arXiv subjects

S. Profumo

Publications and source records attributed to S. Profumo.

At least 19 recordsLinked to original sources

arXiv2020

Right-handed Neutrino Dark Matter, Neutrino Masses, and non-Standard Cosmology in a 2HDM

We explore the dark matter phenomenology of a weak-scale right-handed neutrino in the context of a Two Higgs Doublet Model. The expected signal at direct detection experiments is different from the usual spin-independent and spin-dependent classification since the scattering with quarks depends on the dark matter spin. The dark matter relic density is set by thermal freeze-out and in the presence of non-standard cosmology, where an Abelian gauge symmetry is key for the dark matter production mechanism. We show that such symmetry allows us to simultaneously address neutrino masses and the flavor problem present in general Two Higgs Doublet Model constructions. Lastly, we outline the region of parameter space that obeys collider, perturbative unitarity and direct detection constraints.

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arXiv2020

Cosmic-ray Antinuclei as Messengers of New Physics: Status and Outlook for the New Decade

The precise measurement of cosmic-ray antinuclei serves as an important means for identifying the nature of dark matter and other new astrophysical phenomena, and could be used with other cosmic-ray species to understand cosmic-ray production and propagation in the Galaxy. For instance, low-energy antideuterons would provide a "smoking gun" signature of dark matter annihilation or decay, essentially free of astrophysical background. Studies in recent years have emphasized that models for cosmic-ray antideuterons must be considered together with the abundant cosmic antiprotons and any potential observation of antihelium. Therefore, a second dedicated Antideuteron Workshop was organized at UCLA in March 2019, bringing together a community of theorists and experimentalists to review the status of current observations of cosmic-ray antinuclei, the theoretical work towards understanding these signatures, and the potential of upcoming measurements to illuminate ongoing controversies. This review aims to synthesize this recent work and present implications for the upcoming decade of antinuclei observations and searches. This includes discussion of a possible dark matter signature in the AMS-02 antiproton spectrum, the most recent limits from BESS Polar-II on the cosmic antideuteron flux, and reports of candidate antihelium events by AMS-02; recent collider and cosmic-ray measurements relevant for antinuclei production models; the state of cosmic-ray transport models in light of AMS-02 and Voyager data; and the prospects for upcoming experiments, such as GAPS. This provides a roadmap for progress on cosmic antinuclei signatures of dark matter in the coming years.

astro-ph.HE↗

arXiv2014

Local Group dSph radio survey with ATCA (III): Constraints on Particle Dark Matter

We performed a deep search for radio synchrotron emissions induced by weakly interacting massive particles (WIMPs) annihilation or decay in six dwarf spheroidal (dSph) galaxies of the Local Group. Observations were conducted with the Australia Telescope Compact Array (ATCA) at 16 cm wavelength, with an rms sensitivity better than 0.05 mJy/beam in each field. In this work, we first discuss the uncertainties associated with the modeling of the expected signal, such as the shape of the dark matter (DM) profile and the dSph magnetic properties. We then investigate the possibility that point-sources detected in the proximity of the dSph optical center might be due to the emission from a DM cuspy profile. No evidence for an extended emission over a size of few arcmin (which is the DM halo size) has been detected. We present the associated bounds on the WIMP parameter space for different annihilation/decay final states and for different astrophysical assumptions. If the confinement of electrons and positrons in the dSph is such that the majority of their power is radiated within the dSph region, we obtain constraints on the WIMP annihilation rate which are well below the thermal value for masses up to few TeV. On the other hand, for conservative assumptions on the dSph magnetic properties, the bounds can be dramatically relaxed. We show however that, within the next 10 years and regardless of the astrophysical assumptions, it will be possible to progressively close in on the full parameter space of WIMPs by searching for radio signals in dSphs with SKA and its precursors.

