# S. Hesselbach - IPPP, University of Durham, UK

## Contact Details

NameS. Hesselbach |
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AffiliationIPPP, University of Durham, UK |
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CityDurham |
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CountryUnited Kingdom |
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## Pubs By Year |
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## Pub CategoriesHigh Energy Physics - Phenomenology (49) High Energy Physics - Experiment (5) Physics - Accelerator Physics (1) |

## Publications Authored By S. Hesselbach

We study the effect of explicit CP violation in the Higgs sectors of the MSSM in the di-photon decay of the lightest CP-mixed Higgs state. Further it is shown that the gluon fusion production mechanism along with the di-photon decay enhances CP-violating effects for a large set of suitably chosen parameter values. Read More

We analysed the sensitivity of the process gg to H_1 to gamma-gamma to the explicitly CP-violating phases phi_mu and phi_{A_f} in the Minimal Supersymmetric Standard Model (MSSM) at the Large Hadron Collider (LHC), where H_1 is the lightest Supersymmetric Higgs boson. We conclude that depending on these phases, the overall production and decay rates of H_1 can vary up to orders of magnitude compared to the CP-conserving case. Read More

**Authors:**B. Aurand, I. Bailey, C. Bartels, A. Brachmann, J. Clarke, A. Hartin, J. Hauptman, C. Helebrant, S. Hesselbach, D. Kafer, J. List, W. Lorenzon, I. Marchesini, K. Monig, K. C. Moffeit, G. Moortgat-Pick, S. Riemann, A. Schalicke, P. Schuler, P. Starovoitov, A. Ushakov, U. Velte, J. Wittschen, M. Woods

**Category:**Physics - Accelerator Physics

In this contribution accelerator solutions for polarized beams and their impact on physics measurements are discussed. Focus are physics requirements for precision polarimetry near the interaction point and their realization with polarized sources. Based on the ILC baseline programme as described in the Reference Design Report (RDR), recent developments are discussed and evaluated taking into account physics runs at beam energies between 100 GeV and 250 GeV, as well as calibration runs on the Z-pole and options as the 1TeV upgrade and GigaZ. Read More

**Affiliations:**

^{1}IPPP, University of Durham, UK,

^{2}University of Southampton, UK,

^{3}Instituto de Fisica, Mexico,

^{4}IIT Guwahati, India

**Category:**High Energy Physics - Phenomenology

We prove the strong sensitivity of the gg --> H1 --> gamma.gamma cross section at the Large Hadron Collider on the explicitly CP-violating phases of the Minimal Supersymmetric Standard Model, where H1 is the lightest Supersymmetric Higgs boson. Read More

We argue that the allowed range of the mass of the lightest neutralino in the MNSSM is limited. We establish the theoretical upper bound on the lightest neutralino mass and obtain an approximate solution for this mass. Read More

**Authors:**Alexander Belyaev

^{1}, Stefan Hesselbach

^{2}, Sami Lehti

^{3}, Stefano Moretti

^{4}, Alexander Nikitenko

^{5}, Claire H. Shepherd-Themistocleous

^{6}

**Affiliations:**

^{1}University of Southampton,

^{2}University of Durham,

^{3}Helsinki Institute of Physics,

^{4}University of Southampton,

^{5}Imperial College,

^{6}Rutherford Appleton Laboratory

We study the potential of the h_1 -> a_1 a_1 -> 4 tau signal from the lightest scalar (h_1) and pseudoscalar (a_1) Higgs bosons to cover the parameter space of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) at the Large Hadron Collider (LHC). We exploit a 2 mu + 2 jets signature from four taus decays (accompanied by missing transverse energy), resorting to both Higgs-strahlung (HS), by triggering on leptonic W^\pm decays, and Vector Boson Fusion (VBF), by triggering on two same sign non-isolated muons. Read More

**Authors:**S. Dawson, M. Grazzini, A. Nikitenko, M. Schumacher, N. E. Adam, T. Aziz, J. R. Andersen, A. Belyaev, T. Binoth, S. Catani, M. Ciccolini, J. E. Cole, S. Dawson, A. Denner, S. Dittmaier, A. Djouadi, M. Drees, U. Ellwanger, C. Englert, T. Figy, E. Gabrielli, D. Giordano, S. Gleyzer, R. Godbole, M. Grazzini, S. Greder, V. Halyo, M. Hashemi, S. Heinemeyer, G. Heinrich, M. Herquet, S. Hesselbach, C. Hugonie, C. B. Jackson, N. Kauer, R. Kinnunen, S. F. King, S. Lehti, F. Maltoni, B. Mele, P. Mertsch, M. Moretti, S. Moretti, M. Muhlleitner, A. K. Nayak, A. Nikitenko, C. Oleari, F. Piccinini, R. Pittau, J. Rathsman, I. Rottlaender, C. H. Shepherd-Themistocleous, M. Schumacher, J. M. Smillie, A. Sopczak, M. Spira, M. Takahashi, A. M. Teixeira, I. R. Tomalin, M. Vazquez Acosta, G. Weiglein, C. D. White, D. Zeppenfeld

**Category:**High Energy Physics - Phenomenology

Report of the Working Group on Higgs Bosons for the Workshop, ``Physics at TeV Colliders'', Les Houches, France, 11-29 June, 2007. Read More

We study the neutralino sector of the Minimal Non-minimal Supersymmetric Standard Model (MNSSM) where the $\mu$ problem of the Minimal Supersymmetric Standard Model (MSSM) is solved without accompanying problems related with the appearance of domain walls. In the MNSSM as in the MSSM the lightest neutralino can be the absolutely stable lightest supersymmetric particle (LSP) providing a good candidate for the cold dark matter component of the Universe. In contrast with the MSSM the allowed range of the mass of the lightest neutralino in the MNSSM is limited. Read More

We consider the neutralino sector in the Minimal Non--minimal Supersymmetric Standard Model (MNSSM). We argue that there exists a theoretical upper bound on the lightest neutralino mass in the MNSSM. An approximate solution for the mass of the lightest neutralino is obtained. Read More

**Affiliations:**

^{1}University of Southampton,

^{2}University of Southampton,

^{3}University of Southampton,

^{4}University of Southampton

**Category:**High Energy Physics - Phenomenology

Physical Higgs particles in the Minimal Supersymmetric Standard Model (MSSM) with explicit CP violation are CP mixed states. The decay of these Higgs particles can be analysed to study the CP properties of the MSSM. In the present work we consider the di-photon channel of the lightest neutral Higgs boson for this purpose. Read More

We investigate the associated production of charged Higgs bosons (H^\pm) and W bosons at the CERN Large Hadron Collider, using the leptonic decay H^+ -> tau^+ nu_tau and hadronic W decay, within different scenarios of the Minimal Supersymmetric Standard Model (MSSM) with both real and complex parameters. Performing a parton level study we show how the irreducible Standard Model background from W + 2 jets can be controlled by applying appropriate cuts. In the standard m_h^max scenario we find a viable signal for large tan beta and intermediate H^\pm masses (~ m_t). Read More

We examine the allowed mass range of the lightest neutralino within the Minimal Non--minimal Supersymmetric Standard Model. Being absolutely stable if R-parity is conserved this lightest neutralino is a candidate for the dark matter of the universe. We establish the theoretical upper bound on the lightest neutralino mass and obtain an approximate solution for this mass. Read More

We investigate the viability of observing charged Higgs bosons (H^\pm) produced in association with W bosons at the CERN Large Hadron Collider, using the leptonic decay H^+ -> tau^+ nu_tau and hadronic W decay, within the Minimal Supersymmetric Standard Model. Performing a parton level study we show how the irreducible Standard Model background from W + 2 jets can be controlled by applying appropriate cuts. In the standard m_h^max scenario we find a viable signal for large tan beta and intermediate H^\pm masses (~ m_t). Read More

**Affiliations:**

^{1}University of Southampton,

^{2}University of Southampton,

^{3}University of Southampton,

^{4}University of Southampton

**Category:**High Energy Physics - Phenomenology

The Minimal Supersymmetric Standard Model (MSSM) with explicit CP violation is studied with the help of the di-photon decay channel of the lightest neutral Higgs boson. Effects of CP violation, entering via the scalar/pseudo-scalar mixing at higher order as well as through the Higgs-sfermion-sfermion couplings at tree-level, are analyzed in the MSSM with and without light sparticles. A light stop may have a strong impact on the decay width and Branching Ratio (BR) of the decay process H_1 -> gamma gamma, whereas other light sparticles have only little influence. Read More

Recent studies about CP violation in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters are reviewed. In order to unambiguously identify the CP-violating phenomena it is necessary to study CP-odd or T-odd observables. In chargino and neutralino production and decay at the International Linear Collider (ILC) triple product asymmetries and asymmetries defined via transverse beam polarization have been analyzed. Read More

**Affiliations:**

^{1}Southampton U.,

^{2}Southampton U. and Orsay, LPT,

^{3}Uppsala U.,

^{4}Uppsala U. and Lancaster U.

**Category:**High Energy Physics - Phenomenology

We report on detailed Monte Carlo comparisons of selection variables to separate tbH+ signal events from the Standard Model ttbar background using an Iterative Discriminant Analysis (IDA) method. While kinematic differences exist between the two processes whenever m(H+).ne. Read More

**Affiliations:**

^{1}University of Southampton,

^{2}University of Southampton,

^{3}University of Southampton,

^{4}University of Southampton

**Category:**High Energy Physics - Phenomenology

The di-photon decay channel of the lightest Higgs boson is considerd as a probe to explore CP violation in the Minimal Supersymmetric Standard Model (MSSM). The scalar/pseudo-scalar mixing is considered along with CP violation entering through the Higgs-sfermion-sfermion couplings, with and without light sparticles. The impact of a light stop on the decay width and Branching Ratio (BR) is established through a detailed study of the amplitude of the process H1 --> gamma. Read More

