Papers by Hossein Mehraban
arXiv (Cornell University), Jun 12, 2015
We calculate the branching ratio of the non-resonant B → D − π + π + π − decay using a simple mod... more We calculate the branching ratio of the non-resonant B → D − π + π + π − decay using a simple model based on the framework of the factorization approach where one can ommit the nonfactorization effects. In naive factorization approach, there are only two tree diagrams for this decay mode. In the first diagram, the matrix element of decay mode is factorized into a B → D form factor multiplied by a 3π decay constant and in the second diagram, the matrix element is factorized into a B → Dπ form factor multiplied by a 2π decay constant, We assume that in the rest frame of B meson, the D meson remains stationary, so we obtain the value (3.47 ± 0.14) × 10 −3 for the branching ratio of the B → D − π + π + π − decay mode, while the experimental results are (3.9 ± 1.9) × 10 −3 .
arXiv: High Energy Physics - Phenomenology, Sep 28, 2021
X (3872) because of its mass that is just below 0 D *0 D threshold and its quantum number 1 PC J ... more X (3872) because of its mass that is just below 0 D *0 D threshold and its quantum number 1 PC J can be considered as a weakly bound molecule. It can be regarded as non-relativistic system depicting universality and compositeness. Physical observables are called universal if they are insensitive to the range and other details of short-range interaction. Weinberg introduced compositeness criterion to classify a two-body composite system as the sum, with different weights , of a compact core and a two distinct parts.
Physics of Particles and Nuclei Letters
Physical Review D
{"data":{"abstract":{"value":"<p>The current analysis aims to present the results of a QCD analys... more {"data":{"abstract":{"value":"<p>The current analysis aims to present the results of a QCD analysis of diffractive parton distribution functions (PDFs) at next-toleading-order accuracy in perturbative QCD. In this new determination of diffractive PDFs, we use all available and up-to-date diffractive deep-inelastic scattering (DIS) datasets from H1 and ZEUS collaborations at HERA, including the most recent <math xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mrow><mi mathvariant=\"normal\">H</mi><mn>1</mn><mo>/</mo><mi>ZEUS</mi></mrow></math> combined measurements. In this analysis, we consider the heavy quark contributions to the diffractive DIS in the so-called framework of the <span class=\"sc\">fonll</span> general mass variable flavor number scheme. The uncertainties on the diffractive PDFs are calculated using the standard "Hessian error propagation," which served to provide a more realistic estimate of the uncertainties. This analysis is enriched, for the first time, by including the nonperturbative higher twist (HT) effects in the calculation of diffractive DIS cross sections, which are particularly important at <math xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mi>large</mi><mtext>−</mtext><mi>x</mi></math> and low <math xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><msup><mi>Q</mi><mn>2</mn></msup></math> regions. Then, the stability and reliability of the extracted diffractive PDFs are investigated upon the inclusion of HT effects. We discuss the novel aspects of the approach used in this QCD fit, namely, optimized and flexible parametrizations of diffractive PDFs, the inclusion of HT effects, and considering the recent <math xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mrow><mi mathvariant=\"normal\">H</mi><mn>1</mn><mo>/</mo><mi>ZEUS</mi></mrow></math> combined dataset. Finally, we present the extracted diffractive PDFs with and without the presence of HT effects and discuss the fit quality and the stability upon variations of the kinematic cuts and the fitted datasets. We show that the inclusion of HT effects in diffractive DIS can improve the description of the data, which leads, in general, to a very good agreement between data and theory predictions.
Physics of Particles and Nuclei Letters
Mathematical Methods in the Applied Sciences
EPL (Europhysics Letters)
Physical Review D, 2017
Prompt photon production is known as a powerful tool for testing perturbative QCD predictions and... more Prompt photon production is known as a powerful tool for testing perturbative QCD predictions and also the validity of parton densities in the nucleon and nuclei especially of the gluon. In this work, we have performed a detailed study on this subject focusing on the isolated prompt photon production in p-Pb collisions at forward rapidity at the LHC. The impact of input nuclear modifications obtained from different global analyses by various groups on several quantities has been investigated to estimate the order of magnitude of the difference between their predictions. We have also studied in detail the theoretical uncertainties in the results due to various sources. We found that there is a remarkable difference between the predictions from the nCTEQ15 and other groups in all ranges of photon transverse momentum p γ T. Their differences become more explicit in the calculation of the nuclear modification ratio and also the yield asymmetry between the forward and backward rapidities rather than single differential cross sections. We emphasize that future measurements with ALICE will be very useful not only for decreasing the uncertainty of the gluon nuclear modification, but also to accurately determine its central values, especially in the shadowing region.
