The Experts below are selected from a list of 38106 Experts worldwide ranked by ideXlab platform
Andrzej J Buras - One of the best experts on this subject based on the ideXlab platform.
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leptoquarks meet e e and rare Kaon processes
Journal of High Energy Physics, 2018Co-Authors: Christoph Bobeth, Andrzej J BurasAbstract:We analyse for the first time the CP violating ratio e′/e in K → ππ decays in leptoquark (LQ) models. Assuming a mass gap to the electroweak (EW) scale, the main mechanism for LQs to contribute to e′/e is EW gauge-mixing of semi-leptonic into non-leptonic operators, which we treat in the Standard Model effective theory (SMEFT). We perform also the one-loop decoupling for scalar LQs, finding that in all models with both left-handed and right-handed LQ couplings box-diagrams generate numerically strongly enhanced EW-penguin operators Q8,8′ already at the LQ scale. We then investigate correlations of e′/e with rare Kaon processes ( $$ {K}_L\to {\pi}^0\nu \overline{\nu} $$ , $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ , $$ {K}_L\to {\pi}^0\ell \overline{\ell} $$ , $$ {K}_S\to \mu \overline{\mu} $$ , ΔM K and e K ) and find that even imposing only a moderate enhancement of (e′/e)NP = 5 × 10−4 to explain the current anomaly hinted by the Dual QCD approach and RBC-UKQCD lattice QCD calculations leads to conflicts with experimental upper bounds on rare Kaon processes. They exclude all LQ models with only a single coupling as an explanation of the e′/e anomaly and put strong-to-serious constraints on parameter spaces of the remaining models. Future results on $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ from the NA62 collaboration, $$ {K}_L\to {\pi}^0\nu \overline{\nu} $$ from the KOTO experiment and $$ {K}_S\to \mu \overline{\mu} $$ from LHCb will even stronger exhibit the difficulty of LQ models in explaining the measured e′/e, in case the e′/e anomaly will be confirmed by improved lattice QCD calculations. Hopefully also improved measurements of $$ {K}_L\to {\pi}^0\ell \overline{\ell} $$ decays will one day help in this context.
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leptoquarks meet varepsilon varepsilon and rare Kaon processes
arXiv: High Energy Physics - Phenomenology, 2017Co-Authors: Christoph Bobeth, Andrzej J BurasAbstract:We analyse for the first time the CP violating ratio $\varepsilon'/\varepsilon$ in $K\to \pi\pi$ decays in leptoquark (LQ) models. Assuming a mass gap to the electroweak (EW) scale, the main mechanism for LQs to contribute to $\varepsilon'/\varepsilon$ is EW gauge-mixing of semi-leptonic into non-leptonic operators, which we treat in the Standard Model effective theory (SMEFT). We perform also the one-loop decoupling for scalar LQs, finding that in all models with both left-handed and right-handed LQ couplings box-diagrams generate numerically strongly enhanced EW-penguin operators $Q_{8,8'}$ already at the LQ scale. We then investigate correlations of $\varepsilon'/\varepsilon$ with rare Kaon processes ($K_L\to\pi^0\nu\bar\nu$, $K^+\to\pi^+\nu\bar\nu$, $K_L\to\pi^0\ell\bar\ell$, $K_S\to\mu\bar\mu$, $\Delta M_K$ and $\varepsilon_K$) and find that even imposing only a moderate enhancement of $(\varepsilon'/\varepsilon)_{\rm NP} = 5 \times 10^{-4}$ to explain the current anomaly hinted by the Dual QCD approach and RBC-UKQCD lattice QCD calculations leads to conflicts with experimental upper bounds on rare Kaon processes. They exclude all LQ models with only a single coupling as an explanation of the $\varepsilon'/\varepsilon$ anomaly and put strong-to-serious constraints on parameter spaces of the remaining models. Future results on $K^+\to\pi^+\nu\bar\nu$ from the NA62 collaboration, $K_L\to\pi^0\nu\bar\nu$ from the KOTO experiment and $K_S\to\mu\bar\mu$ from LHCb will even stronger exhibit the difficulty of LQ models in explaining the measured $\varepsilon'/\varepsilon$, in case the $\varepsilon'/\varepsilon$ anomaly will be confirmed by improved lattice QCD calculations. Hopefully also improved measurements of $K_L\to\pi^0\ell\bar\ell$ decays will one day help in this context.
William Detmold - One of the best experts on this subject based on the ideXlab platform.
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baryon masses at nonzero isospin Kaon density
Physical Review Letters, 2013Co-Authors: William Detmold, Amy NicholsonAbstract:United States. Dept. of Energy. Outstanding Junior Investigator Program (Award DE-SC000-1784)
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baryon masses at nonzero isospin Kaon density
Physical Review D, 2013Co-Authors: William Detmold, Amy NicholsonAbstract:We present a lattice QCD calculation of the ground-state energy shifts of various baryons in a medium of pions or Kaons at a single value of the quark mass corresponding to a pion mass of m_\pi~390 MeV and a Kaon mass of m_K~540 MeV, and in a spatial volume V (4fm)^3. All systems are created using a canonical formalism in which quark propagators are contracted into correlation functions of fixed isospin/Kaon density. We study four different systems, \Sigma^+(\pi^+)^n, \Xi^0(\pi^+)^n, p(K^+)^n, and n(K^+)^n, for up to n=11 mesons. From the ground-state energy shifts we extract two- and three-body scattering parameters, as well as linear combinations of low-energy constants appearing in tree-level chiral perturbation theory.
