The Higgs mass in the CP violating MSSM,NMSSM and beyond

We discuss the automatised calculation of the Higgs mass in renormalisable supersymmetric models with complex parameters at the two-loop level. Our setup is based on the public codes SARAH and SPheno, which can now compute the two-loop corrections to masses of all neutral scalars in such theories. The generic ansatz for these calculations and the handling of the ‘Goldstone Boson catastrophe’ is described. It is shown that we find perfect agreement with other existing two-loop calculations performed in the \(\overline{\mathrm {DR}}\) scheme. We also use the functionality to derive results for the MSSM and NMSSM not available before: the Higgs mass in the constrained version of the complex MSSM and the impact of CP phases in the two-loop corrections beyond \(O(\alpha _s \alpha _t)\) for the scale-invariant NMSSM are briefly analysed.     

Strangephilic Higgs bosons in the MSSM

We suggest a new CPX-derived scenario for the search for strangephilic MSSM Higgs bosons at the Tevatron and the LHC, in which all neutral and charged Higgs bosons decay predominantly into pairs of strange quarks and into a strange and a charm quark, respectively. The proposed scenario is realized within a particular region of the MSSM parameter space and requires large values of tan?β, where threshold radiative corrections are significant to render the effective strange-quark Yukawa coupling dominant. Experimental searches for neutral Higgs bosons based on the identification of b-quark jets or τ leptons may miss a strangephilic Higgs boson and its existence could be inferred indirectly by searching for hadronically decaying charged Higgs bosons. Potential strategies and experimental challenges to search for strangephilic Higgs bosons at the Tevatron and the LHC are discussed.     

Search for heavy neutral MSSM Higgs bosons with CMS: reach and Higgs mass precision

The search for MSSM Higgs bosons will be an important goal at the LHC. We analyze the search reach of the CMS experiment for the heavy neutral MSSM Higgs bosons with an integrated luminosity of 30 or 60 fb^-1. This is done by combining the latest results for the CMS experimental sensitivities based on full simulation studies with state-of-the-art theoretical predictions of the MSSM Higgs-boson properties. The results are interpreted in MSSM benchmark scenarios in terms of the parameters tan β and the Higgs-boson mass scale, M_A. We study the dependence of the 5σ discovery contours in the M_A–tan β plane on variations of the other supersymmetric parameters. The largest effects arise from a change in the higgsino mass parameter μ, which enters both via higher-order radiative corrections and via the kinematics of Higgs decays into supersymmetric particles. While the variation of μ can shift the prospective discovery reach (and correspondingly the ”LHC wedge” region) by about Δtan β=10, we find that the discovery reach is rather stable with respect to the impact of other supersymmetric parameters. Within the discovery region we analyze the accuracy with which the masses of the heavy neutral Higgs bosons can be determined. We find that an accuracy of 1–4% should be achievable, which could make it possible in favorable regions of the MSSM parameter space to experimentally resolve the signals of the two heavy MSSM Higgs bosons at the LHC.     

Precise prediction for the mass of the lightest Higgs boson in the MSSM

The leading diagrammatic two-loop corrections are incorporated into the prediction for the mass of the lightest Higgs boson, m_h, in the Minimal Supersymmetric Standard Model (MSSM). The results, containing the complete diagrammatic one-loop corrections, the new two-loop result and refinement terms incorporating leading electroweak two-loop and higher-order QCD contributions, are discussed and compared with results obtained by renormalization group calculations. Good agreement is found in the case of vanishing mixing in the scalar quark sector, while sizable deviations occur if squark mixing is taken into account.     

SUSY spectrum and the Higgs mass in the BLMSSM

The predictions for the mass of the light CP-even Higgs are investigated in the context of a simple extension of the Minimal Supersymmetric Standard Model where the baryon and lepton numbers are local gauge symmetries. This theory predicts the existence of light charged and neutral leptons which give extra contributions to the Higgs mass at the one-loop level. We show the possibility to satisfy the LEP2 bound and achieve a Higgs mass around 125 GeV in a supersymmetric spectrum with light sfermions and small left–right mixing in the stop sector. We make a brief discussion of the unique leptonic signals at the Large Hadron Collider. This theory predicts baryon number violation at the low scale and one could avoid the current LHC bounds on the supersymmetric mass spectrum.     

The light CP-even MSSM Higgs mass resummed to fourth logarithmic order

We present the calculation of the light neutral CP-even Higgs mass in the MSSM for a heavy SUSY spectrum by resumming enhanced terms through fourth logarithmic order (N\(^{3}\)LL), keeping terms of leading order in the top Yukawa coupling \(\alpha _t\), and NNLO in the strong coupling \(\alpha _s\). To this goal, the three-loop matching coefficient for the quartic Higgs coupling of the SM to the MSSM is derived to order \(\alpha _t^2\alpha _s^2\) by comparing the perturbative EFT to the fixed-order expression for the Higgs mass. The new matching coefficient is made available through an updated version of the program Himalaya. Numerical effects of the higher-order resummation are studied using specific examples, and sources of theoretical uncertainty on this result are discussed.     

MSSM Higgs sector at the one-loop level

This work provides an elementary introduction to the Higgs sector renormalisation within the Minimal Supersymmetric Standard Model (MSSM) framework. The main aim of the paper is to clarify some technical details that are usually omitted in the existing literature. The MSSM tree-level relation m _h ² + m _H ² = m _A ² + m _Z ² is renormalised using the standard technique of direct computation of the relevant one-loop Feynman diagrams. The calculation is performed within the unitary gauge and the definition of the renormalised parameters is briefly reviewed. The expected cancellation of ultraviolet divergences is explicitly checked and the well-known leading-log term is recovered. All the necessary ingredients of the computations are summarized in the appendices which makes the work more self-contained.     

Interpreting the LHC Higgs search results in the MSSM

Recent results reported by the ATLAS and CMS experiments on the search for a SM-like Higgs boson both show an excess for a Higgs mass near 125 GeV, which is mainly driven by the γγ   and ZZ^?$Z{Z}^{?}$ decay channels, but also receives some support from channels with a lower mass resolution. We discuss the implications of this possible signal within the context of the minimal supersymmetric Standard Model (MSSM), taking into account previous limits from Higgs searches at LEP, the Tevatron and the LHC. The consequences for the remaining MSSM parameter space are investigated. Under the assumption of a Higgs signal we derive new lower bounds on the tree-level parameters of the MSSM Higgs sector. We also discuss briefly an alternative interpretation of the excess in terms of the heavy CP-even Higgs boson, a scenario which is found to be still viable.     

Towards high-precision predictions for the MSSM Higgs sector

The status of the evaluation of the MSSM Higgs sector is reviewed. The phenomenological impact of recently obtained corrections is discussed. In particular it is shown that the upper bound on m_h within the MSSM is shifted upwards. Consequently, lower limits on obtained by confronting the upper bound as function of with the lower bound on m_h from Higgs searches are significantly weakened. Furthermore, th e region in the M_A--plane where the coupling of the lightest Higgs boson to down-type fermions is suppressed is modified. The presently not calculated higher-order corrections to the Higgs-boson mass matrix are estimated to shift the mass of the lightest Higgs boson by up to 3 GeV. Received: 12 December 2002 / Published online: 3 March 2003 RID="a" ID="a" e-mail: giuseppe.degrassi@roma3.infn.it RID="b" ID="b" e-mail: Sven.Heinemeyer@physik.uni-muenchen.de RID="c" ID="c" e-mail: hollik@mppmu.mpg.de RID="d" ID="d" e-mail: slavich@mppmu.mpg.de RID="e" ID="e" e-mail: Georg.Weiglein@durham.ac.uk     

Constraints on the MSSM from the Higgs sector

We discuss the constraints on supersymmetry in the Higgs sector arising from LHC searches, rare B decays and dark matter direct detection experiments. We show that constraints derived on the mass of the lightest h ⁰ and the CP-odd A ⁰ bosons from these searches are covering a larger fraction of the SUSY parameter space compared to searches for strongly interacting supersymmetric particle partners. We discuss the implications of a mass determination for the lightest Higgs boson in the range 123<M _h <127?GeV, inspired by the intriguing hints reported by the ATLAS and CMS Collaborations, as well as those of a non-observation of the lightest Higgs boson for MSSM scenarios not excluded at the end of 2012 by LHC and direct dark matter searches and their implications on LHC SUSY searches.     

