scholarly journals Effects of the FCNC Couplings in Production of New Heavy Quarks withinZ′Models at the LHC

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
V. Çetinkaya ◽  
V. Arı ◽  
O. Çakır
Keyword(s):  
Cross Sections ◽  
Neutral Current ◽  
Top Quarks ◽  
Heavy Quarks ◽  
Flavor Changing ◽  
Heavy Quark Mass ◽  
Flavor Changing Neutral Current ◽  
Single Production ◽  
The Cross ◽  
Flavor Tagging

We study the flavor changing neutral current couplings of new heavy quarks through theZ′models at the LHC. We calculate the cross sections for the signal and the corresponding standard model background processes. Considering the present limits on the mass of new heavy quarks and theZ′boson, we performed an analysis to investigate the parameter space (mixing and mass) through differentZ′models. For FCNC mixing parameterx=0.1and theZ′massMZ′=2000 GeV and new heavy quark massmt′=700 GeV at the LHC withs=13 TeV, we find the cross section for single production of new heavy quarks associated with top quarks as5.8 fb,3.3 fb,1.5 fb, and1.2 fb within theZη′,Zψ′,ZLP′, andZχ′models, respectively. It is shown that the sensitivity would benefit from the flavor tagging.

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 A UNIFIED APPROACH TO NNLO SOFT AND VIRTUAL CORRECTIONS IN ELECTROWEAK, HIGGS, QCD, AND SUSY PROCESSES

2004 ◽  
Vol 19 (11) ◽  
pp. 1793-1821 ◽  
Author(s):  
NIKOLAOS KIDONAKIS
Keyword(s):  
Cross Sections ◽  
Neutral Current ◽  
New Physics ◽  
Higgs Bosons ◽  
Unified Approach ◽  
Threshold Resummation ◽  
Flavor Changing ◽  
Anomalous Dimensions ◽  
Vector Bosons ◽  
Flavor Changing Neutral Current

I present a unified approach to calculating the next-to-next-to-leading order (NNLO) soft and virtual QCD corrections to cross-sections for electroweak, Higgs, QCD, and SUSY processes. I derive master formulas that can be used for any of these processes in hadron–hadron and lepton–hadron collisions. The formulas are based on a unified threshold resummation formalism and can be applied to both total and differential cross-sections for processes with either simple or complex color flows and for various factorization schemes and kinematics. As a test of the formalism, I rederive known NNLO results for Drell–Yan and Higgs production, deep inelastic scattering, and W+γ production, and I obtain expressions for several two-loop anomalous dimensions and other quantities needed in next-to-next-to-leading-logarithm (NNLL) resummations. I also present new results for the production of supersymmetric charged Higgs bosons; massive electroweak vector bosons; photons; heavy quarks in lepton–hadron and hadron–hadron collisions and in flavor-changing neutral current processes; jets; and squarks and gluinos. The NNLO soft and virtual corrections are often dominant, especially near threshold, and they reduce the scale dependence of the cross-section. Thus, a unified approach to these corrections is important in the search for new physics at present and future colliders.

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 Search for the flavor-changing neutral current decay D0→μ+μ− with the HERA-B detector

2004 ◽  
Vol 596 (3-4) ◽  
pp. 173-183 ◽  
Author(s):  
I. Abt ◽  
M. Adams ◽  
H. Albrecht ◽  
A. Aleksandrov ◽  
V. Amaral ◽  
...  
Keyword(s):  
Neutral Current ◽  
Current Decay ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current ◽  
Neutral Current Decay

scholarly journals SCALAR DARK MATTER EFFECTS IN HIGGS AND TOP QUARK DECAYS

2007 ◽  
Vol 22 (25n28) ◽  
pp. 2121-2129 ◽  
Author(s):  
XIAO-GANG HE ◽  
HO-CHIN TSAI ◽  
TONG LI ◽  
XUE-QIAN LI
Keyword(s):  
Dark Matter ◽  
Top Quark ◽  
Neutral Current ◽  
Higgs Doublet ◽  
Tree Level ◽  
Flavor Changing ◽  
Higgs Decay ◽  
Dark Matter Relic Density ◽  
Flavor Changing Neutral Current ◽  
Two Higgs Doublet Model

We study possible observational effects of scalar dark matter, the darkon D, in Higgs h and top quark t decay processes, h → DD and t → cDD in the minimal Standard Model (SM) and its two Higgs doublet model (THDM) extension supplemented with a SM singlet darkon scalar field D. We find that the darkon D can have a mass in the range of sub-GeV to several tens of GeV, interesting for LHC and ILC colliders, to produce the required dark matter relic density. In the SM with a darkon, t → cDD only occurs at loop level giving a very small rate, while the rate for Higgs decay h → DD can be large. In THDM III with a darkon, where tree level flavor changing neutral current (FCNC) interaction exists, a sizable rate for t → cDD is also possible.

scholarly journals Flavor changing neutral current processes in a reduced minimal scalar sector

2014 ◽  
Vol 29 (32) ◽  
pp. 1450173 ◽  
Author(s):  
D. Cogollo ◽  
Farinaldo S. Queiroz ◽  
P. Vasconcelos
Keyword(s):  
Gauge Boson ◽  
Neutral Current ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current ◽  
Individual Contributions ◽  
The Individual ◽  
Meson System ◽  
Scalar Sector

In this work, we overhaul previous studies of Flavor Changing Neutral Current processes in the context of the Reduced Minimal 3-3-1 (RM331) model. We sift the individual contributions from the CP-even scalars and the Z′ gauge boson using two different parametrizations schemes and compare our results with current measurements. In particular, studying the [Formula: see text] meson system we find the most stringent bounds in the literature on this model, namely [Formula: see text] and [Formula: see text].

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.

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