Semi-inclusive wino and higgsino annihilation to LL′
HJE
Semi-inclusive wino and higgsino annihilation to LL0
Matthew Baumgart 0 1 2 3
Varun Vaidya 0 1 3
0 Piscataway , NJ 08854 , U.S.A
1 Pittsburgh , PA 15213 , U.S.A
2 New High Energy Theory Center, Rutgers University
3 Department of Physics, Carnegie Mellon University
4 X. The radiative corrections
We systematically compute the annihilation rate for winos and higgsinos into the nal state relevant for indirect detection experiments, to this process receive enhancement from the large Bloch-Nordsieck-Violating Sudakov logarithm, log(2M =MW ). We resum the double logs and include single logs to xed order using a formalism that combines nonrelativistic and soft-collinear e ective eld theories. For the wino case, we update an earlier exclusion adapting results of the HESS experiment. At the thermal relic mass of 3 TeV, LL0 corrections result in a relative to LL. Nonetheless, single logs do not save the wino, and it is still excluded by an order of magnitude. Experimental cuts produce an endpoint region which, our results show, signi cantly e ects the higgsino rate at its thermal-relic mass near 1 TeV and is deserving of further study.
NLO Computations; Supersymmetry Phenomenology
-
2
eld theory of heavy WIMP annihilation
1 Introduction
3
4
2.1
2.2
2.3
3.1
3.2
Higgsino
Wino operators
Wino anomalous dimensions
Resummed wino annihilation rate
Anomalous dimensions
Resummed higgsino annihilation rate
Dark matter constraints and conclusion
A Neutralino masses and mixing
B Sommerfeld enhancement
B.1
Wino
B.2 Higgsino
C Photon wavefunction renormalization
the correct relic abundance has been dubbed the \WIMP Miracle" (cf. [
1
]). Since the
dynamics that set the electroweak scale are presently unknown, it is natural to go a step
further and propose that WIMP (Weakly-Interacting Massive Particle) dark matter arises
from the sector that solves the hierarchy problem. Supersymmetry (SUSY) is the classic
example of this `two-birds with one stone' approach to beyond the Standard Model physics.
However, the absence of superpartner discovery at the LHC and elsewhere has brought the
public perception of the theory into some disrepute. One may counter though, that this
very notion of SUSY's having a successful, simple DM candidate predicts precisely the
current experimental situation. The dark matter is necessarily the lightest supersymmetric
relic, this xes their masses to be Mwino
(M ) = 2.7-2.9 TeV or Mhiggsino
(M ) =
1 TeV [2{4]. Thus, the simple SUSY dark matter story has an electroweak LSP at or above
1 TeV, and thus has no observable collider signature for the foreseeable future.
While TeV-scale, weakly-interacting states are out of range of the current generation
of colliders, they represent a big target of opportunity for indirect detection experiments.
Observation of a nearly monochromatic line of photons at these energies would be a
smoking gun of new physics. The possibility of such experiments to set stringent limits on the
wino scenario was explored in [2, 5]. By combining a numerical calculation of the
Sommerfeld enhancement with a tree-level annihilation of WIMPs to
that the HESS experiment ruled out the wino by a factor of 15 under the assumption of
an NFW dark matter halo pro le [6]. In particular though, [5] extended their annihilation
calculation to one-loop and found a reduction in rate by
4
at the thermal relic mass of
3 TeV. In order to test such a large radiative correction, in our previous papers ([7, 8]), we
developed an e ective eld theory (EFT) approach to resum the large Sudakov double-logs
that appear, log(2M =MW ), factorizing their contribution from the Sommerfeld factors.
Although the gauge bosons in the theory are electroweak, the approach is based on two
di erent EFTs developed for QCD, non-relativistic QCD (NRQCD) [9] and soft-collinear
e ective theory (SCET) [10{13]. Since the experiment only detects one of the hard photons
from annihilation and its resolution is on the order of a few hundred GeV, we computed
the semi-inclusive annihilation rate, 0 0
!
+ X. We found the overall correction from
resummed double logs to be modest, with a few percent reduction in the cross section at
the relic density mass of 3 TeV relative to tree level (+ Sommerfeld enhancement). Thus,
the factor of
15 exclusion by HESS remained, unless one invoked a pro le with coring
& 1:5 kpc, in tension with recent simulations [14{16].
In between the release of our two papers, two other groups produced calculations using
e ective eld theory for wino annihilation [17, 18] to
a much larger reduction, getting roughly half the rate found at tree level. This need not
be a contradiction as our semi-inclusive cross section necessarily includes more processes.
Nonetheless, to improve our earlier, leading log (LL) resummed result, we now compute
the single-log contributions.
Despite being formally subleading in the power counting
parameter, working at single-log order brings in new e ects which have the poten (...truncated)