WorldWideScience

Sample records for first-order electroweak phase

  1. First Order Electroweak Phase Transition from (Non)Conformal Extensions of the Standard Model

    DEFF Research Database (Denmark)

    Sannino, Francesco; Virkajärvi, Jussi

    2015-01-01

    We analyse and compare the finite-temperature electroweak phase transition properties of classically (non)conformal extensions of the Standard Model. In the classically conformal scenarios the breaking of the electroweak symmetry is generated radiatively. The models feature new scalars coupled...... conformally to the Higgs sector as well as new fermions. We uncover the parameter space leading to a first order phase transition with(out) the Veltman conditions. We also discuss dark (matter) aspects of some of the models and compare with existing literature when appropriate. We observe that to accommodate...

  2. A First-Order Electroweak Phase Transition in the Standard Model from Varying Yukawas

    CERN Document Server

    Baldes, Iason; Servant, Geraldine

    2016-01-01

    We show that the dynamics responsible for the variation of the Yukawa couplings of the Standard Model fermions generically leads to a very strong first-order electroweak phase transition, assuming that the Yukawa couplings are large and of order 1 before the electroweak phase transition and reach their present value afterwards. There are good motivations to consider that the flavour structure could emerge during electroweak symmetry breaking, for example if the Froggatt-Nielsen field dynamics were linked to the Higgs field. In this paper, we do not need to assume any particular theory of flavour and show in a model-independent way how the nature of the electroweak phase transition is completely changed when the Standard Model Yukawas vary at the same time as the Higgs is acquiring its vacuum expectation value. The thermal contribution of the fermions creates a barrier between the symmetric and broken phase minima of the effective potential, leading to a first-order phase transition. This offers new routes for...

  3. 750 GeV diphoton excess and strongly first-order electroweak phase transition

    Science.gov (United States)

    Perelstein, Maxim; Tsai, Yu-Dai

    2016-07-01

    A new scalar particle, coupled to photons and gluons via loops of vectorlike quarks, provides a simple theoretical interpretation of the 750 GeV diphoton excess reported by the experiments at the Large Hadron Collider (LHC). In this paper, we show that this model contains a large, phenomenologically viable parameter space region in which the electroweak phase transition (EWPT) is strongly first order, opening the possibility that the electroweak baryogenesis mechanism can be realized in this context. A large coupling between the Higgs doublet and the heavy scalar, required for a strongly first-order EWPT, can arise naturally in composite Higgs models. The scenario makes robust predictions that will be tested in near-future experiments. The cross section of resonant di-Higgs production at the 13 TeV LHC is predicted to be at least 20 fb, while the Higgs cubic self-coupling is enhanced by 40% or more with respect to its Standard Model (SM) value.

  4. Strongly first-order electroweak phase transition and classical scale invariance

    Science.gov (United States)

    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

  5. Magnetic Fields at First Order Phase Transition: A Threat to Electroweak Baryogenesis

    CERN Document Server

    De Simone, Andrea; Quiros, Mariano; Riotto, Antonio

    2011-01-01

    The generation of the observed baryon asymmetry may have taken place during the electroweak phase transition, thus involving physics testable at LHC, a scenario dubbed electroweak baryogenesis. In this paper we point out that the magnetic field which is produced in the bubbles of a first order phase transition endangers the baryon asymmetry produced in the bubble walls. The reason being that the produced magnetic field couples to the sphaleron magnetic moment and lowers the sphaleron energy; this strengthens the sphaleron transitions inside the bubbles and triggers a more effective wash out of the baryon asymmetry. We apply this scenario to the Minimal Supersymmetric extension of the Standard Model (MSSM) where, in the absence of a magnetic field, successful electroweak baryogenesis requires the lightest CP-even Higgs and the right-handed stop masses to be lighter than about 127 GeV and 120 GeV, respectively. We show that even for moderate values of the magnetic field, the Higgs mass required to preserve the ...

  6. 750 GeV Di-photon Excess and Strongly First-Order Electroweak Phase Transition

    CERN Document Server

    Perelstein, Maxim

    2016-01-01

    A new scalar particle, coupled to photons and gluons via loops of vector-like quarks, provides a simple theoretical interpretation of the 750 GeV di-photon excess reported by the experiments at the Large Hadron Collider (LHC). In this paper, we show that this model contains a large, phenomenologically viable parameter space region in which the electroweak phase transition (EWPT) is strongly first-order, opening the possibility that electroweak baryogenesis mechanism can be realized in this context. A large coupling between the Higgs doublet and the heavy scalar, required for a strongly first-order EWPT, can arise naturally in composite Higgs models. The scenario makes robust predictions that will be tested in near-future experiments. The cross section of resonant di-Higgs production at the 13 TeV LHC is predicted to be at least 20 fb, while the Higgs cubic self-coupling is enhanced by 40% or more with respect to its Standard Model (SM) value.

  7. Strong first order electroweak phase transition in the CP-conserving 2HDM revisited

    Science.gov (United States)

    Basler, P.; Krause, M.; Mühlleitner, M.; Wittbrodt, J.; Wlotzka, A.

    2017-02-01

    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.

  8. First-order electroweak phase transition powered by additional F-term loop effects in an extended supersymmetric Higgs sector

    CERN Document Server

    Kanemura, Shinya; Shindou, Tetsuo

    2011-01-01

    We investigate the one-loop effect of new charged scalar bosons on the Higgs potential at finite temperatures in the supersymmetric standard model with four Higgs doublet chiral superfields as well as a pair of charged singlet chiral superfields. In this model, the mass of the lightest Higgs boson $h$ is determined only by the D-term in the Higgs potential at the tree-level, while the triple Higgs boson coupling for $hhh$ can receive a significant radiative correction due to nondecoupling one-loop contributions of the additional charged scalar bosons. We find that the same nondecoupling mechanism can also contribute to realize stronger first order electroweak phase transition than that in the minimal supersymmetric standard model, which is definitely required for a successful scenario of electroweak baryogenesis. Therefore, this model can be a new candidate for a model in which the baryon asymmetry of the Universe is explained at the electroweak scale.

  9. A stochastic approach to thermal fluctuations during a first order electroweak phase transition

    CERN Document Server

    Illuminati, F

    1995-01-01

    We investigate the role played by subcritical bubbles at the onset of the electroweak phase transition. Treating the configuration modelling the thermal fluctuations around the homogeneous zero configuration of the Higgs field as a stochastic variable, we describe its dynamics by a phenomenological Langevin equation. This approach allows to properly take into account both the effects of the thermal bath on the system: a systematic dyssipative force, which tends to erase out any initial subcritical configuration, and a random stochastic force responsible for the fluctuations. We show that the contribution to the variance \\lgh\\phi^2(t)\\rg_V in a given volume V from any initial subcritical configuration is quickly damped away and that, in the limit of long times, \\lgh\\phi^2(t)\\rg_V approaches its equilibrium value provided by the stochastic force and independent from the viscosity coefficient, as predicted by the fluctuation-dissipation theorem. In agreement with some recent claims, we conclude that thermal fluc...

  10. Synergy between measurements of gravitational waves and the triple-Higgs coupling in probing the first-order electroweak phase transition

    Science.gov (United States)

    Hashino, Katsuya; Kakizaki, Mitsuru; Kanemura, Shinya; Matsui, Toshinori

    2016-07-01

    Probing the Higgs potential and new physics behind the electroweak symmetry breaking is one of the most important issues of particle physics. In particular, the nature of the electroweak phase transition is essential for understanding the physics of the early Universe, such that the strongly first-order phase transition is required for a successful scenario of electroweak baryogenesis. The strongly first-order phase transition is expected to be tested by precisely measuring the triple Higgs boson coupling at future colliders like the International Linear Collider. It can also be explored via the spectrum of stochastic gravitational waves to be measured at future space-based interferometers such as eLISA and DECIGO. We discuss the complementarity of both the methods in testing the strongly first-order phase transition of the electroweak symmetry in models with additional isospin singlet scalar fields with and without classical scale invariance. We find that they are synergetic in identifying specific models of electroweak symmetry breaking in more detail.

  11. Electroweak phase transition in technicolor

    CERN Document Server

    Jarvinen, Matti

    2010-01-01

    Several phenomenologically viable walking technicolor models have been proposed recently. I demonstrate that these models can have first order electroweak phase transitions, which are sufficiently strong for electroweak baryogenesis. Strong dynamics can also lead to several separate transitions at the electroweak scale, with the possibility of a temporary restoration and an extra breaking of the electroweak symmetry. First order phase transitions will produce gravitational waves, which may be detectable at future experiments.

  12. Gravitational waves from first-order cosmological phase transitions

    Science.gov (United States)

    Kosowsky, Arthur; Turner, Michael S.; Watkins, Richard

    1992-01-01

    A first-order cosmological phase transition that proceeds through the nucleation and collision of true-vacuum bubbles is a potent source of gravitational radiation. Possibilities for such include first-order inflation, grand-unified-theory-symmetry breaking, and electroweak-symmetry breaking. We have calculated gravity-wave production from the collision of two scalar-field vacuum bubbles, and, using an approximation based upon these results, from the collision of 20 to 30 vacuum bubbles. We present estimates of the relic background of gravitational waves produced by a first-order phase transition.

  13. 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.

  14. Gravitational Radiation from First-Order Phase Transitions

    CERN Document Server

    Child, Hillary L

    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, 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 that greatly enhances this radiation even in the absence of 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.

  15. Electroweak phase transitions

    CERN Document Server

    Fodor, Z

    2000-01-01

    Recent developments on the four dimensional (4d) lattice studies of the finite temperature electroweak phase transition (EWPT) are summarized. The phase diagram is given in the continuum limit. The finite temperature SU(2)-Higgs phase transition is of first order for Higgs-boson masses m/sub H/<66.5+or-1.4 GeV. Above this endpoint only a rapid cross-over can be seen. The full 4d result agrees completely with that of the dimensional reduction approximation. The Higgs-boson endpoint mass in the standard model (SM) would be 72.1+or-1. 4 GeV. Taking into account the LEP Higgs-boson mass lower bound excludes any EWPT in the SM. A one-loop calculation of the static potential in the SU(2)-Higgs model enables a precise comparison between lattice simulations and perturbative results. The most popular extension of the SM, the minimal supersymmetric SM (MSSM) is also studied on 4d lattices. (17 refs).

  16. Magnetocaloric materials and first order phase transitions

    DEFF Research Database (Denmark)

    Neves Bez, Henrique

    of the properties of such materials.The experimental characterization of these materials is done through various different methods, such as X-ray diffraction, magnetometry, calorimetry, direct measurements of entropy change, capacitance dilatometry, scanning electron microscopy,energy-dispersive X-ray spectrometry......This thesis studies the first order phase transitions of the magnetocaloric materials La0.67Ca0.33MnO3 and La(Fe,Mn,Si)13Hz trying to overcome challenges that these materials face when applied in active magnetic regenerators. The study is done through experimental characterization and modelling...... and magnetocaloric regenerative tests. The magnetic, thermal and structural properties obtained from such measurements are then evaluated through different models, i.e. the Curie-Weiss law, the Bean-Rodbell model, the free electron model and the Debye model.The measured magnetocaloric properties of La0.67Ca0.33MnO3...

  17. Defect Formation in First Order Phase Transitions with Damping

    CERN Document Server

    Ferrera, A

    1998-01-01

    Within the context of first order phase transitions in the early universe, we study the influence of a coupling between the (global U(1)) scalar driving the transition and the rest of the matter content of the theory. The effect of the coupling on the scalar is simulated by introducing a damping term in its equations of motion, as suggested by recent results in the electroweak phase transition. After a preceeding paper, in which we studied the influence that this coupling has in the dynamics of bubble collisions and topological defect formation, we proceed in this paper to quantify the impact of this new effects on the probability of defect creation per nucleating bubble.

  18. Magnetic Fields from the Electroweak Phase Transition

    CERN Document Server

    Törnkvist, O

    1998-01-01

    I review some of the mechanisms through which primordial magnetic fields may be created in the electroweak phase transition. I show that no magnetic fields are produced initially from two-bubble collisions in a first-order transition. The initial field produced in a three-bubble collision is computed. The evolution of fields at later times is discussed.

  19. Electroweak phase transition recent results

    CERN Document Server

    Csikor, Ferenc

    2000-01-01

    Recent results of four-dimensional (4d) lattice simulations on the finite temperature electroweak phase transition (EWPT) are discussed. The phase transition is of first order in the SU(2)-Higgs model below the end point Higgs mass 66.5$\\pm$1.4 GeV. For larger masses a rapid cross-over appears. This result completely agrees with the results of the dimensional reduction approach. Including the full Standard Model (SM) perturbatively the end point is at 72.1$\\pm$1.4 GeV. Combined with recent LEP Higgs mass lower bounds, this excludes any EWPT in the SM. A one-loop calculation of the static potential makes possible a precise comparison of the lattice and perturbative results. Recent 4d lattice studies of the Minimal Supersymmetric SM (MSSM) are also mentioned.

  20. Limiting First Order Phase Transitions in Dark Gauge Sectors from Gravitational Waves experiments

    CERN Document Server

    Addazi, Andrea

    2016-01-01

    We discuss the possibility to indirectly test First Order Phase Transitions of hidden sectors. We study the interesting example of a {\\it dark standard model} with a deformed parameter space in the Higgs potential. A dark electroweak phase transition can be limited from next future experiments like eLISA and DECIGO.

  1. Synergy between measurements of the gravitational wave and the triple Higgs coupling in probing first order phase transition

    CERN Document Server

    Hashino, Katsura; Kanemura, Shinya; Matsui, Toshinori

    2016-01-01

    Probing the Higgs potential and new physics behind the electroweak symmetry breaking is one of the most important issues of particle physics. In particular, nature of electroweak phase transition is essential for understanding physics at the early Universe, such that the strongly first order phase transition is required for a successful scenario of electroweak baryogenesis. The strongly first order phase transition is expected to be tested by precisely measuring the triple Higgs boson coupling at future colliders like the International Linear Collider. It can also be explored via the spectrum of stochastic gravitational waves to be measured at future space-based interferometers such as eLISA and DECIGO. We discuss complementarity of both the methods in testing the strongly first order phase transition of the electroweak symmetry in models with additional isospin singlet scalar fields with and without classical scale invariance. We find that they are synergetic in identifying specific models of electroweak sym...

  2. SUSY and the Electroweak Phase Transition

    CERN Document Server

    Farrar, Glennys R S; Farrar, Glennys R.; Losada, Marta

    1996-01-01

    We analyze the effective 3 dimensional theory previously constructed for the MSSM and multi-Higgs models to determine the regions of parameter space in which the electroweak phase transition is sufficiently strong for a $B+L$ asymmetry to survive in the low temperature phase. We find that the inclusion of all supersymmetric scalars and all 1-loop corrections has the effect of enhancing the strength of the phase transition. Without a light stop or extension of the MSSM the phase transition is sufficiently first order only if the lightest Higgs mass $M_{h}\\lsi 70$ GeV and $tan\\beta\\lsi 1.75$.

  3. End point of the electroweak phase transition

    CERN Document Server

    Csikor, Ferenc; Heitger, J; Aoki, Y; Ukawa, A

    1999-01-01

    We study the hot electroweak phase transition (EWPT) by 4-dimensional lattice simulations on lattices with symmetric and asymmetric lattice spacings and give the phase diagram. A continuum extrapolation is done. We find first order phase transition for Higgs-boson masses $m_H<66.5 \\pm 1.4$ GeV. Above this end point a rapid cross-over occurs. Our result agrees with that of the dimensional reduction approach. It also indicates that the fermionic sector of the Standard Model (SM) may be included perturbatively. We get for the SM end point $72.4 the SM.

  4. Landau Theory in the Region of First Order Phase Transitions

    Directory of Open Access Journals (Sweden)

    O.G. Medvedovskaya

    2014-04-01

    Full Text Available For the case when the line of the first order phase transitions does not transform into the line of the second order phase transitions, i.e. not as ends with the tricritical point but not with a critical one: critical lines, limiting the region of metastable states, by using the Landau theory of phase transitions were determined.

  5. Gravitational waves from deflagration bubbles in first-order phase transitions

    CERN Document Server

    Megevand, Ariel

    2008-01-01

    The walls of bubbles in a first-order phase transition can propagate either as detonations, with a velocity larger than the speed of sound, or deflagrations, which are subsonic. We calculate the gravitational radiation produced during a phase transition via deflagration bubbles. We take into account the fact that the deflagration wall is preceded by a shock front which distributes the latent heat throughout space and influences other bubbles. We show that turbulence can induce maximum values of $\\Omega_{GW}h^2$ as high as $\\sim 10^{-10}$. We discuss the possibility of detecting at LISA gravitational waves produced at the electroweak phase transition with wall velocities $v_w\\lesssim 10^{-1}$, which favor electroweak baryogenesis.

  6. Gravitational waves from cosmological first order phase transitions

    CERN Document Server

    Hindmarsh, Mark; Rummukainen, Kari; Weir, David

    2015-01-01

    First order phase transitions in the early Universe generate gravitational waves, which may be observable in future space-based gravitational wave observatiories, e.g. the European eLISA satellite constellation. The gravitational waves provide an unprecedented direct view of the Universe at the time of their creation. We study the generation of the gravitational waves during a first order phase transition using large-scale simulations of a model consisting of relativistic fluid and an order parameter field. We observe that the dominant source of gravitational waves is the sound generated by the transition, resulting in considerably stronger radiation than earlier calculations have indicated.

  7. Exploring first-order phase transitions with population annealing

    Science.gov (United States)

    Barash, Lev Yu.; Weigel, Martin; Shchur, Lev N.; Janke, Wolfhard

    2017-03-01

    Population annealing is a hybrid of sequential and Markov chain Monte Carlo methods geared towards the efficient parallel simulation of systems with complex free-energy landscapes. Systems with first-order phase transitions are among the problems in computational physics that are difficult to tackle with standard methods such as local-update simulations in the canonical ensemble, for example with the Metropolis algorithm. It is hence interesting to see whether such transitions can be more easily studied using population annealing. We report here our preliminary observations from population annealing runs for the two-dimensional Potts model with q > 4, where it undergoes a first-order transition.

  8. Endpoint of the hot electroweak phase transition

    CERN Document Server

    Csikor, Ferenc; Heitger, J

    1999-01-01

    We give the nonperturbative phase diagram of the four-dimensional hot electroweak phase transition. The Monte-Carlo analysis is done on lattices with different lattice spacings ($a$). A systematic extrapolation $a \\to 0$ is done. Our results show that the finite temperature SU(2)-Higgs phase transition is of first order for Higgs-boson masses $m_H<66.5 \\pm 1.4$ GeV. At this endpoint the phase transition is of second order, whereas above it only a rapid cross-over can be seen. The full four-dimensional result agrees completely with that of the dimensional reduction approximation. This fact is of particular importance, because it indicates that the fermionic sector of the Standard Model can be included perturbatively. We obtain that the Higgs-boson endpoint mass in the Standard Model is $72.4 \\pm 1.7$ GeV. Taking into account the LEP Higgs-boson mass lower bound excludes any electroweak phase transition in the Standard Model.

  9. Higgs Couplings and Electroweak Phase Transition

    CERN Document Server

    Katz, Andrey

    2014-01-01

    We argue that extensions of the Standard Model (SM) with a strongly first-order electroweak phase transition generically predict significant deviations of the Higgs couplings to gluons, photons, and Z bosons from their SM values. Precise experimental measurements of the Higgs couplings at the LHC and at the proposed next-generation facilities will allow for a robust test of the phase transition dynamics. To illustrate this point, in this paper we focus on the scenario in which loops of a new scalar field are responsible for the first-order phase transition, and study a selection of benchmark models with various SM gauge quantum numbers of the new scalar. We find that the current LHC measurement of the Higgs coupling to gluons already excludes the possibility of a first-order phase transition induced by a scalar in a sextet, or larger, representation of the SU(3)_c. Future LHC experiments (including HL-LHC) will be able to definitively probe the case when the new scalar is a color triplet. If the new scalar is...

  10. Probing the Electroweak Phase Transition with Higgs Factories and Gravitational Waves

    CERN Document Server

    Huang, Peisi; Wang, Lian-Tao

    2016-01-01

    After the discovery of the Higgs boson, understanding the nature of electroweak symmetry breaking and the associated electroweak phase transition has become the most pressing question in particle physics. Answering this question is a priority for experimental studies. Data from the LHC and future lepton collider-based Higgs factories may uncover new physics coupled to the Higgs boson, which can induce the electroweak phase transition to become first order. Such a phase transition generates a stochastic background of gravitational waves, which could potentially be detected by a space-based gravitational wave interferometer. In this paper, we survey a few classes of models in which the electroweak phase transition is strongly first order. We identify the observables that would provide evidence of these models at the LHC and next-generation lepton colliders, and we assess whether the corresponding gravitational wave signal could be detected by eLISA. We find that most of the models with first order electroweak p...

  11. Second- and First-Order Phase Transitions in CDT

    CERN Document Server

    Ambjorn, J; Jurkiewicz, J; Loll, R

    2012-01-01

    Causal Dynamical Triangulations (CDT) is a proposal for a theory of quantum gravity, which implements a path-integral quantization of gravity as the continuum limit of a sum over piecewise flat spacetime geometries. We use Monte Carlo simulations to analyse the phase transition lines bordering the physically interesting de Sitter phase of the four-dimensional CDT model. Using a range of numerical criteria, we present strong evidence that the so-called A-C transition is first order, while the B-C transition is second order. The presence of a second-order transition may be related to an ultraviolet fixed point of quantum gravity and thus provide the key to probing physics at and possibly beyond the Planck scale.

  12. Kinetics of first-order phase transitions with correlated nuclei

    Science.gov (United States)

    Rickman, J. M.; Barmak, K.

    2017-02-01

    We demonstrate that the time evolution of a first-order phase transition may be described quite generally in terms of the statistics of point processes, thereby providing an intuitive framework for visualizing transition kinetics. A number of attractive and repulsive nucleation scenarios is examined followed by isotropic domain growth at a constant rate This description holds for both uncorrelated and correlated nuclei, and may be employed to calculate the nonequilibrium, n -point spatiotemporal correlations that characterize the transition. Furthermore, it is shown that the interpretation of the one-point function in terms of a stretched-exponential, Kolmogorov-Johnson-Mehl-Avrami result is problematic in the case of correlated nuclei, but that the calculation of higher-order correlation functions permits one to distinguish among various nucleation scenarios.

  13. Numerical simulations of acoustically generated gravitational waves at a first order phase transition

    Science.gov (United States)

    Hindmarsh, Mark; Huber, Stephan J.; Rummukainen, Kari; Weir, David J.

    2015-12-01

    We present details of numerical simulations of the gravitational radiation produced by a first order thermal phase transition in the early Universe. We confirm that the dominant source of gravitational waves is sound waves generated by the expanding bubbles of the low-temperature phase. We demonstrate that the sound waves have a power spectrum with a power-law form between the scales set by the average bubble separation (which sets the length scale of the fluid flow Lf) and the bubble wall width. The sound waves generate gravitational waves whose power spectrum also has a power-law form, at a rate proportional to Lf and the square of the fluid kinetic energy density. We identify a dimensionless parameter Ω˜GW characterizing the efficiency of this "acoustic" gravitational wave production whose value is 8 π Ω˜GW≃0.8 ±0.1 across all our simulations. We compare the acoustic gravitational waves with the standard prediction from the envelope approximation. Not only is the power spectrum steeper (apart from an initial transient) but the gravitational wave energy density is generically larger by the ratio of the Hubble time to the phase transition duration, which can be 2 orders of magnitude or more in a typical first order electroweak phase transition.

  14. Echoes of inflationary first-order phase transitions in the CMB

    Directory of Open Access Journals (Sweden)

    Hongliang Jiang

    2017-02-01

    Full Text Available Cosmological phase transitions (CPTs, such as the Grand Unified Theory (GUT and the electroweak (EW ones, play a significant role in both particle physics and cosmology. In this letter, we propose to probe the first-order CPTs, by detecting gravitational waves (GWs which are generated during the phase transitions through the cosmic microwave background (CMB. If happened around the inflation era, the first-order CPTs may yield low-frequency GWs due to bubble dynamics, leaving imprints on the CMB. In contrast to the nearly scale-invariant primordial GWs caused by vacuum fluctuation, these bubble-generated GWs are scale dependent and have non-trivial B-mode spectra. If decoupled from inflaton, the EWPT during inflation may serve as a probe for the one after reheating where the baryon asymmetry could be generated via EW baryogenesis (EWBG. The CMB thus provides a potential way to test the feasibility of the EWBG, complementary to the collider measurements of Higgs potential and the direct detection of GWs generated during EWPT.

  15. Where does the hot electroweak phase transition end?

    CERN Document Server

    Csikor, Ferenc; Heitger, J

    1999-01-01

    We give the nonperturbative phase diagram of the four-dimensional hot electroweak phase transition. A systematic extrapolation $a \\to 0$ is done. Our results show that the finite temperature SU(2)-Higgs phase transition is of first order for Higgs-boson masses $m_H<66.5 \\pm 1.4$ GeV. The full four-dimensional result agrees completely with that of the dimensional reduction approximation. This fact is of particular importance, because it indicates that the fermionic sector of the Standard Model (SM) can be included perturbatively. We obtain that the Higgs-boson endpoint mass in the SM is $72.4 any electroweak phase transition in the SM.

  16. Electroweak phase transition and baryogenesis in the nMSSM

    Energy Technology Data Exchange (ETDEWEB)

    Huber, Stephan J. [Theory Division, CERN, CH-1211 Geneva 23 (Switzerland)]. E-mail: stephan.huber@cern.ch; Konstandin, Thomas [Department of Physics, Royal Institute of Technology (KTH), AlbaNova University Center, Roslagstullsbacken 11, 106 91 Stockholm (Sweden)]. E-mail: konstand@theophys.kth.se; Prokopec, Tomislav [Institute for Theoretical Physics (ITF) and Spinoza Institute, Utrecht University, Leuvenlaan 4, Postbus 80.195, 3508 TD Utrecht (Netherlands)]. E-mail: t.prokopec@phys.uu.nl; Schmidt, Michael G. [Institut fuer Theoretische Physik, Heidelberg University, Philosophenweg 16, D-69120 Heidelberg (Germany)]. E-mail: m.g.schmidt@thphys.uni-heidelberg.de

    2006-11-20

    We analyze the nMSSM with CP violation in the singlet sector. We study the static and dynamical properties of the electroweak phase transition. We conclude that electroweak baryogenesis in this model is generic in the sense that if the present limits on the mass spectrum are applied, no severe additional tuning is required to obtain a strong first-order phase transition and to generate a sufficient baryon asymmetry. For this we determine the shape of the nucleating bubbles, including the profiles of CP-violating phases. The baryon asymmetry is calculated using the advanced transport theory to first and second order in gradient expansion presented recently. Still, first and second generation sfermions must be heavy to avoid large electric dipole moments.

  17. Electroweak phase transition and some related phenomena – a brief review

    Indian Academy of Sciences (India)

    BUDDHADEB GHOSH

    2016-09-01

    In this article, we give a bird’s eye view of the research on electroweak phase transition and some related phenomena, viz., cosmological baryogenesis, electroweak bubble dynamics and generation of gravitationalwaves. Our presentation revolves around the observation that a strong first-order electroweak phase transition cannot be obtained in the Standard Model for experimentally favoured Higgs mass and hence the cosmologicalevents associated with this kind of phase transition cannot be explained in this model. However, this phase transition can be achieved in a number of beyond Standard Models. As a prototype case, we consider the littlest Higgs model with T parity and show the results of some calculations within this model.

  18. Gravitational waves and Higgs boson couplings for exploring first order phase transition in the model with a singlet scalar field

    Science.gov (United States)

    Hashino, Katsuya; Kakizaki, Mitsuru; Kanemura, Shinya; Ko, Pyungwon; Matsui, Toshinori

    2017-03-01

    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.

  19. Gravitational waves and Higgs boson couplings for exploring first order phase transition in the model with a singlet scalar field

    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.

  20. The Evolution of Elliptic Flow Under First Order Phase Transition

    Institute of Scientific and Technical Information of China (English)

    冯启春; 王清尚; 刘剑利; 任延宇; 张景波; 霍雷

    2012-01-01

    Elliptic flow for non-central Au+Au collisions at √SNN=200 GeV is investigated with a 2+1 dimensional hydrodynamic model. We analyze the softening effect by the velocity along the axis. The contribution of the elliptic flow from the QGP phase, mixed phase and hadron gas phase is studied. The relation between the sound horizon and evolution of the elliptic flow is discussed.

  1. Light Dark Matter, Light Higgs and the Electroweak Phase Transition

    CERN Document Server

    Ahriche, Amine

    2012-01-01

    We propose a minimal extension of the Standard Model by two real singlet fields that could provide a good candidate for light Dark Matter, and giving a strong first order electroweak phase transition. As a result, there are two Higgs bosons; one is lighter than <140 GeV, and the other one with mass in the range: 300- 350 GeV and which are consistent with electroweak precision tests. We show that the lightest Higgs mass can be as small as 35 GeV while still being consistent with the LEP data. The predicted dark matter scattering cross section is large enough to accommodate CoGeNT and be can probed by future XENON experiment. We also show that for dark matter with mass: 2 GeV the B-factories.

  2. Supercooling across first-order phase transitions in vortex matter

    Indian Academy of Sciences (India)

    P Chaddah; S B Roy

    2000-06-01

    Hysteresis in cycling through first-order phase transitions in vortex matter, akin to the well-studied phenomenon of supercooling of water, has been discussed in literature. Hysteresis can be seen while varying either temperature or magnetic field (and thus the density of vortices). Our recent work on phase transitions with two control variables shows that the observable region of metastability of the supercooled phase would depend on the path followed in - space, and will be larger when is lowered at constant compared to the case when is lowered at constant . We discuss the effect of isothermal field variations on metastable supercooled states produced by field-cooling. This path dependence is not a priori applicable to metastability caused by reduced diffusivity or hindered kinetics.

  3. Windowed phase unwrapping using a first-order dynamic system following iso-phase contours.

    Science.gov (United States)

    Estrada, Julio C; Vargas, Javier; Flores-Moreno, J Mauricio; Quiroga, J Antonio

    2012-11-01

    In this work, we show a windowed phase-unwrapping technique that uses a first-order dynamic system and scans the phase following its iso-phase contours. In previous works, we have shown that low-pass first-order dynamic systems are very robust and useful in phase-unwrapping problems. However, it is well known that all phase-unwrapping methods have a minimum signal-to-noise ratio that they tolerate. This paper shows that scanning the phase within local windows and using a path following strategy, the first-order unwrapping method increases its tolerance to noise. In this way, using the improved approach, we can unwrap phase maps where the basic dynamic phase-unwrapping system fails. Tests and results are given, as well as the source code in order to show the performance of the proposed method.

  4. Electroweak Phase Transition in the U(1)'-MSSM

    CERN Document Server

    Ahriche, Amine

    2010-01-01

    In this work, we have investigated the nature of the electroweak phase transition (EWPT) in the U(1) extended Minimal Supersymmetric Standard Model (UMSSM) without introducing any exotic filds. The effective potential has been estimated exactly at finite temperature taking into account the whole particle spectrum. For reasonable values of the lightest Higgs and neutralino, we found that the EWPT could be strongly first order due to: 1) the interactions of the singlet with the doublets in the effective potential, and 2) the evolution of the wrong vacuum, that delays the transition.

  5. First order thermal phase transition with 126 GeV Higgs mass

    CERN Document Server

    Laine, M; Rummukainen, K

    2013-01-01

    We study the strength of the electroweak phase transition in models with two light Higgs doublets and a light SU(3)_c triplet by means of lattice simulations in a dimensionally reduced effective theory. In the parameter region considered the transition on the lattice is significantly stronger than indicated by a 2-loop perturbative analysis. Within some ultraviolet uncertainties, the finding applies to MSSM with a Higgs mass m_h approximately 126 GeV and shows that the parameter region useful for electroweak baryogenesis is enlarged. In particular (even though only dedicated analyses can quantify the issue), the tension between LHC constraints after the 7 TeV and 8 TeV runs and frameworks where the electroweak phase transition is driven by light stops, seems to be relaxed.

  6. Charge asymmetry from C P -violating fermion scattering off bubble walls during the electroweak phase transition

    Science.gov (United States)

    Ayala, Alejandro; Hernández, L. A.; Salinas, Jordi

    2017-06-01

    We compute the net electric current generated during a first order electroweak phase transition when fermions transit from the false to the true vacuum. This current is generated by the charge parity conjugation (C P )-violating fermion interaction with the Higgs field during the phase transition and is quantified in terms of a C P -violating phase in the bubble wall separating the symmetric from the symmetry-broken phases. We comment on the seed magnetic field that this current is able to generate, and it is possible implications for magnetogenesis in the early Universe during the electroweak phase transition.

  7. Inhomogeneous field configurations and the electroweak phase transition

    CERN Document Server

    Jungnickel, D U; Jungnickel, Dirk-Uwe; Walliser, Dirk

    1994-01-01

    We investigate the effects of inhomogeneous scalar field configurations on the electroweak phase transition. For this purpose we calculate the leading perturbative correction to the wave function correction term $Z(\\vph,T)$, i.e., the kinetic term in the effective action, for the electroweak Standard Model at finite temperature and the top quark self--mass. Our finding for the fermionic contribution to $Z(\\vph,T)$ is infra--red finite and disagrees with other recent results. In general, neither the order of the phase transition nor the temperature at which it occurs change, once $Z(\\vph,T)$ is included. But a non--vanishing, positive (negative) $Z(\\vph,T)$ enhances (decreases) the critical droplet surface tension and the strength of the phase transition. We find that in the range of parameter space, which allows for a first--order phase transition, the wave function correction term is negative --- indicating a weaker phase transition --- and especially for small field values so large that perturbation theory ...

  8. Cosmic $\\Delta B$ from Lepton Violating Interactions at the Electroweak Phase Transition

    CERN Document Server

    Masiero, A; Masiero, Antonio; Riotto, Antonio

    1992-01-01

    We propose a new mechanism for late cosmological baryon asymmetry in models with first order electroweak phase transition. Lepton asymmetry arises through the decay of particles produced out of equilbrium in bubble collisions and is converted into baryon asymmetry by sphalerons. Supersymmetric models with explicitly broken R-parity may provide a suiatble framework for the implementation of this mechanism.

  9. New Insights of Electroweak Phase Transition in NMSSM

    CERN Document Server

    Huang, Weicong; Shu, Jing; Wu, Peiwen; Yang, Jin Min

    2014-01-01

    We perform a detailed semi-analytical analysis of the electroweak phase transition (EWPT) property in NMSSM, which serves as a good benchmark model in which the 126 GeV Higgs mixes with a singlet. In this case, a strongly first order electroweak phase transition (SFOEWPT) is achieved by the tree-level effects and the phase transition strength $\\gamma_c$ is determined by the vacua energy gap at $T=0$. We make an anatomy of the energy gap at both tree-level and loop-level and extract out a dimensionless phase transition parameter $R_\\kappa \\equiv 4 \\kappa v_s / A_\\kappa$, which can replace $A_\\kappa$ in the parameterization and affect the light CP odd and even Higgs spectra. We find that SFOEWPT only occurs in $R_\\kappa \\sim -1$ and positive $R_\\kappa \\lesssim \\mathcal{O}(10)$, which in the non-PQ limit case would prefer either a relatively light CP odd or CP even Higgs boson $\\sim (60, 100)$ GeV, therefore serves as a smoking gun signal and requires new search strategies at the LHC.

  10. Phase fluctuations and first-order correlation functions of dissipative Bose-Einstein condensates

    NARCIS (Netherlands)

    De Leeuw, A. W.; Stoof, H. T C; Duine, R. A.

    2014-01-01

    We investigate the finite-lifetime effects on first-order correlation functions of dissipative Bose-Einstein condensates. By taking into account the phase fluctuations up to all orders, we show that the finite-lifetime effects are negligible for the spatial first-order correlation functions, but hav

  11. The electroweak phase transition in models with gauge singlets

    Energy Technology Data Exchange (ETDEWEB)

    Ahriche, A.

    2007-04-18

    A strong first order phase transition is needed for generating the baryon asymmetry; and also to save it during the electroweak phase transition (EWPT). However this condition is not fulfilled within the Standard Model (SM), but in its extensions. It is widely believed that the existence of singlet scalars in some Standard Model extensions can easily make the EWPT strongly first order. In this work, we will examine the strength of the EWPT in the simplest extension of the SM with a real gauge singlet using the sphaleron energy at the critical temperature. We find that the phase transition is stronger by adding a singlet; and also that the criterion for a strong phase transition {omega}(T{sub c})/T{sub c} >or similar 1, where {omega} = (v{sup 2} + (x - x{sub 0}){sup 2}){sup (}1)/(2) and x(x{sub 0}) is the singlet vacuum expectation value in the broken (symmetric) phase, is not valid for models containing singlets, even though often used in the literature. The usual condition v{sub c}/T{sub c} >or similar 1 is more meaningful, and it is satisfied for the major part of the parameter space for physically allowed Higgs masses. Then it is convenient to study the EWPT in models with singlets that couple only to the Higgs doublets, by replacing the singlets by their vevs. (orig.)

  12. Gravitational waves and Higgs boson couplings for exploring first order phase transition in the model with a singlet scalar field

    CERN Document Server

    Hashino, Katsuya; Kanemura, Shinya; Ko, Pyungwon; Matsui, Toshinori

    2016-01-01

    We calculate the spectrum of gravitational waves originated from strongly first order electroweak phase transition in the extended Higgs model with a real singlet field. In order to calculate the bubble nucleation rate, we perform a two-field analysis to 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. Th...

  13. Electroweak phase transition in the economical 3-3-1 model

    CERN Document Server

    Phong, Vo Quoc; Van, Vo Thanh; Minh, Le Hoang

    2014-01-01

    Following our approach to the electroweak phase transition (EWPT), we consider the phase transitions in framework of the economical 3-3-1 model (E331). Structure of phase transition in this model is divided into two periods. The first period is the phase transition $SU(3) \\rightarrow SU(2)$ at TeV scale and the second one is $SU(2) \\rightarrow U(1)$, which is like the Standard Model (SM) electroweak phase transition. Two periods are the first-order phase transitions if the masses of heavy bosons is equal to few TeVs and the mass of second neutral Higgs is, $0phase transition period is $1<\\omega<5$ TeV. In addition, we also derived conditions of the self interaction parameters in the Higgs potential. Therefore, new bosons are the triggers of the first-order electroweak phase transition with significant implications for the viability of electroweak baryogenesis scenarios in this model.

  14. First-order phase transition in $1d$ Potts model with long-range interactions

    OpenAIRE

    Uzelac, K.; Glumac, Z.

    1998-01-01

    The first-order phase transition in the one-dimensional $q$-state Potts model with long-range interactions decaying with distance as $1/r^{1+\\sigma}$ has been studied by Monte Carlo numerical simulations for $0 2$. On the basis of finite-size scaling analysis of interface free energy $\\Delta F_L$, specific heat and Binder's fourth order cumulant, we obtain the first-order transition which occurs for $\\sigma$ below a threshold value $\\sigma_c(q)$.

  15. Effects of Two Inert Scalar Doublets on Higgs Interactions and Electroweak Phase Transition

    CERN Document Server

    Ahriche, Amine; Ho, Shu-Yu; Nasri, Salah; Tandean, Jusak

    2015-01-01

    We study some implications of the presence of two inert scalar doublets which are charged under a dark Abelian gauge symmetry. Specifically, we investigate the effects of the new scalars on oblique electroweak parameters and on the interactions of the 125 GeV Higgs boson, especially its decay modes $h\\to\\gamma\\gamma,\\gamma Z$, and trilinear coupling, all of which will be probed with improved precision in future Higgs measurements. Moreover, we explore how the inert scalars may give rise to strongly first-order electroweak phase transition and also show its correlation with sizable modifications to the Higgs trilinear coupling.

  16. On entropy change measurements around first order phase transitions in caloric materials

    Science.gov (United States)

    Caron, Luana; Doan, Nguyen Ba; Ranno, Laurent

    2017-02-01

    In this work we discuss the measurement protocols for indirect determination of the isothermal entropy change associated with first order phase transitions in caloric materials. The magneto-structural phase transitions giving rise to giant magnetocaloric effects in Cu-doped MnAs and FeRh are used as case studies to exemplify how badly designed protocols may affect isothermal measurements and lead to incorrect entropy change estimations. Isothermal measurement protocols which allow correct assessment of the entropy change around first order phase transitions in both direct and inverse cases are presented.

  17. Thermodynamics around the first-order ferromagnetic phase transition of Fe2P single crystals

    NARCIS (Netherlands)

    Hudl, M.; Campanini, D.; Caron, L.; Höglin, V.; Sahlberg, M.; Nordblad, P.; Rydh, A.

    2014-01-01

    The specific heat and thermodynamics of Fe2P single crystals around the first-order paramagnetic to ferromagnetic (FM) phase transition at TC≃217K are empirically investigated. The magnitude and direction of the magnetic field relative to the crystal axes govern the derived H−T phase diagram. Striki

  18. Gravitational Waves from the Phase Transition of a Non-linearly Realised Electroweak Gauge Symmetry

    CERN Document Server

    Kobakhidze, Archil; Yue, Jason

    2016-01-01

    Within the Standard Model with non-linearly realised electroweak symmetry, the LHC Higgs boson may reside in a singlet representation of the gauge group. Several new interactions are then allowed, including anomalous Higgs self-couplings, which may drive the electroweak phase transition to be strongly first-order. In this paper we investigate the cosmological electroweak phase transition in a simplified model with an anomalous Higgs cubic self- coupling. We look at the feasibility of detecting gravitational waves produced during such a transition in the early universe by future space-based experiments. We find that for the range of relatively large cubic couplings, $111~{\\rm GeV}~ \\lesssim |\\kappa| \\lesssim 118~{\\rm GeV}$, $\\sim $mHz frequency gravitational waves can be observed by eLISA, while BBO will potentially be able to detect waves in a wider frequency range, $0.1-10~$mHz.

  19. Simple empirical order parameter for a first-order quantum phase transition in atomic nuclei.

    Science.gov (United States)

    Bonatsos, Dennis; McCutchan, E A; Casten, R F; Casperson, R J

    2008-04-11

    A simple, empirical, easy-to-measure effective order parameter of a first-order phase transition in atomic nuclei is presented, namely, the ratio of the energies of the first excited 6+ and 0+ states, distinguishing between first- and second-order transitions, and taking on a special value in the critical region, as data in Nd-Dy show. In the large NB limit of the interacting boson approximation model, a repeating degeneracy between alternate yrast and successive 0+ states is found in the critical region around the line of a first-order phase transition, pointing to a possible underlying symmetry.

  20. First order magneto-structural transition in functional magnetic materials: phase-coexistence and metastability

    Indian Academy of Sciences (India)

    S B Roy; M K Chattopadhyay; M A Manekar; K J S Sokhey; P Chaddah

    2006-11-01

    First order magneto-structural transition plays an important role in the functionality of various magnetic materials of current interest like manganese oxide systems showing colossal magnetoresistance, Gd5(Ge, Si)4 alloys showing giant magnetocaloric effects and magnetic shape memory alloys. The key features of this magneto-structural transition are phase-coexistence and metastability. This generality is highlighted with experimental results obtained in a particular class of materials. A generalized framework of disorder influenced first order phase transition is introduced to understand the interesting experimental results which have some bearing on the functionality of the concerned materials.

  1. Colored Noise in First-order-like Phase Transition of a Laser System

    Institute of Scientific and Technical Information of China (English)

    HE Ying; ZHU Shiqun; LING Yinsheng

    2002-01-01

    The decoupling theory is employed to analyze the multiplicative colored noise in a single mode laser system. Steady state intensity distribution function is derived when colored noise is included in the laser system. The first-order-like phase transition driven by multiplicative colored noise is investigated and compared with the case of multiplicative white noise. It is shown that the noise correlation time can affect the parameter plane of the first-order-like phase transition. The steady state intensity distributions in a laser system is changed greatly with noise correlation time τ.

  2. Nonequilibrium and nonhomogeneous phenomena around a first-order quantum phase transition

    Science.gov (United States)

    Del Re, Lorenzo; Fabrizio, Michele; Tosatti, Erio

    2016-03-01

    We consider nonequilibrium phenomena in a very simple model that displays a zero-temperature first-order phase transition. The quantum Ising model with a four-spin exchange is adopted as a general representative of first-order quantum phase transitions that belong to the Ising universality class, such as for instance the order-disorder ferroelectric transitions, and possibly first-order T =0 Mott transitions. In particular, we address quantum quenches in the exactly solvable limit of infinite connectivity and show that, within the coexistence region around the transition, the system can remain trapped in a metastable phase, as long as it is spatially homogeneous so that nucleation can be ignored. Motivated by the physics of nucleation, we then study in the same model static but inhomogeneous phenomena that take place at surfaces and interfaces. The first-order nature implies that both phases remain locally stable across the transition, and with that the possibility of a metastable wetting layer showing up at the surface of the stable phase, even at T =0 . We use mean-field theory plus quantum fluctuations in the harmonic approximation to study quantum surface wetting.

  3. Aspects of the electroweak phase transition in the Minimal Supersymmetric Standard Model

    CERN Document Server

    Brignole, A; Quirós, Mariano; Zwirner, F

    1994-01-01

    We study the finite-temperature effective potential of the Minimal Supersymmetric Standard Model in the full (mA, tan(beta)) parameter space. As for the features of the electroweak phase transition, we identify two possible sources of significant differences with respect to the Standard Model: a stop sector with little supersymmetry breaking makes the phase transition more strongly first-order, whereas a light CP-odd neutral boson weakens its first-order nature. After including the leading plasma effects, T=0 radiative corrections due to top and stop loops, and the most important experimental constraints, we find that the danger of washing out any baryon asymmetry created at the electroweak scale is in general no less than in the Standard Model.

  4. Exit from inflation with a first-order phase transition and a gravitational wave blast

    Directory of Open Access Journals (Sweden)

    Amjad Ashoorioon

    2015-07-01

    Full Text Available In double-field inflation, which exploits two scalar fields, one of the fields rolls slowly during inflation whereas the other field is trapped in a meta-stable vacuum. The nucleation rate from the false vacuum to the true one becomes substantial enough that triggers a first order phase transition and ends inflation. We revisit the question of first order phase transition in an “extended” model of hybrid inflation, realizing the double-field inflationary scenario, and correctly identify the parameter space that leads to a first order phase transition at the end of inflation. We compute the gravitational wave profile which is generated during this first order phase transition. Assuming instant reheating, the peak frequency falls in the 1 GHz to 10 GHz frequency band and the amplitude varies in the range 10−11≲ΩGWh2≲10−8, depending on the value of the cosmological constant in the false vacuum. For a narrow band of vacuum energies, the first order phase transition can happen after the end of inflation via the violation of slow-roll, with a peak frequency that varies from 1 THz to 100 THz. For smaller values of cosmological constant, even though inflation can end via slow-roll violation, the universe gets trapped in a false vacuum whose energy drives a second phase of eternal inflation. This range of vacuum energies do not lead to viable inflationary models, unless the value of the cosmological constant is compatible with the observed value, M∼10−3 eV.

  5. On a First-Order Quantum Phase Transition in a Finite System

    CERN Document Server

    Leviatan, A

    2006-01-01

    We examine the dynamics at the critical-point of a general first-order quantum phase transition in a finite system. Suitable Hamiltonians are constructed whose spectra exhibit coexistence of states corresponding to two degenerate minima in the energy surface separated by an arbitrary barrier. Explicit expressions are derived for wave functions and obesrvables at the critical-point.

  6. Nature of the first-order magnetic phase transition in giant-magnetocaloric materials

    NARCIS (Netherlands)

    Yibole

    2016-01-01

    This thesis reports on advanced characterizations of giant magnetocaloric materials that show a first order magnetic phase transition (FOMT). The results are of great interest not only for the design of new magnetic refrigerants, but also for a better understanding of the FOMT. This thesis paves the

  7. First-order phase transitions in rotating hybrid stars and pulsar glitches

    Institute of Scientific and Technical Information of China (English)

    Fei Xiao; Chun-Mei Pi; Shu-Hua Yang; Ai-Zhi Zhou; Xiao-Ping Zheng

    2011-01-01

    The first order deconfinement phase transitions in rotating hybrid stars are studied and it is found that if the surface tension is sufficiently large, the transition from metastable hadron matter to stable mixed hadron-quark matter during the spindown history of a hybrid star can cause a glitch.

  8. Regularity and chaos at critical points of first-order quantum phase transitions

    CERN Document Server

    Macek, Michal

    2011-01-01

    We study the interplay between regular and chaotic dynamics at the critical point of a first order quantum shape-phase transition in an interacting boson model of nuclei. A classical analysis reveals a distinct behavior of the coexisting phases in a broad energy range. The dynamics is completely regular in the deformed phase while it becomes strongly chaotic in the spherical phase. A quantum analysis of the spectra separates the regular states from the irregular ones, assigns them to particular phases and discloses persisting regular rotational bands in the deformed region.

  9. Spin-down of compact stars and energy release of a first-order phase transition

    CERN Document Server

    Miao, Kang; Na-Na, Pan

    2007-01-01

    The deconfinement phase transition from hadronic matter to quark matter can continuously occur during spins down of neutron stars. It will lead to the release of latent heat if the transition is the first-order one. We have investigated the energy release of such deconfinement phase transition for rotating hybrid stars model which include mixed phase of hadronic matter and quark matter. The release of latent heat per baryon is calculated through studying a randomly process of infinitesimal compressing. Finally, we can self-consistently get the heating luminosity of deconfinement phase transition by imputing the EOS of mixed phase, and based on the equation of rotation structure of stars.

  10. Gravitational waves from the first order phase transition of the Higgs field at high energy scales

    Science.gov (United States)

    Jinno, Ryusuke; Nakayama, Kazunori; Takimoto, Masahiro

    2016-02-01

    In a wide class of new physics models, there exist scalar fields that obtain vacuum expectation values of high energy scales. We study the possibility that the standard model Higgs field has experienced first order phase transition at the high energy scale due to the couplings with these scalar fields. We estimate the amount of gravitational waves produced by the phase transition, and discuss observational consequences.

  11. Gravitational Waves from the First Order Phase Transition of the Higgs Field at High Energy Scales

    CERN Document Server

    Jinno, Ryusuke; Takimoto, Masahiro

    2015-01-01

    In a wide class of new physics models, there exist scalar fields which obtain vacuum expectation values of high energy scales. We study the possibility that the standard model Higgs field has experienced first-order phase transition at the high energy scale due to the couplings with these scalar fields.We estimate the amount of gravitational waves produced by the phase transition, and discuss observational consequences.

  12. First-order corrections to random-phase approximation GW calculations in silicon and diamond

    Science.gov (United States)

    Ummels, R. T. M.; Bobbert, P. A.; van Haeringen, W.

    1998-05-01

    We report on ab initio calculations of the first-order corrections in the screened interaction W to the random-phase approximation polarizability and to the GW self-energy, using a noninteracting Green's function, for silicon and diamond. It is found that the first-order vertex and self-consistency corrections to the polarizability largely compensate each other. This does not hold, however, for the first-order corrections to the GW gap. For silicon the compensation between the first-order vertex and self-consistency correction contributions to the gap is only about 35%, while for diamond it is even absent. The resulting gap values are significantly and systematically too large, the direct gaps for silicon and diamond being 0.4 eV and 0.7 eV larger than their GW values, respectively. The success of GW in predicting electronic properties of, e.g., silicon and diamond can therefore apparently not be understood in terms of ``small'' corrections to GW to first order in W using a noninteracting Green's function.

  13. Destruction of first-order phase transition in a random-field Ising model

    Energy Technology Data Exchange (ETDEWEB)

    Crokidakis, Nuno; Nobre, Fernando D [Centro Brasileiro de Pesquisas Fisicas, Rua Xavier Sigaud 150, 22290-180, Rio de Janeiro-RJ (Brazil)], E-mail: nuno@if.uff.br, E-mail: fdnobre@cbpf.br

    2008-04-09

    The phase transitions that occur in an infinite-range-interaction Ising ferromagnet in the presence of a double Gaussian random magnetic field are analyzed. Such random fields are defined as a superposition of two Gaussian distributions, presenting the same width {sigma}. It is argued that this distribution is more appropriate for a theoretical description of real systems than other simpler cases, i.e. the bimodal ({sigma} = 0) and single Gaussian distributions. It is shown that a low-temperature first-order phase transition may be destroyed for increasing values of {sigma}, similarly to what happens in the compound Fe{sub x}Mg{sub 1-x}Cl{sub 2}, whose finite-temperature first-order phase transition is presumably destroyed by an increase in the field randomness.

