V. Bashiry

Cyprus International University, Cyprus

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Publications (49)105.4 Total impact

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    ABSTRACT: Rare exclusive $B_c^\ast \rightarrow D_{s}~l^+ l^-$ decays are analyzed in the framework of the three--point QCD sum rules approach. The two gluon condensate corrections to the correlation function are included and the form factors of this transition are evaluated. Using the form factors, the decay width and integrated decay rate for these decays are also calculated.
    10/2014;
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    V. Bashiry, A. Abbasi
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    ABSTRACT: The strong coupling constant g$_{h_{b}B_{c}^{PS}B_{c}^{V}}$ is calculated using the three-point QCD sum rules method. We use correlation functions to obtain these strong coupling constants with contributions of both B$_{c}^{PS} $ and B$_{c}^{V}$mesons as off-shell states. The contributions of two gluon condensates as a radiative correction are considered. The results show that g$_{h_{b}B_{c}^{PS}B_{c}^{V}}=8.80\pm 2.84 GeV^{-1}$and g$_{h_{b}B_{c}^{V} B_{c}^{PS}}=9.34\pm 3.12 GeV^{-1}$ in the $B_{c}^{PS}$ and $B_{c}^{V}$ off-shell state, respectively.
    01/2014;
  • A. Abbasi, V. Bashiry
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    ABSTRACT: The strong coupling constant $g_{\Upsilon B_c^{ps} B_c^V}$ is evaluated using the three-point QCD sum rules. The correlation functions used to calculate these strong coupling constants contain contributions of both $B_c^V$ and $B_c^{ps}$ mesons as off-shell states with contributions of two gluon condensates as a radiative corrections. The results, $g_{\Upsilon B_c^V B_c^{PS}}=1.67\pm 0.52 GeV^{-1}$ for $B_c^{Ps}$ off-shell and $g_{\Upsilon B_c^{PS}B_c^V}=(0.87\pm0.25) GeV^{-1}$ for $B_c^V$ off-shell are obtained for the relevant strong coupling constants
    European Physical Journal A 07/2013; · 2.04 Impact Factor
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    v. Bashiry
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    ABSTRACT: In this study we present the first theoretical calculation of the form factor of the $\chi_{c0}(1P) \rar J/\psi \gamma $ and $\chi_{b0}(1P) \rightarrow \Upsilon(1S) \gamma $ decays in the frame work of QCD sum rules. We also find branching ratio ${\cal B}_r(\chi_{c0}(1P) \rightarrow J/\psi \gamma)=(1.07\times \pm 0.14) \times 10^{(-2)} $ which is in agreement with the experimental data. Furthermore, we estimate the $\Gamma_{tot}(\chi_{b0}(1P)) =5.5\pm 0.5 $ MeV, where experimental bound for full width of $\chi_{b0}$ is $\Gamma_{tot}(\chi_{b0}(1P)) <6 $ MeV.
    05/2013;
  • V Bashiry, K Azizi, S Sultansoy
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    ABSTRACT: The heavy fourth generation of quarks that have sufficiently small mixing with the three known SM families form hadrons. In the present work, we calculate the masses and decay constants of mesons containing either both quarks from the fourth generation or one from fourth family and the other from observed SM quarks, namely charm or bottom quark, in the framework of the QCD sum rules. In the calculations, the two gluon condensate diagrams as nonperturbative contributions are taken into account. The obtained numerical results are reduced to the known masses and decay constants of the b and c quarkonia, when the fourth family quark is replaced by the bottom or charm quark.
    Journal of Physics Conference Series 02/2012; 347(1):012027.
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    V. Bashiry, K. Azizi
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    ABSTRACT: Using form factors enrolled to the transition matrix elements and calculated via light-cone QCD sum rules including next-to-leading order corrections in the strong coupling constant, we provide a systematic analysis of the $ B_s\rightarrow f_0 (980)\ell^+\ell^- $ both in the standard and universal extra dimension models. In particular, we discuss sensitivity of the differential branching ratio and various double lepton polarization asymmetries on the compactification factor of extra dimension and show how the results of the extra dimension model deviate from the standard model predictions. The order of branching ratio makes this decay mode possible to be checked at LHCb in near future.
    12/2011;
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    V.bashiry, M.bayar, K.azizi
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    ABSTRACT: In this paper, we compare the branching ratio and rate difference of electron channel to muon channel of and B →K*ℓ+ℓ- decays, where is the p-wave scalar meson, in the supersymmetric models. MSSM with R parity is considered since considerable deviation from the standard model predictions can be obtained in B→Xs ℓ-ℓ+. Taking CQ1 and CQ2 about one which is consistent with the B→K*μ+μ- rate at low dileptonic invariant mass region (1 ≤ q2 ≤ 6 GeV2). It is found that, firstly, the decay is measurable at LHC, secondly, in comparison with B →K*ℓ+ ℓ- decay a greater deviation in the decay can be seen. Measurement of these observables for the semileptonic rare , in particular, at low q2 region can give valuable information about the nature of interactions within Standard Model or beyond.
    Modern Physics Letters A 11/2011; 26(12). · 1.11 Impact Factor
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    V. Bashiry
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    ABSTRACT: The mass and decay constant of the ground state of spin singlet $b \bar{b}$ is calculated by using the QCD sum rules method. This meson is an axial vector $P$-wave named $h_b(1P)$ meson with $J^P =1^+$. It is found that the mass of this meson is $(m=9940\pm 37)$ MeV, which is consistent with the recent experimental data by Belle collaboration.
    Physical review D: Particles and fields 09/2011; 84.
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    V. Bashiry, K. Azizi, S. Sultansoy
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    ABSTRACT: The heavy fourth generation of quarks that have sufficiently small mixing with the three known SM families form hadrons. In the present work, we calculate the masses and decay constants of mesons containing either both quarks from the fourth generation or one from fourth family and the other from known third family SM quarks in the framework of the QCD sum rules. In the calculations, we take into account two gluon condensate diagrams as nonperturbative contributions. The obtained results reduce to the known masses and decay constants of the $\bar b b$ and $\bar c c$ quarkonia when the fourth family quark is replaced by the bottom or charm quark.
    Physical review D: Particles and fields 04/2011; 84.
  • H Daĝ, K Azizi, V Bashiry
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    ABSTRACT: In this work, the semileptonic decays of the scalar charmonium state Xc0 and the pseudo scalar charmonia states ηc(1s) and ηc(2s) into Ds and D mesons are analyzed. The form factors of the transitions Xc0 → Ds(D)ℓν and ηc(1s, 2s) → Ds(D)ℓν are calculated within the framework of the three-point QCD sum rules. The results of the form factors are used to estimate the decay widths of the charmonia states into and .
    Journal of Physics G Nuclear and Particle Physics 05/2010; 37(7):075005. · 5.33 Impact Factor
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    ABSTRACT: We present the first study of CP asymmetry in Λb → Λℓ+ ℓ− decay when a new weak phase comes through the extension of three-generation standard model to the four-generation standard model. Taking |Vt's* Vt'b| = 0.01, 0.02, 0.03 with phase {60° − 120°}, which is consistent with the b → sℓ+ℓ− rate and the Bs mixing parameter ΔmBs, we find out that CP asymmetry is quite sensitive to the existence of fourth generation. It can serve as a good tool to search for new physics effects, in particular, to search for the fourth generation quarks (t', b') via their indirect manifestations in loop diagrams.
    Chinese Physics Letters 03/2010; 27(4):041201. · 0.92 Impact Factor
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    T M Aliev, K Azizi, V Bashiry
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    ABSTRACT: The mass and decay constant of the ground state strange tensor meson K*2(1430) with I(JP) = 1/2(2+) are calculated using the QCD sum rules method. The results are consistent with the experimental data. It is found that SU(3) symmetry breaking effect constitutes about 20% of the decay constant.
    Journal of Physics G Nuclear and Particle Physics 01/2010; 37(2):025001. · 5.33 Impact Factor
  • V. Bashiry, K. Azizi
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    ABSTRACT: The mass eigen states K 1(1270) and K 1(1400) are mixture of the strange members of two axial-vector SU(3) octet, 3 P 1(K A 1) and 1 P 1(K B 1). Taking into account this mixture, the forward-backward asymmetry(A FB ), branching ratio(Br) and rate difference of electron channel to muon channel(R) of B → K 1(1270, 1400)ℓ+ℓ− transitions are studied in the framework of different supersymmetric models. MSSM with R parity is considered because considerable deviation from the standard model predictions can be obtained in B → X s ℓ−ℓ+. Taking C Q1 and C Q2 about one which is consistent with the B → K*μ+μ− rate at low dileptonic invariant mass region(1 ≤ q 2 ≤ 6GeV2), we obtain a size able deviation for A FB , Br and R with respect to the Standard Model results. Any measurement of physical observables and their comparison with the results obtained in this paper can gives useful information about the nature of interactions beyond the standard model.
    Journal of High Energy Physics 01/2010; 2010(1):1-18. · 5.62 Impact Factor
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    ABSTRACT: In this paper we present a study of CP asymmetry, single lepton polarization asymmetry and polarized CP asymmetry in B→K*ℓ+ℓ- decay within the four-generation standard model. Taking |Vt′s*Vt′b|=0.01, 0.02, 0.03 with phase {60°–120°}, which is consistent with the b→sℓ+ℓ- rate and the Bs mixing parameter ΔmBs, we find that CP asymmetry, single lepton polarization asymmetry and polarized CP asymmetry are sensitive to the existence of the fourth generation. This can serve as an indirect method to search for new physics effects, in particular, to search for the fourth-generation quarks(t′,b′) via their indirect manifestations in loop diagrams.
