Chiral Magnetic Effect and Chiral Phase Transition
Institute of Scientific and Technical Information of China (English)
FU Wei-Jie; LIU Yu-Xin; WU Yue-Liang
2011-01-01
We study the influence of the chiral phase transition on the chiral magnetic effect.The azimuthal chargeparticle correlations as functions of the temperature are calculated.It is found that there is a pronounced cusp in the correlations as the temperature reaches its critical value for the QCD phase transition.It is predicted that there will be a drastic suppression of the charge-particle correlations as the collision energy in RHIC decreases to below a critical value.We show then the azimuthal charge-particle correlations can be the signal to identify the occurrence of the QCD phase transitions in RHIC energy scan experiments.
Neutrino Oscillation Induced by Chiral Phase Transition
Institute of Scientific and Technical Information of China (English)
MU Cheng-Fu; SUN Gao-Feng; ZHUANG Peng-Fei
2009-01-01
Electric charge neutrality provides a relationship between chiral dynamics and neutrino propagation in compact stars.Due to the sudden drop of the electron density at the first-order chiral phase transition,the oscillation for low energy neutrinos is significant and can be regarded as a signature of chiral symmetry restoration in the core of compact stars.
Interplay between chiral and deconfinement phase transitions
Directory of Open Access Journals (Sweden)
Mukherjee T.K.
2011-04-01
Full Text Available By using the dressed Polyakov loop or dual chiral condensate as an equivalent order parameter of the deconfinement phase transition, we investigate the relation between the chiral and deconfinement phase transitions at finite temperature and density in the framework of three-flavor Nambu-Jona-Lasinio (NJL model. It is found that in the chiral limit, the critical temperature for chiral phase transition coincides with that of the dressed Polyakov loop in the whole (T,µ plane. In the case of explicit chiral symmetry breaking, it is found that the phase transitions are flavor dependent. For each flavor, the transition temperature for chiral restoration $T^{mathcal{X}}_c$ is smaller than that of the dressed Polyakov loop $T^{mathcal{D}}_c$ in the low baryon density region where the transition is a crossover, and, the two critical temperatures coincide in the high baryon density region where the phase transition is of first order. Therefore, there are two critical end points, i.e, $T^{u,d}_{CEP}$ and $T^{s}_{CEP}$ at finite density. We also explain the feature of $T^{mathcal{X}}_c$ = $T^{mathcal{D}}_c$ in the case of 1st and 2nd order phase transitions, and $T^{mathcal{X}}_c$ < $T^{mathcal{D}}_c$ in the case of crossover, and expect this feature is general and can be extended to full QCD theory.
Interplay between chiral and deconfinement phase transitions
Xu, Fukun; Chen, Huan; Huang, Mei
2011-01-01
By using the dressed Polyakov loop or dual chiral condensate as an equivalent order parameter of the deconfinement phase transition, we investigate the relation between the chiral and deconfinement phase transitions at finite temperature and density in the framework of three-flavor Nambu--Jona-Lasinio (NJL) model. It is found that in the chiral limit, the critical temperature for chiral phase transition coincides with that of the dressed Polyakov loop in the whole $(T,\\mu)$ plane. In the case of explicit chiral symmetry breaking, it is found that the phase transitions are flavor dependent. For each flavor, the transition temperature for chiral restoration $T_c^{\\chi}$ is smaller than that of the dressed Polyakov loop $T_c^{{\\cal D}}$ in the low baryon density region where the transition is a crossover, and, the two critical temperatures coincide in the high baryon density region where the phase transition is of first order. Therefore, there are two critical end points, i.e, $T_{CEP}^{u,d}$ and $T_{CEP}^{s}$ a...
Chiral phase transition from string theory.
Parnachev, Andrei; Sahakyan, David A
2006-09-15
The low energy dynamics of a certain D-brane configuration in string theory is described at weak t'Hooft coupling by a nonlocal version of the Nambu-Jona-Lasinio model. We study this system at finite temperature and strong t'Hooft coupling, using the string theory dual. We show that for sufficiently low temperatures chiral symmetry is broken, while for temperatures larger then the critical value, it gets restored. We compute the latent heat and observe that the phase transition is of the first order.
Chirality effects on 2D phase transitions
DEFF Research Database (Denmark)
Scalas, E.; Brezesinski, G.; Möhwald, H.;
1996-01-01
investigated pressures. However, at both temperatures, there is a sharp phase transition from a low-pressure phase, in which the molecules are tilted towards nearest neighbours (NN) and the distortion azimuth also points towards NN, to a high-pressure phase, in which the molecules are tilted towards next......Monolayers of the racemate and pure enantiomers of 1-hexadecyl-glycerol were investigated by grazing incidence X-ray diffraction (GID) at 5 and 20 degrees C on compression from 0 mN m(-1) to pressures greater than 30 mN m(-1). The racemate Lattice is centred-rectangular for both temperatures at all......-nearest neighbours (NNN) and an NNN-distorted lattice is observed. At 5 degrees C, the transition pressure is 15 mN m(-1), whereas at 20 degrees C it is 18 mN m(-1). Chirality destroys this transition: the pure enantiomer always exhibits an oblique lattice with tilted molecules, and the azimuths of tilt...
Chiral and Deconfining Phase Transitions from Holographic QCD Study
Fang, Zhen; Li, Danning
2015-01-01
A first attempt to accommodate the chiral and deconfining phase transitions of QCD in the bottom-up holographic framework is given. We constrain the relation between dilaton field $\\phi$ and metric warp factor $A_e$ and get several reasonable models in the Einstein-Dilaton system. Using the potential reconstruction approach, we solve the corresponding gravity background. Then we fit the background-related parameters by comparing the equation of state with the two-flavor lattice QCD results. After that we study the temperature dependent behavior of Polyakov loop and chiral condensate under those background solutions. We find that the results are in good agreement with the two-flavor lattice results. All the studies about the equation of state, the Polyakov loop and the chiral condensate signal crossover behavior of the phase transitions, which is consistent with the current understanding on the QCD phase transitions with physical quark mass. Furthermore, the extracted transition temperatures are comparable wit...
Chiral phase transition in QED$_3$ at finite temperature
Wei, Wei; Zong, Hong-Shi
2016-01-01
Chiral phase transition in (2+1)-dimensional quantum electrodynamics (QED$_3$) at finite temperature is investigated in the framework of truncated Dyson-Schwinger equations (DSEs). We go beyond the widely used instantaneous approximation and adopt a method that retains the full frequency dependence of the fermion self-energy. We also take further step to include the effects of wave-function renormalizations and introduce a minimal dressing of the bare vertex. Finally, with the more complete solutions of the truncated DSEs, we revisit the study of chiral phase transition in finite-temperature QED$_3$.
On SU(3) effective models and chiral phase-transition
Tawfik, Abdel Nasser
2015-01-01
The sensitivity of Polyakov Nambu-Jona-Lasinio (PNJL) model as an effective theory of quark dynamics to chiral symmetry has been utilized in studying the QCD phase-diagram. Also, Poyakov linear sigma-model (PLSM), in which information about the confining glue sector of the theory was included through Polyakov-loop potential. Furthermore, from quasi-particle model (QPM), the gluonic sector of QPM is integrated to LSM in order to reproduce recent lattice calculations. We review PLSM, QLSM, PNJL and HRG with respect to their descriptions for the chiral phase-transition. We analyse chiral order-parameter M(T), normalized net-strange condensate Delta_{q,s}(T) and chiral phase-diagram and compare the results with lattice QCD. We conclude that PLSM works perfectly in reproducing M(T) and Delta_{q,s}(T). HRG model reproduces Delta_{q,s}(T), while PNJL and QLSM seem to fail. These differences are present in QCD chiral phase-diagram. PLSM chiral boundary is located in upper band of lattice QCD calculations and agree we...
On SU(3 Effective Models and Chiral Phase Transition
Directory of Open Access Journals (Sweden)
Abdel Nasser Tawfik
2015-01-01
Full Text Available Sensitivity of Polyakov Nambu-Jona-Lasinio (PNJL model and Polyakov linear sigma-model (PLSM has been utilized in studying QCD phase-diagram. From quasi-particle model (QPM a gluonic sector is integrated into LSM. The hadron resonance gas (HRG model is used in calculating the thermal and dense dependence of quark-antiquark condensate. We review these four models with respect to their descriptions for the chiral phase transition. We analyze the chiral order parameter, normalized net-strange condensate, and chiral phase-diagram and compare the results with recent lattice calculations. We find that PLSM chiral boundary is located in upper band of the lattice QCD calculations and agree well with the freeze-out results deduced from various high-energy experiments and thermal models. Also, we find that the chiral temperature calculated from HRG is larger than that from PLSM. This is also larger than the freeze-out temperatures calculated in lattice QCD and deduced from experiments and thermal models. The corresponding temperature and chemical potential are very similar to that of PLSM. Although the results from PNJL and QLSM keep the same behavior, their chiral temperature is higher than that of PLSM and HRG. This might be interpreted due the very heavy quark masses implemented in both models.
Critical Behavior at the Chiral Phase Transition
Bernard, C W; DeTar, C E; Gottlieb, S; Heller, U M; Hetrick, J E; Jegerlehner, B; Rummukainen, K; Sugar, R L; Toussaint, D; Wingate, M; Jegerlehner, Beat
1998-01-01
Quantum chromodynamics with two zero mass flavors is expected to exhibit a phase transition with O(4) critical behavior. Fixing the universality class is important for phenomenology and for facilitating the extrapolation of simulation data to physical quark mass values. At Lattice '96 the Tsukuba and Bielefeld groups reported results from new simulations with dynamical staggered quarks at $N_t = 4$, which suggested a departure from the expected critical behavior. We report observations of similar deviations and discuss efforts in progress to understand this phenomenon.
On the chiral phase transition in the linear sigma model
International Nuclear Information System (INIS)
The Cornwall- Jackiw-Tomboulis (CJT) effective action for composite operators at finite temperature is used to investigate the chiral phase transition within the framework of the linear sigma model as the low-energy effective model of quantum chromodynamics (QCD). A new renormalization prescription for the CJT effective action in the Hartree-Fock (HF) approximation is proposed. A numerical study, which incorporates both thermal and quantum effect, shows that in this approximation the phase transition is of first order. However, taking into account the higher-loop diagrams contribution the order of phase transition is unchanged. (author)
Chiral Phase Transition at Finite Isospin Density in Linear Sigma Model
Institute of Scientific and Technical Information of China (English)
SHU Song; LI Jia-Rong
2005-01-01
Using the linear sigma model, we have introduced the pion isospin chemical potential. The chiral phase transition is studied at finite temperatures and finite isospin densities. We have studied the μ - T phase diagram for the chiral phase transition and found the transition cannot happen below a certain low temperature because of the BoseEinstein condensation in this system. Above that temperature, the chiral phase transition is studied by the isotherms of pressure versus density. We indicate that the transition, in the chiral limit, is a first-order transition from a low-density phase to a high-density phase like a gas-liquid phase transition.
Chiral and deconfining phase transitions from holographic QCD study
Fang, Zhen; He, Song; Li, Danning
2016-06-01
A preliminary quantitative study to match the lattice QCD simulation on the chiral and deconfining phase transitions of QCD in the bottom-up holographic framework is given. We constrain the relation between dilaton field ϕ and metric warp factor Ae and get several reasonable models in the Einstein-Dilaton system. Using the potential reconstruction approach, we solve the corresponding gravity background. Then we fit the background-related parameters by comparing the equation of state with the two-flavor lattice QCD results. After that we study the temperature dependent behavior of Polyakov loop and chiral condensate under those background solutions. We find that the results are in good agreement with the two-flavor lattice results. All the studies about the equation of state, the Polyakov loop and the chiral condensate signal crossover behavior of the phase transitions, which are consistent with the current understanding on the QCD phase transitions with physical quark mass. Furthermore, the extracted transition temperatures are comparable with the two-flavor lattice QCD results.
Meson loop effect on high density chiral phase transition
Sakaguchi, T; Kouno, H; Yahiro, M; Sakaguchi, Tomohiko; Matsuzaki, Masayuki; Kouno, Hiroaki; Yahiro, Masanobu
2006-01-01
We test the stability of the mean-field solution in the Nambu--Jona-Lasinio model. For stable solutions with respect to both the \\sigma and \\pi directions, we investigate effects of the mesonic loop corrections of 1/N_c, which correspond to the next-to-leading order in the 1/N_c expansion, on the high density chiral phase transition. The corrections weaken the first order phase transition and shift the critical chemical potential to a lower value. At N_c=3, however, instability of the mean field effective potential prevents us from determining the minimum of the corrected one.
Net baryon number probability distribution near the chiral phase transition
Morita, Kenji; Skokov, Vladimir; Friman, Bengt; Redlich, Krzysztof
2014-01-01
We discuss the properties of the net baryon number probability distribution near the chiral phase transition to explore the effect of critical fluctuations. Our studies are performed within Landau theory, where the coefficients of the polynomial potential are parametrized, so as to reproduce the mean-field (MF), the Z(2) , and the O(4) scaling behaviors of the cumulants of the net baryon number. We show that in the critical region the structure of the probability distribution changes, dependi...
Non-equilibrium physics at a holographic chiral phase transition
International Nuclear Information System (INIS)
The D3/D7 system holographically describes an N=2 gauge theory which spontaneously breaks a chiral symmetry by the formation of a quark condensate in the presence of a magnetic field. At finite temperature it displays a first order phase transition. We study out of equilibrium dynamics associated with this transition by placing probe D7 branes in a geometry describing a boost-invariant expanding or contracting plasma. We use an adiabatic approximation to track the evolution of the quark condensate in a heated system and reproduce the phase structure expected from equilibrium dynamics. We then study solutions of the full partial differential equation that describes the evolution of out of equilibrium configurations to provide a complete description of the phase transition including describing aspects of bubble formation. (orig.)
QCD phase transition with chiral quarks and physical quark masses.
Bhattacharya, Tanmoy; Buchoff, Michael I; Christ, Norman H; Ding, H-T; Gupta, Rajan; Jung, Chulwoo; Karsch, F; Lin, Zhongjie; Mawhinney, R D; McGlynn, Greg; Mukherjee, Swagato; Murphy, David; Petreczky, P; Renfrew, Dwight; Schroeder, Chris; Soltz, R A; Vranas, P M; Yin, Hantao
2014-08-22
We report on the first lattice calculation of the QCD phase transition using chiral fermions with physical quark masses. This calculation uses 2+1 quark flavors, spatial volumes between (4 fm)(3) and (11 fm)(3) and temperatures between 139 and 196 MeV. Each temperature is calculated at a single lattice spacing corresponding to a temporal Euclidean extent of N(t) = 8. The disconnected chiral susceptibility, χ(disc) shows a pronounced peak whose position and height depend sensitively on the quark mass. We find no metastability near the peak and a peak height which does not change when a 5 fm spatial extent is increased to 10 fm. Each result is strong evidence that the QCD "phase transition" is not first order but a continuous crossover for m(π) = 135 MeV. The peak location determines a pseudocritical temperature T(c) = 155(1)(8) MeV, in agreement with earlier staggered fermion results. However, the peak height is 50% greater than that suggested by previous staggered results. Chiral SU(2)(L) × SU(2)(R) symmetry is fully restored above 164 MeV, but anomalous U(1)(A) symmetry breaking is nonzero above T(c) and vanishes as T is increased to 196 MeV.
The QCD phase transition with physical-mass, chiral quarks
Bhattacharya, Tanmoy; Christ, Norman H; Ding, H -T; Gupta, Rajan; Jung, Chulwoo; Karsch, F; Lin, Zhongjie; Mawhinney, R D; McGlynn, Greg; Mukherjee, Swagato; Murphy, David; Petreczky, P; Schroeder, Chris; Soltz, R A; Vranas, P M; Yin, Hantao
2014-01-01
We report on the first lattice calculation of the QCD phase transition using chiral fermions at physical values of the quark masses. This calculation uses 2+1 quark flavors, spatial volumes between (4 fm$)^3$ and (11 fm$)^3$ and temperatures between 139 and 196 MeV . Each temperature was calculated using a single lattice spacing corresponding to a temporal Euclidean extent of $N_t=8$. The disconnected chiral susceptibility, $\\chi_{\\rm disc}$ shows a pronounced peak whose position and height depend sensitively on the quark mass. We find no metastability in the region of the peak and a peak height which does not change when a 5 fm spatial extent is increased to 10 fm. Each result is strong evidence that the QCD ``phase transition'' is not first order but a continuous cross-over for $m_\\pi=135$ MeV. The peak location determines a pseudo-critical temperature $T_c = 155(1)(8)$ MeV. Chiral $SU(2)_L\\times SU(2)_R$ symmetry is fully restored above 164 MeV, but anomalous $U(1)_A$ symmetry breaking is non-zero above $T...
Topological String in Quantum-Chromodynamical Chiral Phase Transitions
Institute of Scientific and Technical Information of China (English)
LI Yun-De
2005-01-01
@@ It is pointed out that if in heavy ion collision processes, the quark-gluon plasma SU(2) chiral phase transition really takes place and the phase transition is a second order. Then the topological string, i.e., the π string, will be formed. The main effect of this phenomenon is that there will be a number of pions produced by decay of the π string in the final state. The pions from the decay of the π string lead to the same effect of decreasing the Hanbury-Brown-Twiss peak in two-pion spectra which is just as that of the long-lived hadronic resonances.At relativistic heavy-ion collision and large hadron collision energies, it is expected that the factors are about α～ 0.7 - 0.9 and α～ 0.6 - 0.85, respectively.
Meson phenomenology and phase transitions in nonlocal chiral quark models
Carlomagno, J. P.; Gomez Dumm, D.; Pagura, V.; Scoccola, N. N.
2015-07-01
We study the features of nonlocal chiral quark models that include wave function renormalization. Model parameters are determined from meson phenomenology, considering different nonlocal form factor shapes. In this context we analyze the characteristics of the deconfinement and chiral restoration transitions at finite temperature and chemical potential, introducing the couplings of fermions to the Polyakov loop for different Polyakov potentials. The results for various thermodynamical quantities are compared with data obtained from lattice QCD calculations.
Yu, Lang; Huang, Mei
2015-01-01
We study the chiral phase transition in the presence of the chiral chemical potential $\\mu_5$ using the two-flavor Nambu--Jona-Lasinio model. In particular, we analyze the reason why one can obtain two opposite behaviors of the chiral critical temperature as a function of $\\mu_5$ in the framework of different regularization schemes. We compare the modifications of the chiral condensate and the critical temperature due to $\\mu_5$ in different regularization schemes, analytically and numerically. Finally, we find that, for the conventional hard-cutoff regularization scheme, the increasing dependence of the critical temperature on the chiral chemical potential is an artifact, which is caused by the fact that it does not include complete contribution from the thermal fluctuations. When the thermal contribution is fully taken into account, the chiral critical temperature should decrease with $\\mu_5$.
Recent progress in understanding deconfinement and chiral restoration phase transitions
Shuryak, Edward
2016-01-01
Paradigme shift in gauge topology, from instantons to their constituents -- instanton-dyons -- has recently lead to very significant advances. Like instantons, they have fermionic zero modes, and their collectivization at sufficiently high density explains the chiral symmetry breaking. Unlike instantons, these objects have electric and magnetic charges. Their back reaction on the mean value of the Polyakov line (holonomy) allows to explain the deconfinement transition. The talk summarizes recent works on the dyon ensemble, done in the mean field approximation (MFA), and also by direct numerical statistical simulation. Introduction of non-trivial quark periodicity conditions leads to drastic changes in both deconfinement and chiral transitions. In particulaly, in the so called Z(N_c)-QCD model the former gets much stronger, while the latter does not seem to occur at all.
Probing the chiral phase transition of Nf=2 clover fermions with valence overlap fermions
International Nuclear Information System (INIS)
Overlap fermions are a powerful tool for investigating the chiral and topological structure of the vacuum and the thermal states of QCD. We study various chiral and topological aspects of the finite temperature phase transition of Nf=2 flavours of O(a) improved Wilson fermions, using valence overlap fermions as a probe. Particular emphasis is placed upon the analysis of the spectral density and the localisation properties of the eigenmodes as well as on the local structure of topological charge fluctuations in the vicinity of the chiral phase transition. The calculations are done on 163 x 8 lattices generated by the DIK collaboration. (orig.)
Chiral and deconfinement phase transition in the Hamiltonian approach to QCD in Coulomb gauge
Reinhardt, H
2016-01-01
The chiral and deconfinement phase transitions are investigated within the variational Hamiltonian approach to QCD in Coulomb gauge. The temperature $\\beta^{-1}$ is introduced by compactifying a spatial dimension. Thereby the whole temperature dependence is encoded in the vacuum state on the spatial manifold $\\mathbb{R}^2 \\times S^1(\\beta)$. The chiral quark condensate and the dual quark condensate (dressed Polyakov loop) are calculated as function of the temperature. From their inflection points the pseudo-critical temperatures for the chiral and deconfinement crossover transitions are determined. Using the zero-temperature quark and gluon propagators obtained within the variational approach as input, we find 226 MeV and 262 MeV, respectively, for the chiral and deconfinement transition.
UA(1) breaking and phase transition in chiral random matrix model
Sano, T; Ohtani, M
2009-01-01
We propose a chiral random matrix model which properly incorporates the flavor-number dependence of the phase transition owing to the \\UA(1) anomaly term. At finite temperature, the model shows the second-order phase transition with mean-field critical exponents for two massless flavors, while in the case of three massless flavors the transition turns out to be of the first order. The topological susceptibility satisfies the anomalous \\UA(1) Ward identity and decreases gradually with the temperature increased.
Effects of gauge boson mass on chiral and deconfinement phase transitions in QED$_{3}$
Yin, Pei-Lin; Feng, Hong-Tao; Zong, Hong-Shi
2016-01-01
Based on the experimental observation that there is a coexisting region between the antiferromagnetic (AF) and $\\textit{d}$-wave superconducting ($\\textit{d}$SC) phases, the influences of gauge boson mass $m_{a}$ on chiral symmetry restoration and deconfinement phase transitions in QED$_{3}$ are investigated simultaneously within a unified framework, i.e., Dyson-Schwinger equations. The results show that the chiral symmetry restoration phase transition in the presence of the gauge boson mass $m_{a}$ is a typical second-order phase transition; the chiral symmetry restoration and deconfinement phase transitions are coincident; the critical number of fermion flavors $N^{c}_{f}$ decreases as the gauge boson mass $m_{a}$ increases and there exists a boundary that separates the $N^{c}_{f}$-$m_{a}$ plane into chiral symmetry breaking/confinement region for ($N_{f}^{c}$, $m_{a}$) below the boundary and chiral symmetry restoration/deconfinement region for ($N_{f}^{c}$, $m_{a}$) above it.
Amplification of Quantum Meson Modes in the Late Time of the Chiral Phase Transition
Watanabe, K
2007-01-01
We investigate the time evolution of the quantum meson modes in the late time of chiral phase transition. In particular, it is shown that there exists a possible solution to the equation of motion for the quantum meson modes, which reveals a parametric resonance and/or resonance through forced oscillation induced by the small oscillation of the chiral condensate. After that, we demonstrate the unstable regions for the quantum meson modes in both the cases of a uniform and spatially expanding system.
The chicken or the egg; or Who ordered the chiral phase transition?
Kogan, I I; Tekin, B; Kogan, Ian I.; Kovner, Alex; Tekin, Bayram
2001-01-01
We draw an analogy between the deconfining transition in the 2+1 dimensional Georgi-Glashow model and the chiral phase transition in 3+1 dimensional QCD. Based on the detailed analysis of the former (hep-th/0010201) we suggest that the chiral symmetry restoration in QCD at high temperature is driven by the thermal ensemble of baryons and antibaryons. The chiral symmetry is restored when roughly half of the volume is occupied by the baryons. Surprisingly enough, even though baryons are rather heavy, a crude estimate for the critical temperature gives $T_c=180$ Mev. In this scenario the binding of the instantons is not the cause but rather a consequence of the chiral symmetry restoration.
Chiral Phase Transition and Meson Melting from AdS/QCD
Bartz, Sean P
2016-01-01
We investigate the in-medium behavior of mesons at finite temperature and baryon chemical potential within a soft-wall model of AdS/QCD. We use a quartic scalar potential to obtain the correct form of chiral symmetry breaking. At zero quark mass the chiral phase transition is second-order, becoming a crossover at physical quark mass. At zero baryon chemical potential, we find a chiral transition temperature of 155 MeV in the chiral limit and a pseudo-transition temperature of 151 MeV at physical quark mass, consistent with lattice results. In the low-temperature limit, the second-order transition occurs at a baryon chemical potential of 566 MeV while the rapid crossover occurs at 559 MeV. A new parameterization of the dilaton profile results in improved meson spectra. Meson melting occurs at a lower temperature and chemical potential than the chiral phase transition, so the vector-axial vector mass splitting remains constant until the bound states melt.
The $N_f= 2$ chiral phase transition from imaginary chemical potential with Wilson Fermions
Philipsen, Owe
2015-01-01
The order of the thermal transition in the chiral limit of QCD with two dynamical flavours of quarks is a long-standing issue. Still, it is not definitely known whether the transition is of first or second order in the continuum limit. Which of the two scenarios is realized has important implications for the QCD phase diagram and the existence of a critical endpoint at finite densities. Settling this issue by simulating at successively decreased pion mass was not conclusive yet. Recently, an alternative approach was proposed, extrapolating the first order phase transition found at imaginary chemical potential to zero chemical potential with known exponents, which are induced by the Roberge-Weiss symmetry. For staggered fermions on $N_t=4$ lattices, this results in a first order transition in the chiral limit. Here we report of $N_t=4$ simulations with Wilson fermions, where the first order region is found to be large.
The Chirality Of Life: From Phase Transitions To Astrobiology
Gleiser, Marcelo
2008-01-01
The search for life elsewhere in the universe is a pivotal question in modern science. However, to address whether life is common in the universe we must first understand the likelihood of abiogenesis by studying the origin of life on Earth. A key missing piece is the origin of biomolecular homochirality: permeating almost every life-form on Earth is the presence of exclusively levorotary amino acids and dextrorotary sugars. In this work we discuss recent results suggesting that life's homochirality resulted from sequential chiral symmetry breaking triggered by environmental events in a mechanism referred to as punctuated chirality. Applying these arguments to other potentially life-bearing platforms has significant implications for the search for extraterrestrial life: we predict that a statistically representative sampling of extraterrestrial stereochemistry will be racemic on average.
Exploring the nature of chiral phase transition in two-flavor QCD using extra heavy quarks
Ejiri, Shinji; Yamada, Norikazu
2015-01-01
Chiral phase transition of two flavor QCD at finite quark masses is known to be crossover except near the chiral limit, but it can turn to a first order transition when adding many extra flavors. This property is used to explore the nature of the phase transition of massless two flavor QCD using lattice numerical simulations. The extra heavy flavors being incorporated in the form of the hopping parameter expansion through the reweighting, the number of the extra flavors and their masses appear only in a single parameter, defined by $h$. We determine the critical value of the parameter, at which the first order and the crossover regions are separated, and examine its dependence on the two flavor mass. The lattice calculations are carried out at $N_t$=4, and show that the critical value does not depend on the two flavor mass in the range we have studied ($0.46 \\le m_\\pi/m_\\rho \\le 0.66$) and appears to remain finite and positive in the chiral limit, suggesting that the phase transition of massless two flavor QC...
Chiral phase transition and Schwinger mechanism in a pure electric field
Cao, Gaoqing
2016-01-01
We systematically study the chiral symmetry breaking and restoration in the presence of a pure electric field in the Nambu--Jona-Lasinio (NJL) model at finite temperature and baryon chemical potential. In addition, we also study the effect of the chiral phase transition on the charged pair production due to the Schwinger mechanism. For these purposes, a general formalism for parallel electric and magnetic fields is developed at finite temperature and chemical potential for the first time. In the pure electric field limit $B\\rightarrow0$, we compute the order parameter, the transverse-to-longitudinal ratio of the Goldstone mode velocities, and the Schwinger pair production rate as functions of the electric field. The inverse catalysis effect of the electric field to chiral symmetry breaking is recovered. And the Goldstone mode is find to disperse anisotropically such that the transverse velocity is always smaller than the longitudinal one, especially at nonzero temperature and baryon chemical potential. As exp...
Chiral phase transition in a lattice fermion-gauge-scalar model with U(1) gauge symmetry
International Nuclear Information System (INIS)
The chiral phase transition induced by a charged scalar field is investigated numerically in a lattice fermion-gauge-scalar model with U(1) gauge symmetry, proposed recently as a model for dynamical fermion mass generation. For very strong gauge coupling the transition is of second order and its scaling properties are very similar to those of the Nambu-Jona-Lasinio model. However, in the vicinity of the tricritical point at somewhat weaker coupling, where the transition changes the order, the scaling behavior is different. Therefore it is worthwhile to investigate the continuum limit of the model at this point. (orig.)
Nf=2 QCD chiral phase transition with Wilson fermions at zero and imaginary chemical potential
Philipsen, Owe; Pinke, Christopher
2016-06-01
The order of the thermal phase transition in the chiral limit of quantum chromodynamics (QCD) with two dynamical flavors of quarks is a long-standing issue and still not known in the continuum limit. Whether the transition is first or second order has important implications for the QCD phase diagram and the existence of a critical end point at finite densities. We follow a recently proposed approach to explicitly determine the region of first order chiral transitions at imaginary chemical potential, where it is large enough to be simulated, and extrapolate it to zero chemical potential with known critical exponents. Using unimproved Wilson fermions on coarse Nt=4 lattices, the first order region turns out to be so large that no extrapolation is necessary. The critical pion mass mπc≈560 MeV is by nearly a factor 10 larger than the corresponding one using staggered fermions. Our results are in line with investigations of three-flavor QCD using improved Wilson fermions and indicate that the systematic error on the two-flavor chiral transition is still of order 100%.
Pulse and quench induced dynamical phase transition in a chiral multiferroic spin chain
Azimi, M.; Sekania, M.; Mishra, S. K.; Chotorlishvili, L.; Toklikishvili, Z.; Berakdar, J.
2016-08-01
Quantum dynamics of magnetic order in a chiral multiferroic chain is studied. We consider two different scenarios: ultrashort terahertz excitations or a sudden electric field quench. Performing analytical and numerical exact diagonalization calculations, we trace the pulse induced spin dynamics and extract quantities that are relevant to quantum information processing. In particular, we analyze the dynamics of the system chirality, the von Neumann entropy, and the pairwise and many-body entanglement. If the characteristic frequencies of the generated states are noncommensurate, then a partial loss of pair concurrence occurs. Increasing the system size, this effect becomes even more pronounced. Many-particle entanglement and chirality are robust and persist in the incommensurate phase. To analyze the dynamical quantum transitions for the quenched and pulsed dynamics we combined the Weierstrass factorization technique for entire functions and the Lanczos exact diagonalization method. For a small system we obtained analytical results including the rate function of the Loschmidt echo. Exact numerical calculations for a system up to 40 spins confirm phase transition. Quench-induced dynamical transitions have been extensively studied recently. Here we show that related dynamical transitions can be achieved and controlled by appropriate electric field pulses.
A large N phase transition in the continuum two dimensional SU(N) X SU(N) principal chiral model
R. Narayanan; Neuberger, H.; Vicari, E.
2008-01-01
It is established by numerical means that the continuum large N principal chiral model in two dimensions has a phase transition in a smoothed two point function at a critical distance of the order of the correlation length.
Chiral Phase Transition in the Soft-Wall Model of AdS/QCD
Chelabi, Kaddour; Huang, Mei; Li, Danning; Wu, Yue-Liang
2015-01-01
We investigate the chiral phase transition in the soft-wall model of AdS/QCD at zero chemical potential for two-flavor and three-flavor cases, respectively. We show that there is no spontaneous chiral symmetry breaking in the original soft-wall model. After detailed analysis, we find that in order to realize chiral symmetry breaking and restoration, both profiles for the scalar potential and the dilaton field are essential. The scalar potential determines the possible solution structure of the chiral condensate, except the mass term, it takes another quartic term for the two-flavor case, and for the three-flavor case, one has to take into account an extra cubic term due to the t'Hooft determinant interaction. The profile of the dilaton field reflects the gluodynamics, which is negative at a certain ultraviolet scale and approaches positive quadratic behavior at far infrared region. With this set-up, the spontaneous chiral symmetry breaking in the vacuum and its restoration at finite temperature can be realize...
Many flavor approach to study the nature of chiral phase transition of two-flavor QCD
Yamada, Norikazu; Iwami, Ryo
2016-01-01
We perform lattice numerical simulations to study the phase transition of QCD at finite temperature to clarify the nature of the transition of massless two flavor QCD. We investigate QCD with two light and Nf heavy quarks instead of two-flavor QCD, and focus on the light quark mass dependence of the critical heavy mass, below which the transition is of first order. The heavy quarks are incorporated into two flavor configurations in the form of the hopping parameter expansion through the reweighting technique. The nature of the transition is identified by the shape of the constraint effective potential at the critical temperature. Our result indicates that the critical heavy mass remains finite in the chiral limit of the two flavors, suggesting the phase transition of massless two-flavor QCD is of second order.
The chiral phase transition in QCD critical phenomena and long wavelength pion oscillations
Rajagopal, K
1995-01-01
In QCD with two massless quarks, the chiral phase transition is plausibly in the same universality class as the classical O(4) magnet. To test this hypothesis, critical exponents characterizing the behaviour of universal quantities near the 2nd order critical point can be calculated and compared to results from lattice simulations. Present simulations already allow many qualitative tests; quantitative tests await future simulations with longer correlation lengths. In a heavy ion collision, a long correlation length would lead to large fluctuations in the number ratio of neutral to charged pions. Unfortunately, no equilibrium correlation length gets long enough for this to occur. Modelling the dynamics of the chiral order parameter in a far from equilibrium transition by quenching in the linear sigma model suggests that long wavelength modes of the pion field can be amplified. This could have dramatic phenomenological consequences. Theoretical advances include attempts to relax the quench approximation and to ...
Floquet topological phase transitions and chiral edge states in a kagome lattice
Energy Technology Data Exchange (ETDEWEB)
He, Chaocheng; Zhang, Zhiyong, E-mail: zyzhang@nju.edu.cn
2014-09-05
The Floquet topological phases and chiral edge states in a kagome lattice under a circularly-polarized driving field are studied. In the off-resonant case, the system exhibits the similar character as the kagome lattice model with staggered magnetic fluxes, but the total band width is damped in oscillation. In the on-resonant case, the degeneracy splitting at the Γ point does not always result in a gap. The positions of the other two gaps are influenced by the flat band. With the field intensity increased, these two gaps undergo closing-then-reopening processes, accompanied with the changing of the winding numbers. - Highlights: • A kagome lattice under a circularly-polarized driving field is studied. • The band structures and chiral edge states are studied via exact Floquet method. • Various modifications of the Floquet band structure are found. • Floquet topological phase transitions appear in both off- and on-resonant cases.
Chiral phase transition scenarios from the vector meson extended Polyakov quark meson model
Kovács, Péter
2015-01-01
Chiral phase transition is investigated in an $SU(3)_L \\times SU(3)_R$ symmetric vector meson extended linear sigma model with additional constituent quarks and Polyakov loops (extended Polyakov quark meson model). The parameterization of the Lagrangian is done at zero temperature in a hybrid approach, where the mesons are treated at tree-level, while the constituent quarks at 1-loop level. The temperature and baryochemical potential dependence of the two assumed scalar condensates are calculated from the hybrid 1-loop level equations of states. The order of the phase transition along the $T=0$ and $\\mu_B=0$ axes are determined for various parameterization scenarios. We find that in order to have a first order phase transition at $T=0$ as a function of $\\mu_B$ a light isoscalar particle is needed.
Influence of the Polyakov loop on the chiral phase transition in the two flavor chiral quark model
Markó, G.; Szép, Zs.
2010-09-01
The SU(2)L×SU(2)R chiral quark model consisting of the (σ,π→) meson multiplet and the constituent quarks propagating on the homogeneous background of a temporal gauge field is solved at finite temperature and quark baryon chemical potential μq using an expansion in the number of flavors Nf, both in the chiral limit and for the physical value of the pion mass. Keeping the fermion propagator at its tree level, several approximations to the pion propagator are investigated. These approximations correspond to different partial resummations of the perturbative series. Comparing their solution with a diagrammatically formulated resummation relying on a strict large-Nf expansion of the perturbative series, one concludes that only when the local part of the approximated pion propagator resums infinitely many orders in 1/Nf of fermionic contributions a sufficiently rapid crossover transition at μq=0 is achieved allowing for the existence of a tricritical point or a critical end point in the μq-T phase diagram. The renormalization and the possibility of determining the counterterms in the resummation provided by a strict large-Nf expansion are investigated.
Progress in vacuum susceptibilities and their applications to the chiral phase transition of QCD
International Nuclear Information System (INIS)
The QCD vacuum condensates and various vacuum susceptibilities are all important parameters which characterize the nonperturbative properties of the QCD vacuum. In the QCD sum rules external field formula, various QCD vacuum susceptibilities play important roles in determining the properties of hadrons. In this paper, we review the recent progress in studies of vacuum susceptibilities together with their applications to the chiral phase transition of QCD. The results of the tensor, the vector, the axial–vector, the scalar, and the pseudo-scalar vacuum susceptibilities are shown in detail in the framework of Dyson–Schwinger equations
Progress in vacuum susceptibilities and their applications to the chiral phase transition of QCD
Cui, Zhu-Fang; Shi, Yuan-Mei; Wang, Yong-Long; Zong, Hong-Shi
2015-01-01
The QCD vacuum condensates and various vacuum susceptibilities are all important parameters which characterize the nonperturbative properties of the QCD vacuum. In the QCD sum rules external field formula, various QCD vacuum susceptibilities play important roles in determining the properties of hadrons. In this paper, we review the recent progress in studies of vacuum susceptibilities together with their applications to the chiral phase transition of QCD. The results of the tensor, the vector, the axial-vector, the scalar, and the pseudo-scalar vacuum susceptibilities are shown in detail in the framework of Dyson-Schwinger equations.
Chiral phase transition in an extended linear sigma model: initial results
Wolf, Gy; Szép, Zs
2014-01-01
We investigate the scalar meson mass dependence on the chiral phase transition in the framework of an SU(3), (axial)vector meson extended linear sigma model with additional constituent quarks and Polyakov loops. We determine the parameters of the Lagrangian at zero temperature in a hybrid approach, where we treat the mesons at tree-level, while the constituent quarks at 1-loop level. We assume two nonzero scalar condensates and together with the Polyakov-loop variables we determine their temperature dependence according to the 1-loop level field equations.
Effects of (axialvector mesons on the chiral phase transition: initial results
Directory of Open Access Journals (Sweden)
Kovács P.
2014-01-01
Full Text Available We investigate the effects of (axialvector mesons on the chiral phase transition in the framework of an SU(3, (axialvector meson extended linear sigma model with additional constituent quarks and Polyakov loops. We determine the parameters of the Lagrangian at zero temperature in a hybrid approach, where we treat the mesons at tree-level, while the constituent quarks at 1-loop level. We assume two nonzero scalar condensates and together with the Polyakov-loop variables we determine their temperature dependence according to the 1-loop level field equations.
Chiral phase transition at finite temperature and conformal dynamics in large Nf QCD
Miura, Kohtaroh
2011-01-01
We investigate the chiral phase transition at finite temperature (T) in colour SU(Nc=3) Quantum Chromodynamics (QCD) with six species of fermions (Nf=6) in the fundamental representation by using lattice QCD with improved staggered fermions. By considering lattices with several temporal extensions Nt, we observe asymptotic scaling for Nt > 4. We then extract the dimensionless ratio Tc/Lambda_L (Lambda_L = Lattice Lambda-parameter) for Nf = 6 and Nf = 8, the latter relying on our earlier results. Further, we collect the critical couplings beta^c for the chiral phase transition at Nf = 0 (quenched), and Nf = 4 at a fixed Nt = 6. The results are consistent with enhanced fermionic screening at larger Nf. The Tc/Lambda_L depends very mildly on Nf in the Nf = 0 - 4 region, starts increasing at Nf = 6, and becomes significantly larger at Nf = 8, close to the edge of the conformal window. We discuss interpretations of these results as well as their possible interrelation with preconformal dynamics in the light of a f...
Fluctuations and the Phase Transition in a Chiral Model with Polyakov Loops
Sasaki, C.; Friman, B.; Redlich, K.
2007-01-01
We explore the NJL model with Polyakov loops for a system of three colors and two flavors within the mean-field approximation, where both chiral symmetry and confinement are taken into account. We focus on the phase structure of the model and study the chiral and Polyakov loop susceptibilities.
Chiral phase transition in the vector meson extended linear sigma model
Kovács, Péter; Wolf, György
2015-01-01
In the framework of an SU(3) (axial)vector meson extended linear sigma model with additional constituent quarks and Polyakov loops, we investigate the effects of (axial)vector mesons on the chiral phase transition. The parameters of the Lagrangian are set at zero temperature and we use a hybrid approach where in the effective potential the constituent quarks are treated at one-loop level and all the mesons at tree-level. We have four order parameters, two scalar condensates and two Polyakov loop variables and their temperature and baryochemical potential dependence are determined from the corresponding field equations. We also investigate the changes of the tree-level scalar meson masses in the hot and dense medium.
Ichihara, Terukazu; Ohnishi, Akira
2015-01-01
We investigate the net-baryon number fluctuations across the chiral phase transition at finite density in the strong coupling and chiral limit. Mesonic field fluctuations are taken into account by using the auxiliary field Monte-Carlo method. We find that the higher-order cumulant ratios, $S\\sigma$ and $\\kappa\\sigma^2$, show oscillatory behavior around the phase boundary at $\\mu/T\\gtrsim 0.2$, and there exists the region where the higher-order cumulant ratios are negative. The negative region of $\\kappa\\sigma^2$ is found to shrink with increasing lattice size. This behavior agrees with the expectations from the scaling analysis.
Global Currents, Phase Transitions, and Chiral Symmetry Breaking in Large N_c Gauge Theory
Albash, T; Johnson, C V; Kundu, A; Albash, Tameem; Filev, Veselin; Johnson, Clifford V.; Kundu, Arnab
2006-01-01
We study the finite temperature dynamics of SU(N_c) gauge theory for large N_c, with fundamental quark flavours in a quenched approximation, in the presence of a fixed charge under a global current. We observe several notable phenomena. There is a first order phase transition where the quark condensate jumps discontinuously at finite quark mass, generalizing similar transitions seen at zero charge. We find a non-zero condensate at zero quark mass above a critical value of the charge, corresponding to an analogue of spontaneous chiral symmetry breaking at finite number density. We find that the spectrum of mesons contains the expected associated Goldstone (``pion'') degrees of freedom with a mass dependence on the quark mass that is consistent with the Gell-Mann-Oakes-Renner relation. Our tool in these studies is holography, the string dual of the gauge theory being the geometry of $N_c$ spinning D3-branes at finite temperature, probed by a D7-brane.
Chiral phase transitions in the linear sigma model in the Tsallis nonextensive statistics
Ishihara, Masamichi
2016-01-01
We studied chiral phase transitions in the Tsallis nonextensive statistics which has two parameters, the temperature $T$ and entropic parameter $q$. The linear sigma model was used in this study. The critical temperature, condensate, masses, and energy density were calculated under the massless free particle approximation. The critical temperature decreases as $q$ increases. The condensate at $q>1$ is smaller than that at $q=1$. The sigma mass at $q>1$ is heavier than the mass at $q=1$ at high temperature, while the sigma mass at $q>1$ is lighter than the mass at $q=1$ at low temperature. The pion mass at $q>1$ is heavier than the mass at $q=1$. The energy density increases remarkably as $q$ increases. The $q$ dependence in the case of the $q$-expectation value is weaker than that in the case of the conventional expectation value with a Tsallis distribution. The parameter $q$ should be smaller than $4/3$ from energetic point of view. The validity of the Tsallis statistics can be determined by the difference i...
The effect of the Polyakov loop on the chiral phase transition
Directory of Open Access Journals (Sweden)
Szép Zs.
2011-04-01
Full Text Available The Polyakov loop is included in the S U(2L × S U(2R chiral quark-meson model by considering the propagation of the constituent quarks, coupled to the (σ, π meson multiplet, on the homogeneous background of a temporal gauge field, diagonal in color space. The model is solved at finite temperature and quark baryon chemical potential both in the chiral limit and for the physical value of the pion mass by using an expansion in the number of flavors Nf. Keeping the fermion propagator at its tree-level, a resummation on the pion propagator is constructed which resums infinitely many orders in 1/Nf, where O(1/Nf represents the order at which the fermions start to contribute in the pion propagator. The influence of the Polyakov loop on the tricritical or the critical point in the µq – T phase diagram is studied for various forms of the Polyakov loop potential.
The effect of the Polyakov loop on the chiral phase transition
Markó, G.; Szép, Zs.
2011-04-01
The Polyakov loop is included in the S U(2)L × S U(2)R chiral quark-meson model by considering the propagation of the constituent quarks, coupled to the (σ, π) meson multiplet, on the homogeneous background of a temporal gauge field, diagonal in color space. The model is solved at finite temperature and quark baryon chemical potential both in the chiral limit and for the physical value of the pion mass by using an expansion in the number of flavors Nf. Keeping the fermion propagator at its tree-level, a resummation on the pion propagator is constructed which resums infinitely many orders in 1/Nf, where O(1/Nf) represents the order at which the fermions start to contribute in the pion propagator. The influence of the Polyakov loop on the tricritical or the critical point in the µq - T phase diagram is studied for various forms of the Polyakov loop potential.
Ruggieri, M.; Peng, G. X.
2016-05-01
In this article, we study spontaneous chiral symmetry breaking for quark matter in the background of static and homogeneous parallel electric field E and magnetic field B . We use a Nambu-Jona-Lasinio model with a local kernel interaction to compute the relevant quantities to describe chiral symmetry breaking at a finite temperature for a wide range of E and B . We study the effect of this background on the inverse catalysis of chiral symmetry breaking for E and B of the same order of magnitude. We then focus on the effect of the equilibration of chiral density n5 , produced dynamically by an axial anomaly on the critical temperature. The equilibration of n5 , a consequence of chirality-flipping processes in the thermal bath, allows for the introduction of the chiral chemical potential μ5, which is computed self-consistently as a function of the temperature and field strength by coupling the number equation to the gap equation and solving the two within an expansion in E /T2 , B /T2 , and μ52/T2 . We find that even if chirality is produced and equilibrates within a relaxation time τM , it does not change drastically the thermodynamics, with particular reference to the inverse catalysis induced by the external fields, as long as the average μ5 at equilibrium is not too large.
Ruggieri, M
2016-01-01
In this article we study spontaneous chiral symmetry breaking for quark matter in the background of an electric-magnetic flux tube with static, homogeneous and parallel electric field $\\bm E$ and magnetic field $\\bm B$. We use a Nambu-Jona-Lasinio model with a local kernel interaction to compute the relevant quantities to describe chiral symmetry breaking at finite temperature for a wide range of $E$ and $B$. We study the effect of the flux tube background on inverse catalysis of chiral symmetry breaking for $E$ and $B$ of the same order of magnitude. We then focus on the effect of equilibration of chiral density, $n_5$, produced dynamically by axial anomaly on the critical temperature. The equilibration of $n_5$, a consequence of chirality flipping processes in the thermal bath, allows for the introduction of the chiral chemical potential, $\\mu_5$, which is computed self-consistently as a function of temperature and field strength by coupling the number equation to the gap equation. We find that even if chir...
Anomalous dimension, chiral phase transition and inverse magnetic catalysis in soft-wall AdS/QCD
Fang, Zhen
2016-07-01
A modified soft-wall AdS/QCD model with a z-dependent bulk scalar mass is proposed. We argue for the necessity of a modified bulk scalar mass from the quark mass anomalous dimension and carefully constrain the form of bulk mass by the corresponding UV and IR asymptotics. After fixing the form of bulk scalar mass, we calculate the mass spectra of (axial-)vector and pseudoscalar mesons, which have a good agreement with the experimental data. The behavior of chiral phase transition is also investigated, and the results are consistent with the standard scenario and lattice simulations. Finally, the issue of chiral magnetic effects is addressed. We find that the inverse magnetic catalysis emerges naturally from the modified soft-wall model, which is consistent with the recent lattice simulations.
Novel Lifshitz point for chiral transition in the magnetic field
Directory of Open Access Journals (Sweden)
Toshitaka Tatsumi
2015-04-01
Full Text Available Based on the generalized Ginzburg–Landau theory, chiral phase transition is discussed in the presence of magnetic field. Considering the chiral density wave we show that chiral anomaly gives rise to an inhomogeneous chiral phase for nonzero quark-number chemical potential. Novel Lifshitz point appears on the vanishing chemical potential line, which may be directly explored by the lattice QCD simulation.
The effect of the Polyakov loop on the chiral phase transition
Szép Zs.; Markó G.
2010-01-01
The Polyakov loop is included in the SU(2)_L x SU(2)_R chiral quark-meson model by considering the propagation of the constituent quarks, coupled to the (sigma,pi) meson multiplet, on the homogeneous background of a temporal gauge field, diagonal in color space. The model is solved at finite temperature and quark baryon chemical potential both in the chiral limit and for the physical value of the pion mass by using an expansion in the number of flavors N_f. Keeping the fermion propagator at i...
Chiral and deconfinement phase transitions in N{sub f}=2 and N{sub f}=2+1 quantum chromodynamics
Energy Technology Data Exchange (ETDEWEB)
Luecker, Jan
2013-07-15
In this thesis, we investigate the phase structure of quantum chromodynamics (QCD) in the framework of Dyson-Schwinger equations (DSEs). The aim is to study the chiral and deconfinement phase transitions at finite chemical potential. To this end, we employ and test a novel truncation scheme for the quark and gluon Dyson-Schwinger equations. We develop our truncation in three steps. To begin with, we use a quenched gluon propagator from lattice Yang-Mills theory. To account for unquenching, we then add the quark loop in the gluon DSE, firstly with bare quarks and in the final version of our truncation with fully dressed quarks. In the last step it is also possible to take into account the coupling of light and strange quarks. In effective models, fermionic fluctuations have been shown to move the critical end-point to large densities. We confirm this finding within our truncation for the unquenched gluon. However, this effect is suppressed once the full non-perturbative quark in the quark loop is taken into account. For the confinement/deconfinement transition we investigate three order parameters that are accessible from the quark and gluon propagators. These are the dressed Polyakov loop, the Polyakov-loop potential and positivity violations in the quark propagator. From both Polyakov-loop related order parameters, we find that the deconfinement transition can always be found in vicinity of the chiral transition. Especially at the critical end-point the phase transitions coincide. We also find that signals of positivity violations in the quark propagator vanish at the chiral transition for the two-flavour case. However, with 2+1 flavours, we find a region at large density where chiral symmetry is restored but positivity is violated. This requires further investigations. Finally, we improve our truncation by considering the back-reaction of pions in a model that has been developed in previous work. Within this model we find only a small impact on the phase
On the strength of the $U_A(1)$ anomaly at the chiral phase transition in $N_f=2$ QCD
Brandt, Bastian B; Meyer, Harvey B; Philipsen, Owe; Robaina, Daniel; Wittig, Hartmut
2016-01-01
We study the thermal transition of QCD with two degenerate light flavours by lattice simulations using $O(a)$-improved Wilson quarks. Temperature scans are performed at a fixed value of $N_t = (aT)^{-1}=16$, where $a$ is the lattice spacing and $T$ the temperature, at three fixed zero-temperature pion masses between 200 MeV and 540 MeV. In this range we find that the transition is consistent with a broad crossover. As a probe of the restoration of chiral symmetry, we study the static screening spectrum. We observe a degeneracy between the transverse isovector vector and axial-vector channels starting from the transition temperature. Particularly striking is the strong reduction of the splitting between isovector scalar and pseudoscalar screening masses around the chiral phase transition by at least a factor of three compared to its value at zero temperature. In fact, the splitting is consistent with zero within our uncertainties. This disfavours a chiral phase transition in the $O(4)$ universality class.
Indian Academy of Sciences (India)
Hisao Nakkagawa; Hiroshi Yokota; Koji Yoshida; Yuko Fueki
2003-05-01
Chiral phase transition in thermal QCD is studied by using the Dyson–Schwinger (DS) equation in the real time hard thermal loop approximation. Our results on the critical temperature and the critical coupling are signiﬁcantly different from those in the preceding analyses in the ladder DS equation, showing the importance of properly taking into account the essential thermal effects, namely the Landau damping and the unstable nature of thermal quasiparticles.
Chiral transition with magnetic fields
Ayala, Alejandro; Mizher, Ana Julia; Rojas, Juan Cristobal; Villavicencio, Cristian
2014-01-01
We study the nature of the chiral transition for an effective theory with spontaneous breaking of symmetry, where charged bosons and fermions are subject to the effects of a constant external magnetic field. The problem is studied in terms of the relative intensity of the magnetic field with respect to the mass and the temperature. When the former is the smallest of the scales, we present a suitable method to obtain magnetic and thermal corrections up to ring order at high temperature. By these means, we solve the problem of the instability in the boson sector for these theories, where the squared masses, taken as functions of the order parameter, can vanish and even become negative. The solution is found by considering the screening properties of the plasma, encoded in the resummation of the ring diagrams at high temperature. We also study the case where the magnetic field is the intermediate of the three scales and explore the nature of the chiral transition as we vary the field strength, the coupling const...
International Nuclear Information System (INIS)
A smart polymer stabilized liquid crystal (PSLC) thin film with temperature-controllable light transmittance was prepared based on a smectic-A (SmA)–chiral nematic (N*) phase transition, and then the effect of the composition and the preparation condition of the PSLC film on its thermo-optical (T-O) characteristics has been investigated in detail. Within the temperature range of the SmA phase, the PSLC shows a strong opaque state due to the focal conic alignment of liquid crystal (LC) molecules, while the film exhibits a transparent state result from the parallel alignment of N* phase LC molecules at a higher temperature. Importantly, the PSLC films with different temperature of phase transition and contrast ratio can be prepared by changing the composition of photo-polymerizable monomer/LC/chiral dopant. According to the competition between the polymerization of the curable monomers and the diffusion of LC molecules, the ultraviolet (UV) curing surrounding temperature and the intensity of UV irradiation play a critical role in tuning the size of the polymer network meshes, which in turn influence the contrast ratio and the switching speed of the film. Our observations are expected to pave the way for preparing smart PSLC thin films for applications in areas of smart windows, thermo-detectors and other information recording devices. (paper)
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 o
Finite-Temperature Phase Structure in the Chiral σ-ω Model with Dilatons
Institute of Scientific and Technical Information of China (English)
ZHANG Xiao-Bing ZHANG Xiao-Bing; LI Xue-Qian; NING Ping-Zhi
2000-01-01
We investigate the finite-temperature phase structure in a scaled chiral model which includes the dilaton (glueball) field. It is shown that hot nuclear matter undergoes a discontinuous transition in the mean field of scalar mesons as well as the Lee-Wick abnormal transition. The corresponding behavior of the gluon condensate during the chiral phase transition is also studied.
Chiral phases of fundamental and adjoint quarks
Energy Technology Data Exchange (ETDEWEB)
Natale, A. A. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC 09210-170, Santo André, SP (Brazil); Instituto de Física Teórica - UNESP Rua Dr. Bento T. Ferraz, 271, Bl.II - 01140-070, São Paulo, SP (Brazil)
2016-01-22
We consider a QCD chiral symmetry breaking model where the gap equation contains an effective confining propagator and a dressed gluon propagator with a dynamically generated mass. This model is able to explain the ratios between the chiral transition and deconfinement temperatures in the case of fundamental and adjoint quarks. It also predicts the recovery of the chiral symmetry for a large number of quarks (n{sub f} ≈ 11 – 13) in agreement with lattice data.
Insights on some chiral smectic phases
Indian Academy of Sciences (India)
B Pansu
2003-08-01
Combining layered positional order as smectic order and chirality can generate complex architectures since twist parallel to the layers is not allowed. This paper will review some new experimental results on different phases resulting from the competition between smectic positional order and twist orientational order. It concerns the TGBA and the NL*, that is the liquid line phase as well as the SmQ phase. Chiral effects in the isotropic phase will also be discussed.
Symmetry structure and phase transitions
Indian Academy of Sciences (India)
Ashok Goyal; Meenu Dahiya; Deepak Chandra
2003-05-01
We study chiral symmetry structure at ﬁnite density and temperature in the presence of external magnetic ﬁeld and gravity, a situation relevant in the early Universe and in the core of compact stars. We then investigate the dynamical evolution of phase transition in the expanding early Universe and possible formation of quark nuggets and their survival.
Finite-temperature chiral transition in real-world QCD?
International Nuclear Information System (INIS)
I present and discuss the first physics results of a Langevin simulation of finite-temperature QCD with a realistic current quark spectrum. Up to several caveats which will need to be addressed by future studies, our present results suggest that there is a first-order chiral restoration phase transition in real-world QCD, that it is driven by the light condensate and that it should be accompanied by a partial restoration of U(1)A symmetry. (orig.)
Institute of Scientific and Technical Information of China (English)
Zhao Shun-Cai; Liu Zheng-Dong; Zheng Jun; Li Gen
2011-01-01
This paper suggests a scheme of electromagnetic chirality-induced negative refraction utilizing magneto-electric cross coupling in a four-level atomic system. The negative refraction can be achieved with the two chirality coefficients having the same amplitude but the opposite phase, without requiring the simultaneous presence of an electric-dipole and a magnetic-dipole transition near the same transition frequency.
An Anderson-like model of the QCD chiral transition
Giordano, Matteo; Kovács, Tamás G.; Pittler, Ferenc
2016-06-01
We study the problems of chiral symmetry breaking and eigenmode localisation in finite-temperature QCD by looking at the lattice Dirac operator as a random Hamiltonian. We recast the staggered Dirac operator into an unconventional three-dimensional Anderson Hamiltonian ("Dirac-Anderson Hamiltonian") carrying internal degrees of freedom, with disorder provided by the fluctuations of the gauge links. In this framework, we identify the features relevant to chiral symmetry restoration and localisation of the low-lying Dirac eigenmodes in the ordering of the local Polyakov lines, and in the related correlation between spatial links across time slices, thus tying the two phenomena to the deconfinement transition. We then build a toy model based on QCD and on the Dirac-Anderson approach, replacing the Polyakov lines with spin variables and simplifying the dynamics of the spatial gauge links, but preserving the above-mentioned relevant dynamical features. Our toy model successfully reproduces the main features of the QCD spectrum and of the Dirac eigenmodes concerning chiral symmetry breaking and localisation, both in the ordered (deconfined) and disordered (confined) phases. Moreover, it allows us to study separately the roles played in the two phenomena by the diagonal and the off-diagonal terms of the Dirac-Anderson Hamiltonian. Our results support our expectation that chiral symmetry restoration and localisation of the low modes are closely related, and that both are triggered by the deconfinement transition.
Magnetic properties in the inhomogeneous chiral phase
Yoshiike, Ryo; Tatsumi, Toshitaka
2016-01-01
We investigate the magnetic properties of quark matter in the inhomogeneous chiral phase, where both scalar and pseudoscalar condensates spatially modulate. The energy spectrum of the lowest Landau level becomes asymmetric about zero in the external magnetic field, and gives rise to the remarkably magnetic properties: quark matter has a spontaneous magnetization, while the magnetic susceptibility does not diverge on the critical point.
Electromagnetic transitions in multiple chiral doublet bands
Jia, Hui; Wang, Shou-Yu; Wang, Shuo; Liu, Chen
2016-01-01
Multiple chiral doublet bands (M$\\chi$D) in the $80$, 130 and $190$ mass regions are studied by the model of $\\gamma$=90$^{\\circ}$ triaxial rotor coupled with identical symmetric proton-neutron configurations. By selecting the suitable basis, the calculated wave functions are explicitly exhibited to be symmetric under the operator $\\hat{A}$, which is defined as rotation by $90^{\\circ}$ about 3-axis with the exchange of valance proton and neutron. We found that both $M1$ and $E2$ transitions are allowed between the levels with different values of $A$, while are forbidden between the levels with same values of $A$. Such a selection rule holds true for M$\\chi$D in different mass regions.
H. Satz(University of Bielefeld)
2000-01-01
At high temperatures or densities, hadronic matter shows different forms of critical behaviour: colour deconfinement, chiral symmetry restoration, and diquark condensation. I first discuss the conceptual basis of these phenomena and then consider the description of colour deconfinement in terms of symmetry breaking, through colour screening and as percolation transition.
Jens O. Andersen; William R. Naylor(Department of Physics, Norwegian University of Science and Technology, Høgskoleringen 5, N-7491 Trondheim, Norway); Anders Tranberg(Faculty of Science and Technology, University of Stavanger, 4036 Stavanger, Norway)
2014-01-01
We use the Polyakov loop coupled quark-meson model to approximate low energy QCD and present results for the chiral and deconfinement transitions in the presence of a constant magnetic background $B$ at finite temperature $T$ and baryon chemical potential $\\mu_B$. We investigate effects of various gluoni potentials on the deconfinement transition with and without a fermionic backreaction at finite $B$. Additionally we investigate the effect of the Polyakov loop on the chiral phase transition,...
Fluctuations and the Phase Transition in a Chiral Model with Polyakov Loops%引入Polyakov环路的手征模型中的涨落与相变
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
We explore the NJL model with Polyakov loops for a system of three colors and two flavors within the mean-field approximation, where both chiral symmetry and confinement are taken into account. We focus on the phase structure of the model and study the chiral and Polyakov loop susceptibilities.
Cosmological phase transitions
Energy Technology Data Exchange (ETDEWEB)
Kolb, E.W. [Fermi National Accelerator Lab., Batavia, IL (United States)]|[Chicago Univ., IL (United States)
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.
VIJ, JAGDISH
2009-01-01
PUBLISHED We investigate both the supercooling and the hysteresis phenomena of the phase transitions between the smectic C* and the smectic C *Aphases driven by temperature and electric field, respectively. These two phenomena show similar characteristics for the dependence of transmittance on both the cell thickness and the applied field. The mechanisms for large supercooling and large hysteresis in thin cells are shown to correspond to the suppression of the propagation of solitary wave ...
Quark-hadron phase transition in massive gravity
Atazadeh, K.
2016-11-01
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.
Polyakov SU(3) extended linear $\\sigma$-model: Sixteen mesonic states in chiral phase-structure
Tawfik, Abdel Nasser
2014-01-01
The derivative of the grand potential in mean field approximation, non-strange and strange condensates and deconfinement phase-transition in thermal and dense hadronic medium are verified in extended SU(3) linear sigma-model (eLSM). In determining the chiral phase-transition, the chiral condensates sigma_x and sigma_y are analysed. The chiral mesonic phase-structures in temperature- and density-dependence are taken as free parameters to be fitted. These parameters are classified corresponding to scalar meson nonets; (pseudo)-scalar and (axial)-vector. For deconfinement phase-transition, effective Polyakov loop-potentials phi and phi^* are utilized. We investigated the in-medium effects on the masses of sixteen mesonic states states. The results are presented for two different forms for the effective Polyakov loop-potential and compared with other models with and without anomalous terms. The Polyakov loop potential in LSM has considerable effects on the chiral phase-transition in meson masses so that the resto...
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.
Chiral transition, eigenmode localisation and Anderson-like models
Giordano, Matteo; Pittler, Ferenc
2016-01-01
We discuss chiral symmetry restoration and eigenmode localisation in finite-temperature QCD by looking at the lattice Dirac operator as a random Hamiltonian. We argue that the features of QCD relevant to both phenomena are the presence of order in the Polyakov line configuration, and the correlations that this induces between spatial links across time slices. This ties the fate of chiral symmetry and of localisation of the lowest Dirac eigenmodes to the confining properties of the theory. We then show numerical results obtained in a QCD-inspired Anderson-like toy model, derived by radically simplifying the QCD dynamics while keeping the important features mentioned above. The toy model reproduces all the important qualitative aspects of chiral symmetry breaking and localisation in QCD, thus supporting the central role played by the confinement/deconfinement transition in triggering both phenomena.
Phase transitions modern applications
Gitterman, Moshe
2014-01-01
This book provides a comprehensive review of the theory of phase transitions and its modern applications, based on the five pillars of the modern theory of phase transitions i.e. the Ising model, mean field, scaling, renormalization group and universality. This expanded second edition includes, along with a description of vortices and high temperature superconductivity, a discussion of phase transitions in chemical reaction and moving systems. The book covers a close connection between phase transitions and small world phenomena as well as scale-free systems such as the stock market and the Internet. Readership: Scientists working in different fields of physics, chemistry, biology and economics as well as teaching material for undergraduate and graduate courses.
Institute of Scientific and Technical Information of China (English)
许可; 李未
1999-01-01
Phase transition is an important feature of SAT problem. For random k-SAT model, it is proved that as r（ratio of clauses to variables） increases, the structure of solutions will undergo a sudden change like satisfiability phase transition when r reaches a threshold point (r=rcr). This phenomenon shows that the satisfying truth assignments suddenly shift from being relatively different from each other to being very similar to each other.##属性不符
Generic Weyl phase in the vortex state of quasi-two-dimensional chiral superconductors
Yoshida, Tomohiro; Udagawa, Masafumi
2016-08-01
We study the collective behavior of Majorana modes in the vortex state of chiral p -wave superconductors. Away from the isolated vortex limit, the zero-energy Majorana states communicate with each other on a vortex lattice, and form a coherent band structure with a nontrivial topological character. We reveal that the topological nature of Majorana bands changes sensitively via quantum phase transitions in two-dimensional (2D) systems, by sweeping magnetic field or Fermi energy. Through the idea of dimensional reduction, we show the existence of a generic superconducting Weyl phase in a low magnetic field region of quasi-2D chiral superconductors.
Phases of N=1 Supersymmetric Chiral Gauge Theories
Energy Technology Data Exchange (ETDEWEB)
Craig, Nathaniel; /Princeton, Inst. Advanced Study /Rutgers U., Piscataway; Essig, Rouven; /Princeton, Inst. Advanced Study /YITP, Stony Brook /SLAC /Stanford U., Phys. Dept.; Hook, Anson; Torroba, Gonzalo; /SLAC /Stanford U., Phys. Dept.
2012-02-17
We analyze the phases of supersymmetric chiral gauge theories with an antisymmetric tensor and (anti)fundamental flavors, in the presence of a classically marginal superpotential deformation. Varying the number of flavors that appear in the superpotential reveals rich infrared chiral dynamics and novel dualities. The dualities are characterized by an infinite family of magnetic duals with arbitrarily large gauge groups describing the same fixed point, correlated with arbitrarily large classical global symmetries that are truncated nonperturbatively. At the origin of moduli space, these theories exhibit a phase with confinement and chiral symmetry breaking, an interacting nonabelian Coulomb phase, and phases where an interacting sector coexists with a sector that either s-confines or is in a free magnetic phase. Properties of these intriguing 'mixed phases' are studied in detail using duality and a-maximization, and the presence of superpotential interactions provides further insights into their formation.
Li, Dongyan; Wu, Xi; Hao, Fangli; Yang, Yang; Chen, Xiaoming
2016-01-01
Eleven kinds of chiral compounds have been well separated within 10 min on polysaccharide derivative-based chiral stationary phases named Chiralpak IA, IB, IC, ID, IE and IF by supercritical fluid chromatography (SFC). The chiral recognition of these chiral compounds has demonstrated good complementary enantioselectivities of the six chiral columns, which were proved to be useful for chiral SFC. Both the elution time and enantioselectivies could be significantly affected by the modifier types and their concentrations, such as methanol, ethanol and isopropanol, which should be optimized during the experiments. In addition, the solvent versatility of the immobilized chiral stationary phase on the optimization of the chiral separation was helpful. PMID:27319169
Transitions of Smectic A to Tilted Phases in Thin Free Standing Films of Liquid Crystal
International Nuclear Information System (INIS)
The transition of orthogonal smectic A (SmA) phase to the tilted phases, upon lowering the temperature, is explored with a discrete phenomenological model and the phase diagrams are presented. The results show that the transition of SmA to uniplanar structures can be affected by the effect of chirality. The areas showing the uniplanar phase in the phase diagrams diminish with the increase in effect of chirality. (author)
Thermodynamic phases and mesonic fluctuations in a chiral nucleon-meson model
Drews, Matthias; Klein, Bertram; Weise, Wolfram
2013-01-01
Studies of the QCD phase diagram must properly include nucleonic degrees of freedom and their thermodynamics in the range of baryon chemical potentials characteristic of nuclear matter. A useful framework for incorporating relevant nuclear physics constraints in this context is a chiral nucleon-meson effective Lagrangian. In the present paper, such a chiral nucleon-meson model is extended with systematic inclusion of mesonic fluctuations using the functional renormalization group approach. The resulting description of the nuclear liquid-gas phase transition shows a remarkable agreement with three-loop calculations based on in-medium chiral effective field theory. No signs of a chiral first-order phase transition and its critical endpoint are found in the region of applicability of the model, at least up to twice the density of normal nuclear matter and at temperatures T<100 MeV. Fluctuations close to the critical point of the first-order liquid-gas transition are also examined with a detailed study of the ...
Susceptibilities and the Phase Structure of a Chiral Model with Polyakov Loops
Sasaki, C.; Friman, B.; Redlich, K.
2006-01-01
In an extension of the Nambu-Jona-Lasinio model where the quarks interact with the temporal gluon field, represented by the Polyakov loop, we explore the relation between the deconfinement and chiral phase transitions. The effect of Polyakov loop dynamics on thermodynamic quantities, on the phase structure at finite temperature and baryon density and on various susceptibilities is presented. Particular emphasis is put on the behavior and properties of the fluctuations of the (approximate) ord...
An Anderson-like model of the QCD chiral transition
Giordano, Matteo; Pittler, Ferenc
2016-01-01
We study the problems of chiral symmetry breaking and eigenmode localisation in finite-temperature QCD by looking at the lattice Dirac operator as a random Hamiltonian. We recast the staggered Dirac operator into an unconventional three-dimensional Anderson Hamiltonian ("Dirac-Anderson Hamiltonian") carrying internal degrees of freedom, with disorder provided by the fluctuations of the gauge links. In this framework, we identify the features relevant to chiral symmetry restoration and localisation of the low-lying Dirac eigenmodes in the ordering of the local Polyakov lines, and in the related correlation between spatial links across time slices, thus tying the two phenomena to the deconfinement transition. We then build a toy model based on QCD and on the Dirac-Anderson approach, replacing the Polyakov lines with spin variables and simplifying the dynamics of the spatial gauge links, but preserving the above-mentioned relevant dynamical features. Our toy model successfully reproduces the main features of the...
Photoinduced phase transitions
Nasu, K
2004-01-01
A new class of insulating solids was recently discovered. Whenirradiated by a few visible photons, these solids give rise to amacroscopic excited domain that has new structural and electronicorders quite different from the starting ground state. This occurrenceis called "photoinduced phase transition", and this multi-authoredbook reviews recent theoretical and experimental studies of this newphenomenon.
Chiral Paramagnetic Skyrmion-like Phase in MnSi
Pappas, C.; Lelièvre-Berna, E.; Falus, P.; Bentley, P.M.; Moskvin, E.; Grigoriev, S.; Fouquet, P.; Farago, B.
2009-01-01
We present a comprehensive study of chiral fluctuations in the reference helimagnet MnSi by polarized neutron scattering and neutron spin echo spectroscopy, which reveals the existence of a completely left-handed and dynamically disordered phase. This phase may be identified as a spontaneous Skyrmio
Deconfinement phase transition in neutron star matter
Institute of Scientific and Technical Information of China (English)
LI Ang; PENG Guang-Xiong; Lombardo U
2009-01-01
The transition from hadron phase to strange quark phase in dense matter is investigated. Instead of using the conventional bag model in quark sect, we achieve the confinement by a density-dependent quark mass derived from in-medium chiral condensates, with a thermodynamic problem improved. In nuclear slot,we adopt the equation of state from Brueckner-Bethe-Goldstone approach with three-body force. It is found that the mixed phase can occur, for reasonable confinement parameter, near the normal saturation density,and transit to pure quark matter at 4-5 times the saturation, which is quite different from the previous results from other quark models that pure quark phase can not appear at neutron-star densities.
Can sigma models describe finite temperature chiral transitions?
Kocic, Aleksandar; Aleksandar KOCIC; John KOGUT
1995-01-01
Large-N expansions and computer simulations indicate that the universality class of the finite temperature chiral symmetry restoration transition in the 3D Gross-Neveu model is mean field theory. This is a counterexample to the standard 'sigma model' scenario which predicts the 2D Ising model universality class. We trace the breakdown of the standard scenario (dimensional reduction and universality) to the absence of canonical scalar fields in the model. We point out that our results could be generic for theories with dynamical symmetry breaking, such as Quantum Chromodynamics.
Emergence and Phase Transitions
Sikkema, Arnold
2006-05-01
Phase transitions are well defined in physics through concepts such as spontaneous symmetry breaking, order parameter, entropy, and critical exponents. But emergence --- also exhibiting whole-part relations (such as top-down influence), unpredictability, and insensitivity to microscopic detail --- is a loosely-defined concept being used in many disciplines, particularly in psychology, biology, philosophy, as well as in physics[1,2]. I will review the concepts of emergence as used in the various fields and consider the extent to which the methods of phase transitions can clarify the usefulness of the concept of emergence both within the discipline of physics and beyond.1. Robert B. Laughlin, A Different Universe: Reinventing Physics from the Bottom Down (New York: Basic Books, 2005). 2. George F.R. Ellis, ``Physics and the Real World'', Physics Today, vol. 58, no. 7 (July 2005) pp. 49-54.
Understanding quantum phase transitions
Carr, Lincoln
2010-01-01
Quantum phase transitions (QPTs) offer wonderful examples of the radical macroscopic effects inherent in quantum physics: phase changes between different forms of matter driven by quantum rather than thermal fluctuations, typically at very low temperatures. QPTs provide new insight into outstanding problems such as high-temperature superconductivity and display fundamental aspects of quantum theory, such as strong correlations and entanglement. Over the last two decades, our understanding of QPTs has increased tremendously due to a plethora of experimental examples, powerful new numerical meth
Peripheral Nucleon-Nucleon Phase Shifts and Chiral Symmetry
Kaiser, N; Weise, W
1997-01-01
Within the one-loop approximation of baryon chiral perturbation theory we calculate all one-pion and two-pion exchange contributions to the nucleon-nucleon interaction. In fact we construct the elastic NN-scattering amplitude up to and including third order in small momenta. The phase shifts with orbital angular momentum $L\\geq2 $ and the mixing angles with $J\\geq2$ are given parameterfree and thus allow for a detailed test of chiral symmetry in the two-nucleon system. We find that for the D-waves the $2\\pi$-exchange corrections are too large as compared with empirical phase shifts, signaling the increasing importance of shorter range effects in lower partial waves. For higher partial waves, especially for G-waves, the model independent $2\\pi$-exchange corrections bring the chiral prediction close to empirical NN phase shifts. We propose to use the chiral NN phase shifts with $L\\geq 3$ as input in a future phase shift analysis. Furthermore, we compute the irreducible two-pion exchange NN-potentials in coordin...
Geometric Phase and Chiral Anomaly in Path Integral Formulation
Fujikawa, Kazuo
2007-01-01
All the geometric phases, adiabatic and non-adiabatic, are formulated in a unified manner in the second quantized path integral formulation. The exact hidden local symmetry inherent in the Schr\\"{o}dinger equation defines the holonomy. All the geometric phases are shown to be topologically trivial. The geometric phases are briefly compared to the chiral anomaly which is naturally formulated in the path integral.
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Several kinds of racemic naproxen ester were successfully separated on CTMB chiral stationary phase with hexane-ethanol (98:2, vol./vol.) as the mobile phase. The influence of mobile phase composition and structure of racemic naproxen ester on chiral separation was studied and the chiral recognition mechanism of CTMB was discussed.
Institute of Scientific and Technical Information of China (English)
BaoHaiSHAO; XiuZhuXU; 等
2002-01-01
Several kinds of racemic naproxen ester were successfully separated on CTMB chiral stationary phase with hexane-ethanol(98:2,vol./vol.) as the mobile phase. The influence of mobile phase composition and structure of racemic naproxen ester on chiral separation was studied and the chiral recognition mechanism of CTMB was discussed.
Phases of (Asymptotically) Safe Chiral Theories with(out) Scalars
Molgaard, Esben
2016-01-01
We unveil the dynamics of four dimensional chiral gauge-Yukawa theories featuring several scalar degrees of freedom transforming according to distinct representations of the underlying gauge group. We consider generalized Georgi-Glashow and Bars-Yankielowicz theories. We determine, to the maximum known order in perturbation theory, the phase diagram of these theories and further disentangle their ultraviolet asymptotic nature according to whether they are asymptotically free or safe. We therefore extend the number of theories that are known to be fundamental in the Wilsonian sense to the case of chiral gauge theories with scalars.
Mass transfer mechanism in chiral reversed phase liquid chromatography.
Gritti, Fabrice; Guiochon, Georges
2014-03-01
The mechanism of mass transfer in chiral chromatography was investigated using an experimental protocol already applied in RPLC and HILIC chromatography. The different contributions to the reduced height equivalent to a theoretical plate (HETP) include the longitudinal diffusion HETP term, the solid-liquid mass transfer resistance HETP term, the short-range eddy dispersion HETP term, and the long-range eddy dispersion HETP term. Their accurate measurement permits the determination of the adsorption rate constant kads of trans-stilbene enantiomers on a column packed with Lux 5 μm Cellulose-1 particles. The experimental results demonstrate that the number of adsorption-desorption steps per unit time of chiral compounds on polysaccharide-based chiral stationary phases is four orders of magnitude smaller than that of achiral compounds.
Phase diagram of 4D field theories with chiral anomaly from holography
Ammon, Martin; Macedo, Rodrigo P
2016-01-01
Within gauge/gravity duality, we study the class of four dimensional CFTs with chiral anomaly described by Einstein-Maxwell-Chern-Simons theory in five dimensions. In particular we determine the phase diagram at finite temperature, chemical potential and magnetic field. At high temperatures the solution is given by an electrically and magnetically charged AdS Reissner-Nordstroem black brane. For sufficiently large Chern-Simons coupling and at sufficiently low temperatures and small magnetic fields, we find a new phase with helical order, breaking translational invariance spontaneously. For the Chern-Simons couplings studied, the phase transition is second order with mean field exponents. Since the entropy density vanishes in the limit of zero temperature we are confident that this is the true ground state which is the holographic version of a chiral magnetic spiral.
QCD Phase Transitions and Bag Constants at Finite Chemical Potential
Institute of Scientific and Technical Information of China (English)
YANG Shu; GUO Hua; ZHAO En-Guang; L(U) Xiao-Fu
2007-01-01
The global colour model at finite temperature is further extended to study the systems at finite chemical potential. The deconfinement and chiral phase transition at finite chemical potential and at temperature T=0K are studied simultaneously. Meanwhile the evolution of the bag constants at finite chemical potential is calculated. The dependences of results on the model parameters are discussed in detail.
Quantum phase transitions in the noncommutative Dirac Oscillator
Panella, O
2014-01-01
We study the (2+1) dimensional Dirac oscillator in a homogeneous magnetic field in the non-commutative plane. It is shown that the effect of non-commutativity is twofold: $i$) momentum non commuting coordinates simply shift the critical value ($B_{\\text{cr}}$) of the magnetic field at which the well known left-right chiral quantum phase transition takes place (in the commuting phase); $ii$) non-commutativity in the space coordinates induces a new critical value of the magnetic field, $B_{\\text{cr}}^*$, where there is a second quantum phase transition (right-left), --this critical point disappears in the commutative limit--. The change in chirality associated with the magnitude of the magnetic field is examined in detail for both critical points. The phase transitions are described in terms of the magnetisation of the system. Possible applications to the physics of silicene and graphene are briefly discussed.
Chiral rings and phases of supersymmetric gauge theories
International Nuclear Information System (INIS)
We solve for the expectation values of chiral operators in supersymmetric U(N) gauge theories with matter in the adjoint, fundamental and anti-fundamental representations. A simple geometric picture emerges involving a description by a meromorphic one-form on a Riemann surface. The equations of motion are equivalent to a condition on the integrality of periods of this form. The solution indicates that all semiclassical phases with the same number of U(1) factors are continuously connected. (author)
Learning phase transitions by confusion
van Nieuwenburg, Evert P L; Huber, Sebastian D
2016-01-01
Classifying phases of matter is a central problem in physics. For quantum mechanical systems, this task can be daunting owing to the exponentially large Hilbert space. Thanks to the available computing power and access to ever larger data sets, classification problems are now routinely solved using machine learning techniques. Here, we propose to use a neural network based approach to find phase transitions depending on the performance of the neural network after training it with deliberately incorrectly labelled data. We demonstrate the success of this method on the topological phase transition in the Kitaev chain, the thermal phase transition in the classical Ising model, and the many-body-localization transition in a disordered quantum spin chain. Our method does not depend on order parameters, knowledge of the topological content of the phases, or any other specifics of the transition at hand. It therefore paves the way to a generic tool to identify unexplored phase transitions.
[Enantioseparation behavior of chiral stationary phases AD, AS and OD].
Li, Liqun; Fan, Jun; Zhang, Jing; Chen, Xiaodong; Wang, Tai; He, Jianfeng; Zhang, Weiguang
2016-01-01
Over the past decades, HPLC enantioseparation with chiral stationary phases (CSPs) has been widely applied in chiral analysis and preparation of new pharmaceuticals, pesticides, food, etc. Herein, enantioseparation of 20 chiral compounds have been carried out on three polysaccharide-based CSPs (EnantioPak AD, AS and OD) with normal phases by HPLC, separately. The influences of skeletal structure and the kinds of derivative groups on separation behaviors of these CSPs have been studied in detail. As results indicated, except for compound 13, the other compounds were baseline separated on EnantioPak AD, with most of resolution over 2. 0; in addition, better separation for acidic or basic compounds was achieved through adding acidic/basic additives into the mobile phase of hexane-alcohol. For four aromatic alcohols (compounds 13-16), their retention in the EnantioPak AD column showed a weakening tendency with increase of carbon number in side chain group, and the reverse trend of their resolution was observed. Furthermore, EnantioPak AD showed much better separation performance for eight compounds (13-20) than the others. In short, these results have provided some references for further investigation of separation behavior and applications of polysaccharide-based CSPs. PMID:27319174
Quantum phase transition in space
Energy Technology Data Exchange (ETDEWEB)
Damski, Bogdan [Los Alamos National Laboratory; Zurek, Wojciech H [Los Alamos National Laboratory
2008-01-01
A quantum phase transition between the symmetric (polar) phase and the phase with broken symmetry can be induced in a ferromagnetic spin-1 Bose-Einstein condensate in space (rather than in time). We consider such a phase transition and show that the transition region in the vicinity of the critical point exhibits scalings that reflect a compromise between the rate at which the transition is imposed (i.e., the gradient of the control parameter) and the scaling of the divergent healing length in the critical region. Our results suggest a method for the direct measurement of the scaling exponent {nu}.
Institute of Scientific and Technical Information of China (English)
陈晓青; 刘莉; 焦飞鹏; 王珍
2012-01-01
In order to obtain a better enantioselectivity of phenylalanine enantiomers and establish the optimal chiral ex- traction conditions, the distribution behavior was investigated in aqueous two-phase systems which were composed of polyethylene glycol and ammonium sulfate containing combinatorial chiral selector： β-cyclodextrin and HP-β-cyclodextrin. The influence of the molar concentration ratio of combinatorial chiral selectors, the total molar concentration of combinatorial chiral selectors, pH value, buffer type and its concentration were thoroughly studied, respectively. The results show that the enantioselectivity reaches 1.53 under the optimal chiral extraction conditions This extraction is a potential economical and effective way for chiral resolution.
Quantum phase transitions of topological insulators without gap closing.
Rachel, Stephan
2016-10-12
We consider two-dimensional Chern insulators and time-reversal invariant topological insulators and discuss the effect of perturbations breaking either particle-number conservation or time-reversal symmetry. The appearance of trivial mass terms is expected to cause quantum phase transitions into trivial phases when such a perturbation overweighs the topological term. These phase transitions are usually associated with a bulk-gap closing. In contrast, the chiral Chern insulator is unaffected by particle-number breaking perturbations. Moreover, the [Formula: see text] topological insulator undergoes phase transitions into topologically trivial phases without bulk-gap closing in the presence of any of such perturbations. In certain cases, these phase transitions can be circumvented and the protection restored by another U(1) symmetry, e.g. due to spin conservation. These findings are discussed in the context of interacting topological insulators. PMID:27530509
Energy Technology Data Exchange (ETDEWEB)
Park, Soohyun; Kim, Sang Jun; Hyun, Myung Ho [Pusan National Univ., Busan (Korea, Republic of)
2012-10-15
Optically active chiral amines are important as building blocks for pharmaceuticals and as scaffolds for chiral ligands and, consequently, many efforts have been devoted to the development of efficient methods for their preparation. For example, reduction of amine precursors with chiral catalysts, enzymatic kinetic resolution or dynamic kinetic resolution of racemic amines and the direct amination of ketones with transaminases have been developed as the efficient methods for the preparation of optically active chiral amines. During the process of developing or utilizing optically active chiral amines, the methods for the determination of their enantiomeric composition are essential. Among various methods, liquid chromatographic resolution of enantiomers on chiral stationary phases (CSPs) have been known to be one of the most accurate and economic means for the determination of the enantiomeric composition of optically active chiral compounds. Especially, CSPs based on chiral crown ethers have been successfully used for the resolution of racemic primary amines. For example, CSPs based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (CSP 1, Figure 1) or (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6 (CSP 2 and CSP 3, Figure 1) have been known to be quite effective for the resolution of cyclic and non-cyclic amines, various fluoroquinolone antibacterials containing a primary amino group, tocainide (antiarrhythmic agent) and its analogues, aryl-a-amino ketones and 3-amino-1,4-benzodiazepin-2-ones.
Magnetic resonance of phase transitions
Owens, Frank J; Farach, Horacio A
1979-01-01
Magnetic Resonance of Phase Transitions shows how the effects of phase transitions are manifested in the magnetic resonance data. The book discusses the basic concepts of structural phase and magnetic resonance; various types of magnetic resonances and their underlying principles; and the radiofrequency methods of nuclear magnetic resonance. The text also describes quadrupole methods; the microwave technique of electron spin resonance; and the Mössbauer effect. Phase transitions in various systems such as fluids, liquid crystals, and crystals, including paramagnets and ferroelectrics, are also
Multiobjective Optimization and Phase Transitions
Seoane, Luís F
2015-01-01
Many complex systems obey to optimality conditions that are usually not simple. Conflicting traits often interact making a Multi Objective Optimization (MOO) approach necessary. Recent MOO research on complex systems report about the Pareto front (optimal designs implementing the best trade-off) in a qualitative manner. Meanwhile, research on traditional Simple Objective Optimization (SOO) often finds phase transitions and critical points. We summarize a robust framework that accounts for phase transitions located through SOO techniques and indicates what MOO features resolutely lead to phase transitions. These appear determined by the shape of the Pareto front, which at the same time is deeply related to the thermodynamic Gibbs surface. Indeed, thermodynamics can be written as an MOO from where its phase transitions can be parsimoniously derived; suggesting that the similarities between transitions in MOO-SOO and Statistical Mechanics go beyond mere coincidence.
NN Scattering Phase Shifts in a Chiral Constituent Quark Model
Bartz, D.; Stancu, Fl
2000-01-01
We study the nucleon-nucleon interaction within a chiral constituent quark model which reproduces succesfully the baryon spectra. We calculate the 3S1 and 1S0 phase shifts by using the resonating group method. They clearly indicate the presence of a strong repulsive interaction at short distance, due to the spin-flavor symmetry of the quark-quark interaction and of the quark interchange between the two interacting nucleons. A sigma-exchange quark-quark interaction, providing a medium-range at...
QCD phase transitions via a refined truncation of Dyson-Schwinger equations
Gao, Fei
2016-01-01
We investigate both the chiral and deconfinement phase transitions of QCD matter in a refined scheme of Dyson-Schwinger equations, which have been shown to be successful in giving the meson mass spectrum and matching the interaction with the results from ab initio computation. We verify the equivalence of the chiral susceptibility criterion with different definitions for the susceptibility and confirm that the chiral susceptibility criterion is efficient to fix not only the chiral phase boundary but also the critical end point (CEP), especially when one could not have the effective thermodynamical potential. We propose a generalized Schwinger function criterion for the confinement. We give the phase diagram of both phase transitions and show that in the refined scheme the position of the CEP shifts to lower chemical potential and higher temperature. Based on our calculation and previous results of the chemical freeze out conditions, we propose that the CEP locates in the states of the matter generated by the ...
Vortex driven phase transition in Topologically Massive QED
Hoshino, Yuichi
2016-01-01
There is chiral like symmetry for 4-component massless fermion in (2+1)-dimensional gauge theory.Since QED$_{3}$ with Chern-Simons term contains vortex solution for vector potential,one may expect vortex driven phase transition as Kosterlitz-Thouless type where chiral condensate is washed away at zero temperature.To study this possibility,we evaluate the fermion propagator by Dyson-Schwinger equation numerically and spectral function analytically in the Landau gauge.For quenched case we adopt Ball-Chiu vertex to keep gauge invariance of the results.The critical value of topological mass,above which chiral condensate washed away, turned out to be $O(10^{-2})e^{2}$ at least for weak coupling in both cases.
Phase transitions and dark matter problems
International Nuclear Information System (INIS)
The possible relationships between phase transitions in the early universe and dark matter problems are discussed. It is shown that there are at least 3 distinct cosmological dark matter problems 1) halos; 2) galaxy formation and clustering; and 3) Ω = 1, each emphasizing different attributes for the dark matter. At least some of the dark matter must by baryonic but if problems 2 and 3 are real they seem to also require non-baryonic material. However, if seeds are generated at the quark-hadron-chiral symmetry transition then alternatives to the standard scenarios may occur. At present no simple simultaneous solution (neither ''hot'', ''warm'', nor ''cold'') exists for all 3 problems, but non-standard solutions with strings, decaying particles or light not tracing to mass may work. An alternative interpretation of the relationship of the cluster-cluster and galaxy-galaxy correlation functions using renormalized scaling is mentioned. In this interpretation galaxies are more strongly correlated and the cluster-cluster function is not expected to go negative until > or approx. 200 Mpc. Possible phase transition origins for the cluster-cluster renormalized scale are presented as ways to obtain a dimension 1.2 fractal. (orig.)
Wagdy, Hebatallah A; Hanafi, Rasha S; El-Nashar, Rasha M; Aboul-Enein, Hassan Y
2013-09-01
Pharmaceutical companies worldwide tend to apply chiral chromatographic separation techniques in their mass production strategy rather than asymmetric synthesis. The present work aims to investigate the predictability of chromatographic behavior of enantiomers using DryLab HPLC method development software, which is typically used to predict the effect of changing various chromatographic parameters on resolution in the reversed phase mode. Three different types of chiral stationary phases were tested for predictability: macrocyclic antibiotics-based columns (Chirobiotic V and T), polysaccharide-based chiral column (Chiralpak AD-RH), and protein-based chiral column (Ultron ES-OVM). Preliminary basic runs were implemented, then exported to DryLab after peak tracking was accomplished. Prediction of the effect of % organic mobile phase on separation was possible for separations on Chirobiotic V for several probes: racemic propranolol with 97.80% accuracy; mixture of racemates of propranolol and terbutaline sulphate, as well as, racemates of propranolol and salbutamol sulphate with average 90.46% accuracy for the effect of percent organic mobile phase and average 98.39% for the effect of pH; and racemic warfarin with 93.45% accuracy for the effect of percent organic mobile phase and average 99.64% for the effect of pH. It can be concluded that Chirobiotic V reversed phase retention mechanism follows the solvophobic theory. PMID:23775938
Phenomenology of cosmic phase transitions
International Nuclear Information System (INIS)
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
Quantum Phase Transition, Dissipation, and Measurement
Chakravarty, Sudip
2009-01-01
A selected set of topics in quantum phase transition is discussed. It includes dissipative quantum phase transitions, the role of disorder, and the relevance of quantum phase transition to measurement theory in quantum mechanics.
Chiral two-body currents in nuclei: Gamow-Teller transitions and neutrinoless double-beta decay
Menéndez, J.; Gazit, D.; Schwenk, A.
2011-01-01
We show that chiral effective field theory (EFT) two-body currents provide important contributions to the quenching of low-momentum-transfer Gamow-Teller transitions, and use chiral EFT to predict the momentum-transfer dependence that is probed in neutrinoless double-beta decay. We then calculate for the first time the neutrinoless double-beta decay operator based on chiral EFT currents and study the nuclear matrix elements at successive orders. The contributions from chiral two-body currents...
Phase transitions in field theory
International Nuclear Information System (INIS)
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)
Institute of Scientific and Technical Information of China (English)
2011-01-01
Two coated-type composite chiral stationary phases (CSPs) were prepared based on cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) and amylose tris (3,5-dimethylphenylcarbamate)(ADMPC) by coating the corresponding derivatives onto 3-aminopropyl silica gel separately and then mixing or by coating the mixed derivatives onto silica gel. The CSPs containing only CDMPC or ADMPC were also prepared for comparison. The mixing method does not significantly influence the enantioselectivities. The composite CSPs generally show chiral recognition abilities intermediate between those of the two individual phases, while some racemates were poorer and at the same time one was better resolved on the composite CSPs.
Chern-Simons diffusion rate across different phase transitions
Rougemont, Romulo; Finazzo, Stefano Ivo
2016-05-01
We investigate how the dimensionless ratio given by the Chern-Simons diffusion rate ΓCS divided by the product of the entropy density s and temperature T behaves across different kinds of phase transitions in the class of bottom-up nonconformal Einstein-dilaton holographic models originally proposed by Gubser and Nellore. By tuning the dilaton potential, one is able to holographically mimic a first order, a second order, or a crossover transition. In a first order phase transition, ΓCS/s T jumps at the critical temperature (as previously found in the holographic literature), while in a second order phase transition it develops an infinite slope. On the other hand, in a crossover, ΓCS/s T behaves smoothly, although displaying a fast variation around the pseudo-critical temperature. In all the cases, ΓCS/s T increases with decreasing T . The behavior of the Chern-Simons diffusion rate across different phase transitions is expected to play a relevant role for the chiral magnetic effect around the QCD critical end point, which is a second order phase transition point connecting a crossover band to a line of first order phase transition. Our findings in the present work add to the literature the first predictions for the Chern-Simons diffusion rate across second order and crossover transitions in strongly coupled nonconformal, non-Abelian gauge theories.
Incommensurate phase transitions
Energy Technology Data Exchange (ETDEWEB)
Currat, R. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)
1996-11-01
We review the characteristic aspects of modulated crystals from the point of view of inelastic neutron scattering. We discuss the phenomenological Landau theory of the normal-to-incommensurate displacive instability and its predictions concerning the fluctuation spectrum of the modulated phase. General results on the form of the normal-mode eigenvectors and on the inelastic scattering channels through which they couple to the probe are established using the superspace approach. We illustrate these results on a simple discrete model symmetry and we review available inelastic neutron scattering data on several displacively modulated compounds. (author) 21 figs., 73 refs.
Enantioseparation of Timolol on a Novel β-Cyclodextrin Derivative Chiral Stationary Phase in HPLC.
Zhou, Jie; Sun, Fang; Du, Qiuzheng; Zhao, Suzhen; Pei, Wenjuan
2016-01-01
A novel chiral stationary phase was prepared by bonding a novel β-cyclodextrin derivative on silica gel, and it was used for the separation of timolol in high efficiency liquid phase. In the reverse mode, the factors such as the proportion of chiral additives, flow rate, column temperature, repeatability and stability were investigated. The optimum chromatographic conditions are as follows: column temperature was 25°C, flow rate was 0.6 mL min(-1) and mobile phase was methanol-25 mM KH2PO4 (80/20, v/v). The chiral column has good reproducibility (Rs = 4.49, 4.51 and 4.40, respectively) and a certain degree of stability (Rs = 4.49, 3.01 and 0.72, respectively). This chiral stationary phase presented good chiral recognition performance toward timolol with good resolution (Rs = 4.49).
Phase transition in evolutionary games
Cao, Z J; Cao, Zhen; Hwa, Rudolph C
1995-01-01
The evolution of cooperative behaviour is studied in the deterministic version of the Prisoners' Dilemma on a two-dimensional lattice. The payoff parameter is set at the critical region 1.8 < b < 2.0 , where clusters of cooperators are formed in all spatial sizes. Using the factorial moments developed in particle and nuclear physics for the study of phase transition, the distribution of cooperators is studied as a function of the bin size covering varying numbers of lattice cells. From the scaling behaviour of the moments a scaling exponent is determined and is found to lie in the range where phase transitions are known to take place in physical systems. It is therefore inferred that when the payoff parameter is increased through the critical region the biological system of cooperators undergoes a phase transition to defectors. The universality of the critical behaviour is thus extended to include also this particular model of evolution dynamics.