Complete one-loop corrections to the mass spectrum of charginos and neutralinos in the MSSM

The mass spectrum of the chargino–neutralino sector in the minimal supersymmetric standard model (MSSM) is calculated at the one-loop level, based on the complete set of one-loop diagrams. On-shell renormalization conditions are applied to determine the counterterms for the gaugino-mass-parameters and the Higgsino-mass parameter . The input is fixed in terms of three pole masses (two charginos and one neutralino); the other pole masses receive a shift with respect to the tree-level masses, which can amount to several GeV. The detailed evaluation shows that both the fermionic/sfermionic loop contributions and the non-(s)fermionic loop contributions are of the same order of magnitude and are thus relevant for precision studies at future colliders. Received: 26 April 2002 / Published online: 21 June 2002     

Charged Higgs bosons in the next-to MSSM (NMSSM)

The charged Higgs boson decays H^±→W^±A₁ and H^±→W^±H_i are studied in the framework of the next-to-minimal supersymmetric standard model (NMSSM). It is found that the decay rate for H^±→W^±A₁ can exceed the rates for the τ^±ν and tb channels both below and above the top–bottom threshold. The dominance of H^±→W^±A₁ is most readily achieved when A₁ has a large doublet component and small mass. We also study the production process pp→H^±A₁ at the LHC followed by the decay H^±→W^±A₁, which leads to the signature W^±A₁A₁. We suggest that pp→H^±A₁ is a promising discovery channel for a light charged Higgs boson in the NMSSM with small or moderate tanβ and dominant decay mode H^±→W^±A₁. This W^±A₁A₁ signature can also arise from the Higgsstrahlung process pp→W^±H₁ followed by the decay H₁→A₁A₁. It is shown that there exist regions of parameter space where these processes can have comparable cross sections and we suggest that their respective signals can be distinguished at the LHC by using appropriate reconstruction methods. PACS  12.60.Fr; 14.80.Cp     

The Higgs sector of the MSSM in the decoupling limit

We study the heavy Higgs sector of the MSSM composed of the and particles in the so-called decoupling limit where . By integrating out these heavy Higgs particles to one-loop, we compute the effective action for the electroweak gauge bosons and find out that, in the decoupling limit, all the heavy Higgs effects can be absorbed into redefinitions of the Standard Model electroweak parameters. This demonstrates explicitely that the decoupling theorem works for the heavy MSSM Higgs particles. This is also compared with the paradigmatic and different case of the Standard Model heavy Higgs particle. Finally, this work together with our two previous works, complete the demonstration that all the non-standard particles in the MSSM, namely, squarks, sleptons, charginos, neutralinos and the heavy Higgs particles, decouple to one-loop from the low energy electroweak gauge boson physics. Received: 2 March 2000 / Revised version: 13 July 2000 / Published online: 8 September 2000     

Higgs bosons in the standard model,the MSSM and beyond

I summarize the basic theory and selected phenomenology for the Higgs boson(s) of the standard model, the minimal supersymmetric model and some extensions thereof, including the next-to-minimal supersymmetric model.     

MSSM Higgs searches in multi-b-jet final states at the LHC

This paper discusses the possibility to observe a signal from MSSM Higgs boson decays into final states containing four b-jets. Two specific channels are considered: bb?H and bb?A production with H,A → bb?, for large values of m_H, m_A and tan β, and H → hh → bb?bb? decays for 150 GeV < m_H < 2m_t and for low values of tan β. Both channels are difficult to extract because of the very large reducible and irreducible QCD backgrounds. Even with an ultimate integrated luminosity, expected per LHC experiment, of 3 · 10⁵ pb^-1, the region of the MSSM parameter space covered by these channels does not extend the reach beyond that accessible to other channels that were studied in the past. Nevertheless, their observation would help in constraining the couplings and branching ratios of the MSSM Higgs bosons.     

Effective action for the standard model with large Higgs mass

The covariant derivative expansion of the one-loop effective action is briefly reviewed, and applied to the problem of calculating the heavy Higgs effects in the standard Glashow-Weinberg-Salam model. All terms which grow with the Higgs mass M_H at one loop are found. The result of this calculation is used to find the dependence of the gauge boson mass ratio ϱ on M_H, and also to estimate the size of corrections to W and Z scattering theorems.     

On the NLO QCD corrections to Higgs production and decay in the MSSM

We present explicit analytic results for the two-loop top/stop/gluino contributions to the cross section for the production of CP-even Higgs bosons via gluon fusion in the MSSM, under the approximation of neglecting the Higgs boson mass with respect to the masses of the particles circulating in the loops. The results are obtained employing the low-energy theorem for Higgs interactions adapted to the case of particle mixing. We discuss the validity of the approximation used by computing the first-order correction in an expansion in powers of the Higgs boson mass. We find that, for the lightest CP-even Higgs boson, the gluino contribution is very well approximated by the result obtained in the limit of vanishing Higgs mass. As a byproduct of our calculation, we provide results for the two-loop QCD contributions to the photonic Higgs decay.