633 research outputs found
Modification of the Unitarity Relation for sin2beta-Vub in Supersymmetric Models
Recently, a more than 2sigma discrepancy has been observed between the well
measured inclusive value of Vub and the predicted value of Vub from the
unitarity triangle fit using the world average value of sin2beta. We attempt to
resolve this tension in the context of grand unified SO(10) and SU(5) models
where the neutrino mixing matrix is responsible for flavor changing neutral
current at the weak scale and the models with non-proportional A-terms (can be
realized simply in the context of intersecting D-brane models) and investigate
the interplay between the constraints arising from B_{s,d}-\bar B_{s,d}
mixings, epsilon_K, Br(tau -> mu gamma), Br(mu -> e gamma) and a fit of this
new discrepancy. We also show that the ongoing measurement of the phase of Bs
mixing will be able to identify the grand unified model. The measurement of
Br(tau -> e gamma) will also be able to test these scenarios, especially the
models with non-proportional A-terms.Comment: 20 pages, 4 figures. Minor corrections, references adde
Correlation between direct dark matter detection and Br(B_s -> mu mu) with a large phase of B_s - anti-B_s mixing
We combine the analyses for flavor changing neutral current processes and
dark matter solutions in minimal-type supersymmetric grand unified theory (GUT)
models, SO(10) and SU(5), with a large B_s - anti-B_s mixing phase and large
tan beta. For large tan beta, the double penguin diagram dominates the SUSY
contribution to the B_s - anti-B_s mixing amplitude. Also, the Br(B_s -> mu mu)
constraint becomes important as it grows as tan^6 beta, although it can still
be suppressed by large pseudoscalar Higgs mass m_A. We investigate the
correlation between B_s -> mu mu and the dark matter direct detection
cross-section through their dependence on m_A. In the minimal-type of SU(5)
with type I seesaw, the large mixing in neutrino Dirac couplings results in
large lepton flavor violating decay process tau to mu gamma, which in turn sets
upper bound on m_A. In the SO(10) case, the large mixing can be chosen to be in
the Majorana couplings instead, and the constraint from Br(tau -> mu gamma) can
be avoided. The heavy Higgs funnel region turns out to be an interesting
possibility in both cases and the direct dark matter detection should be
possible in the near future in these scenarios.Comment: 19 pages, 8 figure
Suppressing Proton Decay in the Minimal SO(10) Model
We show that in a class of minimal supersymmetric SO(10) models which have
been found to be quite successful in predicting neutrino mixings, all proton
decay modes can be suppressed by a particular choice of Yukawa textures. This
suppression works for contributions from both left and right operators for
nucleon decay and for arbitrary \tan\beta. The required texture not only fits
all lepton and quark masses as well as CKM parameters but it also predicts
neutrino mixing parameter U_e3 and Dirac CP phase \sin|\delta_MNS| to be
0.07-0.09 and 0.3-0.7 respectively. We also discuss the relation between the
GUT symmetry breaking parameters for the origin of these textures.Comment: 7 pages, 2 figure
Decontamination of a rotating cutting tool during operation by means of atmospheric pressure plasmas
Multiple peak aggregations for the Keller-Segel system
In this paper we derive matched asymptotic expansions for a solution of the
Keller-Segel system in two space dimensions for which the amount of mass
aggregation is , where Previously available asymptotics
had been computed only for the case in which N=1
X-Ray Diffraction Study of CeT2Al10 (T = Ru, Os) at Low Temperatures and under Pressures
We have carried out a powder X-ray diffraction investigation on antiferromagnetic Kondo semiconductorsCeRu2Al10 and CeOs2Al10 at low temperatures and under high pressures as well as the structural investigationon single crystal of these compounds. The results of powder X-ray studies of CeRu2Al10 and CeOs2Al10 indicatethat these compounds do not have structural transition at its antiferromagnetic ordering temperature. The resultsof single crystal structural refinement indicate that the b-axis of this crystal structure is insensitive not only topressure but also to temperature and that the effect of cooling to Ce–Ce distance for CeRu2Al10 is the same asthat for CeOs2Al10
Rooting for phylogenetic networks
This paper studies the relationship between undirected (unrooted) and
directed (rooted) phylogenetic networks. We describe a polynomial-time
algorithm for deciding whether an undirected binary phylogenetic network, given
the locations of the root and reticulation vertices, can be oriented as a
directed phylogenetic network. Moreover, we give a mathematical
characterization of when this is the case and show that this directed
phylogenetic network is then always unique. These results are generalized to
the nonbinary case. In addition, we describe an algorithm for deciding whether
an undirected binary phylogenetic network can be oriented as a directed
phylogenetic network of a certain class. The algorithm is fixed-parameter
tractable (FPT) when the parameter is the level of the network and is
applicable to a wide range of network classes, including tree-child,
tree-based, stack-free and orchard networks. It can also be used to decide
whether an undirected phylogenetic network is tree-based and whether a
partly-directed phylogenetic network can be oriented as a directed phylogenetic
network. Finally, we show that, in general, it is NP-hard to decide whether an
undirected network can be oriented as a tree-based network
CANGAROO-III Search for Gamma Rays from SN 1987A and the Surrounding Field
Optical images of SN 1987A show a triple ring structure. The inner (dust)
ring has recently increased in brightness and in the number of hot spots
suggesting that the supernova shock wave has collided with the dense
pre-existing circumstellar medium, a scenario supported by radio and X-ray
observations. Such a shocked environment is widely expected to result in the
acceleration of charged particles, and the accompanying emission of very high
energy gamma-rays. Here, we report the results of observations made in 2004 and
2006 which yield upper limits on the TeV gamma-ray flux, which are compared
with a theoretical prediction. In addition, we set upper limits on the TeV flux
for four high energy objects which are located within the same field of view of
the observation: the super-bubble 30 Dor C, the Crab-like pulsar PSR
B054069, the X-ray binary LMC X-1, and the supernova remnant N157B.Comment: 5 pages, 5 figures, Accepted for publication in Ap
Flat-band ferromagnetism induced by off-site repulsions
Density matrix renormalization group method is used to analyze how the
nearest-neighbor repulsion V added to the Hubbard model on 1D triangular
lattice and a railway trestle (t-t') model will affect the electron-correlation
dominated ferromagnetism arising from the interference (frustration). Obtained
phase diagram shows that there is a region in smaller-t' side where the
critical on-site repulsion above which the system becomes ferromagnetic is
reduced when the off-site repulsion is introduced.Comment: 4 pages, RevTex, 6 figures in Postscript, to be published in Phys.
Rev.
- …