J. Wacker - M. Vos ed.

J. Wacker
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J. Wacker
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M. Vos ed.
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High Energy Physics - Phenomenology (47)
 
High Energy Physics - Experiment (18)
 
High Energy Physics - Theory (5)
 
Cosmology and Nongalactic Astrophysics (5)
 
Astrophysics of Galaxies (2)
 
Astrophysics (1)
 
Physics - Atomic Physics (1)
 
Physics - Strongly Correlated Electrons (1)
 
High Energy Astrophysical Phenomena (1)

Publications Authored By J. Wacker

Over the past decade, a large number of jet substructure observables have been proposed in the literature, and explored at the LHC experiments. Such observables attempt to utilize the internal structure of jets in order to distinguish those initiated by quarks, gluons, or by boosted heavy objects, such as top quarks and W bosons. This report, originating from and motivated by the BOOST2013 workshop, presents original particle-level studies that aim to improve our understanding of the relationships between jet substructure observables, their complementarity, and their dependence on the underlying jet properties, particularly the jet radius and jet transverse momentum. Read More

It has recently been proposed that dark matter could be a thermal relic of 3-to-2 scatterings in a strongly coupled hidden sector. We present explicit classes of strongly coupled gauge theories that admit this behavior. These are QCD-like theories of dynamical chiral symmetry breaking, where the pions play the role of dark matter. Read More

A proton-proton collider with center of mass energy around 100 TeV is the energy frontier machine that is likely to succeed the LHC. One of the primary physics goals will be the continued exploration of weak scale naturalness. Here we focus on the pair-production of stops that decay to a top and a neutralino. Read More

We present a new paradigm for achieving thermal relic dark matter. The mechanism arises when a nearly secluded dark sector is thermalized with the Standard Model after reheating. The freezeout process is a number-changing 3->2 annihilation of strongly-interacting-massive-particles (SIMPs) in the dark sector, and points to sub-GeV dark matter. Read More

QCD is often the dominant background to new physics searches for which jet substructure provides a useful handle. Due to the challenges associated with modeling this background, data-driven approaches are necessary. This paper presents a novel method for determining QCD predictions using templates -- probability distribution functions for jet substructure properties as a function of kinematic inputs. Read More

Results are presented for a variety of SUSY Simplified Models at the 14 TeV LHC as well as a 33 and 100 TeV proton collider. Our focus is on models whose signals are driven by colored production. We present projections of the upper limit and discovery reach in the gluino-neutralino (for both light and heavy flavor decays), squark-neutralino, and gluino-squark Simplified Model planes. 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

2013Nov
Affiliations: 1M. Vos ed., 2M. Vos ed., 3M. Vos ed., 4M. Vos ed., 5M. Vos ed., 6M. Vos ed., 7M. Vos ed., 8M. Vos ed., 9M. Vos ed., 10M. Vos ed., 11M. Vos ed., 12M. Vos ed., 13M. Vos ed., 14M. Vos ed., 15M. Vos ed., 16M. Vos ed., 17M. Vos ed., 18M. Vos ed., 19M. Vos ed., 20M. Vos ed., 21M. Vos ed., 22M. Vos ed., 23M. Vos ed., 24M. Vos ed., 25M. Vos ed., 26M. Vos ed., 27M. Vos ed., 28M. Vos ed., 29M. Vos ed., 30M. Vos ed., 31M. Vos ed., 32M. Vos ed., 33M. Vos ed., 34M. Vos ed., 35M. Vos ed., 36M. Vos ed., 37M. Vos ed., 38M. Vos ed., 39M. Vos ed., 40M. Vos ed., 41M. Vos ed., 42M. Vos ed., 43M. Vos ed., 44M. Vos ed., 45M. Vos ed., 46M. Vos ed., 47M. Vos ed., 48M. Vos ed., 49M. Vos ed., 50M. Vos ed., 51M. Vos ed., 52M. Vos ed., 53M. Vos ed., 54M. Vos ed., 55M. Vos ed., 56M. Vos ed., 57M. Vos ed., 58M. Vos ed., 59M. Vos ed., 60M. Vos ed., 61M. Vos ed., 62M. Vos ed., 63M. Vos ed., 64M. Vos ed., 65M. Vos ed., 66M. Vos ed., 67M. Vos ed., 68M. Vos ed., 69M. Vos ed., 70M. Vos ed., 71M. Vos ed., 72M. Vos ed., 73M. Vos ed., 74M. Vos ed., 75M. Vos ed., 76M. Vos ed., 77M. Vos ed., 78M. Vos ed., 79M. Vos ed., 80M. Vos ed., 81M. Vos ed., 82M. Vos ed., 83M. Vos ed., 84M. Vos ed., 85M. Vos ed., 86M. Vos ed., 87M. Vos ed.