    Physical review D: Particles and fields 07/2009; 80(1).
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    V. Bashiry
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    ABSTRACT: We study the single and double lepton polarization asymmetries in the semileptonic B meson decays B → K1(1270)ℓ+ℓ− ℓ≡e, μ, τ), where the strange P-wave meson, K1(1270), is the mixtures of the K1A and K1B, which are the 13P1 and 11P1 states, respectively. The lepton polarization asymmetries show relatively strong dependency in the various region of dileptonic invariant mass. The lepton polarization asymmetries can also be used for determining the K1(1270)–K1(1400) mixing angle, θK1 and new physics effects. Furthermore, it is shown that these asymmetries in B → K1(1270)ℓ+ℓ− decay compared with those of B → K*ℓ+ℓ− decay are more sensitive to the dileptonic invariant mass.
    Journal of High Energy Physics 06/2009; 2009(06):062. · 5.62 Impact Factor
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    V. Bashiry, K. Azizi
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    ABSTRACT: The mass eigen states $K_1(1270)$ and $K_1(1400)$ are mixture of the strange members of two axial-vector SU(3) octet, $^3P_1(K_1^A)$ and $^1P_1(K_1^B)$. Taking into account this mixture, the forward-backward asymmetry and branching ratio of $B \rar K_1(1270,1400) \ell^+ \ell^-$ transitions are studied in the framework of different supersymmetric models. It is found that the results have considerable deviation from the standard model predictions. Any measurement of these physical observables and their comparison with the results obtained in this paper can give useful information about the nature of interactions beyond the standard model. Comment: 14 pages, 4 figures
    03/2009;
  • V. Bashiry, K. Zeynali
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    ABSTRACT: We investigate the influence of the universal extra dimension on the branching ratio in the B→π(ρ)ℓ+ℓ- decay. Taking 1/R∼{200–1000} GeV with one universal extra spatial dimension, which is consistent with the experimental data for B(B→Xsγ), B(B→K*μ+μ-) and the electroweak precision tests, we obtain that for both (μ,τ) channels the branching ratio strongly depends on the compactification radius 1/R.
    Physical review D: Particles and fields 02/2009; 79(3).
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    V. Bashiry, M. Bayar
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    ABSTRACT: In this study a systematical analysis of various polarization asymmetries in inclusive b→s ℓ + ℓ − decay in the standard model (SM) with four generation of quarks is carried out. We found that the various asymmetries are sensitive to the new mixing and quark masses for both of the μ and τ channels. Sizable deviations from the SM values are obtained. Hence, b→s ℓ + ℓ − decay is a valuable tool for searching physics beyond the SM, especially in the indirect searches for the fourth-generation of quarks (t′,b′).
    European Physical Journal C 01/2009; 61(3):451-459. · 5.25 Impact Factor
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    V. Bashiry, K. Zeynali
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    ABSTRACT: We investigate the influence of the universal extra dimension on the branching ratio in the B()l{sup +}l decay. Taking 1/R(200-1000) GeV with one universal extra spatial dimension, which is consistent with the experimental data for B(BX{sub s}), B(BK*{sup +}) and the electroweak precision tests, we obtain that for both (,) channels the branching ratio strongly depends on the compactification radius 1/R.
    Physical review D: Particles and fields 01/2009; 79(3):033006-033006.
  • Vali Bashiry
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    ABSTRACT: It is known that the Standard Model (SM) does not predict the number of fermion families; N. The only restriction comes from the asymptotic freedom of QCD which requires the number of quarks to be less than 17 and, therefore, the number of SM families to be N ⩽ 8. Before 1990Šs, many authors published articles related to the extra SM families and their phenomenological consequences. In early 1990Šs, the LEP data yields N is almost 3 where the neutral lepton mass for each family is less than half the mass of the Z boson. Generally, this result is interpreted as the exact value of N, since one assumes that the neutrinos must have very small masses. If we disregard this incorrect assumption, the LEP data does not exclude the existence of extra SM families with heavy neutrinos. Meanwhile, few papers arguing the existence of the fourth SM family have been publishing. These arguments are based on the ÂŚflavor democracyŠ hypothesis. The study of FCNC in B decays can indirectly shed light on the SM4 family in quark sector and LFV is a good candidate to indirect search for 4th generation of leptons.
    AIP Conference Proceedings. 04/2008; 1006(1):146-149.