119028691
In-medium modification of P-wave charmonia from QCD sum rules
We investigate the changes of the masses and widths of {chi}{sub c0} and {chi}{sub c1} in hot gluonic matter near T{sub c} and in a nuclear medium using QCD sum rules. As in the previous works for the J/{psi} and {eta}{sub c}, in-medium effects are incorporated through the changes of gluon condensates. Twist-2 terms for the {sup 3}P{sub 0}({chi}{sub c0}) and {sup 3}P{sub 1}({chi}{sub c1}) are also included for the first time. The results show that larger mass shifts and width broadenings take place as compared to the S-wave states. As the critical change take place near T{sub c}, related measurements can reveal critical phenomenon in QCD.
7806265
Meson exchange effect on color superconductivity
We investigate the effects of pion and gluon exchanges on the formation of two-flavor color superconductivity at moderate density, � < 1GeV . The chiral quark model proposed by Manohar and Georgi containing pions as well as gluons is employed to show that the pion exchange reduces substantially the value of the superconducting gap gotten with the gluon exchange only. It turns out that the pion exchanges produce a repulsion between quark-quark pair in a spin and isospin singlet state. We suggest that the phase consisiting of pions, gluons and quarks is one of the candidates of in-medium QCD phase at moderate density.
117217556
Hen Process in Effective Field Theory
An effective field theory technique that combines the standard nuclear physics approach and chiral perturbation theory is applied to the $hen$ process, ${}^{3}{He}+n\to {}^{4}{He}+ \gamma$. For the initial and final nuclear states, high-precision wave functions are generated via the variational Monte Carlo method using the Argonne $v_{14}$ potential and Urbana VIII trinucleon interactions, while the relevant transition operators are calculated up to ${\cal O}(Q^4)$ in HB$\chi$PT. The imposition of the renormalization condition that the magnetic moments of ${}^{3}{He}$ and ${}^{3}{H}$ be reproduced allows us to carry out a parameter-free calculation of the $hen$ cross section. The result, $\sigma=(60\pm 3\pm 1) \mu b$, is in reasonable agreement with the experimental values, $(54\pm 6) \mu b$ and $(55\pm 3) \mu b$. This agreement demonstrates the validity of the calculational method previously used for estimating the reaction rate of the solar $hep$ process.
119215813
Symmetry violations in few-body reactions: old and new approaches
Abstract As an attempt to find a way to resolve the discrepancy between calculated by traditional methods PV e_ects and the available set of experimental data, we analyze the methods of calculations of symmetry violating e_ects in fewbody nuclear systems. The overview of methods of calculations of PV and TRIV e_ects in few-body neutron induced reactions is presented with the analysis of values of calculated parameters and their accuracy.
15149403
Notes from the Underground: A Propos of Givental's Conjecture
These brief notes record our puzzles and findings surrounding Givental's recent conjecture which expresses higher genus Gromov-Witten invariants in terms of the genus-0 data. We limit our considerations to the case of a projective line, whose Gromov-Witten invariants are well-known and easy to compute. We make some simple checks supporting his conjecture.
119118388
Higher twist contribution to fragmentation function in inclusive hadron production in e^+e^- annihilation
We apply collinear expansion to inclusive hadron production in $e^+e^-$ annihilation and derive a formalism suitable for systematic study of leading as well as higher twist contributions to fragmentation functions at the tree level. We make the calculations for hadrons with spin-0, spin-1/2 as well as spin-1 and obtain the results in terms of different components of fragmentation functions for the hadronic tensors, the differential cross section as well as hadron polarizations in different cases. The results show a number of interesting features such as the existence of transverse polarization for spin-1/2 hadrons at the twist-3 level, the quark polarization independence of the spin alignment of vector mesons.