Hidden Sector particles at SNS

Transcription

1 Hidden Sector particles at SNS 1 S E N S I T I V I T Y T O A X I O N S A N D A X I O N - L I K E P A R T I C L E S. A T H A N S H A T Z I K O U T E L I S Y U R I E F R E M E N K O U N I V E R S I T Y O F T E N N E S S E E K N O X V I L L E

2 Outline 2 Introduction to Hidden sector particles. Sensitivity calculations. Discussion and future plans. References (unless stated): The report of the HSPAW workgroup at the Intensity Frontier: terature/darkphoton/intensityfrontier11.pdf

3 WISPS 3 Weakly interacting sub-ev (or slim") particles. Generic name for all these. Axions & ALPs. Born from the Strong CP problem. Magnetic photon / pseudo-scalar quantum numbers. Dark matter candidates. Hidden Sector Photons. new forces by non abelian U(1) gauge bosons also called U-bosons, or hidden-sector, heavy, dark, para-, and secluded photons couple very weakly to electrically charged particles Mili-charged particles (or mini-). Small un-quantized charged. Extra dimension scenarios. Dark matter candidates. Chameleons. May be the field that generates the dark energy. Mass depends on matter density. May hide energy from gravity.

4 Parameter space for hidden photons 4 M A <1 MeV M A > 1 MeV

5 Light particle Future Searches Helioscopes Primakoff effect. Thermal photons interacting with solar nuclei. Signal: excess of X-rays during alignment over background. 5 Resonantly-enhanced Photon Regeneration Light shining through wall Laser and X-ray optics techniques. For further reading:

6 Heavy Dark-Sector particles 6 Colliding e + e - Proton Colliders e + e - γ+a γ+ l + + l - A : hidden sector particle. L, X : SM leptons. Coupling upper limit: 10-5 (BELLE, BaBar, BES-III,KLOE, CLEO) Example by BaBar : issue-of-symmetry-available/ New heavy particles Prompt decays into dark sector X DS (lepton jets). (CMS, ATLAS, CDF & D0)

7 Fixed-Target Experimental Searches Electron or Proton collisions. Decays to multiple channels di-lepton, pions, International interest of proposed dedicated experiments: Jefferson Lab (Hall A, Hall B/CLAS), SLAC, MAMI (Mainz), ELSA (Bonn), XFEL (DESY), COMPASS (CERN), 7

8 Beam principle NUMI beam design 8 Simplified principle

9 SNS beam dump Proton accelerator 1 GeV Hg material. Thickness >30cm. Parameters: Proton energy. Particle mass. Particle life-time. Distance of the detector. Only really free parameter. 9 Sensitivity calculations Assume particle total energy is the total proton energy: 1GeV It will give an upper limit in sensitivity. Assume mass & lifetime Defines particle speed & decay path from interaction point. Plot the other parameters vs. decay path. Decay Path Scan. Positioning the detector at various distances we can scan ranges of masses and couplings ( a function of lifetime).

10 distance from beam dump (m) Limits of Sensitivity 10 1.E+05 1.E+04 1.E+03 Practical distances 100m- 1km ALP, WISP decay paths at the SNS 1 MeV 10 MeV 100 MeV 1.E+02 1.E+01 1.E+00 1.E-01 1.E-02 1.E-03 1.E-04 1.E-15 1.E-14 1.E-13 1.E-12 1.E-11 1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 decay time of the ALP (sec) The simple tread lines represent the speed of the particle exiting the beam-dump. They average m/s.

11 Discussion Lifetime instead of coupling. Natural parameter of the particle (non-model depended). The coupling that the relevant literature uses is always associate to a ( or few) models accepted by the various authors. The original Axion at any of its possible values (models) cannot be seen at the SNS. F.de Boer et.al. hep-ph/ (Nov 2005) The limits of sensitivity are applied on the physical parameters of the experiment. The closest that a detector could go to a beam-dump may be 100m. See NUMI beam pic. The flux drops by R 3 so 1km from the dump is a good far limit. There is a lot of low mass (m< 100MeV) searches that exclude lifetimes down to 10-9 sec. There are no phenomenological or astrophysical constraints that restrict the mass. Same for the lifetimes of these heavy dark sector particles. 11

12 Detector discussion Experimental strategy: Economy reasoning favors multi-purpose experiments. Small : in particle physics scales (and costs). Making a detector mobile can scan various ranges of mass. It improves sensitivity ( for each mass, scans lifetime ranges instead of a value). Can be included in smaller grants, built by smaller collaborations. Beam-dump: rarely prime area for experiments Can share source (dump) with other experimental efforts/ideas. Detector design: Tracker /calorimeter combination. Popular around neutrino experiments, proven technique. Good vertex and mass reconstruction can scan decay vertices closer to the interaction point. Slower /heavier particles. Increase the scanned phase space. Signature: Di-particle with vertex in the beam-line. Electron, muon, or pion pairs depending on the mass. Mass reconstruction provides the particle mass. protons Signals excess gives the coupling strength to the pair. Life time and mass are measured independently from each other. Overall measurement is also model independent. Beam dump Beam dump. shielding 100m detector 12 electronics Front view Sampling Calorimeter ~10-12 Xo tracker 1km

13 Conclusion and Outlook The new territory of hidden sectors in particle physics motivates the community to investigate, weakly coupled particles. For such searches well tested designs can be used economically adding to the investigation a large parameter space of mass-lifetime for some of the heavy particles. Detailed simulations of the products and energies out of the SNS beam-dump are warranted. Does something like that exist already? What are the most prominent mass-life combos that can have the intermediate (<1GeV) energies and can decay within 100m-1km? Extensive literature search for models that predict hidden or dark states with similar masses/energies. E.g nucleon-nucleon Bremsstrahlung (NN NN+A ) in the sun, T=30MeV How it would scale in hot Hg? 13