Freya Blekman

searchign the e-mu invariant mass for a Z boson peak. No sign.

The LHC produces a large number of Z bosons. So it is worthwhile checking if some of them behave inconsistently with the standard model. This #CMSPaper measured that the chance that Z bosons decay to two different kinds of leptons is smaller than one in 10 million arxiv.org/abs/2508.07512

invariant mass distribution that is nicely falling. The data agrees with the blue prediction (which is the standard model). The scenarios considered would modify these signatures dramatically (other coloured lines)

Are there undiscovered particles (that are very light for LHC standard) produced in Higgs boson decays? This #CMSPaper describes how we look for them, but did not see any arxiv.org/abs/2508.06947

competitive limits on supersymmetric lepton partners (aka sleptons)

If you need a reference model of what an extension of the standard model with many new particles would look like, Supersymmetry is a good benchmark. This #CMSPaper shows a general search in many standard signatures, looking for deviations spread over different signatures arxiv.org/abs/2508.13900

limit plot, measuring that in the most sensitive scenarios that if such an undiscovered particle exists, it shows up in fewer than 1/10000 B mesons

Are there invisible (and long-lived) undiscovered particles produced in the decays of B mesons? Those would be super rare, so we use a huge dataset of B mesons with dedicated data taking techniques. We didn't see any new particles though, this #CMSPaper is a #nullresult arxiv.org/abs/2508.06363

Yes. And now with crispy pistachios

Unpopular opinion: #dubaichocolate is made with low quality chocolate and is horrible.

Open to recommendations without shitty palm fat or sub 50% cocoa chocolate and with sugar levels suitable for adults instead of toddlers

Plot showing how the Deepmet algorithm improves the missing energy reconstruction of the very well-known W boson particle. Compared to the previous best algorithms (it's really very good!)

Missing momentum is effectively the only way that the main detectors at the LHC (like CMS) can measure the indirect signs of neutrinos (or undiscovered particles). This #CMSPaper present how we use #machinelearning to make our missing momentum measurement much, much better: arxiv.org/abs/2509.12012

a cartoon character says " it 's all over people " in front of a house ALT: a cartoon character says " it 's all over people " in front of a house

Earlier this week, Dominic, a postdoc in our team, also had a two hour delay in switzerland (on the Hamburg->Geneva route)

don't worry, I still have plenty of complaints:

- it's raining in Hamburg
- I spilt coffee on myself halfway so had to travel with dirty (but still awesome) deftones t-shirt

do note that there were a lot of children near me on the train and they all behaved. So that's a plus.

Map of Europe with train route from Geneva to Hamburg. It’s far.

Especially for the haters I would like to confirm that my train trip arrived 6 minutes EARLY from CERN, Geneva to DESY, Hamburg (ok to my home in Hamburg), that’s 1250 km, 2 changes.

You may have noticed that I stopped numbering the #CMSPapers I posted about. This is mostly because the numbering is kind of ambiguous. But we have published over 1400 papers (of which 1370+ on LHC data) since 2009 already!

check them all out (searchable) here: cms-results-search.web.cern.ch

beautiful D meson peak!

This #CMSPaper measures D mesons (particles containing charm and other quarks) produced in collisions when the LHC works as a photon-heavy ion collider. These results help as input to nuclear physics in general, and used in predictions in astrophysics, for example arxiv.org/abs/2509.08626

SMEFT limit plot

We have enough Higgs bosons now to measure kinematics and check for additional quarks and gluons formed. These numbers could vary due to slight changes in the standard model from undiscovered particles. This #CMSPaper compares these distributions to the standard model arxiv.org/abs/2509.07958

limit plot.

