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6.0

Jun 30, 2018
06/18

by
A. V. Bednyakov

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The results for the three-loop renormalization group equations for all fundamental parameters of the SM Lagrangian are presented. Special attention is paid to the Flavor sector of the SM, which parameterized by general complex non-diagonal Yukawa couplings. Some details of calculation techniques are given. In addition, ambiguities in the beta-functions for the matrix couplings are discussed.

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1411.1163

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9.0

Jun 30, 2018
06/18

by
A. V. Bednyakov

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The effective renormalizable theory describing electromagnetic and strong interactions of quarks of five light flavors ($n_f = 5$ QCD$\times$QED) is considered as a low-energy limit of the full Standard Model. Two-loop relation between the running strong coupling constants $\alpha_s$ defined in either theories is found by simultaneous decoupling of electroweak gauge and Higgs bosons in addition to the top quark. The relation potentially allows one to confront "low-energy determination of...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1410.7603

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81

Sep 18, 2013
09/13

by
A. V. Bednyakov

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The running mass of the b-quark defined in DRbar-scheme is one of the important parameters of SUSY QCD. To find its value it should be related to some known experimental input. In this paper the b-quark running mass defined in nonsupersymmetric QCD is chosen for determination of corresponding parameter in SUSY QCD. The relation between these two quantities is found by considering five-flavor QCD as an effective theory obtained from its supersymmetric extension. A numerical analysis of the...

Source: http://arxiv.org/abs/0707.0650v2

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65

Sep 19, 2013
09/13

by
A. V. Bednyakov

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Two-loop threshold corrections for both the strong coupling constant and Yukawa couplings of heavy SM fermions are considered in the context of Minimal Supersymmetric Standard Model (MSSM). With the help of the well-known SOFTSUSY code the dependence of the corrections on universal MSSM parameters is analyzed. For a consistent study of the influence of the corrections on SUSY mass spectrum three-loop renormalization group equations are implemented. A particular scenario (SPS4) is considered and...

Source: http://arxiv.org/abs/1009.5455v2

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116

Sep 17, 2013
09/13

by
A. V. Bednyakov

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Masses of heavy Standard Model fermions (top-quark, bottom-quark, and tau-lepton) play an important role in the analysis of theories beyond the SM. They serve as low-energy input and reduce the parameter space of such theories. In this paper Minimal supersymmetric extension of the SM is considered and two-loop relations between known SM values of fermion masses and running parameters of the MSSM are studied within the effective theory approach. Both b-quark and tau-lepton have the same quantum...

Source: http://arxiv.org/abs/0912.4652v1

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5.0

Jun 29, 2018
06/18

by
A. V. Bednyakov

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The talk is devoted to the problem of stability of the Standard Model vacuum. The effective potential for the Higgs field, which can potentialy exhibit additional, deeper minimum, is considered as a convenient tool for addressing the problem. Different methods and approximations used to calculate the potential are considered. Special attention is paid to the renomalization-group approach that allows one to carry out three-loop analysis of the problem. By means of an explicit gauge-independent...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1609.02503

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Jun 29, 2018
06/18

by
A. V. Bednyakov; A. F. Pikelner

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In the talk the leading four-loop contribution to the beta-function of the strong coupling in the SM is discussed. Some details of calculation techniques are provided. Special attention is paid to the ambiguity due to utilized $\gamma_5$ treatment and a particular prescription with anticommuting $\gamma_5$ is advocated. As a by-product of our computation the four-loop beta-function in QCD with "gluino" is also obtained.

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1609.02597

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20

Jun 28, 2018
06/18

by
A. V. Bednyakov; A. F. Pikelner

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In this letter we present our results for the four-loop beta-function of the strong coupling in the Standard Model of fundamental interactions. We take top-Yukawa and self-Higgs interactions into account, but neglect electroweak gauge couplings.

Topics: High Energy Physics - Phenomenology, High Energy Physics - Theory

Source: http://arxiv.org/abs/1508.02680

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139

Sep 23, 2013
09/13

by
A. V. Bednyakov; A. F. Pikelner; V. N. Velizhanin

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We present the results for three-loop beta-functions for Yukawa couplings of heavy Standard Model fermions calculated within the unbroken phase of the model. The calculation is carried out with the help of the MINCER program in a general linear gauge, and the final result is independent of the gauge-fixing parameters. In order to calculate three-point functions, we made use of infrared rearrangement (IRR) trick. Due to the chiral structure of the SM a careful treatment of loops with fermions is...

