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We investigate a gauge extension of the Standard Model in light of the observed hints of lepton universality violation in $b \to c \ell \nu$ and $b \to s \ell^+ \ell^-$ decays at BaBar, Belle and LHCb. The model consists of an extended…

High Energy Physics - Phenomenology · Physics 2016-12-19 Sofiane M. Boucenna , Alejandro Celis , Javier Fuentes-Martin , Avelino Vicente , Javier Virto

A simple matching procedure is proposed to extract constraints on effective meson theories. In this way, a QCD prediction for the pion decay constant is found, F(pi)=2 m(pi)/pi, i.e. approximately 90MeV. The same procedure also determines…

High Energy Physics - Phenomenology · Physics 2007-05-23 Christopher Smith

The general analysis of lepton polarization asymmetries in rare B -> K^* l^+ l^- decay is investigated. Using the most general, model independent effective Hamiltonian, the general expressions of the longitudinal, normal and transversal…

High Energy Physics - Phenomenology · Physics 2009-10-31 T. M. Aliev , M. K. Cakmak , M. Savci

Recent measurements of kaon decays provide new information about CKM unitarity, lepton universality, and discrete symmetries. KLOE-2, the proposed extension of the kaon physics program at Frascati, will extend the world data set on kaon…

High Energy Physics - Experiment · Physics 2009-03-03 Matthew Moulson

Pion $\beta$ decay, $\pi^+ \to\pi^0 e^+ \nu_e$, offers a pristine way to measure the CKM matrix element $V_{ud}$ in a purely mesonic system, with excellent control over the hadronic matrix elements. We review the physics goals and current…

High Energy Physics - Phenomenology · Physics 2024-03-29 Martin Hoferichter

We study the Schwinger model with $N_{\rm f} \geq 2$ degenerate fermion flavors, by means of lattice simulations. We use dynamical Wilson fermions for $N_{\rm f} = 2$, and re-weighted quenched configurations for overlap-hypercube fermions…

High Energy Physics - Lattice · Physics 2023-10-16 Jaime Fabián Nieto Castellanos , Ivan Hip , Wolfgang Bietenholz

The Belle Collaboration presented three recent Belle analyses: The search for $B\rightarrow l\nu\gamma$ ($l = e, \mu$) with improved hadronic tagging, the search for $B\rightarrow \mu \nu_\mu$ with inclusive tagging and the test of lepton…

High Energy Physics - Experiment · Physics 2019-06-18 Markus Tobias Prim

The status of chiral perturbation theory in the meson sector is illustrated with several topical examples. The longtime discrepancy between theory and experiment for the charged pion polarizabilities has now been resolved in favour of the…

High Energy Physics - Phenomenology · Physics 2015-10-07 Gerhard Ecker

The electric ${\alpha}_{\pi}$ and magnetic ${\beta}_{\pi}$ charged pion Compton polarizabilities are of fundamental interest in the low-energy sector of quantum chromodynamics (QCD). They characterize the induced dipole moments of the pion…

High Energy Physics - Phenomenology · Physics 2022-05-23 Murray Moinester

Neutrinoless double beta decay, if detected, would prove that neutrinos are Majorana fermions and provide the direct evidence for lepton number violation. If such decay would exist in nature, then $\pi^-\pi^-\to ee$ and $\pi^-\to\pi^+ ee$…

High Energy Physics - Lattice · Physics 2019-12-04 Xin-Yu Tuo , Xu Feng , Lu-Chang Jin

Rare kaon decays provide unique opportunity to test the Standard Model and probe its possible extensions. The final result on the lepton universality test by measuring the ratio R_K = G(K+- to e+- nu)/G(K+- to mu+- nu) is presented as well…

High Energy Physics - Experiment · Physics 2014-12-02 Venelin Kozhuharov

We show that processes involving pions that remain very near their mass-shell can be reliably computed in the pionless effective field theory, with the pion integrated in as a heavy field. As an application, we compute the pion-deuteron…

Nuclear Theory · Physics 2009-11-07 Silas R. Beane , Martin J. Savage

We present an improved Standard-Model (SM) prediction for the dilepton decay of the neutral pion. The loop amplitude is determined by the pion transition form factor for $\pi^0\to\gamma^*\gamma^*$, for which we employ a dispersive…

High Energy Physics - Phenomenology · Physics 2022-05-02 Martin Hoferichter , Bai-Long Hoid , Bastian Kubis , Jan Lüdtke

We consider lepton-antilepton annihilation into a fermion-antifermion pair at variable c.m. energy. We propose for this process a simple parametrization of the virtual effects of the most general model of new physics of…

High Energy Physics - Phenomenology · Physics 2009-10-31 M. Beccaria , F. M. Renard , S. Spagnolo , C. Verzegnassi

Complex poles of the unitarized pi-pi scattering amplitude in nuclear matter are studied. Partial restoration of chiral symmetry is modeled by the decrease of in-medium pion decay constant f*_{pi}. For large chiral restoration…

High Energy Physics - Phenomenology · Physics 2009-11-07 K. Yokokawa , T. Hatsuda , A. Hayashigaki , T. Kunihiro

Non-leptonic hyperon weak decays are investigated in the SU(3) Skyrme model. We use a collective coordinate scheme, following the approach in which the symmetry breaking terms in the strong effective action are diagonalized exactly. To…

High Energy Physics - Phenomenology · Physics 2009-10-31 D. Gomez Dumm , A. J. Garcia , N. N. Scoccola

In this talk I review theoretical predictions for CP violation in non-leptonic hyperon decays in the Standard Model and models beyond. In the Standard Model the CP violating observable $A$ in the polarization asymmetries of $\Lambda \to p…

High Energy Physics - Phenomenology · Physics 2007-05-23 Xiao-Gang He

The measurement of the exclusive light hadron decays of the psi'' in e+e- experiments with significant interference between the psi'' and non-resonance continuum amplitudes is discussed. The radiative correction and the Monte Carlo…

High Energy Physics - Phenomenology · Physics 2010-11-05 P. Wang , X. H. Mo , C. Z. Yuan

We apply hard pion Chiral Perturbation Theory to charmonium decays to $\pi\pi$, $KK$ and $\eta\eta$. We first discuss why we expect to be able to provide results for the chiral logarithms in $\chi_{c0}$ and $\chi_{c2}$ decays to two…

High Energy Physics - Phenomenology · Physics 2015-05-30 Johan Bijnens , Ilaria Jemos

Exclusive semi-leptonic decays of the tau lepton offer a clean probe to study the hadronization of QCD currents in its non-perturbative regime and learn about resonance dynamics, which drives strong interactions in these processes. In this…

High Energy Physics - Phenomenology · Physics 2015-05-13 Pablo Roig