Search

With the increasing usage of machine-learning in high-energy physics analyses, the publication of the trained models in a reusable form has become a crucial question for analysis preservation and reuse. The complexity of these models creates practical issues for both reporting them accurately and for ensuring the stability of their behaviours in different environments and over extended timescales. In this note we discuss the current state of affairs, highlighting specific practical issues and focusing on the most promising technical and strategic approaches to ensure trustworthy analysis-preservation. This material originated from discussions in the LHC Reinterpretation Forum and the 2023 PhysTeV workshop at Les Houches., Comment: 12 pages; v2: added funding acknowledgement

Using the GAMBIT global fitting framework, we constrain the MSSM with an eV-scale gravitino as the lightest supersymmetric particle, and the six electroweakinos (neutralinos and charginos) as the only other light new states. We combine 15 ATLAS and 12 CMS searches at 13\,TeV, along with a large collection of ATLAS and CMS measurements of Standard Model signatures. This model, which we refer to as the $\tilde G$-EWMSSM, exhibits quite varied collider phenomenology due to its many permitted electroweakino production processes and decay modes. Characteristic $\tilde G$-EWMSSM signal events have two or more Standard Model bosons and missing energy due to the escaping gravitinos. While much of the $\tilde G$-EWMSSM parameter space is excluded, we find several viable parameter regions that predict phenomenologically rich scenarios with multiple neutralinos and charginos within the kinematic reach of the LHC during Run 3, or the High Luminosity LHC. In particular, we identify scenarios with Higgsino-dominated electroweakinos as light as 140 GeV that are consistent with our combined set of collider searches and measurements. The full set of $\tilde G$-EWMSSM parameter samples and GAMBIT input files generated for this work is available via Zenodo., Comment: 38 pages, 12 figures, 5 tables

We introduce the GAMBIT Universal Model Machine (GUM), a tool for automatically generating code for the global fitting software framework GAMBIT, based on Lagrangian-level inputs. GUM accepts models written symbolically in FeynRules and SARAH formats, and can use either tool along with MadGraph and CalcHEP to generate GAMBIT model, collider, dark matter, decay and spectrum code, as well as GAMBIT interfaces to corresponding versions of SPheno, micrOMEGAs, Pythia and Vevacious (C++). In this paper we describe the features, methods, usage, pathways, assumptions and current limitations of GUM. We also give a fully worked example, consisting of the addition of a Majorana fermion simplified dark matter model with a scalar mediator to GAMBIT via GUM, and carry out a corresponding fit., Comment: 32 pages, 6 figures, 3 tables

We assess the status of a wide class of WIMP dark matter (DM) models in light of the latest experimental results using the global fitting framework $\textsf{GAMBIT}$. We perform a global analysis of effective field theory (EFT) operators describing the interactions between a gauge-singlet Dirac fermion and the Standard Model quarks, the gluons and the photon. In this bottom-up approach, we simultaneously vary the coefficients of 14 such operators up to dimension 7, along with the DM mass, the scale of new physics and several nuisance parameters. Our likelihood functions include the latest data from $\mathit{Planck}$, direct and indirect detection experiments, and the LHC. For DM masses below 100 GeV, we find that it is impossible to satisfy all constraints simultaneously while maintaining EFT validity at LHC energies. For new physics scales around 1 TeV, our results are influenced by several small excesses in the LHC data and depend on the prescription that we adopt to ensure EFT validity. Furthermore, we find large regions of viable parameter space where the EFT is valid and the relic density can be reproduced, implying that WIMPs can still account for the DM of the universe while being consistent with the latest data., Comment: 37 pages, 11 figures, 5 tables; v2: matches EPJC version

Physical theories that depend on many parameters or are tested against data from many different experiments pose unique challenges to statistical inference. Many models in particle physics, astrophysics and cosmology fall into one or both of these categories. These issues are often sidestepped with statistically unsound ad hoc methods, involving intersection of parameter intervals estimated by multiple experiments, and random or grid sampling of model parameters. Whilst these methods are easy to apply, they exhibit pathologies even in low-dimensional parameter spaces, and quickly become problematic to use and interpret in higher dimensions. In this article we give clear guidance for going beyond these procedures, suggesting where possible simple methods for performing statistically sound inference, and recommendations of readily-available software tools and standards that can assist in doing so. Our aim is to provide any physicists lacking comprehensive statistical training with recommendations for reaching correct scientific conclusions, with only a modest increase in analysis burden. Our examples can be reproduced with the code publicly available at https://doi.org/10.5281/zenodo.4322283., Comment: 15 pages, 4 figures. extended discussions. closely matches version accepted for publication

The evaluation of higher-order cross-sections is an important component in the search for new physics, both at hadron colliders and elsewhere. For most new physics processes of interest, total cross-sections are known at next-to-leading order (NLO) in the strong coupling $\alpha_s$, and often beyond, via either higher-order terms at fixed powers of $\alpha_s$, or multi-emission resummation. However, the computation time for such higher-order cross-sections is prohibitively expensive, and precludes efficient evaluation in parameter-space scans beyond two dimensions. Here we describe the software tool $\textsf{xsec}$, which allows for fast evaluation of cross-sections based on the use of machine-learning regression, using distributed Gaussian processes trained on a pre-generated sample of parameter points. This first version of the code provides all NLO Minimal Supersymmetric Standard Model strong-production cross-sections at the LHC, for individual flavour final states, evaluated in a fraction of a second. Moreover, it calculates regression errors, as well as estimates of errors from higher-order contributions, from uncertainties in the parton distribution functions, and from the value of $\alpha_s$. While we focus on a specific phenomenological model of supersymmetry, the method readily generalises to any process where it is possible to generate a sufficient training sample., Comment: Accepted version

We report on the status of efforts to improve the reinterpretation of searches and measurements at the LHC in terms of models for new physics, in the context of the LHC Reinterpretation Forum. We detail current experimental offerings in direct searches for new particles, measurements, technical implementations and Open Data, and provide a set of recommendations for further improving the presentation of LHC results in order to better enable reinterpretation in the future. We also provide a brief description of existing software reinterpretation frameworks and recent global analyses of new physics that make use of the current data., Comment: 58 pages, minor revision following comments from SciPost referees

This report presents the activities of the `New Physics' working group for the `Physics at TeV Colliders' workshop (Les Houches, France, 10--28 June, 2019). These activities include studies of direct searches for new physics, approaches to exploit published data to constrain new physics, as well as the development of tools to further facilitate these investigations. Benefits of machine learning for both the search for new physics and the interpretation of these searches are also presented., Comment: Proceedings of the BSM Session of the Les Houches 2019 workshop, 227 pages

Searches for supersymmetric electroweakinos have entered a crucial phase, as the integrated luminosity of the Large Hadron Collider is now high enough to compensate for their weak production cross-sections. Working in a framework where the neutralinos and charginos are the only light sparticles in the Minimal Supersymmetric Standard Model, we use gambit to perform a detailed likelihood analysis of the electroweakino sector. We focus on the impacts of recent ATLAS and CMS searches with 36 fb$^{-1}$ of 13 TeV proton-proton collision data. We also include constraints from LEP and invisible decays of the $Z$ and Higgs bosons. Under the background-only hypothesis, we show that current LHC searches do not robustly exclude any range of neutralino or chargino masses. However, a pattern of excesses in several LHC analyses points towards a possible signal, with neutralino masses of $(m_{\tilde{\chi}_1^0}, m_{\tilde{\chi}_2^0}, m_{\tilde{\chi}_3^0}, m_{\tilde{\chi}_4^0})$ = (8-155, 103-260, 130-473, 219-502) GeV and chargino masses of $(m_{\tilde{\chi}_1^{\pm}}, m_{\tilde{\chi}_2^{\pm}})$ = (104-259, 224-507) GeV at the 95% confidence level. The lightest neutralino is mostly bino, with a possible modest Higgsino or wino component. We find that this excess has a combined local significance of $3.3\sigma$, subject to a number of cautions. If one includes LHC searches for charginos and neutralinos conducted with 8 TeV proton-proton collision data, the local significance is lowered to 2.9$\sigma$. We briefly consider the implications for dark matter, finding that the correct relic density can be obtained through the Higgs-funnel and $Z$-funnel mechanisms, even assuming that all other sparticles are decoupled. All samples, gambit input files and best-fit models from this study are available on Zenodo., Comment: 38 pages, 16 figures, v3 is the version accepted by EPJC

