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Search Results: 1 - 10 of 925 matches for " Nir Yosef "
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Lessons from BaBar and Belle measurements of D-Dbar mixing parameters
Nir, Yosef
High Energy Physics - Phenomenology , 2007, DOI: 10.1088/1126-6708/2007/05/102
Abstract: The BaBar and Belle experiments have recently presented evidence for D-Dbar mixing. We explain the following points: (i) The measurements imply width difference $y \sim 0.01$. In the limit of small CP violation, the CP-odd state is longer-lived; (ii) $y\sim0.01$ is consistent with the Standard Model. It suggests that SU(3) breaking from phase space effects is likely to play a major role; (iii) There is no evidence for either large mass splitting or CP violation. Consequently, there is no hint for new physics; (iv) The stronger bounds on the mass splitting and on CP violation imply that, if squarks are observed at the LHC, it is unlikely that they will be non-degenerate.
Probing new physics with flavor physics (and probing flavor physics with new physics)
Nir, Yosef
High Energy Physics - Phenomenology , 2007,
Abstract: This is a written version of a series of lectures aimed at graduate students and postdoctoral fellows in particle theory/string theory/particle experiment familiar with the basics of the Standard Model. We begin with an overview of flavor physics and its implications for new physics. We emphasize the "new physics flavor puzzle". Then, we give four specific examples of flavor measurements and the lessons that have been (or can be) drawn from them: (i) Charm physics: lessons for supersymmetry from the upper bound on $\Delta m_D$. (ii) Bottom physics: model independent lessons on the KM mechanism and on new physics in neutral B mixing from $S_{\psi K_S}$. (iii) Top physics and beyond: testing minimal flavor violation at the LHC. (iv) Neutrino physics: interpreting the data on neutrino masses and mixing within flavor models.
Introduction to leptogenesis
Nir, Yosef
High Energy Physics - Phenomenology , 2007,
Abstract: The discovery of neutrino masses makes leptogenesis a very attractive scenario for explaining the puzzle of the baryon asymmetry of the Universe. We present the basic ingredients of leptogenesis, explain the predictive power of this scenario (and its limitations), and describe recent theoretical developments.
New Physics Effects on CP Violation in $B$ Decays
Yosef Nir
Physics , 1993,
Abstract: We review new physics effects on CP violation in B decays. We describe the Standard Model predictions for the various types of CP asymmetries and discuss the theoretical cleanliness of these predictions. We point out the ingredients in the analysis that are most sensitive to new physics and deduce the type of new physics that is likely to modify the Standard Model predictions. Several explicit examples are discussed in detail. Finally, we explain how, if deviations from the Standard Model predictions are measured, we will be able to learn detailed features of the new physics involved. Plenary talk presented at the Workshop on B Physics at Hadron Accelerators, Snowmass, Colorado, June 21 - July 2, 1993.
Recent Developments in Theory of CP Violation
Yosef Nir
Physics , 1997,
Abstract: Four topics in theory of CP violation are reviewed. (a) CP violation in $B$ decays: We describe a new clean way of constraining the angle $\gamma$ of the unitarity triangle and how new CP violation in decay amplitudes can signal new physics. (b) CP violation in $K$ decays: We explain the special features of the decay $K_L\ra\pi^0\nu\bar\nu$ both as a measurement of Standard Model CP violating parameters and as a probe of new physics. (c) CP violation in $D$ decays: We describe the consequences of CP violation from new physics in $D-\bar D$ mixing. (d) CP violation in Supersymmetry: We explain how a combination of measurements of CP violating processes will give insight into the flavor and CP structure of supersymmetry.
CP Violation in B Decays
Yosef Nir
Physics , 1999,
Abstract: In the near future, we will have the first significant experimental measurements of CP violation in B decays. These measurements will easily test crucial questions such as whether the Standard Model Kobayashi-Maskawa phase plays a dominant role in CP violation or whether CP is an approximate symmetry in nature. We explain the different types of CP violation in B decays, and the usefulness of measuring them. We use the same formalism to describe the epsilon and epsilon(prime) parameters of the neutral K system and to explain the terms direct and indirect CP violation. We present the Standard Model predictions for the various asymmetries. We argue that certain CP asymmetries in B decays are subject to a very clean theoretical interpretation in terms of fundamental Lagrangian parameters. Within the Standard Model, these asymmetries will provide very accurate measurements of the CKM parameters. In case that deviations from the Standard Model predictions will be found, there is enough information to understand the nature of New Physics that is required to explain them. We demonstrate this statement by analyzing the impact of various Supersymmetric flavor models on CP violation.
Gauge Unification, Yukawa Hierarchy and the $μ$ Problem
Yosef Nir
Physics , 1995, DOI: 10.1016/0370-2693(95)00619-V
Abstract: The hierarchy in the Yukawa couplings may be the result of a gauged horizontal $U(1)_H$ symmetry. If the mixed anomalies of the Standard Model gauge group with $U(1)_H$ are cancelled by a Green-Schwarz mechanism, a relation between the gauge couplings, the Yukawa couplings and the $\mu$-term arises. Assuming that at a high energy scale $g_3^2=g_2^2={5\over3}g_1^2$ and $(m_e m_\mu m_\tau)/(m_d m_s m_b)\sim \lambda$ (where $\lambda$ is of the order of the Cabibbo angle), the $U(1)_H$ symmetry solves the $\mu$-problem with $\mu\sim\lambda m_{3/2}$.
On Supersymmetric CP Violation
Yosef Nir
Physics , 1996,
Abstract: We discuss the discovery potential for New Physics of various measurements of CP violation. If nature is supersymmetric, then the flavor problem is even more mysterious than in the standard model. We show how we can learn about the mechanism that solves the supersymmetric flavor problem from measurements of mixing and CP violation in $K$, $D$ and $B$ decays. (Invited talk given at the Workshop on K Physics, Orsay, France, May 30 - June 4, 1996.)
Flavor Physics and CP Violation
Yosef Nir
Physics , 1998,
Abstract: This is a written version of a series of three lectures aimed at graduate students in the field of experimental high energy physics. The emphasis is on physics that is relevant to $B$-factories. The main topics covered are: (i) The flavor sector of the Standard Model; (ii) Determination of the mixing parameters; (iii) CP violation in meson decays (a model independent description); (iv) CP violation in the Standard Model; (v) CP violation as a probe of new physics.
Naturally Small $x_s$?
Yosef Nir
Physics , 1994, DOI: 10.1016/0370-2693(94)91533-4
Abstract: Within the Standard Model, $x_s$ (the mixing parameter in the $B_s-\bar B_s$ system) is constrained to the range $7 \leq x_s\leq 40$. We point out that if New Physics contributes significantly to $x_d$ (the mixing parameter in the $B_d-\bar B_d$ system), then $2 \leq x_s\leq 7$ is possible without any fine-tuned cancellations between the Standard Model and the New Physics contributions.
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