arXiv subjects

J. Rosiek

Publications and source records attributed to J. Rosiek.

At least 19 recordsLinked to original sources

arXiv2023

SmeftFR v3 -- Feynman rules generator for the Standard Model Effective Field Theory

We present version 3 of SmeftFR, a Mathematica package designed to generate the Feynman rules for the Standard Model Effective Field Theory (SMEFT) including the complete set of gauge invariant operators up to dimension-6 and the complete set of bosonic operators of dimension-8. Feynman rules are generated with the use of FeynRules package, directly in the physical (mass eigenstates) basis for all fields. The complete set of interaction vertices can be derived, including all or any chosen subset of SMEFT operators. As an option, the user can also choose preferred gauge fixing, generating Feynman rules in unitary or $R_ξ$-gauges. The novel feature in version-3 of SmeftFR is its ability to calculate SMEFT interactions consistently up to dimension-8 in EFT expansion (including quadratic dimension-6 terms) and express the vertices directly in terms of user-defined set of input-parameters. The derived Lagrangian in the mass basis can be exported in various formats supported by FeynRules, such as UFO, FeynArts etc. Initialisation of numerical values of Wilson coefficients of higher dimension operators is interfaced to WCxf format. The package also includes a dedicated Latex generator allowing to print the result in clear human-readable form. The SmeftFR v3 is publicly available at www.fuw.edu.pl/smeft.

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arXiv2019

Feynman Rules for the Standard Model Effective Field Theory in $R_ξ$-gauges

We assume that New Physics effects are parametrized within the Standard Model Effective Field Theory (SMEFT) written in a complete basis of gauge invariant operators up to dimension 6, commonly referred to as "Warsaw basis". We discuss all steps necessary to obtain a consistent transition to the spontaneously broken theory and several other important aspects, including the BRST-invariance of the SMEFT action for linear $R_ξ$-gauges. The final theory is expressed in a basis characterized by SM-like propagators for all physical and unphysical fields. The effect of the non-renormalizable operators appears explicitly in triple or higher multiplicity vertices. In this mass basis we derive the complete set of Feynman rules, without resorting to any simplifying assumptions such as baryon-, lepton-number or CP conservation. As it turns out, for most SMEFT vertices the expressions are reasonably short, with a noticeable exception of those involving 4, 5 and 6 gluons. We have also supplemented our set of Feynman rules, given in an appendix here, with a publicly available Mathematica code working with the FeynRules package and producing output which can be integrated with other symbolic algebra or numerical codes for automatic SMEFT amplitude calculations.

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arXiv2019

SmeftFR -- Feynman rules generator for the Standard Model Effective Field Theory

We present SmeftFR, a Mathematica package designed to generate the Feynman rules for the Standard Model Effective Field Theory (SMEFT) including the complete set of gauge invariant operators up to dimension~6. Feynman rules are generated with the use of FeynRules package, directly in the physical (mass eigenstates) basis for all fields. The complete set of interaction vertices can be derived including all or any chosen subset of SMEFT operators. As an option, the user can also choose preferred gauge fixing, generating Feynman rules in unitary or $R_ξ$-gauges (the latter include generation of ghost vertices). Further options allow to treat neutrino fields as massless Weyl or massive Majorana fermions. The derived Lagrangian in the mass basis can be exported in various formats supported by FeynRules, such as UFO, FeynArts, etc. Initialisation of numerical values of $d=6$ Wilson coefficients used by SmeftFR is interfaced to WCxf format. The package also includes dedicated Latex generator allowing to print the result in clear human-readable form. SmeftFR can be downloaded from www.fuw.edu.pl/smeft.

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arXiv2018

Effective Field Theories in R_xi gauges

In effective quantum field theories, higher dimensional operators can affect the canonical normalization of kinetic terms at tree level. These contributions for scalars and gauge bosons should be carefully included in the gauge fixing procedure, in order to end up with a convenient set of Feynman rules. We develop such a setup for the linear R_xi-gauges. It involves a suitable reduction of the operator basis, a generalized gauge fixing term, and a corresponding ghost sector. Our approach extends previous results for the dimension-six Standard Model Effective Field Theory to a generic class of effective theories with operators of arbitrary dimension.

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arXiv2018

The decay $h\to γγ$ in the Standard-Model Effective Field Theory

Assuming that new physics effects are parametrized by the Standard-Model Effective Field Theory (SMEFT) written in a complete basis of up to dimension-6 operators, we calculate the CP-conserving one-loop amplitude for the decay $h\to γγ$ in general $R_ξ$-gauges. We employ a simple renormalisation scheme that is hybrid between on-shell SM-like renormalised parameters and running $\overline{\mathrm{MS}}$ Wilson coefficients. The resulting amplitude is then finite, renormalisation scale invariant, independent of the gauge choice ($ξ$) and respects SM Ward identities. Remarkably, the $S$-matrix amplitude calculation resembles very closely the one usually known from renormalisable theories and can be automatised to a high degree. We use this gauge invariant amplitude and recent LHC data to check upon sensitivity to various Wilson coefficients entering from a more complete theory at the matching energy scale. We present a closed expression for the ratio $\mathcal{R}_{h\to γγ}$, of the Beyond the SM versus the SM contributions as appeared in LHC $h\to γγ$ searches. The most important contributions arise at tree level from the operators $Q_{φB}, Q_{φW}, Q_{φWB}$, and at one-loop level from the dipole operators $Q_{uB},Q_{uW}$. Our calculation shows also that, for operators that appear at tree level in SMEFT, one-loop corrections can modify their contributions by less than 10%. Wilson coefficients corresponding to these five operators are bounded from current LHC $h\to γγ$ data -- in some cases an order of magnitude stronger than from other searches. Finally, we correct results that appeared previously in the literature.

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arXiv2017

Dimension-Six Terms in the Standard Model Lagrangian

When the Standard Model is considered as an effective low-energy theory, higher dimensional interaction terms appear in the Lagrangian. Dimension-six terms have been enumerated in the classical article by Buchmueller and Wyler [3]. Although redundance of some of those operators has been already noted in the literature, no updated complete list has been published to date. Here we perform their classification once again from the outset. Assuming baryon number conservation, we find 15 + 19 + 25 = 59 independent operators (barring flavour structure and Hermitian conjugations), as compared to 16 + 35 + 29 = 80 in Ref.[3]. The three summed numbers refer to operators containing 0, 2 and 4 fermion fields. If the assumption of baryon number conservation is relaxed, 4 new operators arise in the four-fermion sector.

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arXiv2015

Mass Insertions vs. Mass Eigenstates calculations in Flavour Physics

We present and prove a theorem of matrix analysis, the Flavour Expansion Theorem (or FET), according to which, an analytic function of a Hermitian matrix can be expanded polynomially in terms of its off-diagonal elements with coefficients being the divided differences of the analytic function and arguments the diagonal elements of the Hermitian matrix. The theorem is applicable in case of flavour changing amplitudes. At one-loop level this procedure is particularly natural due to the observation that every loop function in the Passarino-Veltman basis can be recursively expressed in terms of divided differences. FET helps to algebraically translate an amplitude written in mass eigenbasis into flavour mass insertions, without performing diagrammatic calculations in flavour basis. As a non-trivial application of FET up to a third order, we demonstrate its use in calculating strong bounds on the real parts of flavour changing mass insertions in the up- squark sector of the MSSM from neutron Electric Dipole Moment (nEDM) measurements, assuming that CP-violation arises only from the CKM matrix.

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arXiv2014

Rare Top-quark Decays to Higgs boson in MSSM

In full one-loop generality and in next-to-leading order in QCD, we study rare top to Higgs boson flavour changing decay processes $t\to q h$ with $q=u,c$ quarks, in the general MSSM with R-parity conservation. Our primary goal is to search for enhanced effects on $Br(t\to q h)$ that could be visible at current and high luminosity LHC running. To this end, we perform an analytical expansion of the amplitude in terms of flavour changing squark mass insertions that treats both cases of hierarchical and degenerate squark masses in a unified way. We identify two enhanced effects allowed by various constraints: one from holomorphic trilinear soft SUSY breaking terms and/or right handed up squark mass insertions and another from non-holomorphic trilinear soft SUSY breaking terms and light Higgs boson masses. Interestingly, even with $\mathcal{O}(1)$ flavour violating effects in the, presently unconstrained, up-squark sector, SUSY effects on $Br(t\to q h)$ come out to be unobservable at LHC mainly due to leading order cancellations between penguin and self energy diagrams and the constraints from charge- and colour-breaking minima (CCB) of the MSSM vacuum. An exception to this conclusion may be effects arising from non-holomorphic soft SUSY breaking terms in the region where the CP-odd Higgs mass is smaller than the top-quark mass but this scenario is disfavoured by recent LHC searches. Our calculations for $t\to q h$ decay are made available in SUSY_FLAVOR numerical library.

