arXiv subjects

T. Blazek

Publications and source records attributed to T. Blazek.

14 recordsLinked to original sources

arXiv2018

Search for $K^{+}\rightarrowπ^{+}ν\overlineν$ at NA62

$K^{+}\rightarrowπ^{+}ν\overlineν$ is one of the theoretically cleanest meson decay where to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN SPS is designed to measure the branching ratio of this decay with 10\% precision. NA62 took data in pilot runs in 2014 and 2015 reaching the final designed beam intensity. The quality of 2015 data acquired, in view of the final measurement, will be presented.

hep-ex↗

arXiv2014

Prospects for $K^+ \to π^+ ν\bar{ ν}$ at CERN in NA62

The NA62 experiment will begin taking data in 2015. Its primary purpose is a 10% measurement of the branching ratio of the ultrarare kaon decay $K^+ \to π^+ ν\bar{ ν}$, using the decay in flight of kaons in an unseparated beam with momentum 75 GeV/c.The detector and analysis technique are described here.

hep-ex↗

arXiv2004

Electron to Muon Conversion in Electron-Nucleus Scattering as a Probe of Supersymmetry

We suggest that $e\to μ$ conversion in low-energy electron-nucleus scattering is a new and potentially observable indirect signal of supersymmetry and should be searched for in experiment. We estimate the rate for this process in a straightforward calculation taking into account the existing constraint from non-observation of the $μ\to eγ$ decay and find the cross-section to be $σ< 10^{-8} $fb.

hep-ph↗

arXiv2004

Best Fit Predictions for Flavour Violating Processes in MSSM Constrained by Unification

We study the Minimal Supersymmetric Standard Model (MSSM) constrained by unification assuming mSUGRA SUSY breaking. In particular this means that the three gauge couplings are unified at a {\it per cent} level, third generation yukawa couplings are unified at a $10 $% level, and at the unification scale $M_U\approx 10^{16}$ the SUSY breaking masses of squarks and sleptons are universal up to specific D-term contributions. At $M_U$ we also include right-handed neutrinos that are decoupled at their three respective scales. In a top-down global analysis we then find that there are two distinct best fits, primarily distinguished by the masses of the non-Standard Model Higgs states, and compute the predictions for flavour violating processes involving both leptons and quarks. The fit with the light Higgs spectrum is especially interesting with regards to the decay $B_s\to μ^+μ^-$. We note that the latter results go beyond what is called minimal flavour violation in the MSSM.

hep-ph↗

arXiv2003

Implications of $B_s\to μ^{+}μ^{-}$ in SO(10)-like Models

We examine the potentially very promising signal $B_s\to μ^{+}μ^{-}$ in supersymmetry with large $\tanβ$ in a {\em top-down} approach starting from the best fits of an SO(10)-like model studied recently. Our results go beyond minimal flavour violation investigated in previous works. We show that the absolute best fits provide a signal for $B_s\to μ^{+}μ^{-}$ at the borderline of the present limits and hence the ongoing search at the Tevatron will start having an impact on the global analysis of this class of SUSY models. We discuss the implications of a measurement of $B_s\to μ^{+}μ^{-}$ for restricting the parameter space of gauginos and sfermion masses, and of signals in other channels $B_{d,s}\to l^{+}+l^{-}$. We also discuss correlations of $B_s\to μ^{+}μ^{-}$ with the CP-odd Higgs mass, $\sin (β-α)$ and $b\to s γ$ in SO(10)-like models.

hep-ph↗

arXiv2003

Global Analysis of a Supersymmetric Pati-Salam Model

We perform a complete global phenomenological analysis of a realistic string-inspired model based on the supersymmetric Pati-Salam $SU(4)\times SU(2)_L \times SU(2)_R$ gauge group supplemented by a U(1) family symmetry, and present predictions for all observables including muon $g-2$, $τ\to μγ$, and the CHOOZ angle. Our analysis demonstrates the compatibility of such a model with all laboratory data including charged fermion masses and mixing angles, LMA MSW and atmospheric neutrino masses and mixing angles, and $b \to s γ$, allowing for small deviations from third family Yukawa unification. We show that in such models the squark and slepton masses may be rather light compared to similar models with exact Yukawa unification.

