Search

A holographic model of chiral symmetry breaking is used to study the dynamics plus the meson and baryon spectrum of the underlying strong dynamics in composite Higgs models. The model is inspired by top-down D-brane constructions. We introduce this model by applying it to $N_f=2$ QCD. We compute meson masses, decay constants and the nucleon mass. The spectrum is improved by including higher dimensional operators to reflect the UV physics of QCD. Moving to composite Higgs models, we impose perturbative running for the anomalous dimension of the quark condensate in a variety of theories with varying number of colors and flavours. We compare our results in detail to lattice simulations for the following theories: $SU(2)$ gauge theory with two Dirac fundamentals; $Sp(4)$ gauge theory with fundamental and sextet matter; and $SU(4)$ gauge theory with fundamental and sextet quarks. In each case, the holographic results are encouraging since they are close to lattice results for masses and decay constants. Moreover, our models allow us to compute additional observables not yet computed on the lattice, to relax the quenched approximation and move to the precise fermion content of more realistic composite Higgs models not possible on the lattice. We also provide a new holographic description of the top partners including their masses and structure functions. With the addition of higher dimension operators, we show the top Yukawa coupling can be made of order one, to generate the observed top mass. Finally, we predict the spectrum for the full set of models with top partners proposed by Ferretti and Karateev., 57 pages + 5 pages (appendices), 20 figures, 12 tables; v2: minor additions, added references

Tremendous phenomenological success of the Standard Model (SM) suggests that its flavor structure and gauge interactions may not be arbitrary but should have a fundamental first-principle explanation. In this work, we explore how the basic distinctive properties of the SM dynamically emerge from a unified New Physics framework tying together both flavour physics and Grand Unified Theory (GUT) concepts. This framework is suggested by a novel anomaly-free supersymmetric chiral $\mathrm{E}_6 \times \mathrm{SU}_F(2) \times \mathrm{U}_F(1)$ GUT containing the SM. Among the most appealing emergent properties of this theory is the Higgs-matter unification with a highly-constrained massless chiral sector featuring two universal Yukawa couplings close to the GUT scale. At the electroweak scale, the minimal SM-like effective field theory limit of this GUT represents a specific flavored three-Higgs doublet model consistent with the observed large hierarchies in the quark mass spectra and mixing already at tree level., 11 pages, 2 tables, 1 figure; discussion somewhat extended; published version

We investigate a scenario inspired by natural supersymmetry, where neutrino data is explained within a low-scale seesaw scenario. For this the Minimal Supersymmetric Standard Model is extended by adding light right-handed neutrinos and their superpartners, the R-sneutrinos. Moreover, we consider the lightest neutralinos to be Higgsino-like. We first update a previous analysis and assess to which extent does existing LHC data constrain the allowed slepton masses. Here we find scenarios where sleptons with masses as low as 175 GeV are consistent with existing data. However, we also show that the upcoming run will either discover or rule out sleptons with masses of 300 GeV, even for these challenging scenarios. We then take a scenario which is on the borderline of observability of the upcoming LHC run assuming a luminosity of 300 fb$^{-1}$. We demonstrate that a prospective international $e^+ e^-$ linear collider with a center of mass energy of 1 TeV will be able to discover sleptons in scenarios which are difficult for the LHC. Moreover, we also show that a measurement of the spectrum will be possible within 1-3 percent accuracy., Comment: 34 pages, 10 figures; v2: accepted for publication

Predictions for the Higgs masses are a distinctive feature of supersymmetric extensions of the Standard Model, where they play a crucial role in constraining the parameter space. The discovery of a Higgs boson and the remarkably precise measurement of its mass at the LHC have spurred new efforts aimed at improving the accuracy of the theoretical predictions for the Higgs masses in supersymmetric models. The “Precision SUSY Higgs Mass Calculation Initiative” (KUTS) was launched in 2014 to provide a forum for discussions between the different groups involved in these efforts. This report aims to present a comprehensive overview of the current status of Higgs-mass calculations in supersymmetric models, to document the many advances that were achieved in recent years and were discussed during the KUTS meetings, and to outline the prospects for future improvements in these calculations., Funded by SCOAP3., The work of S.H. has been supported in part by the MEINCOP (Spain) under contract FPA2016-78022-P and under contract PID2019-110058GB-C21, in part by the Spanish Agencia Estatal de Investigación (AEI), in part by the EU Fondo Europeo de Desarrollo Regional (FEDER) through the project FPA2016-78645-P, in part by the “Spanish Red Consolider MultiDark” FPA2017-90566-REDC, and in part by the AEI through the grant IFT Centro de Excelencia Severo Ochoa SEV-2016-0597.

We study natural supersymmetric scenarios with light right-handed neutrino superfields, and consider the possibility of having either a neutrino or a sneutrino as a dark matter candidate. For the former, we evaluate the possibility of having SUSY corrections on the ν4→ν γ decay rate, such that the NuStar bounds are relaxed. We find that corrections are too small. For sneutrino dark matter, we consider thermal and nonthermal production, taking into account freeze-out, freeze-in, and super-weakly interacting massive particles mechanisms. For the nonthermal case, we find that the νR can reproduce the observed relic density by adjusting the R-sneutrino mass and Yukawa couplings. For the thermal case, we find the need to extend the model in order to enhance sneutrino annihilations, which we exemplify in a model with an extended gauge symmetry. © 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/" Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

We demonstrate that in a recently proposed unified leptoquark model based on the gauge group SU(4)C×SU(2)L×U(1)R significant deviations from the Standard Model values of RK and RK* can be accommodated without any need of extra heavy fermions. Low energy data, in particular lepton-flavor-violating μ decays and KL→eμ, severely constrain the available parameter space. We show that in the allowed part of the parameter space (i) some of the lepton-flavor-violating tau decay branching ratios are predicted to be close to their current experimental limits. (ii) The underlying scalar leptoquarks can be probed at the LHC via their dominant decay modes into tau leptons and electrons and the third generation quarks. (iii) The constraints from meson oscillations imply that the masses of scalar gluons, another pair of colored multiplets around, have to be bigger than around 15 TeV, and thus, they can be probed only at a future 100 TeV collider. In both neutral and charged variants, these scalars decay predominantly into third generation quarks, with up to O(10%) branching ratios into family-mixed final states. Besides that, we comment on the phenomenology of the scalar gluons in the current scenarios in the case that the B-decay anomalies eventually disappear.

We provide gauge/gravity dual descriptions of the strong coupling sector of composite Higgs models using insights from non-conformal examples of the AdS/CFT correspondence. We calculate particle masses and decay constants for proposed Sp(4) and SU(4) gauge theories, where there is the best lattice data for comparison. Our results compare favorably to lattice studies and go beyond those due to a greater flexibility in choosing the fermion content. That content changes the running dynamics and its choice can lead to sizable changes in the bound state masses. We describe top partners by a dual fermionic field in the bulk. Including suitable higher dimension operators can ensure a top mass consistent with the standard model., Comment: 5 pages, 2 figures, 2 tables; v2 supplemental material added, references added

Constrained supersymmetric models like the CMSSM might look less attractive nowadays because of fine tuning arguments. They also might look less probable in terms of Bayesian statistics. The question how well the model under study describes the data, however, is answered by frequentist p-values. Thus, for the first time, we calculate a p-value for a supersymmetric model by performing dedicated global toy fits. We combine constraints from low-energy and astrophysical observables, Higgs boson mass and rate measurements as well as the non-observation of new physics in searches for supersymmetry at the LHC. Using the framework Fittino, we perform global fits of the CMSSM to the toy data and find that this model is excluded at more than 95% confidence level., 6 pages, 7 figures; To appear in the Proceedings of the 37th International Conference on High Energy Physics (ICHEP 2014), 2-9 July 2014, Valencia, Spain

The anomalies in the $B$-meson sector, in particular $R_{K^{(*)}}$ and $R_{D^{(*)}}$, are often interpreted as hints for physics beyond the Standard Model. To this end, leptoquarks or a heavy $Z'$ represent the most popular SM extensions which can explain the observations. However, adding these fields by hand is not very satisfactory as it does not address the big questions like a possible embedding into a unified gauge theory. On the other hand, light leptoquarks within a unified framework are challenging due to additional constraints such as lepton flavor violation. The existing accounts typically deal with this issue by providing estimates on the relevant couplings. In this letter we consider a complete model based on the $SU(4)_{\rm C}\otimes SU(2)_{\rm L}\otimes U(1)_{\rm R}$ gauge symmetry, a subgroup of $SO(10)$, featuring both scalar and vector leptoquarks. We demonstrate that this setup has, in principle, all the potential to accommodate $R_{K^{(*)}}$ and $R_{D^{(*)}}$ while respecting bounds from other sectors usually checked in this context. However, it turns out that $K_L \to e^{\pm} \mu^{\mp}$ severely constraints not only the vector but also the scalar leptoquarks and, consequently, also the room for any sizeable deviations of $R_{K^{(*)}}$ from 1. We briefly comment on the options for extending the model in order to conform this constraint. Moreover, we present a simple criterion for all-orders proton stability within this class of models., Comment: 9 pages, 7 figures, 2 tables

We investigate lepton flavour violation in a class of minimal left-right symmetric models where the left-right symmetry is broken by triplet scalars. In this context we present a method to consistently calculate the triplet-Yukawa couplings which takes into account the experimental data while simultaneously respecting the underlying symmetries. Analysing various scenarios, we then calculate the full set of tree-level and one-loop contributions to all radiative and three-body flavour-violating fully leptonic decays as well as $\mu-e$ conversion in nuclei. Our method illustrates how these processes depend on the underlying parameters of the theory. To that end we observe that, for many choices of the model parameters, there is a strong complementarity between the different observables. For instance, in a large part of the parameter space, lepton flavour violating $\tau$-decays have a large enough branching ratio to be measured in upcoming experiments. Our results further show that experiments coming online in the immediate future, like Mu3e and BELLE II, or longer-term, such as PRISM/PRIME, will probe significant portions of the currently allowed parameter space., Comment: 49 pages, 19 figures; references added, the discussion in appendix A has been extended, matches published version in JHEP

