Supersymmetry at the electroweak scale Chankowski, Piotr H.; Pokorski, Stefan
Nuclear physics. Section B, Proceedings supplement,
January 1997, 1997-1-00, Letnik:
52, Številka:
1-2
Journal Article
Recenzirano
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The simplest interpretation of the global success of the Standard Model is that new physics decouples well above the electroweak scale. Supersymmetric extension of the Standard Model offers the ...possibility of light chargino and the right-handed stop (with masses below Mz), and still maintaining the successful predictions of the Standard Model. The value of Rb can then be enhanced up to ∼ 0.218 (the Standard Model value is ∼ 0.216). Light chargino and stop give important contribution to rare processes such as b → sγ, K¯0−K0 and B¯0−B0 mixing but consistency with experimental results is maintained in a large region of the parameter space. The exotic four-jet events reported by ALEPH (if confirmed) may constitute a signal for supersymmetry with such a light spectrum and with explicitly broken R—parity. Their interpretation as pair production of charginos with mc ∼ 60 GeV, with subsequent decay C→t˜Rb→dsb(wheremt˜∼55GeV) leads to signatures very close to the experimental observations.
Ce livre donne un état des récentes découvertes de monnaies de fouille en Méditerranée orientale dont celles faites en Égypte lors des fouilles sous-marines dans le delta du Nil en Égypte ou en Grèce ...sur les sites royaux de Macédoine. Une grande partie de ce matériel est inédite. L’ambition des auteurs est d’abord méthodologique : les monnaies de fouille sont des monnaies principalement perdues, souvent de faible valeur ou hors d’usage (décri, monnaies modifiées, fausses monnaies). L’objectif classique de leur étude est de fournir des marqueurs chronologiques aux archéologues, d’enrichir les corpus monétaires ou d’étudier la circulation. En réalité, elles offrent bien d’autres possibilités à la recherche (étude des phases de circulation et de décri, des pratiques monétaires, histoire économique, histoire des pratiques sociales, etc.), qu’elles soient trouvées en groupe ou isolées, dès lors qu’elles sont remises en contexte archéologique, de concert avec les autres artefacts, notamment céramiques.
Eur.Phys.J.C50:919-933,2007 We consider the electroweak theory with an additional Higgs triplet at one
loop using the hybrid renormalization scheme based on $\alpha_{\rm EM}$, $G_F$
and $M_Z$ as ...input observables. We show that in this scheme loop corrections
can be naturally split into the Standard Model part and corrections due to
``new physics''. The latter, however do not decouple in the limit of infinite
triplet mass parameter, if the triplet trilinear coupling to SM Higgs doublets
grows along with the the triplet mass. In electroweak observables computed at
one loop this effect can be attributed to radiative generation in this limit of
a nonvanishing vacuum expectation value of the triplet. We also point out that
whenever tree level expressions for the electroweak observables depend on
vacuum expectation values of scalar fields other than the Standard Model Higgs
doublet, tadpole contribution to the ``oblique'' parameter $T$ should in
principle be included. In the Appendix the origin of nondecoupling is discussed
on the basis of symmetry principles in a simple scalar field theory.
Eur.Phys.J.C33:123-136,2004 We investigate the potential effects of the scalar flavour changing neutral
currents that are generated e.g. in supersymmetry with $\tan\beta\gg1$ in the
$b\to sl^+l^-$ ...transitions. Using the experimental upper limit on
$BR(B^0_s\to\mu^+\mu^-)$ we place stringent model independent constraints on
the impact these currents may have on the rates $BR(B\to X_s\mu^+\mu^-)$ and
$BR(B\to K\mu^+\mu^-)$. We find that in the first case, contrary to the claim
made recently in the literature, the maximal potential effects are always
smaller than the uncertainty of the Standard Model NNLO prediction, that is of
order 5-15%. In the second case, the effects can be large but the experimental
errors combined with the unsettled problems associated with the relevant
formfactors do not allow for any firm conclusion about the detectability of a
new physics signal in this process. In supersymmetry the effects of the scalar
flavour changing neutral currents are further constrained by the experimental
lower limit on the $B^0_s$-$\bar B^0_s$ mass difference, so that most likely no
detectable signal of the supersymmetry generated scalar flavour changing
neutral currents in processes $B\to X_s\mu^+\mu^-$ and $B\to K\mu^+\mu^-$ is
possible.
