265 research outputs found

    Semileptonic Bq→Dq∗lνB_{q}\to D^{\ast}_{q}l\nu (q=s,d,u)(q=s, d, u) transitions in QCD

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    The form factors relevant to Bq→Dq∗(JP=1−)ℓνB_{q}\to D^{\ast}_{q}(J^{P}=1^{-})\ell\nu (q=s,d,u)(q=s, d, u) decays are calculated in the framework of the three point QCD sum rules approach. The heavy quark effective theory prediction of the form factors are obtained. The total decay width and branching ratio for these decays are also evaluated using the q2q^2 dependencies of these form factors.Comment: 4 pages, 4 figures and 3 tables. To be published in the proceedings of the 14th International QCD Conference (QCD 08), Montpellier, France, 7-12 July 200

    Double-Lepton Polarization Asymmetries and Polarized Forward Backward Asymmetries in the Rare b \to s \ell^+ \ell^- Decays in a Single Universal Extra Dimension Scenario

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    We study the double-lepton polarization asymmetries and single and double-lepton polarization forward backward asymmetries of the rare b \to s \ell^+ \ell^- mode within the Standard Model and in the Appelquist-Cheng-Dobrescu model, which is a new physics scenario with a single universal extra dimension. In particular, we examine the sensitivity of the observables to the radius R of the compactified extra-dimension, which is the new parameter in this new physics model.Comment: 20 Pages, 15 Figures and 1 Tabl

    Semileptonic Bq→Dq∗lνB_{q}\to D^{\ast}_{q}l\nu (q=s,d,u)(q=s, d, u) Decays in QCD Sum Rules

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    The form factors relevant to Bq→Dq∗(JP=1−)ellνB_{q}\to D^{\ast}_{q}(J^{P}=1^{-}) ell\nu (q=s,d,u)(q=s, d, u) decays are calculated in the framework of the three point QCD sum rules approach. The heavy quark effective theory prediction of the form factors as well as 1/mb1/m_{b} corrections to those form factors are obtained. A comparison of the results for the ratio of form factors at zero recoil limit and other values of q2q^{2} with the predictions of the subleading Isgur-Wise form factor application for B→D∗ℓνB\to D^{\ast}\ell\nu is presented. The total decay width and branching ratio for these decays are also evaluated using the q2q^2 dependencies of these form factors. The results are in good agreement with the constituent quark meson model and existing experimental data. The q=sq=s case can also be detected at LHC in the near future.Comment: 28 Pages, 6 Figures and 9 Table

    Flavor Changing Neutral Currents Transition of the ΣQ\Sigma_{Q} to Nucleon in Full QCD and Heavy Quark Effective Theory

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    The loop level flavor changing neutral currents transitions of the Σb→nl+l−\Sigma_{b}\to n l^+l^- and Σc→pl+l−\Sigma_{c}\to p l^+l^- are investigated in full QCD and heavy quark effective theory in the light cone QCD sum rules approach. Using the most general form of the interpolating current for ΣQ\Sigma_{Q}, Q=bQ=b or cc, as members of the recently discovered sextet heavy baryons with spin 1/2 and containing one heavy quark, the transition form factors are calculated using two sets of input parameters entering the nucleon distribution amplitudes, namely, QCD sum rules and lattice QCD inputs. The obtained results are used to estimate the decay rates of the corresponding transitions. Since such type transitions occurred at loop level in the standard model, they can be considered as good candidates to search for the new physics effects beyond the SM.Comment: 18 Pages and 13 Table

    Performance Evaluation of Homogeneous Charge Compression Ignition Combustion Engine â A Review

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    The development of HCCI combustion technology has been drawing a great deal of attention from researchers. This survey explains ongoing research methodologies and results. HCCI combustion, other than conventional combustion, is purely based on chemical kinetics. At present the automobile sector faces the problem of emissions and needs to develop clean technologies. However, HCCI operation still has issues such as ignition control, combustion phasing control, operating range control, cold start, and UHC (unburned hydrocarbon) and CO (carbon monoxide) emissions. The challenge is to overcome these problems without compromising other engine parameters and performance. For HCCI, the mixture preparation is especially important, while the compression ratio, IVC (inlet valve closure) timing, inlet pressure, inlet temperature and EGR play a very prominent role in controlling it. This paper will go through a detailed discussion of all the above conditions

    g_phi-pion-gamma coupling constant in light cone QCD sum rules

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    The coupling constant of g_phi-pion-gamma decay is calculated using light cone QCD sum rules. A comparison of our result with the ones existing in the literature is presented.Comment: 9 pages, 2 figure

    Scalar Quarkonia at Finite Temperature

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    Masses and decay constants of the scalar quarkonia, χQ0(Q=b,c)\chi_{Q0} (Q=b,c) with quantum numbers IG(JPC)=0+(0++)I^G(J^{PC})=0^{+}(0^{++}) are calculated in the framework of the QCD sum rules approach both in vacuum and finite temperature. The masses and decay constants remain unchanged up to T≃100 MeVT\simeq100~MeV but they start to diminish with increasing the temperature after this point. At near the critic or deconfinement temperature, the decay constants reach approximately to 25% of their values in vacuum, while the masses are decreased about 6% and 23% for bottom and charm cases, respectively. The results at zero temperature are in a good consistency with the existing experimental values and predictions of the other nonperturbative approaches. Our predictions on the decay constants in vacuum as well as the behavior of the masses and decay constants with respect to the temperature can be checked in the future experiments.Comment: 12 Pages, 9 Figures and 2 Table

