# Precision Standard Model Measurements Measurements of finalstate particles

- Slides: 37

Precision ‘Standard Model’ Measurements • Measurements of finalstate particles in welldefined fiducial regions • Generally differential cross sections • Should not (and mostly do not) assume the SM • Agree with the SM (so far) • Thus they can potentially exclude extensions June 2019 JMB, DESY 1

Key tools: • BSM Model in Feyn. Rules UFO interface June 2019 Final State Particles • New processes in Herwig 7 JMB, DESY • Rivet, and data from Hep. Data Exclusion 2

Key tools: Constraints On New Theories Using Rivet • BSM Model in Feyn. Rules UFO interface June 2019 Final State Particles • New processes in Herwig 7 JMB, DESY • Rivet, and data from Hep. Data Exclusion 3

Key tools: Constraints On New Theories Using Rivet Final State Particles CONTUR • BSM Model in Feyn. Rules UFO interface https: //contur. hepforge. org/ • New processes in Herwig 7 • Rivet, and data from Hep. Data Exclusion https: //contur. hepforge. org/ June 2019 JMB, DESY 4

Strategy • Use measurements shown to agree with the Standard Model – (Currently) assume the data = the background, as in a typical search control region. – Excellent for quick sensitivity/limit scans of new models • Key for constraining new models if there is a signal (unintended consequences) • Key for constraining scale of new physics if there is no signal June 2019 JMB, DESY 5

Dynamic data selection • Measurements of fiducial, particle-level differential cross sections, with existing Rivet routines • Classify according to data set (7, 8, 13 Te. V) and into non-overlapping signatures • Use only one plot from each given statistically correlated sample – e. g. Jets, lv+jets, ll+jets, g (+jets), gg, 4 l, etc …. • “Most sensitive measurement” will vary with model and model parameters June 2019 JMB, DESY 6

Some examples • Spontaneously-broken B-L gauge theory • Generic Light Scalar Model • Dark Matter models • Dark Energy • Flavour anomalies June 2019 JMB, DESY 7

Some examples • Spontaneously-broken B-L gauge theory • Generic Light Scalar Model • Dark Matter models • Dark Energy • Flavour anomalies June 2019 JMB, DESY 8

Spontaneously-broken B-L gauge theory S. Amrith, JMB, F. F. Deppisch, W. Liu, A. Varma, D. Yallup 1811. 11452, JHEP 1905 (2019) 154 • UV complete • Three pairs of parameters which interplay to give quite a rich phenomenology – New U(1) gauge symmetry from B-L • New gauge boson Z’, coupling g 1’ – Spontaneously broken • New Higgs boson, h 2, can mix with SM Higgs: sina – RH neutrinos with Majorana masses, natural explanation of light neutrino masses (seesaw mechanism) • Lifetime of neutrino may lead to prompt decays, (far-)displacedvertex, or effective stability for collider signatures June 2019 JMB, DESY 9

Spontaneously-broken B-L gauge theory June 2019 JMB, DESY 10

Spontaneously-broken B-L gauge theory Contur approach is not well-suited for long-lived-particle signatures: most measurements demand prompt particles attached to primary vertex, or else known SM particle (B, t…). See Deppisch, Liu, Mitra ar. Xiv: 1804. 04075 for a study of this model June 2019 JMB, DESY 11

Case A June 2019 JMB, DESY 12

Case B June 2019 JMB, DESY 13

Case C June 2019 JMB, DESY 14

Case C June 2019 JMB, DESY 15

Case D June 2019 JMB, DESY 16

Case E June 2019 JMB, DESY 17

Case D June 2019 JMB, DESY 18

Some examples • Spontaneously-broken B-L gauge theory • Generic Light Scalar Model • Dark Matter models • Dark Energy • Flavour anomalies June 2019 JMB, DESY 19

Generic Light scalars • Effective couplings to gauge bosons. – Dominant decay to photons sensitivity in inclusive, diphoton and V+photon measurements – Model from S. Fichet, G. Moreau. See Les Houches 2017 proceedings ar. Xiv: 1803. 10379, Contribution 20 June 2019 JMB, DESY 20

