The search for signatures of supersymmetric models remains one of the main item on the BSM search program at the LHC, with EW SUSY partners still allowed with masses as low as a few hundred GeV. Over the last years, searches for the “golden channel”, $$pp \rightarrow \tilde{\chi }_{2}^0 \tilde{\chi }_{1}^\pm \rightarrow \tilde{\chi }_{1}^0 Z^{(*)} \, \tilde{\chi }_{1}^0 W^{\pm (*)}$$ show consistent excesses between ATLAS and CMS in the 2 soft-lepton and 3 soft-lepton plus $$E_T\hspace{-4.5mm}/$$ searches, assuming and $$\Delta m_{21}{:=} m_{\tilde{\chi }_{2}^0} - m_{\tilde{\chi }_{1}^0} \approx 20 \,\, \textrm{GeV}$$ . We interpret these excesses in the framework of the Next-to-Minimal Supersymmetric Standard Model (NMSSM). We assume a singlino dominated lightest neutralino, $$\tilde{\chi }_{1}^0$$ , as a Dark Matter (DM) candidate. The second and third lightest neutralinos, $$\tilde{\chi }_{2,3}^0$$ are higgsino like, with the higgsino mixing parameter $$\mu $$ being smaller than the soft SUSY-breaking bino and wino masses, $$M_1$$ and $$M_2$$ . We furthermore assume the approximate GUT relations $$M_1 \sim M_2/2 \sim M_3/6$$ , with the implication for our scenario of a gluino mass . Scalar fermion masses are assumed to be heavy and do not play a role in our analysis. We find that this scenario is in agreement with all relevant experimental constraints, comprising the LHC searches for SUSY particles and additional Higgs bosons, the LHC Higgs-boson rate measurements, the DM direct detection limits and the upper limit on the DM relic density. We demonstrate that this scenario gives an excellent description of the observed excesses in the search for 2 and 3 soft-leptons plus $$E_T\hspace{-4.5mm}/$$ , with $$m_{\tilde{\chi }_{2}^0} \sim m_{\tilde{\chi }_{3}^0} \sim m_{\tilde{\chi }_{1}^\pm }$$ and $$\Delta m_{21} \sim 20 \,\, \textrm{GeV}$$ . This constitutes the first explanation of the soft-lepton excesses in a model with GUT relations among the soft SUSY-breaking parameters.

Italy

Emanuele Bagnaschi

United Kingdom

Manimala Chakraborti

Spain

Sven Heinemeyer

India

Ipsita Saha

Consistent excesses in the LHC electroweak SUSY searches: GUT-based Singlino/Higgsino interpretation in the NMSSM

Belgium

Chiara Arina

France

Benjamin Fuks

Luca Panizzi

United States

Michael Baker

South Africa

Alan Cornell

Germany

Jan Heisig

Benedikt Maier

Portugal

Rute Pedro

Dominique Trischuk

Diyar Agin

Alexandre Arbey

Giorgio Arcadi

Kehang Bai

Brazil

Disha Bhatia

Mathias Becker

Alexander Belyaev

Ferdinand Benoit

Monika Blanke

Canada

Jackson Burzynski

Jonathan Butterworth

Antimo Cagnotta

China

Lorenzo Calibbi

Linda Carpenter

Xabier Cid Vidal

Emanuele Copello

Louie Corpe

Francesco D’Eramo

Aldo Deandrea

Australia

Aman Desai

Caterina Doglioni

South Korea

Sunil Dogra

Mathias Garny

Mark Goodsell

Norway

Sohaib Hassan

Philip Harris

Julia Harz

Alejandro Ibarra

Alberto Iorio

Felix Kahlhoefer

Deepak Kar

Egypt

Shaaban Khalil

Valery Khoze

Pyungwon Ko

Sabine Kraml

Greg Landsberg

Andre Lessa

Laura Lopez-Honorez

Alberto Mariotti

Vasiliki Mitsou

Kirtimaan Mohan

Chang-Seong Moon

Colombia

Alexander Moreno Briceno

Maria Moreno Llacer

Leandre Munoz-Aillaud

Taylor Murphy

Anele Ncube

Wandile Nzuza

Clarisse Prat

Lena Rathmann

Thobani Sangweni

Dipan Sengupta

William Shepherd

Sukanya Sinha

Tim Tait

Andrea Thamm

Michel Tytgat

Zirui Wang

David Yu

Shin-Shan Yu

Publisher Erratum: $\textit{t}$-channel dark matter models – a whitepaper

This report, summarising work achieved in the context of the LHC Dark Matter Working Group, investigates the phenomenology of $\textit{t}$-channel dark matter models, spanning minimal setups with a single dark matter candidate and mediator to more complex constructions closer to UV-complete models. For each considered class of models, we examine collider, cosmological and astrophysical implications. In addition, we explore scenarios with either promptly decaying or long-lived particles, as well as featuring diverse dark matter production mechanisms in the early universe. By providing a unified analysis framework, numerical tools and guidelines, this work aims to support future experimental and theoretical efforts in exploring $\textit{t}$-channel dark matter models at colliders and in cosmology.

