71,093 research outputs found
New constraints on a light CP-odd Higgs boson and related NMSSM Ideal Higgs Scenarios
Recent BaBar limits on \br(\Upsilon(3S)\to \gam a\to \gam \tau^+\tau^-) and
\br(\Upsilon(3S)\to \gam a\to \gam \mu^+\mu^-) provide increased constraints
on the a b\anti b coupling of a CP-odd Higgs boson, , with
. We extract these limits from the BaBar data and compare
to the limits previously obtained using other data sets, especially the
CLEO-III \br(\Upsilon(1S)\to \gam\to\tau^+\tau^-) limits. Comparisons are
made to predictions in the context of "ideal"-Higgs NMSSM scenarios, in which
the lightest CP-even Higgs boson, , can have mass below 105\gev (as
preferred by precision electroweak data) and yet can escape old LEP limits by
virtue of decays to a pair of the lightest CP-odd Higgs bosons, , with . Most such scenarios with are
eliminated, but the bulk of the m_{a_1}>7.5\gev scenarios, which are
theoretically the most favored, survive. We also outline the impact of the new
ALEPH LEP results in the \epem\to Z+4\tau channel. For ,
only NMSSM ideal Higgs scenarios with m_{h_1}\gsim 98\gev and close
to satisfy the ALEPH limits. For \tan\beta\lsim 2, the ALEPH limits
are easily satisfied for the most theoretically preferred NMSSM scenarios,
which are those with close to and m_{h_1}\sim
90\gev-100\gev.Comment: 24 pages, 25 figures, paper updated to incorporate final ALEPH limits
in Z+4\tau channel
Ab initio study of a mechanically gated molecule: From weak to strong correlation
The electronic spectrum of a chemically contacted molecule in the junction of
a scanning tunneling microscope can be modified by tip retraction. We analyze
this effect by a combination of density functional, many-body perturbation and
numerical renormalization group theory, taking into account both the
non-locality and the dynamics of electronic correlation. Our findings, in
particular the evolution from a broad quasiparticle resonance below to a narrow
Kondo resonance at the Fermi energy, correspond to the experimental
observations.Comment: 4 pages, 3 figure
Isolated Galaxies versus Interacting Pairs with MaNGA
We present preliminary results of the spectral analysis on the radial
distributions of the star formation history in both, a galaxy merger and a
spiral isolated galaxy observed with MaNGA. We find that the central part of
the isolated galaxy is composed by older stellar population (2 Gyr) than
in the outskirts (7 Gyr). Also, the time-scale is gradually larger from 1
Gyr in the inner part to 3 Gyr in the outer regions of the galaxy. In the case
of the merger, the stellar population in the central region is older than in
the tails, presenting a longer time-scale in comparison to central part in the
isolated galaxy. Our results are in agreement with a scenario where spiral
galaxies are built from inside-out. In the case of the merger, we find evidence
that interactions enhance star formation in the central part of the galaxy.Comment: 7 pages, 2 figures. Proceedings of the EWASS-2015 special session
Sp3, accepted for publication in Special Issue "3D View on Interacting and
Post-Interacting Galaxies from Clusters to Voids" of open access journal
"Galaxies
Exact Potts Model Partition Functions for Strips of the Honeycomb Lattice
We present exact calculations of the Potts model partition function
for arbitrary and temperature-like variable on -vertex
strip graphs of the honeycomb lattice for a variety of transverse widths
equal to vertices and for arbitrarily great length, with free
longitudinal boundary conditions and free and periodic transverse boundary
conditions. These partition functions have the form
, where
denotes the number of repeated subgraphs in the longitudinal direction. We give
general formulas for for arbitrary . We also present plots of
zeros of the partition function in the plane for various values of and
in the plane for various values of . Explicit results for partition
functions are given in the text for (free) and (cylindrical),
and plots of partition function zeros are given for up to 5 (free) and
(cylindrical). Plots of the internal energy and specific heat per site
for infinite-length strips are also presented.Comment: 39 pages, 34 eps figures, 3 sty file
Damping of antiferromagnetic spin waves by valence fluctuations in the double layer perovskite YBaFe2O5
Inelastic neutron scattering experiments show that spin dynamics in the
charge ordered insulating ground state of the double-layer perovskite YBaFe2O5
is well described in terms of eg superexchange interactions. Above the Verwey
transition at TV = 308 K, t2g double exchange-type conduction within
antiferromagnetic FeO2--BaO--FeO2 double layers proceeds by an electron hopping
process that requires a spin flip of the five-fold coordinated Fe ions, costing
an energy 5S^2 of approximately 0.1 eV. The hopping process disrupts
near-neighbor spin correlations, leading to massive damping of zone-boundary
spin waves.Comment: RevTeX, 4 pages, 4 figures, submitted to Phys. Rev. Let
The strong-CP question in SU(3)_c X SU(3)_L X U(1)_N models
We analyze two recent models based on the gauge group
SU(3)SU(3)U(1) where each generation is not
anomaly-free, but anomaly cancels when three generations are taken into
account. We show that the most general Yukawa couplings of these models admit
of a Peccei-Quinn symmetry. This symmetry can be extended to the entire
Lagrangian by using extra fields in a very elegant way so that the resulting
axion can be made invisible.Comment: Latex, 8 pages, no figure
The Neutron Electric Dipole Moment and CP-violating Couplings in the Supersymmetric Standard Model without R-parity
We analyze the neutron electric dipole moment (EDM) in the Minimal
Supersymmetric Model with explicit R-parity violating terms. The leading
contribution to the EDM occurs at the 2-loop level and is dominated by the
chromoelectric dipole moments of quarks, assuming there is no tree-level
mixings between sleptons and Higgs bosons or between leptons and gauginos.
Based on the experimental constraint on the neutron EDM, we set limits on the
imaginary parts of complex couplings and
due to the virtual b-loop or tau-loop.Comment: final manuscript to appear in Phys. Rev. D, 15 pages, latex, 4
figures include
Modeling and Analysis of Power Processing Systems (MAPPS). Volume 2: Appendices
The computer programs and derivations generated in support of the modeling and design optimization program are presented. Programs for the buck regulator, boost regulator, and buck-boost regulator are described. The computer program for the design optimization calculations is presented. Constraints for the boost and buck-boost converter were derived. Derivations of state-space equations and transfer functions are presented. Computer lists for the converters are presented, and the input parameters justified
Heterodyne detection of the 752.033-GHz H2O rotational absorption line
A tunable high resolution two stage heterodyne radiometer was developed for the purpose of investigating the intensity and lineshape of the 752.033 GHz rotational transition of water vapor. Single-sideband system noise temperatures of approximately 45,000 K were obtained using a sensitive GaAs Schottky diode as the first stage mixer. First local oscillator power was supplied by a CO2 laser pumped formic acid laser (761.61 GHz), generating an X-band IF signal with theoretical line center at 9.5744 GHz. Second local oscillator power was provided by means of a 3 GHz waveguide cavity filter with only 9 dB insertion loss. In absorption measurements of the H2O taken from a laboratory simulation of a high altitude rocket plume, the center frequency of the 752 GHz line was determined to within 1 MHz of the reported value. A rotational temperature 75 K, a linewidth 5 MHz and a Doppler shift 3 MHz were measured with the line-of-sight intersecting the simulated-plume axis at a distance downstream of 30 nozzle diameters. These absorption data were obtained against continuum background radiation sources at temperatures of 1175 and 300 K
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