scholarly journals A COMPARATIVE STUDY ON B →K*ℓ+ ℓ- AND $B \to K_0^\ast (1430) \ell^+ \ell^-$ DECAYS IN THE SUPERSYMMETRIC MODELS

2011 ◽  
Vol 26 (12) ◽  
pp. 901-911 ◽  
Author(s):  
V. BASHIRY ◽  
M. BAYAR ◽  
K. AZIZI
Keyword(s):  
Standard Model ◽  
Comparative Study ◽  
Scalar Meson ◽  
Branching Ratio ◽  
Mass Region ◽  
P Wave ◽  
Muon Channel ◽  
The Standard Model ◽  
Model Predictions ◽  
Supersymmetric Models

In this paper, we compare the branching ratio and rate difference of electron channel to muon channel of [Formula: see text] and B →K*ℓ+ℓ- decays, where [Formula: see text] is the p-wave scalar meson, in the supersymmetric models. MSSM with R parity is considered since considerable deviation from the standard model predictions can be obtained in B→Xs ℓ-ℓ+. Taking CQ1 and CQ2 about one which is consistent with the B→K*μ+μ- rate at low dileptonic invariant mass region (1 ≤ q2 ≤ 6 GeV 2). It is found that, firstly, the [Formula: see text] decay is measurable at LHC, secondly, in comparison with B →K*ℓ+ ℓ- decay a greater deviation in the [Formula: see text] decay can be seen. Measurement of these observables for the semileptonic rare [Formula: see text], in particular, at low q2 region can give valuable information about the nature of interactions within Standard Model or beyond.

scholarly journals Search for an LSP Gluino from Stop Decay

2001 ◽  
Vol 16 (supp01b) ◽  
pp. 804-806
Author(s):  
PATRICE VERDIER
Keyword(s):  
Standard Model ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Delphi Detector ◽  
The Standard Model ◽  
Model Predictions ◽  
Supersymmetric Models ◽  
Integrated Luminosity

In some supersymmetric models, the gluino [Formula: see text] could be light and stable, and would hadronize to form R-hadrons. Data collected by the DELPHI detector at centre-of-mass energy from 189 to 202 GeV corresponding to an integrated luminosity of 384 pb -1 have been used to search for R-hadrons from stop decay. The observed number of events is in agreement with the Standard Model predictions. Results are presented in terms of excluded regions in the plane [Formula: see text]

B anomalies with unparticles

2021 ◽  
Vol 36 (30) ◽  
Author(s):  
Jong-Phil Lee
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Branching Ratio ◽  
Branching Ratios ◽  
The Standard Model ◽  
Model Predictions ◽  
Best Fit

We analyze the [Formula: see text] anomalies associated with the [Formula: see text] decays in the unparticle model. The fraction of the branching ratios [Formula: see text] and other parameters related to the polarization are fitted to the experimental data by minimizing [Formula: see text]. The best-fit values are [Formula: see text] and [Formula: see text] which are still larger than the standard model predictions. We find that our results safely render the branching ratio [Formula: see text] below [Formula: see text].

scholarly journals Search for π0 decays to invisible particles

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
E. Cortina Gil ◽  
◽  
A. Kleimenova ◽  
E. Minucci ◽  
S. Padolski ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Branching Ratio ◽  
Standard Model Higgs Boson ◽  
Scalar Mixing ◽  
Upper Limit ◽  
Upper Limits ◽  
The Standard Model ◽  
Model Independent

Abstract The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 109 tagged π0 mesons from K+ → π+π0(γ), searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4 × 10−9 is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay K+ → π+X, where X is a particle escaping detection with mass in the range 0.110–0.155 GeV/c2 and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming X to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.

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.

A GLANCE BEYOND THE STANDARD MODEL: LATEST RESULTS FROM THE MEG EXPERIMENT

2014 ◽  
Vol 35 ◽  
pp. 1460390
Author(s):  
SIMEONE DUSSONI
Keyword(s):  
Beyond Standard Model ◽  
Standard Model ◽  
High Intensity ◽  
State Of The Art ◽  
Branching Ratio ◽  
Beyond The Standard Model ◽  
Upper Limit ◽  
The Standard Model ◽  
Key Features ◽  
Very High

The MEG experiment started taking data in 2009 looking for the Standard Model suppressed decay μ → e + γ, which, if observed, can reveal Beyond Standard Model physics. It makes use of state-of-the art detectors optimized for operating in conditions of very high intensity, rejecting as much background as possible. The data taking ended August 2013 and an upgrade R&D is started to push the experimental sensitivity. The present upper limit on the decay Branching Ratio (BR) is presented, obtained with the subset of data from 2009 to 2011 run, together with a description of the key features of the upgraded detector.

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).

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.

CP VIOLATION IN THE B SYSTEM—A STATISTICAL ANALYSIS

1990 ◽  
Vol 05 (05) ◽  
pp. 337-347
Author(s):  
DAVID LONDON
Keyword(s):  
Statistical Analysis ◽  
Cp Violation ◽  
Standard Model ◽  
Probability Distributions ◽  
New Physics ◽  
Hadronic Decay ◽  
System A ◽  
The Standard Model ◽  
Model Predictions ◽  
Cp Asymmetries

The standard model predictions for CP violating hadronic decay asymmetries are presented in the form of probability distributions. From these distributions, it can be easily seen what the most likely values of these quantities are, which measurements would clearly be signs of new physics, and which values of the CP asymmetries would most constrain the parameters of the standard model.

scholarly journals Higgs boson production cross-section measurements and their EFT interpretation in the $$4\ell $$ decay channel at $$\sqrt{s}=$$13 TeV with the ATLAS detector

2020 ◽  
Vol 80 (10) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Cross Section ◽  
Decay Channel ◽  
Branching Ratio ◽  
Proton Collision ◽  
Boson Production ◽  
Theory Approach ◽  
Higgs Boson Production ◽  
The Standard Model

AbstractHiggs boson properties are studied in the four-lepton decay channel (where lepton = e, $$\mu $$ μ ) using 139 $$\hbox {fb}^{-1}$$ fb - 1 of proton–proton collision data recorded at $$\sqrt{s}=$$ s = 13 TeV by the ATLAS experiment at the Large Hadron Collider. The inclusive cross-section times branching ratio for $$H\rightarrow ZZ^*$$ H → Z Z ∗ decay is measured to be $$1.34 \pm 0.12$$ 1.34 ± 0.12  pb for a Higgs boson with absolute rapidity below 2.5, in good agreement with the Standard Model prediction of $$1.33 \pm 0.08$$ 1.33 ± 0.08  pb. Cross-sections times branching ratio are measured for the main Higgs boson production modes in several exclusive phase-space regions. The measurements are interpreted in terms of coupling modifiers and of the tensor structure of Higgs boson interactions using an effective field theory approach. Exclusion limits are set on the CP-even and CP-odd ‘beyond the Standard Model’ couplings of the Higgs boson to vector bosons, gluons and top quarks.

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