Coherent scattering of light objects on nuclei. Maxim Pospelov Perimeter Institute/U of Victoria

Transcription

1 Coherent scattering of light objects on nuclei Maxim Pospelov Perimeter Institute/U of Victoria Cui, Pospelov, Pradler, 207, PRD Bringmann, Pospelov, 208, subm to PRL Earlier papers with Deniverville, Batell, Ritz

2 Plan. Introduction. We invest in neutrino and direct detection experiments (including CEvNS) which are sensitive to variety of New Physics models 2. Example : energetic dark radiation, neutrino or otherwise 3. Example 2: light dark matter accelerated to large velocities 4. Conclusions 2

3 Cosmological surprises Existence of dark matter and dark energy calls into question whether there are other dark components: Dark Forces? Dark radiation? 3

4 Dark Radiation? Dark radiation existed in the form of neutrinos. At the time of the matter-radiation equality, about 40% of radiation energy density was encapsulated by neutrinos, and is fully captured by both BBN and CMB. New radiation like degrees of freedom (p DR = /3 r DR ) are limited by N eff. SM predicts Current limit is / Strong constraint on fully thermalized species. New DR? If not interacting with the SM only through N eff. However, if there is interaction, we have additional ways of probing DR.

5 Two cases for Dark Radiation Case : numerous soft quanta (interesting for EDGES)! DR! CMB, n DR >n RJ,! DR n DR tot. Case 2: fewer hard quanta amenable for detection with DD experiment n DR n, E DR E, DR ( E DR n DR ) apple 0. DM

6 Decay of DM to dark radiation Scenario: A fraction of DM decays, producing fluxes of relativistic particles. DM à DR + DR, followed by DR + nucleus à recoil Daughter particles can be anything: neutrinos and/or other light dark states. The parameter space of such models is rather complicated: {mass DM, mass DR, t DM, DR interaction strength} Region of DM mass of interest for this talk MeV to GeV

7 Attainable fluxes of DR. Scenario: A fraction of DM decays, producing fluxes of relativistic particles. DM à DR + DR 6 Typical spectra has a galactic and extra-galactic component: 04 galactic (5% smearing) X = 0 Gyr 0 Gyr, mx = 50 MeV and = 0.. max = 50 MeV = 0. width has been applied to the galactic or X = an of 5% display. total flux tot, integrated over the whole energy m, varies over many orders of magnitude dependthe choice parameters. Nevertheless, one can estihe maximum 03 possible flux at 0., X = 0 Gyr, aking m! 0, and keeping mx as0a free parame (MeV) = 0. m = 5 MeV 3 extragalactic (m = 0) extragalactic (m = 5 MeV) X /t0 d /de (/MeV/cm2 /sec) gal e.g. total (cm2 /s) (cm2 /s) 00 mx (MeV) 000 Fig. for X Gaussian of 5 flux for displa The total fl spectrum, var ing on the ch mate the max while taking eter: Completely c become com mx 0 Me many orders demonstrates times and X Could be comparable to solar neutrino fluxes, but more energetic creating DD sign. 0 MeVand extragalactic FIG. di erential particle fluxes max. Galactic 6 0 cm 2decay s. X! (23) tot monochromatic from 2-body 2. The solid mx (dashed) line is for a massless (5 MeV) daughter particle. FIG. 2. Integral galactic ( gal. ) and extragalactic ( e.g. ) particle fluxes from monochromatic 2-body decay X! 2. The labeled contours are in units of /cm2 /s. A mass of m = 5 MeV has been assumed. 4. SC A.

8 Decay to SM neutrinos {mass DM, mass DR, t DM, DR interaction strength} A new population of SM neutrinos could be created by the DM decay. Constraints on electron antineutrinos by SK are very strong, but for neutrinos with E < 30 MeV the constraints are not that strong, and direct detection will soon become competitive DR = SM SK(dsnb) X/t SK(sol) SK(atm) XENONT LUX m X (MeV) With such exotic n DR, the neutrino floor is closer, at 0-47 cm 2.

