scholarly journals Study of Rare Mesonic Decays Involving Di-Neutrinos in Their Final State

2018 ◽  
Vol 2018 ◽  
pp. 1-20
Author(s):  
Azeem Mir ◽  
Farida Tahir ◽  
Shakeel Mahmood ◽  
Shi- Hai Dong
Keyword(s):  
Branching Fractions ◽  
New Physics ◽  
Supersymmetric Model ◽  
Final State ◽  
Yukawa Couplings ◽  
Leptonic Decays ◽  
Pseudoscalar Mesons ◽  
Theoretical Predictions ◽  
Minimal Supersymmetric Model

We have studied phenomenological implication of R-parity violating (Rp) Minimal Supersymmetric Model (MSSM) via analyses of pure leptonic (M→νν¯) and semileptonic decays of pseudoscalar mesons (M→Xνν¯). These analyses involve comparison between theoretical predictions made by Rp MSSM and the Standard Model (SM) with the experimental results like branching fractions (Br) of the said process. We have found, in general, that Rp contribution dominates over the SM contribution, i.e., by a factor of 10 for the pure leptonic decays of KL,S and by 102 and 104 in case of Bs and Bd, respectively. Furthermore, the limits obtained on Rp Yukawa couplings (λαkβ′λαkγ′⁎) by using Br  (M→Xνν¯) are used to calculate Br  (M→νν¯). This demonstrates the role of Rp MSSM as a viable model for the study of new physics contribution in rare decays at places like Super B factories, KOTO (J-PARC) and NA62 at CERN.

scholarly journals PROBING NEW PHYSICS FROM TOP QUARK FCNC PROCESS AT LHC: A MINI REVIEW

2008 ◽  
Vol 23 (21) ◽  
pp. 3343-3347 ◽  
Author(s):  
JIN MIN YANG
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
New Physics ◽  
Supersymmetric Model ◽  
The Standard Model ◽  
Minimal Supersymmetric Model

Since the top quark FCNC processes are extremely supressed in the Standard Model (SM) but could be greatly enhanced in some new physics models, they could serve as a smoking gun for new physics hunting at the LHC. In this brief review we summarize the new physics predictions for various top quark FCNC processes at the LHC by focusing on two typical models: the minimal supersymmetric model (MSSM) and the topcolor-assisted technicolor (TC2) model. The conclusion is: (1) Both new physics models can greatly enhance the SM predictions by several orders; (2) The TC2 model allows for largest enhancement, and for each channel the maximal prediction is much larger than in the MSSM; (3) Compared with the 3σ sensitivity at the LHC, only a couple of channels are accessible for the MSSM while most channles are accesible for the TC2 model.

scholarly journals UNITARY CHIRAL DYNAMICS IN J/Ψ DECAYS INTO VPP AND THE ROLE OF THE SCALAR MESONS

2005 ◽  
Vol 20 (08n09) ◽  
pp. 1897-1900 ◽  
Author(s):  
L. ROCA ◽  
J. E. PALOMAR ◽  
E. OSET ◽  
H. C. CHIANG
Keyword(s):  
Final State Interaction ◽  
Axial Vector ◽  
Final State ◽  
Mass Distributions ◽  
Scalar Mesons ◽  
Pseudoscalar Mesons ◽  
Unitary Approach ◽  
Chiral Unitary Approach ◽  
Ozi Rule

We make a theoretical study of the J/Ψ decays into ωππ, ϕππ, [Formula: see text] and [Formula: see text] using the techniques of the chiral unitary approach stressing the important role of the scalar resonances dynamically generated through the final state interaction of the two pseudoscalar mesons. We also discuss the importance of new mechanisms with intermediate exchange of vector and axial-vector mesons and the role played by the OZI rule in the J/Ψϕππ vertex, quantifying its effects. The results nicely reproduce the experimental data for the invariant mass distributions in all the channels considered.

scholarly journals SIGNATURES OF NEW PHYSICS IN DILEPTONIC B-DECAYS

2006 ◽  
Vol 21 (12) ◽  
pp. 2617-2634 ◽  
Author(s):  
S. RAI CHOUDHURY ◽  
A. S. CORNELL ◽  
NAVEEN GAUR ◽  
G. C. JOSHI
Keyword(s):  
B Mesons ◽  
B Meson ◽  
Higgs Doublet ◽  
New Physics ◽  
Final State ◽  
Decay Modes ◽  
Leptonic Decays ◽  
The Standard Model ◽  
Doublet Model ◽  
Two Higgs Doublet Model

