scholarly journals CharmlessBc→PP,PVDecays in the QCD Factorization Approach

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Na Wang
Keyword(s):  
Standard Model ◽  
Gluon Propagator ◽  
Branching Ratios ◽  
Wave Functions ◽  
Factorization Approach ◽  
Lhcb Experiment ◽  
Qcd Factorization ◽  
Running Coupling ◽  
The Standard Model ◽  
Weak Annihilation

The charmlessBc→PP,PVdecays (wherePandVdenote the light pseudoscalar and vector mesons, resp.) can occur only via the weak annihilation diagrams within the Standard Model. In this paper, we study these kinds of decays in the framework of QCD factorization, by adopting two different schemes: scheme I is similar to the method usually adopted in the QCD factorization approach, while scheme II is based on the infrared behavior of gluon propagator and running coupling. For comparison, in our calculation, we adopt three kinds of wave functions forBcmeson. The branching ratios based on the two schemes are given. It is found that (a) the predicted branching ratios in scheme I are, however, quite small and almost impossible to be measured at the LHCb experiment and (b) in scheme II, by assigning a dynamical gluon mass to the gluon propagator, we can avoid enhancements of the contribution from soft endpoint region. The strength of annihilation contributions predicted in scheme II is enhanced compared to that obtained in scheme I.

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 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 $K_L\to\gamma\nu\bar\nu$ 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 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.

scholarly journals Branching Fractions andCPAsymmetries ofB→K0*1430ρωandB→K0*1430ϕDecays in the Family NonuniversalZ′Model

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Ying Li ◽  
En-Lei Wang ◽  
Hong-Yan Zhang
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Branching Fractions ◽  
Qcd Factorization ◽  
The Family ◽  
The Standard Model

Within the QCD factorization framework, we investigate the branching fractions and the directCPasymmetries of decaysB→K0*1430ρωandB→K0*1430ϕunder two different scenarios in the standard model and the family nonuniversalZ′model. We find that the annihilation terms play crucial roles in these decays and lead to the major uncertainties. For decaysB-→K0*-1430ρ0ω, the newZ′boson could change the branching fractions remarkably. However, for other decays, its contribution might be clouded by large uncertainties from annihilations. Unfortunately, neither the standard model nor theZ′model can reproduce all experimental data simultaneously under one certain scenario. We also noted that the directCPasymmetries ofB-→K0*-1430ρ0ωcould be used to identify theK0*1430meson and search for the contribution of newZ′boson.

scholarly journals Study of the Υ(1S) → DP decays

2021 ◽  
pp. 2150061
Author(s):  
Yueling Yang ◽  
Mingfei Duan ◽  
Junliang Lu ◽  
Jinshu Huang ◽  
Junfeng Sun
Keyword(s):  
Standard Model ◽  
Perturbative Qcd ◽  
Branching Ratios ◽  
New Physics ◽  
High Luminosity ◽  
Weak Decays ◽  
The Standard Model

Inspired by the potential prospects of high-luminosity dedicated colliders and the high enthusiasms in searching for new physics in the flavor sector at the intensity frontier, the [Formula: see text], [Formula: see text] and [Formula: see text] weak decays are studied with the perturbative QCD approach. It is found within the standard model that the branching ratios for the concerned processes are tiny, about [Formula: see text], and far beyond the detective ability of current experiments unless there exists some significant enhancements from a novel interaction.

scholarly journals Unleashing the full power of LHCb to probe Stealth New Physics

2021 ◽  
Author(s):  
Martino Borsato ◽  
Xabier Cid-Vidal ◽  
Yuhsin Tsai ◽  
Carlos Vázquez Sierra ◽  
Jose Francisco Zurita ◽  
...  
Keyword(s):  
Large Hadron Collider ◽  
Standard Model ◽  
Hadron Collider ◽  
Theoretical Models ◽  
New Physics ◽  
Precision Measurements ◽  
Beyond The Standard Model ◽  
Lhcb Experiment ◽  
The Standard Model ◽  
Full Power

Abstract In this paper, we describe the potential of the LHCb experiment to detect Stealth physics. This refers to dynamics beyond the Standard Model that would elude searches that focus on energetic objects or precision measurements of known processes. Stealth signatures include long-lived particles and light resonances that are produced very rarely or together with overwhelming backgrounds. We will discuss why LHCb is equipped to discover this kind of physics at the Large Hadron Collider and provide examples of well-motivated theoretical models that can be probed with great detail at the experiment.

MEASUREMENT OF THE W PAIR PRODUCTION CROSS SECTION AND W BRANCHING RATIOS WITH THE DELPHI DETECTOR

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 348-350
Author(s):  
FABIO COSSUTTI
Keyword(s):  
Standard Model ◽  
Pair Production ◽  
Cross Section ◽  
Production Cross Section ◽  
Production Cross ◽  
Branching Ratios ◽  
Centre Of Mass ◽  
Delphi Detector ◽  
The Standard Model ◽  
Pair Production Cross Section

Data collected with the DELPHI detector at centre-of-mass energies up to the highest values explored by the LEP collider of about 206 GeV have been used to extract preliminary values of the cross-section for the process e+e- → W+W-. The branching ratios of the W decay were also measured; from them the value of |Vcs| was extracted. The results are compared with the most recent calculations in the framework of the Standard Model.

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