scholarly journals HFLAV $τ$ branching fractions fit and measurements of Vus with $τ$ lepton data

2019 ◽  
Author(s):  
Alberto Lusiani
Keyword(s):  
Matrix Element ◽  
Branching Fraction ◽  
Branching Fractions ◽  
Final States ◽  
Ckm Matrix ◽  
The Status ◽  
Global Fit

We report the status of the Heavy Flavour Averaging Group (HFLAV) averages of the \tauτ lepton measurements We then update the latest published HFLAV global fit of the \tauτ lepton branching fractions (Spring 2017) with recent results by . We use the fit results to update the Cabibbo-Kobayashi-Maskawa (CKM) matrix element \left|V_{us}\right||Vus| measurements with the \tauτ branching fractions. We combine the direct \tauτ branching fraction measurements with indirect predictions using kaon branching fractions measurements to improve the determination of \left|V_{us}\right||Vus| using \tauτ branching fractions. The \left|V_{us}\right||Vus| determinations based on the inclusive branching fraction of \tauτ to strange final states are about 3\sigma3σ lower than the \left|V_{us}\right||Vus| determination from the CKM matrix unitarity.

scholarly journals DETERMINATION OF |Vcb| AND RELATED RESULTS FROM BABAR

2005 ◽  
Vol 20 (02n03) ◽  
pp. 557-560
Author(s):  
◽  
MASAHIRO MORII
Keyword(s):  
Matrix Element ◽  
Branching Fraction ◽  
Precise Determination ◽  
Ckm Matrix ◽  
Hadron Mass ◽  
Global Fit ◽  
Inclusive Semileptonic Decays ◽  
Babar Detector ◽  
Energy Moments

The CKM matrix element amplitude |Vcb| was determined using the data collected by the BABAR detector. The partial branching fraction, lepton-energy moments, and hadron-mass moments were measured in inclusive semileptonic decays B→Xcℓν. A global fit to a Heavy-Quark-Expansion calculation allowed precise determination of |Vcb|, mb, mc, ℬ(B→Xcℓν) and four non-perturbative parameters.

scholarly journals QUARK MIXING AND CP VIOLATION — THE CKM MATRIX

2006 ◽  
Vol 21 (08n09) ◽  
pp. 1724-1737 ◽  
Author(s):  
ULRICH NIERSTE
Keyword(s):  
Neutral Current ◽  
New Physics ◽  
Tree Level ◽  
B Decays ◽  
Ckm Matrix ◽  
Penguin Decays ◽  
The Status ◽  
First Results ◽  
Global Fit

I summarize the theoretical progress in the determination of the CKM elements since Lepton-Photon 2003 and present the status of the elements and parameters of the Cabibbo-Kobayashi-Maskawa (CKM) matrix. One finds |Vus| = 0.2227 ± 0.0017 from K and τ decays and |Vcb| = (41.6 ± 0.5) · 10-3 from inclusive semileptonic B decays. The unitarity triangle can now be determined from tree-level quantities alone and the result agrees well with the global fit including flavour-changing neutral current (FCNC) processes, which are sensitive to new physics. From the global fit one finds the three CKM angles θ12 = 12.9° ± 0.1°, θ23 = 2.38° ± 0.03° and θ13 = 0.223° ± 0.007° in the standard PDG convention. The CP phase equals [Formula: see text] at 1σ CL and [Formula: see text] at 2σ CL. A major progress are first results from fully unquenched lattice QCD computations for the hadronic quantities entering the UT fit. I further present the calculation of three-loop QCD corrections to the charm contribution in [Formula: see text] decays, which removes the last relevant theoretical uncertainty from the [Formula: see text] system. Finally I discuss mixing-induced CP asymmetries in [Formula: see text] penguin decays, whose naive average is below its Standard Model value by 3σ.

