Friday, March 7, 2014

Have a safe day!

Friday, March 7

9 a.m.-5:20 p.m.
Lattice QCD Spring Collaboration Meeting - Curia II
Lattice Meets Experiment

3:30 p.m.

4 p.m.
Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Hitoshi Yamamoto, Tohoku University
Title: ILC Status and Prospects

Saturday, March 8

9 a.m.-2 p.m.
Lattice QCD Spring Collaboration Meeting - Curia II
Lattice Meets Experiment

Sunday, March 9

2:30 p.m.
Gallery Chamber Series - WH2XO
Rembrandt Chamber Players
Tickets: $17

Monday, March 10

12:30 p.m.
Particle Astrophysics Seminar (NOTE TIME) - Curia II
Speaker: Timothy Linden, University of Chicago
Title: The Characterization of the Gamma-Ray Signal from the Central Milky Way: A Compelling Case for Annihilating Dark Matter

2 p.m.
Particle Astrophysics Seminar - Curia II
Speaker: Luca Grandi, University of Chicago
Title: DarkSide-50: Performance and Results from the First Atmospheric Argon Run

3:30 p.m.

4 p.m.
All Experimenters' Meeting - Curia II

Click here for NALCAL,
a weekly calendar with links to additional information.

Ongoing and upcoming conferences at Fermilab


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Wilson Hall Cafe

Friday, March 7

- Breakfast: French bistro breakfast
- Breakfast: chorizo and egg burrito
- Chicken cordon bleu sandwich
- Smart cuisine: herb and lemon fish
- Vegetarian eggplant lasagna
- Cuban panino
- Breakfast-for-lunch omelet bar
- New England clam chowder
- Texas-style chili
- Assorted pizza by the slice

Wilson Hall Cafe menu
Chez Leon

Friday, March 7
- French onion soup
- Filet with cabernet sauce
- Potatoes gratin
- Grilled asparagus
- Pear tart

Wednesday, March 12
- Spicy pork diablo
- Sweet potato mash
- Roasted broccoli
- Flourless chocolate ancho cake

Chez Leon menu
Call x3524 to make your reservation.


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Physics in a Nutshell

Certainty about quantum uncertainty

Uncertainty in quantum mechanics is not a fudge factor. Its internal structure yields complex patterns of high and low probability that would not arise from simple measurement error. Seen here are the probability distributions of an electron in an atom.

This is the last article in a series about quantum mechanics. Previously, I talked about how quantities can be multivalued yet restricted to whole numbers, like a light switch that is both on and off; how quantum processes can include acausal influences, like a time traveler who gets his time machine by going back and giving it to himself; and how so-called particle waves are neither waves nor particles. These are such dubious claims that I was tempted to crowd the exposition with descriptions of experiments, but instead of confusing the issue, I left the "how we know" for this article.

There are several objections one could make to my presentation. Though I said that a quantum light switch is both on and off, measurements will find it either on or off, not both. The time loops of quantum processes are similarly hidden behind a veil of indeterminacy. It might seem like all of these quantum effects are just speculations about what's happening inside the noise of an uncertain measurement, but there's more to it than that.

The key ingredient is an effect known as interference. The probability of finding a multivalued quantity as one value rather than another is the square of a more fundamental description called the wavefunction. Squaring a number hides information: 25 is the square of 5, but it is also the square of −5. Since we can only measure probabilities, we can't determine the sign of a wavefunction, but if two wavefunctions overlap, or "interfere," we can discover a difference in their signs. For example, if one has magnitude 5 and the other has magnitude 3, the square of 5 + 3 (or −5 + −3) is 64, but the square of −5 + 3 (or 5 + −3) is 4. When you introduce a second wavefunction, the resulting probability can sometimes decrease.

Probabilities, on the other hand, only increase when you combine them. My chances of winning the lottery would be almost doubled if I had twice as many tickets. Most experiments that distinguish quantum multivaluedness from mere uncertainty exploit this distinction. Wavefunctions describing a particle's spread in position have alternating peaks and troughs of high and low probability, whereas measurement error in the same circumstances would yield a smeared-out blob.

Physicists were so uncomfortable with the idea of acausal influence that they considered countless alternatives to quantum mechanics, cleverly accounting for the apparent acausality with complicated mechanisms. In 1964, John Bell used an interference effect to pose a numerical test that distinguishes quantum mechanics from all causal mechanisms based on a few weak assumptions. This test was experimentally performed in 1981 by Aspect and Grangier and is repeated often under different circumstances with weaker sets of assumptions. The results have always favored the quantum explanation.

Studying quantum mechanics is like a conversation with an alien race. Our prior experience and even brain evolution have not prepared us for this conversation, but if we can stretch our minds around what the data are telling us, we'll never see the world the same way again.

Jim Pivarski

Image of the Day

The particle physicist according to 8th graders

After viewing the documentary "Fermilab: Science at Work," Hinsdale Middle School 8th graders created this word cloud composed of descriptions of particle physicists. Kelly Sledz teaches the class.
Special Announcement

Daylight saving time begins Sunday - set your clocks, change your batteries

It's time to spring forward! Daylight saving time begins this Sunday at 2 a.m. Be sure to set your clocks ahead one hour Saturday night before going to bed. The shift to daylight saving time also serves as a reminder to install new batteries in smoke detectors, flashlights, carbon monoxide detectors and hazard warning radios.

