when texas a&m university physicist david toback was elected eight years ago as co-spokesperson and overall physics coordinator for the cdf collaboration at the us department of energys fermi national accelerator laboratory (fermilab) he had one primary goal: to help the groups 400-person active author list publish the collaborations important legacy papers and final results the cover of the current issue of science features a symbolic illustration of the w boson weighing down on the standard model of particle physics the mass of the w boson a mediator of the weak nuclear force is tightly constrained by the theory a new very-high-precision measurement of the w boson mass is in significant tension with the standard model expectation and suggests that improvements to calculations or extensions to the standard model might be needed (credit: carlo cadenas / science) although the collider detector at fermilab experiment representing 54 institutions across 23 countries stopped collecting new data three years before toback assumed his leadership role on june 1 2014 he says its impact lives on in its analysis none bigger than that which graces the cover of the current issue of science announcing the most precise measurement to date of the mass of the w boson one of natures force-carrying particles responsible for the nuclear processes that make the sun shine and particles decay using high-energy particle collisions produced by the tevatron collider at fermilab the cdf collaboration collected huge amounts of data containing w bosons from 1985 to 2011 following 10 years of careful analysis and scrutiny of that data cdf-affiliated scientists led by duke universitys ashutosh v kotwal and the university of oxfords chris hays have now determined the particles mass with a precision of 001% twice as precise as the previous best measurement the achievement corresponds to measuring the weight of an 800-pound gorilla to within 15 ounces the new precision measurement allows scientists to test the standard model of particle physics the theoretical framework that describes nature at its most fundamental level the result: the new mass value shows significant tension with the value scientists expect to obtain using experimental and theoretical inputs in the context of the standard model the standard model is one of the crowning achievements in human history toback said it predicted the existence of the w and z bosons as well as the higgs boson all of which have been discovered but it goes way beyond that in that it makes remarkably precise predictions for what the mass of the w boson should be however weve always known the standard model isnt complete it doesnt explain gravity or dark matter something has to be missing therefore weve been searching for ‘cracks in the standard model for decades to provide a clue to point the way this measurement which represents more than a decade of concerted effort may be one of the most highly scrutinized in cdf history dr david toback toback a high-energy physics expert and veteran researcher in several related international collaborations has been a faculty member in the texas a&m department of physics and astronomy since 2000 where he is the thaman professor for undergraduate teaching excellence and a member of the george p and cynthia woods mitchell institute for fundamental physics and astronomy he began working with the collider detector at fermilab collaboration in 1991 as a graduate student at the university of chicago and has served as co-convener of cdfs top + beyond the standard model group while also guiding the supersymmetry group in 2015 he was elected as a fellow of the american physical society on the basis of his cdf experiment leadership and pioneering work on related searches for new particles toback describes the cdf collaborations latest result is an important contribution to testing the accuracy of the standard model which may need to be improved or extended in the event the measurement is confirmed its now up to the theoretical physics community and other experiments to follow up on this and shed light on this mystery he added if the difference between the experimental and expected value is due to some kind of new particle or subatomic interaction which is one of the possibilities theres a good chance its something that could be discovered in future experiments the collider detector at fermilab recorded high-energy particle collisions produced by the tevatron collider from 1985 to 2011 about 400 scientists at 54 institutions across 23 countries are still analyzing the wealth of data collected by the experiment (credit: fermilab) fermilabs tevatron and cerns large hadron collider (lhc) are the past and current record holders respectively for the most powerful particle colliders on earth after 26 years of colliding particles the tevatron shut down on september 29 2011 with the completion of the lhc however because it observed collisions between protons and antiprotons via its two detectors the three-story 6 000-ton cdf along with its companion dzero physicists widely agree the tevatron produced groundbreaking fundamental results few more intriguing than this one deviations from the standard model are extremely rare said grigory v rogachev professor and head of texas a&m physics and astronomy there may be just a single credible one for instance a magnetic moment of a muon but even that is highly suspect due to difficulties in theoretical analysis it appears that deviation of w boson mass from the standard model prediction may become a central piece in particle physics for years to come this is certainly a very challenging and rewarding measurement added bhaskar dutta texas a&m theoretical physicist and managing director of the mitchell institute it opens up the floor for many new ideas toback is quick to point out that texas a&ms history with the cdf experiment is far more extensive than his involvement given that it was co-founded in 1980 in part by texas a&m physicists peter mcintyre and robert webb texas a&m has had a continuous presence in the collaboration since its inception including four additional physicists toback ricardo eusebi teruki kamon and alexei safonov who either were students or postdoctoral researchers within it and are now among its principal investigators kamon produced the collaborations fourth phd thesis followed by toback (159th 1997) safonov (242nd 2001) and eusebi (345th 2005) all four played lead roles in tevatron run ii with toback leading the team that built the timing system for the cdf electromagnetic calorimeter beyond faculty contributions toback notes that dozens of texas a&m students have earned phds based on cdf-related work while many more have achieved masters degrees and/or did honors undergraduate thesis-related work with cdf in addition many within this collective cdf-inspired whole have gone on to faculty positions including at texas a&m and other prestigious research universities worldwide cdf collaboration 2011 (credit: fermilab) the collaborations prior crowning achievements include discovery of the top quark in 1995 insights into the production rate of charm quarks in 2017 and detection of the first substantive evidence of the higgs boson prior to the large hadron colliders 2012 full discovery that collectively resulted in peter higgs and francois englerts subsequent 2013 nobel prize in physics for theoretically predicting the elusive particles existence 50 years ago in addition to cdf toback serves as a co-principal investigator for the international super cryogenic dark matter search (supercdms) experiment and works in the areas of neutrino physics (dune r&d) quantum computing and big computing his past work includes the dzero experiment at fermilab and the cms experiment at the lhc cdf is in the business of reporting the facts as we know them toback said we take that role very seriously we take this small but clear difference from the standard model very seriously it might just might be the clue we need to crack open the case this has been an exciting adventure an honor and a privilege of the highest degree i am grateful to the texas a&m department of physics and astronomy the mitchell institute and my cdf community colleagues for the continued opportunity to serve the cdf collaboration see todays complete announcement from fermilab to learn more about cdf visit https://cdffnalgov for more information on tobacks broader research visit http://tobackgroupphysicstamuedu/ # # # # # # # # # # about research at texas a&m university: as one of the worlds leading research institutions texas a&m is at the forefront in making significant contributions to scholarship and discovery including in science and technology research conducted at texas a&m generated annual expenditures of more than $113 billion in fiscal year 2020 and ranked 14th in the national science foundations higher education research and development survey texas a&ms research creates new knowledge that provides basic fundamental and applied contributions resulting in many cases in economic benefits to the state nation and world to learn more visit research@texas a&m -atm- contact: shana k hutchins (979) 862-1237 or shutchins@sciencetamuedu or david toback (979) 845-7717 or toback@tamuedu the post cdf collaboration at fermilab achieves most precise measurement of w boson mass appeared first on texas a&m college of science share: