ترغب بنشر مسار تعليمي؟ اضغط هنا

$B_s B^* K $ and $B_s B K^*$ vertices using QCD sum rules

103   0   0.0 ( 0 )
 نشر من قبل Bruno Os\\'orio Rodrigues
 تاريخ النشر 2015
  مجال البحث
والبحث باللغة English




اسأل ChatGPT حول البحث

The form factors and the coupling constant of the $B_s B^* K $ and $B_s B K^*$ vertices are calculated using the QCD sum rules method. Three point correlation functions are computed considering both the heavy and light mesons off-shell in each vertex, from which, after an extrapolation of the QCDSR results at the pole of the off-shell mesons, we obtain the coupling constant of the vertex. The form factors obtained have different behaviors but their simultaneous extrapolation reach the same value of the coupling constant $g_{B_s B^* K}=8.41 pm 1.23 $ and $g_{B_s BK^*}=3.3 pm 0.5$. We compare our result with other theoretical estimates and compute the uncertainties of the method.



قيم البحث

اقرأ أيضاً

Finite energy QCD sum rules with Legendre polynomial integration kernels are used to determine the heavy meson decay constant $f_{B_c}$, and revisit $f_B$ and $f_{B_s}$. Results exhibit excellent stability in a wide range of values of the integration radius in the complex squared energy plane, and of the order of the Legendre polynomial. Results are $f_{B_c} = 528 pm 19$ MeV, $f_B = 186 pm 14$ MeV, and $f_{B_s} = 222 pm 12$ MeV.
The decay bar B -> bar K* (-> bar K pi) l+ l- offers great opportunities to explore the physics at and above the electroweak scale by means of an angular analysis. We investigate the physics potential of the seven CP asymmetries plus the asymmetry in the rate, working at low dilepton mass using QCD factorization at next-to leading order (NLO). The b ->s CP asymmetries are doubly Cabibbo-suppressed lesssim 1 % in the Standard Model and its extensions where the CKM matrix is the only source of CP violation. Three CP asymmetries are T-odd, and can be O(1) in the presence of non-standard CP violation. The T-even asymmetries can reach O(0.1), limited by the small strong phases in the large recoil region. We furthermore point out an easy way to measure CP phases from time-integrated, untagged bar B_d, B_d -> K* (-> K0 pi0) l+ l- and bar B_s,B_s -> phi (-> K+ K-) l+ l- decays. Analyses of these CP asymmetries can rule out, or further support the minimal description of CP violation through the CKM mechanism. Experimental studies are promising for (super) flavor factories and at hadron colliders.
126 - M.E. Bracco , M. Nielsen 2010
We evaluate the mass of the $B_{s0}$ scalar meson and the coupling constant in the $B_{s0} B K$ vertex in the framework of QCD sum rules. We consider the $B_{s0}$ as a tetraquark state to evaluate its mass. We get $m_{B_s0}=(6.04pm 0.08) GeV$, which is bigger than predictions supposing it as a $bbar{s}$ state or a $Bbar{K}$ bound state with $J^{P}=0^+$. To evaluate the $g_{B_{s0}B K}$ coupling we use the three point correlation functions of the vertex, considering $ B_{s0} $ as a normal $bbar{s}$ state. The obtained coupling constant is: $g_{B_{s0} B K} =(16.3 pm 3.2) GeV$. This number is in agreement with light-cone QCD sum rules calculation. We have also compared the decay width of the $BSto BK$ process considering the $BS$ to be a $bbar{s}$ state and a $BK$ molecular state. The width obtained for the $BK$ molecular state is twice as big as the width obtained for the $bbar{s}$ state. Therefore, we conclude that with the knowledge of the mass and the decay width of the $BS$ meson, one can discriminate between the different theoretical proposals for its structure.
263 - T.Mannel , B.D.Pecjak , 2007
We use QCD sum rules to compute matrix elements of the Delta B=2 operators appearing in the heavy-quark expansion of the width difference of the B_s mass eigenstates. Our analysis includes the leading-order operators Q and Q_S, as well as the sublead ing operators R_2 and R_3, which appear at next-to-leading order in the 1/m_b expansion. We conclude that the violation of the factorization approximation for these matrix elements due to non-perturbative vacuum condensates is as low as 1-2%.
Using special linear combinations of finite energy sum rules which minimize the contribution of the unknown continuum spectral function, we compute the decay constants of the pseudoscalar mesons B and B_s. In the computation, we employ the recent thr ee loop calculation of the pseudoscalar two-point function expanded in powers of the running bottom quark mass. The sum rules show remarkable stability over a wide range of the upper limit of the finite energy integration. We obtain the following results for the pseudoscalar decay constants: f_B=178 pm 14 MeV and f_{B_s}=200 pm 14 MeV. The results are somewhat lower than recent predictions based on Borel transform, lattice computations or HQET. Our sum rule approach of exploiting QCD quark hadron duality differs significantly from the usual ones, and we believe that the errors due to theoretical uncertainties are smaller.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا