Exclusive Semi-leptonic Decays b → s ( d )νν̄ in the Standard Model with Fourth Generation

2012 ◽  
Vol 57 (2) ◽  
pp. 245-250 ◽  
Author(s):  
Jiao Zhang ◽  
Chong-Xing Yue ◽  
Bin Guo ◽  
Xu-Xin Li
Keyword(s):  
Standard Model ◽  
Fourth Generation ◽  
Leptonic Decays ◽  
The Standard Model

scholarly journals Long-distance QCD effects in FCNC B → γl+l- decays

2018 ◽  
Vol 192 ◽  
pp. 00031 ◽  
Author(s):  
Anastasiia Kozachuk ◽  
Dmitri Melikhov ◽  
Nikolai Nikitin
Keyword(s):  
Standard Model ◽  
Recent Work ◽  
Flavour Changing Neutral Currents ◽  
Neutral Currents ◽  
Long Distance ◽  
Leptonic Decays ◽  
The Standard Model

This presentation reviews the main results of our recent work [1] on rare radiative leptonic decays Bd,s → γμ+μ- and Bd,s → γe+e- induced by flavour-changing neutral currents (FCNC) in the Standard Model.

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.

scholarly journals MEASUREMENT OF THE RATIO OF THE CHARGED KAON LEPTONIC DECAYS AT NA62

2014 ◽  
Vol 35 ◽  
pp. 1460436
Author(s):  
VENELIN KOZHUHAROV
Keyword(s):  
Data Analysis ◽  
Standard Model ◽  
Weak Interactions ◽  
New Physics ◽  
Charged Kaon ◽  
Kaon Decays ◽  
Leptonic Decays ◽  
Lepton Universality ◽  
Analysis Technique ◽  
The Standard Model

The ratio of the leptonic charged kaon decays RK = Γ(K± → e±ν)/Γ(K± → μ±ν) is sensitive to the structure of the weak interactions and can be precisely calculated within the Standard Model. Presence of New Physics can introduce a shift on its value of the order of a percent. The NA62 experiment at CERN SPS used data from a dedicated run in 2007 to perform a measurement of this ratio and probe the lepton universality. The data analysis technique and the final results are presented.

scholarly journals Searching for new physics in semi-leptonic baryon decays

2017 ◽  
Vol 32 (08) ◽  
pp. 1750043 ◽  
Author(s):  
E. Di Salvo ◽  
Z. J. Ajaltouni
Keyword(s):  
Standard Model ◽  
Decay Width ◽  
Form Factors ◽  
New Physics ◽  
Scalar Coupling ◽  
Partial Decay Width ◽  
Beyond The Standard Model ◽  
Leptonic Decays ◽  
The Standard Model ◽  
Pseudo Scalar

We propose two different and complementary observables for singling out possible signals of physics beyond the Standard Model (SM) in the semi-leptonic decays [Formula: see text], both with the [Formula: see text] lepton and with a light lepton. The two observables are the partial decay width and a T-odd asymmetry, whose respective sensitivities to scalar and/or pseudo-scalar coupling are calculated as functions of the parameters characterizing new physics (NP). Two different form factors are used. Three particular cases are discussed and analyzed in detail.

scholarly journals PROSPECTS FOR KLOE-2

2011 ◽  
Vol 26 (03n04) ◽  
pp. 529-532
Author(s):  
◽  
PAWEŁ MOSKAL
Keyword(s):  
Quantum Mechanics ◽  
Standard Model ◽  
Ground State ◽  
Neutral Kaon ◽  
Beyond The Standard Model ◽  
Fundamental Symmetries ◽  
Leptonic Decays ◽  
Electron Positron ◽  
The Standard Model

The basic motivation of the KLOE-2 experiment is the test of fundamental symmetries and Quantum Mechanics coherence of the neutral kaon system, and the search for phenomena beyond the Standard Model in the hadronic and leptonic decays of ground-state mesons. Perspectives for experimentation by means of the KLOE-2 apparatus equipped with the inner tracker, new scintillation calorimeters, and the γγ taggers at the DAΦNE electron-positron collider upgraded in luminosity and energy are presented.

scholarly journals Constraints on a Fourth Generation of Fermions from Higgs Boson Searches

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Alexander Lenz
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Higgs Doublet ◽  
Current Status ◽  
Fourth Generation ◽  
The Past ◽  
The Standard Model

We review the past and current status of the extension of the standard model (SM) by a fourth generation of fermions. In particular the new results for Higgs boson searches at the LHC and at Tevatron exclude the possibility of having simply a perturbative fourth generation of fermions with one Higgs doublet (SM4). We also briefly mention more complicated extensions of the SM4, which are not yet excluded, like adding in addition another Higgs doublet to the SM4.

scholarly journals COMPLETE STUDY OF THE SEMILEPTONIC B TO $K_2^*(1430)$ DECAYS IN THE STANDARD MODEL WITH FOURTH GENERATION

2012 ◽  
Vol 27 (25) ◽  
pp. 1250149 ◽  
Author(s):  
MUHAMMAD JUNAID ◽  
MUHAMMAD JAMIL ASLAM ◽  
ISHTIAQ AHMED
Keyword(s):  
Standard Model ◽  
Form Factors ◽  
Experimental Information ◽  
Fourth Generation ◽  
Final State ◽  
Cp Asymmetry ◽  
The Standard Model ◽  
Complete Study ◽  
Lepton Polarization ◽  
State Formula

The [Formula: see text] decays are analyzed in the standard model (SM) extended to fourth generation of quarks (SM4). The decay rate, forward–backward asymmetry, lepton polarization asymmetries, the helicity fractions of the final state [Formula: see text] meson and CP asymmetry are discussed using the form factors calculated in the light-cone sum rules (LCSR) approach. We utilized the constraints on different fourth generation parameters obtained from the experimental information on K, B and D decays and from their recent searches at the ATLAS and CMS experiments to explore their impact on the [Formula: see text] decays. We find that the values of above mentioned physical observables deviate significantly from their minimal SM predications. In the present study, we will also perform the analysis of CP asymmetry in [Formula: see text] decays within SM4, which is one of the most interesting observable in the study of SM4.

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