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 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.

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.

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 Rb, Rc and New Physics: An Updated Model Independent Analysis

1997 ◽  
Vol 12 (04) ◽  
pp. 723-742 ◽  
Author(s):  
P. Bamert
Keyword(s):  
Standard Model ◽  
Neutral Current ◽  
New Physics ◽  
Low Energy ◽  
Coupling Constant ◽  
A Value ◽  
Independent Analysis ◽  
The Standard Model ◽  
Necessary And Sufficient ◽  
Do So

We analyze LEP and SLC data from the 1995 Summer Conferences as well as from low energy neutral current experiments for signals of new physics. The reasons for doing this are twofold: first to explain the deviations from the Standard Model observed in Rb and Rc and second to constrain nonstandard contributions to couplings of the Z0 boson to all fermions and to the oblique parameters. We do so by comparing the data with the Standard Model as well as with a number of test hypotheses concerning the nature of the new physics. These include nonstandard [Formula: see text]-, [Formula: see text]- and [Formula: see text]-couplings as well as the couplings of the Z0 to fermions of the entire first, second and third generations and universal corrections to all up- and down-type quark couplings (as can arise see for example in Z' mixing models). We find that nonstandard [Formula: see text] couplings are both necessary and sufficient to explain the data and in particular the Rb anomaly. It is not possible to explain Rb, Rc and a value of the strong coupling constant consistent with low energy determinations invoking only nonstandard [Formula: see text]- and [Formula: see text]-couplings. To do so one has to have also new physics contributions to the [Formula: see text] or universal corrections to all [Formula: see text] couplings.

scholarly journals Studies of Missing Energy Decays at Belle II

2018 ◽  
Vol 46 ◽  
pp. 1860072
Author(s):  
Yinghui Guan
Keyword(s):  
Standard Model ◽  
Rare Decays ◽  
Neutral Current ◽  
Beyond The Standard Model ◽  
Missing Energy ◽  
Final State ◽  
Full Reconstruction ◽  
The Standard Model ◽  
Belle Ii ◽  
The Spectator

The Belle II experiment at the SuperKEKB collider is a major upgrade of the KEK “B factory” facility in Tsukuba, Japan. The machine is designed for an instantaneous luminosity of [Formula: see text], and the experiment is expected to accumulate a data sample of about 50 ab[Formula: see text]. With this amount of data, decays sensitive to physics beyond the Standard Model can be studied with unprecedented precision. One promising set of modes are physics processes with missing energy such as [Formula: see text], [Formula: see text], and [Formula: see text] decays. The [Formula: see text] decay provides one of the cleanest experimental probes of the flavour-changing neutral current process [Formula: see text], which is sensitive to physics beyond the Standard Model. However, the missing energies of the neutrinos in the final state makes the measurement challenging and requires full reconstruction of the spectator [Formula: see text] meson in [Formula: see text] events. This report discusses the expected sensitivities of Belle II for these rare decays.

scholarly journals Physics Beyond The Standard Model: Experimental

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 92-103 ◽  
Author(s):  
R. L. Culbertson
Keyword(s):  
Standard Model ◽  
Extra Dimensions ◽  
Large Extra Dimensions ◽  
High Energy ◽  
Higgs Bosons ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Model Independent

The search for physics beyond the Standard Model includes Technicolor particles, Higgs Bosons, compositeness, many variations of Supersymmetry, large extra dimensions, model-independent searches for anomalies, and other topics. This article reports a subset of these ongoing searches at the high-energy colliders, Tevatron, HERA and LEP.

scholarly journals THE EFFECT OF ELECTROMAGNETIC PROPERTIES OF NEUTRINOS ON THE PHOTON–NEUTRINO DECOUPLING TEMPERATURE

2012 ◽  
Vol 27 (32) ◽  
pp. 1250187
Author(s):  
S. C. İNAN ◽  
M. KÖKSAL
Keyword(s):  
Lagrangian Model ◽  
Electromagnetic Properties ◽  
Beyond The Standard Model ◽  
Ultrahigh Energy ◽  
Qcd Phase Transition ◽  
Effective Lagrangian ◽  
Independent Analysis ◽  
The Standard Model ◽  
Model Independent ◽  
The Impact

We examine the impact of electromagnetic properties of neutrinos on the annihilation of relic neutrinos with ultrahigh energy cosmic neutrinos for the [Formula: see text] process. For this process, photon–neutrino decoupling temperature is calculated via effective Lagrangian model beyond the standard model. We find that photon–neutrino decoupling temperature can be importantly reduced below the QCD phase transition with the model independent analysis defining electromagnetic properties of neutrinos.

General Model Independent Searches for Physics Beyond the Standard Model

2020 ◽  
Author(s):  
Saranya Samik Ghosh ◽  
Thomas Hebbeker ◽  
Arnd Meyer ◽  
Tobias Pook
Keyword(s):  
Standard Model ◽  
General Model ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Model Independent
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