This report of the BOOST2012 workshop presents the results of four working groups that studied key aspects of jet substructure. We discuss the potential of the description of jet substructure in first-principle QCD calculations and study the accuracy of state-of-the-art Monte Carlo tools. Experimental limitations of the ability to resolve substructure are evaluated, with a focus on the impact of additional proton proton collisions on jet substructure performance in future LHC operating scenarios. Read More

We present a summary of results for SUSY Simplified Model searches at future proton colliders: the 14 TeV LHC as well as a 33 TeV proton collider and a 100 TeV proton collider. Upper limits and discovery significances are provided for the gluino-neutralino (for both light and heavy flavor decays), squark-neutralino, and gluino-squark Simplified Model planes. Events are processed with the Snowmass combined detector and Standard Model backgrounds are computed using the Snowmass samples. Read More

This document describes the simulation framework used in the Snowmass Energy Frontier studies for future Hadron Colliders. An overview of event generation with {\sc Madgraph}5 along with parton shower and hadronization with {\sc Pythia}6 is followed by a detailed description of pile-up and detector simulation with {\sc Delphes}3. Details of event generation are included in a companion paper cited within this paper. Read More

This document describes the novel techniques used to simulate the common Snowmass 2013 Energy Frontier Standard Model backgrounds for future hadron colliders. The purpose of many Energy Frontier studies is to explore the reach of high luminosity data sets at a variety of high energy colliders. The generation of high statistics samples which accurately model large integrated luminosities for multiple center-of-mass energies and pile-up environments is not possible using an unweighted event generation strategy -- an approach which relies on event weighting was necessary. Read More

We evaluate the potential of a dedicated search for tth production in the SSDL+2b channel. Such a measurement provides direct access to the top Yukawa coupling, since the sensitivity is not convolved with the loop-level h-gamma-gamma or poorly known hbb coupling, as is the case for present tth searches. Furthermore, susceptibility to uncertainties in the Higgs width can be reduced by considering a ratio of SSDL+2b rates with those of the performed Wh -> WWW* measurement. Read More

The Higgs boson mass and the abundance of dark matter constrain the CMSSM/mSUGRA supersymmetry breaking inputs. A complete map of the CMSSM that is consistent with these two measured quantities is provided. Various "continents," consisting of non-excluded models, can be organized by their dark matter dynamics. 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

There is evidence for a 130 GeV gamma-ray line at the Galactic Center in the Fermi Large Area Telescope data. Dark matter candidates that explain this feature should also annihilate to Standard Model particles, resulting in a continuous spectrum of photons. To study this continuum, we analyze the Fermi data down to 5 GeV, restricted to the inner 3 degrees of the Galaxy. Read More

We study a 2+1 dimensional theory of bosons and fermions with an omega ~ k^2 dispersion relation. The most general interactions consistent with specific symmetries impart fractional statistics to the fermions. Unlike examples involving Chern-Simons gauge theories, our statistical phases derive from the exchange of gapless propagating bosons with marginal interactions. 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

This article introduces a new class of searches for physics beyond the Standard Model that improves the sensitivity to signals with high jet multiplicity. The proposed searches gain access to high multiplicity signals by reclustering events into large-radius, or "fat," jets and by requiring that each event has multiple massive jets. This technique is applied to supersymmetric scenarios in which gluinos are pair-produced and then subsequently decay to final states with either moderate quantities of missing energy or final states without missing energy. Read More

In this report we review recent theoretical progress and the latest experimental results in jet substructure from the Tevatron and the LHC. We review the status of and outlook for calculation and simulation tools for studying jet substructure. Following up on the report of the Boost 2010 workshop, we present a new set of benchmark comparisons of substructure techniques, focusing on the set of variables and grooming methods that are collectively known as "top taggers". Read More

We consider a comprehensive set of simplified models that contribute to final states with top and bottom quarks at the LHC. These simplified models are used to create minimal search strategies that ensure optimal coverage of new heavy flavor physics involving the pair production of color octets and triplets. We provide a set of benchmarks that are representative of model space, which can be used by experimentalists to perform their own optimization of search strategies. Read More

