Monitoring the CMS strip tracker readout system

The CMS Silicon Strip Tracker at the LHC comprises a sensitive area of approximately 200 m2 and 10 million readout channels. Its data acquisition system is based around a custom analogue front-end chip. Both the control and the readout of the front-end electronics are performed by off-detector VME boards in the counting room, which digitise the raw event data and perform zero-suppression and formatting. The data acquisition system uses the CMS online software framework to configure, control and monitor the hardware components and steer the data acquisition. The first data analysis is performed online within the official CMS reconstruction framework, which provides many services, such as distributed analysis, access to geometry and conditions data, and a Data Quality Monitoring tool based on the online physics reconstruction. The data acquisition monitoring of the Strip Tracker uses both the data acquisition and the reconstruction software frameworks in order to provide real-time feedback to shifters on the operational state of the detector, archiving for later analysis and possibly trigger automatic recovery actions in case of errors. Here we review the proposed architecture of the monitoring system and we describe its software components, which are already in place, the various monitoring streams available, and our experiences of operating and monitoring a large-scale system

The CMS Tracker Readout Front End Driver

The Front End Driver, FED, is a 9U 400mm VME64x card designed for reading out the Compact Muon Solenoid, CMS, silicon tracker signals transmitted by the APV25 analogue pipeline Application Specific Integrated Circuits. The FED receives the signals via 96 optical fibers at a total input rate of 3.4 GB/sec. The signals are digitized and processed by applying algorithms for pedestal and common mode noise subtraction. Algorithms that search for clusters of hits are used to further reduce the input rate. Only the cluster data along with trigger information of the event are transmitted to the CMS data acquisition system using the S-LINK64 protocol at a maximum rate of 400 MB/sec. All data processing algorithms on the FED are executed in large on-board Field Programmable Gate Arrays. Results on the design, performance, testing and quality control of the FED are presented and discussed

Preheating, Supersymmetry Breaking and Baryogenesis

Fluctuations of scalar fields produced at the stage of preheating after inflation are so large that they can break supersymmetry much stronger than inflation itself. These fluctuations may lead to symmetry restoration along flat directions of the effective potential even in the theories where the usual high temperature corrections are exponentially suppressed. Our results show that nonthermal phase transitions after preheating may play a crucial role in the generation of the primordial baryon asymmetry by the Affleck-Dine mechanism. In particular, the baryon asymmetry may be generated at the very early stage of the evolution of the Universe, at the preheating era, and not when the Hubble parameter becomes of order the gravitino mass.Comment: 4 pages, no figure

On the Moduli Problem and Baryogenesis in Gauge-mediated SUSY Breaking Models

We investigate whether the Affleck-Dine mechanism can produce sufficient baryon number of the universe in the gauge-mediated SUSY breaking models, while evading the cosmological moduli problem by late-time entropy production. We find that the Q-ball formation renders the scenario very difficult to work, irrespective of the detail mechanism of the entropy production.Comment: 11 pages, RevTeX, 5 postscript figures include

Cosmology with a TeV mass GUT Higgs

The most natural way to break the GUT gauge symmetry is with a Higgs field whose vacuum expectation value is of order 10^{16}\,\mbox{GeV} but whose mass is of order $10^2$ to 10^3\,\mbox{GeV}. This can lead to a cosmological history radically different from what is usually assumed to have occurred between the standard inflationary and nucleosynthesis epochs, which may solve the gravitino and Polonyi/moduli problems in a natural way.Comment: 4 pages, revte

Supersymmetric D-term Inflation, Reheating and Affleck-Dine Baryogenesis

The phenomenology of supersymmetric models of inflation, where the inflationary vacuum energy is dominated by D-terms of a U(1), is investigated. Particular attention is paid to the questions of how to arrange for sufficient e-folds of inflation to occur, what kind of thermal history is expected after the end of inflation, and how to implement successful baryogenesis. Such models are argued to require a more restrictive symmetry structure than previously thought. In particular, it is non-trivial that the decays of the fields driving D-inflation can reheat the universe in such a way as to avoid the strong gravitino production constraints. We also show how the initial conditions for Affleck-Dine baryogenesis can arise in these models and that the simplest flat directions along which baryon number is generated can often be ruled out by the constraints coming from decoherence of the condensate in a hot environment. At the end, we find that successful reheating and baryogenesis can take place in a large subset of D-inflationary models.Comment: 23 pages LaTe

Naturally Large Cosmological Neutrino Asymmetries in the MSSM

A large neutrino asymmetry is an interesting possibility for cosmology, which can have significant observable consequences for nucleosynthesis and the cosmic microwave background. However, although it is a possibility, there is no obvious reason to expect the neutrino asymmetry to be observably large. Here we note that if the baryon asymmetry originates via the Affleck-Dine mechanism along a d=4 flat direction of the MSSM scalar potential and if the lepton asymmetry originates via Affleck-Dine leptogenesis along a d=6 direction, corresponding to the lowest dimension directions conserving R-parity, then the ratio n_{L}/n_{B} is naturally in the range 10^{8}-10^{9}. As a result, a potentially observable neutrino asymmetry is correlated with a baryon asymmetry of the order of 10^{-10}.Comment: 10 pages LaTeX. Final version to be published in Physical Review Letter

Thermal Inflation and the Moduli Problem

In supersymmetric theories a field can develop a vacuum expectation value $M \gg 10^3\,{\rm GeV}$, even though its mass $m$ is of order $10^2$ to $10^3\,{\rm GeV}$. The finite temperature in the early Universe can hold such a field at zero, corresponding to a false vacuum with energy density $V_0 \sim m^2 M^2$. When the temperature falls below $V_0^{1/4}$, the thermal energy density becomes negligible and an era of thermal inflation begins. It ends when the field rolls away from zero at a temperature of order $m$, corresponding to of order 10 $e$-folds of inflation which does not affect the density perturbation generated during ordinary inflation. Thermal inflation can solve the Polonyi/moduli problem if $M$ is within one or two orders of magnitude of $10^{12}\,{\rm GeV}$.Comment: Revised version to appear in Phys Rev D. Improved discussion of the possible effect of parametric resonance. Latex, 31 page

Lorentz Invariance and the Cosmological Constant

Non-trivial solutions in string field theory may lead to the spontaneous breaking of Lorentz invariance and to new tensor-matter interactions. It is argued that requiring the contribution of the vacuum expectation values of Lorentz tensors to account for the vacuum energy up to the level that $\Omega_{0}^{\Lambda} = 0.5$ implies the new interactions range is $\lambda \sim 10^{-4} m$. These conjectured violations of the Lorentz symmetry are consistent with the most stringent experimental limits.Comment: 13 pages, plain Latex. This essay was selected for an honorable mention in the 1997 Gravity Research Foundation essay competio

Cosmological Implications of Dynamical Supersymmetry Breaking

We provide a taxonomy of dynamical supersymmetry breaking theories, and discuss the cosmological implications of the various types of models. Models in which supersymmetry breaking is produced by chiral superfields which only have interactions of gravitational strength (\eg\ string theory moduli) are inconsistent with standard big bang nucleosynthesis unless the gravitino mass is greater than \CO(3) \times 10^4 GeV. This problem cannot be solved by inflation. Models in which supersymmetry is dynamically broken by renormalizable interactions in flat space have no such cosmological problems. Supersymmetry can be broken either in a hidden or the visible sector. However hidden sector models suffer from several naturalness problems and have difficulties in producing an acceptably large gluino mass.Comment: 24 pages (uses harvmac) UCSD/PTH 93-26, RU-3