Gravity waves from the non-renormalizable electroweak vacua phase transition

Energy Technology Data Exchange (ETDEWEB)

Greenwood, Eric [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Physics; Vaudrevange, Pascal M. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Physics; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2010-11-15

It is currently believed that the Standard Model is an effective low energy theory which in principle may contain higher dimensional non-renormalizable operators. These operators may modify the standard model Higgs potential in many ways, one of which being the appearance of a second vacuum. For a wide range of parameters, this new vacuum becomes the true vacuum. It is then assumed that our universe is currently sitting in the false vacuum. Thus the usual second-order electroweak phase transition at early times will be followed by a second, first-order phase transition. In cosmology, a first-order phase transition is associated with the production of gravity waves. In this paper we present an analysis of the production of gravitational waves during such a second electroweak phase transition. We find that, for one certain range of parameters, the stochastic background of gravitational waves generated by bubble nucleation and collision have an amplitude which is estimated to be of order {omega}{sub GW}h{sup 2}{proportional_to}10{sup -11} at f=3 x 10{sup -4} Hz, which is within reach of the planned sensitivity of LISA. For another range of parameters, we find that the amplitude is estimated to be of order {omega}{sub GW}h{sup 2}{proportional_to} 0{sup -25} around f=10{sup 3} Hz, which is within reach of LIGO. Hence, it is possible to detect gravity waves from such a phase transition at two different detectors, with completely different amplitude and frequency ranges. (orig.)

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 co...... the associated models are testable at the upcoming Large Hadron Collider run two experiments....

Gravitational waves from the first order electroweak phase transition in the Z3 symmetric singlet scalar model*

Directory of Open Access Journals (Sweden)

Matsui Toshinori

2018-01-01

Full Text Available Among various scenarios of baryon asymmetry of the Universe, electroweak baryogenesis is directly connected with physics of the Higgs sector. We discuss spectra of gravitational waves which are originated by the strongly first order phase transition at the electroweak symmetry breaking, which is required for a successful scenario of electroweak baryogenesis. In the Z3 symmetric singlet scalar model, the significant gravitational waves are caused by the multi-step phase transition. We show that the model can be tested by measuring the characteristic spectra of the gravitational waves at future interferometers such as LISA and DECIGO.

Low temperature electroweak phase transition in the Standard Model with hidden scale invariance

Directory of Open Access Journals (Sweden)

Suntharan Arunasalam

2018-01-01

Full Text Available We discuss a cosmological phase transition within the Standard Model which incorporates spontaneously broken scale invariance as a low-energy theory. In addition to the Standard Model fields, the minimal model involves a light dilaton, which acquires a large vacuum expectation value (VEV through the mechanism of dimensional transmutation. Under the assumption of the cancellation of the vacuum energy, the dilaton develops a very small mass at 2-loop order. As a result, a flat direction is present in the classical dilaton-Higgs potential at zero temperature while the quantum potential admits two (almost degenerate local minima with unbroken and broken electroweak symmetry. We found that the cosmological electroweak phase transition in this model can only be triggered by a QCD chiral symmetry breaking phase transition at low temperatures, T≲132 MeV. Furthermore, unlike the standard case, the universe settles into the chiral symmetry breaking vacuum via a first-order phase transition which gives rise to a stochastic gravitational background with a peak frequency ∼10−8 Hz as well as triggers the production of approximately solar mass primordial black holes. The observation of these signatures of cosmological phase transitions together with the detection of a light dilaton would provide a strong hint of the fundamental role of scale invariance in particle physics.

Gravitational waves from a very strong electroweak phase transition

Energy Technology Data Exchange (ETDEWEB)

Leitao, Leonardo; Mégevand, Ariel, E-mail: lleitao@mdp.edu.ar, E-mail: megevand@mdp.edu.ar [IFIMAR (UNMdP-CONICET), Departamento de Física, Facultad de Ciencias Exactas y Naturales, UNMdP, Deán Funes 3350, (7600) Mar del Plata (Argentina)

2016-05-01

We investigate the production of a stochastic background of gravitational waves in the electroweak phase transition. We consider extensions of the Standard Model which can give very strongly first-order phase transitions, such that the transition fronts either propagate as detonations or run away. To compute the bubble wall velocity, we estimate the friction with the plasma and take into account the hydrodynamics. We track the development of the phase transition up to the percolation time, and we calculate the gravitational wave spectrum generated by bubble collisions, magnetohydrodynamic turbulence, and sound waves. For the kinds of models we consider, we find parameter regions for which the gravitational waves are potentially observable at the planned space-based interferometer eLISA. In such cases, the signal from sound waves is generally dominant, while that from bubble collisions is the least significant of them. Since the sound waves and turbulence mechanisms are diminished for runaway walls, the models with the best prospects of detection at eLISA are those which do not have such solutions. In particular, we find that heavy extra bosons provide stronger gravitational wave signals than tree-level terms.

Critical bubbles and fluctuations at the electroweak phase transition

CERN Document Server

Kripfganz, J; Schmidt, M G

1995-01-01

We discuss the critical bubbles of the electroweak phase transition using an effective high-temperature 3-dimensional action for the Higgs field \\varphi. The separate integration of gauge and Goldstone boson degrees of freedom is conveniently described in the 't Hooft-Feynman covariant background gauge. The effective dimensionless gauge coupling g_3(T)^2 in the broken phase is well behaved throughout the phase transition. However, the behavior of the one-loop Z(\\varphi) factors of the Higgs and gauge kinetic terms signalizes the breakdown of the derivative expansion and of the perturbative expansion for a range of small \\varphi values increasing with the Higgs mass m_H. Taking a functional S_z[\\varphi] with constant Z(\\varphi)=z instead of the full non-local effective action in some neighborhood of the saddlepoint we are calculating the critical bubbles for several temperatures. The fluctuation determinant is calculated to high accuracy using a variant of the heat kernel method. It gives a strong suppression ...

Gravitational waves from the electroweak phase transition

International Nuclear Information System (INIS)

Leitao, Leonardo; Mégevand, Ariel; Sánchez, Alejandro D.

2012-01-01

We study the generation of gravitational waves in the electroweak phase transition. We consider a few extensions of the Standard Model, namely, the addition of scalar singlets, the minimal supersymmetric extension, and the addition of TeV fermions. For each model we consider the complete dynamics of the phase transition. In particular, we estimate the friction force acting on bubble walls, and we take into account the fact that they can propagate either as detonations or as deflagrations preceded by shock fronts, or they can run away. We compute the peak frequency and peak intensity of the gravitational radiation generated by bubble collisions and turbulence. We discuss the detectability by proposed spaceborne detectors. For the models we considered, runaway walls require significant fine tuning of the parameters, and the gravitational wave signal from bubble collisions is generally much weaker than that from turbulence. Although the predicted signal is in most cases rather low for the sensitivity of LISA, models with strongly coupled extra scalars reach this sensitivity for frequencies f ∼ 10 −4 Hz, and give intensities as high as h 2 Ω GW ∼ 10 −8

3-dimensional lattice studies of the electroweak phase transition at MHiggs∼ 70 GeV

International Nuclear Information System (INIS)

Guertler, M.; Perlt, H.; Schiller, A.; Ilgenfritz, E.M.; Kripfganz, J.

1996-06-01

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 ∼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. (orig.)

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.)

The electroweak phase transition in models with gauge singlets

International Nuclear Information System (INIS)

Ahriche, A.

2007-01-01

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 Ω(T c )/T c >or similar 1, where Ω = (v 2 + (x - x 0 ) 2 ) ( 1)/(2) and x(x 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 c /T 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.)

Gravitational waves from a first-order electroweak phase transition: a brief review.

Science.gov (United States)

Weir, David J

2018-03-06

We review the production of gravitational waves by an electroweak first-order phase transition. The resulting signal is a good candidate for detection at next-generation gravitational wave detectors, such as LISA. Detection of such a source of gravitational waves could yield information about physics beyond the Standard Model that is complementary to that accessible to current and near-future collider experiments. We summarize efforts to simulate and model the phase transition and the resulting production of gravitational waves.This article is part of the Theo Murphy meeting issue 'Higgs cosmology'. © 2018 The Author(s).

Thermal equilibrium during the electroweak phase transition

International Nuclear Information System (INIS)

Tetradis, N.

1991-12-01

The effective potential for the standard model develops a barrier, at temperatures around the electroweak scale, which separates the minimum at zero field and a deeper non-zero minimum. This could create out of equilibrium conditions by inducing the localization of the Higgs field in a metastable state around zero. In this picture vacuum decay would occur through bubble nucleation. I show that there is an upper bound on the Higgs mass for the above scenario to be realized. The barrier must be high enough to prevent thermal fluctuations of the Higgs expectation value from establishing thermal equilibrium between the two minima. The upper bound is estimated to be lower than the experimental lower limit. This is also imposes constraints on extensions of the standard model constructed in order to generate a strongly first order phase transition. (orig.)

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

International Nuclear Information System (INIS)

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

2017-01-01

The discovery of the Higgs boson by the LHC experiments ATLAS and CMS has marked a milestone for particle physics. Yet, there are still many open questions that cannot be answered within the Standard Model (SM). For example, the generation of the observed matter-antimatter asymmetry in the universe through baryogenesis can only be explained qualitatively in the SM. A simple extension of the SM compatible with the current theoretical and experimental constraints is given by the 2-Higgs-Doublet Model (2HDM) where a second Higgs doublet is added to the Higgs sector. We investigate the possibility of a strong first order electroweak phase transition in the CP-conserving 2HDM type I and type II where either of the CP-even Higgs bosons is identified with the SM-like Higgs boson. The renormalisation that we apply on the loop-corrected Higgs potential allows us to efficiently scan the 2HDM parameter space and simultaneously take into account all relevant theoretical and up-to-date experimental constraints. The 2HDM parameter regions found to be compatible with the applied constraints and a strong electroweak phase transition are analysed systematically. Our results show that there is a strong interplay between the requirement of a strong phase transition and collider phenomenology with testable implications for searches at the LHC.

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

Energy Technology Data Exchange (ETDEWEB)

Basler, P.; Krause, M.; Mühlleitner, M. [Institute for Theoretical Physics, Karlsruhe Institute of Technology,Wolfgang-Gaede-Str. 1, 76131 Karlsruhe (Germany); Wittbrodt, J. [Institute for Theoretical Physics, Karlsruhe Institute of Technology,Wolfgang-Gaede-Str. 1, 76131 Karlsruhe (Germany); Deutsches Elektronen-Synchrotron DESY,Notkestraße 85, D-22607 Hamburg (Germany); Wlotzka, A. [Institute for Theoretical Physics, Karlsruhe Institute of Technology,Wolfgang-Gaede-Str. 1, 76131 Karlsruhe (Germany)

2017-02-23

The discovery of the Higgs boson by the LHC experiments ATLAS and CMS has marked a milestone for particle physics. Yet, there are still many open questions that cannot be answered within the Standard Model (SM). For example, the generation of the observed matter-antimatter asymmetry in the universe through baryogenesis can only be explained qualitatively in the SM. A simple extension of the SM compatible with the current theoretical and experimental constraints is given by the 2-Higgs-Doublet Model (2HDM) where a second Higgs doublet is added to the Higgs sector. We investigate the possibility of a strong first order electroweak phase transition in the CP-conserving 2HDM type I and type II where either of the CP-even Higgs bosons is identified with the SM-like Higgs boson. The renormalisation that we apply on the loop-corrected Higgs potential allows us to efficiently scan the 2HDM parameter space and simultaneously take into account all relevant theoretical and up-to-date experimental constraints. The 2HDM parameter regions found to be compatible with the applied constraints and a strong electroweak phase transition are analysed systematically. Our results show that there is a strong interplay between the requirement of a strong phase transition and collider phenomenology with testable implications for searches at the LHC.

Gravity waves as a probe of the Hubble expansion rate during an electroweak scale phase transition

International Nuclear Information System (INIS)

Chung, Daniel J. H.; Zhou Peng

2010-01-01

Just as big bang nucleosynthesis allows us to probe the expansion rate when the temperature of the Universe was around 1 MeV, the measurement of gravity waves from electroweak scale first order phase transitions may allow us to probe the expansion rate when the temperature of the Universe was at the electroweak scale. We compute the simple transformation rule for the gravity wave spectrum under the scaling transformation of the Hubble expansion rate. We then apply this directly to the scenario of quintessence kination domination and show how gravity wave spectra would shift relative to Laser Interferometer Space Antenna and Big Bang Observer projected sensitivities.

Gravitational waves from a supercooled electroweak phase transition and their detection with pulsar timing arrays

Energy Technology Data Exchange (ETDEWEB)

Kobakhidze, Archil; Lagger, Cyril; Manning, Adrian [University of Sydney, ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, Sydney, NSW (Australia); Yue, Jason [National Taiwan Normal University, Department of Physics, Taipei (China)

2017-08-15

We investigate the properties of a stochastic gravitational wave background produced by a first-order electroweak phase transition in the regime of extreme supercooling. We study a scenario whereby the percolation temperature that signifies the completion of the transition, T{sub p}, is as low as a few MeV (nucleosynthesis temperature), while most of the true vacuum bubbles are formed much earlier at the nucleation temperature, T{sub n} ∝ 50 GeV. This implies that the gravitational wave spectrum is mainly produced by the collisions of large bubbles and characterised by a large amplitude and a peak frequency as low as f ∝ 10{sup -9}-10{sup -7} Hz. We show that such a scenario can occur in (but not limited to) a model based on a non-linear realisation of the electroweak gauge group, so that the Higgs vacuum configuration is altered by a cubic coupling. In order to carefully quantify the evolution of the phase transition of this model over such a wide temperature range we go beyond the usual fast transition approximation, taking into account the expansion of the Universe as well as the behaviour of the nucleation probability at low temperatures. Our computation shows that there exists a range of parameters for which the gravitational wave spectrum lies at the edge between the exclusion limits of current pulsar timing array experiments and the detection band of the future Square Kilometre Array observatory. (orig.)

Probing Electroweak Phase Transition via Enhanced Di-Higgs Production

Energy Technology Data Exchange (ETDEWEB)

Carena, Marcela [Chicago U., KICP; Liu, Zhen [Fermilab; Riembau, Marc [DESY

2018-01-02

We consider a singlet extension of the Standard Model (SM) with a spontaneous $Z_2$ breaking and study the gluon-gluon fusion production of the heavy scalar, with subsequent decay into a pair of SM-like Higgs bosons. We find that an on-shell interference effect can notably enhance the resonant di-Higgs production rate up to 40\\%. In addition, consistently taking into account both the on-shell and off-shell interference effects between the heavy scalar and the SM di-Higgs diagrams significantly improves the HL-LHC and HE-LHC reach in this channel. As an example, within an effective field theory analysis in an explicitly $Z_2$ breaking scenario, we further discuss the potential to probe the parameter region compatible with a first order electroweak phase transition. Our analysis is applicable for general potentials of the singlet extension of the SM as well as for more general resonance searches.

On the nature of the electroweak phase sition and its cosmological consequences

International Nuclear Information System (INIS)

Servant, Geraldine

2011-01-01

Full text: The Large Hadron Collider will take experiments into a new energy domain beyond the standard model of strong and electroweak interactions. As the LHC will unveil the mysteries of the electroweak symmetry breaking, this will also have far-reaching implications for cosmology. This concerns in particular the fundamental question of the matter-antimatter asymmetry of the Universe. One of the best-motivated mechanism for generating the baryon asymmetry of the universe relies on a first-order electroweak phase transition. I will present some well-motivated extensions of the standard model that naturally lead to a first-order phase transition. Interestingly, this has strong implications for gravity wave physics. I will discuss how a gravity wave detector and space interferometer such as Lisa, which would turn out to be a completely independent window on the electroweak scale, could complement the information provided by the LHC. (author)

Cosmological phase transitions

International Nuclear Information System (INIS)

Kolb, E.W.

1993-10-01

If modern ideas about the role of spontaneous symmetry breaking in fundamental physics are correct, then the Universe should have undergone a series of phase transitions early in its history. The study of cosmological phase transitions has become an important aspect of early-Universe cosmology. In this lecture I review some very recent work on three aspects of phase transitions: the electroweak transition, texture, and axions

First order electroweak phase transition

International Nuclear Information System (INIS)

Buchmueller, W.; Fodor, Z.

1993-01-01

In this work, the authors have studied the phase transition in the SU(2)gauge theory at finite temperature. The authors' improved perturbative approach does not suffer from the infrared problems appearing in the ordinary loop expansion. The authors have calculated the effective potential up to cubic terms in the couplings. The higher order terms suggest that the method is reliable for Higgs masses smaller than 80 GeV. The authors have obtained a non-vanishing magnetic mass which further weakens the transitions. By use of Langer's theory of metastability, the authors have calculated the nucleation rate for critical bubbles and have discussed some cosmological consequences. For m H <80 GeV the phase transition is first order and proceeds via bubble nucleation and growth. The thin wall approximation is only marginally applicable. Since the phase transition is quite weak SM baryogenesis is unlikely. 8 refs., 5 figs

Properties of high-density matter in the electroweak symmetric phase

International Nuclear Information System (INIS)

Chandra, D.; Goyal, A.

1992-01-01

We examine the bulk properties of matter at high densities and finite temperatures in the phase where electroweak symmetry is exact and fermions are massless, by taking the strong interactions into account perturbatively to lowest order in the quark-gluon chromodynamic coupling constant α c . We also discuss the possibility of a phase transition of strange quark matter into this high-density matter in the electroweak symmetric phase at densities likely to be present in the core of dense neutron stars or collapsing stars. Finally, we study the properties of finite-size chunks of this matter by taking surface effects into account and give an estimate of the surface tension

Semi-analytic calculation of the gravitational wave signal from the electroweak phase transition for general quartic scalar effective potentials

International Nuclear Information System (INIS)

Kehayias, John; Profumo, Stefano

2010-01-01

Upcoming gravitational wave (GW) detectors might detect a stochastic background of GWs potentially arising from many possible sources, including bubble collisions from a strongly first-order electroweak phase transition. We investigate whether it is possible to connect, via a semi-analytical approximation to the tunneling rate of scalar fields with quartic potentials, the GW signal through detonations with the parameters entering the potential that drives the electroweak phase transition. To this end, we consider a finite temperature effective potential similar in form to the Higgs potential in the Standard Model (SM). In the context of a semi-analytic approximation to the three dimensional Euclidean action, we derive a general approximate form for the tunneling temperature and the relevant GW parameters. We explore the GW signal across the parameter space describing the potential which drives the phase transition. We comment on the potential detectability of a GW signal with future experiments, and physical relevance of the associated potential parameters in the context of theories which have effective potentials similar in form to that of the SM. In particular we consider singlet, triplet, higher dimensional operators, and top-flavor extensions to the Higgs sector of the SM. We find that the addition of a temperature independent cubic term in the potential, arising from a gauge singlet for instance, can greatly enhance the GW power. The other parameters have milder, but potentially noticeable, effects

Probing the electroweak phase transition via enhanced di-Higgs boson production

Science.gov (United States)

Carena, Marcela; Liu, Zhen; Riembau, Marc

2018-05-01

We consider a singlet extension of the standard model (SM) with a spontaneous Z2 breaking and study the gluon-gluon fusion production of the heavy scalar, with subsequent decay into a pair of SM-like Higgs bosons. We find that an on-shell interference effect can notably enhance the resonant di-Higgs production rate up to 40%. In addition, consistently taking into account both the on-shell and off-shell interference effects between the heavy scalar and the SM di-Higgs diagrams significantly improves the HL-LHC and HE-LHC reach in this channel. As an example, within an effective field theory analysis in an explicitly Z2 breaking scenario, we further discuss the potential to probe the parameter region compatible with a first-order electroweak phase transition. Our analysis is applicable for general potentials of the singlet extension of the SM as well as for more general resonance searches.

Holography and the Electroweak Phase Transition

CERN Document Server

Creminelli, Paolo; Rattazzi, Riccardo; Creminelli, Paolo; Nicolis, Alberto; Rattazzi, Riccardo

2002-01-01

We study through holography the compact Randall-Sundrum (RS) model at finite temperature. In the presence of radius stabilization, the system is described at low enough temperature by the RS solution. At high temperature it is described by the AdS-Schwarzshild solution with an event horizon replacing the TeV brane. We calculate the transition temperature T_c between the two phases and we find it to be somewhat smaller than the TeV scale. Assuming that the Universe starts out at T >> T_c and cools down by expansion, we study the rate of the transition to the RS phase. We find that the transition is too slow and the Universe ends up in an old inflation scenario unless tight bounds are satisfied by the model parameters. In particular we find that the AdS curvature must be comparable to the 5D Planck mass and that the radius stabilization mechanism must lead to a sizeable distortion of the basic RS metric.

The Ward-Takahashi identities to describe nucleon and pion electroweak transitions

International Nuclear Information System (INIS)

Bunatyan, G.G.

2008-01-01

For nucleons and pions, the relations among the propagators and vertex functions to describe the vector electroweak transitions are acquired as immediate corollary of symmetries of the hadron strong and electroweak interactions. A point of value is that the considered system comprises strongly interacting hadrons of different sorts. The electromagnetic corrections to hadron vertex functions and propagators are taken into account up to e 2 order. The sequels are discussed in the light of calculation of the radiative corrections in describing the nucleon and pion electroweak transitions

Gravitational radiation from first-order phase transitions

International Nuclear Information System (INIS)

Child, Hillary L.; Giblin, John T. Jr.

2012-01-01

It is believed that first-order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles using only scalar fields, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase enhances this radiation even in the absence of a coupled fluid or turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier

Gravitational radiation from first-order phase transitions

Energy Technology Data Exchange (ETDEWEB)

Child, Hillary L.; Giblin, John T. Jr., E-mail: childh@kenyon.edu, E-mail: giblinj@kenyon.edu [Department of Physics, Kenyon College, 201 North College Road, Gambier, OH 43022 (United States)

2012-10-01

It is believed that first-order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles using only scalar fields, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase enhances this radiation even in the absence of a coupled fluid or turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier.

Gravitational waves from phase transition in split NMSSM

Science.gov (United States)

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

2018-04-01

We discuss gravitational wave signal from the strongly first order electroweak phase transition in the split NMSSM. We find that for sets of parameters predicting successful electroweak baryogenesis the gravitational wave signal can be within the reach of future experiments LISA, BBO and Ultimate DECIGO.

Quark–hadron phase transition in massive gravity

Energy Technology Data Exchange (ETDEWEB)

Atazadeh, K., E-mail: atazadeh@azaruniv.ac.ir

2016-11-15

We study the quark–hadron phase transition in the framework of massive gravity. We show that the modification of the FRW cosmological equations leads to the quark–hadron phase transition in the early massive Universe. Using numerical analysis, we consider that a phase transition based on the chiral symmetry breaking after the electroweak transition, occurred at approximately 10 μs after the Big Bang to convert a plasma of free quarks and gluons into hadrons.

A self consistent study of the phase transition in the scalar electroweak theory at finite temperature

International Nuclear Information System (INIS)

Kerres, U.; Mack, G.; Palma, G.

1994-12-01

We propose the study of the phase transition in the scalar electroweak theory at finite temperature by a two-step method. It combines i) dimensional reduction to a 3-dimensional lattice theory via perturbative blockspin transformation, and ii) either further real space renormalization group transformations, or solution of gap equations, for the 3d lattice theory. A gap equation can be obtained by using the Peierls inequality to find the best quadratic approximation to the 3d action. This method avoids the lack of self consistency of the usual treatments which do not separate infrared and UV-problems by introduction of a lattice cutoff. The effective 3d lattice action could also be used in computer simulations. (orig.)

A self consistent study of the phase transition in the scalar electroweak theory at finite temperature

International Nuclear Information System (INIS)

Kerres, U.

1995-01-01

We propose the study of the phase transition in the scalar electroweak theory at finite temperature by a two-step method. It combines i) dimensional reduction to a 3-dimensional lattice theory via perturbative blockspin transformation, and ii) either further real space renormalization group transformations, or solution of gap equations, for the 3d lattice theory. A gap equation can be obtained by using the Peierls inequality to find the best quadratic approximation to the 3d action. This method avoids the lack of self consistency of the usual treatments which do not separate infrared and UV-problems by introduction of a lattice cutoff. The effective 3d lattice action could also be used in computer simulations. ((orig.))

Electroweak baryogenesis with primordial hypermagnetic fields

International Nuclear Information System (INIS)

Ayala, Alejandro; Pallares, Gabriel; Besprosvany, Jaime; Piccinelli, Gabriella

2002-01-01

Primordial magnetic fields, independently of their origin, could have had a significant influence over several physical processes that took place during the evolution of the early universe, in particular baryogenesis. Recall that for temperatures above the electroweak phase transition (T > 100 GeV), the symmetry of the standard model corresponded to the U(1)y hypercharge group, instead of the U(1)em electromagnetic group and are therefore properly called hypermagnetic fields. In this work, we show that during a first order electroweak phase transition, the presence of hypermagnetic fields produces an axial charge segregation in the reflection and transmission of fermions off the true vacuum bubbles. We also comment on the possible consequences that these processes have for the generation of baryon number during the phase transition

Opening the window for electroweak baryogenesis

CERN Document Server

Carena, M S; Wagner, C E M

1996-01-01

We perform an analysis of the behaviour of the electroweak phase transition in the Minimal Supersymmetric Standard Model, in the presence of light stops. We show that, in previously unexplored regions of parameter space, the order parameter v(T_c)/T_c can become significantly larger than one, for values of the Higgs and supersymmetric particle masses consistent with the present experimental bounds. This implies that baryon number can be efficiently generated at the electroweak phase transition. As a by-product of this study, we present an analysis of the problem of colour breaking minima at zero and finite temperature, and we use it to investigate the region of parameter space preferred by the best fit to the present precision electroweak measurement data, in which the left-handed stops are much heavier than the right-handed ones.

Breaking of electroweak symmetry: origin and effects

International Nuclear Information System (INIS)

Delaunay, C.

2008-10-01

The Higgs boson appears as the corner stone of high energy physics, it might be the cause of the excess of matter that led to the formation of the structures of the universe and it seems that it drives the breaking of the electroweak symmetry. Moreover, when the stability at low energies of the Higgs boson is assured by an extra space dimension, it appears that this extra dimension can explain most issues in the flavor physics that are not understood by the standard model. The first chapter presents the main tools of effective field theories, the role of experimental data in the construction of theories valid beyond the standard model is discussed. The second chapter focuses on the electroweak baryogenesis that allows the testing of new physics via the electroweak phase transition. We detail the calculation of a Higgs potential at finite temperature. We follow the dynamics of the phase transition including nucleation an supercooling. Finally we investigate the prospects of gravity wave detection to see the effects of a strong electroweak phase transition. The 2 last chapters are dedicated to the physics of extra-dimension. The properties of the dynamics of scalar, vector fields with a 1/2 spin plunged in a 5 d. Anti de Sitter geometry are reviewed. We present a model of lepton masses and mixings based on the A 4 non-Abelian discrete symmetry. It is shown that this model does not contradict the tests of electroweak precision. (A.C.)

Lower bound on the electroweak wall velocity from hydrodynamic instability

Energy Technology Data Exchange (ETDEWEB)

Mégevand, Ariel; Membiela, Federico Agustín; Sánchez, Alejandro D., E-mail: megevand@mdp.edu.ar, E-mail: membiela@mdp.edu.ar, E-mail: sanchez@mdp.edu.ar [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)

2015-03-01

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.

Lower bound on the electroweak wall velocity from hydrodynamic instability

International Nuclear Information System (INIS)

Mégevand, Ariel; Membiela, Federico Agustín; Sánchez, Alejandro D.

2015-01-01

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

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.

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.

Status of electroweak phase transition and baryogenesis

Indian Academy of Sciences (India)

It is possible that the universe has undergone a number of phase transitions, as illustrated in table 1. .... А, and perturbation theory breaks down for heavy Higgs bosons, ..... This is good news, since the neutron and electric dipole moment.

Phase transition and gravitational wave phenomenology of scalar conformal extensions of the Standard Model

Energy Technology Data Exchange (ETDEWEB)

Marzola, Luca; Racioppi, Antonio; Vaskonen, Ville [National Institute of Chemical Physics and Biophysics, Tallinn (Estonia)

2017-07-15

Thermal corrections in classically conformal models typically induce a strong first-order electroweak phase transition, thereby resulting in a stochastic gravitational background that could be detectable at gravitational wave observatories. After reviewing the basics of classically conformal scenarios, in this paper we investigate the phase transition dynamics in a thermal environment and the related gravitational wave phenomenology within the framework of scalar conformal extensions of the Standard Model. We find that minimal extensions involving only one additional scalar field struggle to reproduce the correct phase transition dynamics once thermal corrections are accounted for. Next-to-minimal models, instead, yield the desired electroweak symmetry breaking and typically result in a very strong gravitational wave signal. (orig.)

Electroweak bubble wall speed limit

Energy Technology Data Exchange (ETDEWEB)

Bödeker, Dietrich [Fakultät für Physik, Universität Bielefeld, 33501 Bielefeld (Germany); Moore, Guy D., E-mail: bodeker@physik.uni-bielefeld.de, E-mail: guymoore@ikp.physik.tu-darmstadt.de [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 2, 64289 Darmstadt (Germany)

2017-05-01

In extensions of the Standard Model with extra scalars, the electroweak phase transition can be very strong, and the bubble walls can be highly relativistic. We revisit our previous argument that electroweak bubble walls can 'run away,' that is, achieve extreme ultrarelativistic velocities γ ∼ 10{sup 14}. We show that, when particles cross the bubble wall, they can emit transition radiation. Wall-frame soft processes, though suppressed by a power of the coupling α, have a significance enhanced by the γ-factor of the wall, limiting wall velocities to γ ∼ 1/α. Though the bubble walls can move at almost the speed of light, they carry an infinitesimal share of the plasma's energy.

Bino-driven electroweak baryogenesis with highly suppressed electric dipole moments

Energy Technology Data Exchange (ETDEWEB)

Li Yingchuan [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)], E-mail: yli@physics.wisc.edu; Profumo, Stefano [Department of Physics and Santa Cruz Institute for Particle Physics, University of California, 1156 High St., Santa Cruz, CA 95064 (United States)], E-mail: profumo@scipp.ucsc.edu; Ramsey-Musolf, Michael [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States)], E-mail: mjrm@physics.wisc.edu

2009-03-09

It is conventional wisdom that successful electroweak baryogenesis in the Minimal Supersymmetric extension of the Standard Model (MSSM) is in tension with the non-observation of electric dipole moments (EDMs), since the level of CP-violation responsible for electroweak baryogenesis is believed to generate unavoidably large EDMs. We show that CP-violation in the bino-Higgsino sector of the MSSM can account for successful electroweak baryogenesis without inducing large EDMs. This observation weakens the correlation between electroweak baryogenesis and EDMs, and makes the bino-driven electroweak baryogenesis scenario the least constrained by EDM limits. Taking this observation together with the requirement of a strongly first-order electroweak phase transition, we argue that a bino-driven scenario with a light stop is the most phenomenologically viable MSSM electroweak baryogenesis scenario.

Bino-driven electroweak baryogenesis with highly suppressed electric dipole moments

International Nuclear Information System (INIS)

Li Yingchuan; Profumo, Stefano; Ramsey-Musolf, Michael

2009-01-01

It is conventional wisdom that successful electroweak baryogenesis in the Minimal Supersymmetric extension of the Standard Model (MSSM) is in tension with the non-observation of electric dipole moments (EDMs), since the level of CP-violation responsible for electroweak baryogenesis is believed to generate unavoidably large EDMs. We show that CP-violation in the bino-Higgsino sector of the MSSM can account for successful electroweak baryogenesis without inducing large EDMs. This observation weakens the correlation between electroweak baryogenesis and EDMs, and makes the bino-driven electroweak baryogenesis scenario the least constrained by EDM limits. Taking this observation together with the requirement of a strongly first-order electroweak phase transition, we argue that a bino-driven scenario with a light stop is the most phenomenologically viable MSSM electroweak baryogenesis scenario

Miscellaneous results on the electroweak phase transition

International Nuclear Information System (INIS)

Ilgenfritz, E.M.; Schiller, A.

1994-12-01

We present new 4-D Monte Carlo results characterizing the strength of the finite temperature phase transition for Higgs/W mass ratios 1.0 and 0.6, obtained on isotropic lattices mainly with N s = 16, N t = 2. We discuss the distribution of a gauge invariant block spin order parameter, estimating the Higgs condensate Φ c at T c . We use the Potvin/Rebbi method in order to find the interface tension α/T c 3 . We demonstrate how the multi-histogram method (giving free energy differences) can be used to avoid the limiting procedure δ K → 0. From pure-phase histograms at K c , extrapolated with the help of this method, we estimate the latent heat Δε/T c 4 . Actual time series at lower Higgs mass require blocking in order to determine the jump of the lattice observables. (orig.)

Natural cold baryogenesis from strongly interacting electroweak symmetry breaking

International Nuclear Information System (INIS)

Konstandin, Thomas; Servant, Géraldine

2011-01-01

The mechanism of ''cold electroweak baryogenesis'' has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on any particular UV completion but only on a stage of supercooling ended by a first-order phase transition in the evolution of the universe, which can be natural if there is nearly conformal dynamics at the TeV scale. Besides, baryon-number violation originates from the Standard Model only

Simulating the electroweak phase transition in the SU(2) Higgs model

International Nuclear Information System (INIS)

Fodor, Z.; Hein, J.; Jansen, K.; Jaster, A.; Montvay, I.

1994-09-01

Numerical simulations are performed to study the finite temperature phase transition in the SU(2) Higgs model on the lattice. In the presently investigated range of the Higgs boson mass, below 50 GeV, the phase transition turns out to be of first order and its strength is rapidly decreasing with increasing Higgs boson mass. In order to control the systematic errors, we also perform studies of scaling violations and of finite volume effects. (orig.)

Breaking of electroweak symmetry: origin and effects; Brisure de symetrie electrobaible: origine et consequence

Energy Technology Data Exchange (ETDEWEB)

Delaunay, C

2008-10-15

The Higgs boson appears as the corner stone of high energy physics, it might be the cause of the excess of matter that led to the formation of the structures of the universe and it seems that it drives the breaking of the electroweak symmetry. Moreover, when the stability at low energies of the Higgs boson is assured by an extra space dimension, it appears that this extra dimension can explain most issues in the flavor physics that are not understood by the standard model. The first chapter presents the main tools of effective field theories, the role of experimental data in the construction of theories valid beyond the standard model is discussed. The second chapter focuses on the electroweak baryogenesis that allows the testing of new physics via the electroweak phase transition. We detail the calculation of a Higgs potential at finite temperature. We follow the dynamics of the phase transition including nucleation an supercooling. Finally we investigate the prospects of gravity wave detection to see the effects of a strong electroweak phase transition. The 2 last chapters are dedicated to the physics of extra-dimension. The properties of the dynamics of scalar, vector fields with a 1/2 spin plunged in a 5 d. Anti de Sitter geometry are reviewed. We present a model of lepton masses and mixings based on the A{sub 4} non-Abelian discrete symmetry. It is shown that this model does not contradict the tests of electroweak precision. (A.C.)

Enabling electroweak baryogenesis through dark matter

International Nuclear Information System (INIS)

Lewicki, Marek; Rindler-Daller, Tanja; 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 expansion rate increases by six orders of magnitude.

Natural cold baryogenesis from strongly interacting electroweak symmetry breaking

Energy Technology Data Exchange (ETDEWEB)

Konstandin, Thomas; Servant, Géraldine, E-mail: tkonstan@cern.ch, E-mail: geraldine.servant@cern.ch [CERN Physics Department, Theory Division, CH-1211 Geneva 23 (Switzerland)

2011-07-01

The mechanism of ''cold electroweak baryogenesis'' has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on any particular UV completion but only on a stage of supercooling ended by a first-order phase transition in the evolution of the universe, which can be natural if there is nearly conformal dynamics at the TeV scale. Besides, baryon-number violation originates from the Standard Model only.

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.

Electroweak Baryogenesis and Higgs and Stop Searches at LEP and the Tevatron

CERN Document Server

Carena, M S; Wagner, C E M

1998-01-01

It has been recently shown that the observed baryon number may originate at the electroweak phase transition, provided that the Higgs boson and the lightest stop are sufficiently light. In this work, we perform a detailed analysis, including all dominant two-loop finite temperature corrections to the Higgs effective potential, as well as the non-trivial effects proceeding from the mixing in the stop sector, to define the region of parameter space for which electroweak baryogenesis can happen. The limits on the stop and Higgs masses are obtained by taking into account the experimental bounds on these quantities, as well as those coming from the requirement of avoiding dangerous color breaking minima. We find for the Higgs mass $m_h \\simlt 105$ GeV, while the stop mass may be close to the present experimental bound and must be smaller than, or of order of, the top quark mass. These results provide a very strong motivation for further non-perturbative analysis of the electroweak phase transition, as well as for ...

CP-violating profile of the electroweak bubble wall

Energy Technology Data Exchange (ETDEWEB)

Funakubo, Koichi [Saga Univ. (Japan). Dept. of Physics; Kakuto, Akira; Otsuki, Shoichiro; Takenaga, Kazunori; Toyoda, Fumihiko

1995-11-01

In any scenario of the electroweak baryogenesis, the profile of the CP violating bubble wall, created at the first-order phase transition, plays an essential role. We attempt to determine it by solving the equations of motion for the scalars in the two-Higgs-doublet model at the transition temperature. According to the parameters in the potential, we found three solutions. Two of them smoothly connect the CP-violating broken phase and the symmetric phase, while the other connects CP-conserving vacua but violates CP in the intermediate region. We also estimate the chiral charge flux, which will be turned into the baryon density in the symmetric phase by the sphaleron process. (author).

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.

Natural Cold Baryogenesis from Strongly Interacting Electroweak Symmetry Breaking

CERN Document Server

Konstandin, Thomas

2011-01-01

The mechanism of "cold electroweak baryogenesis" has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on...

The hierarchy problem of the electroweak standard model revisited

International Nuclear Information System (INIS)

Jegerlehner, Fred

2013-05-01

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.

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.

