A Week of Interactions - March 7th, 2017
Fermilab Results Change Higgs Mass Estimate
8 June 2004
Fermi National Accelerator Laboratory
04-08
June 9, 2004
For immediate release
Press Contact:
Kurt Riesselmann, Public Affairs, Fermilab, 630-840-3351
Photos and background information available at:
www.fnal.gov/pub/presspass/press_releases/dzero_topquark/
Batavia, Ill.-Scientists at the Department of Energy's Fermi National
Accelerator Laboratory today (June 9) announced new results that change
the best estimate of the mass of the postulated Higgs boson from
approximately 96 GeV/c^2 to 117 GeV/c^2. Compared to the previous
result, the new value is in better agreement with direct searches - such
as those conducted by CERN experiments - that excluded a mass below 114
GeV/c^2. In a paper to appear in the June 10 issue of Nature magazine,
physicists of Fermilab's DZero experiment report on results obtained by
applying a new analysis technique to data obtained from 1992 to 1996
during Collider Run I at the Fermilab Tevatron, the world's
highest-energy particle accelerator.
"These important results demonstrate how our scientists are applying new
techniques to existing data, producing new estimates for the mass of the
Higgs boson," said Dr. Raymond L. Orbach, Director of the Department of
Energy's Office of Science, which funds Fermilab. "We eagerly await the
next round of results from the vast quantities of data that are
generated today at the Fermilab Tevatron."
Particle physicists predict the existence of a heavy particle, the Higgs
boson, which interacts with particles of matter to give them their
characteristic masses. However, despite attempts at particle accelerator
experiments to observe the Higgs, no one has yet detected its existence.
While scientists have never observed the Higgs itself, they can predict
its mass and other characteristics by making precise observations of
known particles with which it presumably interacts. In particular, the
masses of the top quark, discovered at Fermilab in 1995, and the W boson
together constrain the mass of the Higgs. A precise measurement of the
top quark mass not only lets experimenters home in on the energy level
of particle collisions required to produce a Higgs, but also reveals
whether the boson's existence is consistent with experimental data. The
indirect indication of the Higgs mass guides particle physicists in
their ongoing hunt for direct observation and confirmation of the
particle's existence.
Scientists from nearly 40 U.S. universities and 40 foreign institutions
contributed to this measurement. The DZero paper employs a novel
technique for data analysis, based on ideas first developed in the 1980s
by physicist Kunitaka Kondo of Japan's Waseda University, a collaborator
on Fermilab's CDF experiment, and independently by Richard Dalitz and
Gary Goldstein at Oxford.
"This analysis technique allows us to extract more information from each
top-quark event that occurred in our detector," said DZero
cospokesperson John Womersley. "The result yields a greatly improved
precision, of 5.3 GeV/c^2, in the DZero top mass measurement. The new
measurement is comparable to the precision of all previous top quark
mass measurements put together. When this new result is combined with
all other measurements from both the DZero and CDF experiments, the new
world average for the top mass becomes 178.0 +/- 4.3 GeV/c^2."
The new value of the top quark mass shifts the best estimate of the
Higgs mass from 96 to 117 GeV/c^2, and the upper bound on the Higgs mass
at the 95 percent confidence level rises from 219 to 251 GeV/c^2.
The impact of the new value of the top mass goes beyond the Higgs boson,
said DZero co-spokesperson Gerald C. Blazey, a physicist from Northern
Illinois University.
"Various supersymmetric theories of particle physics make predictions
for the Higgs mass," Blazey said. "The improved knowledge of the Higgs
mass will help further refine these theories."
Particle theorists predict a new class of heavier, "supersymmetric"
partners for all of the known matter particles of the Standard Model,
the theory of the fundamental particles and forces of nature. Searching
for evidence of supersymmetry is among the key objectives for the CDF
and DZero experiments during Run II at Fermilab's Tevatron.
Fermilab Director Michael Witherell noted that DZero's result does not
end the story of precision measurements of the top quark mass.
"The two collider detectors, CDF and DZero, are recording large amounts
of data in Run II," Witherell said. "The CDF collaboration has recently
reported preliminary new measurements of the top mass based on Run II
data. The precision of the world average will improve further when their
results are final. Over the next few years, both experiments will make
increasingly precise measurements of the top quark mass."
Fermilab is a national laboratory funded by the Office of Science of the
U.S. Department of Energy, operated by Universities Research
Association, Inc. For a list of DZero member institutions, please go to
www-d0.fnal.gov/collaboration/.
###
Date Issued:
June 8th, 2004
Source:
Fermi National Accelerator Laboratory
Content:
Press Release
Contact:
Office of communication
Katie Yurkewicz
+ 1 630 840 3351
+ 1 630 840 8780 (fax)
fermilab@fnal.gov
CDF precision measurement of W-boson mass suggests a lighter Higgs particle
7 January 2007
Fermi National Accelerator Laboratory
Media Contact:
Kurt Riesselmann, Fermilab, kurtr@fnal.gov, +1 630-840-3351
Photos and graphics can be found at:
http://www.fnal.gov/pub/presspass/images/LighterHiggs-images.html
BATAVIA, Illinois - Scientists of the CDF collaboration at the Department of Energy's Fermi National Accelerator Laboratory announced today (January 8, 2007) the world’s most precise measurement by a single experiment of the mass of the W boson, the carrier of the weak nuclear force and a key parameter of the Standard Model of particles and forces. The new W-mass value leads to an estimate for the mass of the yet-undiscovered Higgs boson that is lighter than previously predicted, in principle making observation of this elusive particle more likely by experiments at the Tevatron particle collider at Fermilab.
Scientists working at the Collider Detector at Fermilab measured the mass of the W boson to be 80,413 +/- 48 MeV/c^2, determining the particle’s mass with a precision of 0.06 percent. Calculations based on the Standard Model intricately link the masses of the W boson and the top quark, a particle discovered at Fermilab in 1995, to the mass of the Higgs boson. By measuring the W-boson and top-quark masses with ever greater precision, physicists can restrict the allowable mass range of the Higgs boson, the missing keystone of the Standard Model.
“This new precision determination of the W boson mass by CDF is one of the most challenging and most important measurements from the Tevatron,” said Associate Director for High Energy Physics at DOE’s Office of Science Dr. Robin Staffin. “Together, the W-boson and top-quark masses allow us to triangulate the location of the elusive Higgs boson.”
The CDF result is now the most precise single measurement to date of the W boson mass. Combining the CDF result with other measurements worldwide leads to an average value of the W-boson mass of 80,398 +/- 25 MeV/c^2.
Prior to the announcement of the CDF result, ALEPH, an experiment at CERN, the European Center for Nuclear Research, held the record for the most precise W mass measurement. ALEPH and its three sister experiments at CERN, which operated until 2001, made significant contributions to the measurement of the W’s mass. The experiments relied on electron-positron collisions produced by the LEP collider at CERN. In contrast, CDF experimenters are analyzing proton-antiproton collisions produced by Fermilab’s Tevatron, the world’s most powerful particle collider.
“Compared to the electron-positron collisions at LEP, the proton-antiproton collisions at the Tevatron result in a ‘dirty’ environment experimentally,” said Jacobo Konigsberg, University of Florida physicist and CDF cospokesperson. “Every collision produces hundreds of particles along with the W boson that need to be properly accounted for. That’s why our analysis is so challenging.”
Now, having gained a much better understanding of their detector and the processes it records, CDF scientists are optimistic that they can further improve the precision of their W-mass result by a factor of two in the next couple of years.
“You have to sweat every detail of the analysis,” said Fermilab physicist and cospokesperson Robert Roser. “Our scientists cannot take anything for granted in an environment in which composite particles such as protons and antiprotons collide. We need to understand the many different subatomic processes and take into account the capabilities of our detector for identifying the various particles.”