Recent evidence from the LHC for the Higgs boson with mass between 142 GeV < m_h < 147GeV points to PeV-scale Split Supersymmetry. This article explores the consequences of a Higgs mass in this range and possible discovery modes for Split Susy. Moderate lifetime gluinos, with decay lengths in the 25 microns to 10 years range, are its imminent smoking gun signature. 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
Affiliations: 1Editor, 2Editor, 3Editor, 4Editor, 5Editor, 6Editor, 7Editor, 8Editor, 9Editor, 10Editor, 11Editor, 12Editor, 13Editor, 14Editor, 15Editor, 16Editor, 17Editor, 18Editor, 19Editor, 20Editor, 21Editor, 22Editor, 23Editor, 24Editor, 25Editor, 26Editor, 27Editor, 28Editor, 29Editor, 30Editor, 31Editor, 32Editor, 33Editor, 34Editor, 35Editor, 36Editor, 37Editor, 38Editor, 39Editor, 40Editor, 41Editor, 42Editor, 43Editor, 44Editor, 45Editor, 46Editor, 47Editor, 48Editor, 49Editor, 50Editor, 51Editor, 52Editor, 53Editor, 54Editor, 55Editor, 56Editor, 57Editor, 58Editor, 59Editor, 60Editor, 61Editor, 62Editor, 63Editor, 64Editor, 65Editor, 66Editor, 67Editor, 68Editor, 69Editor, 70Editor, 71Editor, 72Editor, 73Editor, 74Editor, 75Editor, 76Editor, 77Editor, 78Editor, 79Editor, 80Editor, 81Editor, 82Editor, 83Editor, 84Editor, 85Editor, 86Editor, 87Editor, 88Editor, 89Editor, 90Editor

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

This work explores the potential reach of the 7 TeV LHC to new colored states in the context of simplified models and addresses the issue of which search regions are necessary to cover an extensive set of event topologies and kinematic regimes. This article demonstrates that if searches are designed to focus on specific regions of phase space, then new physics may be missed if it lies in unexpected corners. Simple multiregion search strategies can be designed to cover all of kinematic possibilities. Read More

A new jet observable, dipolarity, is introduced that can distinguish whether a pair of subjets arises from a color singlet source. This observable is incorporated into the HEPTopTagger and is shown to improve discrimination between top jets and QCD jets for moderate to high pT. Read More

We present the report of the hadronic working group of the BOOST2010 workshop held at the University of Oxford in June 2010. The first part contains a review of the potential of hadronic decays of highly boosted particles as an aid for discovery at the LHC and a discussion of the status of tools developed to meet the challenge of reconstructing and isolating these topologies. In the second part, we present new results comparing the performance of jet grooming techniques and top tagging algorithms on a common set of benchmark channels. Read More

Dark matter density profiles based upon Lambda-CDM cosmology motivate an ansatz velocity distribution function with fewer high velocity particles than the Maxwell-Boltzmann distribution or proposed variants. The high velocity tail of the distribution is determined by the outer slope of the dark matter halo, the large radius behavior of the Galactic dark matter density. N-body simulations of Galactic halos reproduce the high velocity behavior of this ansatz. Read More

Theories of dark matter that support bound states are an intriguing possibility for the identity of the missing mass of the Universe. This article proposes a class of models of supersymmetric composite dark matter where the interactions with the Standard Model communicate supersymmetry breaking to the dark sector. In these models supersymmetry breaking can be treated as a perturbation on the spectrum of bound states. Read More

The first search for supersymmetry from ATLAS with 70/nb of integrated luminosity extends the Tevatron' s reach for colored particles that decay into jets plus missing transverse energy. For gluinos that decay directly or through a one step cascade into the LSP and two jets, the mass range m_g < 205 GeV is disfavored by the ATLAS searches, regardless of the mass of the LSP. In some cases the coverage extends up to m_g ~ 295 GeV, already surpassing the Tevatron's reach for compressed supersymmetry spectra. Read More

New Abelian vector bosons can kinetically mix with the hypercharge gauge boson of the Standard Model. This letter computes the model independent limits on vector bosons with masses from 1 GeV to 1 TeV. The limits arise from the numerous e+e- experiments that have been performed in this energy range and bound the kinetic mixing by epsilon < 0. Read More

The XENON100 and CRESST experiments will directly test the inelastic dark matter explanation for DAMA's 8.9? sigma anomaly. This article discusses how predictions for direct detection experiments depend on uncertainties in quenching factor measurements, the dark matter interaction with the Standard Model and the halo velocity distribution. Read More

Composite dark matter is a natural setting for implementing inelastic dark matter - the O(100 keV) mass splitting arises from spin-spin interactions of constituent fermions. In models where the constituents are charged under an axial U(1) gauge symmetry that also couples to the Standard Model quarks, dark matter scatters inelastically off Standard Model nuclei and can explain the DAMA/LIBRA annual modulation signal. This article describes the early Universe cosmology of a minimal implementation of a composite inelastic dark matter model where the dark matter is a meson composed of a light and a heavy quark. Read More

Multijet plus missing energy searches provide universal coverage for theories that have new colored particles that decay into a dark matter candidate and jets. These signals appear at the LHC further out on the missing energy tail than two-to-two scattering indicates. The simplicity of the searches at the LHC contrasts sharply with the Tevatron where more elaborate searches are necessary to separate signal from background. Read More