e-ASTROGAM (enhanced ASTROGAM) is a breakthrough Observatory space mission, with a detector composed by a Silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the study of the non-thermal Universe in the photon energy range from 0.3 MeV to 3 GeV - the lower energy limit can be pushed to energies as low as 150 keV for the tracker, and to 30 keV for calorimetric detection. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. Thanks to its performance in the MeV-GeV domain, substantially improving its predecessors, e-ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on the surroundings. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous generation instruments, e-ASTROGAM will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LIGO-Virgo-GEO600-KAGRA, SKA, ALMA, E-ELT, TMT, LSST, JWST, Athena, CTA, IceCube, KM3NeT, and LISA., Comment: Published on Journal of High Energy Astrophysics (Elsevier)

One of the simplest viable models for dark matter is an additional neutral scalar, stabilised by a $\mathbb{Z}_2$ symmetry. Using the GAMBIT package and combining results from four independent samplers, we present Bayesian and frequentist global fits of this model. We vary the singlet mass and coupling along with 13 nuisance parameters, including nuclear uncertainties relevant for direct detection, the local dark matter density, and selected quark masses and couplings. We include the dark matter relic density measured by Planck, direct searches with LUX, PandaX, SuperCDMS and XENON100, limits on invisible Higgs decays from the Large Hadron Collider, searches for high-energy neutrinos from dark matter annihilation in the Sun with IceCube, and searches for gamma rays from annihilation in dwarf galaxies with the Fermi-LAT. Viable solutions remain at couplings of order unity, for singlet masses between the Higgs mass and about 300 GeV, and at masses above $\sim$1 TeV. Only in the latter case can the scalar singlet constitute all of dark matter. Frequentist analysis shows that the low-mass resonance region, where the singlet is about half the mass of the Higgs, can also account for all of dark matter, and remains viable. However, Bayesian considerations show this region to be rather fine-tuned., Comment: 19 pages, 5 figures, matches published version. v3 updates the Zenodo URL for supplementary data (available at https://doi.org/10.5281/zenodo.801510)

We study the seven-dimensional Minimal Supersymmetric Standard Model (MSSM7) with the new GAMBIT software framework, with all parameters defined at the weak scale. Our analysis significantly extends previous weak-scale, phenomenological MSSM fits, by adding more and newer experimental analyses, improving the accuracy and detail of theoretical predictions, including dominant uncertainties from the Standard Model, the Galactic dark matter halo and the quark content of the nucleon, and employing novel and highly-efficient statistical sampling methods to scan the parameter space. We find regions of the MSSM7 that exhibit co-annihilation of neutralinos with charginos, stops and sbottoms, as well as models that undergo resonant annihilation via both light and heavy Higgs funnels. We find high-likelihood models with light charginos, stops and sbottoms that have the potential to be within the future reach of the LHC. Large parts of our preferred parameter regions will also be accessible to the next generation of direct and indirect dark matter searches, making prospects for discovery in the near future rather good., Comment: 31 pages, 14 figures; v2 matches version accepted by EPJC; v3 has corrected link to supplementary data on Zenodo

