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Search for light tetraquark states in ϒ(1S) and ϒ(2S) decays
Jia, S.,Shen, C. P.,Yuan, C. Z.,Adachi, I.,Ahn, J. K.,Aihara, H.,Al Said, S.,Asner, D. M.,Atmacan, H.,Aushev, T.,Ayad, R.,Babu, V.,Badhrees, I.,Bahinipati, S.,Bakich, A. M.,Bansal, V.,Behera, P.,Berge American Physical Society 2017 Physical review. D Vol.96 No.11
<P>We search for the J(PC) = 0(--) and 1(+-) light tetraquark states with masses up to 2.46 GeV/c(2) in gamma(1S) and gamma(2S) decays with data samples of (102 +/- 2) million and (158 +/- 4) million events, respectively, collected with the Belle detector. No significant signals are observed in any of the studied production modes, and 90% credibility level (C. L.) upper limits on their branching fractions in Upsilon(1S) and Upsilon(2S) decays are obtained. The inclusive branching fractions of the Upsilon(1S) and Upsilon(2S) decays into final states with f(1)(1285) are measured to be B(Upsilon(1S) -> f(1)(1285) + anything) = (46 +/- 28(stat) +/- 13(syst)) x 10(-4) and B(Upsilon(2S) -> f(1)(1285) + anything) = (22 +/- 15(stat) +/- 6.3(syst)) x 10(-4). The measured chi(b2) -> J/Psi + anything branching fraction is measured to be (1.50 +/- 0.34(stat) +/- 0.22(syst)) x 10(-3), and 90% C. L. upper limits for the chi(b0;b1) -> J/Psi + anything branching fractions are found to be 2.3 x 10(-3) and 1.1 x 10(-3), respectively. For B(chi(b1) -> omega + anything), the branching fraction is measured to be (4.9 +/- 1.3(stat) +/- 0.6(syst) x 10(-2). All results reported here are the first measurements for these modes.</P>
Babu, P.,Jang, K.H.,Kim, E.S.,Vijaya, R.,Jayasankar, C.K.,Lavin, V.,Seo, H.J. North-Holland 2011 Journal of non-crystalline solids Vol.357 No.10
A fluorometaphosphate laser glass doped with Eu<SUP>3+</SUP> ions has been synthesized and studied by broad band optical spectroscopy and time-resolved fluorescence line narrowing techniques in order to explore the local field dependent fluorescence properties of the lanthanide ions in this host. From the Raman and the vibronic spectra, various structural phosphate groups coupled to the Eu<SUP>3+</SUP> ions have been identified. Local field dependent <SUP>5</SUP>D<SUB>0</SUB>→<SUP>7</SUP>F<SUB>J</SUB> (J=0-6) emission spectra and the lifetimes of the <SUP>5</SUP>D<SUB>0</SUB> level have been measured under resonant excitation of the Eu<SUP>3+</SUP> ions at different wavelengths within the <SUP>7</SUP>F<SUB>0</SUB>→<SUP>5</SUP>D<SUB>0</SUB> band at 16K. From these data and using the Stark level positions of the <SUP>7</SUP>F<SUB>1</SUB> and <SUP>7</SUP>F<SUB>2</SUB> multiplets, a crystal-field analysis has been carried out assuming a C<SUB>2v</SUB> orthorhombic local symmetry. The radiative Judd-Ofelt parameters have been calculated for the different local fields found in the glass and their relative variation has been discussed. The results obtained suggest the existence of a relatively narrow distribution of local fields generated by successive distortions of a unique kind of site for all the Eu<SUP>3+</SUP> ions in this fluorometaphosphate glass.