  14. Evolution of order and chaos across a first-order quantum phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Leviatan, A., E-mail: ami@phys.huji.ac.il [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Macek, M., E-mail: mmacek@phys.huji.ac.il [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)

    2012-07-24

    We study the evolution of the dynamics across a generic first-order quantum phase transition in an interacting boson model of nuclei. The dynamics inside the phase coexistence region exhibits a very simple pattern. A classical analysis reveals a robustly regular dynamics confined to the deformed region and well separated from a chaotic dynamics ascribed to the spherical region. A quantum analysis discloses regular bands of states in the deformed region, which persist to energies well above the phase-separating barrier, in the face of a complicated environment. The impact of kinetic collective rotational terms on this intricate interplay of order and chaos is investigated.

  15. Evolution of order and chaos across a first-order quantum phase transition

    CERN Document Server

    Leviatan, A

    2012-01-01

    We study the evolution of the dynamics across a generic first order quantum phase transition in an interacting boson model of nuclei. The dynamics inside the phase coexistence region exhibits a very simple pattern. A classical analysis reveals a robustly regular dynamics confined to the deformed region and well separated from a chaotic dynamics ascribed to the spherical region. A quantum analysis discloses regular bands of states in the deformed region, which persist to energies well above the phase-separating barrier, in the face of a complicated environment. The impact of kinetic collective rotational terms on this intricate interplay of order and chaos is investigated.

  16. Self-Organized Bistability Associated with First-Order Phase Transitions

    Science.gov (United States)

    di Santo, Serena; Burioni, Raffaella; Vezzani, Alessandro; Muñoz, Miguel A.

    2016-06-01

    Self-organized criticality elucidates the conditions under which physical and biological systems tune themselves to the edge of a second-order phase transition, with scale invariance. Motivated by the empirical observation of bimodal distributions of activity in neuroscience and other fields, we propose and analyze a theory for the self-organization to the point of phase coexistence in systems exhibiting a first-order phase transition. It explains the emergence of regular avalanches with attributes of scale invariance that coexist with huge anomalous ones, with realizations in many fields.

  17. Dynamic Off-Equilibrium Transition in Systems Slowly Driven across Thermal First-Order Phase Transitions

    Science.gov (United States)

    Pelissetto, Andrea; Vicari, Ettore

    2017-01-01

    We study the off-equilibrium behavior of systems with short-range interactions, slowly driven across a thermal first-order transition, where the equilibrium dynamics is exponentially slow. We consider a dynamics that starts in the high-T phase at time t =ti0 in the low-T phase, with a time-dependent temperature T (t )/Tc≈1 -t /ts, where ts is the protocol time scale. A general off-equilibrium scaling (OS) behavior emerges in the limit of large ts. We check it at the first-order transition of the two-dimensional q -state Potts model with q =20 and 10. The numerical results show evidence of a dynamic transition, where the OS functions show a spinodal-like singularity. Therefore, the general mean-field picture valid for systems with long-range interactions is qualitatively recovered, provided the time dependence is appropriately (logarithmically) rescaled.

  18. The gravitational waves from the first-order phase transition with a dimension-six operator

    Science.gov (United States)

    Cai, Rong-Gen; Sasaki, Misao; Wang, Shao-Jiang

    2017-08-01

    We investigate in details the gravitational wave (GW) from the first-order phase transition (PT) in the extended standard model of particle physics with a dimension-six operator, which is capable of exhibiting the recently discovered slow first-order PT in addition to the usually studied fast first-order PT. To simplify the discussion, it is sufficient to work with an example of a toy model with the sextic term, and we propose an unified description for both slow and fast first-order PTs. We next study the full one-loop effective potential of the model with fixed/running renormalization-group (RG) scales. Compared to the prediction of GW energy density spectrum from the fixed RG scale, we find that the presence of running RG scale could amplify the peak amplitude by amount of one order of magnitude while shift the peak frequency to the lower frequency regime, and the promising regime of detection within the sensitivity ranges of various space-based GW detectors shrinks down to a lower cut-off value of the sextic term rather than the previous expectation.

  19. Phase conversion in a weakly first-order quark-hadron transition

    CERN Document Server

    Bessa, A; Mintz, B W

    2008-01-01

    We investigate the process of phase conversion in a thermally-driven {\\it weakly} first-order quark-hadron transition. This scenario is physically appealing even if the nature of this transition in equilibrium proves to be a smooth crossover for vanishing baryonic chemical potential. We construct an effective potential by combining the equation of state obtained within Lattice QCD for the partonic sector with that of a gas of resonances in the hadronic phase, and present numerical results on bubble profiles, nucleation rates and time evolution, including the effects from reheating on the dynamics for different expansion scenarios. Our findings confirm the standard picture of a cosmological first-order transition, in which the process of phase conversion is entirely dominated by nucleation, also in the case of a weakly first-order transition. On the other hand, we show that, even for expansion rates much lower than those expected in high-energy heavy ion collisions, nucleation is very unlikely, indicating that...

  20. Discovering a First-Order Phase Transition in the Li-CeO2 System.

    Science.gov (United States)

    Li, Kaikai; Zhou, Xiaoye; Nie, Anmin; Sun, Sheng; He, Yan-Bing; Ren, Wei; Li, Baohua; Kang, Feiyu; Kim, Jang-Kyo; Zhang, Tong-Yi

    2017-02-08

    An in-depth understanding of (de)lithiation induced phase transition in electrode materials is crucial to grasp their structure-property relationships and provide guidance to the design of more desirable electrodes. By operando synchrotron XRD (SXRD) measurement and Density Functional Theory (DFT) based calculations, we discover a reversible first-order phase transition for the first time during (de)lithiation of CeO2 nanoparticles. The LixCeO2 compound phase is identified to possess the same fluorite crystal structure with FM3M space group as that of the pristine CeO2 nanoparticles. The SXRD determined lattice constant of the LixCeO2 compound phase is 0.551 nm, larger than that of 0.541 nm of the pristine CeO2 phase. The DFT calculations further reveal that the Li induced redistribution of electrons causes the increase in the Ce-O covalent bonding, the shuffling of Ce and O atoms, and the jump expansion of lattice constant, thereby resulting in the first-order phase transition. Discovering the new phase transition throws light upon the reaction between lithium and CeO2, and provides opportunities to the further investigation of properties and potential applications of LixCeO2.

  1. First-Order Transitions and the Magnetic Phase Diagram of CeSb

    DEFF Research Database (Denmark)

    Lebech, Bente; Clausen, Kurt Nørgaard; Vogt, O.

    1980-01-01

    The high-temperature (14-17K) low-magnetic field (0-0.8 T) region of the phase diagram of the anomalous antiferromagnet CeSb has been reinvestigated by neutron diffraction in an attempt to locate a possible tricritical point. Previous neutron diffraction studies indicated that a tricritical point...... might exist in the magnetic phase diagram of CeSb at 16K for a field of approximately 0.3 T. The present study concludes that the transitions from the paramagnetic to the magnetically ordered states are of first order for fields below 0.8 T. Within the experimental accuracy no change has been observed...

  2. Anomalous critical slowdown at a first order phase transition in single polymer chains

    Science.gov (United States)

    Zhang, Shuangshuang; Qi, Shuanhu; Klushin, Leonid I.; Skvortsov, Alexander M.; Yan, Dadong; Schmid, Friederike

    2017-08-01

    Using Brownian dynamics, we study the dynamical behavior of a polymer grafted onto an adhesive surface close to the mechanically induced adsorption-stretching transition. Even though the transition is first order (in the infinite chain length limit, the stretching degree of the chain jumps discontinuously), the characteristic relaxation time is found to grow according to a power law as the transition point is approached. We present a dynamic effective interface model which reproduces these observations and provides an excellent quantitative description of the simulation data. The generic nature of the theoretical model suggests that the unconventional mixing of features that are characteristic for first-order transitions (a jump in an order parameter) and features that are characteristic of critical points (an anomalous slowdown) may be a common phenomenon in force-driven phase transitions of macromolecules.

  3. Gravitational wave signals of electroweak phase transition triggered by dark matter

    Science.gov (United States)

    Chao, Wei; Guo, Huai-Ke; Shu, Jing

    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.

  4. First-order phase transitions in spin-glass models with multiple paramagnetic solutions

    Energy Technology Data Exchange (ETDEWEB)

    Lozza, H.F. [Departamento de Fisica, FCEyN, Universidad de Buenos Aires, Pab. I, Ciudad Universitaria - (1428) Buenos Aires (Argentina)]. E-mail: homero@df.uba.ar

    2004-12-31

    The paramagnetic and the one-step replica-symmetry-breaking spin-glass solutions of a p-spin-glass model in the presence of a transverse field are studied in the neighborhood of the phase transition curve. Two qualitatively different regions are found in the phase diagram. For a transition temperature higher than a certain value Tc, the thermodynamic transition is of second order, otherwise it is of first order with latent heat. The temperature Tc is joined to a point in the phase diagram where a transition between two paramagnetic solutions happens. A discussion about the order of the thermodynamic-phase transition in the quantum random orthogonal model is presented.

  5. First-order phase transitions in spin-glass models with multiple paramagnetic solutions

    Science.gov (United States)

    Lozza, H. F.

    2004-12-01

    The paramagnetic and the one-step replica-symmetry-breaking spin-glass solutions of a p-spin-glass model in the presence of a transverse field are studied in the neighborhood of the phase transition curve. Two qualitatively different regions are found in the phase diagram. For a transition temperature higher than a certain value Tc, the thermodynamic transition is of second order, otherwise it is of first order with latent heat. The temperature Tc is joined to a point in the phase diagram where a transition between two paramagnetic solutions happens. A discussion about the order of the thermodynamic-phase transition in the quantum random orthogonal model is presented.

  6. Gravitational Waves from the Sound of a First Order Phase Transition

    Science.gov (United States)

    Hindmarsh, Mark; Huber, Stephan J.; Rummukainen, Kari; Weir, David J.

    2014-01-01

    We report on the first three-dimensional numerical simulations of first-order phase transitions in the early Universe to include the cosmic fluid as well as the scalar field order parameter. We calculate the gravitational wave (GW) spectrum resulting from the nucleation, expansion, and collision of bubbles of the low-temperature phase, for phase transition strengths and bubble wall velocities covering many cases of interest. We find that the compression waves in the fluid continue to be a source of GWs long after the bubbles have merged, a new effect not taken properly into account in previous modeling of the GW source. For a wide range of models, the main source of the GWs produced by a phase transition is, therefore, the sound the bubbles make.

  7. Order, Chaos and Quasi Symmetries in a First-Order Quantum Phase Transition

    CERN Document Server

    Leviatan, A

    2014-01-01

    We study the competing order and chaos in a first-order quantum phase transition with a high barrier. The boson model Hamiltonian employed, interpolates between its U(5) (spherical) and SU(3) (deformed) limits. A classical analysis reveals regular (chaotic) dynamics at low (higher) energy in the spherical region, coexisting with a robustly regular dynamics in the deformed region. A quantum analysis discloses, amidst a complicated environment, persisting regular multiplets of states associated with partial U(5) and quasi SU(3) dynamical symmetries.

  8. Polarization Switching in Ferroelectric Thin Films Undergoing First-Order Phase Transitions

    Directory of Open Access Journals (Sweden)

    L. A. Bakaleinikov

    2010-01-01

    Full Text Available The main switching properties in ferroelectrics undergoing first-order phase transitions are simulated within the framework of the extended Ishibashi dipole-lattice model including the dipole-dipole interaction in a two-dimensional case for ferroelectric nanoscale objects. The peculiarities of the temperature dependence of the switching rate and the pyroelectric coefficient are discussed in the range of coexistence of the metastable states. The used coefficients of the long-range and short-range interactions between the dipoles are taken from the dielectric and structure measurements in BaTiO3.

  9. No First-Order Phase Transition in the Gross-Neveu Model?

    CERN Document Server

    Brzoska, A; Brzoska, Andrej; Thies, Michael

    2002-01-01

    Within a variational calculation we investigate the role of baryons for the structure of dense matter in the Gross-Neveu model. We construct a trial ground state at finite baryon density which breaks translational invariance. Its scalar potential interpolates between widely spaced kinks and antikinks at low density and the value zero at infinite density. Its energy is lower than the one of the standard Fermi gas at all densities considered. This suggests that the discrete gamma_5 symmetry of the Gross-Neveu model does not get restored in a first order phase transition at finite density, at variance with common wisdom.

  10. Renormalization-group theory for cooling first-order phase transitions in Potts models.

    Science.gov (United States)

    Liang, Ning; Zhong, Fan

    2017-03-01

    We develop a dynamic field-theoretic renormalization-group (RG) theory for cooling first-order phase transitions in the Potts model. It is suggested that the well-known imaginary fixed points of the q-state Potts model for q>10/3 in the RG theory are the origin of the dynamic scaling found recently from numerical simulations, apart from logarithmic corrections. This indicates that the real and imaginary fixed points of the Potts model are both physical and control the scalings of the continuous and discontinuous phase transitions, respectively, of the model. Our one-loop results for the scaling exponents are already not far away from the numerical results. Further, the scaling exponents depend on q only slightly, consistent with the numerical results. Therefore, the theory is believed to provide a natural explanation of the dynamic scaling including the scaling exponents and their scaling laws for various observables in the cooling first-order phase transition of the Potts model.

  11. Renormalization-group theory for cooling first-order phase transitions in Potts models

    Science.gov (United States)

    Liang, Ning; Zhong, Fan

    2017-03-01

    We develop a dynamic field-theoretic renormalization-group (RG) theory for cooling first-order phase transitions in the Potts model. It is suggested that the well-known imaginary fixed points of the q -state Potts model for q >10 /3 in the RG theory are the origin of the dynamic scaling found recently from numerical simulations, apart from logarithmic corrections. This indicates that the real and imaginary fixed points of the Potts model are both physical and control the scalings of the continuous and discontinuous phase transitions, respectively, of the model. Our one-loop results for the scaling exponents are already not far away from the numerical results. Further, the scaling exponents depend on q only slightly, consistent with the numerical results. Therefore, the theory is believed to provide a natural explanation of the dynamic scaling including the scaling exponents and their scaling laws for various observables in the cooling first-order phase transition of the Potts model.

  12. Gravitational waves from the sound of a first order phase transition

    CERN Document Server

    Hindmarsh, Mark; Rummukainen, Kari; Weir, David J

    2014-01-01

    We report on the first 3-dimensional numerical simulations of first-order phase transitions in the early universe to include the cosmic fluid as well as the scalar field order parameter. We calculate the gravitational wave (GW) spectrum resulting from the nucleation, expansion and collision of bubbles of the low-temperature phase, paying particular attention to those sourced by the fluid. We find that the fluid continues to be a source of GWs long after the bubbles have merged, a new effect not taken into account in previous modelling of the GW source based on the envelope approximation. The kinetic energy of the fluid is in the form of compression waves: the main source of the GWs after a phase transition is therefore the sound the bubbles make.

  13. Arguing on entropic and enthalpic first-order phase transitions in strongly interacting matter

    CERN Document Server

    Wunderlich, Falk; Kampfer, Burkhard

    2016-01-01

    The pattern of isentropes in the vicinity of a first-order phase transition is proposed as a key for a sub-classification. While the confinement--deconfinement transition, conjectured to set in beyond a critical end point in the QCD phase diagram, is often related to an entropic transition and the apparently settled gas-liquid transition in nuclear matter is an enthalphic transition, the conceivable local isentropes w.r.t.\\ "incoming" or "outgoing" serve as another useful guide for discussing possible implications, both in the presumed hydrodynamical expansion stage of heavy-ion collisions and the core-collapse of supernova explosions. Examples, such as the quark-meson model and two-phase models, are shown to distinguish concisely the different transitions.

  14. The first order phase-transition of polycrystal solid surfaces with nanothickness

    Institute of Scientific and Technical Information of China (English)

    Y.A. Minaev

    2006-01-01

    The fundamental equations of thermodynamics of a film have been used for describing a fundamental property of solid crystalline materials i.e. the first-order phase transition on the grain boundaries by the formation of two-dimensional liquid. The generalized equation that is obtained is used for calculating the premelting temperature of any metal, which has a value in the range of 0.55-0.86 of the melting point. The experimental diffusion coefficient of nitrogen in steel at premelting temperature is the same as in the liquid phase. The described phenomenon of phase transition on the grain boundaries decreases in case of radical modification of the existing process engineering of handling metals. It also provides a precise physical explanation to the super plasticity of fine-structure metal alloys.

  15. The electroweak phase transition in minimal supergravity models

    CERN Document Server

    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...

  16. First-order superconducting phase transition in CeCoIn5.

    Science.gov (United States)

    Bianchi, A; Movshovich, R; Oeschler, N; Gegenwart, P; Steglich, F; Thompson, J D; Pagliuso, P G; Sarrao, J L

    2002-09-23

    The superconducting phase transition in heavy fermion CeCoIn5 (T(c)=2.3 K in zero field) becomes first order when the magnetic field H parallel [001] is greater than 4.7 T, and the transition temperature is below T0 approximately 0.31T(c). The change from second order at lower fields is reflected in strong sharpening of both specific heat and thermal expansion anomalies associated with the phase transition, a strong magnetocaloric effect, and a steplike change in the sample volume. This effect is due to Pauli limiting in a type-II superconductor, and was predicted theoretically in the mid-1960s.

  17. First order phase transition in the height of a meniscus in a tapered capillary

    Science.gov (United States)

    Pettersen, Michael; Rolley, Etienne

    2008-03-01

    When a fluid rises in a capillary of non-uniform cross section, additional terms arise in the balance of capillary forces, compared to the case of a capillary of uniform cross section, due to the changing area of the meniscus. Recently, it has been pointed out that this can lead to a first order phase transition, resulting in a discontinuous jump in the equilibrium position of the meniscus. We present the results of an experiment using isopropanol and silicone oil in cones with apex upwards of different opening angles. The cone is slowly lowered into the liquid using a translation stage. We have measured the capillary rise in this geometry, and observed the predicted phase transition.

  18. First-order phase transitions in spinor Bose gases and frustrated magnets

    Science.gov (United States)

    Debelhoir, T.; Dupuis, N.

    2016-11-01

    We show that phase transitions in spin-1 Bose gases and stacked triangular Heisenberg antiferromagnets—an example of frustrated magnets with competing interactions—are described by the same Landau-Ginzburg-Wilson Hamiltonian with O (3 )×O (2 ) symmetry. In agreement with previous nonperturbative-renormalization-group studies of the three-dimensional O (3 )×O (2 ) model, we find that the transition from the normal phase to the superfluid ferromagnetic phase in a spin-1 Bose gas is weakly first order and shows pseudoscaling behavior. The (nonuniversal) pseudoscaling exponent ν is fully determined by the scattering lengths a0 and a2. We provide estimates of ν in 87Rb,41K, and 7Li atom gases which can be tested experimentally. We argue that pseudoscaling comes from either a crossover phenomenon due to proximity of the O(6) Wilson-Fisher fixed point (87Rb and 41K) or the existence of two unphysical fixed points (with complex coordinates) which slow down the RG flow (7Li). These unphysical fixed points are a remnant of the chiral and antichiral fixed points that exist in the O (N )×O (2 ) model when N is larger than Nc≃5.3 (the transition being then second order and controlled by the chiral fixed point). Finally, we discuss a O (2 )×O (2 ) lattice model and show that our results, even though we find the transition to be first order, are compatible with Monte Carlo simulations yielding an apparent second-order transition.

  19. Dark Matter and Strong Electroweak Phase Transition in a Radiative Neutrino Mass Model

    CERN Document Server

    Ahriche, Amine

    2013-01-01

    We consider an extension of the standard model (SM) with charged singlet scalars and right handed (RH) neutrinos all at the electroweak scale. In this model, the neutrino masses are generated at three loops, which provide an explanation for their smallness, and the lightest RH neutrino, $N_{1}$, is a dark matter candidate. We find that for three generations of RH neutrinos, the model can be consistent with the neutrino oscillation data, lepton flavor violating processes, $N_{1}$ can have a relic density in agreement with the recent Planck data, and the electroweak phase transition can be strongly first order. We also show that the charged scalars may enhance the branching ratio $h-->YY$, where as $h-->YZ$ get can get few percent suppression. We also discuss the phenomenological implications of the RH neutrinos at the collider.

  20. Numerical tests of the electroweak phase transition and thermodynamics of the electroweak plasma

    CERN Document Server

    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.

  1. Gregarious versus individualistic behavior in Vicsek swarms and the onset of first-order phase transitions

    Science.gov (United States)

    Baglietto, Gabriel; Albano, Ezequiel V.; Candia, Julián

    2013-08-01

    The standard Vicsek model (SVM) is a minimal non-equilibrium model of self-propelled particles that appears to capture the essential ingredients of critical flocking phenomena. In the SVM, particles tend to align with each other and form ordered flocks of collective motion; however, perturbations controlled by a noise term lead to a noise-driven continuous order-disorder phase transition. In this work, we extend the SVM by introducing a parameter α that allows particles to be individualistic instead of gregarious, i.e. to choose a direction of motion independently of their neighbors. By focusing on the small-noise regime, we show that a relatively small probability of individualistic motion (around 10%) is sufficient to drive the system from a Vicsek-like ordered phase to a disordered phase. Despite the fact that the α-extended model preserves the O(n) symmetry and the interaction range, as well as the dimensionality of the underlying SVM, this novel phase transition is found to be discontinuous (first order), an intriguing manifestation of the richness of the non-equilibrium flocking/swarming phenomenon.

  2. The magnetocaloric effect at the first-order magneto-elastic phase transition.

    Science.gov (United States)

    Basso, Vittorio

    2011-06-08

    This paper presents a study of the magnetocaloric effect at the first-order magneto-elastic phase transition. The entropy change Δs at the transition temperature is given by the sum of the magnetic and the structural contributions. By using a thermodynamic model, it is shown that the sign and amplitude of the structural contribution to Δs are determined by the dimensionless parameter ζ (zeta) which depends on β, the steepness of the change of exchange forces with volume, and on α(p), the thermal expansion coefficient of the structural lattice. For ζ magnetocaloric effect. For 0 1 the structural entropy dominates and a transition occurs upon heating from a low temperature paramagnet to a high temperature ferromagnet.

  3. Critical dynamical properties of a first-order dissipative phase transition

    Science.gov (United States)

    Casteels, W.; Fazio, R.; Ciuti, C.

    2017-01-01

    We theoretically investigate the critical properties of a single driven-dissipative nonlinear photon mode. In a well-defined thermodynamical limit of large excitation numbers, the exact quantum solution describes a first-order phase transition in the regime where semiclassical theory predicts optical bistability. We study the behavior of the complex spectral gap associated with the Liouvillian superoperator of the corresponding master equation. We show that in this limit the Liouvillian gap vanishes exponentially and that the bimodality of the photon Wigner function disappears. The connection between the considered thermodynamical limit of large photon numbers for the single-mode cavity and the thermodynamical limit of many cavities for a driven-dissipative Bose-Hubbard system is discussed.

  4. First-order phase transitions in repulsive rigid k-mers on two-dimensional lattices

    Science.gov (United States)

    Pasinetti, P. M.; Romá, F.; Ramirez-Pastor, A. J.

    2012-02-01

    In a previous paper [F. Romá, A. J. Ramirez-Pastor, and J. L. Riccardo, Phys. Rev. B 72, 035444 (2005)], the critical behavior of repulsive rigid rods of length k (k-mers) on a square lattice at half coverage has been studied by using Monte Carlo (MC) simulations. The obtained results indicated that (1) the phase transition occurring in the system is a second-order phase transition for all adsorbate sizes k; and (2) the universality class of the transition changes from 2D Ising-type for monomers (k = 1) to an unknown universality class for k ≥ 2. In the present work, we revisit our previous results together with further numerical evidences, resulting from new extensive MC simulations based on an efficient exchange algorithm and using high-performance computational capabilities. In contrast to our previous conclusions (1) and (2), the new numerical calculations clearly support the occurrence of a first-order phase transition for k ≥ 2. In addition, a similar scenario was found for k-mers adsorbed on the triangular lattice at coverage k/(2k+1).

  5. First Order Phase Transition of Plaquette Ordering in SU(4) Antiferromagnets

    Science.gov (United States)

    Mishra, Anup; Ma, Michael; Zhang, Fu-Chun

    2002-03-01

    Spin systems with orbital degeneracy may have an ideal limit with SU(4) degeneracy(Phys. Rev. Lett 81,3527 (1998)). Based on MFT and variational calculations, it was proposed that the ground state of the SU(4) system in 2D is a spin and orbital liquid. Finite-sized numerical calculations on square lattice further support this proposition(Eur. Phys. J. B17,367 (2000)). The numerical work also suggests the ground state to be 4-fold degenerate. We propose that the 4-fold degeneracy is due to spontaneous formation of plaquettes with alternating plaquettes of strong and weak correlations. Using fermion MFT on square and triangular lattice, we find at zero temperature that the ground state is a state of disconnected plaquettes. The discrete symmetry of plaquette ordering allows for a finite temperature phase transition from the disordered phase to the ordered phase even in 2D. Within MFT, the transition is found to be first order for both the square and triangular lattice. Nevertheless, there are important differences between the transitions on the two lattices.

  6. First-order phase transition during displacement of amphiphilic biomacromolecules from interfaces by surfactant molecules.

    Science.gov (United States)

    Ettelaie, Rammile; Dickinson, Eric; Pugnaloni, Luis

    2014-11-19

    The adsorption of surfactants onto a hydrophobic interface, already laden with a fixed number of amphiphilic macromolecules, is studied using the self consistent field calculation method of Scheutjens and Fleer. For biopolymers having unfavourable interactions with the surfactant molecules, the adsorption isotherms show an abrupt jump at a certain value of surfactant bulk concentration. Alternatively, the same behaviour is exhibited when the number of amphiphilic chains on the interface is decreased. We show that this sudden jump is associated with a first-order phase transition, by calculating the free energy values for the stable and the metastable states at both sides of the transition point. We also observe that the transition can occur for two approaching surfaces, from a high surfactant coverage phase to a low surfactant coverage one, at sufficiently close separation distances. The consequence of this finding for the steric colloidal interactions, induced by the overlap of two biopolymer + surfactant films, is explored. In particular, a significantly different interaction, in terms of its magnitude and range, is predicted for these two phases. We also consider the relevance of the current study to problems involving the competitive displacement of proteins by surfactants in food colloid systems.

  7. Euclidean Dynamical Triangulation revisited: is the phase transition really first order?

    CERN Document Server

    Rindlisbacher, Tobias

    2014-01-01

    The transition between the two phases of 4D Euclidean Dynamical Triangulation [1] was long believed to be of second order until in 1996 first order behavior was found for sufficiently large systems [3,4]. However, one may wonder if this finding was affected by the numerical methods used: to control volume fluctuations, in both studies [3,4] an artificial harmonic potential was added to the action; in [4] measurements were taken after a fixed number of accepted instead of attempted moves which introduces an additional error. Finally the simulations suffer from strong critical slowing down which may have been underestimated. In the present work, we address the above weaknesses: we allow the volume to fluctuate freely within a fixed interval; we take measurements after a fixed number of attempted moves; and we overcome critical slowing down by using an optimized parallel tempering algorithm [6]. With these improved methods, on systems of size up to 64k 4-simplices, we confirm that the phase transition is first o...

  8. The Emergence of Life as a First-Order Phase Transition

    Science.gov (United States)

    Mathis, Cole; Bhattacharya, Tanmoy; Imari Walker, Sara

    2017-03-01

    It is well known that life on Earth alters its environment over evolutionary and geological timescales. An important open question is whether this is a result of evolutionary optimization or a universal feature of life. In the latter case, the origin of life would be coincident with a shift in environmental conditions. Here we present a model for the emergence of life in which replicators are explicitly coupled to their environment through the recycling of a finite supply of resources. The model exhibits a dynamic, first-order phase transition from nonlife to life, where the life phase is distinguished by selection on replicators. We show that environmental coupling plays an important role in the dynamics of the transition. The transition corresponds to a redistribution of matter in replicators and their environment, driven by selection on replicators, exhibiting an explosive growth in diversity as replicators are selected. The transition is accurately tracked by the mutual information shared between replicators and their environment. In the absence of successfully repartitioning system resources, the transition fails to complete, leading to the possibility of many frustrated trials before life first emerges. Often, the replicators that initiate the transition are not those that are ultimately selected. The results are consistent with the view that life's propensity to shape its environment is indeed a universal feature of replicators, characteristic of the transition from nonlife to life. We discuss the implications of these results for understanding life's emergence and evolutionary transitions more broadly.

  9. First-order quantum phase transitions: test ground for emergent chaoticity, regularity and persisting symmetries

    CERN Document Server

    Macek, M

    2014-01-01

    We present a comprehensive analysis of the emerging order and chaos and enduring symmetries, accompanying a generic (high-barrier) first-order quantum phase transition (QPT). The interacting boson model Hamiltonian employed, describes a QPT between spherical and deformed shapes, associated with its U(5) and SU(3) dynamical symmetry limits. A~classical analysis of the intrinsic dynamics reveals a rich but simply-divided phase space structure with a H\\'enon-Heiles type of chaotic dynamics ascribed to the spherical minimum and a robustly regular dynamics ascribed to the deformed minimum. The simple pattern of mixed but well-separated dynamics persists in the coexistence region and traces the crossing of the two minima in the Landau potential. A quantum analysis discloses a number of regular low-energy U(5)-like multiplets in the spherical region, and regular SU(3)-like rotational bands extending to high energies and angular momenta, in the deformed region. These two kinds of regular subsets of states retain thei...

  10. First-order quantum phase transitions: Test ground for emergent chaoticity, regularity and persisting symmetries

    Energy Technology Data Exchange (ETDEWEB)

    Macek, M., E-mail: mmacek@Racah.phys.huji.ac.il; Leviatan, A., E-mail: ami@phys.huji.ac.il

    2014-12-15

    We present a comprehensive analysis of the emerging order and chaos and enduring symmetries, accompanying a generic (high-barrier) first-order quantum phase transition (QPT). The interacting boson model Hamiltonian employed, describes a QPT between spherical and deformed shapes, associated with its U(5) and SU(3) dynamical symmetry limits. A classical analysis of the intrinsic dynamics reveals a rich but simply-divided phase space structure with a Hénon–Heiles type of chaotic dynamics ascribed to the spherical minimum and a robustly regular dynamics ascribed to the deformed minimum. The simple pattern of mixed but well-separated dynamics persists in the coexistence region and traces the crossing of the two minima in the Landau potential. A quantum analysis discloses a number of regular low-energy U(5)-like multiplets in the spherical region, and regular SU(3)-like rotational bands extending to high energies and angular momenta, in the deformed region. These two kinds of regular subsets of states retain their identity amidst a complicated environment of other states and both occur in the coexistence region. A symmetry analysis of their wave functions shows that they are associated with partial U(5) dynamical symmetry (PDS) and SU(3) quasi-dynamical symmetry (QDS), respectively. The pattern of mixed but well-separated dynamics and the PDS or QDS characterization of the remaining regularity, appear to be robust throughout the QPT. Effects of kinetic collective rotational terms, which may disrupt this simple pattern, are considered.

  11. Numerical simulations of acoustically generated gravitational waves at a first order phase transition

    CERN Document Server

    Hindmarsh, Mark; Rummukainen, Kari; Weir, David J

    2015-01-01

    We present details of numerical simulations of the gravitational radiation produced by a first order {thermal} phase transition in the early universe. We confirm that the dominant source of gravitational waves is sound waves generated by the expanding bubbles of the low-temperature phase. We demonstrate that the sound waves have a power spectrum with power-law form between the scales set by the average bubble separation (which sets the length scale of the fluid flow $L_\\text{f}$) and the bubble wall width. The sound waves generate gravitational waves whose power spectrum also has a power-law form, at a rate proportional to $L_\\text{f}$ and the square of the fluid kinetic energy density. We identify a dimensionless parameter $\\tilde\\Omega_\\text{GW}$ characterising the efficiency of this "acoustic" gravitational wave production whose value is $8\\pi\\tilde\\Omega_\\text{GW} \\simeq 0.8 \\pm 0.1$ across all our simulations. We compare the acoustic gravitational waves with the standard prediction from the envelope appr...

  12. Statistical mechanics of random geometric graphs: Geometry-induced first-order phase transition.

    Science.gov (United States)

    Ostilli, Massimo; Bianconi, Ginestra

    2015-04-01

    Random geometric graphs (RGGs) can be formalized as hidden-variables models where the hidden variables are the coordinates of the nodes. Here we develop a general approach to extract the typical configurations of a generic hidden-variables model and apply the resulting equations to RGGs. For any RGG, defined through a rigid or a soft geometric rule, the method reduces to a nontrivial satisfaction problem: Given N nodes, a domain D, and a desired average connectivity 〈k〉, find, if any, the distribution of nodes having support in D and average connectivity 〈k〉. We find out that, in the thermodynamic limit, nodes are either uniformly distributed or highly condensed in a small region, the two regimes being separated by a first-order phase transition characterized by a O(N) jump of 〈k〉. Other intermediate values of 〈k〉 correspond to very rare graph realizations. The phase transition is observed as a function of a parameter a∈[0,1] that tunes the underlying geometry. In particular, a=1 indicates a rigid geometry where only close nodes are connected, while a=0 indicates a rigid antigeometry where only distant nodes are connected. Consistently, when a=1/2 there is no geometry and no phase transition. After discussing the numerical analysis, we provide a combinatorial argument to fully explain the mechanism inducing this phase transition and recognize it as an easy-hard-easy transition. Our result shows that, in general, ad hoc optimized networks can hardly be designed, unless to rely to specific heterogeneous constructions, not necessarily scale free.

  13. First-order inflation

    Energy Technology Data Exchange (ETDEWEB)

    Kolb, E.W. (Fermi National Accelerator Lab., Batavia, IL (USA) Chicago Univ., IL (USA). Enrico Fermi Inst.)

    1990-09-01

    In the original proposal, inflation occurred in the process of a strongly first-order phase transition. This model was soon demonstrated to be fatally flawed. Subsequent models for inflation involved phase transitions that were second-order, or perhaps weakly first-order; some even involved no phase transition at all. Recently the possibility of inflation during a strongly first-order phase transition has been revived. In this talk I will discuss some models for first-order inflation, and emphasize unique signatures that result in inflation is realized in a first-order transition. Before discussing first-order inflation, I will briefly review some of the history of inflation to demonstrate how first-order inflation differs from other models. 58 refs., 3 figs.

  14. Probing the nature of electroweak phase transition from particle colliders to gravitational wave detection

    CERN Document Server

    Huang, Fa Peng; Wang, Dong-Gang; Cai, Yi-Fu; Zhang, Xinmin

    2016-01-01

    In this letter, we explore the nature of the electroweak phase transition with both the particle colliders and the gravitational wave (GW) detection. With the observed Higgs mass, the shape of the Higgs potential is fully determined in the standard model of particle physics, however, it could be physically different. Working with the effective field theory, we will show the Higgs potential with a sextic term of the Higgs field included could give the 125 GeV Higgs mass , but a different Higgs potential. Furthermore, this Higgs scenario can produce a strong first order phase transition for the electroweak baryogenesis, and interestingly predict new physics in the Higgs sector, which can be tested at colliders such as the Large Hadron Collider (LHC) and the planning Circular Electron Positron Collider (CEPC). And we will also point out this strong first order phase transition will lead to a detectable GW signal for the GW interferometers , such as eLISA, DECIGO and BBO. Our study in this letter on the electrowe...

  15. Singlet-Catalyzed Electroweak Phase Transitions in the 100 TeV Frontier

    CERN Document Server

    Kotwal, Ashutosh V; No, Jose Miguel; Winslow, Peter

    2016-01-01

    We study the prospects for probing a gauge singlet scalar-driven strong first order electroweak phase transition with a future proton-proton collider in the 100 TeV range. Singlet-Higgs mixing enables resonantly-enhanced di-Higgs production, potentially aiding discovery prospects. We perform Monte Carlo scans of the parameter space to identify regions associated with a strong first-order electroweak phase transition, analyze the corresponding di-Higgs signal, and select a set of benchmark points that span the range of di-Higgs signal strengths. For the $b\\bar{b}\\gamma\\gamma$ and $4\\tau$ final states, we investigate discovery prospects for each benchmark point for the high luminosity phase of the Large Hadron Collider and for a future $pp$ collider with $\\sqrt{s}$ = 50, 100, or 200 TeV. We find that any of these future collider scenarios could significantly extend the reach beyond that of the high luminosity LHC, and that with $\\sqrt{s}$ = 100 TeV (200 TeV) and 30 ab$^{-1}$, the full region of parameter space ...

  16. Polarization induced water molecule dissociation below the first-order electronic-phase transition temperature.

    Science.gov (United States)

    Das Arulsamy, Andrew; Kregar, Zlatko; Eleršič, Kristina; Modic, Martina; Subramani, Uma Shankar

    2011-09-01

    Hydrogen produced from the photocatalytic splitting of water is one of the reliable alternatives to replace the polluting fossil and the radioactive nuclear fuels. Here, we provide unequivocal evidence for the existence of blue- and red-shifting O-H covalent bonds within a single water molecule adsorbed on the MgO surface as a result of asymmetric displacement polarizabilities. The adsorbed H-O-H on MgO gives rise to one weaker H-O bond, while the other O-H covalent bond from the same adsorbed water molecule compensates this effect with a stronger bond. The weaker bond (nearest to the surface), the interlayer tunneling electrons and the silver substrate are shown to be the causes for the smallest dissociative activation energy on the MgO monolayer. The origin that is responsible to initiate the splitting mechanism is proven to be due to the changes in the polarizability of an adsorbed water molecule, which are further supported by the temperature-dependent static dielectric constant measurements for water below the first-order electronic-phase transition temperature.

  17. Vortex-Antivortex Pair Production in a First Order Phase Transition

    CERN Document Server

    Digal, S; Srivastava, A M; Digal, Sanatan; Sengupta, Supratim; Srivastava, Ajit M.

    1997-01-01

    We carry out numerical simulation of a first order phase transition in 2+1 dimensions by randomly nucleating bubbles, and study the formation of global U(1) vortices. Bubbles grow and coalesce and vortices are formed at junctions of bubbles via standard Kibble mechanism as well as due to a new mechanism, recently proposed by us, where defect-antidefect pairs are produced due to field oscillations. We make a comparative study of the contribution of both of these mechanisms for vortex production. We find that, for high nucleation rate of bubbles, vortex-antivortex pairs produced via the new mechanism have overlapping configurations, and annihilate quickly; so only those vortices survive till late which are produced via the Kibble mechanism. However, for low nucleation rates, bubble collisions are energetic enough to lead to many well separated vortex-antivortex pairs being produced via the new mechanism. For example, in a simulation involving nucleation of 20 bubbles, a total of 14 non-overlapping vortices and ...

  18. Analytical First-Order Molecular Properties and Forces within the Adiabatic Connection Random Phase Approximation.

    Science.gov (United States)

    Burow, Asbjörn M; Bates, Jefferson E; Furche, Filipp; Eshuis, Henk

    2014-01-14

    The random phase approximation (RPA) is an increasingly popular method for computing molecular ground-state correlation energies within the adiabatic connection fluctuation-dissipation theorem framework of density functional theory. We present an efficient analytical implementation of first-order RPA molecular properties and nuclear forces using the resolution-of-the-identity (RI) approximation and imaginary frequency integration. The centerpiece of our approach is a variational RPA energy Lagrangian invariant under unitary transformations of occupied and virtual reference orbitals, respectively. Its construction requires the solution of a single coupled-perturbed Kohn-Sham equation independent of the number of perturbations. Energy gradients with respect to nuclear displacements and other first-order properties such as one-particle densities or dipole moments are obtained from partial derivatives of the Lagrangian. Our RPA energy gradient implementation exhibits the same [Formula: see text] scaling with system size N as a single-point RPA energy calculation. In typical applications, the cost for computing the entire gradient vector with respect to nuclear displacements is ∼5 times that of a single-point RPA energy calculation. Derivatives of the quadrature nodes and weights used for frequency integration are essential for RPA gradients with an accuracy consistent with RPA energies and can be included in our approach. The quality of RPA equilibrium structures is assessed by comparison to accurate theoretical and experimental data for covalent main group compounds, weakly bonded dimers, and transition metal complexes. RPA outperforms semilocal functionals as well as second-order Møller-Plesset (MP2) theory, which fails badly for the transition metal compounds. Dipole moments of polarizable molecules and weakly bound dimers show a similar trend. RPA harmonic vibrational frequencies are nearly of coupled cluster singles, doubles, and perturbative triples quality

  19. Dynamical scaling for underdamped strain order parameters quenched below first-order phase transitions

    Science.gov (United States)

    Shankaraiah, N.; Dubey, Awadhesh K.; Puri, Sanjay; Shenoy, Subodh R.

    2016-12-01

    In the conceptual framework of phase ordering after temperature quenches below transition, we consider the underdamped Bales-Gooding-type "momentum conserving" dynamics of a 2D martensitic structural transition from a square-to-rectangle unit cell. The one-component or NOP=1 order parameter is one of the physical strains, and the Landau free energy has a triple well, describing a first-order transition. We numerically study the evolution of the strain-strain correlation, and find that it exhibits dynamical scaling, with a coarsening length L (t ) ˜tα . We find at intermediate and long times that the coarsening exponent sequentially takes on respective values close to α =2 /3 and 1 /2 . For deep quenches, the coarsening can be arrested at long times, with α ≃0 . These exponents are also found in 3D. To understand such behavior, we insert a dynamical-scaling ansatz into the correlation function dynamics to give, at a dominant scaled separation, a nonlinear kinetics of the curvature g (t )≡1 /L (t ) . The curvature solutions have time windows of power-law decays g ˜1 /tα , with exponent values α matching simulations, and manifestly independent of spatial dimension. Applying this curvature-kinetics method to mass-conserving Cahn-Hilliard dynamics for a double-well Landau potential in a scalar NOP=1 order parameter yields exponents α =1 /4 and 1 /3 for intermediate and long times. For vector order parameters with NOP≥2 , the exponents are α =1 /4 only, consistent with previous work. The curvature kinetics method could be useful in extracting coarsening exponents for other phase-ordering dynamics.

  20. Can large fermion chemical potentials suppress the electroweak phase transition ?

    CERN Document Server

    Quimbay, C; Hurtado, R; Quimbay, Carlos; Morales, John; Hurtado, Rafael

    2000-01-01

    We calculate the critical temperature $(T_c$) of the electroweak phase transition in the minimal standard model considering simultaneously temperature ($T$) and fermion chemical potential ($\\mu_f$) effects over the effective potential. The calculation is performed in the one-loop approximation to the effective potential at non-zero temperature using the real time formalism of the thermal field theory. We show that it exists a fermion chemical potential critical value ($\\mu_f^c$) for which the Higgs boson condensate vanishes at T=0. If $T$ and $\\mu_f$ effects are considered simultaneously, it is shown that for $\\mu_f \\geq \\mu_f^c$ then $T_c^2 \\leq 0$, implying that the electroweak phase transition might not take place.

  1. Quantum adiabatic algorithm and scaling of gaps at first-order quantum phase transitions.

    Science.gov (United States)

    Laumann, C R; Moessner, R; Scardicchio, A; Sondhi, S L

    2012-07-20

    Motivated by the quantum adiabatic algorithm (QAA), we consider the scaling of the Hamiltonian gap at quantum first-order transitions, generally expected to be exponentially small in the size of the system. However, we show that a quantum antiferromagnetic Ising chain in a staggered field can exhibit a first-order transition with only an algebraically small gap. In addition, we construct a simple classical translationally invariant one-dimensional Hamiltonian containing nearest-neighbor interactions only, which exhibits an exponential gap at a thermodynamic quantum first-order transition of essentially topological origin. This establishes that (i) the QAA can be successful even across first-order transitions but also that (ii) it can fail on exceedingly simple problems readily solved by inspection, or by classical annealing.

  2. Electroweak Phase Transitions in left-right symmetric models

    CERN Document Server

    Barenboim, G; Barenboim, Gabriela; Rius, Nuria

    1998-01-01

    We study the finite-temperature effective potential of minimal left-right symmetric models containing a bidoublet and two triplets in the scalar sector. We perform a numerical analysis of the parameter space compatible We perform a numerical analysis of the parameter space compatible with the requirement that baryon asymmetry is not washed out by sphaleron processes after the electroweak phase transition. We find that the spectrum of scalar particles for these acceptable cases is consistent with present experimental bounds.

  3. Classical and quantum Reissner-Nordström black hole thermodynamics and first order phase transition

    Science.gov (United States)

    Ghaffarnejad, Hossein

    2016-01-01

    First we consider classical Reissner-Nordström black hole (CRNBH) metric which is obtained by solving Einstein-Maxwell metric equation for a point electric charge e inside of a spherical static body with mass M. It has 2 interior and exterior horizons. Using Bekenstein-Hawking entropy theorem we calculate interior and exterior entropy, temperature, Gibbs free energy and heat capacity at constant electric charge. We calculate first derivative of the Gibbs free energy with respect to temperature which become a singular function having a singularity at critical point Mc=2|e|/√{3} with corresponding temperature Tc=1/24π√{3|e|}. Hence we claim first order phase transition is happened there. Temperature same as Gibbs free energy takes absolutely positive (negative) values on the exterior (interior) horizon. The Gibbs free energy takes two different positive values synchronously for 0< T< Tc but not for negative values which means the system is made from two subsystem. For negative temperatures entropy reaches to zero value at Tto-∞ and so takes Bose-Einstein condensation single state. Entropy increases monotonically in case 0< T< Tc. Regarding results of the work presented at Wang and Huang (Phys. Rev. D 63:124014, 2001) we calculate again the mentioned thermodynamical variables for remnant stable final state of evaporating quantum Reissner-Nordström black hole (QRNBH) and obtained results same as one in case of the CRNBH. Finally, we solve mass loss equation of QRNBH against advance Eddington-Finkelstein time coordinate and derive luminosity function. We obtain switching off of QRNBH evaporation before than the mass completely vanishes. It reaches to a could Lukewarm type of RN black hole which its final remnant mass is m_{final}=|e| in geometrical units. Its temperature and luminosity vanish but not in Schwarzschild case of evaporation. Our calculations can be take some acceptable statements about information loss paradox (ILP).

  4. First-Order-Like Phase Transition Induced by Two Different Kinds of Noise in Dispersive Optical Bistability

    Institute of Scientific and Technical Information of China (English)

    HEYing; ZHUShi-Qun

    2003-01-01

    With unified colored noise approximation, the steady state distribution function in dispersive optical bistability including both intensity and phase fluctuations is obtained. The parameter plane of the first-order-like phase transition is a/so derived with numerical method. It is found that the number of extremes at non-zero values of the output field in the steady state distribution function is changed from zero, two to four. It is shown that the strengths of the intensity fluctuation and the phase fluctuation have great effect on the first-order-fike phase transition.

  5. Triaxial-Stress-Induced Homogeneous Hysteresis-Free First-Order Phase Transformations with Stable Intermediate Phases

    Science.gov (United States)

    Levitas, Valery I.; Chen, Hao; Xiong, Liming

    2017-01-01

    Starting with thermodynamic predictions and following with molecular dynamics simulations, special triaxial compression-tension states were found for which the stresses for the instability of the crystal lattice of silicon (Si) are the same for direct and reverse phase transformations (PTs) between semiconducting Si I and metallic Si II phases. This leads to unique homogeneous and hysteresis-free first-order PTs, for which each intermediate crystal lattice along the transformation path is in indifferent thermodynamic equilibrium and can be arrested and studied by fixing the strain in one direction. By approaching these stress states, a traditional two-phase system continuously transforms to homogenous intermediate phases. Zero hysteresis and homogeneous transformations are the optimal property for various PT applications, which drastically reduce damage and energy dissipation.

  6. Fluctuation effects in first-order phase transitions: Theory and model for martensitic transformations

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Mouritsen, Ole G.

    1990-01-01

    -dimensional Monte Carlo simulation, showing clear precursor phenomena near the first-order transition and spontaneous nucleation. The kinetics of the domain growth is studied and found to be exceedingly slow. The results are applicable for martensitic transformations and structural surface...

  7. Holography and the Electroweak Phase Transition

    CERN Document Server

    Creminelli, P; 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.

  8. First-Order-Like Phase Transition Induced by Two Different Kinds of Noise in Dispersive Optical Bistability

    Institute of Scientific and Technical Information of China (English)

    HE Ying; ZHU Shi-Qun

    2003-01-01

    With unified colored noise approximation, the steady state distribution function in dispersive opticalbistability including both intensity and phase fluctuations is obtained. The parameter plane of the first-order-like phasetransition is also derived with numerical method. It is found that the number of extremes at non-zero values of theoutput field in the steady state distribution function is changed from zero, two to four. It is shown that the strengths of the intensity fluctuation and the phase fluctuation have great effect on the first-order-like phase transition.

  9. Coexistence of order and chaos at critical points of first-order quantum phase transitions in nuclei

    CERN Document Server

    Macek, M

    2011-01-01

    We study the interplay between ordered and chaotic dynamics at the critical point of a generic first-order quantum phase transition in the interacting boson model of nuclei. Classical and quantum analyses reveal a distinct behavior of the coexisting phases. While the dynamics in the deformed phase is robustly regular, the spherical phase shows strongly chaotic behavior in the same energy intervals. The effect of collective rotations on the dynamics is investigated.

  10. Particle number scale invariant feature of the states around the critical point of the first order nuclear shape phase transition

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We study systematically the evolutive behaviors of some energy ratios,E2 transition rate ratios and isomer shift in the nuclear shape phase transitions.We find that the quantities sensitive to the phase transition and independent of free parameter(s) are approximately particle number N scale invariant around the critical point of the first order phase transition,similar to that in the second order phase transition.

  11. Particle number scale invariant feature of the states around the critical point of the first order nuclear shape phase transition

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu; HOU ZhanFeng; LIU YuXin

    2009-01-01

    We study systematically the evolutive behaviors of some energy ratios,E2 transition rate ratios and Isomer shift in the nuclear shape phase transitions.We find that the quantities sensitive to the phase transition and independent of free parameter(s) are approximately particle number N scale invariant around the critical point of the first order phase transition,similar to that in the second order phase transition.

  12. Finite size scaling and first-order phase transition in a modified XY model

    Science.gov (United States)

    Sinha, Suman; Roy, Soumen Kumar

    2010-02-01

    Monte Carlo simulation has been performed in a two-dimensional modified XY -model first proposed by Domany [Phys. Rev. Lett. 52, 1535 (1984)] The cluster algorithm of Wolff has been used and multiple histogram reweighting is performed. The first-order scaling behavior of the quantities such as specific heat and free-energy barrier are found to be obeyed accurately. While the lowest-order correlation function was found to decay to zero at long distance just above the transition, the next-higher-order correlation function shows a nonzero plateau.

  13. First-order quasi-phase-matched blue light generation in surface-poled Ti:indiffused lithium niobate waveguides

    CERN Document Server

    Busacca, Alessandro C; Eason, Robert W; Mailis, Sakellaris; 10.1063/1.1758776

    2012-01-01

    We demonstrate efficient first-order quasi-phase-matched second-harmonic generation in a surface periodically poled Ti:indiffused lithium niobate waveguide; 6 mW of continuous-wave blue radiation (wavelength = 412.6 nm) was produced showing the potential of surface domain inversion for efficient nonlinear waveguide interactions.

  14. A Preisach approach to modeling partial phase transitions in the first order magnetocaloric material MnFe(P,As)

    DEFF Research Database (Denmark)

    von Moos, Lars; Bahl, C.R.H.; Nielsen, Kaspar Kirstein;

    2014-01-01

    . Such materials are potential candidates for application in magnetic refrigeration devices. However, the first order materials often have adverse properties such as hysteresis, making actual performance troublesome to quantify, a subject not thoroughly studied within this field.Here we investigate the behavior...... of MnFe(P,As) under partial phase transitions, which is similar to what materials experience in actual magnetic refrigeration devices. Partial phase transition curves, in the absence of a magnetic field, are measured using calorimetry and the experimental results are compared to simulations......Magnetic refrigeration is an emerging technology that could provide energy efficient and environmentally friendly cooling. Magnetocaloric materials in which a structural phase transition is found concurrently with the magnetic phase transition are often termed first order magnetocaloric materials...

