Department of Physics & Astronomy

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125 GeV Higgs Boson and the Type-II Seesaw Model
(Published for SISSA by Springer, 2013-03) Okada, Nobuchika; University of Alabama Tuscaloosa
We study the vacuum stability and unitarity conditions for a 125 GeV Standard Model (SM)-like Higgs boson mass in the type-II seesaw model. We find that, as long as the seesaw scale is introduced below the SM vacuum instability bound, there exists a large parameter space predicting a 125 GeV Higgs mass, irrespective of the exact value of the seesaw scale, satisfying both stability and unitarity conditions up to the Planck scale. We also study the model predictions for the Higgs partial decay widths in the diphoton and Z+photon channels with respect to their SM expectations and find that the decay rates for these two processes are anti- correlated. We further show that for any given enhancement in the Higgs-to-diphoton rate over its SM expectation, there exists an upper bound on the type-II seesaw scale, and hence, on the masses of the associated doubly- and singly-charged Higgs bosons in the allowed parameter space. For instance, if more than 10% enhancement persists in the Higgs-to-diphoton channel, the upper limit on the type-II seesaw scale is about 450 GeV which is completely within the reach of the 14 TeV LHC. We believe this to be an encouraging result for the experimental searches of the singly- and doubly-charged Higgs bosons which, in combination with improved sensitivity in the Higgs-to-diphoton and Higgs-to-Z+photon channels, could probe the entire allowed parameter space of the minimal type-II seesaw model, and establish/eliminate it as a single viable extension of the SM.
125 GeV Higgs Boson Mass and Muon g−2 in 5D MSSM
(2016-10-26) Okada, Nobuchika; University of Alabama Tuscaloosa
In the minimal supersymmetric standard model (MSSM), the tension between the observed Higgs boson mass and the experimental result of the muon g − 2 measurement requires a large mass splitting between stops and smuons/charginos/neutralinos. We consider a five-dimensional (5D) framework of the MSSM with the Randall-Sundrum warped background metric, and show that such a mass hierarchy is naturally achieved in terms of geometry. In our setup, the supersymmetry is broken at the ultraviolet (UV) brane, while all the MSSM multiplets reside in the 5D bulk. An appropriate choice of the bulk mass parameters for the MSSM matter multiplets can naturally realize the sparticle mass hierarchy desired to resolve the tension. The gravitino is localized at the UV brane and hence becomes very heavy, while the gauginos spreading over the bulk acquire their masses suppressed by the fifth dimensional volume. As a result, the lightest sparticle neutralino is a candidate for the dark matter as usual in the MSSM. In addition to reproducing the SM-like Higgs boson mass of around 125 GeV and the measured value of the muon g − 2, we consider a variety of phenomenological constraints, and present the benchmark particle mass spectra that can be explored at the LHC Run-2 in the near future.
125 gev higgs boson mass from 5d gauge-higgs unification
(University of Alabama Libraries, 2015) Carson, Jason Carl; Okada, Nobuchika; University of Alabama Tuscaloosa
In the context of a simple gauge-Higgs unification (GHU) scenario based on the gauge group SU(3)×U(1)′ in a 5-dimensional flat space-time, we investigate a possibility to reproduce the observed Higgs boson mass of around 125 GeV. We introduce bulk fermion multiplets with a bulk mass and a (half) periodic boundary condition. In our analysis, we adopt a low energy effective theoretical approach of the GHU scenario, where the running Higgs quartic coupling is required to vanish at the compactification scale. Under this "gauge-Higgs condition," we investigate the renormalization group evolution of the Higgs quartic coupling and find a relation between the bulk mass and the compactification scale so as to reproduce the 125 GeV Higgs boson mass. Through quantum corrections at the one-loop level, the bulk fermions contribute to the Higgs boson production and decay processes and deviate the Higgs boson signal strengths at the Large Hadron Collider (LHC) experiments from the Standard Model (SM) predictions. Employing the current experimental data which show the the Higgs boson signal strengths for a variety of Higgs decay modes are consistent with the SM predictions, we obtain lower mass bounds on the lightest mode of the bulk fermions.
125 GeV Higgs boson mass from 5D gauge-Higgs unification
(Oxford University Press, 2018) Carson, Jason; Okada, Nobuchika; University of Alabama Tuscaloosa
In the context of a simple gauge-Higgs unification (GHU) scenario based on the gauge group SU(3) x U(1)' in a 5D flat space-time, we investigate the possibility of reproducing the observed Higgs boson mass of around 125 GeV. We introduce bulk fermion multiplets with a bulk mass and a (half-)periodic boundary condition. In our analysis, we adopt a low-energy effective theoretical approach of the GHU scenario, where the running Higgs quartic coupling is required to vanish at the compactification scale. Under this “gauge-Higgs condition,” we investigate the renormalization group evolution of the Higgs quartic coupling and find a relation between the bulk mass and the compactification scale so as to reproduce the 125 GeV Higgs boson mass. Through quantum corrections at the one-loop level, the bulk fermions contribute to the Higgs boson production and decay processes and deviate the Higgs boson signal strengths at the Large Hadron Collider experiments from the Standard Model (SM) predictions. Employing the current experimental data that show that the Higgs boson signal strengths for a variety of Higgs decay modes are consistent with the SM predictions, we obtain lower mass bounds on the lightest mode of the bulk fermions to be around 1 TeV.
125 GeV Higgs, type III seesaw and gauge-Higgs unification
(Elsevier, 2012-09-17) He, Bin; Okada, Nobuchika; Shafi, Qaisar; University of Delaware; University of Alabama Tuscaloosa
Recently, both the ATLAS and CMS experiments have observed an excess of events that could be the first evidence for a 125 GeV Higgs boson. This is a few GeV below the (absolute) vacuum stability bound on the Higgs mass in the Standard Model (SM), assuming a Planck mass ultraviolet (UV) cutoff. In this Letter, we study some implications of a 125 GeV Higgs boson for new physics in terms of the vacuum stability bound. We first consider the seesaw extension of the SM and find that in type III seesaw, the vacuum stability bound on the Higgs mass can be as low as 125 GeV for the seesaw scale around a TeV. Next we discuss some alternative new physics models which provide an effective ultraviolet cutoff lower than the Planck mass. An effective cutoff Lambda similar or equal to 10(11) GeV leads to a vacuum stability bound on the Higgs mass of 125 GeV. In a gauge-Higgs unification scenario with five-dimensional flat spacetime, the so-called gauge-Higgs condition can yield a Higgs mass of 125 GeV, with the compactification scale of the extra-dimension being identified as the cutoff scale Lambda similar or equal to 10(11) GeV. Identifying the compactification scale with the unification scale of the SM SU(2) gauge coupling and the top quark Yukawa coupling yields a Higgs mass of 121 +/- 2 GeV. (C) 2012 Elsevier B.V. All rights reserved.
A 2 hour quasi period in an ultraluminous X-ray source in NGC 628
(IOP Publishing, 2005-03-01) Liu, JF; Bregman, JN; Lloyd-Davies, E; Irwin, J; Espaillat, C; Seitzer, P; University of Michigan System; University of Michigan; University of Alabama Tuscaloosa
Quasi-periodic oscillations and X-ray spectroscopy are powerful probes of black hole masses and accretion disks, and here we apply these diagnostics to an ultraluminous X-ray source (ULX) in the spiral galaxy NGC 628 (M74). This object was observed four times over 2 years with the Chandra X-Ray Observatory and XMM-Newton, with three long observations showing dramatic variability, distinguished by a series of outbursts with a quasi period of 4000-7000 s. This is unique behavior among ULXs and Galactic X-ray binaries because of the combination of its burstlike peaks and deep troughs, its long quasi periods, its high variation amplitudes of >90%, and its substantial variability between observations. The X-ray spectra is fitted by an absorbed accretion disk plus a power-law component, suggesting the ULX was in a spectral state analogous to the low/hard state or the very high state of Galactic black hole X-ray binaries. A black hole mass of similar to(2-20) x 10(3) M-circle dot is estimated from the f(b)-M-circle scaling relation found in the Galactic X- ray binaries and active galactic nuclei.
The 2005 November outburst in OJ 287 and the binary black hole model
(IOP Publishing, 2006-05-20) Valtonen, M. J.; Nilsson, K.; Sillanpaa, A.; Takalo, L. O.; Lehto, H. J.; Keel, W. C.; Haque, S.; Cornwall, D.; Mattingly, A.; University of Turku; University West Indies Mona Jamaica; University West Indies Saint Augustine; University of Alabama Tuscaloosa
We report observations of the largest optical outburst in 20 years in the quasar OJ 287. In some ways it was expected, due to the well-known quasi-periodic 12 yr outburst cycle of OJ 287. In other ways the timing of the outburst was surprising, since calculations based on the periodicity were predicting such an outburst in late 2006. Here we point out that, in the precessing binary black hole model, first proposed by Sillanpaa et al., and later refined by Lehto & Valtonen and Sundelius et al., the precession shifts the first outburst of each outburst season progressively to earlier times relative to the mean period. Thus, in this model, the timing of the outburst is quite acceptable, even if it was not predicted. The next test of the model comes in 2007 September when the second brightness peak is due. It may then be possible to detect the shortening of the binary period due to emission of gravitational waves from the system.
A ~3.8 hr Periodicity From an Ultrasoft Active Galactic Nucleus Candidate
(2013-10-10) Lin, Dacheng; Irwin, Jimmy A.; Godet, Olivier; Webb, Natalie A.; Barret, Didier; University of Alabama Tuscaloosa
3rd Karl Schwarzschild Meeting – Gravity and the Gauge/Gravity Correspondence, 24-28 July 2017, Frankfurt am Main, Germany
(2017) Nicolini, Piero; Kaminski, Matthias; Mureika, Jonas; Bleicher, Marcus; University of Alabama Tuscaloosa
A 3x2 texture for neutrino oscillations and leptogenesis
(Elsevier, 2008-03-06) Brahmachari, Biswajoy; Okada, Nobuchika; High Energy Accelerator Research Organization (KEK); University of Alabama Tuscaloosa
In an economical system with only two heavy right-handed neutrinos, we postulate a new texture for 3 x 2 Dirac mass matrix m(D). This model implies one massless light neutrino and thus displays only two patterns of mass spectrum for light neutrinos, namely hierarchical or inverse-hierarchical. Both the cases can correctly reproduce all the current neutrino oscillation data with a unique prediction m(nu e nu e) = root Delta m(solar)(2)/3 and root Delta(2)(atm) for the hierarchical and the inverse-hierarchical cases, respectively, which can be tested in next generation neutrino-less double beta decay experiments. Introducing a single physical CP phase in in m(D), we examine baryon asymmetry through leptogenesis. Interestingly, through the CP phase there are correlations between the amount of baryon asymmetry and neutrino oscillation parameters. We find that for a fixed CP phase, the hierarchical case also succeeds in generating the observed baryon asymmetry in our universe, plus a non-vanishing U-e3 which is accessible in future baseline neutrino oscillation experiments. (c) 2008 Published by Elsevier B.V.