astro-ph.CO↗

arXiv2014

Local Group dSph radio survey with ATCA (I): Observations and background sources

Dwarf spheroidal (dSph) galaxies are key objects in near-field cosmology, especially in connection to the study of galaxy formation and evolution at small scales. In addition, dSphs are optimal targets to investigate the nature of dark matter. However, while we begin to have deep optical photometric observations of the stellar population in these objects, little is known so far about their diffuse emission at any observing frequency, and hence on thermal and non-thermal plasma possibly residing within dSphs. In this paper, we present deep radio observations of six local dSphs performed with the Australia Telescope Compact Array at 16 cm wavelength. We mosaiced a region of radius of about one degree around three "classical" dSphs, Carina, Fornax, and Sculptor, and of about half of degree around three "ultra-faint" dSphs, BootesII, Segue2, and Hercules. The rms noise level is below 0.05 mJy for all the maps. The restoring beams FWHM ranged from 4.2 x 2.5 arcseconds to 30.0 x 2.1 arcseconds in the most elongated case. A catalogue including the 1392 sources detected in the six dSph fields is reported. The main properties of the background sources are discussed, with positions and fluxes of brightest objects compared with the FIRST, NVSS, and SUMSS observations of the same fields. The observed population of radio emitters in these fields is dominated by synchrotron sources. We compute the associated source number counts at 2 GHz down to fluxes of 0.25 mJy, which prove to be in agreement with AGN count models.

astro-ph.GA↗

arXiv2014

Local Group dSph radio survey with ATCA (II): Non-thermal diffuse emission

Our closest neighbours, the Local Group dwarf spheroidal (dSph) galaxies, are extremely quiescent and dim objects, where thermal and non-thermal diffuse emissions lack, so far, of detection. In order to possibly study the dSph interstellar medium, deep observations are required. They could reveal non-thermal emissions associated with the very-low level of star formation, or to particle dark matter annihilating or decaying in the dSph halo. In this work, we employ radio observations of six dSphs, conducted with the Australia Telescope Compact Array in the frequency band 1.1-3.1 GHz, to test the presence of a diffuse component over typical scales of few arcmin and at an rms sensitivity below 0.05 mJy/beam. We observed the dSph fields with both a compact array and long baselines. Short spacings led to a synthesized beam of about 1 arcmin and were used for the extended emission search. The high-resolution data mapped background sources, which in turn were subtracted in the short-baseline maps, to reduce their confusion limit. We found no significant detection of a diffuse radio continuum component. After a detailed discussion on the modelling of the cosmic-ray (CR) electron distribution and on the dSph magnetic properties, we present bounds on several physical quantities related to the dSphs, such that the total radio flux, the angular shape of the radio emissivity, the equipartition magnetic field, and the injection and equilibrium distributions of CR electrons. Finally, we discuss the connection to far-infrared and X-ray observations.

astro-ph.GA↗

arXiv2014

Planning the Future of U.S. Particle Physics (Snowmass 2013): Chapter 4: Cosmic Frontier

These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 4, on the Cosmic Frontier, discusses the program of research relevant to cosmology and the early universe. This area includes the study of dark matter and the search for its particle nature, the study of dark energy and inflation, and cosmic probes of fundamental symmetries.

hep-ex↗

arXiv2013

Cosmic Frontier Indirect Dark Matter Detection Working Group Summary

As part of the Snowmass process, the Cosmic Frontier Indirect-Detection subgroup (CF2) has drawn on input from the Cosmic Frontier and the broader Particle Physics community to produce this document. The purposes of this report are to identify opportunities for dark matter science through indirect detection, to give an overview of the primary scientific drivers for indirect searches for dark matter, and to survey current and planned experiments that have, as a large part of their scientific program, the goal of searching for indirect (or astrophysical) signatures of dark matter. We primarily address existing experiments with a large U.S. role, or future experiments where a U.S. contribution is sought. We also address the limitations of this technique, and answer the tough questions relevant to this subgroup posed by the HEP community through the Snowmass process.

