Wed·Jul 26, 2023Wednesday·July 26, 2023

1. 01*

   Inclusive photon multiplicity at forward pseudorapidities in pp and p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV with ALICE

   Abhi Modak (for the ALICE Collaboration)🇮🇳

   Global observables such as the pseudorapidity distributions of particle multiplicities in the final state are crucial to shed light into the physics processes involved in hadronic collisions. In proton$-$lead (p$-$Pb) collisions at Large Hadron Collider (LHC) energies, such measurements provide an important baseline to understand lead$-$lead (Pb$-$Pb) results by disentangling hot nuclear matter effects from the ones due to the cold nuclear matter. Multiplicity measurements can also put constraints on theoretical models describing the initial stages of the collision, e.g., to what degree the nucleon and the nuclei interact as dilute (partons) or dense (CGC-like) fields. The study of inclusive photon multiplicity aims to provide complementary measurements to those obtained with charged particles. In these proceedings, the pseudorapidity distributions of inclusive photons at forward pseudorapidity ($2.3<{\eta }_{\mathrm{lab}}<3.9$) in pp and p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV are presented. The data samples were collected using the Photon Multiplicity Detector (PMD) of ALICE. The multiplicity dependence of photon production in p$-$Pb collisions is presented and a comparison with charged-particle distributions measured at mid-pseudorapidity is shown. The results are also compared with predictions from Monte Carlo event generators.

   nucl-exSpringer Proc.Phys.(2024)·0 citations
2. 02*

   The Two-Photon Exchange Experiment at DESY

   R. Alarcon🇺🇸 · R. Beck🇩🇪 · J. C. Bernauer🇺🇸 · M. Broering🇺🇸 · A. Christopher🇺🇸 · E. W. Cline🇺🇸 · S. Dhital🇺🇸 · B. Dongwi🇺🇸 · I. Fernando🇺🇸 · M. Finger🇨🇿 · M. Finger Jr.🇨🇿 · I. Friščić🇭🇷 and 28 other authors

   We propose a new measurement of the ratio of positron-proton to electron-proton elastic scattering at DESY. The purpose is to determine the contributions beyond single-photon exchange, which are essential for the Quantum Electrodynamic (QED) description of the most fundamental process in hadronic physics. By utilizing a 20 cm long liquid hydrogen target in conjunction with the extracted beam from the DESY synchrotron, we can achieve an average luminosity of $2.12\times 10^{35}$ cm${}^{-2}\cdot$s${}^{-1}\cdot$sr${}^{-1}$ ($\approx 200$ times the luminosity achieved by OLYMPUS). The proposed TPEX experiment entails a commissioning run at 2 GeV, followed by measurements at 3 GeV, thereby providing new data up to $Q^2=4.6$ (GeV/$c$)${}^2$ (twice the range of current measurements). We present and discuss the proposed experimental setup, run plan, and expectations.

   nucl-exEPJA(2024)·6 citations
3. 03*

   Multi-step particle emission probabilities in superheavy nuclei at moderate excitation energies

   A. Rahmatinejad🇷🇺 · T. M. Shneidman🇷🇺 · G. G. Adamian🇷🇺 · N. V. Antonenko🇷🇺 · P. Jachimowicz🇵🇱 · M. Kowal🇵🇱

   The probabilities of $xn$-, $pxn$-, and $\alpha xn$-evaporation channels in excited superheavy nuclei were evaluated using the Monte Carlo method. The calculations utilized microscopically determined nuclear level densities and were compared with results obtained from the phenomenological Jackson formula. Effective temperatures derived from the microscopic approach were incorporated into the Jackson formula for different evaporation channels at low and moderate excitation energies. Additionally, an analytical formula was introduced to estimate the average kinetic energy of emitted particles in multi-step processes.

   ↳ nucl-thnucl-exPLB(2023)·5 citations
4. 04*

   Lattice QCD study of $\pi \Sigma -\bar{K}N$ scattering and the $\Lambda (1405)$ resonance

   John Bulava🇩🇪 · Bárbara Cid-Mora🇩🇪 · Andrew D. Hanlon🇺🇸 · Ben Hörz🇩🇪 · Daniel Mohler🇩🇪 · Colin Morningstar🇺🇸 · Joseph Moscoso🇺🇸 · Amy Nicholson🇺🇸 · Fernando Romero-López🇺🇸 · Sarah Skinner🇺🇸 · André Walker-Loud🇺🇸

   A lattice QCD computation of the coupled channel $\pi \Sigma -\bar{K}N$ scattering amplitudes in the $\Lambda (1405)$ region is detailed. Results are obtained using a single ensemble of gauge field configurations with $N_{\mathrm{f}}=2+1$ dynamical quark flavors and $m_{\pi }\approx 200$ MeV and $m_K\approx 487$ MeV. Hermitian correlation matrices using both single baryon and meson-baryon interpolating operators for a variety of different total momenta and irreducible representations are used. Several parametrizations of the two-channel scattering $K$-matrix are utilized to obtain the scattering amplitudes from the finite-volume spectrum. The amplitudes, continued to the complex energy plane, exhibit a virtual bound state below the $\pi \Sigma$ threshold and a resonance pole just below the $\bar{K}N$ threshold.

   ↳ hep-lathep-phnucl-exnucl-thPRD(2024)·71 citations
5. 05*

   Optimized nuclear energy density functionals including long-range pion contributions

   L. Zurek🇫🇷 · S. K. Bogner🇺🇸 · R. J. Furnstahl🇺🇸 · R. Navarro Pérez🇺🇸 · N. Schunck🇺🇸 · A. Schwenk🇩🇪

   Nuclear energy density functionals successfully reproduce properties of nuclei across almost the entire nuclear chart. However, nearly all available functionals are phenomenological in nature and lack a rigorous connection to systematically improvable nuclear forces. This issue might be solved with an energy density functional obtained from first principles. As an intermediate step towards this goal we construct the GUDE family of functionals that is obtained from a hybrid scheme consisting of long-range pion-exchange contributions derived from chiral effective field theory at the Hartree-Fock level and a phenomenological Skyrme part. When including pion contributions beyond next-to-leading order in the chiral expansion, we find significant improvements over a reference Skyrme functional constructed following the same protocol. We analyze the importance of different pion contributions and identify which terms drive the observed improvements. Since pions are incorporated without adding further optimization parameters to the functionals, the improvements can be attributed to the functional form of these terms. Our work therefore suggests that the considered chiral contributions constitute useful ingredients for true ab initio energy density functionals.

   ↳ nucl-thnucl-exPRC(2024)·20 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.