Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userBranching fractions and polarizations of $Dto V(omega,rho, K^*) ell u_ell$ within QCD LCSR
83
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
In this paper, we make a detailed study about the $Dto V$ helicity form factors (HFFs) within the framework of QCD light-cone sum rule (LCSR) up to twist-4 accuracy. After extrapolating the LCSR predictions of HFFs to the whole physical $q^2$-region, we get the longitudinal, transverse and total $|V_{cq}|$-independent decay widths of semileptonic decay $Dto Vell^+ u_ell$. Meanwhile, the branching fractions of these decays are also obtained by using the $D^0(D^+)$-meson lifetime, which agree well with the BES-III results within errors. As a further step, we also investigate the differential and mean predictions for charged lepton (vector meson) polarization in the final state $P_{rm L,T}^ell$ ($F_{rm L,T}^ell$), the forward-backward asymmetry ${cal A}_{rm FB}^ell$, and the lepton-side convexity parameters ${cal C}_{rm F}^ell$. Our predictions are consistent with Covariant Confining Quark Model results within the errors. Thus, we think the LCSR approach for HFFs is applicable for dealing with the $D$-meson semileptonic decays.
rate research
Read More
The axial-vector $a_1(1260)$-meson longitudinal twist-2 distribution amplitude $phi_{2;a_1}^| (x,mu )$ within the framework of QCD sum rules under the background field theory is investigated. By considering the vacuum condensates up to dimension-six and the perturbative part up to next-to-leading order QCD corrections, the moments at initial scale $mu_0=1~{rm GeV}$ are $langle xi_{2;a_1}^{|;2}rangle |_{mu_0} = 0.210 pm 0.018$, $langle xi_{2;a_1}^{|;4}rangle |_{mu_0} = 0.091 pm 0.007$, and $langle xi_{2;a_1}^{|;6}rangle |_{mu_0} = 0.052 pm 0.004$ respectively. Secondly, the transition form factors (TFFs) for $Dto a_1(1260)$ under the light-cone sum rules are given. When taking squared momentum transfer to zero, we obtain $ A(0) = 0.130_{ - 0.015}^{ + 0.013}$, $V_1(0) = 1.899_{ - 0.127}^{ + 0.119}$, $V_2(0) = 0.211_{ - 0.020}^{ + 0.018}$, and $V_0(0) = 0.235_{ - 0.025}^{ + 0.026}$. With the extrapolated TFFs for the physically allowable region, the differential decay widths and total branching ratios for the processes $D^{0(+)} to a_1^{-(0)}(1260)ell^+ u_ell$ can be obtained, i.e. ${cal B}(D^0to a_1^-(1260) e^+ u_e) = (5.421_{-0.697}^{+0.702}) times 10^{-5}$, ${cal B}(D^+to a_1^0(1260) e^+ u_e) = (6.875_{-0.884}^{+0.890}) times 10^{-5}$, ${cal B}(D^0to a_1^-(1260) mu^+ u_mu)=(4.864_{-0.641}^{+0.647}) times 10^{-5}$, ${cal B}(D^+ to a_1^0(1260) mu^+ u_mu)=(6.169_{-0.821}^{+0.813}) times 10^{-5}$.
The heavy quark effective field theory (HQEFT) provides an effective way to deal with the heavy meson decays. In the paper, we adopt two different correlators to derive the light-cone sum rules of the $B to pi$ transition form factors (TFFs) within the framework of HQEFT. We label those two LCSR results as LCSR-${cal U}$ and LCSR-${cal R}$, which are for conventional correlator and right-handed correlator, respectively. We observe that the correlation parameter $|rho_{rm RU}|$ for the branching ratio ${cal B}(B to pi l u_{l})$ is $sim 0.85$, implying the consistency of the LCSRs under different correlators. Moreover, we obtain $|V_{rm ub}|_{{rm LCSR}-{cal U}}=(3.45^{+0.28}_{-0.20}pm{0.13}_{rm{exp}})times10^{-3}$ and $|V_{rm ub}|_{{rm LCSR}-{cal R}} =(3.38^{+0.22}_{-0.16} pm{0.12}_{rm{exp}})times10^{-3}$. We then obtain $mathcal{R}_{pi}|_{{rm LCSR}-{cal U}}=0.68^{+0.10}_{-0.09}$ and $mathcal{R}_{pi}|_{{rm LCSR}-{cal R}}=0.65^{+0.13}_{-0.11}$, both of them agree with the Lattice QCD predictions. Thus the HQEFT provides a useful framework for studying the $B$ meson decays. Moreover, by using right-handed correlator, the twist-2 terms shall dominant the TFF $f^+(q^2)$, which approaches over $sim97%$ contribution in the whole $q^2$-region; and the large twist-3 uncertainty for the conventional correlator is greatly suppressed. One can thus adopt the LCSR-${cal R}$ prediction to test the properties of the various models for the pion twist-2 distribution amplitudes.
Using 482~pb$^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass energy of $sqrt{s} = 4.009$ GeV with the BESIII detector, we measure the branching fractions of the decays $D_s^+tomu^+ u_mu$ and $D_s^+totau^+ u_tau$. By constraining the ratio of decay rates of $D_s^+$ to $tau^+ u_tau$ and to $mu^+ u_mu$ to the Standard Model prediction, the branching fractions are determined to be $mathcal{B}(D_s^+ to mu^+ u_mu) = (0.495 pm 0.067 pm 0.026)%$ and $mathcal{B}(D_s^+ to tau^+ u_tau) = (4.83 pm 0.65 pm 0.26)%$. Using these branching fractions, we obtain a value for the decay constant $f_{D_s^+}$ of $(241.0 pm 16.3 pm 6.5)~text{MeV}$, where the first error is statistical and the second systematic.
Using $e^+e^-$ annihilation data taken at the CESR collider with the CLEO-c detector, measurements of two main $Omega^-$ branching fractions have been made using the reaction $psi(2S)toOmega^-overline{Omega}^+$, hyperon pair production at $sqrt{s}=3.69$~GeV, the peak of the $psi(2S)$ resonance. $Omega^-$ decay channels are identified through momentum distributions of charged particles, and systematics of the $Omega^-$ branching fractions have been studied. The result gives: $mathcal{B}(Omega^- to Lambda^0 K^-) = (68.9pm9.5pm4.3)%$, and $ mathcal{B}(Omega^- to Xi^0 pi^-) = (19.0pm4.0pm1.2)%$.
We develop a methodology for the computation of the $Kto ell u_ell ell^+ ell^-$ decay width using lattice QCD and present an exploratory study here. We use a scalar function method to account for the momentum dependence of the decay amplitude and adopt the infinite volume reconstruction (IVR) method to reduce the systematic errors such as the temporal truncation effects and the finite-volume effects. We then perform a four-body phase-space integral to obtain the decay width. The only remaining technical problem is the possible power-law finite-volume effects associated with the process of $Ktopipi ell u_ellto ell u_ell ell^+ ell^-$, where the intermediate state involves multiple hadrons. In this work, we use a gauge ensemble of twisted mass fermion with a pion mass $m_pi=352$ MeV and a nearly-physical kaon mass. At this kinematics, the $pipi$ in the intermediate state cannot be on shell simultaneously as $2m_pi>m_K$ and the finite-volume effects associate with $pipi$ state are exponentially suppressed. Using the developed methods mentioned above, we calculate the branching ratios for four channels of $Kto ell u_ellell^+ ell^-$, and obtain the results close to the experimental measurements and ChPT predictions. Our work demonstrates the capability of lattice QCD to improve Standard Model prediction in $Kto ell u_ell ell^+ ell^-$ decay width.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