9 Let us classify possible connections between Dark sector and SM H + H (l S 2 + A S) Higgs-singlet scalar interactions (scalar portal) B µn V µn Kinetic mixing with additional U() group (becomes a specific example of J µi A µ extension) LH N neutrino Yukawa coupling, N RH neutrino J µi A µ requires gauge invariance and anomaly cancellation It is very likely that the observed neutrino masses indicate that Nature may have used the LHN portal Dim>4 J µ A µ a /f. Neutral portals to the SM axionic portal 9

10 Decay to DR coupled to baryons A new population of fermions that interact with baryonic current could be created by the DM decay. Constraints from SK are not strong, and direct detection is the most sensitive probe: 0. Rate in Xe with ER > kev (kg 04 0 day ). DR = X /t0 X /t0 the each atm) e SN rent GB = 0GF m = 0 MeV form of flux of s given in tains sa paring through imum va have a c 0 Borexino gal. e.g. sum = 0. m =0 00 progenitor mass mx (MeV) 000 FIG. 5. Predicted recoil rate R(ER > kev) for DR consisting of massless particles that are coupled to the baryon current with strength GB = 0GF, in units of events/kg/day, and for xenon as detector material XENONT LUX 00 mx (MeV) 000 FIG. 6. Constraints on DR coupled to SM, at 95% C.L., through gauged baryon number with GB = 0GF from the direct detection experiments LUX and XENONT as well as from the neutrino experiment Borexino. Two cases are shown: the solid line is for m = 0 and dotted line is for m = Direct detection rates put significant constraints on models. Need more than species do differentiate between DR and DM recoil. Curre in the m techniqu (For som of DR do of the co It is e the benc outside ALP de searches as IAXO for ALP The exp

11 Second topic: light DM A limited number of concrete testable models of DM can be constructed in the sub-gev range. (Battaglieri et al, 207) On can look for it in the neutrino and beam dump experiments (Batell et al, 2009) Coherent neutrino scattering is a [future] way of constraining light dark matter created in beam dump (cross section is enhanced) There is also some merit in a less model-dependent approach, when you just look for DM within a simplified parameter space: {m c,s c }

12 MiniBooNE search for light DM arxiv: , PRL 207 Target Decay Pipe Beam Dump MiniBooNE Detector p Be Air 0 V Steel Earth N 50 m 4m 487 m ) 4 Events/(e20 POT) NCE Off Data (stat errors) Total Bkg (sys errors) Beam unrel. bkg ν det ν dirt Q (GeV ) QE I No nuisance parameters applied yet #events uncertainty BUB 697 det bkg 775 dirt bkg 07 Total Bkg % (pred. sys.) Data % (stat.) 2 0 m Subject to future improvement with much closer new detector at SNB χ V /m χ Y = ε 2 α'(m µ g-2 favored + + K π +invis. LSND E37 Preliminary Relic Density = 3m χ, α' = 0.5 m V MiniBooNE 90% CL J/ψ invis. BaBar MiniBooNE 90% Sensitivity Direct Det. 0 (GeV) 2

