995 research outputs found
Quark Mass Textures and sin 2 beta
Recent precise measurements of sin 2 beta from the B-factories (BABAR and
BELLE) and a better known strange quark mass from lattice QCD make precision
tests of predictive texture models possible. The models tested include those
hierarchical N-zero textures classified by Ramond, Roberts and Ross, as well as
any other hierarchical matrix Ansatz with non-zero 12 = 21 and vanishing 11 and
13 elements. We calculate the maximally allowed value for sin 2 beta in these
models and show that all the aforementioned models with vanishing 11 and 13
elements are ruled out at the 3 sigma level. While at present sin 2 beta and
|Vub/Vcb| are equally good for testing N-zero texture models, in the near
future the former will surpass the latter in constraining power.Comment: 1+20 pages, 2 figures, JHEP3 clas
Probing semiclassical analogue gravity in Bose--Einstein condensates with widely tunable interactions
Bose-Einstein condensates (BEC) have recently been the subject of
considerable study as possible analogue models of general relativity. In
particular it was shown that the propagation of phase perturbations in a BEC
can, under certain conditions, closely mimic the dynamics of scalar quantum
fields in curved spacetimes. In two previous articles [gr-qc/0110036,
gr-qc/0305061] we noted that a varying scattering length in the BEC corresponds
to a varying speed of light in the ``effective metric''. Recent experiments
have indeed achieved a controlled tuning of the scattering length in Rubidium
85. In this article we shall discuss the prospects for the use of this
particular experimental effect to test some of the predictions of semiclassical
quantum gravity, for instance, particle production in an expanding universe. We
stress that these effects are generally much larger than the Hawking radiation
expected from causal horizons, and so there are much better chances for their
detection in the near future.Comment: 18 pages; uses revtex4. V2: Added brief discussion of "Bose-Nova"
phenomenon, and appropriate reference
Vacuum Fluctuations, Geometric Modular Action and Relativistic Quantum Information Theory
A summary of some lines of ideas leading to model-independent frameworks of
relativistic quantum field theory is given. It is followed by a discussion of
the Reeh-Schlieder theorem and geometric modular action of Tomita-Takesaki
modular objects associated with the quantum field vacuum state and certain
algebras of observables. The distillability concept, which is significant in
specifying useful entanglement in quantum information theory, is discussed
within the setting of general relativistic quantum field theory.Comment: 26 pages. Contribution for the Proceedings of a Conference on Special
Relativity held at Potsdam, 200
Analysis of the doubly heavy baryons in the nuclear matter with the QCD sum rules
In this article, we study the doubly heavy baryon states ,
, and in the nuclear matter using the QCD
sum rules, and derive three coupled QCD sum rules for the masses, vector
self-energies and pole residues. The predictions for the mass-shifts in the
nuclear matter , , and
can be confronted with the
experimental data in the future.Comment: 10 pages, 4 figure
Analysis of and with QCD sum rules
In this article, we calculate the masses and the pole residues of the
heavy baryons and with the QCD
sum rules. The numerical values (or
) and (or ) are in good agreement
with the experimental data.Comment: 18 pages, 18 figures, slight revisio
Markov Chain Monte Carlo Exploration of Minimal Supergravity with Implications for Dark Matter
We explore the full parameter space of Minimal Supergravity (mSUGRA),
allowing all four continuous parameters (the scalar mass m_0, the gaugino mass
m_1/2, the trilinear coupling A_0, and the ratio of Higgs vacuum expectation
values tan beta) to vary freely. We apply current accelerator constraints on
sparticle and Higgs masses, and on the b -> s gamma branching ratio, and
discuss the impact of the constraints on g_mu-2. To study dark matter, we apply
the WMAP constraint on the cold dark matter density. We develop Markov Chain
Monte Carlo (MCMC) techniques to explore the parameter regions consistent with
WMAP, finding them to be considerably superior to previously used methods for
exploring supersymmetric parameter spaces. Finally, we study the reach of
current and future direct detection experiments in light of the WMAP
constraint.Comment: 16 pages, 4 figure
Search for Global Dipole Enhancements in the HiRes-I Monocular Data above 10^{18.5} eV
Several proposed source models for Ultra-High Energy Cosmic Rays (UHECRs)
consist of dipole distributions oriented towards major astrophysical landmarks
such as the galactic center, M87, or Centaurus A. We use a comparison between
real data and simulated data to show that the HiRes-I monocular data for
energies above 10^{18.5} eV is, in fact, consistent with an isotropic source
model. We then explore methods to quantify our sensitivity to dipole source
models oriented towards the Galactic Center, M87, and Centaurus A.Comment: 17 pages, 31 figure
Observation of the Ankle and Evidence for a High-Energy Break in the Cosmic Ray Spectrum
We have measured the cosmic ray spectrum at energies above eV using
the two air fluorescence detectors of the High Resolution Fly's Eye experiment
operating in monocular mode. We describe the detector, PMT and atmospheric
calibrations, and the analysis techniques for the two detectors. We fit the
spectrum to models describing galactic and extragalactic sources. Our measured
spectrum gives an observation of a feature known as the ``ankle'' near eV, and strong evidence for a suppression near eV.Comment: 14 pages, 9 figures. To appear in Physics Letters B. Accepted versio
Nonlinear effects in resonant layers in solar and space plasmas
The present paper reviews recent advances in the theory of nonlinear driven
magnetohydrodynamic (MHD) waves in slow and Alfven resonant layers. Simple
estimations show that in the vicinity of resonant positions the amplitude of
variables can grow over the threshold where linear descriptions are valid.
Using the method of matched asymptotic expansions, governing equations of
dynamics inside the dissipative layer and jump conditions across the
dissipative layers are derived. These relations are essential when studying the
efficiency of resonant absorption. Nonlinearity in dissipative layers can
generate new effects, such as mean flows, which can have serious implications
on the stability and efficiency of the resonance
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