I will be attending next week to a conference in Split (Croatia). The conference is titled "LHC Days", and has the purpose of bringing together experimental physicists working at the main CERN experiments with theorists and experimentalists from all over the world, to discuss the current status and the future perspectives of research in particle physics, focusing of course on the Large Hadron Collider at CERN.
I have been assigned a talk titled "Top Physics at the Tevatron", and I will therefore represent the CDF and DZERO collaborations and describe their results. It will be very interesting for me to inform my CMS colleagues about the newest experimental techniques in use at the Tevatron to measure the properties of the top quark in hadronic collisions.
As soon as I find some time, I will publish here a few of the slides of my talk, trying to explain them in simple terms. For the time being, let me just paste here the draft of one slide I consider important and of general interest: an explanation of why the top quark mass, now known with 0.67% accuracy thanks to the huge effort of the two experiments, may still provide additional crucial information on the fundamental theory of subatomic particles if its uncertainty is further reduced in the next few years.
In a nutshell, the slide makes a few points about the importance of a precise measurement of the top mass. The simple-minded argument that the top mass is a decisive input in electroweak fits to Standard Model (SM) observables when the aim is a prediction of the unknown mass of the Higgs boson fails nowadays, since the top quark is already known with enough accuracy for that purpose, as compared to other SM parameters. You can observe it in the top right graph, where the horizontal axis describes the unknown Higgs boson mass, and the vertical axis the top quark mass. The blue oblong region is the area where the two parameters are bound to lay if we believe the measurement of all other electroweak observables. The green region instead includes in the fit the known value of the top mass, which is also shown as a light green horizontal band.
As you can see, the inclusion of the top mass strongly constrains the allowed values of the top mass, precisely to lay within the two oval green regions. Note that the LEP II lower bound on the Higgs mass and the Tevatron excluded window between 156 and 173 GeV (shown in grey) significantly help reduce the extent of those regions (which would otherwise include the pink areas). Now, ask yourself the question: if we shrunk the top mass band to a narrow horizontal line, how much would the green areas shrink consequently ? The answer is, minimally! So a more precise top quark mass is not needed if all we want is to improve our indirect knowledge of the Higgs boson's mass.
It turns out, however, that other EW parameters in the SM are still benefitting a lot from an increased precision in the mass of the top quark. This is shown in the figure on the lower right (which comes from a highly interesting, if not very recent, paper by S.Heinemeyer et al., hep-ph/0306181) which however is a bit too complicated for me to explain meaningfully in a few lines. Suffices to say that both for the Standard Model, and for most of the Beyond-the-Standard-Model scenarios, a better-known top mass remains highly desirable to this day!
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Top Secret: On Confidentiality On Scientific Issues, Across The Ring And Across The Bedroom
- Drug Prevents Key Age-related Brain Change In Rats
- Would New Planet X Clear Its Orbit? - And Any Better Name Than "Planet Nine"?
- A New Alternative To Sodium: Fish Sauce
- Smoking Bans Reduce Risk Of Cardiovascular Disease In Non-Smokers
- Naomi Oreskes And Denialism About The Scientific Consensus On GMOs And Nuclear Energy
- A Conservative Argument For Genetic Modification Of Embryos
- "So there is no why like Bob Fletcher or as some people say you can already see it on Russian news..."
- "Hi Joe, yes the thing is - all that is fine, it's logical from your point of view. And whatever..."
- " Like I asked David Brin: Who are the ones who are actually insane? Certainly it is NOT the skeptics..."
- "https://www.youtube.com/watch?v=nVyV4L072jY So then what is going on in this video? Also what is..."
- "Just curious, When was the last time you (the author) generated a mathematical model? On what?..."
- Florida Declares Zika Virus State of Emergency
- Indonesia’s Many Human Physical Deformities: A Closer Look
- Spinal ‘Column’: Love for Hunchback Dog, Breakthrough for 8-Yr-Old Girl
- BMI is Bologna
- Energy Drinks: The Dose Makes the Poison
- California’s Prop 65: Bad For Public Acceptance Of Science, About To Get Worse
- Cambridge researcher develops smartphone app to map Swiss-German dialects
- Studies link healthy workforces to positive stock market performance
- Pioneering discovery leads to potential preventive treatment for sudden cardiac death
- Online shopping might not be as green as we thought
- Gene family turns cancer cells into aggressive stem cells that keep growing