We don't see the decay of the Higgs boson to charm quarks (yet!), but it is also possible to measure the interaction of the Higgs boson with charm by studying those particles being produced together. This #CMSPaper studies that Higgs+charm signature (we don't see it yet): arxiv.org/abs/2508.14988

This #CMSpaper looks again at a non-significant (but intriguing!) excess in signatures consistent with two unstable, unknown particles from a heavier source. This paper further compares to theory predictions explaining these four-jet events
arxiv.org/abs/2507.17884

three peaks of a B meson plus a photon

This #CMSPaper explores the excitation of three particles with a B quark and other quark, examining how they store extra energy beyond the ground state. It marks the first simultaneous measurement of these particles. This improves knowledge of particles that contain quarks arxiv.org/abs/2508.05820

Invariant mass distribution looking for a Higgs boson (in the diphoton decay)

Are there undiscovered particles that decay to a Higgs boson and something else? This #CMSPaper describes how we scanned the invariant mass spectrum, but did not find any signs (in very very few events, and this should be rare. We will do this again when we have more data) arxiv.org/abs/2508.11494

Yesterday I got to geek out when I visited some of the labs where we are building the new detectors for the LHC upgrade. Can you guess what this little sub-sub-subdetector is for?

Hint: it’s not made of glass but of scintillation crystals…

searchign the e-mu invariant mass for a Z boson peak. No sign.

The LHC produces a large number of Z bosons. So it is worthwhile checking if some of them behave inconsistently with the standard model. This #CMSPaper measured that the chance that Z bosons decay to two different kinds of leptons is smaller than one in 10 million arxiv.org/abs/2508.07512

invariant mass distribution that is nicely falling. The data agrees with the blue prediction (which is the standard model). The scenarios considered would modify these signatures dramatically (other coloured lines)

Are there undiscovered particles (that are very light for LHC standard) produced in Higgs boson decays? This #CMSPaper describes how we look for them, but did not see any arxiv.org/abs/2508.06947

competitive limits on supersymmetric lepton partners (aka sleptons)

If you need a reference model of what an extension of the standard model with many new particles would look like, Supersymmetry is a good benchmark. This #CMSPaper shows a general search in many standard signatures, looking for deviations spread over different signatures arxiv.org/abs/2508.13900

limit plot, measuring that in the most sensitive scenarios that if such an undiscovered particle exists, it shows up in fewer than 1/10000 B mesons

Are there invisible (and long-lived) undiscovered particles produced in the decays of B mesons? Those would be super rare, so we use a huge dataset of B mesons with dedicated data taking techniques. We didn't see any new particles though, this #CMSPaper is a #nullresult arxiv.org/abs/2508.06363

This #CMSpaper looks again at a non-significant (but intriguing!) excess in signatures consistent with two unstable, unknown particles from a heavier source. This paper further compares to theory predictions explaining these four-jet events
arxiv.org/abs/2507.17884

three peaks of a B meson plus a photon

This CMS Paper explores the excitation of three particles with a B quark and other quark, examining how they store extra energy beyond the ground state. It marks the first simultaneous measurement of these particles. This improves knowledge of particles that contain quarks arxiv.org/abs/2508.05820

Invariant mass distribution looking for a Higgs boson (in the diphoton decay)

Are there undiscovered particles that decay to a Higgs boson and something else? This #CMSPaper describes how we scanned the invariant mass spectrum, but did not find any signs (in very very few events, and this should be rare. We will do this again when we have more data) arxiv.org/abs/2508.11494

searchign the e-mu invariant mass for a Z boson peak. No sign.

The LHC produces a large number of Z bosons. So it is worthwhile checking if some of them behave inconsistently with the standard model. This #CMSPaper measured that the chance that Z bosons decay to two different kinds of leptons is smaller than one in 10 million arxiv.org/abs/2508.07512

invariant mass distribution that is nicely falling. The data agrees with the blue prediction (which is the standard model). The scenarios considered would modify these signatures dramatically (other coloured lines)

Are there undiscovered particles (that are very light for LHC standard) produced in Higgs boson decays? This #CMSPaper describes how we look for them, but did not see any arxiv.org/abs/2508.06947

Fokke & Sukke via nrc.nl

I just went for work to Helgoland, where quantum physics was born 100 years ago.

Are you a young researcher as excited about quantum physics as I am? And maybe you want to contribute to the next 100 years of quantum physics? Then check out this workshop: indico.desy.de/event/50023/

competitive limits on supersymmetric lepton partners (aka sleptons)

If you need a reference model of what an extension of the standard model with many new particles would look like, Supersymmetry is a good benchmark. This #CMSPaper shows a general search in many standard signatures, looking for deviations spread over different signatures arxiv.org/abs/2508.13900