hep-ph↗

arXiv2002

Yukawa Unification in SO(10)

In simple SO(10) SUSY GUTs the top, bottom and tau Yukawa couplings unify at the GUT scale. A naive renormalization group analysis, neglecting weak scale threshold corrections, leads to moderate agreement with the low energy data. However it is known that intrinsically large threshold corrections proportional to $\tanβ\sim m_t(M_Z)/m_b(M_Z) \sim 50$ can nullify these $t, b$, $τ$ mass predictions. In this paper we turn the argument around. Instead of predicting fermion masses, we use the constraint of Yukawa unification and the observed values $M_t, m_b(m_b), M_τ$ to constrain SUSY parameter space. We find a narrow region survives for $μ> 0$ with $μ, M_{1/2} << m_{16}$, $A_0 \approx - 1.9 m_{16}$ and $m_{16} > 1200$ \gev. Demanding Yukawa unification thus makes definite predictions for Higgs and sparticle masses. In particular we find a light higgs with mass $m_h^0 = 114 \pm 5 \pm 3$ GeV and a light stop with $(m_{\tilde t_1})_{MIN} \sim 450$ GeV and $m_{\tilde t_1} << m_{\tilde b_1}$. In addition, we find a light chargino and a neutralino LSP. It is also significant that in this region of parameter space the SUSY contribution to the muon anomalous magnetic moment $a_μ^{SUSY} < 16 \times 10^{-10}$.

hep-ph↗

arXiv2002

The Beyond the Standard Model Working Group: Summary Report

Report of the "Beyond the Standard Model" working group for the Workshop `Physics at TeV Colliders', Les Houches, France, 21 May - 1 June 2001. It consists of 18 separate parts: 1. Preface; 2. Theoretical Discussion; 3. Numerical Calculation of the mSUGRA and Higgs Spectrum; 4. Theoretical Uncertainties in Sparticle Mass Predictions; 5. High Mass Supersymmetry with High Energy Hadron Colliders; 6. SUSY with Heavy Scalars at LHC; 7. Inclusive Study of MSSM in CMS; 8. Establishing a No-Lose Theorem for NMSSM Higgs Boson Discovery at the LHC; 9. Effects of Supersymmetric Phases on Higgs Production in Association with Squark Pairs in the Minimal Supersymmetric Standard Model; 10. Study of the Lepton Flavour Violating Decays of Charged Fermions in SUSY GUTs; 11. Interactions of the Goldstino Supermultiplet with Standard Model Fields; 12. Attempts at Explaining the NuTeV Observation of Di-Muon Events; 13. Kaluza-Klein States of the Standard Model Gauge Bosons: Constraints From High Energy Experiments; 14. Kaluza-Klein Excitations of Gauge Bosons in the ATLAS Detector; 15. Search for the Randall Sundrum Radion Using the ATLAS Detector; 16. Radion Mixing Effects on the Properties of the Standard Model Higgs Boson; 17. Probing Universal Extra Dimensions at Present and Future Colliders; 18. Black Hole Production at Future Colliders.

hep-ph↗

arXiv2002

Predictions for Higgs and SUSY spectra from SO(10) Yukawa Unification with mu > 0

We use $t, b, τ$ Yukawa unification to constrain SUSY parameter space. We find a narrow region survives for $μ> 0$ (suggested by \bsgam and the anomalous magnetic moment of the muon) with $A_0 \sim - 1.9 m_{16}$, $m_{10} \sim 1.4 m_{16}$, $m_{16} \sim 1200 -3000$ \gev and $μ, M_{1/2} \sim 100 - 500$ \gev. Demanding Yukawa unification thus makes definite predictions for Higgs and sparticle masses.

hep-ph↗

arXiv2001

Muon Anomalous Magnetic Moment and $τ\to μγ$ in a Realistic String-Inspired Model of Neutrino Masses

