Cooling of strange stars in the color-flavor locked phase with a rotating crust Cooling of strange stars in the color-flavor locked phase with a rotating crust

The presence of the color-flavor locked (CFL) phase strongly suppresses the neutrino emission processes and the quark specific heat. As a result the cooling of the strange stars in the CFL phase is dominated by deconfinement heating and surface emission. The temperature of these stars with strong magnetic field ($B{\geq}10^{10}G$) rise significantly during the first several ten or hundred years, which may be an effective signature of strange stars as implicated by pulsar 0540-69. Furthermore a limit line is predicted, which means compact stars have an upper limit temperature at any moment. We still may search for the candidates for strange stars in the CFL phase along the limit line. The presence of the color-flavor locked (CFL) phase strongly suppresses the neutrino emission processes and the quark specific heat. As a result the cooling of the strange stars in the CFL phase is dominated by deconfinement heating and surface emission. The temperature of these stars with strong magnetic field ($B{\geq}10^{10}G$) rise significantly during the first several ten or hundred years, which may be an effective signature of strange stars as implicated by pulsar 0540-69. Furthermore a limit line is predicted, which means compact stars have an upper limit temperature at any moment. We still may search for the candidates for strange stars in the CFL phase along the limit line.Comment: 9 pages, 3 figures 9 pages, 3 figure

Charge-spin mutual entanglement: A case study by exact diagonalization of the one hole doped tt-JJ loop

A doped Mott insulator exhibits peculiar properties associated with its singular sign structure. As a case study, we investigate the ground state and excitations of finite-size Heisenberg loops doped with one hole by exact diagonalization. We find that there appear a series of quantum critical points (QCPs), which separate regimes by distinct total momenta along the axis of the ratio $J/t$ ($J$ and $t$ denote the superexchange coupling and hopping integral, respectively). Each QCP involves a crystal momentum jump with level crossing or merging of lowest energy levels. In contrast to the conserved total momentum, however, a broad momentum distribution of \emph{individual} electrons is also found, indicating charge incoherence/translational symmetry breaking in violation of the one-to-one correspondence. Such a charge incoherence is further related to quantum fluctuations or the transverse part of ${\bf S}^2=3/4$ with $S^z=\pm 1/2$ in the one-hole ground state. Turning off the phase-string sign structure, by contrast, we show that the total momentum of the ground state reduces to null in the whole regime of $J/t$ with no more QCP or incoherence. We introduce the so-called charge-spin mutual entanglement to characterize these novel properties, with the entanglement spectrum providing additional information on the charge incoherence, which capture the nature of strong correlation due to the many-body quantum interference.Comment: 11 pages, 10 figure

Two-hole ground state wavefunction: Non-BCS pairing in a tt-JJ two-leg ladder system

Superconductivity is usually described in the framework of the Bardeen-Cooper-Schrieffer (BCS) wavefunction, which even includes the resonating-valence-bond (RVB) wavefunction proposed for the high-temperature superconductivity in the cuprate. A natural question is \emph{if} any fundamental physics could be possibly missed by applying such a scheme to strongly correlated systems. Here we study the pairing wavefunction of two holes injected into a Mott insulator/antiferromagnet in a two-leg ladder using variational Monte Carlo (VMC) approach. By comparing with density matrix renormalization group (DMRG) calculation, we show that a conventional BCS or RVB pairing of the doped holes makes qualitatively wrong predictions and is incompatible with the fundamental pairing force in the $t$-$J$ model, which is kinetic-energy-driven by nature. By contrast, a non-BCS-like wavefunction incorporating such novel effect will result in a substantially enhanced pairing strength and improved ground state energy as compared to the DMRG results. We argue that the non-BCS form of such a new ground state wavefunction is essential to describe a doped Mott antiferromagnet at finite doping.Comment: 11 pages, 5 figure

Hidden spin current in doped Mott antiferromagnets

We investigate the nature of doped Mott insulators using exact diagonalization and density matrix renormalization group methods. Persistent spin currents are revealed in the ground state, which are concomitant with a nonzero total momentum or angular momentum associated with the doped hole. The latter determines a nontrivial ground state degeneracy. By further making superpositions of the degenerate ground states with zero or unidirectional spin currents, we show that different patterns of spatial charge and spin modulations will emerge. Such anomaly persists for the odd numbers of holes, but the spin current, ground state degeneracy, and charge/spin modulations completely disappear for even numbers of holes, with the two-hole ground state exhibiting a d-wave symmetry. An understanding of the spin current due to a many-body Berry-like phase and its impact on the momentum distribution of the doped holes will be discussed.Comment: 9 pages, 9 figures, update second version including more data and discussion adde

Oblique Corrections in the MSSM at One Loop. I. Scalars

This paper is devoted to reconsider the one-loop oblique corrections arising from the scalar superpartners in the MSSM, i.e, the squarks, the sleptons and the scalars in Higgs sector. We explicitly present the complete one-loop forms of self-energy corrections to the gauge bosons of SM electroweak gauge groups, as well as their descendants the $S$, $T$ and $U$ parameters, which can be directly applied to constrain the parameter space of the MSSM. Our results about one-loop self energies are found to agree with Drees, Hagiwara, and Yamada (1992), Pierce et al. (1997). Nevertheless, the $S$, $T$ and $U$ parameters aren't in agreement with Dobado, Herrero and Penaranda (1999).Comment: short version to appear in Advances in High Energy Physic