scholarly journals QED factorization of two-body non-leptonic and semi-leptonic B to charm decays

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Martin Beneke ◽  
Philipp Böer ◽  
Gael Finauri ◽  
K. Keri Vos
Keyword(s):  
Theoretical Calculations ◽  
General Structure ◽  
Percent Level ◽  
Careful Analysis ◽  
Decay Rates ◽  
Tree Amplitude ◽  
Leptonic Decays ◽  
Amplitude Coefficient ◽  
Heavy Quark Limit ◽  
Qed Effects

Abstract The QCD×QED factorization is studied for two-body non-leptonic and semi-leptonic B decays with heavy-light final states. These non-leptonic decays, like $$ {\overline{B}}_{(s)}^0\to {D}_{(s)}^{+}{\pi}^{-} $$ B ¯ s 0 → D s + π − and $$ {\overline{B}}_d^0\to {D}^{+}{K}^{-} $$ B ¯ d 0 → D + K − , are among the theoretically cleanest non-leptonic decays as penguin loops do not contribute and colour-suppressed tree amplitudes are suppressed in the heavy-quark limit or even completely absent. Advancing the theoretical calculations of such decays requires therefore also a careful analysis of QED effects. Including QED effects does not alter the general structure of factorization which is analogous for both semi-leptonic and non-leptonic decays. For the latter, we express our result as a correction of the tree amplitude coefficient a1. At the amplitude level, we find QED effects at the sub-percent level, which is of the same order as the QCD uncertainty. We discuss the phenomenological implications of adding QED effects in light of discrepancies observed between theory and experimental data, for ratios of non-leptonic over semi-leptonic decay rates. At the level of the rate, ultrasoft photon effects can produce a correction up to a few percent, requiring a careful treatment of such effects in the experimental analyses.

Sulphate reduction, organic matter decomposition and pyrite formation

1985 ◽  
Vol 315 (1531) ◽  
pp. 25-38 ◽  
Keyword(s):  
Organic Matter ◽  
Theoretical Calculations ◽  
Decay Rates ◽  
Sulphate Reduction ◽  
Limiting Factors ◽  
Burial Rate ◽  
First Order Kinetics ◽  
Bacterial Sulphate Reduction ◽  
Bottom Waters ◽  
Pyrite Formation

Laboratory, field, and theoretical studies have shown that the rate of bacterial sulphate reduction during early diagenesis depends primarily on the reactivity of sedimentary organic matter whose decomposition follows first-order kinetics, with rate constants varying over six orders of magnitude. Decay rates decrease with decreasing sediment burial rate and, for a given sediment, with depth, because o f the successive utilization by bacteria of less and less reactive organic compounds. High burial (and bioturbation) rates enable reactive compounds to become available for sulphate reduction, at depth, which otherwise would be destroyed by molecular oxygen at or above the sediment-water interface. An important consequence of bacterial sulphate reduction is the formation of sedimentary pyrite, FeS 2 . In normal marine sediments (those deposited in oxygenated bottom waters) pyrite formation is limited by the concentration and reactivity of organic matter, whereas in euxinic (sulphidic) basins pyrite is limited by the abundance and reactivity of detrital iron minerals, and in non-saline swamp and lake sediments by the low levels of dissolved sulphate found in fresh water. Because of these differences in limiting factors, the three environments can be distinguished in both modern sediments and ancient rocks by plots of organic carbon, C against pyrite sulphur, S. Values of the C:S ratio based on theoretical calculations indicate that worldwide the bulk of organic matter burial has shifted considerably between these environments over Phanerozoic time.

scholarly journals Asymptotic behavior of 2D stably stratified fluids with a damping term in the velocity equation

2021 ◽  
Author(s):  
Roberta Bianchini ◽  
Roberto Natalini
Keyword(s):  
Asymptotic Behavior ◽  
Boussinesq Equations ◽  
Careful Analysis ◽  
Decay Rates ◽  
Smooth Solutions ◽  
Damping Term ◽  
Bilinear Estimates ◽  
Linearized Problem ◽  
Time Decay Rates ◽  
Velocity Equation

This article deals with the asymptotic behavior of the two-dimensional inviscid Boussinesq equations with a damping term in the velocity equation. Precisely, we provide the time-decay rates of the smooth solutions to that system. The key ingredient is a careful analysis of the Green kernel of the linearized problem in Fourier space, combined with bilinear estimates and interpolation inequalities for handling the nonlinearity.

A new variational approach and its application toheavy quarkonia

2021 ◽  
Vol 67 (1 Jan-Feb) ◽  
pp. 33
Author(s):  
R. Manzoor ◽  
J. Ahmed ◽  
A. Raya
Keyword(s):  
Wave Equation ◽  
Theoretical Calculations ◽  
Heavy Meson ◽  
Decay Rates ◽  
Model Parameters ◽  
S Wave ◽  
Analytical Functions ◽  
Running Coupling ◽  
Running Coupling Constant ◽  
The Matrix

By combining the variational principle with Heisenberg uncertaintyprinciple in an effective Hamiltonian for heavy flavored mesons, we in-troduce a framework to estimate masses and radii of these states froman analytical constraint. In a novel manner, a model for quark velocityand a model for quark momentum width are introduced. These kinemat-ical model parameters are obtained as analytical functions of inter quarkseparation in heavy quarkonia. The values of such quark parameters arethen used in the calculation of S-wave annihilation decay rates of \bar{c}c and\bar{b} b. To test the accuracy of our technique we first calculate the spin averaged masses, scalar radii and annihilation decay rates of charmoniumand bottomonium without and with relativistic corrections by solving theSchrödinger wave equation with the appropriate parametrization of the Song-Lin potential. The Schrödinger wave equation is solved numericallywith the matrix Numerov method and we observe a good agreement withthe experimental measurements and other theoretical calculations and extract strong running coupling constant for \bar{c}c and \bar{b}b systems. In non rel-ativistic settings, heavy meson spectra have been obtained and extended to rather higher excited states within our framework by using bare masses of c and b quarks which we have extracted from analysis of experimentaldata

scholarly journals Precision Calculations in Supersymmetric Theories

2013 ◽  
Vol 2013 ◽  
pp. 1-64 ◽  
Author(s):  
L. Mihaila
Keyword(s):  
Theoretical Calculations ◽  
Gauge Coupling ◽  
Decay Rates ◽  
Boson Mass ◽  
Experimental Accuracy ◽  
The Standard Model ◽  
Component Field ◽  
Field Formalism ◽  
The One ◽  
Supersymmetric Theories

In this paper we report on the newest developments in precision calculations in supersymmetric theories. An important issue related to this topic is the construction of a regularization scheme preserving simultaneously gauge invariance and supersymmetry. In this context, we discuss in detail dimensional reduction in component field formalism as it is currently the preferred framework employed in the literature. Furthermore, we set special emphasis on the application of multi-loop calculations to the analysis of gauge coupling unification, the prediction of the lightest Higgs boson mass, and the computation of the hadronic Higgs production and decay rates in supersymmetric models. Such precise theoretical calculations up to the fourth order in perturbation theory are required in order to cope with the expected experimental accuracy on the one hand and to enable us to distinguish between the predictions of the Standard Model and those of supersymmetric theories on the other hand.

scholarly journals Leptonic decays of strange particles - C.E.R.N. work on weak interactions

1965 ◽  
Vol 285 (1401) ◽  
pp. 202-213 ◽  
Keyword(s):  
Weak Interactions ◽  
Mass Difference ◽  
Form Factors ◽  
Strange Particle ◽  
Branching Ratios ◽  
Decay Rates ◽  
Leptonic Decays ◽  
Muon Polarization ◽  
Constant Form ◽  
Three Body

Experimental results on strange particle leptonic decays are summarized and compared with predictions based on the Δ S = + Δ Q , |Δ I | = ½ and Δ S ǂ 2 rules, CP invariance and electron-muon universality. Recent (and still preliminary) results on K 0 1.2 → π ± + e ∓ + v , K + → π + + π ± + e ∓ + v and Ʃ ± → N + ( μ or e ) ± + v are compatible with little (< 10%) or no violation of the Δ S = + Δ Q rule. Three-body leptonic decay rates of K + and K 0 disagree by about two standard deviations with the |Δ I = ½ rule prediction, but the agreement is restored if ca . 10% |Δ I | = 3/2 admixture is allowed. No Δ S = 2, ≡ - → N + e - + v or ≡ 0 → p + e - + v decays have been observed to the level of ca . 1% of the normal decays. All the data are in good agreement with time reversal or CP invariance and with the assumptions that the lepton pair is coupled locally and that electrons and muons behave identically apart from effects of their mass difference. † The branching ratios for the various hyperon leptonic decays and the observed V-A form for A β decay are explained qualitatively by the theory of Cabibbo, for example, but the data are not yet precise enough for a sharp test of the theory. New data on K + → π 0 + ( e or μ ) + + v spectra, branching ratios and muon polarization indicate that the interaction is of the vector form with approximately constant form factors and that the form factor ratio f - / f + is of order 1 or compatible with 0, as in the case of K 0 2 → π ± + e ∓ + v .

scholarly journals Exploring QED Effects to Diphoton Production at Hadron Colliders