  15. Gravitational waves from first order phase transitions as a probe of an early matter domination era and its inverse problem

    Energy Technology Data Exchange (ETDEWEB)

    Barenboim, Gabriela, E-mail: Gabriela.Barenboim@uv.es; Park, Wan-Il, E-mail: Wanil.Park@uv.es

    2016-08-10

    We investigate the gravitational wave background from a first order phase transition in a matter-dominated universe, and show that it has a unique feature from which important information about the properties of the phase transition and thermal history of the universe can be easily extracted. Also, we discuss the inverse problem of such a gravitational wave background in view of the degeneracy among macroscopic parameters governing the signal.

  16. Magnetization dynamics across the first order phase transition in FeRh thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pressacco, Federico

    2014-08-01

    The metallic alloy FeRh undergoes a phase transition from an antiferromagnetic phase (AFP) to a ferromagnetic phase (FP) when heated above 400 K. The change in magnetic order results in a change in the net magnetization of the system from zero up to 1.2 kA/m after increasing the system temperature. This is an uncommon characteristic for a magnetic material since usually one observes a decrease of the magnetization upon heating. This discloses the possibility to apply FeRh to Heat-Assisted Magnetic Recording (HAMR) devices.

  17. Full correspondence between asymmetric filling of slits and first-order phase transition lines

    Directory of Open Access Journals (Sweden)

    Leszek Szybisz

    2011-12-01

    Full Text Available Adsorption on single planar walls and filling of slits with identical planar walls are investigated in the frame of the density functional theory. In this sort of slits the external potential is symmetric with respect to its central plane. Calculations were carried out by applying both the canonical and grand canonical ensembles (CE and GCE, respectively. The behavior is analyzed by varying the strength of the adsorbate-substrate attraction, the temperature T, and the coverage Γℓ. Results obtained for physisorption of Xe on alkaline surfaces are reported in the present work. Prewetting (PW lines and wetting temperatures, Tw, are determined from the analysis of adsorption on single walls. The filling of slits is analyzed for temperatures T > Tw. It is found that whenever for a given Xe-substrate combination the adsorption on a single wall exhibits a first-order wetting transition then asymmetric profiles that break the left-right symmetry of the external potential appear in the filling of an equivalent slit. These spontaneously symmetry breaking (SSB solutions occur in a restricted range of Γℓ with a T-dependent width. In the case of closed slits analyzed in the CE scheme, the obtained asymmetric profiles exhibit lower Helmholtz free energies than the symmetric species and, therefore, could be stabilized in this geometry. For open slits, the GCE scheme yields all the symmetric and SSB states in the corresponding convex regimes of the free energy. It is shown that both the CE and the GCE frames yield three coexistent states, two symmetric and one asymmetric twofold degenerate. Both a PW line and the related SSB effect terminate at the same temperature. For rather strongly attractive surfaces reentrant SSB states are found at a fixed value of T.

  18. Full correspondence between asymmetric filling of slits and first-order phase transition lines

    Science.gov (United States)

    Szybisz, Leszek; Sartarelli, Salvador A.

    2011-12-01

    Adsorption on single planar walls and filling of slits with identical planar walls are investigated in the frame of the density functional theory. In this sort of slits the external potential is symmetric with respect to its central plane. Calculations were carried out by applying both the canonical and grand canonical ensembles (CE and GCE, respectively). The behavior is analyzed by varying the strength of the adsorbate-substrate attraction, the temperature T, and the coverage Γℓ. Results obtained for physisorption of Xe on alkaline surfaces are reported in the present work. Prewetting (PW) lines and wetting temperatures, Tw, are determined from the analysis of adsorption on single walls. The filling of slits is analyzed for temperatures T > Tw. It is found that whenever for a given Xe-substrate combination the adsorption on a single wall exhibits a first-order wetting transition then asymmetric profiles that break the left-right symmetry of the external potential appear in the filling of an equivalent slit. These spontaneously symmetry breaking (SSB) solutions occur in a restricted range of Γℓ with a T-dependent width. In the case of closed slits analyzed in the CE scheme, the obtained asymmetric profiles exhibit lower Helmholtz free energies than the symmetric species and, therefore, could be stabilized in this geometry. For open slits, the GCE scheme yields all the symmetric and SSB states in the corresponding convex regimes of the free energy. It is shown that both the CE and the GCE frames yield three coexistent states, two symmetric and one asymmetric twofold degenerate. Both a PW line and the related SSB effect terminate at the same temperature. For rather strongly attractive surfaces reentrant SSB states are found at a fixed value of T.

  19. Second-Order Catalytic Quasispecies Yields First-Order Phase Transition

    OpenAIRE

    Wagner, Nathaniel; Tannenbaum, Emmanuel; Ashkenasy, Gonen

    2009-01-01

    The quasispecies model describes processes related to the origin of life and viral evolutionary dynamics. We discuss how the error catastrophe that reflects the transition from localized to delocalized quasispecies population is affected by catalytic replication of different reaction orders. Specifically, we find that 2nd order mechanisms lead to 1st order discontinuous phase transitions in the viable population fraction, and conclude that the "higher" the interaction the "lower" the transiti...

  20. Rate-induced solubility and suppression of the first-order phase transition in olivine LiFePO4.

    Science.gov (United States)

    Zhang, Xiaoyu; van Hulzen, Martijn; Singh, Deepak P; Brownrigg, Alex; Wright, Jonathan P; van Dijk, Niels H; Wagemaker, Marnix

    2014-05-14

    The impact of ultrahigh (dis)charge rates on the phase transition mechanism in LiFePO4 Li-ion electrodes is revealed by in situ synchrotron diffraction. At high rates the solubility limits in both phases increase dramatically, causing a fraction of the electrode to bypass the first-order phase transition. The small transforming fraction demonstrates that nucleation rates are consequently not limiting the transformation rate. In combination with the small fraction of the electrode that transforms at high rates, this indicates that higher performances may be achieved by further optimizing the ionic/electronic transport in LiFePO4 electrodes.

  1. Interplay of order and chaos across a first-order quantum shape-phase transition in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Leviatan, A.; Macek, M. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)

    2012-10-20

    We study the nature of the dynamics in a first-order quantum phase transition between spherical and prolate-deformed nuclear shapes. Classical and quantum analyses reveal a change in the system from a chaotic Henon-Heiles behavior on the spherical side into a pronounced regular dynamics on the deformed side. Both order and chaos persist in the coexistence region and their interplay reflects the Landau potential landscape and the impact of collective rotations.

  2. Interplay of order and chaos across a first-order quantum shape-phase transition in nuclei

    CERN Document Server

    Leviatan, A

    2012-01-01

    We study the nature of the dynamics in a first-order quantum phase transition between spherical and prolate-deformed nuclear shapes. Classical and quantum analyses reveal a change in the system from a chaotic H\\'enon-Heiles behavior on the spherical side into a pronounced regular dynamics on the deformed side. Both order and chaos persist in the coexistence region and their interplay reflects the Landau potential landscape and the impact of collective rotations.

  3. First order phase transition in finite density QCD using the modulus of the Dirac determinant

    CERN Document Server

    Aloisio, R; Di Carlo, G; Galante, A; Grillo, A F

    1998-01-01

    We report results of simulations of strong coupling, finite density QCD obtained within a MFA inspired approach where the fermion determinant in the integration measure is replaced by its absolute value. Contrary to the standard wisdom, we show that within this approach a clear signal of a phase transition appears with a critical chemical potential in extremely good agreement with the results obtained with the Glasgow algorithm. The modulus of the fermion determinant seems therefore to preserve some of the relevant physical properties of the system. We also analyze the dependence of our results on the quark mass, including both the chiral and large mass limit, and the theory in the quenched approximation.

  4. Electroweak Phase Transition in the MSSM 4-Dimensional Lattice Simulations

    CERN Document Server

    Csikor, Ferenc; Hegedüs, P; Jakovác, A; Katz, S D; Piróth, A

    2000-01-01

    Recent lattice results have shown that there is no Standard Model (SM) electroweak phase transition (EWPT) for Higgs boson masses above \\approx 72 GeV, which is below the present experimental limit. According to perturbation theory and 3-dimensional (3d) lattice simulations there could be an EWPT in the Minimal Supersymmetric Standard Model (MSSM) that is strong enough for baryogenesis up to m_h \\approx 105 GeV. In this letter we present the results of our large scale 4-dimensional (4d) lattice simulations for the MSSM EWPT. We carried out infinite volume and continuum limit extrapolations, which show a somewhat weaker transition than suggested by 3d simulations. The upper bound of the lightest Higgs boson mass for a MSSM baryogenesis scenario is m_h = 97 +/- 4 GeV. We determined the properties of the bubble wall that are important for a successful baryogenesis.

  5. Clustering of neural code words revealed by a first-order phase transition

    Science.gov (United States)

    Huang, Haiping; Toyoizumi, Taro

    2016-06-01

    A network of neurons in the central nervous system collectively represents information by its spiking activity states. Typically observed states, i.e., code words, occupy only a limited portion of the state space due to constraints imposed by network interactions. Geometrical organization of code words in the state space, critical for neural information processing, is poorly understood due to its high dimensionality. Here, we explore the organization of neural code words using retinal data by computing the entropy of code words as a function of Hamming distance from a particular reference codeword. Specifically, we report that the retinal code words in the state space are divided into multiple distinct clusters separated by entropy-gaps, and that this structure is shared with well-known associative memory networks in a recallable phase. Our analysis also elucidates a special nature of the all-silent state. The all-silent state is surrounded by the densest cluster of code words and located within a reachable distance from most code words. This code-word space structure quantitatively predicts typical deviation of a state-trajectory from its initial state. Altogether, our findings reveal a non-trivial heterogeneous structure of the code-word space that shapes information representation in a biological network.

  6. Quantum decoherence of subcritical bubble in electroweak phase transition

    CERN Document Server

    Shiromizu, T

    1995-01-01

    In a weakly first order phase transition the typical scale of a subcritical bubble calculated in our previous papers turned out to be too small. At this scale quantum fluctuations may dominate and our previous classical result may be altered. So we examine the critical size of a subcritical bubble where quantum-to-classical transition occurs through quantum decoherence. We show that this critical size is almost equal to the typical scale which we previously obtained.

  7. Possible existence of two amorphous phases of D-mannitol related by a first-order transition

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Men; Yu, Lian, E-mail: lian.yu@wisc.edu [Department of Chemistry and School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States); Wang, Jun-Qiang; Perepezko, John H. [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2015-06-28

    We report that the common polyalcohol D-mannitol may have two amorphous phases related by a first-order transition. Slightly above its glass transition temperature T{sub g} (284 K), the supercooled liquid (SCL) of D-mannitol transforms to a low-energy, apparently amorphous phase with stronger hydrogen bonds. The enthalpy of this so-called Phase X is approximately halfway between those of the known amorphous and crystalline phases, a position low for glass aging and high for crystal polymorphs. Similar to the SCL, Phase X is transparent with broad X-ray diffraction and Raman scattering; upon temperature cycling, it exhibits a glass-transition-like change of heat capacity. On fast heating, Phase X transforms back to the SCL near T{sub g} + 50 K, enabling a determination of their equilibrium temperature. The presence of D-sorbitol as a plasticizer enables observation of a first-order transition from the SCL to Phase X entirely in the liquid state (liquid-liquid transition). The transition from D-mannitol’s SCL to Phase X has intriguing similarities with the formation of the glacial phase of triphenyl phosphite (TPP) and the conversion from high-density to low-density amorphous ice, both studied intensely in the context of polyamorphism. All three processes occur near T{sub g} with substantial enthalpy decrease toward the crystalline phases; the processes in water and D-mannitol both strengthen the hydrogen bonds. In contrast to TPP, D-mannitol’s Phase X forms more rapidly and can transform back to the SCL. These features make D-mannitol a valuable new model for understanding polyamorphism.

  8. Flow of hypermagnetic helicity in the embryo of a new phase in the electroweak phase transition

    CERN Document Server

    Akhmet'ev, P M; Sokoloff, D D

    2010-01-01

    The dynamics of the magnetic helicity during the electroweak phase transition in the early Universe is studied. It is shown that the boundary surface between symmetric (hypermagnetic) phase and Maxwellian phase with a broken symmetry is a membrana for the separation of the magnetic helicity. Assuming the total linking number of knots of hypermagnetic field is negative, it is proved that the helicity rising in the Maxwellian phase is left-handed.

  9. Gravity Waves Seeded by Turbulence and Magnetic Fields From a First Order Phase Transition With Non-Renormalizable Electroweak Vacua

    CERN Document Server

    Poltis, Robert

    2012-01-01

    It is widely believed that the standard model is a low energy effective theory which may have higher dimensional non-renormalizable operators. The existence of these new operators can lead to interesting dynamics for the evolution of the universe, including the appearance of new vacuum states. If the universe today exists in a false vacuum, there will be a non-zero probability to tunnel to the true vacuum state of the universe. Should this transition occur elsewhere in the universe, bubbles of true vacuum will nucleate and expand outwards. Bubbles that nucleate in the hot dense plasma of the early universe will feel a friction from the plasma that acts against the expansion of the bubble, until the bubble eventually reaches a steady state expansion. Unlike many bubble formation scenarios where the bubble wall velocity rapidly approaches the speed of light, friction from the hot primordial plasma can cause the expanding bubble wall to reach a terminal velocity while gravity waves are free to propagate through ...

  10. Gravitational Waves from Phase Transitions at the Electroweak Scale and Beyond

    CERN Document Server

    Grojean, Christophe; Grojean, Christophe; Servant, Geraldine

    2007-01-01

    If there was a first order phase transition in the early universe, there should be an associated stochastic background of gravitational waves. In this paper, we point out that the characteristic frequency of the spectrum due to phase transitions which took place in the temperature range 100 GeV - 10^7 GeV is precisely in the window that will be probed by the second generation of space-based interferometers such as the Big Bang Observer (BBO). Taking into account the astrophysical foreground, we determine the type of phase transitions which could be detected either at LISA, LIGO or BBO, in terms of the amount of supercooling and the duration of the phase transition that are needed. Those two quantities can be calculated for any given effective scalar potential describing the phase transition. In particular, the new models of electroweak symmetry breaking which have been proposed in the last few years typically have a different Higgs potential from the Standard Model. They could lead to a gravitational wave sig...

  11. Neutron diffraction evidence for kinetic arrest of first order magneto-structural phase transitions in some functional magnetic materials.

    Science.gov (United States)

    Siruguri, V; Babu, P D; Kaushik, S D; Biswas, Aniruddha; Sarkar, S K; Krishnan, Madangopal; Chaddah, P

    2013-12-11

    Neutron diffraction measurements, performed in the presence of an external magnetic field, have been used to show structural evidence for the kinetic arrest of the first order phase transition from (i) the high temperature austenite phase to the low temperature martensite phase in the magnetic shape memory alloy Ni37Co11Mn42.5Sn9.5, (ii) the higher temperature ferromagnetic phase to the lower temperature antiferromagnetic phase in the half-doped charge ordered compound La0.5Ca0.5MnO3 and (iii) the formation of glass-like arrested states in both compounds. The cooling and heating under unequal fields protocol has been used to establish phase coexistence of metastable and equilibrium states, and also to demonstrate the devitrification of the arrested metastable states in the neutron diffraction patterns. We also explore the field–temperature dependent kinetic arrest line TK(H), through the transformation of the arrested phase to the equilibrium phase. This transformation has been observed isothermally in reducing H, as also on warming in constant H. TK is seen to increase as H increases in both cases, consistent with the low-T equilibrium phase having lower magnetization.

  12. Why does shear banding behave like first-order phase transitions? Derivation of a potential from a mechanical constitutive model.

    Science.gov (United States)

    Sato, K; Yuan, X-F; Kawakatsu, T

    2010-02-01

    Numerous numerical and experimental evidence suggest that shear banding behavior looks like first-order phase transitions. In this paper, we demonstrate that this correspondence is actually established in the so-called non-local diffusive Johnson-Segalman model (the DJS model), a typical mechanical constitutive model that has been widely used for describing shear banding phenomena. In the neighborhood of the critical point, we apply the reduction procedure based on the center manifold theory to the governing equations of the DJS model. As a result, we obtain a time evolution equation of the flow field that is equivalent to the time-dependent Ginzburg-Landau (TDGL) equations for modeling thermodynamic first-order phase transitions. This result, for the first time, provides a mathematical proof that there is an analogy between the mechanical instability and thermodynamic phase transition at least in the vicinity of the critical point of the shear banding of DJS model. Within this framework, we can clearly distinguish the metastable branch in the stress-strain rate curve around the shear banding region from the globally stable branch. A simple extension of this analysis to a class of more general constitutive models is also discussed. Numerical simulations for the original DJS model and the reduced TDGL equation is performed to confirm the range of validity of our reduction theory.

  13. Theory of the dynamics of first-order phase transitions: unstable fixed points, exponents, and dynamical scaling.

    Science.gov (United States)

    Zhong, Fan; Chen, Qizhou

    2005-10-21

    Phase transitions are of great importance in a diversity of fields. They are usually classified into continuous phase transitions and first-order phase transitions (FOPTs). Whereas the former has a well-developed theoretical framework of the renormalization-group (RG) theory, no general theory has yet been developed for the latter that appear far more frequently. Focusing on the dynamics of a generic FOPT in the phi4 model below its critical point, we show by a field-theoretic RG method that it is governed by an unexpected unstable fixed point of the corresponding phi3 model. Accordingly, it exhibits a distinct scaling and universality behavior with unstable exponents different from the critical ones.

  14. Third Law of Thermodynamics and The Shape of the Phase Diagram for Systems With a First-Order Quantum Phase Transition.

    Science.gov (United States)

    Kirkpatrick, T R; Belitz, D

    2015-07-10

    The third law of thermodynamics constrains the phase diagram of systems with a first-order quantum phase transition. For a zero conjugate field, the coexistence curve has an infinite slope at T=0. If a tricritical point exists at T>0, then the associated tricritical wings are perpendicular to the T=0 plane, but not to the zero-field plane. These results are based on the third law and basic thermodynamics only, and are completely general. As an explicit example we consider the ferromagnetic quantum phase transition in clean metals, where a first-order quantum phase transition is commonly observed.

  15. Phase Behavior of Diblock Copolymer–Homopolymer Ternary Blends: Congruent First-Order Lamellar–Disorder Transition

    Energy Technology Data Exchange (ETDEWEB)

    Hickey, Robert J.; Gillard, Timothy M.; Irwin, Matthew T.; Morse, David C.; Lodge, Timothy P.; Bates, Frank S. (UMM)

    2016-10-13

    We have established the existence of a line of congruent first-order lamellar-to-disorder (LAM–DIS) transitions when appropriate amounts of poly(cyclohexylethylene) (C) and poly(ethylene) (E) homopolymers are mixed with a corresponding compositionally symmetric CE diblock copolymer. The line of congruent transitions, or the congruent isopleth, terminates at the bicontinuous microemulsion (BμE) channel, and its trajectory appears to be influenced by the critical composition of the C/E binary homopolymer blend. Blends satisfying congruency undergo a direct LAM–DIS transition without passing through a two-phase region. We present complementary optical transmission, small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and dynamic mechanical spectroscopy (DMS) results that establish the phase behavior at constant copolymer volume fraction and varying C/E homopolymer volume ratios. Adjacent to the congruent composition at constant copolymer volume fraction, the lamellar and disordered phases are separated by two-phase coexistence windows, which converge, along with the line of congruent transitions, at an overall composition in the phase prism coincident with the BμE channel. Hexagonal and cubic (double gyroid) phases occur at higher diblock copolymer concentrations for asymmetric amounts of C and E homopolymers. These results establish a quantitative method for identifying the detailed phase behavior of ternary diblock copolymer–homopolymer blends, especially in the vicinity of the BμE.

  16. The Widom-Rowlinson mixture on a sphere: elimination of exponential slowing down at first-order phase transitions.

    Science.gov (United States)

    Fischer, T; Vink, R L C

    2010-03-17

    Computer simulations of first-order phase transitions using 'standard' toroidal boundary conditions are generally hampered by exponential slowing down. This is partly due to interface formation, and partly due to shape transitions. The latter occur when droplets become large such that they self-interact through the periodic boundaries. On a spherical simulation topology, however, shape transitions are absent. We expect that by using an appropriate bias function, exponential slowing down can be largely eliminated. In this work, these ideas are applied to the two-dimensional Widom-Rowlinson mixture confined to the surface of a sphere. Indeed, on the sphere, we find that the number of Monte Carlo steps needed to sample a first-order phase transition does not increase exponentially with system size, but rather as a power law τ α V(α), with α≈2.5, and V the system area. This is remarkably close to a random walk for which α(RW) = 2. The benefit of this improved scaling behavior for biased sampling methods, such as the Wang-Landau algorithm, is investigated in detail.

  17. Sound shell model for acoustic gravitational wave production at a first-order phase transition in the early Universe

    CERN Document Server

    Hindmarsh, Mark

    2016-01-01

    A model for the acoustic production of gravitational waves at a first order phase transition is presented. The source of gravitational radiation is the sound waves generated by the explosive growth of bubbles of the stable phase. The model assumes that the sound waves are linear and that their power spectrum is determined by the characteristic form of the sound shell around the expanding bubble. The predicted power spectrum has two length scales, the average bubble separation and the sound shell width when the bubbles collide. The peak of the power spectrum is at wavenumbers set by the sound shell width. For higher wavenumber $k$, the power spectrum decreases as $k^{-3}$. At wavenumbers below the inverse bubble separation, the power spectrum goes as $k^5$. For bubble wall speeds near the speed of sound where these two length scales are distinguished, there is an intermediate $k^{1}$ power law. The detailed dependence of the power spectrum on the wall speed and the other parameters of the phase transition rais...

  18. The phase transition of the first order in the critical region of the gas-liquid system

    Directory of Open Access Journals (Sweden)

    I.R. Yukhnovskii

    2014-12-01

    Full Text Available This is a summarising investigation of the events of the phase transition of the first order that occur in the critical region below the liquid-gas critical point. The grand partition function has been completely integrated in the phase-space of the collective variables. The basic density measure is the quartic one. It has the form of the exponent function with the first, second, third and fourth degree of the collective variables. The problem has been reduced to the Ising model in an external field, the role of which is played by the generalised chemical potential μ*. The line μ*(η =0, where η is the density, is the line of the phase transition. We consider the isothermal compression of the gas till the point where the phase transition on the line μ*(η =0 is reached. When the path of the pressing reaches the line μ* =0 in the gas medium, a droplet of liquid springs up. The work for its formation is obtained, the surface-tension energy is calculated. On the line μ* =0 we have a two-phase system: the gas and the liquid (the droplet one. The equality of the gas and of the liquid chemical potentials is proved. The process of pressing is going on. But the pressure inside the system has stopped, two fixed densities have arisen: one for the gas-phase ηG=ηc(1-d/2 and the other for the liquid-phase ηL=ηc(1+d/2 (symmetrically to the rectlinear diameter, where ηc=0.13044 is the critical density. Starting from that moment the external pressure works as a latent work of pressure. Its value is obtained. As a result, the gas-phase disappears and the whole system turns into liquid. The jump of the density is equal to ηc d, where d=(D/2G1/2 ~ τν/2. D and G are coefficients of the Hamiltonian in the last cell connected with the renormalisation-group symmetry. The equation of state is written.

  19. Positive magnetoresistance and large magnetostriction at first-order antiferro ferromagnetic phase transitions in RMn2Si2 compounds

    Science.gov (United States)

    Gerasimov, E. G.; Mushnikov, N. V.; Koyama, K.; Kanomata, T.; Watanabe, K.

    2008-11-01

    The magnetostriction and magnetoresistance associated with the field-induced and spontaneous first-order antiferro-ferromagnetic (AF-F) phase transitions have been studied for quasi-single-crystalline samples of La0.25Sm0.75Mn2Si2, La0.25Y0.75Mn2Si2 and La0.27Y0.73Mn2Si2 compounds with natural layered ThCr2Si2-type structure. It was found that both the spontaneous and field-induced AF-F transitions are accompanied by a large volume magnetostriction ΔV/V≈2 × 10-3 and anisotropic linear changes of the lattice parameters Δa/a≈1.6 × 10-3, Δc/c≈-0.75 × 10-3. The field-induced AF-F magnetic phase transition has been observed in magnetic fields applied both along the c-axis and in the basal plane, and the magnetostriction value is virtually independent of the direction of applied field. It has been found also that the magnetoresistance is positive in these compounds (the value of the electrical resistance in the ferromagnetic state is higher than that in the antiferromagnetic state) for the fields applied both along the c-axis and in the basal plane. The value of the magnetoresistance observed along the c-axis is 30 times as high as that in the basal plane. The obtained results indicate that the electronic band structure changes are likely responsible for the AF-F magnetic phase transitions observed in the RMn2X2 compounds.

  20. Electroweak baryogenesis and low energy supersymmetry

    CERN Document Server

    Carena, M S; Riotto, Antonio; Vilja, I; Wagner, C E M

    1997-01-01

    Electroweak baryogenesis is an interesting theoretical scenario, which demands physics beyond the Standard Model at energy scales of the order of the weak boson masses. It has been recently emphasized that, in the presence of light stops, the electroweak phase transition can be strongly first order, opening the window for electroweak baryogenesis in the MSSM. For the realization of this scenario, the Higgs boson must be light, at the reach of the LEP2 collider. In this article, we compute the baryon asymmetry assuming the presence of non-trivial CP violating phases in the parameters associated with the left-right stop mixing term and the Higgsino mass $\\mu$. We conclude that a phase $|\\sin \\phi_{\\mu}| > 0.01$ and Higgsino and gaugino mass parameters $|\\mu| \\simeq M_2$, and of the order of the electroweak scale, are necessary in order to generate the observed baryon asymmetry.

  1. Itinerant ferromagnetism, phase separation and first-order paramagnetic metal to antiferromagnetic insulator transitions—novel insights to the frustrated Hubbard model

    Science.gov (United States)

    Zitzler, R.; Pruschke, Th.; Bulla, R.

    2004-05-01

    We discuss the magnetic phase diagram for the Hubbard model with magnetic frustration obtained within the dynamical mean-field theory. Most interesting is the appearance of a first-order paramagnetic metal to antiferromagnetic insulator transition for the magnetically frustrated lattice at half filling. For finite doping the antiferromagnetic phase is susceptible to phase separation and competes with an itinerant ferromagnetic phase (Nagaoka ferromagnetism), leading to an unexpectedly rich magnetic phase diagram.

  2. Itinerant ferromagnetism, phase separation and first-order paramagnetic metal to antiferromagnetic insulator transitions--novel insights to the frustrated Hubbard model

    Energy Technology Data Exchange (ETDEWEB)

    Zitzler, R.; Pruschke, Th. E-mail: pruschke@theorie.physik.uni-goettingen.de; Bulla, R

    2004-05-01

    We discuss the magnetic phase diagram for the Hubbard model with magnetic frustration obtained within the dynamical mean-field theory. Most interesting is the appearance of a first-order paramagnetic metal to antiferromagnetic insulator transition for the magnetically frustrated lattice at half filling. For finite doping the antiferromagnetic phase is susceptible to phase separation and competes with an itinerant ferromagnetic phase (Nagaoka ferromagnetism), leading to an unexpectedly rich magnetic phase diagram.

  3. Four-dimensional lattice results on the MSSM electroweak phase transition

    CERN Document Server

    Csikor, Ferenc; Hegedüs, P; Jakovác, A; Katz, S D; Piróth, A

    2001-01-01

    We present the results of our large scale 4-dimensional (4d) lattice simulations for the MSSM electroweak phase transition (EWPT). We carried out infinite volume and continuum limit extrapolations and found a transition whose strength agrees well with perturbation theory. We determined the properties of the bubble wall that are important for a successful baryogenesis.

  4. Electroweak Baryogenesis and Higgs Properties

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Timothy; /SLAC; Morrissey, David E.; /TRIUMF; Pierce, Aaron; /Michigan U., MCTP

    2012-03-13

    We explore the connection between the strength of the electroweak phase transition and the properties of the Higgs boson. Our interest is in regions of parameter space that can realize electroweak baryogenesis. We do so in a simplified framework in which a single Higgs field couples to new scalar fields charged under SU(3){sub c} by way of the Higgs portal. Such new scalars can make the electroweak phase transition more strongly first-order, while contributing to the effective Higgs boson couplings to gluons and photons through loop effects. For Higgs boson masses in the range 115 {approx}< m{sub h} {approx}< 130 GeV, whenever the phase transition becomes strong enough for successful electroweak baryogenesis, we find that Higgs boson properties are modified by an amount observable by the LHC. We also discuss the baryogenesis window of the minimal supersymmetric standard model (MSSM), which appears to be under tension. Furthermore, we argue that the discovery of a Higgs boson with standard model-like couplings to gluons and photons will rule out electroweak baryogenesis in the MSSM.

  5. Split NMSSM with electroweak baryogenesis

    CERN Document Server

    Demidov, S V; Kirpichnikov, D V

    2016-01-01

    In light of the Higgs boson discovery we reconsider generation of the baryon asymmetry in the non-minimal split Supersymmetry model with an additional singlet superfield in the Higgs sector. We find that successful baryogenesis during the first order electroweak phase transition is possible within phenomenologically viable part of the model parameter space. We discuss several phenomenological consequences of this scenario, namely, predictions for the electric dipole moments of electron and neutron and collider signatures of light charginos and neutralinos.

  6. Split NMSSM with electroweak baryogenesis

    OpenAIRE

    Demidov, S.; Gorbunov, D; Kirpichnikov, D.

    2016-01-01

    In light of the Higgs boson discovery and other results of the LHC we re-consider generation of the baryon asymmetry in the split Supersymmetry model with an additional singlet superfield in the Higgs sector (non-minimal split SUSY). We find that successful baryogenesis during the first order electroweak phase transition is possible within a phenomenologically viable part of the model parameter space. We discuss several phenomenological consequences of this scenario, namely, predictions for t...

  7. Kinetic arrest of field-temperature induced first order phase transition in quasi-one dimensional spin system Ca3Co2O6

    Science.gov (United States)

    De, Santanu; Kumar, Kranti; Banerjee, A.; Chaddah, P.

    2016-05-01

    We have found that the geometrically frustrated spin chain compound Ca3Co2O6 belonging to Ising like universality class with uniaxial anisotropy shows kinetic arrest of first order intermediate phase (IP) to ferrimagnetic (FIM) transition. In this system, dc magnetization measurements followed by different protocols suggest the coexistence of high temperature IP with equilibrium FIM phase in low temperature. Formation of metastable state due to hindered first order transition has also been probed through cooling and heating in unequal field (CHUF) protocol. Kinetically arrested high temperature IP appears to persist down to almost the spin freezing temperature in this system.

  8. Weak arrest-like and field-driven first order magnetic phase transitions of itinerant Fe3Ga4 revealed by magnetization and magnetoresistance isotherms

    Science.gov (United States)

    Samatham, S. Shanmukharao; Suresh, K. G.

    2017-01-01

    The detailed magnetic study of complex 3d-electron based Fe3Ga4 is reported. It undergoes paramagnetic to antiferromagnetic (TN) and antiferromagnetic to ferromagnetic (TC) transitions respectively around 380 and 70 K. The thermal hysteresis of field-cooled cooling (FCC) and field-cooled warming (FCW) hints at first order phase transition below Curie temperature. A weak phase coexistence of ferro and antiferromagnetic phases is suggested by exploring the arrest-like first-order phenomenon. In the intermediate temperature range, field-driven metamagnetic transition from antiferro to ferromagnetic phase is confirmed. Further bringing the system very near to TN, field-induced transitions disappear and above TN predominant paramagnetic contribution is evident. The magnetic H-T phase diagram distinguishing different magnetic phases of Fe3Ga4 is obtained.

  9. Critical nonequilibrium relaxation in the Swendsen-Wang algorithm in the Berezinsky-Kosterlitz-Thouless and weak first-order phase transitions

    Science.gov (United States)

    Nonomura, Yoshihiko; Tomita, Yusuke

    2015-12-01

    Recently we showed that the critical nonequilibrium relaxation in the Swendsen-Wang algorithm is widely described by the stretched-exponential relaxation of physical quantities in the Ising or Heisenberg models. Here we make a similar analysis in the Berezinsky-Kosterlitz-Thouless phase transition in the two-dimensional (2D) X Y model and in the first-order phase transition in the 2D q =5 Potts model and find that these phase transitions are described by the simple exponential relaxation and power-law relaxation of physical quantities, respectively. We compare the relaxation behaviors of these phase transitions with those of the second-order phase transition in the three- and four-dimensional X Y models and in the 2D q -state Potts models for 2 ≤q ≤4 and show that the species of phase transitions can be clearly characterized by the present analysis. We also compare the size dependence of relaxation behaviors of the first-order phase transition in the 2D q =5 and 6 Potts models and propose a quantitative criterion on "weakness" of the first-order phase transition.

  10. "Big Bang'' as a result of first-order phase transition driven by changing scalar curvature in expanding early Universe: "hyperinflation'' scenario

    CERN Document Server

    Pashitskii, E A

    2015-01-01

    We suggest that the "Big Bang" may be a result of the first-order phase transition driven by changing scalar curvature of the 4D space-time in expanding cold Universe, filled with nonlinear scalar field $\\phi $ and neutral matter with equation of state $p=\

  11. Lower bound on the electroweak wall velocity from hydrodynamic instability

    Energy Technology Data Exchange (ETDEWEB)

    Mégevand, Ariel; Membiela, Federico Agustín; Sánchez, Alejandro D. [IFIMAR (CONICET-UNMdP), Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Deán Funes (7600) 3350 Mar del Plata (Argentina)

    2015-03-27

    The subsonic expansion of bubbles in a strongly first-order electroweak phase transition is a convenient scenario for electroweak baryogenesis. For most extensions of the Standard Model, stationary subsonic solutions (i.e., deflagrations) exist for the propagation of phase transition fronts. However, deflagrations are known to be hydrodynamically unstable for wall velocities below a certain critical value. We calculate this critical velocity for several extensions of the Standard Model and compare with an estimation of the wall velocity. In general, we find a region in parameter space which gives stable deflagrations as well as favorable conditions for electroweak baryogenesis.

  12. Electroweak baryogenesis and gravitational waves from a real scalar singlet

    CERN Document Server

    Vaskonen, Ville

    2016-01-01

    We consider a real scalar singlet field which provides a strong first order electroweak phase transition via its coupling to the Higgs boson, and gives a CP violating contribution on the top quark mass via a dimension 6 operator. We study the correlation between the baryon-to-entropy ratio produced by electroweak baryogenesis, and the gravitational wave signal from the electroweak phase transition. We show that the future gravitational wave experiments can test in particular the region of the model parameter space where the observed baryon-to-entropy ratio can be obtained even if the new physics scale, which is explicit in the dimension 6 operator, is high.

  13. Phase-shifting algorithms for a finite number of harmonics: first-order analysis by solving linear systems.

    Science.gov (United States)

    Téllez-Quiñones, Alejandro; Malacara-Doblado, Daniel; García-Márquez, Jorge

    2012-04-01

    From generalized phase-shifting equations, we propose a simple linear system analysis for algorithms with equally and nonequally spaced phase shifts. The presence of a finite number of harmonic components in the fringes of the intensity patterns is taken into account to obtain algorithms insensitive to these harmonics. The insensitivity to detuning for the fundamental frequency is also considered as part of the description of this study. Linear systems are employed to recover the desired insensitivity properties that can compensate linear phase shift errors. The analysis of the wrapped phase equation is carried out in the Fourier frequency domain.

  14. Phenomenology and Cosmology of an Electroweak Pseudo-Dilaton and Electroweak Baryons

    CERN Document Server

    Campbell, Bruce A; Olive, Keith A

    2012-01-01

    In many strongly-interacting models of electroweak symmetry breaking the lowest-lying observable particle is a pseudo-Goldstone boson of approximate scale symmetry, the pseudo-dilaton. Its interactions with Standard Model particles can be described using a low-energy effective nonlinear chiral Lagrangian supplemented by terms that restore approximate scale symmetry, yielding couplings of the pseudo-dilaton that differ from those of a Standard Model Higgs boson by fixed factors. We review the experimental constraints on such a pseudo-dilaton in light of new data from the LHC and elsewhere. The effective nonlinear chiral Lagrangian has Skyrmion solutions that may be identified with the `electroweak baryons' of the underlying strongly-interacting theory, whose nature may be revealed by the properties of the Skyrmions. We discuss the finite-temperature electroweak phase transition in the low-energy effective theory, finding that the possibility of a first-order electroweak phase transition is resurrected. We disc...

  15. First order quantum phase transitions of the XX spin-1/2 chain in a uniform transverse field

    Energy Technology Data Exchange (ETDEWEB)

    Pan Feng [Department of Physics, Liaoning Normal University, Dalian 116029 (China) and Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States)]. E-mail: daipan@dlut.edu.cn; Ma Nan [Department of Physics, Liaoning Normal University, Dalian 116029 (China); Guan Xin [Department of Physics, Liaoning Normal University, Dalian 116029 (China); Draayer, J.P. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States)

    2007-08-06

    Quantum phase transitional behavior of a finite periodic XX spin-12 chain with nearest neighbor interaction in a uniform transverse field is studied based on the simple exact solutions. It is found that there are [N/2] level-crossing points in the ground state, where N is the periodic number of the system and [x] stands for the integer part of x, when the interaction strength and magnitude of the magnetic field satisfy certain conditions. The quantum phase transitional behavior in the thermodynamic is also studied.

  16. Electroweak Baryogenesis and Higgs Signatures

    CERN Document Server

    Cohen, Timothy; Pierce, Aaron

    2012-01-01

    We explore the connection between the strength of the electroweak phase transition and the properties of the Higgs boson. Our interest is in regions of parameter space that can realize electroweak baryogenesis. We do so in a simplified framework in which a single Higgs field couples to new scalar fields charged under SU(3)_c by way of the Higgs portal. Such new scalars can make the electroweak phase transition more strongly first-order, while contributing to the effective Higgs boson couplings to gluons and photons through loop effects. For Higgs boson masses in the range 115 GeV < m_h < 130 GeV, whenever the phase transition becomes strong enough for successful electroweak baryogenesis, we find that Higgs boson properties are modified by an amount observable by the LHC. We also discuss the baryogenesis window of the minimal supersymmetric standard model (MSSM), which appears to be under tension. Furthermore, we argue that the discovery of a Higgs boson with standard model-like couplings to gluons and p...

  17. 3-D lattice simulation of the electroweak phase transition at small Higgs mass

    CERN Document Server

    Ilgenfritz, E M; Perlt, H; Schiller, A

    1995-01-01

    We study the electroweak phase transition by lattice simulations of an effective 3-dimensional theory, for a Higgs mass of about 35 GeV. In the broken symmetry phase our results on masses and the Higgs condensate are consistent with 2-loop perturbative results. However we find a non-perturbative lowering of the transition temperature, similar to the one previously found at m_H = 80 GeV. For the symmetric phase, bound state masses and the static force are determined and compared with results for pure SU(2) theory.

  18. Fourier transform infrared spectroscopic study of the kinetics of a first-order phase transition in tridecanoic acid CH3(CH2)11COOH

    Science.gov (United States)

    Marikhin, V. A.; Myasnikova, L. P.; Radovanova, E. I.; Volchek, B. Z.; Medvedeva, D. A.

    2017-02-01

    The structural changes in crystalline lamella cores of tridecanoic acid CH3(CH2)11COOH during heating in the range from the temperature T 1 = 13.5°C to T 2 > T m = 41.6°C have been investigated using Fourier transform infrared spectroscopy. The behavior of the bands of rocking (in the region of 720 cm-1) and bending (in the region of 1470 cm-1) vibrations of CH2 groups in tridecanoic acid methylene segments has been analyzed. It has been shown that, in the first-order phase transition region ( T s-s 36°C) within a narrow temperature range (Δ T 1 ≤ 1 K), there is a gradual transformation of the initial triclinic subcell into the hexagonal subcell. The mechanism of this transition has been considered in terms of the theory of diffuse first-order phase transitions.

  19. Magnetic-field-induced first-order phase transitions in Ca3(Ru1-xFex)2 O7 with unusual irreversible behaviors

    Science.gov (United States)

    Zhu, Mengze; Peng, Jin; Zou, Tao; Hong, Tao; Prokes, Karel; Mahanti, S. D.; Mao, Zhiqiang; Ke, Xianglin

    Neutron diffraction measurements reveal a magnetic-field-induced incommensurate-commensurate magnetic structure transition in a bilayer ruthenate Ca3(Ru1-xFex)2 O7 (x = 0.05). The transition is of first-order in nature, and exhibits intriguing irreversible behaviors at low temperature, i.e. the zero-field incommensurate state before and after field sweeping showing very distinct magnetic ordering wave vectors. The difference in the wavelength of magnetic ordering is strongly temperature-dependent, and disappears gradually as temperature raises. This unusual irreversibility in magnetic ordering vector is rarely observed, and in disagreement with phase coexistence phenomena that is commonly seen in other irreversible first-order phase transitions. Nevertheless, our results demonstrate that thermal fluctuations also play an essential role in this unusual behavior.

  20. Assessment of Ex-Vitro Anaerobic Digestion Kinetics of Crop Residues Through First Order Exponential Models: Effect of LAG Phase Period and Curve Factor

    Directory of Open Access Journals (Sweden)

    Abdul Razaque Sahito

    2013-04-01

    Full Text Available Kinetic studies of AD (Anaerobic Digestion process are useful to predict the performance of digesters and design appropriate digesters and also helpful in understanding inhibitory mechanisms of biodegradation. The aim of this study was to assess the anaerobic kinetics of crop residues digestion with buffalo dung. Seven crop residues namely, bagasse, banana plant waste, canola straw, cotton stalks, rice straw, sugarcane trash and wheat straw were selected from the field and were analyzed on MC (Moisture Contents, TS (Total Solids and VS (Volatile Solids with standard methods. In present study, three first order exponential models namely exponential model, exponential lag phase model and exponential curve factor model were used to assess the kinetics of the AD process of crop residues and the effect of lag phase and curve factor was analyzed based on statistical hypothesis testing and on information theory. Assessment of kinetics of the AD of crop residues and buffalo dung follows the first order kinetics. Out of the three models, the simple exponential model was the poorest model, while the first order exponential curve factor model is the best fit model. In addition to statistical hypothesis testing, the exponential curve factor model has least value of AIC (Akaike's Information Criterion and can generate methane production data more accurately. Furthermore, there is an inverse linear relationship between the lag phase period and the curve factor.

  1. Specific heat and entropy change at the first order phase transition of La(Fe-Mn-Si)13-H compounds

    Science.gov (United States)

    Basso, Vittorio; Küpferling, Michaela; Curcio, Carmen; Bennati, Cecilia; Barzca, Alexander; Katter, Matthias; Bratko, Milan; Lovell, Edmund; Turcaud, Jeremy; Cohen, Lesley F.

    2015-08-01

    In this paper, we present the results of an experimental investigation on the magnetocaloric properties of hydrogenated La(Fe-Mn-Si)13-H with Mn substituting Fe to finely tune the transition temperature. We measured the specific heat under magnetic field cp(H, T) and the magnetic field induced isothermal entropy change Δs(H, T) of a series of compounds by direct Peltier calorimetry. Results show that increasing Mn from 0.06 to 0.46 reduces the transition temperature from 339 K to 270 K whilst the total entropy change due to a 1.5 T field is depressed from 18.7 J kg-1 K-1 to 10.2 J kg-1 K-1 and the thermal hysteresis similarly is reduced from 1.5 K to zero. In the paper, we interpret the results in terms of a magnetic phase transition changing from the first to the second order with increasing Mn content, and we discuss the value of the results for magnetic cooling applications.

  2. Real-Time History of the Cosmological Electroweak Phase Transition

    CERN Document Server

    Kurki-Suonio, H

    1996-01-01

    We study numerically the real-time history of the cosmological electrow= eak phase transition, as it may take place in the Standard Model or in MSSM f= or m_H < m_W according to recent lattice results. We follow the nucleated bubble= s from the initial stages of acceleration and rapid growth, through collisions w= ith compression waves resulting in slowing down and reheating to T_c, until t= he final stages of slow growth and evaporation. We find that collisions with compression waves may make the bubble walls oscillate in the radial direc= tion, and that reheating to T_c takes generically place.

  3. First-order commensurate-incommensurate magnetic phase transition in the coupled FM spin-1/2 two-leg ladders

    CERN Document Server

    Jahangiri, J; Mahdavifar, S; Shayesteh, S Farjami

    2015-01-01

    We consider the spin-1/2 two-leg ladders with ferromagnetic (FM) interactions along legs and rungs. Using the stochastic series expansion QMC method, we study the low-temperature magnetic behavior of the system. An isolated spin-1/2 FM two-leg ladder is in the gapped saturated FM phase at zero temperature. As soon as the spin-1/2 FM two-leg ladders are connected with antiferromagnetic (AFM) inter-ladder interaction, a first-order commensurate-incommensurate quantum phase transition occurs in the ground state magnetic phase diagram. In fact a jump in the magnetization curve is observed. We found that, coupled spin-1/2 FM two-leg ladders are in a nonmagnetic phase at zero temperature. Applying a magnetic field, the ground state of coupled spin-1/2 FM two-leg ladders remains in the nonmagnetic phase up to a quantum saturate critical field.

  4. Ashkin-Teller criticality and weak first-order behavior of the phase transition to a fourfold degenerate state in two-dimensional frustrated Ising antiferromagnets

    Science.gov (United States)

    Liu, R. M.; Zhuo, W. Z.; Chen, J.; Qin, M. H.; Zeng, M.; Lu, X. B.; Gao, X. S.; Liu, J.-M.

    2017-07-01

    We study the thermal phase transition of the fourfold degenerate phases (the plaquette and single-stripe states) in the two-dimensional frustrated Ising model on the Shastry-Sutherland lattice using Monte Carlo simulations. The critical Ashkin-Teller-like behavior is identified both in the plaquette phase region and the single-stripe phase region. The four-state Potts critical end points differentiating the continuous transitions from the first-order ones are estimated based on finite-size-scaling analyses. Furthermore, a similar behavior of the transition to the fourfold single-stripe phase is also observed in the anisotropic triangular Ising model. Thus, this work clearly demonstrates that the transitions to the fourfold degenerate states of two-dimensional Ising antiferromagnets exhibit similar transition behavior.

  5. Potential energy landscape of the apparent first-order phase transition between low-density and high-density amorphous ice.

    Science.gov (United States)

    Giovambattista, Nicolas; Sciortino, Francesco; Starr, Francis W; Poole, Peter H

    2016-12-14

    The potential energy landscape (PEL) formalism is a valuable approach within statistical mechanics to describe supercooled liquids and glasses. Here we use the PEL formalism and computer simulations to study the pressure-induced transformations between low-density amorphous ice (LDA) and high-density amorphous ice (HDA) at different temperatures. We employ the ST2 water model for which the LDA-HDA transformations are remarkably sharp, similar to what is observed in experiments, and reminiscent of a first-order phase transition. Our results are consistent with the view that LDA and HDA configurations are associated with two distinct regions (megabasins) of the PEL that are separated by a potential energy barrier. At higher temperature, we find that low-density liquid (LDL) configurations are located in the same megabasin as LDA, and that high-density liquid (HDL) configurations are located in the same megabasin as HDA. We show that the pressure-induced LDL-HDL and LDA-HDA transformations occur along paths that interconnect these two megabasins, but that the path followed by the liquid is different from the path followed by the amorphous solid. At higher pressure, we also study the liquid-to-ice-VII first-order phase transition, and find that the behavior of the PEL properties across this transition is qualitatively similar to the changes found during the LDA-HDA transformation. This similarity supports the interpretation that the LDA-HDA transformation is a first-order phase transition between out-of-equilibrium states. Finally, we compare the PEL properties explored during the LDA-HDA transformations in ST2 water with those reported previously for SPC/E water, for which the LDA-HDA transformations are rather smooth. This comparison illuminates the previous work showing that, at accessible computer times scales, a liquid-liquid phase transition occurs in the case of ST2 water, but not for SPC/E water.

  6. Potential energy landscape of the apparent first-order phase transition between low-density and high-density amorphous ice

    Science.gov (United States)

    Giovambattista, Nicolas; Sciortino, Francesco; Starr, Francis W.; Poole, Peter H.

    2016-12-01

    The potential energy landscape (PEL) formalism is a valuable approach within statistical mechanics to describe supercooled liquids and glasses. Here we use the PEL formalism and computer simulations to study the pressure-induced transformations between low-density amorphous ice (LDA) and high-density amorphous ice (HDA) at different temperatures. We employ the ST2 water model for which the LDA-HDA transformations are remarkably sharp, similar to what is observed in experiments, and reminiscent of a first-order phase transition. Our results are consistent with the view that LDA and HDA configurations are associated with two distinct regions (megabasins) of the PEL that are separated by a potential energy barrier. At higher temperature, we find that low-density liquid (LDL) configurations are located in the same megabasin as LDA, and that high-density liquid (HDL) configurations are located in the same megabasin as HDA. We show that the pressure-induced LDL-HDL and LDA-HDA transformations occur along paths that interconnect these two megabasins, but that the path followed by the liquid is different from the path followed by the amorphous solid. At higher pressure, we also study the liquid-to-ice-VII first-order phase transition, and find that the behavior of the PEL properties across this transition is qualitatively similar to the changes found during the LDA-HDA transformation. This similarity supports the interpretation that the LDA-HDA transformation is a first-order phase transition between out-of-equilibrium states. Finally, we compare the PEL properties explored during the LDA-HDA transformations in ST2 water with those reported previously for SPC/E water, for which the LDA-HDA transformations are rather smooth. This comparison illuminates the previous work showing that, at accessible computer times scales, a liquid-liquid phase transition occurs in the case of ST2 water, but not for SPC/E water.

  7. First-order superfluid to valence-bond solid phase transitions in easy-plane SU (N ) magnets for small N

    Science.gov (United States)

    D'Emidio, Jonathan; Kaul, Ribhu K.

    2016-02-01

    We consider the easy-plane limit of bipartite SU (N ) Heisenberg Hamiltonians, which have a fundamental representation on one sublattice and the conjugate to fundamental on the other sublattice. For N =2 the easy plane limit of the SU(2) Heisenberg model is the well-known quantum X Y model of a lattice superfluid. We introduce a logical method to generalize the quantum X Y model to arbitrary N , which keeps the Hamiltonian sign-free. We show that these quantum Hamiltonians have a world-line representation as the statistical mechanics of certain tightly packed loop models of N colors in which neighboring loops are disallowed from having the same color. In this loop representation we design an efficient Monte Carlo cluster algorithm for our model. We present extensive numerical results for these models on the two dimensional square lattice, where we find the nearest neighbor model has superfluid order for N ≤5 and valence-bond order for N >5 . By introducing SU (N ) easy-plane symmetric four-spin couplings we are able to tune across the superfluid-VBS phase boundary for all N ≤5 . We present clear evidence that this quantum phase transition is first order for N =2 and N =5 , suggesting that easy-plane deconfined criticality runs away generically to a first-order transition for small N .

  8. A first-order magnetic phase transition near 15 K with novel magnetic-field-induced effects in Er5Si3.

    Science.gov (United States)

    Mohapatra, Niharika; Mukherjee, K; Iyer, Kartik K; Sampathkumaran, E V

    2011-12-14

    We present magnetic characterization of a binary rare-earth intermetallic compound Er(5)Si(3), crystallizing in Mn(5)Si(3)-type hexagonal structure, through magnetization, heat capacity, electrical resistivity and magnetoresistance measurements. Our investigations confirm that the compound exhibits two magnetic transitions with decreasing temperature, the first one at 35 K and the second one at 15 K. The present results reveal that the second magnetic transition is a disorder-broadened first-order transition, as shown by thermal hysteresis in the measured data. Another important finding is that, below 15 K, there is a magnetic-field-induced transition with a hysteretic effect with the electrical resistance getting unusually enhanced at this transition and the magnetoresistance is found to exhibit intriguing magnetic-field dependence, indicating novel magnetic phase coexistence phenomenon. It thus appears that this compound is characterized by interesting magnetic anomalies in the temperature-magnetic-field phase diagram.

