Fri·May 11, 2018Friday·May 11, 2018

1. 01*

   Three-pulse photon-photon scattering

   B. King🇬🇧 · H. Hu🇨🇳 · B. Shen🇨🇳

   We calculate signals of real photon-photon scattering in the collision of three laser pulses. Taking goal parameters from the Station of Extreme Light at the upcoming Shanghai Coherent Light Source, we consider two scenarios: i) the collision of three optical pulses; ii) the collision of an XFEL with two optical pulses. Although experimentally more difficult to perform, we find that colliding three laser pulses offers certain advantages in the detection of scattered photons by separating their frequency, momentum and polarisation from the background.

   hep-phphysics.opticsPRA(2018)·61 citations
2. 02*

   A precision test of the nature of Dark Matter and a probe of the QCD phase transition

   Glennys R. Farrar🇺🇸

   If dark matter (DM) contains equal numbers of u,d,s quarks, the ratio of DM and ordinary matter densities is shown to follow from the Boltzmann distribution in the Quark Gluon Plasma. For sexaquark DM in the 1860-1880 MeV mass range (assuring sexaquark and nuclear stability) and quark masses and transition temperature from lattice QCD, the observed Omega_{DM}/Omega_b = 5.3 is in the predicted range, with <~ 15% uncertainty. The prediction is insensitive to the current form of DM, which could be sexaquarks, strange quark matter nuggets, primordial black holes from their collapse, or a mixture of these.

   hep-ph35 citations
3. 03*

   Leading-color fully differential two-loop soft corrections to QCD dipole showers

   Falko Dulat🇺🇸 · Stefan Höche🇺🇸 · Stefan Prestel🇺🇸

   We compute the next-to-leading order corrections to soft-gluon radiation differentially in the one-emission phase space. We show that their contribution to the evolution of color dipoles can be obtained in a modified subtraction scheme, such that both one- and two-emission terms are amenable to Monte-Carlo integration. The two-loop cusp anomalous dimension is recovered naturally upon integration over the full phase space. We present two independent implementations of the new algorithm in the two event generators Pythia and Sherpa, and we compare the resulting fully differential simulation to the CMW scheme.

   hep-phPRD(2018)·89 citations
4. 04*

   A discussion on vacuum polarization correction to the cross-section of $e^{+}{e}^{-}\to {\gamma }^{\ast }/\psi \to {\mu }^{+}{\mu }^{-}$

   Hong-Dou Jin🇨🇳 · Li-Peng Zhou🇨🇳 · Bing-Xin Zhang🇨🇳 · Hai-Ming Hu🇨🇳

   Vacuum polarization is a part of the initial-state radiative correction for the cross-section of $e^{+}{e}^{-}$ annihilation processes. In the energy region in the vicinity of narrow resonances $J/\psi$ and $\psi (3686)$, the vacuum polarization contribution from the resonant component has a significant effect on the line-shape of the lepton pair production cross-section. This paper discusses some basic concepts and describes an analytical calculation of the cross-section of $e^{+}{e}^{-}\to {\gamma }^{\ast }/\psi \to {\mu }^{+}{\mu }^{-}$ considering the single and double vacuum polarization effect of the virtual photon propagator. Moreover, it presents some numerical comparisons with the traditional treatments.

   hep-phhep-thCPC(2019)·4 citations
5. 05*

   Exotic interpretation of ${\Omega }_c$ excited states

   Michal Praszalowicz🇵🇱

   We use the chiral quark-soliton model to interpret five excited ${\Omega }_c$ states recently reported by the LHCb collaboration and confirmed by Belle. We briefly recapitulate the model and its application to light baryons. We then show how the model can be extended to the case of baryons with one heavy quark. We test the model against ground state heavy baryons and then examine possible excitations. We argue that it is not possible to accommodate all five ${\Omega }_c$'s within five parity minus excitations predicetd by the model and propose to interpret two narrowest states split by 70 MeV as pentaquarks belonging to the SU(3) representation $\overline{15}$.

