A. Masiero

University of Padova, Padua, Veneto, Italy

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Publications (224)652.68 Total impact

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    P Di Bari, A Masiero, R Mohapatra
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    ABSTRACT: The origin of matter in the Universe is a fascinating cosmological puzzle that has triggered a formidable intellectual enterprise, started in 1967 with the prescient paper by Andrej Sakharov (1967 Pisma Zh. Eksp. Teor. Fiz. 5 32; 1967 JETP Lett. 52 4; 1991 Sov. Phys.—Usp. 34 392; 1991 Usp. Fiz. Nauk 161 61) aimed at relating a cosmological observation to the fundamental laws of physics, the goal of baryogenesis. A successful model of baryogenesis should ultimately identify the required source of charge parity violation and the origin of the cosmological matter–antimatter asymmetry. This focus issue is not only a review of the main ideas that have been proposed in baryogenesis but should also bear witness to the great vitality of the field and to show how future experimental results could bring a breakthrough in baryogenesis during the coming years. For this reason we selected, out of the multitude of proposed baryogenesis models, those that will more likely experience a significant experimental test during the coming years.
    New Journal of Physics 03/2013; 15(3):035030. · 4.06 Impact Factor
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    ABSTRACT: The presence of new matter fields charged under the Standard Model gauge group at intermediate scales below the Grand Unification scale modifies the renormalization group evolution of the gauge couplings. This can in turn significantly change the running of the Minimal Supersymmetric Standard Model parameters, in particular the gaugino and the scalar masses. In the absence of new large Yukawa couplings we can parameterise all the intermediate scale models in terms of only two parameters controlling the size of the unified gauge coupling. As a consequence of the modified running, the low energy spectrum can be strongly affected with interesting phenomenological consequences. In particular, we show that scalar over gaugino mass ratios tend to increase and the regions of the parameter space with neutralino Dark Matter compatible with cosmological observations get drastically modified. Moreover, we discuss some observables that can be used to test the intermediate scale physics at the LHC in a wide class of models.
    Journal of High Energy Physics 05/2012; 2012(8). · 5.62 Impact Factor
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    ABSTRACT: The current 7 TeV run of the LHC experiment shall be able to probe gluino and squark masses up to values larger than 1 TeV. Assuming that hints for SUSY are found in the jets plus missing energy channel by the end of a 5 fb$^{-1}$ run, we explore the flavour constraints on three models with a CMSSM-like spectrum: the CMSSM itself, a Seesaw extension of the CMSSM, and Flavoured CMSSM. In particular, we focus on decays that might have been measured by the time the run is concluded, such as $B_s\to\mu\mu$ and $\mu\to e\gamma$. We also analyse constraints imposed by neutral meson bounds and electric dipole moments. The interplay between collider and flavour experiments is explored through the use of three benchmark scenarios, finding the flavour feedback useful in order to determine the model parameters and to test the consistency of the different models.
    European Physical Journal C 02/2012; 72(2). · 5.25 Impact Factor
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    ABSTRACT: We report on the status of supersymmetric seesaw models in the light of recent experimental results on μ → e + γ, θ 13 and the light Higgs mass at the LHC. SO(10)-like relations are assumed for neutrino Dirac Yukawa couplings and two cases of mixing, one large, PMNS-like, and another small, CKM-like, are considered. It is shown that for the large mixing case, only a small range of parameter space with moderate tan β is still allowed. This remaining region can be ruled out by an order of magnitude improvement in the current limit on BR(μ → e + γ). We also explore a model with non-universal Higgs mass boundary conditions at the high scale. It is shown that the renormalization group induced flavor violating slepton mass terms are highly sensitive to the Higgs boundary conditions. Depending on the choice of the parameters, they can either lead to strong enhancements or cancellations within the flavor violating terms. Such cancellations might relax the severe constraints imposed by lepton flavor violation compared to mSUGRA. Nevertheless for a large region of parameter space the predicted rates lie within the reach of future experiments once the light Higgs mass constraint is imposed. We also update the potential of the ongoing and future experimental searches for lepton flavor violation in constraining the supersymmetric parameter space.
    Journal of High Energy Physics 01/2012; 2012(11). · 5.62 Impact Factor
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    Conference Paper: SUSY Flavour at LHC7
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    ABSTRACT: The current 7 TeV run of the LHC experiment shall be able to probe gluino and squark masses up to values of about 1 TeV. Assuming that hints for SUSY are found by the end of a 2 fb−1 run, we explore the flavour constraints on the parameter space of the CMSSM, with and without massive neutrinos. In particular, we focus on decays that might have been measured by the time the run is concluded, such as Bs→μμ and μ→eγ. We also briefly show the impact such a collider--flavour interplay would have on a Flavoured CMSSM.
    2011 Europhysics Conference on High Energy Physics (EPS-HEP 2011); 11/2011
  • Antonio Masiero
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    ABSTRACT: This is an elementary introduction to some issues of Dark Matter, particularly devoted to readers who are not familiar with the particle physics background needed to address this chapter of astroparticle physics.
    12/2010: pages 273-293;
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    ABSTRACT: 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 an 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 μ→eγ and τ→μγ, electric dipole moments, de and dn and kaon CP violating processes as ϵK. We also show that without further modifications, it is unlikely for these models to solve the ΦBs anomaly at low-moderate . Thus, these flavoured MSSM realizations are phenomenologically sensitive to the experimental searches in the realm of flavor and CP violation physics.
    Nuclear Physics B 01/2010; · 4.33 Impact Factor
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    ABSTRACT: Alternative cosmologies, based on extensions of General Relativity, predict modified thermal histories in the Early Universe during the pre Big Bang Nucleosynthesis (BBN) era, epoch which is not directly constrained by cosmological observations. When the expansion rate is enhanced with respect to the standard case, thermal relics typically decouple with larger relic abundances. The correct value of the relic abundance is therefore obtained for larger annihilation cross--sections, as compared to standard cosmology. A direct consequence is that indirect detection rates are enhanced. Extending previous analyses of ours, we derive updated astrophysical bounds on the dark matter annihilation cross sections and use them to constrain alternative cosmologies in the pre--BBN era. We also determine the characteristics of these alternative cosmologies in order to provide the correct value of relic abundance for a thermal relic for the (large) annihilation cross--section required to explain the PAMELA results on the positron fraction, therefore providing a "cosmological boost" solution to the dark matter interpretation of the PAMELA data. Comment: 19 pages, 27 figures, matches published version
    Physical review D: Particles and fields 12/2009;
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    ABSTRACT: In order to satisfy current FCNC and CP violation bounds, SUSY flavour structures cannot be generic. An interesting solution to these SUSY Flavour and CP Problems lies on the use of an SU(3) family symmetry which spontaneously breaks CP symmetry. Typical observables of such a model are electric dipole moments and LFV processes. In addition, these models can give contributions to CP violation in neutral meson mixing. We show how the latter can be used to restrict the allowed SUSY parameter space, and induce correlations between LFV and EDM predictions.
    2009 Europhysics Conference on High Energy Physics (EPS-HEP 2009); 09/2009
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    ABSTRACT: One of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor and measurements and theoretical interpretations of their results have advanced tremendously: apart from masses and quantum numbers of flavor particles, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. Till early 1990s observations of CP violation were confined to neutral $K$ mesons, but since then a large number of CP-violating processes have been studied in detail in neutral $B$ mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of $K, D$, and $B$ mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of the status of quark flavor physics is timely. This report summarizes the results of the current generation of experiments that is about to be completed and it confronts these results with the theoretical understanding of the field. Comment: Report of the CKM workshop, Rome 9-13th Sep. 2008, 340 pages, 106 postscript figures, submitted to Phys. Repts
  • Antonio Masiero
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    ABSTRACT: Given that nucleosynthesis (BBN) provides the oldest available information we have on the evolution of the Universe, it is worthwhile exploring possible deviations from the standard Big Bang cosmology based on General Relativity in pre-BBN epochs. Non-GR pre-BBN cosmologies affect the evolution of the WIMP DM component, in particular determining relevant shifts on its freeze-out temperature. The impact of this new 'degree of freedom' in the discussion of naturalness of WIMPs in playing the role of DM is presented in the context of Scalr Tensor (ST) theories of gravity.
    Journal of Physics Conference Series 06/2009; 171(1):012018.
