scholarly journals Measurement of the branching ratios for the standard model Higgs decays into muon pairs and into Z boson pairs at a 1.4 TeV CLIC

2016 ◽  
Author(s):  
Keyword(s):  
Standard Model ◽  
Z Boson ◽  
Branching Ratios ◽  
Muon Pairs ◽  
The Standard Model

scholarly journals THE LEPTON FLAVOR VIOLATING DECAYS Z→li lj IN THE SIMPLEST LITTLE HIGGS MODEL

2012 ◽  
Vol 27 (28) ◽  
pp. 1250158 ◽  
Author(s):  
XIAO-FANG HAN ◽  
LEI WANG
Keyword(s):  
Standard Model ◽  
Z Boson ◽  
Branching Ratios ◽  
Higgs Model ◽  
Little Higgs ◽  
Decay Modes ◽  
Lepton Flavor ◽  
Loop Level ◽  
Flavor Changing ◽  
The Standard Model

In the simplest little Higgs model the new flavor-changing interactions between heavy neutrinos and the Standard Model leptons can generate contributions to some lepton flavor violating decays of Z-boson at one-loop level, such as Z→τ±μ∓, Z→τ±e∓ and Z→μ±e∓. We examine the decay modes and find that the branching ratios can reach 10-7 for the three decays, which should be accessible at the GigaZ option of the ILC.

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.

TeV Scale B – L Phenomenology at LHC

2007 ◽  
Vol 22 (31) ◽  
pp. 5889-5908 ◽  
Author(s):  
M. Abbas ◽  
W. Emam ◽  
S. Khalil ◽  
M. Shalaby
Keyword(s):  
Standard Model ◽  
Gauge Boson ◽  
Cross Sections ◽  
Branching Ratios ◽  
Higgs Production ◽  
Neutrino Masses ◽  
Natural Explanation ◽  
The Standard Model ◽  
The Cross

We present the phenomenology of the low scale U(1)B–L extension of the standard model and its implications at LHC. We show that this model provides a natural explanation for the presence of three right-handed neutrinos and can naturally account the observed neutrino masses and mixing. We study the decay and production of the extra gauge boson and the SM singlet scalar (heavy Higgs) predicted in this type of models. We find that the cross sections of the SM-like Higgs production are reduced by ~ 20% – 30%, while its decay branching ratios remain intact. The extra Higgs has relatively small cross sections and the branching ratios of Z′ → l+l− are of order ~ 20% compared to ~ 3% of the SM results.

scholarly journals STANDARD MODEL HIGGS COMBINED RESULT FROM CDF

2001 ◽  
Vol 16 (supp01b) ◽  
pp. 825-827
Author(s):  
◽  
JOÃO GUIMARÃES DA COSTA
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Z Boson ◽  
Decay Channel ◽  
Vector Boson ◽  
Associated Production ◽  
The Standard Model ◽  
The Individual ◽  
Cross Section Limit

The Tevatron is expected to be most sensitive to the Standard Model Higgs in its associated production with a W or Z boson. The Collider Detector at Fermilab (CDF) has performed individual searches for such production in each decay channel of the vector boson, assuming that the Higgs decays to [Formula: see text]. These searches use data collected by CDF during the 1992-95 run. The individual results are reviewed, and a combined cross section limit is presented.

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 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 $K_L\to\gamma\nu\bar\nu$ DECAY BEYOND THE STANDARD MODEL

2003 ◽  
Vol 18 (14) ◽  
pp. 977-982 ◽  
Author(s):  
JI-HAO JIANG ◽  
DAO-NENG GAO ◽  
MU-LIN YAN
Keyword(s):  
Standard Model ◽  
Branching Ratios ◽  
Beyond The Standard Model ◽  
Upper Limit ◽  
The Standard Model

The decay [Formula: see text] is investigated beyond the standard model. Interestingly, the upper limit of the CP-conserving and CP-violating branching ratios of the decay, induced from the possible extensions of the standard model, would be larger than the corresponding branching ratios given in the standard model respectively, and it is expected that the CP-violating part could be enhanced.

scholarly journals ELECTROWEAK UNIFICATION OF QUARKS AND LEPTONS IN A GAUGE GROUP SUC(3) × SU(4) × UX(1)

2012 ◽  
Vol 27 (21) ◽  
pp. 1250117 ◽  
Author(s):  
FAYYAZUDDIN
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Gauge Group ◽  
Lower Limit ◽  
Z Boson ◽  
Early Stage ◽  
Mass Scale ◽  
The Standard Model ◽  
Vector Bosons ◽  
The Universe

A model for electroweak unification of quarks and leptons, in a gauge group SUC(3) × SU(4) × UX(1) is constructed. The model requires, three generations of quarks and leptons which are replicas (mirror) of the standard quarks and leptons. The gauge group SU(4) × UX(1) is broken in such a way so as to reproduce standard model and to generate heavy masses for the vector bosons [Formula: see text], the leptoquarks and mirror fermions. It is shown lower limit on mass scale of mirror fermions is [Formula: see text], E- being the lightest mirror fermion coupled to Z boson. As the universe expands, the heavy matter is decoupled at an early stage of expansion and may be a source of dark matter. Leptoquarks in the model connect the standard model and mirror fermions. Baryon genesis in our universe implies antibaryon genesis in mirror universe.

scholarly journals STUDY OF RADIATIVE LEPTONIC D MESON DECAYS

2000 ◽  
Vol 15 (34) ◽  
pp. 2087-2103 ◽  
Author(s):  
C. Q. GENG ◽  
C. C. LIH ◽  
WEI-MIN ZHANG
Keyword(s):  
Standard Model ◽  
Quark Model ◽  
D Meson ◽  
Branching Ratios ◽  
Light Front ◽  
Meson Decays ◽  
The Standard Model

We study the radiative leptonic D meson decays of [Formula: see text], [Formula: see text] and D0→ l+l-γ (l=e, μ) within the light front quark model. In the standard model, we find that the decay branching ratios of [Formula: see text], [Formula: see text] and [Formula: see text] are 6.9×10-6 (7.7×10-5), 2.5×10-5 (2.6×10-4), and 6.0×10-6 (3.2×10-4), and that of D0→l+l-γ (l=e, μ) and [Formula: see text] are 6.3×10-11 and 2.7×10-16, respectively.

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