We present the possibility of calculating the quark flavor changing neutral current decays B s 0 → l l and B d 0 → l l for a large variety of supersymmetric models. For this purpose, the complete one-loop calculation has been implemented in a generic form in the Mathematica package SARAH . This information is used by SARAH to generate Fortran source code for SPheno for a numerical evaluation of these processes in a given model. We comment also on the possibility to use this setup for non-supersymmetric models. Program summary Program title: SARAH Catalogue identifier: AEIB_v2_1 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEIB_v2_1.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 467777 No. of bytes in distributed program, including test data, etc.: 3927691 Distribution format: tar.gz Programming language: Mathematica, Fortran. Computer: All computers which can run Mathematica and SPheno. Operating system: Linux, MacOS. Classification: 11.1, 11.6. Catalogue identifier of previous version: AEIB_v2_0 Journal reference of previous version: Comput. Phys. Comm. 184 (2013) 1792 Does the new version supercede the previous version?: Yes, the new version includes all known features of previous versions but provides also the new features mentioned below. Nature of problem: Models beyond the SM can have new contributions to the decays of neutral B-mesons. For a precise prediction of the corresponding branching ratios a full 1-loop calculation including all possible wave, penguin and box diagrams is necessary. This usually requires a big effort and public codes for these calculations so far only support a few selected models. Solution method: The implementation of a new model in SARAH is easy and straightforward. In addition, SARAH is already delivered with many different supersymmetric and a few non-supersymmetric models. As a first step, SARAH derives the analytical expressions for masses, interactions and renormalization group equations for the given model. Furthermore, SARAH checks for all possible tree- and 1-loop diagrams which can contribute to the B-meson decays into two leptons. This information is exported to Fortran source code which can afterwards be compiled with SPheno. This generates a fully functional spectrum generator: besides the mass spectrum, sparticle and Higgs decays the new SPheno modules also calculate precision observables like the B-meson decays based on the parameters chosen by the user. Reasons for new version: The possible decays of neutral B-mesons into two leptons are constraining models beyond the Standard Model. SARAH allows, in the new version, the production of SPheno source code to calculate those decays at full 1-loop for a large variety of models. Summary of revisions: Full 1-loop calculation of B s , d 0 → l l for any model which can be implemented in SARAH. Restrictions: SARAH can only calculate the renormalization group equations for a supersymmetric model. Hence, for a non-supersymmetric model it is not possible to calculate the running parameters which enter the calculation. These have to be provided by the user as input. In addition, the effects of chiral resummation as well as next-to-leading order QCD corrections known for the MSSM are not included. Unusual features: This is the first public tool which allows a full 1-loop calculation of B-meson decays in more complicated models than the minimal or next-to-minimal supersymmetric standard model. Any new contribution in a renormalizable model stemming from an extended matter content or gauge sector is taken into account. Running time: Measured CPU time for the evaluation of the MSSM using a Lenovo Thinkpad X220 with i7 processor (2.53 GHz). Calculating the complete Lagrangian: 9 s. Calculating all vertices: 51 s. Output of the UFO model files: 49 s.

We present an extensive study of the MSSM parameter space allowing for general generation mixing in the squark sector. Employing an MCMC algorithm, we establish the parameter ranges which are allowed with respect to various experimental and theoretical constraints. Based on this analysis, we propose benchmark scenarios for future studies. Moreover, we discuss aspects of signatures at the LHC., 4 pages, 3 figures. Contribution to the proceedings of the 38th International Conference of High Energy Physics (ICHEP), Chicago, Aug. 3-10, 2016

We consider a scenario inspired by natural supersymmetry, where neutrino data is explained within a low-scale seesaw scenario. We extend the Minimal Supersymmetric Standard Model by adding light right-handed neutrinos and their superpartners, the R-sneutrinos, and consider the lightest neutralinos to be higgsino-like. We consider the possibilities of having either an R-sneutrino or a higgsino as lightest supersymmetric particle. Assuming that squarks and gauginos are heavy, we systematically evaluate the bounds on slepton masses due to existing LHC data., Comment: 26 pages, 8 figures, 2 appendices; v2: Minor changes, version accepted for publication in EPJC

For a long time, the minimal supersymmetric standard model (MSSM) with light masses for the supersymmetric states was considered as the most natural extension of the Standard Model of particle physics. Consequently, a valid approximation was to match the MSSM to the precision measurement directly at the electroweak scale. This approach was also utilized by all dedicated spectrum generators for the MSSM. However, the higher the supersymmetric (SUSY) scale is, the bigger the uncertainties which are introduced by this matching. We point out important consequences of a two-scale matching, where the running parameters within the SM are calculated at $M_Z$ and evaluated up to the SUSY scale, where they are matched to the full model. We show the impact on gauge coupling unification as well as the SUSY mass spectrum. Also the Higgs mass prediction for large supersymmetric masses has been improved by performing the calculation within an effective SM. The approach presented here is now also available in the spectrum generator SPheno. Moreover, also SARAH was extended accordingly and gives the possibility to study these effects now in many different supersymmetric models., 24 pages, 13 figures; v2) A few clarifications added, matches published version

We present an extensive study of non-minimally flavour violating (NMFV) terms in the Lagrangian of the Minimal Supersymmetric Standard Model (MSSM). We impose a variety of theoretical and experimental constraints and perform a detailed scan of the parameter space by means of a Markov Chain Monte-Carlo (MCMC) setup. This represents the first study of several non-zero flavour-violating elements within the MSSM. We present the results of the MCMC scan with a special focus on the flavour-violating parameters. Based on these results, we define benchmark scenarios for future studies of NMFV effects at the LHC.

We present an on-shell renormalization scheme for the neutralino and chargino mass matrices for two R-parity violating models, namely bilinear R-parity violation and the munuSSM with one right-handed neutrino superfield. We discuss in both models how to obtain neutrino masses and mixing angles correctly as well as differences to the existing DRbar calculations. Both models predict correlations between neutrino mixing angles and ratios of R-parity violating decays such as neutralino_1 -> l W which can be tested for example at the LHC. We point out that there are cases where one has to include the complete NLO corrections for the decays neutralino_1 -> l W to predict reliably the correlations between neutrino- and collider-physics. Moreover, we discuss briefly the implementation of these decays in the public program CNNDecays., 30 pages, 20 figures; minor corrections, published in Nuclear Physics B

We generalize the two-loop renormalization group equations for the parameters of the softly broken SUSY gauge theories given in the literature to the most general case when the gauge group contains more than a single Abelian gauge factor. The complete method is illustrated at two-loop within a specific example and compared to some of the previously proposed partial treatments.

