Asteroid pairs: A complex picture

Pravec, P.,Fatka, P.,Vokrouhlický,, D.,Scheirich, P.,Ď,urech, J.,Scheeres, D.J.,Ku&#x161,nirá,k, P.,Hornoch, K.,Galá,d, A.,Pray, D.P.,Krugly, Yu. N.,Burkhonov, O.,Ehgamberdiev, Elsevier 2019 Icarus Vol.333 No.-

<P><B>Abstract</B></P> <P>We studied a sample of 93 asteroid pairs, i.e., pairs of genetically related asteroids that are on highly similar heliocentric orbits. We estimated times elapsed since separation of pair members (i.e., pair age) that are between 7 × 10<SUP>3</SUP> yr and a few 10<SUP>6</SUP> yr. With photometric observations, we derived the rotation periods <I>P</I> <SUB>1</SUB> for all the primaries (i.e., the larger members of asteroid pairs) and a sample of secondaries (the smaller pair members). We derived the absolute magnitude differences of the studied asteroid pairs that provide their mass ratios <I>q</I>. For a part of the studied pairs, we refined their WISE geometric albedos and collected or estimated their taxonomic classifications. For 17 asteroid pairs, we also determined their pole positions. In two pairs where we obtained the spin poles for both pair components, we saw the same sense of rotation for both components and constrained the angles between their original spin vectors at the time of their separation. We found that the primaries of 13 asteroid pairs in our sample are actually binary or triple systems, i.e., they have one or two bound, orbiting secondaries (satellites). As a by-product, we found also 3 new young asteroid clusters (each of them consisting of three known asteroids on highly similar heliocentric orbits). We compared the obtained asteroid pair data with theoretical predictions and discussed their implications. We found that 86 of the 93 studied asteroid pairs follow the trend of primary rotation period vs mass ratio that was found by Pravec et al. (2010). Of the 7 outliers, 3 appear insignificant (may be due to our uncertain or incomplete knowledge of the three pairs), but 4 are high mass ratio pairs that were unpredicted by the theory of asteroid pair formation by rotational fission. We discuss a (remotely) possible way that they could be created by rotational fission of flattened parent bodies followed by re-shaping of the formed components. The 13 asteroid pairs with binary primaries are particularly interesting systems that place important constraints on formation and evolution of asteroid pairs. We present two hypotheses for their formation: The asteroid pairs having both bound and unbound secondaries could be “failed asteroid clusters”, or they could be formed by a cascade primary spin fission process. Further studies are needed to reveal which of these two hypotheses for formation of the paired binary systems is real.</P>

Search for τ→eγ decay at Belle

Hayasaka, K.,Abe, K.,Abe, K.,Aihara, H.,Asano, Y.,Aushev, T.,Bahinipati, S.,Bakich, A.M.,Bedny, I.,Bitenc, U.,Bizjak, I.,Blyth, S.,Bondar, A.,Bozek, A.,Brad,ko, M.,Brodzicka, J.,Browder, T.E.,Cha Elsevier 2005 Physics letters: B Vol.613 No.1

<P><B>Abstract</B></P><P>We have searched for the lepton-flavor-violating decay τ→eγ using a data sample of 86.7 fb<SUP>−1</SUP> collected with the Belle detector at the KEKB asymmetric <SUP>e+</SUP><SUP>e−</SUP> collider. No evidence for a signal is obtained, and we set an upper limit for the branching fraction B(τ→eγ)<3.9×<SUP>10−7</SUP> at the 90% C.L.</P>

Search for lepton flavor and lepton number violating <i>τ</i> decays into a lepton and two charged mesons

Miyazaki, Y.,Aihara, H.,Arinstein, K.,Aulchenko, V.,Aushev, T.,Bakich, A.M.,Balagura, V.,Barberio, E.,Bay, A.,Belous, K.,Bhardwaj, V.,Bischofberger, M.,Bondar, A.,Brad,ko, M.,Browder, T.E.,Chang, North-Holland Pub. Co 2010 Physics letters. Section B Vol.682 No.4

<P><B>Abstract</B></P><P>We search for lepton flavor and lepton number violating <I>τ</I> decays into a lepton (ℓ=electron or muon) and two charged mesons (h,<SUP>h′</SUP>=<SUP>π±</SUP> or <SUP>K±</SUP>), <SUP>τ−</SUP>→<SUP>ℓ−</SUP><SUP>h+</SUP><SUP>h′−</SUP> and <SUP>τ−</SUP>→<SUP>ℓ+</SUP><SUP>h−</SUP><SUP>h′−</SUP>, using 671 fb<SUP>−1</SUP> of data collected with the Belle detector at the KEKB asymmetric-energy <SUP>e+</SUP><SUP>e−</SUP> collider. We obtain 90% C.L. upper limits on the branching fractions in the range (4.4–8.8)×<SUP>10−8</SUP> for τ→eh<SUP>h′</SUP>, and (3.3–16)×<SUP>10−8</SUP> for τ→μh<SUP>h′</SUP> processes. These results improve upon previously published upper limits by factors between 1.6 to 8.8.</P>