We investigate the viability of observing charged Higgs bosons (H^+/-) produced in association with W bosons at the CERN Large Hadron Collider, using the leptonic decay H^+ -> tau^+ nu_tau and hadronic W-decay, within different scenarios of the Minimal Supersymmetric Standard Model (MSSM) with both real and complex parameters. Performing a parton level study we show how the irreducible Standard Model background from W+2 jets can be controlled by applying appropriate cuts and find that the size of a possible signal depends on the cuts needed to suppress QCD backgrounds and misidentifications. In the standard maximal mixing scenario of the MSSM we find a viable signal for large tan(beta) and intermediate H^+/- masses (~m_t) when using optimistic cuts whereas for more pessimistic ones we only find a viable signal for very large tan(beta) (>~50). Read More

**Authors:**U. Aglietti, A. Belyaev, S. Berge, A. Blum, R. Bonciani, J. Cammin, M. Carena, S. Chivukula, H. Davoudiasl, S. Dawson, G. Degrassi, A. Dominguez, J. Donini, T. Dorigo, B. J. Field, T. Hahn, T. Han, S. Heinemeyer, S. Hesselbach, G. -Y. Huang, I. Iashvilli, C. B. Jackson, T. Junk, S. -W. Lee, H. E. Logan, F. Maltoni, B. Mellado, S. Moretti, S. Mrenna, P. M. Nadolsky, F. I. Olness, W. Quayle, J. Rathsman, L. Reina, E. H. Simmons, A. Sopczak, A. Vicini, D. Wackeroth, C. E. M. Wagner, G. Weiglein, G. Weiglein, S. Willenbrock, S. L. Wu, C. P. Yuan

**Category:**High Energy Physics - Phenomenology

The search for Higgs bosons in both the standard model and its extensions is well under way at the Tevatron. As the integrated luminosity collected increases into the multiple inverse femptobarn range, these searches are becoming very interesting indeed. Meanwhile, the construction of the Large Hadron Collider (LHC) and its associated experiments at CERN are nearing completion. Read More

**Authors:**S. Kraml, E. Accomando, A. G. Akeroyd, E. Akhmetzyanova, J. Albert, A. Alves, N. Amapane, M. Aoki, G. Azuelos, S. Baffioni, A. Ballestrero, V. Barger, A. Bartl, P. Bechtle, G. Belanger, A. Belhouari, R. Bellan, A. Belyaev, P. Benes, K. Benslama, W. Bernreuther, M. Besancon, G. Bevilacqua, M. Beyer, M. Bluj, S. Bolognesi, M. Boonekamp, F. Borzumati, F. Boudjema, A. Brandenburg, T. Brauner, C. P. Buszello, J. M. Butterworth, M. Carena, D. Cavalli, G. Cerminara, S. Y. Choi, B. Clerbaux, C. Collard, J. A. Conley, A. Deandrea, S. De Curtis, R. Dermisek, A. De Roeck, G. Dewhirst, M. A. Diaz, J. L. Diaz-Cruz, D. D. Dietrich, M. Dolgopolov, D. Dominici, M. Dubinin, O. Eboli, J. Ellis, N. Evans, L. Fano, J. Ferland, S. Ferrag, S. P. Fitzgerald, H. Fraas, F. Franke, S. Gennai, I. F. Ginzburg, R. M. Godbole, T. Gregoire, G. Grenier, C. Grojean, S. B. Gudnason, J. F. Gunion, H. E. Haber, T. Hahn, T. Han, V. Hankele, C. Hays, S. Heinemeyer, S. Hesselbach, J. L. Hewett, K. Hidaka, M. Hirsch, W. Hollik, D. Hooper, J. Hosek, J. Hubisz, C. Hugonie, J. Kalinowski, S. Kanemura, V. Kashkan, T. Kernreiter, W. Khater, V. A. Khoze, W. Kilian, S. F. King, O. Kittel, G. Klamke, J. L. Kneur, C. Kouvaris, M. Krawczyk, P. Krstonosic, A. Kyriakis, P. Langacker, M. P. Le, H. -S. Lee, J. S. Lee, M. C. Lemaire, Y. Liao, B. Lillie, V. Litvin, H. E. Logan, B. McElrath, T. Mahmoud, E. Maina, C. Mariotti, P. Marquard, A. D. Martin, K. Mazumdar, D. J. Miller, P. Mine, K. Moenig, G. Moortgat-Pick, S. Moretti, M. M. Muhlleitner, S. Munir, R. Nevzorov, H. Newman, P. Niezurawski, A. Nikitenko, R. Noriega-Papaqui, Y. Okada, P. Osland, A. Pilaftsis, W. Porod, H. Przysiezniak, A. Pukhov, D. Rainwater, A. Raspereza, J. Reuter, S. Riemann, S. Rindani, T. G. Rizzo, E. Ros, A. Rosado, D. Rousseau, D. P. Roy, M. G. Ryskin, H. Rzehak, F. Sannino, E. Schmidt, H. Schroder, M. Schumacher, A. Semenov, E. Senaha, G. Shaughnessy, R. K. Singh, J. Terning, L. Vacavant, M. Velasco, A. Villanova del Moral, F. von der Pahlen, G. Weiglein, J. Williams, K. Williams, A. F. Zarnecki, D. Zeppenfeld, D. Zerwas, P. M. Zerwas, A. R. Zerwekh, J. Ziethe