We study the effect of squark generation mixing on squark production and decays at the LHC in the Minimal Supersymmetric Standard Model (MSSM). We show that the effect can be very large despite the very strong constraints on quark flavour violation (QFV) from experimental data on B mesons. We find that the two lightest up-type squarks can have large branching ratios for the decays into and at the same time, leading to QFV signals ‘ + missing-ET + X′ with a significant rate. The observation of this remarkable signature would provide a powerful test of supersymmetric QFV at LHC. This could have a significant impact on the search for squarks and the determination of the underlying MSSM parameters.

A non-Abelian flavour symmetry in a minimal supersymmetric standard model can explain the flavour structures in the Yukawa couplings and simultaneously solve the SUSY flavour problem. Similarly the SUSY CP problem can be solved if CP is spontaneously broken in the flavour sector. In this work, we present an explicit example of these statements with a SU(3) flavour symmetry and spontaneous CP violation. In addition, we show that it is still possible to find some significant deviation from the SM expectations as far as FCNC and CP violation are concerned. We find that large contributions can be expected in lepton flavour violating decays, as � ! e and � ! � , electric dipole moments, de and dn and kaon CP

We investigate the constrained Minimal Supersymmetric Standard Model (cMSSM) in the light of constraining experimental and observational data from precision measurements, astrophysics, direct supersymmetry searches at the LHC and measurements of the properties of the Higgs boson, by means of a global fit using the program Fittino. As in previous studies, we find rather poor agreement of the best fit point with the global data. We also investigate the stability of the electro-weak vacuum in the preferred region of parameter space around the best fit point. We find that the vacuum is metastable, with a lifetime significantly longer than the age of the Universe. For the first time in a global fit of supersymmetry, we employ a consistent methodology to evaluate the goodness-of-fit of the cMSSM in a frequentist approach by deriving p-values from large sets of toy experiments. We analyse analytically and quantitatively the impact of the choice of the observable set on the p-value, and in particular its dilution when confronting the model with a large number of barely constraining measurements. Finally, for the preferred sets of observables, we obtain p-values for the cMSSM below 10%, i.e. we exclude the cMSSM as a model at the 90% confidence level., 22 pages, 16 figures, to be submitted to EPJ C

We perform the first analysis of Dark Matter scenarios in a constrained model with Dirac Gauginos. The model under investigation is the Constrained Minimal Dirac Gaugino Supersymmetric Standard model (CMDGSSM) where the Majorana mass terms of gauginos vanish. However, $R$-symmetry is broken in the Higgs sector by an explicit and/or effective $B_\mu$-term. This causes a mass splitting between Dirac states in the fermion sector and the neutralinos, which provide the dark matter candidate, become pseudo-Dirac states. We discuss two scenarios: the universal case with all scalar masses unified at the GUT scale, and the case with non-universal Higgs soft-terms. We identify different regions in the parameter space which fullfil all constraints from the dark matter abundance, the limits from SUSY and direct dark matter searches and the Higgs mass. Most of these points can be tested with the next generation of direct dark matter detection experiments., Comment: 28 pages, 11 figures; v2: minor changes, title modified; matches published version

We have explored Natural Supersymmetry (NSUSY) scenarios with low values of the $\mu$ parameter which are characterised by higgsino-like Dark Matter (DM) and compressed spectra for the lightest MSSM particles, $\chi^0_1$, $\chi^0_2$ and $\chi^\pm_1$. This scenario could be probed via monojet signatures, but as the signal-to-background ratio (S/B) is low we demonstrate that the 8 TeV LHC cannot obtain limits on the DM mass beyond those of LEP2. On the other hand, we have found, for the 13 TeV run of the LHC, that by optimising kinematical cuts we can bring the S/B ratio up to the 5(3)% level which would allow the exclusion of the DM mass up to 200(250) GeV respectively, significantly extending LEP2 limits. Moreover, we have found that LUX/XENON1T and LHC do play very complementary roles in exploring the parameter space of NSUSY, as the LHC has the capability to access regions where DM is quasi-degenerate with other higgsinos, which are challenging for direct detection experiments., Comment: 28 pages, 13 Figures, minor changes, version published in JHEP

We discuss the impact of additional two-body decays of the right-handed neutrino into a light charged Higgs state on the dilepton plus dijet cross sections from resonant $W'$ production. We consider in particular a supersymmetric left-right symmetric model which predicts such a light charged Higgs boson. We demonstrate that the $eejj$ excess as measured by CMS can be explained best if the $W'$ also has decay modes into Higgsino-like charginos and neutralinos with masses of a few hundred GeV. Provided that this excess is confirmed, the model predicts also one right-handed neutrino with a mass below 200 GeV as well as a doubly charged Higgs boson which should be discovered at the LHC in the near future., 8 pages, 4 figures; v2: minor changes, references added; matches published version

