scholarly journals Structure of flavor changing Goldstone boson interactions

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Jin Sun ◽  
Yu Cheng ◽  
Xiao-Gang He
Keyword(s):  
Symmetry Breaking ◽  
Model Building ◽  
Neutral Current ◽  
Goldstone Boson ◽  
New Physics ◽  
Majorana Neutrino ◽  
Neutrino Masses ◽  
Type I ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current

Abstract General flavor changing Goldstone boson (GB) interactions with fermions from a spontaneous global U(1)G symmetry breaking are discussed. This GB may be the Axion, solving the strong QCD CP problem, if there is a QCD anomaly for the assignments of quarks U(1)G charge. Or it may be the Majoron, producing seesaw Majorana neutrino masses by lepton number violation, if the symmetry breaking scale is much higher than the electroweak scale. It may also, in principle, play the roles of Axion and Majoron simultaneously as far as providing solution for the strong CP problem and generating a small Majorana neutrino masses are concerned. Great attentions have been focused on flavor conserving GB interactions. Recently flavor changing Axion and Majoron models have been studied in the hope to find new physics from rare decays in the intensity frontier. In this work, we will provide a systematic model building aspect study for flavor changing neutral current (FCNC) GB interactions in the fermion sectors, or separately in the quark, charged lepton and neutrino sectors and will identify in detail the sources of FCNC interactions in a class of beyond standard model with a spontaneous global U(1)G symmetry breaking. We also provide a general proof of the equivalence of using physical GB components and GB broken generators for calculating GB couplings to two gluons and two photons, and discuss some issues related to spontaneous CP violation models. Besides, we will also provide some details for obtaining FCNC GB interactions in several popular models, such as the Type-I, -II, -III seesaw and Left-Right symmetric models, and point out some special features in these models.

scholarly journals PREDICTIONS FOR $B \to \tau \bar{\mu} + \mu \bar{\tau}$

2013 ◽  
Vol 28 (31) ◽  
pp. 1350153 ◽  
Author(s):  
DRIS BOUBAA ◽  
ALAKABHA DATTA ◽  
MURUGESWARAN DURAISAMY ◽  
SHAABAN KHALIL
Keyword(s):  
Standard Model ◽  
Supersymmetric Standard Model ◽  
Minimal Supersymmetric Standard Model ◽  
Neutral Current ◽  
Higgs Sector ◽  
New Physics ◽  
Flavor Changing ◽  
Clear Sign ◽  
Flavor Changing Neutral Current ◽  
Extended Higgs Sector

The observation of [Formula: see text] at present experiments would be a clear sign of new physics. In this paper, we calculate this process in an extended Higgs sector framework where the decay is mediated by the exchange of spin zero particle with flavor changing neutral current couplings. If we identify the scalar with the newly discovered state at LHC with a mass ~125 GeV then we find that, after imposing all experimental constraints, the [Formula: see text] can be as high as ~10-6 and [Formula: see text] can be as high as ~10-7. We also calculate this process in the minimal supersymmetric standard model and find the [Formula: see text] is typically of the order ~10-8.

scholarly journals A Mathematica package for calculation of one-loop penguins in FCNC processes

2015 ◽  
Vol 26 (04) ◽  
pp. 1550042 ◽  
Author(s):  
Alexander Vadimovich Bednyakov ◽  
Şükrü Hanif Tanyıldızı
Keyword(s):  
Neutral Current ◽  
New Physics ◽  
Feynman Diagrams ◽  
Tree Level ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current ◽  
Physics Model ◽  
The One ◽  
Effective Operators

In this work, we present a Mathematica package Peng4BSM@LO which calculates the contributions to the Wilson Coefficients of certain effective operators originating from the one-loop penguin Feynman diagrams. Both vector and scalar external legs are considered. The key feature of our package is the ability to find the corresponding expressions in almost any New Physics model which extends the SM and has no flavor changing neutral current (FCNC) transitions at the tree level.

scholarly journals RADIATIVE AND ELECTROWEAK RARE B DECAYS

2004 ◽  
Vol 19 (06) ◽  
pp. 934-948 ◽  
Author(s):  
M. NAKAO
Keyword(s):  
B Meson ◽  
Dominant Role ◽  
Rare Decay ◽  
Neutral Current ◽  
New Physics ◽  
Beyond The Standard Model ◽  
B Meson Decays ◽  
Meson Decays ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current

This report summarizes the latest experimental results on radiative and electroweak rare B meson decays. These rare decay processes proceed through the Flavor-Changing-Neutral-Current processes, and thus are sensitive to the postulated new particles in the theories beyond the Standard Model. Experiments at e+e- colliders, Belle, BaBar and CLEO, have been playing the dominant role, while the CDF and D0 experiments have just started to provide new results from Tevatron Run-II. The most significant achievement is the first observation of the decay B→K*ℓ+ℓ-, which opens a new window to search for new physics in B meson decays.