We describe ColliderBit, a new code for the calculation of high energy collider observables in theories of physics beyond the Standard Model (BSM). ColliderBit features a generic interface to BSM models, a unique parallelised Monte Carlo event generation scheme suitable for large-scale supercomputer applications, and a number of LHC analyses, covering a reasonable range of the BSM signatures currently sought by ATLAS and CMS. ColliderBit also calculates likelihoods for Higgs sector observables, and LEP searches for BSM particles. These features are provided by a combination of new code unique to ColliderBit, and interfaces to existing state-of-the-art public codes. ColliderBit is both an important part of the GAMBIT framework for BSM inference, and a standalone tool for efficiently applying collider constraints to theories of new physics., Comment: 31 pages, 7 figures, 17 tables. Replacement version accepted by EPJC

We present the most comprehensive global fits to date of three supersymmetric models motivated by grand unification: the Constrained Minimal Supersymmetric Standard Model (CMSSM), and its Non-Universal Higgs Mass generalisations NUHM1 and NUHM2. We include likelihoods from a number of direct and indirect dark matter searches, a large collection of electroweak precision and flavour observables, direct searches for supersymmetry at LEP and Runs I and II of the LHC, and constraints from Higgs observables. Our analysis improves on existing results not only in terms of the number of included observables, but also in the level of detail with which we treat them, our sampling techniques for scanning the parameter space, and our treatment of nuisance parameters. We show that stau co-annihilation is now ruled out in the CMSSM at more than 95\% confidence. Stop co-annihilation turns out to be one of the most promising mechanisms for achieving an appropriate relic density of dark matter in all three models, whilst avoiding all other constraints. We find high-likelihood regions of parameter space featuring light stops and charginos, making them potentially detectable in the near future at the LHC. We also show that tonne-scale direct detection will play a largely complementary role, probing large parts of the remaining viable parameter space, including essentially all models with multi-TeV neutralinos., Comment: 50 pages, 21 figures, 7 tables, v2 accepted for publication in EPJC, v3 update Zenodo link

We describe the open-source global fitting package GAMBIT: the Global And Modular Beyond-the-Standard-Model Inference Tool. GAMBIT combines extensive calculations of observables and likelihoods in particle and astroparticle physics with a hierarchical model database, advanced tools for automatically building analyses of essentially any model, a flexible and powerful system for interfacing to external codes, a suite of different statistical methods and parameter scanning algorithms, and a host of other utilities designed to make scans faster, safer and more easily-extendible than in the past. Here we give a detailed description of the framework, its design and motivation, and the current models and other specific components presently implemented in GAMBIT. Accompanying papers deal with individual modules and present first GAMBIT results. GAMBIT can be downloaded from gambit.hepforge.org., Comment: 84 pages, 8 Figures. Code available at http://gambit.hepforge.org. v2: Main paper now matches version accepted by EPJC. This version also adds an addendum submitted to EPJC on Mathematica support in GAMBIT v1.1

The precise measurement of cosmic-ray antiparticles serves as important means for identifying the nature of dark matter. Recent years showed that identifying the nature of dark matter with cosmic-ray positrons and higher energy antiprotons is difficult, and has lead to a significantly increased interest in cosmic-ray antideuteron searches. Antideuterons may also be generated in dark matter annihilations or decays, offering a potential breakthrough in unexplored phase space for dark matter. Low-energy antideuterons are an important approach because the flux from dark matter interactions exceeds the background flux by more than two orders of magnitude in the low-energy range for a wide variety of models. This review is based on the "dbar14 - dedicated cosmic-ray antideuteron workshop", which brought together theorists and experimentalists in the field to discuss the current status, perspectives, and challenges for cosmic-ray antideuteron searches and discusses the motivation for antideuteron searches, the theoretical and experimental uncertainties of antideuteron production and propagation in our Galaxy, as well as give an experimental cosmic-ray antideuteron search status update. This report is a condensed summary of the article "Review of the theoretical and experimental status of dark matter identification with cosmic-ray antideuteron" (arXiv:1505.07785)., Comment: 9 pages, 4 figures, ICRC 2015 proceedings