Leptonic decays of B-mesons are theoretically very clean probes for testing the Standard Model (SM) and possible physics beyond it. Amongst the various leptonic decays of the B-meson, the pure dileptonic decay B → ℓ+ ℓ- is very important, as this mode is helicity suppressed in the SM but can be substantially enhanced in some of the models beyond the SM, such as supersymmetric (SUSY) theories and the two Higgs doublet model (2HDM). Although the purely dileptonic decay mode is helicity suppressed in the SM its associated mode B → ℓ+ ℓ-γ does not have the same suppression, due to the presence of γ in the final state. In this paper we will also analyze the effects of enhanced Z-penguins on these two decay modes.

scholarly journals Polarization in (quasi-)two-body decays and new physics

2019 ◽  
Vol 79 (12) ◽  
Author(s):  
Z. J. Ajaltouni ◽  
E. Di Salvo
Keyword(s):  
Time Reversal ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Covariant Formalism ◽  
Final State ◽  
Leptonic Decays ◽  
Weak Decays ◽  
The Standard Model ◽  
Final State Interactions ◽  
Major Attention

AbstractWe consider two-body and quasi-two-body decays of the type $$f_1 \rightarrow f_2 B$$f1→f2B, where $$f_1$$f1 and $$f_2$$f2 are spin-1/2 fermions and B a spin-0 or spin-1 boson. After recalling the non-covariant formalism for decay amplitudes, we derive the expression of the differential decay width and of the polarizations of the final spinning particles, both on- and off-shell. We find an intriguing geometrical interpretation of the results about the polarization. We also illustrate some methods for measuring the polarizations of the resonances and for optimizing data analysis. Then we propose applications to semi-leptonic weak decays, with a major attention to the T-odd component of the polarization; this may help to find, simultaneously, possible time-reversal violations and hints to physics beyond the standard model. We suggest also a CPT test. Last, we discuss some T-odd observables for the production process of $$f_1$$f1 and for the study of the strong final state interactions of non-leptonic decays.

scholarly journals Unified minimal supersymmetric model with large Yukawa couplings

1996 ◽  
Vol 53 (3) ◽  
pp. 1553-1585 ◽  
Author(s):  
Riccardo Rattazzi ◽  
Uri Sarid
Keyword(s):  
Supersymmetric Model ◽  
Yukawa Couplings ◽  
Minimal Supersymmetric Model

scholarly journals QED factorization of non-leptonic B decays

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Martin Beneke ◽  
Philipp Böer ◽  
Jan-Niklas Toelstede ◽  
K. Keri Vos
Keyword(s):  
Weak Interactions ◽  
Branching Fractions ◽  
Form Factors ◽  
New Physics ◽  
Final States ◽  
Final State ◽  
Qcd Factorization ◽  
Factorization Formula ◽  
Qed Effects ◽  
Electrically Charged

Abstract We show that the QCD factorization approach for B-meson decays to charmless hadronic two-body final states can be extended to include electromagnetic corrections. The presence of electrically charged final-state particles complicates the framework. Nevertheless, the factorization formula takes the same form as in QCD alone, with appropriate generalizations of the definitions of light-cone distribution amplitudes and form factors to include QED effects. More precisely, we factorize QED effects above the strong interaction scale ΛQCD for the non-radiative matrix elements $$ \left\langle {M}_1{M}_2\left|{Q}_i\right|\overline{B}\right\rangle $$ M 1 M 2 Q i B ¯ of the current-current operators from the effective weak interactions. The rates of the branching fractions for the infrared-finite observables $$ \overline{B}\to {M}_1{M}_2\left(\gamma \right) $$ B ¯ → M 1 M 2 γ with photons of maximal energy ∆E ≪ ΛQCD is then obtained by multiplying with the soft-photon exponentiation factors. We provide first estimates for the various electromagnetic corrections, and in particular quantify their impact on the πK ratios and sum rules that are often used as diagnostics of New Physics.

scholarly journals The role of right-handed neutrinos in b → cτ (πντ, ρντ, μ$$ \overline{\nu} $$μντ)$$ \overline{\nu} $$τ from visible final-state kinematics

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Neus Penalva ◽  
Eliecer Hernández ◽  
Juan Nieves
Keyword(s):  
Semileptonic Decay ◽  
Massive Particle ◽  
New Physics ◽  
Experimental Information ◽  
Final State ◽  
Spin Asymmetries ◽  
Decay Modes ◽  
Lepton Flavor ◽  
Rule Out