4D Edge Currents from 5D Chem-Simons Theory
(Elsevier, 1995-05-22) Gupta, K. S.; Stern, Allen; University of Alabama Tuscaloosa
A class of two dimensional conformal field theories is known to correspond to three dimensional Chem-Simons theory. Here we claim that there is an analogous class of four dimensional field theories corresponding to five dimensional Chem-Simons theory. The four dimensional theories give a coupling between a scalar field and an external divergenceless vector field and they may have some application in magnetohydrodynamics. Like in conformal theories they possess a diffeomorphism symmetry, which for us is along the direction of the vector field, and their generators are analogous to Virasoro generators. Our analysis of the abelian Chem-Simons system uses elementary canonical methods for the quantization of field theories defined on manifolds with boundaries. Edge states appear for these systems and they yield a four dimensional current algebra. We examine the quantization of these algebras in several special cases and claim that a renormalization of the 5D Chem-Simons coupling is necessary for removing divergences.
About AGN ionization echoes, thermal echoes and ionization deficits in low-redshift Ly alpha blobs
(Oxford University Press, 2016-07-28) Schirmer, Mischa; Malhotra, Sangeeta; Levenson, Nancy A.; Fu, Hai; Davies, Rebecca L.; Keel, William C.; Torrey, Paul; Bennert, Vardha N.; Pancoast, Anna; Turner, James E. H.; Arizona State University; Arizona State University-Tempe; University of Iowa; Australian National University; University of Alabama Tuscaloosa; Harvard University; Smithsonian Astrophysical Observatory; Smithsonian Institution; Massachusetts Institute of Technology (MIT); California State University System; California Polytechnic State University San Luis Obispo
We report the discovery of 14 Ly alpha blobs (LABs) at z similar to 0.3, existing at least 4-7 billion years later in the Universe than all other LABs known. Their optical diameters are 20-70 kpc, and GALEX data imply Ly alpha luminosities of (0.4-6.3) x 10(43) erg s(-1). Contrary to high-z LABs, they live in low-density areas. They are ionized by AGN, suggesting that cold accretion streams as a power source must deplete between z = 2 and 0.3. We also show that transient AGN naturally explain the ionization deficits observed in many LABs. Their Ly alpha and X-ray fluxes decorrelate below less than or similar to 10(6) years because of the delayed escape of resonantly scattering Ly alpha photons. High Ly alpha luminosities do not require currently powerful AGN, independent of obscuration. Chandra X-ray data reveal intrinsically weak AGN, confirming the luminous optical nebulae as impressive ionization echoes. For the first time, we also report mid-infrared thermal echoes from the dusty tori. We conclude that the AGN have faded by three to four orders of magnitude within the last 10(4-5) years, leaving fossil UV, optical and thermal radiation behind. The host galaxies belong to the group of previously discovered Green Bean galaxies (GBs). Gemini optical imaging reveals smooth spheres, mergers, spectacular outflows and ionization cones. Because of their proximity and high flux densities, GBs are perfect targets to study AGN feedback, mode switching and the Ly alpha escape. The fully calibrated, co-added optical FITS images are publicly available.
Absence of the Holographic Principle in Noncommutative Chern-Simons Theory
(2001-12-03) Pinzul, A.; Stern, Allen; University of Alabama Tuscaloosa
We examine noncommutative Chern-Simons theory on a bounded spatial domain. We argue that upon `turning on' the noncommutativity, the edge observables, which characterized the commutative theory, move into the bulk. We show this to lowest order in the noncommutativity parameter appearing in the Moyal star product. If one includes all orders, the hamiltonian formulation of the gauge theory ceases to exist, indicating that the Moyal star product must be modified in the presence of a boundary. Alternative descriptions are matrix models. We examine one such model, obtained by a simple truncation of Chern-Simons theory on the noncommutative plane, and express its observables in terms of Wilson lines.
Abstract: E5.00005 : Spin and Orbital Magnetic Moments of Fe and Co in Co/Fe and Fe/Co Multilayers on Si from L2,3 Edge X-ray Magnetic Circular Dichroism Spectroscopy*
(2016) Mankey, Gary; University of Alabama Tuscaloosa
Nanostructured FeCo thin films are interesting for magnetic recording applications due to their high saturation magnetization, high Curie temperature and low magnetocrystalline anisotropy. It is desirable to know how the magnetism is modified by the nanostructrure. We report Fe L₂,₃ edge and Co L₂,₃ edge x-ray magnetic circular dichroism (XMCD) investigations of element specific spin and orbital magnetism of Fe and Co in two multilayer samples: (S1) Si/SiO2/[Co 0.8 nm/Fe 1.6 nm]x32/W (2nm) and (S2) Si/SiO2/[Co 1.6 nm/Fe 0.8 nm]x32/W (2nm) thin films at room temperature. Sum rule analysis of XMCD at Fe L₂,₃ edge in sample S1 shows that the orbital moment of Fe is strongly enhanced and the spin moment is strongly reduced as compared to the values found in bulk Fe. Details of sum rule analysis will be presented to compare and contrast spin magnetic moments and orbital magnetic moments of Fe and Co in the two multilayer samples.
Abstract: H29.00006 : The Quality Enhancement Plan Matrix (12 Years and Still Tweaking the Process!)
(2009) Mankey, Gary; University of Alabama Tuscaloosa
As an alumni of the 1997 New Faculty Workshop, I've had plenty of opportunities to experiment with the teaching methods introduced there. Most recently, faculty at UA have been asked to develop a Learner-Centered approach to teaching, where regular, timely and thorough assesments of student learning becomes a key component of the curriculum. This involves four phases: 1) Identifying and defining learning outcomes, 2) Matching assessments to outcomes, 3) Identifying baselines and progression toward benchmarks and 4) Documenting the process using a quality enhancement plan matrix. This has led to the development of learning tools designed to enhance critical thinking and problem solving skills. This will be discussed in the context of setting teaching goals for new faculty, including how to document the process for teaching portfolios.
Accelerated Design of Novel Heusler Compounds for Spintronics Applications
(University of Alabama Libraries, 2021) KC, Shambhu; LeClair, Patrick; University of Alabama Tuscaloosa
Material discovery could be defined as the identification of a previously unexplored phases/composition which may exhibit properties that are unique or similar to that of previously explored composition. Historically, this has relied to some extent on serendipity. With the search space getting wider and at the same time an increased global competitiveness, it has become apparent that the material discovery process can be accelerated, which also helps in reducing cost. Spintronics, which utilizes both the spin and charge of an electron, is a technology that has the promise to take over existing charge-based technology. Half-metallic ferromagnets, due to their ability to generate 100% spin polarization, are considered ideal materials to be used in spintronic devices. While many candidate half-metals have been predicted based on theoretical calculations, finding a half-metallic character in experiments is still an open challenge. This provides impetus to search for new candidate materials with robust half-metallic character. In this dissertation, a new substitution scheme has been realized that allows for the design of many new functional materials in a relatively short time. It is also shown that, in many cases, alloy properties can be tuned by counting the total number of valence electrons, which is less dependent on the substitution scheme. Another approach, which paves the way to enhance the magnetic properties of the materials is also discussed. Hence with the identification of new approaches to material design, this dissertation adds value in the quest for the accelerated design of functional materials.