Source: http://arxiv.org/abs/1212.6829v3

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5.0

Jun 30, 2018
06/18

by
A. V. Bednyakov; A. F. Pikelner; V. N. Velizhanin

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We present the extension of our previous results for three-loop Yukawa coupling beta-functions to the case of complex Yukawa matrices describing the flavour structure of the SM. The calculation is carried out in the context of unbroken phase of the SM with the help of the MINCER program in a general linear gauge and cross-checked by means of MATAD/BAMBA codes. In addition, ambiguities in Yukawa matrix beta-functions are studied.

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1406.7171

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41

Sep 22, 2013
09/13

by
A. V. Bednyakov; A. F. Pikelner; V. N. Velizhanin

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We present the results for three-loop gauge field anomalous dimensions in the SM calculated in the background field gauge within the unbroken phase of the model. The results are valid for the general background field gauge parameterized by three independent parameters. Both quantum and background fields are considered. The former are used to find three-loop anomalous dimensions for the gauge-fixing parameters, and the latter allow one to obtain the three-loop SM gauge beta-functions....

Source: http://arxiv.org/abs/1210.6873v4

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51

Sep 21, 2013
09/13

by
A. V. Bednyakov; D. I. Kazakov; S. H. Tanyildizi

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We study the cross-section of heavy Higgs production at the LHC within the framework of the Constrained MSSM. It is not only enhanced by tan^2 beta but sometimes is also enhanced by the squark contribution. First, we consider the universal scenario within mSUGRA and find out that to get the desired enhancement one needs large negative values of A_0, which seems to be incompatible with the b->s gamma decay rate. To improve the situation, we release the unification requirement in the Higgs...

Source: http://arxiv.org/abs/1106.4385v4

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47

Sep 19, 2013
09/13

by
V. A. Bednyakov; N. D. Giokaris; A. V. Bednyakov

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The mass-generation mechanism is the most urgent problem of the modern particle physics. The discovery and study of the Higgs boson with the Large Hadron Collider at CERN are the highest priority steps to solve the problem. In this paper, the Standard Model Higgs mechanism of the elementary particle mass generation is reviewed with pedagogical details. The discussion of the Higgs quadric self-coupling \lambda parameter and the bounds to the Higgs boson mass are presented. In particular, the...

Source: http://arxiv.org/abs/hep-ph/0703280v1

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148

Sep 23, 2013
09/13

by
A. V. Bednyakov; A. F. Pikelner; V. N. Velizhanin

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We present the results for three-loop beta-function for the Higgs self-coupling calculated within the unbroken phase of the Standard Model. We also provide the expression for three-loop beta-function of the Higgs mass parameter, which is obtained as a by-product of our main calculation. Our results coincide with that of recent paper arXiv:1303.2890. In addition, the expression for the Higgs field anomalous dimension is given.

Source: http://arxiv.org/abs/1303.4364v2

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Jun 28, 2018
06/18

by
A. V. Bednyakov; B. A. Kniehl; A. F. Pikelner; O. L. Veretin

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We perform a manifestly gauge-independent analysis of the vacuum stability in the Standard Model (SM) including two-loop matching, three-loop renormalization group evolution, and pure QCD corrections through four loops. All these ingredients are exact, except that light-fermion masses are neglected. We in turn apply the criterion of nullifying the $\overline{\mathrm{MS}}$ Higgs self-coupling and its beta function and a recently proposed consistent method for determining the true minimum of the...

Topics: High Energy Physics - Phenomenology, High Energy Physics - Theory, General Relativity and Quantum...

Source: http://arxiv.org/abs/1507.08833

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26

Jun 29, 2018
06/18

by
A. V. Bednyakov; B. A. Kniehl; A. F. Pikelner; O. L. Veretin

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We consider electroweak corrections to the relation between the running $\overline{\mathrm{MS}}$ mass $m_b$ of the $b$ quark in the five-flavor QCD$\times$QED effective theory and its counterpart in the Standard Model (SM). As a bridge between the two parameters, we use the pole mass $M_b$ of the $b$ quark, which can be calculated in both models. The running mass is not a fundamental parameter of the SM Lagrangian, but the product of the running Yukawa coupling $y_b$ and the Higgs vacuum...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1612.00660