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Dynamical Analysis of V-particles Decays

Dynamical Analysis of V-particles Decays. Podolanski-Armenteros Plot and its application for V0 particle search. Jaw-Luen Tang Department of Physics National Chung Cheng University Chiayi, Taiwan. Introduction.

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Dynamical Analysis of V-particles Decays

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  1. Dynamical Analysis of V-particles Decays Podolanski-Armenteros Plot and its application for V0 particle search Jaw-Luen Tang Department of Physics National Chung Cheng University Chiayi, Taiwan

  2. Introduction • In 1953, Podolanski and Armenteros devised a method of analyzing the dynamics of two-body V decays to search for new unstable neutral particles in terms of measured quantities: p1, p2. (pp1+p2) • The method based on constructing new variables: 1/P , Podolanski-Arementeros parameter a , pT the transverse momentum ore=2pT/P, that related to the momentum components of each particles by conservation of momentum and energy which depend on the decay schemes. • It is used to classify the V0-particles and is a convenient way of displaying ( identifying ) the decay schemes. p1 p2

  3. Armenteros analysis of V decay • Consider the decays of a neutral V0-particle of massmand velocity b into two charged particles with mass m1 and m2 , m m1 + m2 + Q. Laboratory system Center of Mass system

  4. Armenteros Analysis • In the laboratory system, only p1,p2,and p can be measured, while the velocity of decaying particle b is unknown. • Useful quantities : pT, independent of b. • In the a-pT or a-eplanes, the points corresponding to a given decay scheme lie on an family of ellipses determined by the particle mass and the velocity b the secondaries.

  5. An Example: E896 H search

  6. KSππ Λpπ +(1540) -> p Ks Armenteros plot Decay chain + Ks + Ks - p Λ Λ Another Example: HERA-B • HERA-B try to verify claims for different exotic states, mainly they focus on:+ (uudds) -> p K0 Taken from A. Sbrizzi‘s talk

  7. ql(+) - ql(-)  = qt(+) ql(+) + ql(-) q(+) ql(+) qt(-) ql(-) q(-) Another example:Study of the K*(892)0 signal in pp ALICE events Taken from Giuseppe’s talk.

  8. More example:Exotic Particle Searches with STAR at RHIC Taken from Sonia Kabana’s talk

  9. LEPS: 10k L + 10k f events • Analyzed 10k L + 10k f MC events through current TPCana0.43 tracking and vertex finder codes. 10k f 10k L 10k L + 10k f gp->fp gpLK+

  10. Cuts at invariant mass Cut1 f nvtx >1, ntrk>4, cdis<2mm, chi2prob<0.02 Cut 2 Ks Cut 3 L Cut5 Cuts 1, in target, Vtxy<2mm -1650Vz<-1550 Cut4 f Cuts 1, in target, Vtxy<2mm -1650Vz<-1550 Cut 6 Cuts 1, out target Vtxy>2mm -1650Vz<-1550 Cut7 pT<0.2, |a|<0.5 f arm cut Cut8 pT>0.1, |a|<1 Ks arm cut Cut9 pT<0.2,a>0.5 L arm cut Cut10 Cuts 1& 4& 7 f Cut11 Cuts 2 & 5 & 8 Ks Cut12 Cuts 3&6&9 L

  11. Data Cuts at Armenteros diagram Cut1 nvtx >1 Cut 2 Cut 1 + ntrk>4 Cut 3 Cuts 1+2 q1q2<0, cdis<2mm, chi2prob<0.02 Cut4 Cuts 1+2+3 [a, pt]<1 Cut 5 Cuts 4 && in target Vtxy<2mm, Vz cut Cut 6 Cuts 4 && out target Vtxy>2mm, Vz cut Cut8 Cuts 4 and Ks arm cut Cut7 Cut 4 and f arm cut Cut9 Cut 4 and L arm cut Cut12 Cuts 9 and L arm cut Cut10 Cuts 5 and f arm cut Cut11 Cuts 5 and Ks arm cut

  12. Runs 28641 To 28847

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