astro-ph.HE↗

arXiv2011

The Impact of Recent Advances in Laboratory Astrophysics on our Understanding of the Cosmos

An emerging theme in modern astrophysics is the connection between astronomical observations and the underlying physical phenomena that drive our cosmos. Both the mechanisms responsible for the observed astrophysical phenomena and the tools used to probe such phenomena - the radiation and particle spectra we observe - have their roots in atomic, molecular, condensed matter, plasma, nuclear and particle physics. Chemistry is implicitly included in both molecular and condensed matter physics. This connection is the theme of the present report, which provides a broad, though non-exhaustive, overview of progress in our understanding of the cosmos resulting from recent theoretical and experimental advances in what is commonly called laboratory astrophysics. This work, carried out by a diverse community of laboratory astrophysicists, is increasingly important as astrophysics transitions into an era of precise measurement and high fidelity modeling.

astro-ph.IM↗

arXiv2011

Direct and Indirect Singlet Scalar Dark Matter Detection in the Lepton-Specific two-Higgs-doublet Model

A recent study of gamma-ray data from the Galactic Center motivates the investigation of light (~7-10 GeV) particle dark matter models featuring tau lepton pairs as dominant annihilation final state. The Lepton-Specific two-Higgs-doublet Model (2HDM-L) provides a natural framework where light, singlet scalar dark matter can pair-annihilate dominantly into tau leptons. We calculate the nucleon-dark matter cross section for singlet scalar dark matter within the 2HDM-L framework, and compare with recent results from direct detection experiments. We study how direct dark matter searches can be used to constrain the dark matter interpretation of gamma ray observations, for different dominant annihilation final states. We show that models exist with the correct thermal relic abundance that could fit the claimed gamma-ray excess from the Galactic Center region and have direct detection cross sections of the order of what needed to interpret recent anomalous events reported by direct detection experiments.

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arXiv2010

Dark Matter decay and annihilation in the Local Universe: CLUES from Fermi

We present all-sky simulated Fermi maps of gamma-rays from dark matter decay and annihilation in the Local Universe. The dark matter distribution is obtained from a constrained cosmological simulation of the neighboring large-scale structure provided by the CLUES project. The dark matter fields of density and density squared are then taken as an input for the Fermi observation simulation tool to predict the gamma-ray photon counts that Fermi would detect in 5 years of all-sky survey for given dark matter models. Signal-to-noise sky maps have also been obtained by adopting the current Galactic and isotropic diffuse background models released by the Fermi collaboration. We point out the possibility for Fermi to detect a dark matter gamma-ray signal in local extragalactic structures. In particular, we conclude here that Fermi observations of nearby clusters (e.g. Virgo and Coma) and filaments are expected to give stronger constraints on decaying dark matter compared to previous studies. As an example, we find a significant signal-to-noise ratio in dark matter models with a decay rate fitting the positron excess as measured by PAMELA. This is the first time that dark matter filaments are shown to be promising targets for indirect detection of dark matter. On the other hand, the prospects for detectability of annihilating dark matter in local extragalactic structures are less optimistic even with extreme cross-sections. We make the dark matter density and density squared maps available online at http://www.clues-project.org/articles/darkmattermaps.html

astro-ph.HE↗

arXiv2009

On possible interpretations of the high energy electron-positron spectrum measured by the Fermi Large Area Telescope

The Fermi-LAT experiment recently reported high precision measurements of the spectrum of cosmic-ray electrons-plus-positrons (CRE) between 20 GeV and 1 TeV. The spectrum shows no prominent spectral features, and is significantly harder than that inferred from several previous experiments. Here we discuss several interpretations of the Fermi results based either on a single large scale Galactic CRE component or by invoking additional electron-positron primary sources, e.g. nearby pulsars or particle Dark Matter annihilation. We show that while the reported Fermi-LAT data alone can be interpreted in terms of a single component scenario, when combined with other complementary experimental results, specifically the CRE spectrum measured by H.E.S.S. and especially the positron fraction reported by PAMELA between 1 and 100 GeV, that class of models fails to provide a consistent interpretation. Rather, we find that several combinations of parameters, involving both the pulsar and dark matter scenarios, allow a consistent description of those results. We also briefly discuss the possibility of discriminating between the pulsar and dark matter interpretations by looking for a possible anisotropy in the CRE flux.