Interface Effect in QCD Phase Transitions via Dyson-Schwinger Equation Approach
Gao, Fei
2016-01-01
With the chiral susceptibility criterion we obtain the phase diagram of strong-interaction matter in terms of temperature and chemical potential in the framework of Dyson-Schwinger equations (DSEs) of QCD.After calculating the pressure and some other thermodynamic properties of the matter in the DSE method, we get the phase diagram in terms of temperature and baryon number density. We also obtain the interface tension and the interface entropy density to describe the inhomogeneity of the two phases in the coexistence region of the first order phase transition. After including the interface effect, we find that the total entropy density of the system increases in both the deconfinement (dynamical chiral symmetry restoration) and the hadronization (dynamical chiral symmetry breaking) processes of the first order phase transitions and thus solve the entropy puzzle in the hadronization process.
Fischer, Tobias; Hempel, Matthias
2016-01-01
The thermodynamic bag model (tdBag) has been applied widely to model quark matter properties in both heavy-ion and astrophysics communities. Several fundamental physics aspects are missing in tdBag, e.g., dynamical chiral symmetry breaking (D$\\chi$SB) and repulsions due to the vector interaction are both included explicitly in the novel vBag quark matter model of Kl\\"ahn and Fischer (2015) (Astrophys. J. 810, 134 (2015)). An important feature of vBag is the simultaneous D$\\chi$SB and deconfinement, where the latter links vBag to a given hadronic model for the construction of the phase transition. In this article we discuss the extension to finite temperatures and the resulting phase diagram for the isospin symmetric medium.
Wang, Dongqiang; Zhao, Jianchao; Wu, Haixia; Wu, Haibo; Cai, Jianfeng; Ke, Yanxiong; Liang, Xinmiao
2015-01-01
The C9-position of quinine was modified by meta- or para-substituted benzo-18-crown-6, and immobilized on 3-mercaptopropyl-modified silica gel through the radical thiol-ene addition reaction. These two chiral stationary phases were evaluated by chiral acids, amino acids, and chiral primary amines. The crown ether moiety on the quinine anion exchanger provided a ligand-exchange site for primary amino groups, which played an important role in the retention and enantioselectivity for chiral compounds containing primary amine groups. These two stationary phases showed good selectivity for some amino acids. The complex interaction between crown ether and protonated primary amino group was investigated by the addition of inorganic salts such as LiCl, NH4Cl, NaCl, and KCl to the mobile phase. The resolution results showed that the simultaneous interactions between two function moieties (quinine and crown ether) and amino acids were important for the chiral separation.
Non-uniform chiral phase studied within the Polyakov NJL model
Partyka, Tomasz L.
2010-01-01
We consider how does the introduction of a Polyakov loop affects the spatially inhomogeneous quark condensate. The primary result of our work is that the existence of the spatially non-uniform chiral phase is confirmed within the Polyakov NJL model in a chiral limit. These findings are obtained both in a 3d-cutoff and in a Schwinger (proper time) regularization schemes.
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)
Artificiality of multifractal phase transitions
Wolf, Martin; Schmiegel, Jürgen; Greiner, Martin
1999-01-01
A multifractal phase transition is associated to a nonanalyticity in the generalised dimensions. We show that its occurrence is an artifact of the asymptotic scaling behaviour of integral moments and that it is not observed in an analysis based on differential n-point correlation densities.
Phase transitions in quantum chromodynamics
Meyer-Ortmanns, H
1996-01-01
The current understanding of finite temperature phase transitions in QCD is reviewed. A critical discussion of refined phase transition criteria in numerical lattice simulations and of analytical tools going beyond the mean-field level in effective continuum models for QCD is presented. Theoretical predictions about the order of the transitions are compared with possible experimental manifestations in heavy-ion collisions. Various places in phenomenological descriptions are pointed out, where more reliable data for QCD's equation of state would help in selecting the most realistic scenario among those proposed. Unanswered questions are raised about the relevance of calculations which assume thermodynamic equilibrium. Promising new approaches to implement nonequilibrium aspects in the thermodynamics of heavy-ion collisions are described.
Pairing Phase Transitions of Matter under Rotation
Jiang, Yin
2016-01-01
The phases and properties of matter under global rotation have attracted much interest recently. In this paper we investigate the pairing phenomena in a system of fermions under the presence of rotation. We find that there is a generic suppression effect on pairing states with zero angular momentum. We demonstrate this effect with the chiral condensation and the color superconductivity in hot dense QCD matter as explicit examples. In the case of chiral condensation, a new phase diagram in the temperature-rotation parameter space is found, with a nontrivial critical point.
The helical phase of chiral nematic liquid crystals as the Bianchi VII(0) group manifold
Gibbons, G W
2011-01-01
We show that the optical structure of the helical phase of a chiral nematic is naturally associated with the Bianchi VII(0) group manifold. The Joets-Ribotta metric governing propagation of the extraordinary rays is invariant under the simply transitive action of the universal cover of the three dimensional Euclidean group of two dimensions. Thus extraordinary light rays are geodesics of a left-invariant metric on this Bianchi type VII(0) group. We are able to solve by separation of variables both the wave equation and the Hamilton-Jacobi equation for this metric. The former reduces to Mathieu's equation and the later to the quadrantal pendulum equation. We further discuss Maxwell's equations for uniaxial optical materials where the configuration is invariant under a group action. The material is not assumed to be impedance matched, thus going beyond the usual scope of transformation optics. We show that for a chiral nematic in its helical phase Maxwell's equations reduce to a generalised Mathieu equation. Ou...
Chiral gap effect in curved space
Flachi, Antonino
2014-01-01
We discuss a new type of QCD phenomenon induced in curved space. In the QCD vacuum a mass gap of Dirac fermions is attributed to the spontaneous breaking of chiral symmetry. If the curvature is positive large, the chiral condensate melts but a chiral invariant mass gap can still remain, which we name the chiral gap effect in curved space. This leads to decoupling of quark deconfinement which implies a view of black holes surrounded by a first-order QCD phase transition.
Phase transitions and critical phenomena
Domb, Cyril
2001-01-01
The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. It has moved into a central place in condensed matter studies.Statistical physics, and more specifically, the theory of transitions between states of matter, more or less defines what we know about 'everyday' matter and its transformations.The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable in
Liquid Crystal Phases of Molecular Bananas: Polarity and Chirality as Broken Symmetries
Clark, Noel
2006-03-01
The study of the interplay of chirality and polarity has been a particularly rich theme of soft matter science since Meyer's seminal discovery that tilted smectics of chiral molecules are macroscopically polar. This event, and the subsequent realization of polar domains and high-speed electro-optic switching in chiral smectics, engaged the liquid crystal community in a worldwide pursuit of novel smectics for applications, featured by the synthesis of more than 50,000 new liquid crystal compounds, and by a consequent broad diversification of the palette of liquid crystal phases and possibilities for supermolecular ordering. A current important activity in this scenario is the study of polar order in synthetically achiral molecules, for example, in molecular bananas, which, as their shape suggests, might be expected to organize in a polar way. Indeed they do, but beyond this, almost everything learned about them has been surprising, including their persistent tendency to exhibit chirality as a spontaneously broken symmetry. I will discuss some of these new phases and phenomena, including the discovery of fluid conglomerates (Pasteur's experiment in a fluid), triclinic fluid order, chiral twist grain boundary phases of achiral molecules, chirality flipping and field-induced deracemization, ferroelectric and antiferroelectric phases with supermolecular- scale polarization modulation, and chiral thermotropic sponge phases.
Chiral perturbation theory study of the axial $N\\to\\Delta(1232)$ transition
Geng, L S; Alvarez-Ruso, L; Vacas, M J Vicente
2008-01-01
We have performed a theoretical study of the axial Nucleon to Delta(1232) ($N\\to\\Delta$) transition form factors up to one-loop order in covariant baryon chiral perturbation theory within a formalism in which the unphysical spin-1/2 components of the $\\Delta$ fields are decoupled.
Phase Transitions in the Universe
Gleiser, Marcello
1998-01-01
During the past two decades, cosmologists turned to particle physics in order to explore the physics of the very early Universe. The main link between the physics of the smallest and largest structures in the Universe is the idea of spontaneous symmetry breaking, familiar from condensed matter physics. Implementing this mechanism into cosmology leads to the interesting possibility that phase transitions related to the breaking of symmetries in high energy particle physics took place during the early history of the Universe. These cosmological phase transitions may help us understand many of the challenges faced by the standard hot Big Bang model of cosmology, while offering a unique window into the very early Universe and the physics of high energy particle interactions.
Detection of Zak phases and topological invariants in a chiral photonic quantum walk
Cardano, F; Dauphin, A; Maffei, M; Piccirillo, B; de Lisio, C; De Filippis, G; Cataudella, V; Santamato, E; Marrucci, L; Lewenstein, M; Massignan, P
2016-01-01
Topological insulators are fascinating states of matter exhibiting protected edge states and robust quantized features in their bulk. Here, we propose and validate experimentally a method to detect topological properties in the bulk of one-dimensional chiral systems. We first introduce the mean chiral displacement, and we show that it rapidly approaches a multiple of the Zak phase in the long time limit. Then we measure the Zak phase in a photonic quantum walk, by direct observation of the mean chiral displacement in its bulk. Next, we measure the Zak phase in an alternative, inequivalent timeframe, and combine the two windings to characterize the full phase diagram of this Floquet system. Finally, we prove the robustness of the measure by introducing dynamical disorder in the system. This detection method is extremely general, as it can be applied to all one-dimensional platforms simulating static or Floquet chiral systems.
Transition State Models for Understanding the Origin of Chiral Induction in Asymmetric Catalysis.
Sunoj, Raghavan B
2016-05-17
In asymmetric catalysis, a chiral catalyst bearing chiral center(s) is employed to impart chirality to developing stereogenic center(s). A rich and diverse set of chiral catalysts is now available in the repertoire of synthetic organic chemistry. The most recent trends point to the emergence of axially chiral catalysts based on binaphthyl motifs, in particular, BINOL-derived phosphoric acids and phosphoramidites. More fascinating ideas took shape in the form of cooperative multicatalysis wherein organo- and transition-metal catalysts are made to work in concert. At the heart of all such manifestations of asymmetric catalysis, classical or contemporary, is the stereodetermining transition state, which holds a perennial control over the stereochemical outcome of the catalytic process. Delving one step deeper, one would find that the origin of the stereoselectivity is delicately dependent on the relative stabilization of one transition state, responsible for the formation of the predominant stereoisomer, over the other transition state for the minor stereoisomer. The most frequently used working hypothesis to rationalize the experimentally observed stereoselectivity places an undue emphasis on steric factors and tends to regard the same as the origin of facial discrimination between the prochiral faces of the reacting partners. In light of the increasing number of asymmetric catalysts that rely on hydrogen bonding as well as other weak non-covalent interactions, it is important to take cognizance of the involvement of such interactions in the sterocontrolling transition states. Modern density functional theories offer a pragmatic and effective way to capture non-covalent interactions in transition states. Aided by the availability of such improved computational tools, it is quite timely that the molecular origin of stereoselectivity is subjected to more intelligible analysis. In this Account, we describe interesting molecular insights into the stereocontrolling
Transition State Models for Understanding the Origin of Chiral Induction in Asymmetric Catalysis.
Sunoj, Raghavan B
2016-05-17
In asymmetric catalysis, a chiral catalyst bearing chiral center(s) is employed to impart chirality to developing stereogenic center(s). A rich and diverse set of chiral catalysts is now available in the repertoire of synthetic organic chemistry. The most recent trends point to the emergence of axially chiral catalysts based on binaphthyl motifs, in particular, BINOL-derived phosphoric acids and phosphoramidites. More fascinating ideas took shape in the form of cooperative multicatalysis wherein organo- and transition-metal catalysts are made to work in concert. At the heart of all such manifestations of asymmetric catalysis, classical or contemporary, is the stereodetermining transition state, which holds a perennial control over the stereochemical outcome of the catalytic process. Delving one step deeper, one would find that the origin of the stereoselectivity is delicately dependent on the relative stabilization of one transition state, responsible for the formation of the predominant stereoisomer, over the other transition state for the minor stereoisomer. The most frequently used working hypothesis to rationalize the experimentally observed stereoselectivity places an undue emphasis on steric factors and tends to regard the same as the origin of facial discrimination between the prochiral faces of the reacting partners. In light of the increasing number of asymmetric catalysts that rely on hydrogen bonding as well as other weak non-covalent interactions, it is important to take cognizance of the involvement of such interactions in the sterocontrolling transition states. Modern density functional theories offer a pragmatic and effective way to capture non-covalent interactions in transition states. Aided by the availability of such improved computational tools, it is quite timely that the molecular origin of stereoselectivity is subjected to more intelligible analysis. In this Account, we describe interesting molecular insights into the stereocontrolling
Chiral two-body currents in nuclei: Gamow-Teller transitions and neutrinoless double-beta decay.
Menéndez, J; Gazit, D; Schwenk, A
2011-08-01
We show that chiral effective field theory (EFT) two-body currents provide important contributions to the quenching of low-momentum-transfer Gamow-Teller transitions, and use chiral EFT to predict the momentum-transfer dependence that is probed in neutrinoless double-beta (0νββ) decay. We then calculate for the first time the 0νββ decay operator based on chiral EFT currents and study the nuclear matrix elements at successive orders. The contributions from chiral two-body currents are significant and should be included in all calculations. PMID:21902315
The Wigner solution and QCD phase transitions in a modified PNJL model
Energy Technology Data Exchange (ETDEWEB)
Cui, Zhu-fang [Nanjing University, Department of Physics, Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Nanjing (China); State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, CAS, Beijing (China); Shi, Chao [Nanjing University, Department of Physics, Nanjing (China); State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, CAS, Beijing (China); Sun, Wei-min; Zong, Hong-shi [Nanjing University, Department of Physics, Nanjing (China); Joint Center for Particle, Nuclear Physics and Cosmology, Nanjing (China); State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, CAS, Beijing (China); Wang, Yong-long [Nanjing University, Department of Physics, Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Nanjing (China); Linyi University, Department of Physics, School of Science, Linyi (China); Massachusetts Institute of Technology, Center for Theoretical Physics, Cambridge, MA (United States)
2014-02-15
By employing some modification to the widely used two-flavor Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model, we discuss the Wigner solution of the quark gap equation at finite temperature and zero quark chemical potential beyond the chiral limit, and then we try to explore its influence on the chiral and deconfinement phase transitions of QCD at finite temperature and zero chemical potential. The discovery of the coexistence of the Nambu and the Wigner solutions of the quark gap equation with nonzero current quark mass at zero temperature and zero chemical potential, as well as their evolutions with temperature, is very interesting for the studies of the phase transitions of QCD. According to our results, the chiral phase transition might be of first order (while the deconfinement phase transition is still a crossover, as in the normal PNJL model), and the corresponding phase transition temperature is lower than that of the deconfinement phase transition, instead of coinciding with each other, which are not the same as the conclusions obtained from the normal PNJL model. In addition, we also discuss the sensibility of our final results on the choice of model parameters. (orig.)
De Klerck, Katrijn; Vander Heyden, Yvan; Mangelings, Debby
2014-02-01
Since their introduction on the market the applicability of immobilized polysaccharide-based chiral stationary phases in high-performance liquid chromatography has been thoroughly investigated. These immobilized phases have the benefit to be applicable with a wide range of modifiers, potentially extending the application range of the polysaccharide-based stationary phases. Because an increasing number of stationary phases are being introduced in the field of chiral chromatography it is important to evaluate their enantioselectivity in different techniques in order to get an idea about their applicability. In this study, three immobilized chiral polysaccharide-based stationary phases (Chiralpak IA, IB, and IC) are evaluated in supercritical fluid chromatography (SFC) with a test set of pharmaceutical racemates. This is done in a three-fold manner: their performance is evaluated (1) using traditional modifiers, (2) using mixtures of atypical modifiers, and (3) the results were compared to those on coated stationary phases with an equivalent chiral selector. To get a visual overview of the enantioselective patterns of the different chromatographic systems (mobile and stationary phase combinations), a Principal Component Analysis is performed, which allows determining the (dis)similarity between individual systems. To assess the complementarity cumulative success rates are determined. The immobilized chiral stationary phases prove to yield high cumulative success rates. PMID:24438871
Beesley, Thomas E.
Development of chiral separations has been essential to the drug discovery and development process. The solubility requirements for a number of methods and/or the mobile phase requirements for application of certain detection systems have opened up many opportunities for cyclodextrin-based CSPs for liquid chromatography. Even though a few chiral stationary phases cover a wide area of enantioselectivity, they do not meet the entire needs of the industry. Cyclodextrin phases offer some unique mechanisms and opportunities to resolve chiral separation problems especially in the aqueous reversed-phase and non-aqueous polar organic modes. This chapter addresses the need to understand the chiral stationary phase structure, the mechanisms at work, and the role mobile phase composition plays in driving those mechanisms to produce enantioselectivity. In addition, the development of certain derivatives has played an essential part in expanding that basic role for certain chiral separations. What these derivatives contribute in concert with the basic structure is a critical part of the understanding to the effective use of these phases. During this study it was determined that the role of steric hindrance has been vastly underestimated, both to the extent that it has occurred and to its effectiveness for obtaining enantioselectivity. References to the entire 20-year history of the cyclodextrin phase development and application literature up to this current date have been reviewed and incorporated.
Zhang, Xiaoli; Wang, Litao; Dong, Shuqing; Zhang, Xia; Wu, Qi; Zhao, Liang; Shi, Yanping
2016-05-01
Nanocrystalline cellulose (NCC) with high surface area and high ordered crystalline structure was prepared from microcrystalline cellulose (MCC) under the hydrolysis of sodium hypochlorite. NCC was further reacted with 3,5-dimethylphenyl isocyanate to obtain the nanocellulose derivative, and then coated successfully on the surface of silica gel to a prepared NCC-coated chiral stationary phase (CSP) as a new kind of chiral separation material. Similarly, MCC derivative-coated CSP was also prepared as contrast. The chiral separation performance of NCC-based CSP was evaluated and compared with MCC-based CSP by high-performance liquid chromatography. Moreover, the effects of the alcohol modifiers, mobile phase additives, and flow rates on chiral separations were investigated in detail. The results showed that 10 chiral compounds were separated on NCC-based CSP with better peak shape and higher column efficiency than MCC-based CSP, which confirmed that NCC-based CSP was a promising packing material for the resolution of chiral compounds.Chirality 28:376-381, 2016. © 2016 Wiley Periodicals, Inc. PMID:26949227
Zhang, Xiaoli; Wang, Litao; Dong, Shuqing; Zhang, Xia; Wu, Qi; Zhao, Liang; Shi, Yanping
2016-05-01
Nanocrystalline cellulose (NCC) with high surface area and high ordered crystalline structure was prepared from microcrystalline cellulose (MCC) under the hydrolysis of sodium hypochlorite. NCC was further reacted with 3,5-dimethylphenyl isocyanate to obtain the nanocellulose derivative, and then coated successfully on the surface of silica gel to a prepared NCC-coated chiral stationary phase (CSP) as a new kind of chiral separation material. Similarly, MCC derivative-coated CSP was also prepared as contrast. The chiral separation performance of NCC-based CSP was evaluated and compared with MCC-based CSP by high-performance liquid chromatography. Moreover, the effects of the alcohol modifiers, mobile phase additives, and flow rates on chiral separations were investigated in detail. The results showed that 10 chiral compounds were separated on NCC-based CSP with better peak shape and higher column efficiency than MCC-based CSP, which confirmed that NCC-based CSP was a promising packing material for the resolution of chiral compounds.Chirality 28:376-381, 2016. © 2016 Wiley Periodicals, Inc.
International Nuclear Information System (INIS)
We calculate the temperature T and angular (θ, ϕ) dependencies of the upper critical induction Bc2(θ, ϕ, T) for parallel-spin superconductors with an axially symmetric p-wave pairing interaction pinned to the lattice and a dominant ellipsoidal Fermi surface (FS). For all FS anisotropies, the chiral Scharnberg–Klemm (SK) state Bc2(θ, ϕ, T) exceeds that of the chiral Anderson–Brinkman–Morel (ABM) state and exhibits a kink at θ = θ*(T, ϕ), indicative of a first-order transition from its chiral, nodal-direction behavior to its non-chiral, antinodal-direction behavior. Applicabilities to Sr2RuO4, UCoGe and the candidate topological superconductor CuxBi2Se3 are discussed. (fast track communication)
Phase Transition in Tensor Models
Delepouve, Thibault
2015-01-01
Generalizing matrix models, tensor models generate dynamical triangulations in any dimension and support a $1/N$ expansion. Using the intermediate field representation we explicitly rewrite a quartic tensor model as a field theory for a fluctuation field around a vacuum state corresponding to the resummation of the entire leading order in $1/N$ (a resummation of the melonic family). We then prove that the critical regime in which the continuum limit in the sense of dynamical triangulations is reached is precisely a phase transition in the field theory sense for the fluctuation field.
Phase transitions and critical phenomena
Domb, Cyril
2000-01-01
The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. No longer an area of specialist interest, it has acquired a central focus in condensed matter studies. 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 information on important recent developments.The two review articles in this volume complement each other in a remarkable way. Both deal with what m
Light scattering near phase transitions
Cummins, HZ
1983-01-01
Since the development of the laser in the early 1960's, light scattering has played an increasingly crucial role in the investigation of many types of phase transitions and the published work in this field is now widely dispersed in a large number of books and journals.A comprehensive overview of contemporary theoretical and experimental research in this field is presented here. The reviews are written by authors who have actively contributed to the developments that have taken place in both Eastern and Western countries.
Two-color QCD with chiral chemical potential
Braguta, V. V.; Goy, V. A.; Ilgenfritz, E.-M.; Kotov, A. Yu.; Molochkov, A. V.; Müller-Preussker, M.; Petersson, B.; Schreiber, A.
2016-01-01
The phase diagram of two-color QCD with a chiral chemical potential is studied on the lattice. The focus is on the confinement/deconfinement phase transition and the breaking/restoration of chiral symmetry. The simulations are carried out with dynamical staggered fermions without rooting. The dependence of the Polyakov loop, the chiral condensate and the corresponding susceptibilities on the chiral chemical potential and the temperature are presented.
Phase diagram of the chiral magnet Cr1 /3NbS2 in a magnetic field
Tsuruta, K.; Mito, M.; Deguchi, H.; Kishine, J.; Kousaka, Y.; Akimitsu, J.; Inoue, K.
2016-03-01
We construct the phase diagram of the chiral magnet Cr1 /3NbS2 in a dc magnetic field (Hdc) using ac magnetic susceptibility measurements. At Hdc=0 , the ac response at the transition from the helical magnetic (HM) state to the paramagnetic (PM) state consists of a giant third-order harmonic component (M3 ω) and a first-order harmonic component (M1 ω). By applying Hdc perpendicular to the c axis, the HM state is transformed to the chiral soliton lattice (CSL) state, which is a superlattice tuned by Hdc. The above giant M3 ω is markedly suppressed at small Hdc. The CSL state is found to consist of CSL-1, with dominant helical texture and a poor ferromagnetic array, and CSL-2, with a large ferromagnetic array. The transition between CSL-1 and the PM state causes a linear magnetic response, the dominant component of which is the in-phase M1 ω. With increasing temperature, CSL-2 is transformed into the forced ferromagnetic (FFM) state, and ultimately the PM state is reached. The transition between CSL-2 and the FFM state consists of a large M3 ω and large out-of-phase M1 ω as well as in-phase M1 ω. The transition between the FMM and PM states also yields a linear magnetic response, like the CSL-1-PM-state transition. Five typical magnetic dynamics in the transitions among the HM state, CSL-1, CSL-2, FFM state, and PM state were identified according to the equivalent dynamical motion equation of a nonlinear spring model.
Volume phase transitions of cholesteric liquid crystalline gels
Energy Technology Data Exchange (ETDEWEB)
Matsuyama, Akihiko, E-mail: matuyama@bio.kyutech.ac.jp [Department of Bioscience and Bioinformatics, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka 820-8502 (Japan)
2015-05-07
We present a mean field theory to describe anisotropic deformations of a cholesteric elastomer without solvent molecules and a cholesteric liquid crystalline gel immersed in isotropic solvents at a thermal equilibrium state. Based on the neoclassical rubber theory of nematic elastomers, we derive an elastic energy and a twist distortion energy, which are important to determine the shape of a cholesteric elastomer (or gel). We demonstrate that when the elastic energy dominates in the free energy, the cholesteric elastomer causes a spontaneous compression in the pitch axis and elongates along the director on the plane perpendicular to the pitch axis. Our theory can qualitatively describe the experimental results of a cholesteric elastomer. We also predict the first-order volume phase transitions and anisotropic deformations of a gel at the cholesteric-isotropic phase transition temperature. Depending on a chirality of a gel, we find a prolate or oblate shape of cholesteric gels.
Light sterile neutrinos from a late phase transition
Vecchi, Luca
2016-01-01
Light sterile neutrinos represent a well-motivated extension of the 3-neutrino paradigm. However, the impressive agreement between standard cosmology and data casts doubts on their existence. Here we present a class of scenarios that robustly avoids this tension. In these models the sterile neutrinos are light, chiral states of a new sector interacting with the Standard Model via the right-handed neutrino portal and, crucially, active-sterile neutrino oscillations require a phase transition in the hidden sector. We explore the hidden-couplings/critical-temperature plane and identify regions where several sterile neutrinos can be accommodated. A late phase transition is usually preferred and may also ward off a potential threat posed by the formation of topologically stable defects.
Xiaoli Zhang; Litao Wang; Shuqing Dong; Xia Zhang; Qi Wu; Liang Zhao; Yanping Shi
2016-01-01
Core-shell silica microspheres with a nanocellulose derivative in the hybrid shell were successfully prepared as a chiral stationary phase by a layer-by-layer self-assembly method. The hybrid shell assembled on the silica core was formed using a surfactant as template by the copolymerization reaction of tetraethyl orthosilicate and the nanocellulose derivative bearing triethoxysilyl and 3,5-dimethylphenyl groups. The resulting nanocellulose hybrid core-shell chiral packing materials (CPMs) we...
Institute of Scientific and Technical Information of China (English)
Xiao Ping Chen; Zhi Ming Zhou; Hao Yuan; Zi Hui Meng
2008-01-01
A novel chiral stationary phase (CSP) was prepared by immobilizing mono(6A-N-1-(2-hydroxyl)-phenylethylimino-6A-deoxy)-β-cyclodextrin onto the surface of silica gel via a longer spacer.This chiral stationary phase exhibited good enantios electivity for a variety of chiral compounds under reversed-phase conditions.
Interacting Weyl fermions: Phases, phase transitions and global phase diagram
Roy, Bitan; Juricic, Vladimir
2016-01-01
We study the effects of short-range interactions on a generalized three-dimensional Weyl semimetal, where the band touching points act as the (anti)monopoles of Abelian Berry curvature of strength $n$. We show that any local interaction has a \\emph{negative} scaling dimension $-2/n$. Consequently all Weyl semimetals are stable against weak short-range interactions. For sufficiently strong interactions, we demonstrate that the Weyl semimetal either undergoes a first order transition into a band insulator or a continuous transition into a symmetry breaking phase. A translational symmetry breaking axion insulator and a rotational symmetry breaking semimetal are two prominent candidates for the broken symmetry phase. At one loop level, the correlation length exponent for continuous transitions is $\
Nucleon-to-Delta axial transition form factors in relativistic baryon chiral perturbation theory
Geng, L S; Alvarez-Ruso, L; Vacas, M J Vicente
2008-01-01
We report a theoretical study of the axial Nucleon to Delta(1232) ($N\\to\\Delta$) transition form factors up to one-loop order in relativistic baryon chiral perturbation theory. We adopt a formalism in which the $\\Delta$ couplings obey the spin-3/2 gauge symmetry and, therefore, decouple the unphysical spin-1/2 fields. We compare the results with phenomenological form factors obtained from neutrino bubble chamber data and in quark models.
QCD Phase Transitions, Volume 15
Energy Technology Data Exchange (ETDEWEB)
Schaefer, T.; Shuryak, E.
1999-03-20
The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theorists working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.
Landau-Peierls instability in a Fulde-Ferrell type inhomogeneous chiral condensed phase
Lee, Tong-Gyu; Tsue, Yasuhiko; Tatsumi, Toshitaka; Friman, Bengt
2015-01-01
We investigate the stability of an inhomogeneous chiral condensed phase against low energy fluctuations about a spatially modulated order parameter. This phase corresponds to the so-called dual chiral density wave in the context of quark matter, where the chiral condensate is spatially modulated with a finite wavevector in a single direction. From the symmetry viewpoint, the phase realizes a locking of flavor and translational symmetries. Starting with a Landau-Ginzburg-Wilson effective Lagrangian, we find that the associated Nambu-Goldstone modes, whose dispersion relations are spatially anisotropic and soft in the direction normal to the wavevector of the modulation, wash out the long-range order at finite temperatures, but support algebraically decaying long-range correlations. This implies that the phase can exhibit a quasi-one-dimensional order as in liquid crystals.
Addadi, Khadidja; Sekkoum, Khaled; Belboukhari, Nasser; Cheriti, Abdelkrim; Aboul-Enein, Hassan Y
2015-05-01
Nine β-aminoketones were synthesized via Mannich reaction when benzaldehyde was condensed with some primary amines and acetophenone. The purified compounds were identified by using spectroscopic methods. The enantiomeric separation of these derivatives was carried out by high-performance liquid chromatography (HPLC) using several coated and immobilized polysaccharide stationary phases, namely, Chiralcel(®) OD-H, Chiralcel(®) OD, Chiralcel(®) OJ, Chiralpak(®) AD, Chiralpak(®) IA, and Chiralpak(®) IB using different mobile phases composed of n-hexane and alcohol mixed in various ratios or pure ethanol or isopropanol. The retention behavior and selectivity of these chiral stationary phases were examined in isocratic normal phase mode. The results indicate that cellulose derivatives have higher enantioselectivity than amylose derivatives for the separation of racemic β-amino ketones. PMID:25752940
Cloud regimes as phase transitions
Stechmann, Samuel N.; Hottovy, Scott
2016-06-01
Clouds are repeatedly identified as a leading source of uncertainty in future climate predictions. Of particular importance are stratocumulus clouds, which can appear as either (i) closed cells that reflect solar radiation back to space or (ii) open cells that allow solar radiation to reach the Earth's surface. Here we show that these clouds regimes -- open versus closed cells -- fit the paradigm of a phase transition. In addition, this paradigm characterizes pockets of open cells as the interface between the open- and closed-cell regimes, and it identifies shallow cumulus clouds as a regime of higher variability. This behavior can be understood using an idealized model for the dynamics of atmospheric water as a stochastic diffusion process. With this new conceptual viewpoint, ideas from statistical mechanics could potentially be used for understanding uncertainties related to clouds in the climate system and climate predictions.
Chiral magnetic effect in the PNJL model
Fukushima, Kenji; Gatto, Raoul
2010-01-01
We study the two-flavor Nambu--Jona-Lasinio model with the Polyakov loop (PNJL model) in the presence of a strong magnetic field and a chiral chemical potential $\\mu_5$ which mimics the effect of imbalanced chirality due to QCD instanton and/or sphaleron transitions. Firstly we focus on the properties of chiral symmetry breaking and deconfinement crossover under the strong magnetic field. Then we discuss the role of $\\mu_5$ on the phase structure. Finally the chirality charge, electric current, and their susceptibility, which are relevant to the Chiral Magnetic Effect, are computed in the model.
Pleiner, Harald; Brand, Helmut R
2014-02-01
We discuss the symmetry properties as well as the dynamic behavior of various non-polar nematic liquid crystal phases with tetrahedral order. We concentrate on systems that show biaxial nematic order coexisting with octupolar (tetrahedral) order. Non-polar examples are phases with D2 and S4 symmetries, which can be characterized as biaxial nematics lacking inversion symmetry. It is this combination that allows for new features in the statics and dynamics of these phases. The D2-symmetric phase is chiral, even for achiral molecules, and shows ambidextrous chirality in all three preferred directions. The achiral S4-symmetric phase allows for ambidextrous helicity, similar to the higher-symmetric D2d-symmetric phase. Such phases are candidates for nematic phases made from banana-shaped molecules.
Takahashi, Y.; Eby, P. B.
1985-01-01
Possibilities of observing abundances of phi mesons and narrow hadronic pairs, as results of QGP and Chiral transitions, are considered for nucleus-nucleus interactions. Kinematical requirements in forming close pairs are satisfied in K+K decays of S(975) and delta (980) mesons with small phi, and phi (91020) mesons with large PT, and in pi-pi decays of familiar resonance mesons only in a partially restored chiral symmetry. Gluon-gluon dominance in QGP can enhance phi meson production. High hadronization rates of primordial resonance mesons which form narrow hadronic pairs are not implausible. Past cosmic ray evidences of anomalous phi production and narrow pair abundances are considered.
Spontaneous magnetization of quark matter in the inhomogeneous chiral phase
Directory of Open Access Journals (Sweden)
R. Yoshiike
2015-12-01
Full Text Available Considering the density wave of scalar and pseudoscalar condensates, we study the response of quark matter to a weak external magnetic field. In an external magnetic field, the energy spectrum of the lowest Landau level becomes asymmetric about zero, which is closely related to chiral anomaly, and gives rise to the spontaneous magnetization. This mechanism may be one of candidates for the origin of the strong magnetic field in pulsars and/or magnetars.
Spontaneous magnetization of quark matter in the inhomogeneous chiral phase
Yoshiike, Ryo; Tatsumi, Tositaka
2015-01-01
Considering the density wave of scalar and pseudoscalar condensates, we study the response of quark matter to a weak external magnetic field. In an external magnetic field, the energy spectrum of the lowest Landau level becomes asymmetric about zero, which is closely related to chiral anomaly, and gives rise to the spontaneous magnetization. This mechanism may be one of candidates for the origin of the strong magnetic field in pulsars and/or magnetars.
Magnetic Phase Transition in FeRh
Gu, R. Y.; Antropov, V.P.
2005-01-01
Density functional calculations are performed to investigate the phase transition in FeRh alloy. The effective exchange coupling, the critical temperature of magnetic phase transition and the adiabatic spin wave spectrum have been obtained. Different contributions to the free energy of different phases are estimated. It has been found that the antiferro-ferromagnetic transition in FeRh occurs mostly due to the spin wave excitations.
Berry phase of light Bragg-reflected by chiral liquid crystal media
Barboza, Raouf; Residori, Stefania; Clerc, Marcel G
2016-01-01
Berry phase is revealed for circularly polarized light when it is Bragg-reflected by a chiral liquid crystal medium of the same handedness. By using a chiral nematic layer we demonstrate that if the input plane of the layer is rotated with respect to a fixed reference frame, then, a geometric phase effect occurs for the circularly polarized light reflected by the periodic helical structure of the medium. Theory and numerical simulations are supported by an experimental observation, disclosing novel applications in the field of optical manipulation and fundamental optical phenomena.
Berry Phase of Light under Bragg Reflection by Chiral Liquid-Crystal Media.
Barboza, Raouf; Bortolozzo, Umberto; Clerc, Marcel G; Residori, Stefania
2016-07-29
A Berry phase is revealed for circularly polarized light when it is Bragg reflected by a chiral liquid-crystal medium of the same handedness. By using a chiral nematic layer we demonstrate that if the input plane of the layer is rotated with respect to a fixed reference frame, a geometric phase effect occurs for the circularly polarized light reflected by the periodic helical structure of the medium. Theory and numerical simulations are supported by an experimental observation, disclosing novel applications in the field of optical manipulation and fundamental optical phenomena. PMID:27517773
Directory of Open Access Journals (Sweden)
Xiaoli Zhang
2016-05-01
Full Text Available Core-shell silica microspheres with a nanocellulose derivative in the hybrid shell were successfully prepared as a chiral stationary phase by a layer-by-layer self-assembly method. The hybrid shell assembled on the silica core was formed using a surfactant as template by the copolymerization reaction of tetraethyl orthosilicate and the nanocellulose derivative bearing triethoxysilyl and 3,5-dimethylphenyl groups. The resulting nanocellulose hybrid core-shell chiral packing materials (CPMs were characterized and packed into columns, and their enantioseparation performance was evaluated by high performance liquid chromatography. The results showed that CPMs exhibited uniform surface morphology and core-shell structures. Various types of chiral compounds were efficiently separated under normal and reversed phase mode. Moreover, chloroform and tetrahydrofuran as mobile phase additives could obviously improve the resolution during the chiral separation processes. CPMs still have good chiral separation property when eluted with solvent systems with a high content of tetrahydrofuran and chloroform, which proved the high solvent resistance of this new material.
Zhang, Xiaoli; Wang, Litao; Dong, Shuqing; Zhang, Xia; Wu, Qi; Zhao, Liang; Shi, Yanping
2016-01-01
Core-shell silica microspheres with a nanocellulose derivative in the hybrid shell were successfully prepared as a chiral stationary phase by a layer-by-layer self-assembly method. The hybrid shell assembled on the silica core was formed using a surfactant as template by the copolymerization reaction of tetraethyl orthosilicate and the nanocellulose derivative bearing triethoxysilyl and 3,5-dimethylphenyl groups. The resulting nanocellulose hybrid core-shell chiral packing materials (CPMs) were characterized and packed into columns, and their enantioseparation performance was evaluated by high performance liquid chromatography. The results showed that CPMs exhibited uniform surface morphology and core-shell structures. Various types of chiral compounds were efficiently separated under normal and reversed phase mode. Moreover, chloroform and tetrahydrofuran as mobile phase additives could obviously improve the resolution during the chiral separation processes. CPMs still have good chiral separation property when eluted with solvent systems with a high content of tetrahydrofuran and chloroform, which proved the high solvent resistance of this new material. PMID:27153055
Phase transitions in semidefinite relaxations.
Javanmard, Adel; Montanari, Andrea; Ricci-Tersenghi, Federico
2016-04-19
Statistical inference problems arising within signal processing, data mining, and machine learning naturally give rise to hard combinatorial optimization problems. These problems become intractable when the dimensionality of the data is large, as is often the case for modern datasets. A popular idea is to construct convex relaxations of these combinatorial problems, which can be solved efficiently for large-scale datasets. Semidefinite programming (SDP) relaxations are among the most powerful methods in this family and are surprisingly well suited for a broad range of problems where data take the form of matrices or graphs. It has been observed several times that when the statistical noise is small enough, SDP relaxations correctly detect the underlying combinatorial structures. In this paper we develop asymptotic predictions for several detection thresholds, as well as for the estimation error above these thresholds. We study some classical SDP relaxations for statistical problems motivated by graph synchronization and community detection in networks. We map these optimization problems to statistical mechanics models with vector spins and use nonrigorous techniques from statistical mechanics to characterize the corresponding phase transitions. Our results clarify the effectiveness of SDP relaxations in solving high-dimensional statistical problems. PMID:27001856
Effect of Single-walled Carbon Nanotubes on Cellulose Phenylcarbamate Chiral Stationary Phases
Institute of Scientific and Technical Information of China (English)
CHANG Yin-xia; REN Chao-xing; RUAN Qiong; YUAN Li-ming
2007-01-01
Single-walled carbon nanotubes(SWNTs) have a high adsorption ability and nanoscale interactions. Cellulose trisphenylcarbamates possess high enantioseparation ability in high-performance liquid chromatography(HPLC). Single-walled carbon nanotubes mixed with cellulose trisphenylcarbamate are coated on the silica gel as chiral stationary phases and higher enantioseparation factors are obtained. After a single-walled carbon nanotube is linked to the 6-position of cellulose 2,3-bisphenylcarbamate, its enantioseparation resolution increases compared to that of the cellulose trisphenylcarbamate. It is the first time that SWNTs have been applied to enantioseparation. The results indicate that the single-walled carbon nanotubes are good promoters of chiral recognition. This method can be used to improve the enantioseparation efficiency of the polysaccharide chiral stationary phases.
The high density QCD phase transition in compact stars
Energy Technology Data Exchange (ETDEWEB)
Pagliara, Giuseppe; Hempel, Matthias; Schaffner-Bielich, Jurgen [Institut fuer Theoretische Physik, Ruprecht-Karls-Universitaet, Philosophenweg 16, D-69120, Heidelberg (Germany); Sagert, Irina [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Max von Laue-Str. 1, D-60438 Frankfurt (Germany)
2010-07-01
The study of the QCD phase diagram at high density is still in its infancy. A promising source of experimental informations comes from the physics of neutron stars, the core of which might reach densities up to ten times nuclear matter density. We review the different possible signals from neutrons stars which bring informations about the equation of state of strongly interacting matter from their birth, in a Supernova explosion, to the deleptonization era and the early or late cooling, to eventually their final instants of life within the merger process in binary systems. A special emphasis is put on the modeling of the equation of state of matter from sub-saturation densities up to the large densities at which the chiral phase transition is believed to occur.
International Nuclear Information System (INIS)
Overlap fermions are particularly well suited to study the finite temperature dynamics of the chiral symmetry restoration transition of QCD, which might be just an analytic crossover. Using gauge field configurations on a 243 x 10 lattice with Nf=2 flavours of dynamical Wilson-clover quarks generated by the DIK collaboration, we compute the lowest 50 eigenmodes of the overlap Dirac operator and try to locate the transition by fermionic means. We analyse the spectral density, local chirality and localisation properties of the low-lying modes and illustrate the changing topological and (anti-) selfdual structure of the underlying gauge fields across the transition. (orig.)
Tawfik, Abdel Nasser
2015-01-01
Effects of external magnetic field on various properties of the quantum chromodynamics under extreme conditions of temperature and density have been analysed. To this end, we use SU(3) Polyakov linear sigma-model and assume that the external magnetic field eB adds some restrictions to the quarks energy due to the existence of free charges in the plasma phase. In doing this, we apply the Landau theory of quantization. This requires an additional temperature to drive the system through the chiral phase-transition. Accordingly, the dependence of the critical temperature of chiral and confinement phase-transitions on the magnetic field is characterized. Based on this, we have studied the thermal evolution of thermodynamic quantities and the first four higher-order moment of particle multiplicity. Having all these calculations, we have studied the effects of magnetic field on chiral phase-transition. We found that both critical temperature T_c and critical chemical potential increase with increasing the magnetic f...
Spontaneous Magnetization of Quark Matter in Inhomogeneous Chiral Phase
Yoshiike, Ryo; Tatsumi, Toshitaka
2015-01-01
Considering the density wave of scalar and pseudoscalar condensates, we study the response of quark matter to a weak external magnetic field. In an external magnetic field, the energy spectrum of the lowest Landau level becomes asymmetric about zero, which is closely related to chiral anomaly. This spectral asymmetry gives rise to spontaneous magnetization. This mechanism may be one of candidates for the origin of the strong magnetic field in magnetars. Furthermore, using the generalized Ginzburg-Landau(gGL) expansion, we show that magnetic susceptibility exhibits a peculiar feature
The Structural Phase Transition in Solid DCN
DEFF Research Database (Denmark)
Dietrich, O. W.; Mackenzie, Gordon A.; Pawley, G. S.
1976-01-01
Neutron scattering measurements on deuterated hydrogen cyanide have shown that the structural phase transition from a tetragonal to an orthorhombic form at 160 K is a first order transition. A transverse acoustic phonon mode, which has the symmetry of the transition was observed at very low energ...
Quantum Phase Transitions in a Finite System
Leviatan, A
2006-01-01
A general procedure for studying finite-N effects in quantum phase transitions of finite systems is presented and applied to the critical-point dynamics of nuclei undergoing a shape-phase transition of second-order (continuous), and of first-order with an arbitrary barrier.
Shape Transitions and Chiral Symmetry Breaking in the Energy Landscape of the Mitotic Chromosome.
Zhang, Bin; Wolynes, Peter G
2016-06-17
We derive an unbiased information theoretic energy landscape for chromosomes at metaphase using a maximum entropy approach that accurately reproduces the details of the experimentally measured pairwise contact probabilities between genomic loci. Dynamical simulations using this landscape lead to cylindrical, helically twisted structures reflecting liquid crystalline order. These structures are similar to those arising from a generic ideal homogenized chromosome energy landscape. The helical twist can be either right or left handed so chiral symmetry is broken spontaneously. The ideal chromosome landscape when augmented by interactions like those leading to topologically associating domain formation in the interphase chromosome reproduces these behaviors. The phase diagram of this landscape shows that the helical fiber order and the cylindrical shape persist at temperatures above the onset of chiral symmetry breaking, which is limited by the topologically associating domain interaction strength.
Shape Transitions and Chiral Symmetry Breaking in the Energy Landscape of the Mitotic Chromosome
Zhang, Bin; Wolynes, Peter G.
2016-06-01
We derive an unbiased information theoretic energy landscape for chromosomes at metaphase using a maximum entropy approach that accurately reproduces the details of the experimentally measured pairwise contact probabilities between genomic loci. Dynamical simulations using this landscape lead to cylindrical, helically twisted structures reflecting liquid crystalline order. These structures are similar to those arising from a generic ideal homogenized chromosome energy landscape. The helical twist can be either right or left handed so chiral symmetry is broken spontaneously. The ideal chromosome landscape when augmented by interactions like those leading to topologically associating domain formation in the interphase chromosome reproduces these behaviors. The phase diagram of this landscape shows that the helical fiber order and the cylindrical shape persist at temperatures above the onset of chiral symmetry breaking, which is limited by the topologically associating domain interaction strength.
Shape Transitions and Chiral Symmetry Breaking in the Energy Landscape of the Mitotic Chromosome
Zhang, Bin
2015-01-01
We derive an unbiased information theoretic energy landscape for chromosomes at metaphase using a maximum entropy approach that accurately reproduces the details of the experimentally measured pair-wise contact probabilities between genomic loci. Dynamical simulations using this landscape lead to cylindrical, helically twisted structures reflecting liquid crystalline order. These structures are similar to those arising from a generic ideal homogenized chromosome energy landscape. The helical twist can be either right or left handed so chiral symmetry is broken spontaneously. The ideal chromosome landscape when augmented by interactions like those leading to topologically associating domain (TAD) formation in the interphase chromosome reproduces these behaviors. The phase diagram of this landscape shows the helical fiber order and the cylindrical shape persist at temperatures above the onset of chiral symmetry breaking which is limited by the TAD interaction strength.
Reflective Spin-Orbit Geometric Phase from Chiral Anisotropic Optical Media.
Rafayelyan, Mushegh; Tkachenko, Georgiy; Brasselet, Etienne
2016-06-24
We report on highly reflective spin-orbit geometric phase optical elements based on a helicity-preserving circular Bragg-reflection phenomenon. First, we present a dynamical geometric phase experiment using a flat chiral Bragg mirror. Then, we show that shaping such a geometric phase allows the efficient spin-orbit tailoring of light fields without the need to fulfill any condition on birefringent phase retardation, in contrast to the case of transmission spin-orbit optical elements. This is illustrated by optical vortex generation from chiral liquid crystal droplets in the Bragg regime that unveils spin-orbit consequences of the droplet's curvature. Our results thus introduce a novel class of geometric phase elements-"Bragg-Berry" optical elements. PMID:27391723
Institute of Scientific and Technical Information of China (English)
Ze-da Xu; Yong Zhang; Xing-he Fan; Xin-hua Wan; Qi-feng Zhou
2002-01-01
An optically active monomer containing azobenzene moieties with chiral group (s-2-methyl-butyl), 4-[2-(methacryloyloxy)ethyloxy]-4'-(s-2-methyl-1-butyloxycarbonyl) azobenzene (M1) was synthesized. Polymer (PM1) possessing optical phase conjugated response was obtained by homopolymerization of the optically active monomer (M1) using free radical polymerization. The polymer was very soluble in common solvents and good optical quality films could be easily fabricated by spin coating. The optical phase conjugated responses of the polymer PM1 were measured by degenerate four-wave mixing (DFWM). In comparison with polymer containing no chiral group, it was found from the preliminary measurement of photoisomeric change that optical phase conjugated response of the PM1 in the long-range order hexagonal symmetry microstructure could be easily controlled by choosing the appropriate polarization direction of the irradiating beams (514.5 nm) and the irradiating number, presumably due to the chiral group in the PM1 molecular structure. For the case of the polymer investigated here, a chiral group side chain was introduced to increase optical phase conjugated response intensity with different polarization directions of the irradiating beams, which aims originally at searching for a new photoactive material.
