scholarly journals Experimental status of LNU in B decays in LHCb

2019 ◽  
Author(s):  
Sean Benson
Keyword(s):  
Standard Model ◽  
Semileptonic Decays ◽  
Experimental Tests ◽  
New Physics ◽  
B Decays ◽  
Experimental Status ◽  
Lepton Universality ◽  
Highly Sensitive ◽  
The Standard Model ◽  
Charged Leptons

In the Standard Model, the three charged leptons are identical copies of each other, apart from mass differences. Experimental tests of this feature in semileptonic decays of -hadrons are highly sensitive to New Physics particles which preferentially couple to the 2nd and 3rd generations of leptons. A review of the latest lepton universality tests in semileptonic transitions at is reported.

scholarly journals Experimental Review on Lepton Universality and Lepton Flavour Violation tests in B decays

2020 ◽  
Vol 234 ◽  
pp. 01004 ◽  
Author(s):  
P. de Simone
Keyword(s):  
Standard Model ◽  
Theoretical Models ◽  
New Physics ◽  
B Decays ◽  
Experimental Status ◽  
Lepton Flavour Violation ◽  
Lepton Universality ◽  
The Standard Model ◽  
Flavour Violation ◽  
Lepton Flavour

Tests of lepton flavour universality in B decays offer an excellent opportunity to test the Standard Model, and show hints of new physics in analyses performed by the LHCb, Belle and BaBar experiments. Several theoretical models proposed to explain possible violation of lepton flavour universality claim a connection with lepton flavour violation in B decays. These proceedings review the experimental status of the tests of lepton flavour universality and the searches of lepton flavour violation in B decays.

scholarly journals BRIEF REVIEW OF THE SEARCHES FOR THE RARE DECAYS $B^0_{s}\to\mu^+\mu^-$ and $B^0\to\mu^+\mu^-$

2012 ◽  
Vol 27 (27) ◽  
pp. 1230028 ◽  
Author(s):  
JOHANNES ALBRECHT
Keyword(s):  
Standard Model ◽  
Rare Decays ◽  
Branching Fractions ◽  
New Physics ◽  
Exclusion Limit ◽  
Experimental Status ◽  
Highly Sensitive ◽  
The Standard Model

The current experimental status of the searches for the very rare decays [Formula: see text] and [Formula: see text] is discussed. These channels are highly sensitive to various extensions of the Standard Model, especially in the scalar and pseudoscalar sector. The recent, most sensitive measurements from the CDF, ATLAS, CMS and LHCb collaborations are discussed and the combined upper exclusion limit on the branching fractions determined by the LHC experiments is shown to be 4.2×10-9 for [Formula: see text] and 0.8×10-9 for [Formula: see text]. The implications of these tight bounds on a selected set of New Physics models is sketched.

scholarly journals Probing lepton universality with (semi)-leptonic B decays

2019 ◽  
Author(s):  
Giovanni Banelli ◽  
Robert Fleischer ◽  
Ruben Jaarsma ◽  
Gilberto Tetlalmatzi-Xolocotzi
Keyword(s):  
Standard Model ◽  
Branching Fraction ◽  
Branching Fractions ◽  
Belle Collaboration ◽  
New Physics ◽  
Recent Measurement ◽  
Beyond The Standard Model ◽  
Lepton Universality ◽  
Highly Sensitive ◽  
The Standard Model

The most recent measurements of the observables R_{D^{(*)}}RD(*) are in tension with the Standard Model offering hints of New Physics in b\rightarrow c \ell \bar{\nu}_{\ell}b→cℓν‾ℓ transitions. Motivated by these results, in this work we present an analysis on their b\rightarrow u \ell \bar{\nu}_{\ell}b→uℓν‾ℓ counterparts (for \ell=e, ~\mu, ~\tauℓ=e,μ,τ). Our study has three main objectives. Firstly, using ratios of branching fractions, we assess the effects of beyond the Standard Model scalar and pseudoscalar particles in leptonic and semileptonic BB decays (B^-\rightarrow \ell^- \bar{\nu}_{\ell}B−→ℓ−ν‾ℓ, \bar{B}\rightarrow \pi \ell \bar{\nu}_{\ell}B‾→πℓν‾ℓ and \bar{B}\rightarrow \rho \ell \bar{\nu}_{\ell}B‾→ρℓν‾ℓ). Here a key role is played by the leptonic BB processes, which are highly sensitive to new pseudoscalar interactions. In particular, we take advantage of the most recent measurement of the branching fraction of the channel B^-\rightarrow \mu^-\bar{\nu}_{\mu}B−→μ−ν‾μ by the Belle collaboration. Secondly, we extract the CKM matrix element |V_{ub}||Vub| while accounting simultaneously for New Physics contributions. Finally, we provide predictions for the branching fractions of yet unmeasured leptonic and semileptonic BB decays.