Study of B0→ρ+ρ−decays and implications for the CKM angleϕ2
Vanhoefer, P.,Dalseno, J.,Kiesling, C.,Abdesselam, A.,Adachi, I.,Aihara, H.,Al Said, S.,Arinstein, K.,Asner, D. M.,Atmacan, H.,Aushev, T.,Aziz, T.,Babu, V.,Badhrees, I.,Bakich, A. M.,Bansal, V.,Barber American Physical Society 2016 Physical Review D Vol.93 No.3
<P>We present a measurement of the branching fraction and the longitudinal polarization fraction of B-0 -> rho(+)rho(-) decays, as well as the time-dependent CP violating parameters in decays into longitudinally polarized rho(+)rho(-) pairs with Belle's final data set of 772 x 10(6) B (B) over bar pairs, at the Upsilon(4S) resonance, collected at the asymmetric-energy e(+)e(-) collider KEKB. We obtain B(B-0 -> rho(+)rho(-)) = (28.3 +/- 1.5(stat) +/- 1.5(syst)) x 10(-6), f(L) = 0.988 +/- 0.012(stat) +/- 0.023(syst), A(CP) = 0.00 +/- 0.10(stat) +/- 0.06(syst), S-CP = -0.13 +/- 0.15(stat) +/- 0.05(syst). We perform an isospin analysis to constrain the Cabibbo-Kobayashi-Maskawa angle phi(2) and obtain two solutions with phi(2) = (93.7 +/- 10.6)degrees, being most compatible with other Standard-Model based fits to the data.</P>
Observation of an alternative χc0(2P) candidate in e+e−→J/ψDD¯
Chilikin, K.,Adachi, I.,Aihara, H.,Al Said, S.,Asner, D. M.,Aulchenko, V.,Ayad, R.,Babu, V.,Badhrees, I.,Bakich, A. M.,Bansal, V.,Barberio, E.,Besson, D.,Bhardwaj, V.,Bhuyan, B.,Biswal, J.,Bobrov, A. American Physical Society 2017 Physical Review D Vol.95 No.11
<P>We perform a full amplitude analysis of the process e(+)e(-)-> J/psi D (D) over bar, where D refers to either D-0 or D+. A new charmoniumlike state X*(3860) that decays to D (D) over bar is observed with a significance of 6.5 sigma. Its mass is (3862(-32)(+26) (+40)(-13) )MeV= c(2), and its width is (201(-67) (+154)(-82) (+88)) MeV. The J(PC) = 0(++) hypothesis is favored over the 2(++) hypothesis at the level of 2.5s. The analysis is based on the 980 fb(-1) data sample collected by the Belle detector at the asymmetric-energy e(+)e(-)collider KEKB.</P>
Search for the 0−− glueball in ϒ(1S) and ϒ(2S) decays
Jia, S.,Shen, C. P.,Yuan, C. Z.,Adachi, I.,Aihara, H.,Al Said, S.,Asner, D. M.,Aushev, T.,Ayad, R.,Babu, V.,Badhrees, I.,Bakich, A. M.,Bansal, V.,Barberio, E.,Behera, P.,Bhuyan, B.,Biswal, J.,Bonvicin American Physical Society 2017 Physical Review D Vol.95 No.1
<P>We report the first search for the J(PC) = 0(--) glueball in Upsilon(1S) and Upsilon(2S) decays with data samples of (102 +/- 2) x 10(6) and (158 +/- 4) x 10(6) events, respectively, collected with the Belle detector. No significant signals are observed in any of the proposed production modes, and the 90% credibility level upper limits on their branching fractions in Upsilon(1S) and Upsilon(2S) decays are obtained. The inclusive branching fractions of the Upsilon(1S) and Upsilon(2S) decays into final states with chi(c1) are measured to be B(Upsilon(1S) -> chi(c1) + anything) = (1.90 +/- 0.43(stat) +/- 0.14(syst) x 10(-4) with an improved precision over prior measurements and B Upsilon(2S) -> chi(c1) + anything) = (2.24 +/- 0.44(stat) +/- 0.20(syst) x 10(-4) for the first time.</P>
Dry sliding wear behavior of aluminum based hybrid composites with graphite nanofiber-alumina fiber
Babu, J.S.S.,Kang, C.G.,Kim, H.H. Scientific and Technical Press ; Elsevier Science 2011 MATERIALS AND DESIGN Vol.32 No.7
The wear behavior of aluminum based hybrid composites reinforced with graphite nanofiber (GNF) and alumina short fiber (Al<SUB>2</SUB>O<SUB>3sf</SUB>) in different volume fraction of fibers (10%, 15% and 20%) was studied under dry sliding conditions. The Taguchi approach to experimental design was used to identify those testing parameters that have the largest effects on wear loss and coefficient of friction of the composites. Sliding distance was found to be the prominent parameter affecting wear loss; applied load affected coefficient of friction most significantly. The results of Taguchi analysis indicate that wear loss increases with increasing load and sliding distance, but it is reduced with increasing sliding speed. Coefficient of friction decreases with increasing applied load and sliding speed whereas it increases with increasing sliding distance. The composites with 10vol.% and 15vol.% of fiber had the lowest wear loss and friction because of the mixture effect of GNFs and Al<SUB>2</SUB>O<SUB>3sf</SUB>. However, due to the effect of agglomerated GNFs, there was an increase in wear loss and friction at 20vol.%.
