Search

We study the inclusive photoproduction of $T_{{\bar c}{\bar c}}(3875)^-$ mesons (which are the antiparticles of the doubly charmed tetraquarks $T_{cc}(3875)^+$ discovered recently by the LHCb Collaboration) from nuclei in the near-threshold energy region within the nuclear spectral function approach by considering incoherent direct (${\gamma}p(n) \to D^+(D^0){T_{{\bar c}{\bar c}}(3875)^-}\Lambda^+_c$) photon--nucleon $T_{{\bar c}{\bar c}}(3875)^-$ creation processes as well as five possible different scenarios for their internal structure with the main goal of clarifying the possibility to decipher this structure (and, hence, that of $T_{cc}(3875)^+$) in photoproduction via integral and differential observables. We calculate the absolute and relative excitation functions for $T_{{\bar c}{\bar c}}(3875)^-$ production off $^{12}$C and $^{184}$W target nuclei at near-threshold photon beam energies of 30--38 GeV, the absolute differential cross sections for their production off these target nuclei at laboratory polar angles of 0$^{\circ}$--10$^{\circ}$ as well as the A and momentum dependences of the relative (transparency ratios) cross sections for $T_{{\bar c}{\bar c}}(3875)^-$ production at photon energy of 35 GeV within the adopted scenarios for the $T_{{\bar c}{\bar c}}(3875)^-$ meson intrinsic structure. We demonstrate that the absolute and relative observables considered show a certain sensitivity to these scenarios. Therefore, the measurement of such observables in future experiments at the proposed high-luminosity electron-ion colliders EIC and EicC in the US and China in the near-threshold energy region might shed light on the $T_{cc}(3875)^+$ internal structure., Comment: 23 pages, 10 figures. arXiv admin note: substantial text overlap with arXiv:2405.01089

We study the production of $X(3872)$ mesons in photon-induced nuclear reactions near the threshold within the collision model based on the nuclear spectral function. The model accounts for direct photon-nucleon $X(3872)$ production processes as well as five different scenarios for their internal structure. We calculate the absolute and relative excitation functions for $X(3872)$ production off $^{12}$C and $^{184}$W target nuclei at near-threshold incident photon energies of 8--16 GeV, the absolute differential cross sections for their production off these target nuclei at laboratory angles of 0$^{\circ}$--10$^{\circ}$ and for incident photon energy of 13 GeV as well as the A dependences of the relative (transparency ratios) cross sections for $X(3872)$ production from ${\gamma}A$ collisions at photon energies around 13 GeV within the adopted scenarios for the $X(3872)$ meson internal structure. We show that the absolute and relative observables considered reveal distinct sensitivity to these scenarios. Therefore, the measurement of such observables in a dedicated experiment at the CEBAF facility in the near-threshold energy range will allow us to get valuable information on the $X(3872)$ inner structure., Comment: 29 pages, 12 figures

We study the near-threshold $\Upsilon(1S)$ meson photoproduction from protons and nuclei by considering incoherent direct non-resonant (${\gamma}p \to {\Upsilon(1S)}p$, ${\gamma}n \to {\Upsilon(1S)}n$) and two-step resonant (${\gamma}p \to P^+_{bi} \to {\Upsilon(1S)}p$, ${\gamma}n \to P^0_{bi} \to {\Upsilon(1S)}n$, $i=1$, 2, 3; $P^{+,0}_{b1}=P^{+,0}_{b}(11080)$, $P^{+,0}_{b2}=P^{+,0}_{b}(11125)$, $P^{+,0}_{b3}=P^{+,0}_{b}(11130)$) bottomonium production processes with the main goal of clarifying the possibility to observe the non-strange hidden-bottom pentaquark states $P^{+,0}_{bi}$ in this production via differential observables. We calculate the absolute excitation functions, energy and momentum distributions for the non-resonant, resonant and for the combined (non-resonant plus resonant) production of $\Upsilon(1S)$ mesons on protons, on carbon and tungsten target nuclei at near-threshold incident photon beam energies by assuming the spin-parity assignments of the hypothetical hidden-bottom resonances $P^{+,0}_{b}(11080)$, $P^{+,0}_{b}(11125)$ and $P^{+,0}_{b}(11130)$ as $J^P=(1/2)^-$, $J^P=(1/2)^-$ and $J^P=(3/2)^-$ within four different realistic choices for the branching ratios of their decays to the ${\Upsilon}(1S)p$ and ${\Upsilon}(1S)n$ modes (0.125, 0.25, 0.5 and 1\%) as well as for two options for the background contribution. We demonstrate that the measurements of these combined observables on proton and nuclear targets in the near-threshold energy region in future experiments at the planned high-luminosity electron-ion colliders EIC and EicC in the US and China should provide evidence for the existence of the above hidden-bottom pentaquark resonances as well as clarify their decay rates., Comment: 33 pages, 13 figures. arXiv admin note: text overlap with arXiv:2211.16037, arXiv:2304.03978; references and some additional comments are added

Accounting for the LHCb observation that the reported hidden-charm strange pentaquark $P_{cs}(4459)^0$ can split into two substructures, $P_{cs}(4455)^0$ and $P_{cs}(4468)^0$, with a mass difference of 13 MeV as well as the newly observed hidden-charm pentaquark resonance $P_{cs}(4338)^0$ with strangeness, we study within the double-peak scenario for the $P_{cs}(4459)^0$ state the near-threshold $J/\psi$ meson production from protons and nuclei by considering incoherent direct non-resonant (${K^-}p \to {J/\psi}\Lambda$) and two-step resonant (${K^-}p \to P_{csi}^0 \to {J/\psi}\Lambda$, $i=1$, 2, 3; $P_{cs1}^{0}=P_{cs}(4338)^0$, $P_{cs2}^{0}=P_{cs}(4455)^0$, $P_{cs3}^{0}=P_{cs}(4468)^0$) charmonium production processes with the main goal of clarifying the possibility to observe within this scenario both above two substructures contributing to the $P_{cs}(4459)^0$ state and the $P_{cs}(4338)^0$ resonance in this production. We calculate the absolute excitation functions, energy and momentum distributions for the non-resonant, resonant and for the combined (non-resonant plus resonant) production of $J/\psi$ mesons on protons as well as on carbon and tungsten target nuclei at near-threshold incident antikaon beam momenta by assuming the spin-parity assignments of the hidden-charm resonances $P_{cs}(4338)^0$, $P_{cs}(4455)^0$ and $P_{cs}(4468)^0$ as $J^P=(1/2)^-$, $J^P=(1/2)^-$ and $J^P=(3/2)^-$ within four different realistic choices for the branching ratios of their decays to the ${J/\psi}\Lambda$ mode (0.125, 0.25, 0.5 and 1\%) as well as for two options for the branching fraction of their decays to the $K^-p$ channel (0.01 and 0.001\%). We show that these combined observables reveal clear sensitivity to these scenarios. Hence, they may be an important tool to provide further evidence for the existence of the above strange hidden-charm pentaquark resonances., Comment: 30 pages, 13 figures; arXiv admin note: text overlap with arXiv:2211.16037, references and some additional comments are added

The near-threshold pion-induced $\phi$ production off nuclei has been studied in the kinematical conditions of the HADES experiment using a collision model based on the nuclear spectral function. Starting from the elementary reaction ${\pi^-}p \to {\phi}n$, absolute differential and integral cross sections for the production of $\phi$ mesons off a light carbon and a heavy tungsten target have been calculated and compared to the recently reported experimental cross sections. The absolute cross section values are shown to be sensitive to the effective nuclear scalar $\phi$ and neutron potentials while the transparency ratio is governed by the ${\phi}N$ absorption cross section. The experimental data are found to be consistent with an attractive ${\phi}$-nucleus potential of $\approx$ -(50--100) MeV at normal nuclear matter density $\rho_0$ and an effective ${\phi}N$ absorption cross section of $\approx$ 12--25 mb. The extracted $\phi$-nucleus potential is deeper than previous theoretical and experimental findings as well as those obtained in the present work within the ($t{\rho}$) approximation with accounting for Pauli correlations from the spin-averaged $\phi$-$p$ scattering length reported in a recent ALICE experiment., Comment: 19 pages, 6 figures, references and some additional comments are added

We study the near-threshold $J/\psi$ meson photoproduction from protons and nuclei by considering incoherent direct non-resonant (${\gamma}p \to {J/\psi}p$, ${\gamma}n \to {J/\psi}n$) and two-step resonant (${\gamma}p \to P_{ci}^+ \to {J/\psi}p$, ${\gamma}n \to P_{ci}^0 \to {J/\psi}n$, $i=1$, 2, 3, 4; $P_{c1}^{+,0}=P_c^{+,0}(4312)$, $P_{c2}^{+,0}=P_c^{+,0}(4337)$, $P_{c3}^{+,0}=P_c^{+,0}(4440)$, $P_{c4}^{+,0}=P_c^{+,0}(4457)$) charmonium production processes. We calculate the absolute excitation functions, energy and momentum distributions for the non-resonant, resonant and for the combined (non-resonant plus resonant) production of $J/\psi$ mesons on protons as well as, using the nuclear spectral function approach, on carbon and tungsten target nuclei at near-threshold incident photon energies by assuming the spin-parity assignments of the hidden-charm resonances $P_{c}^{+,0}(4312)$, $P_{c}^{+,0}(4337)$, $P_{c}^{+,0}(4440)$ and $P_{c}^{+,0}(4457)$ as $J^P=(1/2)^-$, $J^P=(1/2)^-$, $J^P=(1/2)^-$ and $J^P=(3/2)^-$ within three different realistic scenarios for the branching ratios of their decays to the ${J/\psi}p$ and ${J/\psi}n$ modes (0.25, 0.5 and 1%). We show that will be very hard to measure the $P_{ci}^+$ pentaquark states through the scan of the $J/\psi$ total photoproduction cross section on a proton target in the near-threshold energy region around the resonant photon energies of 9.44, 9.554, 10.04 and 10.12 GeV if these branching ratios $\sim$ 1% and less. We also demonstrate that at these photon beam energies the $J/\psi$ energy and momentum combined distributions considered reveal distinct sensitivity to the above scenarios, respectively, at "low" $J/\psi$ total energies and momenta, which implies that they may be an important tool to provide further evidence for the existence of the pentaquark $P_{ci}^+$ and $P_{ci}^0$ resonances., Comment: 26 pages

We study the near-threshold $J/\psi$ meson production on protons and nuclei by considering incoherent direct non-resonant $K^-p \to {J/\psi}\Lambda$ and two-step resonant ${K^-}p \to P_{cs}(4459)^0 \to {J/\psi}\Lambda$ charmonium production processes. We calculate the absolute excitation functions, energy and momentum distributions for the non-resonant, resonant and for the combined (non-resonant plus resonant) production of $J/\psi$ mesons off protons as well as off carbon and tungsten target nuclei at near-threshold incident antikaon energies by considering these elementary production channels as well as by assuming the spin-parity assignment of the hidden-charm resonance $P_{cs}(4459)^0$ with strangeness as $J^P=(3/2)^-$ within six different scenarios for the branching ratio $Br[P_{cs}(4459)^0 \to {J/\psi}\Lambda]$ of the decay $P_{cs}(4459)^0 \to {J/\psi}\Lambda$. We show that the combined observables considered reveal definite sensitivity to these scenarios, which means that they may be an important tool to provide further evidence for the existence of the pentaquark $P_{cs}(4459)^0$ resonance and to get valuable information on its decay rate to the ${J/\psi}\Lambda$ final state. Their measurements could be performed in the future at the J-PARC Hadron Experimental Facility., Comment: 30 pages, 9 figures

We study the near-threshold inclusive photoproduction of $\Xi^-$ hyperons off $^{12}$C and $^{184}$W target nuclei within a first-collision model relying on the nuclear spectral function and including incoherent $\Xi^-$ production in direct elementary ${\gamma}p \to K^+{K^+}\Xi^-$ and ${\gamma}n \to K^+{K^0}\Xi^-$ processes. The model takes into account the impact of the nuclear effective scalar $K^+$, $K^0$, $\Xi^-$ and their Coulomb potentials on these processes as well as the absorption of final $\Xi^-$ hyperons in nuclear matter, the binding of intranuclear nucleons and their Fermi motion. We calculate the absolute differential cross sections and their ratios for the production of $\Xi^-$ hyperons off these nuclei at laboratory polar angles $\le$ 45$^{\circ}$ by photons with energies of 2.5 and 3.0 GeV, with and without imposing the phase space constraints on the $\Xi^-$ emission angle in the respective ${\gamma}p$ center-of-mass system. We also calculate the momentum dependence of the transparency ratio for $\Xi^-$ hyperons for the $^{184}$W/$^{12}$C combination at these photon energies. We show that the $\Xi^-$ momentum distributions (absolute and relative) at the adopted initial photon energies possess, contrary to the transparency ratio for $\Xi^-$ hyperons, a definite sensitivity to the considered changes in the scalar $\Xi^-$ nuclear mean-field potential at saturation density $\rho_0$ in the low-momentum range of 0.1--0.8 GeV/c. Therefore, the precise measurements of these distributions in a dedicated experiment at the CEBAF facility will provide valuable information on the $\Xi^-$ in-medium properties, which will be supplementary to that inferred from studying of the ($K^-$,$K^+$) reactions at initial momenta of 1.6--1.8 GeV/c., Comment: 25 pages, 14 figures

We study the antikaon-induced inclusive cascade $\Xi^-$ hyperon production from $^{12}$C and $^{184}$W target nuclei near threshold within a nuclear spectral function approach. The approach describes incoherent direct $\Xi^-$ hyperon production in elementary ${K^-}p \to {K^+}\Xi^-$ and ${K^-}n \to {K^0}\Xi^-$ processes as well as takes into account the influence of the scalar nuclear $K^-$, $K^+$, $K^0$, $\Xi^-$ and their Coulomb potentials on these processes. We calculate the absolute differential and total cross sections for the production of $\Xi^-$ hyperons off these nuclei at laboratory angles $\le$ 45$^{\circ}$ by $K^-$ mesons with momenta of 1.0 and 1.3 GeV/c, which are close to the threshold momentum (1.05 GeV/c) for $\Xi^-$ hyperon production on the free target nucleon at rest. We also calculate the momentum dependence of the transparency ratio for the $^{184}$W/$^{12}$C combination for $\Xi^-$ hyperons at these $K^-$ beam momenta. We show that the $\Xi^-$ differential and total (absolute and relative) production cross sections at the considered initial momenta reveal a distinct sensitivity to the variations in the scalar $\Xi^-$ nuclear potential at saturation density $\rho_0$, studied in the paper, in the low-momentum region of 0.1--0.6 GeV/c. We also demonstrate that for the subthreshold $K^-$ meson momentum of 1.0 GeV/c there is a strong sensitivity of the transparency ratio for $\Xi^-$ hyperons to the considered changes in the $\Xi^-$ nuclear potential at all outgoing $\Xi^-$ momenta as well. Therefore, the measurement of these absolute and relative observables in a dedicated experiment at the J-PARC will provide valuable information on the $\Xi^-$ in-medium properties, which will be complementary to that deduced from the study of the inclusive ($K^-$,$K^+$) reactions at incident momenta of 1.6--1.8 GeV/c in the $\Xi^-$ bound and quasi-free regions., Comment: 31 pages. arXiv admin note: text overlap with arXiv:2102.00789

We study the inclusive strange axial-vector meson $K_1(1270)^+$ production in ${K^-}A$ reactions at near-threshold laboratory incident antikaon momenta within a nuclear spectral function approach, which describes incoherent direct $K_1(1270)^+$ meson production in $K^-$ meson--proton ${K^-}p \to {K_1(1270)^+}\Xi^-$ production processes and accounts for three different options for its in-medium mass shift (or for its effective scalar potential) at central density $\rho_0$. We calculate the absolute differential and total cross sections for the production of $K_1(1270)^+$ mesons on $^{12}$C and $^{184}$W target nuclei at laboratory angles of 0$^{\circ}$--45$^{\circ}$ by $K^-$ mesons with momenta of 2.5, 2.8 and 3.5 GeV/c, which are close to the threshold momentum ($\approx$ 2.95 GeV/c) for $K_1(1270)^+$ meson production off the free target proton at rest. The intrinsic properties of carbon and tungsten target nuclei have been described in terms of their spectral functions, which take into account the momenta of target protons and the energies of their separation from the considered nuclei. We show that the differential and total (absolute and relative) $K_1(1270)^+$ antikaon-induced production cross sections at initial momenta not far from threshold -- at momenta $\sim$ 2.8--3.5 GeV/c, at which there is yet no strong drop in their strength, reveal a distinct sensitivity to changes in the in-medium shift of the $K_1(1270)^+$ mass, studied in the paper, both in the $K_1(1270)^+$ meson low-momentum (0.1--1.0 GeV/c) and in its full-momentum ranges. This would permit evaluating this shift. Experimental data necessary for this aim can be obtained in a dedicated experiment at the J-PARC Hadron Experimental Facility., Comment: 20 pages. arXiv admin note: substantial text overlap with arXiv:2007.10192

We study the inclusive strange vector meson $K^*(892)^+$ production in ${\pi^-}A$ reactions at near-threshold laboratory incident pion momenta of 1.4--2.0 GeV/c within a nuclear spectral function approach. The approach accounts for incoherent primary $\pi^-$ meson--proton ${\pi^-}p \to {K^*(892)^+}\Sigma^-$ production processes as well as the influence of the scalar $K^*(892)^+$--nucleus potential (or the $K^*(892)^+$ in-medium mass shift) on these processes. We calculate the absolute differential and total cross sections for the production of $K^*(892)^+$ mesons off carbon and tungsten nuclei at laboratory angles of 0$^{\circ}$--45$^{\circ}$ and at these momenta within five scenarios for the above shift. We show that the $K^*(892)^+$ momentum distributions and their excitation functions (absolute and relative) possess a high sensitivity to changes in the in-medium $K^*(892)^+$ mass shift in the low-momentum region of 0.1--0.6 GeV/c. Therefore, the measurement of such observables in a dedicated experiment at the GSI pion beam facility in the near-threshold momentum domain will allow to get valuable information on the $K^*(892)^+$ in-medium properties., Comment: 16 pages, will be published in Chinese Physics C. arXiv admin note: text overlap with arXiv:1910.02755

