scholarly journals NA62 and NA48/2 results on search for Heavy Neutral Leptons

2018 ◽  
Vol 179 ◽  
pp. 01009
Author(s):  
Gianluca Lamanna ◽  
R. Aliberti ◽  
F. Ambrosino ◽  
R. Ammendola ◽  
B. Angelucci ◽  
...  
Keyword(s):  
Mass Range ◽  
Kaon Mass ◽  
Upper Limits ◽  
The Status

In this paper we present new results on upper limits for the search of Heavy Neutral Leptons (HNL) with data collected by NA48/2 (2003-2004), NA62-RK (2007) and NA62 (2015) CERN experiments. The data collected with different trigger configuration allow to search for both long and short living heavy neutrinos in the mass range below the kaon mass. In addition the status of the search for K+ → π+vv with the NA62 detector will be briefly presented.

scholarly journals Quantifying tidal stream disruption in a simulated Milky Way

2017 ◽  
Vol 470 (1) ◽  
pp. 522-538 ◽  
Author(s):  
Emily Sandford ◽  
Andreas H. W. Küpper ◽  
Kathryn V. Johnston ◽  
Jürg Diemand
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Galactic Halo ◽  
Mass Range ◽  
Galactic Centre ◽  
High Dimensions ◽  
Density Profiles ◽  
Upper Limits ◽  
Tidal Stream ◽  
Tidal Streams

Abstract Simulations of tidal streams show that close encounters with dark matter subhaloes induce density gaps and distortions in on-sky path along the streams. Accordingly, observing disrupted streams in the Galactic halo would substantiate the hypothesis that dark matter substructure exists there, while in contrast, observing collimated streams with smoothly varying density profiles would place strong upper limits on the number density and mass spectrum of subhaloes. Here, we examine several measures of stellar stream ‘disruption' and their power to distinguish between halo potentials with and without substructure and with different global shapes. We create and evolve a population of 1280 streams on a range of orbits in the Via Lactea II simulation of a Milky Way-like halo, replete with a full mass range of Λcold dark matter subhaloes, and compare it to two control stream populations evolved in smooth spherical and smooth triaxial potentials, respectively. We find that the number of gaps observed in a stellar stream is a poor indicator of the halo potential, but that (i) the thinness of the stream on-sky, (ii) the symmetry of the leading and trailing tails and (iii) the deviation of the tails from a low-order polynomial path on-sky (‘path regularity') distinguish between the three potentials more effectively. We furthermore find that globular cluster streams on low-eccentricity orbits far from the galactic centre (apocentric radius ∼30–80 kpc) are most powerful in distinguishing between the three potentials. If they exist, such streams will shortly be discoverable and mapped in high dimensions with near-future photometric and spectroscopic surveys.

scholarly journals Search for heavy neutral leptons in $$W^+\rightarrow \mu ^{+}\mu ^{\pm }\, \text {jet}$$ decays

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Mass Range ◽  
Lepton Number ◽  
Heavy Neutrino ◽  
Proton Collision ◽  
Final State ◽  
Data Set ◽  
Proton Proton ◽  
Upper Limits ◽  
The Standard Model ◽  
Proton Proton Collision

AbstractA search is performed for heavy neutrinos in the decay of a W boson into two muons and a jet. The data set corresponds to an integrated luminosity of approximately $$3.0\, \text {fb} ^{-1} $$ 3.0 fb - 1 of proton–proton collision data at centre-of-mass energies of 7 and $$8\, \text {TeV} $$ 8 TeV collected with the LHCb experiment. Both same-sign and opposite-sign muons in the final state are considered. Data are found to be consistent with the expected background. Upper limits on the coupling of a heavy neutrino with the Standard Model neutrino are set at $$95\%$$ 95 % confidence level in the heavy-neutrino mass range from 5 to $$50\, \text {GeV/}c^2 $$ 50 GeV/ c 2 . These are of the order of $$10^{-3}$$ 10 - 3 for lepton-number-conserving decays and of the order of $$10^{-4}$$ 10 - 4 for lepton-number-violating heavy-neutrino decays.

