Reconciling EFT and hybrid calculations of the light MSSM Higgs-boson mass

Various methods are used in the literature for predicting the lightest CP-even Higgs boson mass in the Minimal Supersymmetric Standard Model (MSSM). Fixed-order diagrammatic calculations capture all effects at a given order and yield accurate results for scales of supersymmetric (SUSY) particles that are not separated too much from the weak scale. Effective field theory calculations allow a resummation of large logarithmic contributions up to all orders and therefore yield accurate results for a high SUSY scale. A hybrid approach, where both methods have been combined, is implemented in the computer code FeynHiggs. So far, however, at large scales sizeable differences have been observed between FeynHiggs and other pure EFT codes. In this work, the various approaches are analytically compared with each other in a simple scenario in which all SUSY mass scales are chosen to be equal to each other. Three main sources are identified that account for the major part of the observed differences. Firstly, it is shown that the scheme conversion of the input parameters that is commonly used for the comparison of fixed-order results is not adequate for the comparison of results containing a series of higher-order logarithms. Secondly, the treatment of higher-order terms arising from the determination of the Higgs propagator pole is addressed. Thirdly, the effect of different parametrizations in particular of the top Yukawa coupling in the non-logarithmic terms is investigated. Taking into account all of these effects, in the considered simple scenario very good agreement is found for scales above 1 TeV between the results obtained using the EFT approach and the hybrid approach of FeynHiggs.Comment: 31 pages, 5 figures, matches version published in EPJ

MSSM Higgs-boson mass predictions and two-loop non-supersymmetric counterterms

The evaluation of Yukawa-enhanced two-loop contributions to the MSSM Higgs-boson mass is considered. We prove the common assumption that regularization by dimensional reduction preserves supersymmetry at the required level. Thus generating counterterms by multiplicative renormalization is correct. Technically, we identify a suitable Slavnov-Taylor identity, use a recently developed method to evaluate it at the two-loop level, and show that it is valid in dimensional reduction.Comment: 14 pages, 2 figure

Precise Calculations for the Neutral Higgs-Boson Masses in the MSSM

We review the comparison of the results for the neutral CP-even Higgs-boson masses recently obtained within the Feynman-diagrammatic approach with the previous results based on the renormalization group approach. We show that the results differ by new genuine two-loop contributions present in the Feynman-diagrammatic calculation. The numerical effect of these terms on the result for m_h is briefly discussed

Calculation of fermionic two-loop contributions to muon decay

The computation of the correction \Delta r in the W-Z mass correlation, derived from muon decay, is described at the two-loop level in the Standard Model. Technical aspects which become relevant at this level are studied, e.g. gauge-parameter independent mass renormalization, ghost-sector renormalization and the treatment of \gamma_5. Exact results for \Delta r and the W mass prediction including O(\alpha^2) corrections with fermion loops are presented and compared with previous results of a next-to-leading order expansion in the top-quark mass

Pair Production of Two-Higgs-Doublet_Model Light Higgs Bosons in γγ\gamma \gamma Collisions

We study the production of a pair of light, neutral, CP-even Higgs bosons in photon--photon collisions within the general Two Higgs Doublet Model (THDM). This is a process for which the lowest order contribution in both, the Standard Model and the THDM, appears at one loop. We find that the cross section for this process can be much larger in the THDM than in the Standard Model and the number of events expected at the Photon Collider will allow a determination of some of the parameters in the scalar potential.Comment: 10 pages, 4 figure

Pop-up cavities

Метою роботи є дослідження маловивченого на теперішній час процесу переміщення збережених у приповерхневому вуглепородному масиві Донбасу пустот від місця їхнього первинного розташування до земної поверхні.The object of this paper is research into the understudied for now process of cavities, preserved in the sub-surface coal-bearing strata in the Donets Basin, moving from the places of their original location towards the surface.Целью работы является исследование малоизученного в настоящее время процесса перемещения сохранившихся в приповерхностном углепородном массиве Донбасса пустот от мест их первоначального расположения к земной поверхности. Методика исследования. Проанализированы фактические случаи так называемого всплывания пустот в угледобывающей практике. Выполнен абстрактный расчёт поэтапного всплывания условно сохранившейся выработки (пустоты) в породном массиве различной прочности