879 research outputs found
Study of Bs-> \phi l^+ l^-$ Decay in a Single Universal Extra Dimension
Utilizing form factors calculated within the light-cone sum rules, we have
evaluated the decay branching ratios of and in a single universal extra dimension model (UED), which is
viewed as one of the alternative theories beyond the standard model (SM). For
the decay , the dilepton invariant mass spectra, the
forward-backward asymmetry, and double lepton polarization are also calculated.
For each case, we compared the obtained results with predictions of the SM. In
lower values of the compactification factor 1/R, the only parameter in this
model, we see the considerable discrepancy between the UED and SM models.
However, when 1/R increases, the results of UED tend to diminish and at , two models have approximately the same predictions.
Compared with data from CDF of , the 1/R tends to be
larger than . We also note that the zero crossing point of
the forward-backward asymmetry is become smaller, which will be an important
plat to prob the contribution from the extra dimension model. The results
obtained in this work will be very useful in searching new physics beyond SM.
Moreover, the order of magnitude for branching ratios shows a possibility to
study these channels at the Large Hadron Collider (LHC), CDF and the future
super-B factory.Comment: 13 pages, 16 figure
Charmed Strange Pentaquarks in the Large Limit
The properties of pentaquarks containing a heavy anti-quark and strange
quarks are studied in the bound state picture. In the flavor SU(3) limit, there
are many pentaquark states with the same binding energy. When the SU(3)
symmetry breaking effects are included, however, three states become
particularly stable due to a ``Gell-Mann--Okubo mechanism''. They are the and states discussed by Lipkin, and a a previously
unstudied state. These states will have and
their masses are estimated. These states, if exist, may be seen in experiments
in the near future.Comment: 12 pages in REVTeX, no figure
Higher meson resonances in and
The role of higher meson resonances with spin 1 and 2 is investigated
quantitatively in the decay processes of and
. Among the higher resonances, we find that the
tensor meson can give a nontrivial contribution especially to the
decay process. When the contribution is
combined with the processes involving the vector and scalar meson intermediate
states, a good agreement with the recent measurements is achieved for both
decays. The effect of the is found to be sizable at the
intermediate photon energies and may be verified by precise measurements of the
recoil photon spectrum of the decay. The
dependence of the decay widths on various models for the - mixing
in the literature is also investigated.Comment: 16 pages, REVTeX, 6 figures, revised version, to appear in Phys. Rev.
Mass and Magnetic Moments of the Heavy Flavored Baryons with in Light Cone QCD Sum Rules
Inspired by the results of recent experimental discoveries for charm and
bottom baryons, the masses and magnetic moments of the heavy baryons with
containing a single heavy quark are studied within light cone QCD
sum rules method. Our results on the masses of heavy baryons are in good
agreement with predictions of other approaches, as well as with the existing
experimental values. Our predictions on the masses of the states, which are not
yet discovered in the experiments, can be tested in the future experiments. A
comparison of our results on the magnetic moments of these baryons and the
hyper central model predictions is presented.Comment: 33 Pages, 16 Figures and 3 Table
Light-Front Approach for Heavy Pentaquark Transitions
Assuming the two diquark structure for the pentaquark state as advocated in
the Jaffe-Wilczek model, there exist exotic parity-even anti-sextet and
parity-odd triplet heavy pentaquark baryons. The theoretical estimate of
charmed and bottom pentaquark masses is quite controversial and it is not clear
whether the ground-state heavy pentaquark lies above or below the strong-decay
threshold. We study the weak transitions of heavy pentaquark states using the
light-front quark model. In the heavy quark limit, heavy-to-heavy pentaquark
transition form factors can be expressed in terms of three Isgur-Wise
functions: two of them are found to be normalized to unity at zero recoil,
while the third one is equal to 1/2 at the maximum momentum transfer, in
accordance with the prediction of the large-Nc approach or the quark model.
Therefore, the light-front model calculations are consistent with the
requirement of heavy quark symmetry. Numerical results for form factors and
Isgur-Wise functions are presented. Decay rates of the weak decays Theta_b+ to
Theta_c0 pi+ (rho+), Theta_c0 to Theta+ pi- (rho-), Sigma'_{5b}+ to
Sigma'_{5c}0 pi+ (rho+) and Sigma'_{5c}0 to N_8+ pi- (rho-) with Theta_Q,
Sigma'_{5Q} and N_8 being the heavy anti-sextet, heavy triplet and light
octet pentaquarks, respectively, are obtained. For weakly decaying Theta_b+ and
Theta_c0, the branching ratios of Theta_b+ to Theta_c0 pi+, Theta_c0 to Theta+
pi- are estimated to be at the level of 10^{-3} and a few percents,
respectively.Comment: 33 pages, 3 figures, version to be published in Phys. Rev.
Light cone QCD sum rules study of the semileptonic heavy and transitions to and baryons
The semileptonic decays of heavy spin--1/2, and
baryons to the light spin-- 1/2, and baryons are investigated
in the framework of the light cone QCD sum rules. In particular, using the most
general form of the interpolating currents for the heavy baryons as well as the
distribution amplitudes of the and baryons, we calculate all
form factors entering the matrix elements of the corresponding effective
Hamiltonians in full QCD. Having calculated the responsible form factors, we
evaluate the decay rates and branching fractions of the related transitions.Comment: 30 Pages, 5 Figures and 18 Table
Light-Front Approach for Pentaquark Strong Decays
Assuming the two diquark structure for the pentaquark state as advocated in
the Jaffe-Wilczek model, we study the strong decays of light and heavy
parity-even pentaquark states using the light-front quark model in conjunction
with the spectator approximation. The narrowness of the Theta width is ascribed
to the p-wave configuration of the diquark pair. Taking the Theta width as a
benchmark, we estimate the rates of the strong decays Xi_{3/2}-- to Xi- pi-,
Sigma- K-, Sigma_{5c}0 to D_s- p, D_{s0}*- p and Xi_{5c}0 to D_s- Sigma+,
D_{s0}^{*-} Sigma+ with Sigma_{5c} Xi_{5c} being antisextet charmed pentaquarks
and D_{s0}* a scalar strange charmed meson. The ratio of Gamma(P_c to Baryon
D_{s0}*)/Gamma(P_c to Baryon D_s) is very useful for verifying the parity of
the antisextet charmed pentaquark P_c. It is expected to be of order unity for
an even parity P_c and much less than one for an odd parity pentaquark.Comment: 24 pages, 2 figure
Long-distant contribution and radiative decays to light vector meson
The discrepancy between the PQCD calculation and the CLEO data for
() stimulates our interest in
exploring extra mechanism of decay. In this work, we apply an
important non-perturbative QCD effect, i.e., hadronic loop mechanism, to study
radiative decay. Our numerical result shows that the
theoretical results including the hadronic loop contribution and the PQCD
calculation of are consistent with the corresponding
CLEO data of . We expect further experimental
measurement of at BES-III, which will be helpful to
test the hadronic loop effect on decay.Comment: 7 pages, 2 figures. Accepted for publication in Eur. Phys. J.
Magnetic Moments of Heavy Baryons Using Effective Mass and Screened Charge Scheme
Magnetic moments of heavy charmed baryons with are predicted
employing the concept of effective quark mass and screened charge of quark. We
also extend our scheme to predict the transition magnetic
moments. A comparison of our results with the predictions obtained in recent
models is presented.Comment: 19 pages, Accepted for publication in EPJ-
Department of Defense prostate cancer clinical trials consortium: A new instrument for prostate cancer clinical research
Background: In 2005, the US Department of Defense, through the US Army Medical Research and Materiel Command, Office of the Congressionally Directed Medical Research Programs, created a funding mechanism to form a clinical trials consortium to conduct phase I and II studies in prostate cancer. This is the first report of the Prostate Cancer Clinical Trials Consortium (PCCTC). Patients and Methods: The Department of Defense award supports a consortium of 10 prostate cancer research centers. Memorial Sloan-Kettering Cancer Center was awarded the Coordinating Center grant for the consortium and charged with creating an infrastructure to conduct early-phase multicenter clinical trials. Each participating center was required to introduce ≥ 1 clinical trial per year and maintain accrual of a minimum of 35 patients per year. Results: The PCCTC was launched in 2006 and now encompasses 10 leading prostate cancer research centers. Fifty-one trials have been opened, and 1386 patients have been accrued at member sites. Members share an online clinical trial management system for protocol tracking, electronic data capture, and data storage. A legal framework has been instituted, and standard operating procedures, an administrative structure, editorial support, centralized budgeting, and mechanisms for scientific review are established. Conclusion: The PCCTC fulfills a congressional directive to create a clinical trials instrument dedicated to early-phase prostate cancer studies. The member institutions have built an administrative, informatics, legal, financial, statistical, and scientific infrastructure to support this endeavor. Clinical trials are open and accruing in excess of federally mandated goals
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