In a talk at Fermilab on Friday, January 5, Ashutosh Kotwal, CDF collaborator and Professor of Physics at Duke University, presented the W-mass result to the scientific community. The result will be submitted in a paper to Physical Review Letters.
This W mass measurement is yet another major result of Tevatron Run II announced by scientists in the last year, indicating the progress that experimenters have made with both the CDF and the DZero experiments at Fermilab. As the two collaborations continue to take data, collaborators press the search for the Higgs boson as well as for signs of dark matter particles and extra dimensions.
"The CDF and DZero experiments have much more data to analyze, and they are observing more and more collisions at a faster and faster rate,” said Fermilab Director Pier Oddone. “Our experimenters are now in a position to look for some of the rarest and most amazing phenomena that theorists have predicted, as well as to find the completely unexpected. This is a very exciting time."
Notes for editors:
Fermilab is a Department of Energy Office of Science national laboratory operated under contract by the Fermi Research Alliance, LLC.
CDF is an international experiment of 700 physicists from 61 institutions and 13 countries. It is supported by the U.S. Department of Energy, the U.S. National Science Foundation and a number of international funding agencies (the full list can be found at http://www-cdf.fnal.gov/collaboration/Funding_Agencies.html). In 1995, the CDF and DZero experiments discovered the top quark, the final and most massive quark in the Standard Model.
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InterAction Collaboration media contacts:
• Fermilab, Illinois, USA: Kurt Riesselmann, +1 630-840-3351, kurtr@fnal.gov
• INFN, Italy: + 39 06 6868162, + 39 06 6868162 (fax), comunicazione@presid.infn.it
• High Energy Accelerator Research Organization (KEK), Japan: Youhei Morita,
+ 81 029 8796047, + 81 029 8796049 (fax), youhei.morita@kek.jp
• IN2P3-CNRS, France: Alain de Bellefon, + 33 01 44 96 47 51, bellefon@in2p3.fr
• Joint Institute for Nuclear Research, Dubna, Russia: Boris Starchenko, + 7 096 221 6 38 24,
irinak@jinr.ru
• Particle Physics and Astronomy Research Council (PPARC), United Kingdom: Peter Barratt,
+ 44 (0) 1793 442025, + 44 (0) 787 602 899 (mobile), peter.barratt@pparc.ac.uk
• Lawrence Berkeley National Laboratory, California, USA: Ron Kolb, + 1 510 486 7586,
rrkolb@lbl.gov
• CERN, Switzerland: James Gillies, + 41 22 7674101, James.Gillies@cern.ch
Institutions participating in the CDF experiment at Fermilab:
1. Academia Sinica, Taipei, Taiwan
2. Argonne National Laboratory, Argonne, Illinois
3. Institut de Fisica d'Altes Energies (IFAE-Barcelona), Spain
4. Baylor University, Waco, Texas
5. Brandeis University, Waltham, Massachusetts
6. University of California at Davis, Davis, CA
7. University of California at Los Angeles, Los Angeles, CA
8. University of California at San Diego, San Diego, CA
9. University of California at Santa Barbara, Santa Barbara, CA
10. Instituto de Fisica de Cantabria, CSIC-University of Cantabria, 39005 Santander, Spain
11. Carnegie Mellon University, Pittsburgh, PA
12. University of Chicago, Chicago, Illinois
13. Joint Institute for Nuclear Research, Dubna, Russia
14. Duke University, Durham, North Carolina
15. Fermi National Accelerator Laboratory (FNAL), Batavia, Illinois
16. University of Florida, Gainesville, Florida
17. University of Geneva, Switzerland
18. Glasgow University, United Kingdom
19. Harvard University, Cambridge, Massachusetts
20. University of Helsinki, Finland
21. University of Illinois, Urbana, Illinois
22. INFN, University of Bologna, Italy
23. INFN, Laboratori Nazionali di Frascati, Italy
24. INFN Sezione di Padova, Universita di Padova, Italy
25. INFN, University and Scuola Normale Superiore of Pisa, Italy