Switchable thermal antenna by phase transition
Ben-Abdallah, Philippe; Besbes, Mondher
2013-01-01
We introduce a thermal antenna which can be actively switched by phase transition. The source makes use of periodically patterned vanadium dioxide, a metal-insulator phase transition material which supports a surface phonon-polariton (SPP) in the infrared range in its crystalline phase. Using electrodes properly registred with respect to the pattern, the phase transition of VO2 can be localy triggered within few microseconds and the SPP can be diffracted making the thermal emission highly directionnal. This switchable antenna could find broad applications in the domain of active thermal coatings or in those of infrared spectroscopy and sensing.
Inhomogeneous nucleation in quark hadron phase transition
Shukla, P K; Sen-Gupta, S K; Gleiser, Marcello; Gleiser, Marcelo
2000-01-01
The effect of subcritical hadron bubbles on a first-order quark-hadron phase transition is studied. These subcritical hadron bubbles created due to thermal fluctuations introduce a finite amount of phase mixing (quark phase mixed with hadron phase) even at and above the critical temperature. For sufficiently strong transitions, as is expected to be the case for the quark-hadron transition, we show that the amount of phase mixing at the critical temperature remains much below the percolation threshold. Thus, as the system cools below the critical temperature, the transition proceeds through the nucleation of critical-size hadron bubbles from a metastable quark-gluon phase (QGP) within an inhomogeneous background populated by an equilibrium distribution of subcritical hadron bubbles. The inhomogenity of the medium is incorporated consistently by modelling the subcritical bubbles as Gaussian fluctuations, resulting in a large reduction of the nucleation barrier for the critical bubbles. Using the corrected nucle...
Synthetic-gauge-field stabilization of the chiral-spin-liquid phase
Chen, Gang; Hazzard, Kaden R. A.; Rey, Ana Maria; Hermele, Michael
2016-06-01
We explore the phase diagram of the SU (N ) Hubbard models describing fermionic alkaline-earth-metal atoms in a square optical lattice with, on average, one atom per site, using a slave rotor mean-field approach. We find that the chiral spin liquid (CSL) predicted for N ≥5 and large interactions passes through a fractionalized state with a spinon Fermi surface as interactions are decreased before transitioning to a weakly interacting metal. We show that by adding a uniform artificial gauge field with 2 π /N flux per plaquette, the CSL becomes the ground state for all N ≥3 at intermediate interactions, persists to weaker interactions, and exhibits a larger spin gap. For N ≥5 we find the CSL is the ground state everywhere the system is a Mott insulator. The gauge field stabilization of the CSL at lower interactions, and thus at weaker lattice depths, together with the increased spin gap, can relax the temperature constraints required for its experimental realization in ultracold atom systems.
Intersubband-transition-induced phase matching
Almogy, Gilad; Segev, Mordechai; Yariv, Amnon
1994-01-01
We suggest the use of the refractive-index changes associated with the intersubband transitions in quantum wells for phase matching in nonlinear materials. An improvement in the conversion efficiency of mid-IR second-harmonic generation by almost 2 orders of magnitude over non-phase-matched bulk GaAs is predicted. We also show that the linear phase contributions of intersubband transitions used for resonant enhancement of second-harmonic generation must be considered, as they could limit the ...
Zhao, Licong; Yang, Limin; Wang, Qiuquan
2016-05-13
Glutathione (GSH)-, somatostatin acetate (ST)- and ovomucoid (OV)-functionalized silica-monolithic stationary phases were designed and synthesized for HILIC and chiral separation using capillary electrochromatography (CEC). GSH, ST and OV were covalently incorporated into the silica skeleton via the epoxy ring-opening reaction between their amino groups and the glycidyl moiety in γ-glycidoxypropyltrimethoxysilane (GPTMS) together with polycondensation and copolymerization of tetramethyloxysilane and GPTMS. Not only could the direction and electroosmotic flow magnitude on the prepared GSH-, ST- and OV-silica hybrid monolithic stationary phases be controlled by the pH of the mobile phase, but also a typical HILIC behavior was observed so that the nucleotides and HPLC peptide standard mixture could be baseline separated using an aqueous mobile phase without any acetonitrile during CEC. Moreover, the prepared monolithic columns had a chiral separation ability to separate dl-amino acids. The OV-silica hybrid monolithic column was most effective in chiral separation and could separate dl-glutamic acid (Glu) (the resolution R=1.07), dl-tyrosine (Tyr) (1.57) and dl-histidine (His) (1.06). Importantly, the chiral separation ability of the GSH-silica hybrid monolithic column could be remarkably enhanced when using gold nanoparticles (AuNPs) to fabricate an AuNP-mediated GSH-AuNP-GSH-silica hybrid monolithic column. The R of dl-Glu, dl-Tyr and dl-His reached 1.19, 1.60 and 2.03. This monolithic column was thus applied to separate drug enantiomers, and quantitative separation of all four R/S drug enantiomers were achieved with R ranging from 4.36 to 5.64. These peptide- and protein-silica monolithic stationary phases with typical HILIC separation behavior and chiral separation ability implied their promise for the analysis of not only the future metabolic studies, but also drug enantiomers recognition.
Zhao, Licong; Yang, Limin; Wang, Qiuquan
2016-05-13
Glutathione (GSH)-, somatostatin acetate (ST)- and ovomucoid (OV)-functionalized silica-monolithic stationary phases were designed and synthesized for HILIC and chiral separation using capillary electrochromatography (CEC). GSH, ST and OV were covalently incorporated into the silica skeleton via the epoxy ring-opening reaction between their amino groups and the glycidyl moiety in γ-glycidoxypropyltrimethoxysilane (GPTMS) together with polycondensation and copolymerization of tetramethyloxysilane and GPTMS. Not only could the direction and electroosmotic flow magnitude on the prepared GSH-, ST- and OV-silica hybrid monolithic stationary phases be controlled by the pH of the mobile phase, but also a typical HILIC behavior was observed so that the nucleotides and HPLC peptide standard mixture could be baseline separated using an aqueous mobile phase without any acetonitrile during CEC. Moreover, the prepared monolithic columns had a chiral separation ability to separate dl-amino acids. The OV-silica hybrid monolithic column was most effective in chiral separation and could separate dl-glutamic acid (Glu) (the resolution R=1.07), dl-tyrosine (Tyr) (1.57) and dl-histidine (His) (1.06). Importantly, the chiral separation ability of the GSH-silica hybrid monolithic column could be remarkably enhanced when using gold nanoparticles (AuNPs) to fabricate an AuNP-mediated GSH-AuNP-GSH-silica hybrid monolithic column. The R of dl-Glu, dl-Tyr and dl-His reached 1.19, 1.60 and 2.03. This monolithic column was thus applied to separate drug enantiomers, and quantitative separation of all four R/S drug enantiomers were achieved with R ranging from 4.36 to 5.64. These peptide- and protein-silica monolithic stationary phases with typical HILIC separation behavior and chiral separation ability implied their promise for the analysis of not only the future metabolic studies, but also drug enantiomers recognition. PMID:27083263
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Amylose tris (phenylcarbamate) chiral stationary phase (ATPC-CSP) was prepared and used for optical resolution of clusters 1 and 2. n-Hexane/2-propanol ( 99/1; v/v) were found to be the most suitable mobile phase on ATPC-CSP.
Inoue, Yoshihisa
2004-01-01
Direct Asymmetric Photochemistry with Circularly Polarized Light, H. RauCoherent Laser Control of the Handedness of Chiral Molecules, P. Brumer and M. ShapiroMagnetochiral Anisotropy in Asymmetric Photochemistry, G.L.J.A.RikkenEnantiodifferentiating Photosensitized Reactions, Y. InoueDiastereodifferentiating Photoreactions, N. Hoffmann and J.-P. PeteChirality in Photochromism, Y. Yokoyama and M. SaitoChiral Photochemistry with Transition Metal Complexes, S. Sakaki and T. HamadaTemplate-Induced Enantioselective Photochemical Reactions in S
Chiral-induced self-assembly sphere phase liquid crystal with fast switching time
Energy Technology Data Exchange (ETDEWEB)
Zhu, Ji-Liang; Ni, Shui-Bin; Ping Chen, Chao; Lu, Jian-Gang, E-mail: lujg@sjtu.edu.cn; Su, Yikai [National Engineering Lab for TFT-LCD Materials and Technologies, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wu, Dong-Qing [College of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Song, Xiao-Long; Chen, Chao-Yuan [The Jiangsu Hecheng Display Technology Co., Ltd., Nanjing 211300 (China); Shieh, Han-Ping D. [National Engineering Lab for TFT-LCD Materials and Technologies, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Photonics and Display Institute, National Chiao Tung University, Hsinchu 300, Taiwan (China)
2014-03-03
A fluid self-assembly sphere phase (SP) of liquid crystal induced by chiral dopant is observed in a narrow temperature range between isotropic and blue phase or between isotropic and chiral nematic phase. The SP consists of three-dimensional twist spheres (3-DTSs) and disclinations among 3-DTSs. The temperature range of the SP has been broadened to more than 85 °C by stabilizing the disclinations with amorphous polymer chains. The electro-optical switching time of the polymer-stabilized SP is demonstrated in sub-millisecond with a low switching electric field of 4.4 V μm{sup −1}, which is of promising applications in displays, 3-D tunable photonic crystals, and phase modulators.
Institute of Scientific and Technical Information of China (English)
Tomoyuki IKAI; Takayuki YAMADA
2016-01-01
Two novel polymers containing glucose units as the main-chain that only differ in terms of their regioregularity were synthesized to evaluate their chiral recognition abilities as chiral stationary phases( CSPs) for high performance liquid chromatography( HPLC). The regioregular polymer( poly-5)shows clear resolution ability for the racemate of cobalt(Ⅲ)acetylacetonate( Co( acac)3 ),whereas the corresponding regioirregular polymer(poly-3)does not show any chiral recognition for Co(acac)3. The regioregular polymer main-chain seems to play an important role not only in providing an efficient interaction with the racemate but also in expressing the chiral recognition ability as a CSP for HPLC.
Phase transitions in QCD and string theory
International Nuclear Information System (INIS)
We develop a unified effective field theory approach to the high-temperature phase transitions in QCD and string theory, incorporating winding modes (time-like Polyakov loops, vortices) as well as low-mass states (pseudoscalar mesons and glueballs, matter and dilaton supermultiplets). Anomalous scale invariance and the Z3 structure of the centre of SU(3) decree a first-order phase transition with simultaneous deconfinement and Polyakov loop condensation in QCD, whereas string vortex condensation is a second-order phase transition breaking a Z2 symmetry. We argue that vortex condensation is accompanied by a dilaton phase transition to a strong coupling regime, and comment on the possible role of soliton degrees of freedom in the high-temperature string phase. (orig.)
Dynamics of weak first order phase transitions
Gleiser, Marcello
1994-01-01
The dynamics of weak vs. strong first order phase transitions is investigated numerically for 2+1 dimensional scalar field models. It is argued that the change from a weak to a strong transition is itself a (second order) phase transition, with the order parameter being the equilibrium fractional population difference between the two phases at the critical temperature, and the control parameter being the coefficient of the cubic coupling in the free-energy density. The critical point is identified, and a power law controlling the relaxation dynamics at this point is obtained. Possible applications are briefly discussed.
Wu, Haibo; Wang, Dongqiang; Song, Guangjun; Ke, Yanxiong; Liang, Xinmiao
2014-04-01
By connecting a quinine or quinidine moiety to the peptoid chain through the C9-position carbamate group, we synthesized two new chiral selectors. After immobilizing them onto 3-mercaptopropyl-modified silica gel, two novel chiral stationary phases were prepared. With neutral, acid, and basic chiral compounds as analytes, we evaluated these two stationary phases and compared their chromatographic performance with chiral columns based on quinine tert-butyl carbamate and the previous peptoid. From the resolution of neutral and basic analytes under normal-phase mode, it was found that the new stationary phases exhibited much better enantioselectivity than the quinine tert-butyl carbamate column; the peptoid moiety played an important role in enantiorecognition, which controlled the elution orders of enantiomers; the assisting role of the cinchona alkaloid moieties was observed in some separations. Under acid polar organic phase mode, it was proved that cinchona alkaloid moieties introduced excellent enantiorecognitions for chiral acid compounds; in some separations, the peptoid moiety affected enantioseparations as well. Overall, chiral moieties with specific enantioselectivity were demonstrated to improve the performance of peptoid chiral stationary phase efficiently.
A Review of Salam Phase Transition in Protein Amino Acids Implication for Biomolecular Homochirality
Bai, F; Bai, Fan; Wang, Wenqing
2002-01-01
The origin of chirality, closely related to the evolution of life on the earth, has long been debated. In 1991, Abdus Salam suggested a novel approach to achieve biomolecular homochirality by a phase transition. In his subsequent publication, he predicted that this phase transition could eventually change D-amino acids to L-amino acids as C -H bond would break and H atom became a superconductive atom. Since many experiments denied the configuration change in amino acids, Salam hypothesis aroused suspicion. This paper is aimed to provide direct experimental evidence of a phase transition in alanine, valine single crystals but deny the configuration change of D- to L- enantiomers. New views on Salam phase transition are presented to revalidate its great importance in the origin of homochirality.
Alkylated and silylated β-cyclodextrin for gas chromatographic chiral stationary phases
Institute of Scientific and Technical Information of China (English)
唐课文; 易健民; 周春山
2002-01-01
Three new chiral stationary phases, 2,6-di-O-heptyl-3-O-trimethylsilyl-β-cyclodextrin(DHTBCD), 2,6-di-O-pentyl-3-O-trimethylsilyl-β-cyclodextrin (DPTBCD) and 2,6-di-O-butyl-3-O-trimethylsilyl-β-cyclodextrin (DBTBCD), were synthesized. Chromatographic properties such as column efficiency, thermal stability and column life span, were studied. The separations of enantiomers, such as ketone, esters, alcohols and olefines, were investigated on the alkylated and silylated β-cyclodextrin stationary phases. The influence of diluent on chiral separation was studied. The experimental results indicate that the stationary phases show good chromatographic properties in separating enantiomers. It is observed that inclusion complexation and hydrogen bonding interaction hardly play a role in separating enantiomers.
Finite-temperature phase transition of $N_{f}=3$ QCD with exact center symmetry
Misumi, Tatsuhiro; Itou, Etsuko
2015-01-01
For the $Z_{3}$-symmetric lattice QCD-like theory ($Z_3$-QCD), in which $SU(3)$ gauge theory is coupled with three fundamental Wilson quarks with flavor-dependent twisted boundary conditions, we calculate the expectation values of Polyakov loop and chiral condensate as functions of temperature on $16^3 \\times4$ and $20^3 \\times 4$ lattices with $m_{PS}/m_{V}=0.70$ fixed. We find the first-order phase transition with respect to the $Z_{3}$ center symmetry, where the Polyakov loop exhibits a hysteresis depending on the initial condition of thermalization process. We also show that the crossover behavior of chiral condensate around the critical temperature of the center transition and the manifestation of flavor symmetry breaking in the high-temperature phase.
Institute of Scientific and Technical Information of China (English)
Shi-jun Zheng; Zi-fa Li; Shu-yuan Zhang; Shao-kui Cao; Ming-sheng Tang; Qiu-jun Fen; Qi-feng Zhou
1999-01-01
A new series of chiral shish-kebab type liquid crystal block copolymers that form the smectic C(Sc*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC,DSC, TG, POM, X-ray diffraction and polarimeter. The copolymers 7 entered into liquid crystal phase when they were heated to their melting temperatures (Tm) and the copolymers 8 were in liquid crystal phase at room temperature with low viscosities. The smectic sanded texture or focal-conic texture were observed on POM.All the chiral block copolymers showed high optical activity. No racemization has happened. Temperaturevariable X-ray diffraction study together with POM and polarimetric analysis realized that they are chiral smectic C(Sc*) phase. Thus we offer in this report the first example of shish-kebab type liquid crystal block copolymers that form a chiral smectic C(Sc*) phase. The variation of melting and isotropization temperatures with molecular structure was also discussed.
Modelling of phase transitions: do it yourself
International Nuclear Information System (INIS)
We present the basics of a powerful contemporary statistical mechanical technique that can be used by students to explore first-order phase transitions by themselves and for models of their own construction. The technique is a generalization of the well-known Peierls argument and is applicable to various models on a lattice. We illustrate the technique with the help of two simple models that were recently used to simulate phase transitions on surfaces. (paper)
Desynchronization transitions in nonlinearly coupled phase oscillators
Burylko, Oleksandr; Pikovsky, Arkady
2011-01-01
We consider the nonlinear extension of the Kuramoto model of globally coupled phase oscillators where the phase shift in the coupling function depends on the order parameter. A bifurcation analysis of the transition from fully synchronous state to partial synchrony is performed. We demonstrate that for small ensembles it is typically mediated by stable cluster states, that disappear with creation of heteroclinic cycles, while for a larger number of oscillators a direct transition from full sy...
Thin film dynamics with surfactant phase transition
Köpf, M. H.; Gurevich, S. V.; Friedrich, R.
2009-01-01
A thin liquid film covered with an insoluble surfactant in the vicinity of a first-order phase transition is discussed. Within the lubrication approximation we derive two coupled equations to describe the height profile of the film and the surfactant density. Thermodynamics of the surfactant is incorporated via a Cahn-Hilliard type free-energy functional which can be chosen to describe a transition between two stable phases of different surfactant density. Within this model, a linear stabilit...
Phase transitions in two dimensions
International Nuclear Information System (INIS)
Although a two-dimensional solid with long-range translational order cannot existin the thermodynamic limit (N → ∞, V →∞, N/V finite) macroscopic samples of two-dimensional solids can exist. In this work, stability of the phase was determined by the usuar method of equating the pressure and chemical potential of the phases. (A.C.A.S.)
Molecular markers of phase transition in locusts
Institute of Scientific and Technical Information of China (English)
ARNOLD DE LOOF; ILSE CLAEYS; GERT SIMONET; PETER VERLEYEN; TIM VANDERSMISSEN; FILIP SAS; JURGEN HUYBRECHTS
2006-01-01
The changes accompanying the transition from the gregarious to the solitary phase state in locusts are so drastic that for a long time these phases were considered as distinct species. It was Boris Uvarov who introduced the concept of polyphenism. Decades of research revealed that phase transition implies changes in morphometry, the color of the cuticle, behavior and several aspects of physiology. In particular, in the recent decade, quite a number of molecular studies have been undertaken to uncover phase-related differences.They resulted in novel insights into the role of corazonin, neuroparsins, some protease inhibitors, phenylacetonitrile and so on. The advent of EST-databases of locusts (e.g. Kang et al., 2004) is a most encouraging novel development in physiological and behavioral locust research. Yet, the answer to the most intriguing question, namely whether or not there is a primordial molecular inducer of phase transition, is probably not within reach in the very near future.
Thermal phase mixing during first order phase transitions
Borrill, J; Borrill, Julian; Gleiser, Marcelo
1995-01-01
The dynamics of first order phase transitions are studied in the context of (3+1)-dimensional scalar field theories. Particular attention is paid to the question of quantifying the strength of the transition, and how `weak' and `strong' transitions have different dynamics. We propose a model with two available low temperature phases separated by an energy barrier so that one of them becomes metastable below the critical temperature T_c. The system is initially prepared in this phase and is coupled to a thermal bath. Investigating the system at its critical temperature, we find that `strong' transitions are characterized by the system remaining localized within its initial phase, while `weak' transitions are characterized by considerable phase mixing. Always at T_c, we argue that the two regimes are themselves separated by a (second order) phase transition, with an order parameter given by the fractional population difference between the two phases and a control parameter given by the strength of the scalar fi...
Two-Color QCD with Non-zero Chiral Chemical Potential
Braguta, V V; Ilgenfritz, E -M; Kotov, A Yu; Molochkov, A V; Muller-Preussker, M; Petersson, B
2015-01-01
The phase diagram of two-color QCD with non-zero chiral chemical potential is studied by means of lattice simulation. We focus on the influence of a chiral chemical potential on the confinement/deconfinement phase transition and the breaking/restoration of chiral symmetry. The simulation is carried out with dynamical staggered fermions without rooting. The dependences of the Polyakov loop, the chiral condensate and the corresponding susceptibilities on the chiral chemical potential and the temperature are presented. The critical temperature is observed to increase with increasing chiral chemical potential.
Two-color QCD with non-zero chiral chemical potential
Braguta, V. V.; Goy, V. A.; Ilgenfritz, E. M.; Kotov, A. Yu.; Molochkov, A. V.; Müller-Preussker, M.; Petersson, B.
2015-06-01
The phase diagram of two-color QCD with non-zero chiral chemical potential is studied by means of lattice simulation. We focus on the influence of a chiral chemical potential on the confinement/deconfinement phase transition and the breaking/restoration of chiral symmetry. The simulation is carried out with dynamical staggered fermions without rooting. The dependences of the Polyakov loop, the chiral condensate and the corresponding susceptibilities on the chiral chemical potential and the temperature are presented. The critical temperature is observed to increase with increasing chiral chemical potential.
The QCD chiral transition, $\\ua$ symmetry and the Dirac spectrum using domain wall fermions
Buchoff, Michael I; Christ, Norman H; Ding, H -T; Jung, Chulwoo; Karsch, F; Mawhinney, R D; Mukherjee, Swagato; Petreczky, P; Renfrew, Dwight; Schroeder, Chris; Vranas, P M; Yin, Hantao; Lin, Zhongjie
2013-01-01
We report on a study of the finite-temperature QCD transition region for temperatures between 139 and 196 MeV, with a pion mass of 200 MeV and two space-time volumes: $24^3\\times8$ and $32^3\\times8$, where the larger volume varies in linear size between 5.6 fm (at T=139 MeV) and 4.0 fm (at T=195 MeV). These results are compared with the results of an earlier calculation using the same action and quark masses but a smaller, $16^3\\times8$ volume. The chiral domain wall fermion formulation with a combined Iwasaki and dislocation suppressing determinant ratio gauge action are used. This lattice action accurately reproduces the $\\sua$ and $\\ua$ symmetries of the continuum. Results are reported for the chiral condensates, connected and disconnected susceptibilities and the Dirac eigenvalue spectrum. We find a pseudo-critical temperature, $T_c$, of approximately 165 MeV consistent with previous results and strong finite volume dependence below $T_c$. Clear evidence is seen for $\\ua$ symmetry breaking above $T_c$ whi...
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.
Magnetic phase transitions in layered intermetallic compounds
Mushnikov, N. V.; Gerasimov, E. G.; Rosenfeld, E. V.; Terent'ev, P. B.; Gaviko, V. S.
2012-10-01
Magnetic, magnetoelastic, and magnetotransport properties have been studied for the RMn2Si2 and RMn6Sn6 (R is a rare earth metal) intermetallic compounds with natural layered structure. The compounds exhibit wide variety of magnetic structures and magnetic phase transitions. Substitution of different R atoms allows us to modify the interatomic distances and interlayer exchange interactions thus providing the transition from antiferromagnetic to ferromagnetic state. Near the boundary of this transition the magnetic structures are very sensitive to the external field, temperature and pressure. The field-induced transitions are accompanied by considerable change in the sample size and resistivity. It has been shown that various magnetic structures and magnetic phase transitions observed in the layered compounds arise as a result of competition of the Mn-Mn and Mn-R exchange interactions.
Jin, Kab Bong; Kim, Hee Eun; Hyun, Myung Ho
2014-05-01
Mexiletine, an effective class IB antiarrhythmic agent, and its analogs were resolved on three different crown ether-based chiral stationary phases (CSPs), one (CSP 1) of which is based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid and the other two (CSP 2 and CSP 3) are based on (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6. Mexiletine was resolved with a resolution (R(S)) of greater than 1.00 on CSP 1 and CSP 3 containing residual silanol group-protecting n-octyl groups on the silica surface, but with a resolution (R(S)) of less than 1.00 on CSP 2. The chromatographic behaviors for the resolution of mexiletine analogs containing a substituted phenyl group at the chiral center on the three CSPs were quite dependent on the phenoxy group of analytes. Namely, mexiletine analogs containing 2,6-dimethylphenoxy, 3,4-dimethylphenoxy, 3-methylphenoxy, 4-methylphenoxy, and a simple phenoxy group were resolved very well on the three CSPs even though the chiral recognition efficiencies vary with the CSPs. However, mexiletine analogs containing 2-methylphenoxy group were not resolved at all or only slightly resolved. Among the three CSPs, CSP 3 was found to show the highest chiral recognition efficiencies for the resolution of mexiletine and its analogs, especially in terms of resolution (R(S)). PMID:24677299
Comparative Optical Separation of Racemic Ibuprofen by Using Chiral Stationary Phase
Institute of Scientific and Technical Information of China (English)
Dalkeun; PARK; Joong; Kee; LEE; 等
2002-01-01
Ibprofen is widely used as a non-steroidal anti-inflammatory drug and poduced as racemic mixture.Its pharmacological activity resides only is S-(+)-enantiomer,and R-(-)-enantiomer is not only inactive but also has many side effects.Thus it is necessary to separate Renantiomer from racemic ibuprofen.We studied optical separation of racemic Ibuprofen with chiral high performance liquid chromatography(HPLC).,Out of three different chiral stationary phases,which were selected on the basis of structure and availability,two were found to be effective.There was optimum eluent composition for each stationary phase for good resolution in optical separation.Resolution decreased with increase of eluent flow rate,but effect of injection volume on resolution was insignificant at high eluent flow rate.
The Structural Phase Transition in Solid DCN
DEFF Research Database (Denmark)
Dietrich, O. W.; Mackenzie, Gordon A.; Pawley, G. S.
1975-01-01
Neutron scattering measurements on deuterated hydrogen cyanide have shown that the structural phase change from a tetragonal to an orthorhombic form at 160K is a first-order transition. A transverse acoustic phonon mode, which has the symmetry of the phase change, was observed at very low energie...
Numerical Study of Phase Transition in Thermoviscoelasticity
Institute of Scientific and Technical Information of China (English)
ShaoqingTANG
1997-01-01
We study the spatially periodic problem of thermoviscoelasticity with nonmonotone structure relations.By pseudo-spectral method.we demosnstrate numerically phase transitions for certain symmetric initial data.Without symmetry,the simulations show that a translation occurs for the phase boundary.
Classifying the Phases of Gauge Theories by Spectral Density of Probing Chiral Quarks
Alexandru, Andrei
2015-01-01
We describe our recent proposal that distinct phases of gauge theories with fundamental quarks translate into specific types of low-energy behavior in Dirac spectral density. The resulting scenario is built around new evidence substantiating the existence of a phase characterized by bimodal (anomalous) density, and corresponding to deconfined dynamics with broken valence chiral symmetry. We argue that such anomalous phase occurs quite generically in these theories, including in "real world" QCD above the crossover temperature, and in zero-temperature systems with many light flavors.
Phase Transition in the Simplest Plasma Model
Iosilevskiy, Igor
2009-01-01
We have investigated the phase transition of the gas-liquid type, with an upper critical point, in a variant of the One Component Plasma model (OCP) that has a uniform but compressible compensating background. We have calculated the parameters of the critical and triple points, spinodals, and two-phase coexistence curves (binodals). We have analyzed the connection of this simplest plasma phase transition with anomalies in the spatial charge profiles of equilibrium non-uniform plasma in the local-density approximations of Thomas-Fermi or Poisson-Boltzmann-type.
End point of the electroweak phase transition
Csikor, Ferenc; Heitger, J; Aoki, Y; Ukawa, A
1999-01-01
We study the hot electroweak phase transition (EWPT) by 4-dimensional lattice simulations on lattices with symmetric and asymmetric lattice spacings and give the phase diagram. A continuum extrapolation is done. We find first order phase transition for Higgs-boson masses $m_H<66.5 \\pm 1.4$ GeV. Above this end point a rapid cross-over occurs. Our result agrees with that of the dimensional reduction approach. It also indicates that the fermionic sector of the Standard Model (SM) may be included perturbatively. We get for the SM end point $72.4 the SM.
sprotocols
2015-01-01
Authors: Ren-Qi Wang, Teng-Teng Ong, Ke Huang, Weihua Tang & Siu-Choon Ng ### Abstract We described a facile and effective protocol wherein radical copolymerization is employed to covalently bond cationic β-cyclodextrin (β-CD) onto silica particles with extended linkage, resulting in a chiral stationary phase (IMPCSP) that can be used for the enantioseparation of racemic drugs in both high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). Start...
Thermochromic phase transitions in two aromatic tetrachlorocuprates
Mostafa, M. Fareed; Abdel-Kader, M. M.; Arafat, S. S.; Kandeel, E. M.
1991-06-01
Bis(para-toluidinium)2 tetrachlorocuprate and bis(para-chloroanilinium)2 tetrachlorocuprate crystallize in a perovskite-related layer structure. The former crystallizes in an orthorhombic unit cell with a = 6.911 Å, b = 7.052 Å and c = 33.182 Å. It undergoes a thermochromic first order phase transition from a yellow low temperature phase to a dark orange high temperature phase at T = 300 ± 3K with a 10° thermal hysteresis. The latter compound undergoes two thermochromic transitions expressed by the relation. Orange Phase (I) rightleftarrows294 K Yellow Phase (II) rightleftarrows214K Green Phase (III). Both compounds are ferromagnetic at low temperture with exchange interactions J/k = 17.5° and 20° for the two compounds respectively.
Phase transitions and entropies for synchronizing oscillators.
Bier, Martin; Lisowski, Bartosz; Gudowska-Nowak, Ewa
2016-01-01
We study a generic model of coupled oscillators. In the model there is competition between phase synchronization and diffusive effects. For a model with a finite number of states we derive how a phase transition occurs when the coupling parameter is varied. The phase transition is characterized by a symmetry breaking and a discontinuity in the first derivative of the order parameter. We quantitatively account for how the synchronized pulse is a low-entropy structure that facilitates the production of more entropy by the system as a whole. For a model with many states we apply a continuum approximation and derive a potential Burgers' equation for a propagating pulse. No phase transition occurs in that case. However, positive entropy production by diffusive effects still exceeds negative entropy production by the shock formation. PMID:26871059
Quantum trajectory phase transitions in the micromaser.
Garrahan, Juan P; Armour, Andrew D; Lesanovsky, Igor
2011-08-01
We study the dynamics of the single-atom maser, or micromaser, by means of the recently introduced method of thermodynamics of quantum jump trajectories. We find that the dynamics of the micromaser displays multiple space-time phase transitions, i.e., phase transitions in ensembles of quantum jump trajectories. This rich dynamical phase structure becomes apparent when trajectories are classified by dynamical observables that quantify dynamical activity, such as the number of atoms that have changed state while traversing the cavity. The space-time transitions can be either first order or continuous, and are controlled not just by standard parameters of the micromaser but also by nonequilibrium "counting" fields. We discuss how the dynamical phase behavior relates to the better known stationary-state properties of the micromaser. PMID:21928957
Phase Transition Induced Fission in Lipid Vesicles
Leirer, C; Myles, V M; Schneider, M F
2010-01-01
In this work we demonstrate how the first order phase transition in giant unilamellar vesicles (GUVs) can function as a trigger for membrane fission. When driven through their gel-fluid phase transition GUVs exhibit budding or pearl formation. These buds remain connected to the mother vesicle presumably by a small neck. Cooling these vesicles from the fluid phase (T>Tm) through the phase transition into the gel state (T
Closure Phase Signatures of Planet Transit Events
Van Belle, G T
2008-01-01
Planet transit events present as attractive targets for the ultra-high-resolution capabilities afforded by optical interferometers. Herein is presented an evaluation of the possibility of detection of such events through measurement of high-precision closure phases with the MIRC instrument on the CHARA Array. Recovery of the transit position angle upon the sky appears readily achievable with the existing capabilities of the instrument, along with characterization of other system parameters, such as stellar radius, planet radius, and other parameters of the transit event. This technique is the only one presently available that can provide a transiting planet's orbital plane position angle, and can directly determine the planet's radius independent of any outside observations, appearing able to improve substantially upon other determinations of that radius. Additional directly observed parameters - also not dependent upon transit photometry or spectroscopy - include impact parameter, transit ingress time, trans...
Geometric phase and o-mode blue shift in a chiral anisotropic medium inside a Fabry-P\\'erot cavity
Timofeev, I V; Sutormin, V S; Myslivets, S A; Arkhipkin, V G; Vetrov, S Ya; Lee, W; Zyryanov, V Ya
2015-01-01
Anomalous spectral shift of transmission peaks is observed in a Fabry--P\\'erot cavity filled with a chiral anisotropic medium. The effective refractive index value resides out of the interval between the ordinary and the extraordinary refractive indices. The spectral shift is explained by contribution of a geometric phase. The problem is solved analytically using the approximate Jones matrix method, numerically using the accurate Berreman method and geometrically using the generalized Mauguin--Poincar\\'e rolling cone method. The $o$-mode blue shift is measured for a 4-methoxybenzylidene-4'-$n$-butylaniline twisted--nematic layer inside the Fabry--P\\'erot cavity. The twist is electrically induced due to the homeoplanar--twisted configuration transition in an ionic-surfactant-doped liquid crystal layer. Experimental evidence confirms the validity of the theoretical model.
Phase Transitions in Operational Risk
Kartik Anand; Reimer K\\"uhn
2006-01-01
In this paper we explore the functional correlation approach to operational risk. We consider networks with heterogeneous a-priori conditional and unconditional failure probability. In the limit of sparse connectivity, self-consistent expressions for the dynamical evolution of order parameters are obtained. Under equilibrium conditions, expressions for the stationary states are also obtained. The consequences of the analytical theory developed are analyzed using phase diagrams. We find co-exi...
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Using four β-cyclodextrin derivatives, 2,6-di-O-benzyl-3-O-heptanonyl-β-CD, 2,6-di-O-benzyl-3-O-octanonyl-β-CD, 2,3-di-O-benzyl-6-O-heptanonyl-β-CD, and 2,3-di-O-benzy1-6-O-octanonyl-β-CD, as chiral stationary phases of capillary gas chromatography (CGC), the enantiomers of Sharpless epoxides were well separated. The enantiomer excess values (e.e.%) of some chiral Sharpless epoxides were also determined successfully using these CDs.
B→A transitions in the light-cone QCD sum rules with the chiral current
Institute of Scientific and Technical Information of China (English)
SUN Yan-Jun; WANG Zhi-Gang; HUANG Tao
2012-01-01
In this article,we calculate the form-factors of the transitions B → a1(1260),b1(1235) in the leading-order approximation using the light-cone QCD sum rules.In calculations,we choose the chiral current to interpolate the B-meson,which has the outstanding advantage that the twist-3 light-cone distribution amplitudes of the axial-vector mesons make no contributions,and the resulting sum rules for the form-factors suffer from far fewer uncertainties.Then we study the semi-leptonic decays B → a1(1260)l(v1),b1(1235)l(v1) (l =e,μ,Τ),and make predictions for the differential decay widths and decay widths,which can be compared with the experimental data in the coming future.
\\pi N transition distribution amplitudes: their symmetries and constraints from chiral dynamics
Pire, Bernard; Szymanowski, Lech
2011-01-01
Baryon to meson Transition Distribution Amplitudes (TDAs) extend the concept of generalized parton distributions. Baryon to meson TDAs appear as building blocks in the colinear factorized description of amplitudes for a class of hard exclusive reactions, prominent examples of which being hard exclusive meson electroproduction off a nucleon in the backward region and baryon-antibaryon annihilation into a meson and a lepton pair. We study general properties of these objects following from the underlying symmetries of QCD. In particular, the Lorentz symmetry results in the polynomiality property of the Mellin moments in longitudinal momentum fractions. We present a detailed account of isotopic and permutation symmetry properties of nucleon to pion (\\pi N) TDAs. This restricts the number of independent leading twist \\pi N TDAs to eight functions providing description of all isotopic channels. Using chiral symmetry and the crossing relation between \\pi N TDAs and \\pi N generalized distribution amplitudes we establ...
PT phase transition in multidimensional quantum systems
Bender, Carl M
2012-01-01
Non-Hermitian PT-symmetric quantum-mechanical Hamiltonians generally exhibit a phase transition that separates two parametric regions, (i) a region of unbroken PT symmetry in which the eigenvalues are all real, and (ii) a region of broken PT symmetry in which some of the eigenvalues are complex. This transition has recently been observed experimentally in a variety of physical systems. Until now, theoretical studies of the PT phase transition have generally been limited to one-dimensional models. Here, four nontrivial coupled PT-symmetric Hamiltonians, $H=p^2/2+x^2/2+q^2/2+y^2/2+igx^2y$, $H=p^2/2+x^2/2+q^2/2+y^2+igx^2y$, $H=p^2/2+x^2/2+q^2/2+y^2/2+r^2/2+z^2/2+igxyz$, and $H=p^2/2+x^2/2+q^2/2+y^2+r^2/2+3z^2/2+igxyz$ are examined. Based on extensive numerical studies, this paper conjectures that all four models exhibit a phase transition. The transitions are found to occur at $g\\approx 0.1$, $g\\approx 0.04$, $g\\approx 0.1$, and $g\\approx 0.05$. These results suggest that the PT phase transition is a robust phen...
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
This paper presents a new chiral separation technology: two-phase (O/W) recognition chiral extraction. Distribution behavior of α-cyclohexyl-mandelic acid enantiomers was studied in the extraction system with D(L)-isobutyl tartrate in 1,2-dichloroethane organic phase and β-CD derivatives in aqueous phase, and the influence of the kind and concentration of extractant and pH on extraction performance was investigated. The experimental results indicate that two-phase (O/W) recognition chiral extraction is of strong chiral separation ability. HP-β-CD, HE-β-CD and Me-β-CD have higher recognition ability for S-CHMA than that for R-CHMA, among which HP-β-CD has the strongest ability; whereas, D-isobutyl tartrate has reversed recognition ability for them. In the extraction system containing HP-β-CD and D-isobutyl tartrate, e.e.% of S-CHMA in aqueous phase reached 27.6% by one stage extraction, and the distribution ratio for R-CHMA(kR) and for S-CHMA(kS) and separation factor (α) are 2.44, 0.89 and 2.49, respectively. Meanwhile, pH and concentration of extractant have great effects on chiral separation ability. Two-phase (O/W) recognition chiral extraction has great significance for preparative separation of racemic compounds.
Gu, Zhigang
2014-06-17
Oriented circular dichroism (OCD) is explored and successfully applied to investigate chiral surface-anchored metal-organic frameworks (SURMOFs) based on camphoric acid (D- and Lcam) with the composition [Cu2(Dcam) 2x(Lcam)2-2x(dabco)]n (dabco=1,4-diazabicyclo- [2.2.2]-octane). The three-dimensional chiral SURMOFs with high-quality orientation were grown on quartz glass plates by using a layer-by-layer liquid-phase epitaxy method. The growth orientation, as determined by X-ray diffraction (XRD), could be switched between the [001] and [110] direction by using either OH- or COOH-terminated substrates. These SURMOFs were characterized by using OCD, which confirmed the ratio as well as the orientation of the enantiomeric linker molecules. Theoretical computations demonstrate that the OCD band intensities of the enantiopure [Cu2(Dcam)2(dabco)] n grown in different orientations are a direct result of the anisotropic nature of the chiral SURMOFs. Finally, the enantiopure [Cu 2(Dcam)2(dabco)]n and [Cu2(Lcam) 2(dabco)]n SURMOFs were loaded with the two chiral forms of ethyl lactate [(+)-ethyl-D-lactate and (-)-ethyl-L-lactate)]. An enantioselective enrichment of >60 % was observed by OCD when the chiral host scaffold was loaded from the racemic mixture. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Large N phase transitions in supersymmetric Chern-Simons theory with massive matter
International Nuclear Information System (INIS)
We study three-dimensional N=2U(N) Chern-Simons theory on S3 coupled to 2Nf chiral multiplets deformed by mass terms. The partition function localizes to a matrix integral, which can be exactly computed in the large N limit. In a specific decompactification limit, the theory exhibits quantum (third-order) phase transitions at finite critical values of the coupling. The theory presents three phases when 0
Tang, Sheng; Bin, Qin; Chen, Wei; Bai, Zheng-Wu; Huang, Shao-Hua
2016-04-01
A series of chitosan bis(methylphenylcarbamate)-(isobutyrylamide) derivatives were synthesized by carbamylating chitosan isobutyrylamide with different methylphenyl isocyanates. Then the prepared chitosan derivatives were coated onto 3-aminopropyl silica particles, resulting in a series of new chiral stationary phases (CSPs) for high-performance liquid chromatography. It was observed that the chiral recognition abilities of these coated-type CSPs depended very much on the substituents on the phenyl moieties of the chitosan derivatives, the eluent composition, as well as the structure of racemates. As a typical example, the eluent tolerance of the prepared CSP with the best enantioseparation ability was investigated in detail, and the results revealed that the CSP exhibited extraordinary solvent tolerance and could still work without significant loss in enantioseparation capability after being flushed with chloroform (100%), ethyl acetate (100%) and even THF/n-hexane (70/30, v/v), while the traditional coated-type CSPs based on the cellulose and amylose derivatives, such as cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) and amylose tris(3,5-dimethylphenylcarbamate) (ADMPC), might be dissolved or highly swollen in these eluents. Therefore, the application of the resultant CSPs could address the problem of the dissolution and high swelling of traditional coated-type CSPs in some unusual eluents, broadening the possibility of eluent choice. In addition, a comparison of the prepared CSPs with the well known CDMPC- and ADMPC- based CSPs concerning the chiral recognition ability was also made. Separation performances achieved on the as-prepared CSPs in different eluents were found to be even superior to CDMPC- and ADMPC-based CSPs for the tested chiral compounds. In summary, we could safely draw the conclusion that the CSPs derived from chitosan isobutyrylamide derivatives were capable of excellent chiral recognition ability, and meanwhile possessed satisfactory
QCD Phase-transition and chemical freezeout in nonzero magnetic field at NICA
Tawfik, Abdel Nasser
2016-01-01
Because of relativistic off-center motion of the charged spectators and the local momentum-imbalance experienced by the participants, a huge magnetic field is likely generated in high-energy collisions. The influence of such short-lived magnetic field on the QCD phase-transition(s) shall be analysed. From Polyakov linear-sigma model, we study the chiral phase-transition and the magnetic response and susceptibility in dependence on temperature, density and magnetic field strength. The systematic measurements of the phase-transition characterizing signals, such as the fluctuations, the dynamical correlations and the in-medium modifications of rho-meson, for instance, in different interacting systems and collision centralities are conjectured to reveal an almost complete description for the QCD phase-structure and the chemical freezeout. We limit the discussion to NICA energies.
Synthesis of chiral polyaniline films via chemical vapor phase polymerization
DEFF Research Database (Denmark)
Chen, J.; Winther-Jensen, B.; Pornputtkul, Y.;
2006-01-01
Electrically and optically active polyaniline films doped with (1)-(-)-10- camphorsulfonic acid were successfully deposited on nonconductive substrates via chemical vapor phase polymerization. The above polyaniline/ R- camphorsulfonate films were characterized by electrochemical and physical...... and Raman spectrum, but also exhibited optical activity corresponding to the polymer chains as observed by circular dichroism spectra. (c) 2005 The Electrochemical Society....
Matsumura, Masanori; Katayama, Norihisa
2016-07-01
Study on molecular orientation behavior of highly twisted chiral nematic liquid crystals (N∗LCs) expressing blue phases (BPs) is important for developing new devices. This study examines the change of molecular orientation of N∗LCs due to the presence of BPs. Polarized microscopic FT-IR spectroscopy was used to study the in- and out-of-plane molecular orientations of N∗LCs that undergo a phase transition involving BPs. The band intensity ratio of CN to CH2 stretching modes (CN/CH2) in the IR spectra was used to determine the orientation of N∗LC molecules. The measured spectra indicated that the helical axis of N∗LC molecules was perpendicular to the substrate before heating and inclined on the substrate after cooling the sample which has phase transition from BP I to chiral nematic (N∗). The N∗LC molecule in the cell of rubbed orientation film exhibited the in-plane anisotropy after a heating-cooling ramp only in samples that passed through BP I. These results indicate that the changes of molecular orientation of N∗LC by phase transition are affected by BP I.
Phase transitions in warm, asymmetric nuclear matter
International Nuclear Information System (INIS)
A relativistic mean-field model of nuclear matter with arbitrary proton fraction is studied at finite temperature. An analysis is performed of the liquid-gas phase transition in a system with two conserved charges (baryon number and isospin) using the stability conditions on the free energy, the conservation laws, and Gibbs' criteria for phase equilibrium. For a binary system with two phases, the coexistence surface (binodal) is two dimensional. The Maxwell construction through the phase-separation region is discussed, and it is shown that the stable configuration can be determined uniquely at every density. Moreover, because of the greater dimensionality of the binodal surface, the liquid-gas phase transition is continuous (second order by Ehrenfest's definition), rather than discontinuous (first order), as in familiar one-component systems. Using a mean-field equation of state calibrated to the properties of nuclear matter and finite nuclei, various phase-separation scenarios are considered. The model is then applied to the liquid-gas phase transition that may occur in the warm, dilute matter produced in energetic heavy-ion collisions. In asymmetric matter, instabilities that produce a liquid-gas phase separation arise from fluctuations in the proton concentration (chemical instability), rather than from fluctuations in the baryon density (mechanical instability)
Formation of droplets with high baryon density at the QCD phase transition in expanding matter
Energy Technology Data Exchange (ETDEWEB)
Herold, Christoph [School of Physics, Suranaree University of Technology, 111 University Avenue, Nakhon Ratchasima 30000 (Thailand); Institut für Theoretische Physik, Goethe-Universität, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies (FIAS), Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Nahrgang, Marlene [Frankfurt Institute for Advanced Studies (FIAS), Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Department of Physics, Duke University, Durham, NC 27708 (United States); Mishustin, Igor [Frankfurt Institute for Advanced Studies (FIAS), Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Kurchatov Institute, National Research Center, 123182 Moscow (Russian Federation); Bleicher, Marcus [Institut für Theoretische Physik, Goethe-Universität, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies (FIAS), Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany)
2014-05-15
We consider the (3+1)-dimensional expansion and cooling of the chirally-restored and deconfined matter at finite net-baryon densities as expected in heavy-ion collisions at moderate energies. In our approach, we consider chiral fields and the Polyakov loop as dynamical variables coupled to a medium represented by a quark–antiquark fluid. The interaction between the fields and the fluid leads to dissipation and noise, which in turn affect the field fluctuations. We demonstrate how inhomogeneities in the net-baryon density may form during an evolution through the spinodal region of the first-order phase transition. For comparison, the dynamics of transition through the crossover and critical end point is also considered.
Critical behavior in the electroweak phase transition
Gleiser, Marcello
1993-01-01
We examine the behavior of the standard-model electroweak phase transition in the early Universe. We argue that close to the critical temperature it is possible to estimate the {\\it effective} infrared corrections to the 1-loop potential using well known $\\varepsilon$-expansion results from the theory of critical phenomena in 3 spatial dimensions. The theory with the $\\varepsilon$-corrected potential exhibits much larger fluctuations in the spatial correlations of the order parameter, considerably weakening the strength of the transition.
The phase structure of a chirally invariant lattice Higgs-Yukawa model. Numerical simulations
International Nuclear Information System (INIS)
The phase diagram of a chirally invariant lattice Higgs-Yukawa model is explored by means of numerical simulations. The results revealing a rich phase structure are compared to analytical large Nf calculations which we performed earlier. The analytical and numerical results are in excellent agreement at large values of Nf. In the opposite case the large Nf computation still gives a good qualitative description of the phase diagram. In particular we find numerical evidence for the predicted ferrimagnetic phase at intermediate values of the Yukawa coupling constant and for the symmetric phase at strong Yukawa couplings. Emphasis is put on the finite size effects which can hide the existence of the latter symmetric phase. (orig.)