Recent years have seen increased theoretical and experimental effort towards the first-ever detection of cosmic-ray antideuterons, in particular as an indirect signature of dark matter annihilation or decay. In contrast to indirect dark matter searches using positrons, antiprotons, or gamma-rays, which suffer from relatively high and uncertain astrophysical backgrounds, searches with antideuterons benefit from very suppressed conventional backgrounds, offering a potential breakthrough in unexplored phase space for dark matter. This article is based on the first dedicated cosmic-ray antideuteron workshop, which was held at UCLA in June 2014. It reviews broad classes of dark matter candidates that result in detectable cosmic-ray antideuteron fluxes, as well as the status and prospects of current experimental searches. The coalescence model of antideuteron production and the influence of antideuteron measurements at particle colliders are discussed. This is followed by a review of the modeling of antideuteron propagation through the magnetic fields, plasma currents, and molecular material of our Galaxy, the solar system, the Earth's geomagnetic field, and the atmosphere. Finally, the three ongoing or planned experiments that are sensitive to cosmic-ray antideuterons, BESS, AMS-02, and GAPS, are detailed. As cosmic-ray antideuteron detection is a rare event search, multiple experiments with orthogonal techniques and backgrounds are essential. Many theoretical and experimental groups have contributed to these studies over the last decade, this review aims to provide the first coherent discussion of the relevant dark matter theories that antideuterons probe, the challenges to predictions and interpretations of antideuteron signals, and the experimental efforts toward cosmic antideuteron detection., Comment: 72 pages, 20 figures

Antideuterons are a potential messenger for dark matter annihilation or decay in our own galaxy, with very low backgrounds expected from astrophysical processes. The standard coalescence model of antideuteron formation, while simple to implement, is shown to be under considerable strain by recent data from the LHC. We suggest a new empirically based model, with only one free parameter, which is better able to cope with these data, and we explore the consequences of the model for dark matter searches., Comment: 19 pages, 15 figures, C++ code with parametrised cross sections can be found in the ancillary folder, v2 fixes important missing references

ATLAS recently reported a $3\sigma$ excess in a leptonic-$Z+E_T^{\rm miss}$ channel. This was interpreted in the literature in a simplified General Gauge Mediation model containing a gluino, a higgsino next-to-lightest supersymmetric particle (NLSP) and a gravitino lightest supersymmetric particle (LSP). We test the consistency of this explanation in lieu of the results of the corresponding search in CMS, and other LHC searches for New Physics. Due to non-decoupling effects from squarks the parameter space of these models is split into two regions; in one region additional leptons via top quark production is expected, while the other region sees a large probability for zero-lepton events. After combining the relevant constraints we find that these models cannot explain the ATLAS excess., Comment: Extended discussion of results, added two figures, minor corrections. 7 pages, 6 figures

Supersymmetric models with R-parity violation (RPV) have become more popular following the lack of any excess of missing energy events at the 8 TeV LHC. To identify such models, the suggested searches generally rely on the decay products of the (effectively) lightest supersymmetric particle (LSP), with signals that depend on the identity of the LSP and the relevant RPV operators. Here we look at the prospects for detecting RPV chargino decays at the LHC and find substantial patches of parameter space in the Minimal Supersymmetric Standard Model with possibly spectacular signatures, such as three charged-lepton resonances., Comment: Version published in JHEP

The CMS experiment recently reported an excess consistent with an invariant mass edge in opposite-sign same flavor (OSSF) leptons, when produced in conjunction with at least two jets and missing transverse momentum. We provide an interpretation of the edge in terms of (anti-)squark pair production followed by the `golden cascade' decay for one of the squarks: $\tilde q \rightarrow \tilde\chi_2^0 q \to \tilde l l q \to \tilde\chi_1^0 q l l$ in the minimal supersymmetric standard model (MSSM). A simplified model involving binos, winos, an on-shell slepton, and the first two generations of squarks fits the event rate and the invariant mass edge. We check consistency with a recent ATLAS search in a similar region, finding that much of the good-fit parameter space is still allowed at the 95% confidence level (CL). However, a combination of other LHC searches, notably two-lepton stop pair searches and jets plus $p_T^{\rm miss}$, rule out all of the remaining parameter space at the 95% CL., Comment: 7 pages, 11 figures, v2 fixes problem with axis of Fig. 1 and has some minor changes to text, v3 is a significant revision including new LHC searches which rules out the golden channel interpretation at 95$\%$ confidence level, v4 corrects a mistake in the axis labels on some figures

