scholarly journals Pion exchange interaction in the γp → pe+e− reaction

2018 ◽  
Vol 27 (07) ◽  
pp. 1850057 ◽  
Author(s):  
Swapan Das
Keyword(s):  
Vector Meson ◽  
Exchange Interaction ◽  
Invariant Mass ◽  
Mass Distribution ◽  
Cross Sections ◽  
Differential Cross ◽  
Energy Region ◽  
Invariant Mass Distribution ◽  
Pion Exchange ◽  
Vector Meson Dominance

The [Formula: see text] interference has been studied in the dilepton invariant mass distribution spectra in the photonuclear reaction, but that is not done for the gamma-nucleon reaction. In the recent past, the [Formula: see text] invariant mass distribution spectrum in the [Formula: see text] reaction, i.e., [Formula: see text] reaction, was measured at Jefferson Laboratory to look for the [Formula: see text] interference in the multi-GeV region. To study the mechanism of this reaction, the differential cross section of the [Formula: see text] invariant mass distribution is calculated in the quoted energy region. The reaction is assumed to proceed as [Formula: see text]; [Formula: see text], where [Formula: see text] denotes a vector meson, i.e., either [Formula: see text] or [Formula: see text] meson. The photoproduction of the vector meson is described by the Vector Meson Dominance (VMD) model which consists of diagonal and off-diagonal processes. The diagonal process is described as [Formula: see text]. The low-energy [Formula: see text] meson photoproduction data is well described by the off-diagonal process which is illustrated as [Formula: see text]. The reaction [Formula: see text] proceeds due to one pion exchange interaction. The differential cross-sections of the [Formula: see text] reaction due to the above processes of VMD model are compared, and the significance of the pion exchange interaction is investigated in the energy region of [Formula: see text] beam available at Jefferson Laboratory.

scholarly journals MEASUREMENT OF EXCITED HYPERONS IN PHOTOPRODUCTION AT CLAS

2014 ◽  
Vol 26 ◽  
pp. 1460084
Author(s):  
◽  
KEI MORIYA ◽  
REINHARD A. SCHUMACHER
Keyword(s):  
Invariant Mass ◽  
Mass Distribution ◽  
Cross Sections ◽  
Invariant Mass Distribution ◽  
Total Cross Sections ◽  
Future Studies ◽  
Jefferson Lab ◽  
Measurement Results

Measurement results of photoproduced excited hyperon states using the CLAS detector at Jefferson Lab are shown. The invariant mass distribution of the Λ(1405) has recently been shown to be different for each of the three Σπ channels that it decays to, showing that there is prominent interference between the isospin I = 0 and I = 1 isospin amplitudes. Measurements of the differential and total cross sections of the three hyperons Λ(1405), Σ0(1385), and Λ(1520) are presented and compared. Prospects of future studies using a 12 GeV beam with the GlueX detector are briefly given.

THE pp → ppπ0π0 REACTION AND ITS LIMITING CASE, FUSION TO QUASI-BOUND 2He, IN SEARCH OF THE ABC EFFECT

2011 ◽  
Vol 26 (03n04) ◽  
pp. 702-704
Author(s):  
◽  
T. SKORODKO ◽  
M. BASHKANOV ◽  
D. BOGOSLOWSKY ◽  
H. CALÉN ◽  
...  
Keyword(s):  
Invariant Mass ◽  
Mass Distribution ◽  
Invariant Mass Distribution ◽  
Pion Exchange ◽  
Pp Collisions ◽  
Excitation Process ◽  
Low Mass ◽  
Limiting Case ◽  
Mass Enhancement

The π0π0 production in pp -collisions has been investigated in exclusive and kinematically complete measurements from threshold up to Tp = 1.4 GeV . For incident energies Tp > 1 GeV , i.e. in the region beyond the Roper excitation, the ΔΔ excitation process takes over. The data are well explained by the t-channel ΔΔ process dominated by pion exchange. There is no low-mass enhancement (ABC effect) in the π0π0-invariant mass distribution beyond that given by the conventional t-channel ΔΔ process. This is also true for the limiting case, where the protons are in the quasi-bound 2 He state.

