scholarly journals SUPERSYMMETRIC CONTRIBUTIONS TO B→K π IN THE VIEW OF RECENT EXPERIMENTAL RESULTS

2008 ◽  
Vol 23 (05) ◽  
pp. 777-785
Author(s):  
SHAABAN KHALIL
Keyword(s):  
Standard Model ◽  
Branching Ratios ◽  
Experimental Measurements ◽  
Apparent Discrepancy ◽  
Cp Asymmetry ◽  
Essential Requirement ◽  
Electroweak Penguin ◽  
The Standard Model ◽  
Natural Solution ◽  
Cp Asymmetries

Supersymmetric contributions to the branching ratios and CP asymmetries of B→K π decays are analyzed in view of recent experimental measurements. We show that supersymmetry can still provide a natural solution to the apparent discrepancy between the CP asymmetry results and the Standard Model expectations. We emphasize that chargino contributions may enhance the electroweak penguin effects that can resolve to the puzzle of the CP asymmetries of B→Kπ. We also point out that a nonuniversal A-terms is an essential requirement for this solution.

scholarly journals Enhanced CP asymmetries in $$B \rightarrow K \mu ^+ \mu ^-$$

2020 ◽  
Vol 80 (10) ◽  
Author(s):  
Damir Bečirević ◽  
Svjetlana Fajfer ◽  
Nejc Košnik ◽  
Aleks Smolkovič
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Cp Asymmetry ◽  
Close Vicinity ◽  
The Standard Model ◽  
Before And After ◽  
Cp Asymmetries

AbstractWe show that the current values of $$R_K^\mathrm {exp}$$ R K exp and $$R_{K^*}^\mathrm {exp}$$ R K ∗ exp can be accommodated by allowing a nonzero New Physics coupling $$\delta C_9^{\mu \mu }$$ δ C 9 μ μ to be complex, both in the scenario in which only $$\delta C_9^{\mu \mu }$$ δ C 9 μ μ is affected, and in the scenario with complex $$\delta C_{9,10}^{\mu \mu }$$ δ C 9 , 10 μ μ satisfying $$\delta C_{9}^{\mu \mu }=-\delta C_{10}^{\mu \mu }$$ δ C 9 μ μ = - δ C 10 μ μ . A presence of the weak CP-violating phase can then be tested by measuring the CP-asymmetry, $$\mathcal {A}_\mathrm {CP}$$ A CP . We show that this asymmetry is enhanced around the peak of each $$c\bar{c}$$ c c ¯ -resonance, and in fact more pronounced in the close vicinity of $$J/\psi $$ J / ψ and $$\psi (2S)$$ ψ ( 2 S ) . Therefore, measuring $$\mathcal {A}_\mathrm {CP}$$ A CP before and after the resonances’ peak could be revelatory of the CP-violation that originates from beyond the Standard Model, or to be a significant constrain when building a realistic scenario of New Physics.

scholarly journals Direct CP violation in $$D^+ \rightarrow K^0({\bar{K}}^0) \pi ^+$$ decays as a probe for new physics

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
David Delepine ◽  
Gaber Faisel ◽  
Carlos A. Ramirez
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Parameter Space ◽  
Higgs Doublet ◽  
New Physics ◽  
Cp Asymmetry ◽  
The Standard Model ◽  
Doublet Model ◽  
Two Higgs Doublet Model ◽  
Cp Asymmetries

Abstract In this paper we investigate CP violation in charged decays of D meson. Particularly, we study the direct CP asymmetry of the Cabibbo favored non-leptonic $$D^+ \rightarrow {\bar{K}}^0 \pi ^+$$D+→K¯0π+ and the doubly Cabibbo-suppressed decay mode $$D^+ \rightarrow K^0 \pi ^+$$D+→K0π+ within standard model, two Higgs doublet model with generic Yukawa structure and left right symmetric models. In the standard model, we first derive the contributions from box and di-penguin diagrams contributing to their amplitudes which are relevant to the generation of the weak phases essential for non-vanishing direct CP violation. Then, we show that the generated phases are so tiny leading to null direct CP asymmetries of both decay modes. Regarding the two Higgs doublet model with generic Yukawa structure, after taking into account all constraints on the parameter space of the model, we show that the weak phases of the amplitudes can be enhanced compared to the standard model ones. However, the enhancement is still not enough to have sizable direct CP asymmetries. Finally, within left right symmetric models, we find that $$|A^{SM+LR}_{CP} (D^+ \rightarrow {\bar{K}}^0 \pi ^+)|\lesssim \mathcal {O}(10^{-3})$$|ACPSM+LR(D+→K¯0π+)|≲O(10-3) after respecting all relevant constraints on the parameter space of the model.

scholarly journals U-SPIN TESTS OF THE STANDARD MODEL AND NEW PHYSICS

2008 ◽  
Vol 23 (16) ◽  
pp. 1175-1185 ◽  
Author(s):  
MAKIKO NAGASHIMA ◽  
ALEJANDRO SZYNKMAN ◽  
DAVID LONDON
Keyword(s):  
Standard Model ◽  
Branching Ratios ◽  
New Physics ◽  
The Standard Model ◽  
Cp Asymmetries

Within the standard model, a relation involving branching ratios and direct CP asymmetries holds for the B-decay pairs that are related by U-spin. The violation of this relation indicates new physics (NP). In this paper, we assume that the NP affects only the ΔS = 1 decays, and show that the NP operators are generally the same as those appearing in B → πK decays. The fit to the latest B → πK data shows that only one NP operator is sizeable. As a consequence, the relation is expected to be violated for only one decay pair: [Formula: see text] and [Formula: see text].

scholarly journals Probing for new physics with rare charm baryon (Λc, Ξc, Ωc) decays

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Marcel Golz ◽  
Gudrun Hiller ◽  
Tom Magorsch
Keyword(s):  
Standard Model ◽  
Branching Ratios ◽  
New Physics ◽  
Cp Asymmetry ◽  
Vector Coupling ◽  
Lepton Flavor ◽  
The Standard Model ◽  
Charm Baryon ◽  
Order Of Magnitude ◽  
Rare Charm

Abstract We analyze rare charm baryon decays within the standard model and beyond. We identify all null test observables in unpolarized Λc→ pℓ+ℓ−, ℓ = e, μ decays, and study the new physics sensitivities. We find that the longitudinal dilepton polarization fraction FL is sensitive to electromagnetic dipole couplings $$ {C}_7^{\left(\prime \right)} $$ C 7 ′ , and to the right-handed 4-fermion vector coupling $$ {C}_9^{\left(\prime \right)} $$ C 9 ′ . The forward-backward asymmetry, AFB, due to the GIM-suppression a standard model null test already, probes the left-handed axialvector 4-fermion coupling C10; its CP–asymmetry, $$ {A}_{\mathrm{FB}}^{\mathrm{CP}} $$ A FB CP probes CP-violating phases in C10. Physics beyond the standard model can induce branching ratios of dineutrino modes Λc→ pν$$ \overline{\nu} $$ ν ¯ up to a few times 10−5, and one order of magnitude smaller if lepton flavor universality is assumed, while standard model rates are negligible. Charged lepton flavor violation allows for striking signals into e±μ∓ final states, up to 10−6 branching ratios model-independently, and up to order 10−8 in leptoquark models. Related three-body baryon decays Ξc→ Σℓℓ, Ξc→ Λℓℓ and Ωc→ Ξℓℓ offer similar opportunities to test the standard model with |∆c| = |∆u| = 1 transitions.

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 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.

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

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