Taschwer, Magdalena; Seidl, Yvonne; Mohr, Stefan; Schmid, Martin G
2014-08-01
In the last years the identification of new legal and illegal highs has become a huge challenge for the police and prosecution authorities. In an analytical context, only a few analytical methods are available to identify these new substances. Moreover, many of these recreational drugs are chiral and it is supposed that the enantiomers differ in their pharmacological potency. Since nonenantioselective synthesis is easier and cheaper, they are mainly sold as racemic mixtures. The goal of this research work was to develop an inexpensive method for the chiral separation of cathinones and amphetamines. This should help to discover if the substances are sold as racemic mixtures and give further information about their quality as well as their origin. Chiral separation of a set of 6 amphetamine and 25 cathinone derivatives, mainly purchased from various Internet shops, is presented. A LiChrospher 100 RP-18e, 250 x 4 mm, 5 µm served as the stationary phase. The chiral mobile phase consisted of methanol, water, and sulfated ß-cyclodextrin. Measurements were performed under isocratic conditions in reversed phase mode using UV detection. Four model compounds of the two substance classes were used to optimize the mobile phase. Under final conditions (methanol:water 2.5:97.5 + 2% sulfated ß-cyclodextrin) enantiomers of amphetamine and five derivatives were baseline separated within 23 min. In all, 17 cathinones were completely or partially chirally separated. However, as only 3 of 25 cathinones were baseline resolved, the application of this method is limited for cathinone analogs. Additionally, the results were compared with an RP-8e column.
Quantum phase transitions with dynamical flavors
Bea, Yago; Ramallo, Alfonso V
2016-01-01
We study the properties of a D6-brane probe in the ABJM background with smeared massless dynamical quarks in the Veneziano limit. Working at zero temperature and non-vanishing charge density, we show that the system undergoes a quantum phase transition in which the topology of the brane embedding changes from a black hole to a Minkowski embedding. In the unflavored background the phase transition is of second order and takes place when the charge density vanishes. We determine the corresponding critical exponents and show that the scaling behavior near the quantum critical point has multiplicative logarithmic corrections. In the background with dynamical quarks the phase transition is of first order and occurs at non-zero charge density. In this case we compute the discontinuity of several physical quantities as functions of the number $N_f$ of unquenched quarks of the background.
The diamagnetic phase transition in Magnetars
Wang, Zhaojun; Zhu, Chunhua; Wu, Baoshan
2016-01-01
Neutron stars are ideal astrophysical laboratories for testing theories of the de Haas-van Alphen (dHvA) effect and diamagnetic phase transition which is associated with magnetic domain formation. The "magnetic interaction" between delocalized magnetic moments of electrons (the Shoenberg effect), can result in an effect of the diamagnetic phase transition into domains of alternating magnetization (Condon's domains). Associated with the domain formation are prominent magnetic field oscillation and anisotropic magnetic stress which may be large enough to fracture the crust of magnetar with a super-strong field. Even if the fracture is impossible as in "low-field" magnetar, the depinning phase transition of domain wall motion driven by low field rate (mainly due to the Hall effect) in the randomly perturbed crust can result in a catastrophically variation of magnetic field. This intermittent motion, similar to the avalanche process, makes the Hall effect be dissipative. These qualitative consequences about magne...
Non-equilibrium dynamics and phase transitions
Janik, Romuald A; Soltanpanahi, Hesam
2015-01-01
We study the poles of the retarded Green's functions of strongly coupled field theories exhibiting a variety of phase structures from a crossover up to a first order phase transition. These theories are modeled by a dual gravitational description. The poles of the holographic Green's functions appear at the frequencies of the quasinormal modes of the dual black hole background. We establish that near the transition, in all cases considered, the applicability of a hydrodynamic description breaks down already at lower momenta than in the conformal case. We establish the appearance of the spinodal region in the case of the first order phase transition at temperatures for which the speed of sound squared is negative. An estimate of the preferential scale attained by the unstable modes is also given. We additionally observe a novel diffusive regime for sound modes for a range of wavelengths.
Xu, Li; Miao, Xinrui; Cui, Lihua; Liu, Pei; Chen, Xiaofeng; Deng, Wenli
2015-07-01
Understanding the formation and structural transition of the two-dimensional chirality of self-assembly is a subject which still gains significant interest in surface or interface chirality studies. Here, we present the solvent-induced chiral structural transition of a 2-hydroxy-7-pentadecyloxy-9-fluorenone (HPF) molecules' self-assembled adlayer through coassembly with achiral aliphatic solvents under different concentrations. Polymorphic chiral patterns are obtained at low concentrations of aliphatic solvents with different chain lengths. The HPF molecules form coassembled structures with these solvents through van der Waals interactions. At the same time, at high concentrations, HPF molecules uniformly form a nonchiral multimer structure without coadsorbed aliphatic solvent molecules. What is interesting is that these structures under different concentrations will finally change into a zigzag structure, which is the thermodynamically most stable configuration. Especially when using n-hexadecane as the solvent, the adlayer shows perfect steric matching due to the close chain length of HPF and n-hexadecane, which can maximize the molecule-solvent interactions. Thus, HPF molecules in n-hexadecane exhibit the most diversiform configuration. The distinct concentration-dependence has proven that the solvent molecules can act as a coadsorbed component through van der Waals interactions rather than simply a dispersant and further result in the probability and stability of chiral self-assembled monolayers by subtle tuning of the solvent-molecule and solvent-substrate interactions. This result provides a simple and alternative strategy to construct the 2D chiral assembled monolayer.Understanding the formation and structural transition of the two-dimensional chirality of self-assembly is a subject which still gains significant interest in surface or interface chirality studies. Here, we present the solvent-induced chiral structural transition of a 2-hydroxy-7-pentadecyloxy
Engineering Cyclodextrin Clicked Chiral Stationary Phase for High-Efficiency Enantiomer Separation
Tang, Jian; Zhang, Shapopeng; Lin, Yuzhou; Zhou, Jie; Pang, Limin; Nie, Xuemei; Zhou, Baojing; Tang, Weihua
2015-08-01
The separation of racemic molecules is of crucial significance not only for fundamental research but also for technical application. Enantiomers remain challenging to be separated owing to their identical physical and chemical properties in achiral environments. Chromatographic techniques employing chiral stationary phases (CSPs) have been developed as powerful tools for the chiral analysis and preparation of pure enantiomers, most of which are of biological and pharmaceutical interests. Here we report our efforts in developing high-performance phenylcarbamated cyclodextrin (CD) clicked CSPs. Insights on the impact of CD functionalities in structure design are provided. High-efficiency enantioseparation of a range of aryl alcohols and flavanoids with resolution values (Rs) over 10 were demonstrated by per(3-chloro-4-methyl)phenylcarbamated CD clicked CSP. Comparison study and molecular simulations suggest the improved enantioselectivity was attributed to higher interactions energy difference between the complexes of enantiomers and CSPs with phenylcarbamated CD bearing 3-chloro and 4-methyl functionalities.
Some phase transition studies under shock waves
International Nuclear Information System (INIS)
Experimental studies on pressure-induced phase transitions are generally conducted using both static- and shock-loading techniques. Comparison of these results is interesting as the presence of shear and high strain rate under shock compression may alter the mechanism of a transition and also its onset pressure. Recently we have carried out an gas-gun experiments to study phase transitions in GeO2, Ti and Zr. In Ti and Zr, our objective has been to understand the causes of the reported scatter in the pressure of shock induced α -> ω transition (6.0 - 11.9 GPa). Our experiments on Zr show that the initial oxygen content of the sample has a large influence on the transition pressure. For example no α to ω transition is seen up to 11 GPa in Zr samples containing oxygen concentration above 1600 ppm. Unlike that in static experiments, the effect of shear is found to be small up to 9 GPa in inclined impact experiments in Ti. The microscopic nature of the α -> ω transition in Zr has also been examined using selected area electron diffraction measurements
Queueing phase transition: theory of translation
Romano, M. Carmen; Thiel, Marco; Stansfield, Ian; Grebogi, Celso
2009-01-01
We study the current of particles on a lattice, where to each site a different hopping probability has been associated and the particles can move only in one direction. We show that the queueing of the particles behind a slow site can lead to a first-order phase transition, and derive analytical expressions for the configuration of slow sites for this to happen. We apply this stochastic model to describe the translation of mRNAs. We show that the first-order phase transition, uncovered in thi...
Scaling Concepts in Describing Continuous Phase Transitions
Indian Academy of Sciences (India)
2016-10-01
Phase transitions, like the boiling of water upon increasingtemperature, are a part of everyday experience and are yet,upon closer inspection, unusual phenomena, and reveal a hostof fascinating features. Comprehending key aspects of phasetransitions has lead to the uncovering of new ways of describingmatter composed of large numbers of interacting elements,which form a dominant way of analysis in contemporarystatistical mechanics and much else. An introductorydiscussion is presented here of the concepts of scaling, universalityand renormalization, which forms the foundation ofthe study of continuous phase transitions, such as the spontaneousmagnetization of ferromagnetic substances.
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.
Phase Transition in Loop Quantum Gravity
Mäkelä, Jarmo
2016-01-01
We point out that with a specific counting of states loop quantum gravity implies that black holes perform a phase transition at a certain characteristic temperature $T_C$. In this phase transition the punctures of the spin network on the stretched horizon of the black hole jump, in effect, from the vacuum to the excited states. The characteristic temperature $T_C$ may be regarded as the lowest possible temperature of the hole. From the point of view of a distant observer at rest with respect...
Network traffic behaviour near phase transition point
Lawniczak, A. T.; Tang, X.
2006-03-01
We explore packet traffic dynamics in a data network model near phase transition point from free flow to congestion. The model of data network is an abstraction of the Network Layer of the OSI (Open Systems Interconnect) Reference Model of packet switching networks. The Network Layer is responsible for routing packets across the network from their sources to their destinations and for control of congestion in data networks. Using the model we investigate spatio-temporal packets traffic dynamics near the phase transition point for various network connection topologies, and static and adaptive routing algorithms. We present selected simulation results and analyze them.
Phase Transition in Loop Quantum Gravity
Mäkelä, Jarmo
2016-01-01
We point out that with a specific counting of states loop quantum gravity implies that black holes perform a phase transition at a certain characteristic temperature $T_C$. In this phase transition the punctures of the spin network on the stretched horizon of the black hole jump, in effect, from the vacuum to the excited states. The characteristic temperature $T_C$ may be regarded as the lowest possible temperature of the hole. From the point of view of a distant observer at rest with respect to the hole the characteristic temperature $T_C$ corresponds to the Hawking temperature of the hole.
Phase transition in loop quantum gravity
Mäkelä, Jarmo
2016-04-01
We point out that with a specific counting of states loop quantum gravity implies that black holes perform a phase transition at a certain characteristic temperature TC . In this phase transition the punctures of the spin network on the stretched horizon of the black hole jump, in effect, from the vacuum to the excited states. The characteristic temperature TC may be regarded as the lowest possible temperature of the hole. From the point of view of a distant observer at rest with respect to the hole, the characteristic temperature TC corresponds to the Hawking temperature of the hole.
Quantum phase transitions in antiferromagnets and superfluids
Sachdev, Subir; Vojta, Matthias
2000-05-01
We present a general introduction to the non-zero temperature dynamic and transport properties of low-dimensional systems near a quantum phase transition. Basic results are reviewed in the context of experiments on the spin-ladder compounds, insulating two-dimensional antiferromagnets, and double-layer quantum Hall systems. Recent large N computations on an extended t- J model (Phys. Rev. Lett. 83 (1999) 3916) motivate a global scenario of the quantum phases and transitions in the high-temperature superconductors, and connections are made to numerous experiments.
Wu, Lianming; Vogt, Frederick G
2012-10-01
Chirality has been of great interest in pharmaceutical and biological sciences. The capabilities of mass spectrometry (MS) for rapid analysis of complex mixtures have encouraged its exploration for gas-phase chiral differentiation. Although particular instances of successful discrimination between enantiomers have been reported over the past three decades, a general method of quantitative chiral analysis by MS has only been demonstrated recently. This review describes the current state of the chiral MS methods without chiral chromatographic separation, which fall into five main categories: (1) the kinetic method, (2) host-guest (H-G) diastereomeric adduct formation, (3) ion/molecule (equilibrium) reactions, (4) collision-induced dissociation (CID) of diastereomeric adducts, and (5) the emerging technique for gas-phase separation using ion mobility spectrometry (IMS). It emphasizes tandem mass spectrometry (MS/MS), which provides several unique analytical advantages for quantitative chiral analysis. These include intrinsically high sensitivity, molecular specificity, and tolerance to impurities as well as the simplicity and speed of the mass spectrometric measurements. Practical prospects and current challenges in quantitative chiral MS techniques for QbD (quality-by-design)-based pharmaceutical applications are also discussed. PMID:22579598
PHASE TRANSITION IN SEQUENCE UNIQUE RECONSTRUCTION
Institute of Scientific and Technical Information of China (English)
Li XIA; Chan ZHOU
2007-01-01
In this paper,sequence unique reconstruction refers to the property that a sequence is uniquely reconstructable from all its K-tuples.We propose and study the phase transition behavior of the probability P(K)of unique reconstruction with regard to tuple size K in random sequences (iid model).Based on Monte Carlo experiments,artificial proteins generated from iid model exhibit a phase transition when P(K)abruptly jumps from a low value phase(e.g.＜0.1)to a high value phase (e.g.＞0.9).With a generalization to any alphabet,we prove that for a random sequence of length L,as L is large enough,P(K)undergoes a sharp phase transition when P≤0.1015 where p=P(two random letters match).Besides,formulas are derived to estimate the transition points,which may be of practical use in sequencing DNA by hybridization.Concluded from our study,most proteins do not deviate greatly from random sequences in the sense of sequence unique reconstruction,while there are some "stubborn" proteins which only become uniquely reconstructable at a very large K and probably have biological implications.
Transition to turbulence in pipe flow as a phase transition
Vasudevan, Mukund; Hof, Björn
2015-11-01
In pipe flow, turbulence first arises in the form of localized turbulent patches called puffs. The flow undergoes a transition to sustained turbulence via spatio-temporal intermittency, with puffs splitting, decaying and merging in the background laminar flow. However, the due to mean advection of the puffs and the long timescales involved (~107 advective time units), it is not possible to study the transition in typical laboratory set-ups. So far, it has only been possible to indirectly estimate the critical point for the transition. Here, we exploit the stochastic memoryless nature of the puff decay and splitting processes to construct a pipe flow set-up, that is periodic in a statistical sense. It then becomes possible to study the flow for sufficiently long times and characterize the transition in detail. We present measurements of the turbulent fraction as a function of Reynolds number which in turn allows a direct estimate of the critical point. We present evidence that the transition has features of a phase transition of second order.
Liquid gas phase transition in hypernuclei
Mallik, S
2016-01-01
The fragmentation of excited hypernuclear system formed in heavy ion collisions has been described by the canonical thermodynamical model extended to three component systems. The multiplicity distribution of the fragments has been analyzed in detail and it has been observed that the hyperons have the tendency to get attached to the heavier fragments. Another important observation is the phase coexistence of the hyperons, a phenomenon which is linked to liquid gas phase transition in strange matter.
Relation Between Chiral Susceptibility and Solutions of Gap Equation in Nambu--Jona-Lasinio Model
Zhao, Y; Liu, Y; Yuan, W; Chang, Lei; Liu, Yu-xin; Yuan, Wei; Zhao, Yue
2006-01-01
We study the solutions of the gap equation, the thermodynamic potential and the chiral susceptibility in and beyond the chiral limit at finite chemical potential in the Nambu--Jona-Lasinio (NJL) model. We give an explicit relation between the chiral susceptibility and the thermodynamic potential in the NJL model. We find that the chiral susceptibility is a quantity being able to represent the furcation of the solutions of the gap equation and the concavo-convexity of the thermodynamic potential in NJL model. It indicates that the chiral susceptibility can identify the stable state and the possibility of the chiral phase transition in NJL model.
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...
Supersymmetric Kosterlitz-Thouless phase transition
International Nuclear Information System (INIS)
Supersymmetry is introduced in the Coulomb gas, namely the statistical theory for a set of interacting vortices and antivortices. The equivalence of this theory to the supersymmetric Sine-Gordon model is established. Mean-field considerations applied to this supersymmetric Coulomb gas lead to a phase transition of the kind described by Kosterlitz and Thouless. 12 references
QCD phase transition and primordial density perturbations
Ignatius, J; Schwarz, Dominik J.
2000-01-01
We analyze the effect of primordial density perturbations on the cosmic QCD phase transition. According to our results hadron bubbles nucleate at the cold perturbations. We call this mechanism inhomogeneous nucleation. We find the typical distance between bubble centers to be a few meters. This exceeds the estimates from homogeneous nucleation by two orders of magnitude. The resulting baryon inhomogeneities may affect primordial nucleosynthesis.
Hysteresis in the phase transition of chocolate
Ren, Ruilong; Lu, Qunfeng; Lin, Sihua; Dong, Xiaoyan; Fu, Hao; Wu, Shaoyi; Wu, Minghe; Teng, Baohua
2016-01-01
We designed an experiment to reproduce the hysteresis phenomenon of chocolate appearing in the heating and cooling process, and then established a model to relate the solidification degree to the order parameter. Based on the Landau-Devonshire theory, our model gave a description of the hysteresis phenomenon in chocolate, which lays the foundations for the study of the phase transition behavior of chocolate.
On Julia sets concerning phase transitions
Institute of Scientific and Technical Information of China (English)
QIAO; Jianyong(乔建永)
2003-01-01
The sets of the points corresponding to the phase transitions of the Potts model on the diamondhierarchical lattice for antiferromagnetic coupling are studied. These sets are the Julia sets of a family ofrational mappings. It is shown that they may be disconnected sets. Furthermore, the topological structures ofthese sets are described completely.
Passive Supporters of Terrorism and Phase Transitions
August, Friedrich; Delitzscher, Sascha; Hiller, Gerald; Krueger, Tyll
2010-01-01
We discuss some social contagion processes to describe the formation and spread of radical opinions. The dynamics of opinion spread involves local threshold processes as well as mean field effects. We calculate and observe phase transitions in the dynamical variables resulting in a rapidly increasing number of passive supporters. This strongly indicates that military solutions are inappropriate.
Black Hole Phase Transition in Massive Gravity
Ning, Shou-Li; Liu, Wen-Biao
2016-07-01
In massive gravity, some new phenomena of black hole phase transition are found. There are more than one critical points under appropriate parameter values and the Gibbs free energy near critical points also has some new properties. Moreover, the Maxwell equal area rule is also investigated and the coexistence curve of the black hole is given.
Vol. 3: Statistical Physics and Phase Transitions
International Nuclear Information System (INIS)
Problems of modern physics and the situation with physical research in Ukraine are considered. Programme of the conference includes scientific and general problems. Its proceedings are published in 6 volumes. The papers presented in this volume refer to statistical physics and phase transition theory
The transition to chaotic phase synchronization
DEFF Research Database (Denmark)
Mosekilde, E.; Laugesen, J. L.; Zhusubaliyev, Zh. T.
2012-01-01
The transition to chaotic phase synchronization for a periodically driven spiral-type chaotic oscillator is known to involve a dense set of saddle-node bifurcations. By following the synchronization transition through the cascade of period-doubling bifurcations in a forced Ro¨ssler system......, this paper describes how these saddle-node bifurcations arise and how their characteristic cyclic organisation develops. We identify the cycles that are involved in the various saddle-node bifurcations and describe how the formation of multi-layered resonance cycles in the synchronization domain is related...... varying arterial blood pressure. The paper finally discusses how an alternative transition to chaotic phase synchronization may occur in the mutual synchronization of two chaotically oscillating period-doubling systems....
Finite temperature field theory and phase transitions
International Nuclear Information System (INIS)
These lectures review phases and phase transitions of the Standard Model, with emphasis on those aspects which are amenable to a first principle study. Model calculations and theoretical idea of practical applicability are discussed as well. Contents: 1. Overview; 2. Field Theory at Finite Temperature and Density; 3. Critical Phenomena; 4. Electroweak Interactions at Finite Temperature; 5. Thermodynamics of Four Fermions models; 6. The Phases of QCD; 7. QCD at Finite Temperature, μB = 0; 8. QCD at Finite Temperature, μB ≠ 0. (author)
Phase transition to QGP matter : confined vs deconfined matter
Maire, Antonin
2015-01-01
Simplified phase diagram of the nuclear phase transition, from the regular hadronic matter to the QGP phase. The sketch is meant to describe the transition foreseen along the temperature axis, at low baryochemical potential, µB.
Phase transitions in Pareto optimal complex networks
Seoane, Luís F
2015-01-01
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 to different arrangements of the connections; but the need of drastic topological changes does not determine the presence, nor the nature of the phase transit...
Phase transitions in a lattice population model
International Nuclear Information System (INIS)
We introduce a model for a population on a lattice with diffusion and birth/death according to 2A→3A and A→Φ for a particle A. We find that the model displays a phase transition from an active to an absorbing state which is continuous in 1 + 1 dimensions and of first-order in higher dimensions in agreement with the mean field equation. For the (1 + 1)-dimensional case, we examine the critical exponents and a scaling function for the survival probability and show that it belongs to the universality class of directed percolation. In higher dimensions, we look at the first-order phase transition by plotting a histogram of the population density and use the presence of phase coexistence to find an accurate value for the critical point in 2 + 1 dimensions
Szabó, Zoltán-István; Szőcs, Levente; Horváth, Péter; Komjáti, Balázs; Nagy, József; Jánoska, Ádám; Muntean, Daniela-Lucia; Noszál, Béla; Tóth, Gergő
2016-08-01
A sensitive and validated liquid chromatography with mass spectrometry method was developed for the enantioseparation of the racemic mixture of pomalidomide, a novel, second-generation immunomodulatory drug, using β-cyclodextrin-bonded stationary phases. Four cyclodextrin columns (β-, hydroxypropyl-β-, carboxymethyl-β-, and sulfobutyl-β-cyclodextrin) were screened and the effects of eluent composition, flow rate, temperature, and organic modifier on enantioseparation were studied. Optimized parameters, offering baseline separation (resolution = 2.70 ± 0.02) were the following: β-cyclodextrin stationary phase, thermostatted at 15°C, and mobile phase consisting of methanol/0.1% acetic acid 10:90 v/v, delivered with 0.8 mL/min flow rate. For the optimized parameter at multiple reaction monitoring mode 274.1-201.0 transition with 20 eV collision energy and 100 V fragmentor voltage the limit of detection and limit of quantitation were 0.75 and 2.00 ng/mL, respectively. Since enantiopure standards were not available, elution order was determined upon comparison of the circular dichroism signals of the separated pomalidomide enantiomers with that of enantiopure thalidomide. The mechanisms underlying the chiral discrimination between the enantiomers were also investigated. Pomalidomide-β-cyclodextrin inclusion complex was characterized using nuclear magnetic resonance spectroscopy and molecular modeling. The thermodynamic aspects of chiral separation were also studied. PMID:27279456
Szabó, Zoltán-István; Szőcs, Levente; Horváth, Péter; Komjáti, Balázs; Nagy, József; Jánoska, Ádám; Muntean, Daniela-Lucia; Noszál, Béla; Tóth, Gergő
2016-08-01
A sensitive and validated liquid chromatography with mass spectrometry method was developed for the enantioseparation of the racemic mixture of pomalidomide, a novel, second-generation immunomodulatory drug, using β-cyclodextrin-bonded stationary phases. Four cyclodextrin columns (β-, hydroxypropyl-β-, carboxymethyl-β-, and sulfobutyl-β-cyclodextrin) were screened and the effects of eluent composition, flow rate, temperature, and organic modifier on enantioseparation were studied. Optimized parameters, offering baseline separation (resolution = 2.70 ± 0.02) were the following: β-cyclodextrin stationary phase, thermostatted at 15°C, and mobile phase consisting of methanol/0.1% acetic acid 10:90 v/v, delivered with 0.8 mL/min flow rate. For the optimized parameter at multiple reaction monitoring mode 274.1-201.0 transition with 20 eV collision energy and 100 V fragmentor voltage the limit of detection and limit of quantitation were 0.75 and 2.00 ng/mL, respectively. Since enantiopure standards were not available, elution order was determined upon comparison of the circular dichroism signals of the separated pomalidomide enantiomers with that of enantiopure thalidomide. The mechanisms underlying the chiral discrimination between the enantiomers were also investigated. Pomalidomide-β-cyclodextrin inclusion complex was characterized using nuclear magnetic resonance spectroscopy and molecular modeling. The thermodynamic aspects of chiral separation were also studied.
Chiral anomaly and the BaBar and Belle measurements of the γγ*-->π0 transition form factor
Pham, T. N.
2012-10-01
The recent BaBar measurements of the γγ*→π0 transition form factor show spectacular deviation from perturbative QCD prediction for large space-like Q2 up to 34GeV2. In this talk, I would like to discuss a recent work on the chiral anomaly effects in the γγ*→π0 transition form factor F(Q2) at large momentum squared Q2. Using PCAC and the Adler-Bell-Jackiw chiral anomaly triangle graph, we find that, F(Q2) at large Q2 behaves as (m2/Q2)×(ln(Q2/m2))2 and is in striking agreement with the BaBar data with m = 135MeV which also reproduces very well the CLEO data at lower Q2. The new Belle measurements could also be fitted with m = 120MeV.
The comfortable driving model revisited: Traffic phases and phase transitions
Knorr, Florian
2013-01-01
We study the spatiotemporal patterns resulting from different boundary conditions for a microscopic traffic model and contrast it with empirical results. By evaluating the time series of local measurements, the local traffic states are assigned to the different traffic phases of Kerner's three-phase traffic theory. For this classification we use the rule-based FOTO-method, which provides `hard' rules for this assignment. Using this approach, our analysis shows that the model is indeed able to reproduce three qualitatively different traffic phases: free flow (F), synchronized traffic (S), and wide moving jams (J). In addition, we investigate the likelihood of transitions between the three traffic phases. We show that a transition from free flow (F) to a wide moving jam (J) often involves an intermediate transition; first from free flow F to synchronized flow S and then from synchronized flow to a wide moving jam. This is supported by the fact that the so called F->S transition (from free flow to synchronized t...
The Phase Transition to Eternal Inflation
Creminelli, Paolo; Dubovsky, Sergei; Nicolis, Alberto; Senatore, Leonardo; Zaldarriaga, Matias
2008-01-01
For slow-roll inflation we study the phase transition to the eternal regime. Starting from a finite inflationary volume, we consider the volume of the universe at reheating as order parameter. We show that there exists a critical value for the classical inflaton speed, \\dot\\phi^2/H^4 = 3/(2 \\pi^2), where the probability distribution for the reheating volume undergoes a sharp transition. In particular, for sub-critical inflaton speeds all distribution moments become infinite. We show that at t...
Phase transitions in Pareto optimal complex networks.
Seoane, Luís F; Solé, Ricard
2015-09-01
The organization of interactions in complex systems can be described by networks connecting different units. These graphs are useful representations of the local and global complexity of the underlying systems. The origin of their topological structure can be diverse, resulting from different mechanisms including multiplicative processes and optimization. In spatial networks or in graphs where cost constraints are at work, as it occurs in a plethora of situations from power grids to the wiring of neurons in the brain, optimization plays an important part in shaping their organization. In this paper we study network designs resulting from a Pareto optimization process, where different simultaneous constraints are the targets of selection. We analyze three variations on a problem, finding phase transitions of different kinds. Distinct phases are associated with different arrangements of the connections, but the need of drastic topological changes does not determine the presence or the nature of the phase transitions encountered. Instead, the functions under optimization do play a determinant role. This reinforces the view that phase transitions do not arise from intrinsic properties of a system alone, but from the interplay of that system with its external constraints.
Directory of Open Access Journals (Sweden)
Hroboňová Katarína
2016-06-01
Full Text Available The HPLC by using chiral stationary phases based on macrocyclic antibiotics, dimethylphenyl carbamate cyklofructan 7 and β-cyclodextrin in terms of polar-organic separation mode (mobile phase methanol/acetonitrile/acetic acid/triethylamine were used for enantioseparation of alkoxy derivatives of phenylcarbamic acid. The effect of the analyte structures on the efficiency of enantioseparation was investigated. The most suitable stationary phase was teicoplanin aglycone, where the separations of the enantiomers were obtained (the resolution value from 0.65 to 2.90, depending on the structure of the analyte. Significant effect on the resolution of the enantiomers has position of alkoxy substituent in the hydrophobic part of the molecule. The enantiorecognition was achieved for 3-alkoxysubstituted derivatives.
Thermalon mediated phase transitions in Gauss-Bonnet gravity
Hennigar, Robie A; Mbarek, Saoussen
2015-01-01
Thermalons can mediate phase transitions between different vacua in higher curvature gravity, potentially changing the asymptotic structure of the spacetime. Treating the cosmological constant as a dynamical parameter, we study these phase transitions in the context of extended thermodynamic phase space. We find that in addition to the AdS to dS phase transitions previously studied, thermal AdS space can undergo a phase transition to an asymptotically flat black hole geometry. In the context of AdS to AdS transitions, we comment on the similarities and differences between thermalon transitions and the Hawking-Page transition.
Phase Transitions in Models of Bird Flocking
Christodoulidi, H; Bountis, T
2013-01-01
The aim of the present paper is to elucidate the transition from collective to random behavior exhibited by various mathematical models of bird flocking. In particular, we compare Vicsek's model [Viscek et al., Phys. Rev. Lett. 75, 1226 -- 1229 (1995)] with one based on topological considerations. The latter model is found to exhibit a first order phase transition from flocking to decoherence, as the 'noise parameter' of the problem is increased, whereas Viscek's model gives a second order transition. Refining the topological model in such a way that birds are influenced mostly by the birds in front of them, less by the ones at their sides and not at all by those behind them (because they do not see them), we find a behavior that lies in between the two models. Finally, we propose a novel mechanism for preserving the flock's cohesion, without imposing artificial boundary conditions or attracting forces.
The Next Generation Transit Survey - Prototyping Phase
McCormac, James; Wheatley, Peter; West, Richard; Walker, Simon; Bento, Joao; Skillen, Ian; Faedi, Francesca; Burleigh, Matt; Casewell, Sarah; Chazelas, Bruno; Genolet, Ludovic; Gibson, Neale; Goad, Mike; Lawrie, Katherine; Ryans, Robert; Todd, Ian; Udry, Stephan; Watson, Christopher
2016-01-01
We present the prototype telescope for the Next Generation Transit Survey, which was built in the UK in 2008/09 and tested on La Palma in the Canary Islands in 2010. The goals for the prototype system were severalfold: to determine the level of systematic noise in an NGTS-like system; demonstrate that we can perform photometry at the (sub) millimagnitude level on transit timescales across a wide field; show that it is possible to detect transiting super-Earth and Neptune-sized exoplanets and prove the technical feasibility of the proposed planet survey. We tested the system for around 100 nights and met each of the goals above. Several key areas for improvement were highlighted during the prototyping phase. They have been subsequently addressed in the final NGTS facility which was recently commissioned at ESO Cerro Paranal, Chile.
Lu, Yangfang; Wang, Hui; Wang, Guiming; Wang, Yan; Gu, Xue; Yan, Chao
2015-03-01
Non-porous C18 silica gel stationary phase (1 µm) was prepared and applied to chiral separation in pressurized capillary electrochromatography (pCEC) for the enantioseparation of various basic compounds. The non-porous silica particles (1 µm) were synthesized using modified St6ber method. C18 stationary phase (1 µm) was prepared by immobilization of chloro-dimethyl-octadecylsilane. Using carboxymethyl-β-cyclodextrin (CM-β-CD) as the chiral additive, the pCEC conditions including the content of acetonitrile (ACN), concentration of buffer, pH, the concentration of chiral additive and flow rate as well as applied voltage were investigated to obtain the optimal pCEC conditions for the separation of four basic chiral compounds. The column provided an efficiency of up to 190,000 plates/m. Bupropion hydrochloride, clenbuterol hydrochloride, metoprolol tartrate, and esmolol hydrochloride were baseline separated under the conditions of 5 mmol/L ammonium acetate buffer at pH 4. 0 with 20% (v/ v) acetonitrile, and 15 mmol/L CM-β-CD as the chiral additive. The applied voltage was 2 kV and flow rate was 0.03 mL/min with splitting ratio of 300:1. The resolution were 1.55, 2.82, 1. 69, 1. 70 for bupropion hydrochloride, clenbuterol hydrochloride, metoprolol tartrate, esmolol hydrochloride, respectively. The C18 coverage was improved by repeating silylation method. The synthesized 1 µm C18 packings have better mechanical strength and longer service life because of the special, non-porous structure. The column used in pCEC mode showed better separation of the racemates and a higher rate compared with those used in the capillary liquid chromatography (cLC) mode. This study provided an alternative way for the method of pCEC enantioseparation with chiral additives in the mobile phase and demonstrated the feasibility of micron particle stationary phase in chiral separation. PMID:26182460
A nonequilibrium phase transition in immune response
Institute of Scientific and Technical Information of China (English)
Zhang Wei; Qi An-Shen
2004-01-01
The dynamics of immune response correlated to signal transduction in immune thymic cells (T cells) is studied.In particular, the problem of the phosphorylation of the immune-receptor tyrosine-based activation motifs (ITAM) is explored. A nonlinear model is established on the basis of experimental observations. The behaviours of the model can be well analysed using the concepts of nonequilibrium phase transitions. In addition, the Riemann-Hugoniot cusp catastrophe is demonstrated by the model. Due to the application of the theory of nonequilibrium phase transitions,the biological phenomena can be clarified more precisely. The results can also be used to further explain the signal transduction and signal discrimination of an important type of immune T cell.
Nonequilibrium phase transitions in biomolecular signal transduction
Smith, Eric; Krishnamurthy, Supriya; Fontana, Walter; Krakauer, David
2011-11-01
We study a mechanism for reliable switching in biomolecular signal-transduction cascades. Steady bistable states are created by system-size cooperative effects in populations of proteins, in spite of the fact that the phosphorylation-state transitions of any molecule, by means of which the switch is implemented, are highly stochastic. The emergence of switching is a nonequilibrium phase transition in an energetically driven, dissipative system described by a master equation. We use operator and functional integral methods from reaction-diffusion theory to solve for the phase structure, noise spectrum, and escape trajectories and first-passage times of a class of minimal models of switches, showing how all critical properties for switch behavior can be computed within a unified framework.
Phase transitions: An overview with a view
Energy Technology Data Exchange (ETDEWEB)
Gleiser, M. [Dartmouth Coll., Hanover, NH (United States)
1997-10-01
The dynamics of phase transitions plays a crucial role in the so- called interface between high energy particle physics and cosmology. Many of the interesting results generated during the last fifteen years or so rely on simplified assumptions concerning the complex mechanisms typical of nonequilibrium field theories. After reviewing well-known results concerning the dynamics of first and second order phase transitions, I argue that much is yet to be understood, in particular in situations where homogeneous nucleation theory does not apply. I present a method to deal with departures from homogeneous nucleation, and compare its efficacy with numerical simulations. Finally, I discuss the interesting problem of matching numerical simulations of stochastic field theories with continuum models.
Extracellular ice phase transitions in insects.
Hawes, T C
2014-01-01
At temperatures below their temperature of crystallization (Tc), the extracellular body fluids of insects undergo a phase transition from liquid to solid. Insects that survive the transition to equilibrium (complete freezing of the body fluids) are designated as freeze tolerant. Although this phenomenon has been reported and described in many Insecta, current nomenclature and theory does not clearly delineate between the process of transition (freezing) and the final solid phase itself (the frozen state). Thus freeze tolerant insects are currently, by convention, described in terms of the temperature at which the crystallization of their body fluids is initiated, Tc. In fact, the correct descriptor for insects that tolerate freezing is the temperature of equilibrium freezing, Tef. The process of freezing is itself a separate physical event with unique physiological stresses that are associated with ice growth. Correspondingly there are a number of insects whose physiological cryo-limits are very specifically delineated by this transitional envelope. The distinction also has considerable significance for our understanding of insect cryobiology: firstly, because the ability to manage endogenous ice growth is a fundamental segregator of cryotype; and secondly, because our understanding of internal ice management is still largely nascent.
Quantum Phase Transitions in the BKL Universe
D'Odorico, Giulio
2015-01-01
We study quantum corrections to the classical Bianchi I and Bianchi IX universes. The modified dynamics is well-motivated from the asymptotic safety program where the short-distance behavior of gravity is governed by a non-trivial renormalization group fixed point. The correction terms induce a phase transition in the dynamics of the model, changing the classical, chaotic Kasner oscillations into a uniform approach to a point singularity. The resulting implications for the microscopic structure of spacetime are discussed.
Phase transitions in Nowak Sznajd opinion dynamics
Wołoszyn, Maciej; Stauffer, Dietrich; Kułakowski, Krzysztof
2007-05-01
The Nowak modification of the Sznajd opinion dynamics model on the square lattice assumes that with probability β the opinions flip due to mass-media advertising from down to up, and vice versa. Besides, with probability α the Sznajd rule applies that a neighbour pair agreeing in its two opinions convinces all its six neighbours of that opinion. Our Monte Carlo simulations and mean-field theory find sharp phase transitions in the parameter space.
Unprovability and phase transitions in Ramsey theory
De Smet, Michiel
2011-01-01
The first mathematically interesting, first-order arithmetical example of incompleteness was given in the late seventies and is know as the Paris-Harrington principle. It is a strengthened form of the finite Ramsey theorem which can not be proved, nor refuted in Peano Arithmetic. In this dissertation we investigate several other unprovable statements of Ramseyan nature and determine the threshold functions for the related phase transitions. Chapter 1 sketches out the historical development...
Quantum phase transitions in constrained Bose systems
Bonnes, Lars
2011-01-01
This doctoral thesis studies low dimensional quantum systems that can be realized in recent cold atom experiments. From the viewpoint of quantum statistical mechanics, the main emphasis is on the detailed study of the different quantum and thermal phases and their transitions using numerical methods, such as quantum Monte Carlo and the Tensor Network Renormalization Group. The first part of this work deals with a lattice Boson model subject to strong three-body losses. In a quantum-Zeno li...
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
The influence of different alcohol modifiers in mobile phase on the chiral separation of 4｀-methoxyl flavanone, 5-methoxyl flavanone and 6-methoxyl flavanone on cellulose tris (3, 5-dimethylphenylcarbamate) (CDMPC) column was studied and the chiral recognition mechanism was discussed. Using hexane-tert-butanol (1.31 mol L-1) as the mobile phase, those three methoxyl flavanones were excellently separated on CDMPC chiral column.
Institute of Scientific and Technical Information of China (English)
WANG Xiao-Ming; ZHOU Bang-Rong
2007-01-01
A general research on chiral symmetry restoring phase transitions at zero temperature and finite chemical potentials under electrical neutrality condition has been conducted in a Nambu-Jona-Lasinio model to describe twoflavor normal quark matter. Depending on whether mo/A, the ratio of dynamical quark mass in vacuum and the 3D momentum cutoff in the loop integrals, is less or greater than 0.413, the phase transition will be of the second or first order. A complete phase diagram of u quark chemical potential versus mo is given. With the electrical neutrality constraint, the region where the second order phase transition happens will be wider than the one without electrical neutrality limitation. The results also show that, for the value of m0/∧ from QCD phenomenology, the phase transition must be of the first order.
Wu, Haixia; Wang, Dongqiang; Zhao, Jianchao; Ke, Yanxiong; Liang, Xinmiao
2016-01-01
A novel chiral stationary phase combining quinine and crown ether (QN-CR CSP) was developed to separate amino acid enantiomers. This CSP showed good enantioselectivity for some amino acids. Since the synergistic effect of ion exchange and complexation in chiral recognition of amino acids, a new adsorption isotherm was built. Using the method of frontal analysis by characteristic point (FACP), the adsorption isotherms of tryptophan (Trp) under different mobile phase conditions were determined and fitted the proposed adsorption isotherm model well. With the increase of the competition between metal cationic and amino to crown ether, the equilibrium constant of complexing adsorption was found increased. The chiral separation ability was decreased. The adsorption isotherm improved the understanding of the retention behavior of amino acids on QN-CR CSP, which was also benefit to optimize the structure of the stationary phase.
Holographic phase transition in a non-critical holographic model
Cui, Sheng-liang; Gao, Yi-hong; Xu, Wei-shui
2010-01-01
We consider a holographic model constructed from the intersecting brane configuration D4-$\\bar{\\rm{D4}}$/D4 in noncritical string theory. We study the chiral phase diagram of this holographic QCD-like model with a finite baryon chemical potential through the supergravity dual approximation.
Wu, Haoran; Yao, Shun; Qian, Guofei; Yao, Tian; Song, Hang
2015-10-30
Aqueous two-phase systems (ATPS) based on tropine type chiral ionic liquids and inorganic salt solution were designed and prepared for the enantiomeric separation of racemic phenylalanine. The phase behavior of IL-based ATPS was comprehensive investigated, and phase equilibrium data were correlated by Merchuk equation. Various factors were also systematically investigated for their influence on separation efficiency. Under the appropriate conditions (0.13g/g [C8Tropine]pro, 35mg/g Cu(Ac)2, 20mg/g d,l-phenylalanine, 0.51g/g H2O and 0.30g/g K2HPO4), the enantiomeric excess value of phenylalanine in solid phase (mainly containing l-enantiomer) was 65%. Finally, the interaction mechanism was studied via 1D and 2D NMR. The results indicate that d-enantiomer of phenylalanine interacts more strongly with chiral ILs and Cu(2+) based on the chiral ion-pairs space coordination mechanism, which makes it tend to remain in the top IL-rich phase. By contrast, l-enantiomer is transferred into the solid phase. Above chiral ionic liquids aqueous two-phase systems have demonstrated obvious resolution to racemic phenylalanine and could be promising alterative resolution approach for racemic amino acids in aqueous circumstance.
Chiral-phase high-performance liquid chromatography of rotenoid racemates
Abidi, S.L.
1987-01-01
The high-performance liquid chromatograhic (HPLC) behavior of parent rotenoids (type I) and the hydroxyl-analogues (type II) on three different chiral stationary phases (CSPs) was studied. Separations of optical isomers were achieved in various degrees depending largely upon the rotenoidal structures and the CSP types employed. Enantiomers of all but elliptone compounds were separable on β-cyclodextrin-bonded silica (CDS). Without exception, the 12a-hydroxyrotenoid antipodes were resolved on Pirkle's phenylglycine-bonded silica (PGS) despite unsuccessful attenmpts to resolve the type I rotenoidal racemates. Conversely, optical resolution of the latter rotenoids was accomplished by using a helical polytriphenylmethylacrylate-coated silica (TPS) column and the observed separation factors (α values) ranged from 1.14 to 1.90. The results from HPLC of type II rotenoids on TPS (α = 1.00–1.63) suggested that variations in E-ring structures had profound influence on the resolution outcome. Conjugated double bonds on the E-ring and the desisopropylation of the five-membered E-ring ot type II rotenoids appeared to be important structural features for chiral recognition involving the TPS substrate. In both reversed-phase (CDS) and normal-pahse (PGS and TPS) HPLC modes, the less polar enantiomers were the 6aβ,12aβ-rotenoids as observed in most cases, though this relationship was reversed in the cases of deguelin and hydroxyelliptone probably due to conformational effects of rotenoidal ring systems.
Phase Transitions in Model Active Systems
Redner, Gabriel S.
The amazing collective behaviors of active systems such as bird flocks, schools of fish, and colonies of microorganisms have long amazed scientists and laypeople alike. Understanding the physics of such systems is challenging due to their far-from-equilibrium dynamics, as well as the extreme diversity in their ingredients, relevant time- and length-scales, and emergent phenomenology. To make progress, one can categorize active systems by the symmetries of their constituent particles, as well as how activity is expressed. In this work, we examine two categories of active systems, and explore their phase behavior in detail. First, we study systems of self-propelled spherical particles moving in two dimensions. Despite the absence of an aligning interaction, this system displays complex emergent dynamics, including phase separation into a dense active solid and dilute gas. Using simulations and analytic modeling, we quantify the phase diagram and separation kinetics. We show that this nonequilibrium phase transition is analogous to an equilibrium vapor-liquid system, with binodal and spinodal curves and a critical point. We also characterize the dense active solid phase, a unique material which exhibits the structural signatures of a crystalline solid near the crystal-hexatic transition point, as well as anomalous dynamics including superdiffusive motion on intermediate timescales. We also explore the role of interparticle attraction in this system. We demonstrate that attraction drastically changes the phase diagram, which contains two distinct phase-separated regions and is reentrant as a function of propulsion speed. We interpret this complex situation with a simple kinetic model, which builds from the observed microdynamics of individual particles to a full description of the macroscopic phase behavior. We also study active nematics, liquid crystals driven out of equilibrium by energy-dissipating active stresses. The equilibrium nematic state is unstable in these
Mechanical analog for a quantum-chromodynamic phase transition
Energy Technology Data Exchange (ETDEWEB)
Salomone, A.; Schechter, J.
1982-07-15
A simple mechanical model involving a pendulum and a spring is shown to give the same phase-transition behavior as that of either the effective chiral Lagrangian for one-flavor QCD or the massive Schwinger model. This model, which also has been studied in catastrophe theory, permits us to get a nice understanding of what at first appears to be a complicated system. We also construct and analyze a mechanical analog model for the two-flavor case. The latter has a similar behavior, in general, but does present some interesting new features. With this experience under our belts we are able to straightforwardly analyze the situation with an arbitrary number of flavors. We also discuss what the zero-flavor (i.e., pure QCD) limit of the effective Lagrangian should look like and give a formula for the ground-state energy as a function of the instanton angle theta. A number of other questions related to the QCD effective Lagrangian are investigated.
Institute of Scientific and Technical Information of China (English)
GE,Jin; ZHAO,Liang; SHI,Yan-Ping
2008-01-01
A novel cellulose tris(N-3,5-dimethylphenylcarbamate) (CDMPC) chiral stationary phase (CSP) was prepared by coating CDMPC on TiO2/SiO2, which was prepared by coating titania nanoparticles on silica through a self-assemble technique. At first, 2-hydroxyl-phenyl acetonitrile and α-phenylethanol were separated on this new CSP to evaluate the chiral separation ability. Then, two pesticides, matalaxyl and diclofop-methyl were separated.The influence of the mobile phase composition on the enantioselectivity was discussed, and the repeatability and stability of the CSP were studied too.
Berry Phases, Quantum Phase Transitions and Chern Numbers
Contreras, H. A.; Reyes-Lega, A. F.
2007-01-01
We study the relation between Chern numbers and Quantum Phase Transitions (QPT) in the XY spin-chain model. By coupling the spin chain to a single spin, it is possible to study topological invariants associated to the coupling Hamiltonian. These invariants contain global information, in addition to the usual one (obtained by integrating the Berry connection around a closed loop). We compute these invariants (Chern numbers) and discuss their relation to QPT. In particular we show that Chern nu...
Kagome Chiral Spin Liquid as a Gauged U (1 ) Symmetry Protected Topological Phase
He, Yin-Chen; Bhattacharjee, Subhro; Pollmann, Frank; Moessner, R.
2015-12-01
While the existence of a chiral spin liquid (CSL) on a class of spin-1 /2 kagome antiferromagnets is by now well established numerically, a controlled theoretical path from the lattice model leading to a low-energy topological field theory is still lacking. This we provide via an explicit construction starting from reformulating a microscopic model for a CSL as a lattice gauge theory and deriving the low-energy form of its continuum limit. A crucial ingredient is the realization that the bosonic spinons of the gauge theory exhibit a U (1 ) symmetry protected topological (SPT) phase, which upon promoting its U (1 ) global symmetry to a local gauge structure ("gauging"), yields the CSL. We suggest that such an explicit lattice-based construction involving gauging of a SPT phase can be applied more generally to understand topological spin liquids.
Effect of vacuum polarization in system of two three-phase chiral bags
Malakhov, I Y
2002-01-01
The self-consistent solutions describing the system of two interacting bags are obtained for the model of the three-phase chiral quark bags in the (1 + 1)-dimensional case. Special attention thereby is paid to studying the role of the fermions vacuum polarization inside the bags in the system dynamics and the boson field connecting (interpolating) the bags is accounted for only at the single-boson exchange level. The renormalized complete energy of the system is studied as the function of the parameters characterizing the geometry of the problem and the bags additional characteristics originating in the (1 + 1)-dimensional case. It is shown that the vacuum polarization in the system of two three-phase bags leads to origination of strong nonlinear interaction at small distances whereby in dependence on the bags characteristics this may be both repulsion and attraction
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Three new hybrid organic/inorganic polymeric ligand-exchange chiral stationary phases were developed by radical chain transfer reaction and surface grafting on silica gel, and successfully used for the enantioseparations of DL-amino acids and DL-hydroxyl acids. The resolutions were achieved by using water containing 2.0 × 10-4 mol/L of CuAc2 as a mobile phase, column temperature of 40 ℃, flow rate of 1.0 mL/min and detection at UV 254 mn. The elution order of D-isomer before L-isomer was observed for all DL-amino acids resolved except DL-Pro.
