Sonia El Hedri - Editor

Sonia El Hedri
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Name
Sonia El Hedri
Affiliation
Editor
City
Rio Rico
Country
United States

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High Energy Physics - Phenomenology (15)
 
High Energy Physics - Experiment (2)
 
Astrophysics of Galaxies (1)

Publications Authored By Sonia El Hedri

New scalars from an extended Higgs sector could have weak scale masses and still have escaped detection. In a Type I Two Higgs Doublet Model, for instance, even the charged Higgs can be lighter than the top quark. Because electroweak production of these scalars is modest, the greatest opportunity for their detection might come from rare top decays. Read More

We perform a general study of the relic density and LHC constraints on simplified models where the dark matter coannihilates with a strongly interacting particle X. In these models, the dark matter depletion is driven by the self-annihilation of X to pairs of quarks and gluons through the strong interaction. The phenomenology of these scenarios therefore only depends on the dark matter mass and the mass splitting between dark matter and X as well as the quantum numbers of X. Read More

We present analytical formulae for the Sommerfeld corrections to the annihilation of massive color particles into quarks and gluons through the strong interaction. These corrections are essential to accurately compute the dark matter relic density for coannihilation with colored partners. Our formulae allow to compute the Sommerfeld effect, not only for the lowest term in the angular momentum expansion of the amplitude, but for all orders in the partial wave expansion. Read More

Simplified models of the dark matter (co)annihilation mechanism predict striking new collider signatures untested by current searches. These models, which were codified in the coannihilation codex, provide the basis for a dark matter (DM) discovery program at the Large Hadron Collider (LHC) driven by the measured DM relic density. In this work, we study an exemplary model featuring $s$-channel DM coannihilation through a scalar diquark mediator as a representative case study of scenarios with strongly interacting coannihilation partners. Read More

Simplified Models are a useful way to characterize new physics scenarios for the LHC. Particle decays are often represented using non-renormalizable operators that involve the minimal number of fields required by symmetries. Generalizing to a wider class of decay operators allows one to model a variety of final states. Read More

We present a general classification of simplified models that lead to dark matter (DM) coannihilation processes of the form DM + X $\rightarrow$ SM$_1$ + SM$_2$, where X is a coannihilation partner for the DM particle and SM$_1$, SM$_2$ are Standard Model fields. Our classification also encompasses regular DM pair annihilation scenarios if DM and X are identical. Each coannhilation scenario motivates the introduction of a mediating particle M that can either belong to the Standard Model or be a new field, whereby the resulting interactions between the dark sector and the Standard Model are realized as tree-level and dimension-four couplings. Read More

Dark matter that was once in thermal equilibrium with the Standard Model is generally prohibited from obtaining all of its mass from the electroweak or QCD phase transitions. This implies a new scale of physics and mediator particles needed to facilitate dark matter annihilations. In this work, we consider scenarios where thermal dark matter annihilates via scalar mediators that are colored and/or electrically charged. Read More

Dark matter that was once in thermal equilibrium with the Standard Model is generally prohibited from obtaining all of its mass from the electroweak phase transition. This implies a new scale of physics and mediator particles to facilitate dark matter annihilation. In this work, we focus on dark matter that annihilates through a generic gauge boson portal. Read More

We place perturbative unitarity constraints on both the dimensionful and dimensionless parameters in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) Higgs Sector. These constraints, plus the requirement that the singlino and/or Higgsino constitutes at least part of the observed dark matter relic abundance, generate upper bounds on the Higgs, neutralino and chargino mass spectrum. Requiring higher order corrections to be no more than 41% of the tree-level value, we obtain an upper bound of 20 TeV for the heavy Higgses and 12 TeV for the charginos and neutralinos outside defined fine-tuned regions. Read More

We place perturbative unitarity constraints on both the dimensionful and dimensionless couplings in the Next-to-Minimal Supersymmetric Standard Model Higgs Sector. These constraints, plus the requirement that the singlino and/or Higgsino constitutes at least part of the observed dark matter relic abundance, generate upper bounds on the Higgs and neutralino/chargino mass spectrum. We obtain an upper bound of 12 TeV for the charginos and neutralinos and 20 TeV for the heavy Higgses outside defined fine-tuned regions. Read More

We investigate simple extensions of the Standard Model that could lead to the negative values of the top Yukawa coupling still allowed by the ATLAS Higgs results. Integrating out tree-level new physics generates dimension six operators that can lead to large changes to the top Yukawa couplings. If the top Yukawa coupling is negative, there is new physics beneath the TeV scale. Read More

We study the naturalness problem using a model independent bottom up approach by considering models where only the interaction terms needed to cancel the Higgs quadratic divergences are present. If quadratic divergences are canceled by terms linear in the Higgs field, then the collider phenomenology is well covered by current electroweakino and fourth generation searches. If quadratic divergences are canceled by terms bilinear in the Higgs field, then the signatures are highly dependent on the quantum numbers of the new particles. Read More

We introduce a search technique that is sensitive to a broad class of signals with large final state multiplicities. Events are clustered into large radius jets and jet substructure techniques are used to count the number of subjets within each jet. The search consists of a cut on the total number of subjets in the event as well as the summed jet mass and missing energy. Read More

We discuss the relevance of directional detection experiments in the post-discovery era and propose a method to extract the local dark matter phase space distribution from directional data. The first feature of this method is a parameterization of the dark matter distribution function in terms of integrals of motion, which can be analytically extended to infer properties of the global distribution if certain equilibrium conditions hold. The second feature of our method is a decomposition of the distribution function in moments of a model independent basis, with minimal reliance on the ansatz for its functional form. Read More

2011May
Authors: Daniele Alves1, Nima Arkani-Hamed2, Sanjay Arora3, Yang Bai4, Matthew Baumgart5, Joshua Berger6, Matthew Buckley7, Bart Butler8, Spencer Chang9, Hsin-Chia Cheng10, Clifford Cheung11, R. Sekhar Chivukula12, Won Sang Cho13, Randy Cotta14, Mariarosaria D'Alfonso15, Sonia El Hedri16, Rouven Essig17, Jared A. Evans18, Liam Fitzpatrick19, Patrick Fox20, Roberto Franceschini21, Ayres Freitas22, James S. Gainer23, Yuri Gershtein24, Richard Gray25, Thomas Gregoire26, Ben Gripaios27, Jack Gunion28, Tao Han29, Andy Haas30, Per Hansson31, JoAnne Hewett32, Dmitry Hits33, Jay Hubisz34, Eder Izaguirre35, Jared Kaplan36, Emanuel Katz37, Can Kilic38, Hyung-Do Kim39, Ryuichiro Kitano40, Sue Ann Koay41, Pyungwon Ko42, David Krohn43, Eric Kuflik44, Ian Lewis45, Mariangela Lisanti46, Tao Liu47, Zhen Liu48, Ran Lu49, Markus Luty50, Patrick Meade51, David Morrissey52, Stephen Mrenna53, Mihoko Nojiri54, Takemichi Okui55, Sanjay Padhi56, Michele Papucci57, Michael Park58, Myeonghun Park59, Maxim Perelstein60, Michael Peskin61, Daniel Phalen62, Keith Rehermann63, Vikram Rentala64, Tuhin Roy65, Joshua T. Ruderman66, Veronica Sanz67, Martin Schmaltz68, Stephen Schnetzer69, Philip Schuster70, Pedro Schwaller71, Matthew D. Schwartz72, Ariel Schwartzman73, Jing Shao74, Jessie Shelton75, David Shih76, Jing Shu77, Daniel Silverstein78, Elizabeth Simmons79, Sunil Somalwar80, Michael Spannowsky81, Christian Spethmann82, Matthew Strassler83, Shufang Su84, Tim Tait85, Brooks Thomas86, Scott Thomas87, Natalia Toro88, Tomer Volansky89, Jay Wacker90, Wolfgang Waltenberger, Itay Yavin, Felix Yu, Yue Zhao, Kathryn Zurek
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This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Read More