26. INFN, University di Roma I, Italy
27. INFN, Trieste, Italy, and Universita di Udine, Italy
28. IPP, Institute of Particle Physics, McGill University, Montréal, Canada
29. University of Toronto, Canada
30. ITEP, Institute for Theoretical and Experimental Physics, Moscow, Russia
31. The Johns Hopkins University, Baltimore, Maryland
32. Universitaet Karlsruhe, Germany
33. National Laboratory for High Energy Physics (KEK), Tsukuba, Japan
34. The Center for High Energy Physics (CHEP) Kyungpook National University, Seoul National
University, and SungKyunKwan University, Korea
35. Lawrence Berkeley National Laboratory (LBNL) Berkeley, California
36. University of Liverpool, United Kingdom
37. University College London, United Kingdom
38. CIEMAT, Madrid, Spain
39. Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts
40. Michigan State University, East Lansing, Michigan
41. University of Michigan, Ann Arbor, Michigan
42. University of New Mexico, Albuquerque, New Mexico
43. Northwestern University, Evanston, Illinois
44. The Ohio State University, Columbus, Ohio
45. Osaka City University, Japan
46. Okayama University, Japan
47. University of Oxford, United Kingdom
48. LPNHE and CNRS-IN2P3 - Paris, France
49. University of Pennsylvania, Philadelphia, Pennsylvania
50. University of Pittsburgh, Pittsburgh, Pennsylvania
51. Purdue University, West Lafayette, Indiana
52. University of Rochester, Rochester, New York
53. Rockefeller University, New York, New York
54. Rutgers University, Piscataway, New Jersey
55. Texas A&M University, College Station, Texas
56. Tufts University, Medford, Massachusetts
57. University of Tsukuba, Tsukuba, Japan
58. Waseda University Tokyo, Japan
59. Wayne State University, Detroit, Michigan
60. University of Wisconsin, Madison, Wisconsin
61. Yale University, New Haven, Connecticut
Date Issued:
January 7th, 2007
Source:
Fermi National Accelerator Laboratory
Content:
Press Release
Contact:
Office of communication
Katie Yurkewicz
+ 1 630 840 3351
+ 1 630 840 8780 (fax)
fermilab@fnal.gov
Higgs search update - Media invitation
5 December 2011
European Organization for Nuclear Research
Update on the search for the Higgs boson by the ATLAS and CMS experiments at CERN
Geneva, 6 December 2011. A seminar will be held at CERN on 13 December at which the ATLAS and CMS experiments will present the status of their searches for the Standard Model Higgs boson. These results will be based on the analysis of considerably more data than those presented at the summer conferences, sufficient to make significant progress in the search for the Higgs boson, but not enough to make any conclusive statement on the existence or non-existence of the Higgs.
The seminar begins at 14:00 CET. The auditorium in which the seminar will be held is reserved for CERN personnel and researchers from the laboratory’s user community, but a video stream will be relayed to another auditorium in which scientists will be on hand to answer questions.
At 16:30 CET CERN management and representatives of the two experiments will be available to take questions from the media. Journalists wishing to attend should register with the CERN Press Office. Both the seminar and the following Q&A will be webcast. Journalists following the webcast may submit questions through Twitter using the hashtag #Higgsupdate.
For accreditation with the Press Office please fill in the form at https://indico.cern.ch/conferenceDisplay.py?confId=150980, where updated information will be available.
Best regards,
CERN press office
+41 22 767 34 32/21 41
Press.Office@cern.ch
Date Issued:
December 5th, 2011
Source:
European Organization for Nuclear Research
Content:
Media Invitation
Contact:
Press Office
James Gillies
James.gillies@cern.ch
+ 41 22 76 74101
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