Stability and Existence of Multidimensional Subsonic Phase Transitions
Institute of Scientific and Technical Information of China (English)
Ya-Guang Wang; Zhouping Xin
2003-01-01
The purpose of this paper is to prove the uniform stability of multidimensional subsonic phase transitions satisfying the viscosity-capillarity criterion in a van der Waals fluid, and further to establish the local existence of phase transition solutions.
Phase transitions of ε-HNIW in compound systems
Directory of Open Access Journals (Sweden)
Jing-yuan Zhang
2016-05-01
Full Text Available The heat-induced phase transitions of ε-HNIW, both neat and coated with various additives used in plastic bonded explosives, were investigated using powder X-ray diffraction and differential scanning calorimetry. It was found that ε-HNIW, after being held at 70°C for 60h, remained in the ε-phase. Applying other conditions, various phase transition parameters were determined, including Tc (the critical phase transition temperature, T50 (the temperature at which 50% of the phase transition is complete and T180 (the percentage of γ-HNIW present in samples heated to 180°C. According to the above three parameters, additives were divided into three categories: those that delay phase transition, those that raise the critical temperature and the transition rate, and those that promote the phase transition. Based on the above data, a phase transition mechanism is proposed.
Holography and the Electroweak Phase Transition
Creminelli, P; Rattazzi, Riccardo; Creminelli, Paolo; Nicolis, Alberto; Rattazzi, Riccardo
2002-01-01
We study through holography the compact Randall-Sundrum (RS) model at finite temperature. In the presence of radius stabilization, the system is described at low enough temperature by the RS solution. At high temperature it is described by the AdS-Schwarzshild solution with an event horizon replacing the TeV brane. We calculate the transition temperature T_c between the two phases and we find it to be somewhat smaller than the TeV scale. Assuming that the Universe starts out at T >> T_c and cools down by expansion, we study the rate of the transition to the RS phase. We find that the transition is too slow and the Universe ends up in an old inflation scenario unless tight bounds are satisfied by the model parameters. In particular we find that the AdS curvature must be comparable to the 5D Planck mass and that the radius stabilization mechanism must lead to a sizeable distortion of the basic RS metric.
Second-order phase transitions of pure substances
Schaftenaar, H.P.C.
2009-01-01
In this report we are dealing with the thermodynamic theory of second-order phase transitions or continuous transitions of unary systems. The first classification of these phase transitions is due to Ehrenfest (1933), based on chemical potentials. First-order transitions are changes in which the der
Examining a possible cascade effect in chiral symmetry breaking
Fariborz, Amir H
2016-01-01
We examine a toy model and a cascade effect for confinement and chiral symmetry breaking which consists in several phase transitions corresponding to the formation of bound states and chiral condensates with different number of fermions for a strong group. We analyze two examples: regular QCD where we calculate the "four quark" vacuum condensate and a preon composite model based on QCD at higher scales. In this context we also determine the number of flavors at which the second chiral and confinement phase transitions occur and discuss the consequences.
From the double-stranded helix to the chiral nematic phase of B-DNA: a molecular model
Tombolato, F
2004-01-01
B-DNA solutions of suitable concentration form left-handed chiral nematic phases (cholesterics). Such phases have also been observed in solutions of other stiff or semiflexible chiral polymers; magnitude and handedness of the cholesteric pitch are uniquely related to the molecular features. In this work we present a theoretical method and a numerical procedure which, starting from the structure of polyelectrolytes, lead to the prediction of the cholesteric pitch. Molecular expressions for the free energy of the system are obtained on the basis of steric and electrostatic interactions between polymers; the former are described in terms of excluded volume, while a mean field approximation is used for the latter. Calculations have been performed for 130 bp fragments of B-DNA. The theoretical predictions provide an explanation for the experimental behavior, by showing the counteracting role played by shape and charge chirality of the molecule.
Diffraction studies of ordered phases and phase transitions
International Nuclear Information System (INIS)
Two investigations are reported here. First, monolayers of CF4 physisorbed on the (001) face of graphite have been studied by means of X-ray diffraction experiments carried out at the electron storage ring DORIS in Hamburg. The exfoliated graphite substrate UCAR-ZYX was used in order to obtain a large area for adsorption and hence a large sample. Four two-dimensional solid phases of the CF4 films were seen, including a structure which is 2x2 commensurate relative to the substrate. On compression (by variation of coverage or temperature), this phase transforms to a uniaxially compressed structure ('stripe' phase). Further, at higher coverages a hexagonal structure was seen, incommensurate relative to the substrate, and at low temperatures and coverages, a complicated structure emerged, giving three close diffraction peaks in the powder pattern. Data are presented characterizing the meltings and commensurate to incommensurate transitions. Complementary to the synchrotron X-ray data, a presentation of the theory of synchrotron radiation is given. The second investigation was of the ferromagnetic phase transitions in the randomly diluted, dipolar coupled uniaxial ferromagnets LiTbsub(.3)Ysub(.7)F4 and LiHosub(.3)Ysub(.7)F4 by neutron diffraction at the RIS0 DR 3 reactor. (orig.)
Phase transition in SONFIS&SORST
Owladeghaffari, Hamed
2008-01-01
In this study, we introduce general frame of MAny Connected Intelligent Particles Systems (MACIPS). Connections and interconnections between particles get a complex behavior of such merely simple system (system in system).Contribution of natural computing, under information granulation theory, are the main topics of this spacious skeleton. Upon this clue, we organize two algorithms involved a few prominent intelligent computing and approximate reasoning methods: self organizing feature map (SOM), Neuro- Fuzzy Inference System and Rough Set Theory (RST). Over this, we show how our algorithms can be taken as a linkage of government-society interaction, where government catches various fashions of behavior: solid (absolute) or flexible. So, transition of such society, by changing of connectivity parameters (noise) from order to disorder is inferred. Add to this, one may find an indirect mapping among finical systems and eventual market fluctuations with MACIPS. Keywords: phase transition, SONFIS, SORST, many con...
Collective flow and QCD phase transition
Sorge, H
1999-01-01
In the first part I discuss the sensitivity of collective matter expansion in ultrarelativistic heavy-ion collisions to the transition between quark and hadronic matter (physics of the softest point of the Equation of State). A kink in the centrality dependence of elliptic flow has been suggested as a signature for the phase transition in hot QCD matter. Indeed, preliminary data of NA49 presented at this conference show first indications for the predicted kink. In the second part I have a look at the present theories of heavy-ion reactions. These remarks may also be seen as a critical comment to B. Mueller's summary talk (nucl-th/9906029) presented at this conference.
Locating phase transitions in computationally hard problems
Indian Academy of Sciences (India)
B Ashok; T K Patra
2010-09-01
We discuss how phase-transitions may be detected in computationally hard problems in the context of anytime algorithms. Treating the computational time, value and utility functions involved in the search results in analogy with quantities in statistical physics, we indicate how the onset of a computationally hard regime can be detected and the transit to higher quality solutions be quantified by an appropriate response function. The existence of a dynamical critical exponent is shown, enabling one to predict the onset of critical slowing down, rather than finding it after the event, in the specific case of a travelling salesman problem (TSP). This can be used as a means of improving efficiency and speed in searches, and avoiding needless computations.
Phase transitions in paradigm shift models.
Directory of Open Access Journals (Sweden)
Huiseung Chae
Full Text Available Two general models for paradigm shifts, deterministic propagation model (DM and stochastic propagation model (SM, are proposed to describe paradigm shifts and the adoption of new technological levels. By defining the order parameter m based on the diversity of ideas, Δ, it is studied when and how the phase transition or the disappearance of a dominant paradigm occurs as a cost C in DM or an innovation probability α in SM increases. In addition, we also investigate how the propagation processes affect the transition nature. From analytical calculations and numerical simulations m is shown to satisfy the scaling relation m=1-f(C/N for DM with the number of agents N. In contrast, m in SM scales as m=1-f(α(aN.
Dynamical phase transitions in quantum mechanics
Directory of Open Access Journals (Sweden)
Rotter Ingrid
2012-02-01
Full Text Available The nucleus is described as an open many-body quantum system with a non-Hermitian Hamilton operator the eigenvalues of which are complex, in general. 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 varying only one parameter, the eigenvalue trajectories usually avoid crossing and width bifurcation occurs at the critical value of avoided crossing. An analog spectroscopic redistribution takes place for discrete states below the particle decay threshold. By this means, a dynamical phase transition occurs in the many-level system starting at a critical value of the level density. Hence the properties of the 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 on the collective features of compound nucleus states at high level density is therefore 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 quantum mechanical systems by varying one or two parameters.
Topology in the SU(Nf) chiral symmetry restored phase of unquenched QCD and axion cosmology
Azcoiti, Vicente
2016-01-01
We investigate the topological properties of unquenched QCD on the basis of numerical results of simulations at fixed topological charge, recently reported by Borsanyi et al., and analytical predictions of the dilute instanton gas approximation. We demonstrate that the mean value of the chiral condensate at fixed topological charge is, in both cases, inconsistent with the analytical prediction of the large volume expansion around the saddle point, and argue that the most plausible explanation for the failure of the saddle point expansion is a vacuum energy density theta-independent at high temperatures, but surprisingly not too high (T\\sim 2T_c), a result which would imply a vanishing topological susceptibility, and the absence of all physical effects of the U(1) axial anomaly at these temperatures. We also show that under a general assumption concerning the high temperature phase of QCD, where the SU(Nf)_A symmetry is restored, the analytical prediction for the chiral condensate at fixed topological charge i...
Phases and phase transitions in the algebraic microscopic shell model
Directory of Open Access Journals (Sweden)
Georgieva A. I.
2016-01-01
Full Text Available We explore the dynamical symmetries of the shell model number conserving algebra, which define three types of pairing and quadrupole phases, with the aim to obtain the prevailing phase or phase transition for the real nuclear systems in a single shell. This is achieved by establishing a correspondence between each of the pairing bases with the Elliott’s SU(3 basis that describes collective rotation of nuclear systems. This allows for a complete classification of the basis states of different number of particles in all the limiting cases. The probability distribution of the SU(3 basis states within theirs corresponding pairing states is also obtained. The relative strengths of dynamically symmetric quadrupole-quadrupole interaction in respect to the isoscalar, isovector and total pairing interactions define a control parameter, which estimates the importance of each term of the Hamiltonian in the correct reproduction of the experimental data for the considered nuclei.
Melonic phase transition in group field theory
Baratin, Aristide; Oriti, Daniele; Ryan, James P; Smerlak, Matteo
2013-01-01
Group field theories have recently been shown to admit a 1/N expansion dominated by so-called `melonic graphs', dual to triangulated spheres. In this note, we deepen the analysis of this melonic sector. We obtain a combinatorial formula for the melonic amplitudes in terms of a graph polynomial related to a higher dimensional generalization of the Kirchhoff tree-matrix theorem. Simple bounds on these amplitudes show the existence of a phase transition driven by melonic interaction processes. We restrict our study to the Boulatov-Ooguri models, which describe topological BF theories and are the basis for the construction of four dimensional models of quantum gravity.
Deconfining phase transition in lattice QCD
International Nuclear Information System (INIS)
We present the first results obtained from the sixteen-processor version of the parallel supercomputer being built at Columbia. The color-deconfining phase transition has been studied fo pure SU(3) gauge theory on lattices with a spatial volume of 163 sites and temporal sizes of 10, 12, and 14 sites. The values found for the critical coupling are 6.07, 6.26, and 6.36, respectively. These results are in agreement with the perturbative predictions of the renormalization group, suggesting that lattice QCD calculations with the parameter β at least as large as 6.07 may approximate the continuum limit
Evolutionary Phase Transitions in Random Environments
Skanata, Antun; Kussell, Edo
2016-07-01
We present analytical results for long-term growth rates of structured populations in randomly fluctuating environments, which we apply to predict how cellular response networks evolve. We show that networks which respond rapidly to a stimulus will evolve phenotypic memory exclusively under random (i.e., nonperiodic) environments. We identify the evolutionary phase diagram for simple response networks, which we show can exhibit both continuous and discontinuous transitions. Our approach enables exact analysis of diverse evolutionary systems, from viral epidemics to emergence of drug resistance.
Berry phase transition in twisted bilayer graphene
Rode, Johannes C.; Smirnov, Dmitri; Schmidt, Hennrik; Haug, Rolf J.
2016-09-01
The electronic dispersion of a graphene bilayer is highly dependent on rotational mismatch between layers and can be further manipulated by electrical gating. This allows for an unprecedented control over electronic properties and opens up the possibility of flexible band structure engineering. Here we present novel magnetotransport data in a twisted bilayer, crossing the energetic border between decoupled monolayers and coupled bilayer. In addition a transition in Berry phase between π and 2π is observed at intermediate magnetic fields. Analysis of Fermi velocities and gate induced charge carrier densities suggests an important role of strong layer asymmetry for the observed phenomena.
A Note on Holography and Phase Transitions
Directory of Open Access Journals (Sweden)
Marc Bellon
2011-01-01
Full Text Available Focusing on the connection between the Landau theory of second-order phase transitions and the holographic approach to critical phenomena, we study diverse field theories in an anti de Sitter black hole background. Through simple analytical approximations, solutions to the equations of motion can be obtained in closed form which give rather good approximations of the results obtained using more involved numerical methods. The agreement we find stems from rather elementary considerations on perturbation of Schrödinger equations.
Dependence of phase transitions on small changes
Stoop, R.
1993-06-01
In this contribution, the generalized thermodynamic formalism is applied to a nonhyperbolic dynamical system in two comparable situations. The change from one situation to the other is small in the sense that the grammar and the singularities of the system are preserved. For the discussion of the effects generated by this change, the generalized entropy functions are calculated and the sets of the specific scaling functions which reflect the phase transition of the system are investigated. It is found that even under mild variations, this set is not invariant.
Enantiomer-Specific State Transfer of Chiral Molecules
Eibenberger, Sandra; Patterson, David
2016-01-01
State-selective enantiomeric excess is realized using microwave-driven coherent population transfer. The method selectively promotes either R- or S- molecules to a higher rotational state by phase-controlled microwave pulses that drive electric-dipole allowed rotational transitions. We demonstrate the method using a racemic mixture of 1,2-propanediol. This method of chiral enrichment can be applied to nearly any chiral molecule that can be vaporized and cooled to the point where rotationally resolved spectroscopy is possible, including molecules that rapidly racemize. The rapid chiral switching demonstrated here allows for new applications in high-precision spectroscopic searches for parity violation in chiral molecules.
Phase transitions and structures of methylammonium compounds
International Nuclear Information System (INIS)
The structures of CD3ND3Cl, CD3ND3I, CD3ND3BF4, (CD3ND3)2SnCl6, and CD3ND3SnBr3 crystals were studied with time-of-flight type high-resolution powder diffractometers using spallation pulsed neutron sources. The orientations of the CD3ND3 cations, including the positions of the D atoms, were determined at all the room temperature phases and at the low temperature phases of CD3ND3I and (CD3ND3)2SnCl6. The heat capacity experiments were also performed for both protonated and deuterated analogs of these compounds. From both structural and thermodynamic points of view, it was found that the transitions are mainly associated with the order-disorder change of the orientations of the CD3ND3 cations. (author)
Topological phase transitions in superradiance lattices
Wang, Da-Wei; Yuan, Luqi; Liu, Ren-Bao; Zhu, Shi-Yao
2015-01-01
The discovery of the quantum Hall effect (QHE) reveals a new class of matter phases, topological insulators (TI's), which have been extensively studied in solid-state materials and recently in photonic structures, time-periodic systems and optical lattices of cold atoms. All these topological systems are lattices in real space. Our recent study shows that Scully's timed Dicke states (TDS) can form a superradiance lattice (SL) in momentum space. Here we report the discovery of topological phase transitions in a two-dimensional SL in electromagnetically induced transparency (EIT). By periodically modulating the three EIT coupling fields, we can create a Haldane model with in-situ tunable topological properties. The Chern numbers of the energy bands and hence the topological properties of the SL manifest themselves in the contrast between diffraction signals emitted by superradiant TDS. The topological superradiance lattices (TSL) provide a controllable platform for simulating exotic phenomena in condensed matte...
Phase transitions in fluids and biological systems
Sipos, Maksim
metric to 16S rRNA metagenomic studies of 6 vertebrate gastrointestinal microbiomes and find that they assembled through a highly non-neutral process. I then consider a phase transition that may occur in nutrient-poor environments such as ocean surface waters. In these systems, I find that the experimentally observed genome streamlining, specialization and opportunism may well be generic statistical phenomena.
Pérez-Quintanilla, Damián; Morante-Zarcero, Sonia; Sierra, Isabel
2014-01-15
New hybrid materials were prepared as novel chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). Pure mesoporous silica (SM) and ethylene-bridged periodic mesostructured organosilica (PMO) were functionalized, by a post-synthesis method, with derivates of erythromycin and vancomycin. N2 adsorption-desorption measurements, XRD, FT-IR, MAS NMR, SEM, TEM and elemental analysis were used to characterize the physico-chemical properties of these mesostructured materials, before and after the modification process. The synthesized particles had non-symmetrical 3-D wormhole-like mesostructure, spherical morphology, and a mean pore diameter between 53 and 59 Å. CSPs prepared were tested for the separation of four chiral β-blockers (atenolol, metoprolol, pindolol and propranolol) in normal phase (NP) and polar organic phase (PO) elution modes. Much stronger chiral interaction was observed in vancomycin-modified silicas. Results obtained in these preliminary studies will permit in future works to improve the synthesis route in order to design mesoporous materials with better performance as a chiral stationary phase for HPLC. PMID:24231079
On Phase Transition of Compressed Sensing in the Complex Domain
Yang, Zai; Xie, Lihua
2011-01-01
The phase transition is a performance measure of the sparsity-undersampling tradeoff in compressed sensing (CS). This letter reports, for the first time, the existence of an exact phase transition for the $\\ell_1$ minimization approach to the complex valued CS problem. This discovery is not only a complementary result to the known phase transition of the real valued CS but also shows considerable superiority of the phase transition of complex valued CS over that of the real valued CS. The results are obtained by extending the recently developed ONE-L1 algorithms to complex valued CS and applying their optimal and iterative solutions to empirically evaluate the phase transition.
Nuclear binding near a quantum phase transition
Elhatisari, Serdar; Rokash, Alexander; Alarcón, Jose Manuel; Du, Dechuan; Klein, Nico; Lu, Bing-nan; Meißner, Ulf-G; Epelbaum, Evgeny; Krebs, Hermann; Lähde, Timo A; Lee, Dean; Rupak, Gautam
2016-01-01
How do protons and neutrons bind to form nuclei? This is the central question of ab initio nuclear structure theory. While the answer may seem as simple as the fact that nuclear forces are attractive, the full story is more complex and interesting. In this work we present numerical evidence from ab initio lattice simulations showing that nature is near a quantum phase transition, a zero-temperature transition driven by quantum fluctuations. Using lattice effective field theory, we perform Monte Carlo simulations for systems with up to twenty nucleons. For even and equal numbers of protons and neutrons, we discover a first-order transition at zero temperature from a Bose-condensed gas of alpha particles (4He nuclei) to a nuclear liquid. Whether one has an alpha-particle gas or nuclear liquid is determined by the strength of the alpha-alpha interactions, and we show that the alpha-alpha interactions depend on the strength and locality of the nucleon-nucleon interactions. The existence of the nearby first-order ...
Electronic phase transitions in ultrathin magnetite films
International Nuclear Information System (INIS)
Magnetite (Fe3O4) shows singular electronic and magnetic properties, resulting from complex electron–electron and electron–phonon interactions that involve the interplay of charge, orbital and spin degrees of freedom. The Verwey transition is a manifestation of these interactions, with a puzzling connection between the low temperature charge ordered state and the dynamic charge fluctuations still present above the transition temperature. Here we explore how these rich physical phenomena are affected by thin film geometries, particularly focusing on the ultimate size limit defined by thicknesses below the minimum bulk unit cell. On one hand, we address the influence of extended defects, such as surfaces or antiphase domains, on the novel features exhibited by thin films. On the other, we try to isolate the effect of the reduced thickness on the electronic and magnetic properties. We will show that a distinct phase diagram and novel charge distributions emerge under reduced dimensions, while holding the local high magnetic moments. Altogether, thin film geometries offer unique possibilities to understand the complex interplay of short- and long-range orders in the Verwey transition. Furthermore, they arise as interesting candidates for the exploitation of the rich physics of magnetite in devices that demand nanoscale geometries, additionally offering novel functionalities based on their distinct properties with respect to the bulk form. (topical review)
Nuclear Binding Near a Quantum Phase Transition
Elhatisari, Serdar; Li, Ning; Rokash, Alexander; Alarcón, Jose Manuel; Du, Dechuan; Klein, Nico; Lu, Bing-nan; Meißner, Ulf-G.; Epelbaum, Evgeny; Krebs, Hermann; Lähde, Timo A.; Lee, Dean; Rupak, Gautam
2016-09-01
How do protons and neutrons bind to form nuclei? This is the central question of ab initio nuclear structure theory. While the answer may seem as simple as the fact that nuclear forces are attractive, the full story is more complex and interesting. In this work we present numerical evidence from ab initio lattice simulations showing that nature is near a quantum phase transition, a zero-temperature transition driven by quantum fluctuations. Using lattice effective field theory, we perform Monte Carlo simulations for systems with up to twenty nucleons. For even and equal numbers of protons and neutrons, we discover a first-order transition at zero temperature from a Bose-condensed gas of alpha particles (4He nuclei) to a nuclear liquid. Whether one has an alpha-particle gas or nuclear liquid is determined by the strength of the alpha-alpha interactions, and we show that the alpha-alpha interactions depend on the strength and locality of the nucleon-nucleon interactions. This insight should be useful in improving calculations of nuclear structure and important astrophysical reactions involving alpha capture on nuclei. Our findings also provide a tool to probe the structure of alpha cluster states such as the Hoyle state responsible for the production of carbon in red giant stars and point to a connection between nuclear states and the universal physics of bosons at large scattering length.
Phase transition in the ABC model.
Clincy, M; Derrida, B; Evans, M R
2003-06-01
Recent studies have shown that one-dimensional driven systems can exhibit phase separation even if the dynamics is governed by local rules. The ABC model, which comprises three particle species that diffuse asymmetrically around a ring, shows anomalous coarsening into a phase separated steady state. In the limiting case in which the dynamics is symmetric and the parameter q describing the asymmetry tends to one, no phase separation occurs and the steady state of the system is disordered. In the present work, we consider the weak asymmetry regime q=exp(-beta/N), where N is the system size, and study how the disordered state is approached. In the case of equal densities, we find that the system exhibits a second-order phase transition at some nonzero beta(c). The value of beta(c)=2pi square root 3 and the optimal profiles can be obtained by writing the exact large deviation functional. For nonequal densities, we write down mean-field equations and analyze some of their predictions. PMID:16241312
Phase transitions in Thirring’s model
Campa, Alessandro; Casetti, Lapo; Latella, Ivan; Pérez-Madrid, Agustín; Ruffo, Stefano
2016-07-01
In his pioneering work on negative specific heat, Walter Thirring introduced a model that is solvable in the microcanonical ensemble. Here, we give a complete description of the phase-diagram of this model in both the microcanonical and the canonical ensemble, highlighting the main features of ensemble inequivalence. In both ensembles, we find a line of first-order phase transitions which ends in a critical point. However, neither the line nor the point have the same location in the phase-diagram of the two ensembles. We also show that the microcanonical and canonical critical points can be analytically related to each other using a Landau expansion of entropy and free energy, respectively, in analogy with what has been done in (Cohen and Mukamel 2012 J. Stat. Mech. P12017). Examples of systems with certain symmetries restricting the Landau expansion have been considered in this reference, while no such restrictions are present in Thirring’s model. This leads to a phase diagram that can be seen as a prototype for what happens in systems of particles with kinematic degrees of freedom dominated by long-range interactions.
Aspects of the cosmological electroweak phase transition
International Nuclear Information System (INIS)
We study the decay of the metastable symmetric phase in the standard model at finite temperature. For the SU(2)-Higgs model the two wave function correction terms Zφ(φ2,T) and Zχ(φ2,T) of Higgs and Goldstone boson fields are calculated to one-loop order. We find that the derivative expansion of the effective action is reliable for Higgs masses smaller than the W-boson mass. We propose a new procedure to evaluate the decay rate by first integrating out the vector field and the components of the scalar fields with non-zero Matsubara frequencies. The static part of the scalar field is treated in the saddle point approximation. As a by-product we obtain a formula for the decay rate of a homogeneous unstable state. The course of the cosmological electroweak phase transition is evaluated numerically for different Higgs boson masses and non-vanishing magnetic mass of the gauge boson. For Higgs masses above ∼ 60 GeV the latent heat can reheat the system to the critical temperature, which qualitatively changes the nature of the transition. (orig.)
Institute of Scientific and Technical Information of China (English)
秦峰; 陈小明; 刘月启; 邹汉法; 王俊德
2005-01-01
The classical method for preparation of covalently boned cellulose derivative chiral stationary phases (CSP) with diisocyanate as spacer was improved. Diisocyanate was firstly allowed to react with 3-aminopropyltriethoxysilane, and the resulting product was then applied as the spacer reagent to immobilize cellulose derivatives onto silica gel. Influences of the amount and the length of the spacer on the optical resolution ability of the CSP were investigated. Comparing improved procedure to classical diisocyanate method, the cross-linking between the glucose units of the cellulose derivatives was avoided to the most extent. With the improved procedure, regio-nonselective ways could be adooted to prepare covalently bonded CSP, which showed an advantage for the rapid preparation.
Stress induced phase transitions in silicon
Budnitzki, M.; Kuna, M.
2016-10-01
Silicon has a tremendous importance as an electronic, structural and optical material. Modeling the interaction of a silicon surface with a pointed asperity at room temperature is a major step towards the understanding of various phenomena related to brittle as well as ductile regime machining of this semiconductor. If subjected to pressure or contact loading, silicon undergoes a series of stress-driven phase transitions accompanied by large volume changes. In order to understand the material's response for complex non-hydrostatic loading situations, dedicated constitutive models are required. While a significant body of literature exists for the dislocation dominated high-temperature deformation regime, the constitutive laws used for the technologically relevant rapid low-temperature loading have severe limitations, as they do not account for the relevant phase transitions. We developed a novel finite deformation constitutive model set within the framework of thermodynamics with internal variables that captures the stress induced semiconductor-to-metal (cd-Si → β-Si), metal-to-amorphous (β-Si → a-Si) as well as amorphous-to-amorphous (a-Si → hda-Si, hda-Si → a-Si) transitions. The model parameters were identified in part directly from diamond anvil cell data and in part from instrumented indentation by the solution of an inverse problem. The constitutive model was verified by successfully predicting the transformation stress under uniaxial compression and load-displacement curves for different indenters for single loading-unloading cycles as well as repeated indentation. To the authors' knowledge this is the first constitutive model that is able to adequately describe cyclic indentation in silicon.
Preon model and cosmological quantum-hyperchromodynamic phase transition
Nishimura, H.; Hayashi, Y.
1987-05-01
From the cosmological viewpoint, we investigate whether or not recent preon models are compatible with the picture of the first-order phase transition from the preon phase to the composite quark-lepton phase. It is shown that the current models accepting the 't Hooft anomaly-matching condition together with quantum hyperchromodynamics are consistent with the cosmological first-order phase transition.
Energy Technology Data Exchange (ETDEWEB)
Zeeb, G.
2006-07-01
In this thesis the thermodynamical properties of strongly interacting hadronic matter and the microscopic in-medium properties of hadrons are investigated at high temperatures and high baryonic densities within a chiral flavor-SU(3) model. The applied model is a generalized {sigma}-{omega} model in mean-field approximation with baryons and mesons as effective degrees of freedom. It is built on spontaneously broken chiral symmetry and scale invariance. The phase transition behavior is systematically analyzed and is thus shown to depend significantly on the couplings of additional heavier hadronic degrees of freedom. A phase diagram in qualitative agreement with current lattice QCD (lQCD) calculations can result from an according coupling of the lowest lying baryonic decuplet to the model. Alternatively, the coupling of a heavy baryonic test-resonance is investigated, which effectively represents the spectrum of the heavy hadronic states. For a certain range of parameters one can even obtain a phase diagram in quantitative agreement with the lQCD calculations and, simultaneously, a successful description of the ground state properties of nuclear matter. It is shown that (within the model assumptions) the phase transition region is experimentally accessible for the CBM experiment at the upcoming FAIR facility at GSI Darmstadt. The chiral model is further applied to particle yield ratios measured in heavy-ion collisions from AGS, SPS and RHIC. For these investigations parameter sets with strongly differing phase diagrams due to different couplings of the baryon decuplet are used and in addition an ideal hadron gas. At the lower and mid collision energies the chiral parameter sets show an improved description as compared to the ideal hadron gas, especially for parameter sets with phase diagrams similar to the lQCD predictions. The interaction within the chiral model leads to in-medium modifications of the chemical potentials and the hadron masses. Therefore the
Phase transitions in high excited nuclear matter
International Nuclear Information System (INIS)
This work is a study of the mechanism of thermal multifragmentation, which takes place in collisions of light relativistic projectiles with heavy targets. This is a new multibody decay process of very hot nuclei (target spectator) with emission of a number of intermediate mass fragments (IMF, 2 4He and 12C with Au. The main results are the following: - The mean IMF multiplicity () saturates at 2.2 ± 0.2.This fact cannot be rendered by the traditional approach with the intranuclear cascade (INC) followed by Statistical Multifragmentation Models (SMM). Considering the expansion phase between two parts of the calculations, the excitation energies and the residual masses are empirically modified to obtain agreement with the measured IMF- multiplicities. The mean excitation energy is found to be around 500 MeV for the beam energies above 5 GeV. This modified model is denoted as INC + α + SMM where α indicates the preequilibrium processes. - The expansion is driven by the thermal pressure. It is larger for 4He and 12C induced collisions because of higher initial temperature. The kinetic energy spectra of IMF become harder and the expansion flow is visible. The total flow energy of the system is estimated to be around 115 MeV both for the He and the carbon beams. - The analysis of the data reveals very interesting information on the fragment space distribution inside the break-up volume. Heavier IMF are formed predominately in the interior of the fragmenting nucleus possibly due to a density gradient. This conclusion is in contrast to the predictions of the Statistical Multifragmentation Model (SMM). - This study of the multifragmentation using a range of projectiles demonstrates a transition from pure '' thermal decay '' (for p + Au collisions) to disintegration '' completed by '' the onset of a collective flow for the heavier projectiles. Nevertheless, in case of reaction caused by fast protons the decay mechanism should be considered as a thermal multifragmentation
Tan, Xulin; Hou, Shicong; Wang, Min
2007-07-01
A novel chiral packing material for high-performance liquid chromatography (HPLC) was prepared by connecting (R)-1-phenyl-2-(4-methylphenyl) ethylamine (PTE) amide derivative of (S)-isoleucine to aminopropyl silica gel through 2-amino-3,5-dinitro-1-carboxamido-benzene unit. This chiral stationary phase was applied to the enantioselective and diastereoselective separation of five pyrethroid insecticides by HPLC under normal phase condition. To achieve satisfactory baseline separation an optimization of the variables of mobile phase composition was required. The two enantiomers of fenpropathrin and four stereoisomers of fenvalerate were baseline separated using hexane-1,2-dichloroethane-2-propanol as mobile phase. The results show that the enantioselectivity of CSP is better than Pirkle type 1-A column for these compounds. Only partial separations for the cypermethrin and cyfluthrin stereoisomers were observed. Seven peaks and eight peaks were observed for cypermethrin and cyfluthrin, respectively. The elution orders were assigned by using different stereoisomer-enriched products.
Ianni, Federica; Sardella, Roccaldo; Carotti, Andrea; Natalini, Benedetto; Lindner, Wolfgang; Lämmerhofer, Michael
2016-01-01
Peptide stereoisomer analysis is of importance for quality control of therapeutic peptides, the analysis of stereochemical integrity of bioactive peptides in food, and the elucidation of the stereochemistry of peptides from a natural chiral pool which often contains one or more D-amino acid residues. In this work, a series of model peptide stereoisomers (enantiomers and diastereomers) were analyzed on a zwitterionic ion-exchanger chiral stationary phase (Chiralpak ZWIX(+) 5 µm), in order to investigate the retention and separation performance for such compounds on this chiral stationary phase and elucidate its utility for this purpose. The goal of the study focused on 1) investigations of the effects of the sample matrix used to dissolve the peptide samples; 2) optimization of the mobile phase (enabling deriving information on factors of relevance for retention and separation); and 3) derivation of structure-selectivity relationships. It turned out that small di- and tripeptides can be well resolved under optimized conditions, typically with resolutions larger than 1.5. The optimized mobile phase often consisted of methanol-tetrahydrofuran-water (49:49:2; v/v/v) with 25 mM formic acid and 12.5 mM diethylamine. This work proposes some guidance on which mobile phases can be most efficiently used for peptide stereoisomer separations on Chiralpak ZWIX. Chirality 28:5-16, 2016. © 2015 Wiley Periodicals, Inc.
Dynamical phase transitions in the two-dimensional ANNNI model
Energy Technology Data Exchange (ETDEWEB)
Barber, M.N.; Derrida, B.
1988-06-01
We study the phase diagram of the two-dimensional anisotropic next-nearest neighbor Ising (ANNNI) model by comparing the time evolution of two distinct spin configurations submitted to the same thermal noise. We clearly se several dynamical transitions between ferromagnetic, paramagnetic, antiphase, and floating phases. These dynamical transitions seem to occur rather close to the transition lines determined previously in the literature.
Detecting the chirality for coupled quantum dots
Energy Technology Data Exchange (ETDEWEB)
Cao Huijuan [Institute for Condensed Matter Physics, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China); Hu Lian [Institute for Condensed Matter Physics, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China)], E-mail: huliancaohj@yahoo.com
2008-04-21
We propose a scheme to detect the chirality for a system consisting of three coupled quantum dots. The chirality is found to be determined by the frequency of the transition between chiral states under the chiral symmetry broken perturbation. The results are important to construct quantum gates and to demonstrate chiral entangle states in the triangle spin dots.
Scaling theory of topological phase transitions.
Chen, Wei
2016-02-10
Topologically ordered systems are characterized by topological invariants that are often calculated from the momentum space integration of a certain function that represents the curvature of the many-body state. The curvature function may be Berry curvature, Berry connection, or other quantities depending on the system. Akin to stretching a messy string to reveal the number of knots it contains, a scaling procedure is proposed for the curvature function in inversion symmetric systems, from which the topological phase transition can be identified from the flow of the driving energy parameters that control the topology (hopping, chemical potential, etc) under scaling. At an infinitesimal operation, one obtains the renormalization group (RG) equations for the driving energy parameters. A length scale defined from the curvature function near the gap-closing momentum is suggested to characterize the scale invariance at critical points and fixed points, and displays a universal critical behavior in a variety of systems examined. PMID:26790004
MAGNETIC FIELDS FROM QCD PHASE TRANSITIONS
Energy Technology Data Exchange (ETDEWEB)
Tevzadze, Alexander G. [Faculty of Exact and Natural Sciences, Javakhishvili Tbilisi State University, 1 Chavchavadze Avenue, Tbilisi 0128 (Georgia); Kisslinger, Leonard; Kahniashvili, Tina [McWilliams Center for Cosmology and Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Brandenburg, Axel, E-mail: aleko@tevza.org [Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden)
2012-11-01
We study the evolution of QCD phase transition-generated magnetic fields (MFs) in freely decaying MHD turbulence of the expanding universe. We consider an MF generation model that starts from basic non-perturbative QCD theory and predicts stochastic MFs with an amplitude of the order of 0.02 {mu}G and small magnetic helicity. We employ direct numerical simulations to model the MHD turbulence decay and identify two different regimes: a 'weakly helical' turbulence regime, when magnetic helicity increases during decay, and 'fully helical' turbulence, when maximal magnetic helicity is reached and an inverse cascade develops. The results of our analysis show that in the most optimistic scenario the magnetic correlation length in the comoving frame can reach 10 kpc with the amplitude of the effective MF being 0.007 nG. We demonstrate that the considered model of magnetogenesis can provide the seed MF for galaxies and clusters.
Scaling theory of topological phase transitions.
Chen, Wei
2016-02-10
Topologically ordered systems are characterized by topological invariants that are often calculated from the momentum space integration of a certain function that represents the curvature of the many-body state. The curvature function may be Berry curvature, Berry connection, or other quantities depending on the system. Akin to stretching a messy string to reveal the number of knots it contains, a scaling procedure is proposed for the curvature function in inversion symmetric systems, from which the topological phase transition can be identified from the flow of the driving energy parameters that control the topology (hopping, chemical potential, etc) under scaling. At an infinitesimal operation, one obtains the renormalization group (RG) equations for the driving energy parameters. A length scale defined from the curvature function near the gap-closing momentum is suggested to characterize the scale invariance at critical points and fixed points, and displays a universal critical behavior in a variety of systems examined.
Information Dynamics at a Phase Transition
Sowinski, Damian
2016-01-01
We propose a new way of investigating phase transitions in the context of information theory. We use an information-entropic measure of spatial complexity known as configurational entropy (CE) to quantify both the storage and exchange of information in a lattice simulation of a Ginzburg-Landau model with a scalar order parameter coupled to a heat bath. The CE is built from the Fourier spectrum of fluctuations around the mean-field and reaches a minimum at criticality. In particular, we investigate the behavior of CE near and at criticality, exploring the relation between information and the emergence of ordered domains. We show that as the temperature is increased from below, the CE displays three essential scaling regimes at different spatial scales: scale free, turbulent, and critical. Together, they offer an information-entropic characterization of critical behavior where the storage and processing of information is maximized at criticality.
The phase transition of Axelrod's model revisited
Reia, Sandro M
2016-01-01
Axelrod's model with $F=2$ cultural features, where each feature can assume $k$ states drawn from a Poisson distribution of parameter $q$, exhibits a continuous nonequilibrium phase transition in the square lattice. Here we use extensive Monte Carlo simulations and finite size scaling to study the critical behavior of the order parameter $\\rho$, which is the fraction of sites that belong to the largest domain of an absorbing configuration averaged over many runs. We find that it vanishes as $\\rho \\sim \\left (q_c^0 - q \\right)^\\beta$ with $\\beta \\approx 0.25$ at the critical point $q_c^0 \\approx 3.10$ and that the exponent that measures the width of the critical region is $\
Phase Transitions in Networks of Memristive Elements
Sheldon, Forrest; di Ventra, Massimiliano
The memory features of memristive elements (resistors with memory), analogous to those found in biological synapses, have spurred the development of neuromorphic systems based on them (see, e.g.,). In turn, this requires a fundamental understanding of the collective dynamics of networks of memristive systems. Here, we study an experimentally-inspired model of disordered memristive networks in the limit of a slowly ramped voltage and show through simulations that these networks undergo a first-order phase transition in the conductivity for sufficiently high values of memory, as quantified by the memristive ON/OFF ratio. We provide also a mean-field theory that reproduces many features of the transition and particularly examine the role of boundary conditions and current- vs. voltage-controlled networks. The dynamics of the mean-field theory suggest a distribution of conductance jumps which may be accessible experimentally. We finally discuss the ability of these networks to support massively-parallel computation. Work supported in part by the Center for Memory and Recording Research at UCSD.
Chiral symmetry in rotating systems
Malik, Sham S.
2015-08-01
The triaxial rotating system at critical angular momentum I ≥Iband exhibits two enatiomeric (the left- and right-handed) forms. These enatiomers are related to each other through dynamical chiral symmetry. The chiral symmetry in rotating system is defined by an operator χ ˆ =Rˆy (π) T ˆ, which involves the product of two distinct symmetries, namely, continuous and discrete. Therefore, new guidelines are required for testing its commutation with the system Hamiltonian. One of the primary objectives of this study is to lay down these guidelines. Further, the possible impact of chiral symmetry on the geometrical arrangement of angular momentum vectors and investigation of observables unique to nuclear chiral-twins is carried out. In our model, the angular momentum components (J1, J2, J3) occupy three mutually perpendicular axes of triaxial shape and represent a non-planar configuration. At certain threshold energy, the equation of motion in angular momentum develops a second order phase transition and as a result two distinct frames (i.e., the left- and right-handed) are formed. These left- and right-handed states correspond to a double well system and are related to each other through chiral operator. At this critical angular momentum, the centrifugal and Coriolis interactions lower the barrier in the double well system. The tunneling through the double well starts, which subsequently lifts the degeneracy among the rotational states. A detailed analysis of the behavior of rotational energies, spin-staggering, and the electromagnetic transition probabilities of the resulting twin-rotational bands is presented. The ensuing model results exhibit similarities with many observed features of the chiral-twins. An advantage of our formalism is that it is quite simple and it allows us to pinpoint the understanding of physical phenomenon which lead to chiral-twins in rotating systems.
The chiral transition and U(1)_A symmetry restoration from lattice QCD using Domain Wall Fermions
Bazavov, A; Buchoff, Michael I; Cheng, Michael; Christ, N H; Ding, H -T; Gupta, Rajan; Hegde, Prasad; Jung, Chulwoo; Karsch, F; Lin, Zhongjie; Mawhinney, R D; Mukherjee, Swagato; Petreczky, P; Soltz, R A; Vranas, P M; Yin, Hantao
2012-01-01
We present results on both the restoration of the spontaneously broken chiral symmetry and the effective restoration of the anomalously broken U(1)_A symmetry in finite temperature QCD at zero chemical potential using lattice QCD. We employ domain wall fermions on lattices with fixed temporal extent N_\\tau = 8 and spatial extent N_\\sigma = 16 in a temperature range of T = 139 - 195 MeV, corresponding to lattice spacings of a \\approx 0.12 - 0.18 fm. In these calculations, we include two degenerate light quarks and a strange quark at fixed pion mass m_\\pi = 200 MeV. The strange quark mass is set near its physical value. We also present results from a second set of finite temperature gauge configurations at the same volume and temporal extent with slightly heavier pion mass. To study chiral symmetry restoration, we calculate the chiral condensate, the disconnected chiral susceptibility, and susceptibilities in several meson channels of different quantum numbers. To study U(1)_A restoration, we calculate spatial ...
Phase transitions in a gas of anyons
MacKenzie, R; Paranjape, M B; Richer, J
2010-01-01
We continue our numerical Monte Carlo simulation of a gas of closed loops on a 3 dimensional lattice, however now in the presence of a topological term added to the action corresponding to the total linking number between the loops. We compute the linking number using certain notions from knot theory. Adding the topological term converts the particles into anyons. Using the correspondence that the model is an effective theory that describes the 2+1-dimensional Abelian Higgs model in the asymptotic strong coupling regime, the topological linking number simply corresponds to the addition to the action of the Chern-Simons term. We find the following new results. The system continues to exhibit a phase transition as a function of the anyon mass as it becomes small \\cite{mnp}, although the phases do not change the manifestation of the symmetry. The Chern-Simons term has no effect on the Wilson loop, but it does affect the {\\rm '}t Hooft loop. For a given configuration it adds the linking number of the 't Hooft loo...
The topological structures in strongly coupled QGP with chiral fermions on the lattice
Sharma, Sayantan; Karsch, Frithjof; Laermann, Edwin; Mukherjee, Swagato
2016-01-01
The nature of chiral phase transition for two flavor QCD is an interesting but unresolved problem. One of the most intriguing issues is whether or not the anomalous U(1) symmetry in the flavor sector is effectively restored along with the chiral symmetry. This may determine the universality class of the chiral phase transition. Since the physics near the chiral phase transition is essentially non-perturbative, we employ first principles lattice techniques to address this issue. We use overlap fermions, which have exact chiral symmetry on the lattice, to probe the anomalous U(1) symmetry violation of 2+1 flavor dynamical QCD configurations with domain wall fermions. The latter also optimally preserves chiral and flavor symmetries on the lattice, since it is known that the remnant chiral symmetry of the light quarks influences the scaling of the chiral condensate in the crossover transition region. We observe that the anomalous U(1) is not effectively restored in the chiral crossover region. We perform a system...
Towards the nuclear matter - quark matter phase transition
International Nuclear Information System (INIS)
The conjectured first order phase transition from cold nuclear to cold quark matter is considered. It is found that non-perturbative effects due to instantons may have a 'smoothing-out' effect on the transition. (author)
Non-equilibrium phase transitions in complex plasma
Sutterlin, K. R.; Wysocki, A.; Rath, C.; Ivlev, A. V.; Thomas, H. M.; Khrapak, S.; Zhdanov, S.; Rubin-Zuzic, M.; W. J. Goedheer,; Fortov, V. E.; Lipaev, A. M.; Molotkov, V. I.; Petrov, O. F.; Morfill, G. E.; Lowen, H.
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 separatio
Directory of Open Access Journals (Sweden)
Yan Wang
2012-10-01
Full Text Available The enantiomers separation of eight pharmaceutical racemates collected in Chinese Pharmacopoeia 2010 (Ch.P2010, including nitrendipine, felodipine, omeprazole, praziquantel, sulpiride, clenbuterol hydrochloride, verapamil hydrochloride and chlorphenamine maleate, was performed on chiral stationary phase of amylose ramification by high performance liquid chromatography (HPLC on Chiralpak AD-H column and Chiralpak AS-H column with the mobile phase consisted of isopropanol and n-hexane. The detection wavelength and the flow rate were set at 254 nm and 0.7 mL/min, respectively. The effects of proportion of organic additives, alcohol displacer and temperature on the separation were investigated. The results indicated that eight chiral drugs were separated on chiral stationary phase of amylase ramification in normal phase chromatographic system. The chromatographic retention and resolution of enantiomers were adjusted by factors, including the changes of the concentration of alcohol displacer in mobile phase, organic alkaline modifier and column temperature. It was shown that the resolution was improved with reducing concentration of alcohol displacer. When the concentration of organic alkaline modifier was 0.2%, the resolution and the peak shape were fairly good. Most racemates mentioned above had the best resolution at column temperature of 25 °C. The best temperature should be kept unchanged in the process of separation so as to obtain stable separation results.
Pressure-induced phase transition in CrO2.
Alptekin, Sebahaddin
2015-12-01
The ab initio constant pressure molecular dynamics technique and density functional theory with generalized gradient approximation (GGA) was used to study the pressure-induced phase transition of CrO2. The phase transition of the rutile (P42/mnm) to the orthorhombic CaCl2 (Pnnm) structure at 30 GPa was determined successfully in a constant pressure simulation. This phase transition was analyzed from total energy calculations and, from the enthalpy calculation, occurred at around 17 GPa. Structural properties such as bulk modules, lattice parameters and phase transition were compared with experimental results. The phase transition at 12 ± 3 GPa was in good agreement with experimental results, as was the phase transition from the orthorhombic CaCl2 (Pnnm) to the monoclinic (P21/c) structure also found at 35 GPa.
Bhushan, Ravi; Dixit, Shuchi
2012-04-01
Six dichloro-s-triazine (DCT) reagents having L-Leu, D-Phg, L-Val, L-Met, L-Ala and L-Met-NH(2) as chiral auxiliaries in cyanuric chloride were introduced for enantioseparation of 13 proteinogenic amino acids. Four other DCTs and six monochloro-s-triazine (MCT) reagents having amino acid amides as chiral auxiliaries were also synthesized. These 16 chiral derivatizing reagents (CDRs) were used for synthesis of diastereomers of all the 13 analytes using microwave irradiation, which were resolved by reversed-phase high-performance liquid chromatography (RP-HPLC) using C18 column and gradient eluting mixture of aqueous TFA and acetonitrile with UV detection at 230 nm. It required only 60-90 s for derivatization using microwave irradiation. Better resolution and lower retention times were observed for the diastereomers prepared with CDRs having amino acids as chiral auxiliaries as compared to counterparts prepared with reagents having amino acid amides as chiral auxiliaries. As the best resolution of all the 13 analytes was observed for their diastereomers prepared using the DCT reagent having L-Leu as chiral auxiliary, this CDR was further employed for derivatization of Lys, Tyr, His and Arg followed by RP-HPLC analysis of resulting diastereomers. The results are discussed in light of acid and amide groups of chiral auxiliaries constituting CDRs, electronegativities of the atoms of achiral moieties constituting CDRs and hydrophobicities of side chains of amino acids constituting CDRs and analytes.
Robust Type-II Weyl Semimetal Phase in Transition Metal Diphosphides XP_{2} (X=Mo, W).
