D. M. Newbold

This document a outlines a set of simplified models for dark matter and its interactions with Standard Model particles. It is intended to summarize the main characteristics that these simplified models have when applied to dark matter searches at the LHC, and to provide a number of useful expressions for reference. The list of models includes both s-channel and t-channel scenarios. For s-channel, spin-0 and spin-1 mediations are discussed, and also realizations where the Higgs particle provides a portal between the dark and visible sectors. The guiding principles underpinning the proposed simplified models are spelled out, and some suggestions for implementation are presented.

In this White Paper we present and discuss a concrete proposal for the consistent interpretation of Dark Matter searches at colliders and in direct detection experiments. Based on a specific implementation of simplified models of vector and axial-vector mediator exchanges, this proposal demonstrates how the two search strategies can be compared on an equal footing.

Forthcoming hardware upgrades to the CMS experiment trigger and readout system are based upon the ATCA or μTCA bus standards, giving them the opportunity to be controlled via commodity gigabit Ethernet. These hardware upgrades supersede existing systems largely based upon the VME-bus standard, and thus a requirement has arisen to provide a new low-level control infrastructure for use by trigger and readout subsystem developers. This paper details the recent research and development into a tightly-integrated suite of software and firmware based upon the IPbus protocol that allows such Ethernet-attached hardware to be controlled in an efficient and highly-scalable manner.

We report on a high statistics search for the ${\ensuremath{\Xi}}^{\ensuremath{-}\ensuremath{-}}(1860)$ resonance in ${\ensuremath{\Sigma}}^{\ensuremath{-}}$-nucleus collisions at $340\phantom{\rule{0.3em}{0ex}}\mathrm{GeV}∕c$. No evidence for this resonance is found in our data sample which contains 676000 ${\ensuremath{\Xi}}^{\ensuremath{-}}$ candidates above background. For the decay channel ${\ensuremath{\Xi}}^{\ensuremath{-}\ensuremath{-}}(1860)\ensuremath{\rightarrow}{\ensuremath{\Xi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}$ and the kinematic range $0.15<{x}_{F}<0.9$ we find a $3\ensuremath{\sigma}$ upper limit for the production cross section of 3.1 and $3.5\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{b}$ per nucleon for reactions with carbon and copper, respectively.

A novel approach to first-level hardware triggering in the LHC experiments has been studied and a prototype system built. Calorimeter trigger primitive data ( ∼ 5 Tb/s) are re-organised and time-multiplexed so that a single processing node (FPGA) may access the data corresponding to the entire detector for a given bunch crossing. This provides maximal flexibility in the construction of new trigger algorithms, which will be an important factor in ensuring adequate trigger performance at the very high levels of background expected at the upgraded LHC.

When the LHC resumes operation in 2015, the higher centre-of-mass energy and high-luminosity conditions will require significantly more sophisticated algorithms to select interesting physics events within the readout bandwidth limitations. The planned upgrade to the CMS calorimeter trigger will achieve this goal by implementing a flexible system based on the μTCA standard, with modules based on Xilinx Virtex-7 FPGAs and up to 144 optical links running at speeds of 10 Gbps. The upgrade will improve the energy and position resolution of physics objects, enable much improved isolation criteria to be applied to electron and tau objects and facilitate pile-up subtraction to mitigate the effect of the increased number of interactions occurring in each bunch crossing. The design of the upgraded system is summarised with particular emphasis placed on the results of prototype testing and the experience gained which is of general application to the design of such systems.

We report on a high-statistics search for the Θ(1540)+ resonance in Σ−-nucleus collisions at 340 GeV/c. No evidence for this resonance was found in our data sample which contains 13 million Ks0→π+π− decays above background. For the decay channel Θ+→Ks0p and the kinematic range xF> 0.05, we find the production cross section to be BR(Θ+→Ks0p)σ0<1.8 μb per nucleon at 99% C.L.Received 26 July 2005DOI:https://doi.org/10.1103/PhysRevC.72.055201©2005 American Physical Society

The CMS experiment is currently developing a computing system capable of serving, processing and archiving the large number of events that will be generated when the CMS detector starts taking data. During 2004 CMS undertook a large scale data challenge to demonstrate the ability of the CMS computing system to cope with a sustained data-taking rate equivalent to 25% of startup rate. Its goals were: to run CMS event reconstruction at CERN for a sustained period at 25 Hz input rate; to distribute the data to several regional centers; and enable data access at those centers for analysis. Grid middleware was utilized to help complete all aspects of the challenge. To continue to provide scalable access from anywhere in the world to the data, CMS is developing a layer of software that uses Grid tools to gain access to data and resources, and that aims to provide physicists with a user friendly interface for submitting their analysis jobs. This paper describes the data challenge experience with Grid infrastructure and the current development of the CMS analysis system.