$\textit{t}$-channel dark matter models – a whitepaper

We discuss the possibility that light new physics in the top-quark sample at the LHC can be found by investigating with greater care well-known kinematic distributions, such as the invariant mass <math><msub><mi>m</mi><mrow><mi>b</mi><mo>ℓ</mo></mrow></msub></math> of the <math><mi>b</mi></math>-jet and the charged lepton in fully leptonic <math><mi>t</mi><mover><mi>t</mi><mo>¯</mo></mover></math> events. We demonstrate that new physics can be probed in the rising part of the already measured <math><msub><mi>m</mi><mrow><mi>b</mi><mo>ℓ</mo></mrow></msub></math> distribution. To this end, we analyze a concrete supersymmetric scenario with a light right-handed top-squark, chargino and neutralino. The corresponding spectra are characterized by small mass differences, which make them not yet excluded by current LHC searches and give rise to a specific end point in the shape of the <math><msub><mi>m</mi><mrow><mi>b</mi><mo>ℓ</mo></mrow></msub></math> distribution. We argue that this sharp feature is general for models of light new physics that have so far escaped the LHC searches and can offer a precious handle for the implementation of robust searches that exploit, rather than suffer from, soft bottom quarks and leptons. Recasting public data on searches for new physics, we identify candidate models that are not yet excluded. For these models, we study the <math><msub><mi>m</mi><mrow><mi>b</mi><mo>ℓ</mo></mrow></msub></math> distribution and derive the expected signal yields, finding that there is untapped potential for discovery of new physics using the <math><msub><mi>m</mi><mrow><mi>b</mi><mo>ℓ</mo></mrow></msub></math> distribution.

CERN

Gennaro Corcella

Roberto Franceschini

Dibyashree Sengupta

Rise and Fall of Light Top Squarks in the LHC Top-Quark Sample

We present a new Monte Carlo code for Higgs boson pair production at next-to-leading order in the Powheg-Box Monte Carlo framework. The code is based on analytic results for the two loop virtual corrections which include the full top quark mass dependence. This feature allows to freely assign the value of all input parameters, including the trilinear Higgs boson self coupling, as well as to vary the renormalization scheme employed for the top quark mass. We study the uncertainties due to the top-mass renormalization scheme allowing the trilinear Higgs boson self coupling to vary around its Standard Model value including parton shower effects. Results are presented for both inclusive and differential observables.

Giuseppe Degrassi

Ramona Gröber

Higgs boson pair production at NLO in the Powheg approach and the top quark mass uncertainties

One of the most important mechanisms at the Large Hadron Collider (LHC) for the production of the pseudoscalar Higgs boson of the Minimal Supersymmetric Standard Model (MSSM) is the loop-induced gluon fusion process gg → A. The higher-order QCD corrections have been obtained a long time ago and turned out to be large. However, the genuine supersymmetric (SUSY–)QCD corrections have been obtained only in the limit of large SUSY particle masses so far. We describe our calculation of the next-to-leading-order (NLO) SUSY-QCD results with full mass dependence and present numerical results for a few representative benchmark points. We also address the treatment of the effective top and bottom Yukawa couplings, in the case of heavy SUSY particles, in terms of effective low-energy theories where the heavy degrees of freedom have been decoupled. Furthermore, we include a discussion of the relation between the SUSY-QCD corrections that we have computed and the Adler-Bardeen theorem for the axial anomaly. In addition, we apply our results to the gluonic and photonic pseudoscalar Higgs decays A → gg, γγ at NLO.

Switzerland

Lukas Fritz

Stefan Liebler

Margarete Mühlleitner

Thanh Nguyen

Michael Spira

Pseudoscalar MSSM Higgs Production at NLO SUSY-QCD

We address the prediction for the mass of the SM-like Higgs boson in NMSSM scenarios where all BSM particles, including the singlets, have masses at the TeV scale. We provide a full one-loop computation of the matching condition for the quartic Higgs coupling in the NMSSM, supplemented with the two-loop contributions that involve the strong gauge coupling. We discuss the impact of the one- and two-loop corrections that are specific to the NMSSM on the prediction for the Higgs mass, and propose a method to estimate of the uncertainty associated with the uncomputed higher-order terms. Finally, we illustrate how the measured value of the Higgs mass can be used to constrain some yet-unmeasured parameters of the NMSSM.