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 994
Author(s):  
Leandro Cieri ◽  
German Sborlini
Keyword(s):  
Invariant Mass Distribution ◽  
Percent Level ◽  
New Physics ◽  
Hadron Colliders ◽  
Subtraction Method ◽  
Experimental Conditions ◽  
Event Reconstruction ◽  
Phenomenological Studies ◽  
Qed Effects ◽  
The Impact

In this article, we report phenomenological studies about the impact of O(α) corrections to diphoton production at hadron colliders. We explore the application of the Abelianized version of the qT-subtraction method to efficiently compute NLO QED contributions, taking advantage of the symmetries relating QCD and QED corrections. We analyze the experimental consequences due to the selection criteria and we find percent-level deviations for Mγγ>1TeV. An accurate description of the tail of the invariant mass distribution is very important for new physics searches which have the diphoton process as one of their main backgrounds. Moreover, we emphasize the importance of properly dealing with the observable photons by reproducing the experimental conditions applied to the event reconstruction.

scholarly journals $$\rho $$–Meson Form-factors in Point form of Poincaré-Invariant Quantum Mechanics

2021 ◽  
Vol 62 (3) ◽  
Author(s):  
V. Yu. Haurysh ◽  
V. V. Andreev
Keyword(s):  
Experimental Data ◽  
Quantum Mechanics ◽  
Magnetic Moment ◽  
Theoretical Calculations ◽  
Form Factors ◽  
Relativistic Quark Model ◽  
Leptonic Decays ◽  
Rho Meson ◽  
Point Form ◽  
Invariant Quantum

AbstractForm-factors investigation of $$\rho ^{\pm }$$ ρ ± –mesons was carried out within the framework of the relativistic quark model, based on point form of Poincaré-invariant quantum mechanics taking into account the internal structure of constituent quarks. It is shown that the parameters of the model obtained from the condition of the agreement of theoretical calculations with experimental data on leptonic decays for light $$\pi ^{\pm }$$ π ± — and $$\rho ^{\pm }$$ ρ ± –mesons lead to the results correlating with calculations in models based on light-front and instant forms of dynamics. The proposed scheme for the combined description of lepton transitions of pseudoscalar and vector mesons that is based on point form of dynamics, leads to the results on the magnetic moment of $$\rho ^{\pm }$$ ρ ± –meson correlating with the experimental data and other models.

LEPTONIC DECAYS OF VECTOR MESONS

2005 ◽  
Vol 14 (06) ◽  
pp. 909-921 ◽  
Author(s):  
SHASHANK BHATNAGAR
Keyword(s):  
Asymptotic Behavior ◽  
General Structure ◽  
Leptonic Decay ◽  
Vector Mesons ◽  
Decay Constants ◽  
Leptonic Decays ◽  
Instantaneous Approximation

In this paper, the general structure of leptonic decay constants of vector mesons is evaluated in the framework of the Bethe–Salpeter equation under the Covariant Instantaneous Ansatz (CIA), which is a Lorentz-invariant generalization of Instantaneous Approximation (IA). The numerical values of fV in this CIA framework are on the low side in comparison to recent calculations of these quantities. However, the overall asymptotic behavior of fV is in conformity with QCD predictions.

scholarly journals NLO prediction for the decays $\tau \to \ell \ell'\ell' \nu \bar \nu$ and $\mu \to e e e \nu \bar\nu$

2019 ◽  
Author(s):  
Matteo Fael
Keyword(s):  
Phase Space ◽  
Weak Interactions ◽  
Structure Constant ◽  
Branching Ratios ◽  
Decay Rates ◽  
Fine Structure Constant ◽  
Space Region ◽  
Leptonic Decays ◽  
Charged Leptons ◽  
Lepton Flavour

These proceedings review the differential decay rates and the branching ratios of the tau and muon decays \tau \to \ell \ell' \ell' \nu \bar\nuτ→ℓℓ′ℓ′νν‾ (with \ell,\ell'=\mu,eℓ,ℓ′=μ,e) and \mu \to e e e \nu \bar \nuμ→eeeνν‾ in the Standard Model at NLO. These five-body leptonic decays are a tool to study the Lorentz structure of weak interactions and to test lepton flavour universality. They are also a source of SM background to searches for the lepton-flavour-violating decays \mu \to e e eμ→eee and \tau \to \ell \ell' \ell'τ→ℓℓ′ℓ′.Even if the shift in the branching ratios induced by radiative corrections turns out to be small and of order 1% — mainly due to a running effect of the fine structure constant — locally in the phase space these corrections can reach the 5 - 10% level, depending on the applied cuts. We found for instance that in the phase space region where the neutrino energies are small, and the momenta of the three charged leptons have a similar signature as in \mu \to eeeμ→eee and \tau \to \ell \ell'\ell'τ→ℓℓ′ℓ′, the NLO corrections decrease the leading-order prediction by about 10 - 20%.

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