  9. Split NMSSM with electroweak baryogenesis

    Science.gov (United States)

    Demidov, S. V.; Gorbunov, D. S.; Kirpichnikov, D. V.

    2016-11-01

    In light of the Higgs boson discovery and other results of the LHC we re-consider generation of the baryon asymmetry in the split Supersymmetry model with an additional singlet superfield in the Higgs sector (non-minimal split SUSY). We find that successful baryogenesis during the first order electroweak phase transition is possible within a phenomenologically viable part of the model parameter space. We discuss several phenomenological consequences of this scenario, namely, predictions for the electric dipole moments of electron and neutron and collider signatures of light charginos and neutralinos.

  10. Magnetic and magnetocaloric properties of the first-order phase transition in Sm0.5+ x Sr0.5- x MnO3 compounds

    Science.gov (United States)

    Thanh, Tran Dang; Linh, Dinh Chi; Manh, Tien Van; Nan, Wen-Zhe; Yu, Seong-Cho; Piao, Hong-Guang; Pan, Liqing

    2016-08-01

    In this work, we present a detailed study on the magnetic and the magnetocaloric properties of Sm0.5+ x Sr0.5- x MnO3 compounds with x = 0 - 0.1, which were prepared by using a solid-state reaction method. The x-dependent magnetic, as well as magnetocaloric, properties, including the magnetic phase transition, have been studied. The increase in Sm/Sr ratio plays an important role in controlling the Curie temperature ( T C ). We point out that all the samples undergo a first-order phase transition and exhibit a giant magnetocaloric effect. The magnetic entropy change (Δ S m ) of samples was calculated based on isothermal M( H, T) data. The maximum value of Δ S m (denoted as |Δ S max|) at around T C is found to be 2.6 - 8.9 J·kg -1·K -1 for Δ H = 30 kOe and depends on the value of x. We have also used the universal master curve method for the temperature dependences of Δ S m curves measured at different Δ H values, Δ S m ( T,Δ H), to distinguish the magnetic order in the samples. Interestingly, none of the Δ S m ( T,Δ H) curves for the samples follow the universal master curve, Δ S m ( T,Δ H)/Δ S max versus θ = ( T -T C )/( T r - T C ). As a consequence, a breakdown in the universal behavior of Δ S m ( T,Δ H)/Δ S max versus θ curve is another feature confirming a first-order phase-transition nature.

  11. Az elektrogyenge fázisátmenet (The electroweak phase transition)

    CERN Document Server

    Piróth, A

    2000-01-01

    The electroweak phase transition provides the most attractive framework to account for the baryon asymmetry of the universe. Comparing results of perturbative and nonperturbative studies is not straightforward, however, due to the different coupling constant definitions. The perturbative one stems from the $\\bar{\\mathrm{MS}}$ subtraction scheme, while the nonperturbative one uses the static quark potential. The momentum-space perturbative static potential is calculated in the SU(2)--Higgs model, and is Fourier transformed into coordinate space. Based on the connection between the coupling constants, two-loop perturbative and 4-dimensional lattice simulation results are contrasted. The thermodynamical parameters of the phase transition indicate that perturbative results are reliable only for low Higgs masses, far from the endpoint. The value of the endpoint can be refined to $72.1\\pm1.4$ GeV. The Higgs mass range for which dimensional reduction yields reliable results is identified. As an extension of the stan...

  12. First-order magnetic phase transition in PrCo{sub 9}Si{sub 4} and NdCo{sub 9}Si{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    El-Hagary, M. E-mail: magdy@ifp.tuwien.ac.at; Michor, H. E-mail: michor@ifp.tuwien.ac.at; Bauer, E.; Della Mea, M.; Hense, K.; Hilscher, G

    2004-05-01

    The tetragonal compounds PrCo{sub 9}Si{sub 4} and NdCo{sub 9}Si{sub 4} have been studied by specific heat, electrical resistivity and magnetic susceptibility measurements. The onset of ferromagnetic order is observed at Curie temperatures T{sub C}{approx_equal}24 and 12 K for PrCo{sub 9}Si{sub 4} and NdCo{sub 9}Si{sub 4}, respectively. Thermodynamic and transport data of both compounds reveal a first-order phase transition from the paramagnetic to the ferromagnetic state which can be deduced from step like anomalies in the resistivity data as well as sharp peak-type anomalies of the specific heat.

  13. Stochastic resonance and dynamic first-order pseudo-phase-transitions in the irreversible growth of thin films under spatially periodic magnetic fields.

    Science.gov (United States)

    Loscar, Ernesto S; Candia, Julián

    2013-10-01

    We study the irreversible growth of magnetic thin films under the influence of spatially periodic fields by means of extensive Monte Carlo simulations. We find first-order pseudo-phase-transitions that separate a dynamically disordered phase from a dynamically ordered phase. By analogy with time-dependent oscillating fields applied to Ising-type models, we qualitatively associate this dynamic transition with the localization-delocalization transition of spatial hysteresis loops. Depending on the relative width of the magnetic film L compared to the wavelength of the external field λ, different transition regimes are observed. For small systems (L λ), the transition is driven by anomalous stochastic resonance. The origin of the latter is identified as due to the emergence of an additional relevant length scale, namely, the roughness of the spin domain switching interface. The distinction between different stochastic resonance regimes is discussed at length both qualitatively by means of snapshot configurations and quantitatively via residence-length and order-parameter probability distributions.

  14. Electroweak Baryogenesis with Anomalous Higgs Couplings

    CERN Document Server

    Kobakhidze, Archil; Yue, Jason

    2015-01-01

    We investigate feasibility of efficient baryogenesis at the electroweak scale within the effective field theory framework based on a non-linear realisation of the electroweak gauge symmetry. In this framework the LHC Higgs boson is described by a singlet scalar field, which, therefore, admits new interactions. Assuming that Higgs couplings with the eletroweak gauge bosons are as in the Standard Model, we demonstrate that the Higgs cubic coupling and the CP-violating Higgs-top quark anomalous couplings alone may drive the a strongly first-order phase transition. The distinguished feature of this transition is that the anomalous Higgs vacuum expectation value is generally non-zero in both phases. We identify a range of anomalous couplings, consistent with current experimental data, where sphaleron rates are sufficiently fast in the 'symmetric' phase and are suppressed in the 'broken' phase and demonstrate that the desired baryon asymmetry can indeed be generated in this framework. This range of the Higgs anomal...

  15. Temperature-dependent first-order reversal curve measurements on unusually hard magnetic low-temperature phase of MnBi

    Science.gov (United States)

    Muralidhar, Shreyas; Gräfe, Joachim; Chen, Yu-Chun; Etter, Martin; Gregori, Giuliano; Ener, Semih; Sawatzki, Simon; Hono, Kazuhiro; Gutfleisch, Oliver; Kronmüller, Helmut; Schütz, Gisela; Goering, Eberhard J.

    2017-01-01

    We have performed first-order reversal curve (FORC) measurements to investigate the irreversible magnetization processes in the low-temperature phase of MnBi. Using temperature-dependent FORC analysis, we are able to provide a clear insight into the effects of microstructural parameters such as grain diameter, shape, and surface composition on the coercivity of nucleation hardened permanent magnet MnBi. FORC diagrams of MnBi show a unique broadening and narrowing of the coercive field distribution with increasing temperature. We were able to microscopically identify the reason for this behavior, based on the shift in the single domain critical diameter from nearly 1 to 2 μ m , thereby changing the dependence of coercivity with particle size. This is based on a strong increase in the uniaxial anisotropy constant with increasing temperature. Furthermore, the results also give an additional confirmation that the magnetic hardening in low-temperature phase MnBi occurs due to nucleation mechanisms. In our case, we show that temperature-dependent FORC measurements provide a powerful tool for the microscopic understanding of high-performance permanent magnet systems.

  16. DNA-gelatin complex coacervation, UCST and first-order phase transition of coacervate to anisotropic ion gel in 1-methyl-3-octylimidazolium chloride ionic liquid solutions.

    Science.gov (United States)

    Rawat, Kamla; Aswal, V K; Bohidar, H B

    2012-12-27

    Study of kinetics of complex coacervation occurring in aqueous 1-octyl-3-methylimidazolium chloride ionic liquid solution of low charge density polypeptide (gelatin A) and 200 base pair DNA, and thermally activated coacervate into anisotropic gel transition, is reported here. Associative interaction between DNA and gelatin A (GA) having charge ratio (DNA:GA = 16:1) and persistence length ratio (5:1) was studied at fixed DNA (0.005% (w/v)) and varying GA concentration (C(GA) = 0-0.25% (w/v)). The interaction profile was found to be strongly hierarchical and revealed three distinct binding regions: (i) Region I showed DNA-condensation (primary binding) for C(GA) coacervation. (iii) Region III (0.15 coacervate was found to be protein concentration specific in Raman studies. The binding profile of DNA-GA complex with IL concentration revealed optimum IL concentration (=0.05% (w/v)) was required to maximize the interactions. Small angle neutron scattering (SANS) data of coacervates gave static structure factor profiles, I(q) versus wave vector q, that were remarkably similar and invariant of protein concentration. This data could be split into two distinct regions: (i) for 0.0173 coacervate phase resided close to the gelation state of the protein. Thus, on a heating-cooling cycle (heating to 50 °C followed by cooling to 20 °C), the heterogeneous coacervate exhibited an irreversible first-order phase transition to an anisotropic ion gel. This established a coacervate-ion gel phase diagram having a well-defined UCST.

  17. Positive magnetoresistance and large magnetostriction at first-order antiferro-ferromagnetic phase transitions in RMn{sub 2}Si{sub 2} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gerasimov, E G; Mushnikov, N V [Institute of Metals Physics, Ural Division of the Russian Academy of Science, Sofia Kovalevskaya Street, 18, 620041 Ekaterinburg (Russian Federation); Koyama, K; Watanabe, K [High Field Laboratory for Superconducting Materials HFLSM, Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Kanomata, T [Department of Applied Physics, Faculty of Engineering, Tohoku Gakuin University, Tagajo, Miyagi 985 (Japan)], E-mail: gerasimov@imp.uran.ru

    2008-11-05

    The magnetostriction and magnetoresistance associated with the field-induced and spontaneous first-order antiferro-ferromagnetic (AF-F) phase transitions have been studied for quasi-single-crystalline samples of La{sub 0.25}Sm{sub 0.75}Mn{sub 2}Si{sub 2}, La{sub 0.25}Y{sub 0.75}Mn{sub 2}Si{sub 2} and La{sub 0.27}Y{sub 0.73}Mn{sub 2}Si{sub 2} compounds with natural layered ThCr{sub 2}Si{sub 2}-type structure. It was found that both the spontaneous and field-induced AF-F transitions are accompanied by a large volume magnetostriction {delta}V/V{approx}2 x 10{sup -3} and anisotropic linear changes of the lattice parameters {delta}a/a{approx}1.6 x 10{sup -3}, {delta}c/c{approx}-0.75 x 10{sup -3}. The field-induced AF-F magnetic phase transition has been observed in magnetic fields applied both along the c-axis and in the basal plane, and the magnetostriction value is virtually independent of the direction of applied field. It has been found also that the magnetoresistance is positive in these compounds (the value of the electrical resistance in the ferromagnetic state is higher than that in the antiferromagnetic state) for the fields applied both along the c-axis and in the basal plane. The value of the magnetoresistance observed along the c-axis is 30 times as high as that in the basal plane. The obtained results indicate that the electronic band structure changes are likely responsible for the AF-F magnetic phase transitions observed in the RMn{sub 2}X{sub 2} compounds.

  18. Lepton-Flavored Electroweak Baryogenesis

    CERN Document Server

    Guo, Huai-Ke; Liu, Tao; Ramsey-Musolf, Michael; Shu, Jing

    2016-01-01

    We explore lepton-flavored electroweak baryogenesis, driven by CP-violation in leptonic Yukawa sector, using the $\\tau-\\mu$ system in the two Higgs doublet model as an example. This setup generically yields, together with the flavor-changing decay $h\\to \\tau \\mu$, a tree-level Jarlskog-invariant that can drive dynamical generation of baryon asymmetry during a first-order electroweak phase transition and results in CP-violating effect in the decay $h\\to \\tau\\tau$. We find that the observed baryon asymmetry can be generated in parameter space compatible with current experimental results for the decays $h\\to \\tau \\mu$, $h\\to \\tau\\tau$ and $\\tau \\rightarrow \\mu \\gamma$, as well as the present bound on the electric dipole moment of the electron. The baryon asymmetry generated is intrinsically correlated with the CP-violating decay $h\\to \\tau\\tau$ and the flavor-changing decay $h\\to \\tau\\mu$, which thus may serve as "smoking guns" to test lepton-flavored electroweak baryogenesis.

  19. Critical phenomena at a first-order phase transition in a lattice of glow lamps: Experimental findings and analogy to neural activity

    Science.gov (United States)

    Minati, Ludovico; de Candia, Antonio; Scarpetta, Silvia

    2016-07-01

    Networks of non-linear electronic oscillators have shown potential as physical models of neural dynamics. However, two properties of brain activity, namely, criticality and metastability, remain under-investigated with this approach. Here, we present a simple circuit that exhibits both phenomena. The apparatus consists of a two-dimensional square lattice of capacitively coupled glow (neon) lamps. The dynamics of lamp breakdown (flash) events are controlled by a DC voltage globally connected to all nodes via fixed resistors. Depending on this parameter, two phases having distinct event rate and degree of spatiotemporal order are observed. The transition between them is hysteretic, thus a first-order one, and it is possible to enter a metastability region, wherein, approaching a spinodal point, critical phenomena emerge. Avalanches of events occur according to power-law distributions having exponents ≈3/2 for size and ≈2 for duration, and fractal structure is evident as power-law scaling of the Fano factor. These critical exponents overlap observations in biological neural networks; hence, this circuit may have value as building block to realize corresponding physical models.

  20. Effect of a weak external electric field on the kinetics of the ordering of ferroelectrics upon first-order phase transitions

    Science.gov (United States)

    Mazur, O. Yu.; Stefanovich, L. I.; Yurchenko, V. M.

    2016-08-01

    The kinetics of the formation and growth of 180° domains in a weak quasi-stationary external electric field has been considered in the framework of the phenomenological Ginzburg-Landau model using the example of sodium nitrite (NaNO2) crystals that undergo a first-order ferroelectric phase transition of the order-disorder type. The influence of the rate and temperature of quenching, as well as the strength of an external electric field, on the subsequent evolution of the system toward the thermodynamic equilibrium state has been analyzed. It has been shown that, by varying a weak external electric field applied to the ferroelectric crystal after quenching, it is possible to obtain both single-domain and multi-domain ordered structures. It has been established that the formation of nonequilibrium ("virtual") multi-domain structures of the asymmetric type is possible for particular strengths of the electric field applied to the ferroelectric after quenching. A similar effect can be achieved by varying the depth of quenching of the sample. It has been found that, if the size of the order parameter inhomogeneities formed at the stage of quenching does not exceed a critical value, they can be reoriented partially or completely into domains of opposite sign. For this purpose, the relaxation after quenching should be performed in an external electric field of the appropriate sign.

  1. Electroweak Physics

    CERN Document Server

    Erler, Jens

    2008-01-01

    The results of high precision weak neutral current (WNC), Z-pole, and high energy collider electroweak experiments have been the primary prediction and test of electroweak unification. The electroweak program is briefly reviewed from a historical perspective. The current status and the implications for the standard model and beyond are discussed.

  2. Electroweak baryogenesis with lepton flavor violation

    Science.gov (United States)

    Chiang, Cheng-Wei; Fuyuto, Kaori; Senaha, Eibun

    2016-11-01

    We investigate the feasibility of electroweak baryogenesis in a two-Higgs doublet model with lepton flavor violation. By scrutinizing the heavy Higgs boson mass spectrum, regions satisfying both strong first-order electroweak phase transition and the muon g - 2 anomaly are identified. We also estimate the baryon number density by exploiting extra Yukawa couplings in the μ-τ sector. It is found that a CP-violating source term can be enhanced by the μ-τ flavor-violating coupling together with the extra τ coupling. With O (1) Yukawa couplings and CP-violating phases, the observed baryon number density is marginally produced under a generous assumption for the bubble wall profile.

  3. Electroweak Baryogenesis with Lepton Flavor Violation

    CERN Document Server

    Chiang, Cheng-Wei; Senaha, Eibun

    2016-01-01

    We investigate feasibility of electroweak baryogenesis with lepton flavor violation in a two-Higgs doublet model. By scrutinizing heavy Higgs boson mass spectra, regions satisfying both strong first-order electroweak phase transition and the muon $g-2$ anomaly are identified. We also estimate the baryon number density by exploiting extra Yukawa couplings in the $\\mu$-$\\tau$ sector. It is found that a CP-violating source term can be enhanced by the $\\mu$-$\\tau$ flavor-violating coupling together with the extra $\\tau$ coupling. With $\\mathcal{O}(1)$ Yukawa couplings and CP-violating phases, the observed baryon number density is marginally produced under a generous assumption on a bubble wall profile.

  4. Towards Reviving Electroweak Baryogenesis with a Fourth Generation

    Directory of Open Access Journals (Sweden)

    Wei-Shu Hou

    2013-01-01

    universe. However, it does not work within the standard model due to two reasons: (1 the strength of CP violation from the Kobayashi-Maskawa mechanism with three generations is too small; (2 the electroweak phase transition is not first order for the experimentally allowed Higgs boson mass. We discuss possibilities to solve these problems by introducing a fourth generation of fermions and how electroweak baryogenesis might be revived. We also discuss briefly the recent observation of a Higgs-like boson with mass around 125 GeV, which puts the fourth generation in a difficult situation, and the possible way out.

  5. 3-dimensional lattice studies of the electroweak phase transition at M$_{Higgs}$ $\\appprox$ 70 GeV

    CERN Document Server

    Gürtler, M; Kripfganz, J; Perlt, H; Schiller, A

    1996-01-01

    We study the electroweak phase transition by lattice simulations of an effective 3--dimensional theory, for a Higgs mass of about 70 GeV. Exploiting, among others, a variant of the equal weight criterion of phase equilibrium, we obtain transition temperature, latent heat and surface tension, and compare with M_H approx 35 GeV. In the broken phase masses and Higgs condensates are compared to perturbation theory. For the symmetric phase, bound state masses and the static force are determined.

  6. Lepton asymmetry growth in symmetric phase of electroweak plasma with hypermagnetic fields versus its washing out by sphalerons

    CERN Document Server

    Dvornikov, Maxim

    2012-01-01

    We study lepton asymmetry evolution in plasma of the early Universe before the electroweak phase transition (EWPT) accounting for chirality flip processes via Higgs decays (inverse decays) entering equilibrium at temperatures below T_RL ~ 10 TeV, T_EW T_RL. One finds a strong dependence of the asymmetries on the CS wave number. We predict a non-zero chiral asymmetry \\Delta \\mu = \\mu_e_R - \\mu_e_L \

  7. From single- to double-first-order magnetic phase transition in magnetocaloric Mn1−xCrxCoGe compounds

    NARCIS (Netherlands)

    Trung, N.T.; Biharie, V.; Zhang, L.; Caron, L.; Buschow, K.H.J.; Brück, E.H.

    2010-01-01

    Substitution of some Cr for Mn atoms in MnCoGe was employed to control the magnetic and structural transitions in this alloy to coincide, leading to a single first-order magnetostructural transition from the ferromagnetic to the paramagnetic state with a giant magnetocaloric effect observed near roo

  8. First-order formative rules

    OpenAIRE

    Fuhs, Carsten; Kop, C.

    2014-01-01

    This paper discusses the method of formative rules for first-order term rewriting, which was previously defined for a higher-order setting. Dual to the well-known usable rules, formative rules allow dropping some of the term constraints that need to be solved during a termination proof. Compared to the higher-order definition, the first-order setting allows for significant improvements of the technique.

  9. Sphalerons and the Electroweak Phase Transition in Models with Higher Scalar Representations

    CERN Document Server

    Ahriche, Amine; Nasri, Salah

    2014-01-01

    In this work we investigate the sphaleron solution in a $SU(2)\\times U(1)_X$ gauge theory, which also encompasses the Standard Model, with higher scalar representation(s) ($J^{(i)},X^{(i)}$). We show that the field profiles describing the sphaleron in higher scalar multiplet, have similar trends like the doublet case with respect to the radial distance. We compute the sphaleron energy and find that it scales linearly with the vacuum expectation value of the scalar field and its slope depends on the representation. We also investigate the effect of $U(1)$ gauge field and find that it is small for the physical value of the mixing angle, $\\theta_{W}$ and resembles the case for the doublet. For higher representations, we show that the criterion for strong first order phase transition, $v_{c}/T_{c}>\\eta$, is relaxed with respect to the doublet case, i.e. $\\eta<1$.

  10. Electroweak phase transition in the economical 3-3-1 model

    Science.gov (United States)

    Phong, Vo Quoc; Long, Hoang Ngoc; Van, Vo Thanh; Minh, Le Hoang

    2015-07-01

    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, at the TeV scale and at the 100 GeV scale. The EWPT 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 10-10 GeV. The EWPT is strengthened by only the new bosons; its strength is about 1-1.15 if the mass parts of , and are in the ranges 10-10 GeV. The contributions of and to the strengths of both EWPTs may make them sufficiently strong to provide large deviations from thermal equilibrium and B violation necessary for baryogenesis.

  11. First-Order Twistor Lifts

    Directory of Open Access Journals (Sweden)

    Simões BrunoAscenso

    2010-01-01

    Full Text Available The use of twistor methods in the study of Jacobi fields has proved quite fruitful, leading to a series of results. L. Lemaire and J. C. Wood proved several properties of Jacobi fields along harmonic maps from the two-sphere to the complex projective plane and to the three- and four-dimensional spheres, by carefully relating the infinitesimal deformations of the harmonic maps to those of the holomorphic data describing them. In order to advance this programme, we prove a series of relations between infinitesimal properties of the map and those of its twistor lift. Namely, we prove that isotropy and harmonicity to first order of the map correspond to holomorphicity to first order of its lift into the twistor space, relatively to the standard almost complex structures and . This is done by obtaining first-order analogues of classical twistorial constructions.

  12. Large low field magnetocaloric effect in first-order phase transition compound TlFe3Te3 with low-level hysteresis

    Science.gov (United States)

    Mao, Qianhui; Yang, Jinhu; Wang, Hangdong; Khan, Rajwali; Du, Jianhua; Zhou, Yuxing; Xu, Binjie; Chen, Qin; Fang, Minghu

    2016-01-01

    Magnetic refrigeration based on the magnetocaloric effect (MCE) is an environment-friendly, high-efficiency technology. It has been believed that a large MCE can be realized in the materials with a first-order magnetic transition (FOMT). Here, we found that TlFe3Te3 is a ferromagnetic metal with a first-order magnetic transition occurring at Curie temperature TC = 220 K. The maximum values of magnetic entropy change (Δ) along the crystallographic c-axis, estimated from the magnetization data, reach to 5.9 J kg−1K−1 and 7.0 J kg−1 K−1 for the magnetic field changes, ΔH = 0–1 T and 0–2 T, respectively, which is significantly larger than that of MCE materials with a second-order magnetic transition (SOMT). Besides the large ΔSM, the low-level both thermal and field hysteresis make TlFe3Te3 compound an attractive candidate for magnetic refrigeration. Our findings should inspire the exploration of high performance new MCE materials. PMID:27681203

  13. Large low field magnetocaloric effect in first-order phase transition compound TlFe3Te3 with low-level hysteresis

    Science.gov (United States)

    Mao, Qianhui; Yang, Jinhu; Wang, Hangdong; Khan, Rajwali; Du, Jianhua; Zhou, Yuxing; Xu, Binjie; Chen, Qin; Fang, Minghu

    2016-09-01

    Magnetic refrigeration based on the magnetocaloric effect (MCE) is an environment-friendly, high-efficiency technology. It has been believed that a large MCE can be realized in the materials with a first-order magnetic transition (FOMT). Here, we found that TlFe3Te3 is a ferromagnetic metal with a first-order magnetic transition occurring at Curie temperature TC = 220 K. The maximum values of magnetic entropy change (Δ) along the crystallographic c-axis, estimated from the magnetization data, reach to 5.9 J kg‑1K‑1 and 7.0 J kg‑1 K‑1 for the magnetic field changes, ΔH = 0–1 T and 0–2 T, respectively, which is significantly larger than that of MCE materials with a second-order magnetic transition (SOMT). Besides the large ΔSM, the low-level both thermal and field hysteresis make TlFe3Te3 compound an attractive candidate for magnetic refrigeration. Our findings should inspire the exploration of high performance new MCE materials.

  14. A First-Order Non-Homogeneous Markov Model for the Response of Spiking Neurons Stimulated by Small Phase-Continuous Signals

    CERN Document Server

    Tapson, J; van Schaik, A; Etienne-Cummings, R

    2008-01-01

    We present a first-order non-homogeneous Markov model for the interspike-interval density of a continuously stimulated spiking neuron. The model allows the conditional interspike-interval density and the stationary interspike-interval density to be expressed as products of two separate functions, one of which describes only the neuron characteristics, and the other of which describes only the signal characteristics. This allows the use of this model to predict the response when the underlying neuron model is not known or well determined. The approximation shows particularly clearly that signal autocorrelations and cross-correlations arise as natural features of the interspike-interval density, and are particularly clear for small signals and moderate noise. We show that this model simplifies the design of spiking neuron cross-correlation systems, and describe a four-neuron mutual inhibition network that generates a cross-correlation output for two input signals.

  15. Supersymmetric Electroweak Baryogenesis

    CERN Document Server

    Rius, N; Rius, Nuria; Sanz, Veronica

    2000-01-01

    We calculate the baryon asymmetry generated at the electroweak phase transition in the minimal supersymmetric standard model, using a new method to compute the CP-violating asymmetry in the Higgsino flux reflected into the unbroken phase. The method is based on a Higgs insertion expansion. We find that the CP asymmetry at leading order is proportional to the change in $\\tan next-to-leading order this suppression factor disappears. These results explain previous discrepancies among different calculations, and may enhance the final baryon asymmetry generated during the electroweak phase transition.

  16. 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.)

  17. Search for the First-Order Liquid-to-Liquid Phase Transition in Low-Temperature Confined Water by Neutron Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Sow-Hsin [Massachusetts Institute of Technology (MIT); Wang, Zhe [Massachusetts Institute of Technology (MIT); Kolesnikov, Alexander I [ORNL; Zhang, Yang [ORNL; Liu, Kao-Hsiang [National Taiwan University

    2013-01-01

    It has been conjectured that a 1st order liquid-to-liquid (L-L) phase transition (LLPT) between high density liquid (HDL) and low density liquid (LDL) in supercooled water may exist, as a thermodynamic extension to the liquid phase of the 1st order transition established between the two bulk solid phases of amorphous ice, the high density amorphous ice (HDA) and the low density amorphous ice (LDA). In this paper, we first recall our previous attempts to establish the existence of the 1st order L-L phase transition through the use of two neutron scattering techniques: a constant Q elastic diffraction study of isobaric temperature scan of the D2O density, namely, the equation of state (EOS) measurements. A pronounced density hysteresis phenomenon in the temperature scan of the density above P = 1500 bar is observed which gives a plausible evidence of crossing the 1st order L-L phase transition line above this pressure; an incoherent quasi-elastic scattering measurements of temperature-dependence of the alpha-relaxation time of H2O at a series of pressures, namely, the study of the Fragile-to-Strong dynamic crossover (FSC) phenomenon as a function of pressure which we interpreted as the results of crossing the Widom line in the one-phase region. In this new experiment, we used incoherent inelastic neutron scattering (INS) to measure the density of states (DOS) of H atoms in H2O molecules in confined water as function of temperature and pressure, through which we may be able to follow the emergence of the LDL and HDL phases at supercooled temperature and high pressures. We here report for the first time the differences of librational and translational DOSs between the hypothetical HDL and LDL phases, which are similar to the corresponding differences between the well-established HDA and LDA ices. This is plausible evidence that the HDL and LDL phases are the thermodynamic extensions of the corresponding amorphous solid water HDA and LDA ices.

  18. A first order Tsallis theory

    Science.gov (United States)

    Ferri, Gustavo L.; Plastino, Angel; Rocca, Mario C.; Zamora, Dario J.

    2017-03-01

    We investigate first-order approximations to both (i) Tsallis' entropy Sq and (ii) the Sq-MaxEnt solution (called q-exponential functions eq). We use an approximation/expansion for q very close to unity. It is shown that the functions arising from the procedure (ii) are the MaxEnt solutions to the entropy emerging from (i). Our present treatment is motivated by the fact it is FREE of the poles that, for classic quadratic Hamiltonians, appear in Tsallis' approach, as demonstrated in [A. Plastimo, M.C. Rocca, Europhys. Lett. 104, 60003 (2013)]. Additionally, we show that our treatment is compatible with extant date on the ozone layer.

  19. Enabling Electroweak Baryogenesis through Dark Matter

    CERN Document Server

    Lewicki, Marek; Wells, James D

    2016-01-01

    We study the impact on electroweak baryogenesis from a swifter cosmological expansion induced by dark matter. We detail the experimental bounds that one can place on models that realize it, and we investigate the modifications of these bounds that result from a non-standard cosmological history. The modifications can be sizeable if the expansion rate of the Universe increases by several orders of magnitude. We illustrate the impact through the example of scalar field dark matter, which can alter the cosmological history enough to enable a strong-enough first-order phase transition in the Standard Model when it is supplemented by a dimension six operator directly modifying the Higgs boson potential. We show that due to the modified cosmological history, electroweak baryogenesis can be realized, while keeping deviations of the triple Higgs coupling below HL-LHC sensitivies. The required scale of new physics to effectuate a strong-enough first order phase transition can change by as much as twenty percent as the...

  20. First order phase transition in deuterated triglycine selenate under an electric field: experimental study and analysis in the frame of Landau theory

    Energy Technology Data Exchange (ETDEWEB)

    Romero, F J; Gallardo, M C; Del Cerro, J [Departamento de Fisica de la Materia Condensada, Instituto Mixto de Ciencia de Materiales CSIC-Universidad de Sevilla, Apartado 1065, 41080 Sevilla (Spain)], E-mail: fjromero@us.es

    2009-04-15

    The influence of electric fields lower than the critical field in the ferroelectric phase transition in deuterated triglycine selenate has been studied by means of thermal and dielectric properties. The latent heat, specific heat and dielectric constant have been measured and compared to the theoretical expectations from the Landau theory under an electric field. A full agreement has been found on cooling experiments.

  1. First-Order Logical Duality

    CERN Document Server

    Awodey, Steve

    2010-01-01

    From a logical point of view, Stone duality for Boolean algebras relates theories in classical propositional logic and their collections of models. The theories can be seen as presentations of Boolean algebras, and the collections of models can be topologized in such a way that the theory can be recovered from its space of models. The situation can be cast as a formal duality relating two categories of syntax and semantics, mediated by homming into a common dualizing object, in this case $2$. In the present work, we generalize the entire arrangement from propositional to first-order logic. Boolean algebras are replaced by Boolean categories presented by theories in first-order logic, and spaces of models are replaced by topological groupoids of models and their isomorphisms. A duality between the resulting categories of syntax and semantics, expressed first in the form of a contravariant adjunction, is established by homming into a common dualizing object, now $\\Sets$, regarded once as a boolean category, and...

  2. First-Order Hybrid Logic

    DEFF Research Database (Denmark)

    Braüner, Torben

    2011-01-01

    Hybrid logic is an extension of modal logic which allows us to refer explicitly to points of the model in the syntax of formulas. It is easy to justify interest in hybrid logic on applied grounds, with the usefulness of the additional expressive power. For example, when reasoning about time one...... often wants to build up a series of assertions about what happens at a particular instant, and standard modal formalisms do not allow this. What is less obvious is that the route hybrid logic takes to overcome this problem often actually improves the behaviour of the underlying modal formalism....... For example, it becomes far simpler to formulate proof-systems for hybrid logic, and completeness results can be proved of a generality that is simply not available in modal logic. That is, hybridization is a systematic way of remedying a number of known deficiencies of modal logic. First-order hybrid logic...

  3. Exact diagonalization for spin-1/2 chains and the first order quantum phase transitions of the XXX chain in a uniform transverse field

    Energy Technology Data Exchange (ETDEWEB)

    Pan Feng [Department of Physics, Liaoning Normal University, Dalian 116029 (China); Guan Xin [Department of Physics, Liaoning Normal University, Dalian 116029 (China); Ma Nan [Department of Physics, Liaoning Normal University, Dalian 116029 (China); Han Wenjuan [Department of Physics, Liaoning Normal University, Dalian 116029 (China); Draayer, J P [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States)

    2007-09-26

    A simple Mathematica code based on the differential realization of hard-core boson operators for finding exact solutions of the periodic-N spin-1/2 systems with or beyond nearest neighbor interactions is proposed; it can easily be used to study general spin-1/2 interaction systems. As an example, the code is applied to study XXX spin-1/2 chains with nearest neighbor interaction in a uniform transverse field. It shows that there are [N/2] level-crossing points in the ground state, where N is the periodic number of the system and [x] stands for the integer part of x, when the interaction strength and magnitude of the magnetic field satisfy certain conditions. The quantum phase transitional behavior in the ground state of the system in the thermodynamic limit is also studied.

  4. Hot electroweak matter

    OpenAIRE

    Kajantie, K.

    1994-01-01

    This talk summarises recent results on lattice Monte Carlo studies of finite T electroweak phase transition. Particular attention is given to the 3d effective theory approach, replacing the full 4d theory by a three dimensional effective theory of the modes constant in imaginary time.

  5. Phase-space analysis for fractional Fourier transform of first-order optical system%一阶光学系统分数傅里叶变换的相空间分析

    Institute of Scientific and Technical Information of China (English)

    潘卫清; 朱勇建; 王建中

    2009-01-01

    在维格纳相空间中,通过将一阶光学系统的传输矩阵分解为坐标旋转、比例缩放和啁啾矩阵的组合,得到了一阶光学系统在空域的分数傅里叶表示.结果表明:任意一阶光学系统均可表示为经过比例缩放和二次相位调制的分数傅里叶变换.通过将输入输出光场在相空间中作π/2角旋转,得到了一阶光学系统在频域的传输矩阵和衍射积分公式,进而得到了一阶光学系统在频域的分数傅里叶表示.比较空域和频域一阶光学系统的相空间变换矩阵,说明2个系统本质上属同一变换在不同基坐标下的表示,并推导出了光学系统在空域和频域具有相同分数傅里叶变换的条件.%The fractional Fourier express of the first-order optical system was derived by decomposing the transfer matrices of firstorder optical system into coordinate rotation matrix, scale matrix and chirp matrix in Wigner phase space. The results show that an arbitrary first-order optical system can be expressed as the scaled and chirp modulation fractional Fourier transform. The transfer matrix and diffractive integral formula in frequency domain were acquired by rotating the input and output optical field π/2 in the phase space. Accordingly the fractional Fourier transforms of a first-order optical system in frequency domain were also obtained. By comparing the transfer matrices of two first-order optical systems in space and frequency domains respectively, it is found that the two first-order optical systems in different domain can be expressed as two different expressions of one and the same transfer based on different coordinates. At last the condition is derived for an optical system to implement the fractional Fourier transform in space and frequency domains with the same order.

  6. Kinetic arrest of first-order transition between charge-ordered and ferromagnetic phases in Gd0.5Sr0.5MnO3 single crystals: magnetization relaxation studies

    Science.gov (United States)

    Wagh, Aditya A.; Kumar, P. S. Anil; Elizabeth, Suja

    2016-10-01

    We have studied the span and nature of first-order phase transition (FOPT) between charge-ordered insulating and ferromagnetic metallic phases in oriented single crystals of Gd0.5Sr0.5MnO3. Magnetic field—temperature phase diagram was formulated from magnetization data for different crystallographic axes and non-monotonic variation of supercooling limit was observed at low temperature. A peculiar nature of magnetization was observed as irreversible open hysteresis loops during thermal cycling. We perceive that the nature of metastable states responsible for open hysteresis loops is different from that of supercooled ones. Further, thermal cycling magnetization data reveal that magnetic phases formed at 8 K after zero-field or field-cooled protocols (89 kOe) are not in equilibrium. Relaxation time constant is found to increase below 30 K in magnetization relaxation measurements made across the FOPT. The non-monotonic variation of relaxation time constant is a manifestation of kinetic arrest of the FOPT. We propose that the non-equilibrium, glass-like magnetic phase (at 8 K and 89 kOe) is a consequence of kinetic arrest.

  7. Temperature-induced reversible first-order single crystal to single crystal phase transition in Boc-γ(4)(R)Val-Val-OH: interplay of enthalpy and entropy.

    Science.gov (United States)

    Pal, Rumpa; Reddy, M B Madhusudana; Dinesh, Bhimareddy; Balaram, Padmanabhan; Guru Row, Tayur N

    2014-10-01

    Crystals of Boc-γ(4)(R)Val-Val-OH undergo a reversible first-order single crystal to single crystal phase transition at Tc ≈ 205 K from the orthorhombic space group P22121 (Z' = 1) to the monoclinic space group P21 (Z' = 2) with a hysteresis of ∼2.1 K. The low-temperature monoclinic form is best described as a nonmerohedral twin with ∼50% contributions from its two components. The thermal behavior of the dipeptide crystals was characterized by differential scanning calorimetry experiments. Visual changes in birefringence of the sample during heating and cooling cycles on a hot-stage microscope with polarized light supported the phase transition. Variable-temperature unit cell check measurements from 300 to 100 K showed discontinuity in the volume and cell parameters near the transition temperature, supporting the first-order behavior. A detailed comparison of the room-temperature orthorhombic form with the low-temperature (100 K) monoclinic form revealed that the strong hydrogen-bonding motif is retained in both crystal systems, whereas the non-covalent interactions involving side chains of the dipeptide differ significantly, leading to a small change in molecular conformation in the monoclinic form as well as a small reorientation of the molecules along the ac plane. A rigid-body thermal motion analysis (translation, libration, screw; correlation of translation and libration) was performed to study the crystal entropy. The reversible nature of the phase transition is probably the result of an interplay between enthalpy and entropy: the low-temperature monoclinic form is enthalpically favored, whereas the room-temperature orthorhombic form is entropically favored.

  8. Decoupling Property of SUSY Extended Higgs Sectors and Implication for Electroweak Baryogenesis

    CERN Document Server

    Kanemura, Shinya; Shindou, Tetsuo

    2012-01-01

    One-loop contributions to the Higgs potential at finite temperatures are discussed in the supersymmetric standard model with four Higgs doublet chiral superfields as well as a pair of charged singlet chiral superfields. The mass of the lightest Higgs boson $h$ is determined only by the D-term at the tree-level in this model, while the triple Higgs boson coupling for $hhh$ can receive a significant radiative correction. The same nondecoupling effect can also contribute to realize the sufficient first order electroweak phase transition, which is required for a successful scenario of electroweak baryogenesis. This model can be a new candidate for a model in which the baryon asymmetry of the Universe is explained at the electroweak scale. We also discuss the implication for the measurement of the triple Higgs boson coupling at the ILC.

  9. Quantum statistical model of nuclear multifragmentation in the canonical ensemble method 24.60.-k; 24.60.Ky; 25.70.Pq; 25.70.-z; Nuclear multifragmentation; First-order phase transition; Quantum statistics; Canonical ensemble

    CERN Document Server

    Parvan, A S; Ploszajczak, M

    2000-01-01

    A quantum statistical model of nuclear multifragmentation is proposed. The recurrence equation method used within the canonical ensemble makes the model solvable and transparent to physical assumptions and allows to get results without involving the Monte Carlo technique. The model exhibits the first-order phase transition. Quantum statistics effects are clearly seen on the microscopic level of occupation numbers but are almost washed out for global thermodynamic variables and the averaged observables studied. In the latter case, the recurrence relations for multiplicity distributions of both intermediate-mass and all fragments are derived and the specific changes in the shape of multiplicity distributions in the narrow region of the transition temperature is stressed. The temperature domain favorable to search for the HBT effect is noted.

  10. Effects of Additive Noise on First-Order-Like Phase Transition in a Laser System%加性噪声对激光一级相变类比的影响

    Institute of Scientific and Technical Information of China (English)

    胡静; 朱士群

    2001-01-01

    从单模激光场的增益噪声模型出发,导出了激光场定态强度分布函数,研究了定态分布函数的极值点随加性噪声、乘性噪声和注入信号的变化情况。结果表明,乘性噪声是使激光系统出现一级相变类比的关键因素,注入信号使相变行为减弱,而加性噪声却使得定态分布中极值点的数量和位置出现来回跳跃式变化。%The steady state intensity distribution function is derived froma single mode gain-noise laser model. The extrema of the steady state distribution function is investigated as the additive noise, multiplicative noise and injected signal are changing. It is shown that the multiplicative noise plays a key rule in the first-order-like phase transition in a laser system. The injected signal can reduce the phase transition. The additive noise causes the number and locations of the extrema in the steady state distribution function jumping back and forth.

  11. Studies on magnetic-field-induced first-order transitions

    Indian Academy of Sciences (India)

    P Chaddah

    2006-07-01

    We shall discuss magnetization and transport measurements in materials exhibiting a broad first-order transition. The phase transitions would be caused by varying magnetic field as well as temperature, and we concentrate on ferro- to antiferromagnetic transitions in magnetic materials. We distinguish between metastable supercooled phases and metastable glassy phase.

  12. 一级相变磁制冷材料的基础问题探究%Basic problem in the first-order phase transition magnetic refrigeration material

    Institute of Scientific and Technical Information of China (English)

    陈湘; 陈云贵; 唐永柏; 肖定全; 李道华

    2014-01-01

    由于一级相变磁制冷材料发生磁相变时有晶胞体积的突变,相变过程中有相变潜热存在,其磁化过程中有许多磁学问题有待于进一步探究。本文以LaFe13-xSix合金为研究对象,在现有对磁一级相变基础问题的分析基础上,对一级相变材料中系统熵变、等温熵变、绝热温变、热滞、磁滞、铁磁与顺磁态两相共存的温度区间和磁场区间、制冷能力的计算等磁学基础问题进行了较为细致的探究。分析表明,在忽略完全铁磁态和顺磁态对磁热效应的贡献时, Maxwell 方程和Clausius-Clapeyron 方程计算熵变的值具有等效性。等温磁化过程中升温和降温曲线包围的面积SABCE (磁滞的大小),实际上是升温过程和降温过程中磁场做的净功,等于相变潜热之差。磁滞和热滞的大小与磁化过程数据测量的时间有关,测量时间越长则滞后越小,当相变是平衡相变则滞后为零。另外,对温度和磁场诱导磁相变过程进行了分析,提出了一级相变磁制冷材料制冷能力的不同计算模型。本文对一级相变磁制冷材料的磁学基础问题研究有一定的参考价值。%Due to the cell volume mutations and the phase transition latent heat existing during phase transition of the first-order phase transition magnetic refrigeration material, many basic problems need to further explore in the magneti-zation process. In this paper, taking LaFe13-xSixalloys as the research object, we discuss in detail some problems, such as a phase-change, entropy change, isothermal entropy change, adiabatic temperature change, thermal and magnetic hysteresis, the temperature range and magnetic field range in which the ferromagnetic and paramagnetic state coexist, and magnetic refrigeration capacity calculation, The analysis shows that the magnetic entropies calculated by Maxwell equation and Clausius-Clapeyron equation are equivalent when neglecting the

  13. An Adequate First Order Logic of Intervals

    DEFF Research Database (Denmark)

    Chaochen, Zhou; Hansen, Michael Reichhardt

    1998-01-01

    This paper introduces left and right neighbourhoods as primitive interval modalities to define other unary and binary modalities of intervals in a first order logic with interval length. A complete first order logic for the neighbourhood modalities is presented. It is demonstrated how the logic c...

  14. Chemical Dosing and First-Order Kinetics

    Science.gov (United States)

    Hladky, Paul W.

    2011-01-01

    College students encounter a variety of first-order phenomena in their mathematics and science courses. Introductory chemistry textbooks that discuss first-order processes, usually in conjunction with chemical kinetics or radioactive decay, stop at single, discrete dose events. Although single-dose situations are important, multiple-dose events,…

  15. First-order Dyson coordinates and geometry.

    Science.gov (United States)

    Hermes, Matthew R; Hirata, So

    2013-08-15

    The mathematical constructs of the Dyson coordinates and geometry are introduced. The former are a unitary transformation of the normal coordinates and the anharmonic vibrational counterpart of the Dyson orbitals in electronic structure theory. The first-order Dyson coordinates bring the sums of the harmonic force constants and their first-order diagrammatic perturbation corrections (the first-order Dyson self-energy) to a diagonal form. The first-order Dyson geometry has no counterpart in electronic structure theory. It is the point on the potential energy surface at which the sums of the energy gradients and their first-order diagrammatic perturbation corrections vanish. It agrees with the vibrationally averaged geometry of vibrational self-consistent field (VSCF) theory in the bulk limit. These constructs provide a unified view of the relationship of VSCF and its diagrammatically size-consistent modifications as well as the self-consistent phonon method widely used in solid-state physics.

  16. MAGNETIC FIELD INDUCED FIRST-ORDER TRANSITIONS IN DYSPROSIUM ORTHOFERRITE

    OpenAIRE

    Eremenko, V.; Gnatchenko, S.; Kharchenko, N.; Lebedev, P.; Piotrowski, K; Szymczak, H.; Szymczak, R.

    1988-01-01

    New type of magnetic first-order phase transition induced by external magnetic field applied in the ab-plane in DyFeO3 is investigated using different magnetooptic techniques. The phenomenological model of this transition is proposed. The phase diagram in H-T plane has been obtained for various H orientation in the ab-plane.

  17. Electroweak physics at the LHC

    Science.gov (United States)

    Berryhill, J.; Oh, A.

    2017-02-01

    The Large Hadron Collider (LHC) has completed in 2012 its first running phase and the experiments have collected data sets of proton-proton collisions at center-of-mass energies of 7 and 8 TeV with an integrated luminosity of about 5 and 20 {{fb}}-1, respectively. Analyses of these data sets have produced a rich set of results in the electroweak sector of the standard model. This article reviews the status of electroweak measurements of the ATLAS, CMS and LHCb experiments at the LHC.

  18. Y-doped La{sub 0.7}Ca{sub 0.3}MnO{sub 3} manganites exhibiting a large magnetocaloric effect and the crossover of first-order and second-order phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Phan, The-Long; Jung, C. U.; Lee, B. W., E-mail: bwlee@hufs.ac.kr [Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin 449-791 (Korea, Republic of); Ho, T. A.; Manh, T. V. [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Dang, N. T. [Institute of Research and Development, Duy Tan University, Da Nang (Viet Nam); Thanh, T. D. [Institute of Materials Science, Vietnam Academy of Science and Technology, Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam)

    2015-10-14

    We prepared orthorhombic La{sub 0.7−x}Y{sub x}Ca{sub 0.3}MnO{sub 3} samples (x = 0, 0.04, 0.06, and 0.08) by conventional solid-state reaction and then studied their magnetic properties and magnetocaloric (MC) effect based on magnetization versus temperature and magnetic-field measurements, M(T, H). The experimental results revealed that an x increase in La{sub 0.7−x}Y{sub x}Ca{sub 0.3}MnO{sub 3} reduced the ferromagnetic-paramagnetic transition temperature (T{sub C}) from 260 K (for x = 0) to ∼126 K (for x = 0.08). Around the T{sub C}, maximum magnetic-entropy changes for a magnetic-field variation interval H = 50 kOe are about 10.7, 8.5, 7.4, and 5.8 J·kg{sup −1}·K{sup −1} for x = 0, 0.04, 0.06, and 0.08, respectively, corresponding to refrigerant capacities RC = 250–280 J·kg{sup −1}. These values are comparable to those of some conventional MC materials, revealing the applicability of La{sub 0.7−x}Y{sub x}Ca{sub 0.3}MnO{sub 3} in magnetic refrigeration. Using the Arrott method and scaling hypothesis as analyzing high-field M(H, T) data, and the universal-curve construction of the magnetic entropy change, we found a magnetic-phase separation. While the samples x = 0−0.06 exhibit a first-order magnetic phase transition, x = 0.08 exhibits the crossover of the first-to-second-order phase transformation (with its critical-exponent values close to those expected for the tricritical mean-field theory) and has the presence of ferromagnetic clusters even above the T{sub C}. Such the variations in the magnetism and MC effect are related to the changes in structural parameters caused by the Y substitution for La because Y doping does not change the concentration ratio of Mn{sup 3+}/Mn{sup 4+}.

  19. Resonant di-Higgs boson production in the b b ¯ W channel: Probing the electroweak phase transition at the LHC

    Science.gov (United States)

    Huang, T.; No, J. M.; Pernié, L.; Ramsey-Musolf, M.; Safonov, A.; Spannowsky, M.; Winslow, P.

    2017-08-01

    We analyze the prospects for resonant di-Higgs production searches at the LHC in the b b ¯W+W- (W+→ℓ+νℓ, W-→ℓ-ν¯ℓ) channel, as a probe of the nature of the electroweak phase transition in Higgs portal extensions of the Standard Model. In order to maximize the sensitivity in this final state, we develop a new algorithm for the reconstruction of the b b ¯W+W- invariant mass in the presence of neutrinos from the W decays, building from a technique developed for the reconstruction of resonances decaying to τ+τ- pairs. We show that resonant di-Higgs production in the b b ¯W+W- channel could be a competitive probe of the electroweak phase transition already with the data sets to be collected by the CMS and ATLAS experiments in run 2 of the LHC. The increase in sensitivity with larger amounts of data accumulated during the high-luminosity LHC phase can be sufficient to enable a potential discovery of the resonant di-Higgs production in this channel.

  20. Monopole annihilation at the electroweak scale

    CERN Document Server

    Terning, J

    1992-01-01

    We examine the issue of monopole annihilation at the electroweak scale induced by flux tube confinement, concentrating first on the simplest possibility---one which requires no new physics beyond the standard model. Monopoles existing at the time of the electroweak phase transition may trigger $W$ condensation which can confine magnetic flux into flux tubes. However we show on very general grounds, using several independent estimates, that such a mechanism is impotent. We then present several general dynamical arguments constraining the possibility of monopole annihilation through any confining phase near the electroweak scale.

  1. First-order partial differential equations

    CERN Document Server

    Rhee, Hyun-Ku; Amundson, Neal R

    2001-01-01

    Second volume of a highly regarded two-volume set, fully usable on its own, examines physical systems that can usefully be modeled by equations of the first order. Examples are drawn from a wide range of scientific and engineering disciplines. The book begins with a consideration of pairs of quasilinear hyperbolic equations of the first order and goes on to explore multicomponent chromatography, complications of counter-current moving-bed adsorbers, the adiabatic adsorption column, and chemical reaction in countercurrent reactors. Exercises appear at the end of most sections. Accessible to any

  2. Symmetries and first order ODE patterns

    Science.gov (United States)

    Cheb-Terrab, E. S.; Roche, A. D.

    1998-10-01

    A scheme for determining symmetries for certain families of first order ODEs, without solving any differential equations, and based mainly in matching an ODE to patterns of invariant ODE families, is presented. The scheme was implemented in Maple, in the framework of the ODEtools package and its ODE-solver. A statistics of the performance of this approach in solving the first order ODE examples of Kamke's book (E. Kamke, Differentialgleichungen: Lösungsmethoden und Lösungen (Chelsea, New York, 1959)) is shown.

  3. A definability theorem for first order logic

    NARCIS (Netherlands)

    Butz, C.; Moerdijk, I.

    2001-01-01

    In this paper we will present a definability theorem for first order logic This theorem is very easy to state and its proof only uses elementary tools To explain the theorem let us first observe that if M is a model of a theory T in a language L then clearly any definable subset S M ie a subset S

  4. First-Order Logic According to Harrison

    DEFF Research Database (Denmark)

    Jensen, Alexander Birch; Schlichtkrull, Anders; Villadsen, Jørgen

    2017-01-01

    We present a certified declarative first-order prover with equality based on John Harrison’s Handbook of Practical Logic and Automated Reasoning, Cambridge University Press, 2009. ML code reflection is used such that the entire prover can be executed within Isabelle as a very simple interactive...