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    S. Khalil, A. Masiero, H. Murayama
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    ABSTRACT: The difference between the CP asymmetries of the B0→K+π− and B+→K+π0 decays has been recently confirmed with an evidence larger than 5σ's. We discuss it as a possible signal of new physics associated with new (large) CP violation in the electroweak penguin contributions. We propose a supersymmetry breaking scheme where such new sources of CP violation occur in the flavor non-universal trilinear scalar couplings.
    Physics Letters B 01/2009; · 4.57 Impact Factor
  • Antonio Masiero
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    ABSTRACT: After more than four decades of impressive and frustrating theoreticaland experimental efforts to reveal signals of the presence of TeV new physics through its effects in CP conserving and CP violating flavour changing neutral current processes, the main response seems to lie in an effective flavour blindness of the new physics at the electroweak scale (Minimal Flavour Violation). This perspective keeps still open the door for main surprises in the sector of lepton flavor violation. Here we explore, together with other participants in the YKIS symposium at the Yukawa Institute, an alternative road where both the flavour puzzle within the Standard Model (i.e., a rationale for the smallness of Yukawa couplings and fermion mixings) and the flavour problem of TeV new physics are simultaneously tackled in a Supersymmetric extension of the Standard Model where the flavour structure is dictated by a (spontaneously broken) flavour or horizontal symmetry. I will discuss the main relevant implications of such class of models for both the leptonic and hadronic rare flavour changing processes.
    Progress of Theoretical Physics Supplement 01/2009; 180:48-60. · 1.25 Impact Factor
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    ABSTRACT: This chapter of the report of the ``Flavor in the era of the LHC'' Workshop discusses the theoretical, phenomenological and experimental issues related to flavor phenomena in the charged lepton sector and in flavor conserving CP-violating processes. We review the current experimental limits and the main theoretical models for the flavor structure of fundamental particles. We analyze the phenomenological consequences of the available data, setting constraints on explicit models beyond the standard model, presenting benchmarks for the discovery potential of forthcoming measurements both at the LHC and at low energy, and exploring options for possible future experiments.
    European Physical Journal C 08/2008; · 5.25 Impact Factor
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    A. Masiero, P. Paradisi, R. Petronzio
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    ABSTRACT: High precision electroweak tests, such as deviations from the Standard Model expectations of the Lepton Flavor Universality breaking in K->lnu (with l= e or mu), represent a powerful tool to test the Standard Model and, hence, to constrain or obtain indirect hints of New Physics beyond it. We explore such a possibility within Supersymmetric theories. Interestingly enough, a process that in itself does not need lepton flavor violation to occur, i.e. the violation of mu-e non-universality in K_l2, proves to be quite effective in constraining not only relevant regions of SUSY models where lepton flavor is conserved, but even those where specific lepton flavor violating contributions arise. Indeed, a comparison with analogous bounds coming from tau lepton flavor violating decays shows the relevance of the measurement of R_K to probe Lepton Flavor Violation in SUSY. We outline the role and the interplay of the direct New Physics searches at the LHC with the indirect searches performed by LFU tests.
    Journal of High Energy Physics 08/2008; · 5.62 Impact Factor
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    ABSTRACT: We determine under what conditions Scalar Tensor cosmologies predict an expansion rate which is reduced as compared to the standard General Relativity case. We show that ST theories with a single matter sector typically predict an enchanced Hubble rate in the past, as a consequence of the requirement of an attractive fixed point towards General Relativity at late times. Instead, when additional matter sectors with different conformal factors are added, the late time convergence to General Relativity is mantained and at the same time a reduced expansion rate in the past can be driven. For suitable choices of the parameters which govern the scalar field evolution, a sizeable reduction (up to about 2 orders of magnitude) of the Hubble rate prior to Big Bag Nucleosynthesis can be obtained. We then discuss the impact of these cosmological models on the relic abundance of dark matter is minimal Supergravity models: we show that the cosmologically allowed regions in parameter space are significantly enlarged, implying a change in the potential reach of LHC on the neutralino phenomenology.
