Journal ArticleDOI

# Heavy meson hyperfine splitting: A Complete 1/m(Q) calculation

N. Di Bartolomeo
23 Mar 1995-Physics Letters B (North-Holland)-Vol. 347, Iss: 3, pp 405-412

AbstractThe hyperfine splittings Δ d = (m d s ∗ − m nd s ) − (m d ∗+ − m d + ) and Δ d = (m b s ∗ − m b s ) − (m b ∗0 − m b 0 ) are analyzed in the framework of an effective lagrangian possessing chiral, heavy flavour and spin symmetries, explicitly broken by a complete set of first order terms. Among these terms, those responsible for the difference between the couplings gp ∗ p ∗ π and gp ∗ p π are evaluated in the QCD sum rules approach. Their contribution to Δd and to Δb appears to quantitatively balance previously estimated chiral effects, in nice agreement with the experimental data, solving a suspected puzzle for heavy quark theory.

Topics: QCD sum rules (50%)

Content maybe subject to copyright    Report

##### Citations
More filters

Journal ArticleDOI

Abstract: The approximate symmetries of Quantum ChromoDynamics in the infinite heavy quark (Q = c, b) mass limit (mQ → ∞) and in the chiral limit for the light quarks (mq → 0, q = u, d, s) can be used together to build up an effective chiral lagrangian for heavy and light mesons describing strong interactions among effective meson fields as well as their couplings to electromagnetic and weak currents, including the relevant symmetry-breaking terms. The effective theory includes heavy ( Q q ) mesons of both negative and positive parity, light pseudoscalars, as well as light vector mesons. We summarize the estimates for the parameters entering the effective lagrangian and discuss in particular some phenomenologically important couplings, such as g B ∗ Bπ . The hyperfine splitting of heavy mesons is discussed in detail. The effective lagrangian allows for the possibility to describe consistently weak couplings of heavy (B, D) to light ( π, ϱ, K ∗ , etc. ) mesons. The method has however its own limitations, due to the requirement that the light meson momenta should be small, and we discuss how such limitations can be circumvented through reasonable ansatz on the form factors. Flavour conserving ( e.g. B ∗ → Bγ ) and flavour changing ( e.g. B → K ∗ γ ) radiative decays provide another field of applications of effective lagrangians; they are discussed together with their phenomenological implications. Finally, we analyze effective lagrangians describing heavy charmonium- like (QQ) mesons and their strong and electromagnetic interactions. The role of approximate heavy quark symmetries for this case and the phenomenological tests of these models are also discussed.

446 citations

Journal ArticleDOI
01 May 2003
Abstract: Precise knowledge onB meson decay properties plays an essential role in testing the unitarity of the CKM matrix [1,2]. The experimental status relevant to the unitarity test is now promising because experimental uncertainties are already very small or expected to be reduced well in the near future [3]. On the other hand, theoretical calculations relevant to the test are still not sufficiently accurate due to the non-perturbative effect of QCD. Lattice QCD is an ideal tool to deal with this effect and should be able to reduce the current theoretical uncertainties [4]. Apart from the asymmetric ee colliders, there are two important upcoming experiments for the unitarity test. The Tevatron Run II will produce a large number of and variety of b and chadrons, and their basic properties such as mass and lifetime will be precisely measured [5]. What is important for us is that once B s -B 0 s mixing is observed the mass difference ∆MBs will be measured with a few percent accuracy. The width difference in the Bs meson system is also expected to be measured precisely. Another exciting experiment is the CLEO-c project [6]. There, charmed quarkonia, hybrid states and glueballs will be observed. In particular the leptonic and the semileptonic decays of D mesons are expected to be measured with a few percent level. Advancing lattice QCD calculations with a view to combining them with these precise experimental results is an urgent task in front of us. In this review, I will focus on new and updated calculations of hadron matrix elements. The current status and progress made in spectrum calculations and formulations are not covered, although they are very important and interesting. In particular, I will mainly discuss the lattice determination of the B-B mixing amplitude and how to put a strong constraint on the poorly known CKM element |Vtd|. The other important quantities such as form factors of semi-leptonic decays will be mentioned briefly. Recently several suggestions to improve the limits on accuracy of present lattice calculations have been made in methodology. I will briefly introduce some of them before summarizing my point of view on the current status.

19 citations

Journal ArticleDOI
, Wei Liu1
Abstract: The strong interactions of the negative-parity heavy mesons with ρ meson may be described consistently in the context of an effective Lagrangian, which is invariant under isospin SU ( 2 ) transformation. Four coupling constants g H H ρ , f H ∗ H ρ , g H ∗ H ∗ ρ and f H ∗ H ∗ ρ enter the effective Lagrangian, where H ( H ∗ ) denotes a pseudoscalar bottom or charm meson (the corresponding vector meson). Using QCD light cone sum rule (LCSR) method and, as inputs, the hadronic parameters updated recently, we give an estimate of g H ∗ H ∗ ρ and f H ∗ H ∗ ρ , about which little was known before, and present an improved result for g H H ρ and f H ∗ H ρ . Also, we examine the heavy quark asymptotic behavior of these nonperturbative quantities and assess the two low energy parameters β and λ of the corresponding effective chiral Lagrangian.

