Search results for "strong interaction"
showing 10 items of 77 documents
Experimental Evidence for an Attractive p-φ Interaction
2021
Physical review letters 127(17), 172301 (2021). doi:10.1103/PhysRevLett.127.172301
Photon-pion charge asymmetry in e+e− reactions: A laboratory for perturbative QCD phases
1987
Abstract The charge asymmetry in the production of a photon and a meson in e + e - annihilation is studied in perturbative QCD. This quantity measures the interference of amplitudes governed by different momentum scales. It is thus a powerful tool to probe strong interaction phases at high energy and in the context of Sudakov exponentiation and the chromo Coulomb phase. We find a null result at the lowest non-trivial order off α s in the entire kinematic region described by perturbative QCD.
Lattice QCD and the anomalous magnetic moment of the muon
2019
The anomalous magnetic moment of the muon, a_mu, has been measured with an overall precision of 540 ppb by the E821 experiment at BNL. Since the publication of this result in 2004 there has been a persistent tension of 3.5 standard deviations with the theoretical prediction of a_mu based on the Standard Model. The uncertainty of the latter is dominated by the effects of the strong interaction, notably the hadronic vacuum polarisation (HVP) and the hadronic light-by-light (HLbL) scattering contributions, which are commonly evaluated using a data-driven approach and hadronic models, respectively. Given that the discrepancy between theory and experiment is currently one of the most intriguing …
Strong-interaction Isospin-symmetry Breaking Within the Density Functional Theory
2015
The conventional Skyrme interaction is generalized by adding zero-range charge-symmetry-breaking and charge-independence-breaking terms, and the corresponding energy density functional is derived. It is shown that the extended model accounts for experimental values of mirror and triplet displacement energies (MDEs and TDEs) in sd-shell isospin triplets with, on average, about 100~keV precision using only two additional adjustable coupling constants. Moreover, the model is able to reproduce, for the first time, the A=4n versus A=4n+2 staggering of the TDEs.
Initial-final state strong interaction corrections to the B¯→Dv¯ℓ (v¯ττ) decays
2020
Deeply bound levels in kaonic atoms
2000
Using a microscopic antikaon-nucleus optical potential recently developed by Ramos and Oset (nucl-th/9906016, in print in Nuclear Physics A) from a chiral model, we calculate strong interaction shifts and widths for $K^-$ atoms. This purely theoretical potential gives an acceptable description of the measured data ($\chi^2/{\rm num.data}= 3.8$), though it turns out to be less attractive than what can be inferred from the existing kaon atomic data. We also use a modified potential, obtained by adding to the latter theoretical one a s-wave term which is fitted to known experimental kaonic data ($\chi^2/{\rm degree of freedom}= 1.6$), to predict deeply bound $K^-$ atomic levels, not detected y…
Use of a running coupling in the NLO calculation of forward hadron production
2018
We address and solve a puzzle raised by a recent calculation [1] of the cross-section for particle production in proton-nucleus collisions to next-to-leading order: the numerical results show an un- reasonably large dependence upon the choice of a prescription for the QCD running coupling, which spoils the predictive power of the calculation. Specifically, the results obtained with a prescription formulated in the transverse coordinate space differ by one to two orders of magnitude from those obtained with a prescription in momentum space. We show that this discrepancy is an artefact of the interplay between the asymptotic freedom of QCD and the Fourier transform from coordinate space to mo…
Maximal isospin few-body systems of nucleons and $\Xi$ hyperons
2016
By using local central Yukawa-type interactions that reproduce the low-energy parameters of the latest updates of the Nijmegen ESC08c potentials we show that the $N\Xi$, $NN\Xi$, $N\Xi\Xi$ and $NN\Xi\Xi$ systems with maximal isospin are bound. Since in these states the strong decay $N\Xi\to\Lambda\Lambda$ is forbidden by isospin conservation, these strange few-body systems will be stable under the strong interaction. These results may suggest that other states with different number of $N$'s and $\Xi$'s in the maximal isospin channel could also be bound.
ββ2νdecay in48Ca
2001
A schematic study of the $\ensuremath{\beta}\ensuremath{\beta}2\ensuremath{\nu}$ decay of ${}^{48}\mathrm{Ca}$ is made in a shell-model approach. The emphasis is especially put on the role of the spin-orbit potential in relation with the contribution of other terms in the strong interaction. This is discussed with a particular attention to the behavior of these ones under the SU(4) symmetry. Different methods in calculating the transition amplitude are also looked at with the aim to determine their reliability and, eventually, why they do not work. Further aspects relative to the failure of the operator expansion method to reproduce the results of more elaborate calculations are examined.
Photon emission in neutral-current interactions at intermediate energies
2013
Neutral current photon emission reactions with nucleons and nuclei are studied. These processes are important backgrounds for nu_mu to nu_e (bar(nu)_mu to bar(nu)_e) appearance oscillation experiments where electromagnetic showers instigated by electrons (positrons) and photons are not distinguishable. At intermediate energies, these reactions are dominated by the weak excitation of the Delta(1232) resonance and its subsequent decay into Ngamma There are also non-resonant contributions that, close to threshold, are fully determined by the effective chiral Lagrangian of strong interactions. In addition, we have also included mechanisms mediated by nucleon excitations (N*) from the second res…