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.

SEARCH FOR NEW PHYSICS IN eμX DATA AT THE TEVATRON USING SLEUTH: A QUASI-MODEL-INDEPENDENT SEARCH STRATEGY FOR NEW PHYSICS

2001 ◽  
Vol 16 (supp01b) ◽  
pp. 888-890
Author(s):  
◽  
BRUCE KNUTESON
Keyword(s):  
Standard Model ◽  
Search Strategy ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Final States ◽  
Final State ◽  
The Standard Model ◽  
Model Independent

We present a quasi-model-independent search for physics beyond the standard model. We define final states to be studied, and construct a rule that identifies a set of variables appropriate for any particular final state. A new algorithm ("Sleuth") searches for regions of excess in the space of those variables and quantifies the significance of any detected excess. After demonstrating the sensititvity of the method, we apply it to the semi-inclusive channel eμX collected in ≈108 pb -1 of [Formula: see text] collisions at [Formula: see text] at the DØ experiment at the Fermilab Tevatron. We find no evidence of new high pT physics in this sample.

scholarly journals A model-independent analysis of $$b{\rightarrow }s\mu ^{+}\mu ^{-}$$transitions with GAMBIT ’s FlavBit

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Jihyun Bhom ◽  
Marcin Chrzaszcz ◽  
Farvah Mahmoudi ◽  
Markus T. Prim ◽  
Pat Scott ◽  
...  
Keyword(s):  
Standard Model ◽  
Neutral Current ◽  
Current Data ◽  
Operator Product ◽  
Beyond The Standard Model ◽  
Vector Coupling ◽  
Independent Analysis ◽  
The Standard Model ◽  
Model Independent ◽  
Best Fit

AbstractThe search for flavour-changing neutral current effects in B-meson decays is a powerful probe of physics beyond the Standard Model. Deviations from SM behaviour are often quantified by extracting the preferred values of the Wilson coefficients of an operator product expansion. We use the module of the package to perform a simultaneous global fit of the Wilson coefficients $$C_7$$ C 7 , $$C_9$$ C 9 , and $$C_{10}$$ C 10 using a combination of all current data on $$b{\rightarrow }s\mu ^{+}\mu ^{-}$$ b → s μ + μ -  transitions. We further extend previous analyses by accounting for the correlated theoretical uncertainties at each point in the Wilson coefficient parameter space, rather than deriving the uncertainties from a Standard Model calculation. We find that the best fit deviates from the SM value with a significance of 6.6$$\sigma $$ σ . The largest deviation is associated with a vector coupling of muons to b and s quarks.

scholarly journals Single production of vector-like bottom quark at the LHeC

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Xue Gong ◽  
Chong-Xing Yue ◽  
Hai-Mei Yu ◽  
Dong Li
Keyword(s):  
Standard Model ◽  
Bottom Quark ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Fast Simulation ◽  
Decay Properties ◽  
The Standard Model ◽  
Single Production ◽  
Model Independent ◽  
Better Than

AbstractExistences of vector-like quarks (VLQs) are predicted in many new physics scenarios beyond the Standard Model (SM). We study the possibility of detecting the vector-like bottom quark (VLQ-B) being the SU(2) singlet with electric charge $$-1/3$$ - 1 / 3 at Large Hadron electron Collider (LHeC) in a model-independent framework. The decay properties and single production of VLQ-B at the LHeC are explored. Three types of signatures are investigated. By carrying out a fast simulation for the signals and the corresponding backgrounds, the signal significances are obtained. Our numerical results show that detecting of VLQ-B via the semileptonic channel is better than via the fully hadronic or leptonic channel.

scholarly journals EFFECT OF BOTH Z AND Z′ MEDIATED FLAVOR-CHANGING NEUTRAL CURRENTS ON THE BARYONIC RARE DECAY Λb→Λℓ+ℓ-

2009 ◽  
Vol 24 (32) ◽  
pp. 6223-6235 ◽  
Author(s):  
S. SAHOO ◽  
C. K. DAS ◽  
L. MAHARANA
Keyword(s):  
Standard Model ◽  
Z Boson ◽  
Rare Decay ◽  
Branching Ratio ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Neutral Currents ◽  
Flavor Changing ◽  
The Standard Model ◽  
Flavor Changing Neutral Currents

We study the effect of both Z and Z′ mediated flavor-changing neutral currents (FCNCs) on the Λb→Λℓ+ℓ-(ℓ = μ, τ) rare decay. We find the branching ratio is reasonably enhanced from its Standard Model value due to the effect of both Z and Z′ mediated FCNCs, and gives the possibility of new physics beyond the Standard Model. The contribution of Z′ boson depends upon the precise value of MZ′.

scholarly journals Probing QCD dynamics and the standard model with $$ {D}_{(s)}^{+}\to {P}_1^{+}{P}_2^0\gamma $$ decays

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Nico Adolph ◽  
Gudrun Hiller
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
New Physics ◽  
Resonance Structure ◽  
Cp Asymmetry ◽  
The Standard Model ◽  
Weak Annihilation ◽  
Channel Dependent ◽  
Cabibbo Suppressed ◽  
Three Body