Phys.Lett. B570 (2003) 198-204 We make a simple observation that if one of the right-chiral neutrinos is
very heavy or its Yukawa couplings to the standard lepton doublets are
negligible, so that it ...effectively decouples from the see-saw mechanism, the
prediction for the baryon asymmetry of the Universe resulting from leptogenesis
depends, apart from the masses $M_1$ and $M_2$ of the remaining two
right-chiral neutrinos, only on the element $\YY{22}$ of the neutrino Yukawa
coupling. For $M_2\simgt10M_1$ the lower bound on $M_1$ and also on $T_{\rm
reh}$, resulting from the requirement of 'successful leptogenesis' is then
significantly increased compared to the one computed recently by Buchm\"uller
{\it et al.} in the most general case. Within the framework of thermal
leptogenesis, the only way to lower this limit is then to allow for
sufficiently small mass difference $M_2-M_1$.
Eur.Phys.J.C47:187-205,2006 We consider the electroweak theory with an additional neutral vector boson
$Z^\prime$ at one loop. We propose a renormalization scheme which makes the
decoupling of heavy ...$Z^\prime$ effects manifest. The proposed scheme justifies
the usual procedure of performing fits to the electroweak data by combining the
full SM loop corrections to observables with the tree level corrections due to
the extended gauge structure. Using this scheme we discuss in the model with
extra an $U(1)^\prime$ group factor 1-loop results for the $\rho$ parameters
defined in several different ways.
Acta Phys.Polon.B33:2329-2354,2002 Recent development in exploring flavour dynamics in the supersymmetric
extension of the Standard Model is reviewed. Emphasis is put on possible
interesting effects ...in b-physics arising for large values of tan beta both in
the case of minimal flavour violation and in the case of flavour violation
originating in the sfermion sector. The importance of the flavour changing
neutral Higgs boson couplings generated by the scalar penguin diagrams and
their role in the interplay of neutral B-meson mixing and B^0_{d,s} --> mu^+
mu^- decays is discussed. It is pointed out that observation of the B^0_d -->
mu^+ mu^- decay with BR at the level $\simgt 3 X 10^{-8}$ would be a strong
indication of nonminimal flavour violation in the quark sector. Possible impact
of flavour violation in the slepton sector on neutrino physics is also
discussed.
Eur.Phys.J.C23:249-258,2002 We compute the low energy threshold corrections to neutrino masses and mixing
in the Standard Model (SM) and its minimal supersymmetric version, using the
effective theory ...technique. We demonstrate that they stabilize the
renormalization group (RG) running with respect to the choice of the scale to
which the RG equation is integrated. This confirms the correctness of the
recent re-derivation of the RGE for the SM in hep-ph/0108005. The explicit
formulae for the low energy threshold corrections corrections can be applied to
specific models of neutrino masses and mixing.
Int.J.Mod.Phys.A17:575-614,2002 Contents: 1. Introduction 2. Fermion masses and mixing 3. Neutrino masses in
the effective theory 4. Quantum corrections from the renormalization group
evolution 4.1. ...RG equations for the CKM matrix 4.2. RG equations for neutrino
masses and mixing angles 4.3. Evolution of the neutrino masses 4.4. Mixing of
two neutrinos 4.5 Mixing of three neutrinos and fixed points 5. Low energy
threshold corrections 5.1. Threshold corrections in the SM 5.2. Threshold
corrections in the MSSM 5.2.1. Three-fold degeneracy and flavour diagonal
corrections 5.2.2. Three-fold degeneracy and flavour non-diagonal corrections
5.2.3. Two-fold degeneracy and threshold corrections 6. Conclusions, Appendix
A, Appendix B, References.
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