Active nuclei and star-forming objects at z > 2: Metallicities, winds, and formation histories
(University of Chicago Press, 2002-06) Keel, WC; Wu, WT; Waddington, I; Windhorst, RA; Pascarelle, SM; University of Alabama Tuscaloosa; Arizona State University; Arizona State University-Tempe
We present near-infrared observations of the active galactic nuclei (AGNs) and star-forming objects in the field of the radio galaxy 53W002 at z = 2.39. The star-forming objects are of special interest as candidate protogalactic objects. The 1.1-2.2 mum passbands sample the emitted-optical range at this redshift, providing new diagnostics of the structure, metal abundance, and age of the members of this grouping originally selected through Lyalpha emission. The star-forming objects are uniformly very blue in continuum slope, which fits with the strong Lyalpha emission in indicating metal abundances that are less than half solar; some are as blue as the most metal-poor local objects. They fall in a range of luminosity and metallicity that is not populated by local objects, indicating a shorter star-forming history at this early epoch. The best local analogs, such as Mrk 66 and 357, either have several times lower luminosity at comparable [O/H] or significantly higher [O/H] for comparable luminosity. Spectroscopy from the Near-Infrared Camera and Multi-Object Spectrometer yields detections of [O III] emission for two objects and interesting [O III] and Hbeta limits for the rest, augmented by Halpha limits from Infrared Telescope Facility imaging. These data are satisfied by model stellar populations that have been forming stars for the last 2-5 x 10(6) yr before z = 2.39. We do not see evidence for older preexisting stellar populations, either in the broadband colors or as redder halos in which the star-forming regions are imbedded. These results suggest that the compact star-forming objects we see at z = 2.0-2.5 are indeed early stages in the building of galaxies rather than transient star-forming events in larger pre-existing dynamical systems. The results also allow an alternative scheme, in which these are low-mass systems that are blowing winds rather than self-enriching, in which case they should fade rapidly with cosmic epoch. For the three prominent AGNs at z = 2.39, Halpha and [O III] emission were measured. Unlike the fainter star-forming objects, their line ratios (specifically Lyalpha/Halpha) show metallicities just as high as in nearby systems. If the AGNs occur in those systems that started with the highest density and began active star formation before the less massive surrounding objects, they will have higher metallicity ( as we see in their emitted-ultraviolet line ratios). The "ionization cones" seen prominently in Lyalpha also appear in [O III] and Halpha, with a role for continuum reflection in some cases as well. The contrast between the AGNs and fainter star-forming objects can be broadly accommodated in a hierarchical formation picture, although there are still important unknowns as to the fate of the star-forming objects.
AdS/CFT far from equilibrium in a Vaidya setup
(2017) Wondrak, Michael F.; Kaminski, Matthias; Nicolini, Piero; Bleicher, Marcus; University of Alabama Tuscaloosa
In this paper we apply the AdS/CFT correspondence to study a strongly coupled plasma far from equilibrium with a strong emphasis on the shear behavior. The plasma serves as a model for an electrically charged quark-gluon plasma. On the gravitational side, we use an ingoing Vaidya black brane spacetime. The highest rate of mass infall is confined to a short time interval.
AINUR: Atlas of Images of NUclear Rings
(Oxford University Press, 2010-03-11) Comeron, S.; Knapen, J. H.; Beckman, J. E.; Laurikainen, E.; Salo, H.; Martinez-Valpuesta, I.; Buta, R. J.; Instituto de Astrofisica de Canarias; Universidad de la Laguna; University of Oulu; University of Alabama Tuscaloosa
We present the most complete atlas of nuclear rings to date. We include 113 rings found in 107 galaxies, six of which are elliptical galaxies, five are highly inclined disc galaxies, 18 are unbarred disc galaxies and 78 are barred disc galaxies. Star-forming nuclear rings occur in 20 +/- 2 per cent of disc galaxies with types between T = -3 and T = 7. We aim to explore possible relationships between the size and morphology of the rings and various galactic parameters. We also aim to establish whether ultra-compact nuclear rings are a distinct population of nuclear rings or if they are merely the low-end tail of the nuclear ring size distribution. We produce colour index and structure maps, as well as H alpha and Pa alpha continuum-subtracted images from Hubble Space Telescope archival data. We derive ellipticity profiles from H-band Two-Micron All-Sky Survey images in order to detect bars and find their metric parameters. We measure the non-axisymmetric torque parameter, Q(g), and search for correlations between bar and ring metric parameters, and Q(g). Our atlas of nuclear rings includes star-forming and dust rings. Nuclear rings span a range from a few tens of parsecs to a few kiloparsecs in radius. Star-forming nuclear rings can be found in a wide range of morphological types, from S0 to Sd, with a peak in the distribution between Sab and Sb and without strong preference for barred galaxies. The ellipticities of rings found in disc galaxies range from c(r) = 0 to c(r) = 0.4, assuming that nuclear rings lie in the galactic plane. Dust nuclear rings are found in elliptical and S0 galaxies. For barred galaxies, the maximum radius that a nuclear ring can reach is a quarter of the bar radius. We found a nearly random distribution of position angle offsets between nuclear rings and bars. There is some evidence that nuclear ring ellipticity is limited by bar ellipticity. We confirm that the maximum relative size of a star-forming nuclear ring is inversely proportional to the non-axisymmetric torque parameter, Q(g) ('stronger bars host smaller rings') and that the origin of nuclear rings, even the ones in non-barred hosts, is closely linked to the existence of dynamical resonances. Ultra-compact nuclear rings constitute the low-radius portion of the nuclear ring size distribution. We discuss implications for the lifetimes of nuclear rings and for their origin and evolution.
