Collins and Sivers asymmetries in muonproduction of pions and kaons off transversely polarised protons

Measurements of the Collins and Sivers asymmetries for charged pions and charged and neutral kaons produced in semi-inclusive deep-inelastic scattering of high energy muons off transversely polarised protons are presented. The results were obtained using all the available COMPASS proton data, which were taken in the years 2007 and 2010. The Collins asymmetries exhibit in the valence region a non-zero signal for pions and there are hints of non-zero signal also for kaons. The Sivers asymmetries are found to be positive for positive pions and kaons and compatible with zero otherwise. © 2015

New results on the proton spin-dependent structure function g1pg^{p}_{1} at COMPASS with E=200E = 200 GeV

New results of the double spin asymmetry A p 1 and the spin-dependent structure function of the proton g p 1 as a function of x Bj and Q 2 will be presented. New COMPASS data on longitudinal polarized NH 3 target were collected during the year 2011 with a beam of positive muons with energy E = 200 GeV. It allows us to cover low x region down to 0 : 0025 in the range Q 2 > 1 GeV = c 2 for the first tim

Polarised Drell-Yan measurements at COMPASS-II

The spin structure of the nucleon including the Parton Distribution Functions (PDFs) is an im- portant subject studied by the COMPASS experiment at CERN (SPS). The transverse momentum dependent parton distribution functions (TMD PDFs) of the proton and deuteron from Semi- Inclusive Deep Inelastic Scattering (SIDIS) have been studied so far. The Drell-Yan (DY) pro- cess is a complementary way to access the TMD PDFs, using a transversely polarised target. Studying the angular distributions of dimuons from the DY events produced in the scattering of a 190 GeV = c momentum negative pion beam off a transversely polarised proton target (NH 3 ) we are able to extract the azimuthal spin asymmetries, each containing a convolution of two PDFs, one from the target quark and one from the beam anti-quark. Disentangling the contributions from these two PDFs we can access four of the eight TMD PDFs needed to describe the nucleon structure at leading order QCD, like the Sivers and the Boer-Mulders functions. The opportunity to study, in the same experiment, the TMD PDFs from both SIDIS and DY processes is unique at COMPASS. An important QCD prediction - the expected sign change in Sivers and Boer-Mulders functions when accessed by DY and SIDIS – will be checked [ 1 , 2 ]. The COMPASS II Proposal [ 3 ] was approved by CERN for the first period of three years including one year for polarised DY; the beginning of the DY data taking with the proton target is scheduled for 2014 and it can be resumed for one more year after 2017. The feasibility of the measurement was proven by several beam tests done so far. One of the major goals of the COMPASS-II experiment is to perform the first ever polarised DY experiment

Measurement of the longitudinal spin structure of the proton at COMPASS

Inclusive ($A_{1,p}$) and semi-inclusive ($A^{\pi +}_{1,p}$, $A^{\pi -}_{1,p}$, $A^{K+}_{1,p}$ and $A^{K-}_{1,p}$) double-spin asymmetries in deepinelastic muon-proton scattering have been measured at COMPASS (SPS CERN). The results have been obtained with data collected in 2007 for the longitudinal polarised NH$^{3}$ solid target and beam of positive muons with energy $E =$ 160 GeV. We improve the statistical precision of $g^{p}_{1} (x.Q^{2})$ by a factor of two in the low $x$ region. Proton asymmetries have been combined with published deuteron ones to extract the non-singlet spin-dependent structure function $g^{NS}_{1} (x,Q^{2})$. The first moment $\Gamma^{NS}_{1}$ confirms the validity of the Bjorken sum-rule. Our new semi-inclusive data were used to evaluate the $\Delta u$, $\Delta d$, $\Delta\bar{u}$, $\Delta\bar{d}$ and $\Delta s\equiv \Delta\bar{s}$ distributions