There are many possibilities for new physics beyond the Standard Model that feature non-standard Higgs sectors. These may introduce new sources of CP violation, and there may be mixing between multiple Higgs bosons or other new scalar bosons. Alternatively, the Higgs may be a composite state, or there may even be no Higgs at all. Read More

We study CP violation in chargino production and decay in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters at an e^+ e^- linear collider with longitudinally polarized beams. We investigate CP-sensitive asymmetries by means of triple product correlations and study their dependence on the complex parameters M_1 and mu. We give numerical predictions for the asymmetries and their measurability at the future International Linear Collider. Read More

**Authors:**B. C. Allanach

^{1}, C. Grojean

^{2}, P. Skands

^{3}, E. Accomando, G. Azuelos, H. Baer, C. Balazs, G. Belanger, K. Benakli, F. Boudjema, B. Brelier, V. Bunichev, G. Cacciapaglia, M. Carena, D. Choudhury, P. -A. Delsart, U. De Sanctis, K. Desch, B. A. Dobrescu, L. Dudko, M. El Kacimi, U. Ellwanger, S. Ferrag, A. Finch, F. Franke, H. Fraas, A. Freitas, P. Gambino, N. Ghodbane, R. M. Godbole, D. Goujdami, Ph. Gris, J. Guasch, M. Guchait, T. Hahn, S. Heinemeyer, A. Hektor, S. Hesselbach, W. Hollik, C. Hugonie, T. Hurth, J. Idarraga, O. Jinnouchi, J. Kalinowski, J. -L. Kneur, S. Kraml, M. Kadastik, K. Kannike, R. Lafaye, G. Landsberg, T. Lari, J. S. Lee, J. Lykken, F. Mahmoudi, M. Mangano, A. Menon, D. J. Miller, T. Millet, C. Milstene, S. Montesano, F. Moortgat, G. Moortgat-Pick, S. Moretti, D. E. Morrissey, S. Muanza, M. M. Muhlleitner, M. Muntel, H. Nowak, T. Ohl, S. Penaranda, M. Perelstein, E. Perez, S. Perries, M. Peskin, J. Petzoldt, A. Pilaftsis, T. Plehn, G. Polesello, A. Pompos, W. Porod, H. Przysiezniak, A. Pukhov, M. Raidal, D. Rainwater, A. R. Raklev, J. Rathsman, J. Reuter, P. Richardson, S. D. Rindani, K. Rolbiecki, H. Rzehak, M. Schumacher, S. Schumann, A. Semenov, L. Serin, G. Servant, C. H. Shepherd-Themistocleous, S. Sherstnev, L. Silvestrini, R. K. Singh, P. Slavich, M. Spira, A. Sopczak, K. Sridhar, L. Tompkins, C. Troncon, S. Tsuno, K. Wagh, C. E. M. Wagner, G. Weiglein, P. Wienemann, D. Zerwas, V. Zhukov

**Affiliations:**

^{1}ed.,

^{2}ed.,

^{3}ed.

**Category:**High Energy Physics - Phenomenology

The work contained herein constitutes a report of the "Beyond the Standard Model'' working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 2-20 May, 2005. We present reviews of current topics as well as original research carried out for the workshop. Supersymmetric and non-supersymmetric models are studied, as well as computational tools designed in order to facilitate their phenomenology. Read More

**Authors:**J. A. Aguilar-Saavedra, A. Ali, B. C. Allanach, R. Arnowitt, H. A. Baer, J. A. Bagger, C. Balazs, V. Barger, M. Barnett, A. Bartl, M. Battaglia, P. Bechtle, G. Belanger, A. Belyaev, E. L. Berger, G. Blair, E. Boos, M. Carena, S. Y. Choi, F. Deppisch, A. De Roeck, K. Desch, M. A. Diaz, A. Djouadi, B. Dutta, S. Dutta, H. Eberl, J. Ellis, J. Erler, H. Fraas, A. Freitas, T. Fritzsche, R. M. Godbole, G. J. Gounaris, J. Guasch, J. Gunion, N. Haba, H. E. Haber, K. Hagiwara, L. Han, T. Han, H. -J. He, S. Heinemeyer, S. Hesselbach, K. Hidaka, I. Hinchliffe, M. Hirsch, K. Hohenwarter-Sodek, W. Hollik, W. S. Hou, T. Hurth, I. Jack, Y. Jiang, D. R. T. Jones, J. Kalinowski, T. Kamon, G. Kane, S. K. Kang, T. Kernreiter, W. Kilian, C. S. Kim, S. F. King, O. Kittel, M. Klasen, J. -L. Kneur, K. Kovarik, M. Kramer, S. Kraml, R. Lafaye, P. Langacker, H. E. Logan, W. -G. Ma, W. Majerotto, H. -U. Martyn, K. Matchev, D. J. Miller, M. Mondragon, G. Moortgat-Pick, S. Moretti, T. Mori, G. Moultaka, S. Muanza, M. M. Muhlleitner, B. Mukhopadhyaya, U. Nauenberg, M. M. Nojiri, D. Nomura, H. Nowak, N. Okada, K. A. Olive, W. Oller, M. Peskin, T. Plehn, G. Polesello, W. Porod, F. Quevedo, D. Rainwater, J. Reuter, P. Richardson, K. Rolbiecki, P. Roy, R. Ruckl, H. Rzehak, P. Schleper, K. Siyeon, P. Skands, P. Slavich, D. Stockinger, P. Sphicas, M. Spira, T. Tait, D. R. Tovey, J. W. F. Valle, C. E. M. Wagner, Ch. Weber, G. Weiglein, P. Wienemann, Z. -Z. Xing, Y. Yamada, J. M. Yang, D. Zerwas, P. M. Zerwas, R. -Y. Zhang, X. Zhang, S. -H. Zhu

**Category:**High Energy Physics - Phenomenology

High-precision analyses of supersymmetry parameters aim at reconstructing the fundamental supersymmetric theory and its breaking mechanism. A well defined theoretical framework is needed when higher-order corrections are included. We propose such a scheme, Supersymmetry Parameter Analysis SPA, based on a consistent set of conventions and input parameters. Read More

**Authors:**S. Heinemeyer, S. Kanemura, H. Logan, A. Raspereza, T. Tait, H. Baer, E. L. Berger, A. Birkedal, J. -C. Brient, M. Carena, J. A. R. Cembranos, S. Choi, S. Godfrey, J. Gunion, H. E. Haber, T. Han, H. Heath, S. Hesselbach, J. Kalinowski, W. Kilian, G. Moortgat-Pick, S. Moretti, S. Mrenna, M. Muhlleitner, F. Petriello, J. Reuter, M. Ronan, P. Skands, A. Sopczak, M. Spira, Z. Sullivan, C. Wagner, G. Weiglein, P. Zerwas

**Category:**High Energy Physics - Phenomenology

This report reviews the properties of Higgs bosons in the Standard Model (SM) and its various extensions. We give an extensive overview about the potential of the ILC operated at centre-of-mass energies up to 1 TeV (including the gamma gamma option) for the determination of the Higgs boson properties. This comprises the measurement of the Higgs boson mass, its couplings to SM fermions and gauge bosons, and the determination of the spin and the CP quantum numbers of the Higgs. Read More

We consider neutralino production and decay e^+e^ --> chi^0_i chi^0_j, chi^0_j --> chi^0_1 f \bar{f} at a linear collider with transverse e^+ and e^- beam polarization. We propose CP asymmetries by means of the azimuthal distribution of the produced neutralinos and of that of the final leptons, while taking also into account the subsequent decays of the neutralinos. We include the complete spin correlations between production and decay. Read More

The interplay between the LHC and the $e^+ e^-$ International Linear Collider (ILC) with $\sqrt{s}=500$ GeV might be crucial for the discrimination between the minimal and next-to-minimal supersymmetric standard model. We present an NMSSM scenario, where the light neutralinos have a significant singlino component, that cannot be distinguished from the MSSM by cross sections and mass measurements. Mass and mixing state predictions for the heavier neutralinos from the ILC analysis at different energy stages and comparison with observation at the LHC, lead to clear identification of the particle character and identify the underlying supersymmetric model. Read More

**Authors:**G. Moortgat-Pick, T. Abe, G. Alexander, B. Ananthanarayan, A. A. Babich, V. Bharadwaj, D. Barber, A. Bartl, A. Brachmann, S. Chen, J. Clarke, J. E. Clendenin, J. Dainton, K. Desch, M. Diehl, B. Dobos, T. Dorland, H. Eberl, J. Ellis, K. FlÃ¶ttmann, H. Fraas, F. Franco-Sollova, F. Franke, A. Freitas, J. Goodson, J. Gray, A. Han, S. Heinemeyer, S. Hesselbach, T. Hirose, K. Hohenwarter-Sodek, J. Kalinowski, T. Kernreiter, O. Kittel, S. Kraml, W. Majerotto, A. Martinez, H. -U. Martyn, W. Menges, A. Mikhailichenko, K. MÃ¶nig, K. Moffeit, S. Moretti, O. Nachtmann, F. Nagel, T. Nakanishi, U. Nauenberg, T. Omori, P. Osland, A. A. Pankov, N. Paver, R. Pitthan, R. PÃ¶schl, W. Porod, J. Proulx, P. Richardson, S. Riemann, S. D. Rindani, T. G. Rizzo, P. SchÃ¼ler, C. Schwanenberger, D. Scott, J. Sheppard, R. K. Singh, H. Spiesberger, A. Stahl, H. Steiner, A. Wagner, G. Weiglein, G. W. Wilson, M. Woods, P. Zerwas, J. Zhang, F. Zomer

**Category:**High Energy Physics - Phenomenology

The proposed International Linear Collider (ILC) is well-suited for discovering physics beyond the Standard Model and for precisely unraveling the structure of the underlying physics. The physics return can be maximized by the use of polarized beams. This report shows the paramount role of polarized beams and summarizes the benefits obtained from polarizing the positron beam, as well as the electron beam. Read More

We show that the interplay between the LHC and the e^+ e^- International Linear Collider (ILC) with sqrt{s}=500 GeV might be crucial for the discrimination between the minimal and next-to-minimal supersymmetric standard model. We present an NMSSM scenario that cannot be distinguished from the MSSM by cross sections and mass measurements if only the light neutralinos and the lightest chargino are kinematically accessible, even if one of the neutralinos has a significant singlino component. Mass predictions for the heavier neutralinos from the ILC analysis and their observation at the LHC lead to an identification of the neutralino mixing character and the underlying supersymmetric model in a combined LHC/ILC analysis. Read More

**Category:**High Energy Physics - Phenomenology

We first discuss the basic features of electroweak 1-loop corrections in the Standard Model. We also give a short and elementary review on Higgs boson searches, grand unification, supersymmetry and extra dimensions. Read More

We review our recent studies on the effects of CP-violating supersymmetric (SUSY) parameters on the phenomenology of neutralinos, charginos and third generation squarks. The CP-even branching ratios of the squarks show a pronounced dependence on the phases of A_t, A_b, mu and M_1 in a large region of the supersymmetric parameter space, which can be used to get information on these phases. In addition we have studied CP-odd observables, like asymmetries based on triple product correlations. Read More

Recent studies about the impact of the CP-violating complex parameters in supersymmetry on the decays of third generation squarks and about T-odd asymmetries in neutralino and chargino production and decay are reviewed. The CP-even branching ratios of the third generation squarks show a pronounced dependence on the phases of A_t, A_b, mu and M_1 in a large region of the supersymmetric parameter space. This could have important implications for stop and sbottom searches and the MSSM parameter determination in future collider experiments. Read More

**Affiliations:**

^{1}Vienna U.,

^{2}Vienna U.,

^{3}Tokyo Gakugei U.,

^{4}Vienna U.,

^{5}Zurich U.

**Category:**High Energy Physics - Phenomenology

We study the decays of top squarks (~t_{1,2}) and bottom squarks (~b_{1,2}) in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters A_t, A_b, mu and M_1. We show that including the corresponding phases strongly affects the branching ratios of ~t_{1,2} and ~b_{1,2} decays in a large domain of the MSSM parameter space. This could have an important impact on the search for ~t_{1,2} and ~b_{1,2} and the determination of the underlying MSSM parameters at future colliders. Read More

A review about some recent studies on the determination of the CP-violating complex parameters in supersymmetry at an e^+ e^- linear collider is presented. CP-even observables, like masses, cross sections and branching ratios, can have a strong dependence on the supersymmetric phases. However, CP-odd observables, like asymmetries based on triple product correlations, are necessary to unambiguously establish CP violation. Read More

We review some recent studies about the parameter determination of top quarks, W bosons, Higgs bosons, supersymmetric particles and in the ADD model of extra dimensions at a linear collider. Read More

We study CP-violating effects in neutralino production and subsequent decay within the Minimal Supersymmetric Standard Model with complex parameters M_1 and mu. The observable we propose is a T-odd asymmetry based on a triple product in neutralino production e^+ e^- -> tilde{chi}^0_i tilde{chi}^0_2, i = 1,.. Read More

We report on the results of a phenomenological study of top squarks (stop_{1,2}) and bottom squarks (sbottom_{1,2}) in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters A_t, A_b, mu and M_1. In particular we focus on the CP phase dependence of the branching ratios of stop_{1,2} and sbottom_{1,2} decays. We find that the effect of the phases on the stop_{1,2} and sbottom_{1,2} decays can be quite significant in a large region of the MSSM parameter space. Read More

We present a phenomenological study of top squarks (~t_1,2) and bottom squarks (~b_1,2) in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters A_t, A_b, \mu and M_1. In particular we focus on the CP phase dependence of the branching ratios of (~t_1,2) and (~b_1,2) decays. We give the formulae of the two-body decay widths and present numerical results. Read More

Several results obtained within the SUSY group of the ECFA/DESY linear collider study are presented: (i) a possibility to determine tan beta and the trilinear couplings A_f via polarisation in sfermion decays, (ii) the impact of complex MSSM parameters on the third generation sfermion decays, (iii) determination of CP violation in the complex MSSM via T-odd asymmetries in neutralino production and decay, and (iv) an analysis of the chargino and neutralino mass parameters at one-loop level. Read More

**Affiliations:**

^{1}Vienna U.,

^{2}Vienna U.,

^{3}Tokyo Gakugei U.,

^{4}Vienna U.,

^{5}Zurich U.