  5. Hearing the echoes of electroweak baryogenesis with gravitational wave detectors

    Science.gov (United States)

    Huang, Fa Peng; Wan, Youping; Wang, Dong-Gang; Cai, Yi-Fu; Zhang, Xinmin

    2016-08-01

    We report on the first joint analysis of observational signatures from the electroweak baryogenesis in both gravitational wave (GW) detectors and particle colliders. With an effective extension of the Higgs sector in terms of the dimension-six operators, we derive a strong first-order phase transition associated with a sizable CP violation to realize a successful electroweak baryogenesis. We calculate the GW spectrum resulting from the bubble nucleation, plasma transportation, and magnetohydrodynamic turbulence of this process that occurred after the big bang and find that it yields GW signals testable with the Evolved Laser Interferometer Space Antenna, Deci-hertz Interferometer Gravitational Wave Observatory, and Big Bang Observer. We further identify collider signals from the same mechanism that are observable at the planning Circular Electron Positron Collider. Our analysis bridges astrophysics and cosmology with particle physics by providing significant motivation for searches for GW events peaking at the (1 0-4,1 ) Hz range, which are associated with signals at colliders, and highlights the possibility of an interdisciplinary observational window into baryogenesis. The technique applied in analyzing early Universe phase transitions may enlighten the study of phase transitions in applied science.

  6. Degenerate spacetimes in first order gravity

    CERN Document Server

    Kaul, Romesh K

    2016-01-01

    We present a systematic framework to obtain the most general solutions of the equations of motion in first order gravity theory with degenerate tetrads. There are many possible solutions. Generically, these exhibit non-vanishing torsion even in the absence of any matter coupling. These solutions are shown to contain a special set of eight configurations which are associated with the homogeneous model three-geometries of Thurston.

  7. First-order partial differential equations

    CERN Document Server

    Rhee, Hyun-Ku; Amundson, Neal R

    2001-01-01

    This first volume of a highly regarded two-volume text is fully usable on its own. After going over some of the preliminaries, the authors discuss mathematical models that yield first-order partial differential equations; motivations, classifications, and some methods of solution; linear and semilinear equations; chromatographic equations with finite rate expressions; homogeneous and nonhomogeneous quasilinear equations; formation and propagation of shocks; conservation equations, weak solutions, and shock layers; nonlinear equations; and variational problems. Exercises appear at the end of mo

  8. Multipoint normal differential operators of first order

    Directory of Open Access Journals (Sweden)

    Zameddin I. Ismailov

    2009-01-01

    Full Text Available In this paper we discuss all normal extensions of a minimal operator generated by a linear multipoint differential-operator expression of first order in the Hilbert space of vector-functions on the finite interval in terms of boundary and interior point values. Later on, we investigate the structure of the spectrum, its discreteness and the asymptotic behavior of the eigenvalues at infinity for these extensions.

  9. Continuous first order logic and local stability

    CERN Document Server

    Yaacov, Itaï Ben

    2008-01-01

    We develop continuous first order logic, a variant of the logic described in \\cite{Chang-Keisler:ContinuousModelTheory}. We show that this logic has the same power of expression as the framework of open Hausdorff cats, and as such extends Henson's logic for Banach space structures. We conclude with the development of local stability, for which this logic is particularly well-suited.

  10. Intuitionistic Completeness of First-Order Logic

    CERN Document Server

    Constable, Robert

    2011-01-01

    We establish completeness for intuitionistic first-order logic, iFOL, showing that is a formula is provable if and only if it is uniformly valid under the Brouwer Heyting Kolmogorov (BHK) semantics, the intended semantics of iFOL. Our proof is intuitionistic and provides an effective procedure Prf that converts uniform evidence into a formal first-order proof. We have implemented Prf . Uniform validity is defined using the intersection operator as a universal quantifier over the domain of discourse and atomic predicates. Formulas of iFOL that are uniformly valid are also intuitionistically valid, but not conversely. Our strongest result requires the Fan Theorem; it can also be proved classically by showing that Prf terminates using K\\"onig's Theorem. The fundamental idea behind our completeness theorem is that a single evidence term evd witnesses the uniform validity of a minimal logic formula F. Finding even one uniform realizer guarantees validity because Prf (F, evd) builds a first-order proof of F, establ...

  11. Geometry of Lagrangian First-order Classical Field Theories

    CERN Document Server

    Echeverría-Enríquez, A; Román-Roy, N; Echeverr\\'ia-Enr\\'iquez, Arturo; Muñoz-Lecanda, Miguel C.; Román-Roy, Narciso

    1996-01-01

    We construct a lagrangian geometric formulation for first-order field theories using the canonical structures of first-order jet bundles, which are taken as the phase spaces of the systems in consideration. First of all, we construct all the geometric structures associated with a first-order jet bundle and, using them, we develop the lagrangian formalism, defining the canonical forms associated with a lagrangian density and the density of lagrangian energy, obtaining the {\\sl Euler-Lagrange equations} in two equivalent ways: as the result of a variational problem and developing the {\\sl jet field formalism} (which is a formulation more similar to the case of mechanical systems). A statement and proof of Noether's theorem is also given, using the latter formalism. Finally, some classical examples are briefly studied.

  12. Novel SVPWM based on first order equation

    Directory of Open Access Journals (Sweden)

    Ahmed A. Mansour

    2015-09-01

    Full Text Available PWM plays an important role in generating sinusoidal waveform for variable voltage variable frequency drives (VVVFD's with a minimum harmonic level. PWM techniques have many methods in implementation ranging from a relatively simple method such as modulating sine wave to the advanced Space Vector PWM technique SVPWM. The SVPWM has a dense calculation that requires considerable processor time for execution. The proposed technique requires simple calculations and can be implemented using simple microcontrollers. The calculations of the proposed SVPWM are based on first order equations rather than trigonometric functions requiring either huge lookup tables for fetching or too many instruction cycles for calculation on a digital controller.

  13. Meshfree First-order System Least Squares

    Institute of Scientific and Technical Information of China (English)

    Hugh R.MacMillan; Max D.Gunzburger; John V.Burkardt

    2008-01-01

    We prove convergence for a meshfree first-order system least squares (FOSLS) partition of unity finite element method (PUFEM). Essentially, by virtue of the partition of unity, local approximation gives rise to global approximation in H(div)∩ H(curl). The FOSLS formulation yields local a posteriori error estimates to guide the judicious allotment of new degrees of freedom to enrich the initial point set in a meshfree dis-cretization. Preliminary numerical results are provided and remaining challenges are discussed.

  14. Electroweak Results from CMS

    CERN Document Server

    CERN. Geneva

    2016-01-01

    We present recent CMS measurements on electroweak boson production including single, double, and triple boson final states. Electroweak processes span many orders of magnitude in production cross section. Measurements of high-rate processes provide stringent tests of the standard model. In addition, rare triboson proceses and final states produced through vector boson scattering are newly accessible with the large integrated luminosity provided by the LHC. If new physics lies just beyond the reach of the LHC, its effects may manifest as enhancements to the high energy kinematics in mulitboson production. We present limits on new physics signatures using an effective field theory which models these modifications as modifications of electroweak gauge couplings. Since electroweak measurements will continue to benefit from the increasing integrated luminosity provided by the LHC, the future prospects of electroweak physics are discussed.

  15. First order gravity on the light front

    CERN Document Server

    Alexandrov, Sergei

    2014-01-01

    We study the canonical structure of the real first order formulation of general relativity on a null foliation. We use a tetrad decomposition which allows to elegantly encode the nature of the foliation in the norm of a vector in the fibre bundle. The resulting constraint structure shows some peculiarities. In particular, the dynamical Einstein equations propagating the physical degrees of freedom appear in this formalism as second class tertiary constraints, which puts them on the same footing as the Hamiltonian constraint of the Ashtekar's connection formulation. We also provide a framework to address the issue of zero modes in gravity, in particular, to study the non-perturbative fate of the zero modes of the linearized theory. Our results give a new angle on the dynamics of general relativity and can be used to quantize null hypersurfaces in the formalism of loop quantum gravity or spin foams.

  16. Total variation projection with first order schemes.

    Science.gov (United States)

    Fadili, Jalal M; Peyre, Gabriel

    2011-03-01

    This article proposes a new algorithm to compute the projection on the set of images whose total variation is bounded by a constant. The projection is computed through a dual formulation that is solved by first order non-smooth optimization methods. This yields an iterative algorithm that applies iterative soft thresholding to the dual vector field, and for which we establish convergence rate on the primal iterates. This projection algorithm can then be used as a building block in a variety of applications such as solving inverse problems under a total variation constraint, or for texture synthesis. Numerical results are reported to illustrate the usefulness and potential applicability of our TV projection algorithm on various examples including denoising, texture synthesis, inpainting, deconvolution and tomography problems. We also show that our projection algorithm competes favorably with state-of-the-art TV projection methods in terms of convergence speed.

  17. Electroweak baryogenesis in a scalar-assisted vectorlike fermion model

    Science.gov (United States)

    Xiao, Ming-Lei; Yu, Jiang-Hao

    2016-07-01

    We extend the standard model to a scalar-assisted vectorlike fermion model to realize electroweak baryogenesis. The extended Cabibbo-Kobayashi-Maskawa matrix, due to the mixing among the vectorlike quark and the standard model quarks, provides additional sources of the C P violation. Together with the enhancement from a large vectorlike quark mass, a large enough baryon-to-photon ratio could be obtained. The strongly first-order phase transition could be realized via the potential barrier which separates the broken minimum and the symmetric minimum in the scalar potential. We investigate in detail the one loop temperature-dependent effective potential and perform a random parameter scan to study the allowed parameter region that satisfies the strongly first order phase transition criteria vc≥Tc. Several distinct patterns of phase transition are classified and discussed. Among these patterns, a large trilinear mass term between the Higgs boson and the scalar is preferred, for it controls the width of the potential barrier. Our results indicate large quartic scalar couplings and a moderate mixing angle between the Higgs boson and the new scalar. This parameter region could be further explored at the Run 2 LHC.

  18. Electroweak Baryogenesis in a Vector-like Fermion Model

    CERN Document Server

    Xiao, Ming-Lei

    2015-01-01

    We extend the standard model to a scalar-assisted vector-like fermion model to realize electroweak baryogenesis. The extended Cabbibo-Kobayashi-Maskawa matrix, due to the mixing among the vector-like quark and the standard model quarks, provides additional sources of the CP violation. Together with the enhancement from large vector-like quark mass, a large enough baryon-to-photon ratio could be obtained. We investigate in detail the one-loop temperature-dependent effective potential involving the Higgs field $\\phi$ and a new singlet scalar field $s$ in the on-shell scheme. The scalar potential could generate either a tree-level or a thermally-induced barrier to separate the broken minimum and the symmetric minimum, and thus realize the first order phase transition through bubble nucleation. We perform a random parameter scan and study the allowed parameter region that satisfy the strong first order phase transition criteria $v_c \\ge T_c$. According to the distinct features of the phase transition in the two-d...

  19. Instantons and surface tension at a first-order transition

    Science.gov (United States)

    Gupta, Sourendu

    1994-04-01

    We study the dynamics of the first-order phase transition in the two-dimensional 15-state Potts model, both at and off equilibrium. We find that phase changes take place through nucleation in both cases, and finite volume effects are described well through an instanton computation. Thus a dynamical measurement of the surface tension is possible. We find that the order-disorder surface tension is compatible with perfect wetting. An accurate treatment of fluctuations about the instanton solution is seen to be of great importance. Current Address: Theory Group, TIFR, Homi Bhabha Road, Bombay 400005, India.

  20. Disfavouring Electroweak Baryogenesis and a hidden Higgs in a CP-violating Two-Higgs-Doublet Model

    CERN Document Server

    Haarr, Anders; Petersen, Troels C

    2016-01-01

    A strongly first-order electroweak phase transition is a necessary requirement for Electroweak Baryogenesis. We investigate the plausibility of obtaining a strong phase transition in a Two-Higgs-Doublet Model of type II with a minimal amount of $CP$ violation. By performing a Bayesian fit where we constrain the scalar sector with indirect and direct measurements, we find that current data disfavours a first-order phase transition in this model. This result is mainly driven by the interplay of three effects: Constraints from the LHC Higgs data on the magnitude of the quartic couplings, the requirement of a $H^\\pm$ heavier than around 490 GeV to avoid large contributions to $BR(b \\rightarrow s\\gamma)$ and the fact that a first-order phase transition requires relatively light scalar states in addition to the 125 GeV Higgs. For similar reasons we find that a "hidden-Higgs" scenario, in which the 125 GeV state is identified with the next-to-lightest scalar, is disfavoured by current data independent of any require...

  1. The electroweak theory

    Energy Technology Data Exchange (ETDEWEB)

    Chris Quigg

    2001-08-10

    After a short essay on the current state of particle physics, the author reviews the antecedents of the modern picture of the weak and electromagnetic interactions and then undertakes a brief survey of the SU(2){sub L} {circle_times} U(1){sub Y} electroweak theory. The authors reviews the features of electroweak phenomenology at tree level and beyond, presents an introduction to the Higgs boson and the 1-TeV scale, and examines arguments for enlarging the electroweak theory. The author concludes with a brief look at low-scale gravity.

  2. Quantum mechanics and the second law of thermodynamics: an insight gleaned from magnetic hysteresis in the first order phase transition of an isolated mesoscopic-size type I superconductor

    Science.gov (United States)

    Keefe, Peter D.

    2012-11-01

    J Bardeen proposed that the adiabatic phase transition of mesoscopic-size type I superconductors must be accompanied by magnetic hysteresis in the critical magnetic field of sufficient magnitude to satisfy the second law of thermodynamics, herein referred to as ‘Bardeen Hysteresis’. Bardeen Hysteresis remains speculative in that it has not been reported in the literature. This paper investigates Bardeen Hysteresis as a possible accompaniment to the adiabatic phase transition of isolated mesoscopic-size type I superconductors and its implications with respect to the second law of thermodynamics. A causal mechanism for Bardeen Hysteresis is discussed which contrasts with the long accepted causal mechanism of magnetic hysteresis, as first summarized by Pippard, herein referred to as ‘Pippard Hysteresis’. The paper offers guidance for an experimental verification and comments on how the existence of Bardeen Hysteresis has relation to a quantum mechanical basis for the second law of thermodynamics.

  3. The magnetic phase transition and the low-field Arrott plots of (GD{sub x}Dy{sub 1-x})Co{sub 2} compounds[75.20.En; 75.30.Kz; (GdxDy1-x)Co2 compounds; First-order transition; Second-order transition; Arrott plots

    Energy Technology Data Exchange (ETDEWEB)

    Wang Dunhui E-mail: wangdh@nju.edu.cn; Tang Shaolong; Huang Songling; Zhang Jianrong; Du Youwei

    2004-01-01

    A series of (Gd{sub x}Dy{sub 1-x})Co{sub 2} (0-0.55) compounds have been prepared by arc-melting method. In order to determine the phase transition order in these compounds, we have performed some magnetization measurements. Only from the plots of temperature dependence of magnetization and the low-field magnetization isotherms, it is difficult to judge the phase transition order. The low-field Arrott plot is proved to be a more reliable method to characterize the first-order transition and the second-order transition. No first-order transition is observed in (Gd{sub x}Dy{sub 1-x})Co{sub 2} compounds (x{ne}0). The result is discussed in the Inoue-Shimizu like model.

  4. Coulomb interaction and first-order superconductor-insulator transition.

    Science.gov (United States)

    Syzranov, S V; Aleiner, I L; Altshuler, B L; Efetov, K B

    2010-09-24

    The superconductor-insulator transition (SIT) in regular arrays of Josephson junctions is studied at low temperatures. We derived an imaginary time Ginzburg-Landau-type action properly describing the Coulomb interaction. The renormalization group analysis at zero temperature T=0 in the space dimensionality d=3 shows that the SIT is always of the first order. At finite T, a tricritical point separates the lines of the first- and second-order phase transitions. The same conclusion holds for d=2 if the mutual capacitance is larger than the distance between junctions.

  5. A unified explanation for dark matter and electroweak baryogenesis with direct detection and gravitational wave signatures

    Energy Technology Data Exchange (ETDEWEB)

    Chala, Mikael [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Nardini, Germano [Bern Univ. (Switzerland). Inst. for Theoretical Physics; Sobolev, Ivan [Russian Academy of Sciences, Moscow (Russian Federation). Inst. for Nuclear Research; Moscow State Univ. (Russian Federation). Dept. of Particle Physics and Cosmology

    2016-05-15

    A minimal extension of the Standard Model that provides both a dark matter candidate and a strong first-order electroweak phase transition (EWPT) consists of two additional Lorentz and gauge singlets. In this paper we work out a composite Higgs version of this scenario, based on the coset SO(7)/SO(6). We show that by embedding the elementary fermions in appropriate representations of SO(7), all dominant interactions are described by only three free effective parameters. Within the model dependencies of the embedding, the theory predicts one of the singlets to be stable and responsible for the observed dark matter abundance. At the same time, the second singlet introduces new CP-violation phases and triggers a strong first-order EWPT, making electroweak baryogenesis feasible. It turns out that this scenario does not conflict with current observations and it is promising for solving the dark matter and baryon asymmetry puzzles. The tight predictions of the model will be accessible at the forthcoming dark matter direct detection and gravitational wave experiments.

  6. A unified explanation for dark matter and electroweak baryogenesis with direct detection and gravitational wave signatures

    CERN Document Server

    Chala, Mikael; Sobolev, Ivan

    2016-01-01

    A minimal extension of the Standard Model that provides both a dark matter candidate and a strong first-order electroweak phase transition (EWPT) consists of two additional Lorentz and gauge singlets. In this paper we work out a composite Higgs version of this scenario, based on the coset $SO(7)/SO(6)$. We show that by embedding the elementary fermions in appropriate representations of $SO(7)$, all dominant interactions are described by only three free effective parameters. Within the model dependencies of the embedding, the theory predicts one of the singlets to be stable and responsible for the observed dark matter abundance. At the same time, the second singlet introduces new $CP$-violation phases and triggers a strong first-order EWPT, making electroweak baryogenesis feasible. It turns out that this scenario does not conflict with current observations and it is promising for solving the dark matter and baryon asymmetry puzzles. The tight predictions of the model will be accessible at the forthcoming dark ...

  7. Unified explanation for dark matter and electroweak baryogenesis with direct detection and gravitational wave signatures

    Science.gov (United States)

    Chala, Mikael; Nardini, Germano; Sobolev, Ivan

    2016-09-01

    A minimal extension of the Standard Model that provides both a dark matter candidate and a strong first-order electroweak phase transition (EWPT) consists of two additional Lorentz and gauge singlets. In this paper we work out a composite Higgs version of this scenario, based on the coset S O (7 )/S O (6 ). We show that by embedding the elementary fermions in appropriate representations of S O (7 ), all dominant interactions are described by only three free effective parameters. Within the model dependencies of the embedding, the theory predicts one of the singlets to be stable and responsible for the observed dark matter abundance. At the same time, the second singlet introduces new C P -violation phases and triggers a strong first-order EWPT, making electroweak baryogenesis feasible. It turns out that this scenario does not conflict with current observations and it is promising for solving the dark matter and baryon asymmetry puzzles. The tight predictions of the model will be accessible at the forthcoming dark matter direct detection and gravitational wave experiments.

  8. Subphase transitions in first-order aggregation processes

    Science.gov (United States)

    Koci, Tomas; Bachmann, Michael

    2017-03-01

    In this paper, we investigate the properties of aggregation transitions in the context of generic coarse-grained homopolymer systems. By means of parallel replica-exchange Monte Carlo methods, we perform extensive simulations of systems consisting of up to 20 individual oligomer chains with five monomers each. Using the tools of the versatile microcanonical inflection-point analysis, we show that the aggregation transition is a first-order process consisting of a sequence of subtransitions between intermediate structural phases. We unravel the properties of these intermediate phases by collecting and analyzing their individual contributions towards the density of states of the system. The central theme of this systematic study revolves around translational entropy and its role in the striking phenomena of missing intermediate phases. We conclude with a brief discussion of the scaling properties of the transition temperature and the latent heat.

  9. Dynamic finite-size scaling at first-order transitions

    Science.gov (United States)

    Pelissetto, Andrea; Vicari, Ettore

    2017-07-01

    We investigate the dynamic behavior of finite-size systems close to a first-order transition (FOT). We develop a dynamic finite-size scaling (DFSS) theory for the dynamic behavior in the coexistence region where different phases coexist. This is characterized by an exponentially large time scale related to the tunneling between the two phases. We show that, when considering time scales of the order of the tunneling time, the dynamic behavior can be described by a two-state coarse-grained dynamics. This allows us to obtain exact predictions for the dynamical scaling functions. To test the general DFSS theory at FOTs, we consider the two-dimensional Ising model in the low-temperature phase, where the external magnetic field drives a FOT, and the 20-state Potts model, which undergoes a thermal FOT. Numerical results for a purely relaxational dynamics fully confirm the general theory.

  10. First-Order-Like Transition for Dispersive Optical Bistability

    Institute of Scientific and Technical Information of China (English)

    HE Ying; ZHU Shi-Qun

    2003-01-01

    The first-order-like phase transition (FOLT) in the dispersive optical bistability is investigated when the fluctuation in the incident light field is considered as colored noise. A unified colored-noise approximation is applied to obtain the steady state distribution (SSD) when either the intensity or phase fluctuations of the incident field are included in the system. For intensity fluctuations only, the curve of SSD is changed from single extreme to two extremes, and then to three extremes. The colored nature of the noise can reduce the fluctuation in the system. However, for phase fluctuations only, the FOLT is mainly induced by the colored nature of the noise. The curve of SSD is changed from single extreme to three extremes directly. There is no FOLT existing for white noise.

  11. Reversible magnetocaloric effect in materials with first order phase transitions in cyclic magnetic fields: Fe48Rh52 and Sm0.6Sr0.4MnO3

    Science.gov (United States)

    Aliev, A. M.; Batdalov, A. B.; Khanov, L. N.; Kamantsev, A. P.; Koledov, V. V.; Mashirov, A. V.; Shavrov, V. G.; Grechishkin, R. M.; Kaul', A. R.; Sampath, V.

    2016-11-01

    The magnetocaloric effect (MCE) in an Fe48Rh52 alloy and Sm0.6Sr0.4MnO3 manganite was studied in cyclic magnetic fields. The adiabatic temperature change in the Fe48Rh52 alloy for a magnetic field change (ΔB) of 8 T and a frequency (f) of 0.13 Hz reaches the highest value of (ΔTad) of -20.2 K at 298 K. The magnitude of the MCE in Sm0.6Sr0.4MnO3 reaches ΔTad = 6.1 K at the same magnetic field change at 143 K. The temperature regions, where a strong MCE is exhibited in an alternating magnetic field, are bounded in both compounds. In the case of the Fe48Rh52 alloy, the temperature range for this phenomenon is bounded above by the ferromagnetic to antiferromagnetic transition temperature in the zero field condition during cooling. In the case of the Sm0.6Sr0.4MnO3 manganite, the temperature range for the MCE is bounded below by the ferromagnetic-paramagnetic transition temperature in zero field during heating. The presence of these phase boundaries is a consequence of the existence of areas of irreversible magnetic-field-induced phase transitions. It is found that the effect of long-term action of thousands of cycles of magnetization/demagnetization degrades the magnetocaloric properties of the Fe48Rh52 alloy. This can be explained by the gradual decrease in the size of the ferromagnetic domains and increasing role of the domain walls due to giant magnetostriction at the ferromagnetic to antiferromagnetic transition temperature. The initial magnetocaloric properties can be restored by heating of the material above their Curie temperature.

  12. Magnetic and magnetocaloric properties in La{sub 0.7}Ca{sub 0.3−x}Na{sub x}MnO{sub 3} exhibiting first-order and second-order magnetic phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Ho, T.A. [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Dang, N.T. [Institute of Research and Development, Duy Tan University, Da Nang (Viet Nam); Phan, The-Long [Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin 449-791 (Korea, Republic of); Yang, D.S. [Physics Division, School of Science Education, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Lee, B.W. [Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin 449-791 (Korea, Republic of); Yu, S.C., E-mail: scyu@chungbuk.ac.kr [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)

    2016-08-15

    Polycrystalline orthorhombic samples La{sub 0.7}Ca{sub 0.3−x}Na{sub x}MnO{sub 3} (x = 0–0.09) were prepared by solid-state reaction. The study of magnetic properties revealed that the ferromagnetic-paramagnetic (FM-PM) transition temperature (T{sub C}) increases from 255 to about 271 K with increasing Na-doping content (x) from 0 to 0.09, respectively. Around the T{sub C}, we have found the samples showing a large magnetocaloric (MC) effect with maximum values of magnetic entropy change (|ΔS{sub max}|) of 7–8 J kg{sup −1} K{sup −1} and relative cooling power RCP = 232–236 J/kg for the samples x = 0.03–0.09 in a magnetic-field interval ΔH = 40 kOe. Detailed analyses of isothermal magnetization data M(T, H) based on Banerjee's criteria indicated a first-to-second-order magnetic-phase transformation taking place at a threshold Na-doping concentration x{sub c} ≈ 0.06. This could also be observed clearly from the feature of entropy universal curves. An assessment of the magnetic-ordering exponent N = dLn|ΔS{sub m}|/dLnH demonstrates an existence of short-range magnetic order in the samples. We believe that the changes of the magnetic properties and MC effect in La{sub 0.7}Ca{sub 0.3−x}Na{sub x}MnO{sub 3} caused by Na doping are related to the changes in the structural parameters and Mn{sup 4+}/Mn{sup 3+} ratio, which are confirmed by the geometrical and electronic analyses based on X-ray diffraction and X-ray absorption fine structure. - Highlights: • Geometrical and electronic structures of La{sub 0.7}Ca{sub 0.3−x}Na{sub x}MnO{sub 3}. • Threshold of first-to-second-order phase transformation in La{sub 0.7}Ca{sub 0.3−x}Na{sub x}MnO{sub 3}. • Large magneto-caloric effect with |ΔS{sub max}| ≈ 7–8 J kg{sup −1} K{sup −1}, and RCP = 232–236 J/kg. • Universal curve of magnetic-entropy change.

  13. Finite energy electroweak dyon

    Energy Technology Data Exchange (ETDEWEB)

    Kimm, Kyoungtae [Seoul National University, Faculty of Liberal Education, Seoul (Korea, Republic of); Yoon, J.H. [Konkuk University, Department of Physics, College of Natural Sciences, Seoul (Korea, Republic of); Cho, Y.M. [Konkuk University, Administration Building 310-4, Seoul (Korea, Republic of); Seoul National University, School of Physics and Astronomy, Seoul (Korea, Republic of)

    2015-02-01

    The latest MoEDAL experiment at LHC to detect the electroweak monopole makes the theoretical prediction of the monopole mass an urgent issue. We discuss three different ways to estimate the mass of the electroweak monopole. We first present the dimensional and scaling arguments which indicate the monopole mass to be around 4 to 10 TeV. To justify this we construct finite energy analytic dyon solutions which could be viewed as the regularized Cho-Maison dyon, modifying the coupling strength at short distance. Our result demonstrates that a genuine electroweak monopole whose mass scale is much smaller than the grand unification scale can exist, which can actually be detected at the present LHC. (orig.)

  14. Fundamental composite electroweak dynamics

    DEFF Research Database (Denmark)

    Arbey, Alexandre; Cacciapaglia, Giacomo; Cai, Haiying

    2017-01-01

    Using the recent joint results from the ATLAS and CMS collaborations on the Higgs boson, we determine the current status of composite electroweak dynamics models based on the expected scalar sector. Our analysis can be used as a minimal template for a wider class of models between the two limiting...... cases of composite Goldstone Higgs and Technicolor-like ones. This is possible due to the existence of a unified description, both at the effective and fundamental Lagrangian levels, of models of composite Higgs dynamics where the Higgs boson itself can emerge, depending on the way the electroweak...... space at the effective Lagrangian level. We show that a wide class of models of fundamental composite electroweak dynamics are still compatible with the present constraints. The results are relevant for the ongoing and future searches at the Large Hadron Collider....

  15. Precision Electroweak Measurements

    CERN Document Server

    Przysiezniak, H

    2000-01-01

    This talk describes some of the precision electroweak measurements from around the world, namely those related to the Z and W bosons, the top quark mass, sin2 theta_ W at NuTeV, and three other fundamental measurements: alpha-1 m2_ Z, (g-2)_mu at the E821 BNL experiment as well as the atomic parity violation (APV) measurement for the Cesium atom. These and other measurements are set in the context of the Standard Model (SM) and of the electroweak fit predictions. Future prospects for forthcoming experiments are briefly discussed.

  16. First-order phase transitions and giant magnetocaloric effect

    NARCIS (Netherlands)

    Nguyen, T.T.

    2010-01-01

    Modern society relies on cooling technology for food safety, comfort and medical applications. The solid-state cooling technology known as magnetic refrigeration is one of the most promising techniques to replace the current vapor-compression cooling technology. To date, the search for suitable mate

  17. First-order phase transitions and giant magnetocaloric effect

    NARCIS (Netherlands)

    Nguyen, T.T.

    2010-01-01

    Modern society relies on cooling technology for food safety, comfort and medical applications. The solid-state cooling technology known as magnetic refrigeration is one of the most promising techniques to replace the current vapor-compression cooling technology. To date, the search for suitable mate

  18. First-order phase transitions and giant magnetocaloric effect

    NARCIS (Netherlands)

    Nguyen, T.T.

    2010-01-01

    Modern society relies on cooling technology for food safety, comfort and medical applications. The solid-state cooling technology known as magnetic refrigeration is one of the most promising techniques to replace the current vapor-compression cooling technology. To date, the search for suitable

  19. Electroweak Physics at LHC

    CERN Document Server

    Erler, J

    2006-01-01

    The prospects for electroweak physics at the LHC are reviewed focusing mainly on precision studies. This includes projections for measurements of the effective Z pole weak mixing angle, of top quark, W boson, and Higgs scalar properties, and new physics searches.

  20. Electroweak physics at LHCb

    CERN Document Server

    Bifani, Simone

    2014-01-01

    Measurements of electroweak boson production provide an important test of the Standard Model at the LHC energies and allow the partonic content of the proton to be constrained. $W$ and $Z$ bosons are reconstructed in several leptonic final states using data samples corresponding to an integrated luminosity of up to about 1 $fb^{-1}$. Inclusive and associated production cross-sections are reported.

  1. EXACT AND ADIABATIC INVARIANTS OF FIRST-ORDER LAGRANGE SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    陈向炜; 尚玫; 梅凤翔

    2001-01-01

    A system of first-order differential equations is expressed in the form of first-order Lagrange equations. Based on the theory of symmetries and conserved quantities of first-order Lagrange systems, the perturbation to the symmetries and adiabatic invariants of first-order Lagrange systems are discussed. Firstly, the concept of higher-order adiabatic invariants of the first-order Lagrange system is proposed. Then, conditions for the existence of the exact and adiabatic invariants are proved, and their forms are given. Finally, an example is presented to illustrate these results.

  2. Effective field theory, electric dipole moments and electroweak baryogenesis

    Science.gov (United States)

    Balazs, Csaba; White, Graham; Yue, Jason

    2017-03-01

    Negative searches for permanent electric dipole moments (EDMs) heavily constrain models of baryogenesis utilising various higher dimensional charge and parity violating (CPV) operators. Using effective field theory, we create a model independent connection between these EDM constraints and the baryon asymmetry of the universe (BAU) produced during a strongly first order electroweak phase transition. The thermal aspects of the high scale physics driving the phase transition are paramaterised by the usual kink solution for the bubble wall profile. We find that operators involving derivatives of the Higgs field yield CPV contributions to the BAU containing derivatives of the Higgs vacuum expectation value (vev), while non-derivative operators lack such contributions. Consequently, derivative operators cannot be eliminated in terms of non-derivative operators (via the equations of motion) if one is agnostic to the new physics that leads to the phase transition. Thus, we re-classify the independent dimension six operators, restricting ourselves to third generation quarks, gauge bosons and the Higgs. Finally, we calculate the BAU (as a function of the bubble wall width and the cutoff) for a derivative and a non-derivative operator, and relate it to the EDM constraints.

  3. The Sphaleron in a Magnetic Field and Electroweak Baryogenesis

    CERN Document Server

    Comelli, D; Pietroni, M; Riotto, Antonio

    1999-01-01

    The presence of a primordial magnetic field in the early universe affects the dynamic of the electroweak phase transition enhancing its strength. This effect may enlarge the window for electroweak baryogenesis in the minimal supersymmetric extension of the standard model or even resurrect the electroweak baryogenesis scenario in the standard model. We compute the sphaleron energy in the background of the magnetic field and show that, due to the sphaleron dipole moment, the barrier between topologically inequivalent vacua is lowered. Therefore, the preservation of the baryon asymmetry calls for a much stronger phase transition than required in the absence of a magnetic field. We show that this effect overwhelms the gain in the phase transition strength, and conclude that magnetic fields do not help electroweak baryogenesis.

  4. Electroweak interactions at LEP

    CERN Document Server

    Swain, J D

    2000-01-01

    The electroweak interactions are based on an extension of the electromagnetic (Maxwell) interactions, realized in a rather odd way so that the symmetries of the theory are not immediately obvious. This "broken" theory has been the subject of intense investigation at LEP, and has passed all tests with flying colours. These lectures are meant to complement the many excellent presentations of the standard SU(2)/sub L/*U(1)/sub Y/ electroweak interactions in three main ways: first to clarify the physical meaning of symmetries in particle physics, second, to summarize the recent tests of the standard model using LEP data, and finally to look at possible roles of gravity in understanding mass. (10 refs).

  5. Electroweak penguin B decays

    CERN Document Server

    Nikodem, Thomas

    2016-01-01

    Flavour Changing Neutral Currents (FCNC) are sensitive probes for physics beyond the Standard Model (SM), so-called New Physics. An example of a FCNC is the $b \\to s$ quark transition described by the electroweak penguin Feynman diagram shown in Figure 1. In the SM such FCNC are only allowed with a loop structure (as e:g: shown in the figure) and not by tree level processes. In the loops heavy particles appear virtually and do not need to be on shell. Therefore also not yet discovered heavy particles with up to a mass $\\mathcal{O}$(TeV) could virtually contribute significantly to observables. Several recent measurements of electroweak penguin B decays exhibit interesting tensions with SM predictions, most prominently in the angular observable $P'_5$ 5 of the decay $B^0 \\to K^{*0} \\mu^+ \\mu^1$[1], which triggered a lot of discussion in the theory community [2]-[14].

  6. Field Method for Integrating the First Order Differential Equation

    Institute of Scientific and Technical Information of China (English)

    JIA Li-qun; ZHENG Shi-wang; ZHANG Yao-yu

    2007-01-01

    An important modern method in analytical mechanics for finding the integral, which is called the field-method, is used to research the solution of a differential equation of the first order. First, by introducing an intermediate variable, a more complicated differential equation of the first order can be expressed by two simple differential equations of the first order, then the field-method in analytical mechanics is introduced for solving the two differential equations of the first order. The conclusion shows that the field-method in analytical mechanics can be fully used to find the solutions of a differential equation of the first order, thus a new method for finding the solutions of the first order is provided.

  7. Nonequilibrium gap collapse near a first-order Mott transition

    Science.gov (United States)

    Sandri, Matteo; Fabrizio, Michele

    2015-03-01

    We study the nonequilibrium dynamics of a simple model for V2O3 that consists of a quarter-filled Hubbard model for two orbitals that are split by a weak crystal field. Peculiarities of this model are (1) a Mott insulator whose gap corresponds to transferring an electron from the occupied lower orbital to the empty upper one, rather than from the lower to the upper Hubbard subbands; (2) a Mott transition generically of first order even at zero temperature. We simulate by means of time-dependent Gutzwiller approximation the evolution within the insulating phase of an initial state endowed by a nonequilibrium population of electrons in the upper orbital and holes in the lower one. We find that the excess population may lead, above a threshold, to a gap collapse and drive the insulator into the metastable metallic phase within the coexistence region around the Mott transition. This result foresees a nonthermal pathway to revert a Mott insulator into a metal. Even though this physical scenario is uncovered in a very specific toy model, we argue it might apply to other Mott insulating materials that share similar features.

  8. Electroweak Baryogenesis and Colored Scalars

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Timothy; /SLAC /Michigan U., MCTP; Pierce, Aaron; /Michigan U., MCTP

    2012-02-15

    We consider the 2-loop finite temperature effective potential for a Standard Model-like Higgs boson, allowing Higgs boson couplings to additional scalars. If the scalars transform under color, they contribute 2-loop diagrams to the effective potential that include gluons. These 2-loop effects are perhaps stronger than previously appreciated. For a Higgs boson mass of 115 GeV, they can increase the strength of the phase transition by as much as a factor of 3.5. It is this effect that is responsible for the survival of the tenuous electroweak baryogenesis window of the Minimal Supersymmetric Standard Model. We further illuminate the importance of these 2-loop diagrams by contrasting models with colored scalars to models with singlet scalars. We conclude that baryogenesis favors models with light colored scalars. This motivates searches for pair-produced di-jet resonances or jet(s) + = E{sub T}.

  9. A First-Order One-Pass CPS Transformation

    DEFF Research Database (Denmark)

    Danvy, Olivier; Nielsen, Lasse Reichstein

    2001-01-01

    We present a new transformation of λ-terms into continuation-passing style (CPS). This transformation operates in one pass and is both compositional and first-order. Previous CPS transformations only enjoyed two out of the three properties of being first-order, one-pass, and compositional...

  10. A First-Order One-Pass CPS Transformation

    DEFF Research Database (Denmark)

    Danvy, Olivier; Nielsen, Lasse Reichstein

    2003-01-01

    We present a new transformation of λ-terms into continuation-passing style (CPS). This transformation operates in one pass and is both compositional and first-order. Previous CPS transformations only enjoyed two out of the three properties of being first-order, one-pass, and compositional...

  11. Electroweak Domain Wall by Hawking Radiation Baryogenesis and Dark Matter from Several Hundred kg Black Holes

    CERN Document Server

    Nagatani, Y

    2001-01-01

    We show that a spherical electroweak domain wall is formed around a small black hole and this is a general property of the Hawking radiation in the vacuum of the Standard Model. The wall appears not only for the first order phase transition in the electroweak theory but also for the second order one because the black hole heats up its neighborhood locally by the Hawking radiation in any case. We propose a model for unifying the origin of the baryon number and the cold dark matter in our universe by using properties of the primordial black hole with a mass of several hundred kilograms. The interaction between our wall and the Hawking-radiated-particles can create a baryon number which is proportional to the mass of the black hole as well as the CP broken phase in the extension of the Standard Model. Our model can explain both the baryon-entropy ratio B/S \\sim 10^{-10} and the energy density of the dark matter, provided that the following three conditions are satisfied: (i) the primordial black holes dominate i...

  12. CP violation during the electroweak sphaleron transitions

    CERN Document Server

    Shuryak, Edward

    2016-01-01

    We suggest a specific semiclassical background field, the so called pure gauge sphaleron explosion, to evaluate the magnitude of the CP violation stemming from the standard phase of the CKM matrix. We use it to evaluate the matrix elements of some next-to-leading order effective CP-violating operators suggested in the literature. We also derive the scale dependence of the corresponding coefficients. Finally, we discuss the expected magnitude of the CP violation in the cold electroweak scenario.

  13. Electroweak Baryogenesis and the Standard Model

    OpenAIRE

    Huet, Patrick

    1994-01-01

    Electroweak baryogenesis is addressed within the context of the standard model of particle physics. Although the minimal standard model has the means of fulfilling the three Sakharov's conditions, it falls short to explaining the making of the baryon asymmetry of the universe. In particular, it is demonstrated that the phase of the CKM mixing matrix is an insufficient source of {\\it CP} violation. The shortcomings of the standard model could be bypassed by enlarging the symmetry breaking sect...

  14. Birefringent Electroweak Textures

    CERN Document Server

    Thatcher, M J; Thatcher, Marcus J.; Morgan, Michael J.

    1999-01-01

    The behaviour of electromagnetic waves propagating through an electroweak homilia string network is examined. This string network is topologically stable as a cosmic texture, and is characterized by the spatial variation of the isospin rotation of the Higgs field. As a consequence the photon field couples to the intermediate vector bosons, producing a finite range electromagnetic field. It is found that the propagation speed of the photon depends on its polarization vector, whence an homilia string network acts as a birefringent medium. We estimate the birefringent scale for this texture and show that it depends on the frequency of the electromagnetic wave and the length scale of the homilia string network.

  15. Introduction to Electroweak Symmetry Breaking

    CERN Document Server

    Dawson, S

    2009-01-01

    In these lectures, I review the status of the electroweak sector of the Standard Model, with an emphasis on the importance of radiative corrections and searches for the Standard Model Higgs boson. A discussion of the special role of the TeV energy scale in electroweak physics is included.

  16. The computation of first order moments on junction trees

    CERN Document Server

    Djuric, Milos B; Stankovic, Miomir S

    2012-01-01

    We review some existing methods for the computation of first order moments on junction trees using Shafer-Shenoy algorithm. First, we consider the problem of first order moments computation as vertices problem in junction trees. In this way, the problem is solved using the memory space of an order of the junction tree edge-set cardinality. After that, we consider two algorithms, Lauritzen-Nilsson algorithm, and Mau\\'a et al. algorithm, which computes the first order moments as the normalization problem in junction tree, using the memory space of an order of the junction tree leaf-set cardinality.

  17. Electroweak baryogenesis in extensions of the standard model

    Energy Technology Data Exchange (ETDEWEB)

    Fromme, L.

    2006-07-07

    We investigate the generation of the baryon asymmetry in two extensions of the Standard Model; these are the {phi}{sup 6} and the two-Higgs-doublet model. Analyzing the thermal potential in the presence of CP violation, we find a strong first order phase transition for a wide range of parameters in both models. We compute the relevant bubble wall properties which then enter the transport equations. In non-supersymmetric models electroweak baryogenesis is dominated by top transport, which we treat in the WKB approximation. We calculate the CP-violating source terms starting from the Dirac equation. We show how to resolve discrepancies between this treatment and the computation in the Schwinger-Keldysh formalism. Furthermore, we keep inelastic scatterings of quarks and W bosons at a finite rate, which considerably affects the amount of the generated baryon asymmetry depending on the bubble wall velocity. In addition, we improve the transport equations by novel source terms which are generated by CP-conserving perturbations in the plasma. It turns out that their effect is relatively small. Both models under consideration predict a baryon to entropy ratio close to the observed value for a large part of the parameter space without being in conflict with constraints on electric dipole moments. (orig.)

  18. Innovative first order elimination kinetics working model for easy learning

    Directory of Open Access Journals (Sweden)

    Navin Budania

    2016-06-01

    Conclusions: First order elimination kinetics is easily understood with the help of above working model. More and more working models could be developed for teaching difficult topics. [Int J Basic Clin Pharmacol 2016; 5(3.000: 862-864

  19. Quantifier hierarchies over the first-Order definable tree languages

    Institute of Scientific and Technical Information of China (English)

    沈云付

    1996-01-01

    Using Boolean operations and concatenation product w.r.t special trees,quantifier hierarchies are given by way of alternate existential and universal quantifiers for the first-order definable tree languages.

  20. First-order partial differential equations in classical dynamics

    Science.gov (United States)

    Smith, B. R.

    2009-12-01

    Carathèodory's classic work on the calculus of variations explores in depth the connection between ordinary differential equations and first-order partial differential equations. The n second-order ordinary differential equations of a classical dynamical system reduce to a single first-order differential equation in 2n independent variables. The general solution of first-order partial differential equations touches on many concepts central to graduate-level courses in analytical dynamics including the Hamiltonian, Lagrange and Poisson brackets, and the Hamilton-Jacobi equation. For all but the simplest dynamical systems the solution requires one or more of these techniques. Three elementary dynamical problems (uniform acceleration, harmonic motion, and cyclotron motion) can be solved directly from the appropriate first-order partial differential equation without the use of advanced methods. The process offers an unusual perspective on classical dynamics, which is readily accessible to intermediate students who are not yet fully conversant with advanced approaches.

  1. Modelling electroweak physics for the forward region

    CERN Document Server

    Sirendi, Marek

    2016-01-01

    This note presents a study of matching and merging schemes and weak showering at the LHC as applied to the production of electroweak bosons in association with jets. These advanced theoretical tools are seen to provide a good description of event shapes in the central region when compared to measurements performed by the ATLAS and CMS collaborations at a centre-of-mass energy of 7 TeV. Matching and merging schemes also provide a superior description of forward $Z+$jets production. The study constitutes a test of matching and merging schemes in a novel region of phase space and can be considered as a validation of the universality of these techniques. Finally, it was determined that current measurements of electroweak physics at LHCb do not yet fully probe the effect of weak showers.

  2. Radiative neutrino mass, dark matter and electroweak baryogenesis from the supersymmetric gauge theory with confinement

    Energy Technology Data Exchange (ETDEWEB)

    Kanemura, Shinya; Machida, Naoki [Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Shindou, Tetsuo [Division of Liberal-Arts, Kogakuin University, 1-24-2 Nishi-Shinjuku, Tokyo 163-8677 (Japan)

    2014-11-10

    We propose a simple model to explain neutrino mass, dark matter and baryogenesis based on the extended Higgs sector which appears in the low-energy effective theory of a supersymmetric gauge theory with confinement. We here consider the SU(2){sub H} gauge symmetry with three flavours of fundamental representations which are charged under the standard SU(3){sub C}×SU(2){sub L}×U(1){sub Y} symmetry and a new discrete Z{sub 2} symmetry. We also introduce a Z{sub 2}-odd right-handed neutrino superfield in addition to the standard model matter superfields. The low-energy effective theory below the confinement scale contains the Higgs sector with fifteen composite superfields, some of which are Z{sub 2}-odd. When the confinement scale is of the order of ten TeV, electroweak phase transition can be sufficiently of first order, which is required for successful electroweak baryogenesis. The lightest Z{sub 2}-odd particle can be a new candidate for dark matter, in addition to the lightest R-parity odd particle. Neutrino masses and mixings can be explained by the quantum effects of Z{sub 2}-odd fields via the one-loop and three-loop diagrams. We find a benchmark scenario of the model, where all the constraints from the current neutrino, dark matter, lepton flavour violation and LHC data are satisfied. Predictions of the model are shortly discussed.

  3. Radiative neutrino mass, dark matter and electroweak baryogenesis from the supersymmetric gauge theory with confinement

    CERN Document Server

    Kanemura, Shinya; Shindou, Tetsuo

    2014-01-01

    We propose a simple model to explain neutrino mass, dark matter and baryogenesis based on the extended Higgs sector which appears in the low-energy effective theory of a supersymmetric gauge theory with confinement. We here consider the SU(2)$_H$ gauge symmetry with three flavours of fundamental representations which are charged under the standard SU(3)$_C\\times$ SU(2)$_L\\times$U(1)$_Y$ symmetry and a new discrete $Z_2$ symmetry. We also introduce $Z_2$-odd right-handed neutrino superfields in addition to the standard model matter superfields. The low-energy effective theory below the confinement scale contains the Higgs sector with fifteen composite superfields, some of which are $Z_2$-odd. When the confinement scale is of the order of ten TeV, electroweak phase transition can be sufficiently of first order, which is required for successful electroweak baryogenesis. The lightest $Z_2$-odd particle can be a new candidate for dark matter, in addition to the lightest $R$-parity odd particle. Neutrino masses and...

  4. Introduction to Electroweak Symmetry Breaking

    Energy Technology Data Exchange (ETDEWEB)

    Dawson,S.

    2008-10-02

    The Standard Model (SM) is the backbone of elementary particle physics-not only does it provide a consistent framework for studying the interactions of quark and leptons, but it also gives predictions which have been extensively tested experimentally. In these notes, I review the electroweak sector of the Standard Model, discuss the calculation of electroweak radiative corrections to observables, and summarize the status of SM Higgs boson searches. Despite the impressive experimental successes, however, the electroweak theory is not completely satisfactory and the mechanism of electroweak symmetry breaking is untested. I will discuss the logic behind the oft-repeated statement: 'There must be new physics at the TeV scale'. These lectures reflect my strongly held belief that upcoming results from the LHC will fundamentally change our understanding of electroweak symmetry breaking. In these lectures, I review the status of the electroweak sector of the Standard Model, with an emphasis on the importance of radiative corrections and searches for the Standard Model Higgs boson. A discussion of the special role of the TeV energy scale in electroweak physics is included.

  5. Superconducting Electroweak Strings

    CERN Document Server

    Volkov, M S

    2007-01-01

    Classical solutions describing strings endowed with an electric charge and carrying a constant electromagnetic current are constructed within the bosonic sector of the Electroweak Theory. For any given ratio of the Higgs boson mass to W boson mass and for any Weinberg's angle, these strings comprise a family that can be parameterized by values of the current through their cross section, $I_3$, by their electric charge per unit string length, $I_0$, and by two integers. These parameters determine the electromagnetic and Z fluxes, as well as the angular momentum and momentum densities of the string. For $I_0\\to 0$ and $I_3\\to 0$ the solutions reduce to Z strings, or, for solutions with $I_0=\\pm I_3$, to the W-dressed Z strings whose existence was discussed some time ago.

  6. First-order Nilpotent Minimum Logics: first steps

    CERN Document Server

    Bianchi, Matteo

    2011-01-01

    First-order Nilpotent Minimum Logic was introduced in [EG01]; in [Gis03] it is showed that every finite NM-chain with negation fixpoint is complete w.r.t. the logic NM. In this paper we will show that this last result, in the first-order case, does not hold. We will study the sets of first-order tautologies of some subalgebras of [0,1]_NM: in particular finite NM-chains and other four infinite NM-chains (with and without negation fixpoint). Moreover we will find a connection between the validity, in an NM-chain, of certain first-order formulas and its order type. Finally, we will analyze axiomatization, undecidability and the monadic fragments. We will conclude with some remarks, future directions of research and open problems. This paper has been inspired by the work done, for first-order G\\"odel logic, in [BPZ07] and [BCF07]: when possible, we will point out the analogies and the differences with the G\\"odel's case.

  7. Electroweak scale neutrinos and Higgses

    CERN Document Server

    Aranda, Alfredo

    2009-01-01

    We present two different models with electroweak scale right-handed neutrinos. One of the models is created under the constraint that any addition to the Standard Model must not introduce new higher scales. The model contains right-handed neutrinos with electroweak scale masses and a lepton number violating singlet scalar field. The scalar phenomenology is also presented. The second model is a triplet Higgs model where again the right-handed neutrinos have electroweak scale masses. In this case the model has a rich scalar phenomenology and in particular we present the analysis involving the doubly charged Higgs.

  8. Formalization of the Resolution Calculus for First-Order Logic

    DEFF Research Database (Denmark)

    Schlichtkrull, Anders

    2016-01-01

    A formalization in Isabelle/HOL of the resolution calculus for first-order logic is presented. Its soundness and completeness are formally proven using the substitution lemma, semantic trees, Herbrand’s theorem, and the lifting lemma. In contrast to previous formalizations of resolution, it consi......A formalization in Isabelle/HOL of the resolution calculus for first-order logic is presented. Its soundness and completeness are formally proven using the substitution lemma, semantic trees, Herbrand’s theorem, and the lifting lemma. In contrast to previous formalizations of resolution...

  9. Equivalent linearization finds nonzero frequency corrections beyond first order

    CERN Document Server

    Chattopadhyay, Rohitashwa

    2016-01-01

    We show that the equivalent linearization technique, when used properly, enables us to calculate frequency corrections of weakly nonlinear oscillators beyond the first order in nonliearity. We illustrate the method by applying it to the cubic anharmonic oscillator and the Van der Pol oscillator that are respectively paradigmatic systems for modeling center-type oscillatory states and limit cycle type oscillatory states. The choice of these systems is also prompted by the fact that first order frequency corrections vanish for both these oscillators, thereby rendering the calculation of the higher order corrections rather important. The method presented herein is very general in nature and, hence, in principle applicable to any arbitrary periodic oscillator.

  10. An Analysis of the First Order Form of Gauge Theories

    CERN Document Server

    Kiriushcheva, N; McKeon, D G C

    2011-01-01

    The first order form of a Maxwell theory and U(1) gauge theory in which a gauge invariant mass term appears is analyzed using the Dirac procedure. The form of the gauge transformation which leaves the action invariant is derived from the constraints present. A non-Abelian generalization is similarly analyzed. This first order three dimensional massive gauge theory is rewritten in terms of two interacting vector fields. The constraint structure when using light-cone coordinates is considered. The relationship between first and second order forms of the two-dimensional Einstein-Hilbert action is explored where a Lagrange multiplier is used to ensure their equivalence.

