Dark Matter @ LHC 2018 (#DMLHC2018)

3 Apr 2018, 12:30 → 6 Apr 2018, 14:30 Europe/Zurich

Main lecture room (HS I) (U. of Heidelberg / KIP)

Oleg Brandt (Ruprecht Karls Universitaet Heidelberg (DE))

The Dark Matter @ LHC 2018 workshop (#DMLHC2018) takes place from April 3rd afternoon to 6th, 2018, and covers experimental and theoretical aspects of collider-based searches for dark matter. The goal of the workshop is to bring together the experimental and theory communities, to review the current status and discuss potential avenues into the future.

This agenda provides the timetable and the facilities for registration and abstract submission.

Main DM@LHC 2018 website: https://www.kip.uni-heidelberg.de/dmlhc/home.

Follow us: #DMLHC2018

The workshop poster is available here.

Please note the Satellite Workshop "Dark Matter at the Dawn of Discovery ?" which will take place in Heidelberg on 9-11 April 2018.

Poster_DM@LHC2018_Heidelberg.pdf

Tuesday, 3 April

12:30 Arrival & registration

Key channels + precision pheno: #1

Conveners: Adish Vartak (Univ. of California San Diego (US)), Caterina Doglioni (Lund University (SE)), Marek Schoenherr (CERN)

1 Welcome

Speakers: Oleg Brandt (Ruprecht Karls Universitaet Heidelberg (DE)), The organisers

2018_04_03_DMatLHC_Welcome.pdf

2 Keynote: Is the WIMP paradigm going strong? [35'+10']

Speaker: Manfred Lindner (Max Planck Institut fuer Kernphysik, Heidelberg, Germany)

lindner.pdf

3 New directions in dark matter searches from initial state radiation [20'+10']

Speaker: Zeynep Demiragli (Massachusetts Inst. of Technology (US))

dmlhc_demiragli.pdf

4 SM Background predictions at the precision frontier [20'+10']

Speakers: Jonas Lindert, Jonas Lindert, Jonas Lindert (University of Durham (GB))

JL_DMatLHC18.pdf

16:00 Coffee break

Key channels + precision pheno: #2

Conveners: Adish Vartak (Univ. of California San Diego (US)), Caterina Doglioni (Lund University (SE)), Marek Schoenherr (CERN)

5 Probing renormalisable dark matter portals at the LHC [20'+10']

Speaker: Felix Kahlhoefer (DESY)

Kahlhoefer_portals.pdf

6 Dark matter through the 125 GeV Higgs window [20'+10']

Speaker: Christian Ohm (KTH Royal Institute of Technology (SE))

slides.pdf

7 Looking for hard interactions with dark matter using SM candles [20'+10']

Speaker: Shih-Chieh Hsu (University of Washington Seattle (US))

DM_LHC.pdf

8 New directions in dijet searches [20'+10']

Speaker: Sarah Malik (Imperial College (GB))

DMLHC2018-final.pdf

Welcome reception

Wednesday, 4 April

Complex channels: #1

Conveners: Steven Lowette (Vrije Universiteit Brussel (BE)), Ulrich Andreas Haisch, Dr Valerio Ippolito (Sapienza Universita e INFN, Roma I (IT))

9 X + MET versus model-specific signatures: pros and cons

Speaker: Kai Ronald Schmidt-Hoberg (Deutsches Elektronen-Synchrotron (DE))

DMLHC_18.pdf

10 New techniques in SUSY-inspired searches

Speaker: Elvira Rossi (Universita e sezione INFN di Napoli (IT))

ERossi_DM@LHC2018.pdf

11 Shedding light on dark matter with associated heavy flavour production

Speaker: Dorival Gonçalves (University of Pittsburgh)

dorival_DM@LHC.pdf

10:30 Coffee break

Complex channels: #2

Conveners: Steven Lowette (Vrije Universiteit Brussel (BE)), Ulrich Andreas Haisch, Valerio Ippolito (Sapienza Universita e INFN, Roma I (IT))

12 Turning every stone at the LHC: diverse signatures with the 2HDM+a model

Speaker: Giacomo Polesello (INFN, Sezione di Pavia (IT))

polesello_heidelberg.pdf

13 New directions in long-lived particle searches

Speaker: Kristian Hahn (Northwestern University (US))

kristian_LLPDM_DM@LHC.pdf

14 New colliders signatures from asymmetric dark matter

Speakers: Kathryn Mary Zurek (University of California Berkeley (US)), Kathryn Zurek (Lawrence Berkeley National Lab), Kathryn Zurek (LBNL)

18_LHC_DM_Zurek.pdf

12:30 Lunch break

Low-energy / flavour searches & interplay: #1

Conveners: Florian Goertz (Max-Planck-Gesellschaft (DE)), Mitesh Patel (Imperial College (GB)), Ulrich Uwer (Ruprecht Karls Universitaet Heidelberg (DE))

15 DM needles in the low-energy+flavour haystack

Speaker: Monika Blanke

Blanke-DMLHC2018.pdf

16 Shining light on the dark sector with LHCb

Speaker: Martino Borsato (Universidade de Santiago de Compostela (ES))

DarkSectorsAtLHCb_MBorsato.pdf

17 New results on flavor anomalies at LHCb

Speaker: Paula Alvarez Cartelle (Imperial College (GB))

FlavourAnomaliesLHCb.pdf

18 Flavor anomalies and their dark side

Speakers: Nazila Mahmoudi (Universite Claude Bernard Lyon I (FR)), Nazila Mahmoudi (LPC Clermont & CERN), Nazila Mahmoudi (CERN and Lyon University (FR))

Nazila_DM-LHC_April2018.pdf

16:00 Coffee break

Low-energy / flavour searches & interplay: #2

Conveners: Florian Goertz (Max-Planck-Gesellschaft (DE)), Mitesh Patel (Imperial College (GB)), Ulrich Uwer (Ruprecht Karls Universitaet Heidelberg (DE))

19 Breaking with the WIMP paradigm: axions and dark photons

Speaker: Joerg Jaeckel (ITP Heidelberg)

20 Squeezing dark matter using precision searches for lepton flavour violation

Speaker: Prof. Niklaus Emanuel Berger (JGU Mainz)

BergerDMAtLHC.pdf

21 New directions in dark photon searches in fixed-target experiments

Speaker: Nikolai Krasnikov (Russian Academy of Sciences (RU))

Krasnikov.Heidelberg2018.pdf

22 Probing dark photons and ALPs at b-factories

Speaker: Dr Torben Ferber (DESY)

2018_04_dmlhc_ferber.pdf

Thursday, 5 April

(In-) direct searches complementarity & interpretation: #1

Conveners: Antonio Boveia (Ohio State University), Dr Christopher McCabe (King's College London), Malcolm Fairbairn

23 Direct detection + Indirect detection + colliders: complementarity & interplay

Speaker: Dr FARINALDO queiroz (Max Planck Institute for Nuclear Physics - Heidelberg)

Farinaldo_DMLHC_2018.pdf

24 Direct detection: new results from noble gas experiments

Speaker: Teresa Marrodán Undagoitia (Max-Planck-Institut für Kernphysik)

Marrodan_MPIK_DM@LHC_Apr18.pdf

25 Direct detection: new results from solid state experiments

Speaker: Dr Holger Kluck (HEPHY)

2018-04-05_DMLHC_Kluck_final.pdf

10:30 Coffee break

(In-) direct searches complementarity & interpretation: #2

Conveners: Antonio Boveia (Ohio State University), Christopher McCabe (King's College London), Malcolm Fairbairn

26 Linking LHC and direct detection results in Higgs portals

Speaker: Prof. Achim Schwenk (TU Darmstadt)

Schwenk_DM@LHC_2018.pdf

27 Indirect detection: galactic centre excess and connection to the LHC?

Speaker: Dr Anthony DiFranzo (Rutgers University)

DMLHC_GCE_DiFranzo.pdf

28 Galactic centre excess: signal or background?

Speaker: Mariangela Lisanti (Stanford University)

dm_lhc_2018.pdf

12:30 Lunch break

Open Session A): #1

Conveners: Greg Landsberg (Brown University (US)), Michael Kramer (Rheinisch Westfaelische Tech. Hoch. (DE))

29 Consistent Models of Dark Matter at the LHC

We study universal properties of dark matter models with a pseudoscalar mediator at the Large Hadron Collider. A simplified model with a second Higgs doublet and effective couplings to the dark sector is investigated.
Constraints from Higgs signal strength measurements, flavor and electroweak precision observables are considered. The remaining parameter space overlaps with a region in which the observed relic density can be reproduced. We analyze possible missing transverse energy signatures. For a large set of parameters, due to a resonant enhancement, the mono-$Z$ channel provides stronger limits than mono-jet searches. We emphasize that these mono-X searches are complementary to direct and indirect detection experiments.

Speaker: Valentin Tenorth (Max-Planck-Institut für Kernphysik)

Tenorth_Consistent.pdf

30 Search for dark matter (DM) production in association with a leptonically decaying Z boson with the ATLAS detector

We present a recent search for dark matter (DM) production in association with a leptonically decaying Z boson. The search is performed with 36.1 fb−1 of 13 TeV proton-proton collision data collected by the ATLAS experiment at the LHC. No significant excess above the SM back- ground is observed. For simplified models with vector or axial-vector mediators, including extensions to lepton couplings, 95% confidence level exclusion limits are placed on the DM and mediator masses (mχ, mmed). For the richer parameter space of 2DHDM with an additional pseudoscalar mediator, exclusion limits are produced for the light pseudoscalar mass (ma), the heavy scalar and pseudoscalar masses (mH, mA), and on the ratio of the vacuum expectation values (tan β).

Speaker: Christopher Ryan Anelli (University of Victoria (CA))

DMLHC2018_ChrisAnelli.2.pdf

31 Search for Dark Matter in association with a hadronically decaying Z' vector boson with the ATLAS detector

A search for dark matter pair production in association with a Z' boson in
pp colisions, at 13 TeV, using 36.1fb-1 data, recoreded with the ATLAS
detector is presented. Events are characterised by large missing transverse
momentum and a hadronically decaying vector boson reconstructed as either a
pair of small-radius jets, or as a single large-radius jet with substructure.
Results are interpreted in terms of simplified models which describe the
interaction of dark matter and standard model particles.

Speaker: Sarah Louise Barnes (Shanghai Jiao Tong University (CN))

DM@LHCTalk16.pdf

32 Mono-X Signals from Initial States and Decays

Mono-X processes provide promising channels for DM searches at the LHC. Two types of topologies for these processes are initial state X-radiation and decays in the final state. For ISR, I will consider a Z'-mediator toy model and argue that mono-jet is the most promising ISR channel. This motivates studying final state decays for mono-Z, mono-h, and di-h processes. To this end, I will use the MSSM as a WIMP framework. In particular, I will focus on how these processes are constrained by direct detection and the DM relic abundance. Thereby, I will argue that direct detection limits favor di-h over mono-h. I will further show how these constraints can be ameliorated in the NMSSM. Finally, I will compare our findings to existing EFT results.

Speaker: Elias Bernreuther (Heidelberg University)

monox_eliasbernreuther.pdf

33 Search for dark matter in the channel of Mono-H($\gamma\gamma$) at the ATLAS experiment and truth-level reweighting

A search for dark matter in association with a Higgs boson decaying to two photons based on 36.1 fb$^{-1}$ data collected with the ATLAS detector at the LHC at the energy of 13 TeV will be presented. No significant excess over the expected background is observed. Upper limits at 95% confidence levels are set for the Standard Model Higgs boson decaying into two photons in association with missing transverse momentum in different benchmark models: a baryonic Z' model and a two-Higgs-doublet-model with a Z' boson. A method of truth-level reweighting is applied in this analysis. The acceptances of the samples after kinematic cuts agree well, and the residual difference is treated as an extra systematic uncertainty in the signal yield.

Speaker: Kristian Bjoerke (University of Oslo (NO))

kbjorke-DMLHC2018-180405.pdf

34 Hunting the dark Higgs

I discuss a novel signature of DM production at the LHC resulting from an additional Higgs boson in the dark sector, whose presence is motivated by the need to generate the masses of the dark sector particles and the possibility to relax constraints from the DM relic abundance by opening up a new annihilation channel. If the dark Higgs boson decays into SM states via a small mixing with the SM Higgs boson, one obtains characteristic large-radius jets in association with missing transverse momentum that can be used to efficiently discriminate signal from backgrounds. I present the sensitivities achievable in LHC searches for dark Higgs bosons and show that they can probe regions of parameter space inaccessible to mono-jet or di-jet searches.

Speaker: Michael Duerr (DESY)

Duerr_DMLHC2018.pdf

35 Interpretation of searches for Dark Matter produced in association with a hadronically decaying Standard Model boson at ATLAS

After a brief review of the searches for Dark Matter produced in association
with the Standard Model electroweak gauge or Higgs bosons from the ATLAS
experi- ment, exclusion limits with reduced model dependence will be
presented for each of them. Their impact on the allowed parameter space of
the 2HDM+a model will be compared with the direct interpretation in the
context of this model.

Speaker: Stanislav Suchek (Ruprecht Karls Universitaet Heidelberg (DE))

ssuchek_dmatlhc2018.pdf

36 The h(bb) + missing transverse momentum signature in the 2HDM + pseudoscalar simplified model

The two-Higgs-doublet model with an additional pseudoscalar represents a simplified and ultraviolet-complete model for Dark Matter. It provides a wide spectrum of collider signatures, including a $Z$ or a Higgs boson and missing transverse momentum, with detectable cross-sections at the LHC. In the context of this model, the sensitivity of an existing search of the ATLAS experiment for the signature of a $125$ GeV Higgs boson decaying to two b quarks and missing transverse momentum from Dark Matter particles is discussed. The exclusion potential is estimated using simplified detector-level limits previously published by the ATLAS Collaboration.

Speaker: Lars Henkelmann (Ruprecht Karls Universitaet Heidelberg (DE))

2HDMa_MonoHbb_LHenkelmann_05042018_DMatLHC.pdf

Open Session B): #1

Conveners: Michel Tytgat (Université Libre de Bruxelles), Oliver Buchmuller (Imperial College (GB))

37 Disappearing charged tracks for compressed Dark Sectors

While the LHC "mono-X" like searches have a mild (few 100 GeVs) reach for WIMPs due to the small EW cross section and the large V+jets backgrounds, models where dark matter is mostly part of a weak multiplet (Minimal Dark Matter) can be probed via the long-livedness of the electrically charged members of the multiplet. Using the benchmark-case of a weak doublet (pure-Higgsinos in SUSY) I will show how this searches can extend the mass reach at both the LHC and the FCC, provided that one can be sensitive to decay lengths of 10 cm, as possible with the current ATLAS 4-pixel layer setup.I will also discuss the prospects to test the same model with a novel strategy at future electron-proton colliders.

Speaker: José Francisco Zurita (KIT)

Zurita_DM_at_LHC2018.pdf

38 Long-lived particles within the dark sector: promising signatures for dark matter searches at LHC

Many dark matter models predict monojet signatures at colliders. However, if the dark sector also contains long-lived particles, less conventional signatures can arise. In this talk I will discuss this possibility by considering two different models: the "pseudo-Dirac model", which predicts displaced vertices, and the "chromo-electric dipole model", which is characterized by composite states referred to as R-hadrons, analagous to those in supersymmetry. In both cases, these unusual signatures can be complementary, or even competitive, with standard searches.

Speaker: Alessandro Davoli

Davoli_DM_LHC.pdf

39 Long Lived Particles and Dark Photons at LHCb

Recent results are presented on searches at LHCb for both prompt-like and long-lived dark photons, produced in proton-proton collisions at a center-of-mass energy of 13 TeV, using decays into two muons. A search for long-lived particles with a mass between 25 and 50 GeV/c² and a lifetime between 2 and 500 ps is presented as well, where the signature is a single long-lived particle identified by a displaced vertex with two associated jets.

Speaker: Carlos Vazquez Sierra (Nikhef National institute for subatomic physics (NL))

CVS_DMLHC_v3.pdf

40 Constraining simplified models of dark matter with searches for long-lived charged particles

We introduce a new class of simplified models to address the effects of 3-point interactions between the dark matter particle, its dark co-annihilation partner, and the Standard Model degree of freedom, which we take to be the tau lepton. We investigate these effects as well as the discovery potential for dark matter co-annihilation partners at the LHC. A small mass splitting between the dark matter and its partner is preferred by the co-annihilation mechanism and suggests that the co-annihilation partners may be long-lived (stable or meta-stable) at collider scales. It is argued that such long-lived electrically charged particles can be looked for at the LHC in searches of anomalous charged tracks.

Speakers: Alexis Plascencia (Durham University), Dr Kazuki Sakurai (University of Warsaw)

Plascencia_DM@LHC.pdf

41 Diffractive Production of Missing Mass in Cosmic Ray Air Showers above 10 PeV

Besides for the LHC, also for modelling of the development of the
Cosmic Ray (CR) Air Showers, diffractive processes need to be studied.
Dark Matter (DM) is assumed to be produced in hadronic interaction.
In the transverse shower plane on ground the incoming muons from Air
Showers add to zero 3-momentum. A large area Muon Detector, located
within the KASCADE-Grande Air Shower experiment, has been built with
the aim to identify muons and their directions in Air Showers from 1-15
PeV. Muon pseudorapidity distributions for the first interaction of
the Cosmic Ray particles above 10000 m are studied and compared to Monte
Carlo simulations. Un-balanced 3-momentum of muons in the shower plane
on ground is observed for Air Showers above 10 PeV.

Speaker: Paul Doll (KIT-Karlsruhe)

Doll-dark-matter-talk-5-4-2018-3.pdf

42 Hunting All the Hidden Photons

We explore the full constraining power of experimental bounds derived for hidden photons by applying them to gauge bosons of a weakly coupled $U(1)_{B-L}$, $U(1)_{L_\mu-L_\tau}$, $U(1)_{L_\mu-L_e}$ and $U(1)_{L_\tau-L_e}$. The associated gauge bosons of these anomaly-free groups are well-motivated mediators to a dark sector. In contrast to a hidden photon that acquires universal couplings to charged SM particles through kinetic mixing with the photon, several SM particles are uncharged under these gauge groups. Also taking into account loop-induced kinetic mixing the hidden photon bounds are drastically altered for the different gauge groups. We also discuss cosmological constraints and the sensitivity of future experiments.

Speaker: Patrick Foldenauer

hidden_photons_pf.pdf

43 Searching for Dark Photons with SuperCDMS

The Super Cryogenic Dark Matter Search (SuperCDMS) is a direct dark matter search experiment designed to observe nuclear recoils induced by WIMPs. However, it is also sensitive to dark photons, producing an electron recoil signature. SuperCDMS uses cryogenic detectors in two configurations: one has an excellent capability to discriminate between electron and nuclear recoils, while the other significantly lowers the energy threshold. The latter configuration provides sensitivity to new parameter space at dark photon masses of a few tens of eV to about 1 keV. This talk will highlight the ongoing dark photon search with data from SuperCDMS Soudan, and will discuss the prospect of a search with the upcoming SuperCDMS SNOLAB experiment.

Speaker: Dr Belina von Krosigk (University of British Columbia)

2018_DMatLHC_BvKrosigk_v1.pdf

44 Radiate Neutrino masses, keV-scale DM and viable Leptogenesis via sub-TeV new physics

This work is based on the so-called Scotogenic model which enhances the Standard Model with a second Higgs doublet and three right-handed neutrinos as gauge singlets. An additional Z_2 symmetry is proposed under which all new particles are charged.

This allows for a stable DM candidate in the keV-range and a radiative generation of active neutrino masses. Also I want to address the question of baryogenesis in this model framework. A baryon asymmetry is generated via sub-TeV Leptogenesis which incorporates lepton number conserving oscillations among the RH neutrinos and lepton number violating decays of the second Higgs doublet.

Speaker: Sven Baumholzer

DMLHC_Baumholzer.pdf

Open Session C): #1

Conveners: Mario Martinez-Perez (Universitat Autonoma de Barcelona (ES)), Pedro Klaus Schwaller (Mainz University)

45 CMS results in final states with a photon and missing transverse momentum

A search is conducted for new physics in final states containing a photon and missing transverse momentum in proton-proton collisions at sqrt(s) = 13 TeV. The data collected by the CMS experiment at the CERN LHC correspond to an integrated luminosity of 35.9 inverse femtobarns. The results are interpreted as exclusion limits on the various dark matter models, such as heavy vector mediators, dimension-7 contact operators, and Higgs-portal dark sectors. Improved limits are set with respect to previous analyses using photon plus missing transverse momentum final states.

Speaker: Brandon Leigh Allen (Massachusetts Inst. of Technology (US))

BAllen_DM@LHC2018_Monophotonv2.pdf

46 Leptophilic dark matter from gauged lepton number: Phenomenology and gravitational wave signatures

In this work, we consider a model in which the SM gauge group is extended by a lepton number $U(1)_L$. The arising gauge anomalies are canceled by adding two sets of SM vector-like leptons. We further add a scalar field that spontaneously breaks $U(1)_L$. An accidental global symmetry ensures the stability of the lightest additional lepton, thus providing a dark matter candidate. We investigate current and future constraints on the model from collider searches as well as dark matter experiments. We further study the EWSB and $U(1)_L$ breaking phase transitions, particularly focusing on the potential for generating gravitational wave signatures that are accessible to GW interferometry as a complementary way to probe the model.

Speaker: Mr Eric Madge (Johannes Gutenberg University Mainz)

Leptophilic_Dark_Matter_from_Gauged_Lepton_Number-Eric_Madge.pdf

47 CMS combined tt+DM search with 2016 data

Dark matter production in association with a top quark pair is widely considered the most direct probe of spin-0 mediated dark matter production. A search for tt+DM which incorporates all major decay modes and the first statistical combination of these channels using 35.9/fb collected by the CMS detector in 2016 is presented. The result is the most stringent constraint to date on spin-0 mediated tt+DM, covering significant parameter space and uniquely presented in the mass-mass and couplings-mass planes. The limits set on the scalar mediator are also the strongest result for a collider dark matter search in any final state.

Speaker: Stanislava Sevova (Northwestern University (US))

ttdm_dmatlhc_ssevova.pdf

48 Characterisation of the NLO cross sections for the associated production of dark matter with heavy quarks

Searches for dark matter produced in association with heavy quarks using collider data are starting to probe an interesting region of the parameter space, becoming quickly competitive with more traditional searches. Higher order corrections provide a sizeable impact on the total production rate of these models. In this proceedings we study the dependence of the next-to-leading order cross sections on the PDF and renormalisation and factorisation scales choices. Furthermore we address for the first time the dark matter production with bottom quarks scenario, proposing a final recommendation for the cross section calculation of this final state.

Speakers: Yoav Afik (Technion- Israel Institute of Technology (IL)), Yoram Rozen (Technion- Israel Institute of Technology (IL)), Marco Zaro (Nikhef National institute for subatomic physics (NL))

DM@LHC 2018.pdf

49 Resonance Searches with B-jets in the Final States with the ATLAS Detector

Many BSM models with enhanced couplings to third generation fermions have been proposed to incorporate the persistent anomalies observed in flavor physics experiments. Resonance searches with b-jets in the final states provide excellent opportunities to probe this scenario. A search for di-jet resonances with one or two jets identified as b-jets in proton-proton collisions at sqrt = 13 TeV collected with the ATLAS detector is discussed in detail. In addition, an ongoing search for similar resonances produced in association with extra b-jets is introduced.

Speaker: Bingxuan Liu (Argonne National Laboratory (US))

DM@LHC_BJetResonanceSearch_ATLAS_BingxuanLiu.pdf

50 An exceptional composite dark matter candidate

Models of composite Higgs provide a natural explanation of the hierarchy problem and a beautiful rationale for the flavor puzzle. However, they typically lack a natural DM candidate unless non-minimal setups with symmetric cosets are considered. Here, I will show an example of a non-symmetric coset - SO(7)/G2 - which nevertheless provide dark pions as viable DM candidates (a scalar SU(2)L singlet or a triplet) and studied in detail their phenomenology. The relic density, as well as the expected indirect, direct and collider signals are then uniquely determined by the value of the compositeness scale, providing therefore an extremely predictive framework. This proves that non-symmetric cosets has to be considered when charting DM models.

Speaker: Adrian Carmona Bermudez (Johannes Gutenberg Universitaet Mainz (DE))

heidelberg.pdf

51 Search for dark matter produced in association with bottom or top quarks in √s=13 TeV pp collisions with the ATLAS detector

A wide search program is being carried on at the LHC under the hypothesis that Dark Matter (DM) consist of weakly interacting massive particles (WIMPs). Final states with heavy flavour quarks and large momentum imbalance represent an interesting discovery signature which allows to probe models with scalar or pseudoscalar interactions between the Standard Model and the Dark Sector under the assumption of Minimal Flavour Violation. We will present the most recent results of searches for DM produced in association with a pair of heavy flavour quarks (DM+HF) in ATLAS based on 36.1 fb-1 of proton-proton collision data collected at a centre of mass energy of 13 TeV.

Speaker: Marco Rimoldi (Universitaet Bern (CH))

DM@LHC_MRimoldi.pdf

52 Search for dark matter in association with a tt pair at sqrt(s) = 13 TeV in the dilepton channel with the CMS experiment

A search is performed for dark matter produced in association with tt pairs in data from proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC. The data correspond to 35.9 fb-1 collected with the CMS detector in 2016. The analysis looks for an excess of events with large imbalance in transverse momentum and a top quark pair. The results are interpreted in the context of simplified models of dark matter production. Assuming unitary coupling values to standard model (SM) particles g_q, and dark matter (DM) particles g_chi, and DM mass m_chi = 1 GeV, the observed (expected) 95% CL exclusions for a scalar mediator are m_phi < 55 (73) GeV, while no exclusion is expected or observed at 95% CL for the pseudoscalar mediators.

