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Re s u m me d P h o t o n s p e c t r u m f r o m WI M P a ...
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Resummed Photon spectrum from WIMP annihilation Varun Vaidya Theoretical division, LANL In collaboration with : M Baumgart, T Cohen, I. Moult, N. Rodd, T. Slatyer, M. Solon. I .Stewart
Transcript of Re s u m me d P h o t o n s p e c t r u m f r o m WI M P a ...
Resummed Photon spectrum from
WIMP annihilation
Varun Vaidya
Theoretical division, LANL
In collaboration with :M Baumgart, T Cohen, I. Moult, N. Rodd, T. Slatyer, M. Solon. I .Stewart
Outlinen History
n Geography
n Economics
l Wino Dark Matterl Indirect dectection of Dark Matter l Previous results and need for a new calculation
l Kinematics l Set up of EFTl Resummation
l Differential photon spectra l Updated exclusion for the Wino
History
l SUL(L) triplet fermion χ, superpartner of weak gauge bosons, free mass parameter M2 ~ TeV
l Mass eigenstates after electroweak breaking:
Neutralino : Majorana fermion
Chargino
l Mass splitting of 170 MeV from electroweak radiative corrections
l Neutral state χ0 is the LSP -> Dark matter WINO
Wino Dark Matter
Wino annihilation to photons
l Semi- inclusive cross section of annihilation to a hard photon .
l The wino's are non relativistic , v ~ 10-3
l Interaction has two contributions :
l Phase 1 : Well separated slow moving fermions interact via gauge boson exchange
χ0
χ0
χ0
χ0
or
χ+
χ-
each rung ~ αwMχ/Mw
Sommerfeld enhancement
l Effect captured by solving Schrodinger equation with effective potential
n Sommerfeld enhancement for two channels
, ψ = ψ+-
ψ00
ψ+-
ψ00
Hard scattering to photon
χ0
χ0
γ
γ,Z
χ+
χ-
γ
γ, Z
χ+ χ- W+
γχ0
χ0
W+
χ-
W-
χ+
χ- γ
W+
W-
Exclusive cross section
Continuum cross section
What does the spectrum look like?
What does the spectrum look like?
l KLN* : An IR safe observable needs to be suffciently inclusive over its final states.
l These apear as Sudakov double logs αw ln2(Mχ/MW)
l Also contains αw ln2(1-z) from incomplete phase space cancellations
*Kinoshita–Lee–Nauenberg theorem
Assume there is no EW breaking A W3 is indistinguishable from a W1-W2 pair created from its collinear splitting
Previous results
l Wino under siege :
T. Cohen, M. Lisanti, A. Pierce and T. R. Slatyer, JCAP { 1310}, 061 (2013)
l Exclusive cross section at NLL G. Ovanesyan, T. R. Slatyer and I. W. Stewart, Phys. Rev. Lett. 114, no. 21, 211302 (2015)
l Semi-inclusive annihilation
M. Baumgart, I. Z. Rothstein and V. Vaidya, JHEP 1504, 106 (2015)
Indirect Dark Matter Detection
l Detection of high energy gamma rays from annihilation of cold Dark Matter particles
l Air Cherenkov Telescope : HESS - High energy stereoscopic system , Namibia
l HAWC: High altitude water Cherenkov
Observatory, Mexico
What does HESS see?Number of photons per unit volume of dark matter annihilation per unit time
Flux of photons from the direction of the galactic center
J Factor
l The telescope has a finite energy resolution which ranges from 11- 20% of the DM mass over the range 1-20 TeV
HESS Constraintsl HESS assumes a line spectrum while setting constraints and ignores the continuum inspite of having a finite resolution.
l Set limits on at a given DM mass
l Two changes are needed
ü Include continuum contribution near z = 1 while setting limits ü A theory calculation that gives accurate spectrum at and near z=1.
Geography
Factorizationl Kinematics: Light-cone co-ordinates
SCET (Soft Collinear effective theory) I
Factorized cross section
DM Wavefunction
Recoil jet function
Photon jet function
U-soft function
Ultrasoft Wilson line
Refactorizing the U-Soft functionThe U-Soft function S depends on two scales : Mx(1-z), Mw.Hence further factorization is needed to separate these scales.
Factorization
Hyperbolas of invariant masses in k+- k- plane
Anomalous dimensions
l 2Mx(1-z) ~ 1/s
Resummation at LL
Resummation path in the μ-ν plane
Resummed cross-section
Sommerfeld factors
Plus functions
Ressummed cross section
l We can identify three distinct logarithms :
Sudakov double logs from virtual corrections
Plus function with a threshold
Plus function with a threshold
Economics
Differential Spectra
Transition to inclusive and exclusive cases
l Exclusive limit
l Inclusive limit
G. Ovanyesan, T. Slatyer, I. Stewart
M. Baumgart, I. Rothstein, V. Vaidya
Modified constraints l HESS line flux
l HESS true flux
Set limits on line + continuum or
strenghten limits on the line( exlusive) cross section
Exclusion plot for WINO
Limits on J factor
Summary and Outlook
l Most accurate calculation of resummed WIMP photon spectrum
l Supercedes all earlier calculations
l Demonstrates the need to include continuum contribution in photon flux for DM data analysis
l Updated constraints on Heavy DM
l EFT developed can be easily used for other heavy DM models as well as for general collider physics
l Apply these techniques for the Higgsino
l Collaborate with existing and upcoming experiments for refining constraints
