, N.; Plastino, A.; Portesi, M.; Rossignoli, R.
1990-01-01
An examination is made of the possibility to predict phase transitions of the fundamental state of finite quantum system, knowing the quantum entropy of these states, defined on the basis of the information theory. (Author). 7 refs., 3 figs
An objective indicator for two-phase flow pattern transition
International Nuclear Information System (INIS)
Hervieu, E.; Seleghim, P. Jr.
1998-01-01
This work concerns the development of a methodology which objective is to characterize and diagnose two-phase flow regime transitions. The approach is based on the fundamental assumption that a transition flow is less stationary than a flow with an established regime. In a first time, the efforts focused on: the design and construction of an experimental loop, allowing to reproduce the main horizontal two-phase flow patterns, in a stable and controlled way; the design and construction of an electrical impedance probe, providing an imaged information of the spatial phase distribution in the pipe; the systematic study of the joint time-frequency and time-scale analysis methods, which permitted to define an adequate parameter quantifying the unstationarity degree. In a second time, in order to verify the fundamental assumption, a series of experiments were conducted, which objective was to demonstrate the correlation between unstationarity and regime transition. The unstationarity degree was quantified by calculating the Gabor's transform time-frequency covariance of the impedance probe signals. Furthermore, the phenomenology of each transition was characterized by the joint moments and entropy. The results clearly show that the regime transitions are correlated with local time-frequency covariance peaks, which demonstrates that these regime transitions are characterized by a loss of stationarity. Consequently, the time-frequency covariance constitutes an objective two-phase flow regime transition indicator. (author)
Multiple phase transitions in the generalized Curie-Weiss model
International Nuclear Information System (INIS)
Eisele, T.; Ellis, R.S.
1988-01-01
The generalized Curie-Weiss model is an extension of the classical Curie-Weiss model in which the quadratic interaction function of the mean spin value is replaced by a more general interaction function. It is shown that the generalized Curie-Weiss model can have a sequence of phase transitions at different critical temperatures. Both first-order and second-order phase transitions can occur, and explicit criteria for the two types are given. Three examples of generalized Curie-Weiss models are worked out in detail, including one example with infinitely many phase transitions. A number of results are derived using large-deviation techniques
Phase transitions in Pareto optimal complex networks.
Seoane, Luís F; Solé, Ricard
2015-09-01
The organization of interactions in complex systems can be described by networks connecting different units. These graphs are useful representations of the local and global complexity of the underlying systems. The origin of their topological structure can be diverse, resulting from different mechanisms including multiplicative processes and optimization. In spatial networks or in graphs where cost constraints are at work, as it occurs in a plethora of situations from power grids to the wiring of neurons in the brain, optimization plays an important part in shaping their organization. In this paper we study network designs resulting from a Pareto optimization process, where different simultaneous constraints are the targets of selection. We analyze three variations on a problem, finding phase transitions of different kinds. Distinct phases are associated with different arrangements of the connections, but the need of drastic topological changes does not determine the presence or the nature of the phase transitions encountered. Instead, the functions under optimization do play a determinant role. This reinforces the view that phase transitions do not arise from intrinsic properties of a system alone, but from the interplay of that system with its external constraints.
Energy Technology Data Exchange (ETDEWEB)
Hauke, Philipp [ICFO-Institut de Ciencies Fotoniques, Meditarranean Technology Park, E-08860 Castelldefels, Barcelona (Spain); Roscilde, Tommaso [Laboratoire de Physique, Ecole Normale Superieure de Lyon, 46 Allee d' Italie, F-69007 Lyon (France); Murg, Valentin; Ignacio Cirac, J; Schmied, Roman, E-mail: Philipp.Hauke@icfo.e [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany)
2010-05-15
We investigate a system of frustrated hardcore bosons, modeled by an XY antiferromagnet on the spatially anisotropic triangular lattice, using Takahashi's modified spin-wave (MSW) theory. In particular, we implement ordering vector optimization on the ordered reference state of MSW theory, which leads to significant improvement of the theory and accounts for quantum corrections to the classically ordered state. The MSW results at zero temperature compare favorably to exact diagonalization (ED) and projected entangled-pair state (PEPS) calculations. The resulting zero-temperature phase diagram includes a one-dimensional (1D) quasi-ordered phase, a 2D Neel ordered phase and a 2D spiraling ordered phase. Strong indications coming from the ED and PEPS calculations, as well as from the breakdown of MSW theory, suggest that the various ordered or quasi-ordered phases are separated by spin-liquid phases with short-range correlations, in analogy to what has been predicted for the Heisenberg model on the same lattice. Within MSW theory, we also explore the finite-temperature phase diagram. In agreement with the Berezinskii-Kosterlitz-Thouless (BKT) theory, we find that zero-temperature long-range-ordered phases turn into quasi-ordered phases (up to a BKT transition temperature), while zero-temperature quasi-ordered phases become short-range correlated at finite temperature. These results show that, despite its simplicity, MSW theory is very well suited to describing ordered and quasi-ordered phases of frustrated XY spins (or, equivalently, of frustrated lattice bosons) both at zero and finite temperatures. While MSW theory, just as other theoretical methods, cannot describe spin-liquid phases, its breakdown provides a fast and reliable method for singling out Hamiltonians that may feature these intriguing quantum phases. We thus suggest a tool for guiding our search for interesting systems whose properties are necessarily studied with a physical quantum simulator
Geometry-induced phase transition in fluids: capillary prewetting.
Yatsyshin, Petr; Savva, Nikos; Kalliadasis, Serafim
2013-02-01
We report a new first-order phase transition preceding capillary condensation and corresponding to the discontinuous formation of a curved liquid meniscus. Using a mean-field microscopic approach based on the density functional theory we compute the complete phase diagram of a prototypical two-dimensional system exhibiting capillary condensation, namely that of a fluid with long-ranged dispersion intermolecular forces which is spatially confined by a substrate forming a semi-infinite rectangular pore exerting long-ranged dispersion forces on the fluid. In the T-μ plane the phase line of the new transition is tangential to the capillary condensation line at the capillary wetting temperature T(cw). The surface phase behavior of the system maps to planar wetting with the phase line of the new transition, termed capillary prewetting, mapping to the planar prewetting line. If capillary condensation is approached isothermally with T>T(cw), the meniscus forms at the capping wall and unbinds continuously, making capillary condensation a second-order phenomenon. We compute the corresponding critical exponent for the divergence of adsorption.
Polymorphic phase transitions: Macroscopic theory and molecular simulation.
Anwar, Jamshed; Zahn, Dirk
2017-08-01
Transformations in the solid state are of considerable interest, both for fundamental reasons and because they underpin important technological applications. The interest spans a wide spectrum of disciplines and application domains. For pharmaceuticals, a common issue is unexpected polymorphic transformation of the drug or excipient during processing or on storage, which can result in product failure. A more ambitious goal is that of exploiting the advantages of metastable polymorphs (e.g. higher solubility and dissolution rate) while ensuring their stability with respect to solid state transformation. To address these issues and to advance technology, there is an urgent need for significant insights that can only come from a detailed molecular level understanding of the involved processes. Whilst experimental approaches at best yield time- and space-averaged structural information, molecular simulation offers unprecedented, time-resolved molecular-level resolution of the processes taking place. This review aims to provide a comprehensive and critical account of state-of-the-art methods for modelling polymorph stability and transitions between solid phases. This is flanked by revisiting the associated macroscopic theoretical framework for phase transitions, including their classification, proposed molecular mechanisms, and kinetics. The simulation methods are presented in tutorial form, focusing on their application to phase transition phenomena. We describe molecular simulation studies for crystal structure prediction and polymorph screening, phase coexistence and phase diagrams, simulations of crystal-crystal transitions of various types (displacive/martensitic, reconstructive and diffusive), effects of defects, and phase stability and transitions at the nanoscale. Our selection of literature is intended to illustrate significant insights, concepts and understanding, as well as the current scope of using molecular simulations for understanding polymorphic
Extracellular ice phase transitions in insects.
