scholarly journals Origin and phenomenology of weak-doublet spin-1 bosons

2011 ◽  
Vol 703 (5) ◽  
pp. 593-598 ◽  
Author(s):  
M.V. Chizhov ◽  
Gia Dvali
Keyword(s):  
Weak Doublet

scholarly journals THE LIMITS OF CUSTODIAL SYMMETRY

2010 ◽  
Vol 25 (27n28) ◽  
pp. 5082-5096
Author(s):  
R. SEKHAR CHIVUKULA ◽  
ROSHAN FOADI ◽  
ELIZABETH H. SIMMONS ◽  
STEFANO DI CHIARA
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
Quark Mass ◽  
Electroweak Symmetry ◽  
Top Quark Mass ◽  
Particle Content ◽  
Dirac Mass ◽  
The Standard Model ◽  
Custodial Symmetry ◽  
Weak Doublet

We introduce a toy model implementing the proposal of using a custodial symmetry to protect the [Formula: see text] coupling from large corrections. This "doublet-extended standard model" adds a weak doublet of fermions (including a heavy partner of the top quark) to the particle content of the standard model in order to implement an O(4) × U(1)X ~ SU(2)L × SU(2)R × PLR × U(1)X symmetry in the top-quark mass generating sector. This symmetry is softly broken to the gauged SU(2)L × U(1)Y electroweak symmetry by a Dirac mass M for the new doublet; adjusting the value of M allows us to explore the range of possibilities between the O(4)-symmetric (M → 0) and standard-model-like (M → ∞) limits.

STUDY OF SITE GEOMETRY OF THE Sn CATIONS IN THE Sn-ADDED Tl-Pb(1223) SUPERCONDUCTING SYSTEM USING MÖSSBAUER AND AUGER EMISSION TECHNIQUES

1999 ◽  
Vol 13 (23) ◽  
pp. 2887-2893
Author(s):  
KAMLESH KUMARI ◽  
R. K. SINGHAL ◽  
K. B. GARG ◽  
E. M. BAGGIO-SAITOVICH ◽  
SOUZA AZAVEDO ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Major Part ◽  
Mössbauer Spectra ◽  
Mossbauer Spectra ◽  
Doublet Line ◽  
Minor Part ◽  
A Minor ◽  
Tetravalent State ◽  
Weak Doublet

The addition of Sn in Tl,Pb(1223) ( Tl 0.5 Pb 0.5 Sn x Sr 1.6 Ca 2.4 Cu 3 O y) has been investigated using AES and Mössbauer Emission techniques to probe the valence and site geometry of Sn cations. It was found that Sn is present in tetravalent state in the compound at two sites with differing weights. The major part of the tin resides inside the grain and a minor part (weak doublet line in Mossbauer spectra) represents the contribution from the tin at the grain boundary.

scholarly journals Are the CKM anomalies induced by vector-like quarks? Limits from flavor changing and Standard Model precision tests

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
B. Belfatto ◽  
Z. Berezhiani
Keyword(s):  
Standard Model ◽  
Decay Rate ◽  
Hadronic Decay ◽  
Kaon Decays ◽  
Parameter Spaces ◽  
Ckm Matrix ◽  
Flavor Changing ◽  
Beta Decays ◽  
Weak Doublet

Abstract Recent high precision determinations of Vus and Vud indicate towards anomalies in the first row of the CKM matrix. Namely, determination of Vud from beta decays and of Vus from kaon decays imply a violation of first row unitarity at about 3σ level. Moreover, there is tension between determinations of Vus obtained from leptonic Kμ2 and semileptonic Kℓ3 kaon decays. These discrepancies can be explained if there exist extra vector-like quarks at the TeV scale, which have large enough mixings with the lighter quarks. In particular, extra vector-like weak singlets quarks can be thought as a solution to the CKM unitarity problem and an extra vector-like weak doublet can in principle resolve all tensions. The implications of this kind of mixings are examined against the flavour changing phenomena and SM precision tests. We consider separately the effects of an extra down-type isosinglet, up-type isosinglet and an isodoublet containing extra quarks of both up and down type, and determine available parameter spaces for each case. We find that the experimental constraints on flavor changing phenomena become more stringent with larger masses, so that the extra species should have masses no more than few TeV. Moreover, only one type of extra multiplet cannot entirely explain all the discrepancies, and some their combination is required, e.g. two species of isodoublet, or one isodoublet and one (up or down type) isosinglet. We show that these scenarios are testable with future experiments. Namely, if extra vector-like quarks are responsible for CKM anomalies, then at least one of them should be found at scale of few TeV, and anomalous weak isospin violating Z-boson couplings with light quarks should be detected if the experimental precision on Z hadronic decay rate is improved by a factor of 2 or so.

scholarly journals S AND T PARAMETERS IN THE FERMION CONDENSATE MODEL

2009 ◽  
Vol 24 (29) ◽  
pp. 2331-2344 ◽  
Author(s):  
G. CYNOLTER ◽  
E. LENDVAI ◽  
G. PÓCSIK
Keyword(s):  
Standard Model ◽  
Positive Contribution ◽  
Electroweak Symmetry ◽  
Mixing Angle ◽  
Composite Higgs ◽  
The Standard Model ◽  
The Masses ◽  
Electroweak Precision ◽  
Weak Doublet ◽  
Heavy Higgs Boson

We calculate the oblique electroweak corrections and confront them with the experiments in a composite Higgs version of the standard model. A vector-like weak doublet and a singlet fermion are added to the standard model without elementary Higgs. Due to quartic coupling, there is a mixing between the components of the new fields triggering electroweak symmetry breaking. The Peskin–Takeuchi S and T electroweak parameters are presented. The new sector of vector-like fermions is slightly constrained, T gives an upper bound on the mixing angle of the new fermions, which is already constrained by self-consistent gap-equations. S gives no constraints on the masses. This extension can give a positive contribution to T, allowing for a heavy Higgs boson in electroweak precision tests of the Standard Model.

scholarly journals Probing the Goldstone equivalence theorem in heavy weak doublet decays

2016 ◽  
Vol 93 (5) ◽  
Author(s):  
Bhaskar Dutta ◽  
Yu Gao ◽  
David Sanford ◽  
Joel W. Walker
Keyword(s):  
Equivalence Theorem ◽  
Weak Doublet

Study ofbcouplings in the standard weak doublet model and in models without atquark

1981 ◽  
Vol 24 (5) ◽  
pp. 1328-1342 ◽  
Author(s):  
V. Barger ◽  
W. Y. Keung ◽  
R. J. N. Phillips
Keyword(s):  
Doublet Model ◽  
Weak Doublet
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