Inclusive production of non-strange resonances inK − p interactions at 32 GeV/c

New data on the inclusive production of the non-strange resonances ?⁰(770), ω(783), ?(1020) andf(1270) inK ^? p interactions at 32 GeV/c are presented. The inclusive production cross sections are equal to (4.32±0.72) mb, (3.7±1.4) mb, (0.65±0.10) mb and (0.91±0.35) mb respectively. Estimates of the topological cross sections are also obtained. The invariant and non-invariantx-distributions for the vector mesons ?⁰ and ? indicate the prevalence of forward resonance production in the c.m. system. For the tensorf-meson the rapidity andx-distributions are presented. Thet′-distributions for ?⁰, ?, andf have exponential slopes of 0.6±0.1 GeV^?2, 1.2±0.2 GeV^?2, and 0.8±0.5 GeV^?2 respectively. The exponential slope ofp _T ² -distribution of thef-meson is equal to (2.3±0.5) GeV^?2.     

Summary of the CMS potential for the Higgs boson discovery

The European Physical Journal C - This work summarizes the studies for the Higgs boson searches in CMS at the LHC collider. The main discovery channels are presented and the potential is given for...     

Inclusive single and double diffractive dissociations inK + p interactions at 32 GeV/c

We study single and double inclusive diffractive production in a 32 GeV/c K ⁺ p experiment in MIRABELLE at the Serpukhov accelerator. From reactionsK ⁺ p→K ⁺+X ⁺ andK ⁺ p→X ⁺+p we determine the total proton and kaon single diffractive dissociation cross sections \(\sigma (p\xrightarrow{{K^ + }}p_D ) = 0.90 \pm 0.12 mb\) and \(\sigma (K^ + \xrightarrow{p}K_D^ + ) = 0\) . 90±0.17 mb, respectively. In either case the only notable contributions come from dissociations into 1 and 3 charged particles. Kaon dissociation exhibits a pronounced slope-mass correlation. The search for double diffractive production in reactionsK ⁺ p→(K ⁺π^?π⁺)+X ⁺ andK ⁺ p→(pπ ⁺ π ^?)+X ⁺ leads in either case to an estimated total double diffractive cross section σ(K ⁺p→K _D ⁺ p_D) of ?220 μb. The double dissociation differential cross section exhibits a large slope of ?10GeV^?2 in the nearthreshold mass region, rapidly decreasing to ?4 GeV^?2 with increasing excitation mass. At our c.m. energy \((\sqrt s \simeq 8 GeV)\) the ratio σ_{inel dif}/σ_el is 0.85±0.10, the total diffractive cross section σ_dif≡σ_el+σ_{inel dif}=4.41±0.24 mb and the fraction σ_dif(K ⁺ p)/σ_tot(K ⁺ p) is 25±2%. TheK ⁺ andK ^? diffractive excitation mass spectra, differential cross sections and total diffractive cross sections are very similar for both single and double dissociations.     

Kinetics of the solvolyses of benzhydryl derivatives: basis for the construction of a comprehensive nucleofugality scale

A series of 21 benzhydrylium ions (diarylmethylium ions) are proposed as reference electrofuges for the development of a general nucleofugality scale, where nucleofugality refers to a combination of leaving group and solvent. A total of 167 solvolysis rate constants of benzhydrylium tosylates, bromides, chlorides, trifluoroacetates, 3,5-dinitrobenzoates, and 4-nitrobenzoates, two-thirds of which have been determined during this work, were subjected to a least-squares fit according to the correlation equation log k(25 degrees C) = sf(Nf + Ef), where sf and Nf are nucleofuge-specific parameters and Ef is an electrofuge-specific parameter. Although nucleofuges and electrofuges characterized in this way cover more than 12 orders of magnitude, a single set of the parameters, namely sf, Nf, and Ef, is sufficient to calculate the solvolysis rate constants at 25 degrees C with an accuracy of +/-16 %. Because sf approximately 1 for all nucleofuges, that is, leaving group/solvent combinations, studied so far, qualitative discussions of nucleofugality can be based on Nf.     

Two-particle production inK + p interactions at 32 GeV/c

Results are presented on two-particle inclusive production inK ⁺ p interactions at 32 GeV/c. We study thex _1,2=x ₁+x ₂ dependence of invariant structure functions of (ππ)-pairs and compare them to single particle inclusive distributions in the fragmentation regions. Distributions of particles observed at Feynmanx ₂ in association with various “trigger” particles or systems atx ₁ in the same hemisphere are dicussed in terms of the reduced variable \(\tilde x_2 = x_2 /(1 - |x_1 |)\) . We further present absolute production rates and production ratios of π⁺'s and π^?'s associated with π^±,K _s ⁰ , Λ, \(\bar \Lambda \) ,K ^*+ (890), (K _s ⁰ π⁺), and (π⁺ π^?)-triggers, and compare them with qualitative predictions of the quark recombination model. Forwardbackward correlations between (K _s ⁰ π^±), (K _s ⁰ ,p), (Λ, π^?), \((\bar \Lambda \pi ^ \pm )\) , and (p, π^?) pairs are also discussed.     