Hawes, T C
2014-01-01
At temperatures below their temperature of crystallization (Tc), the extracellular body fluids of insects undergo a phase transition from liquid to solid. Insects that survive the transition to equilibrium (complete freezing of the body fluids) are designated as freeze tolerant. Although this phenomenon has been reported and described in many Insecta, current nomenclature and theory does not clearly delineate between the process of transition (freezing) and the final solid phase itself (the frozen state). Thus freeze tolerant insects are currently, by convention, described in terms of the temperature at which the crystallization of their body fluids is initiated, Tc. In fact, the correct descriptor for insects that tolerate freezing is the temperature of equilibrium freezing, Tef. The process of freezing is itself a separate physical event with unique physiological stresses that are associated with ice growth. Correspondingly there are a number of insects whose physiological cryo-limits are very specifically delineated by this transitional envelope. The distinction also has considerable significance for our understanding of insect cryobiology: firstly, because the ability to manage endogenous ice growth is a fundamental segregator of cryotype; and secondly, because our understanding of internal ice management is still largely nascent.
The geometric content of the interacting boson model for molecular spectra
International Nuclear Information System (INIS)
Levit, S.; Smilansky, U.
1981-12-01
The recently proposed algebraic model for collective spectra of diatomic molecules is analysed in terms of conventional geometrical degrees of freedom. We present a mapping of the algebraic Hamiltonian onto an exactly solvable geometrical Hamiltonian with the Morse potential. This mapping explains the success of the algebraic model in reproducing the low lying part of molecular spectra. At the same time the mapping shows that the expression for the dipole transition operator in terms of boson operators differs from the simplest IBM expression and in general must include many-body boson terms. The study also provides an insight into the problem of possible interpretations of the bosons in the nuclear IBM. (author)
Holography and the Electroweak Phase Transition
Creminelli, Paolo; Rattazzi, Riccardo; Creminelli, Paolo; Nicolis, Alberto; Rattazzi, Riccardo
2002-01-01
We study through holography the compact Randall-Sundrum (RS) model at finite temperature. In the presence of radius stabilization, the system is described at low enough temperature by the RS solution. At high temperature it is described by the AdS-Schwarzshild solution with an event horizon replacing the TeV brane. We calculate the transition temperature T_c between the two phases and we find it to be somewhat smaller than the TeV scale. Assuming that the Universe starts out at T >> T_c and cools down by expansion, we study the rate of the transition to the RS phase. We find that the transition is too slow and the Universe ends up in an old inflation scenario unless tight bounds are satisfied by the model parameters. In particular we find that the AdS curvature must be comparable to the 5D Planck mass and that the radius stabilization mechanism must lead to a sizeable distortion of the basic RS metric.
No Hawking-Page phase transition in three dimensions
International Nuclear Information System (INIS)
Myung, Y.S.