Pietro Slavich

Higgs-mass prediction in the NMSSM with heavy BSM particles

We use the Fitmaker tool to incorporate the recent CDF measurement of m  W  in a global fit to electroweak, Higgs, and diboson data in the Standard Model Effective Field Theory (SMEFT) including dimension-6 operators at linear order. We find that including any one of the SMEFT operators   <math> <mi>O</mi> </math>  $$ \mathcal{O} $$   HWB ,   <math> <mi>O</mi> </math>  $$ \mathcal{O} $$   HD ,   <math> <mi>O</mi> </math>  $$ \mathcal{O} $$  ℓℓ or   <math> <msubsup> <mi>O</mi> <mrow> <mi>H</mi> <mi>ℓ</mi> </mrow> <mfenced> <mn>3</mn> </mfenced> </msubsup> </math>  $$ {\mathcal{O}}_{H\ell}^{(3)} $$  with a non-zero coefficient could provide a better fit than the Standard Model, with the strongest pull for   <math> <mi>O</mi> </math>  $$ \mathcal{O} $$   HD  and no tension with other electroweak precision data. We then analyse which tree-level single-field extensions of the Standard Model could generate such operator coefficients with the appropriate sign, and discuss the masses and couplings of these fields that best fit the CDF measurement and other data. In particular, the global fit favours either a singlet Z′ vector boson, a scalar electroweak triplet with zero hypercharge, or a vector electroweak triplet with unit hypercharge, followed by a singlet heavy neutral lepton, all with masses in the multi-TeV range for unit coupling.

Estonia

John Ellis

Maeve Madigan

Ken Mimasu

Veronica Sanz

Tevong You

SMEFT analysis of m  W

The field of particle physics is at the crossroads. The discovery of a Higgs-like boson completed the Standard Model (SM), but the lacking observation of convincing resonances Beyond the SM (BSM) offers no guidance for the future of particle physics. On the other hand, the motivation for New Physics has not diminished and is, in fact, reinforced by several striking anomalous results in many experiments. Here we summarise the status of the most significant anomalies, including the most recent results for the flavour anomalies, the multi-lepton anomalies at the LHC, the Higgs-like excess at around 96 GeV, and anomalies in neutrino physics, astrophysics, cosmology, and cosmic rays. While the LHC promises up to 4  $$\hbox {ab}^{-1}$$  <math> <msup> <mtext>ab</mtext> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> </math>   of integrated luminosity and far-reaching physics programmes to unveil BSM physics, we consider the possibility that the latter could be tested with present data, but that systemic shortcomings of the experiments and their search strategies may preclude their discovery for several reasons, including: final states consisting in soft particles only, associated production processes, QCD-like final states, close-by SM resonances, and SUSY scenarios where no missing energy is produced. New search strategies could help to unveil the hidden BSM signatures, devised by making use of the CERN open data as a new testing ground. We discuss the CERN open data with its policies, challenges, and potential usefulness for the community. We showcase the example of the CMS collaboration, which is the only collaboration regularly releasing some of its data. We find it important to stress that individuals using public data for their own research does not imply competition with experimental efforts, but rather provides unique opportunities to give guidance for further BSM searches by the collaborations. Wide access to open data is paramount to fully exploit the LHCs potential.

