440 research outputs found
The Abelian/Nonabelian Correspondence and Frobenius Manifolds
We propose an approach via Frobenius manifolds to the study (began in
math.AG/0407254) of the relation between rational Gromov-Witten invariants of
nonabelian quotients X//G and those of the corresponding ``abelianized''
quotients X//T, for T a maximal torus in G. The ensuing conjecture expresses
the Gromov-Witten potential of X//G in terms of the potential of X//T. We prove
this conjecture when the nonabelian quotients are partial flag manifolds.Comment: 35 pages, no figure
A Detailed Monte-Carlo Simulation for the Belle TOF System
We have developed a detailed Monte Carlo simulation program for the Belle TOF
system. Based on GEANT simulation, it takes account of all physics processes in
the TOF scintillation counters and readout electronics. The simulation
reproduces very well the performance of the Belle TOF system, including the
dE/dx response, the time walk effect, the time resolution, and the hit
efficiency due to beam background. In this report, we will describe the Belle
TOF simulation program in detail.Comment: To be submitted to NI
Iterative Methods and Dynamics for Nonlinear Problems
Kim, Y.; Cordero Barbero, A.; Sharma, J.; Soleymani, F.; Torregrosa Sánchez, JR.; Wang, X. (2017). Iterative Methods and Dynamics for Nonlinear Problems. Discrete Dynamics in Nature and Society. 1-1. doi:10.1155/2017/8592140S1
Ferromagnetism and giant magnetoresistance in the rare earth fullerides Eu6-xSrxC60
We have studied crystal structure, magnetism and electric transport
properties of a europium fulleride Eu6C60 and its Sr-substituted compounds,
Eu6-xSrxC60. They have a bcc structure, which is an isostructure of other M6C60
(M represents an alkali atom or an alkaline earth atom). Magnetic measurements
revealed that magnetic moment is ascribed to the divalent europium atom with S
= 7/2 spin, and a ferromagnetic transition was observed at TC = 10 - 14 K. In
Eu6C60, we also confirm the ferromagnetic transition by heat capacity
measurement. The striking feature in Eu6-xSrxC60} is very large negative
magnetoresistance at low temperature; the resistivity ratio \rho(H = 9
T)/\rho(H = 0 T) reaches almost 10^{-3} at 1 K in Eu6C60. Such large
magnetoresistance is the manifestation of a strong pi-f interaction between
conduction carriers on C60 and 4f electrons of Eu.Comment: 5 pages, 4 figure
Nucleosynthesis Constraints on a Massive Gravitino in Neutralino Dark Matter Scenarios
The decays of massive gravitinos into neutralino dark matter particles and
Standard Model secondaries during or after Big-Bang nucleosynthesis (BBN) may
alter the primordial light-element abundances. We present here details of a new
suite of codes for evaluating such effects, including a new treatment based on
PYTHIA of the evolution of showers induced by hadronic decays of massive,
unstable particles such as a gravitino. We also develop an analytical treatment
of non-thermal hadron propagation in the early universe, and use this to derive
analytical estimates for light-element production and in turn on decaying
particle lifetimes and abundances. We then consider specifically the case of an
unstable massive gravitino within the constrained minimal supersymmetric
extension of the Standard Model (CMSSM). We present upper limits on its
possible primordial abundance before decay for different possible gravitino
masses, with CMSSM parameters along strips where the lightest neutralino
provides all the astrophysical cold dark matter density. We do not find any
CMSSM solution to the cosmological Li7 problem for small m_{3/2}. Discounting
this, for m_{1/2} ~ 500 GeV and tan beta = 10 the other light-element
abundances impose an upper limit m_{3/2} n_{3/2}/n_\gamma < 3 \times 10^{-12}
GeV to < 2 \times 10^{-13} GeV for m_{3/2} = 250 GeV to 1 TeV, which is similar
in both the coannihilation and focus-point strips and somewhat weaker for tan
beta = 50, particularly for larger m_{1/2}. The constraints also weaken in
general for larger m_{3/2}, and for m_{3/2} > 3 TeV we find a narrow range of