astro-ph.HE↗

arXiv2008

Section on Prospects for Dark Matter Detection of the White Paper on the Status and Future of Ground-Based TeV Gamma-Ray Astronomy

This is a report on the findings of the dark matter science working group for the white paper on the status and future of TeV gamma-ray astronomy. The white paper was commissioned by the American Physical Society, and the full white paper can be found on astro-ph (arXiv:0810.0444). This detailed section discusses the prospects for dark matter detection with future gamma-ray experiments, and the complementarity of gamma-ray measurements with other indirect, direct or accelerator-based searches. We conclude that any comprehensive search for dark matter should include gamma-ray observations, both to identify the dark matter particle (through the charac- teristics of the gamma-ray spectrum) and to measure the distribution of dark matter in galactic halos.

astro-ph↗

arXiv2008

DUSEL Theory White Paper

The NSF has chosen the site for the Deep Underground Science and Engineering Laboratory (DUSEL) to be in Lead, South Dakota. In fact, the state of South Dakota has already stepped up to the plate and contributed its own funding for the proposed lab, see http://www.sanfordlaboratoryathomestake.org/index.html. The final decision by NSF for funding the Initial Suite of Experiments for DUSEL will be made early in 2009. At that time the NSF Science Board must make a decision. Of order 200 experimentalists have already expressed an interest in performing experiments at DUSEL. In order to assess the interest of the theoretical community, the Center for Cosmology and Astro-Particle Physics (CCAPP) at The Ohio State University (OSU) organized a 3-day DUSEL Theory Workshop in Columbus, Ohio from April 4 - 6, 2008. The workshop focused on the scientific case for six proposed experiments for DUSEL: long baseline neutrino oscillations, proton decay, dark matter, astrophysical neutrinos, neutrinoless double beta decay and N-Nbar oscillations. The outcome of this workshop is the DUSEL Theory White paper addressing the scientific case at a level which may be useful in the decision making process for policy makers at the NSF and in the U.S. Congress. In order to assess the physics interest in the DUSEL project we have posted the DUSEL Theory White paper on the following CCAPP link http://ccapp.osu.edu/whitepaper.html . Please read the white paper and, if you are interested, use the link to show your support by co-signing the white paper.

hep-ph↗

arXiv2006

Multi-frequency analysis of neutralino dark matter annihilations in the Coma cluster

We study the astrophysical implications of neutralino dark matter annihilations in galaxy clusters, with a specific application to the Coma cluster. We first address the determination of the dark halo models for Coma, starting from structure formation models and observational data, and we discuss in detail the role of sub-halos. We then perform a thorough analysis of the transport and diffusion properties of neutralino annihilation products, and investigate the resulting multi-frequency signals, from radio to gamma-ray frequencies. We also study other relevant astrophysical effects of neutralino annihilations, like the DM-induced Sunyaev-Zel'dovich effect and the intracluster gas heating. As for the particle physics setup, we adopt a two-fold approach, resorting both to model-independent bottom-up scenarios and to benchmark, GUT-motivated frameworks. We show that the Coma radio-halo data (the spectrum and the surface brightness) can be nicely fitted by the neutralino-induced signal for peculiar particle physics models and for magnetic field values, which we outline in detail. Fitting the radio data and moving to higher frequencies, we find that the multi-frequency spectral energy distributions are typically dim (with respect to the data) at EUV and X-ray frequencies, but show a non-negligible gamma-ray emission, depending on the amplitude of the Coma magnetic field. The best-fit particle physics models also produce a detectable SZ effect, but do not yield substantial heating of the intracluster gas in Coma. Due to the specific multi-frequency features of the DM-induced spectral energy distribution in Coma, we find that supersymmetric models can be significantly and optimally constrained either in the gamma-rays or at radio and microwave frequencies.