2005-01-01
We investigate whether or not the Hawking-Page phase transition is possible to occur in three dimensions. Starting with the simplest class of Lanczos-Lovelock action, thermodynamic behavior of all AdS-type black holes without charge falls into two classes: Schwarzschild-AdS black holes in even dimensions and Chern-Simons black holes in odd dimensions. The former class can provide the Hawking-Page transition between Schwarzschild-AdS black holes and thermal AdS space. On the other hand, the latter class is exceptional and thus the Hawking-Page transition is hard to occur. In three dimensions, a second-order phase transition might occur between the non-rotating BTZ black hole and the massless BTZ black hole (thermal AdS space), instead of the first-order Hawking-Page transition between the non-rotating BTZ black hole and thermal AdS space
Dynamical phase transitions in quantum mechanics
International Nuclear Information System (INIS)
Rotter, Ingrid
2012-01-01
1936 Niels Bohr: In the atom and in the nucleus we have indeed to do with two extreme cases of mechanical many-body problems for which a procedure of approximation resting on a combination of one-body problems, so effective in the former case, loses any validity in the latter where we, from the very beginning, have to do with essential collective aspects of the interplay between the constituent particles. 1963: Maria Goeppert-Mayer and J. Hans D. Jensen received the Nobel Prize in Physics for their discoveries concerning nuclear shell structure. State of the art 2011: - The nucleus is an open quantum system described by a non-Hermitian Hamilton operator with complex eigenvalues. The eigenvalues may cross in the complex plane ('exceptional points'), the phases of the eigenfunctions are not rigid in approaching the crossing points and the widths bifurcate. By this, a dynamical phase transition occurs in the many-level system. The dynamical phase transition starts at a critical value of the level density. Hence the properties of he low-lying nuclear states (described well by the shell model) and those of highly excited nuclear states (described by random ensembles) differ fundamentally from one another. The statement of Niels Bohr for compound nucleus states at high level density is not in contradiction to the shell-model description of nuclear (and atomic) states at low level density. Dynamical phase transitions are observed experimentally in different systems, including PT-symmetric ones, by varying one or more parameters
The Kibble-Zurek mechanism in phase transitions of non-equilibrium systems
Cheung, Hil F. H.; Patil, Yogesh S.; Date, Aditya G.; Vengalattore, Mukund
2017-04-01
We experimentally realize a driven-dissipative phase transition using a mechanical parametric amplifier to demonstrate key signatures of a second order phase transition, including a point where the susceptibilities and relaxation time scales diverge, and where the system exhibits a spontaneous breaking of symmetry. Though reminiscent of conventional equilibrium phase transitions, it is unclear if such driven-dissipative phase transitions are amenable to the conventional Landau-Ginsburg-Wilson paradigm, which relies on concepts of scale invariance and universality, and recent work has shown that such phase transitions can indeed lie beyond such conventional universality classes. By quenching the system past the critical point, we investigate the dynamics of the emergent ordered phase and find that our measurements are in excellent agreement with the Kibble-Zurek mechanism. In addition to verifying the Kibble-Zurek hypothesis in driven-dissipative phase transitions for the first time, we also demonstrate that the measured critical exponents accurately reflect the interplay between intrinsic coherent dynamics and environmental correlations, showing a clear departure from mean field exponents in the case of non-Markovian system-bath interactions. We further discuss how reservoir engineering and the imposition of artificial environmental correlations can result in the stabilization of novel many-body quantum phases and aid in the creation of exotic non-equilibrium states of matter.
International Nuclear Information System (INIS)
Pan'ko, G.F.; Prisedskij, V.V.; Klimov, V.V.
1983-01-01
Anisotropic diffusional scattering of electrons on PbZrO 3 crystal in the temperature range of phase transition has been recorded. As a result of its analysis it has been established that in lead zirconate the rotational vibrational mode G 25 plays the role of soft mode. The experiment is carried out using PbZrO 3 monocrystals in translucent electron microscope EhM-200, operating in the regime of microdiffraction at accelerating voltage of 150 kV and beam current 50 μA; sample preparation is realized using the method of shearing and fragmentation
Structural phase transitions in niobium oxide nanocrystals
Yuvakkumar, R.; Hong, Sun Ig
2015-09-01
Niobium oxide nanocrystals were successfully synthesized employing the green synthesis method. Phase formation, microstructure and compositional properties of 1, 4 and 7 days incubation treated samples after calcinations at 450 °C were examined using X-ray diffraction, Raman, photoluminescence (PL), infrared, X-ray photoelectron spectra and transmission electron microscopic characterizations. It was observed that phase formation of Nb2O5 nanocrystals was dependent upon the incubation period required to form stable metal oxides. The characteristic results clearly revealed that with increasing incubation and aging, the transformation of cubic, orthorhombic and monoclinic phases were observed. The uniform heating at room temperature (32 °C) and the ligation of niobium atoms due to higher phenolic constituents of utilized rambutan during aging processing plays a vital role in structural phase transitions in niobium oxide nanocrystals. The defects over a period of incubation and the intensities of the PL spectra changing over a period of aging were related to the amount of the defects induced by the phase transition.
