39 research outputs found
The Three-body Force and the Tetraquark Interpretation of Light Scalar Mesons
We study the possible tetraquark interpretation of light scalar meson states
, , , within the framework of the
non-relativistic potential model. The wave functions of tetraquark states are
obtained in a space spanned by multiple Gaussian functions. We find that the
mass spectra of the light scalar mesons can be well accommodated in the
tetraquark picture if we introduce a three-body quark interaction in the quark
model. Using the obtained multiple Gaussian wave functions, the decay constants
of tetraquarks are also calculated within the ``fall apart'' mechanism
Phase space constraints and statistical jet studies in heavy-ion collisions
The effect of the correlation induced by global momentum conservation on the
two-particle distribution in nucleus-nucleus collisions is discussed, with a
focus on the generic case of collisions with a non-vanishing impact parameter.Comment: 5 pages, invited talk at the RHIC & AGS Annual Users' Meeting,
Brookhaven Nat. Lab. (USA) and at the EPS HEP 2007 Conference, Manchester
(UK
The dispersive contribution of decays and X(1576)
We study whether the broad enhancement X(1576) arises from the final state
interaction (FSI) of decays. We
consider both the absorptive and dispersive contribution of the above
amplitudes since the intermediate states are very close to .
The same mechanism leads to a similar enhancement around 1580 MeV in the
spectrum in the channel, which
can be used to test whether X(1576) can be ascribed to the FSI effect of
.Comment: 4 pages, 4 figure
Neutrinos and Future Concordance Cosmologies
We review the free parameters in the concordance cosmology, and those which
might be added to this set as the quality of astrophysical data improves. Most
concordance parameters encode information about otherwise unexplored aspects of
high energy physics, up to the GUT scale via the "inflationary sector," and
possibly even the Planck scale in the case of dark energy. We explain how
neutrino properties may be constrained by future astrophysical measurements.
Conversely, future neutrino physics experiments which directly measure these
parameters will remove uncertainty from fits to astrophysical data, and improve
our ability to determine the global properties of our universe.Comment: Proceedings of paper given at Neutrino 2008 meeting (by RE
Study of Pure Annihilation Decays B_{d,s} \to D^{0} \bar D^{0}
With heavy quark limit and hierarchy approximation , we analyze the and decays, which
occur purely via annihilation type diagrams. As a roughly estimation, we
calculate their branching ratios and CP asymmetries in Perturbative QCD
approach. The branching ratio of is about
that is just below the latest experimental upper limit. The branching ratio of
is about , which could be measured in
LHC-b. From the calculation, it could be found that this branching ratio is not
sensitive to the weak phase angle . In these two decay modes, there
exist CP asymmetries because of interference between weak and strong
interaction. However, these asymmetries are too small to be measured easily.Comment: 13 pages, 4 figure
Neutrino Masses and Lepton-flavor-violating Decays in the Supersymmetric Left-right Model
In the supersymmetric left-right model, the light neutrino masses are given
by the Type-II seesaw mechanism. A duality property about this mechanism
indicates that there exist eight possible Higgs triplet Yukawa couplings which
result in the same neutrino mass matrix. In this paper, We work out the
one-loop renormalization group equations for the effective neutrino mass matrix
in the supersymmetric left-right model. The stability of the Type-II seesaw
scenario is briefly discussed. We also study the lepton-flavor-violating
processes ( and ) by using the
reconstructed Higgs triplet Yukawa couplings
Lightest sterile neutrino abundance within the nuMSM
We determine the abundance of the lightest (dark matter) sterile neutrinos
created in the Early Universe due to active-sterile neutrino transitions from
the thermal plasma. Our starting point is the field-theoretic formula for the
sterile neutrino production rate, derived in our previous work [JHEP
06(2006)053], which allows to systematically incorporate all relevant effects,
and also to analyse various hadronic uncertainties. Our numerical results
differ moderately from previous computations in the literature, and lead to an
absolute upper bound on the mixing angles of the dark matter sterile neutrino.
Comparing this bound with existing astrophysical X-ray constraints, we find
that the Dodelson-Widrow scenario, which proposes sterile neutrinos generated
by active-sterile neutrino transitions to be the sole source of dark matter, is
only possible for sterile neutrino masses lighter than 3.5 keV (6 keV if all
hadronic uncertainties are pushed in one direction and the most stringent X-ray
bounds are relaxed by a factor of two). This upper bound may conflict with a
lower bound from structure formation, but a definitive conclusion necessitates
numerical simulations with the non-equilibrium momentum distribution function
that we derive. If other production mechanisms are also operative, no upper
bound on the sterile neutrino mass can be established.Comment: 34 pages. v2: clarifications and a reference added; published
version. v3: erratum appende
Signatures of black holes at the LHC
Signatures of black hole events at CERN's Large Hadron Collider are
discussed. Event simulations are carried out with the Fortran Monte Carlo
generator CATFISH. Inelasticity effects, exact field emissivities, color and
charge conservation, corrections to semiclassical black hole evaporation,
gravitational energy loss at formation and possibility of a black hole remnant
are included in the analysis.Comment: 13 pages, 7 figure
An Investigation of Hadronization Mechanism at Factory
We briefly review the hadronization pictures adopted in the LUND String
Fragmentation Model(LSFM), Webber Cluster Fragmentation Model(WCFM) and Quark
Combination Model(QCM), respectively. Predictions of hadron multiplicity,
baryon to meson ratios and baryon-antibaryon flavor correlations, especially
related to heavy hadrons at factory obtained by LSFM and QCM are
reported.Comment: 18 pages, 6 figures. accepted by Sci China Phys Mech Astro
Associated production of the scalars and new gauge bosons from a little Higgs model at the LHC
The littlest Higgs model with T-parity ( model) predicts the existence
of the T-odd scalars (, , and ). We consider
production of these new particles associated with T-odd gauge bosons at the
. We find that the partonic process can
generate a number of the characteristic signal events with a charged lepton and
large missing energy at the .Comment: 11 pages, 3 figure