scholarly journals Search for the doubly charmed baryon $$\Xi_{cc}^+$$

2019 ◽  
Vol 63 (2) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Production Cross ◽  
Branching Fraction ◽  
Mass Range ◽  
Proton Collision ◽  
Final State ◽  
Momentum Range ◽  
Proton Proton ◽  
Charmed Baryon ◽  
Upper Limits ◽  
Lhcb Detector

AbstractA search for the doubly charmed baryon $$\Xi_{cc}^+$$Ξcc+ is performed through its decay to the $$\Lambda_c^ + {K^ -}{\pi ^ +}$$Λc+K−π+ final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data correspond to a total integrated luminosity of 9 fb−1. No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c2. Upper limits are set at 95% credibility level on the ratio of the $$\Xi_{cc}^+$$Ξcc+ production cross-section times the branching fraction to that of $$\Lambda_c^ + $$Λc+ and $$\Xi_{cc}^{+ +}$$Ξcc++ baryons. The limits are determined as functions of the $$\Xi_{cc}^+$$Ξcc+ mass for different lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.

scholarly journals Upper limits on resonance contributions to proton-proton elastic scattering in the c.m. mass range 2.05-2.85 GeV/ c2

2006 ◽  
Vol 28 (1) ◽  
pp. 115-124
Author(s):  
H. Rohdjeß ◽  
M. Altmeier ◽  
F. Bauer ◽  
J. Bisplinghoff ◽  
R. Bollmann ◽  
...  
Keyword(s):  
Elastic Scattering ◽  
Mass Range ◽  
Proton Proton ◽  
Proton Elastic Scattering ◽  
Upper Limits

scholarly journals Search for a heavy Higgs boson decaying into a Z boson and another heavy Higgs boson in the $$\ell \ell bb$$ and $$\ell \ell WW$$ final states in pp collisions at $$\sqrt{s}=13$$ $$\text {TeV}$$ with the ATLAS detector

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Mass Range ◽  
Higgs Doublet ◽  
Atlas Detector ◽  
Final States ◽  
Proton Proton ◽  
Upper Limits ◽  
Higgs Boson Decaying ◽  
Proton Proton Collisions ◽  
Heavy Higgs Boson

AbstractA search for a heavy neutral Higgs boson, A, decaying into a Z boson and another heavy Higgs boson, H, is performed using a data sample corresponding to an integrated luminosity of 139 fb$$^{-1}$$ - 1 from proton–proton collisions at $$\sqrt{s} = 13$$ s = 13  $$\text {TeV}$$ TeV recorded by the ATLAS detector at the LHC. The search considers the Z boson decaying into electrons or muons and the H boson into a pair of b-quarks or W bosons. The mass range considered is 230–800 $$\text {GeV}$$ GeV for the A boson and 130–700 $$\text {GeV}$$ GeV for the H boson. The data are in good agreement with the background predicted by the Standard Model, and therefore 95% confidence-level upper limits for $$\sigma \times B(A\rightarrow ZH)\times B(H\rightarrow bb \; \text {or} \; H \rightarrow WW)$$ σ × B ( A → Z H ) × B ( H → b b or H → W W ) are set. The upper limits are in the range 0.0062–0.380 pb for the $$H\rightarrow bb$$ H → b b channel and in the range 0.023–8.9 pb for the $$H\rightarrow WW$$ H → W W channel. An interpretation of the results in the context of two-Higgs-doublet models is also given.

scholarly journals Search for the doubly charmed baryon Ω+cc

2021 ◽  
Vol 64 (10) ◽  
Author(s):  
◽  
R. Aaij ◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Production Cross ◽  
Branching Fraction ◽  
Mass Range ◽  
Proton Collision ◽  
Centre Of Mass ◽  
Momentum Range ◽  
Proton Proton ◽  
Charmed Baryon ◽  
Upper Limits ◽  
Proton Proton Collision

AbstractA search for the doubly charmed baryon Ω cc + with the decay mode Ω cc + → Ξ c + K−π+ is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of 5.4 fb−1. No significant signal is observed within the invariant mass range of 3.6 to 4.0GeV/c2. Upper limits are set on the ratio R of the production cross-section times the total branching fraction of the Ω cc + → Ξ c + K−π+ decay with respect to the $$\Xi _{cc}^{ + + } \to \Lambda _c^ + {K^ - }{\pi ^ + }{\pi ^ + }$$ Ξ c c + + → Λ c + K − π + π + decay. Upper limits at 95% credibility level for R in the range 0.005 to 0.11 are obtained for different hypotheses on the Ω cc + mass and lifetime in the rapidity range from 2.0 to 4.5 and transverse momentum range from 4 to 15 GeV/c.

scholarly journals xGASS: passive discs do not host unexpectedly large reservoirs of cold atomic hydrogen

2020 ◽  
Vol 494 (1) ◽  
pp. L42-L47 ◽  
Author(s):  
L Cortese ◽  
B Catinella ◽  
R H W Cook ◽  
S Janowiecki
Keyword(s):  
Star Formation ◽  
Atomic Hydrogen ◽  
Main Sequence ◽  
Formation Rate ◽  
Large Population ◽  
Mass Range ◽  
Star Forming ◽  
Central Disc ◽  
Upper Limits ◽  
Disc Galaxies

ABSTRACT We use the extended GALEX Arecibo SDSS Survey (xGASS) to quantify the relationship between atomic hydrogen (H i) reservoir and current star formation rate (SFR) for central disc galaxies. This is primarily motivated by recent claims for the existence, in this sample, of a large population of passive discs harbouring H i reservoirs as large as those observed in main-sequence galaxies. Across the stellar mass range 109 < M*/M⊙ < 1011, we practically find no passive (≳2σ below the star forming main sequence) disc galaxies with H i reservoirs comparable to those typical of star-forming systems. Even including H i non-detections at their upper limits, passive discs typically have ≥0.5 dex less H i than their active counterparts. We show that previous claims are due to the use of aperture-corrected SFR estimates from the MPA/JHU SDSS DR7 catalogue, which do not provide a fair representation of the global SFR of H i-rich galaxies with extended star-forming discs. Our findings confirm that the bulk of the passive disc population in the local Universe is H i-poor. These also imply that the reduction of star formation, even in central disc galaxies, has to be accompanied by a reduction in their H i reservoir.

scholarly journals Search for the dark photon in B0 → A′A′, A′ → e+e−, μ+μ−, and π+π− decays at Belle

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
S.-H. Park ◽  
◽  
Y.-J. Kwon ◽  
I. Adachi ◽  
H. Aihara ◽  
...  
Keyword(s):  
Higgs Mass ◽  
Branching Fraction ◽  
Branching Fractions ◽  
Charged Particles ◽  
Mass Range ◽  
Photon Mass ◽  
Dark Photon ◽  
Belle Detector ◽  
Upper Limits ◽  
Higgs Portal