  11. Electroweak physics at the LHC

    CERN Document Server

    Mozer, Matthias U

    2016-01-01

    The book discusses the recent experimental results obtained at the LHC that involve electroweak bosons. The results are placed into an appropriate theoretical and historical context. The work pays special attention to the rising subject of hadronically decaying bosons with high boosts, documenting the state-of-the-art identification techniques and highlighting example results their application. The document is not limited to electroweak physics in the strict sense, but also discusses the use of electroweak vector-bosons as tool in the study of other subjects in particle physics, such as determinations of the proton structure or the search for new exotic particles. The book is particularly well suited for graduate students, starting their thesis work on topics that involve electroweak bosons, as the book provides a comprehensive description of phenomena observable at current accelerators as well as a summary of the most relevant experimental techniques.

  12. Quantum transport and electroweak baryogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Konstandin, Thomas

    2013-02-15

    We review the mechanism of electroweak baryogenesis. The main focus of the review lies on the development of quantum transport equations from first principles in the Kadanoff-Baym framework. We emphasize the importance of the semi-classical force that leads to reliable predictions in most cases. Besides, we discuss the status of electroweak baryogenesis in the light of recent electric dipole moment probes and collider experiments in a variety of models.

  13. Quantum Transport and Electroweak Baryogenesis

    CERN Document Server

    Konstandin, Thomas

    2013-01-01

    We review the mechanism of electroweak baryogenesis. The main focus of the review lies on the development of quantum transport equations from first principles in the Kadanoff-Baym framework. We emphasize the importance of the semi-classical force that leads to reliable predictions in most cases. Besides, we discuss the status of electroweak baryogenesis in the light of recent electric dipole moment probes and collider experiments in a variety of models.

  14. Electroweak results from the tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Wood, D. [Fermi National Accelerator Laboratory, Batavia, IL (United States)

    1997-01-01

    Electroweak results are presented from the CDF and DO experiments based on data collected in recent runs of the Fermilab Tevatron Collider. The measurements include the mass and width of the W boson, the production cross sections of the W and Z bosons, and the W charge asymmetry. Additional results come from studies of events with pairs of electroweak gauge bosons and include limits on anomalous couplings.

  15. Multidimensional first-order dominance comparisons of population wellbeing

    DEFF Research Database (Denmark)

    Arndt, Thomas Channing; Siersbæk, Nikolaj; Østerdal, Lars Peter Raahave

    In this paper, we convey the concept of first-order dominance (FOD) with particular focus on applications to multidimensional population welfare comparisons. We give an account of the fundamental equivalent definitions of FOD, illustrated with simple numerical examples. An implementable method fo...

  16. The Resolution Calculus for First-Order Logic

    DEFF Research Database (Denmark)

    Schlichtkrull, Anders

    2016-01-01

    This theory is a formalization of the resolution calculus for first-order logic. It is proven sound and complete. The soundness proof uses the substitution lemma, which shows a correspondence between substitutions and updates to an environment. The completeness proof uses semantic trees, i.e. trees...

  17. Oscillation criteria for first-order forced nonlinear difference equations

    OpenAIRE

    Grace Said R; Agarwal Ravi P.; Smith Tim

    2006-01-01

    Some new criteria for the oscillation of first-order forced nonlinear difference equations of the form Δx(n)+q1(n)xμ(n+1) = q2(n)xλ(n+1)+e(n), where λ, μ are the ratios of positive odd integers 0 <μ < 1 and λ > 1, are established.

  18. Probabilistic peak detection for first-order chromatographic data

    NARCIS (Netherlands)

    Lopatka, M.; Vivó-Truyols, G.; Sjerps, M.J.

    2014-01-01

    We present a novel algorithm for probabilistic peak detection in first-order chromatographic data. Unlike conventional methods that deliver a binary answer pertaining to the expected presence or absence of a chromatographic peak, our method calculates the probability of a point being affected by suc

  19. A First-Order One-Pass CPS Transformation

    DEFF Research Database (Denmark)

    Danvy, Olivier; Nielsen, Lasse Reichstein

    2002-01-01

    We present a new transformation of call-by-value lambdaterms into continuation-passing style (CPS). This transformation operates in one pass and is both compositional and first-order. Because it operates in one pass, it directly yields compact CPS programs that are comparable to what one would...

  20. Code Generation for a Simple First-Order Prover

    DEFF Research Database (Denmark)

    Villadsen, Jørgen; Schlichtkrull, Anders; Halkjær From, Andreas

    2016-01-01

    We present Standard ML code generation in Isabelle/HOL of a sound and complete prover for first-order logic, taking formalizations by Tom Ridge and others as the starting point. We also define a set of so-called unfolding rules and show how to use these as a simple prover, with the aim of using...

  1. First Order Actions for New Massive Dual Gravities

    CERN Document Server

    Bracho, Alexangel

    2013-01-01

    We present a first order formulation for the fourth order action of the new massive dual gravity in four dimensions. This proposal is easily generalized to arbitrary dimension. Also, we obtain the dual actions for massless and massive Curtright fields in D dimensions.

  2. Alternate Gauge Electroweak Model

    CERN Document Server

    Dalton, Bill

    2010-01-01

    We describe an alternate gauge electroweak model that permits neutrinos with mass, and at the same time explains why right-handed neutrinos do not appear in weak interactions. This is a local gauge theory involving a space [V ] of three scalar functions. The standard Lagrangian density for the Yang-Mills field part and Higgs doublet remain invariant. A ma jor change is made in the transformation and corresponding Lagrangian density parts involving the right-handed leptons. A picture involving two types of right-handed leptons emerges. A dichotomy of matter on the [V ] space corresponds to coupled and uncoupled right-handed Leptons. Here, we describe a covariant dipole-mode solution in which the neutral bosons A{\\mu} and Z{\\mu} produce precessions on [V ]. The W {\\pm} {\\mu} bosons provide nutations on [V ], and consequently, provide transitions between the coupled and uncoupled regions. To elucidate the [V ] space matter dichotomy, and to generate the boson masses, we also provide an alternate potential Lagran...

  3. Interrupted Magnetic First Order Transitions and Kinetic Arrest probed with In-field Neutron Diffraction

    Science.gov (United States)

    Siruguri, V.; Kaushik, S. D.; Rayaprol, S.; Babu, P. D.; Chaddah, P.; Sampathkumaran, E. V.; Hoser, A.; Ritter, C.

    2016-09-01

    In-field neutron diffraction studies were carried out on two compounds that exhibit magnetic first order phase transitions (FOPT). It is shown that the FOPT can be interrupted by an external magnetic field, resulting in a coexistence of kinetically arrested metastable states and equilibrium phases. Use of a novel protocol CHUF (Cooling and Heating under Unequal Fields) helps to determine the coexisting phase fractions and also to observe the devitrification of the kinetically arrested phase into the equilibrium phase, in a manner similar to that found in structural glassy systems.

  4. Strong and Electroweak Matter 2004

    Science.gov (United States)

    Eskola, Kari J.; Kainulainen, Kimmo; Kajantie, Keijo; Rummukainen, Kari

    RHIC experimental summary: the message from pp, d+Au and Au+Au collisions / M. Calderón de la Barca Sánchez -- Hydrodynamic aspects of relativistic heavy ion collisions at RHIC / P. F. Kolb -- Photon emission in a hot QCD plasma / P. Aurenche -- In search of the saturation scale: intrinsic features of the CGC / H. Weigert -- From leading hadron suppression to jet quenching at RHIC and LHC / U. A. Wiedemann -- Lattice simulations with chemical potential / C. Schmidt -- Mesonic correlators in hot QCD / M. Laine -- Thermalization and plasma instabilities / P. Arnold -- Transport coefficients in hot QCD / G. D. Moore -- Classical fields and heavy ion collisions / T. Lappi -- Progress in nonequilibrium quantum field theory II / J. Berges and J. Serreau -- A general effective theory for dense quark matter / P. T. Reuter, Q. Wang and D. H. Rischke -- Thermal leptogenesis / M. Plümacher -- Cold electroweak Baryogenesis / J. Smit -- Proton-nucleus collisions in the color glass condensate framework / J.-P. Blaizot, F. Gelis and R. Venugopalan -- From classical to quantum saturation in the nuclear wavefunction / D. N. Triantafyllopoulos -- Charge correlations in heavy ion collisions / A. Rajantie -- Whitening of the quark-gluon plasma / S. Mrówczyński -- Progress in anisotropic plasma physics / P. Romatschke and M. Strickland -- Deconfinement and chiral symmetry: competing orders / K. Tuominen -- Relation between the chiral and deconfinement phase transitions / Y. Hatta -- Renormalized Polyakov loops, matrix models and the Gross-Witten point / A. Dumitru and J. T. Lenaghan -- The nature of the soft excitation at the critical end point of QCD / A. Jakovác ... [et al.] -- Thermodynamics of the 1+1-dimensional nonlinear sigma model through next-to-leading order in 1/N / H. J. Warringa -- Light quark meson correlations at high temperature / E. Laemann ... [et al.] -- Charmonia at finite momenta in a deconfined plasma / S. Datta ... [et al.] -- QCD thermodynamics: lattice

  5. Robust stabilizing first-order controllers for a class of time delay systems.

    Science.gov (United States)

    Saadaoui, Karim; Testouri, Sana; Benrejeb, Mohamed

    2010-07-01

    In this paper, stabilizing regions of a first-order controller for an all poles system with time delay are computed via parametric methods. First, the admissible ranges of one of the controller's parameters are obtained. Then, for a fixed value of this parameter, stabilizing regions in the remaining two parameters are determined using the D-decomposition method. Phase and gain margin specifications are then included in the design. Finally, robust stabilizing first-order controllers are determined for uncertain plants with an interval type uncertainty in the coefficients. Examples are given to illustrate the effectiveness of the proposed method.

  6. Fast Computation of First-Order Feature-Bispectrum Corrections

    CERN Document Server

    Adshead, Peter

    2012-01-01

    Features in the inflaton potential that are traversed in much less than an e-fold of the expansion can produce observably large non-Gaussianity. In these models first order corrections to the curvature mode function evolution induce effects at second order in the slow roll parameters that are generically greater than ~ 10% and can reach order unity for order unity power spectrum features. From a complete first order expression in generalized slow-roll, we devise a computationally efficient method that is as simple to evaluate as the leading order one and implements consistency relations in a controlled fashion. This expression matches direct numerical computation for step potential models of the dominant bispectrum configurations to better than 1% when features are small and 10% when features are order unity.

  7. Equivalent linearization finds nonzero frequency corrections beyond first order

    Science.gov (United States)

    Chattopadhyay, Rohitashwa; Chakraborty, Sagar

    2017-06-01

    We show that the equivalent linearization technique, when used properly, enables us to calculate frequency corrections of weakly nonlinear oscillators beyond the first order in nonlinearity. We illustrate the method by applying it to the conservative anharmonic oscillators and the nonconservative van der Pol oscillator that are respectively paradigmatic systems for modeling center-type oscillatory states and limit cycle type oscillatory states. The choice of these systems is also prompted by the fact that first order frequency corrections may vanish for both these types of oscillators, thereby rendering the calculation of the higher order corrections rather important. The method presented herein is very general in nature and, hence, in principle applicable to any arbitrary periodic oscillator.

  8. First-order asymptotic corrections to the meanfield limit

    Energy Technology Data Exchange (ETDEWEB)

    Christandl, Matthias [Institute for Theoretical Physics, ETH Zuerich, Wolfgang-Pauli-Strasse 27, CH-8093 Zuerich (Switzerland); Matjeschk, Robert; Werner, Reinhard [Leibniz Universitaet Hannover (Germany); Trimborn, Friederike [Leibniz Universitaet Hannover (Germany); Bundesministerium fuer Bildung und Forschung (Germany)

    2014-07-01

    We derive a complete algebraic theory for treating permutation invariant problems beyond separability to first order in the asymptotics. Our work builds on a C{sup *}-algebraic theory for permutation invariant operators on n-particles, with an algebraic description of the limit n→∞ (the mean-field limit). We use the fluctuation ansatz, a version of a non-commutative central limit, and derive a continuous-variable algebra (the fluctuation algebra) that asymptotically describes the 1/n-corrections to this meanfield limit. Using the fluctuation algebra, we derive a method for estimating the ground-state energy of mean-field models up to first order, and for estimating the time-evolution of correlations between different particles. Moreover, we show that the mean-field ground-state problem is closely related to the finite de Finetti problem and therefore obtain a lower bound, complementing recent results in this direction.

  9. A First-Order One-Pass CPS Transformation

    DEFF Research Database (Denmark)

    Danvy, Olivier; Nielsen, Lasse Reichstein

    2002-01-01

    We present a new transformation of call-by-value lambdaterms into continuation-passing style (CPS). This transformation operates in one pass and is both compositional and first-order. Because it operates in one pass, it directly yields compact CPS programs that are comparable to what one would...... write by hand. Because it is compositional, it allows proofs by structural induction. Because it is first-order, reasoning about it does not require the use of a logical relation. This new CPS transformation connects two separate lines of research. It has already been used to state a new and simpler...... correctness proof of a direct-style transformation, and to develop a new and simpler CPS transformation of control-flow information....

  10. A First-Order One-Pass CPS Transformation

    DEFF Research Database (Denmark)

    Danvy, Olivier; Nielsen, Lasse Reichstein

    2001-01-01

    We present a new transformation of λ-terms into continuation-passing style (CPS). This transformation operates in one pass and is both compositional and first-order. Previous CPS transformations only enjoyed two out of the three properties of being first-order, one-pass, and compositional......, but the new transformation enjoys all three properties. It is proved correct directly by structural induction over source terms instead of indirectly with a colon translation, as in Plotkin's original proof. Similarly, it makes it possible to reason about CPS-transformed terms by structural induction over...... source terms, directly.The new CPS transformation connects separately published approaches to the CPS transformation. It has already been used to state a new and simpler correctness proof of a direct-style transformation, and to develop a new and simpler CPS transformation of control-flow information....

  11. A First-Order One-Pass CPS Transformation

    DEFF Research Database (Denmark)

    Danvy, Olivier; Nielsen, Lasse Reichstein

    2003-01-01

    We present a new transformation of λ-terms into continuation-passing style (CPS). This transformation operates in one pass and is both compositional and first-order. Previous CPS transformations only enjoyed two out of the three properties of being first-order, one-pass, and compositional......, but the new transformation enjoys all three properties. It is proved correct directly by structural induction over source terms instead of indirectly with a colon translation, as in Plotkin's original proof. Similarly, it makes it possible to reason about CPS-transformed terms by structural induction over...... source terms, directly.The new CPS transformation connects separately published approaches to the CPS transformation. It has already been used to state a new and simpler correctness proof of a direct-style transformation, and to develop a new and simpler CPS transformation of control-flow information....

  12. Brake subharmonic solutions of first order Hamiltonian systems

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper,we mainly use the Galerkin approximation method and the iteration inequalities of the L-Maslov type index theory to study the properties of brake subharmonic solutions for the first order non-autonomous Hamiltonian systems.We prove that when the positive integers j and k satisfy the certain conditions,there exists a jT-periodic nonconstant brake solution zj such that zj and zkj are distinct.

  13. TTVFaster: First order eccentricity transit timing variations (TTVs)

    Science.gov (United States)

    Agol, Eric; Deck, Katherine

    2016-04-01

    TTVFaster implements analytic formulae for transit time variations (TTVs) that are accurate to first order in the planet-star mass ratios and in the orbital eccentricities; the implementations are available in several languages, including IDL, Julia, Python and C. These formulae compare well with more computationally expensive N-body integrations in the low-eccentricity, low mass-ratio regime when applied to simulated and to actual multi-transiting Kepler planet systems.

  14. Multidimensional first-order dominance comparisons of population wellbeing

    DEFF Research Database (Denmark)

    Arndt, Thomas Channing; Siersbæk, Nikolaj; Østerdal, Lars Peter Raahave

    In this paper, we convey the concept of first-order dominance (FOD) with particular focus on applications to multidimensional population welfare comparisons. We give an account of the fundamental equivalent definitions of FOD, illustrated with simple numerical examples. An implementable method...... for detecting dominances is explained along with a bootstrapping procedure that yields additional information relative to what can be obtained from dominance comparisons alone. We discuss strengths and weaknesses of FOD, compared to other multidimensional population comparison concepts, and describe practical...

  15. Multidimensional First-Order Dominance Comparisons of Population Wellbeing

    DEFF Research Database (Denmark)

    Siersbæk, Nikolaj; Østerdal, Lars Peter; Arndt, Channing

    2017-01-01

    This chapter conveys the concept of first-order dominance (FOD) with particular focus on applications to multidimensional population welfare comparisons. It gives an account of the fundamental equivalent definitions of FOD both in the one-dimensional and multidimensional setting, illustrated...... with simple numerical examples. An implementable method for detecting dominances that relies on linear programming is explained along with a bootstrapping procedure that yields additional information relative to what can be obtained from dominance comparisons alone. The chapter discusses strengths...

  16. First order formalism for the holographic duals of defect CFTs

    Energy Technology Data Exchange (ETDEWEB)

    Korovin, Yegor [KdV Institute for Mathematics, Institute for Theoretical Physics, Science Park 904, 1090 GL Amsterdam (Netherlands); School of Mathematical Sciences and STAG Research Centre, University of Southampton,Southampton SO17 1BJ (United Kingdom)

    2014-04-24

    We develop a first order formalism for constructing gravitational duals of conformal defects in a bottom up approach. Similarly as for the flat domain walls a single function specifies the solution completely. Using this formalism we construct several novel families of analytic solutions dual to conformal interfaces and boundaries. As a sample application we study the boundary OPE and entanglement entropy for one of the found defects.

  17. First-order optimality condition of basis pursuit denoise problem

    Institute of Scientific and Technical Information of China (English)

    朱玮; 舒适; 成礼智

    2014-01-01

    A new first-order optimality condition for the basis pursuit denoise (BPDN) problem is derived. This condition provides a new approach to choose the penalty param-eters adaptively for a fixed point iteration algorithm. Meanwhile, the result is extended to matrix completion which is a new field on the heel of the compressed sensing. The numerical experiments of sparse vector recovery and low-rank matrix completion show validity of the theoretic results.

  18. Subharmonic solutions for first-order Hamiltonian systems

    Directory of Open Access Journals (Sweden)

    Mohsen Timoumi

    2013-09-01

    Full Text Available In this article, we study the existence of periodic and subharmonic solutions for a class of non-autonomous first-order Hamiltonian systems such that the nonlinearity has a growth at infinity faster than $|x|^{\\alpha}$, $0\\leq\\alpha < 1$. We also study the minimality of periods for such solutions. Our results are illustrated by specific examples. The proofs are based on the least action principle and a generalized saddle point theorem.

  19. First-order framework for flat brane with auxiliary fields

    CERN Document Server

    Bazeia, D; Menezes, R

    2014-01-01

    This work deals with braneworld models in the presence of auxiliary fields. We investigate the case where Einstein's equation is modified with the inclusion of extra, non-dynamical terms. We show that the model supports first-order differential equations that solve the equations of motion, but the standard braneworld scenario changes under the presence of the parameter that controls the non-dynamical or auxiliary fields that modifies Einstein's equation.

  20. Multilevel first-order system least squares for PDEs

    Energy Technology Data Exchange (ETDEWEB)

    McCormick, S.

    1994-12-31

    The purpose of this talk is to analyze the least-squares finite element method for second-order convection-diffusion equations written as a first-order system. In general, standard Galerkin finite element methods applied to non-self-adjoint elliptic equations with significant convection terms exhibit a variety of deficiencies, including oscillations or nonmonotonicity of the solution and poor approximation of its derivatives, A variety of stabilization techniques, such as up-winding, Petrov-Galerkin, and stream-line diffusion approximations, have been introduced to eliminate these and other drawbacks of standard Galerkin methods. Yet, although significant progress has been made, convection-diffusion problems remain among the more difficult problems to solve numerically. The first-order system least-squares approach promises to overcome these deficiencies. This talk develops ellipticity estimates and discretization error bounds for elliptic equations (with lower order terms) that are reformulated as a least-squares problem for an equivalent first-order system. The main results are the proofs of ellipticity and optimal convergence of multiplicative and additive solvers of the discrete systems.

  1. A first order system model of fracture healing

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-ping; ZHANG Xian-long; LI Zhu-guo; YU Xin-gang

    2005-01-01

    A first order system model is proposed for simulating the influence of stress stimulation on fracture strength during fracture healing. To validate the model, the diaphyses of bilateral tibiae in 70 New Zealand rabbits were osteotomized and fixed with rigid plates and stress-relaxation plates, respectively. Stress shielding rate and ultimate bending strength of the healing bone were measured at 2 to 48 weeks postoperatively. Ratios of stress stimulation and fracture strength of the healing bone to those of intact bone were taken as the system input and output. The assumed first order system model can approximate the experimental data on fracture strength from the input of stress stimulation over time, both for the rigid plate group and the stress-relaxation plate group, with different system parameters of time constant and gain. The fitting curve indicates that the effect of mechanical stimulus occurs mainly in late stages of healing. First order system can model the stress adaptation process of fracture healing. This approach presents a simple bio-mathematical model of the relationship between stress stimulation and fracture strength, and has the potential to optimize planning of functional exercises and conduct parametric studies.

  2. Electroweak symmetry breaking via QCD.

    Science.gov (United States)

    Kubo, Jisuke; Lim, Kher Sham; Lindner, Manfred

    2014-08-29

    We propose a new mechanism to generate the electroweak scale within the framework of QCD, which is extended to include conformally invariant scalar degrees of freedom belonging to a larger irreducible representation of SU(3)c. The electroweak symmetry breaking is triggered dynamically via the Higgs portal by the condensation of the colored scalar field around 1 TeV. The mass of the colored boson is restricted to be 350  GeV≲mS≲3  TeV, with the upper bound obtained from perturbative renormalization group evolution. This implies that the colored boson can be produced at the LHC. If the colored boson is electrically charged, the branching fraction of the Higgs boson decaying into two photons can slightly increase, and moreover, it can be produced at future linear colliders. Our idea of nonperturbative electroweak scale generation can serve as a new starting point for more realistic model building in solving the hierarchy problem.

  3. ON THE HYPERBOLIC OBSTACLE PROBLEM OF FIRST ORDER

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper presents new results for strong solutions and their coincidence sets of the obstacle problem for linear hyperbolic operators of first order. An inequality similar to the LewyStampacchia ones for elliptic and parabolic problems is shown. Under nondegeneracy conditions the stability of the coincidence set is shown with respect to the variation of the data and with respect to approximation by semilinear hyperbolic problems. These results are applied to the asymptotic stability of the evolution problem with respect to the stationary coercive problem with obstacle.

  4. A first-order thermal model for building design

    Energy Technology Data Exchange (ETDEWEB)

    Mathews, E.H. [Centre for Experimental and Numerical Thermoflow, Univ. of Pretoria (South Africa); Richards, P.G. [Centre for Experimental and Numerical Thermoflow, Univ. of Pretoria (South Africa); Lombard, C. [Centre for Experimental and Numerical Thermoflow, Univ. of Pretoria (South Africa)

    1994-12-31

    Simplified thermal models of buildings can successfully be applied in building design. This paper describes the derivation and validation of a first-order thermal model which has a clear physical interpretation, is based on uncomplicated calculation procedures and requires limited input information. Because extensive simplifications and assumptions are inherent in the development of the model, a comprehensive validation study is reported. The validity of the thermal model was proven with 70 validation studies in 32 buildings comprising a wide range of thermal characteristics. The accuracy of predictions compares well with other sophisticated programs. The proposed model is considered to be eminently suitable for incorporation in an efficient design tool. (orig.)

  5. First order tune shift calculations for transverse betatron dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Garavaglia, T.

    1991-09-01

    An effective Hamiltonian, with non-linear magnetic multipole terms and momentum dispersion contributions, is used to obtain the first order tune-shift results for transverse betatron motion for protons in the Superconducting Super Collider (SSC). This Hamiltonian is represented in terms of action angle variables, and analytical results are obtained using symbolic algebra methods. Mathematical derivations of the transverse multipole expansion and of the transverse betatron equations, using an invariant action and curvilinear coordinates, are given in the appendices. Numerical and graphical tune-space results are given that illustrate the dependence of tune-shifts on injection amplitude and momentum spread. 10 refs., 7 figs.

  6. First-order allpass filter using multi-input OTA

    Science.gov (United States)

    Iqbal, S. Z.; Psychalinos, C.; Parveen, N.

    2013-10-01

    A novel first-order allpass filter, operating in voltage-mode, is introduced in this article. Compared with the corresponding already proposed structures, attractive offered benefits are the capability for simultaneous offering a minimum number of active and passive components, and the absence of any realisability restriction. These have been achieved by employing a multiple-input operational transconductance amplifier as active element. The performance of the proposed circuits has been evaluated through simulation results, utilising the Analog Design Environment of Cadence software.

  7. A first-order Temporal Logic for Actions

    CERN Document Server

    Schwind, Camilla

    2007-01-01

    We present a multi-modal action logic with first-order modalities, which contain terms which can be unified with the terms inside the subsequent formulas and which can be quantified. This makes it possible to handle simultaneously time and states. We discuss applications of this language to action theory where it is possible to express many temporal aspects of actions, as for example, beginning, end, time points, delayed preconditions and results, duration and many others. We present tableaux rules for a decidable fragment of this logic.

  8. Temporal aggregation in first order cointegrated vector autoregressive

    DEFF Research Database (Denmark)

    la Cour, Lisbeth Funding; Milhøj, Anders

    2006-01-01

    We study aggregation - or sample frequencies - of time series, e.g. aggregation from weekly to monthly or quarterly time series. Aggregation usually gives shorter time series but spurious phenomena, in e.g. daily observations, can on the other hand be avoided. An important issue is the effect of ...... of aggregation on the adjustment coefficient in cointegrated systems. We study only first order vector autoregressive processes for n dimensional time series Xt, and we illustrate the theory by a two dimensional and a four dimensional model for prices of various grades of gasoline....

  9. Temporal aggregation in first order cointegrated vector autoregressive models

    DEFF Research Database (Denmark)

    La Cour, Lisbeth Funding; Milhøj, Anders

    We study aggregation - or sample frequencies - of time series, e.g. aggregation from weekly to monthly or quarterly time series. Aggregation usually gives shorter time series but spurious phenomena, in e.g. daily observations, can on the other hand be avoided. An important issue is the effect of ...... of aggregation on the adjustment coefficient in cointegrated systems. We study only first order vector autoregressive processes for n dimensional time series Xt, and we illustrate the theory by a two dimensional and a four dimensional model for prices of various grades of gasoline...

  10. Electroweak baryogenesis from a dark sector arXiv

    CERN Document Server

    Cline, James M.; Tucker-Smith, David

    Adding an extra singlet scalar $S$ to the Higgs sector can provide a barrier at tree level between a false vacuum with restored electroweak symmetry and the true one. This has been demonstrated to readily give a strong phase transition as required for electroweak baryogenesis. We show that with the addition of a fermionic dark matter particle $\\chi$ coupling to $S$, a simple UV-complete model can realize successful electroweak baryogenesis. The dark matter gets a CP asymmetry that is transferred to the standard model through a $CP\\ portal\\ interaction$, which we take to be a coupling of $\\chi$ to $\\tau$ leptons and an inert Higgs doublet. The CP asymmetry induced in left-handed $\\tau$ leptons biases sphalerons to produce the baryon asymmetry. The model has promising discovery potential at the LHC, while robustly providing a large enough baryon asymmetry and correct dark matter relic density with reasonable values of the couplings.

  11. Weakly-Coupled Higgs Bosons and Precision Electroweak Physics

    Energy Technology Data Exchange (ETDEWEB)

    Rowson, Peter C.

    2003-06-02

    We examine the prospects for discovering and elucidating the weakly-coupled Higgs sector at future collider experiments. The Higgs search consists of three phases: (i) discovery of a Higgs candidate, (ii) verification of the Higgs interpretation of the signal, and (iii) precision measurements of Higgs sector properties. The discovery of one Higgs boson with Standard Model properties is not sufficient to expose the underlying structure of the electroweak symmetry breaking dynamics. It is critical to search for evidence for a non-minimal Higgs sector and/or new physics associated with electroweak symmetry breaking dynamics. An improvement in precision electroweak data at future colliders can play a useful role in confirming the theoretical interpretation of the Higgs search results.

  12. Electroweak precision measurements at CLIC

    CERN Document Server

    Weber, Matthias Artur; Boyko, Igor

    2017-01-01

    The Compact Linear Collider (CLIC) is an option for a future electron-positron collider operating at centre-of-mass energies from a few hundred GeV up to 3 TeV. Details will be presented on two recent physics benchmark analyses of electroweak measurements at CLIC based on full detector simulations and assuming centre-of-mass energies of 1.4 and 3 TeV. Vector boson scattering gives insight into the mechanism of electroweak symmetry breaking. The processes e$^+$e$^-\\rightarrow$WW$\

  13. Two-Step Electroweak Baryogenesis

    CERN Document Server

    Inoue, Satoru; Ramsey-Musolf, Michael J

    2016-01-01

    We analyze electroweak baryogenesis during a two-step electroweak symmetry breaking transition, wherein the baryon asymmetry is generated during the first step and preserved during the second. Focusing on the dynamics of CP-violation required for asymmetry generation, we discuss general considerations for successful two-step baryogenesis. Using a concrete model realization, we illustrate in detail the viability of this scenario and the implications for present and future electric dipole moment (EDM) searches. We find that CP-violation associated with a partially excluded sector may yield the observed baryon asymmetry while evading present and future EDM constraints.

  14. Axiomatization of Special Relativity in First Order Logic

    Science.gov (United States)

    Luo, Yi-Chen; Chen, Lei; He, Wan-Ting; Ma, Yong-Ge; Zhang, Xin-Yu

    2016-07-01

    The axiomatization of physical theories is a fundamental issue of science. The first-order axiomatic system SpecRel for special relativity proposed recently by Andréka et al. is not enough to explain all the main results in the theory, including the twin paradox and energy-mass relation. In this paper, from a four-dimensional space-time perspective, we introduce the concepts of world-line, proper time and four-momentum to our axiomatic system SpecRel+. Then we introduce an axiom of mass (AxMass) and take four-momentum conservation as an axiom (AxCFM) in SpecRel+. It turns out that the twin paradox and energy-mass relation can be derived from SpecRel+ logically. Hence, as an extension of SpecRel, SpecRel+ is a suitable first-order axiomatic system to describe the kinematics and dynamics of special relativity. Supported by the National Science Foundation of China under Grant Nos. 11235003 and 11475023, National Social Sciences Foundation of China under Grant No. 14BZX078 and the Research Fund for the Doctoral Program of Higher Education of China, and the Undergraduate Training Program of Beijing

  15. First Order Deceptive Problem of ACO and Its Performance Analysis

    Directory of Open Access Journals (Sweden)

    Ling Chen

    2009-12-01

    Full Text Available Ant colony optimization(ACO, which is one of the intelligential optimization algorithm, has been widely used to solve combinational optimization problems. Deceptive problems have been considered difficult for ant colony optimization. It was believed that ACO will fail to converge to global optima of deceptive problems. This paper proves that the first order deceptive problem of ant colony algorithm satisfies value convergence under certain initial pheromone distribution, but does not satisfy solution convergence. We also present a first attempt towards the value-convergence time complexity analysis of ACO on the first-order deceptive systems taking the n-bit trap problem as the test instance. We prove that time complexity of MMAS, which is an ACO with limitations of the pheromone on each edge, on n-bit trap problem is O(n2m.log n, here n is the size of the problem and m is the number of artificial ants. Our experimental results confirm the correctness of our analysis.

  16. Electroweak Baryogenesis in R-symmetric Supersymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Fok, R.; Kribs, Graham D.; Martin, Adam; Tsai, Yuhsin

    2013-03-01

    We demonstrate that electroweak baryogenesis can occur in a supersymmetric model with an exact R-symmetry. The minimal R-symmetric supersymmetric model contains chiral superfields in the adjoint representation, giving Dirac gaugino masses, and an additional set of "R-partner" Higgs superfields, giving R-symmetric \\mu-terms. New superpotential couplings between the adjoints and the Higgs fields can simultaneously increase the strength of the electroweak phase transition and provide additional tree-level contributions to the lightest Higgs mass. Notably, no light stop is present in this framework, and in fact, we require both stops to be above a few TeV to provide sufficient radiative corrections to the lightest Higgs mass to bring it up to 125 GeV. Large CP-violating phases in the gaugino/higgsino sector allow us to match the baryon asymmetry of the Universe with no constraints from electric dipole moments due to R-symmetry. We briefly discuss some of the more interesting phenomenology, particularly of the of the lightest CP-odd scalar.

  17. Electroweak baryogenesis and primordial hypermagnetic fields

    CERN Document Server

    Piccinelli, Gabriella

    2004-01-01

    The origin of the matter-antimatter asymmetry of the universe remains one of the outstanding questions yet to be answered by modern cosmology and also one of only a handful of problems where the need of a larger number of degrees of freedom than those contained in the standard model (SM) is better illustrated. An appealing scenario for the generation of baryon number is the electroweak phase transition that took place when the temperature of the universe was about 100 GeV. Though in the minimal version of the SM, and without considering the interaction of the SM particles with additional degrees of freedom, this scenario has been ruled out given the current bounds for the Higgs mass, this still remains an open possibility in supersymmetric extensions of the SM. In recent years it has also been realized that large scale magnetic fields could be of primordial origin. A natural question is what effect, if any, these fields could have played during the electroweak phase transition in connection to the generation ...

  18. Gravitational waves as cosmological probes for new physics between the electroweak and the grand-unification scale

    Energy Technology Data Exchange (ETDEWEB)

    Sagunski, Laura

    2013-04-15

    Relic gravitational waves, generated by strongly first-order phase transitions in the early Universe, can serve as cosmological probes for new physics beyond the Standard Model. We investigate phase transitions at temperatures between the electroweak and the GUT scale in two extensions of the Standard Model for their possibility to provide detectable gravitational radiation. First, we study the Z{sub 2} symmetry breaking phase transition in the Standard model extended by a real gauge singlet. The analysis yields that the gravitational wave amplitude of the first-order phase transition with a thermally induced barrier is several orders too small for being detectable. The second model we discuss is a left-right symmetric model based on the gauge group SU(2){sub L} x SU(2){sub R} x U(1){sub B-L} generating a first-order phase transition already due to the emergence of a barrier in the tree-level potential. We derive an upper bound on the peak amplitude of the gravitational wave spectrum of the order h{sub o}{sup 2}{Omega}{sub GW} {approx_equal} 3 . 10{sup -11}. Hence, for very strong phase transitions a detection with the spaceborne interferometer LISA will be possible, whereas the sensitivity of the (cross-correlated) BBO detector will even allow to observe the gravitational wave spectrum within the whole parameter range of the model. By using the correlation between the characteristic parameters {alpha} and {beta} of the gravitational wave spectrum, we finally compute the lower bounds on {alpha}(T{sub *}) in dependence of the tunneling temperature T{sub *} which are necessary for a detection of the model spectrum by the specific detectors.

  19. Electroweak Physics at the LHC

    CERN Document Server

    Belloni, A; The ATLAS collaboration

    2012-01-01

    Slides to be presented at the Aspen 2012 workshop. Electroweak results from the ATLAS and CMS collaborations: W/Z inclusive and differential cross sections; W charge asymmetry and polarization; jet production in association with W and Z; di-boson cross-section measurements.

  20. Strong coupling electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Barklow, T.L. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Burdman, G. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics; Chivukula, R.S. [Boston Univ., MA (United States). Dept. of Physics

    1997-04-01

    The authors review models of electroweak symmetry breaking due to new strong interactions at the TeV energy scale and discuss the prospects for their experimental tests. They emphasize the direct observation of the new interactions through high-energy scattering of vector bosons. They also discuss indirect probes of the new interactions and exotic particles predicted by specific theoretical models.

  1. Electroweak results from hadron colliders

    Energy Technology Data Exchange (ETDEWEB)

    Marcel Demarteau

    1999-09-02

    A very brief summary of recent electroweak results from hadron colliders is given. The emphasis is placed on inclusive W{sup {+-}} and Z{sup 0} production, the measurement of the mass of the W boson and the measurement of trilinear gauge boson couplings.

  2. ELECTROWEAK MEASUREMENTS AT THE LHC

    CERN Document Server

    Savin, Alexander

    2017-01-01

    and dimuon decay channels are presented together with results on the effective mixing angle measurements. Angular coefficients measured in the Z boson production are compared with theoretical predictions. Electroweak production of the vector bosons in association with two jets is presented.

  3. Latest Electroweak Results from CDF

    Energy Technology Data Exchange (ETDEWEB)

    Lancaster, Mark

    2010-05-01

    The latest results in electroweak physics from proton anti-proton collisions at the Fermilab Tevatron recorded by the CDF detector are presented. The results provide constraints on parton distribution functions, the mass of the Higgs boson and beyond the Standard Model physics.

  4. A theory of first order dissipative superfluid dynamics

    CERN Document Server

    Bhattacharya, Jyotirmoy; Minwalla, Shiraz; Yarom, Amos

    2014-01-01

    We determine the most general form of the equations of relativistic superfluid hydrodynamics consistent with Lorentz invariance, the Onsager principle and the second law of thermodynamics at first order in the derivative expansion. Once parity is violated, either because the U(1) symmetry is anomalous or as a consequence of a different parity-breaking mechanism, our results deviate from the standard textbook analysis of superfluids. Our general equations require the specification of twenty parameters (such as the viscosity and conductivity). In the limit of small relative superfluid velocities we find a seven parameter set of equations. In the same limit, we have used the AdS/CFT correspondence to compute the parity odd contributions to the superfluid equations of motion for a generic holographic model and have verified that our results are consistent.

  5. FIRST-ORDER PARTICLE ACCELERATION IN MAGNETICALLY DRIVEN FLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Beresnyak, Andrey [Naval Research Laboratory, Washington, DC 20375 (United States); Li, Hui [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2016-03-10

    We demonstrate that particles are regularly accelerated while experiencing curvature drift in flows driven by magnetic tension. Some examples of such flows include spontaneous turbulent reconnection and decaying magnetohydrodynamic turbulence, where a magnetic field relaxes to a lower-energy configuration and transfers part of its energy to kinetic motions of the fluid. We show that this energy transfer, which normally causes turbulent cascade and heating of the fluid, also results in a first-order acceleration of non-thermal particles. Since it is generic, this acceleration mechanism is likely to play a role in the production of non-thermal particle distribution in magnetically dominant environments such as the solar chromosphere, pulsar magnetospheres, jets from supermassive black holes, and γ-ray bursts.

  6. First-order chemistry in the surface-flux layer

    DEFF Research Database (Denmark)

    Kristensen, L.; Andersen, C.E.; Ejsing Jørgensen, Hans

    1997-01-01

    process, The analytic flux solution showed a clear deviation from the constant flux, characterizing a conserved scalar in the surface-flux layer. It decreases with height and is reduced by an order of magnitude of the surface flux at a height equal to about the typical mean distance a molecule can travel...... before destruction. The predicted mean concentration profile, however, shows only a small deviation from the logarithmic behavior of a conserved scalar. The solution is consistent with assuming a flux-gradient relationship with a turbulent diffusivity corrected by the Damkohler ratio, the ratio...... of a characteristic turbulent time scale and the scalar mean lifetime. We show that if we use only first-order closure and neglect the effect of the Damkohler ratio on the turbulent diffusivity we obtain another analytic solution for the profiles of the flux and the mean concentration which, from an experimental...

  7. Basic first-order model theory in Mizar

    Directory of Open Access Journals (Sweden)

    Marco Bright Caminati

    2010-01-01

    Full Text Available The author has submitted to Mizar Mathematical Library a series of five articles introducing a framework for the formalization of classical first-order model theory.In them, Goedel's completeness and Lowenheim-Skolem theorems have also been formalized for the countable case, to offer a first application of it and to showcase its utility.This is an overview and commentary on some key aspects of this setup.It features exposition and discussion of a new encoding of basic definitions and theoretical gears needed for the task, remarks about the design strategies and approaches adopted in their implementation, and more general reflections about proof checking induced by the work done.

  8. Scattering from elastic sea beds: first-order theory.

    Science.gov (United States)

    Jackson, D R; Ivakin, A N

    1998-01-01

    A perturbation model for high-frequency sound scattering from an irregular elastic sea bed is considered. The sea bed is assumed homogeneous on the average and two kinds of irregularities are assumed to cause scattering: roughness of the water-sea bed interface and volume inhomogeneities of the sediment mass density and the speeds of compressional and shear waves. The first-order small perturbation approximation is used to obtain expressions for the scattering amplitude and bistatic scattering strength. The angular dependence of the scattering strength is calculated for sedimentary rock and the influence of shear elasticity is examined by comparison with the case of a fluid bottom. Shear effects are shown to be strong and complicated.

  9. Optimization Based Efficiencies in First Order Reliability Analysis

    Science.gov (United States)

    Peck, Jeffrey A.; Mahadevan, Sankaran

    2003-01-01

    This paper develops a method for updating the gradient vector of the limit state function in reliability analysis using Broyden's rank one updating technique. In problems that use commercial code as a black box, the gradient calculations are usually done using a finite difference approach, which becomes very expensive for large system models. The proposed method replaces the finite difference gradient calculations in a standard first order reliability method (FORM) with Broyden's Quasi-Newton technique. The resulting algorithm of Broyden updates within a FORM framework (BFORM) is used to run several example problems, and the results compared to standard FORM results. It is found that BFORM typically requires fewer functional evaluations that FORM to converge to the same answer.

  10. Constraint Propagation for Extended First-Order Logic

    CERN Document Server

    Wittocx, Johan; Bruynooghe, Maurice

    2010-01-01

    Constraint propagation is one of the basic forms of inference in many logic-based reasoning systems. In this paper, we investigate constraint propagation for first-order logic (FO), a suitable language to express a wide variety of constraints. We present an algorithm with polynomial time data-complexity for constraint propagation in the context of an FO theory and a finite structure. We show that constraint propagation in this manner can be represented by a datalog program and that the algorithm can be executed symbolically, i.e., independent of a finite structure. Next, we extend the algorithm to an extension of FO with inductive definitions and aggregates. Finally, we discuss several applications.

  11. Renormalization group analysis of the random first-order transition.

    Science.gov (United States)

    Cammarota, Chiara; Biroli, Giulio; Tarzia, Marco; Tarjus, Gilles

    2011-03-18

    We consider the approach describing glass formation in liquids as a progressive trapping in an exponentially large number of metastable states. To go beyond the mean-field setting, we provide a real-space renormalization group (RG) analysis of the associated replica free-energy functional. The present approximation yields in finite dimensions an ideal glass transition similar to that found in the mean field. However, we find that along the RG flow the properties associated with metastable glassy states, such as the configurational entropy, are only defined up to a characteristic length scale that diverges as one approaches the ideal glass transition. The critical exponents characterizing the vicinity of the transition are the usual ones associated with a first-order discontinuity fixed point.

  12. On First Order Optimality Conditions for Vector Optimization

    Institute of Scientific and Technical Information of China (English)

    L.M. Gra(n)a Drummond; A.N. Iusem; B.F. Svaiter

    2003-01-01

    We develop first order optimality conditions for constrained vector optimization. The partial orders for the objective and the constraints are induced by closed and convex cones with nonempty interior.After presenting some well known existence results for these problems, based on a scalarization approach, we establish necessity of the optimality conditions under a Slater-like constraint qualification, and then sufficiency for the K-convex case. We present two alternative sets of optimality conditions, with the same properties in connection with necessity and sufficiency, but which are different with respect to the dimension of the spaces to which the dual multipliers belong. We introduce a duality scheme, with a point-to-set dual objective, for which strong duality holds. Some examples and open problems for future research are also presented.

  13. Kinetics and thermodynamics of first-order Markov chain copolymerization

    Science.gov (United States)

    Gaspard, P.; Andrieux, D.

    2014-07-01

    We report a theoretical study of stochastic processes modeling the growth of first-order Markov copolymers, as well as the reversed reaction of depolymerization. These processes are ruled by kinetic equations describing both the attachment and detachment of monomers. Exact solutions are obtained for these kinetic equations in the steady regimes of multicomponent copolymerization and depolymerization. Thermodynamic equilibrium is identified as the state at which the growth velocity is vanishing on average and where detailed balance is satisfied. Away from equilibrium, the analytical expression of the thermodynamic entropy production is deduced in terms of the Shannon disorder per monomer in the copolymer sequence. The Mayo-Lewis equation is recovered in the fully irreversible growth regime. The theory also applies to Bernoullian chains in the case where the attachment and detachment rates only depend on the reacting monomer.

  14. Tracking control for first-order multi-agent systems

    Institute of Scientific and Technical Information of China (English)

    Yang LIU; Yingmin JIA

    2008-01-01

    In this paper,the conventional tracking control problem is expanded to first-order multi-agent systerns,which can be solved by directly guiding any agent in the group.The following three kinds of desired motions are considered for all agents to track:1)stillness in space,2)variable motion with known acceleration,3) variable motion with partly unknown acceleration.Specifically,fixed networks with time delays and switching networks without delays are both considered in case 1).Switching networks with and without time delays are both studied in case 2),while for 3),switching networks without delays are mainly investigated.A numerical simulation example is included to illustrate the results.

  15. Testing First-Order Logic Axioms in AutoCert

    Science.gov (United States)

    Ahn, Ki Yung; Denney, Ewen

    2009-01-01

    AutoCert [2] is a formal verification tool for machine generated code in safety critical domains, such as aerospace control code generated from MathWorks Real-Time Workshop. AutoCert uses Automated Theorem Provers (ATPs) [5] based on First-Order Logic (FOL) to formally verify safety and functional correctness properties of the code. These ATPs try to build proofs based on user provided domain-specific axioms, which can be arbitrary First-Order Formulas (FOFs). These axioms are the most crucial part of the trusted base, since proofs can be submitted to a proof checker removing the need to trust the prover and AutoCert itself plays the part of checking the code generator. However, formulating axioms correctly (i.e. precisely as the user had really intended) is non-trivial in practice. The challenge of axiomatization arise from several dimensions. First, the domain knowledge has its own complexity. AutoCert has been used to verify mathematical requirements on navigation software that carries out various geometric coordinate transformations involving matrices and quaternions. Axiomatic theories for such constructs are complex enough that mistakes are not uncommon. Second, adjusting axioms for ATPs can add even more complexity. The axioms frequently need to be modified in order to have them in a form suitable for use with ATPs. Such modifications tend to obscure the axioms further. Thirdly, speculating validity of the axioms from the output of existing ATPs is very hard since theorem provers typically do not give any examples or counterexamples.

  16. The sphaleron rate through the electroweak cross-over

    DEFF Research Database (Denmark)

    D'Onofrio, Michela; Rummukainen, Kari; Tranberg, Anders

    2012-01-01

    Using lattice simulations, we measure the sphaleron rate in the Standard Model as a function of temperature through the electroweak cross-over, for the Higgs masses m(H) = 115 and m(H) = 160GeV. We pay special attention to the shutting off of the baryon rate as the temperature is lowered. This qu......Using lattice simulations, we measure the sphaleron rate in the Standard Model as a function of temperature through the electroweak cross-over, for the Higgs masses m(H) = 115 and m(H) = 160GeV. We pay special attention to the shutting off of the baryon rate as the temperature is lowered....... This quantity enters computations of Baryogenesis via Leptogenesis, where non-zero lepton number is converted into non-zero baryon number by equilibrium sphaleron transitions. Combining existing numerical methods applicable in the symmetric and broken electroweak phases, we find the temperature dependence...... of the sphaleron rate at very high temperature, through the electroweak cross-over transition, and deep into the broken phase....

  17. A First-order Augmented Lagrangian Method for Compressed Sensing

    CERN Document Server

    Aybat, Necdet Serhat

    2010-01-01

    In this paper, we propose a first-order augmented Lagrangian algorithm (FAL) that solves the basis pursuit problem min{|x|_1: Ax = b} by inexactly solving a sequence of problems of the form min{lambda(k) |x|_1+ |Ax-b-lambda(k)theta(k)|_2^2}, for an appropriately chosen sequence of multipliers {lambda(k),theta(k)}. Each of these subproblems are solved using Algorithm 3 in [19] by Paul Tseng wherein each update reduces to "shrinkage" [12] or constrained "shrinkage". We show that FAL converges to an optimal solution x* of the basis pursuit problem, i.e. x*=argmin{|x|_1: Ax= b} and that there exist a priori fixed sequence {lambda(k)} such that for all epsilon>0, iterates x(k) computed by FAL are epsilon-feasible, i.e. |Ax(k) - b|_2 <= epsilon, and epsilon-optimal, | |x(k)|_1 - |x*|_1 | <= epsilon, after O(1/epsilon) iterations, where the complexity of each iteration is O(n log(n)). We also report the results of numerical experiments comparing the performance of FAL with SPA [1], NESTA [18], FPC [10, 11], FP...

  18. First order reversal curves diagrams for describing ferroelectric switching characteristics

    Directory of Open Access Journals (Sweden)

    Liliana Mitoseriu

    2009-06-01

    Full Text Available First Order Reversal Curves (FORC are polarization-field dependences described between saturation field Esat and a variable reversal field Er∈(-Esat, Esat. The FORC diagrams were proposed to describe some characteristics of the switching process in ferroelectrics. The approach is related to the Preisach model which considers the distribution of the elementary switchable units over their coercive and bias fields. The influence of the anisotropic porosity in Pb(Zr,TiO3 bulk ceramics on the FORC distributions demonstrated the existence of a positive/negative bias as a result of the confinement induced by anisotropy. The reducing of grain size in Ba(Zr,TiO3 ceramics causes an increase of the ratio of the reversible/irreversible components of the polarization on the FORC distribution indicating the tendency of system towards the superparaelectric state. The FORC method demonstrates to provide a kind of ‘fingerprinting’ of various types of switching characteristics in ferroic systems.

  19. A first-order approach to conformal gravity

    CERN Document Server

    Zlosnik, T G

    2016-01-01

    We investigate whether a spontaneously-broken gauge theory of the group $SU(2,2)$ may be a genuine competitor to General Relativity. The basic ingredients of the theory are an $SU(2,2)$ gauge field $A_{\\mu}$ and a Higgs field $W$ in the adjoint representation of the group with the Higgs field producing the symmetry breaking $SU(2,2)\\rightarrow SO(1,3)\\times SO(1,1)$. The action for gravity is polynomial in $\\{A_{\\mu},W\\}$ and the field equations are first-order in derivatives of these fields. The new $SO(1,1)$ symmetry in the gravitational sector is interpreted in terms of an emergent scale symmetry and the recovery of conformalized General Relativity and fourth-order Weyl conformal gravity as limits of the theory- following imposition of Lagrangian constraints- is demonstrated. Maximally symmetric spacetime solutions to the full theory are found and stability of the theory around these solutions is investigated; it is shown that regions of the theory's parameter space describe perturbations identical to that...

  20. A test of first order scaling in Nf=2 QCD

    CERN Document Server

    Cossu, G; Di Giacomo, A; Pica, C

    2007-01-01

    We complete our analysis of Nf=2 QCD based on the lattice staggered fermion formulation. Using a series of Monte Carlo simulations at fixed (amq*Ls^yh) one is able to test the universality class with given critical exponent yh. This strategy has been used to test the O(4) universality class and it has been presented at the previous Lattice conferences. No agreement was found with simulations in the mass range amq=[0.01335,0.15] using lattices with Ls=16 up to 32 and Lt=4. With the same strategy, we now investigate the possibility of a first order transition using a new set of Monte Carlo data corresponding to yh=3 in the same mass and volume range as the one used for O(4). A substantial agreement is observed both in the specific heat scaling and in the scaling of the chiral condensate, while the chiral susceptibilities still presents visible deviation from scaling in the mass range explored.