Autès, G; Gresch, D; Troyer, M; Soluyanov, A A; Yazyev, O V
2016-08-01
The recently discovered type-II Weyl points appear at the boundary between electron and hole pockets. Type-II Weyl semimetals that host such points are predicted to exhibit a new type of chiral anomaly and possess thermodynamic properties very different from their type-I counterparts. In this Letter, we describe the prediction of a type-II Weyl semimetal phase in the transition metal diphosphides MoP_{2} and WP_{2}. These materials are characterized by relatively simple band structures with four pairs of type-II Weyl points. Neighboring Weyl points have the same chirality, which makes the predicted topological phase robust with respect to small perturbations of the crystalline lattice. In addition, this peculiar arrangement of the Weyl points results in long topological Fermi arcs, thus making them readily accessible in angle-resolved photoemission spectroscopy. PMID:27541470
Robust Type-II Weyl Semimetal Phase in Transition Metal Diphosphides X P2 (X =Mo , W)
Autès, G.; Gresch, D.; Troyer, M.; Soluyanov, A. A.; Yazyev, O. V.
2016-08-01
The recently discovered type-II Weyl points appear at the boundary between electron and hole pockets. Type-II Weyl semimetals that host such points are predicted to exhibit a new type of chiral anomaly and possess thermodynamic properties very different from their type-I counterparts. In this Letter, we describe the prediction of a type-II Weyl semimetal phase in the transition metal diphosphides MoP2 and WP2 . These materials are characterized by relatively simple band structures with four pairs of type-II Weyl points. Neighboring Weyl points have the same chirality, which makes the predicted topological phase robust with respect to small perturbations of the crystalline lattice. In addition, this peculiar arrangement of the Weyl points results in long topological Fermi arcs, thus making them readily accessible in angle-resolved photoemission spectroscopy.
Phase-separation transitions in asymmetric lipid bilayers
Shimobayashi, Shunsuke F.; Ichikawa, Masatoshi; Taniguchi, Takashi
2015-01-01
Morphological transitions of phase separation associated with the asymmetry of lipid composition were investigated using micrometer-sized vesicles of lipid bilayers made from a lipid mixture. The complete macro-phase-separated morphology undergoes a transition to a micro-phase-separation-like morphology via a lorate morphology as a metastable state. The transition leads to the emergence of monodisperse nanosized domains through repeated domain scission events. Moreover, we have numerically co...
Emergent Geometric Hamiltonian and Insulator-Superfluid Phase Transitions
Zhou, Fei
2005-01-01
I argue that certain bosonic insulator-superfluid phase transitions as an interaction constant varies are driven by emergent geometric properties of insulating states. The {\\em renormalized} chemical potential and distribution of disordered bosons define the geometric aspect of an effective low energy Hamiltonian which I employ to study various resonating states and quantum phase transitions. In a mean field approximation, I also demonstrate that the quantum phase transitions are in the unive...
Primordial Magnetic Fields from Cosmological First Order Phase Transitions
Sigl, Guenter; Olinto, Angela; Jedamzik, Karsten
1996-01-01
We give an improved estimate of primordial magnetic fields generated during cosmological first order phase transitions. We examine the charge distribution at the nucleated bubble wall and its dynamics. We consider instabilities on the bubble walls developing during the phase transition. It is found that damping of these instabilities due to viscosity and heat conductivity caused by particle diffusion can be important in the QCD phase transition, but is probably negligible in the electroweak t...
Discord under the influence of a quantum phase transition
Institute of Scientific and Technical Information of China (English)
Wang Lin-cheng; Shen Jian; Yi Xue-Xi
2011-01-01
This paper studies the discord of a bipartite two-level system coupling to an XY spin-chain environment in a transverse field and investigates the relationship between the discord property and the environment's quantum phase transition. The results show that the quantum discord is also able to characterize the quantum phase transitions. We also discuss the difference between discord and entanglement, and show that quantum discord may reveal more general information than quantum entanglement for characterizing the environment's quantum phase transition.
Quantum phase transition and entanglement in Li atom system
Institute of Scientific and Technical Information of China (English)
2008-01-01
By use of the exact diagonalization method, the quantum phase transition and en- tanglement in a 6-Li atom system are studied. It is found that entanglement appears before the quantum phase transition and disappears after it in this exactly solvable quantum system. The present results show that the von Neumann entropy, as a measure of entanglement, may reveal the quantum phase transition in this model.
Freissinet, C; Buch, A; Szopa, C; Sternberg, R
2013-09-01
The performances of several commercial chiral capillary columns have been evaluated with the aim of determining the one most suitable for enantiomeric separation in a gas chromatograph onboard a space probe. We compared the GC-MS response of three capillary columns coated with different chiral stationary phases (CSP) using volatile chiral organic molecules which are potential markers of a prebiotic organic chemistry. The three different chiral capillary columns are Chirasil-Val, with an amino acid derivative CSP, ChiralDex-β-PM, with a CSP composed of dissolved permethylated β-cyclodextrins in polysiloxane, and Chirasil-Dex, with a CSP made of modified cyclodextrins chemically bonded to the polysiloxane backbone. Both kinetics and thermodynamics studies have been carried out to evaluate the chiral recognition potential in these different types of columns. The thermodynamic parameters also allow a better understanding of the driving forces affecting the retention and separation of the enantiomers. The Chirasil-Dex-CSP displays the best characteristics for an optimal resolution of the chiral compounds, without preliminary derivatization. This CSP had been chosen to be the only chiral column in the Sample Analysis at Mars (SAM) experiment onboard the current Mars Science Laboratory (MSL) mission, and is also part of the Mars Organic Molecules Analyzer (MOMA) gas chromatograph onboard the next Martian mission ExoMars. The use of this column could also be extended to all space missions aimed at studying chirality in space.
Phase transition of holographic entanglement entropy in massive gravity
Zeng, Xiao-Xiong; Li, Li-Fang
2015-01-01
The phase structure of holographic entanglement entropy is studied in massive gravity for the quantum systems with finite and infinite volumes, which in the bulk is dual to calculate the minimal surface area for a black hole and black brane respectively. In the entanglement entropy$-$temperature plane, we find for both the black hole and black brane there is a Van der Waals-like phase transition as the case in thermal entropy$-$temperature plane. That is, there is a first order phase transition for the small charge and a second order phase transition at the critical charge. For the first order phase transition, the equal area law is checked and for the second order phase transition, the critical exponent of the heat capacity is obtained. All the results show that the phase structure of holographic entanglement entropy is the same as that of thermal entropy regardless of the volume of the spacetime on the boundary.
Phase transition of holographic entanglement entropy in massive gravity
Directory of Open Access Journals (Sweden)
Xiao-Xiong Zeng
2016-05-01
Full Text Available The phase structure of holographic entanglement entropy is studied in massive gravity for the quantum systems with finite and infinite volumes, which in the bulk is dual to calculating the minimal surface area for a black hole and black brane respectively. In the entanglement entropy–temperature plane, we find for both the black hole and black brane there is a Van der Waals-like phase transition as the case in thermal entropy–temperature plane. That is, there is a first order phase transition for the small charge and a second order phase transition at the critical charge. For the first order phase transition, the equal area law is checked and for the second order phase transition, the critical exponent of the heat capacity is obtained. All the results show that the phase structure of holographic entanglement entropy is the same as that of thermal entropy regardless of the volume of the spacetime on the boundary.
Holographic phase transition probed by non-local observables
Zeng, Xiao-Xiong
2016-01-01
From the viewpoint of holography, the phase structure of a 5-dimensional Reissner-Nordstr\\"{o}m-AdS black hole is probed by the two point correlation function, Wilson loop, and entanglement entropy. As the case of thermal entropy, we find for all the probes, the black hole undergos a Hawking-Page phase transition, a first order phase transition and a second order phase transition successively before it reaches to a stable phase. In addition, for these probes, we find the equal area law for the first order phase transition is valid always and the critical exponent of the heat capacity for the second order phase transition coincides with that of the mean field theory regardless of the size of the boundary region.
Institute of Scientific and Technical Information of China (English)
LIU,Yue-Qi(刘月启); HAN,Xiao-Qian(韩小茜); Qi,Bang-Feng(齐邦峰); LIU,Chun-Hui(柳春辉); LI,Yong-Min(李永民); CHEN,Li-Ren(陈立仁)
2002-01-01
Cellulose tris(4-methylphenylcarbamate), amylose tris(3,5-dimethylpphenylcarbamate) and amylose tris (phenylcarbamate)were prepared by the method reported by Okamoto and were coated onto an aminopropylated mesoporous spherical silica gel. These final products were used as chiral stationary phases of high performance liquid chromatography for the eighteen structurally related biphenyl conmpounds. The resolution was made using normal-phase methodology with a mobile phase consisting of n-hexane-alcohol (ethanol, 1-propanol, 2-propanol or 1-butanol). The effects of various aliphatic alcohols in the mobile phase were studied. The structural features of the solutes that influence their k'were discussed. A dominant effect of trifluoroaetic acid on chiral separation of aacidicdic solutes was noted.
Mesoscale modeling of phase transition dynamics of thermoresponsive polymers
Li, Zhen; Li, Xuejin; Karniadakis, George Em
2015-01-01
We present a non-isothermal mesoscopic model for investigation of the phase transition dynamics of thermoresponsive polymers. Since this model conserves energy in the simulations, it is able to correctly capture not only the transient behavior of polymer precipitation from solvent, but also the energy variation associated with the phase transition process. Simulations provide dynamic details of the thermally induced phase transition and confirm two different mechanisms dominating the phase transition dynamics. A shift of endothermic peak with concentration is observed and the underlying mechanism is explored.
Nonlinear piezoelectric coefficients of ferroelectrics in the phase transition region
Energy Technology Data Exchange (ETDEWEB)
Iushin, N.K.; Smirnov, S.I.; Turovets, A.G.; Linnik, V.G.; Agishev, B.A.
1987-03-01
Changes in the nonlinear piezoelectric coefficients in ferroelectrics in the phase transition region are investigated experimentally using triglycine sulfate, lead germanate, potassium-lithium tantalate, and cadmium pyroniobate crystals, characterized by phase transitions of the second kind, and also gadolinium and terbium molybdate crystals, characterized by a ferroelectric phase transition of the first kind. In the crystals studied, a significant increase in nonlinear piezoelectric coefficients is observed near the phase transition temperature, which makes these crystals attractive materials for use as the elements of nonlinear acoustoelectronic instruments. 9 references.
Raman study of thermochromic phase transition in tungsten trioxide nanowires
Lu, Dong Yu; Chen, Jian; Chen, Huan Jun; Gong, Li; Deng, Shao Zhi; Xu, Ning Sheng; Liu, Yu Long
2007-01-01
Tungsten trioxide (WO3) nanowires were synthesized by thermal evaporation of tungsten powder in two steps: tungsten suboxide (WO3-x) nanowires were synthesized, and then oxidized in O2 ambient and transformed into WO3 nanowires. Raman spectroscopy was applied to study the thermochromic phase transition of one-dimensional WO3 nanowires. From the temperature dependence of the characteristic mode at 33cm-1 in WO3, the phase transition temperature was determined. It was found that the phase transition of WO3 nanowires was reversible and the phase transition temperatures were even lower than that of WO3 nanopowder.
Theory of ion-chirality relation in ferroelectric liquid crystals
Lahiri, T.; Pal Majumder, T.
2012-04-01
The presence of impurity ions in ferroelectric liquid crystals (FLC) could produce a significant impact on the chirality of the medium with a possible modification in the polarization profile of the system. We theoretically observed these possibilities by considering an in-plane and bulk free energy density for the sample. Based on a suitable chirality transfer formalism, we explained the role of impurity ions in altering the chiral nature of a FLC medium. A continuous transition from modulated phases to uniform phases is also predicted within the framework of this theory. Then, we investigated the possible modification in the polarization profile driven by ionic impurities.
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.
Holness, Howard K; Jamal, Adeel; Mebel, Alexander; Almirall, José R
2012-11-01
A new mechanism is proposed that describes the gas-phase separation of chiral molecules found in amphetamine-type substances (ATS) by the use of high-resolution ion mobility spectrometry (IMS). Straight-chain achiral alcohols of increasing carbon chain length, from methanol to n-octanol, are used as drift gas modifiers in IMS to highlight the mechanism proposed for gas-phase separations of these chiral molecules. The results suggest the possibility of using these achiral modifiers to separate the chiral molecules (R,S) and (S,R)-ephedrine and (S,S) and (R,R)-pseudoephedrine which contain an internal hydroxyl group at the first chiral center and an amino group at the other chiral center. Ionization was achieved with an electrospray source, the ions were introduced into an IMS with a resolving power of 80, and the resulting ion clusters were characterized with a coupled quadrupole mass spectrometer detector. A complementary computational study conducted at the density functional B3LYP/6-31g level of theory for the electronic structure of the analyte-modifier clusters was also performed, and showed either "bridged" or "independent" binding. The combined experimental and simulation data support the proposed mechanism for gas-phase chiral separations using achiral modifiers in the gas phase, thus enhancing the potential to conduct fast chiral separations with relative ease and efficiency.
Kfir, Ofer; Grychtol, Patrik; Turgut, Emrah; Knut, Ronny; Zusin, Dmitriy; Fleischer, Avner; Bordo, Eliyahu; Fan, Tingting; Popmintchev, Dimitar; Popmintchev, Tenio; Kapteyn, Henry; Murnane, Margaret; Cohen, Oren
2016-06-01
Phase matching of circularly polarized high-order harmonics driven by counter-rotating bi-chromatic lasers was recently predicted theoretically and demonstrated experimentally. In that work, phase matching was analyzed by assuming that the total energy, spin angular momentum and linear momentum of the photons participating in the process are conserved. Here we propose a new perspective on phase matching of circularly polarized high harmonics. We derive an extended phase matching condition by requiring a new propagation matching condition between the classical vectorial bi-chromatic laser pump and harmonics fields. This allows us to include the influence of the laser pulse envelopes on phase matching. We find that the helicity dependent phase matching facilitates generation of high harmonics beams with a high degree of chirality. Indeed, we present an experimentally measured chiral spectrum that can support a train of attosecond pulses with a high degree of circular polarization. Moreover, while the degree of circularity of the most intense pulse approaches unity, all other pulses exhibit reduced circularity. This feature suggests the possibility of using a train of attosecond pulses as an isolated attosecond probe for chiral-sensitive experiments.
Phase transitions in a vortex gas
Shah, P A
1994-01-01
It has been shown recently that the motion of solitons at couplings around a critical coupling can be reduced to the dynamics of particles (the zeros of the Higgs field) on a curved manifold with potential. The curvature gives a velocity dependent force, and the magnitude of the potential is proportional to the distance from a critical coupling. In this paper we apply this approximation to determining the equation of state of a gas of vortices in the Abelian Higgs model. We derive a virial expansion using certain known integrals of the metric, and the second virial coefficient is calculated, determining the behaviour of the gas at low densities. A formula for determining higher order coefficients is given. At low densities and temperatures T \\gg \\l the equation of state is of the Van der Waals form (P+b\\frac{N^{2}}{A^{2}})(A-aN) = NT with a=4\\pi and b=-4.89\\pi\\l where \\l is a measure of the distance from critical coupling. It is found that there is no phase transition in a low density type-II gas, but there i...
Swarms, Phase Transitions, and Collective Intelligence
Millonas, M M
1993-01-01
A spacially extended model of the collective behavior of a large number of locally acting organisms is proposed in which organisms move probabilistically between local cells in space, but with weights dependent on local morphogenetic substances, or morphogens. The morphogens are in turn are effected by the passage of an organism. The evolution of the morphogens, and the corresponding flow of the organisms constitutes the collective behavior of the group. Such models have various types of phase transitions and self-organizing properties controlled both by the level of the noise, and other parameters. The model is then applied to the specific case of ants moving on a lattice. The local behavior of the ants is inspired by the actual behavior observed in the laboratory, and analytic results for the collective behavior are compared to the corresponding laboratory results. It is hoped that the present model might serve as a paradigmatic example of a complex cooperative system in nature. In particular swarm models c...
Phase transitions in models of human cooperation
Perc, Matjaž
2016-08-01
If only the fittest survive, why should one cooperate? Why should one sacrifice personal benefits for the common good? Recent research indicates that a comprehensive answer to such questions requires that we look beyond the individual and focus on the collective behavior that emerges as a result of the interactions among individuals, groups, and societies. Although undoubtedly driven also by culture and cognition, human cooperation is just as well an emergent, collective phenomenon in a complex system. Nonequilibrium statistical physics, in particular the collective behavior of interacting particles near phase transitions, has already been recognized as very valuable for understanding counterintuitive evolutionary outcomes. However, unlike pairwise interactions among particles that typically govern solid-state physics systems, interactions among humans often involve group interactions, and they also involve a larger number of possible states even for the most simplified description of reality. Here we briefly review research done in the realm of the public goods game, and we outline future research directions with an emphasis on merging the most recent advances in the social sciences with methods of nonequilibrium statistical physics. By having a firm theoretical grip on human cooperation, we can hope to engineer better social systems and develop more efficient policies for a sustainable and better future.
The Wilson Flow and the finite temperature phase transition
Wandelt, Michèle; Knechtli, Francesco; Günther, Michael
2016-01-01
We consider the determination of the finite temperature phase transition in the Yang--Mills SU(3) gauge theory. We compute the difference of the spatial and temporal energy density at a physical Wilson flow time. This difference is zero in the confined phase and becomes non zero in the deconfined phase. We locate the phase transition by using a new technique based on an exponential smoothing spline. This method is an alternative to the determination of the phase transition based on the Polyak...
Highly birefringent crystal for Raman transitions with phase modulators
Arias, Nieves; Abediyeh, Vahide; Hamzeloui, Saeed; Jeronimo-Moreno, Yasser; Gomez, Eduardo
2016-05-01
We present a system to excite Raman transitions with minimum phase noise. The system uses a phase modulator to generate the phase locked beams required for the transition. We use a long calcite crystal to filter out one of the sidebands, avoiding the cancellation that appears at high detunings for phase modulation. The measured phase noise is limited by the quality of the microwave synthesizer. We use the calcite crystal a second time to produce a co-propagating Raman pair with perpendicular polarizations to drive velocity insensitive Raman transitions. Support from CONACYT and Fundacion Marcos Moshinsky.
The Wilson Flow and the finite temperature phase transition
Wandelt, Michèle; Günther, Michael
2016-01-01
We consider the determination of the finite temperature phase transition in the Yang--Mills SU(3) gauge theory. We compute the difference of the spatial and temporal energy density at a physical Wilson flow time. This difference is zero in the confined phase and becomes non zero in the deconfined phase. We locate the phase transition by using a new technique based on an exponential smoothing spline. This method is an alternative to the determination of the phase transition based on the Polyakov loop susceptibility and can also be used with dynamical fermions.
Van der Waals phase transition in the framework of holography
Zeng, Xiao-Xiong
2015-01-01
Phase structure of the quintessence Reissner-Nordstr\\"{o}m-AdS black hole is probed with 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 similar Van der Waals-like phase transition. To reinforce the 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.
Cosmological Consequences of QCD Phase Transition(s) in Early Universe
Tawfik, A
2008-01-01
We discuss the cosmological consequences of QCD phase transition(s) on the early universe. We argue that our recent knowledge about the transport properties of quark-gluon plasma (QGP) should throw additional lights on the actual time evolution of our universe. Understanding the nature of QCD phase transition(s), which can be studied in lattice gauge theory and verified in heavy ion experiments, provides an explanation for cosmological phenomenon stem from early universe.
Liquid-Gas Phase Transition in Nuclear Equation of State
Lee, S J
1997-01-01
A canonical ensemble model is used to describe a caloric curve of nuclear liquid-gas phase transition. Allowing a discontinuity in the freeze out density from one spinodal density to another for a given initial temperature, the nuclear liquid-gas phase transition can be described as first order. Averaging over various freeze out densities of all the possible initial temperatures for a given total reaction energy, the first order characteristics of liquid-gas phase transition is smeared out to a smooth transition. Two experiments, one at low beam energy and one at high beam energy show different caloric behaviors and are discussed.
Quantum phase transitions in Bose-Fermi systems
Petrellis, D; Iachello, F
2011-01-01
Quantum phase transitions in a system of N bosons with angular momentum L=0,2 (s,d) and a single fermion with angular momentum j are investigated both classically and quantum mechanically. It is shown that the presence of the odd fermion strongly influences the location and nature of the phase transition, especially the critical value of the control parameter at which the phase transition occurs. Experimental evidence for the U(5)-SU(3) (spherical to axially-deformed) transition in odd-even nuclei is presented.
Quantum Monte Carlo simulation of topological phase transitions
Yamamoto, Arata
2016-01-01
We study the electron-electron interaction effects on topological phase transitions by the ab-initio quantum Monte Carlo simulation. We analyze two-dimensional class A topological insulators and three-dimensional Weyl semimetals with the long-range Coulomb interaction. The direct computation of the Chern number shows the electron-electron interaction modifies or extinguishes topological phase transitions.
Experimental and theoretical investigations on shock wave induced phase transitions
Gupta, Satish C.; Sikka, S. K.
2001-06-01
Shock wave loading of a material can cause variety of phase transitions, like polymorphism, amorphization, metallization and molecular dissociations. As the shocked state lasts only for a very short duration (about a few microseconds or less), in-situ microscopic measurements are very difficult. Although such studies are beginning to be possible, most of the shock-induced phase transitions are detected using macroscopic measurements. The microscopic nature of the transition is then inferred from comparison with static pressure data or interpreted by theoretical methods. For irreversible phase transitions, microscopic measurements on recovered samples, together with orientation relations determined from selected area electron diffraction and examination of the morphology of growth of the new phase can provide insight into mechanism of phase transitions. On theoretical side, the current ab initio band structure techniques based on density functional formalism provide capability for accurate computation of the small energy differences (a few mRy or smaller) between different plausible structures. Total energy calculation along the path of a phase transition can furnish estimates of activation barrier, which has implications for understanding kinetics of phase transitions. Molecular dynamics calculations, where the new structure evolves naturally, are becoming increasingly popular especially for understanding crystal to amorphous phase transitions. Illustrations from work at our laboratory will be presented.
Nuclear Liquid-Gas Phase Transition: Experimental Signals
D'Agostino, M.; Bruno, M.; Gulminelli, F.; Cannata, F.; Chomaz, Ph.; Casini, G.; Geraci, E.; Gramegna, F.; Moroni, A.; Vannini, G.
2005-03-01
The connection between the thermodynamics of charged finite nuclear systems and the asymptotically measured partitions in heavy ion collisions is discussed. Different independent signals compatible with a liquid-to-gas-like phase transition are reported. In particular abnormally large fluctuations in the measured observables are presented as a strong evidence of a first order phase transition with negative heat capacity.
Nuclear liquid-gas phase transition: Experimental signals
Energy Technology Data Exchange (ETDEWEB)
D' Agostino, M. [Dipartimento di Fisica and INFN, Bologna (Italy); Bruno, M. [Dipartimento di Fisica and INFN, Bologna (Italy); Gulminelli, F. [LPC Caen (IN2P3-CNRS/ISMRA et Universite), F-14050 Caen Cedex (France); Cannata, F. [Dipartimento di Fisica and INFN, Bologna (Italy); Chomaz, Ph. [GANIL, DSM-CEA/IN2P3-CNRS (France); Casini, G. [INFN Sezione di Firenze (Italy); Geraci, E. [Dipartimento di Fisica and INFN, Bologna (Italy); Gramegna, F. [INFN Laboratorio Nazionale di Legnaro (Italy); Moroni, A. [Dipartimento di Fisica and INFN, Milano (Italy); Vannini, G. [Dipartimento di Fisica and INFN, Bologna (Italy)
2005-03-07
The connection between the thermodynamics of charged finite nuclear systems and the asymptotically measured partitions in heavy ion collisions is discussed. Different independent signals compatible with a liquid-to-gas-like phase transition are reported. In particular abnormally large fluctuations in the measured observables are presented as a strong evidence of a first order phase transition with negative heat capacity.
Multipartite entanglement characterization of a quantum phase transition
Costantini, G.; Facchi, P.; G. Florio; Pascazio, S.
2006-01-01
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.
On the nature of phase transition in solid electrolytes
International Nuclear Information System (INIS)
An attempt is made to precisely measure the solid electrolyte RbAg4I5 conductivity in the vicinity of the phase transition at 208 deg K. Polycrystalline samples obtained by common technique have been used as well as single RbAg4I5 crystals grown from the acetone solution of AgI and RbI. The dependence of conductivity on inverse temperature is given for different samples. The phase transition of the single crystals is accompanied by a jump (approximately 12%) of conductivity. This transfer is reversible, since no hysteresis is found in the +-0.3 deg K vicinity of the phase transition temperature. Polycrystalline samples display no pronounces jump of conductivity, but the conductivity curve has two bends, i.e. the phase transition is ''diffused''. The activation energy before the transition differs from that after the transition
Ruggieri, M; Peng, G X
2016-01-01
We study the influence of external electric, $E$, and magnetic, $B$, fields parallel to each other, and of a chiral chemical potential, $\\mu_5$, on the chiral phase transition of Quantum Chromodynamics. Our theoretical framework is a Nambu-Jona-Lasinio model with a contact interaction. Within this model we compute the critical temperature of chiral symmetry restoration, $T_c$, as a function of the chiral chemical potential and field strengths. We find that the fields inhibit and $\\mu_5$ enhances chiral symmetry breaking, in agreement with previous studies.
Ianni, Federica; Pataj, Zoltán; Gross, Harald; Sardella, Roccaldo; Natalini, Benedetto; Lindner, Wolfgang; Lämmerhofer, Michael
2014-10-10
While aliphatic 2-hydroxyalkanoic acids have been more or less successfully enantioseparated with various chiral stationary phases by HPLC and GC, analogous applications on underivatized aliphatic 3-hydroxyalkanoic acids are completely absent in the scientific literature. With the aim of closing this gap, the enantioseparation of 3-hydroxybutyric acid, 3-hydroxydecanoic acid and 3-hydroxymyristic acid has been performed with two ion-exchange type chiral stationary phases (CSPs): one containing the anion-exchange type tert-butyl carbamoyl quinine chiral selector motif (Chiralpak QN-AX), and the other carrying the new zwitterionic variant based on trans-(S,S)-2-aminocyclohexanesulfonic acid-derivatized quinine carbamate (Chiralpak ZWIX(+)) as the chiral selector and enantiodiscriminating element, respectively. The zwitterionic enantiorecognition material provided better results in terms of enantioselectivity and resolution compared to the anion-exchanger CSP at reduced retention times due to the intramolecular counterion effect imposed by the sulfonic acid moiety and its competition with the 3-hydroxyalkanoic acid analyte for ionic interaction at the quininium-anion exchanger site. It is thus recommended as the CSP of first choice for enantioseparations of the class of aliphatic 3-hydroxyalkanoic acids. With use of polar organic eluent composed of ACN/MeOH/AcOH - 95/5/0.05 (v/v/v), a good compromise in terms of analysis time and enantioresolution quality was accomplished. The major experimental variables have been investigated for optimization of the resolution and allowed to derive information on the enantiorecognition mechanism. Corresponding Chiralpak ZWIX(-), based on pseudo-enantiomeric selector derived from quinidine and trans-(R,R)-2-aminocyclohexanesulfonic acid with opposite configurations provided reversed enantiomer elution orders. It has further to be stressed that these separations can be obtained with mass spectrometry compatible mobile phases.
Pressure-induced phase transitions and metallization in VO2
Bai, Ligang; Li, Quan; Corr, Serena A.; Meng, Yue; Park, Changyong; Sinogeikin, Stanislav V.; Ko, Changhyun; Wu, Junqiao; Shen, Guoyin
2015-03-01
We report the results of pressure-induced phase transitions and metallization in VO2 based on synchrotron x-ray diffraction, electrical resistivity, and Raman spectroscopy. Our isothermal compression experiments at room temperature and 383 K show that the room temperature monoclinic phase (M 1 ,P 21/c ) and the high-temperature rutile phase (R ,P 42/m n m ) of VO2 undergo phase transitions to a distorted M 1 monoclinic phase (M 1' ,P 21/c ) above 13.0 GPa and to an orthorhombic phase (CaCl2-like, P n n m ) above 13.7 GPa, respectively. Upon further compression, both high-pressure phases transform into a new phase (phase X ) above 34.3 and 38.3 GPa at room temperature and 383 K, respectively. The room temperature M 1 -M 1' phase transition structurally resembles the R -CaCl2 phase transition at 383 K, suggesting a second-order displacive type of transition. Contrary to previous studies, our electrical resistivity results, Raman measurements, as well as ab initio calculations indicate that the new phase X , rather than the M 1' phase, is responsible for the metallization under pressure. The metallization mechanism is discussed based on the proposed crystal structure.
Transition to and from the skyrmion lattice phase by electric fields in a magnetoelectric compound
Okamura, Y.; Kagawa, F.; Seki, S.; Tokura, Y.
2016-09-01
Dissipation-less electric control of magnetic state variable is an important target of contemporary spintronics. The non-volatile control of magnetic skyrmions, nanometre-sized spin-swirling objects, with electric fields may exemplify this goal. The skyrmion-hosting magnetoelectric chiral magnet Cu2OSeO3 provides a unique platform for the implementation of such control; however, the hysteresis that accompanies the first-order transition associated with the skyrmion phase is negligibly narrow in practice. Here we demonstrate another method that functions irrespective of the transition boundary. Combination of magnetic-susceptibility measurements and microwave spectroscopy reveals that although the metastable skyrmion lattice is normally hidden behind a more thermodynamically stable conical phase, it emerges under electric fields and persists down to the lowest temperature. Once created, this metastable skyrmion lattice remains without electric fields, establishing a bistability distinct from the transition hysteresis. This bistability thus enables non-volatile electric-field control of the skyrmion lattice even in temperature/magnetic-field regions far from the transition boundary.
Transition to and from the skyrmion lattice phase by electric fields in a magnetoelectric compound.
Okamura, Y; Kagawa, F; Seki, S; Tokura, Y
2016-01-01
Dissipation-less electric control of magnetic state variable is an important target of contemporary spintronics. The non-volatile control of magnetic skyrmions, nanometre-sized spin-swirling objects, with electric fields may exemplify this goal. The skyrmion-hosting magnetoelectric chiral magnet Cu2OSeO3 provides a unique platform for the implementation of such control; however, the hysteresis that accompanies the first-order transition associated with the skyrmion phase is negligibly narrow in practice. Here we demonstrate another method that functions irrespective of the transition boundary. Combination of magnetic-susceptibility measurements and microwave spectroscopy reveals that although the metastable skyrmion lattice is normally hidden behind a more thermodynamically stable conical phase, it emerges under electric fields and persists down to the lowest temperature. Once created, this metastable skyrmion lattice remains without electric fields, establishing a bistability distinct from the transition hysteresis. This bistability thus enables non-volatile electric-field control of the skyrmion lattice even in temperature/magnetic-field regions far from the transition boundary. PMID:27580648
International Nuclear Information System (INIS)
In this thesis we report about an investigation of the finite temperature crossover/phase transition of quantum chromodynamics and the evaluation of the thermodynamic equation of state. To this end the lattice method and the Wilson twisted mass discretisation of the quark action are used. This formulation is known to have an automatic improvement of lattice artifacts and thus an improved continuum limit behaviour. This work presents first robust results using this action for the non-vanishing temperature case. We investigate the chiral limit of the two flavour phase transition with several small values of the pion mass in order to address the open question of the order of the transition in the limit of vanishing quark mass. For the currently simulated pion masses in the range of 300 to 700 MeV we present evidence that the finite temperature transition is a crossover transition rather than a genuine phase transition. The chiral limit is investigated by comparing the scaling of the observed crossover temperature with the mass including several possible scenarios. Complementary to this approach the chiral condensate as the order parameter for the spontaneous breaking of chiral symmetry is analysed in comparison with the O(4) universal scaling function which characterises a second order transition. With respect to thermodynamics the equation of state is obtained from the trace anomaly employing the temperature integral method which provides the pressure and energy density in the crossover region. The continuum limit of the trace anomaly is studied by considering several values of Nτ and the tree-level correction technique.
High pressure phase transitions for CdSe
Indian Academy of Sciences (India)
Bo Kong; Ti-Xian Zeng; Zhu-Wen Zhou; De-Liang Chen; Xiao-Wei Sun
2014-05-01
The structure and pressure-induced phase transitions for CdSe are investigated using first-principles calculations. The pressure-induced phase transition sequence WZ/ZB $\\to$ Rs $\\to$ $\\to$ CsCl for CdSe is drawn reasonably for the fist time, the corresponding transition pressures are 3.8, 29 and 107 GPa, respectively and the intermediate states between the structure and the CsCl structure should exist.
Quantum Phase Transitions in Odd-Mass Nuclei
Leviatan, A; Iachello, F
2011-01-01
Quantum shape-phase transitions in odd-even nuclei are investigated in the framework of the interacting boson-fermion model. Classical and quantum analysis show that the presence of the odd fermion strongly influences the location and nature of the phase transition, especially near the critical point. Experimental evidence for the occurrence of spherical to axially-deformed transitions in odd-proton nuclei Pm, Eu and Tb (Z=61, 63, 65) is presented.
Phase transition of Bose—Einstein condensate under decoherence
International Nuclear Information System (INIS)
The effect of decoherence on the phase transition of a Bose—Einstein condensate in a symmetric double-well potential is determined by the mean atom number difference. It still has two phases, the tunneling phase and the self-trapping phase, even under decoherence. The density matrix and the operator fidelity also show very different behaviors in the two phases. This suggests that operator fidelity can be used to characterize the phase transition of this Bose—Einstein condensate model, even under decoherence. (condensed matter: structural, mechanical, and thermal properties)
Pressure-induced phase transitions and metallization in VO2
Bai, Ligang; Li, Quan; Corr, Serena A; Meng, Yue; Park, Changyong; Sinogeikin, Stanislav V.; Ko, Changhyun; Wu, Junqiao; Shen, Guoyin
2015-01-01
We report the results of pressure-induced phase transitions and metallization in VO2 based on synchrotron x-ray diffraction, electrical resistivity, and Raman spectroscopy. Our isothermal compression experiments at room temperature and 383 K show that the room temperature monoclinic phase (M1,P21/c) and the high-temperature rutile phase (R,P42/mnm) of VO2 undergo phase transitions to a distorted M1 monoclinic phase (M1′,P21/c) above 13.0 GPa and to an orthorhombic phase (CaCl2-like, Pnnm) abo...
Phase transition and PTCR effect in erbium doped BT ceramics
International Nuclear Information System (INIS)
Highlights: ► Erbium influence the dielectric response BaTiO3 ceramics. ► Features of the phase transition are not explained by phenomenological models. ► Relaxation parameters do not show influence on ferroelectric–paraelectric phase transition. ► Dielectric anomaly on BET phase transition is associated with the PTCR effect. - Abstract: In this work the dielectric behaviour and main features of the phase transition of BaTiO3 and Ba0.99Er0.01TiO3 ceramics were carefully investigated. The temperature and frequency dependences of the dielectric properties of erbium doped BaTiO3 ceramics were measured in the 25–225 °C and 100 Hz to 10 MHz ranges, respectively. From this study, a dielectric anomaly in the ferroelectric–paraelectric phase transition of the Ba0.99Er0.01TiO3 ceramic was observed. The features of the samples phase transition were analysed by using Curie–Weiss, Santos–Eiras’ and order parameter local phenomenological models. In the BaTiO3 system, all models showed a normal phase transition, while was not possible to establish the character of the phase transition in the Ba0.99Er0.01TiO3 system. The relaxation parameters of conductive processes for the study ferroelectric materials, analysed in the time domain, did not show any influence on the ferroelectric–paraelectric phase transition. Finally, it was demonstrated that the anomaly observed on the phase transition of the erbium doped BaTiO3 ceramics is associated with the processes that results in the PTCR effect.
Phase transition and PTCR effect in erbium doped BT ceramics
Energy Technology Data Exchange (ETDEWEB)
Leyet, Y. [Departamento de Fisica, Facultad de Ciencias Naturales, Universidad de Oriente, C.P. 90500 Santiago de Cuba (Cuba); Instituto Federal de Educacao Ciencia e Tecnologia (IFAM), Av. 7 de Setembro 1975, Centro, Manaus 69020-120, AM (Brazil); Pena, R.; Zulueta, Y. [Departamento de Fisica, Facultad de Ciencias Naturales, Universidad de Oriente, C.P. 90500 Santiago de Cuba (Cuba); Guerrero, F. [Departamento de Fisica, Facultad de Ciencias Naturales, Universidad de Oriente, C.P. 90500 Santiago de Cuba (Cuba); CESI, Universidade do Estado do Amazonas, Ave Mario Andreaza, Amazonas (Brazil); Anglada-Rivera, J. [CESI, Universidade do Estado do Amazonas, Ave Mario Andreaza, Amazonas (Brazil); Romaguera, Y. [INESC TEC, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Perez de la Cruz, J., E-mail: jcruz@inescporto.pt [INESC TEC, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal)
2012-06-25
Highlights: Black-Right-Pointing-Pointer Erbium influence the dielectric response BaTiO{sub 3} ceramics. Black-Right-Pointing-Pointer Features of the phase transition are not explained by phenomenological models. Black-Right-Pointing-Pointer Relaxation parameters do not show influence on ferroelectric-paraelectric phase transition. Black-Right-Pointing-Pointer Dielectric anomaly on BET phase transition is associated with the PTCR effect. - Abstract: In this work the dielectric behaviour and main features of the phase transition of BaTiO{sub 3} and Ba{sub 0.99}Er{sub 0.01}TiO{sub 3} ceramics were carefully investigated. The temperature and frequency dependences of the dielectric properties of erbium doped BaTiO{sub 3} ceramics were measured in the 25-225 Degree-Sign C and 100 Hz to 10 MHz ranges, respectively. From this study, a dielectric anomaly in the ferroelectric-paraelectric phase transition of the Ba{sub 0.99}Er{sub 0.01}TiO{sub 3} ceramic was observed. The features of the samples phase transition were analysed by using Curie-Weiss, Santos-Eiras' and order parameter local phenomenological models. In the BaTiO{sub 3} system, all models showed a normal phase transition, while was not possible to establish the character of the phase transition in the Ba{sub 0.99}Er{sub 0.01}TiO{sub 3} system. The relaxation parameters of conductive processes for the study ferroelectric materials, analysed in the time domain, did not show any influence on the ferroelectric-paraelectric phase transition. Finally, it was demonstrated that the anomaly observed on the phase transition of the erbium doped BaTiO{sub 3} ceramics is associated with the processes that results in the PTCR effect.
International Nuclear Information System (INIS)
Phase behavior, structure and molecular dynamics of a chiral liquid crystalline compound, which exhibits SmG*, SmJ*, SmF*, SmI*, SmC*, SmA*, N* and BP*, have been investigated. Observed optical textures, synchrotron radiation diffraction data and frequency dependent dielectric spectroscopic study clearly depict the temperature evolution of the different hexatic smectic phases along with cholesteric and blue phase in a single compound. In hexatic phases dielectric absorption spectra show one low frequency relaxation process, related to the phase fluctuation of the bond orientational order, and one high frequency process related to amplitude fluctuation of the bond orientational order coupled with the polarization and tilt of the molecules. Goldstone and soft mode relaxation processes are detected, respectively, in SmC* and SmA* phases. (paper)
Symmetry origin of the phase transitions and phase separation in manganites at low doping
Wang, ZD; Zhong, F
1999-01-01
We analyze the symmetry changes of paramagnetic to A-type antiferromagnetic and to ferromagnetic phase transitions in undoped and moderately doped LaMnO 3, respectively. We show that in orthorhombic-distorted perovskite manganites the phase separation at low doping is associated with the noncollinear nature of the magnetic orders permitted by symmetry. A simple model for the competition between the two phase transitions is put forward within the framework of the Landau theory of phase transit...
Kurka, Ondřej; Kučera, Lukáš; Bednář, Petr
2016-07-01
cis-Itraconazole is a chiral antifungal drug administered as a racemate. The knowledge of properties of individual cis-itraconazole stereoisomers is vital information for medicine and biosciences as different stereoisomers of cis-itraconazole may possess different affinity to certain biological pathways in the human body. For this purpose, either chiral synthesis of enantiomers or chiral separation of racemate can be used. This paper presents a two-step high-performance liquid chromatography approach for the semipreparative isolation of four stereoisomers (two enantiomeric pairs) of itraconazole using polysaccharide stationary phases and volatile organic mobile phases without additives in isocratic mode. The approach used involves the separation of the racemate into three fractions (i.e. two pure stereoisomers and one mixed fraction containing the remaining two stereoisomers) in the first run and consequent separation of the collected mixed fraction in the second one. For this purpose, combination of cellulose tris-(4-methylbenzoate) and cellulose tris-(3,5-dimehylphenylcarbamate) columns with complementary selectivity for cis-itraconazole provided full separation of all four stereoisomers (with purity of each isomer > 97%). The stereoisomers were collected, their optical rotation determined and their identity confirmed based on the results of a previously published study. Pure separated stereoisomers are subjected to further biological studies. PMID:27240968
Energy Technology Data Exchange (ETDEWEB)
Hemine, J. [Laboratoire de Physique de la Matiere Condensee, Universite Hassan II, F.S.T. Mohammedia BP 146 (Morocco)]. E-mail: hemine1@yahoo.fr; Daoudi, A. [Laboratoire de Thermophysique de la Matiere, Universite du Littoral-Cote d' Opale, 145, Avenue Maurice Schumann, 59 140 Dunkerque, France. (France); Legrand, C. [Laboratoire d' Etude des Materiaux et des Composants pour l' Electronique, EA 2601, Universite du Littoral-Cote d' Opale BP 717, Calais (France); Isaert, N. [Laboratoire de Dynamique et Structures des Materiaux Moleculaires, URA No 801, Universite de Lille 1, 59655 Villeneuve d' Ascq (France); El kaaouachi, A. [Laboratoire de Physique de la Matiere Condensee, Faculte des Sciences Ibnou Zohr, BP 28/S 80000, Agadir (Morocco); Nguyen, H.T. [Centre de Recherche Paul Pascal, Universite de Bordeaux 1, 33600 Pessac (France)
2007-10-01
Electro-optical and dielectric investigations of a ferroelectric liquid crystal (FLC) exhibiting the chiral smectic C phase (SmC*) have been carried out as a function of temperature. These experimental studies have been applied to a new FLC having high spontaneous polarization and relaxation frequency. The Goldstone relaxation mode was studied from the dielectric response of FLC cells without DC bias voltage. The rotational viscosity corresponding to molecular motion in the SmC* phase was also determined from both electro-optical and dielectric measurements. An Arrhenius-type behaviour of the rotational viscosity was obtained and the corresponding activation energies were evaluated.
Mishra, H
2001-01-01
We discuss in this note simultaneous existence of chiral symmetry breaking and color superconductivity at finite temperature and density in a Nambu-Jona-Lasinio type model. The methodology involves an explicit construction of a variational ground state and minimisation of the thermodynamic potential. There exist nontrivial solutions to the gap equations at finite densities with both quark-antiquark as well as diquark condensates for the 'ground' state. However, such a phase is thermodynamically unstable with the pressure being negative in this region. We also compute the equation of state, and obtain the structure of the phase diagram in the model.
Kanemura, Shinya; Shindou, Tetsuo
2011-01-01
We investigate the one-loop effect of new charged scalar bosons on the Higgs potential at finite temperatures in the supersymmetric standard model with four Higgs doublet chiral superfields as well as a pair of charged singlet chiral superfields. In this model, the mass of the lightest Higgs boson $h$ is determined only by the D-term in the Higgs potential at the tree-level, while the triple Higgs boson coupling for $hhh$ can receive a significant radiative correction due to nondecoupling one-loop contributions of the additional charged scalar bosons. We find that the same nondecoupling mechanism can also contribute to realize stronger first order electroweak phase transition than that in the minimal supersymmetric standard model, which is definitely required for a successful scenario of electroweak baryogenesis. Therefore, this model can be a new candidate for a model in which the baryon asymmetry of the Universe is explained at the electroweak scale.
Fiorilla, Salvatore; Weise, Wolfram
2011-01-01
We calculate the equation of state of nuclear matter for arbitrary isospin-asymmetry up to three loop order in the free energy density in the framework of in-medium chiral perturbation theory. In our approach 1\\pi- and 2\\pi-exchange dynamics with the inclusion of the \\Delta-isobar excitation as an explicit degree of freedom, corresponding to the long- and intermediate-range correlations, are treated explicitly. Few contact terms fixed to reproduce selected known properties of nuclear matter encode the short-distance physics. Two-body as well as three-body forces are systematically included. We find a critical temperature of about 15 MeV for symmetric nuclear matter. We investigate the dependence of the liquid-gas first-order phase transition on isospin-asymmetry. In the same chiral framework we calculate the chiral condensate of isospin-symmetric nuclear matter at finite temperatures. The contribution of the \\Delta-isobar excitation is essential for stabilizing the condensate. As a result, we find no indicati...
Nature of chiral spin liquids on the kagome lattice
Wietek, Alexander; Sterdyniak, Antoine; Läuchli, Andreas M.
2015-09-01
We investigate the stability and the nature of the chiral spin liquids which were recently uncovered in extended Heisenberg models on the kagome lattice. Using a Gutzwiller projected wave function approach, i.e., a parton construction, we obtain large overlaps with ground states of these extended Heisenberg models. We further suggest that the appearance of the chiral spin liquid in the time-reversal invariant case is linked to a classical transition line between two magnetically ordered phases.
Micellar structures in lyotropic liquid crystals and phase transitions
Saupe, A.; Xu, S. Y.; Plumley, Sulakshana; Zhu, Y. K.; Photinos, P.
1991-05-01
The formation of micellar nematics is discussed with emphasis on the transitions between nematic phases and nematic-smectic transitions. Phase diagrams for MTAB/l-decanol/D,O systems show a direct transition between uniaxial nematics. Electrical conductivity and birefringence measurements on a mixture of sodium decylsulfate. 1-decanol, D,O demonstrate, on the other hand, the existence of a biaxial nemantic range that separates the Uniaxial nematics. On a mixture of cesium perflouroctanoate and H 2O the electrical conductivity and rotational viscosity are used to discuss the relevant features of nematic-lamellar-smectic transitions. The formation of elongated ribbon-like micelles at the nematic-smectic transition is suggested. Transitions between different nematic phases in the MTAB system may be connected with a structural change from long micelles with a fairly circular cross section to similar micelles with a more elliptical cross section.
Lin, Xianqing; Ni, Jun
2016-08-01
First-principles calculations have been performed to study the energetic, electronic, and magnetic properties of substitutional 3d transition metal dopants in monoclinic transition metal dichalcogenides (TMDs) as topological insulators ( 1 T ' - MX 2 with M = (Mo, W) and X = (S, Se)). We find various favorite features in these doped systems to introduce magnetism and other desirable electronic properties: (i) The Mn embedded monoclinic TMDs are magnetic, and the doped 1 T ' - MoS 2 still maintains the semiconducting character with high concentration of Mn, while an electronic phase transition occurs in other Mn doped monoclinic TMDs with an increasing concentration of Mn. Two Mn dopants prefer the ferromagnetic coupling except for substitution of the nearest Mo atoms in 1 T ' - MoS 2 , and the strength of exchange interaction shows anisotropic behavior with dopants along one Mo zigzag chain having much stronger coupling. (ii) The substitutional V is a promising hole dopant, which causes little change to the energy dispersion around the conduction and valence band edges in most systems. In contrast, parts of the conduction band drop for the electron dopants Co and Ni due to the large structural distortion. Moreover, closing band gaps of the host materials are observed with increasing carrier concentration. (iii) Single Fe dopant has a magnetic moment, but it also dopes electrons. When two Fe dopants have a small distance, the systems turn into nonmagnetic semiconductors. (iv) The formation energies of all dopants are much lower than those in hexagonal TMDs and are all negative in certain growth conditions, suggesting possible realization of the predicted magnetism, electronic phase transitions as well as carrier doping in 1 T ' - MX 2 based topological devices.
Primordial Magnetic Fields from Cosmological First Order Phase Transitions
Sigl, G; Jedamzik, K; Sigl, Guenter; Olinto, Angela; Jedamzik, Karsten
1996-01-01
We give an improved estimate of primordial magnetic fields generated during cosmological first order phase transitions. We examine the charge distribution at the nucleated bubble wall and its dynamics. We consider instabilities on the bubble walls developing during the phase transition. It is found that damping of these instabilities due to viscosity and heat conductivity caused by particle diffusion can be important in the QCD phase transition, but is probably negligible in the electroweak transition. We show how such instabilities together with the surface charge densities on bubble walls excite magnetic fields within a certain range of wavelengths. We discuss how these magnetic seed fields may be amplified by MHD effects in the turbulent fluid. The strength and spectrum of the primordial magnetic field at the present time for the cases where this mechanism was operative during the electroweak or the QCD phase transition are estimated. On a 10 Mpc comoving scale, field strengths of the order 10**(-29) G for...