   hep-ph4 citations
6. 06*

   Tests of the Standard Model in Neutron Beta Decay with Polarized Neutron and Electron and Unpolarized Proton

   A. N. Ivanov🇦🇹 · R. Höllwieser🇦🇹 · N. I. Troitskaya🇦🇹 · M. Wellenzohn🇦🇹 · Ya. A. Berdnikov🇷🇺

   We analyse the electron--energy and angular distribution of the neutron beta decay with polarized neutron and electron and unpolarized proton, calculated in Phys. Rev. C 95, 055502 (2017) within the Standard Model (SM), by taking into account the contributions of interactions beyond the SM. After the absorption of vector and axial vector contributions by the axial coupling constant and Cabibbo-Kobayashi-Maskawa (CKM) matrix element (Bhattacharya et al., Phys. Rev. D 85, 054512 (2012) and so on) these are the contributions of scalar and tensor interactions only. The neutron lifetime, correlation coefficients and their averaged values, and asymmetries of the neutron beta decay with polarized neutron and electron are adapted to the analysis of experimental data on searches of contributions of interactions beyond the SM. Using the obtained results we propose some estimates of the values of the scalar and tensor coupling constants of interactions beyond the SM. We use the estimate of the Fierz interference term "b_F = - 0.0028 +/- 0.0026" by Hardy and Towner (Phys. Rev. C 91, 025501 (2015)), the neutron lifetime "tau_n = 880.2(1.0)s"(Particle Data Group, Chin. Phys. C 40, 100001 (2016)) and the experimental data "N_{\exp} = 0.067 +/- 0.011_{\rm stat.} +/- 0.004_{\rm syst.}" for the averaged value of the correlation coefficient of the neutron-electron spin-spin correlations, measured by Kozela et al. (Phys. Ref. C 85, 045501 (2012)). The contributions of G-odd correlations are calculated and found at the level of 10^{-5} in agreement with the results obtained by Gardner and Plaster (Phys. Rev. C 87, 065504 (2013)).

   hep-phastro-ph.COnucl-exPRC(2018)·18 citations
7. 07*

   Neutrino mass generation with large $SU(2{)}_L$ multiplets under local $U(1{)}_{L_{\mu }-L_{\tau }}$ symmetry

   Takaaki Nomura🇰🇷 · Hiroshi Okada🇹🇼

   We propose a model of neutrino mass matrix with large $SU(2)$ multiplets and gauged $U(1{)}_{L_{\mu }-L_{\tau }}$ symmetry, in which we introduce $SU(2)$ quartet scalar and quintet fermions with nonzero $L_{\mu }-L_{\tau }$ charge. Then we investigate the neutrino mass structure and explore phenomenologies of large multiplet fields at the collider, particularly, focussing on doubly- and singly- charged exotic leptons from the quintet.

   hep-phPLB(2018)·28 citations
8. 08*

   $N\Omega$ interaction: meson exchanges, inelastic channels, and quasibound state

   Takayasu Sekihara (JAEA, Ibaraki)🇯🇵 · Yuki Kamiya (Kyoto U., Yukawa Inst., Kyoto)🇯🇵 · Tetsuo Hyodo (Kyoto U., Yukawa Inst., Kyoto)🇯🇵