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Kaon condensation with lattice qcd
Physical Review D, 2008Co-Authors: William Detmold, Kostas Orginos, Martin J Savage, Andre WalkerloudAbstract:Kaon condensation may play an important role in the structure of hadronic matter at densities greater than that of nuclear matter, as exist in the interior of neutron stars. We present the results of the first lattice QCD investigation of Kaon condensation obtained by studying systems containing up to 12 negatively charged Kaons. Surprisingly, the properties of the condensate that we calculate are remarkably well reproduced by leading order chiral perturbation theory. In our analysis, we also determine the three-Kaon interaction from the multi-Kaon systems and update our results for pion condensates.
Akaki Rusetsky - One of the best experts on this subject based on the ideXlab platform.
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Kaon nucleon scattering lengths from Kaonic deuterium experiments
European Physical Journal C, 2006Co-Authors: Ulfg Meisner, Udit Raha, Akaki RusetskyAbstract:The extraction of the S-wave Kaon–nucleon scattering lengths a0 and a1 from a combined analysis of existing Kaonic hydrogen and synthetic deuterium data has been carried out within the framework of a low-energy effective field theory. It turns out that with the present DEAR central values for the Kaonic hydrogen ground-state energy and width, a solution for a0 and a1 exists only in a restricted domain of input values for the Kaon–deuteron scattering length. Consequently, measuring this scattering length imposes stringent constraints on the theoretical description of the Kaon–deuteron interactions at low energies, if supplemented with DEAR data on Kaonic hydrogen.
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Kaon nucleon scattering lengths from Kaonic deuterium experiments
arXiv: Nuclear Theory, 2006Co-Authors: Ulfg Meisner, Udit Raha, Akaki RusetskyAbstract:The extraction of the S-wave Kaon-nucleon scattering lengths a0 and a1 from a combined analysis of existing Kaonic hydrogen and synthetic deuterium data has been carried out within the framework of a low-energy effective field theory. It turns out that with the present DEAR central values for the Kaonic hydrogen ground-state energy and width, a solution for a0 and a1 exists only in a restricted domain of input values for the Kaon-deuteron scattering length. Consequently, measuring this scattering length imposes stringent constraints on the theoretical description of the Kaon-deuteron interactions at low energies.
W Weise - One of the best experts on this subject based on the ideXlab platform.
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chiral dynamics of Kaon nucleon interactions revisited
European Physical Journal A, 2005Co-Authors: R Nisler, B Borasoy, W WeiseAbstract:The ¯N system close to threshold is analyzed in view of the new accurate DEAR Kaonic hydrogen data. The calculations are performed using chiral SU(3) effective field theory in combination with non-perturbative schemes based on coupled channels. Several variants of such approaches are compared with experimental data and the differences in the results are discussed. Coulomb and isospin-breaking effects turn out to be important and are both taken into account. The pole structure of the Λ(1405)-resonance close to the ¯N threshold is critically examined.
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chiral dynamics and the low energy Kaon nucleon interaction
arXiv: Nuclear Theory, 1995Co-Authors: Norbert Kaiser, P B Siegel, W WeiseAbstract:We examine the meson-baryon interaction in the strangeness S=-1 sector using an effective chiral Lagrangian. Potentials are derived from this Lagrangian and used in a coupled-channel calculation of the low energy observables. The potentials are constructed such that in the Born approximation the s-wave scattering amplitude is the same as that given by the effective chiral Lagrangian, up to order $q^2$. Comparison is made with the available low energy hadronic data of the coupled $K^-p, \Sigma \pi, \Lambda \pi$ system, which includes the $\Lambda (1405)$ resonance, $K^-p$ elastic and inelastic scattering, and the threshold branching ratios of the $K^-p$ decay. Good fits to the experimental data and estimates of previously unknown Lagrangian parameters are obtained.
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Kaons in baryonic matter
Nuclear Physics, 1994Co-Authors: Matthias F M Lutz, A Steiner, W WeiseAbstract:Abstract We investigate modifications of the Kaon mass in baryonic matter. It is rigorously established that at small density the in-medium Kaon masses are determined by the Kaon-nucleon scattering amplitude. Using empirical numbers there is no tendency towards s-wave K + condensation. We explore and discuss consequences of chiral symmetry for Kaon-nuclear systems.
Amy Nicholson - One of the best experts on this subject based on the ideXlab platform.
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baryon masses at nonzero isospin Kaon density
Physical Review Letters, 2013Co-Authors: William Detmold, Amy NicholsonAbstract:United States. Dept. of Energy. Outstanding Junior Investigator Program (Award DE-SC000-1784)
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baryon masses at nonzero isospin Kaon density
Physical Review D, 2013Co-Authors: William Detmold, Amy NicholsonAbstract:We present a lattice QCD calculation of the ground-state energy shifts of various baryons in a medium of pions or Kaons at a single value of the quark mass corresponding to a pion mass of m_\pi~390 MeV and a Kaon mass of m_K~540 MeV, and in a spatial volume V (4fm)^3. All systems are created using a canonical formalism in which quark propagators are contracted into correlation functions of fixed isospin/Kaon density. We study four different systems, \Sigma^+(\pi^+)^n, \Xi^0(\pi^+)^n, p(K^+)^n, and n(K^+)^n, for up to n=11 mesons. From the ground-state energy shifts we extract two- and three-body scattering parameters, as well as linear combinations of low-energy constants appearing in tree-level chiral perturbation theory.
