A measurement of the angular structure of inclusive jets and those containing a prompt D meson in proton-proton collisions at the LHC at a center-of-mass energy of 5.02 TeV is presented. The data corresponding to an integrated luminosity of 301 pb were collected by the CMS experiment in 2017. Two jet grooming algorithms, late-$\textit{k}$ and soft drop, are used to study the intrajet radiation pattern using iterative Cambridge-Aachen declustering. The splitting-angle distributions of jets with transverse momentum ($\textit{p}$ ) of around 100 GeV, obtained with these two algorithms, show that there is a shift of the distribution for jets containing a prompt D meson with respect to inclusive jets. The suppression of emissions at small angles observed in the late-$\textit{k}$ grooming approach is consistent with the dead-cone effect, whereas the similar suppression for splittings selected with the soft-drop algorithm appears to be induced by gluon splitting to charm quark-antiquark pairs at large angles. The measured distributions are corrected to the particle level and can be used to constrain model predictions for the substructure of high-$\textit{p}$ charm quark jets.

Armenia

V. Chekhovsky

A. Hayrapetyan

V. Makarenko

A. Tumasyan

Austria

W. Adam

J. Andrejkovic

L. Benato

T. Bergauer

K. Damanakis

M. Dragicevic

C. Giordano

P. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

I. Mikulec

J. Schieck

D. Schwarz

R. Schöfbeck

M. Sonawane

W. Waltenberger

C.E. Wulz

Belgium

T. Janssen

H. Kwon

T. Laer

P. Mechelen

J. Bierkens

N. Breugelmans

J. D’Hondt

S. Dansana

A. Moor

M. Delcourt

F. Heyen

Y. Hong

S. Lowette

I. Makarenko

D. Müller

S. Tavernier

M. Tytgat

G. Onsem

S. Putte

D. Vannerom

B. Bilin

B. Clerbaux

A. Das

I. Bruyn

G. Lentdecker

H. Evard

L. Favart

P. Gianneios

A. Khalilzadeh

F. Khan

A. Malara

M. Shahzad

L. Thomas

M. Bemden

C. Vander Velde

P. Vanlaer

F. Zhang

M. Coen

D. Dobur

G. Gokbulut

J. Knolle

L. Lambrecht

D. Marckx

K. Skovpen

N. Bossche

J. Linden

J. Vandenbroeck

L. Wezenbeek

S. Bein

A. Benecke

A. Bethani

G. Bruno

A. Cappati

J. De Favereau De Jeneret

C. Delaere

A. Giammanco

A. Guzel

Sa. Jain

V. Lemaitre

J. Lidrych

P. Mastrapasqua

S. Turkcapar

Brazil

G. Alves

E. Coelho

G. Correia Silva

C. Hensel

T. Menezes De Oliveira

C. Mora Herrera

P. Rebello Teles

M. Soeiro

E. Tonelli Manganote

A. Vilela Pereira

W. Aldá Júnior

M. Barroso Ferreira Filho

H. Brandao Malbouisson

W. Carvalho

J. Chinellato

Exploring small-angle emissions in charm quark jets in proton-proton collisions at $$ \sqrt{s}=5.02 $$ TeV

Differential top quark pair production cross sections are measured in the dilepton final states e e , μ μ , and e μ , as a function of kinematic variables of the two-neutrino system: the transverse momentum $$ {p}_{\textrm{T}}^{\nu \nu} $$ of the dineutrino system, the minimum distance in azimuthal angle between $$ {\overrightarrow{p}}_{\textrm{T}}^{\nu \nu} $$ and leptons, and in two dimensions in bins of both observables. The measurements are performed using CERN LHC proton-proton collisions at $$ \sqrt{s}=13 $$ TeV, recorded by the CMS detector between 2016 and 2018, corresponding to an integrated luminosity of 138 fb . The measured cross sections are unfolded to the particle level using an unregularized least squares method. Results are compared with predictions by the standard model of particle physics, and found to be in agreement with theoretical calculations as well as Monte Carlo simulations.

E. Costa

G. Silveira

Measurement of the dineutrino system kinematic variables in dileptonic top quark pair production in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV

We present a search for the pair production of Higgsinos in final states with large missing transverse momentum and either two reconstructed muons or a reconstructed lepton (muon or electron) and an isolated track. The analyzed data correspond to proton-proton collisions with an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>137</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>, collected by the CMS experiment at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math> in 2016, 2017, and 2018. The signal scenario assumes four nearly mass degenerate Higgsino mass eigenstates: two neutralino states <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mover accent="true"><mrow><mi>χ</mi></mrow><mrow><mo stretchy="false">˜</mo></mrow></mover></mrow><mrow><mn>2</mn></mrow><mrow><mn>0</mn></mrow></msubsup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mover accent="true"><mrow><mi>χ</mi></mrow><mrow><mo stretchy="false">˜</mo></mrow></mover></mrow><mrow><mn>1</mn></mrow><mrow><mn>0</mn></mrow></msubsup></mrow></math> with a small mass difference in the range 1–10 GeV and two chargino states <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mover accent="true"><mrow><mi>χ</mi></mrow><mrow><mo stretchy="false">˜</mo></mrow></mover></mrow><mrow><mn>1</mn></mrow><mrow><mo>±</mo></mrow></msubsup></mrow></math> with an intermediate mass. The analysis focuses on the decay of the heavier neutralino into the lighter one and a virtual <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> boson, which decays into two same-flavor leptons. The leptons have small transverse momentum and/or a small opening angle between the identified muons. An isolated track is used to recover events in which only one of the two leptons is identified. Multivariate discriminants are used to enhance the sensitivity by efficiently rejecting backgrounds from SM processes or misreconstructed tracks and/or leptons. The search explores a unique phase space and probes a previously unexplored region of the signal model parameter space. Mass differences between the two neutralinos are probed down to 1.5 GeV, assuming a Higgsino mass of 100 GeV. The maximum excluded Higgsino mass is 115 GeV.

J.W. Andrejkovic

P.S. Hussain

M. Matthewman

M. Shooshtari

D. Ocampo Henao

T. Van Laer

P. Van Mechelen

A. De Moor

P. Kashko

J. Song

G.P. Van Onsem

S. Van Putte

A.K. Das

I. De Bruyn

G. De Lentdecker

F.A. Khan

M.A. Shahzad

M. Vanden Bemden

M. De Coen

A.M. Tomaru

N. Van Den Bossche

J. van der Linden

A.O. Guzel

P. Malek

G.A. Alves

E.J. Tonelli Manganote

W.L. Aldá Júnior

Search for Higgsinos in final states with low-momentum lepton-track pairs at 13 TeV

A search for pairs of light neutral pseudoscalar bosons (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>A</mi></mrow></math>) resulting from the decay of a Higgs boson is performed. The search is conducted using LHC proton-proton collision data at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mrow><mi>TeV</mi></mrow></mrow></math>, collected with the CMS detector in 2016–2018 and corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>138</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>fb</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math>. The <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>A</mi></mrow></math> boson decays into a highly collimated electron-positron pair. A novel multivariate algorithm using tracks and calorimeter information is developed to identify these distinctive signatures, and events are selected with two such merged electron-positron pairs. No significant excess above the standard model background predictions is observed. Upper limits on the branching fraction for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>H</mi><mo stretchy="false">→</mo><mrow><mi>A</mi><mi>A</mi></mrow><mo stretchy="false">→</mo><mn>4</mn><mi>e</mi></mrow></math> are set at 95% confidence level, for masses between 10 and 100 MeV and proper decay lengths below <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>100</mn><mtext> </mtext><mtext> </mtext><mi mathvariant="normal">μ</mi><mrow><mi mathvariant="normal">m</mi></mrow></mrow></math>, reaching branching fraction sensitivities as low as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup></mrow></math>. This is the first search for Higgs boson decays to four electrons via light pseudoscalars at the LHC. It significantly improves the experimental sensitivity to axionlike particles with masses below 100 MeV .

