Study of the semileptonic Bc → ηcτ−v̄τ decay in W′ model

2021 ◽  
Author(s):  
S. Mahata ◽  
P. Maji ◽  
S. Biswas ◽  
S. Sahoo
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
New Physics ◽  
Experimental Results ◽  
Lepton Flavor ◽  
The Standard Model ◽  
Text Model

Recently, many discrepancies between the Standard Model (SM) predictions and experimental results have been found in [Formula: see text] quark transitions. Motivated by these discrepancies, we investigated the semileptonic [Formula: see text] decay in [Formula: see text] model. In this paper, we have estimated different decay observables such as branching ratio, lepton flavor universality (LFU) ratio [Formula: see text] and forward–backward asymmetry in the SM as well as in the [Formula: see text] model. In [Formula: see text] model, we find significant deviations from the SM for the observables except for the forward–backward asymmetry. This deviation gives us a possible indication of new physics (NP).

Unparticle effects on B → D(∗)τν

2019 ◽  
Vol 34 (19) ◽  
pp. 1950149
Author(s):  
Jong-Phil Lee
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
New Physics ◽  
Experimental Results ◽  
The Standard Model ◽  
Best Fit

We examine the possible unparticle effects on [Formula: see text] associated with [Formula: see text] decays by minimum-[Formula: see text] fitting. Recent measurements from Belle and LHCb are included in this analysis. While it is true that the new experimental results of [Formula: see text] get closer to the Standard Model (SM) predictions, there is still room for new physics and unparticles are also one possibility. Our best-fit values are [Formula: see text] and [Formula: see text], which are still far from the SM values by more than [Formula: see text] or almost [Formula: see text] [Formula: see text]. We also find that the unparticle effects are quite safe to render the branching ratio [Formula: see text] less than 10%.

Lepton flavor violating decays in model

2019 ◽  
Vol 97 (12) ◽  
pp. 1270-1276
Author(s):  
P. Nayek ◽  
P. Maji ◽  
S. Sahoo
Keyword(s):  
Standard Model ◽  
Neutral Current ◽  
Branching Ratios ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Lepton Flavor ◽  
Flavor Changing ◽  
The Standard Model ◽  
Flavor Changing Neutral Current ◽  
Text Model

Motivated by the hints of lepton flavor violating (LFV) decays, we study Bd,s → μτ, Bs,d → τe, and τ– → e– + e+ + e– decays in [Formula: see text] model. These LFV decays present interesting patterns that may reveal the shape of new physics beyond the standard model. Considering the effect of both Z- and [Formula: see text]-mediated flavor-changing neutral current we calculate the branching ratios for these decays. We find the branching ratios [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text].

scholarly journals Study of the rare decays Bs,d∗→ l+l− in Z′ model

2017 ◽  
Vol 32 (14) ◽  
pp. 1750075 ◽  
Author(s):  
Debika Banerjee ◽  
Priya Maji ◽  
Sukadev Sahoo
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Rare Decays ◽  
Branching Ratio ◽  
Branching Ratios ◽  
New Physics ◽  
Leptonic Decays ◽  
The Standard Model ◽  
Text Model ◽  
Vector Formula

The rare decays [Formula: see text] are important to probe the flavor sector of the standard model and to search new physics beyond the SM. Unlike pseudoscalar [Formula: see text] meson, the leptonic decays of vector [Formula: see text] mesons are not chirally suppressed which compensates for their short lifetimes, and results in significant branching ratios. In this paper, we estimate the branching ratios of [Formula: see text][Formula: see text] rare decays in [Formula: see text] model which is an extension of the SM with an extra [Formula: see text] gauge symmetry. We find that the branching ratios are increased from their corresponding standard model values and vary with the mass of [Formula: see text] boson. The lower the mass of [Formula: see text] boson, the higher is the branching ratio.

scholarly journals Disentangling QCD and new physics in D → πℓ+ℓ−

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Aoife Bharucha ◽  
Diogo Boito ◽  
Cédric Méaux
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
Branching Ratios ◽  
New Physics ◽  
Operator Product ◽  
Beyond The Standard Model ◽  
Spectral Functions ◽  
The Standard Model ◽  
Model Independent ◽  
Weak Annihilation

Abstract In this paper we consider the decay D+ → π+ℓ+ℓ−, addressing in particular the resonance contributions as well as the relatively large contributions from the weak annihilation diagrams. For the weak annihilation diagrams we include known results from QCD factorisation at low q2 and at high q2, adapting the existing calculation for B decays in the Operator Product Expansion. The hadronic resonance contributions are obtained through a dispersion relation, modelling the spectral functions as towers of Regge-like resonances in each channel, as suggested by Shifman, imposing the partonic behaviour in the deep Euclidean. The parameters of the model are extracted using e+e− → (hadrons) and τ → (hadrons) + ντ data as well as the branching ratios for the resonant decays D+ → π+R(R → ℓ+ℓ−), with R = ρ, ω, and ϕ. We perform a thorough error analysis, and present our results for the Standard Model differential branching ratio as a function of q2. Focusing then on the observables FH and AFB, we consider the sensitivity of this channel to effects of physics beyond the Standard Model, both in a model independent way and for the case of leptoquarks.

scholarly journals Searching for new physics in charm radiative decays

2018 ◽  
Vol 33 (32) ◽  
pp. 1850194
Author(s):  
Aritra Biswas ◽  
Sanjoy Mandal ◽  
Nita Sinha
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
New Physics ◽  
Radiative Decays ◽  
Symmetric Model ◽  
Leading Order ◽  
Photon Polarization ◽  
Long Distance ◽  
The Standard Model ◽  
Distance Effects

We show that for a heavy vector-like quark model with a down type isosinglet, branching ratio for [Formula: see text] decay is enhanced by more than [Formula: see text] as compared to that in the Standard model when QCD corrections to next-to-leading order are incorporated. In a left–right symmetric model (LRSM) along with a heavy vector-like fermion, enhancement of this order can be achieved at the bare (QCD uncorrected) level itself. We propose that a measurement of the photon polarization could be used to signal the presence of such new physics in spite of the large long distance effects. We find that there is a large region within the allowed parameter space of the model with a vector-like quark and an additional left–right symmetry, where, the photon polarization can be dominantly right-handed.

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 Status of the NA62 Experiment

2020 ◽  
Vol 234 ◽  
pp. 01012
Author(s):  
M. Piccini
Keyword(s):  
Data Analysis ◽  
Standard Model ◽  
Indirect Effects ◽  
Branching Ratio ◽  
New Physics ◽  
Single Event ◽  
Model Framework ◽  
The Standard Model ◽  
Better Than

The decay $ {K^ + } \to {\pi ^ + }v\bar v $, with a very precisely predicted branching ratio of less than 10−10 in the Standard Model framework, is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at CERN SPS is designed to measure the branching ratio of such decay with a decay-in-flight technique, novel for this channel. The main goal of NA62 is to measure such Branching Ratio of $ {K^ + } \to {\pi ^ + }v\bar v $ with an accuracy better than 20%. This will be achieved by collecting up to 100 $ {K^ + } \to {\pi ^ + }v\bar v $ events with a background contamination at the level of 10%. The NA62 detector was commissioned in 2014 and 2015 and the experiment took physics data from 2015 to 2018. NA62 has already published the result of the 2016 data analysis. The 2017 data analysis is in progress, the single event sensitivity reached and the evaluation of the main backgrounds will be shown in this contribution.

scholarly journals Recent Measurements of CP-Violation at the B-Factories

2003 ◽  
Vol 18 (30) ◽  
pp. 2083-2098
Author(s):  
Gabriella Sciolla
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
New Physics ◽  
Experimental Results ◽  
Time Dependent ◽  
The Standard Model ◽  
Substantial Progress ◽  
Cp Asymmetries

Recent measurements of time-dependent CP-asymmetries at the B-factories have led to substantial progress in our understanding of CP-violation. In this paper, we review some of these experimental results and discuss their implications in the Standard Model and their sensitivity to New Physics.

scholarly journals Leptoquarks in Flavour Physics

2018 ◽  
Vol 179 ◽  
pp. 01015 ◽  
Author(s):  
Dario Müller
Keyword(s):  
Standard Model ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Z Boson ◽  
New Physics ◽  
Experimental Results ◽  
The Standard Model ◽  
Z Boson Decays ◽  
Flavour Physics ◽  
Lepton Flavour

While the LHC has not directly observed any new particle so far, experimental results from LHCb, BELLE and BABAR point towards the violation of lepton flavour universality in b ⟶ sℓ+ and b ⟶ c-ℓν. In this context, also the discrepancy in the anomalous magnetic moment of the muon can be interpreted as a sign of lepton flavour universality violation. Here we discuss how these hints for new physics can also be explained by introducing leptoquarks as an extension of the Standard Model. Indeed, leptoquarks are good candidates to explain the anomaly in the anomalous magnetic moment of the muon because of an mg/mμ enhanced contribution giving correlated effects in Z boson decays which is particularly interesting in the light of future precision experiments.

scholarly journals Probing new physics with $B^0_s\to\mu^+\mu^-$: Status and perspectives

2014 ◽  
Vol 29 (21) ◽  
pp. 1444004 ◽  
Author(s):  
Robert Fleischer
Keyword(s):  
Standard Model ◽  
Decay Width ◽  
Rare Decay ◽  
Branching Ratio ◽  
New Physics ◽  
High Luminosity ◽  
Width Difference ◽  
Rate Asymmetry ◽  
The Standard Model ◽  
Meson System

The rare decay [Formula: see text] plays a key role for the testing of the Standard Model. It is pointed out that the sizable decay width difference ΔΓsof the Bs-meson system affects this channel in a subtle way. As a consequence, its calculated Standard Model branching ratio has to be upscaled by about 10%. Moreover, the sizable ΔΓsmakes a new observable through the effective [Formula: see text] lifetime accessible, which probes New Physics in a way complementary to the branching ratio and adds an exciting new topic to the agenda for the high-luminosity upgrade of the LHC. Further probes of New Physics are offered by a CP-violating rate asymmetry. Correlations between these observables and the [Formula: see text] branching ratio are illustrated for specific models of New Physics.

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