13 J/ψ invis. K+ π++invis. 0 7 Monojet (CDF) Neutron Scattering 0 4 Recent results and new proposals 0 8 BaBar MB Elastic N 9 0 Direct Detection Nucleon MB Full N + Timing 0 6 MB Electron + Timing Direct Detection Nucleon αb (mv = 3mχ) Y = ε2αd(mχ/mv)4 (mv = 3mχ, αd = 0.5) MB Elastic N 0 5 αµ favored 0 7 Z γ +invis. Example from this year: MiniBoNE result of light DM search ( ): XENON0/00 χ-e E K π+invis. 0 0 NA64 0 Relic Density 0 Very expensive and versatile experiments in particle physics have already been built, or will be built (LHC, Belle-II, DUNE, Hyper-K) LSND mχ (GeV/c2) mχ (GeV/c2) (a) vector portal (b) leptophobic FIG. 25. Comparing MiniBooNE confidence level limits (solid lines), and sensitivities (dashed lines) to other experiments for (a) Y as a function of m assuming D = 0.5 and mv = 3m and (b) in the leptophobic dark matter model with mv = 3m. Explanation of vector portal limits lines are given in Refs. [9, 25, 29 3]. Explanation of the leptophobic limit lines are given in Refs. [8, 27, 28]. Dark sector research will be important direction for many. MB Elastic N BaBar 9 0 MB Electron + Timing XENON0/00 χ-e- 0 0 E37 Relic Density 0 NA Direct Detection Nucleon MB Elastic N MB Full N + Timing MB Electron + Timing 0 NA64 E SH ip / 0 0 MMAPS 0-0 CRESST II SBNπ E37 0- NA64 Belle II LSND one ibo Min BaBar BD X O N 0-8 BaBar XENON0/00 χ-e J/ψ Direct invis.detection Nucleon αµ favored X EN 0 y = ϵ2αd (m χ/ma')4 αµ favored Y = ε2αd(mχ/mv)4 (mv = 7mχ, αd = 0.5) Y = ε2αd(mχ/mv)4 (mv = 3mχ, αd = 0.) 9 COHE RENT Relic Density 0 8 MB Full N + Timing Scalar Elastic DM (Kinetic Mixing) K+ π++invis. K+ π++invis. get Tar elic R lar e SBN Sca MX LD 0-5 LSND 3 LSND mχ (GeV/c2) 0 (a) vector portal ( D = 0., mv = 3m ) mχ (GeV/c2) 0 (b) vector portal ( D = 0.5, mv = 7m ) m χ [MeV] FIG % confidence level in the vector portal dark matter model with (a) Y as a function of m assuming D = 0. and mv = 3m and (b) D = 0. and mv = 7m. Explanation of limits lines are given in Refs. [9, 25, 29 3] Future LDMX-type experiments will add larger capabilities 3

14 Light DM can be searched with coherent scattering on nuclei Assuming ton experiment, Deniverville, Pospelov, Ritz, 205 baryonic force dark photon force

15 Search for WIMP-nucleus scattering (latest LUX, XENON T and PANDA-X results) What about MeV mass range? Optimum sensitivity, m WIMP ~ m Nucleus (a little lighter because of nuclear form factor). No sensitivity below m WIMP ~ few GeV, due to exceedingly small recoil that does not give much light or scintillation. 5

16 Finally: light DM accelerated due to its interaction There is always a small energetic component to DM flux (Bringmann, Pospelov, 208). There is also some merit in a less model-dependent approach, when you just look for DM within a simplified parameter space: {m c,s c }. Typically: MeV DM mass à kev kinetic energy à sub-ev nuclear recoils. No limits for s nucleon-dm for DM in the MeV range. This is not quite true because there is always an energetic component for DM, not bound to the galaxy. Generated through the very same interaction cross section: s c Main idea: Collisions of DM with cosmic rays generate subdominant DM flux with ~ 00 MeV momentum perfect for direct detection type recoil. T χ dφ/dt χ [cm -2 s - ] SHM x f (v/c) σ χ = 0-30 cm T χ [GeV]

17 Resulting limits Spin-independent limits. [Notice the constraint from Miniboone, from measurements of NC nu-p scattering]. Exclusion of s = cm 2! Scattering on free protons in e.g. Borexino is also very constraining for the spin-dependent scattering.

18 Conclusions. Interacting DR can be searched for in direct detection [of DM] experiments. The maximum strength signal from DR neutrinos will be reached relatively soon. 2. Future ton experiments looking for measuring (!) CEvNS, can also be used for constraining very light DM created in beam dumps. 3. New limits are derived on {m c,s c } parameter space using subdominant energetic fraction of DM created by collisions with cosmic rays with subsequent scattering in DM and neutrino experiments. 8