Electroweak baryogenesis and Higgs and stop searches at LEP and the Tevatron

International Nuclear Information System (INIS)

Carena, M.; Quiros, M.; Wagner, C.E.M.

1998-01-01

It has been recently shown that the observed baryon number may originate at the electroweak phase transition, provided that the Higgs boson and the lightest stop are sufficiently light. In this work, we perform a detailed analysis, including all dominant two-loop finite-temperature corrections to the Higgs effective potential, as well as the non-trivial effects proceeding from the mixing in the stop sector, to define the region of parameter space for which electroweak baryogenesis can happen. The limits on the stop and Higgs masses are obtained by taking into account the experimental bounds on these quantities, as well as those coming from the requirement of avoiding dangerous color breaking minima. We find for the Higgs mass m h < or∼105 GeV, while the stop mass may be close to the present experimental bound and must be smaller than, or of the order of, the top quark mass. These results provide a very strong motivation for further non-perturbative analysis of the electroweak phase transition, as well as for the search for Higgs and stop particles at the LEP and Tevatron colliders. (orig.)

Towards a nonequilibrium quantum field theory approach to electroweak baryogenesis

International Nuclear Information System (INIS)

Riotto, A.

1996-01-01

We propose a general method to compute CP violating observables from extensions of the standard model in the context of electroweak baryogenesis. It is an alternative to the one recently developed by Huet and Nelson and relies on a nonequilibrium quantum field theory approach. The method is valid for all shapes and sizes of the bubble wall expanding in the thermal bath during a first-order electroweak phase transition. The quantum physics of CP violation and its suppression coming from the incoherent nature of thermal processes are also made explicit. copyright 1996 The American Physical Society

Can biological homochirality result from a phase transition?

Science.gov (United States)

Figureau, A; Duval, E; Boukenter, A

1995-06-01

The problem of chiral purity in living organisms is still one of the prominent difficulties in the study of the origins of life. In particular the parity non-conservation known to occur in weak interactions could not be related to this lack of symmetry: these physical forces, though universal, are very weak and up to now no amplification process had been proposed. In 1991, A. Salam remarked that, due to the attractive character of the parity violating force in electro-weak interactions, a phase transition at low temperature should exist, leading eventually to enantiomeric purity. We undertook then a series of experimental tests, looking for a sizeable change in the optical activity of cystine molecules. We found no evidence for the phase transition down to 0.01 K. The interpretation of these negative results will be discussed, and future experiments proposed.

Strong phase transition, dark matter and vacuum stability from simple hidden sectors

Energy Technology Data Exchange (ETDEWEB)

Alanne, Tommi, E-mail: tommi.alanne@jyu.fi [Department of Physics, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 University of Jyväskylä (Finland); Helsinki Institute of Physics, P.O. Box 64, FI-00014 University of Helsinki (Finland); Tuominen, Kimmo, E-mail: kimmo.i.tuominen@helsinki.fi [Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki (Finland); Helsinki Institute of Physics, P.O. Box 64, FI-00014 University of Helsinki (Finland); Vaskonen, Ville, E-mail: ville.vaskonen@jyu.fi [Department of Physics, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 University of Jyväskylä (Finland); Helsinki Institute of Physics, P.O. Box 64, FI-00014 University of Helsinki (Finland)

2014-12-15

Motivated by the possibility to explain dark matter abundance and strong electroweak phase transition, we consider simple extensions of the Standard Model containing singlet fields coupled with the Standard Model via a scalar portal. Concretely, we consider a basic portal model consisting of a singlet scalar with Z{sub 2} symmetry and a model containing a singlet fermion connected with the Standard Model fields via a singlet scalar portal. We perform a Monte Carlo analysis of the parameter space of each model, and we find that in both cases the dark matter abundance can be produced either via freeze-out or freeze-in mechanisms, but only in the latter model one can obtain also a strong electroweak phase transition required by the successful electroweak baryogenesis. We impose the direct search limits and consider systematically the possibility that the model produces only a subdominant portion of the dark matter abundance. We also study the renormalization group evolution of the couplings of the model to determine if the scalar sector of the model remains stable and perturbative up to high scales. With explicit examples of benchmark values of the couplings at weak scale, we show that this is possible. Models of this type are further motivated by the possibility that the excursions of the Higgs field at the end of inflation are large and could directly probe the instability region of the Standard Model.

Acoustic waves and the detectability of first-order phase transitions by eLISA

Science.gov (United States)

Weir, David J.

2017-05-01

In various extensions of the Standard Model it is possible that the electroweak phase transition was first order. This would have been a violent process, involving the formation of bubbles and associated shock waves. Not only would the collision of these bubbles and shock waves be a detectable source of gravitational waves, but persistent acoustic waves could enhance the signal and improve prospects of detection by eLISA. I summarise the results of a recent campaign to model such a phase transition based on large-scale hydrodynamical simulations, and its implications for the eLISA mission.

Split NMSSM with electroweak baryogenesis

Energy Technology Data Exchange (ETDEWEB)

Demidov, S.V.; Gorbunov, D.S. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect 7a, Moscow 117312 (Russian Federation); Moscow Institute of Physics and Technology,Institutsky per. 9, Dolgoprudny 141700 (Russian Federation); Kirpichnikov, D.V. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect 7a, Moscow 117312 (Russian Federation)

2016-11-24

In light of the Higgs boson discovery and other results of the LHC we reconsider 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.

Electroweak form factors

International Nuclear Information System (INIS)

Singh, S.K.

2002-01-01

The present status of electroweak nucleon form factors and the N - Δ transition form factors is reviewed. Particularly the determination of dipole mass M A in the axial vector form factor is discussed

Energy Budget of Cosmological First-order Phase Transitions

CERN Document Server

Espinosa, Jose R; No, Jose M; Servant, Geraldine

2010-01-01

The study of the hydrodynamics of bubble growth in first-order phase transitions is very relevant for electroweak baryogenesis, as the baryon asymmetry depends sensitively on the bubble wall velocity, and also for predicting the size of the gravity wave signal resulting from bubble collisions, which depends on both the bubble wall velocity and the plasma fluid velocity. We perform such study in different bubble expansion regimes, namely deflagrations, detonations, hybrids (steady states) and runaway solutions (accelerating wall), without relying on a specific particle physics model. We compute the efficiency of the transfer of vacuum energy to the bubble wall and the plasma in all regimes. We clarify the condition determining the runaway regime and stress that in most models of strong first-order phase transitions this will modify expectations for the gravity wave signal. Indeed, in this case, most of the kinetic energy is concentrated in the wall and almost no turbulent fluid motions are expected since the s...

Supersymmetric electroweak baryogenesis, nonequilibrium field theory and quantum Boltzmann equations

CERN Document Server

Riotto, Antonio

1998-01-01

The closed time-path (CPT) formalism is a powerful Green's function formulation to describe nonequilibrium phenomena in field theory and it leads to a complete nonequilibrium quantum kinetic theory. In this paper we make use of the CPT formalism to write down a set of quantum Boltzmann equations describing the local number density asymmetries of the particles involved in supersymmetric electroweak baryogenesis. These diffusion equations automatically and self-consistently incorporate the CP-violating sources which fuel baryogenesis when transport properties allow the CP-violating charges to diffuse in front of the bubble wall separating the broken from the unbroken phase at the electroweak phase transition. This is a significant improvement with respect to recent approaches where the CP-violating sources are inserted by hand into the diffusion equations. Furthermore, the CP-violating sources and the particle number changing interactions manifest ``memory'' effects which are typical of the quantum transp ort t...

Gravitational wave generation from bubble collisions in first-order phase transitions: An analytic approach

International Nuclear Information System (INIS)

Caprini, Chiara; Durrer, Ruth; Servant, Geraldine

2008-01-01

Gravitational wave production from bubble collisions was calculated in the early 1990s using numerical simulations. In this paper, we present an alternative analytic estimate, relying on a different treatment of stochasticity. In our approach, we provide a model for the bubble velocity power spectrum, suitable for both detonations and deflagrations. From this, we derive the anisotropic stress and analytically solve the gravitational wave equation. We provide analytical formulas for the peak frequency and the shape of the spectrum which we compare with numerical estimates. In contrast to the previous analysis, we do not work in the envelope approximation. This paper focuses on a particular source of gravitational waves from phase transitions. In a companion article, we will add together the different sources of gravitational wave signals from phase transitions: bubble collisions, turbulence and magnetic fields and discuss the prospects for probing the electroweak phase transition at LISA

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

Energy Technology Data Exchange (ETDEWEB)

Hashino, Katsuya, E-mail: hashino@jodo.sci.u-toyama.ac.jp [Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Kakizaki, Mitsuru, E-mail: kakizaki@sci.u-toyama.ac.jp [Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Kanemura, Shinya, E-mail: kanemu@sci.u-toyama.ac.jp [Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Ko, Pyungwon, E-mail: pko@kias.re.kr [School of Physics, KIAS, Seoul 02455 (Korea, Republic of); Matsui, Toshinori, E-mail: matsui@kias.re.kr [School of Physics, KIAS, Seoul 02455 (Korea, Republic of)

2017-03-10

We calculate the spectrum of gravitational waves originated from strongly first order electroweak phase transition in the extended Higgs model with a real singlet scalar field. In order to calculate the bubble nucleation rate, we perform a two-field analysis and evaluate bounce solutions connecting the true and the false vacua using the one-loop effective potential at finite temperatures. Imposing the Sakharov condition of the departure from thermal equilibrium for baryogenesis, we survey allowed regions of parameters of the model. We then investigate the gravitational waves produced at electroweak bubble collisions in the early Universe, such as the sound wave, the bubble wall collision and the plasma turbulence. We find that the strength at the peak frequency can be large enough to be detected at future space-based gravitational interferometers such as eLISA, DECIGO and BBO. Predicted deviations in the various Higgs boson couplings are also evaluated at the zero temperature, and are shown to be large enough too. Therefore, in this model strongly first order electroweak phase transition can be tested by the combination of the precision study of various Higgs boson couplings at the LHC, the measurement of the triple Higgs boson coupling at future lepton colliders and the shape of the spectrum of gravitational wave detectable at future gravitational interferometers.

Echoes of inflationary first-order phase transitions in the CMB

Energy Technology Data Exchange (ETDEWEB)

Jiang, Hongliang, E-mail: hjiangag@connect.ust.hk [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Special Administrative Region (Hong Kong); Liu, Tao, E-mail: taoliu@ust.hk [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Special Administrative Region (Hong Kong); Sun, Sichun, E-mail: sichun@uw.edu [Jockey Club Institute for Advanced Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Special Administrative Region (Hong Kong); Wang, Yi, E-mail: phyw@ust.hk [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Special Administrative Region (Hong Kong)

2017-02-10

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.

The CP-violating 2HDM in light of a strong first order electroweak phase transition and implications for Higgs pair production

Science.gov (United States)

Basler, P.; Mühlleitner, M.; Wittbrodt, J.

2018-03-01

We investigate the strength of the electroweak phase transition (EWPT) within the CP-violating 2-Higgs-Doublet Model (C2HDM). The 2HDM is a simple and well-studied model, which can feature CP violation at tree level in its extended scalar sector. This makes it, in contrast to the Standard Model (SM), a promising candidate for explaining the baryon asymmetry of the universe through electroweak baryogenesis. We apply a renormalisation scheme which allows efficient scans of the C2HDM parameter space by using the loop-corrected masses and mixing matrix as input parameters. This procedure enables us to investigate the possibility of a strong first order EWPT required for baryogenesis and study its phenomenological implications for the LHC. Like in the CP-conserving (real) 2HDM (R2HDM) we find that a strong EWPT favours mass gaps between the non-SM-like Higgs bosons. These lead to prominent final states comprised of gauge+Higgs bosons or pairs of Higgs bosons. In contrast to the R2HDM, the CP-mixing of the C2HDM also favours approximately mass degenerate spectra with dominant decays into SM particles. The requirement of a strong EWPT further allows us to distinguish the C2HDM from the R2HDM using the signal strengths of the SM-like Higgs boson. We additionally find that a strong EWPT requires an enhancement of the SM-like trilinear Higgs coupling at next-to-leading order (NLO) by up to a factor of 2.4 compared to the NLO SM coupling, establishing another link between cosmology and collider phenomenology. We provide several C2HDM benchmark scenarios compatible with a strong EWPT and all experimental and theoretical constraints. We include the dominant branching ratios of the non-SM-like Higgs bosons as well as the Higgs pair production cross section of the SM-like Higgs boson for every benchmark point. The pair production cross sections can be substantially enhanced compared to the SM and could be observable at the high-luminosity LHC, allowing access to the trilinear

Gravitational wave and collider implications of electroweak baryogenesis aided by non-standard cosmology

International Nuclear Information System (INIS)

Artymowski, Michał; Lewicki, Marek; Wells, James D.

2017-01-01

We consider various models realizing baryogenesis during the electroweak phase transition (EWBG). Our focus is their possible detection in future collider experiments and possible observation of gravitational waves emitted during the phase transition. We also discuss the possibility of a non-standard cosmological history which can facilitate EWBG. We show how acceptable parameter space can be extended due to such a modification and conclude that next generation precision experiments such as the ILC will be able to confirm or falsify many models realizing EWBG. We also show that, in general, collider searches are a more powerful probe than gravitational wave searches. However, observation of a deviation from the SM without any hints of gravitational waves can point to models with modified cosmological history that generically enable EWBG with weaker phase transition and thus, smaller GW signals.

Gravitational wave and collider implications of electroweak baryogenesis aided by non-standard cosmology

Energy Technology Data Exchange (ETDEWEB)

Artymowski, Michał [Jagiellonian University,Łojasiewicza 11, 30-348 Kraków (Poland); Lewicki, Marek [Faculty of Physics, University of Warsaw,ul. Pasteura 5, 02-093 Warsaw (Poland); Michigan Center for Theoretical Physics, University of Michigan,Ann Arbor MI 48109 (United States); Wells, James D. [Michigan Center for Theoretical Physics, University of Michigan,Ann Arbor MI 48109 (United States); Deutsches Elektronen-Synchrotron DESY, Theory Group,D-22603 Hamburg (Germany)

2017-03-13

We consider various models realizing baryogenesis during the electroweak phase transition (EWBG). Our focus is their possible detection in future collider experiments and possible observation of gravitational waves emitted during the phase transition. We also discuss the possibility of a non-standard cosmological history which can facilitate EWBG. We show how acceptable parameter space can be extended due to such a modification and conclude that next generation precision experiments such as the ILC will be able to confirm or falsify many models realizing EWBG. We also show that, in general, collider searches are a more powerful probe than gravitational wave searches. However, observation of a deviation from the SM without any hints of gravitational waves can point to models with modified cosmological history that generically enable EWBG with weaker phase transition and thus, smaller GW signals.

Production of baryon asymmetry of the universe at the electroweak era

Energy Technology Data Exchange (ETDEWEB)

Mallik, S [Saha Inst. of Nuclear Physics, Calcutta (India)

1996-05-01

Author review the elements which enter the calculation of baryon asymmetry at the electroweak scale. We assume the bubble wall created during the phase transition to be sufficiently thin and show that like the (heavy) t quark, the (light) b quark can also produce the observed baryon asymmetry, provided the CP violation within the wall is about two orders of magnitude larger for b quark compared to that for the t quark. (author). 12 refs.

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.

Effective field theory, electric dipole moments and electroweak baryogenesis

International Nuclear Information System (INIS)

Balazs, Csaba; White, Graham; Yue, Jason

2017-01-01

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

Effective field theory, electric dipole moments and electroweak baryogenesis

Energy Technology Data Exchange (ETDEWEB)

Balazs, Csaba; White, Graham [ARC Centre of Excellence for Particle Physics at the Terascale School of Physics and Astronomy,Monash University,Victoria 3800 (Australia); Yue, Jason [Department of Physics, National Taiwan Normal University,Taipei 116, Taiwan (China); ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics,The University of Sydney,NSW 2006 (Australia)

2017-03-07

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

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.)

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.

Electroweak boson production at LHCb

CERN Document Server

Sestini, Lorenzo

2018-01-01

The LHCb experiment offers a complementary phase space to ATLAS and CMS to study electroweak processes, thanks to the forward acceptance and the large bandwidth of the trigger allowing low energy thresholds. For this reason electroweak measurements at LHCb can provide unique constraints to the Parton Distribution Functions. Moreover these measurements can be used to validate reconstruction techniques. In these proceedings the latest measurements on W and Z bosons production performed during the LHC Run I and Run II data taking are presented.

Quantum phase transitions

International Nuclear Information System (INIS)

Sachdev, S.

1999-01-01

Phase transitions are normally associated with changes of temperature but a new type of transition - caused by quantum fluctuations near absolute zero - is possible, and can tell us more about the properties of a wide range of systems in condensed-matter physics. Nature abounds with phase transitions. The boiling and freezing of water are everyday examples of phase transitions, as are more exotic processes such as superconductivity and superfluidity. The universe itself is thought to have passed through several phase transitions as the high-temperature plasma formed by the big bang cooled to form the world as we know it today. Phase transitions are traditionally classified as first or second order. In first-order transitions the two phases co-exist at the transition temperature - e.g. ice and water at 0 deg., or water and steam at 100 deg. In second-order transitions the two phases do not co-exist. In the last decade, attention has focused on phase transitions that are qualitatively different from the examples noted above: these are quantum phase transitions and they occur only at the absolute zero of temperature. The transition takes place at the ''quantum critical'' value of some other parameter such as pressure, composition or magnetic field strength. A quantum phase transition takes place when co-operative ordering of the system disappears, but this loss of order is driven solely by the quantum fluctuations demanded by Heisenberg's uncertainty principle. The physical properties of these quantum fluctuations are quite distinct from those of the thermal fluctuations responsible for traditional, finite-temperature phase transitions. In particular, the quantum system is described by a complex-valued wavefunction, and the dynamics of its phase near the quantum critical point requires novel theories that have no analogue in the traditional framework of phase transitions. In this article the author describes the history of quantum phase transitions. (UK)

Electroweak Physics

OpenAIRE

Erler, Jens; Langacker, Paul

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.

Electroweak penguin diagrams and two-body B decays

International Nuclear Information System (INIS)

Gronau, M.; Hernandez, O.F.; London, D.; Rosner, J.L.

1995-01-01

We discuss the role of electroweak penguin diagrams in B decays to two light pseudoscalar mesons. We confirm that the extraction of the weak phase α through the isospin analysis involving B→ππ decays is largely unaffected by such operators. However, the methods proposed to obtain weak and strong phases by relating B→ππ, B→πK, and B→K bar K decays through flavor SU(3) will be invalidated if eletroweak penguin diagrams are large. We show that, although the introduction of electroweak penguin contributions introduces no new amplitudes of flavor SU(3), there are a number of ways to experimentally measure the size of such effects. Finally, using SU(3) amplitude relations we present a new way of measuring the weak angle γ which holds even in the presence of electroweak penguin diagrams

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].

Baryogenesis at the electroweak scale

International Nuclear Information System (INIS)

Dine, M.; Huet, P.; Singleton, R. Jr.

1992-01-01

We explore some issues involved in generating the baryon asymmetry at the electroweak scale. A simple two-dimensional model is analyzed which illustrates the role of the effective action in computing the asymmetry. We stress the fact that baryon production ceases at a very small value of the Higgs field; as a result, certain two-Higgs models which have been studied recently cannot produce sufficient asymmetry, while quite generally models with only doublets can barely produce the observed baryon density; models with gauge singlets are more promising. We also review limits on Higgs masses coming from the requirement that the baryon asymmetry not be wiped out after the phase transition. We note that there are a variety of uncertainties in these calculations, and that even in models with a single Higgs doublet one cannot rule out a Higgs mass below 55 GeV. (orig.)

Eigenstate Phase Transitions

Science.gov (United States)

Zhao, Bo

Phase transitions are one of the most exciting physical phenomena ever discovered. The understanding of phase transitions has long been of interest. Recently eigenstate phase transitions have been discovered and studied; they are drastically different from traditional thermal phase transitions. In eigenstate phase transitions, a sharp change is exhibited in properties of the many-body eigenstates of the Hamiltonian of a quantum system, but not the thermal equilibrium properties of the same system. In this thesis, we study two different types of eigenstate phase transitions. The first is the eigenstate phase transition within the ferromagnetic phase of an infinite-range spin model. By studying the interplay of the eigenstate thermalization hypothesis and Ising symmetry breaking, we find two eigenstate phase transitions within the ferromagnetic phase: In the lowest-temperature phase the magnetization can macroscopically oscillate by quantum tunneling between up and down. The relaxation of the magnetization is always overdamped in the remainder of the ferromagnetic phase, which is further divided into phases where the system thermally activates itself over the barrier between the up and down states, and where it quantum tunnels. The second is the many-body localization phase transition. The eigenstates on one side of the transition obey the eigenstate thermalization hypothesis; the eigenstates on the other side are many-body localized, and thus thermal equilibrium need not be achieved for an initial state even after evolving for an arbitrary long time. We study this many-body localization phase transition in the strong disorder renormalization group framework. After setting up a set of coarse-graining rules for a general one dimensional chain, we get a simple "toy model'' and obtain an almost purely analytical solution to the infinite-randomness critical fixed point renormalization group equation. We also get an estimate of the correlation length critical exponent nu

Enhancement of neutral tc transitions in the model of dynamical breaking of electroweak symmetry

International Nuclear Information System (INIS)

Arbuzov, B.A.; Osipov, M.Yu.

1999-01-01

The problem of possible deviations from the standard model is considered in the framework of a variant of dynamical electroweak symmetry breaking. It comes clear, that the parameters of the theory, being obtained earlier and describing deviations from standard model in Z → b-barb decay, are also consistent with the existence of a nontrivial solution for vertex t-bar (Z, γ)c. The occurrence of this solution leads to a significant enhancement in neutral flavor changing transition t → c. The intensity of this transition is connected with the c-quark mass, that leads to estimates of probabilities of exotic decays t → c(Z, γ) and of the cross section of a single t-quark production in process e + e - → tc-bar, which threshold is already overcome at LEP2. The model is shown to be consistent with the totality of the existing data, the predictions allow its unambiguous check [ru

Exclusive radiative and electroweak b→d and b→s penguin decays at NLO

International Nuclear Information System (INIS)

Beneke, M.; Seidel, D.; Feldmann, T.

2005-01-01

We provide standard model expectations for the rare radiative decays B→K * γ, B→ργ and B→ωγ, and the electroweak penguin decays B→K * l + l - and B→ρl + l - at the next-to-leading order (NLO), extending our previous results to b→d transitions. We consider branching fractions, isospin asymmetries and direct CPasymmetries. For the electroweak penguin decays, the lepton-invariant mass spectrum and forward-backward asymmetry is also included. Radiative and electroweak penguin transitions in b→d are mainly interesting in the search for new flavor-changing neutral current interactions, but in addition the B→ργ decays provide constraints on the CKM parameters (anti ρ, anti η). The potential impact of these constraints is discussed. (orig.)

String phase transitions in a strong magnetic field

CERN Document Server

Ferrara, Sergio; Ferrara, Sergio; Porrati, Massimo

1993-01-01

We consider open strings in an external constant magnetic field $H$. For an (infinite) sequence of critical values of $H$ an increasing number of (highest spin component) states lying on the first Regge trajectory becomes tachyonic. In the limit of infinite $H$ all these states are tachyons (with a common tachyonic mass) both in the case of the bosonic string and for the Neveu-Schwarz sector of the fermionic string. This result generalizes to extended object the same instability which occurs in ordinary non-Abelian gauge theories. The Ramond states have always positive square masses as is the case for ordinary QED. The weak field limit of the mass spectrum is the same as for a field theory with gyromagnetic ratio $g_S=2$ for all charged spin states. This behavior suggests a phase transition of the string as it has been argued for the ordinary electroweak theory.

Phase transitions

CERN Document Server

Sole, Ricard V; Solé, Ricard V; Solé, Ricard V; Sol, Ricard V; Solé, Ricard V

2011-01-01

Phase transitions--changes between different states of organization in a complex system--have long helped to explain physics concepts, such as why water freezes into a solid or boils to become a gas. How might phase transitions shed light on important problems in biological and ecological complex systems? Exploring the origins and implications of sudden changes in nature and society, Phase Transitions examines different dynamical behaviors in a broad range of complex systems. Using a compelling set of examples, from gene networks and ant colonies to human language and the degradation of diverse ecosystems, the book illustrates the power of simple models to reveal how phase transitions occur. Introductory chapters provide the critical concepts and the simplest mathematical techniques required to study phase transitions. In a series of example-driven chapters, Ricard Solé shows how such concepts and techniques can be applied to the analysis and prediction of complex system behavior, including the origins of ...

Lepton-mediated electroweak baryogenesis

International Nuclear Information System (INIS)

Chung, Daniel J. H.; Garbrecht, Bjorn; Ramsey-Musolf, Michael J.; Tulin, Sean

2010-01-01

We investigate the impact of the tau and bottom Yukawa couplings on the transport dynamics for electroweak baryogenesis in supersymmetric extensions of the standard model. Although it has generally been assumed in the literature that all Yukawa interactions except those involving the top quark are negligible, we find that the tau and bottom Yukawa interaction rates are too fast to be neglected. We identify an illustrative 'lepton-mediated electroweak baryogenesis' scenario in which the baryon asymmetry is induced mainly through the presence of a left-handed leptonic charge. We derive analytic formulas for the computation of the baryon asymmetry that, in light of these effects, are qualitatively different from those in the established literature. In this scenario, for fixed CP-violating phases, the baryon asymmetry has opposite sign compared to that calculated using established formulas.

Cosmological QCD phase transition in steady non-equilibrium dissipative Hořava–Lifshitz early universe

International Nuclear Information System (INIS)

Khodadi, M.; Sepangi, H.R.

2014-01-01

We study the phase transition from quark–gluon plasma to hadrons in the early universe in the context of non-equilibrium thermodynamics. According to the standard model of cosmology, a phase transition associated with chiral symmetry breaking after the electro-weak transition has occurred when the universe was about 1–10 μs old. We focus attention on such a phase transition in the presence of a viscous relativistic cosmological background fluid in the framework of non-detailed balance Hořava–Lifshitz cosmology within an effective model of QCD. We consider a flat Friedmann–Robertson–Walker universe filled with a non-causal and a causal bulk viscous cosmological fluid respectively and investigate the effects of the running coupling constants of Hořava–Lifshitz gravity, λ, on the evolution of the physical quantities relevant to a description of the early universe, namely, the temperature T, scale factor a, deceleration parameter q and dimensionless ratio of the bulk viscosity coefficient to entropy density (ξ)/s . We assume that the bulk viscosity cosmological background fluid obeys the evolution equation of the steady truncated (Eckart) and full version of the Israel–Stewart fluid, respectively. -- Highlights: •In this paper we have studied quark–hadron phase transition in the early universe in the context of the Hořava–Lifshitz model. •We use a flat FRW universe with the bulk viscosity cosmological background fluid obeying the evolution equation of the steady truncated (Eckart) and full version of the Israel–Stewart fluid, respectively

Tricritical point in quantum phase transitions of the Coleman–Weinberg model at Higgs mass

International Nuclear Information System (INIS)

Fiolhais, Miguel C.N.; Kleinert, Hagen

2013-01-01

The tricritical point, which separates first and second order phase transitions in three-dimensional superconductors, is studied in the four-dimensional Coleman–Weinberg model, and the similarities as well as the differences with respect to the three-dimensional result are exhibited. The position of the tricritical point in the Coleman–Weinberg model is derived and found to be in agreement with the Thomas–Fermi approximation in the three-dimensional Ginzburg–Landau theory. From this we deduce a special role of the tricritical point for the Standard Model Higgs sector in the scope of the latest experimental results, which suggests the unexpected relevance of tricritical behavior in the electroweak interactions.

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

International Nuclear Information System (INIS)

Chala, Mikael; Nardini, Germano; Sobolev, Ivan; Moscow State Univ.

2016-05-01

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 matter direct detection and gravitational wave experiments.

Semiclassical force for electroweak baryogenesis three-dimensional derivation

CERN Document Server

Kainulainen, K; Schmidt, M G; Weinstock, S; Kainulainen, Kimmo; Prokopec, Tomislav; Schmidt, Michael G.; Weinstock, Steffen

2002-01-01

We derive a semiclassical transport equation for fermions propagating in the presence of a CP-violating planar bubble wall at a first order electroweak phase transition. Starting from the Kadanoff-Baym (KB) equation for the two-point (Wightman) function we perform an expansion in gradients, or equivalently in the Planck constant h-bar. We show that to first order in h-bar the KB equations have a spectral solution, which allows for an on-shell description of the plasma excitations. The CP-violating force acting on these excitations is found to be enhanced by a boost factor in comparison with the 1+1-dimensional case studied in a former paper. We find that an identical semiclassical force can be obtained by the WKB method. Applications to the MSSM are also mentioned.

Cosmological phase transitions

International Nuclear Information System (INIS)

Kolb, E.W.

1987-01-01

If the universe stated from conditions of high temperature and density, there should have been a series of phase transitions associated with spontaneous symmetry breaking. The cosmological phase transitions could have observable consequences in the present Universe. Some of the consequences including the formation of topological defects and cosmological inflation are reviewed here. One of the most important tools in building particle physics models is the use of spontaneous symmetry breaking (SSB). The proposal that there are underlying symmetries of nature that are not manifest in the vacuum is a crucial link in the unification of forces. Of particular interest for cosmology is the expectation that are the high temperatures of the big bang symmetries broken today will be restored, and that there are phase transitions to the broken state. The possibility that topological defects will be produced in the transition is the subject of this section. The possibility that the Universe will undergo inflation in a phase transition will be the subject of the next section. Before discussing the creation of topological defects in the phase transition, some general aspects of high-temperature restoration of symmetry and the development of the phase transition will be reviewed. 29 references, 1 figure, 1 table

Gauge invariant treatment of the electroweak phase transition

International Nuclear Information System (INIS)

Buchmueller, W.; Fodor, Z.; Hebecker, A.

1994-03-01

We evaluate the gauge invariant effective potential for the composite field σ = 2Φ † Φin the SU(2)-Higgs model at finite temperature. Symmetric and broken phases correspond to the domains σ ≤ T 2 /3 and σ > T 2 /3, respectively. The effective potential increases very steeply at small values of σ. Predictions for several observables, derived from the ordinary and the gauge invariant effective potential, are compared. Good agreement is found for the critical temperature and the jump in the order parameter. The results for the latent heat differ significantly for large Higgs masses. (orig.)

Fundamental Physics with Electroweak Probes of Nuclei

Science.gov (United States)

Pastore, Saori

2018-02-01

The past decade has witnessed tremendous progress in the theoretical and computational tools that produce our understanding of nuclei. A number of microscopic calculations of nuclear electroweak structure and reactions have successfully explained the available experimental data, yielding a complex picture of the way nuclei interact with electroweak probes. This achievement is of great interest from the pure nuclear-physics point of view. But it is of much broader interest too, because the level of accuracy and confidence reached by these calculations opens up the concrete possibility of using nuclei to address open questions in other sub-fields of physics, such as, understanding the fundamental properties of neutrinos, or the particle nature of dark matter. In this talk, I will review recent progress in microscopic calculations of electroweak properties of light nuclei, including electromagnetic moments, form factors and transitions in between lowlying nuclear states along with preliminary studies for single- and double-beta decay rates. I will illustrate the key dynamical features required to explain the available experimental data, and, if time permits, present a novel framework to calculate neutrino-nucleus cross sections for A > 12 nuclei.

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

International Nuclear Information System (INIS)

Sagunski, Laura

2013-04-01

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 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) L x SU(2) R x U(1) 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 o 2 Ω GW ≅ 3 . 10 -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 α and β of the gravitational wave spectrum, we finally compute the lower bounds on α(T * ) in dependence of the tunneling temperature T * which are necessary for a detection of the model spectrum by the specific detectors.

Detectable gravitational waves from very strong phase transitions in the general NMSSM

International Nuclear Information System (INIS)

Huber, Stephan J.; Nardini, Germano; Bern Univ.

2015-12-01

We study the general NMSSM with an emphasis on the parameter regions with a very strong first-order electroweak phase transition (EWPT). In the presence of heavy fields coupled to the Higgs sector, the analysis can be problematic due to the existence of sizable radiative corrections. In this paper we propose a subtraction scheme that helps to circumvent this problem. For simplicity we focus on a parameter region that is by construction hidden from the current collider searches. The analysis proves that (at least) in the identified parameter region the EWPT can be very strong and striking gravitational wave signals can be produced. The corresponding gravitational stochastic background can potentially be detected at the planned space-based gravitational wave observatory eLISA, depending on the specific experiment design that will be approved.

Electroweak penguin contributions in charmless B→VV decays beyond leading logarithms

International Nuclear Information System (INIS)

Dongsheng Du; Libo Guo

1997-01-01

Using the next-to-leading-order, low-energy effective Hamiltonian for vertical bar ΔB vertical bar = 1, ΔC = ΔU = 0 transitions, the contributions of electroweak penguin operators in charmless B→VV decays are estimated in the standard model. We find that, for some channels, the electroweak penguin effects can enhance or reduce the QCD penguin and/or tree-level contributions by at least 20%, and can even play a dominant role in decay widths and CP-asymmetries, but the corrections to the angular distribution are negligible. (author)

Electroweak Results from CMS

CERN Multimedia

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.

The electroweak theory

International Nuclear Information System (INIS)

Chris Quigg

2001-01-01

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) L (circle-times) U(1) 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

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.

Unanswered Questions in the Electroweak Theory

International Nuclear Information System (INIS)

Quigg, Chris

2009-01-01

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.

Electroweak form factors of the Skyrmion

International Nuclear Information System (INIS)

Braaten, E.; Sze-Man Tse; Willcox, C.

1986-01-01

The electroweak form factors of baryons are studied in the semiclassical approximation to the Skyrme model. General expressions for the form factors are given for arbitrary choices of the Skyrme-model Lagrangian. They are applied to the original two-parameter Skyrme model to compute the electric, magnetic, and axial-vector form factors of the nucleon and the electromagnetic nucleon-Δ transition form factors. The dependence of the form factors on the momentum transfer is compared with phenomenological dipole parametrizations

Precision electroweak measurements

International Nuclear Information System (INIS)

Demarteau, M.

1996-11-01

Recent electroweak precision measurements fro e + e - and p anti p colliders are presented. Some emphasis is placed on the recent developments in the heavy flavor sector. The measurements are compared to predictions from the Standard Model of electroweak interactions. All results are found to be consistent with the Standard Model. The indirect constraint on the top quark mass from all measurements is in excellent agreement with the direct m t measurements. Using the world's electroweak data in conjunction with the current measurement of the top quark mass, the constraints on the Higgs' mass are discussed

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.

Martensitic phase transitions

International Nuclear Information System (INIS)

Petry, W.; Neuhaus, J.

1996-01-01

Many elements transform from a high temperature bcc phase to a more dense packed temperature phase. The great majority of these transitions are of 1st order, displacive and reconstructive. The lattice potentials which govern these martensitic transitions can be probed by inelastic neutron scattering, thereby answering fundamental questions like : Will the transition be announced by dynamical or static fluctuations? What are the trajectories for the displacements needed for the transformation? Does the vibrational entropy stabilize the high temperature phase? Are the unusual transport properties in these materials related to their ability to transform? (author) 17 figs., 1 tab., 46 refs

Martensitic phase transitions

Energy Technology Data Exchange (ETDEWEB)

Petry, W; Neuhaus, J [Techn. Universitaet Muenchen, Physik Department E13, Munich (Germany)

1996-11-01

Many elements transform from a high temperature bcc phase to a more dense packed temperature phase. The great majority of these transitions are of 1st order, displacive and reconstructive. The lattice potentials which govern these martensitic transitions can be probed by inelastic neutron scattering, thereby answering fundamental questions like : Will the transition be announced by dynamical or static fluctuations? What are the trajectories for the displacements needed for the transformation? Does the vibrational entropy stabilize the high temperature phase? Are the unusual transport properties in these materials related to their ability to transform? (author) 17 figs., 1 tab., 46 refs.

Phase transitions in nuclear physics

Energy Technology Data Exchange (ETDEWEB)

Moretto, L.G.; Phair, L.; Wozniak, G.J.

1997-08-01

A critical overview of the low energy phase transitions in nuclei is presented with particular attention to the 2nd (1st) order pairing phase transitions, and to the 1st order liquid-vapor phase transition. The role of fluctuations in washing out these transitions is discussed and illustrated with examples. A robust indicator of phase coexistence in multifragmentation is presented.

Phase transitions in nuclear physics

International Nuclear Information System (INIS)

Moretto, L.G.; Phair, L.; Wozniak, G.J.

1997-08-01

A critical overview of the low energy phase transitions in nuclei is presented with particular attention to the 2nd (1st) order pairing phase transitions, and to the 1st order liquid-vapor phase transition. The role of fluctuations in washing out these transitions is discussed and illustrated with examples. A robust indicator of phase coexistence in multifragmentation is presented

Thermodynamics of phase transitions

International Nuclear Information System (INIS)

Cofta, H.

1972-01-01

The phenomenology of the phase transitions has been considered. The definitions of thermodynamic functions and parameters, as well as those of the phase transitions, are given and some of the relations between those quantities are discussed. The phase transitions classification proposed by Ehrenfest has been described. The most important features of phase transitions are discussed using the selected physical examples including the critical behaviour of ferromagnetic materials at the Curie temperature and antiferromagnetic materials at the Neel temperature. Some aspects of the Ehrenfest's equations, that have been derived, for the interfacial lines and surfaces are considered as well as the role the notion of interfaces. (S.B.)

Electroweak Physics

OpenAIRE

Hollik, W.

2005-01-01

The status of precision electroweak measurements as of summer 2002 is reviewed. The recent results on the anomalous magnetic moment of the muon and on neutrino-nucleon scattering are discussed. Precision results on the electroweak interaction obtained by the experiments at the SLC, LEP and TEVATRON colliders are presented. The experimental results are compared with the predictions of the minimal Standard Model and are used to constrain its parameters, including the mass of the Higgs boson. Th...

State of electroweak interactions

International Nuclear Information System (INIS)

Lane, K.