We investigate the production of antideuterons from decaying dark matter, using gravitinos in supersymmetric models with trilinear R-parity violating (RPV) operators as an example. The model used for antideuteron formation is shown to induce large uncertainties in the predicted flux, comparable to uncertainties from cosmic-ray propagation models. We improve on the formation model by tuning hadronization and coalesence parameters in Monte Carlo simulations to better reproduce the hadron spectra relevant for antideuteron production. In light of current bounds on fluxes and future prospects from the AMS-II and GAPS experiments we set limits on RPV couplings as a function of the gravitino mass., Comment: Updated; corresponds to version published in Phys. Rev. D. 14 pages, 9 figures

Supersymmetric models with a small neutralino-chargino mass difference, and as a result metastable charginos, have been a popular topic of investigation in collider phenomenology, e.g. in anomaly-mediated models of supersymmetry breaking. Recently, the absence of any supersymmetric signal at the 8 TeV LHC data has led to significant interest in the so-called Natural SUSY models with light higgsinos. These models also have a naturally small neutralino-chargino mass difference. However, we show here that when relevant indirect constraints from results at the LHC and elsewhere are applied, this possibility is heavily constrained within the Minimal Supersymmetric Standard Model (MSSM): massive metastable higgsinos are not a signature of Natural SUSY., Comment: Extended discussion, updated references, matches version to appear in JHEP

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. We also study the sensitivity of jet substructure observables to the uncertainties in Monte Carlo predictions., Comment: Report of the hadronic working group of the BOOST2010 workshop, University of Oxford, 22-25 June, 2010. Editors: M. Karagoz, G. Salam, M. Spannowsky and M. Vos. v2 published in EPJ C. 19 pages, double column, uses EPJ C style for latex

We present a collection of signatures for physics beyond the standard model that need to be explored at the LHC. First, are presented various tools developed to measure new particle masses in scenarios where all decays include an unobservable particle. Second, various aspects of supersymmetric models are discussed. Third, some signatures of models of strong electroweak symmetry are discussed. In the fourth part, a special attention is devoted to high mass resonances, as the ones appearing in models with warped extra dimensions. Finally, prospects for models with a hidden sector/valley are presented. Our report, which includes brief experimental and theoretical reviews as well as original results, summarizes the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 8-26 June, 2009)., Comment: 189 pages

We study the charged cosmic rays arising from the slow decay of gravitino dark matter within supersymmetric scenarios with trilinear R-parity violation. It is shown that operators of the LLE type can very well account for the recent anomalies in cosmic ray electron and positron data reported by PAMELA, ATIC and Fermi LAT, without violating any other bounds. This scenario will soon be tested by the Fermi LAT data on diffuse gamma ray emission., Comment: To appear in the proceedings of EPS-HEP 2009, Krakow, Poland

We study photonic, neutrino and charged particle signatures from slow decays of gravitino dark matter in supersymmetric theories where R-parity is explicitly broken by trilinear operators. Photons and (anti-)fermions from loop and tree-level processes give rise to spectra with distinct features, which, if observed, can give crucial input on the possible mass of the gravitino and the magnitude and flavour structure of R-violating operators. Within this framework, we make detailed comparisons of the theoretical predictions to the recent experimental data from PAMELA, ATIC and Fermi LAT., Comment: Version published in Phys. Lett. B

