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Freya BlekmanOne of the problems with the standard model is that we use different mathematics for low-energy than for high-energy strong force calculations. The transition region is not so easy. <a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1392 measures the transition region for the first time in LHC heavy ion collisions <a href="https://arxiv.org/abs/2503.19993" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.19993</a>

Freya Blekman<a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1398 does a meta-analysis of CMS results with Higgs bosons, Z and W bosons, and top quarks. It is interpreted in the Standard Model Effective Theory, looking for subtle changes with respect to the predictions of the standard model that are seen over more than one signature. The plot shows that the predictions agree within 1.7% with the standard model as a whole <a href="https://arxiv.org/abs/2504.02958" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2504.02958</a>

Freya BlekmanWhat and how precisely will the LHCb, Belle2, ATLAS and CMS experiments be able to measure 15 years from now? This is an important factor in deciding if and what kind of collider to build in the future, as an expensive collider should obviously measure something new. This <a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1397 gives those projections for some benchmark important physics results (mainly with a focus on b quark precision measurements, things like that) <a href="https://indico.cern.ch/event/1439855/contributions/6461613/attachments/3045991/5381958/ESPPU_Joint_Flavour_Physics_Experiment-final.pdf" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://indico.cern.ch/event/1439855/contributions/6461613/attachments/3045991/5381958/ESPPU_Joint_Flavour_Physics_Experiment-final.pdf</a> (no @arxiv <a href="https://sciencemastodon.com/tags/openscience" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#openscience</a> fail)

Freya BlekmanpreciselyWhat and how precise will the ATLAS and CMS experiments be able to measure 15 years from now? This is an important factor in deciding if and what kind of collider to build in the future, as an expensive collider should obviously measure something new. This <a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1396 gives those projections for some benchmark important physics results (mainly with a focus on Higgs bosons) <a href="https://arxiv.org/abs/2504.00672" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2504.00672</a>

Freya Blekman<a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1395 observes a totally unexpected extra behaviour of <a href="https://sciencemastodon.com/tags/topquark" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#topquark</a> pair production; we see significantly more top quarks than we expect, and they kind of behave like they come from something particle-like. We are reluctant to just call it topponium, but definitely stay tuned to see if ATLAS also confirms and sees this! <a href="https://arxiv.org/abs/2503.22382" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.22382</a>

Freya BlekmanCollisions where three different force carriers interact are uncommon in the standard model, so also at the LHC. This <a href="https://sciencemastodon.com/tags/CMSpaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSpaper</a> 1394 confirms the observation of a Z, W boson and a photon together, previously seen by ATLAS. These super-rare collisions would be much more common if there were other particles that could make that signature (like Axion-like particles) so we can set limits on those as well with this discovery paper <a href="https://arxiv.org/abs/2503.21977" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.21977</a>

Freya BlekmanThere are many clear signs of <a href="https://sciencemastodon.com/tags/darkmatter" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#darkmatter</a> from cosmology and astrophysics. This <a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1393 looks at whether we can make dark matter in LHC collisions, in collisions where one top quark is made potentially with dark matter. We did not see any signs of that in that signature <a href="https://arxiv.org/abs/2503.20033" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.20033</a>

Freya Blekman<a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1391 is a <a href="https://sciencemastodon.com/tags/nullresult" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#nullresult</a> that looks for undiscovered particles that travel halfway through the CMS detector before they decay to standard model particles. As these particles normally don't make it to the muon system, we look for photons in the muon system <a href="https://arxiv.org/abs/2503.16699" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.16699</a>

Freya BlekmanThe W and Z boson, the "photons of the weak force" still carry important and previously unknown information, particularly on how quarks and gluons in protons behave (and stick together) at the high energies of the LHC. This <a href="https://sciencemastodon.com/tags/CMSpaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSpaper</a> 1390 measures W and Z boson production <a href="https://arxiv.org/abs/2503.09742" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.09742</a>

Freya Blekman<a href="https://sciencemastodon.com/tags/CMSpaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSpaper</a> 1388 measures J/Psi particles in LHC collisions where lead ions just fly past each other instead of hard collide. The fact that new particles are still made, is a really good way to measure the properties of gluons in big atomic nucleus systems like lead <a href="https://arxiv.org/abs/2503.08903" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.08903</a>

Freya BlekmanUnderstanding the Higgs boson's interaction with lighter particles is vital for confirming its role with respect to mass. The production of Higgs bosons together with charm quarks is a very good way to measure this. <a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1387 shows we are not close to seeing that (yet!) <a href="https://arxiv.org/abs/2503.08797" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.08797</a>

Freya Blekman<a href="https://sciencemastodon.com/tags/CMSpaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSpaper</a> 1386 examines deviations in extra quark/gluon jet production in lepton-rich collisions, expected to follow a power law decline. The study focuses on Z+W boson signatures plus up to 5+ extra jets. We use this <a href="https://sciencemastodon.com/tags/nullresult" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#nullresult</a> to constrain supersymmetry predictions arxiv.org/abs/2503.06726

Freya BlekmanAt the LHC, we spend a lot of time throwing away uninteresting collisions. So it's crucial to know how many collisions happened (= "integrated luminosity", how bright our collider was). <a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1385 describes how we measure the total number of proton-lead collisions arxiv.org/abs/2503.03946

Freya BlekmanStudying particles in busy vs not-so-busy events is key to understanding composite particles, and normally we compare particles with different quarks. <a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1384 innovatively compares particles with same quarks, showing unexpected differences depending on travel distance arxiv.org/abs/2503.02139

Freya Blekman<a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1392 looks for signatures of heavy undiscovered particles (leptoquarks in this case) in the kinematic behaviour of events with two leptons (electrons or muons). It did not see anything inconsistent with the standard model but did use <a href="https://sciencemastodon.com/tags/machinelearning" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#machinelearning</a> to be extra sensitive. So REALLY did not see any deviations (actually, an undershoot even) <a href="https://arxiv.org/abs/2503.20023" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.20023</a>

Freya BlekmanOne of the problems with the standard model is that we use different mathematics for low-energy strong force calculations than for high-energy strong force calculations. The transition region is not so easy to pinpoint. In a new <a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1392, we have measured this transition (with a method that relies on comparing the correlations between low and high energy particles inside sprays of particles). This is the first time this is observed in heavy ion collisions at the LHC <a href="https://arxiv.org/abs/2503.19993" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.19993</a>

Freya Blekman<a href="https://sciencemastodon.com/tags/CMSPaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSPaper</a> 1391 is a <a href="https://sciencemastodon.com/tags/nullresult" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#nullresult</a> that looks for undiscovered particles that travel halfway through the CMS detector before they decay to standard model particles. As these particles normally don't make it to the muon system, we look for photons in the muon system. This is an important new result, as not seeing anything provides limits to Grand Unification Theories, some String theory predictions, and models that rely on extra dimensions existing <a href="https://arxiv.org/abs/2503.16699" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.16699</a>

Freya BlekmanThe W and Z boson, the "photons of the weak force" are produced often at the LHC. But they still carry important and previously unknown information, particularly on how the quarks and gluons in protons behave (and stick together) at the high energies of the LHC. This <a href="https://sciencemastodon.com/tags/CMSpaper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CMSpaper</a> 1390 measures and compares W and Z boson production to the cutting edge of theory calculations <a href="https://arxiv.org/abs/2503.09742" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.09742</a>

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