2,197 research outputs found
New Particles from Belle
I report recent results on hidden charm spectroscopy from Belle. These
include: observation of a near-threshold enhancement in the omega-J/psi
invariant mass distribution for exclusive B-->K omega J/psi decays; evidence
for the decay X(3872)-->pi+pi-pi0 J/psi, where the pi+pi-pi0 invariant mass
distribution has a strong peak between 750 MeV and the kinematic limit of 775
MeV, suggesting that the process is dominated by the sub-threshold decay
X-->omega J/psi; and the observation of a peak near 3940 MeV in the J/psi
recoil mass spectrum for the inclusive continuum process e+e- --> J/psi X. The
results are based on a study of a 287 fb-1 sample of e+e- annihilation data
collected at center- of-mass energies around the Upsilon(4S) in the Belle
detector at the KEKB collider.Comment: 10 pages 12 figures. Invited talk at the 1st meeting of the APS
Topical Group on Hadronic Physics, Fermilab, October 24-26, 2004; revised to
correct some reference
EM Decay of X(3872) as the charmonium
The recently BaBar results raise the possibility that X(3872) has negative
parity. This makes people reconsider assigning X(3872) to the state. In this paper we give a general form of the wave function of
mesons. By solving the instantaneous Bethe-Salpeter equation, we get
the mass spectrum and corresponding wave functions. We calculate
electromagnetic decay widths of the first state which we assume to be
the X(3872) particle. The results are keV, eV and keV. The ratio of branch fractions
of the second and first channel is about 0.002, which is inconsistent with the
experimental value . So X(3872) is unlikely to be a
charmonium state. In addition, we obtain a relatively large decay width for
channel which is keV.Comment: Revised versio
Faddeev study of heavy baryon spectroscopy
We investigate the structure of heavy baryons containing a charm or a bottom
quark. We employ a constituent quark model successful in the description of the
baryon-baryon interaction which is consistent with the light baryon spectra. We
solve exactly the three-quark problem by means of the Faddeev method in
momentum space. Heavy baryon spectrum shows a manifest compromise between
perturbative and nonperturbative contributions. The flavor dependence of the
one-gluon exchange is analyzed. We assign quantum numbers to some already
observed resonances and we predict the first radial and orbital excitations of
all states with or 3/2. We combine our results with heavy quark
symmetry and lowest-order SU(3) symmetry breaking to predict the masses and
quantum numbers of six still non-measured ground-state beauty baryons.Comment: 22 pages, 4 figures, 8 tables. Accepted for publication in J. Phys.
B \to K(K^*) missing energy in Unparticle physics
In the present work we study the effects of an unparticle \unpart as the
possible source of missing energy in the decay . We find that the dependence of the differential branching ratio on
the ()-meson's energy in the presence of the vector unparticle
operators is very distinctive from that of the SM. Moreover, in using the
existing upper bound on decays, we have
been able to put more stringent constraints on the parameters of unparticle
stuff.Comment: 13 pages, 5 figure
Measurement of the Surface Gravity of Boo
Direct angular size measurements of the G0IV subgiant Boo from the
Palomar Testbed Interferometer are presented, with limb-darkened angular size
of mas, which indicate a linear
radius of . A bolometric flux estimate of erg cms is computed, which indicates
an effective temperature of K and luminosity of for this object. Similar data are established for a check
star, HD 121860. The Boo results are compared to, and confirm, similar
parameters established by the {\it MOST} asteroseismology satellite. In
conjunction with the mass estimate from the {\it MOST} investigation, a surface
gravity of [cm s] is established for
Boo.Comment: To appear in March 1, 2007 ApJ v657 n
A 15 year slow-slip event on the Sunda megathrust offshore Sumatra
In the Banyak Islands of Sumatra, coral microatoll records reveal a 15 year-long reversal of interseismic vertical displacement from subsidence to uplift between 1966 and 1981. To explain these coral observations, we test four hypotheses, including regional sea level changes and various tectonic mechanisms. Our results show that the coral observations likely reflect a 15 year-long slow-slip event (SSE) on the Sunda megathrust. This long-duration SSE exceeds the duration of previously reported SSEs and demonstrates the importance of multidecade geodetic records in illuminating the full spectrum of megathrust slip behavior at subduction zones
Fundamental Properties of Cool Stars with Interferometry
We present measurements of fundamental astrophysical properties of nearby,
low-mass, K- and M-dwarfs from our DISCOS survey (DIameterS of COol Stars). The
principal goal of our study is the determination of linear radii and effective
temperatures for these stars. We calculate their radii from angular diameter
measurements using the CHARA Array and Hipparcos distances. Combined with
bolometric flux measurements based on literature photometry, we use our angular
diameter results to calculate their effective surface temperatures. We present
preliminary results established on an assortment of empirical relations to the
stellar effective temperature and radius that are based upon these
measurements. We elaborate on the discrepancy seen between theoretical and
observed stellar radii, previously claimed to be related to stellar activity
and/or metallicity. Our preliminary conclusion, however, is that convection
plays a larger role in the determination of radii of these late-type stars.
Understanding the source of the radius disagreement is likely to impact other
areas of study for low-mass stars, such as the detection and characterization
of extrasolar planets in the habitable zones.Comment: Contribution to Proceedings of Cool Stars 16 Workshop; 8 pages in ASP
format; 9 figure
Heavy Quark Spectroscopy -- Theory Overview
Some recent discoveries in the spectroscopy of hadrons containing heavy
quarks, and some of their theoretical interpretations, are reviewed.Comment: 13 pages, 6 figures. Presented at Second Meeting of APS Topical Group
on Hadron Physics, Nashville, TN, 22-24. Proceedings to be published by
Journal of Physics (UK), Conference Series. Uses jpconf.cls, jpconf11.clo.
Some corrections; references update
Visualization and spectral synthesis of rotationally distorted stars
Simple spherical, non-rotating stellar models are inadequate when describing
real stars in the limit of very fast rotation: Both the observable spectrum and
the geometrical shape of the star deviate strongly from simple models. We
attempt to approach the problem of modeling geometrically distorted, rapidly
rotating stars from a new angle: By constructing distorted geometrical models
and integrating standard stellar models with varying temperature, gravity, and
abundances, over the entire surface, we attempt a semi-empirical approach to
modeling. Here we present our methodology, and present simple examples of
applications.Comment: 7 pages, 5 figures. Contribution to GREAT-ESF Workshop on "Stellar
Atmospheres in the Gaia Era", Brussels 23-24 June 201
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