Abstract In the context of lepton flavor universality violation (LFUV) studies, we fully derive a general tensor formalism to investigate the role that left- and right-handed neutrino new-physics (NP) terms may have in b → cτ$$ \overline{\nu} $$ ν ¯ τ transitions. We present, for several extensions of the Standard Model (SM), numerical results for the Λb → Λcτ$$ \overline{\nu} $$ ν ¯ τ semileptonic decay, which is expected to be measured with precision at the LHCb. This reaction can be a new source of experimental information that can help to confirm, or maybe rule out, LFUV presently seen in $$ \overline{B} $$ B ¯ meson decays. The present study analyzes observables that can help in distinguishing between different NP scenarios that otherwise provide very similar results for the branching ratios, which are our currently best hints for LFUV. Since the τ lepton is very short-lived, we consider three subsequent τ-decay modes, two hadronic πντ and ρντ and one leptonic μ$$ \overline{\nu} $$ ν ¯ μντ, which have been previously studied for $$ \overline{B} $$ B ¯ → D(*) decays. Within the tensor formalism that we have developed in previous works, we re-obtain the expressions for the differential decay width written in terms of visible (experimentally accessible) variables of the massive particle created in the τ decay. There are seven different τ angular and spin asymmetries that are defined in this way and that can be extracted from experiment. Those asymmetries provide observables that can help in constraining possible SM extensions.

An Experimental Investigation of Auditors' Liability: Implications for Social Welfare and Exploration of Deviations from Theoretical Predictions

2000 ◽  
Vol 75 (4) ◽  
pp. 429-451 ◽  
Author(s):  
Ronald R. King ◽  
Rachel Schwartz
Keyword(s):  
Experimental Investigation ◽  
Social Welfare ◽  
Strict Liability ◽  
Liability Rule ◽  
Optimal Response ◽  
Legal Regimes ◽  
Theoretical Predictions ◽  
Best Responses

This paper reports the results of an experiment designed to investigate how legal regimes affect social welfare. We investigate four legal regimes, each consisting of a liability rule (strict or negligence) and a damage measure (out-of-pocket or independent-of-investment). The results of the experiment are for the most part consistent with the qualitative predictions of Schwartz's (1997) model; however, subjects' actual choices deviate from the point predictions of the model. We explore whether these deviations arise because: (1) subjects form faulty anticipations of their counterparts' actions and/or (2) subjects do not choose the optimal responses given their anticipations. We find that subjects behave differently under the four regimes in terms of anticipation errors and departures from best responses. For example, subjects playing the role of auditors anticipate investments most accurately under the regime with strict liability combined with out-of-pocket damages, but are least likely to choose the optimal response given their anticipations. This finding implies that noneconomic factors likely play a role in determining subjects' choices.

scholarly journals A Stochastic Kinetic Type Reactions Model for COVID-19

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1221
Author(s):  
Giorgio Sonnino ◽  
Fernando Mora ◽  
Pasquale Nardone
Keyword(s):  
Real Data ◽  
Stochastic Noise ◽  
Mathematical Basis ◽  
Sis Model ◽  
Theoretical Predictions ◽  
Coronavirus Infection ◽  
Massive Distribution ◽  
Second Wave ◽  
Stochastic Sis Model

We propose two stochastic models for the Coronavirus pandemic. The statistical properties of the models, in particular the correlation functions and the probability density functions, were duly computed. Our models take into account the adoption of lockdown measures as well as the crucial role of hospitals and health care institutes. To accomplish this work we adopt a kinetic-type reaction approach where the modelling of the lockdown measures is obtained by introducing a new mathematical basis and the intensity of the stochastic noise is derived by statistical mechanics. We analysed two scenarios: the stochastic SIS-model (Susceptible ⇒ Infectious ⇒ Susceptible) and the stochastic SIS-model integrated with the action of the hospitals; both models take into account the lockdown measures. We show that, for the case of the stochastic SIS-model, once the lockdown measures are removed, the Coronavirus infection will start growing again. However, the combined contributions of lockdown measures with the action of hospitals and health institutes is able to contain and even to dampen the spread of the SARS-CoV-2 epidemic. This result may be used during a period of time when the massive distribution of vaccines in a given population is not yet feasible. We analysed data for USA and France. In the case of USA, we analysed the following situations: USA is subjected to the first wave of infection by Coronavirus and USA is in the second wave of SARS-CoV-2 infection. The agreement between theoretical predictions and real data confirms the validity of our approach.

scholarly journals Dual subtractions

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Renato Maria Prisco ◽  
Francesco Tramontano
Keyword(s):  
Field Theory ◽  
Quantum Field ◽  
Matrix Elements ◽  
Leading Order ◽  
Initial State ◽  
Final State ◽  
Dual Representation ◽  
Subtraction Scheme ◽  
Theoretical Predictions ◽  
Perturbative Quantum

Abstract We propose a novel local subtraction scheme for the computation of Next-to-Leading Order contributions to theoretical predictions for scattering processes in perturbative Quantum Field Theory. With respect to well known schemes proposed since many years that build upon the analysis of the real radiation matrix elements, our construction starts from the loop diagrams and exploits their dual representation. Our scheme implements exact phase space factorization, handles final state as well as initial state singularities and is suitable for both massless and massive particles.

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