119180124
Some recent progress on quark pairings in dense quark and nuclear matter
In this review article we give a brief overview on some recent progress in quark pairings in dense quark/nuclear matter mostly developed in the past five years. We focus on following aspects in particular: the BCS-BEC crossover in the CSC phase, the baryon formation and dissociation in dense quark/nuclear matter, the Ginzburg-Landau theory for three-flavor dense matter with UA(1) anomaly, and the collective and Nambu-Goldstone modes for the spin-one CSC.
118613298
Baryon formation and dissociation in dense hadronic and quark matter
Abstract We study the formation of baryons as composed of quarks and diquarks in hot and dense hadronic matter in a Nambu–Jona-Lasinio (NJL)-type model. We first solve the Dyson–Schwinger equation for the diquark propagator and then use this to solve the Dyson–Schwinger equation for the baryon propagator. We find that stable baryon resonances exist only in the phase of broken chiral symmetry. In the chirally symmetric phase, we do not find a pole in the baryon propagator. In the color-superconducting phase, there is a pole, but it has a large decay width. The diquark does not need to be stable in order to form a stable baryon, a feature typical for so-called Borromean states. Varying the strength of the diquark coupling constant, we also find similarities to the properties of an Efimov state.
119215988
Magnetic tuning of the relativistic BCS-BEC crossover
The effect of an applied magnetic field in the crossover from Bose-Einstein condensate (BEC) to Bardeen-Cooper-Schrieffer (BCS) pairing regimes is investigated. We use a model of relativistic fermions and bosons inspired by those previously used in the context of cold fermionic atoms and in the magnetic-color-flavor-locking phase of color superconductivity. It turns out that as with cold atom systems, an applied magnetic field can also tune the BCS-BEC crossover in the relativistic case. We find that no matter what the initial state is at B=0, for large enough magnetic fields the system always settles into a pure BCS regime. In contrast to the atomic case, the magnetic field tuning of the crossover in the relativistic system is not connected to a Feshbach resonance, but to the relative numbers of Landau levels with either BEC or BCS type of dispersion relations that are occupied at each magnetic field strength.
118584374
Pairing fluctuation effects in a strongly coupled color superfluid/superconductor
We investigate the effects of pairing fluctuations in fermionic superfluids/superconductors where pairing occurs among three species (colors) of fermions. Such color superfluids/superconductors can be realized in three-component atomic Fermi gases and in dense quark matter. The superfluidity/superconductivity is characterized by a three-component order parameter which denotes the pairing among the three colors of fermions. Due to the SU$(3)$ symmetry of the Hamiltonian, one color does not participate pairing. This branch of fermionic excitation is gapless in the naive BCS mean-field description. In this paper, we adopt a pairing-fluctuation theory to investigate the pairing fluctuation effects on the unpaired color in strongly coupled atomic color superfluids and quark color superconductors. At low temperature, a large pairing gap of the paired colors suppresses the pairing fluctuation effects for the unpaired color, and the spectral density of the unpaired color shows a single Fermi-liquid peak, which indicates the naive mean-field picture remains valid. As the temperature is increased, the spectral density of the unpaired color generally exhibits a three-peak structure: the Fermi-liquid peak remains but get suppressed, and two pseudogap-like peaks appears. At and above the superfluid transition temperature, the Fermi-liquid peak disappears completely and the all three colors exhibits pseudogap-like spectral density. The coexistence of Fermi liquid and pseudogap behavior is generic for both atomic color superfluids and quark color superconductors.
118625057
BCS-BEC crossover in a relativistic boson-fermion model beyond mean field approximation
We investigate the fluctuation effect of the di-fermion field in the crossover from Bardeen-Cooper-Schrieffer (BCS) pairing to a Bose-Einstein condensate (BEC) in a relativistic superfluid. We work within the boson-fermion model obeying a global U(1) symmetry. To go beyond the mean field approximation we use Cornwall-Jackiw-Tomboulis formalism to include higher-order contributions. The quantum fluctuations of the pairing condensate is provided by bosons in nonzero modes, whose interaction with fermions gives the two-particle-irreducible effective potential. It changes the crossover property in the BEC regime. With the fluctuations the superfluidity phase transition becomes the first order in a grand canonical ensemble. We calculate the condensate, the critical temperature T{sub c} and particle abundances as functions of a crossover parameter of the boson mass.
54619300
Experimental progress in the measurement and control of single atom trajectory
In this review article, the progress and recent developments in the measuring and controlling of single atom trajectories are reviewed. With the development of laser cooling and trapping technology, it is possible to achieve the measurement and control of single atom trajectory experimentally. The experiment of tracking a single atom trajectory with high resolution and the endeavor of eliminating the degeneracy of the trajectories are then introduced.
21572416
Absolute measurement of hadronic branching fractions of the Ds+ meson.
The branching fractions of D(s)(+/-) meson decays serve to normalize many measurements of processes involving charm quarks. Using 298 pb(-1) of e(+)e(-) collisions recorded at a center of mass energy of 4.17 GeV, we determine absolute branching fractions for eight D(s)(+/-) decays with a double tag technique. In particular we determine the branching fraction B(D(s)(+)-->K(-)K(+}pi(+))=(5.50+/-0.23+/-0.16)%, where the uncertainties are statistical and systematic, respectively. We also provide partial branching fractions for kinematic subsets of the K(-)K(+)pi(+) decay mode.
122359606
SOME PROPERTIES OF THIN GAP GAS CHAMBERS
The operation of a thin gap multiwire chamber with a CO2/n-pentane mixture is described for different wire diameters, gap distances and cathode material.
123148774
J/psi and psi(2S) Radiative Decays to eta(c)
117849053
Detecting the ambient neutralino dark matter particles at accelerator
In this work, we present a new strategy to investigate the possibility of direct detection of the ambient neutralino matter at accelerator. We calculate the cross sections for both elastic and inelastic scattering processes of the dark matter particles with the beam particles at $e^+e^-$ and hadron colliders.