All-flavour search for neutrinos from dark matter annihilations in the Milky Way with IceCube/DeepCore
(Springer, 2016) IceCube Collaboration; Palczewski, T.; Pepper, J.A.; Toale, P.A.; Williams, D.R.; RWTH Aachen University; University of Adelaide; University of Alaska System; University of Alaska Anchorage; Clark Atlanta University; University System of Georgia; Georgia Institute of Technology; Southern University System; Southern University & A&M College; University of California System; University of California Berkeley; United States Department of Energy (DOE); Lawrence Berkeley National Laboratory; Humboldt University of Berlin; Ruhr University Bochum; University of Bonn; Universite Libre de Bruxelles; Vrije Universiteit Brussel; Massachusetts Institute of Technology (MIT); Chiba University; University of Canterbury; University System of Maryland; University of Maryland College Park; University System of Ohio; Ohio State University; University of Copenhagen; Niels Bohr Institute; Dortmund University of Technology; Michigan State University; University of Alberta; University of Erlangen Nuremberg; University of Geneva; Ghent University; University of California Irvine; University of Kansas; University of Wisconsin System; University of Wisconsin Madison; Johannes Gutenberg University of Mainz; Marquette University; University of Mons; National Research Nuclear University MEPhI (Moscow Engineering Physics Institute); Technical University of Munich; University of Munster; University of Delaware; Yale University; University of Oxford; Drexel University; South Dakota School Mines & Technology; Oskar Klein Centre; Stockholm University; State University of New York (SUNY) System; State University of New York (SUNY) Stony Brook; Sungkyunkwan University (SKKU); University of Toronto; University of Alabama Tuscaloosa; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Rochester; Uppsala University; University of Wuppertal; Helmholtz Association; Deutsches Elektronen-Synchrotron (DESY)
We present the first IceCube search for a signal of dark matter annihilations in the Milky Way using all-flavour neutrino-induced particle cascades. The analysis focuses on the DeepCore sub-detector of IceCube, and uses the surrounding IceCube strings as a veto region in order to select starting events in the DeepCore volume. We use 329 live-days of data from IceCube operating in its 86-string configuration during 2011-2012. No neutrino excess is found, the final result being compatible with the background-only hypothesis. From this null result, we derive upper limits on the velocity-averaged self-annihilation cross-section, \(\langle \sigma_A v\rangle\), for dark matter candidate masses ranging from 30 GeV up to 10 TeV, assuming both a cuspy and a flat-cored dark matter halo profile. For dark matter masses between 200 GeV and 10 TeV, the results improve on all previous IceCube results on \(\langle \sigma_A v\rangle\), reaching a level of 10⁻²³ cm³ s⁻¹, depending on the annihilation channel assumed, for a cusped NFW profile. The analysis demonstrates that all-flavour searches are competitive with muon channel searches despite the intrinsically worse angular resolution of cascades compared to muon tracks in IceCube.

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