Fri·Mar 13, 2020Friday·March 13, 2020

1. 01*

   Overview of light nuclei production in relativistic heavy-ion collisions

   D. Oliinychenko🇺🇸

   We briefly overview motivations, some recent results and challenges in studying light nuclei production in relativistic heavy ion collisions.

   hep-phNPA(2021)·40 citations
2. 02*

   Lorentz and permutation invariants of particles I

   Ben Gripaios · Ward Haddadin · Christopher G. Lester

   A theorem of Weyl tells us that the Lorentz (and parity) invariant polynomials in the momenta of $n$ particles are generated by the dot products. We extend this result to include the action of an arbitrary permutation group $P\subset S_n$ on the particles, to take account of the quantum-field-theoretic fact that particles can be indistinguishable. Doing so provides a convenient set of variables for describing scattering processes involving identical particles, such as $pp\to jjj$, for which we provide an explicit set of Lorentz and permutation invariant generators.

   hep-phhep-thmath-phmath.MP
3. 03*

   A benchmark for LHC searches for low-mass custodial fiveplet scalars in the Georgi-Machacek model

   Ameen Ismail🇺🇸 · Ben Keeshan🇨🇦 · Heather E. Logan🇨🇦 · Yongcheng Wu🇨🇦

   The Georgi-Machacek (GM) model is used to motivate and interpret LHC searches for doubly charged scalars decaying to vector bosons pairs. The doubly charged scalars are part of a degenerate fermiophobic custodial fiveplet with states $H_5^{\pm \pm }$, $H_5^{\pm }$, and $H_5^0$ and common mass $m_5$. The GM model has been extensively studied at the LHC for $m_5>200$ GeV but there is a largely unprobed region of parameter space from $120$ GeV $<m_5<200$ GeV where light doubly-charged scalars could exist. This region has been neglected by experimental searches due in part to the lack of a benchmark for $m_5<200$ GeV. In this paper we propose a new "low-$m_5$" benchmark for the GM model, defined for $m_5\in (50,550)$ GeV, and characterize its properties. We apply all existing experimental constraints and summarize the phenomenology of the surviving parameter space. We show that the benchmark populates almost the entirety of the relevant allowed parameter plane for $m_5$ below 200 GeV and satisfies the constraints from the 125 GeV Higgs boson signal strengths. We compute the 125 GeV Higgs boson's couplings to fermion and vector boson pairs and show that they are always enhanced in the benchmark relative to those in the Standard Model. We also compute the most relevant production cross sections for $H_5$ at the LHC, including Drell-Yan production of $H_5$ pairs. The process $pp\to H\to H_5{H}_5$ contributes in a small region of parameter space, but is small compared to the Drell-Yan production cross section. Finally we compute the branching ratios of $H_5^0\to \gamma \gamma$ and $H_5^{\pm }\to W^{\pm }\gamma$. The width-to-mass ratio of each of the $H_5$ states is below 1\% over the entire benchmark, so that the narrow-width approximation is well justified.

   hep-phhep-exPRD(2021)·24 citations
4. 04*

   Quark-flavor-changing Higgs decays from a universal extra dimension

   Carlos M. Farrera🇲🇽 · Alejandro Granados-González🇲🇽 · Héctor Novales-Sánchez🇲🇽 · J. Jesús Toscano🇲🇽

   Kaluza-Klein fields characterizing, from a four-dimensional viewpoint, the presence of compact universal extra dimensions would alter low-energy observables through effects determined by some compactification scale, $R^{-1}$, since the one-loop level, thus being particularly relevant for physical phenomena forbidden at tree level by the Standard Model. The present paper explores, for the case of one universal extra dimension, such new-physics contributions to Higgs decays $h^{(0)}\to q_{\alpha }^{(0)}{q}_{\beta }^{(0)}$, into pairs of quarks with different flavors, a sort of decay process which, in the Standard Model, strictly occurs at the loop level. Finite results, decoupling as $R^{-1}\to \infty$, are calculated. Approximate short expressions, valid for large compactification scales, are provided. We estimate that Kaluza-Klein contributions lie below predictions from the Standard Model, being about 2 to 3 orders of magnitude smaller for compactification scales within $1.4\mathrm{TeV}<R^{-1}<10\mathrm{TeV}$.

