arXiv subjects

Bruno El-Bennich

Publications and source records attributed to Bruno El-Bennich.

42 records · Page 3Linked to original sources

arXiv2011

Flavor SU(4) breaking between effective couplings

Using a framework in which all elements are constrained by Dyson-Schwinger equation studies in QCD, and therefore incorporates a consistent, direct and simultaneous description of light- and heavy-quarks and the states they constitute, we analyze the accuracy of SU(4)-flavor symmetry relations between πρπ, KρK and DρD couplings. Such relations are widely used in phenomenological analyses of the interactions between matter and charmed mesons. We find that whilst SU(3)-flavor symmetry is accurate to 20%, SU(4) relations underestimate the DρD coupling by a factor of five.

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arXiv2010

Strong D* -> D+pi and B* -> B+pi couplings

We compute g_{D* D pi} and g_{B* B pi} using a framework in which all elements are constrained by Dyson-Schwinger equation studies of QCD, and therefore incorporates a consistent, direct and simultaneous description of light- and heavy-quarks and the states they may constitute. We link these couplings with the heavy-light-meson leptonic decay constants, and thereby obtain g_{D* D pi}=15.9+2.1/-1.0 and g_{B* B pi}=30.0+3.2/-1.4. From the latter we infer \hat-g_B=0.37+0.04/-0.02. A comparison between g_{D* D pi} and g_{B* B pi} indicates that when the c-quark is a system's heaviest constituent, Lambda_{QCD}/m_c-corrections are not under good control.

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arXiv2009

Exploring the light-quark interaction

Two basic motivations for an upgraded JLab facility are the needs: to determine the essential nature of light-quark confinement and dynamical chiral symmetry breaking (DCSB); and to understand nucleon structure and spectroscopy in terms of QCD's elementary degrees of freedom. During the next ten years a programme of experiment and theory will be conducted that can address these questions. We present a Dyson-Schwinger equation perspective on this effort with numerous illustrations, amongst them: an interpretation of string-breaking; a symmetry-preserving truncation for mesons; the nucleon's strangeness sigma-term; and the neutron's charge distribution.

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arXiv2007

The Ground Scalar Nonet and D Decays

A short review on light scalar mesons is performed both in experiment and theory. A naive model, constrained by D branching ratios, is derived in order to make predictions on the wave functions of the $f_0(600)$ and $a_0(980)$ mesons. This leads us to compute transition form factors between the pseudoscalar $B$ and scalar mesons.

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arXiv2003

Annihilation range and final-state interaction in the antiproton-proton annihilation into pi-pi+

The large set of accurate data on differential cross section and analyzing power from the CERN LEAR experiment on $\bar pp \to π^+π^-$ in the range from 360 to 1550 MeV/c is well reproduced within a distorted wave approximation approach. The initial $\bar pp$ scattering wave functions originate from a recent $\bar N N$ model. The transition operator is obtained from a combination of the $^3P_0$ and $^3S_1$ quark-antiquark annihilation mechanisms. A good fit to the data, in particular the reproduction of the double dip structure observed in the analyzing powers, requires quark wave functions for proton, antiproton, and pions with radii slightly larger than the respective measured charge radii. This corresponds to an increase in range of the annihilation mechanisms and consequently the amplitudes for total angular momentum J=2 and higher are much larger than in previous approaches. The final state $ππ$ wave functions, parameterized in terms of $ππ$ phase shifts and inelasticities, are also a very important ingredient for the fine tuning of the fit to the observables.

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arXiv2003

The reaction antirproton-proton into pi+pi-: relativistic aspects and final-state interaction in the pion wave functions

We use a distorted wave approximation approach which includes $^3P_0$ and $^3S_1$ quark-antiquark annihilation mechanisms to reproduce the data set from LEAR on $\bar p p\to π^+π^-$ in the range from 360 to 1550 MeV/c. Improvements of the model are sought by implementing final-state interactions of the pions and by observing that the annihilation is too short-ranged in earlier attempts to describe the data. While the former improvement is due to to the final-state $ππ$ wave functions solely, the latter one originates from quark wave functions for proton, antiproton, and pions with radii slightly larger than the respective measured charge radii. This increase in hadron radius, as compared with typically much smaller radii used before in the quark model, increases the annihilation range and thereby the amplitudes for $J\ge2$ are much higher. Finally, given the very high kinetic energy of the final pions, we investigate the role of relativistic corrections in the pion wave functions when boosted into the center-of-mass frame.

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