We present an analysis of supersymmetric left-right symmetric models with Higgs fields lying in the adjoint representation of $SU(2)_R$. These models feature a doubly-charged Higgs boson which gets its mass only at the loop level. We present, for the first time, a complete one-loop calculation of this mass and show that contributions that have been neglected so far can shift it by a few hundreds of GeV. We then combine this observation with LHC bounds deduced from extra charged gauge boson and doubly-charged Higgs boson searches. In particular, we point out that existing limits get substantially modified by the presence of singly-charged Higgs bosons that are also predicted in these models. In addition, we address constraints stemming from vacuum stability considerations and show how the considered class of models could be ruled out at the next LHC run in the absence of any signal., Comment: 25 pages, 11 figures; v2: extended analytical considerations on vacuum stability, added figure 10. Matches published version

Natural SUSY scenarios with a low value of the $\mu$ parameter, are characterised by a higgsino-like dark matter candidate, and a compressed spectrum for the lightest higgsinos. We explore the prospects for probing this scenario at the 13 TeV stage of the LHC via monojet searches, with various integrated luminosity options, and demonstrate how these results are affect by different assumptions on the achievable level of control on the experimental systematic uncertainties. The complementarity between collider and direct detection experiments (present and future) is also highlighted., Comment: Proceeding for the 18th International Conference From the Planck Scale to the Electroweak Scale (Ioannina, Greece, 25-29 May 2015)

The direct CP asymmetry in the untagged inclusive channel B ¯ → X s + d γ provides a strict test of the standard model. It has been shown beyond the partonic level that this asymmetry is negligibly small thanks to U-spin relations and to the unitarity of the CKM matrix. In the present paper we investigate this relation beyond the SM; in particular, we analyse to which extent deviations from this prediction are possible in supersymmetric scenarios. We analyse the minimal flavour violation scenario, including tan β -enhanced terms and using the complete two-loop renormalization group running. Our analysis fully takes into account also the EDM constraints on the supersymmetric phases. We also investigate possible correlations between the tagged and the untagged CP asymmetries and the indirect sensitivity of the latter to the B ¯ → X d γ CP asymmetry. Furthermore, we derive general model-independent formulae for the branching ratios and CP asymmetries for the inclusive B ¯ → X d γ and B ¯ → X s γ modes, and update the corresponding SM predictions. We obtain for a photon energy cut-off E 0 = 1.6 GeV : B [ B ¯ → X s γ ] = ( 3.61 −0.40 +0.24 | m c / m b ± 0.02 CKM ± 0.24 param . ± 0.14 scale ) × 10 −4 , A CP [ B ¯ → X s γ ] = ( 0.42 −0.08 +0.08 | m c / m b ± 0.03 CKM −0.08 +0.15 | scale ) % .

We summarize methods and expected accuracies in determining the basic low-energy SUSY parameters from experiments at future e$^+$e$^-$ linear colliders in the TeV energy range, combined with results from LHC. In a second step we demonstrate how, based on this set of parameters, the fundamental supersymmetric theory can be reconstructed at high scales near the grand unification or Planck scale. These analyses have been carried out for minimal supergravity [confronted with GMSB for comparison], and for a string effective theory., 8 pages, latex, 7 figures, expanded version of contributions to the proceedings of ICHEP.2002 (Amstersdam) and LCWS.2002 (Jeju Island)

In this erratum to “Electroweak corrections to neutralino and chargino decays into a W-boson in the (N)MSSM” we correct an error in the Bremsstrahlung integrals and adopt the renormalization of the electric charge. The adjustments do not change the statements given in the original publication.

We study the decays of the τ-sleptons ( τ 1,2 ) and τ-sneutrino ( ν τ ) in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters Aτ,μ and M1 (U(1) gaugino mass). We show that the effect of the CP phases of these parameters on the branching ratios of τ 1,2 and ν τ decays can be quite strong in a large region of the MSSM parameter space. This could have an important impact on the search for τ 1,2 and ν τ and the determination of the MSSM parameters at future colliders.

We investigate selectron pair production and decay in e-e- scattering and e+e- annihilation with polarized beams taking into account neutralino mixing as well as ISR and beamstrahlung corrections. One of the main advantages of having both modes at disposal is their complementarity concerning the threshold behaviour of selectron pair production. In e-e- the cross sections at threshold for seleectron_R selectron_R and selectron_L selectron_L rise proportional to the momentum of the selectron and in e+ e- that for selectron_R selectron_L. Measurements at threshold with polarized beams can be used to determine the selectron masses precisely. Moreover we discuss how polarized electron and positron beams can be used to establish directly the weak quantum numbers of the selectrons. We also use selectron pair production to determine the gaugino mass parameter M_1. This is of particular interest for scenarios with non-universal gaugino masses at a high scale resulting in |M_1| << |M_2| at the electroweak scale. Moreover, we consider also the case of a non-vanishing selectron mixing and demonstrate that it leads to a significant change in the phenomenology of selectrons., LaTex, 23 pages, 14 figures, v2, typos corrected, version to appear in Eur.Phys.J.C

We consider the three-body decay t 1 →b ν τ τ + and propose the asymmetry of the τ polarization perpendicular to the decay plane as a CP sensitive observable. We calculate this asymmetry in the Minimal Supersymmetric Standard Model with the parameters μ and A t complex. In the parameter domain where the decay t 1 →b ν τ τ + is important this asymmetry can go up to ±30%. We also estimate the event rates necessary to observe this asymmetry at 90% CL.

