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Freya Blekman

@freyablekman.bsky.social
3.6K followers 639 following 2.2K posts

Particle physicist at @CMSExperiment at @CERN - Lead Scientist DESY & Professor of Physics University of Hamburg - World citizen ➡🇳🇱🇺🇸 🇬🇧🇨🇭🇧🇪🇩🇪 Posts: #physics #SciComm + academia/tech stuff + my opinions + summaries of #CMSpapers

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Freya Blekman @freyablekman.bsky.social · 16h
Another successful PhD combining ambitious machine learning and particle physics! Congratulations to Shahzad Sanjrani, who defended his PhD on “Performance of an attention-based neural network on the search for top-Philip resonances in the all-hadronic four-top final state at CMS”.
Shahzad and his PhD advisors after the defense
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Freya Blekman @freyablekman.bsky.social · 10/10/2026
ATLAS !
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Freya Blekman @freyablekman.bsky.social · 10/10/2026
ATLAS!
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Freya Blekman @freyablekman.bsky.social · 10/10/2026
Visiting ATLAS @atlasexperiment.bsky.social today (thank you ATLAS outreach team and Connie Potter for your help booking the tour)
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Freya Blekman @freyablekman.bsky.social · 24/09/2026
Fresh off the press: next year there will be another CERN open day: 24, 25 and 26 September 2027 ! (pic: a group I took to visit the CMS detector at one of the collision points of the large hadron collider. For CMS visits, guides have a white helmet, visitors in orange, or sometimes blue)
people in front of the CMS experiment
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Freya Blekman @freyablekman.bsky.social · 21/09/2026
This week I'm in sunny Graz in Austria, speaking about Higgs bosons and why we need a future collider to measure them properly, presenting a so-called mini-colloquium . It's at the 75th Annual Meeting of the Austrian Physical Society, good times will be had. I've never been to #Graz, any tips?
Logo of the 75th Annual Meeting of the Austrian Physical Society
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Freya Blekman @freyablekman.bsky.social · 14/09/2026
So many historic science objects on our campus in #hamburg This time: a van de Graaff generator! #hamburg #wisskomm #particlephysics #accelerator #science
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Freya Blekman @freyablekman.bsky.social · 09/09/2026
My colleague Anna Benecke is hiring a PhD student in the context starting her DESY group. More details here: inspirehep.net/jobs/3195484
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Freya Blekman @freyablekman.bsky.social · 08/09/2026
If you are in the Hamburg area: My colleagues Christian Schwanenberger and Beate Heinemann are taking part in this interesting #STEAM event: ndkh.de/kirchen/?chu...
poster of Gloria Bruni's opera "Schöpfung Fragmente"Panel discussion titled "Glaube trifft Wissenschaft" with speakers Prof. Dr. Beate Heinemann, Prof. Bazon Brock, and composer Gloria Bruni; Saturday, 12 September at 19:00, Blankeneser Kirche am Markt, shown on a maroon event poster.Panel discussion titled "Glaube trifft Wissenschaft" with speakers Prof. Dr. Beate Heinemann, Prof. Bazon Brock, and composer Gloria Bruni; Saturday, 12 September at 19:00, Blankeneser Kirche am Markt
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Freya Blekman @freyablekman.bsky.social · 02/09/2026
Some exciting #darkmatter #physics news from a mine in South Dakota. But no Nobel prizes any time soon. I explain why in this a bit longer explanation video
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Freya Blekman @freyablekman.bsky.social · 26/08/2026
Every layer of a Dolly Parton outfit had a job: structure, sparkle, warmth, all of it in service of the show. Particle detectors are built the same way, layer after layer, each tuned for a different job, working together to catch what matters. Thank you #DollyParton for the sparkle and the song
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Freya Blekman @freyablekman.bsky.social · 26/08/2026
Every layer of a Dolly Parton outfit had a job: structure, sparkle, warmth, all of it in service of the show. Particle detectors are built the same way, layer after layer, each tuned for a different job, working together to catch what matters. Thank you #DollyParton for the sparkle and the song
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Freya Blekman @freyablekman.bsky.social · 26/08/2026
Every layer of a Dolly Parton outfit had a job: structure, sparkle, warmth, all of it in service of the show. Particle detectors are built the same way, layer after layer, each tuned for a different job, working together to catch what matters. Thank you #DollyParton for the sparkle and the song
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Freya Blekman @freyablekman.bsky.social · 25/08/2026
Every layer of a Dolly Parton outfit had a job: structure, sparkle, warmth, all of it in service of the show. Particle detectors are built the same way, layer after layer, each tuned for a different job, working together to catch what matters. Thank you #DollyParton for the sparkle and the song
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Freya Blekman @freyablekman.bsky.social · 01/08/2026
Ambitious #science and definitely particle physics are almost always a #team effort. This is also true for conferences. Here you see Pedro (Portugal), Azwinndini (South Africa), Kate (UK), Sandra (Brazil), and friends, together we presently are organising a track at the #ichep2026 conference
Selfie with physicists
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Freya Blekman @freyablekman.bsky.social · 31/07/2026
This week I’m at a conference. Physics conferences have of course talks about physics, but about much more! For example this morning, I gave a talk about how we run our group Instagram account (and why we do it that way) #ichep2026 particle physics is #openscience so talk is here: indi.to/vjPHb
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Freya Blekman @freyablekman.bsky.social · 15/07/2026
This time in random gear I found on campus: the monochromator You’ve probably seen a prism split light into a rainbow. X-rays can be split the same way with a crystal monochromator instead of glass. The antique monochromator in this video is a real piece of that history.
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Freya Blekman @freyablekman.bsky.social · 08/07/2026
There are 2 postdoctoral positions opening in the CMS group at DESY, more details here: lnkd.in/evBjrzkt (yes they are in my group) Please don't hesitate to forward this job announcement to suitable candidates.
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Freya Blekman @freyablekman.bsky.social · 15/06/2026
We are celebrating the renewal of our #hamburg #clusterofexcellence #quantumuniverse. With science. And art! And singing physicists !
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Freya Blekman @freyablekman.bsky.social · 12/06/2026
I love speaking at festivals! Today at Kimiko festival in Aachen. First time the CERN festival programme touches down in Germany 🇩🇪
Freya next to a neon sign that reads: science is magic that works
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Freya Blekman @freyablekman.bsky.social · 12/06/2026
Ready for some mud and physics at the @kimikofestival as part of the #bigbangcollective. I’m wearing a particularly obscure festival t-shirt. Because I can 👌
Selfie. In a raincoat so you can’t see the obscure festival t shirt. It’s from ATP, for those in the know
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Freya Blekman @freyablekman.bsky.social · 11/06/2026
How quarks cluster together into hadrons is only partially understood. With heavy quarks it is easier to calculate and measuring bound bottom quark-antiquark pairs is therefor super important to understand this aspect of the strong force. This #CMSPaper measures the Upsilon particles buff.ly/p5QZ00p
Beautiful upsilon peaks. As said, the only difference is how the b-quarks are configured inside the particle
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Freya Blekman @freyablekman.bsky.social · 11/06/2026
Top quarks are usually produced in quark-antiquark pairs, but through the weak interaction, it is possible to create single top quarks too. This #CMSPaper measures one of the single top quark production modes, and provides important input to measure and understand quantum fluctuations inside protons
probability (we call that cross section) of the production of single top quark in the t-channel, as a function of collision energy
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Freya Blekman @freyablekman.bsky.social · 10/06/2026
There are many predictions for undiscovered particles that are similar to the Higgs particle. This #CMSPaper looks for the double whammy: two different undiscovered Higgs-like particles! It is the first time this was done. We didn't see anything but also used limited data arxiv.org/abs/2602.00273
checking for a peak. No significant peaks here.
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Freya Blekman @freyablekman.bsky.social · 10/06/2026
The LHC colllides protons, and protons contain quarks (and gluons). Almost all collisions involve only one quark (or gluon) from each proton, but the super-rare collisions where two particles in the one proton collide simultaneously with two particles in another proton arxiv.org/abs/2602.02770
Y meson and Z boson peaks involved in the selection of these collisions
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Freya Blekman @freyablekman.bsky.social · 10/06/2026
A DESY scientist walks into a music festival.. not a joke! On Friday, 12 June, I'll be at the CERN Science Hub at @kimikofestival! . Kein Vorwissen nötig. Nur Neugier. / No prior knowledge needed. Just curiosity. kimiko-festival.de/science-tech/
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Freya Blekman @freyablekman.bsky.social · 09/06/2026
This is a big one: the #CMSPaper summarising all precise Higgs boson measurements on data collected in 2016, 2017 and 2018. We agree with the standard model prediction for the total number of Higgs bosons, within 5-6% those are still big uncertainties for particle physics) arxiv.org/abs/2602.18611
Higgs-y summary plot. It compares whether the Higgs particle indeed interacts more strongly with particles depending on the particle mass. If the dat is on the red diagonal line, it agrees with the standard model prediction
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Freya Blekman @freyablekman.bsky.social · 09/06/2026
A DESY scientist walks into a music festival.. not a joke! On Friday, 12 June, I'll be at the CERN Science Hub at @kimikofestival talking Am Freitag, 12. Juni bin ich im CERN Science Hub beim @kimikofestival und spreche über die kleinsten Bausteine und die großen Fragen, die sie aufwerfen.
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Freya Blekman @freyablekman.bsky.social · 07/06/2026
Guess what… today I’m on a train again, from Hamburg to Geneva as next week is CMS collaboration week. (More about that next week). But noteworthy of my 11 hour trans-European train trip today is that DEUTSCHE BAHN IS RUNNING AHEAD OF SCHEDULE. 10 min even. yes very exciting. Hence the all caps.
Train sign. The train is 10 minutes early.
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Freya Blekman @freyablekman.bsky.social · 04/06/2026
Tonight (well hopefully soon) I am taking the sleeper train from Stockholm to Hamburg. It is not starting well. We are already delayed even before departing. Something about one of the cars not completely working #trains
Selfie of Freya and the train. The train is very much standing still
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Freya Blekman @freyablekman.bsky.social · 03/06/2026
You have another chance to see the (may I say: excellent!) science-related short films on the walls of the Science City Hamburg Bahrenfeld campus (aka DESY/UHH campus) on 5 June. #AWallIsAScreen after all awallisascreen.com And yes, there will also be science! On walls :)
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Freya Blekman @freyablekman.bsky.social · 03/06/2026
Imposter syndrome doesn’t mean you don’t belong. It often means the opposite, that you care deeply about what you do. I asked my colleagues to join me, because many of the most accomplished, world-leading scientists have felt like “frauds” at times. #academia #impostersyndrome #physics
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Freya Blekman @freyablekman.bsky.social · 02/06/2026
To accurately reconstruct all particles in LHC collision, CMS uses a technique called "Particle Flow". This #CMSPaper shows how the newest, #machinelearning based particle flow algorithm performs in recent data and how well it does at rejecting extra uninteresting collisions arxiv.org/abs/2601.17554
measuring missing energy relies on precisely measuring every particle in the collision, and here you see how well the ML does
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Freya Blekman @freyablekman.bsky.social · 02/06/2026
This #CMSPaper measures interactions between photons and Z bosons (quantum particles of electromagnetism and weak force). And measures if there are effects that explain why our universe contains more matter than antimatter. It's the most sensitive result for that signature arxiv.org/abs/2601.14102
the standard model cannot explain why there is more matter than antimatter. And this result agrees with the standard model, which is why the little cross is inside the big yellow ellipse
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Freya Blekman @freyablekman.bsky.social · 02/06/2026
This week I am in #stockholm at the #cometa @multibosons European research network. Yesterday I gave a talk for the general public about the large hadron collider, particle physics and the Nobel prize (and I gave a talk for scientists today).
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Freya Blekman @freyablekman.bsky.social · 01/06/2026
Experiments like CMS need algorithms called a trigger to decide which of the ~ 1 in 1000 events they want to keep (the other 999 are thrown away). This #CMSPaper describes the #machinelearning that is needed to do that for tau leptons arxiv.org/abs/2602.11359
performance of the tau trigger, and comparison between data and simulation
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Freya Blekman @freyablekman.bsky.social · 01/06/2026
This is a big one: the #CMSPaper summarising all precise Higgs boson measurements on data collected in 2016, 2017 and 2018. We agree with the standard model prediction for the total number of Higgs bosons, within 5-6% those are still big uncertainties for particle physics) arxiv.org/abs/2602.18611
Higgs-y summary plot. It compares whether the Higgs particle indeed interacts more strongly with particles depending on the particle mass. If the dat is on the red diagonal line, it agrees with the standard model prediction
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Freya Blekman @freyablekman.bsky.social · 01/06/2026
The LHC colllides protons, and protons contain quarks (and gluons). Almost all collisions involve only one quark (or gluon) from each proton, but the super-rare collisions where two particles in the one proton collide simultaneously with two particles in another proton arxiv.org/abs/2602.02770
Y meson and Z boson peaks involved in the selection of these collisions
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Freya Blekman @freyablekman.bsky.social · 31/05/2026
There are many predictions for undiscovered particles that are similar to the Higgs particle. This #CMSPaper looks for the double whammy: two different undiscovered Higgs-like particles! It is the first time this was done. We didn't see anything but also used limited data arxiv.org/abs/2602.00273
checking for a peak. No significant peaks here.
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Freya Blekman @freyablekman.bsky.social · 31/05/2026
This paper measures the polarisation of gluons within particle cascades. It turns out that the quantum particle of the strong nuclear force needs to be modelled with polarisation to reproduce the data. This #CMSPaper is important for understanding the strong nuclear force arxiv.org/abs/2603.03689
comparing the models to the data, if there would be no polarisation this plot would be horizontal.
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Freya Blekman @freyablekman.bsky.social · 31/05/2026
The W boson can decay to leptons (which is how the super-precise W boson mass measurements are done), but most W bosons decay into quarks. Because we know the mass super accurately, this #CMSPaper uses the known W mass to better understand the way quarks from W bosons decay arxiv.org/abs/2603.19963
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Freya Blekman @freyablekman.bsky.social · 30/05/2026
Top quarks are usually produced in quark-antiquark pairs, but through the weak interaction, it is possible to create single top quarks too. This #CMSPaper measures one of the single top quark production modes, and provides important input to measure and understand quantum fluctuations inside protons
probability (we call that cross section) of the production of single top quark in the t-channel, as a function of collision energy
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Freya Blekman @freyablekman.bsky.social · 30/05/2026
You may wonder what happens next: CERN has until 2028 to develop a financially feasible funding plan, after which the Council, which is essentially all the science ministries of CERN countries, will make a final go/no-go decision on the FCC-ee project. 5/6
Picture that Freya took during FCC week.
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Freya Blekman @freyablekman.bsky.social · 30/05/2026
I have a personal connection to this milestone. About 8 years ago I was a convener on the FCC-ee physics studies, back when this was still very much a long-term dream. Being so close to this process from just a crazy idea to a CERN Council decision is very exciting 4/6
Freya talking about FCC in Vienna on their famous ferris wheel
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Freya Blekman @freyablekman.bsky.social · 30/05/2026
FCC-ee would be an electron-positron “Higgs factory that would produce millions of Higgs bosons in clean collisions, letting us measure it with a precision the LHC simply can't match. We’re talking about probing whether the Higgs is exactly what the Standard Model predicts 3/6
artist impression of a collision in an FCC detector
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Freya Blekman @freyablekman.bsky.social · 30/05/2026
For those who follow my CMS paper summaries: the LHC (and its High-Luminosity upgrade) remains the top priority right now, we still have ~15 years of incredible physics ahead of us. But ... what comes AFTER 2041? 2/6
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Freya Blekman @freyablekman.bsky.social · 30/05/2026
🧵 Big news for particle physics this week, and honestly for me personally too. The CERN Council has officially adopted the updated European Strategy for Particle Physics — and the recommendation is clear: FCC-ee is the preferred next flagship collider after the LHC. 1/6
The FCC could become a reality! but for now this is an artists impression of switzerfrance with circles where the FCC COULD be built
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Freya Blekman @freyablekman.bsky.social · 29/05/2026
How quarks cluster together into hadrons is only partially understood. With heavy quarks it is easier to calculate and measuring bound bottom quark-antiquark pairs is therefor super important to understand this aspect of the strong force. This #CMSPaper measures the Upsilon particles buff.ly/p5QZ00p
Beautiful upsilon peaks. As said, the only difference is how the b-quarks are configured inside the particle
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Freya Blekman @freyablekman.bsky.social · 29/05/2026
now even with image :)
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Freya Blekman @freyablekman.bsky.social · 28/05/2026
Are there pairs of undiscovered extra Higgs particles produced? This #CMSPaper looks for those. And doesn't see much, in a very difficult signature where there is not much data yet. But the LHC has only taken 15% of all its data, so more to do! arxiv.org/abs/2602.18223
we use a machine learning called boosted decision trees in this result. Here you see its output
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