Speaker: Juan Garcia Ferrero (Universidad de Cantabria (ES))

DMLHC_JFerrero.pdf

16:00 Coffee break

Open Session A): #2

Conveners: Greg Landsberg (Brown University (US)), Michael Kramer (Rheinisch Westfaelische Tech. Hoch. (DE))

53 Prospects of Higgs portal DM models at future colliders

My talk will base on Higgs portal DM models with fermion, vector and scalar DMs.
I will show that the LHC is unable to probe any parameter space of these models. On the other hand, in terms of four benchmark points, those model will be not only probable but also distinguishable at 500 GeV electron-positron collider and 100 TeV proton-proton collider.

Speaker: Jinmian Li (KIAS)

DMspin.pdf

54 Jet substructure tools for probing low-mass hadonic resonances at ATLAS

Many extensions of the Standard Model predict resonances with significant couplings to quarks and gluons, including resonances which also couple to dark matter particles. Such hadronic resonances
has been probed well into the TeV range at LHC. Therefore, focusing on the searches for low mass resonances is crucial for the completeness of the diet resonance searches. In order to suppress the large multijet background in the low mass region, jet substructure
tools are carrying great importance. ATLAS uses several jet substructure techniques in order to improve the sensitivity of these searches. These techniques and their impact on these searches will be presented

Speaker: Merve Sahinsoy (Ruprecht-Karls-Universitaet Heidelberg (DE))

DM@LHC_MerveSahinsoy.pdf

55 CMS searches for dark matter in events with highly-boosted resonances, using substructure and b-tagging techniques

Searches for dark matter are conducted in events with highly boosted, hadronically decaying heavy resonances. The searches isolate final states containing large missing transverse energy or containing a beyond-Standard Model resonance. These studies are performed using proton-proton collisions at a center-of-mass energy of 13 TeV, in data recorded by the CMS detector in 2016 at the LHC, corresponding to an integrated luminosity of 36/fb. New substructure and b-tagging techniques are utilized to identify the decay products of top quarks, Higgs bosons, or BSM resonances. With no significant excesses observed, results are interpreted as limits on various models.

Speaker: Siddharth M Narayanan (Massachusetts Inst. of Technology (US))

narayanan_180405_v1.pdf

56 Probing the Pseudoscalar portal to Dark Matter: From the LHC to the Galactic Centre Excess

I will propose a new search for dark matter at the LHC, characteristic of scenarios beyond the Standard Model with a pseudoscalar portal between the dark and visible sectors. This search explores large regions of parameter space that are not probed by missing energy signatures, searches for new scalars and flavour bounds. I will also show how this search could be used to test the dark matter origin of the gamma-ray Galactic Centre excess with LHC Run 2 data.

arXiv:1705.09670 [hep-ph]

Speaker: Patrick Tunney (King's College London)

TunneyDMLHCv2.pdf

57 Search for dark matter mediators using a Trigger-Object Level Analysis with the ATLAS detector

WE present a dijet resonance search, where a resonance may be an indicator of a dark matter mediator. However, the very high luminosity at the LHC has lead to high trigger thresholds that throttle the search at mediator masses below 1 TeV using conventional data taking techniques. A technique, known as the Trigger-Object Level Analysis, has been developed to lift this limitation. The technique achieves this by saving only final-state objects at trigger level, thus occupying a tiny amount of bandwidth and enabling the use of lower threshold triggers to record a high rate of events. I will be presenting the most recent results for the search for dark matter mediators and hadronic dijet resonances using this technique.

Speaker: Claire Antel (Ruprecht Karls Universitaet Heidelberg (DE))

dmatlhc_heidelberg_CAntel_05042018_final.pdf

58 LHC sensitivity for non-thermalised hidden sectors

I will discuss how event rates at the LHC can be compared to
reaction rates in the early Universe in a model-independent way. This
approach makes it possible to demonstrate that hidden sectors that never
reach thermal equilibrium in the early Universe are also inaccessible
for the LHC. The conclusion is that any particle that can be produced at
the LHC must either have been in thermal equilibrium with the Standard
Model at some point or must be produced via the decays of another hidden
sector particle that has been in thermal equilibrium.

Speaker: Felix Kahlhoefer (DESY)

Kahlhoefer_nonthermal.pdf

59 No talk

Open Session B): #2

Conveners: Michel Tytgat (Université Libre de Bruxelles), Oliver Buchmuller (Imperial College (GB))

60 Search for the Lepton Flavour Violating decay B->emu

Recent hints of lepton flavour universality violation motivate searches
for lepton flavour violating B decays.
The LHCb experiment is particularly suited for these searches due to its
large acceptance,
high trigger efficiencies and excellent tracking and particle
identification capabilities.
Recent results from LHCb on searches for the lepton flavour violating
decays B(s)->emu will be presented.

Speaker: Guido Andreassi (EPFL - Ecole Polytechnique Federale Lausanne (CH))

b2emu_dm_at_LHC_04_2018.pdf

61 Dark sector searches at BESIII

The BESIII experiment, a low-energy high-intensity frontier running in
tau-charm energy region, provides good opportunity for the search of
the exotic particles predicted in new physics models in dark sector scenario.
Using data samples taken at the peak of J/psi, and psi(3770), some of the
highlights including the search for the dark photon using initial state radiation
reactions process and in J/psi decays, the search for invisible decays of
eta and etaprime will be presented

Speaker: Yuping Guo

BESIII_DarkSector_YPGuo_DMLHC2018.pdf

62 Dark Matter Bound States

Dark Matter might be an accidentally stable baryon of a new confining gauge inter- action. I will explore the possibility that the DM is made of dark quarks. The resulting phenomenology contains new unusual elements: a two-stage DM cosmology, a large DM annihilation cross section through recombination of dark quarks. Light dark glue-balls are relatively long lived and give extra cosmological effects; DM itself can remain radioactive up to the present day, leading to new signals. The new confining sector leads to new resonances, which can be searched for at the LHC. Those can have long live times and get accumulated in the LHC. Thus these models provides an excellent example of the complementarity of collider, direct and in-direct searches.

Speaker: Juri Smirnov (Universita e INFN, Firenze (IT))

DM@LHC2018.pdf

63 Directional Search for Dark Matter Using Nuclear Emulsion

The NEWSdm experiment, based on nuclear emulsions, is a new experiment proposal intended to measure the direction of WIMP-induced nuclear recoils with a solid-state detector, thus with a high sensitivity. We discuss the discovery potential of a directional experiment based on the use of a solid target made of newly developed nuclear emulsions and novel read-out systems achieving nanometric resolution. We also report results of a technical test conducted in Gran Sasso.

Speakers: Andrey Alexandrov (Universita e sezione INFN di Napoli (IT)), Andrey Alexandrov (INFN sez. di Napoli)

DM@LHC2018-AAlexandrov_v2.pdf

DM@LHC2018-AAlexandrov_v2.pptx

64 Testing conversion-driven freeze-out at the LHC

Chemical equilibrium is a commonly made assumption in the freeze-out calculation of coannihilating dark matter. We explore the possible failure of this assumption and find a new conversion-driven freeze-out mechanism. Considering a representative simplified model we find regions in parameter space with very small couplings accommodating the measured relic density. In this region freeze-out takes place out of chemical equilibrium and dark matter self-annihilation is thoroughly inefficient. Due to the small dark matter coupling the parameter region is immune to direct detection but predicts an interesting signature of disappearing tracks or displaced vertices at the LHC.

Speaker: Dr Stefan Vogl (MPIK)

conversion_driven.pdf

65 Extended Dark Matter EFT

We propose a hybrid framework in the form of an effective theory, including both the dark matter states and a mediator connecting the former to the Standard Model fields. The framework overcomes the problems of traditional DM-EFT regarding the validity at high energies at collider experiments and improves the generality of the simplified models.

For fermionic and scalar dark matter with a (pseudo-)scalar mediator, the leading effects originate from dimension-five operators, allowing to capture them with a rather small set of new couplings.

The correlations between constraints from reproducing the correct relic density, direct-detection experiments, and mono-jet and Higgs + missing energy signatures at the LHC are analysed.

Speaker: Tommi Alanne (MPIK Heidelberg)

eDMEFT.pdf

66 No talk

Open Session C): #2

Conveners: Mario Martinez-Perez (Universitat Autonoma de Barcelona (ES)), Pedro Klaus Schwaller (Mainz University)

67 Dark Matter in Association with a Single Top

Dark matter scenarios with spin-0 mediators in the s-channel have be tested in well-established processes with missing energy, such as top-pair- and mono-jet-associated production. We suggest electroweak single top production in association with a dark matter pair as an alternative channel. Based on a realistic analysis for the LHC at 13 TeV, we demonstrate how to discriminate between the signal and Standard-Model background using event kinematics. With 300 fb$^{−1}$ (3 ab$^{−1}$) of data, on-shell scalar mediators with a coupling strength gSt = 1 to top quarks can be probed up to masses of 180 (360) GeV. Single-top-associated dark matter production should thus be included as an independent search channel in the LHC dark matter program.

Speaker: Jennifer Thompson (ITP Heidelberg)

thompson_tDM.pdf

68 Dark matter production in association with a single top-quark at the LHC in a two-Higgs-doublet model with a pseudoscalar mediator

The sensitivity of the LHC experiments to the associated production of dark matter with a single top is studied in the framework of an extension of the standard model featuring two Higgs doublets and an additional pseudoscalar mediator. It is found that the experimental sensitivity is dominated by the on-shell production of a charged Higgs boson. Dedicated selections considering one and two lepton final states are developed to assess the coverage in parameter space for this signature at a centre-of-mass energy of 14 TeV. It is found that this novel signature highly complements the parameter space coverage of the mono-Higgs, mono-Z and tt+Emiss signatures considered in previous publications for this model.

Speaker: Priscilla Pani (CERN)

DMatLHC2018_singletop.pdf

69 Search for electroweak production of supersymmetric states in scenarios with compressed mass spectra at √s=13 TeV with ATLAS

Dark matter coannihilation via species with only electroweak interactions is generically realised in the MSSM. Key benchmarks include a Higgsino-dominated LSP, or a bino LSP coannihilating with winos or sleptons that are nearby in mass. Hadron collider probes of these compressed scenarios are only recently surpassing nearly two-decade-old LEP limits. A search strategy is presented that opens new sensitivity to these challenging regimes using an ISR boost and soft lepton reconstruction down to 4 GeV - among the lowest used by ATLAS.

Speaker: Jesse Liu (University of Oxford)

DM@LHC_JesseLiu_5Apr2018.pdf

70 Perspectives of monojet searches at the LHC on supersymmetric Dark Matter

The impact of the current searches at the LHC for monojets is compared to the current limits from direct searches for dark matter (DM) in the framework of the NMSSM. The DM annihilation cross section is ten orders of magnitude larger than limits on the scattering cross section. This can be explained, if the interactions are predominantly due to Higgs exchange, since the Higgs boson couples only weakly to the light quarks inside nuclei. The LHC limits cannot be visualized by a single exclusion contour in the usual cross section versus LSP mass plot in Supersymmetry, but the excluded points scatter, sometimes even below the neutrino floor from the diffuse neutrino background, a region hard to investigate by direct searches.