Taking the supersymmetric inverse seesaw mechanism as the explanation for neutrino oscillation data, we investigate charged lepton flavor violation in radiative and 3-body lepton decays as well as in neutrinoless $\mu-e$ conversion in muonic atoms. In contrast to former studies, we take into account all possible contributions: supersymmetric as well as non-supersymmetric. We take CMSSM-like boundary conditions for the soft supersymmetry breaking parameters. We find several regions where cancellations between various contributions exist, reducing the lepton flavor violating rates by an order of magnitude compared to the case where only the dominant contribution is taken into account. This is in particular important for the correct interpretation of existing data as well as for estimating the reach of near future experiments where the sensitivity will be improved by one to two orders of magnitude. Moreover, we demonstrate that ratios like BR($\tau\to 3 \mu$)/BR($\tau\to \mu e^+ e^-$) can be used to determine whether the supersymmetric contributions dominate over the $W^\pm$ and $H^\pm$ contributions or vice versa., Comment: 75 pages, 7 figures. v3: references and comments added. Matches published version

Supersymmetric models with bilinear $R$-parity violation (BRpV) provide a framework for neutrino masses and mixing angles to explain neutrino oscillation data. We consider $CP$ violation within the new physical phases in BRpV and discuss their effect on the generation of neutrino masses and the decays of the lightest supersymmetric particle (LSP), being a light neutralino with mass $\ensuremath{\sim}100\text{ }\text{ }\mathrm{GeV}$, at next-to-leading order. The decays affect the lepton and via sphaleron transitions the baryon asymmetry in the early universe. For a rather light LSP, asymmetries generated before the electroweak phase transition via e.g. the Affleck-Dine mechanism are reduced up to 2 orders of magnitude, but are still present. On the other hand, the decays of a light LSP themselves can account for the generation of a lepton and baryon asymmetry, the latter in accordance with the observation in our universe, since the smallness of the BRpV parameters allows for an out-of-equilibrium decay and sufficiently large $CP$ violation is possible consistent with experimental bounds from the nonobservation of electric dipole moments.

We present a new kit for the study of flavor observables in models beyond the standard model. The setup is based on the public codes SARAH and SPheno and allows for an easy implementation of new observables. The Wilson coefficients of the corresponding operators in the effective Lagrangian are computed by SPheno modules written by SARAH. New operators can also be added by the user in a modular way. For this purpose a handy Mathematica package called PreSARAH has been developed. This uses FeynArts and FormCalc to derive the generic form factors at tree- and 1-loop levels and to generate the necessary input files for SARAH. This framework has been used to implement BR($\ell_\alpha\to \ell_\beta \gamma$), BR($\ell_\alpha \to 3\, \ell_\beta$), CR($\mu-e,A$), BR($\tau \to P \, \ell$), BR($h\to \ell_\alpha \ell_\beta$), BR($Z\to \ell_\alpha \ell_\beta$), BR($B_{s,d}^0 \to \ell \bar{\ell}$), BR($\bar B \to X_s\gamma$), BR($\bar B \to X_s \ell \bar{\ell}$), BR($\bar B \to X_{d,s} \nu \bar \nu$), BR($K^+ \to \pi^+ \nu \bar \nu$), BR($K_L \to \pi^0 \nu \bar \nu$), $\Delta M_{B_s,B_d}$, $\Delta M_K$, $\varepsilon_K$, BR($B \to K \mu \bar{\mu}$), BR($B\to \ell \nu$), BR($D_s \to \ell \nu$) and BR($K \to \ell \nu$) in SARAH. Predictions for these observables can now be obtained in a wide range of SUSY and non-SUSY models. Finally, the user can use the same approach to easily compute additional observables., Comment: 68 pages; PreSARAH and FlavorKit (included in SARAH 4.2.0) can be downloaded at http://sarah.hepforge.org/FlavorKit.html; v2: minor extensions, matches published version; v3: unifying layout in the appendix

We examine the possibilities for constructing models with Dirac gaugino masses and unification of gauge couplings. We identify one promising model, and discuss to what extent it can have a "natural SUSY" spectrum. We then determine the low-energy constraints upon it, and propose a constrained set of boundary conditions at the unification scale. We describe the implementation of these boundary conditions in the spectrum-generator generator \SARAH and we perform a first exploration of the parameter space, specifically searching for points where the spectrum is relatively light. It is shown that the pattern of the masses of SUSY states is very different compared to any expectations from the constrained MSSM., 31 + 28 pages, 10 figures, 1 table

There have been some recent claims in the literature about large right-handed sneutrinos contributions to lepton flavor violating observables like $\mu \to 3e$ or $\mu - e$ conversion in nuclei in supersymmetric low-scale seesaw models. These large contributions originate from $Z$-penguin diagrams which show a much weaker dependence on the heavy masses than the photonic contributions. We have traced this to an error in the evaluation of the corresponding loop amplitudes which has propagated in the literature. We explicitly show that after correcting this mistake the $Z$-penguins show the expected decoupling behavior. Moreover, the reported dominance of the $Z$-penguin over the photonic contributions disappears as well., Comment: 7 pages, 2 figures; v2: minor changes, appendix added; matches published version in PRD

We discuss higher dimensional effective operators describing interactions between fermionic dark matter and Standard Model particles. They are typically suppressed compared to the leading order effective operators, which can explain why no conclusive direct dark matter detection has been made so far. The ultraviolet completions of the effective operators, which we systematically study, require new particles. These particles can potentially have masses at the TeV scale and can therefore be phenomenologically interesting for LHC physics. We demonstrate that the lowest order options require Higgs-portal interactions generated by dimension six operators. We list all possible tree-level completions with extra fermions and scalars, and we discuss the LHC phenomenology of a specific example with extra heavy fermion doublets., 27 pages, 11 figures, 3 tables

We discuss production and decays of stops, sbottoms, τ-sneutrinos, and staus in e+e− annihilation in the energy range √s = 0.5-1TeV. We present numerical predictions within the Minimal Supersymmetric Standard Model for cross sections and decay rates, including one-loop radiative corrections as well as initial state radiation. We also study the importance of beam polarization for the determination of the underlying SUSY parameters. Moreover, we make a comparison of the potential to study squarks and sleptons of the 3rd generation between Tevatron, LHC, and Linear Collider.