We study the $\Upsilon(1S)$ meson photoproduction on protons and nuclei at the near-threshold center-of-mass energies below 11.4 GeV (or at the corresponding photon laboratory energies $E_{\gamma}$ below 68.8 GeV). We calculate the absolute excitation functions for the non-resonant and resonant photoproduction of $\Upsilon(1S)$ mesons off protons at incident photon laboratory energies of 63--68 GeV by accounting for direct (${\gamma}p \to {\Upsilon(1S)}p$) and two-step (${\gamma}p \to P^+_b(11080,11125,11130) \to {\Upsilon(1S)}p$) $\Upsilon(1S)$ production channels within different scenarios for the non-resonant total cross section of elementary reaction ${\gamma}p \to {\Upsilon(1S)}p$ and for branching ratios of the decays $P^+_b(11080,11125,11130) \to {\Upsilon(1S)}p$. We also calculate an analogous functions for photoproduction of $\Upsilon(1S)$ mesons on $^{12}$C and $^{208}$Pb target nuclei in the near-threshold center-of-mass beam energy region of 9.0--11.4 GeV by considering respective incoherent direct (${\gamma}N \to {\Upsilon(1S)}N$) and two-step (${\gamma}p \to P^+_b(11080,11125,11130) \to {\Upsilon(1S)}p$, ${\gamma}n \to P^0_b(11080,11125,11130) \to {\Upsilon(1S)}n$) $\Upsilon(1S)$ production processes within a nuclear spectral function approach. We show that a detailed scan of the $\Upsilon(1S)$ total photoproduction cross section on a proton and nuclear targets in the near-threshold energy region in future high-precision experiments at the proposed high-luminosity electron-ion colliders EIC and EicC in the U.S. and China should give a definite result for or against the existence of the non-strange hidden-bottom pentaquark states $P_{bi}^+$ and $P_{bi}^0$ ($i=$1, 2, 3) as well as clarify their decay rates., Comment: 18 pages, Chinese Physics C, accepted for publication, in press. arXiv admin note: text overlap with arXiv:2003.00788

We study the $J/\psi$ photoproduction from nuclei in the near-threshold beam energy region of $E_{\gamma}$=5--11 GeV within the nuclear spectral function approach by considering incoherent direct (${\gamma}N \to {J/\psi}N$) and two-step (${\gamma}p \to P^+_c(4312)$, $P^+_c(4312) \to {J/\psi}p$; ${\gamma}p \to P^+_c(4440)$, $P^+_c(4440) \to {J/\psi}p$; ${\gamma}p \to P^+_c(4457)$, $P^+_c(4457) \to {J/\psi}p$) $J/\psi$ production processes. We calculate the absolute excitation functions for the non-resonant and resonant production of $J/\psi$ mesons off $^{12}$C and $^{208}$Pb target nuclei within the different scenarios for in-medium modification of the directly photoproduced $J/\psi$ mesons and for branching ratios of the decays $P^+_c(4312) \to {J/\psi}p$, $P^+_c(4440) \to {J/\psi}p$ and $P^+_c(4457) \to {J/\psi}p$. We show that the non-resonant subthreshold $J/\psi$ production in ${\gamma}A$ reactions reveals some sensitivity to employed in-medium modification scenarios for $J/\psi$ mesons, which is not masked by the resonantly produced $J/\psi$ mesons, only if above branching ratios are less than 5\%. We also demonstrate that if these branching ratios more than 5\% then the presence of the $P^+_c(4312)$, $P^+_c(4440)$ and $P^+_c(4457)$ resonances in $J/\psi$ photoproduction on nuclei produces above threshold additional enhancements in the behavior of the total $J/\psi$ creation cross section on nuclei, which could be also studied in the future JLab experiments at the CEBAF facility to provide both further evidence for their existence and valuable information on their nature., Comment: 14 pages

We study the pion-induced inclusive $\Lambda(1520)$ hyperon production from nuclei near threshold within a nuclear spectral function approach accounting for incoherent primary $\pi^-$ meson--proton ${\pi^-}p \to K^0\Lambda(1520)$ production processes. We calculate the absolute differential and total cross sections for the production of $\Lambda(1520)$ hyperons off carbon and tungsten nuclei at laboratory angles of 0$^{\circ}$--10$^{\circ}$, 10$^{\circ}$--45$^{\circ}$ and 45$^{\circ}$--85$^{\circ}$ by $\pi^-$ mesons with momentum of 1.7 GeV/c as well as their relative (transparency ratio) differential and integral yields from these nuclei within four scenarios for their total in-medium width. We demonstrate that these absolute observables, contrary to the relative ones, reveal some sensitivity to the $\Lambda(1520)$ in-medium width. Therefore, their measurement in a dedicated experiment at the GSI pion beam facility will allow to shed light on this width., Comment: 14 pages

We study the inclusive near-threshold production of $\eta^\prime$ mesons in $\pi^-$ meson-nucleus reactions on the basis of the first-collision model relying on the nuclear spectral function and including incoherent processes of $\eta^\prime$ production in $\pi^-$ meson--proton collisions. The model accounts for the absorption of initial $\pi^-$ and final $\eta^\prime$ mesons, the binding of intranuclear protons and their Fermi motion, as well as the effect of the scalar $\eta^\prime$--nucleus potential (or the in-medium shift of the $\eta^\prime$ meson mass) on these processes. We calculate the differential and total cross sections for $\eta^\prime$ production off carbon and tungsten nuclei at laboratory angles of 0$^{\circ}$--10$^{\circ}$ and 10$^{\circ}$--45$^{\circ}$ by $\pi^-$ mesons with momentum of 1.7 GeV/c, which is close to the threshold momentum for $\eta^\prime$ creation on a free target proton at rest. We show that the calculated $\eta^\prime$ production cross sections are larger than those, studied earlier in the $\eta^\prime$ photoproduction reactions, by about two orders of magnitude. We also demonstrate that the high absolute values of the present differential and total $\eta^\prime$ production cross sections in the momentum ranges of 0.2--0.3 GeV/c and 0.1--0.6 GeV/c, respectively, possess a high sensitivity to changes in the in-medium shift of the $\eta^\prime$ mass. This offers the possibility of evaluating the above shift at these momenta from the respective data, which could be taken in future experiments at the GSI pion beam facility or at J-PARC., Comment: 12 pages. arXiv admin note: text overlap with arXiv:1806.00303

