scholarly journals QUARK SPECTRUM ABOVE THE CRITICAL TEMPERATURE FROM SCHWINGER–DYSON EQUATION

2007 ◽  
Vol 16 (07n08) ◽  
pp. 2282-2288
Author(s):  
MASAYASU HARADA ◽  
YUKIO NEMOTO ◽  
SHUNJI YOSHIMOTO
Keyword(s):  
Critical Temperature ◽  
Weak Coupling ◽  
Gauge Coupling ◽  
Dyson Equation ◽  
Coupling Region ◽  
Chiral Phase ◽  
Loop Approximation ◽  
Wide Range ◽  
Region Temperature ◽  
Two Peaks

We investigate a spectrum of a fermion, which we call a quark, above the critical temperature of the chiral phase transition in a gauge theory using the Schwinger–Dyson (SD) equation. The SD equation enables us to study the spectrum over a wide range of the gauge coupling. It is shown that the quark spectrum has two sharp peaks which correspond to the normal quasi-quark and the plasmino and is consistent with that obtained in the hard thermal loop approximation in the weak coupling region, while it has also two peaks but with smaller thermal masses and broader widths in the strong coupling region. Temperature-dependence of the quark spectrum is also discussed.

scholarly journals Importance of $${{d}}_{{{xy}}}$$ orbital and electron correlation in iron-based superconductors revealed by phase diagram for 1111-system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tsuyoshi Kawashima ◽  
Shigeki Miyasaka ◽  
Hirokazu Tsuji ◽  
Takahiro Yamamoto ◽  
Masahiro Uekubo ◽  
...  
Keyword(s):  
Electron Correlation ◽  
Weak Coupling ◽  
Structural Parameters ◽  
Structural Flexibility ◽  
Superconducting Transition ◽  
Iron Based Superconductors ◽  
Wide Range ◽  
Band Filling ◽  
Iron Based ◽  
Correlation Strength

AbstractThe structural flexibility at three substitution sites in LaFeAsO enabled investigation of the relation between superconductivity and structural parameters over a wide range of crystal compositions. Substitutions of Nd for La, Sb or P for As, and F or H for O were performed. All these substitutions modify the local structural parameters, while the F/H-substitution also changes band filling. It was found that the superconducting transition temperature $$T_{\text{c}}$$ T c is strongly affected by the pnictogen height $$h_{Pn}$$ h Pn from the Fe-plane that controls the electron correlation strength and the size of the $$d_{xy}$$ d xy hole Fermi surface (FS). With increasing $$h_{Pn}$$ h Pn , weak coupling BCS superconductivity switches to the strong coupling non-BCS one where electron correlations and the $$d_{xy}$$ d xy hole FS may be important.

Path Integral Calculations of Particle Self-Energy and Effective Mass in Coulomb Systems

1997 ◽  
Vol 11 (04) ◽  
pp. 129-138 ◽  
Author(s):  
V. Sa-Yakanit ◽  
V. D. Lakhno ◽  
Klaus Haß
Keyword(s):  
Effective Mass ◽  
Path Integral ◽  
State Energy ◽  
Coulomb Systems ◽  
Integral Approach ◽  
Coupling Region ◽  
Self Energy ◽  
Consistent Approximation ◽  
A Value ◽  
Wide Range

The generalized path integral approach is applied to calculate the ground state energy and the effective mass of an electron-plasmon interacting system for a wide range of densities. It is shown that in the self-consistent approximation an abrupt transition between the weak coupling and the strong coupling region of interaction exists. The transition occurs at low electron densities according to a value of 418 for rs, when Wigner crystallization is possible. For densities of real metals, the electron bandwidth is calculated and a comparison with experimental results is given.

scholarly journals Searching for Z′ bosons at the P2 experiment

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
P. S. Bhupal Dev ◽  
Werner Rodejohann ◽  
Xun-Jie Xu ◽  
Yongchao Zhang
Keyword(s):  
Parity Violation ◽  
Z Bosons ◽  
Gauge Coupling ◽  
New Physics ◽  
Polarized Electrons ◽  
Mixing Angles ◽  
Charge Assignment ◽  
Wide Range ◽  
Discovery Potential ◽  
Left And Right

Abstract The P2 experiment aims at high-precision measurements of the parity-violating asymmetry in elastic electron-proton and electron-12C scatterings with longitudinally polarized electrons. We discuss here the sensitivity of P2 to new physics mediated by an additional neutral gauge boson Z′ of a new U(1)′ gauge symmetry. If the charge assignment of the U(1)′ is chiral, i.e., left- and right-handed fermions have different charges under U(1)′, additional parity-violation is induced directly. On the other hand, if the U(1)′ has a non-chiral charge assignment, additional parity-violation can be induced via mass or kinetic Z-Z′ mixing. By comparing the P2 sensitivity to existing constraints, we show that in both cases P2 has discovery potential over a wide range of Z′ mass. In particular, for chiral models, the P2 experiment can probe gauge couplings at the order of 10−5 when the Z′ boson is light, and heavy Z′ bosons up to 79 (90) TeV in the proton (12C) mode. For non-chiral models with mass mixing, the P2 experiment is sensitive to mass mixing angles smaller than roughly 10−4, depending on model details and gauge coupling magnitude.