We discuss the lepton sector of a realistic string-inspired model based on the Pati-Salam $SU(4)\times SU(2)_L \times SU(2)_R$ gauge group supplemented by a U(1) family symmetry. The model involves third family Yukawa unification, predicts large $\tan β\sim 50$, and describes all fermion masses and mixing angles, including approximate bi-maximal mixing in the neutrino sector. Atmospheric neutrino mixing is achieved via a large 23 entry in the neutrino Yukawa matrix which can have important phenomenological effects. We find that the recent BNL result on the muon ($g-2$) can be easily accommodated in a large portion of the SUSY parameter space of this model. Over this region of parameter space the model predicts a CP-even Higgs mass near 115 GeV, and a rate for $τ\to μγ$ which is close to its current experimental limit.

hep-ph↗

arXiv2000

Neutrino Oscillations in an SO(10) SUSY GUT with U(2)xU(1)$^n$ Family Symmetry

In a previous paper we analyzed fermion masses (focusing on neutrino masses and mixing angles) in an SO(10) SUSY GUT with U(2)$\timesU(1)^n$ family symmetry. The model is "natural" containing all operators in the Lagrangian consistent with the states and their charges. With minimal family symmetry breaking vevs the model is also predictive giving a unique solution to atmospheric (with maximal $ν_μ\to ν_τ$ mixing) and solar (with SMA MSW $ν_e \to ν_s$ mixing) neutrino oscillations. In this paper we analyze the case of general family breaking vevs. We now find several new solutions for three, four and five neutrinos. For three neutrinos we now obtain SMA MSW, LMA MSW or vacuum oscillation solutions for solar neutrinos. In all three cases the atmospheric data is described by maximal $ν_μ\to ν_τ$ mixing. In the four and five neutrino cases, in addition to fitting atmospheric and solar data as before, we are now able to fit LSND data. All this is obtained with the additional parameters coming from the family symmetry breaking vevs; providing only minor changes in the charged fermion fits.

hep-ph↗

arXiv1999

Neutrino Oscillations in a Predictive SUSY GUT

In this letter we present a predictive SO(10) SUSY GUT with flavor symmetry U(2) \times U(1) which has several nice features. We are able to fit fermion masses and mixing angles, including recent neutrino data, with 9 parameters in the charged fermion sector and 4 in the neutrino sector. The flavor symmetry plays a preeminent role -- (i) The model is "natural" -- we include all terms allowed by the symmetry. It restricts the number of arbitrary parameters and enforces many zeros in the effective mass matrices. (ii) Flavor symmetry breaking from U(2) \times U(1) \to U(1) \to nothing generates the family hierarchy. It also constrains squark and slepton mass matrices, thus ameliorating flavor violation resulting from squark and slepton loop contributions. (iii) Finally, it naturally gives large angle $ν_μ- ν_τ$ mixing describing atmospheric neutrino oscillation data and small angle $ν_e - ν_{s}$ mixing consistent with the small mixing angle MSW solution to solar neutrino data.

hep-ph↗

arXiv1998

MSSM with Large tan$β$ Constrained by Minimal SO(10) Unification

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 minimal SO(10) unification. We show the best fits, in the $(m_0,M_{1/2})$ plane, obtained in the global analysis spanned over the gauge, Yukawa and SUSY parameter space at the unification scale. Two distinct fits describe the available low-energy data very well. The fits differ by the overall sign of the $b\to sγ$ decay amplitude. We conclude that an attractive SO(10)-derived regime of the MSSM remains a viable option.

hep-ph↗

arXiv1996

Supersymmetric Grand Unified Theories and Global Fits to Low Energy Data

We present a self-consistent $χ^2$ analysis of several supersymmetric (SUSY) grand unified theories recently discussed in the literature. We obtain global fits to low energy data, including gauge couplings, fermion masses and mixing angles, gauge boson masses and $BR(b\rightarrow sγ)$. One of the models studied provides an excellent fit to the low energy data with $χ^2\sim 1$ for 3 degrees of freedom, in a large region of the experimentally allowed SUSY parameter space. We also discuss the consequences of our work for a general MSSM analysis at the $Z$ scale.

hep-ph↗