astro-ph↗

arXiv2006

Detecting dark matter WIMPs in the Draco dwarf: a multi-wavelength perspective

We explore the possible signatures of dark matter (DM) pair annihilations in the nearby dwarf spheroidal galaxy Draco. After investigating the mass models for Draco in the light of available observational data, we carefully model the DM density profile, taking advantage of numerical simulations of hierarchical structure formation. We then analyze the gamma-ray and electron/positron yield expected for weakly interacting DM particle (WIMP) models, including an accurate treatment of the propagation of the charged particle species. We show that unlike in larger DM structures - such as galaxy clusters - spatial diffusion plays here an important role. While Draco would appear as a point-like gamma-ray source, synchrotron emission from electrons and positrons produced by WIMP annihilations features a spatially extended structure. Depending upon the cosmic ray propagation setup and the size of the magnetic fields, the search for a diffuse radio emission from Draco can be a more sensitive indirect DM search probe than gamma rays. Finally, we show that available data are consistent with the presence of a black hole at the center of Draco: if this is indeed the case, very significant enhancements of the rates for gamma rays and other emissions related to DM annihilations are expected.

astro-ph↗

arXiv2004

Gluino Annihilations and Neutralino Dark Matter

We consider supersymmetric scenarios, compatible with all cosmological and phenomenological requirements, where the lightest SUSY particles (LSPs) are the neutralino and a quasi degenerate gluino. We study the neutralino relic abundance, focusing on gluino (co-)annihilation effects. In case the neutralino is bino-like, in a wide mass window the relic abundance is naturally driven in the correct range for the LSP to be the main cold dark matter constituent. We show that the gluino is the strongest possible coannihilating partner of a bino-like neutralino in the general MSSM. Moreover, contrary to other coannihilation scenarios, gluino pair annihilations always dominate over coannihilation processes, even at relatively large gluino-neutralino mass splittings. Finally, we present prospects for neutralino dark matter detection in the outlined framework.

hep-ph↗

arXiv2004

Lepton Flavor Violation, Neutralino Dark Matter and the Reach of the LHC

We revisit the phenomenology of the Constrained MSSM with right-handed neutrinos (CMSSMRN). A supersymmetric seesaw mechanism, generating neutrino masses and sizable lepton flavour violating (LFV) entries is assumed to be operative. In this scheme, we study the complementarity between the `observable ranges' of various paths leading to the possible discovery of low energy SUSY: the reach of the Cern Large Hadron Collider (LHC), the quest for neutralino dark matter signals and indirect searches through LFV processes. Within the regions of the CMSSMRN parameter space compatible with all cosmo-phenomenological requirements, those which are expected to be probed at the LHC will be typically also accessible to upcoming LFV experiments. Moreover, parameter space portions featuring a heavy SUSY particle spectrum could be well beyond LHC reach while leaving LFV searches as the only key to get a glimpse on SUSY.

hep-ph↗

arXiv2003

Charged Lepton Flavor Violating Decays: Leading Logarithmic Approximation versus Full RG Results

In the context of the minimal supersymmetric extension of the Standard Model with the right-handed Majorana neutrinos, we study lepton flavor violating processes including full renormalization group running effects. We systematically compare our results with the commonly used leading logarithmic approximation, resorting to a ``best fit'' approach to fix all the high energy Yukawa matrices. We find significant deviations in large regions of the SUSY parameter space, which we outline in detail. We also give, within this setting, some results on the cosmo-phenomenologically preferred stau coannihilation region. Finally, we propose a parametrization, in terms of the SUSY input parameters, of the common SUSY mass appearing in the leading log and mass insertion approximation formula for the charged lepton flavor violating decay rates, which fits our full renormalization group results with high precision.

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