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In this issue:
P5 Meets at SLAC
Science Today: Theory Group - Interpreting LHC Data
symmetry: 24/7 - Labs That Never Sleep

SLAC Today

Thursday - April 20, 2006

(Image - P5)

P5 Meets at SLAC

Today and tomorrow, the Particle Physics Project Prioritization Panel (P5) subpanel meets at SLAC. P5's overall charge is to propose a detailed roadmap for U.S. high-energy physics over the next decade.

"In science, we must earn funding support through pursuit of the most outstanding research opportunities, which demands that we lay out a vision for the future that is compelling and well articulated," said Persis Drell, Director of the Particle and Particle Astrophysics Directorate.  "In developing our vision, we as a community must make the difficult choices so that we focus on only the most exciting and transformational experimental opportunities.  P5 is being charged to develop a detailed roadmap for the field and set priorities.  I believe it is vital to support the panel in putting together a long-term vision for the field."

The meeting at SLAC will be used to examine the future research and development on the International Linear Collider and opportunities in dark energy science, such as LSST and SNAP, as well as revisiting the operating of the B Factory in 2008.  A visit earlier in the week to Fermilab allowed the panel to review opportunities in neutrino physics, including EXO, and dark matter searches.  P5 will submit a final report to the Department of Energy and National Science Foundation by September 2006.

Tonight between 6:20 and 7:15 pm, P5 will hold a reception and informal community discussion outside the ROB (Building 48). The full meeting agenda is available online.

(Daily Column - Science Today)

Theory Group: Interpreting LHC Data

It is unlikely that there is a single high-energy physicist in the world who is not eagerly awaiting the first results from the Large Hadron Collider (LHC). The LHC will hopefully shed light on the origin of electroweak symmetry breaking and might lead to the discovery of new physics.

However, in order to interpret the LHC data correctly, it is very important to understand expected backgrounds and signals within and beyond the Standard Model. Otherwise, interpreting LHC data would be worse than looking for a needle in a haystack.

It is particularly important to compute the rates of Standard Model processes with large numbers of final quarks and gluons, since new physics appears as excesses in very energetic events. But carrying out theoretical computations becomes quite difficult as the number of final particles increases.

Scattering amplitudes are calculated with Feynman diagrams, as an expansion in the quark-gluon interaction. However, this is not an effective way to get the answer. The number of diagrams that must be computed grows extremely quickly with the number of external particles (legs) and the number of loops. Direct analytical methods fail already at one loop with more than only five external legs. But the results of these computations are a lot less complex than the expressions at intermediate stages. This suggests that we need to look for computational methods which reflect the relative underlying simplicity of the results. Read more...

symmetry - 24/7: Labs That Never Sleep

By Dawn Stanton

(Photo - Fermilab's Tevatron)

Fermilab's Tevatron

Here they measure the time not in minutes or hours. Instead they think in terms of how many antiprotons are ready to stack and how soon the Tevatron will be ready to accept new beam. Or how fast they need to fix something, any time of the day or night. Or how long they can stay awake.

The scenes are played out around the clock and around the world in control rooms at CERN in Switzerland; at DESY in Germany; at KEK in Japan; at SLAC in California; and accelerators at many other research institutions. These 24 hours at Fermilab provide a glimpse of the work taking place at these labs.

High-energy particle physics is a lifestyle where the mundane and the marvelous meet. When everything's working well, particles and antiparticles accelerate to near the speed of light and make collisions that produce spectacular energy events. Discoveries that revolutionize human understanding of the subatomic world can happen, as discovery of the top and bottom quarks did, in 1995 and 1977, respectively.

When people and machines run 24 hours a day, seven days a week, a lot of the mundane is needed to produce the marvelous.  Read more...


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