Simplified coupling power model for fibers fusion

2009 ◽  
Vol 17 (3) ◽  
Author(s):  
J. Saktioto ◽  
J. Ali ◽  
M. Fadhali
Keyword(s):  
Refractive Index ◽  
Propagation Constant ◽  
Tunable Filter ◽  
Experimental Result ◽  
Total Power ◽  
Optical Parameters ◽  
Coupling Region ◽  
Ratio Distribution ◽  
Hydrogen Flow ◽  
Wide Range

AbstractFiber coupler fabrication used for an optical waveguide requires lossless power for an optimal application. The previous research coupled fibers were successfully fabricated by injecting hydrogen flow at 1 bar and fused slightly by unstable torch flame in the range of 800–1350°C. Optical parameters may vary significantly over wide range physical properties. Coupling coefficient and refractive index are estimated from the experimental result of the coupling ratio distribution from 1% to 75%. The change of geometrical fiber affects the normalized frequency V even for single mode fibers. V is derived and some parametric variations are performed on the left and right hand side of the coupling region. A partial power is modelled and derived using V, normalized lateral phase constant u, and normalized lateral attenuation constant, w through the second kind of modified Bessel function of the l order, which obeys the normal mode and normalized propagation constant b. Total power is maintained constant in order to comply with the energy conservation law. The power is integrated through V, u, and w over the pulling length of 7500 µm for 1-D. The core radius of a fiber significantly affects V and power partially at coupling region rather than wavelength and refractive index of core and cladding. This model has power phenomena in transmission and reflection for an optical switch and tunable filter.

A possible massive solution to the Dyson equation with small gauge coupling

1993 ◽  
Vol 302 (4) ◽  
pp. 442-446 ◽  
Author(s):  
Giuliano Preparata ◽  
She-Sheng Xue
Keyword(s):  
Gauge Coupling ◽  
Dyson Equation ◽  
Small Gauge ◽  
Massive Solution

scholarly journals Ratio of Quark Masses in Duality Theories

2003 ◽  
Vol 18 (25) ◽  
pp. 1743-1752
Author(s):  
G. Cleaver ◽  
K. Tanaka
Keyword(s):  
Strong Coupling ◽  
Duality Theory ◽  
Weak Coupling ◽  
Singular Points ◽  
Bare Mass ◽  
Coupling Region ◽  
Quark Masses ◽  
Mass Ratios ◽  
Quark Flavors

We consider N=2 SU(2) Seiberg–Witten duality theory for models with N f =2 and N f =3 quark flavors. We investigate arbitrary large bare mass ratios between two or three quarks at the singular points. For N f =2 we explore large bare mass ratios corresponding to a singularity in the strong coupling region. For N f =3 we determine the location of both strong and weak coupling singularities that produce specific large bare mass ratios.

scholarly journals Thermal conductivity of the quark matter for the SU(2) light-flavor sector

2015 ◽  
Vol 30 (10) ◽  
pp. 1550054 ◽  
Author(s):  
Seung-il Nam
Keyword(s):  
Thermal Conductivity ◽  
Quark Matter ◽  
Quark Mass ◽  
Chemical Potential ◽  
Entropy Density ◽  
Model Parameters ◽  
Chiral Phase ◽  
Nuclear Matter Density ◽  
Wide Range ◽  
Monotonically Decreasing Function