Phase transitions in multiplicative competitive processes
International Nuclear Information System (INIS)
Shimazaki, Hideaki; Niebur, Ernst
2005-01-01
We introduce a discrete multiplicative process as a generic model of competition. Players with different abilities successively join the game and compete for finite resources. Emergence of dominant players and evolutionary development occur as a phase transition. The competitive dynamics underlying this transition is understood from a formal analogy to statistical mechanics. The theory is applicable to bacterial competition, predicting novel population dynamics near criticality
Interacting boson model: Microscopic calculations for the mercury isotopes
Energy Technology Data Exchange (ETDEWEB)
Druce, C.H.; Pittel, S.; Barrett, B.R.; Duval, P.D.
1987-05-15
Microscopic calculations of the parameters of the proton--neutron interacting boson model (IBM-2) appropriate to the even Hg isotopes are reported. The calculations are based on the Otsuka--Arima--Iachello boson mapping procedure, which is briefly reviewed. Renormalization of the parameters due to exclusion of the l = 4 g boson is treated perturbatively. The calculations employ a semi-realistic shell-model Hamiltonian with no adjustable parameters. The calculated parameters of the IBM-2 Hamiltonian are used to generate energy spectra and electromagnetic transition probabilities, which are compared with experimental data and with the result of phenomenological fits. The overall agreement is reasonable with some notable exceptions, which are discussed. Particular attention is focused on the parameters of the Majorana interaction and on the F-spin character of low-lying levels. copyright 1987 Academic Press, Inc.
Transverse momentum distributions of W and Z bosons produced in p anti p collisions at √ S = 1.8 TeV
International Nuclear Information System (INIS)
Abbott, B.
1997-10-01
The transverse momentum distributions of W and Z bosons produced in p anti p collisions at √s = 1.8 TeV are measured with the D0 detector at Fermilab. The results are compared to QCD calculations which include soft gluon resummation. The transverse momentum distribution of the Z boson is consistent with the calculation of Ladinsky and Yuan, and is used to extract their non-perturbative parameter 92-
Probing phase transitions via energetic nuclear collisions
International Nuclear Information System (INIS)
Lukacs, B.; Csernai, L.P.