Dynamics of Phase Transitions by Hysteresis Methods I
Berg, B A; Meyer-Ortmanns, H; Velytsky, A; Berg, Bernd A.; Heller, Urs M.; Meyer-Ortmanns, Hildegard; Velytsky, Alexander
2004-01-01
In studies of the QCD deconfining phase transition or crossover by means of heavy ion experiments, one ought to be concerned about non-equilibrium effects due to heating and cooling of the system. Motivated by this, we look at hysteresis methods to study the dynamics of phase transitions. Our systems are temperature driven through the phase transition using updating procedures in the Glauber universality class. Hysteresis calculations are presented for a number of observables, including the (internal) energy, properties of Fortuin-Kasteleyn clusters and structure functions. We test the methods for 2d Potts models, which provide a rich collection of phase transitions with a number of rigorously known properties. Comparing with equilibrium configurations we find a scenario where the dynamics of the transition leads to a spinodal decomposition which dominates the statistical properties of the configurations. One may expect an enhancement of low energy gluon production due to spinodal decomposition of the Polyako...
Deviatoric stress-induced phase transitions in diamantane
Energy Technology Data Exchange (ETDEWEB)
Yang, Fan; Lin, Yu [Geological and Environmental Sciences, Stanford University, Stanford, California 94305 (United States); Dahl, Jeremy E. P.; Carlson, Robert M. K. [Stanford Institute for Materials and Energy Science, Stanford, California 94305 (United States); Mao, Wendy L. [Geological and Environmental Sciences, Stanford University, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Science, Stanford, California 94305 (United States); Photon Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)
2014-10-21
The high-pressure behavior of diamantane was investigated using angle-dispersive synchrotron x-ray diffraction (XRD) and Raman spectroscopy in diamond anvil cells. Our experiments revealed that the structural transitions in diamantane were extremely sensitive to deviatoric stress. Under non-hydrostatic conditions, diamantane underwent a cubic (space group Pa3) to a monoclinic phase transition at below 0.15 GPa, the lowest pressure we were able to measure. Upon further compression to 3.5 GPa, this monoclinic phase transformed into another high-pressure monoclinic phase which persisted to 32 GPa, the highest pressure studied in our experiments. However, under more hydrostatic conditions using silicone oil as a pressure medium, the transition pressure to the first high-pressure monoclinic phase was elevated to 7–10 GPa, which coincided with the hydrostatic limit of silicone oil. In another experiment using helium as a pressure medium, no phase transitions were observed to the highest pressure we reached (13 GPa). In addition, large hysteresis and sluggish transition kinetics were observed upon decompression. Over the pressure range where phase transitions were confirmed by XRD, only continuous changes in the Raman spectra were observed. This suggests that these phase transitions are associated with unit cell distortions and modifications in molecular packing rather than the formation of new carbon-carbon bonds under pressure.
High-pressure phase transitions - Examples of classical predictability
Celebonovic, Vladan
1992-09-01
The applicability of the Savic and Kasanin (1962-1967) classical theory of dense matter to laboratory experiments requiring estimates of high-pressure phase transitions was examined by determining phase transition pressures for a set of 19 chemical substances (including elements, hydrocarbons, metal oxides, and salts) for which experimental data were available. A comparison between experimental and transition points and those predicted by the Savic-Kasanin theory showed that the theory can be used for estimating values of transition pressures. The results also support conclusions obtained in previous astronomical applications of the Savic-Kasanin theory.
Phase Transition Induced by Small Molecules in Confined Copolymer Films
Institute of Scientific and Technical Information of China (English)
ZHOU Ling
2007-01-01
We investigate the phase transition induced by small molecules in confined copolymer films by using density functional theory.It is found that the addition of small molecules can effectively promote the phase separation of copolymers.In a symmetric diblock copolymer film,the affinity and concentration of small molecules play an important role in the structure transjtions.The disordered-lamellar transitions lamellar-lamellar transitions and the re-entrant transitions of the same structures are observed.Our results have potential applications in the fabrication of new functional materials.
Phase-separation transitions in asymmetric lipid bilayers
Shimobayashi, Shunsuke F; Taniguchi, Takashi
2015-01-01
Morphological transitions of phase separation associated with the asymmetry of lipid composition were investigated using micrometer-sized vesicles of lipid bilayers made from a lipid mixture. The complete macro-phase-separated morphology undergoes a transition to a micro-phase-separation-like morphology via a lorate morphology as a metastable state. The transition leads to the emergence of monodisperse nanosized domains through repeated domain scission events. Moreover, we have numerically confirmed the transitions using the time-dependent Ginzburg-Landau model describing phase separation and the bending elastic membrane, which is quantitatively consistent with experimental results by fixing one free parameter. Our findings suggest that the local spontaneous curvature due to the asymmetric composition plays an essential role in the thermodynamic stabilization of micro-phase separation in lipid bilayers.
Photothermoelectric (PTE) Versus Photopyroelectric (PPE) Detection of Phase Transitions
Dadarlat, D.; Guilmeau, E.; Hadj Sahraoui, A.; Tudoran, C.; Surducan, V.; Bourgès, C.; Lemoine, P.
2016-05-01
The photopyroelectric (PPE) technique is one of the photothermal (PT) methods mostly used for phase transitions investigations. In this paper, we want to compare the PPE results with those obtained using another, recently developed PT method [the photothermoelectric (PTE) calorimetry] for the same purpose of detecting phase transitions. The well-known ferro-paraelectric phase transition of TGS, taking place at a convenient temperature (about 49 {}^{circ }hbox {C}), has been selected for demonstration. A comparison of the two PPE and PTE methods, both in the back detection configuration (in the special case of optically opaque sample and thermally thick regime for both sensors and sample) shows that they are equally suitable for phase transitions detection. Performing a proper calibration, the amplitude and phase of the signals can be used in order to obtain the critical behaviour of all sample's static and dynamic thermal parameters.
Zhang, Jingchuan; Lörscher, Christopher; Gu, Qiang; Klemm, Richard A.
2014-01-01
We calculate the temperature $T$ and angular $(\\theta,\\phi)$ dependence of the upper critical induction $B_{c2}(\\theta,\\phi,T)$ for parallel-spin superconductors with an axially symmetric $p$-wave pairing interaction pinned to the lattice and a dominant ellipsoidal Fermi surface (FS). For all FS anisotropies, the chiral Scharnberg-Klemm state $B_{c2}(\\theta,\\phi,T)$ exceeds that of the chiral Anderson-Brinkman-Morel state, and exhibits a kink at $\\theta=\\theta^{*}(T,\\phi)$, indicative of a fi...
Phase transitions in pure and dilute thin ferromagnetic films
Korneta, W.; Pytel, Z.
1983-10-01
The mean-field model of a thin ferromagnetic film where the nearest-neighbor exchange coupling in surface layers can be different from that inside the film is considered. The phase diagram, equations for the second-order phase-transition lines, and the spontaneous magnetization profiles near the phase transitions are given. It is shown that there is no extra-ordinary transition in a thin film. If the thickness of the film tends to infinity the well-known results for the mean-field model of a semi-infinite ferromagnet are obtained. The generalization for disordered dilute thin ferromagnetic films and semi-infinite ferromagnets is also given.
Superradiant phase transitions with three-level systems
Baksic, Alexandre; Ciuti, Cristiano
2013-01-01
We determine the phase diagram of $N$ identical three-level systems interacting with a single photonic mode in the thermodynamical limit ($N \\to \\infty$) by accounting for the so-called diamagnetic term and the inequalities imposed by the Thomas-Reich-Kuhn (TRK) oscillator strength sum rule. The key role of transitions between excited levels and the occurrence of first-order phase transitions is discussed. We show that, in contrast to two-level systems, in the three-level case the TRK inequalities do not always prevent a superradiant phase transition in presence of a diamagnetic term.
Role of multistability in the transition to chaotic phase synchronization
DEFF Research Database (Denmark)
Postnov, D.E.; Vadivasova, T.E.; Sosnovtseva, Olga;
1999-01-01
In this paper we describe the transition to phase synchronization for systems of coupled nonlinear oscillators that individually follow the Feigenbaum route to chaos. A nested structure of phase synchronized regions of different attractor families is observed. With this structure, the transition...... to nonsynchronous behavior is determined by the loss of stability for the most stable synchronous mode. It is shown that the appearance of hyperchaos and the transition from lag synchronization to phase synchronization are related to the merging of chaotic attractors from different families. Numerical examples...
Weakly First Order Cosmological Phase Transitions and Fermion Production
Gleiser, Marcello; Gleiser, Marcelo; Trodden, Mark
2001-01-01
We study weakly first order cosmological phase transitions in finite temperature field theories. Focusing on the standard electroweak theory and its minimal supersymmetric extension, we identify the regimes of Higgs masses for which the phase transition in these models proceeds by significant phase mixing and the coarsening of the subsequent domain network. This dynamics is distinct from that for strongly first order transitions, which proceed by the nucleation and propagation of critical bubbles. We describe how electroweak baryogenesis might take place in these models, explaining how our new picture can relax the sphaleron washout bound of traditional scenarios.
Wang, Rui; Qiao, Qian; Wang, Bin; Ding, Xiu-Huan; Zhang, Yi-Fu
2016-09-01
The quantum spin Hall (QSH) effect and the quantum anomalous Hall (QAH) effect in Lieb lattice are investigated in the presence of both Rashba spin-orbit coupling (SOC) and uniform exchange field. The Lieb lattice has a simple cubic symmetry, which is characterized by the single Dirac-cone per Brillouin zone and the middle flat band in the band structure. The intrinsic SOC is essentially needed to open the full energy gap in the bulk. The QSH effect could survive even in the presence of the exchange field. In terms of the first Chern number and the spin Chern number, we study the topological nature and the topological phase transition from the time-reversal symmetry broken QSH effect to the QAH effect. For Lieb lattice ribbons, the energy spectrum and the wave-function distributions are obtained numerically, where the helical edge states and the chiral edge states reveal the non-trivial topological QSH and QAH properties, respectively.
Theory of Coupled Phase Transitions: Phase Separation and Variation of Order Parameter
Zhong, Fan
1998-01-01
A simplified Ginzburg-Landau theory is presented to study generally a coupling of a first-order phase transition (FOPT) to a second-order phase transition (SOPT). We show analytically that, due to the coupling between the two phase transitions, the SOPT may exhibit a FOPT-like phase separation in which an ordered phase is separated from a disordered one. This phase separation results in a distinct behavior in the variation of the order parameter of the SOPT, namely, it is primarily the propor...
Directory of Open Access Journals (Sweden)
Wang Dao-Cai
2016-01-01
Full Text Available In the light of the chiral resolution mechanism and structures of brush-type CSP, a new chiral selector 4′-carboxyl-1′-ursolic methyl ester-3β-yl-benzoate has been prepared. Then the terpenoid chiral selector was covalently linked to 3-aminopropyl silica gel. Its structure identification data are provided by 1H NMR, MS and elementary analysis. The enantiodiscriminating capability of the brush-type CSP was evaluated by static adsorption experiment with methyl mandelate, aniline derivative of mandelic acid, benzoin and ibuprofen. Experimental results demonstrated that the chiral selector has selectivity, and the enantiomers of methyl mandelate and ibuprofen could be separated on the CSP, which indicated that the novel brush-type CSP possess a bright prospects for chiral separation potentially.
Phase sensitive quantum interference on forbidden transition in ladder scheme
Koganov, Gennady A
2014-01-01
A three level ladder system is analyzed and the coherence of initially electric-dipole forbidden transition is calculated. Due to the presence of two laser fields the initially dipole forbidden transition becomes dynamically permitted due to ac Stark effect. It is shown that such transitions exhibit quantum-interference-related phenomena, such as electromagnetically induced transparency, gain without inversion and enhanced refractive index. Gain and dispersion characteristics of such transitions strongly depend upon the relative phase between the driving and the probe fields. Unlike allowed transitions, gain/absorption behavior of ac-Stark allowed transitions exhibit antisymmetric feature on the Rabi sidebands. It is found that absorption/gain spectra possess extremely narrow sub-natural resonances on these ac Stark allowed forbidden transitions. An interesting finding is simultaneous existence of gain and negative dispersion at Autler-Townes transition which may lead to both reduction of the group velocity a...
Which Chiral Symmetry is Restored in High Temperature QCD?
Bernard, C W; DeTar, C E; Gottlieb, S; Heller, U M; Hetrick, J E; Rummukainen, K; Sugar, R; Toussaint, D; Wingate, M; Bernard, Claude; Blum, Tom; Tar, Carleton De; Gottlieb, Steven; Heller, Urs M.; Hetrick, James E.; Wingate, Matthew
1996-01-01
Sigma models for the high temperature phase transition in quantum chromodynamics (QCD) suggest that at high temperature the SU(N_f) x SU(N_f) chiral symmetry becomes exact, but the anomalous axial U(1) symmetry need not be restored. In numerical lattice simulations, traditional methods for detecting symmetry restoration have sought multiplets in the screening mass spectrum. However, these methods were imprecise and the results, so far, incomplete. With improved statistics and methodology, we are now able to offer evidence for a restoration of the SU(2) x SU(2) chiral symmetry just above the crossover, but not of the axial U(1) chiral symmetry.
A strictly hyperbolic equilibrium phase transition model
Energy Technology Data Exchange (ETDEWEB)
Allaire, G [Ecole Polytech, CNRS, CMAP, F-91128 Palaiseau (France); Faccanoni, G; Kokh, S. [CEA Saclay, DEN, DANS, DM2S, F-91191 Gif Sur Yvette, (France)
2007-01-15
This Note is concerned with the strict hyperbolicity of the compressible Euler equations equipped with an equation of state that describes the thermodynamical equilibrium between the liquid phase and the vapor phase of a fluid. The proof is valid for a very wide class of fluids. The argument only relies on smoothness assumptions and on the classical thermodynamical stability assumptions, that requires a definite negative Hessian matrix for each phase entropy as a function of the specific volume and internal energy. (authors)
Effect of dimensionality on vapor-liquid phase transition
Singh, Sudhir Kumar
2014-04-01
Dimensionality play significant role on `phase transitions'. Fluids in macroscopic confinement (bulk or 3-Dimensional, 3D) do not show significant changes in their phase transition properties with extent of confinement, since the number of molecules away from the surrounding surfaces is astronomically higher than the number of molecules in close proximity of the confining surfaces. In microscopic confinement (quasi 3D to quasi-2D), however, the number of molecules away from the close proximity of the surface is not as high as is the case with macroscopic (3D) confinement. Hence, under the same thermodynamic conditions `phase transition' properties at microscopic confinement may not remain the same as the macroscopic or 3D values. Phase transitions at extremely small scale become very sensitive to the dimensions as well as the surface characteristics of the system. In this work our investigations reveal the effect of dimensionality on the phase transition from 3D to quasi-2D to 2D behavior. We have used grand canonical transition matrix Monte Carlo simulation to understand the vapor-liquid phase transitions from 3D to quasi-2D behavior. Such studies can be helpful in understanding and controlling the fluid film behaviour confined between solid surfaces of few molecular diameters, for example, in lubrication applications.
Kanie, Osamu; Shioiri, Yuki; Ogata, Koji; Uchida, Waka; Daikoku, Shusaku; Suzuki, Katsuhiko; Nakamura, Shinichiro; Ito, Yukishige
2016-01-01
Defining chiral centres is addressed by introducing a pair of chiral auxiliary groups. Ions of diastereomeric pairs of molecules could be distinguished utilising energy-resolved mass spectrometry, and the applicability of the method to a series of compounds carrying amine, carboxylic acid, alcohol, and all the amino acids was verified. The method was further strengthened by distinguishing diastereomeric ions that did not undergo fragmentation. Mass spectrometric evaluation of the dissociation process of adducted sodium cations from the diastereomeric precursors agreed with the theoretical calculations, indicating the potential usefulness of the method for the determination of absolute configurations. PMID:27040078
Peng, Yangfeng; He, Quan Sophia; Cai, Jiang
2016-01-01
Enantiomeric separation of citalopram (CIT) was developed using a reversed phase HPLC (RP-HPLC) with sulfobutylether-β-cyclodextrin (SBE-β-CD) as a chiral mobile phase additive. The effects of the pH value of aqueous buffer, concentration of chiral additive, composition of mobile phase, and column temperature on the enantioseparation of CIT were investigated on the Hedera ODS-2 C18 column (250 mm × 4.6 mm × 5.0 um). A satisfactory resolution was achieved at 25°C using a mobile phase consisting of a mixture of aqueous buffer (pH of 2.5, 5 mM sodium dihydrogen phosphate, and 12 mM SBE-β-CD), methanol, and acetonitrile with a volumetric ratio of 21 : 3 : 1 and flow rate of 1.0 mL/min. This analytical method was evaluated by examining the precision (lower than 3.0%), linearity (regression coefficients close to 1), limit of detection (0.070 µg/mL for (R)-CIT and 0.076 µg/mL for (S)-CIT), and limit of quantitation (0.235 µg/mL for (R)-CIT and 0.254 µg/mL for (S)-CIT). PMID:26880921
Directory of Open Access Journals (Sweden)
Yangfeng Peng
2016-01-01
Full Text Available Enantiomeric separation of citalopram (CIT was developed using a reversed phase HPLC (RP-HPLC with sulfobutylether-β-cyclodextrin (SBE-β-CD as a chiral mobile phase additive. The effects of the pH value of aqueous buffer, concentration of chiral additive, composition of mobile phase, and column temperature on the enantioseparation of CIT were investigated on the Hedera ODS-2 C18 column (250 mm × 4.6 mm × 5.0 um. A satisfactory resolution was achieved at 25°C using a mobile phase consisting of a mixture of aqueous buffer (pH of 2.5, 5 mM sodium dihydrogen phosphate, and 12 mM SBE-β-CD, methanol, and acetonitrile with a volumetric ratio of 21 : 3 : 1 and flow rate of 1.0 mL/min. This analytical method was evaluated by examining the precision (lower than 3.0%, linearity (regression coefficients close to 1, limit of detection (0.070 µg/mL for (R-CIT and 0.076 µg/mL for (S-CIT, and limit of quantitation (0.235 µg/mL for (R-CIT and 0.254 µg/mL for (S-CIT.
Energy Technology Data Exchange (ETDEWEB)
Mustonen, K.; Laiho, P.; Kaskela, A.; Zhu, Z.; Reynaud, O.; Houbenov, N.; Tian, Y.; Jiang, H.; Kauppinen, E. I., E-mail: esko.kauppinen@aalto.fi [Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto (Finland); Susi, T. [Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna (Austria); Nasibulin, A. G. [Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto (Finland); Skolkovo Institute of Science and Technology, Nobel str. 3, 143026 (Russian Federation); Saint-Petersburg State Polytechnical University, 29 Polytechniheskaya st., St. Petersburg, 195251 (Russian Federation)
2015-07-06
We present a floating catalyst synthesis route for individual, i.e., non-bundled, small diameter single-walled carbon nanotubes (SWCNTs) with a narrow chiral angle distribution peaking at high chiralities near the armchair species. An ex situ spark discharge generator was used to form iron particles with geometric number mean diameters of 3–4 nm and fed into a laminar flow chemical vapour deposition reactor for the continuous synthesis of long and high-quality SWCNTs from ambient pressure carbon monoxide. The intensity ratio of G/D peaks in Raman spectra up to 48 and mean tube lengths up to 4 μm were observed. The chiral distributions, as directly determined by electron diffraction in the transmission electron microscope, clustered around the (n,m) indices (7,6), (8,6), (8,7), and (9,6), with up to 70% of tubes having chiral angles over 20°. The mean diameter of SWCNTs was reduced from 1.10 to 1.04 nm by decreasing the growth temperature from 880 to 750 °C, which simultaneously increased the fraction of semiconducting tubes from 67% to 80%. Limiting the nanotube gas phase number concentration to ∼10{sup 5 }cm{sup −3} prevented nanotube bundle formation that is due to collisions induced by Brownian diffusion. Up to 80% of 500 as-deposited tubes observed by atomic force and transmission electron microscopy were individual. Transparent conducting films deposited from these SWCNTs exhibited record low sheet resistances of 63 Ω/□ at 90% transparency for 550 nm light.
Discontinuous structural phase transition of liquid metal and alloys (2)
International Nuclear Information System (INIS)
The diameter (df) 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
Phase transition in extended thermodynamic phase space and charged Horava-Lifshitz black holes
Poshteh, Mohammad Bagher Jahani; Riazi, Nematollah
2016-01-01
For charged black holes in Horava-Lifshitz gravity, it is shown that a second order phase transition takes place in extended phase space. We study the behavior of specific heat and free energy at the point of transition in canonical and grand canonical ensembles and show that the black hole falls into a state which is locally and globally stable. We relate the second order nature of phase transition to the fact that the phase transition occurs at a sharp temperature and not over a temperature...
Zhang, L; Gedicke, K; Kuznetsov, M A; Staroverov, S M; Seidel-Morgenstern, A
2007-08-24
Recently a new chiral stationary phase (CSP) was introduced, based on the immobilization of the macrocyclic glycopeptide eremomycin to epoxy-activated silica. The application of this new CSP to preparative enantioseparation using simulated moving bed (SMB) chromatography will be presented. MeOH-H(2)O (0.1M NaH(2)PO(4))=20/80 (v/v) was used as the mobile phase to separate the enantiomers of methionine. Successful separation was realized providing productivities around 15 g(product)/l(stat)/h for both l and d-methionine under nonlinear conditions. In such delicate continuous chromatographic separation processes, besides productivity, the long-term stability of the applied stationary phases is of importance. Column to column fluctuations were negligible and long-term stability of the preparative stationary phase was satisfactory according to the results of perturbation experiments performed before and after long-term SMB runs. PMID:17482626
Viscoelastic modes in chiral liquid crystals
Indian Academy of Sciences (India)
K A Suresh
2003-08-01
Viscoelastic properties of liquid crystals are very important for applications like display technology. However, there are not many direct techniques to study them. In this review, we describe our studies on the viscoelastic modes of some chiral liquid crystals using dynamic light scattering. We discuss viscoelastic modes corresponding to the C director ﬂuctuations in the chiral smectic C phase and the behaviour of the Goldstone-mode near the chiral smectic C–smectic A phase transition. In cholesteric liquid crystals, we consider the director ﬂuctuations in a wavevector range comparable to the inverse pitch of the cholesteric. Here, the study of the scattered light in the vicinity of the Bragg reﬂection using a novel geometry will be presented.
One-dimensional caricature of phase transition
Schonmann, Roberto H.; Tanaka, Nelson I.
1990-10-01
In the limit as the volume grows and the temperature vanishes, it is shown that the one-dimensional nearest neighbor ferromagnetic Ising model presents a sharp transition between two different regimes. Fluctuations are studied in one of these regimes and also in the critical case.
Statistical Physics and Dynamical Systems: Models of Phase Transitions
Patwardhan, Ajay
2007-01-01
This paper explores the connection between dynamical system properties and statistical physics of ensembles of such systems. Simple models are used to give novel phase transitions; particularly for finite N particle systems with many physically interesting examples.
Character of. pi. -condensate phase transition at finite temperature
Energy Technology Data Exchange (ETDEWEB)
Voskresenskii, D.N.; Mishustin, I.N.
1978-10-05
The results of analytic calculations of the critical temperature of pion condensation are presented. It follows from these results, in particular, that at sufficiently high temperature the pion condensation proceeds like a first-order phase transition.
Foundations of Statistical Mechanics and Theory of Phase Transition
Belokolos, E D
1997-01-01
A new formulation of statistical mechanics is put forward according to which a random variable characterizing a macroscopic body is postulated to be infinitely divisible. It leads to a parametric representation of partition function of an arbitrary macroscopic body, a possibility to describe a macroscopic body under excitation by a gas of some elementary quasiparticles etc. A phase transition is defined as such a state of a macroscopic body that its random variable is stable in sense of Lévy. From this definition it follows by deduction all general properties of phase transitions: existence of the renormalization semigroup, the singularity classification for thermodynamic functions, the phase transition universality and universality classes. On this basis we has also built a 2-parameter scaling theory of phase transitions, a thermodynamic function for the Ising model etc.
Dynamical symmetries and causality in non-equilibrium phase transitions
Henkel, Malte
2015-01-01
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.
Integrability and Quantum Phase Transitions in Interacting Boson Models
Dukelsky, J; García-Ramos, J E; Pittel, S
2003-01-01
The exact solution of the boson pairing hamiltonian given by Richardson in the sixties is used to study the phenomena of level crossings and quantum phase transitions in the integrable regions of the sd and sdg interacting boson models.
Gravitational waves from a very strong electroweak phase transition
Leitao, Leonardo
2015-01-01
We investigate the production of a stochastic background of gravitational waves in the electroweak phase transition. We consider a few extensions of the Standard Model which can give very strongly first-order phase transitions. We concentrate on the possibility that the phase transition fronts either propagate as detonations or run away. We compute the bubble wall velocity taking into account the friction and hydrodynamics due to the presence of the plasma, and we track the development of the phase transition up to the percolation time. We calculate the contribution to the gravitational wave spectrum from 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. The sound waves are generally the strongest source. Since this mechanism is diminished in the presence of runaway walls, the models with the best prospects of detection at...
Behavior of the Lyapunov Exponent and Phase Transition in Nuclei
Institute of Scientific and Technical Information of China (English)
WANG Nan; WU Xi-Zhen; LI Zhu-Xia; WANG Ning; ZHUO Yi-Zhong; SUN Xiu-Quan
2000-01-01
Based on the quantum molecular dynamics model, we investigate the dynamical behaviors of the excited nuclear system to simulate the latter stage of heavy ion reactions, which associate with a liquid-gas phase transition. We try to search a microscopic way to describe the phase transition in realnuclei. The Lyapunov exponent is employed and examined for our purpose. We find out that the Lyapunov exponent is one of good microscopic quantities to describe the phase transition in hot nuclei. Coulomb potential and the finite size effect may give a strong influence on the critical temperature. However, the collision term plays a minor role in the process of the liquid-gas phase transition in finite systems.
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.
Lifshitz transitions in magnetic phases of the periodic Anderson model
International Nuclear Information System (INIS)
We investigate the reconstruction of a Fermi surface, which is called a Lifshitz transition, in magnetically ordered phases of the periodic Anderson model on a square lattice with a finite Coulomb interaction between f electrons. We apply the variational Monte Carlo method to the model by using the Gutzwiller wavefunctions for the paramagnetic, antiferromagnetic, ferromagnetic, and charge-density-wave states. We find that an antiferromagnetic phase is realized around half-filling and a ferromagnetic phase is realized when the system is far away from half-filling. In both magnetic phases, Lifshitz transitions take place. By analyzing the electronic states, we conclude that the Lifshitz transitions to large ordered-moment states can be regarded as itinerant-localized transitions of the f electrons. (author)
Quantum phase transitions in the interacting boson model
Cejnar, Pavel
2008-01-01
This review is focused on various properties of quantum phase transitions (QPTs) in the Interacting Boson Model (IBM) of nuclear structure. The model in its infinite-size limit exhibits shape-phase transitions between spherical, deformed prolate, and deformed oblate forms of the ground state. Finite-size precursors of such behavior are verified by robust variations of nuclear properties (nuclear masses, excitation energies, transition probabilities for low lying levels) across the chart of nuclides. Simultaneously, the model serves as a theoretical laboratory for studying diverse general features of QPTs in interacting many-body systems, which differ in many respects from lattice models of solid-state physics. We outline the most important fields of the present interest: (a) The coexistence of first- and second-order phase transitions supports studies related to the microscopic origin of the QPT phenomena. (b) The competing quantum phases are characterized by specific dynamical symmetries and novel symmetry r...
Lifshitz Transitions in Magnetic Phases of the Periodic Anderson Model
Kubo, Katsunori
2015-09-01
We investigate the reconstruction of a Fermi surface, which is called a Lifshitz transition, in magnetically ordered phases of the periodic Anderson model on a square lattice with a finite Coulomb interaction between f electrons. We apply the variational Monte Carlo method to the model by using the Gutzwiller wavefunctions for the paramagnetic, antiferromagnetic, ferromagnetic, and charge-density-wave states. We find that an antiferromagnetic phase is realized around half-filling and a ferromagnetic phase is realized when the system is far away from half-filling. In both magnetic phases, Lifshitz transitions take place. By analyzing the electronic states, we conclude that the Lifshitz transitions to large ordered-moment states can be regarded as itinerant-localized transitions of the f electrons.
Research for the energy turnaround. Phase transitions actively shape. Contributions
International Nuclear Information System (INIS)
The Annual Conference 2014 of the Renewable Energy Research Association was held in Berlin on 6 and 7 November 2014. This book documents the contributions of the conference on research for the energy turnaround, phase transitions actively shape. After an introduction and two contributions to the political framework, the contributions to the economic phases of the energy transition, the phase of the current turn, the phases of social energy revolution, the stages of heat turnaround (Waermewende), and the stages of the mobility turn deal with the stages of development of the energy system. Finally, the Research Association Renewable Energy is briefly presented.
Phase Transitions in a Forest-Fire Model
Clar, Siegfried; Schenk, Klaus; Schwabl, Franz
1997-01-01
We investigate a forest-fire model with the density of empty sites as control parameter. The model exhibits three phases, separated by one first-order phase transition and one 'mixed' phase transition which shows critical behavior on only one side and hysteresis. The critical behavior is found to be that of the self-organized critical forest-fire model [B. Drossel and F. Schwabl, Phys. Rev. Lett. 69, 1629 (1992)], whereas in the adjacent phase one finds the spiral waves of the Bak et al. fore...
Probing phase transitions of vortex matter by Josephson plasma resonance
International Nuclear Information System (INIS)
The Josephson plasma resonance is the most powerful means to study the vortex state in high-Tc superconductors. In this paper we report the detailed and quantitative study of the interlayer quantum phase coherence in the vortex liquid, Bragg glass and vortex glass phases of Bi2Sr2CaCu2O8+δ by the Josephson plasma resonance. We also provide a quantitative discussion on the nature of the phase transitions among these vortex phases. (author)
Phase transition of bismuth telluride thin films grown by MBE
DEFF Research Database (Denmark)
Fülöp, Attila; Song, Yuxin; Charpentier, Sophie;
2014-01-01
A previously unreported phase transition between Bi2Te3 and Bi4Te3 in bismuth telluride grown by molecular beam epitaxy is recorded via XRD, AFM, and SIMS observations. This transition is found to be related to the Te/Bi beam equivalent pressure (BEP) ratio. BEP ratios below 17 favor the formatio...
Phase transition in L-alaninium oxalate by photoacoustics
Indian Academy of Sciences (India)
M Sivabarathy; S Natarajan; S K Ramakrishnan; K Ramachandran
2004-10-01
Phase transition in L-alaninium oxalate is studied by using TG, DTA and photoacoustic spectroscopy. A sharp transition at 378 K by photoacoustics is observed whereas at the same temperature the endothermic energy change observed by TG and DTA is not very sharp. This is discussed in detail with reference to the other known data for the organic crystals.
Ab initio theory of helix <-> coil phase transition
DEFF Research Database (Denmark)
Yakubovich, Alexander V.; Solov'yov, Ilia; Solov'yov, Andrey V.;
2008-01-01
In this paper, we suggest a theoretical method based on the statistical mechanics for treating the alpha-helix <-> random coil transition in alanine polypeptides. We consider this process as a first-order phase transition and develop a theory which is free of model parameters and is based solely ...
Quantum Shape-Phase Transitions in Finite Nuclei
Leviatan, A
2007-01-01
Quantum shape-phase transitions in finite nuclei are considered in the framework of the interacting boson model. Critical-point Hamiltonians for first- and second-order transitions are identified by resolving them into intrinsic and collective parts. Suitable wave functions and finite-N estimates for observables at the critical-points are derived.
On the theory of phase transitions in polypeptides
DEFF Research Database (Denmark)
Yakubovich, Alexander V.; Solov'yov, Ilia; Solov'yov, Andrey V.;
2008-01-01
We suggest a theoretical method based on the statistical mechanics for treating the alpha-helix random coil transition in polypeptides. This process is considered as a first-order-like phase transition. The developed theory is free of model parameters and is based solely on fundamental physical...
Formation of Black Holes in First Order Phase Transitions
Khlopov, M. Yu.; R. V. Konoplich(Physics Dept.New York University, N.Y., USA); Rubin, S. G.; Sakharov, A. S.
1998-01-01
A new mechanism of black hole formation in a first order phase transition is proposed. In vacuum bubble collisions the interaction of bubble walls leads to the formation of nontrivial vacuum configuration. The consequent collapse of this vacuum configuration induces the black hole formation with high probability. Observational constraints on the spectrum of primordial black holes allow to obtain new nontrivial restrictions on parameters of inflation models with first order phase transitions.
Baryogenesis via leptonic CP-violating phase transition
Pascoli, Silvia; Zhou, Ye-Ling
2016-01-01
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 strong connections with low-energy neutrino experiments.
Effect of disorder on first-order phase transitions
Bellafard, Arash
2015-01-01
Disorder is an inevitable part of any condensed matter system and therefore its study has always been of great importance. The effect of quenched randomness on a system that exhibits a continuous phase transition in the absence of any impurity has been studied in the past and the results are relatively well understood. However, the effect of quenched randomness on \\emph{first-order} phase transitions is still not well understood. In this dissertation, we study the effect of quenched bond-rand...
An Analysis of Phase Transition in NK Landscapes
Culberson, J.; Gao, Y.
2011-01-01
In this paper, we analyze the decision version of the NK landscape model from the perspective of threshold phenomena and phase transitions under two random distributions, the uniform probability model and the fixed ratio model. For the uniform probability model, we prove that the phase transition is easy in the sense that there is a polynomial algorithm that can solve a random instance of the problem with the probability asymptotic to 1 as the problem size tends to infinity. For the fixed rat...
Effect of point defects and disorder on structural phase transitions
Energy Technology Data Exchange (ETDEWEB)
Toulouse, J.
1997-06-01
Since the beginning in 1986, the object of this project has been Structural Phase Transitions (SPT) in real as opposed to ideal materials. The first stage of the study has been centered around the role of Point Defects in SPT`s. Our intent was to use the previous knowledge we had acquired in the study of point defects in non-transforming insulators and apply it to the study of point defects in insulators undergoing phase transitions. In non-transforming insulators, point defects, in low concentrations, marginally affect the bulk properties of the host. It is nevertheless possible by resonance or relaxation methods to study the point defects themselves via their local motion. In transforming solids, however, close to a phase transition, atomic motions become correlated over very large distances; there, even point defects far removed from one another can undergo correlated motions which may strongly affect the transition behavior of the host. Near a structural transition, the elastic properties win be most strongly affected so as to either raise or decrease the transition temperature, prevent the transition from taking place altogether, or simply modify its nature and the microstructure or domain structure of the resulting phase. One of the well known practical examples is calcium-stabilized zirconia in which the high temperature cubic phase is stabilized at room temperature with greatly improved mechanical properties.
Quantum Phase Transitions and Dimerized Phases in Frustrated Spin Ladder
Institute of Scientific and Technical Information of China (English)
WEN Rui; LIU Guang-Hua; TIAN Guang-Shan
2011-01-01
In this paper, we study the phase diagram of a frustrated spin ladder model by applying the bosonization technique and the density-matrix renormalization-group (DMRG) algorithm. Effect of the intra-chain next-nearestneighbor (NNN) super-exchange interaction is investigated in detail and the order parameters are calculated to detect the emergence of the dimerized phases. We find that the intra-chain NNN interaction plays a key role in inducing dimerized phases.
Herzberg Circuit and Berry's Phase in Chirality-based Coded Qubit in a Triangular Triple Quantum Dot
Hsieh, Chang-Yu; Rene, Alexandre; Hawrylak, Pawel
2011-01-01
We present a theoretical proposal for the Herzberg circuit and controlled accumulation of Berry's phase in a chirality-based coded qubit in a triangular triple quantum dot molecule with one electron spin each. The qubit is encoded in the two degenerate states of a three spin complex with total spin $S=1/2$. Using a Hubbard and Heisenberg model the Herzberg circuit encircling the degeneracy point is realized by adiabatically tuning the successive on-site energies of quantum dots and tunnel cou...
Quark-Hadron Phase Transitions in Viscous Early Universe
Tawfik, A
2011-01-01
Based on hot big bang theory, the cosmological matter is conjectured to undergo QCD phase transition(s) to hadrons, when the universe was about $1-10 \\mu$s old. In the present work, we study the quark-hadron phase transition, by taking into account the effect of the bulk viscosity. We analyze the evolution of the quantities relevant for the physical description of the early universe, namely, the energy density $\\rho$, temperature $T$, Hubble parameter $H$ and scale factor $a$ before, during and after the phase transition. To study the cosmological dynamics and the time evolution we use both analytical and numerical methods. By assuming that the phase transition may be described by an effective nucleation theory (prompt {\\it first-order} phase transition), we also consider the case where the universe evolved through a mixed phase with a small initial supercooling and monotonically growing hadronic bubbles. The numerical estimation of the cosmological parameters, $a$ and $H$ for instance, makes it clear that th...
Phase transitions of a polymer threading a membrane coupled to coil-globule transitions
Matsuyama, Akihiko
2004-01-01
We theoretically study phase transitions of a polymer threading through a pore imbedded in a membrane. We focus on the coupling between a partition of the polymer segments through the membrane and a coil-globule transition of the single polymer chain. Based on the Flory model for collapse transitions of a polymer chain, we calculate the fraction of polymer segments and the expansion factor of a polymer coil on each side of the membrane. We predict a first-order phase transition of a polymer t...
Auditore, Roberta; Santagati, Natale A; Aturki, Zeineb; Fanali, Salvatore
2013-09-01
In this work, a novel polysaccharide-based chiral stationary phase, cellulose tris(4-chloro-3-methylphenylcarbamate), also called Sepapak 4 has been evaluated for the chiral separation of amlodipine (AML) and its two impurities. AML is a powerful vasodilatator drug used for the treatment of hypertension. Capillary columns of 100 μm id packed with the chiral stationary phase were used for both nano-LC and CEC experiments. The optimization of the mobile phase composed of ACN/water, (90:10, v/v) containing 15 mM ammonium borate pH 10.0 in nano-LC allowed the chiral separation of AML and the two impurities, but not in a single run. With the purpose to obtain the separation of the three pairs of enantiomers simultaneously, CEC analyses were performed in the same conditions achieving better enantioresolution and higher separation efficiencies for each compound. To fully resolve the mixture of six enantiomers, parameters such as buffer pH and concentration sample injection have been then investigated. A mixture of ACN/water (90:10, v/v) containing 5 mM ammonium borate buffer pH 9.0 enabled the complete separation of the three couples of enantiomers in less than 30 min. The optimized CEC method was therefore validated and applied to the analysis of pharmaceutical formulation declared to contain only AML racemate. PMID:23775281
Phase Transition in Unrestricted Random SAT
Schuh, Bernd R
2012-01-01
For random CNF formulae with m clauses, n variables and an unrestricted number of literals per clause the transition from high to low satisfiability can be determined exactly for large n. The critical density m/n turns out to be strongly n-dependent, ccr = ln(2)/(1-p)^^n, where pn is the mean number of positive literals per clause.This is in contrast to restricted random SAT problems (random K-SAT), where the critical ratio m/n is a constant. All transition lines are calculated by the second moment method applied to the number of solutions N of a formula. In contrast to random K-SAT, the method does not fail for the unrestricted model, because long range interactions between solutions are not cut off by disorder.
Wang Dao-Cai; Luo Jia; Yao Shun; Song Hang
2016-01-01
In the light of the chiral resolution mechanism and structures of brush-type CSP, a new chiral selector 4′-carboxyl-1′-ursolic methyl ester-3β-yl-benzoate has been prepared. Then the terpenoid chiral selector was covalently linked to 3-aminopropyl silica gel. Its structure identification data are provided by 1H NMR, MS and elementary analysis. The enantiodiscriminating capability of the brush-type CSP was evaluated by static adsorption experiment with methyl mandelate, aniline derivative of m...
Phase transition in extended thermodynamic phase space and charged Horava-Lifshitz black holes
Poshteh, Mohammad Bagher Jahani
2016-01-01
For charged black holes in Horava-Lifshitz gravity, it is shown that a second order phase transition takes place in extended phase space. We study the behavior of specific heat and free energy at the point of transition in canonical and grand canonical ensembles and show that the black hole falls into a state which is locally and globally stable. We relate the second order nature of phase transition to the fact that the phase transition occurs at a sharp temperature and not over a temperature interval. By taking cosmological constant as thermodynamic pressure for charged black holes, we extend Ehrenfest's equations. We obtain nine equations and show that, all of them are satisfied at the point in which the specific heat diverges. We also apply geometrothermodynamics to extended phase space and show that the scalar curvature of Quevedo metric diverges at the point at which the second order phase transition takes place.
A Quantum Phase Transition in the Cosmic Ray Energy Distribution
Widom, A; Srivastava, Y
2015-01-01
We here argue that the "knee" of the cosmic ray energy distribution at $E_c \\sim 1$ PeV represents a second order phase transition of cosmic proportions. The discontinuity of the heat capacity per cosmic ray particle is given by $\\Delta c=0.450196\\ k_B$. However the idea of a deeper critical point singularity cannot be ruled out by present accuracy in neither theory nor experiment. The quantum phase transition consists of cosmic rays dominated by bosons for the low temperature phase E E_c$. The low temperature phase arises from those nuclei described by the usual and conventional collective boson models of nuclear physics. The high temperature phase is dominated by protons. The transition energy $E_c$ may be estimated in terms of the photo-disintegration of nuclei.
Yang, Xiaoyu; Phipps, Robert J; Toste, F Dean
2014-04-01
We report a study involving the successful merger of two separate chiral catalytic cycles: a chiral anion phase-transfer catalysis cycle to activate Selectfluor and an enamine activation cycle, using a protected amino acid as organocatalyst. We have demonstrated the viability of this approach with the direct asymmetric fluorination of α-substituted cyclohexanones to generate quaternary fluorine-containing stereocenters. With these two chiral catalytic cycles operating together in a matched sense, high enantioselectivites can be achieved, and we envisage that this dual catalysis method has the potential to be more broadly applicable, given the breadth of enamine catalysis. It also represents a rare example of chiral enamine catalysis operating successfully on α-branched ketones, substrates commonly inert to this activation mode.
Phase Transitions in Antibody Solutions: from Pharmaceuticals to Human Disease
Wang, Ying; Lomakin, Aleksey; Benedek, George; Dana Farber Cancer Institute Collaboration; Amgen Inc. Collaboration
2014-03-01
Antibodies are very important proteins. Natural antibodies play essential role in the immune system of human body. Pharmaceutical antibodies are used as drugs. Antibodies are also indispensable tools in biomedical research and diagnostics. Recently, a number of observations of phase transitions of pharmaceutical antibodies have been reported. These phase transitions are undesirable from the perspective of colloid stability of drug solutions in processing and storage, but can be used for protein purification, X-ray crystallography, and improving pharmokinetics of drugs. Phase transitions of antibodies can also take place in human body, particularly in multiple myeloma patients who overproduce monoclonal antibodies. These antibodies, in some cases, crystallize at body temperature and cause severe complications called cryoglobulinemia. I will present the results of our current studies on phase transitions of both pharmaceutical antibodies and cryoglobulinemia-associated antibodies. These studies have shown that different antibodies have different propensity to undergo phase transitions, but their phase behavior has universal features which are remarkably different from those of spherical proteins. I will discuss how studies of phase behavior can be useful in assessing colloid stability of pharmaceutical antibodies and in early diagnostics of cryoglobulinemia, as well as general implications of the fact that some antibodies can precipitate at physiological conditions.
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.
Effects of phase transition induced density fluctuations on pulsar dynamics
Energy Technology Data Exchange (ETDEWEB)
Bagchi, Partha, E-mail: partha@iopb.res.in [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Das, Arpan, E-mail: arpan@iopb.res.in [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Layek, Biswanath, E-mail: layek@pilani.bits-pilani.ac.in [Department of Physics, Birla Institute of Technology and Science, Pilani - 333031 (India); Srivastava, Ajit M., E-mail: ajit@iopb.res.in [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India)
2015-07-30
We show that density fluctuations during phase transitions in pulsar cores may have non-trivial effects on pulsar timings, and may also possibly account for glitches and anti-glitches. These density fluctuations invariably lead to non-zero off-diagonal components of the moment of inertia, leading to transient wobbling of star. Thus, accurate measurements of pulsar timing and intensity modulations (from wobbling) may be used to identify the specific pattern of density fluctuations, hence the particular phase transition, occurring inside the pulsar core. Changes in quadrupole moment from rapidly evolving density fluctuations during the transition, with very short time scales, may provide a new source for gravitational waves.
Classicality of the order parameter during a phase transition
Lombardo, F C; Monteoliva, D; Lombardo, Fernando C.; Mazzitelli, Francisco D.; Monteoliva, Diana
2000-01-01
We analize the quantum to classical transition of the order parameter insecond order phase transitions. We consider several toy models in nonrelativistic quantum mechanics. We study the dynamical evolution of a wavepacket initially peaked around a local maximum of the potential usingvariational approximations and also exact numerical results. The influence ofthe environment on the evolution of the density matrix and the Wigner functionis analized in great detail. We also discuss the relevance of our results tothe analysis of phase transitions in field theory. In particular, we argue thatprevious results about classicality of the order parameter in O(N) models maybe consequences of the large $N$ approximation.
Gravitational waves from cosmological first order phase transitions
Hindmarsh, Mark; Rummukainen, Kari; Weir, David
2015-01-01
First order phase transitions in the early Universe generate gravitational waves, which may be observable in future space-based gravitational wave observatiories, e.g. the European eLISA satellite constellation. The gravitational waves provide an unprecedented direct view of the Universe at the time of their creation. We study the generation of the gravitational waves during a first order phase transition using large-scale simulations of a model consisting of relativistic fluid and an order parameter field. We observe that the dominant source of gravitational waves is the sound generated by the transition, resulting in considerably stronger radiation than earlier calculations have indicated.
Exotic phase transitions of k-cores in clustered networks
Bhat, Uttam; Hébert-Dufresne, Laurent
2016-01-01
The giant $k$-core --- maximal connected subgraph of a network where each node has at least $k$ neighbors --- is important in the study of phase transitions and in applications of network theory. Unlike Erd\\H{o}s-R\\'enyi graphs and other random networks where $k$-cores emerge discontinuously for $k\\ge 3$, we show that transitive linking (or triadic closure) leads to 3-cores emerging through single or double phase transitions of both discontinuous and continuous nature. We also develop a $k$-core calculation that includes clustering and provides insights into how high-level connectivity emerges.
Gritti, Fabrice; Guiochon, Georges
2014-01-31
The mechanism of mass transfer was studied on a cellulose-based chiral stationary phase (CSP, Lux Cellulose-1) using aqueous mixtures of acetonitrile (50/50-90/10, v/v) or methanol (90/10 and 100/0, v/v) as the mobile phase. An experimental protocol validated in RPLC and HILIC chromatography and recently extended to chiral RPLC was applied. The five mass-transfer contributions (longitudinal diffusion, short-range and long-range eddy dispersion, solid-liquid mass transfer resistances due to finite intra-particle diffusivity and slow adsorption-desorption) to the reduced height equivalent to a theoretical plate (HETP) were measured. The experimental results show that the adsorption rate constants kads of trans-stilbene enantiomers onto the CSP are three times larger with acetonitrile than with methanol as the organic modifier. This is correlated to the decrease of enantioselectivity from 1.4 (in methanol) to only 1.1 (in acetonitrile). The amount of solvent needed to achieve a separation factor of exactly 2.0 was determined. This showed that analysis cost could be reduced seven times by selecting pure methanol as the eluent for a 5cm long column rather than an acetonitrile-water mixture for a longer (20-45cm) column.
Transition to Phase Synchronization Through Generalized Synchronization
Institute of Scientific and Technical Information of China (English)
高建; 郑志刚; 何岱海; 张廷宪
2003-01-01
Synchronization in drive-response chaotic systems is studied. For a small mismatch of the natural frequency of the drive and response oscillators, phase synchronization comes before generalized synchronization. For moderate and even large parameter misfits, generalized synchronization can be achieved before phase synchronization. The mechanism of these two different bifurcations is interpreted in terms of the local-minimal-fluctuation method.It is found that the qualitative changes of local-minimal-fluctuations of the response system well manifests the appearance of generalized synchronization.