879 research outputs found

    Study of Bs-> \phi l^+ l^-$ Decay in a Single Universal Extra Dimension

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    Utilizing form factors calculated within the light-cone sum rules, we have evaluated the decay branching ratios of BsϕγB_s\to \phi\gamma and Bsϕ+B_s\to \phi \ell^+\ell^- 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 Bsϕ+B_s \to \phi \ell^+\ell^-, 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 1/R=1000GeV1/R = 1000 \mathrm{GeV}, two models have approximately the same predictions. Compared with data from CDF of Bsϕμ+μB_s \to \phi \mu^+ \mu^-, the 1/R tends to be larger than 350GeV350 \mathrm{GeV}. 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 NcN_c Limit

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    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 Qˉsuud\bar Qsuud and Qˉsudd\bar Qsudd states discussed by Lipkin, and a a previously unstudied Qˉssud\bar Qssud state. These states will have JP=12+J^P={1\over2}^+ 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 ρπ0π0γ\rho \to \pi^0 \pi^0 \gamma and ωπ0π0γ\omega \to \pi^0 \pi^0 \gamma

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    The role of higher meson resonances with spin 1 and 2 is investigated quantitatively in the decay processes of ρπ0π0γ\rho \to \pi^0\pi^0 \gamma and ωπ0π0γ\omega \to \pi^0 \pi^0 \gamma. Among the higher resonances, we find that the f2(1270)f_2(1270) tensor meson can give a nontrivial contribution especially to the ωπ0π0γ\omega \to \pi^0 \pi^0 \gamma decay process. When the f2f_2 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 f2(1270)f_2(1270) is found to be sizable at the intermediate photon energies and may be verified by precise measurements of the recoil photon spectrum of the ωπ0π0γ\omega \to \pi^0 \pi^0 \gamma decay. The dependence of the decay widths on various models for the ρ\rho-ω\omega 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 J=3/2J=3/2 in Light Cone QCD Sum Rules

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    Inspired by the results of recent experimental discoveries for charm and bottom baryons, the masses and magnetic moments of the heavy baryons with JP=3/2+J^P=3/2^+ 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

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    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 ΞQ\Xi_{Q} and ΞQ\Xi'_{Q} transitions to Ξ\Xi and Σ\Sigma baryons

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    The semileptonic decays of heavy spin--1/2, Ξb(c)\Xi_{b(c)} and Ξb(c)\Xi'_{b(c)} baryons to the light spin-- 1/2, Ξ\Xi and Σ\Sigma 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 Ξ\Xi and Σ\Sigma 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

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    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 χc1\chi_{c1} radiative decays to light vector meson

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    The discrepancy between the PQCD calculation and the CLEO data for χc1γV\chi_{c1}\to \gamma V (V=ρ0,ω,ϕV=\rho^0,\,\omega,\,\phi) stimulates our interest in exploring extra mechanism of χc1\chi_{c1} decay. In this work, we apply an important non-perturbative QCD effect, i.e., hadronic loop mechanism, to study χc1γV\chi_{c1}\to \gamma V radiative decay. Our numerical result shows that the theoretical results including the hadronic loop contribution and the PQCD calculation of χc1γV\chi_{c1}\to \gamma V are consistent with the corresponding CLEO data of χc1γV\chi_{c1}\to \gamma V. We expect further experimental measurement of χc1γV\chi_{c1}\to \gamma V at BES-III, which will be helpful to test the hadronic loop effect on χc1\chi_{c1} decay.Comment: 7 pages, 2 figures. Accepted for publication in Eur. Phys. J.

    Magnetic Moments of JP=3/2+J^P=3/2^+ Heavy Baryons Using Effective Mass and Screened Charge Scheme

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    Magnetic moments of heavy charmed baryons with JP=3/2+J^P=3/2^+ are predicted employing the concept of effective quark mass and screened charge of quark. We also extend our scheme to predict the 3/2+>1/2+3/2^+ --> 1/2^+ 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

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    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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