1983-07-01
The possible effects of the nucleon-quark phase transition on the dynamics of heavy ion collisions are discussed. It is shown that the formation of the quark phase can be expected at recent experiments. Nevertheless, the compressibility of the two-phase mixture remains relatively low, thus the quark phase remains limited in both space and time, and the observables are not strongly affected. (author)
High pressure structural phase transitions of TiO2 nanomaterials
International Nuclear Information System (INIS)
Li Quan-Jun; Liu Bing-Bing
2016-01-01
Recently, the high pressure study on the TiO 2 nanomaterials has attracted considerable attention due to the typical crystal structure and the fascinating properties of TiO 2 with nanoscale sizes. In this paper, we briefly review the recent progress in the high pressure phase transitions of TiO 2 nanomaterials. We discuss the size effects and morphology effects on the high pressure phase transitions of TiO 2 nanomaterials with different particle sizes, morphologies, and microstructures. Several typical pressure-induced structural phase transitions in TiO 2 nanomaterials are presented, including size-dependent phase transition selectivity in nanoparticles, morphology-tuned phase transition in nanowires, nanosheets, and nanoporous materials, and pressure-induced amorphization (PIA) and polyamorphism in ultrafine nanoparticles and TiO 2 -B nanoribbons. Various TiO 2 nanostructural materials with high pressure structures are prepared successfully by high pressure treatment of the corresponding crystal nanomaterials, such as amorphous TiO 2 nanoribbons, α -PbO 2 -type TiO 2 nanowires, nanosheets, and nanoporous materials. These studies suggest that the high pressure phase transitions of TiO 2 nanomaterials depend on the nanosize, morphology, interface energy, and microstructure. The diversity of high pressure behaviors of TiO 2 nanomaterials provides a new insight into the properties of nanomaterials, and paves a way for preparing new nanomaterials with novel high pressure structures and properties for various applications. (topical review)
Energy Technology Data Exchange (ETDEWEB)
Shiozaki, Ken [Department of Physics, University of Illinois at Urbana Champaign,1110 West Green Street, Urbana, IL 61801 (United States); Ryu, Shinsei [James Franck Institute and Kadanoff Center for Theoretical Physics, University of Chicago,5640 South Ellis Ave, Chicago, IL 60637 (United States)
2017-04-18
Matrix Product States (MPSs) provide a powerful framework to study and classify gapped quantum phases — symmetry-protected topological (SPT) phases in particular — defined in one dimensional lattices. On the other hand, it is natural to expect that gapped quantum phases in the limit of zero correlation length are described by topological quantum field theories (TFTs or TQFTs). In this paper, for (1+1)-dimensional bosonic SPT phases protected by symmetry G, we bridge their descriptions in terms of MPSs, and those in terms of G-equivariant TFTs. In particular, for various topological invariants (SPT invariants) constructed previously using MPSs, we provide derivations from the point of view of (1+1) TFTs. We also discuss the connection between boundary degrees of freedom, which appear when one introduces a physical boundary in SPT phases, and “open” TFTs, which are TFTs defined on spacetimes with boundaries.
International Nuclear Information System (INIS)
Wasilewski, W.
1983-08-01
This paper presents a theoretical description of the phase transition from a paramagnetic phase P to the homogeneous and domain structure ferromagnetic phases within the phenomenological theory of phase transitions
Isotropic–Nematic Phase Transitions in Gravitational Systems
Energy Technology Data Exchange (ETDEWEB)
Roupas, Zacharias; Kocsis, Bence [Institute of Physics, Eötvös University, Pázmány P. s. 1/A, Budapest, 1117 (Hungary); Tremaine, Scott [Institute for Advanced Study, Princeton, NJ 08540 (United States)
2017-06-20
We examine dense self-gravitating stellar systems dominated by a central potential, such as nuclear star clusters hosting a central supermassive black hole. Different dynamical properties of these systems evolve on vastly different timescales. In particular, the orbital-plane orientations are typically driven into internal thermodynamic equilibrium by vector resonant relaxation before the orbital eccentricities or semimajor axes relax. We show that the statistical mechanics of such systems exhibit a striking resemblance to liquid crystals, with analogous ordered-nematic and disordered-isotropic phases. The ordered phase consists of bodies orbiting in a disk in both directions, with the disk thickness depending on temperature, while the disordered phase corresponds to a nearly isotropic distribution of the orbit normals. We show that below a critical value of the total angular momentum, the system undergoes a first-order phase transition between the ordered and disordered phases. At a critical point, the phase transition becomes second order, while for higher angular momenta there is a smooth crossover. We also find metastable equilibria containing two identical disks with mutual inclinations between 90° and 180°.
Isostructural magnetic phase transition and magnetocaloric effect in Ising antiferromagnet
International Nuclear Information System (INIS)
Lavanov, G.Yu; Kalita, V.M.; Loktev, V.M.
