نتایج جستجو برای: who standard

تعداد نتایج: 1256149  

2008
John Donoghue John F. Donoghue

Many of the classic problems of particle physics appear in a very different light when viewed from the perspective of the multiverse. Most importantly the two great “fine tuning” problems that motivate the field are far less serious when one accounts for the required anthropic constraints which exist in a multiverse. However, the challenge then becomes to construct a realistic physical theory o...

2007
GUIDO ALTARELLI

We present some recent developments on model building for neutrino masses and mixings. In particular, we review tri-bimaximal neutrino mixing derived from discrete groups, notably A4. We discuss the problems encountered with extending the symmetry to the quark sector and with Grand Unification.

2008
Virendra Gupta

It is suggested that the narrow meson state seen in the the SELEX experiment is a (cs̄ss̄) tetraquark state. Characteristics of other possible tetraquarks formed out of c and s quarks and antiquarks are considered. SELEX experiment has reported [1] a puzzling narrow meson state at a mass of 2632.6± 1.6 MeV/c which decays preferentially to D s (cs̄) + η(548) rather than to D(cd̄)+K or D(cū)+K. In th...

2008
Adam Bzdak

Small momentum transfer elastic pion-proton cross-section at high energies is calculated assuming the proton is composed of two constituents, a quark and a diquark. We find that it is possible to fit very precisely the data when (i) the pion acts as a single entity (no constituent quark structure) and (ii) the diquark is rather large, comparable to the size of the proton.

1998
Dietrich Wegener

The high energy physics program (Ecms ≤ 8.6GeV ) at DORIS was initiated by the PLUTO collaboration which sent its proposal to the Forschungskollegium June 30, 1977 [1]. The same day the observation of the Υ(9.46) resonance was announced to the public in a seminar at FNAL [2]. The physics program proposed by PLUTO included the measurement of σtot and the search for charm and τ . The search for a...

1997
Yoshio Koide

A seesaw mass matrix model is reviewed as a unification model of quark and lepton mass matrices. The model can understand why topquark mass mt is so singularly enhanced compared with other quark masses, especially, why mt ≫ mb in contrast to mu ∼ md, and why only top-quark mass is of the order of the electroweak scale ΛW , i.e., mt ∼ O(ΛW ). The model predicts the fourth up-quark t′ with a mass...

Journal: :desert 2010
s. modallaldoust

a watershed management program is usually based on the results of watershed modeling. accurate modeling results are decided by the appropriate parameters and input data. precipitation is the most important input for watershed modeling. precipitation characteristics usually exhibit significant spatial variation, even within small watersheds. therefore, properly describing the spatial variation o...

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