scholarly journals QED corrections in $$ \overline{B}\to \overline{K}{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{-} $$ at the double-differential level

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Gino Isidori ◽  
Saad Nabeebaccus ◽  
Roman Zwicky
Keyword(s):  
Phase Space ◽  
Detailed Analysis ◽  
Invariant Mass ◽  
Mass Distribution ◽  
Invariant Mass Distribution ◽  
Semileptonic Decays ◽  
Lepton Pair ◽  
Specific Choice ◽  
Slicing Method

Abstract We present a detailed analysis of QED corrections to $$ \overline{B}\to \overline{K}{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{-} $$ B ¯ → K ¯ ℓ + ℓ − decays at the double-differential level. Cancellations of soft and collinear divergences are demonstrated analytically using the phase space slicing method. Whereas soft divergences are found to cancel at the differential level, the cancellation of the hard-collinear logs ln mℓ require, besides photon-inclusiveness, a specific choice of kinematic variables. In particular, hard-collinear logs in the lepton-pair invariant mass distribution (q2), are sizeable and need to be treated with care when comparing with experiment. Virtual and real amplitudes are evaluated using an effective mesonic Lagrangian. Crucially, we show that going beyond this approximation does not introduce any further infrared sensitive terms. All analytic computations are performed for generic charges and are therefore adaptable to semileptonic decays such as $$ \overline{B}\to D\mathrm{\ell}\overline{\nu } $$ B ¯ → D ℓ ν ¯ .

scholarly journals Invariant-mass distribution of top-quark pairs and top-quark mass determination

2020 ◽  
Vol 44 (9) ◽  
pp. 091001
Author(s):  
Wan-Li Ju ◽  
Guoxing Wang ◽  
Xing Wang ◽  
Xiaofeng Xu ◽  
Yongqi Xu ◽  
...  
Keyword(s):  
Invariant Mass ◽  
Mass Distribution ◽  
Top Quark ◽  
Quark Mass ◽  
Invariant Mass Distribution ◽  
Mass Determination ◽  
Top Quark Mass ◽  
Quark Pairs ◽  
Top Quark Pairs

scholarly journals Role of N*(1535) in the Λ+c → K0ηp decay and the possible фp state in the Λ+c → π0фp decay

2020 ◽  
Vol 241 ◽  
pp. 02010
Author(s):  
Ju-Jun Xie ◽  
Li-Sheng Geng ◽  
Feng-Kun Guo
Keyword(s):  
Invariant Mass ◽  
Mass Distribution ◽  
Final State Interaction ◽  
Invariant Mass Distribution ◽  
Lagrangian Model ◽  
Final State ◽  
Peak Structure ◽  
Effective Lagrangian ◽  
Unitary Approach ◽  
Chiral Unitary Approach

The nonleptonic weak decays of Λ+c → K0ηp and Λ+c → π0фp are investigated from the viewpoint of probing the N*(1535) resonance and the possible фp state. For the Λ+c → K0ηp decay, we study the invariant mass distribution of ηp with both the chiral unitary approach and an effective Lagrangian model. Within the chiral unitary approach, the N*(1535) resonance is dynamically generated from the final state interaction of mesons and baryons in coupled channels. While for the effective Lagrangian model, we take a Breit-Wigner formula for the N*(1535) resonance. We found that the behavior of the N*(1535) resonance in the Λ+c → K0N*(1535) → K0ηp decay within the two approaches is different. For the Λ+c → π0фp decay, we consider a triangle singularity mechanism, where the Λ+c decays into the K*Σ*(1385), the Σ*(1385) decays into the π0Σ/Λ, and then the K*Σ/Λ merge to produce the фp in the final state. This mechanism produces a peak structure around 2020 MeV. In addition, the possibility that there is a hidden-strange pentaquark-like state is also considered by taking into account the final state interactions of K*Λ, K*Σ, and фp. We conclude that it is difficult to search for the hidden-strange state in this decay. However, we do expect nontrivial behavior in the фp invariant mass distribution. The proposed Λ+c decay mechanism here can provide valuable information on the properties of these nuclear resonances and can in principle be tested by experiments such as BESIII, LHCb and Belle-II.

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