arXiv subjects

Tomas Blazek

Publications and source records attributed to Tomas Blazek.

10 recordsLinked to original sources

arXiv2025

Minimal effective theory for leptogenesis, dark matter, and neutrino masses

We study the phenomenology of choosing a minimal set of effective operators simultaneously generating the dark matter relic density and matter-antimatter asymmetry of the universe. Neutrino masses are obtained in a specific case of baryogenesis via leptogenesis. We find that only two new particles -- a heavy unstable fermion and a light dark matter scalar -- need to be included in addition to the Standard Model particle content.

hep-ph↗

arXiv2001

E_6 unification model building III. Clebsch-Gordan coefficients in E_6 tensor products of the 27 with higher dimensional representations

$E_6$ is an attractive group for unification model building. However, the complexity of a rank 6 group makes it non-trivial to write down the structure of higher dimensional operators in an $E_6$ theory in terms of the states labeled by quantum numbers of the Standard Model gauge group. In this paper, we show the results of our computation of the Clebsch-Gordan coefficients for the products of the {\bf 27} with irreducible representations of higher dimensionality: ${\bf 78}$, ${\bf 351}$, ${\bf 351^\prime}$, ${\bf \ol{351}}$, and ${\bf \ol{351^\prime}}$. Application of these results to $E_6$ model building involving higher dimensional operators is straightforward.

hep-ph↗

arXiv2000

E_6 unification model building II. Clebsch-Gordan coefficients of 78$\otimes$78

We have computed the Clebsch-Gordan coefficients for the product (000001) $\otimes$ (000001), where (000001) is the adjoint 78-dimensional representation of $E_6$. The results are presented for the dominant weights of the irreducible representations in this product. As a simple application we express the singlet operator in $ 27 \otimes 78 \otimes \bar{27}$ in terms of multiplets of the Standard Model gauge group.

hep-ph↗

arXiv1999

Muon g-2 in the MSSM constrained by simple SO(10) SUSY GUT

We show that the best fits of the MSSM constrained by a simple SO(10) SUSY GUT are consistent with the present data on the muon anomalous magnetic moment. The best fits assume rather large values of tan$β\approx 50$, and in our analysis they are not {\em a priori} correlated in any way, directly or indirectly, with the experimental limit on $a_μ$. Regions in the SUSY parameter space, which are currently ruled out because of too large $a_μ^{SUSY}$, are already excluded in the global fit by excessive corrections to $m_b$, unacceptable $BR(b\to sγ)$, or direct experimental limits on sparticle masses. However, our results indicate that the accuracy expected in the ongoing E821 experiment at BNL will eventually turn the muon anomalous magnetic moment into a major constraint for this regime of the MSSM.

hep-ph↗

arXiv1999

$E_6$ unification model building I: Clebsch-Gordan coefficients of $27\otimes \ol{27}$

In an effort to develop tools for grand unified model building for the Lie group $E_6$, in this paper we present the computation of the Clebsch-Gordan coefficients for the product (100000) $\otimes$ (000010), where (100000) is the fundamental 27-dimensional representation of $E_6$ and (000010) is its charged conjugate. The results are presented in terms of the dominant weight states of the irreducible representations in this product. These results are necessary for the group analysis of $E_6$ operators involving also higher representations, which is the next step in this project. In this paper we apply the results to the construction of the operator ${\bf 27}^3$.

hep-ph↗

arXiv1997

$b \to sγ$ with Large tan$β$ in MSSM Analysis Constrained by a Realistic SO(10) Model

Study of the MSSM in large tan$β$ regime has to include correlations between the constraints presented by the low energy values of the b quark mass and BR($b \to sγ$). Both quantities receive SUSY contributions enhanced by tan$β$ and have a major impact on the MSSM analysis. Here we summarize the results of such a study constrained by a complete SO(10) model. The dominant effects to the analysis come from third generation Yukawa couplings and a GUT threshold to $α_s$. We show that a small negative GUT correction to $α_s$ accommodates $α_s(M_Z) \leq 0.118$ and $δm_b^{SUSY} > 0$. The latter quantity being positive then opens up two options to fit the measured rate for $b \to sγ$. The two distinct fits differ by the overall sign of the amplitude for this process. They work equally well in complementary regions of the allowed SUSY parameter space. We show plots of the partial contributions to the coefficient $C_7(M_Z)$ in the ($m_0,M_{1/2}$) plane in each of these best fits. We conclude that an attractive SO(10)-derived regime of the MSSM remains a viable option.

hep-ph↗

arXiv1997

Global Analysis of Electroweak Data in SUSY GUTs

A $χ^2$ analysis of several SUSY GUTs recently discussed in the literature is presented. We obtain global fits to electroweak data, which include gauge couplings, gauge boson masses, BR($b\to sγ$) and masses of fermions of all three generations and their mixing angles. Thus we are able to test gauge unification, radiative electroweak symmetry breaking, SUSY sector (- in the context of supergravity induced SUSY breaking) and the Yukawa sector in each particular model self-consistently. One of the models studied provides a very good fit with $χ^2 \sim 1$ for 3 degrees of freedom, in a large region of the allowed SUSY parameter space. The Yukawa sector works so well in this case that the analysis ends up testing the MSSM constrained by unification. Adopting this point of view, in the second part of this talk we focus on the details of the fit for BR($b\to sγ$) and discuss the correlations among $δm_b^{SUSY}$, $α_s(M_Z)$ and a GUT threshold to $α_s(M_G)$. We conclude that an attractive SO(10)-derived regime of the MSSM remains a viable option.

hep-ph↗

arXiv1996

A Global chi^2 Analysis of Electroweak Data in SO(10) SUSY GUTs

We present the details of a global $χ^2$ analysis of electroweak data, including fermion masses and mixing angles, in SO(10) SUSY GUTs. Just as precision electroweak data is used to test the Standard Model, the well determined Standard Model parameters are the precision electroweak data for testing theories beyond the Standard Model. In this paper we use the latest experimentally measured values for these parameters. We study several models discussed in the literature. One of these models provides an excellent fit to the low energy data with $χ^2 \sim 1$ for 3 degrees of freedom. We present graphs of constant $χ^2$ contours as functions of position in soft SUSY breaking parameter space, as well as our predictions for a few selected points in parameter space. We also study the sensitivity of our results to changes in various parameters. Finally, we discuss the consequences of our work in the context of a general MSSM analysis at the Z scale.

hep-ph↗

arXiv1996

A Global $χ^2$ Analysis of Electroweak Data (including Fermion Masses and Mixing Angles) in SO(10) SUSY GUTs

We present a global $χ^2$ analysis of electroweak data, including fermion masses and mixing angles, in SO(10) SUSY GUTs. Just as precision electroweak data is used to test the Standard Model, the well determined Standard Model parameters are the precision electroweak data for testing theories beyond the Standard Model. In this talk we use the latest experimentally measured values for these parameters. We study several models discussed in the literature. One of these models provides an excellent fit to the low energy data with $χ^2 \sim 1$ for 3 degrees of freedom. We present our predictions for a few selected points in parameter space.

hep-ph↗

arXiv1995

Finite Supersymmetric Threshold Corrections to CKM Matrix Elements in the Large $tanβ$ Regime

We evaluate the finite 1-loop threshold corrections, proportional to $tanβ$, to the down quark mass matrix. These result in corrections to down quark masses and to Cabibbo-Kobayashi-Maskawa [CKM] matrix elements. The corrections to CKM matrix elements are the novel feature of this paper. For grand unified theories with large $\tanβ$ these corrections may significantly alter the low energy predictions of four of the CKM matrix elements and the Jarlskog parameter J, a measure of CP violation. The angles $α,\: β$ and $γ$ of the unitarity triangle and the ratio $|{V_{ub} \over V_{cb}}|$, however, are not corrected to this order. We also discuss these corrections in the light of recent models for fermion masses. Here the corrections may be useful in selecting among the various models. Moreover, if one model fits the data, it will only do so for a particular range of SUSY parameters.

hep-ph↗