Papers by Lorenzo Mannelli
Physical review, Jun 9, 2005
We present a complete quantum mechanical description of a flat FRW universe with equation of stat... more We present a complete quantum mechanical description of a flat FRW universe with equation of state p = ρ. We find a detailed correspondence with our heuristic picture of such a universe as a dense black hole fluid. Features of the geometry are derived from purely quantum input.
Preprint typeset in JHEP style.- PAPER VERSION hep-th/0209113
dS/CFT gives a perturbatively gauge invariant definition of particle masses in de Sitter (dS) spa... more dS/CFT gives a perturbatively gauge invariant definition of particle masses in de Sitter (dS) space. We show, in a toy model in which the graviton is replaced with a minimally coupled massless scalar field, that loop corrections to these masses are infrared (IR) divergent. We argue that this implies anomalous dependence of masses on the cosmological constant, in a true theory of quantum gravity. This is in accord with the hypothesis of Cosmological SUSY Breaking (CSB).
Physical review, Dec 1, 2009
We consider a supersymmetric matrix quantum mechanics. This is obtained by adding Myers and mass ... more We consider a supersymmetric matrix quantum mechanics. This is obtained by adding Myers and mass terms to the dimensional reduction of 4d N = 1 super Yang-Mills theory to one dimension. Using this model we construct 4d N = 1 super Yang-Mills theory in the planar limit by using the Eguchi-Kawai equivalence. This regularization turns out to be free from the sign problem at the regularized level. The same matrix quantum mechanics is also used to provide a nonperturbative formulation of 4d N = 1 super Yang-Mills theory on a noncommutative space.
We study the planar-flow distributions of narrow, highly boosted, massive QCD jets. Using the fac... more We study the planar-flow distributions of narrow, highly boosted, massive QCD jets. Using the factorization properties of QCD in the collinear limit, we compute the planar-flow jet function from the one-to-three splitting function at tree-level. We derive the leading-log behavior of the jet function analytically. We also compare our semi-analytic jet function with parton-shower predictions using various generators.
Physics Letters B, 2010
A simple formalism to describe flavor and CP violation in a model independent way is provided. Ou... more A simple formalism to describe flavor and CP violation in a model independent way is provided. Our method is particularly useful to derive robust bounds on models with arbitrary mechanisms of alignment. Known constraints on flavor violation in the K and D systems are reproduced in a straightforward and covariant manner. Assumptions-free limits, based on top flavor violation at the LHC, are then obtained. In the absence of signal, with 100 fb −1 of data, the LHC will exclude weakly coupled (strongly coupled) new physics up to a scale of 0.6 TeV (7.6 TeV), while at present no general constraint can be set related to ∆t = 1 processes. ∆F = 2 contributions will be constrained via same-sign tops signal, with a model independent exclusion region of 0.08 TeV (1.0 TeV). However, in this case, stronger bounds are found from the study of CP violation in D − D mixing with a scale of 0.57 TeV (7.2 TeV). We also apply our analysis to supersymmetric and warped extra dimension models.
Journal of High Energy Physics, 2010
A simple covariant formalism to describe flavor and CP violation in the left-handed quark sector ... more A simple covariant formalism to describe flavor and CP violation in the left-handed quark sector in a model independent way is provided. The introduction of a covariant basis, which makes the standard model approximate symmetry structure manifest, leads to a physical and transparent picture of flavor conversion processes. Our method is particularly useful to derive robust bounds on models with arbitrary mechanisms of alignment. Known constraints on flavor violation in the K and D systems are reproduced in a straightforward manner. Assumptions-free limits, based on top flavor violation at the LHC, are then obtained. In the absence of signal, with 100 fb−1 of data, the LHC will exclude weakly coupled (strongly coupled) new physics up to a scale of 0.6 TeV (7.6 TeV), while at present no general constraint can be set related to Δt= 1 processes. LHC data will constrain ΔF= 2 contributions via same-sign tops signal, with a model independent exclusion region of 0.08 TeV (1.0 TeV). However, in this case, stronger bounds are found from the study of CP violation in $ D - \overline D $ mixing with a scale of 0.57 TeV (7.2 TeV). In addition, we apply our analysis to models of supersymmetry and warped extra dimension. The minimal flavor violation framework is also discussed, where the formalism allows to distinguish between the linear and generic non-linear limits within this class of models.
We consider a supersymmetric matrix quantum mechanics. This is obtained by adding Myers and mass ... more We consider a supersymmetric matrix quantum mechanics. This is obtained by adding Myers and mass terms to the dimensional reduction of 4d N = 1 super Yang-Mills theory to one dimension. Using this model we construct 4d N = 1 super Yang-Mills theory in the planar limit by using the Eguchi-Kawai equivalence. This regularization turns out to be free from the sign problem at the regularized level. The same matrix quantum mechanics is also used to provide a nonperturbative formulation of 4d N = 1 super Yang-Mills theory on a noncommutative space.
Journal of High Energy Physics, 2009
Using the Eguchi-Kawai equivalence, we provide regularizations of supersymmetric quiver and Chern... more Using the Eguchi-Kawai equivalence, we provide regularizations of supersymmetric quiver and Chern-Simons gauge theories which leave the supersymmetries unbroken. This allow us to study many interesting theories on a computer. As examples we construct large-N reduced models of supersymmetric QCD with flavor and the ABJM model of multiple M2 branes.
Journal of High Energy Physics, 2007
I put metastable supersymmetry breaking in a cosmological context. I argue that under reasonable ... more I put metastable supersymmetry breaking in a cosmological context. I argue that under reasonable assumptions, the cooling down early Universe favors metastable SUSY-breaking vacua over the stable supersymmetric vacua. To illustrate the general argument, I analyze the early-Universe history of the Intriligator-Seiberg-Shih model.
I put metastable supersymmetry breaking in a cosmological context. I argue that under reasonable ... more I put metastable supersymmetry breaking in a cosmological context. I argue that under reasonable assumptions, the cooling down early Universe favors metastable SUSY-breaking vacua over the stable supersymmetric vacua. To illustrate the general argument, I analyze the early-Universe history of the Intriligator-Seiberg-Shih model.
We present a complete quantum mechanical description of a flat FRW universe with equation of stat... more We present a complete quantum mechanical description of a flat FRW universe with equation of state p = ρ. We find a detailed correspondence with our heuristic picture of such a universe as a dense black hole fluid. Features of the geometry are derived from purely quantum input.
dS/CFT gives a perturbatively gauge invariant definition of particle masses in de Sitter (dS) spa... more dS/CFT gives a perturbatively gauge invariant definition of particle masses in de Sitter (dS) space. We show, in a toy model in which the graviton is replaced with a minimally coupled massless scalar field, that loop corrections to these masses are infrared (IR) divergent. We argue that this implies anomalous dependence of masses on the cosmological constant, in a true theory of quantum gravity. This is in accord with the hypothesis of Cosmological SUSY Breaking (CSB).
We analyze the renormalization properties of quantum field theories in de Sitter space and show t... more We analyze the renormalization properties of quantum field theories in de Sitter space and show that only two of the maximally invariant vacuum states of free fields lead to consistent perturbation expansions. One is the Euclidean vacuum and the other can be viewed as an analytic continuation of Euclidean functional integrals on RP d . The corresponding Lorentzian manifold is the future half of global de Sitter space with boundary conditions on fields at the origin of time. We argue that the perturbation series in this case has divergences at the origin which render the future evolution of the system indeterminate, without a better understanding of high energy physics.
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Papers by Lorenzo Mannelli