   hep-phInt.J.Mod.Phys.A(2020)·2 citations
5. 05*

   Revisiting the $P$-wave charmonium radiative decays $h_c\to \gamma {\eta }^{(\prime )}$ with relativistic corrections

   Jun-Kang He🇨🇳 · Chao-Jie Fan🇨🇳

   The $P$-wave charmonium decays $h_c\to \gamma {\eta }^{(\prime )}$ are revisited by taking into account relativistic corrections. The decay amplitudes are derived in the Bethe-Salpeter formalism, in which the involved one-loop integrals are evaluated analytically. Intriguingly, from both the quark-antiquark content and the gluonic content of ${\eta }^{(\prime )}$, the relativistic corrections make significant contributions to the decay rates of $h_c\to \gamma {\eta }^{(\prime )}$. By comparison with the leading-order contributions from the quark-antiquark content (one-loop level), the ones from the gluonic content (tree level) are also important, which is compatible with the conclusion obtained without relativistic corrections. Usually, for $\eta$ production processes, the predicted branching ratios are sensitive to the angle of $\eta -{\eta }^{\prime }$ mixing. As an illustration, using the Feldmann-Kroll-Stech result about the mixing angle $\varphi =39.3^{\circ }\pm 1.0^{\circ }$ as input, we find that the predicted ratio $R_{h_c}=\mathcal{B}(h_c\to \gamma \eta )/\mathcal{B}(h_c\to \gamma {\eta }^{\prime })$ is much smaller than the experiment measurement. While, with $\varphi =33.5^{\circ }\pm 0.9^{\circ }$ extracted from the asymptotic limit of the ${\gamma }^{\ast }\gamma -{\eta }^{\prime }$ transition form factor, we obtain $R_{h_c}=30.3\%$ in consistent with $R_{h_c}^{exp}=(30.7\pm 11.3\pm 8.7)\%$. As a cross-check, the mixing angle $\varphi =33.8^{\circ }\pm 2.5^{\circ }$ is extracted by employing the ratio $R_{h_c}$, and a brief discussion on the difference in the determinations of $\varphi$ is given.

   hep-phPRD(2021)·14 citations
6. 06*

   The Collins asymmetry in electroproduction of Kaon at the electron ion colliders within TMD factorization

   Shi-Chen Xue🇨🇳 · Xiaoyu Wang🇨🇳 · De-Min Li🇨🇳 · Zhun Lu🇨🇳

   We apply the transverse momentum dependent factorization formalism to investigate the transverse single spin dependent Collins asymmetry with a $\sin ({\varphi }_h+{\varphi }_s)$ modulation in the semi-inclusive production of Kaon meson in deep inelastic scattering process. The asymmetry is contributed by the convolutions of the transversity distribution function $h_1(x)$ of the target proton and the Collins function of the Kaon in the final state. We adopt the available parametrization of $h_1(x)$ as well as the recent extracted result for the Kaon Collins function. To perform the transverse momentum dependent evolution, the parametrization of the nonperturbative Sudakov form factor of the proton and final state Kaon are utilized. We numerically predict the Collins asymmetry for charged Kaon production at the electron ion colliders within the accuracy of next-to-leading-logarithmic order. It is found that the asymmetry is sizable and could be measured. We emphasize the importance of planned electron ion colliders in the aspect of constraining sea quark distribution functions as well as accessing the information of the nucleon spin structure and the hadronization mechanism.

   hep-phEPJC(2020)·6 citations
7. 07*

   $D^{(\ast )}N$ interaction and the structure of ${\Sigma }_c(2800)$ and ${\Lambda }_c(2940)$ in chiral effective field theory

   Bo Wang🇨🇳 · Lu Meng🇨🇳 · Shi-Lin Zhu🇨🇳

   We study the $DN$ and $D^{\ast }N$ interactions to probe the inner structure of ${\Sigma }_c(2800)$ and ${\Lambda }_c(2940)$ with the chiral effective field theory to the next-to-leading order. We consider the contact term, one-pion-exchange and two-pion-exchange contributions to characterize the short-, long- and mid-range interactions of the $D^{(\ast )}N$ systems. The low energy constants of the $D^{(\ast )}N$ systems are related to those of the $N\bar{N}$ interaction with quark level Lagrangian that inspired by the resonance saturation model. The $\Delta (1232)$ degree of freedom is also included in the loop diagrams. The attractive potential in the $[DN{]}_{J=1/2}^{I=1}$ channel is too weak to form bound state, which indicates the explanation of ${\Sigma }_c(2800)$ as the compact charmed baryon is more reasonable. Meanwhile, the potentials of the isoscalar channels are deep enough to yield the molecular states. We obtain the masses of the $[DN{]}_{J=1/2}^{I=0}$, $[D^{\ast }N{]}_{J=1/2}^{I=0}$ and $[D^{\ast }N{]}_{J=3/2}^{I=0}$ systems to be $2792.0$ MeV, $2943.6$ MeV and $2938.4$ MeV, respectively. The ${\Lambda }_c(2940)$ is probably the isoscalar $D^{\ast }N$ molecule considering its low mass puzzle. Besides, the ${\Lambda }_c(2940)$ signal might contain the spin-$\frac{1}{2}$ and spin-$\frac{3}{2}$ two structures, which can qualitatively explain the significant decay ratio to $D^{0}p$ and ${\Sigma }_c\pi$. We also study the ${\bar{B}}^{(\ast )}N$ systems and predict the possible molecular states in the isoscalar channels. We hope experimentalists could hunt for the open charmed molecular pentaquarks in the ${\Lambda }_c^{+}{\pi }^{+}{\pi }^{-}$ final state.

   hep-phhep-exnucl-thPRD(2020)·42 citations
8. 08*

   QCD predictions for open charm meson production at the LHCb in fixed-target experiment

   Rafal Maciula🇵🇱

   We investigate open charm meson production in fixed-target LHCb experiment at $\sqrt{s}=86.6$ GeV in $p{+}^4\mathrm{He}$ collisions. Theoretical calculations of charm cross section are done in the framework of the $k_T$-factorization approach. Its application in the kinematical range never examined before is carefully discussed. We consider different schemes for the calculations relevant for different unintegrated (transverse momentum dependent) parton densities in a proton. We include in the analysis both CCFM- and DGLAP-based models of unintegrated parton distributions appropriate for the considered kinematics. Integrated as well as differential cross sections as a function of $D^0$ meson rapidity and transverse momentum are shown and compared with the experimental data. As a reference point, predictions of next-to-leading order collinear approach are also presented and discussed. A very good agreement between the experimental data and the $k_T$-factorization predictions was obtained. Both the CCFM and the DGLAP-based frameworks for parton distributions in a proton are successfully used to explain the LHCb fixed-target open charm cross section.

   hep-phPRD(2020)·8 citations
9. 09*

   X17: A new force, or evidence for a hard $\gamma +\gamma$ process?

   Benjamin Koch🇨🇱

   It is investigated whether the "X17 puzzle" might be explained by a nuclear decay chain and a conversion of the two resulting highly energetic $\gamma$s into an electron-positron pair. It is found that the corresponding kinematics fits perfectly to the experimental result. Also the conversion rates of this process are reasonable. However, the assumed nuclear chain reaction is not favored in the established nuclear models and no explanation for the isospin structure of the signal can be given. Thus, it has to be concluded that the process studied in this paper does not give a completely satisfying explanation of the "X17 puzzle".

   hep-phhep-exnucl-thNPA(2021)·18 citations
10. 10*

    $CP$ asymmetry in the angular distribution of $\tau \to K_S\pi {\nu }_{\tau }$ decays

    Feng-Zhi Chen🇨🇳 · Xin-Qiang Li🇨🇳 · Ya-Dong Yang🇨🇳

    In this work, we study the $CP$ asymmetry in the angular distribution of $\tau \to K_S\pi {\nu }_{\tau }$ decays, taking into account the known $CP$ violation in $K^0-{\bar{K}}^0$ mixing. It is pointed out for the first time that, once the well-measured $CP$ violation in the neutral kaon system is invoked, a non-zero $CP$ asymmetry would appear in the angular observable of the decays considered, even within the Standard Model. By employing the reciprocal basis, which is most convenient when a $K_{S(L)}$ is involved in the final state, the $CP$-violating angular observable is derived to be two times the product of the time-dependent $CP$ asymmetry in $K\to {\pi }^{+}{\pi }^{-}$ and the mean value of the angular distribution in ${\tau }^{\pm }\to K^0({\bar{K}}^0){\pi }^{\pm }{\bar{\nu }}_{\tau }({\nu }_{\tau })$ decays. Compared with the Belle results measured in four different bins of the $K\pi$ invariant mass, our predictions lie within the margins of these measurements, except for a $1.7\sigma$ deviation for the lowest mass bin. While being below the current Belle detection sensitivity that is of $\mathcal{O}(10^{-3})$, our predictions are expected to be detectable at the Belle II experiment, where $\sqrt{70}$ times more sensitive results will be obtained with a $50{\text{ab}}^{-1}$ data sample.