Babu, R.,Kim, S.H.,Kathalikkattil, A.C.,Kuruppathparambil, R.R.,Kim, D.W.,Cho, S.J.,Park, D.W. Elsevier 2017 Applied Catalysis A Vol.544 No.-
A multilinker non-interpenetrated metal-organic framework, UMCM-15, was synthesized by using microwave power as an alternative energy-efficient tool for the first time. The synergistic catalytic activity, when combined with a co-catalyst containing a strongly nucleophilic anion, was studied in the solventless room temperature cycloaddition between epoxides and CO<SUB>2</SUB>. Unlike previous reports on UMCM-15 synthesized in the high-boiling solvent dimethylformamide, low boiling water/ethanol mixture was used as the solvent herein. This approach holds potential as a sustainable green methodology. Crystal formation during the microwave-assisted (MW) synthesis was monitored at certain time intervals. The favorable role of non-interpenetrated pillared structures in promoting room temperature CO<SUB>2</SUB>-epoxide cycloaddition reactions was explained by comparing the catalytic efficiency of the three-linker extended pillar-layered non-interpenetrated UMCM-15 with its analogous pillared structures built from two- and three-fold interpenetrated ([Zn<SUB>2</SUB>(BDC)<SUB>2</SUB>(4,4'-bipy)] and [Zn<SUB>2</SUB>(NDC)<SUB>2</SUB>(4,4'-bipy)]) catalytic systems with a single dicarboxylate linker. The efficacy of the microwave-assisted UMCM-15(M) catalyst in cycloaddition reactions was proved by comparing the catalytic activity of UMCM-15(M) with that of the congener made by solvothermal synthesis, UMCM-15(S). In addition, a plausible mechanism for the synergistic operation of the Lewis acid sites and nucleophiles was suggested.
J. S. S. Babu,A. Srinivasan,Chung Gil Kang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9
In this article, the tribological properties of aluminum/MWCNTs/Al2O3sf hybrid composites with varying volume fractionof 10 vol%, 15 vol% and 20 vol% was investigated under dry sliding conditions. The experiments were performed accordingto design of experiments approach using Taguchi method to predict the wear properties of composites. The results indicatedthat the composites of 15 vol% had lower wear loss, whereas the coefficient of friction (COF) decreased significantly at 20vol%. Taguchi based ANOVA analysis showed that the sliding distance was found to be the prominent factor controllingthe wear loss; applied load influenced COF most significantly. It could also be noticed that the COF and wear loss increaseswith an increase in sliding load and sliding distance. The decrease in wear loss and the COF can be attributed to the selflubricationeffect of MWCNTs, and the combined effect of reinforcements in the composites. In addition, nanoscratch testwas performed to determine the COF and the effect of the reinforcements on local regions of the composites. The resultsrevealed that higher friction force was obtained near the regions of MWCNTs and Al2O3sfwhile nanoscratching. The COFof composites of 20 vol% was found to slightly higher compared to that of 10 vol% and 15 vol%. This is attributed to thepresence of MWCNTs cluster within the Al2O3sfnetwork results prevent the micro-plastic deformation of Al matrix, and theformation of tribofilms with nanoscaled thickness in the scratch region. These friction and wear results indicate that the presenceof a limited amount and size of MWCNTs clusters are beneficial to the tribological properties of the hybrid composites.