11 citations

Journal ArticleDOI
Abstract: We report on a first next-to-next-to-leading order calculat ion of the decay constants of the D (D ∗ ) and B (B ∗ ) mesons using a covariant formulation of chiral perturbati on theory. It is shown that, using the state-of-the-art lattice QCD results on fDs /fD as input, one can predict quantitatively the ratios of fD � s /fD �, fBs/fB, and fB � s /fB � taking into account heavy-quark spin-flavor symmetry break ing effects on the relevant low-energy constants. The predicted relation s between these ratios, fD� /fD� fDs /fD, and their light-quark mass dependence should be testable in future lattice QCD simulations, providing a stringent test of our understanding of he avy quark spin-flavor symmetry, chiral symmetry and their breaking patterns.

7 citations

Journal ArticleDOI
Abstract: The couplings of pions with heavy baryons g(2)(Sigma*,Sigma) and g(3)(Sigma*,Lambda) are studied with light-cone QCD sum rules in the leading order of heavy quark effective theory. Both sum rules are stable. Our results are g(2)= 1.56+/-0.3 +/-0.3, g(3) = 0.94 +/- 0.06 +/- 0.2. (C) 1998 Elsevier Science B.V. All rights reserved.

6 citations

##### References
More filters

Journal ArticleDOI
TL;DR: This biennial Review summarizes much of Particle Physics using data from previous editions, plus 2205 new measurements from 667 papers, and features expanded coverage of CP violation in B mesons and of neutrino oscillations.
Abstract: This biennial Review summarizes much of Particle Physics. Using data from previous editions, plus 2205 new measurements from 667 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. This edition features expanded coverage of CP violation in B mesons and of neutrino oscillations. For the first time we cover searches for evidence of extra dimensions (both in the particle listings and in a new review). Another new review is on Grand Unified Theories. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov.

5,118 citations

Journal ArticleDOI

TL;DR: The flavor and spin symmetry of the heavy quarks and the spontaneously broken approximate SU(3){sub {ital L}}{times} SU( 3){ sub {ital R}} chiral symmetry ofThe light quarks are exploited to formulate a theory describing the low-energy interactions of theheavy mesons and heavy baryons with the Goldstone bosons.
Abstract: The flavor and spin symmetry of the heavy quarks and the spontaneously broken approximate ${\mathrm{SU}(3)}_{L}\ifmmode\times\else\texttimes\fi{}{\mathrm{SU}(3)}_{R}$ chiral symmetry of the light quarks are exploited to formulate a theory describing the low-energy interactions of the heavy mesons ($Q\overline{q}$ bound states) and heavy baryons (${\mathrm{Qq}}_{1}{q}_{2}$ bound states) with the Goldstone bosons $\ensuremath{\pi}$, $K$, and $\ensuremath{\eta}$. The theory contains only three parameters independent of the number of heavy-quark species involved. They can be determined by the decays ${D}^{*}\ensuremath{\rightarrow}D+\ensuremath{\pi}$, ${\ensuremath{\Sigma}}_{c}\ensuremath{\rightarrow}{\ensuremath{\Lambda}}_{c}+\ensuremath{\pi}$, and ${\ensuremath{\Sigma}}_{c}^{*}\ensuremath{\rightarrow}{\ensuremath{\Sigma}}_{c}+\ensuremath{\pi}$. Theoretically, these coupling constants are related, through partial conservation of axial-vector current, to the axial charges of the heavy mesons and the heavy baryons. They are all calculable in the nonrelativistic quark model by using the spin wave functions of these particles alone. The theory is applied to strong decays and semileptonic weak decays of the heavy mesons and baryons. The implications are also discussed.

403 citations

Journal ArticleDOI
Abstract: We describe the chiral symmetric couplings of pions to heavy mesons (B or D), valid in the portion of phase space where the pions have low momentum. In order to include consistently all low energy excitations, the vector mesons (B ∗ or D ∗ ) must appear explicitly in the effective lagrangian. The result is then invariant under both the chiral and heavy quark symmetries. We include matrix elements relevant for various weak decays.

377 citations

Journal ArticleDOI
V.A. Novikov
Abstract: The purpose of this paper is twofold. First, we are prompted by some recent publications to reply to the criticism of the QCD sum-rules approach contained therein. Hopefully, some of the discussion is of wider interest. In particular, we point out that the multi-gluon operators unlike the multi-quark ones, relevant to the sum rules, do not factorize at large N c . This implies that the masterfield, even if it is found, will be of no immediate help in evaluating the quarkonium spectrum. Second, we derive new sum rules for light quarks which are sensitive to the mean intensity of the gluon field in the vacuum (the so-called gluon condensate, or 〈vac| G 2 |vac〉). New sum rules confirm the standard value of 〈vac| G 2 |vac〉. Some casual remarks on the π 0 transitions into two virtual photons, π 0 → γ * γ * , are also presented. Finally, we enumerate (in sect. 7) basic points of the sum-rule approach and discuss, im brief, the unsolved problems.

215 citations

Journal ArticleDOI

Abstract: We introduce an effective lagrangian including negative and positive parity heavy mesons containing a heavy quark, light pseudoscalars, and light vector resonances, with their allowed interactions, using heavy quark spin-flavour symmetry, chiral symmetry, and the hidden symmetry approach for light vector resonances. On the basis of such a lagrangian, by considering the allowed weak currents and by including the contributions from the nearest unitarity poles we calculate the form factors for semileptonic decays of B and D mesons into light pseudoscalars and light vector resonances. The available data, together with some additional assumptions, allow for a set of predictions in the different semileptonic channels, which can be compared with those following from different approaches. A discussion of non-dominant terms in our approach, which attempts at including a rather complete dynamics, will however have to wait till more abundant data become available.

109 citations