We study the $J/\psi$ photoproduction from nuclei at near-threshold incident photon energies of 5--11 GeV within the nuclear spectral function approach by considering incoherent direct (${\gamma}N \to {J/\psi}N$) and two-step (${\gamma}p \to P^+_c(4450)$, $P^+_c(4450) \to {J/\psi}p$) photon--nucleon charmonium creation processes. We calculate the absolute and relative excitation functions within the different scenarios for in-medium modification of the directly photoproduced $J/\psi$ mesons. We show that the overall subthreshold $J/\psi$ production in ${\gamma}A$ reactions reveals some sensitivity to adopted in-medium modification scenarios for $J/\psi$ mesons only if branching ratio $Br[P^+_c(4450) \to {J/\psi}p]$ $\sim$ 1% and less. Our studies also demonstrate that the presence of the $P^+_c(4450)$ resonance in $J/\psi$ photoproduction produces above threshold additional enhancements in the behavior of the total $J/\psi$ creation cross section on nuclei, which could be also studied in the future JLab experiments at the upgraded up to 12 GeV CEBAF facility to provide further evidence for its existence., Comment: 13 pages

The production of $\eta^\prime$ mesons in coincidence with forward-going protons has been studied in photon-induced reactions on $^{12}$C and on a liquid hydrogen (LH$_2$) target for incoming photon energies of 1.3-2.6 GeV at the electron accelerator ELSA. The $\eta^\prime$ mesons have been identified via the $\eta^\prime\rightarrow \pi^0 \pi^0\eta \rightarrow 6 \gamma$ decay registered with the CBELSA/TAPS detector system. Coincident protons have been identified in the MiniTAPS BaF$_2$ array at polar angles of $2^{\circ} \le \theta _{p} \le 11^{\circ}$. Under these kinematic constraints the $\eta^\prime$ mesons are produced with relatively low kinetic energy ($\approx$ 150 MeV) since the coincident protons take over most of the momentum of the incident-photon beam. For the C-target this allows the determination of the real part of the $\eta^\prime$-carbon potential at low meson momenta by comparing with collision model calculations of the $\eta^\prime$ kinetic energy distribution and excitation function. Fitting the latter data for $\eta^\prime$ mesons going backwards in the center-of-mass system yields a potential depth of V = $-$(44 $\pm$ 16(stat)$\pm$15(syst)) MeV, consistent with earlier determinations of the potential depth in inclusive measurements for average $\eta^\prime$ momenta of $\approx$ 1.1 GeV/$c$. Within the experimental uncertainties, there is no indication of a momentum dependence of the $\eta^\prime$-carbon potential. The LH$_2$ data, taken as a reference to check the data analysis and the model calculations, provide differential and integral cross sections in good agreement with previous results for $\eta^\prime$ photoproduction off the free proton., Comment: 9 pages, 13 figures. arXiv admin note: text overlap with arXiv:1608.06074

We study the near-threshold pion-induced production of $\phi$ mesons off nuclei in the kinematical conditions of the HADES experiment, recently performed at GSI. The calculations have been performed within a collision model based on the nuclear spectral function. The model accounts for both the primary $\pi^-$ meson--proton ${\pi^-}p \to {\phi}n$ and the secondary pion--nucleon ${\pi}N \to {\phi}N$ $\phi$ production processes as well as the effects of the nuclear $\phi$ and nucleon mean-field potentials. We find that the primary reaction channel ${\pi^-}p \to {\phi}n$ dominates in the $\phi$ production off $^{12}$C and $^{184}$W target nuclei in the HADES acceptance window at incident pion momentum of 1.7 GeV/c. We calculate the momentum dependence of the absolute and relative (transparency ratio) $\phi$ meson yields from the above direct channel. The calculations have been performed for this initial pion momentum allowing for different options for the ${\phi}N$ absorption cross section $\sigma_{{\phi}N}$ and different scenarios for the in-medium mass shifts of the $\phi$ meson and secondary neutron, produced together with $\phi$ in this channel. We demonstrate that the transparency ratio for the $\phi$ mesons has, contrary to the absolute cross sections, an insignificant sensitivity to the $\phi$ meson and secondary neutron in-medium mass shifts at $\phi$ momenta studied in the HADES experiment. On the other hand, we show that there are measurable changes in the transparency ratio due to the ${\phi}N$ absorption cross section, which means that such relative observable can be useful to help determine this cross section from the data taken in the HADES experiment., Comment: 21 pages, 9 figures