   Based on a baryon-baryon interaction model with meson exchanges, we investigate the origin of the strong attraction in the $N\Omega ({}^5{S}_2)$ interaction, which was indicated by recent lattice QCD simulations. The long range part of the potential is constructed by the conventional mechanisms, the exchanges of the $\eta$ meson and of the correlated two mesons in the scalar-isoscalar channel, denoted by "$\sigma$" in the literature. The short range part is represented by the contact interaction. We find that the meson exchanges do not provide sufficient attraction. This means that most of the attraction is attributed to the short range contact interaction. We then evaluate the effect of the coupled channels to the $N\Omega ({}^5{S}_2)$ interaction. We find that, while the $D$-wave mixing of the $N\Omega$ channel is negligible, the inelastic $\Lambda \Xi$, $\Sigma \Xi$, and $\Lambda \Xi (1530)$ channels via the $K$ meson exchange give the attraction of the $N\Omega ({}^5{S}_2)$ interaction to the same level with the elastic meson exchanges. Although the elimination of these channels induces the energy dependence of the single-channel $N\Omega$ interaction, this effect is not significant. With the present model parameters fitted to reproduce the scattering length of the HAL QCD result of the nearly physical quark masses, we obtain the $N\Omega ({}^5{S}_2)$ quasibound state with its eigenenergy $2611.3-0.7i$ MeV, which corresponds to the binding energy $0.1$ MeV and width $1.5$ MeV for the decay to the $\Lambda \Xi$ and $\Sigma \Xi$ channels. From the analysis of the spatial structure and the compositeness, the quasibound state is shown to be the molecular state of $N\Omega$. We also construct an equivalent local potential for the $N\Omega ({}^5{S}_2)$ system which is useful for various applications.

   hep-phhep-latnucl-thPRC(2018)·43 citations
9. 09*

   Geometrical scaling for energies available at the BNL Relativistic Heavy Ion Collider to those at the CERN Large Hadron Collider

   M.Petrovici🇷🇴 · A.Lindner🇷🇴 · A.Pop🇷🇴 · M.Tarzila🇷🇴 · I.Berceanu🇷🇴

   Based on the recent RHIC and LHC experimental results, the $⟨p_T⟩$ dependence of identified light flavour charged hadrons on $\sqrt{(\frac{dN}{dy})/S_{\perp }}$, relevant scale in gluon saturation picture, is studied from $\sqrt{s_{NN}}$=7.7 GeV up to 5.02 TeV. This study is extended to the slopes of the $⟨p_T⟩$ dependence on the particle mass and the $⟨{\beta }_T⟩$ parameter from Boltzmann-Gibbs Blast Wave (BGBW) fits of the $p_T$ spectra. A systematic decrease of the slope of the $⟨p_T⟩$ dependence on $\sqrt{(\frac{dN}{dy})/S_{\perp }}$ from BES to the LHC energies is evidenced. While for the RHIC energies, within the experimental errors, the $⟨p_T⟩$/$\sqrt{(\frac{dN}{dy})/S_{\perp }}$ does not depend on centrality, at the LHC energies a deviation from a linear behaviour is observed towards the most central collisions. The influence of the corona contribution to the observed trends is discussed. The slopes of the $⟨p_T⟩$ particle mass dependence and the $⟨{\beta }_T⟩$ parameter from BGBW fits scale well with $\sqrt{(\frac{dN}{dy})/S_{\perp }}$. Similar systematic trends for pp at $\sqrt{s}$=7 TeV are in a good agreement with the ones corresponding to Pb-Pb collisions at $\sqrt{s_{NN}}$=2.76 TeV and 5.02 TeV pointing to a system size independent behaviour.

   hep-phnucl-thPRC(2018)·13 citations
10. 10*

    Opacity dependence of elliptic flow in kinetic theory

    Aleksi Kurkela🇨🇭 · Urs Achim Wiedemann🇨🇭 · Bin Wu🇨🇭

    The observation of large azimuthal anisotropies $v_n$ in the particle spectra of proton-proton (pp) and proton-nucleus (pA) collisions challenges fluid dynamic interpretations of $v_n$, as it remains unclear how small collision systems can hydrodynamize and to what extent hydrodynamization is needed to build up $v_n$. Here, we study in a simple kinetic theory how the same physics that leads to hydrodynamization in large systems represents itself in small systems. We observe that one third to one half of the elliptic flow signal seen in fully hydrodynamized systems can be built up in collisions that extend over only one mean free path $l_{\mathrm{mfp}}$ and that do not hydrodynamize. This is qualitatively in line with observing a sizeable $v_2$ in $pp$ collisions for which other characteristics of soft multi-particle production seem well-described in a free-streaming picture. We further expose a significant system size dependence in the accuracy of hybrid approaches that match kinetic theory to viscous fluid dynamics. The implications of these findings for a reliable extraction of shear viscosity are discussed.

    hep-phhep-exnucl-exnucl-thEPJC(2019)·88 citations
11. 11*

    Beyond $\mathcal{R}(D^{(\ast )})$ with the general 2HDM-III for $b\to c\tau \nu$

    R. Martinez🇨🇴 · C.F. Sierra🇦🇺 · German Valencia🇦🇺

    We review the parameter regions allowed by measurements of $\mathcal{R}(D^{(\ast )})$ and by a theoretical limit on $\mathcal{B}(B_c\to \tau \nu )$ in terms of generic scalar and pseudoscalar new physics couplings, $g_s$ and $g_p$. We then use these regions as constraints to predict the ranges for additional observables in $b\to c\tau \nu$ including the differential decay distributions $d\Gamma /d{q}^2$; the ratios $\mathcal{R}(J/\psi )$ and $\mathcal{R}({\Lambda }_c)$; and the tau-lepton polarisation in $B\to D^{(\star )}\tau \nu$, with emphasis on the CP violating normal polarisation. Finally we map the allowed regions in $g_s$ and $g_p$ into the parameters of four versions of the Yukawa couplings of the general 2HDM-III model. We find that the model is still viable but could be ruled out by a confirmation of a large $\mathcal{R}(J/\psi )$.

    hep-phPRD(2018)·46 citations
12. 12*

    Third family of compact stars within a nonlocal chiral quark model equation of state

    D.E. Alvarez-Castillo🇷🇺 · D.B. Blaschke🇵🇱 · A.G. Grunfeld🇦🇷 · V.P. Pagura🇪🇸

    A class of hybrid compact star equations of state is investigated that joins by a Maxwell construction a low-density phase of hadronic matter, modeled by a relativistic meanfield approach with excluded nucleon volume, with a high-density phase of color superconducting two-flavor quark matter, described within a nonlocal covariant chiral quark model. We find the conditions on the vector meson coupling in the quark model under which a stable branch of hybrid compact stars occurs in the cases with and without diquark condensation. We show that these hybrid stars do not form a third family disconnected from the second family of ordinary neutron stars unless additional (de)confining effects are introduced with a density-dependent bag pressure. A suitably chosen density dependence of the vector meson coupling assures that at the same time the $2$M${}_{\odot }$ maximum mass constraint is fulfilled on the hybrid star branch. A twofold interpolation method is realized which implements both, the density dependence of a confining bag pressure at the onset of the hadron-to-quark matter transition as well as the stiffening of quark matter at higher densities by a density-dependent vector meson coupling. For three parametrizations of this class of hybrid equation of state the properties of corresponding compact star sequences are presented, including mass twins of neutron and hybrid stars at 2.00, 1.39 and 1.20 $M_{\odot }$, respectively. The sensitivity of the hybrid equation of state and the corresponding compact star sequences to variations of the interpolation parameters at the 10% level is investigated and it is found that the feature of third family solutions for compact stars is robust against such a variation. This advanced description of hybrid star matter allows to interpret GW170817 as a merger not only of two neutron stars but also of a neutron star with a hybrid star or of two hybrid stars.

    hep-phnucl-thPRD(2019)·130 citations
13. 13*

    Dark Matter Model or Mass, but Not Both: Assessing Near-Future Direct Searches with Benchmark-free Forecasting

    Thomas D. P. Edwards🇳🇱 · Bradley J. Kavanagh🇳🇱 · Christoph Weniger🇳🇱

    Forecasting the signal discrimination power of dark matter (DM) searches is commonly limited to a set of arbitrary benchmark points. We introduce new methods for benchmark-free forecasting that instead allow an exhaustive exploration and visualization of the phenomenological distinctiveness of DM models, based on standard hypothesis testing. Using this method, we reassess the signal discrimination power of future liquid Xenon and Argon direct DM searches. We quantify the parameter regions where various non-relativistic effective operators, millicharged DM, and magnetic dipole DM can be discriminated, and where upper limits on the DM mass can be found. We find that including an Argon target substantially improves the prospects for reconstructing the DM properties. We also show that only in a small region with DM masses in the range 20-100 GeV and DM-nucleon cross sections a factor of a few below current bounds can near-future Xenon and Argon detectors discriminate both the DM-nucleon interaction and the DM mass simultaneously. In all other regions only one or the other can be obtained.

    hep-phastro-ph.COphysics.data-anPRL(2018)·23 citations
14. 14*

    Neutron disappearance inside the nucleus

    H. Ejiri (RCNP, Osaka University, Osaka, Japan)🇯🇵 · J.D. Vergados (University of Ioannina, Ioannina, Greece)🇬🇷

    We consider the possibility that a neutron may disappear inside the nucleus, which will demonstrate the existence of baryon violating $\Delta B=1$ interactions. It has recently been proposed that such a process may have an effect on the free neutron decay life time. We evaluate the widths for $n\to \chi$ and $n\to \chi \gamma$, with $\chi$ being a light dark matter particle emitted by a loosely bound neutron in various light nuclei. We find that, assuming a mass $m_{\chi }$ close to 938 MeV, the obtained width for $n\to \chi$ in ${}^{11}$Be is much larger than the corresponding beta decay width. This suggests a severe limit on the possible decay channel of $n\to \chi \gamma$ for free neutron.

    hep-phnucl-thJ.Phys.G(2019)·20 citations
15. 15*

    New mechanism producing axions in the AQN model and how the CAST can discover them

    H. Fischer🇩🇪 · X.Liang🇨🇦 · Y. Semertzidis🇰🇷 · A. Zhitnitsky🇨🇦 · K. Zioutas🇬🇷

    We advocate the idea that there is a fundamentally new mechanism for the axion production in the Sun, which has never been discussed previously in the literature. This novel mechanism of the axion production is based on the so-called Axion Quark Nugget (AQN) Dark Matter Model. These axions will be produced in addition to well studied axions emitted due to the Primakoff effect. The AQN model was originally invented as a natural explanation of the observed ratio ${\Omega }_{\mathrm{dark}}\sim {\Omega }_{\mathrm{visible}}$ when the DM and visible matter densities assume the same order of magnitude values, irrespectively to the axion mass $m_a$ or initial misalignment angle ${\theta }_0$. This model, without adjustment of any parameters, reproduces reasonably the intensity of the extreme UV (EUV) radiation from the solar corona as a result of the AQN annihilation events with the solar material. This extra energy released in corona represents a resolution, within AQN framework, a long standing puzzle known in the literature as the "solar corona heating mystery". The same annihilation events also produce the relativistic axions. This represents a new mechanism of the axion production, and constitutes the main subject of this work. The flux of these axions is unambiguously fixed in this model and expressed in terms of the EUV luminosity from corona. We also compute the spectral properties of these axions and make few comments on the potentials for the discovery of these solar axions by the upgraded CAST (CERN Axion Solar Axion) experiment.

    hep-phastro-ph.GAastro-ph.SRPRD(2018)·32 citations
16. 16*

    A Fresh Look at the Calculation of Tunneling Actions

    J.R. Espinosa🇪🇸

    An alternative approach to the calculation of tunneling actions, that control the exponential suppression of the decay of metastable phases, is presented. The new method circumvents the use of bounces in Euclidean space by introducing an auxiliary function, a tunneling potential $V_t$ that connects smoothly the metastable and stable phases of the field potential $V$. The tunneling action is obtained as the integral in field space of an action density that is a simple function of $V_t$ and $V$. This compact expression can be considered as a generalization of the thin-wall action to arbitrary potentials and allows a fast numerical evaluation with a precision below the percent level for typical potentials. The method can also be used to generate potentials with analytic tunneling solutions.

    ↳ hep-thhep-phJCAP(2018)·87 citations
17. 17*

    Longitudinal fluctuations and decorrelations of anisotropic flows at the LHC and RHIC energies

    Xiang-Yu Wu🇨🇳 · Long-Gang Pang🇺🇸 · Guang-You Qin🇨🇳 · Xin-Nian Wang🇨🇳

    We perform a systematic study on the decorrelation of anisotropic flows along the pseudorapidity in relativistic heavy-ion collisions at the LHC and RHIC energies. The dynamical evolution of the QGP fireball is simulated via the CLVisc (ideal) (3+1)-dimensional hydrodynamics model, with the fully fluctuating initial condition from A-Multi-Phase-Transport (AMPT) model. Detailed analysis is performed on the longitudinal decorrelations of elliptic, triangular and quadrangular flows in terms of flow vectors, flow magnitudes and flow orientations (event planes). It is found that pure flow magnitudes have smaller longitudinal decorrelation than pure flow orientations, and the decorrelation of flow vectors is a combined effect of both flow magnitudes and orientations. The longitudinal decorrelation of elliptic flow has a strong and non-monotonic centrality dependence due to the initial elliptic collision geometry: smallest decorrelation in mid-central collisions. In contrast, the decorrelations of triangular and quadrangular flows have weak centrality dependence, slightly larger decorrelations in more peripheral collisions. Our numerical results for Pb+Pb collisions at the LHC are in good agreement with the ATLAS data, while our RHIC results predict much larger longitudinal decorrelations as compared to the LHC. We further analyze the longitudinal structures of the AMPT initial conditions and find that the final-state longitudinal decorrelation effects are strongly correlated with the lengths of the initial string structures in the AMPT model. The decorrelation effects are typically larger at lower collision energies and in more peripheral collisions due to shorter lengths of the string structures in the initial states.

    ↳ nucl-thhep-phnucl-exPRC(2018)·61 citations
18. 18*

    Modified Skellam, Poisson and Gaussian distributions in semi-open systems at charge-like conservation law

    Yuri Sinyukov🇺🇦

    A modification of the Skellam and Poisson distributions is proposed for subsystems when the constraints imposed by the charge conservation law in the complete system are taken into account. Such distributions can be applied, for example, for an analysis of the fluctuations of baryon and net baryon numbers in certain pseudo-rapidity interval in $A+A$ and $p+p$ collisions with high multiplicities. The presented modified Skellam, Poisson and Gaussian distributions can be utilized also in various branches of science, when one studies the fluctuations of the two variables related to a subsystem, as well as the distribution of the difference of these variables, while the mentioned difference in the total system is fixed.

    ↳ nucl-thhep-phphysics.data-an0 citations
19. 19*

    Cosmological Implications of Affine Gravity

    Hemza Azri

    The main aim of this thesis is to reveal some interesting aspects of the purely affine theory of gravity and its cosmological implication. A particular attention will be devoted to its consequences when applied to cosmological inflation. Primarily, affine spacetime, composed of geodesics with no notion of length and angle, accommodates gravity but not matter. The thesis study is expected to reveal salient properties of matter dynamics in affine spacetime and may reveal an intimate connection between vacuum state and metrical gravity. An interesting application of the framework is the inflationary regime, where it is shown that affine gravity prefers only a unique metric tensor such that the transition from nonminimal to minimal coupling of the inflaton is performed only via redefinition of the latter. This allows us to avoid the use of the so called conformal frames. In fact, unlike metric gravity, the metric tensor in affine gravity is generated and not postulated a priori, thus this tensor is absent in the actions and conformal transformation does not make sense. Last but not least, we try to show how metric gravity can be induced through a simple structure that contains only affine connection and scalar fields. General relativity arises classically only at the vacuum, and this view of gravity may be considered as a new way to inducing metric elasticity of space, not through quantum corrections as in standard induced gravity, but only classically. The thesis is concluded by analyzing affine gravity in a particular higher-dimensional manifold (product of two spaces) in an attempt to understand both, the cosmological constant and matter dynamically.

    ↳ gr-qcastro-ph.HEhep-phhep-th6 citations
20. 20*

    Lattice QCD study of the $H$ dibaryon using hexaquark and two-baryon interpolators

    A. Francis🇨🇭 · J.R. Green🇩🇪 · P.M. Junnarkar🇮🇳 · Ch. Miao🇩🇪 · T.D. Rae🇩🇪 · H. Wittig🇩🇪

    We present a lattice QCD spectroscopy study in the isospin singlet, strangeness $-2$ sectors relevant for the conjectured $H$ dibaryon. We employ both local and bilocal interpolating operators to isolate the ground state in the rest frame and in moving frames. Calculations are performed using two flavors of O($a$)-improved Wilson fermions and a quenched strange quark. Our initial point-source method for constructing correlators does not allow for bilocal operators at the source; nevertheless, results from using these operators at the sink indicate that they provide an improved overlap onto the ground state in comparison with the local operators. We also present results, in the rest frame, using a second method based on distillation to compute a hermitian matrix of correlators with bilocal operators at both the source and the sink. This method yields a much more precise and reliable determination of the ground-state energy. In the flavor-SU(3) symmetric case, we apply Lüscher's finite-volume quantization condition to the rest-frame and moving-frame energy levels to determine the $S$-wave scattering phase shift, near and below the two-particle threshold. For a pion mass of 960 MeV, we find that there exists a bound $H$ dibaryon with binding energy $\Delta E=(19\pm 10)$ MeV. In the 27-plet (dineutron) sector, the finite-volume analysis suggests that the existence of a bound state is unlikely.

    ↳ hep-lathep-phnucl-thPRD(2019)·118 citations
21. 21*

    How to test path-length dependence in energy loss mechanisms: analysis leading to a new observable

    Magdalena Djordjevic🇷🇸 · Dusan Zigic🇷🇸 · Marko Djordjevic🇷🇸 · Jussi Auvinen🇷🇸

    When traversing QCD medium, high $p_{\perp }$ partons lose energy, which is typically measured by suppression, and also predicted by various energy loss models. A crucial test of different energy loss mechanisms is how the energy loss depends on the length of traversed medium (so-called path-length dependence). The upcoming experimental results will allow to, at least in principle, for the first time, clearly observe how the energy loss changes with the size of the medium, in particular, by comparing already available $Pb+Pb$ measurements with now upcoming $Xe+Xe$ data at the LHC. However, in practice, to actually perform such test, it becomes crucial to chose an optimal observable. With respect to this, a ratio of observed suppression for the two systems may seem a natural (and frequently mentioned) choice. We, however, show that extracting the path-length dependence from this observable would not be possible. We here provide an analytical derivation based on simple scaling arguments, as well as detailed numerical calculations based on our advanced energy loss framework, showing that a different observable is suitable for this purpose. We call this observable path-length sensitive suppression ratio ($R_L^{AB}$) and provide our predictions before experimental data become available. This predictions also clearly show that this observable will allow a simple comparison of the related theoretical models with the experimental data, and consequently to distinguish between different (underlying) energy loss mechanisms, which is in turn crucial for understanding properties of created QCD medium.