m_{3/2} n_{3/2}/n_\gamma, at values which increase with m_{3/2}, where the Li7
abundance is marginally compatible with the other light-element abundances.Comment: 74 pages, 40 Figure
Precise measurement of hadronic tau-decays with an eta meson
We have studied hadronic tau decay modes involving an eta meson using 490
fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy
e+e- collider. The following branching fractions have been measured: B(tau- ->
K- eta nu)=(1.58 +- 0.05 +- 0.09)x 10^{-4}, B(tau- -> K- pi0 eta nu)=(4.6 +-
1.1 +- 0.4)x 10^{-5}, B(tau- -> pi- pi0 eta nu)=(1.35 +- 0.03 +- 0.07)x
10^{-3}, B(tau- -> pi- KS eta nu)=(4.4 +- 0.7 +- 0.2)x 10^{-5}, and B(tau- ->
K^{*-} eta nu)=(1.34 +- 0.12 +- 0.09)x 10^{-4}. These results are substantially
more precise than previous measurements. The new measurements are compared with
theoretical calculations based on the CVC hypothesis or the chiral perturbation
theory. We also set upper limits on branching fractions for tau decays into K-
KS eta nu, pi- KS pi0 eta nu, K- eta eta nu, pi- eta eta nu and non-resonant K-
pi^0 eta nu final states.Comment: 24 pages, 7 figure
Search for B+ -> D*+ pi0 decay
We report on a search for the doubly Cabibbo suppressed decay B+ -> D*+ pi0,
based on a data sample of 657 million BBbar pairs collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric energy e+ e- collider.
We find no significant signal and set an upper limit of Br(B+ -> D*+ pi0) < 3.6
x 10^-6 at the 90% confidence level. This limit can be used to constrain the
ratio between suppressed and favored B -> D* pi decay amplitudes, r < 0.051, at
the 90% confidence level.Comment: 5pages, 2figures, submitted to PRL (v1); PRL published version (v2:
minor corrections in the text
Measurement of CP asymmetry in Cabibbo suppressed D0 decays
We measure the CP-violating asymmetries in decays to the D0 -> K+K- and D0 ->
pi+pi- CP eigenstates using 540 fb^{-1} of data collected with the Belle
detector at or near the Upsilon(4S) resonance. Cabibbo-favored D0 -> K-pi+
decays are used to correct for systematic detector effects. The results,
A_{CP}^{KK} = (-0.43 +- 0.30 +- 0.11)% and A_{CP}^{pipi} = (+0.43 +- 0.52 +-
0.12)%, are consistent with no CP violation.Comment: Submitted to Phys. Lett.
Observation of the and the Y(2175) in
The cross sections for and e^+ e^- \to \phi
\fzero are measured from threshold to using
initial state radiation. The analysis is based on a data sample of 673
fb collected on and below the resonance with the Belle
detector at the KEKB asymmetric-energy collider. First measurements
are reported for the resonance parameters of the in the
mode: MeV/ and MeV/. A structure at ,
corresponding to the so called Y(2175), is observed; its mass and width are
determined to be MeV/ and , respectively.Comment: 11 pages, 6 figures. Add one plot. Accepted by Phys.Rev.D(RC
Optical symmetries and anisotropic transport in high-Tc superconductors
A simple symmetry analysis of in-plane and out-of-plane transport in a family
of high temperature superconductors is presented. It is shown that generalized
scaling relations exist between the low frequency electronic Raman response and
the low frequency in-plane and out-of-plane conductivities in both the normal
and superconducting states of the cuprates. Specifically, for both the normal
and superconducting state, the temperature dependence of the low frequency
Raman slope scales with the axis conductivity, while the
Raman slope scales with the in-plane conductivity. Comparison with experiments
in the normal state of Bi-2212 and Y-123 imply that the nodal transport is
largely doping independent and metallic, while transport near the BZ axes is
governed by a quantum critical point near doping holes per
CuO plaquette. Important differences for La-214 are discussed. It is also
shown that the axis conductivity rise for is a consequence of
partial conservation of in-plane momentum for out-of-plane transport.Comment: 16 pages, 8 Figures (3 pages added, new discussion on pseudogap and
charge ordering in La214
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