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arXiv2014

SUSY_FLAVOR v2.5: a computational tool for FCNC and CP-violating processes in the MSSM

We present SUSY_FLAVOR version 2.5 - a Fortran 77 program that calculates low-energy flavor observables in the general $R$-parity conserving MSSM. For a set of MSSM parameters as input, the code gives predictions for: 1. Electric dipole moments of the leptons and the neutron. 2. Anomalous magnetic moments (i.e. $g-2$) of the leptons. 3. Radiative lepton decays ($μ\to eγ$ and $τ\to μγ, eγ$). 4. Rare Kaon decays ($K^0_L\to π^0\barνν$ and $K^+\to π^+ \barνν$). 5. Leptonic $B$ decays ($B_{s,d}\to l^+ l^-$, $B\to τν$, $B\to D τν$ and $B\to D^\star τν$). 6. Radiative $B$ decays ($B\to\bar X_s γ$). 7. Rare decays of top quark to Higgs boson ($t\to ch,uh$). 8. $ΔF=2$ processes ($\bar K^0-K^0$, $\bar D-D$, $\bar B_d-B_d$ and $\bar B_s-B_s$ mixing). SUSY_FLAVOR performs the resummation of all chirally enhanced corrections, i.e. takes into account the effects enhanced by $\tanβ$ and/or large trilinear soft mixing terms to all orders in perturbation theory. All calculations are done using exact diagonalization of the sfermion mass matrices. Comparing to previous versions, in SUSY_FLAVOR v2.5 parameter initialization in SLHA2 format has been significantly generalized and simplified, so that program accepts without modifications most of the output files produced by other codes calculating MSSM spectra and processes. In addition, the routine calculating branching ratios for rare decays of top quark to Higgs boson has been included. The program can be obtained from www.fuw.edu.pl/susy_flavor.

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arXiv2012

The W_L W_L scattering at the LHC: improving the selection criteria

We present a systematic study of the different mechanisms leading to WW pair production at the LHC, both in the same-sign and opposite-sign channels, and we emphasize that the former offers much better potential for investigating non-resonant W_L W_L scattering. We propose a new kinematic variable to isolate the W_L W_L scattering component in same-sign WW production at the LHC. Focusing on purely leptonic W decay channels, we show that it considerably improves the LHC capabilities to shed light on the electroweak symmetry breaking mechanism after collecting 100 fb^{-1} of data at sqrt{s} = 14 TeV. The new variable is less effective in the opposite-sign WW channel due to different background composition.

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arXiv2005

On the Neutral Scalar Sector of the General R-parity Violating MSSM

Starting out from the most general, gauge invariant and renormalizable scalar potential of the R-parity violating MSSM and performing a calculable rotation to the scalar fields we arrive at a basis where the sneutrino VEVs are zero. The advantage of our rotation is that, in addition, we obtain diagonal soft supersymmetry breaking sneutrino masses and all potential parameters and VEVs real, proving that the MSSM scalar potential does not exhibit spontaneous or explicit CP-violation at tree level. The model has five CP-even and four CP-odd physical neutral scalars, with at least one CP-even scalar lighter than M_Z. We parametrise the neutral scalar sector in a way that resembles the parametrisation of the R-parity conserving MSSM, analyze its mass spectrum, the coupling to the gauge sector and the stability of the potential.

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arXiv2003

$ΔM_{d,s}$, $B^0_{d,s}\toμ^+μ^-$ and $B\to X_sγ$ in Supersymmetry at Large $\tanβ$

We present an effective Lagrangian formalism for the calculation of flavour changing neutral and charged scalar currents in weak decays including $SU(2)\times U(1)$ symmetry breaking effects and the effects of the electroweak couplings $g_1$ and $g_2$. We apply this formalism to the MSSM with large $\tanβ$ with the CKM matrix as the only source of flavour violation, heavy supersymmetric particles and light Higgs bosons. We give analytic formulae for the neutral and charged Higgs boson couplings to quarks including large $\tanβ$ resummed corrections in the $SU(2) \times U(1)$ limit and demonstrate that these formulae can only be used for a semi-quantitative analysis. In particular they overestimate the effects of large $\tanβ$ resummed corrections. We give also improved analytic formulae that reproduce the numerical results of the full approach within $5-10%$. We present for the first time the predictions for the branching ratios $B^0_{s,d}\to μ^+μ^-$ and the $B^0_{d,s}-\bar B^0_{d,s}$ mass differences $ΔM_{d,s}$ that include simultaneously the resummed large $\tanβ$ corrections, $SU(2)\times U(1)$ breaking effects and the effects of the electroweak couplings. We perform an anatomy of the correlation between the increase of the rates of the decays $B^0_{s,d}\toμ^+μ^-$ and the suppression of $ΔM_s$, that for large $\tanβ$ are caused by the enhanced flavour changing neutral Higgs couplings to down quarks. We take into account the constraint from $B\to X_s γ$ clarifying some points in the calculation of the large $\tanβ$ enhanced corrections to this decay.