Oliver Fischer

Bruce Mellado

Stefan Antusch

Shankha Banerjee

Geoff Beck

Benedetta Belfatto

Matthew Bellis

Zurab Berezhiani

Bernat Capdevila

Taiwan

Kingman Cheung

Andreas Crivellin

Nishita Desai

Bhupal Dev

Rohini Godbole

Tao Han

Martin Hoferichter

Matthew Kirk

Austria

Suchita Kulkarni

Clemens Lange

Finland

Kati Lassila-Perini

Zhen Liu

Farvah Mahmoudi

Claudio Manzari

David Marzocca

Biswarup Mukhopadhyaya

Antonio Pich

Xifeng Ruan

Luc Schnell

Jesse Thaler

Susanne Westhoff

Unveiling hidden physics at the LHC

The electroweak (EW) sector of the Minimal Supersymmetric extension of the Standard Model (MSSM), assuming the lightest neutralino as Dark Matter (DM) candidate, can account for a variety of experimental results. This includes the DM direct detection limits, the searches for EW superpartners at the LHC, and in particular the discrepancy between the experimental result for the anomalous magnetic moment of the muon,  $$(g-2)_\mu $$  <math> <msub> <mrow> <mo>(</mo> <mi>g</mi> <mo>-</mo> <mn>2</mn> <mo>)</mo> </mrow> <mi>μ</mi> </msub> </math>  , and its Standard Model (SM) prediction. The new “MUON G-2” result, combined with the older BNL result on  $$(g-2)_\mu $$  <math> <msub> <mrow> <mo>(</mo> <mi>g</mi> <mo>-</mo> <mn>2</mn> <mo>)</mo> </mrow> <mi>μ</mi> </msub> </math>  , yields a deviation from the SM prediction of  $$\Delta a_\mu = ({25.1}\pm {5.9}) \times 10^{-10}$$  <math> <mrow> <mi>Δ</mi> <msub> <mi>a</mi> <mi>μ</mi> </msub> <mo>=</mo> <mrow> <mo>(</mo> <mrow> <mn>25.1</mn> </mrow> <mo>±</mo> <mrow> <mn>5.9</mn> </mrow> <mo>)</mo> </mrow> <mo>×</mo> <msup> <mn>10</mn> <mrow> <mo>-</mo> <mn>10</mn> </mrow> </msup> </mrow> </math>  , corresponding to  $${4.2}\,\sigma $$  <math> <mrow> <mrow> <mn>4.2</mn> </mrow> <mspace width="0.166667em"></mspace> <mi>σ</mi> </mrow> </math>  . Using this updated bound, together with the other constraints, we calculate the MSSM prediction for the mass of the W boson,  $$M_W$$  <math> <msub> <mi>M</mi> <mi>W</mi> </msub> </math>  . We assume contributions only from the EW sector, i.e. the colored sector of the MSSM, in agreement with the search limits, is taken to be heavy. We investigate five scenarios, distinguished by the mechanisms which yield a relic DM density in agreement with the latest Planck bounds. We find that with the new  $$(g-2)_\mu $$  <math> <msub> <mrow> <mo>(</mo> <mi>g</mi> <mo>-</mo> <mn>2</mn> <mo>)</mo> </mrow> <mi>μ</mi> </msub> </math>   result taken into account and depending on the scenario, values up to      are reached. The largest values are obtained for wino DM and in the case of slepton co-annihilation, where points well within the  $$1\,\sigma $$  <math> <mrow> <mn>1</mn> <mspace width="0.166667em"></mspace> <mi>σ</mi> </mrow> </math>   range of the experimental world average of  $$M_W^{\mathrm {exp}}= 80.379 \pm 0.012 \,\, \mathrm {GeV}$$  <math> <mrow> <msubsup> <mi>M</mi> <mi>W</mi> <mi>exp</mi> </msubsup> <mo>=</mo> <mn>80.379</mn> <mo>±</mo> <mn>0.012</mn> <mspace width="0.166667em"></mspace> <mspace width="0.166667em"></mspace> <mi>GeV</mi> </mrow> </math>   are reached, whereas the SM predicts a too small value of  $$M_W^{\mathrm {SM}}= 80.353 \,\, \mathrm {GeV}$$  <math> <mrow> <msubsup> <mi>M</mi> <mi>W</mi> <mi>SM</mi> </msubsup> <mo>=</mo> <mn>80.353</mn> <mspace width="0.166667em"></mspace> <mspace width="0.166667em"></mspace> <mi>GeV</mi> </mrow> </math>  . We analyze the dependence of  $$M_W^{\mathrm {MSSM}}$$  <math> <msubsup> <mi>M</mi> <mi>W</mi> <mi>MSSM</mi> </msubsup> </math>   on the relevant masses of the EW superpartners and demonstrate that future  $$M_W$$  <math> <msub> <mi>M</mi> <mi>W</mi> </msub> </math>   measurements, e.g. at the ILC, could distinguish between various MSSM realizations. Sizable contributions to  $$M_W^{\mathrm {MSSM}}$$  <math> <msubsup> <mi>M</mi> <mi>W</mi> <mi>MSSM</mi> </msubsup> </math>   are associated with a relatively light  $$\tilde{\chi }_{1}^0$$  <math> <msubsup> <mover> <mi>χ</mi> <mo>~</mo> </mover> <mrow> <mn>1</mn> </mrow> <mn>0</mn> </msubsup> </math>  , accompanied by either a light chargino or a light smuon, setting interesting targets for future collider searches.

Poland

Japan

Georg Weiglein

Interdependence of the new “MUON G-2” result and the W-boson mass