Search for exclusive photoproduction of Z(c)(+/-) (3900) at COMPASS

A search for the exclusive production of the Z(c)(+/-)(3900) hadron by virtual photons has been performed in the channel Z(c)(+/-)(3900). J/Psi pi(+/-). The data cover the range from 7GeV to 19GeV in the centre-of- mass energy of the photon-nucleon system. The full set of the COMPASS data set collected with a muon beam between 2002 and 2011 has been used. An upper limit for the ratio BR(Z(c)(+/-)(3900)-> J/Psi pi(+/-)) x sigma(gamma N) -> Z(c)(+/-)(3900) N/sigma gamma N -> J/Psi N 3.7 x10(-3) has been established at the confidence level of90%. (C) 2015 The Authors. Published by Elsevier B.V.CERN managemen

Odd and even partial waves of eta pi(-) and eta 'pi(-) in pi(-) p -> eta(('))pi(-)p at 191 GeV/c

Exclusive production of eta pi(-) and eta'pi(-) in has been studied with a 191 GeV/c pi(-) beam impinging on a hydrogen target at COMPASS (CERN). Partial-wave analyses reveal different odd/even angular momentum (L) characteristics in the inspected invariant mass range up to 3 GeV/c(2). A striking similarity between the two systems is observed for the L = 2, 4, 6 intensities (scaled by kinematical factors) and the relative phases. The known resonances a(2)(1320) and a(4)(2040) are in line with this similarity. In contrast, a strong enhancement of eta'pi(-) over eta pi(-) is found for the L = 1, 3, 5 waves, which carry non-qq quantum numbers. The L = 1 intensity peaks at 1.7 GeV/c(2) in in and at 1.4 GeV/c(2) in eta pi(-), the corresponding phase motions with respect to L = 2 are different. (C) 2014 The Authors. Published by Elsevier B.V.DFG [1102]; German Bundesministerium fur Bildung und Forschung; Czech Republic MEYS [ME492, LA242]; SAIL (CSR), Govt. of India; CERN-RFBR [08-02-91009, 12-02-91500]; Portuguese FCT - Fundacao para a Ciencia e Tecnologia [CERN/FP/109323/2009, CERN/FP/116376/2010, CERN/FP/123600/2011]; MEXT; JSPS [18002006, 20540299, 18540281]; Daiko Foundation; Yamada Foundation; DFG; EU [283286]; Israel Science Foundation; Polish NCN [DEC-2011/01/M/ST2/02350

Domatic Number of a Graph and its Variants (Extended Abstract)

This chapter presents some numerical invariants of graphs that are related to the concept of domination—namely, the domatic number and its variants.. The word domatic was coined from the words dominating and chromatic in the same way as the word smog was composed from the words smoke and fog. This concept is a certain analogy of the chromatic number, but instead of independent sets, dominating sets are used in its definition. A subset D of the vertex set V(G) of an undirected graphs G is called dominating if for each x V(G) − D there exists a vertex yD adjacent to x. A domatic partition of G is a partition of V(G), all of whose classes are dominating sets in G. The maximum number of classes of a domatic partition of G is called the “domatic number” of G and denoted by d(G). R. Laskar and S. T. Hedetniemi have introduced the connected domatic number d, (G) of a graph G. It is the maximum number of classes of a partition of V(G) into dominating sets that induce connected subgraphs of G.DFG [1102]; German Bundesministerium fur Bildung und Forschung; Czech Republic MEYS [ME492, LA242]; SAIL (CSR), Govt. of India; CERN-RFBR [08-02-91009, 12-02-91500]; Portuguese FCT - Fundacao para a Ciencia e Tecnologia [CERN/FP/109323/2009, CERN/FP/116376/2010, CERN/FP/123600/2011]; MEXT; JSPS [18002006, 20540299, 18540281]; Daiko Foundation; Yamada Foundation; DFG; EU [283286]; Israel Science Foundation; Polish NCN [DEC-2011/01/M/ST2/02350