MULTIPURPOSE MONOJETS AT THE LHC: DARK MATTER & NEUTRINOS

Transcription

1 MULTIPURPOSE MONOJETS AT THE LHC: DARK MATTER & NEUTRINOS Ian M. Shoemaker Los Alamos February 23, 2012 [arxiv: ] w/ Alex Friedland, Michael Graesser, and Luca Vecchi [arxiv: ] w/luca Vecchi 1

2 Monojets and direct detection, only 90 o apart g makes event visible at a collider DM DM time DM time DM Birkedal, Matchev, Perelstein (2004) Beltran, Hooper, Kolb, Krusberg, Tait (2010) Goodman, Ibe, Rajaraman, Shepherd, Tait, Yu (2010) Bai, Fox, Harnik (2010) Rajaraman, Shepherd, Tait, Wijanco (2011) Fox, Harnik, Kopp, Tsai (2011)... 2

3 The LHC and Direct detection on one plot Fox, Harnik, Kopp, Tsai [ ] -Bounds are fantastic. -But what if we see something? 3

4 Missing energy DM? At the LHC, nobody knows you re dark matter. 4

5 Dark Matter Fakes j p p MET=? Easy to cut out SM produced neutrinos. But what about neutrinos with non-sm interactions? arxiv: w/ Alex Friedland, Michael Graesser, and Luca Vecchi 5

6 Generalizing Fermi L NSI = 2 2G F fp αβ (ν αγ ρ ν β )(fγ ρ Pf) Neutrino Flavor f =SM fermion P=L,R Laid the foundation for the MSW effect and pointed out that NSI can modify neutrino propagation. 6

7 Solar Neutrinos and the LHC: a UV-IR duality? ε 0.05 Recently, both SNO and 1.0 Super-K lowered 0.8 thresholds to discover PΝ e Ν e MSW NSI the MSW upturn: neither see it E Ν MeV Borexino recently targeted 8B neutrinos and also found no evidence. Combined >2σ discrepancy. Palazzo [arxiv: ] 7

8 Not all MET is created eual Jets + MET searches can bound many invisible things, like ADD gravitons, DM, (sterile) neutrinos, unparticles. 1) Yet, only SM neutrinos can interfere with the SM: σ(pp/pp j+met) = σ SM + σ int + 2 σ NSI 2) SM neutrinos have nonzero electroweak charge. 8

9 An aside: monojets provide strongest bounds on some epsilons. 9

10 Tevatron and LHC constraints on NSI L NSI = 2 2G F fp αβ (ν αγ ρ ν β )(fγ ρ Pf) diagonal off-diagonal Most stringent bounds to date on electron and tau-type NSIs. E.g. previously ε ee ur < 0.7 from DIS at CHARM (Davidson et al., 2003). 10

11 Multileptons vs. monojets NSI also produce... ν ν W l α l β W + Not as constraining as monojets. With 2.1 fb 1 N 4 =0.9 ε up αα 0.17 [ATLAS-CONF ] 2 - Needs very high luminosity (~10 fb -1 ) to compete with monojets. - Clean lepton final states offer a probe on NSI with different systematics than monojets. 11

12 Part Two: Dark Matter 12

13 Validity of an Effective Description If new physics become relevant at some high energy scale, it effects will be encoded in some high-dim operator(s), e.g. O = γµ Xγ µ X Λ 2 When E Λ, other operators become important and our effective description breaks down. Can we be more rigorous than E Λ? 13

14 Im(a J ) Partial-wave unitarity Re(a J ) physical M = 16π j (2j + 1) P j (cos θ) a J (s) Unitarity: (Re(a J )) 2 +(Im(a J ) 1/2) 2 1/4 E.g. Higgs mass (Lee, Quigg, Thacker 1977) W + W W + W m h 8π 5 2G F 780 GeV 14

15 Effective dark matter interactions Assume heavy particles can be integrated out: O = γµ Xγ µ X Λ 2 M( XX) =2 N c s Λ 2 Unitarity implies: Λ 2 TeV Whereas monojets reuire: Λ 700 GeV 15

16 Unitarity vs. Monojets DMnucleon cross section ΣSI cm TeV Monojets 7 TeV Unitarity 14 TeV Monojets 14 TeV Unitarity (universal uark couplings) DAMA CoGeNT CRESSTII XENON m X GeV In the contact limit, monojets do not provide constraints stronger than unitarity. The mediator of DAMA/CoGeNT interactions cannot be integrated out at the LHC! 16

17 Going on-shell DM DM φ DM DM How do LHC bounds change? 17

18 Accessible Z s With a Z coupling to DM and a single uark flavor there are 4 parameters in the full parameter space: mx,m Z, g X g, Γ Z light DM light Z g g Z Z X X σ g 2 g 2 X σ g 2 BR Z XX 18

19 Besting the LHC from beyond the grave m Z 2 m X Soft cuts are good 1.0 for light particles. gd gx ATLAS CDF m Z' 100 GeV m Z' 500 GeV m X GeV 19

20 Light mediators weaken monojet bounds + = where ATLAS 10.0 overtakes CDF 5.0 m Z 2 m X 2.0 c Quarks with a large PDF delay the + g gx u d s σ nx cm 2 20 GeV m Z universal m X GeV 20

21 Take aways Dark matter doesn t have a monopoly on monojets. The LHC will be the arbiter of multiple anomalies: solar neutrinos & DAMA/CoGeNT. The Tevatron reigns supreme at low masses. The mediator of DAMA/CoGeNT interactions is kinematically accessible at the LHC. Monojets are already uite constraining and may lead to the discovery of DM and/or non-standard neutrino interactions. 21