a new dark photon search p-division seminar los alamos national laboratory roy j. holt physics...

A new dark photon search P-Division Seminar Los Alamos National Laboratory

Roy J. HoltPhysics DivisionArgonne National Lab

26 February 2015

What’s the matter?

Argonne National Laboratory

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Dark matter is:

•a most profound mystery of modern physics

•a central element of cosmology and astronomy

•most of the mass of the Universe


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Intensity Frontier Workshop, Dec 2011, www.intensityfrontier.orgConvenors for nuclear physics: Haxton, Lu, Ramsey-Musolf

Priorities according to Nima Arkani-Hamed,Institute for Advanced Study (Princeton)

Dark Matters

Dark matter exists and interacts by gravity– Rotation curves of galaxies, gravitational lensing– Cluster galaxies– …

Is there a Standard Model connection to the dark sector?– Does dark matter interact in any other way than by gravity?

Dark photons might provide a “portal” to the dark sector U(1) extensions of the Standard Model are natural

– Pseudoscalar U(1) axions (strong CP problem)– Vector U(1) dark photons


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Rotation curves of galaxies


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F. Zwicky, ApJ 86 (1937) 217, V. Rubin et al, ApJ 238 (1980) 471Figure credit: H. Merkel

Dark photons explain mass extinctions?


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FIG. 2: Our Solar System orbits around the Milky Way’s center, completing a revolution every 250 million years.Along this path, it oscillates up and down, crossing the galactic plane about every 32 million years. If a dark matter diskwere concentrated along the galactic plane, as shown here, it might tidally disrupt the motion of comets in the Oort cloudat the outer edge of our Solar System. This could explain possible periodic fluctuations in the rate of impacts on Earth.(APS/Alan Stonebraker)L. Randall and M. Reece, PRL 112 (2014) 161301; J. I. Read et al, Mon. Not. Roy. Astro. Soc 389 (2008) 1041

Very active field with many new results


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Positron observations from satellite data


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M. Aguilar et al., PRL 113 (2014) 121101

Positron excess from AMS-02


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typical theory Expectation

Pulsars?

M. Aguilar et al., PRL 113 (2014) 121101

Positron excess decreases at high energy


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Consistent with ~ 1 TeV dark matter particles annihilating?

S. Ting, CERN press release forAMS collaboration, Sept. 18, 2014

No anti-proton excess


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O. Adriani et al., Nature 458 (2009) 607

Gamma-ray excess from the Galactic Center


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P. Agrawal et al., arXiv: 1404.1373T. Daylan et al, arXiv: 1402.6703Hooper and Linden, PRD, arXiv:1110.0006

B. D. Fields, S. L. Shapiro, J. Shelton,PRL 113 (2014) 151302

The Economist, April 12, 2014

• Not yet explained by known astrophysical sources

• Can be explained by dark matter annihilation

• What about a black hole spike?

Sagittarius A*Supermassive blackhole at GC

Dark matter search strategies


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SM

SM

Direct production:LHC

Direct search:CDMS, DAMA, XENON, CREST, LUXCOUPP, PICO, MiniCLEAN, …

Indirect search:PAMELA, Fermi, HESS, ATIC, AMS-02, WMAP

New Force ?


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Standard Model

Quarks, leptons

g W Z

Standard Model

Quarks, leptons

g W Z

Hidden Sector

dark matter

A’

Hidden Sector

dark matter

A’

Known forces Dark force?

SU(3)C x SU(2)W x U(1)Y U(1)’

Strong weak EM

Dark photons might provide a portal to dark matter


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Standard Model

Quarks, leptons

g W Z

Standard Model

Quarks, leptons

g W Z

Hidden Sector

dark matter

A’

Hidden Sector

dark matter

A’

B. Holdom, PLB 166 (1986) 196J. D. Bjorken et al, PRD 80 (2009) 075018

~ 1E-2 to 1E-8 from loops of heavy particles

•Discovery of dark photons would be revolutionary•Dark photons could explain:

• positron excess in high energy Cosmic rays• Gamma ray excess near Galactic Center• (g-2) of the muon anomaly• …

Muon (g-2)


16H. Davoudias et al, PRD 89 (2014) 095006

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Dark Photons at RHIC ?Muon g-2 experiment (E821) has 3.6 result beyond the Standard Model

