Status of |Vcb| and |Vub| CKM matrix elements

Ricciardi, Giulia

doi:10.1063/1.4938654

Cited by 11 publications

(9 citation statements)

References 125 publications

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“…We note that with the reduced error on the ∆B = 2 paramete ξ , promised in [149], the error on γ will decrease down to 2.3 • . The indirect fits done by UTfit [150] and CKMfitter [151] that are summarized in [16] in good agreement with our results. We note however, that these two groups included in their analyses the information from tree level decays, whereas we decided not to use it because of discrepancies between inclusive and exclusive determinations of |V ub | and |V cb |.…”

Section: Modelssupporting

confidence: 87%

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Flavour Expedition to the Zeptouniverse

Buras

2015

Proceedings of Flavorful Ways to New Physics — PoS(FWNP)

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After the completion of the Standard Model (SM) through the Higgs discovery in 2012 particle physicists are waiting for the discovery of new particles either directly with the help of the Large Hadron Collider (LHC) or indirectly through quantum fluctuations causing certain rare processes to occur at different rates than predicted by the SM. While the later route is very challenging, requiring very precise theory and experiment, it allows in principle a much higher resolution of short distance scales than it is possible with the help of the LHC. In fact in the coming flavour precision era, in which the accuracy of the measurements of rare processes and of the relevant lattice QCD calculations will be significantly increased, there is a good chance that we may get an insight into the scales as short as 10 −21 m (Zeptouniverse) corresponding to energy scale of 200 TeV or even shorter distance scales. We discuss the requirements that have to be met for such a flavour expedition to the Zeptouniverse to be successful. In particular we emphasize the power of correlations between flavour observables in the search for New Physics (NP) and identify a number of correlations that could allow to discover NP even if it would appear at the level of 20% of the SM contributions. The correlation between B(K + → π + νν), B(B s → µ + µ − ) and γ extracted from tree-level decays within the SM is one of them. After presenting the simplest correlations in CMFV and U(2) 3 models we address the recent data on B s,d → µ + µ − and the anomalies in B d → K(K * )µ + µ − , including breakdown of lepton flavour universality, in the context of Z -models with quark flavour violating neutral couplings. A brief discussion of leptoquark models is also given. We emphasize the correlations of B d → K(K * )µ + µ − with B d → K(K * )νν that allow to distinguish between various explanations of the anomalies in question.Finally we summarize the recent study of K → πνν and B d,s → µ + µ − decays which demonstrates that these decays play important roles in finding out what happens in the Zeptouniverse. Flavorful Ways to New Physics

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Section: Modelssupporting

confidence: 87%

“…Concerning the second item one needs the clarification of the discrepancies between inclusive and exclusive determinations of |V cb | and |V ub | from tree-level decays [16,17]. The present status of these determinations is as follows.…”

Section: Basic Requirements For Reaching the Zeptouniversementioning

confidence: 99%

Flavour Expedition to the Zeptouniverse

Buras

2015

Proceedings of Flavorful Ways to New Physics — PoS(FWNP)

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“…Although this is in principle the optimal strategy, it is currently marred by disagreements between the exclusive and inclusive determinations of both |V ub | and |V cb | -for recent reviews see [53][54][55]. We proceed to present the latest results of both determinations, as well as our weighted average, with which we will give the SM predictions in what we call strategy A.…”

Section: Determination Of the Branching Ratiosmentioning

confidence: 99%

K + → π + ν ν ¯ $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ and K L → π 0 ν ν ¯ $$ {K}_L\to {\pi}^0\nu \overline{\nu} $$ in the Standard Model: status and perspectives