Recent experiments studying the meson-nucleus interaction to extract meson-nucleus potentials are reviewed. The real part of the potentials quantifies whether the interaction is attractive or repulsive while the imaginary part describes the meson absorption in nuclei. The review is focused on mesons which are sufficiently long-lived to potentially form meson-nucleus quasi-bound states. The presentation is confined to meson production off nuclei in photon-, pion-, proton-, and light-ion induced reactions and heavy-ion collisions at energies near the production threshold. Tools to extract the potential parameters are presented. In most cases, the real part of the potential is determined by comparing measured meson momentum distributions or excitation functions with collision model or transport model calculations. The imaginary part is extracted from transparency ratio measurements. Results on $K^+, K^0, K^-, \eta, \eta^\prime, \omega$, and $\phi$ mesons are presented and compared with theoretical predictions. The interaction of $K^+$ and $K^0$ mesons with nuclei is found to be weakly repulsive, while the $K^-, \eta,\eta^\prime, \omega$ and $\phi$ meson-nucleus potentials are attractive, however, with widely different strengths. Because of meson absorption in the nuclear medium the imaginary parts of the meson-nucleus potentials are all negative, again with a large spread. An outlook on planned experiments in the charm sector is given. In view of the determined potential parameters, the criteria and chances for experimentally observing meson-nucleus quasi-bound states are discussed. The most promising candidates appear to be the $\eta$ and $\eta^\prime$ mesons., Comment: 86 pages, 67 figures

We study ${\Lambda}K^+$ pair production in the interaction of protons of 2.83 GeV kinetic energy with C, Cu, Ag, and Au target nuclei in the framework of the nuclear spectral function approach for incoherent primary proton--nucleon and secondary pion--nucleon production processes, and processes associated with the creation of intermediate ${\Sigma^0}K^+$ pairs. The approach accounts for the initial proton and final $\Lambda$ hyperon absorption, final $K^+$ meson distortion in nuclei, target nucleon binding, and Fermi motion, as well as nuclear mean-field potential effects on these processes. We calculate the $\Lambda$ momentum dependence of the absolute ${\Lambda}K^+$ yield from the target nuclei considered, in the kinematical conditions of the ANKE experiment, performed at COSY, within the different scenarios for the $\Lambda$-nucleus effective scalar potential. We show that the above observable is appreciably sensitive to this potential in the low-momentum region. Therefore, direct comparison of the results of our calculations with the data from the ANKE-at-COSY experiment can help to determine the above potential at finite momenta. We also demonstrate that the two-step pion--nucleon production channels dominate in the low-momentum ${\Lambda}K^+$ production in the chosen kinematics and, therefore, they have to be taken into account in the analysis of these data., Comment: 29 pages

The excitation function and momentum distribution of {\eta}' mesons have been measured in photoproduction off 93^Nb in the energy range of 1.2-2.9 GeV. The experiment has been performed with the combined Crystal Barrel and MiniTAPS detector system, using tagged photon beams from the ELSA electron accelerator. Information on the sign and magnitude of the real part of the {\eta}'-Nb potential has been extracted from a comparison of the data with model calculations. An attractive potential of -(41 \pm 10(stat) \pm 15(syst)) MeV depth at normal nuclear matter density is deduced within model uncertainties. This value is consistent with the potential depth of -(37 \pm 10(stat) \pm 10(syst)) MeV obtained in an earlier measurement for a light nucleus (carbon). This relatively shallow {\eta}'-nucleus potential will make the search for {\eta}'-nucleus bound states more difficult., Comment: 9 pages, 6 figures

We study the $J/\psi$ photoproduction from nuclei near the kinematic threshold within the first collision model, based on the nuclear spectral function, for incoherent primary photon--nucleon charmonium creation processes. The model takes into account the final $J/\psi$ absorption, target nucleon binding and Fermi motion, the formation length of $J/\psi$ mesons as well as the effect of their nuclear mean-field potential on these processes. We calculate the A dependences of the absolute and relative (transparency ratio) charmonium yields as well as its absolute and relative excitation functions within the different scenarios for the $J/\psi N$ absorption cross section, for the $J/\psi$ formation length and for $J/\psi$ in-medium modification. We demonstrate that the studied observables, on the one hand, are not practically affected by the charmonium formation length and mass shift effects and, on the other hand, they are appreciably sensitive to the genuine $J/\psi N$ absorption cross section at above threshold beam energies, which means that these observables can be useful to help determine the $J/\psi N$ absorption cross section from the comparison of the results of our calculations with the future data from the experiments in the Hall C at the upgraded up to 12 GeV CEBAF facility. We also show that the absolute and relative excitation functions for $J/\psi$ subthreshold production in ${\gamma}A$ reactions reveal some sensitivity to adopted in-medium modification scenarios for $J/\psi$ mesons. Therefore, such observables, measured in the subthreshold energy domain, may be an important tool to get valuable information on the charmonium in-medium properties in cold nuclear matter., Comment: 16 pages. arXiv admin note: substantial text overlap with arXiv:1409.2428