The Large Hadron Collider presents an unprecedented opportunity to probe the realm of new physics in the TeV region and shed light on some of the core unresolved issues of particle physics. These include the nature of electroweak symmetry breaking, the origin of mass, the possible constituent of cold dark matter, new sources of CP violation needed to explain the baryon excess in the universe, the possible existence of extra gauge groups and extra matter, and importantly the path Nature chooses to resolve the hierarchy problem - is it supersymmetry or extra dimensions. Many models of new physics beyond the standard model contain a hidden sector which can be probed at the LHC. Read More

Supersymmetric QED hydrogen-like bound states are remarkably similar to non-supersymmetric hydrogen, including an accidental degeneracy of the fine structure and which is broken by the Lamb shift. This article classifies the states, calculates the leading order spectrum, and illustrates the results in several limits. The relation to other non-relativistic bound states is explored. Read More

This article classifies Little Higgs models that have collective quartic couplings. There are two classes of collective quartics: Special Cosets and Special Quartics. After taking into account dangerous singlets, the smallest Special Coset models are SU(5)/SO(5) and SU(6)/Sp(6). Read More

Recent experimental results indicate that the dark matter sector may have a non-minimal structure with a spectrum of states and interactions. Inelastic scattering has received particular attention in light of DAMA's annual modulation signal. Composite inelastic dark matter (CiDM) provides a dynamical origin for the mass splittings in inelastic dark matter models. Read More

Inelastic dark matter reconciles the DAMA anomaly with other null direct detection experiments and points to a non-minimal structure in the dark matter sector. In addition to the dominant inelastic interaction, dark matter scattering may have a subdominant elastic component. If these elastic interactions are suppressed at low momentum transfer, they will have similar nuclear recoil spectra to inelastic scattering events. Read More

Atom interferometry is a rapidly advancing field and this Letter proposes an experiment based on existing technology that can search for new short distance forces. With current technology it is possible to improve the sensitivity by up to a factor of 10^2 and near-future advances will be able to rewrite the limits for forces with ranges from 100 um to 1 km. Read More

Peaking consistently in June for nearly eleven years, the annual modulation signal reported by DAMA/NaI and DAMA/LIBRA offers strong evidence for the identity of dark matter. DAMA's signal strongly suggest that dark matter inelastically scatters into an excited state split by O(100 keV). We propose that DAMA is observing hyperfine transitions of a composite dark matter particle. Read More

Many models of electroweak symmetry breaking have an additional light pseudoscalar. If the Higgs boson can decay to a new pseudoscalar, LEP searches for the Higgs can be significantly altered and the Higgs can be as light as 86 GeV. Discovering the Higgs boson in these models is challenging when the pseudoscalar is lighter than 10 GeV because it decays dominantly into tau leptons. Read More

We present a proposal for performing model-independent jets plus missing energy searches. Currently, these searches are optimized for mSUGRA and are consequently not sensitive to all kinematically-accessible regions of parameter space. We show that the reach of these searches can be broadened by setting limits on the differential cross section as a function of the total visible energy and the missing energy. Read More

This letter describes how to perform searches over the complete kinematically-allowed parameter space for new pair-produced color octet particles that each subsequently decay into two jets plus missing energy at the Tevatron. This letter shows that current searches can miss otherwise discoverable spectra of particles due to CMSSM-motivated cuts. Optimizing the HT and MET cuts expands the sensitivity of these searches. Read More

The six Higgs doublet model is a minimal extension of the Standard Model that addresses dark matter and gauge coupling unification. Another Higgs doublet in a 5 representation of a discrete symmetry group, such as S_6, is added to the SM. The lightest components of the 5-Higgs are neutral, stable and serve as dark matter so long as the discrete symmetry is not broken. Read More

In theories with multiple vacua, reheating to a temperature greater than the height of a barrier can stimulate transitions from a desirable metastable vacuum to a lower energy state. We discuss the constraints this places on various theories and demonstrate that in a class of supersymmetric models this transition does not occur even for arbitrarily high reheating temperature. Read More

We study extensions of the Standard Model where the Higgs boson dominantly decays via a cascade to four tau leptons, and discuss whether this decay is visible at the Tevatron. We find that with an integrated luminosity of 6 fb^-1, there can be excesses in multi-lepton events in several channels for a Higgs boson of a mass = 110 GeV. Read More

The presence of many axion fields in four-dimensional string vacua can lead to a simple, radiatively stable realization of chaotic inflation. Read More

Long lived gluinos are the trademark of split supersymmetry. They form R-hadrons that, when charged, efficiently lose energy in matter via ionisation. Independent of R-spectroscopy and initial hadronization, a fraction of R-hadrons become charged while traversing a detector. Read More

An upper limit on the masses of scalar superpartners in split supersymmetry is found by considering cosmological constraints on long-lived gluinos. Over most of parameter space, the most stringent constraint comes from big bang nucleosynthesis. A TeV mass gluino must have a lifetime of less than 100 seconds to avoid altering the abundances of D and Li-6. Read More