Recently, a claim of possible evidence for Dark Matter in data from the Fermi LAT experiment was made by Goodenough and Hooper [8]. We test the Dark Matter properties consistent with their claim in terms of the MSSM by a 24-dimensional parameter scan using nested sampling, excluding all but a very small region of the MSSM. Although this claim is very preliminary, and not made by the Fermi LAT experiment, our scan shows a possible approach for the analysis of future firm evidence from an indirect detection experiment, and its potential for heavily constraining models., Comment: 5 pages, 3 figures

Decay-frame Kinematics (DK) has previously been introduced as a technique to reconstruct neutralino masses from their three-body decays to leptons. This work is an extension to the case of two-body decays through on-shell sleptons, with Monte Carlo simulation of LHC collisions demonstrating reconstruction of neutralino masses for the SPS1a benchmark point., Comment: 17 pages, 5 figures

This brief review deals with recent interest in the prospects of observing a Massive Metastable Charged Particle (MMCP) at the Large Hadron Collider (LHC), and measuring its properties there. We discuss the motivation for scenarios with MMCPs in a phenomenological context, focusing on supersymmetric models that allow us to explore the expected experimental signatures of MMCPs at the LHC. We review current bounds and give estimates of the LHC reach in terms of MMCP masses., Comment: 16 pages, 1 figure. Minor changes to text, three references added. New version as published in MPLA

Recently there has been much interest in the use of single-jet mass and jet substructure to identify boosted particles decaying hadronically at the LHC. We develop these ideas to address the challenging case of a neutralino decaying to three quarks in models with baryonic violation of R-parity. These decays have previously been found to be swamped by QCD backgrounds. We demonstrate for the first time that such a decay might be observed directly at the LHC with high significance, by exploiting characteristics of the scales at which its composite jet breaks up into subjets., Comment: 5 pages, 3 figures; updated to reflect content of published paper

We study gravitino dark matter and slow gravitino decays within the framework of R-violating supersymmetry, with particular emphasis on the flavour dependence of the branching ratios and the allowed R-violating couplings. The dominant decay modes and final state products turn out to be very sensitive to the R-violating hierarchies. Mixing effects can be crucial in correctly deriving the relative magnitude of the various contributions, particularly for heavy flavours with phase space suppression. The study of the strength of different decay rates for the gravitino is also correlated to collider signatures expected from decays of the Next-to-Lightest Supersymmetric Particle (NLSP) and to single superparticle production., Comment: 20 pages, 7 figures; v2 also includes photons from three-body decays in coupling limits, one additional author, matches version to appear in PLB

We suggest an NMSSM scenario, motivated by dark matter constraints, that may disguise itself as a much simpler mSUGRA scenario at the LHC. We show how its non-minimal nature can be revealed, and the bino--singlino mass difference measured, by looking for soft leptons., Comment: 13 pages, 4 figures

This collection of studies on new physics at the LHC constitutes the report of the supersymmetry working group at the Workshop `Physics at TeV Colliders', Les Houches, France, 2007. They cover the wide spectrum of phenomenology in the LHC era, from alternative models and signatures to the extraction of relevant observables, the study of the MSSM parameter space and finally to the interplay of LHC observations with additional data expected on a similar time scale. The special feature of this collection is that while not each of the studies is explicitely performed together by theoretical and experimental LHC physicists, all of them were inspired by and discussed in this particular environment., Comment: SUSY workking group report: Les Houches 2007

This review presents flavour related issues in the production and decays of heavy states at LHC, both from the experimental side and from the theoretical side. We review top quark physics and discuss flavour aspects of several extensions of the Standard Model, such as supersymmetry, little Higgs model or models with extra dimensions. This includes discovery aspects as well as measurement of several properties of these heavy states. We also present public available computational tools related to this topic., Comment: Report of Working Group 1 of the CERN Workshop ``Flavour in the era of the LHC'', Geneva, Switzerland, November 2005 -- March 2007

We present our work on reconstructing sparticle masses in purely hadronic decay chains, using the $k_T$ jet-algorithm on Monte Carlo simulated events at LHC energies., Comment: 3 pages, 1 figure, contributed to the proceedings of the EPS HEP 2007 Conference, Manchester (UK)