scholarly journals Study of electroweak penguin B decays at Belle II experiment

2021 ◽  
Vol 2145 (1) ◽  
pp. 012018
Author(s):  
J Ineead ◽  
S Nishida ◽  
B Asavapibhop ◽  
N Suwonjandee
Keyword(s):  
Branching Fraction ◽  
Neutral Current ◽  
New Physics ◽  
Lepton Flavor ◽  
Flavor Changing ◽  
Penguin Diagram ◽  
The Status ◽  
Flavor Changing Neutral Current ◽  
Belle Ii ◽  
Exclusive Decay

Abstract The electroweak b → sll (l = e, µ) transition is a flavor-changing neutral current process that mediates through a one-loop penguin diagram. The decay is considered to be a good probe for the New Physics as particles predicted in the beyond Standard Model theories can enter into the loop. The exclusive decay B → K (*) l + l − was first observed by the Belle experiment and it provides many observables such as the branching fraction, CP asymmetry, forward-backward asymmetry, and other angular observables. Recently, the LHCb experiment has reported some clue of a lepton flavor universality violation from the branching fraction ratio of the B → Kµ + µ − and B → Ke + e − decays. In this presentation, we report the status of the B → Kl + l − decay analysis at the Belle II experiment which started the data taking in 2019. We also, present an activity at the Belle II Chulalongkorn University group where we study the B → KJ/ψ decay which has the same topology as the B → Kl + l − .

scholarly journals ISOSPIN SYMMETRY BREAKING IN B → K*γ DECAY DUE TO AN EXTRA GENERATION OF VECTOR QUARKS

2005 ◽  
Vol 20 (27) ◽  
pp. 6229-6240 ◽  
Author(s):  
MOHAMMAD R. AHMADY ◽  
FARRUKH CHISHTIE
Keyword(s):  
Symmetry Breaking ◽  
Neutral Current ◽  
Tree Level ◽  
Additional Contribution ◽  
Isospin Symmetry ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current ◽  
Acceptable Model ◽  
Isospin Symmetry Breaking ◽  
Zero Tree

The extra contributions due to an extra generation of vector-like quarks to the isospin symmetry breaking observable associated with the radiative B → K*γ decay is obtained. It is shown that this additional contribution is sensitive to the nonunitarity parameter Usb, which is a measure of the the strength of the non-zero tree-level flavor changing neutral current in this model. The significance of this result is that, once accurate experimental results on the isospin asymmetry becomes available, one can constrain the Usb independent of the mass of the extra quarks and so a much more stringent acceptable model parameter space could be obtained.

scholarly journals Probing the anomalous tqγ couplings through single top production at the future lepton–hadron colliders

2019 ◽  
Vol 34 (36) ◽  
pp. 1950298 ◽  
Author(s):  
E. Alici ◽  
M. Köksal
Keyword(s):  
Cross Sections ◽  
Top Quark ◽  
Neutral Current ◽  
New Physics ◽  
Main Reaction ◽  
Flavor Changing ◽  
Effective Lagrangian ◽  
Quark Flavor ◽  
The Future ◽  
Flavor Changing Neutral Current

The measurements of the top quark flavor changing neutral current interactions are one of the most important goals of the top quark physics program in the present and the future collider experiments. These measurements provide direct information on nonstandard interactions of the top quark. Within the framework of new physics beyond the Standard Model, these interactions can be defined by an effective Lagrangian. In this study, we have investigated the potential of the future [Formula: see text] colliders on the top quark flavor changing neutral current interactions through the subprocesses [Formula: see text], where [Formula: see text]. These subprocesses have been produced through the main reaction [Formula: see text] at the LHC-[Formula: see text], the FCC-[Formula: see text] and the SPPC-[Formula: see text]. For the main reaction, the total cross-sections have been calculated as a function of the anomalous [Formula: see text] couplings. In addition, sensitivities on [Formula: see text] at 95% Confidence Level have been calculated. We obtain that the best constraints on [Formula: see text] are at the order of [Formula: see text] which is four orders of magnitude better than the LHC’s experimental results.

scholarly journals Top and beauty synergies in SMEFT-fits at present and future colliders

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Stefan Bißmann ◽  
Cornelius Grunwald ◽  
Gudrun Hiller ◽  
Kevin Kröninger
Keyword(s):  
Effective Field Theory ◽  
Top Quark ◽  
Neutral Current ◽  
New Physics ◽  
Effective Field ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current ◽  
Three Stages ◽  
Belle Ii ◽  
Existing Data

Abstract We perform global fits within Standard Model Effective Field Theory (SMEFT) combining top-quark pair production processes and decay with b → s flavor changing neutral current transitions and Z → $$ b\overline{b} $$ b b ¯ in three stages: using existing data from the LHC and B-factories, using projections for the HL-LHC and Belle II, and studying the additional new physics impact from a future lepton collider. The latter is ideally suited to directly probe ℓ+ℓ− → $$ t\overline{t} $$ t t ¯ transitions. We observe powerful synergies in combining both top and beauty observables as flat directions are removed and more operators can be probed. We find that a future lepton collider significantly enhances this interplay and qualitatively improves global SMEFT fits.

Sign in / Sign up

Export Citation Format

Share Document