Abstract We compute 10 radiative three-body decays of charged charmed mesons $$ {D}^{+}\to {P}_1^{+}{P}_2^0\gamma $$ D + → P 1 + P 2 0 γ and $$ {D}_s\to {P}_1^{+}{P}_2^0\gamma $$ D s → P 1 + P 2 0 γ , P1,2 = π, K, in leading order QCDF, HHχPT and the soft photon approximation. We work out decay distributions and asymmetries in the standard model and with new physics in the electromagnetic dipole operators. The forward-backward asymmetry is suitable to probe the QCD frameworks, in particular the s-channel dependent weak annihilation contributions in QCDF against the markedly different resonance structure in HHχPT. These studies can be performed with Cabibbo-favored modes Ds → π+π0γ, $$ {D}^{+}\to {\pi}^{+}{\overline{K}}^0\gamma $$ D + → π + K ¯ 0 γ and $$ {D}_s\to {K}^{+}{\overline{K}}^0\gamma $$ D s → K + K ¯ 0 γ with $$ \mathcal{O}\left({10}^{-4}-{10}^{-3}\right)\hbox{-} \mathrm{level} $$ O 10 − 4 − 10 − 3 ‐ level branching ratio, which are standard model-like and induced by different hadronic dynamics. Understanding of the latter can therefore be improved in a data-driven way and sharpens the interpretation of standard model tests. Singly Cabibbo-suppressed modes such as D+ → π+π0γ, Ds → π+K0γ, Ds → K+π0γ with branching ratios within ∼ 10−5–10−4 are sensitive to new physics that can be signalled in the forward-backward asymmetry and in the CP-asymmetry of the rate, ideally in the Dalitz region but also in single differential distributions. Results complement those with neutral D0→ P1P2γ decays.

scholarly journals Model-Independent Searches for New Physics in Multi-Body Invariant Masses

Universe ◽  
2021 ◽  
Vol 7 (9) ◽  
pp. 333
Author(s):  
Sergei Chekanov ◽  
Smita Darmora ◽  
Wasikul Islam ◽  
Carlos E. M. Wagner ◽  
Jinlong Zhang
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Similar Model ◽  
The Past ◽  
The Standard Model ◽  
Model Independent ◽  
Multi Body

Model-independent searches for physics beyond the Standard Model typically focus on invariant masses of two objects (jets, leptons or photons). In this study, we explore opportunities for similar model-agnostic searches in multi-body invariant masses. In particular, we focus on the situations in which new physics can be observed in a model-independent way in three and four-body invariant masses of jets and leptons. Such searches may have good prospects in finding new physics in the situations when two-body invariant masses, which have been extensively explored at collider experiments in the past, cannot provide sufficient signatures for experimental observations.

scholarly journals New physics at the FCC-ee: indirect discovery potential

2021 ◽  
Vol 136 (9) ◽  
Author(s):  
Jorge de Blas
Keyword(s):  
Effective Field Theories ◽  
Standard Model ◽  
New Physics ◽  
Effective Field ◽  
Point Of View ◽  
Field Theories ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Discovery Potential ◽  
Model Independent

AbstractWe review the projected sensitivity to physics beyond the Standard Model via indirect searches at the Future$$e+e-$$ e + e - Circular Collider (FCC-ee). The indirect sensitivity to new physics is discussed both from a model-independent perspective, using the formalism of Effective Field Theories, but also from the point of view of more specific classes of well-motivated models.

Lepton flavor violating decays in model

2019 ◽  
Vol 97 (12) ◽  
pp. 1270-1276
Author(s):  
P. Nayek ◽  
P. Maji ◽  
S. Sahoo
Keyword(s):  
Standard Model ◽  
Neutral Current ◽  
Branching Ratios ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Lepton Flavor ◽  
Flavor Changing ◽  
The Standard Model ◽  
Flavor Changing Neutral Current ◽  
Text Model

Motivated by the hints of lepton flavor violating (LFV) decays, we study Bd,s → μτ, Bs,d → τe, and τ– → e– + e+ + e– decays in [Formula: see text] model. These LFV decays present interesting patterns that may reveal the shape of new physics beyond the standard model. Considering the effect of both Z- and [Formula: see text]-mediated flavor-changing neutral current we calculate the branching ratios for these decays. We find the branching ratios [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text].

scholarly journals Study of the rare decays Bs,d∗→ l+l− in Z′ model

2017 ◽  
Vol 32 (14) ◽  
pp. 1750075 ◽  
Author(s):  
Debika Banerjee ◽  
Priya Maji ◽  
Sukadev Sahoo
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Rare Decays ◽  
Branching Ratio ◽  
Branching Ratios ◽  
New Physics ◽  
Leptonic Decays ◽  
The Standard Model ◽  
Text Model ◽  
Vector Formula

The rare decays [Formula: see text] are important to probe the flavor sector of the standard model and to search new physics beyond the SM. Unlike pseudoscalar [Formula: see text] meson, the leptonic decays of vector [Formula: see text] mesons are not chirally suppressed which compensates for their short lifetimes, and results in significant branching ratios. In this paper, we estimate the branching ratios of [Formula: see text][Formula: see text] rare decays in [Formula: see text] model which is an extension of the SM with an extra [Formula: see text] gauge symmetry. We find that the branching ratios are increased from their corresponding standard model values and vary with the mass of [Formula: see text] boson. The lower the mass of [Formula: see text] boson, the higher is the branching ratio.

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