  1. Energy in first order 2+1 gravity

    CERN Document Server

    Corichi, Alejandro

    2015-01-01

    We consider \\Lambda=0 three dimensional gravity with asymptotically flat boundary conditions. This system was studied by Ashtekar and Varadarajan within the second order formalism -with metric variables- who showed that the Regge-Teitelboim formalism yields a consistent Hamiltonian description where, surprisingly, the energy is bounded from below and from above. The energy of the spacetime is, however, determined up to an arbitrary constant. The natural choice was to fix that freedom such that Minkowski spacetime has zero energy. More recently, Marolf and Pati\\~no started from the Einstein-Hilbert action supplemented with the Gibbons-Hawking term and showed that, in the 2+1 decomposition of the theory, the energy is shifted from the Ashtekar-Varadarajan analysis in such a way that Minkowski spacetime possesses a negative energy. In this contribution we consider the first order formalism, where the fundamental variables are a so(2,1) connection $\\omega_a{^I}_J$ and a triad $e_a^I$. We consider two actions. A n...

  2. Statistical properties of first-order bang-bang Pll with nonzero loop delay

    OpenAIRE

    Chun, Byungjin; Kennedy, Michael Peter

    2008-01-01

    A method to solve the stationary state probability is presented for the first-order bang-bang phase-locked loop (BBPLL) with nonzero loop delay. This is based on a delayed Markov chain model and a state How diagram for tracing the state history due to the loop delay. As a result, an eigenequation is obtained, and its closed form solutions are derived for some cases. After obtaining the state probability, statistical characteristics such as mean gain of the binary phase detector and timing err...

  3. Unanswered Questions in the Electroweak Theory

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, Chris

    2009-11-01

    This article is devoted to the status of the electroweak theory on the eve of experimentation at CERN's Large Hadron Collider. A compact summary of the logic and structure of the electroweak theory precedes an examination of what experimental tests have established so far. The outstanding unconfirmed prediction of the electroweak theory is the existence of the Higgs boson, a weakly interacting spin-zero particle that is the agent of electroweak symmetry breaking, the giver of mass to the weak gauge bosons, the quarks, and the leptons. General arguments imply that the Higgs boson or other new physics is required on the TeV energy scale. Indirect constraints from global analyses of electroweak measurements suggest that the mass of the standard-model Higgs boson is less than 200 GeV. Once its mass is assumed, the properties of the Higgs boson follow from the electroweak theory, and these inform the search for the Higgs boson. Alternative mechanisms for electroweak symmetry breaking are reviewed, and the importance of electroweak symmetry breaking is illuminated by considering a world without a specific mechanism to hide the electroweak symmetry. For all its triumphs, the electroweak theory has many shortcomings.

  4. Electroweak Physics at the LHC

    CERN Document Server

    Brandt, Gerhard; The ATLAS collaboration

    2017-01-01

    This talk summarises results on electroweak processes at the Large Hadron Collider by the ATLAS and CMS collaborations. It covers results from sqrt(s) = 7, 8 TeV data from LHC Run-1, and also results using sqrt(s) = 13 TeV data from the recent LHC Run-2. The status of cross section measurements of single and di-boson production, as well as rare electroweak processes such as vector boson scattering and tri- boson production are presented. Processes that can not be observed (yet) allow to set limits on the respective cross sections. All observations are compatible with Standard Model descriptions and allow to constrain new physics which would manifest through extra gauge couplings, or Standard Model gauge couplings deviating from their predicted value. Limits on such anomalous gauge couplings are derived.

  5. Electroweak relaxation from finite temperature

    CERN Document Server

    Hardy, Edward

    2015-01-01

    We study theories which naturally select a vacuum with parametrically small Electroweak Scale due to finite temperature effects in the early universe. In particular, there is a scalar with an approximate shift symmetry broken by a technically natural small coupling to the Higgs, and a temperature dependent potential. As the temperature of the universe drops, the scalar follows the minimum of its potential altering the Higgs mass squared parameter. The scalar also has a periodic potential with amplitude proportional to the Higgs expectation value, which traps it in a vacuum with a small Electroweak Scale. The required temperature dependence of the potential can occur through strong coupling effects in a hidden sector that are suppressed at high temperatures. Alternatively, it can be generated perturbatively from a one-loop thermal potential. In both cases, for the scalar to be displaced, a hidden sector must be reheated to temperatures significantly higher than the visible sector. However this does not violate...

  6. Electroweak Vortices and Gauge Equivalence

    Science.gov (United States)

    MacDowell, Samuel W.; Törnkvist, Ola

    Vortex configurations in the electroweak gauge theory are investigated. Two gauge-inequivalent solutions of the field equations, the Z and W vortices, have previously been found. They correspond to embeddings of the Abelian Nielsen-Olesen vortex solution into a U(1) subgroup of SU(2)×U(1). It is shown here that any electroweak vortex solution can be mapped into a solution of the same energy with a vanishing upper component of the Higgs field. The correspondence is a gauge equivalence for all vortex solutions except those for which the winding numbers of the upper and lower Higgs components add to zero. This class of solutions, which includes the W vortex, corresponds to a singular solution in the one-component gauge. The results, combined with numerical investigations, provide an argument against the existence of other vortex solutions in the gauge-Higgs sector of the Standard Model.

  7. First order Bragg grating filters in silicon on insulator waveguides

    Science.gov (United States)

    Waugh, Peter Michael

    2008-08-01

    The subject of this project is the design; analysis, fabrication and characterisation of first order Bragg Grating optical filters in Silicon-on-Insulator (SOI) planar waveguides. It is envisaged that this work will result in the possibility of Bragg Grating filters for use in Silicon Photonics. It is the purpose of the work to create as far as is possible flat surface waveguides so as to facilitate Thermo-Optic tuning and also the incorporation into rib-waveguide Silicon Photonics. The spectral response of the shallow Bragg Gratings was modelled using Coupled Mode Theory (CMT) by way of RSoft Gratingmod TM. Also the effect of having a Bragg Grating with alternate layers of refractive index of 1.5 and 3.5 was simulated in order to verify that Silica and Silicon layered Bragg Gratings could be viable. A series of Bragg Gratings were patterned on 1.5 micron SOI at Philips in Eindhoven, Holland to investigate the variation of grating parameters with a) the period of the gratings b) the mark to space ratio of the gratings and c) the length of the region converted to Bragg Gratings (i.e. the number of grating period repetitions). One set of gratings were thermally oxidised at Philips in Eindhoven and another set were ion implanted with Oxygen ions at the Ion Beam Facility, University of Surrey, England. The gratings were tested and found to give transmission minima at approximately 1540 nanometres and both methods of creating flat surfaces were found to give similar minima. Atomic Force Microscopy was applied to the grating area of the as-implanted samples in the Advanced Technology Institute, University of Surrey, which were found to have surface undulations in the order of 60 nanometres.

  8. Fit to Electroweak Precision Data

    CERN Document Server

    Erler, J

    2006-01-01

    A brief review of electroweak precision data from LEP, SLC, the Tevatron, and low energies is presented. The global fit to all data including the most recent results on the masses of the top quark and the W boson reinforces the preference for a relatively light Higgs boson. I will also give an outlook on future developments at the Tevatron Run II, CEBAF, the LHC, and the ILC.

  9. Electroweak measurements at the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Jose E.; /INFN, Pisa

    2006-06-01

    Recent Electroweak measurements by the CDF and D0 collaborations in p{bar p} collisions {radical}s = 1.96 TeV are presented here. Measurements of W, Z and diboson production cross sections as well as W asymmetry using integrated luminosities up to 800 pb{sup -1} are reviewed. Limits on triple gauge anomalous couplings on diboson production are discussed elsewhere.

  10. Models of electroweak symmetry breaking

    CERN Document Server

    Pomarol, Alex

    2015-01-01

    This chapter present models of electroweak symmetry breaking arising from strongly interacting sectors, including both Higgsless models and mechanisms involving a composite Higgs. These scenarios have also been investigated in the framework of five-dimensional warped models that, according to the AdS/CFT correspondence, have a four-dimensional holographic interpretation in terms of strongly coupled field theories. We explore the implications of these models at the LHC.

  11. LHCb: Electroweak studies at LHCb

    CERN Multimedia

    Salustino Guimaraes, V

    2012-01-01

    Results on the measurement of the $W^{\\pm}$ and $Z^{0}$ cross-sections are presented using final state leptons with pseudorapidities between 2 and 4.5. Due to its acceptance, LHCb can probe a regime of low low-x electroweak boson production, where parton distribution functions are not well constrained. We summarize the $W^{\\pm}$ measurements performed in the decay $\\mu^{\\pm}\

  12. Topology of the Electroweak Vacua

    CERN Document Server

    Gripaios, Ben

    2016-01-01

    In the Standard Model, the electroweak symmetry is broken by a complex, $SU(2)$-doublet Higgs field and the vacuum manifold $SU(2)\\times U(1)/U(1)$ has the topology of a 3-sphere. We remark that there exist alternative effective field theory descriptions that can be fully consistent with existing collider data, but in which the vacuum manifold is homeomorphic to an arbitrary non-trivial principal $U(1)$-bundle over a 2-sphere. These alternatives have non-trivial fundamental group and so lead to topologically-stable electroweak strings. Perhaps the most plausible alternative to $S^3$ is the manifold $\\mathbb{R}P^3$ (with fundamental group $\\mathbb{Z}/2$), since it allows custodial protection of gauge boson masses and their couplings to fermions. Searches for such strings may thus be regarded as independent, and qualitatively different, precision tests of the SM, in that they are (thus far) astrophysical in nature, and test the global topology, rather than the local geometry, of the electroweak vacua.

  13. A Polarimetric First-Order Model of Soil Moisture Effects on the DInSAR Coherence

    Directory of Open Access Journals (Sweden)

    Simon Zwieback

    2015-06-01

    Full Text Available Changes in soil moisture between two radar acquisitions can impact the observed coherence in differential interferometry: both coherence magnitude |Υ| and phase Φ are affected. The influence on the latter potentially biases the estimation of deformations. These effects have been found to be variable in magnitude and sign, as well as dependent on polarization, as opposed to predictions by existing models. Such diversity can be explained when the soil is modelled as a half-space with spatially varying dielectric properties and a rough interface. The first-order perturbative solution achieves–upon calibration with airborne L band data–median correlations ρ at HH polarization of 0.77 for the phase Φ, of 0.50 for |Υ|, and for the phase triplets ≡ of 0.56. The predictions are sensitive to the choice of dielectric mixing model, in particular the absorptive properties; the differences between the mixing models are found to be partially compensatable by varying the relative importance of surface and volume scattering. However, for half of the agricultural fields the Hallikainen mixing model cannot reproduce the observed sensitivities of the phase to soil moisture. In addition, the first-order expansion does not predict any impact on the HV coherence, which is however empirically found to display similar sensitivities to soil moisture as the co-pol channels HH and VV. These results indicate that the first-order solution, while not able to reproduce all observed phenomena, can capture some of the more salient patterns of the effect of soil moisture changes on the HH and VV DInSAR signals. Hence it may prove useful in separating the deformations from the moisture signals, thus yielding improved displacement estimates or new ways for inferring soil moisture.

  14. Stabilizing the electroweak vacuum by higher dimensional operators in a Higgs-Yukawa model

    Energy Technology Data Exchange (ETDEWEB)

    Hegde, Prasad [National Taiwan Univ., Taipei (China); Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Lin, C.J. David [National Chaio Tung Univ., Hsinchu (China); Nagy, Attila [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany)

    2013-11-15

    The Higgs boson discovery at the LHC with a mass of approximately 126 GeV suggests, that the electroweak vacuum of the standard model may be metastable at very high energies. However, any new physics beyond the standard model can change this picture. We want to address this important question within a lattice Higgs-Yukawa model as the limit of the standard model (SM). In this framework we will probe the effect of a higher dimensional operator for which we take a ({phi}{sup {dagger}}{phi}){sup 3}-term. Such a term could easily originate as a remnant of physics beyond the SM at very large scales. As a first step we investigate the phase diagram of the model including such a ({phi}{sup {dagger}}{phi}){sup 3} operator. Exploratory results suggest the existence of regions in parameter space where first order transitions turn to second order ones, indicating the existence of a tri-critical line. We will explore the phase structure and the consequences for the stability of the SM, both analytically by investigating the constraint effective potential in lattice perturbation theory, and by studying the system non-perturbatively using lattice simulations.

  15. Early Electroweak Measurements in CMS and ATLAS

    CERN Document Server

    Alcaraz, J

    2007-01-01

    Electroweak processes will be extremely important during the first phases of the LHC programme. They will be used to calibrate the ATLAS and CMS detectors, to understand the underlying event environment and to obtain background control samples for a large variety of possible new-physics signals. A progressive scenario can be envisaged: large statistics samples of W and Z decays into leptons will be available for an integrated luminosity of 10 /pb. W and Z production accompanied by jets will be studied with 100 /pb, diboson signals like pp->WZ will be observable with 150 /pb and a detailed understanding of the detector performance using ttbar events could be possible with luminosities as low as 300 /pb. Exploiting such a rich scenario is one of the objectives and challenges for the first year of LHC operation.

  16. The hierarchy problem of the electroweak standard model revisited

    Energy Technology Data Exchange (ETDEWEB)

    Jegerlehner, Fred [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2013-05-15

    A careful renormalization group analysis of the electroweak Standard Model reveals that there is no hierarchy problem in the SM. In the broken phase a light Higgs turns out to be natural as it is self-protected and self-tuned by the Higgs mechanism. It means that the scalar Higgs needs not be protected by any extra symmetry, specifically super symmetry, in order not to be much heavier than the other SM particles which are protected by gauge- or chiral-symmetry. Thus the existence of quadratic cutoff effects in the SM cannot motivate the need for a super symmetric extensions of the SM, but in contrast plays an important role in triggering the electroweak phase transition and in shaping the Higgs potential in the early universe to drive inflation as supported by observation.

  17. Catalysis of Electroweak Baryogenesis via Fermionic Higgs Portal Dark Matter

    CERN Document Server

    Chao, Wei

    2015-01-01

    We investigate catalysis of electroweak baryogenesis by fermionic Higgs portal dark matter using a two Higgs doublet model augmented by vector-like fermions. The lightest neutral fermion mass eigenstate provides a viable dark matter candidate in the presence of a stabilizing symmetry Z_2 or gauged U(1)_D symmetry. Allowing for a non-vanishing CP-violating phase in the lowest-dimension Higgs portal dark matter interactions allows generation of the observed dark matter relic density while evading direct detection bounds. The same phase provides a source for electroweak baryogenesis. We show that it is possible to obtain the observed abundances of visible and dark matter while satisfying present bounds from electric dipole moment (EDM) searches and direct detection experiments. Improving the present electron (neutron) EDM sensitivity by one (two) orders of magnitude would provide a conclusive test of this scenario.

  18. New Gain Controllable Resistor-less Current-mode First Order Allpass Filter and its Application

    Directory of Open Access Journals (Sweden)

    W. Jaikla

    2012-04-01

    Full Text Available New first order allpass filter (APF in current mode, constructed from 2 CCCCTAs and grounded capacitor, is presented. The current gain and phase shift can be electronically /orthogonally controlled. Low input and high output impedances are achieved which make the circuit to be easily cascaded to the current-mode circuit without additional current buffers. The operation of the proposed filter has been verified through simulation results which confirm the theoretical analysis. The application example as current-mode quadrature oscillator with non-interactive current control for both of oscillation condition and oscillation frequency is included to show the usability of the proposed filter.

  19. First-order layering and critical wetting transitions in nonadditive hard-sphere mixtures.

    Science.gov (United States)

    Hopkins, Paul; Schmidt, Matthias

    2011-05-01

    Using fundamental-measure density functional theory we investigate entropic wetting in an asymmetric binary mixture of hard spheres with positive nonadditivity. We consider a general planar hard wall, where preferential adsorption is induced by a difference in closest approach of the different species and the wall. Close to bulk fluid-fluid coexistence, the phase rich in the minority component adsorbs either through a series of first-order layering transitions, where an increasing number of liquid layers adsorbs sequentially, or via a critical wetting transition, where a thick film grows continuously.

  20. Weak first-order orientational transition in the Lebwohl-Lasher model for liquid crystals

    DEFF Research Database (Denmark)

    Zhang, Zhengping; Mouritsen, Ole G.; Zuckermann, Martin J.

    1992-01-01

    The nature of the orientational phase transition in the three-dimensional Lebwohl-Lasher model of liquid crystals has been studied by computer simulation using reweighting techniques and finite-size scaling analysis. Unambiguous numerical evidence is found in favor of a weak first-order transition...... and the presence of pseudospinodal points, T±*, which are extremely close to the equilibrium transition temperature, ‖Tc-T±*‖/Tc≲0.5×10-3, in good agreement with experimental data for the nematic-isotropic transition....

  1. Electroweak breaking in supersymmetric models

    CERN Document Server

    Ibáñez, L E

    1992-01-01

    We discuss the mechanism for electroweak symmetry breaking in supersymmetric versions of the standard model. After briefly reviewing the possible sources of supersymmetry breaking, we show how the required pattern of symmetry breaking can automatically result from the structure of quantum corrections in the theory. We demonstrate that this radiative breaking mechanism works well for a heavy top quark and can be combined in unified versions of the theory with excellent predictions for the running couplings of the model. (To be published in ``Perspectives in Higgs Physics'', G. Kane editor.)

  2. ELECTROWEAK PHYSICS AND PRECISION STUDIES.

    Energy Technology Data Exchange (ETDEWEB)

    MARCIANO, W.

    2005-10-24

    The utility of precision electroweak measurements for predicting the Standard Model Higgs mass via quantum loop effects is discussed. Current values of m{sub W}, sin{sup 2} {theta}{sub W}(m{sub Z}){sub {ovr MS}} and m{sub t} imply a relatively light Higgs which is below the direct experimental bound but possibly consistent with Supersymmetry expectations. The existence of Supersymmetry is further suggested by a 2{sigma} discrepancy between experiment and theory for the muon anomalous magnetic moment. Constraints from precision studies on other types of ''New Physics'' are also briefly described.

  3. History of electroweak symmetry breaking

    CERN Document Server

    Kibble, T W B

    2015-01-01

    In this talk, I recall the history of the development of the unified electroweak theory, incorporating the symmetry-breaking Higgs mechanism, as I saw it from my standpoint as a member of Abdus Salam's group at Imperial College. I start by describing the state of physics in the years after the Second World War, explain how the goal of a unified gauge theory of weak and electromagnetic interactions emerged, the obstacles encountered, in particular the Goldstone theorem, and how they were overcome, followed by a brief account of more recent history, culminating in the historic discovery of the Higgs boson in 2012.

  4. Electroweak precision measurements in ATLAS

    CERN Document Server

    Soldatov, Evgeny; The ATLAS collaboration

    2017-01-01

    The ATLAS collaboration has performed detailed measurements of integrated and differential cross sections of the production of heavy bosons and of di-boson pairs in fully-leptonic and semi-leptonic final states at centre-of-mass energies of 8 and 13 TeV. These measurements o constitute stringent tests of the electroweak sector of the Standard Model and provide a model-independent means to search for new physics at the TeV scale. The results are compared to predictions at NLO (and NNLO) in pQCD and provide constraints on new physics, by setting limits on anomalous triple gauge couplings.

  5. Electroweak precision measurements in CMS

    CERN Document Server

    Dordevic, Milos

    2017-01-01

    An overview of recent results on electroweak precision measurements from the CMS Collaboration is presented. Studies of the weak boson differential transverse momentum spectra, Z boson angular coefficients, forward-backward asymmetry of Drell-Yan lepton pairs and charge asymmetry of W boson production are made in comparison to the state-of-the-art Monte Carlo generators and theoretical predictions. The results show a good agreement with the Standard Model. As a proof of principle for future W mass measurements, a W-like analysis of the Z boson mass is performed.

  6. The nature of the first order isostructural transition in GdRhSn

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Sachin [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Suresh, K.G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Nigam, A.K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Mudryk, Y.; Paudyal, D. [Ames Laboratory, Iowa State University, Ames, IA 50011-3020 (United States); Pecharsky, V.K.; Gschneidner, K.A. [Ames Laboratory, Iowa State University, Ames, IA 50011-3020 (United States); Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011-2300 (United States)

    2014-11-15

    Highlights: • GdRhSn has been studied by means of different measurements and shows an iso-structural transition in paramagnetic regime. • Experimental and theoretical studies confirm the iso-structural transition in paramagnetic regime. • The change in unit cell volume is discontinuous which reveals the first order nature of iso-structural transition. • The compound also shows considerable MCE around its ordering temperature. - Abstract: We present structural, magnetic, thermal, magnetocaloric, and electrical transport properties of polycrystalline GdRhSn. Magnetization data show that it orders antiferromagnetically at T{sub N} = 16.2 K. The compound has the ZrNiAl type hexagonal crystal structure at room temperature and undergoes a first order iso-structural transition in the paramagnetic state at 245 K. The unit cell volume change at the transition is small (−0.07%) but discontinuous, in agreement with the first-order nature of the transition observed by magnetic, transport, and heat capacity measurements. The anisotropic changes of the lattice parameters are Δa/a = 0.28% and Δc/c = −0.64% on cooling. A substantial change in the 4f and conduction electron hybridization, giving rise to an increased integrated DOS, occurs when the high temperature phase transforms to the low temperature phase. A moderate magnetocaloric effect at T{sub N} (ΔS{sub M} = −6.5 J/kg K and ΔT{sub ad} = 4.5 K for ΔH = 50 kOe) has been measured using both magnetization and heat capacity data.

  7. The nature of the first order isostructural transition in GdRhSn

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Sachin [Indian Institute of Technology Bombay; Suresh, K G [Indian Institute of Technology Bombay; Nigam, A K [Tara Institute of Fundamental Resarch; Mudryk, Y [Ames Laboratory; Paudyal, D [Ames Laboratory; Pecharsky, V K [Ames Laboratory; Gschneidner, Karl A [Ames Laboratory

    2014-11-01

    We present structural, magnetic, thermal, magnetocaloric, and electrical transport properties of polycrystalline GdRhSn. Magnetization data show that it orders antiferromagnetically at TN = 16.2 K. The compound has the ZrNiAl type hexagonal crystal structure at room temperature and undergoes a first order iso-structural transition in the paramagnetic state at 245 K. The unit cell volume change at the transition is small (-0.07 %) but discontinuous, in agreement with the first-order nature of the transition observed by magnetic, transport, and heat capacity measurements. The anisotropic changes of the lattice parameters are Δa/a = 0.28 % and Δc/c = -0.64 % on cooling. A substantial change in the 4f and conduction electron hybridization, giving rise to an increased integrated DOS, occurs when the high temperature phase transforms to the low temperature phase. A moderate magnetocaloric effect at TN (ΔSM = -6.5 J/kg K and ΔTad = 4.5 K for ΔH= 50 kOe) has been measured using both magnetization and heat capacity data

  8. Dynamics of a first-order transition to an absorbing state

    Science.gov (United States)

    Néel, Baptiste; Rondini, Ignacio; Turzillo, Alex; Mujica, Nicolás; Soto, Rodrigo

    2014-04-01

    A granular system confined in a quasi-two-dimensional box that is vertically vibrated can transit to an absorbing state in which all particles bounce vertically in phase with the box, with no horizontal motion. In principle, this state can be reached for any density lower than the one corresponding to one complete monolayer, which is then the critical density. Below this critical value, the transition to the absorbing state is of first order, with long metastable periods, followed by rapid transitions driven by homogeneous nucleation. Molecular dynamics simulations and experiments show that there is a dramatic increase on the metastable times far below the critical density; in practice, it is impossible to observe spontaneous transitions close to the critical density. This peculiar feature is a consequence of the nonequilibrium nature of this first-order transition to the absorbing state. A Ginzburg-Landau model, with multiplicative noise, describes qualitatively the observed phenomena and explains the macroscopic size of the critical nuclei. The nuclei become of small size only close to a second critical point where the active phase becomes unstable via a saddle node bifurcation. It is only close to this second critical point that experiments and simulations can evidence spontaneous transitions to the absorbing state while the metastable times grow dramatically moving away from it.

  9. Electroweak relaxation from finite temperature

    Science.gov (United States)

    Hardy, Edward

    2015-11-01

    We study theories which naturally select a vacuum with parametrically small Electroweak Scale due to finite temperature effects in the early universe. In particular, there is a scalar with an approximate shift symmetry broken by a technically natural small coupling to the Higgs, and a temperature dependent potential. As the temperature of the universe drops, the scalar follows the minimum of its potential altering the Higgs mass squared parameter. The scalar also has a periodic potential with amplitude proportional to the Higgs expectation value, which traps it in a vacuum with a small Electroweak Scale. The required temperature dependence of the potential can occur through strong coupling effects in a hidden sector that are suppressed at high temperatures. Alternatively, it can be generated perturbatively from a one-loop thermal potential. In both cases, for the scalar to be displaced, a hidden sector must be reheated to temperatures significantly higher than the visible sector. However this does not violate observational constraints provided the hidden sector energy density is transferred to the visible sector without disrupting big bang nucleosynthesis. We also study how the mechanism can be implemented when the visible sector is completed to the Minimal Supersymmetric Standard Model at a high scale. Models with a UV cutoff of 10 TeV and no fields taking values over a range greater than 1012 GeV are possible, although the scalar must have a range of order 108 times the effective decay constant in the periodic part of its potential.

  10. First-order superconducting transition in the inter-band model

    Energy Technology Data Exchange (ETDEWEB)

    Gomes da Silva, M. [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-00 Manaus, AM (Brazil); Instituto Federal de Educação Ciência e Tecnologia do Amazonas, Av. 7 de Setembro, 1975 - Centro, Manaus, AM 69020-120 (Brazil); Dinóla Neto, F., E-mail: dinola@ufam.edu.br [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-00 Manaus, AM (Brazil); Padilha, I.T. [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-00 Manaus, AM (Brazil); Ricardo de Sousa, J. [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-00 Manaus, AM (Brazil); National Institute of Science and Technology for Complex Systems, Universidade Federal do Amazonas, 3000, Japiim, 69077-000 Manaus, AM (Brazil); Continentino, M.A. [Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, RJ (Brazil)

    2014-04-01

    The comprehension about the theoretical features of superconductivity is an interesting and fundamental topic in condensed matter physics. Several theoretical proposals were considered to describe the new classes of superconducting compounds and alloys. In this work we propose to study a non-conventional superconducting system where the Cooper pairs are formed by fermions from different bands described via two band model with hybridization. In this inter-band scenario we find a first-order phase transition at low temperatures and we observe a tricritical point in the phase diagram. In our description, the control parameter is the hybridization that can be tuned by external pressure. This fact indicates the possibility to observe discontinuities in the SC gap amplitude through applying pressure on the system.

  11. Dynamo onset as a first-order transition: lessons from a shell model for magnetohydrodynamics.

    Science.gov (United States)

    Sahoo, Ganapati; Mitra, Dhrubaditya; Pandit, Rahul

    2010-03-01

    We carry out systematic and high-resolution studies of dynamo action in a shell model for magnetohydrodynamic (MHD) turbulence over wide ranges of the magnetic Prandtl number PrM and the magnetic Reynolds number ReM. Our study suggests that it is natural to think of dynamo onset as a nonequilibrium first-order phase transition between two different turbulent, but statistically steady, states. The ratio of the magnetic and kinetic energies is a convenient order parameter for this transition. By using this order parameter, we obtain the stability diagram (or nonequilibrium phase diagram) for dynamo formation in our MHD shell model in the (PrM-1,ReM) plane. The dynamo boundary, which separates dynamo and no-dynamo regions, appears to have a fractal character. We obtain a hysteretic behavior of the order parameter across this boundary and suggestions of nucleation-type phenomena.

  12. 6th Conference and Workshop on Strong and Electroweak Matter

    CERN Document Server

    Kainulainen, Kimmo; Kajantie, Keijo; Rummukainen, Kari; Strong and Electroweak Matter 2004; SEWM 2004

    2004-01-01

    This volume presents an authoritative review of the physics of strongly and electroweakly interacting elementary particle matter in extreme conditions that prevailed in the very early Universe, and which are being recreated in high energy physics laboratories today. Exciting, high-quality experimental results from RHIC collider at Brookhaven, collected since summer 2000, suggest that strongly interacting quark-gluon plasma has indeed been produced. The study of these phenomena will form an important part of theoretical particle and nuclear physics for years to come. Based on the discussions of more than a hundred experts at the Strong and Electroweak Matter 2004 Meeting, this volume contains an up-to-date overview of present ideas on QCD matter: quark-gluon plasma in heavy ion collisions, phase structure, kinetics, thermalization and transport properties. Also discussed are topics related to the cosmology of the early Universe, dark matter, inflation and creation of particle-antiparticle asymmetries. Both an...

  13. Electroweak couplings of the lepton

    Indian Academy of Sciences (India)

    John Swain

    2000-04-01

    The tau lepton is the heaviest known lepton and studies of its production and decay allow measurements of its couplings to the electroweak gauge bosons. In particular, sensitive tests of the idea of lepton universality are possible, with the hope that some light will be shed on not just the nature of the origin of mass, but also on why there seem to be three generations. The recent LEP results provide most of this experimental data, and very recently measurements of the anomalous magnetic and electric dipole moments of the tau have been performed. I present an overview of all these results, and discuss what this means in the framework of the Standard Model and attempts to go beyond it.

  14. A gravitating electroweak bag model

    Science.gov (United States)

    Burinskii, Alexander

    2016-02-01

    Gravitational and electromagnetic (EM) field of electron is described by the Kerr-Newman (KN) black hole solution with a topological defect. Regularization of this defect by the Higgs field leads to the smooth source which shares much in common with the known MIT- and SLAC- bag models, but has the advantage, of matching gravitational and electromagnetic fields of the electron. This model is flexible, and the rotating KN bag takes the shape of a thin disk with a circular string positioned on the sharp border of the disk. We consider the lowest excitations of the KN solution and the corresponding deformations of the bag surface, setting a preliminary correspondence with electroweak sector of the SM.

  15. Classical issues in electroweak baryogenesis

    CERN Document Server

    Smit, J; Smit, Jan; Tranberg, Anders

    2004-01-01

    In one scenario of baryogenesis, the matter-antimatter asymmetry was generated in the early universe during a cold electroweak transition. We model this transition by changing the sign of the effective mass-squared parameter of the Higgs field from positive to negative. The resulting `tachyonic' instability leads to a rapid growth of occupation numbers, such that a classical approximation can be made in computing subsequent developments in real time. We solve the classical equations of motion in the SU(2)-Higgs model under the influence of effective CP-violation. The resulting baryon asymmetry follows from the generated Chern-Simons number using the anomaly equation. The `classical' difficulties with lattice implementations of these observables are avoided here because the fields are smooth on the lattice scale.

  16. The reversibility and first-order nature of liquid-liquid transition in a molecular liquid

    Science.gov (United States)

    Kobayashi, Mika; Tanaka, Hajime

    2016-11-01

    Liquid-liquid transition is an intriguing phenomenon in which a liquid transforms into another liquid via the first-order transition. For molecular liquids, however, it always takes place in a supercooled liquid state metastable against crystallization, which has led to a number of serious debates concerning its origin: liquid-liquid transition versus unusual nano-crystal formation. Thus, there have so far been no single example free from such debates, to the best of our knowledge. Here we show experimental evidence that the transition is truly liquid-liquid transition and not nano-crystallization for a molecular liquid, triphenyl phosphite. We kinetically isolate the reverse liquid-liquid transition from glass transition and crystallization with a high heating rate of flash differential scanning calorimetry, and prove the reversibility and first-order nature of liquid-liquid transition. Our finding not only deepens our physical understanding of liquid-liquid transition but may also initiate a phase of its research from both fundamental and applications viewpoints.

  17. First order resonance overlap and the stability of close two planet systems

    CERN Document Server

    Deck, Katherine M; Holman, Matthew J

    2013-01-01

    Motivated by the population of multi-planet systems with orbital period ratios 1first order mean motion resonance can be reduced to a one degree of freedom problem (Sessin & Ferraz Mello (1984), Wisdom (1986), Henrard et al. (1986)). Using this analytically tractable Hamiltonian, we apply the resonance overlap criterion to predict the onset of large scale chaotic motion in close two planet systems. The reduced Hamiltonian has only a weak dependence on the planetary mass ratio, and hence the overlap criterion is independent of the planetary mass ratio at lowest order. Numerical integrations confirm that the planetary mass ratio has little effect on the structure of the chaotic phase space for close orbits in the low eccentricity (e <~0.1) regime. We show numerically that orbits in the chaotic web produced primarily by first order reso...

  18. Translating landfill methane generation parameters among first-order decay models.

    Science.gov (United States)

    Krause, Max J; Chickering, Giles W; Townsend, Timothy G

    2016-11-01

    Landfill gas (LFG) generation is predicted by a first-order decay (FOD) equation that incorporates two parameters: a methane generation potential (L0) and a methane generation rate (k). Because non-hazardous waste landfills may accept many types of waste streams, multiphase models have been developed in an attempt to more accurately predict methane generation from heterogeneous waste streams. The ability of a single-phase FOD model to predict methane generation using weighted-average methane generation parameters and tonnages translated from multiphase models was assessed in two exercises. In the first exercise, waste composition from four Danish landfills represented by low-biodegradable waste streams was modeled in the Afvalzorg Multiphase Model and methane generation was compared to the single-phase Intergovernmental Panel on Climate Change (IPCC) Waste Model and LandGEM. In the second exercise, waste composition represented by IPCC waste components was modeled in the multiphase IPCC and compared to single-phase LandGEM and Australia's Solid Waste Calculator (SWC). In both cases, weight-averaging of methane generation parameters from waste composition data in single-phase models was effective in predicting cumulative methane generation from -7% to +6% of the multiphase models. The results underscore the understanding that multiphase models will not necessarily improve LFG generation prediction because the uncertainty of the method rests largely within the input parameters. A unique method of calculating the methane generation rate constant by mass of anaerobically degradable carbon was presented (kc) and compared to existing methods, providing a better fit in 3 of 8 scenarios. Generally, single phase models with weighted-average inputs can accurately predict methane generation from multiple waste streams with varied characteristics; weighted averages should therefore be used instead of regional default values when comparing models. Translating multiphase first-order

  19. Magnetic relaxation dynamics driven by the first-order character of magnetocaloric La(Fe,Mn,Si)13.

    Science.gov (United States)

    Lovell, Edmund; Bratko, Milan; Caplin, A David; Barcza, Alexander; Katter, Matthias; Ghivelder, Luis; Cohen, Lesley F

    2016-08-13

    Here, we study the temporal evolution of the magnetic field-driven paramagnetic to ferromagnetic transition in the La(Fe,Mn,Si)13 material family. Three compositions are chosen that show varying strengths of the first-order character of the transition, as determined by the relative magnitude of their magnetic hysteresis and temperature separation between the zero-field transition temperature Tc and the temperature Tcrit, where the transition becomes continuous. Systematic variations in the fixed field, isothermal rate of relaxation are observed as a function of temperature and as a function of the degree of first-order character. The relaxation rate is reduced in more weakly first-order compositions and is also reduced as the temperature is increased towards Tcrit At temperatures above Tcrit, the metastability of the transition vanishes along with its associated temporal dynamics.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.

  20. Disturbance attenuation over a first-order moving average Gaussian noise channel

    Science.gov (United States)

    Xu, Guang-Hui; He, Ding-Xin; Guan, Zhi-Hong; Zhang, Ding-Xue; Zhang, Xian-He

    2015-12-01

    In this paper, the problem of disturbance attenuation has been studied for a linear time-invariant feedback control system with a first-order moving average Gaussian noise channel. By applying the concept of entropy power, a lower bound of signal-to-noise ratio has been achieved which is necessary for stabilisation of a system with the limited channel input power constraint. Moreover, the problem of minimising the influence of a stochastic disturbance on the output has also been investigated, and the controller design method has been obtained by using Youla parameterisation and H2 theory. It is shown that the minimum variance of the system output depends not only on the disturbance variance, noise variance and unstable poles, but also on the non-minimum phase zeros and channel parameter. Finally, the effectiveness of the proposed results is illustrated by a numerical example.

  1. Actions, topological terms and boundaries in first order gravity: A review

    CERN Document Server

    Corichi, Alejandro; Vukasinac, Tatjana

    2016-01-01

    In this review we consider first order gravity in four dimensions. In particular, we focus our attention in formulations where the fundamental variables are a tetrad $e_a^I$ and a SO(3,1) connection ${\\omega_{aI}}^J$. We study the most general action principle compatible with diffeomorphism invariance. This implies, in particular, considering besides the standard Einstein-Hilbert-Palatini term, other terms that either do not change the equations of motion, or are topological in nature. Having a well defined action principle sometimes involves the need for additional boundary terms, whose detailed form may depend on the particular boundary conditions at hand. In this work, we consider spacetimes that include a boundary at infinity, satisfying asymptotically flat boundary conditions and/or an internal boundary satisfying isolated horizons boundary conditions. We focus on the covariant Hamiltonian formalism where the phase space $\\Gamma$ is given by solutions to the equations of motion. For each of the possible ...

  2. The Canonical Structure of the First-Order Einstein-Hilbert Action

    Science.gov (United States)

    McKeon, D. G. C.

    The Dirac constraint formalism is used to analyze the first-order form of the Einstein-Hilbert action in d > 2 dimensions. Unlike previous treatments, this is done without eliminating fields at the outset by solving equations of motion that are independent of time derivatives when they correspond to first class constraints. As anticipated by the way in which the affine connection transforms under a diffeomorphism, not only primary and secondary but also tertiary first class constraints arise. These leave d(d-3) degrees of freedom in phase space. The gauge invariance of the action is discussed, with special attention being paid to the gauge generators of Henneaux, Teitelboim and Zanelli and of Castellani.

  3. The Canonical Structure of the First Order Einstein-Hilbert Action

    CERN Document Server

    McKeon, D G C

    2010-01-01

    The Dirac constraint formalism is used to analyze the first order form of the Einstein-Hilbert action in d > 2 dimensions. Unlike previous treatments, this is done without eliminating fields at the outset by solving equations of motion that are independent of time derivatives when they correspond to first class constraints. As anticipated by the way in which the affine connection transforms under a diffeomorphism, not only primary and secondary but also tertiary first class constraints arise. These leave d(d - 3) degrees of freedom in phase space. The gauge invariance of the action is discussed, with special attention being paid to the gauge generators of Henneaux, Teitelboim and Zanelli and of Castellani.

  4. Collective influence maximization in threshold models of information cascading with first-order transitions

    CERN Document Server

    Pei, Sen; Shaman, Jeffrey; Morone, Flaviano; Makse, Hernán A

    2016-01-01

    In spreading dynamics in social networks, there exists an optimal set of influencers whose activation can induce a global-scale cascade of information. To find the optimal, or minimal, set of spreaders, a method based on collective influence theory has been proposed for spreading dynamics with a continuous phase transition that can be mapped to optimal percolation. However, when it comes to diffusion processes exhibiting a first-order, or discontinuous transition, identifying the set of optimal spreaders with a linear algorithm for large-scale networks still remains a challenging task. Here we address this issue by exploring the collective influence in general threshold models of opinion cascading. Our analysis reveals that the importance of spreaders is fixed by the subcritical paths along which cascades propagate: the number of subcritical paths attached to each spreader determines its contribution to global cascades. The concept of subcritical path allows us to introduce a linearly scalable algorithm for m...

  5. Thermodynamics of rotating black branes in gravity with first order string corrections

    Directory of Open Access Journals (Sweden)

    M. H. Dehghani

    2005-09-01

    Full Text Available   In this paper, the rotating black brane solutions with zero curvature horizon of classical gravity with first order string corrections are introduced. Although these solutions are not asymptotically anti de Sitter, one can use the counterterm method in order to compute the conserved quantities of these solutions. Here, by reviewing the counterterm method for asymptotically anti de Sitter spacetimes, the conserved quantities of these rotating solutions are computed. Also a Smarr-type formula for the mass as a function of the entropy and the angular momenta is obtained, and it is shown that the conserved and thermodynamic quantities satisfy the first law of thermodynamics. Finally, a stability analysis in the canonical ensemble is performed, and it is shown that the system is thermally stable. This is in commensurable with the fact that there is no Hawking-Page phase transition for black object with zero curvature horizon.

  6. First-order coil-globule transition driven by vibrational entropy.

    Science.gov (United States)

    Maffi, Carlo; Baiesi, Marco; Casetti, Lapo; Piazza, Francesco; De Los Rios, Paolo

    2012-01-01

    By shifting the balance between conformational entropy and internal energy, polymers modify their shape under external stimuli, such as changes in temperature. Prominent among such transformations is the coil-globule transition, whereby a polymer can switch from an entropy-dominated coil conformation to a globular one, governed by energy. The nature of the coil-globule transition has remained elusive, with evidence for both continuous and discontinuous transitions, with the two-state behaviour of proteins as an instance of the latter. Theoretical models mostly predict second-order transitions. Here we introduce a model that takes into consideration hitherto neglected features common to any polymer. We show that a first-order phase transition smoothly appears as a function of the model parameters. Our results can relieve part of the conflicts between theory and experiments in the field of protein folding, in the wake of recent studies tracing back the remarkable properties of proteins to basic polymer physics.

  7. A boundary field induced first-order transition in the 2D Ising model: numerical study

    Energy Technology Data Exchange (ETDEWEB)

    Bittner, Elmar; Janke, Wolfhard [Institut fuer Theoretische Physik and Centre for Theoretical Sciences (NTZ), Universitaet Leipzig, Postfach 100 920, D-04009 Leipzig (Germany)], E-mail: elmar.bittner@itp.uni-leipzig.de, E-mail: Wolfhard.janke@itp.uni-leipzig.de

    2008-10-03

    In a recent paper, Clusel and Fortin (2006 J. Phys. A: Math. Gen. 39 995) presented an analytical study of a first-order transition induced by an inhomogeneous boundary magnetic field in the two-dimensional Ising model. They identified the transition that separates the regime where the interface is localized near the boundary from that where it propagates inside the bulk. Inspired by these results, we measured the interface tension by using multimagnetic simulations combined with parallel tempering to determine the phase transition and the location of the interface. Our results are in very good agreement with the theoretical predictions. Furthermore, we studied the spin-spin correlation function for which no analytical results are available.

  8. Illuminating new electroweak states at hadron colliders

    Science.gov (United States)

    Ismail, Ahmed; Izaguirre, Eder; Shuve, Brian

    2016-07-01

    In this paper, we propose a novel powerful strategy to perform searches for new electroweak states. Uncolored electroweak states appear in generic extensions of the Standard Model (SM) and yet are challenging to discover at hadron colliders. This problem is particularly acute when the lightest state in the electroweak multiplet is neutral and all multiplet components are approximately degenerate. In this scenario, production of the charged fields of the multiplet is followed by decay into nearly invisible states; if this decay occurs promptly, the only way to infer the presence of the reaction is through its missing energy signature. Our proposal relies on emission of photon radiation from the new charged states as a means of discriminating the signal from SM backgrounds. We demonstrate its broad applicability by studying two examples: a pure Higgsino doublet and an electroweak quintuplet field.

  9. Illuminating New Electroweak States at Hadron Colliders

    CERN Document Server

    Ismail, Ahmed; Shuve, Brian

    2016-01-01

    In this paper, we propose a novel powerful strategy to perform searches for new electroweak states. Uncolored electroweak states appear in generic extensions of the Standard Model (SM) and yet are challenging to discover at hadron colliders. This problem is particularly acute when the lightest state in the electroweak multiplet is neutral and all multiplet components are approximately degenerate. In this scenario, production of the charged fields of the multiplet is followed by decay into nearly invisible states; if this decay occurs promptly, the only way to infer the presence of the reaction is through its missing energy signature. Our proposal relies on emission of photon radiation from the new charged states as a means of discriminating the signal from SM backgrounds. We demonstrate its broad applicability by studying two examples: a pure Higgsino doublet and an electroweak quintuplet field.

  10. Electroweak tests of the Standard Model

    CERN Document Server

    Erler, Jens

    2012-01-01

    Electroweak precision tests of the Standard Model of the fundamental interactions are reviewed ranging from the lowest to the highest energy experiments. Results from global fits are presented with particular emphasis on the extraction of fundamental parameters such as the Fermi constant, the strong coupling constant, the electroweak mixing angle, and the mass of the Higgs boson. Constraints on physics beyond the Standard Model are also discussed.

  11. Tests of the Electroweak Standard Model

    CERN Document Server

    Erler, Jens

    2012-01-01

    Electroweak precision tests of the Standard Model of the fundamental interactions are reviewed ranging from the lowest to the highest energy experiments. Results from global fits are presented with particular emphasis on the extraction of fundamental parameters such as the Fermi constant, the strong coupling constant, the electroweak mixing angle, and the mass of the Higgs boson. Constraints on physics beyond the Standard Model are also discussed.

  12. An electroweak enigma: Hyperon radiative decays

    Energy Technology Data Exchange (ETDEWEB)

    Vorobyov, A., (spokesperson); /St. Petersburg, INP; Jastrzembski, E.; Lach, J.; Marriner, J.; /Fermilab; Golovtsov, V.; Krivshich, A.; Schegelsky, V.; Smirnov, N.; Terentiev, N.K.; Uvarov, L.; /St. Petersburg, INP; McCliment, E.; Newsom, C.; Norbeck, E.; /Iowa U.; Cooper, P.S.; /Yale U.

    1985-04-03

    The main thrust of this experiment will be to measure the asymmetry parameter for the electroweak decay {Sigma}{sup +} {yields} p{gamma} and verify its branching ratio. As a secondary goal they will measure, or set new upper limits for, the branching ratio of the electroweak decay {Xi}{sup -} {yields} {Sigma}{sup -}{gamma}. Since the {Xi}{sup -} are expected to be polarized, information on the asymmetry parameter may also be available.

  13. Radiative and Electroweak Penguins at Belle

    Science.gov (United States)

    Hyun, HyoJung

    2010-02-01

    Radiative and electroweak penguin decays of B mesons are a sensitive probe of new physics beyond the Standard Model. We study the inclusive and exclusive radiative and electroweak penguin decays of B meson and also search an exotic particle seen by the HyperCP experiment. The measurements are based on a large data sample of 605 fb-1 containing 657 millions BB¯ pairs collected at the Υ(4S) with the Belle detector at the KEKB energy asymmetric e+e- collider.

  14. Electroweak Measurements with Heavy Quarks at SLD

    Energy Technology Data Exchange (ETDEWEB)

    Bellodi, Giulia

    2000-10-03

    The SLD detector collected a sample of 550K hadronic events at the Z{sup 0} peak from e{sup +}e{sup -} collisions at the SLC during the 1993 to 1998 period. Polarized electron beams, a small and stable interaction point and the excellent performance of the 3-D CCD vertex detector provide a unique environment for precision electroweak tests of the Standard Model. Improved measurements of heavy quark electroweak parameters are presented here.

  15. Production of electroweak bosons at colliders

    Indian Academy of Sciences (India)

    Matthias U Mozer

    2012-10-01

    The collider experiments at the Tevatron and LHC are accumulating samples of electroweak bosons of unprecedented size. These huge samples can be used to observe rare processes, such as diboson production which have the potential to show enhancements due to new physics. Alternatively, the great statistical power of the samples allows for detailed studies of electroweak production mechanisms and correspondingly QCD and the proton structure.

  16. Electroweak Kaluza-Klein Dark Matter

    OpenAIRE

    Flacke, Thomas; Kang, Dong Woo; Kong, Kyoungchul; Mohlabeng, Gopolang; Park, Seong Chan

    2017-01-01

    In models with universal extra dimensions (UED), the lightest Kaluza-Klein excitation of neutral electroweak gauge bosons is a stable, weakly interacting massive particle and thus is a candidate for dark matter thanks to Kaluza-Klein parity. We examine concrete model realizations of such dark matter in the context of non-minimal UED extensions. The boundary localized kinetic terms for the electroweak gauge bosons lead to a non-trivial mixing among the first Kaluza-Klein excitations of the ${\\...

  17. 一级相变材料Mn_(1.2)Fe_(0.8)P_(0.4)Si_(0.6)的热磁发电性能%Thermomagnetic power generation performance of first-order phase transition material Mn_(1.2)Fe_(0.8)P_(0.4)Si_(0.6)

    Institute of Scientific and Technical Information of China (English)

    毕力格; 特古斯; 伊日勒图; 石海荣

    2012-01-01

    In this paper,we report on the magnetism and the thermomagnetic power generation performance of a first-order phase transition material Mn_(1.2)Fe_(0.8)P_(0.4)Si_(0.6),which can be used for thermomagnetic power generation that turns heat directly into electricity.The compound is synthesized by using the high-energy ball milling and solid state reaction method.Magnetic measurements show that the compound undergoes a ferromagnetic-to-paramagnetic first-order phase transition at 337 K,accompanied by a giant magnetization change.According to this feature of the material,we design a demonstration device for thermomagnetic power generation,and study the electric current generated by heat induced phase transition.The current increases with the increase of the heat-flow temperature and the mass of material.This study shows that the Mn_(1.2)Fe_(0.8)P_(0.4)Si_(0.6) compound possesses the high performance of thermomagnetic power generation.%本文报道把热能直接转换电能的热磁发电技术所用一级相变新材料Mn_(1.2)Fe_(0.8)P_(0.4)Si_(0.6)的磁性和热磁发电性能.用高能球磨机械合金化技术和固相烧结合成方法制备了Mn_(1.2)Fe_(0.8)P_(0.4)Si_(0.6)化合物.磁性测量结果表明,该化合物呈现从铁磁状态变为顺磁状态的一级相变,居里温度为337 K,并伴随巨大的磁化强度的变化.根据该材料的这一特性,设计制作了热磁发电演示装置,测定了热流引起材料的相变而产生的电流,并研究了固定磁场中热致磁转变产生的电流随热流温度和样品质量的变化.研究结果表明Mn_(1.2)Fe_(0.8)P_(0.4)Si_(0.6)化合物具有很好的热磁发电性能,可作为热磁发电材料.

  18. Fermions on the electroweak string

    CERN Document Server

    Moreno, J M; Quirós, Mariano; Moreno, J M; Oaknin, D H; Quiros, M

    1995-01-01

    We construct a simple class of exact solutions of the electroweak theory including the naked Z--string and fermion fields. It consists in the Z--string configuration (\\phi,Z_\\theta), the {\\it time} and z components of the neutral gauge bosons (Z_{0,3},A_{0,3}) and a fermion condensate (lepton or quark) zero mode. The Z--string is not altered (no feed back from the rest of fields on the Z--string) while fermion condensates are zero modes of the Dirac equation in the presence of the Z--string background (no feed back from the {\\it time} and z components of the neutral gauge bosons on the fermion fields). For the case of the n--vortex Z--string the number of zero modes found for charged leptons and quarks is (according to previous results by Jackiw and Rossi) equal to |n|, while for (massless) neutrinos is |n|-1. The presence of fermion fields in its core make the obtained configuration a superconducting string, but their presence (as well as that of Z_{0,3},A_{0,3}) does not enhance the stability of the Z--stri...

  19. Recent Electroweak Results from ATLAS

    CERN Document Server

    Long, Brian Alexander; The ATLAS collaboration

    2016-01-01

    The inclusive productions of the W and the on- or off-shell Z/gamma* bosons are standard candles at hadron colliders, while the productions of jets in association with a W or a Z boson are important processes to study QCD in multi-scale environments. The measurements of their production cross-sections integrated and differential in several variables have been measured at 7, 8 and 13 TeV centre-of-mass energies and are compared to high-order QCD calculations and Monte Carlo simulations. These measurements have an impact on our knowledge of the parton densities of the proton, test resummation effects and hard emissions for small and large momentum transfers, respectively. The ATLAS collaboration has also carried out a set of measurements that provide stringent tests of the electroweak sector of Standard Model at different centre-of-mass energies from 7 to 13 TeV, specifically on di- and tri-boson production cross sections, vector boson fusion and scattering. These measurements are compared to (N)NLO QCD predict...

  20. Supersymmetry at the electroweak scale

    CERN Document Server

    Chankowski, P H

    1996-01-01

    The simplest interpretation of the global success of the Standard Model is that new physics decouples well above the electroweak scale. Supersymmetric extension of the Standard Model offers the possibility of light chargino and the right-handed stop (with masses below $M_Z$), and still maintaining the successful predictions of the Standard Model. The value of $R_b$ can then be enhanced up to $\\sim 0.218$ (the Standard Model value is $\\sim 0.216$). Light chargino and stop give important contribution to rare processes such as $b\\rightarrow s \\gamma$, $\\overline K^0-K^0$ and $\\overline B^0-B^0$ mixing but consistency with experimental results is maintained in a large region of the parameter space. The exotic four-jet events reported by ALEPH (if confirmed) may constitute a signal for supersymmetry with such a light spectrum and with explicitly broken $R-$parity. Their interpretation as pair production of charginos with $m_C\\sim 60$ GeV, with subsequent decay $C\\rightarrow \\tilde t_R b \\rightarrow dsb$ (where $m_...