Speaker: Dr Conny Beskidt (KIT)

Beskidt_LHCDM_Heidelberg_2018.pdf

71 Searching for new physics in events with an energetic jet and large missing transverse momentum with the ATLAS detector

The search for new physics in events with an energetic jet and large missing transverse momentum in the final state plays a major role in the physics program of the ATLAS experiment. This experimental signature is sensitive to a large spectrum of beyond the Standard Model theories including the production of weakly interacting Dark Matter candidates. In this context the most updated results based on $36 \text{fb}^{-1}$ data collected at the center of mass energy of 13 TeV with the ATLAS detector at the LHC are shown and an outlook of the future prospectives of the analysis is addressed.

Speaker: Giuliano Gustavino (University of Oklahoma (US))

DM@LHC2018.pdf

72 Can we discover a light singlet-like NMSSM Higgs boson at the LHC?

In the next-to minimal supersymmetric standard model (NMSSM) an additional singlet-like Higgs boson with small couplings to the standard model (SM) particles is introduced. Although the mass can be well below the discovered 125 GeV Higgs boson its small couplings may make a discovery at the LHC difficult.
We use a novel scanning technique to efficiently scan the whole parameter space and determine the range of cross sections and branching ratios for a light singlet-like Higgs boson below 125 GeV.
This allows to determine the perspectives for the future discovery potential at the LHC. Specific LHC benchmark points are proposed. A discovery of such a light Higgs singlet would strongly point to a singlino as a dark matter candidate.

Speaker: Prof. Wim de Boer (KIT)

deBoer_DMLHC-HD_2018.pdf

73 Searching for dark matter with detector-corrected observables at ATLAS

A new detector-independent search for dark matter in pp collisions at 13 TeV in final states with jets and missing transverse energy using the ATLAS experiment will be presented. The measured quantity is the cross-section ratio between the production of jets in association with missing transverse energy and the production of jets in association with an opposite-sign same-flavour lepton pair. This ratio, corrected for detector resolution and efficiency effects and measured differentially with respect to a number of kinematic properties of the missing transverse energy plus jets system, allows competitive limits to be set on a wide range of dark matter models.

Speaker: Rebecca Hayley Pickles (University of Manchester (GB))

RebeccaPickles_DM@LHC2018.pdf

19:30 Workshop dinner

The workshop dinner will take place at the Kulturbrauerei (http://www.heidelberger-kulturbrauerei.de/en/), a restaurant with a microbrewery in the the old city centre.

Friday, 6 April

Experiment & theory: the future: #1

74 Cosmic Dawn, Dark Matter, and Implications for Collider-Based Searches

Speaker: Anastasia Fialkov (Harvard)

Fialkov.pdf

75 Expect the unexpected: future directions in LLP searches

Speaker: Tien-Tien Yu (CERN)

DMatLHC-Heidelberg_April2018.pdf

76 Dark Matter interpretation of the neutron decay anomaly

Speaker: Benjamin Grinstein (Univ. of California San Diego (US))

Grinstein.pdf

Grinstein.pptx

10:30 Coffee break

Experiment & theory: the future: #2

77 Follow-up: Key channels + precision pheno

Speakers: Adish Vartak (Univ. of California San Diego (US)), Caterina Doglioni (Lund University (SE)), Marek Schoenherr (CERN)

DM@LHC - Discussion session 1.pdf

78 Follow-up: Complex Channels

Speakers: Steven Lowette (Vrije Universiteit Brussel (BE)), Ulrich Andreas Haisch, Valerio Ippolito (Sapienza Universita e INFN, Roma I (IT))

dmatlhc2018.pdf

DMLHC18.pdf

Lowette_DMatLHC_ComplexChannels.pdf

79 Follow-up: Low Energy / Flavour Searches & Interplay

Speakers: Florian Goertz (Max-Planck-Gesellschaft (DE)), Mitesh Patel (Imperial College (GB)), Ulrich Uwer (Ruprecht Karls Universitaet Heidelberg (DE))

DMLowE.pdf

80 (In-)Direct Searches Complementarity + Interpretation

Speakers: Antonio Boveia (Ohio State University), Christopher McCabe (King's College London), Malcolm Fairbairn

DDIDsessionv2.pdf

81 Follow-up: Open Session A)

Speakers: Greg Landsberg (Brown University (US)), Michael Kramer (Rheinisch Westfaelische Tech. Hoch. (DE))

DM@LHC-2018-GroupA.pdf

82 Follow-up: Open Session B)

Speakers: Michel Tytgat (Université Libre de Bruxelles), Oliver Buchmuller (Imperial College (GB))

Summary-Session B.pptx.pdf

83 Follow-up: Open Session C)

Speakers: Mario Martinez-Perez (Universitat Autonoma de Barcelona (ES)), Pedro Klaus Schwaller (Mainz University)

OpenC1_Schwaller.pdf

84 Farewell

Speaker: Oleg Brandt (Ruprecht Karls Universitaet Heidelberg (DE))

2018_04_03_DMatLHC_Welcome.pdf

13:00 Departure