We study the decays of top squarks (stop_{1,2}) and bottom squarks (sbottom_{1,2}) in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters A_t, A_b, mu and M_1. We show that including the corresponding phases substantially affects the branching ratios of stop_{1,2} and sbottom_{1,2} decays in a large domain of the MSSM parameter space. We find that the branching ratios can easily change by a factor of 2 and more when varying the phases. Read More

We study the decays of top squarks and bottom squarks in the Minimal Supersymmetric Standard Model with complex parameters A_t, A_b and mu. In a large region of the supersymmetric parameter space the branching ratios of stop_1 and sbottom_1 show a pronounced phase dependence. This could have an important impact on the search for stop_1 and sbottom_1 at a future linear collider and on the determination of the supersymmetric parameters. Read More

**Authors:**A. Freitas, J. Kalinowski, B. Ananthanarayan, A. Bartl, G. A. Blair, C. Blochinger, E. Boos, A. Brandenburg, A. Datta, A. Djouadi, H. Fraas, J. Guasch, S. Hesselbach, K. Hidaka, W. Hollik, T. Kernreiter, M. Maniatis, A. v. Manteuffel, H. U. Martyn, D. J. Miller, G. Moortgat-Pick, M. Muhlleitner, U. Nauenberg, H. Nowak, W. Porod, J. Sola, A. Sopczak, A. Stahl, M. M. Weber, P. M. Zerwas

At future e+- e- linear colliders, the event rates and clean signals of scalar fermion production - in particular for the scalar leptons - allow very precise measurements of their masses and couplings and the determination of their quantum numbers. Various methods are proposed for extracting these parameters from the data at the sfermion thresholds and in the continuum. At the same time, NLO radiative corrections and non-zero width effects have been calculated in order to match the experimental accuracy. Read More

We adopt the SUSY benchmark scenario SPS 1a in supersymmetric models where the Higgs sector is extended by singlet superfields. We consider light neutralinos with dominant singlino character whose couplings are generally suppressed. The cross sections for direct production of the singlino-dominated neutralinos can be of the order of several fb for singlet vevs of some TeV. Read More

Neutralinos with a large singlino component may appear in extended supersymmetric models with additional singlet Higgs fields. Since singlinos do not couple to (s)fermions and gauge bosons, the cross sections for the production of singlino dominated neutralinos are generally small. Within the framework of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) and an E_6 inspired model we study neutralino production e^+ e^- --> neutralino_1 neutralino_2 (neutralino_1,2 neutralino_3) with a singlino dominated neutralino_2 (neutralino_3). Read More

An R-parity violating SUSY model with lepton-number violating couplings $\lambda'_{i33}$, i=2,3 can generate a neutrino mass spectrum that explains the recent results from neutrino oscillation experiments. These R-parity violating couplings lead to a clean signal with at least one isolated lepton and at least three tagged $b$ jets that is accessible in chargino and neutralino production at the Tevatron collider. This signature can be probed at $3 \sigma$ up to $m_{1/2} = 230$ GeV (320 GeV) with an integrated luminosity of $2 fb^{-1}$ ($30 fb^{-1}$). Read More

The neutralino sector in E_6 inspired supersymmetric models with extra neutral gauge bosons and singlet Higgs fields contains additional gaugino and singlino states compared to the MSSM. We discuss the neutralino mixing in rank 5 and rank 6 models and analyze the supersymmetric parameter space where the light neutralinos have mainly singlino or MSSM character. The neutralino character, resonance effects of the new gauge bosons and, assuming mSUGRA-type RGEs, different selectron masses lead to significant differences between the MSSM and the extended models in neutralino production at an e^+e^- linear collider. Read More

