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Author |
Gelmini, G.B.; Huh, J.H.; Witte, S.J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Unified halo-independent formalism from convex hulls for direct dark matter searches |
Type |
Journal Article |
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Year |
2017 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
12 |
Issue |
12 |
Pages |
039 - 33pp |
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Keywords |
dark matter experiments; dark matter theory |
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Abstract |
Using the Fenchel-Eggleston theorem for convex hulls (an extension of the Caratheodory theorem), we prove that any likelihood can be maximized by either a dark matter 1-speed distribution F(v) in Earth's frame or 2-Galactic velocity distribution f(gal) ((u) over right arrow), consisting of a sum of delta functions. The former case applies only to time-averaged rate measurements and the maximum number of delta functions is (N-1), where N is the total number of data entries. The second case applies to any harmonic expansion coefficient of the time-dependent rate and the maximum number of terms is N. Using time-averaged rates, the aforementioned form of F(v) results in a piecewise constant unmodulated halo function (eta) over tilde (BF)-B-0 (v(min)) (which is an integral of the speed distribution) with at most (N-1) downward steps. The authors had previously proven this result for likelihoods comprised of at least one extended likelihood, and found the best-fit halo function to be unique. This uniqueness, however, cannot be guaranteed in the more general analysis applied to arbitrary likelihoods. Thus we introduce a method for determining whether there exists a unique best-fit halo function, and provide a procedure for constructing either a pointwise con fi dence band, if the best-fit halo function is unique, or a degeneracy band, if it is not. Using measurements of modulation amplitudes, the aforementioned form of f(gal) ((u) over right arrow), which is a sum of Galactic streams, yields a periodic time-dependent halo function (eta) over right arrow BF (v(min); t) which at any fixed time is a piecewise constant function of v(min) with at most N downward steps. In this case, we explain how to construct pointwise confidence and degeneracy bands from the time-averaged halo function. Finally, we show that requiring an isotropic Galactic velocity distribution leads to a Galactic speed distribution F(u)that is once again a sum of delta functions, and produces a time-dependent (eta) over tilde BF (v(min); t) function (and a time-averaged (eta) over tilde (0) BF (v(min))) that is piecewise linear, di ff ering significantly from best-fit halo functions obtained without the assumption of isotropy. |
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Address |
[Gelmini, Graciela B.; Witte, Samuel J.] Univ Calif Los Angeles, Dept Phys & Astron, 475 Portola Plaza, Los Angeles, CA 90095 USA, Email: gelmini@physics.ucla.edu; |
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Publisher |
Iop Publishing Ltd |
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English |
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ISSN |
1475-7516 |
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Notes |
WOS:000418922000002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial ![sorted by Serial field, descending order (down)](img/sort_desc.gif) |
3440 |
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Permanent link to this record |
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Author |
Achterberg, A.; van Beekveld, M.; Caron, S.; Gomez-Vargas, G.A.; Hendriks, L.; Ruiz de Austri, R. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Implications of the Fermi-LAT Pass 8 Galactic Center excess on supersymmetric dark matter |
Type |
Journal Article |
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Year |
2017 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
12 |
Issue |
12 |
Pages |
040 - 23pp |
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Keywords |
dark matter theory; galaxy morphology; cosmology of theories beyond the SM; dwarfs galaxies |
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Abstract |
The Fermi Collaboration has recently updated their analysis of gamma rays from the center of the Galaxy. They reconfirm the presence of an unexplained emission feature which is most prominent in the region of 1-10 GeV, known as the Galactic Center GeV excess (GCE). Although the GCE is now fi rmly detected, an interpretation of this emission as a signal of self-annihilating dark matter (DM) particles is not unambiguously possible due to systematic effects in the gamma-ray modeling estimated in the Galactic Plane. In this paper we build a covariance matrix, collecting different systematic uncertainties investigated in the Fermi Collaboration's paper that affect the GCE spectrum. We show that models where part of the GCE is due to annihilating DM is still consistent with the new data. We also re-evaluate the parameter space regions of the minimal supersymmetric Standard Model (MSSM) that can contribute dominantly to the GCE via neutralino DM annihilation. All recent constraints from DM direct detection experiments such as PICO, LUX, PandaX and Xenon1T, limits on the annihilation cross section from dwarf spheroidal galaxies and the Large Hadron Collider limits are considered in this analysis. Due to a slight shift in the energy spectrum of the GC excess with respect to the previous Fermi analysis, and the recent limits from direct detection experiments, we find a slightly shifted parameter region of the MSSM, compared to our previous analysis, that is consistent with the GCE. Neutralinos with a mass between 85-220 GeV can describe the excess via annihilation into a pair of W-bosons or top quarks. Remarkably, there are models with low fine-tuning among the regions that we have found. The complete set of solutions will be probed by upcoming direct detection experiments and with dedicated searches in the upcoming data of the Large Hadron Collider. |
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Address |
[Achterberg, Abraham; van Beekveld, Melissa; Caron, Sascha; Hendriks, Luc] Radboud Univ Nijmegen, Fac Sci, Inst Math Astrophys & Particle Phys, Mailbox 79,POB 9010, NL-6500 GL Nijmegen, Netherlands, Email: a.achterberg@astro.ru.nl; |
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Publisher |
Iop Publishing Ltd |
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English |
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ISSN |
1475-7516 |
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Notes |
WOS:000418922000003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial ![sorted by Serial field, descending order (down)](img/sort_desc.gif) |
3439 |
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Permanent link to this record |
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Author |
Barenboim, G.; Park, W.I. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Lepton number asymmetries and the lower bound on the reheating temperature |
Type |
Journal Article |
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Year |
2017 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
12 |
Issue |
12 |
Pages |
037 - 13pp |
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Keywords |
cosmological neutrinos; physics of the early universe |
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Abstract |
We show that the reheating temperature of a matter-domination era in the early universe can be pushed down to the neutrino decoupling temperature at around 2 MeV if the reheating takes place through non-hadronic decays of the dominant matter and neutrino-antineutrino asymmetries are still large enough, vertical bar L vertical bar greater than or similar to O(10(-2)) (depending on the neutrino flavor) at the end of reheating. |
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Address |
[Barenboim, Gabriela] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain, Email: Gabriela.Barenboim@uv.es; |
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Publisher |
Iop Publishing Ltd |
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English |
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ISSN |
1475-7516 |
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Conference |
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Notes |
WOS:000418672700001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial ![sorted by Serial field, descending order (down)](img/sort_desc.gif) |
3430 |
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Permanent link to this record |
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Author |
Escudero, M.; Witte, S.J.; Hooper, D. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Hidden sector dark matter and the Galactic Center gamma-ray excess: a closer look |
Type |
Journal Article |
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Year |
2017 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
11 |
Issue |
11 |
Pages |
042 - 29pp |
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Keywords |
dark matter experiments; dark matter theory |
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Abstract |
Stringent constraints from direct detection experiments and the Large Hadron Collider motivate us to consider models in which the dark matter does not directly couple to the Standard Model, but that instead annihilates into hidden sector particles which ultimately decay through small couplings to the Standard Model. We calculate the gamma-ray emission generated within the context of several such hidden sector models, including those in which the hidden sector couples to the Standard Model through the vector portal (kinetic mixing with Standard Model hypercharge), through the Higgs portal (mixing with the Standard Model Higgs boson), or both. In each case, we identify broad regions of parameter space in which the observed spectrum and intensity of the Galactic Center gamma-ray excess can easily be accommodated, while providing an acceptable thermal relic abundance and remaining consistent with all current constraints. We also point out that cosmic-ray antiproton measurements could potentially discriminate some hidden sector models from more conventional dark matter scenarios. |
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Address |
[Escudero, Miguel; Witte, Samuel J.] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, Apartado Correos 22085, E-46071 Valencia, Spain, Email: miguel.escudero@ific.uv.es; |
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Thesis |
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Publisher |
Iop Publishing Ltd |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1475-7516 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000417561900005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial ![sorted by Serial field, descending order (down)](img/sort_desc.gif) |
3412 |
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Permanent link to this record |
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Author |
LUX-ZEPLIN Collaboration (Akerib, D.S. et al); Bailey, A.J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Identification of radiopure titanium for the LZ dark matter experiment and future rare event searches |
Type |
Journal Article |
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Year |
2017 |
Publication |
Astroparticle Physics |
Abbreviated Journal |
Astropart Phys. |
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Volume |
96 |
Issue |
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Pages |
1-10 |
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Keywords |
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Abstract |
The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a detector containing a total of 10 tonnes of liquid xenon within a double -vessel cryostat. The large mass and proximity of the cryostat to the active detector volume demand the use of material with extremely low intrinsic radioactivity. We report on the radioassay campaign conducted to identify suitable metals, the determination of factors limiting radiopure production, and the selection of titanium for construction of the LZ cryostat and other detector components. This titanium has been measured with activities of U-238(e) < 1.6 mBq/kg, U-238(I) < 0.09 mBq/kg, Th-232(e) = 0.28 +/- 0.03 mBq/kg, Th-232(I) = 0.25 +/- 0.02 mBq/kg, K-40 <0.54 mBq/kg, and (60) Co <0.02 mBq/kg (68% CL). Such low intrinsic activities, which are some of the lowest ever reported for titanium, enable its use for future dark matter and other rare event searches. Monte Carlo simulations have been performed to assess the expected background contribution from the LZ cryostat with this radioactivity. In 1,000 days of WIMP search exposure of a 5.6-tonne fiducial mass, the cryostat will contribute only a mean background of 0.160 +/- 0.001(stat) +/- 0.030(sys) counts. |
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Address |
[Akerib, D. S.; Biesiadzinski, T. P.; Bramante, R.; Craddock, W. W.; Ignarra, C. M.; Ji, W.; Krebs, H. J.; Lee, C.; Linehan, R. E.; Luitz, S.; Mizrachi, E.; Monzani, M. E.; Ratcliff, B. N.; Shutt, T. A.; Skarpaas, K.; To, W. H.; Va'vra, J.; Whitis, T. J.; Wisniewski, W. J.] SLAC Natl Accelerator Lab, POB 20450, Stanford, CA 94309 USA, Email: sally.shaw.13@ucl.ac.uk; |
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Corporate Author |
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Thesis |
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Publisher |
Elsevier Science Bv |
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English |
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ISSN |
0927-6505 |
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Notes |
WOS:000416185400001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial ![sorted by Serial field, descending order (down)](img/sort_desc.gif) |
3384 |
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Permanent link to this record |