Search for a dark vector gauge boson decaying toπ+π−usingη→π+π−γdecays

Won, E.,Adachi, I.,Aihara, H.,Al Said, S.,Asner, D. M.,Aushev, T.,Ayad, R.,Badhrees, I.,Bakich, A. M.,Bansal, V.,Barberio, E.,Behera, P.,Bhuyan, B.,Biswal, J.,Bobrov, A.,Bozek, A.,Brad,ko, M.,&#x American Physical Society 2016 Physical Review D Vol.94 No.9

<P>We report a search for a dark vector gauge boson U' that couples to quarks in the decay chain D*(+) -> D-0 pi(+), D-0 -> K-S(0) eta, eta -> U'gamma, U' -> pi(+)pi- No signal is found and we set a mass-dependent limit on the baryonic fine structure constant of 10(-3)-10(-2) in the U' mass range of 290 to 520 MeV/c(2). This analysis is based on a data sample of 976 fb(-1) collected by the Belle experiment at the KEKB asymmetric-energy e(+)e(-) collider.</P>

Measurement of Inclusive RadiativeB-Meson Decays with a Photon Energy Threshold of 1.7 GeV

Limosani, A.,Aihara, H.,Arinstein, K.,Aushev, T.,Bakich, A. M.,Balagura, V.,Barberio, E.,Bay, A.,Belous, K.,Bischofberger, M.,Bondar, A.,Bozek, A.,Brad,ko, M.,Browder, T. E.,Chang, P.,Chao, Y.,Ch American Physical Society 2009 Physical Review Letters Vol.103 No.24

<P>Using 605 fb(-1) of data collected at the Upsilon(4S) resonance we present a measurement of the inclusive radiative B-meson decay channel, B-->X(s)gamma. For the lower photon energy thresholds of 1.7, 1.8, 1.9, and 2.0 GeV, as defined in the rest frame of the B meson, we measure the partial branching fraction and the mean and variance of the photon energy spectrum. At the 1.7 GeV threshold we obtain the partial branching fraction BF(B-->X(s)}gamma)=(3.45+/-0.15+/-0.40)x10(-4), where the errors are statistical and systematic.</P>

Observation ofB0→pp¯K*0with a LargeK*0Polarization

Chen, J.-H.,Wang, M.-Z.,Adachi, I.,Aihara, H.,Arinstein, K.,Aulchenko, V.,Aushev, T.,Bakich, A. M.,Balagura, V.,Barberio, E.,Bay, A.,Bedny, I.,Belous, K.,Bitenc, U.,Bondar, A.,Bozek, A.,Brad,ko, American Physical Society 2008 Physical review letters Vol.100 No.25

<P>Using a 492 fb{-1} data sample collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{+}e{-} collider, we observe the decay B{0}-->ppK*0 with a branching fraction of (1.18{-0.25}{+0.29}(stat)+/-0.11(syst))x10{-6}. We study the decay dynamics of B{0}-->ppK*0 and compare with B{+}-->ppK*+. The K*0 meson is found to be almost 100% polarized (with a fraction of (101+/-13+/-3)% in the helicity zero state), while the K*+ meson has a (32+/-17+/-9)% fraction in the helicity zero state. The direct CP asymmetries for B{0}-->ppK*0 and B{+}-->ppK*+ are measured to be -0.08+/-0.20+/-0.02 and -0.01+/-0.19+/-0.02, respectively. In addition, we report improved measurements of the branching fractions B(B{+}-->ppK*+)=(3.38{-0.60}{+0.73}+/-0.39)x10{-6} and B(B{0}-->ppK{0})=(2.51{-0.29}{+0.35}+/-0.21)x10{-6}, which supersede our previous measurements.</P>

Search forB0→pΛ¯π−γat Belle

Lai, Y.-T.,Wang, M.-Z.,Adachi, I.,Aihara, H.,Asner, D. M.,Aulchenko, V.,Aushev, T.,Bakich, A. M.,Bala, A.,Bhuyan, B.,Bobrov, A.,Bozek, A.,Brad,ko, M.,Browder, T. E.,Chang, P.,Chekelian, V.,Chen, American Physical Society 2014 PHYSICAL REVIEW D - Vol.89 No.5