Buras

Buttazzo

Girrbach-Noe

et al. 2015

J. High Energ. Phys.

259

150

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In view of the recent start of the NA62 experiment at CERN that is expected to measure the K + → π + νν branching ratio with a precision of 10%, we summarise the present status of this promising decay within the Standard Model (SM). We do likewise for the closely related K L → π 0 νν, which will be measured by the KOTO experiment around 2020. As the perturbative QCD and electroweak corrections in both decays are under full control, the dominant uncertainties within the SM presently originate from the CKM parameters |V cb |, |V ub | and γ. We show this dependence with the help of analytic expressions as well as accurate interpolating formulae. Unfortunately a clarification of the discrepancies between inclusive and exclusive determinations of |V cb | and |V ub | from tree-level decays will likely require results from the Belle II experiment available at the end of this decade. Thus we investigate whether higher precision on both branching ratios is achievable by determining |V cb |, |V ub | and γ by means of other observables that are already precisely measured. In this context ε K and ∆M s,d , together with the expected progress in QCD lattice calculations will play a prominent role. We find B(K + → π + νν) = (9.11 ± 0.72) × 10 −11 and B(K L → π 0 νν) = (3.00 ± 0.30) × 10 −11 , which is more precise than using averages of the present tree-level values of |V cb |, |V ub | and γ. Furthermore, we point out the correlation between B(K + → π + νν), B(B s → µ + µ − ) and γ within the SM, that is only very weakly dependent on other CKM parameters. Finally, we update the correlation of K L → π 0 νν with the ratio ε /ε in the SM taking the recent progress on ε /ε from lattice QCD and the large N approach into account.

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“…(1) are from the decays B → π ν and B → D * ν (where = e, µ) and use hadronic form factors from lattice QCD [2,3]. The discrepancy between the exclusive and inclusive results is a long-standing puzzle in flavor physics [4][5][6], and right-handed currents beyond the Standard Model have been considered as a possible explanation [7][8][9][10]. New lattice QCD calculations of the B → π form factors published recently yield somewhat higher values of |V ub | excl.…”

Section: Introductionmentioning

confidence: 99%

Λb→pℓ−ν¯
Detmold
¹
,
Lehner
²
,
Meinel
³

2015
Phys. Rev. D
256
17
418
2
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Measurements of the Λ b → pl −ν l and Λ b → Λ c l −ν l decay rates can be used to determine the magnitudes of the Cabibbo-Kobayashi-Maskawa matrix elements V ub and V cb , provided that the relevant hadronic form factors are known. Here we present a precise calculation of these form factors using lattice QCD with 2 þ 1 flavors of dynamical domain-wall fermions. The b and c quarks are implemented with relativistic heavy-quark actions, allowing us to work directly at the physical heavy-quark masses. The lattice computation is performed for six different pion masses and two different lattice spacings, using gauge-field configurations generated by the RBC and UKQCD Collaborations. The b → u and b → c currents are renormalized with a mostly nonperturbative method. We extrapolate the form factor results to the physical pion mass and the continuum limit, parametrizing the q 2 dependence using z expansions. The form factors are presented in such a way as to enable the correlated propagation of both statistical and systematic uncertainties into derived quantities such as differential decay rates and asymmetries. Using these form factors, we present predictions for the Λ b → pl −ν l and Λ b → Λ c l −ν l differential and integrated decay rates. Combined with experimental data, our results enable determinations of jV ub j, jV cb j, and jV ub =V cb j with theory uncertainties of 4.4%, 2.2%, and 4.9%, respectively.

show abstract

Status of |Vcb| and |Vub| CKM matrix elements

Cited by 11 publications

References 125 publications

Flavour Expedition to the Zeptouniverse

Flavour Expedition to the Zeptouniverse

K + → π + ν ν ¯ $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ and K L → π 0 ν ν ¯ $$ {K}_L\to {\pi}^0\nu \overline{\nu} $$ in the Standard Model: status and perspectives

Λb→pℓ−ν¯
Detmold
¹
,
Lehner
²
,
Meinel
³

2015
Phys. Rev. D
256
17
418
2
View full text Add to dashboard Cite

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Status of |Vcb| and |Vub| CKM matrix elements

Cited by 11 publications

References 125 publications

Flavour Expedition to the Zeptouniverse

Flavour Expedition to the Zeptouniverse

K + → π + ν ν ¯ $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ and K L → π 0 ν ν ¯ $$ {K}_L\to {\pi}^0\nu \overline{\nu} $$ in the Standard Model: status and perspectives

Λb→pℓ−ν¯Detmold1, Lehner2, Meinel3 2015Phys. Rev. D256174182View full textAdd to dashboardCite

Contact Info

Product

Resources

About

Λb→pℓ−ν¯
Detmold
¹
,
Lehner
²
,
Meinel
³

2015
Phys. Rev. D
256
17
418
2
View full text Add to dashboard Cite