    Journal of High Energy Physics 01/2008; 80. · 5.62 Impact Factor
  • Antonio Masiero, Oscar Vives
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    ABSTRACT: Although direct searches of supersymmetry (SUSY) constitute the only way we have to clearly verify the existence of a low-energy SUSY extension of the standard model, yet, in particular in our pre-LHC era, it is of utmost importance to study any possible signal where SUSY manifests itself indirectly in discrepancies with the SM expectations in rare processes. In this talk we’ll consider a wide range of flavor changing neutral current and/or CP violating phenomena where, indeed, SUSY contributions are comparable to the SM ones. Such analysis provides stringent constraints on different SUSY model parameter spaces and, at the same time, it individuates possible windows for SUSY signals in spite of all the existing constraints. Our attention will focus in particular on the CP violating processes which are the most sensitive place for SUSY effects in the vast class of rare phenomena of the SM
    01/2008: pages 93-105;
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    ABSTRACT: This Conference is the fifth of a series of Workshops on High Energy Gamma- ray Experiments, following the Conferences held in Perugia 2003, Bari 2004, Cividale del Friuli 2005, Elba Island 2006. This year the focus was on the use of gamma-ray to study the Dark Matter component of the Universe, the origin and propagation of Cosmic Rays, Extra Large Spatial Dimensions and Tests of Lorentz Invariance.
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    S. Khalil, A. Masiero
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    ABSTRACT: We propose a scheme where the three relevant physics scales related to the supersymmetry, electroweak, and baryon minus lepton (B−L) breakings are linked together and occur at the TeV scale. The phenomenological implications in the Higgs and leptonic sectors are discussed.
    Physics Letters B 01/2008; · 4.57 Impact Factor
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    A. Masiero, S. K. Vempati, O. Vives
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    ABSTRACT: In spite of the enormous success of the Standard Model (SM), we have strong reasons to expect the presence of new physics beyond the SM at higher energies. The idea of the Grand Unification of all the known interactions in nature is perhaps the main reason behind these expectations. Low-energy Supersymmetry is closely linked with grand unification as a solution of the hierarchy problem associated with the ratio M_GUT / M_Z. In these lectures we will provide a general overview of Grand Unification and Supersymmetry with special emphasis on their phenomenological consequences at low energies. We will analyse the flavour and CP problems of Supersymmetry and try to identify in these associated low-energy observables possible indications of the existence of a Grand Unified theory at high energies.

Publication Stats

6k Citations
652.68 Total Impact Points


  • 1979–2013
    • University of Padova
      Padua, Veneto, Italy
  • 2008
    • Ain Shams University
      • Faculty of Science
      Al Qāhirah, Al Qāhirah, Egypt
  • 1984–2008
    • INFN - Istituto Nazionale di Fisica Nucleare
      Frascati, Latium, Italy
    • Tohoku University
      • Department of Physics
      Sendai, Kagoshima-ken, Japan
  • 2007
    • Pierre and Marie Curie University - Paris 6
      • Institut d'astrophysique de Paris
      Lutetia Parisorum, Île-de-France, France
  • 2004
    • Università Degli Studi Roma Tre
      • Department of Mathematics and Physics
      Roma, Latium, Italy
  • 2002–2003
    • University of Oxford
      • Department of Physics
      Oxford, ENG, United Kingdom
  • 1997–2000
    • Scuola Internazionale Superiore di Studi Avanzati di Trieste
      Trst, Friuli Venezia Giulia, Italy
  • 1999
    • University of Valencia
      • Theoretical physics
      Valencia, Valencia, Spain
  • 1989–1997
    • Università degli Studi di Perugia
      • Department of Physics
      Perugia, Umbria, Italy
    • University of Helsinki
      • Department of Physics
      Helsinki, Southern Finland Province, Finland
  • 1992
    • University of Hawaiʻi at Mānoa
      • Department of Physics and Astronomy
      Honolulu, HI, United States
  • 1990
    • Instituto de Física Corpuscular
      • Department of Theoretical Physics
      Paterna, Valencia, Spain
  • 1981–1990
    • CERN
      • Physics Department (PH)
      Genève, Geneva, Switzerland
  • 1980–1990
    • University of Geneva
      • Department of Theoretical Physics
      Genève, GE, Switzerland
  • 1987–1988
    • CUNY Graduate Center
      New York City, New York, United States
    • Carnegie Mellon University
      • Department of Physics
      Pittsburgh, Pennsylvania, United States
  • 1986
    • New York University
      • Department of Physics
      New York City, NY, United States
  • 1982
    • Ludwig-Maximilians-University of Munich
      München, Bavaria, Germany
  • 1981–1982
    • Max Planck Institute for Astrophysics
      Arching, Bavaria, Germany