K + p andK − p elastic scattering at 32.1 GeV/c

Results are presented onK ⁺ p andK ^? p elastic scattering at 32.1 GeV/c in the |t| interval 0.06–1.4 GeV². The samples contain approximately 15,000 events each and are obtained in the MIRABELLE bubble chamber at the Serpukhov accelerator. The |t| distributions are parametrized by quadratic exponential formsdσ/dt=A exp (bt+ct ²). The total elastic cross sections, obtained by integrating the fitted distributions, are (2.39±0.07) mb and (2.57±0.10) mb inK ⁺ p andK ^? p interactions, respectively. A cross-over between theK ⁺ p andK ^? p differential cross sections is found at |t _c |=0.17±0.02 GeV². The hypothesis of geometric scaling becomes valid somewhere between 32 and 70 GeV/c forK ⁺ p interactions, and is trivially verified forK ^? p scattering. Finally, an impact parameter analysis of the difference betweenK ^? p andK ⁺ p elastic amplitudes is presented.     

Evidence for double dissociation in K-p interactions at 14.3 GeV/c

We have studied the reaction K^-p → K^-π⁺π^-π⁺π^-p at 14.3 GeV/c to search for evidence of the double dissociation process $\text{K}{}^{\mathrm{-}}\text{p}\text{→}\text{QN}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}^1$. In the channel $\text{K}{}^{\mathrm{-}}\text{p}\text{→}\text{K}{}^{10}\text{(890)}$π₁^-π₂^-Δ⁺⁺ (1236) there is evidence for simultaneous production of low-mass enhancements in the $\text{K}{}^{10}\text{π}{}_1{}^{\mathrm{-}}$ and Δ⁺⁺(1236)π₂^- subsystems which correspond to the $\text{Q}\text{→}\text{K}{}^1\text{(890)π}$ and $\text{N}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}^1\text{→ Δπ}$ decay modes. In this particular final state the double fragmentation system is produced with a cross section of the order of a few microbarns. Our data are consistent with the factorizable pomeron exchange model of double diffractive dissociation.     

Exclusive reactions in pp interactions at 32 GeV/c

The cross sections of several exclusive reactions in $\text{p}\text{p}$ interactions are given. In the channels $\text{p}\text{p}\text{→}\text{p}\text{p}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{and}\text{p}\text{p}\text{→}\text{p}\text{p}\text{2π}{}^{\mathrm{+}}\text{2π}{}^{\mathrm{?}}$ which dominate the interactions, the single and double diffractive dissociations are analysed and compared to the results obtained with K^±p interactions at the same energy, pp and $\text{p}\text{p}$ interactions at other energies. The test of factorization at the p → pπ⁺π^? vertex is well verified. The process $\text{p}\text{p}\text{→ Δ}{}^{\mathrm{++}}\text{Δ}{}^{\mathrm{++}}$ is studied and the cross sections of $\text{Δ}{}^{\mathrm{++}}\text{,}\text{Δ}{}^{\mathrm{++}}\text{, ?}{}^0\text{and}\text{f}{}^0$ production are also given.     

Nucleofugality of phenyl and methyl carbonates

A series of X,Y-substituted benzhydryl phenyl carbonates 1 and X,Y-substituted benzhydryl methyl carbonates 2 were subjected to solvolysis in different methanol/water, ethanol/water, and acetone/water mixtures at 25 degrees C. The LFER equation, log k = sf(Ef + Nf), was used to derive the nucleofuge-specific parameters (Nf and sf) for phenyl carbonate (1LG) and methyl carbonate (2LG) leaving groups in a given solvent in SN1 type reaction. Kinetic measurements showed that phenyl carbonates solvolyze one order of magnitude faster than methyl carbonates. Optimized geometries of 1LG and 2LG at B3LYP/6-311G(d,p), B3LYP/6-311++G(d,p), and MP2(full)/6-311++G(d,p) levels revealed that negative charge delocalization in carbonate anions to all three oxygen atoms occurs due to negative hyperconjugation. Phenyl carbonate (1LG) is a better leaving group (Nf = -0.84 +/- 0.07 in 80% v/v aq EtOH) than methyl carbonate 2LG (Nf = -1.84 +/- 0.07 in 80% v/v aq EtOH) because of more pronounced negative hyperconjugation, which is characterized with a more elongated RO-C bond and more increased RO-C-CO angle in 1LG than in 2LG. Calculated affinities of benzhydryl cation toward methyl and phenyl carbonate anions (DeltaDeltaEaff = 11.7 kcal/mol at the B3LYP/6-311++G(d,p) level and DeltaDeltaEaff = 2.7 kcal/mol at the PCM-B3LYP/6-311++G(d,p) level in methanol, respectively) showed that 1LG is more stabilized than 2LG, which is in accordance with greater solvolytic reactivity of 1 than 2.