Abstract We present a search for the dark photon A′ in the B0 → A′A′ decays, where A′ subsequently decays to e+e−, μ+μ−, and π+π−. The search is performed by analyzing 772 × 106$$ B\overline{B} $$ B B ¯ events collected by the Belle detector at the KEKB e+e− energy-asymmetric collider at the ϒ(4S) resonance. No signal is found in the dark photon mass range 0.01 GeV/c2 ≤ mA′ ≤ 2.62 GeV/c2, and we set upper limits of the branching fraction of B0 → A′A′ at the 90% confidence level. The products of branching fractions, $$ \mathrm{\mathcal{B}}\left({B}^0\to A^{\prime }A^{\prime}\right)\times \mathrm{\mathcal{B}}{\left(A\prime \to {e}^{+}{e}^{-}\right)}^2 $$ ℬ B 0 → A ′ A ′ × ℬ A ′ → e + e − 2 and $$ \mathrm{\mathcal{B}}\left({B}^0\to A^{\prime }A^{\prime}\right)\times \mathrm{\mathcal{B}}{\left(A\prime \to {\mu}^{+}{\mu}^{-}\right)}^2 $$ ℬ B 0 → A ′ A ′ × ℬ A ′ → μ + μ − 2 , have limits of the order of 10−8 depending on the A′ mass. Furthermore, considering A′ decay rate to each pair of charged particles, the upper limits of $$ \mathrm{\mathcal{B}}\left({B}^0\to A^{\prime }A^{\prime}\right) $$ ℬ B 0 → A ′ A ′ are of the order of 10−8–10−5. From the upper limits of $$ \mathrm{\mathcal{B}}\left({B}^0\to A^{\prime }A^{\prime}\right) $$ ℬ B 0 → A ′ A ′ , we obtain the Higgs portal coupling for each assumed dark photon and dark Higgs mass. The Higgs portal couplings are of the order of 10−2–10−1 at $$ {m}_{h\prime}\simeq {m}_{B^0} $$ m h ′ ≃ m B 0 ± 40 MeV/c2 and 10−1–1 at $$ {m}_{h\prime}\simeq {m}_{B^0} $$ m h ′ ≃ m B 0 ± 3 GeV/c2.

CONSTRAINING DARK MATTER ANNIHILATION WITH NEUTRINOS AND GAMMA RAYS

2011 ◽  
Vol 01 ◽  
pp. 245-251
Author(s):  
NICOLE F. BELL
Keyword(s):  
Dark Matter ◽  
Total Cross Section ◽  
Cross Section ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Mass Range ◽  
Dark Matter Halo ◽  
Dark Matter Annihilation ◽  
Upper Limits ◽  
Wide Range

We examine dark matter annihilation in galaxy halos. By considering annihilation into all Standard Model particles we show that the least detectable final states, namely neutrinos, define a strong general upper bound on the total cross section. This limit is much stronger than the unitarity bound in the most interesting mass range and implies annihilation cannot significantly modify dark matter halo density profiles. We also calculate conservative upper limits on the self-annihilation cross section to monoenergetic gamma rays over a wide range of dark matter masses, using gamma-ray data from the Milky Way, Andromeda (M31), and the cosmic background. We compare gamma-ray-based and neutrino-based upper limits on the total cross section.

scholarly journals Exploring the Limits to Observational Diffuse Interstellar Band Studies

2013 ◽  
Vol 9 (S297) ◽  
pp. 51-57
Author(s):  
B. H. Foing
Keyword(s):  
Observational Studies ◽  
Organic Molecules ◽  
Microwave Emission ◽  
Large Molecules ◽  
Near Ir ◽  
Upper Limits ◽  
The Status ◽  
Extended Red Emission ◽  
Photo Stability ◽  
Galactic Sources

AbstractThe status of DIB research (Herbig 1995) has strongly advanced since the DIB conference in Boulder in 1994. In the same year we reported the discovery of two near IR diffuse bands coincident with C60+, that was confirmed in subsequent years. Since then a number of DIB observational studies have been published such as DIB surveys, measurements of DIB families, correlations and environment dependences as well as DIBs in extra-galactic sources. Resolved substructures were measured and compared to predicted rotational contours of large molecules. Polarisation studies provided constraints on possible carrier molecules and upper limits. DIBs carriers have been linked with several classes of organic molecules observed in the interstellar medium, in particular to the UIR bands (assigned to PAHs), the Extended Red Emission (ERE) or the recently detected Anomalous Microwave Emission (AME, assigned to spinning dust). In particular fullerenes and PAHs have been proposed to explain some DIBs and specific molecules were searched for in DIB spectra. DIB carriers could be present in various dehydrogenation and ionization states. Experiments in the laboratory and in space contribute to our understanding of the photo-stability of possible DIB carriers. In summary, the status of DIB research in the last 20 years has strongly advanced. We review DIB observational results and their interpretation and introduce the relevant plenary discussion.

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