PHENIX has excellent dark photon search capabilities

No dark photon signal seen

PHENIX upper limit, plus othersrules out dark photons withno hidden sector decays as g-2 explanation

A. Adare et al, arXiv:1409.0851

The search is on …


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Courtesy: R. Milner at the Fundamental Interactions Town Meeting, Chicago, Sept. 28-29, 2014

XA’

(also ALICE)

Possible production mechanisms for dark photons

Bremsstrahlung

0, , … decay

Drell-Yan (J.-C. Peng, S. Prasad)


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A’

p

pl+

l-

Dark forces: decay


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Courtesy: N. Toro

~ 1E-2 to 1E-8 from loops of heavy particles

Most of the relevant parameter space is not shown


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Plot: W. Marciano

Non-Standard Model Higgs decays at the LHC


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arXiv: 1409.0746

Hidden Lightest Stable ParticleHidden

fermion

Hiddenscalar

BR(H -> 2d) = 5 -40% ??

Main injector at FNAL - 120 GeV protons


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Fermilab E906/SeaQuest CollaborationAbilene Christian University

Ryan Castillo, Michael Daugherity, Donald Isenhower, Noah Kitts, Lacey Medlock, Noah Shutty, Rusty Towell, Shon Watson,

Ziao Jai Xi

Academia SinicaWen-Chen Chang, Ting-Hua Chang, Shiu Shiuan-Hao

Argonne National LaboratoryJohn Arrington, Don Geesaman*, Kawtar Hafidi,

Roy Holt, Harold Jackson, David Potterveld, Paul E. Reimer*, Brian Tice

University of ColoradoEd Kinney, Joseph Katich, Po-Ju Lin

Fermi National Accelerator LaboratoryChuck Brown, Dave Christian, Su-Yin Wang, Jin-Yuan Wu

University of IllinoisBryan Dannowitz, Markus Diefenthaler, Bryan Kerns, Hao Li, Naomi C.R Makins, Dhyaanesh Mullagur R. Evan McClellan,

Jen-Chieh Peng, Shivangi Prasad, Mae Hwee Teo, Mariusz Witek, Yangqiu Yin

KEKShin'ya Sawada

Los Alamos National LaboratoryGerry Garvey, Xiaodong Jiang, Andreas Klein, David Kleinjan,

Mike Leitch, Kun Liu, Ming Liu, Pat McGaughey

Mississippi State UniversityLamiaa El Fassi

University of MarylandBetsy Beise, Yen-Chu Chen, Kazutaka Nakahara

University of MichiganChristine Aidala, McKenzie Barber, Catherine Culkin, Vera

Loggins, Wolfgang Lorenzon, Bryan Ramson, Richard Raymond, Josh Rubin, Matt Wood

National Kaohsiung Normal UniversityRurngsheng Guo, Su-Yin Wang

RIKENYoshinori Fukao, Yuji Goto, Atsushi Taketani, Manabu Togawa

Rutgers, The State University of New JerseyRon Gilman, Ron Ransome, Arun Tadepalli

Tokyo TechShou Miyaska, Kei Nagai, Kenichi Nakano, Shigeki Obata,

Florian Sanftl, Toshi-Aki Shibata

Yamagata UniversityYuya Kudo, Yoshiyuki Miyachi, Shumpei Nara

*Co-Spokespersons

5 national labs, 11 universities!

Drell-Yan measurements on the proton and deuteron


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ubar > dbar

J.-C. Peng et al, PLB 736 (2014) 411

Revealing the “Peng effect”

Ideal beam stop experiment


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Detector is well-shielded from Standard Model background

Vertex for pair production is downstream from the target

mA’ = invariant mass of

Resonance production

target shield pair spectrometer

High energy

Proton beam

A’

l+

l-

SeaQuest Experiment


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Lint(Fe) = 0.17 m = target lengthShield (Fe) = 4.8 m – <Lint> Fiducial region = LFe + 0.95 m

Figure credit: Kenichi Nakano, Shou Miyasaka

Solid Fe magnet – thanks to DOE for fundingand for lack of funding

1-m Fe

Branching ratios for A’ decay assuming no hidden sector decays


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D. Curtin, et al, arXiv 1312.4992v2R. Essig, priv. comm. (2014)

SeaQuest Experimental Setup


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•Spectrometer commissioned in March 2014•Experiment will run for at least another year

followed by LANL’s E1039 experiment•Nearly ideal for a dark photon search

LANL LDRD -> more ideal

Thanks to R. Evan McClellan

Preliminary

Decay length vs. mass, energy,


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J. D. Bjorken et al, PRD 80 (2009) 075018

Charged particle production at 120 GeV


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S. Mahajan, R. Raja, arXiv:1311.2258; FNAL E907, MIPP

= 2.2 b for all charged particle productionAssume that ’s represent 90% of charged particles,

and production is 1/10 of this value.

Resonance production

Proton bremsstrahlung


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p

p’l+

l- + p -> ’+ p’

Generalized Fermi-Williams-Weizsacker approximation

J. Blumlein, J.Brunner, PLB 731 (2014) 320

z = (Ep – Ep’)/Ep; s = 2MEp; s’ = 2M(Ep – EA’)

Proton bremsstralung flux


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= 1

Worldwide search for dark photons (exclusion plot)


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JLab projections

FNAL E906SeaQuestprojectionspreliminary

Plot credit: A. Tadepalli

2E12 ppp100% efficiency200 days10 event contours

How would 50 events with S/B = 1:1 appear?


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SeaQuest Projections preliminary

With e+e- detection

Dark Matter can come in different shades of gray?


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Slide credit: S. Gardner

The visible and hidden sectors can mix in different ways…

[Note Batell, Pospelov, and Ritz, PRD 80 (2009) 095024 for a review re fixed target expts.]Here we consider a non-Abelian (gluon) portal [Baumgart et al., JHEP 0904, 014 (2009); Gardner and He, PRD 87 (2013) 116012]The “shining through walls” design – unique to Seaquest – makes this possible , to yield, e.g., via a “minimal” decay….

With detection

SeaQuest Projections preliminary

Production [

First look at background events


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Monte Carlo: p - inelastic scattering Actual data - 8 hours

Fiducial region

Fiducial region

Thanks to Kun Liu09 May 2014Tracker is not yet optimized for dark photonsTrigger 57, not optimal for dark photons

Second look for possible events


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Runs 8919-9117 ~90 hours,

Very preliminary

Thanks to R. Evan McClellan20 October 2014Same tracker as beforeTrigger 59

Distance (cm)

Distance (cm)

Summary

Existence of dark matter is a reason to investigate new forces New initiative for SeaQuest - search for dark photons Leverage the newly commissioned spectrometer and 120 GeV

proton beam at FNAL Ultimate goal is to discover dark photons and provide a window

into dark matter in a laboratory setting Detecting e+e- and in SeaQuest would greatly extend the

reach, possibly including some non-Abelian dark forces Next few years: a discovery or a large excluded region of

parameter space Don’t be afraid of the dark!


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Extra slides


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Confidence levels

CLs or Becker method P(n,x) is the Poisson probability to observe n events for a mean value of x N = number of event observed, b = background events, s = signal

N=1, b=0.7, 95% CL exclude signal of 4.5 events, proton bremsstrahlungJ. Blumlein, J.Brunner, PLB 731 (2014) 320

N=5, b=3.5, 95% CL exclude a signal of 7.3 events, 0 decayJ. Blumlein, J.Brunner, PLB 701 (2011) 155


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Mass distribution for events 3-5 m downstream


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Thanks to R. Evan McClellan

Mass (GeV)

Even

tsVery preliminary

More assumptions

Beam intensity – 6 x 1012 protons per minute Beam protons rejected - 40% Dark photon acceptance – 50% Dead time - 15% Target thickness – 1 interaction length of Fe Dimuon tracking efficiency – 50% Time – nominal year - 200 days Minimum number of dark photon events – 10 Signal to background – 1:1 Confidence level - 95%


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Drell-Yan is the best way to measure sea-quark distributions


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What is the A dependence of antiquarks?

Longer term: Polarized FNAL/target, J-PARC

Commissioning completedMarch 2014

a new dark photon search p-division seminar los alamos national laboratory roy j. holt physics...

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