<P>We search for the charmless B-o decay with final state particles p (Lambda) over bar pi(-)gamma using the full data sample that contains 772 x 10(6)B (B) over bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. This decay is predicted to proceed predominantly via the b -> s gamma radiative penguin process with a high energy photon. No significant signal is found. We set an upper limit of 6.5 x 10(-7) for the branching fraction of B-o -> p (Lambda) over bar pi(-)gamma at the 90% confidence level.</P>

A search for the rare leptonic decays ^B+→^μ+_νμ and ^B+→^e+_νe

Satoyama, N.,Abe, K.,Adachi, I.,Aihara, H.,Anipko, D.,Bakich, A.M.,Barberio, E.,Bedny, I.,Belous, K.,Bitenc, U.,Bizjak, I.,Bondar, A.,Bozek, A.,Brad,ko, M.,Browder, T.E.,Chang, M.-C.,Chang, P.,Ch Elsevier 2007 Physics letters: B Vol.647 No.2

<P><B>Abstract</B></P><P>We present a search for the decays <SUP>B+</SUP>→<SUP>μ+</SUP><SUB>νμ</SUB> and <SUP>B+</SUP>→<SUP>e+</SUP><SUB>νe</SUB> in a 253 fb<SUP>−1</SUP> data sample collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy <I>B</I> factory. We find no significant evidence for a signal and set 90% confidence level upper limits of B(<SUP>B+</SUP>→<SUP>μ+</SUP><SUB>νμ</SUB>)<1.7×<SUP>10−6</SUP> and B(<SUP>B+</SUP>→<SUP>e+</SUP><SUB>νe</SUB>)<9.8×<SUP>10−7</SUP>.</P>

Synthesis and Magnetic Properties of Hematite Particles in a “Nanomedusa” Morphology

Lee, Jin Bae,Kim, Hae Jin,Lu&#x17e,nik, Janez,Jelen, Andreja,Paji&#x107,, Damir,Wencka, Magdalena,Jaglid,i&#x107,, Zvonko,Meden, Anton,Dolin&#x161,ek, Janez Hindawi Limited 2014 Journal of nanomaterials Vol.2014 No.-

<P>We present the synthesis, characterization, and magnetic properties of hematite particles in a peculiar “nanomedusa” morphology. The particles were prepared from an iron-silica complex by a hydrothermal process in a solution consisting of ethyl acetate and ethanol. The particles’ morphology, structure, and chemical composition were investigated by transmission electron microscopy, powder X-ray diffraction, and scanning electron microscope equipped with an energy-dispersive X-ray spectrometer. The “hairy” particles consist of a spherical-like core of about 100 nm diameter and fibrous exterior composed of thin “legs” of 5 nm diameter grown along one preferential direction. The particles’ cores are crystalline and undergo a magnetic phase transition to a weakly ferromagnetic state at a temperature of 930 K that matches reasonably the Néel temperature of bulk hematite. However, unlike bulk hematite that undergoes Morin transition to an antiferromagnetic state around room temperature and small hematite nanoparticles that are superparamagnetic, the “nanomedusa” particles remain weakly ferromagnetic down to the lowest investigated temperature of 2 K. Each particle thus represents a nanodimensional “hairy” ferromagnet in a very broad temperature interval, extending much above the room temperature. Such high-temperature ferromagnetic nanoparticles are not frequently found among the nanomaterials.</P>

Study of Ωc0 and Ωc∗0 baryons at Belle

Solovieva, E.,Chistov, R.,Adachi, I.,Aihara, H.,Arinstein, K.,Aushev, T.,Bakich, A.M.,Balagura, V.,Bitenc, U.,Bondar, A.,Brad,ko, M.,Brodzicka, J.,Browder, T.E.,Chang, P.,Chen, A.,Cheon, B.G.,Cho Elsevier 2009 Physics letters: B Vol.672 No.1

<P><B>Abstract</B></P><P>We report results from a study of the charmed double strange baryons Ωc0 and Ωc∗0 at Belle. The Ωc0 is reconstructed using the Ωc0→<SUP>Ω−</SUP><SUP>π+</SUP> decay mode, and its mass is measured to be (2693.6±0.3−1.5+1.8) MeV/<SUP>c2</SUP>. The Ωc∗0 baryon is reconstructed in the Ωc0γ mode. The mass difference <SUB>MΩc∗0</SUB>−<SUB>MΩc0</SUB> is measured to be (70.7±0.9−0.9+0.1) MeV/<SUP>c2</SUP>. The analysis is performed using 673 fb<SUP>−1</SUP> of data on and near the ϒ(4S) collected with the Belle detector at the KEKB asymmetric-energy <SUP>e+</SUP><SUP>e−</SUP> collider.</P>