    hep-phhep-exJHEP(2020)·26 citations
11. 11*

    The Weinberg Angle and 5D RGE effects in a SO(11) GUT theory

    Christoph Englert🇬🇧 · David J. Miller🇬🇧 · Dumitru Dan Smaranda🇬🇧

    The Weinberg angle is an important parameter in Grand Unified Theories (GUT) as its size is crucially influenced by the assumption of unification. In scenarios with different steps of symmetry breaking, in particular in models that involve gauge-Higgs unification, the connection of the ultraviolet theory and the TeV scale-relevant, effective Standard Model description is an important test of the models' validity. In this work, we consider a 6D gauge-Higgs unification GUT scenario and explore the TeV scale-GUT relation using a detailed RGE analysis in the 4D and 5D regimes of the theory, including constraints from LHC measurements. We show that such can be consistent with unification in the light of current constraints, while the Weinberg angle likely translates into concrete conditions on the fermion sector in the higher dimensional setup.

    hep-phPLB(2020)·16 citations
12. 12*

    Radiative generation of neutrino masses in a 3-3-1 type model

    Arindam Das🇯🇵 · Kazuki Enomoto🇯🇵 · Shinya Kanemura🇯🇵 · Kei Yagyu🇯🇵

    A new model for tiny neutrino masses is proposed in the gauge theory of $SU(3{)}_C\otimes SU(3{)}_L\otimes U(1{)}_X$, where neutrino masses are generated via the quantum effect of new particles. In this model, the fermion content is taken to be minimal to realize the gauge anomaly cancellation, while the scalar sector is extended from the minimal 3-3-1 model to have an additional $SU(3{)}_L$ triplet field. After $SU(3{)}_L\otimes U(1{)}_X$ is broken into $SU(2{)}_L\otimes U(1{)}_Y$, the "Zee model" like diagrams are naturally induced, which contain sufficient lepton flavor violating interactions to reproduce current neutrino oscillation data. Furthermore, the remnant $Z_2$ symmetry appears after the electroweak symmetry breaking, which guarantees the stability of dark matter. It is confirmed that this model can satisfy current dark matter data. As an important prediction to test this model, productions and decays of doubly-charged scalar bosons at collider experiments are discussed in successful benchmark scenarios.

    hep-phPRD(2020)·9 citations
13. 13*

    Angular distribution and asymmetries in the decay of the polarized charmed baryon ${\Lambda }_c^{+}\to K^{-}{\Delta }^{++}\to K^{-}p{\pi }^{+}$

    A.Yu. Korchin🇺🇦 · V.A. Kovalchuk🇺🇦

    Angular distribution of the final particles in the decay ${\Lambda }_c^{+}\to K^{-}\Delta (1232{)}^{++}\to K^{-}p{\pi }^{+}$ of the polarized charmed baryon is discussed. Asymmetries are proposed which allow for determination of the components of the ${\Lambda }_c^{+}$ polarization vector. The precession angle of the polarization in the process of baryon channeling in a bent crystal is directly related to these asymmetries. The decay rate and asymmetry parameter for the ${\Lambda }_c^{+}\to K^{-}\Delta (1232{)}^{++}$ decay are calculated in the pole model and compared with experiment.

    hep-phInt.J.Mod.Phys.A(2020)·0 citations
14. 14*

    The chirality-flow formalism

    Andrew Lifson🇸🇪 · Christian Reuschle🇸🇪 · Malin Sjodahl🇸🇪

    We take a fresh look at Feynman diagrams in the spinor-helicity formalism. Focusing on tree-level massless QED and QCD, we develop a new and conceptually simple graphical method for their calculation. In this pictorial method, which we dub the chirality-flow formalism, Feynman diagrams are directly represented in terms of chirality-flow lines corresponding to spinor inner products, without the need to resort to intermediate algebraic manipulations.