We investigate the thermal conductivity (κ) of the quark matter at finite quark chemical potential (μ) and temperature (T), employing the Green–Kubo formula, for the SU(2) light-flavor sector with the finite current-quark mass m = 5 MeV . As a theoretical framework, we construct an effective thermodynamic potential from the (μ, T)-modified liquid-instanton model (mLIM). Note that all the relevant model parameters are designated as functions of T, using the trivial-holonomy caloron solution. By solving the self-consistent equation of mLIM, we acquire the constituent-quark mass M0 as a function of T and μ, satisfying the universal-class patterns of the chiral phase transition. From the numerical results for κ, we observe that there emerges a peak at μ≈200 MeV for the low-T region, i.e. T≲100 MeV . As T increase over T≈100 MeV , the curve for κ is almost saturated as a function of T in the order of ~ 10-1 GeV 2, and grows with respect to μ smoothly. At the normal nuclear-matter density ρ0 = 0.17 fm -3, κ shows its maximum 6.22 GeV 2 at T≈10 MeV , then decreases exponentially down to κ≈0.2 GeV 2. We also compute the ratio of κ and the entropy density, i.e. κ/s as a function of (μ, T) which is a monotonically decreasing function for a wide range of T, then approaches a lower bound at very high T: κ/s min ≳0.3 GeV -1 in the vicinity of μ = 0.

scholarly journals LANDAU GHOSTS AND ANTI-GHOSTS IN CONDENSED MATTER AND HIGH DENSITY HADRONIC MATTER

2002 ◽  
Vol 16 (30) ◽  
pp. 1201-1209 ◽  
Author(s):  
S. SIVASUBRAMANIAN ◽  
A. WIDOM ◽  
Y. N. SRIVASTAVA
Keyword(s):  
Room Temperature ◽  
Condensed Matter ◽  
Dyson Equation ◽  
Hadronic Matter ◽  
Asymptotic Freedom ◽  
Polar Liquids ◽  
Quantum Chromo Dynamics ◽  
Color Confinement ◽  
Loop Approximation ◽  
Lorentz Equation

It is observed that the "ghost" (originally discovered by Landau in quantum electro-dynamics) and its counterparts in other theories are indeed ubiquitous as they occur in a one-loop approximation to any conventional (unbroken) gauge theory. The mechanism is first exposed in its generality via the Dyson equation and a simple but explicit example in condensed matter is provided through the static Clausius–Mossotti equation and its dynamic counterpart, the Lorenz–Lorentz equation. The physical phase transition phenomenon associated with it is found to be super-radiance. We verify quantitatively that water (and many other polar liquids) are indeed super-radiant at room temperature. In quantum chromo-dynamics on the other hand, we encounter, thanks to asymptotic freedom, an "anti-ghost" which is closely associated with color confinement. Thus, in QCD, free quarks and glue exist in a super-radiant phase and hadronic matter exists in the normal one.

EFFECTIVE THEORY OF BOSONIC SUPERFLUIDS

1994 ◽  
Vol 08 (15) ◽  
pp. 2021-2039 ◽  
Author(s):  
ADRIAAN M.J. SCHAKEL
Keyword(s):  
Critical Temperature ◽  
Weak Coupling ◽  
Particle Number ◽  
Landau Theory ◽  
Effective Theory ◽  
Bcs Theory ◽  
Goldstone Mode ◽  
Zero Temperature ◽  
Temperature Expansion ◽  
High Temperature Expansion

We discuss the effective theory of a bosonic superfluid whose microscopic behavior is described by a nonrelativistic, weak-coupling Φ4 theory in the phase with broken particle number symmetry, both at zero temperature and in the vicinity of the phase transition. In the zero-temperature regime, the theory is governed by the gapless Goldstone mode resulting from the broken .symmetry. Although this mode is gapless, the effective theory turns out to be Gallilei invariant. The regime just below the critical temperature is approached in a high-temperature expansion which is shown to be consistent with the weak-coupling assumption of the theory. We calculate the critical temperature, the co-efficients of the Landau theory, and the finite-temperature sound velocity. A comparison with BCS theory is given.

Argon and nitrogen adsorption on graphite at high temperatures

1991 ◽  
Vol 56 (3) ◽  
pp. 569-579
Author(s):  
Eduardo Jorge Bottani ◽  
Jorge Luis Llanos ◽  
Lydia Ethel Cascarini de Torre
Keyword(s):  
Critical Temperature ◽  
Adsorption Isotherm ◽  
High Temperatures ◽  
Nitrogen Adsorption ◽  
Two Dimensional ◽  
Adsorbed Film ◽  
Adsorbed Phase ◽  
Wide Range ◽  
Argon Adsorption ◽  
The Hill

Nitrogen and argon adsorption on two graphites differing in their surface homogeneity was studied in a wide range of temperatures (77.5 K up to 183.2 K). The experimentally determined entropy of the adsorbed phase and isoteric heat of adsorption were analyzed. The Hill-de Boer adsorption isotherm was employed to calculate the apparent two-dimensional critical temperature. The behaviour of the adsorbed film was analyzed to explain the influence exerted upon it by temperature and surface homogenity.

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