Narrow Results

We construct the chiral perturbation theory for two-color QCD with two quark flavors as an effective theory on the SO(6)/SO(5) coset space. This formulation turns out to be particularly useful for extracting the physical content of the theory when finite baryon and isospin chemical potentials are introduced, and Bose–Einstein condensation sets on.

Doubly differential transverse momentum spectra of strange mesons $K^{\ast }{(892)}^0$ and $K^{\ast }{(892)}^{\pm }$ within rapidity interval of $|y|<0.5$ are studied by using Monte Carlo event generators in pp, pPb and PbPb collisions at different center-of-mass energies. The predictions of simulations are compared to the ALICE data. The fitting of doubly differential transverse momentum spectra of ALICE data is performed by using Tsallis distribution function. To check the quality of the fitting, chemical potential is also set to zero value. The extracted values of the non-extensive parameter ($q$), a chemical potential $\mu$ and effective Tsallis temperature $T$ for different particle species have been obtained from the thermodynamically consistent Tsallis distribution function. It is observed that the effective Tsallis temperature increases at different center-of-mass energies. The predictions of the MC event generators, i.e. PYTHIA8 CR and HIJING 2.0 are compared to the ALICE data, deviations are observed which may be due to the reshuffling of parton colors and string fragmentation.

Formation of topological objects during phase transitions has been discussed extensively in literature. In all these discussions, defects and antidefects form with equal probabilities. In contrast, many physical situations, such as formation of baryons in relativistic heavy-ion collisions at present energies, flux tube formation in superconductors in the presence of external magnetic field, and formation of superfluid vortices in a rotating vessel, require a mechanism which can bias (say) defects over antidefects. Such a bias can crucially affect defect–antidefect correlations, apart from its effects on defect density. In this paper we initiate an investigation for the basic mechanism of biased formation of defects. For Skyrmions in 1+1 dimensions, we show that incorporation of a chemical potential term in the effective potential leads to a domain structure where order parameter is spatially varying. We show that this leads to biased formation of Skyrmions.

Model of superconductivity in the metallic phase of strongly correlated electrons in a half-filled narrow band forming a paramagnetic spin liquid is presented. A qualitatively new ground state and other eigenstates for the superconducting phase are found. Thermodynamic functions are derived within the Bogolubov method. Analytical formulae for the free energy as well as the gap equation and the equation for the chemical potential are presented. It is shown that the energy gap and the chemical potential are mutually correlated functions which must be simultaneously derived in a self-consistent manner. The gap equation and the equation for the chemical potential are numerically solved. The energy gap is doubly-valued in the subcritical temperature region, however only for the higher values of the gap the superconducting phase is stable. The phase transition between the superconducting and the normal phase is found to be of the first order with a conspicuous discontinuity in the entropy. Moreover it is shown that the derivation of the superconducting specific heat from the thermodynamic potential difference requires to include a chemical potential contribution.

The advanced methodology of Green's function method and application of this new methodology have resulted in a set of interesting conclusions concerning thin film properties. It has been concluded that thin films possess high superconductive, thermoisolation and acoustical isolation properties. It is also concluded that physical characteristics of thin films are spatially dependent and that this spatial dependence can be the basis for widening of the nanostructures application field.

We investigate the thermodynamic properties of a trapped Bose gas of Rb atoms interacting through a repulsive potential at low but finite temperature (k_BT < μ < T_c) by Quantum Monte Carlo method based upon the generalization of Feynman-Kac method^1-3 applicable to many-body systems at T=0 to finite temperatures. In this paper, we report temperature variation of condensation fraction, chemical potential, density profile, total energy of the system, release energy, frequency shifts and moment of inertia within the realistic potential model (Morse type) for the first time by diffusion Monte Carlo technique. The most remarkable success was in achieving the same trend in the temperature variation of frequency shifts as was observed in JILA⁴ for both m=2 and m=0 modes. For other things, we agree with the work of Giorgini et al.,⁵ Pitaevskii et al.⁶ and Krauth.⁷

We examine the doping dependence of SC gap (Δ) and chemical potential (μ) of the hole-doped cuprates by using the Fulde model. It is assumed that SC arises due to BCS pairing mechanism in lattices of Cu–O planes. The expression for SC, AFM, and doping concentration are calculated analytically by using the Green function technique of D. N. Zubarev. The value of SC gap (Δ) and chemical potential (μ) are solved self-consistently for different model parameters. The variation of critical temperature and chemical potential with doping are also studied.

