A. Masiero

University of Padova, Padua, Veneto, Italy

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Publications (239)843.54 Total impact

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    ABSTRACT: With the discovery of the Higgs boson the Standard Model has become a complete and comprehensive theory, which has been verified with unparalleled precision and in principle might be valid at all scales. However, several reasons remain why we firmly believe that there should be physics beyond the Standard Model. Experiments such as the LHC, new $B$ factories, and earth- and space-based astro-particle experiments provide us with unique opportunities to discover a coherent framework for many of the long-standing puzzles of our field. Here we explore several significant interconnections between the physics of the Higgs boson, the physics of flavour, and the experimental clues we have about dark matter.
    Preview · Article · Jul 2015 · European Physical Journal Plus
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    ABSTRACT: Motivated by the null results of LHC searches, which together with the Higgs mass, severely constrain minimal supersymmetric extensions of the standard model, we adopt a model-independent approach to study charged slepton flavor. We examine a number of simplified models, with different subsets of sleptons, electroweak gauginos, and Higgsinos, and derive the allowed slepton flavor dependence in the region probed by current LHC searches, and in the region relevant for the 14 TeV LHC. We then study the impact of the allowed flavor dependence on lepton plus missing energy searches. In some cases, flavor dependence significantly modifies the reach of the searches. These effects may be even larger at the next LHC run, since for the higher masses probed at 14 TeV, larger flavor mixings and relative mass splittings are compatible with low-energy constraints. Retaining the full lepton flavor information can increase the sensitivity of the searches.
    Preview · Article · Feb 2015 · Journal of High Energy Physics
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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.
    Preview · Article · Mar 2013 · New Journal of Physics
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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.
    Full-text · Article · Nov 2012 · Journal of High Energy Physics
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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.
    Preview · Article · May 2012 · Journal of High Energy Physics
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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 →μμ and μ→eγ. 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.
    Full-text · Article · Feb 2012 · European Physical Journal C
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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.
    Full-text · Conference Paper · Nov 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.
    No preview · Chapter · Dec 2010
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    ABSTRACT: In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor.In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved, apart from their masses and quantum numbers, 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. In the past, observations of CP violation were confined to neutral $K$ mesons, but since the early 1990s, 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 is the result of the work of the physicists attending the $5^{th}$ CKM workshop, hosted by the University of Rome "La Sapienza", September 9-13, 2008. It 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 which has greatly improved in the past decade.
    Full-text · Article · Sep 2010 · Physics Reports
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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.
    Full-text · Article · May 2010 · Nuclear Physics B
  • A. Masiero
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    ABSTRACT: After more than four decades of impressive and frustrating theoretical and experimental efforts to reveal signals of the presence of TeV new physics through its effects in CP-conserving and CP-violating flavour-changing neutralcurrent 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. In this talk I focus on 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. © Società Italiana di Fisica / INFN - Laboratori Nazionali di Frascati.
    No preview · Article · Jan 2010
  • O. Vives · J.J. Pérez · L. Calibbi · A. Masiero · J.-H. Park · W. Porod
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    ABSTRACT: Supersymmetry is one of the best options among the possible extensions of the SM that can be found at the LHC. However, most of the phenomenological analysis have been done neglecting flavour structures. In this paper, we show that a realistic flavour symmetry can simultaneously explain the flavour structures in the Yukawa matrices and solve the so-called SUSY flavour problem without ad hoc modifications of the SUSY model. Furthermore, departures from the SM expectations in these models can be used to discriminate among different possibilities. 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 ∈K. Thus, these flavoured MSSM realizations are phenomenologically sensitive to the experimental searches in the realm of flavour and CP violation physics.
    No preview · Article · Jan 2010 · Acta Physica Polonica B, Proceedings Supplement
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    R. Catena · N. Fornengo · M. Pato · L Pieri · A. Masiero
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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
    Full-text · Article · Dec 2009 · Physical review D: Particles and fields
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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.
    Full-text · Article · Nov 2009 · Physics Letters B
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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.
    Full-text · Conference Paper · Sep 2009
  • A. Masiero
    [Show abstract] [Hide abstract]
    ABSTRACT: After more than four decades of impressive and frustrating theoretical and experimental efforts to reveal signals of the presence of TeV new physics through its effects in CP-conserving and CP-violating flavour-changing neutralcurrent 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. In this talk I focus on 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.
    No preview · Article · Sep 2009
  • Source
    [Show abstract] [Hide abstract]
    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
    Full-text · Article · Jul 2009
  • 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.
    No preview · Article · Jun 2009 · Journal of Physics Conference Series
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    Antonio Masiero
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    ABSTRACT: After more than four decades of impressive and frustrating theoretical and 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.
    Preview · Article · Jan 2009 · Progress of Theoretical Physics Supplement
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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.
    Full-text · Article · Aug 2008 · European Physical Journal C

Publication Stats

9k Citations
843.54 Total Impact Points

Institutions

  • 1979-2013
    • University of Padova
      • Department of Physics and Astronomy "Galileo Galilei"
      Padua, Veneto, Italy
  • 1983-2012
    • INFN - Istituto Nazionale di Fisica Nucleare
      Frascati, Latium, Italy
  • 2010
    • Washington University in St. Louis
      San Luis, Missouri, United States
  • 2009
    • It-Robotics
      Vicenza, Veneto, Italy
  • 2007
    • Pierre and Marie Curie University - Paris 6
      • Institut d'astrophysique de Paris
      Lutetia Parisorum, Île-de-France, France
  • 1986-2002
    • Scuola Internazionale Superiore di Studi Avanzati di Trieste
      Trst, Friuli Venezia Giulia, Italy
  • 2001
    • University of Valencia
      Valenza, Valencia, Spain
  • 1995-1998
    • Università degli Studi di Perugia
      • Department of Physics
      Perugia, Umbria, Italy
  • 1983-1993
    • CERN
      • Physics Department (PH)
      Genève, Geneva, Switzerland
  • 1992
    • Sapienza University of Rome
      • Department of Physics
      Roma, Latium, Italy
  • 1991
    • University of Cambridge
      • Institute of Astronomy
      Cambridge, England, United Kingdom
  • 1989
    • University of Helsinki
      • Department of Physics
      Helsinki, Southern Finland Province, Finland
  • 1986-1988
    • CUNY Graduate Center
      New York, New York, United States
  • 1984
    • Tohoku University
      • Department of Physics
      Miyagi, Japan
    • Ecole Normale Supérieure de Paris
      • Laboratoire de Physique Théorique
      Lutetia Parisorum, Île-de-France, France
  • 1982-1983
    • Max Planck Institute of Physics
      München, Bavaria, Germany
    • University of Pennsylvania
      Filadelfia, Pennsylvania, United States
    • Ludwig-Maximilians-University of Munich
      München, Bavaria, Germany
  • 1980-1982
    • Max Planck Institute for Astrophysics
      Arching, Bavaria, Germany
    • University of Geneva
      • Department of Theoretical Physics
      Genève, Geneva, Switzerland
    • Carnegie Mellon University
      Pittsburgh, Pennsylvania, United States