scholarly journals Study of the B → Xcℓν Decays and Determination of |Vcb|

2005 ◽  
Vol 20 (16) ◽  
pp. 3644-3647
Author(s):  
◽  
Vladimir Golubev
Keyword(s):  
Matrix Element ◽  
Heavy Quark ◽  
Electron Energy ◽  
Branching Fraction ◽  
Form Factors ◽  
Ckm Matrix ◽  
Mass Distributions ◽  
Babar Detector ◽  
Decay Form

We report studies of semileptonic decays, B → Xcℓν, based on a sample of 88 million [Formula: see text] events recorded with the BABAR detector. We have measured four moments of the electron energy and hadronic mass distributions and determined the inclusive branching fraction, the CKM matrix element |Vcb|, and other heavy quark parameters, using Heavy Quark Expansions in the kinetic mass scheme. In addition, we have studied a large sample of B0 → D*-ℓ+ν decays and extracted the decay form factors and |Vcb|.

scholarly journals Status and progress of the HFLAV-Tau group activities

2019 ◽  
Vol 218 ◽  
pp. 05002 ◽  
Author(s):  
Alberto Lusiani
Keyword(s):  
Matrix Element ◽  
Group Work ◽  
Branching Fractions ◽  
Tau Lepton ◽  
Group Activities ◽  
Lepton Universality ◽  
The Status ◽  
Global Fit

We report the status and progress of the Heavy Flavour Averaging Group work on the global fit of τ tau lepton branching fractions, on the lepton universality tests and on the measurement of the Cabibbo-Kobayashi-Maskawa matrix element |Vus| using τ lepton measurements. We also review the prospects for improving the precision of the |Vus| measurement.

scholarly journals K → μ+μ− as a clean probe of short-distance physics

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Avital Dery ◽  
Mitrajyoti Ghosh ◽  
Yuval Grossman ◽  
Stefan Schacht
Keyword(s):  
Matrix Element ◽  
Standard Model ◽  
Short Distance ◽  
Time Dependent ◽  
Final States ◽  
Interference Effects ◽  
Fundamental Theory ◽  
Long Distance ◽  
Ckm Matrix ◽  
The Standard Model

Abstract The K → μ+μ− decay is often considered to be uninformative of fundamental theory parameters since the decay is polluted by long-distance hadronic effects. We demonstrate that, using very mild assumptions and utilizing time-dependent interference effects, ℬ(KS → μ+μ−)ℓ=0 can be experimentally determined without the need to separate the ℓ = 0 and ℓ = 1 final states. This quantity is very clean theoretically and can be used to test the Standard Model. In particular, it can be used to extract the CKM matrix element combination $$ \mid {V}_{ts}{V}_{td}\sin \left(\beta +{\beta}_s\right)\mid \approx \mid {A}^2{\lambda}^5\overline{\eta}\mid $$ ∣ V ts V td sin β + β s ∣ ≈ ∣ A 2 λ 5 η ¯ ∣ with hadronic uncertainties below 1%.

scholarly journals B → D*lv at non-zero recoil

2018 ◽  
Vol 175 ◽  
pp. 13003 ◽  
Author(s):  
Alejandro Vaquero Avilés-Casco ◽  
Carleton DeTar ◽  
Daping Du ◽  
Aida El-Khadra ◽  
Andreas Kronfeld ◽  
...  
Keyword(s):  
Matrix Element ◽  
Decay Rate ◽  
Form Factors ◽  
Heavy Quarks ◽  
Experimental Measurements ◽  
Ckm Matrix ◽  
Preliminary Results ◽  
Future Plans

We present preliminary results from our analysis of the form factors for the B → D*lv decay at non-zero recoil. Our analysis includes 15 MILC asqtad ensembles with Nf = 2 + 1 flavors of sea quarks and lattice spacings ranging from a ≈ 0.15 fm down to 0.045 fm. The valence light quarks employ the asqtad action, whereas the heavy quarks are treated using the Fermilab action. We conclude with a discussion of future plans and phenomenological implications. When combined with experimental measurements of the decay rate, our calculation will enable a determination of the CKM matrix element |Vcb|.