We study radiative gravitino decay within the framework of R-violating supersymmetry. For trilinear R-violating couplings that involve the third generation of fermions, or for light gravitinos, we find that the radiative loop-decay $\tilde{G} \to \gamma \nu$ dominates over the tree-level ones for a wide set of parameters. We calculate the gravitino decay width and study its implications for cosmology and collider physics. Slow-decaying gravitinos are good dark matter candidates, for a range of parameters that would also predict observable R-violating signatures in colliders. In general the branching ratios are very dependent on the relative hierarchies of R-violating operators, and may provide relevant information on the flavour structure of the underlying fundamental theory., Comment: 17 pages, 5 figures

Most sparticle decay cascades envisaged at the Large Hadron Collider (LHC) involve hadronic decays of intermediate particles. We use state-of-the art techniques based on the \kt jet algorithm to reconstruct the resulting hadronic final states for simulated LHC events in a number of benchmark supersymmetric scenarios. In particular, we show that a general method of selecting preferentially boosted massive particles such as W, Z or Higgs bosons decaying to jets, using sub-jets found by the \kt algorithm, suppresses QCD backgrounds and thereby enhances the observability of signals that would otherwise be indistinct. Consequently, measurements of the supersymmetric mass spectrum at the per-cent level can be obtained from cascades including the hadronic decays of such massive intermediate bosons., Comment: 1+29 pages, 12 figures

In SUSY scenarios with invisible LSP, sparticle masses can be determined from fits to the endpoints of invariant mass distributions. Here we discuss possible improvements by using the shapes of the distributions. Positive results are found for multiple-minima situations and for mass regions where the endpoints do not contain sufficient information to obtain the masses., Comment: to appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 2006

We review the use of invariant mass distributions in cascade decays to measure the masses of New Physics (NP) particles in scenarios where the final NP cascade particle is invisible. We extend earlier work by exploring further the problem of multiple solutions for the masses., Comment: 4 pages, 4 figures, to appear in the proceedings of the XXXIII International Conference on High Energy Physics (ICHEP'06), July 26 - August 2 2006, Moscow

We present a new method to search for a light scalar top (stop), decaying dominantly into $c\tilde\chi^0_1$, at the LHC. The principal idea is to exploit the Majorana nature of the gluino, leading to same-sign top quarks in events of gluino pair production followed by gluino decays into top and stop. We demonstrate the reach of our method in terms of the gluino mass and the stop-neutralino mass difference., Comment: 4 pages, 1 figure, to appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 2006

This is the "TeV4LHC" report of the "Physics Landscapes" Working Group, focused on facilitating the start-up of physics explorations at the LHC by using the experience gained at the Tevatron. We present experimental and theoretical results that can be employed to probe various scenarios for physics beyond the Standard Model., Comment: 222 pp., additional contribution added, typos/layout corrected

We investigate the measurement of supersymmetric particle masses at the LHC in gravitino dark matter (GDM) scenarios where the next-to-lightest supersymmetric partner (NLSP) is the lighter scalar tau, or stau, and is stable on the scale of a detector. Such a massive metastable charged sparticle would have distinctive Time-of-Flight (ToF) and energy-loss ($dE/dx$) signatures. We summarise the documented accuracies expected to be achievable with the ATLAS detector in measurements of the stau mass and its momentum at the LHC. We then use a fast simulation of an LHC detector to demonstrate techniques for reconstructing the cascade decays of supersymmetric particles in GDM scenarios, using a parameterisation of the detector response to staus, taus and jets based on full simulation results. Supersymmetric pair-production events are selected with high redundancy and efficiency, and many valuable measurements can be made starting from stau tracks in the detector. We recalibrate the momenta of taus using transverse-momentum balance, and use kinematic cuts to select combinations of staus, taus, jets and leptons that exhibit peaks in invariant masses that correspond to various heavier sparticle species, with errors often comparable with the jet energy scale uncertainty., Comment: 23 pages, 10 figures, updated to version published in JHEP