In the News

A movie about the Large Hadron Collider that you'll actually understand

From Wired, March 4, 2014

Most people have heard of the Large Hadron Collider. However, most people also don't understand exactly how it works or what it does. (Something with physics, maybe?) Scientists at the European Organization for Nuclear Research (CERN), where the LHC is located, discovered the famed Higgs boson — aka the "God particle" — in 2012 after years of experiments, but truly understanding what that means for science is a bit murky.

Enter "Particle Fever." The new documentary [opened March 5] in New York, and aims to demystify the years of LHC research that led to the discovery of the Higgs boson particle — as well as make it exciting for audiences to watch.

Read more

In the News

Black hole winds stronger than expected

From Physics World, Feb. 28, 2014

Black holes release more energy into their host galaxies than previously thought, according to an international team of researchers. The team observed a microquasar in the galaxy M83 and found that the outgoing kinetic power of the object was more than predicted for a black hole of that mass. Their finding should help improve models of how black holes evolve over time, as well as improve our understanding of the effects of black holes on gas in the early universe.

Read more

Frontier Science Result:
Theory Group

New theories for new physics

The Standard Model of particle physics can be summarized on a coffee mug. Theorists predict where cracks in this framework may start showing up. Image courtesy of Quantum Diaries

Scientists use data from the Large Hadron Collider to measure the properties of the Standard Model at higher energies than ever before. While this allows us to confirm that our theory of the world works as expected in a new regime, everyone involved really hopes to see this theory break.

Discovering new particles or new principles is the aim of these large experiments. To do so requires not only knowing the predictions of the Standard Model very well and measuring the outcome of collisions very precisely, but also understanding the ways that deviations are likely to show up and which observables can probe them. This is the focus of theorists that work on physics beyond the Standard Model.

The recent discovery of the Higgs boson has completed the Standard Model on the one hand, but it has given us a new opportunity to search for Beyond the Standard Model physics on the other. The Standard Model framework makes exact predictions for the properties of the Higgs. Any observed deviation from these predictions would signal a breaking of this framework and indicate the existence new physics. The nature and size of such a deviation would give important clues as to the nature and scale of new particles.

One possibility not allowed in the Standard Model is that the interactions of the Higgs boson would violate a particle property called flavor. This would mean, for example, that a Higgs boson could simultaneously interact with two particles of different families, perhaps decaying into a muon and a positron. (The stronger the interaction, the more likely it is for these particles either to form or decay from a Higgs and the greater its so-called coupling constant.)

Current and former members of Fermilab's Theory Group have explored the limits on and future opportunities to discover such interactions both at the LHC and with low-energy tests. One such opportunity would arrive with the start of the upcoming Mu2e experiment at Fermilab. We have found that Mu2e would be able to probe Higgs decays into a muon and an electron with an extremely small interaction strength, one with a coupling constant of 10-6 or 10-7. This coupling strength is even weaker than the weakest interaction of the Higgs in the Standard Model.

Furthermore, the LHC experiments can search for Higgs decays into a muon and a tau and be sensitive to the corresponding Higgs interaction at the 10-2 level. Motivated by the work of these Fermilab theorists, LHC scientists are currently conducting these searches for these decays.

We all hope that the Higgs is just the beginning of the new discoveries at the LHC and that we will see the Standard Model break in numerous ways. There are strong reasons to believe that the Standard Model is not the final answer. But how Beyond the Standard Model theory completes the Standard Model is unknown. The Fermilab Theory Group is actively researching many ideas, such as supersymmetry, extra dimensions and strongly coupled theories, but space does not permit the discussion of them all. For those who wish to learn more or have evidence of the Standard Model breaking, please stop by the third floor of Wilson Hall!

Patrick Fox and Roni Harnik

In Brief

Today at 11 a.m. - Fermilab's Brian Nord joins DOE Twitter Lab Chat on dark energy

Scientist Brian Nord will join today's Department of Energy lab chat on dark energy. Photo: Reidar Hahn

Today at 11 a.m. Central time, the Department of Energy will host a Twitter discussion on dark energy. Joining the chat is Fermilab's Brian Nord, a scientist on the Dark Energy Survey and main writer for Dark Energy Detectives. Also participating are Berkeley Lab's Eric Linder, an expert on dark energy and the accelerating universe, and SLAC's Eduardo Rozo, an astrophysicist on the Dark Energy Survey.

Submit your questions to @energy using the hashtag #labchat, leave a comment on, or send an email to


Today's New Announcements

Barn Dance - March 9

Rembrandt Chamber Players - Gallery Chamber Series - March 9

Budker Seminar - March 10

Employee Appreciation Day massages

Society of Philosophy Club meets March 13

URA Thesis Award competition deadline - March 20

Photography contest - through March 21

2014 FRA Scholarship applications due April 1

Portions of west atrium stair closed for construction

Help Abri Credit Union celebrate our members and Pi Day

International folk dancing meets Thursday evenings at Kuhn Barn

Scottish country dancing meets Tuesday evenings at Kuhn Barn

English country dancing at Kuhn Village Barn

Indoor soccer

Find new classified ads on Fermilab Today.