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Author Escudero, M.; Hooper, D.; Witte, S.J. url  doi
openurl 
  Title Updated collider and direct detection constraints on Dark Matter models for the Galactic Center gamma-ray excess Type Journal Article
  Year 2017 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 02 Issue 2 Pages 038 - 21pp  
  Keywords dark matter experiments; dark matter theory  
  Abstract Utilizing an exhaustive set of simplified models, we revisit dark matter scenarios potentially capable of generating the observed Galactic Center gamma-ray excess, updating constraints from the LUX and PandaX- II experiments, as well as from the LHC and other colliders. We identify a variety of pseudoscalar mediated models that remain consistent with all constraints. In contrast, dark matter candidates which annihilate through a spin-1 mediator are ruled out by direct detection constraints unless the mass of the mediator is near an annihilation resonance, or the mediator has a purely vector coupling to the dark matter and a purely axial coupling to Standard Model fermions. All scenarios in which the dark matter annihilates throught-channel processes are now ruled out by a combination of the constraints from LUX/ PandaX-II and the LHC.  
  Address [Escudero, Miguel] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, Apartado Correos 22085, E-46071 Valencia, Spain, Email: miguel.escudero@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000399455000038 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3079  
Permanent link to this record
 
 
Author Escudero, M.; Witte, S.J.; Hooper, D. url  doi
openurl 
  Title Hidden sector dark matter and the Galactic Center gamma-ray excess: a closer look Type Journal Article
  Year 2017 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 11 Issue 11 Pages 042 - 29pp  
  Keywords dark matter experiments; dark matter theory  
  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.  
  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;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000417561900005 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3412  
Permanent link to this record
 
 
Author Gelmini, G.B.; Huh, J.H.; Witte, S.J. url  doi
openurl 
  Title Unified halo-independent formalism from convex hulls for direct dark matter searches Type Journal Article
  Year 2017 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 12 Issue 12 Pages 039 - 33pp  
  Keywords dark matter experiments; dark matter theory  
  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.  
  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;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000418922000002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3440  
Permanent link to this record
 
 
Author Gelmini, G.B.; Takhistov, V.; Witte, S.J. url  doi
openurl 
  Title Casting a wide signal net with future direct dark matter detection experiments Type Journal Article
  Year 2018 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 07 Issue 7 Pages 009 - 55pp  
  Keywords dark matter detectors; dark matter experiments; dark matter theory  
  Abstract As dark matter (DM) direct detection experiments continue to improve their sensitivity they will inevitably encounter an irreducible background arising from coherent neutrino scattering. This so-called “neutrino floor” may significantly reduce the sensitivity of an experiment to DM-nuclei interactions, particularly if the recoil spectrum of the neutrino background is approximately degenerate with the DM signal. This occurs for the conventionally considered spin-independent (SI) or spin-dependent (SD) interactions. In such case, an increase in the experiment's exposure by multiple orders of magnitude may not yield any significant increase in sensitivity. The typically considered SI and SD interactions, however, do not adequately reflect the whole landscape of the well-motivated DM models, which includes other interactions. Since particle DM has not been detected yet in laboratories, it is essential to understand and maximize the detection capabilities for a broad variety of possible models and signatures. In this work we explore the impact of the background arising from various neutrino sources on the discovery potential of a DM signal for a large class of viable DM-nucleus interactions and several potential futuristic experimental settings, with different target elements. For some momentum suppressed cross sections, large DM particle masses and heavier targets, we find that there is no suppression of the discovery limits due to neutrino backgrounds. Further, we explicitly demonstrate that inelastic scattering, which could appear in models with multicomponent dark sectors, would help to lift the signal degeneracy associated with the neutrino floor. This study could assist with mapping out the optimal DM detection strategy for the next generation of experiments.  
  Address [Gelmini, Graciela B.; Takhistov, Volodymyr; Witte, Samuel J.] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA, Email: gelmini@physics.ucla.edu;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000437422800001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3646  
Permanent link to this record
 
 
Author Escudero, M.; Witte, S.J.; Rius, N. url  doi
openurl 
  Title The dispirited case of gauged U(1)(B-L) dark matter Type Journal Article
  Year 2018 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 08 Issue 8 Pages 190 - 30pp  
  Keywords Beyond Standard Model; Cosmology of Theories beyond the SM  
  Abstract We explore the constraints and phenomenology of possibly the simplest scenario that could account at the same time for the active neutrino masses and the dark matter in the Universe within a gauged U(1)(B-L) symmetry, namely right-handed neutrino dark matter. We find that null searches from lepton and hadron colliders require dark matter with a mass below 900 GeV to annihilate through a resonance. Additionally, the very strong constraints from high-energy dilepton searches fully exclude the model for 150 GeV < m(z') < 3 TeV. We further explore the phenomenology in the high mass region (i.e. masses greater than or similar to O(1) TeV) and highlight theoretical arguments, related to the appearance of a Landau pole or an instability of the scalar potential, disfavoring large portions of this parameter space. Collectively, these considerations illustrate that a minimal extension of the Standard Model via a local U(1)(B-L) symmetry with a viable thermal dark matter candidate is difficult to achieve without fine-tuning. We conclude by discussing possible extensions of the model that relieve tension with collider constraints by reducing the gauge coupling required to produce the correct relic abundance.  
  Address [Escudero, Miguel] Univ Valencia, CSIC, Dept Fis Teor, C Catedrat Jose Beltran 2, E-46980 Paterna, Spain, Email: Miguel.Escudero@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1029-8479 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000443008100006 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 3706  
Permanent link to this record
 
 
Author Caputo, A.; Pena-Garay, C.; Witte, S.J. url  doi
openurl 
  Title Looking for axion dark matter in dwarf spheroidal galaxies Type Journal Article
  Year 2018 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 98 Issue 8 Pages 083024 - 6pp  
  Keywords  
  Abstract We study the extent to which the decay of cold dark matter axions can be probed with forthcoming radio telescopes such as the Square Kilometer Array (SKA). In particular, we focus on signals arising from dwarf spheroidal galaxies, where astrophysical uncertainties are reduced and the expected magnetic field strengths are such that signals arising from axion decay may dominate over axion-photon conversion in a magnetic field. We show that with similar to 100 hr of observing time, SKA could improve current sensitivity by 2-3 orders of magnitude-potentially obtaining sufficient sensitivity to begin probing the decay of cold dark matter axions.  
  Address [Caputo, Andrea; Witte, Samuel J.] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, Apartado Correos 22085, E-46071 Valencia, Spain  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000448458600001 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 3788  
Permanent link to this record
 
 
Author Caputo, A.; Regis, M.; Taoso, M.; Witte, S.J. url  doi
openurl 
  Title Detecting the stimulated decay of axions at radio frequencies Type Journal Article
  Year 2019 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 03 Issue 3 Pages 027 - 22pp  
  Keywords axions; dark matter theory; dark matter detectors; dwarfs galaxies  
  Abstract Assuming axion-like particles account for the entirety of the dark matter in the Universe, we study the possibility of detecting their decay into photons at radio frequencies. We discuss different astrophysical targets, such as dwarf spheroidal galaxies, the Galactic Center and halo, and galaxy clusters. The presence of an ambient radiation field leads to a stimulated enhancement of the decay rate; depending on the environment and the mass of the axion, the effect of stimulated emission may amplify the photon flux by serval orders of magnitude. For axion-photon couplings allowed by astrophysical and laboratory constraints (and possibly favored by stellar cooling), we find the signal to be within the reach of next-generation radio telescopes such as the Square Kilometer Array.  
  Address [Caputo, Andrea; Witte, Samuel J.] Univ Valencia, CSIC, Inst Fis Corpuscular, Apartado Correos 22085, E-46071 Valencia, Spain, Email: andrea0292@hotmail.it;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000461450100002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3944  
Permanent link to this record
 
 
Author Gelmini, G.B.; Takhistov, V.; Witte, S.J. url  doi
openurl 
  Title Geoneutrinos in large direct detection experiments Type Journal Article
  Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 99 Issue 9 Pages 093009 - 11pp  
  Keywords  
  Abstract Geoneutrinos can provide a unique insight into Earth's interior, its central engine, and its formation history. We study the detection of geoneutrinos in large direct detection experiments, which has been considered nonfeasible. We compute the geoneutrino-induced electron and nuclear recoil spectra in different materials, under several optimistic assumptions. We identify germanium as the most promising target element due to the low nuclear recoil energy threshold that could be achieved. The minimum exposure required for detection would be O(10) ton-years. The realistic low thresholds achievable in germanium and silicon permit the detection of K-40 geoneutrinos. These are particularly important to determining Earth's formation history, but they are below the kinematic threshold of inverse beta decay, the detection process used in scintillator-based experiments.  
  Address [Gelmini, Graciela B.; Takhistov, Volodymyr] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA, Email: gelmini@physics.ucla.edu;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000469022000001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4024  
Permanent link to this record
 
 
Author Mena, O.; Palomares-Ruiz, S.; Villanueva-Domingo, P.; Witte, S.J. url  doi
openurl 
  Title Constraining the primordial black hole abundance with 21-cm cosmology Type Journal Article
  Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 100 Issue 4 Pages 043540 - 23pp  
  Keywords  
  Abstract The discoveries of a number of binary black hole mergers by LIGO and VIRGO have reinvigorated the interest that primordial black holes (PBHs) of tens of solar masses could contribute non-negligibly to the dark matter energy density. Should even a small population of PBHs with masses greater than or similar to O(M-circle dot) exist, they could profoundly impact the properties of the intergalactic medium and provide insight into novel processes at work in the early Universe. We demonstrate here that observations of the 21-cm transition in neutral hydrogen during the epochs of reionization and cosmic dawn will likely provide one of the most stringent tests of solar mass PBHs. In the context of 21-cm cosmology, PBHs give rise to three distinct observable effects: (i) the modification to the primordial power spectrum (and thus also the halo mass function) induced by Poisson noise, (ii) a uniform heating and ionization of the intergalactic medium via x-rays produced during accretion, and (iii) a local modification to the temperature and density of the ambient medium surrounding isolated PBHs. Using a four-parameter astrophysical model, we show that experiments like SKA and HERA could potentially improve upon existing constraints derived using observations of the cosmic microwave background by more than 1 order of magnitude.  
  Address [Mena, Olga; Palomares-Ruiz, Sergio; Villanueva-Domingo, Pablo; Witte, Samuel J.] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, Apartado Correos 22085, E-46071 Valencia, Spain  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000483047300003 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 4122  
Permanent link to this record
 
 
Author Blanco, C.; Escudero, M.; Hooper, D.; Witte, S.J. url  doi
openurl 
  Title Z ' mediated WIMPs: dead, dying, or soon to be detected? Type Journal Article
  Year 2019 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 11 Issue 11 Pages 024 - 48pp  
  Keywords dark matter theory; dark matter detectors; dark matter experiments  
  Abstract Although weakly interacting massive particles (WIMPs) have long been among the most studied and theoretically attractive classes of candidates for the dark matter of our universe, the lack of their detection in direct detection and collider experiments has begun to dampen enthusiasm for this paradigm. In this study, we set out to appraise the status of the WIMP paradigm, focusing on the case of dark matter candidates that interact with the Standard Model through a new gauge boson. After considering a wide range of Z' mediated dark matter models, we quantitatively evaluate the fraction of the parameter space that has been excluded by existing experiments, and that is projected to fall within the reach of future direct detection experiments. Despite the existence of stringent constraints, we find that a sizable fraction of this parameter space remains viable. More specifically, if the dark matter is a Majorana fermion, we find that an order one fraction of the parameter space is in many cases untested by current experiments. Future direct detection experiments with sensitivity near the irreducible neutrino floor will be able to test a significant fraction of the currently viable parameter space, providing considerable motivation for the next generation of direct detection experiments.  
  Address [Blanco, Carlos] Univ Chicago, Dept Phys, Chicago, IL 60637 USA, Email: carlosblanco2718@uchicago.ed;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000507259700021 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4255  
Permanent link to this record
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