The hyperon beam experiment WA89 at CERN uses the upgraded Omega RICH detector for identification of π, K and p/p̄ from Σ−-N reactions. Cherenkov photons from a 5 m long nitrogen radiator are detected in drift chambers with TMAE-loaded ethane. Recent results on the performance of the detector are presented.

The Omega RICH, a large-aperture detector for identification of secondary pions, kaons, and (anti) protons was in operation at the CERN Omega spectrometer facility between 1984 and 1994. Cherenkov photons from a 5 m long radiator were detected in drift chambers with quartz windows, using TMAE-loaded counting gases. The RICH was used by experiments WA69 and WA82, until 1988. It was then equipped with new drift chambers and mirrors and was in use since 1990 in experiments WA89 and WA94. The setup in the WA89 hyperon beam experiment is described in more detail and efficiencies, resolutions, and physics results are discussed.

Abstract The DUNE neutrino experiment far detector has a fiducial mass of 40 kt. The O(1M) readout channels are distributed over the four 10 kt modules and need to be synchronized with respect to each other to a precision of O(10 ns). The entire system needs to be synchronized with respect to GPS time to O(100 ns). The system needs to be reliable, simple and affordable. Clock and synchronization information are encoded on the same fibre using a protocol based on duty cycle shift keying (DCSK) with 8b10b encoding to ensure DC-balance. The use of DCSK allows the clock to be recovered directly by PLL based clock generators without needing to use a separate clock and data recovery (CDR) device. Small scale tests show a timing jitter at the endpoint of ≈10 ps with respect to the timing master.

A demonstrator for the CMS Level-1 calorimeter trigger system has been designed, manufactured, tested and a time-multiplexed trigger implemented. The prototype card uses the AMC double width form factor, 5Gb/s links and a Xilinx XC5VTX150T or XC5VTX240T FPGA. A possible implementation of such a trigger architecture in CMS is described.

As the LHC increases luminosity and energy, it will become increasingly difficult to select interesting physics events and remain within the readout bandwidth limitations. An upgrade to the CMS Calorimeter Trigger implementing more complex algorithms is proposed. It utilizes AMC cards with Xilinx FPGAs running in microTCA crate with card interconnections via crate backplanes and optical links operating at up to 10 Gbps. Prototype cards with Virtex-6 and Virtex-7 FPGAs have been built and software frameworks for operation and monitoring developed. The physics goals, hardware architectures, and software will be described in this talk. More details can be found in a separate poster at this conference.

The CMS Binary Chip is an ASIC designed for the readout of silicon strip sensors. Tests have been performed to verify that it operates correctly over a range of temperatures from −40°C – 40°C. The results of these tests are presented.

Tests of a prototype for the electromagnetic calorimeter (ECAL) of the compact muon solenoid experiment (CMS) at the large hadron collider are described. The basic unit for the endcap ECAL in CMS is a “supercrystal” of 25 lead tungstate crystals. Results are presented from tests of the first full-sized supercrystal in electron beams and in a 3 T magnetic field. The supercrystal was exposed to electron beams with energies from 25 to 180 GeV. An energy resolution (σE/E) of (0.48±0.01)% was measured at 180 GeV.

We report on the observation of a KSp resonance signal at a mass of 1765 ± 5 MeV/c 2, with intrinsic width Γ = 108 ± 22 MeV/c 2, produced inclusively in Σ--nucleus interactions at 340 GeV/c in the hyperon beam experiment WA89 at CERN. The signal was observed in the kinematic region xF>0.7, in this region its production cross section rises approximately linearly with (1-xF), reaching BR(X→KSp)dσ/dxF=(5.2±2.3)μb per nucleon at xF=0.8. The hard xF spectrum suggests the presence of a strong leading particle effect in the production and hence the identification as a Σ*+ state. No corresponding peaks were observed in the K-p and Λπ± mass spectra.

We have measured the production of strange baryons and antibaryons in 340-GeV/c Σ−+C and 260-GeV/c n+C interactions. The single xF distributions show the expected leading particle effect, and the single p2t distributions show a distinct nonthermal behavior. The xF distributions of Λ-Λ pairs indicate two different phase space distributions for the two coincident baryons. On the other hand two ¯Λ’s show identical distributions. Momentum conservation during the formation process may represent a significant source for the observed behavior.Received 21 September 2001DOI:https://doi.org/10.1103/PhysRevC.65.042202©2002 American Physical Society

The CMS 2004 Data Challenge (DC04) was devised to test several key aspects of the CMS Computing Model in three ways: by trying to sustain a 25 Hz reconstruction rate at the Tier-0; by distributing the reconstructed data to six Tier-1 Regional Centres (CNAF in Italy, FNAL in US, GridKA in Germany, IN2P3 in France, PIC in Spain, RAL in UK) and handling catalogue issues; by granting data accessibility at remote centres for analysis. Simulated events, up to the digitization step, were produced prior to the DC as input for the reconstruction in the Pre-Challenge Production (PCP04). In this paper, the model of the Tier-0 implementation used in DC04 is described, as well as the experience gained in using the newly developed data distribution management layer, which allowed CMS to successfully direct the distribution of data from Tier-0 to Tier-1 sites by loosely integrating a number of available Grid components. While developing and testing this system, CMS explored the overall functionality and limits of each component, in any of the different implementations that were deployed within DC04. The role of Tier-1's is presented and discussed, from the import of reconstructed data from Tier-0, to the archiving on to the local Mass Storage System (MSS) and the data distribution management to Tier-2's for analysis. Participating Tier-1's differed in available resources, setup and configuration. A critical evaluation of the results and performances achieved adopting different strategies in the organization and management of each Tier-1 centre to support CMS DC04 is presented.

The Compact Muon Solenoid (CMS) experiment is currently installing upgrades to their Calorimeter Trigger for LHC Run 2 to ensure that the trigger thresholds can stay low, and physics data collection will not be compromised. The electronics will be upgraded in two stages. Stage-1 for 2015 will upgrade some electronics and links from copper to optical in the existing calorimeter trigger so that the algorithms can be improved and we do not lose valuable data before stage-2 can be fully installed by 2016. Stage-2 will fully replace the calorimeter trigger at CMS with a micro-TCA and optical link system. It requires that the updates to the calorimeter back-ends, the source of the trigger primitives, be completed. The new system's boards will utilize Xilinx Virtex-7 FPGAs and have hundreds of high-speed links operating at up to 10 Gbps to maximize data throughput. The integration, commissioning, and installation of stage-1 in 2015 will be described, as well as the integration and parallel installation of the stage-2 in 2015, for a fully upgraded CMS calorimeter trigger in operation by 2016.

A new tracking detector is under development for use by the CMS experiment at the High-Luminosity LHC (HL-LHC).A crucial component of this upgrade will be the ability to reconstruct within a few microseconds all charged particle tracks with transverse momentum above 3 GeV, so they can be used in the Level-1 trigger decision.A concept for an FPGA-based track finder using a fully time-multiplexed architecture is presented, where track candidates are reconstructed using a projective binning algorithm based on the Hough Transform followed by a track fitting based on the linear regression technique.A hardware demonstrator using MP7 processing boards has been assembled to prove the entire system, from the output of the tracker readout boards to the reconstruction of tracks with fitted helix parameters.It successfully operates on one eighth of the tracker solid angle at a time, processing events taken at 40 MHz, each with up to 200 superimposed proton-proton interactions, whilst satisfying latency constraints.The demonstrated track-reconstruction system, the chosen architecture, the achievements to date and future options for such a system will be discussed.

In the 17th century Sir Isaac Newton wrote ``These are therefore the Agents in Nature able to make the Particles of Bodies ftick together by very ftrong Attractions, And it is the Bufinefs of Experimatal Philofophy to find them out''. In the $21st century the Large Hadron Collider (LHC) continues that ``business''. Bunches of protons will be accelerated to an energy of 7TeV/c per proton around a 27km circumference ring buried underneath French/Swiss countryside near Geneva. At a number of points around the ring counter-rotating bunches of protons will be passed through each other. Some of the protons will interact violently and the new particles generated will fly outwards into detectors surrounding the interaction region. Typically these detectors have millions of channels and data flows out of the ``front-end'' at about 400EBytes/year. Data can only be stored at about 1PByte/year, a factor of 4x10^5 less. Fortunately most interactions involve physical processes that are already understood and a multi-level trigger system is used to select data from interesting or unexpected events. This paper describes the Global Calorimeter Trigger (GCT), part of the trigger system for the Compact Muon Solenoid (CMS) detector at the LHC.