%0 Journal Article
%T Can the X(3872) be a 1$^{++}$ four-quark state?
%+ Laboratoire de Physique Théorique et Astroparticules (LPTA)
%+ Laboratoire de Physique Subatomique et de Cosmologie (LPSC)
%A Matheus, R.D.
%A Narison, S.
%A Nielsen, M.
%A Richard, J.-M.
%Z 14 pages, 9 figures
%< avec comité de lecture
%Z LPSC 0663
%@ 1550-7998
%J Physical Review D
%I American Physical Society
%V 75
%P 014005
%8 2007
%D 2007
%Z hep-ph/0608297
%R 10.1103/PhysRevD.75.014005
%Z 11.55.Hx, 12.38.Lg, 12.39.-x
%Z Physics [physics]/High Energy Physics - Phenomenology [hep-ph]Journal articles
%X We use QCD spectral sum rules to test the nature of the meson X(3872), assumed to be an exotic four-quark (c\bar{c}q\bar{q}) state with J^{PC}=1^{++}. For definiteness, we work with the current proposed recently by Maiani et al [1], at leading order in \alpha_s, consider the contributions of higher dimension condensates and keep terms which are linear in the light quark mass m_q. We find M_X=(3925+- 127) MeV which is compatible, within the errors, with he experimental candidate X(3872), while the SU(3) breaking-terms lead to an unusual mass-splitting M_{X^{s}}-M_X=- (61+-30) MeV. The mass-difference between the neutral states due to isospin violation of about 2 MeV is much smaller than the value 8 MeV proposed in [1]. For the b-quark, we predict M_{X_b}= (10144+-106) MeV for the X_b(b\bar{b}q \bar{q}), which is much below the {\bar B}B* threshold in contrast to the {\bar B}B* molecule prediction [2], and for the X_b^s(b\bar{b}s \bar{s}), a mass-splitting M_{X^s_{b}}-M_{X_b}=-(121+-182) MeV. Our analysis also indicates that the mass-splitting between the ground state and the radial excitation of about (225~250) MeV is much smaller than in the case of ordinary mesons and is (within the errors) flavour-independent. We also extract the decay constants, analogous to f_\pi, of such mesons, which are useful for further studies of their leptonic and hadronic decay widths. The uncertainties of our estimates are mainly due to the ones from the c and b quark masses.
%G English
%L in2p3-00090207
%U https://hal.in2p3.fr/in2p3-00090207
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%~ UGA
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