Veterinary research forum : an international quarterly journal, 2016
Peroxisome proliferator-activated receptors (PPARs) are a member of nuclear receptors superfamily... more Peroxisome proliferator-activated receptors (PPARs) are a member of nuclear receptors superfamily, which mainly regulate the expression of target genes involved in lipid and energy metabolism. These receptors are divided to three isotypes: PPARα, PPARγ and PPARβ/δ. Each isotype has a distinct tissue distribution relating to the distinct functions. In this study, the mRNA abundance for PPARα, PPARγ and PPARβ/δ was evaluated and compared with high and low motile ram spermatozoa. Semen samples from 6 adult rams were fractionated on a two layer discontinuous Percoll gradient to high and low motile sperm and quantitative parameters of sperm motility were determined by CASA. Total RNA was extracted and the mRNA abundance for each gene was measured by relative quantification technique with Real time PCR. The levels of three isotypes of PPAR transcripts were significantly higher in high motile semen samples using quantitative RT-PCR. Some of sperm motility indices were also significantly co...
International Journal of Modern Physics A, 2016
In this paper, we analyzed the process of [Formula: see text] decay within QCD factorization (QCD... more In this paper, we analyzed the process of [Formula: see text] decay within QCD factorization (QCDF) and final state interaction (FSI) effects. At first, the [Formula: see text] decay is calculated via QCDF approach. The result that is found by using the QCDF method is less than the experimental result. Then we considered FSI effect as a sizable correction where there are the intermediate state [Formula: see text] mesons via the exchange of [Formula: see text]. The experi mental branching ratio of [Formula: see text] decay is [Formula: see text], and our results by QCDF and FSI are [Formula: see text] and [Formula: see text], respectively.
Progress of Theoretical and Experimental Physics, 2015
In this paper, we analyze the hadronic decay of B + c → J/ψ a 1 (1260) + in a perturbative QCD ap... more In this paper, we analyze the hadronic decay of B + c → J/ψ a 1 (1260) + in a perturbative QCD approach (pQCD), where a 1 (1260) is an axial-vector meson and J/ψ is a vector meson. The experimental data for the branching ratio of this decay are less than (1.2 × 10 −3). We find that the branching ratio is (1.02 +0.04+0.03+0.01 −0.08−0.05−0.01) × 10 −3 and that it has a good agreement with the experimental result.
Canadian Journal of Physics, Sep 8, 2014
We investigate the B 0 ¡ D * ͑2007͒ 0 ϩ Ϫ decay using Dalitz plot analysis. There are two tree di... more We investigate the B 0 ¡ D * ͑2007͒ 0 ϩ Ϫ decay using Dalitz plot analysis. There are two tree diagrams for this decay mode in the factorization approach: the transition matrix element is factorized into a B 0 ¡ + − form factor multiplied by D * ͑2007͒ 0 decay constant; and a B 0 ¡ D * ͑2007͒ 0 Ϫ form factor multiplied by a + decay constant. In this research we evaluate the matrix elements of the vector and axial vector currents between the B 0 and D * ͑2007͒ 0 Ϫ meson states by using the B* + pole. The contributions of intermediate resonances, such as f 0 (980), f 0 (1370), f 0 (1500) and (770), (1450), (1700), have been taken into account. According to the QCD factorization approach and using Dalitz plot analysis, we calculate the branching ratio of B 0 ¡ D * ͑2007͒ 0 ϩ Ϫ decay and obtain 3.81 ± 1.31 × 10 −4 and 7.49 ± 2.71 × 10 −4 at the = m b and 2m b scales, respectively, whereas the experimental result is (6.20 ± 2.20) × 10 −4 .
The Journal of High Energy Physics, 2011
International Journal of Modern Physics A, 2015
In this paper, we analyzed the decay [Formula: see text] within QCD factorization (QCDF) and fina... more In this paper, we analyzed the decay [Formula: see text] within QCD factorization (QCDF) and final state interaction (FSI) methods. At first, we consider the QCDF approach, where the final states are a pseudoscalar meson and vector meson. Then, we consider the FSI method where the intermediate states are [Formula: see text] and [Formula: see text] via the exchange of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] to improve the branching ratio. The above intermediate states are calculated by using the QCDF method. In the FSI effects, the results of our calculations depend on [Formula: see text] as the phenomenological parameter. The experimental branching ratio of this decay is [Formula: see text]. Our results in QCDF approach is [Formula: see text], and with [Formula: see text], the improved branching ratio is [Formula: see text].
Advances in High Energy Physics, 2012
J Phys G Nucl Particle Phys, 2012
Iranian Journal of Physics Research, Dec 15, 2014
In this research we describe effective Hamiltonian theory and apply this theory to the calculatio... more In this research we describe effective Hamiltonian theory and apply this theory to the calculation of current-current $Q_{12}$ and QCD penguin $Q_{3...6}$ decay rates We calculate the decay rates of semileptonic and hadronic of charm quark in effective Hamiltonian theory. We investigate the decay rates of D meson decays according to Spectator Quark Model(SQM) for the calculation of D meson
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Papers by Hossein Mehraban