scholarly journals One Loop Corrections to Decay \(\tau\rightarrow \mu\gamma\) in Economical 3-3-1 Model

2015 ◽  
Vol 25 (2) ◽  
pp. 113
Author(s):  
Truong Trong Thuc ◽  
Le Tho Hue ◽  
Dinh Phan Khoi ◽  
Nguyen Thanh Phong
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Lepton Flavor ◽  
Unitary Gauge ◽  
The Standard Model ◽  
Charged Leptons

Lepton flavor violating (cLFV) decays of charged leptons such as \(\tau\rightarrow \mu\gamma\), \(\tau\rightarrow e\gamma\), \(\mu\rightarrow e\gamma\),..., are now the subjects of experiments as signals of new Physics beyond the Standard Model (SM). In the limit of the unitary gauge, we prove that contributions from one loop corrections to the above decays are very small in the framework of the economical 3-3-1 model.

scholarly journals Charming loops in exclusive rare FCNC B-decays

2019 ◽  
Vol 222 ◽  
pp. 01007 ◽  
Author(s):  
Dmitri Melikhov
Keyword(s):  
Standard Model ◽  
Gain Control ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Reliable Control ◽  
B Decays ◽  
Flavour Changing Neutral Currents ◽  
Neutral Currents ◽  
The Standard Model ◽  
Theoretical Predictions

Rare B-decays induced by flavour-changing neutral currents (FCNC) is one of the promising candidates for probing physics beyond the Standard model. However, for identifying potential new physics from the data, reliable control over QCD contributions is necessary. We focus on one of such QCD contributions – the charming loops – that potentially can lead to difficulties in disentangling new physics effects from the observable and discuss the possibility to gain control over theoretical predictions for charming loops.

RARE B AND τ DECAYS AND SEARCHES FOR NEW PHYSICS

2007 ◽  
Vol 22 (30) ◽  
pp. 5433-5442
Author(s):  
R. J. BARLOW
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Excellent Agreement ◽  
Rare Decays ◽  
B Mesons ◽  
New Physics ◽  
B Decays ◽  
The Standard Model ◽  
Model Predictions ◽  
Vector Particles

New results on rare decays of B mesons and τ leptons are summarised. Measurement are generally in excellent agreement with the Standard Model predictions, the only exceptions being the polarisation of vector particles in B decays and the non-appearance of CP violation in B ± → K ±π0.

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 PROBE THE EFFECTS OF SPLIT SUSY IN RARE B DECAYS

2006 ◽  
Vol 21 (14) ◽  
pp. 1137-1150 ◽  
Author(s):  
CHUAN-HUNG CHEN ◽  
CHAO-QIANG GENG
Keyword(s):  
Standard Model ◽  
Parity Violation ◽  
Branching Ratio ◽  
New Physics ◽  
B Decays ◽  
The Standard Model ◽  
Order Of Magnitude ◽  
Physics Model ◽  
Split Supersymmetry ◽  
New Interactions

We study the decays of B→K(*)ℓ+ℓ- in split supersymmetry with R-parity violation. We find that the decay branching ratio of B→Kτ+τ- in the new physics model due to the scalar interactions can be 1.8×10-6 which is about one order of magnitude larger than in the standard model, whereas those of B→Kℓ+ℓ- (ℓ=e and μ) and the K* modes are insensitive to the new physics. On the other hand, the forward–backward asymmetries of B→Kτ+τ- and Kμ+μ-, vanishing in the standard model, can be over 10 and 1%, respectively. In addition, we show that the new interactions will significantly change the forward–backward asymmetry in B→K*τ+τ-.

scholarly journals THEORY OF CP VIOLATION IN THE B-MESON SYSTEM

2002 ◽  
Vol 17 (22) ◽  
pp. 2936-2950 ◽  
Author(s):  
MATTHIAS NEUBERT
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
B Meson ◽  
New Physics ◽  
B Decays ◽  
The Standard Model ◽  
Recent Developments ◽  
Meson System

Recent developments in the theory of CP violation in the B-meson system are reviewed, with focus on the determination of sin 2β from B → J/ψ K decays, its implications for tests of the Standard Model and searches for New Physics, and the determination of γ and α from charmless hadronic B decays.

scholarly journals RECENT BABAR RESULTS ON B DECAYS

2008 ◽  
Vol 23 (21) ◽  
pp. 3218-3223
Author(s):  
◽  
P. J. CLARK
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Hadronic Decays ◽  
B Decays ◽  
The Standard Model ◽  
Babar Experiment

Several recent key results from the BABAR experiment are presented, most using 383.6 fb−1 of data. In particular, the search for B+ → τ+ν, inclusive and exclusive measurements of |Vub|, measurements of b → dγ decays and new observations of rare charmless hadronic decays. The new results provide important experimental constraints on the Standard Model and new physics models.

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