graphical representation of quarks
In a recent #CMSPaper, my colleagues (including people in my team at DESY) looked if quarks are really elementary particles, using techniques grounded on the history of quantum physics. CERN has a nice news item about this result: home.cern/news/news/ph...
We approve this message. 🤟
Helmholtz matter in metal font
The start of this week I am not at CERN for CMS week (sorry CMS friends) but instead involved with the preparation of the funding review of the 700-ish million euro MATTER program of the Helmholtz Alliance
And yes we rock 🤘 🎸
data agrees (mostly) at low di-Higgs candidate mass. There is a non-significant excess above 2.5 Tev
Are there heavy undiscovered particles that decay to two Higgs bosons? This #CMSPaper describes the world most sensitive analysis, but we didn't discover any new particles in that signature. We only used data collected up to 2018 though... so more to come! arxiv.org/abs/2601.20011
Want to know more about what particle physics is like, told by others other than only me? Our group's Instagram account gives a voice to a very wide group of scientists
For example, is there is anything inside quarks? Andreas made this nice post about that result
kinematic distribution of W boson pairs from photon fusion
In super rare cases, the collisions in the large hadron collider are not between protons or ions, but between photons! (because protons&ions sometimes create photons) This #CMSPaper #discovers for the first time that W bosons (2 of them) are created in such photon-fusion collisions buff.ly/ej68FJd
Beautiful upsilon peaks. As said, the only difference is how the b-quarks are configured inside the particle
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
Different places in CMS where the fourth gen lepton could show up in the muon system
Is there a fourth lepton and we just didn't see it because of the very tight online selection that detectors like CMS typically apply? This #CMSPaper uses the 'no cuts' scouting data to search for such leptons, assuming they behave a bit like a tau lepton, but heavier! arxiv.org/abs/2601.20063
invariant mass distribution. Is ther ea peak there? Maybe, but it is definitely not significant!
Are there undiscovered particles that decay to a Higgs boson and a photon? Or a Z boson and a photon? (at high momentum it's difficult to see the difference between a Higgs boson and a Z boson) This #CMSPaper looks for a very massive resonance from such a particle. arxiv.org/abs/2511.14583
took the German or Autistic diagnostic and I'm apparently just German. Personally I think I’m more Dutch, but there are many similarities. Kant would approve. And I definitely approve of Kant.
The CMS pixel detector and its support structure show up beautifully when studying the backgrounds for this paper
Are there undiscovered particles being produced at the LHC that we just missed? This #CMSPaper looks for such long-lived particles. Understanding the detector is very important there as known particles can make that signature when they traverse the material of our detector arxiv.org/abs/2511.08212
scan of the unmeasurable parts of the total mass present in LHC events (no sign of something extra, within 20-ish percent or even less accurate)
Are there #Darkmatter particles produced together with #Higgsbosons? This #CMSPaper looks for that signature in the LHC data collected in 2017 and 2018. It is a #NullResult arxiv.org/abs/2601.11330
measuring missing energy relies on precisely measuring every particle in the collision, and here you see how well the ML does
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
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
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
Is er werkelijk geen echt nieuws?
heldelberg physics graduate days logo
Coming week, I am lecturing particle physics at the Heidelberg University doctoral school. I will discuss questions for particle physics right now. We have a spin-zero particle we don't really understand (the HIggs boson) and to understand it we need more tech. I look forward to the lectures!
non-significant Higgs peak (orange is the prediction, the data could agree with anything)
This #CMSPaper measures the Higgs boson when it has high momentum. This is important to test the standard model because deviations are more likely to show up there. But we don't really see the Higgs boson there yet. This result will help when combined with other results tho! arxiv.org/abs/2601.05362
spin behaviour of top quarks (versus the mass of the production system) in data (points) and different standard model calculations (red and blue lines)
This #CMSPaper measures the spin behaviour of top quark pairs. As that also can be calculated accurately in the standard model, it is important information to check precision measurements (and has links to things like quantum entanglement of top quarks) arxiv.org/abs/2512.17557
Even with four years of data, diboson resonances below ~ 1.5 TeV cannot be easily excluded for some models like the one in this plot.
Are there new heavy particles that decay to the Higgs, W or Z bosons we know from the standard model? This #CMSPaper compares and combines the very diverse techniques used on the data collected during 2015-2018, and gives a final say on what we can (and cannot) exclude arxiv.org/abs/2601.12583
scanning the four-lepton invariant mass spectrum, no bumps visible
The Higgs boson can decay to many different particles from the standard model. But... is the Higgs boson also decaying to undiscovered particles? This #CMSPaper looks for extra (light) bosons that would create the Higgs boson to four electron signature arxiv.org/abs/2511.19563
Btw this paper has very important contributions from our group at DESY and includes work from doctoral students I supervised 👩🏫 🎓️
graphic showing how a long-lived particle can make an electron that seems to be appearing out of nowhere in the detector
Non-standard signatures like long-lived particles can be very difficult to spot. And as the LHC throws away over 99% of it's background data, it is super important to be sure we keep those long-lived particles, and this #CMSPaper summarises all we do to make that happen arxiv.org/abs/2601.17544
Comparison of the photons to the standard model, in the Zeppenfeld variable
This #CMSPaper looks for production of photons in these boson collisions, meaning the LHC is a W boson collider, which is the first time this has ever been seen! It measures properties of the photons produced and compares them to the standard model predictions arxiv.org/abs/2512.00502
distribution of Z bosons and photons.
This #CMSPaper measures the simultaneous production of Z bosons and photons. That way their interactions can be measured and can be compared to predictions by the standard model arxiv.org/abs/2512.08582
dimuon invariant mass distribution. No significant bumps to be seen.
Are there extra Z-boson like undiscovered particles made at higher mass? Or did we miss them because they can only see them when they're made together with quarks? This #CMSPaper scans the dimuon spectrum - it is a #nullresult (no extra Z' bosons spotted!) arxiv.org/abs/2511.11853
It is a result from our group at DESY by the way :)
machine learning is used to find these displaced taus, by rejecting all other tau-like things coming from the standard model. This plot shows what score between 0 and 1 the machine learning gives a displaced tau candidate.
If there are supersymmetry versions of tau leptons (creatively called stau/scalar-tau), they could create signatures where normal taus appear in the middle of the CMS detector. This #CMSPaper looks for displaced taus, and describes the #machinelearning needed to spot them arxiv.org/abs/2601.17576
there are some excesses in this analysis by the way, but nothing too exciting yet. Stay tuned, we have a lot more data in hand!
Are there undiscovered charged heavy Higgs bosons? If they are heavier than the top quark, they would decay into a top quark + b quark signature. This #CMSPaper looks for these, and also compares them in dedicated theory frameworks that include neutral heavy Higgs bosons arxiv.org/abs/2512.24471
Comparison of different (supervised) machine learning searches
One of the classical ways to look for undiscovered particles at the LHC is to look for unexpected resonances in the jets coming from quarks and gluons. This #CMSPaper compares the cutting edge of #machinelearnining #ai methods to see how well they do for top quark resonances arxiv.org/abs/2512.20395
yep I have another reason to dance :) thanks!