We calculate the supersymmetric ${\cal O}(\alpha_s)$ QCD corrections to stop and sbottom decays into vector bosons within the Minimal Supersymmetric Standard Model. We give analytic formulae and perform a numerical analysis of these decays. We find that SUSY-QCD corrections to the decay widths are typically -5% to -10% depending on the squark masses, squark mixing angles, and the gluino mass.

We re-evaluate the constraints on the parameter space of the minimal supersymmetric standard model from tunneling to charge- and/or color-breaking minima, taking into account thermal corrections. We pay particular attention to the region known as the Natural MSSM, where the masses of the scalar partners of the top quarks are within an order of magnitude or so of the electroweak scale. These constraints arise from the interaction between these scalar tops and the Higgs fields, which allows the possibility of parameter points having deep charge- and color-breaking true vacua. In addition to requiring that our electro-weak-symmetry-breaking, yet QCD- and electromagnetism-preserving vacuum has a sufficiently long lifetime at zero temperature, also demanding stability against thermal tunneling further restricts the allowed parameter space., Comment: 7 pages, 2 figures, software available from http://vevacious.hepforge.org/ - version 2 matches that accepted for publication in Phys. Lett. B

We study quark flavour violation (QFV) in the squark sector of the Minimal Supersymmetric Standard Model (MSSM). We assume mixing between the second and the third squark generations, i.e. sc_R-st_{L,R} mixing mixing. We focus on QFV effects in bosonic squark decays, in particular on the decay into the lightest Higgs boson h0, su_2 -> su_1 h0, where su_{1,2} are the lightest up-type squarks. We show that the branching ratio of this QFV decay can be quite large (up to 50 %) due to large QFV trilinear couplings, and large sc_R-st_{L, R} and st_L-st_R mixing, despite the strong constraints on QFV from B meson data. This can result in characteristic QFV final states with significant rates at LHC (14 TeV), such as pp -> gluino gluino X -> t + h0 + 3jets + Etmiss + X and pp -> gluino gluino X -> t t (or tbar tbar) + h0 + 2jets + Etmiss + X. The QFV bosonic squark decays can have an influence on the squark and gluino searches at LHC., Figure 3 replaced, Section 4 revised

We perform a study of the stability of R-parity-conserving vacua of a constrained version of the minimal supersymmetric model with a gauged U(1)_{B-L} which can conserve R-parity, using homotopy continuation to find all the extrema of the tree-level potential, for which we also calculated the one-loop corrections. While we find that a majority of the points in the parameter space preserve R-parity, we find that a significant portion of points which naively have phenomenologically acceptable vacua which conserve R-parity actually have deeper vacua which break R-parity through sneutrino VEVs. We investigate under what conditions the deeper R-parity-violating vacua appear. We find that while previous exploratory work was broadly correct in some of its qualitative conclusions, we disagree in detail.

We consider a supersymmetric model motivated by a SO(10) grand unified theory: the gauge sector near the supersymmetry scale consists of SU(3)_c x SU(2)_L x U(1)_R x U(1)_{B-L}. We embed this model in minimal gauge mediation and incorporate neutrino data via an inverse seesaw mechanism. Also in this restricted model, the additional D terms can rise the light Higgs mass in a sizable way. Therefore, it is much easier to obtain m_h \simeq 125 GeV without the need to push the supersymmetry spectrum to extremely large values as it happens in models with minimal supersymmetric standard model particle content only. We show that this model predicts a diphoton rate of the Higgs equal to or smaller than the standard model expectation. We discuss briefly the collider phenomenology with a particular focus on the next to lightest supersymmetric particle in which this model offers the sneutrino as an additional possiblity. Moreover, we point out that, also in this model variant, supersymmetry can be discovered in Z' decays even in scenarios in which the strongly interacting particles are too heavy to be produced at a sizable rate at the LHC with 14 TeV. In addition, we show that lepton flavor violating observables constrain the size of the neutrino Yukawa couplings for which, in particular, muon decays and \mu-e conversion in heavy atoms are of particular importance. Once these constraints are fulfilled the rates for \tau decays are predicted to be below the reach of near-future experiments.

Several extensions of the Standard Model of particle physics contain additional scalars implying a more complex scalar potential compared to that of the Standard Model. In general these potentials allow for charge and/or color breaking minima besides the desired one with correctly broken SU(2)_L times U(1)_Y . Even if one assumes that a metastable local minimum is realized, one has to ensure that its lifetime exceeds that of our universe. We introduce a new program called Vevacious which takes a generic expression for a one-loop effective potential energy function and finds all the tree-level extrema, which are then used as the starting points for gradient-based minimization of the one-loop effective potential. The tunneling time from a given input vacuum to the deepest minimum, if different from the input vacuum, can be calculated. The parameter points are given as files in the SLHA format (though is not restricted to supersymmetric models), and new model files can be easily generated automatically by the Mathematica package SARAH. This code uses HOM4PS2 to find all the minima of the tree-level potential, PyMinuit to follow gradients to the minima of the one-loop potential, and CosmoTransitions to calculate tunneling times., 44 pages, 1 figure, manual for publicly available software, v2 corresponds to version accepted for publication in EPJC [clearer explanation of scale dependence and region of validity, explicit mention that SLHA files should have blocks matching those expected by model files, updated references]

Models, where neutrino mass originates from physics at the TeV scale and which are potentially testable at the LHC, need additional suppression mechanisms to describe the smallness of neutrino masses. We consider models in which neutrino mass is generated from the d=7 operator $L L H_u H_u H_d H_u$ in the context of SUSY-GUTs containing an SU(5) subgroup, here the d=5 Weinberg operator can be forbidden by a discrete symmetry. That is, we identify the embeddings in GUT multiplets and their consequences for phenomenology and renormalization group evolution. We use a specific example to exemplify the challenges. In this case, additional heavy d-quarks are predicted, which are constrained by cosmology, in particular, by big bang nucleosynthesis and direct searches for heavy nuclei. We show that in the NMSSM extension of the model, the discrete symmetry needs to be broken, which can be the origin of deviations from tri-bimaximal mixings. Finally we demonstrate that our example is the only tree level decomposition which is consistent with perturbativity up to the GUT scale and neutrino mass generation by a leading d=7 contribution., 16 pages, 1 figure, 4 tables

The existence of multiple non-equivalent minima of the scalar potential in SUSY models both raises technical challenges and introduces interesting physics. The technical challenges are now that one has to find several minima and evaluate which is the deepest, as well as calculate the tunneling time from a false vacuum to the true vacuum. We present here studies on the vacuum stability and color/charge breaking minima in the CMSSM and R parity violating minima in a B-L extended MSSM., Comment: 7 pages, 2 figures, to appear in EPS-HEP 2013 conference proceedings

We study a supersymmetric version of the type-III seesaw mechanism considering two variants of the model: a minimal version for explaining neutrino data with only two copies of 24 superfields and a model with three generations of 24-plets. The latter predicts, in general, rates for mu -> e gamma inconsistent with experimental data. However, this bound can be evaded if certain special conditions within the neutrino sector are fulfilled. In the case of two 24-plets, lepton flavor violation constraints can be satisfied much more easily. After specifying the corresponding regions in the minimal supergravity parameter space, we show that under favorable conditions one can test the corresponding flavor structures in the leptonic sector at the LHC. For this we perform Monte Carlo studies for the signals, also taking into account the supersymmetry background. We find that it is only of minor importance for the scenarios studied here., We thank J. C. Romao for providing us with his SPHENO FRONTEND which facilitated the scans over the parameter space, and B. O'Leary for providing an updated version of the LHC-FASER package for the cross section calculations. W. P. and Ch. W. thank the IFIC for hospitality during extended stays. Their work has been supported in part by the DFG Project No. PO-1337/2-1 and the Helmholtz Alliance "Physics at the Terascale." W. P. has been supported by the Alexander von Humboldt Foundation. M. H. acknowledges support from the Spanish MICINN Grants No. FPA2011-22975 and No. MULTIDARK CSD2009-00064, the Generalitat Valenciana Grant No. Prometeo/2009/091, and the EU Network Grant No. UNILHC PITN-GA-2009-237920.

The SUSY Les Houches Accord (SLHA) 2 extended the first SLHA to include various generalisations of the Minimal Supersymmetric Standard Model (MSSM) as well as its simplest next-to-minimal version. Here, we propose further extensions to it, to include the most general and well-established see-saw descriptions (types I/II/III, inverse, and linear) in both an effective and a simple gauged extension of the MSSM framework. In addition, we generalise the PDG numbering scheme to reflect the properties of the particles, We would like to thank the organisers of the Les Houches 2011 “Physics at TeV colliders” workshop where this project has started. We also want to thank Nazila Mahmoudi for the enlightening comments about FLHA. L.B., A.B. and S.M. thank the NExT Institute and Royal Society for partial financial support. L.B. has also been partially supported by the Deutsche Forschungsgem einschaft through the Research Training Group GRK1102 Physics of Hadron Accelerators. S.K. acknowledges partial support from the Leverhulme Trust under the grant VP2-2011-012. B.O.L and W.P. are supporte d by the German Ministry of Education and Research (BMBF) under contract no. 05H09WWEF

We present general model-independent formulae for the branching ratios and the direct tagged CP asymmetries for the inclusive $\bar B \rightarrow X_d\, \gamma$ and $\bar B \rightarrow X_s\, \gamma$ modes. We also update the corresponding SM predictions. PACS: 12.38.Cy – 13.66.Jn – 13.20.He – 11.30.Er

We discuss the minimal supersymmetric $U(1)_{B-L}\times U(1)_R$ extension of the standard model. Gauge couplings unify as in the MSSM, even if the scale of $U(1)_{B-L}\times U(1)_R$ breaking is as low as order TeV and the model can be embedded into an SO(10) grand unified theory. The phenomenology of the model differs in some important aspects from the MSSM, leading potentially to rich phenomenology at the LHC. It predicts more light Higgs states and the mostly left CP-even Higgs has a mass reaching easily 125 GeV, with no constraints on the SUSY spectrum. Right sneutrinos can be the lightest supersymmetric particle, changing all dark matter constraints on SUSY parameter space. The model has seven neutralinos and squark/gluino decay chains involve more complicated cascades than in the MSSM. We also discuss briefly low-energy and accelerator constraints on the model, where the most important limits come from recent $Z'$ searches at the LHC and upper limits on lepton flavour violation.