1984-01-01

I assess what we know and what we do not know about the electroweak interactions. In particular, I argue that existing data on the electroweak parameters rho, sin 2 theta/sub w/ and G/sub F/ and on the recently discovered W +- and Z 0 allow us reasonably to conclude that: (1) the W +- and Z 0 truly are the elementary massive gauge bosons of SU(2) x U(1) and not the composite bosons of a new strong interaction, and (2) the electroweak scalar sector consists of weak doublets only. The most important thing we do not know is everything else about the electroweak scalar sector. In the hope of soon shedding light on this issue, a new method of searching for electroweak scalars in existing p-barp colliders is proposed. The basis of this method is that the branching ratio of W +- to decay to a charged plus a neutral scalar (expected in non-minimal SU(2) x U(1) models) can be as large as 1-2%, with detectable rates up to scalar masses of approx.35 GeV

Phase transitions modern applications

CERN Document Server

Gitterman, Moshe

2014-01-01

This book provides a comprehensive review of the theory of phase transitions and its modern applications, based on the five pillars of the modern theory of phase transitions i.e. the Ising model, mean field, scaling, renormalization group and universality. This expanded second edition includes, along with a description of vortices and high temperature superconductivity, a discussion of phase transitions in chemical reaction and moving systems. The book covers a close connection between phase transitions and small world phenomena as well as scale-free systems such as the stock market and the Internet. Readership: Scientists working in different fields of physics, chemistry, biology and economics as well as teaching material for undergraduate and graduate courses.

Phase transitions in surfactant monolayers

International Nuclear Information System (INIS)

Casson, B.D.

1998-01-01

Two-dimensional phase transitions have been studied in surfactant monolayers at the air/water interface by sum-frequency spectroscopy and ellipsometry. In equilibrium monolayers of medium-chain alcohols C n H 2n+1 OH (n = 9-14) a transition from a two-dimensional crystalline phase to a liquid was observed at temperatures above the bulk melting point. The small population of gauche defects in the solid phase increased only slightly at the phase transition. A model of the hydrocarbon chains as freely rotating rigid rods allowed the area per molecule and chain tilt in the liquid phase to be determined. The area per molecule, chain tilt and density of the liquid phase all increased with increasing chain length, but for each chain length the density was higher than in a bulk liquid hydrocarbon. In a monolayer of decanol adsorbed at the air/water interface a transition from a two-dimensional liquid to a gas was observed. A clear discontinuity in the coefficient of ellipticity as a function of temperature showed that the transition is first-order. This result suggests that liquid-gas phase transitions in surfactant monolayers may be more widespread than once thought. A solid-liquid phase transition has also been studied in mixed monolayers of dodecanol with an anionic surfactant (sodium dodecyl sulphate) and with a homologous series of cationic surfactants (alkyltrimethylammonium bromides: C n TABs, n = 12, 14, 16). The composition and structure of the mixed monolayers was studied above and below the phase transition. At low temperatures the mixed monolayers were as densely packed as a monolayer of pure dodecanol in its solid phase. At a fixed temperature the monolayers under-went a first-order phase transition to form a phase that was less dense and more conformationally disordered. The proportion of ionic surfactant in the mixed monolayer was greatest in the high temperature phase. As the chain length of the C n TAB increased the number of conformational defects

Li-ion batteries: Phase transition

International Nuclear Information System (INIS)

Hou Peiyu; Zhang Yantao; Zhang Lianqi; Chu Geng; Gao Jian

2016-01-01

Progress in the research on phase transitions during Li + extraction/insertion processes in typical battery materials is summarized as examples to illustrate the significance of understanding phase transition phenomena in Li-ion batteries. Physical phenomena such as phase transitions (and resultant phase diagrams) are often observed in Li-ion battery research and already play an important role in promoting Li-ion battery technology. For example, the phase transitions during Li + insertion/extraction are highly relevant to the thermodynamics and kinetics of Li-ion batteries, and even physical characteristics such as specific energy, power density, volume variation, and safety-related properties. (topical review)

Electroweak baryogenesis

International Nuclear Information System (INIS)

Trodden, Mark

1999-01-01

Contrary to naive cosmological expectations, all evidence suggests that the universe contains an abundance of matter over antimatter. This article reviews the currently popular scenario in which testable physics, present in the standard model of electroweak interactions and its modest extensions, is responsible for this fundamental cosmological datum. A pedagogical explanation of the motivations and physics behind electroweak baryogenesis is provided, and analytical approaches, numerical studies, up to date developments, and open questions in the field are also discussed. (c) 1999 The American Physical Society

Symmetry and Phase Transitions in Nuclei

International Nuclear Information System (INIS)

Iachello, F.

2009-01-01

Phase transitions in nuclei have received considerable attention in recent years, especially after the discovery that, contrary to expectations, systems at the critical point of a phase transition display a simple structure. In this talk, quantum phase transitions (QPT), i.e. phase transitions that occur as a function of a coupling constant that appears in the quantum Hamiltonian, H, describing the system, will be reviewed and experimental evidence for their occurrence in nuclei will be presented. The phase transitions discussed in the talk will be shape phase transitions. Different shapes have different symmetries, classified by the dynamic symmetries of the Interacting Boson Model, U(5), SU(3) and SO(6). Very recently, the concept of Quantum Phase Transitions has been extended to Excited State Quantum Phase Transitions (ESQPT). This extension will be discussed and some evidence for incipient ESQPT in nuclei will be presented. Systems at the critical point of a phase transition are called 'critical systems'. Approximate analytic formulas for energy spectra and other properties of 'critical nuclei', in particular for nuclei at the critical point of the second order U(5)-SO(6) transition, called E(5), and along the line of first order U(5)-SU(3) transitions, called X(5), will be presented. Experimental evidence for 'critical nuclei' will be also shown. Finally, the microscopic derivation of shape phase transitions in nuclei within the framework of density functional methods will be briefly discussed.(author)

Non-equilibrium phase transitions

CERN Document Server

Henkel, Malte; Lübeck, Sven

2009-01-01

This book describes two main classes of non-equilibrium phase-transitions: (a) static and dynamics of transitions into an absorbing state, and (b) dynamical scaling in far-from-equilibrium relaxation behaviour and ageing. The first volume begins with an introductory chapter which recalls the main concepts of phase-transitions, set for the convenience of the reader in an equilibrium context. The extension to non-equilibrium systems is made by using directed percolation as the main paradigm of absorbing phase transitions and in view of the richness of the known results an entire chapter is devoted to it, including a discussion of recent experimental results. Scaling theories and a large set of both numerical and analytical methods for the study of non-equilibrium phase transitions are thoroughly discussed. The techniques used for directed percolation are then extended to other universality classes and many important results on model parameters are provided for easy reference.

Phase transition in finite systems

International Nuclear Information System (INIS)

Chomaz, Ph.; Duflot, V.; Duflot, V.; Gulminelli, F.

2000-01-01

In this paper we present a review of selected aspects of Phase transitions in finite systems applied in particular to the liquid-gas phase transition in nuclei. We show that the problem of the non existence of boundary conditions can be solved by introducing a statistical ensemble with an averaged constrained volume. In such an ensemble the microcanonical heat capacity becomes negative in the transition region. We show that the caloric curve explicitly depends on the considered transformation of the volume with the excitation energy and so does not bear direct informations on the characteristics of the phase transition. Conversely, partial energy fluctuations are demonstrated to be a direct measure of the equation of state. Since the heat capacity has a negative branch in the phase transition region, the presence of abnormally large kinetic energy fluctuations is a signal of the liquid gas phase transition. (author)

Semilocal and electroweak strings

NARCIS (Netherlands)

Achucarro, A; Vachaspati, T

We review a class of non-topological defects in the standard electroweak model, and their implications. Starting with the semilocal string, which provides a counterexample to many well-known properties of topological vortices, we discuss electroweak strings and their stability with and without

Electroweak and strong penguins in B±,0 →ππ,πK and KK decays

International Nuclear Information System (INIS)

Kramer, G.; Palmer, W.F.

1995-01-01

We calculate CP-violating rates and asymmetry parameters in charged and neutral B→ππ, πK and anti KK decays arising from the interference of tree and penguin (strong and electroweak) amplitudes with different strong and CKM phases. The perturbative strong (electroweak) phases develop at order α s (α em ) from absorptive parts of one-loop matrix elements of the next-to-leading (leading) logarithm corrected effective Hamiltonian. The BSW model is used to estimate the hadronic matrix elements. Based on this model, we find that the effect of strong phases and penguins is substantial in most channels, drastic in many. However, a measurement of the time dependence parameter α ε+ε' in the π + π - channel is only influenced at the 20% level by the complication of the penguins. Recent flavor sum rules developed for B 0,± →ππ, πK, K anti K amplitudes are tested in this model. Some are well satisfied, others badly violated, when electroweak penguins are included. (orig.)

The nuclear liquid gas phase transition and phase coexistence

International Nuclear Information System (INIS)

Chomaz, Ph.

2001-01-01

In this talk we will review the different signals of liquid gas phase transition in nuclei. From the theoretical side we will first discuss the foundations of the concept of equilibrium, phase transition and critical behaviors in infinite and finite systems. From the experimental point of view we will first recall the evidences for some strong modification of the behavior of hot nuclei. Then we will review quantitative detailed analysis aiming to evidence phase transition, to define its order and phase diagram. Finally, we will present a critical discussion of the present status of phase transitions in nuclei and we will draw some lines for future development of this field. (author)

The nuclear liquid gas phase transition and phase coexistence

Energy Technology Data Exchange (ETDEWEB)

Chomaz, Ph

2001-07-01

In this talk we will review the different signals of liquid gas phase transition in nuclei. From the theoretical side we will first discuss the foundations of the concept of equilibrium, phase transition and critical behaviors in infinite and finite systems. From the experimental point of view we will first recall the evidences for some strong modification of the behavior of hot nuclei. Then we will review quantitative detailed analysis aiming to evidence phase transition, to define its order and phase diagram. Finally, we will present a critical discussion of the present status of phase transitions in nuclei and we will draw some lines for future development of this field. (author)

Electroweak evolution equations

International Nuclear Information System (INIS)

Ciafaloni, Paolo; Comelli, Denis

2005-01-01

Enlarging a previous analysis, where only fermions and transverse gauge bosons were taken into account, we write down infrared-collinear evolution equations for the Standard Model of electroweak interactions computing the full set of splitting functions. Due to the presence of double logs which are characteristic of electroweak interactions (Bloch-Nordsieck violation), new infrared singular splitting functions have to be introduced. We also include corrections related to the third generation Yukawa couplings

Magnetic resonance of phase transitions

CERN Document Server

Owens, Frank J; Farach, Horacio A

1979-01-01

Magnetic Resonance of Phase Transitions shows how the effects of phase transitions are manifested in the magnetic resonance data. The book discusses the basic concepts of structural phase and magnetic resonance; various types of magnetic resonances and their underlying principles; and the radiofrequency methods of nuclear magnetic resonance. The text also describes quadrupole methods; the microwave technique of electron spin resonance; and the Mössbauer effect. Phase transitions in various systems such as fluids, liquid crystals, and crystals, including paramagnets and ferroelectrics, are also

The end point of the first-order phase transition of the SU(2) gauge-Higgs model on a four-dimensional isotropic lattice

International Nuclear Information System (INIS)

Aoki, Y.; Csikor, F.; Fodor, Z.; Ukawa, A.

1999-01-01

We report results of a study of the end point of the electroweak phase transition of the SU(2) gauge-Higgs model defined on a four-dimensional isotropic lattice with N t = 2. Finite-size scaling study of Lee-Yang zeros yields λ c = 0.00116(16) for the end point. Combined with a zero-temperature measurement of Higgs and W boson masses, this leads to M H,c = 68.2 ± 6.6 GeV for the critical Higgs boson mass. An independent analysis of Binder cumulant gives a consistent value λ c = 0.00102(3) for the end point

Signatures of CP-Violating Electroweak Penguins in K and B Decays

International Nuclear Information System (INIS)

Schwab, Felix

2007-01-01

The B->πK decays with significant electroweak penguin contributions show a puzzling pattern. We explore this ''B->πK puzzle'' through a systematic strategy. The starting point, which is essentially unaffected by electroweak penguins, is the determination of the angle γ of the unitarity triangle through the CP-violating B d 0 ->π + π - , B d 0 ->π - K + asymmetries, yielding γ=(73.9 -6.5 +5.8 ) o , and the extraction of hadronic parameters through the measured B->ππ branching ratios. Using arguments related to the SU(3) flavor symmetry, we convert the hadronic B->ππ parameters into their B->πK counterparts, allowing us to predict the B->πK observables in the Standard Model. We find agreement with the data for those quantities that are only marginally affected by electroweak penguins, while this is not the case for the observables with sizeable electroweak penguin contributions. Since we may also perform a couple of internal consistency checks of our working assumptions, which are nicely satisfied for the current data, and find a small sensitivity of our results to large non-factorizable SU(3)-breaking corrections, the ''B->πK'' puzzle may be due to new physics in the electroweak penguin sector. We show that it can indeed be resolved through such a kind of new physics with a large CP-violating phase. Further insights into the electroweak penguins are provided by the B + ->π 0 K + and B d 0 ->π 0 K S CP asymmetries, and in particular through correlations with various rare K and B decays

Next-to-leading-order QCD and electroweak corrections to WWW production at proton-proton colliders

Science.gov (United States)

Dittmaier, Stefan; Huss, Alexander; Knippen, Gernot

2017-09-01

Triple-W-boson production in proton-proton collisions allows for a direct access to the triple and quartic gauge couplings and provides a window to the mechanism of electroweak symmetry breaking. It is an important process to test the Standard Model (SM) and might be background to physics beyond the SM. We present a calculation of the next-to-leading order (NLO) electroweak corrections to the production of WWW final states at proton-proton colliders with on-shell W bosons and combine the electroweak with the NLO QCD corrections. We study the impact of the corrections to the integrated cross sections and to kinematic distributions of the W bosons. The electroweak corrections are generically of the size of 5-10% for integrated cross sections and become more pronounced in specific phase-space regions. The real corrections induced by quark-photon scattering turn out to be as important as electroweak loops and photon bremsstrahlung corrections, but can be reduced by phase-space cuts. Considering that prior determinations of the photon parton distribution function (PDF) involve rather large uncertainties, we compare the results obtained with different photon PDFs and discuss the corresponding uncertainties in the NLO predictions. Moreover, we determine the scale and total PDF uncertainties at the LHC and a possible future 100 TeV pp collider.

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.)

Electroweak interactions in nuclei

International Nuclear Information System (INIS)

Henley, E.M.

1984-06-01

Topics include: introduction to electroweak theory; the Weinberg-Salam theory for leptons; the Weinberg-Salam theory for hadrons-the GIM mechanism; electron scattering as a probe of the electroweak interaction (observation of PV, the weak interaction for nucleons, and parity violation in atoms); and time reversed invariance and electric dipole moments of nucleons, nuclei, and atoms. 52 references

Gravitationally coupled electroweak monopole

Energy Technology Data Exchange (ETDEWEB)

Cho, Y.M., E-mail: ymcho7@konkuk.ac.kr [Administration Building 310-4, Konkuk University, Seoul 143-701 (Korea, Republic of); School of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Kimm, Kyoungtae [Faculty of Liberal Education, Seoul National University, Seoul 151-747 (Korea, Republic of); Yoon, J.H. [Department of Physics, College of Natural Sciences, Konkuk University, Seoul 143-701 (Korea, Republic of)

2016-10-10

We present a family of gravitationally coupled electroweak monopole solutions in Einstein–Weinberg–Salam theory. Our result confirms the existence of globally regular gravitating electroweak monopole which changes to the magnetically charged black hole as the Higgs vacuum value approaches to the Planck scale. Moreover, our solutions could provide a more accurate description of the monopole stars and magnetically charged black holes.

Electronic phase transitions

CERN Document Server

Kopaev, YuV

1992-01-01

Electronic Phase Transitions deals with topics, which are presently at the forefront of scientific research in modern solid-state theory. Anderson localization, which has fundamental implications in many areas of solid-state physics as well as spin glasses, with its influence on quite different research activities such as neural networks, are two examples that are reviewed in this book. The ab initio statistical mechanics of structural phase transitions is another prime example, where the interplay and connection of two unrelated disciplines of solid-state theory - first principle ele

Electroweak Physics at the LHC

CERN Document Server

Sommer, Philip; The ATLAS collaboration

2018-01-01

With the large integrated luminosities recorded at the LHC and the excellent understanding of the LHC detectors, it is possible to measure electroweak observables to the highest precision. A review of the measurement of the $W$ boson mass by the ATLAS Collaboration as well as a new measurement of the electroweak mixing angle with the CMS detector are presented. Special emphasis is put on a discussion of the modelling uncertainties and the potential of the latest low-$\\mu$ runs, recorded at the end of 2017 by both collaboration. In addition, the latest measurements of multi-boson final states as well as the electroweak production of single gauge bosons at 13 TeV are summarised. The study of these processes can be used to constrain anomalous gauge couplings in an effective field theory approach, allowing to bridge tests of the electroweak sector of the Standard Models also to Higgs boson production.

Unconventional phase transitions in liquid crystals

Science.gov (United States)

Kats, E. I.

2017-12-01

According to classical textbooks on thermodynamics or statistical physics, there are only two types of phase transitions: continuous, or second-order, in which the latent heat L is zero, and first-order, in which L ≠ 0. Present-day textbooks and monographs also mention another, stand-alone type—the Berezinskii-Kosterlitz-Thouless transition, which exists only in two dimensions and shares some features with first- and second-order phase transitions. We discuss examples of non-conventional thermodynamic behavior (i.e., which is inconsistent with the theoretical phase transition paradigm now universally accepted). For phase transitions in smectic liquid crystals, mechanisms for nonconventional behavior are proposed and the predictions they imply are examined.

Electroweak Physics at the LHC

CERN Document Server

Sommer, Philip; The ATLAS collaboration

2018-01-01

With the high integrated luminosities recorded at the LHC and the very good understanding of the LHC detectors, it is possible to measure electroweak observables to the highest precision. In this talk, we review the measurement of the W boson mass by the ATLAS Collaboration as well as the new measurement of the electroweak mixing angle with the CMS detector. Special focus is drawn on a discussion of the modeling uncertainties and the physics potential of the latest low-mu runs, recorded at the end of 2017 by both collaboration. In addition, we will present the latest measurements of multi-boson final states as well as the electroweak production of single gauge bosons at 13 TeV. The study of these processes can be used to constrain anomalous gauge couplings in an effective field theory approach, allowing to bridge tests of the electroweak sector of the Standard Models also to the Higgs-boson production.

Analysis of the phase structure in extended Higgs models

Energy Technology Data Exchange (ETDEWEB)

Seniuch, M.

2006-07-07

We study the generation of the baryon asymmetry in the context of electroweak baryogenesis in two different extensions of the Standard Model. First, we consider an effective theory, in which the Standard Model is augmented by an additional dimension-six Higgs operator. The effects of new physics beyond a cut-off scale are parameterized by this operator. The second model is the two-Higgs-doublet model, whose particle spectrum is extended by two further neutral and two charged heavy Higgs bosons. In both cases we focus on the properties of the electroweak phase transition, especially on its strength and the profile of the nucleating bubbles. After reviewing some general aspects of the electroweak phase transition and baryogenesis we derive the respective thermal effective potentials to one-loop order. We systematically study the parameter spaces, using numerical methods, and compute the strength of the phase transition and the wall thickness as a function of the Higgs masses. We find a strong first order transition for a light Higgs state with a mass up to about 200 GeV. In case of the dimension-six model the cut-off scale has to stay between 500 and 850 GeV, in the two-Higgs-doublet model one needs at least one heavy Higgs mass of 300 GeV. The wall thickness varies for both theories in the range roughly from two to fifteen, in units of the inverse critical temperature. We also estimate the size of the electron and neutron electric dipole moments, since new sources of CP violation give rise to them. In wide ranges of the parameter space we are not in conflict with the experimental bounds. Finally the baryon asymmetry, which is predicted by these models, is related to the Higgs mass and the other appropriate input parameters. In both models the measured baryon asymmetry can be achieved for natural values of the model parameters. (orig.)

Structural phase transitions and Huang scattering

International Nuclear Information System (INIS)

Yamada, Yasusada

1980-01-01

The usefulness of the application of the concept of Huang scattering to the understandings of the origin of diffuse scatterings near structural phase transitions are discussed. It is pointed out that in several phase transitions, the observed diffuse scatterings can not be interpreted in terms of critical fluctuations of the order parameters associated with the structural phase transitions, and that they are rather interpreted as Huang scattering due to random distribution of individual order parameter which is 'dressed' by strain fields. Examples to show effective applications of this concept to analyze the experimental X-ray data and whence to understand microscopic mechanisms of structural phase transitions are presented. (author)

Electroweak baryogenesis and the standard model

International Nuclear Information System (INIS)

Huet, P.

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 CP violation. The shortcomings of the standard model could be bypassed by enlarging the symmetry breaking sector and adding a new source of CP violation

Electroweak penguins at LHCb

CERN Document Server

AUTHOR|(CDS)2073177

2016-01-01

Electroweak penguin decays are flavour-changing neutral current processes, and are highly suppressed in the Stan- dard Model. They can only proceed via loop diagrams. Such decays may receive contributions from New Physics and change their decay behaviours like decay rate and angular distribution. Studying the properties of these decays thus provides a powerful method to probe for New Physics. In this contribution the most recent LHCb results on electroweak penguin decays are reported.

Electroweak penguins at LHCb

Science.gov (United States)

He, Jibo; LHCb Collaboration

2016-04-01

Electroweak penguin decays are flavour-changing neutral current processes, and are highly suppressed in the Standard Model. They can only proceed via loop diagrams. Such decays may receive contributions from New Physics and change their decay behaviours like decay rate and angular distribution. Studying the properties of these decays thus provides a powerful method to probe for New Physics. In this contribution the most recent LHCb results on electroweak penguin decays are reported.

Modern theories of phase transitions

International Nuclear Information System (INIS)

Rajaraman, R.

1979-01-01

Modern applications of the ideas of phase transitions to nuclear systems and the modern techniques as applied to familiar phase transitions in solid-state physics are discussed with illustrations. The phenomenon of pion condensation in nuclei and neutron stars, is presented as an example of phase transitions in nuclear systems. The central physical ideas behind this subject as well as techniques used to tackle it are broadly summarised. It is pointed out that unlike familiar examples of ferromagnetism or superconductivity, the order parameter here has spatial variation even in the ground state. Possible experimental consequences are discussed. As an example of the second category, the use of renormalisation group techniques in solid state physics is reviewed. The basic idea behind the renormalisation group in the infra-red (thermodynamic) limit is presented. The observed universality and scaling of critical exponents in second order phase transitions is explained in a model-independent way. (auth.)

Precision electroweak physics at the Tevatron

International Nuclear Information System (INIS)

James, Eric B.

2006-01-01

An overview of Tevatron electroweak measurements performed by the CDF and Dφ experiments is presented. The current status and future prospects for high precision measurements of electroweak parameters and detailed studies of boson production are highlighted. (author)

Electroweak vacuum instability and renormalized Higgs field vacuum fluctuations in the inflationary universe

Energy Technology Data Exchange (ETDEWEB)

Kohri, Kazunori [Institute of Particle and Nuclear Studies, KEK, 1-1 Oho, Tsukuba 305-0801 (Japan); Matsui, Hiroki, E-mail: kohri@post.kek.jp, E-mail: matshiro@post.kek.jp [The Graduate University for Advanced Studies (SOKENDAI), 1-1 Oho, Tsukuba 305-0801 (Japan)

2017-08-01

In this work, we investigated the electroweak vacuum instability during or after inflation. In the inflationary Universe, i.e., de Sitter space, the vacuum field fluctuations < δ φ {sup 2} > enlarge in proportion to the Hubble scale H {sup 2}. Therefore, the large inflationary vacuum fluctuations of the Higgs field < δ φ {sup 2} > are potentially catastrophic to trigger the vacuum transition to the negative-energy Planck-scale vacuum state and cause an immediate collapse of the Universe. However, the vacuum field fluctuations < δ φ {sup 2} >, i.e., the vacuum expectation values have an ultraviolet divergence, and therefore a renormalization is necessary to estimate the physical effects of the vacuum transition. Thus, in this paper, we revisit the electroweak vacuum instability from the perspective of quantum field theory (QFT) in curved space-time, and discuss the dynamical behavior of the homogeneous Higgs field φ determined by the effective potential V {sub eff}( φ ) in curved space-time and the renormalized vacuum fluctuations < δ φ {sup 2} >{sub ren} via adiabatic regularization and point-splitting regularization. We simply suppose that the Higgs field only couples the gravity via the non-minimal Higgs-gravity coupling ξ(μ). In this scenario, the electroweak vacuum stability is inevitably threatened by the dynamical behavior of the homogeneous Higgs field φ, or the formations of AdS domains or bubbles unless the Hubble scale is small enough H < Λ {sub I} .

Electroweak vacuum stability in the Higgs-Dilaton theory

Energy Technology Data Exchange (ETDEWEB)

Shkerin, A. [Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL),CH-1015, Lausanne (Switzerland); Institute for Nuclear Research of the Russian Academy of Sciences,60th October Anniversary prospect 7a, 117312, Moscow (Russian Federation)

2017-05-30

We study the stability of the Electroweak (EW) vacuum in a scale-invariant extension of the Standard Model and General Relativity, known as a Higgs-Dilaton theory. The safety of the EW vacuum against possible transition towards another vacuum is a necessary condition for the model to be phenomenologically acceptable. We find that, within a wide range of parameters of the theory, the decay rate is significantly suppressed compared to that of the Standard Model. We also discuss properties of a tunneling solution that are specific to the Higgs-Dilaton theory.

Dynamics of a quantum phase transition

International Nuclear Information System (INIS)

Zurek, W.H.

2005-01-01

We present two approaches to the non-equilibrium dynamics of a quench-induced phase transition in quantum Ising model. First approach retraces steps of the standard calculation to thermodynamic second order phase transitions in the quantum setting. The second calculation is purely quantum, based on the Landau-Zener formula for transition probabilities in processes that involve avoided level crossings. We show that the two approaches yield compatible results for the scaling of the defect density with the quench rate. We exhibit similarities between them, and comment on the insights they give into dynamics of quantum phase transitions. (author)

Electro-weak theory

International Nuclear Information System (INIS)

Deshpande, N.G.

1980-01-01

By electro-weak theory is meant the unified field theory that describes both weak and electro-magnetic interactions. The development of a unified electro-weak theory is certainly the most dramatic achievement in theoretical physics to occur in the second half of this century. It puts weak interactions on the same sound theoretical footing as quantum elecrodynamics. Many theorists have contributed to this development, which culminated in the works of Glashow, Weinberg and Salam, who were jointly awarded the 1979 Nobel Prize in physics. Some of the important ideas that contributed to this development are the theory of beta decay formulated by Fermi, Parity violation suggested by Lee and Yang, and incorporated into immensely successful V-A theory of weak interactions by Sudarshan and Marshak. At the same time ideas of gauge invariance were applied to weak interaction by Schwinger, Bludman and Glashow. Weinberg and Salam then went one step further and wrote a theory that is renormalizable, i.e., all higher order corrections are finite, no mean feat for a quantum field theory. The theory had to await the development of the quark model of hadrons for its completion. A description of the electro-weak theory is given

Quantum phase transitions of strongly correlated electron systems

International Nuclear Information System (INIS)

Imada, Masatoshi

1998-01-01

Interacting electrons in solids undergo various quantum phase transitions driven by quantum fluctuations. The quantum transitions take place at zero temperature by changing a parameter to control quantum fluctuations rather than thermal fluctuations. In contrast to classical phase transitions driven by thermal fluctuations, the quantum transitions have many different features where quantum dynamics introduces a source of intrinsic fluctuations tightly connected with spatial correlations and they have been a subject of recent intensive studies as we see below. Interacting electron systems cannot be fully understood without deep analyses of the quantum phase transitions themselves, because they are widely seen and play essential roles in many phenomena. Typical and important examples of the quantum phase transitions include metal-insulator transitions, (2, 3, 4, 5, 6, 7, 8, 9) metal-superconductor transitions, superconductor-insulator transitions, magnetic transitions to antiferromagnetic or ferromagnetic phases in metals as well as in Mott insulators, and charge ordering transitions. Here, we focus on three different types of transitions

Prediction of the Cabibbo angle in the vector model for electroweak interactions

International Nuclear Information System (INIS)

Reifler, F.; Morris, R.

1985-01-01

In a recent paper we presented a vector model for the electroweak interactions which is similar to the Weinberg--Salam model but differs in the following features. (1) In the vector model all fermion wave functions are bispinors or equivalently isotropic Yang--Mills triplets (as opposed to a state vector composed of a spinor and bispinors in the Weinberg--Salam model). Particles are distinguished by their Higgs fields. (2) The vector model predicts that sin 2 theta/sub W/ = 1/4 , where theta/sub W/ is the Weinberg angle. (3) The vector model accounts for conservation of lepton number, electric charge, and baryon number. (4) In the vector model an antiparticle is characterized by opposite lepton number, electric charge, and baryon number; yet both particles and antiparticles propagate forward in time with positive energies. In this paper we extend the vector theory to include interactions between fermions and the gauge bosons mediating the electroweak force. We model the bosons as Yang--Mills fields with their own Higgs fields. We further propose a specific configuration of Higgs fields for the u,d,s, and c quarks. With these features, the model accounts for electroweak transitions of quarks and leptons and predicts that cos theta/sub C/ = 0.9744, where theta/sub C/ is the Cabibbo angle. We further show that the vector model accounts for the intrinsic parity of particles and antiparticles, and parity violations and CPT invariance for electroweak interactions

Phase transitions in finite systems

Energy Technology Data Exchange (ETDEWEB)

Chomaz, Ph. [Grand Accelerateur National d' Ions Lourds (GANIL), DSM-CEA / IN2P3-CNRS, 14 - Caen (France); Gulminelli, F. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire

2002-07-01

In this series of lectures we will first review the general theory of phase transition in the framework of information theory and briefly address some of the well known mean field solutions of three dimensional problems. The theory of phase transitions in finite systems will then be discussed, with a special emphasis to the conceptual problems linked to a thermodynamical description for small, short-lived, open systems as metal clusters and data samples coming from nuclear collisions. The concept of negative heat capacity developed in the early seventies in the context of self-gravitating systems will be reinterpreted in the general framework of convexity anomalies of thermo-statistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. Finally a careful study of the thermodynamical limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. (authors)

Phase transitions in finite systems

International Nuclear Information System (INIS)

Chomaz, Ph.; Gulminelli, F.

2002-01-01

In this series of lectures we will first review the general theory of phase transition in the framework of information theory and briefly address some of the well known mean field solutions of three dimensional problems. The theory of phase transitions in finite systems will then be discussed, with a special emphasis to the conceptual problems linked to a thermodynamical description for small, short-lived, open systems as metal clusters and data samples coming from nuclear collisions. The concept of negative heat capacity developed in the early seventies in the context of self-gravitating systems will be reinterpreted in the general framework of convexity anomalies of thermo-statistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. Finally a careful study of the thermodynamical limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. (authors)

Non-equilibrium phase transition

International Nuclear Information System (INIS)

Mottola, E.; Cooper, F.M.; Bishop, A.R.; Habib, S.; Kluger, Y.; Jensen, N.G.

1998-01-01

This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Non-equilibrium phase transitions play a central role in a very broad range of scientific areas, ranging from nuclear, particle, and astrophysics to condensed matter physics and the material and biological sciences. The aim of this project was to explore the path to a deeper and more fundamental understanding of the common physical principles underlying the complex real time dynamics of phase transitions. The main emphasis was on the development of general theoretical tools to deal with non-equilibrium processes, and of numerical methods robust enough to capture the time-evolving structures that occur in actual experimental situations. Specific applications to Laboratory multidivisional efforts in relativistic heavy-ion physics (transition to a new phase of nuclear matter consisting of a quark-gluon plasma) and layered high-temperature superconductors (critical currents and flux flow at the National High Magnetic Field Laboratory) were undertaken

Predicting a new phase (T'') of two-dimensional transition metal di-chalcogenides and strain-controlled topological phase transition

Science.gov (United States)

Ma, Fengxian; Gao, Guoping; Jiao, Yalong; Gu, Yuantong; Bilic, Ante; Zhang, Haijun; Chen, Zhongfang; Du, Aijun

2016-02-01

Single layered transition metal dichalcogenides have attracted tremendous research interest due to their structural phase diversities. By using a global optimization approach, we have discovered a new phase of transition metal dichalcogenides (labelled as T''), which is confirmed to be energetically, dynamically and kinetically stable by our first-principles calculations. The new T'' MoS2 phase exhibits an intrinsic quantum spin Hall (QSH) effect with a nontrivial gap as large as 0.42 eV, suggesting that a two-dimensional (2D) topological insulator can be achieved at room temperature. Most interestingly, there is a topological phase transition simply driven by a small tensile strain of up to 2%. Furthermore, all the known MX2 (M = Mo or W; X = S, Se or Te) monolayers in the new T'' phase unambiguously display similar band topologies and strain controlled topological phase transitions. Our findings greatly enrich the 2D families of transition metal dichalcogenides and offer a feasible way to control the electronic states of 2D topological insulators for the fabrication of high-speed spintronics devices.Single layered transition metal dichalcogenides have attracted tremendous research interest due to their structural phase diversities. By using a global optimization approach, we have discovered a new phase of transition metal dichalcogenides (labelled as T''), which is confirmed to be energetically, dynamically and kinetically stable by our first-principles calculations. The new T'' MoS2 phase exhibits an intrinsic quantum spin Hall (QSH) effect with a nontrivial gap as large as 0.42 eV, suggesting that a two-dimensional (2D) topological insulator can be achieved at room temperature. Most interestingly, there is a topological phase transition simply driven by a small tensile strain of up to 2%. Furthermore, all the known MX2 (M = Mo or W; X = S, Se or Te) monolayers in the new T'' phase unambiguously display similar band topologies and strain controlled topological

How to quantify the transition phase during golf swing performance: Torsional load affects low back complaints during the transition phase.

Science.gov (United States)

Sim, Taeyong; Choi, Ahnryul; Lee, Soeun; Mun, Joung Hwan

2017-10-01

The transition phase of a golf swing is considered to be a decisive instant required for a powerful swing. However, at the same time, the low back torsional loads during this phase can have a considerable effect on golf-related low back pain (LBP). Previous efforts to quantify the transition phase were hampered by problems with accuracy due to methodological limitations. In this study, vector-coding technique (VCT) method was proposed as a comprehensive methodology to quantify the precise transition phase and examine low back torsional load. Towards this end, transition phases were assessed using three different methods (VCT, lead hand speed and X-factor stretch) and compared; then, low back torsional load during the transition phase was examined. As a result, the importance of accurate transition phase quantification has been documented. The largest torsional loads were observed in healthy professional golfers (10.23 ± 1.69 N · kg -1 ), followed by professional golfers with a history of LBP (7.93 ± 1.79 N · kg -1 ), healthy amateur golfers (1.79 ± 1.05 N · kg -1 ) and amateur golfers with a history of LBP (0.99 ± 0.87 N · kg -1 ), which order was equal to that of the transition phase magnitudes of each group. These results indicate the relationship between the transition phase and LBP history and the dependency of the torsional load magnitude on the transition phase.

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.

Electroweak results from the tevatron

International Nuclear Information System (INIS)

Wood, D.

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

Non-negligible electroweak penguin effects

International Nuclear Information System (INIS)

Guo Libo; Li Xingyi

1999-01-01

Starting from the leading logarithmic low energy effective Hamiltonian and the Bauer-Stech-Wirbe (BSW) model, the authors calculate the electroweak penguin effects in the two-body hadronic pure penguin processes of B-meson. In the case of B→PP and PV decay, the authors find that the processes involving external penguin diagrams receive large contribution from electroweak penguin effects which can even play dominant role

Dark Matter Decay between Phase Transitions at the Weak Scale.

Science.gov (United States)

Baker, Michael J; Kopp, Joachim

2017-08-11

We propose a new alternative to the weakly interacting massive particle paradigm for dark matter. Rather than being determined by thermal freeze-out, the dark matter abundance in this scenario is set by dark matter decay, which is allowed for a limited amount of time just before the electroweak phase transition. More specifically, we consider fermionic singlet dark matter particles coupled weakly to a scalar mediator S_{3} and to auxiliary dark sector fields, charged under the standard model gauge groups. Dark matter freezes out while still relativistic, so its abundance is initially very large. As the Universe cools down, the scalar mediator develops a vacuum expectation value (VEV), which breaks the symmetry that stabilizes dark matter. This allows dark matter to mix with charged fermions and decay. During this epoch, the dark matter abundance is reduced to give the value observed today. Later, the SM Higgs field also develops a VEV, which feeds back into the S_{3} potential and restores the dark sector symmetry. In a concrete model we show that this "VEV flip-flop" scenario is phenomenologically successful in the most interesting regions of its parameter space. We also comment on detection prospects at the LHC and elsewhere.

Effect of hyperons on nuclear phase transition

International Nuclear Information System (INIS)

Das, P.; Mallik, S.; Chaudhuri, G.

2016-01-01

Phase transition of nuclear system in heavy ion-collisions at intermediate energy has been studied well for many years and it has also been extended to strange nuclear matter. Recently, using the Canonical Thermodynamical Model (CTM), detailed work on multiplicity distribution of fragments produced from fragmentation of hypernuclear system shows the existence of phase transition or phase coexistence in strange system with Λ-hyperons. In present work we want to continue the investigation on phase transition with respect to some other thermodynamic observables like free energy, specific heat etc. in order to be confirmed about the nature of the transition

Generalized definitions of phase transitions

International Nuclear Information System (INIS)

Chomaz, Ph.; Gulminelli, F.

2001-09-01

We define a first order phase transition as a bimodality of the event distribution in the space of observations and we show that this is equivalent to a curvature anomaly of the thermodynamical potential and that it implies the Yang Lee behavior of the zeros of the partition sum. Moreover, it allows to study phase transitions out of equilibrium. (authors)

Quantum phase transition with dissipative frustration

Science.gov (United States)

Maile, D.; Andergassen, S.; Belzig, W.; Rastelli, G.

