scholarly journals Are the CKM anomalies induced by vector-like quarks? Limits from flavor changing and Standard Model precision tests

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
B. Belfatto ◽  
Z. Berezhiani
Keyword(s):  
Standard Model ◽  
Decay Rate ◽  
Hadronic Decay ◽  
Kaon Decays ◽  
Parameter Spaces ◽  
Ckm Matrix ◽  
Flavor Changing ◽  
Beta Decays ◽  
Weak Doublet

Abstract Recent high precision determinations of Vus and Vud indicate towards anomalies in the first row of the CKM matrix. Namely, determination of Vud from beta decays and of Vus from kaon decays imply a violation of first row unitarity at about 3σ level. Moreover, there is tension between determinations of Vus obtained from leptonic Kμ2 and semileptonic Kℓ3 kaon decays. These discrepancies can be explained if there exist extra vector-like quarks at the TeV scale, which have large enough mixings with the lighter quarks. In particular, extra vector-like weak singlets quarks can be thought as a solution to the CKM unitarity problem and an extra vector-like weak doublet can in principle resolve all tensions. The implications of this kind of mixings are examined against the flavour changing phenomena and SM precision tests. We consider separately the effects of an extra down-type isosinglet, up-type isosinglet and an isodoublet containing extra quarks of both up and down type, and determine available parameter spaces for each case. We find that the experimental constraints on flavor changing phenomena become more stringent with larger masses, so that the extra species should have masses no more than few TeV. Moreover, only one type of extra multiplet cannot entirely explain all the discrepancies, and some their combination is required, e.g. two species of isodoublet, or one isodoublet and one (up or down type) isosinglet. We show that these scenarios are testable with future experiments. Namely, if extra vector-like quarks are responsible for CKM anomalies, then at least one of them should be found at scale of few TeV, and anomalous weak isospin violating Z-boson couplings with light quarks should be detected if the experimental precision on Z hadronic decay rate is improved by a factor of 2 or so.

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|.

STATUS OF STANDARD MODEL PARAMETERS

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 25-40
Author(s):  
ANTHONY R. BARKER
Keyword(s):  
Standard Model ◽  
Experimental Methods ◽  
Model Parameters ◽  
Ckm Matrix ◽  
Precision Determination ◽  
The Standard Model ◽  
Electroweak Sector

Recent experimental progress in determining the parameters of the electroweak sector of the Standard Model is summarized. The principal topics addressed include the precision determination of electroweak parameters using LEP and SLD data at the Z0 pole, measurements of the W mass by LEP-II, CDF, and D0, and determination of the elements of the CKM matrix using a variety of experimental methods.

DETERMINATION OF |Vub| FROM TAGGED AND UNTAGGED $B \overline{B}$ EVENTS WITH THE BABAR DETECTOR

2005 ◽  
Vol 20 (16) ◽  
pp. 3707-3711
Author(s):  
◽  
JOCHEN DINGFELDER
Keyword(s):  
Matrix Element ◽  
Decay Rate ◽  
B Meson ◽  
Theoretical Models ◽  
Branching Ratios ◽  
High Signal ◽  
B Meson Decays ◽  
Ckm Matrix ◽  
Babar Detector

Measurements of charmless semileptonic B-meson decays and the CKM matrix element |Vub| are reported based on a sample of 88 million [Formula: see text] events recorded with the BABAR detector. Decays B → Xuℓν are selected from both tagged and untagged [Formula: see text] events and separated from the dominant charm background, B → Xcℓν, using different kinematic variables: the lepton momentum Eℓ, the squared four-momentum transfer q2, and the hadronic mass mX. The extrapolation to the total decay rate to determine |Vub| is performed for different theoretical models. We have also measured branching ratios for the exclusive semileptonic decays B → π(ρ,ω,η,η′,a0)ℓν, where a high signal purity is reached by fully or partially reconstructing the second B meson.

scholarly journals Developments in Rare Kaon Decay Physics

2000 ◽  
Vol 50 (1) ◽  
pp. 249-297 ◽  
Author(s):  
A.R. Barker ◽  
S.H. Kettell
Keyword(s):  
Standard Model ◽  
New Physics ◽  
High Mass ◽  
Current Status ◽  
Model Parameters ◽  
Beyond The Standard Model ◽  
Kaon Decay ◽  
Kaon Decays ◽  
The Standard Model

▪ Abstract  We review the current status of the field of rare kaon decays. The study of rare kaon decays has played a key role in the development of the standard model, and the field continues to have significant impact. The two areas of greatest import are the search for physics beyond the standard model and the determination of fundamental standard-model parameters. Due to the exquisite sensitivity of rare kaon decay experiments, searches for new physics can probe very high mass scales. Studies of the K → π ν[Formula: see text] modes in particular, where the first event has recently been seen, will permit tests of the standard-model picture of quark mixing and CP violation.

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 Bs → Kℓv form factors with 2+1 flavors

2018 ◽  
Vol 175 ◽  
pp. 13008 ◽  
Author(s):  
Yuzhi Liu ◽  
Jon A. Bailey ◽  
A. Bazavov ◽  
C. Bernard ◽  
C. M. Bouchard ◽  
...  
Keyword(s):  
Quark Mass ◽  
Strange Quark ◽  
Lattice Spacing ◽  
Light Quark ◽  
Form Factors ◽  
Ckm Matrix ◽  
Strange Quark Mass ◽  
Light Quark Mass ◽  
B Quark

Using the MILC 2+1 flavor asqtad quark action ensembles, we are calculating the form factors f0 and f+ for the semileptonic Bs → Kℓv decay. A total of six ensembles with lattice spacing from ≈ 0.12 to 0.06 fm are being used. At the coarsest and finest lattice spacings, the light quark mass m’l is one-tenth the strange quark mass m’s. At the intermediate lattice spacing, the ratio m’l/m’s ranges from 0.05 to 0.2. The valence b quark is treated using the Sheikholeslami-Wohlert Wilson-clover action with the Fermilab interpretation. The other valence quarks use the asqtad action. When combined with (future) measurements from the LHCb and Belle II experiments, these calculations will provide an alternate determination of the CKM matrix element |Vub|.

scholarly journals Multimessenger Probes for New Physics in Light of A. Sakharov’s Legacy in Cosmoparticle Physics

Universe ◽  
2021 ◽  
Vol 7 (7) ◽  
pp. 222
Author(s):  
Maxim Khlopov
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
New Physics ◽  
Physical Models ◽  
Beyond The Standard Model ◽  
Fundamental Relationship ◽  
Relationship Of ◽  
The Universe ◽  
Selection Of

A.D. Sakharov’s legacy in now standard model of the Universe is not reduced to baryosynthesis but extends to the foundation of cosmoparticle physics, which studies the fundamental relationship of cosmology and particle physics. Development of cosmoparticle physics involves cross-disciplinary physical, astrophysical and cosmological studies of physics Beyond the Standard model (BSM) of elementary particles. To probe physical models for inflation, baryosynthesis and dark matter cosmoparticle physics pays special attention to model dependent messengers of the corresponding models, making their tests possible. Positive evidence for such exotic phenomena as nuclear interacting dark atoms, primordial black holes or antimatter globular cluster in our galaxy would provide the selection of viable BSM models determination of their parameters.

scholarly journals THE DUALIZED STANDARD MODEL AND ITS APPLICATIONS — AN INTERIM REPORT

1999 ◽  
Vol 14 (14) ◽  
pp. 2173-2203 ◽  
Author(s):  
HONG-MO CHAN ◽  
SHEUNG TSUN TSOU
Keyword(s):  
Standard Model ◽  
High Energy ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Matrix Elements ◽  
Ckm Matrix ◽  
High Energy Cosmic Rays ◽  
Perturbative Method ◽  
Ckm Matrix Elements ◽  
Physical Consequences

Based on a non-Abelian generalization of electric–magnetic duality, the Dualized Standard Model (DSM) suggests a natural explanation for exactly three generations of fermions as the "dual colour" [Formula: see text] symmetry broken in a particular manner. The resulting scheme then offers on the one hand a fermion mass hierarchy and a perturbative method for calculating the mass and mixing parameters of the Standard Model fermions, and on the other hand testable predictions for new phenomena ranging from rare meson decays to ultra-high energy cosmic rays. Calculations to one-loop order gives, at the cost of adjusting only three real parameters, values for the following quantities all (except one) in very good agreement with experiment: the quark CKM matrix elements ‖Vrs‖, the lepton CKM matrix elements ‖Urs‖, and the second generation masses mc, ms, mμ. This means, in particular, that it gives near maximal mixing Uμ3 between νμ and ντ as observed by SuperKamiokande, Kamiokande and Soudan, while keeping small the corresponding quark angles Vcb, Vts. In addition, the scheme gives (i) rough order-of-magnitude estimates for the masses of the lowest generation, (ii) predictions for low energy FCNC effects such as KL→ eμ, and (iii) a possible explanation for the long-standing puzzle of air showers beyond the GZK cut-off. All these together, however, still represent but a portion of the possible physical consequences derivable from the DSM scheme, the majority of which are yet to be explored.

scholarly journals Direct CP violation and the ΔI = 1/2 rule in K → ππ decay in the Standard Model

2022 ◽  
Vol 258 ◽  
pp. 01003
Author(s):  
Christopher Kelly
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Systematic Error ◽  
Error Estimates ◽  
Lattice Calculation ◽  
Kaon Decays ◽  
The Standard Model

We discuss the RBC & UKQCD collaborations’ recent [1] lattice calculation of ϵ′, the measure of direct CP-violation in kaon decays. This result significantly improves on our previous 2015 calculation, with nearly 4× the statistics and more reliable systematic error estimates. We discuss how our results demonstrate the Standard Model origin of the ΔI = 1/2 rule, and present our plans for future calculations.

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