F. Gameiro Casalinho

Search for Light Pseudoscalar Bosons, Pair-Produced in Higgs Boson Decays in the Four-Electron Final State in Proton-Proton Collisions at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math>

A search for heavy long-lived charged particles at the LHC is presented. Particles traversing the CMS muon detector across several bunch crossings are searched for using a data sample of proton-proton collisions at <math altimg='si15.svg'><mrow><msqrt><mi>s</mi></msqrt><mo linebreak='goodbreak'>=</mo><mn>13.6</mn><mspace width='0.33em' /><mtext>TeV</mtext></mrow></math> collected with the CMS detector in 2024, corresponding to an integrated luminosity of 3.7 fb <math altimg='si16.svg'><msup><mrow /><mrow><mo>&#8722;</mo><mn>1</mn></mrow></msup></math>. This is the first search using the novel level-1 trigger scouting data set collected without any trigger selection, allowing correlations between bunch crossings to be analyzed. The results are interpreted as upper limits on the cross sections of several benchmark processes with pair production of heavy long-lived charged particles. Upper limits on the fiducial cross section of a heavy long-lived charged particle with <math altimg='si11.svg'><mrow><msub><mi>p</mi><mi mathvariant='normal'>T</mi></msub><mo linebreak='goodbreak'>&gt;</mo><mn>500</mn><mspace width='0.16em' /><mtext>GeV</mtext></mrow></math> and | <italic>&#951;</italic>|&#8239;&lt;&#8239;0.83 are also set in different ranges of <math altimg='si17.svg'><mrow><mi>&#946;</mi><mo linebreak='goodbreak'>=</mo><mi>v</mi><mo linebreak='goodbreak'>/</mo><mi>c</mi></mrow></math>. This analysis is a proof of concept for the level-1 trigger data scouting system and complements existing searches for heavy long-lived charged particles by extending the sensitivity to lower <italic>&#946;</italic> values.

A. Sharma

K. Kaspar

D. Kavtaradze

H. Aarup Petersen

D. Matos Figueiredo

Search for heavy long-lived charged particles with level-1 trigger scouting data from proton-proton collisions at <math altimg='si15.svg'><mrow><msqrt><mi>s</mi></msqrt><mo linebreak='goodbreak'>=</mo><mn>13.6</mn><mspace width='0.33em' /><mtext>TeV</mtext></mrow></math>

The first observation of electroweak production of a photon in association with two forward jets in proton-proton collisions is presented. The measurement uses data recorded by the CMS experiment at the LHC during 2016–2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb . The analysis is performed in a region enriched in photon production via vector boson fusion, with a requirement on the transverse momentum of the photon to exceed 200 GeV. The cross section is measured to be $$ {202}_{-32}^{+36} $$ fb, at a significance with respect to the null hypothesis that exceeds five standard deviations. This is in agreement with the standard model prediction of $$ {177}_{-12}^{+13} $$ fb. Differential cross sections are measured as a function of various observables. Limits are set on dimension-6 effective field theory operators that contribute to the WWγ interaction. The observed 95% confidence intervals for the corresponding Warsaw basis Wilson coefficients $\textit{c}$ and $\textit{c}$ are [$\textit{−}$0$\textit{.}$11$\textit{,}$ 0$\textit{.}$16] and [$\textit{−}$1$\textit{.}$6$\textit{,}$ 1$\textit{.}$5], respectively.

Measurements of electroweak production of a photon in association with two jets in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV

A search for new physics in events featuring a single photon and missing transverse momentum is presented, using proton-proton <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math> collision data corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>101</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> collected by the CMS experiment at the CERN LHC between 2017 and 2018. This analysis, combined with a previous study of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>36</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> of 2016 data (totaling <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>137</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>), reveals no significant deviations from standard model expectations. The results are then used to establish 95% confidence level limits on parameters in theoretical models involving dark matter and large extra dimensions. Compared to the 2016-only analysis, this search achieves up to a 14% improvement in exclusion reach for mediator masses in simplified dark matter models, along with 11% and 10% enhancements in the limits on the effective field theory suppression scale and the fundamental Planck scale, respectively. These results are the most stringent constraints on these parameters to date.

Search for new physics in the final state with a single photon and large missing transverse momentum in proton-proton collisions at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>

At hadron colliders, the net transverse momentum of particles that do not interact with the detector (missing transverse momentum, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mover accent="true"><mi>p</mi><mo stretchy="false">→</mo></mover><mi mathvariant="normal">T</mi><mrow><mi>miss</mi></mrow></msubsup></math>) is a crucial observable in many analyses. In the standard model, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mover accent="true"><mi>p</mi><mo stretchy="false">→</mo></mover><mi mathvariant="normal">T</mi><mrow><mi>miss</mi></mrow></msubsup></math> originates from neutrinos. Many beyond-the-standard-model particles, such as dark matter candidates, are also expected to leave the experimental apparatus undetected. This paper presents a novel deep neural network based <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mover accent="true"><mi>p</mi><mo stretchy="false">→</mo></mover><mi mathvariant="normal">T</mi><mrow><mi>miss</mi></mrow></msubsup></math> estimator, deepmet, developed by the CMS Collaboration at the LHC. The deepmet algorithm produces a weight for each reconstructed particle based on its properties. The estimator is based on the negative vector sum of the weighted transverse momenta of all reconstructed particles in an event. Compared with other estimators currently employed by CMS, deepmet improves the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mover accent="true"><mi>p</mi><mo stretchy="false">→</mo></mover><mi mathvariant="normal">T</mi><mrow><mi>miss</mi></mrow></msubsup></math> resolution by 10%–30%, shows improvement for a wide range of final states, is easier to train, and is more resilient against the effects of additional proton-proton interactions accompanying the collision of interest.

Improving missing transverse momentum estimation with a deep neural network

A measurement of the substructure of bottom quark jets (b jets) in proton-proton (pp) collisions is presented. The measurement uses data collected in pp collisions at $$ \sqrt{s}=5.02 $$ TeV, with a low number of simultaneous interactions per bunch crossing, recorded by the CMS experiment in 2017, corresponding to an integrated luminosity of 301 pb . An algorithm to identify and cluster the charged decay daughters of b hadrons is developed for this analysis, which facilitates the exposure of the gluon radiation pattern of b jets using iterative Cambridge-Aachen declustering. The soft-drop-groomed jet radius, $\textit{R}$ , and momentum balance, $\textit{z}$ , of b quark jets are presented. These observables can be used to test perturbative quantum chromodynamics predictions that account for mass effects. Because the b hadron is partially reconstructed from its charged decay daughters, only charged particles are used for the jet substructure studies. In addition, a jet fragmentation function, $\textit{z}$ , is measured, which is defined as the distribution of the ratio of the transverse momentum ($\textit{p}$ ) of the partially reconstructed b hadron with respect to the charged-particle component of the jet $\textit{p}$ . The substructure variable distributions are unfolded to the charged-particle level. The b jet substructure is compared to the substructure of jets in an inclusive jet sample that is dominated by light-quark and gluon jets in order to assess the role of the b quark mass. A strong suppression of emissions at small $\textit{R}$ values is observed for b jets when compared to inclusive jets, consistent with the dead-cone effect. The measurement is also compared with theoretical predictions from Monte Carlo event generators. This is the first substructure measurement of b jets that clusters together the b hadron decay daughters independent of the b hadron species and decay channel.

S. Chatterjee

C. Caputo

I. Donertas

T. Tran

Jet fragmentation function and groomed substructure of bottom quark jets in proton-proton collisions at 5.02 TeV

A search for a pair of light pseudoscalar bosons (a ) produced in the decay of the 125 GeV Higgs boson is presented. The analysis examines decay modes where one a decays into a pair of tau leptons and the other decays into either another pair of tau leptons or a pair of muons. The a boson mass probed in this study ranges from 4 to 15 GeV. The data sample was recorded by the CMS experiment in proton-proton collisions at a center-of-mass energy of 13 TeV and corresponds to an integrated luminosity of 138 fb . No excess above standard model (SM) expectations is observed. The study combines the 4τ and 2μ2τ channels to set upper limits at 95% confidence level (CL) on the product of the Higgs boson production cross section and the branching fraction to the 4τ final state, relative to the Higgs boson production cross section predicted by the SM. In this interpretation, the a boson is assumed to have Yukawa-like couplings to fermions, with coupling strengths proportional to the respective fermion masses. The observed (expected) upper limits range between 0.007 (0.011) and 0.079 (0.066) across the mass range considered. The results are also interpreted in the context of models with two Higgs doublets and an additional complex singlet field (2HD+S). The tightest constraints are obtained for the Type III 2HD+S model. In this case, assuming the Higgs boson production cross section equals the SM prediction, values of the branching ratio for the Higgs boson decay into a pair of a bosons exceeding 16% are excluded at 95% CL for a boson masses between 5 and 15 GeV and tan $\textit{β >}$ 2, with the exception of scenarios in which the a boson mixes with charm or bottom quark-antiquark bound states.

Search for light pseudoscalar boson pairs produced from Higgs boson decays using the 4τ and 2μ2τ final states in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV