Measurements of charged-particle production in pp, p–Pb, and Pb–Pb collisions in the toward, away, and transverse regions with the ALICE detector are discussed. These regions are defined event-by-event relative to the azimuthal direction of the charged trigger particle, which is the reconstructed particle with the largest transverse momentum
This content will become publicly available on March 1, 2025
We study the azimuthal angle dependence of the energy-energy correlators
- Award ID(s):
- 1945471
- NSF-PAR ID:
- 10521289
- Publisher / Repository:
- Springer
- Date Published:
- Journal Name:
- Journal of High Energy Physics
- Volume:
- 2024
- Issue:
- 3
- ISSN:
- 1029-8479
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
A bstract in the range 8$$ \left({p}_{\textrm{T}}^{\textrm{trig}}\right) $$ < $$ {p}_{\textrm{T}}^{\textrm{trig}} $$ < 15 GeV/c . The toward and away regions contain the primary and recoil jets, respectively; both regions are accompanied by the underlying event (UE). In contrast, the transverse region perpendicular to the direction of the trigger particle is dominated by the so-called UE dynamics, and includes also contributions from initial- and final-state radiation. The relative transverse activity classifier, , is used to group events according to their UE activity, where$$ {R}_{\textrm{T}}={N}_{\textrm{ch}}^{\textrm{T}}/\left\langle {N}_{\textrm{ch}}^{\textrm{T}}\right\rangle $$ is the charged-particle multiplicity per event in the transverse region and$$ {N}_{\textrm{ch}}^{\textrm{T}} $$ is the mean value over the whole analysed sample. The energy dependence of the$$ \left\langle {N}_{\textrm{ch}}^{\textrm{T}}\right\rangle $$ R Tdistributions in pp collisions at = 2$$ \sqrt{s} $$ . 76, 5.02, 7, and 13 TeV is reported, exploring the Koba-Nielsen-Olesen (KNO) scaling properties of the multiplicity distributions. The first measurements of charged-particlep Tspectra as a function ofR Tin the three azimuthal regions in pp, p–Pb, and Pb–Pb collisions at = 5$$ \sqrt{s_{\textrm{NN}}} $$ . 02 TeV are also reported. Data are compared with predictions obtained from the event generators PYTHIA 8 and EPOS LHC. This set of measurements is expected to contribute to the understanding of the origin of collective-like effects in small collision systems (pp and p–Pb). -
Abstract Let
denote the matrix multiplication tensor (and write$M_{\langle \mathbf {u},\mathbf {v},\mathbf {w}\rangle }\in \mathbb C^{\mathbf {u}\mathbf {v}}{\mathord { \otimes } } \mathbb C^{\mathbf {v}\mathbf {w}}{\mathord { \otimes } } \mathbb C^{\mathbf {w}\mathbf {u}}$ ), and let$M_{\langle \mathbf {n} \rangle }=M_{\langle \mathbf {n},\mathbf {n},\mathbf {n}\rangle }$ denote the determinant polynomial considered as a tensor. For a tensor$\operatorname {det}_3\in (\mathbb C^9)^{{\mathord { \otimes } } 3}$ T , let denote its border rank. We (i) give the first hand-checkable algebraic proof that$\underline {\mathbf {R}}(T)$ , (ii) prove$\underline {\mathbf {R}}(M_{\langle 2\rangle })=7$ and$\underline {\mathbf {R}}(M_{\langle 223\rangle })=10$ , where previously the only nontrivial matrix multiplication tensor whose border rank had been determined was$\underline {\mathbf {R}}(M_{\langle 233\rangle })=14$ , (iii) prove$M_{\langle 2\rangle }$ , (iv) prove$\underline {\mathbf {R}}( M_{\langle 3\rangle })\geq 17$ , improving the previous lower bound of$\underline {\mathbf {R}}(\operatorname {det}_3)=17$ , (v) prove$12$ for all$\underline {\mathbf {R}}(M_{\langle 2\mathbf {n}\mathbf {n}\rangle })\geq \mathbf {n}^2+1.32\mathbf {n}$ , where previously only$\mathbf {n}\geq 25$ was known, as well as lower bounds for$\underline {\mathbf {R}}(M_{\langle 2\mathbf {n}\mathbf {n}\rangle })\geq \mathbf {n}^2+1$ , and (vi) prove$4\leq \mathbf {n}\leq 25$ for all$\underline {\mathbf {R}}(M_{\langle 3\mathbf {n}\mathbf {n}\rangle })\geq \mathbf {n}^2+1.6\mathbf {n}$ , where previously only$\mathbf {n} \ge 18$ was known. The last two results are significant for two reasons: (i) they are essentially the first nontrivial lower bounds for tensors in an “unbalanced” ambient space and (ii) they demonstrate that the methods we use (border apolarity) may be applied to sequences of tensors.$\underline {\mathbf {R}}(M_{\langle 3\mathbf {n}\mathbf {n}\rangle })\geq \mathbf {n}^2+2$ The methods used to obtain the results are new and “nonnatural” in the sense of Razborov and Rudich, in that the results are obtained via an algorithm that cannot be effectively applied to generic tensors. We utilize a new technique, called
border apolarity developed by Buczyńska and Buczyński in the general context of toric varieties. We apply this technique to develop an algorithm that, given a tensorT and an integerr , in a finite number of steps, either outputs that there is no border rankr decomposition forT or produces a list of all normalized ideals which could potentially result from a border rank decomposition. The algorithm is effectively implementable whenT has a large symmetry group, in which case it outputs potential decompositions in a natural normal form. The algorithm is based on algebraic geometry and representation theory. -
A bstract In this paper we explore
pp →W ± (ℓ ± ν )γ to in the SMEFT expansion. Calculations to this order are necessary to properly capture SMEFT contributions that grow with energy, as the interference between energy-enhanced SMEFT effects at$$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ and the Standard Model is suppressed. We find that there are several dimension eight operators that interfere with the Standard Model and lead to the same energy growth, ~$$ \mathcal{O}\left(1/{\Lambda}^2\right) $$ , as dimension six squared. While energy-enhanced SMEFT contributions are a main focus, our calculation includes the complete set of$$ \mathcal{O}\left({E}^4/{\Lambda}^4\right) $$ SMEFT effects consistent with U(3)5flavor symmetry. Additionally, we include the decay of the$$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ W ± → ℓ ± ν , making the calculation actually . As such, we are able to study the impact of non-resonant SMEFT operators, such as$$ \overline{q}{q}^{\prime}\to {\ell}^{\pm}\nu \gamma $$ $$ \left({L}^{\dagger }{\overline{\sigma}}^{\mu }{\tau}^IL\right)\left({Q}^{\dagger }{\overline{\sigma}}^{\nu }{\tau}^IQ\right) $$ B μν , which contribute to directly and not to$$ \overline{q}{q}^{\prime}\to {\ell}^{\pm}\nu \gamma $$ . We show several distributions to illustrate the shape differences of the different contributions.$$ \overline{q}{q}^{\prime}\to {W}^{\pm}\gamma $$ -
A bstract The polarization of
τ leptons is measured using leptonic and hadronicτ lepton decays in Z →τ +τ − events in proton-proton collisions at = 13 TeV recorded by CMS at the CERN LHC with an integrated luminosity of 36.3 fb$$ \sqrt{s} $$ − 1. The measuredτ − lepton polarization at the Z boson mass pole is = −0.144 ± 0.006 (stat) ± 0.014 (syst) = −0.144 ± 0.015, in good agreement with the measurement of the$$ {\mathcal{P}}_{\tau}\left(\textrm{Z}\right) $$ τ lepton asymmetry parameter ofA τ = 0.1439 ± 0.0043 = at LEP. The$$ -{\mathcal{P}}_{\tau}\left(\textrm{Z}\right) $$ τ lepton polarization depends on the ratio of the vector to axial-vector couplings of theτ leptons in the neutral current expression, and thus on the effective weak mixing angle sin2 , independently of the Z boson production mechanism. The obtained value sin2$$ {\theta}_{\textrm{W}}^{\textrm{eff}} $$ = 0.2319 ± 0$$ {\theta}_{\textrm{W}}^{\textrm{eff}} $$ . 0008(stat) ± 0. 0018(syst) = 0. 2319 ± 0. 0019 is in good agreement with measurements ate +e − colliders. -
A bstract We report a search for the charged-lepton flavor violation in Υ(2
S ) →ℓ ∓τ ± (ℓ =e, μ ) decays using a 25 fb− 1Υ(2S ) sample collected by the Belle detector at the KEKBe +e − asymmetric-energy collider. We find no evidence for a signal and set upper limits on the branching fractions ( ) at 90% confidence level. We obtain the most stringent upper limits:$$ \mathcal{B} $$ (Υ(2$$ \mathcal{B} $$ S )→ μ ∓τ ± )< 0. 23× 10− 6and (Υ(2$$ \mathcal{B} $$ S )→ e ∓τ ± )< 1. 12× 10− 6.