    ↳ nucl-thhep-phPRC(2019)·31 citations
22. 22*

    Relaxation Times for Chiral Transport Phenomena and Spin Polarization in Strongly Coupled Plasma

    Shiyong Li🇺🇸 · Ho-Ung Yee🇺🇸

    We compute the dynamical relaxation times for chiral transport phenomena in strongly coupled regime using the AdS/CFT correspondence. These relaxation times can be a useful proxy for the dynamical time scale for achieving equilibrium spin-polarization of quasi-particles in the presence of magnetic field and fluid vorticity. We identify the Kubo relations for these relaxation times and clarify some previous issues regarding time-dependence of the Chiral Vortical Effect. We study the consequences of imposing time-reversal invariance on parity-odd thermal noise fluctuations that are related to chiral transport coefficients by the fluctuation-dissipation relation. We find that time-reversal invariance dictates the equality between some of the chiral transport coefficients as well as their relaxation times.

    ↳ hep-thhep-phnucl-thPRD(2018)·11 citations
23. 23*

    Dissociation of heavy quarkonium states in rapidly varying strong magnetic field

    Partha Bagchi🇮🇳 · Nirupam Dutta🇮🇳 · Souvik Priyam Adhya🇮🇳 · Bhaswar Chatterjee🇮🇳

    In a transient magnetic field, heavy quarkonium bound states evolve non adiabatically. In presence of a strong magnetic field, $J/\Psi$ and ${\rm Y}(1S)$ become more tightly bound than we expected earlier for a pure thermal medium. We have shown that in a time varying magnetic field, there is a possibility of moderate suppression of $J/\Psi$ through the non adiabatic transition to continuum where as the ${\rm Y}(1S)$ is so tightly bound that can not be dissociated through this process. We have calculated the dissociation probabilities up to the first order in the time dependent perturbation theory for different values of initial magnetic field intensity.

    ↳ nucl-thhep-phMod.Phys.Lett.A(2023)·13 citations
24. 24*

    The abundance of primordial black holes depends on the shape of the inflationary power spectrum

    Cristiano Germani🇪🇸 · Ilia Musco🇪🇸

    In this letter, combining peak theory and the numerical analysis of gravitational collapse in the radiation dominated era, we show that the abundance of primordial blacks holes, generated by an enhancement in the inflationary power spectrum, is extremely dependent on the shape of the peak. Given the amplitude of the power spectrum, we show that the density of primordial black holes generated from a narrow peak, is exponentially smaller than in the case of a broad peak. Specifically, for a top-hat profile of the power spectrum in Fourier space, we find that for having primordial black holes comprising all of the dark matter, one would only need a power spectrum amplitude an order of magnitude smaller than suggested previously whereas in the case of a narrow peak, one would instead need a much larger power spectrum amplitude, which in many cases would invalidate the perturbative analysis of cosmological perturbations. Finally, we show that, although critical collapse gives a broad mass spectrum, the density of primordial black holes formed is dominated by masses roughly equal to the cosmological horizon mass measured at horizon crossing.

    ↳ astro-ph.COgr-qchep-phPRL(2019)·287 citations
25. 25*

    Effective Field Theories in a Finite Volume

    A. Martinez Torres🇧🇷 · S. Prelovsek🇸🇮 · E. Oset🇪🇸 · A. Ramos🇪🇸

    In this talk I present the formalism we have used to analyze Lattice data on two meson systems by means of effective field theories. In particular I present the results obtained from a reanalysis of the lattice data on the $K{D}^{(\ast )}$ systems, where the states $D_{s0}^{\ast }(2317)$ and $D_{s1}^{\ast }(2460)$ are found as bound states of $KD$ and $K{D}^{\ast }$, respectively. We confirm the presence of such states in the lattice data and determine the contribution of the $KD$ channel in the wave function of $D_{s0}^{\ast }(2317)$ and that of $K{D}^{\ast }$ in the wave function of $D_{s1}^{\ast }(2460)$. Our findings indicate a large meson-meson component in the two cases.

    ↳ hep-lathep-phFew Body Syst.(2018)·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.