We study the density of states of zigzag carbon nanotube (CNT) doped with both Boron and nitrogen atoms as donor and acceptor impurities, respectively. The effect of scattering of the electrons on the electronic spectrum of the system can be obtained via adding random on-site energy term to the tight binding model Hamiltonian which describes the clean system. Green's function approach has been implemented to find the behavior of electronic density. Due to Boron (Nitrogen) doping, Fermi surface tends to the valence (conduction) band of semiconductor CNT so that the energy gap width reduces. Furthermore the density of states of disordered metallic zigzag CNTs includes a peak near the Fermi energy.

We study physical properties of the symmetric diamond chain with delocalized interstitial spins. We derive an exact solution of the model and characterize the phases of the system at zero temperature. On the basis of this solution, we examine its magnetic and thermal properties as well. The case of nonconserved electron number is then considered. There are phases, which we term as nonclassical, for which electrons in Hubbard dimers are in quantum entangled states. We finally study quantum entanglement depending on Hamiltonian parameters and temperature.

Thermodynamic relations like the Gibbs–Duhem are valid from the lowest to the highest temperatures. But they cannot by themselves provide any specific temperature behavior of thermodynamic functions like the chemical potential. In this work, we show that if some general conditions are attached to the Gibbs–Duhem equation, it is possible to obtain the low temperature form of the chemical potential for the ideal Fermi and Bose gases very directly.

An analysis is made of the low-temperature behavior of the chemical potential $\mu$ of a quasi-two-dimensional electron gas near the resonance point (at the bottom of the miniband) and far from it. Low-temperature analytical formulas for $\mu (T)$ are obtained under the conditions of the existence of an arbitrary number of minibands. It is shown that with the increasing temperature near the resonance point, the chemical potential decreases linearly and exponentially slowly in the middle of the resonance points. Analytical formulas are compared to the numerical solutions.

This paper refers to another attempt to search for spherical double shell closure nuclei beyond Z = 82, N = 126. All calculations and results are based on a newly developed approach entitled as simple effective interaction (SEI). Our results predict that the combination of magic nucleus occurs at N = 182 (Z = 114, 120, 126). All possible evidences for the occurrence of magic nuclei are discussed systematically. And, the obtained results for all observables are compared with the relativistic mean field theory for NL3 parameter.

We study the vorticity patterns in relativistic heavy ion collisions with respect to the collision energy. The collision energy is related to the chemical potential used in the thermal — statistical models that assume approximate chemical equilibrium after the relativistic collision. We use the multiphase transport model (AMPT) to study the vorticity in the initial parton phase as well as the final hadronic phase of the relativistic heavy ion collision. We find that as the chemical potential increases, the vortices are larger in size. Using different definitions of vorticity, we find that vorticity plays a greater role at lower collision energies than at higher collision energies. We also look at other effects of the flow patterns related to the shear viscosity at different collision energies. We find that the shear viscosity obtained is almost a constant with a small decrease at higher collision energies. We also look at the elliptic flow as it is related to viscous effects in the final stages after the collision. Our results indicate that the viscosity plays a greater role at higher chemical potential and lower collision energies.

In this study, we investigate the ordered morphologies on the binary blend of diblock copolymers film induced by the mobile wettable nanoparticles on the substrate. The film forms highly ordered microphase and macrophase morphologies. We constructed the phase diagram, which suggests that the ordered-striped macrophase structures are due to the competition equilibrium of the wetting strength and the chemical potential amplitude upon the nanoparticles. The morphologies of the binary blend film form the striped pattern of different periods with the changing oscillation period of the chemical potential. The short-range interaction between monomers only alters the microphase structures. We analyzed the variation in the interfacial energy, the wetting energy and the particles/substrate’s coupling energy on different morphologies. The results provide a new control mechanism to stabilize the ordered microphase and macrophase structures within the copolymer blend film.

A numerical calculation of the temperature dependence of the chemical potential and for various values of the filling factor $\nu$ of the Landau level is carried out. The degree of filling of each Landau level is found as a function of temperature. Analytical calculations were carried out in the model of an ideal Fermi gas both without taking into account the broadening of the Landau levels $\mathrm{\Gamma }=0$ and taking into account their broadening $\mathrm{\Gamma }>0$. An analytical formula is found that describes the dependences of $\mu (T,\nu )$ at $\mathrm{\Gamma }=0$ and low temperatures. A low-temperature formula for the dependence of $\mu (T∕\mathrm{\Gamma },{\epsilon }_F)$ based on the Sommerfeld expansion is also given. The influence of the intra- and interlevel thermal excitations on changes in the chemical potential with temperature is discussed.

It is widely assumed that the observed Universe is accelerating due to the existence of a new fluid component called dark energy. In this article, the thermodynamics consequences of a nonzero chemical potential on the dark energy component is discussed with special emphasis to the phantom fluid case. It is found that if the dark energy fluid is endowed with a negative chemical potential, the phantom field hypothesis becomes thermodynamically consistent with no need of negative temperatures as recently assumed in the literature.