2018-04-01

We study the quantum phase transition of the one-dimensional phase model in the presence of dissipative frustration, provided by an interaction of the system with the environment through two noncommuting operators. Such a model can be realized in Josephson junction chains with shunt resistances and resistances between the chain and the ground. Using a self-consistent harmonic approximation, we determine the phase diagram at zero temperature which exhibits a quantum phase transition between an ordered phase, corresponding to the superconducting state, and a disordered phase, corresponding to the insulating state with localized superconducting charge. Interestingly, we find that the critical line separating the two phases has a nonmonotonic behavior as a function of the dissipative coupling strength. This result is a consequence of the frustration between (i) one dissipative coupling that quenches the quantum phase fluctuations favoring the ordered phase and (ii) one that quenches the quantum momentum (charge) fluctuations leading to a vanishing phase coherence. Moreover, within the self-consistent harmonic approximation, we analyze the dissipation induced crossover between a first and second order phase transition, showing that quantum frustration increases the range in which the phase transition is second order. The nonmonotonic behavior is reflected also in the purity of the system that quantifies the degree of correlation between the system and the environment, and in the logarithmic negativity as an entanglement measure that encodes the internal quantum correlations in the chain.

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 limitin...... 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....

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.

Quantum transport and electroweak baryogenesis

International Nuclear Information System (INIS)

Konstandin, Thomas

2013-02-01

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.

Microscopic origin of black hole reentrant phase transitions

Science.gov (United States)

Zangeneh, M. Kord; Dehyadegari, A.; Sheykhi, A.; Mann, R. B.

2018-04-01

Understanding the microscopic behavior of the black hole ingredients has been one of the important challenges in black hole physics during the past decades. In order to shed some light on the microscopic structure of black holes, in this paper, we explore a recently observed phenomenon for black holes namely reentrant phase transition, by employing the Ruppeiner geometry. Interestingly enough, we observe two properties for the phase behavior of small black holes that leads to reentrant phase transition. They are correlated and they are of the interaction type. For the range of pressure in which the system underlies reentrant phase transition, it transits from the large black holes phase to the small one which possesses higher correlation than the other ranges of pressures. On the other hand, the type of interaction between small black holes near the large/small transition line differs for usual and reentrant phase transitions. Indeed, for the usual case, the dominant interaction is repulsive whereas for the reentrant case we encounter an attractive interaction. We show that in the reentrant phase transition case, the small black holes behave like a bosonic gas whereas in the usual phase transition case, they behave like a quantum anyon gas.

New strong interactions above the electroweak scale

International Nuclear Information System (INIS)

White, A.R.

1994-01-01

Theoretical arguments for a new higher-color quark sector, based on Pomeron physics in QCD, are briefly described. The electroweak symmetry-breaking, Strong CP conservation, and electroweak scale CP violation, that is naturally produced by this sector is also outlined. A further consequence is that above the electroweak scale there will be a radical change in the strong interaction. Electroweak states, in particular multiple W's and Z's, and new, semi-stable, very massive, baryons, will be commonly produced. The possible correlation of expected phenomena with a wide range of observed Cosmic Ray effects at and above the primary spectrum knee is described. Related phenomena that might be seen in the highest energy hard scattering events at the Fermilab Tevatron, some of which could be confused with top production, are also briefly discussed

The quantum phase-transitions of water

Science.gov (United States)

Fillaux, François

2017-08-01

It is shown that hexagonal ices and steam are macroscopically quantum condensates, with continuous spacetime-translation symmetry, whereas liquid water is a quantum fluid with broken time-translation symmetry. Fusion and vaporization are quantum phase-transitions. The heat capacities, the latent heats, the phase-transition temperatures, the critical temperature, the molar volume expansion of ice relative to water, as well as neutron scattering data and dielectric measurements are explained. The phase-transition mechanisms along with the key role of quantum interferences and that of Hartley-Shannon's entropy are enlightened. The notions of chemical bond and force-field are questioned.

Phase transition in SO(3) gauge theory

International Nuclear Information System (INIS)

Datta, Saumen; Gavai, Rajiv V.

1998-01-01

The phase transition in SO(3) lattice gauge theory is investigated by Monte Carlo techniques with a view (i) to understand the relationship between the bulk transition and the deconfinement transition, and (ii) to resolve the current ambiguity about the nature of the high temperature phase. By introduction of a magnetic field, it was shown that the +ve and -ve values of a > correspond to the same phase. Studies on different sized lattices lead to the conclusion that in SO(3), there is only one transition, which is deconfining in nature. (author)

Microgravity Two-Phase Flow Transition

Science.gov (United States)

Parang, M.; Chao, D.

1999-01-01

Two-phase flows under microgravity condition find a large number of important applications in fluid handling and storage, and spacecraft thermal management. Specifically, under microgravity condition heat transfer between heat exchanger surfaces and fluids depend critically on the distribution and interaction between different fluid phases which are often qualitatively different from the gravity-based systems. Heat transfer and flow analysis in two-phase flows under these conditions require a clear understanding of the flow pattern transition and development of appropriate dimensionless scales for its modeling and prediction. The physics of this flow is however very complex and remains poorly understood. This has led to various inadequacies in flow and heat transfer modeling and has made prediction of flow transition difficult in engineering design of efficient thermal and flow systems. In the present study the available published data for flow transition under microgravity condition are considered for mapping. The transition from slug to annular flow and from bubbly to slug flow are mapped using dimensionless variable combination developed in a previous study by the authors. The result indicate that the new maps describe the flow transitions reasonably well over the range of the data available. The transition maps are examined and the results are discussed in relation to the presumed balance of forces and flow dynamics. It is suggested that further evaluation of the proposed flow and transition mapping will require a wider range of microgravity data expected to be made available in future studies.

Wilson loop's phase transition probed by non-local observable

Directory of Open Access Journals (Sweden)

Hui-Ling Li

2018-04-01

Full Text Available In order to give further insights into the holographic Van der Waals phase transition, it would be of great interest to investigate the behavior of Wilson loop across the holographic phase transition for a higher dimensional hairy black hole. We offer a possibility to proceed with a numerical calculation in order to discussion on the hairy black hole's phase transition, and show that Wilson loop can serve as a probe to detect a phase structure of the black hole. Furthermore, for a first order phase transition, we calculate numerically the Maxwell's equal area construction; and for a second order phase transition, we also study the critical exponent in order to characterize the Wilson loop's phase transition.

Problem-Solving Phase Transitions During Team Collaboration.

Science.gov (United States)

Wiltshire, Travis J; Butner, Jonathan E; Fiore, Stephen M

2018-01-01

Multiple theories of problem-solving hypothesize that there are distinct qualitative phases exhibited during effective problem-solving. However, limited research has attempted to identify when transitions between phases occur. We integrate theory on collaborative problem-solving (CPS) with dynamical systems theory suggesting that when a system is undergoing a phase transition it should exhibit a peak in entropy and that entropy levels should also relate to team performance. Communications from 40 teams that collaborated on a complex problem were coded for occurrence of problem-solving processes. We applied a sliding window entropy technique to each team's communications and specified criteria for (a) identifying data points that qualify as peaks and (b) determining which peaks were robust. We used multilevel modeling, and provide a qualitative example, to evaluate whether phases exhibit distinct distributions of communication processes. We also tested whether there was a relationship between entropy values at transition points and CPS performance. We found that a proportion of entropy peaks was robust and that the relative occurrence of communication codes varied significantly across phases. Peaks in entropy thus corresponded to qualitative shifts in teams' CPS communications, providing empirical evidence that teams exhibit phase transitions during CPS. Also, lower average levels of entropy at the phase transition points predicted better CPS performance. We specify future directions to improve understanding of phase transitions during CPS, and collaborative cognition, more broadly. Copyright © 2017 Cognitive Science Society, Inc.

Emergent Electroweak Symmetry Breaking with Composite W, Z Bosons

CERN Document Server

Cui, Yanou; Wells, James D

2009-01-01

We present a model of electroweak symmetry breaking in a warped extra dimension where electroweak symmetry is broken at the UV (or Planck) scale. An underlying conformal symmetry is broken at the IR (or TeV) scale generating masses for the electroweak gauge bosons without invoking a Higgs mechanism. By the AdS/CFT correspondence the W,Z bosons are identified as composite states of a strongly-coupled gauge theory, suggesting that electroweak symmetry breaking is an emergent phenomenon at the IR scale. The model satisfies electroweak precision tests with reasonable fits to the S and T parameter. In particular the T parameter is sufficiently suppressed since the model naturally admits a custodial SU(2) symmetry. The composite nature of the W,Z-bosons provide a novel possibility of unitarizing WW scattering via form factor suppression. Constraints from LEP and the Tevatron as well as discovery opportunities at the LHC are discussed for these composite electroweak gauge bosons.

Late-time cosmological phase transitions

International Nuclear Information System (INIS)

Schramm, D.N.

1990-11-01

It is shown that the potential galaxy formation and large-scale structure problems of objects existing at high redshifts (Z approx-gt 5), structures existing on scales of 100M pc as well as velocity flows on such scales, and minimal microwave anisotropies (ΔT/T) approx-lt 10 -5 can be solved if the seeds needed to generate structure form in a vacuum phase transition after decoupling. It is argued that the basic physics of such a phase transition is no more exotic than that utilized in the more traditional GUT scale phase transitions, and that, just as in the GUT case, significant random gaussian fluctuations and/or topological defects can form. Scale lengths of ∼100M pc for large-scale structure as well as ∼1 M pc for galaxy formation occur naturally. Possible support for new physics that might be associated with such a late-time transition comes from the preliminary results of the SAGE solar neutrino experiment, implying neutrino flavor mixing with values similar to those required for a late-time transition. It is also noted that a see-saw model for the neutrino masses might also imply a tau neutrino mass that is an ideal hot dark matter candidate. However, in general either hot or cold dark matter can be consistent with a late-time transition. 47 refs., 2 figs

Phase transitions and neutron scattering

International Nuclear Information System (INIS)

Shirane, G.

1993-01-01

A review is given of recent advances in neutron scattering studies of solid state physics. I have selected the study of a structural phase transition as the best example to demonstrate the power of neutron scattering techniques. Since energy analysis is relatively easy, the dynamical aspects of a transition can be elucidated by the neutron probe. I shall discuss in some detail current experiments on the 100 K transition in SrTiO 3 , the crystal which has been the paradigm of neutron studies of phase transitions for many years. This new experiment attempts to clarify the relation between the neutron central peak, observed in energy scans, and the two length scales observed in recent x-ray diffraction studies where only scans in momentum space are possible. (author)

Electroweak physics at LEP2

CERN Document Server

Hemingway, Richard J

2002-01-01

On 2 November 2000 the LEP machine was finally closed after 12 years of glorious running. With the 4 operating detectors, ALEPH, DELPHI, L3, and OPAL, an enormous wealth of new data at the highest centre- of-mass energies has been recorded. These lectures will focus on aspects of electroweak physics within the energy span of LEP2, namely 130-209 GeV. All current data are in very good agreement with the electroweak standard model. (50 refs).

TRISTAN electroweak working group report

International Nuclear Information System (INIS)

Hagiwara, K.

1995-01-01

Model-independent measurements of quantities sensitive to the electroweak physics at TRISTAN energies are proposed for the processes e + e - → e + e - , μ + μ - , τ + τ - , hadrons and heavy-quark (charm- and bottom-quark) jets. Factorization of the scattering amplitudes into the part which is sensitive to short-distance electroweak physics and the rest which is sensitive to long-distance QED and QCD corrections is made, and uncertainties in the latter are studied quantitatively by using existing programs. Electroweak observables are then chosen for each processes such that the uncertainty from the long-distance physics is small and that they can be updated when we reach a better understanding of the QED and QCD corrections. The new scheme will make the data from high luminosity TRISTAN experiments useful for particle physicists of the present as well as those of the future generation. (author)

Quantum phase transitions in random XY spin chains

International Nuclear Information System (INIS)

Bunder, J.E.; McKenzie, R.H.

2000-01-01

Full text: The XY spin chain in a transverse field is one of the simplest quantum spin models. It is a reasonable model for heavy fermion materials such as CeCu 6-x Au x . It has two quantum phase transitions: the Ising transition and the anisotropic transition. Quantum phase transitions occur at zero temperature. We are investigating what effect the introduction of randomness has on these quantum phase transitions. Disordered systems which undergo quantum phase transitions can exhibit new universality classes. The universality class of a phase transition is defined by the set of critical exponents. In a random system with quantum phase transitions we can observe Griffiths-McCoy singularities. Such singularities are observed in regions which have no long range order, so they are not classified as critical regions, yet they display phenomena normally associated with critical points, such as a diverging susceptibility. Griffiths-McCoy phases are due to rare regions with stronger than! average interactions and may be present far from the quantum critical point. We show how the random XY spin chain may be mapped onto a random Dirac equation. This allows us to calculate the density of states without making any approximations. From the density of states we can describe the conditions which should allow a Griffiths-McCoy phase. We find that for the Ising transition the dynamic critical exponent, z, is not universal. It is proportional to the disorder strength and inversely proportional to the energy gap, hence z becomes infinite at the critical point where the energy gap vanishes

Phase transition phenomenon: A compound measure analysis

Science.gov (United States)

Kang, Bo Soo; Park, Chanhi; Ryu, Doojin; Song, Wonho

2015-06-01

This study investigates the well-documented phenomenon of phase transition in financial markets using combined information from both return and volume changes within short time intervals. We suggest a new measure for the phase transition behaviour of markets, calculated as a return distribution conditional on local variance in volume imbalance, and show that this measure successfully captures phase transition behaviour under various conditions. We analyse the intraday trade and quote dataset from the KOSPI 200 index futures, which includes detailed information on the original order size and the type of each initiating investor. We find that among these two competing factors, the submitted order size yields more explanatory power on the phenomenon of market phase transition than the investor type.

Behavior of the antiferromagnetic phase transition near the fermion condensation quantum phase transition in YbRh{sub 2}Si{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Shaginyan, V.R., E-mail: vrshag@thd.pnpi.spb.r [Petersburg Nuclear Physics Institute, RAS, Gatchina 188300 (Russian Federation); Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Amusia, M.Ya. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Popov, K.G. [Komi Science Center, Ural Division, RAS, Syktyvkar 167982 (Russian Federation)

2010-01-11

Low-temperature specific-heat measurements on YbRh{sub 2}Si{sub 2} at the second order antiferromagnetic (AF) phase transition reveal a sharp peak at T{sub N}=72 mK. The corresponding critical exponent alpha turns out to be alpha=0.38, which differs significantly from that obtained within the framework of the fluctuation theory of second order phase transitions based on the scale invariance, where alphaapprox =0.1. We show that under the application of magnetic field the curve of the second order AF phase transitions passes into a curve of the first order ones at the tricritical point leading to a violation of the critical universality of the fluctuation theory. This change of the phase transition is generated by the fermion condensation quantum phase transition. Near the tricritical point the Landau theory of second order phase transitions is applicable and gives alphaapprox =1/2. We demonstrate that this value of alpha is in good agreement with the specific-heat measurements.

Structural Phase Transition Nomenclature, Report of an IUCr Working Group on Phase Transition Nomenclature

NARCIS (Netherlands)

Toleddano, J.C.; Glazer, A.M.; Hahn, Th.; Parthe, E.; Roth, R.S.; Berry, R.S.; Metselaar, R.; Abrahams, S.C.

1998-01-01

A compact and intuitive nomenclature is recommended for naming each phase formed by a given material in a sequence of phase transitions as a function of temperature and/or pressure. The most commonly used label for each phase in a sequence, such as [alpha], [beta], ..., I, II, ... etc., is included

((ε')/(ε)) and the electroweak penguin contribution

International Nuclear Information System (INIS)

Cirigliano, V.; Donoghue, J.F.; Golowich, E.; Maltman, K.

2003-01-01

Our dispersive sum rule calculation of the electroweak penguin contribution to ((ε')/(ε)) is reviewed. A more recent analysis based on the finite-energy sum rule approach is described. Finally, a new determination of the electroweak penguin contribution to ((ε')/(ε)) is presented

The Structural Phase Transition in Octaflournaphtalene

DEFF Research Database (Denmark)

Mackenzie, Gordon A.; Arthur, J. W.; Pawley, G. S.

1977-01-01

The phase transition in octafluoronaphthalene has been investigated by Raman scattering and neutron powder diffraction. The weight of the experimental evidence points to a unit cell doubling in the a direction, but with no change in space group symmetry. Lattice dynamics calculations support...... this evidence and indicate that the mechanism of the phase transition may well be the instability of a zone boundary acoustic mode of librational character. The structure of the low-temperature phase has been refined and the Raman spectra of the upper and lower phases are reported....

Electroweak measurements with the ATLAS detector

CERN Document Server

Krasnopevtsev, Dimitriy; The ATLAS collaboration

2015-01-01

Electroweak measurements with the ATLAS detector -First Run 2 measurements of electroweak processes -Run 1 measurements of SM parameters, i.e. W mass and weak mixing angle -Recent Run 1 measurements of di- and multi-boson production cross-sections as well as vector boson fusion and scattering processes at 8 TeV -Recent Run 1 measurements of exclusive di-lepton and WW production

Phases and phase transitions of S=1 bosons

Indian Academy of Sciences (India)

smukerjee

Quantum phases and phase transitions of bosons. Subroto Mukerjee. Dept. of Physics & Centre for Quantum. Information and Quantum Computing (CQIQC). Indian Institute of Science, Bangalore. 77th annual meeting of the IAS, Nov. 20 2011, PRL Ahmedabad ...

Unconventional phase transitions in a constrained single polymer chain

International Nuclear Information System (INIS)

Klushin, L I; Skvortsov, A M

2011-01-01

Phase transitions were recognized among the most fascinating phenomena in physics. Exactly solved models are especially important in the theory of phase transitions. A number of exactly solved models of phase transitions in a single polymer chain are discussed in this review. These are three models demonstrating the second order phase transitions with some unusual features: two-dimensional model of β-structure formation, the model of coil–globule transition and adsorption of a polymer chain grafted on the solid surface. We also discuss models with first order phase transitions in a single macromolecule which admit not only exact analytical solutions for the partition function with explicit finite-size effects but also the non-equilibrium free energy as a function of the order parameter (Landau function) in closed analytical form. One of them is a model of mechanical desorption of a macromolecule, which demonstrates an unusual first order phase transition with phase coexistence within a single chain. Features of first and second order transitions become mixed here due to phase coexistence which is not accompanied by additional interfacial free energy. Apart from that, there exist several single-chain models belonging to the same class (adsorption of a polymer chain tethered near the solid surface or liquid–liquid interface, and escape transition upon compressing a polymer between small pistons) that represent examples of a highly unconventional first order phase transition with several inter-related unusual features: no simultaneous phase coexistence, and hence no phase boundary, non-concave thermodynamic potential and non-equivalence of conjugate ensembles. An analysis of complex zeros of partition functions upon approaching the thermodynamic limit is presented for models with and without phase coexistence. (topical review)

Baryogenesis at the electroweak scale

Energy Technology Data Exchange (ETDEWEB)

Kundu, A [Saha Inst. of Nuclear Physics, Calcutta (India); Mallik, S [Saha Inst. of Nuclear Physics, Calcutta (India)

1995-10-01

The generation of the baryon asymmetry of the universe is considered in the standard model of the electroweak theory with simple extensions of the Higgs sector. The propagation of quarks of masses up to about 5 GeV are considered, taking into account their markedly different dispersion relations due to propagation through the hot electroweak plasma. It is shown that the contribution of the b quark to the baryon asymmetry can be comparable to that for the t quark considered earlier. (orig.)

Baryogenesis at the electroweak scale

International Nuclear Information System (INIS)

Kundu, A.; Mallik, S.

1995-01-01

The generation of the baryon asymmetry of the universe is considered in the standard model of the electroweak theory with simple extensions of the Higgs sector. The propagation of quarks of masses up to about 5 GeV are considered, taking into account their markedly different dispersion relations due to propagation through the hot electroweak plasma. It is shown that the contribution of the b quark to the baryon asymmetry can be comparable to that for the t quark considered earlier. (orig.)

Electroweak baryogenesis in extensions of the standard model

International Nuclear Information System (INIS)

Fromme, L.

2006-01-01

We investigate the generation of the baryon asymmetry in two extensions of the Standard Model; these are the Φ 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.)

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.)

Phase transitions and baryogenesis from decays

Science.gov (United States)

Shuve, Brian; Tamarit, Carlos

2017-10-01

We study scenarios in which the baryon asymmetry is generated from the decay of a particle whose mass originates from the spontaneous breakdown of a symmetry. This is realized in many models, including low-scale leptogenesis and theories with classical scale invariance. Symmetry breaking in the early universe proceeds through a phase transition that gives the parent particle a time-dependent mass, which provides an additional departure from thermal equilibrium that could modify the efficiency of baryogenesis from out-of-equilibrium decays. We characterize the effects of various types of phase transitions and show that an enhancement in the baryon asymmetry from decays is possible if the phase transition is of the second order, although such models are typically fine-tuned. We also stress the role of new annihilation modes that deplete the parent particle abundance in models realizing such a phase transition, reducing the efficacy of baryogenesis. A proper treatment of baryogenesis in such models therefore requires the inclusion of the effects we study in this paper.

Sound speed during the QCD phase transition

International Nuclear Information System (INIS)

Nagasawa, Michiyasu; Yokoyama, Jun'ichi

1998-01-01

The Jeans scale is estimated during the coexistence epoch of quark-gluon and hadron phases in the first-order QCD phase transition. It is shown that, contrary to previous claims, reduction of the sound speed is so little that the phase transition does not affect evolution of cosmological density fluctuations appreciably. (author)

Non-equilibrium phase transitions in complex plasma

International Nuclear Information System (INIS)

Suetterlin, K R; Raeth, C; Ivlev, A V; Thomas, H M; Khrapak, S; Zhdanov, S; Rubin-Zuzic, M; Morfill, G E; Wysocki, A; Loewen, H; Goedheer, W J; Fortov, V E; Lipaev, A M; Molotkov, V I; Petrov, O F

2010-01-01

Complex plasma being the 'plasma state of soft matter' is especially suitable for investigations of non-equilibrium phase transitions. Non-equilibrium phase transitions can manifest in dissipative structures or self-organization. Two specific examples are lane formation and phase separation. Using the permanent microgravity laboratory PK-3 Plus, operating onboard the International Space Station, we performed unique experiments with binary mixtures of complex plasmas that showed both lane formation and phase separation. These observations have been augmented by comprehensive numerical and theoretical studies. In this paper we present an overview of our most important results. In addition we put our results in context with research of complex plasmas, binary systems and non-equilibrium phase transitions. Necessary and promising future complex plasma experiments on phase separation and lane formation are briefly discussed.

Phase transition of aragonite in abalone nacre

Science.gov (United States)

An, Yuanlin; Liu, Zhiming; Wu, Wenjian

2013-04-01

Nacre is composed of about 95 vol.% aragonite and 5 vol.% biopolymer and famous for its "brick and mortar" microstructure. The phase transition temperature of aragonite in nacre is lower than the pure aragonite. In situ XRD was used to identify the phase transition temperature from aragonite to calcite in nacre, based on the analysis of TG-DSC of fresh nacre and demineralized nacre. The results indicate that the microstructure and biopolymer are the two main factors that influence the phase transition temperature of aragonite in nacre.

Mixed-order phase transition in a colloidal crystal

Science.gov (United States)

Alert, Ricard; Tierno, Pietro; Casademunt, Jaume

2017-12-01

Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid-solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field H. At the transition field Hs, the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length ξ∝|H2-Hs2|-1/2. Mean-field critical exponents are predicted, since the upper critical dimension of the transition is du=2. Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.

Mixed-order phase transition in a colloidal crystal.

Science.gov (United States)

Alert, Ricard; Tierno, Pietro; Casademunt, Jaume

2017-12-05

Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid-solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field [Formula: see text] At the transition field [Formula: see text], the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length [Formula: see text] Mean-field critical exponents are predicted, since the upper critical dimension of the transition is [Formula: see text] Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.

Phase transitions of W condensation for the universe with finite fermion density

International Nuclear Information System (INIS)

Kalashnikov, O.K.; Perez Rojas, H.; Institute of Cybernetics, Mathematics and Physics, Cuban Academy of Sciences, Havana, Cuba)

1989-01-01

The phase diagrams of W condensation are established in the electroweak theory with a finite fermion density under conditions of neutral and electric charge conservation. We found for the universe with a zero neutral charge density that the W condensate occurs at any small fermion density ρ. This appears at first near the point of symmetry restoration. This condensate exists only in the finite-temperature region and evaporates completely or partially, when the temperature goes to zero

Gravitational waves from global second order phase transitions

Energy Technology Data Exchange (ETDEWEB)

Jr, John T. Giblin [Department of Physics, Kenyon College, 201 North College Rd, Gambier, OH 43022 (United States); Price, Larry R.; Siemens, Xavier; Vlcek, Brian, E-mail: giblinj@kenyon.edu, E-mail: larryp@caltech.edu, E-mail: siemens@gravity.phys.uwm.edu, E-mail: bvlcek@uwm.edu [Center for Gravitation and Cosmology, Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States)

2012-11-01

Global second-order phase transitions are expected to produce scale-invariant gravitational wave spectra. In this manuscript we explore the dynamics of a symmetry-breaking phase transition using lattice simulations. We explicitly calculate the stochastic gravitational wave background produced during the transition and subsequent self-ordering phase. We comment on this signal as it compares to the scale-invariant spectrum produced during inflation.

High temperature phase transitions without infrared divergences

International Nuclear Information System (INIS)

Tetradis, N.; Wetterich, C.

1993-09-01

The most commonly used method for the study of high temperature phase transitions is based on the perturbative evaluation of the temperature dependent effective potential. This method becomes unreliable in the case of a second order or weakly first order phase transition, due to the appearance of infrared divergences. These divergences can be controlled through the method of the effective average action which employs renormalization group ideas. We report on the study of the high temperature phase transition for the N-component φ 4 theory. A detailed quantitative picture of the second order phase transition is presented, including the critical exponents for the behaviour in the vicinity of the critical temperature. An independent check of the results is obtained in the large N limit, and contact with the perturbative approach is established through the study of the Schwinger-Dyson equations. (orig.)

Probabilistic physical characteristics of phase transitions at highway bottlenecks: incommensurability of three-phase and two-phase traffic-flow theories.

Science.gov (United States)

Kerner, Boris S; Klenov, Sergey L; Schreckenberg, Michael

2014-05-01

Physical features of induced phase transitions in a metastable free flow at an on-ramp bottleneck in three-phase and two-phase cellular automaton (CA) traffic-flow models have been revealed. It turns out that at given flow rates at the bottleneck, to induce a moving jam (F → J transition) in the metastable free flow through the application of a time-limited on-ramp inflow impulse, in both two-phase and three-phase CA models the same critical amplitude of the impulse is required. If a smaller impulse than this critical one is applied, neither F → J transition nor other phase transitions can occur in the two-phase CA model. We have found that in contrast with the two-phase CA model, in the three-phase CA model, if the same smaller impulse is applied, then a phase transition from free flow to synchronized flow (F → S transition) can be induced at the bottleneck. This explains why rather than the F → J transition, in the three-phase theory traffic breakdown at a highway bottleneck is governed by an F → S transition, as observed in real measured traffic data. None of two-phase traffic-flow theories incorporates an F → S transition in a metastable free flow at the bottleneck that is the main feature of the three-phase theory. On the one hand, this shows the incommensurability of three-phase and two-phase traffic-flow theories. On the other hand, this clarifies why none of the two-phase traffic-flow theories can explain the set of fundamental empirical features of traffic breakdown at highway bottlenecks.

Renormalization group approach to QCD phase transitions

International Nuclear Information System (INIS)

Midorikawa, S.; Yoshimoto, S.; So, H.

1987-01-01

Effective scalar theories for QCD are proposed to investigate the deconfining and chiral phase transitions. The orders of the phase transitions are determined by infrared stabilities of the fixed points. It is found that the transitions in SU(3) gauge theories are of 1st order for any number of massless flavors. The cases of SU(2) and SU(4) gauge theories are also discussed. (orig.)

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.

Phase transitions in nonequilibrium traffic theory

Energy Technology Data Exchange (ETDEWEB)

Zhang, H.M.

2000-02-01

This paper uses the center difference scheme of Lax-Friedrichs to numerically solve a newly developed continuum traffic flow theory and the kinematic theory of Lighthill and Whitham, and Richards, and it studies the flow-concentration phase transitions in flow containing both shock and rarefaction waves. A homogeneous road with finite length was modeled by both theories. Numerical simulations show that both theories yield nearly identical results for two representative Riemann problems--one has a shock solution and the other a rarefaction wave solution. Their phase transition curves, however, are different: those derived from the new theory have two branches--one for acceleration flow and one for deceleration flow, whereas those derived from the LWR theory comprise a single curve--the equilibrium curve. The phase transition curves in the shock case agree well with certain experimental observations but disagree with others. This disagreement may be resolved by studying transitions among nonequilibrium states, which awaits further development of a more accurate finite difference approximation of the nonequilibrium theory.

Dynamical quantum phase transitions: a review

Science.gov (United States)

Heyl, Markus

2018-05-01

Quantum theory provides an extensive framework for the description of the equilibrium properties of quantum matter. Yet experiments in quantum simulators have now opened up a route towards the generation of quantum states beyond this equilibrium paradigm. While these states promise to show properties not constrained by equilibrium principles, such as the equal a priori probability of the microcanonical ensemble, identifying the general properties of nonequilibrium quantum dynamics remains a major challenge, especially in view of the lack of conventional concepts such as free energies. The theory of dynamical quantum phase transitions attempts to identify such general principles by lifting the concept of phase transitions to coherent quantum real-time evolution. This review provides a pedagogical introduction to this field. Starting from the general setting of nonequilibrium dynamics in closed quantum many-body systems, we give the definition of dynamical quantum phase transitions as phase transitions in time with physical quantities becoming nonanalytic at critical times. We summarize the achieved theoretical advances as well as the first experimental observations, and furthermore provide an outlook to major open questions as well as future directions of research.

Dynamical quantum phase transitions: a review.

Science.gov (United States)

Heyl, Markus

2018-05-01

Quantum theory provides an extensive framework for the description of the equilibrium properties of quantum matter. Yet experiments in quantum simulators have now opened up a route towards the generation of quantum states beyond this equilibrium paradigm. While these states promise to show properties not constrained by equilibrium principles, such as the equal a priori probability of the microcanonical ensemble, identifying the general properties of nonequilibrium quantum dynamics remains a major challenge, especially in view of the lack of conventional concepts such as free energies. The theory of dynamical quantum phase transitions attempts to identify such general principles by lifting the concept of phase transitions to coherent quantum real-time evolution. This review provides a pedagogical introduction to this field. Starting from the general setting of nonequilibrium dynamics in closed quantum many-body systems, we give the definition of dynamical quantum phase transitions as phase transitions in time with physical quantities becoming nonanalytic at critical times. We summarize the achieved theoretical advances as well as the first experimental observations, and furthermore provide an outlook to major open questions as well as future directions of research.

Density Functional Theory for Phase-Ordering Transitions

Energy Technology Data Exchange (ETDEWEB)

Wu, Jianzhong [Univ. of California, Riverside, CA (United States)

2016-03-30

Colloids display astonishing structural and dynamic properties that can be dramatically altered by modest changes in the solution condition or an external field. This complex behavior stems from a subtle balance of colloidal forces and intriguing mesoscopic and macroscopic phase transitions that are sensitive to the processing conditions and the dispersing environment. Whereas the knowledge on the microscopic structure and phase behavior of colloidal systems at equilibrium is now well-advanced, quantitative predictions of the dynamic properties and the kinetics of phase-ordering transitions in colloids are not always realized. Many important mesoscopic and off-equilibrium colloidal states remain poorly understood. The proposed research aims to develop a new, unifying approach to describe colloidal dynamics and the kinetics of phase-ordering transitions based on accomplishments from previous work for the equilibrium properties of both uniform and inhomogeneous systems and on novel concepts from the state-of-the-art dynamic density functional theory. In addition to theoretical developments, computational research is designed to address a number of fundamental questions on phase-ordering transitions in colloids, in particular those pertinent to a competition of the dynamic pathways leading to various mesoscopic structures, off-equilibrium states, and crystalline phases. By providing a generic theoretical framework to describe equilibrium, metastable as well as non-ergodic phase transitions concurrent with the colloidal self-assembly processes, accomplishments from this work will have major impacts on both fundamental research and technological applications.

Problem-solving phase transitions during team collaboration

DEFF Research Database (Denmark)

Wiltshire, Travis; Butner, Jonathan E.; Fiore, Stephen M.

2018-01-01

) with dynamical systems theory suggesting that when a system is undergoing a phase transition it should exhibit a peak in entropy and that entropy levels should also relate to team performance. Communications from 40 teams that collaborated on a complex problem were coded for occurrence of problem......-solving processes. We applied a sliding window entropy technique to each team's communications and specified criteria for (a) identifying data points that qualify as peaks and (b) determining which peaks were robust. We used multilevel modeling, and provide a qualitative example, to evaluate whether phases exhibit...... phases. Peaks in entropy thus corresponded to qualitative shifts in teams’ CPS communications, providing empirical evidence that teams exhibit phase transitions during CPS. Also, lower average levels of entropy at the phase transition points predicted better CPS performance. We specify future directions...

Computational advances in transition phase analysis

International Nuclear Information System (INIS)

Morita, K.; Kondo, S.; Tobita, Y.; Shirakawa, N.; Brear, D.J.; Fischer, E.A.

1994-01-01

In this paper, historical perspective and recent advances are reviewed on computational technologies to evaluate a transition phase of core disruptive accidents in liquid-metal fast reactors. An analysis of the transition phase requires treatment of multi-phase multi-component thermohydraulics coupled with space- and energy-dependent neutron kinetics. Such a comprehensive modeling effort was initiated when the program of SIMMER-series computer code development was initiated in the late 1970s in the USA. Successful application of the latest SIMMER-II in USA, western Europe and Japan have proved its effectiveness, but, at the same time, several areas that require further research have been identified. Based on the experience and lessons learned during the SIMMER-II application through 1980s, a new project of SIMMER-III development is underway at the Power Reactor and Nuclear Fuel Development Corporation (PNC), Japan. The models and methods of SIMMER-III are briefly described with emphasis on recent advances in multi-phase multi-component fluid dynamics technologies and their expected implication on a future reliable transition phase analysis. (author)

Critical Line of the Deconfinement Phase Transitions

Science.gov (United States)

Gorenstein, Mark I.

Phase diagram of strongly interacting matter is discussed within the exactly solvable statistical model of the quark-gluon bags. The model predicts two phases of matter: the hadron gas at a low temperature T and baryonic chemical potential μ B , and the quark-gluon gas at a high T and/or μ B . The nature of the phase transition depends on a form of the bag massvolume spectrum (its pre-exponential factor), which is expected to change with the μ B /T ratio. It is therefore likely that the line of the 1 st order transition at a high μ B/T ratio is followed by the line of the 2 nd order phase transition at an intermediate μ B/T, and then by the lines of "higher order transitions" at a low μ B /T. This talk is based on a recent paper (Gorenstein, Gaździcki, and Greiner, 2005).

An electroweak basis for neutrinoless double β decay

Science.gov (United States)

Graesser, Michael L.

2017-08-01

A discovery of neutrinoless double- β decay would be profound, providing the first direct experimental evidence of Δ L = 2 lepton number violating processes. While a natural explanation is provided by an effective Majorana neutrino mass, other new physics interpretations should be carefully evaluated. At low-energies such new physics could man-ifest itself in the form of color and SU(2) L × U(1) Y invariant higher dimension operators. Here we determine a complete set of electroweak invariant dimension-9 operators, and our analysis supersedes those that only impose U(1) em invariance. Imposing electroweak invariance implies: 1) a significantly reduced set of leading order operators compared to only imposing U(1) em invariance; and 2) other collider signatures. Prior to imposing electroweak invariance we find a minimal basis of 24 dimension-9 operators, which is reduced to 11 electroweak invariant operators at leading order in the expansion in the Higgs vacuum expectation value. We set up a systematic analysis of the hadronic realization of the 4-quark operators using chiral perturbation theory, and apply it to determine which of these operators have long-distance pion enhancements at leading order in the chiral expansion. We also find at dimension-11 and dimension-13 the electroweak invariant operators that after electroweak symmetry breaking produce the remaining Δ L = 2 operators that would appear at dimension-9 if only U(1) em is imposed.

Vacuum structure of the electroweak theory in high magnetic fields

International Nuclear Information System (INIS)

Olesen, P.

1991-05-01

In the electroweak theory one can reach the unbroken phase SU(2) x U y (1) by pumping enough magnetic energy into the system. The whole energy is then carried by the fields associated with U y (1), whereas the fields corresponding to SU(2) are in a vacuum state. We show that the vacuum is non-trivial in the sense that it consists of a condensate of zero-field twists which arise in a smooth way from a condensate of vortex lines existing in the broken phase. An explicit vacuum solution is constructed in terms of Weierstrass' elliptic function. (orig.)

Workshop on electroweak symmetry breaking: proceedings

International Nuclear Information System (INIS)

Hinchliffe, I.

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

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.

Integrating out resonances in strongly-coupled electroweak scenarios

Directory of Open Access Journals (Sweden)

Rosell Ignasi

2017-01-01

Full Text Available Accepting that there is a mass gap above the electroweak scale, the Electroweak Effective Theory (EWET is an appropriate tool to describe this situation. Since the EWET couplings contain information on the unknown high-energy dynamics, we consider a generic strongly-coupled scenario of electroweak symmetry breaking, where the known particle fields are coupled to heavier states. Then, and by integrating out these heavy fields, we study the tracks of the lightest resonances into the couplings. The determination of the low-energy couplings (LECs in terms of resonance parameters can be made more precise by considering a proper short-distance behaviour on the Lagrangian with heavy states, since the number of resonance couplings is then reduced. Notice that we adopt a generic non-linear realization of the electroweak symmetry breaking with a singlet Higgs.

Hadronization during quark-gluon plasma phase transition

International Nuclear Information System (INIS)

Mohanty, A.K.; Kataria, S.K.

1996-01-01

The hadron multiplicity distributions and factorial moments are studied in the framework of Landau theory of phase transitions. The factorial moments show a scaling law with a scaling exponent ν which characterizes the intermittency properties of the hadron phase for T c (or T t ) where T c (or T t ) is the transition temperature for second (or first) order transition. The scaling exponent ν is weakly dependent on the free energy parameters as well as on temperature. It is shown that ν remains practically constant in the hadron phase for which T c or T t whether the transition is second order or first order of second kind where the free energy expansion includes cubic term. This universality in the scaling exponent is also maintained above T c over a wide range of temperature even if the transition is strongly first order of first kind where the free energy expansion has only even order coefficients, except around the critical temperature T t where T t approx-gt T c . Therefore, the scaling exponent ν is rather more universal and only indicates the presence of a possible phase transition. It is further shown that the hadron multiplicity distribution is quite sensitive to the free energy parameters. The study of hadron multiplicity distribution at various resolution or bin size reveals more information about the dynamics of the phase transition. The calculated hadron multiplicity distributions are also compared with the negative binomial distribution, often used to explain the experimental multiplicity distributions. copyright 1996 The American Physical Society

EXECUTIVE SUMMARY OF THE SNOWMASS 2001 WORKING GROUP : ELECTROWEAK SYMMETRY BREAKING

International Nuclear Information System (INIS)

CARENA, M.; GERDES, D.W.; HABER, H.E.; TURCOT, A.S.; ZERWAS, P.M.

2001-01-01

In this summary report of the 2001 Snowmass Electroweak Symmetry Breaking Working Group, the main candidates for theories of electroweak symmetry breaking are surveyed, and the criteria for distinguishing among the different approaches are discussed. The potential for observing electroweak symmetry breaking phenomena at the upgraded Tevatron and the LHC is described. We emphasize the importance of a high-luminosity e + e - linear collider for precision measurements to clarify the underlying electroweak symmetry breaking dynamics. Finally, we note the possible roles of the μ + μ - collider and VLHC for further elucidating the physics of electroweak symmetry breaking

Two kinds of phase transitions in a voting model

Science.gov (United States)

Hisakado, M.; Mori, S.

2012-08-01

In this paper, we discuss a voting model with two candidates, C0 and C1. We consider two types of voters—herders and independents. The voting of independents is based on their fundamental values, while the voting of herders is based on the number of previous votes. We can identify two kinds of phase transitions. One is an information cascade transition similar to a phase transition seen in the Ising model. The other is a transition of super and normal diffusions. These phase transitions coexist. We compared our results to the conclusions of experiments and identified the phase transitions in the upper limit of the time t by using the analysis of human behavior obtained from experiments.

Quarks-bags phase transition in quantum chromodynamics

International Nuclear Information System (INIS)

Gorenshtejn, M.I.

1981-01-01

Phase transitions in the quark-gluon plasma are considered at finite temperatures and chemical potentials. A phenomenological account for a complicated structure of the QCD vacuum results in the necessity to use the formalism of isobaric ensembles to describe the system. The phase transition curve separating the regions of the quark-gluon plasma and the hadronic bag phase in the μT plane is calculated [ru

Phase Transitions in Algebraic Cluster Models

International Nuclear Information System (INIS)

Yepez-Martinez, H.; Cseh, J.; Hess, P.O.

2006-01-01

Complete text of publication follows. Phase transitions in nuclear systems are of utmost interest. An interesting class of phase transitions can be seen in algebraic models of nuclear structure. They are called shapephase transitions due to the following reason. These models have analytically solvable limiting cases, called dynamical symmetries, which are characterized by a chain of nested subgroups. They correspond to well-defined geometrical shape and behaviour, e.g. to rotation of an ellipsoid, or spherical vibration. The general case of the model, which includes interactions described by more than one groupchain, breaks the symmetry, and changing the relative strengths of these interactions, one can go from one shape to the other. In doing so a phase-transition can be seen. A phase transition is defined as a discontinuity of some quantity as a function of the control parameter, which gives the relative strength of the interactions of different symmetries. Real phase transitions can take place only in infinite systems, like in the classical limits of these algebraic models, when the particle number N is very large: N → ∞. For finite N the discontinuities are smoothed out, nevertheless, some indications of the phase-transitions can still be there. A controlled way of breaking the dynamical symmetries may reveal another very interesting phenomenon, i.e. the appearance of a quasidynamical (or effective) symmetry. This rather general symmetry-concept of quantum mechanics corresponds to a situation, in which the symmetry-breaking interactions are so strong that the energy-eigenfunctions are not symmetric, i.e. are not basis states of an irreducible representation of the symmetry group, rather they are linear combinations of these basis states. However, they are very special linear combinations in the sense that their coefficients are (approximately) identical for states with different spin values. When this is the case, then the underlying intrinsic state is the

Unconventional transformation of spin Dirac phase across a topological quantum phase transition

Science.gov (United States)

Xu, Su-Yang; Neupane, Madhab; Belopolski, Ilya; Liu, Chang; Alidoust, Nasser; Bian, Guang; Jia, Shuang; Landolt, Gabriel; Slomski, Batosz; Dil, J. Hugo; Shibayev, Pavel P.; Basak, Susmita; Chang, Tay-Rong; Jeng, Horng-Tay; Cava, Robert J.; Lin, Hsin; Bansil, Arun; Hasan, M. Zahid

2015-01-01

The topology of a topological material can be encoded in its surface states. These surface states can only be removed by a bulk topological quantum phase transition into a trivial phase. Here we use photoemission spectroscopy to image the formation of protected surface states in a topological insulator as we chemically tune the system through a topological transition. Surprisingly, we discover an exotic spin-momentum locked, gapped surface state in the trivial phase that shares many important properties with the actual topological surface state in anticipation of the change of topology. Using a spin-resolved measurement, we show that apart from a surface bandgap these states develop spin textures similar to the topological surface states well before the transition. Our results offer a general paradigm for understanding how surface states in topological phases arise from a quantum phase transition and are suggestive for the future realization of Weyl arcs, condensed matter supersymmetry and other fascinating phenomena in the vicinity of a quantum criticality. PMID:25882717

Towards a natural theory of electroweak interactions

Science.gov (United States)

Dobrescu, Bogdan A.

1998-01-01

I study theories of electroweak symmetry breaking that may describe naturally the electromagnetic and weak interactions of the elementary particles observed so far (quarks, leptons and gauge bosons). These theories should explain why the energy scale at which the electroweak symmetry is spontaneously broken (246 GeV), called the 'electroweak scale', is seventeen orders of magnitude smaller than the 'Planck scale', which is associated with the quantum origin of gravity. I discuss first theories where the electroweak symmetry is broken by the dynamics of new strong interactions, naturally producing the hierarchy between the Planck scale and the electroweak scale. I show that in a realistic class of models of this type, the new gauge bosons needed for generating the mass of the heaviest quark have couplings which require a careful adjustment in order to be compatible with experimental data. In the case where the strong dynamics produces a composite spinless particle ('Higgs boson') whose interactions break the electroweak symmetry, I derive an upper bound of 460 GeV on the Higgs boson mass from experimental constraints on processes sensitive to new physics. I also discuss a different type of theory that explains the hierarchy of energy scales, based on a special symmetry, called supersymmetry, which requires the existence of new particles ('superpartners'). No superpartners have been seen in experiments. Therefore, if they exist, they must have masses larger than the particles known so far, implying that supersymmetry is not exact. In the simplest models, supersymmetry breaking is transmitted to the superpartners by standard gauge interactions. I show that all known models of this type are likely to be unacceptable because they do not admit a stable and phenomenologically viable ground state of the universe ('vacuum'). I then construct modified versions of these models that permit viable stable vacua. Also, I present a new model in which supersymmetry breaking is

Quantum trajectory phase transitions in the micromaser.

Science.gov (United States)

Garrahan, Juan P; Armour, Andrew D; Lesanovsky, Igor

2011-08-01

We study the dynamics of the single-atom maser, or micromaser, by means of the recently introduced method of thermodynamics of quantum jump trajectories. We find that the dynamics of the micromaser displays multiple space-time phase transitions, i.e., phase transitions in ensembles of quantum jump trajectories. This rich dynamical phase structure becomes apparent when trajectories are classified by dynamical observables that quantify dynamical activity, such as the number of atoms that have changed state while traversing the cavity. The space-time transitions can be either first order or continuous, and are controlled not just by standard parameters of the micromaser but also by nonequilibrium "counting" fields. We discuss how the dynamical phase behavior relates to the better known stationary-state properties of the micromaser.

An absorbing phase transition from a structured active particle phase

Energy Technology Data Exchange (ETDEWEB)

Lopez, Cristobal [Instituto Mediterraneo de Estudios Avanzados IMEDEA (CSIC-UIB), Campus de la Universidad de las Islas Baleares, E-07122 Palma de Mallorca (Spain); Ramos, Francisco [Departamento de Electromagnetismo y Fisica de la Materia and Instituto de Fisica Teorica y Computacional Carlos I, Facultad de Ciencias, Universidad de Granada, 18071 Granada (Spain); Hernandez-GarcIa, Emilio [Instituto Mediterraneo de Estudios Avanzados IMEDEA (CSIC-UIB), Campus de la Universidad de las Islas Baleares, E-07122 Palma de Mallorca (Spain)

2007-02-14

In this work we study the absorbing state phase transition of a recently introduced model for interacting particles with neighbourhood-dependent reproduction rates. The novelty of the transition is that as soon as the active phase is reached by increasing a control parameter a periodically arranged structure of particle clusters appears. A numerical study in one and two dimensions shows that the system falls into the directed percolation universality class.

Liquid-liquid phase transition in Stillinger-Weber silicon

International Nuclear Information System (INIS)

Beaucage, Philippe; Mousseau, Normand

2005-01-01

It was recently demonstrated that Stillinger-Weber silicon undergoes a liquid-liquid first-order phase transition deep into the supercooled region (Sastry and Angell 2003 Nat. Mater. 2 739). Here we study the effects of perturbations on this phase transition. We show that the order of the liquid-liquid transition changes with negative pressure. We also find that the liquid-liquid transition disappears when the three-body term of the potential is strengthened by as little as 5%. This implies that the details of the potential could affect strongly the nature and even the existence of the liquid-liquid phase

Algebra of strong and electroweak interactions

International Nuclear Information System (INIS)

Bolokhov, S.V.; Vladimirov, Yu.S.

2004-01-01

The algebraic approach to describing the electroweak and strong interactions is considered within the frames of the binary geometrophysics, based on the principles of the Fokker-Feynman direct interparticle interaction theories of the Kaluza-Klein multidimensional geometrical models and the physical structures theory. It is shown that in this approach the electroweak and strong elementary particles interaction through the intermediate vector bosons, are characterized by the subtypes of the algebraic classification of the complex 3 x 3-matrices [ru

paraelectric phase transition

Indian Academy of Sciences (India)

The ferroelectric phase transition is diffuse in nature and broadening of the peak increases with La content. Keywords. PLZT ... Marssi et al (1998) concluded the PLZTs x/65/35 as a model. ∗ ... by analysing field cooled (FC) and zero field cooled (ZFC) dielectric ... material are fitted with universal dielectric behaviour within.

Phase-transition-like behaviour of quantum games

International Nuclear Information System (INIS)

Du Jiangfeng; Li Hui; Xu Xiaodong; Zhou Xianyi; Han Rongdian

2003-01-01

The discontinuous dependence of the properties of a quantum game on its entanglement has been shown to be very much like phase transitions viewed in the entanglement-payoff diagram (J Du et al 2002 Phys. Rev. Lett. 88 137902). In this paper we investigate such phase-transition-like behaviour of quantum games, by suggesting a method which would help to illuminate the origin of such a kind of behaviour. For the particular case of the generalized Prisoners' Dilemma, we find that, for different settings of the numerical values in the payoff table, even though the classical game behaves the same, the quantum game exhibits different and interesting phase-transition-like behaviour

Phase-transition-like behaviour of quantum games

CERN Document Server

Du Jiang Feng; Xu Xiao Dong; Zhou Xian Yi; Han Rong Dian

2003-01-01

The discontinuous dependence of the properties of a quantum game on its entanglement has been shown to be very much like phase transitions viewed in the entanglement-payoff diagram (J Du et al 2002 Phys. Rev. Lett. 88 137902). In this paper we investigate such phase-transition-like behaviour of quantum games, by suggesting a method which would help to illuminate the origin of such a kind of behaviour. For the particular case of the generalized Prisoners' Dilemma, we find that, for different settings of the numerical values in the payoff table, even though the classical game behaves the same, the quantum game exhibits different and interesting phase-transition-like behaviour.

Observation of the Photon-Blockade Breakdown Phase Transition

Directory of Open Access Journals (Sweden)

J. M. Fink

2017-01-01

Full Text Available Nonequilibrium phase transitions exist in damped-driven open quantum systems when the continuous tuning of an external parameter leads to a transition between two robust steady states. In second-order transitions this change is abrupt at a critical point, whereas in first-order transitions the two phases can coexist in a critical hysteresis domain. Here, we report the observation of a first-order dissipative quantum phase transition in a driven circuit quantum electrodynamics system. It takes place when the photon blockade of the driven cavity-atom system is broken by increasing the drive power. The observed experimental signature is a bimodal phase space distribution with varying weights controlled by the drive strength. Our measurements show an improved stabilization of the classical attractors up to the millisecond range when the size of the quantum system is increased from one to three artificial atoms. The formation of such robust pointer states could be used for new quantum measurement schemes or to investigate multiphoton phases of finite-size, nonlinear, open quantum systems.

Nonequilibrium thermodynamic fluctuations and phase transition in black holes

International Nuclear Information System (INIS)

Su, R.; Cai, R.; Yu, P.K.N.

1994-01-01

Landau nonequilibrium fluctuation and phase transition theory is applied to the discussion of the phase transition of black holes. Some second moments of relevant thermodynamical quantities for Kerr-Newman black holes are estimated. A theorem governing the divergence of some second moments and the occurrence of the phase transition in black holes is given

Phase transitions and critical behaviour for charged black holes

International Nuclear Information System (INIS)

Carlip, S; Vaidya, S

2003-01-01

We investigate the thermodynamics of a four-dimensional charged black hole in a finite cavity in asymptotically flat and asymptotically de Sitter spaces. In each case, we find a Hawking-Page-like phase transition between a black hole and a thermal gas very much like the known transition in asymptotically anti-de Sitter space. For a 'supercooled' black hole - a thermodynamically unstable black hole below the critical temperature for the Hawking-Page phase transition - the phase diagram has a line of first-order phase transitions that terminates in a second-order point. For the asymptotically flat case, we calculate the critical exponents at the second-order phase transition and find that they exactly match the known results for a charged black hole in anti-de Sitter space. We find strong evidence for similar phase transitions for the de Sitter black hole as well. Thus many of the thermodynamic features of charged anti-de Sitter black holes do not really depend on asymptotically anti-de Sitter boundary conditions; the thermodynamics of charged black holes is surprisingly universal

Implementation of electroweak corrections in the POWHEG BOX: single W production

CERN Document Server

Barzè, L; Nason, P; Nicrosini, O; Piccinini, F

2012-01-01

We present a fully consistent implementation of electroweak and strong radiative corrections to single W hadroproduction in the POWHEG BOX framework, treating soft and collinear photon emissions on the same ground as coloured parton emissions. This framework can be easily extended to more complex electroweak processes. We describe how next-to-leading order (NLO) electroweak corrections are combined with the NLO QCD calculation, and show how they are interfaced to QCD and QED shower Monte Carlo. The resulting tool fills a gap in the literature and allows to study comprehensively the interplay of QCD and electroweak effects to W production using a single computational framework. Numerical comparisons with the predictions of the electroweak generator HORACE, as well as with existing results on the combination of electroweak and QCD corrections to W production, are shown for the LHC energies, to validate the reliability and accuracy of the approach

A grain boundary phase transition in Si–Au

International Nuclear Information System (INIS)

Ma, Shuailei; Meshinchi Asl, Kaveh; Tansarawiput, Chookiat; Cantwell, Patrick R.; Qi, Minghao; Harmer, Martin P.; Luo, Jian

2012-01-01

A grain boundary transition from a bilayer to an intrinsic (nominally clean) boundary is observed in Si–Au. An atomically abrupt transition between the two complexions (grain boundary stabilized phases) implies the occurrence of a first-order interfacial phase transition associated with a discontinuity in the interfacial excess. This observation supports a grain-boundary complexion theory with broad applications. This transition is atypical in that the monolayer complexion is absent. A model is proposed to explain the bilayer stabilization and the origin of this complexion transition.

Phase Transitions in Geomorphology

Science.gov (United States)

Ortiz, C. P.; Jerolmack, D. J.

2015-12-01

Landscapes are patterns in a dynamic steady-state, due to competing processes that smooth or sharpen features over large distances and times. Geomorphic transport laws have been developed to model the mass-flux due to different processes, but are unreasonably effective at recovering the scaling relations of landscape features. Using a continuum approximation to compare experimental landscapes and the observed landscapes of the earth, one finds they share similar morphodynamics despite a breakdown of classical dynamical similarity between the two. We propose the origin of this effectiveness is a different kind of dynamic similarity in the statistics of initiation and cessation of motion of groups of grains, which is common to disordered systems of grains under external driving. We will show how the existing data of sediment transport points to common signatures with dynamical phase transitions between "mobile" and "immobile" phases in other disordered systems, particularly granular materials, colloids, and foams. Viewing landscape evolution from the lens of non-equilibrium statistical physics of disordered systems leads to predictions that the transition of bulk measurements such as particle flux is continuous from one phase to another, that the collective nature of the particle dynamics leads to very slow aging of bulk properties, and that the dynamics are history-dependent. Recent results from sediment transport experiments support these predictions, suggesting that existing geomorphic transport laws may need to be replaced by a new generation of stochastic models with ingredients based on the physics of disordered phase transitions. We discuss possible strategies for extracting the necessary information to develop these models from measurements of geomorphic transport noise by connecting particle-scale collective dynamics and space-time fluctuations over landscape features.

Searches for Electroweak SUSY by ATLAS and CMS

CERN Document Server

Khoo, Teng Jian; The ATLAS collaboration

2018-01-01

While strongly-produced SUSY and third-generation squark searches have already breached the TeV mass range, direct production of electroweak gauginos is less tightly constrained. New searches are presented, showcasing novel strategies for filling in the gaps in sensitivity to electroweak SUSY at ATLAS and CMS.

Phase transitions in solids under high pressure

CERN Document Server

Blank, Vladimir Davydovich

2013-01-01

Phase equilibria and kinetics of phase transformations under high pressureEquipment and methods for the study of phase transformations in solids at high pressuresPhase transformations of carbon and boron nitride at high pressure and deformation under pressurePhase transitions in Si and Ge at high pressure and deformation under pressurePolymorphic α-ω transformation in titanium, zirconium and zirconium-titanium alloys Phase transformations in iron and its alloys at high pressure Phase transformations in gallium and ceriumOn the possible polymorphic transformations in transition metals under pressurePressure-induced polymorphic transformations in АIBVII compoundsPhase transformations in AIIBVI and AIIIBV semiconductor compoundsEffect of pressure on the kinetics of phase transformations in iron alloysTransformations during deformation at high pressure Effects due to phase transformations at high pressureKinetics and hysteresis in high-temperature polymorphic transformations under pressureHysteresis and kineti...

Late time phase transition as dark energy

Indian Academy of Sciences (India)

Abstract. We show that the dark energy field can naturally be described by the scalar condensates of a non-abelian gauge group. This gauge group is unified with the standard model gauge groups and it has a late time phase transition. The small phase transition explains why the positive acceleration of the universe is ...

Electroweak boson production in Pb+Pb

CERN Document Server

Balestri, T; The ATLAS collaboration

2013-01-01

Lead-lead collisions at the LHC are capable of producing a system of deconfined quarks and gluons at unprecedented energy density and temperature. Partonic-level interactions and energy-loss mechanisms in the medium can be studied with the aid of electroweak bosons which carry important information about the properties of the medium. Electroweak bosons form a class of unique high-$p_{T}$ probes because their decay products do not interact with the strongly-coupled medium, providing a benchmark for a variety of other phenomena measured with strongly interacting particles. The ATLAS experiment measures isolated high-$p_{T}$ photons, W and Z bosons via different decay channels. New analyses of experimental data obtained at the LHC with lead-lead beams at $\\sqrt{s_{NN}}$ = 2.76 TeV. This talk will present a comprehensive study of the scaling properties of electroweak bosons showing linear proportionality of production rates to the nuclear thickness function; rapidity distributions W-decays directly sensitivity to...

Phase separation in the nonequilibrium Verwey transition in magnetite

Science.gov (United States)

Randi, F.; Vergara, I.; Novelli, F.; Esposito, M.; Dell'Angela, M.; Brabers, V. A. M.; Metcalf, P.; Kukreja, R.; Dürr, H. A.; Fausti, D.; Grüninger, M.; Parmigiani, F.

2016-02-01

We present equilibrium and out-of-equilibrium studies of the Verwey transition in magnetite. In the equilibrium optical conductivity, we find a steplike change at the phase transition for photon energies below about 2 eV. The possibility of triggering a nonequilibrium transient metallic state in insulating magnetite by photo excitation was recently demonstrated by an x-ray study. Here we report a full characterization of the optical properties in the visible frequency range across the nonequilibrium phase transition. Our analysis of the spectral features is based on a detailed description of the equilibrium properties. The out-of-equilibrium optical data bear the initial electronic response associated to localized photoexcitation, the occurrence of phase separation, and the transition to a transient metallic phase for excitation density larger than a critical value. This allows us to identify the electronic nature of the transient state, to unveil the phase transition dynamics, and to study the consequences of phase separation on the reflectivity, suggesting a spectroscopic feature that may be generally linked to out-of-equilibrium phase separation.

Liquid-liquid phase transition and glass transition in a monoatomic model system.

Science.gov (United States)

Xu, Limei; Buldyrev, Sergey V; Giovambattista, Nicolas; Stanley, H Eugene

2010-01-01

We review our recent study on the polyamorphism of the liquid and glass states in a monatomic system, a two-scale spherical-symmetric Jagla model with both attractive and repulsive interactions. This potential with a parametrization for which crystallization can be avoided and both the glass transition and the liquid-liquid phase transition are clearly separated, displays water-like anomalies as well as polyamorphism in both liquid and glassy states, providing a unique opportunity to study the interplay between the liquid-liquid phase transition and the glass transition. Our study on a simple model may be useful in understanding recent studies of polyamorphism in metallic glasses.

Liquid-Liquid Phase Transition and Glass Transition in a Monoatomic Model System

Directory of Open Access Journals (Sweden)

Nicolas Giovambattista

2010-12-01

Full Text Available We review our recent study on the polyamorphism of the liquid and glass states in a monatomic system, a two-scale spherical-symmetric Jagla model with both attractive and repulsive interactions. This potential with a parametrization for which crystallization can be avoided and both the glass transition and the liquid-liquid phase transition are clearly separated, displays water-like anomalies as well as polyamorphism in both liquid and glassy states, providing a unique opportunity to study the interplay between the liquid-liquid phase transition and the glass transition. Our study on a simple model may be useful in understanding recent studies of polyamorphism in metallic glasses.

Surface phase transitions in cu-based solid solutions

Science.gov (United States)

Zhevnenko, S. N.; Chernyshikhin, S. V.

2017-11-01

We have measured surface energy in two-component Cu-based systems in H2 + Ar gas atmosphere. The experiments on solid Cu [Ag] and Cu [Co] solutions show presence of phase transitions on the surfaces. Isotherms of the surface energy have singularities (the minimum in the case of copper solid solutions with silver and the maximum in the case of solid solutions with cobalt). In both cases, the surface phase transitions cause deficiency of surface miscibility: formation of a monolayer (multilayer) (Cu-Ag) or of nanoscale particles (Cu-Co). At the same time, according to the volume phase diagrams, the concentration and temperature of the surface phase transitions correspond to the solid solution within the volume. The method permits determining the rate of diffusional creep in addition to the surface energy. The temperature and concentration dependence of the solid solutions' viscosity coefficient supports the fact of the surface phase transitions and provides insights into the diffusion properties of the transforming surfaces.

The infinite limit as an eliminable approximation for phase transitions

Science.gov (United States)

Ardourel, Vincent

2018-05-01

It is generally claimed that infinite idealizations are required for explaining phase transitions within statistical mechanics (e.g. Batterman 2011). Nevertheless, Menon and Callender (2013) have outlined theoretical approaches that describe phase transitions without using the infinite limit. This paper closely investigates one of these approaches, which consists of studying the complex zeros of the partition function (Borrmann et al., 2000). Based on this theory, I argue for the plausibility for eliminating the infinite limit for studying phase transitions. I offer a new account for phase transitions in finite systems, and I argue for the use of the infinite limit as an approximation for studying phase transitions in large systems.

Phase transitions in field theory

International Nuclear Information System (INIS)

Carvalho, C.A.A. de; Bollini, C.G.; Giambiagi, J.J.

1984-01-01

By means of an example for which the effective potential is explicitly calculable (up to the one loop approximation), it is discussed how a phase transition takes place as the temperature is increased and pass from spontaneously broken symmetry to a phase in which the symmetry is restored. (Author) [pt

Sensing of phase transition in medium with terahertz pulsed spectroscopy

International Nuclear Information System (INIS)

Zaytsev, Kirill I; Fokina, Irina N; Fedorov, Aleksey K; Yurchenko, Stanislav O

2014-01-01

Phase state identification and phase transition registration in condensed matter are significant applications of terahertz spectroscopy. A set of fundamental and applied problems are associated with the phase state problem. Our report is devoted to the experimental analysis of the spectral characteristics of water and water solution during the phase transition from the solid state to the liquid state via the method of terahertz pulsed spectroscopy. In this work transformation of the sample spectral characteristics during the phase transition were observed and discussed. Possible application of terahertz pulsed spectroscopy as an effective instrument for phase transition sensing was considered

The electroweak polarization asymmetry: A guided tour

International Nuclear Information System (INIS)

Kennedy, D.C.

1988-10-01

A comprehensive review is provided of the electroweak polarization asymmetry at the Z 0 , a highly accurate measure of the Z 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 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 0 asymmetries. Experimental issues are briefly presented, stressing the importance of polarization at the SLC and LEP e + e - colliders. 42 refs., 13 figs., 2 tabs

Phase transition to QGP matter : confined vs deconfined matter

CERN Multimedia

Maire, Antonin

2015-01-01

Simplified phase diagram of the nuclear phase transition, from the regular hadronic matter to the QGP phase. The sketch is meant to describe the transition foreseen along the temperature axis, at low baryochemical potential, µB.

Exceptional Points and Dynamical Phase Transitions

Directory of Open Access Journals (Sweden)

I. Rotter

2010-01-01

Full Text Available In the framework of non-Hermitian quantum physics, the relation between exceptional points,dynamical phase transitions and the counter intuitive behavior of quantum systems at high level density is considered. The theoretical results obtained for open quantum systems and proven experimentally some years ago on a microwave cavity, may explain environmentally induce deffects (including dynamical phase transitions, which have been observed in various experimental studies. They also agree(qualitatively with the experimental results reported recently in PT symmetric optical lattices.

Two kinds of Phase transitions in a Voting model

OpenAIRE

Hisakado, Masato; Mori, Shintaro

2012-01-01

In this paper, we discuss a voting model with two candidates, C_0 and C_1. We consider two types of voters--herders and independents. The voting of independents is based on their fundamental values; on the other hand, the voting of herders is based on the number of previous votes. We can identify two kinds of phase transitions. One is an information cascade transition similar to a phase transition seen in Ising model. The other is a transition of super and normal diffusions. These phase trans...

Friction forces on phase transition fronts

International Nuclear Information System (INIS)

Mégevand, Ariel

2013-01-01

In cosmological first-order phase transitions, the microscopic interaction of the phase transition fronts with non-equilibrium plasma particles manifests itself macroscopically as friction forces. In general, it is a nontrivial problem to compute these forces, and only two limits have been studied, namely, that of very slow walls and, more recently, ultra-relativistic walls which run away. In this paper we consider ultra-relativistic velocities and show that stationary solutions still exist when the parameters allow the existence of runaway walls. Hence, we discuss the necessary and sufficient conditions for the fronts to actually run away. We also propose a phenomenological model for the friction, which interpolates between the non-relativistic and ultra-relativistic values. Thus, the friction depends on two friction coefficients which can be calculated for specific models. We then study the velocity of phase transition fronts as a function of the friction parameters, the thermodynamic parameters, and the amount of supercooling

Scaling theory and the classification of phase transitions

International Nuclear Information System (INIS)

Hilfer, R.

1992-01-01

In this paper, the recent classification theory for phase transitions and its relation with the foundations of statistical physics is reviewed. First it is outlined how Ehrenfests classification scheme can be generalized into a general thermodynamic classification theory for phase transitions. The classification theory implies scaling and multiscaling thereby eliminating the need to postulate the scaling hypothesis as a fourth law of thermodynamics. The new classification has also led to the discovery and distinction of nonequilibrium transitions within equilibrium statistical physics. Nonequilibrium phase transitions are distinguished from equilibrium transitions by orders less than unity and by the fact the equilibrium thermodynamics and statistical mechanics become inapplicable at the critical point. The latter fact requires a change in the Gibbs assumption underlying the canonical and grandcanonical ensembles in order to recover the thermodynamic description in the critical limit

A perturbative RS I cosmological phase transition

Energy Technology Data Exchange (ETDEWEB)

Bunk, Don [Skidmore College, Department of Physics, Saratoga Springs, NY (United States); Hubisz, Jay [Syracuse University, Department of Physics, Syracuse, NY (United States); Jain, Bithika [Korea Institute for Advanced Study, School of Physics, Seoul (Korea, Republic of)

2018-01-15

We identify a class of Randall-Sundrum type models with a successful first order cosmological phase transition during which a 5D dual of approximate conformal symmetry is spontaneously broken. Our focus is on soft-wall models that naturally realize a light radion/dilaton and suppressed dynamical contribution to the cosmological constant. We discuss phenomenology of the phase transition after developing a theoretical and numerical analysis of these models both at zero and finite temperature. We demonstrate a model with a TeV-Planck hierarchy and with a successful cosmological phase transition where the UV value of the curvature corresponds, via AdS/CFT, to an N of 20, where 5D gravity is expected to be firmly in the perturbative regime. (orig.)

Upper bound on the cutoff in lattice electroweak theory

International Nuclear Information System (INIS)

Veselov, A.I.; Zubkov, M.A.

2008-01-01

We investigate numerically lattice Weinberg-Salam model without fermions for realistic values of the fine structure constant and the Weinberg angle. We also analyze the data of the previous numerical investigations of lattice Electroweak theory. We have found that moving along the line of constant physics when the lattice spacing a is decreased, one should leave the physical Higgs phase of the theory at a certain value of a. Our estimate of the minimal value of the lattice spacing is a c = [430 ± 40 GeV] -1 .

First-principles study of doping effect on the phase transition of zinc oxide with transition metal doped

International Nuclear Information System (INIS)

Wu, Liang; Hou, Tingjun; Wang, Yi; Zhao, Yanfei; Guo, Zhenyu; Li, Youyong; Lee, Shuit-Tong

2012-01-01

Highlights: ► We study the doping effect on B4, B1 structures and phase transition of ZnO. ► We calculate the phase transition barrier and phase transition path of doped ZnO. ► The transition metal doping decreases the bulk modulus and phase transition pressure. ► The magnetic properties are influenced by the phase transition process. - Abstract: Zinc oxide (ZnO) is a promising material for its wide application in solid-state devices. With the pressure raised from an ambient condition, ZnO transforms from fourfold wurtzite (B4) to sixfold coordinated rocksalt (B1) structure. Doping is an efficient approach to improve the structures and properties of materials. Here we use density-functional theory (DFT) to study doped ZnO and find that the transition pressure from B4 phase to B1 phase of ZnO always decreases with different types of transition metal (V, Cr, Mn, Fe, Co, or Ni) doped, but the phase transition path is not affected by doping. This is consistent with the available experimental results for Mn-doped ZnO and Co-doped ZnO. Doping in ZnO causes the lattice distortion, which leads to the decrease of the bulk modulus and accelerates the phase transition. Mn-doped ZnO shows the strongest magnetic moment due to its half filled d orbital. For V-doped ZnO and Cr-doped ZnO, the magnetism is enhanced by phase transition from B4 to B1. But for Mn-doped ZnO, Fe-doped ZnO, Co-doped ZnO, and Ni-doped ZnO, B1 phase shows weaker magnetic moment than B4 phase. These results can be explained by the amount of charge transferred from the doped atom to O atom. Our results provide a theoretical basis for the doping approach to change the structures and properties of ZnO.

A Bayesian Interpretation of First-Order Phase Transitions

Science.gov (United States)

Davis, Sergio; Peralta, Joaquín; Navarrete, Yasmín; González, Diego; Gutiérrez, Gonzalo

2016-03-01

In this work we review the formalism used in describing the thermodynamics of first-order phase transitions from the point of view of maximum entropy inference. We present the concepts of transition temperature, latent heat and entropy difference between phases as emergent from the more fundamental concept of internal energy, after a statistical inference analysis. We explicitly demonstrate this point of view by making inferences on a simple game, resulting in the same formalism as in thermodynamical phase transitions. We show that analogous quantities will inevitably arise in any problem of inferring the result of a yes/no question, given two different states of knowledge and information in the form of expectation values. This exposition may help to clarify the role of these thermodynamical quantities in the context of different first-order phase transitions such as the case of magnetic Hamiltonians (e.g. the Potts model).

Fingerprints of heavy scales in electroweak effective Lagrangians

Science.gov (United States)

Pich, Antonio; Rosell, Ignasi; Santos, Joaquín; Sanz-Cillero, Juan José

2017-04-01

The couplings of the electroweak effective theory contain information on the heavy-mass scales which are no-longer present in the low-energy Lagrangian. We build a general effective Lagrangian, implementing the electroweak chiral symmetry breaking SU(2) L ⊗ SU(2) R → SU(2) L+ R , which couples the known particle fields to heavier states with bosonic quantum numbers J P = 0± and 1±. We consider colour-singlet heavy fields that are in singlet or triplet representations of the electroweak group. Integrating out these heavy scales, we analyze the pattern of low-energy couplings among the light fields which are generated by the massive states. We adopt a generic non-linear realization of the electroweak symmetry breaking with a singlet Higgs, without making any assumption about its possible doublet structure. Special attention is given to the different possible descriptions of massive spin-1 fields and the differences arising from naive implementations of these formalisms, showing their full equivalence once a proper short-distance behaviour is required.

Fingerprints of heavy scales in electroweak effective Lagrangians

Energy Technology Data Exchange (ETDEWEB)

Pich, Antonio [Departament de Física Teòrica, IFIC, Universitat de València - CSIC,Apt. Correus 22085, E-46071 València (Spain); Rosell, Ignasi [Departamento de Matemáticas, Física y Ciencias Tecnológicas,Universidad CEU Cardenal Herrera, E-46115 Alfara del Patriarca, València (Spain); Santos, Joaquín [Departament de Física Teòrica, IFIC, Universitat de València - CSIC,Apt. Correus 22085, E-46071 València (Spain); Sanz-Cillero, Juan José [Departamento de Física Teórica I, Universidad Complutense de Madrid,E-28040 Madrid (Spain)

2017-04-04

The couplings of the electroweak effective theory contain information on the heavy-mass scales which are no-longer present in the low-energy Lagrangian. We build a general effective Lagrangian, implementing the electroweak chiral symmetry breaking SU(2){sub L}⊗SU(2){sub R}→SU(2){sub L+R}, which couples the known particle fields to heavier states with bosonic quantum numbers J{sup P}=0{sup ±} and 1{sup ±}. We consider colour-singlet heavy fields that are in singlet or triplet representations of the electroweak group. Integrating out these heavy scales, we analyze the pattern of low-energy couplings among the light fields which are generated by the massive states. We adopt a generic non-linear realization of the electroweak symmetry breaking with a singlet Higgs, without making any assumption about its possible doublet structure. Special attention is given to the different possible descriptions of massive spin-1 fields and the differences arising from naive implementations of these formalisms, showing their full equivalence once a proper short-distance behaviour is required.

Bubble nucleation and growth in very strong cosmological phase transitions

Energy Technology Data Exchange (ETDEWEB)

Mégevand, Ariel, E-mail: megevand@mdp.edu.ar; Ramírez, Santiago

2017-06-15

Strongly first-order phase transitions, i.e., those with a large order parameter, are characterized by a considerable supercooling and high velocities of phase transition fronts. A very strong phase transition may have important cosmological consequences due to the departures from equilibrium caused in the plasma. In general, there is a limit to the strength, since the metastability of the old phase may prevent the transition to complete. Near this limit, the bubble nucleation rate achieves a maximum and thus departs from the widely assumed behavior in which it grows exponentially with time. We study the dynamics of this kind of phase transitions. We show that in some cases a gaussian approximation for the nucleation rate is more suitable, and in such a case we solve analytically the evolution of the phase transition. We compare the gaussian and exponential approximations with realistic cases and we determine their ranges of validity. We also discuss the implications for cosmic remnants such as gravitational waves.

On the Possible Links Between Electroweak Symmetry Breaking and Dark Matter

International Nuclear Information System (INIS)

Hambye, Thomas; Tytgat, Michel H. G.

2009-01-01

The mechanism behind electroweak symmetry breaking (EWSB) and the nature of dark matter (DM) are currently very important issues in particle physics. Usually, in most models, these two issues are not or poorly connected. However, since a natural dark matter candidate is a weakly interacting massive particle or WIMP, with mass around the electroweak scale, it is clearly of interest to investigate the possibility that DM and EWSB are closely related. In the context of a very simple extension of the Standard Model, the Inert Doublet Model, we show that dark matter could play a crucial role in the breaking of the electroweak symmetry. In this model, dark matter is the lightest component of an inert scalar doublet which can induce dynamically electroweak symmetry breaking at one loop level. Moreover, in a large fraction of the parameter space of this model, the mass of the dark matter particle is essentially determined by the electroweak scale, so that the fact that the WIMP DM mass is around the electroweak scale is not a coincidence.