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arXiv2002

Correlation between Delta M_s and B^0_{s,d} --> mu^+ mu^- in Supersymmetry at Large tan beta

Considering the MSSM with the CKM matrix as the only source of flavour violation and heavy supersymmetric particles at large $\tanβ$, we analyze the correlation between {\it the increase} of the rates of the decays $B^0_{s,d}\to μ^+μ^-$ and {\it the suppression} of $ΔM_s$, that are caused by the enhanced flavour changing neutral Higgs couplings to down-type quarks. We give analytic formulae for the neutral and charged Higgs couplings to quarks including large $\tanβ$ resummed corrections in the $SU(2)\times U(1)$ limit and comment briefly on the accuracy of this approximation. For $0.8\le (ΔM_s)^{\rm exp}/(ΔM_s)^{\rm SM}\le 0.95$ we find $6\cdot 10^{-7}\ge BR(B^0_s\ra μ^+μ^-)^{\rm max} \ge 4\cdot 10^{-8}$ and $1.4\cdot 10^{-8}\ge BR(B^0_d\ra μ^+μ^-)^{\rm max}\ge 1\cdot 10^{-9}$. For $(ΔM_s)^{\rm exp} \ge (ΔM_s)^{\rm SM}$ substantial enhancements of $B^0_{s,d}\raμ^+μ^-$ relative to the expectations based on the Standard Model are excluded. With $(ΔM_s)^{\rm exp}>15.0/$ps a conservative analysis of $(ΔM_s)^{\rm SM}$ gives $BR(B^0_s\ra μ^+μ^-)\simlt1.2\cdot10^{-6}$ and $BR(B^0_d\ra μ^+μ^-)\simlt3\cdot10^{-8}$. However, we point out that in the less likely scenario in which the squark mixing is so large that the neutral Higgs contributions dominate $ΔM_s$, the rates for $B^0_{s,d}\to μ^+μ^-$ increase with increasing $ΔM_s$ and the bounds in question are weaker. Violation of all these correlations and bounds would indicate new sources of flavour violation.

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arXiv2002

Supersymmetry (at large tan beta) and flavour physics

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.

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arXiv2001

Neutral MSSM Higgs-boson production at e+e- colliders in the Feynman-diagrammatic approach

We calculate the cross sections for the neutral Higgs-boson production at e+e- colliders in the Minimal Supersymmetric Standard Model (MSSM) using the Feynman-diagrammatic approach and the on-shell renormalization scheme. We incorporate the Higgs-boson propagator corrections, evaluated up to two-loop order, into the prediction of the cross sections for the Higgs-boson production mechanism e+e- -> hZ, hA. The propagator corrections consist of the full one-loop contribution, including the effects of non-vanishing external momentum, and at the two-loop level of the dominant corrections of O(alpha alpha_s) and further sub-dominant contributions. The results are supplemented with the complete set of one-loop vertex and box corrections. The effects of the two-loop propagator corrections are investigated in detail. We briefly discuss also the effect of the box contributions for high $\sqrt{s}$. We compare our results with the case where only the corrections to the effective mixing angle, evaluated within the renormalization-group-improved one-loop Effective Potential approach, are taken into account. We find agreement better than 10% for LEP2 energies and deviations larger than 20% for $\sqrt{s}$ = 500 GeV.

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arXiv1999

Constraints on Phases of Supersymmetric Flavour Conserving Couplings

In the unconstrained MSSM, we reanalyze the constraints on the phases of supersymmetric flavour conserving couplings that follow from the electron and neutron electric dipole moments (EDM). We find that the constraints become weak if at least one exchanged superpartner mass is >O(1 TeV) or if we accept large cancellations among different contributions. However, such cancellations have no evident underlying symmetry principle. For light superpartners, models with small phases look like the easiest solution to the experimental EDM constraints. This conclusion becomes stronger the larger is the value of $\tanβ$. We discuss also the dependence of $ε_K$, $Δm_B$ and $b\to sγ$ decay on those phases.

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arXiv1996

Associated Production of Higgs Bosons and a Photon in High-Energy $e^+ e^-$ Collisions

We calculate the cross sections for the production of Higgs particles in association with a photon in $e^+ e^-$ collisions, $e^+ e^- \to γ+$Higgs, allowing for the longitudinal polarization of the initial electron and positron beams. We consider the associated production of both the Standard Model Higgs boson, and the neutral CP-even and CP-odd Higgs particles of its minimal supersymmetric extension. Complete and compact analytical expressions are given, and the size of the cross sections is illustrated for energies which will be reached at future $e^+ e^-$ colliders.

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arXiv1996

Higgs Physics at LEP2

In this report we review the prospects for Higgs physics at LEP2. The theoretical aspects and the phenomenology of Higgs particles are discussed within the Standard Model (SM) and the Minimal Supersymmetric Standard Model (MSSM). The experimental search techniques are described and the discovery limits for Higgs bosons in the LEP2 energy range are summarized. In addition, opportunities of detecting Higgs particles in non-minimal extensions of the SM and the MSSM are investigated.

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