June 2019 JMB, DESY 21

Some examples • Spontaneously-broken B-L gauge theory • Generic Light Scalar Model • Dark Matter models • Dark Energy • Flavour anomalies June 2019 JMB, DESY 22

Simplified Dark Matter Model • Introduce Z’ mediator, a Majorana fermion DM candidate, and two couplings • Variant considered in Z’ which couples only to first generation quarks – JMB, D. Grellscheid, M. Krämer, B. Sarrazin, D. Yallup , ar. Xiv: 1606. 05296 • Have since also looked at coupling to all generations June 2019 JMB, DESY 23

Comparison to ATLAS search benchmarks ar. Xiv: 1903. 01400 June 2019 JMB, DESY 24

Comparison to ATLAS search benchmarks ar. Xiv: 1903. 01400 June 2019 JMB, DESY 25

Two Higgs-doublet model, with the pseudoscalar Higgs acting as mediator to Dark Matter ATLAS ar. Xiv: 1707. 03263 ar. Xiv: 1903. 01400 June 2019 JMB, DESY CMS ar. Xiv: 1606. 01522, 26

Some examples • Spontaneously-broken B-L gauge theory • Generic Light Scalar Model • Dark Matter models • Dark Energy • Flavour anomalies June 2019 JMB, DESY 27

Scalar Dark Energy Field coupling to SM • Mode introduced by Brax, Burrage, Englert & Spannowsky in ar. Xiv: 1604. 04299 • Neutral scalar dark energy field of mass �� couples to Standard �� Model particles via various Effective Field Theory (EFT) operators which are suppressed by powers of a scale parameter ��. ����� • Concentrate on couplings �� 1 & �� 2 which appear in front on the leading EFT operators, setting others to zero. – This means that �� is pair-produced and stable, so dominant signatures are expected to involve missing transverse energy. Setting �� 1=�� 2=1 scan in �� �� and �� ����� June 2019 JMB, DESY 28

Scalar Dark Energy Field coupling to SM • Now set �� =0. 1 Ge. V, and setting ��. �� 2=1−�� 1, scan in �� 1 and �� ����� Limits similar to but stronger than reinterpreted searches in the original paper (which used 8 Te. V data) Most sensitive measure, ATLAS 13 Te. V jets + missing energy. ar. Xiv: 1707. 03263 June 2019 JMB, DESY 29

Some examples • Spontaneously-broken B-L gauge theory • Generic Light Scalar Model • Dark Matter models • Dark Energy • Flavour anomalies June 2019 JMB, DESY 30

Flavour Anomalies • no June 2019 JMB, DESY Moriond 2019 31

Flavour Anomalies • Introduce a new particle/interaction to explain this: • Look at the impact of direct searches and measurements for such a particle • e. g. Allanach, JMB, Corbett ar. Xiv: 1904. 10954 June 2019 JMB, DESY 32

Summary… • With the Higgs, the Standard Model could work well above the Electroweak symmetry breaking scale. • Take its predictions seriously! • Model independent measurements stored in Hep. Data and Rivet are a powerful and flexible resource – Already used more MC tuning and validation, comparison to precision SM measurements – Can now be used to constrain BSM physics (several examples shown, more available) June 2019 JMB, DESY 33

Summary… • Complementary approaches – EFT fits when new states are out of reach – Truly “exotic” signatures (e. g. long lived/(dis)appearing particles etc) require dedicated searches • Future – Keep adding more data. Hopefully the priority of these kind of measurements at LHC will increase – Treat correlations better, where available – Use precision SM theory where available: Could then also become a discovery tool June 2019 JMB, DESY 34

Simplified DM model coupling to first generation quarks June 2019 JMB, DESY 35

Simplified DM model coupling to all quark flavours June 2019 JMB, DESY 36

Simplified DM model coupling to all flavours ATLAS, ar. Xiv: 1502. 05923 June 2019 JMB, DESY 37

- Standard Model for Subatomic Particles Elementary Fundamental Particles
- Particles Radioactivity and particles c Particles describe the
- Particle physics precision precision and precision or three
- Precision Measuring Precision Measuring Precision How close together
- Standard Model of Particles What is the standard