Reconstructive structural phase transitions in dense Mg

International Nuclear Information System (INIS)

Yao Yansun; Klug, Dennis D

2012-01-01

The question raised recently about whether the high-pressure phase transitions of Mg follow a hexagonal close-packed (hcp) → body centered cubic (bcc) or hcp → double hexagonal close-packed (dhcp) → bcc sequence at room temperature is examined by the use of first principles density functional methods. Enthalpy calculations show that the bcc structure replaces the hcp structure to become the most stable structure near 48 GPa, whereas the dhcp structure is never the most stable structure in the pressure range of interest. The characterized phase-transition mechanisms indicate that the hcp → dhcp transition is also associated with a higher enthalpy barrier. At room temperature, the structural sequence hcp → bcc is therefore more energetically favorable for Mg. The same conclusion is also reached from the simulations of the phase transitions using metadynamics methods. At room temperature, the metadynamics simulations predict the onset of a hcp → bcc transition at 40 GPa and the transition becomes more prominent upon further compression. At high temperatures, the metadynamics simulations reveal a structural fluctuation among the hcp, dhcp, and bcc structures at 15 GPa. With increasing pressure, the structural evolution at high temperatures becomes more unambiguous and eventually settles to a bcc structure once sufficient pressure is applied. (paper)

A Solvable Model for Nuclear Shape Phase Transitions

International Nuclear Information System (INIS)

Levai, G.; Arias, J. M.

2009-01-01

There has been considerable interest recently in phase transitions that occur between some well-defined nuclear shapes, e.g. the spherical vibrator, the axially deformed rotor and the γ-unstable rotor, which are assigned to the U(5), SU(3) and 0(6) symmetries. These shape phase transitions occur through critical points of the IBM phase diagram and correspond to rapid structural changes. The first transition of this type describes transition form the spherical to the γ-unstable phase and has been associated with an E(5) symmetry. Later further critical point symmetries e.g. X(5) and Y(5) have also been proposed for transitions between other nuclear shape phases. In another application the chain of even Ru isotopes was considered from A 98 to 112 [2]. The parameters were extracted from a fit to the low-lying energy spectrum of each nucleus and were used to plot the corresponding potential. It was found that up to A =102 the potential is essentially an harmonic oscillator, while at A =104 a rather flat potential was seen, in accordance with the expected phase transition and E(5) symmetry there. With increasing A then the minimum got increasingly deeper and moved away from β = 0. We discuss the possibility of generalizing the formalism in two ways: first by including dependence on the 7 variable allowing for the approximate description of nuclei close to the X(5) symmetry, and second, including higher-lying energy levels in the quasi-exactly solvable formalism

Combined QCD and electroweak analysis of HERA data

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max-Planck-Institute for Physics, Munich (Germany); Abt, I. [Max-Planck-Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science; Collaboration: ZEUS Collaboration; and others

2016-03-15

A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.

Combined QCD and electroweak analysis of HERA data

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2016-03-01

A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.

Combined QCD and electroweak analysis of HERA data

CERN Document Server

Abramowicz, H; Adamczyk, L; Adamus, M; Antonelli, S; Aushev, V; Behnke, O; Behrens, U; Bertolin, A; Bloch, I; Boos, EG; Brock, I; Brook, NH; Brugnera, R; Bruni, A; Bussey, PJ; Caldwell, A; Capua, M; Catterall, CD; Chwastowski, J; Ciborowski, J; Ciesielski, R; Cooper-Sarkar, AM; Corradi, M; Dementiev, RK; Devenish, RCE; Dusini, S; Foster, B; Gach, G; Gallo, E; Garfagnini, A; Geiser, A; Gizhko, A; Gladilin, LK; Golubkov, Yu A; Grzelak, G; Guzik, M; Hain, W; Hochman, D; Hori, R; Ibrahim, ZA; Iga, Y; Ishitsuka, M; Januschek, F; Jomhari, NZ; Kadenko, I; Kananov, S; Karshon, U; Kaur, P; Kisielewska, D; Klanner, R; Klein, U; Korzhavina, IA; Kotański, A; Kötz, U; Kovalchuk, N; Kowalski, H; Krupa, B; Kuprash, O; Kuze, M; Levchenko, BB; Levy, A; Limentani, S; Lisovyi, M; Lobodzinska, E; Löhr, B; Lohrmann, E; Longhin, A; Lontkovskyi, D; Lukina, OYu; Makarenko, I; Malka, J; Mohamad Idris, F; Mohammad Nasir, N; Myronenko, V; Nagano, K; Nobe, T; Nowak, RJ; Onishchuk, Yu; Paul, E; Perlański, W; Pokrovskiy, NS; Przybycien, M; Roloff, P; Ruspa, M; Saxon, DH; Schioppa, M; Schneekloth, U; Schörner-Sadenius, T; Shcheglova, LM; Shevchenko, R; Shkola, O; Shyrma, Yu; Singh, I; Skillicorn, IO; Słomiński, W; Solano, A; Stanco, L; Stefaniuk, N; Stern, A; Stopa, P; Sztuk-Dambietz, J; Tassi, E; Tokushuku, K; Tomaszewska, J; Tsurugai, T; Turcato, M; Turkot, O; Tymieniecka, T; Verbytskyi, A; Wan Abdullah, WAT; Wichmann, K; Wing, M; Yamada, S; Yamazaki, Y; Zakharchuk, N; Żarnecki, AF; Zawiejski, L; Zenaiev, O; Zhautykov, BO; Zotkin, DS; Bhadra, S; Gwenlan, C; Hlushchenko, O; Polini, A; Mastroberardino, A

2016-05-03

A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.

Strong Electroweak Symmetry Breaking and Spin-0 Resonances

International Nuclear Information System (INIS)

Evans, Jared; Luty, Markus A.

2009-01-01

We argue that theories of the strong electroweak symmetry breaking sector necessarily contain new spin 0 states at the TeV scale in the tt and tb/bt channels, even if the third generation quarks are not composite at the TeV scale. These states couple sufficiently strongly to third generation quarks to have significant production at LHC via gg→φ 0 or gb→tφ - . The existence of narrow resonances in QCD suggests that the strong electroweak breaking sector contains narrow resonances that decay to tt or tb/bt, with potentially significant branching fractions to 3 or more longitudinal W and Z bosons. These may give new 'smoking gun' signals of strong electroweak symmetry breaking.

Quantum Phase Transition and Entanglement in Topological Quantum Wires.

Science.gov (United States)

Cho, Jaeyoon; Kim, Kun Woo

2017-06-05

We investigate the quantum phase transition of the Su-Schrieffer-Heeger (SSH) model by inspecting the two-site entanglements in the ground state. It is shown that the topological phase transition of the SSH model is signified by a nonanalyticity of local entanglement, which becomes discontinuous for finite even system sizes, and that this nonanalyticity has a topological origin. Such a peculiar singularity has a universal nature in one-dimensional topological phase transitions of noninteracting fermions. We make this clearer by pointing out that an analogous quantity in the Kitaev chain exhibiting the identical nonanalyticity is the local electron density. As a byproduct, we show that there exists a different type of phase transition, whereby the pattern of the two-site entanglements undergoes a sudden change. This transition is characterised solely by quantum information theory and does not accompany the closure of the spectral gap. We analyse the scaling behaviours of the entanglement in the vicinities of the transition points.

High-pressure phase transition of alkali metal-transition metal deuteride Li2PdD2

Science.gov (United States)

Yao, Yansun; Stavrou, Elissaios; Goncharov, Alexander F.; Majumdar, Arnab; Wang, Hui; Prakapenka, Vitali B.; Epshteyn, Albert; Purdy, Andrew P.

2017-06-01

A combined theoretical and experimental study of lithium palladium deuteride (Li2PdD2) subjected to pressures up to 50 GPa reveals one structural phase transition near 10 GPa, detected by synchrotron powder x-ray diffraction, and metadynamics simulations. The ambient-pressure tetragonal phase of Li2PdD2 transforms into a monoclinic C2/m phase that is distinct from all known structures of alkali metal-transition metal hydrides/deuterides. The structure of the high-pressure phase was characterized using ab initio computational techniques and from refinement of the powder x-ray diffraction data. In the high-pressure phase, the PdD2 complexes lose molecular integrity and are fused to extended [PdD2]∞ chains. The discovered phase transition and new structure are relevant to the possible hydrogen storage application of Li2PdD2 and alkali metal-transition metal hydrides in general.

Phenomenology of cosmic phase transitions

International Nuclear Information System (INIS)

Kaempfer, B.; Lukacs, B.; Paal, G.

1989-11-01

The evolution of the cosmic matter from Planck temperature to the atomic combination temperature is considered from a phenomenological point of view. Particular emphasis is devoted to the sequence of cosmic phase transitions. The inflationary era at the temperature of the order of the grand unification energy scale and the quantum chromodynamic confinement transition are dealt with in detail. (author) 131 refs.; 26 figs

Notes on Phase Transition of Nonsingular Black Hole

International Nuclear Information System (INIS)

Ma Meng-Sen; Zhao Ren

2015-01-01

On the belief that a black hole is a thermodynamic system, we study the phase transition of nonsingular black holes. If the black hole entropy takes the form of the Bekenstein—Hawking area law, the black hole mass M is no longer the internal energy of the black hole thermodynamic system. Using the thermodynamic quantities, we calculate the heat capacity, thermodynamic curvature and free energy. It is shown that there will be a larger black hole/smaller black hole phase transition for the nonsingular black hole. At the critical point, the second-order phase transition appears. (paper)

Novel phase transitions in B-site doped manganites

International Nuclear Information System (INIS)

Popovic, Z.V.; Cantarero, A.; Thijssen, W.H.A.; Paunovic, N.; Dohcevic-Mitrovic, Z.; Sapina, F.

2005-01-01

We have examined the infrared reflectivity and the electrical resistivity of La 1- x [Sr(Ba)] x Mn 1- z [Cu(Zn)] z O 3 samples in ferromagnetic metallic and insulator regime. Several phase transitions are observed, the most obvious being the transition from a ferromagnetic metallic to a ferromagnetic insulator phase that is related to the formation of short-range orbitally ordered domains. The temperature T 1 of the phase transition is dependent on doping concentration and for optimally doped samples (∼32% of Mn 4+ ions) we have found T 1 ∼0.93 T C

Baryogenesis via leptonic CP-violating phase transition

Science.gov (United States)

Pascoli, Silvia; Turner, Jessica; Zhou, Ye-Ling

2018-05-01

We propose a new mechanism to generate a lepton asymmetry based on the vacuum CP-violating phase transition (CPPT). This approach differs from classical thermal leptogenesis as a specific seesaw model, and its UV completion, need not be specified. The lepton asymmetry is generated via the dynamically realised coupling of the Weinberg operator during the phase transition. This mechanism provides a connection with low-energy neutrino observables.

High-pressure phase transitions - Examples of classical predictability

Science.gov (United States)

Celebonovic, Vladan

1992-09-01

The applicability of the Savic and Kasanin (1962-1967) classical theory of dense matter to laboratory experiments requiring estimates of high-pressure phase transitions was examined by determining phase transition pressures for a set of 19 chemical substances (including elements, hydrocarbons, metal oxides, and salts) for which experimental data were available. A comparison between experimental and transition points and those predicted by the Savic-Kasanin theory showed that the theory can be used for estimating values of transition pressures. The results also support conclusions obtained in previous astronomical applications of the Savic-Kasanin theory.

Phase transitions in K-doped MoO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Alves, L. M. S., E-mail: leandro-fisico@hotmail.com; Lima, B. S. de; Santos, C. A. M. dos [Departamento de Engenharia de Materiais, Escola de Engenharia de Lorena-USP, Lorena, São Paulo 12602-810 (Brazil); Rebello, A.; Masunaga, S. H.; Neumeier, J. J. [Department of Physics, Montana State University, P.O. Box 173840, Bozeman, Montana 59717-3840 (United States); Leão, J. B. [NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Dr. MS 6102, Gaithersburg, Maryland 20899-6102 (United States)

2014-05-28

K{sub 0.05}MoO{sub 2} has been studied by x-ray and neutron diffractometry, electrical resistivity, magnetization, heat capacity, and thermal expansion measurements. The compound displays two phase transitions, a first-order phase transition near room temperature and a second-order transition near 54 K. Below the transition at 54 K, a weak magnetic anomaly is observed and the electrical resistivity is well described by a power-law temperature dependence with exponent near 0.5. The phase transitions in the K-doped MoO{sub 2} compound have been discussed for the first time using neutron diffraction, high resolution thermal expansion, and heat capacity measurements as a function of temperature.

Phase transition signals of finite systems

International Nuclear Information System (INIS)

Duflot-Flandrois, Veronique

2001-01-01

Phase transitions are universal properties of interacting matter. They are well described if the considered system is infinite, by using standard thermodynamics. But in the case of small systems like atomic nuclei, this formalism cannot be applied anymore. Our aim is to propose a statistical mechanics approach in order to define the thermodynamical features of small open systems subject to non-saturating forces. We concentrate in particular on the definition and characterization for such systems of phase transitions belonging to the liquid gas universality class. Theoretical and experimental observables are defined to signal the occurrence and the order of this transition without any ambiguity. One of the most relevant and experimentally accessible observables consists in the study of kinetic energy fluctuations for a fixed value of the total deposited energy. In a first order phase transition such fluctuations become anomaly high and at the same time the size distribution appears to behave critically. All our results are obtained within numerical simulations of the lattice gas model with a nearest neighbors attractive interaction. Finally we check the influence of non-saturating forces, developing the specific example of the Coulomb interaction in the nucleus. Future improvements and perspectives at this work consist in the analysis of specific effects occurring in nuclei: isospin and quantum mechanics. (author) [fr

Analyzing phase diagrams and phase transitions in networked competing populations

Science.gov (United States)

Ni, Y.-C.; Yin, H. P.; Xu, C.; Hui, P. M.

2011-03-01

Phase diagrams exhibiting the extent of cooperation in an evolutionary snowdrift game implemented in different networks are studied in detail. We invoke two independent payoff parameters, unlike a single payoff often used in most previous works that restricts the two payoffs to vary in a correlated way. In addition to the phase transition points when a single payoff parameter is used, phase boundaries separating homogeneous phases consisting of agents using the same strategy and a mixed phase consisting of agents using different strategies are found. Analytic expressions of the phase boundaries are obtained by invoking the ideas of the last surviving patterns and the relative alignments of the spectra of payoff values to agents using different strategies. In a Watts-Strogatz regular network, there exists a re-entrant phenomenon in which the system goes from a homogeneous phase into a mixed phase and re-enters the homogeneous phase as one of the two payoff parameters is varied. The non-trivial phase diagram accompanying this re-entrant phenomenon is quantitatively analyzed. The effects of noise and cooperation in randomly rewired Watts-Strogatz networks are also studied. The transition between a mixed phase and a homogeneous phase is identify to belong to the directed percolation universality class. The methods used in the present work are applicable to a wide range of problems in competing populations of networked agents.

Solid-solid phase transitions in Fe nanowires induced by axial strain

International Nuclear Information System (INIS)

Sandoval, Luis; Urbassek, Herbert M

2009-01-01

By means of classical molecular-dynamics simulations we investigate the solid-solid phase transition from a bcc to a close-packed crystal structure in cylindrical iron nanowires, induced by axial strain. The interatomic potential employed has been shown to be capable of describing the martensite-austenite phase transition in iron. We study the stress versus strain curves for different temperatures and show that for a range of temperatures it is possible to induce a solid-solid phase transition by axial strain before the elasticity is lost; these transition temperatures are below the bulk transition temperature. The two phases have different (non-linear) elastic behavior: the bcc phase softens, while the close-packed phase stiffens with temperature. We also consider the reversibility of the transformation in the elastic regimes, and the role of the strain rate on the critical strain necessary for phase transition.

Energy helps accuracy: electroweak precision tests at hadron colliders

CERN Document Server

Farina, Marco

2017-09-10

We show that high energy measurements of Drell-Yan at the LHC can serve as electroweak precision tests. Dimension-6 operators, from the Standard Model Effective Field Theory, modify the high energy behavior of electroweak gauge boson propagators. Existing measurements of the dilepton invariant mass spectrum, from neutral current Drell-Yan at 8 TeV, have comparable sensitivity to LEP. We propose measuring the transverse mass spectrum of charged current Drell-Yan, which can surpass LEP already with 8 TeV data. The 13 TeV LHC will elevate electroweak tests to a new precision frontier.

Energy helps accuracy: Electroweak precision tests at hadron colliders

Directory of Open Access Journals (Sweden)

Marco Farina

2017-09-01

Full Text Available We show that high energy measurements of Drell–Yan at the LHC can serve as electroweak precision tests. Dimension-6 operators, from the Standard Model Effective Field Theory, modify the high energy behavior of electroweak gauge boson propagators. Existing measurements of the dilepton invariant mass spectrum, from neutral current Drell–Yan at 8 TeV, have comparable sensitivity to LEP. We propose measuring the transverse mass spectrum of charged current Drell–Yan, which can surpass LEP already with 8 TeV data. The 13 TeV LHC will elevate electroweak tests to a new precision frontier.

A practical introduction to electroweak radiative corrections

International Nuclear Information System (INIS)

Drees, M.

1991-05-01

This is a brief introduction into electroweak radiative corrections within the Standard Model, with the emphasis on performing actual calculations. To this end, a complete set of expressions is given that allows the computation of the ρ parameter, the W mass, and Z→fanti f decays for massless fermions, where the anti Manti S scheme has been used. I conclude with an assessment of what we have learned so far from electroweak precision experiments, and a brief outlook. (orig.)

3-3-1 models at electroweak scale

International Nuclear Information System (INIS)

Dias, Alex G.; Montero, J.C.; Pleitez, V.

2006-01-01

We show that in 3-3-1 models there exist a natural relation among the SU(3) L coupling constant g, the electroweak mixing angle θ W , the mass of the W, and one of the vacuum expectation values, which implies that those models can be realized at low energy scales and, in particular, even at the electroweak scale. So that, being that symmetries realized in Nature, new physics may be really just around the corner

Electroweak boson production with jets at CMS

CERN Document Server

Hortiangtham, Apichart

2017-01-01

The production of electroweak bosons (W, Z or gamma) in association with jets is a stringent test of perturbative QCD and is a background process in searches for new physics. Total and differential cross-section measurements of electroweak bosons produced in association with jets (and heavy flavour quarks) in proton-proton collisions are presented. The data have been recorded with the CMS detector at the LHC and are compared to the predictions of event generators and theoretical calculations.

Diffusionless phase transitions and related structures in oxides

International Nuclear Information System (INIS)

Boulesteix, C.

1992-01-01

The relative importance of oxides in the field of materials science has been spectacularly increasing during the last twenty years. First the study of ferroelectrics kept the attention of scientists. Nevertheless this domain is far from being worked out and a lot of new results and of new fields of interest were recently discovered. Other ferroic oxides, especially ferroelastics, have also been the subject of a very great number of new results. In these cases the properties of oxides are at room temperature very tightly related to the phase transition that is generally occurring a few hundred of degrees above this room temperature. In many other cases also properties of oxides can be related to the existence of a phase transition or to a rather similar phenomenon. This book has been specially devoted to the study of the properties of oxides which are in some way related to the existence of a phase transition. The first chapters are focussed on general considerations: the first one is devoted to a general study of phase transitions, the second one to the twinning phenomenon which is of special interest for many oxides. Chapters 3 and 4 are focussed on ferroelectric and ferroelastic materials. These four chapters consitute the first part of the book. Chapters 5 to 8 are devoted to the study of oxides of special interest which have some of their properties related to a phase transition or to a rather similar phenomenon: rare earth oxides, oxides with a diffuse phase transition, zirconia and alumina systems, tungsten oxides and their relatives. These four chapters constitute the second part of the book. (orig.)

Supersymmetric electro-weak effects on gsub(μ)-2

International Nuclear Information System (INIS)

Yuan, T.C.; Arnowitt, R.; Chamseddine, A.H.; Nath, P.

1984-01-01

A model independent analysis of the supersymmetric electroweak contribution to gsub(μ)-2 is discussed within the framework of N=1 Supergravity unified theory. A detailed comparison with existing experiment of two models (R.G. and T.B.) is carried out. The supersymmetric electro-weak contributions are found to be characteristically different and generally larger than the electro-weak contributions of the standard theory, and in many cases significantly larger. Effects of the hidden sector and the photino mass dependence of gsub(μ)-2 are also investigated. Present data already eliminates some choices of parameters. Reduction of existing experimental errors by a factor of 3 will make contact with most R.G. models and by a factor of 10 with most T.B. models. (orig.)

Discontinuous structural phase transition of liquid metal and alloys (2)

International Nuclear Information System (INIS)

Wang, Li; Liu, Jiantong

2004-01-01

The diameter (d f ) of diffusion fluid cluster before and after phase transition has been calculated in terms of the paper ''Discontinuous structural phase transition of liquid metal and alloy (1)'' Physics Letters. A 326 (2004) 429-435, to verify quantitatively the discontinuity of structural phase transition; the phenomena of thermal contraction and thermal expansion during the phase transition, together with the evolution model of discontinuous structural phase transition are also discussed in this Letter to explore further the nature of structural transition; In addition, based on the viscosity experimental result mentioned in paper [Y. Waseda, The Structure of Non-Crystalline Materials--Liquids and Amorphous Solids, McGraw-Hill, New York, 1980], we present an approach to draw an embryo of the liquid-liquid (L-L) phase diagram for binary alloys above liquidus in the paper, expecting to guide metallurgy process so as to improve the properties of alloys. The idea that controls amorphous structure and its properties by means of the L-L phase diagram for alloys and by the rapid cooling technique to form the amorphous alloy has been brought forward in the end

Dimension changing phase transitions in instanton crystals

International Nuclear Information System (INIS)

Kaplunovsky, Vadim; Sonnenschein, Jacob

2014-01-01

We investigate lattices of instantons and the dimension-changing transitions between them. Our ultimate goal is the 3D→4D transition, which is holographically dual to the phase transition between the baryonic and the quarkyonic phases of cold nuclear matter. However, in this paper (just as in http://dx.doi.org/10.1007/JHEP11(2012)047) we focus on lower dimensions — the 1D lattice of instantons in a harmonic potential V∝M 2 2 x 2 2 +M 3 2 x 2 2 +M 4 2 x 4 2 , and the zigzag-shaped lattice as a first stage of the 1D→2D transition. We prove that in the low- and moderate-density regimes, interactions between the instantons are dominated by two-body forces. This drastically simplifies finding the ground state of the instantons’ orientations, so we made a numeric scan of the whole orientation space instead of assuming any particular ansatz. We find that depending on the M 2 /M 3 /M 4 ratios, the ground state of instanton orientations can follow a wide variety of patterns. For the straight 1D lattices, we found orientations periodically running over elements of a ℤ 2 , Klein, prismatic, or dihedral subgroup of the SU(2)/ℤ 2 , as well as irrational but link-periodic patterns. For the zigzag-shaped lattices, we detected 4 distinct orientation phases — the anti-ferromagnet, another abelian phase, and two non-abelian phases. Allowing the zigzag amplitude to vary as a function of increasing compression force, we obtained the phase diagrams for the straight and zigzag-shaped lattices in the (force,M 3 /M 4 ), (chemical potential,M 3 /M 4 ), and (density,M 3 /M 4 ) planes. Some of the transitions between these phases are second-order while others are first-order. Our techniques can be applied to other types of non-abelian crystals

Novel phase transitions in B-site doped manganites

Energy Technology Data Exchange (ETDEWEB)

Popovic, Z.V. [Institute of Physics, P.O. Box 68, 11080 Belgrade/Zemun (Serbia and Montenegro)]. E-mail: zoran.popovic@phy.bg.ac.yu; Cantarero, A. [Materials Science Institute, University of Valencia, P.O. Box 22085, 46071 Valencia (Spain); Thijssen, W.H.A. [Kamerlingh Onnes Laboratorium, Leiden University, Postbus 9504, 2300 RA Leiden (Netherlands); Paunovic, N. [Institute of Physics, P.O. Box 68, 11080 Belgrade/Zemun (Serbia and Montenegro); Dohcevic-Mitrovic, Z. [Institute of Physics, P.O. Box 68, 11080 Belgrade/Zemun (Serbia and Montenegro); Sapina, F. [Materials Science Institute, University of Valencia, P.O. Box 22085, 46071 Valencia (Spain)

2005-04-30

We have examined the infrared reflectivity and the electrical resistivity of La{sub 1-} {sub x} [Sr(Ba)] {sub x} Mn{sub 1-} {sub z} [Cu(Zn)] {sub z} O{sub 3} samples in ferromagnetic metallic and insulator regime. Several phase transitions are observed, the most obvious being the transition from a ferromagnetic metallic to a ferromagnetic insulator phase that is related to the formation of short-range orbitally ordered domains. The temperature T {sub 1} of the phase transition is dependent on doping concentration and for optimally doped samples ({approx}32% of Mn{sup 4+} ions) we have found T {sub 1}{approx}0.93 T {sub C}.

Conformal dynamics for electroweak symmetry breaking, from LHC to cosmology

International Nuclear Information System (INIS)

Sannino, Francesco

2009-01-01

Full text. I will first introduce dynamical electroweak symmetry breaking and then present how to resolve some of the long-standing problems using (near) conformal dynamics. In order to construct sensible extension of DEWSB I will then review the state-of-the-art of the phase diagram of gauge theories of fundamental interactions as function of the number of colors, flavors and matter representation. Finally I will introduce recent models known as minimal walking models and show how they lead to natural candidates of dark matter. (author)

Baryon inhomogeneity from the cosmic quark-hadron phase transition

International Nuclear Information System (INIS)

Kurki-Suonio, H.

1991-01-01

We discuss the generation of inhomogeneity in the baryon-number density during the cosmic quark-hadron phase transition. We use a simple model with thin-wall phase boundaries and ideal-gas equations of state. The nucleation of the phase transition introduces a new distance scale into the universe which will be the scale of the generated inhomogeneity. We review the estimate of this scale. During the transition baryon number is likely to collect onto a layer at the phase boundary. These layers may in the end be deposited as small regions of very high baryon density. 21 refs., 1 fig

Holographic theories of electroweak symmetry breaking without a Higgs Boson

International Nuclear Information System (INIS)

Burdman, Gustavo; Nomura, Yasunori

2003-01-01

Recently, realistic theories of electroweak symmetry breaking have been constructed in which the electroweak symmetry is broken by boundary conditions imposed at a boundary of higher dimensional spacetime. These theories have equivalent 4D dual descriptions, in which the electroweak symmetry is dynamically broken by non-trivial infrared dynamics of some gauge interaction, whose gauge coupling (tilde g) and size N satisfy (tilde g) 2 N ∼> 16π 2 . Such theories allow one to calculate electroweak radiative corrections, including the oblique parameters S, T and U, as long as (tilde g) 2 N/16π 2 and N are sufficiently larger than unity. We study how the duality between the 4D and 5D theories manifests itself in the computation of various physical quantities. In particular, we calculate the electroweak oblique parameters in a warped 5D theory where the electroweak symmetry is broken by boundary conditions at the infrared brane. We show that the value of S obtained in the minimal theory exceeds the experimental bound if the theory is in a weakly coupled regime. This requires either an extension of the minimal model or departure from weak coupling. A particularly interesting scenario is obtained if the gauge couplings in the 5D theory take the largest possible values--the value suggested by naive dimensional analysis. We argue that such a theory can provide a potentially consistent picture for dynamical electroweak symmetry breaking: corrections to the electroweak observables are sufficiently small while realistic fermion masses are obtained without conflicting with bounds from flavor violation. The theory contains only the standard model quarks, leptons and gauge bosons below ≅2 TeV, except for a possible light scalar associated with the radius of the extra dimension. At ≅2 TeV increasingly broad string resonances appear. An analysis of top-quark phenomenology and flavor violation is also presented, which is applicable to both the weakly-coupled and strongly

Pressure induced phase transitions in ceramic compounds containing tetragonal zirconia

Energy Technology Data Exchange (ETDEWEB)

Sparks, R.G.; Pfeiffer, G.; Paesler, M.A.

1988-12-01

Stabilized tetragonal zirconia compounds exhibit a transformation toughening process in which stress applied to the material induces a crystallographic phase transition. The phase transition is accompanied by a volume expansion in the stressed region thereby dissipating stress and increasing the fracture strength of the material. The hydrostatic component of the stress required to induce the phase transition can be investigated by the use of a high pressure technique in combination with Micro-Raman spectroscopy. The intensity of Raman lines characteristic for the crystallographic phases can be used to calculate the amount of material that has undergone the transition as a function of pressure. It was found that pressures on the order of 2-5 kBar were sufficient to produce an almost complete transition from the original tetragonal to the less dense monoclinic phase; while a further increase in pressure caused a gradual reversal of the transition back to the original tetragonal structure.

Phase transitions in liquids with directed intermolecular bonding

OpenAIRE

Son, L.; Ryltcev, R.

2005-01-01

Liquids with quasi - chemical bonding between molecules are described in terms of vertex model. It is shown that this bonding results in liquid - liquid phase transition, which occurs between phases with different mean density of intermolecular bonds. The transition may be suggested to be a universal phenomena for those liquids.

Energy transition and phasing out nuclear

International Nuclear Information System (INIS)

Laponche, Bernard

2013-05-01

In the first part of this report, the author outlines and comments the need of an energy transition in the world: overview of world challenges (world energy consumption and its constraints, a necessary energy transition, new actors and new responsibilities), and describes the German example of an energy transition policy. In the second part, he presents and discusses the main reasons for phasing out nuclear: description of a nuclear plant operation (fission and chain reaction, heat production, production of radioactive elements, how to stop a nuclear reactor), safety and risk issues (protection arrangements, risk and consequence of a nuclear accident), issue of radioactive wastes, relationship between civil techniques and proliferation of nuclear weapons. In a third part, the author proposes an overview of the energy issue in France: final energy consumption, electricity production and consumption, primary energy consumption, characteristics of the French energy system (oil dependency, electricity consumption, and high share of nuclear energy in electricity production). In a last part, the author addresses the issue of energy transition in a perspective of phasing out nuclear: presentation of the Negawatt scenario, assessments made by Global Chance, main programmes of energy transition

Heat capacity characterization at phase transition temperature of Agl superionic

International Nuclear Information System (INIS)

Widowati, Arie

2000-01-01

The phase transition of Agl superionic conductor was investigated by calorometric. A single phase transition was found at (153±5) o C which corresponds to the α - β transition. Calorimetric measurement showed an anomalously high heat capacity with a large discontinues change in the Arrhenius plot, was found above the transition temperature of β - α phase. The maximum heat capacity was found to be ±19.7 cal/gmol. Key words : superionic conductor, thermal capacity

Generalized transport model for phase transition with memory

International Nuclear Information System (INIS)

Chen, Chi; Ciucci, Francesco

2013-01-01

A general model for phenomenological transport in phase transition is derived, which extends Jäckle and Frisch model of phase transition with memory and the Cahn–Hilliard model. In addition to including interfacial energy to account for the presence of interfaces, we introduce viscosity and relaxation contributions, which result from incorporating memory effect into the driving potential. Our simulation results show that even without interfacial energy term, the viscous term can lead to transient diffuse interfaces. From the phase transition induced hysteresis, we discover different energy dissipation mechanism for the interfacial energy and the viscosity effect. In addition, by combining viscosity and interfacial energy, we find that if the former dominates, then the concentration difference across the phase boundary is reduced; conversely, if the interfacial energy is greater then this difference is enlarged.

Thermodynamic phase transition of a black hole in rainbow gravity

Directory of Open Access Journals (Sweden)

Zhong-Wen Feng

2017-09-01

Full Text Available In this letter, using the rainbow functions that were proposed by Magueijo and Smolin, we investigate the thermodynamics and the phase transition of rainbow Schwarzschild black hole. First, we calculate the rainbow gravity corrected Hawking temperature. From this modification, we then derive the local temperature, free energy, and other thermodynamic quantities in an isothermal cavity. Finally, we analyze the critical behavior, thermodynamic stability, and phase transition of the rainbow Schwarzschild black hole. The results show that the rainbow gravity can stop the Hawking radiation in the final stages of black holes' evolution and lead to the remnants of black holes. Furthermore, one can observe that the rainbow Schwarzschild black hole has one first-order phase transition, two second-order phase transitions, and three Hawking–Page-type phase transitions in the framework of rainbow gravity theory.

Group theoretical arguments on the Landau theory of second-order phase transitions applied to the phase transitions in some liquid crystals

International Nuclear Information System (INIS)

Rosciszewski, K.

1979-01-01

The phase transitions between liquids and several of the simplest liquid crystalline phases (nematic, cholesteric, and the simplest types of smectic A and smectic C) were studied from the point of view of the group-theoretical arguments of Landau theory. It was shown that the only possible candidates for second-order phase transitions are those between nematic and smectic A, between centrosymmetric nematic and smectic C and between centrosymmetric smectic A and smectic C. Simple types of density functions for liquid crystalline phases are proposed. (author)

Fermion condensation quantum phase transition versus conventional quantum phase transitions

International Nuclear Information System (INIS)

Shaginyan, V.R.; Han, J.G.; Lee, J.

2004-01-01

The main features of fermion condensation quantum phase transition (FCQPT), which are distinctive in several aspects from that of conventional quantum phase transition (CQPT), are considered. We show that in contrast to CQPT, whose physics in quantum critical region is dominated by thermal and quantum fluctuations and characterized by the absence of quasiparticles, the physics of a Fermi system near FCQPT or undergone FCQPT is controlled by the system of quasiparticles resembling the Landau quasiparticles. Contrary to the Landau quasiparticles, the effective mass of these quasiparticles strongly depends on the temperature, magnetic fields, density, etc. This system of quasiparticles having general properties determines the universal behavior of the Fermi system in question. As a result, the universal behavior persists up to relatively high temperatures comparatively to the case when such a behavior is determined by CQPT. We analyze striking recent measurements of specific heat, charge and heat transport used to study the nature of magnetic field-induced QCP in heavy-fermion metal CeCoIn 5 and show that the observed facts are in good agreement with our scenario based on FCQPT and certainly seem to rule out the critical fluctuations related with CQPT. Our general consideration suggests that FCQPT and the emergence of novel quasiparticles near and behind FCQPT and resembling the Landau quasiparticles are distinctive features intrinsic to strongly correlated substances

Dynamical Symmetries and Causality in Non-Equilibrium Phase Transitions

Directory of Open Access Journals (Sweden)

Malte Henkel

2015-11-01

Full Text Available Dynamical symmetries are of considerable importance in elucidating the complex behaviour of strongly interacting systems with many degrees of freedom. Paradigmatic examples are cooperative phenomena as they arise in phase transitions, where conformal invariance has led to enormous progress in equilibrium phase transitions, especially in two dimensions. Non-equilibrium phase transitions can arise in much larger portions of the parameter space than equilibrium phase transitions. The state of the art of recent attempts to generalise conformal invariance to a new generic symmetry, taking into account the different scaling behaviour of space and time, will be reviewed. Particular attention will be given to the causality properties as they follow for co-variant n-point functions. These are important for the physical identification of n-point functions as responses or correlators.

Universal phase transition in community detectability under a stochastic block model.

Science.gov (United States)

Chen, Pin-Yu; Hero, Alfred O

2015-03-01

We prove the existence of an asymptotic phase-transition threshold on community detectability for the spectral modularity method [M. E. J. Newman, Phys. Rev. E 74, 036104 (2006) and Proc. Natl. Acad. Sci. (USA) 103, 8577 (2006)] under a stochastic block model. The phase transition on community detectability occurs as the intercommunity edge connection probability p grows. This phase transition separates a subcritical regime of small p, where modularity-based community detection successfully identifies the communities, from a supercritical regime of large p where successful community detection is impossible. We show that, as the community sizes become large, the asymptotic phase-transition threshold p* is equal to √[p1p2], where pi(i=1,2) is the within-community edge connection probability. Thus the phase-transition threshold is universal in the sense that it does not depend on the ratio of community sizes. The universal phase-transition phenomenon is validated by simulations for moderately sized communities. Using the derived expression for the phase-transition threshold, we propose an empirical method for estimating this threshold from real-world data.

Multipartite entanglement characterization of a quantum phase transition

Science.gov (United States)

Costantini, G.; Facchi, P.; Florio, G.; Pascazio, S.

2007-07-01

A probability density characterization of multipartite entanglement is tested on the one-dimensional quantum Ising model in a transverse field. The average and second moment of the probability distribution are numerically shown to be good indicators of the quantum phase transition. We comment on multipartite entanglement generation at a quantum phase transition.

Multipartite entanglement characterization of a quantum phase transition

Energy Technology Data Exchange (ETDEWEB)

Costantini, G [Dipartimento di Fisica, Universita di Bari, I-70126 Bari (Italy); Facchi, P [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari (Italy); Florio, G [Dipartimento di Fisica, Universita di Bari, I-70126 Bari (Italy); Pascazio, S [Dipartimento di Fisica, Universita di Bari, I-70126 Bari (Italy)

2007-07-13

A probability density characterization of multipartite entanglement is tested on the one-dimensional quantum Ising model in a transverse field. The average and second moment of the probability distribution are numerically shown to be good indicators of the quantum phase transition. We comment on multipartite entanglement generation at a quantum phase transition.

Phase transitions and glass transition in a hyperquenched silica–alumina glass

DEFF Research Database (Denmark)

Zhang, Y.F.; Zhao, D.H.; Yue, Yuanzheng

2017-01-01

We investigate phase transitions, glass transition, and dynamic behavior in the hyperquenched 69SiO2–31Al2O3 (mol%) glass (SA glass). Upon reheating, the SA glass exhibits a series of thermal responses. Subsequent to the sub-Tg enthalpy release, the glass undergoes a large jump in isobaric heat...... capacity (ΔCp) during glass transition, implying the fragile nature of the SA glass. The mullite starts to form before the end of glass transition, indicating that the SA glass is extremely unstable against crystallization. After the mullite formation, the remaining glass phase exhibits an increased Tg...... and a suppressed ΔCp. The formation of cristobalite at 1553 K indicates the dominance of silica in the remaining glass matrix. The cristobalite gradually re-melts as the isothermal heat-treatment temperature is raised from 1823 to 1853 K, which is well below the melting point of cristobalite, while the amount...

O(5) x U(1) electroweak theory

International Nuclear Information System (INIS)

Mukku, C.; Sayed, W.A.

1981-01-01

An anomaly-free O(5) x U(1) theory of electroweak interactions is described which provides a unified description of electroweak phenomena for two families of standard leptons and quarks. No ''new'' nonsequential-type fermions are introduced, unlike the case for all past studies based on this group. The present scheme requires the introduction of two further charged and three more neutral gauge fields over and above those of SU(2) x U(1) giving rise to new neutral and charged currents

Calorimetric Study of Phase Transitions Involving Twist-Grain-Boundary TGB{A} and TGB{C} Phases

Science.gov (United States)

Navailles, L.; Garland, C. W.; Nguyen, H. T.

1996-09-01

High-resolution calorimetry has been used to determine the heat capacity and latent heat associated with phase transitions in the homologous series of chiral liquid crystals nF_2BTFO_1M_7 [ 3-fluoro-4(1-methylheptyloxy)4'-(4''-alkoxy-2'', 3''-difluorobenzoyloxy)tolane] . These compounds exhibit smectic-C^* (SmC^*), twist-grain-boundary (TGBA for n=10, TGBC for n=11, 12) and cholesteric (N^*) phases. All the phase transitions are first order with small to moderate latent heats. There is a large rounded excess heat capacity peak in the N^* phase that is consistent with the predicted appearance of short-range TGB order (chiral line liquid character). This is analogous to the development of an Abrikosov flux vortex liquid in type-II superconductors. Both the n=11 and 12 homologs exhibit two closely spaced transitions in the region where a single TGBC - N^* transition was expected. This suggests the existence of two thermodynamically distinct TGBC phases. Des exprériences de calorimétrie haute résolution ont été réalisées pour déterminer les chaleurs spécifiques et les chaleurs latentes associées aux transitions de phase des homologues de la série crystal liquide nF_2BTFO_1M_7: 3-fluoro-4[1-methyl-heptyloxy]4'-(4''-alcoxy-2'', 3''-difluorobenzoyloxy)tolanes. Ces produits présentent la phase smectique C^* (SmC^*), les phases à torsion par joint de grain (TGBA pour n=10 et TGBC pour n=11, 12) et la phase cholestérique (N^*). Toutes les transitions de phase sont du premier ordre. La chaleur latente associée à ces transitions est faibles ou modérée. Nous observons, dans la phase N^*, un grand pic arrondi qui est en accord avec les prédictions de l'apparition d'un ordre TGB à courte distance (liquide de ligne de dislocation). Ce phénomène est l'analogue du liquide de vortex dans les supraconducteurs de type II. Les composés n=11 et 12 présentent, dans la région où nous attendions une transition TGBC - N^* unique, deux transitions sur un très faible

The problem of phase transitions in statistical mechanics

International Nuclear Information System (INIS)

Martynov, Georgii A

1999-01-01

The first part of this review deals with the single-phase approach to the statistical theory of phase transitions. This approach is based on the assumption that a first-order phase transition is due to the loss of stability of the parent phase. We demonstrate that it is practically impossible to find the coordinates of the transition points using this criterion in the framework of the global Gibbs theory which describes the state of the entire macroscopic system. On the basis of the Ornstein-Zernike equation we formulate a local approach that analyzes the state of matter inside the correlation sphere of radius R c ∼ 10 A. This approach is proved to be as rigorous as the Gibbs theory. In the context of the local approach we formulate a criterion that allows finding the transition points without calculating the chemical potential and the pressure of the second conjugate phase. In the second part of the review we consider second-order phase transitions (critical phenomena). The Kadanoff-Wilson theory of critical phenomena is analyzed, based on the global Gibbs approach. Again we use the Ornstein-Zernike equation to formulate a local theory of critical phenomena. With regard to experimentally established quantities this theory yields precisely the same results as the Kadanoff-Wilson theory; secondly, the local approach allows the prediction of many previously unknown details of critical phenomena, and thirdly, the local approach paves the way for constructing a unified theory of liquids that will describe the behavior of matter not only in the regular domain of the phase diagram, but also at the critical point and in its vicinity. (reviews of topical problems)

Concepts of electroweak symmetry breaking and Higgs physics

International Nuclear Information System (INIS)

Gomez-Bock, M.; Zerwas, P.M.; RWTH Aachen; Univ. Paris- Sud, Orsay

2007-12-01

We present an introduction to the basic concepts of electroweak symmetry breaking and Higgs physics within the Standard Model and its supersymmetric extensions. A brief overview will also be given on alternative mechanisms of electroweak symmetry breaking. In addition to the theoretical basis, the present experimental status of Higgs physics and prospects at the Tevatron, the LHC and e + e - linear colliders are discussed. (orig.)

Concepts of electroweak symmetry breaking and Higgs physics

Energy Technology Data Exchange (ETDEWEB)

Gomez-Bock, M. [Benemerita Univ., Puebla (Mexico). Inst. de Fisica; Mondragon, M. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Fisica; Muehlleitner, M. [Laboratoire d' Annecy-Le-Vieux de Physique Theorique, 74 (France)]|[CERN - European Organization for Nuclear Research, Geneva (Switzerland). Theory Div.; Spira, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Zerwas, P.M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[RWTH Aachen (Germany). Inst. Theor. Physik E]|[Univ. Paris- Sud, Orsay (France). Laboratoire de Physique Theorique

2007-12-15

We present an introduction to the basic concepts of electroweak symmetry breaking and Higgs physics within the Standard Model and its supersymmetric extensions. A brief overview will also be given on alternative mechanisms of electroweak symmetry breaking. In addition to the theoretical basis, the present experimental status of Higgs physics and prospects at the Tevatron, the LHC and e{sup +}e{sup -} linear colliders are discussed. (orig.)

O(5) x U(1) electroweak theory

International Nuclear Information System (INIS)

Mukku, C.; Sayed, W.A.

1980-12-01

An anomaly free O(5) x U(1) theory of electroweak interactions is described which provides a unified description of electroweak phenomena for two families of standard leptons and quarks. No ''new'' non-sequential type fermions of the standard model are introduced as has been the case for all past studies based on this group. The present scheme requires the introduction of two further charged and three more neutral gauge fields over and above the Wsup(+-), Z and photon fields of SU(2) x U(1) giving rise to new neutral and charged currents. In this note we outline our reasons for proposing the present electroweak scheme, give the basic structure of the model, discuss the symmetry breaking pattern which ensures that SU(2)sub(L) x U(1) is the low energy symmetry, point out the new interactions present in the extended framework and obtain limits on the masses of all the gauge fields. (author)

Martensitic phase transitions in Co-0.85 at % Fe

International Nuclear Information System (INIS)

Prem, M.

1997-12-01

Co-0.85at%Fe shows the two martensitic phase transitions hcp-dhcp and dhcp-fcc. The lattice dynamics of Co-0.85at%Fe was investigated by the means of inelastic neutron scattering at a series of temperatures up to 750K in order to understand the two martensitic phase transitions of this system. In all of the measured phonon branches anomalies were neither found near the hcp-dhcp phase transition nor going through the dhcp-fcc transition. Lattice-parameter scans were performed through the whole temperature range. Diffuse neutron scattering revealed a lattice parameter shift between the dhcp and fcc phase of ∼0.4 % measured at the same temperature. This was possible because the system shows a wide temperature hysteresis at the two phase transitions. In the temperature region of coexistence of dhcp and fcc phase diffuse satellites arose near the (111)fcc Bragg peak (which is equivalent to the (00.2)dhcp peak). Their intensity varied in accordance to the volume fraction of the phases but vanished on changing wavelength. The elastic measurements were performed at the Austrian triple axis spectrometer VALSE located at the Laboratoire Leon Brillouin (LLB) in Saclay (F); the inelastic measurements were performed at the spectrometers IN3 and INS of the Institute Laue Langevin (ILL) in Grenoble (F). (author)

Phase transition in finite systems

Energy Technology Data Exchange (ETDEWEB)

Chomaz, Ph.; Duflot, V. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France); Duflot, V.; Gulminelli, F. [Laboratoire de Physique Corpusculaire, LPC-ISMRa, CNRS-IN2P3, 14 - Caen (France)

2000-07-01

The general problem of the definition of a phase transition without employing the thermodynamical limit is addressed. Different necessary conditions are considered and illustrated with examples from different nuclear and general physics phenomenologies. (authors)

Phase transition in finite systems

International Nuclear Information System (INIS)

Chomaz, Ph.; Duflot, V.; Duflot, V.; Gulminelli, F.

2000-01-01

The general problem of the definition of a phase transition without employing the thermodynamical limit is addressed. Different necessary conditions are considered and illustrated with examples from different nuclear and general physics phenomenologies. (authors)

Electroweak interactions at LEP

International Nuclear Information System (INIS)

Borgia, B.

1991-01-01

Electroweak interaction at LEP are a subject based on a wealth of data, given the success of the CERN e + e - storage ring. The author will report on the results from the four experiments, ALEPH, DELPHI, L3 and OPAL after the analysis of about 1/2 of the data collected in 1989 and 1990. The review will cover the electroweak aspects of the process e + e - → Z* → f bar f where the fermions can be either quarks or leptons. The analysis of experimental data is based on the determination of the cross section integrated on the solid angle and on the asymmetry of forward-backward leptons in the final state. In this game the knowledge of the center mass energy is fundamental as the determination of the luminosity by which the event rate is normalized to compute the absolute cross section. Therefore a specific attention is given to these subjects

Electroweak probes with ATLAS

CERN Document Server

Milov, Alexander; The ATLAS collaboration

2018-01-01

Measuring electroweak bosons in relativistic heavy ion collisions at high energy provide an opportunity to understand temporal evolution of the quark-gluon plasma created in such collisions by constraining the initial state of the interaction. Due to lack of colour charges the bosons and or particles produced in their leptonic decays are unaffected by the quark-gluon plasma and therefore preserve the information about the very early stage of the collision when they were born. This singles EW bosons as a unique and very interesting class of observables in HI collisions. The ATLAS experiment at LHC measures production of electroweak bosons in $pp$, $p$+Pb and Pb+Pb collisions systems. A review of the existing results is given in this proceeding that includes studies made with isolated photons to constraint kinematic properties and flavour composition of associated jets, measurements of $W$ and $Z$ bosons used to estimate nuclear modification of PDF and the production rates of the bosons used to verify geometric...

Strong Electroweak Symmetry Breaking

CERN Document Server

Grinstein, Benjamin

2011-01-01

Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...

Signatures of topological phase transitions in mesoscopic superconducting rings

International Nuclear Information System (INIS)

Pientka, Falko; Romito, Alessandro; Duckheim, Mathias; Oppen, Felix von; Oreg, Yuval

2013-01-01

We investigate Josephson currents in mesoscopic rings with a weak link which are in or near a topological superconducting phase. As a paradigmatic example, we consider the Kitaev model of a spinless p-wave superconductor in one dimension, emphasizing how this model emerges from more realistic settings based on semiconductor nanowires. We show that the flux periodicity of the Josephson current provides signatures of the topological phase transition and the emergence of Majorana fermions (MF) situated on both sides of the weak link even when fermion parity is not a good quantum number. In large rings, the MF hybridize only across the weak link. In this case, the Josephson current is h/e periodic in the flux threading the loop when fermion parity is a good quantum number but reverts to the more conventional h/2e periodicity in the presence of fermion-parity changing relaxation processes. In mesoscopic rings, the MF also hybridize through their overlap in the interior of the superconducting ring. We find that in the topological superconducting phase, this gives rise to an h/e-periodic contribution even when fermion parity is not conserved and that this contribution exhibits a peak near the topological phase transition. This signature of the topological phase transition is robust to the effects of disorder. As a byproduct, we find that close to the topological phase transition, disorder drives the system deeper into the topological phase. This is in stark contrast to the known behavior far from the phase transition, where disorder tends to suppress the topological phase. (paper)

Shear induced phase transitions induced in edible fats

Science.gov (United States)

Mazzanti, Gianfranco; Welch, Sarah E.; Marangoni, Alejandro G.; Sirota, Eric B.; Idziak, Stefan H. J.

2003-03-01

The food industry crystallizes fats under different conditions of temperature and shear to obtain products with desired crystalline phases. Milk fat, palm oil, cocoa butter and chocolate were crystallized from the melt in a temperature controlled Couette cell. Synchrotron x-ray diffraction studies were conducted to examine the role of shear on the phase transitions seen in edible fats. The shear forces on the crystals induced acceleration of the alpha to beta-prime phase transition with increasing shear rate in milk fat and palm oil. The increase was slow at low shear rates and became very strong above 360 s-1. In cocoa butter the acceleration between beta-prime-III and beta-V phase transition increased until a maximum of at 360 s-1, and then decreased, showing competition between enhanced heat transfer and viscous heat generation.

Structural phase transition in monolayer MoTe2 driven by electrostatic doping

Science.gov (United States)

Wang, Ying; Xiao, Jun; Zhu, Hanyu; Li, Yao; Alsaid, Yousif; Fong, King Yan; Zhou, Yao; Wang, Siqi; Shi, Wu; Wang, Yuan; Zettl, Alex; Reed, Evan J.; Zhang, Xiang

2017-10-01

Monolayers of transition-metal dichalcogenides (TMDs) exhibit numerous crystal phases with distinct structures, symmetries and physical properties. Exploring the physics of transitions between these different structural phases in two dimensions may provide a means of switching material properties, with implications for potential applications. Structural phase transitions in TMDs have so far been induced by thermal or chemical means; purely electrostatic control over crystal phases through electrostatic doping was recently proposed as a theoretical possibility, but has not yet been realized. Here we report the experimental demonstration of an electrostatic-doping-driven phase transition between the hexagonal and monoclinic phases of monolayer molybdenum ditelluride (MoTe2). We find that the phase transition shows a hysteretic loop in Raman spectra, and can be reversed by increasing or decreasing the gate voltage. We also combine second-harmonic generation spectroscopy with polarization-resolved Raman spectroscopy to show that the induced monoclinic phase preserves the crystal orientation of the original hexagonal phase. Moreover, this structural phase transition occurs simultaneously across the whole sample. This electrostatic-doping control of structural phase transition opens up new possibilities for developing phase-change devices based on atomically thin membranes.

Model for pairing phase transition in atomic nuclei

International Nuclear Information System (INIS)

Schiller, A.; Guttormsen, M.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.

2002-01-01

A model is developed which allows the investigation and classification of the pairing phase transition in atomic nuclei. The regions of the parameter space are discussed for which a pairing phase transition can be observed. The model parameters include number of particles, attenuation of pairing correlations with increasing seniority, single-particle level spacing, and pairing gap parameter

Searches for Electroweak Signatures of Supersymmetry at ATLAS and CMS

CERN Document Server

Khoo, Teng Jian; The ATLAS collaboration

2018-01-01

Searches for strongly-produced superparticles at the Large Hadron Collider have excluded gluinos and squarks of all generations up to the TeV scale. While limited by statistics, electroweak signatures remain less thoroughly explored, and in particular the Higgsino sector has proven challenging. Conventional searches for leptons associated with missing transverse momentum do not fully cover the phase space, requiring new approaches to extend experimental sensitivity. Dedicated reconstruction techniques address the challenge posed by mass-degenerate spectra. By looking beyond the assumption of leptonic signatures, searches for gauge-mediated supersymmetry have broken new ground.

Deconfinement phase transition in QCD with heavy quarks

International Nuclear Information System (INIS)

Attig, N.; Petersson, B.; Wolff, M.; Gavai, R.V.

1988-01-01

Using the pseudo-fermion method to simulate QCD with dynamical quarks we investigate the effects of heavy dynamical quarks of 2 flavours on the deconfinement phase transition in the quenched QCD. As the mass of the quark is decreased the phase transition weakens as expected. Compared to the earlier results with leading order hopping parameter expansion, however, the weakening is less rapid. Our estimated upper bound on the critical mass where the transition becomes continuous is 1.5-2 times lower than earlier results. (orig.)

Phase transition in a modified square Josephson-junction array

CERN Document Server

Han, J

1999-01-01

We study the phase transition in a modified square proximity-coupled Josephson-junction array with small superconducting islands at the center of each plaquette. We find that the modified square array undergoes a Kosterlitz-Thouless-Berezinskii-like phase transition, but at a lower temperature than the simple square array with the same single-junction critical current. The IV characteristics, as well as the phase transition, resemble qualitatively those of a disordered simple square array. The effects of the presence of the center islands in the modified square array are discussed.

Theory Overview of Electroweak Physics at Hadron Colliders

Energy Technology Data Exchange (ETDEWEB)

Campbell, John M. [Fermilab

2016-09-03

This contribution summarizes some of the important theoretical progress that has been made in the arena of electroweak physics at hadron colliders. The focus is on developments that have sharpened theoretical predictions for final states produced through electroweak processes. Special attention is paid to new results that have been presented in the last year, since LHCP2015, as well as on key issues for future measurements at the LHC.

Gravitationally self-induced phase transition

International Nuclear Information System (INIS)

Novello, M.; Duque, S.L.S.

1990-01-01

We propose a new mechanism by means of which a phase transition can be stimulated by self-gravitating matter. We suggest that this model could be used to explain the observed isotropy of the Universe. (orig.)

Quantum phase transitions between a class of symmetry protected topological states

Energy Technology Data Exchange (ETDEWEB)

Tsui, Lokman; Jiang, Hong-Chen; Lu, Yuan-Ming; Lee, Dung-Hai

2015-07-01

The subject of this paper is the phase transition between symmetry protected topological states (SPTs). We consider spatial dimension d and symmetry group G so that the cohomology group, Hd+1(G,U(1)), contains at least one Z2n or Z factor. We show that the phase transition between the trivial SPT and the root states that generate the Z2n or Z groups can be induced on the boundary of a (d+1)-dimensional View the MathML source-symmetric SPT by a View the MathML source symmetry breaking field. Moreover we show these boundary phase transitions can be “transplanted” to d dimensions and realized in lattice models as a function of a tuning parameter. The price one pays is for the critical value of the tuning parameter there is an extra non-local (duality-like) symmetry. In the case where the phase transition is continuous, our theory predicts the presence of unusual (sometimes fractionalized) excitations corresponding to delocalized boundary excitations of the non-trivial SPT on one side of the transition. This theory also predicts other phase transition scenarios including first order transition and transition via an intermediate symmetry breaking phase.

Superconducting phase transition in STM tips

Energy Technology Data Exchange (ETDEWEB)

Eltschka, Matthias; Jaeck, Berthold; Assig, Maximilian; Etzkorn, Markus; Ast, Christian R. [Max Planck Institute for Solid State Research, Stuttgart (Germany); Kern, Klaus [Max Planck Institute for Solid State Research, Stuttgart (Germany); Ecole Polytechnique Federale de Lausanne (Switzerland)

2015-07-01

The superconducting properties of systems with dimensions comparable to the London penetration depth considerably differ from macroscopic systems. We have studied the superconducting phase transition of vanadium STM tips in external magnetic fields. Employing Maki's theory we extract the superconducting parameters such as the gap or the Zeeman splitting from differential conductance spectra. While the Zeeman splitting follows the theoretical description of a system with s=1/2 and g=2, the superconducting gaps as well as the critical fields depend on the specific tip. For a better understanding of the experimental results, we solve a one dimensional Usadel equation modeling the superconducting tip as a cone with the opening angle α in an external magnetic field. We find that only a small region at the apex of the tip is superconducting in high magnetic fields and that the order of the phase transition is directly determined by α. Further, the spectral broadening increases with α indicating an intrinsic broadening mechanism due to the conical shape of the tip. Comparing these calculations to our experimental results reveals the order of the superconducting phase transition of the STM tips.

CosmoTransitions: Computing cosmological phase transition temperatures and bubble profiles with multiple fields

Science.gov (United States)

Wainwright, Carroll L.

2012-09-01

I present a numerical package (CosmoTransitions) for analyzing finite-temperature cosmological phase transitions driven by single or multiple scalar fields. The package analyzes the different vacua of a theory to determine their critical temperatures (where the vacuum energy levels are degenerate), their supercooling temperatures, and the bubble wall profiles which separate the phases and describe their tunneling dynamics. I introduce a new method of path deformation to find the profiles of both thin- and thick-walled bubbles. CosmoTransitions is freely available for public use.Program summaryProgram Title: CosmoTransitionsCatalogue identifier: AEML_v1_0Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEML_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 8775No. of bytes in distributed program, including test data, etc.: 621096Distribution format: tar.gzProgramming language: Python.Computer: Developed on a 2009 MacBook Pro. No computer-specific optimization was performed.Operating system: Designed and tested on Mac OS X 10.6.8. Compatible with any OS with Python installed.RAM: Approximately 50 MB, mostly for loading plotting packages.Classification: 1.9, 11.1.External routines: SciPy, NumPy, matplotLibNature of problem: I describe a program to analyze early-Universe finite-temperature phase transitions with multiple scalar fields. The goal is to analyze the phase structure of an input theory, determine the amount of supercooling at each phase transition, and find the bubble-wall profiles of the nucleated bubbles that drive the transitions.Solution method: To find the bubble-wall profile, the program assumes that tunneling happens along a fixed path in field space. This reduces the equations of motion to one dimension, which can then be solved using the overshoot

Explosive transitions to synchronization in networks of phase oscillators.

Science.gov (United States)

Leyva, I; Navas, A; Sendiña-Nadal, I; Almendral, J A; Buldú, J M; Zanin, M; Papo, D; Boccaletti, S

2013-01-01

The emergence of dynamical abrupt transitions in the macroscopic state of a system is currently a subject of the utmost interest. The occurrence of a first-order phase transition to synchronization of an ensemble of networked phase oscillators was reported, so far, for very particular network architectures. Here, we show how a sharp, discontinuous transition can occur, instead, as a generic feature of networks of phase oscillators. Precisely, we set conditions for the transition from unsynchronized to synchronized states to be first-order, and demonstrate how these conditions can be attained in a very wide spectrum of situations. We then show how the occurrence of such transitions is always accompanied by the spontaneous setting of frequency-degree correlation features. Third, we show that the conditions for abrupt transitions can be even softened in several cases. Finally, we discuss, as a possible application, the use of this phenomenon to express magnetic-like states of synchronization.

High-pressure phase transition and phase diagram of gallium arsenide

Science.gov (United States)

Besson, J. M.; Itié, J. P.; Polian, A.; Weill, G.; Mansot, J. L.; Gonzalez, J.

1991-09-01

Under hydrostatic pressure, cubic GaAs-I undergoes phase transitions to at least two orthorhombic structures. The initial phase transition to GaAs-II has been investigated by optical-transmittance measurements, Raman scattering, and x-ray absorption. The structure of pressurized samples, which are retrieved at ambient, has been studied by x-ray diffraction and high-resolution diffraction microscopy. Various criteria that define the domain of stability of GaAs-I are examined, such as the occurrence of crystalline defects, the local variation in atomic coordination number, or the actual change in crystal structure. These are shown not to occur at the same pressure at 300 K, the latter being observable only several GPa above the actual thermodynamic instability pressure of GaAs-I. Comparison of the evolution of these parameters on increasing and decreasing pressure locates the thermodynamic transition region GaAs-I-->GaAs-II at 12+/-1.5 GPa and at 300 K that is lower than generally reported. The use of thermodynamic relations around the triple point, and of regularities in the properties of isoelectronic and isostructural III-V compounds, yields a phase diagram for GaAs which is consistent with this value.

Van der Waals phase transition in the framework of holography

International Nuclear Information System (INIS)

Zeng, Xiao-Xiong; Li, Li-Fang

2017-01-01

Phase structure of the quintessence Reissner–Nordström–AdS black hole is probed by the nonlocal observables such as holographic entanglement entropy and two point correlation function. Our result shows that, as the case of the thermal entropy, both the observables exhibit the Van der Waals-like phase transition. To reinforce this conclusion, we further check the equal area law for the first order phase transition and critical exponent of the heat capacity for the second order phase transition. We also discuss the effect of the state parameter on the phase structure of the nonlocal observables.

Van der Waals phase transition in the framework of holography

Energy Technology Data Exchange (ETDEWEB)

Zeng, Xiao-Xiong, E-mail: xxzeng@itp.ac.cn [State School of Material Science and Engineering, Chongqing Jiaotong University, Chongqing 400074 (China); Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); Li, Li-Fang, E-mail: lilf@itp.ac.cn [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China)

2017-01-10

Phase structure of the quintessence Reissner–Nordström–AdS black hole is probed by the nonlocal observables such as holographic entanglement entropy and two point correlation function. Our result shows that, as the case of the thermal entropy, both the observables exhibit the Van der Waals-like phase transition. To reinforce this conclusion, we further check the equal area law for the first order phase transition and critical exponent of the heat capacity for the second order phase transition. We also discuss the effect of the state parameter on the phase structure of the nonlocal observables.

Van der Waals phase transition in the framework of holography

Directory of Open Access Journals (Sweden)

Xiao-Xiong Zeng

2017-01-01

Full Text Available Phase structure of the quintessence Reissner–Nordström–AdS black hole is probed by the nonlocal observables such as holographic entanglement entropy and two point correlation function. Our result shows that, as the case of the thermal entropy, both the observables exhibit the Van der Waals-like phase transition. To reinforce this conclusion, we further check the equal area law for the first order phase transition and critical exponent of the heat capacity for the second order phase transition. We also discuss the effect of the state parameter on the phase structure of the nonlocal observables.

Moessbauer study of phase transitions under high hydrostatic pressures. 1

International Nuclear Information System (INIS)

Kapitanov, E.V.; Yakovlev, E.N.

1979-01-01

Experimental results of the hydrostatic pressure influence on Moessbauer spectrum parameters are obtained over the pressure range including the area of structural phase transition. A linear increase of the Moessbauer effect probability (recoilless fraction) is accompanied by a linear decrease of the electron density at tin nuclei within the pressure range foregoing the phase transition. The electric resistance and the recoilless fraction of the new phase of Mg 2 Sn are lower, but the electron density at tin nuclei is greater than the initial phase ones. Hydrostatic conditions allow to fix clearly the diphasic transition area and to determine the influence of the pressure on the Moessbauer line position and on the recoilless fraction of the high pressure phase. The phase transition heat Q = 415 cal mol -1 is calculated using recoilless fractions of the high and low pressure phases at 25 kbar. The present results are qualitatively and quantitatively different from the results, obtained at nonhydrostatic conditions. (author)

Continuous Easy-Plane Deconfined Phase Transition on the Kagome Lattice

Science.gov (United States)

Zhang, Xue-Feng; He, Yin-Chen; Eggert, Sebastian; Moessner, Roderich; Pollmann, Frank

2018-03-01

We use large scale quantum Monte Carlo simulations to study an extended Hubbard model of hard core bosons on the kagome lattice. In the limit of strong nearest-neighbor interactions at 1 /3 filling, the interplay between frustration and quantum fluctuations leads to a valence bond solid ground state. The system undergoes a quantum phase transition to a superfluid phase as the interaction strength is decreased. It is still under debate whether the transition is weakly first order or represents an unconventional continuous phase transition. We present a theory in terms of an easy plane noncompact C P1 gauge theory describing the phase transition at 1 /3 filling. Utilizing large scale quantum Monte Carlo simulations with parallel tempering in the canonical ensemble up to 15552 spins, we provide evidence that the phase transition is continuous at exactly 1 /3 filling. A careful finite size scaling analysis reveals an unconventional scaling behavior hinting at deconfined quantum criticality.

Precision electroweak heavy flavor results from LEP and SLC

International Nuclear Information System (INIS)

Brown, D.

1993-11-01

The traditional Electroweak measurements made at Z factories using undifferentiated hadronic and leptonic Z decays will soon be reaching their asymptotic limits in precision. Consequently, much attention has recently been focused on extracting electroweak parameters from hadronic decays differentiated through heavy flavor tagging. This paper gives an overview of the various techniques used at LEP and SLC to tag heavy flavors. The measurements of the forward backward asymmetries and the partial widths for Z→b anti b and Z→c anti c decays are briefly described. The most recent results for these are presented, and are interpreted within the framework of the Standard Model. The precision of the electroweak parameters extracted from these measurements is shown to be comparable to that from other techniques. Assembling all the LEP electroweak data, constraints on the top and Higgs masses are found. The heavy flavor results, and in particular the new, very accurate Z→b anti b partial width measurements, are shown to play a key role in these limits. (orig.)

Photoinduced charge transfer phase transition in cesium manganese hexacyanoferrate

International Nuclear Information System (INIS)

Matsuda, Tomoyuki; Tokoro, Hiroko; Hashimoto, Kazuhito; Ohkoshi, Shin-ichi

2007-01-01

Cesium manganese hexacyanoferrate, Cs 1.51 Mn[Fe(CN) 6 ], shows a thermal phase transition between Mn II -NC-Fe III [high-temperature (HT) phase] and Mn III -NC-Fe II [low-temperature (LT) phase] with phase transition temperatures of 170 K (HT→LT) and 230 K (LT→HT). The LT phase shows ferromagnetism with Curie temperature of 7 K and coercive field of 60 Oe. Irradiating with 532 nm laser light converts the LT phase into the photoinduced (PI) phase, which does not have spontaneous magnetization. The electronic state of the PI phase corresponds to that of the HT phase and the relaxation temperature from the PI to the LT phase is observed at 90 K

The Physics of Structural Phase Transitions

CERN Document Server

Fujimoto, Minoru

2005-01-01

Phase transitions in which crystalline solids undergo structural changes present an interesting problem in the interplay between the crystal structure and the ordering process that is typically nonlinear. Intended for readers with prior knowledge of basic condensed-matter physics, this book emphasizes the physics behind spontaneous structural changes in crystals. Starting with the relevant thermodynamic principles, the text discusses the nature of order variables in collective motion in structural phase transitions, where a singularity in such a collective mode is responsible for lattice instability as revealed by soft phonons. In this book, critical anomalies at second-order structural transitions are first analyzed with the condensate model. Discussions on the nonlinear ordering mechanism are followed with the soliton theory, thereby interpreting the role of long-range order. Relevant details for nonlinear mathematics are therefore given for minimum necessity. The text also discusses experimental methods fo...

Role of relativity in high-pressure phase transitions of thallium.

Science.gov (United States)

Kotmool, Komsilp; Chakraborty, Sudip; Bovornratanaraks, Thiti; Ahuja, Rajeev

2017-02-20

We demonstrate the relativistic effects in high-pressure phase transitions of heavy element thallium. The known first phase transition from h.c.p. to f.c.c. is initially investigated by various relativistic levels and exchange-correlation functionals as implemented in FPLO method, as well as scalar relativistic scheme within PAW formalism. The electronic structure calculations are interpreted from the perspective of energetic stability and electronic density of states. The full relativistic scheme (FR) within L(S)DA performs to be the scheme that resembles mostly with experimental results with a transition pressure of 3 GPa. The s-p hybridization and the valence-core overlapping of 6s and 5d states are the primary reasons behind the f.c.c. phase occurrence. A recent proposed phase, i.e., a body-centered tetragonal (b.c.t.) phase, is confirmed with a small distortion from the f.c.c. phase. We have also predicted a reversible b.c.t. → f.c.c. phase transition at 800 GPa. This finding has been suggested that almost all the III-A elements (Ga, In and Tl) exhibit the b.c.t. → f.c.c. phase transition at extremely high pressure.

Electroweak penguin effects beyond leading logarithms in the B-meson decays B- → K-Φ and B- → π- anti K0

International Nuclear Information System (INIS)

Fleischer, R.

1994-01-01

Using the low energy effective Hamiltonian for vertical stroke ΔBvertical stroke = 1, ΔC=ΔU=0 transitions, which has been calculated recently by Buras et al. beyond the leading logarithmic approximation, we analyze the penguin-induced B-meson decays B - → K - Φ and B - → π - anti K 0 within the framework of the Bauer-Stech-Wirbel model and find, in contradiction to naive expectations, that the decay mode B - → K - Φ is affected strongly by electroweak penguin operators. These contributions depend on the value of the top-quark mass and reduce the branching ratio BR(B - → K - Φ) by factors of 0.8..0.6 for m t =(130..250) GeV, respectively, relative to the results obtained by taking into account only QCD penguin operator contributions. On the other hand, we find that the effects of the electroweak penguins are very small for the transition B - → π - anti K 0 . (orig.)

Neutron and x-ray scattering studies of ferroelectric phase transitions

International Nuclear Information System (INIS)

Dolling, G.

1982-08-01

The subject of ferroelectric type phase transitions is introduced by means of examples of two main classes (a) displacive transitions, e.g. KNbO 3 , and (b) order-disorder transitions, e.g. NaNO 2 . The significance of crystal structure and crystal dynamics (i.e. the phonon dispersion relations) for ferroelectric behaviour is emphasized. The chief methods for structure determination are x-ray and neutron diffraction, while the most powerful of all techniques for studying phonon properties is that of coherent inelastic neutron scattering. The most useful type of neutron spectrometer for phase transition studies, the triple axis crystal spectrometer, is discussed in detail. The history of the soft mode theory of displacive phase transitions, and its application to the antiferroelectric and 'almost ferroelectric' transitions in SrTiO 3 , provides an introduction to more recent developments in this area, including over-damped soft modes, central peaks and critical scattering, incommensurate phase transitions (e.g. K 2 SeO 4 ), amplitudons, phasons and finally solitions. The treatment throughout is descriptive and introductory, designed for graduate students

Possibility of a large electroweak penguin contribution in B→Kπ modes

International Nuclear Information System (INIS)

Yoshikawa, Tadashi

2003-01-01

We discuss the possibility of a large electroweak penguin contribution in B→Kπ from recent experimental data. The several relations among the branching ratios which realize when the contributions from tree type and electroweak penguin contributions are small compared with the gluon penguin can be treated as the expansion parameters do not satisfy the data. The difference comes from the r 2 term which is the square of the ratio with the gluon penguin diagram and the main contribution comes from the electroweak penguin diagram. We find that the electroweak penguin contribution may be too large to explain the experimental data. If the magnitude estimated from experiment is quite large compared with the theoretical estimation, then it may be including some new physics effects

The global electroweak Standard Model fit after the Higgs discovery

CERN Document Server

Baak, Max

2013-01-01

We present an update of the global Standard Model (SM) fit to electroweak precision data under the assumption that the new particle discovered at the LHC is the SM Higgs boson. In this scenario all parameters entering the calculations of electroweak precision observalbes are known, allowing, for the first time, to over-constrain the SM at the electroweak scale and assert its validity. Within the SM the W boson mass and the effective weak mixing angle can be accurately predicted from the global fit. The results are compatible with, and exceed in precision, the direct measurements. An updated determination of the S, T and U parameters, which parametrize the oblique vacuum corrections, is given. The obtained values show good consistency with the SM expectation and no direct signs of new physics are seen. We conclude with an outlook to the global electroweak fit for a future e+e- collider.

Studying the Electroweak Sector with the ATLAS Detector

CERN Document Server

Bittrich, Carsten; The ATLAS collaboration

2018-01-01

The large integrated luminosities that are available at the LHC, allow to test the gauge structure of the electroweak sector of the Standard Model to highest precision. In this talk, we review the latest results of the ATLAS collaboration involving di-boson and multiboson final states as well as the corresponding limits on anomalous gauge couplings. Moreover, we discuss the electroweak production of vector boson at 13 TeV. Another approach to test the consistency of the electroweak sector is via precision measurements. ATLAS has recently published a measurement of the tau-polarization in Z events as well as a three dimensional cross-section measurement of the Drell-Yan process. The latter allows for the extraction of the forward-backward asymmetry that can be interpreted as a measurement of the weak mixing angle. Both results will be presented and discussed.

Studies of Zγ electroweak production in association with a high-mass di-jet system in pp collisions at √s = 8 TeV with the ATLAS detector

CERN Document Server

Liang, Zhijun; The ATLAS collaboration

2017-01-01

Abstract: this poster presents fiducial cross section measurements of electroweak production of two jets in association with a Z boson and a high-energy photon. The measurements use 20.3 fb−1 of proton-proton collision data at a center-of-mass energy of s√ = 8 TeV recorded with the ATLAS detector in 2012. This analysis aims to give evidence for the existence of vector boson scattering (VBS) process WW -> Zγ. The electroweak component of Zγjj is extracted by a fit to the distribution sensitive to the VBS signature in a fiducial region chosen to enhance the electroweak contribution over the dominant background in which the jets are produced via the strong interaction. Two sigma significance is observed for electroweak Zγjj production process. Quartic couplings of vector bosons are studied in regions of phase space with an enhanced contribution from pure electroweak production, sensitive to vector-boson scattering processes WW -> Zγ. No deviations from Standard Model predictions are observed and constrai...

Signatures of a dissipative phase transition in photon correlation measurements

Science.gov (United States)

Fink, Thomas; Schade, Anne; Höfling, Sven; Schneider, Christian; Imamoglu, Ataç

2018-04-01

Understanding and characterizing phase transitions in driven-dissipative systems constitutes a new frontier for many-body physics1-8. A generic feature of dissipative phase transitions is a vanishing gap in the Liouvillian spectrum9, which leads to long-lived deviations from the steady state as the system is driven towards the transition. Here, we show that photon correlation measurements can be used to characterize the corresponding critical slowing down of non-equilibrium dynamics. We focus on the extensively studied phenomenon of optical bistability in GaAs cavity polaritons10,11, which can be described as a first-order dissipative phase transition12-14. Increasing the excitation strength towards the bistable range results in an increasing photon-bunching signal along with a decay time that is prolonged by more than nine orders of magnitude as compared with that of single polaritons. In the limit of strong polariton interactions leading to pronounced quantum fluctuations, the mean-field bistability threshold is washed out. Nevertheless, the functional form with which the Liouvillian gap closes as the thermodynamic limit is approached provides a signature of the emerging dissipative phase transition. Our results establish photon correlation measurements as an invaluable tool for studying dynamical properties of dissipative phase transitions without requiring phase-sensitive interferometric measurements.

Electroweak corrections

International Nuclear Information System (INIS)

Beenakker, W.J.P.

1989-01-01

The prospect of high accuracy measurements investigating the weak interactions, which are expected to take place at the electron-positron storage ring LEP at CERN and the linear collider SCL at SLAC, offers the possibility to study also the weak quantum effects. In order to distinguish if the measured weak quantum effects lie within the margins set by the standard model and those bearing traces of new physics one had to go beyond the lowest order and also include electroweak radiative corrections (EWRC) in theoretical calculations. These higher-order corrections also can offer the possibility of getting information about two particles present in the Glashow-Salam-Weinberg model (GSW), but not discovered up till now, the top quark and the Higgs boson. In ch. 2 the GSW standard model of electroweak interactions is described. In ch. 3 some special techniques are described for determination of integrals which are responsible for numerical instabilities caused by large canceling terms encountered in the calculation of EWRC effects, and methods necessary to get hold of the extensive algebra typical for EWRC. In ch. 4 various aspects related to EWRC effects are discussed, in particular the dependence of the unknown model parameters which are the masses of the top quark and the Higgs boson. The processes which are discussed are production of heavy fermions from electron-positron annihilation and those of the fermionic decay of the Z gauge boson. (H.W.). 106 refs.; 30 figs.; 6 tabs.; schemes

Pressure-induced phase transitions in nanocrystalline ReO3

International Nuclear Information System (INIS)

Biswas, Kanishka; Muthu, D V S; Sood, A K; Kruger, M B; Chen, B; Rao, C N R

2007-01-01

Pressure-induced phase transitions in the nanocrystals of ReO 3 with an average diameter of ∼12 nm have been investigated in detail by using synchrotron x-ray diffraction and the results compared with the literature data of bulk samples of ReO 3 . The study shows that the ambient-pressure cubic I phase (space group Pm3-barm) transforms to a monoclinic phase (space group C 2/c), then to a rhombohedral I phase (space group R3-barc), and finally to another rhombohedral phase (rhombohedral II, space group R3-barc) with increasing pressure over the 0.0-20.3 GPa range. The cubic I to monoclinic transition is associated with the largest volume change (∼5%), indicative of a reconstructive transition. The transition pressures are generally lower than those known for bulk ReO 3 . The cubic II (Im3-bar) or tetragonal (P4/mbm) phases do not occur at lower pressures. The nanocrystals are found to be more compressible than bulk ReO 3 . On decompression to ambient pressure, the structure does not revert back to the cubic I structure

A stress-induced phase transition model for semi-crystallize shape memory polymer

Science.gov (United States)

Guo, Xiaogang; Zhou, Bo; Liu, Liwu; Liu, Yanju; Leng, Jinsong

2014-03-01

The developments of constitutive models for shape memory polymer (SMP) have been motivated by its increasing applications. During cooling or heating process, the phase transition which is a continuous time-dependent process happens in semi-crystallize SMP and the various individual phases form at different temperature and in different configuration. Then, the transformation between these phases occurred and shape memory effect will emerge. In addition, stress applied on SMP is an important factor for crystal melting during phase transition. In this theory, an ideal phase transition model considering stress or pre-strain is the key to describe the behaviors of shape memory effect. So a normal distributed model was established in this research to characterize the volume fraction of each phase in SMP during phase transition. Generally, the experiment results are partly backward (in heating process) or forward (in cooling process) compared with the ideal situation considering delay effect during phase transition. So, a correction on the normal distributed model is needed. Furthermore, a nonlinear relationship between stress and phase transition temperature Tg is also taken into account for establishing an accurately normal distributed phase transition model. Finally, the constitutive model which taking the stress as an influence factor on phase transition was also established. Compared with the other expressions, this new-type model possesses less parameter and is more accurate. For the sake of verifying the rationality and accuracy of new phase transition and constitutive model, the comparisons between the simulated and experimental results were carried out.

Phase transitions in nuclear matter

International Nuclear Information System (INIS)

Glendenning, N.K.

1984-11-01

The rather general circumstances under which a phase transition in hadronic matter at finite temperature to an abnormal phase in which baryon effective masses become small and in which copious baryon-antibaryon pairs appear is emphasized. A preview is also given of a soliton model of dense matter, in which at a density of about seven times nuclear density, matter ceases to be a color insulator and becomes increasingly color conducting. 22 references

Electroweak physics and electron scattering

International Nuclear Information System (INIS)

Henley, E.M.; Hwang, W.Y.P.

1988-01-01

The electroweak theory is developed and applied to electron scattering from nucleons and light nuclei. It is shown that these scatterings can be used to test the standard theory and probe structure effects. 33 refs., 5 figs

Phase transitions and quantum entropy

International Nuclear Information System (INIS)

Arrachea, L.; Canosa, N.; Plastino, A.; Portesi, M.; Rossignoli, R.

1990-01-01

An examination is made of the possibility to predict phase transitions of the fundamental state of finite quantum system, knowing the quantum entropy of these states, defined on the basis of the information theory. (Author). 7 refs., 3 figs

An objective indicator for two-phase flow pattern transition

International Nuclear Information System (INIS)

Hervieu, E.; Seleghim, P. Jr.

1998-01-01

This work concerns the development of a methodology which objective is to characterize and diagnose two-phase flow regime transitions. The approach is based on the fundamental assumption that a transition flow is less stationary than a flow with an established regime. In a first time, the efforts focused on: the design and construction of an experimental loop, allowing to reproduce the main horizontal two-phase flow patterns, in a stable and controlled way; the design and construction of an electrical impedance probe, providing an imaged information of the spatial phase distribution in the pipe; the systematic study of the joint time-frequency and time-scale analysis methods, which permitted to define an adequate parameter quantifying the unstationarity degree. In a second time, in order to verify the fundamental assumption, a series of experiments were conducted, which objective was to demonstrate the correlation between unstationarity and regime transition. The unstationarity degree was quantified by calculating the Gabor's transform time-frequency covariance of the impedance probe signals. Furthermore, the phenomenology of each transition was characterized by the joint moments and entropy. The results clearly show that the regime transitions are correlated with local time-frequency covariance peaks, which demonstrates that these regime transitions are characterized by a loss of stationarity. Consequently, the time-frequency covariance constitutes an objective two-phase flow regime transition indicator. (author)

Multiple phase transitions in the generalized Curie-Weiss model

International Nuclear Information System (INIS)

Eisele, T.; Ellis, R.S.

1988-01-01

The generalized Curie-Weiss model is an extension of the classical Curie-Weiss model in which the quadratic interaction function of the mean spin value is replaced by a more general interaction function. It is shown that the generalized Curie-Weiss model can have a sequence of phase transitions at different critical temperatures. Both first-order and second-order phase transitions can occur, and explicit criteria for the two types are given. Three examples of generalized Curie-Weiss models are worked out in detail, including one example with infinitely many phase transitions. A number of results are derived using large-deviation techniques

Phase transitions in Pareto optimal complex networks.

Science.gov (United States)

Seoane, Luís F; Solé, Ricard

2015-09-01

The organization of interactions in complex systems can be described by networks connecting different units. These graphs are useful representations of the local and global complexity of the underlying systems. The origin of their topological structure can be diverse, resulting from different mechanisms including multiplicative processes and optimization. In spatial networks or in graphs where cost constraints are at work, as it occurs in a plethora of situations from power grids to the wiring of neurons in the brain, optimization plays an important part in shaping their organization. In this paper we study network designs resulting from a Pareto optimization process, where different simultaneous constraints are the targets of selection. We analyze three variations on a problem, finding phase transitions of different kinds. Distinct phases are associated with different arrangements of the connections, but the need of drastic topological changes does not determine the presence or the nature of the phase transitions encountered. Instead, the functions under optimization do play a determinant role. This reinforces the view that phase transitions do not arise from intrinsic properties of a system alone, but from the interplay of that system with its external constraints.

Geometry-induced phase transition in fluids: capillary prewetting.

Science.gov (United States)

Yatsyshin, Petr; Savva, Nikos; Kalliadasis, Serafim

2013-02-01

We report a new first-order phase transition preceding capillary condensation and corresponding to the discontinuous formation of a curved liquid meniscus. Using a mean-field microscopic approach based on the density functional theory we compute the complete phase diagram of a prototypical two-dimensional system exhibiting capillary condensation, namely that of a fluid with long-ranged dispersion intermolecular forces which is spatially confined by a substrate forming a semi-infinite rectangular pore exerting long-ranged dispersion forces on the fluid. In the T-μ plane the phase line of the new transition is tangential to the capillary condensation line at the capillary wetting temperature T(cw). The surface phase behavior of the system maps to planar wetting with the phase line of the new transition, termed capillary prewetting, mapping to the planar prewetting line. If capillary condensation is approached isothermally with T>T(cw), the meniscus forms at the capping wall and unbinds continuously, making capillary condensation a second-order phenomenon. We compute the corresponding critical exponent for the divergence of adsorption.

Polymorphic phase transitions: Macroscopic theory and molecular simulation.

Science.gov (United States)

Anwar, Jamshed; Zahn, Dirk

2017-08-01

Transformations in the solid state are of considerable interest, both for fundamental reasons and because they underpin important technological applications. The interest spans a wide spectrum of disciplines and application domains. For pharmaceuticals, a common issue is unexpected polymorphic transformation of the drug or excipient during processing or on storage, which can result in product failure. A more ambitious goal is that of exploiting the advantages of metastable polymorphs (e.g. higher solubility and dissolution rate) while ensuring their stability with respect to solid state transformation. To address these issues and to advance technology, there is an urgent need for significant insights that can only come from a detailed molecular level understanding of the involved processes. Whilst experimental approaches at best yield time- and space-averaged structural information, molecular simulation offers unprecedented, time-resolved molecular-level resolution of the processes taking place. This review aims to provide a comprehensive and critical account of state-of-the-art methods for modelling polymorph stability and transitions between solid phases. This is flanked by revisiting the associated macroscopic theoretical framework for phase transitions, including their classification, proposed molecular mechanisms, and kinetics. The simulation methods are presented in tutorial form, focusing on their application to phase transition phenomena. We describe molecular simulation studies for crystal structure prediction and polymorph screening, phase coexistence and phase diagrams, simulations of crystal-crystal transitions of various types (displacive/martensitic, reconstructive and diffusive), effects of defects, and phase stability and transitions at the nanoscale. Our selection of literature is intended to illustrate significant insights, concepts and understanding, as well as the current scope of using molecular simulations for understanding polymorphic

Extracellular ice phase transitions in insects.

Science.gov (United States)

Hawes, T C

2014-01-01

At temperatures below their temperature of crystallization (Tc), the extracellular body fluids of insects undergo a phase transition from liquid to solid. Insects that survive the transition to equilibrium (complete freezing of the body fluids) are designated as freeze tolerant. Although this phenomenon has been reported and described in many Insecta, current nomenclature and theory does not clearly delineate between the process of transition (freezing) and the final solid phase itself (the frozen state). Thus freeze tolerant insects are currently, by convention, described in terms of the temperature at which the crystallization of their body fluids is initiated, Tc. In fact, the correct descriptor for insects that tolerate freezing is the temperature of equilibrium freezing, Tef. The process of freezing is itself a separate physical event with unique physiological stresses that are associated with ice growth. Correspondingly there are a number of insects whose physiological cryo-limits are very specifically delineated by this transitional envelope. The distinction also has considerable significance for our understanding of insect cryobiology: firstly, because the ability to manage endogenous ice growth is a fundamental segregator of cryotype; and secondly, because our understanding of internal ice management is still largely nascent.

Precision electroweak physics at LEP

Energy Technology Data Exchange (ETDEWEB)

Mannelli, M.

1994-12-01

Copious event statistics, a precise understanding of the LEP energy scale, and a favorable experimental situation at the Z{sup 0} resonance have allowed the LEP experiments to provide both dramatic confirmation of the Standard Model of strong and electroweak interactions and to place substantially improved constraints on the parameters of the model. The author concentrates on those measurements relevant to the electroweak sector. It will be seen that the precision of these measurements probes sensitively the structure of the Standard Model at the one-loop level, where the calculation of the observables measured at LEP is affected by the value chosen for the top quark mass. One finds that the LEP measurements are consistent with the Standard Model, but only if the mass of the top quark is measured to be within a restricted range of about 20 GeV.

Electroweak Physics at the Tevatron and LHC: Theoretical Status and Perspectives

OpenAIRE

Baur, U.

2005-01-01

I review the status of theoretical calculations relevant for electroweak physics at the Tevatron and LHC and discuss future directions. I also give a brief overview of current electroweak data and discuss future expectations.

No Hawking-Page phase transition in three dimensions

International Nuclear Information System (INIS)

Myung, Y.S.

2005-01-01

We investigate whether or not the Hawking-Page phase transition is possible to occur in three dimensions. Starting with the simplest class of Lanczos-Lovelock action, thermodynamic behavior of all AdS-type black holes without charge falls into two classes: Schwarzschild-AdS black holes in even dimensions and Chern-Simons black holes in odd dimensions. The former class can provide the Hawking-Page transition between Schwarzschild-AdS black holes and thermal AdS space. On the other hand, the latter class is exceptional and thus the Hawking-Page transition is hard to occur. In three dimensions, a second-order phase transition might occur between the non-rotating BTZ black hole and the massless BTZ black hole (thermal AdS space), instead of the first-order Hawking-Page transition between the non-rotating BTZ black hole and thermal AdS space

On the catalysis of the electroweak vacuum decay by black holes at high temperature

Science.gov (United States)

Canko, D.; Gialamas, I.; Jelic-Cizmek, G.; Riotto, A.; Tetradis, N.

2018-04-01

We study the effect of primordial black holes on the classical rate of nucleation of AdS regions within the standard electroweak vacuum at high temperature. We base our analysis on the assumption that, at temperatures much higher than the Hawking temperature, the main effect of the black hole is to distort the Higgs configuration dominating the transition to the new vacuum. We estimate the barrier for the transition by the ADM mass of this configuration, computed through the temperature-corrected Higgs potential. We find that the exponential suppression of the nucleation rate can be reduced significantly, or even eliminated completely, in the black-hole background if the Standard Model Higgs is coupled to gravity through the renormalizable term ξ R h^2.

Dynamical phase transitions in quantum mechanics

International Nuclear Information System (INIS)

Rotter, Ingrid

2012-01-01

1936 Niels Bohr: In the atom and in the nucleus we have indeed to do with two extreme cases of mechanical many-body problems for which a procedure of approximation resting on a combination of one-body problems, so effective in the former case, loses any validity in the latter where we, from the very beginning, have to do with essential collective aspects of the interplay between the constituent particles. 1963: Maria Goeppert-Mayer and J. Hans D. Jensen received the Nobel Prize in Physics for their discoveries concerning nuclear shell structure. State of the art 2011: - The nucleus is an open quantum system described by a non-Hermitian Hamilton operator with complex eigenvalues. The eigenvalues may cross in the complex plane ('exceptional points'), the phases of the eigenfunctions are not rigid in approaching the crossing points and the widths bifurcate. By this, a dynamical phase transition occurs in the many-level system. The dynamical phase transition starts at a critical value of the level density. Hence the properties of he low-lying nuclear states (described well by the shell model) and those of highly excited nuclear states (described by random ensembles) differ fundamentally from one another. The statement of Niels Bohr for compound nucleus states at high level density is not in contradiction to the shell-model description of nuclear (and atomic) states at low level density. Dynamical phase transitions are observed experimentally in different systems, including PT-symmetric ones, by varying one or more parameters

The Kibble-Zurek mechanism in phase transitions of non-equilibrium systems

Science.gov (United States)

Cheung, Hil F. H.; Patil, Yogesh S.; Date, Aditya G.; Vengalattore, Mukund

2017-04-01

We experimentally realize a driven-dissipative phase transition using a mechanical parametric amplifier to demonstrate key signatures of a second order phase transition, including a point where the susceptibilities and relaxation time scales diverge, and where the system exhibits a spontaneous breaking of symmetry. Though reminiscent of conventional equilibrium phase transitions, it is unclear if such driven-dissipative phase transitions are amenable to the conventional Landau-Ginsburg-Wilson paradigm, which relies on concepts of scale invariance and universality, and recent work has shown that such phase transitions can indeed lie beyond such conventional universality classes. By quenching the system past the critical point, we investigate the dynamics of the emergent ordered phase and find that our measurements are in excellent agreement with the Kibble-Zurek mechanism. In addition to verifying the Kibble-Zurek hypothesis in driven-dissipative phase transitions for the first time, we also demonstrate that the measured critical exponents accurately reflect the interplay between intrinsic coherent dynamics and environmental correlations, showing a clear departure from mean field exponents in the case of non-Markovian system-bath interactions. We further discuss how reservoir engineering and the imposition of artificial environmental correlations can result in the stabilization of novel many-body quantum phases and aid in the creation of exotic non-equilibrium states of matter.

Structural phase transitions in niobium oxide nanocrystals

Science.gov (United States)

Yuvakkumar, R.; Hong, Sun Ig

2015-09-01

Niobium oxide nanocrystals were successfully synthesized employing the green synthesis method. Phase formation, microstructure and compositional properties of 1, 4 and 7 days incubation treated samples after calcinations at 450 °C were examined using X-ray diffraction, Raman, photoluminescence (PL), infrared, X-ray photoelectron spectra and transmission electron microscopic characterizations. It was observed that phase formation of Nb2O5 nanocrystals was dependent upon the incubation period required to form stable metal oxides. The characteristic results clearly revealed that with increasing incubation and aging, the transformation of cubic, orthorhombic and monoclinic phases were observed. The uniform heating at room temperature (32 °C) and the ligation of niobium atoms due to higher phenolic constituents of utilized rambutan during aging processing plays a vital role in structural phase transitions in niobium oxide nanocrystals. The defects over a period of incubation and the intensities of the PL spectra changing over a period of aging were related to the amount of the defects induced by the phase transition.

Phase transitions in multiplicative competitive processes

International Nuclear Information System (INIS)

Shimazaki, Hideaki; Niebur, Ernst

2005-01-01

We introduce a discrete multiplicative process as a generic model of competition. Players with different abilities successively join the game and compete for finite resources. Emergence of dominant players and evolutionary development occur as a phase transition. The competitive dynamics underlying this transition is understood from a formal analogy to statistical mechanics. The theory is applicable to bacterial competition, predicting novel population dynamics near criticality

Probing phase transitions via energetic nuclear collisions

International Nuclear Information System (INIS)

Lukacs, B.; Csernai, L.P.

1983-07-01

The possible effects of the nucleon-quark phase transition on the dynamics of heavy ion collisions are discussed. It is shown that the formation of the quark phase can be expected at recent experiments. Nevertheless, the compressibility of the two-phase mixture remains relatively low, thus the quark phase remains limited in both space and time, and the observables are not strongly affected. (author)

High pressure structural phase transitions of TiO2 nanomaterials

International Nuclear Information System (INIS)

Li Quan-Jun; Liu Bing-Bing

2016-01-01

Recently, the high pressure study on the TiO 2 nanomaterials has attracted considerable attention due to the typical crystal structure and the fascinating properties of TiO 2 with nanoscale sizes. In this paper, we briefly review the recent progress in the high pressure phase transitions of TiO 2 nanomaterials. We discuss the size effects and morphology effects on the high pressure phase transitions of TiO 2 nanomaterials with different particle sizes, morphologies, and microstructures. Several typical pressure-induced structural phase transitions in TiO 2 nanomaterials are presented, including size-dependent phase transition selectivity in nanoparticles, morphology-tuned phase transition in nanowires, nanosheets, and nanoporous materials, and pressure-induced amorphization (PIA) and polyamorphism in ultrafine nanoparticles and TiO 2 -B nanoribbons. Various TiO 2 nanostructural materials with high pressure structures are prepared successfully by high pressure treatment of the corresponding crystal nanomaterials, such as amorphous TiO 2 nanoribbons, α -PbO 2 -type TiO 2 nanowires, nanosheets, and nanoporous materials. These studies suggest that the high pressure phase transitions of TiO 2 nanomaterials depend on the nanosize, morphology, interface energy, and microstructure. The diversity of high pressure behaviors of TiO 2 nanomaterials provides a new insight into the properties of nanomaterials, and paves a way for preparing new nanomaterials with novel high pressure structures and properties for various applications. (topical review)

Theoretical description of the properties of magnetization fluctuations in the vicinity of phase transition from paramagnetic phase to ferromagnetic phase with domain structure

International Nuclear Information System (INIS)

Wasilewski, W.

1983-08-01

This paper presents a theoretical description of the phase transition from a paramagnetic phase P to the homogeneous and domain structure ferromagnetic phases within the phenomenological theory of phase transitions

Isotropic–Nematic Phase Transitions in Gravitational Systems

Energy Technology Data Exchange (ETDEWEB)

Roupas, Zacharias; Kocsis, Bence [Institute of Physics, Eötvös University, Pázmány P. s. 1/A, Budapest, 1117 (Hungary); Tremaine, Scott [Institute for Advanced Study, Princeton, NJ 08540 (United States)

2017-06-20

We examine dense self-gravitating stellar systems dominated by a central potential, such as nuclear star clusters hosting a central supermassive black hole. Different dynamical properties of these systems evolve on vastly different timescales. In particular, the orbital-plane orientations are typically driven into internal thermodynamic equilibrium by vector resonant relaxation before the orbital eccentricities or semimajor axes relax. We show that the statistical mechanics of such systems exhibit a striking resemblance to liquid crystals, with analogous ordered-nematic and disordered-isotropic phases. The ordered phase consists of bodies orbiting in a disk in both directions, with the disk thickness depending on temperature, while the disordered phase corresponds to a nearly isotropic distribution of the orbit normals. We show that below a critical value of the total angular momentum, the system undergoes a first-order phase transition between the ordered and disordered phases. At a critical point, the phase transition becomes second order, while for higher angular momenta there is a smooth crossover. We also find metastable equilibria containing two identical disks with mutual inclinations between 90° and 180°.

Electroweak symmetry breaking in supersymmetric gauge-Higgs unification models

International Nuclear Information System (INIS)

Choi, Kiwoon; Jeong, Kwang-Sik; Okumura, Ken-ichi; Haba, Naoyuki; Shimizu, Yasuhiro; Yamaguchi, Masahiro

2004-01-01

We examine the Higgs mass parameters and electroweak symmetry breaking in supersymmetric orbifold field theories in which the 4-dimensional Higgs fields originate from higher-dimensional gauge supermultiplets. It is noted that such gauge-Higgs unification leads to a specific boundary condition on the Higgs mass parameters at the compactification scale, which is independent of the details of supersymmetry breaking mechanism. With this boundary condition, phenomenologically viable parameter space of the model is severely constrained by the condition of electroweak symmetry breaking for supersymmetry breaking scenarios which can be realized naturally in orbifold field theories. For instance, if it is assumed that the 4-dimensional effective theory is the minimal supersymmetric standard model with supersymmetry breaking parameters induced by the Scherk-Schwarz mechanism, a correct electroweak symmetry breaking can not be achieved for reasonable range of parameters of the model, even when one includes additional contributions to the Higgs mass parameters from the auxiliary component of 4-dimensional conformal compensator. However if there exists a supersymmetry breaking mediated by brane superfields, sizable portion of the parameter space can give a correct electroweak symmetry breaking. (author)

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.

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.

Isostructural magnetic phase transition and magnetocaloric effect in Ising antiferromagnet

International Nuclear Information System (INIS)

Lavanov, G.Yu; Kalita, V.M.; Loktev, V.M.

2014-01-01

It is shown that the external magnetic field induced isostructural I st order magnetic phase transition between antiferromagnetic phases with different antiferromagnetic vector values is associated with entropy. It is found, that depending on temperature the entropy jump and the related heat release change their sign at this transition point. In the low-temperature region of metamagnetic I st order phase tensition the entropy jump is positive, and in the triple point region this jump for isostructural magnetic transition is negative

Phase transitions and critical phenomena

CERN Document Server

Domb, Cyril

2001-01-01

The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. It has moved into a central place in condensed matter studies.Statistical physics, and more specifically, the theory of transitions between states of matter, more or less defines what we know about 'everyday' matter and its transformations.The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable in

An objective indicator for two-phase flow pattern transition

International Nuclear Information System (INIS)

Hervieua, E.; Seleghim, P. Jr.

1998-01-01

This work concerns the development of a methodology the objective of which is to characterize and diagnose two-phase flow regime transitions. The approach is based on the fundamental assumption that a transition flow is less stationary than a flow with an established regime. During the first time, the efforts focused on: (1) the design and construction of an experimental loop, allowing to reproduce the main horizontal two-phase flow patterns, in a stable and controlled way; (2) the design and construction of an electrical impedance probe, providing an imaged information of the spatial phase distribution in the pipe; and (3) the systematic study of the joint time-frequency and time-scale analysis methods, which permitted to define an adequate parameter quantifying the unstationarity degree. During the second time, in order to verify the fundamental assumption, a series of experiments were conducted, the objective of which was to demonstrate the correlation between unstationarity and regime transition. The unstationarity degree was quantified by calculating the Gabor's transform time-frequency covariance of the impedance probe signals. Furthermore, the phenomenology of each transition was characterized by the joint moments and entropy. The results clearly show that the regime transitions are correlated with local time-frequency covariance peaks, which demonstrates that these regime transitions are characterized by a loss of stationarity. Consequently, the time-frequency covariance constitutes an objective two-phase flow regime transition indicator. (orig.)

Discontinuity of maximum entropy inference and quantum phase transitions

International Nuclear Information System (INIS)

Chen, Jianxin; Ji, Zhengfeng; Yu, Nengkun; Zeng, Bei; Li, Chi-Kwong; Poon, Yiu-Tung; Shen, Yi; Zhou, Duanlu

2015-01-01

In this paper, we discuss the connection between two genuinely quantum phenomena—the discontinuity of quantum maximum entropy inference and quantum phase transitions at zero temperature. It is shown that the discontinuity of the maximum entropy inference of local observable measurements signals the non-local type of transitions, where local density matrices of the ground state change smoothly at the transition point. We then propose to use the quantum conditional mutual information of the ground state as an indicator to detect the discontinuity and the non-local type of quantum phase transitions in the thermodynamic limit. (paper)

Phase transitions in (NH4)2MoO2F4 crystal

Science.gov (United States)

Krylov, Alexander; Laptash, Natalia; Vtyurin, Alexander; Krylova, Svetlana

2016-11-01

The mechanisms of temperature and high pressure phase transitions have been studied by Raman spectroscopy. Room temperature (295 K) experiments under high hydrostatic pressure up to 3.6 GPa for (NH4)2 MoO2 F4 have been carried out. Experimental data indicates a phase transition into a new high-pressure phase for (NH4)2 MoO2 F4 at 1.2 GPa. This phase transition is related to the ordering anion octahedron groups [MoO2 F4]2- and is not associated with ammonium group. Raman spectra of small non-oriented crystals ranging from 10 to 350 K have been observed. The experiment shows anion groups [MoO2 F4]2- and ammonium in high temperature phase are disordered. The phase transition at T1 = 269.8 K is of the first-order, close to the tricritical point. The first temperature phase transition is related to the ordering anion octahedron groups [MoO2 F4]2-. Second phase transitions T2 = 180 K are associated with the ordering of ammonium. The data presented within this study demonstrate that 2D correlation analysis combined with traditional Raman spectroscopy are powerful tool to study phase transitions in the crystals.

Transitional region of phase transitions in nuclear models

Energy Technology Data Exchange (ETDEWEB)

Kotze, A A

1988-01-01

The phase transition in an exactly solvable nuclear model, the Lipkin model, is scrutinised, first using Hartree-Fock methods or the plain mean flield approximation, and then using projected wave functions. It turns out that the plain mean field is not reliable in the transitional region. Although the projection methods give better resutls in the transitional region, it leads to spurious singularities. While the energy of the projection before variation is slightly better than its projection after variation counterpart, the perfomance of the wave function is considerably worse in the transitional region. The model's wave function undergoes dramatic changes in the transitional region. The mechanism that brings about these changes is studied within a model Hamiltonian that can reproduce the Lipkin model mathematically. It turns out that the numerous exceptional points found in the transitional region, bring about the change of the ground state wave function. Exceptional points are associated with level crossings in the complex plane. These level crossings can be seen as level repulsions in the spectrum. Level repulsion and a sensitive dependence of the system on some external parameter are characteristics of chaotic behaviour. These two features are found in the transitional region of the Lipkin model. In order to study chaos, one has to resort to a statistical analysis. A measure of the chaotic behaviour of systems, the ..delta../sub 3/ statistic, is introduced. The results show that the Lipkin model is harmonic, even in the transitional region. For the Lipkin model the exceptional points are regularly distributed in the complex plane. In a total chaotic system the points would be randomly distributed.

Phase Transition Behavior in a Neutral Evolution Model

Science.gov (United States)

King, Dawn; Scott, Adam; Maric, Nevena; Bahar, Sonya

2014-03-01

The complexity of interactions among individuals and between individuals and the environment make agent based modeling ideal for studying emergent speciation. This is a dynamically complex problem that can be characterized via the critical behavior of a continuous phase transition. Concomitant with the main tenets of natural selection, we allow organisms to reproduce, mutate, and die within a neutral phenotype space. Previous work has shown phase transition behavior in an assortative mating model with variable fitness landscapes as the maximum mutation size (μ) was varied (Dees and Bahar, 2010). Similarly, this behavior was recently presented in the work of Scott et al. (2013), even on a completely neutral landscape, for bacterial-like fission as well as for assortative mating. Here we present another neutral model to investigate the `critical' phase transition behavior of three mating types - assortative, bacterial, and random - in a phenotype space as a function of the percentage of random death. Results show two types of phase transitions occurring for the parameters of the population size and the number of clusters (an analogue of species), indicating different evolutionary dynamics for system survival and clustering. This research was supported by funding from: University of Missouri Research Board and James S. McDonnell Foundation.

Temperature-Controlled High-Speed AFM: Real-Time Observation of Ripple Phase Transitions.

Science.gov (United States)

Takahashi, Hirohide; Miyagi, Atsushi; Redondo-Morata, Lorena; Scheuring, Simon

2016-11-01

With nanometer lateral and Angstrom vertical resolution, atomic force microscopy (AFM) has contributed unique data improving the understanding of lipid bilayers. Lipid bilayers are found in several different temperature-dependent states, termed phases; the main phases are solid and fluid phases. The transition temperature between solid and fluid phases is lipid composition specific. Under certain conditions some lipid bilayers adopt a so-called ripple phase, a structure where solid and fluid phase domains alternate with constant periodicity. Because of its narrow regime of existence and heterogeneity ripple phase and its transition dynamics remain poorly understood. Here, a temperature control device to high-speed atomic force microscopy (HS-AFM) to observe dynamics of phase transition from ripple phase to fluid phase reversibly in real time is developed and integrated. Based on HS-AFM imaging, the phase transition processes from ripple phase to fluid phase and from ripple phase to metastable ripple phase to fluid phase could be reversibly, phenomenologically, and quantitatively studied. The results here show phase transition hysteresis in fast cooling and heating processes, while both melting and condensation occur at 24.15 °C in quasi-steady state situation. A second metastable ripple phase with larger periodicity is formed at the ripple phase to fluid phase transition when the buffer contains Ca 2+ . The presented temperature-controlled HS-AFM is a new unique experimental system to observe dynamics of temperature-sensitive processes at the nanoscopic level. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electroweak physics from D0

International Nuclear Information System (INIS)

Roe, N.A.

1993-05-01

The D0 detector was recently commissioned at the Tevatron p bar p collider and is presently taking data. Preliminary results from D0 are presented on properties of the W and Z electroweak gauge bosons, using final states containing electrons and muons

Electroweak chiral Lagrangian from the topcolor-assisted technicolor model with nontrivial technicolor fermion condensation and walking

International Nuclear Information System (INIS)

Ge Fengjun; Jiang Shaozhou; Wang Qing

2011-01-01

The electroweak chiral Lagrangian for the topcolor-assisted technicolor model proposed by K. Lane, which uses nontrivial patterns of techniquark condensation and walking, was investigated in this study. We found that the features of the model are qualitatively similar to those of Lane's previous natural topcolor-assisted technicolor prototype model, but there is no limit on the upper bound of the Z ' mass. We discuss the phase structure and possible walking behavior of the model. We obtained the values of all coefficients of the electroweak chiral Lagrangian up to an order of p 4 . We show that although the walking effect reduces the S parameter to half its original value, it maintains an order of 2. Moreover, a special hypercharge arrangement is needed to achieve further reductions in its value.

Electroweak interactions on the lattice

International Nuclear Information System (INIS)

Kieu, T.D.

1994-07-01

It is shown that the lattice fermion doubling phenomenon is connected to the chiral anomaly which is unique to the electroweak interactions. The chiral anomaly is the breaking of chiral gauge symmetry at the quantum level due to the quantum fluctuations. Such breaking, however, is undesirable and to be avoided. The preservation of gauge symmetry imposes stringent constraints on acceptable chiral gauge theory. It is argued that the constraints are unnecessary because the conventional quantization of chiral gauge theory has missed out some crucial contributions of the chiral interactions. The corrected quantization yields consistent theory in which there is no gauge anomaly and in which various mass terms can be introduced with neither the loss of gauge invariance nor the need for the Higgs mechanism. The new quantization also provide a solution to the difficulty of how to model the electroweak interactions on the lattice. 9 refs. 1 fig

Phase transition from strong-coupling expansion

International Nuclear Information System (INIS)

Polonyi, J.; Szlachanyi, K.

1982-01-01

Starting with quarkless SU(2) lattice gauge theory and using the strong-coupling expansion we calculate the action of the effective field theory which corresponds to the thermal Wilson loop. This effective action makes evident that the quark liberating phase transition traces back to the spontaneous breaking of a global Z(2) symmetry group. It furthermore describes both phases qualitatively. (orig.)

Signals of a phase transition in nuclear breakup

International Nuclear Information System (INIS)

Campi, X.

1987-01-01

We show that nuclei break up like finite systems that exhibit a clean phase transition in infinite size. This is done by studying conditional moments of the fragment multiplicities, the largest fragment size produced by event and its fluctuations. The nature of this smooth phase transition cannot be determined from the available experimental data. The ''critical point'' is reached when the energy deposited in the nucleus is 90% of its binding energy

Studying the Electroweak Sector with the ATLAS Detector

CERN Document Server

Spalla, Margherita; The ATLAS collaboration

2018-01-01

(as received from the Speaker Committee. W mass removed from the presentation later on, as discussed in separate talk.) The large integrated luminosities that are available at the LHC, allow to test the gauge structure of the electroweak sector of the Standard Model to highest precision. In this talk, we review the latest results of the ATLAS collaboration involving di-boson and multiboson final states, the electroweak production of vector bosons as well as their constraints of effective field theory operators. Another approach to test the consistency of the electroweak sector is via precision measurements. ATLAS has published a first high precision measurement of the W boson mass, a first measurement of the tau-polarization in Z events as well as a three dimensional cross-section measurement of the Drell-Yan process. The latter allows for the extraction of the forward-backward asymmetry that can be interpreted as a measurement of the weak mixing angle. These results will be presented and discussed.

Optical study of phase transitions in single-crystalline RuP

Science.gov (United States)

Chen, R. Y.; Shi, Y. G.; Zheng, P.; Wang, L.; Dong, T.; Wang, N. L.

2015-03-01

RuP single crystals of MnP-type orthorhombic structure were synthesized by the Sn flux method. Temperature-dependent x-ray diffraction measurements reveal that the compound experiences two structural phase transitions, which are further confirmed by enormous anomalies shown in temperature-dependent resistivity and magnetic susceptibility. Particularly, the resistivity drops monotonically upon temperature cooling below the second transition, indicating that the material shows metallic behavior, in sharp contrast with the insulating ground state of polycrystalline samples. Optical conductivity measurements were also performed in order to unravel the mechanism of these two transitions. The measurement revealed a sudden reconstruction of band structure over a broad energy scale and a significant removal of conducting carriers below the first phase transition, while a charge-density-wave-like energy gap opens below the second phase transition.

Time-delay-induced phase-transition to synchrony in coupled bursting neurons

Science.gov (United States)

Adhikari, Bhim Mani; Prasad, Awadhesh; Dhamala, Mukeshwar

2011-06-01

Signal transmission time delays in a network of nonlinear oscillators are known to be responsible for a variety of interesting dynamic behaviors including phase-flip transitions leading to synchrony or out of synchrony. Here, we uncover that phase-flip transitions are general phenomena and can occur in a network of coupled bursting neurons with a variety of coupling types. The transitions are marked by nonlinear changes in both temporal and phase-space characteristics of the coupled system. We demonstrate these phase-transitions with Hindmarsh-Rose and Leech-Heart interneuron models and discuss the implications of these results in understanding collective dynamics of bursting neurons in the brain.

Ring diagrams and phase transitions

International Nuclear Information System (INIS)

Takahashi, K.

1986-01-01

Ring diagrams at finite temperatures carry most infrared-singular parts among Feynman diagrams. Their effect to effective potentials are in general so significant that one must incorporate them as well as 1-loop diagrams. The author expresses these circumstances in some examples of supercooled phase transitions

Electrostatic Effects in Phase Transitions of Biomembranes between Cubic Phases and Lamellar Liquid-Crystalline (Lα) phase

Science.gov (United States)

Masum, Shah Md.; Li, Shu Jie; Tamba, Yukihiro; Yamashita, Yuko; Yamazaki, Masahito

2004-04-01

Elucidation of the mechanisms of transitions between cubic phase and liquid-crystalline (Lα) phase, and between different IPMS cubic phases, are essential for understanding of dynamics of biomembranes and topological transformation of lipid membranes. Recently, we found that electrostatic interactions due to surface charges of lipid membranes induce transition between cubic phase and Lα phase, and between different IPMS cubic phases. As electrostatic interactions increase, the most stable phase of a monoolein (MO) membrane changes: Q224 ⇒ Q229 ⇒ Lα. We also found that a de novo designed peptide partitioning into electrically neutral lipid membrane changed the phase stability of the MO membranes. As peptide-1 concentration increased, the most stable phase of a MO membrane changes: Q224 ⇒ Q229 ⇒Lα. In both cases, the increase in the electrostatic repulsive interaction greatly reduced the absolute value of spontaneous curvature of the MO monolayer membrane. We also investigated factors such as poly (L-lysine) and osmotic stress to control structure and phase stability of DOPA/MO membranes. Based on these results, we discuss the mechanism of the effect of electrostatic interactions on the stability of cubic phase.