  1. Cosmological phase transitions and their properties in the NMSSM

    Science.gov (United States)

    Kozaczuk, Jonathan; Profumo, Stefano; Haskins, Laurel Stephenson; Wainwright, Carroll L.

    2015-01-01

    We study cosmological phase transitions in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) in light of the Higgs discovery. We use an effective field theory approach to calculate the finite temperature effective potential, focusing on regions with significant tree-level contributions to the Higgs mass, a viable neutralino dark matter candidate, 1-2 TeV stops, and with the remaining particle spectrum compatible with current LHC searches and results. The phase transition structure in viable regions of parameter space exhibits a rich phenomenology, potentially giving rise to one- or two-step first-order phase transitions in the singlet and/or SU(2) directions. We compute several parameters pertaining to the bubble wall profile, including the bubble wall width and Δ β (the variation of the ratio in Higgs vacuum expectation values across the wall). These quantities can vary significantly across small regions of parameter space and can be promising for successful electroweak baryogenesis. We estimate the wall velocity microphysically, taking into account the various sources of friction acting on the expanding bubble wall. Ultra-relativistic solutions to the bubble wall equations of motion typically exist when the electroweak phase transition features substantial supercooling. For somewhat weaker transitions, the bubble wall instead tends to be sub-luminal and, in fact, likely sub-sonic, suggesting that successful electroweak baryogenesis may indeed occur in regions of the NMSSM compatible with the Higgs discovery.

  2. High-Density Expansion for the Spinless Fermion Model I:. First Order in 1/z and Horwitz-Callen Renormalization

    Science.gov (United States)

    Bartkowiak, M.; Münger, P.; Micnas, R.

    A diagrammatic technique for Hubbard's operators is employed to perform systematically the high-density expansion for the three-dimensional spinless fermion model. The molecular field theory is obtained by the zero-order renormalization of blocks. Summation of the first order diagrams is carried out in both selfconsistent and correctional way. It turns out that the charge ordering parameter, calculated self-consistently, has a jump for a certain medial temperature. We have also shown, that the Horwitz-Callen renormalization leads to the first or second order phase transition, depending on t/W and fails when this ratio is large enough. The phase diagrams of the system for the half-filled band case, derived in both unrenormalized and renormalized first order of high-density expansion are presented.

  3. Influence of thermal annealing and magnetic field on first order magnetic transition in Pd substituted FeRh

    Energy Technology Data Exchange (ETDEWEB)

    Kushwaha, Pallavi; Lakhani, Archana; Rawat, R; Chaddah, P, E-mail: archnalakhani@csr.ernet.i [UGC-DAE Consortium for Scientific Research University Campus, Khandwa Road Indore-452001, M.P (India)

    2010-01-01

    Influence of successive thermal annealing and magnetic field on First order antiferro (AFM) to ferromagnetic (FM) transition in the Pd substituted FeRh has been studied. With successive thermal annealing CsCl type bcc phase increases at the expense of fct (pseudo fcc) phase. Resistivity measurements do not show any transition in as-cast sample in contrast to annealed samples. AFM to FM transition temperature (T{sub N}) is found to decrease with higher annealing temperature. With the application of magnetic field, T{sub N} shift to lower temperature. These measurements show anomalous thermomagnetic irreversibility besides showing giant magnetoresistance across magnetic field induced first order AFM to FM transition.

  4. Higgs couplings and electroweak observables: a comparison of precision tests

    CERN Document Server

    Barbieri, Riccardo

    2013-01-01

    Is the weak scale natural? This ever pending question makes the search for new particle production a highly motivated primary goal of the next LHC phase. These searches may or may not be successful. While waiting for a needed higher energy collider to extend the direct exploration, the search for signs of new physics might be confined to indirect tests for quite some time. In a few fully calculable models, weakly or semi-strongly interacting, we compare the significance to measure the Higgs couplings versus the electroweak observables.

  5. Generalized ensemble method applied to study systems with strong first order transitions

    Science.gov (United States)

    Małolepsza, E.; Kim, J.; Keyes, T.

    2015-09-01

    At strong first-order phase transitions, the entropy versus energy or, at constant pressure, enthalpy, exhibits convex behavior, and the statistical temperature curve correspondingly exhibits an S-loop or back-bending. In the canonical and isothermal-isobaric ensembles, with temperature as the control variable, the probability density functions become bimodal with peaks localized outside of the S-loop region. Inside, states are unstable, and as a result simulation of equilibrium phase coexistence becomes impossible. To overcome this problem, a method was proposed by Kim, Keyes and Straub [1], where optimally designed generalized ensemble sampling was combined with replica exchange, and denoted generalized replica exchange method (gREM). This new technique uses parametrized effective sampling weights that lead to a unimodal energy distribution, transforming unstable states into stable ones. In the present study, the gREM, originally developed as a Monte Carlo algorithm, was implemented to work with molecular dynamics in an isobaric ensemble and coded into LAMMPS, a highly optimized open source molecular simulation package. The method is illustrated in a study of the very strong solid/liquid transition in water.

  6. First-order-reversal-curve analysis of Pr-Fe-B-based nanocomposites

    Science.gov (United States)

    Cornejo, D. R.; Peixoto, T. R. F.; Reboh, S.; Fichtner, P. F. P.; de Franco, V. C.; Villas-Boas, V.; Missell, F. P.

    2010-04-01

    Ribbons of nominal composition (Pr9.5Fe84.5B6)0.96Cr0.01(TiC)0.03 were produced by arc-melting and melt-spinning the alloys on a Cu wheel. X-ray diffraction reveals two main phases, one based upon α-Fe and the other upon Pr2Fe14B. The ribbons show exchange spring behavior with Hc=12.5 kOe and (BH)max=13.6 MGOe when these two phases are well coupled. Transmission electron microscopy revealed that the coupled behavior is observed when the microstructure consists predominantly of α-Fe grains (diameter ˜100 nm.) surrounded by hard material containing Pr2Fe14B. A first-order-reversal-curve (FORC) analysis was performed for both a well-coupled sample and a partially-coupled sample. The FORC diagrams show two strong peaks for both the partially-coupled sample and for the well-coupled material. In both cases, the localization of the FORC probability suggests demagnetizing interactions between particles. Switching field distributions were calculated and are consistent with the sample microstructure.

  7. On new solutions of linear system of first -order fuzzy differential equations with fuzzy coefficient

    Directory of Open Access Journals (Sweden)

    A. Karimi Dizicheh

    2016-03-01

    Full Text Available In this paper, we firstly introduce system of first order fuzzy differential equations. Then, we convert the problem to two crisp systems of first order differential equations. For numerical aspects, we apply exponentially fitted Runge Kutta method to solve the fuzzy problems. We solve some well-known examples in order to demonstrate the applicability and accuracy of results.

  8. POSITIVE SOLUTIONS TO SYSTEMS OF SECOND ORDER NONLOCAL BOUNDARY VALUE PROBLEMS WITH FIRST ORDER DERIVATIVES

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper investigates the existence of positive solutions to systems of second order nonlocal boundary value problems with first order derivatives, in which the nonlinear term is not required to be continuous and involves first order derivatives. The main tool used in this paper is a fixed point index theory in a cone.

  9. Theory Summary of the Electroweak Session for Moriond 2005

    CERN Document Server

    Peccei, Roberto D

    2005-01-01

    I broadly summarize the theoretical contributions in the Electroweak session of the 2005 Moriond meeting under four rubrics: i) neutrinos; ii) cosmology; iii) electroweak interactions; and iv) flavor physics.

  10. Polarization induced water molecule dissociation below the first-order electronic-phase transition temperature

    CERN Document Server

    Arulsamy, Andrew Das; Elersic, Kristina; Modic, Martina; Subramani, Uma Shankar

    2011-01-01

    Hydrogen produced from the photocatalytic splitting of water is one of the reliable alternatives to replace the polluting fossil and the radioactive nuclear fuels. Here, we provide unequivocal evidence for the existence of blue- and red-shifting O$-$H covalent bonds within a single water molecule adsorbed on MgO surface as a result of asymmetric displacement polarizabilities. The adsorbed H-O-H on MgO gives rise to one weaker H-O bond, while the other O-H covalent bond from the same adsorbed water molecule compensates this effect with a stronger bond. The weaker bond (nearest to the surface), the interlayer tunneling electrons and the silver substrate are shown to be the causes for the smallest dissociative activation energy on MgO monolayer. The origin that is responsible to initiate the splitting mechanism is proven to be due to the changes in the polarizability of an adsorbed water molecule, which are further supported by the temperature-dependent static dielectric constant measurements for water below the...

  11. Spatially resolved modelling of inhomogeneous materials with a first order magnetic phase transition

    Science.gov (United States)

    Nielsen, K. K.; Bahl, C. R. H.; Smith, A.; Bjørk, R.

    2017-10-01

    We present a numerical model that can simulate a magnetocaloric sample on the grain size level, including magnetostatics, heat transfer, local hysteresis and spatial variation of stoichiometry expressed as a variation in Curie temperature, \

  12. Full correspondence between asymmetric filling of slits and first-order phase transition lines

    OpenAIRE

    Leszek Szybisz; Sartarelli, Salvador A.

    2011-01-01

    Adsorption on single planar walls and filling of slits with identical planar walls are investigated in the frame of the density functional theory. In this sort of slits the external potential is symmetric with respect to its central plane. Calculations were carried out by applying both the canonical and grand canonical ensembles (CE and GCE, respectively). The behavior is analyzed by varying the strength of the adsorbate-substrate attraction, the temperature T, and the coverage Γℓ. Results ob...

  13. Naturalness of electroweak physics within minimal supergravity

    CERN Document Server

    Cassel, S

    2011-01-01

    Low energy supersymmetry is motivated by its use as a solution to the hierarchy problem of the electroweak scale. Having motivated this model with naturalness arguments, it is then necessary to check whether the experimentally allowed parameter space permits realisations of the model with low fine tuning. The scope of this thesis is a study of naturalness of the electroweak physics in the minimal supergravity model. The latest experimental constraints are applied, and the fine tuning is quantitatively evaluated for a scan across the parameter space. The fine tuning of the electroweak scale is evaluated at 2-loop order, and the fine tuning of the neutralino dark matter thermal relic energy density is also determined. The natural regions of the parameter space are identified and the associated phenomenology relevant for detection discussed. Naturalness limits are also found for the parameter space and spectrum. The minimum fine tuning found is 1 part in 9 when dark matter constraints are neglected, and 1 part i...

  14. New Electroweak Model Without a Higgs Particle

    Institute of Scientific and Technical Information of China (English)

    WUNing

    2002-01-01

    A new unified electroweak model is proposed in this paper,In this unified electroweak model,Higgs echanism is not used.So no Higgs particle exists in the model.In order to keep the masses of intermediate gauge bosons non-zero,two sets of gauge fields will be introduced.In order to introduce symmetry breaking and to help to introduce the masses of all fileds.a vacuum potential is needed.Except for those terms concerning Higgs particle,the fundamental dynamical properties of this model are similar to those of the standard model.And in a proper limit,this model with approximately return to the standard model.The purpose of this paper is not to say that the Higgs particle does not exist in Nature,it is only to prove that,without a Higgs particle,we can also set up a unified electroweak model which is consistent with present experiments.

  15. Workshop on electroweak symmetry breaking: proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Hinchliffe, I. (ed.)

    1984-10-01

    A theoretical workshop on electroweak symmetry breaking at the Superconducting Supercollider was held at Lawrence Berkeley Laboratory, June 4-22, 1984. The purpose of the workshop was to focus theoretical attention on the ways in which experimentation at the SSC could reveal manifestations of the phenomenon responsible for electroweak symmetry breaking. This issue represents, at present, the most compelling scientific argument for the need to explore the energy region to be made accessible by the SSC, and a major aim of the workshop was to involve a broad cross section of particle theorists in the ongoing process of sharpening the requirements for both accelerator and detector design that will ensure detection and identification of meaningful signals, whatever form the electroweak symmetry breaking phenomenon should actually take. Separate entries were prepared for the data base for the papers presented.

  16. Automation of electroweak corrections for LHC processes

    Science.gov (United States)

    Chiesa, Mauro; Greiner, Nicolas; Tramontano, Francesco

    2016-01-01

    Next-to-leading order (NLO) electroweak corrections will play an important role in Run 2 of the Large Hadron Collider (LHC). Even though they are typically moderate at the level of total cross sections, they can lead to substantial deviations in the shapes of distributions. In particular, for the search for new physics, but also for a precise determination of Standard Model observables, their inclusion in theoretical predictions is mandatory for a reliable estimation of the Standard Model contribution. In this article we review the status and recent developments in electroweak calculations and their automation for LHC processes. We discuss general issues and properties of NLO electroweak corrections and present some examples, including the full calculation of the NLO corrections to the production of a W-boson in association with two jets computed using GoSam interfaced to MadDipole.

  17. The electroweak polarization asymmetry: A guided tour

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, D.C.

    1988-10-01

    A comprehensive review is provided of the electroweak polarization asymmetry at the Z/sup 0/, a highly accurate measure of the Z/sup 0/ coupling to fermions. Its significance as a precision test of the Standard Model is explored in detail. Emphasized are the role of electroweak symmetry-breaking and radiative corrections; the non-decoupling of new physics beyond the Z/sup 0/; and the testing of extensions of the Standard Model, such as supersymmetry, technicolor, new generations of fermions, grand unification, and new gauge forces. Also discussed are the relationship of the polarization asymmetry to other electroweak observables and its superiority to other Z/sup 0/ asymmetries. Experimental issues are briefly presented, stressing the importance of polarization at the SLC and LEP e/sup +/e/sup -/ colliders. 42 refs., 13 figs., 2 tabs.

  18. Chirally symmetric strong and electroweak interactions

    Science.gov (United States)

    Rajpoot, Subhash

    1988-07-01

    Strong and electroweak interactions may be a relic of the spontaneous breakdown of a chirally symmetric colour-flavour gauge group. The minimum possibility of such a structure that is symmetric between left and right is SU(3) L×SU(3) R×SU(2) L×SU(2) R×U(1) B- L where quantum chromodynamics originates in the chiral colour group SU(3) L×SU(3) R and the electroweak interaction originates in the ambidextrous electroweak interaction group SU L×SU(2) R×U(1) B- L. The chiral anomalies are cancelled by adding a set of fermions that transform as singlets under the weak interaction group SU(2) L×SU(2) R. This model requires only three Higgs representations to break the proposed gauge symmetry to SU(3) C×U(1) em and give masses to all the quarks and leptons of the theory. All fermion masses are “see-saw” masses.

  19. A first-order Lyapunov robustness method for linear systems with uncertain parameters

    Science.gov (United States)

    Leal, M. A.; Gibson, J. S.

    1990-01-01

    A method for stability-robustness analysis based on a quadratic Liapunov function that varies linearly with uncertainty parameters is derived. Linear time-invariant systems with structured uncertainties are discussed. The Liapunov function is optimized numerically to maximize the robustness region in parameter space. Numerical results are given for four examples in which the first-order method is compared to previous Liapunov methods. While the zero-order method is slightly better than the first-order method for one example, the first-order method is clearly superior in the other three (more realistic) examples. The first-order method is especially superior for the active control of flexible structures, where robustness with respect to (1) unmodeled coupling between modeled modes and (2) unmodeled modes is important. For such applications, the first-order method is much better at detecting the increased robustness associated with increased separation between frequencies.

  20. A first-order Lyapunov robustness method for linear systems with uncertain parameters

    Science.gov (United States)

    Leal, M. A.; Gibson, J. S.

    1990-01-01

    A method for stability-robustness analysis based on a quadratic Liapunov function that varies linearly with uncertainty parameters is derived. Linear time-invariant systems with structured uncertainties are discussed. The Liapunov function is optimized numerically to maximize the robustness region in parameter space. Numerical results are given for four examples in which the first-order method is compared to previous Liapunov methods. While the zero-order method is slightly better than the first-order method for one example, the first-order method is clearly superior in the other three (more realistic) examples. The first-order method is especially superior for the active control of flexible structures, where robustness with respect to (1) unmodeled coupling between modeled modes and (2) unmodeled modes is important. For such applications, the first-order method is much better at detecting the increased robustness associated with increased separation between frequencies.

  1. Study of the first-order transition in the spin-1 Blume–Capel model by using effective-field theory

    Energy Technology Data Exchange (ETDEWEB)

    Costabile, Emanuel [Departamento de Física, Universidade Federal do Amazonas, 3000, Japiim, 69077-000, Manaus, AM (Brazil); Amazonas, Marcio A. [Departamento de Física, Universidade Federal do Amazonas, 3000, Japiim, 69077-000, Manaus, AM (Brazil); Instituto Federal de Educação, Ciência e Tecnologia do Amazonas, 1975, Sete de Setembro, 69020-120, Manaus, AM (Brazil); Viana, J. Roberto [Departamento de Física, Universidade Federal do Amazonas, 3000, Japiim, 69077-000, Manaus, AM (Brazil); Sousa, J. Ricardo de, E-mail: jsousa@ufam.edu.br.br [Departamento de Física, Universidade Federal do Amazonas, 3000, Japiim, 69077-000, Manaus, AM (Brazil); National Institute of Science and Technology for Complex Systems, Universidade Federal do Amazonas, 3000, Japiim, 69077-000, Manaus, AM (Brazil)

    2012-10-01

    The spin-1 Blume–Capel model on a square lattice is studied by using an effective-field theory (EFT) with correlation. We propose an expression for the free energy within the EFT. The phase diagram is constructed in the temperature (T) and single-ion anisotropy amplitude (D) plane. The first-order transition line is obtained by Maxwell construction (comparison between free energies). Our results predict first-order transitions at low temperatures and large anisotropy strengths, which correspond in the phase diagram to the existence of a tricritical point (TCP). We compare our results with mean-field approximation (MFA), that show a qualitative correct behavior for the phase diagram. -- Highlights: ► In this Letter we have studied the spin-1 Blume–Capel model by using effective-field theory (EFT). ► The first-order line is obtained for the first time. ► The model presents second and first-order phase transitions. ► We propose a functional to treat the first-order line. ► We discuss other alternative by using EFT to study first-order line.

  2. Magnetic monopoles and vortices in the standard model of electroweak interactions

    CERN Document Server

    Achúcarro, A

    2000-01-01

    These lectures start with an elementary introduction to the subject of magnetic monopoles which should be accesible from any physics background. In the Weinberg-Salam model of electroweak interactions, magnetic monopoles appear at the ends of a type of non-topological vortices called electroweak strings. These will also be discussed, as well as recent simulations of their formation during a phase transition which indicate that, in the (unphysical) range of parameters in which the strings are classically stable, they can form with a density comparable to topological vortices.

  3. Precision electroweak tests of the Standard Model

    Energy Technology Data Exchange (ETDEWEB)

    Renton, Peter B. [Denys Wilkinson Building, Oxford (United Kingdom)]. E-mail: p.renton1@physics.ox.ac.uk

    2002-09-01

    The present status of precision electroweak data is reviewed. These data include measurements of e{sup +}e{sup -}{yields}f-barf, taken at the Z resonance at LEP, which are used to determine the mass and width of the Z-boson. In addition, measurements have also been made of the forward-backward asymmetries for leptons and heavy-quarks, and also the final state polarization of the {tau}-lepton. At SLAC, where the electron beam was polarized, measurements were made of the left-right polarized asymmetry, A{sub LR}, and the left-right forward-backward asymmetries for b- and c-quarks. The mass, m{sub W}, and width, {gamma}{sub W}, of the W-boson have been measured at the Tevatron and at LEP, and the mass of the top-quark, m{sub t}, has been measured at the Tevatron. These data, plus other electroweak data, are used in global electroweak fits in which various Standard Model (SM) parameters are determined. A comparison is made between the results of the direct measurements of m{sub W} and m{sub t} with the indirect results coming from electroweak radiative corrections. Using all precision electroweak data, fits are also made to determine limits on the mass of the Higgs boson, m{sub H}. The influence on these limits of specific measurements, particularly those which are somewhat inconsistent with the SM, is explored. The data are also analysed in terms of the quasi-model-independent {epsilon} variables. Finally, the impact on the electroweak fits of the improvements in the determination of the W-boson and top-quark masses, expected from the Tevatron Run 2, is examined. (author)

  4. Quadratic electroweak corrections for polarized Moller scattering

    Energy Technology Data Exchange (ETDEWEB)

    A. Aleksejevs, S. Barkanova, Y. Kolomensky, E. Kuraev, V. Zykunov

    2012-01-01

    The paper discusses the two-loop (NNLO) electroweak radiative corrections to the parity violating electron-electron scattering asymmetry induced by squaring one-loop diagrams. The calculations are relevant for the ultra-precise 11 GeV MOLLER experiment planned at Jefferson Laboratory and experiments at high-energy future electron colliders. The imaginary parts of the amplitudes are taken into consideration consistently in both the infrared-finite and divergent terms. The size of the obtained partial correction is significant, which indicates a need for a complete study of the two-loop electroweak radiative corrections in order to meet the precision goals of future experiments.

  5. Top and electroweak measurements at the Tevatron

    Science.gov (United States)

    Bartoš, P.; CDF Collaboration; D0 Collaboration

    2017-07-01

    In this report, we summarize the latest results of the top-quark mass and electroweak measurements from the Tevatron. Since the world combination of top-quark mass measurements was done, CDF and D0 experiments improved the precision of several results. Some of them reach the relative precision below 1% for a single measurement. From the electroweak results, we report on the WW and WZ production cross-section, measurements of the weak mixing angle and indirect measurements of W boson mass. The Tevatron results of the weak mixing angle are still the most precise ones of hadron colliders.

  6. Recent results on Electroweak measurements from ATLAS

    Directory of Open Access Journals (Sweden)

    Benekos Nektarios Chr.

    2015-01-01

    Full Text Available ATLAS measurements of multiboson production processes involving combinations of W,Z and isolated photons are summarized. Measurements using data at 7 TeV and at 8 TeV are presented. The measurements are performed using leptonic decay modes, including the invisible decay Z → v v̅, as well as semileptonic channels. Measurements of single and diboson production in association with two forward jets is sensitive to electroweak vector boson fusion and scattering processes. An observation of the electroweak production of the Z boson and an evidence of same sign WW production are reported.

  7. Top and Electroweak Measurements at the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Bartos, P. [Comenius U.

    2016-01-01

    In this report, we summarize the latest results of the top-quark mass and electroweak measurements from the Tevatron. Since the world combination of top-quark mass measurements was done, CDF and D0 experiments improved the precision of several results. Some of them reach the relative precition below 1% for a single measurement. From the electroweak results, we report on the WW and WZ production cross section, measurements of the weak mixing angle and indirect measurements of W boson mass. The Tevatron results of the weak mixing angle are still the most precise ones of hadron colliders.

  8. The standard model of electroweak interactions

    CERN Document Server

    Pich, Antonio

    1994-01-01

    What follows is an updated version of the lectures given at the CERN Academic Training (November 1993) and at the Jaca Winter Meeting (February 1994). The aim is to provide a pedagogical introduction to the Standard Model of electroweak interactions. After briefly reviewing the empirical considerations which lead to the construction of the Standard Model Lagrangian, the particle content, structure and symmetries of the theory are discussed. Special emphasis is given to the many phenomenological tests (universality, flavour-changing neutral currents, precision measurements, quark mixing, etc.) which have established this theoretical framework as the Standard Theory of electroweak interactions.

  9. The unified equation for the evaluation of degenerated first-order reactions in dynamic electrophoresis.

    Science.gov (United States)

    Trapp, Oliver

    2006-08-01

    An analytical solution for the unified equation for degenerated (pseudo-) first-order reactions, e.g., enantiomerization processes, in dynamic CE is presented, and validated with a dataset of 31 250 elution profiles covering typical experimental parameters. The unified equation was applied to determine the enantiomerization barrier of the hypnotic glutarimide derivative thalidomide (Contergan(R)) by dynamic capillary electrokinetic chromatography (DEKC). The enantiomer separation of thalidomide was performed in an aqueous 50 mM sodium borate buffer at pH 9.3 in the presence of the chiral mobile phase additive carboxymethyl-beta-CD. Interconversion profiles featuring pronounced plateau formation were observed. Activation parameters DeltaH( not equal) and DeltaS( not equal) were obtained from temperature-dependent measurements between 20.0 and 37.5 degrees C in 2.5K steps. From the activation parameters the enantiomerization barrier of thalidomide at 37 degrees C under basic conditions were calculated to be DeltaG( not equal) = 93.2 kJ/mol. Comparison of the kinetic data with results obtained at pH 8.0 reveals the catalytic influence of the base on the enantiomerization barrier.

  10. The gravitational Hamiltonian, first order action, Poincar\\'e charges and surface terms

    CERN Document Server

    Corichi, Alejandro

    2015-01-01

    We consider the issue of attaining a consistent Hamiltonian formulation, after a 3+1 splitting, of a well-defined action principle for asymptotically flat gravity. More precisely, our starting point is the gravitational first order Holst action with surface terms and fall-off conditions that make the variational principle and the covariant phase space formulation well-defined for asymptotically flat spacetimes. Keeping all surface terms and paying due attention to subtleties that arise from the different cut-offs at infinity, we give a derivation of the gravitational Hamiltonian starting from this action. The 3+1 decomposition and time gauge fixing results in a well-defined Hamiltonian action and a well-defined Hamiltonian formulation for the standard -and more general- asymptotic ADM conditions. Unlike the case of the Einstein-Hilbert action with Gibbons-Hawking-York or Hawking-Horowitz terms, here we {\\it {do}} recover the ADM energy-momentum from the covariant surface term also when more general variations...

  11. Probing the A1 to L10 transformation in FeCuPt using the first order reversal curve method

    Directory of Open Access Journals (Sweden)

    Dustin A. Gilbert

    2014-08-01

    Full Text Available The A1-L10 phase transformation has been investigated in (001 FeCuPt thin films prepared by atomic-scale multilayer sputtering and rapid thermal annealing (RTA. Traditional x-ray diffraction is not always applicable in generating a true order parameter, due to non-ideal crystallinity of the A1 phase. Using the first-order reversal curve (FORC method, the A1 and L10 phases are deconvoluted into two distinct features in the FORC distribution, whose relative intensities change with the RTA temperature. The L10 ordering takes place via a nucleation-and-growth mode. A magnetization-based phase fraction is extracted, providing a quantitative measure of the L10 phase homogeneity.

  12. Non-equilibrium statistical field theory for classical particles: Non-linear structure evolution with first-order interaction

    CERN Document Server

    Bartelmann, Matthias; Berg, Daniel; Kozlikin, Elena; Lilow, Robert; Viermann, Celia

    2014-01-01

    We calculate the power spectrum of density fluctuations in the statistical non-equilibrium field theory for classical, microscopic degrees of freedom to first order in the interaction potential. We specialise our result to cosmology by choosing appropriate initial conditions and propagators and show that the non-linear growth of the density power spectrum found in numerical simulations of cosmic structure evolution is reproduced well to redshift zero and for arbitrary wave numbers. The main difference of our approach to ordinary cosmological perturbation theory is that we do not perturb a dynamical equation for the density contrast. Rather, we transport the initial phase-space distribution of a canonical particle ensemble forward in time and extract any collective information from it at the time needed. Since even small perturbations of particle trajectories can lead to large fluctuations in density, our approach allows to reach high density contrast already at first order in the perturbations of the particle...

  13. Nonlinear first order PDEs reducible to autonomous form polynomially homogeneous in the derivatives

    Science.gov (United States)

    Gorgone, Matteo; Oliveri, Francesco

    2017-03-01

    It is proved a theorem providing necessary and sufficient conditions enabling one to map a nonlinear system of first order partial differential equations, polynomial in the derivatives, to an equivalent autonomous first order system polynomially homogeneous in the derivatives. The result is intimately related to the symmetry properties of the source system, and the proof, involving the use of the canonical variables associated to the admitted Lie point symmetries, is constructive. First order Monge-Ampère systems, either with constant coefficients or with coefficients depending on the field variables, where the theorem can be successfully applied, are considered.

  14. Electroweak Chiral Lagrangian for Neutral Higgs Boson

    Institute of Scientific and Technical Information of China (English)

    WANG Shun-Zhi; WANG Qing

    2008-01-01

    A neutral Higgs boson is added into the traditional electroweak chiral Lagrangian by writing down all possible high dimension operators. The matter part of the Lagrangian is investigated in detail. We find that if Higgs field dependence of Yukawa couplings can be factorized out, there will be no flavour changing neutral couplings; neutral Higgs can induce coupling between light and heavy neutrinos.

  15. Recent Electroweak Results from the LHC

    CERN Document Server

    Helary, Louis; The ATLAS collaboration

    2016-01-01

    Slides for conference Aspen 2016. The talk is about recent Electroweak results at the LHC. It is focused on multi-boson physics and boson EWK production. It is supposed to summarize results from ATLAS, CMS and LHCb, but given the topic it contains only material from ATLAS and CMS.

  16. Electroweak Physics in the Forward Region

    CERN Multimedia

    Sirendi, Marek

    2015-01-01

    LHCb has an active electroweak physics programme with measurements of inclusive processes such as Z and W production in leptonic final states already published. The EW working group is also branching into jet physics with completed Z+jet and Z+b-jet analyses. Recent results in this field are presented.

  17. Electroweak Kaluza-Klein Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Flacke, Thomas [IBS, Daejeon; Kang, Dong Woo [Sungkyunkwan U.; Kong, Kyoungchul [Pittsburgh U.; Mohlabeng, Gopolang [U. Kansas, Lawrence; Park, Seong Chan [Korea Inst. Advanced Study, Seoul

    2017-02-09

    In models with universal extra dimensions (UED), the lightest Kaluza-Klein excitation of neutral electroweak gauge bosons is a stable, weakly interacting massive particle and thus is a candidate for dark matter thanks to Kaluza-Klein parity. We examine concrete model realizations of such dark matter in the context of non-minimal UED extensions. The boundary localized kinetic terms for the electroweak gauge bosons lead to a non-trivial mixing among the first Kaluza-Klein excitations of the ${\\rm SU}(2)_W$ and ${\\rm U}(1)_Y$ gauge bosons and the resultant low energy phenomenology is rich. We investigate implications of various experiments including low energy electroweak precision measurements, direct and indirect detection of dark matter particles and direct collider searches at the LHC. Notably, we show that the electroweak Kaluza-Klein dark matter can be as heavy as 2.4 TeV, which is significantly higher than $1.3$ TeV as is indicated as an upper bound in the minimal UED model.

  18. Electroweak Physics Measurements at the LHC

    OpenAIRE

    Besson, N.

    2008-01-01

    Although often quoted as a discovery collider, the LHC will also allow for precise measurements. In particular, in the electroweak sector, the determination of the masses of the top quark and the W boson will benefit from high statistics and new methods.

  19. Electroweak and Top Results from ATLAS

    CERN Document Server

    Marx, M; The ATLAS collaboration

    2013-01-01

    Recent electroweak and top measurements with the ATLAS detector are presented for $sqrt{s}=$ 7 TeV and 8 TeV data. This includes inclusive and differential diboson production cross section measurements, limits on anomalous triple gauge couplings, top production cross section measurements and studies of top properties.

  20. ELECTROWEAK VECTOR BOSON PRODUCTION IN JOINT RESUMMATION.

    Energy Technology Data Exchange (ETDEWEB)

    KULESZA,A.; STERMAN,G.; VOGELSANG,W.

    2002-03-16

    We study the application of the joint resummation to electroweak boson production at hadron colliders. The joint resummation formalism resumes both threshold and transverse momentum corrections to the transverse momentum distribution at, next-to-leading logarithmic accuracy. We obtain a good description of the transverse momentum distribution of Z bosons produced at the Tevatron collider.

  1. Propagators of Generalized Schrödinger Equations Related by First-order Supersymmetry

    Directory of Open Access Journals (Sweden)

    A. Schulze-Halberg

    2011-01-01

    Full Text Available We construct an explicit relation between propagators of generalized Schrödinger equations that are linked by a first-order supersymmetric transformation. Our findings extend and complement recent results on the conventional case [1].

  2. First-order Convex Optimization Methods for Signal and Image Processing

    DEFF Research Database (Denmark)

    Jensen, Tobias Lindstrøm

    2012-01-01

    In this thesis we investigate the use of first-order convex optimization methods applied to problems in signal and image processing. First we make a general introduction to convex optimization, first-order methods and their iteration complexity. Then we look at different techniques, which can...... be used with first-order methods such as smoothing, Lagrange multipliers and proximal gradient methods. We continue by presenting different applications of convex optimization and notable convex formulations with an emphasis on inverse problems and sparse signal processing. We also describe the multiple......-description problem. We finally present the contributions of the thesis. The remaining parts of the thesis consist of five research papers. The first paper addresses non-smooth first-order convex optimization and the trade-off between accuracy and smoothness of the approximating smooth function. The second and third...

  3. Existence and attractivity results for nonlinear first order random differential equations

    Directory of Open Access Journals (Sweden)

    Bapurao C. Dhage

    2010-01-01

    Full Text Available In this paper, the existence and attractivity results are proved for nonlinear first order ordinary random differential equations. Two examples are provided to demonstrate the realization of the abstract developed theory.

  4. Discrete Methods Based on First Order Reversal Curves to Identify Preisach Model of Smart Materials

    Institute of Scientific and Technical Information of China (English)

    LI Fan; ZHAO Jian-hui

    2007-01-01

    Preisach model is widely used in modeling of smart materials. Although first order reversal curves (FORCs) have often found applications in the fields of physics and geology, they are able to serve to identify Preisach model. In order to clarify the relationship between the Preisach model and the first order reversal curves, this paper is directed towards: (1) giving the reason a first order reversal curve is introduced; (2) presenting, for identifying Preisach model, two discrete methods, which are analytically based on first order reversal curves. Herein also is indicated the solution's uniqueness of these two identifying methods. At last, the validity of these two methods is verified by simulating a real smart actuator both methods have been applied to.

  5. Existential Second Order Logic Expression With Horn First Order for Max Clique (Decision Version)

    CERN Document Server

    Manyem, Prabhu

    2010-01-01

    We will show that the maximum clique problem (decision version) can be expressed in existential second order (ESO) logic, where the first order part is a Horn formula in second-order quantified predicates.

  6. Metamaterial-Inspired First-Order Probe for Spherical Near-Field Antenna Measurements

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2011-01-01

    A first-order probe based on a two-element split ring resonator (SRR) array is presented. The probe is applicable at low frequencies due to its small size and excellent mode content.......A first-order probe based on a two-element split ring resonator (SRR) array is presented. The probe is applicable at low frequencies due to its small size and excellent mode content....

  7. A first-order dynamical model of hierarchical triple stars and its application

    CERN Document Server

    Xu, Xingbo; Fu, Yanning

    2015-01-01

    For most hierarchical triple stars, the classical double two-body model of zeroth-order cannot describe the motions of the components under the current observational accuracy. In this paper, Marchal's first-order analytical solution is implemented and a more efficient simplified version is applied to real triple stars. The results show that, for most triple stars, the proposed first-order model is preferable to the zeroth-order model either in fitting observational data or in predicting component positions.

  8. The metatheory of first-order logic: a contribution to a defence of Principia Mathematica

    CERN Document Server

    Boyce, Stephen

    2010-01-01

    This paper presents evidence that Principia Mathematica's account of first-order logic may be superior to currently accepted classical rivals. It is shown firstly that difficulties arise if one attempts to express the metatheory of contemporary first-order logic in a first-order set theory equivalent to NBG set theory since the notion of a domain of interpretation (of the a first-order language) cannot be a class (proper or otherwise). This is a pressing problem, since if the metatheory is left informal it appears that one can define absurd entities in the metatheory - such as the domain D of an interpretation M of a first-order language L that contains a domain E of an interpretation N of L if and only if E is not identical with any individual in E (hence D is identical with some individual in D if and only if it is not). An alternative view of first-order logic, derived from Principia, is then presented. It is shown that Principia avoids the problem just discussed and that a number of widely accepted critic...

  9. Theory of First Order Chemical Kinetics at the Critical Point of Solution.

    Science.gov (United States)

    Baird, James Kern; Lang, Joshua R

    2017-09-27

    Liquid mixtures, which have a phase diagram exhibiting a miscibility gap ending in a critical point of solution, have been used as solvents for chemical reactions. The reaction rate in the forward direction has often been observed to slow down as a function of temperature in the critical region. Theories based upon the Gibbs free energy of reaction as the driving force for chemical change have been invoked to explain this behavior. With the assumption that the reaction is proceeding under relaxation conditions, these theories expand the free energy in a Taylor series about the position of equilibrium. Since the free energy is zero at equilibrium, the leading term in the Taylor series is proportional to the first derivative of the free energy with respect to the extent of reaction. To analyze the critical behavior of this derivative, the theories invoke the principle of critical point isomorphism, which is thought to govern all critical phenomena. They find that the derivative goes to zero in the critical region, which accounts for the slowing down observed in the reaction rate. As has been pointed out, however, most experimental rate investigations have been carried out under irreversible conditions as opposed to relaxation conditions [Shen et al. J. Phys. Chem. A 2015, 119, 8784 - 8791]. Below, we consider a reaction governed by first order kinetics and invoke transition state theory to take into account the irreversible conditions. We express the apparent activation energy in terms of thermodynamic derivatives evaluated under standard conditions as well as the pseudo-equilibrium conditions associated with the reactant and the activated complex. We show that these derivatives approach infinity in the critical region. The apparent activation energy follows this behavior, and its divergence accounts for the slowing down of the reaction rate.

  10. First-order transition in the magnetic vortex matter in superconducting MgB2 tuned by disorder.

    Science.gov (United States)

    Klein, T; Marlaud, R; Marcenat, C; Cercellier, H; Konczykowski, M; van der Beek, C J; Mosser, V; Lee, H S; Lee, S I

    2010-07-23

    The field-driven transition from an ordered Bragg glass to a disordered vortex phase in single-crystalline MgB2 is tuned by an increasing density of point defects, introduced by electron irradiation. The discontinuity observed in magnetization attests to the first-order nature of the transition. The temperature and defect density dependences of the transition field point to vortex pinning mediated by fluctuations in the quasiparticle mean free path, and reveal the mechanism of the transition in the absence of complicating factors such as layeredness or thermal fluctuations.

  11. Macroscopic yielding in jammed solids is accompanied by a nonequilibrium first-order transition in particle trajectories

    Science.gov (United States)

    Kawasaki, Takeshi; Berthier, Ludovic

    2016-08-01

    We use computer simulations to analyze the yielding transition during large-amplitude oscillatory shear of a simple model for soft jammed solids. Simultaneous analysis of global mechanical response and particle-scale motion demonstrates that macroscopic yielding, revealed by a smooth crossover in mechanical properties, is accompanied by a sudden change in the particle dynamics, which evolves from nondiffusive motion to irreversible diffusion as the amplitude of the shear is increased. We provide numerical evidence that this sharp change corresponds to a nonequilibrium first-order dynamic phase transition, thus establishing the existence of a well-defined microscopic dynamic signature of the yielding transition in amorphous materials in oscillatory shear.

  12. Improved first-order uncertainty method for water-quality modeling

    Science.gov (United States)

    Melching, C.S.; Anmangandla, S.

    1992-01-01

    Uncertainties are unavoidable in water-quality modeling and subsequent management decisions. Monte Carlo simulation and first-order uncertainty analysis (involving linearization at central values of the uncertain variables) have been frequently used to estimate probability distributions for water-quality model output due to their simplicity. Each method has its drawbacks: Monte Carlo simulation's is mainly computational time; and first-order analysis are mainly questions of accuracy and representativeness, especially for nonlinear systems and extreme conditions. An improved (advanced) first-order method is presented, where the linearization point varies to match the output level whose exceedance probability is sought. The advanced first-order method is tested on the Streeter-Phelps equation to estimate the probability distribution of critical dissolved-oxygen deficit and critical dissolved oxygen using two hypothetical examples from the literature. The advanced first-order method provides a close approximation of the exceedance probability for the Streeter-Phelps model output estimated by Monte Carlo simulation using less computer time - by two orders of magnitude - regardless of the probability distributions assumed for the uncertain model parameters.

  13. Design and Simulation of First Order Sigma-Delta Modulator Using LT spice Tool

    Directory of Open Access Journals (Sweden)

    Prince Kumar Pandey

    2014-07-01

    Full Text Available A switched-capacitor single-stage Sigma-Delta ADC with a first-order modulator is proposed. Efficient low power first Order 1-Bit Sigma-Delta ADC designed which accepts input signal bandwidth of 10 MHz. This circuitry performs the function of an analog-to-digital converter. A first-order 1-Bit Sigma-Delta (Σ-Δ modulator is designed, simulated and analyzed using LTspice standard 250nm CMOS technology power supply of 1.8V. The modulator is proved to be robustness, the high performance in stability. The simulations are compared with those from a traditional analog-to-digital converter to prove that Sigma-Delta is performing better with low power and area.

  14. Mass and Angular Momentum of Black Holes in Three Dimensional Gravity Theories with First Order Formalism

    CERN Document Server

    Nam, Soonkeon

    2016-01-01

    We apply the Wald formalism to obtain masses and angular momenta of black holes in three dimensional gravity theories using first order formalism. Wald formalism suggests mass and angular momentum of black hole as an integration of some charge variation form at its boundary. The action of the three dimensional gravity theories can be represented by the form including some auxiliary fields. As well-known examples we have calculated mass and angular momentum of some black holes in topologically massive gravity and new massive gravity theories using first order formalism. We have also calculated mass and angular momentum of BTZ black hole and new type black hole in minimal massive gravity theory with the action represented by first order formalism.

  15. Topological first-order vortices in a gauged CP(2 model

    Directory of Open Access Journals (Sweden)

    R. Casana

    2017-05-01

    Full Text Available We study time-independent radially symmetric first-order solitons in a CP(2 model interacting with an Abelian gauge field whose dynamics is controlled by the usual Maxwell term. In this sense, we develop a consistent first-order framework verifying the existence of a well-defined lower bound for the corresponding energy. We saturate such a lower bound by focusing on those solutions satisfying a particular set of coupled first-order differential equations. We solve these equations numerically using appropriate boundary conditions giving rise to regular structures possessing finite-energy. We also comment the main features these configurations exhibit. Moreover, we highlight that, despite the different solutions we consider for an auxiliary function β(r labeling the model (therefore splitting our investigation in two a priori distinct branches, all resulting scenarios engender the very same phenomenology, being physically equivalent.

  16. Topological first-order vortices in a gauged CP(2) model

    Science.gov (United States)

    Casana, R.; Dias, M. L.; da Hora, E.

    2017-05-01

    We study time-independent radially symmetric first-order solitons in a CP (2) model interacting with an Abelian gauge field whose dynamics is controlled by the usual Maxwell term. In this sense, we develop a consistent first-order framework verifying the existence of a well-defined lower bound for the corresponding energy. We saturate such a lower bound by focusing on those solutions satisfying a particular set of coupled first-order differential equations. We solve these equations numerically using appropriate boundary conditions giving rise to regular structures possessing finite-energy. We also comment the main features these configurations exhibit. Moreover, we highlight that, despite the different solutions we consider for an auxiliary function β (r) labeling the model (therefore splitting our investigation in two a priori distinct branches), all resulting scenarios engender the very same phenomenology, being physically equivalent.

  17. Precision Electroweak Measurements at FCC-ee

    CERN Document Server

    Tenchini, Roberto

    2014-01-01

    The prospects for electroweak precision measurements at the Future Circular Collider with electron-positron beams (FCC-ee) are discussed. The Z mass and width, as well as the value of the electroweak mixing angle, can be measured with very high precision at the Z pole thanks to an instantaneous luminosity five to six order of magnitudes larger than LEP. At centre-of-mass energies around 160 GeV, corresponding to the WW production threshold, the W mass can be determined very precisely with high-statistics cross section measurements at several energy points. Similarly, a very precise determination of the top mass can be provided by an energy scan at the $\\mathrm{t \\bar t}$ production threshold, around 350 GeV.

  18. Fate of Electroweak Vacuum during Preheating

    CERN Document Server

    Ema, Yohei; Nakayama, Kazunori

    2016-01-01

    Our electroweak vacuum may be metastable in light of the current experimental data of the Higgs/top quark mass. If this is really the case, high-scale inflation models require a stabilization mechanism of our vacuum during inflation. A possible candidate is the Higgs-inflaton/-curvature coupling because it induces an additional mass term to the Higgs during the slow roll regime. However, after the inflation, the additional mass term oscillates, and it can potentially destabilize our electroweak vacuum via production of large Higgs fluctuations during the inflaton oscillation era. In this paper, we study whether or not the Higgs-inflaton/-curvature coupling can save our vacuum by properly taking account of Higgs production during the preheating stage. We put upper bounds on the Higgs-inflaton/-curvature coupling, and discuss possible dynamics that might relax them.

  19. A Determination of Electroweak Parameters at HERA

    CERN Document Server

    Aktas, A; Anthonis, T; Aplin, S; Asmone, A; Astvatsatourov, A; Babaev, A; Backovic, S; Bähr, J; Baghdasaryan, A; Baranov, P; Barrelet, E; Bartel, Wulfrin; Baudrand, S; Baumgartner, S; Becker, J; Beckingham, M; Behnke, O; Behrendt, O; Belousov, A; Berger, C; Berger, N; Bizot, J C; Boenig, M O; Boudry, V; Bracinik, J; Brandt, G; Brisson, V; Brown, D P; Bruncko, Dusan; Büsser, F W; Bunyatyan, A; Buschhorn, G; Bystritskaya, L; Campbell, A J; Caron, S; Cassol-Brunner, F; Cerny, K; Cerny, V; Chekelian, V; Contreras, J G; Coughlan, J A; Cox, B E; Cozzika, G; Cvach, J; Dainton, J B; Dau, W D; Daum, K; De Boer, Y; Delcourt, B; de Roeck, A; Desch, Klaus; De Wolf, E A; Diaconu, C; Dodonov, V; Dubak, A; Eckerlin, G; Efremenko, V; Egli, S; Eichler, R; Eisele, F; Ellerbrock, M; Erdmann, W; Essenov, S; Falkewicz, A; Faulkner, P J W; Favart, L; Fedotov, A; Felst, R; Ferencei, J; Finke, L; Fleischer, M; Fleischmann, P; Fleming, Y H; Flucke, G; Fomenko, A; Foresti, I; Franke, G; Frisson, T; Gabathuler, E; Garutti, E; Gayler, J; Gerlich, C; Ghazaryan, S; Ginzburgskaya, S; Glazov, A; Glushkov, I; Görlich, L; Göttlich, M; Gogitidze, N; Gorbounov, S; Goyon, C; Grab, C; Greenshaw, T; Gregori, M; Grell, B R; Grindhammer, G; Gwilliam, C; Haidt, D; Hajduk, L; Hansson, M; Heinzelmann, G; Henderson, R C W; Henschel, H; Henshaw, O; Herrera-Corral, G; Hildebrandt, M; Hiller, K H; Hoffmann, D; Horisberger, R P; Hovhannisyan, A; Hreus, T; Hussain, S; Ibbotson, M; Ismail, M; Jacquet, M; Janauschek, L; Janssen, X; Jemanov, V; Jönsson, L B; Johnson, D P; Jung, A W; Jung, H; Kapichine, M; Katzy, J; Keller, N; Kenyon, I R; Kiesling, C; Klein, M; Kleinwort, C; Klimkovich, T; Kluge, T; Knies, G; Knutsson, A; Korbel, V; Kostka, P; Krastev, K; Kretzschmar, J; Kropivnitskaya, A; Krüger, K; Kuckens, J; Landon, M P J; Lange, W; Lastoviicka, T; Lastoviicka-Medin, G; Laycock, P; Lebedev, A; Leibenguth, G; Lendermann, V; Levonian, S; Lindfeld, L; Lipka, K; Liptaj, A; List, B; Lobodzinska, E; Loktionova, N; López-Fernandez, R; Lubimov, V; Lucaci-Timoce, A I; Lüders, H; Lüke, D; Lux, T; Lytkin, L; Makankine, A; Malden, N; Malinovskii, E I; Mangano, S; Marage, P; Marshall, R; Martisikova, M; Martyn, H U; Maxfield, S J; Meer, D; Mehta, A; Meier, K; Meyer, A B; Meyer, H; Meyer, J; Mikocki, S; Milcewicz-Mika, I; Milstead, D; Mladenov, D M; Mohamed, A; Moreau, F; Morozov, A; Morris, J V; Mozer, M U; Müller, K; Murn, P; Nankov, K; Naroska, Beate; Naumann, T; Newman, P R; Niebuhr, C; Nikiforov, A; Nikitin, D; Nowak, G; Nozicka, M; Oganezov, R; Olivier, B; Olsson, J E; Osman, S; Ozerov, D; Palichik, V; Panagoulias, I; Papadopoulou, T D; Pascaud, C; Patel, G D; Peez, M; Pérez, E; Perez-Astudillo, D; Perieanu, A; Petrukhin, A; Pitzl, D; Placakyte, R; Portheault, B; Povh, B; Prideaux, P; Raicevic, N; Reimer, P; Rimmer, A; Risler, C; Rizvi, E; Robmann, P; Roland, B; Roosen, R; Rostovtsev, A; Rurikova, Z; Rusakov, S; Salvaire, F; Sankey, D P C; Sauvan, E; Schatzel, S; Schilling, F P; Schmidt, S; Schmitt, S; Schmitz, C; Schoeffel, L; Schöning, A; Schultz-Coulon, H C; Sedlak, K; Sefkow, F; Shaw-West, R N; Shevyakov, I; Shtarkov, L N; Sloan, T; Smirnov, P; Soloviev, Yu; South, D; Spaskov, V; Specka, A; Stella, B; Stiewe, J; Strauch, I; Straumann, U; Tchoulakov, V; Thompson, G; Thompson, P D; Tomasz, F; Traynor, D; Truöl, P; Tsakov, I; Tsipolitis, G; Tsurin, I; Turnau, J; Tzamariudaki, E; Urban, M; Usik, A; Utkin, D; Valkár, S; Valkárová, A; Vallée, C; Van Mechelen, P; Vargas, A; Trevino; Vazdik, Ya A; Veelken, C; Vest, A; Vinokurova, S; Volchinski, V; Vujicic, B; Wacker, K; Wagner, J; Weber, G; Weber, R; Wegener, D; Werner, C; Werner, N; Wessels, M; Wessling, B; Wigmore, C; Wissing, C; Wolf, R; Wünsch, E; Xella, S M; Yan, W; Yeganov, V; Zaicek, J; Zaleisak, J; Zhang, Z; Zhelezov, A; Zhokin, A; Zhu, Y C; Zimmermann, J; Zimmermann, T; Zohrabyan, H; Zomer, F

    2006-01-01

    Using the deep inelastic e^+p and e^-p charged and neutral current scattering cross sections previously published, a combined electroweak and QCD analysis is performed to determine electroweak parameters accounting for their correlation with parton distributions. The data used have been collected by the H1 experiment in 1994-2000 and correspond to an integrated luminosity of 117.2 pb^{-1}. A measurement is obtained of the W propagator mass in charged current ep scattering. The weak mixing angle sin^2 theta_W is determined in the on-mass-shell renormalisation scheme. A first measurement at HERA is made of the light quark weak couplings to the Z^0 boson and a possible contribution of right-handed isospin components to the weak couplings is investigated.

  20. Electroweak instantons/sphalerons at VLHC?

    CERN Document Server

    Ringwald, Andreas

    2003-01-01

    There is a close analogy between electroweak instanton-induced baryon plus lepton number (B+L) violating processes in Quantum Flavor Dynamics (QFD) and hard QCD instanton-induced chirality violating processes in deep-inelastic scattering. In view of the recent information about the latter both from lattice simulations and from the H1 experiment at HERA, it seems worthwhile to reconsider electroweak B+L violation at high energies. We present a state of the art evaluation of QFD instanton-induced parton-parton cross-sections, as relevant at future high energy colliders in the hundreds of TeV regime, such as the projected Very Large Hadron Collider (VLHC). We find that the cross-sections are unobservably small in a conservative fiducial kinematical region inferred from the above mentioned QFD--QCD analogy. An extrapolation -- still compatible with lattice results and HERA -- beyond this conservative limit indicates possible observability at VLHC.