The production of non-phi K+K- pairs by protons of 2.83 GeV kinetic energy on C, Cu, Ag, and Au targets has been investigated using the COSY-ANKE magnetic spectrometer. The K- momentum dependence of the differential cross section has been measured at small angles over the 0.2--0.9 GeV/c range. The comparison of the data with detailed model calculations indicates an attractive K- -nucleus potential of about -60 MeV at normal nuclear matter density at a mean momentum of 0.5 GeV/c. However, this approach has difficulty in reproducing the smallness of the observed cross sections at low K- momenta., Comment: 7 pages, 5 figures, 1 table

We study the non-resonant (non-$\phi$) production of $K^+K^-$ pairs by protons of 2.83 GeV kinetic energy on C, Cu, Ag, and Au targets within the collision model, based on the nuclear spectral function, for incoherent primary proton--nucleon and secondary pion--nucleon creation processes. The model takes into account the initial proton and final kaon absorption, target nucleon binding and Fermi motion as well as nuclear mean-field potential effects on these processes. We calculate the antikaon momentum dependences of the exclusive absolute and relative $K^+K^-$ pair yields in the acceptance window of the ANKE magnetic spectrometer, used in a recent experiment performed at COSY, within the different scenarios for the antikaon-nucleus optical potential. We demonstrate that the above observables are strongly sensitive to this potential. Therefore, they can be useful to help determine the $K^-$ optical potential from the direct comparison of the results of our calculations with the data from the respective ANKE-at-COSY experiment. We also show that the pion--nucleon production channels dominate in the low-momentum $K^-$, $K^+$ production in the considered kinematics and, hence, they have to be accounted for in the analysis of these data., Comment: 19 pages

We study the near-threshold photoproduction of $\eta^\prime$ mesons from nuclei in coincidence with forward going protons in the kinematical conditions of the Crystal Barrel/TAPS experiment, recently performed at ELSA. The calculations have been performed within a collision model based on the nuclear spectral function. The model accounts for both the primary ${\gamma}p \to {\eta^\prime}p$ process and the two-step intermediate nucleon rescattering processes as well as the effect of the nuclear $\eta^\prime$ mean-field potential. We calculate the exclusive $\eta^\prime$ kinetic energy distributions for the $^{12}$C($\gamma$, ${\eta^\prime}p$) reaction for different scenarios of $\eta^\prime$ in-medium modification. We find that the considered two-step rescattering mechanism plays an insignificant role in ${\eta^\prime}p$ photoproduction off the carbon target. We also demonstrate that the calculated $\eta^\prime$ kinetic energy distributions in primary photon--proton ${\eta^\prime}p$ production reveal strong sensitivity to the depth of the real ${\eta^\prime}$ potential at normal nuclear matter density (or to the ${\eta^\prime}$ in-medium mass shift) in the studied incident photon energy regime. Therefore, such observables may be useful to help determine the above ${\eta^\prime}$ in-medium renormalization from the comparison of the results of our calculations with the data from the CBELSA/TAPS experiment. In addition, we show that these distributions are also strongly influenced by the momentum-dependent optical potential, which the outgoing participant proton feels inside the carbon nucleus. This potential should be taken into account in the analysis of these data with the aim to obtain information on the ${\eta^\prime}$ modification in cold nuclear matter., Comment: 17 pages

We study the J/Psi production from nuclei near the kinematic threshold within the collision model, based on the nuclear spectral function, for incoherent primary proton-nucleon charmonium creation processes. The model takes into account the initial proton and final J/Psi absorption, target nucleon binding and Fermi motion, the formation length of J/Psi mesons as well as the effect of their nuclear mean-field potential on these processes. We calculate the A dependences of the absolute and relative (transparency ratio) charmonium yields as well as its excitation function within the different scenarios for the J/PsiN absorption cross section, for the J/Psi formation length and for J/Psi in-medium modification. We demonstrate that the former observables, on the one hand, are not practically affected by the charmonium formation length effects and, on the other hand, they are appreciably sensitive to the genuine J/PsiN absorption cross section at beam energies of interest, which means that these observables can be useful to help determine the above cross section from the comparison of the results of our calculations with the future data from the CBM experiment at FAIR-the upcoming accelerator facility at GSI-Darmstadt, Germany. We also show that the excitation function for J/Psi subthreshold production in pA reactions reveals some sensitivity to adopted its in-medium modification scenarios. Therefore, such observable may be an important tool to get valuable information on the charmonium in-medium properties., Comment: 10 pages, 4 figures