Professor Iain Bertram

Professor of Particle Physics

Research Interests

Two of the major questions facing fundamental physics are:What are the fundamental constituents of the universe and how do they interact? and How did the Universe begin, and how does it evolve?

Currently our best description of the theory of fundamental interactions of particles, the standard model of particle physics (SM), does not describe the Universe we live in. The SM cannot explain the observed matter-antimatter asymmetry of the Universe. This is before we consider the problem the 95% of the Universe that is made up of "dark" matter and energy of which the SM has nothing to say.

I am currently working on the ATLAS experiment based at the Large Hadron Collider (LHC) in Geneva. I searching for phenomena that cannot be explained by the standard model of particle physics. The LHC is running at a centre-of-mass energy of 13 TeV, the highest energy particle collisions ever produced on earth. I am investigating the creation of high energy jets of particles in these proton-proton collisions. In most proton proton collisions two jets of particles are produced. By measuring the energy of each of the jets, physicists can calculate their mass (using Einstein’s E = mc2), this is called the dijet mass. The phenomena I will be searching for include excited quarks, quantum black holes and additional bosons that appear as a peak in the mass spectrum or as a deviation from the predictions of the standard model. The latest results (from an analysis of data collected in 2015 ti 2016) has been published in Physical review D where we probe masses of the order of 5 TeV. Unfortunatley we have not found anything new yet.

I am also working on the confirmation of the X(5568) particle observed by the the DØ experiment using semileptonic decays of the Bs0 meson. The X(5568) is an exiotc particle candidate that is composed of two quarks and two anti-quarks, an up quark, a strange anti-quark, a bottom quark and an anti-down quark (normal matter is made up of baryons with three quarks or mesons made of a quark and an anti-quark). This result will be submitted to Physucal Review D by the end of the year.

My previous research interests are in the experimental investigation of the matter anti-matter asymmetry. On the DØ experiment I carry out research on the decays of particles containing bottom (b)-quarks and charm (c)-quarks. I hope that this research will provide some answers to why the Universe is made of matter.

Specifically over the past five years I have been searching for differences between the behaviour of particles and anti-particles (CP violation) that contain bottom (or b) quarks. The most important of these results is the investigation of the decays of electrically neutral B mesons (particles made up of a quark and an anti-quark, one of them a b-quark) to a muon and other particles: Bs0 → DsμX and Bd0 → D(∗)μX. These processes are especially sensitive to the difference between matter and antimatter. In the process of completing this work I developed new methods to determine the backgrounds to these measurements and methods used to measure the differences between matter and anti-matter improving the statistical sensitivity of the data thereby increasing the value of the data recorded by the experiment. At the time of their publication both of these results were the most precise tests of their kind in the world.

I have made several “standard candle” measurements of CP violation in the decay processes B± → J/ψK±, B± → μ±D0, Ds± → φπ± and D± → Kπ±π±.

I have also used the measurement of Bs0 → DsμX decays to see if the fabric of space has a preferred direction (known as CPT violation or Lorentz violation).

Unfortunately I have not found any new sources of CP-violation that would be able to explain the matter domination of the Universe. I am continuing the search in the decay of mesons containing charm quarks.

Selected Publications Show all 470 publications

Measurement of the forward-backward asymmetry in the production of B± mesons in pp¯ collisions at s√=1.96  TeV
D0 Collaboration 4/02/2015 In: Physical Review Letters. 114, 5, 8 p.
Journal article

Measurement of the direct CP-violating parameter A_CP in the decay D+ -> K- pi+ pi+
D0 Collaboration 11/12/2014 In: Physical Review D. 90, 11, 8 p.
Journal article

Measurement of the Direct CP-violating Charge Asymmetry in D±s→ϕπ± Decays
D0 Collaboration 21/03/2014 In: Physical Review Letters. 112, 8 p.
Journal article

Study of CP-violating charge asymmetries of single muons and like-sign dimuons in pp̅ collisions
D0 Collaboration 14/01/2014 In: Physical Review D. 89, 1, 31 p.
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An improved measurement of direct CP violation parameters in B^+- -> J/psi K^+- and B^+- -> J/psi pi^+- decays
Collaboration, D., Bertram, I., Borissov, G., Ross, A., Williams, M., Ratoff, P., Fox, H., Lamont, I., Beattie, M. 12/06/2013 In: Physical Review Letters. 110, 24, 7 p.
Journal article

Measurement of the semileptonic charge asymmetry using Bs^0 -> D_s mu X decays
Bertram, I., Borissov, G., Williams, M., Fox, H., Ross, A., Ratoff, P., D0 Collaboration, T. 3/01/2013 In: Physical Review Letters. 110, 1, 7 p.
Journal article

Measurement of the semileptonic charge asymmetry in B0 meson mixing with the D0 detector
Collaboration, D., Bertram, I., Borissov, G., Ross, A., Williams, M., Fox, H., Ratoff, P., Price, D. 26/10/2012 In: Physical Review D. 86, 7, 20 p.
Journal article

Measurement of neutrino oscillation parameters from muon neutrino disappearance with an off-axis beam
T2K Collaboration 19/11/2013 In: Physical Review Letters. 111, 21, 7 p.
Journal article

Higgs Boson Studies at the Tevatron
Collaboration, C., Bertram, I., Borissov, G., Fox, H., Ratoff, P., D0 Collaboration, T. 17/09/2013 In: Physical Review D. 88, 5, 27 p.
Journal article

The electromagnetic calorimeter for the T2K near detector ND280
Kormos, L., Bertram, I., Ratoff, P., Bentham, S., Grant, N., Reeves, M., Finch, A., Davies, G., O'Keeffe, H., Hatzikoutelis, A., Maryon, T., Mercer, I., Reeves, M. 17/10/2013 In: Journal of Instrumentation. 8, 10, 42 p.
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Combined search for the Higgs boson with the D0 experiment
Collaboration, D., Bertram, I., Borissov, G., Fox, H., Ratoff, P. 17/09/2013 In: Physical Review D. 88, 5, 17 p.
Journal article

Search for Neutral Higgs Bosons in Events with Multiple Bottom Quarks at the Tevatron
Collaboration, C., Collaboration, D., [No Value], T., Bertram, I., Borissov, G., Fox, H., Ross, A., Williams, M., Ratoff, P. 6/11/2012 In: Physical Review D. 86, 9, 11 p.
Journal article

Measurement of the W Boson Mass with the D0 Detector
Collaboration, D., Bertram, I., Borissov, G., Fox, H., Ross, A., Williams, M., Ratoff, P. 12/04/2012 In: Physical Review Letters. 108, 15, 8 p.
Journal article

Study of direct CP violation in $B^{\pm} \to J/ψK^{\pm}(π^{\pm})$ decays
Collaboration, D., Abazov, V., Bertram, I., Williams, M., Borissov, G., Ratoff, P., Fox, H. 22/02/2008 In: Physical Review Letters. 100, 21, 7 p.
Journal article

Observation and properties of the orbitally excited B_{s2}* Meson
Collaboration, D., Abazov et al, V., Bertram, I., Borissov, G., Fox, H., Love, P., Rakitin, A., Ratoff, P., Sopczak, A., Williams, M. 28/02/2008 In: Physical Review Letters. 100, 8, 7 p.
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Study of the Decay B D D
Collaboration, D., Abazov, V., Bertram, I., Borissov, G., Fox, H., Love, P., Ratoff, P., Sopczak, A., Walder, J. 12/12/2007 In: Physical Review Letters. 99, 24, p. 241801. 7 p.
Journal article

High-pT jets in p¯p collisions at s=630 and 1800 GeV
Abbott, B., Abdesselam, A., Abolins, M., Abramov, V., Acharya, B., Adams, D., Adams, M., Alves, G., Amos, N., Anderson, E., Astur, R., Baarmand, M., Babintsev, V., Babukhadia, L., Bacon, T., Baden, A., Baldin, B., Balm, P., Banerjee, S., Barberis, E., Baringer, P., Bartlett, J., Bassler, U., Bauer, D., Bean, A., Begel, M., Belyaev, A., Beri, S., Bernardi, G., Bertram, I., Besson, A., Beuselinck, R., Bezzubov, V., Bhat, P., Bhatnagar, V., Bhattacharjee, M., Blazey, G., Blessing, S., Boehnlein, A., Bojko, N., Borcherding, F., Brandt, A., Breedon, R., Briskin, G., Brock, R., Brooijmans, G., Bross, A., Buchholz, D., Buehler, M., Buescher, V., Burtovoi, V., Butler, J., Canelli, F., Carvalho, W., Casey, D., Casilum, Z., Castilla-valdez, H., Chakraborty, D., Chan, K., Chekulaev, S., Cho, D., Choi, S., Chopra, S., Christenson, J., Chung, M., Claes, D., Clark, A., Cochran, J., Coney, L., Connolly, B., Cooper, W., Coppage, D., Cummings, M., Cutts, D., Davis, G., Davis, K., De, K., Del Signore, K 11/07/2001 In: Physical Review D. 64, 3
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