1,668 research outputs found

    The Vector and Axial-Vector Charmonium-like States

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    After constructing all the tetraquark interpolating currents with JPC=1+,1,1++J^{PC}=1^{-+}, 1^{--}, 1^{++} and 1+1^{+-} in a systematic way, we investigate the two-point correlation functions to extract the masses of the charmonium-like states with QCD sum rule. For the 11^{--} qcqˉcˉqc\bar q\bar c charmonium-like state, mX=4.64.7m_X=4.6\sim4.7 GeV, which implies a possible tetraquark interpretation for the state Y(4660). The masses for both the 1++1^{++} qcqˉcˉqc\bar q\bar c and scsˉcˉsc\bar s\bar c charmonium-like states are around 4.04.24.0\sim 4.2 GeV, which are slightly above the mass of X(3872). For the 1+1^{-+} qcqˉcˉqc\bar q\bar c charmonium-like state, the extracted mass is 4.54.74.5\sim 4.7 GeV. We also discuss the possible decay modes and experimental search of the 1+1^{-+} charmonium-like states.Comment: 18 pages, 6 figures and 6 table

    Radiative Leptonic BcB_c Decays

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    We analyze the radiative leptonic BcB_c decay mode: BcνγB_c \to \ell \nu \gamma (=e,μ\ell=e, \mu) using a QCD-inspired constituent quark model. The prediction: B(Bcνγ)3×105{\cal B}(B_c \to \ell \nu \gamma)\simeq 3 \times 10^{-5} makes this channel experimentally promising in view of the large number of BcB_c mesons which are expected to be produced at the future hadron facilities.Comment: LaTex, 12 pages, 2 figures. A discussion on gauge invariance added. Numerical results update

    J/psi couplings to charmed resonances and to pi

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    We present an evaluation of the strong couplings JD^(*)D^(*) and JD^(*)D^(*)pi by an effective field theory of quarks and mesons. These couplings are necessary to calculate pi+J/psi --> D^(*)+barD^(*) cross sections, an important background to the J/psi suppression signal in the quark-gluon plasma. We write down the general effective lagrangian and compute the relevant couplings in the soft pion limit and beyond.Comment: 11 pages, 4 figures, 2 reference added and minor comments, style changed to RevTe

    Heavy-to-light form factors: sum rules on the light cone and beyond

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    We report the first systematic analysis of the off-light-cone effects in sum rules for heavy-to-light form factors. These effects are investigated in a model based on scalar constituents, which allows a technically rather simple analysis but has the essential features of the analogous QCD calculation. The correlator relevant for the extraction of the heavy-to-light form factor is calculated in two different ways: first, by adopting the full Bethe-Salpeter amplitude of the light meson and, second, by performing the expansion of this amplitude near the light cone x2=0x^2=0. We demonstrate that the contributions to the correlator from the light-cone term x2=0x^2=0 and the off-light-cone terms x20x^2\ne 0 have the same order in the 1/mQ1/m_Q expansion. The light-cone correlator, corresponding to x2=0x^2=0, is shown to systematically overestimate the full correlator, the difference being ΛQCD/δ\sim \Lambda_{\rm QCD}/\delta, with δ\delta the continuum subtraction parameter of order 1 GeV. Numerically, this difference is found to be 10-20%.Comment: revtex 14 pages, version to be published in Phys. Rev. D (discussion in Sect. 3 extended, example in Sect. 4 added

    Semileptonic B decays into excited charmed mesons from QCD sum rules

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    Exclusive semileptonic BB decays into excited charmed mesons are studied with QCD sum rules in the leading order of heavy quark effective theory. Two universal Isgur-Wise functions \tau and \zeta for semileptonic B decays into four lowest lying excited DD mesons (D1D_1, D2D_2^*, D0D'_0, and D1D'_1) are determined. The decay rates and branching ratios for these processes are calculated.Comment: RevTeX, 17 pages including 2 figure

    \u3cem\u3eKiobel\u3c/em\u3e Amici Curiae Brief of Law of Nations Scholars

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    The question presented is “whether and under what circumstances the Alien Tort Statute, 28 U.S.C. § 1350, allows courts to recognize a cause of action for violations of the law of nations occurring within the territory of a sovereign other than the United States.” In this Amicus Brief we argue from a historical perspective going back to the Middle Ages that when the law of nations is in issue, not only is there no presumption against extraterritoriality, but jurisdiction over causes of action arising abroad is in many cases required. More specifically, we argue that Congress affirmatively conferred universal jurisdiction in the Alien Tort Statute [“ATS”] under the law of nations, and that to refuse such jurisdiction in cases of denial of justice would be contrary to longstanding principles of the law of nations. In short, limiting the ATS to claims arising in U.S. territory would contravene both the statute’s clear indication of universal jurisdiction and the Charming Betsy canon of construction that statutes should not be construed to violate the law of nations

    Remarks on the hadronic matrix elements relevant to the SUSY K-Kbar mixing amplitude

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    We compute the 1-loop chiral corrections to the bag parameters which are needed for the discussion of the SUSY K-Kbar mixing problem in both finite and infinite volume. We then show how the bag parameters can be combined among themselves and with some auxiliary quantities and thus sensibly reduce the systematic errors due to chiral extrapolations as well as those due to finite volume artefacts present in the results obtained from lattice QCD. We also show that in some cases these advantages remain as such even after including the 2-loop chiral corrections. Similar discussion is also made for the K --> pi electro-weak penguin operators.Comment: 13 pages, 3 figures [added 1 reference and a discussion about the impact of the NNLO chiral corrections to the "golden ratios" (c.f. Sec.6)

    The electromagnetic effects in Ke4K_{e4} decay

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    The final state interaction of pions in Ke4K_{e4} decay allows one to obtain the value of the isospin and angular momentum zero ππ\pi\pi scattering length a00a_0^0.We take into account the electromagnetic interaction of pions and isospin symmetry breaking effects caused by different masses of neutral and charged pions and estimate the impact of these effects on the procedure of scattering length extraction from Ke4K_{e4} decay.Comment: 8 pages,1 figur

    In-medium hadronic spectral functions through the soft-wall holographic model of QCD

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    We study the scalar glueball and vector meson spectral functions in a hot and dense medium by means of the soft-wall holographic model of QCD. Finite temperature and density effects are implemented through the AdS/RN metric. We analyse the behaviour of the hadron masses and widths in the (T,μ)(T,\mu) plane, and compare our results with the experimental ones and with other theoretical determinations.Comment: 16 pages, 6 figures. matching the published versio
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