scholarly journals SUPERFICIAL NON-UNITARITY OF THE QUARK-MIXING MATRIX AS A POSSIBLE EVIDENCE FOR THE SUBSTRUCTURE OF QUARKS

1996 ◽  
Vol 11 (30) ◽  
pp. 2463-2472
Author(s):  
HIDEZUMI TERAZAWA
Keyword(s):  
Momentum Transfer ◽  
Precise Measurement ◽  
Branching Ratios ◽  
Hadronic Decays ◽  
Leptonic Decays ◽  
Quark Mixing ◽  
Composite Models ◽  
Mixing Matrix ◽  
Momentum Transfer Dependence

Superficial non-unitarity of the quark-mixing matrix, which has been predicted to be momentum transfer dependent due to the possible substructure of quarks, is discussed in composite models of quarks and leptons. A precise measurement of the momentum transfer dependence of the branching ratios for inclusive hadronic decays of τ→vτ+ hadrons and for inclusive semi-leptonic decays of K, D, B and [Formula: see text] hadrons is proposed as one of the best experimental searches for a possible evidence of the substructure of quarks.

scholarly journals Current and future neutrino oscillation constraints on leptonic unitarity

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Sebastian A. R. Ellis ◽  
Kevin J. Kelly ◽  
Shirley Weishi Li
Keyword(s):  
Precise Measurement ◽  
Sterile Neutrino ◽  
Current Knowledge ◽  
Unknown Origin ◽  
Neutrino Masses ◽  
Matrix Elements ◽  
Neutrino Mixing ◽  
Next Generation ◽  
Active Neutrino ◽  
Mixing Matrix

Abstract The unitarity of the lepton mixing matrix is a critical assumption underlying the standard neutrino-mixing paradigm. However, many models seeking to explain the as-yet-unknown origin of neutrino masses predict deviations from unitarity in the mixing of the active neutrino states. Motivated by the prospect that future experiments may provide a precise measurement of the lepton mixing matrix, we revisit current constraints on unitarity violation from oscillation measurements and project how next-generation experiments will improve our current knowledge. With the next-generation data, the normalizations of all rows and columns of the lepton mixing matrix will be constrained to ≲10% precision, with the e-row best measured at ≲1% and the τ-row worst measured at ∼10% precision. The measurements of the mixing matrix elements themselves will be improved on average by a factor of 3. We highlight the complementarity of DUNE, T2HK, JUNO, and IceCube Upgrade for these improvements, as well as the importance of ντ appearance measurements and sterile neutrino searches for tests of leptonic unitarity.

Momentum-Transfer Dependence of theLII,IIIEdge of Mg

1976 ◽  
Vol 36 (6) ◽  
pp. 326-330 ◽  
Author(s):  
Susan G. Slusky ◽  
P. C. Gibbons ◽  
S. E. Schnatterly ◽  
J. R. Fields
Keyword(s):  
Momentum Transfer ◽  
Momentum Transfer Dependence

scholarly journals Testing lepton flavour universality with (semi)-leptonic $$\varvec{D_{(s)}}$$ decays

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
Robert Fleischer ◽  
Ruben Jaarsma ◽  
Gabriël Koole
Keyword(s):  
Standard Model ◽  
Branching Ratios ◽  
Current Data ◽  
Leptonic Decays ◽  
Independent Analysis ◽  
The Standard Model ◽  
Model Independent ◽  
Pseudo Scalar ◽  
The Impact ◽  
Lepton Flavour

Abstract Data in B-meson decays indicate violations of lepton flavour universality, thereby raising the question about such phenomena in the charm sector. We perform a model-independent analysis of NP contributions in (semi)-leptonic decays of $$D_{(s)}$$D(s) mesons which originate from $$c \rightarrow d \bar{{\ell }} \nu _l$$c→dℓ¯νl and $$c \rightarrow s \bar{{\ell }} \nu _{\ell }$$c→sℓ¯νℓ charged-current interactions. Starting from the most general low-energy effective Hamiltonian containing four-fermion operators and the corresponding short-distance coefficients, we explore the impact of new (pseudo)-scalar, vector and tensor operators and constrain their effects through the interplay with current data. We pay special attention to the elements $$|V_{cd}|$$|Vcd| and $$|V_{cs}|$$|Vcs| of the Cabibbo–Kobayashi–Maskawa matrix and extract them from the $$D_{(s)}$$D(s) decays in the presence of possible NP decay contributions, comparing them with determinations utilizing unitarity. We find a picture in agreement with the Standard Model within the current uncertainties. Using the results from our analysis, we make also predictions for leptonic $$D_{(s)}^+ \rightarrow e^+ \nu _e$$D(s)+→e+νe modes which could be hugely enhanced with respect to their tiny Standard Model branching ratios. It will be interesting to apply our strategy at the future high-precision frontier.

ρ PARAMETER CONSTRAINTS ON FOURTH GENERATION QUARK MASSES

1990 ◽  
Vol 05 (10) ◽  
pp. 743-754 ◽  
Author(s):  
V. BARGER ◽  
J. L. HEWETT ◽  
T. G. RIZZO
Keyword(s):  
Fourth Generation ◽  
Quark Masses ◽  
Quark Mixing ◽  
Mixing Matrix ◽  
The Masses ◽  
Parameter Constraints

Constraints on the masses of possible fourth generation quarks (a, υ) are obtained from measurements of the ρ parameter and the elements of the quark mixing matrix. Stringent mass limits are found when the off-diagonal elements Vtυ and Vab are large. For example, with mt=90 GeV and |Vtυ|≃0.5 we find ma,v≤ 300 GeV. Stronger constraints are obtained as mt or |Vtυ| increase.

scholarly journals Constraints on the quark mixing matrix with vector-like quarks

2020 ◽  
Vol 960 ◽  
pp. 115208
Author(s):  
Drona Vatsyayan ◽  
Anirban Kundu
Keyword(s):  
Quark Mixing ◽  
Mixing Matrix
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