Measurement of |Vcb| with $\bar{B}^0 \rightarrow D^{*+} \ell^- \bar{\nu}$ at CLEO

2001 ◽  
Vol 16 (supp01b) ◽  
pp. 639-641
Author(s):  
◽  
Daniel Cronin-Hennessy
Keyword(s):  
Form Factor ◽  
Matrix Element ◽  
Decay Rate ◽  
Branching Fraction ◽  
Ckm Matrix ◽  
Kinematic Point

We determine the CKM matrix element, |Vcb|, by measuring the differential decay rate of B→D*+ℓν as a function of w=vB · vD*. We extrapolate the decay rate to the kinematic point, w=1, where the form factor, ℱ(w), is accurately predicted by theory. We find ℱ(1)|Vcb|=0.0424±0.0018( stat. )±0.0019( syst. ). Integration of the differential decay rate, dΓ/dw, yields the B→D*+ℓν branching fraction, ℬ(B→D*+ℓν)=(5.66±0.29±0.33)%. The data are derived from 3.3 million [Formula: see text] events collected by the CLEO detector at CESR.

scholarly journals Recent results from BABAR

2020 ◽  
Vol 235 ◽  
pp. 04001
Author(s):  
J. William Gary
Keyword(s):  
Data Collection ◽  
Direct Measurement ◽  
Decay Channel ◽  
Branching Fraction ◽  
Branching Fractions ◽  
Babar Collaboration ◽  
Lepton Number ◽  
Lepton Flavor ◽  
The Third

The BABAR Collaboration at SLAC continues to produce a wide variety of publications on interesting and unique topics despite having ceased data-collection operations more than 10 years ago. Presented here are the results of three recent studies. The first is on the direct measurement of the B± → K± X(3872) branching fraction, allowing the first determination of the branching fractions of the exotic X(3872) charmonium state. The second is a publication on the first observation of the D0 → K−π+e+e− branching fraction. The third is on searches for lepton flavor and lepton number violating decays in D0 meson decays, resulting in improvements over existing limits by factors that vary from 20 to almost 800 depending on the D0 decay channel.

scholarly journals Precise determination of αS( $ m_{Z^0 } $ ) from a global fit of energy-energy correlations to NNLO+NNLL predictions

2019 ◽  
Vol 206 ◽  
pp. 05002
Author(s):  
A. Kardos ◽  
S. Kluth ◽  
G. Somogyi ◽  
Z. Tulipánt ◽  
A. Verbytskyi
Keyword(s):  
Strong Coupling ◽  
Precise Determination ◽  
Strong Coupling Constant ◽  
Final States ◽  
Leading Order ◽  
Coupling Constant ◽  
Global Fit ◽  
Hadronic Final States

We present a determination of the strong coupling constant αS( $ m_{Z^0 } $ ) using a global fit of theory predictions in next-to-next-next-leading-order (NNLO) combined with resummed predictions at the next-to-next-leading-log level (NNLL) [bibrR11]. The predictions are compared to distributions of energy-energy correlations measured in e+e−annihilation to hadronic final states by experiments at the e+e−colliders LEP, PETRA, TRISTAN and PEP. The predictions are corrected for hadronisation effects using the modern generator programs Sherpa 2.2.4 and Herwig 7.1.1.

scholarly journals An experimentalist’s guide to the semileptonic bottom to charm branching fractions

2018 ◽  
Vol 33 (32) ◽  
pp. 1850176 ◽  
Author(s):  
Matthew Rudolph
Keyword(s):  
Branching Fraction ◽  
Branching Fractions ◽  
Current Status ◽  
Experimental Measurements ◽  
Final States

This work summarizes the current status of the measured semileptonic branching fractions [Formula: see text]. The sum of exclusive measurements is compared with the inclusive determination, accounting for isospin extrapolation. Further derived quantities are computed, taking into account different explanations for the unmeasured components of the total branching fraction. These quantities focus on the charge breakdown of the final states, and are designed for use as inputs or comparisons in future experimental measurements.

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