**Authors:**R. -D. Heuer, D. J. Miller, F. Richard, P. M. Zerwas, J. A. Aguilar-Saavedra, J. Alcaraz, A. Ali, S. Ambrosanio, A. Andreazza, J. Andruszkow, B. Badelek, A. Ballestrero, T. Barklow, A. Bartl, M. Battaglia, T. Behnke, G. Belanger, D. Benson, M. Berggren, W. Bernreuther, M. Besancon, J. Biebel, O. Biebel, I. Bigi, J. J. van der Bij, T. Binoth, G. A. Blair, C. Blochinger, J. Blumlein, M. Boonekamp, E. Boos, G. Borissov, A. Brandenburg, J. -C. Brient, G. Bruni, K. Busser, P. Burrows, R. Casalbuoni, C. Castanier, P. Chankowski, A. Chekanov, R. Chierici, S. Y. Choi, P. Christova, P. Ciafaloni, D. Comelli, G. Conteras, M. Danilov, W. Da Silva, A. Deandrea, W. de Boer, S. De Curtis, S. J. De Jong, A. Denner, A. De Roeck, K. Desch, E. De Wolf, S. Dittmaier, V. Djordjadze, A. Djouadi, D. Dominici, M. Doncheski, M. T. Dova, V. Drollinger, H. Eberl, J. Erler, A. Eskreys, J. R. Espinosa, N. Evanson, E. Fernandez, J. Forshaw, H. Fraas, F. Franke, A. Freitas, F. Gangemi, P. Garcia-Abia, R. Gatto, P. Gay, T. Gehrmann, A. Gehrmann-De Ridder, U. Gensch, N. Ghodbane, I. F. Ginzburg, R. Godbole, S. Godfrey, G. Gounaris, M. Grazzini, E. Gross, B. Grzadkowski, J. Guasch, J. F. Gunion, K. Hagiwara, T. Han, K. Harder, R. Harlander, R. Hawkings, S. Heinemeyer, S. Hesselbach, C. A. Heusch, J. Hewett, G. Hiller, A. Hoang, W. Hollik, J. I. Illana, V. A. Ilyin, D. Indumathi, S. Ishihara, M. Jack, S. Jadach, F. Jegerlehner, M. Jezabek, G. Jikia, L. Jonsson, P. Jankowski, P. Jurkiewicz, A. Juste, A. Kagan, J. Kalinowski, M. Kalmykov, P. Kalyniak, B. Kamal, J. Kamoshita, S. Kanemura, F. Kapusta, S. Katsanevas, R. Keranen, V. Khoze, A. Kiiskinen, W. Kilian, M. Klasen, J. L. Kneur, B. A. Kniehl, M. Kobel, K. Kolodziej, M. Kramer, S. Kraml, M. Krawczyk, J. H. Kuhn, J. Kwiecinski, P. Laurelli, A. Leike, J. Letts, W. Lohmann, S. Lola, P. Lutz, P. Mattig, W. Majerotto, T. Mannel, M. Martinez, H. -U. Martyn, T. Mayer, B. Mele, M. Melles, W. Menges, G. Merino, N. Meyer, D. J. Miller, P. Minkowski, R. Miquel, K. Monig, G. Montagna, G. Moortgat-Pick, P. Mora de Freitas, G. Moreau, M. Moretti, S. Moretti, L. Motyka, G. Moultaka, M. Muhlleitner, U. Nauenberg, R. Nisius, H. Nowak, T. Ohl, R. Orava, J. Orloff, P. Osland, G. Pancheri, A. A. Pankov, C. Papadopoulos, N. Paver, D. Peralta, H. T. Phillips, F. Picinini, W. Placzek, M. Pohl, W. Porod, A. Pukhov, A. Raspereza, D. Reid, S. Riemann, T. Riemann, S. Rosati, M. Roth, S. Roth, C. Royon, R. Ruckl, E. Ruiz-Morales, M. Sachwitz, J. Schieck, H. -J. Schreiber, D. Schulte, M. Schumacher, R. D. Settles, M. Seymour, R. Shanidze, T. Sjostrand, M. Skrzypek, S. Soldner-Rembold, A. Sopczak, H. Spiesberger, M. Spira, H. Steiner, M. Stratmann, Y. Sumino, S. Tapprogge, V. Telnov, T. Teubner, A. Tonazzo, C. Troncon, O. Veretin, C. Verzegnassi, A. Vest, A. Vicini, H. Videau, W. Vogelsang, A. Vogt, H. Vogt, D. Wackeroth, A. Wagner, S. Wallon, G. Weiglein, S. Weinzierl, T. Wengler, N. Wermes, A. Werthenbach, G. Wilson, M. Winter, A. F. Zarnecki, B. Ziaja, J. Zochowski

**Category:**High Energy Physics - Phenomenology

The TESLA Technical Design Report Part III: Physics at an e+e- Linear Collider Read More

There are many models with non-universal soft SUSY breaking sfermion mass parameters at the grand unification scale. Even in the mSUGRA model scalar mass unification might occur at a scale closer to M_Planck, and renormalization effects would cause a mass splitting at M_GUT. We identify an experimentally measurable quantity Delta that correlates strongly with delta m^2 = m^2_{selectron_R}(M_GUT) - m^2_{selectron_L}(M_GUT), and which can be measured at electron-positron colliders provided both selectrons and the chargino are kinematically accessible. Read More

In extended supersymmetric models with additional singlet Higgs fields displaced vertices could be observed if the decay width of the next-to-lightest supersymmetric particle becomes very small due to a singlino dominated LSP. We study the supersymmetric parameter space where displaced vertices of the second lightest neutralino exist in the NMSSM and an E6 inspired model. For a mass difference between LSP and NLSP of more than 10 GeV the singlet vacuum expectation value has to be at least of the order of 100 TeV in order to obtain a lightest neutralino with a singlino component large enough for displaced vertices. Read More

We discuss associated neutralino production e^+ e^- --> \tilde{\chi}^0_1 \tilde{\chi}^0_2 with both beams polarized in the MSSM, NMSSM and an E_6 model. It is shown that neutralinos with a large singlino component can be produced at a high luminosity linear collider in a broad parameter range. Polarization effects in the extended models are compared over the whole parameter space where the lightest neutralino is mainly a singlino. Read More

We study the possibility to measure the masses of the selectrons in neutralino production at an e^+ e^- linear collider with polarized beams. The cross sections and polarization asymmetries of neutralinos with gaugino character strongly depend on the masses of the exchanged selectrons. If the usual GUT relations of the selectron masses in the MSSM are relaxed large effects are possible especially in the polarization asymmetries. Read More