2014-01-01
It is shown that the external magnetic field induced isostructural I st order magnetic phase transition between antiferromagnetic phases with different antiferromagnetic vector values is associated with entropy. It is found, that depending on temperature the entropy jump and the related heat release change their sign at this transition point. In the low-temperature region of metamagnetic I st order phase tensition the entropy jump is positive, and in the triple point region this jump for isostructural magnetic transition is negative
Phase transitions and critical phenomena
Domb, Cyril
2001-01-01
The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. It has moved into a central place in condensed matter studies.Statistical physics, and more specifically, the theory of transitions between states of matter, more or less defines what we know about 'everyday' matter and its transformations.The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable in
An objective indicator for two-phase flow pattern transition
International Nuclear Information System (INIS)
Hervieua, E.; Seleghim, P. Jr.
1998-01-01
This work concerns the development of a methodology the objective of which is to characterize and diagnose two-phase flow regime transitions. The approach is based on the fundamental assumption that a transition flow is less stationary than a flow with an established regime. During the first time, the efforts focused on: (1) the design and construction of an experimental loop, allowing to reproduce the main horizontal two-phase flow patterns, in a stable and controlled way; (2) the design and construction of an electrical impedance probe, providing an imaged information of the spatial phase distribution in the pipe; and (3) the systematic study of the joint time-frequency and time-scale analysis methods, which permitted to define an adequate parameter quantifying the unstationarity degree. During the second time, in order to verify the fundamental assumption, a series of experiments were conducted, the objective of which was to demonstrate the correlation between unstationarity and regime transition. The unstationarity degree was quantified by calculating the Gabor's transform time-frequency covariance of the impedance probe signals. Furthermore, the phenomenology of each transition was characterized by the joint moments and entropy. The results clearly show that the regime transitions are correlated with local time-frequency covariance peaks, which demonstrates that these regime transitions are characterized by a loss of stationarity. Consequently, the time-frequency covariance constitutes an objective two-phase flow regime transition indicator. (orig.)
Discontinuity of maximum entropy inference and quantum phase transitions
International Nuclear Information System (INIS)
Chen, Jianxin; Ji, Zhengfeng; Yu, Nengkun; Zeng, Bei; Li, Chi-Kwong; Poon, Yiu-Tung; Shen, Yi; Zhou, Duanlu
2015-01-01
In this paper, we discuss the connection between two genuinely quantum phenomena—the discontinuity of quantum maximum entropy inference and quantum phase transitions at zero temperature. It is shown that the discontinuity of the maximum entropy inference of local observable measurements signals the non-local type of transitions, where local density matrices of the ground state change smoothly at the transition point. We then propose to use the quantum conditional mutual information of the ground state as an indicator to detect the discontinuity and the non-local type of quantum phase transitions in the thermodynamic limit. (paper)
Phase transitions in (NH4)2MoO2F4 crystal
Krylov, Alexander; Laptash, Natalia; Vtyurin, Alexander; Krylova, Svetlana
2016-11-01
The mechanisms of temperature and high pressure phase transitions have been studied by Raman spectroscopy. Room temperature (295 K) experiments under high hydrostatic pressure up to 3.6 GPa for (NH4)2 MoO2 F4 have been carried out. Experimental data indicates a phase transition into a new high-pressure phase for (NH4)2 MoO2 F4 at 1.2 GPa. This phase transition is related to the ordering anion octahedron groups [MoO2 F4]2- and is not associated with ammonium group. Raman spectra of small non-oriented crystals ranging from 10 to 350 K have been observed. The experiment shows anion groups [MoO2 F4]2- and ammonium in high temperature phase are disordered. The phase transition at T1 = 269.8 K is of the first-order, close to the tricritical point. The first temperature phase transition is related to the ordering anion octahedron groups [MoO2 F4]2-. Second phase transitions T2 = 180 K are associated with the ordering of ammonium. The data presented within this study demonstrate that 2D correlation analysis combined with traditional Raman spectroscopy are powerful tool to study phase transitions in the crystals.