45,142 research outputs found

    Indirect unitarity violation entangled with matter effects in reactor antineutrino oscillations

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    If finite but tiny masses of the three active neutrinos are generated via the canonical seesaw mechanism with three heavy sterile neutrinos, the 3\times 3 Pontecorvo-Maki-Nakagawa-Sakata neutrino mixing matrix V will not be exactly unitary. This kind of indirect unitarity violation can be probed in a precision reactor antineutrino oscillation experiment, but it may be entangled with terrestrial matter effects as both of them are very small. We calculate the probability of \overline{\nu}_e \to \overline{\nu}_e oscillations in a good analytical approximation, and find that, besides the zero-distance effect, the effect of unitarity violation is always smaller than matter effects, and their entanglement does not appear until the next-to-leading-order oscillating terms are taken into account. Given a 20-kiloton JUNO-like liquid scintillator detector, we reaffirm that terrestrial matter effects should not be neglected but indirect unitarity violation makes no difference, and demonstrate that the experimental sensitivities to the neutrino mass ordering and a precision measurement of \theta_{12} and \Delta_{21} \equiv m^2_2 - m^2_1 are robust.Comment: 21 pages, 6 figures, version to be published in PLB, more discussions adde

    Probing Half-odd Topological Number with Cold Atoms in a Non-Abelian Optical Lattice

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    We propose an experimental scheme to probe the contribution of a single Dirac cone to the Hall conductivity as half-odd topological number sequence. In our scheme, the quantum anomalous Hall effect as in graphene is simulated with cold atoms trapped in an optical lattice and subjected to a laser-induced non-Abelian gauge field. By tuning the laser intensity to change the gauge flux, the energies of the four Dirac points in the first Brillouin zone are shifted with each other and the contribution of the single Dirac cone to the total atomic Hall conductivity is manifested. We also show such manifestation can be experimentally probed with atomic density profile measurements.Comment: 5 pages, 3 figure

    Coupled-channel analysis of the possible D()D()D^{(*)}D^{(*)}, Bˉ()Bˉ()\bar{B}^{(*)}\bar{B}^{(*)} and D()Bˉ()D^{(*)}\bar{B}^{(*)} molecular states

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    We perform a coupled-channel study of the possible deuteron-like molecules with two heavy flavor quarks, including the systems of D()D()D^{(*)}D^{(*)} with double charm, Bˉ()Bˉ()\bar{B}^{(*)}\bar{B}^{(*)} with double bottom and D()Bˉ()D^{(*)}\bar{B}^{(*)} with both charm and bottom, within the one-boson-exchange model. In our study, we take into account the S-D mixing which plays an important role in the formation of the loosely bound deuteron, and particularly, the coupled-channel effect in the flavor space. According to our calculation, the states D()D()[I(JP)=0(1+)]D^{(*)}D^{(*)}[I(J^P)=0(1^+)] and (D()D())s[JP=1+](D^{(*)}D^{(*)})_s[J^P=1^+] with double charm, the states Bˉ()Bˉ()[I(JP)=0(1+),0(2+),1(0+),1(1+),1(2+)]\bar{B}^{(*)}\bar{B}^{(*)}[I(J^P)=0(1^+),0(2^+),1(0^+),1(1^+),1(2^+)], (Bˉ()Bˉ())s[JP=0+,1+,2+](\bar{B}^{(*)}\bar{B}^{(*)})_s[J^P=0^+,1^+,2^+] and (Bˉ()Bˉ())ss[JP=0+,1+,2+](\bar{B}^{(*)}\bar{B}^{(*)})_{ss}[J^P=0^+,1^+,2^+] with double bottom, and the states D()Bˉ()[I(JP)=0(0+),0(1+)]D^{(*)}\bar{B}^{(*)}[I(J^P)=0(0^+),0(1^+)] and (D()Bˉ())s[JP=0+,1+](D^{(*)}\bar{B}^{(*)})_s[J^P=0^+,1^+] with both charm and bottom are good molecule candidates. However, the existence of the states D()D()[I(JP)=0(2+)]D^{(*)}D^{(*)}[I(J^P)=0(2^+)] with double charm and D()Bˉ()[I(JP)=1(1+)]D^{(*)}\bar{B}^{(*)}[I(J^P)=1(1^+)] with both charm and bottom is ruled out.Comment: 1 figure added, published in Physical Review

    Isospin effect on nuclear stopping in intermediate energy Heavy Ion Collisions

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    By using the Isospin Dependent Quantum Molecular Dynamics Model (IQMD), we study the dependence of nuclear stopping Q_{ZZ}/A and R in intermediate energy heavy ion collisions on system size, initial N/Z, isospin symmetry potential and the medium correction of two-body cross sections. We find the effect of initial N/Z ratio, isospin symmetry potential on stopping is weak. The excitation function of Q_{ZZ}/A and R depends on the form of medium correction of two-body cross sections, the equation of state of nuclear matter (EOS). Our results show the behavior of the excitation function of Q_{ZZ}/A and R can provide clearer information of the isospin dependence of the medium correction of two-body cross sections.Comment: 3 pages including 4 figure
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