    Physiological responses of cultured bovine granulosa cells to elevated temperatures under low and high oxygen in the presence of different concentrations of melatonin

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    Our understanding of the effects of temperature on granulosa cell (GC) physiology is primarily limited to in vitro studies conducted under atmospheric (approx 20% O2) conditions. In the current series of factorial experiments we identify important effects of O2 level (i.e. 5% vs 20% O2) on GC viability and steroidogenesis, and go onto report effects of standard (37.5°C) vs high (40.0°C) temperatures under more physiologically representative (i.e. 5%) O2 levels in the presence of different levels of melatonin (0, 20, 200 and 2000 pg/mL); a potent free-radical scavenger and abundant molecule within the ovarian follicle. Cells aspirated from antral (4 to 6 mm) follicles were cultured in fibronectin-coated wells using serum-free M199 for up to 144 h. At 37.5 C viable cell number was enhanced and luteinization reduced under 5 vs 20% O2. Oxygen level interacted (P<0.001) with time in culture to affect aromatase activity and cell estradiol (E2) production (pg/mL/105 cells). These decreased between 48 and 96 h for both O2 levels but increased again by 144 h for cells cultured under 5% but not 20% O2. Progesterone (P4) concentration (ng/mL/105 cells) was greater (P<0.001) under 20 vs 5% O2 at 96 and 144 h. Cell number increased (P<0.01) with time in culture under 5% O2 irrespective of temperature. However, higher doses of melatonin increased viable cell number at 40.0°C but reduced viable cell number at 37.5°C (P=0.004). Melatonin also reduced (P<0.001) ROS generation at both O2 levels across all concentrations. E2 increased with time in culture at both temperatures under 5% O2, however P4 declined between 96 to 144 h at 40.0 but not 37.5°C. Furthermore, melatonin interacted (P<0.001) with temperature in a dose dependent manner to increase P4 at 37.5°C but to reduce P4 at 40.0°C. Transcript expression for HSD3B1 paralleled temporal changes in P4 production, and those for HBA were greater at 5% than 20% O2, suggesting that hemoglobin synthesis is responsive to changes in O2 level. In conclusion, 5% O2 enhances GC proliferation and reduces luteinization. Elevated temperatures under 5% O2 reduce GC proliferation and P4 production. Melatonin reduces ROS generation irrespective of O2 level and temperature, but interacts with temperature in a dose dependent manner to influence GC proliferation and luteinization

    Asymmetry Parameter of the K1(1270,1400)K_{1} (1270, 1400) by Analyzing the B→K1ννˉB\to K_{1}\nu \bar{\nu} Transition Form Factors within QCD

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    Separating the mixture of the K1(1270) K_{1}(1270) and K1(1400)K_{1}(1400) states, the B→K1(1270,1400)ννˉB\to K_{1}(1270, 1400)\nu\bar{\nu} transition form factors are calculated in the three-point QCD sum rules approach. The longitudinal, transverse and total decay widths as well as the asymmetry parameter, characterizing the polarization of the axial K1(1270,1400)K_{1}(1270, 1400) and the branching ratio for these decays are evaluated.Comment: 25 pages, 3 figures, 3 table

    Weak decays of heavy hadrons into dynamically generated resonances

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    In this paper, we present a review of recent works on weak decay of heavy mesons and baryons with two mesons, or a meson and a baryon, interacting strongly in the final state. The aim is to learn about the interaction of hadrons and how some particular resonances are produced in the reactions. It is shown that these reactions have peculiar features and act as filters for some quantum numbers which allow to identify easily some resonances and learn about their nature. The combination of basic elements of the weak interaction with the framework of the chiral unitary approach allow for an interpretation of results of many reactions and add a novel information to different aspects of the hadron interaction and the properties of dynamically generated resonances.We would like to thank C. Hanhart and S. Stone for valuable comments on the manuscript. One of us, E. O., wishes to acknowledge support from the Chinese Academy of Science in the Program of Visiting Professorship for Senior International Scientists (Grant No. 2013T2J0012). This work is partly supported by the Spanish Ministerio de Economia y Competitividad and European FEDER funds under the contract numbers FIS2011-28853-C02-01, FIS2011-28853-C02-02, FIS2014-57026-REDT, FIS2014-51948-C2-1-P, and FIS2014-51948-C2-2-P, and the Generalitat Valenciana in the program Prometeo II-2014/068. This work is also partly supported by the National Natural Science Foundation of China under Grant Nos. 11165005, 11565007, 11475227, 11375080 and 11575076. We acknowledge the support of the European Community-Research Infrastructure Integrating Activity Study of Strongly Interacting Matter (acronym HadronPhysics3, Grant Agreement n. 283286) under the Seventh Framework Programme of EU. It is also supported by the Open Project Program of State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, China (No. Y5KF151CJ1). M. D. gratefully acknowledges support from the NSF/PIF Grant No. PHY 1415459 and the NSF/Career grant No. 1452055.Peer reviewe
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