    hep-phhep-thEPJC(2020)·11 citations
15. 15*

    On the Interpretation of the Balance Function

    V. Vechernin🇷🇺

    We construct a simple toy model and explicitly demonstrate that the Balance Function (BF) can become negative for some values of the rapidity separation and hence can not have any probabilistic interpretation. In particular, the BF can not be interpreted as the probability density for the balancing charges to occur separated by the given rapidity interval.

    hep-phnucl-thSymmetry(2022)·1 citation
16. 16*

    Singlet night in Feynman-ville: one-loop matching of a real scalar

    Ulrich Haisch🇩🇪 · Maximilian Ruhdorfer🇩🇪 · Ennio Salvioni🇨🇭 · Elena Venturini🇩🇪 · Andreas Weiler🇩🇪

    A complete one-loop matching calculation for real singlet scalar extensions of the Standard Model to the Standard Model effective field theory (SMEFT) of dimension-six operators is presented. We compare our analytic results obtained by using Feynman diagrams to the expressions derived in the literature by a combination of the universal one-loop effective action (UOLEA) approach and Feynman calculus. After identifying contributions that have been overlooked in the existing calculations, we find that the pure diagrammatic approach and the mixed method lead to identical results. We highlight some of the subtleties involved in computing one-loop matching corrections in SMEFT.

    hep-phJHEP(2020)·68 citations
17. 17*

    Data Driven Flavour Model

    F. Arias-Aragon🇪🇸 · C. Bouthelier-Madre🇪🇸 · J.M. Cano🇪🇸 · L. Merlo🇪🇸

    A bottom-up approach has been adopted to identify a flavour model that agrees with present experimental measurements. The charged fermion mass hierarchies suggest that only the top Yukawa term should be present at the renormalisable level. Similarly, describing the lightness of the active neutrinos through the type-I Seesaw mechanism, right-handed neutrino mass terms should also be present at the renormalisable level. The flavour symmetry of the Lagrangian including the fermionic kinetic terms and only the top Yukawa is then a combination of $U(2)$ and $U(3)$ factors. Once considering the Majorana neutrino terms, the associated symmetry is $O(3)$. Lighter charged fermion and active neutrino masses and quark and lepton mixings arise considering specific spurion fields {\it à la} Minimal Flavour Violation. The associated phenomenology is investigated and the model turns out to have almost the same flavour protection as the Minimal Flavour Violation in both quark and lepton sectors. Promoting the spurions to dynamical fields, the associated scalar potential is also studied and a minimum is identified such that fermion masses and mixings are correctly reproduced. Very precise predictions for the Majorana phases follow from the minimisation of the scalar potential and thus the neutrinoless-double-beta decay may represent a smoking gun for the model.

    hep-phEPJC(2020)·14 citations
18. 18*

    Charged Higgs boson production via $cb-$fusion at the Large Hadron Collider

    J. Hernandez-Sanchez🇲🇽 · C. G. Honorato🇲🇽 · S. Moretti🇬🇧 · S. Rosado-Navarro🇲🇽

    We analyse the production of a light charged Higgs boson at the Large Hadron Collider (LHC) via the quark-fusion mechanism $c\bar{b}\to H^{-}$ considering the decay channel $H^{-}\to \tau {\bar{\nu }}_{\tau }$ in the final state. We study this process in the framework of the 2-Higgs Doublet Model Type III (2HDM-III) which assumes a four-zero texture in the Yukawa matrices and a general Higgs potential, wherein the two Higgs doublets coupling to both up and down fermions do generate Flavour Changing Neutral Currents (FCNCs) yet the latter can be controlled by the texture when flavour physics constraints are considered. We consider the parameter space of the model where this signal is enhanced and in agreement with both theoretical constraints and experimental data. In particular, we exploit the setup with lepton-specific-like Yukawa couplings and assess the LHC sensitivity to such $H^{\pm }$ signals against the dominant {irreducible and} reducible backgrounds. We show that in our model BR$(H^{\pm }\to cb)\sim 0.1-0.2$ and BR$(H^{\pm }\to \tau \nu )\sim 0.7-0.9$ so that, under these conditions, the prospects for $H^{\pm }$ detection in the 2HDM-III in the aforementioned production and decay channels are excellent assuming standard collider energy and luminosity conditions.

    hep-phhep-exPRD(2020)·18 citations
19. 19*

    Entropy Bound and Unitarity of Scattering Amplitudes

    Gia Dvali🇩🇪

    We establish that unitarity of scattering amplitudes imposes universal entropy bounds. The maximal entropy of a self-sustained quantum field object of radius R is equal to its surface area and at the same time to the inverse running coupling evaluated at the scale R. The saturation of these entropy bounds is in one-to-one correspondence with the non-perturbative saturation of unitarity by 2-to-N particle scattering amplitudes at the point of optimal truncation. These bounds are more stringent than Bekenstein's bound and in a consistent theory all three get saturated simultaneously. This is true for all known entropy-saturating objects such as solitons, instantons, baryons, oscillons, black holes or simply lumps of classical fields. We refer to these collectively as "saturons" and show that in renormalizable theories they behave in all other respects like black holes. Finally, it is argued that the confinement in SU(N) gauge theory can be understood as a direct consequence of the entropy bounds and unitarity.

    ↳ hep-thgr-qchep-phJHEP(2021)·90 citations
20. 20*

    Effects of quark anomalous magnetic moment on the thermodynamical properties and mesonic excitations of magnetized hot and dense matter in PNJL model

    Nilanjan Chaudhuri🇮🇳 · Snigdha Ghosh🇮🇳 · Sourav Sarkar🇮🇳 · Pradip Roy🇮🇳

    Various thermodynamic quantities and the phase diagram of strongly interacting hot and dense magnetized quark matter are obtained with the $2$-flavour Nambu-Jona-Lasinio model with Polyakov loop considering finite values of the anomalous magnetic moment (AMM) of the quarks. Susceptibilities associated with constituent quark mass and traced Polyakov loop are used to evaluate chiral and deconfinement transition temperatures. It is found that, inclusion of the AMM of the quarks in presence of the background magnetic field results in a substantial decrease in the chiral as well as deconfinement transition temperatures in contrast to an enhancement in the chiral transition temperature in its absence. Using standard techniques of finite temperature field theory, the two point thermo-magnetic mesonic correlation functions in the scalar ($\sigma$) and neutral pseudoscalar (${\pi }^0$) channels are evaluated to calculate the masses of $\sigma$ and ${\pi }^0$ considering the AMM of the quarks.

    ↳ nucl-thhep-phEPJA(2020)·46 citations
21. 21*

    The Roper Resonance in a finite volume

    Daniel Severt🇩🇪 · Ulf-G. Meißner🇩🇪

    We calculate the energy levels corresponding to the Roper resonance based on a two-flavor chiral effective Lagrangian for pions, nucleons, deltas and the Roper resonance at leading one-loop order. We show that the Roper mass can be extracted from these levels for not too large lattice volumes.

    ↳ hep-lathep-phnucl-thCommun.Theor.Phys.(2020)·10 citations
22. 22*

    Holographic Entanglement Entropy in Anisotropic Background with Confinement-Deconfinement Phase Transition

    Irina Ya. Aref'eva🇷🇺 · Alexander Patrushev🇷🇺 · Pavel Slepov🇷🇺

    We discuss a general five-dimensional completely anisotropic holographic model with three different spatial scale factors, characterized by a Van der Waals-like phase transition between small and large black holes. A peculiar feature of the model is the relation between anisotropy of the background and anisotropy of the colliding heavy ions geometry. We calculate the holographic entanglement entropy (HEE) of the slab-shaped region, the orientation of which relatively to the beams line and the impact parameter is characterized by the Euler angles. We study the dependences of the HEE and its density on the thermodynamic (temperature, chemical potential) and geometric (parameters of anisotropy, thickness, and orientation of entangled regions) parameters. As a particular case the model with two equal transversal scaling factors is considered. This model is supported by the dilaton and two Maxwell fields. In this case we discuss the HEE and its density in detail: interesting features of this model are jumps of the entanglement entropy and its density near the line of the small/large black hole phase transition. These jumps depend on the anisotropy parameter, chemical potential, and orientation. We also discuss different definitions and behavior of c-functions in this model. The c-function calculated in the Einstein frame decreases while increasing $\ell$ for all $\ell$ in the isotropic case (in regions of $(\mu ,T)$-plane far away from the line of the phase transition). We find the non-monotonicity of the c-functions for several anisotropic configurations, which however does not contradict with any of the existing c-theorems since they all base on Lorentz invariance.

    ↳ hep-thhep-phJHEP(2020)·51 citations
23. 23*

    A collision geometry-based 3D initial condition for relativistic heavy-ion collisions

    Chun Shen🇺🇸 · Sahr Alzhrani🇺🇸

    We present a simple way to construct 3D initial conditions for relativistic heavy-ion collisions based on the Glauber collision geometry. Local energy and momentum conservation conditions are imposed to set non-trivial constraints on our parameterizations of longitudinal profiles for the system's initial energy density and flow velocity. After calibrating parameters with charged hadron rapidity distributions in central Au+Au collisions, we test model predictions for particle rapidity distributions in d+Au and peripheral Au+Au collisions in the Beam Energy Scan (BES) program at Relativistic Heavy-Ion Collider (RHIC). Simulations and comparisons with measurements are also made for Pb+Pb collisions at Super Proton Synchrotron (SPS) energies. We demonstrate that elliptic flow measurements in heavy-ion collisions at $\sqrt{s}\sim 10$ GeV can set strong constraints on the dependence of Quark-Gluon Plasma shear viscosity on temperature and net baryon chemical potential.

    ↳ nucl-thhep-phnucl-exPRC(2020)·144 citations
24. 24*

    Multipoint correlators in multifield cosmology

    George Panagopoulos🇺🇸 · Eva Silverstein🇺🇸

    Connected $N$-point amplitudes in quantum field theory are enhanced by a factor of $N!$ in appropriate regimes of kinematics and couplings, but the non-perturbative analysis of this for collider physics applications is subtle. We resolve this question for $N$-point correlation functions of cosmological perturbations in multifield inflation, and comment on its application to primordial non-Gaussianity. We find that they are calculably $N!$-enhanced using a simple model for the mixing of the field sectors which leads to a convolution of their probability distributions. This effect leads to model-dependent but interesting prospects for enhanced observational sensitivity.

    ↳ hep-thastro-ph.COhep-ph26 citations
25. 25*

    Path integral contour deformations for noisy observables

    William Detmold🇺🇸 · Gurtej Kanwar🇺🇸 · Michael L. Wagman🇺🇸 · Neill C. Warrington🇺🇸

    Monte Carlo studies of many quantum systems face exponentially severe signal-to-noise problems. We show that noise arising from complex phase fluctuations of observables can be reduced without introducing bias using path integral contour deformation techniques. A numerical study of contour deformations for correlation functions in Abelian gauge theory and complex scalar field theory demonstrates that variance can be reduced by orders of magnitude without modifying Monte Carlo sampling.

    ↳ hep-latcond-mat.str-elhep-phhep-thPRD(2020)·45 citations
26. 26*

    Fields of an ultra-relativistic beam of charged particles between parallel plates. Exact 2D solutions by the method of images and applications to the HL-LHC

    B. B. Levchenko🇷🇺

    Exact 2D analytic expressions for E and B fields and their potentials created by a linear beam of relativistic charged particles between infinite perfectly conductive plates and ferromagnetic poles are derived. The solutions are obtained by summing an infinite sequence of fields from linear charge-images and current-images in complex space. Knowledge of the normal component of the E field on the conductor surface makes it possible to calculate the induced electric charge surface density. In addition, we derive within an improved linear approximation new analytical expressions for fields near the beam in the case of an arbitrary beam offset from the median plane. The mathematical features of exact solutions and limitations for the applicability of linear approximations are specified.The primary goals of the future high-luminosity p-p and heavy-ion LHC programme are the search for yet unobserved effects of physics beyond the SM, searches for rare or low-sensitivity processes in the Higgs sector, and probing in more detail the mechanism of EW symmetry breaking. This programme relies on the stable operation of the accelerator. However, as the beam luminosity increases, a number of destabilizing phenomena occur, in particular field emission, enhancing the electron cloud effect. For the case of a proton beam, we apply the exact 2D solution for estimating the intensity of electron field emission activated by the electric field of the beam in collimators of the future high-luminosity LHC. Calculation shows that the field emission intensity is very sensitive to a collimator surface roughness. In addition, with a relatively small and accidental beam displacement from the median path, about 20% of the collimator half-gap, the emission intensity increases by a factor of 1.E+7. This will partially neutralize the beam space charge, violating acceleration dynamics and enhancing instability effects.

    ↳ physics.acc-phhep-exhep-phProgress In Electromagnetics Research C, …·0 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.